Sample records for accurate variational wave

  1. Lamb mode selection for accurate wall loss estimation via guided wave tomography

    NASA Astrophysics Data System (ADS)

    Huthwaite, P.; Ribichini, R.; Lowe, M. J. S.; Cawley, P.

    2014-02-01

    Guided wave tomography offers a method to accurately quantify wall thickness losses in pipes and vessels caused by corrosion. This is achieved using ultrasonic waves transmitted over distances of approximately 1-2m, which are measured by an array of transducers and then used to reconstruct a map of wall thickness throughout the inspected region. To achieve accurate estimations of remnant wall thickness, it is vital that a suitable Lamb mode is chosen. This paper presents a detailed evaluation of the fundamental modes, S0 and A0, which are of primary interest in guided wave tomography thickness estimates since the higher order modes do not exist at all thicknesses, to compare their performance using both numerical and experimental data while considering a range of challenging phenomena. The sensitivity of A0 to thickness variations was shown to be superior to S0, however, the attenuation from A0 when a liquid loading was present was much higher than S0. A0 was less sensitive to the presence of coatings on the surface of than S0.

  2. Rogue wave variational modelling through the interaction of two solitary waves

    NASA Astrophysics Data System (ADS)

    Gidel, Floriane; Bokhove, Onno

    2016-04-01

    The extreme and unexpected characteristics of Rogue waves have made them legendary for centuries. It is only on the 1st of January 1995 that these mariners' tales started to raise scientist's curiosity, when such a wave was recorded in the North Sea; a sudden wall of water hit the Draupner offshore platform, more than twice higher than the other waves, providing evidence of the existence of rogue or freak waves. Since then, studies have shown that these surface gravity waves of high amplitude (at least twice the height of the other sea waves [Dyste et al., 2008]) appear in non-linear dispersive water motion [Drazin and Johnson, 1989], at any depth, and have caused a lot of damage in recent years [Nikolkina and Didenkulova, 2011 ]. So far, most of the studies have tried to determine their probability of occurrence, but no conclusion has been achieved yet, which means that we are currently unenable to predict or avoid these monster waves. An accurate mathematical and numerical water-wave model would enable simulation and observation of this external forcing on boats and offshore structures and hence reduce their threat. In this work, we aim to model rogue waves through a soliton splash generated by the interaction of two solitons coming from different channels at a specific angle. Kodama indeed showed that one way to produce extreme waves is through the intersection of two solitary waves, or one solitary wave and its oblique reflection on a vertical wall [Yeh, Li and Kodama, 2010 ]. While he modelled Mach reflection from Kadomtsev-Petviashvili (KP) theory, we aim to model rogue waves from the three-dimensional potential flow equations and/or their asymptotic equivalent described by Benney and Luke [Benney and Luke, 1964]. These theories have the advantage to allow wave propagation in several directions, which is not the case with KP equations. The initial solitary waves are generated by removing a sluice gate in each channel. The equations are derived through a

  3. Validation of an Accurate Three-Dimensional Helical Slow-Wave Circuit Model

    NASA Technical Reports Server (NTRS)

    Kory, Carol L.

    1997-01-01

    The helical slow-wave circuit embodies a helical coil of rectangular tape supported in a metal barrel by dielectric support rods. Although the helix slow-wave circuit remains the mainstay of the traveling-wave tube (TWT) industry because of its exceptionally wide bandwidth, a full helical circuit, without significant dimensional approximations, has not been successfully modeled until now. Numerous attempts have been made to analyze the helical slow-wave circuit so that the performance could be accurately predicted without actually building it, but because of its complex geometry, many geometrical approximations became necessary rendering the previous models inaccurate. In the course of this research it has been demonstrated that using the simulation code, MAFIA, the helical structure can be modeled with actual tape width and thickness, dielectric support rod geometry and materials. To demonstrate the accuracy of the MAFIA model, the cold-test parameters including dispersion, on-axis interaction impedance and attenuation have been calculated for several helical TWT slow-wave circuits with a variety of support rod geometries including rectangular and T-shaped rods, as well as various support rod materials including isotropic, anisotropic and partially metal coated dielectrics. Compared with experimentally measured results, the agreement is excellent. With the accuracy of the MAFIA helical model validated, the code was used to investigate several conventional geometric approximations in an attempt to obtain the most computationally efficient model. Several simplifications were made to a standard model including replacing the helical tape with filaments, and replacing rectangular support rods with shapes conforming to the cylindrical coordinate system with effective permittivity. The approximate models are compared with the standard model in terms of cold-test characteristics and computational time. The model was also used to determine the sensitivity of various

  4. Determination of wave-function functionals: The constrained-search variational method

    NASA Astrophysics Data System (ADS)

    Pan, Xiao-Yin; Sahni, Viraht; Massa, Lou

    2005-09-01

    In a recent paper [Phys. Rev. Lett. 93, 130401 (2004)], we proposed the idea of expanding the space of variations in variational calculations of the energy by considering the approximate wave function ψ to be a functional of functions χ , ψ=ψ[χ] , rather than a function. A constrained search is first performed over all functions χ such that the wave-function functional ψ[χ] satisfies a physical constraint or leads to the known value of an observable. A rigorous upper bound to the energy is then obtained via the variational principle. In this paper we generalize the constrained-search variational method, applicable to both ground and excited states, to the determination of arbitrary Hermitian single-particle operators as applied to two-electron atomic and ionic systems. We construct analytical three-parameter ground-state functionals for the H- ion and the He atom through the constraint of normalization. We present the results for the total energy E , the expectations of the single-particle operators W=∑irin , n=-2,-1,1,2 , W=∑iδ(ri) , and W=∑iδ(ri-r) , the structure of the nonlocal Coulomb hole charge ρc(rr') , and the expectations of the two particle operators u2,u,1/u,1/u2 , where u=∣ri-rj∣ . The results for all the expectation values are remarkably accurate when compared with the 1078-parameter wave function of Pekeris, and other wave functions that are not functionals. We conclude by describing our current work on how the constrained-search variational method in conjunction with quantal density-functional theory is being applied to the many-electron case.

  5. Effect of Helical Slow-Wave Circuit Variations on TWT Cold-Test Characteristics

    NASA Technical Reports Server (NTRS)

    Kory, Carol L.; Dayton, J. A., Jr.

    1998-01-01

    Recent advances in the state of the art of computer modeling offer the possibility for the first time to evaluate the effect that slow-wave structure parameter variations, such as manufacturing tolerances, have on the cold-test characteristics of helical traveling-wave tubes (TWT's). This will enable manufacturers to determine the cost effectiveness of controlling the dimensions of the component parts of the TWT, which is almost impossible to do experimentally without building a large number of tubes and controlling several parameters simultaneously. The computer code MAFIA is used in this analysis to determine the effect on dispersion and on-axis interaction impedance of several helical slow-wave circuit parameter variations, including thickness and relative dielectric constant of the support rods, tape width, and height of the metallized films deposited on the dielectric rods. Previous computer analyzes required so many approximations that accurate determinations of the effect of many relevant dimensions on tube performance were practically impossible.

  6. Effect of Helical Slow-Wave Circuit Variations on TWT Cold-Test Characteristics

    NASA Technical Reports Server (NTRS)

    Kory, Carol L.; Dayton, James A., Jr.

    1997-01-01

    Recent advances in the state of the art of computer modeling offer the possibility for the first time to evaluate the effect that slow-wave structure parameter variations, such as manufacturing tolerances, have on the cold-test characteristics of helical traveling-wave tubes (TWT's). This will enable manufacturers to determine the cost effectiveness of controlling the dimensions of the component parts of the TWT, which is almost impossible to do experimentally without building a large number of tubes and controlling several parameters simultaneously. The computer code MAFIA is used in this analysis to determine the effect on dispersion and on-axis interaction impedance of several helical slow-wave circuit parameter variations, including thickness and relative dielectric constant of the support rods, tape width, and height of the metallized films deposited on the dielectric rods. Previous computer analyses required so many approximations that accurate determinations of the effect of many relevant dimensions on tube performance were practically impossible.

  7. Effect of Helical Slow-Wave Circuit Variations on TWT Cold-Test Characteristics

    NASA Technical Reports Server (NTRS)

    Kory, Carol L.; Dayton, James A., Jr.

    1998-01-01

    Recent advances in the state of the art of computer modeling offer the possibility for the first time to evaluate the effect that slow-wave structure parameter variations, such'as manufacturing tolerances, have on the cold-test characteristics of helical traveling-wave tubes (TWT's). This will enable manufacturers to determine the cost effectiveness of controlling the dimensions of the component parts of the TWT, which is almost impossible to do experimentally without building a large number of tubes and controlling several parameters simultaneously. The computer code MAxwell's equations by the Finite Integration Algorithm (MAFIA) is used in this analysis to determine the effect on dispersion and on-axis interaction impedance of several helical slow-wave circuit parameter variations, including thickness and relative dielectric constant of the support rods, tape width, and height of the metallized films deposited on the dielectric rods. Previous computer analyzes required so many approximations that accurate determinations of the effect of many relevant dimensions on tube performance were practically impossible.

  8. Variational principles for dissipative waves

    NASA Astrophysics Data System (ADS)

    Dodin, I. Y.; Ruiz, D. E.

    2016-10-01

    Variational methods are a powerful tool in plasma theory. However, their applications are typically restricted to conservative systems or require doubling of variables, which often contradicts the purpose of the variational approach altogether. We show that these restrictions can be relaxed for some classes of dynamical systems that are of practical interest in plasma physics, particularly including dissipative plasma waves. Applications will be discussed to calculating dispersion relations and modulational dynamics of individual plasma waves and wave ensembles. The work was supported by the NNSA SSAA Program through DOE Research Grant No. DE-NA0002948, by the U.S. DOE through Contract No. DE-AC02-09CH11466, and by the U.S. DOD NDSEG Fellowship through Contract No. 32-CFR-168a.

  9. Spatial Variation of Surface Wave Q and Body Wave t* in North America

    NASA Astrophysics Data System (ADS)

    Hwang, Y.; Ritsema, J.

    2007-12-01

    We estimate the spatial variation of the seismic parameter t* using teleseismic (30°--90°) P wave recordings of about 300 deep (> 200 km) earthquakes at broadband stations in North America. We determine the P wave spectral ratio Rij for about 600,000 station pairs i-j with high signal-to-noise ratio P wave signals. The linear fit to lnRij between f= 0.1--1.0 Hz is measured to estimate differential Δt* assuming that lnRij is proportional to π fΔt* (e.g., Aki and Richards, 1980). The measurements are inverted for t* at each station by least-squares inversion. Preliminary inversions indicate that the variation of t* correlate with the tectonic terrains of North America. Predominantly low values of t* are obtained for stations in the Canadian Shield and high t* values in the North American Cordillera. This variation is similar to Q variations inferred from global surface wave amplitude data (e.g., Dalton and Ekström, 2006), suggesting that intrinsic attenuation is the common cause. We will discuss the robustness of our t* estimates (including the effects of scattering on P wave ratios) and make a detailed comparison with surface wave Q maps.

  10. Velocity variations and uncertainty from transdimensional P-wave tomography of North America

    NASA Astrophysics Data System (ADS)

    Burdick, Scott; Lekić, Vedran

    2017-05-01

    High-resolution models of seismic velocity variations constructed using body-wave tomography inform the study of the origin, fate and thermochemical state of mantle domains. In order to reliably relate these variations to material properties including temperature, composition and volatile content, we must accurately retrieve both the patterns and amplitudes of variations and quantify the uncertainty associated with the estimates of each. For these reasons, we image the mantle beneath North America with P-wave traveltimes from USArray using a novel method for 3-D probabilistic body-wave tomography. The method uses a Transdimensional Hierarchical Bayesian framework with a reversible-jump Markov Chain Monte Carlo algorithm in order to generate an ensemble of possible velocity models. We analyse this ensemble solution to obtain the posterior probability distribution of velocities, thereby yielding error bars and enabling rigorous hypothesis testing. Overall, we determine that the average uncertainty (1σ) of compressional wave velocity estimates beneath North America is ∼0.25 per cent dVP/VP, increasing with proximity to complex structure and decreasing with depth. The addition of USArray data reduces the uncertainty beneath the Eastern US by over 50 per cent in the upper mantle and 25-40 per cent below the transition zone and ∼30 per cent throughout the mantle beneath the Western US. In the absence of damping and smoothing, we recover amplitudes of variations 10-80 per cent higher than a standard inversion approach. Accounting for differences in data coverage, we infer that the length scale of heterogeneity is ∼50 per cent longer at shallow depths beneath the continental platform than beneath tectonically active regions. We illustrate the model trade-off analysis for the Cascadia slab and the New Madrid Seismic Zone, where we find that smearing due to the limitations of the illumination is relatively minor.

  11. Phase rainbow refractometry for accurate droplet variation characterization.

    PubMed

    Wu, Yingchun; Promvongsa, Jantarat; Saengkaew, Sawitree; Wu, Xuecheng; Chen, Jia; Gréhan, Gérard

    2016-10-15

    We developed a one-dimensional phase rainbow refractometer for the accurate trans-dimensional measurements of droplet size on the micrometer scale as well as the tiny droplet diameter variations at the nanoscale. The dependence of the phase shift of the rainbow ripple structures on the droplet variations is revealed. The phase-shifting rainbow image is recorded by a telecentric one-dimensional rainbow imaging system. Experiments on the evaporating monodispersed droplet stream show that the phase rainbow refractometer can measure the tiny droplet diameter changes down to tens of nanometers. This one-dimensional phase rainbow refractometer is capable of measuring the droplet refractive index and diameter, as well as variations.

  12. Accurate Cold-Test Model of Helical TWT Slow-Wave Circuits

    NASA Technical Reports Server (NTRS)

    Kory, Carol L.; Dayton, James A., Jr.

    1997-01-01

    Recently, a method has been established to accurately calculate cold-test data for helical slow-wave structures using the three-dimensional electromagnetic computer code, MAFIA. Cold-test parameters have been calculated for several helical traveling-wave tube (TWT) slow-wave circuits possessing various support rod configurations, and results are presented here showing excellent agreement with experiment. The helical models include tape thickness, dielectric support shapes and material properties consistent with the actual circuits. The cold-test data from this helical model can be used as input into large-signal helical TWT interaction codes making it possible, for the first time, to design a complete TWT via computer simulation.

  13. The Effect of Area Variation on Wave Rotor Elements

    NASA Technical Reports Server (NTRS)

    Wilson, Jack

    1997-01-01

    The effect of varying the cross-sectional flow area of the passages of a wave rotor is examined by means of the method of characteristics. An idealized expansion wave, an idealized inlet port, and an idealized compression stage are considered. It is found that area variation does not have a very significant effect on the expansion wave, nor on the compression stage. For the expansion wave, increasing the passage area in the flow direction has the same effect as a diffuser, so that the flow emerges at a lower velocity than it would for the constant area case. This could be advantageous. The inlet is strongly affected by the area variation, as it changes the strength of the hammer shock wave, thereby changing the pressure behind it. In this case, reduction in the passage area in the flow direction leads to increased pressure. However, this result is dependent on the assumption that the inlet conditions remain constant with area variation. This may not be the case.

  14. Accurate expansion of cylindrical paraxial waves for its straightforward implementation in electromagnetic scattering

    NASA Astrophysics Data System (ADS)

    Naserpour, Mahin; Zapata-Rodríguez, Carlos J.

    2018-01-01

    The evaluation of vector wave fields can be accurately performed by means of diffraction integrals, differential equations and also series expansions. In this paper, a Bessel series expansion which basis relies on the exact solution of the Helmholtz equation in cylindrical coordinates is theoretically developed for the straightforward yet accurate description of low-numerical-aperture focal waves. The validity of this approach is confirmed by explicit application to Gaussian beams and apertured focused fields in the paraxial regime. Finally we discuss how our procedure can be favorably implemented in scattering problems.

  15. Longitudinal Variations of Low-Latitude Gravity Waves and Their Impacts on the Ionosphere

    NASA Astrophysics Data System (ADS)

    Cullens, C. Y.; England, S.; Immel, T. J.

    2014-12-01

    The lower atmospheric forcing has important roles in the ionospheric variability. However, influences of lower atmospheric gravity waves on the ionospheric variability are still not clear due to the simplified gravity wave parameterizations and the limited knowledge of gravity wave distributions. In this study, we aim to study the longitudinal variations of gravity waves and their impacts of longitudinal variations of low-latitude gravity waves on the ionospheric variability. Our SABER results show that longitudinal variations of gravity waves at the lower boundary of TIME-GCM are the largest in June-August and January-February. We have implemented these low-latitude gravity wave variations from SABER instrument into TIME-GCM model. TIME-GCM simulation results of ionospheric responses to longitudinal variations of gravity waves and physical mechanisms will be discussed.

  16. An accurate, fast, and scalable solver for high-frequency wave propagation

    NASA Astrophysics Data System (ADS)

    Zepeda-Núñez, L.; Taus, M.; Hewett, R.; Demanet, L.

    2017-12-01

    In many science and engineering applications, solving time-harmonic high-frequency wave propagation problems quickly and accurately is of paramount importance. For example, in geophysics, particularly in oil exploration, such problems can be the forward problem in an iterative process for solving the inverse problem of subsurface inversion. It is important to solve these wave propagation problems accurately in order to efficiently obtain meaningful solutions of the inverse problems: low order forward modeling can hinder convergence. Additionally, due to the volume of data and the iterative nature of most optimization algorithms, the forward problem must be solved many times. Therefore, a fast solver is necessary to make solving the inverse problem feasible. For time-harmonic high-frequency wave propagation, obtaining both speed and accuracy is historically challenging. Recently, there have been many advances in the development of fast solvers for such problems, including methods which have linear complexity with respect to the number of degrees of freedom. While most methods scale optimally only in the context of low-order discretizations and smooth wave speed distributions, the method of polarized traces has been shown to retain optimal scaling for high-order discretizations, such as hybridizable discontinuous Galerkin methods and for highly heterogeneous (and even discontinuous) wave speeds. The resulting fast and accurate solver is consequently highly attractive for geophysical applications. To date, this method relies on a layered domain decomposition together with a preconditioner applied in a sweeping fashion, which has limited straight-forward parallelization. In this work, we introduce a new version of the method of polarized traces which reveals more parallel structure than previous versions while preserving all of its other advantages. We achieve this by further decomposing each layer and applying the preconditioner to these new components separately and

  17. The correlation of VLF propagation variations with atmospheric planetary-scale waves

    NASA Technical Reports Server (NTRS)

    Cavalieri, D. J.; Deland, R. J.; Potemra, T. A.; Gavin, R. F.

    1973-01-01

    Variations in the received daytime phase of long distance, cesium-controlled, VLF transmission were compared to the height variations of the 10-mb isobaric surface during the first three months of 1965 and 1969. The VLF phase values are also compared to height variations of constant electron densities in the E-region and to variations of f-min which have been shown to be well correlated with planetary-scale variations in the stratosphere by Deland and Cavalieri (1973). The VLF phase variations show good correlation with these previous ionospheric measurements and with the 10-mb surfaces. The planetary scale waves in the stratosphere are shown to be travelling on the average eastward in 1965 and westward in 1969. These correlations are interpreted as due to the propagation of travelling planetary scale waves with westward tilted wave fronts. Upward energy transport due to the vertical structure of those waves is also discussed. These correlations provide further evidence for the coupling between the lower ionosphere at about 70 km altitude (the daytime VLF reflection height and the stratosphere, and they demonstrate the importance of planetary wave phenomena to VLF propagation.

  18. Accurate finite difference methods for time-harmonic wave propagation

    NASA Technical Reports Server (NTRS)

    Harari, Isaac; Turkel, Eli

    1994-01-01

    Finite difference methods for solving problems of time-harmonic acoustics are developed and analyzed. Multidimensional inhomogeneous problems with variable, possibly discontinuous, coefficients are considered, accounting for the effects of employing nonuniform grids. A weighted-average representation is less sensitive to transition in wave resolution (due to variable wave numbers or nonuniform grids) than the standard pointwise representation. Further enhancement in method performance is obtained by basing the stencils on generalizations of Pade approximation, or generalized definitions of the derivative, reducing spurious dispersion, anisotropy and reflection, and by improving the representation of source terms. The resulting schemes have fourth-order accurate local truncation error on uniform grids and third order in the nonuniform case. Guidelines for discretization pertaining to grid orientation and resolution are presented.

  19. Multiple-frequency continuous wave ultrasonic system for accurate distance measurement

    NASA Astrophysics Data System (ADS)

    Huang, C. F.; Young, M. S.; Li, Y. C.

    1999-02-01

    A highly accurate multiple-frequency continuous wave ultrasonic range-measuring system for use in air is described. The proposed system uses a method heretofore applied to radio frequency distance measurement but not to air-based ultrasonic systems. The method presented here is based upon the comparative phase shifts generated by three continuous ultrasonic waves of different but closely spaced frequencies. In the test embodiment to confirm concept feasibility, two low cost 40 kHz ultrasonic transducers are set face to face and used to transmit and receive ultrasound. Individual frequencies are transmitted serially, each generating its own phase shift. For any given frequency, the transmitter/receiver distance modulates the phase shift between the transmitted and received signals. Comparison of the phase shifts allows a highly accurate evaluation of target distance. A single-chip microcomputer-based multiple-frequency continuous wave generator and phase detector was designed to record and compute the phase shift information and the resulting distance, which is then sent to either a LCD or a PC. The PC is necessary only for calibration of the system, which can be run independently after calibration. Experiments were conducted to test the performance of the whole system. Experimentally, ranging accuracy was found to be within ±0.05 mm, with a range of over 1.5 m. The main advantages of this ultrasonic range measurement system are high resolution, low cost, narrow bandwidth requirements, and ease of implementation.

  20. Hurricane Directional Wave Spectrum Spatial Variation at Landfall

    NASA Technical Reports Server (NTRS)

    Walsh, Edward J.; Wright, C. Wayne; Vandemark, Douglas C.; Krabill, William B.; Garcia, Andrew W.; Houston, Samuel H.; Powell, Mark D.; Black, Peter G.; Marke, Frank D.; Busalacchi, Antonio J. (Technical Monitor)

    2000-01-01

    On 26 August 1998, hurricane Bonnie was making landfall near Wilmington, NC. The NASA airborne scanning radar altimeter (SRA) carried aboard one of the NOAA WP-3D hurricane hunter aircraft at 2.2 km height documented the sea surface directional wave spectrum in the region between Charleston, SC and Cape Hatteras, NC. The aircraft ground track included both segments along the shoreline and Pamlico Sound as well as far offshore. An animation of the directional wave spectrum spatial variation at landfall will be presented and contrasted with the spatial variation when Bonnie was in the open ocean on 24 August 1998.

  1. Hurricane Directional Wave Spectrum Spatial Variation at Landfall

    NASA Technical Reports Server (NTRS)

    Walsh, E. J.; Wright, C. W.; Vandemark, D.; Krabill, W. B.; Garcia, A. W.

    1999-01-01

    On 26 August 1998, hurricane Bonnie was making landfall near Wilmington, NC. The NASA airborne scanning radar altimeter (SRA) carried aboard one of the NOAA WP-3D hurricane hunter aircraft at 2.2 km height documented the sea surface directional wave spectrum in the region between Charleston, SC and Cape Hatteras, NC. The aircraft ground track included both segments along the shoreline and Pamlico Sound as well as far offshore. An animation of the directional wave spectrum spatial variation at landfall will be presented and contrasted with the spatial variation when Bonnie was in the open ocean on 24 August 1998.

  2. Variational modelling of extreme waves through oblique interaction of solitary waves: application to Mach reflection

    NASA Astrophysics Data System (ADS)

    Gidel, Floriane; Bokhove, Onno; Kalogirou, Anna

    2017-01-01

    In this work, we model extreme waves that occur due to Mach reflection through the intersection of two obliquely incident solitary waves. For a given range of incident angles and amplitudes, the Mach stem wave grows linearly in length and amplitude, reaching up to 4 times the amplitude of the incident waves. A variational approach is used to derive the bidirectional Benney-Luke equations, an asymptotic equivalent of the three-dimensional potential-flow equations modelling water waves. This nonlinear and weakly dispersive model has the advantage of allowing wave propagation in two horizontal directions, which is not the case with the unidirectional Kadomtsev-Petviashvili (KP) equation used in most previous studies. A variational Galerkin finite-element method is applied to solve the system numerically in Firedrake with a second-order Störmer-Verlet temporal integration scheme, in order to obtain stable simulations that conserve the overall mass and energy of the system. Using this approach, we are able to get close to the 4-fold amplitude amplification predicted by Miles.

  3. Density variation effect on multi-ions with kinetic Alfven wave around cusp region—a kinetic approach

    NASA Astrophysics Data System (ADS)

    Tamrakar, Radha; Varma, P.; Tiwari, M. S.

    2018-01-01

    The kinetic Alfven waves in the presence of homogeneous magnetic field plasma with multi-ions effect are investigated. The dispersion relation and normalised damping rate are derived for low-β plasma using kinetic theory. The effect of density variation of H+, He+ and O+ ions is observed on frequency and damping rate of the wave. The variation of frequency (ω) and normalised damping rate (γ / Ω_{H^{ +}} ) of the wave are studied with respect to k_{ \\bot} ρj, where k_{ \\bot} is the perpendicular wave number, ρj is the ion gyroradius and j denotes H+, He+ and O+ ions. The variation with k_{ \\bot} ρj is considered over wide range. The parameters appropriate to cusp region are used for the explanation of results. It is found that with hydrogen and helium ions gyration, the frequency of wave is influenced by the density variation of H+ and He+ ions but remains insensitive to the change in density of O+ ions. For oxygen ion gyration, the frequency of wave varies over a short range only for O+ ion density variation. The wave shows damping at lower altitude due to variation in density of lighter H+ and He+ ions whereas at higher altitude only heavy O+ ions contribute in wave damping. The damping of wave may be due to landau damping or energy transfer from wave to particles. The present study signifies that the both lighter and heavier ions dominate differently to change the characteristics of kinetic Alfven wave and density variation is also an important parameter to understand wave phenomena in cusp region.

  4. A Simple and Accurate Analysis of Conductivity Loss in Millimeter-Wave Helical Slow-Wave Structures

    NASA Astrophysics Data System (ADS)

    Datta, S. K.; Kumar, Lalit; Basu, B. N.

    2009-04-01

    Electromagnetic field analysis of a helix slow-wave structure was carried out and a closed form expression was derived for the inductance per unit length of the transmission-line equivalent circuit of the structure, taking into account the actual helix tape dimensions and surface current on the helix over the actual metallic area of the tape. The expression of the inductance per unit length, thus obtained, was used for estimating the increment in the inductance per unit length caused due to penetration of the magnetic flux into the conducting surfaces following Wheeler’s incremental inductance rule, which was subsequently interpreted for the attenuation constant of the propagating structure. The analysis was computationally simple and accurate, and accrues the accuracy of 3D electromagnetic analysis by allowing the use of dispersion characteristics obtainable from any standard electromagnetic modeling. The approach was benchmarked against measurement for two practical structures, and excellent agreement was observed. The analysis was subsequently applied to demonstrate the effects of conductivity on the attenuation constant of a typical broadband millimeter-wave helical slow-wave structure with respect to helix materials and copper plating on the helix, surface finish of the helix, dielectric loading effect and effect of high temperature operation - a comparative study of various such aspects are covered.

  5. Sensitivity of Gravity Wave Fluxes to Interannual Variations in Tropical Convection and Zonal Wind.

    PubMed

    Alexander, M Joan; Ortland, David A; Grimsdell, Alison W; Kim, Ji-Eun

    2017-09-01

    Using an idealized model framework with high-frequency tropical latent heating variability derived from global satellite observations of precipitation and clouds, the authors examine the properties and effects of gravity waves in the lower stratosphere, contrasting conditions in an El Niño year and a La Niña year. The model generates a broad spectrum of tropical waves including planetary-scale waves through mesoscale gravity waves. The authors compare modeled monthly mean regional variations in wind and temperature with reanalyses and validate the modeled gravity waves using satellite- and balloon-based estimates of gravity wave momentum flux. Some interesting changes in the gravity spectrum of momentum flux are found in the model, which are discussed in terms of the interannual variations in clouds, precipitation, and large-scale winds. While regional variations in clouds, precipitation, and winds are dramatic, the mean gravity wave zonal momentum fluxes entering the stratosphere differ by only 11%. The modeled intermittency in gravity wave momentum flux is shown to be very realistic compared to observations, and the largest-amplitude waves are related to significant gravity wave drag forces in the lowermost stratosphere. This strong intermittency is generally absent or weak in climate models because of deficiencies in parameterizations of gravity wave intermittency. These results suggest a way forward to improve model representations of the lowermost stratospheric quasi-biennial oscillation winds and teleconnections.

  6. Accurate and Standardized Coronary Wave Intensity Analysis.

    PubMed

    Rivolo, Simone; Patterson, Tiffany; Asrress, Kaleab N; Marber, Michael; Redwood, Simon; Smith, Nicolas P; Lee, Jack

    2017-05-01

    Coronary wave intensity analysis (cWIA) has increasingly been applied in the clinical research setting to distinguish between the proximal and distal mechanical influences on coronary blood flow. Recently, a cWIA-derived clinical index demonstrated prognostic value in predicting functional recovery postmyocardial infarction. Nevertheless, the known operator dependence of the cWIA metrics currently hampers its routine application in clinical practice. Specifically, it was recently demonstrated that the cWIA metrics are highly dependent on the chosen Savitzky-Golay filter parameters used to smooth the acquired traces. Therefore, a novel method to make cWIA standardized and automatic was proposed and evaluated in vivo. The novel approach combines an adaptive Savitzky-Golay filter with high-order central finite differencing after ensemble-averaging the acquired waveforms. Its accuracy was assessed using in vivo human data. The proposed approach was then modified to automatically perform beat wise cWIA. Finally, the feasibility (accuracy and robustness) of the method was evaluated. The automatic cWIA algorithm provided satisfactory accuracy under a wide range of noise scenarios (≤10% and ≤20% error in the estimation of wave areas and peaks, respectively). These results were confirmed when beat-by-beat cWIA was performed. An accurate, standardized, and automated cWIA was developed. Moreover, the feasibility of beat wise cWIA was demonstrated for the first time. The proposed algorithm provides practitioners with a standardized technique that could broaden the application of cWIA in the clinical practice as enabling multicenter trials. Furthermore, the demonstrated potential of beatwise cWIA opens the possibility investigating the coronary physiology in real time.

  7. Hurricane Directional Wave Spectrum Spatial Variation in the Open Ocean and at Landfall

    NASA Technical Reports Server (NTRS)

    Walsh, E. J.; Wright, C. W.; Vandemark, D.; Krabill, W. B.; Garcia, A. W.; Houston, S. H.; Powell, M. D.; Black, P. G.; Marks, F. D.; Busalacchi, Antonio J. (Technical Monitor)

    2000-01-01

    The sea surface directional wave spectrum was measured for the first time in all quadrants of a hurricane in open water using the NASA airborne scanning radar altimeter (SRA) carried aboard one of the NOAA WP-3D hurricane hunter aircraft at 1.5 km height. The SRA measures the energetic portion of the directional wave spectrum by generating a topographic map of the sea surface. At 8 Hz, the SRA sweeps a radar beam of 1 E half-power width (two-way) across the aircraft ground track over a swath equal to 0.8 of the aircraft height, simultaneously measuring the backscattered power at its 36 GHz (8.3 mm) operating frequency and the range to the sea surface at 64 positions. These slant ranges are multiplied by the cosine of the incidence angles to determine the vertical distances from the aircraft to the sea surface. Subtracting these distances from the aircraft height produces the sea surface elevation map. The sea surface topography is interpolated to a uniform grid, transformed by a two-dimensional FFT, and Doppler corrected. The open-ocean data were acquired on 24 August 1998 when hurricane Bonnie was east of the Bahamas and moving slowly to the north. Individual waves with heights up to 18 m were observed and the spatial variation of the wave field was dramatic. The dominant waves generally propagated at significant angles to the downwind direction. At some positions there were three different wave fields of comparable energy crossing each other. The NOAA aircraft spent over five hours within 180 km of the hurricane Bonnie eye, and made five eye penetrations. A 3-minute animation of the directional wave spectrum spatial variation over this period will be shown as well as summary plots of the wave field spatial variation. On 26 August 1998, the NOAA aircraft flew at 2.2 km height when hurricane Bonnie was making landfall near Wilmington, NC, documenting the directional wave spectrum in the region between Charleston, SC and Cape Hatteras, NC. The aircraft ground track

  8. A Novel Multimode Waveguide Coupler for Accurate Power Measurement of Traveling Wave Tube Harmonic Frequencies

    NASA Technical Reports Server (NTRS)

    Wintucky, Edwin G.; Simons, Rainee N.

    2014-01-01

    This paper presents the design, fabrication and test results for a novel waveguide multimode directional coupler (MDC). The coupler fabricated from two dissimilar waveguides is capable of isolating the power at the second harmonic frequency from the fundamental power at the output port of a traveling-wave tube (TWT). In addition to accurate power measurements at harmonic frequencies, a potential application of the MDC is in the design of a beacon source for atmospheric propagation studies at millimeter-wave frequencies.

  9. Intraseasonal to interannual variations in the tropical wave activity revealed in reanalyses and their potential impact on the QBO

    NASA Astrophysics Data System (ADS)

    Kim, Young-Ha; Yoo, Changhyun

    2017-04-01

    We investigate activities of tropical waves represented in reanalysis products. The wave activities are quantified by the Eliassen-Palm (EP) flux at 100 hPa, after decomposed into the following four components: equatorially trapped Kelvin waves and mixed Rossby-gravity waves, gravity waves, and Rossby waves. Monthly EP fluxes of the four waves exhibit considerable temporal variations at intraseasonal and interannual, along with seasonal, time scales. These variations are discussed with the tropical large-scale variabilities, including the Madden-Julian Oscillation (MJO), the El Ninõ-Southern Oscillation, and the stratospheric quasi-biennial oscillation (QBO). We find that during boreal winter, the interannual variation of Kelvin wave activity is in phase with that of the MJO amplitude, while such a simultaneous variation cannot be seen in other seasons. The gravity wave is dominated by a semi-annual cycle, while the departure from its semi-annual cycle is largely correlated with the QBO phase in the stratosphere. Potential impacts of the variations in the wave activity upon the QBO properties will be assessed using a simple one-dimensional QBO model.

  10. Use of shear horizontal waves to distinguish adhesive thickness variation from reduction in bonding strength.

    PubMed

    Predoi, Mihai Valentin; Ech Cherif El Kettani, Mounsif; Leduc, Damien; Pareige, Pascal; Coné, Khadidiatou

    2015-08-01

    The capability of shear horizontal (SH) guided waves, to evaluate geometrical imperfections in a bonding layer, is investigated. SH waves are used in a three-layer structure in which the adhesive layer has variable thickness. It is proven that the SH waves are adapting to the local thickness of the adhesive layer (adiabatic waves). This is particularly useful in case of small thickness variations, which is of technical interest. The influence of thickness and stiffness of the adhesive layer on the wavenumbers are investigated. The selected SH2 mode is proven to be very sensitive to the adhesive layer thickness variation in the given frequency range and considerably less sensitive to the adhesive stiffness variation. This property is due to its specific displacement field and is important in practical applications, such as inspection techniques based on SH waves, in order to avoid false alarms.

  11. A fourth order accurate finite difference scheme for the computation of elastic waves

    NASA Technical Reports Server (NTRS)

    Bayliss, A.; Jordan, K. E.; Lemesurier, B. J.; Turkel, E.

    1986-01-01

    A finite difference for elastic waves is introduced. The model is based on the first order system of equations for the velocities and stresses. The differencing is fourth order accurate on the spatial derivatives and second order accurate in time. The model is tested on a series of examples including the Lamb problem, scattering from plane interf aces and scattering from a fluid-elastic interface. The scheme is shown to be effective for these problems. The accuracy and stability is insensitive to the Poisson ratio. For the class of problems considered here it is found that the fourth order scheme requires for two-thirds to one-half the resolution of a typical second order scheme to give comparable accuracy.

  12. Seasonal variation in Rayleigh-to-Love wave ratio in the secondary microseism

    NASA Astrophysics Data System (ADS)

    Tanimoto, T.; Hadziioannou, C.; Igel, H.; Wassermann, J. M.; Schreiber, U.; Gebauer, A.; Chow, B.

    2015-12-01

    The Ring Laser (the G-ring) at Wettzell (WET), Germany, is a rotation-measurement instrument that can monitor tiny variations in seismic noise. It essentially records only SH-type signals. Combined with a co-located seismograph (three-component seismograph STS-2), we can monitor the amount of Love waves from this instrument and that of Rayleigh waves from the STS seismograph. We report on seasonal variation of Rayleigh-to-Love wave ratio in the secondary microseism. The first step in our analysis is to obtain stacked Fourier spectra that were least affected by earthquakes. We used two earthquake catalogues to do this; the GCMT (Global Centroid Moment Tensor, Earthquakes M > 5.5) catalogue and the EMSC (European-Mediterranean Seismic Centre) catalogue for regional earthquakes (distance < 1000 km) with M > 4.5. We then created monthly averages of noise Fourier spectra for the frequency range 0.13-0.30 Hz using both the G-ring and STS data from 2009 to 2015. Monthly spectra show clear seasonal variations for the secondary microseism. We obtained surface vertical acceleration from STS and surface transverse acceleration from G-ring from which we can directly measure the Rayleigh-to-Love wave ratio. The procedure is the same with an account in our recent GRL paper (Tanimoto et al., 2015). Comparison between vertical acceleration and transverse acceleration shows that Rayleigh-wave surface amplitudes are about 20 percent larger than Love waves but in terms of kinetic energy this ratio will be different. We converted these ratios of surface amplitude to those of kinetic energy using an available earth model (Fichtner et al., 2013). The averaged ratio over the frequency band 0.13-0.30 Hz shows is in the range 0.6-0.8 in spring, autumn and winter but it increases to about 1.2 in summer. Except for the summer, the amount of Love waves are higher but the amount of Rayleigh waves increases in summer and appears to exceed that of Love waves.

  13. Hurricane Directional Wave Spectrum Spatial Variation in the Open Ocean

    NASA Technical Reports Server (NTRS)

    Wright, C. W.; Walsh, E. J.; Vandemark, D.; Krabill, W. B.; Garcia, A. W.

    1999-01-01

    The sea surface directional wave spectrum was measured for the first time in all quadrants of a hurricane in open water using the NASA airborne scanning radar altimeter (SRA) carried aboard one of the NOAA WP-3D hurricane hunter aircraft at 1.5 km height. The SRA measures the energetic portion of the directional wave spectrum by generating a topographic map of the sea surface. At 8 Hz, the SRA sweeps a radar beam of 1 deg half-power width (two-way) across the aircraft ground track over a swath equal to 0. 8 of the aircraft height, simultaneously measuring the backscattered power at its 36 GHz (8.3 mm) operating frequency and the range to the sea surface at 64 positions. These slant ranges are multiplied by the cosine of the incidence angles to determine the vertical distances from the aircraft to the sea surface. Subtracting these distances from the aircraft height produces the sea surface elevation map. The sea surface topography is interpolated to a uniform grid, transformed by a two-dimensional FFT, and Doppler corrected. The data presented were acquired on 24 August 1998 when hurricane Bonnie was east of the Bahamas and moving slowly to the north. Wave heights up to 18 m were observed and the spatial variation of the wave field was dramatic. The dominant waves generally propagated at significant angles to the downwind direction and at times there were wave fields traveling at right angles to each other. The NOAA aircraft spent over five hours within 180 km of the hurricane Bonnie eye, and made five eye penetrations. A 2-minute animation of the directional wave spectrum spatial variation over this period will be shown.

  14. Indexed variation graphs for efficient and accurate resistome profiling.

    PubMed

    Rowe, Will P M; Winn, Martyn D

    2018-05-14

    Antimicrobial resistance remains a major threat to global health. Profiling the collective antimicrobial resistance genes within a metagenome (the "resistome") facilitates greater understanding of antimicrobial resistance gene diversity and dynamics. In turn, this can allow for gene surveillance, individualised treatment of bacterial infections and more sustainable use of antimicrobials. However, resistome profiling can be complicated by high similarity between reference genes, as well as the sheer volume of sequencing data and the complexity of analysis workflows. We have developed an efficient and accurate method for resistome profiling that addresses these complications and improves upon currently available tools. Our method combines a variation graph representation of gene sets with an LSH Forest indexing scheme to allow for fast classification of metagenomic sequence reads using similarity-search queries. Subsequent hierarchical local alignment of classified reads against graph traversals enables accurate reconstruction of full-length gene sequences using a scoring scheme. We provide our implementation, GROOT, and show it to be both faster and more accurate than a current reference-dependent tool for resistome profiling. GROOT runs on a laptop and can process a typical 2 gigabyte metagenome in 2 minutes using a single CPU. Our method is not restricted to resistome profiling and has the potential to improve current metagenomic workflows. GROOT is written in Go and is available at https://github.com/will-rowe/groot (MIT license). will.rowe@stfc.ac.uk. Supplementary data are available at Bioinformatics online.

  15. Seismic Velocity and Its Temporal Variations of Hutubi Basin Revealed by Near Surface Trapped Waves

    NASA Astrophysics Data System (ADS)

    Ji, Z.; Wang, B.; Wang, H.; Wang, Q.; Su, J.

    2017-12-01

    Sedimentary basins amplify bypassing seismic waves, which may increase the seismic hazard in basin area. The study of basin structure and its temporal variation is of key importance in the assessment and mitigation of seismic hazard in basins. Recent investigations of seismic exploration have shown that basins may host a distinct wave train with strong energy. It is usually named as Trapped Wave or Whispering Gallery (WG) Phase. In this study, we image the velocity structure and monitor its temporal changes of Hutubi basin in Xinjiang, Northwestern China with trapped wave generated from an airgun source. Hutubi basin is located at mid-segment of the North Tianshan Mountain. Hutubi aigun signal transmitting station was constructed in May 2013. It is composed of six longlife airgun manufactured by BOLT. Prominent trapped waves with strong energy and low velocity are observed within 40km from the source. The airgun source radiates repeatable seismic signals for years. The trapped waves have relative low frequency 0.15s-4s and apparent low velocities of 200m/s to 1000m/s. In the temporal-frequency diagram, at least two groups of wave train can be identified. Based on the group velocity dispersion curves, we invert the S-wave velocity profile of Hutubi basin. The velocity structure is further verified with synthetic seismogram. Velocity variations and Rayleigh wave polarization changes are useful barometers of underground stress status. We observed that the consistent seasonal variations in velocity and polarization. According to the simulate results, we suggest that the variations may be related to the changes of groundwater level and the formation and disappearance of frozen soil.

  16. Hardness variation of welded boron steel using continuous wave (CW) and pulse wave (PW) mode of fiber laser

    NASA Astrophysics Data System (ADS)

    Yaakob, K. I.; Ishak, M.; Idris, S. R. A.; Aiman, M. H.; Khalil, N. Z.

    2017-09-01

    Recent car manufacturer requirement in lightweight and optimum safety lead to utilization of boron steel with tailor welded blank approach. Laser welding process in tailor welded blank (TWB) production can be applied in continuous wave (CW) of pulse wave (PW) which produce different thermal experience in welded area. Instead of microstructure identification, hardness properties also can determine the behavior of weld area. In this paper, hardness variation of welded boron steel using PW and CW mode is investigated. Welding process is conducted using similar average power for both welding mode. Hardness variation across weld area is observed. The result shows similar hardness pattern across weld area for both welding mode. Hardness degradation at fusion zone (FZ) is due to ferrite formation existence from high heat input applied. With additional slower cooling rate for CW mode, the hardness degradation is become obvious. The normal variation of hardness behavior with PW mode might lead to good strength.

  17. Efficient and accurate causal inference with hidden confounders from genome-transcriptome variation data

    PubMed Central

    2017-01-01

    Mapping gene expression as a quantitative trait using whole genome-sequencing and transcriptome analysis allows to discover the functional consequences of genetic variation. We developed a novel method and ultra-fast software Findr for higly accurate causal inference between gene expression traits using cis-regulatory DNA variations as causal anchors, which improves current methods by taking into consideration hidden confounders and weak regulations. Findr outperformed existing methods on the DREAM5 Systems Genetics challenge and on the prediction of microRNA and transcription factor targets in human lymphoblastoid cells, while being nearly a million times faster. Findr is publicly available at https://github.com/lingfeiwang/findr. PMID:28821014

  18. Sensitivity of Rogue Waves Predictions to the Oceanic Stratification

    NASA Astrophysics Data System (ADS)

    Guo, Qiuchen; Alam, Mohammad-Reza

    2014-11-01

    Oceanic rogue waves are short-lived very large amplitude waves (a giant crest typically followed or preceded by a deep trough) that appear and disappear suddenly in the ocean causing damages to ships and offshore structures. Assuming that the state of the ocean at the present time is perfectly known, then the upcoming rogue waves can be predicted via numerically solving the equations that govern the evolution of the waves. The state of the art radar technology can now provide accurate wave height measurement over large spatial domains and when combined with advanced wave-field reconstruction techniques together render deterministic details of the current state of the ocean (i.e. surface elevation and velocity field) at any given moment of the time with a very high accuracy. The ocean water density is, however, stratified (mainly due to the salinity and temperature differences). This density stratification, with today's technology, is very difficult to be measured accurately. As a result in most predictive schemes these density variations are neglected. While the overall effect of the stratification on the average state of the ocean may not be significant, here we show that these density variations can strongly affect the prediction of oceanic rogue waves. Specifically, we consider a broadband oceanic spectrum in a two-layer density stratified fluid, and study via extensive statistical analysis the effects of strength of the stratification (difference between densities) and the depth of the thermocline on the prediction of upcoming rogue waves.

  19. Diagnostic value of QRS and S wave variation in patients with suspicion of acute pulmonary embolism.

    PubMed

    Çağdaş, Metin; Karakoyun, Süleyman; Rencüzoğulları, İbrahim; Karabağ, Yavuz; Artaç, İnanç; İliş, Doğan; Hamideyin, Şerif; Karayol, Sibel; Çiftçi, Handan; Çınar, Tufan

    2018-03-29

    This study aimed to investigate the diagnostic value of QRS and S wave variation in patients admitted to the emergency department with suspicion of acute pulmonary embolism (APE). Computerized tomographic pulmonary angiography (CTPA) was performed in 118 consecutive patients to evaluate patients with suspected APE, and 106 subjects with appropriate electrocardiogram and CT images constituted the study population. Using CTPA, APE was diagnosed in 48.1% (n:51) of the study population. The comparison of patients with APE and those without APE revealed that increased heart rate, right axis deviation of QRS axis, complete or incomplete right bundle branch block, prominent S wave in lead D1, increased QRS duration, percentage of QRS (9,8[4,8-19,0] vs 3,8[2,7-71]; p<0,001), S wave variation (22,3[9,6-31,9] vs 4,8 [2-8]; p<0,001) and ΔS wave amplitude (1.1[0.5-1.5] vs 0.2[0.1-0.5]; p<0.001) were significantly associated with APE, but no relationship was detected with respect to the presence of atrial arrhythmias, clockwise rotation of the horizontal axis, fragmentation, ST segment deviation, T wave inversion, and S1Q3T3 and S1S2S3 patterns. The percentage of S wave variation (OR: 1072 per 1% increase, 95% CI:1011-1137) was found to be an independent predictor of APE. ΔS wave amplitude>0.5mm predicted APE with a sensitivity of 72.6% and a specificity of 74.6% (AUC:0.805, 95% CI: 0.717-0.876; p<0.001). The present study demonstrated that QRS and S wave variation could be useful electrocardiographic signs for the diagnosis of APE. Copyright © 2018. Published by Elsevier Inc.

  20. Spatial and temporal variations of wave energy in the nearshore waters of the central west coast of India

    NASA Astrophysics Data System (ADS)

    Amrutha, M. M.; Sanil Kumar, V.

    2016-12-01

    Assessment of wave power potential at different water depths and time is required for identifying a wave power plant location. This study examines the variation in wave power off the central west coast of India at water depths of 30, 9 and 5 m based on waverider buoy measured wave data. The study shows a significant reduction ( ˜ 10 to 27 %) in wave power at 9 m water depth compared to 30 m and the wave power available at 5 m water depth is 20 to 23 % less than that at 9 m. At 9 m depth, the seasonal mean value of the wave power varied from 1.6 kW m-1 in the post-monsoon period (ONDJ) to 15.2 kW m-1 in the Indian summer monsoon (JJAS) period. During the Indian summer monsoon period, the variation of wave power in a day is up to 32 kW m-1. At 9 m water depth, the mean annual wave power is 6 kW m-1 and interannual variations up to 19.3 % are observed during 2009-2014. High wave energy ( > 20 kW m-1) at the study area is essentially from the directional sector 245-270° and also 75 % of the total annual wave energy is from this narrow directional sector, which is advantageous while aligning the wave energy converter.

  1. Coherent molecular transistor: control through variation of the gate wave function.

    PubMed

    Ernzerhof, Matthias

    2014-03-21

    In quantum interference transistors (QUITs), the current through the device is controlled by variation of the gate component of the wave function that interferes with the wave function component joining the source and the sink. Initially, mesoscopic QUITs have been studied and more recently, QUITs at the molecular scale have been proposed and implemented. Typically, in these devices the gate lead is subjected to externally adjustable physical parameters that permit interference control through modifications of the gate wave function. Here, we present an alternative model of a molecular QUIT in which the gate wave function is directly considered as a variable and the transistor operation is discussed in terms of this variable. This implies that we specify the gate current as well as the phase of the gate wave function component and calculate the resulting current through the source-sink channel. Thus, we extend on prior works that focus on the phase of the gate wave function component as a control parameter while having zero or certain discrete values of the current. We address a large class of systems, including finite graphene flakes, and obtain analytic solutions for how the gate wave function controls the transistor.

  2. A Variational Reduction and the Existence of a Fully Localised Solitary Wave for the Three-Dimensional Water-Wave Problem with Weak Surface Tension

    NASA Astrophysics Data System (ADS)

    Buffoni, Boris; Groves, Mark D.; Wahlén, Erik

    2017-12-01

    Fully localised solitary waves are travelling-wave solutions of the three- dimensional gravity-capillary water wave problem which decay to zero in every horizontal spatial direction. Their existence has been predicted on the basis of numerical simulations and model equations (in which context they are usually referred to as `lumps'), and a mathematically rigorous existence theory for strong surface tension (Bond number {β} greater than {1/3} ) has recently been given. In this article we present an existence theory for the physically more realistic case {0 < β < 1/3} . A classical variational principle for fully localised solitary waves is reduced to a locally equivalent variational principle featuring a perturbation of the functional associated with the Davey-Stewartson equation. A nontrivial critical point of the reduced functional is found by minimising it over its natural constraint set.

  3. A Variational Reduction and the Existence of a Fully Localised Solitary Wave for the Three-Dimensional Water-Wave Problem with Weak Surface Tension

    NASA Astrophysics Data System (ADS)

    Buffoni, Boris; Groves, Mark D.; Wahlén, Erik

    2018-06-01

    Fully localised solitary waves are travelling-wave solutions of the three- dimensional gravity-capillary water wave problem which decay to zero in every horizontal spatial direction. Their existence has been predicted on the basis of numerical simulations and model equations (in which context they are usually referred to as `lumps'), and a mathematically rigorous existence theory for strong surface tension (Bond number {β} greater than {1/3}) has recently been given. In this article we present an existence theory for the physically more realistic case {0 < β < 1/3}. A classical variational principle for fully localised solitary waves is reduced to a locally equivalent variational principle featuring a perturbation of the functional associated with the Davey-Stewartson equation. A nontrivial critical point of the reduced functional is found by minimising it over its natural constraint set.

  4. A More Accurate and Efficient Technique Developed for Using Computational Methods to Obtain Helical Traveling-Wave Tube Interaction Impedance

    NASA Technical Reports Server (NTRS)

    Kory, Carol L.

    1999-01-01

    The phenomenal growth of commercial communications has created a great demand for traveling-wave tube (TWT) amplifiers. Although the helix slow-wave circuit remains the mainstay of the TWT industry because of its exceptionally wide bandwidth, until recently it has been impossible to accurately analyze a helical TWT using its exact dimensions because of the complexity of its geometrical structure. For the first time, an accurate three-dimensional helical model was developed that allows accurate prediction of TWT cold-test characteristics including operating frequency, interaction impedance, and attenuation. This computational model, which was developed at the NASA Lewis Research Center, allows TWT designers to obtain a more accurate value of interaction impedance than is possible using experimental methods. Obtaining helical slow-wave circuit interaction impedance is an important part of the design process for a TWT because it is related to the gain and efficiency of the tube. This impedance cannot be measured directly; thus, conventional methods involve perturbing a helical circuit with a cylindrical dielectric rod placed on the central axis of the circuit and obtaining the difference in resonant frequency between the perturbed and unperturbed circuits. A mathematical relationship has been derived between this frequency difference and the interaction impedance (ref. 1). However, because of the complex configuration of the helical circuit, deriving this relationship involves several approximations. In addition, this experimental procedure is time-consuming and expensive, but until recently it was widely accepted as the most accurate means of determining interaction impedance. The advent of an accurate three-dimensional helical circuit model (ref. 2) made it possible for Lewis researchers to fully investigate standard approximations made in deriving the relationship between measured perturbation data and interaction impedance. The most prominent approximations made

  5. Quasi-biennial variation of equatorial waves as seen in satellite remote sensing data

    NASA Astrophysics Data System (ADS)

    Chen, Zeyu

    The quasi-biennial oscillation (QBO) in zonal winds in the lower stratosphere at the Equator is the most prominent inter-annual variation signal in the middle atmosphere. Theoretically, it is driven by the drag from the damping of equatorial waves including the equatorially trapped planetary scale waves, such as Kelvin waves propagating eastward and Rossby-gravity waves propagating westward, inertio-gravity waves and gravity waves. In current research, the tem-perature data collected by the SABER/TIMED mission in 2002-2009 are used to investigate the equatorial waves activities. The Fast Fourier Synoptic Mapping (FFSM) method is applied to delineate planetary wave components with the zonal wavenumber spanning over -6 to +6, hereby, positive (negative) wavenumber is assigned to westward (eastward) propagating waves. Limited by the SABER/TIMED sampling scheme, only the waves with periods longer than one day can be resolved. Focusing on the height region 70-10 hPa where the QBO signal is most significant, it is clearly observed that the composite activity of all the eastward waves exhibit QBO like variation. Specifically, for each QBO cycle, the activity at 50 hPa level is characterized by the occurrence of a substantially clear minimum that coincides to the fast downward propagation of the westerly phase, the typical pattern of the QBO phenomenon. Phase speed spectra are derived by using the FFSM analysis results. And vertical shear of the zonal wind is derived by using the rawinsonde data at Singapore. Comparison of the phase speed spectra and the wind shear indicates that the minimum is due to the westerly shear below 30 hPa. Between the minimum, significant wave activities emerge, thus the property for the components are investigated. Results show that in height range 70-10 hPa, both wave 1 to wave 3 are prominent during the inter-minimum period for each QBO cycle. At 50 hPa level, wave 1 component exhibits amplitude spectral peak at three kinds of period, 8, 11

  6. Excitation variance matching with limited configuration interaction expansions in variational Monte Carlo

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Robinson, Paul J.; Pineda Flores, Sergio D.; Neuscamman, Eric

    In the regime where traditional approaches to electronic structure cannot afford to achieve accurate energy differences via exhaustive wave function flexibility, rigorous approaches to balancing different states’ accuracies become desirable. As a direct measure of a wave function’s accuracy, the energy variance offers one route to achieving such a balance. Here, we develop and test a variance matching approach for predicting excitation energies within the context of variational Monte Carlo and selective configuration interaction. In a series of tests on small but difficult molecules, we demonstrate that the approach it is effective at delivering accurate excitation energies when the wavemore » function is far from the exhaustive flexibility limit. Results in C3, where we combine this approach with variational Monte Carlo orbital optimization, are especially encouraging.« less

  7. Excitation variance matching with limited configuration interaction expansions in variational Monte Carlo

    DOE PAGES

    Robinson, Paul J.; Pineda Flores, Sergio D.; Neuscamman, Eric

    2017-10-28

    In the regime where traditional approaches to electronic structure cannot afford to achieve accurate energy differences via exhaustive wave function flexibility, rigorous approaches to balancing different states’ accuracies become desirable. As a direct measure of a wave function’s accuracy, the energy variance offers one route to achieving such a balance. Here, we develop and test a variance matching approach for predicting excitation energies within the context of variational Monte Carlo and selective configuration interaction. In a series of tests on small but difficult molecules, we demonstrate that the approach it is effective at delivering accurate excitation energies when the wavemore » function is far from the exhaustive flexibility limit. Results in C3, where we combine this approach with variational Monte Carlo orbital optimization, are especially encouraging.« less

  8. Accurate donor electron wave functions from a multivalley effective mass theory.

    NASA Astrophysics Data System (ADS)

    Pendo, Luke; Hu, Xuedong

    Multivalley effective mass (MEM) theories combine physical intuition with a marginal need for computational resources, but they tend to be insensitive to variations in the wavefunction. However, recent papers suggest full Bloch functions and suitable central cell donor potential corrections are essential to replicating qualitative and quantitative features of the wavefunction. In this talk, we consider a variational MEM method that can accurately predict both spectrum and wavefunction of isolated phosphorus donors. As per Gamble et. al, we employ a truncated series representation of the Bloch function with a tetrahedrally symmetric central cell correction. We use a dynamic dielectric constant, a feature commonly seen in tight-binding methods. Uniquely, we use a freely extensible basis of either all Slater- or all Gaussian-type functions. With a large basis able to capture the influence of higher energy eigenstates, this method is well positioned to consider the influence of external perturbations, such as electric field or applied strain, on the charge density. This work is supported by the US Army Research Office (W911NF1210609).

  9. Combining Probability Distributions of Wind Waves and Sea Level Variations to Assess Return Periods of Coastal Floods

    NASA Astrophysics Data System (ADS)

    Leijala, U.; Bjorkqvist, J. V.; Pellikka, H.; Johansson, M. M.; Kahma, K. K.

    2017-12-01

    Predicting the behaviour of the joint effect of sea level and wind waves is of great significance due to the major impact of flooding events in densely populated coastal regions. As mean sea level rises, the effect of sea level variations accompanied by the waves will be even more harmful in the future. The main challenge when evaluating the effect of waves and sea level variations is that long time series of both variables rarely exist. Wave statistics are also highly location-dependent, thus requiring wave buoy measurements and/or high-resolution wave modelling. As an initial approximation of the joint effect, the variables may be treated as independent random variables, to achieve the probability distribution of their sum. We present results of a case study based on three probability distributions: 1) wave run-up constructed from individual wave buoy measurements, 2) short-term sea level variability based on tide gauge data, and 3) mean sea level projections based on up-to-date regional scenarios. The wave measurements were conducted during 2012-2014 on the coast of city of Helsinki located in the Gulf of Finland in the Baltic Sea. The short-term sea level distribution contains the last 30 years (1986-2015) of hourly data from Helsinki tide gauge, and the mean sea level projections are scenarios adjusted for the Gulf of Finland. Additionally, we present a sensitivity test based on six different theoretical wave height distributions representing different wave behaviour in relation to sea level variations. As these wave distributions are merged with one common sea level distribution, we can study how the different shapes of the wave height distribution affect the distribution of the sum, and which one of the components is dominating under different wave conditions. As an outcome of the method, we obtain a probability distribution of the maximum elevation of the continuous water mass, which enables a flexible tool for evaluating different risk levels in the

  10. Seasonal variations of reflexibility and transmissibility of ULF waves propagating through the ionosphere of geomagnetic mid-latitudes

    NASA Astrophysics Data System (ADS)

    Prikner, K.

    Using reference models of the daytime and night ionosphere of geomagnetic mid-latitudes in a quiescent period in summer, autumn and winter, the seasonal variation of ULF frequency characteristics of amplitude and energy correction factors of the ionosphere - vertical reflexibility, transmissibility, are studied. The existence of two frequency bands within the ULF range with different properties of ionospheric wave filtration is pointed out: (1) continuous band f 0.1-0.2 Hz with the mirror effect of the ionosphere with respect to the incident wave, but with small ionospheric absorption of wave energy; (2) the f 0.2 Hz band with resonance frequency windows and wave emissions with a sharply defined frequency structure. The seasonal variation from summer to winter indicates a decrease in wave energy absorption in the ionosphere and a slight displacement of the resonances towards higher frequencies.

  11. Under-estimated wave contribution to coastal sea-level rise

    NASA Astrophysics Data System (ADS)

    Melet, Angélique; Meyssignac, Benoit; Almar, Rafael; Le Cozannet, Gonéri

    2018-03-01

    Coastal communities are threatened by sea-level changes operating at various spatial scales; global to regional variations are associated with glacier and ice sheet loss and ocean thermal expansion, while smaller coastal-scale variations are also related to atmospheric surges, tides and waves. Here, using 23 years (1993-2015) of global coastal sea-level observations, we examine the contribution of these latter processes to long-term sea-level rise, which, to date, have been relatively less explored. It is found that wave contributions can strongly dampen or enhance the effects of thermal expansion and land ice loss on coastal water-level changes at interannual-to-multidecadal timescales. Along the US West Coast, for example, negative wave-induced trends dominate, leading to negative net water-level trends. Accurate estimates of past, present and future coastal sea-level rise therefore need to consider low-frequency contributions of wave set-up and swash.

  12. Lateral variation in crustal and mantle structure in Bay of Bengal based on surface wave data

    NASA Astrophysics Data System (ADS)

    Kumar, Amit; Mukhopadhyay, Sagarika; Kumar, Naresh; Baidya, P. R.

    2018-01-01

    Surface waves generated by earthquakes that occurred near Sumatra, Andaman-Nicobar Island chain and Sunda arc are used to estimate crustal and upper mantle S wave velocity structure of Bay of Bengal. Records of these seismic events at various stations located along the eastern coast of India and a few stations in the north eastern part of India are selected for such analysis. These stations lie within regional distance of the selected earthquakes. The selected events are shallow focused with magnitude greater than 5.5. Data of 65, 37, 36, 53 and 36 events recorded at Shillong, Bokaro, Visakhapatnam, Chennai and Trivandrum stations respectively are used for this purpose. The ray paths from the earthquake source to the recording stations cover different parts of the Bay of Bengal. Multiple Filtering Technique (MFT) is applied to compute the group velocities of surface waves from the available data. The dispersion curves thus obtained for this data set are within the period range of 15-120 s. Joint inversion of Rayleigh and Love wave group velocity is carried out to obtain the subsurface information in terms of variation of S wave velocity with depth. The estimated S wave velocity at a given depth and layer thickness can be considered to be an average value for the entire path covered by the corresponding ray paths. However, we observe variation in the value of S wave velocity and layer thickness from data recorded at different stations, indicating lateral variation in these two parameters. Thick deposition of sediments is observed along the paths followed by surface waves to Shillong and Bokaro stations. Sediment thickness keeps on decreasing as the surface wave paths move further south. Based on velocity variation the sedimentary layer is further divided in to three parts; on top lay unconsolidated sediment, underlain by consolidated sediment. Below this lies a layer which we consider as meta-sediments. The thickness and velocity of these layers decrease from north

  13. Instant Variations in Velocity and Attenuation of Seismic Waves in a Friable Medium Under a Vibrational Dynamic Loading

    NASA Astrophysics Data System (ADS)

    Geza, N.; Yushin, V.

    2007-12-01

    Instant variations of the velocities and attenuation of seismic waves in a friable medium subjected to dynamic loading have been studied by new experimental techniques using a powerful seismic vibrator. The half-space below the operating vibrator baseplate was scanned by high-frequency elastic waves, and the recorded fluctuations were exposed to a stroboscopic analysis. It was found that the variations of seismic velocities and attenuation are synchronous with the external vibrational load but have phase shift from it. Instant variations of the seismic waves parameters depend on the magnitude and absolute value of deformation, which generally result in decreasing of the elastic-wave velocities. New experimental techniques have a high sensitivity to the dynamic disturbance in the medium and allow one to detect a weak seismic boundaries. The relaxation process after dynamic vibrational loading were investigated and the results of research are presented.

  14. Ultrasonic wave based pressure measurement in small diameter pipeline.

    PubMed

    Wang, Dan; Song, Zhengxiang; Wu, Yuan; Jiang, Yuan

    2015-12-01

    An effective non-intrusive method of ultrasound-based technique that allows monitoring liquid pressure in small diameter pipeline (less than 10mm) is presented in this paper. Ultrasonic wave could penetrate medium, through the acquisition of representative information from the echoes, properties of medium can be reflected. This pressure measurement is difficult due to that echoes' information is not easy to obtain in small diameter pipeline. The proposed method is a study on pipeline with Kneser liquid and is based on the principle that the transmission speed of ultrasonic wave in pipeline liquid correlates with liquid pressure and transmission speed of ultrasonic wave in pipeline liquid is reflected through ultrasonic propagation time providing that acoustic distance is fixed. Therefore, variation of ultrasonic propagation time can reflect variation of pressure in pipeline. Ultrasonic propagation time is obtained by electric processing approach and is accurately measured to nanosecond through high resolution time measurement module. We used ultrasonic propagation time difference to reflect actual pressure in this paper to reduce the environmental influences. The corresponding pressure values are finally obtained by acquiring the relationship between variation of ultrasonic propagation time difference and pressure with the use of neural network analysis method, the results show that this method is accurate and can be used in practice. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. [SEASONAL VARIATION OF MICROVOLT T-WAVE ALTERNANS IN PATIENTS WITH CARDIOVASCULAR DISEASE AND HEALTHY SUBJECTS].

    PubMed

    Halabi, Gh; Bulanova, N; Aleksandrova, S; Ivanov, G; Aleksandrova, M

    2018-05-01

    Objective - to access seasonal variation of microvolt T-wave alternans of ECG dispersion mapping in patients with cardiovascular disease and healthy subjects. ECG data of the three groups of healthy subjects have been compared: inhabitants of Beirut, Lebanon (n=51), inhabitants of Moscow, Russia (n=94) and ECG data of healthy subjects (n=44) from the testing ECG database of the PTB - The National Metrology Institute of Germany as well as a group of patients with cardiovascular disease (n=138), inhabitants of Beirut, Lebanon. Microvolt T-wave alternans of ECG dispersion mapping was evaluated in three points - Tbeginning, Tmaximum, Tend. In healthy subjects, the seasonal variation of ECG dispersion mapping microvolt T-wave alternans was nonexistent. Myocardial lesion is characterized by an increase in Tbeg, Tmax, Tend in relation to the healthy individuals. Tbeg values are minimal in winter and summer and increase in spring and autumn. Tend values were reversed - they were maximal in winter and summer, decreasing in spring-autumn period. Seasonal variation of Tmax - Tbeg, and Tmax -Tend was detected: Tmax - Tbeg increased in the winter-summer period and decreased in spring and autumn, Tmax-Tend - increased in the spring-autumn period in relation to the winter-summer period. In patients with cardiovascular disease, in contrast to the healthy, there is a seasonal variation in microvolt T-wave alternans of ECG dispersion mapping, with the maximum differences in the winter and spring seasons, which should be taken into account when applying the method in clinical practice.

  16. Wave-function functionals

    NASA Astrophysics Data System (ADS)

    Pan, Xiao-Yin; Slamet, Marlina; Sahni, Viraht

    2010-04-01

    We extend our prior work on the construction of variational wave functions ψ that are functionals of functions χ:ψ=ψ[χ] rather than simply being functions. In this manner, the space of variations is expanded over those of traditional variational wave functions. In this article we perform the constrained search over the functions χ chosen such that the functional ψ[χ] satisfies simultaneously the constraints of normalization and the exact expectation value of an arbitrary single- or two-particle Hermitian operator, while also leading to a rigorous upper bound to the energy. As such the wave function functional is accurate not only in the region of space in which the principal contributions to the energy arise but also in the other region of the space represented by the Hermitian operator. To demonstrate the efficacy of these ideas, we apply such a constrained search to the ground state of the negative ion of atomic hydrogen H-, the helium atom He, and its positive ions Li+ and Be2+. The operators W whose expectations are obtained exactly are the sum of the single-particle operators W=∑irin,n=-2,-1,1,2, W=∑iδ(ri), W=-(1)/(2)∑i∇i2, and the two-particle operators W=∑nun,n=-2,-1,1,2, where u=|ri-rj|. Comparisons with the method of Lagrangian multipliers and of other constructions of wave-function functionals are made. Finally, we present further insights into the construction of wave-function functionals by studying a previously proposed construction of functionals ψ[χ] that lead to the exact expectation of arbitrary Hermitian operators. We discover that analogous to the solutions of the Schrödinger equation, there exist ψ[χ] that are unphysical in that they lead to singular values for the expectations. We also explain the origin of the singularity.

  17. Seasonal variations of reflexibility and transmissibility of ULF waves propagating through the ionosphere of geomagnetic mid-latitudes

    NASA Astrophysics Data System (ADS)

    Prikner, K.

    Using reference models of the daytime and night ionosphere of geomagnetic mid-latitudes in a quiescent period in summer, autumn and winter, the seasonal variation of ULF frequency characteristics of amplitude and energy correction factors of the ionosphere - vertical reflexibility, transmissibility and absorption, are studied. The existence of two frequency bands within the ULF range with different properties of ionospheric wave filtration is pointed out: (a) continuous band f of less than 0.1 to 0.2 Hz with the mirror effect of the ionosphere with respect to the incident wave, but with small ionospheric absorption of wave energy; and (b) a Hz band of greater than 0.2 Hz with resonance frequency windows and wave emissions with a sharply defined frequency structure. The seasonal variation from summer to winter indicates a decrease in wave energy absorption in the ionosphere and a slight displacement of the resonances towards higher frequencies.

  18. Variational stereo imaging of oceanic waves with statistical constraints.

    PubMed

    Gallego, Guillermo; Yezzi, Anthony; Fedele, Francesco; Benetazzo, Alvise

    2013-11-01

    An image processing observational technique for the stereoscopic reconstruction of the waveform of oceanic sea states is developed. The technique incorporates the enforcement of any given statistical wave law modeling the quasi-Gaussianity of oceanic waves observed in nature. The problem is posed in a variational optimization framework, where the desired waveform is obtained as the minimizer of a cost functional that combines image observations, smoothness priors and a weak statistical constraint. The minimizer is obtained by combining gradient descent and multigrid methods on the necessary optimality equations of the cost functional. Robust photometric error criteria and a spatial intensity compensation model are also developed to improve the performance of the presented image matching strategy. The weak statistical constraint is thoroughly evaluated in combination with other elements presented to reconstruct and enforce constraints on experimental stereo data, demonstrating the improvement in the estimation of the observed ocean surface.

  19. Effects of temperature variations on guided waves propagating in composite structures

    NASA Astrophysics Data System (ADS)

    Shoja, Siavash; Berbyuk, Viktor; Boström, Anders

    2016-04-01

    Effects of temperature on guided waves propagating in composite materials is a well-known problem which has been investigated in many studies. The majority of the studies is focused on effects of high temperature. Understanding the effects of low temperature has major importance in composite structures and components which are operating in cold climate conditions such as e.g. wind turbines operating in cold climate regions. In this study first the effects of temperature variations on guided waves propagating in a composite plate is investigated experimentally in a cold climate chamber. The material is a common material used to manufacture rotor blades of wind turbines. The temperature range is 25°C to -25°C and effects of temperature variations on amplitude and phase shift of the received signal are investigated. In order to apply the effects of lowering the temperature on the received signal, the Baseline Signal Stretch (BSS) method is modified and used. The modification is based on decomposing the signal into symmetric and asymmetric modes and applying two different stretch factors on each of them. Finally the results obtained based on the new method is compared with the results of application of BSS with one stretch factor and experimental measurements. Comparisons show that an improvement is obtained using the BSS with the mode decomposition method at temperature variations of more than 25°C.

  20. Variation in Differential and Total Cross Sections Due to Different Radial Wave Functions

    ERIC Educational Resources Information Center

    Williamson, W., Jr.; Greene, T.

    1976-01-01

    Three sets of analytical wave functions are used to calculate the Na (3s---3p) transition differential and total electron excitation cross sections by Born approximations. Results show expected large variations in values. (Author/CP)

  1. Seismic Waves, 4th order accurate

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    2013-08-16

    SW4 is a program for simulating seismic wave propagation on parallel computers. SW4 colves the seismic wave equations in Cartesian corrdinates. It is therefore appropriate for regional simulations, where the curvature of the earth can be neglected. SW4 implements a free surface boundary condition on a realistic topography, absorbing super-grid conditions on the far-field boundaries, and a kinematic source model consisting of point force and/or point moment tensor source terms. SW4 supports a fully 3-D heterogeneous material model that can be specified in several formats. SW4 can output synthetic seismograms in an ASCII test format, or in the SAC finarymore » format. It can also present simulation information as GMT scripts, whixh can be used to create annotated maps. Furthermore, SW4 can output the solution as well as the material model along 2-D grid planes.« less

  2. A physical model study of converted wave amplitude variation in a reservoir of systematically aligned vertical fractures

    NASA Astrophysics Data System (ADS)

    Chang, C.; Sun, L.; Lin, C.; Chang, Y.; Tseng, P.

    2013-12-01

    The existence of fractures not only provides spaces for the residence of oils and gases reside, but it also creates pathways for migration. Characterizing a fractured reservoir thus becomes an important subject and has been widely studied by exploration geophysicists and drilling engineers. In seismic anisotropy, a reservoir of systematically aligned vertical fractures (SAVF) is often treated as a transversely isotropic medium (TIM) with a horizontal axis of symmetry (HTI). Subjecting to HTI, physical properties vary in azimuth. P-wave reflection amplitude, which is susceptible to vary in azimuth, is one of the most popular seismic attributes which is widely used to delineate the fracture strike of an SAVF reservoir. Instead of going further on analyzing P-wave signatures, in this study, we focused on evaluating the feasibility of orienting the fracture strike of an SAVF reservoir using converted (C-) wave amplitude. For a C-wave is initiated by a downward traveling P-wave that is converted on reflection to an upcoming S-wave; the behaviors of both P- and S-waves should be theoretically woven in a C-wave. In our laboratory work, finite offset reflection experiments were carried out on the azimuthal plane of a HTI model at two different offset intervals. To demonstrate the azimuthal variation of C-wave amplitude in a HTI model, reflections were acquired along the principal symmetry directions and the diagonal direction of the HTI model. Inheriting from phenomenon of S-wave splitting in a transversely isotropic medium (TIM), P-waves get converted into both the fast (S1) and slow (S2) shear modes at all azimuths outside the vertical symmetry planes, thus producing split PS-waves (PS1 and PS2). In our laboratory data, the converted PS1- (C1-) wave were observed and identified. As the azimuth varies from the strike direction to the strike normal, C1-wave amplitude exhibits itself in a way of weakening and can be view from the common-reflection-point (CRP) gathers

  3. FAST TRACK COMMUNICATION Accurate estimate of α variation and isotope shift parameters in Na and Mg+

    NASA Astrophysics Data System (ADS)

    Sahoo, B. K.

    2010-12-01

    We present accurate calculations of fine-structure constant variation coefficients and isotope shifts in Na and Mg+ using the relativistic coupled-cluster method. In our approach, we are able to discover the roles of various correlation effects explicitly to all orders in these calculations. Most of the results, especially for the excited states, are reported for the first time. It is possible to ascertain suitable anchor and probe lines for the studies of possible variation in the fine-structure constant by using the above results in the considered systems.

  4. The detection of T-wave variation linked to arrhythmic risk: an industry perspective.

    PubMed

    Xue, Joel; Rowlandson, Ian

    2013-01-01

    Although the scientific literature contains ample descriptions of peculiar patterns of repolarization linked to arrhythmic risk, the objective quantification and classification of these patterns continues to be a challenge that impacts their widespread adoption in clinical practice. To advance the science, computerized algorithms spawned in the academic environment have been essential in order to find, extract and measure these patterns. However, outside the strict control of a core lab, these algorithms are exposed to poor quality signals and need to be effective in the presence of different forms of noise that can either obscure or mimic the T-wave variation (TWV) of interest. To provide a practical solution that can be verified and validated for the market, important tradeoffs need to be made that are based on an intimate understanding of the end-user as well as the key characteristics of either the signal or the noise that can be used by the signal processing engineer to best differentiate them. To illustrate this, two contemporary medical devices used for quantifying T-wave variation are presented, including the modified moving average (MMA) for the detection of T-wave Alternans (TWA) and the quantification of T-wave shape as inputs to the Morphology Combination Score (MCS) for the trending of drug-induced repolarization abnormalities. © 2013 Elsevier Inc. All rights reserved.

  5. Effects of the magnetic field variation on the spin wave interference in a magnetic cross junction

    NASA Astrophysics Data System (ADS)

    Balynskiy, M.; Chiang, H.; Kozhevnikov, A.; Dudko, G.; Filimonov, Y.; Balandin, A. A.; Khitun, A.

    2018-05-01

    This article reports results of the investigation of the effect of the external magnetic field variation on the spin wave interference in a magnetic cross junction. The experiments were performed using a micrometer scale Y3Fe5O12 cross structure with a set of micro-antennas fabricated on the edges of the cross arms. Two of the antennas were used for the spin wave excitation while a third antenna was used for detecting the inductive voltage produced by the interfering spin waves. It was found that a small variation of the bias magnetic field may result in a significant change of the output inductive voltage. The effect is most prominent under the destructive interference condition. The maximum response exceeds 30 dB per 0.1 Oe at room temperature. It takes a relatively small bias magnetic field variation of about 1 Oe to drive the system from the destructive to the constructive interference conditions. The switching is accompanied by a significant, up to 50 dB, change in the output voltage. The obtained results demonstrate a feasibility of the efficient spin wave interference control by an external magnetic field, which may be utilized for engineering novel type of magnetometers and magnonic logic devices.

  6. Highly accurate symplectic element based on two variational principles

    NASA Astrophysics Data System (ADS)

    Qing, Guanghui; Tian, Jia

    2018-02-01

    For the stability requirement of numerical resultants, the mathematical theory of classical mixed methods are relatively complex. However, generalized mixed methods are automatically stable, and their building process is simple and straightforward. In this paper, based on the seminal idea of the generalized mixed methods, a simple, stable, and highly accurate 8-node noncompatible symplectic element (NCSE8) was developed by the combination of the modified Hellinger-Reissner mixed variational principle and the minimum energy principle. To ensure the accuracy of in-plane stress results, a simultaneous equation approach was also suggested. Numerical experimentation shows that the accuracy of stress results of NCSE8 are nearly the same as that of displacement methods, and they are in good agreement with the exact solutions when the mesh is relatively fine. NCSE8 has advantages of the clearing concept, easy calculation by a finite element computer program, higher accuracy and wide applicability for various linear elasticity compressible and nearly incompressible material problems. It is possible that NCSE8 becomes even more advantageous for the fracture problems due to its better accuracy of stresses.

  7. Predicting location-specific extreme coastal floods in the future climate by introducing a probabilistic method to calculate maximum elevation of the continuous water mass caused by a combination of water level variations and wind waves

    NASA Astrophysics Data System (ADS)

    Leijala, Ulpu; Björkqvist, Jan-Victor; Johansson, Milla M.; Pellikka, Havu

    2017-04-01

    Future coastal management continuously strives for more location-exact and precise methods to investigate possible extreme sea level events and to face flooding hazards in the most appropriate way. Evaluating future flooding risks by understanding the behaviour of the joint effect of sea level variations and wind waves is one of the means to make more comprehensive flooding hazard analysis, and may at first seem like a straightforward task to solve. Nevertheless, challenges and limitations such as availability of time series of the sea level and wave height components, the quality of data, significant locational variability of coastal wave height, as well as assumptions to be made depending on the study location, make the task more complicated. In this study, we present a statistical method for combining location-specific probability distributions of water level variations (including local sea level observations and global mean sea level rise) and wave run-up (based on wave buoy measurements). The goal of our method is to obtain a more accurate way to account for the waves when making flooding hazard analysis on the coast compared to the approach of adding a separate fixed wave action height on top of sea level -based flood risk estimates. As a result of our new method, we gain maximum elevation heights with different return periods of the continuous water mass caused by a combination of both phenomena, "the green water". We also introduce a sensitivity analysis to evaluate the properties and functioning of our method. The sensitivity test is based on using theoretical wave distributions representing different alternatives of wave behaviour in relation to sea level variations. As these wave distributions are merged with the sea level distribution, we get information on how the different wave height conditions and shape of the wave height distribution influence the joint results. Our method presented here can be used as an advanced tool to minimize over- and

  8. Wave behaviour of sporadic E-layer variations at the latitudes 30-70N

    NASA Astrophysics Data System (ADS)

    Ryabchenko, E. Yu.; Sherstyukov, O. N.

    A wave behaviour of sporadic E-layer variations was investigated by analysing time series of twenty European ionosonde stations (30°N--80°N, 15°W--45°E) for 1985-1988. Wavelet transform was used to explore 3-30 periodicities in variations of Es-layer relative electron density δ NEs defined here as (foEs2--foE2)/foE2. Such compound parameter allowed us to partly exclude solar ionisation factor and concentrate on meteorological nature of Es-layer synoptical oscillations. A typical synoptical atmospheric 3-30 day oscillations were discovered in foEs and also in δ NEs. Due to nonorthgonal wavelet transform used in this work, it is advisable to divide frequency domain into several optimal intervals. Five periods 4,6,10,16 and 24 day were chosen which cover 3-5, 5-7, 8-12, 13-20 and 20-30 day intervals. Low value of oscillation amplitude not greater than 1.5 is typical for most of European ionospheric stations in January-March and September-December. A higher values were observed at latitudes higher than 60°N. A wave vortex were discovered during the analysis of dynamics of δ NEs spatio-temporal variations in summer for each period interval. In May and June we observed wave penetration from north and south into the middle latitudes 45°N--55°N with amplitudes up to 5.0 for the most of considered years. In Jule and August all amplitudes reach their average values.

  9. A model for seasonal changes in GPS positions and seismic wave speeds due to thermoelastic and hydrologic variations

    USGS Publications Warehouse

    Tsai, V.C.

    2011-01-01

    It is known that GPS time series contain a seasonal variation that is not due to tectonic motions, and it has recently been shown that crustal seismic velocities may also vary seasonally. In order to explain these changes, a number of hypotheses have been given, among which thermoelastic and hydrology-induced stresses and strains are leading candidates. Unfortunately, though, since a general framework does not exist for understanding such seasonal variations, it is currently not possible to quickly evaluate the plausibility of these hypotheses. To fill this gap in the literature, I generalize a two-dimensional thermoelastic strain model to provide an analytic solution for the displacements and wave speed changes due to either thermoelastic stresses or hydrologic loading, which consists of poroelastic stresses and purely elastic stresses. The thermoelastic model assumes a periodic surface temperature, and the hydrologic models similarly assume a periodic near-surface water load. Since all three models are two-dimensional and periodic, they are expected to only approximate any realistic scenario; but the models nonetheless provide a quantitative framework for estimating the effects of thermoelastic and hydrologic variations. Quantitative comparison between the models and observations is further complicated by the large uncertainty in some of the relevant parameters. Despite this uncertainty, though, I find that maximum realistic thermoelastic effects are unlikely to explain a large fraction of the observed annual variation in a typical GPS displacement time series or of the observed annual variations in seismic wave speeds in southern California. Hydrologic loading, on the other hand, may be able to explain a larger fraction of both the annual variations in displacements and seismic wave speeds. Neither model is likely to explain all of the seismic wave speed variations inferred from observations. However, more definitive conclusions cannot be made until the model

  10. Hurricane Directional Wave Spectrum Spatial Variation in the Open Ocean and at Landfall

    NASA Technical Reports Server (NTRS)

    Walsh, Edward J.; Wright, C. Wayne; Vandemark, Douglas C.; Krabill, William B.; Garcia, Andrew W.; Houston, Samuel H.; Powell, Mark D.; Black, Peter G.; Marks, Frank D.

    2000-01-01

    The sea surface directional wave spectrum was measured for the first time in all quadrants of a hurricane in open water using the NASA airborne scanning radar altimeter (SRA) carried aboard one of the NOAA WP-3D hurricane hunter aircraft at 1.5 km height. The SRA measures the energetic portion of the directional wave spectrum by generating a topographic map of the sea surface. At 8 Hz, the SRA sweeps a radar beam of 1' half-power width (two-way) across the aircraft ground track over a swath equal to 0.8 of the aircraft height, simultaneously measuring the backscattered power at its 36 GHz (8.3 mm) operating frequency and the range to the sea surface at 64 positions. These slant ranges are multiplied by the cosine of the off-nadir angles to determine the vertical distances from the aircraft to the sea surface. Subtracting these distances from the aircraft height produces the sea surface elevation map. The sea surface topography is interpolated to a uniform grid, transformed by a two dimensional FFT, and Doppler corrected. The open-ocean data were acquired on 24 August 1998 when hurricane Bonnie was east of the Bahamas and moving toward 330 deg at about 5 m/s. Individual waves up to 18 m height were observed and the spatial variation of the wave field was dramatic. The dominant waves generally propagated at significant angles to the downwind direction. At some positions there were three different wave fields of comparable energy crossing each other. The NOAA aircraft spent over five hours within 180 km of the eye, and made five eye penetrations. On 26 August 1998, the NOAA aircraft flew at 2.2 km height when hurricane Bonnie was making landfall near Wilmington, NC, documenting the directional wave spectrum in the region between Charleston, SC and Cape Hatteras, NC. The aircraft flight lines included segments near and along the shoreline as well as far offshore. Animations of the directional wave spectrum spatial variation along the aircraft tracks on the two flights

  11. Projection of heat waves variation over a warming climate in China

    NASA Astrophysics Data System (ADS)

    Yue, X.; Wu, S.; Pan, T.

    2016-12-01

    Heat waves (HW) have adverse impacts on economies, human health, societies and environment, which have been observed around the world and are expected to increase in a warming climate. However, the variations of HW under climate change over China are not clear yet. Using the HadGEM2-ES RCP4.5 and RCP8.5 daily maximum temperature and humidity dataset, variation of heat waves in China for 2021-2050 comparing to 1991-2000 as baseline were analyzed. The CMA-HI (Heat Index standardized by China Meteorological Administration) index was used to calculate the frequency and intensity of head waves. This paper classified the HW into three intensity levels including mild HW, moderate HW and severe HW , and defined a heat wave event (HWE) as that CMA-HI are all above or equal to 2.8 and keep at a intensity level more than five consecutive days. Results show that during 2021to 2050, the distribution area, frequency and duration of each intensity level have an increasing trend over China, and those of severe HW will increase mostly. The distribution area of mild, moderate and severe HW will increase 18%, 22%, 35% respectively. Average HWE frequency of each level will concentrate on 0.5-1instead of 0-0.3 in baseline period. Maximum frequency of each intensity can reach to almost 3 times a year. During 1991-2000, the average frequency of mild HW, moderate HW and severe HW kept a downward sequence. But it will change to increase in the future, and the shift occurs during 2031-2040. In addition, only severe HW duration will increase in the future. Its average value will increase from 9days to 13days, and keep a maximum duration of 42days.While the average duration of mild HW and moderate HW just keep almost 6 days and 8 days as usual. Regionally, both the frequency and duration will keep high value in the region of eastern China, central China, southern China and central Xinjiang autonomous region in the future. And only severe HW has a great change in distribution. Under RCP 8

  12. Gravity waves in Titan's atmosphere

    NASA Technical Reports Server (NTRS)

    Friedson, A. James

    1994-01-01

    Scintillations (high frequency variations) observed in the radio signal during the occultation of Voyager 1 by Titan (Hinson and Tyler, 1983) provide information concerning neutral atmospheric density fluctuations on scales on hundreds of meters to a few kilometers. Those seen at altitudes higher than 25 km above the surface were interpreted by Hinson and Tyler as being caused by linear, freely propagating (energy-conserving) gravity waves, but this interpretation was found to be inconsistent with the scintillation data below the 25-km altitude level. Here an attempt is made to interpret the entire scintillation profile between the surface and the 90-km altitude level in terms of gravity waves generated at the surface. Numerical calculations of the density fluctuations caused by two-dimensional, nonhydrostatic, finite-amplitude gravity waves propagating vertically through Titan's atmosphere are performed to produce synthetic scintillation profiles for comparison with the observations. The numerical model accurately treats the effects of wave transience, nonlinearity, and breakdown due to convective instability in the overturned part of the wave. The high-altitude scintillation data were accurately recovered with a freely propagating wave solution, confirming the analytic model of Hinson and Tyler. It is found that the low-altitude scintillation data can be fit by a model where a component of the gravity waves becomes convectively unstable and breaks near the 15 km level. The large-scale structure of the observed scintillation profile in the entire altitude range between 5 and 85 km can be simulated by a model where the freely propagating and breaking waves are forced at the surface simultaneously. Further analysis of the Voyager 1 Titan low-altitude scintillation data, using inversion theory appropriate for strong scattering, could potentially remove some of the ambiguities remaining in this analysis and allow a better determination of the strength and source of

  13. Longitudinal Variation and Waves in Jupiter's South Equatorial Wind Jet

    NASA Technical Reports Server (NTRS)

    Simon-Miller, Amy A.; Choi, David; Rogers, John H.; Gierasch, Peter J.; Allison, Michael D.; Adamoli, Gianluigi; Mettig, Hans-Joerg

    2012-01-01

    A detailed study of the chevron-shaped dark spots on the strong southern equatorial wind jet near 7.5 S planetographic latitude shows variations in velocity with longitude and time. The presence of the large anticyclonic South Equatorial Disturbance (SED) has a profound effect on the chevron velocity, causing slower velocities to its east and accelerations over distance from the disturbance. The chevrons move with velocities near the maximum wind jet velocity of approx 140 m/s, as deduced by the history of velocities at this latitude and the magnitude of the symmetric wind jet near 7 N latitude. Their repetitive nature is consistent with a gravity-inertia wave (n = 75 to 100) with phase speed up to 25 m/s, relative to the local flow, but the identity of this wave mode is not well constrained. However, for the first time, high spatial resolution movies from Cassini images show that the chevrons oscillate in latitude with a 6.7 +/- 0.7-day period. This oscillating motion has a wavelength of approx 20 and a speed of 101 +/- 3 m/s, following a pattern similar to that seen in the Rossby wave plumes of the North Equatorial Zone, and possibly reinforced by it. All dates show chevron latitude variability, but it is unclear if this larger wave is present during other epochs, as there are no other suitable time series movies that fully delineate it. In the presence of mUltiple wave modes, the difference in dominant cloud appearance between 7 deg N and 7.5 deg S is likely due to the presence of the Great Red Spot, either through changes in stratification and stability or by acting as a wave boundary.

