Electromagnetic scattering and depolarization across rough surfaces: Full wave analysis
NASA Astrophysics Data System (ADS)
Bahar, Ezekiel; Huang, Guorong; Lee, Bom Son
1995-05-01
Full wave solutions are derived for vertically and horizontally polarized waves diffusely scattered across an interface that is two-dimensionally rough separating two different propagating media. Since the normal to the rough surface is not restricted to the reference plane of incidence, the waves are depolarized upon scattering; and the single scattered radiation fields are expressed as integrals of a surface element transmission scattering matrix that also accounts for coupling between the vertically and horizontally polarized waves. The integrations are over the rough surface area as well as the complete two-dimensional wave spectra of the radiation fields. The full wave solutions satisfy the duality and reciprocity relationships in electromagnetic theory, and the surface element scattering matrix is invariant to coordinate transformations. It is shown that in the high-frequency limit the full wave solutions reduce to the physical optics solutions, while in the low-frequency limit (for small mean square heights and slopes) the full wave solutions reduce to Rice's (1951) small perturbation solutions. Thus, the full wave solution accounts for specular point scattering as well as diffuse, Bragg-type scattering in a unified, self-consistent manner. It is therefore not necessary to use hybrid, perturbation and physical optics approaches (based on two-scale models of composite surfaces with large and small roughness scales) to determine the like- and cross-polarized fields scattered across the rough surface.
NASA Astrophysics Data System (ADS)
Yang, Si-Tong; Wei, Jiu-Chuan; Cheng, Jiu-Long; Shi, Long-Qing; Wen, Zhi-Jie
2016-12-01
Currently, numerical simulations of seismic channel waves for the advance detection of geological structures in coal mine roadways focus mainly on modeling twodimensional wave fields and therefore cannot accurately simulate three-dimensional (3-D) full-wave fields or seismic records in a full-space observation system. In this study, we use the first-order velocity-stress staggered-grid finite difference algorithm to simulate 3-D full-wave fields with P-wave sources in front of coal mine roadways. We determine the three components of velocity V x, V y, and V z for the same node in 3-D staggered-grid finite difference models by calculating the average value of V y, and V z of the nodes around the same node. We ascertain the wave patterns and their propagation characteristics in both symmetrical and asymmetric coal mine roadway models. Our simulation results indicate that the Rayleigh channel wave is stronger than the Love channel wave in front of the roadway face. The reflected Rayleigh waves from the roadway face are concentrated in the coal seam, release less energy to the roof and floor, and propagate for a longer distance. There are surface waves and refraction head waves around the roadway. In the seismic records, the Rayleigh wave energy is stronger than that of the Love channel wave along coal walls of the roadway, and the interference of the head waves and surface waves with the Rayleigh channel wave is weaker than with the Love channel wave. It is thus difficult to identify the Love channel wave in the seismic records. Increasing the depth of the receivers in the coal walls can effectively weaken the interference of surface waves with the Rayleigh channel wave, but cannot weaken the interference of surface waves with the Love channel wave. Our research results also suggest that the Love channel wave, which is often used to detect geological structures in coal mine stopes, is not suitable for detecting geological structures in front of coal mine roadways
Scattering and Depolarization of Electromagnetic Waves--Full Wave Solutions.
1984-01-01
Analysis," Proceedings of the International Union of Radio Science URSI Conference at Ciudad Universitaria , Madrid, August 1983, in press. . . 13...rough land and seat3 J. The full wave approach was also used to determine the scattering and depolarization of radio waves in irregular spheroidal struc...Full Wave Solutions," Radio Science, Vol. 17, No. 5, September-October 1982, pp. 1055-1066. 4. "Scattering and Depolarization by Rough Surfaces: Full
Portable tremor monitor system for real-time full-wave monitoring and analysis
NASA Astrophysics Data System (ADS)
Yang, Meng-Hsiang; Sheu, Yung-Hoh; Shih, Yuan-Hsing; Young, M. S.
2003-03-01
Tremors, which occur anytime during the daily 24 h cycle, may be missed if monitoring is performed on a short-term basis. Improving this situation requires long-term ambulatory recording capability. There are traditionally two methods for long-term recording of tremors: one is the analog recorder, which is both heavy and inconvenient when transferring data to a PC system; the other is the Actigraph, in which only movement counts are recorded, such data being incomplete. Thus, for long-term and continuous tremor monitoring, this study presents a wrist-worn portable system that can save an entire 24 h tremor wave form in an expansible compact flash memory card. With a rechargeable battery and USB interface, the system has two modes: (1) the monitoring mode while connected to a host computer allows confirmation of system operation, calibration of accelerometers, and immediate display of data on a PC screen and (2) the collecting mode saves data during daily activity on the compact flash memory card within the device. After collection, data are accessed to a host computer for processing. Analysis based on complete tremor wave form including tremor frequency and intensity of 24 h data is expected to allow improved understanding and treatment of tremors.
Full wave analysis and miniaturization of microstrip antenna on ferrimagnetics substrates
NASA Astrophysics Data System (ADS)
Lavor, Otávio Paulino; Fernandes, Humberto Cesar Chaves
2016-02-01
This paper presents the miniaturization of the microstrip antenna on ferrimagnetic substrate for operate at a frequency of 2.5 GHz, where the full wave method Transverse Transmission Line-TTL is used it for obtain resonance frequency. For validate this method in these substrates, the results as function of DC magnetic field are shown. When the field is 132.6 AT/m, the value of reference is 151.7 MHz and the value of TTL is 151.3 MHz. The dimensions are obtained for the frequency of 2.5 GHz and a comparison is done with ferrites and conventional substrate, showing a reduction in volume of the antenna of 2808.96 mm3 for 0.39 mm3 when the ferrites are used.
Lee, L.H.; Lyons, W.G.; Orlando, T.P.; Ali, S.M. . Dept. of Electrical Engineering and Computer Science); Lyons, W.G. . Lincoln Lab.); Withers, R.S. )
1993-12-01
A computationally efficient full-wave technique is developed to analyze single and coupled superconducting microstrip lines on anisotropic substrates. The optic axis of the dielectric is in the plane of the substrate at an arbitrary angle with respect to the propagation direction. A dyadic Green's function for layered, anisotropic media is used to formulate an integral equation for the current in the strips. To increase the efficiency of the method, the superconducting strips are replaced by equivalent surface impedances which account for the loss and kinetic inductance of the superconductors. The validity of this equivalent surface impedance (ESI) approach is verified by comparing the calculated complex propagation constant and characteristic impedance for superconducting microstrip lines on an isotropic substrate to measured results, and to numerical results by the more rigorous volume-integral equation method. The results calculated using the ESI approach for perfectly conducting coupled lines on an anisotropic substrate agree with the results by the finite-difference time-domain method. This efficient ESI technique is then used to study the effects of the optic axis orientation and the strip width on the characteristics of single and coupled superconducting microstrip lines on M-plane sapphire. The effects of the line separation and operating temperature on the coupled lines are also investigated.
NASA Technical Reports Server (NTRS)
2004-01-01
This image shows a close-up view of a density wave in Saturn's A ring. It was taken by the narrow angle camera on the Cassini spacecraft after successful entry into Saturn's orbit. The view shows the dark, or unlit, side of the rings.
Full wave-field reflection coefficient inversion.
Dettmer, Jan; Dosso, Stan E; Holland, Charles W
2007-12-01
This paper develops a Bayesian inversion for recovering multilayer geoacoustic (velocity, density, attenuation) profiles from a full wave-field (spherical-wave) seabed reflection response. The reflection data originate from acoustic time series windowed for a single bottom interaction, which are processed to yield reflection coefficient data as a function of frequency and angle. Replica data for inversion are computed using a wave number-integration model to calculate the full complex acoustic pressure field, which is processed to produce a commensurate seabed response function. To address the high computational cost of calculating short range acoustic fields, the inversion algorithms are parallelized and frequency averaging is replaced by range averaging in the forward model. The posterior probability density is interpreted in terms of optimal parameter estimates, marginal distributions, and credibility intervals. Inversion results for the full wave-field seabed response are compared to those obtained using plane-wave reflection coefficients. A realistic synthetic study indicates that the plane-wave assumption can fail, producing erroneous results with misleading uncertainty bounds, whereas excellent results are obtained with the full-wave reflection inversion.