  14. Wave groupiness variations in the nearshore

    USGS Publications Warehouse

    List, J.H.

    1991-01-01

    This paper proposes a new definition of the groupiness factor, GF, based on the envelope of the incident-wave time series. It is shown that an envelope-based GF has several important advantages over the SIWEH-based groupiness factor, including objective criteria for determining the accuracy of the envelope function and well-defined numerical limits. Using this new GF, the variability of incident wave groupiness in the field is examined both temporally, in unbroken waves at a fixed location, and spatially, in a cross-shore array through the surf zone. Contrary to previous studies using the SIWEH-based GF, results suggest that incident wave groupiness may not be an independent parameter in unbroken waves; through a wide range of spectral shapes, from swell to storm waves, the groupiness did not vary significantly. As expected, the groupiness decreases rapidly as waves break through the surf zone, although significant wave height variability persists even through a saturated surf zone. The source of this inner surf zone groupiness is not identified; however, this observation implies that models of long wave generation must account for nonsteady radiation stress gradients landward of some narrow zone near the mean breakpoint. ?? 1991.

  15. Variational approach to studying solitary waves in the nonlinear Schrödinger equation with complex potentials

    DOE PAGES

    Mertens, Franz G.; Cooper, Fred; Arevalo, Edward; ...

    2016-09-15

    Here in this paper, we discuss the behavior of solitary wave solutions of the nonlinear Schrödinger equation (NLSE) as they interact with complex potentials, using a four-parameter variational approximation based on a dissipation functional formulation of the dynamics. We concentrate on spatially periodic potentials with the periods of the real and imaginary part being either the same or different. Our results for the time evolution of the collective coordinates of our variational ansatz are in good agreement with direct numerical simulation of the NLSE. We compare our method with a collective coordinate approach of Kominis and give examples where themore » two methods give qualitatively different answers. In our variational approach, we are able to give analytic results for the small oscillation frequency of the solitary wave oscillating parameters which agree with the numerical solution of the collective coordinate equations. We also verify that instabilities set in when the slope dp(t)/dv(t) becomes negative when plotted parametrically as a function of time, where p(t) is the momentum of the solitary wave and v(t) the velocity.« less

  16. Variational approach to studying solitary waves in the nonlinear Schrödinger equation with complex potentials

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mertens, Franz G.; Cooper, Fred; Arevalo, Edward

    Here in this paper, we discuss the behavior of solitary wave solutions of the nonlinear Schrödinger equation (NLSE) as they interact with complex potentials, using a four-parameter variational approximation based on a dissipation functional formulation of the dynamics. We concentrate on spatially periodic potentials with the periods of the real and imaginary part being either the same or different. Our results for the time evolution of the collective coordinates of our variational ansatz are in good agreement with direct numerical simulation of the NLSE. We compare our method with a collective coordinate approach of Kominis and give examples where themore » two methods give qualitatively different answers. In our variational approach, we are able to give analytic results for the small oscillation frequency of the solitary wave oscillating parameters which agree with the numerical solution of the collective coordinate equations. We also verify that instabilities set in when the slope dp(t)/dv(t) becomes negative when plotted parametrically as a function of time, where p(t) is the momentum of the solitary wave and v(t) the velocity.« less

  17. Systematic Convergence in Applying Variational Method to Double-Well Potential

    ERIC Educational Resources Information Center

    Mei, Wai-Ning

    2016-01-01

    In this work, we demonstrate the application of the variational method by computing the ground- and first-excited state energies of a double-well potential. We start with the proper choice of the trial wave functions using optimized parameters, and notice that accurate expectation values in excellent agreement with the numerical results can be…

  18. Variational mode decomposition based approach for accurate classification of color fundus images with hemorrhages

    NASA Astrophysics Data System (ADS)

    Lahmiri, Salim; Shmuel, Amir

    2017-11-01

    Diabetic retinopathy is a disease that can cause a loss of vision. An early and accurate diagnosis helps to improve treatment of the disease and prognosis. One of the earliest characteristics of diabetic retinopathy is the appearance of retinal hemorrhages. The purpose of this study is to design a fully automated system for the detection of hemorrhages in a retinal image. In the first stage of our proposed system, a retinal image is processed with variational mode decomposition (VMD) to obtain the first variational mode, which captures the high frequency components of the original image. In the second stage, four texture descriptors are extracted from the first variational mode. Finally, a classifier trained with all computed texture descriptors is used to distinguish between images of healthy and unhealthy retinas with hemorrhages. Experimental results showed evidence of the effectiveness of the proposed system for detection of hemorrhages in the retina, since a perfect detection rate was achieved. Our proposed system for detecting diabetic retinopathy is simple and easy to implement. It requires only short processing time, and it yields higher accuracy in comparison with previously proposed methods for detecting diabetic retinopathy.

  19. Gaussian variational ansatz in the problem of anomalous sea waves: Comparison with direct numerical simulation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ruban, V. P., E-mail: ruban@itp.ac.ru

    2015-05-15

    The nonlinear dynamics of an obliquely oriented wave packet on a sea surface is analyzed analytically and numerically for various initial parameters of the packet in relation to the problem of the so-called rogue waves. Within the Gaussian variational ansatz applied to the corresponding (1+2)-dimensional hyperbolic nonlinear Schrödinger equation (NLSE), a simplified Lagrangian system of differential equations is derived that describes the evolution of the coefficients of the real and imaginary quadratic forms appearing in the Gaussian. This model provides a semi-quantitative description of the process of nonlinear spatiotemporal focusing, which is one of the most probable mechanisms of roguemore » wave formation in random wave fields. The system of equations is integrated in quadratures, which allows one to better understand the qualitative differences between linear and nonlinear focusing regimes of a wave packet. Predictions of the Gaussian model are compared with the results of direct numerical simulation of fully nonlinear long-crested waves.« less

  20. Accurate Time-Dependent Traveling-Wave Tube Model Developed for Computational Bit-Error-Rate Testing

    NASA Technical Reports Server (NTRS)

    Kory, Carol L.

    2001-01-01

    The phenomenal growth of the satellite communications industry has created a large demand for traveling-wave tubes (TWT's) operating with unprecedented specifications requiring the design and production of many novel devices in record time. To achieve this, the TWT industry heavily relies on computational modeling. However, the TWT industry's computational modeling capabilities need to be improved because there are often discrepancies between measured TWT data and that predicted by conventional two-dimensional helical TWT interaction codes. This limits the analysis and design of novel devices or TWT's with parameters differing from what is conventionally manufactured. In addition, the inaccuracy of current computational tools limits achievable TWT performance because optimized designs require highly accurate models. To address these concerns, a fully three-dimensional, time-dependent, helical TWT interaction model was developed using the electromagnetic particle-in-cell code MAFIA (Solution of MAxwell's equations by the Finite-Integration-Algorithm). The model includes a short section of helical slow-wave circuit with excitation fed by radiofrequency input/output couplers, and an electron beam contained by periodic permanent magnet focusing. A cutaway view of several turns of the three-dimensional helical slow-wave circuit with input/output couplers is shown. This has been shown to be more accurate than conventionally used two-dimensional models. The growth of the communications industry has also imposed a demand for increased data rates for the transmission of large volumes of data. To achieve increased data rates, complex modulation and multiple access techniques are employed requiring minimum distortion of the signal as it is passed through the TWT. Thus, intersymbol interference (ISI) becomes a major consideration, as well as suspected causes such as reflections within the TWT. To experimentally investigate effects of the physical TWT on ISI would be

  1. Depth variations of P-wave azimuthal anisotropy beneath East Asia

    NASA Astrophysics Data System (ADS)

    Wei, W.; Zhao, D.; Xu, J.

    2017-12-01

    We present a new P-wave anisotropic tomographic model beneath East Asia by inverting a total of 1,488,531 P wave arrival-time data recorded by the regional seismic networks in East Asia and temporary seismic arrays deployed on the Tibetan Plateau. Our results provide important new insights into the subducting Indian, Pacific and Philippine Sea plates and mantle dynamics in East Asia. Our tomographic images show that the northern limit of the subducting Indian plate has reached the Jinsha River suture in eastern Tibet. A striking variation of P-wave azimuthal anisotropy is revealed in the Indian lithosphere: the fast velocity direction (FVD) is NE-SW beneath the Indian continent, whereas the FVD is arc parallel beneath the Himalaya and Tibetan Plateau, which may reflect re-orientation of minerals due to lithospheric extension, in response to the India-Eurasia collision. The FVD in the subducting Philippine Sea plate beneath the Ryukyu arc is NE-SW(trench parallel), which is consistent with the spreading direction of the West Philippine Basin during its initial opening stage, suggesting that it may reflect the fossil anisotropy. A circular pattern of FVDs is revealed around the Philippine Sea slab beneath SE China. We suggest that it reflects asthenospheric strain caused by toroidal mantle flow around the edge of the subducting slab. We find a striking variation of the FVD with depth in the subducting Pacific slab beneath the Northeast Japan arc. It may be caused by slab dehydration that changed elastic properties of the slab with depth. The FVD in the mantle wedge beneath the Northeast Japan and Ryukyu arcs is trench normal, which reflects subduction-induced convection. Beneath the Kuril and Izu-Bonin arcs where oblique subduction occurs, the FVD in the mantle wedge is nearly normal to the moving direction of the downgoing Pacific plate, suggesting that the oblique subduction together with the complex slab morphology have disturbed the mantle flow.

  2. Kinetic Alfven wave with density variation and loss-cone distribution function of multi-ions in PSBL region

    NASA Astrophysics Data System (ADS)

    Tamrakar, Radha; Varma, P.; Tiwari, M. S.

    2018-05-01

    Kinetic Alfven wave (KAW) generation due to variation of loss-cone index J and density of multi-ions (H+, He+ and O+) in the plasma sheet boundary layer region (PSBL) is investigated. Kinetic approach is used to derive dispersion relation of wave using Vlasov equation. Variation of frequency with respect to wide range of k⊥ρi (where k⊥ is wave vector across the magnetic field, ρi is gyroradius of ions and i denotes H+, He+ and O+ ions) is analyzed. It is found that each ion gyroradius and number density shows different effect on wave generation with varying width of loss-cone. KAW is generated with multi-ions (H+, He+ and O+) over wide regime for J=1 and shows dissimilar effect for J=2. Frequency is reduced with increasing density of gyrating He+ and O+ ions. Wave frequency is obtained within the reported range which strongly supports generation of kinetic Alfven waves. A sudden drop of frequency is also observed for H+ and He+ ion which may be due to heavy penetration of these ions through the loss-cone. The parameters of PSBL region are used for numerical calculation. The application of these results are in understanding the effect of gyrating multi-ions in transfer of energy and Poynting flux losses from PSBL region towards ionosphere and also describing the generation of aurora.

  3. Physiological variation in left atrial transverse orientation does not influence orthogonal P-wave morphology.

    PubMed

    Petersson, Richard; Mosén, Henrik; Steding-Ehrenborg, Katarina; Carlson, Jonas; Faxén, Lisa; Mohtadi, Alan; Platonov, Pyotr G; Holmqvist, Fredrik

    2017-03-01

    It has previously been demonstrated that orthogonal P-wave morphology in healthy athletes does not depend on atrial size, but the possible impact of left atrial orientation on P-wave morphology remains unknown. In this study, we investigated if left atrial transverse orientation affects P-wave morphology in different populations. Forty-seven patients with atrial fibrillation, 21 patients with arrhythmogenic right ventricular cardiomyopathy, 67 healthy athletes, and 56 healthy volunteers were included. All underwent cardiac magnetic resonance imaging or computed tomography and the orientation of the left atrium was determined. All had 12-lead electrocardiographic recordings, which were transformed into orthogonal leads and orthogonal P-wave morphology was obtained. The median left atrial transverse orientation was 87 (83, 91) degrees (lower and upper quartiles) in the total study population. There was no difference in left atrial transverse orientation between individuals with different orthogonal P-wave morphologies. The physiological variation in left atrial orientation was small within as well as between the different populations. There was no difference in left atrial transverse orientation between subjects with type 1 and type 2 P-wave morphology, implying that in this setting the P-wave morphology was more dependent on atrial conduction than orientation. © 2016 Wiley Periodicals, Inc.

  4. Mixed sand and gravel beaches: accurate measurement of active layer depth and sediment transport volumes using PIT tagged tracer pebbles

    NASA Astrophysics Data System (ADS)

    Holland, A.; Moses, C.; Sear, D. A.; Cope, S.

    2016-12-01

    As sediments containing significant gravel portions are increasingly used for beach replenishment projects globally, the total number of beaches classified as `mixed sand and gravel' (MSG) increases. Calculations for required replenishment sediment volumes usually assume a uniform layer of sediment transport across and along the beach, but research into active layer (AL) depth has shown variations both across shore and according to sediment size distribution. This study addresses the need for more accurate calculations of sediment transport volumes on MSG beaches by using more precise measurements of AL depth and width, and virtual velocity of tracer pebbles. Variations in AL depth were measured along three main profile lines (from MHWS to MLWN) at Eastoke, Hayling Island (Hampshire, UK). Passive Integrated Transponder (PIT) tagged pebbles were deployed in columns, and their new locations repeatedly surveyed with RFID technology. These data were combined with daily dGPS beach profiles and sediment sampling for detailed analysis of the influence of beach morphodynamics on sediment transport volumes. Data were collected over two consecutive winter seasons: 2014-15 (relatively calm, average wave height <1 m) and 2015-16 (prolonged periods of moderate storminess, wave heights of 1-2 m). The active layer was, on average, 22% of wave height where beach slope (tanβ) is 0.1, with variations noted according to slope angle, sediment distribution, and beach groundwater level. High groundwater levels and a change in sediment proportions in the sandy lower foreshore reduced the AL to 10% of wave height in this area. The disparity in AL depth across the beach profile indicates that traditional models are not accurately representing bulk sediment transport on MSG beaches. It is anticipated that by improving model inputs, beach managers will be better able to predict necessary volumes and sediment grain size proportions of replenishment material for effective management of MSG

  5. Accurate Drift Time Determination by Traveling Wave Ion Mobility Spectrometry: The Concept of the Diffusion Calibration.

    PubMed

    Kune, Christopher; Far, Johann; De Pauw, Edwin

    2016-12-06

    Ion mobility spectrometry (IMS) is a gas phase separation technique, which relies on differences in collision cross section (CCS) of ions. Ionic clouds of unresolved conformers overlap if the CCS difference is below the instrumental resolution expressed as CCS/ΔCCS. The experimental arrival time distribution (ATD) peak is then a superimposition of the various contributions weighted by their relative intensities. This paper introduces a strategy for accurate drift time determination using traveling wave ion mobility spectrometry (TWIMS) of poorly resolved or unresolved conformers. This method implements through a calibration procedure the link between the peak full width at half-maximum (fwhm) and the drift time of model compounds for wide range of settings for wave heights and velocities. We modified a Gaussian equation, which achieves the deconvolution of ATD peaks where the fwhm is fixed according to our calibration procedure. The new fitting Gaussian equation only depends on two parameters: The apex of the peak (A) and the mean drift time value (μ). The standard deviation parameter (correlated to fwhm) becomes a function of the drift time. This correlation function between μ and fwhm is obtained using the TWIMS calibration procedure which determines the maximum instrumental ion beam diffusion under limited and controlled space charge effect using ionic compounds which are detected as single conformers in the gas phase. This deconvolution process has been used to highlight the presence of poorly resolved conformers of crown ether complexes and peptides leading to more accurate CCS determinations in better agreement with quantum chemistry predictions.

  6. Prompt Disappearance and Emergence of Radiation Belt Magnetosonic Waves Induced by Solar Wind Dynamic Pressure Variations

    NASA Astrophysics Data System (ADS)

    Liu, Nigang; Su, Zhenpeng; Zheng, Huinan; Wang, Yuming; Wang, Shui

    2018-01-01

    Magnetosonic waves are highly oblique whistler mode emissions transferring energy from the ring current protons to the radiation belt electrons in the inner magnetosphere. Here we present the first report of prompt disappearance and emergence of magnetosonic waves induced by the solar wind dynamic pressure variations. The solar wind dynamic pressure reduction caused the magnetosphere expansion, adiabatically decelerated the ring current protons for the Bernstein mode instability, and produced the prompt disappearance of magnetosonic waves. On the contrary, because of the adiabatic acceleration of the ring current protons by the solar wind dynamic pressure enhancement, magnetosonic waves emerged suddenly. In the absence of impulsive injections of hot protons, magnetosonic waves were observable even only during the time period with the enhanced solar wind dynamic pressure. Our results demonstrate that the solar wind dynamic pressure is an essential parameter for modeling of magnetosonic waves and their effect on the radiation belt electrons.

  7. Understanding the variation in the millimeter-wave emission of Venus

    NASA Technical Reports Server (NTRS)

    Fahd, Antoine K.; Steffes, Paul G.

    1992-01-01

    Recent observations of the millimeter-wave emission from Venus at 112 GHz (2.6 mm) have shown significant variations in the continuum flux emission that may be attributed to the variability in the abundances of absorbing constituents in the Venus atmosphere. Such constituents include gaseous H2SO4, SO2, and liquid sulfuric acid (cloud condensates). Recently, Fahd and Steffes have shown that the effects of liquid H, SO4, and gaseous SO2 cannot completely account for this measured variability in the millimeter-wave emission of Venus. Thus, it is necessary to study the effect of gaseous H2SO4 on the millimeter-wave emission of Venus. This requires knowledge of the millimeter-wavelength (MMW) opacity of gaseous H2SO4, which unfortunately has never been determined for Venus-like conditions. We have measured the opacity of gaseous H2SO4 in a CO2 atmosphere at 550, 570, and 590 K, at 1 and 2 atm total pressure, and at a frequency of 94.1 GHz. Our results, in addition to previous centimeter-wavelength results are used to verify a modeling formalism for calculating the expected opacity of this gaseous mixture at other frequencies. This formalism is incorporated into a radiative transfer model to study the effect of gaseous H2SO4 on the MMW emission of Venus.

  8. Accurate source location from waves scattered by surface topography: Applications to the Nevada and North Korean test sites

    NASA Astrophysics Data System (ADS)

    Shen, Y.; Wang, N.; Bao, X.; Flinders, A. F.

    2016-12-01

    Scattered waves generated near the source contains energy converted from the near-field waves to the far-field propagating waves, which can be used to achieve location accuracy beyond the diffraction limit. In this work, we apply a novel full-wave location method that combines a grid-search algorithm with the 3D Green's tensor database to locate the Non-Proliferation Experiment (NPE) at the Nevada test site and the North Korean nuclear tests. We use the first arrivals (Pn/Pg) and their immediate codas, which are likely dominated by waves scattered at the surface topography near the source, to determine the source location. We investigate seismograms in the frequency of [1.0 2.0] Hz to reduce noises in the data and highlight topography scattered waves. High resolution topographic models constructed from 10 and 90 m grids are used for Nevada and North Korea, respectively. The reference velocity model is based on CRUST 1.0. We use the collocated-grid finite difference method on curvilinear grids to calculate the strain Green's tensor and obtain synthetic waveforms using source-receiver reciprocity. The `best' solution is found based on the least-square misfit between the observed and synthetic waveforms. To suppress random noises, an optimal weighting method for three-component seismograms is applied in misfit calculation. Our results show that the scattered waves are crucial in improving resolution and allow us to obtain accurate solutions with a small number of stations. Since the scattered waves depends on topography, which is known at the wavelengths of regional seismic waves, our approach yields absolute, instead of relative, source locations. We compare our solutions with those of USGS and other studies. Moreover, we use differential waveforms to locate pairs of the North Korea tests from years 2006, 2009, 2013 and 2016 to further reduce the effects of unmodeled heterogeneities and errors in the reference velocity model.

  9. Photoelectron wave function in photoionization: plane wave or Coulomb wave?

    PubMed

    Gozem, Samer; Gunina, Anastasia O; Ichino, Takatoshi; Osborn, David L; Stanton, John F; Krylov, Anna I

    2015-11-19

    The calculation of absolute total cross sections requires accurate wave functions of the photoelectron and of the initial and final states of the system. The essential information contained in the latter two can be condensed into a Dyson orbital. We employ correlated Dyson orbitals and test approximate treatments of the photoelectron wave function, that is, plane and Coulomb waves, by comparing computed and experimental photoionization and photodetachment spectra. We find that in anions, a plane wave treatment of the photoelectron provides a good description of photodetachment spectra. For photoionization of neutral atoms or molecules with one heavy atom, the photoelectron wave function must be treated as a Coulomb wave to account for the interaction of the photoelectron with the +1 charge of the ionized core. For larger molecules, the best agreement with experiment is often achieved by using a Coulomb wave with a partial (effective) charge smaller than unity. This likely derives from the fact that the effective charge at the centroid of the Dyson orbital, which serves as the origin of the spherical wave expansion, is smaller than the total charge of a polyatomic cation. The results suggest that accurate molecular photoionization cross sections can be computed with a modified central potential model that accounts for the nonspherical charge distribution of the core by adjusting the charge in the center of the expansion.

  10. Effects of the planetary-scale waves on the temporal variations of the O2-1.27μm nightglow in the Venusian upper atmosphere

    NASA Astrophysics Data System (ADS)

    Hoshino, N.; Fujiwara, H.; Takagi, M.; Kasaba, Y.; Takahashi, Y.

    2009-12-01

    The O2-1.27 μm nightglow distribution, which has the peak intensity in the depression region of the day-to-night flow, gives us information of the wind field at about 95 km in Venus. The past nightglow observations [Crisp et al., 1996] showed that the intensity of the nightglow in the brightness region changed by 20 % in about one hour, and the brightness region disappeared in less than one day. The observation results obtained by Venus Express (VEX) also showed the temporal variations of the nightglow emission. Some simulation studies suggested contributions of gravity waves generated in the cloud deck (50-70 km) to the temporal variations. However, the causes of the temporal variations are still unknown. In recent years, the importance of planetary-scale waves for the dynamics of the Venusian atmosphere has been recognized. For example, Takagi and Matsuda [2006] suggested that the atmospheric superrotation was driven by the momentum transport due to the vertical propagation of the thermal tides generated in the Venus cloud deck. In order to estimate effects of the planetary-scale waves on the temporal variations of the nightglow, we have performed numerical simulations with a general circulation model (GCM), which includes the altitude region of 80 - about 200 km. The planetary-scale waves (thermal tides, Kelvin wave and Rosbby wave) are imposed at the lower boundary. The amplitudes and phase velocities of the waves are assumed from the study by Del Genio and Rossow [1990]. The nightglow intensity and its global distribution are calculated from the GCM results assuming the chemical equilibration. In this study, we investigate contributions of the planetary-scale waves on the temporal variations of the nightglow shown by past observations. In addition, we show the characteristics of the wave propagation and the interactions between the waves in the Venusian upper atmosphere. Venus Climate Orbiter (VCO), which will be launched in 2010 as the second Japanese

  11. Diurnal Variation in Gravity Wave Activity at Low and Middle Latitudes

    NASA Technical Reports Server (NTRS)

    Andrioli, V. F.; Fritts, D. C.; Batista, P. P.; Clemesha, B. R.; Janches, Diego

    2013-01-01

    We employ a modified composite day extension of the Hocking (2005) analysis method to study gravity wave (GW) activity in the mesosphere and lower thermosphere using 4 meteor radars spanning latitudes from 7deg S to 53.6deg S. Diurnal and semidiurnal modulations were observed in GW variances over all sites. Semidiurnal modulation with downward phase propagation was observed at lower latitudes mainly near the equinoxes. Diurnal modulations occur mainly near solstice and, except for the zonal component at Cariri (7deg S), do not exhibit downward phase propagation. At a higher latitude (SAAMER, 53.6deg S) these modulations are only observed in the meridional component where we can observe diurnal variation from March to May, and semidiurnal, during January, February, October (above 88 km) and November. Some of these modulations with downward phase progression correlate well with wind shear. When the wind shear is well correlated with the maximum of the variances the diurnal tide has its largest amplitudes, i.e., near equinox. Correlations exhibiting variations with tidal phases suggest significant GW-tidal interactions that have different characters depending on the tidal components and possible mean wind shears. Modulations that do not exhibit phase variations could be indicative of diurnal variations in GW sources.

  12. Studies on Charge Variation and Waves in Dusty Plasmas

    NASA Astrophysics Data System (ADS)

    Kausik, Siddhartha Sankar

    Plasma and dust grains are both ubiquitous ingredients of the universe. The interplay between them has opened up a new and fascinating research domain, that of dusty plasmas, which contain macroscopic particles of solid matter besides the usual plasma constituents. The research in dusty plasmas received a major boost in the early eighties with Voyager spacecraft observation on the formation of Saturn rings. Dusty plasmas are defined as partially or fully-ionized gases that contain micron-sized particles of electrically charged solid material, either dielectric or conducting. The physics of dusty plasmas has recently been studied intensively because of its importance for a number of applications in space and laboratory plasmas. This thesis presents the experimental studies on charge variation and waves in dusty plasmas. The experimental observations are carried out in two different experimental devices. Three different sets of experiments are carried out in two different experimental devices. Three different sets of experiments are carried out to study the dust charge variation in a filament discharge argon plasma. The dust grains used in these experiments are grains of silver. In another get of experiment, dust acoustic waves are studied in a de glow discharge argon plasma. Alumina dust grains are sprinkled in this experiment. The diagnostic tools used in these experiments are Langmuir probe and Faraday cup. The instruments used in these experiments are electrometer, He-Ne laser and charge coupled device (CCD) camera. Langmuir probe is used to measure plasma parameters, while Faraday cup and electrometer are used to measure very low current (~pA) carried by a collimated dust beam. He-Ne laser illuminates the dust grains and CCD camera is used to capture the images of dust acoustic waves. Silver dust grains are produced in the dust chamber by gas-evaporation technique. Due to differential pressure maintained between the dust and plasma chambers, the dust grains move

  13. Echocardiographic nomograms for upper abdominal aorta Doppler systolic wave values and systo-diastolic diameters variations in children.

    PubMed

    Cantinotti, Massimiliano; Giordano, Raffaele; Corsini, Iuri; Dani, Carlo; Scalese, Marco; Murzi, Bruno; Assanta, Nadia; Spadoni, Isabella; Molinaro, Sabrina; Kutty, Shelby; Iervasi, Giorgio; Franchi, Eliana

    2018-04-01

    Abdominal aorta pulsatility and blood flow patterns are important diagnostic indicators in congenital heart disease. Reference values for these indexes are lacking. We prospectively studied abdominal aorta pulsed-wave Doppler systolic peak velocity, deceleration time, and wave duration, and two-dimensional vessel diameters in systole and diastole in healthy Caucasian children. Heteroscedasticity was accounted for by White or Breusch-Pagan test. Age, weight, height, heart rate (HR), and body surface area (BSA) were used as independent variables in different analyses to predict the mean values of each measurement. Structured Z-scores were then computed. In all, 853 subjects (age 0 days to 17 years; 45% females; BSA 0.12-2.12m 2 ) were studied. The predicted values and Z-score boundaries are presented. Data are also presented as mean±2 SDs for a given BSA. We report paediatric echocardiographic nomograms for multiple proximal abdominal aorta parameters including pulsed-wave Doppler systolic velocities, deceleration time, wave duration, and two-dimensional vessel diameter variations. Significant variations in these functional indexes with age were found that should be taken into account in clinical practice. At lower ages, steeper and shorter pulsed-wave Doppler peak velocity and limited pulsatility should be expected as physiologic findings. Copyright © 2017 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.

  14. Small-scale open ocean currents have large effects on wind wave heights

    NASA Astrophysics Data System (ADS)

    Ardhuin, Fabrice; Gille, Sarah T.; Menemenlis, Dimitris; Rocha, Cesar B.; Rascle, Nicolas; Chapron, Bertrand; Gula, Jonathan; Molemaker, Jeroen

    2017-06-01

    Tidal currents and large-scale oceanic currents are known to modify ocean wave properties, causing extreme sea states that are a hazard to navigation. Recent advances in the understanding and modeling capability of open ocean currents have revealed the ubiquitous presence of eddies, fronts, and filaments at scales 10-100 km. Based on realistic numerical models, we show that these structures can be the main source of variability in significant wave heights at scales less than 200 km, including important variations down to 10 km. Model results are consistent with wave height variations along satellite altimeter tracks, resolved at scales larger than 50 km. The spectrum of significant wave heights is found to be of the order of 70>>2/>(g2>>2>) times the current spectrum, where >> is the spatially averaged significant wave height, >> is the energy-averaged period, and g is the gravity acceleration. This variability induced by currents has been largely overlooked in spite of its relevance for extreme wave heights and remote sensing.Plain Language SummaryWe show that the <span class="hlt">variations</span> in currents at scales 10 to 100 km are the main source of <span class="hlt">variations</span> in <span class="hlt">wave</span> heights at the same scales. Our work uses a combination of realistic numerical models for currents and <span class="hlt">waves</span> and data from the Jason-3 and SARAL/AltiKa satellites. This finding will be of interest for the investigation of extreme <span class="hlt">wave</span> heights, remote sensing, and air-sea interactions. As an immediate application, the present results will help constrain the error budget of the up-coming satellite missions, in particular the Surface Water and Ocean Topography (SWOT) mission, and decide how the data will have to be processed to arrive at <span class="hlt">accurate</span> sea level and <span class="hlt">wave</span> measurements. It will also help in the analysis of <span class="hlt">wave</span> measurements by the CFOSAT satellite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JGRC..116.6024S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JGRC..116.6024S"><span>Sun glitter imaging of submarine sand <span class="hlt">waves</span> on the Taiwan Banks: Determination of the relaxation rate of short <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shao, Hao; Li, Yan; Li, Li</p> <p>2011-06-01</p> <p>Above sand <span class="hlt">waves</span> on the seafloor, surface short <span class="hlt">waves</span>, which are responsible for the radiance distribution in remote sensing imagery, are modulated gradually by the submarine topography. The relaxation rate μr characterizes the rate at which the short <span class="hlt">waves</span> reach their saturation range after being disturbed. It is a key parameter in the weak hydrodynamic interaction theory and is also a most important parameter in the imaging mechanism used for mapping submarine bottom topography. In this study, a robust expression containing intensity and phase (advection effect) modulations of the perturbed action spectrum of short <span class="hlt">waves</span> was deduced, by using the first-order weak hydrodynamic interaction theory. On the basis of the phase modulation, a method was developed to determine the relaxation rate in the Sun glitter imaging mechanism. The relaxation rates were estimated using in situ data measured on a cruise over the sand <span class="hlt">waves</span> of the Taiwan Banks, a sea area between the East China Sea and the South China Sea, on 28-29 August 2006. Results showed that, under a wind speed of 5.0 m s-1, the relaxation rate of short <span class="hlt">waves</span> was about 0.055 s-1 in response to current <span class="hlt">variations</span> and about 0.025 s-1 equivalently in response to sea bottom topographic <span class="hlt">variations</span>. The former value could be applied to interpret the amplitude of submarine topography by using satellite imagery, while the latter one (equivalent relaxation rate μ'r) could help to more <span class="hlt">accurately</span> calibrate the spatial position of the retrieved sea bottom topography.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22423835','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22423835"><span><span class="hlt">Accurate</span> quantum <span class="hlt">wave</span> packet calculations for the F + HCl → Cl + HF reaction on the ground 1(2)A' potential energy surface.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bulut, Niyazi; Kłos, Jacek; Alexander, Millard H</p> <p>2012-03-14</p> <p>We present converged exact quantum <span class="hlt">wave</span> packet calculations of reaction probabilities, integral cross sections, and thermal rate coefficients for the title reaction. Calculations have been carried out on the ground 1(2)A' global adiabatic potential energy surface of Deskevich et al. [J. Chem. Phys. 124, 224303 (2006)]. Converged <span class="hlt">wave</span> packet reaction probabilities at selected values of the total angular momentum up to a partial <span class="hlt">wave</span> of J = 140 with the HCl reagent initially selected in the v = 0, j = 0-16 rovibrational states have been obtained for the collision energy range from threshold up to 0.8 eV. The present calculations confirm an important enhancement of reactivity with rotational excitation of the HCl molecule. First, <span class="hlt">accurate</span> integral cross sections and rate constants have been calculated and compared with the available experimental data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.S51A2762F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.S51A2762F"><span>The amplitude effects of sedimentary basins on through-passing surface <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Feng, L.; Ritzwoller, M. H.; Pasyanos, M.</p> <p>2016-12-01</p> <p>Understanding the effect of sedimentary basins on through-passing surface <span class="hlt">waves</span> is essential in many aspects of seismology, including the estimation of the magnitude of natural and anthropogenic events, the study of the attenuation properties of Earth's interior, and the analysis of ground motion as part of seismic hazard assessment. In particular, knowledge of the physical causes of amplitude <span class="hlt">variations</span> is important in the application of the Ms:mb discriminant of nuclear monitoring. Our work addresses two principal questions, both in the period range between 10 s and 20 s. The first question is: In what respects can surface <span class="hlt">wave</span> propagation through 3D structures be simulated as 2D membrane <span class="hlt">waves</span>? This question is motivated by our belief that surface <span class="hlt">wave</span> amplitude effects down-stream from sedimentary basins result predominantly from elastic focusing and defocusing, which we understand as analogous to the effect of a lens. To the extent that this understanding is correct, 2D membrane <span class="hlt">waves</span> will approximately capture the amplitude effects of focusing and defocusing. We address this question by applying the 3D simulation code SW4 (a node-based finite-difference code for 3D seismic <span class="hlt">wave</span> simulation) and the 2D code SPECFEM2D (a spectral element code for 2D seismic <span class="hlt">wave</span> simulation). Our results show that for surface <span class="hlt">waves</span> propagating downstream from 3D sedimentary basins, amplitude effects are mostly caused by elastic focusing and defocusing which is modeled <span class="hlt">accurately</span> as a 2D effect. However, if the epicentral distance is small, higher modes may contaminate the fundamental mode, which may result in large errors in the 2D membrane <span class="hlt">wave</span> approximation. The second question is: Are observations of amplitude <span class="hlt">variations</span> across East Asia following North Korean nuclear tests consistent with simulations of amplitude <span class="hlt">variations</span> caused by elastic focusing/defocusing through a crustal reference model of China (Shen et al., A seismic reference model for the crust and uppermost</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JMSA...16..305Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JMSA...16..305Z"><span>Study on unsteady hydrodynamic performance of propeller in <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhao, Qingxin; Guo, Chunyu; Su, Yumin; Liu, Tian; Meng, Xiangyin</p> <p>2017-09-01</p> <p>The speed of a ship sailing in <span class="hlt">waves</span> always slows down due to the decrease in efficiency of the propeller. So it is necessary and essential to analyze the unsteady hydrodynamic performance of propeller in <span class="hlt">waves</span>. This paper is based on the numerical simulation and experimental research of hydrodynamics performance when the propeller is under <span class="hlt">wave</span> conditions. Open-water propeller performance in calm water is calculated by commercial codes and the results are compared to experimental values to evaluate the accuracy of the numerical simulation method. The first-order Volume of Fluid (VOF) <span class="hlt">wave</span> method in STAR CCM+ is utilized to simulate the three-dimensional numerical <span class="hlt">wave</span>. According to the above prerequisite, the numerical calculation of hydrodynamic performance of the propeller under <span class="hlt">wave</span> conditions is conducted, and the results reveal that both thrust and torque of the propeller under <span class="hlt">wave</span> conditions reveal intense unsteady behavior. With the periodic <span class="hlt">variation</span> of <span class="hlt">waves</span>, ventilation, and even an effluent phenomenon appears on the propeller. Calculation results indicate, when ventilation or effluent appears, the numerical calculation model can capture the dynamic characteristics of the propeller <span class="hlt">accurately</span>, thus providing a significant theory foundation for further studying the hydrodynamic performance of a propeller in <span class="hlt">waves</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.H13K1564Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.H13K1564Y"><span>Improving the <span class="hlt">accurate</span> assessment of a layered shear-<span class="hlt">wave</span> velocity model using joint inversion of the effective Rayleigh <span class="hlt">wave</span> and Love <span class="hlt">wave</span> dispersion curves</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yin, X.; Xia, J.; Xu, H.</p> <p>2016-12-01</p> <p>Rayleigh and Love <span class="hlt">waves</span> are two types of surface <span class="hlt">waves</span> that travel along a free surface.Based on the assumption of horizontal layered homogenous media, Rayleigh-<span class="hlt">wave</span> phase velocity can be defined as a function of frequency and four groups of earth parameters: P-<span class="hlt">wave</span> velocity, SV-<span class="hlt">wave</span> velocity, density and thickness of each layer. Unlike Rayleigh <span class="hlt">waves</span>, Love-<span class="hlt">wave</span> phase velocities of a layered homogenous earth model could be calculated using frequency and three groups of earth properties: SH-<span class="hlt">wave</span> velocity, density, and thickness of each layer. Because the dispersion of Love <span class="hlt">waves</span> is independent of P-<span class="hlt">wave</span> velocities, Love-<span class="hlt">wave</span> dispersion curves are much simpler than Rayleigh <span class="hlt">wave</span>. The research of joint inversion methods of Rayleigh and Love dispersion curves is necessary. (1) This dissertation adopts the combinations of theoretical analysis and practical applications. In both lateral homogenous media and radial anisotropic media, joint inversion approaches of Rayleigh and Love <span class="hlt">waves</span> are proposed to improve the accuracy of S-<span class="hlt">wave</span> velocities.A 10% random white noise and a 20% random white noise are added to the synthetic dispersion curves to check out anti-noise ability of the proposed joint inversion method.Considering the influences of the anomalous layer, Rayleigh and Love <span class="hlt">waves</span> are insensitive to those layers beneath the high-velocity layer or low-velocity layer and the high-velocity layer itself. Low sensitivities will give rise to high degree of uncertainties of the inverted S-<span class="hlt">wave</span> velocities of these layers. Considering that sensitivity peaks of Rayleigh and Love <span class="hlt">waves</span> separate at different frequency ranges, the theoretical analyses have demonstrated that joint inversion of these two types of <span class="hlt">waves</span> would probably ameliorate the inverted model.The lack of surface-<span class="hlt">wave</span> (Rayleigh or Love <span class="hlt">waves</span>) dispersion data may lead to inaccuracy S-<span class="hlt">wave</span> velocities through the single inversion of Rayleigh or Love <span class="hlt">waves</span>, so this dissertation presents the joint inversion method of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910013199','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910013199"><span>Computation of viscous blast <span class="hlt">wave</span> flowfields</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Atwood, Christopher A.</p> <p>1991-01-01</p> <p>A method to determine unsteady solutions of the Navier-Stokes equations was developed and applied. The structural finite-volume, approximately factored implicit scheme uses Newton subiterations to obtain the spatially and temporally second-order <span class="hlt">accurate</span> time history of the interaction of blast-<span class="hlt">waves</span> with stationary targets. The inviscid flux is evaluated using MacCormack's modified Steger-Warming flux or Roe flux difference splittings with total <span class="hlt">variation</span> diminishing limiters, while the viscous flux is computed using central differences. The use of implicit boundary conditions in conjunction with a telescoping in time and space method permitted solutions to this strongly unsteady class of problems. Comparisons of numerical, analytical, and experimental results were made in two and three dimensions. These comparisons revealed <span class="hlt">accurate</span> <span class="hlt">wave</span> speed resolution with nonoscillatory discontinuity capturing. The purpose of this effort was to address the three-dimensional, viscous blast-<span class="hlt">wave</span> problem. Test cases were undertaken to reveal these methods' weaknesses in three regimes: (1) viscous-dominated flow; (2) complex unsteady flow; and (3) three-dimensional flow. Comparisons of these computations to analytic and experimental results provided initial validation of the resultant code. Addition details on the numerical method and on the validation can be found in the appendix. Presently, the code is capable of single zone computations with selection of any permutation of solid wall or flow-through boundaries.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_5 --> <div id="page_6" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="101"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22759434','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22759434"><span><span class="hlt">Accurate</span> respiration measurement using DC-coupled continuous-<span class="hlt">wave</span> radar sensor for motion-adaptive cancer radiotherapy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gu, Changzhan; Li, Ruijiang; Zhang, Hualiang; Fung, Albert Y C; Torres, Carlos; Jiang, Steve B; Li, Changzhi</p> <p>2012-11-01</p> <p><span class="hlt">Accurate</span> respiration measurement is crucial in motion-adaptive cancer radiotherapy. Conventional methods for respiration measurement are undesirable because they are either invasive to the patient or do not have sufficient accuracy. In addition, measurement of external respiration signal based on conventional approaches requires close patient contact to the physical device which often causes patient discomfort and undesirable motion during radiation dose delivery. In this paper, a dc-coupled continuous-<span class="hlt">wave</span> radar sensor was presented to provide a noncontact and noninvasive approach for respiration measurement. The radar sensor was designed with dc-coupled adaptive tuning architectures that include RF coarse-tuning and baseband fine-tuning, which allows the radar sensor to precisely measure movement with stationary moment and always work with the maximum dynamic range. The accuracy of respiration measurement with the proposed radar sensor was experimentally evaluated using a physical phantom, human subject, and moving plate in a radiotherapy environment. It was shown that respiration measurement with radar sensor while the radiation beam is on is feasible and the measurement has a submillimeter accuracy when compared with a commercial respiration monitoring system which requires patient contact. The proposed radar sensor provides <span class="hlt">accurate</span>, noninvasive, and noncontact respiration measurement and therefore has a great potential in motion-adaptive radiotherapy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1438754','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1438754"><span>High Order <span class="hlt">Accurate</span> Finite Difference Modeling of Seismo-Acoustic <span class="hlt">Wave</span> Propagation in a Moving Atmosphere and a Heterogeneous Earth Model Coupled Across a Realistic Topography</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Petersson, N. Anders; Sjogreen, Bjorn</p> <p></p> <p>Here, we develop a numerical method for simultaneously simulating acoustic <span class="hlt">waves</span> in a realistic moving atmosphere and seismic <span class="hlt">waves</span> in a heterogeneous earth model, where the motions are coupled across a realistic topography. We model acoustic <span class="hlt">wave</span> propagation by solving the linearized Euler equations of compressible fluid mechanics. The seismic <span class="hlt">waves</span> are modeled by the elastic <span class="hlt">wave</span> equation in a heterogeneous anisotropic material. The motion is coupled by imposing continuity of normal velocity and normal stresses across the topographic interface. Realistic topography is resolved on a curvilinear grid that follows the interface. The governing equations are discretized using high ordermore » <span class="hlt">accurate</span> finite difference methods that satisfy the principle of summation by parts. We apply the energy method to derive the discrete interface conditions and to show that the coupled discretization is stable. The implementation is verified by numerical experiments, and we demonstrate a simulation of coupled <span class="hlt">wave</span> propagation in a windy atmosphere and a realistic earth model with non-planar topography.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1438754-high-order-accurate-finite-difference-modeling-seismo-acoustic-wave-propagation-moving-atmosphere-heterogeneous-earth-model-coupled-across-realistic-topography','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1438754-high-order-accurate-finite-difference-modeling-seismo-acoustic-wave-propagation-moving-atmosphere-heterogeneous-earth-model-coupled-across-realistic-topography"><span>High Order <span class="hlt">Accurate</span> Finite Difference Modeling of Seismo-Acoustic <span class="hlt">Wave</span> Propagation in a Moving Atmosphere and a Heterogeneous Earth Model Coupled Across a Realistic Topography</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Petersson, N. Anders; Sjogreen, Bjorn</p> <p>2017-04-18</p> <p>Here, we develop a numerical method for simultaneously simulating acoustic <span class="hlt">waves</span> in a realistic moving atmosphere and seismic <span class="hlt">waves</span> in a heterogeneous earth model, where the motions are coupled across a realistic topography. We model acoustic <span class="hlt">wave</span> propagation by solving the linearized Euler equations of compressible fluid mechanics. The seismic <span class="hlt">waves</span> are modeled by the elastic <span class="hlt">wave</span> equation in a heterogeneous anisotropic material. The motion is coupled by imposing continuity of normal velocity and normal stresses across the topographic interface. Realistic topography is resolved on a curvilinear grid that follows the interface. The governing equations are discretized using high ordermore » <span class="hlt">accurate</span> finite difference methods that satisfy the principle of summation by parts. We apply the energy method to derive the discrete interface conditions and to show that the coupled discretization is stable. The implementation is verified by numerical experiments, and we demonstrate a simulation of coupled <span class="hlt">wave</span> propagation in a windy atmosphere and a realistic earth model with non-planar topography.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeoRL..41..799L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeoRL..41..799L"><span>Full-<span class="hlt">wave</span> effects on shear <span class="hlt">wave</span> splitting</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lin, Yu-Pin; Zhao, Li; Hung, Shu-Huei</p> <p>2014-02-01</p> <p>Seismic anisotropy in the mantle plays an important role in our understanding of the Earth's internal dynamics, and shear <span class="hlt">wave</span> splitting has always been a key observable in the investigation of seismic anisotropy. To date the interpretation of shear <span class="hlt">wave</span> splitting in terms of anisotropy has been largely based on ray-theoretical modeling of a single vertically incident plane SKS or SKKS <span class="hlt">wave</span>. In this study, we use sensitivity kernels of shear <span class="hlt">wave</span> splitting to anisotropic parameters calculated by the normal-mode theory to demonstrate that the interference of SKS with other phases of similar arrival times, near-field effect, and multiple reflections in the crust lead to significant <span class="hlt">variations</span> of SKS splitting with epicentral distance. The full-<span class="hlt">wave</span> kernels not only widen the possibilities in the source-receiver geometry in making shear <span class="hlt">wave</span> splitting measurements but also provide the capability for tomographic inversion to resolve vertical and lateral <span class="hlt">variations</span> in the anisotropic structures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26670847','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26670847"><span>Shear <span class="hlt">wave</span> arrival time estimates correlate with local speckle pattern.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mcaleavey, Stephen A; Osapoetra, Laurentius O; Langdon, Jonathan</p> <p>2015-12-01</p> <p>We present simulation and phantom studies demonstrating a strong correlation between errors in shear <span class="hlt">wave</span> arrival time estimates and the lateral position of the local speckle pattern in targets with fully developed speckle. We hypothesize that the observed arrival time <span class="hlt">variations</span> are largely due to the underlying speckle pattern, and call the effect speckle bias. Arrival time estimation is a key step in quantitative shear <span class="hlt">wave</span> elastography, performed by tracking tissue motion via cross-correlation of RF ultrasound echoes or similar methods. <span class="hlt">Variations</span> in scatterer strength and interference of echoes from scatterers within the tracking beam result in an echo that does not necessarily describe the average motion within the beam, but one favoring areas of constructive interference and strong scattering. A swept-receive image, formed by fixing the transmit beam and sweeping the receive aperture over the region of interest, is used to estimate the local speckle pattern. Metrics for the lateral position of the speckle are found to correlate strongly (r > 0.7) with the estimated shear <span class="hlt">wave</span> arrival times both in simulations and in phantoms. Lateral weighting of the swept-receive pattern improved the correlation between arrival time estimates and speckle position. The simulations indicate that high RF echo correlation does not equate to an <span class="hlt">accurate</span> shear <span class="hlt">wave</span> arrival time estimate-a high correlation coefficient indicates that motion is being tracked with high precision, but the location tracked is uncertain within the tracking beam width. The presence of a strong on-axis speckle is seen to imply high RF correlation and low bias. The converse does not appear to be true-highly correlated RF echoes can still produce biased arrival time estimates. The shear <span class="hlt">wave</span> arrival time bias is relatively stable with <span class="hlt">variations</span> in shear <span class="hlt">wave</span> amplitude and sign (-20 μm to 20 μm simulated) compared with the <span class="hlt">variation</span> with different speckle realizations obtained along a given tracking</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/21179972-how-accurately-does-free-complement-wave-function-helium-atom-satisfy-schroedinger-equation','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/21179972-how-accurately-does-free-complement-wave-function-helium-atom-satisfy-schroedinger-equation"><span>How <span class="hlt">Accurately</span> Does the Free Complement <span class="hlt">Wave</span> Function of a Helium Atom Satisfy the Schroedinger Equation?</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Nakashima, Hiroyuki; Nakatsuji, Hiroshi</p> <p>2008-12-12</p> <p>The local energy defined by H{psi}/{psi} must be equal to the exact energy E at any coordinate of an atom or molecule, as long as the {psi} under consideration is exact. The discrepancy from E of this quantity is a stringent test of the accuracy of the calculated <span class="hlt">wave</span> function. The H-square error for a normalized {psi}, defined by {sigma}{sup 2}{identical_to}<{psi}|(H-E){sup 2}|{psi}>, is also a severe test of the accuracy. Using these quantities, we have examined the accuracy of our <span class="hlt">wave</span> function of a helium atom calculated using the free complement method that was developed to solve the Schroedinger equation.more » Together with the <span class="hlt">variational</span> upper bound, the lower bound of the exact energy calculated using a modified Temple's formula ensured the definitely correct value of the helium fixed-nucleus ground state energy to be -2.903 724 377 034 119 598 311 159 245 194 4 a.u., which is correct to 32 digits.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JASTP.171..260A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JASTP.171..260A"><span>On the importance of an atmospheric reference model: A case study on gravity <span class="hlt">wave</span>-airglow interactions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Amaro-Rivera, Yolián; Huang, Tai-Yin; Urbina, Julio</p> <p>2018-06-01</p> <p>The atmospheric reference model utilized in an airglow numerical study is important since airglow emissions depend on the number density of the light-emitting species. In this study, we employ 2-dimensional, nonlinear, time-dependent numerical models, Multiple Airglow Chemistry Dynamics (MACD) and OH Chemistry Dynamics (OHCD), that use the MSISE-90, NRLMSISE-00, and Garcia and Solomon (GS) model data as atmospheric reference models, to investigate gravity <span class="hlt">wave</span>-induced airglow <span class="hlt">variations</span> for the OH(8,3) airglow, O2(0,1) atmospheric band, and O(1S) greenline emissions in the Mesosphere and Lower Thermosphere (MLT) region. Our results show that the OHCD-00 produces the largest <span class="hlt">wave</span>-induced OH(8,3) airglow intensity <span class="hlt">variation</span> (∼34%), followed by the OHCD-90 (∼30%), then by the OHCD (∼22%). For O(1S) greenline, the MACD produces the largest <span class="hlt">wave</span>-induced <span class="hlt">variation</span> (∼33%), followed by the MACD-90 (∼28%), then by MACD-00 (∼26%). As for O2(0,1) atmospheric band, the MACD produces the largest <span class="hlt">wave</span>-induced <span class="hlt">variation</span> (∼31%), followed by the MACD-90 and MACD-00 (∼29%). Our study illustrates the importance and the need for a good atmospheric reference model that can <span class="hlt">accurately</span> represent the atmosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170003144&hterms=particle&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dparticle','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170003144&hterms=particle&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dparticle"><span><span class="hlt">Accurately</span> Characterizing the Importance of <span class="hlt">Wave</span>-Particle Interactions in Radiation Belt Dynamics: The Pitfalls of Statistical <span class="hlt">Wave</span> Representations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Murphy, Kyle R.; Mann, Ian R.; Rae, I. Jonathan; Sibeck, David G.; Watt, Clare E. J.</p> <p>2016-01-01</p> <p><span class="hlt">Wave</span>-particle interactions play a crucial role in energetic particle dynamics in the Earths radiation belts. However, the relative importance of different <span class="hlt">wave</span> modes in these dynamics is poorly understood. Typically, this is assessed during geomagnetic storms using statistically averaged empirical <span class="hlt">wave</span> models as a function of geomagnetic activity in advanced radiation belt simulations. However, statistical averages poorly characterize extreme events such as geomagnetic storms in that storm-time ultralow frequency <span class="hlt">wave</span> power is typically larger than that derived over a solar cycle and Kp is a poor proxy for storm-time <span class="hlt">wave</span> power.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=golf&pg=2&id=EJ990084','ERIC'); return false;" href="https://eric.ed.gov/?q=golf&pg=2&id=EJ990084"><span>Feedback about More <span class="hlt">Accurate</span> versus Less <span class="hlt">Accurate</span> Trials: Differential Effects on Self-Confidence and Activation</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Badami, Rokhsareh; VaezMousavi, Mohammad; Wulf, Gabriele; Namazizadeh, Mahdi</p> <p>2012-01-01</p> <p>One purpose of the present study was to examine whether self-confidence or anxiety would be differentially affected by feedback from more <span class="hlt">accurate</span> rather than less <span class="hlt">accurate</span> trials. The second purpose was to determine whether arousal <span class="hlt">variations</span> (activation) would predict performance. On Day 1, participants performed a golf putting task under one of…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSM21A2577K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM21A2577K"><span><span class="hlt">Accurate</span> calibration of waveform data measured by the Plasma <span class="hlt">Wave</span> Experiment on board the ARASE satellite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kitahara, M.; Katoh, Y.; Hikishima, M.; Kasahara, Y.; Matsuda, S.; Kojima, H.; Ozaki, M.; Yagitani, S.</p> <p>2017-12-01</p> <p>The Plasma <span class="hlt">Wave</span> Experiment (PWE) is installed on board the ARASE satellite to measure the electric field in the frequency range from DC to 10 MHz, and the magnetic field in the frequency range from a few Hz to 100 kHz using two dipole wire-probe antennas (WPT) and three magnetic search coils (MSC), respectively. In particular, the Waveform Capture (WFC), one of the receivers of the PWE, can detect electromagnetic field waveform in the frequency range from a few Hz to 20 kHz. The Software-type <span class="hlt">Wave</span> Particle Interaction Analyzer (S-WPIA) is installed on the ARASE satellite to measure the energy exchange between plasma <span class="hlt">waves</span> and particles. Since S-WPIA uses the waveform data measured by WFC to calculate the relative phase angle between the <span class="hlt">wave</span> magnetic field and velocity of energetic electrons, the high-accuracy is required to calibration of both amplitude and phase of the waveform data. Generally, the calibration procedure of the signal passed through a receiver consists of three steps; the transformation into spectra, the calibration by the transfer function of a receiver, and the inverse transformation of the calibrated spectra into the time domain. Practically, in order to reduce the side robe effect, a raw data is filtered by a window function in the time domain before applying Fourier transform. However, for the case that a first order differential coefficient of the phase transfer function of the system is not negligible, the phase of the window function convoluted into the calibrated spectra is shifted differently at each frequency, resulting in a discontinuity in the time domain of the calibrated waveform data. To eliminate the effect of the phase shift of a window function, we suggest several methods to calibrate a waveform data <span class="hlt">accurately</span> and carry out simulations assuming simple sinusoidal <span class="hlt">waves</span> as an input signal and using transfer functions of WPT, MSC, and WFC obtained in pre-flight tests. In consequence, we conclude that the following two methods can</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017OptEn..56k6103R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017OptEn..56k6103R"><span>Exact solitary <span class="hlt">wave</span> solution for higher order nonlinear Schrodinger equation using He's <span class="hlt">variational</span> iteration method</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rani, Monika; Bhatti, Harbax S.; Singh, Vikramjeet</p> <p>2017-11-01</p> <p>In optical communication, the behavior of the ultrashort pulses of optical solitons can be described through nonlinear Schrodinger equation. This partial differential equation is widely used to contemplate a number of physically important phenomena, including optical shock <span class="hlt">waves</span>, laser and plasma physics, quantum mechanics, elastic media, etc. The exact analytical solution of (1+n)-dimensional higher order nonlinear Schrodinger equation by He's <span class="hlt">variational</span> iteration method has been presented. Our proposed solutions are very helpful in studying the solitary <span class="hlt">wave</span> phenomena and ensure rapid convergent series and avoid round off errors. Different examples with graphical representations have been given to justify the capability of the method.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1250177-photoelectron-wave-function-photoionization-plane-wave-coulomb-wave-does-photoionization-neutral-targets-produce-coulomb-plane-waves','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1250177-photoelectron-wave-function-photoionization-plane-wave-coulomb-wave-does-photoionization-neutral-targets-produce-coulomb-plane-waves"><span>Photoelectron <span class="hlt">wave</span> function in photoionization: Plane <span class="hlt">wave</span> or Coulomb <span class="hlt">wave</span>? [Does photoionization of neutral targets produce Coulomb or plane <span class="hlt">waves</span>?</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Gozem, Samer; Gunina, Anastasia O.; Ichino, Takatoshi; ...</p> <p>2015-10-28</p> <p>The calculation of absolute total cross sections requires <span class="hlt">accurate</span> <span class="hlt">wave</span> functions of the photoelectron and of the initial and final states of the system. The essential information contained in the latter two can be condensed into a Dyson orbital. We employ correlated Dyson orbitals and test approximate treatments of the photoelectron <span class="hlt">wave</span> function, that is, plane and Coulomb <span class="hlt">waves</span>, by comparing computed and experimental photoionization and photodetachment spectra. We find that in anions, a plane <span class="hlt">wave</span> treatment of the photoelectron provides a good description of photodetachment spectra. For photoionization of neutral atoms or molecules with one heavy atom, the photoelectronmore » <span class="hlt">wave</span> function must be treated as a Coulomb <span class="hlt">wave</span> to account for the interaction of the photoelectron with the +1 charge of the ionized core. For larger molecules, the best agreement with experiment is often achieved by using a Coulomb <span class="hlt">wave</span> with a partial (effective) charge smaller than unity. This likely derives from the fact that the effective charge at the centroid of the Dyson orbital, which serves as the origin of the spherical <span class="hlt">wave</span> expansion, is smaller than the total charge of a polyatomic cation. Finally, the results suggest that <span class="hlt">accurate</span> molecular photoionization cross sections can be computed with a modified central potential model that accounts for the nonspherical charge distribution of the core by adjusting the charge in the center of the expansion.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4949423','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4949423"><span>Depth <span class="hlt">variations</span> of P-<span class="hlt">wave</span> azimuthal anisotropy beneath Mainland China</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wei, Wei; Zhao, Dapeng; Xu, Jiandong; Zhou, Bengang; Shi, Yaolin</p> <p>2016-01-01</p> <p>A high-resolution model of P-<span class="hlt">wave</span> anisotropic tomography beneath Mainland China and surrounding regions is determined using a large number of arrival-time data recorded by the China seismic network, the International Seismological Centre (ISC) and temporary seismic arrays deployed on the Tibetan Plateau. Our results provide important new insights into the subducted Indian plate and mantle dynamics in East Asia. Our tomographic images show that the northern limit of the subducting Indian plate has reached the Jinsha River suture in eastern Tibet. A striking <span class="hlt">variation</span> of P-<span class="hlt">wave</span> azimuthal anisotropy is revealed in the Indian lithosphere: the fast velocity direction (FVD) is NE-SW beneath the Indian continent, whereas the FVD is arc parallel beneath the Himalaya and Tibetan Plateau, which may reflect re-orientation of minerals due to lithospheric extension, in response to the India-Eurasia collision. There are multiple anisotropic layers with variable FVDs in some parts of the Tibetan Plateau, which may be the cause of the dominant null splitting measurements in these regions. A circular pattern of FVDs is revealed around the Philippine Sea slab beneath SE China, which reflects asthenospheric strain caused by toroidal mantle flow around the edge of the subducting slab. PMID:27432744</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...629614W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...629614W"><span>Depth <span class="hlt">variations</span> of P-<span class="hlt">wave</span> azimuthal anisotropy beneath Mainland China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wei, Wei; Zhao, Dapeng; Xu, Jiandong; Zhou, Bengang; Shi, Yaolin</p> <p>2016-07-01</p> <p>A high-resolution model of P-<span class="hlt">wave</span> anisotropic tomography beneath Mainland China and surrounding regions is determined using a large number of arrival-time data recorded by the China seismic network, the International Seismological Centre (ISC) and temporary seismic arrays deployed on the Tibetan Plateau. Our results provide important new insights into the subducted Indian plate and mantle dynamics in East Asia. Our tomographic images show that the northern limit of the subducting Indian plate has reached the Jinsha River suture in eastern Tibet. A striking <span class="hlt">variation</span> of P-<span class="hlt">wave</span> azimuthal anisotropy is revealed in the Indian lithosphere: the fast velocity direction (FVD) is NE-SW beneath the Indian continent, whereas the FVD is arc parallel beneath the Himalaya and Tibetan Plateau, which may reflect re-orientation of minerals due to lithospheric extension, in response to the India-Eurasia collision. There are multiple anisotropic layers with variable FVDs in some parts of the Tibetan Plateau, which may be the cause of the dominant null splitting measurements in these regions. A circular pattern of FVDs is revealed around the Philippine Sea slab beneath SE China, which reflects asthenospheric strain caused by toroidal mantle flow around the edge of the subducting slab.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22410444-relativistic-electron-scattering-magnetosonic-waves-effects-discrete-wave-emission-high-wave-amplitudes','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22410444-relativistic-electron-scattering-magnetosonic-waves-effects-discrete-wave-emission-high-wave-amplitudes"><span>Relativistic electron scattering by magnetosonic <span class="hlt">waves</span>: Effects of discrete <span class="hlt">wave</span> emission and high <span class="hlt">wave</span> amplitudes</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Artemyev, A. V., E-mail: ante0226@gmail.com; Mourenas, D.; Krasnoselskikh, V. V.</p> <p>2015-06-15</p> <p>In this paper, we study relativistic electron scattering by fast magnetosonic <span class="hlt">waves</span>. We compare results of test particle simulations and the quasi-linear theory for different spectra of <span class="hlt">waves</span> to investigate how a fine structure of the <span class="hlt">wave</span> emission can influence electron resonant scattering. We show that for a realistically wide distribution of <span class="hlt">wave</span> normal angles θ (i.e., when the dispersion δθ≥0.5{sup °}), relativistic electron scattering is similar for a wide <span class="hlt">wave</span> spectrum and for a spectrum consisting in well-separated ion cyclotron harmonics. Comparisons of test particle simulations with quasi-linear theory show that for δθ>0.5{sup °}, the quasi-linear approximation describes resonantmore » scattering correctly for a large enough plasma frequency. For a very narrow θ distribution (when δθ∼0.05{sup °}), however, the effect of a fine structure in the <span class="hlt">wave</span> spectrum becomes important. In this case, quasi-linear theory clearly fails in describing <span class="hlt">accurately</span> electron scattering by fast magnetosonic <span class="hlt">waves</span>. We also study the effect of high <span class="hlt">wave</span> amplitudes on relativistic electron scattering. For typical conditions in the earth's radiation belts, the quasi-linear approximation cannot <span class="hlt">accurately</span> describe electron scattering for <span class="hlt">waves</span> with averaged amplitudes >300 pT. We discuss various applications of the obtained results for modeling electron dynamics in the radiation belts and in the Earth's magnetotail.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018GeoJI.tmp..204S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018GeoJI.tmp..204S"><span>Modeling the blockage of Lg <span class="hlt">waves</span> from 3-D <span class="hlt">variations</span> in crustal structure</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sanborn, Christopher J.; Cormier, Vernon F.</p> <p>2018-05-01</p> <p>Comprised of S <span class="hlt">waves</span> trapped in Earth's crust, the high frequency (2-10 Hz) Lg <span class="hlt">wave</span> is important to discriminating earthquakes from explosions by comparing its amplitude and waveform to those of Pg and Pn <span class="hlt">waves</span>. Lateral <span class="hlt">variations</span> in crustal structure, including <span class="hlt">variations</span> in crustal thickness, intrinsic attenuation, and scattering, affect the efficiency of Lg propagation and its consistency as a source discriminant at regional (200-1500 km) distances. To investigate the effects of laterally varying Earth structure on the efficiency of propagation of Lg and Pg, we apply a radiative transport algorithm to model complete, high-frequency (2-4 Hz), regional coda envelopes. The algorithm propagates packets of energy with ray theory through large-scale 3-D structure, and includes stochastic effects of multiple-scattering by small-scale heterogeneities within the large-scale structure. Source-radiation patterns are described by moment tensors. Seismograms of explosion and earthquake sources are synthesized in canonical models to predict effects on waveforms of paths crossing regions of crustal thinning (pull-apart basins and ocean/continent transitions) and thickening (collisional mountain belts), For paths crossing crustal thinning regions, Lg is amplified at receivers within the thinned region but strongly disrupted and attenuated at receivers beyond the thinned region. For paths crossing regions of crustal thickening, Lg amplitude is attenuated at receivers within the thickened region, but experiences little or no reduction in amplitude at receivers beyond the thickened region. The length of the Lg propagation within a thickened region and the complexity of over- and under-thrust crustal layers, can produce localized zones of Lg amplification or attenuation. Regions of intense scattering within laterally homogeneous models of the crust increase Lg attenuation but do not disrupt its coda shape.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29431681','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29431681"><span>Hartree-Fock implementation using a Laguerre-based <span class="hlt">wave</span> function for the ground state and correlation energies of two-electron atoms.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>King, Andrew W; Baskerville, Adam L; Cox, Hazel</p> <p>2018-03-13</p> <p>An implementation of the Hartree-Fock (HF) method using a Laguerre-based <span class="hlt">wave</span> function is described and used to <span class="hlt">accurately</span> study the ground state of two-electron atoms in the fixed nucleus approximation, and by comparison with fully correlated (FC) energies, used to determine <span class="hlt">accurate</span> electron correlation energies. A <span class="hlt">variational</span> parameter A is included in the <span class="hlt">wave</span> function and is shown to rapidly increase the convergence of the energy. The one-electron integrals are solved by series solution and an analytical form is found for the two-electron integrals. This methodology is used to produce <span class="hlt">accurate</span> <span class="hlt">wave</span> functions, energies and expectation values for the helium isoelectronic sequence, including at low nuclear charge just prior to electron detachment. Additionally, the critical nuclear charge for binding two electrons within the HF approach is calculated and determined to be Z HF C =1.031 177 528.This article is part of the theme issue 'Modern theoretical chemistry'. © 2018 The Author(s).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AdSpR..58..326G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AdSpR..58..326G"><span>Modeling the <span class="hlt">variations</span> of reflection coefficient of Earth's lower ionosphere using very low frequency radio <span class="hlt">wave</span> data by artificial neural network</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ghanbari, Keyvan; Khakian Ghomi, Mehdi; Mohammadi, Mohammad; Marbouti, Marjan; Tan, Le Minh</p> <p>2016-08-01</p> <p>The ionized atmosphere lying from 50 to 600 km above surface, known as ionosphere, contains high amount of electrons and ions. Very Low Frequency (VLF) radio <span class="hlt">waves</span> with frequencies between 3 and 30 kHz are reflected from the lower ionosphere specifically D-region. A lot of applications in long range communications and navigation systems have been inspired by this characteristic of ionosphere. There are several factors which affect the ionization rate in this region, such as: time of day (presence of sun in the sky), solar zenith angle (seasons) and solar activities. Due to nonlinear response of ionospheric reflection coefficient to these factors, finding an <span class="hlt">accurate</span> relation between these parameters and reflection coefficient is an arduous task. In order to model these kinds of nonlinear functionalities, some numerical methods are employed. One of these methods is artificial neural network (ANN). In this paper, the VLF radio <span class="hlt">wave</span> data of 4 sudden ionospheric disturbance (SID) stations are given to a multi-layer perceptron ANN in order to simulate the <span class="hlt">variations</span> of reflection coefficient of D region ionosphere. After training, validation and testing the ANN, outputs of ANN and observed values are plotted together for 2 random cases of each station. By evaluating the results using 2 parameters of pearson correlation coefficient and root mean square error, a satisfying agreement was found between ANN outputs and real observed data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRC..122.2205R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRC..122.2205R"><span>Current-induced dissipation in spectral <span class="hlt">wave</span> models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rapizo, H.; Babanin, A. V.; Provis, D.; Rogers, W. E.</p> <p>2017-03-01</p> <p>Despite many recent developments of the parameterization for <span class="hlt">wave</span> dissipation in spectral models, it is evident that when <span class="hlt">waves</span> propagate onto strong adverse currents the rate of energy dissipation is not properly estimated. The issue of current-induced dissipation is studied through a comprehensive data set in the tidal inlet of Port Phillip Heads, Australia. The <span class="hlt">wave</span> parameters analyzed are significantly modulated by the tidal currents. <span class="hlt">Wave</span> height in conditions of opposing currents (ebb tide) can reach twice the offshore value, whereas during coflowing currents (flood), it can be reduced to half. The wind-<span class="hlt">wave</span> model SWAN is able to reproduce the tide-induced modulation of <span class="hlt">waves</span> and the results show that the <span class="hlt">variation</span> of currents is the dominant factor in modifying the <span class="hlt">wave</span> field. In stationary simulations, the model provides an <span class="hlt">accurate</span> representation of <span class="hlt">wave</span> height for slack and flood tides. During ebb tides, <span class="hlt">wave</span> energy is highly overestimated over the opposing current jet. None of the four parameterizations for <span class="hlt">wave</span> dissipation tested performs satisfactorily. A modification to enhance dissipation as a function of the local currents is proposed. It consists of the addition of a factor that represents current-induced <span class="hlt">wave</span> steepening and it is scaled by the ratio of spectral energy to the threshold breaking level. The new term asymptotes to the original form as the current in the <span class="hlt">wave</span> direction tends to zero. The proposed modification considerably improves <span class="hlt">wave</span> height and mean period in conditions of adverse currents, whereas the good model performance in coflowing currents is unaltered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JPhCS1011a2050D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JPhCS1011a2050D"><span>10 GHz Standing-<span class="hlt">Wave</span> Coplanar Stripline on LiNbO3 Crystal for Radio to Optical-<span class="hlt">Wave</span> Conversion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Darwis, F.; Wijayanto, Y. N.; Setiawan, A.; Mahmudin, D.; Rahman, A. N.; Daud, P.</p> <p>2018-04-01</p> <p>Recently, X-band radar systems are used widely for surveillance and navigation applications. Especially in archipelago or maritime country, the surveillance/navigation radar systems are required to monitoring critical areas and managing marine traffic. <span class="hlt">Accurate</span> detection and fast analysis should be improved furthermore to provide security and safety condition. Therefore, several radar systems should be installed in many places to coverage the critical areas within radar networks. The radar network can be connected using optical fibers since it has extremely low propagation loss with optical-<span class="hlt">wave</span> to carry-out the radar-<span class="hlt">wave</span>. One important component in the scenario is a radio to optical-<span class="hlt">wave</span> conversion component. In this paper, we report a 10 GHz radio to optical-<span class="hlt">wave</span> conversion component using standing-<span class="hlt">wave</span> coplanar stripline (CPS) on LiNbO3 optical crystal as the substrate. The standing-<span class="hlt">wave</span> CPS electrodes with narrow slot are arranged in an array structure. An optical waveguide is located close to the narrow slot. The CPS electrodes were analysed using electromagnetic analysis software for 10 GHz operational frequency. Responses for slot width and electrode length <span class="hlt">variation</span> are reported. As results, return loss of -14.580 dB and -19.517 dB are obtained for single and array CPS electrodes respectively. Optimization of the designed radio to optical-<span class="hlt">wave</span> conversion devices was also done.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_6 --> <div id="page_7" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="121"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=function+AND+wave&pg=2&id=EJ691836','ERIC'); return false;" href="https://eric.ed.gov/?q=function+AND+wave&pg=2&id=EJ691836"><span>Demonstration of Systematic Improvements in Application of the <span class="hlt">Variational</span> Method to Strongly Bound Potentials</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Ninemire, B.; Mei, W. N.</p> <p>2004-01-01</p> <p>In applying the <span class="hlt">variational</span> method, six different sets of trial <span class="hlt">wave</span> functions are used to calculate the ground state and first excited state energies of the strongly bound potentials, i.e. V(x)=x[2m], where m = 4, 5 and 6. It is shown that <span class="hlt">accurate</span> results can be obtained from thorough analysis of the asymptotic behaviour of the solutions.…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22686372','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22686372"><span>Discovery of a general method of solving the Schrödinger and dirac equations that opens a way to <span class="hlt">accurately</span> predictive quantum chemistry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nakatsuji, Hiroshi</p> <p>2012-09-18</p> <p>Just as Newtonian law governs classical physics, the Schrödinger equation (SE) and the relativistic Dirac equation (DE) rule the world of chemistry. So, if we can solve these equations <span class="hlt">accurately</span>, we can use computation to predict chemistry precisely. However, for approximately 80 years after the discovery of these equations, chemists believed that they could not solve SE and DE for atoms and molecules that included many electrons. This Account reviews ideas developed over the past decade to further the goal of predictive quantum chemistry. Between 2000 and 2005, I discovered a general method of solving the SE and DE <span class="hlt">accurately</span>. As a first inspiration, I formulated the structure of the exact <span class="hlt">wave</span> function of the SE in a compact mathematical form. The explicit inclusion of the exact <span class="hlt">wave</span> function's structure within the <span class="hlt">variational</span> space allows for the calculation of the exact <span class="hlt">wave</span> function as a solution of the <span class="hlt">variational</span> method. Although this process sounds almost impossible, it is indeed possible, and I have published several formulations and applied them to solve the full configuration interaction (CI) with a very small number of variables. However, when I examined analytical solutions for atoms and molecules, the Hamiltonian integrals in their secular equations diverged. This singularity problem occurred in all atoms and molecules because it originates from the singularity of the Coulomb potential in their Hamiltonians. To overcome this problem, I first introduced the inverse SE and then the scaled SE. The latter simpler idea led to immediate and surprisingly <span class="hlt">accurate</span> solution for the SEs of the hydrogen atom, helium atom, and hydrogen molecule. The free complement (FC) method, also called the free iterative CI (free ICI) method, was efficient for solving the SEs. In the FC method, the basis functions that span the exact <span class="hlt">wave</span> function are produced by the Hamiltonian of the system and the zeroth-order <span class="hlt">wave</span> function. These basis functions are called complement</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999JChPh.111.7278P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999JChPh.111.7278P"><span>Boundary condition determined <span class="hlt">wave</span> functions for the ground states of one- and two-electron homonuclear molecules</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Patil, S. H.; Tang, K. T.; Toennies, J. P.</p> <p>1999-10-01</p> <p>Simple analytical <span class="hlt">wave</span> functions satisfying appropriate boundary conditions are constructed for the ground states of one-and two-electron homonuclear molecules. Both the asymptotic condition when one electron is far away and the cusp condition when the electron coalesces with a nucleus are satisfied by the proposed <span class="hlt">wave</span> function. For H2+, the resulting <span class="hlt">wave</span> function is almost identical to the Guillemin-Zener <span class="hlt">wave</span> function which is known to give very good energies. For the two electron systems H2 and He2++, the additional electron-electron cusp condition is rigorously accounted for by a simple analytic correlation function which has the correct behavior not only for r12→0 and r12→∞ but also for R→0 and R→∞, where r12 is the interelectronic distance and R, the internuclear distance. Energies obtained from these simple <span class="hlt">wave</span> functions agree within 2×10-3 a.u. with the results of the most sophisticated <span class="hlt">variational</span> calculations for all R and for all systems studied. This demonstrates that rather simple physical considerations can be used to derive very <span class="hlt">accurate</span> <span class="hlt">wave</span> functions for simple molecules thereby avoiding laborious numerical <span class="hlt">variational</span> calculations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/538465-anomalous-width-variations-ion-acoustic-rarefactive-solitary-waves-warm-ion-plasma-two-electron-temperatures','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/538465-anomalous-width-variations-ion-acoustic-rarefactive-solitary-waves-warm-ion-plasma-two-electron-temperatures"><span>Anomalous width <span class="hlt">variations</span> for ion acoustic rarefactive solitary <span class="hlt">waves</span> in a warm ion plasma with two electron temperatures</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Ghosh, S.S.; Sekar Iyengar, A.N.</p> <p>1997-09-01</p> <p>Anomalous width{endash}amplitude <span class="hlt">variations</span> were observed in large amplitude rarefactive solitary <span class="hlt">waves</span> which show increasing width with increasing amplitude, contrasting the usual reciprocal relation between the square of the width and the amplitude, beyond a certain value of the plasma parameters [S. S. Ghosh, K. K. Ghosh, and A. N. Sekar Iyengar, Phys. Plasmas, {bold 3}, 3939 (1996)]. For the limiting maximum amplitude, the {open_quotes}increasing width{close_quotes} solitary <span class="hlt">wave</span> tends to a double layer-like solution. The overall <span class="hlt">variation</span> was found to depend crucially on the specific parameter space. From a detailed investigation of the above behavior, a plausible physical explanation has beenmore » presented for such increases in the width. It is found that the ions{close_quote} initial kinetic energies and the cold electron concentration within the perturbed region play a significant role in determining the observed width{endash}amplitude <span class="hlt">variation</span>. This contradicts the investigation of Sayal, Yadav, and Sharma [Phys. Scr. {bold 47}, 576 (1993)]. {copyright} {ital 1997 American Institute of Physics.}« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1807953','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1807953"><span><span class="hlt">Accurate</span>, high-throughput typing of copy number <span class="hlt">variation</span> using paralogue ratios from dispersed repeats</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Armour, John A. L.; Palla, Raquel; Zeeuwen, Patrick L. J. M.; den Heijer, Martin; Schalkwijk, Joost; Hollox, Edward J.</p> <p>2007-01-01</p> <p>Recent work has demonstrated an unexpected prevalence of copy number <span class="hlt">variation</span> in the human genome, and has highlighted the part this <span class="hlt">variation</span> may play in predisposition to common phenotypes. Some important genes vary in number over a high range (e.g. DEFB4, which commonly varies between two and seven copies), and have posed formidable technical challenges for <span class="hlt">accurate</span> copy number typing, so that there are no simple, cheap, high-throughput approaches suitable for large-scale screening. We have developed a simple comparative PCR method based on dispersed repeat sequences, using a single pair of precisely designed primers to amplify products simultaneously from both test and reference loci, which are subsequently distinguished and quantified via internal sequence differences. We have validated the method for the measurement of copy number at DEFB4 by comparison of results from >800 DNA samples with copy number measurements by MAPH/REDVR, MLPA and array-CGH. The new Paralogue Ratio Test (PRT) method can require as little as 10 ng genomic DNA, appears to be comparable in accuracy to the other methods, and for the first time provides a rapid, simple and inexpensive method for copy number analysis, suitable for application to typing thousands of samples in large case-control association studies. PMID:17175532</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AtmEn.107..351B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AtmEn.107..351B"><span>Temporal <span class="hlt">variation</span> of traffic on highways and the development of <span class="hlt">accurate</span> temporal allocation factors for air pollution analyses</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Batterman, Stuart; Cook, Richard; Justin, Thomas</p> <p>2015-04-01</p> <p>Traffic activity encompasses the number, mix, speed and acceleration of vehicles on roadways. The temporal pattern and <span class="hlt">variation</span> of traffic activity reflects vehicle use, congestion and safety issues, and it represents a major influence on emissions and concentrations of traffic-related air pollutants. <span class="hlt">Accurate</span> characterization of vehicle flows is critical in analyzing and modeling urban and local-scale pollutants, especially in near-road environments and traffic corridors. This study describes methods to improve the characterization of temporal <span class="hlt">variation</span> of traffic activity. Annual, monthly, daily and hourly temporal allocation factors (TAFs), which describe the expected temporal <span class="hlt">variation</span> in traffic activity, were developed using four years of hourly traffic activity data recorded at 14 continuous counting stations across the Detroit, Michigan, U.S. region. Five sites also provided vehicle classification. TAF-based models provide a simple means to apportion annual average estimates of traffic volume to hourly estimates. The analysis shows the need to separate TAFs for total and commercial vehicles, and weekdays, Saturdays, Sundays and observed holidays. Using either site-specific or urban-wide TAFs, nearly all of the <span class="hlt">variation</span> in historical traffic activity at the street scale could be explained; unexplained <span class="hlt">variation</span> was attributed to adverse weather, traffic accidents and construction. The methods and results presented in this paper can improve air quality dispersion modeling of mobile sources, and can be used to evaluate and model temporal <span class="hlt">variation</span> in ambient air quality monitoring data and exposure estimates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4380130','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4380130"><span>Temporal <span class="hlt">variation</span> of traffic on highways and the development of <span class="hlt">accurate</span> temporal allocation factors for air pollution analyses</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Batterman, Stuart; Cook, Richard; Justin, Thomas</p> <p>2015-01-01</p> <p>Traffic activity encompasses the number, mix, speed and acceleration of vehicles on roadways. The temporal pattern and <span class="hlt">variation</span> of traffic activity reflects vehicle use, congestion and safety issues, and it represents a major influence on emissions and concentrations of traffic-related air pollutants. <span class="hlt">Accurate</span> characterization of vehicle flows is critical in analyzing and modeling urban and local-scale pollutants, especially in near-road environments and traffic corridors. This study describes methods to improve the characterization of temporal <span class="hlt">variation</span> of traffic activity. Annual, monthly, daily and hourly temporal allocation factors (TAFs), which describe the expected temporal <span class="hlt">variation</span> in traffic activity, were developed using four years of hourly traffic activity data recorded at 14 continuous counting stations across the Detroit, Michigan, U.S. region. Five sites also provided vehicle classification. TAF-based models provide a simple means to apportion annual average estimates of traffic volume to hourly estimates. The analysis shows the need to separate TAFs for total and commercial vehicles, and weekdays, Saturdays, Sundays and observed holidays. Using either site-specific or urban-wide TAFs, nearly all of the <span class="hlt">variation</span> in historical traffic activity at the street scale could be explained; unexplained <span class="hlt">variation</span> was attributed to adverse weather, traffic accidents and construction. The methods and results presented in this paper can improve air quality dispersion modeling of mobile sources, and can be used to evaluate and model temporal <span class="hlt">variation</span> in ambient air quality monitoring data and exposure estimates. PMID:25844042</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850045117&hterms=potential+action&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dpotential%2Baction','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850045117&hterms=potential+action&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dpotential%2Baction"><span>Conservation laws of <span class="hlt">wave</span> action and potential enstrophy for Rossby <span class="hlt">waves</span> in a stratified atmosphere</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Straus, D. M.</p> <p>1983-01-01</p> <p>The evolution of <span class="hlt">wave</span> energy, enstrophy, and <span class="hlt">wave</span> motion for atmospheric Rossby <span class="hlt">waves</span> in a variable mean flow are discussed from a theoretical and pedagogic standpoint. In the absence of mean flow gradients, the <span class="hlt">wave</span> energy density satisfies a local conservation law, with the appropriate flow velocity being the group velocity. In the presence of mean flow <span class="hlt">variations</span>, <span class="hlt">wave</span> energy is not conserved, but <span class="hlt">wave</span> action is, provided the mean flow is independent of longitude. <span class="hlt">Wave</span> enstrophy is conserved for arbitrary <span class="hlt">variations</span> of the mean flow. Connections with Eiiassen-Palm flux are also discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840023768','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840023768"><span>Conservation laws of <span class="hlt">wave</span> action and potential enstrophy for Rossby <span class="hlt">waves</span> in a stratified atmosphere</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Straus, D. M.</p> <p>1983-01-01</p> <p>The evolution of <span class="hlt">wave</span> energy, enstrophy, and <span class="hlt">wave</span> motion for atmospheric Rossby <span class="hlt">waves</span> in a variable mean flow are discussed from a theoretical and pedagogic standpoint. In the absence of mean flow gradients, the <span class="hlt">wave</span> energy density satisfies a local conservation law, with the appropriate flow velocity being the group velocity. In the presence of mean flow <span class="hlt">variations</span>, <span class="hlt">wave</span> energy is not conserved, but <span class="hlt">wave</span> action is, provided the mean flow is independent of longitude. <span class="hlt">Wave</span> enstrophy is conserved for arbitrary <span class="hlt">variations</span> of the mean flow. Connections with Eliassen-Palm flux are also discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28619023','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28619023"><span>Potential for adaptation to climate change: family-level <span class="hlt">variation</span> in fitness-related traits and their responses to heat <span class="hlt">waves</span> in a snail population.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Leicht, Katja; Seppälä, Katri; Seppälä, Otto</p> <p>2017-06-15</p> <p>On-going global climate change poses a serious threat for natural populations unless they are able to evolutionarily adapt to changing environmental conditions (e.g. increasing average temperatures, occurrence of extreme weather events). A prerequisite for evolutionary change is within-population heritable genetic <span class="hlt">variation</span> in traits subject to selection. In relation to climate change, mainly phenological traits as well as heat and desiccation resistance have been examined for such <span class="hlt">variation</span>. Therefore, it is important to investigate adaptive potential under climate change conditions across a broader range of traits. This is especially true for life-history traits and defences against natural enemies (e.g. parasites) since they influence organisms' fitness both directly and through species interactions. We examined the adaptive potential of fitness-related traits and their responses to heat <span class="hlt">waves</span> in a population of a freshwater snail, Lymnaea stagnalis. We estimated family-level <span class="hlt">variation</span> and covariation in life history (size, reproduction) and constitutive immune defence traits [haemocyte concentration, phenoloxidase (PO)-like activity, antibacterial activity of haemolymph] in snails experimentally exposed to typical (15 °C) and heat <span class="hlt">wave</span> (25 °C) temperatures. We also assessed <span class="hlt">variation</span> in the reaction norms of these traits between the treatments. We found that at the heat <span class="hlt">wave</span> temperature, snails were larger and reproduced more, while their immune defence was reduced. Snails showed high family-level <span class="hlt">variation</span> in all examined traits within both temperature treatments. The only negative genetic correlation (between reproduction and antibacterial activity) appeared at the high temperature. However, we found no family-level <span class="hlt">variation</span> in the responses of most examined traits to the experimental heat <span class="hlt">wave</span> (i.e. largely parallel reaction norms between the treatments). Only the reduction of PO-like activity when exposed to the high temperature showed family</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMOS21F..06C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMOS21F..06C"><span><span class="hlt">Wave</span> energy converter effects on <span class="hlt">wave</span> propagation: A sensitivity study in Monterey Bay, CA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chang, G.; Jones, C. A.; Roberts, J.; Magalen, J.; Ruehl, K.; Chartrand, C.</p> <p>2014-12-01</p> <p>The development of renewable offshore energy in the United States is growing rapidly and <span class="hlt">wave</span> energy is one of the largest resources currently being evaluated. The deployment of <span class="hlt">wave</span> energy converter (WEC) arrays required to harness this resource could feasibly number in the hundreds of individual devices. The WEC arrays have the potential to alter nearshore <span class="hlt">wave</span> propagation and circulation patterns and ecosystem processes. As the industry progresses from pilot- to commercial-scale it is important to understand and quantify the effects of WECs on the natural nearshore processes that support a local, healthy ecosystem. To help accelerate the realization of commercial-scale <span class="hlt">wave</span> power, predictive modeling tools have been developed and utilized to evaluate the likelihood of environmental impact. At present, direct measurements of the effects of different types of WEC arrays on nearshore <span class="hlt">wave</span> propagation are not available; therefore <span class="hlt">wave</span> model simulations provide the groundwork for investigations of the sensitivity of model results to prescribed WEC characteristics over a range of anticipated <span class="hlt">wave</span> conditions. The present study incorporates a modified version of an industry standard <span class="hlt">wave</span> modeling tool, SWAN (Simulating <span class="hlt">WAves</span> Nearshore), to simulate <span class="hlt">wave</span> propagation through a hypothetical WEC array deployment site on the California coast. The modified SWAN, referred to as SNL-SWAN, incorporates device-specific WEC power take-off characteristics to more <span class="hlt">accurately</span> evaluate a WEC device's effects on <span class="hlt">wave</span> propagation. The primary objectives were to investigate the effects of a range of WEC devices and device and array characteristics (e.g., device spacing, number of WECs in an array) on nearshore <span class="hlt">wave</span> propagation using SNL-SWAN model simulations. Results showed that significant <span class="hlt">wave</span> height was most sensitive to <span class="hlt">variations</span> in WEC device type and size and the number of WEC devices in an array. Locations in the lee centerline of the arrays in each modeled scenario showed the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3920371','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3920371"><span>Molecular Properties by Quantum Monte Carlo: An Investigation on the Role of the <span class="hlt">Wave</span> Function Ansatz and the Basis Set in the Water Molecule</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Zen, Andrea; Luo, Ye; Sorella, Sandro; Guidoni, Leonardo</p> <p>2014-01-01</p> <p>Quantum Monte Carlo methods are <span class="hlt">accurate</span> and promising many body techniques for electronic structure calculations which, in the last years, are encountering a growing interest thanks to their favorable scaling with the system size and their efficient parallelization, particularly suited for the modern high performance computing facilities. The ansatz of the <span class="hlt">wave</span> function and its <span class="hlt">variational</span> flexibility are crucial points for both the <span class="hlt">accurate</span> description of molecular properties and the capabilities of the method to tackle large systems. In this paper, we extensively analyze, using different <span class="hlt">variational</span> ansatzes, several properties of the water molecule, namely, the total energy, the dipole and quadrupole momenta, the ionization and atomization energies, the equilibrium configuration, and the harmonic and fundamental frequencies of vibration. The investigation mainly focuses on <span class="hlt">variational</span> Monte Carlo calculations, although several lattice regularized diffusion Monte Carlo calculations are also reported. Through a systematic study, we provide a useful guide to the choice of the <span class="hlt">wave</span> function, the pseudopotential, and the basis set for QMC calculations. We also introduce a new method for the computation of forces with finite variance on open systems and a new strategy for the definition of the atomic orbitals involved in the Jastrow-Antisymmetrised Geminal power <span class="hlt">wave</span> function, in order to drastically reduce the number of <span class="hlt">variational</span> parameters. This scheme significantly improves the efficiency of QMC energy minimization in case of large basis sets. PMID:24526929</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4721527','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4721527"><span>Shear <span class="hlt">Wave</span> Arrival Time Estimates Correlate with Local Speckle Pattern</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>McAleavey, Stephen A.; Osapoetra, Laurentius O.; Langdon, Jonathan</p> <p>2016-01-01</p> <p>We present simulation and phantom studies demonstrating a strong correlation between errors in shear <span class="hlt">wave</span> arrival time estimates and the lateral position of the local speckle pattern in targets with fully developed speckle. We hypothesize that the observed arrival time <span class="hlt">variations</span> are largely due to the underlying speckle pattern, and call the effect speckle bias. Arrival time estimation is a key step in quantitative shear <span class="hlt">wave</span> elastography, performed by tracking tissue motion via cross correlation of RF ultrasound echoes or similar methods. <span class="hlt">Variations</span> in scatterer strength and interference of echoes from scatterers within the tracking beam result in an echo that does not necessarily describe the average motion within the beam, but one favoring areas of constructive interference and strong scattering. A swept-receive image, formed by fixing the transmit beam and sweeping the receive aperture over the region of interest, is used to estimate the local speckle pattern. Metrics for the lateral position of the speckle are found to correlate strongly (r>0.7) with the estimated shear <span class="hlt">wave</span> arrival times both in simulations and in phantoms. Lateral weighting of the swept-receive pattern improved the correlation between arrival time estimates and speckle position. The simulations indicate that high RF echo correlation does not equate to an <span class="hlt">accurate</span> shear <span class="hlt">wave</span> arrival time estimate – a high correlation coefficient indicates that motion is being tracked with high precision, but the location tracked is uncertain within the tracking beam width. The presence of a strong on-axis speckle is seen to imply high RF correlation and low bias. The converse does not appear to be true – highly correlated RF echoes can still produce biased arrival time estimates. The shear <span class="hlt">wave</span> arrival time bias is relatively stable with <span class="hlt">variations</span> in shear <span class="hlt">wave</span> amplitude and sign (−20 μm to 20 μm simulated) compared to the <span class="hlt">variation</span> with different speckle realizations obtained along a given tracking</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016R%26QE...59..519V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016R%26QE...59..519V"><span><span class="hlt">Wave</span> Effects Related to Altitude <span class="hlt">Variations</span> in the Ion Composition of the Ionosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vavilov, D. I.; Shklyar, D. R.</p> <p>2016-12-01</p> <p>Properties of the <span class="hlt">waves</span>, which can propagate in a magnetized plasma in the frequency range below the proton gyrofrequency, depend strongly on the ion composition of the plasma. Addition of a new sort of ions leads to the appearance of a new resonance frequency, at which the refractive index becomes infinite, and a new cutoff frequency, at which the refractive index becomes zero. In this case, the topology of frequency dependence of the squared refractive index changes. Specifically, a new oscillation branch appears, which is located above the cutoff frequency. A question arises whether these oscillations are excited if radiation with the corresponding frequency, which propagates in a different mode, is present in the plasma. A linear transformation of the <span class="hlt">waves</span> is another important effect, which is related to <span class="hlt">variations</span> in the ion plasma composition. These two issues, which are directly related to the theory of formation of proton whistlers in the ionosphere, where the ion composition varies with altitude, are considered in this work.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1409055-geometric-theory-waves-its-applications-plasma-physics','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1409055-geometric-theory-waves-its-applications-plasma-physics"><span>A geometric theory of <span class="hlt">waves</span> and its applications to plasma physics.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Ruiz, Daniel</p> <p></p> <p><span class="hlt">Waves</span> play an essential role in many aspects of plasma dynamics. For example, they are indispensable in plasma manipulation and diagnostics. Although the physics of <span class="hlt">waves</span> is well understood in the context of relatively simple problems, difficulties arise when studying <span class="hlt">waves</span> that propagate in inhomogeneous or nonlinear media. This thesis presents a new systematic <span class="hlt">wave</span> theory based on phase-space <span class="hlt">variational</span> principles. In this dissertation, <span class="hlt">waves</span> are treated as geometric objects of a <span class="hlt">variational</span> theory rather than formal solutions of specific PDEs. This approach simplifies calculations, highlights the underlying <span class="hlt">wave</span> symmetries, and leads to improved modeling of <span class="hlt">wave</span> dynamics. Specifically, thismore » dissertation presents two important breakthroughs that were obtained in the general theory of <span class="hlt">waves</span>. The first main contribution of the present dissertation is an extension of the theory of geometrical optics (GO) in order to include polarization effects. Even when diffraction is ignored, the GO ray equations are not entirely <span class="hlt">accurate</span>. This occurs because GO treats <span class="hlt">wave</span> rays as classical particles described by their position and momentum coordinates. However, vector <span class="hlt">waves</span> have another degree of freedom, their polarization. As a result, <span class="hlt">wave</span> rays can behave as particles with spin and show polarization dynamics, such as polarization precession and polarization-driven bending of ray trajectories. In this thesis, the theory of GO is reformulated as a first-principle Lagrangian <span class="hlt">wave</span> theory that governs both mentioned polarization phenomena simultaneously. The theory was applied successfully to several systems of interest, such as relativistic spin-$1/2$ particles and radio-frequency <span class="hlt">waves</span> propagating in magnetized plasmas. The second main contribution of this thesis is the development of a phase-space method to study basic properties of nonlinear <span class="hlt">wave--wave</span> interactions. Specifically, a general theory is proposed that describes the ponderomotive refraction that a <span class="hlt">wave</span> can</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002JCli...15.1659H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002JCli...15.1659H"><span>Interannual and Decadal <span class="hlt">Variations</span> of Planetary <span class="hlt">Wave</span> Activity, Stratospheric Cooling, and Northern Hemisphere Annular Mode.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hu, Yongyun; Kit Tung, Ka</p> <p>2002-07-01</p> <p>Using NCEP-NCAR 51-yr reanalysis data, the interannual and decadal <span class="hlt">variations</span> of planetary <span class="hlt">wave</span> activity and its relationship to stratospheric cooling, and the Northern Hemisphere Annular mode (NAM), are studied. It is found that winter stratospheric polar temperature is highly correlated on a year-to-year basis with the Eliassen-Palm (E-P) <span class="hlt">wave</span> flux from the troposphere, implying a dynamical control of the former by the latter, as often suggested. Greater (lower) <span class="hlt">wave</span> activity from the troposphere implies larger (smaller) poleward heat flux into the polar region, which leads to warmer (colder) polar temperature. A similar highly correlated antiphase relationship holds for E-P flux divergence and the strength of the polar vortex in the stratosphere. It is tempting to extrapolate these relationships found for interannual timescales to explain the recent stratospheric polar cooling trend in the past few decades as caused by decreased <span class="hlt">wave</span> activity in the polar region. This speculation is not supported by the data. On timescales of decades the cooling trend is not correlated with the trend in planetary <span class="hlt">wave</span> activity. In fact, it is found that planetary <span class="hlt">wave</span> amplitude, E-P flux, and E-P flux convergence all show little statistical evidence of decrease in the past 51 yr, while the stratosphere is experiencing a cooling trend and the NAM index has a positive trend during the past 30 yr. This suggests that the trends in the winter polar temperature and the NAM index can reasonably be attributed to the radiative cooling of the stratosphere, due possibly to increasing greenhouse gases and ozone depletion. It is further shown that the positive trend of the NAM index in the past few decades is not through the inhibition of upward planetary <span class="hlt">wave</span> propagation from the troposphere to the stratosphere, as previously suggested.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28365237','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28365237"><span>Contributions of aortic pulse <span class="hlt">wave</span> velocity and backward <span class="hlt">wave</span> pressure to <span class="hlt">variations</span> in left ventricular mass are independent of each other.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bello, Hamza; Norton, Gavin R; Ballim, Imraan; Libhaber, Carlos D; Sareli, Pinhas; Woodiwiss, Angela J</p> <p>2017-05-01</p> <p>Aortic pulse <span class="hlt">wave</span> velocity (PWV) and backward <span class="hlt">waves</span>, as determined from <span class="hlt">wave</span> separation analysis, predict cardiovascular events beyond brachial blood pressure. However, the extent to which these aortic hemodynamic variables contribute independent of each other is uncertain. In 749 randomly selected participants of African ancestry, we therefore assessed the extent to which relationships between aortic PWV or backward <span class="hlt">wave</span> pressures (Pb) (and hence central aortic pulse pressure [PPc]) and left ventricular mass index (LVMI) occur independent of each other. Aortic PWV, PPc, forward <span class="hlt">wave</span> pressure (Pf), and Pb were determined using radial applanation tonometry and SphygmoCor software and LVMI using echocardiography; 44.5% of participants had an increased left ventricular mass indexed to height 1.7 . With adjustments for age, brachial systolic blood pressure or PP, and additional confounders, PPc and Pb, but not Pf, were independently related to LVMI and left ventricular hypertrophy (LVH) in both men and women. However, PWV was independently associated with LVMI in women (partial r = 0.16, P < .001), but not in men (partial r = 0.03), and PWV was independently associated with LVH in women (P < .05), but not in men (P = .07). With PWV and Pb included in the same multivariate regression models, PWV (partial r = 0.14, P < .005) and Pb (partial r = 0.10, P < .05) contributed to a similar extent to <span class="hlt">variations</span> in LVMI in women. In addition, with PWV and Pb included in the same multivariate regression models, PWV (P < .05) and Pb (P < .02) contributed to LVH in women. In conclusion, aortic PWV and Pb (and hence pulse pressure) although both associated with LVMI and LVH produce effects which are independent of each other. Copyright © 2017 American Society of Hypertension. Published by Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JCoPh.348..343B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JCoPh.348..343B"><span>An <span class="hlt">accurate</span> boundary element method for the exterior elastic scattering problem in two dimensions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bao, Gang; Xu, Liwei; Yin, Tao</p> <p>2017-11-01</p> <p>This paper is concerned with a Galerkin boundary element method solving the two dimensional exterior elastic <span class="hlt">wave</span> scattering problem. The original problem is first reduced to the so-called Burton-Miller [1] boundary integral formulation, and essential mathematical features of its <span class="hlt">variational</span> form are discussed. In numerical implementations, a newly-derived and analytically <span class="hlt">accurate</span> regularization formula [2] is employed for the numerical evaluation of hyper-singular boundary integral operator. A new computational approach is employed based on the series expansions of Hankel functions for the computation of weakly-singular boundary integral operators during the reduction of corresponding Galerkin equations into a discrete linear system. The effectiveness of proposed numerical methods is demonstrated using several numerical examples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25152218','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25152218"><span>Spreading speeds for plant populations in landscapes with low environmental <span class="hlt">variation</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gilbert, Mark A; Gaffney, Eamonn A; Bullock, James M; White, Steven M</p> <p>2014-12-21</p> <p>) <span class="hlt">variation</span> can be positive or negative, which is in contrast to the reduction in <span class="hlt">wave</span>-speed caused by intrinsic stochasticity. To deal with the loss of accuracy as ϵ increases, we formulate a second-order approximation to the <span class="hlt">wave</span>-speed for periodic landscapes and compare both approximations against the results of numerical simulation and show that they are both <span class="hlt">accurate</span> for the range of landscapes considered. Copyright © 2014 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JSeis..17.1321T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JSeis..17.1321T"><span>Crustal thickness <span class="hlt">variations</span> in the Zagros continental collision zone (Iran) from joint inversion of receiver functions and surface <span class="hlt">wave</span> dispersion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tatar, M.; Nasrabadi, A.</p> <p>2013-10-01</p> <p><span class="hlt">Variations</span> in crustal thickness in the Zagros determined by joint inversion of P <span class="hlt">wave</span> receiver functions (RFs) and Rayleigh <span class="hlt">wave</span> group and phase velocity dispersion. The time domain iterative deconvolution procedure was employed to compute RFs from teleseismic recordings at seven broadband stations of INSN network. Rayleigh <span class="hlt">wave</span> phase velocity dispersion curves were estimated employing two-station method. Fundamental mode Rayleigh <span class="hlt">wave</span> group velocities for each station is taken from a regional scale surface <span class="hlt">wave</span> tomographic imaging. The main <span class="hlt">variations</span> in crustal thickness that we observe are between stations located in the Zagros fold and thrust belt with those located in the Sanandaj-Sirjan zone (SSZ) and Urumieh-Dokhtar magmatic assemblage (UDMA). Our results indicate that the average crustal thickness beneath the Zagros Mountain Range varies from ˜46 km in Western and Central Zagros beneath SHGR and GHIR up to ˜50 km beneath BNDS located in easternmost of the Zagros. Toward NE, we observe an increase in Moho depth where it reaches ˜58 km beneath SNGE located in the SSZ. Average crustal thickness also varies beneath the UDMA from ˜50 km in western parts below ASAO to ˜58 in central parts below NASN. The observed <span class="hlt">variation</span> along the SSZ and UDMA may be associated to ongoing slab steepening or break off in the NW Zagros, comparing under thrusting of the Arabian plate beneath Central Zagros. The results show that in Central Iran, the crustal thickness decrease again to ˜47 km below KRBR. There is not a significant crustal thickness difference along the Zagros fold and thrust belt. We found the same crystalline crust of ˜34 km thick beneath the different parts of the Zagros fold and thrust belt. The similarity of crustal structure suggests that the crust of the Zagros fold and thrust belt was uniform before subsidence and deposition of the sediments. Our results confirm that the shortening of the western and eastern parts of the Zagros basement is small and</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_7 --> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070030190','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070030190"><span>Comparing the Robustness of High-Frequency Traveling-<span class="hlt">Wave</span> Tube Slow-<span class="hlt">Wave</span> Circuits</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chevalier, Christine T.; Wilson, Jeffrey D.; Kory, Carol L.</p> <p>2007-01-01</p> <p>A three-dimensional electromagnetic field simulation software package was used to compute the cold-test parameters, phase velocity, on-axis interaction impedance, and attenuation, for several high-frequency traveling-<span class="hlt">wave</span> tube slow-<span class="hlt">wave</span> circuit geometries. This research effort determined the effects of <span class="hlt">variations</span> in circuit dimensions on cold-test performance. The parameter <span class="hlt">variations</span> were based on the tolerances of conventional micromachining techniques.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26575902','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26575902"><span><span class="hlt">Variational</span> Optimization of the Second-Order Density Matrix Corresponding to a Seniority-Zero Configuration Interaction <span class="hlt">Wave</span> Function.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Poelmans, Ward; Van Raemdonck, Mario; Verstichel, Brecht; De Baerdemacker, Stijn; Torre, Alicia; Lain, Luis; Massaccesi, Gustavo E; Alcoba, Diego R; Bultinck, Patrick; Van Neck, Dimitri</p> <p>2015-09-08</p> <p>We perform a direct <span class="hlt">variational</span> determination of the second-order (two-particle) density matrix corresponding to a many-electron system, under a restricted set of the two-index N-representability P-, Q-, and G-conditions. In addition, we impose a set of necessary constraints that the two-particle density matrix must be derivable from a doubly occupied many-electron <span class="hlt">wave</span> function, i.e., a singlet <span class="hlt">wave</span> function for which the Slater determinant decomposition only contains determinants in which spatial orbitals are doubly occupied. We rederive the two-index N-representability conditions first found by Weinhold and Wilson and apply them to various benchmark systems (linear hydrogen chains, He, N2, and CN(-)). This work is motivated by the fact that a doubly occupied many-electron <span class="hlt">wave</span> function captures in many cases the bulk of the static correlation. Compared to the general case, the structure of doubly occupied two-particle density matrices causes the associate semidefinite program to have a very favorable scaling as L(3), where L is the number of spatial orbitals. Since the doubly occupied Hilbert space depends on the choice of the orbitals, <span class="hlt">variational</span> calculation steps of the two-particle density matrix are interspersed with orbital-optimization steps (based on Jacobi rotations in the space of the spatial orbitals). We also point to the importance of symmetry breaking of the orbitals when performing calculations in a doubly occupied framework.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SuMi..112..455E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SuMi..112..455E"><span>Rayleigh <span class="hlt">wave</span> behavior in functionally graded magneto-electro-elastic material</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ezzin, Hamdi; Mkaoir, Mohamed; Amor, Morched Ben</p> <p>2017-12-01</p> <p>Piezoelectric-piezomagnetic functionally graded materials, with a gradual change of the mechanical and electromagnetic properties have greatly applying promises. Based on the ordinary differential equation and stiffness matrix methods, a dynamic solution is presented for the propagation of the <span class="hlt">wave</span> on a semi-infinite piezomagnetic substrate covered with a functionally graded piezoelectric material (FGPM) layer. The materials properties are assumed to vary in the direction of the thickness according to a known <span class="hlt">variation</span> law. The phase and group velocity of the Rayleigh <span class="hlt">wave</span> is numerically calculated for the magneto-electrically open and short cases, respectively. The effect of gradient coefficients on the phase velocity, group velocity, coupled magneto-electromechanical factor, on the stress fields, the magnetic potential and the mechanical displacement are discussed, respectively. Illustration is achieved on the hetero-structure PZT-5A/CoFe2O4; the obtained results are especially useful in the design of high-performance acoustic surface devices and <span class="hlt">accurately</span> prediction of the Rayleigh <span class="hlt">wave</span> propagation behavior.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JQSRT.133..235S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JQSRT.133..235S"><span>Does <span class="hlt">variation</span> in mineral composition alter the short-<span class="hlt">wave</span> light scattering properties of desert dust aerosol?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, Andrew J. A.; Grainger, Roy G.</p> <p>2014-01-01</p> <p>Mineral dust aerosol is a major component of natural airborne particulates. Using satellite measurements from the visible and near-infrared, there is insufficient information to retrieve a full microphysical and chemical description of an aerosol distribution. As such, refractive index is one of many parameters that must be implicitly assumed in order to obtain an optical depth retrieval. This is essentially a proxy for the dust mineralogy. Using a global soil map, it is shown that as long as a reasonable refractive index for dust is assumed, global dust variability is unlikely to cause significant <span class="hlt">variation</span> in the optical properties of a dust aerosol distribution in the short-<span class="hlt">wave</span>, and so should not greatly affect retrievals of mineral dust aerosol from space by visible and near-infrared radiometers. Errors in aerosol optical depth due to this <span class="hlt">variation</span> are expected to be ≲ 1 %. The work is framed around the ORAC AATSR aerosol retrieval, but is equally applicable to similar satellite retrievals. In this case, <span class="hlt">variations</span> in the top-of-atmosphere reflectance caused by mineral <span class="hlt">variation</span> are within the noise limits of the instrument.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010059955&hterms=Qbo&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DQbo','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010059955&hterms=Qbo&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DQbo"><span>Downward Link of Solar Activity <span class="hlt">Variations</span> Through <span class="hlt">Wave</span> Driven Equatorial Oscillations (QBO and SAO)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mengel, J. G.; Mayr, H. G.; Chan, K. L.; Porter, H. S.; Einaudi, Franco (Technical Monitor)</p> <p>2000-01-01</p> <p>Signatures of the 11-year solar activity/irradiance cycle are observed in the Quasi Biennial Oscillation (QBO) of the lower stratosphere. At these altitudes, the QBO is understood to be the result of "downward control" exerted by the <span class="hlt">wave</span> mean flow interactions that drive the phenomenon. It is reasonable then to speculate that the QBO is a natural conduit to lower altitudes of solar activity <span class="hlt">variations</span> in radiance (SAV). To test this hypothesis, we conducted experiments with a 2D version of our Numerical Spectral Model that incorporates Hines' Doppler Spread Parameterization for small-scale gravity <span class="hlt">waves</span> (GW). To account for the SAV, we change the solar heating rate on a logarithmic scale from 0.1% at the surface to 1% at 50 kin to 10% at 100 km. With the same GW flux, we then conduct numerical experiments to evaluate the magnitude of the solar activity irradiance effect (SAE) on the zonal circulation at low latitudes. The numerical results obtained show that, under certain conditions, the SAE is significant in the zonal circulation and does extend to lower altitudes where the SAV is small. The differences in the wind velocities can be as large as 5 m/s at 20 kin. We carried out two numerical experiments with integrations over more than 20 years: 1) With the QBO period "tuned" to be 30 months, of academic interest but instructive, the seasonal cycle in the solar forcing [through the Semi-annual Oscillation (SAO)] acts as a strong pacemaker to produce a firm lock on the period and phase of the QBO. The SAE then shows up primarily as a distinct but relatively weak amplitude modulation. 2) With the QBO period between 30 and 34 (or less than 30, presumably) months, the seasonal phase lock is weak compared with (1). The SAV in the seasonal cycle then causes <span class="hlt">variations</span> in the QBO period and phase, and this amplifies the SAE to produce relatively large <span class="hlt">variations</span> in the wind field. We conclude that, under realistic conditions as in (2), the solar seasonal forcing, with</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26295501','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26295501"><span>Cyclic Square <span class="hlt">Wave</span> Voltammetry of Surface-Confined Quasireversible Electron Transfer Reactions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mann, Megan A; Bottomley, Lawrence A</p> <p>2015-09-01</p> <p>The theory for cyclic square <span class="hlt">wave</span> voltammetry of surface-confined quasireversible electrode reactions is presented and experimentally verified. Theoretical voltammograms were calculated following systematic <span class="hlt">variation</span> of empirical parameters to assess their impact on the shape of the voltammogram. From the trends obtained, diagnostic criteria for this mechanism were deduced. These criteria were experimentally confirmed using two well-established surface-confined analytes. When properly applied, these criteria will enable non-experts in voltammetry to assign the electrode reaction mechanism and <span class="hlt">accurately</span> measure electrode reaction kinetics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AIPA....5i7179J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AIPA....5i7179J"><span>Significance of <span class="hlt">accurate</span> diffraction corrections for the second harmonic <span class="hlt">wave</span> in determining the acoustic nonlinearity parameter</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jeong, Hyunjo; Zhang, Shuzeng; Barnard, Dan; Li, Xiongbing</p> <p>2015-09-01</p> <p>The <span class="hlt">accurate</span> measurement of acoustic nonlinearity parameter β for fluids or solids generally requires making corrections for diffraction effects due to finite size geometry of transmitter and receiver. These effects are well known in linear acoustics, while those for second harmonic <span class="hlt">waves</span> have not been well addressed and therefore not properly considered in previous studies. In this work, we explicitly define the attenuation and diffraction corrections using the multi-Gaussian beam (MGB) equations which were developed from the quasilinear solutions of the KZK equation. The effects of making these corrections are examined through the simulation of β determination in water. Diffraction corrections are found to have more significant effects than attenuation corrections, and the β values of water can be estimated experimentally with less than 5% errors when the exact second harmonic diffraction corrections are used together with the negligible attenuation correction effects on the basis of linear frequency dependence between attenuation coefficients, α2 ≃ 2α1.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1985PhRvB..31.4267K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1985PhRvB..31.4267K"><span>Theory of inhomogeneous quantum systems. III. <span class="hlt">Variational</span> <span class="hlt">wave</span> functions for Fermi fluids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Krotscheck, E.</p> <p>1985-04-01</p> <p>We develop a general <span class="hlt">variational</span> theory for inhomogeneous Fermi systems such as the electron gas in a metal surface, the surface of liquid 3He, or simple models of heavy nuclei. The ground-state <span class="hlt">wave</span> function is expressed in terms of two-body correlations, a one-body attenuation factor, and a model-system Slater determinant. Massive partial summations of cluster expansions are performed by means of Born-Green-Yvon and hypernetted-chain techniques. An optimal single-particle basis is generated by a generalized Hartree-Fock equation in which the two-body correlations screen the bare interparticle interaction. The optimization of the pair correlations leads to a state-averaged random-phase-approximation equation and a strictly microscopic determination of the particle-hole interaction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26645201','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26645201"><span>Micro-scale environmental <span class="hlt">variation</span> amplifies physiological <span class="hlt">variation</span> among individual mussels.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jimenez, Ana Gabriela; Jayawardene, Sarah; Alves, Shaina; Dallmer, Jeremiah; Dowd, W Wesley</p> <p>2015-12-07</p> <p>The contributions of temporal and spatial environmental <span class="hlt">variation</span> to physiological <span class="hlt">variation</span> remain poorly resolved. Rocky intertidal zone populations are subjected to thermal <span class="hlt">variation</span> over the tidal cycle, superimposed with micro-scale <span class="hlt">variation</span> in individuals' body temperatures. Using the sea mussel (Mytilus californianus), we assessed the consequences of this micro-scale environmental <span class="hlt">variation</span> for physiological <span class="hlt">variation</span> among individuals, first by examining the latter in field-acclimatized animals, second by abolishing micro-scale environmental <span class="hlt">variation</span> via common garden acclimation, and third by restoring this <span class="hlt">variation</span> using a reciprocal outplant approach. Common garden acclimation reduced the magnitude of <span class="hlt">variation</span> in tissue-level antioxidant capacities by approximately 30% among mussels from a <span class="hlt">wave</span>-protected (warm) site, but it had no effect on antioxidant <span class="hlt">variation</span> among mussels from a <span class="hlt">wave</span>-exposed (cool) site. The field-acclimatized level of antioxidant <span class="hlt">variation</span> was restored only when protected-site mussels were outplanted to a high, thermally stressful site. <span class="hlt">Variation</span> in organismal oxygen consumption rates reflected antioxidant patterns, decreasing dramatically among protected-site mussels after common gardening. These results suggest a highly plastic relationship between individuals' genotypes and their physiological phenotypes that depends on recent environmental experience. Corresponding context-dependent changes in the physiological mean-variance relationships within populations complicate prediction of responses to shifts in environmental variability that are anticipated with global change. © 2015 The Author(s).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=function+AND+wave&pg=3&id=EJ794601','ERIC'); return false;" href="https://eric.ed.gov/?q=function+AND+wave&pg=3&id=EJ794601"><span>Accuracy of Satellite-Measured <span class="hlt">Wave</span> Heights in the Australian Region for <span class="hlt">Wave</span> Power Applications</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Meath, Sian E.; Aye, Lu; Haritos, Nicholas</p> <p>2008-01-01</p> <p>This article focuses on the accuracy of satellite data, which may then be used in <span class="hlt">wave</span> power applications. The satellite data are compared to data from <span class="hlt">wave</span> buoys, which are currently considered to be the most <span class="hlt">accurate</span> of the devices available for measuring <span class="hlt">wave</span> characteristics. This article presents an analysis of satellite- (Topex/Poseidon) and…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27782004','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27782004"><span>Robust dynamic myocardial perfusion CT deconvolution for <span class="hlt">accurate</span> residue function estimation via adaptive-weighted tensor total <span class="hlt">variation</span> regularization: a preclinical study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zeng, Dong; Gong, Changfei; Bian, Zhaoying; Huang, Jing; Zhang, Xinyu; Zhang, Hua; Lu, Lijun; Niu, Shanzhou; Zhang, Zhang; Liang, Zhengrong; Feng, Qianjin; Chen, Wufan; Ma, Jianhua</p> <p>2016-11-21</p> <p>Dynamic myocardial perfusion computed tomography (MPCT) is a promising technique for quick diagnosis and risk stratification of coronary artery disease. However, one major drawback of dynamic MPCT imaging is the heavy radiation dose to patients due to its dynamic image acquisition protocol. In this work, to address this issue, we present a robust dynamic MPCT deconvolution algorithm via adaptive-weighted tensor total <span class="hlt">variation</span> (AwTTV) regularization for <span class="hlt">accurate</span> residue function estimation with low-mA s data acquisitions. For simplicity, the presented method is termed 'MPD-AwTTV'. More specifically, the gains of the AwTTV regularization over the original tensor total <span class="hlt">variation</span> regularization are from the anisotropic edge property of the sequential MPCT images. To minimize the associative objective function we propose an efficient iterative optimization strategy with fast convergence rate in the framework of an iterative shrinkage/thresholding algorithm. We validate and evaluate the presented algorithm using both digital XCAT phantom and preclinical porcine data. The preliminary experimental results have demonstrated that the presented MPD-AwTTV deconvolution algorithm can achieve remarkable gains in noise-induced artifact suppression, edge detail preservation, and <span class="hlt">accurate</span> flow-scaled residue function and MPHM estimation as compared with the other existing deconvolution algorithms in digital phantom studies, and similar gains can be obtained in the porcine data experiment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002EGSGA..27.4546E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002EGSGA..27.4546E"><span><span class="hlt">Wave</span> Tank Studies of Strong Modulation of Wind Ripples Due To Long <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ermakov, S.; Sergievskaya, I.; Shchegolkov, Yu.</p> <p></p> <p>Modulation of wind capillary-gravity ripples due to long <span class="hlt">waves</span> has been studied in <span class="hlt">wave</span> tank experiment at low wind speeds using Ka-band radar. The experiments were carried out both for clean water and the water surface covered with surfactant films. It is obtained that the modulation of radar signals is quite strong and can increase with surfactant concentration and fetch. It is shown that the hydrodynamic Modulation Transfer Function (MTF) calculated for free wind ripples and taking into account the kinematic (straining) effect, <span class="hlt">variations</span> of the wind stress and <span class="hlt">variations</span> of surfactant concentration strongly underestimates experimental MTF-values. The effect of strong modulation is assumed to be connected with nonlinear harmonics of longer dm-cm- scale <span class="hlt">waves</span> - bound <span class="hlt">waves</span> ("parasitic ripples"). The intensity of bound <span class="hlt">waves</span> depends strongly on the amplitude of decimetre-scale <span class="hlt">waves</span>, therefore even weak modulation of the dm-scale <span class="hlt">waves</span> due to long <span class="hlt">waves</span> results to strong ("cascade") modulation of bound <span class="hlt">waves</span>. Modulation of the system of "free/bound <span class="hlt">waves</span>" is estimated using results of <span class="hlt">wave</span> tank studies of bound <span class="hlt">waves</span> generation and is shown to be in quali- tative agreement with experiment. This work was supported by MOD, UK via DERA Winfrith (Project ISTC 1774P) and by RFBR (Project 02-05-65102).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/21464553-excitation-parasitic-waves-near-cutoff-forward-wave-amplifiers','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/21464553-excitation-parasitic-waves-near-cutoff-forward-wave-amplifiers"><span>Excitation of parasitic <span class="hlt">waves</span> near cutoff in forward-<span class="hlt">wave</span> amplifiers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Nusinovich, Gregory S.; Sinitsyn, Oleksandr V.; Antonsen, Thomas M. Jr.</p> <p>2010-10-15</p> <p>In this paper, excitation of parasitic <span class="hlt">waves</span> near cutoff in forward-<span class="hlt">wave</span> amplifiers is studied in a rather general form. This problem is important for developing high-power sources of coherent, phase controlled short-wavelength electromagnetic radiation because just the <span class="hlt">waves</span> which can be excited near cutoff have low group velocities. Since the <span class="hlt">wave</span> coupling to an electron beam is inversely proportional to the group velocity, these <span class="hlt">waves</span> are the most dangerous parasitic <span class="hlt">waves</span> preventing stable amplification of desired signal <span class="hlt">waves</span>. Two effects are analyzed in the paper. The first one is the effect of signal <span class="hlt">wave</span> parameters on the self-excitation conditions ofmore » such parasitic <span class="hlt">waves</span>. The second effect is the role of the beam geometry on excitation of these parasitic <span class="hlt">waves</span> in forward-<span class="hlt">wave</span> amplifiers with spatially extended interaction space, such as sheet-beam devices. It is shown that a large-amplitude signal <span class="hlt">wave</span> can greatly influence the self-excitation conditions of the parasitic <span class="hlt">waves</span> which define stability of operation. Therefore the effect described is important for <span class="hlt">accurate</span> designing of high-power amplifiers of electromagnetic <span class="hlt">waves</span>.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24796246','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24796246"><span>Measurement of cylindrical Rayleigh surface <span class="hlt">waves</span> using line-focused PVDF transducers and defocusing measurement method.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lin, Chun-I; Lee, Yung-Chun</p> <p>2014-08-01</p> <p>Line-focused PVDF transducers and defocusing measurement method are applied in this work to determine the dispersion curve of the Rayleigh-like surface <span class="hlt">waves</span> propagating along the circumferential direction of a solid cylinder. Conventional waveform processing method has been modified to cope with the non-linear relationship between phase angle of <span class="hlt">wave</span> interference and defocusing distance induced by a cylindrically curved surface. A cross correlation method is proposed to <span class="hlt">accurately</span> extract the cylindrical Rayleigh <span class="hlt">wave</span> velocity from measured data. Experiments have been carried out on one stainless steel and one glass cylinders. The experimentally obtained dispersion curves are in very good agreement with their theoretical counterparts. <span class="hlt">Variation</span> of cylindrical Rayleigh <span class="hlt">wave</span> velocity due to the cylindrical curvature is quantitatively verified using this new method. Other potential applications of this measurement method for cylindrical samples will be addressed. Copyright © 2014 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19980003967&hterms=la+nasa&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dla%2Bnasa','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19980003967&hterms=la+nasa&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dla%2Bnasa"><span>WINDII atmospheric <span class="hlt">wave</span> airglow imaging</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Armstrong, W. T.; Hoppe, U.-P.; Solheim, B. H.; Shepherd, G. G.</p> <p>1996-01-01</p> <p>Preliminary WINDII nighttime airglow <span class="hlt">wave</span>-imaging data in the UARS rolldown attitude has been analyzed with the goal to survey gravity <span class="hlt">waves</span> near the upper boundary of the middle atmosphere. <span class="hlt">Wave</span> analysis is performed on O[sub 2](0,0) emissions from a selected 1[sup 0] x 1[sup 0] oblique view of the airglow layer at approximately 95 km altitude, which has no direct earth background and only an atmospheric background which is optically thick for the 0[sub 2](0,0) emission. From a small data set, orbital imaging of atmospheric <span class="hlt">wave</span> structures is demonstrated, with indication of large <span class="hlt">variations</span> in <span class="hlt">wave</span> activity across land and sea. Comparison ground-based imagery is discussed with respect to similarity of <span class="hlt">wave</span> <span class="hlt">variations</span> across land/sea boundaries and future orbital mosaic image construction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JASTP.105...30L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JASTP.105...30L"><span>Seasonal <span class="hlt">variation</span> of <span class="hlt">wave</span> activities near the mesopause region observed at King Sejong Station (62.22°S, 58.78°W), Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, Changsup; Kim, Yong Ha; Kim, Jeong-Han; Jee, Geonhwa; Won, Young-In; Wu, Dong L.</p> <p>2013-12-01</p> <p>We analyzed the neutral wind data at altitudes of 80-100 km obtained from a VHF meteor radar at King Sejong Station (KSS, 62.22°S, 58.78°W), a key location to study <span class="hlt">wave</span> activities above the stratospheric vortex near the Antarctic Peninsula. The seasonal behavior of the semidiurnal tides is generally consistent with the prediction of Global Scale <span class="hlt">Wave</span> Model (GSWM02) except in the altitude region above ~96 km. Gravity <span class="hlt">wave</span> (GW) activities inferred from the neutral wind variances show a seasonal <span class="hlt">variation</span> very similar to the semidiurnal tide amplitudes, suggesting a strong interaction between gravity <span class="hlt">waves</span> and the tide. Despite the consistent seasonal <span class="hlt">variations</span> of the GW wind variances observed at the adjacent Rothera station, the magnitudes of the wind variance obtained at KSS are much larger than those at Rothera, especially during May-September. The enhanced GW activity at KSS is also observed by Aura Microwave Limb Sounder (MLS) from space in its temperature variance. The observed large wind variances at KSS imply that the Antarctic vortex in the stratosphere may act as an effective filter and source for the GWs in the upper atmosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSA33A2423T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSA33A2423T"><span>Long-term <span class="hlt">variation</span> of horizontal phase velocity and propagation direction of mesospheric and thermospheric gravity <span class="hlt">waves</span> by using airglow images obtained at Shigarkai, Japan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Takeo, D.; Kazuo, S.; Hujinami, H.; Otsuka, Y.; Matsuda, T. S.; Ejiri, M. K.; Yamamoto, M.; Nakamura, T.</p> <p>2016-12-01</p> <p>Atmospheric gravity <span class="hlt">waves</span> generated in the lower atmosphere transport momentum into the upper atmosphere and release it when they break. The released momentum drives the global-scale pole-to-pole circulation and causes global mass transport. Vertical propagation of the gravity <span class="hlt">waves</span> and transportation of momentum depend on horizontal phase velocity of gravity <span class="hlt">waves</span> according to equation about dispersion relation of <span class="hlt">waves</span>. Horizontal structure of gravity <span class="hlt">waves</span> including horizontal phase velocity can be seen in the airglow images, and there have been many studies about gravity <span class="hlt">waves</span> by using airglow images. However, long-term <span class="hlt">variation</span> of horizontal phase velocity spectrum of gravity <span class="hlt">waves</span> have not been studied yet. In this study, we used 3-D FFT method developed by Matsuda et al., (2014) to analyze the horizontal phase velocity spectrum of gravity <span class="hlt">waves</span> by using 557.7-nm (altitude of 90-100 km) and 630.0-nm (altitude of 200-300 km) airglow images obtained at Shigaraki MU Observatory (34.8 deg N, 136.1 deg E) over 16 years from October 1, 1998 to July 26, 2015. Results about 557.7-nm shows clear seasonal <span class="hlt">variation</span> of propagation direction of gravity <span class="hlt">waves</span> in the mesopause region. Between summer and winter, there are propagation direction anisotropies which probably caused by filtering due to zonal mesospheric jet and by difference of latitudinal location of <span class="hlt">wave</span> sources relative to Shigaraki. Results about 630.0-nm shows clear negative correlation between the yearly power spectrum density of horizontal phase velocity and sunspot number. This negative correlation with solar activity is consistent with growth rate of the Perkins instability, which may play an important role in generating the nighttime medium-scale traveling ionospheric disturbances at middle latitudes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1612316V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1612316V"><span>Seismic <span class="hlt">Wave</span> Propagation in Fully Anisotropic Axisymmetric Media: Applications and Practical Considerations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>van Driel, Martin; Nissen-Meyer, Tarje; Stähler, Simon; Waszek, Lauren; Hempel, Stefanie; Auer, Ludwig; Deuss, Arwen</p> <p>2014-05-01</p> <p>We present a numerical method to compute high-frequency 3D elastic <span class="hlt">waves</span> in fully anisotropic axisymmetric media. The method is based on a decomposition of the wavefield into a series of uncoupled 2D equations, for which the dependence of the wavefield on the azimuth can be solved analytically. The remaining 2D problems are then solved using a spectral element method (AxiSEM). AxiSEM was recently published open-source (Nissen-Meyer et al. 2014) as a production ready code capable to compute global seismic <span class="hlt">wave</span> propagation up to frequencies of ~2Hz. It <span class="hlt">accurately</span> models visco-elastic dissipation and anisotropy (van Driel et al., submitted to GJI) and runs efficiently on HPC resources using up to 10K cores. At very short period, the Fresnel Zone of body <span class="hlt">waves</span> is narrow and sensitivity is focused around the geometrical ray. In cases where the azimuthal <span class="hlt">variations</span> of structural heterogeneity exhibit long spatial wavelengths, so called 2.5D simulations (3D wavefields in 2D models) provide a good approximation. In AxiSEM, twodimensional <span class="hlt">variations</span> in the source-receiver plane are effectively modelled as ringlike structures extending in the out-of-plane direction. In contrast to ray-theory, which is widely used in high-frequency applications, AxiSEM provides complete waveforms, thus giving access to frequency dependency, amplitude <span class="hlt">variations</span>, and peculiar <span class="hlt">wave</span> effects such as diffraction and caustics. Here we focus on the practical implications of the inherent axisymmetric geometry and show how the 2.5D-features of our method method can be used to model realistic anisotropic structures, by applying it to problems such as the D" region and the inner core.