Du Chaohai; Liu Pukun
2010-03-15
The stability of the millimeter-wave gyrotron-traveling-wave-tube (gyro-TWT) amplifier can be effectively improved via controlling the propagation characteristics of the operating modes using lossy dielectric-lined (DL) waveguide. Self-consistent nonlinear theory of the electron cyclotron maser (ECM) interaction in lossy DL circuit is developed based on a full-wave study of the propagation characteristics of the DL waveguide. This nonlinear theory fully takes into consideration the waveguide structure and the lossy dielectric characteristics. It is capable of accurately calculating the ECM instability between a cyclotron harmonic and a circular polarized mode, and effectively predicting the nonlinear stability of the DL waveguide-based gyro-TWT. Systematic investigation of a Ka-band TE{sub 01} mode DL waveguide-based gyro-TWT is carried out, and numerical calculation reveals a series of interesting results. This work provides a basic theoretical tool for further exploring the application of the lossy DL waveguide in millimeter-wave gyro-TWTs.
Source Estimation by Full Wave Form Inversion
Sjögreen, Björn; Petersson, N. Anders
2013-08-07
Given time-dependent ground motion recordings at a number of receiver stations, we solve the inverse problem for estimating the parameters of the seismic source. The source is modeled as a point moment tensor source, characterized by its location, moment tensor components, the start time, and frequency parameter (rise time) of its source time function. In total, there are 11 unknown parameters. We use a non-linear conjugate gradient algorithm to minimize the full waveform misfit between observed and computed ground motions at the receiver stations. An important underlying assumption of the minimization problem is that the wave propagation is accurately described by the elastic wave equation in a heterogeneous isotropic material. We use a fourth order accurate finite difference method, developed in [12], to evolve the waves forwards in time. The adjoint wave equation corresponding to the discretized elastic wave equation is used to compute the gradient of the misfit, which is needed by the non-linear conjugated minimization algorithm. A new source point moment source discretization is derived that guarantees that the Hessian of the misfit is a continuous function of the source location. An efficient approach for calculating the Hessian is also presented. We show how the Hessian can be used to scale the problem to improve the convergence of the non-linear conjugated gradient algorithm. Numerical experiments are presented for estimating the source parameters from synthetic data in a layer over half-space problem (LOH.1), illustrating rapid convergence of the proposed approach.
Full spectrum millimeter-wave modulation.
Macario, Julien; Yao, Peng; Shi, Shouyuan; Zablocki, Alicia; Harrity, Charles; Martin, Richard D; Schuetz, Christopher A; Prather, Dennis W
2012-10-08
In recent years, the development of new lithium niobate electro-optic modulator designs and material processing techniques have contributed to support the increasing need for faster optical networks by considerably extending the operational bandwidth of modulators. In an effort to provide higher bandwidths for future generations of networks, we have developed a lithium niobate electro-optic phase modulator based on a coplanar waveguide ridged structure that operates up to 300 GHz. By thinning the lithium niobate substrate down to less than 39 µm, we are able to eliminate substrate modes and observe optical sidebands over the full millimeter-wave spectrum.
Lu, Z. X.
2015-05-15
The complex mixed Wentzel–Kramers–Brillouin (WKB)-full-wave approach is applied to the 2D mode structure analysis of ion temperature gradient/collisionless trapped electron mode drift waves in tokamak plasmas. The parallel mode structure is calculated with the full-wave approach, while the radial envelope is calculated with the complex WKB method. The tilting of the global mode structure along radius is demonstrated analytically. The effects of the phase and amplitude variation of the radial envelope on the parallel mode structure are included in terms of a complex radial wave vector in the parallel mode equation. It is shown that the radial equilibrium non-uniformity leads to the asymmetry of the parallel mode structure not only in configuration space but also in spectrum space. The mixed approach provides a practical way to analyze the asymmetric component of the global mode structure due to radial equilibrium non-uniformity.
Full-Wave Modeling of EMIC Waves in the Earth's magnetosphere
NASA Astrophysics Data System (ADS)
Kim, E. H.; Johnson, J.; Keller, S.