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JGRA..117.4313K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JGRA..117.4313K"><span>Planetary and tidal <span class="hlt">wave</span>-type oscillations in the ionospheric sporadic E layers over Tehran region</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Karami, K.; Ghader, S.; Bidokhti, A. A.; Joghataei, M.; Neyestani, A.; Mohammadabadi, A.</p> <p>2012-04-01</p> <p>It is believed that in the lower ionosphere, particularly in the ionospheric sporadic E (Es) layers (90-130 km), the planetary and tidal <span class="hlt">wave</span>-type oscillations in the ionized component indicate the planetary and tidal <span class="hlt">waves</span> in the neutral atmosphere. In the present work, the presence of <span class="hlt">wave</span>-type oscillations, including planetary and tidal <span class="hlt">waves</span> in the ionospheric sporadic E layers over Tehran region is examined. Data measured by a digital ionosonde at the ionospheric station of the Institute of Geophysics, University of Tehran, from July 2006 to June 2007 are used to investigate seasonal <span class="hlt">variations</span> of planetary and tidal <span class="hlt">waves</span> activities. For the purpose of <span class="hlt">accurate</span> comparison between different seasons, wavelet transform is applied to time series of foEs and h‧Es, namely, the critical frequency and virtual height of Es layers, respectively. The results show that the sporadic E layers over Tehran region are strongly under the influence of upward propagation of <span class="hlt">waves</span> from below. More specifically, among diverse range of periodicities in the sporadic E layers, we found that diurnal (24 hours) and semidiurnal (12 hours) oscillations in all seasons for both parameters. Moreover, terdiurnal (8 hours) tide-like <span class="hlt">variation</span> is observed during spring and summer for foEs parameter and summer and winter for h‧Es. Furthermore, the results show that diurnal tidal <span class="hlt">waves</span> obtain their maximum activities during autumn and winter seasons, and their activities decrease during the late spring and summer. In addition, periods of about 2, 4, 6, 10, 14, and 16 days in our observation verifies the hypothesis of upward propagation of planetary <span class="hlt">waves</span> from lower atmosphere to the ionosphere. Moreover, planetary <span class="hlt">waves</span> have their maximum activities during equinox.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JSMME...2..397A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JSMME...2..397A"><span>Stress <span class="hlt">Wave</span> Scattering: Friend or Enemy of Non Destructive Testing of Concrete?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Aggelis, Dimitrios G.; Shiotani, Tomoki; Philippidis, Theodore P.; Polyzos, Demosthenes</p> <p></p> <p>Cementitious materials are by definition inhomogeneous containing cement paste, sand, aggregates as well as air voids. <span class="hlt">Wave</span> propagation in such a material is characterized by scattering phenomena. Damage in the form of micro or macro cracks certainly enhances scattering influence. Its most obvious manifestation is the velocity <span class="hlt">variation</span> with frequency and excessive attenuation. The influence becomes stronger with increased mis-match of elastic properties of constituent materials and higher crack content. Therefore, in many cases of large concrete structures, field application of stress <span class="hlt">waves</span> is hindered since attenuation makes the acquisition of reliable signals troublesome. However, measured <span class="hlt">wave</span> parameters, combined with investigation with scattering theory can reveal much about the internal condition and supply information that cannot be obtained in any other way. The size and properties of the scatterers leave their signature on the dispersion and attenuation curves making thus the characterization more <span class="hlt">accurate</span> in case of damage assessment, repair evaluation as well as composition inspection. In this paper, three indicative cases of scattering influence are presented. Namely, the interaction of actual distributed damage, as well as the repair material injected in an old concrete structure with the <span class="hlt">wave</span> parameters. Other cases are the influence of light plastic inclusions in hardened mortar and the influence of sand and water content in the examination of fresh concrete. In all the above cases, scattering seems to complicate the propagation behavior but also offers the way for a more <span class="hlt">accurate</span> characterization of the quality of the material.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AIPC.1096.1386I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AIPC.1096.1386I"><span>Constant Group Velocity Ultrasonic Guided <span class="hlt">Wave</span> Inspection for Corrosion and Erosion Monitoring in Pipes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Instanes, Geir; Pedersen, Audun; Toppe, Mads; Nagy, Peter B.</p> <p>2009-03-01</p> <p>This paper describes a novel ultrasonic guided <span class="hlt">wave</span> inspection technique for the monitoring of internal corrosion and erosion in pipes, which exploits the fundamental flexural mode to measure the average wall thickness over the inspection path. The inspection frequency is chosen so that the group velocity of the fundamental flexural mode is essentially constant throughout the wall thickness range of interest, while the phase velocity is highly dispersive and changes in a systematic way with varying wall thickness in the pipe. Although this approach is somewhat less <span class="hlt">accurate</span> than the often used transverse resonance methods, it smoothly integrates the wall thickness over the whole propagation length, therefore it is very robust and can tolerate large and uneven thickness <span class="hlt">variations</span> from point to point. The constant group velocity (CGV) method is capable of monitoring the true average of the wall thickness over the inspection length with an accuracy of 1% even in the presence of one order of magnitude larger local <span class="hlt">variations</span>. This method also eliminates spurious <span class="hlt">variations</span> caused by changing temperature, which can cause fairly large velocity <span class="hlt">variations</span>, but do not significantly influence the dispersion as measured by the true phase angle in the vicinity of the CGV point. The CGV guided <span class="hlt">wave</span> CEM method was validated in both laboratory and field tests.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970024921','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970024921"><span>Numerical Assessment of Four-Port Through-Flow <span class="hlt">Wave</span> Rotor Cycles with Passage Height <span class="hlt">Variation</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Paxson, D. E.; Lindau, Jules W.</p> <p>1997-01-01</p> <p>The potential for improved performance of <span class="hlt">wave</span> rotor cycles through the use of passage height <span class="hlt">variation</span> is examined. A Quasi-one-dimensional CFD code with experimentally validated loss models is used to determine the flowfield in the <span class="hlt">wave</span> rotor passages. Results indicate that a carefully chosen passage height profile can produce substantial performance gains. Numerical performance data are presented for a specific profile, in a four-port, through-flow cycle design which yielded a computed 4.6% increase in design point pressure ratio over a comparably sized rotor with constant passage height. In a small gas turbine topping cycle application, this increased pressure ratio would reduce specific fuel consumption to 22% below the un-topped engine; a significant improvement over the already impressive 18% reductions predicted for the constant passage height rotor. The simulation code is briefly described. The method used to obtain rotor passage height profiles with enhanced performance is presented. Design and off-design results are shown using two different computational techniques. The paper concludes with some recommendations for further work.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930017879','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930017879"><span>On the <span class="hlt">accurate</span> long-time solution of the <span class="hlt">wave</span> equation in exterior domains: Asymptotic expansions and corrected boundary conditions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hagstrom, Thomas; Hariharan, S. I.; Maccamy, R. C.</p> <p>1993-01-01</p> <p>We consider the solution of scattering problems for the <span class="hlt">wave</span> equation using approximate boundary conditions at artificial boundaries. These conditions are explicitly viewed as approximations to an exact boundary condition satisfied by the solution on the unbounded domain. We study the short and long term behavior of the error. It is provided that, in two space dimensions, no local in time, constant coefficient boundary operator can lead to <span class="hlt">accurate</span> results uniformly in time for the class of problems we consider. A variable coefficient operator is developed which attains better accuracy (uniformly in time) than is possible with constant coefficient approximations. The theory is illustrated by numerical examples. We also analyze the proposed boundary conditions using energy methods, leading to asymptotically correct error bounds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4856976','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4856976"><span>COSMOS: <span class="hlt">accurate</span> detection of somatic structural <span class="hlt">variations</span> through asymmetric comparison between tumor and normal samples</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Yamagata, Koichi; Yamanishi, Ayako; Kokubu, Chikara; Takeda, Junji; Sese, Jun</p> <p>2016-01-01</p> <p>An important challenge in cancer genomics is precise detection of structural <span class="hlt">variations</span> (SVs) by high-throughput short-read sequencing, which is hampered by the high false discovery rates of existing analysis tools. Here, we propose an <span class="hlt">accurate</span> SV detection method named COSMOS, which compares the statistics of the mapped read pairs in tumor samples with isogenic normal control samples in a distinct asymmetric manner. COSMOS also prioritizes the candidate SVs using strand-specific read-depth information. Performance tests on modeled tumor genomes revealed that COSMOS outperformed existing methods in terms of F-measure. We also applied COSMOS to an experimental mouse cell-based model, in which SVs were induced by genome engineering and gamma-ray irradiation, followed by polymerase chain reaction-based confirmation. The precision of COSMOS was 84.5%, while the next best existing method was 70.4%. Moreover, the sensitivity of COSMOS was the highest, indicating that COSMOS has great potential for cancer genome analysis. PMID:26833260</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.S13B0655K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.S13B0655K"><span>Surface-<span class="hlt">Wave</span> Relocation of Remote Continental Earthquakes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kintner, J. A.; Ammon, C. J.; Cleveland, M.</p> <p>2017-12-01</p> <p><span class="hlt">Accurate</span> hypocenter locations are essential for seismic event analysis. Single-event location estimation methods provide relatively imprecise results in remote regions with few nearby seismic stations. Previous work has demonstrated that improved relative epicentroid precision in oceanic environments is obtainable using surface-<span class="hlt">wave</span> cross correlation measurements. We use intermediate-period regional and teleseismic Rayleigh and Love <span class="hlt">waves</span> to estimate relative epicentroid locations of moderately-sized seismic events in regions around Iran. <span class="hlt">Variations</span> in faulting geometry, depth, and intermediate-period dispersion make surface-<span class="hlt">wave</span> based event relocation challenging across this broad continental region. We compare and integrate surface-<span class="hlt">wave</span> based relative locations with InSAR centroid location estimates. However, mapping an earthquake sequence mainshock to an InSAR fault deformation model centroid is not always a simple process, since the InSAR observations are sensitive to post-seismic deformation. We explore these ideas using earthquake sequences in western Iran. We also apply surface-<span class="hlt">wave</span> relocation to smaller magnitude earthquakes (3.5 < M < 5.0). Inclusion of smaller-magnitude seismic events in a relocation effort requires a shift in bandwidth to shorter periods, which increases the sensitivity of relocations to surface-<span class="hlt">wave</span> dispersion. Frequency-domain inter-event phase observations are used to understand the time-domain cross-correlation information, and to choose the appropriate band for applications using shorter periods. Over short inter-event distances, the changing group velocity does not strongly degrade the relative locations. For small-magnitude seismic events in continental regions, surface-<span class="hlt">wave</span> relocation does not appear simple enough to allow broad routine application, but using this method to analyze individual earthquake sequences can provide valuable insight into earthquake and faulting processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRA..123.4329R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRA..123.4329R"><span>Tsunami <span class="hlt">Wave</span> Height Estimation from GPS-Derived Ionospheric Data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rakoto, Virgile; Lognonné, Philippe; Rolland, Lucie; Coïsson, P.</p> <p>2018-05-01</p> <p>Large underwater earthquakes (Mw>7) can transmit part of their energy to the surrounding ocean through large seafloor motions, generating tsunamis that propagate over long distances. The forcing effect of tsunami <span class="hlt">waves</span> on the atmosphere generates internal gravity <span class="hlt">waves</span> that, when they reach the upper atmosphere, produce ionospheric perturbations. These perturbations are frequently observed in the total electron content (TEC) measured by multifrequency Global Navigation Satellite Systems (GNSS) such as GPS, GLONASS, and, in the future, Galileo. This paper describes the first inversion of the <span class="hlt">variation</span> in sea level derived from GPS TEC data. We used a least squares inversion through a normal-mode summation modeling. This technique was applied to three tsunamis in far field associated to the 2012 Haida Gwaii, 2006 Kuril Islands, and 2011 Tohoku events and for Tohoku also in close field. With the exception of the Tohoku far-field case, for which the tsunami reconstruction by the TEC inversion is less efficient due to the ionospheric noise background associated to geomagnetic storm, which occurred on the earthquake day, we show that the peak-to-peak amplitude of the sea level <span class="hlt">variation</span> inverted by this method can be compared to the tsunami <span class="hlt">wave</span> height measured by a DART buoy with an error of less than 20%. This demonstrates that the inversion of TEC data with a tsunami normal-mode summation approach is able to estimate quite <span class="hlt">accurately</span> the amplitude and waveform of the first tsunami arrival.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19740029285&hterms=falling+meteors&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dfalling%2Bmeteors','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19740029285&hterms=falling+meteors&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dfalling%2Bmeteors"><span>Upper atmospheric planetary-<span class="hlt">wave</span> and gravity-<span class="hlt">wave</span> observations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Justus, C. G.; Woodrum, A.</p> <p>1973-01-01</p> <p>Previously collected data on atmospheric pressure, density, temperature and winds between 25 and 200 km from sources including Meteorological Rocket Network data, ROBIN falling sphere data, grenade release and pitot tube data, meteor winds, chemical release winds, satellite data, and others were analyzed by a daily-difference method, and results on the magnitude of atmospheric perturbations interpreted as gravity <span class="hlt">waves</span> and planetary <span class="hlt">waves</span> are presented. Traveling planetary-<span class="hlt">wave</span> contributions in the 25-85 km range were found to have significant height and latitudinal <span class="hlt">variation</span>. It was found that observed gravity-<span class="hlt">wave</span> density perturbations and wind are related to one another in the manner predicted by gravity-<span class="hlt">wave</span> theory. It was determined that, on the average, gravity-<span class="hlt">wave</span> energy deposition or reflection occurs at all altitudes except the 55-75 km region of the mesosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110007015','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110007015"><span>Middle Atmosphere Dynamics with Gravity <span class="hlt">Wave</span> Interactions in the Numerical Spectral Model: Tides and Planetary <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mayr, Hans G.; Mengel, J. G.; Chan, K. L.; Huang, F. T.</p> <p>2010-01-01</p> <p>As Lindzen (1981) had shown, small-scale gravity <span class="hlt">waves</span> (GW) produce the observed reversals of the zonal-mean circulation and temperature <span class="hlt">variations</span> in the upper mesosphere. The <span class="hlt">waves</span> also play a major role in modulating and amplifying the diurnal tides (DT) (e.g., Waltersheid, 1981; Fritts and Vincent, 1987; Fritts, 1995a). We summarize here the modeling studies with the mechanistic numerical spectral model (NSM) with Doppler spread parameterization for GW (Hines, 1997a, b), which describes in the middle atmosphere: (a) migrating and non-migrating DT, (b) planetary <span class="hlt">waves</span> (PW), and (c) global-scale inertio gravity <span class="hlt">waves</span>. Numerical experiments are discussed that illuminate the influence of GW filtering and nonlinear interactions between DT, PW, and zonal mean <span class="hlt">variations</span>. Keywords: Theoretical modeling, Middle atmosphere dynamics, Gravity <span class="hlt">wave</span> interactions, Migrating and non-migrating tides, Planetary <span class="hlt">waves</span>, Global-scale inertio gravity <span class="hlt">waves</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMOS43A1394C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMOS43A1394C"><span>Usefulness of <span class="hlt">Wave</span> Data Assimilation to the <span class="hlt">WAVE</span> WATCH III Modeling System</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Choi, J. K.; Dykes, J. D.; Yaremchuk, M.; Wittmann, P.</p> <p>2017-12-01</p> <p>In-situ and remote-sensed <span class="hlt">wave</span> data are more abundant currently than in years past, with excellent accuracy at global scales. Forecast skill of the <span class="hlt">WAVE</span> WATCH III model is improved by assimilation of these measurements and they are also useful for model validation and calibration. It has been known that the impact of assimilation in wind-sea conditions is not large, but spectra that result in large swell with long term propagation are identified and assimilated, the improved accuracy of the initial conditions improve the long-term forecasts. The Navy's assimilation method started with the simple Optimal Interpolation (OI) method. Operationally, Fleet Numerical Meteorology and Oceanography Center uses the sequential 2DVar scheme, but a new approach has been tested based on an adjoint-free method to <span class="hlt">variational</span> assimilation in <span class="hlt">WAVE</span> WATCH III. We will present the status of <span class="hlt">wave</span> data assimilation into the <span class="hlt">WAVE</span> WATCH III numerical model and upcoming development of this new adjoint-free <span class="hlt">variational</span> approach.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMGC22B..02Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMGC22B..02Z"><span>A Machine LearningFramework to Forecast <span class="hlt">Wave</span> Conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Y.; James, S. C.; O'Donncha, F.</p> <p>2017-12-01</p> <p>Recently, significant effort has been undertaken to quantify and extract <span class="hlt">wave</span> energy because it is renewable, environmental friendly, abundant, and often close to population centers. However, a major challenge is the ability to <span class="hlt">accurately</span> and quickly predict energy production, especially across a 48-hour cycle. <span class="hlt">Accurate</span> forecasting of <span class="hlt">wave</span> conditions is a challenging undertaking that typically involves solving the spectral action-balance equation on a discretized grid with high spatial resolution. The nature of the computations typically demands high-performance computing infrastructure. Using a case-study site at Monterey Bay, California, a machine learning framework was trained to replicate numerically simulated <span class="hlt">wave</span> conditions at a fraction of the typical computational cost. Specifically, the physics-based Simulating <span class="hlt">WAves</span> Nearshore (SWAN) model, driven by measured <span class="hlt">wave</span> conditions, nowcast ocean currents, and wind data, was used to generate training data for machine learning algorithms. The model was run between April 1st, 2013 and May 31st, 2017 generating forecasts at three-hour intervals yielding 11,078 distinct model outputs. SWAN-generated fields of 3,104 <span class="hlt">wave</span> heights and a characteristic period could be replicated through simple matrix multiplications using the mapping matrices from machine learning algorithms. In fact, <span class="hlt">wave</span>-height RMSEs from the machine learning algorithms (9 cm) were less than those for the SWAN model-verification exercise where those simulations were compared to buoy <span class="hlt">wave</span> data within the model domain (>40 cm). The validated machine learning approach, which acts as an <span class="hlt">accurate</span> surrogate for the SWAN model, can now be used to perform real-time forecasts of <span class="hlt">wave</span> conditions for the next 48 hours using available forecasted boundary <span class="hlt">wave</span> conditions, ocean currents, and winds. This solution has obvious applications to <span class="hlt">wave</span>-energy generation as <span class="hlt">accurate</span> <span class="hlt">wave</span> conditions can be forecasted with over a three-order-of-magnitude reduction in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018A%26A...609A...6B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018A%26A...609A...6B"><span>The temporal behaviour of MHD <span class="hlt">waves</span> in a partially ionized prominence-like plasma: Effect of heating and cooling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ballester, J. L.; Carbonell, M.; Soler, R.; Terradas, J.</p> <p>2018-01-01</p> <p>Context. During heating or cooling processes in prominences, the plasma microscopic parameters are modified due to the change of temperature and ionization degree. Furthermore, if <span class="hlt">waves</span> are excited on this non-stationary plasma, the changing physical conditions of the plasma also affect <span class="hlt">wave</span> dynamics. Aims: Our aim is to study how temporal <span class="hlt">variation</span> of temperature and microscopic plasma parameters modify the behaviour of magnetohydrodynamic (MHD) <span class="hlt">waves</span> excited in a prominence-like hydrogen plasma. Methods: Assuming optically thin radiation, a constant external heating, the full expression of specific internal energy, and a suitable energy equation, we have derived the profiles for the temporal <span class="hlt">variation</span> of the background temperature. We have computed the <span class="hlt">variation</span> of the ionization degree using a Saha equation, and have linearized the single-fluid MHD equations to study the temporal behaviour of MHD <span class="hlt">waves</span>. Results: For all the MHD <span class="hlt">waves</span> considered, the period and damping time become time dependent. In the case of Alfvén <span class="hlt">waves</span>, the cut-off wavenumbers also become time dependent and the attenuation rate is completely different in a cooling or heating process. In the case of slow <span class="hlt">waves</span>, while it is difficult to distinguish the slow <span class="hlt">wave</span> properties in a cooling partially ionized plasma from those in an almost fully ionized plasma, the period and damping time of these <span class="hlt">waves</span> in both plasmas are completely different when the plasma is heated. The temporal behaviour of the Alfvén and fast <span class="hlt">wave</span> is very similar in the cooling case, but in the heating case, an important difference appears that is related with the time damping. Conclusions: Our results point out important differences in the behaviour of MHD <span class="hlt">waves</span> when the plasma is heated or cooled, and show that a correct interpretation of the observed prominence oscillations is very important in order to put <span class="hlt">accurate</span> constraints on the physical situation of the prominence plasma under study, that is, to perform prominence</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PMB....61.8135Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PMB....61.8135Z"><span>Robust dynamic myocardial perfusion CT deconvolution for <span class="hlt">accurate</span> residue function estimation via adaptive-weighted tensor total <span class="hlt">variation</span> regularization: a preclinical study</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zeng, Dong; Gong, Changfei; Bian, Zhaoying; Huang, Jing; Zhang, Xinyu; Zhang, Hua; Lu, Lijun; Niu, Shanzhou; Zhang, Zhang; Liang, Zhengrong; Feng, Qianjin; Chen, Wufan; Ma, Jianhua</p> <p>2016-11-01</p> <p>Dynamic myocardial perfusion computed tomography (MPCT) is a promising technique for quick diagnosis and risk stratification of coronary artery disease. However, one major drawback of dynamic MPCT imaging is the heavy radiation dose to patients due to its dynamic image acquisition protocol. In this work, to address this issue, we present a robust dynamic MPCT deconvolution algorithm via adaptive-weighted tensor total <span class="hlt">variation</span> (AwTTV) regularization for <span class="hlt">accurate</span> residue function estimation with low-mA s data acquisitions. For simplicity, the presented method is termed ‘MPD-AwTTV’. More specifically, the gains of the AwTTV regularization over the original tensor total <span class="hlt">variation</span> regularization are from the anisotropic edge property of the sequential MPCT images. To minimize the associative objective function we propose an efficient iterative optimization strategy with fast convergence rate in the framework of an iterative shrinkage/thresholding algorithm. We validate and evaluate the presented algorithm using both digital XCAT phantom and preclinical porcine data. The preliminary experimental results have demonstrated that the presented MPD-AwTTV deconvolution algorithm can achieve remarkable gains in noise-induced artifact suppression, edge detail preservation, and <span class="hlt">accurate</span> flow-scaled residue function and MPHM estimation as compared with the other existing deconvolution algorithms in digital phantom studies, and similar gains can be obtained in the porcine data experiment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015OcMod..92..115A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015OcMod..92..115A"><span>A hybrid genetic algorithm-extreme learning machine approach for <span class="hlt">accurate</span> significant <span class="hlt">wave</span> height reconstruction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Alexandre, E.; Cuadra, L.; Nieto-Borge, J. C.; Candil-García, G.; del Pino, M.; Salcedo-Sanz, S.</p> <p>2015-08-01</p> <p><span class="hlt">Wave</span> parameters computed from time series measured by buoys (significant <span class="hlt">wave</span> height Hs, mean <span class="hlt">wave</span> period, etc.) play a key role in coastal engineering and in the design and operation of <span class="hlt">wave</span> energy converters. Storms or navigation accidents can make measuring buoys break down, leading to missing data gaps. In this paper we tackle the problem of locally reconstructing Hs at out-of-operation buoys by using <span class="hlt">wave</span> parameters from nearby buoys, based on the spatial correlation among values at neighboring buoy locations. The novelty of our approach for its potential application to problems in coastal engineering is twofold. On one hand, we propose a genetic algorithm hybridized with an extreme learning machine that selects, among the available <span class="hlt">wave</span> parameters from the nearby buoys, a subset FnSP with nSP parameters that minimizes the Hs reconstruction error. On the other hand, we evaluate to what extent the selected parameters in subset FnSP are good enough in assisting other machine learning (ML) regressors (extreme learning machines, support vector machines and gaussian process regression) to reconstruct Hs. The results show that all the ML method explored achieve a good Hs reconstruction in the two different locations studied (Caribbean Sea and West Atlantic).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18709124','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18709124"><span>In situ <span class="hlt">accurate</span> determination of the zero time delay between two independent ultrashort laser pulses by observing the oscillation of an atomic excited <span class="hlt">wave</span> packet.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Qun; Hepburn, John W</p> <p>2008-08-15</p> <p>We propose a novel method that uses the oscillation of an atomic excited <span class="hlt">wave</span> packet observed through a pump-probe technique to <span class="hlt">accurately</span> determine the zero time delay between a pair of ultrashort laser pulses. This physically based approach provides an easy fix for the intractable problem of synchronizing two different femtosecond laser pulses in a practical experimental environment, especially where an in situ time zero measurement with high accuracy is required.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhRvA..97d2708J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhRvA..97d2708J"><span>s -<span class="hlt">wave</span> scattering length of a Gaussian potential</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jeszenszki, Peter; Cherny, Alexander Yu.; Brand, Joachim</p> <p>2018-04-01</p> <p>We provide <span class="hlt">accurate</span> expressions for the s -<span class="hlt">wave</span> scattering length for a Gaussian potential well in one, two, and three spatial dimensions. The Gaussian potential is widely used as a pseudopotential in the theoretical description of ultracold-atomic gases, where the s -<span class="hlt">wave</span> scattering length is a physically relevant parameter. We first describe a numerical procedure to compute the value of the s -<span class="hlt">wave</span> scattering length from the parameters of the Gaussian, but find that its accuracy is limited in the vicinity of singularities that result from the formation of new bound states. We then derive simple analytical expressions that capture the correct asymptotic behavior of the s -<span class="hlt">wave</span> scattering length near the bound states. Expressions that are increasingly <span class="hlt">accurate</span> in wide parameter regimes are found by a hierarchy of approximations that capture an increasing number of bound states. The small number of numerical coefficients that enter these expressions is determined from <span class="hlt">accurate</span> numerical calculations. The approximate formulas combine the advantages of the numerical and approximate expressions, yielding an <span class="hlt">accurate</span> and simple description from the weakly to the strongly interacting limit.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27768343','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27768343"><span>Enhanced Constraints for <span class="hlt">Accurate</span> Lower Bounds on Many-Electron Quantum Energies from <span class="hlt">Variational</span> Two-Electron Reduced Density Matrix Theory.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mazziotti, David A</p> <p>2016-10-07</p> <p>A central challenge of physics is the computation of strongly correlated quantum systems. The past ten years have witnessed the development and application of the <span class="hlt">variational</span> calculation of the two-electron reduced density matrix (2-RDM) without the <span class="hlt">wave</span> function. In this Letter we present an orders-of-magnitude improvement in the accuracy of 2-RDM calculations without an increase in their computational cost. The advance is based on a low-rank, dual formulation of an important constraint on the 2-RDM, the T2 condition. Calculations are presented for metallic chains and a cadmium-selenide dimer. The low-scaling T2 condition will have significant applications in atomic and molecular, condensed-matter, and nuclear physics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvL.117o3001M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvL.117o3001M"><span>Enhanced Constraints for <span class="hlt">Accurate</span> Lower Bounds on Many-Electron Quantum Energies from <span class="hlt">Variational</span> Two-Electron Reduced Density Matrix Theory</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mazziotti, David A.</p> <p>2016-10-01</p> <p>A central challenge of physics is the computation of strongly correlated quantum systems. The past ten years have witnessed the development and application of the <span class="hlt">variational</span> calculation of the two-electron reduced density matrix (2-RDM) without the <span class="hlt">wave</span> function. In this Letter we present an orders-of-magnitude improvement in the accuracy of 2-RDM calculations without an increase in their computational cost. The advance is based on a low-rank, dual formulation of an important constraint on the 2-RDM, the T 2 condition. Calculations are presented for metallic chains and a cadmium-selenide dimer. The low-scaling T 2 condition will have significant applications in atomic and molecular, condensed-matter, and nuclear physics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005PhFl...17h4108C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005PhFl...17h4108C"><span><span class="hlt">Waves</span> on radial film flows</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cholemari, Murali R.; Arakeri, Jaywant H.</p> <p>2005-08-01</p> <p>We study the stability of surface <span class="hlt">waves</span> on the radial film flow created by a vertical cylindrical water jet striking a horizontal plate. In such flows, surface <span class="hlt">waves</span> have been found to be unstable and can cause transition to turbulence. This surface-<span class="hlt">wave</span>-induced transition is different from the well-known Tollmien-Schlichting <span class="hlt">wave</span>-induced transition. The present study aims at understanding the instability and the transition process. We do a temporal stability analysis by assuming the flow to be locally two-dimensional but including spatial <span class="hlt">variations</span> to first order in the basic flow. The <span class="hlt">waves</span> are found to be dispersive, mostly unstable, and faster than the mean flow. Spatial <span class="hlt">variation</span> is the major destabilizing factor. Experiments are done to test the results of the linear stability analysis and to document the <span class="hlt">wave</span> breakup and transition. Comparison between theory and experiments is fairly good and indicates the adequacy of the model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA580663','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA580663"><span><span class="hlt">Wave</span> Current Interactions and <span class="hlt">Wave</span>-blocking Predictions Using NHWAVE Model</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2013-03-01</p> <p>Navier-Stokes equation. In this approach, as with previous modeling techniques, there is difficulty in simulating the free surface that inhibits <span class="hlt">accurate</span>...hydrostatic, free - surface , rotational flows in multiple dimensions. It is useful in predicting transformations of surface <span class="hlt">waves</span> and rapidly varied...Stelling, G., and M. Zijlema, 2003: An <span class="hlt">accurate</span> and efficient finite-differencing algorithm for non-hydrostatic free surface flow with application to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMDI13A2421N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMDI13A2421N"><span>Finite-Frequency Simulations of Core-Reflected Seismic <span class="hlt">Waves</span> to Assess Models of General Lower Mantle Anisotropy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nowacki, A.; Walker, A. M.; Wookey, J.; Kendall, J.</p> <p>2012-12-01</p> <p>The core-mantle boundary (CMB) region is the site of the largest change in properties in the Earth. Moreover, the lowermost mantle above it (known as D″) shows the largest lateral <span class="hlt">variations</span> in seismic velocity and strength of seismic anisotropy below the upper mantle. It is therefore vital to be able to <span class="hlt">accurately</span> forward model candidate structures in the lowermost mantle with realistic sensitivity to structure and at the same frequencies at which observations are made. We use the spectral finite-element method to produce synthetic seismograms of ScS <span class="hlt">waves</span> traversing a model of D″ anisotropy derived from mineralogical texture calculations and show that the seismic discontinuity atop the lowermost mantle varies in character laterally purely as a function of the strength and orientation of anisotropy. The lowermost mantle is widely anisotropic, shown by numerous shear <span class="hlt">wave</span> splitting studies using <span class="hlt">waves</span> of dominant frequency ~0.2-1 Hz. Whilst methods exist to model the finite-frequency seismic response of the lowermost mantle, most make the problem computationally efficient by imposing a certain symmetry to the problem, and of those which do not, almost none allow for completely general elasticity. Where low frequencies are simulated to reduce computational cost, it is uncertain whether <span class="hlt">waves</span> of that frequency have comparable sensitivity to D″ structure as those observed at shorter periods. Currently, therefore, these computational limitations precludes the ability to interpret our observations fully. We present recent developments in taking a general approach to forward-modelling <span class="hlt">waves</span> in D″. We use a modified version of SPECFEM3D_GLOBE, which uses the spectral finite-element method to model seismic <span class="hlt">wave</span> propagation in a fully generally-elastic (i.e., 3D-varying, arbitrarily anisotropic) Earth. The calculations are computationally challenging: to approach the frequency of the observations, up to 10,000 processor cores and up to 2 TB of memory are needed. The</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.S11D..04M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.S11D..04M"><span>The spatial sensitivity of Sp converted <span class="hlt">waves</span>-kernels and their applications</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mancinelli, N. J.; Fischer, K. M.</p> <p>2017-12-01</p> <p>We have developed a framework for improved imaging of strong lateral <span class="hlt">variations</span> in crust and upper mantle seismic discontinuity structure using teleseismic S-to-P (Sp) scattered <span class="hlt">waves</span>. In our framework, we rapidly compute scattered <span class="hlt">wave</span> sensitivities to velocity perturbations in a one-dimensional background model using ray-theoretical methods to account for timing, scattering, and geometrical spreading effects. The kernels <span class="hlt">accurately</span> describe the amplitude and phase information of a scattered waveform, which we confirm by benchmarking against kernels derived from numerical solutions of the <span class="hlt">wave</span> equation. The kernels demonstrate that the amplitude of an Sp converted <span class="hlt">wave</span> at a given time is sensitive to structure along a quasi-hyperbolic curve, such that structure far from the direct ray path can influence the measurements. We use synthetic datasets to explore two potential applications of the scattered <span class="hlt">wave</span> sensitivity kernels. First, we back-project scattered energy back to its origin using the kernel adjoint operator. This approach successfully images mantle interfaces at depths of 120-180 km with up to 20 km of vertical relief over lateral distances of 100 km (i.e., undulations with a maximal 20% grade) when station spacing is 10 km. Adjacent measurements sum coherently at nodes where gradients in seismic properties occur, and destructively interfere at nodes lacking gradients. In cases where the station spacing is greater than 10 km, the destructive interference can be incomplete, and smearing along the isochrons can occur. We demonstrate, however, that model smoothing can dampen these artifacts. This method is relatively fast, and <span class="hlt">accurately</span> retrieves the positions of the interfaces, but it generally does not retrieve the strength of the velocity perturbations. Therefore, in our second approach, we attempt to invert directly for velocity perturbations from our reference model using an iterative conjugate-directions scheme.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11837968','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11837968"><span>Acoustic propagation and atmosphere characteristics derived from infrasonic <span class="hlt">waves</span> generated by the Concorde.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Le, Pichon Alexis; Garcés, Milton; Blanc, Elisabeth; Barthélémy, Maud; Drob, Doug P</p> <p>2002-01-01</p> <p>Infrasonic signals generated by daily supersonic Concorde flights between North America and Europe have been consistently recorded by an array of microbarographs in France. These signals are used to investigate the effects of atmospheric variability on long-range sound propagation. Statistical analysis of <span class="hlt">wave</span> parameters shows seasonal and daily <span class="hlt">variations</span> associated with changes in the wind structure of the atmosphere. The measurements are compared to the predictions obtained by tracing rays through realistic atmospheric models. Theoretical ray paths allow a consistent interpretation of the observed <span class="hlt">wave</span> parameters. <span class="hlt">Variations</span> in the reflection level, travel time, azimuth deviation and propagation range are explained by the source and propagation models. The angular deviation of a ray's azimuth direction, due to the seasonal and diurnal fluctuations of the transverse wind component, is found to be approximately 5 degrees from the initial launch direction. One application of the seasonal and diurnal <span class="hlt">variations</span> of the observed phase parameters is the use of ground measurements to estimate fluctuations in the wind velocity at the reflection heights. The simulations point out that care must be taken when ascribing a phase velocity to a turning height. Ray path simulations which allow the correct computation of reflection heights are essential for <span class="hlt">accurate</span> phase identifications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhRvA..97b3601B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhRvA..97b3601B"><span>Matter-<span class="hlt">wave</span> diffraction approaching limits predicted by Feynman path integrals for multipath interference</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barnea, A. Ronny; Cheshnovsky, Ori; Even, Uzi</p> <p>2018-02-01</p> <p>Interference experiments have been paramount in our understanding of quantum mechanics and are frequently the basis of testing the superposition principle in the framework of quantum theory. In recent years, several studies have challenged the nature of <span class="hlt">wave</span>-function interference from the perspective of Born's rule—namely, the manifestation of so-called high-order interference terms in a superposition generated by diffraction of the <span class="hlt">wave</span> functions. Here we present an experimental test of multipath interference in the diffraction of metastable helium atoms, with large-number counting statistics, comparable to photon-based experiments. We use a <span class="hlt">variation</span> of the original triple-slit experiment and <span class="hlt">accurate</span> single-event counting techniques to provide a new experimental bound of 2.9 ×10-5 on the statistical deviation from the commonly approximated null third-order interference term in Born's rule for matter <span class="hlt">waves</span>. Our value is on the order of the maximal contribution predicted for multipath trajectories by Feynman path integrals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080004759','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080004759"><span>Tunnel effect <span class="hlt">wave</span> energy detection</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kaiser, William J. (Inventor); Waltman, Steven B. (Inventor); Kenny, Thomas W. (Inventor)</p> <p>1995-01-01</p> <p>Methods and apparatus for measuring gravitational and inertial forces, magnetic fields, or <span class="hlt">wave</span> or radiant energy acting on an object or fluid in space provide an electric tunneling current through a gap between an electrode and that object or fluid in space and vary that gap with any selected one of such forces, magnetic fields, or <span class="hlt">wave</span> or radiant energy acting on that object or fluid. These methods and apparatus sense a corresponding <span class="hlt">variation</span> in an electric property of that gap and determine the latter force, magnetic fields, or <span class="hlt">wave</span> or radiant energy in response to that corresponding <span class="hlt">variation</span>, and thereby sense or measure such parameters as acceleration, position, particle mass, velocity, magnetic field strength, presence or direction, or <span class="hlt">wave</span> or radiant energy intensity, presence or direction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730008777','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730008777"><span>Short and long periodic atmospheric <span class="hlt">variations</span> between 25 and 200 km</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Justus, C. G.; Woodrum, A.</p> <p>1973-01-01</p> <p>Previously collected data on atmospheric pressure, density, temperature and winds between 25 and 200 km from sources including Meteorological Rocket Network data, ROBIN falling sphere data, grenade release and pitot tube data, meteor winds, chemical release winds, satellite data, and others were analyzed by a daily difference method and results on the distribution statistics, magnitude, and spatial structure of gravity <span class="hlt">wave</span> and planetary <span class="hlt">wave</span> atmospheric <span class="hlt">variations</span> are presented. Time structure of the gravity <span class="hlt">wave</span> <span class="hlt">variations</span> were determined by the analysis of residuals from harmonic analysis of time series data. Planetary <span class="hlt">wave</span> contributions in the 25-85 km range were discovered and found to have significant height and latitudinal <span class="hlt">variation</span>. Long period planetary <span class="hlt">waves</span>, and seasonal <span class="hlt">variations</span> were also computed by harmonic analysis. Revised height <span class="hlt">variations</span> of the gravity <span class="hlt">wave</span> contributions in the 25 to 85 km height range were computed. An engineering method and design values for gravity <span class="hlt">wave</span> magnitudes and <span class="hlt">wave</span> lengths are given to be used for such tasks as evaluating the effects on the dynamical heating, stability and control of spacecraft such as the space shuttle vehicle in launch or reentry trajectories.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22583215','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22583215"><span>The role of axis embedding on rigid rotor decomposition analysis of <span class="hlt">variational</span> rovibrational <span class="hlt">wave</span> functions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Szidarovszky, Tamás; Fábri, Csaba; Császár, Attila G</p> <p>2012-05-07</p> <p>Approximate rotational characterization of <span class="hlt">variational</span> rovibrational <span class="hlt">wave</span> functions via the rigid rotor decomposition (RRD) protocol is developed for Hamiltonians based on arbitrary sets of internal coordinates and axis embeddings. An efficient and general procedure is given that allows employing the Eckart embedding with arbitrary polyatomic Hamiltonians through a fully numerical approach. RRD tables formed by projecting rotational-vibrational <span class="hlt">wave</span> functions into products of rigid-rotor basis functions and previously determined vibrational eigenstates yield rigid-rotor labels for rovibrational eigenstates by selecting the largest overlap. Embedding-dependent RRD analyses are performed, up to high energies and rotational excitations, for the H(2) (16)O isotopologue of the water molecule. Irrespective of the embedding chosen, the RRD procedure proves effective in providing unambiguous rotational assignments at low energies and J values. Rotational labeling of rovibrational states of H(2) (16)O proves to be increasingly difficult beyond about 10,000 cm(-1), close to the barrier to linearity of the water molecule. For medium energies and excitations the Eckart embedding yields the largest RRD coefficients, thus providing the largest number of unambiguous rotational labels.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1377063','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1377063"><span>Assimilation of <span class="hlt">Wave</span> Imaging Radar Observations for Real-time <span class="hlt">Wave-by-Wave</span> Forecasting</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Simpson, Alexandra; Haller, Merrick; Walker, David</p> <p></p> <p>This project addressed Topic 3: “<span class="hlt">Wave</span> Measurement Instrumentation for Feed Forward Controls” under the FOA number DE-FOA-0000971. The overall goal of the program was to develop a phase-resolving <span class="hlt">wave</span> forecasting technique for application to the active control of <span class="hlt">Wave</span> Energy Conversion (WEC) devices. We have developed an approach that couples a <span class="hlt">wave</span> imaging marine radar with a phase-resolving linear <span class="hlt">wave</span> model for real-time <span class="hlt">wave</span> field reconstruction and forward propagation of the <span class="hlt">wave</span> field in space and time. The scope of the project was to develop and assess the performance of this novel forecasting system. Specific project goals were as follows:more » Develop and verify a fast, GPU-based (Graphical Processing Unit) <span class="hlt">wave</span> propagation model suitable for phase-resolved computation of nearshore <span class="hlt">wave</span> transformation over variable bathymetry; Compare the accuracy and speed of performance of the <span class="hlt">wave</span> model against a deep water model in their ability to predict <span class="hlt">wave</span> field transformation in the intermediate water depths (50 to 70 m) typical of planned WEC sites; Develop and implement a <span class="hlt">variational</span> assimilation algorithm that can ingest <span class="hlt">wave</span> imaging radar observations and estimate the time-varying <span class="hlt">wave</span> conditions offshore of the domain of interest such that the observed <span class="hlt">wave</span> field is best reconstructed throughout the domain and then use this to produce model forecasts for a given WEC location; Collect <span class="hlt">wave</span>-resolving marine radar data, along with relevant in situ <span class="hlt">wave</span> data, at a suitable <span class="hlt">wave</span> energy test site, apply the algorithm to the field data, assess performance, and identify any necessary improvements; and Develop a production cost estimate that addresses the affordability of the <span class="hlt">wave</span> forecasting technology and include in the Final Report. The developed forecasting algorithm (“Wavecast”) was evaluated for both speed and accuracy against a substantial synthetic dataset. Early in the project, performance tests definitively demonstrated that the system was capable</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26833260','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26833260"><span>COSMOS: <span class="hlt">accurate</span> detection of somatic structural <span class="hlt">variations</span> through asymmetric comparison between tumor and normal samples.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yamagata, Koichi; Yamanishi, Ayako; Kokubu, Chikara; Takeda, Junji; Sese, Jun</p> <p>2016-05-05</p> <p>An important challenge in cancer genomics is precise detection of structural <span class="hlt">variations</span> (SVs) by high-throughput short-read sequencing, which is hampered by the high false discovery rates of existing analysis tools. Here, we propose an <span class="hlt">accurate</span> SV detection method named COSMOS, which compares the statistics of the mapped read pairs in tumor samples with isogenic normal control samples in a distinct asymmetric manner. COSMOS also prioritizes the candidate SVs using strand-specific read-depth information. Performance tests on modeled tumor genomes revealed that COSMOS outperformed existing methods in terms of F-measure. We also applied COSMOS to an experimental mouse cell-based model, in which SVs were induced by genome engineering and gamma-ray irradiation, followed by polymerase chain reaction-based confirmation. The precision of COSMOS was 84.5%, while the next best existing method was 70.4%. Moreover, the sensitivity of COSMOS was the highest, indicating that COSMOS has great potential for cancer genome analysis. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970003087','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970003087"><span>A <span class="hlt">Variational</span> Formulation for the Finite Element Analysis of Sound <span class="hlt">Wave</span> Propagation in a Spherical Shell</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lebiedzik, Catherine</p> <p>1995-01-01</p> <p>Development of design tools to furnish optimal acoustic environments for lightweight aircraft demands the ability to simulate the acoustic system on a workstation. In order to form an effective mathematical model of the phenomena at hand, we have begun by studying the propagation of acoustic <span class="hlt">waves</span> inside closed spherical shells. Using a fully-coupled fluid-structure interaction model based upon <span class="hlt">variational</span> principles, we have written a finite element analysis program and are in the process of examining several test cases. Future investigations are planned to increase model accuracy by incorporating non-linear and viscous effects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1409183-charge-transfer-excited-states-seeking-balanced-efficient-wave-function-ansatz-variational-monte-carlo','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1409183-charge-transfer-excited-states-seeking-balanced-efficient-wave-function-ansatz-variational-monte-carlo"><span>Charge-transfer excited states: Seeking a balanced and efficient <span class="hlt">wave</span> function ansatz in <span class="hlt">variational</span> Monte Carlo</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Blunt, Nick S.; Neuscamman, Eric</p> <p>2017-11-16</p> <p>We present a simple and efficient <span class="hlt">wave</span> function ansatz for the treatment of excited charge-transfer states in real-space quantum Monte Carlo methods. Using the recently-introduced <span class="hlt">variation</span>-after-response method, this ansatz allows a crucial orbital optimization step to be performed beyond a configuration interaction singles expansion, while only requiring calculation of two Slater determinant objects. As a result, we demonstrate this ansatz for the illustrative example of the stretched LiF molecule, for a range of excited states of formaldehyde, and finally for the more challenging ethylene-tetrafluoroethylene molecule.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JPS...384..342L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JPS...384..342L"><span>Estimating state of charge and health of lithium-ion batteries with guided <span class="hlt">waves</span> using built-in piezoelectric sensors/actuators</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ladpli, Purim; Kopsaftopoulos, Fotis; Chang, Fu-Kuo</p> <p>2018-04-01</p> <p>This work presents the feasibility of monitoring state of charge (SoC) and state of health (SoH) of lithium-ion pouch batteries with acousto-ultrasonic guided <span class="hlt">waves</span>. The guided <span class="hlt">waves</span> are propagated and sensed using low-profile, built-in piezoelectric disc transducers that can be retrofitted onto off-the-shelf batteries. Both experimental and analytical studies are performed to understand the relationship between guided <span class="hlt">waves</span> generated in a pitch-catch mode and battery SoC/SoH. The preliminary experiments on representative pouch cells show that the changes in time of flight (ToF) and signal amplitude (SA) resulting from shifts in the guided <span class="hlt">wave</span> signals correlate strongly with the electrochemical charge-discharge cycling and aging. An analytical acoustic model is developed to simulate the <span class="hlt">variations</span> in electrode moduli and densities during cycling, which correctly validates the absolute values and range of experimental ToF. It is further illustrated via a statistical study that ToF and SA can be used in a prediction model to <span class="hlt">accurately</span> estimate SoC/SoH. Additionally, by using multiple sensors in a network configuration on the same battery, a significantly more reliable and <span class="hlt">accurate</span> SoC/SoH prediction is achieved. The indicative results from this study can be extended to develop a unified guided-<span class="hlt">wave</span>-based framework for SoC/SoH monitoring of many lithium-ion battery applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018NIMPA.897...81X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018NIMPA.897...81X"><span>Study of <span class="hlt">wave</span> form compensation at CSNS/RCS magnets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xu, S. Y.; Fu, S. N.; Wang, S.; Kang, W.; Qi, X.; Li, L.; Deng, C. D.; Zhou, J. X.</p> <p>2018-07-01</p> <p>A method of <span class="hlt">wave</span> form compensation for magnets of the Rapid Cycling Synchrotron (RCS), which is based on transfer function between magnetic field and exciting current, was investigated on the magnets of RCS of Chinese Spallation Neutron Source (CSNS). By performing <span class="hlt">wave</span> form compensation, the magnetic field ramping function for RCS magnets can be <span class="hlt">accurately</span> controlled to the given <span class="hlt">wave</span> form, which is not limited to sine function. The method of <span class="hlt">wave</span> form compensation introduced in this paper can be used to reduce the magnetic field tracking errors, and can also be used to <span class="hlt">accurately</span> control the betatron tune for RCS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011aogs...27....1P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011aogs...27....1P"><span>Results of Computing Amplitude and Phase of the VLF <span class="hlt">Wave</span> Using <span class="hlt">Wave</span> Hop Theory</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pal, Sujay; Basak, Tamal; Chakrabarti, Sandip K.</p> <p>2011-07-01</p> <p>We present the basics of the <span class="hlt">wave</span> hop theory to compute the amplitude and phase of the VLF signals. We use the Indian Navy VTX transmitter at 18.2 kHz as an example of the source and compute the VLF propagation characteristics for several propagation paths using the <span class="hlt">wave</span>-hop theory. We find the signal amplitudes as a function of distance from the transmitter using <span class="hlt">wave</span> hop theory in different bearing angles and compare with the same obtained from the Long <span class="hlt">Wave</span> Propagation Capability (LWPC) code which uses the mode theory. We repeat a similar exercise for the diurnal and seasonal behavior. We note that the signal <span class="hlt">variation</span> by <span class="hlt">wave</span> hop theory gives more detailed information in the day time. We further present the spatial <span class="hlt">variation</span> of the signal amplitude over whole of India at a given time including the effect of sunrise and sunset terminator and also compare the same with that from the mode theory. We point out that the terminator effect is clearly understood in <span class="hlt">wave</span> hop results than that from the mode theory.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PMB....62.1149W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PMB....62.1149W"><span>An analysis of intrinsic <span class="hlt">variations</span> of low-frequency shear <span class="hlt">wave</span> speed in a stochastic tissue model: the first application for staging liver fibrosis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Yu; Wang, Min; Jiang, Jingfeng</p> <p>2017-02-01</p> <p>Shear <span class="hlt">wave</span> elastography is increasingly being used to non-invasively stage liver fibrosis by measuring shear <span class="hlt">wave</span> speed (SWS). This study quantitatively investigates intrinsic <span class="hlt">variations</span> among SWS measurements obtained from heterogeneous media such as fibrotic livers. More specifically, it aims to demonstrate that intrinsic <span class="hlt">variations</span> in SWS measurements, in general, follow a non-Gaussian distribution and are related to the heterogeneous nature of the medium being measured. Using the principle of maximum entropy (ME), our primary objective is to derive a probability density function (PDF) of the SWS distribution in conjunction with a lossless stochastic tissue model. Our secondary objective is to evaluate the performance of the proposed PDF using Monte Carlo (MC)-simulated shear <span class="hlt">wave</span> (SW) data against three other commonly used PDFs. Based on statistical evaluation criteria, initial results showed that the derived PDF fits better to MC-simulated SWS data than the other three PDFs. It was also found that SW fronts stabilized after a short (compared with the SW wavelength) travel distance in lossless media. Furthermore, in lossless media, the distance required to stabilize the SW propagation was not correlated to the SW wavelength at the low frequencies investigated (i.e. 50, 100 and 150 Hz). Examination of the MC simulation data suggests that elastic (shear) <span class="hlt">wave</span> scattering became more pronounced when the volume fraction of hard inclusions increased from 10 to 30%. In conclusion, using the principle of ME, we theoretically demonstrated for the first time that SWS measurements in this model follow a non-Gaussian distribution. Preliminary data indicated that the proposed PDF can quantitatively represent intrinsic <span class="hlt">variations</span> in SWS measurements simulated using a two-phase random medium model. The advantages of the proposed PDF are its physically meaningful parameters and solid theoretical basis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Freq...70..397G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Freq...70..397G"><span>An <span class="hlt">Accurate</span> Method for Measuring Airplane-Borne Conformal Antenna's Radar Cross Section</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guo, Shuxia; Zhang, Lei; Wang, Yafeng; Hu, Chufeng</p> <p>2016-09-01</p> <p>The airplane-borne conformal antenna attaches itself tightly with the airplane skin, so the conventional measurement method cannot determine the contribution of the airplane-borne conformal antenna to its radar cross section (RCS). This paper uses the 2D microwave imaging to isolate and extract the distribution of the reflectivity of the airplane-borne conformal antenna. It obtains the 2D spatial spectra of the conformal antenna through the <span class="hlt">wave</span> spectral transform between the 2D spatial image and the 2D spatial spectrum. After the interpolation from the rectangular coordinate domain to the polar coordinate domain, the spectral domain data for the <span class="hlt">variation</span> of the scatter of the conformal antenna with frequency and angle is obtained. The experimental results show that the measurement method proposed in this paper greatly enhances the airplane-borne conformal antenna's RCS measurement accuracy, essentially eliminates the influences caused by the airplane skin and more <span class="hlt">accurately</span> reveals the airplane-borne conformal antenna's RCS scatter properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26262620','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26262620"><span>Ocean <span class="hlt">Wave</span> Separation Using CEEMD-Wavelet in GPS <span class="hlt">Wave</span> Measurement.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Junjie; He, Xiufeng; Ferreira, Vagner G</p> <p>2015-08-07</p> <p>Monitoring ocean <span class="hlt">waves</span> plays a crucial role in, for example, coastal environmental and protection studies. Traditional methods for measuring ocean <span class="hlt">waves</span> are based on ultrasonic sensors and accelerometers. However, the Global Positioning System (GPS) has been introduced recently and has the advantage of being smaller, less expensive, and not requiring calibration in comparison with the traditional methods. Therefore, for <span class="hlt">accurately</span> measuring ocean <span class="hlt">waves</span> using GPS, further research on the separation of the <span class="hlt">wave</span> signals from the vertical GPS-mounted carrier displacements is still necessary. In order to contribute to this topic, we present a novel method that combines complementary ensemble empirical mode decomposition (CEEMD) with a wavelet threshold denoising model (i.e., CEEMD-Wavelet). This method seeks to extract <span class="hlt">wave</span> signals with less residual noise and without losing useful information. Compared with the <span class="hlt">wave</span> parameters derived from the moving average skill, high pass filter and <span class="hlt">wave</span> gauge, the results show that the accuracy of the <span class="hlt">wave</span> parameters for the proposed method was improved with errors of about 2 cm and 0.2 s for mean <span class="hlt">wave</span> height and mean period, respectively, verifying the validity of the proposed method.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4570377','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4570377"><span>Ocean <span class="hlt">Wave</span> Separation Using CEEMD-Wavelet in GPS <span class="hlt">Wave</span> Measurement</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wang, Junjie; He, Xiufeng; Ferreira, Vagner G.</p> <p>2015-01-01</p> <p>Monitoring ocean <span class="hlt">waves</span> plays a crucial role in, for example, coastal environmental and protection studies. Traditional methods for measuring ocean <span class="hlt">waves</span> are based on ultrasonic sensors and accelerometers. However, the Global Positioning System (GPS) has been introduced recently and has the advantage of being smaller, less expensive, and not requiring calibration in comparison with the traditional methods. Therefore, for <span class="hlt">accurately</span> measuring ocean <span class="hlt">waves</span> using GPS, further research on the separation of the <span class="hlt">wave</span> signals from the vertical GPS-mounted carrier displacements is still necessary. In order to contribute to this topic, we present a novel method that combines complementary ensemble empirical mode decomposition (CEEMD) with a wavelet threshold denoising model (i.e., CEEMD-Wavelet). This method seeks to extract <span class="hlt">wave</span> signals with less residual noise and without losing useful information. Compared with the <span class="hlt">wave</span> parameters derived from the moving average skill, high pass filter and <span class="hlt">wave</span> gauge, the results show that the accuracy of the <span class="hlt">wave</span> parameters for the proposed method was improved with errors of about 2 cm and 0.2 s for mean <span class="hlt">wave</span> height and mean period, respectively, verifying the validity of the proposed method. PMID:26262620</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.3737H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.3737H"><span>Observations and Simulations of the Impact of <span class="hlt">Wave</span>-Current Interaction on <span class="hlt">Wave</span> Direction in the Surf Zone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hopkins, Julia; Elgar, Steve; Raubenheimer, Britt</p> <p>2017-04-01</p> <p><span class="hlt">Accurately</span> characterizing the interaction of <span class="hlt">waves</span> and currents can improve predictions of <span class="hlt">wave</span> propagation and subsequent sediment transport in the nearshore. Along the southern shoreline of Martha's Vineyard, MA, <span class="hlt">waves</span> propagate across strong tidal currents as they shoal, providing an ideal environment for investigating <span class="hlt">wave</span>-current interaction. <span class="hlt">Wave</span> directions and mean currents observed for two 1-month-long periods in 7- and 2-m water depths along 11 km of the Martha's Vineyard shoreline have strong tidal modulations. <span class="hlt">Wave</span> directions shift by as much as 70 degrees over a tidal cycle in 7 m depth, and by as much as 25 degrees in 2 m depth. The magnitude of the tidal modulations in the <span class="hlt">wave</span> field decreases alongshore to the west, consistent with the observed decrease in tidal currents from 2.1 to 0.2 m/s. The observations are reproduced <span class="hlt">accurately</span> by a numerical model (SWAN and Deflt3D-FLOW) that simulates <span class="hlt">waves</span> and currents over the observed bathymetry. Model simulations with and without <span class="hlt">wave</span>-current interaction and tidal depth changes demonstrate that the observed tidal modulations of the <span class="hlt">wave</span> field primarily are caused by <span class="hlt">wave</span>-current interaction and not by tidal changes to water depths over the nearby complex shoals. Sediment transport estimates from simulated <span class="hlt">wave</span> conditions using a range of tidal currents and offshore <span class="hlt">wave</span> fields indicate that the modulation of the <span class="hlt">wave</span> field at Martha's Vineyard can impact the direction of <span class="hlt">wave</span>-induced alongshore sediment transport, sometimes driving transport opposing the direction of the offshore incident <span class="hlt">wave</span> field. As such, the observations and model simulations suggest the importance of <span class="hlt">wave</span>-current interaction to tidally averaged transport in mixed-energy <span class="hlt">wave</span>-and-current nearshore environments. Supported by ASD(R&E), NSF, NOAA (Sea Grant), and ONR.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/842296','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/842296"><span><span class="hlt">Variational</span> Monte Carlo study of pentaquark states</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Mark W. Paris</p> <p>2005-07-01</p> <p><span class="hlt">Accurate</span> numerical solution of the five-body Schrodinger equation is effected via <span class="hlt">variational</span> Monte Carlo. The spectrum is assumed to exhibit a narrow resonance with strangeness S=+1. A fully antisymmetrized and pair-correlated five-quark <span class="hlt">wave</span> function is obtained for the assumed non-relativistic Hamiltonian which has spin, isospin, and color dependent pair interactions and many-body confining terms which are fixed by the non-exotic spectra. Gauge field dynamics are modeled via flux tube exchange factors. The energy determined for the ground states with J=1/2 and negative (positive) parity is 2.22 GeV (2.50 GeV). A lower energy negative parity state is consistent with recent latticemore » results. The short-range structure of the state is analyzed via its diquark content.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890032217&hterms=gravitational+lensing&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dgravitational%2Blensing','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890032217&hterms=gravitational+lensing&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dgravitational%2Blensing"><span>Cosmological gravitational <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Linder, Eric V.</p> <p>1988-01-01</p> <p>A cosmological background of gravitational <span class="hlt">waves</span> would alter the propagation of radiation, inducing redshift fluctuations, apparent source position deflections, and luminosity <span class="hlt">variations</span>. By comparing these astrophysical effects with observations, it is possible to deduce upper limits on the energy density present in gravitational <span class="hlt">waves</span>. Emphasis is placed on microwave background anisotropy from the redshift deviations and galaxy clustering correlation functions from the angular deviations. Many of the gravitational <span class="hlt">wave</span> effects are shown to be generalizations of the gravitational lensing formalism.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050180832','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050180832"><span><span class="hlt">Wave</span> Rotor Research and Technology Development</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Welch, Gerard E.</p> <p>1998-01-01</p> <p><span class="hlt">Wave</span> rotor technology offers the potential to increase the performance of gas turbine engines significantly, within the constraints imposed by current material temperature limits. The <span class="hlt">wave</span> rotor research at the NASA Lewis Research Center is a three-element effort: 1) Development of design and analysis tools to <span class="hlt">accurately</span> predict the performance of <span class="hlt">wave</span> rotor components; 2) Experiments to characterize component performance; 3) System integration studies to evaluate the effect of <span class="hlt">wave</span> rotor topping on the gas turbine engine system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990042326&hterms=Inertia&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DInertia','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990042326&hterms=Inertia&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DInertia"><span>Spectra of Baroclinic Inertia-Gravity <span class="hlt">Wave</span> Turbulence</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Glazman, Roman E.</p> <p>1996-01-01</p> <p>Baroclinic inertia-gravity (IG) <span class="hlt">waves</span> form a persistent background of thermocline depth and sea surface height oscillations. They also contribute to the kinetic energy of horizontal motions in the subsurface layer. Measured by the ratio of water particle velocity to <span class="hlt">wave</span> phase speed, the <span class="hlt">wave</span> nonlinearity may be rather high. Given a continuous supply of energy from external sources, nonlinear <span class="hlt">wave-wave</span> interactions among IG <span class="hlt">waves</span> would result in inertial cascades of energy, momentum, and <span class="hlt">wave</span> action. Based on a recently developed theory of <span class="hlt">wave</span> turbulence in scale-dependent systems, these cascades are investigated and IG <span class="hlt">wave</span> spectra are derived for an arbitrary degree of <span class="hlt">wave</span> nonlinearity. Comparisons with satellite-altimetry-based spectra of surface height <span class="hlt">variations</span> and with energy spectra of horizontal velocity fluctuations show good agreement. The well-known spectral peak at the inertial frequency is thus explained as a result of the inverse cascade. Finally, we discuss a possibility of inferring the internal Rossby radius of deformation and other dynamical properties of the upper thermocline from the spectra of SSH (sea surface height) <span class="hlt">variations</span> based on altimeter measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.7091Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.7091Z"><span>Near Shore <span class="hlt">Wave</span> Modeling and applications to <span class="hlt">wave</span> energy estimation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zodiatis, G.; Galanis, G.; Hayes, D.; Nikolaidis, A.; Kalogeri, C.; Adam, A.; Kallos, G.; Georgiou, G.</p> <p>2012-04-01</p> <p>The estimation of the <span class="hlt">wave</span> energy potential at the European coastline is receiving increased attention the last years as a result of the adaptation of novel policies in the energy market, the concernsfor global warming and the nuclear energy security problems. Within this framework, numerical <span class="hlt">wave</span> modeling systems keep a primary role in the <span class="hlt">accurate</span> description of <span class="hlt">wave</span> climate and microclimate that is a prerequisite for any <span class="hlt">wave</span> energy assessment study. In the present work two of the most popular <span class="hlt">wave</span> models are used for the estimation of the <span class="hlt">wave</span> parameters at the coastline of Cyprus: The latest parallel version of the <span class="hlt">wave</span> model WAM (ECMWF version), which employs new parameterization of shallow water effects, and the SWAN model, classically used for near shore <span class="hlt">wave</span> simulations. The results obtained from the <span class="hlt">wave</span> models near shores are studied by an energy estimation point of view: The <span class="hlt">wave</span> parameters that mainly affect the energy temporal and spatial distribution, that is the significant <span class="hlt">wave</span> height and the mean <span class="hlt">wave</span> period, are statistically analyzed,focusing onpossible different aspects captured by the two models. Moreover, the <span class="hlt">wave</span> spectrum distribution prevailing in different areas are discussed contributing, in this way, to the <span class="hlt">wave</span> energy assessmentin the area. This work is a part of two European projects focusing on the estimation of the <span class="hlt">wave</span> energy distribution around Europe: The MARINA platform (http://www.marina-platform.info/ index.aspx) and the Ewave (http://www.oceanography.ucy.ac.cy/ewave/) projects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26420468','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26420468"><span><span class="hlt">Wave</span>-particle interaction in the Faraday <span class="hlt">waves</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Francois, N; Xia, H; Punzmann, H; Shats, M</p> <p>2015-10-01</p> <p><span class="hlt">Wave</span> motion in disordered Faraday <span class="hlt">waves</span> is analysed in terms of oscillons or quasi-particles. The motion of these oscillons is measured using particle tracking tools and it is compared with the motion of fluid particles on the water surface. Both the real floating particles and the oscillons, representing the collective fluid motion, show Brownian-type dispersion exhibiting ballistic and diffusive mean squared displacement at short and long times, respectively. While the floating particles motion has been previously explained in the context of two-dimensional turbulence driven by Faraday <span class="hlt">waves</span>, no theoretical description exists for the random walk type motion of oscillons. It is found that the r.m.s velocity ⟨μ̃(osc)⟩(rms) of oscillons is directly related to the turbulent r.m.s. velocity ⟨μ̃⟩(rms) of the fluid particles in a broad range of vertical accelerations. The measured ⟨μ̃(osc)⟩(rms) <span class="hlt">accurately</span> explains the broadening of the frequency spectra of the surface elevation observed in disordered Faraday <span class="hlt">waves</span>. These results suggest that 2D turbulence is the driving force behind both the randomization of the oscillons motion and the resulting broadening of the <span class="hlt">wave</span> frequency spectra. The coupling between <span class="hlt">wave</span> motion and hydrodynamic turbulence demonstrated here offers new perspectives for predicting complex fluid transport from the knowledge of <span class="hlt">wave</span> field spectra and vice versa.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27446747','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27446747"><span><span class="hlt">Accurate</span> Cross Sections for Microanalysis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rez, Peter</p> <p>2002-01-01</p> <p>To calculate the intensity of x-ray emission in electron beam microanalysis requires a knowledge of the energy distribution of the electrons in the solid, the energy <span class="hlt">variation</span> of the ionization cross section of the relevant subshell, the fraction of ionizations events producing x rays of interest and the absorption coefficient of the x rays on the path to the detector. The theoretical predictions and experimental data available for ionization cross sections are limited mainly to K shells of a few elements. Results of systematic plane <span class="hlt">wave</span> Born approximation calculations with exchange for K, L, and M shell ionization cross sections over the range of electron energies used in microanalysis are presented. Comparisons are made with experimental measurement for selected K shells and it is shown that the plane <span class="hlt">wave</span> theory is not appropriate for overvoltages less than 2.5 V.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018EPJD...72...52F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018EPJD...72...52F"><span>Highly <span class="hlt">accurate</span> bound state calculations of the two-center molecular ions by using the universal <span class="hlt">variational</span> expansion for three-body systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Frolov, Alexei M.</p> <p>2018-03-01</p> <p>The universal <span class="hlt">variational</span> expansion for the non-relativistic three-body systems is explicitly constructed. This universal expansion can be used to perform highly <span class="hlt">accurate</span> numerical computations of the bound state spectra in various three-body systems, including Coulomb three-body systems with arbitrary particle masses and electric charges. Our main interest is related to the adiabatic three-body systems which contain one bound electron and two heavy nuclei of hydrogen isotopes: the protium p, deuterium d and tritium t. We also consider the analogous (model) hydrogen ion ∞H2+ with the two infinitely heavy nuclei.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018GeoJI.213.1559P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018GeoJI.213.1559P"><span>Near-surface compressional and shear <span class="hlt">wave</span> speeds constrained by body-<span class="hlt">wave</span> polarization analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Park, Sunyoung; Ishii, Miaki</p> <p>2018-06-01</p> <p>A new technique to constrain near-surface seismic structure that relates body-<span class="hlt">wave</span> polarization direction to the <span class="hlt">wave</span> speed immediately beneath a seismic station is presented. The P-<span class="hlt">wave</span> polarization direction is only sensitive to shear <span class="hlt">wave</span> speed but not to compressional <span class="hlt">wave</span> speed, while the S-<span class="hlt">wave</span> polarization direction is sensitive to both <span class="hlt">wave</span> speeds. The technique is applied to data from the High-Sensitivity Seismograph Network in Japan, and the results show that the <span class="hlt">wave</span> speed estimates obtained from polarization analysis are compatible with those from borehole measurements. The lateral <span class="hlt">variations</span> in <span class="hlt">wave</span> speeds correlate with geological and physical features such as topography and volcanoes. The technique requires minimal computation resources, and can be used on any number of three-component teleseismic recordings, opening opportunities for non-invasive and inexpensive study of the shallowest (˜100 m) crustal structures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20060027797','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20060027797"><span>Time-<span class="hlt">Accurate</span>, Unstructured-Mesh Navier-Stokes Computations with the Space-Time CESE Method</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chang, Chau-Lyan</p> <p>2006-01-01</p> <p>Application of the newly emerged space-time conservation element solution element (CESE) method to compressible Navier-Stokes equations is studied. In contrast to Euler equations solvers, several issues such as boundary conditions, numerical dissipation, and grid stiffness warrant systematic investigations and validations. Non-reflecting boundary conditions applied at the truncated boundary are also investigated from the stand point of acoustic <span class="hlt">wave</span> propagation. Validations of the numerical solutions are performed by comparing with exact solutions for steady-state as well as time-<span class="hlt">accurate</span> viscous flow problems. The test cases cover a broad speed regime for problems ranging from acoustic <span class="hlt">wave</span> propagation to 3D hypersonic configurations. Model problems pertinent to hypersonic configurations demonstrate the effectiveness of the CESE method in treating flows with shocks, unsteady <span class="hlt">waves</span>, and separations. Good agreement with exact solutions suggests that the space-time CESE method provides a viable alternative for time-<span class="hlt">accurate</span> Navier-Stokes calculations of a broad range of problems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AIPC.1949w0004M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AIPC.1949w0004M"><span>Structural damage detection using deep learning of ultrasonic guided <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Melville, Joseph; Alguri, K. Supreet; Deemer, Chris; Harley, Joel B.</p> <p>2018-04-01</p> <p>Structural health monitoring using ultrasonic guided <span class="hlt">waves</span> relies on <span class="hlt">accurate</span> interpretation of guided <span class="hlt">wave</span> propagation to distinguish damage state indicators. However, traditional physics based models do not provide an <span class="hlt">accurate</span> representation, and classic data driven techniques, such as a support vector machine, are too simplistic to capture the complex nature of ultrasonic guide <span class="hlt">waves</span>. To address this challenge, this paper uses a deep learning interpretation of ultrasonic guided <span class="hlt">waves</span> to achieve fast, <span class="hlt">accurate</span>, and automated structural damaged detection. To achieve this, full wavefield scans of thin metal plates are used, half from the undamaged state and half from the damaged state. This data is used to train our deep network to predict the damage state of a plate with 99.98% accuracy given signals from just 10 spatial locations on the plate, as compared to that of a support vector machine (SVM), which achieved a 62% accuracy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JSV...400..317R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JSV...400..317R"><span>Investigation of the reconstruction accuracy of guided <span class="hlt">wave</span> tomography using full waveform inversion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rao, Jing; Ratassepp, Madis; Fan, Zheng</p> <p>2017-07-01</p> <p>Guided <span class="hlt">wave</span> tomography is a promising tool to <span class="hlt">accurately</span> determine the remaining wall thicknesses of corrosion damages, which are among the major concerns for many industries. Full Waveform Inversion (FWI) algorithm is an attractive guided <span class="hlt">wave</span> tomography method, which uses a numerical forward model to predict the waveform of guided <span class="hlt">waves</span> when propagating through corrosion defects, and an inverse model to reconstruct the thickness map from the ultrasonic signals captured by transducers around the defect. This paper discusses the reconstruction accuracy of the FWI algorithm on plate-like structures by using simulations as well as experiments. It was shown that this algorithm can obtain a resolution of around 0.7 wavelengths for defects with smooth depth <span class="hlt">variations</span> from the acoustic modeling data, and about 1.5-2 wavelengths from the elastic modeling data. Further analysis showed that the reconstruction accuracy is also dependent on the shape of the defect. It was demonstrated that the algorithm maintains the accuracy in the case of multiple defects compared to conventional algorithms based on Born approximation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DFDR31008S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DFDR31008S"><span>Measurements of wind-<span class="hlt">waves</span> under transient wind conditions.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shemer, Lev; Zavadsky, Andrey</p> <p>2015-11-01</p> <p>Wind forcing in nature is always unsteady, resulting in a complicated evolution pattern that involves numerous time and space scales. In the present work, wind <span class="hlt">waves</span> in a laboratory wind-<span class="hlt">wave</span> flume are studied under unsteady forcing`. The <span class="hlt">variation</span> of the surface elevation is measured by capacitance <span class="hlt">wave</span> gauges, while the components of the instantaneous surface slope in across-wind and along-wind directions are determined by a regular or scanning laser slope gauge. The locations of the <span class="hlt">wave</span> gauge and of the laser slope gauge are separated by few centimeters in across-wind direction. Instantaneous wind velocity was recorded simultaneously using Pitot tube. Measurements are performed at a number of fetches and for different patterns of wind velocity <span class="hlt">variation</span>. For each case, at least 100 independent realizations were recorded for a given wind velocity <span class="hlt">variation</span> pattern. The accumulated data sets allow calculating ensemble-averaged values of the measured parameters. Significant differences between the evolution patterns of the surface elevation and of the slope components were found. Wavelet analysis was applied to determine dominant <span class="hlt">wave</span> frequency of the surface elevation and of the slope <span class="hlt">variation</span> at each instant. Corresponding ensemble-averaged values acquired by different sensors were computed and compared. Analysis of the measured ensemble-averaged quantities at different fetches makes it possible to identify different stages in the wind-<span class="hlt">wave</span> evolution and to estimate the appropriate time and length scales.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MolPh.116.1827D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MolPh.116.1827D"><span>Ground-state calculations of confined hydrogen molecule H2 using <span class="hlt">variational</span> Monte Carlo method</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Doma, S. B.; El-Gammal, F. N.; Amer, A. A.</p> <p>2018-07-01</p> <p>The <span class="hlt">variational</span> Monte Carlo method is used to evaluate the ground-state energy of a confined hydrogen molecule H2. Accordingly, we considered the.me case of hydrogen molecule confined by a hard prolate spheroidal cavity when the nuclear positions are clamped at the foci (on-focus case). Also, the case of off-focus nuclei in which the two nuclei are not clamped to the foci is studied. This case provides flexibility for the treatment of the molecular properties by selecting an arbitrary size and shape for the confining spheroidal box. A simple chemical analysis concerning the catalytic role of enzyme is investigated. An <span class="hlt">accurate</span> trial <span class="hlt">wave</span> function depending on many <span class="hlt">variational</span> parameters is used for this purpose. The obtained results for the case of clamped foci exhibit good accuracy compared with the high precision <span class="hlt">variational</span> data presented previously. In the case of off-focus nuclei, an improvement is obtained with respect to the most recent uncorrelated results existing in the literature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFMOS21D..07G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFMOS21D..07G"><span>HB06 : Field Validation of Realtime Predictions of Surfzone <span class="hlt">Waves</span> and Currents</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guza, R. T.; O'Reilly, W. C.; Feddersen, F.</p> <p>2006-12-01</p> <p>California shorelines can be contaminated by the discharge of polluted streams and rivers onto the beach face or into the surf zone. Management decisions (for example, beach closures) can be assisted by <span class="hlt">accurate</span> characterization of the <span class="hlt">waves</span> and currents that transport and mix these pollutants. A real-time, operational <span class="hlt">waves</span> and alongshore current model, developed for a 5 km alongshore reach at Huntington Beach (http://cdip.ucsd.edu/hb06/), will be tested for a month during Fall 2006 as part of the HB06 field experiment. The model has two components: prediction of incident <span class="hlt">waves</span> immediately seaward of the surf zone, and the transformation of breaking <span class="hlt">waves</span> across the surf zone. The California Safe Boating Network Model (O'Reilly et al., California World Ocean Conference, 2006) is used to estimate incident <span class="hlt">wave</span> properties. This regional <span class="hlt">wave</span> model accounts for blocking and refraction by offshore islands and shoals, and <span class="hlt">variation</span> of the shoreline orientation. At Huntington Beach, the network model uses four buoys exposed to the deep ocean to estimate swell, and four nearby buoys to estimate locally generated seas. The model predictions will be compared with directional <span class="hlt">wave</span> buoy observations in 22 m depth, 1 km from the shore. The computationally fast model for surfzone <span class="hlt">waves</span> and breaking-<span class="hlt">wave</span> driven alongshore currents, appropriate for random <span class="hlt">waves</span> on beaches with simple bathymetry, is based on concepts developed and tested by Ed Thornton and his colleagues over the last 30 years. Modeled alongshore currents at Huntington Beach, with incident <span class="hlt">waves</span> predicted by the Network model, will be compared with <span class="hlt">waves</span> and currents observed during HB06 along a transect extending from 4 m depth to the shoreline. Support from the California Coastal Conservancy, NOAA, and ONR is gratefully acknowledged.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMNH21C1827G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMNH21C1827G"><span>Diffraction and Dissipation of Atmospheric <span class="hlt">Waves</span> in the Vicinity of Caustics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Godin, O. A.</p> <p>2015-12-01</p> <p>A large and increasing number of ground-based and satellite-borne instruments has been demonstrated to reliably reveal ionospheric manifestations of natural hazards such as large earthquakes, strong tsunamis, and powerful tornadoes. To transition from detection of ionospheric manifestations of natural hazards to characterization of the hazards for the purposes of improving early warning systems and contributing to disaster recovery, it is necessary to relate quantitatively characteristics of the observed ionospheric disturbances and the underlying natural hazard and, in particular, <span class="hlt">accurately</span> model propagation of atmospheric <span class="hlt">waves</span> from the ground or ocean surface to the ionosphere. The ray theory has been used extensively to model propagation of atmospheric <span class="hlt">waves</span> and proved to be very efficient in elucidating the effects of atmospheric variability on ionospheric signatures of natural hazards. However, the ray theory predicts unphysical, divergent values of the <span class="hlt">wave</span> amplitude and needs to be modified in the vicinity of caustics. This paper presents an asymptotic theory that describes diffraction, focusing and increased dissipation of acoustic-gravity <span class="hlt">waves</span> in the vicinity of caustics and turning points. Air temperature, viscosity, thermal conductivity, and wind velocity are assumed to vary gradually with height and horizontal coordinates, and slowness of these <span class="hlt">variations</span> determines the large parameter of the problem. Uniform asymptotics of the <span class="hlt">wave</span> field are expressed in terms of Airy functions and their derivatives. The geometrical, or Berry, phase, which arises in the consistent WKB approximation for acoustic-gravity <span class="hlt">waves</span>, plays an important role in the caustic asymptotics. In addition to the <span class="hlt">wave</span> field in the vicinity of the caustic, these asymptotics describe <span class="hlt">wave</span> reflection from the caustic and the evanescent <span class="hlt">wave</span> field beyond the caustic. The evanescent <span class="hlt">wave</span> field is found to play an important role in ionospheric manifestations of tsunamis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4170828','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4170828"><span>Experimental and Numerical Studies on <span class="hlt">Wave</span> Breaking Characteristics over a Fringing Reef under Monochromatic <span class="hlt">Wave</span> Conditions</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2014-01-01</p> <p>Fringing reefs play an important role in protecting the coastal area by inducing <span class="hlt">wave</span> breaking and <span class="hlt">wave</span> energy dissipation. However, modeling of <span class="hlt">wave</span> transformation and energy dissipation on this topography is still difficult due to the unique structure. In the present study, two-dimensional laboratory experiments were conducted to investigate the cross-shore <span class="hlt">variations</span> of <span class="hlt">wave</span> transformation, setup, and breaking phenomena over an idealized fringing reef with the 1/40 reef slope and to verify the Boussinesq model under monochromatic <span class="hlt">wave</span> conditions. One-layer and two-layer model configurations of the Boussinesq model were used to figure out the model capability. Both models predicted well (r 2 > 0.8) the cross-shore <span class="hlt">variation</span> of the <span class="hlt">wave</span> heights, crests, troughs, and setups when the nonlinearity is not too high (A 0/h 0 < 0.07 in this study). However, as the <span class="hlt">wave</span> nonlinearity and steepness increase, the one-layer model showed problems in prediction and stability due to the error on the vertical profile of fluid velocity. The results in this study revealed that one-layer model is not suitable in the highly nonlinear <span class="hlt">wave</span> condition over a fringing reef bathymetry. This data set can contribute to the numerical model verification. PMID:25276853</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25276853','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25276853"><span>Experimental and numerical studies on <span class="hlt">wave</span> breaking characteristics over a fringing reef under monochromatic <span class="hlt">wave</span> conditions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lee, Jong-In; Shin, Sungwon; Kim, Young-Taek</p> <p>2014-01-01</p> <p>Fringing reefs play an important role in protecting the coastal area by inducing <span class="hlt">wave</span> breaking and <span class="hlt">wave</span> energy dissipation. However, modeling of <span class="hlt">wave</span> transformation and energy dissipation on this topography is still difficult due to the unique structure. In the present study, two-dimensional laboratory experiments were conducted to investigate the cross-shore <span class="hlt">variations</span> of <span class="hlt">wave</span> transformation, setup, and breaking phenomena over an idealized fringing reef with the 1/40 reef slope and to verify the Boussinesq model under monochromatic <span class="hlt">wave</span> conditions. One-layer and two-layer model configurations of the Boussinesq model were used to figure out the model capability. Both models predicted well (r (2) > 0.8) the cross-shore <span class="hlt">variation</span> of the <span class="hlt">wave</span> heights, crests, troughs, and setups when the nonlinearity is not too high (A 0/h 0 < 0.07 in this study). However, as the <span class="hlt">wave</span> nonlinearity and steepness increase, the one-layer model showed problems in prediction and stability due to the error on the vertical profile of fluid velocity. The results in this study revealed that one-layer model is not suitable in the highly nonlinear <span class="hlt">wave</span> condition over a fringing reef bathymetry. This data set can contribute to the numerical model verification.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19776785','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19776785"><span><span class="hlt">Accurate</span> numerical solution of the Helmholtz equation by iterative Lanczos reduction.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ratowsky, R P; Fleck, J A</p> <p>1991-06-01</p> <p>The Lanczos recursion algorithm is used to determine forward-propagating solutions for both the paraxial and Helmholtz <span class="hlt">wave</span> equations for longitudinally invariant refractive indices. By eigenvalue analysis it is demonstrated that the method gives extremely <span class="hlt">accurate</span> solutions to both equations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001APS..DFD.DE010W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001APS..DFD.DE010W"><span>A Semi-implicit Method for Time <span class="hlt">Accurate</span> Simulation of Compressible Flow</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wall, Clifton; Pierce, Charles D.; Moin, Parviz</p> <p>2001-11-01</p> <p>A semi-implicit method for time <span class="hlt">accurate</span> simulation of compressible flow is presented. The method avoids the acoustic CFL limitation, allowing a time step restricted only by the convective velocity. Centered discretization in both time and space allows the method to achieve zero artificial attenuation of acoustic <span class="hlt">waves</span>. The method is an extension of the standard low Mach number pressure correction method to the compressible Navier-Stokes equations, and the main feature of the method is the solution of a Helmholtz type pressure correction equation similar to that of Demirdžić et al. (Int. J. Num. Meth. Fluids, Vol. 16, pp. 1029-1050, 1993). The method is attractive for simulation of acoustic combustion instabilities in practical combustors. In these flows, the Mach number is low; therefore the time step allowed by the convective CFL limitation is significantly larger than that allowed by the acoustic CFL limitation, resulting in significant efficiency gains. Also, the method's property of zero artificial attenuation of acoustic <span class="hlt">waves</span> is important for <span class="hlt">accurate</span> simulation of the interaction between acoustic <span class="hlt">waves</span> and the combustion process. The method has been implemented in a large eddy simulation code, and results from several test cases will be presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015OptLT..75...16L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015OptLT..75...16L"><span>Simulation study and guidelines to generate Laser-induced Surface Acoustic <span class="hlt">Waves</span> for human skin feature detection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Tingting; Fu, Xing; Chen, Kun; Dorantes-Gonzalez, Dante J.; Li, Yanning; Wu, Sen; Hu, Xiaotang</p> <p>2015-12-01</p> <p>Despite the seriously increasing number of people contracting skin cancer every year, limited attention has been given to the investigation of human skin tissues. To this regard, Laser-induced Surface Acoustic <span class="hlt">Wave</span> (LSAW) technology, with its <span class="hlt">accurate</span>, non-invasive and rapid testing characteristics, has recently shown promising results in biological and biomedical tissues. In order to improve the measurement accuracy and efficiency of detecting important features in highly opaque and soft surfaces such as human skin, this paper identifies the most important parameters of a pulse laser source, as well as provides practical guidelines to recommended proper ranges to generate Surface Acoustic <span class="hlt">Waves</span> (SAWs) for characterization purposes. Considering that melanoma is a serious type of skin cancer, we conducted a finite element simulation-based research on the generation and propagation of surface <span class="hlt">waves</span> in human skin containing a melanoma-like feature, determine best pulse laser parameter ranges of <span class="hlt">variation</span>, simulation mesh size and time step, working bandwidth, and minimal size of detectable melanoma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.1833K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.1833K"><span>Full <span class="hlt">wave</span> description of VLF <span class="hlt">wave</span> penetration through the ionosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kuzichev, Ilya; Shklyar, David</p> <p>2010-05-01</p> <p>Of the many problems in whistler study, <span class="hlt">wave</span> propagation through the ionosphere is among the most important, and the most difficult at the same time. Both satellite and ground-based investigations of VLF <span class="hlt">waves</span> include considerations of this problem, and it has been in the focus of research since the beginning of whistler study (Budden [1985]; Helliwell [1965]). The difficulty in considering VLF <span class="hlt">wave</span> passage through the ionosphere is, after all, due to fast <span class="hlt">variation</span> of the lower ionosphere parameters as compared to typical VLF <span class="hlt">wave</span> number. This makes irrelevant the consideration in the framework of geometrical optics, which, along with a smooth <span class="hlt">variations</span> of parameters, is always based on a particular dispersion relation. Although the full <span class="hlt">wave</span> analysis in the framework of cold plasma approximation does not require slow <span class="hlt">variations</span> of plasma parameters, and does not assume any particular <span class="hlt">wave</span> mode, the fact that the <span class="hlt">wave</span> of a given frequency belongs to different modes in various regions makes numerical solution of the field equations not simple. More specifically, as is well known (e.g. Ginzburg and Rukhadze [1972]), in a cold magnetized plasma, there are, in general, two <span class="hlt">wave</span> modes related to a given frequency. Both modes, however, do not necessarily correspond to propagating <span class="hlt">waves</span>. In particular, in the frequency range related to whistler <span class="hlt">waves</span>, the other mode is evanescent, i.e. it has a negative value of N2 (the refractive index squared). It means that one of solutions of the relevant differential equations is exponentially growing, which makes a straightforward numerical approach to these equations despairing. This well known difficulty in the problem under discussion is usually identified as numerical swamping (Budden [1985]). Resolving the problem of numerical swamping becomes, in fact, a key point in numerical study of <span class="hlt">wave</span> passage through the ionosphere. As it is typical of work based on numerical simulations, its essential part remains virtually hidden</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.P33B0241F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.P33B0241F"><span>Density <span class="hlt">Waves</span> in Saturn's Rings from Cassini Radio Occultations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>French, R. G.; Rappaport, N. J.; Marouf, E. A.; McGhee, C. A.</p> <p>2005-12-01</p> <p>The Cassini Radio Science Team conducted a set of optimized diametric occultations by Saturn and its rings from May to September 2005, providing 11 separate probes of Saturn's ionosphere and atmosphere, and 12 optical depth profiles of the complete ring system. Each event was observed by the stations of the Deep Space Net (DSN) at three radio frequencies (S, X, Ka bands, with corresponding wavelengths of ? = 13, 3.6, and 0.9 cm). Very <span class="hlt">accurate</span> pointing by the spacecraft and ground antennas resulted in stable baseline signal levels, and the relatively large ring opening angle (B=19-25°) permitted us to probe even quite dense ring regions with excellent SNR. The RSS occultation technique enables us to recover very fine detailed radial structure by correcting for diffraction effects. Multiple occultation chords, covering a variety of ring longitudes and ring opening angles, reveal the structure of the rings in remarkable detail, including density and bending <span class="hlt">waves</span>, satellite wakes, and subtle <span class="hlt">variations</span> at the 100-m radius scale. Janus and Epimetheus are responsible for a particularly rich set of density <span class="hlt">waves</span>, and their coorbital interactions result in a complex interplay of time-variable ring structure over the 8-year libration period of the two satellites. We compare the first-order 2:1, 4:3, 5:4, and 6:5 coorbital density <span class="hlt">waves</span> from multiple occultation chords to linear density <span class="hlt">wave</span> models based on a dynamical model of the orbital exchange between the moons. From the observed dispersion relation of the <span class="hlt">wave</span> crests, we infer the surface mass density and eccentricity gradient of particle streamlines, and match the detailed shapes of the <span class="hlt">wave</span> crests using a non-linear analysis. Second-order coorbital features are also evident, and there are even hints of third-order density <span class="hlt">waves</span> in the high SNR radio occultation data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/sir/2013/5141/pdf/SIR13-5141.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/sir/2013/5141/pdf/SIR13-5141.pdf"><span>Shear <span class="hlt">wave</span> velocities of unconsolidated shallow sediments in the Gulf of Mexico</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Lee, Myung W.</p> <p>2013-01-01</p> <p><span class="hlt">Accurate</span> shear-<span class="hlt">wave</span> velocities for shallow sediments are important for a variety of seismic applications such as inver-sion and amplitude versus offset analysis. During the U.S. Department of Energy-sponsored Gas Hydrate Joint Industry Project Leg II, shear-<span class="hlt">wave</span> velocities were measured at six wells in the Gulf of Mexico using the logging-while-drilling SonicScope acoustic tool. Because the tool measurement point was only 35 feet from the drill bit, the adverse effect of the borehole condition, which is severe for the shallow unconsolidated sediments in the Gulf of Mexico, was mini-mized and <span class="hlt">accurate</span> shear-<span class="hlt">wave</span> velocities of unconsolidated sediments were measured. Measured shear-<span class="hlt">wave</span> velocities were compared with the shear-<span class="hlt">wave</span> velocities predicted from the compressional-<span class="hlt">wave</span> velocities using empirical formulas and the rock physics models based on the Biot-Gassmann theory, and the effectiveness of the two prediction methods was evaluated. Although the empirical equation derived from measured shear-<span class="hlt">wave</span> data is <span class="hlt">accurate</span> for predicting shear-<span class="hlt">wave</span> velocities for depths greater than 500 feet in these wells, the three-phase Biot-Gassmann-theory -based theory appears to be optimum for predicting shear-<span class="hlt">wave</span> velocities for shallow unconsolidated sediments in the Gulf of Mexico.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSA24A..04B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSA24A..04B"><span>Annual <span class="hlt">variation</span> of gravity-<span class="hlt">wave</span> activity at middle and high latitudes in a high-resolution GCM</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Becker, E.</p> <p>2017-12-01</p> <p>A high-resolution version of the Kuehlungsborn Mechanistic general Circulation Model (KMCM) with resolved gravity <span class="hlt">waves</span> (GWs) is employed to analyze the annual <span class="hlt">variation</span> of GW activity in both hemispheres at middle and high latitudes. The geographical distributions of GW hotspots in the winter stratosphere are consistent with existing satellite data. Vertical profiles up to the lower thermosphere agree with ground-based measurements for both season. The model confirms the semi-annual <span class="hlt">variation</span> of GW energy in the upper mesosphere that was found previously in radar-measurements in the northern hemisphere Furthermore, the GW potential energy per unit mass during winter shows two maxima, one around 50-70 km and one around 80-100 km. We interpret the upper maximum as a result of secondary GWs that are generated in the stratopause region due to the intermittent body forces of primary GWs. In a recent study we showed that these secondary GWs produce a significant eastward drag in the mesopause region during austral winter. This mechanism is found to be important in the northern winter as well.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFMNS41A1110K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFMNS41A1110K"><span>New Hybridized Surface <span class="hlt">Wave</span> Approach for Geotechnical Modeling of Shear <span class="hlt">Wave</span> Velocity at Strong Motion Recording Stations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kayen, R.; Carkin, B.; Minasian, D.</p> <p>2006-12-01</p> <p>Strong motion recording (SMR) networks often have little or no shear <span class="hlt">wave</span> velocity measurements at stations where characterization of site amplification and site period effects is needed. Using the active Spectral Analysis of Surface <span class="hlt">Waves</span> (SASW) method, and passive H/V microtremor method we have investigated nearly two hundred SMR sites in California, Alaska, Japan, Australia, China and Taiwan. We are conducting these studies, in part, to develop a new hybridized method of site characterization that utilizes a parallel array of harmonic-<span class="hlt">wave</span> sources for active-source SASW, and a single long period seismometer for passive-source microtremor measurement. Surface <span class="hlt">wave</span> methods excel in their ability to non-invasively and rapidly characterize the <span class="hlt">variation</span> of ground stiffness properties with depth below the surface. These methods are lightweight, inexpensive to deploy, and time-efficient. They have been shown to produce <span class="hlt">accurate</span> and deep soil stiffness profiles. By placing and wiring shakers in a large parallel circuit, either side-by-side on the ground or in a trailer-mounted array, a strong in-phase harmonic <span class="hlt">wave</span> can be produced. The effect of arraying many sources in parallel is to increase the amplitude of <span class="hlt">waves</span> received at far-away spaced seismometers at low frequencies so as to extend the longest wavelengths of the captured dispersion curve. The USGS system for profiling uses this concept by arraying between two and eight electro-mechanical harmonic-<span class="hlt">wave</span> shakers. With large parallel arrays of vibrators, a dynamic force in excess of 1000 lb can be produced to vibrate the ground and produce surface <span class="hlt">waves</span>. We adjust the harmonic <span class="hlt">wave</span> through a swept-sine procedure to profile surface <span class="hlt">wave</span> dispersion down to a frequency of 1 Hz and out to surface <span class="hlt">wave</span>-wavelengths of 200-1000 meters, depending on the site stiffness. The parallel-array SASW procedure is augmented using H/V microtremor data collected with the active source turned off. Passive array microtremor data</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730023377','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730023377"><span>Electromagnetic <span class="hlt">wave</span> energy converter</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bailey, R. L. (Inventor)</p> <p>1973-01-01</p> <p>Electromagnetic <span class="hlt">wave</span> energy is converted into electric power with an array of mutually insulated electromagnetic <span class="hlt">wave</span> absorber elements each responsive to an electric field component of the <span class="hlt">wave</span> as it impinges thereon. Each element includes a portion tapered in the direction of <span class="hlt">wave</span> propagation to provide a relatively wideband response spectrum. Each element includes an output for deriving a voltage replica of the electric field <span class="hlt">variations</span> intercepted by it. Adjacent elements are positioned relative to each other so that an electric field subsists between adjacent elements in response to the impinging <span class="hlt">wave</span>. The electric field results in a voltage difference between adjacent elements that is fed to a rectifier to derive dc output power.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.5096H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.5096H"><span>Annual and inter-annual <span class="hlt">variations</span> of 6.5-day-planetary-<span class="hlt">waves</span> in MLT observed by TIMED/SABER</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huang, Yingying; Li, Huijun; Li, Chongyin; Zhang, Shaodong</p> <p>2017-04-01</p> <p>Annual and inter-annual <span class="hlt">variations</span> of 6.5DWs in 20-110 km, 52°S-52°N, 2002-2016 are studied by using v2.0 TIMED/SABER kinetic temperature data. Firstly, global annual <span class="hlt">variations</span> of 6.5DW's spectral power and amplitudes are obtained. Strong <span class="hlt">wave</span> amplitudes emerge in 30°S/N-50°S/N, and peaks in altitude separate in stratosphere (40-50 km), mesosphere (80-90 km) and the lower thermosphere (100-110 km), respectively. Their annual <span class="hlt">variations</span> are similar in both hemispheres, but different in altitude. In 40-50 km, the annual maximums emerge mostly in winters: Dec.-Jan. in the NH and Jul.-Aug. in the SH. In MLT, annual peaks arise twice in each half of year. In 80-90 km, they're mainly in equinoctial seasons and winters: May, Aug.-Sep. and Jan. in the NH and Feb., Nov. and May in the SH. In 100-110 km, they emerge mainly in equinoctial seasons: Apr.-May and Aug.-Sep. in the NH and Feb.-Mar. and Oct.-Nov. in the SH. Then, inter-annual <span class="hlt">variations</span> of 6.5DW amplitudes during the 14-year period are studied. Frequency spectra of monthly-mean amplitudes show that, main dynamics in long-term <span class="hlt">variations</span> of 6.5DWs are AO and SAO in both hemispheres. Besides, QBO are visible in both hemispheres and 4-month period signals are noticed in the NH in MLT. Amplitudes of SAO, AO and QBO are obtained by bandpass filter. Their amplitudes are comparable in stratosphere and mesosphere, and QBO signals are weaker than the others in the LT. Vertical <span class="hlt">variations</span> both of SAO and AO amplitudes are very stable. AO structures have little inter-annual changes, while inter-annual <span class="hlt">variations</span> of SAO are significant and are related with 6.5DW. It means that annual and inter-annual <span class="hlt">variations</span> of 6.5DW are mainly controlled by AO and SAO, respectively. Although QBO signals are weaker and their <span class="hlt">variations</span> are less regular than AO and SAO, their phases seems to relate with inter-annual <span class="hlt">variations</span> of 6.5DW as well.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.S41A2152T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.S41A2152T"><span>Shear <span class="hlt">Wave</span> Velocity Structure beneath the African-Anatolian Subduction Zone in Southwestern Turkey from Inversions of Rayleigh <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Teoman, U. M.; Sandvol, E. A.; Kahraman, M.; Sahin, S.; Turkelli, N.