2015-12-01
Electromagnetic (EMIC) waves are known to be excited by the cyclotron instability associated with hot and anisotropic ion distributions in the equatorial region of the magnetosphere. One of the significant scientific issues concerning EMIC waves is to understand how these waves are detected at the ground. In order to solve this puzzle, it is necessary to understand the propagation characteristics of the field-aligned EMIC waves, which include polarization reversal, cutoff, resonance, and mode coupling between different wave modes, in dipolar magnetic field. However, the inability of ray-tracing to adequately describe wave propagation near the crossover cutoff-resonance frequencies in multi-ion plasma is a one of the reasons why the scientific questions remain unsolved. Using a recently developed 2D full-wave code that solves the full wave equations in global magnetospheric geometry, we demonstrate how EMIC waves propagate to higher magnetic latitude in an electron-proton-He+ plasma. We find that polarization reversal occurs at the crossover frequency from left-hand (LH) to right-hand (RH) polarization and the RH EMIC waves can either propagate to the inner magnetosphere or reflect to the outer magnetosphere at the Buchsbaum resonance location. We also clearly found mode-coupling from guided LH EMIC waves to unguided RH or LH waves (i.e., fast mode) occurs at the crossover location, which is consistent with previous 1D full-wave analysis.
NASA Technical Reports Server (NTRS)
Lansing, Faiza S.; Rascoe, Daniel L.
1993-01-01
This paper presents a modified Finite-Difference Time-Domain (FDTD) technique using a generalized conformed orthogonal grid. The use of the Conformed Orthogonal Grid, Finite Difference Time Domain (GFDTD) enables the designer to match all the circuit dimensions, hence eliminating a major source o error in the analysis.
Full-wave and half-wave rectification in second-order motion perception
NASA Technical Reports Server (NTRS)
Solomon, J. A.; Sperling, G.
1994-01-01
Microbalanced stimuli are dynamic displays which do not stimulate motion mechanisms that apply standard (Fourier-energy or autocorrelational) motion analysis directly to the visual signal. In order to extract motion information from microbalanced stimuli, Chubb and Sperling [(1988) Journal of the Optical Society of America, 5, 1986-2006] proposed that the human visual system performs a rectifying transformation on the visual signal prior to standard motion analysis. The current research employs two novel types of microbalanced stimuli: half-wave stimuli preserve motion information following half-wave rectification (with a threshold) but lose motion information following full-wave rectification; full-wave stimuli preserve motion information following full-wave rectification but lose motion information following half-wave rectification. Additionally, Fourier stimuli, ordinary square-wave gratings, were used to stimulate standard motion mechanisms. Psychometric functions (direction discrimination vs stimulus contrast) were obtained for each type of stimulus when presented alone, and when masked by each of the other stimuli (presented as moving masks and also as nonmoving, counterphase-flickering masks). RESULTS: given sufficient contrast, all three types of stimulus convey motion. However, only one-third of the population can perceive the motion of the half-wave stimulus. Observers are able to process the motion information contained in the Fourier stimulus slightly more efficiently than the information in the full-wave stimulus but are much less efficient in processing half-wave motion information. Moving masks are more effective than counterphase masks at hampering direction discrimination, indicating that some of the masking effect is interference between motion mechanisms, and some occurs at earlier stages. When either full-wave and Fourier or half-wave and Fourier gratings are presented simultaneously, there is a wide range of relative contrasts within which the
Full-Wave Radio Characterization of Ionospheric Modification at HAARP
2015-07-26
V. Belyey. The spatial features of the up- and downshifted maxima in stimulated electromagnetic emissions, Advances in Space Research, (05 2012...Full-Wave Radio Characterization of Ionospheric Modification at HAARP We have studied electrostatic and electromagnetic turbulence stimulated by...frequency, radio, full wave, plasma waves, plasma instabilites, remote sensing, electromagnetic emissions, antenna, radio imaging, descending layer REPORT
Full Wave Modeling of Helicon Operation in Proto-MPEX
NASA Astrophysics Data System (ADS)
Piotrowicz, Pawel; Caneses, Juan; David, Green; Lau, Cornwall; Caughman, John; Goulding, Richard; Ruzic, David; Proto-MPEX Team
2016-10-01
An improved ``high density mode'' of operation of the helicon plasma source on Proto-MPEX has been observed recently. The high density mode is characterized by an increase in on-axis electron density (>5e19 m-3) and a flat electron temperature (2 - 3 eV) profile during a helicon pulse. Presently, this transition has only been observed when deuterium gas is puffed downstream of the helicon antenna and the delivered RF power exceeds 110 kW. Establishing plasma densities and magnetic field strengths under the antenna that support a stable resonant helicon mode are believed to be the reason for the improved mode of operation. A full wave model of the helicon antenna has been made using finite element analysis software, COMSOL Multiphysics. This model is used to investigate the wave fields produced by the helicon antenna before and after the high density transition occurs. The investigation of the wave fields will be used in identifying the experimental conditions that are necessary for the high density mode transition and the resonant helicon mode responsible for the transition. Simulation results will be compared to radial B-dot probe measurements at multiple axial locations. U.S. D.O.E. contract DE-AC05-00OR22725.