</p> <p>2011-12-01</p> <p>The ongoing subduction of the African Plate under western Anatolia results in a highly complex tectonic structure especially beneath Isparta Angle (IA) and the surroundings where the Hellenic and Cyprian slabs with different subduction geometries intersect. The primary objective is to <span class="hlt">accurately</span> image the lithospheric structure at this convergent plate boundary and further understand the reasons responsible for the active deformation. Data was gathered from a temporary seismic network consisting of 10 broadband stations that was installed in August 2006 with the support from University of Missouri and nine more stations deployed in March 2007 with the support from Bogazici Research Fund (project ID:07T203). In addition, 21 permanent stations of Kandilli Observatory and Earthquake Research Institute (KOERI) and two from Süleyman Demirel University (SDU) together with five stations from IRIS/Geofon Network were also included to extend the station coverage. We used earthquakes in a distance range of 30-120 degrees with body <span class="hlt">wave</span> magnitudes larger than 5.5. Depending on the signal to noise ratio, azimuthal coverage of events, and coherence from station, 81 events provided high-quality data for our analysis. The distribution of events shows a good azimuthal coverage, which is important for resolving both lateral heterogeneity and azimuthal anisotropy. We adopted a two-plane-<span class="hlt">wave</span> inversion technique of Forsyth and Li (2003) to simultaneously solve for the incoming <span class="hlt">wave</span> field and phase velocity. This relatively simpler representation of a more complex wavefield provided quite stable patterns of amplitude <span class="hlt">variations</span> in many cases. To begin with, an average phase velocity dispersion curve was obtained and used as an input for tomographic inversions. Two-dimensional tomographic maps of isotropic and azimuthally anisotropic phase velocity <span class="hlt">variations</span> were generated. Phase velocities can only tell us integrated information about the upper mantle. Furthermore, we inverted phase</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070005090','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070005090"><span>Modeling the Observed Solar Cycle <span class="hlt">Variations</span> of the Quasi-biennial Oscillation (QBO): Amplification by <span class="hlt">Wave</span> Forcing</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mayr, Hans G.; Mengel, John G.; Huang, Frank T.; Chan, Kwing L.</p> <p>2007-01-01</p> <p>In several papers, the solar cycle (SC) effect in the lower atmosphere has been linked observationally to the Quasi-biennial Oscillation (QBO) of the zonal circulation, which is generated primarily by small-scale gravity <span class="hlt">waves</span> (GW). Salby and Callaghan (2000) in particular analyzed the QBO, covering more than 40 years, and discovered that it contains a large SC signature at 20 km. With our Numerical Spectral Model (NSM), we conducted a 3D study to describe the QBO under the influence of the SC, and some results have been published (Mayr et al., GRL, 2005,2006). For a SC period of 10 years, the relative amplitude of radiative forcing is taken to vary exponentially with height, i.e., 0.2% at the surface, 2% at 50 km, 20% at 100 km and above. Applying spectral analysis to filter out and identify the SC signature, the model generates a relatively large modulation of the QBO, which reproduces the observations qualitatively. Our numerical results demonstrate that the modulation of the QBO, with constant phase relative to the SC, persist at least for 60 years. The same model run generates in the seasonal <span class="hlt">variations</span> a hemispherically symmetric Equatorial Annual Oscillation (EAO, with 12-month period), which is confined to low latitudes like the QBO and is also modulated by the SC. Although the amplitude of the EAO is relatively small, its SC modulation is large, and it is in phase with that of the QBO. The SC modulated EAO is evidently the pathway and pacemaker for the solar influence on the QBO. To shed light on the dynamical processes involved, we present model results that show how the seasonal cycle induces the SC modulations of the EAO and QBO. Our analysis further demonstrates that the SC modulations of the QBO and EAO are amplified by the GW interaction with the flow. The GW momentum source clearly shows a SC modulation that is in phase with the corresponding modulations of the QBO and EAO. By tapping the momentum from the upward propagating GWs, the QBO and EAO</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.S23D0188R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.S23D0188R"><span><span class="hlt">Variation</span> of Fundamental Mode Surface <span class="hlt">Wave</span> Group Velocity Dispersion in Iran and the Surrounding Region</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rham, D. J.; Preistley, K.; Tatar, M.; Paul, A.</p> <p>2006-12-01</p> <p>We present group velocity dispersion results from a study of regional fundamental mode Rayleigh and Love <span class="hlt">waves</span> propagating across Iran and the surrounding region. Data for these measurements comes from field deployments within Iran by the University of Cambridge (GBR) and the Universite Joseph-Fourier (FRA) in conjunction with International Institute of Earthquake Engineering and Seismology (Iran), in addition to data from IRIS and Geofone. 1D path- averaged dispersion measurements have been made for ~5500 source-receiver paths using multiple filter analysis. We combine these observations in a tomographic inversion to produce group velocity images between 10 and 60 s period. Because of the dense path coverage, these images have substantially higher lateral resolution for this region than is currently available from global and regional group velocity studies. We observe <span class="hlt">variations</span> in short-period <span class="hlt">wave</span> group velocity which is consistent with the surface geology. Low group velocities (2.00-2.55 km/s) at short periods (10-20 s), for both Rayleigh and Love <span class="hlt">waves</span> are observed beneath thick sedimentary deposits; The south Caspian Basin, Black Sea, the eastern Mediterranean, the Persian Gulf, the Makran, the southern Turan shield, and the Indus and Gangetic basins. Somewhat higher group velocity (2.80-3.15 km/s for Rayleigh, and 3.00-3.40 km/s for Love) at these periods occur in sediment poor regions, such as; the Turkish-Iranian plateau, the Arabian shield, and Kazakhstan. At intermediate periods (30-40 s) group velocities over most of the region are low (2.65-3.20 km/s for Rayleigh, and 2.80-3.45 km/s for love) compared to Arabia (3.40-3.70 km/s Rayleigh, 3.50-4.0 km/s Love). At longer periods (50-60 s) Love <span class="hlt">wave</span> group velocities remain low (3.25-3.70 km/s) over most of Iran, but there are even lower velocities (2.80-3.00 km/s) still associated with the thick sediments of the south Caspian basin, the surrounding shield areas have much higher group velocities (3</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017CSR...139...35D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017CSR...139...35D"><span>The effects of tropical cyclone characteristics on the surface <span class="hlt">wave</span> fields in Australia's North West region</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Drost, Edwin J. F.; Lowe, Ryan J.; Ivey, Greg N.; Jones, Nicole L.; Péquignet, Christine A.</p> <p>2017-05-01</p> <p>The numerical <span class="hlt">wave</span> model SWAN (Simulating <span class="hlt">WAves</span> Nearshore) and historical <span class="hlt">wave</span> buoy observations were used to investigate the response of surface <span class="hlt">wave</span> fields to tropical cyclone (TC) wind forcing on the Australian North West Shelf (NWS). Analysis of historical <span class="hlt">wave</span> data during TC events at a key location on the NWS showed that an average of 1.7 large TCs impacted the region each year, albeit with high variability in TC track, intensity and size, and also in the surface <span class="hlt">wave</span> field response. An <span class="hlt">accurately</span> modeled TC wind field resulted in a good prediction of the observed extreme <span class="hlt">wave</span> conditions by SWAN. Results showed that the presence of strong background winds during a TC and a long TC lifetime (with large <span class="hlt">variations</span> in translation speed) can provide additional energy input. This potentially enhances the generated swell <span class="hlt">waves</span> and increases the spatial extent of the TC generated surface <span class="hlt">wave</span> fields. For the TC translation speeds in this study, a positive relationship between TC translation speed and the resulting maximum significant <span class="hlt">wave</span> height and <span class="hlt">wave</span> field asymmetry was observed. Bottom friction across the wide NWS limited the amount of <span class="hlt">wave</span> energy reaching the coastal region; consistently reducing <span class="hlt">wave</span> energy in depths below 50 m, and in the case of the most extreme conditions, in depths up to 100 m that comprise much of the shelf. Nevertheless, whitecapping was still the dominant dissipation mechanism on the broader shelf region. Shelf-scale refraction had little effect on the amount of <span class="hlt">wave</span> energy reaching the nearshore zone; however, refraction locally enhanced or reduced <span class="hlt">wave</span> energy depending on the orientation of the isobaths with respect to the dominant <span class="hlt">wave</span> direction during the TC.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/sciencecinema/biblio/1057555','SCIGOVIMAGE-SCICINEMA'); return false;" href="http://www.osti.gov/sciencecinema/biblio/1057555"><span>PNNL Expert Doug McMakin Discusses Millimeter <span class="hlt">Wave</span> Technology</span></a></p> <p><a target="_blank" href="http://www.osti.gov/sciencecinema/">ScienceCinema</a></p> <p>McMakin, Doug</p> <p>2018-02-13</p> <p>Electrical Engineer Doug McMakin discusses Millimeter <span class="hlt">Wave</span> Holographic technology, which uses non-harmful, ultrahigh-frequency radio <span class="hlt">waves</span> to penetrate clothing to detect and identify concealed objects, as well as obtain <span class="hlt">accurate</span> body measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19740020296','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740020296"><span>On numerically <span class="hlt">accurate</span> finite element</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nagtegaal, J. C.; Parks, D. M.; Rice, J. R.</p> <p>1974-01-01</p> <p>A general criterion for testing a mesh with topologically similar repeat units is given, and the analysis shows that only a few conventional element types and arrangements are, or can be made suitable for computations in the fully plastic range. Further, a new <span class="hlt">variational</span> principle, which can easily and simply be incorporated into an existing finite element program, is presented. This allows <span class="hlt">accurate</span> computations to be made even for element designs that would not normally be suitable. Numerical results are given for three plane strain problems, namely pure bending of a beam, a thick-walled tube under pressure, and a deep double edge cracked tensile specimen. The effects of various element designs and of the new <span class="hlt">variational</span> procedure are illustrated. Elastic-plastic computation at finite strain are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17677566','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17677566"><span>Traveling <span class="hlt">waves</span> in a magnetized Taylor-Couette flow.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liu, Wei; Goodman, Jeremy; Ji, Hantao</p> <p>2007-07-01</p> <p>We investigate numerically a traveling <span class="hlt">wave</span> pattern observed in experimental magnetized Taylor-Couette flow at low magnetic Reynolds number. By <span class="hlt">accurately</span> modeling viscous and magnetic boundaries in all directions, we reproduce the experimentally measured <span class="hlt">wave</span> patterns and their amplitudes. Contrary to previous claims, the <span class="hlt">waves</span> are shown to be transiently amplified disturbances launched by viscous boundary layers, rather than globally unstable magnetorotational modes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1980PhRvB..22.5987S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1980PhRvB..22.5987S"><span>Hartree-Fock theory of the inhomogeneous electron gas at a jellium metal surface: Rigorous upper bounds to the surface energy and <span class="hlt">accurate</span> work functions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sahni, V.; Ma, C. Q.</p> <p>1980-12-01</p> <p>The inhomogeneous electron gas at a jellium metal surface is studied in the Hartree-Fock approximation by Kohn-Sham density functional theory. Rigorous upper bounds to the surface energy are derived by application of the Rayleigh-Ritz <span class="hlt">variational</span> principle for the energy, the surface kinetic, electrostatic, and nonlocal exchange energy functionals being determined exactly for the <span class="hlt">accurate</span> linear-potential model electronic <span class="hlt">wave</span> functions. The densities obtained by the energy minimization constraint are then employed to determine work-function results via the <span class="hlt">variationally</span> <span class="hlt">accurate</span> "displaced-profile change-in-self-consistent-field" expression. The theoretical basis of this non-self-consistent procedure and its demonstrated accuracy for the fully correlated system (as treated within the local-density approximation for exchange and correlation) leads us to conclude these results for the surface energies and work functions to be essentially exact. Work-function values are also determined by the Koopmans'-theorem expression, both for these densities as well as for those obtained by satisfaction of the constraint set on the electrostatic potential by the Budd-Vannimenus theorem. The use of the Hartree-Fock results in the <span class="hlt">accurate</span> estimation of correlation-effect contributions to these surface properties of the nonuniform electron gas is also indicated. In addition, the original work and approximations made by Bardeen in this attempt at a solution of the Hartree-Fock problem are briefly reviewed in order to contrast with the present work.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1981AnG....37..539C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1981AnG....37..539C"><span>Amplitude <span class="hlt">variations</span> during SIDs in 10.2 and 13.6 kHz <span class="hlt">waves</span> propagating long distances in the subionospheric waveguide - Theoretical interpretation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Charcosset, G.; Tixier, M.</p> <p>1981-12-01</p> <p>During sudden ionospheric disturbances (SIDs), vertical electric field amplitude <span class="hlt">variations</span> of <span class="hlt">waves</span> emitted at 10.2 and 13.6 kHz in Norway and Liberia and observed in France were found to result in a regular decrease at the former wavelength and more complex behavior at the latter, where amplitude behavior depends on the importance of the SID. A theoretical interpretation employing a waveguide mode hypothesis of long distance <span class="hlt">wave</span> propagation is presented, in which it is assumed that the D-region ionization enhancement produced by the solar X-ray flux during SID can be represented by a decrease of the waveguide height in which the shape of the density profile remains unchanged.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009pcms.confE.126C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009pcms.confE.126C"><span>Trend analysis of the <span class="hlt">wave</span> storminess: the <span class="hlt">wave</span> direction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Casas Prat, M.; Sierra, J. P.; Mösso, C.; Sánchez-Arcilla, A.</p> <p>2009-09-01</p> <p>Climate change has an important role in the current scientific research because of its possible future negative consequences. Concerning the climate change in the coastal engineering field, the apparent sea level rise is one of the key parameters as well as the <span class="hlt">wave</span> height and the <span class="hlt">wave</span> direction temporal <span class="hlt">variations</span>. According to the IPCC (2007), during the last century the sea level has been increasing with a mean rate of 1.7 ± 0.5 mm/yr. However, at local/regional scale the tendency significantly differs from the global trend since the local pressure and wind field <span class="hlt">variations</span> become more relevant. This appears to be particularly significant in semi-enclosed areas in the Mediterranean Sea (Cushman-Roisin et al., 2001). Even though the existing unsolved questions related to the sea level rise, the uncertainty concerning the <span class="hlt">wave</span> height is even larger, in which stormy conditions are especially important because they are closely related to processes such as coastal erosion, flooding, etc. Therefore, it is necessary to identify possible existing tendencies of storm related parameters. In many studies, only the maximum <span class="hlt">wave</span> height and storm duration are analysed, remaining the <span class="hlt">wave</span> direction in a second term. Note that a possible rotation of the mean <span class="hlt">wave</span> direction may involve severe consequences since most beach and harbour defence structures have been designed assuming a constant predominant <span class="hlt">wave</span> incidence. Liste et al. (2004) illustrated this fact with an example in which a rotation of only 2 degrees of the mean energy flux vector could produce a beach retreat of 20 m. Another possible consequence would be a decrease of the harbour operability: increased frequency of storms in the same direction as the harbour entrance orientation would influence the navigability. The present study, which focuses in the Catalan coast (NW Mediterranean Sea), aims to improve the present knowledge of the <span class="hlt">wave</span> storminess <span class="hlt">variations</span> at regional scale, specially focusing on the <span class="hlt">wave</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ClDy...50.4285C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ClDy...50.4285C"><span>California heat <span class="hlt">waves</span>: their spatial evolution, <span class="hlt">variation</span>, and coastal modulation by low clouds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Clemesha, Rachel E. S.; Guirguis, Kristen; Gershunov, Alexander; Small, Ivory J.; Tardy, Alexander</p> <p>2018-06-01</p> <p>We examine the spatial and temporal evolution of heat <span class="hlt">waves</span> through California and consider one of the key modulating factors of summertime coastal climate—coastal low cloudiness (CLC). Heat <span class="hlt">waves</span> are defined relative to daytime maximum temperature (Tmax) anomalies after removing local seasonality and capture unseasonably warm events during May—September. California is home to several diverse climate regions and characteristics of extreme heat events are also variable throughout these regions. Heat <span class="hlt">wave</span> events tend to be shorter, but more anomalously intense along the coast. Heat <span class="hlt">waves</span> typically impact both coastal and inland regions, although there is more propensity towards coastally trapped events. Most heat <span class="hlt">waves</span> with a strong impact across regions start at the coast, proceed inland, and weaken at the coast before letting up inland. Typically, the beginning of coastal heat <span class="hlt">waves</span> are associated with a loss of CLC, followed by a strong rebound of CLC starting close to the peak in heat <span class="hlt">wave</span> intensity. The degree to which an inland heat <span class="hlt">wave</span> is expressed at the coast is associated with the presence of these low clouds. Inland heat <span class="hlt">waves</span> that have very little expression at the coast tend to have CLC present and an elevated inversion base height compared with other heat <span class="hlt">waves</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4700421','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4700421"><span>Visualization of terahertz surface <span class="hlt">waves</span> propagation on metal foils</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wang, Xinke; Wang, Sen; Sun, Wenfeng; Feng, Shengfei; Han, Peng; Yan, Haitao; Ye, Jiasheng; Zhang, Yan</p> <p>2016-01-01</p> <p>Exploitation of surface plasmonic devices (SPDs) in the terahertz (THz) band is always beneficial for broadening the application potential of THz technologies. To clarify features of SPDs, a practical characterization means is essential for <span class="hlt">accurately</span> observing the complex field distribution of a THz surface <span class="hlt">wave</span> (TSW). Here, a THz digital holographic imaging system is employed to coherently exhibit temporal <span class="hlt">variations</span> and spectral properties of TSWs activated by a rectangular or semicircular slit structure on metal foils. Advantages of the imaging system are comprehensively elucidated, including the exclusive measurement of TSWs and fall-off of the time consumption. Numerical simulations of experimental procedures further verify the imaging measurement accuracy. It can be anticipated that this imaging system will provide a versatile tool for analyzing the performance and principle of SPDs. PMID:26729652</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19990070932','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19990070932"><span><span class="hlt">Wave</span> Dynamics and Transport in the Stratosphere</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Holton, James R.; Alexander, M. Joan</p> <p>1999-01-01</p> <p>The report discusses: (1) Gravity <span class="hlt">waves</span> generated by tropical convection: A study in which a two-dimensional cloud-resolving model was used to examine the possible role of gravity <span class="hlt">waves</span> generated by a simulated tropical squall line in forcing the quasi-biennial oscillation was completed. (2) Gravity <span class="hlt">wave</span> ray tracing studies:It was developed a linear ray tracing model of gravity <span class="hlt">wave</span> propagation to extend the nonlinear storm model results into the mesosphere and thermosphere. (3) tracer filamentation: Vertical soundings of stratospheric ozone often exhibit laminated tracer structures characterized by strong vertical tracer gradients. (4) Mesospheric gravity <span class="hlt">wave</span> modeling studies: Although our emphasis in numerical simulation of gravity <span class="hlt">waves</span> generated by convection has shifted from simulation of idealized two-dimensional squall lines to the most realistic (and complex) study of <span class="hlt">wave</span> generation by three-dimensional storms. (5) Gravity <span class="hlt">wave</span> climatology studies: Mr. Alexander applied a linear gravity <span class="hlt">wave</span> propagation model together with observations of the background wind and stability fields to compute climatologies of gravity <span class="hlt">wave</span> activity for comparison to observations. (6) Convective forcing of gravity <span class="hlt">waves</span>: Theoretical study of gravity <span class="hlt">wave</span> forcing by convective heat sources has completed. (7) Gravity <span class="hlt">waves</span> observation from UARS: The objective of this work is to apply ray tracing, and other model technique, in order to determine to what extend the horizontal and vertical <span class="hlt">variation</span> in satellite observed distribution of small-scale temperature variance can be attributed to gravity <span class="hlt">waves</span> from particular sources. (8) The annual and interannual <span class="hlt">variations</span> in temperature and mass flux near the tropical tropopause. and (9) Three dimensional cloud model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMOS43A1395M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMOS43A1395M"><span>Simulating Freak <span class="hlt">Waves</span> in the Ocean with CFD Modeling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Manolidis, M.; Orzech, M.; Simeonov, J.</p> <p>2017-12-01</p> <p>Rogue, or freak, <span class="hlt">waves</span> constitute an active topic of research within the world scientific community, as various maritime authorities around the globe seek to better understand and more <span class="hlt">accurately</span> assess the risks that the occurrence of such phenomena entail. Several experimental studies have shed some light on the mechanics of rogue <span class="hlt">wave</span> formation. In our work we numerically simulate the formation of such <span class="hlt">waves</span> in oceanic conditions by means of Computational Fluid Dynamics (CFD) software. For this purpose we implement the NHWAVE and OpenFOAM software packages. Both are non-hydrostatic, turbulent flow solvers, but NHWAVE implements a shock-capturing scheme at the free surface-interface, while OpenFOAM utilizes the Volume Of Fluid (VOF) method. NHWAVE has been shown to <span class="hlt">accurately</span> reproduce highly nonlinear surface <span class="hlt">wave</span> phenomena, such as soliton propagation and <span class="hlt">wave</span> shoaling. We conducted a range of tests simulating rogue <span class="hlt">wave</span> formation and horizontally varying currents to evaluate and compare the capabilities of the two software packages. Then we used each model to investigate the effect of ocean currents and current gradients on the formation of rogue <span class="hlt">waves</span>. We present preliminary results.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27443581','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27443581"><span>Diagnostic Criteria for the Characterization of Electrode Reactions with Chemically Coupled Reactions Preceding the Electron Transfer by Cyclic Square <span class="hlt">Wave</span> Voltammetry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Helfrick, John C; Mann, Megan A; Bottomley, Lawrence A</p> <p>2016-08-18</p> <p>Theory for cyclic square <span class="hlt">wave</span> voltammetry of electrode reactions with chemical reactions preceding the electron transfer is presented. Theoretical voltammograms were calculated following systematic <span class="hlt">variation</span> of empirical parameters to assess their impact on the shape of the voltammogram. From the trends obtained, diagnostic criteria for this mechanism were deduced. When properly applied, these criteria will enable non-experts in voltammetry to assign the electrode reaction mechanism and <span class="hlt">accurately</span> measure reaction kinetics. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20000054670','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20000054670"><span>Sensitivity of a <span class="hlt">Wave</span> Structure to Initial Conditions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Duval, Walter M. B.; Duval, Walter M. B. (Technical Monitor)</p> <p>2000-01-01</p> <p>Microgravity experiments aimed at quantifying effects of gentler via controlled sinusoidal forcing transmitted on the interface between two miscible liquids have shown the evolution of a quasi -stationary four-mode <span class="hlt">wave</span> structure oriented vertically. The sensitivity of the <span class="hlt">wave</span> structure to phase angle <span class="hlt">variation</span> is investigated computationally. We show that a slight <span class="hlt">variation</span> of the phase angle is sufficient to cause a bifurcation to a two-mode structure. The dependence of phase angle on <span class="hlt">wave</span> structure is attributed to sensitivity on initial conditions due to the strong nonlinearity of the coupled field equations for the parametric space of interest.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSAH13A..06F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSAH13A..06F"><span>Climate-driven <span class="hlt">variations</span> in thermal forcing across a nearshore reef system during a marine heat <span class="hlt">wave</span> and its potential impact on coral calcification</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Falter, J.; Zhang, Z.; Lowe, R.; Foster, T.; McCulloch, M. T.</p> <p>2016-02-01</p> <p>We examined the oceanic and atmospheric forces driving seasonal and spatial variability in water temperature across backreef and lagoonal habitats at Coral Bay at Ningaloo Reef, Western Australia before, during, and after a historically unprecedented marine heat <span class="hlt">wave</span> and resulting mass bleaching event in 2010-2011. Local deviations in the mean daily temperature of nearshore reef waters from offshore values were a linear function of the combined effect of net atmospheric heating and offshore <span class="hlt">wave</span> height and period . While intra-annual <span class="hlt">variation</span> in local heat exchange was driven mainly by seasonal changes in short-<span class="hlt">wave</span> radiation; intra-annual <span class="hlt">variation</span> in local cooling was driven mostly by changes in relative humidity (r2 = 0.60) and wind speed (r2 = 0.31) which exhibited no apparent seasonality. We demonstrate good agreement between nearshore reef temperatures modeled from offshore sea surface temperatures (SST), offshore <span class="hlt">wave</span> forcing, and local atmospheric heat fluxes with observed temperatures using a simple linear model (r2 = 0.31 to 0.69, root-mean-square error = 0.4°C to 0.9°C). Using these modeled nearshore reef temperature records, we show that during the heat <span class="hlt">wave</span> local thermal stresses across the reef reached as high as 18-34 °C-weeks and were being both intensified and accelerated by regional climate forcing when compared with offshore waters (12.6 °C-weeks max). Measurements of coral calcification made in Coral Bay following the bleaching event appear to lack any distinct seasonality; possibly due to the long-term effects of acute thermal stress. However, similarly minimal seasonality in calcification rates had also been observed in an Acropora-dominated community at Ningaloo years before the heat <span class="hlt">wave</span> as well as more recently in coral from regions in WA that had avoided mass bleaching. These observations, in conjunction with observations that most of the bleached communities within Coral Bay had recovered their color within 3-6 months of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70026753','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70026753"><span>Utilization of high-frequency Rayleigh <span class="hlt">waves</span> in near-surface geophysics</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Xia, J.; Miller, R.D.; Park, C.B.; Ivanov, J.; Tian, G.; Chen, C.</p> <p>2004-01-01</p> <p>Shear-<span class="hlt">wave</span> velocities can be derived from inverting the dispersive phase velocity of the surface. The multichannel analysis of surface <span class="hlt">waves</span> (MASW) is one technique for inverting high-frequency Rayleigh <span class="hlt">waves</span>. The process includes acquisition of high-frequency broad-band Rayleigh <span class="hlt">waves</span>, efficient and <span class="hlt">accurate</span> algorithms designed to extract Rayleigh-<span class="hlt">wave</span> dispersion curves from Rayleigh <span class="hlt">waves</span>, and stable and efficient inversion algorithms to obtain near-surface S-<span class="hlt">wave</span> velocity profiles. MASW estimates S-<span class="hlt">wave</span> velocity from multichannel vertical compoent data and consists of data acquisition, dispersion-curve picking, and inversion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3857859','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3857859"><span>Transversally periodic solitary gravity–capillary <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Milewski, Paul A.; Wang, Zhan</p> <p>2014-01-01</p> <p>When both gravity and surface tension effects are present, surface solitary water <span class="hlt">waves</span> are known to exist in both two- and three-dimensional infinitely deep fluids. We describe here solutions bridging these two cases: travelling <span class="hlt">waves</span> which are localized in the propagation direction and periodic in the transverse direction. These transversally periodic gravity–capillary solitary <span class="hlt">waves</span> are found to be of either elevation or depression type, tend to plane <span class="hlt">waves</span> below a critical transverse period and tend to solitary lumps as the transverse period tends to infinity. The <span class="hlt">waves</span> are found numerically in a Hamiltonian system for water <span class="hlt">waves</span> simplified by a cubic truncation of the Dirichlet-to-Neumann operator. This approximation has been proved to be very <span class="hlt">accurate</span> for both two- and three-dimensional computations of fully localized gravity–capillary solitary <span class="hlt">waves</span>. The stability properties of these <span class="hlt">waves</span> are then investigated via the time evolution of perturbed <span class="hlt">wave</span> profiles. PMID:24399922</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3665267','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3665267"><span>Improving Thermal Ablation Delineation With Electrode Vibration Elastography Using a Bidirectional <span class="hlt">Wave</span> Propagation Assumption</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>DeWall, Ryan J.; Varghese, Tomy</p> <p>2013-01-01</p> <p>Thermal ablation procedures are commonly used to treat hepatic cancers and <span class="hlt">accurate</span> ablation representation on shear <span class="hlt">wave</span> velocity images is crucial to ensure complete treatment of the malignant target. Electrode vibration elastography is a shear <span class="hlt">wave</span> imaging technique recently developed to monitor thermal ablation extent during treatment procedures. Previous work has shown good lateral boundary delineation of ablated volumes, but axial delineation was more ambiguous, which may have resulted from the assumption of lateral shear <span class="hlt">wave</span> propagation. In this work, we assume both lateral and axial <span class="hlt">wave</span> propagation and compare <span class="hlt">wave</span> velocity images to those assuming only lateral shear <span class="hlt">wave</span> propagation in finite element simulations, tissue-mimicking phantoms, and bovine liver tissue. Our results show that assuming bidirectional <span class="hlt">wave</span> propagation minimizes artifacts above and below ablated volumes, yielding a more <span class="hlt">accurate</span> representation of the ablated region on shear <span class="hlt">wave</span> velocity images. Area overestimation was reduced from 13.4% to 3.6% in a stiff-inclusion tissue-mimicking phantom and from 9.1% to 0.8% in a radio-frequency ablation in bovine liver tissue. More <span class="hlt">accurate</span> ablation representation during ablation procedures increases the likelihood of complete treatment of the malignant target, decreasing tumor recurrence. PMID:22293748</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22293748','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22293748"><span>Improving thermal ablation delineation with electrode vibration elastography using a bidirectional <span class="hlt">wave</span> propagation assumption.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>DeWall, Ryan J; Varghese, Tomy</p> <p>2012-01-01</p> <p>Thermal ablation procedures are commonly used to treat hepatic cancers and <span class="hlt">accurate</span> ablation representation on shear <span class="hlt">wave</span> velocity images is crucial to ensure complete treatment of the malignant target. Electrode vibration elastography is a shear <span class="hlt">wave</span> imaging technique recently developed to monitor thermal ablation extent during treatment procedures. Previous work has shown good lateral boundary delineation of ablated volumes, but axial delineation was more ambiguous, which may have resulted from the assumption of lateral shear <span class="hlt">wave</span> propagation. In this work, we assume both lateral and axial <span class="hlt">wave</span> propagation and compare <span class="hlt">wave</span> velocity images to those assuming only lateral shear <span class="hlt">wave</span> propagation in finite element simulations, tissue-mimicking phantoms, and bovine liver tissue. Our results show that assuming bidirectional <span class="hlt">wave</span> propagation minimizes artifacts above and below ablated volumes, yielding a more <span class="hlt">accurate</span> representation of the ablated region on shear <span class="hlt">wave</span> velocity images. Area overestimation was reduced from 13.4% to 3.6% in a stiff-inclusion tissue-mimicking phantom and from 9.1% to 0.8% in a radio-frequency ablation in bovine liver tissue. More <span class="hlt">accurate</span> ablation representation during ablation procedures increases the likelihood of complete treatment of the malignant target, decreasing tumor recurrence. © 2012 IEEE</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22680108-probing-pre-inflationary-anisotropy-directional-variations-gravitational-wave-background','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22680108-probing-pre-inflationary-anisotropy-directional-variations-gravitational-wave-background"><span>Probing pre-inflationary anisotropy with directional <span class="hlt">variations</span> in the gravitational <span class="hlt">wave</span> background</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Furuya, Yu; Niiyama, Yuki; Sendouda, Yuuiti, E-mail: furuya@tap.st.hirosaki-u.ac.jp, E-mail: niiyama@tap.st.hirosaki-u.ac.jp, E-mail: sendouda@hirosaki-u.ac.jp</p> <p></p> <p>We perform a detailed analysis on a primordial gravitational-<span class="hlt">wave</span> background amplified during a Kasner-like pre-inflationary phase allowing for general triaxial anisotropies. It is found that the predicted angular distribution map of gravitational-<span class="hlt">wave</span> intensity on large scales exhibits topologically distinctive patterns according to the degree of the pre-inflationary anisotropy, thereby serving as a potential probe for the pre-inflationary early universe with future all-sky observations of gravitational <span class="hlt">waves</span>. We also derive an observational limit on the amplitude of such anisotropic gravitational <span class="hlt">waves</span> from the B -mode polarisation of the cosmic microwave background.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRB..123.1516P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRB..123.1516P"><span>High-Resolution Rayleigh <span class="hlt">Wave</span> Group Velocity <span class="hlt">Variation</span> Beneath Greenland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pourpoint, Maeva; Anandakrishnan, Sridhar; Ammon, Charles J.</p> <p>2018-02-01</p> <p>We present a high-resolution group velocity model of Greenland from the analysis of fundamental mode Rayleigh <span class="hlt">waves</span>. Regional and teleseismic events recorded by the Greenland Ice Sheet Monitoring Network seismic network were used and we developed a group velocity correction method to estimate the dispersion within our region of study. The global dispersion model GDM52 from Ekström (2011, https://doi.org/10.1111/j.1365-246X.2011.05225.x) was used to calculate group delays from the earthquake to the boundaries of our study area. An iterative reweighted generalized least squares approach was then used to invert for the regional group velocity <span class="hlt">variations</span> between periods of 25 s and 180 s. The group delay correction method helps alleviate the limitations of the sparse Greenland seismic network in a region with poor seismicity. Both the ray coverage and resolution of our model are significantly better than similar studies of Greenland using two-station methods. Spike tests suggest that features as small as 200 km can be resolved across Greenland. Our dispersion maps are consistent with previous studies and reveal many signatures of known geologic features including known sedimentary basins in Baffin Bay, the West and East Greenland flood basalt provinces, the East and South Greenland Archean blocks. Our model also contains two prominent features: a deep high-velocity anomaly extending from northwestern to southwestern Greenland that could be the signature of a cratonic root and a low-velocity anomaly in central eastern Greenland that correlates with the Icelandic plume track and could be associated with lithospheric thinning and upwelling of hot asthenosphere material.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PlST...19h4002H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PlST...19h4002H"><span>An <span class="hlt">accurate</span> automated technique for quasi-optics measurement of the microwave diagnostics for fusion plasma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hu, Jianqiang; Liu, Ahdi; Zhou, Chu; Zhang, Xiaohui; Wang, Mingyuan; Zhang, Jin; Feng, Xi; Li, Hong; Xie, Jinlin; Liu, Wandong; Yu, Changxuan</p> <p>2017-08-01</p> <p>A new integrated technique for fast and <span class="hlt">accurate</span> measurement of the quasi-optics, especially for the microwave/millimeter <span class="hlt">wave</span> diagnostic systems of fusion plasma, has been developed. Using the LabVIEW-based comprehensive scanning system, we can realize not only automatic but also fast and <span class="hlt">accurate</span> measurement, which will help to eliminate the effects of temperature drift and standing <span class="hlt">wave</span>/multi-reflection. With the Matlab-based asymmetric two-dimensional Gaussian fitting method, all the desired parameters of the microwave beam can be obtained. This technique can be used in the design and testing of microwave diagnostic systems such as reflectometers and the electron cyclotron emission imaging diagnostic systems of the Experimental Advanced Superconducting Tokamak.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70196193','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70196193"><span>Nonhydrostatic and surfbeat model predictions of extreme <span class="hlt">wave</span> run-up in fringing reef environments</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Lashley, Christopher H.; Roelvink, Dano; van Dongeren, Ap R.; Buckley, Mark L.; Lowe, Ryan J.</p> <p>2018-01-01</p> <p>The <span class="hlt">accurate</span> prediction of extreme <span class="hlt">wave</span> run-up is important for effective coastal engineering design and coastal hazard management. While run-up processes on open sandy coasts have been reasonably well-studied, very few studies have focused on understanding and predicting <span class="hlt">wave</span> run-up at coral reef-fronted coastlines. This paper applies the short-<span class="hlt">wave</span> resolving, Nonhydrostatic (XB-NH) and short-<span class="hlt">wave</span> averaged, Surfbeat (XB-SB) modes of the XBeach numerical model to validate run-up using data from two 1D (alongshore uniform) fringing-reef profiles without roughness elements, with two objectives: i) to provide insight into the physical processes governing run-up in such environments; and ii) to evaluate the performance of both modes in <span class="hlt">accurately</span> predicting run-up over a wide range of conditions. XBeach was calibrated by optimizing the maximum <span class="hlt">wave</span> steepness parameter (maxbrsteep) in XB-NH and the dissipation coefficient (alpha) in XB-SB) using the first dataset; and then applied to the second dataset for validation. XB-NH and XB-SB predictions of extreme <span class="hlt">wave</span> run-up (Rmax and R2%) and its components, infragravity- and sea-swell band swash (SIG and SSS) and shoreline setup (<η>), were compared to observations. XB-NH more <span class="hlt">accurately</span> simulated <span class="hlt">wave</span> transformation but under-predicted shoreline setup due to its exclusion of parameterized <span class="hlt">wave</span>-roller dynamics. XB-SB under-predicted sea-swell band swash but overestimated shoreline setup due to an over-prediction of <span class="hlt">wave</span> heights on the reef flat. Run-up (swash) spectra were dominated by infragravity motions, allowing the short-<span class="hlt">wave</span> (but not <span class="hlt">wave</span> group) averaged model (XB-SB) to perform comparably well to its more complete, short-<span class="hlt">wave</span> resolving (XB-NH) counterpart. Despite their respective limitations, both modes were able to <span class="hlt">accurately</span> predict Rmax and R2%.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012DPS....4451103N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012DPS....4451103N"><span>Density <span class="hlt">Wave</span> Signatures In VIMS Spectral Data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nicholson, Philip D.; Hedman, M. M.; Cassini VIMS Team</p> <p>2012-10-01</p> <p>Spectral scans of Saturn's rings by the Cassini VIMS instrument have revealed both regional and local <span class="hlt">variations</span> in the depths of the water ice bands at 1.5 and 2.0 microns, which have been interpreted in terms of <span class="hlt">variations</span> in regolith grain size and the amount of non-icy "contaminants" (Filacchione et al. 2012; Hedman et al. 2012). Noteworthy among the local <span class="hlt">variations</span> are distinctive patterns associated with the four strong density <span class="hlt">waves</span> in the A ring. Within each wavetrain there is a peak in band strength relative to the surrounding material, while extending on both sides of the <span class="hlt">wave</span> is a "halo" of reduced band strength. The typical width of these haloes is 400-500 km, about 2-3 times the visible extent of the density <span class="hlt">waves</span>. The origin of these features is unknown, but may involve enhanced collisional erosion in the <span class="hlt">wave</span> zones and transport of the smaller debris into nearby regions. A similar pattern of band depth <span class="hlt">variations</span> is also seen at several locations in the more opaque B ring in association with the strong 3:2 ILRs of Janus, Pandora and Prometheus. The former shows a pattern just like its siblings in the A ring, while the latter two resonances show haloes, but without central peaks. In each case, the radial widths of the halo approaches 1000 km, but stellar occultation profiles show no detectable density wavetrain. We suggest that this spectral signature may be a useful diagnostic for the presence of strong density <span class="hlt">waves</span> in regions where the rings are too opaque for occultations to reveal a typical <span class="hlt">wave</span> profile. More speculatively, the displacement of the haloes' central radii from the calculated ILR locations of 600-700 km could imply a surface density in the central B ring in excess of 500 g/cm^2. This research was supported by the Cassini/Huygens project.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910071468&hterms=chemical+reactions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dchemical%2Breactions','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910071468&hterms=chemical+reactions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dchemical%2Breactions"><span>Improved techniques for outgoing <span class="hlt">wave</span> <span class="hlt">variational</span> principle calculations of converged state-to-state transition probabilities for chemical reactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mielke, Steven L.; Truhlar, Donald G.; Schwenke, David W.</p> <p>1991-01-01</p> <p>Improved techniques and well-optimized basis sets are presented for application of the outgoing <span class="hlt">wave</span> <span class="hlt">variational</span> principle to calculate converged quantum mechanical reaction probabilities. They are illustrated with calculations for the reactions D + H2 yields HD + H with total angular momentum J = 3 and F + H2 yields HF + H with J = 0 and 3. The optimization involves the choice of distortion potential, the grid for calculating half-integrated Green's functions, the placement, width, and number of primitive distributed Gaussians, and the computationally most efficient partition between dynamically adapted and primitive basis functions. Benchmark calculations with 224-1064 channels are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19780012312','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19780012312"><span>Correlation of Fiber Composite Tensile Strength with the Ultrasonic Stress <span class="hlt">Wave</span> Factor</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Vary, A.; Lark, R. F.</p> <p>1978-01-01</p> <p>An ultrasonic-acoustic technique was used to indicate the strength <span class="hlt">variations</span> of tensile specimens of a graphite-epoxy composite. A stress <span class="hlt">wave</span> factor was determined and its value was found to depend on <span class="hlt">variations</span> of the fiber-resin bonding as well as fiber orientation. The fiber orientations studied were 0 deg (longitudinal), 10 deg (off-axis), 90 deg (transverse), 0 deg + or - 45 deg/0 deg symmetrical, and + or - 45 deg] symmetrical. The stress <span class="hlt">wave</span> factor can indicate <span class="hlt">variations</span> of the tensile and shear strengths of composite materials. The stress <span class="hlt">wave</span> factor was also found to be sensitive to strength <span class="hlt">variations</span> associated with microporosity and differences in fiber-resin ratio.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JAG...152..167T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JAG...152..167T"><span><span class="hlt">Wave</span> equation datuming applied to S-<span class="hlt">wave</span> reflection seismic data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tinivella, U.; Giustiniani, M.; Nicolich, R.</p> <p>2018-05-01</p> <p>S-<span class="hlt">wave</span> high-resolution reflection seismic data was processed using <span class="hlt">Wave</span> Equation Datuming technique in order to improve signal/noise ratio, attenuating coherent noise, and seismic resolution and to solve static corrections problems. The application of this algorithm allowed obtaining a good image of the shallow subsurface geological features. <span class="hlt">Wave</span> Equation Datuming moves shots and receivers from a surface to another datum (the datum plane), removing time shifts originated by elevation <span class="hlt">variation</span> and/or velocity changes in the shallow subsoil. This algorithm has been developed and currently applied to P <span class="hlt">wave</span>, but it reveals the capacity to highlight S-<span class="hlt">waves</span> images when used to resolve thin layers in high-resolution prospecting. A good S-<span class="hlt">wave</span> image facilitates correlation with well stratigraphies, optimizing cost/benefit ratio of any drilling. The application of <span class="hlt">Wave</span> Equation Datuming requires a reliable velocity field, so refraction tomography was adopted. The new seismic image highlights the details of the subsoil reflectors and allows an easier integration with borehole information and geological surveys than the seismic section obtained by conventional CMP reflection processing. In conclusion, the analysis of S-<span class="hlt">wave</span> let to characterize the shallow subsurface recognizing levels with limited thickness once we have clearly attenuated ground roll, wind and environmental noise.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhTea..55..232V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhTea..55..232V"><span>Standing <span class="hlt">Waves</span> in an Elastic Spring: A Systematic Study by Video Analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ventura, Daniel Rodrigues; de Carvalho, Paulo Simeão; Dias, Marco Adriano</p> <p>2017-04-01</p> <p>The word "<span class="hlt">wave</span>" is part of the daily language of every student. However, the physical understanding of the concept demands a high level of abstract thought. In physics, <span class="hlt">waves</span> are oscillating <span class="hlt">variations</span> of a physical quantity that involve the transfer of energy from one point to another, without displacement of matter. A <span class="hlt">wave</span> can be formed by an elastic deformation, a <span class="hlt">variation</span> of pressure, changes in the intensity of electric or magnetic fields, a propagation of a temperature <span class="hlt">variation</span>, or other disturbances. Moreover, a <span class="hlt">wave</span> can be categorized as pulsed or periodic. Most importantly, conditions can be set such that <span class="hlt">waves</span> interfere with one another, resulting in standing <span class="hlt">waves</span>. These have many applications in technology, although they are not always readily identified and/or understood by all students. In this work, we use a simple setup including a low-cost constant spring, such as a Slinky, and the free software Tracker for video analysis. We show they can be very useful for the teaching of mechanical <span class="hlt">wave</span> propagation and the analysis of harmonics in standing <span class="hlt">waves</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18447427','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18447427"><span><span class="hlt">Variational</span> calculation of second-order reduced density matrices by strong N-representability conditions and an <span class="hlt">accurate</span> semidefinite programming solver.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nakata, Maho; Braams, Bastiaan J; Fujisawa, Katsuki; Fukuda, Mituhiro; Percus, Jerome K; Yamashita, Makoto; Zhao, Zhengji</p> <p>2008-04-28</p> <p>The reduced density matrix (RDM) method, which is a <span class="hlt">variational</span> calculation based on the second-order reduced density matrix, is applied to the ground state energies and the dipole moments for 57 different states of atoms, molecules, and to the ground state energies and the elements of 2-RDM for the Hubbard model. We explore the well-known N-representability conditions (P, Q, and G) together with the more recent and much stronger T1 and T2(') conditions. T2(') condition was recently rederived and it implies T2 condition. Using these N-representability conditions, we can usually calculate correlation energies in percentage ranging from 100% to 101%, whose accuracy is similar to CCSD(T) and even better for high spin states or anion systems where CCSD(T) fails. Highly <span class="hlt">accurate</span> calculations are carried out by handling equality constraints and/or developing multiple precision arithmetic in the semidefinite programming (SDP) solver. Results show that handling equality constraints correctly improves the accuracy from 0.1 to 0.6 mhartree. Additionally, improvements by replacing T2 condition with T2(') condition are typically of 0.1-0.5 mhartree. The newly developed multiple precision arithmetic version of SDP solver calculates extraordinary <span class="hlt">accurate</span> energies for the one dimensional Hubbard model and Be atom. It gives at least 16 significant digits for energies, where double precision calculations gives only two to eight digits. It also provides physically meaningful results for the Hubbard model in the high correlation limit.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA.....3381L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA.....3381L"><span><span class="hlt">Accurate</span> determination of the geoid undulation N</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lambrou, E.; Pantazis, G.; Balodimos, D. D.</p> <p>2003-04-01</p> <p>This work is related to the activities of the CERGOP Study Group Geodynamics of the Balkan Peninsula, presents a method for the determination of the <span class="hlt">variation</span> ΔN and, indirectly, of the geoid undulation N with an accuracy of a few millimeters. It is based on the determination of the components xi, eta of the deflection of the vertical using modern geodetic instruments (digital total station and GPS receiver). An analysis of the method is given. Accuracy of the order of 0.01arcsec in the estimated values of the astronomical coordinates Φ and Δ is achieved. The result of applying the proposed method in an area around Athens is presented. In this test application, a system is used which takes advantage of the capabilities of modern geodetic instruments. The GPS receiver permits the determination of the geodetic coordinates at a chosen reference system and, in addition, provides <span class="hlt">accurate</span> timing information. The astronomical observations are performed through a digital total station with electronic registering of angles and time. The required accuracy of the values of the coordinates is achieved in about four hours of fieldwork. In addition, the instrumentation is lightweight, easily transportable and can be setup in the field very quickly. Combined with a stream-lined data reduction procedure and the use of up-to-date astrometric data, the values of the components xi, eta of the deflection of the vertical and, eventually, the changes ΔN of the geoid undulation are determined easily and <span class="hlt">accurately</span>. In conclusion, this work demonstrates that it is quite feasible to create an <span class="hlt">accurate</span> map of the geoid undulation, especially in areas that present large geoid <span class="hlt">variations</span> and other methods are not capable to give <span class="hlt">accurate</span> and reliable results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24487887','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24487887"><span>Single-image-based solution for optics temperature-dependent nonuniformity correction in an uncooled long-<span class="hlt">wave</span> infrared camera.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cao, Yanpeng; Tisse, Christel-Loic</p> <p>2014-02-01</p> <p>In this Letter, we propose an efficient and <span class="hlt">accurate</span> solution to remove temperature-dependent nonuniformity effects introduced by the imaging optics. This single-image-based approach computes optics-related fixed pattern noise (FPN) by fitting the derivatives of correction model to the gradient components, locally computed on an infrared image. A modified bilateral filtering algorithm is applied to local pixel output <span class="hlt">variations</span>, so that the refined gradients are most likely caused by the nonuniformity associated with optics. The estimated bias field is subtracted from the raw infrared imagery to compensate the intensity <span class="hlt">variations</span> caused by optics. The proposed method is fundamentally different from the existing nonuniformity correction (NUC) techniques developed for focal plane arrays (FPAs) and provides an essential image processing functionality to achieve completely shutterless NUC for uncooled long-<span class="hlt">wave</span> infrared (LWIR) imaging systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19...10X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19...10X"><span>On the interaction of small-scale linear <span class="hlt">waves</span> with nonlinear solitary <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xu, Chengzhu; Stastna, Marek</p> <p>2017-04-01</p> <p>In the study of environmental and geophysical fluid flows, linear <span class="hlt">wave</span> theory is well developed and its application has been considered for phenomena of various length and time scales. However, due to the nonlinear nature of fluid flows, in many cases results predicted by linear theory do not agree with observations. One of such cases is internal <span class="hlt">wave</span> dynamics. While small-amplitude <span class="hlt">wave</span> motion may be approximated by linear theory, large amplitude <span class="hlt">waves</span> tend to be solitary-like. In some cases, when the <span class="hlt">wave</span> is highly nonlinear, even weakly nonlinear theories fail to predict the <span class="hlt">wave</span> properties correctly. We study the interaction of small-scale linear <span class="hlt">waves</span> with nonlinear solitary <span class="hlt">waves</span> using highly <span class="hlt">accurate</span> pseudo spectral simulations that begin with a fully nonlinear solitary <span class="hlt">wave</span> and a train of small-amplitude <span class="hlt">waves</span> initialized from linear <span class="hlt">waves</span>. The solitary <span class="hlt">wave</span> then interacts with the linear <span class="hlt">waves</span> through either an overtaking collision or a head-on collision. During the collision, there is a net energy transfer from the linear <span class="hlt">wave</span> train to the solitary <span class="hlt">wave</span>, resulting in an increase in the kinetic energy carried by the solitary <span class="hlt">wave</span> and a phase shift of the solitary <span class="hlt">wave</span> with respect to a freely propagating solitary <span class="hlt">wave</span>. At the same time the linear <span class="hlt">waves</span> are greatly reduced in amplitude. The percentage of energy transferred depends primarily on the wavelength of the linear <span class="hlt">waves</span>. We found that after one full collision cycle, the longest <span class="hlt">waves</span> may retain as much as 90% of the kinetic energy they had initially, while the shortest <span class="hlt">waves</span> lose almost all of their initial energy. We also found that a head-on collision is more efficient in destroying the linear <span class="hlt">waves</span> than an overtaking collision. On the other hand, the initial amplitude of the linear <span class="hlt">waves</span> has very little impact on the percentage of energy that can be transferred to the solitary <span class="hlt">wave</span>. Because of the nonlinearity of the solitary <span class="hlt">wave</span>, these results provide us some insight into <span class="hlt">wave</span>-mean flow</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017APS..DFDD19010S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..DFDD19010S"><span>Wind-<span class="hlt">waves</span> interactions in the Gulf of Eilat</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shani-Zerbib, Almog; Liberzon, Dan; T-SAIL Team</p> <p>2017-11-01</p> <p>The Gulf of Eilat, at the southern tip of Israel, with its elongated rectangular shape and unique diurnal wind pattern is an appealing location for wind-<span class="hlt">waves</span> interactions research. Results of experimental work will be reported analyzing a continuous, 50 hour long, data. Using a combined array of wind and <span class="hlt">waves</span> sensing instruments, the <span class="hlt">wave</span> field statistics and its response to <span class="hlt">variations</span> of wind forcing were investigated. Correlations between diurnal fluctuations in wind magnitude and direction and the <span class="hlt">wave</span> field response will be discussed. The directional spread of <span class="hlt">waves</span>' energy, as estimated by the Wavelet Directional Method, showed a strong response to small <span class="hlt">variations</span> in wind flow direction attributed to the unique topography of the gulf surroundings and its bathymetry. Influenced by relatively strong winds during the light hours, the <span class="hlt">wave</span> field was dominated by a significant amount of breakings that are well pronounced in the saturation range of <span class="hlt">waves</span> spectra. Temporal growth and decay behavior of the <span class="hlt">waves</span> during the morning and evening wind transition periods was examined. Sea state induced roughness, as experienced by the wind flow turbulent boundary layer, is examined in view of the critical layer theory. Israel Science Foundation Grant # 1521/15.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19770032925&hterms=Tidal+waves&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DTidal%2Bwaves','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19770032925&hterms=Tidal+waves&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DTidal%2Bwaves"><span>Internal <span class="hlt">wave</span> observations made with an airborne synthetic aperture imaging radar</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Elachi, C.; Apel, J. R.</p> <p>1976-01-01</p> <p>Synthetic aperture L-band radar flown aboard the NASA CV-990 has observed periodic striations on the ocean surface off the coast of Alaska which have been interpreted as tidally excited oceanic internal <span class="hlt">waves</span> of less than 500 m length. These radar images are compared to photographic imagery of similar <span class="hlt">waves</span> taken from Landsat 1. Both the radar and Landsat images reveal <span class="hlt">variations</span> in reflectivity across each <span class="hlt">wave</span> in a packet that range from low to high to normal. The <span class="hlt">variations</span> point to the simultaneous existence of two mechanisms for the surface signatures of internal <span class="hlt">waves</span>: roughening due to <span class="hlt">wave</span>-current interactions, and smoothing due to slick formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1917132A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1917132A"><span>Wind <span class="hlt">waves</span> climatology of the Southeast Pacific Ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Aguirre, Catalina; Rutllant, José; Falvey, Mark</p> <p>2017-04-01</p> <p>The Southeast Pacific coast still lacks a high-resolution <span class="hlt">wave</span> hindcast and a detailed description of its <span class="hlt">wave</span> climatology. Since buoy <span class="hlt">wave</span> measurements are particularly scarce along the coast of South America, a model hindcast forced with wind information derived from atmospheric Reanalysis seems an attractive way to generate a <span class="hlt">wave</span> climatology in this poorly studied region, providing far better spatial and temporal coverage than can be achieved using observational data alone. Here, the climatology of wind <span class="hlt">waves</span> over the Southeast Pacific is analyzed using a 32-year hindcast from the <span class="hlt">Wave</span>Watch III model, complemented by satellite-derived Significant <span class="hlt">Wave</span> Height (SWH) and buoy measurements for validation. Using partitioned spectral data, a regional climatology of wind sea and swell parameters was constructed. In general, the simulated SWH shows a good agreement with satellite and in-situ SWH measurements. The spatial pattern of SWH is clearly influenced by the meridional <span class="hlt">variation</span> of mean surface wind speed, where the stronger winds over the Southern Ocean play a significant role generating higher <span class="hlt">waves</span> at higher latitudes. Nevertheless, regional features are observed in the annual variability of SWH, which are associated with the existence of atmospheric coastal low-level jets off the coast of Peru and central Chile. In particular, the seasonal <span class="hlt">variation</span> of these synoptic scale jets shows a direct relationship with the annual variability of SWH. Off the coast of Peru at 15°S the coastal low-level jet is strongest during austral winter, increasing the wind sea SWH. In contrast, off central Chile, there is an important increase of wind sea SWH during summer. The seasonal <span class="hlt">variation</span> of the wind sea component leads to a contrasting seasonal <span class="hlt">variation</span> of the total SWH at these locations: off Peru the coastal jet amplifies the annual variability of SWH, while off Central Chile the annual variability of SWH is suppressed by the presence of the coastal jet.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSM51B2440Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM51B2440Y"><span>In situ Observations of Magnetosonic <span class="hlt">Waves</span> Modulated by Background Plasma Density</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yu, X.; Yuan, Z.; Huang, S.; Wang, D.; Funsten, H. O.</p> <p>2017-12-01</p> <p>We report in situ observations by the Van Allen Probe mission that magnetosonic (MS) <span class="hlt">waves</span> are clearly relevant to appear relevant to the background plasma number density. As the satellite moved across dense and tenuous plasma alternatively, MS <span class="hlt">waves</span> occurred only in lower density region. As the observed protons with 'ring' distributions provide free energy, local linear growth rates are calculated and show that magnetosonic <span class="hlt">waves</span> can be locally excited in tenuous plasma. With <span class="hlt">variations</span> of the background plasma density, the temporal <span class="hlt">variations</span> of local <span class="hlt">wave</span> growth rates calculated with the observed proton ring distributions, show a remarkable agreement with those of the observed <span class="hlt">wave</span> amplitude. Therefore, the paper provides a direct proof that background plasma densities can modulate the amplitudes of magnetosonic <span class="hlt">waves</span> through controlling the <span class="hlt">wave</span> growth rates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920033133&hterms=hinson&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D40%26Ntt%3Dhinson','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920033133&hterms=hinson&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D40%26Ntt%3Dhinson"><span>Equatorial <span class="hlt">waves</span> in the stratosphere of Uranus</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hinson, David P.; Magalhaes, Julio A.</p> <p>1991-01-01</p> <p>Analyses of radio occultation data from Voyager 2 have led to the discovery and characterization of an equatorial <span class="hlt">wave</span> in the Uranus stratosphere. The observed quasi-periodic vertical atmospheric density <span class="hlt">variations</span> are in close agreement with theoretical predictions for a <span class="hlt">wave</span> that propagates vertically through the observed background structure of the stratosphere. Quantitative comparisons between measurements obtained at immersion and at emersion yielded constraints on the meridional and zonal structure of the <span class="hlt">wave</span>; the fact that the two sets of measurements are correlated suggests a <span class="hlt">wave</span> of planetary scale. Two equatorial <span class="hlt">wave</span> models are proposed for the <span class="hlt">wave</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014E%26ES...22c2037L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014E%26ES...22c2037L"><span>Experimental investigation of the local <span class="hlt">wave</span> speed in a draft tube with cavitation vortex rope</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Landry, C.; Favrel, A.; Müller, A.; Nicolet, C.; Yamamoto, K.; Avellan, F.</p> <p>2014-03-01</p> <p>Hydraulic machines operating in a wider range are subjected to cavitation developments inducing undesirable pressure pulsations which could lead to potential instability of the power plant. The occurrence of pulsating cavitation volumes in the runner and the draft tube is considered as a mass source of the system and is depending on the cavitation compliance. This dynamic parameter represents the cavitation volume <span class="hlt">variation</span> with the respect to a <span class="hlt">variation</span> of pressure and defines implicitly the local <span class="hlt">wave</span> speed in the draft tube. This parameter is also decisive for an <span class="hlt">accurate</span> prediction of system eigen frequencies. Therefore, the local <span class="hlt">wave</span> speed in the draft tube is intrinsically linked to the eigen frequencies of the hydraulic system. Thus, if the natural frequency of a hydraulic system can be determined experimentally, it also becomes possible to estimate a local <span class="hlt">wave</span> speed in the draft tube with a numerical model. In the present study, the reduced scale model of a Francis turbine (v=0.29) was investigated at off-design conditions. In order to measure the first eigenmode of the hydraulic test rig, an additional discharge was injected at the inlet of the hydraulic turbine at a variable frequency and amplitude to excite the system. Thus, with different pressure sensors installed on the test rig, the first eigenmode was determined. Then, a hydro-acoustic test rig model was developed with the In-house EPFL SIMSEN software and the local <span class="hlt">wave</span> speed in the draft tube was adjusted to obtain the same first eigen frequency as that measured experimentally. Finally, this method was applied for different Thoma and Froude numbers at part load conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018GeoJI.tmp..223P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018GeoJI.tmp..223P"><span><span class="hlt">Wave</span> propagation modelling of induced earthquakes at the Groningen gas production site</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Paap, Bob; Kraaijpoel, Dirk; Bakker, Marcel; Gharti, Hom Nath</p> <p>2018-06-01</p> <p>Gas extraction from the Groningen natural gas field, situated in the Netherlands, frequently induces earthquakes in the reservoir that cause damage to buildings and pose a safety hazard and a nuisance to the local population. Due to the dependence of the national heating infrastructure on Groningen gas, the short-term mitigation measures are mostly limited to a combination of spatiotemporal redistribution of gas production and strengthening measures for buildings. All options become more effective with a better understanding of both source processes and seismic <span class="hlt">wave</span> propagation. Detailed <span class="hlt">wave</span> propagation simulations improve both the inference of source processes from observed ground motions and the forecast of ground motions as input for hazard studies and seismic network design. The velocity structure at the Groningen site is relatively complex, including both deep high-velocity and shallow low-velocity deposits showing significant thickness <span class="hlt">variations</span> over relatively small spatial extents. We performed a detailed three-dimensional <span class="hlt">wave</span> propagation modelling study for an induced earthquake in the Groningen natural gas field using the spectral-element method. We considered an earthquake that nucleated along a normal fault with local magnitude of {{{M}}_{{L}}} = 3. We created a dense mesh with element size varying from 12 to 96 m, and used a source frequency of 7 Hz, such that frequencies generated during the simulation were <span class="hlt">accurately</span> sampled up to 10 Hz. The velocity/density model is constructed using a three-dimensional geological model of the area, including both deep high-velocity salt deposits overlying the source region and shallow low-velocity sediments present in a deep but narrow tunnel valley. The results show that the three-dimensional density/velocity model in the Groningen area clearly play a large role in the <span class="hlt">wave</span> propagation and resulting surface ground motions. The 3d structure results in significant lateral <span class="hlt">variations</span> in site response. The high</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26873972','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26873972"><span>Novel <span class="hlt">wave</span> power analysis linking pressure-flow <span class="hlt">waves</span>, <span class="hlt">wave</span> potential, and the forward and backward components of hydraulic power.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mynard, Jonathan P; Smolich, Joseph J</p> <p>2016-04-15</p> <p><span class="hlt">Wave</span> intensity analysis provides detailed insights into factors influencing hemodynamics. However, <span class="hlt">wave</span> intensity is not a conserved quantity, so it is sensitive to diameter <span class="hlt">variations</span> and is not distributed among branches of a junction. Moreover, the fundamental relation between <span class="hlt">waves</span> and hydraulic power is unclear. We, therefore, propose an alternative to <span class="hlt">wave</span> intensity called "<span class="hlt">wave</span> power," calculated via incremental changes in pressure and flow (dPdQ) and a novel time-domain separation of hydraulic pressure power and kinetic power into forward and backward <span class="hlt">wave</span>-related components (ΠP±and ΠQ±). <span class="hlt">Wave</span> power has several useful properties:1) it is obtained directly from flow measurements, without requiring further calculation of velocity;2) it is a quasi-conserved quantity that may be used to study the relative distribution of <span class="hlt">waves</span> at junctions; and3) it has the units of power (Watts). We also uncover a simple relationship between <span class="hlt">wave</span> power and changes in ΠP±and show that <span class="hlt">wave</span> reflection reduces transmitted power. Absolute values of ΠP±represent <span class="hlt">wave</span> potential, a recently introduced concept that unifies steady and pulsatile aspects of hemodynamics. We show that <span class="hlt">wave</span> potential represents the hydraulic energy potential stored in a compliant pressurized vessel, with spatial gradients producing <span class="hlt">waves</span> that transfer this energy. These techniques and principles are verified numerically and also experimentally with pressure/flow measurements in all branches of a central bifurcation in sheep, under a wide range of hemodynamic conditions. The proposed "<span class="hlt">wave</span> power analysis," encompassing <span class="hlt">wave</span> power, <span class="hlt">wave</span> potential, and <span class="hlt">wave</span> separation of hydraulic power provides a potent time-domain approach for analyzing hemodynamics. Copyright © 2016 the American Physiological Society.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22311311-rotation-induced-nonlinear-wavepackets-internal-waves','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22311311-rotation-induced-nonlinear-wavepackets-internal-waves"><span>Rotation-induced nonlinear wavepackets in internal <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Whitfield, A. J., E-mail: ashley.whitfield.12@ucl.ac.uk; Johnson, E. R., E-mail: e.johnson@ucl.ac.uk</p> <p>2014-05-15</p> <p>The long time effect of weak rotation on an internal solitary <span class="hlt">wave</span> is the decay into inertia-gravity <span class="hlt">waves</span> and the eventual formation of a localised wavepacket. Here this initial value problem is considered within the context of the Ostrovsky, or the rotation-modified Korteweg-de Vries (KdV), equation and a numerical method for obtaining <span class="hlt">accurate</span> wavepacket solutions is presented. The flow evolutions are described in the regimes of relatively-strong and relatively-weak rotational effects. When rotational effects are relatively strong a second-order soliton solution of the nonlinear Schrödinger equation <span class="hlt">accurately</span> predicts the shape, and phase and group velocities of the numerically determined wavepackets.more » It is suggested that these solitons may form from a local Benjamin-Feir instability in the inertia-gravity <span class="hlt">wave</span>-train radiated when a KdV solitary <span class="hlt">wave</span> rapidly adjusts to the presence of strong rotation. When rotational effects are relatively weak the initial KdV solitary <span class="hlt">wave</span> remains coherent longer, decaying only slowly due to weak radiation and modulational instability is no longer relevant. Wavepacket solutions in this regime appear to consist of a modulated KdV soliton wavetrain propagating on a slowly varying background of finite extent.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DFDA14001Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFDA14001Z"><span>Experimental study of temporal evolution of <span class="hlt">waves</span> under transient wind conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zavadsky, Andrey; Shemer, Lev</p> <p>2016-11-01</p> <p>Temporal <span class="hlt">variation</span> of the <span class="hlt">waves</span> excited by nearly sudden wind forcing over an initially still water surface is studied in a small wind-<span class="hlt">wave</span> flume at Tel Aviv University for variety of fetches and wind velocities. Simultaneous measurements of the surface elevation using a conventional capacitance <span class="hlt">wave</span>-gauge and of the surface slope in along-wind and cross-wind directions by a laser slope gauge were performed. <span class="hlt">Variation</span> with time of two components of instantaneous surface velocity was measured by particle tracking velocimetry. The size of the experimental facility and thus relatively short characteristic time scales of the phenomena under investigation, as well as an automated experimental procedure controlling the experiments made it possible to record a large amount of independent realizations for each wind-fetch condition. Sufficient data were accumulated to compute reliable ensemble averaged temporal <span class="hlt">variation</span> of governing <span class="hlt">wave</span> parameters. The essentially three-dimensional structure of wind-<span class="hlt">waves</span> at all stages of evolution is demonstrated. The results obtained at each wind-fetch condition allowed to characterize the major stages of the evolution of the wind-<span class="hlt">wave</span> field and to suggest a plausible scenario for the initial growth of the wind-<span class="hlt">waves</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ThCFD.tmp....5D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ThCFD.tmp....5D"><span>Solitary <span class="hlt">wave</span> solutions and their interactions for fully nonlinear water <span class="hlt">waves</span> with surface tension in the generalized Serre equations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dutykh, Denys; Hoefer, Mark; Mitsotakis, Dimitrios</p> <p>2018-04-01</p> <p>Some effects of surface tension on fully nonlinear, long, surface water <span class="hlt">waves</span> are studied by numerical means. The differences between various solitary <span class="hlt">waves</span> and their interactions in subcritical and supercritical surface tension regimes are presented. Analytical expressions for new peaked traveling <span class="hlt">wave</span> solutions are presented in the dispersionless case of critical surface tension. Numerical experiments are performed using a high-<span class="hlt">accurate</span> finite element method based on smooth cubic splines and the four-stage, classical, explicit Runge-Kutta method of order 4.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920016037','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920016037"><span>Study and interpretation of the millimeter-<span class="hlt">wave</span> spectrum of Venus</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fahd, Antoine K.; Steffes, Paul G.</p> <p>1992-01-01</p> <p>The effects of the Venus atmospheric constituents on its millimeter wavelength emission are investigated. Specifically, this research describes the methodology and the results of laboratory measurements which are used to calculate the opacity of some of the major absorbers in the Venus atmosphere. The pressure broadened absorption of gaseous SO2/CO2 and gaseous H2SO4/CO2 has been measured at millimeter wavelengths. We have also developed new formalisms for computing the absorptivities of these gases based on our laboratory work. The complex dielectric constant of liquid sulfuric acid has been measured and the expected opacity from the liquid sulfuric acid cloud layer found in the atmosphere of Venus has been evaluated. The partial pressure of gaseous H2SO4 has been measured which results in a more <span class="hlt">accurate</span> estimate of the dissociation factor of H2SO4. A radiative transfer model has been developed in order to understand how each atmospheric constituent affects the millimeter <span class="hlt">wave</span> emissions from Venus. Our results from the radiative transfer model are compared with recent observations of the micro-<span class="hlt">wave</span> and millimeter <span class="hlt">wave</span> emissions from Venus. Our main conclusion from this work is that gaseous H2SO4 is the most likely cause of the <span class="hlt">variation</span> in the observed emission from Venus at 112 GHz.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1221548','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1221548"><span>Generalized multiscale finite-element method (GMsFEM) for elastic <span class="hlt">wave</span> propagation in heterogeneous, anisotropic media</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Gao, Kai; Fu, Shubin; Gibson, Richard L.</p> <p></p> <p>It is important to develop fast yet <span class="hlt">accurate</span> numerical methods for seismic <span class="hlt">wave</span> propagation to characterize complex geological structures and oil and gas reservoirs. However, the computational cost of conventional numerical modeling methods, such as finite-difference method and finite-element method, becomes prohibitively expensive when applied to very large models. We propose a Generalized Multiscale Finite-Element Method (GMsFEM) for elastic <span class="hlt">wave</span> propagation in heterogeneous, anisotropic media, where we construct basis functions from multiple local problems for both the boundaries and interior of a coarse node support or coarse element. The application of multiscale basis functions can capture the fine scale mediummore » property <span class="hlt">variations</span>, and allows us to greatly reduce the degrees of freedom that are required to implement the modeling compared with conventional finite-element method for <span class="hlt">wave</span> equation, while restricting the error to low values. We formulate the continuous Galerkin and discontinuous Galerkin formulation of the multiscale method, both of which have pros and cons. Applications of the multiscale method to three heterogeneous models show that our multiscale method can effectively model the elastic <span class="hlt">wave</span> propagation in anisotropic media with a significant reduction in the degrees of freedom in the modeling system.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22465640-generalized-multiscale-finite-element-method-gmsfem-elastic-wave-propagation-heterogeneous-anisotropic-media','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22465640-generalized-multiscale-finite-element-method-gmsfem-elastic-wave-propagation-heterogeneous-anisotropic-media"><span>Generalized Multiscale Finite-Element Method (GMsFEM) for elastic <span class="hlt">wave</span> propagation in heterogeneous, anisotropic media</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Gao, Kai, E-mail: kaigao87@gmail.com; Fu, Shubin, E-mail: shubinfu89@gmail.com; Gibson, Richard L., E-mail: gibson@tamu.edu</p> <p></p> <p>It is important to develop fast yet <span class="hlt">accurate</span> numerical methods for seismic <span class="hlt">wave</span> propagation to characterize complex geological structures and oil and gas reservoirs. However, the computational cost of conventional numerical modeling methods, such as finite-difference method and finite-element method, becomes prohibitively expensive when applied to very large models. We propose a Generalized Multiscale Finite-Element Method (GMsFEM) for elastic <span class="hlt">wave</span> propagation in heterogeneous, anisotropic media, where we construct basis functions from multiple local problems for both the boundaries and interior of a coarse node support or coarse element. The application of multiscale basis functions can capture the fine scale mediummore » property <span class="hlt">variations</span>, and allows us to greatly reduce the degrees of freedom that are required to implement the modeling compared with conventional finite-element method for <span class="hlt">wave</span> equation, while restricting the error to low values. We formulate the continuous Galerkin and discontinuous Galerkin formulation of the multiscale method, both of which have pros and cons. Applications of the multiscale method to three heterogeneous models show that our multiscale method can effectively model the elastic <span class="hlt">wave</span> propagation in anisotropic media with a significant reduction in the degrees of freedom in the modeling system.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1221548-generalized-multiscale-finite-element-method-gmsfem-elastic-wave-propagation-heterogeneous-anisotropic-media','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1221548-generalized-multiscale-finite-element-method-gmsfem-elastic-wave-propagation-heterogeneous-anisotropic-media"><span>Generalized multiscale finite-element method (GMsFEM) for elastic <span class="hlt">wave</span> propagation in heterogeneous, anisotropic media</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Gao, Kai; Fu, Shubin; Gibson, Richard L.; ...</p> <p>2015-04-14</p> <p>It is important to develop fast yet <span class="hlt">accurate</span> numerical methods for seismic <span class="hlt">wave</span> propagation to characterize complex geological structures and oil and gas reservoirs. However, the computational cost of conventional numerical modeling methods, such as finite-difference method and finite-element method, becomes prohibitively expensive when applied to very large models. We propose a Generalized Multiscale Finite-Element Method (GMsFEM) for elastic <span class="hlt">wave</span> propagation in heterogeneous, anisotropic media, where we construct basis functions from multiple local problems for both the boundaries and interior of a coarse node support or coarse element. The application of multiscale basis functions can capture the fine scale mediummore » property <span class="hlt">variations</span>, and allows us to greatly reduce the degrees of freedom that are required to implement the modeling compared with conventional finite-element method for <span class="hlt">wave</span> equation, while restricting the error to low values. We formulate the continuous Galerkin and discontinuous Galerkin formulation of the multiscale method, both of which have pros and cons. Applications of the multiscale method to three heterogeneous models show that our multiscale method can effectively model the elastic <span class="hlt">wave</span> propagation in anisotropic media with a significant reduction in the degrees of freedom in the modeling system.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1262235-numerical-modeling-effects-wave-energy-converter-characteristics-nearshore-wave-conditions','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1262235-numerical-modeling-effects-wave-energy-converter-characteristics-nearshore-wave-conditions"><span>Numerical modeling of the effects of <span class="hlt">wave</span> energy converter characteristics on nearshore <span class="hlt">wave</span> conditions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Chang, G.; Ruehl, K.; Jones, C. A.; ...</p> <p>2015-12-24</p> <p>Modeled nearshore <span class="hlt">wave</span> propagation was investigated downstream of simulated <span class="hlt">wave</span> energy converters (WECs) to evaluate overall near- and far-field effects of WEC arrays. Model sensitivity to WEC characteristics and WEC array deployment scenarios was evaluated using a modified version of an industry standard <span class="hlt">wave</span> model, Simulating <span class="hlt">WAves</span> Nearshore (SWAN), which allows the incorporation of device-specific WEC characteristics to specify obstacle transmission. The sensitivity study illustrated that WEC device type and subsequently its size directly resulted in <span class="hlt">wave</span> height <span class="hlt">variations</span> in the lee of the WEC array. <span class="hlt">Wave</span> heights decreased up to 30% between modeled scenarios with and without WECs formore » large arrays (100 devices) of relatively sizable devices (26 m in diameter) with peak power generation near to the modeled incident <span class="hlt">wave</span> height. Other WEC types resulted in less than 15% differences in modeled <span class="hlt">wave</span> height with and without WECs, with lesser influence for WECs less than 10 m in diameter. <span class="hlt">Wave</span> directions and periods were largely insensitive to changes in parameters. Furthermore, additional model parameterization and analysis are required to fully explore the model sensitivity of peak <span class="hlt">wave</span> period and mean <span class="hlt">wave</span> direction to the varying of the parameters.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3777432','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3777432"><span>A k-Space Method for Moderately Nonlinear <span class="hlt">Wave</span> Propagation</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Jing, Yun; Wang, Tianren; Clement, Greg T.</p> <p>2013-01-01</p> <p>A k-space method for moderately nonlinear <span class="hlt">wave</span> propagation in absorptive media is presented. The Westervelt equation is first transferred into k-space via Fourier transformation, and is solved by a modified <span class="hlt">wave</span>-vector time-domain scheme. The present approach is not limited to forward propagation or parabolic approximation. One- and two-dimensional problems are investigated to verify the method by comparing results to analytic solutions and finite-difference time-domain (FDTD) method. It is found that to obtain <span class="hlt">accurate</span> results in homogeneous media, the grid size can be as little as two points per wavelength, and for a moderately nonlinear problem, the Courant–Friedrichs–Lewy number can be as large as 0.4. Through comparisons with the conventional FDTD method, the k-space method for nonlinear <span class="hlt">wave</span> propagation is shown here to be computationally more efficient and <span class="hlt">accurate</span>. The k-space method is then employed to study three-dimensional nonlinear <span class="hlt">wave</span> propagation through the skull, which shows that a relatively <span class="hlt">accurate</span> focusing can be achieved in the brain at a high frequency by sending a low frequency from the transducer. Finally, implementations of the k-space method using a single graphics processing unit shows that it required about one-seventh the computation time of a single-core CPU calculation. PMID:22899114</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..122.8770T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..122.8770T"><span>Sixteen year <span class="hlt">variation</span> of horizontal phase velocity and propagation direction of mesospheric and thermospheric <span class="hlt">waves</span> in airglow images at Shigaraki, Japan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Takeo, D.; Shiokawa, K.; Fujinami, H.; Otsuka, Y.; Matsuda, T. S.; Ejiri, M. K.; Nakamura, T.; Yamamoto, M.</p> <p>2017-08-01</p> <p>We analyzed the horizontal phase velocity of gravity <span class="hlt">waves</span> and medium-scale traveling ionospheric disturbances (MSTIDs) by using the three-dimensional fast Fourier transform method developed by Matsuda et al. (2014) for 557.7 nm (altitude: 90-100 km) and 630.0 nm (altitude: 200-300 km) airglow images obtained at Shigaraki MU Observatory (34.8°N, 136.1°E, dip angle: 49°) over ˜16 years from 16 March 1999 to 20 February 2015. The analysis of 557.7 nm airglow images shows clear seasonal <span class="hlt">variation</span> of the propagation direction of gravity <span class="hlt">waves</span> in the mesopause region. In spring, summer, fall, and winter, the peak directions are northeastward, northeastward, northwestward, and southwestward, respectively. The difference in east-west propagation direction between summer and winter is probably caused by the wind filtering effect due to the zonal mesospheric jet. Comparison with tropospheric reanalysis data shows that the difference in north-south propagation direction between summer and winter is caused by differences in the latitudinal location of <span class="hlt">wave</span> sources due to convective activity in the troposphere relative to Shigaraki. The analysis of 630.0 nm airglow images shows that the propagation direction of MSTIDs is mainly southwestward with a minor northeastward component throughout the 16 years. A clear negative correlation is seen between the yearly power spectral density of MSTIDs and F10.7 solar flux. This negative correlation with solar activity may be explained by the linear growth rate of the Perkins instability and secondary <span class="hlt">wave</span> generation of gravity <span class="hlt">waves</span> in the thermosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19840065462&hterms=Legendre+polynomials&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DLegendre%2Bpolynomials','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19840065462&hterms=Legendre+polynomials&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DLegendre%2Bpolynomials"><span>Thermospheric gravity <span class="hlt">waves</span> near the source - Comparison of <span class="hlt">variations</span> in neutral temperature and vertical velocity at Sondre Stromfjord</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Herrero, F. A.; Mayr, H. G.; Harris, I.; Varosi, F.; Meriwether, J. W., Jr.</p> <p>1984-01-01</p> <p>Theoretical predictions of thermospheric gravity <span class="hlt">wave</span> oscillations are compared with observed neutral temperatures and velocities. The data were taken in February 1983 using a Fabry-Perot interferometer located on Greenland, close to impulse heat sources in the auroral oval. The phenomenon was modeled in terms of linearized equations of motion of the atmosphere on a slowly rotating sphere. Legendre polynomials were used as eigenfunctions and the transfer function amplitude surface was characterized by maxima in the wavenumber frequency plane. Good agreement for predicted and observed velocities and temperatures was attained in the 250-300 km altitude. The amplitude of the vertical velocity, however, was not <span class="hlt">accurately</span> predicted, nor was the temperature variability. The vertical velocity did exhibit maxima and minima in response to corresponding temperature changes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1984GeoRL..11..939H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1984GeoRL..11..939H"><span>Thermospheric gravity <span class="hlt">waves</span> near the source - Comparison of <span class="hlt">variations</span> in neutral temperature and vertical velocity at Sondre Stromfjord</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Herrero, F. A.; Mayr, H. G.; Harris, I.; Varosi, F.; Meriwether, J. W., Jr.</p> <p>1984-09-01</p> <p>Theoretical predictions of thermospheric gravity <span class="hlt">wave</span> oscillations are compared with observed neutral temperatures and velocities. The data were taken in February 1983 using a Fabry-Perot interferometer located on Greenland, close to impulse heat sources in the auroral oval. The phenomenon was modeled in terms of linearized equations of motion of the atmosphere on a slowly rotating sphere. Legendre polynomials were used as eigenfunctions and the transfer function amplitude surface was characterized by maxima in the wavenumber frequency plane. Good agreement for predicted and observed velocities and temperatures was attained in the 250-300 km altitude. The amplitude of the vertical velocity, however, was not <span class="hlt">accurately</span> predicted, nor was the temperature variability. The vertical velocity did exhibit maxima and minima in response to corresponding temperature changes.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017Geomo.280...76H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017Geomo.280...76H"><span>The effect of wind <span class="hlt">waves</span> on spring-neap <span class="hlt">variations</span> in sediment transport in two meso-tidal estuarine basins with contrasting fetch</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hunt, Stephen; Bryan, Karin R.; Mullarney, Julia C.</p> <p>2017-03-01</p> <p>Higher-energy episodic wind-<span class="hlt">waves</span> can substantially modify estuarine morphology over short timescales which are superimposed on lower-energy but long-term tidal asymmetry effects. Theoretically, wind <span class="hlt">waves</span> and tidal currents change the morphology through their combined influence on the asymmetry between bed shear stress, τmax, on the flood and ebb tide, although the relative contribution of such wind-<span class="hlt">wave</span> events in shaping the long-term morphological evolution in real estuaries is not well known. If the rising tide reaches sufficiently high water depths, τmax decreases as water depth increases because of the depth attenuation of <span class="hlt">wave</span> orbital velocities. However, this effect is opposed by the increase in τmax associated with the longer fetch occurring at high tide, which allows the generation of larger <span class="hlt">waves</span>. Additionally, these effects are superimposed on the spring-neap <span class="hlt">variations</span> in current associated with changes to tidal range. By comparing two mesotidal basins in the same dendritic estuary, one with a large fetch aligned with the prevailing wind direction and one with only a small fetch, we show that for a sufficiently large fetch even the small and frequently occurring wind events are able to create <span class="hlt">waves</span> that are capable of changing the morphology ('morphologically significant'). Conversely, in the basin with reduced fetch, these <span class="hlt">waves</span> are generated less frequently and therefore are of reduced morphological significance. Here, we find that although tidal current should be stronger during spring tides and alter morphology more, on average the reduced fetch and increased water depth during spring tides mean that the basin-averaged intertidal τmax is similar during both spring and neap tides. Moreover, in the presence of wind <span class="hlt">waves</span>, the duration of slack water is reduced during neap tides relative to spring tides, resulting in a reduced chance for accretion during neap tides. Finally, τmax is lower in the subtidal channels during neaps than springs but of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70193648','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70193648"><span>Non-perturbational surface-<span class="hlt">wave</span> inversion: A Dix-type relation for surface <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Haney, Matt; Tsai, Victor C.</p> <p>2015-01-01</p> <p>We extend the approach underlying the well-known Dix equation in reflection seismology to surface <span class="hlt">waves</span>. Within the context of surface <span class="hlt">wave</span> inversion, the Dix-type relation we derive for surface <span class="hlt">waves</span> allows <span class="hlt">accurate</span> depth profiles of shear-<span class="hlt">wave</span> velocity to be constructed directly from phase velocity data, in contrast to perturbational methods. The depth profiles can subsequently be used as an initial model for nonlinear inversion. We provide examples of the Dix-type relation for under-parameterized and over-parameterized cases. In the under-parameterized case, we use the theory to estimate crustal thickness, crustal shear-<span class="hlt">wave</span> velocity, and mantle shear-<span class="hlt">wave</span> velocity across the Western U.S. from phase velocity maps measured at 8-, 20-, and 40-s periods. By adopting a thin-layer formalism and an over-parameterized model, we show how a regularized inversion based on the Dix-type relation yields smooth depth profiles of shear-<span class="hlt">wave</span> velocity. In the process, we quantitatively demonstrate the depth sensitivity of surface-<span class="hlt">wave</span> phase velocity as a function of frequency and the accuracy of the Dix-type relation. We apply the over-parameterized approach to a near-surface data set within the frequency band from 5 to 40 Hz and find overall agreement between the inverted model and the result of full nonlinear inversion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.4308K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.4308K"><span>Momentum flux of convective gravity <span class="hlt">waves</span> derived from an off-line gravity <span class="hlt">wave</span> parameterization: Spatiotemporal <span class="hlt">variations</span> at source level</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kang, Min-Jee; Chun, Hye-Yeong; Kim, Young-Ha</p> <p>2017-04-01</p> <p>Spatiotemporal <span class="hlt">variations</span> in momentum flux spectra of convective gravity <span class="hlt">waves</span> (CGWs) at the source level (cloud top), including nonlinear forcing effects, are examined using an off-line version of CGW parameterization and global reanalysis data. We used 1-hourly NCEP Climate Forecast System Reanalysis (CFSR) forecast data for a period of 32 years (1979-2010), with a horizontal resolution of 1° x1°. The cloud-top momentum flux (CTMF) is not solely proportional to the convective heating rate but is affected by the <span class="hlt">wave</span>-filtering and resonance factor (WFRF), background stability and temperature underlying the convection. Consequently, the primary peak of CTMF is in the winter hemisphere midlatitude in association with storm-track region where secondary peak of convective heating exists, whereas the secondary peak of CTMF appears in the summer hemisphere tropics and intertropical convergence zone (ITCZ), where primary peak of convective heating exists. The magnitude of CTMF fluctuates largely with 1 year and 1 day periods, commonly in major CTMF regions. At low latitudes and Pacific storm track region, a 6-month period is also significant, and the decadal cycle appears in the Asian summer monsoon region and the Andes Mountains. The equatorial eastern Pacific region exhibits substantial inter-annual to decadal scale of variability with decreasing trend that is described as statistically significant. Interestingly, the correlation between convective heating and the CTMF is relatively lower in the equatorial region than in other regions. The CTMF spectra in the large-CTMF regions reveal that the spectrum shape and width changes with season and location, along with anisotropic shape of the CTMF spectrum, caused by changes in wind speed at the cloud top and the moving speed of convection. The CTMF in the 10°N to 10°S during the period of February to May 2010, when the PreConcordiasi campaign held, approximately follows a lognormal distribution but with a slight</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003DPS....35.4803G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003DPS....35.4803G"><span><span class="hlt">Wave</span>-clouds coupling in the Jovian troposphere.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gaulme, P.; Mosser, B.</p> <p>2003-05-01</p> <p>First studies about Jovian oscillations are due to Vorontsov et al. (1976). Attempts to observe them started in the late 1980's (Deming et al. 1989, Mosser et al. 1991). The micro-satellite Jovis and ground-based observations campaign such as SŸMPA (e.g Baglin et al. 1999) account for an <span class="hlt">accurate</span> analysis of the cloud response to an acoustic <span class="hlt">wave</span>. Therefore, the propagation of sound or gravity <span class="hlt">waves</span> in the Jovian troposphere is revisited, in order to estimate their effect on the highest clouds layer. From basic thermodynamics, the troposphere should be stratified in three major ice clouds layers: water-ammonia, ammonium-hydrosulfide and ammonia ice for the highest. The presence of ammonia ice clouds has been inferred from Kuiper in 1952, and was predicted to dominate the Jovian skies. However, they had been observed spectroscopically over less than one percent of the surface. This absence of spectral proof could come from a coating of ammonia particles from other substances (Baines et al. 2002). In this work, we study the behaviour of a cloud submitted to a periodic pressure perturbation. We suppose a vertical <span class="hlt">wave</span> propagating in a plane parallel atmosphere including an ammonia ice cloud layer. We determine the relation between the Lagrangian pressure perturbation and the <span class="hlt">variation</span> of the fraction of solid ammonia. The linearized equations governing the evolution of the Eulerian pressure and density perturbed terms allows us to study how the propagation is altered by the clouds and how the clouds move with the <span class="hlt">wave</span>. Finally, because a pressure perturbation modifies the fraction of solid ammonia, we estimate how much an ammonia crystal should grow or decrease and how the clouds albedo could change with the <span class="hlt">wave</span>. Baglin et al. 1999. BAAS 31, 813. Baines et al. 2002. Icarus 159, 74. Deming et al. 1989. Icarus 21, 943. Kuiper 1952.The atmospheres of the Earth and Planets pp. 306-405. Univ. of Chicago Press, Chicago. Mosser et al. 1991. A&A 251, 356. Vorontsov et al</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/2014/1264/pdf/ofr2014-1264.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/2014/1264/pdf/ofr2014-1264.pdf"><span>Shear-<span class="hlt">wave</span> velocity and site-amplification factors for 50 Australian sites determined by the spectral analysis of surface <span class="hlt">waves</span> method</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Kayen, Robert E.; Carkin, Bradley A.; Allen, Trevor; Collins, Clive; McPherson, Andrew; Minasian, Diane L.</p> <p>2015-01-01</p> <p>One-dimensional shear-<span class="hlt">wave</span> velocity (VS ) profiles are presented at 50 strong motion sites in New South Wales and Victoria, Australia. The VS profiles are estimated with the spectral analysis of surface <span class="hlt">waves</span> (SASW) method. The SASW method is a noninvasive method that indirectly estimates the VS at depth from <span class="hlt">variations</span> in the Rayleigh <span class="hlt">wave</span> phase velocity at the surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JCoPh.365..350W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JCoPh.365..350W"><span>A highly <span class="hlt">accurate</span> finite-difference method with minimum dispersion error for solving the Helmholtz equation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, Zedong; Alkhalifah, Tariq</p> <p>2018-07-01</p> <p>Numerical simulation of the acoustic <span class="hlt">wave</span> equation in either isotropic or anisotropic media is crucial to seismic modeling, imaging and inversion. Actually, it represents the core computation cost of these highly advanced seismic processing methods. However, the conventional finite-difference method suffers from severe numerical dispersion errors and S-<span class="hlt">wave</span> artifacts when solving the acoustic <span class="hlt">wave</span> equation for anisotropic media. We propose a method to obtain the finite-difference coefficients by comparing its numerical dispersion with the exact form. We find the optimal finite difference coefficients that share the dispersion characteristics of the exact equation with minimal dispersion error. The method is extended to solve the acoustic <span class="hlt">wave</span> equation in transversely isotropic (TI) media without S-<span class="hlt">wave</span> artifacts. Numerical examples show that the method is highly <span class="hlt">accurate</span> and efficient.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19900018887','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19900018887"><span>The 27-day versus 13.5-day <span class="hlt">variations</span> in the solar Lyman-alpha radiation and the radio <span class="hlt">wave</span> absorption in the lower ionosphere over Europe</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Delamorena, B. A.; Lastovicka, Jan; Rapoport, Z. TS.; Alberca, L.</p> <p>1989-01-01</p> <p>In order to clarify the question of solar periods in absorption, the pattern was studied of the solar Lyman-alpha radiation (the principal ionizing agent of the lower ionosphere) and of the radio <span class="hlt">wave</span> absorption at five widely spaced places in Europe. When the solar Lyman-alpha flux variability is very well developed, then it dominates in the lower ionospheric variability. The most pronounced Lyman-alpha <span class="hlt">variation</span> on time scale day-month is the solar rotation <span class="hlt">variation</span> (about 27 days). When the Lyman-alpha variability is developed rather poorly, as it is typical for periods dominated by the 13.5 day variability, then the lower ionospheric variability appears to be dominated by <span class="hlt">variations</span> of meteorological origin. The conclusions hold for all five widely spaced placed in Europe.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19960011387','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19960011387"><span>Novel high-gain, improved-bandwidth, finned-ladder V-band Traveling-<span class="hlt">Wave</span> Tube slow-<span class="hlt">wave</span> circuit design</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kory, Carol L.; Wilson, Jeffrey D.</p> <p>1994-01-01</p> <p>The V-band frequency range of 59-64 GHz is a region of the millimeter-<span class="hlt">wave</span> spectrum that has been designated for inter-satellite communications. As a first effort to develop a high-efficiency V-band Traveling-<span class="hlt">Wave</span> Tube (TWT), <span class="hlt">variations</span> on a ring-plane slow-<span class="hlt">wave</span> circuit were computationally investigated to develop an alternative to the more conventional ferruled coupled-cavity circuit. The ring-plane circuit was chosen because of its high interaction impedance, large beam aperture, and excellent thermal dissipation properties. Despite these advantages, however, low bandwidth and high voltage requirements have, until now, prevented its acceptance outside the laboratory. In this paper, the three-dimensional electrodynamic simulation code MAFIA (solution of MAxwell's Equation by the Finite-Integration-Algorithm) is used to investigate methods of increasing the bandwidth and lowering the operating voltage of the ring-plane circuit. Calculations of frequency-phase dispersion, beam on-axis interaction impedance, attenuation and small-signal gain per wavelength were performed for various geometric <span class="hlt">variations</span> and loading distributions of the ring-plane TWT slow-<span class="hlt">wave</span> circuit. Based on the results of the <span class="hlt">variations</span>, a circuit termed the finned-ladder TWT slow-<span class="hlt">wave</span> circuit was designed and is compared here to the scaled prototype ring-plane and a conventional ferruled coupled-cavity TWT circuit over the V-band frequency range. The simulation results indicate that this circuit has a much higher gain, significantly wider bandwidth, and a much lower voltage requirement than the scaled ring-plane prototype circuit, while retaining its excellent thermal dissipation properties. The finned-ladder circuit has a much larger small-signal gain per wavelength than the ferruled coupled-cavity circuit, but with a moderate sacrifice in bandwidth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70021640','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70021640"><span>Multichannel analysis of surface <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Park, C.B.; Miller, R.D.; Xia, J.</p> <p>1999-01-01</p> <p>The frequency-dependent properties of Rayleigh-type surface <span class="hlt">waves</span> can be utilized for imaging and characterizing the shallow subsurface. Most surface-<span class="hlt">wave</span> analysis relies on the <span class="hlt">accurate</span> calculation of phase velocities for the horizontally traveling fundamental-mode Rayleigh <span class="hlt">wave</span> acquired by stepping out a pair of receivers at intervals based on calculated ground roll wavelengths. Interference by coherent source-generated noise inhibits the reliability of shear-<span class="hlt">wave</span> velocities determined through inversion of the whole <span class="hlt">wave</span> field. Among these nonplanar, nonfundamental-mode Rayleigh <span class="hlt">waves</span> (noise) are body <span class="hlt">waves</span>, scattered and nonsource-generated surface <span class="hlt">waves</span>, and higher-mode surface <span class="hlt">waves</span>. The degree to which each of these types of noise contaminates the dispersion curve and, ultimately, the inverted shear-<span class="hlt">wave</span> velocity profile is dependent on frequency as well as distance from the source. Multichannel recording permits effective identification and isolation of noise according to distinctive trace-to-trace coherency in arrival time and amplitude. An added advantage is the speed and redundancy of the measurement process. Decomposition of a multichannel record into a time variable-frequency format, similar to an uncorrelated Vibroseis record, permits analysis and display of each frequency component in a unique and continuous format. Coherent noise contamination can then be examined and its effects appraised in both frequency and offset space. Separation of frequency components permits real-time maximization of the S/N ratio during acquisition and subsequent processing steps. Linear separation of each ground roll frequency component allows calculation of phase velocities by simply measuring the linear slope of each frequency component. Breaks in coherent surface-<span class="hlt">wave</span> arrivals, observable on the decomposed record, can be compensated for during acquisition and processing. Multichannel recording permits single-measurement surveying of a broad depth range, high levels of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRC..121.1360L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRC..121.1360L"><span>The characteristics and dynamics of <span class="hlt">wave</span>-driven flow across a platform coral reef in the Red Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lentz, S. J.; Churchill, J. H.; Davis, K. A.; Farrar, J. T.; Pineda, J.; Starczak, V.</p> <p>2016-02-01</p> <p>Current dynamics across a platform reef in the Red Sea near Jeddah, Saudi Arabia, are examined using 18 months of current profile, pressure, surface <span class="hlt">wave</span>, and wind observations. The platform reef is 700 m long, 200 m across with spatial and temporal <span class="hlt">variations</span> in water depth over the reef ranging from 0.6 to 1.6 m. Surface <span class="hlt">waves</span> breaking at the seaward edge of the reef cause a 2-10 cm setup of sea level that drives cross-reef currents of 5-20 cm s-1. Bottom stress is a significant component of the <span class="hlt">wave</span> setup balance in the surf zone. Over the reef flat, where <span class="hlt">waves</span> are not breaking, the cross-reef pressure gradient associated with <span class="hlt">wave</span> setup is balanced by bottom stress. The quadratic drag coefficient for the depth-average flow decreases with increasing water depth from Cda = 0.17 in 0.4 m of water to Cda = 0.03 in 1.2 m of water. The observed dependence of the drag coefficient on water depth is consistent with open-channel flow theory and a hydrodynamic roughness of zo = 0.06 m. A simple one-dimensional model driven by incident surface <span class="hlt">waves</span> and wind stress <span class="hlt">accurately</span> reproduces the observed depth-averaged cross-reef currents and a portion of the weaker along-reef currents over the focus reef and two other Red Sea platform reefs. The model indicates the cross-reef current is <span class="hlt">wave</span> forced and the along-reef current is partially wind forced.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28504936','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28504936"><span><span class="hlt">Wave</span> Mode Discrimination of Coded Ultrasonic Guided <span class="hlt">Waves</span> Using Two-Dimensional Compressed Pulse Analysis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Malo, Sergio; Fateri, Sina; Livadas, Makis; Mares, Cristinel; Gan, Tat-Hean</p> <p>2017-07-01</p> <p>Ultrasonic guided <span class="hlt">waves</span> testing is a technique successfully used in many industrial scenarios worldwide. For many complex applications, the dispersive nature and multimode behavior of the technique still poses a challenge for correct defect detection capabilities. In order to improve the performance of the guided <span class="hlt">waves</span>, a 2-D compressed pulse analysis is presented in this paper. This novel technique combines the use of pulse compression and dispersion compensation in order to improve the signal-to-noise ratio (SNR) and temporal-spatial resolution of the signals. The ability of the technique to discriminate different <span class="hlt">wave</span> modes is also highlighted. In addition, an iterative algorithm is developed to identify the <span class="hlt">wave</span> modes of interest using adaptive peak detection to enable automatic <span class="hlt">wave</span> mode discrimination. The employed algorithm is developed in order to pave the way for further in situ applications. The performance of Barker-coded and chirp waveforms is studied in a multimodal scenario where longitudinal and flexural <span class="hlt">wave</span> packets are superposed. The technique is tested in both synthetic and experimental conditions. The enhancements in SNR and temporal resolution are quantified as well as their ability to <span class="hlt">accurately</span> calculate the propagation distance for different <span class="hlt">wave</span> modes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19760037249&hterms=Singled&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DSingled','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19760037249&hterms=Singled&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DSingled"><span>Periodic <span class="hlt">variations</span> in stratospheric-mesospheric temperature from 20-65 km at 80 N to 30 S</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nastrom, G. D.; Belmont, A. D.</p> <p>1975-01-01</p> <p>Results on large-scale periodic <span class="hlt">variations</span> of the stratospheric-mesospheric temperature field based on Meteorological Rocket Network (MRN) measurements are reported for a long-term (12-year) mean, the quasi-biennial oscillation (QBO), and the first three harmonics of the annual <span class="hlt">wave</span> (annual <span class="hlt">wave</span>, semi-annual <span class="hlt">wave</span>, and terannual <span class="hlt">wave</span> or 4-month <span class="hlt">variation</span>). Station-to-station comparisons are tabulated and charted for amplitude and phase of periodic <span class="hlt">variations</span> in the temperature field. Masking and biasing factors, such as diurnal tides, solar radiation <span class="hlt">variations</span>, mean monthly <span class="hlt">variations</span>, instrument lag, aerodynamic heating, are singled out for attention. Models of the stratosphere will have to account for these oscillations of different periods in the thermal field and related properties of the wind fields, with multilayered horizontal stratification with height taken into account.-</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22088050','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22088050"><span>Calculation of the exchange coupling constants of copper binuclear systems based on spin-flip constricted <span class="hlt">variational</span> density functional theory.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhekova, Hristina R; Seth, Michael; Ziegler, Tom</p> <p>2011-11-14</p> <p>We have recently developed a methodology for the calculation of exchange coupling constants J in weakly interacting polynuclear metal clusters. The method is based on unrestricted and restricted second order spin-flip constricted <span class="hlt">variational</span> density functional theory (SF-CV(2)-DFT) and is here applied to eight binuclear copper systems. Comparison of the SF-CV(2)-DFT results with experiment and with results obtained from other DFT and <span class="hlt">wave</span> function based methods has been made. Restricted SF-CV(2)-DFT with the BH&HLYP functional yields consistently J values in excellent agreement with experiment. The results acquired from this scheme are comparable in quality to those obtained by <span class="hlt">accurate</span> multi-reference <span class="hlt">wave</span> function methodologies such as difference dedicated configuration interaction and the complete active space with second-order perturbation theory. © 2011 American Institute of Physics</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRC..123...40T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRC..123...40T"><span>Excitation Location and Seasonal <span class="hlt">Variation</span> of Transoceanic Infragravity <span class="hlt">Waves</span> Observed at an Absolute Pressure Gauge Array</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tonegawa, T.; Fukao, Y.; Shiobara, H.; Sugioka, H.; Ito, A.; Yamashita, M.</p> <p>2018-01-01</p> <p>An array of 10 absolute pressure gauges (APGs) deployed in deep water 50 km east of Aogashima, an island in southern Japan, observed several isolated signals in the infragravity <span class="hlt">wave</span> (IGW) frequency band (0.002-0.03 Hz) during boreal summer, whereas relatively high IGW energy persisted during boreal winter. The isolated IGW shows dispersion with a delay time of 4-5 days as a function of frequency. Here we estimate the excitation locations of IGWs for the two seasons with estimated incoming direction of IGW, calculation of transoceanic IGW trajectories and propagation times, and spatiotemporal <span class="hlt">variations</span> of significant <span class="hlt">wave</span> heights from WAVEWATCH III. In boreal summer, the isolated IGWs are primarily caused by IGW energies excited at the shoreline of South America, based on the following three observations: IGWs observed at the array originated from the east: the easterly ray path from the array reaches South America: and an event-like IGWs were observed at the array when a storm approaches eastward to the shoreline of South America, in which the observed delay time of 4-5 days was also supported by the frequency-dependent calculation of IGW propagation times. In boreal winter, the incessant IGWs consist of transoceanic IGW energies leaked from the shoreline, primarily from North America, and secondly from South America and the western Aleutian Islands.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRA..123.4129F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRA..123.4129F"><span>MAVEN Observations of Solar Wind-Driven Magnetosonic <span class="hlt">Waves</span> Heating the Martian Dayside Ionosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fowler, C. M.; Andersson, L.; Ergun, R. E.; Harada, Y.; Hara, T.; Collinson, G.; Peterson, W. K.; Espley, J.; Halekas, J.; Mcfadden, J.; Mitchell, D. L.; Mazelle, C.; Benna, M.; Jakosky, B. M.</p> <p>2018-05-01</p> <p>We present Mars Atmosphere and Volatile EvolutioN observations of large-amplitude magnetosonic <span class="hlt">waves</span> propagating through the magnetosheath into the Martian ionosphere near the subsolar point on the dayside of the planet. The observed <span class="hlt">waves</span> grow in amplitude as predicted for a <span class="hlt">wave</span> propagating into a denser, charged medium, with <span class="hlt">wave</span> amplitudes reaching 25 nT, equivalent to ˜40% of the background field strength. These <span class="hlt">waves</span> drive significant density and temperature <span class="hlt">variations</span> (˜20% to 100% in amplitude) in the suprathermal electrons and light ion species (H+) that correlate with compressional fronts of the magnetosonic <span class="hlt">waves</span>. Density and temperature <span class="hlt">variations</span> are also observed for the ionospheric electrons, and heavy ion species (O+ and O2+); however, these <span class="hlt">variations</span> are not in phase with the magnetic field <span class="hlt">variations</span>. Whistler <span class="hlt">waves</span> are observed at compressional <span class="hlt">wave</span> fronts and are thought to be produced by unstable, anistropic suprathermal electrons. The magnetosonic <span class="hlt">waves</span> drive significant ion and electron heating down to just above the exobase region. Ion heating rates are estimated to be between 0.03 and 0.2 eVs-1 per ion, and heavier ions could thus gain escape energy if located in this heating region for ˜10-70 s. The measured ionospheric density profile indicates severe ionospheric erosion above the exobase region, and this is likely caused by substantial ion outflow that is driven by the observed heating. The effectiveness of these magnetosonic <span class="hlt">waves</span> to energize the plasma close to the exobase could have important implications for the long-term climate evolution for unmagnetized bodies that are exposed to the solar wind.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRA..123.3005X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRA..123.3005X"><span>Two Day <span class="hlt">Wave</span> Traveling Westward With <span class="hlt">Wave</span> Number 1 During the Sudden Stratospheric Warming in January 2017</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xiong, Jiangang; Wan, Weixing; Ding, Feng; Liu, Libo; Hu, Lianhuan; Yan, Chunxiao</p> <p>2018-04-01</p> <p>Quasi-two day <span class="hlt">wave</span> propagating westward with <span class="hlt">wave</span> number 1 (W1) in January 2017 is studied using global temperature observed by Sounding of the Atmosphere using Broadband Emission Radiometry and wind observed by a meteor radar at Fuke, China (19.0°N, 109.8°E). The amplitude of W1 significantly enhances during January 2017, when two stratospheric warming events occur. The temperature perturbation of W1 reaches maximum amplitude of more than 6 K at latitude ±15° around 84 km and 95 km. The structure of temperature W1 is symmetric with regard to the equator. The temporal <span class="hlt">variation</span> of W1 is consistent with the stationary planetary <span class="hlt">wave</span> with <span class="hlt">wave</span> number 2 (SPW2), but contrary to the quasi-two day <span class="hlt">wave</span> propagating westward with <span class="hlt">wave</span> number 3 (W3). When SPW2 is large during two sudden stratospheric warming events, energy transfers from W3 to W1. Two bursts of the 2 day <span class="hlt">wave</span> in meridional wind observed by the meteor radar are just corresponding to the local maxima of W3 and W1, respectively. We conclude that during January 2017, W1 is generated by the nonlinear interaction between SPW2 and W3. SPW2 which is modulated by the quasi-16 day perturbation in the stratosphere plays a key role in the energy transmission from W3 to W1, and it is responsible for the 16 day <span class="hlt">variation</span> of W1.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.S33C2785S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.S33C2785S"><span>Spectral-Element Seismic <span class="hlt">Wave</span> Propagation Codes for both Forward Modeling in Complex Media and Adjoint Tomography</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, J. A.; Peter, D. B.; Tromp, J.; Komatitsch, D.; Lefebvre, M. P.</p> <p>2015-12-01</p> <p>We present both SPECFEM3D_Cartesian and SPECFEM3D_GLOBE open-source codes, representing high-performance numerical <span class="hlt">wave</span> solvers simulating seismic <span class="hlt">wave</span> propagation for local-, regional-, and global-scale application. These codes are suitable for both forward propagation in complex media and tomographic imaging. Both solvers compute highly <span class="hlt">accurate</span> seismic <span class="hlt">wave</span> fields using the continuous Galerkin spectral-element method on unstructured meshes. Lateral <span class="hlt">variations</span> in compressional- and shear-<span class="hlt">wave</span> speeds, density, as well as 3D attenuation Q models, topography and fluid-solid coupling are all readily included in both codes. For global simulations, effects due to rotation, ellipticity, the oceans, 3D crustal models, and self-gravitation are additionally included. Both packages provide forward and adjoint functionality suitable for adjoint tomography on high-performance computing architectures. We highlight the most recent release of the global version which includes improved performance, simultaneous MPI runs, OpenCL and CUDA support via an automatic source-to-source transformation library (BOAST), parallel I/O readers and writers for databases using ADIOS and seismograms using the recently developed Adaptable Seismic Data Format (ASDF) with built-in provenance. This makes our spectral-element solvers current state-of-the-art, open-source community codes for high-performance seismic <span class="hlt">wave</span> propagation on arbitrarily complex 3D models. Together with these solvers, we provide full-waveform inversion tools to image the Earth's interior at unprecedented resolution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860018250&hterms=attention+pictures&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dattention%2Bpictures','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860018250&hterms=attention+pictures&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dattention%2Bpictures"><span>Seasonal <span class="hlt">variation</span> of the stratospheric circulation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hirota, I.; Shiotani, M.</p> <p>1985-01-01</p> <p>An extensive analysis is made of the extratropical stratospheric circulation in terms of the seasonal <span class="hlt">variation</span> of large-scale motion fields, with the aid of height and temperature data obtained from the TIROS satellite. Special attention is paid to a comparison of climatological aspects between the Northern Hemisphere (NH) and the Southern Hemisphere (SH). In order to see the general picture of the annual mach of the upper stratosphere, the zonal mean values of geopotential height of the 1 mb level at 70 deg N and 70 deg S were plotted on the daily basis throughout a year. It is observed that, during the winter, the zonal mean 1 mb height in the NH is much more variable than that in the SH. It is also notable that the SH height is rather oscillatory throughout the longer period from midwinter to early summer. Since the zonal mean height in the polar latitude is a rough measure of the mean zonal flow in extratropical latitudes, the difference of the seasonal <span class="hlt">variation</span> between the two hemispheres mentioned above is considered to be due mainly to the planetary <span class="hlt">wave</span>-mean flow interaction in the middle atmosphere. The <span class="hlt">wave</span> activity in the middle atmosphere is represented more rigorously by the Eliassen-Palm flux associated with vertically propagating planetary <span class="hlt">waves</span> forced from below. The day-to-day <span class="hlt">variation</span> of the EP flux in the upper stratosphere shows that the <span class="hlt">wave</span> activity varies intermittently with a characteristic time scale of about two weeks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017OcMod.119...94S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017OcMod.119...94S"><span>Simulation of breaking <span class="hlt">waves</span> using the high-order spectral method with laboratory experiments: <span class="hlt">Wave</span>-breaking onset</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Seiffert, Betsy R.; Ducrozet, Guillaume; Bonnefoy, Félicien</p> <p>2017-11-01</p> <p> <span class="hlt">waves</span> provides a wide range of breaking-<span class="hlt">wave</span> strengths, types and scales for validation of the model. A comparison of calculations made using HOS-NWT with experimental measurements show that the model is successful at predicting the occurrence of <span class="hlt">wave</span> breaking, as well as <span class="hlt">accurately</span> calculating breaking onset time and location. Although the current study is limited to a unidirectional <span class="hlt">wave</span> field, the success of the <span class="hlt">wave</span>-breaking model presented provides the basis for application of the model in a multidirectional <span class="hlt">wave</span> field. By including <span class="hlt">wave</span> breaking onset with the addition of an appropriate energy dissipation model into HOS-NWT, we can increase the application range of the model, as well as decrease the occurrence of numerical instabilities that are associated with breaking <span class="hlt">waves</span> in a potential flow solver. An <span class="hlt">accurate</span> description of the <span class="hlt">wave</span> field is useful for predicting the dynamic response of offshore vessels and marine renewable energy devices, predicting loads on marine structures and the general physics of ocean <span class="hlt">waves</span>, for example.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70179088','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70179088"><span>A multimodal <span class="hlt">wave</span> spectrum-based approach for statistical downscaling of local <span class="hlt">wave</span> climate</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hegermiller, Christie; Antolinez, Jose A A; Rueda, Ana C.; Camus, Paula; Perez, Jorge; Erikson, Li; Barnard, Patrick; Mendez, Fernando J.</p> <p>2017-01-01</p> <p>Characterization of <span class="hlt">wave</span> climate by bulk <span class="hlt">wave</span> parameters is insufficient for many coastal studies, including those focused on assessing coastal hazards and long-term <span class="hlt">wave</span> climate influences on coastal evolution. This issue is particularly relevant for studies using statistical downscaling of atmospheric fields to local <span class="hlt">wave</span> conditions, which are often multimodal in large ocean basins (e.g. the Pacific). Swell may be generated in vastly different <span class="hlt">wave</span> generation regions, yielding complex <span class="hlt">wave</span> spectra that are inadequately represented by a single set of bulk <span class="hlt">wave</span> parameters. Furthermore, the relationship between atmospheric systems and local <span class="hlt">wave</span> conditions is complicated by <span class="hlt">variations</span> in arrival time of <span class="hlt">wave</span> groups from different parts of the basin. Here, we address these two challenges by improving upon the spatiotemporal definition of the atmospheric predictor used in statistical downscaling of local <span class="hlt">wave</span> climate. The improved methodology separates the local <span class="hlt">wave</span> spectrum into “<span class="hlt">wave</span> families,” defined by spectral peaks and discrete generation regions, and relates atmospheric conditions in distant regions of the ocean basin to local <span class="hlt">wave</span> conditions by incorporating travel times computed from effective energy flux across the ocean basin. When applied to locations with multimodal <span class="hlt">wave</span> spectra, including Southern California and Trujillo, Peru, the new methodology improves the ability of the statistical model to project significant <span class="hlt">wave</span> height, peak period, and direction for each <span class="hlt">wave</span> family, retaining more information from the full <span class="hlt">wave</span> spectrum. This work is the base of statistical downscaling by weather types, which has recently been applied to coastal flooding and morphodynamic applications.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005JAtS...62.4196C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005JAtS...62.4196C"><span>Constraints on <span class="hlt">Wave</span> Drag Parameterization Schemes for Simulating the Quasi-Biennial Oscillation. Part II: Combined Effects of Gravity <span class="hlt">Waves</span> and Equatorial Planetary <span class="hlt">Waves</span>.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Campbell, Lucy J.; Shepherd, Theodore G.</p> <p>2005-12-01</p> <p>This study examines the effect of combining equatorial planetary <span class="hlt">wave</span> drag and gravity <span class="hlt">wave</span> drag in a one-dimensional zonal mean model of the quasi-biennial oscillation (QBO). Several different combinations of planetary <span class="hlt">wave</span> and gravity <span class="hlt">wave</span> drag schemes are considered in the investigations, with the aim being to assess which aspects of the different schemes affect the nature of the modeled QBO. Results show that it is possible to generate a realistic-looking QBO with various combinations of drag from the two types of <span class="hlt">waves</span>, but there are some constraints on the <span class="hlt">wave</span> input spectra and amplitudes. For example, if the phase speeds of the gravity <span class="hlt">waves</span> in the input spectrum are large relative to those of the equatorial planetary <span class="hlt">waves</span>, critical level absorption of the equatorial planetary <span class="hlt">waves</span> may occur. The resulting mean-wind oscillation, in that case, is driven almost exclusively by the gravity <span class="hlt">wave</span> drag, with only a small contribution from the planetary <span class="hlt">waves</span> at low levels. With an appropriate choice of <span class="hlt">wave</span> input parameters, it is possible to obtain a QBO with a realistic period and to which both types of <span class="hlt">waves</span> contribute. This is the regime in which the terrestrial QBO appears to reside. There may also be constraints on the initial strength of the wind shear, and these are similar to the constraints that apply when gravity <span class="hlt">wave</span> drag is used without any planetary <span class="hlt">wave</span> drag.In recent years, it has been observed that, in order to simulate the QBO <span class="hlt">accurately</span>, general circulation models require parameterized gravity <span class="hlt">wave</span> drag, in addition to the drag from resolved planetary-scale <span class="hlt">waves</span>, and that even if the planetary <span class="hlt">wave</span> amplitudes are incorrect, the gravity <span class="hlt">wave</span> drag can be adjusted to compensate. This study provides a basis for knowing that such a compensation is possible.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940026147','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940026147"><span>Development of an <span class="hlt">accurate</span> transmission line fault locator using the global positioning system satellites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lee, Harry</p> <p>1994-01-01</p> <p>A highly <span class="hlt">accurate</span> transmission line fault locator based on the traveling-<span class="hlt">wave</span> principle was developed and successfully operated within B.C. Hydro. A transmission line fault produces a fast-risetime traveling <span class="hlt">wave</span> at the fault point which propagates along the transmission line. This fault locator system consists of traveling <span class="hlt">wave</span> detectors located at key substations which detect and time tag the leading edge of the fault-generated traveling <span class="hlt">wave</span> as if passes through. A master station gathers the time-tagged information from the remote detectors and determines the location of the fault. Precise time is a key element to the success of this system. This fault locator system derives its timing from the Global Positioning System (GPS) satellites. System tests confirmed the accuracy of locating faults to within the design objective of +/-300 meters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018OcDyn..68...65S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018OcDyn..68...65S"><span>Simulation of breaking <span class="hlt">waves</span> using the high-order spectral method with laboratory experiments: <span class="hlt">wave</span>-breaking energy dissipation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Seiffert, Betsy R.; Ducrozet, Guillaume</p> <p>2018-01-01</p> <p>We examine the implementation of a <span class="hlt">wave</span>-breaking mechanism into a nonlinear potential flow solver. The success of the mechanism will be studied by implementing it into the numerical model HOS-NWT, which is a computationally efficient, open source code that solves for the free surface in a numerical <span class="hlt">wave</span> tank using the high-order spectral (HOS) method. Once the breaking mechanism is validated, it can be implemented into other nonlinear potential flow models. To solve for <span class="hlt">wave</span>-breaking, first a <span class="hlt">wave</span>-breaking onset parameter is identified, and then a method for computing <span class="hlt">wave</span>-breaking associated energy loss is determined. <span class="hlt">Wave</span>-breaking onset is calculated using a breaking criteria introduced by Barthelemy et al. (J Fluid Mech https://arxiv.org/pdf/1508.06002.pdf, submitted) and validated with the experiments of Saket et al. (J Fluid Mech 811:642-658, 2017). <span class="hlt">Wave</span>-breaking energy dissipation is calculated by adding a viscous diffusion term computed using an eddy viscosity parameter introduced by Tian et al. (Phys Fluids 20(6): 066,604, 2008, Phys Fluids 24(3), 2012), which is estimated based on the pre-breaking <span class="hlt">wave</span> geometry. A set of two-dimensional experiments is conducted to validate the implemented <span class="hlt">wave</span> breaking mechanism at a large scale. Breaking <span class="hlt">waves</span> are generated by using traditional methods of evolution of focused <span class="hlt">waves</span> and modulational instability, as well as irregular breaking <span class="hlt">waves</span> with a range of primary frequencies, providing a wide range of breaking conditions to validate the solver. Furthermore, adjustments are made to the method of application and coefficient of the viscous diffusion term with negligible difference, supporting the robustness of the eddy viscosity parameter. The model is able to <span class="hlt">accurately</span> predict surface elevation and corresponding frequency/amplitude spectrum, as well as energy dissipation when compared with the experimental measurements. This suggests the model is capable of calculating <span class="hlt">wave</span>-breaking onset and energy dissipation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhRvB..97w5103F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhRvB..97w5103F"><span>Dynamical structure factor of the J1-J2 Heisenberg model in one dimension: The <span class="hlt">variational</span> Monte Carlo approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ferrari, Francesco; Parola, Alberto; Sorella, Sandro; Becca, Federico</p> <p>2018-06-01</p> <p>The dynamical spin structure factor is computed within a <span class="hlt">variational</span> framework to study the one-dimensional J1-J2 Heisenberg model. Starting from Gutzwiller-projected fermionic <span class="hlt">wave</span> functions, the low-energy spectrum is constructed from two-spinon excitations. The direct comparison with Lanczos calculations on small clusters demonstrates the excellent description of both gapless and gapped (dimerized) phases, including incommensurate structures for J2/J1>0.5 . Calculations on large clusters show how the intensity evolves when increasing the frustrating ratio and give an unprecedented <span class="hlt">accurate</span> characterization of the dynamical properties of (nonintegrable) frustrated spin models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22257096-hydroelastic-response-floating-runway-cnoidal-waves','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22257096-hydroelastic-response-floating-runway-cnoidal-waves"><span>Hydroelastic response of a floating runway to cnoidal <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Ertekin, R. C., E-mail: ertekin@hawaii.edu; Xia, Dingwu</p> <p>2014-02-15</p> <p>The hydroelastic response of mat-type Very Large Floating Structures (VLFSs) to severe sea conditions, such as tsunamis and hurricanes, must be assessed for safety and survivability. An efficient and robust nonlinear hydroelastic model is required to predict <span class="hlt">accurately</span> the motion of and the dynamic loads on a VLFS due to such large <span class="hlt">waves</span>. We develop a nonlinear theory to predict the hydroelastic response of a VLFS in the presence of cnoidal <span class="hlt">waves</span> and compare the predictions with the linear theory that is also developed here. This hydroelastic problem is formulated by directly coupling the structure with the fluid, by usemore » of the Level I Green-Naghdi theory for the fluid motion and the Kirchhoff thin plate theory for the runway. The coupled fluid structure system, together with the appropriate jump conditions are solved in two-dimensions by the finite-difference method. The numerical model is used to study the nonlinear response of a VLFS to storm <span class="hlt">waves</span> which are modeled by use of the cnoidal-<span class="hlt">wave</span> theory. Parametric studies show that the nonlinearity of the <span class="hlt">waves</span> is very important in <span class="hlt">accurately</span> predicting the dynamic bending moment and <span class="hlt">wave</span> run-up on a VLFS in high seas.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/AD1042981','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/AD1042981"><span>Develop <span class="hlt">Accurate</span> Methods for Characterizing and Quantifying Cohesive Sediment Erosion Under Combined Current-<span class="hlt">Wave</span> Conditions</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2017-09-01</p> <p>ER D C/ CH L TR -1 7- 15 Strategic Environmental Research and Development Program Develop <span class="hlt">Accurate</span> Methods for Characterizing and...current environments. This research will provide more <span class="hlt">accurate</span> methods for assessing contaminated sediment stability for many DoD and Environmental...47.88026 pascals yards 0.9144 meters ERDC/CHL TR-17-15 xi Executive Summary Objective The proposed research goal is to develop laboratory methods</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27951503','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27951503"><span>Effect of pressurization on helical guided <span class="hlt">wave</span> energy velocity in fluid-filled pipes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dubuc, Brennan; Ebrahimkhanlou, Arvin; Salamone, Salvatore</p> <p>2017-03-01</p> <p>The effect of pressurization stresses on helical guided <span class="hlt">waves</span> in a thin-walled fluid-filled pipe is studied by modeling leaky Lamb <span class="hlt">waves</span> in a stressed plate bordered by fluid. Fluid pressurization produces hoop and longitudinal stresses in a thin-walled pipe, which corresponds to biaxial in-plane stress in a plate waveguide model. The effect of stress on guided <span class="hlt">wave</span> propagation is accounted for through nonlinear elasticity and finite deformation theory. Emphasis is placed on the stress dependence of the energy velocity of the guided <span class="hlt">wave</span> modes. For this purpose, an expression for the energy velocity of leaky Lamb <span class="hlt">waves</span> in a stressed plate is derived. Theoretical results are presented for the mode, frequency, and directional dependent <span class="hlt">variations</span> in energy velocity with respect to stress. An experimental setup is designed for measuring <span class="hlt">variations</span> in helical <span class="hlt">wave</span> energy velocity in a thin-walled water-filled steel pipe at different levels of pressure. Good agreement is achieved between the experimental <span class="hlt">variations</span> in energy velocity for the helical guided <span class="hlt">waves</span> and the theoretical leaky Lamb <span class="hlt">wave</span> solutions. Copyright © 2016 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19880007150','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19880007150"><span>Relativistic electromagnetic <span class="hlt">waves</span> in an electron-ion plasma</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chian, Abraham C.-L.; Kennel, Charles F.</p> <p>1987-01-01</p> <p>High power laser beams can drive plasma particles to relativistic energies. An <span class="hlt">accurate</span> description of strong <span class="hlt">waves</span> requires the inclusion of ion dynamics in the analysis. The equations governing the propagation of relativistic electromagnetic <span class="hlt">waves</span> in a cold electron-ion plasma can be reduced to two equations expressing conservation of energy-momentum of the system. The two conservation constants are functions of the plasma stream velocity, the <span class="hlt">wave</span> velocity, the <span class="hlt">wave</span> amplitude, and the electron-ion mass ratio. The dynamic parameter, expressing electron-ion momentum conversation in the laboratory frame, can be regarded as an adjustable quantity, a suitable choice of which will yield self-consistent solutions when other plasma parameters were specified. Circularly polarized electromagnetic <span class="hlt">waves</span> and electrostatic plasma <span class="hlt">waves</span> are used as illustrations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011EL.....9553001S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011EL.....9553001S"><span><span class="hlt">Accurately</span> predicting the structure, density, and hydrostatic compression of crystalline β-1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane based on its <span class="hlt">wave</span>-function-based potential</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Song, H.-J.; Huang, F.</p> <p>2011-09-01</p> <p>A <span class="hlt">wave</span>-function-based intermolecular potential of the β phase 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX) molecule has been constructed from first principles using the Williams-Stone-Misquitta method and the symmetry-adapted perturbation theory. Using the potential and its derivatives, we have <span class="hlt">accurately</span> predicted not only the structure and lattice energy of the crystalline β-HMX at 0 K, but also its densities at temperatures of 0-403 K within an accuracy of 1% of density. The calculated densities at pressures within 0-6 GPa excellently agree with the results from the experiments on hydrostatic compression.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AIPC.1500..186W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AIPC.1500..186W"><span>Alfvén <span class="hlt">wave</span> interactions in the solar wind</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Webb, G. M.; McKenzie, J. F.; Hu, Q.; le Roux, J. A.; Zank, G. P.</p> <p>2012-11-01</p> <p>Alfvén <span class="hlt">wave</span> mixing (interaction) equations used in locally incompressible turbulence transport equations in the solar wind are analyzed from the perspective of linear <span class="hlt">wave</span> theory. The connection between the <span class="hlt">wave</span> mixing equations and non-WKB Alfven <span class="hlt">wave</span> driven wind theories are delineated. We discuss the physical <span class="hlt">wave</span> energy equation and the canonical <span class="hlt">wave</span> energy equation for non-WKB Alfven <span class="hlt">waves</span> and the WKB limit. <span class="hlt">Variational</span> principles and conservation laws for the linear <span class="hlt">wave</span> mixing equations for the Heinemann and Olbert non-WKB wind model are obtained. The connection with <span class="hlt">wave</span> mixing equations used in locally incompressible turbulence transport in the solar wind are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/9069','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/9069"><span>Nondestructive evaluation of green wood using stress <span class="hlt">wave</span> and transverse vibration techniques</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Udaya B. Halabe; Gangadhar M. Bidigalu; Hota V.S. GangaRao; Robert J. Ross</p> <p>1997-01-01</p> <p>Longitudinal stress <span class="hlt">wave</span> and transverse vibration nondestructive testing (NDT) techniques have proven to be <span class="hlt">accurate</span> means of evaluating the quality of wood based products. Researchers have found strong relationships between stress <span class="hlt">wave</span> and transverse vibration parameters (e.g., <span class="hlt">wave</span> velocity and modulus of elasticity predicted using NDT measurements) with the actual...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1251074-accurate-atomistic-first-principles-calculations-electronic-stopping','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1251074-accurate-atomistic-first-principles-calculations-electronic-stopping"><span><span class="hlt">Accurate</span> atomistic first-principles calculations of electronic stopping</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Schleife, André; Kanai, Yosuke; Correa, Alfredo A.</p> <p>2015-01-20</p> <p>In this paper, we show that atomistic first-principles calculations based on real-time propagation within time-dependent density functional theory are capable of <span class="hlt">accurately</span> describing electronic stopping of light projectile atoms in metal hosts over a wide range of projectile velocities. In particular, we employ a plane-<span class="hlt">wave</span> pseudopotential scheme to solve time-dependent Kohn-Sham equations for representative systems of H and He projectiles in crystalline aluminum. This approach to simulate nonadiabatic electron-ion interaction provides an <span class="hlt">accurate</span> framework that allows for quantitative comparison with experiment without introducing ad hoc parameters such as effective charges, or assumptions about the dielectric function. Finally, our work clearlymore » shows that this atomistic first-principles description of electronic stopping is able to disentangle contributions due to tightly bound semicore electrons and geometric aspects of the stopping geometry (channeling versus off-channeling) in a wide range of projectile velocities.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25096095','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25096095"><span>Reconstructing surface <span class="hlt">wave</span> profiles from reflected acoustic pulses using multiple receivers.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Walstead, Sean P; Deane, Grant B</p> <p>2014-08-01</p> <p>Surface <span class="hlt">wave</span> shapes are determined by analyzing underwater reflected acoustic signals collected at multiple receivers. The transmitted signals are of nominal frequency 300 kHz and are reflected off surface gravity <span class="hlt">waves</span> that are paddle-generated in a <span class="hlt">wave</span> tank. An inverse processing algorithm reconstructs 50 surface <span class="hlt">wave</span> shapes over a length span of 2.10 m. The inverse scheme uses a broadband forward scattering model based on Kirchhoff's diffraction formula to determine <span class="hlt">wave</span> shapes. The surface reconstruction algorithm is self-starting in that source and receiver geometry and initial estimates of <span class="hlt">wave</span> shape are determined from the same acoustic signals used in the inverse processing. A high speed camera provides ground-truth measurements of the surface <span class="hlt">wave</span> field for comparison with the acoustically derived surface <span class="hlt">waves</span>. Within Fresnel zone regions the statistical confidence of the inversely optimized surface profile exceeds that of the camera profile. Reconstructed surfaces are <span class="hlt">accurate</span> to a resolution of about a quarter-wavelength of the acoustic pulse only within Fresnel zones associated with each source and receiver pair. Multiple isolated Fresnel zones from multiple receivers extend the spatial extent of <span class="hlt">accurate</span> surface reconstruction while overlapping Fresnel zones increase confidence in the optimized profiles there.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017APS..APR.X6002M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..APR.X6002M"><span>Bayesian reconstruction of gravitational <span class="hlt">wave</span> bursts using chirplets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Millhouse, Margaret; Cornish, Neil; Littenberg, Tyson</p> <p>2017-01-01</p> <p>The Bayes<span class="hlt">Wave</span> algorithm has been shown to <span class="hlt">accurately</span> reconstruct unmodeled short duration gravitational <span class="hlt">wave</span> bursts and to distinguish between astrophysical signals and transient noise events. Bayes<span class="hlt">Wave</span> does this by using a variable number of sine-Gaussian (Morlet) wavelets to reconstruct data in multiple interferometers. While the Morlet wavelets can be summed together to produce any possible waveform, there could be other wavelet functions that improve the performance. Because we expect most astrophysical gravitational <span class="hlt">wave</span> signals to evolve in frequency, modified Morlet wavelets with linear frequency evolution - called chirplets - may better reconstruct signals with fewer wavelets. We compare the performance of Bayes<span class="hlt">Wave</span> using Morlet wavelets and chirplets on a variety of simulated signals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002PhRvB..66g3103S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002PhRvB..66g3103S"><span>Comparison of <span class="hlt">variational</span> real-space representations of the kinetic energy operator</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Skylaris, Chris-Kriton; Diéguez, Oswaldo; Haynes, Peter D.; Payne, Mike C.</p> <p>2002-08-01</p> <p>We present a comparison of real-space methods based on regular grids for electronic structure calculations that are designed to have basis set <span class="hlt">variational</span> properties, using as a reference the conventional method of finite differences (a real-space method that is not <span class="hlt">variational</span>) and the reciprocal-space plane-<span class="hlt">wave</span> method which is fully <span class="hlt">variational</span>. We find that a definition of the finite-difference method [P. Maragakis, J. Soler, and E. Kaxiras, Phys. Rev. B 64, 193101 (2001)] satisfies one of the two properties of <span class="hlt">variational</span> behavior at the cost of larger errors than the conventional finite-difference method. On the other hand, a technique which represents functions in a number of plane <span class="hlt">waves</span> which is independent of system size closely follows the plane-<span class="hlt">wave</span> method and therefore also the criteria for <span class="hlt">variational</span> behavior. Its application is only limited by the requirement of having functions strictly localized in regions of real space, but this is a characteristic of an increasing number of modern real-space methods, as they are designed to have a computational cost that scales linearly with system size.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1919530P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1919530P"><span>Long-term <span class="hlt">wave</span> measurements in a climate change perspective.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pomaro, Angela; Bertotti, Luciana; Cavaleri, Luigi; Lionello, Piero; Portilla-Yandun, Jesus</p> <p>2017-04-01</p> <p>At present multi-decadal time series of <span class="hlt">wave</span> data needed for climate studies are generally provided by long term model simulations (hindcasts) covering the area of interest. Examples, among many, at different scales are <span class="hlt">wave</span> hindcasts adopting the wind fields of the ERA-Interim reanalysis of the European Centre for Medium-Range Weather Forecasts (ECMWF, Reading, U.K.) at the global level and by regional re-analysis as for the Mediterranean Sea (Lionello and Sanna, 2006). Valuable as they are, these estimates are necessarily affected by the approximations involved, the more so because of the problems encountered within modelling processes in small basins using coarse resolution wind fields (Cavaleri and Bertotti, 2004). On the contrary, multi-decadal observed time series are rare. They have the evident advantage of somehow representing the real evolution of the <span class="hlt">waves</span>, without the shortcomings associated with the limitation of models in reproducing the actual processes and the real variability within the <span class="hlt">wave</span> fields. Obviously, observed <span class="hlt">wave</span> time series are not exempt of problems. They represent a very local information, hence their use to describe the <span class="hlt">wave</span> evolution at large scale is sometimes arguable and, in general, it needs the support of model simulations assessing to which extent the local value is representative of a large scale evolution. Local effects may prevent the identification of trends that are indeed present at large scale. Moreover, a regular maintenance, <span class="hlt">accurate</span> monitoring and metadata information are crucial issues when considering the reliability of a time series for climate applications. Of course, where available, especially if for several decades, measured data are of great value for a number of reasons and can be valuable clues to delve further into the physics of the processes of interest, especially if considering that <span class="hlt">waves</span>, as an integrated product of the local climate, if available in an area sensitive to even limited changes of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29050824','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29050824"><span>In vivo repeatability of the pulse <span class="hlt">wave</span> inverse problem in human carotid arteries.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>McGarry, Matthew; Nauleau, Pierre; Apostolakis, Iason; Konofagou, Elisa</p> <p>2017-11-07</p> <p><span class="hlt">Accurate</span> arterial stiffness measurement would improve diagnosis and monitoring for many diseases. Atherosclerotic plaques and aneurysms are expected to involve focal changes in vessel wall properties; therefore, a method to image the stiffness <span class="hlt">variation</span> would be a valuable clinical tool. The pulse <span class="hlt">wave</span> inverse problem (PWIP) fits unknown parameters from a computational model of arterial pulse <span class="hlt">wave</span> propagation to ultrasound-based measurements of vessel wall displacements by minimizing the difference between the model and measured displacements. The PWIP has been validated in phantoms, and this study presents the first in vivo demonstration. The common carotid arteries of five healthy volunteers were imaged five times in a single session with repositioning of the probe and subject between each scan. The 1D finite difference computational model used in the PWIP spanned from the start of the transducer to the carotid bifurcation, where a resistance outlet boundary condition was applied to approximately model the downstream reflection of the pulse <span class="hlt">wave</span>. Unknown parameters that were estimated by the PWIP included a 10-segment linear piecewise compliance distribution and 16 discrete cosine transformation coefficients for each of the inlet boundary conditions. Input data was selected to include pulse <span class="hlt">waves</span> resulting from the primary pulse and dicrotic notch. The recovered compliance maps indicate that the compliance increases close to the bifurcation, and the variability of the average pulse <span class="hlt">wave</span> velocity estimated through the PWIP is on the order of 11%, which is similar to that of the conventional processing technique which tracks the wavefront arrival time (13%). Copyright © 2017 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1356140','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1356140"><span>The lateral <span class="hlt">variation</span> of P n velocity gradient under Eurasia</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Yang, Xiaoning</p> <p></p> <p>We report that mantle lid P <span class="hlt">wave</span> velocity gradient, or P n velocity gradient, reflects the depth and lateral <span class="hlt">variations</span> of thermal and rheological state of the uppermost mantle. Mapping the P n velocity gradient and its lateral <span class="hlt">variation</span> helps us gain insight into the temperature, composition, and dynamics of the uppermost mantle. In addition, because P n velocity gradient has profound influence on P n propagation behavior, an <span class="hlt">accurate</span> mapping of P n velocity gradient also improves the modeling and prediction of P n travel times and amplitudes. In this study, I used measured P n travel times tomore » derive path-specific P n velocity gradients. I then inverted these velocity gradients for two-dimensional (2-D) P n velocity-gradient models for Eurasia based on the assumption that a path-specific Pn velocity gradient is the mean of laterally varying P n velocity gradients along the P n path. Result from a Monte Carlo simulation indicates that the assumption is appropriate. The 2-D velocity-gradient models show that most of Eurasia has positive velocity gradients. High velocity gradients exist mainly in tectonically active regions. Most tectonically stable regions show low and more uniform velocity gradients. In conclusion, strong velocity-gradient <span class="hlt">variations</span> occur largely along convergent plate boundaries, particularly under overriding plates.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1356140-lateral-variation-pn-velocity-gradient-under-eurasia','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1356140-lateral-variation-pn-velocity-gradient-under-eurasia"><span>The lateral <span class="hlt">variation</span> of P n velocity gradient under Eurasia</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Yang, Xiaoning</p> <p>2017-05-03</p> <p>We report that mantle lid P <span class="hlt">wave</span> velocity gradient, or P n velocity gradient, reflects the depth and lateral <span class="hlt">variations</span> of thermal and rheological state of the uppermost mantle. Mapping the P n velocity gradient and its lateral <span class="hlt">variation</span> helps us gain insight into the temperature, composition, and dynamics of the uppermost mantle. In addition, because P n velocity gradient has profound influence on P n propagation behavior, an <span class="hlt">accurate</span> mapping of P n velocity gradient also improves the modeling and prediction of P n travel times and amplitudes. In this study, I used measured P n travel times tomore » derive path-specific P n velocity gradients. I then inverted these velocity gradients for two-dimensional (2-D) P n velocity-gradient models for Eurasia based on the assumption that a path-specific Pn velocity gradient is the mean of laterally varying P n velocity gradients along the P n path. Result from a Monte Carlo simulation indicates that the assumption is appropriate. The 2-D velocity-gradient models show that most of Eurasia has positive velocity gradients. High velocity gradients exist mainly in tectonically active regions. Most tectonically stable regions show low and more uniform velocity gradients. In conclusion, strong velocity-gradient <span class="hlt">variations</span> occur largely along convergent plate boundaries, particularly under overriding plates.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21035829','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21035829"><span>Love <span class="hlt">waves</span> in functionally graded piezoelectric materials by stiffness matrix method.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ben Salah, Issam; Wali, Yassine; Ben Ghozlen, Mohamed Hédi</p> <p>2011-04-01</p> <p>A numerical matrix method relative to the propagation of ultrasonic guided <span class="hlt">waves</span> in functionally graded piezoelectric heterostructure is given in order to make a comparative study with the respective performances of analytical methods proposed in literature. The preliminary obtained results show a good agreement, however numerical approach has the advantage of conceptual simplicity and flexibility brought about by the stiffness matrix method. The propagation behaviour of Love <span class="hlt">waves</span> in a functionally graded piezoelectric material (FGPM) is investigated in this article. It involves a thin FGPM layer bonded perfectly to an elastic substrate. The inhomogeneous FGPM heterostructure has been stratified along the depth direction, hence each state can be considered as homogeneous and the ordinary differential equation method is applied. The obtained solutions are used to study the effect of an exponential gradient applied to physical properties. Such numerical approach allows applying different gradient <span class="hlt">variation</span> for mechanical and electrical properties. For this case, the obtained results reveal opposite effects. The dispersive curves and phase velocities of the Love <span class="hlt">wave</span> propagation in the layered piezoelectric film are obtained for electrical open and short cases on the free surface, respectively. The effect of gradient coefficients on coupled electromechanical factor, on the stress fields, the electrical potential and the mechanical displacement are discussed, respectively. Illustration is achieved on the well known heterostructure PZT-5H/SiO(2), the obtained results are especially useful in the design of high-performance acoustic surface devices and <span class="hlt">accurately</span> prediction of the Love <span class="hlt">wave</span> propagation behaviour. Copyright © 2010 Elsevier B.V. All rights reserved.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19870001023','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19870001023"><span>Mesospheric gravity-<span class="hlt">wave</span> climatology at Adelaide</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Vincent, R. A.</p> <p>1986-01-01</p> <p>The MF Adelaide partial-reflection radar has been operating continuously since November 1983. This has enabled a climatology of gravity-<span class="hlt">wave</span> activity to be constructed for the mesosphere. The data have been analyzed for a medium-period range of 1 to 8 hr. and a longer period range between 8 and 24 hr. covering the inertio-period <span class="hlt">waves</span>. The tidal motions have been filtered out prior to analysis. For the data analyses so far (Nov. 1983 to Dec. 1984), a number of interesting features emerged. Firstly, the <span class="hlt">wave</span> activity at heights above 80 km shows a small seimannual <span class="hlt">variation</span> with season with the activity being strongest in summer and winter. At heights below 80 km however, there is a similar but more marked <span class="hlt">variation</span> with the weakest amplitudes occurring at the time of the changeovers in the prevailing circulation. If breaking gravity <span class="hlt">waves</span> are responsible for much of the turbulence in the mesosphere, then the periods March to April and September to October might also be expected to be periods of weak turbulence. The <span class="hlt">wave</span> field appears to be partially polarized. The meridional amplitudes are larger than the zonal amplitudes, especially in water. It is found that the degree of polarization is about 15% in summer and 30% in winter. The polarized component is found to propagate in the opposite direction to the background flow in the stratosphere, which suggests that the polarization arises through directional filtering of the <span class="hlt">waves</span> as they propagate up from below.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3998816','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3998816"><span>Combining Monte Carlo methods with coherent <span class="hlt">wave</span> optics for the simulation of phase-sensitive X-ray imaging</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Peter, Silvia; Modregger, Peter; Fix, Michael K.; Volken, Werner; Frei, Daniel; Manser, Peter; Stampanoni, Marco</p> <p>2014-01-01</p> <p>Phase-sensitive X-ray imaging shows a high sensitivity towards electron density <span class="hlt">variations</span>, making it well suited for imaging of soft tissue matter. However, there are still open questions about the details of the image formation process. Here, a framework for numerical simulations of phase-sensitive X-ray imaging is presented, which takes both particle- and <span class="hlt">wave</span>-like properties of X-rays into consideration. A split approach is presented where we combine a Monte Carlo method (MC) based sample part with a <span class="hlt">wave</span> optics simulation based propagation part, leading to a framework that takes both particle- and <span class="hlt">wave</span>-like properties into account. The framework can be adapted to different phase-sensitive imaging methods and has been validated through comparisons with experiments for grating interferometry and propagation-based imaging. The validation of the framework shows that the combination of <span class="hlt">wave</span> optics and MC has been successfully implemented and yields good agreement between measurements and simulations. This demonstrates that the physical processes relevant for developing a deeper understanding of scattering in the context of phase-sensitive imaging are modelled in a sufficiently <span class="hlt">accurate</span> manner. The framework can be used for the simulation of phase-sensitive X-ray imaging, for instance for the simulation of grating interferometry or propagation-based imaging. PMID:24763652</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19870011252','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19870011252"><span>Gravity <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fritts, David</p> <p>1987-01-01</p> <p>Gravity <span class="hlt">waves</span> contributed to the establishment of the thermal structure, small scale (80 to 100 km) fluctuations in velocity (50 to 80 m/sec) and density (20 to 30%, 0 to peak). Dominant gravity <span class="hlt">wave</span> spectrum in the middle atmosphere: x-scale, less than 100 km; z-scale, greater than 10 km; t-scale, less than 2 hr. Theorists are beginning to understand middle atmosphere motions. There are two classes: Planetary <span class="hlt">waves</span> and equatorial motions, gravity <span class="hlt">waves</span> and tidal motions. The former give rise to variability at large scales, which may alter apparent mean structure. Effects include density and velocity fluctuations, induced mean motions, and stratospheric warmings which lead to the breakup of the polar vortex and cooling of the mesosphere. On this scale are also equatorial quasi-biennial and semi-annual oscillations. Gravity <span class="hlt">wave</span> and tidal motions produce large rms fluctuations in density and velocity. The magnitude of the density fluctuations compared to the mean density is of the order of the vertical wavelength, which grows with height. Relative density fluctuations are less than, or of the order of 30% below the mesopause. Such motions may cause significant and variable convection, and wind shear. There is a strong seasonal <span class="hlt">variation</span> in gravity <span class="hlt">wave</span> amplitude. Additional observations are needed to address and quantify mean and fluctuation statistics of both density and mean velocity, variability of the mean and fluctuations, and to identify dominant gravity <span class="hlt">wave</span> scales and sources as well as causes of variability, both temporal and geographic.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19990028753','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19990028753"><span>Lamb <span class="hlt">Wave</span> Tomography for Corrosion Mapping</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hinders, Mark K.; McKeon, James C. P.</p> <p>1999-01-01</p> <p>As the world-wide civil aviation fleet continues to age, methods for <span class="hlt">accurately</span> predicting the presence of structural flaws-such as hidden corrosion-that compromise airworthiness become increasingly necessary. Ultrasonic guided <span class="hlt">waves</span>, Lamb <span class="hlt">waves</span>, allow large sections of aircraft structures to be rapidly inspected. However, extracting quantitative information from Lamb <span class="hlt">wave</span> data has always involved highly trained personnel with a detailed knowledge of mechanical-waveguide physics. Our work focuses on using a variety of different tomographic reconstruction techniques to graphically represent the Lamb <span class="hlt">wave</span> data in images that can be easily interpreted by technicians. Because the velocity of Lamb <span class="hlt">waves</span> depends on thickness, we can convert the travel times of the fundamental Lamb modes into a thickness map of the inspection region. In this paper we show results for the identification of single or multiple back-surface corrosion areas in typical aluminum aircraft skin structures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040182464&hterms=inclusion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dinclusion','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040182464&hterms=inclusion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dinclusion"><span>Calculation of the Full Scattering Amplitude without Partial <span class="hlt">Wave</span> Decomposition. 2; Inclusion of Exchange</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shertzer, Janine; Temkin, Aaron</p> <p>2004-01-01</p> <p>The development of a practical method of <span class="hlt">accurately</span> calculating the full scattering amplitude, without making a partial <span class="hlt">wave</span> decomposition is continued. The method is developed in the context of electron-hydrogen scattering, and here exchange is dealt with by considering e-H scattering in the static exchange approximation. The Schroedinger equation in this approximation can be simplified to a set of coupled integro-differential equations. The equations are solved numerically for the full scattering <span class="hlt">wave</span> function. The scattering amplitude can most <span class="hlt">accurately</span> be calculated from an integral expression for the amplitude; that integral can be formally simplified, and then evaluated using the numerically determined <span class="hlt">wave</span> function. The results are essentially identical to converged partial <span class="hlt">wave</span> results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFMOS41B0596T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFMOS41B0596T"><span>Investigation of the relationship between hurricane <span class="hlt">waves</span> and extreme runup</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Thompson, D. M.; Stockdon, H. F.</p> <p>2006-12-01</p> <p>In addition to storm surge, the elevation of <span class="hlt">wave</span>-induced runup plays a significant role in forcing geomorphic change during extreme storms. Empirical formulations for extreme runup, defined as the 2% exceedence level, are dependent on some measure of significant offshore <span class="hlt">wave</span> height. <span class="hlt">Accurate</span> prediction of extreme runup, particularly during hurricanes when <span class="hlt">wave</span> heights are large, depends on selecting the most appropriate measure of <span class="hlt">wave</span> height that provides energy to the nearshore system. Using measurements from deep-water <span class="hlt">wave</span> buoys results in an overprediction of runup elevation. Under storm forcing these large <span class="hlt">waves</span> dissipate across the shelf through friction, whitecapping and depth-limited breaking before reaching the beach and forcing swash processes. The use of a local, shallow water <span class="hlt">wave</span> height has been shown to provide a more <span class="hlt">accurate</span> estimate of extreme runup elevation (Stockdon, et. al. 2006); however, a specific definition of this local <span class="hlt">wave</span> height has yet to be defined. Using observations of nearshore <span class="hlt">waves</span> from the U.S. Army Corps of Engineers' Field Research Facility (FRF) in Duck, NC during Hurricane Isabel, the most relevant measure of <span class="hlt">wave</span> height for use in empirical runup parameterizations was examined. Spatial and temporal variability of the hurricane <span class="hlt">wave</span> field, which made landfall on September 18, 2003, were modeled using SWAN. Comparisons with <span class="hlt">wave</span> data from FRF gages and deep-water buoys operated by NOAA's National Data Buoy Center were used for model calibration. Various measures of local <span class="hlt">wave</span> height (breaking, dissipation-based, etc.) were extracted from the model domain and used as input to the runup parameterizations. Video based observations of runup collected at the FRF during the storm were used to ground truth modeled values. Assessment of the most appropriate measure of <span class="hlt">wave</span> height can be extended over a large area through comparisons to observations of storm- induced geomorphic change.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20208956','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20208956"><span>Discontinuity-free edge-diffraction model for characterization of focused <span class="hlt">wave</span> fields.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sedukhin, Andrey G</p> <p>2010-03-01</p> <p>A model of discontinuity-free edge diffraction is proposed that is valid in the framework of the scalar Debye approximation and describes the formation process and approximate structure of the stationary diffracted field of a monochromatic converging spherical <span class="hlt">wave</span> of limited angular opening throughout the whole space about the focus. The field is represented semianalytically in terms of the sum of a direct quasi-spherical <span class="hlt">wave</span> and two edge quasi-conical <span class="hlt">waves</span> of the zeroth and first order. The angular spectrum amplitudes of all these <span class="hlt">waves</span> have smooth continuous <span class="hlt">variations</span> of the real and imaginary parts in polar angle and radius, the separable nonanalytic functions defining the polar-angle <span class="hlt">variations</span> of the amplitudes being found by optimization techniques.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15857048','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15857048"><span>A full-<span class="hlt">wave</span> Helmholtz model for continuous-<span class="hlt">wave</span> ultrasound transmission.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Huttunen, Tomi; Malinen, Matti; Kaipio, Jari P; White, Phillip Jason; Hynynen, Kullervo</p> <p>2005-03-01</p> <p>A full-<span class="hlt">wave</span> Helmholtz model of continuous-<span class="hlt">wave</span> (CW) ultrasound fields may offer several attractive features over widely used partial-<span class="hlt">wave</span> approximations. For example, many full-<span class="hlt">wave</span> techniques can be easily adjusted for complex geometries, and multiple reflections of sound are automatically taken into account in the model. To date, however, the full-<span class="hlt">wave</span> modeling of CW fields in general 3D geometries has been avoided due to the large computational cost associated with the numerical approximation of the Helmholtz equation. Recent developments in computing capacity together with improvements in finite element type modeling techniques are making possible <span class="hlt">wave</span> simulations in 3D geometries which reach over tens of wavelengths. The aim of this study is to investigate the feasibility of a full-<span class="hlt">wave</span> solution of the 3D Helmholtz equation for modeling of continuous-<span class="hlt">wave</span> ultrasound fields in an inhomogeneous medium. The numerical approximation of the Helmholtz equation is computed using the ultraweak <span class="hlt">variational</span> formulation (UWVF) method. In addition, an inverse problem technique is utilized to reconstruct the velocity distribution on the transducer which is used to model the sound source in the UWVF scheme. The modeling method is verified by comparing simulated and measured fields in the case of transmission of 531 kHz CW fields through layered plastic plates. The comparison shows a reasonable agreement between simulations and measurements at low angles of incidence but, due to mode conversion, the Helmholtz model becomes insufficient for simulating ultrasound fields in plates at large angles of incidence.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/sir/2010/5138/','USGSPUBS'); return false;" href="https://pubs.usgs.gov/sir/2010/5138/"><span>Predicting S-<span class="hlt">wave</span> velocities for unconsolidated sediments at low effective pressure</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Lee, Myung W.</p> <p>2010-01-01</p> <p><span class="hlt">Accurate</span> S-<span class="hlt">wave</span> velocities for shallow sediments are important in performing a reliable elastic inversion for gas hydrate-bearing sediments and in evaluating velocity models for predicting S-<span class="hlt">wave</span> velocities, but few S-<span class="hlt">wave</span> velocities are measured at low effective pressure. Predicting S-<span class="hlt">wave</span> velocities by using conventional methods based on the Biot-Gassmann theory appears to be inaccurate for laboratory-measured velocities at effective pressures less than about 4-5 megapascals (MPa). Measured laboratory and well log velocities show two distinct trends for S-<span class="hlt">wave</span> velocities with respect to P-<span class="hlt">wave</span> velocity: one for the S-<span class="hlt">wave</span> velocity less than about 0.6 kilometer per second (km/s) which approximately corresponds to effective pressure of about 4-5 MPa, and the other for S-<span class="hlt">wave</span> velocities greater than 0.6 km/s. To <span class="hlt">accurately</span> predict S-<span class="hlt">wave</span> velocities at low effective pressure less than about 4-5 MPa, a pressure-dependent parameter that relates the consolidation parameter to shear modulus of the sediments at low effective pressure is proposed. The proposed method in predicting S-<span class="hlt">wave</span> velocity at low effective pressure worked well for velocities of water-saturated sands measured in the laboratory. However, this method underestimates the well-log S-<span class="hlt">wave</span> velocities measured in the Gulf of Mexico, whereas the conventional method performs well for the well log velocities. The P-<span class="hlt">wave</span> velocity dispersion due to fluid in the pore spaces, which is more pronounced at high frequency with low effective pressures less than about 4 MPa, is probably a cause for this discrepancy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018GeoJI.213..169K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018GeoJI.213..169K"><span>Eliminating time dispersion from seismic <span class="hlt">wave</span> modeling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koene, Erik F. M.; Robertsson, Johan O. A.; Broggini, Filippo; Andersson, Fredrik</p> <p>2018-04-01</p> <p>We derive an expression for the error introduced by the second-order <span class="hlt">accurate</span> temporal finite-difference (FD) operator, as present in the FD, pseudospectral and spectral element methods for seismic <span class="hlt">wave</span> modeling applied to time-invariant media. The `time-dispersion' error speeds up the signal as a function of frequency and time step only. Time dispersion is thus independent of the propagation path, medium or spatial modeling error. We derive two transforms to either add or remove time dispersion from synthetic seismograms after a simulation. The transforms are compared to previous related work and demonstrated on <span class="hlt">wave</span> modeling in acoustic as well as elastic media. In addition, an application to imaging is shown. The transforms enable <span class="hlt">accurate</span> computation of synthetic seismograms at reduced cost, benefitting modeling applications in both exploration and global seismology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMDI31A0395H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMDI31A0395H"><span>Topography Estimation of the Core Mantle Boundary with ScS Reverberations and Diffraction <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hein, B. E.; Nakata, N.</p> <p>2017-12-01</p> <p>In this study, we use the propagation of global seismic <span class="hlt">waves</span> to study the Core Mantle Boundary (CMB). We focus on the use of S-<span class="hlt">wave</span> reflections at the CMB (ScS reverberations) and outer-core diffracted <span class="hlt">waves</span>. It is difficult imaging the CMB with the ScS <span class="hlt">wave</span> because the complexity of the structure in the near surface ( 50 km); the complex structure degrades the signal-to-noise ratio of of the ScS. To avoid estimating the structure in the crust, we rely on the concept of seismic interferometry to extract <span class="hlt">wave</span> propagation through mantle, but not through the crust. Our approach is compute the deconvolution between the ScS (and its reverberation) and direct S <span class="hlt">waves</span> generated by intermediate to deep earthquakes (>50 km depth). Through this deconvolution, we have the ability to filter out the direct S <span class="hlt">wave</span> and retrieve the <span class="hlt">wave</span> field propagating from only the hypocenter to the outer core, but not between the hypocenter to the receiver. After the deconvolution, we can isolate the CMB reflected <span class="hlt">waves</span> from the complicated <span class="hlt">wave</span> phenomena because of the near-surface structure. Utilizing intermediate and deep earthquakes is key since we can suppress the near-surface effect from the surface to the hypocenter of the earthquakes. The <span class="hlt">variation</span> of such <span class="hlt">waves</span> (e.g., travel-time perturbation and/or wavefield decorrelation) at different receivers and earthquakes provides the information of the topography of the CMB. In order to get a more detailed image of the topography of the CMB we use diffracted seismic <span class="hlt">waves</span> such as Pdiff , Sdiff, and P'P'. By using two intermediate to deep earthquakes on a great circle path with a station we can extract the <span class="hlt">wave</span> propagation between the two earthquakes to simplify the waveform, similar to how it is preformed using the ScS <span class="hlt">wave</span>. We generate more illumination of the CMB by using diffracted <span class="hlt">waves</span> rather than only using ScS reverberations. The <span class="hlt">accurate</span> topography of CMB obtained by these deconvolution analyses may provide new insight of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016cosp...41E.775G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016cosp...41E.775G"><span>Decomposing <span class="hlt">variations</span> of geopotential height in the troposphere and stratosphere into stationary and travelling <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guryanov, Vladimir; Eliseev, Alexey</p> <p>2016-07-01</p> <p>The ERA-Interim geopotential height in the Northern Hemisphere from November to March, 1992-2015 in the layer from between pressure levels 1000 mb and 1 mb is expanded into stationary and travelling zonal <span class="hlt">waves</span> with zonal wavenumbers, k, from 1 to 10, and with periods, T, from 2 to 156 days (the so called Hayashi spectra). Among the studied <span class="hlt">waves</span>, the largest amplitude is attained by the stationary and travelling <span class="hlt">waves</span> with zonal wavenumber k=1 and with periods from 3 to 4 weeks in the upper stratosphere over the latitudinal belt 60-70oN. The stationary <span class="hlt">waves</span> with k from 1 to 3 and with T from 2 to 3 weeks are most pronounced in the stratosphere. In turn, the largest amplitudes of the travelling <span class="hlt">waves</span> with zonal wavenumbers k ≥ 5 are found in the troposphere. The dominant periods of the latter <span class="hlt">waves</span> are about 1 week or slightly higher, and this dominant period basically decrease with increasing wavenumber. In the upper stratosphere, the eastward travelling <span class="hlt">waves</span> generally dominate over westward ones. The only exception is the longest zonal mode with k=1, for which the amplitude of the westward travelling <span class="hlt">wave</span> is larger than that for the eastward one. The period of the travelling <span class="hlt">waves</span> dominating in the upper stratosphere is close to 3 weeks. In the upper troposphere, the amplitudes of the eastward <span class="hlt">waves</span> with k from 4 to 10 is several-fold larger than those for their westward counterparts. The latter is reflected in the larger average wavenumber of the eastward travelling <span class="hlt">wave</span> in comparison to that of the westarward one. The period of the gravest of the dominant travelling <span class="hlt">waves</span> in the upper troposphere is close to one week, and it decreases to 2-4 days for the dominant travelling <span class="hlt">waves</span> with k=8-10.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhDT........18M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhDT........18M"><span>Simulations of Magnetohydrodynamic <span class="hlt">Waves</span> Driven by Photospheric Motions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mumford, Stuart</p> <p>2016-04-01</p> <p> the quantification of the relative strengths of excited modes. The torsional drivers primarily excite Alfvén modes (≈ 60 %) of the total flux) with contributions from the slow mode. The horizontal and vertical drivers primarily excite slow and fast modes respectively, with small <span class="hlt">variations</span> dependent upon flux surface radius. This analysis is then applied to more in depth studies of the logarithmic spiral driver. Firstly, five different values for the (B_L) spiral expansion factor are chosen which control how rapidly the spiral expands. Larger values of (B_L) make the driving profile more radial. The results of this analysis show that the Alfvén <span class="hlt">wave</span> is the dominant <span class="hlt">wave</span> for lower values of the expansion factor, whereas, for the higher values the parallel component is dominant. This transition occurs within the range of the observational constraints, demonstrating that under realistic conditions spiral drivers may not excite most of their <span class="hlt">wave</span> flux in the Alfvén mode. Finally, the logarithmic spiral is further studied, but with a variety of different periods. Ten periods from 30 to 300 seconds are chosen, and the simulations are again analysed using the flux surface method employed previously. The results of this study are minimal <span class="hlt">variation</span> in the percentage <span class="hlt">wave</span> flux in each mode, with no more than 20 % <span class="hlt">variation</span> in any mode for any flux surface studied. Within this small <span class="hlt">variation</span>, some non-linear changes in the <span class="hlt">wave</span> flux were observed, especially around the more important small periods. Due to the short life time of the MBPs it is thought the short period <span class="hlt">waves</span> would have more effect and therefore this non-linear <span class="hlt">variation</span> in <span class="hlt">wave</span> flux could have some impact on the modes present in the solar atmosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19810060806&hterms=surface+density&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dsurface%2Bdensity','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19810060806&hterms=surface+density&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dsurface%2Bdensity"><span>Density <span class="hlt">waves</span> in Saturn's rings</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cuzzi, J. N.; Lissauer, J. J.; Shu, F. H.</p> <p>1981-01-01</p> <p>Certain radial brightness <span class="hlt">variations</span> in the outer Cassini division of Saturn's rings may be spiral density <span class="hlt">waves</span> driven by Saturn's large moon Iapetus, in which case a value of approximately 16 g/sq cm for the surface density is calculated in the region where the <span class="hlt">waves</span> are seen. The kinematic viscosity in the same region is approximately 170 sq cm/s and the vertical scale height of the ring is estimated to be a maximum of approximately 40 m.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AIPC.1793j0030K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AIPC.1793j0030K"><span>Evolutions of elastic-plastic shock compression <span class="hlt">waves</span> in different materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kanel, G. I.; Zaretsky, E. B.; Razorenov, S. V.; Savinykh, A. S.; Garkushin, G. V.</p> <p>2017-01-01</p> <p>In the paper, we discuss such unexpected features in the <span class="hlt">wave</span> evolution in solids as a departure from self-similar development of the <span class="hlt">wave</span> process which is accompanied with apparent sub-sonic <span class="hlt">wave</span> propagation, changes of shape of elastic precursor <span class="hlt">wave</span> as a result of <span class="hlt">variations</span> in the material structure and the temperature, unexpected peculiarities of reflection of elastic-plastic <span class="hlt">waves</span> from free surface, effects of internal friction at shock compression of glasses and some other effects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012PhPro..37...43A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012PhPro..37...43A"><span><span class="hlt">Accurate</span> Measurement of Velocity and Acceleration of Seismic Vibrations near Nuclear Power Plants</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arif, Syed Javed; Imdadullah; Asghar, Mohammad Syed Jamil</p> <p></p> <p>In spite of all prerequisite geological study based precautions, the sites of nuclear power plants are also susceptible to seismic vibrations and their consequent effects. The effect of the ongoing nuclear tragedy in Japan caused by an earthquake and its consequent tsunami on March 11, 2011 is currently beyond contemplations. It has led to a rethinking on nuclear power stations by various governments around the world. Therefore, the prediction of location and time of large earthquakes has regained a great importance. The earth crust is made up of several wide, thin and rigid plates like blocks which are in constant motion with respect to each other. A series of vibrations on the earth surface are produced by the generation of elastic seismic <span class="hlt">waves</span> due to sudden rupture within the plates during the release of accumulated strain energy. The range of frequency of seismic vibrations is from 0 to 10 Hz. However, there appears a large <span class="hlt">variation</span> in magnitude, velocity and acceleration of these vibrations. The response of existing or conventional methods of measurement of seismic vibrations is very slow, which is of the order of tens of seconds. A systematic and high resolution measurement of velocity and acceleration of these vibrations are useful to interpret the pattern of <span class="hlt">waves</span> and their anomalies more <span class="hlt">accurately</span>, which are useful for the prediction of an earthquake. In the proposed work, a fast rotating magnetic field (RMF) is used to measure the velocity and acceleration of seismic vibrations in the millisecond range. The broad spectrum of pulses within one second range, measured by proposed method, gives all possible values of instantaneous velocity and instantaneous acceleration of the seismic vibrations. The spectrum of pulses in millisecond range becomes available which is useful to measure the pattern of fore shocks to predict the time and location of large earthquakes more <span class="hlt">accurately</span>. Moreover, instead of average, the peak values of these quantities are helpful</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.5951F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.5951F"><span>Validation of a <span class="hlt">Wave</span> Data Assimilation System Based on SWAN</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Flampourisi, Stylianos; Veeramony, Jayaram; Orzech, Mark D.; Ngodock, Hans E.</p> <p>2013-04-01</p> <p>SWAN is one of the most broadly used models for <span class="hlt">wave</span> predictions in the nearshore, with known and extensively studied limitations due to the physics and/or to the numerical implementation. In order to improve the performance of the model, a 4DVAR data assimilation system based on a tangent linear code and the corresponding adjoint from the numerical SWAN model has been developed at NRL(Orzech et. al., 2013), by implementing the methodology of Bennett 2002. The assimilation system takes into account the nonlinear triad and quadruplet interactions, depth-limited breaking, wind forcing, bottom friction and white-capping. Using conjugate gradient method, the assimilation system minimizes a quadratic penalty functional (which represents the overall error of the simulation) and generates the correction of the forward simulation in spatial, temporal and spectral domain. The weights are given to the output of the adjoint by calculating the covariance to an ensemble of forward simulations according to Evensen 2009. This presentation will focus on the extension of the system to a weak-constrainted data assimilation system and on the extensive validation of the system by using <span class="hlt">wave</span> spectra for forcing, assimilation and validation, from FRF Duck, North Carolina, during August 2011. During this period, at the 17 m waverider buoy location, the wind speed was up to 35 m/s (due to Hurricane Irene) and the significant <span class="hlt">wave</span> height varied from 0.5 m to 6 m and the peak period between 5 s and 18 s. In general, this study shows significant improvement of the integrated spectral properties, but the main benefit of assimilating the <span class="hlt">wave</span> spectra (and not only their integrated properties) is that the <span class="hlt">accurate</span> simulation of separated, in frequency and in direction, <span class="hlt">wave</span> systems is possible even nearshore, where non-linear phenomena are dominant. The system is ready to be used for more precise reanalysis of the <span class="hlt">wave</span> climate and climate variability, and determination of coastal hazards in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004SPIE.5273..341O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004SPIE.5273..341O"><span>Z-scan theoretical and experimental studies for <span class="hlt">accurate</span> measurements of the nonlinear refractive index and absorption of optical glasses near damage threshold</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Olivier, Thomas; Billard, Franck; Akhouayri, Hassan</p> <p>2004-06-01</p> <p>Self-focusing is one of the dramatic phenomena that may occur during the propagation of a high power laser beam in a nonlinear material. This phenomenon leads to a degradation of the <span class="hlt">wave</span> front and may also lead to a photoinduced damage of the material. Realistic simulations of the propagation of high power laser beams require an <span class="hlt">accurate</span> knowledge of the nonlinear refractive index γ. In the particular case of fused silica and in the nanosecond regime, it seems that electronic mechanisms as well as electrostriction and thermal effects can lead to a significant refractive index <span class="hlt">variation</span>. Compared to the different methods used to measure this parmeter, the Z-scan method is simple, offers a good sensitivity and may give absolute measurements if the incident beam is <span class="hlt">accurately</span> studied. However, this method requires a very good knowledge of the incident beam and of its propagation inside a nonlinear sample. We used a split-step propagation algorithm to simlate Z-scan curves for arbitrary beam shape, sample thickness and nonlinear phase shift. According to our simulations and a rigorous analysis of the Z-scan measured signal, it appears that some abusive approximations lead to very important errors. Thus, by reducing possible errors on the interpretation of Z-scan experimental studies, we performed <span class="hlt">accurate</span> measurements of the nonlinear refractive index of fused silica that show the significant contribution of nanosecond mechanisms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20020070844','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20020070844"><span>Interseasonal <span class="hlt">Variations</span> in the Middle Atmosphere Forced by Gravity <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mayr, H. G.; Mengel, J. G.; Drob, D. P.; Porter, H. S.; Chan, K. L.; Bhartia, P. K. (Technical Monitor)</p> <p>2002-01-01</p> <p>In our Numerical Spectral Model (NSM), which incorporates Hines' Doppler Spread Parameterization, gravity <span class="hlt">waves</span> (GW) propagating in the east/west direction can generate the essential features of the observed equatorial oscillations in the zonal circulation and in particular the QBO (quasi-biennial oscillation) extending from the stratosphere into the upper mesosphere. We report here that the NSM also produces inter-seasonal <span class="hlt">variations</span> in the zonally symmetric (m = 0) meridional circulation. A distinct but variable meridional wind oscillation (MWO) is generated, which appears to be the counterpart to the QBO. With a vertical grid-point resolution of about 0.5 km, the NSM produces the MWO through momentum deposition of GWs propagating in the north/south direction. The resulting momentum source represents a third (generally odd) order non-linear function of the meridional winds, and this enables the oscillation, as in the case of the QBO for the zonal winds. Since the meridional winds are relatively small compared to the zonal winds, however, the vertical wavelength that maintains the MWO is much smaller, i.e., only about 10 km instead of 40 km for the QBO. Consistent with the associated increase of the viscous stress, the period of the MWO is then short compared with that of the QBO, i.e., only about two to four months. Depending on the strength of the GW forcing, the computed amplitudes of the MWO are typically 4 m/s in the upper stratosphere and mesosphere, and the associated temperature amplitudes are between about 2 and 3 K. These amplitudes may be observable with the instruments on the TIMED spacecraft. Extended computer simulations with the NSM in 2D (two-dimensional) and 3D (three-dimensional) reveal that the MWO is modulated by and in turn influences the QBO.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMNS31A1935S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMNS31A1935S"><span>Inversion of Surface-<span class="hlt">wave</span> Dispersion Curves due to Low-velocity-layer Models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shen, C.; Xia, J.; Mi, B.</p> <p>2016-12-01</p> <p>A successful inversion relies on exact forward modeling methods. It is a key step to <span class="hlt">accurately</span> calculate multi-mode dispersion curves of a given model in high-frequency surface-<span class="hlt">wave</span> (Rayleigh <span class="hlt">wave</span> and Love <span class="hlt">wave</span>) methods. For normal models (shear (S)-<span class="hlt">wave</span> velocity increasing with depth), their theoretical dispersion curves completely match the dispersion spectrum that is generated based on <span class="hlt">wave</span> equation. For models containing a low-velocity-layer, however, phase velocities calculated by existing forward-modeling algorithms (e.g. Thomson-Haskell algorithm, Knopoff algorithm, fast vector-transfer algorithm and so on) fail to be consistent with the dispersion spectrum at a high frequency range. They will approach a value that close to the surface-<span class="hlt">wave</span> velocity of the low-velocity-layer under the surface layer, rather than that of the surface layer when their corresponding wavelengths are short enough. This phenomenon conflicts with the characteristics of surface <span class="hlt">waves</span>, which results in an erroneous inverted model. By comparing the theoretical dispersion curves with simulated dispersion energy, we proposed a direct and essential solution to <span class="hlt">accurately</span> compute surface-<span class="hlt">wave</span> phase velocities due to low-velocity-layer models. Based on the proposed forward modeling technique, we can achieve correct inversion for these types of models. Several synthetic data proved the effectiveness of our method.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14995022','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14995022"><span>A new point contact surface acoustic <span class="hlt">wave</span> transducer for measurement of acoustoelastic effect of polymethylmethacrylate.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lee, Yung-Chun; Kuo, Shi Hoa</p> <p>2004-01-01</p> <p>A new acoustic transducer and measurement method have been developed for precise measurement of surface <span class="hlt">wave</span> velocity. This measurement method is used to investigate the acoustoelastic effects for <span class="hlt">waves</span> propagating on the surface of a polymethylmethacrylate (PMMA) sample. The transducer uses two miniature conical PZT elements for acoustic <span class="hlt">wave</span> transmitter and receiver on the sample surface; hence, it can be viewed as a point-source/point-receiver transducer. Acoustic <span class="hlt">waves</span> are excited and detected with the PZT elements, and the <span class="hlt">wave</span> velocity can be <span class="hlt">accurately</span> determined with a cross-correlation waveform comparison method. The transducer and its measurement method are particularly sensitive and <span class="hlt">accurate</span> in determining small changes in <span class="hlt">wave</span> velocity; therefore, they are applied to the measurement of acoustoelastic effects in PMMA materials. Both the surface skimming longitudinal <span class="hlt">wave</span> and Rayleigh surface <span class="hlt">wave</span> can be simultaneously excited and measured. With a uniaxial-loaded PMMA sample, both acoustoelastic effects for surface skimming longitudinal <span class="hlt">wave</span> and Rayleigh <span class="hlt">waves</span> of PMMA are measured. The acoustoelastic coefficients for both types of surface <span class="hlt">wave</span> motions are simultaneously determined. The transducer and its measurement method provide a practical way for measuring surface stresses nondestructively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018E%26ES..140a2120I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018E%26ES..140a2120I"><span><span class="hlt">Variation</span> of Time Domain Failure Probabilities of Jack-up with <span class="hlt">Wave</span> Return Periods</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Idris, Ahmad; Harahap, Indra S. H.; Ali, Montassir Osman Ahmed</p> <p>2018-04-01</p> <p>This study evaluated failure probabilities of jack up units on the framework of time dependent reliability analysis using uncertainty from different sea states representing different return period of the design <span class="hlt">wave</span>. Surface elevation for each sea state was represented by Karhunen-Loeve expansion method using the eigenfunctions of prolate spheroidal <span class="hlt">wave</span> functions in order to obtain the <span class="hlt">wave</span> load. The stochastic <span class="hlt">wave</span> load was propagated on a simplified jack up model developed in commercial software to obtain the structural response due to the <span class="hlt">wave</span> loading. Analysis of the stochastic response to determine the failure probability in excessive deck displacement in the framework of time dependent reliability analysis was performed by developing Matlab codes in a personal computer. Results from the study indicated that the failure probability increases with increase in the severity of the sea state representing a longer return period. Although the results obtained are in agreement with the results of a study of similar jack up model using time independent method at higher values of maximum allowable deck displacement, it is in contrast at lower values of the criteria where the study reported that failure probability decreases with increase in the severity of the sea state.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA266384','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA266384"><span>Observations and Modelling of Winds and <span class="hlt">Waves</span> during the Surface <span class="hlt">Wave</span> Dynamics Experiment. Report 1. Intensive Observation Period IOP-1, 20-31 October 1990</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1993-04-01</p> <p><span class="hlt">wave</span> buoy provided by SEATEX, Norway (Figure 3). The modified Mills-cross array was designed to provide spatial estimates of the <span class="hlt">variation</span> in <span class="hlt">wave</span>, wind... designed for SWADE to examine the <span class="hlt">wave</span> physics at different spatial and temporal scales, and the usefulness of a nested system. Each grid is supposed to...field specification. SWADE Model This high-resolution grid was designed to simulate the small scale <span class="hlt">wave</span> physics and to improve and verify the source</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870040886&hterms=function+wave&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dfunction%2Bwave','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870040886&hterms=function+wave&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dfunction%2Bwave"><span><span class="hlt">Variational</span> divergence in <span class="hlt">wave</span> scattering theory with Kirchhoffean trial functions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bird, J. F.</p> <p>1986-01-01</p> <p>In a recent study of <span class="hlt">variational</span> improvement of the Kirchhoff approximation for electromagnetic scattering by rough surfaces, a key ingredient in the <span class="hlt">variational</span> principle was found to diverge for important configurations (e.g., backscatter) if the polarization had any vertical component. The cause and a cure of this divergence are discussed here. The divergence is demonstrated to occur for arbitrary perfectly conducting scatterers and its universal characterstics are determined, by means of a general divergence criterion that is derived. A <span class="hlt">variational</span> cure for the divergence is prescribed, and it is tested successfully on a standard scattering model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.9565M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.9565M"><span>Gravity <span class="hlt">waves</span> produced by the total solar eclipse of 1 August 2008</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marty, Julien; Francis, Dalaudier; Damien, Ponceau; Elisabeth, Blanc; Ulziibat, Munkhuu</p> <p>2010-05-01</p> <p>Gravity <span class="hlt">waves</span> are a major component of atmospheric small scale dynamics because of their ability to transport energy and momentum over considerable distances and of their interactions with the mean circulation or other <span class="hlt">waves</span>. They produce pressure <span class="hlt">variations</span> which can be detected at the ground by microbarographs. The solar intensity reduction which occurs in the atmosphere during solar eclipses is known to act as a temporary source of large scale gravity <span class="hlt">waves</span>. Despite decades of research, observational evidence for a characteristic bow-<span class="hlt">wave</span> response of the atmosphere to eclipse passages remains elusive. A new versatile numerical model (Marty, J. and Dalaudier, F.: Linear spectral numerical model for internal gravity <span class="hlt">wave</span> propagation. J. Atmos. Sci. (in press)) is presented and applied to the cooling of the atmosphere during a solar eclipse. Calculated solutions appear to be in good agreement with ground pressure fluctuations recorded during the total solar eclipse of 1 August 2008. To the knowledge of the authors, this is the first time that such a result is presented. A three-dimensional linear spectral numerical model is used to propagate internal gravity <span class="hlt">wave</span> fluctuations in a stably stratified atmosphere. The model is developed to get first-order estimations of gravity <span class="hlt">wave</span> fluctuations produced by identified sources. It is based on the solutions of the linearized fundamental fluid equations and uses the fully-compressible dispersion relation for inertia-gravity <span class="hlt">waves</span>. The spectral implementation excludes situations involving spatial <span class="hlt">variations</span> of buoyancy frequency or background wind. However density stratification <span class="hlt">variations</span> are taken into account in the calculation of fluctuation amplitudes. In addition to gravity <span class="hlt">wave</span> packet free propagation, the model handles both impulsive and continuous sources. It can account for spatial and temporal <span class="hlt">variations</span> of the sources allowing to cover a broad range of physical situations. It is applied to the case of solar</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017APS..DFDA19001S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..DFDA19001S"><span>Capillary <span class="hlt">waves</span> with surface viscosity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shen, Li; Denner, Fabian; Morgan, Neal; van Wachem, Berend; Dini, Daniele</p> <p>2017-11-01</p> <p>Experiments over the last 50 years have suggested a correlation between the surface (shear) viscosity and the stability of a foam or emulsion. With recent techniques allowing more <span class="hlt">accurate</span> measurements of the elusive surface viscosity, we examine this link theoretically using small-amplitude capillary <span class="hlt">waves</span> in the presence of the Marangoni effect and surface viscosity modelled via the Boussinesq-Scriven model. The surface viscosity effect is found to contribute a damping effect on the amplitude of the capillary <span class="hlt">wave</span> with subtle differences to the effect of the convective-diffusive Marangoni transport. The general <span class="hlt">wave</span> dispersion is augmented to take into account the Marangoni and surface viscosity effects, and a first-order correction to the critical damping wavelength is derived. The authors acknowledge the financial support of the Shell University Technology Centre for fuels and lubricants.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010IEITE..91..968Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010IEITE..91..968Y"><span><span class="hlt">Accurate</span> Modeling Method for Cu Interconnect</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yamada, Kenta; Kitahara, Hiroshi; Asai, Yoshihiko; Sakamoto, Hideo; Okada, Norio; Yasuda, Makoto; Oda, Noriaki; Sakurai, Michio; Hiroi, Masayuki; Takewaki, Toshiyuki; Ohnishi, Sadayuki; Iguchi, Manabu; Minda, Hiroyasu; Suzuki, Mieko</p> <p></p> <p>This paper proposes an <span class="hlt">accurate</span> modeling method of the copper interconnect cross-section in which the width and thickness dependence on layout patterns and density caused by processes (CMP, etching, sputtering, lithography, and so on) are fully, incorporated and universally expressed. In addition, we have developed specific test patterns for the model parameters extraction, and an efficient extraction flow. We have extracted the model parameters for 0.15μm CMOS using this method and confirmed that 10%τpd error normally observed with conventional LPE (Layout Parameters Extraction) was completely dissolved. Moreover, it is verified that the model can be applied to more advanced technologies (90nm, 65nm and 55nm CMOS). Since the interconnect delay <span class="hlt">variations</span> due to the processes constitute a significant part of what have conventionally been treated as random <span class="hlt">variations</span>, use of the proposed model could enable one to greatly narrow the guardbands required to guarantee a desired yield, thereby facilitating design closure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA534986','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA534986"><span><span class="hlt">Accurate</span> Modeling of Ionospheric Electromagnetic Fields Generated by a Low Altitude VLF Transmitter</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2009-03-31</p> <p>AFRL-RV-HA-TR-2009-1055 <span class="hlt">Accurate</span> Modeling of Ionospheric Electromagnetic Fields Generated by a Low Altitude VLF Transmitter ...m (or even 500 m) at mid to high latitudes . At low latitudes , the FDTD model exhibits <span class="hlt">variations</span> that make it difficult to determine a reliable...Scientific, Final 3. DATES COVERED (From - To) 02-08-2006 – 31-12-2008 4. TITLE AND SUBTITLE <span class="hlt">Accurate</span> Modeling of Ionospheric Electromagnetic Fields</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910068898&hterms=foreshock&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dforeshock','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910068898&hterms=foreshock&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dforeshock"><span><span class="hlt">Variations</span> in plasma <span class="hlt">wave</span> intensity with distance along the electron foreshock boundary at Venus</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Crawford, G. K.; Strangeway, R. J.; Russell, C. T.</p> <p>1991-01-01</p> <p>Plasma <span class="hlt">waves</span> are observed in the solar wind upstream of the Venus bow shock by the Pioneer Venus Orbiter. These <span class="hlt">wave</span> signatures occur during periods when the interplanetary magnetic field through the spacecraft position intersects the bow shock, thereby placing the spacecraft in the foreshock region. <span class="hlt">Wave</span> intensity is analyzed as a function of distance along the electron foreshock boundary. It is found that the peak <span class="hlt">wave</span> intensity may increase along the foreshock boundary from the tangent point to a maximum value at several Venus radii, then decrease in intensity with subsequent increase in distance. These observations could be associated with the instability process: the instability of the distribution function increasing with distance from the tangent point to saturation at the peak. Thermalization of the beam for distances beyond this point could reduce the distribution function instability resulting in weaker <span class="hlt">wave</span> signatures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28484326','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28484326"><span><span class="hlt">Wave</span> directional spreading from point field measurements.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>McAllister, M L; Venugopal, V; Borthwick, A G L</p> <p>2017-04-01</p> <p>Ocean <span class="hlt">waves</span> have multidirectional components. Most <span class="hlt">wave</span> measurements are taken at a single point, and so fail to capture information about the relative directions of the <span class="hlt">wave</span> components directly. Conventional means of directional estimation require a minimum of three concurrent time series of measurements at different spatial locations in order to derive information on local directional <span class="hlt">wave</span> spreading. Here, the relationship between <span class="hlt">wave</span> nonlinearity and directionality is utilized to estimate local spreading without the need for multiple concurrent measurements, following Adcock & Taylor (Adcock & Taylor 2009 Proc. R. Soc. A 465 , 3361-3381. (doi:10.1098/rspa.2009.0031)), with the assumption that directional spreading is frequency independent. The method is applied to measurements recorded at the North Alwyn platform in the northern North Sea, and the results compared against estimates of <span class="hlt">wave</span> spreading by conventional measurement methods and hindcast data. Records containing freak <span class="hlt">waves</span> were excluded. It is found that the method provides <span class="hlt">accurate</span> estimates of <span class="hlt">wave</span> spreading over a range of conditions experienced at North Alwyn, despite the noisy chaotic signals that characterize such ocean <span class="hlt">wave</span> data. The results provide further confirmation that Adcock and Taylor's method is applicable to metocean data and has considerable future promise as a technique to recover estimates of <span class="hlt">wave</span> spreading from single point <span class="hlt">wave</span> measurement devices.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20000115617','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20000115617"><span>Mesosphere Dynamics with Gravity <span class="hlt">Wave</span> Forcing. 1; Diurnal and Semi-Diurnal Tides</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mayr, H. G.; Mengel, J. G.; Chan, K. L.; Porter, H. S.; Einaudi, Franco (Technical Monitor)</p> <p>2000-01-01</p> <p>We present results from a nonlinear, 3D, time dependent numerical spectral model (NSM), which extends from the ground up into the thermosphere and incorporates Hines' Doppler Spread Parameterization for small-scale gravity <span class="hlt">waves</span> (GW). Our focal point is the mesosphere that is dominated by <span class="hlt">wave</span> interactions. We discuss diurnal and semi-diurnal tides ill the present paper (Part 1) and planetary <span class="hlt">waves</span> in the companion paper (Part 2). To provide an understanding of the seasonal <span class="hlt">variations</span> of tides, in particular with regard to gravity <span class="hlt">wave</span> processes, numerical experiments are performed that lead to the following conclusions: 1. The large semiannual <span class="hlt">variations</span> in tile diurnal tide (DT), with peak amplitudes observed around equinox, are produced primarily by GW interactions that involve, in part, planetary <span class="hlt">waves</span>. 2. The DT, like planetary <span class="hlt">waves</span>, tends to be amplified by GW momentum deposition, which reduces also the vertical wavelength. 3.<span class="hlt">Variations</span> in eddy viscosity associated with GW interactions tend to peak in late spring and early fall and call also influence the DT. 4. The semidiurnal semidiurnal tide (SDT), and its phase in particular, is strongly influenced by the mean zonal circulation. 5. The SDT, individually, is amplified by GW's. But the DT filters out GW's such that the <span class="hlt">wave</span> interaction effectively reduces the amplitude of the SDT, effectively producing a strong nonlinear interaction between the DT and SDT. 6.) Planetary <span class="hlt">waves</span> generated internally by baroclinic instability and GW interaction produce large amplitude modulations of the DT and SDT.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ApGeo..15..118W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ApGeo..15..118W"><span>Automatic pickup of arrival time of channel <span class="hlt">wave</span> based on multi-channel constraints</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Bao-Li</p> <p>2018-03-01</p> <p><span class="hlt">Accurately</span> detecting the arrival time of a channel <span class="hlt">wave</span> in a coal seam is very important for in-seam seismic data processing. The arrival time greatly affects the accuracy of the channel <span class="hlt">wave</span> inversion and the computed tomography (CT) result. However, because the signal-to-noise ratio of in-seam seismic data is reduced by the long wavelength and strong frequency dispersion, <span class="hlt">accurately</span> timing the arrival of channel <span class="hlt">waves</span> is extremely difficult. For this purpose, we propose a method that automatically picks up the arrival time of channel <span class="hlt">waves</span> based on multi-channel constraints. We first estimate the Jaccard similarity coefficient of two ray paths, then apply it as a weight coefficient for stacking the multichannel dispersion spectra. The reasonableness and effectiveness of the proposed method is verified in an actual data application. Most importantly, the method increases the degree of automation and the pickup precision of the channel-<span class="hlt">wave</span> arrival time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19900019364','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19900019364"><span><span class="hlt">Accurate</span> quantum chemical calculations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Taylor, Peter R.</p> <p>1989-01-01</p> <p>An important goal of quantum chemical calculations is to provide an understanding of chemical bonding and molecular electronic structure. A second goal, the prediction of energy differences to chemical accuracy, has been much harder to attain. First, the computational resources required to achieve such accuracy are very large, and second, it is not straightforward to demonstrate that an apparently <span class="hlt">accurate</span> result, in terms of agreement with experiment, does not result from a cancellation of errors. Recent advances in electronic structure methodology, coupled with the power of vector supercomputers, have made it possible to solve a number of electronic structure problems exactly using the full configuration interaction (FCI) method within a subspace of the complete Hilbert space. These exact results can be used to benchmark approximate techniques that are applicable to a wider range of chemical and physical problems. The methodology of many-electron quantum chemistry is reviewed. Methods are considered in detail for performing FCI calculations. The application of FCI methods to several three-electron problems in molecular physics are discussed. A number of benchmark applications of FCI <span class="hlt">wave</span> functions are described. Atomic basis sets and the development of improved methods for handling very large basis sets are discussed: these are then applied to a number of chemical and spectroscopic problems; to transition metals; and to problems involving potential energy surfaces. Although the experiences described give considerable grounds for optimism about the general ability to perform <span class="hlt">accurate</span> calculations, there are several problems that have proved less tractable, at least with current computer resources, and these and possible solutions are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950027384','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950027384"><span><span class="hlt">Accurate</span> estimation of sigma(exp 0) using AIRSAR data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Holecz, Francesco; Rignot, Eric</p> <p>1995-01-01</p> <p>During recent years signature analysis, classification, and modeling of Synthetic Aperture Radar (SAR) data as well as estimation of geophysical parameters from SAR data have received a great deal of interest. An important requirement for the quantitative use of SAR data is the <span class="hlt">accurate</span> estimation of the backscattering coefficient sigma(exp 0). In terrain with relief <span class="hlt">variations</span> radar signals are distorted due to the projection of the scene topography into the slant range-Doppler plane. The effect of these <span class="hlt">variations</span> is to change the physical size of the scattering area, leading to errors in the radar backscatter values and incidence angle. For this reason the local incidence angle, derived from sensor position and Digital Elevation Model (DEM) data must always be considered. Especially in the airborne case, the antenna gain pattern can be an additional source of radiometric error, because the radar look angle is not known precisely as a result of the the aircraft motions and the local surface topography. Consequently, radiometric distortions due to the antenna gain pattern must also be corrected for each resolution cell, by taking into account aircraft displacements (position and attitude) and position of the backscatter element, defined by the DEM data. In this paper, a method to derive an <span class="hlt">accurate</span> estimation of the backscattering coefficient using NASA/JPL AIRSAR data is presented. The results are evaluated in terms of geometric accuracy, radiometric <span class="hlt">variations</span> of sigma(exp 0), and precision of the estimated forest biomass.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4466592','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4466592"><span>Analytic descriptions of cylindrical electromagnetic <span class="hlt">waves</span> in a nonlinear medium</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Xiong, Hao; Si, Liu-Gang; Yang, Xiaoxue; Wu, Ying</p> <p>2015-01-01</p> <p>A simple but highly efficient approach for dealing with the problem of cylindrical electromagnetic <span class="hlt">waves</span> propagation in a nonlinear medium is proposed based on an exact solution proposed recently. We derive an analytical explicit formula, which exhibiting rich interesting nonlinear effects, to describe the propagation of any amount of cylindrical electromagnetic <span class="hlt">waves</span> in a nonlinear medium. The results obtained by using the present method are <span class="hlt">accurately</span> concordant with the results of using traditional coupled-<span class="hlt">wave</span> equations. As an example of application, we discuss how a third <span class="hlt">wave</span> affects the sum- and difference-frequency generation of two <span class="hlt">waves</span> propagation in the nonlinear medium. PMID:26073066</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA621529','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA621529"><span>Calibration and Validation of Inertial Measurement Unit for <span class="hlt">Wave</span> Resolving Drifters</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2013-12-01</p> <p><span class="hlt">wave</span> field just described experiences accelerations due to both the <span class="hlt">wave</span> induced pressure <span class="hlt">variations</span> and the force of gravity. The gravitational ...with the vertical component also containing the gravitational acceleration constant (i.e., 9.81m/s2). B. SURFACE <span class="hlt">WAVE</span> ORBITAL MOTION SIMULATOR...18 C. ACCELERATION TO DISPLACEMENT .................................................19 IV</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20000021168','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20000021168"><span>Particle Acceleration by Cme-driven Shock <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Reames, Donald V.</p> <p>1999-01-01</p> <p>In the largest solar energetic particle (SEP) events, acceleration occurs at shock <span class="hlt">waves</span> driven out from the Sun by coronal mass ejections (CMEs). Peak particle intensities are a strong function of CME speed, although the intensities, spectra, and angular distributions of particles escaping the shock are highly modified by scattering on Alfven <span class="hlt">waves</span> produced by the streaming particles themselves. Element abundances vary in complex ways because ions with different values of Q/A resonate with different parts of the <span class="hlt">wave</span> spectrum, which varies with space and time. Just recently, we have begun to model these systematic <span class="hlt">variations</span> theoretically and to explore other consequences of proton-generated <span class="hlt">waves</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19206843','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19206843"><span>Mesoscale <span class="hlt">variations</span> in acoustic signals induced by atmospheric gravity <span class="hlt">waves</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chunchuzov, Igor; Kulichkov, Sergey; Perepelkin, Vitaly; Ziemann, Astrid; Arnold, Klaus; Kniffka, Anke</p> <p>2009-02-01</p> <p>The results of acoustic tomographic monitoring of the coherent structures in the lower atmosphere and the effects of these structures on acoustic signal parameters are analyzed in the present study. From the measurements of acoustic travel time fluctuations (periods 1 min-1 h) with distant receivers, the temporal fluctuations of the effective sound speed and wind speed are retrieved along different ray paths connecting an acoustic pulse source and several receivers. By using a coherence analysis of the fluctuations near spatially distanced ray turning points, the internal <span class="hlt">wave</span>-associated fluctuations are filtered and their spatial characteristics (coherences, horizontal phase velocities, and spatial scales) are estimated. The capability of acoustic tomography in estimating wind shear near ground is shown. A possible mechanism describing the temporal modulation of the near-ground wind field by ducted internal <span class="hlt">waves</span> in the troposphere is proposed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/875744','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/875744"><span>Finite Difference Modeling of <span class="hlt">Wave</span> Progpagation in Acoustic TiltedTI Media</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Zhang, Linbin; Rector III, James W.; Hoversten, G. Michael</p> <p>2005-03-21</p> <p>Based on an acoustic assumption (shear <span class="hlt">wave</span> velocity is zero) and a dispersion relation, we derive an acoustic <span class="hlt">wave</span> equation for P-<span class="hlt">waves</span> in tilted transversely isotropic (TTI) media (transversely isotropic media with a tilted symmetry axis). This equation has fewer parameters than an elastic <span class="hlt">wave</span> equation in TTI media and yields an <span class="hlt">accurate</span> description of P-<span class="hlt">wave</span> traveltimes and spreading-related attenuation. Our TTI acoustic <span class="hlt">wave</span> equation is a fourth-order equation in time and space. We demonstrate that the acoustic approximation allows the presence of shear <span class="hlt">waves</span> in the solution. The substantial differences in traveltime and amplitude between data created using VTImore » and TTI assumptions is illustrated in examples.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990027950&hterms=Lamb&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DLamb','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990027950&hterms=Lamb&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DLamb"><span>Lamb <span class="hlt">Wave</span> Assessment of Fiber Volume Fraction in Composites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Seale, Michael D.; Smith, Barry T.; Prosser, W. H.; Zalameda, Joseph N.</p> <p>1998-01-01</p> <p>Among the various techniques available, ultrasonic Lamb <span class="hlt">waves</span> offer a convenient method of examining composite materials. Since the Lamb <span class="hlt">wave</span> velocity depends on the elastic properties of a material, an effective tool exists to evaluate composites by measuring the velocity of these <span class="hlt">waves</span>. Lamb <span class="hlt">waves</span> can propagate over long distances and are sensitive to the desired in-plane elastic properties of the material. This paper discusses a study in which Lamb <span class="hlt">waves</span> were used to examine fiber volume fraction <span class="hlt">variations</span> of approximately 0.40-0.70 in composites. The Lamb <span class="hlt">wave</span> measurements were compared to fiber volume fractions obtained from acid digestion tests. Additionally, a model to predict the fiber volume fraction from Lamb <span class="hlt">wave</span> velocity values was evaluated.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.S23A1733L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.S23A1733L"><span>Seasonal <span class="hlt">variation</span> of seismic ambient noise level at King Sejong Station, Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, W.; Sheen, D.; Seo, K.; Yun, S.</p> <p>2009-12-01</p> <p>The generation of the secondary- or double-frequency (DF) microseisms with dominant frequencies between 0.1 and 0.5 Hz has been explained by nonlinear second-order pressure perturbations on the ocean bottom due to the interference of two ocean <span class="hlt">waves</span> of equal wavelengths traveling in opposite directions. Korea Polar Research Institute (KOPRI) has been operating a broadband seismic station (KSJ1) at King George Island (KGI), Antarctica, since 2001. Examining the ambient seismic noise level for the period from 2006 to 2008 at KSJ1, we found a significant seasonal <span class="hlt">variation</span> in the frequency range 0.1-0.5 Hz. Correlation of the DF peaks with significant ocean <span class="hlt">wave</span> height and peak <span class="hlt">wave</span> period models indicates that the oceanic infragravity <span class="hlt">waves</span> in the Drake Passage is a possible source to excite the DF microseisms at KGI. Location of King Sejong Station, Antarctica Seasonal <span class="hlt">variations</span> of DF peak, significant <span class="hlt">wave</span> height, and peak <span class="hlt">wave</span> period</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018IJBm...62..783H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018IJBm...62..783H"><span>Risk perception of heat <span class="hlt">waves</span> and its spatial <span class="hlt">variation</span> in Nanjing, China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huang, Lei; Yang, Qianqi; Li, Jie; Chen, Jin; He, Ruoying; Zhang, Can; Chen, Kai; Dong, Steven Guanpeng; Liu, Yang</p> <p>2018-05-01</p> <p>The intensity, frequency, and duration of heat <span class="hlt">waves</span> are expected to increase with climate change. In this study, we found a significant difference of public perceived effects of heat <span class="hlt">waves</span> and trust in government among urban, suburban, and rural districts. Rural residents had a significant higher effect perception than urbanites and also showed stronger willingness to have medical insurance or regular physical examinations. Meanwhile, suburban residents had the lowest trust perception in government among these three districts, which may be due to suburban districts' unique social structure and complex social issues. Besides, we assessed the relationship between the factor effect and demographic variables. The results showed that urban respondents' effect perception was significantly related to heat <span class="hlt">wave</span> experiences. Suburban respondents' effect perception was significantly related to age, income, and heat <span class="hlt">wave</span> experiences. And rural respondents' effect perception was significantly related to income and chronic diseases. Based on our results, much more attention needs to be paid to rural districts. The government should strengthen infrastructure construction such as cooling centers, improve emergency response plans and mechanisms, and increase reserves of emergency supplies in rural districts. Also, targeted risk communication is of the equal importance to aid the policy-makers improving the relationship with the public and regaining the public's trust and support.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29335771','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29335771"><span>Risk perception of heat <span class="hlt">waves</span> and its spatial <span class="hlt">variation</span> in Nanjing, China.