Anton, Luis; MartI, Jose M; Ibanez, Jose M; Aloy, Miguel A.; Mimica, Petar; Miralles, Juan A.
2010-05-01
We obtain renormalized sets of right and left eigenvectors of the flux vector Jacobians of the relativistic MHD equations, which are regular and span a complete basis in any physical state including degenerate ones. The renormalization procedure relies on the characterization of the degeneracy types in terms of the normal and tangential components of the magnetic field to the wave front in the fluid rest frame. Proper expressions of the renormalized eigenvectors in conserved variables are obtained through the corresponding matrix transformations. Our work completes previous analysis that present different sets of right eigenvectors for non-degenerate and degenerate states, and can be seen as a relativistic generalization of earlier work performed in classical MHD. Based on the full wave decomposition (FWD) provided by the renormalized set of eigenvectors in conserved variables, we have also developed a linearized (Roe-type) Riemann solver. Extensive testing against one- and two-dimensional standard numerical problems allows us to conclude that our solver is very robust. When compared with a family of simpler solvers that avoid the knowledge of the full characteristic structure of the equations in the computation of the numerical fluxes, our solver turns out to be less diffusive than HLL and HLLC, and comparable in accuracy to the HLLD solver. The amount of operations needed by the FWD solver makes it less efficient computationally than those of the HLL family in one-dimensional problems. However, its relative efficiency increases in multidimensional simulations.
NASA Astrophysics Data System (ADS)
Antón, Luis; Miralles, Juan A.; Martí, José M.; Ibáñez, José M.; Aloy, Miguel A.; Mimica, Petar
2010-05-01
We obtain renormalized sets of right and left eigenvectors of the flux vector Jacobians of the relativistic MHD equations, which are regular and span a complete basis in any physical state including degenerate ones. The renormalization procedure relies on the characterization of the degeneracy types in terms of the normal and tangential components of the magnetic field to the wave front in the fluid rest frame. Proper expressions of the renormalized eigenvectors in conserved variables are obtained through the corresponding matrix transformations. Our work completes previous analysis that present different sets of right eigenvectors for non-degenerate and degenerate states, and can be seen as a relativistic generalization of earlier work performed in classical MHD. Based on the full wave decomposition (FWD) provided by the renormalized set of eigenvectors in conserved variables, we have also developed a linearized (Roe-type) Riemann solver. Extensive testing against one- and two-dimensional standard numerical problems allows us to conclude that our solver is very robust. When compared with a family of simpler solvers that avoid the knowledge of the full characteristic structure of the equations in the computation of the numerical fluxes, our solver turns out to be less diffusive than HLL and HLLC, and comparable in accuracy to the HLLD solver. The amount of operations needed by the FWD solver makes it less efficient computationally than those of the HLL family in one-dimensional problems. However, its relative efficiency increases in multidimensional simulations.
Pingenot, J; Rieben, R; White, D
2004-12-06
We present a computational study of signal propagation and attenuation of a 200 MHz dipole antenna in a cave environment. The cave is modeled as a straight and lossy random rough wall. To simulate a broad frequency band, the full wave Maxwell equations are solved directly in the time domain via a high order vector finite element discretization using the massively parallel CEM code EMSolve. The simulation is performed for a series of random meshes in order to generate statistical data for the propagation and attenuation properties of the cave environment. Results for the power spectral density and phase of the electric field vector components are presented and discussed.
3D Full-Wave Simulations of Reflectometry
Valeo, E. J.; Kramer, G. J.; Nazikian, R.