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Huang, Lei; Yang, Qianqi; Li, Jie; Chen, Jin; He, Ruoying; Zhang, Can; Chen, Kai; Dong, Steven Guanpeng; Liu, Yang</p> <p>2018-05-01</p> <p>The intensity, frequency, and duration of heat <span class="hlt">waves</span> are expected to increase with climate change. In this study, we found a significant difference of public perceived effects of heat <span class="hlt">waves</span> and trust in government among urban, suburban, and rural districts. Rural residents had a significant higher effect perception than urbanites and also showed stronger willingness to have medical insurance or regular physical examinations. Meanwhile, suburban residents had the lowest trust perception in government among these three districts, which may be due to suburban districts' unique social structure and complex social issues. Besides, we assessed the relationship between the factor effect and demographic variables. The results showed that urban respondents' effect perception was significantly related to heat <span class="hlt">wave</span> experiences. Suburban respondents' effect perception was significantly related to age, income, and heat <span class="hlt">wave</span> experiences. And rural respondents' effect perception was significantly related to income and chronic diseases. Based on our results, much more attention needs to be paid to rural districts. The government should strengthen infrastructure construction such as cooling centers, improve emergency response plans and mechanisms, and increase reserves of emergency supplies in rural districts. Also, targeted risk communication is of the equal importance to aid the policy-makers improving the relationship with the public and regaining the public's trust and support.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017IJBm..tmp..333H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017IJBm..tmp..333H"><span>Risk perception of heat <span class="hlt">waves</span> and its spatial <span class="hlt">variation</span> in Nanjing, China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huang, Lei; Yang, Qianqi; Li, Jie; Chen, Jin; He, Ruoying; Zhang, Can; Chen, Kai; Dong, Steven Guanpeng; Liu, Yang</p> <p>2017-12-01</p> <p>The intensity, frequency, and duration of heat <span class="hlt">waves</span> are expected to increase with climate change. In this study, we found a significant difference of public perceived effects of heat <span class="hlt">waves</span> and trust in government among urban, suburban, and rural districts. Rural residents had a significant higher effect perception than urbanites and also showed stronger willingness to have medical insurance or regular physical examinations. Meanwhile, suburban residents had the lowest trust perception in government among these three districts, which may be due to suburban districts' unique social structure and complex social issues. Besides, we assessed the relationship between the factor effect and demographic variables. The results showed that urban respondents' effect perception was significantly related to heat <span class="hlt">wave</span> experiences. Suburban respondents' effect perception was significantly related to age, income, and heat <span class="hlt">wave</span> experiences. And rural respondents' effect perception was significantly related to income and chronic diseases. Based on our results, much more attention needs to be paid to rural districts. The government should strengthen infrastructure construction such as cooling centers, improve emergency response plans and mechanisms, and increase reserves of emergency supplies in rural districts. Also, targeted risk communication is of the equal importance to aid the policy-makers improving the relationship with the public and regaining the public's trust and support.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MPLB...3150350Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MPLB...3150350Y"><span>Characteristics of solitary <span class="hlt">waves</span>, quasiperiodic solutions, homoclinic breather solutions and rogue <span class="hlt">waves</span> in the generalized variable-coefficient forced Kadomtsev-Petviashvili equation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yan, Xue-Wei; Tian, Shou-Fu; Dong, Min-Jie; Zou, Li</p> <p>2017-12-01</p> <p>In this paper, the generalized variable-coefficient forced Kadomtsev-Petviashvili (gvcfKP) equation is investigated, which can be used to characterize the water <span class="hlt">waves</span> of long wavelength relating to nonlinear restoring forces. Using a dependent variable transformation and combining the Bell’s polynomials, we <span class="hlt">accurately</span> derive the bilinear expression for the gvcfKP equation. By virtue of bilinear expression, its solitary <span class="hlt">waves</span> are computed in a very direct method. By using the Riemann theta function, we derive the quasiperiodic solutions for the equation under some limitation factors. Besides, an effective way can be used to calculate its homoclinic breather <span class="hlt">waves</span> and rogue <span class="hlt">waves</span>, respectively, by using an extended homoclinic test function. We hope that our results can help enrich the dynamical behavior of the nonlinear <span class="hlt">wave</span> equations with variable-coefficient.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1212475-applying-cold-plasma-dispersion-relation-whistler-mode-chorus-waves-emfisis-wave-measurements-from-van-allen-probes','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1212475-applying-cold-plasma-dispersion-relation-whistler-mode-chorus-waves-emfisis-wave-measurements-from-van-allen-probes"><span>Applying the cold plasma dispersion relation to whistler mode chorus <span class="hlt">waves</span>: EMFISIS <span class="hlt">wave</span> measurements from the Van Allen Probes</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Hartley, D. P.; Chen, Y.; Kletzing, C. A.; ...</p> <p>2015-01-26</p> <p>Most theoretical <span class="hlt">wave</span> models require the power in the <span class="hlt">wave</span> magnetic field in order to determine the effect of chorus <span class="hlt">waves</span> on radiation belt electrons. However, researchers typically use the cold plasma dispersion relation to approximate the magnetic <span class="hlt">wave</span> power when only electric field data are available. In this study, the validity of using the cold plasma dispersion relation in this context is tested using Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) observations of both the electric and magnetic spectral intensities in the chorus <span class="hlt">wave</span> band (0.1–0.9 f ce). Results from this study indicate that the calculatedmore » <span class="hlt">wave</span> intensity is least <span class="hlt">accurate</span> during periods of enhanced <span class="hlt">wave</span> activity. For observed <span class="hlt">wave</span> intensities >10⁻³ nT², using the cold plasma dispersion relation results in an underestimate of the <span class="hlt">wave</span> intensity by a factor of 2 or greater 56% of the time over the full chorus <span class="hlt">wave</span> band, 60% of the time for lower band chorus, and 59% of the time for upper band chorus. Hence, during active periods, empirical chorus <span class="hlt">wave</span> models that are reliant on the cold plasma dispersion relation will underestimate chorus <span class="hlt">wave</span> intensities to a significant degree, thus causing questionable calculation of <span class="hlt">wave</span>-particle resonance effects on MeV electrons.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17712381','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17712381"><span>Millimeter- and submillimeter-<span class="hlt">wave</span> characterization of various fabrics.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dunayevskiy, Ilya; Bortnik, Bartosz; Geary, Kevin; Lombardo, Russell; Jack, Michael; Fetterman, Harold</p> <p>2007-08-20</p> <p>Transmission measurements of 14 fabrics are presented in the millimeter-<span class="hlt">wave</span> and submillimeter-<span class="hlt">wave</span> electromagnetic regions from 130 GHz to 1.2 THz. Three independent sources and experimental set-ups were used to obtain <span class="hlt">accurate</span> results over a wide spectral range. Reflectivity, a useful parameter for imaging applications, was also measured for a subset of samples in the submillimeter-<span class="hlt">wave</span> regime along with polarization sensitivity of the transmitted beam and transmission through doubled layers. All of the measurements were performed in free space. Details of these experimental set-ups along with their respective challenges are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70037400','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70037400"><span>Rayleigh-<span class="hlt">wave</span> mode separation by high-resolution linear radon transform</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Luo, Y.; Xia, J.; Miller, R.D.; Xu, Y.; Liu, J.; Liu, Q.</p> <p>2009-01-01</p> <p>Multichannel analysis of surface <span class="hlt">waves</span> (MASW) method is an effective tool for obtaining vertical shear <span class="hlt">wave</span> profiles from a single non-invasive measurement. One key step of the MASW method is generation of a dispersion image and extraction of a reliable dispersion curve from raw multichannel shot records. Because different Rayleigh-<span class="hlt">wave</span> modes normally interfere with each other in the time and space domain, it is necessary to perform mode separation and reconstruction to increase the accuracy of phase velocities determined from a dispersion image. In this paper, we demonstrate the effectiveness of high-resolution linear Radon transform (LRT) as a means of separating and reconstructing multimode, dispersive Rayleigh-<span class="hlt">wave</span> energy. We first introduce high-resolution LRT methods and Rayleigh-<span class="hlt">wave</span> mode separation using high-resolution LRT. Next, we use synthetic data and a real-world example to demonstrate the effectiveness of Rayleigh-<span class="hlt">wave</span> mode separation using high-resolution LRT. Our synthetic and real-world results demonstrate that (1) high-resolution LRT successfully separates and reconstructs multimode dispersive Rayleigh-<span class="hlt">wave</span> energy with high resolution allowing the multimode energy to be more <span class="hlt">accurately</span> determined. The horizontal resolution of the Rayleigh-<span class="hlt">wave</span> method can be increased by extraction of dispersion curves from a pair of traces in the mode-separated shot gather and (2) multimode separation and reconstruction expand the usable frequency range of higher mode dispersive energy, which increases the depth of investigation and provides a means for <span class="hlt">accurately</span> determining cut-off frequencies. ?? 2009 The Authors Journal compilation ?? 2009 RAS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.waveworkshop.org/10thWaves/ProgramFrameset.htm','USGSPUBS'); return false;" href="http://www.waveworkshop.org/10thWaves/ProgramFrameset.htm"><span>Coupling alongshore <span class="hlt">variations</span> in <span class="hlt">wave</span> energy to beach morphologic change using the SWAN <span class="hlt">wave</span> model at Ocean Beach, San Francisco, CA</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Eshleman, Jodi L.; Barnard, Patrick L.; Erikson, Li H.; Hanes, Daniel M.</p> <p>2007-01-01</p> <p>Coastal managers have faced increasing pressure to manage their resources wisely over the last century as a result of heightened development and changing environmental forcing. It is crucial to understand seasonal changes in beach volume and shape in order to identify areas vulnerable to accelerated erosion. Shepard (1950) was among the first to quantify seasonal beach cycles. Sonu and Van Beek (1971) and Wright et al. (1985) described commonly occurring beach states. Most studies utilize widest spaced 2-D cross shore profiles or shorelines extracted from aerial photographs (e.g. Winant et al. 1975; Aubrey, 1979, Aubrey and Ross, 1985; Larson and Kraus, 1994; Jimenez et al., 1977; Lacey and Peck, 1998; Guillen et al., 1999; Norcorss et al., 2002) to analyzed systematic changes in beach evolution. But with the exception of established field stations, such as Duck, NC (Birkemeier and Mason, 1984), ans Hazaki Oceanographical Research Station (HORS) in Japan (Katoh, 1997), there are very few beach change data sets with high temporal and spatial resolutions (e.g. Dail et al., 2000; Ruggiero et al., 2005; Yates et al., in press). Comprehensive sets of nearshore morphological data and local in situ measurements outside of these field stations are very rare and virtually non-existent high-energy coasts. Studied that have attempted to relate <span class="hlt">wave</span> statistics to beach morphology change require some knowledge of the nearshore <span class="hlt">wave</span> climate, and have had limited success using offshore measurement (Sonu and Van Beek, 1971; Dail et al., 2000). The primary objective of this study is to qualitatively compare spatially variable nearshore <span class="hlt">wave</span> predictions to beach change measurements in order to understand the processes responsible for a persistent erosion 'hotspot' at Ocean Beach, San Francisco, CA. Local <span class="hlt">wave</span> measurements are used to calibrate and validate a <span class="hlt">wave</span> model that provides nearshore <span class="hlt">wave</span> prediction along the beach. The model is run for thousands of binned offshore <span class="hlt">wave</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012REDS..167..841R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012REDS..167..841R"><span><span class="hlt">Accurate</span> monoenergetic electron parameters of laser wakefield in a bubble model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Raheli, A.; Rahmatallahpur, S. H.</p> <p>2012-11-01</p> <p>A reliable analytical expression for the potential of plasma <span class="hlt">waves</span> with phase velocities near the speed of light is derived. The presented spheroid cavity model is more consistent than the previous spherical and ellipsoidal model and it explains the mono-energetic electron trajectory more <span class="hlt">accurately</span>, especially at the relativistic region. As a result, the quasi-mono-energetic electrons output beam interacting with the laser plasma can be more appropriately described with this model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.9834V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.9834V"><span>A scalable method for computing quadruplet <span class="hlt">wave-wave</span> interactions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Van Vledder, Gerbrant</p> <p>2017-04-01</p> <p>Non-linear four-<span class="hlt">wave</span> interactions are a key physical process in the evolution of wind generated ocean <span class="hlt">waves</span>. The present generation operational <span class="hlt">wave</span> models use the Discrete Interaction Approximation (DIA), but it accuracy is poor. It is now generally acknowledged that the DIA should be replaced with a more <span class="hlt">accurate</span> method to improve predicted spectral shapes and derived parameters. The search for such a method is challenging as one should find a balance between accuracy and computational requirements. Such a method is presented here in the form of a scalable and adaptive method that can mimic both the time consuming exact Snl4 approach and the fast but inaccurate DIA, and everything in between. The method provides an elegant approach to improve the DIA, not by including more arbitrarily shaped <span class="hlt">wave</span> number configurations, but by a mathematically consistent reduction of an exact method, viz. the WRT method. The adaptiveness is to adapt the abscissa of the locus integrand in relation to the magnitude of the known terms. The adaptiveness is extended to the highest level of the WRT method to select interacting wavenumber configurations in a hierarchical way in relation to their importance. This adaptiveness results in a speed-up of one to three orders of magnitude depending on the measure of accuracy. This definition of accuracy should not be expressed in terms of the quality of the transfer integral for academic spectra but rather in terms of <span class="hlt">wave</span> model performance in a dynamic run. This has consequences for the balance between the required accuracy and the computational workload for evaluating these interactions. The performance of the scalable method on different scales is illustrated with results from academic spectra, simple growth curves to more complicated field cases using a 3G-<span class="hlt">wave</span> model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/867845','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/867845"><span>Method and apparatus for millimeter-<span class="hlt">wave</span> detection of thermal <span class="hlt">waves</span> for materials evaluation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Gopalsami, Nachappa; Raptis, Apostolos C.</p> <p>1991-01-01</p> <p>A method and apparatus for generating thermal <span class="hlt">waves</span> in a sample and for measuring thermal inhomogeneities at subsurface levels using millimeter-<span class="hlt">wave</span> radiometry. An intensity modulated heating source is oriented toward a narrow spot on the surface of a material sample and thermal radiation in a narrow volume of material around the spot is monitored using a millimeter-<span class="hlt">wave</span> radiometer; the radiometer scans the sample point-by-point and a computer stores and displays in-phase and quadrature phase components of thermal radiations for each point on the scan. Alternatively, an intensity modulated heating source is oriented toward a relatively large surface area in a material sample and <span class="hlt">variations</span> in thermal radiation within the full field of an antenna array are obtained using an aperture synthesis radiometer technique.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ApGeo..14..247Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApGeo..14..247Z"><span>Research and application of spectral inversion technique in frequency domain to improve resolution of converted PS-<span class="hlt">wave</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Hua; He, Zhen-Hua; Li, Ya-Lin; Li, Rui; He, Guamg-Ming; Li, Zhong</p> <p>2017-06-01</p> <p>Multi-<span class="hlt">wave</span> exploration is an effective means for improving precision in the exploration and development of complex oil and gas reservoirs that are dense and have low permeability. However, converted <span class="hlt">wave</span> data is characterized by a low signal-to-noise ratio and low resolution, because the conventional deconvolution technology is easily affected by the frequency range limits, and there is limited scope for improving its resolution. The spectral inversion techniques is used to identify λ/8 thin layers and its breakthrough regarding band range limits has greatly improved the seismic resolution. The difficulty associated with this technology is how to use the stable inversion algorithm to obtain a high-precision reflection coefficient, and then to use this reflection coefficient to reconstruct broadband data for processing. In this paper, we focus on how to improve the vertical resolution of the converted PS-<span class="hlt">wave</span> for multi-<span class="hlt">wave</span> data processing. Based on previous research, we propose a least squares inversion algorithm with a total <span class="hlt">variation</span> constraint, in which we uses the total variance as a priori information to solve under-determined problems, thereby improving the accuracy and stability of the inversion. Here, we simulate the Gaussian fitting amplitude spectrum to obtain broadband wavelet data, which we then process to obtain a higher resolution converted <span class="hlt">wave</span>. We successfully apply the proposed inversion technology in the processing of high-resolution data from the Penglai region to obtain higher resolution converted <span class="hlt">wave</span> data, which we then verify in a theoretical test. Improving the resolution of converted PS-<span class="hlt">wave</span> data will provide more <span class="hlt">accurate</span> data for subsequent velocity inversion and the extraction of reservoir reflection information.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.4821N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.4821N"><span><span class="hlt">Wave</span>-current interactions at the Flo<span class="hlt">Wave</span> Ocean Energy Research Facility</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Noble, Donald; Davey, Thomas; Steynor, Jeffrey; Bruce, Tom; Smith, Helen; Kaklis, Panagiotis</p> <p>2015-04-01</p> <p> initial tests used a correction factor based on a linear combination of <span class="hlt">wave</span> and current (Smith 1997), which was found to be reasonably <span class="hlt">accurate</span>, although the requirement for higher order theory is also explored. Flo<span class="hlt">Wave</span> is a new facility that offers the ability to study <span class="hlt">wave</span>-current interactions at arbitrary angles with relatively fast currents. This is important as <span class="hlt">waves</span> and tidal currents at sites of interest for renewable energy generation may not be aligned (Lewis et al. 2014), and so better understanding of these conditions is required. References Lewis, M.J. et al., 2014. Realistic <span class="hlt">wave</span> conditions and their influence on quantifying the tidal stream energy resource. Applied Energy, 136, pp.495-508. Smith, J.M., 1997. Coastal Engineering Technical Note One-dimensional <span class="hlt">wave</span>-current interaction (CETN IV-9), Vicksburg, MS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MNRAS.tmp..873B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MNRAS.tmp..873B"><span>Accuracy of inference on the physics of binary evolution from gravitational-<span class="hlt">wave</span> observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barrett, Jim W.; Gaebel, Sebastian M.; Neijssel, Coenraad J.; Vigna-Gómez, Alejandro; Stevenson, Simon; Berry, Christopher P. L.; Farr, Will M.; Mandel, Ilya</p> <p>2018-04-01</p> <p>The properties of the population of merging binary black holes encode some of the uncertain physics underlying the evolution of massive stars in binaries. The binary black hole merger rate and chirp-mass distribution are being measured by ground-based gravitational-<span class="hlt">wave</span> detectors. We consider isolated binary evolution, and explore how <span class="hlt">accurately</span> the physical model can be constrained with such observations by applying the Fisher information matrix to the merging black hole population simulated with the rapid binary-population synthesis code COMPAS. We investigate <span class="hlt">variations</span> in four COMPAS parameters: common-envelope efficiency, kick-velocity dispersion, and mass-loss rates during the luminous blue variable and Wolf-Rayet stellar-evolutionary phases. We find that ˜1000 observations would constrain these model parameters to a fractional accuracy of a few per cent. Given the empirically determined binary black hole merger rate, we can expect gravitational-<span class="hlt">wave</span> observations alone to place strong constraints on the physics of stellar and binary evolution within a few years. Our approach can be extended to use other observational data sets; combining observations at different evolutionary stages will lead to a better understanding of stellar and binary physics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MNRAS.477.4685B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MNRAS.477.4685B"><span>Accuracy of inference on the physics of binary evolution from gravitational-<span class="hlt">wave</span> observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barrett, Jim W.; Gaebel, Sebastian M.; Neijssel, Coenraad J.; Vigna-Gómez, Alejandro; Stevenson, Simon; Berry, Christopher P. L.; Farr, Will M.; Mandel, Ilya</p> <p>2018-07-01</p> <p>The properties of the population of merging binary black holes encode some of the uncertain physics underlying the evolution of massive stars in binaries. The binary black hole merger rate and chirp-mass distribution are being measured by ground-based gravitational-<span class="hlt">wave</span> detectors. We consider isolated binary evolution, and explore how <span class="hlt">accurately</span> the physical model can be constrained with such observations by applying the Fisher information matrix to the merging black hole population simulated with the rapid binary-population synthesis code COMPAS. We investigate <span class="hlt">variations</span> in four COMPAS parameters: common-envelope efficiency, kick-velocity dispersion and mass-loss rates during the luminous blue variable, and Wolf-Rayet stellar-evolutionary phases. We find that ˜1000 observations would constrain these model parameters to a fractional accuracy of a few per cent. Given the empirically determined binary black hole merger rate, we can expect gravitational-<span class="hlt">wave</span> observations alone to place strong constraints on the physics of stellar and binary evolution within a few years. Our approach can be extended to use other observational data sets; combining observations at different evolutionary stages will lead to a better understanding of stellar and binary physics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PTEP.2018d1D01Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PTEP.2018d1D01Z"><span>New trial <span class="hlt">wave</span> function for the nuclear cluster structure of nuclei</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhou, Bo</p> <p>2018-04-01</p> <p>A new trial <span class="hlt">wave</span> function is proposed for nuclear cluster physics, in which an exact solution to the long-standing center-of-mass problem is given. In the new approach, the widths of the single-nucleon Gaussian <span class="hlt">wave</span> packets and the widths of the relative Gaussian <span class="hlt">wave</span> functions describing correlations of nucleons or clusters are treated as variables in the explicit intrinsic <span class="hlt">wave</span> function of the nuclear system. As an example, this new <span class="hlt">wave</span> function was applied to study the typical {^{20}Ne} (α+{{^{16}}O}) cluster system. By removing exactly the spurious center-of-mass effect in a very simple way, the energy curve of {^{20}Ne} was obtained by <span class="hlt">variational</span> calculations with the width of the α cluster, the width of the {{^{16}}O} cluster, and the size parameter of the nucleus. These are considered the three crucial <span class="hlt">variational</span> variables in describing the {^{20}Ne} (α+{{^{16}}O}) cluster system. This shows that the new <span class="hlt">wave</span> function can be a very interesting new tool for studying many-body and cluster effects in nuclear physics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22596815-estimation-viscoelastic-parameters-prony-series-from-shear-wave-propagation','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22596815-estimation-viscoelastic-parameters-prony-series-from-shear-wave-propagation"><span>Estimation of viscoelastic parameters in Prony series from shear <span class="hlt">wave</span> propagation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Jung, Jae-Wook; Hong, Jung-Wuk, E-mail: j.hong@kaist.ac.kr, E-mail: jwhong@alum.mit.edu; Lee, Hyoung-Ki</p> <p>2016-06-21</p> <p>When acquiring <span class="hlt">accurate</span> ultrasonic images, we must precisely estimate the mechanical properties of the soft tissue. This study investigates and estimates the viscoelastic properties of the tissue by analyzing shear <span class="hlt">waves</span> generated through an acoustic radiation force. The shear <span class="hlt">waves</span> are sourced from a localized pushing force acting for a certain duration, and the generated <span class="hlt">waves</span> travel horizontally. The <span class="hlt">wave</span> velocities depend on the mechanical properties of the tissue such as the shear modulus and viscoelastic properties; therefore, we can inversely calculate the properties of the tissue through parametric studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005PhTea..43..344P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005PhTea..43..344P"><span>Kinesthetic Transverse <span class="hlt">Wave</span> Demonstration</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pantidos, Panagiotis; Patapis, Stamatis</p> <p>2005-09-01</p> <p>This is a <span class="hlt">variation</span> on the String and Sticky Tape demonstration "The <span class="hlt">Wave</span> Game," suggested by Ron Edge. A group of students stand side by side, each one holding a card chest high with both hands. The teacher cues the first student to begin raising and lowering his card. When he starts lowering his card, the next student begins to raise his. As succeeding students move their cards up and down, a <span class="hlt">wave</span> such as that shown in the figure is produced. To facilitate the process, students' motions were synchronized with the ticks of a metronome (without such synchronization it was nearly impossible to generate a satisfactory <span class="hlt">wave</span>). Our <span class="hlt">waves</span> typically had a frequency of about 1 Hz and a wavelength of around 3 m. We videotaped the activity so that the students could analyze the motions. The (17-year-old) students had not received any prior instruction regarding <span class="hlt">wave</span> motion and did not know beforehand the nature of the exercise they were about to carry out. During the activity they were asked what a transverse <span class="hlt">wave</span> is. Most of them quickly realized, without teacher input, that while the <span class="hlt">wave</span> propagated horizontally, the only motion of the transmitting medium (them) was vertical. They located the equilibrium points of the oscillations, the crests and troughs of the <span class="hlt">waves</span>, and identified the wavelength. The teacher defined for them the period of the oscillations of the motion of a card to be the total time for one cycle. The students measured this time and then several asserted that it was the same as the <span class="hlt">wave</span> period. Knowing the length of the <span class="hlt">waves</span> and the number of <span class="hlt">waves</span> per second, the next step can easily be to find the <span class="hlt">wave</span> speed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29364117','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29364117"><span>Improved Visualization of Gastrointestinal Slow <span class="hlt">Wave</span> Propagation Using a Novel Wavefront-Orientation Interpolation Technique.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mayne, Terence P; Paskaranandavadivel, Niranchan; Erickson, Jonathan C; OGrady, Gregory; Cheng, Leo K; Angeli, Timothy R</p> <p>2018-02-01</p> <p>High-resolution mapping of gastrointestinal (GI) slow <span class="hlt">waves</span> is a valuable technique for research and clinical applications. Interpretation of high-resolution GI mapping data relies on animations of slow <span class="hlt">wave</span> propagation, but current methods remain as rudimentary, pixelated electrode activation animations. This study aimed to develop improved methods of visualizing high-resolution slow <span class="hlt">wave</span> recordings that increases ease of interpretation. The novel method of "wavefront-orientation" interpolation was created to account for the planar movement of the slow <span class="hlt">wave</span> wavefront, negate any need for distance calculations, remain robust in atypical wavefronts (i.e., dysrhythmias), and produce an appropriate interpolation boundary. The wavefront-orientation method determines the orthogonal wavefront direction and calculates interpolated values as the mean slow <span class="hlt">wave</span> activation-time (AT) of the pair of linearly adjacent electrodes along that direction. Stairstep upsampling increased smoothness and clarity. Animation accuracy of 17 human high-resolution slow <span class="hlt">wave</span> recordings (64-256 electrodes) was verified by visual comparison to the prior method showing a clear improvement in <span class="hlt">wave</span> smoothness that enabled more <span class="hlt">accurate</span> interpretation of propagation, as confirmed by an assessment of clinical applicability performed by eight GI clinicians. Quantitatively, the new method produced <span class="hlt">accurate</span> interpolation values compared to experimental data (mean difference 0.02 ± 0.05 s) and was <span class="hlt">accurate</span> when applied solely to dysrhythmic data (0.02 ± 0.06 s), both within the error in manual AT marking (mean 0.2 s). Mean interpolation processing time was 6.0 s per <span class="hlt">wave</span>. These novel methods provide a validated visualization platform that will improve analysis of high-resolution GI mapping in research and clinical translation.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25484609','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25484609"><span><span class="hlt">Wave</span> energy devices with compressible volumes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kurniawan, Adi; Greaves, Deborah; Chaplin, John</p> <p>2014-12-08</p> <p>We present an analysis of <span class="hlt">wave</span> energy devices with air-filled compressible submerged volumes, where variability of volume is achieved by means of a horizontal surface free to move up and down relative to the body. An analysis of bodies without power take-off (PTO) systems is first presented to demonstrate the positive effects a compressible volume could have on the body response. Subsequently, two compressible device <span class="hlt">variations</span> are analysed. In the first <span class="hlt">variation</span>, the compressible volume is connected to a fixed volume via an air turbine for PTO. In the second <span class="hlt">variation</span>, a water column separates the compressible volume from another volume, which is fitted with an air turbine open to the atmosphere. Both floating and bottom-fixed, axisymmetric, configurations are considered, and linear analysis is employed throughout. Advantages and disadvantages of each device are examined in detail. Some configurations with displaced volumes less than 2000 m 3 and with constant turbine coefficients are shown to be capable of achieving 80% of the theoretical maximum absorbed power over a <span class="hlt">wave</span> period range of about 4 s.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4241014','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4241014"><span><span class="hlt">Wave</span> energy devices with compressible volumes</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kurniawan, Adi; Greaves, Deborah; Chaplin, John</p> <p>2014-01-01</p> <p>We present an analysis of <span class="hlt">wave</span> energy devices with air-filled compressible submerged volumes, where variability of volume is achieved by means of a horizontal surface free to move up and down relative to the body. An analysis of bodies without power take-off (PTO) systems is first presented to demonstrate the positive effects a compressible volume could have on the body response. Subsequently, two compressible device <span class="hlt">variations</span> are analysed. In the first <span class="hlt">variation</span>, the compressible volume is connected to a fixed volume via an air turbine for PTO. In the second <span class="hlt">variation</span>, a water column separates the compressible volume from another volume, which is fitted with an air turbine open to the atmosphere. Both floating and bottom-fixed, axisymmetric, configurations are considered, and linear analysis is employed throughout. Advantages and disadvantages of each device are examined in detail. Some configurations with displaced volumes less than 2000 m3 and with constant turbine coefficients are shown to be capable of achieving 80% of the theoretical maximum absorbed power over a <span class="hlt">wave</span> period range of about 4 s. PMID:25484609</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhRvD..97j4057M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhRvD..97j4057M"><span>Bayesian reconstruction of gravitational <span class="hlt">wave</span> bursts using chirplets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Millhouse, Margaret; Cornish, Neil J.; Littenberg, Tyson</p> <p>2018-05-01</p> <p>The LIGO-Virgo Collaboration uses a variety of techniques to detect and characterize gravitational <span class="hlt">waves</span>. One approach is to use templates—models for the signals derived from Einstein's equations. Another approach is to extract the signals directly from the coherent response of the detectors in the LIGO-Virgo network. Both approaches played an important role in the first gravitational <span class="hlt">wave</span> detections. Here we extend the Bayes<span class="hlt">Wave</span> analysis algorithm, which reconstructs gravitational <span class="hlt">wave</span> signals using a collection of continuous wavelets, to use a generalized wavelet family, known as chirplets, that have time-evolving frequency content. Since generic gravitational <span class="hlt">wave</span> signals have frequency content that evolves in time, a collection of chirplets provides a more compact representation of the signal, resulting in more <span class="hlt">accurate</span> waveform reconstructions, especially for low signal-to-noise events, and events that occupy a large time-frequency volume.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5415686','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5415686"><span><span class="hlt">Wave</span> directional spreading from point field measurements</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Venugopal, V.; Borthwick, A. G. L.</p> <p>2017-01-01</p> <p>Ocean <span class="hlt">waves</span> have multidirectional components. Most <span class="hlt">wave</span> measurements are taken at a single point, and so fail to capture information about the relative directions of the <span class="hlt">wave</span> components directly. Conventional means of directional estimation require a minimum of three concurrent time series of measurements at different spatial locations in order to derive information on local directional <span class="hlt">wave</span> spreading. Here, the relationship between <span class="hlt">wave</span> nonlinearity and directionality is utilized to estimate local spreading without the need for multiple concurrent measurements, following Adcock & Taylor (Adcock & Taylor 2009 Proc. R. Soc. A 465, 3361–3381. (doi:10.1098/rspa.2009.0031)), with the assumption that directional spreading is frequency independent. The method is applied to measurements recorded at the North Alwyn platform in the northern North Sea, and the results compared against estimates of <span class="hlt">wave</span> spreading by conventional measurement methods and hindcast data. Records containing freak <span class="hlt">waves</span> were excluded. It is found that the method provides <span class="hlt">accurate</span> estimates of <span class="hlt">wave</span> spreading over a range of conditions experienced at North Alwyn, despite the noisy chaotic signals that characterize such ocean <span class="hlt">wave</span> data. The results provide further confirmation that Adcock and Taylor's method is applicable to metocean data and has considerable future promise as a technique to recover estimates of <span class="hlt">wave</span> spreading from single point <span class="hlt">wave</span> measurement devices. PMID:28484326</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910048826&hterms=polarizability+Argon&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dpolarizability%2BArgon','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910048826&hterms=polarizability+Argon&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dpolarizability%2BArgon"><span>The determination of <span class="hlt">accurate</span> dipole polarizabilities alpha and gamma for the noble gases</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rice, Julia E.; Taylor, Peter R.; Lee, Timothy J.; Almlof, Jan</p> <p>1991-01-01</p> <p><span class="hlt">Accurate</span> static dipole polarizabilities alpha and gamma of the noble gases He through Xe were determined using <span class="hlt">wave</span> functions of similar quality for each system. Good agreement with experimental data for the static polarizability gamma was obtained for Ne and Xe, but not for Ar and Kr. Calculations suggest that the experimental values for these latter ions are too low.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1613508L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1613508L"><span>Space-time properties of wind-<span class="hlt">waves</span>: a new look at directional <span class="hlt">wave</span> distributions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Leckler, Fabien; Ardhuin, Fabrice; Benetazzo, Alvise; Fedele, Francesco; Bergamasco, Filippo; Dulov, Vladimir</p> <p>2014-05-01</p> <p>Few <span class="hlt">accurate</span> observed directional <span class="hlt">wave</span> spectra are available in the literature at spatial scales ranging between 0.5 and 5.0 m. These intermediate <span class="hlt">wave</span> scales, relevant for air-sea fluxes and remote sensing are also expected to feed back on the dominant <span class="hlt">wave</span> properties through <span class="hlt">wave</span> generation. These <span class="hlt">wave</span> scales can be prolifically investigated using the well-known optical stereo methods that provides, from a couple of synchronized images, instantaneous representation of <span class="hlt">wave</span> elevations over a given sea surface. Thus, two stereo systems (the so-called <span class="hlt">Wave</span> Acquisition Stereo Systems, WASS) were deployed on top of the deep-water platform at Katsiveli, in the Black Sea, in September 2011 and 2013. From image pairs taken by the couple of synchronized high-resolution cameras, ocean surfaces have been reconstructed by stereo-triangulation. Here we analyze sea states corresponding to mean wind speeds of 11 to 14 m/s, and young <span class="hlt">wave</span> ages of 0.35 to 0.42, associated to significant <span class="hlt">wave</span> heights of 0.3 to 0.55m. As a result, four 12 Hz time evolutions of sea surface elevation maps with areas about 10 x 10 m2 have been obtained for sequence durations ranging between 15 and 30 minutes, and carefully validated with nearby capacitance <span class="hlt">wave</span> gauges. The evolving free surfaces elevations were processed into frequency-wavenumber-direction 3D spectra. We found that <span class="hlt">wave</span> energy chiefly follows the dispersion relation up to frequency of 1.6Hz and wavenumber of 10 rad/m, corresponding to wavelength of about 0.5 m. These spectra also depict well the energy contribution from non-linear <span class="hlt">waves</span>, which is quantified and compared to theory. A strong bi-modality of the linear spectra was also observed, with the angle of the two maxima separated by about 160 degrees. Furthermore, spectra also exhibit the bimodality of the non-linear part. Integrated over positive frequencies to obtain wavenumber spectra unambiguous in direction, the bimodality of the spectra is partially hidden by the energy from</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018E3SWC..2900019H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018E3SWC..2900019H"><span>Comparison of recent S-<span class="hlt">wave</span> indicating methods</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hubicka, Katarzyna; Sokolowski, Jakub</p> <p>2018-01-01</p> <p>Seismic event consists of surface <span class="hlt">waves</span> and body <span class="hlt">waves</span>. Due to the fact that the body <span class="hlt">waves</span> are faster (P-<span class="hlt">waves</span>) and more energetic (S-<span class="hlt">waves</span>) in literature the problem of their analysis is taken more often. The most universal information that is received from the recorded <span class="hlt">wave</span> is its moment of arrival. When this information is obtained from at least four seismometers in different locations, the epicentre of the particular event can be estimated [1]. Since the recorded body <span class="hlt">waves</span> may overlap in signal, the problem of <span class="hlt">wave</span> onset moment is considered more often for faster P-<span class="hlt">wave</span> than S-<span class="hlt">wave</span>. This however does not mean that the issue of S-<span class="hlt">wave</span> arrival time is not taken at all. As the process of manual picking is time-consuming, methods of automatic detection are recommended (these however may be less <span class="hlt">accurate</span>). In this paper four recently developed methods estimating S-<span class="hlt">wave</span> arrival are compared: the method operating on empirical mode decomposition and Teager-Kaiser operator [2], the modification of STA/LTA algorithm [3], the method using a nearest neighbour-based approach [4] and the algorithm operating on characteristic of signals' second moments. The methods will be also compared to wellknown algorithm based on the autoregressive model [5]. The algorithms will be tested in terms of their S-<span class="hlt">wave</span> arrival identification accuracy on real data originating from International Research Institutions for Seismology (IRIS) database.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPhCS.774a2048K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPhCS.774a2048K"><span>Peculiarities of evolutions of elastic-plastic shock compression <span class="hlt">waves</span> in different materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kanel, G. I.; Savinykh, A. S.; Garkushin, G. V.; Razorenov, S. V.; Ashitkov, S. I.; Zaretsky, E. B.</p> <p>2016-11-01</p> <p>In the paper, we discuss such unexpected features in the <span class="hlt">wave</span> evolution in solids as strongly nonlinear uniaxial elastic compression in a picosecond time range, a departure from self-similar development of the <span class="hlt">wave</span> process which is accompanied with apparent sub-sonic <span class="hlt">wave</span> propagation, changes of shape of elastic precursor <span class="hlt">wave</span> as a result of <span class="hlt">variations</span> in the material structure and the temperature, unexpected peculiarities of reflection of elastic-plastic <span class="hlt">waves</span> from free surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14683056','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14683056"><span>Drift-<span class="hlt">wave</span> turbulence and zonal flow generation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Balescu, R</p> <p>2003-10-01</p> <p>Drift-<span class="hlt">wave</span> turbulence in a plasma is analyzed on the basis of the <span class="hlt">wave</span> Liouville equation, describing the evolution of the distribution function of <span class="hlt">wave</span> packets (quasiparticles) characterized by position x and <span class="hlt">wave</span> vector k. A closed kinetic equation is derived for the ensemble-averaged part of this function by the methods of nonequilibrium statistical mechanics. It has the form of a non-Markovian advection-diffusion equation describing coupled diffusion processes in x and k spaces. General forms of the diffusion coefficients are obtained in terms of Lagrangian velocity correlations. The latter are calculated in the decorrelation trajectory approximation, a method recently developed for an <span class="hlt">accurate</span> measure of the important trapping phenomena of particles in the rugged electrostatic potential. The analysis of individual decorrelation trajectories provides an illustration of the fragmentation of drift-<span class="hlt">wave</span> structures in the radial direction and the generation of long-wavelength structures in the poloidal direction that are identified as zonal flows.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4559855','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4559855"><span>Seeing and Being Seen: Predictors of <span class="hlt">Accurate</span> Perceptions about Classmates’ Relationships</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Neal, Jennifer Watling; Neal, Zachary P.; Cappella, Elise</p> <p>2015-01-01</p> <p>This study examines predictors of observer accuracy (i.e. seeing) and target accuracy (i.e. being seen) in perceptions of classmates’ relationships in a predominantly African American sample of 420 second through fourth graders (ages 7 – 11). Girls, children in higher grades, and children in smaller classrooms were more <span class="hlt">accurate</span> observers. Targets (i.e. pairs of children) were more <span class="hlt">accurately</span> observed when they occurred in smaller classrooms of higher grades and involved same-sex, high-popularity, and similar-popularity children. Moreover, relationships between pairs of girls were more <span class="hlt">accurately</span> observed than relationships between pairs of boys. As a set, these findings suggest the importance of both observer and target characteristics for children’s <span class="hlt">accurate</span> perceptions of classroom relationships. Moreover, the substantial <span class="hlt">variation</span> in observer accuracy and target accuracy has methodological implications for both peer-reported assessments of classroom relationships and the use of stochastic actor-based models to understand peer selection and socialization processes. PMID:26347582</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017OcMod.116..118R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017OcMod.116..118R"><span>Efficient non-hydrostatic modelling of 3D <span class="hlt">wave</span>-induced currents using a subgrid approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rijnsdorp, Dirk P.; Smit, Pieter B.; Zijlema, Marcel; Reniers, Ad J. H. M.</p> <p>2017-08-01</p> <p><span class="hlt">Wave</span>-induced currents are an ubiquitous feature in coastal waters that can spread material over the surf zone and the inner shelf. These currents are typically under resolved in non-hydrostatic <span class="hlt">wave</span>-flow models due to computational constraints. Specifically, the low vertical resolutions adequate to describe the <span class="hlt">wave</span> dynamics - and required to feasibly compute at the scales of a field site - are too coarse to account for the relevant details of the three-dimensional (3D) flow field. To describe the relevant dynamics of both <span class="hlt">wave</span> and currents, while retaining a model framework that can be applied at field scales, we propose a two grid approach to solve the governing equations. With this approach, the vertical accelerations and non-hydrostatic pressures are resolved on a relatively coarse vertical grid (which is sufficient to <span class="hlt">accurately</span> resolve the <span class="hlt">wave</span> dynamics), whereas the horizontal velocities and turbulent stresses are resolved on a much finer subgrid (of which the resolution is dictated by the vertical scale of the mean flows). This approach ensures that the discrete pressure Poisson equation - the solution of which dominates the computational effort - is evaluated on the coarse grid scale, thereby greatly improving efficiency, while providing a fine vertical resolution to resolve the vertical <span class="hlt">variation</span> of the mean flow. This work presents the general methodology, and discusses the numerical implementation in the SWASH <span class="hlt">wave</span>-flow model. Model predictions are compared with observations of three flume experiments to demonstrate that the subgrid approach captures both the nearshore evolution of the <span class="hlt">waves</span>, and the <span class="hlt">wave</span>-induced flows like the undertow profile and longshore current. The accuracy of the subgrid predictions is comparable to fully resolved 3D simulations - but at much reduced computational costs. The findings of this work thereby demonstrate that the subgrid approach has the potential to make 3D non-hydrostatic simulations feasible at the scale of a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MS%26E..252a2081C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MS%26E..252a2081C"><span>EVOLUTION of the Pressure <span class="hlt">Wave</span> Supercharger Concept</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Costiuc, Iuliana; Chiru, Anghel</p> <p>2017-10-01</p> <p>Born more than a century ago, the concept of exploiting the pressure <span class="hlt">wave</span> phenomenon has evolved with rather small steps, experiencing an accelerated progress over the past decades. This paper aims an overview on the researchers’ results over time regarding the pressure <span class="hlt">wave</span> technology and its applications, pointing out on the internal combustion engine’s supercharging application. This review complements the past reports on the subject, presenting the evolution of the concept and technology, as well as the researcher’s efforts on solving the specific shortcomings of this pressure <span class="hlt">wave</span> technology. Undoubtedly, the pressure <span class="hlt">wave</span> rotors have been a research goal over the years. At first, most of the researches were experimental and the theoretical calculations required to improve the technology were too arduous. Recently, new computer software dedicated to <span class="hlt">accurate</span> simulation of the processes governing the <span class="hlt">wave</span> rotor operation, altogether with modern experimental measurement instruments and well-developed diagnostic techniques have opened wide possibilities to innovate the pressure <span class="hlt">wave</span> supercharging technology. This paper also highlights the challenges that specialists still have to overcome and aspects to become future preoccupations and research directions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22591185-analysis-shear-wave-velocity-structure-obtained-from-surface-wave-methods-bornova-izmir','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22591185-analysis-shear-wave-velocity-structure-obtained-from-surface-wave-methods-bornova-izmir"><span>Analysis shear <span class="hlt">wave</span> velocity structure obtained from surface <span class="hlt">wave</span> methods in Bornova, Izmir</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Pamuk, Eren, E-mail: eren.pamuk@deu.edu.tr; Akgün, Mustafa, E-mail: mustafa.akgun@deu.edu.tr; Özdağ, Özkan Cevdet, E-mail: cevdet.ozdag@deu.edu.tr</p> <p>2016-04-18</p> <p>Properties of the soil from the bedrock is necessary to describe <span class="hlt">accurately</span> and reliably for the reduction of earthquake damage. Because seismic <span class="hlt">waves</span> change their amplitude and frequency content owing to acoustic impedance difference between soil and bedrock. Firstly, shear <span class="hlt">wave</span> velocity and depth information of layers on bedrock is needed to detect this changing. Shear <span class="hlt">wave</span> velocity can be obtained using inversion of Rayleigh <span class="hlt">wave</span> dispersion curves obtained from surface <span class="hlt">wave</span> methods (MASW- the Multichannel Analysis of Surface <span class="hlt">Waves</span>, ReMi-Refraction Microtremor, SPAC-Spatial Autocorrelation). While research depth is limeted in active source study, a passive source methods are utilized formore » deep depth which is not reached using active source methods. ReMi method is used to determine layer thickness and velocity up to 100 m using seismic refraction measurement systems.The research carried out up to desired depth depending on radius using SPAC which is utilized easily in conditions that district using of seismic studies in the city. Vs profiles which are required to calculate deformations in under static and dynamic loads can be obtained with high resolution using combining rayleigh <span class="hlt">wave</span> dispersion curve obtained from active and passive source methods. In the this study, Surface <span class="hlt">waves</span> data were collected using the measurements of MASW, ReMi and SPAC at the İzmir Bornova region. Dispersion curves obtained from surface <span class="hlt">wave</span> methods were combined in wide frequency band and Vs-depth profiles were obtained using inversion. Reliability of the resulting soil profiles were provided by comparison with theoretical transfer function obtained from soil paremeters and observed soil transfer function from Nakamura technique and by examination of fitting between these functions. Vs values are changed between 200-830 m/s and engineering bedrock (Vs>760 m/s) depth is approximately 150 m.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EPSC...11....7A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EPSC...11....7A"><span>Luminosity <span class="hlt">variations</span> of protostars at the Hayashi stage</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Abdulmyanov, T. R.</p> <p>2017-09-01</p> <p>In the present paper, the luminosity <span class="hlt">variations</span> of protostars at the Hayashi stage are considered. According to the density <span class="hlt">wave</span> model, the luminosity of protostars will have significant <span class="hlt">variations</span> throughout the Hayashi stage. The initial moments of the formation of protoplanetary rings of the Solar system and the luminosity of the protostar for these moments are obtained.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012GeoRL..3919105P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012GeoRL..3919105P"><span>Infrasonic <span class="hlt">waves</span> generated by supersonic auroral arcs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pasko, Victor P.</p> <p>2012-10-01</p> <p>A finite-difference time-domain (FDTD) model of infrasound propagation in a realistic atmosphere is used to provide quantitative interpretation of infrasonic <span class="hlt">waves</span> produced by auroral arcs moving with supersonic speed. The Lorentz force and Joule heating are discussed in the existing literature as primary sources producing infrasound <span class="hlt">waves</span> in the frequency range 0.1-0.01 Hz associated with the auroral electrojet. The results are consistent with original ideas of Swift (1973) and demonstrate that the synchronization of the speed of auroral arc and phase speed of the acoustic <span class="hlt">wave</span> in the electrojet volume is an important condition for generation of magnitudes and frequency contents of infrasonic <span class="hlt">waves</span> observable on the ground. The reported modeling also allows <span class="hlt">accurate</span> quantitative reproduction of previously observed complex infrasonic waveforms including direct shock and reflected shockwaves, which are refracted back to the earth by the thermosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950005402','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950005402"><span><span class="hlt">Accurate</span> interlaminar stress recovery from finite element analysis</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Tessler, Alexander; Riggs, H. Ronald</p> <p>1994-01-01</p> <p>The accuracy and robustness of a two-dimensional smoothing methodology is examined for the problem of recovering <span class="hlt">accurate</span> interlaminar shear stress distributions in laminated composite and sandwich plates. The smoothing methodology is based on a <span class="hlt">variational</span> formulation which combines discrete least-squares and penalty-constraint functionals in a single <span class="hlt">variational</span> form. The smoothing analysis utilizes optimal strains computed at discrete locations in a finite element analysis. These discrete strain data are smoothed with a smoothing element discretization, producing superior accuracy strains and their first gradients. The approach enables the resulting smooth strain field to be practically C1-continuous throughout the domain of smoothing, exhibiting superconvergent properties of the smoothed quantity. The continuous strain gradients are also obtained directly from the solution. The recovered strain gradients are subsequently employed in the integration o equilibrium equations to obtain <span class="hlt">accurate</span> interlaminar shear stresses. The problem is a simply-supported rectangular plate under a doubly sinusoidal load. The problem has an exact analytic solution which serves as a measure of goodness of the recovered interlaminar shear stresses. The method has the versatility of being applicable to the analysis of rather general and complex structures built of distinct components and materials, such as found in aircraft design. For these types of structures, the smoothing is achieved with 'patches', each patch covering the domain in which the smoothed quantity is physically continuous.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MS%26E..339a2007Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MS%26E..339a2007Z"><span>Identification of moving sinusoidal <span class="hlt">wave</span> loads for sensor structural configuration by finite element inverse method</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, B.; Yu, S.</p> <p>2018-03-01</p> <p>In this paper, a beam structure of composite materials with elastic foundation supports is established as the sensor model, which propagates moving sinusoidal <span class="hlt">wave</span> loads. The inverse Finite Element Method (iFEM) is applied for reconstructing moving <span class="hlt">wave</span> loads which are compared with true <span class="hlt">wave</span> loads. The conclusion shows that iFEM is <span class="hlt">accurate</span> and robust in the determination of <span class="hlt">wave</span> propagation. This helps to seek a suitable new <span class="hlt">wave</span> sensor method.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017InJPh..91.1395B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017InJPh..91.1395B"><span><span class="hlt">Wave</span> equations on anti self dual (ASD) manifolds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bashingwa, Jean-Juste; Kara, A. H.</p> <p>2017-11-01</p> <p>In this paper, we study and perform analyses of the <span class="hlt">wave</span> equation on some manifolds with non diagonal metric g_{ij} which are of neutral signatures. These include the invariance properties, <span class="hlt">variational</span> symmetries and conservation laws. In the recent past, <span class="hlt">wave</span> equations on the standard (space time) Lorentzian manifolds have been performed but not on the manifolds from metrics of neutral signatures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.S11A2426W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.S11A2426W"><span>The exploration technology and application of sea surface <span class="hlt">wave</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Y.</p> <p>2016-12-01</p> <p>In order to investigate the seismic velocity structure of the shallow sediments in the Bohai Sea of China, we conduct a shear-<span class="hlt">wave</span> velocity inversion of the surface <span class="hlt">wave</span> dispersion data from a survey of 12 ocean bottom seismometers (OBS) and 377 shots of a 9000 inch3 air gun. With OBS station spacing of 5 km and air gun shot spacing of 190 m, high-quality Rayleigh <span class="hlt">wave</span> data were recorded by the OBSs within 0.4 5 km offset. Rayleigh <span class="hlt">wave</span> phase velocity dispersion for the fundamental mode and first overtone in the frequency band of 0.9 3.0 Hz were retrieved with the phase-shift method and inverted for the shear-<span class="hlt">wave</span> velocity structure of the shallow sediments with a damped iterative least-square algorithm. Pseudo 2-D shear-<span class="hlt">wave</span> velocity profiles with depth to 400 m show coherent features of relatively weak lateral velocity <span class="hlt">variation</span>. The uncertainty in shear-<span class="hlt">wave</span> velocity structure was also estimated based on the pseudo 2-D profiles from 6 trial inversions with different initial models, which suggest a velocity uncertainty < 30 m/s for most parts of the 2-D profiles. The layered structure with little lateral <span class="hlt">variation</span> may be attributable to the continuous sedimentary environment in the Cenozoic sedimentary basin of the Bohai Bay basin. The shear-<span class="hlt">wave</span> velocity of 200 300 m/s in the top 100 m of the Bohai Sea floor may provide important information for offshore site response studies in earthquake engineering. Furthermore, the very low shear-<span class="hlt">wave</span> velocity structure (200 700 m/s) down to 400 m depth could produce a significant travel time delay of 1 s in the S <span class="hlt">wave</span> arrivals, which needs to be considered to avoid serious bias in S <span class="hlt">wave</span> traveltime tomographic models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016WRR....52.5248M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016WRR....52.5248M"><span>Dynamic groundwater flows and geochemistry in a sandy nearshore aquifer over a <span class="hlt">wave</span> event</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Malott, Spencer; O'Carroll, Denis M.; Robinson, Clare E.</p> <p>2016-07-01</p> <p>Dynamic coastal forcing influences the transport of pollutants in nearshore aquifers and their ultimate flux to coastal waters. In this study, field data are presented that show, for the first time, the influence of a period of intensified <span class="hlt">wave</span> conditions (<span class="hlt">wave</span> event) on nearshore groundwater flows and geochemistry in a sandy beach. Field measurements at a freshwater beach allow <span class="hlt">wave</span> effects to be quantified without other complex forcing that are present along marine shorelines (e.g., tides). Pressure transducer data obtained over an isolated <span class="hlt">wave</span> event reveal the development of transient groundwater flow recirculations. The groundwater flows were simulated in FEFLOW using a phase-averaged <span class="hlt">wave</span> setup approach to represent <span class="hlt">waves</span> acting on the sediment-water interface. Comparison of measured and simulated data indicates that consideration of <span class="hlt">wave</span> setup alone is able to adequately capture <span class="hlt">wave</span>-induced perturbations in groundwater flows. While prior studies have shown sharp pH and redox spatial zonations in nearshore aquifers, this study reveals rapid temporal <span class="hlt">variations</span> in conductivity, pH, and redox (ORP) in shallow sediments (up to 0.5 m depth) in response to varying <span class="hlt">wave</span> conditions. Comparison of head gradients with calculated conductivity and pH mixing ratios indicates the controlling effect of the <span class="hlt">wave</span>-induced water exchange and flows in driving the observed geochemical dynamics. While we are not able to conclusively determine the extent to which temporal <span class="hlt">variations</span> are caused by conservative mixing versus reactive processes, the pH and ORP <span class="hlt">variations</span> observed will have significant implications for the fate of reactive pollutants discharging through sandy nearshore aquifers.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApGeo..13..375Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApGeo..13..375Z"><span>Digital core based transmitted ultrasonic <span class="hlt">wave</span> simulation and velocity accuracy analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhu, Wei; Shan, Rui</p> <p>2016-06-01</p> <p>Transmitted ultrasonic <span class="hlt">wave</span> simulation (TUWS) in a digital core is one of the important elements of digital rock physics and is used to study <span class="hlt">wave</span> propagation in porous cores and calculate equivalent velocity. When simulating <span class="hlt">wave</span> propagates in a 3D digital core, two additional layers are attached to its two surfaces vertical to the <span class="hlt">wave</span>-direction and one planar <span class="hlt">wave</span> source and two receiver-arrays are properly installed. After source excitation, the two receivers then record incident and transmitted <span class="hlt">waves</span> of the digital rock. <span class="hlt">Wave</span> propagating velocity, which is the velocity of the digital core, is computed by the picked peak-time difference between the two recorded <span class="hlt">waves</span>. To evaluate the accuracy of TUWS, a digital core is fully saturated with gas, oil, and water to calculate the corresponding velocities. The velocities increase with decreasing <span class="hlt">wave</span> frequencies in the simulation frequency band, and this is considered to be the result of scattering. When the pore fluids are varied from gas to oil and finally to water, the velocity-<span class="hlt">variation</span> characteristics between the different frequencies are similar, thereby approximately following the <span class="hlt">variation</span> law of velocities obtained from linear elastic statics simulation (LESS), although their absolute values are different. However, LESS has been widely used. The results of this paper show that the transmission ultrasonic simulation has high relative precision.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20170009019','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20170009019"><span>Properties, Propagation, and Excitation of EMIC <span class="hlt">Waves</span> Properties, Propagation, and Excitation of EMIC <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zhang, Jichun; Coffey, Victoria N.; Chandler, Michael O.; Boardsen, Scott A.; Saikin, Anthony A.; Mello, Emily M.; Russell, Christopher T.; Torbert, Roy B.; Fuselier, Stephen A.; Giles, Barbara L.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20170009019'); toggleEditAbsImage('author_20170009019_show'); toggleEditAbsImage('author_20170009019_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20170009019_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20170009019_hide"></p> <p>2017-01-01</p> <p>Electromagnetic ion cyclotron (EMIC) <span class="hlt">waves</span> (0.1-5 Hz) play an important role in particle dynamics in the Earth's magnetosphere. EMIC <span class="hlt">waves</span> are preferentially excited in regions where hot anisotropic ions and cold dense plasma populations spatially overlap. While the generation region of EMIC <span class="hlt">waves</span> is usually on or near the magnetic equatorial plane in the inner magnetosphere, EMIC <span class="hlt">waves</span> have both equatorial and off-equator source regions on the dayside in the compressed outer magnetosphere. Using field and plasma measurements from the Magnetospheric Multiscale (MMS) mission, we perform a case study of EMIC <span class="hlt">waves</span> and associated local plasma conditions observed on 19 October 2015. From 0315 to 0810 UT, before crossing the magnetopause into the magnetosheath, all four MMS spacecraft detected long-lasting He(exp +)-band EMIC <span class="hlt">wave</span> emissions around local noon (MLT = 12.7 - 14.0) at high L-shells (L = 8.8 - 15.2) and low magnetic latitudes (MLAT = -21.8deg - -30.3deg). Energetic (greater than 1 keV) and anisotropic ions were present throughout this event that was in the recovery phase of a weak geomagnetic storm (min. Dst = -48 nT at 1000 UT on 18 October 2015). The testing of linear theory suggests that the EMIC <span class="hlt">waves</span> were excited locally. Although the <span class="hlt">wave</span> event is dominated by small normal angles, its polarization is mixed with right- and left-handedness and its propagation is bi-directional with regard to the background magnetic field. The short inter-spacecraft distances (as low as 15 km) of the MMS mission make it possible to <span class="hlt">accurately</span> determine the k vector of the <span class="hlt">waves</span> using the phase difference technique. Preliminary analysis finds that the k vector magnitude, phase speed, and wavelength of the 0.3-Hz <span class="hlt">wave</span> packet at 0453:55 UT are 0.005 km(exp -1), 372.9 km/s, and 1242.9 km, respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/21024554-solving-schroedinger-equation-atoms-molecules-without-analytical-integration-based-free-iterative-complement-interaction-wave-function','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/21024554-solving-schroedinger-equation-atoms-molecules-without-analytical-integration-based-free-iterative-complement-interaction-wave-function"><span>Solving the Schroedinger Equation of Atoms and Molecules without Analytical Integration Based on the Free Iterative-Complement-Interaction <span class="hlt">Wave</span> Function</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Nakatsuji, H.; Nakashima, H.; Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510</p> <p>2007-12-14</p> <p>A local Schroedinger equation (LSE) method is proposed for solving the Schroedinger equation (SE) of general atoms and molecules without doing analytic integrations over the complement functions of the free ICI (iterative-complement-interaction) <span class="hlt">wave</span> functions. Since the free ICI <span class="hlt">wave</span> function is potentially exact, we can assume a flatness of its local energy. The <span class="hlt">variational</span> principle is not applicable because the analytic integrations over the free ICI complement functions are very difficult for general atoms and molecules. The LSE method is applied to several 2 to 5 electron atoms and molecules, giving an accuracy of 10{sup -5} Hartree in total energy.more » The potential energy curves of H{sub 2} and LiH molecules are calculated precisely with the free ICI LSE method. The results show the high potentiality of the free ICI LSE method for developing <span class="hlt">accurate</span> predictive quantum chemistry with the solutions of the SE.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018IzAOP..54..173Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018IzAOP..54..173Z"><span>The Effect of Internal Gravity <span class="hlt">Waves</span> on Fluctuations in Meteorological Parameters of the Atmospheric Boundary Layer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zaitseva, D. V.; Kallistratova, M. A.; Lyulyukin, V. S.; Kouznetsov, R. D.; Kuznetsov, D. D.</p> <p>2018-03-01</p> <p><span class="hlt">Variations</span> in the intensity of turbulence during <span class="hlt">wave</span> activity in the stable atmospheric boundary layer over a homogeneous steppe surface have been analyzed. Eight <span class="hlt">wave</span> activity episodes recorded with a Doppler sodar in August 2015 at the Tsimlyansk Scientific Station of the Obukhov Institute of Atmospheric Physics have been studied. These episodes include seven trains of Kelvin-Helmholtz <span class="hlt">waves</span> and one train of buoyancy <span class="hlt">waves</span>. <span class="hlt">Variations</span> in the rms deviation of the vertical wind-velocity component, the temperature structure parameter, and vertical heat and momentum fluxes have been estimated for each episode of <span class="hlt">wave</span> activity. It has been found that Kelvin-Helmholtz <span class="hlt">waves</span> slightly affect the intensity of turbulence, while buoyancy <span class="hlt">waves</span> cause the temperature structure parameter and the vertical fluxes to increase by more than an order of magnitude.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AdSpR..54.1326V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AdSpR..54.1326V"><span>Shape modeling with family of Pearson distributions: Langmuir <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vidojevic, Sonja</p> <p>2014-10-01</p> <p>Two major effects of Langmuir <span class="hlt">wave</span> electric field influence on spectral line shapes are appearance of depressions shifted from unperturbed line and an additional dynamical line broadening. More realistic and <span class="hlt">accurate</span> models of Langmuir <span class="hlt">waves</span> are needed to study these effects with more confidence. In this article we present distribution shapes of a high-quality data set of Langmuir <span class="hlt">waves</span> electric field observed by the WIND satellite. Using well developed numerical techniques, the distributions of the empirical measurements are modeled by family of Pearson distributions. The results suggest that the existing theoretical models of energy conversion between an electron beam and surrounding plasma is more complex. If the processes of the Langmuir <span class="hlt">wave</span> generation are better understood, the influence of Langmuir <span class="hlt">waves</span> on spectral line shapes could be modeled better.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22663366-gravitational-waves-from-stellar-black-hole-binaries-impact-nearby-sun-like-stars','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22663366-gravitational-waves-from-stellar-black-hole-binaries-impact-nearby-sun-like-stars"><span>Gravitational <span class="hlt">Waves</span> from Stellar Black Hole Binaries and the Impact on Nearby Sun-like Stars</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Lopes, Ilídio; Silk, Joseph, E-mail: ilidio.lopes@tecnico.ulisboa.pt, E-mail: silk@astro.ox.ac.uk</p> <p></p> <p>We investigate the impact of resonant gravitational <span class="hlt">waves</span> on quadrupole acoustic modes of Sun-like stars located nearby stellar black hole binary systems (such as GW150914 and GW151226). We find that the stimulation of the low-overtone modes by gravitational radiation can lead to sizeable photometric amplitude <span class="hlt">variations</span>, much larger than the predictions for amplitudes driven by turbulent convection, which in turn are consistent with the photometric amplitudes observed in most Sun-like stars. For <span class="hlt">accurate</span> stellar evolution models, using up-to-date stellar physics, we predict photometric amplitude <span class="hlt">variations</span> of 1–10{sup 3} ppm for a solar mass star located at a distance between 1more » au and 10 au from the black hole binary and belonging to the same multi-star system. The observation of such a phenomenon will be within the reach of the Plato mission because the telescope will observe several portions of the Milky Way, many of which are regions of high stellar density with a substantial mixed population of Sun-like stars and black hole binaries.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920024703','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920024703"><span>On the physics of <span class="hlt">waves</span> in the solar atmosphere: <span class="hlt">Wave</span> heating and wind acceleration</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Musielak, Z. E.</p> <p>1992-01-01</p> <p>In the area of solar physics, new calculations of the acoustic <span class="hlt">wave</span> energy fluxes generated in the solar convective zone was performed. The original theory developed was corrected by including a new frequency factor describing temporal <span class="hlt">variations</span> of the turbulent energy spectrum. We have modified the original Stein code by including this new frequency factor, and tested the code extensively. Another possible source of the mechanical energy generated in the solar convective zone is the excitation of magnetic flux tube <span class="hlt">waves</span> which can carry energy along the tubes far away from the region. The problem as to how efficiently those <span class="hlt">waves</span> are generated in the Sun was recently solved. The propagation of nonlinear magnetic tube <span class="hlt">waves</span> in the solar atmosphere was calculated, and mode coupling, shock formation, and heating of the local medium was studied. The <span class="hlt">wave</span> trapping problems and evaluation of critical frequencies for <span class="hlt">wave</span> reflection in the solar atmosphere was studied. It was shown that the role played by Alfven <span class="hlt">waves</span> in the wind accelerations and the coronal hole heating is dominant. Presently, we are performing calculations of <span class="hlt">wave</span> energy fluxes generated in late-type dwarf stars and studying physical processes responsible for the heating of stellar chromospheres and coronae. In the area of physics of <span class="hlt">waves</span>, a new analytical approach for studying linear Alfven <span class="hlt">waves</span> in smoothly nonuniform media was recently developed. This approach is presently being extended to study the propagation of linear and nonlinear magnetohydrodynamic (MHD) <span class="hlt">waves</span> in stratified, nonisothermal and solar atmosphere. The Lighthill theory of sound generation to nonisothermal media (with a special temperature distribution) was extended. Energy cascade by nonlinear MHD <span class="hlt">waves</span> and possible chaos driven by these <span class="hlt">waves</span> are presently considered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.9546Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.9546Z"><span>Unusual properties of high-compliance porosity extracted from measurements of pressure-dependent <span class="hlt">wave</span> velocities in rocks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zaitsev, Vladimir Y.; Radostin, Andrey V.; Pasternak, Elena; Dyskin, Arcady</p> <p>2016-04-01</p> <p>Conventionally the interpretation of <span class="hlt">wave</span> velocities and their <span class="hlt">variations</span> under load is conducted assuming that closable cracks have simple planar shapes, like the popular model of penny-shape cracks. For such cracks, the proportion between complementary <span class="hlt">variations</span> in different elastic parameters of rocks (such as S- and P-<span class="hlt">wave</span> velocities) is strictly pre-determined, in particular, it is independent of the crack aspect ratio and rather weakly dependent on the Poisson's ratio of the intact rock. Real rocks, however, contain multitude of cracks of different geometry. Faces of such cracks can exhibit complex modes of interaction when closed by external load, which may result in very different ratios between normal- and shear compliances of such defects. In order to describe the reduction of different elastic moduli, we propose a model in which the compliances of crack-like defects are explicitly decoupled and are not predetermined, so that the ratio q between total normal- and shear- compliances imparted to the rock mass (as well as individual values of these compliances) can be estimated from experimental data on reduction of different elastic moduli (e.g., pressure dependences of P- and S-<span class="hlt">wave</span> velocities). Physically, the so-extracted ratio q can be interpreted as intrinsic property of individual crack-like defects similar to each other, or as a characteristic of proportion between concentrations of pure normal cracks with very large q and pure shear cracks with q→0. The latter case can correspond, e.g., to saturated cracks in which weakly-compressible liquid prevents crack closing under normal loading. It can be shown that for conventional dry planar cracks, the compliance ratio is q ˜2. The developed model applied to the data on <span class="hlt">wave</span>-velocity <span class="hlt">variations</span> with external pressure indicates that elastic properties of the real crack-like defects in rocks can differ considerably from the usually assumed ones. Comparison with experimental data on <span class="hlt">variations</span> P- and S-<span class="hlt">wave</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018SPIE10615E..2MS','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018SPIE10615E..2MS"><span>Total generalized <span class="hlt">variation</span>-regularized <span class="hlt">variational</span> model for single image dehazing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shu, Qiao-Ling; Wu, Chuan-Sheng; Zhong, Qiu-Xiang; Liu, Ryan Wen</p> <p>2018-04-01</p> <p>Imaging quality is often significantly degraded under hazy weather condition. The purpose of this paper is to recover the latent sharp image from its hazy version. It is well known that the <span class="hlt">accurate</span> estimation of depth information could assist in improving dehazing performance. In this paper, a detail-preserving <span class="hlt">variational</span> model was proposed to simultaneously estimate haze-free image and depth map. In particular, the total <span class="hlt">variation</span> (TV) and total generalized <span class="hlt">variation</span> (TGV) regularizers were introduced to restrain haze-free image and depth map, respectively. The resulting nonsmooth optimization problem was efficiently solved using the alternating direction method of multipliers (ADMM). Comprehensive experiments have been conducted on realistic datasets to compare our proposed method with several state-of-the-art dehazing methods. Results have illustrated the superior performance of the proposed method in terms of visual quality evaluation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AIPC.1949r0003Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AIPC.1949r0003Y"><span>Welding induced residual stress evaluation using laser-generated Rayleigh <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ye, Chong; Zhou, Yuanlai; Reddy, Vishnu V. B.; Mebane, Aaron; Ume, I. Charles</p> <p>2018-04-01</p> <p>Welding induced residual stress could affect the dimensional stability, fatigue life, and chemical resistance of the weld joints. Ultrasonic method serves as an important non-destructive tool for the residual stress evaluation due to its easy implementation, low cost and wide application to different materials. Residual stress would result in the ultrasonic <span class="hlt">wave</span> velocity <span class="hlt">variation</span>, which is the so called acoustoelastic effect. In this paper, Laser/EMAT ultrasonic technique was proposed to experimentally study the relative velocity <span class="hlt">variation</span> ΔV/V of Rayleigh <span class="hlt">wave</span>, which has the potential to evaluate surface/subsurface longitudinal residual stress developed during the Gas Metal Arc Welding process. Broad band ultrasonic <span class="hlt">waves</span> were excited by pulsed Q-Switched Nd: YAG laser. An electromagnetic acoustic transducer (EMAT) attached to the welded plates was used to capture the Rayleigh <span class="hlt">wave</span> signals propagating along the weld seam direction. Different time of flight measurements were conducted by varying the distance between the weld seam and Rayleigh <span class="hlt">wave</span> propagating path in the range of 0 to 45 mm. The maximum relative velocity difference was found on the weld seam. With the increasing distance away from the weld seam, the relative velocity difference sharply decreased to negative value. With further increase in distance, the relative velocity difference slowly increased and approached zero. The distribution of relative velocity <span class="hlt">variations</span> indicates that tensile stress appears in the melted zone as it becomes compressive near the heat-affected zone.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=SOAP&pg=4&id=EJ830502','ERIC'); return false;" href="https://eric.ed.gov/?q=SOAP&pg=4&id=EJ830502"><span>Visualization of Sound <span class="hlt">Waves</span> Using Regularly Spaced Soap Films</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Elias, F.; Hutzler, S.; Ferreira, M. S.</p> <p>2007-01-01</p> <p>We describe a novel demonstration experiment for the visualization and measurement of standing sound <span class="hlt">waves</span> in a tube. The tube is filled with equally spaced soap films whose thickness varies in response to the amplitude of the sound <span class="hlt">wave</span>. The thickness <span class="hlt">variations</span> are made visible based on optical interference. The distance between two antinodes is…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22254284','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22254284"><span><span class="hlt">Variation</span> of <span class="hlt">wave</span> speed determined by the PU-loop with proximity to a reflection site.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Ye; Borlotti, Alessandra; Parker, Kim H; Khir, Ashraf W</p> <p>2011-01-01</p> <p><span class="hlt">Wave</span> speed is directly related to arterial distensibility and is widely used by clinicians to assess arterial stiffness. The PU-loop method for determining <span class="hlt">wave</span> speed is based on the water hammer equation for flow in flexible tubes and artery using the method of characteristics. This technique determines <span class="hlt">wave</span> speed using simultaneous measurements of pressure and velocity at a single point. The method shows that during the early part of systole, the relationship between pressure and velocity is generally linear, and the initial slope of the PU-loop is proportional to <span class="hlt">wave</span> speed. In this work, we designed an in-vitro experiment to investigate the effect of proximity to a reflection site on the <span class="hlt">wave</span> speed determined by the PU-loop through varying the distance between the measurement and reflection sites. Measurements were made in a flexible tube with a reflection site at the distal end formed by joining the tube to another tube with a different diameter and material properties. Six different flexible tubes were used to generate both positive and negative reflection coefficients of different magnitudes. We found that the <span class="hlt">wave</span> speed determined by the PU-loop did not change when the measurement site was far from the reflection site but did change as the distance to the reflection site decreased. The calculated <span class="hlt">wave</span> speed increased with positive reflections and decreased with negative reflections. The magnitude of the change in <span class="hlt">wave</span> speed at a fixed distance from the reflection site increased with increasing the value of the reflection coefficient.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996APS..MAY..G501W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996APS..MAY..G501W"><span>Gravitational <span class="hlt">waves</span> and the death-dance of compact stellar binaries</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Will, Clifford M.</p> <p>1996-05-01</p> <p>The completion of a network of advanced laser-interferometric gravitational-<span class="hlt">wave</span> observatories (US LIGO and European VIRGO projects) around 2001 will make possible the study of the inspiral and coalescence of binary systems of compact objects (neutron stars and black holes), using gravitational radiation. To extract useful information from the <span class="hlt">waves</span>, such as the masses and spins of the bodies, theoretical general relativistic gravitational waveforms will be used as templates, cross-correlated against the detector output, in a matched filtering process. Because the broad-band detectors will be very sensitive to the non-linearly evolving phase of the <span class="hlt">waves</span>, the templates must be extremely <span class="hlt">accurate</span> in their treatment of the gravitational back-reaction on the orbital frequency, probably as <span class="hlt">accurate</span> as O[(v/c)^6] beyond the predictions of the quadrupole formula. This presents a major challenge to theorists. Recently, templates <span class="hlt">accurate</span> to O[(v/c)^4] were obtained by two independent methods (L. Blanchet, T. Damour, B. R. Iyer, C. M. Will and A. G. Wiseman, Phys. Rev. Lett. 74), 3515 (1995), and extensions to O[(v/c)^5] and higher are in progress. We summarize one of these methods, which extends and improves an earlier framework due to Epstein and Wagoner (R. Epstein and R. V. Wagoner, Astrophys. J. 210), 764 (1975), in which Einstein's equations are recast as a flat spacetime <span class="hlt">wave</span> equation with source comprised of matter confined to compact regions and gravitational non-linearities extending to infinity. The new method (C. M. Will and A. G. Wiseman, Phys. Rev. D, submitted), carried through O[(v/c)^4], is free of divergences or undefined integrals, correctly predicts all gravitational <span class="hlt">wave</span> ``tail'' effects caused by backscatter of the outgoing radiation off the background curved spacetime, and yields radiation that propagates asymptotically along true null cones of the curved spacetime.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018DDA....4910002H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018DDA....4910002H"><span>Axisymmetric Density <span class="hlt">Waves</span> in Saturn's Rings</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hedman, Matthew; Nicholson, Philip</p> <p>2018-04-01</p> <p>Density <span class="hlt">waves</span> in Saturn's rings are typically tightly wrapped spiral patterns generated by resonances with either Saturn's moons or structures inside the planet. However, between the Barnard and Bessel Gaps in the Cassini Division (i.e. between 120,240 and 120,300 km), there are density <span class="hlt">variations</span> that appear to form an axisymmetric density <span class="hlt">wave</span>, which consists of concentric regions of varying density that propagate radially through the rings. Such a <span class="hlt">wave</span> requires some process that forces ring particles at all longitudes to pass through pericenter at the same time, and so cannot be generated by satellite resonances. Instead this particular <span class="hlt">wave</span> appears to be excited by interference between a nearby satellite resonance and normal mode oscillations on the inner edge of the Barnard Gap. Similar axisymmetric <span class="hlt">waves</span> may exist within the Dawes ringlet and the outermost part of the B ring, which are also just interior to resonantly confined edges that exhibit a large number of normal modes. These <span class="hlt">waves</span> may therefore provide new insights into how resonant perturbations near an edge can propagate through a disk of material.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2687650','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2687650"><span>Reproducibility of Regional Pulse <span class="hlt">Wave</span> Velocity in Healthy Subjects</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Lee, Nak Bum</p> <p>2009-01-01</p> <p>Background/Aims Despite the clinical importance and widespread use of pulse <span class="hlt">wave</span> velocity (PWV), there are no standards for pulse sensors or for system requirements to ensure <span class="hlt">accurate</span> pulse <span class="hlt">wave</span> measurement. We assessed the reproducibility of PWV values using a newly developed PWV measurement system. Methods The system used in this study was the PP-1000, which simultaneously provides regional PWV values from arteries at four different sites (carotid, femoral, radial, and dorsalis pedis). Seventeen healthy male subjects without any cardiovascular disease participated in this study. Two observers performed two consecutive measurements in the same subject in random order. To evaluate the reproducibility of the system, two sets of analyses (within-observer and between-observer) were performed. Results The means±SD of PWV for the aorta, arm, and leg were 7.0±1.48, 8.43±1.14, and 8.09±0.98 m/s as measured by observer A and 6.76±1.00, 7.97±0.80, and 7.97±0.72 m/s by observer B, respectively. Between-observer differences for the aorta, arm, and leg were 0.14±0.62, 0.18±0.84, and 0.07±0.86 m/s, respectively, and the correlation coefficients were high, especially for aortic PWV (r=0.93). All the measurements showed significant correlation coefficients, ranging from 0.94 to 0.99. Conclusions The PWV measurement system used in this study provides <span class="hlt">accurate</span> analysis results with high reproducibility. It is necessary to provide an <span class="hlt">accurate</span> algorithm for the detection of additional features such as flow <span class="hlt">wave</span>, reflection <span class="hlt">wave</span>, and dicrotic notch from a pulse waveform. PMID:19270477</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19800002061&hterms=linear+motor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dlinear%2Bmotor','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19800002061&hterms=linear+motor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dlinear%2Bmotor"><span>Some problems of nonlinear <span class="hlt">waves</span> in solid propellant rocket motors</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Culick, F. E. C.</p> <p>1979-01-01</p> <p>An approximate technique for analyzing nonlinear <span class="hlt">waves</span> in solid propellant rocket motors is presented which inexpensively provides <span class="hlt">accurate</span> results up to amplitudes of ten percent. The connection with linear stability analysis is shown. The method is extended to third order in the amplitude of <span class="hlt">wave</span> motion in order to study nonlinear stability, or triggering. Application of the approximate method to the behavior of pulses is described.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830005505','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830005505"><span>Further SEASAT SAR coastal ocean <span class="hlt">wave</span> analysis</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kasischke, E. S.; Shuchman, R. A.; Meadows, G. A.; Jackson, P. L.; Tseng, Y.</p> <p>1981-01-01</p> <p>Analysis techniques used to exploit SEASAT synthetic aperture radar (SAR) data of gravity <span class="hlt">waves</span> are discussed and the SEASAT SAR's ability to monitor large scale <span class="hlt">variations</span> in gravity <span class="hlt">wave</span> fields in both deep and shallow water is evaluated. The SAR analysis techniques investigated included motion compensation adjustments and the semicausal model for spectral analysis of SAR <span class="hlt">wave</span> data. It was determined that spectra generated from fast Fourier transform analysis (FFT) of SAR <span class="hlt">wave</span> data were not significantly altered when either range telerotation adjustments or azimuth focus shifts were used during processing of the SAR signal histories, indicating that SEASAT imagery of gravity <span class="hlt">waves</span> is not significantly improved or degraded by motion compensation adjustments. Evaluation of the semicausal (SC) model using SEASAT SAR data from Rev. 974 indicates that the SC spectral estimates were not significantly better than the FFT results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=Free+AND+energy&pg=6&id=EJ1142565','ERIC'); return false;" href="https://eric.ed.gov/?q=Free+AND+energy&pg=6&id=EJ1142565"><span>Standing <span class="hlt">Waves</span> in an Elastic Spring: A Systematic Study by Video Analysis</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Rodrigues Ventura, Daniel; Simeão de Carvalho, Paulo; Adriano Dias, Marco</p> <p>2017-01-01</p> <p>The word "<span class="hlt">wave</span>" is part of the daily language of every student. However, the physical understanding of the concept demands a high level of abstract thought. In physics, <span class="hlt">waves</span> are oscillating <span class="hlt">variations</span> of a physical quantity that involve the transfer of energy from one point to another, without displacement of matter. A <span class="hlt">wave</span> can be…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19024446','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19024446"><span>[Research on a non-invasive pulse <span class="hlt">wave</span> detection and analysis system].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Ting; Yu, Gang</p> <p>2008-10-01</p> <p>A novel non-invasive pulse <span class="hlt">wave</span> detection and analysis system has been developed, including the software and the hardware. Bi-channel signals can be acquired, stored and shown on the screen dynamically at the same time. Pulse <span class="hlt">wave</span> can be reshown and printed after pulse <span class="hlt">wave</span> analysis and pulse <span class="hlt">wave</span> velocity analysis. This system embraces a computer which is designed for fast data saving, analyzing and processing, and a portable data sampling machine which is based on a singlechip. Experimental results have shown that the system is stable and easy to use, and the parameters are calculated <span class="hlt">accurately</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4241942','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4241942"><span>Investigating the thermally induced acoustoelastic effect in isotropic media with Lamb <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Dodson, Jacob C.; Inman, Daniel J.</p> <p>2014-01-01</p> <p>Elastic <span class="hlt">wave</span> velocities in metallic structures are affected by <span class="hlt">variations</span> in environmental conditions such as changing temperature. This paper extends the theory of acoustoelasticity by allowing thermally induced strains in unconstrained isotropic media, and it experimentally examines the velocity <span class="hlt">variation</span> of Lamb <span class="hlt">waves</span> in aluminum plates (AL-6061) due to isothermal temperature deviations. This paper presents both thermally induced acoustoelastic constants and thermally varying effective Young's modulus and Poisson's ratio which include the third order elastic material constants. The experimental thermal sensitivity of the phase velocity (∂vP/∂θ) for both the symmetric and antisymmetric modes are bounded by two theories, the acoustoelastic Lamb <span class="hlt">wave</span> theory with thermo-acoustoelastic tensors and the thermoelastic Lamb <span class="hlt">wave</span> theory using an effective thermo-acoustoelastic moduli. This paper shows the theoretical thermally induced acoustoelastic Lamb <span class="hlt">wave</span> thermal sensitivity (∂vP/∂θ) is an upper bound approximation of the experimental thermal changes, but the acoustoelastic Lamb <span class="hlt">wave</span> theory is not valid for predicting the antisymmetric (A0) phase velocity at low frequency-thickness values, <1.55 MHz mm for various temperatures. PMID:25373955</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940008583','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940008583"><span>Quantitative Mapping of Pore Fraction <span class="hlt">Variations</span> in Silicon Nitride Using an Ultrasonic Contact Scan Technique</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Roth, Don J.; Kiser, James D.; Swickard, Suzanne M.; Szatmary, Steven A.; Kerwin, David P.</p> <p>1993-01-01</p> <p>An ultrasonic scan procedure using the pulse-echo contact configuration was employed to obtain maps of pore fraction <span class="hlt">variations</span> in sintered silicon nitride samples in terms of ultrasonic material properties. Ultrasonic velocity, attenuation coefficient, and reflection coefficient images were obtained simultaneously over a broad band of frequencies (e.g., 30 to 110 MHz) by using spectroscopic analysis. Liquid and membrane (dry) coupling techniques and longitudinal and shear-<span class="hlt">wave</span> energies were used. The major results include the following: Ultrasonic velocity (longitudinal and shear <span class="hlt">wave</span>) images revealed and correlated with the extent of average through-thickness pore fraction <span class="hlt">variations</span> in the silicon nitride disks. Attenuation coefficient images revealed pore fraction nonuniformity due to the scattering that occurred at boundaries between regions of high and low pore fraction. Velocity and attenuation coefficient images were each nearly identical for machined and polished disks, making the method readily applicable to machined materials. Velocity images were similar for wet and membrane coupling. Maps of apparent Poisson's ratio constructed from longitudinal and shear-<span class="hlt">wave</span> velocities quantified Poisson's ratio <span class="hlt">variations</span> across a silicon nitride disk. Thermal <span class="hlt">wave</span> images of a disk indicated transient thermal behavior <span class="hlt">variations</span> that correlated with observed <span class="hlt">variations</span> in pore fraction and velocity and attenuation coefficients.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19770032365&hterms=IOTA&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DIOTA','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19770032365&hterms=IOTA&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DIOTA"><span>The ultraviolet <span class="hlt">variations</span> of iota Cas</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Molnar, M. R.; Mallama, A. D.; Soskey, D. G.; Holm, A. V.</p> <p>1976-01-01</p> <p>The Ap variable star iota Cas was observed with the photometers on OAO-2 covering the spectral range 1430-4250 A. The ultraviolet light curves show a double <span class="hlt">wave</span> with primary minimum and maximum at phase ? 0.00 and 0.35, respectively. Secondary minimum light is at phase ? 0.65 with secondary maximum at phase ? 0.85. The light curves longward of 3150 A vary in opposition to those shortward of this 'null region'. Ground-based coude spectra show that the Fe II and Cr II line strengths have a double-<span class="hlt">wave</span> <span class="hlt">variation</span> such that maximum strength occurs at minimum ultraviolet light. We suggest that the strong ultraviolet opacities due to photoionization and line blanketing by these metals may cause the observed photometric <span class="hlt">variations</span>. We have also constructed an oblique-rotator model which shows iron and chromium lying in a great circle band rather than in circular spots.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhRvD..96f4016C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhRvD..96f4016C"><span><span class="hlt">Wave</span> scattering in spatially inhomogeneous currents</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Churilov, Semyon; Ermakov, Andrei; Stepanyants, Yury</p> <p>2017-09-01</p> <p>We analytically study a scattering of long linear surface <span class="hlt">waves</span> on stationary currents in a duct (canal) of constant depth and variable width. It is assumed that the background velocity linearly increases or decreases with the longitudinal coordinate due to the gradual <span class="hlt">variation</span> of duct width. Such a model admits an analytical solution of the problem in hand, and we calculate the scattering coefficients as functions of incident <span class="hlt">wave</span> frequency for all possible cases of sub-, super-, and transcritical currents. For completeness we study both cocurrent and countercurrent <span class="hlt">wave</span> propagation in accelerating and decelerating currents. The results obtained are analyzed in application to recent analog gravity experiments and shed light on the problem of hydrodynamic modeling of Hawking radiation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRD..122..699B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRD..122..699B"><span>A stationary phase solution for mountain <span class="hlt">waves</span> with application to mesospheric mountain <span class="hlt">waves</span> generated by Auckland Island</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Broutman, Dave; Eckermann, Stephen D.; Knight, Harold; Ma, Jun</p> <p>2017-01-01</p> <p>A relatively general stationary phase solution is derived for mountain <span class="hlt">waves</span> from localized topography. It applies to hydrostatic, nonhydrostatic, or anelastic dispersion relations, to arbitrary localized topography, and to arbitrary smooth vertically varying background temperature and vector wind profiles. A simple method is introduced to compute the ray Jacobian that quantifies the effects of horizontal geometrical spreading in the stationary phase solution. The stationary phase solution is applied to mesospheric mountain <span class="hlt">waves</span> generated by Auckland Island during the Deep Propagating Gravity <span class="hlt">Wave</span> Experiment. The results are compared to a Fourier solution. The emphasis is on interpretations involving horizontal geometrical spreading. The results show larger horizontal geometrical spreading for nonhydrostatic <span class="hlt">waves</span> than for hydrostatic <span class="hlt">waves</span> in the region directly above the island; the dominant effect of horizontal geometrical spreading in the lower ˜30 km of the atmosphere, compared to the effects of refraction and background density <span class="hlt">variation</span>; and the enhanced geometrical spreading due to directional wind in the approach to a critical layer in the mesosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MNRAS.474.2289P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MNRAS.474.2289P"><span>Phase mixing of Alfvén <span class="hlt">waves</span> in axisymmetric non-reflective magnetic plasma configurations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Petrukhin, N. S.; Ruderman, M. S.; Shurgalina, E. G.</p> <p>2018-02-01</p> <p>We study damping of phase-mixed Alfvén <span class="hlt">waves</span> propagating in non-reflective axisymmetric magnetic plasma configurations. We derive the general equation describing the attenuation of the Alfvén <span class="hlt">wave</span> amplitude. Then we applied the general theory to a particular case with the exponentially divergent magnetic field lines. The condition that the configuration is non-reflective determines the <span class="hlt">variation</span> of the plasma density along the magnetic field lines. The density profiles exponentially decreasing with the height are not among non-reflective density profiles. However, we managed to find non-reflective profiles that fairly well approximate exponentially decreasing density. We calculate the <span class="hlt">variation</span> of the total <span class="hlt">wave</span> energy flux with the height for various values of shear viscosity. We found that to have a substantial amount of <span class="hlt">wave</span> energy dissipated at the lower corona, one needs to increase shear viscosity by seven orders of magnitude in comparison with the value given by the classical plasma theory. An important result that we obtained is that the efficiency of the <span class="hlt">wave</span> damping strongly depends on the density <span class="hlt">variation</span> with the height. The stronger the density decrease, the weaker the <span class="hlt">wave</span> damping is. On the basis of this result, we suggested a physical explanation of the phenomenon of the enhanced <span class="hlt">wave</span> damping in equilibrium configurations with exponentially diverging magnetic field lines.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JPhCS.991a2047K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JPhCS.991a2047K"><span><span class="hlt">Wave</span> propagation problem for a micropolar elastic waveguide</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kovalev, V. A.; Murashkin, E. V.; Radayev, Y. N.</p> <p>2018-04-01</p> <p>A propagation problem for coupled harmonic <span class="hlt">waves</span> of translational displacements and microrotations along the axis of a long cylindrical waveguide is discussed at present study. Microrotations modeling is carried out within the linear micropolar elasticity frameworks. The mathematical model of the linear (or even nonlinear) micropolar elasticity is also expanded to a field theory model by <span class="hlt">variational</span> least action integral and the least action principle. The governing coupled vector differential equations of the linear micropolar elasticity are given. The translational displacements and microrotations in the harmonic coupled <span class="hlt">wave</span> are decomposed into potential and vortex parts. Calibrating equations providing simplification of the equations for the <span class="hlt">wave</span> potentials are proposed. The coupled differential equations are then reduced to uncoupled ones and finally to the Helmholtz <span class="hlt">wave</span> equations. The <span class="hlt">wave</span> equations solutions for the translational and microrotational <span class="hlt">waves</span> potentials are obtained for a high-frequency range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017QS%26T....2c4015O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017QS%26T....2c4015O"><span>Spectral tunability of two-photon states generated by spontaneous four-<span class="hlt">wave</span> mixing: fibre tapering, temperature <span class="hlt">variation</span> and longitudinal stress</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ortiz-Ricardo, E.; Bertoni-Ocampo, C.; Ibarra-Borja, Z.; Ramirez-Alarcon, R.; Cruz-Delgado, D.; Cruz-Ramirez, H.; Garay-Palmett, K.; U'Ren, A. B.</p> <p>2017-09-01</p> <p>We explore three different mechanisms designed to controllably tune the joint spectrum of photon pairs produced by the spontaneous four-<span class="hlt">wave</span> mixing (SFWM) process in optical fibres. The first of these is fibre tapering, which exploits the modified optical dispersion resulting from reducing the core radius. We have presented a theory of SFWM for tapered fibres, as well as experimental results for the SFWM coincidence spectra as a function of the reduction in core radius due to tapering. The other two techniques that we have explored are temperature <span class="hlt">variation</span> and application of longitudinal stress. While the maximum spectral shift observed with these two techniques is smaller than for fibre tapering, they are considerably simpler to implement and have the important advantage that they are based on the use of a single, suitably controlled, fibre specimen.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22093507-rank-restriction-variational-calculation-two-electron-reduced-density-matrices-many-electron-atoms-molecules','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22093507-rank-restriction-variational-calculation-two-electron-reduced-density-matrices-many-electron-atoms-molecules"><span>Rank restriction for the <span class="hlt">variational</span> calculation of two-electron reduced density matrices of many-electron atoms and molecules</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Naftchi-Ardebili, Kasra; Hau, Nathania W.; Mazziotti, David A.</p> <p>2011-11-15</p> <p><span class="hlt">Variational</span> minimization of the ground-state energy as a function of the two-electron reduced density matrix (2-RDM), constrained by necessary N-representability conditions, provides a polynomial-scaling approach to studying strongly correlated molecules without computing the many-electron <span class="hlt">wave</span> function. Here we introduce a route to enhancing necessary conditions for N representability through rank restriction of the 2-RDM. Rather than adding computationally more expensive N-representability conditions, we directly enhance the accuracy of two-particle (2-positivity) conditions through rank restriction, which removes degrees of freedom in the 2-RDM that are not sufficiently constrained. We select the rank of the particle-hole 2-RDM by deriving the ranks associatedmore » with model <span class="hlt">wave</span> functions, including both mean-field and antisymmetrized geminal power (AGP) <span class="hlt">wave</span> functions. Because the 2-positivity conditions are exact for quantum systems with AGP ground states, the rank of the particle-hole 2-RDM from the AGP ansatz provides a minimum for its value in <span class="hlt">variational</span> 2-RDM calculations of general quantum systems. To implement the rank-restricted conditions, we extend a first-order algorithm for large-scale semidefinite programming. The rank-restricted conditions significantly improve the accuracy of the energies; for example, the percentages of correlation energies recovered for HF, CO, and N{sub 2} improve from 115.2%, 121.7%, and 121.5% without rank restriction to 97.8%, 101.1%, and 100.0% with rank restriction. Similar results are found at both equilibrium and nonequilibrium geometries. While more <span class="hlt">accurate</span>, the rank-restricted N-representability conditions are less expensive computationally than the full-rank conditions.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.1761P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.1761P"><span>Role of beach morphology in <span class="hlt">wave</span> overtopping hazard assessment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Phillips, Benjamin; Brown, Jennifer; Bidlot, Jean-Raymond; Plater, Andrew</p> <p>2017-04-01</p> <p>Understanding the role of beach morphology in controlling <span class="hlt">wave</span> overtopping volume will further minimise uncertainties in flood risk assessments at coastal locations defended by engineered structures worldwide. XBeach is used to model <span class="hlt">wave</span> overtopping volume for a 1:200 yr joint probability distribution of <span class="hlt">waves</span> and water levels with measured, pre- and post-storm beach profiles. The simulation with measured bathymetry is repeated with and without morphological evolution enabled during the modelled storm event. This research assesses the role of morphology in controlling <span class="hlt">wave</span> overtopping volumes for hazardous events that meet the typical design level of coastal defence structures. Results show disabling storm-driven morphology under-represents modelled <span class="hlt">wave</span> overtopping volumes by up to 39% under high Hs conditions, and has a greater impact on the <span class="hlt">wave</span> overtopping rate than the variability applied within the boundary conditions due to the range of <span class="hlt">wave</span>-water level combinations that meet the 1:200 yr joint probability criterion. Accounting for morphology in flood modelling is therefore critical for <span class="hlt">accurately</span> predicting <span class="hlt">wave</span> overtopping volumes and the resulting flood hazard and to assess economic losses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhDT.......141S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhDT.......141S"><span>Breaking <span class="hlt">Waves</span> on the Ocean Surface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schwendeman, Michael S.</p> <p></p> <p>In the open ocean, breaking <span class="hlt">waves</span> are a critical mechanism for the transfer of energy, momentum, and mass between the atmosphere and the ocean. Despite much study, fundamental questions about <span class="hlt">wave</span> breaking, such as what determines whether a <span class="hlt">wave</span> will break, remain unresolved. Measurements of oceanic breakers, or "whitecaps," are often used to validate the hypotheses derived in simplified theoretical, numerical, or experimental studies. Real-world measurements are also used to improve the parameterizations of <span class="hlt">wave</span>-breaking in large global models, such as those forecasting climate change. Here, measurements of whitecaps are presented using ship-based cameras, from two experiments in the North Pacific Ocean. First, a method for georectifying the camera imagery is described using the distant horizon, without additional instrumentation. Over the course of the experiment, this algorithm correctly identifies the horizon in 92% of images in which it is visible. In such cases, the calculation of camera pitch and roll is <span class="hlt">accurate</span> to within 1 degree. The main sources of error in the final georectification are from mislabeled horizons due to clouds, rain, or poor lighting, and from vertical "heave" motions of the camera, which cannot be calculated with the horizon method. This method is used for correcting the imagery from the first experiment, and synchronizing the imagery from the second experiment to an onboard inertial motion package. Next, measurements of the whitecap coverage, W, are shown from both experiments. Although W is often used in models to represent whitecapping, large uncertainty remains in the existing parameterizations. The data show good agreement with recent measurements using the wind speed. Although <span class="hlt">wave</span> steepness and dissipation are hypothesized to be more robust predictors of W, this is shown to not always be the case. <span class="hlt">Wave</span> steepness shows comparable success to the wind parameterizations only when using a mean-square slope variable calculated over the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JCoPh.346..572O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JCoPh.346..572O"><span>Energy stable and high-order-<span class="hlt">accurate</span> finite difference methods on staggered grids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>O'Reilly, Ossian; Lundquist, Tomas; Dunham, Eric M.; Nordström, Jan</p> <p>2017-10-01</p> <p>For <span class="hlt">wave</span> propagation over distances of many wavelengths, high-order finite difference methods on staggered grids are widely used due to their excellent dispersion properties. However, the enforcement of boundary conditions in a stable manner and treatment of interface problems with discontinuous coefficients usually pose many challenges. In this work, we construct a provably stable and high-order-<span class="hlt">accurate</span> finite difference method on staggered grids that can be applied to a broad class of boundary and interface problems. The staggered grid difference operators are in summation-by-parts form and when combined with a weak enforcement of the boundary conditions, lead to an energy stable method on multiblock grids. The general applicability of the method is demonstrated by simulating an explosive acoustic source, generating <span class="hlt">waves</span> reflecting against a free surface and material discontinuity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007PhDT........68Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007PhDT........68Z"><span>The development of efficient numerical time-domain modeling methods for geophysical <span class="hlt">wave</span> propagation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhu, Lieyuan</p> <p></p> <p>This Ph.D. dissertation focuses on the numerical simulation of geophysical <span class="hlt">wave</span> propagation in the time domain including elastic <span class="hlt">waves</span> in solid media, the acoustic <span class="hlt">waves</span> in fluid media, and the electromagnetic <span class="hlt">waves</span> in dielectric media. This thesis shows that a linear system model can describe <span class="hlt">accurately</span> the physical processes of those geophysical <span class="hlt">waves</span>' propagation and can be used as a sound basis for modeling geophysical <span class="hlt">wave</span> propagation phenomena. The generalized stability condition for numerical modeling of <span class="hlt">wave</span> propagation is therefore discussed in the context of linear system theory. The efficiency of a series of different numerical algorithms in the time-domain for modeling geophysical <span class="hlt">wave</span> propagation are discussed and compared. These algorithms include the finite-difference time-domain method, pseudospectral time domain method, alternating directional implicit (ADI) finite-difference time domain method. The advantages and disadvantages of these numerical methods are discussed and the specific stability condition for each modeling scheme is carefully derived in the context of the linear system theory. Based on the review and discussion of these existing approaches, the split step, ADI pseudospectral time domain (SS-ADI-PSTD) method is developed and tested for several cases. Moreover, the state-of-the-art stretched-coordinate perfect matched layer (SCPML) has also been implemented in SS-ADI-PSTD algorithm as the absorbing boundary condition for truncating the computational domain and absorbing the artificial reflection from the domain boundaries. After algorithmic development, a few case studies serve as the real-world examples to verify the capacities of the numerical algorithms and understand the capabilities and limitations of geophysical methods for detection of subsurface contamination. The first case is a study using ground penetrating radar (GPR) amplitude <span class="hlt">variation</span> with offset (AVO) for subsurface non-aqueous-liquid (NAPL) contamination. The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014APS..DFDR22010D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014APS..DFDR22010D"><span>Can numerical simulations <span class="hlt">accurately</span> predict hydrodynamic instabilities in liquid films?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Denner, Fabian; Charogiannis, Alexandros; Pradas, Marc; van Wachem, Berend G. M.; Markides, Christos N.; Kalliadasis, Serafim</p> <p>2014-11-01</p> <p>Understanding the dynamics of hydrodynamic instabilities in liquid film flows is an active field of research in fluid dynamics and non-linear science in general. Numerical simulations offer a powerful tool to study hydrodynamic instabilities in film flows and can provide deep insights into the underlying physical phenomena. However, the direct comparison of numerical results and experimental results is often hampered by several reasons. For instance, in numerical simulations the interface representation is problematic and the governing equations and boundary conditions may be oversimplified, whereas in experiments it is often difficult to extract <span class="hlt">accurate</span> information on the fluid and its behavior, e.g. determine the fluid properties when the liquid contains particles for PIV measurements. In this contribution we present the latest results of our on-going, extensive study on hydrodynamic instabilities in liquid film flows, which includes direct numerical simulations, low-dimensional modelling as well as experiments. The major focus is on <span class="hlt">wave</span> regimes, <span class="hlt">wave</span> height and <span class="hlt">wave</span> celerity as a function of Reynolds number and forcing frequency of a falling liquid film. Specific attention is paid to the differences in numerical and experimental results and the reasons for these differences. The authors are grateful to the EPSRC for their financial support (Grant EP/K008595/1).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1989PhDT........97F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1989PhDT........97F"><span>Thermal and Compositional <span class="hlt">Variation</span> of Glassy Metal Structure Factors.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>From, Milton</p> <p></p> <p>The x-ray total structure factor of the glassy -metal alloys Mg_{70}Zn_ {30}, Ca_{70}Mg_{30 } and Mg_{85.5}Cu _{14.5} has been measured at three temperatures: 9K, 150K, and 300K. The data have a statistical precision of about.8% and an absolute accuracy of roughly 3%. Percus-Yevick hard sphere structure factors may be fitted quite <span class="hlt">accurately</span> to the data in the region of the first peak. In addition, the <span class="hlt">variation</span> of the experimental structure factor with composition is found to be consistent with the Percus-Yevick theory. At low k values, Percus -Yevick and other theoretical model structure factors are in poor agreement with the data. Within experimental error, the temperature dependence of the structure factors is in agreement with the Debye plane <span class="hlt">wave</span> phonon model of atomic vibrations. The measured structure factors are used to calculate the electrical resistivity from the Faber-Ziman equation. In most cases, the calculations yield both the correct magnitude of resistivity and sign of the temperature coefficient of resistivity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JGRA..115.7207T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JGRA..115.7207T"><span>Solar cycle <span class="hlt">variation</span> of geosynchronous plasma mass density derived from the frequency of standing Alfvén <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Takahashi, Kazue; Denton, Richard E.; Singer, Howard J.</p> <p>2010-07-01</p> <p>We have studied the solar cycle <span class="hlt">variation</span> of equatorial plasma mass density ρeq in the plasma trough at geosynchronous altitude. The density was indirectly determined from the frequency, fT3, of the third harmonic of toroidal standing Alfvén <span class="hlt">waves</span> detected over a 12 year period from 1980 to 1991 with magnetometers on five Geostationary Operational Environmental Satellites (GOES). Realistic models of the ambient magnetic field and field line mass distribution were used in numerically solving the <span class="hlt">wave</span> equation to relate fT3 to ρeq. Scanning the magnetometer data in a 30 min time window that moved forward in 10 min steps, we obtained 228,382 fT3 samples equivalent to 1586 days of data. The detection rate of fT3 is highest (˜50%) in the prenoon sector, and fT3 and ρeq samples from this sector were used to examine their dependence on F10.7, Kp, and Dst. Overall, F10.7 exhibits the highest correlation with fT3 and ρeq, implying that the solar UV/EUV control of ion production at the ionospheric height is strongly reflected in mass density <span class="hlt">variations</span> at geosynchronous orbit. Using 27 day medians computed excluding periods of plasmasphere expansion to geosynchronous orbit and geomagnetic storm, we obtained the empirical formula fT3 (mHz) = 38 - 0.097F10.7 and logρeq (amu cm-3) = 0.42 + 0.0039F10.7, where F10.7 is given in the solar flux units 10-22 W · m-2 · Hz-1. This last formula means that with the 27 day F10.7 in the range of 68-255 in the selected solar cycle, the mass density varied by a factor of ˜5 from ˜5 to ˜26 amu cm-3. During extremely quiet times (Kp averaged using a 3 day time scale <1), for which the plasmasphere may extend out to geosynchronous orbit, and during storm periods (Dst < -50 nT), the mass density may be enhanced beyond these values.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3722521','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3722521"><span>Automated design of paralogue ratio test assays for the <span class="hlt">accurate</span> and rapid typing of copy number <span class="hlt">variation</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Veal, Colin D.; Xu, Hang; Reekie, Katherine; Free, Robert; Hardwick, Robert J.; McVey, David; Brookes, Anthony J.; Hollox, Edward J.; Talbot, Christopher J.</p> <p>2013-01-01</p> <p>Motivation: Genomic copy number <span class="hlt">variation</span> (CNV) can influence susceptibility to common diseases. High-throughput measurement of gene copy number on large numbers of samples is a challenging, yet critical, stage in confirming observations from sequencing or array Comparative Genome Hybridization (CGH). The paralogue ratio test (PRT) is a simple, cost-effective method of <span class="hlt">accurately</span> determining copy number by quantifying the amplification ratio between a target and reference amplicon. PRT has been successfully applied to several studies analyzing common CNV. However, its use has not been widespread because of difficulties in assay design. Results: We present PRTPrimer (www.prtprimer.org) software for automated PRT assay design. In addition to stand-alone software, the web site includes a database of pre-designed assays for the human genome at an average spacing of 6 kb and a web interface for custom assay design. Other reference genomes can also be analyzed through local installation of the software. The usefulness of PRTPrimer was tested within known CNV, and showed reproducible quantification. This software and database provide assays that can rapidly genotype CNV, cost-effectively, on a large number of samples and will enable the widespread adoption of PRT. Availability: PRTPrimer is available in two forms: a Perl script (version 5.14 and higher) that can be run from the command line on Linux systems and as a service on the PRTPrimer web site (www.prtprimer.org). Contact: cjt14@le.ac.uk Supplementary Information: Supplementary data are available at Bioinformatics online. PMID:23742985</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11.4343Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.4343Y"><span>Development of Operational <span class="hlt">Wave</span>-Tide-Storm surges Coupling Prediction System</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>You, S. H.; Park, S. W.; Kim, J. S.; Kim, K. L.</p> <p>2009-04-01</p> <p>The Korean Peninsula is surrounded by the Yellow Sea, East China Sea, and East Sea. This complex oceanographic system includes large tides in the Yellow Sea and seasonally varying monsoon and typhoon events. For Korea's coastal regions, floods caused by <span class="hlt">wave</span> and storm surges are among the most serious threats. To predict more <span class="hlt">accurate</span> <span class="hlt">wave</span> and storm surges, the development of coupling <span class="hlt">wave</span>-tide-storm surges prediction system is essential. For the time being, <span class="hlt">wave</span> and storm surges predictions are still made separately in KMA (Korea Meteorological Administration) and most operational institute. However, many researchers have emphasized the effects of tides and storm surges on wind <span class="hlt">waves</span> and recommended further investigations into the effects of <span class="hlt">wave</span>-tide-storm surges interactions and coupling module. In Korea, especially, tidal height and current give a great effect on the <span class="hlt">wave</span> prediction in the Yellow sea where is very high tide and related research is not enough. At present, KMA has operated the <span class="hlt">wave</span> (RWAM : Regional <span class="hlt">Wave</span> Model) and storm surges/tide prediction system (STORM : Storm Surges/Tide Operational Model) for ocean forecasting. The RWAM is WAVEWATCH III which is a third generation <span class="hlt">wave</span> model developed by Tolman (1989). The STORM is based on POM (Princeton Ocean Model, Blumberg and Mellor, 1987). The RWAM and STORM cover the northwestern Pacific Ocean from 115°E to 150°E and from 20°N to 52°N. The horizontal grid intervals are 1/12° in both latitudinal and longitudinal directions. These two operational models are coupled to simulate <span class="hlt">wave</span> heights for typhoon case. The sea level and current simulated by storm surge model are used for the input of <span class="hlt">wave</span> model with 3 hour interval. The coupling simulation between <span class="hlt">wave</span> and storm surge model carried out for Typhoon Nabi (0514), Shanshan(0613) and Nari (0711) which were effected on Korea directly. We simulated significant <span class="hlt">wave</span> height simulated by <span class="hlt">wave</span> model and coupling model and compared difference between</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70032812','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70032812"><span>Rayleigh-<span class="hlt">wave</span> dispersive energy imaging and mode separating by high-resolution linear Radon transform</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Luo, Y.; Xu, Y.; Liu, Q.; Xia, J.</p> <p>2008-01-01</p> <p>In recent years, multichannel analysis of surface <span class="hlt">waves</span> (MASW) has been increasingly used for obtaining vertical shear-<span class="hlt">wave</span> velocity profiles within near-surface materials. MASW uses a multichannel recording approach to capture the time-variant, full-seismic wavefield where dispersive surface <span class="hlt">waves</span> can be used to estimate near-surface S-<span class="hlt">wave</span> velocity. The technique consists of (1) acquisition of broadband, high-frequency ground roll using a multichannel recording system; (2) efficient and <span class="hlt">accurate</span> algorithms that allow the extraction and analysis of 1D Rayleigh-<span class="hlt">wave</span> dispersion curves; (3) stable and efficient inversion algorithms for estimating S-<span class="hlt">wave</span> velocity profiles; and (4) construction of the 2D S-<span class="hlt">wave</span> velocity field map.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPhCS.744a2055M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPhCS.744a2055M"><span>Remote pipeline assessment and condition monitoring using low-frequency axisymmetric <span class="hlt">waves</span>: a theoretical study of torsional <span class="hlt">wave</span> motion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Muggleton, J. M.; Rustighi, E.; Gao, Y.</p> <p>2016-09-01</p> <p><span class="hlt">Waves</span> that propagate at low frequencies in buried pipes are of considerable interest in a variety of practical scenarios, for example leak detection, remote pipe detection, and pipeline condition assessment and monitoring. Particularly useful are the n = 0, or axisymmetric, modes in which there is no displacement (or pressure) <span class="hlt">variation</span> over the pipe cross section. Previous work has focused on two of the three axisymmetric wavetypes that can propagate: the s = 1, fluid- dominated <span class="hlt">wave</span>; and the s = 2, shell-dominated <span class="hlt">wave</span>. In this paper, the third axisymmetric wavetype, the s = 0 torsional <span class="hlt">wave</span>, is studied. Whilst there is a large body of research devoted to the study of torsional <span class="hlt">waves</span> and their use for defect detection in pipes at ultrasonic frequencies, little is known about their behaviour and possible exploitation at lower frequencies. Here, a low- frequency analytical dispersion relationship is derived for the torsional wavenumber for a buried pipe from which both the wavespeed and <span class="hlt">wave</span> attenuation can be obtained. How the torsional <span class="hlt">waves</span> subsequently radiate to the ground surface is then investigated, with analytical expressions being presented for the ground surface displacement above the pipe resulting from torsional <span class="hlt">wave</span> motion within the pipe wall. Example results are presented and, finally, how such <span class="hlt">waves</span> might be exploited in practice is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19730045264&hterms=Aorta&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DAorta','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19730045264&hterms=Aorta&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DAorta"><span>Influence of flow and pressure on <span class="hlt">wave</span> propagation in the canine aorta.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Histand, M. B.; Anliker, M.</p> <p>1973-01-01</p> <p>Data on <span class="hlt">wave</span> speed acquired from 20 anesthetized dogs showed that the thoracic aorta was essentially nondispersive for small artificially generated pressure <span class="hlt">waves</span> traveling in the downstream or the upstream direction and having frequencies between 40 and 120 Hz. The amplitude of these <span class="hlt">waves</span> decayed exponentially with the distance traveled. Theoretical studies are cited which have shown that changes in <span class="hlt">wave</span> speed due to <span class="hlt">variations</span> in pressure and flow produce marked nonlinear effects in hemodynamics.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19900009611','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19900009611"><span>Asymptotic boundary conditions for dissipative <span class="hlt">waves</span>: General theory</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hagstrom, Thomas</p> <p>1990-01-01</p> <p>An outstanding issue in the computational analysis of time dependent problems is the imposition of appropriate radiation boundary conditions at artificial boundaries. <span class="hlt">Accurate</span> conditions are developed which are based on the asymptotic analysis of <span class="hlt">wave</span> propagation over long ranges. Employing the method of steepest descents, dominant <span class="hlt">wave</span> groups are identified and simple approximations to the dispersion relation are considered in order to derive local boundary operators. The existence of a small number of dominant <span class="hlt">wave</span> groups may be expected for systems with dissipation. Estimates of the error as a function of domain size are derived under general hypotheses, leading to convergence results. Some practical aspects of the numerical construction of the asymptotic boundary operators are also discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25235007','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25235007"><span>Time-domain separation of interfering <span class="hlt">waves</span> in cancellous bone using bandlimited deconvolution: simulation and phantom study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wear, Keith A</p> <p>2014-04-01</p> <p>In through-transmission interrogation of cancellous bone, two longitudinal pulses ("fast" and "slow" <span class="hlt">waves</span>) may be generated. Fast and slow <span class="hlt">wave</span> properties convey information about material and micro-architectural characteristics of bone. However, these properties can be difficult to assess when fast and slow <span class="hlt">wave</span> pulses overlap in time and frequency domains. In this paper, two methods are applied to decompose signals into fast and slow <span class="hlt">waves</span>: bandlimited deconvolution and modified least-squares Prony's method with curve-fitting (MLSP + CF). The methods were tested in plastic and Zerdine(®) samples that provided fast and slow <span class="hlt">wave</span> velocities commensurate with velocities for cancellous bone. Phase velocity estimates were <span class="hlt">accurate</span> to within 6 m/s (0.4%) (slow <span class="hlt">wave</span> with both methods and fast <span class="hlt">wave</span> with MLSP + CF) and 26 m/s (1.2%) (fast <span class="hlt">wave</span> with bandlimited deconvolution). Midband signal loss estimates were <span class="hlt">accurate</span> to within 0.2 dB (1.7%) (fast <span class="hlt">wave</span> with both methods), and 1.0 dB (3.7%) (slow <span class="hlt">wave</span> with both methods). Similar accuracies were found for simulations based on fast and slow <span class="hlt">wave</span> parameter values published for cancellous bone. These methods provide sufficient accuracy and precision for many applications in cancellous bone such that experimental error is likely to be a greater limiting factor than estimation error.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160005999','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160005999"><span>Detection of CFRP Composite Manufacturing Defects Using a Guided <span class="hlt">Wave</span> Approach</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hudson, Tyler B.; Hou, Tan-Hung; Grimsley, Brian W.; Yuan, Fuh-Gwo</p> <p>2015-01-01</p> <p>NASA Langley Research Center is investigating a guided-<span class="hlt">wave</span> based defect detection technique for as-fabricated carbon fiber reinforced polymer (CFRP) composites. This technique will be extended to perform in-process cure monitoring, defect detection and size determination, and ultimately a closed-loop process control to maximize composite part quality and consistency. The overall objective of this work is to determine the capability and limitations of the proposed defect detection technique, as well as the number and types of sensors needed to identify the size, type, and location of the predominant types of manufacturing defects associated with laminate layup and cure. This includes, porosity, gaps, overlaps, through-the-thickness fiber waviness, and in-plane fiber waviness. The present study focuses on detection of the porosity formed from <span class="hlt">variations</span> in the matrix curing process, and on local overlaps intentionally introduced during layup of the prepreg. By terminating the cycle prematurely, three 24-ply unidirectional composite panels were manufactured such that each subsequent panel had a higher final degree of cure, and lower level of porosity. It was demonstrated that the group velocity, normal to the fiber direction, of a guided <span class="hlt">wave</span> mode increased by 5.52 percent from the first panel to the second panel and 1.26 percent from the second panel to the third panel. Therefore, group velocity was utilized as a metric for degree of cure and porosity measurements. A fully non-contact guided <span class="hlt">wave</span> hybrid system composed of an air-coupled transducer and a laser Doppler vibrometer (LDV) was used for the detection and size determination of an overlap By transforming the plate response from the time-space domain to the frequency-wavenumber domain, the total wavefield was then separated into the incident and backscatter <span class="hlt">waves</span>. The overlap region was <span class="hlt">accurately</span> imaged by using a zero-lag cross-correlation (ZLCC) imaging condition, implying the incident and backscattered</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950004077','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950004077"><span>Ferruleless coupled-cavity traveling-<span class="hlt">wave</span> tube cold-test characteristics simulated with micro-SOS</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schroeder, Dana L.; Wilson, Jeffrey D.</p> <p>1993-01-01</p> <p>The three-dimensional, electromagnetic circuit analysis code, Micro-SOS, can be used to reduce expensive and time consuming experimental 'cold-testing' of traveling-<span class="hlt">wave</span> tube (TWT) circuits. The frequency-phase dispersion and beam interaction impedance characteristics of a ferruleless coupled-cavity traveling-<span class="hlt">wave</span> tube slow-<span class="hlt">wave</span> circuit were simulated using the code. Computer results agree closely with experimental data. <span class="hlt">Variations</span> in the cavity geometry dimensions of period length and gap-to-period ratio were modeled. These <span class="hlt">variations</span> can be used in velocity taper designs to reduce the radiofrequency (RF) phase velocity in synchronism with the decelerating electron beam. Such circuit designs can result in enhanced TWT power and efficiency.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840003706','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840003706"><span>User's guide for a computer program for calculating the zero-lift <span class="hlt">wave</span> drag of complex aircraft configurations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Craidon, C. B.</p> <p>1983-01-01</p> <p>A computer program was developed to extend the geometry input capabilities of previous versions of a supersonic zero lift <span class="hlt">wave</span> drag computer program. The arbitrary geometry input description is flexible enough to describe almost any complex aircraft concept, so that highly <span class="hlt">accurate</span> <span class="hlt">wave</span> drag analysis can now be performed because complex geometries can be represented <span class="hlt">accurately</span> and do not have to be modified to meet the requirements of a restricted input format.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010019002','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010019002"><span>Signatures of Nonlinear <span class="hlt">Waves</span> in Coronal Plumes and Holes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ofman, Leon</p> <p>1999-01-01</p> <p>In recent Ultraviolet Coronagraph Spectrometer/Solar and Heliospheric Observatory (UVCS/SOHO) White Light Channel (WLC) observations we found quasi-periodic <span class="hlt">variations</span> in the polarized brightness (pB) in the polar coronal holes at heliocentric distances of 1.9-2.45 solar radii. The motivation for the observation is the 2.5D Magnetohydrodynamics (MHD) model of solar wind acceleration by nonlinear <span class="hlt">waves</span>, that predicts compressive fluctuations in coronal holes. To help identify the <span class="hlt">waves</span> observed with the UVCS/WLC we model the propagation and dissipation of slow magnetosonic <span class="hlt">waves</span> in polar plumes using 1D MHD code in spherical geometry, We find that the slow <span class="hlt">waves</span> nonlinearly steepen in the gravitationally stratified plumes. The nonlinear steepening of the <span class="hlt">waves</span> leads to enhanced dissipation due to compressive viscosity at the <span class="hlt">wave</span>-fronts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920041688&hterms=environnement&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Denvironnement','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920041688&hterms=environnement&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Denvironnement"><span>The Unified Radio and Plasma <span class="hlt">wave</span> investigation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stone, R. G.; Bougeret, J. L.; Caldwell, J.; Canu, P.; De Conchy, Y.; Cornilleau-Wehrlin, N.; Desch, M. D.; Fainberg, J.; Goetz, K.; Goldstein, M. L.</p> <p>1992-01-01</p> <p>The scientific objectives of the Ulysses Unified Radio and Plasma <span class="hlt">wave</span> (URAP) experiment are twofold: (1) the determination of the direction, angular size, and polarization of radio sources for remote sensing of the heliosphere and the Jovian magnetosphere and (2) the detailed study of local <span class="hlt">wave</span> phenomena, which determine the transport coefficients of the ambient plasma. A brief discussion of the scientific goals of the experiment is followed by a comprehensive description of the instrument. The URAP sensors consist of a 72.5 m electric field antenna in the spin plane, a 7.5-m electric field monopole along the spin axis of a pair of orthogonal search coil magnetic antennas. The various receivers, designed to encompass specific needs of the investigation, cover the frequency range from dc to 1 MHz. A relaxation sounder provides very <span class="hlt">accurate</span> electron density measurements. Radio and plasma <span class="hlt">wave</span> observations are shown to demonstrate the capabilities and limitations of the URAP instruments: radio observations include solar bursts, auroral kilometric radiation, and Jovian bursts; plasma <span class="hlt">waves</span> include Langmuir <span class="hlt">waves</span>, ion acousticlike noise, and whistlers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002IJAEO...4..147M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002IJAEO...4..147M"><span>Azimuth cut-off model for significant <span class="hlt">wave</span> height investigation along coastal water of Kuala Terengganu, Malaysia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marghany, Maged; Ibrahim, Zelina; Van Genderen, Johan</p> <p>2002-11-01</p> <p>The present work is used to operationalize the azimuth cut-off concept in the study of significant <span class="hlt">wave</span> height. Three ERS-1 images have been used along the coastal waters of Terengganu, Malaysia. The quasi-linear transform was applied to map the SAR <span class="hlt">wave</span> spectra into real ocean <span class="hlt">wave</span> spectra. The azimuth cut-off was then used to model the significant <span class="hlt">wave</span> height. The results show that azimuth cut-off varied with the different period of the ERS-1 images. This is because of the fact that the azimuth cut-off is a function of wind speed and significant <span class="hlt">wave</span> height. It is of interest to find that the significant <span class="hlt">wave</span> height modeled from azimuth cut-off is in good relation with ground <span class="hlt">wave</span> conditions. It can be concluded that ERS-1 can be used as a monitoring tool in detecting the significant <span class="hlt">wave</span> height <span class="hlt">variation</span>. The azimuth cut-off can be used to model the significant <span class="hlt">wave</span> height. This means that the quasi-linear transform could be a good application to significant <span class="hlt">wave</span> height <span class="hlt">variation</span> during different seasons.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ClDy...50.2783M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ClDy...50.2783M"><span>Understanding Rossby <span class="hlt">wave</span> trains forced by the Indian Ocean Dipole</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McIntosh, Peter C.; Hendon, Harry H.</p> <p>2018-04-01</p> <p>Convective <span class="hlt">variations</span> over the tropical Indian Ocean associated with ENSO and the Indian Ocean Dipole force a Rossby <span class="hlt">wave</span> train that appears to emanate poleward and eastward to the south of Australia and which causes climate <span class="hlt">variations</span> across southern Australia and more generally throughout the Southern Hemisphere extratropics. However, during austral winter, the subtropical jet that extends from the eastern Indian Ocean into the western Pacific at Australian latitudes should effectively prohibit continuous propagation of a stationary Rossby <span class="hlt">wave</span> from the tropics into the extratropics because the meridional gradient of mean absolute vorticity goes to zero on its poleward flank. The observed <span class="hlt">wave</span> train indeed exhibits strong convergence of <span class="hlt">wave</span> activity flux upon encountering this region of vanishing vorticity gradient and with some indication of reflection back into the tropics, indicating the continuous propagation of the stationary Rossby <span class="hlt">wave</span> train from low to high latitudes is inhibited across the south of Australia. However, another Rossby <span class="hlt">wave</span> train appears to emanate upstream of Australia on the poleward side of the subtropical jet and propagates eastward along the waveguide of the eddy-driven (sub-polar) jet into the Pacific sector of the Southern Ocean. This combination of evanescent <span class="hlt">wave</span> train from the tropics and eastward propagating <span class="hlt">wave</span> train emanating from higher latitudes upstream of Australia gives the appearance of a continuous Rossby <span class="hlt">wave</span> train propagating from the tropical Indian Ocean into higher southern latitudes. The extratropical Rossby <span class="hlt">wave</span> source on the poleward side of the subtropical jet stems from induced changes in transient eddy activity in the main storm track of the Southern Hemisphere. During austral spring, when the subtropical jet weakens, the Rossby <span class="hlt">wave</span> train emanating from Indian Ocean convection is explained more traditionally by direct dispersion from divergence forcing at low latitudes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DFDM20004D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFDM20004D"><span>Transition of torque pattern in undulatory locomotion due to <span class="hlt">wave</span> number <span class="hlt">variation</span> in resistive force dominated media</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ding, Yang; Ming, Tingyu</p> <p>2016-11-01</p> <p>In undulatory locomotion, torque (bending moment) is required along the body to overcome the external forces from environments and bend the body. Previous observations on animals using less than two wavelengths on the body showed such torque has a single traveling <span class="hlt">wave</span> pattern. Using resistive force theory model and considering the torque generated by external force in a resistive force dominated media, we found that as the <span class="hlt">wave</span> number (number of wavelengths on the locomotor's body) increases from 0.5 to 1.8, the speed of the traveling <span class="hlt">wave</span> of torque decreases. When the <span class="hlt">wave</span> number increases to 2 and greater, the torque pattern transits from a single traveling <span class="hlt">wave</span> to a two traveling <span class="hlt">waves</span> and then a complex pattern that consists two <span class="hlt">wave</span>-like patterns. By analyzing the force distribution and its contribution to the torque, we explain the speed decrease of the torque <span class="hlt">wave</span> and the pattern transition. This research is partially supported by the Recruitment Program of Global Young Experts (China).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMMR24B..06M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMMR24B..06M"><span><span class="hlt">Variations</span> in Temperature at the Base of the Lithosphere Beneath the Archean Superior Province, Canada</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mareschal, J.; Jaupart, C. P.</p> <p>2013-12-01</p> <p>Most of the <span class="hlt">variations</span> in surface heat flux in stable continents are caused by <span class="hlt">variations</span> in crustal heat production, with an almost uniform heat flux at the base of the crust ( 15+/-3 mW/m2). Such relatively small differences in Moho heat flux cannot be resolved by heat flow data alone, but they lead to important lateral <span class="hlt">variations</span> in lithospheric temperatures and thicknesses. In order to better constrain temperatures in the lower lithosphere, we have combined surface heat flow and heat production data from the southern Superior Province in Canada with vertical shear <span class="hlt">wave</span> velocity profiles obtained from surface <span class="hlt">wave</span> inversion. We use the Monte-Carlo method to generate lithospheric temperature profiles from which shear <span class="hlt">wave</span> velocity can be calculated for a given mantle composition. We eliminate thermal models which yield lithospheric and sub-lithospheric velocities that do not fit the shear <span class="hlt">wave</span> velocity profile. Surface heat flux being constrained, the free parameters of the thermal model are: the mantle heat flux, the mantle heat production, the crustal differentiation index (ratio of surface to bulk crustal heat production) and the temperature of the mantle isentrope. Two conclusions emerge from this study. One is that, for some profiles, the vertical <span class="hlt">variations</span> in shear <span class="hlt">wave</span> velocities cannot be accounted for by temperature alone but also require compositional changes within the lithosphere. The second is that there are long wavelength horizontal <span class="hlt">variations</span> in mantle temperatures (~80-100K) at the base of the lithosphere and in the mantle below</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28214750','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28214750"><span>Propagation of thickness shear <span class="hlt">waves</span> in a periodically corrugated quartz crystal plate and its application exploration in acoustic <span class="hlt">wave</span> filters.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Peng; Cheng, Li</p> <p>2017-05-01</p> <p>The propagation of thickness shear <span class="hlt">waves</span> in a periodically corrugated quartz crystal plate is investigated in the present paper using a power series expansion technique. In the proposed simulation model, an equivalent continuity of shear stress moment is introduced as an approximation to handle sectional interfaces with abrupt thickness changes. The Bloch theory is applied to simulate the band structures for three different thickness <span class="hlt">variation</span> patterns. It is shown that the power series expansion method exhibits good convergence and accuracy, in agreement with results by finite element method (FEM). A broad stop band can be obtained in the power transmission spectra owing to the trapped thickness shear modes excited by the thickness <span class="hlt">variation</span>, whose physical mechanism is totally different from the well-known Bragg scattering effect and is insensitive to the structural periodicity. Based on the observed energy trapping phenomenon, an acoustic <span class="hlt">wave</span> filter is proposed in a quartz plate with sectional decreasing thickness, which inhibits <span class="hlt">wave</span> propagation in different regions. Copyright © 2017 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17771283','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17771283"><span>Voyager 2 plasma <span class="hlt">wave</span> observations at saturn.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Scarf, F L; Gurnett, D A; Kurth, W S; Poynter, R L</p> <p>1982-01-29</p> <p>The first inbound Voyager 2 crossing of Saturn's bow shock [at 31.7 Saturn radii (RS), near local noon] and the last outbound crossing (at 87.4 RS, near local dawn) had similar plasma <span class="hlt">wave</span> signatures. However, many other aspects of the plasma <span class="hlt">wave</span> measurements differed considerably during the inbound and outbound passes, suggesting the presence of effects associated with significant north-south or noon-dawn asymmetries, or temporal <span class="hlt">variations</span>. Within Saturn's magnetosphere, the plasma <span class="hlt">wave</span> instrument detected electron plasma oscillations, upper hybrid resonance emissions, half-gyrofrequency harmonics, hiss and chorus, narrowband electromagnetic emissions and broadband Saturn radio noise, and noise bursts with characteristics of static. At the ring plane crossing, the plasma <span class="hlt">wave</span> instrument also detected a large number of intense impulses that we interpret in terms of ring particle impacts on Voyager 2.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoJI.211.1640J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoJI.211.1640J"><span>Linking source region and ocean <span class="hlt">wave</span> parameters with the observed primary microseismic noise</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Juretzek, C.; Hadziioannou, C.</p> <p>2017-12-01</p> <p>In previous studies, the contribution of Love <span class="hlt">waves</span> to the primary microseismic noise field was found to be comparable to those of Rayleigh <span class="hlt">waves</span>. However, so far only few studies analysed both <span class="hlt">wave</span> types present in this microseismic noise band, which is known to be generated in shallow water and the theoretical understanding has mainly evolved for Rayleigh <span class="hlt">waves</span> only. Here, we study the relevance of different source region parameters on the observed primary microseismic noise levels of Love and Rayleigh <span class="hlt">waves</span> simultaneously. By means of beamforming and correlation of seismic noise amplitudes with ocean <span class="hlt">wave</span> heights in the period band between 12 and 15 s, we analysed how source areas of both <span class="hlt">wave</span> types compare with each other around Europe. The generation effectivity in different source regions was compared to ocean <span class="hlt">wave</span> heights, peak ocean gravity <span class="hlt">wave</span> propagation direction and bathymetry. Observed Love <span class="hlt">wave</span> noise amplitudes correlate comparably well with near coastal ocean <span class="hlt">wave</span> parameters as Rayleigh <span class="hlt">waves</span>. Some coastal regions serve as especially effective sources for one or the other <span class="hlt">wave</span> type. These coincide not only with locations of high <span class="hlt">wave</span> heights but also with complex bathymetry. Further, Rayleigh and Love <span class="hlt">wave</span> noise amplitudes seem to depend equally on the local ocean <span class="hlt">wave</span> heights, which is an indication for a coupled <span class="hlt">variation</span> with swell height during the generation of both <span class="hlt">wave</span> types. However, the <span class="hlt">wave</span>-type ratio varies directionally. This observation likely hints towards a spatially varying importance of different source mechanisms or structural influences. Further, the <span class="hlt">wave</span>-type ratio is modulated depending on peak ocean <span class="hlt">wave</span> propagation directions which could indicate a <span class="hlt">variation</span> of different source mechanism strengths but also hints towards an imprint of an effective source radiation pattern. This emphasizes that the inclusion of both <span class="hlt">wave</span> types may provide more constraints for the understanding of acting generation mechanisms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JPhCS1007a2011M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JPhCS1007a2011M"><span><span class="hlt">Variational</span> estimate method for solving autonomous ordinary differential equations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mungkasi, Sudi</p> <p>2018-04-01</p> <p>In this paper, we propose a method for solving first-order autonomous ordinary differential equation problems using a <span class="hlt">variational</span> estimate formulation. The <span class="hlt">variational</span> estimate is constructed with a Lagrange multiplier which is chosen optimally, so that the formulation leads to an <span class="hlt">accurate</span> solution to the problem. The <span class="hlt">variational</span> estimate is an integral form, which can be computed using a computer software. As the <span class="hlt">variational</span> estimate is an explicit formula, the solution is easy to compute. This is a great advantage of the <span class="hlt">variational</span> estimate formulation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhLA..382.1120K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhLA..382.1120K"><span><span class="hlt">Variational</span> model for one-dimensional quantum magnets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kudasov, Yu. B.; Kozabaranov, R. V.</p> <p>2018-04-01</p> <p>A new <span class="hlt">variational</span> technique for investigation of the ground state and correlation functions in 1D quantum magnets is proposed. A spin Hamiltonian is reduced to a fermionic representation by the Jordan-Wigner transformation. The ground state is described by a new non-local trial <span class="hlt">wave</span> function, and the total energy is calculated in an analytic form as a function of two <span class="hlt">variational</span> parameters. This approach is demonstrated with an example of the XXZ-chain of spin-1/2 under a staggered magnetic field. Generalizations and applications of the <span class="hlt">variational</span> technique for low-dimensional magnetic systems are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGE....12..435A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGE....12..435A"><span>Finite difference elastic <span class="hlt">wave</span> modeling with an irregular free surface using ADER scheme</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Almuhaidib, Abdulaziz M.; Nafi Toksöz, M.</p> <p>2015-06-01</p> <p>In numerical modeling of seismic <span class="hlt">wave</span> propagation in the earth, we encounter two important issues: the free surface and the topography of the surface (i.e. irregularities). In this study, we develop a 2D finite difference solver for the elastic <span class="hlt">wave</span> equation that combines a 4th- order ADER scheme (Arbitrary high-order accuracy using DERivatives), which is widely used in aeroacoustics, with the characteristic variable method at the free surface boundary. The idea is to treat the free surface boundary explicitly by using ghost values of the solution for points beyond the free surface to impose the physical boundary condition. The method is based on the velocity-stress formulation. The ultimate goal is to develop a numerical solver for the elastic <span class="hlt">wave</span> equation that is stable, <span class="hlt">accurate</span> and computationally efficient. The solver treats smooth arbitrary-shaped boundaries as simple plane boundaries. The computational cost added by treating the topography is negligible compared to flat free surface because only a small number of grid points near the boundary need to be computed. In the presence of topography, using 10 grid points per shortest shear-wavelength, the solver yields <span class="hlt">accurate</span> results. Benchmark numerical tests using several complex models that are solved by our method and other independent <span class="hlt">accurate</span> methods show an excellent agreement, confirming the validity of the method for modeling elastic <span class="hlt">waves</span> with an irregular free surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19740037972&hterms=concept+theory+General+systems&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dconcept%2Btheory%2BGeneral%2Bsystems','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19740037972&hterms=concept+theory+General+systems&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dconcept%2Btheory%2BGeneral%2Bsystems"><span>Conservation of <span class="hlt">wave</span> action. [in discrete oscillating system</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hayes, W. D.</p> <p>1974-01-01</p> <p>It is pointed out that two basic principles appear in the theory of <span class="hlt">wave</span> propagation, including the existence of a phase variable and a law governing the intensity, in terms of a conservation law. The concepts underlying such a conservation law are explored. The <span class="hlt">waves</span> treated are conservative in the sense that they obey equations derivable from a <span class="hlt">variational</span> principle applied to a Lagrangian functional. A discrete oscillating system is considered. The approach employed also permits in a natural way the definition of a local action density and flux in problems in which the <span class="hlt">waves</span> are modal or general.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1369205-simulations-seismic-wave-propagation-mars','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1369205-simulations-seismic-wave-propagation-mars"><span>Simulations of Seismic <span class="hlt">Wave</span> Propagation on Mars</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Bozdağ, Ebru; Ruan, Youyi; Metthez, Nathan; ...</p> <p>2017-03-23</p> <p>In this paper, we present global and regional synthetic seismograms computed for 1D and 3D Mars models based on the spectral-element method. For global simulations, we implemented a radially-symmetric Mars model with a 110 km thick crust. For this 1D model, we successfully benchmarked the 3D seismic <span class="hlt">wave</span> propagation solver SPECFEM3D_GLOBE against the 2D axisymmetric <span class="hlt">wave</span> propagation solver AxiSEM at periods down to 10 s. We also present higher-resolution body-<span class="hlt">wave</span> simulations with AxiSEM down to 1 s in a model with a more complex 1D crust, revealing <span class="hlt">wave</span> propagation effects that would have been difficult to interpret based on raymore » theory. For 3D global simulations based on SPECFEM3D_GLOBE, we superimposed 3D crustal thickness <span class="hlt">variations</span> capturing the distinct crustal dichotomy between Mars’ northern and southern hemispheres, as well as topography, ellipticity, gravity, and rotation. The global simulations clearly indicate that the 3D crust speeds up body <span class="hlt">waves</span> compared to the reference 1D model, whereas it significantly changes surface waveforms and their dispersive character depending on its thickness. We also perform regional simulations with the solver SES3D based on 3D crustal models derived from surface composition, thereby addressing the effects of various distinct crustal features down to 2 s. The regional simulations confirm the strong effects of crustal <span class="hlt">variations</span> on waveforms. Finally, we conclude that the numerical tools are ready for examining more scenarios, including various other seismic models and sources.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1369205','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1369205"><span>Simulations of Seismic <span class="hlt">Wave</span> Propagation on Mars</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Bozdağ, Ebru; Ruan, Youyi; Metthez, Nathan</p> <p></p> <p>In this paper, we present global and regional synthetic seismograms computed for 1D and 3D Mars models based on the spectral-element method. For global simulations, we implemented a radially-symmetric Mars model with a 110 km thick crust. For this 1D model, we successfully benchmarked the 3D seismic <span class="hlt">wave</span> propagation solver SPECFEM3D_GLOBE against the 2D axisymmetric <span class="hlt">wave</span> propagation solver AxiSEM at periods down to 10 s. We also present higher-resolution body-<span class="hlt">wave</span> simulations with AxiSEM down to 1 s in a model with a more complex 1D crust, revealing <span class="hlt">wave</span> propagation effects that would have been difficult to interpret based on raymore » theory. For 3D global simulations based on SPECFEM3D_GLOBE, we superimposed 3D crustal thickness <span class="hlt">variations</span> capturing the distinct crustal dichotomy between Mars’ northern and southern hemispheres, as well as topography, ellipticity, gravity, and rotation. The global simulations clearly indicate that the 3D crust speeds up body <span class="hlt">waves</span> compared to the reference 1D model, whereas it significantly changes surface waveforms and their dispersive character depending on its thickness. We also perform regional simulations with the solver SES3D based on 3D crustal models derived from surface composition, thereby addressing the effects of various distinct crustal features down to 2 s. The regional simulations confirm the strong effects of crustal <span class="hlt">variations</span> on waveforms. Finally, we conclude that the numerical tools are ready for examining more scenarios, including various other seismic models and sources.« less</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA598232','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA598232"><span>Simulation of <span class="hlt">Wave</span> and Current Processes Using Novel, Phase Resolving Models</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2013-09-30</p> <p>fundamental technical approach is to represent nearshore water <span class="hlt">wave</span> systems by retaining Boussinesq scaling assumptions, but without any assumption of... Boussinesq approach that allows for much more freedom in determining the system properties. The resulting systems can have two forms: a classic...of a pressure-Poisson approach to Boussinesq systems . The <span class="hlt">wave</span> generation-absorption system has now been shown to provide highly <span class="hlt">accurate</span> results</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA161539','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA161539"><span>Proceedings of the 1985 ONR/NAVAIR <span class="hlt">Wave</span> Rotor Research and Technology Workshop</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1985-05-01</p> <p>was building the device for a customer realized that design modifications were needed to account for nonsteady flow phenomena. The patent by C. Seippel...location 121.9’-144* Driven outlet port location 134*-157.2’ Inlet <span class="hlt">Wave</span> * mAnagMnt Pot location 12.3*-17,0". Out let <span class="hlt">wave</span> uAnAgament port location 157.2...parameters examined were confirmed <span class="hlt">accurately</span> using one dimensional gas dynamics relationships . Most of the approaches used in <span class="hlt">wave</span> rotor design are</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040173108&hterms=death&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Ddeath','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040173108&hterms=death&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Ddeath"><span>Predicting sudden cardiac death from T <span class="hlt">wave</span> alternans of the surface electrocardiogram: promise and pitfalls</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rosenbaum, D. S.; Albrecht, P.; Cohen, R. J.</p> <p>1996-01-01</p> <p>Sudden cardiac death remains a preeminent public health problem. Despite advances in preventative treatment for patients known to be at risk, to date we have been able to identify, and thus treat, only a small minority of these patients. Therefore, there is a major need to develop noninvasive diagnostic technologies to identify patients at risk. Recent studies have demonstrated that measurement of microvolt-level T <span class="hlt">wave</span> alternans is a promising technique for the <span class="hlt">accurate</span> identification of patients at risk for ventricular arrhythmias and sudden cardiac death. In this article, we review the clinical data establishing the relationship between microvolt T <span class="hlt">wave</span> alternans and susceptibility to ventricular arrhythmias. We also review the methods and technology that have been developed to measure microvolt levels of T <span class="hlt">wave</span> alternans noninvasively in broad populations of ambulatory patients. In particular, we examine techniques that permit the <span class="hlt">accurate</span> measurement of T <span class="hlt">wave</span> alternans during exercise stress testing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhDT........56A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhDT........56A"><span>On the Interaction Between Gravity <span class="hlt">Waves</span> and Atmospheric Thermal Tides</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Agner, Ryan Matthew</p> <p></p> <p>Gravity <span class="hlt">waves</span> and thermal tides are two of the most important dynamical features of the atmosphere. They are both generated in the lower atmosphere and propagate upward transporting energy and momentum to the upper atmosphere. This dissertation focuses on the interaction of these <span class="hlt">waves</span> in the Mesosphere and Lower Thermosphere (MLT) region of the atmosphere using both observational data and Global Circulation Model (GCMs). The first part of this work focuses on observations of gravity <span class="hlt">wave</span> interactions with the tides using both LIDAR data at the Star Fire Optical Range (SOR, 35?N, 106.5?W) and a meteor radar data at the Andes LIDAR Observatory (ALO, 30.3?S, 70.7?W). At SOR, the gravity <span class="hlt">waves</span> are shown to enhance or damp the amplitude of the diurnal <span class="hlt">variations</span> dependent on altitude while the phase is always delayed. The results compare well with previous mechanistic model results and with the Japanese Atmospheric General circulation model for Upper Atmosphere Research (JAGUAR) high resolution global circulation model. The meteor radar observed the GWs to almost always enhance the tidal amplitudes and either delay or advance the phase depending on the altitude. When compared to previous radar results from the same meteor radar when it was located in Maui, Hawaii, the Chile results are very similar while the LIDAR results show significant differences. This is because of several instrument biases when calculating GW momentum fluxes that is not significant when determining the winds. The radar needs to perform large amounts of all-sky averaging across many weeks, while the LIDAR directly detects <span class="hlt">waves</span> in a small section of sky. The second part of this work focuses on gravity <span class="hlt">wave</span> parameterization scheme effects on the tides in GCMs. The Specified Dynamics Whole Atmosphere Community Climate Model (SD-WACCM) and the extended Canadian Middle Atmosphere Model (eCMAM) are used for this analysis. The gravity <span class="hlt">wave</span> parameterization schemes in the eCMAM (Hines scheme) have been</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010cosp...38..245K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010cosp...38..245K"><span>Characteristics of offshore extreme wind-<span class="hlt">waves</span> detected by surface drifters with a low-cost GPS <span class="hlt">wave</span> sensor</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Komatsu, Kosei</p> <p></p> <p>Wind-generated <span class="hlt">waves</span> have been recognized as one of the most important factors of the sea surface roughness which plays crucial roles in various air-sea interactions such as energy, mo-mentum, heat and gas exchanges. At the same time, wind <span class="hlt">waves</span> with extreme <span class="hlt">wave</span> heights representatively called as freak or rogue <span class="hlt">waves</span> have been a matter of great concern for many people involved in shipping, fishing, constracting, surfing and other marine activities, because such extreme <span class="hlt">waves</span> frequently affect on the marine activities and sometimes cause serious dis-asters. Nevertheless, investigations of actual conditions for the evolution of wind <span class="hlt">waves</span> in the offshore region are less and sparse in contrast to dense monitoring networks in the coastal re-gions because of difficulty of offshore observation with high accuracy. Recently <span class="hlt">accurate</span> in situ observation of offshore wind <span class="hlt">waves</span> is getting possible at low cost owing to a <span class="hlt">wave</span> height and di-rection sensor developed by Harigae et al. (2004) by installing a point-positioning GPS receiver on a surface drifting buoy. The point-positioning GPS sensor can extract three dimensional movements of the buoy excited by ocean <span class="hlt">waves</span> with minimizing effects of GPS point-positioning errors through the use of a high-pass filter. Two drifting buoys equipped with the GPS-based <span class="hlt">wave</span> sensor charged by solar cells were drifted in the western North Pacific and one of them continued to observe wind <span class="hlt">waves</span> during 16 months from Sep. 2007. The RMSE of the GPS-based <span class="hlt">wave</span> sensor was less than 10cm in significant <span class="hlt">wave</span> height and about 1s in significant <span class="hlt">wave</span> period in comparison with other sensors, i.e. accelerometers installed on drifting buoys of Japan Meteorological Agency, ultrasonic sensors placed at the Hiratsuka observation station of the University of Tokyo and altimeter of the JASON-1. The GPS-based <span class="hlt">wave</span> buoys enabled us to detect freak <span class="hlt">waves</span> defined as <span class="hlt">waves</span> whose height is more than twice the significant <span class="hlt">wave</span> height. The observation conducted by</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AIPC.1955d0052L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AIPC.1955d0052L"><span>A research about characteristics of longitudinal <span class="hlt">variations</span> of ES layers irregularities based on CHAMP occultation measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liao, Sunmin</p> <p>2018-04-01</p> <p>Based on the data of CHAMP occultation measurements, this paper makes a preliminary analysis of the longitudinal <span class="hlt">variations</span> of ES irregular structure by using Fourier decomposition and reconstruction technique. It is found that the longitudinal <span class="hlt">variations</span> of the ES irregular structure show the features of multiple <span class="hlt">wave</span>-numbers, which is dominated by the <span class="hlt">wave</span> number 1 to the <span class="hlt">wave</span> number 5 components, and decrease from the amplitudes of the <span class="hlt">wave</span> number 6 components. The features of <span class="hlt">wave</span> number structures are very different in different DIP latitude and different seasons. The number of crests in summer and autumn is mostly 3 or 4 crest structures, while the number of crests in spring achieves 5 at DIP 15°N with small fluctuates, the crests number of winter is the least. In the multiple <span class="hlt">wave</span>-numbers structure, the <span class="hlt">wave</span> number 4 component shows a significant dependence on the season, mainly in the summer and autumn, particularly obvious from July to October.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhDT........17K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhDT........17K"><span>Topics in the Detection of Gravitational <span class="hlt">Waves</span> from Compact Binary Inspirals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kapadia, Shasvath Jagat</p> <p></p> <p>Orbiting compact binaries - such as binary black holes, binary neutron stars and neutron star-black hole binaries - are among the most promising sources of gravitational <span class="hlt">waves</span> observable by ground-based interferometric detectors. Despite numerous sophisticated engineering techniques, the gravitational <span class="hlt">wave</span> signals will be buried deep within noise generated by various instrumental and environmental processes, and need to be extracted via a signal processing technique referred to as matched filtering. Matched filtering requires large banks of signal templates that are faithful representations of the true gravitational waveforms produced by astrophysical binaries. The <span class="hlt">accurate</span> and efficient production of templates is thus crucial to the success of signal processing and data analysis. To that end, the dissertation presents a numerical technique that calibrates existing analytical (Post-Newtonian) waveforms, which are relatively inexpensive, to more <span class="hlt">accurate</span> fiducial waveforms that are computationally expensive to generate. The resulting waveform family is significantly more <span class="hlt">accurate</span> than the analytical waveforms, without incurring additional computational costs of production. Certain kinds of transient background noise artefacts, called "glitches'', can masquerade as gravitational <span class="hlt">wave</span> signals for short durations and throw-off the matched-filter algorithm. Identifying glitches from true gravitational <span class="hlt">wave</span> signals is a highly non-trivial exercise in data analysis which has been attempted with varying degrees of success. We present here a machine-learning based approach that exploits the various attributes of glitches and signals within detector data to provide a classification scheme that is a significant improvement over previous methods. The dissertation concludes by investigating the possibility of detecting a non-linear DC imprint, called the Christodoulou memory, produced in the arms of ground-based interferometers by the recently detected gravitational <span class="hlt">waves</span>. The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970003539','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970003539"><span>Observations of Radar Backscatter at Ku and C Bands in the Presence of Large <span class="hlt">Waves</span> during the Surface <span class="hlt">Wave</span> Dynamics Experiment</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nghiem, S. V.; Li, Fuk K.; Lou, Shu-Hsiang; Neumann, Gregory; McIntosh, Robert E.; Carson, Steven C.; Carswell, James R.; Walsh, Edward J.; Donelan, Mark A.; Drennan, William M.</p> <p>1995-01-01</p> <p>Ocean radar backscatter in the presence of large <span class="hlt">waves</span> is investigated using data acquired with the Jet Propulsion Laboratory NUSCAT radar at Ku band for horizontal and vertical polarizations and the University of Massachusetts CSCAT radar at C band for vertical polarization during the Surface <span class="hlt">Wave</span> Dynamics Experiment. Off-nadir backscatter data of ocean surfaces were obtained in the presence of large <span class="hlt">waves</span> with significant <span class="hlt">wave</span> height up to 5.6 m. In moderate-wind cases, effects of large <span class="hlt">waves</span> are not detectable within the measurement uncertainty and no noticeable correlation between backscatter coefficients and <span class="hlt">wave</span> height is found. Under high-<span class="hlt">wave</span> light-wind conditions, backscatter is enhanced significantly at large incidence angles with a weaker effect at small incidence angles. Backscatter coefficients in the wind speed range under consideration are compared with SASS-2 (Ku band), CMOD3-H1 (C band), and Plant's model results which confirm the experimental observations. <span class="hlt">Variations</span> of the friction velocity, which can give rise to the observed backscatter behaviors in the presence of large <span class="hlt">waves</span>, are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AcMSn..29..494X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AcMSn..29..494X"><span>Numerical study on <span class="hlt">wave</span> loads and motions of two ships advancing in <span class="hlt">waves</span> by using three-dimensional translating-pulsating source</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xu, Yong; Dong, Wen-Cai</p> <p>2013-08-01</p> <p>A frequency domain analysis method based on the three-dimensional translating-pulsating (3DTP) source Green function is developed to investigate <span class="hlt">wave</span> loads and free motions of two ships advancing on parallel course in <span class="hlt">waves</span>. Two experiments are carried out respectively to measure the <span class="hlt">wave</span> loads and the freemotions for a pair of side-byside arranged ship models advancing with an identical speed in head regular <span class="hlt">waves</span>. For comparison, each model is also tested alone. Predictions obtained by the present solution are found in favorable agreement with the model tests and are more <span class="hlt">accurate</span> than the traditional method based on the three dimensional pulsating (3DP) source Green function. Numerical resonances and peak shift can be found in the 3DP predictions, which result from the <span class="hlt">wave</span> energy trapped in the gap between two ships and the extremely inhomogeneous <span class="hlt">wave</span> load distribution on each hull. However, they can be eliminated by 3DTP, in which the speed affects the free surface and most of the <span class="hlt">wave</span> energy can be escaped from the gap. Both the experiment and the present prediction show that hydrodynamic interaction effects on <span class="hlt">wave</span> loads and free motions are significant. The present solver may serve as a validated tool to predict <span class="hlt">wave</span> loads and motions of two vessels under replenishment at sea, and may help to evaluate the hydrodynamic interaction effects on the ships safety in replenishment operation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AnMP....8...57B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AnMP....8...57B"><span>Convective <span class="hlt">wave</span> breaking in the KdV equation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brun, Mats K.; Kalisch, Henrik</p> <p>2018-03-01</p> <p>The KdV equation is a model equation for <span class="hlt">waves</span> at the surface of an inviscid incompressible fluid, and it is well known that the equation describes the evolution of unidirectional <span class="hlt">waves</span> of small amplitude and long wavelength fairly <span class="hlt">accurately</span> if the <span class="hlt">waves</span> fall into the Boussinesq regime. The KdV equation allows a balance of nonlinear steepening effects and dispersive spreading which leads to the formation of steady <span class="hlt">wave</span> profiles in the form of solitary <span class="hlt">waves</span> and cnoidal <span class="hlt">waves</span>. While these <span class="hlt">wave</span> profiles are solutions of the KdV equation for any amplitude, it is shown here that there for both the solitary and the cnoidal <span class="hlt">waves</span>, there are critical amplitudes for which the horizontal component of the particle velocity matches the phase velocity of the <span class="hlt">wave</span>. Solitary or cnoidal solutions of the KdV equation which surpass these amplitudes feature incipient <span class="hlt">wave</span> breaking as the particle velocity exceeds the phase velocity near the crest of the <span class="hlt">wave</span>, and the model breaks down due to violation of the kinematic surface boundary condition. The condition for breaking can be conveniently formulated as a convective breaking criterion based on the local Froude number at the <span class="hlt">wave</span> crest. This breaking criterion can also be applied to time-dependent situations, and one case of interest is the development of an undular bore created by an influx at a lateral boundary. It is shown that this boundary forcing leads to <span class="hlt">wave</span> breaking in the leading <span class="hlt">wave</span> behind the bore if a certain threshold is surpassed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29629427','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29629427"><span>Reference Values for Shear <span class="hlt">Wave</span> Elastography of Neck and Shoulder Muscles in Healthy Individuals.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ewertsen, Caroline; Carlsen, Jonathan; Perveez, Mohammed Aftab; Schytz, Henrik</p> <p>2018-01-01</p> <p>to establish reference values for ultrasound shear-<span class="hlt">wave</span> elastography for pericranial muscles in healthy individuals (m. trapezius, m. splenius capitis, m. semispinalis capitis, m. sternocleidomastoideus and m. masseter). Also to evaluate day-to-day <span class="hlt">variations</span> in the shear-<span class="hlt">wave</span> speeds and evaluate the effect of the pennation of the muscle fibers, ie scanning parallel or perpendicularly to the fibers. 10 healthy individuals (5 males and 5 females) had their pericranial muscles examined with shear-<span class="hlt">wave</span> elastography in two orthogonal planes on two different days for their dominant and non-dominant side. Mean shear <span class="hlt">wave</span> speeds from 5 ROI's in each muscle, for each scan plane for the dominant and non-dominant side for the two days were calculated. The effect of the different parameters - muscle pennation, gender, dominant vs non-dominant side and day was evaluated. The effect of scan plane in relation to muscle pennation was statistically significant (p<0.0001). The mean shear-<span class="hlt">wave</span> speed when scanning parallel to the muscle fibers was significantly higher than the mean shear-<span class="hlt">wave</span> speed when scanning perpendicularly to the fibers. The day-to-day <span class="hlt">variation</span> was statistically significant (p=0.0258), but not clinically relevant. Shear-<span class="hlt">wave</span> speeds differed significantly between muscles. Mean shear <span class="hlt">wave</span> speeds (m/s) for the muscles in the parallel plane were: for masseter 2.45 (SD:+/-0.25), semispinal 3.36 (SD:+/-0.75), splenius 3.04 (SD:+/-0.65), sternocleidomastoid 2.75 (SD:+/-0.23), trapezius 3.20 (SD:+/-0.27) and trapezius lateral 3.87 (SD:+/-3.87). The shear <span class="hlt">wave</span> speed <span class="hlt">variation</span> depended on the direction of scanning. Shear <span class="hlt">wave</span> elastography may be a method to evaluate muscle stiffness in patients suffering from chronic neck pain.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1919141S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1919141S"><span><span class="hlt">Wave</span> resource variability: Impacts on <span class="hlt">wave</span> power supply over regional to international scales</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, Helen; Fairley, Iain; Robertson, Bryson; Abusara, Mohammad; Masters, Ian</p> <p>2017-04-01</p> <p>The intermittent, irregular and variable nature of the <span class="hlt">wave</span> energy resource has implications for the supply of <span class="hlt">wave</span>-generated electricity into the grid. Intermittency of renewable power may lead to frequency and voltage fluctuations in the transmission and distribution networks. A matching supply of electricity must be planned to meet the predicted demand, leading to a need for gas-fired and back-up generating plants to supplement intermittent supplies, and potentially limiting the integration of intermittent power into the grid. Issues relating to resource intermittency and their mitigation through the development of spatially separated sites have been widely researched in the wind industry, but have received little attention to date in the less mature <span class="hlt">wave</span> industry. This study analyses the <span class="hlt">wave</span> resource over three different spatial scales to investigate the potential impacts of the temporal and spatial resource variability on the grid supply. The primary focus is the Southwest UK, a region already home to multiple existing and proposed <span class="hlt">wave</span> energy test sites. Concurrent <span class="hlt">wave</span> buoy data from six locations, supported by SWAN <span class="hlt">wave</span> model hindcast data, are analysed to assess the correlation of the resource across the region and the <span class="hlt">variation</span> in <span class="hlt">wave</span> power with direction. Power matrices for theoretical nearshore and offshore devices are used to calculate the maximum step change in generated power across the region as the number of deployment sites is increased. The step change analysis is also applied across national and international spatial scales using output from the European Centre for Medium-range Weather Forecasting (ECMWF) ERA-Interim hindcast model. It is found that the deployment of multiple <span class="hlt">wave</span> energy sites, whether on a regional, national or international scale, results in both a reduction in step changes in power and reduced times of zero generation, leading to an overall smoothing of the <span class="hlt">wave</span>-generated electrical power. This has implications for the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSEC11A..04B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSEC11A..04B"><span>Lidar Observations of <span class="hlt">Wave</span> Shape</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brodie, K. L.; Raubenheimer, B.; Spore, N.; Gorrell, L.; Slocum, R. K.; Elgar, S.</p> <p>2016-02-01</p> <p>As <span class="hlt">waves</span> propagate across the inner-surf zone, through a shorebreak, to the swash, their shapes can evolve rapidly, particularly if there are large changes in water depth over a wavelength. As <span class="hlt">wave</span> shapes evolve, the time history of near-bed <span class="hlt">wave</span>-orbital velocities also changes. Asymmetrical near-bed velocities result in preferential directions for sediment transport, and spatial <span class="hlt">variations</span> in asymmetries can lead to morphological evolution. Thus, understanding and predicting <span class="hlt">wave</span> shapes in the inner-surf and swash zones is important to improving sediment transport predictions. Here, rapid changes in <span class="hlt">wave</span> shape, quantified by 3rd moments (skewness and asymmetry) of the sea-surface elevation time series, were observed on a sandy Atlantic Ocean beach near Duck, NC using terrestrial lidar scanners that measure the elevation of the water surface along a narrow cross-shore transect with high spatial [O(1 cm)] and temporal [O(0.5 s)] resolution. The terrestrial lidar scanners were mounted on a tower on the beach dune (about 8 m above the water surface) and on an 8-m tall amphibious tripod [the Coastal Research Amphibious Buggy (CRAB)]. Observations with the dune lidar are used to investigate how bulk <span class="hlt">wave</span> shape parameters such as <span class="hlt">wave</span> skewness and asymmetry, and the ratio of <span class="hlt">wave</span> height to water depth (gamma) vary with beach slope, tide level, and offshore <span class="hlt">wave</span> conditions. Observations with the lidar mounted on the CRAB are used to investigate the evolution of individual <span class="hlt">waves</span> propagating across the surf zone and shorebreak to the swash. For example, preliminary observations from the CRAB include a <span class="hlt">wave</span> that appeared to shoal and then "pitch" backwards immediately prior to breaking and running up the beach. Funded by the USACE Coastal Field Data Collection Program, ASD(R&E), and ONR.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70032322','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70032322"><span><span class="hlt">Wave</span>-current interaction in Willapa Bay</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Olabarrieta, Maitane; Warner, John C.; Kumar, Nirnimesh</p> <p>2011-01-01</p> <p>This paper describes the importance of <span class="hlt">wave</span>-current interaction in an inlet-estuary system. The three-dimensional, fully coupled, Coupled Ocean-Atmosphere-<span class="hlt">Wave</span>-Sediment Transport (COAWST) modeling system was applied in Willapa Bay (Washington State) from 22 to 29 October 1998 that included a large storm event. To represent the interaction between <span class="hlt">waves</span> and currents, the vortex-force method was used. Model results were compared with water elevations, currents, and <span class="hlt">wave</span> measurements obtained by the U.S. Army Corp of Engineers. In general, a good agreement between field data and computed results was achieved, although some discrepancies were also observed in regard to <span class="hlt">wave</span> peak directions in the most upstream station. Several numerical experiments that considered different forcing terms were run in order to identify the effects of each wind, tide, and <span class="hlt">wave</span>-current interaction process. Comparison of the horizontal momentum balances results identified that <span class="hlt">wave</span>-breaking-induced acceleration is one of the leading terms in the inlet area. The enhancement of the apparent bed roughness caused by <span class="hlt">waves</span> also affected the values and distribution of the bottom shear stress. The pressure gradient showed significant changes with respect to the pure tidal case. During storm conditions the momentum balance in the inlet shares the characteristics of tidal-dominated and <span class="hlt">wave</span>-dominated surf zone environments. The changes in the momentum balance caused by <span class="hlt">waves</span> were manifested both in water level and current <span class="hlt">variations</span>. The most relevant effect on hydrodynamics was a <span class="hlt">wave</span>-induced setup in the inner part of the estuary.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140011424','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140011424"><span>Modeling Mars Cyclogenesis and Frontal <span class="hlt">Waves</span>: Seasonal <span class="hlt">Variations</span> and Implications on Dust Activity</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hollingsworth, J. L.; Kahre, M. A.</p> <p>2014-01-01</p> <p>Between late autumn through early spring,middle and high latitudes onMars exhibit strong equator-to-polemean temperature contrasts (i.e., "baroclinicity"). Data collected during the Viking era and observations from both the Mars Global Surveyor (MGS) and Mars Reconnaissance Orbiter (MRO) indicate that such strong baroclinicity supports vigorous, large-scale eastward traveling weather systems (i.e., transient synoptic period <span class="hlt">waves</span>) [1, 2]. For a rapidly rotating, differentially heated, shallow atmosphere such as on Earth and Mars, these large-scale, extratropical weather disturbances are critical components of the global circulation. The <span class="hlt">wave</span>-like disturbances serve as agents in the transport of heat and momentum between low and high latitudes of the planet. Through cyclonic/anticyclonic winds, intense shear deformations, contractions-dilatations in temperature and density, and sharp perturbations amongst atmospheric tracers (i.e., dust, volatiles (e.g., water vapor) and condensates (e.g., water-ice cloud particles)), Mars' extratropical weather systems have significant sub-synoptic scale ramifications by supporting atmospheric frontal <span class="hlt">waves</span> (Fig. 1).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/21611797-chirped-pulse-millimeter-wave-spectroscopy-rydberg-rydberg-transitions','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/21611797-chirped-pulse-millimeter-wave-spectroscopy-rydberg-rydberg-transitions"><span>Chirped-Pulse Millimeter-<span class="hlt">Wave</span> Spectroscopy of Rydberg-Rydberg Transitions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Prozument, Kirill; Colombo, Anthony P.; Zhou Yan</p> <p>2011-09-30</p> <p>Transitions between Rydberg states of Ca atoms, in a pulsed, supersonic atomic beam, are directly detected by chirped-pulse millimeter-<span class="hlt">wave</span> spectroscopy. Broadband, high-resolution spectra with <span class="hlt">accurate</span> relative intensities are recorded instantly. Free induction decay (FID) of atoms, polarized by the chirped pulse, at their Rydberg-Rydberg transition frequencies, is heterodyne detected, averaged in the time domain, and Fourier transformed into the frequency domain. Millimeter-<span class="hlt">wave</span> transient nutations are observed, and the possibility of FID evolving to superradiance is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22370359-synthetic-observations-wave-propagation-sunspot-umbra','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22370359-synthetic-observations-wave-propagation-sunspot-umbra"><span>Synthetic observations of <span class="hlt">wave</span> propagation in a sunspot umbra</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Felipe, T.; Socas-Navarro, H.; Khomenko, E.</p> <p>2014-11-01</p> <p>Spectropolarimetric temporal series from Fe I λ6301.5 Å and Ca II infrared triplet lines are obtained by applying the Stokes synthesis code NICOLE to a numerical simulation of <span class="hlt">wave</span> propagation in a sunspot umbra from MANCHA code. The analysis of the phase difference between Doppler velocity and intensity core oscillations of the Fe I λ6301.5 Å line reveals that <span class="hlt">variations</span> in the intensity are produced by opacity fluctuations rather than intrinsic temperature oscillations, except for frequencies between 5 and 6.5 mHz. On the other hand, the photospheric magnetic field retrieved from the weak field approximation provides the intrinsic magnetic fieldmore » oscillations associated to <span class="hlt">wave</span> propagation. Our results suggest that this is due to the low magnetic field gradient of our sunspot model. The Stokes parameters of the chromospheric Ca II infrared triplet lines show striking <span class="hlt">variations</span> as shock <span class="hlt">waves</span> travel through the formation height of the lines, including emission self-reversals in the line core and highly abnormal Stokes V profiles. Magnetic field oscillations inferred from the Ca II infrared lines using the weak field approximation appear to be related with the magnetic field strength <span class="hlt">variation</span> between the photosphere and the chromosphere.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19740015177','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740015177"><span>Amplitude <span class="hlt">variations</span> of whistler-mode signals caused by their interaction with energetic electrons of the magnetosphere</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bernard, L. C.</p> <p>1973-01-01</p> <p>Whistler mode <span class="hlt">waves</span> that propagate through the magnetosphere exchange energy with energetic electrons by <span class="hlt">wave</span>-particle interaction mechanisms. Using linear theory, a detailed investigation is presented of the resulting amplitude <span class="hlt">variations</span> of the <span class="hlt">wave</span> as it propagates. Arbitrary <span class="hlt">wave</span> frequency and direction of propagation are considered. A general class of electron distributions that are nonseparable in particle energy and pitch-angle is proposed. It is found that the proposed distribution model is consistent with available whistler and particle observations. This model yields insignificant amplitude <span class="hlt">variation</span> over a large frequency band, a feature commonly observed in whistler data. This feature implies a certain equilibrium between <span class="hlt">waves</span> and particles in the magnetosphere over a wide spread of particle energy, and is relevant to plasma injection experiments and to monitoring the distribution of energetic electrons in the magnetosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20030112972&hterms=Lower+class&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DLower%2Bclass','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20030112972&hterms=Lower+class&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DLower%2Bclass"><span>Modeling Study of Planetary <span class="hlt">Waves</span> in the Mesosphere Lower Thermosphere (MLT)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mengel, J. G.; Mayr, H. g.; Drob, D.; Porter, H. S.; Hines, C. O.</p> <p>2003-01-01</p> <p>For comparison with measurements from the TIMED satellite and coordinated ground based observations, we present results from our Numerical Spectral Model (NSM) that incorporates the Doppler Spread Parameterization (Hines, 1997) for small-scale gravity <span class="hlt">waves</span> (GWs). We discuss the planetary <span class="hlt">waves</span> (PWs) that are purely generated by dynamical interactions, i.e., without explicitly specifying excitation sources related for example to tropospheric convection or topography. With tropospheric heating that reproduces the observed zonal jets near the tropopause and the accompanying reversal in the latitudinal temperature <span class="hlt">variation</span>, which is conducive to baroclinic instability, long period PWs are produced that propagate up into the stratosphere to affect the <span class="hlt">wave</span> driven equatorial oscillations (QBO and SAO) extending into the upper mesosphere. The PWs in the model that dominate higher up in the MLT region, however, are to a large extent produced by instabilities under the influence of the zonal circulation and temperature <span class="hlt">variations</span> in the middle atmosphere and they are amplified by GW interactions. Three classes of PWs are generated there. (1) Rossby <span class="hlt">waves</span> that slowly propagate westward but are carried by the zonal mean (m = 0) winds to produce eastward and westward propagating PWs respectively in the winter and summer hemispheres below 80 km. Depending on the zonal <span class="hlt">wave</span> number and magnitudes of the zonal winds under the influence of the equatorial oscillations, the PWs typically have periods between 2 and 20 days and their horizontal wind amplitudes can exceed 40 m/s in the lower mesosphere. (2) Rossby gravity <span class="hlt">waves</span> that propagate westward at low latitudes, having periods around 2 days for zonal <span class="hlt">wave</span> numbers m = 2 to 4. (3) Eastward propagating equatorial Kelvin <span class="hlt">waves</span> generated in the upper mesosphere with periods between 2 and 3 days for m = 1 & 2. The seasonal <span class="hlt">variations</span> of the PWs reveal that the largest wind amplitudes tend to occur below 80 km in the winter hemisphere</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSA33A2580Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSA33A2580Z"><span>Persistent gravity <span class="hlt">wave</span> coupling from the stratosphere to the MLT versus secondary <span class="hlt">wave</span> generation in Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhao, J.; Geraghty, I.; Chu, X.; Vadas, S.; Becker, E.; Harvey, V. L.; Jones, R. M.; Chen, C.; Lu, X.</p> <p>2017-12-01</p> <p>After Antarctic persistent gravity <span class="hlt">waves</span> (GWs) in the Mesosphere and Lower Thermosphere (MLT) were discovered from lidar observations [Chen et al., 2013, 2016], secondary <span class="hlt">wave</span> generation theory was proposed to explain the source. Here we perform a source investigation of such persistent GWs through analyzing both stratospheric and MLT GWs at McMurdo using temperature measurements (30 - 50 km, year 2011 - 2015) obtained by Fe Boltzmann lidar. In the stratosphere, GW vertical wavelengths (λ) and periods exhibit seasonal cycles with winter maxima and summer minima, which linearly correlated with mean zonal wind velocities. GWs dissipate more in winter than in summer due to larger <span class="hlt">wave</span> amplitudes. The potential energy density (Ep) are anti-correlated with wind rotation angles but positively correlated with surface and stratospheric winds. Critical level filtering, in-situ generation of GWs, and <span class="hlt">wave</span> saturation changes play roles in Ep seasonal <span class="hlt">variations</span> (winter maxima and summer minima). The large increase of Ep from summer to winter possibly results from the decrease in critical level filtering. The gradual <span class="hlt">variations</span> of Ep from Mar to Oct are likely related both to the increased λ towards winter, allowing larger <span class="hlt">wave</span> amplitudes before saturation, and to in-situ GW generation via geostrophic adjustment, secondary GW generation. Large Ep occur when McMurdo is inside the jet stream core 5-24º poleward from vortex edge. In winter MLT, the persistent GWs cause larger temperature perturbations (± 30 K, compared to ± 10 K in the stratosphere) with longer λ (23.5 km) and larger vertical phase speeds (1.8 m/s). More <span class="hlt">waves</span> (95.4%) show downward phase progression compared to the stratospheric GWs (70.4%). Since the inferred horizontal wavelength of stratospheric GWs (350 - 450 km) are much shorter than those of the persistent GWs in the MLT (1000 - 2000 km), the dominant stratospheric GWs are not the direct source of the MLT persistent GWs. Secondary <span class="hlt">wave</span> generation</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002APhy...48...34V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002APhy...48...34V"><span>Transformation of Elastic <span class="hlt">Wave</span> Energy to the Energy of Motion of Bodies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vesnitskiĭ, A. I.; Lisenkova, E. E.</p> <p>2002-01-01</p> <p>The motion of a body along an elastic guide under the effect of an incident <span class="hlt">wave</span> is considered. An equation describing the longitudinal motion of a body along an arbitrary guide is derived from the laws governing the energy and momentum <span class="hlt">variations</span> for the case when the incident <span class="hlt">wave</span> generates a single reflected <span class="hlt">wave</span>. The equations that describe the motion of a body along a string and along a beam corresponding to the Bernoulli-Euler model are considered as examples. The process of the body acceleration along a beam of the aforementioned type is investigated. For the subcritical velocities, the law governing the motion of the body and the ratio of the kinetic energy <span class="hlt">variation</span> to the energy supplied to the body are determined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20030093552','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20030093552"><span>Inertio Gravity <span class="hlt">Waves</span> in the Upper Mesosphere</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mayr, H. G.; Mengel, J. G.; Talaat, E. L.; Porter, H. S.; Chan, K. L.</p> <p>2003-01-01</p> <p>In the polar region of the upper mesosphere, horizontal wind oscillations have been observed with periods around 10 hours (Hernandez et al., 1992). Such <span class="hlt">waves</span> are generated in our Numerical Spectral Model (NSM) and appear to be inertio gravity <span class="hlt">waves</span> (IGW). Like the planetary <span class="hlt">waves</span> (PW) in the model, the IGWs are generated by instabilities that arise in the mean zonal circulation. In addition to stationary <span class="hlt">waves</span> for m = 0, eastward and westward propagating <span class="hlt">waves</span> for m = 1 to 4 appear above 70 km that grow in magnitude up to about 110 km, having periods between 9 and 11 hours. The m = 1 westward propagating IGWs have the largest amplitudes, which can reach at the poles 30 m/s. Like PWs, the IGWs are intermittent but reveal systematic seasonal <span class="hlt">variations</span>, with the largest amplitudes occurring generally in winter and spring. The IGWs propagate upward with a vertical wavelength of about 20 km.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19810012780','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19810012780"><span>On the pressure field of nonlinear standing water <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schwartz, L. W.</p> <p>1980-01-01</p> <p>The pressure field produced by two dimensional nonlinear time and space periodic standing <span class="hlt">waves</span> was calculated as a series expansion in the <span class="hlt">wave</span> height. The high order series was summed by the use of Pade approximants. Calculations included the pressure <span class="hlt">variation</span> at great depth, which was considered to be a likely cause of microseismic activity, and the pressure distribution on a vertical barrier or breakwater.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JPhCS1006a2007B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JPhCS1006a2007B"><span>Potency of sensor displacement detection of cholesterol concentration using flat mirror as media for learning <span class="hlt">waves</span> and optics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Budiyanto, M.; Suhariningsih; Yasin, M.</p> <p>2018-04-01</p> <p>The use of instructional media needs to be implemented in one of the courses such as <span class="hlt">wave</span> and optics to cover up the contents of material. To bring this advantage, one of the alternatives that can be used is to use fiber optic sensors for detecting cholesterol concentration. This device brings about the concepts of how the <span class="hlt">wave</span> and optics behaves and operates. In doing so, the <span class="hlt">variation</span> concentration of cholesterol solution is 0 ppm, 50 ppm, 100 ppm, 150 ppm, 200 ppm, 250 ppm, and 300 ppm. The work mechanism of cholesterol concentration detection is laser propagation of He-Ne wavelength 632.5 nm through fiber optic in cholesterol solution and reflected back by flat mirror then ray reflected through fiber optic bundle so detected by SL-818 silicon detector in the form of voltage Output. The detection results showed that the maximum output voltage showed a linear decrease in the concentration of cholesterol solution with a sensitivity of 0.21 mV/ppm and linearity of more than 95%. In terms of developed learning media, the use of optical fiber sensor learning media is compatible with optical <span class="hlt">wave</span> learning in terms of basic competence of lectures, learning indicators, learning materials, student worksheets and science process skills. From the assessment of validation of learning media obtained an assessment of more than 95%. The results of this study indicate the parameters and performance of sensors that have <span class="hlt">accurate</span> potential as a medium for learning <span class="hlt">wave</span> and optics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013OcMod..70..152B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013OcMod..70..152B"><span><span class="hlt">Wave</span>-current interaction: Effect on the <span class="hlt">wave</span> field in a semi-enclosed basin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Benetazzo, A.; Carniel, S.; Sclavo, M.; Bergamasco, A.</p> <p>2013-10-01</p> <p> investigations reveal that, when applied to intense storms, the effect of coupling on <span class="hlt">waves</span> results in <span class="hlt">variations</span> of significant <span class="hlt">wave</span> height up to 0.6 m, with some areas experiencing significant increase/decrease of <span class="hlt">wave</span> spectral energy for opposite/following currents respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001Natur.414..716G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001Natur.414..716G"><span>Travelling <span class="hlt">waves</span> and spatial hierarchies in measles epidemics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grenfell, B. T.; Bjørnstad, O. N.; Kappey, J.</p> <p>2001-12-01</p> <p>Spatio-temporal travelling <span class="hlt">waves</span> are striking manifestations of predator-prey and host-parasite dynamics. However, few systems are well enough documented both to detect repeated <span class="hlt">waves</span> and to explain their interaction with spatio-temporal <span class="hlt">variations</span> in population structure and demography. Here, we demonstrate recurrent epidemic travelling <span class="hlt">waves</span> in an exhaustive spatio-temporal data set for measles in England and Wales. We use wavelet phase analysis, which allows for dynamical non-stationarity-a complication in interpreting spatio-temporal patterns in these and many other ecological time series. In the pre-vaccination era, conspicuous hierarchical <span class="hlt">waves</span> of infection moved regionally from large cities to small towns; the introduction of measles vaccination restricted but did not eliminate this hierarchical contagion. A mechanistic stochastic model suggests a dynamical explanation for the <span class="hlt">waves</span>-spread via infective `sparks' from large `core' cities to smaller `satellite' towns. Thus, the spatial hierarchy of host population structure is a prerequisite for these infection <span class="hlt">waves</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRA..123.3460R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRA..123.3460R"><span>One-Hertz <span class="hlt">Waves</span> at Mars: MAVEN Observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ruhunusiri, Suranga; Halekas, J. S.; Espley, J. R.; Eparvier, F.; Brain, D.; Mazelle, C.; Harada, Y.; DiBraccio, G. A.; Thiemann, E. M. B.; Larson, D. E.; Mitchell, D. L.; Jakosky, B. M.; Sulaiman, A. H.</p> <p>2018-05-01</p> <p>We perform a survey of 1-Hz <span class="hlt">waves</span> at Mars utilizing Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft observations for a Martian year. We find that the 1-Hz <span class="hlt">wave</span> occurrence rate shows an apparent <span class="hlt">variation</span> caused by masking of the <span class="hlt">waves</span> by background turbulence during the times when the background turbulence levels are high. To correct for this turbulence masking, we select <span class="hlt">waves</span> that occur in time intervals where the background turbulence levels are low. We find that the extreme ultraviolet flux does not affect the <span class="hlt">wave</span> occurrence rate significantly, suggesting that the newly born pickup ions originating in the Mars's exosphere contribute minimally to the 1-Hz <span class="hlt">wave</span> generation. We find that the <span class="hlt">wave</span> occurrence rates are higher for low Mach numbers and low beta values than for high Mach numbers and high beta values. Further, we find that a high percentage of 1-Hz <span class="hlt">waves</span> satisfy the group-standing condition, which suggests that a high percentage of the <span class="hlt">waves</span> seen as monochromatic <span class="hlt">waves</span> in the spacecraft frame can be broadband <span class="hlt">waves</span> in the solar wind frame that have group velocities nearly equal and opposite to the solar wind velocity. We infer that the <span class="hlt">wave</span> occurrence rate trends with the Mach number and proton beta are a consequence of how the Mach numbers and beta values influence the <span class="hlt">wave</span> generation and damping or how those parameters affect the group-standing condition. Finally, we find that the 1-Hz <span class="hlt">waves</span> are equally likely to be found in both the quasi-parallel and the quasi-perpendicular foreshock regions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20030093643','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20030093643"><span>Non-Migrating Diurnal Tides Generated with Planetary <span class="hlt">Waves</span> in the Mesosphere</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mayr, H. G.; Mengel, J. G.; Talaat, E. R.; Porter, H. S.; Chan, K. L.</p> <p>2003-01-01</p> <p>We report here the results from a modeling study with our Numerical Spectral Model (NSM) that extends from the ground into thermosphere. The NSM incorporates Hines Doppler Spread Parameterization for small-scale gravity <span class="hlt">waves</span> (GWs) and describes the major dynamical features of the atmosphere, including the <span class="hlt">wave</span> driven equatorial oscillations (QBO and SAO), and the seasonal <span class="hlt">variations</span> of tides and planetary <span class="hlt">waves</span>. Accounting solely for the solar migrating tidal excitation sources, the NSM generates through dynamical interactions also non-migrating tides in the mesosphere that have amplitudes comparable to those observed. The model produces the diurnal (and semidiurnal) oscillations of the zonal mean (m = 0), and eastward and westward propagating tides for zonal <span class="hlt">wave</span> numbers m = 1 to 4. To identify the mechanism of excitation for these tides, a numerical experiment is performed. The NSM is run without the heat source for the zonal-mean circulation and temperature <span class="hlt">variation</span>, and the amplitudes of the resulting nonmigrating tides are then negligibly small. This leads to the conclusion that the planetary <span class="hlt">waves</span>, which normally are excited in the NSM by instabilities but are suppressed in this case, generate the nonmigrating tides through nonlinear interactions with the migrating tides.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730013586','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730013586"><span>Relations among low ionosphere parameters and high frequency radio <span class="hlt">wave</span> absorption</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cipriano, J. P.</p> <p>1973-01-01</p> <p>Charged particle conductivities measured in the very low ionosphere at White Sands Missile Range, New Mexico, and Wallops Island, Virginia, are compared with atmospheric parameters and high frequency radio <span class="hlt">wave</span> absorption measurements. Charged particle densities are derived from the conductivity data. Between 33 and 58 km, positive conductivity correlated well with neutral atmospheric temperature, with temperature coefficients as large as 4.6%/deg K. Good correlations were also found between HF radio <span class="hlt">wave</span> absorption and negative conductivity at altitudes as low as 53 km, indicating that the day-to-day absorption <span class="hlt">variations</span> were principally due to <span class="hlt">variations</span> in electron loss rate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993IJIMW..14.1471R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993IJIMW..14.1471R"><span>Strip dielectric <span class="hlt">wave</span> guide antenna-for the measurement of dielectric constant of low-loss materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rastogi, Alok Kumar; Tiwari, A. K.; Shrivastava, R. P.</p> <p>1993-07-01</p> <p>The value of dielectric constant are the most important parameters in material science technology. In micro-<span class="hlt">wave</span> and millimeter <span class="hlt">wave</span> circuits using dielectric materials the values of this parameters should be known <span class="hlt">accurately</span>. It is observed that the number of methods are reported in litrature, however these methods impose difficulties in experimentation and are not very <span class="hlt">accurate</span>. In this paper a novel approach to the measurement of the dielectric constant of low loss materials at micro-<span class="hlt">wave</span> and millimeter <span class="hlt">wave</span> frequencies has been discussed. In this method by using antenna theory, a metallic strip dielectric guide is taken in to constideration and band reject phenomenon of dielectric antenna is used. Frequency response of an antenna in band reject mode is a function of the dimensional parameters, such as the metallic strip period, the profile of the metallic strip and the dielectric constant of the material used. Hence if one measure the frequency responce of the antenna in band reject mode, the dielectric constant of the material is determined provided all other parameters are known. This method gives a direct measure of dielectric constant and is quite <span class="hlt">accurate</span> as computer techniques are used for evaluating the dielectric constant. This method verified experimentally also.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002APS..DFD.MD003Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002APS..DFD.MD003Z"><span>Numerical Investigation of Three-dimensional Instability of Standing <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhu, Qiang; Liu, Yuming; Yue, Dick K. P.</p> <p>2002-11-01</p> <p>We study the three-dimensional instability of finite-amplitude standing <span class="hlt">waves</span> under the influence of gravity using the transition matrix method. For <span class="hlt">accurate</span> calculation of the transition matrices, we apply an efficient high-order spectral element method for nonlinear <span class="hlt">wave</span> dynamics in complex domain. We consider two types of standing <span class="hlt">waves</span>: (a) plane standing <span class="hlt">waves</span>; and (b) standing <span class="hlt">waves</span> in a circular tank. For the former, in addition to the confirmation of the side-band-like instability, we find a new three-dimensional instability for arbitrary base standing <span class="hlt">waves</span>. The dominant component of the unstable disturbance is an oblique standing <span class="hlt">wave</span>, with an arbitrary angle relative to the base flow, whose frequency is approximately equal to that of the base standing <span class="hlt">wave</span>. Based on direct simulations, we confirm such a three-dimensional instability and show the occurrence of the Fermi-Pasta-Ulam recurrence phenomenon during nonlinear evolution. For the latter, we find that beyond a threshold <span class="hlt">wave</span> steepness, the standing <span class="hlt">wave</span> with frequency Ω becomes unstable to a small three-dimensional disturbance, which contains two dominant standing-<span class="hlt">wave</span> components with frequencies ω1 and ω_2, provided that 2Ω ω1 + ω_2. The threshold <span class="hlt">wave</span> steepness is found to decrease/increase as the radial/azimuthal wavenumber of the base standing <span class="hlt">wave</span> increases. We show that the instability of standing <span class="hlt">waves</span> in rectangular and circular tanks is caused by third-order quartet resonances between base flow and disturbance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1409000-structural-loads-analysis-wave-energy-converters','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1409000-structural-loads-analysis-wave-energy-converters"><span>Structural Loads Analysis for <span class="hlt">Wave</span> Energy Converters</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>van Rij, Jennifer A; Yu, Yi-Hsiang; Guo, Yi</p> <p>2017-06-03</p> <p>This study explores and verifies the generalized body-modes method for evaluating the structural loads on a <span class="hlt">wave</span> energy converter (WEC). Historically, WEC design methodologies have focused primarily on <span class="hlt">accurately</span> evaluating hydrodynamic loads, while methodologies for evaluating structural loads have yet to be fully considered and incorporated into the WEC design process. As <span class="hlt">wave</span> energy technologies continue to advance, however, it has become increasingly evident that an <span class="hlt">accurate</span> evaluation of the structural loads will enable an optimized structural design, as well as the potential utilization of composites and flexible materials, and hence reduce WEC costs. Although there are many computational fluidmore » dynamics, structural analyses and fluid-structure-interaction (FSI) codes available, the application of these codes is typically too computationally intensive to be practical in the early stages of the WEC design process. The generalized body-modes method, however, is a reduced order, linearized, frequency-domain FSI approach, performed in conjunction with the linear hydrodynamic analysis, with computation times that could realistically be incorporated into the WEC design process.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.S24A..04D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.S24A..04D"><span>Computational Modeling of Seismic <span class="hlt">Wave</span> Propagation Velocity-Saturation Effects in Porous Rocks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Deeks, J.; Lumley, D. E.</p> <p>2011-12-01</p> <p>Compressional and shear velocities of seismic <span class="hlt">waves</span> propagating in porous rocks vary as a function of the fluid mixture and its distribution in pore space. Although it has been possible to place theoretical upper and lower bounds on the velocity <span class="hlt">variation</span> with fluid saturation, predicting the actual velocity response of a given rock with fluid type and saturation remains an unsolved problem. In particular, we are interested in predicting the velocity-saturation response to various mixtures of fluids with pressure and temperature, as a function of the spatial distribution of the fluid mixture and the seismic wavelength. This effect is often termed "patchy saturation' in the rock physics community. The ability to <span class="hlt">accurately</span> predict seismic velocities for various fluid mixtures and spatial distributions in the pore space of a rock is useful for fluid detection, hydrocarbon exploration and recovery, CO2 sequestration and monitoring of many subsurface fluid-flow processes. We create digital rock models with various fluid mixtures, saturations and spatial distributions. We use finite difference modeling to propagate elastic <span class="hlt">waves</span> of varying frequency content through these digital rock and fluid models to simulate a given lab or field experiment. The resulting waveforms can be analyzed to determine seismic traveltimes, velocities, amplitudes, attenuation and other <span class="hlt">wave</span> phenomena for variable rock models of fluid saturation and spatial fluid distribution, and variable wavefield spectral content. We show that we can reproduce most of the published effects of velocity-saturation <span class="hlt">variation</span>, including validating the Voigt and Reuss theoretical bounds, as well as the Hill "patchy saturation" curve. We also reproduce what has been previously identified as Biot dispersion, but in fact in our models is often seen to be <span class="hlt">wave</span> multi-pathing and broadband spectral effects. Furthermore, we find that in addition to the dominant seismic wavelength and average fluid patch size, the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120007841','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120007841"><span>Longitudinal <span class="hlt">Variation</span> and <span class="hlt">Waves</span> in Jupiter's South Equatorial Wind Jet</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Simon-Miller, A. A.; Rogers, John H.; Gierasch, Peter J.; Choi, David; Allison, Michael; Adamoli, Gianluigi; Mettig, Hans-Joerg</p> <p>2012-01-01</p> <p>We have conducted a detailed study of the cloud features in the strong southern equatorial wind jet near 7.5 S planetographic latitude. To understand the apparent <span class="hlt">variations</span> in average zonal wind jet velocity at this latitude [e.g.. 1,2,3], we have searched for <span class="hlt">variations</span> iIi both feature latitude and velocity with longitude and time. In particular, we focused on the repetitive chevron-shaped dark spots visible on most dates and the more transient large anticyclonic system known as the South Equatorial Disturbance (SED). These small dark spots are interpreted as cloud holes, and are often used as material tracers of the wind field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRC..122.5689M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRC..122.5689M"><span>Modeling <span class="hlt">wave</span> attenuation by salt marshes in Jamaica Bay, New York, using a new rapid <span class="hlt">wave</span> model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marsooli, Reza; Orton, Philip M.; Mellor, George</p> <p>2017-07-01</p> <p>Using a new rapid-computation <span class="hlt">wave</span> model, improved and validated in the present study, we quantify the value of salt marshes in Jamaica Bay—a highly urbanized estuary located in New York City—as natural buffers against storm <span class="hlt">waves</span>. We augment the MDO phase-averaged <span class="hlt">wave</span> model by incorporating a vegetation-drag-induced energy dissipation term into its <span class="hlt">wave</span> energy balance equation. We adopt an empirical formula from literature to determine the vegetation drag coefficient as a function of environmental conditions. Model evaluation using data from laboratory-scale experiments show that the improved MDO model <span class="hlt">accurately</span> captures <span class="hlt">wave</span> height attenuation due to submerged and emergent vegetation. We apply the validated model to Jamaica Bay to quantify the influence of coastal-scale salt marshes on storm <span class="hlt">waves</span>. It is found that the impact of marsh islands is largest for storms with lower flood levels, due to <span class="hlt">wave</span> breaking on the marsh island substrate. However, the role of the actual marsh plants, Spartina alterniflora, grows larger for storms with higher flood levels, when <span class="hlt">wave</span> breaking does not occur and the vegetative drag becomes the main source of energy dissipation. For the latter case, seasonality of marsh height is important; at its maximum height in early fall, S. alterniflora causes twice the reduction as when it is at a shorter height in early summer. The model results also indicate that the vegetation drag coefficient varies 1 order of magnitude in the study area, and suggest exercising extra caution in using a constant drag coefficient in coastal wetlands.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5046142','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5046142"><span>Revisit to three-dimensional percolation theory: <span class="hlt">Accurate</span> analysis for highly stretchable conductive composite materials</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kim, Sangwoo; Choi, Seongdae; Oh, Eunho; Byun, Junghwan; Kim, Hyunjong; Lee, Byeongmoon; Lee, Seunghwan; Hong, Yongtaek</p> <p>2016-01-01</p> <p>A percolation theory based on <span class="hlt">variation</span> of conductive filler fraction has been widely used to explain the behavior of conductive composite materials under both small and large deformation conditions. However, it typically fails in properly analyzing the materials under the large deformation since the assumption may not be valid in such a case. Therefore, we proposed a new three-dimensional percolation theory by considering three key factors: nonlinear elasticity, precisely measured strain-dependent Poisson’s ratio, and strain-dependent percolation threshold. Digital image correlation (DIC) method was used to determine actual Poisson’s ratios at various strain levels, which were used to <span class="hlt">accurately</span> estimate <span class="hlt">variation</span> of conductive filler volume fraction under deformation. We also adopted strain-dependent percolation threshold caused by the filler re-location with deformation. When three key factors were considered, electrical performance change was <span class="hlt">accurately</span> analyzed for composite materials with both isotropic and anisotropic mechanical properties. PMID:27694856</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.S33A1048R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.S33A1048R"><span><span class="hlt">Variation</span> in crustal structure in Iran and the surrounding region</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rham, D.; Tatar, M.; Ashtiany, M.; Mokhtari, M.; Priestley, K.; Paul, A.</p> <p>2007-12-01</p> <p>We present a model for the topography of the Moho discontinuity for Iran and its surrounding regions. This is produced using data from field deployments within Iran by the University of Cambridge (UK) and the Universite Joseph-Fourier (FRA) in conjunction with International Institute of Earthquake Engineering and Seismology (Iran), in addition to data from IRIS and Geofone. We determine tomographic group velocity maps for periods between 10 and 60 s from multiple filter analysis of ~5500 seismograms. Because of the dense path coverage, these images have substantially higher lateral resolution for this region than is currently available from global and regional group velocity studies. Joint inversion of receiver functions and Rayleigh <span class="hlt">wave</span> dispersion give <span class="hlt">accurate</span> crustal velocity structures at 96 sites within Iran These provide a constraint for the less sharp crustal velocity profile produced by inverting the Rayleigh <span class="hlt">wave</span> dispersion curve across all of Iran. We observe <span class="hlt">variations</span> in the crustal thickness across the region, consistent with the surface topography. The thickest crust (55-60 km) is found beneath the central Zagros mountains, with the crust in the remainder of Iran having a thicknesses of 40-50 km. No significant increase in Moho depth is seen beneath the Alborz or Kopet Dagh mountains. The structure of the South Caspian Basin is presented with a different structure to that found in previous studies, with a crustal thickness of 50 km in the west, and beneath the Caucasus and Talesh mountains, in the middle part of the basin, over the course of the ~100km, this decreases to 40km, and continues to 35 km beneath the Turkmen Platform. Comparisons are also made between the joint inversion results, and <span class="hlt">accurate</span> hypocentre depths for regional earthquakes. This shows most events occur in the upper crystalline crust (~10-20km depth), with few in the lowest velocity layer. Almost no events are located in the lower crust, and only in the Makran and Aspheron</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19940015952&hterms=Global+Positioning+System&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DThe%2BGlobal%2BPositioning%2BSystem','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19940015952&hterms=Global+Positioning+System&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DThe%2BGlobal%2BPositioning%2BSystem"><span>Detection of traveling ionospheric disturbances induced by atmospheric gravity <span class="hlt">waves</span> using the global positioning system</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bassiri, Sassan; Hajj, George A.</p> <p>1993-01-01</p> <p>Natural and man-made events like earthquakes and nuclear explosions launch atmospheric gravity <span class="hlt">waves</span> (AGW) into the atmosphere. Since the particle density decreases exponentially with height, the gravity <span class="hlt">waves</span> increase exponentially in amplitude as they propagate toward the upper atmosphere and ionosphere. As atmospheric gravity <span class="hlt">waves</span> approach the ionospheric heights, the neutral particles carried by gravity <span class="hlt">waves</span> collide with electrons and ions, setting these particles in motion. This motion of charged particles manifests itself by <span class="hlt">wave</span>-like fluctuations and disturbances that are known as traveling ionospheric disturbances (TID). The perturbation in the total electron content due to TID's is derived analytically from first principles. Using the tilted dipole magnetic field approximation and a Chapman layer distribution for the electron density, the <span class="hlt">variations</span> of the total electron content versus the line-of-sight direction are numerically analyzed. The temporal <span class="hlt">variation</span> associated with the total electron content measurements due to AGW's can be used as a means of detecting characteristics of the gravity <span class="hlt">waves</span>. As an example, detection of tsunami generated earthquakes from their associated atmospheric gravity <span class="hlt">waves</span> using the Global Positioning System is simulated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhyD..301...59M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhyD..301...59M"><span>Elliptical optical solitary <span class="hlt">waves</span> in a finite nematic liquid crystal cell</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Minzoni, Antonmaria A.; Sciberras, Luke W.; Smyth, Noel F.; Worthy, Annette L.</p> <p>2015-05-01</p> <p>The addition of orbital angular momentum has been previously shown to stabilise beams of elliptic cross-section. In this article the evolution of such elliptical beams is explored through the use of an approximate methodology based on modulation theory. An approximate method is used as the equations that govern the optical system have no known exact solitary <span class="hlt">wave</span> solution. This study brings to light two distinct phases in the evolution of a beam carrying orbital angular momentum. The two phases are determined by the shedding of radiation in the form of mass loss and angular momentum loss. The first phase is dominated by the shedding of angular momentum loss through spiral <span class="hlt">waves</span>. The second phase is dominated by diffractive radiation loss which drives the elliptical solitary <span class="hlt">wave</span> to a steady state. In addition to modulation theory, the "chirp" <span class="hlt">variational</span> method is also used to study this evolution. Due to the significant role radiation loss plays in the evolution of an elliptical solitary <span class="hlt">wave</span>, an attempt is made to couple radiation loss to the chirp <span class="hlt">variational</span> method. This attempt furthers understanding as to why radiation loss cannot be coupled to the chirp method. The basic reason for this is that there is no consistent manner to match the chirp trial function to the generated radiating <span class="hlt">waves</span> which is uniformly valid in time. Finally, full numerical solutions of the governing equations are compared with solutions obtained using the various <span class="hlt">variational</span> approximations, with the best agreement achieved with modulation theory due to its ability to include both mass and angular momentum losses to shed diffractive radiation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/AD1039573','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/AD1039573"><span>Develop <span class="hlt">Accurate</span> Methods for Characterizing And Quantifying Cohesive Sediment Erosion Under Combined Current <span class="hlt">Wave</span> Conditions: Project ER 1497</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2017-09-01</p> <p>ER D C/ CH L TR -1 7- 15 Strategic Environmental Research and Development Program Develop <span class="hlt">Accurate</span> Methods for Characterizing and...current environments. This research will provide more <span class="hlt">accurate</span> methods for assessing contaminated sediment stability for many DoD and Environmental...47.88026 pascals yards 0.9144 meters ERDC/CHL TR-17-15 xi Executive Summary Objective The proposed research goal is to develop laboratory methods</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_25 --> <div class="footer-extlink text-muted" style="margin-bottom:1rem; text-align:center;">Some links on this page may take you to non-federal websites. 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