2009-11-26
The characterization of fluctuation amplitudes, spatial correlation lengths, and wave vectors through measurement of the correlation properties of reflected microwave diagnostic signals depends on a quantitative knowledge of propagation in toroidal, magnetized plasma. The disparity between the radiation wavelength (mm) and the plasma size makes full wave computations challenging. We extend a two dimensional model which computes propagation in a poloidal plane to include toroidal variation. The model reduces the computational burden compared to that of solving the full-wave equation everywhere-but retains both diffraction and refraction-by merging a description appropriate to the under dense plasma (paraxial) with the required full-wave description near the reflection layer. Initial results for ITER-like profiles demonstrate the utility of the tool as an aid in specifying antenna positioning and setting sensitivity requirements.
Full wave effects on the lower hybrid wave spectrum and driven current profile in tokamak plasmas
Shiraiwa, S.; Ko, J.; Meneghini, O.; Parker, R.; Schmidt, A. E.; Greenwald, M.; Hubbard, A. E.; Hughes, J.; Ma, Y.; Podpaly, Y.; Rice, J. E.; Wallace, G.; Wolfe, S. M.; C-Mod Group, Alcator; Scott, S.; Wilson, J. R.
2011-08-15
A numerical modeling of current profile modification by lower hybrid current drive (LHCD) using a fullwave/Fokker-Planck simulation code is presented. A MHD stable LHCD discharge on Alcator C-Mod was analyzed, and the current profile from full wave simulations was found to show better agreement with the experiment than a ray-tracing code. Comparison of full wave and ray-tracing simulation shows that, although ray-tracing can reproduce the stochastic wave spectrum broadening, the full wave calculation predicts even wider spectrum broadening, and the wave spectrum fills all of the kinematically allowed domain. This is the first demonstration of LHCD current profile modeling using a full wave simulation code in a multi-pass absorption regime, showing the clear impact of full wave effects on the LHCD driven current profile.
Pingenot, J; Rieben, R; White, D; Dudley, D
2005-10-31
We present a computational study of signal propagation and attenuation of a 200 MHz planar loop antenna in a cave environment. The cave is modeled as a straight and lossy random rough wall. To simulate a broad frequency band, the full wave Maxwell equations are solved directly in the time domain via a high order vector finite element discretization using the massively parallel CEM code EMSolve. The numerical technique is first verified against theoretical results for a planar loop antenna in a smooth lossy cave. The simulation is then performed for a series of random rough surface meshes in order to generate statistical data for the propagation and attenuation properties of the antenna in a cave environment. Results for the mean and variance of the power spectral density of the electric field are presented and discussed.
Reactive power in the full Gaussian light wave.
Seshadri, S R
2009-11-01
The electric current sources that are required for the excitation of the fundamental Gaussian beam and the corresponding full Gaussian light wave are determined. The current sources are situated on the secondary source plane that forms the boundary between the two half-spaces in which the waves are launched. The electromagnetic fields and the complex power generated by the current sources are evaluated. For the fundamental Gaussian beam, the reactive power vanishes, and the normalization is chosen such that the real power is 2 W. The various full Gaussian waves are identified by the length parameter b(t) that lies in the range 0 < or = b(t) < or = b, where b is the Rayleigh distance. The other parameters are the wavenumber k, the free-space wavelength lambda, and the beam waist w0 at the input plane. The dependence of the real power of the full Gaussian light wave on b(t)/b and w0/lambda is examined. For a specified w0/lambda, the reactive power, which can be positive or negative, increases as b(t)/b is increased from 0 to 1 and becomes infinite for b(t)/b=1. For a specified b(t)/b, the reactive power approaches zero as kw0 is increased and reaches the limiting value of zero of the paraxial beam.
Benchmarking ICRF Full-wave Solvers for ITER
R. V. Budny, L. Berry, R. Bilato, P. Bonoli, M. Brambilla, R. J. Dumont, A. Fukuyama, R. Harvey, E. F. Jaeger, K. Indireshkumar, E. Lerche, D. McCune, C. K. Phillips, V. Vdovin, J. Wright, and members of the ITPA-IOS
2011-01-06
Abstract Benchmarking of full-wave solvers for ICRF simulations is performed using plasma profiles and equilibria obtained from integrated self-consistent modeling predictions of four ITER plasmas. One is for a high performance baseline (5.3 T, 15 MA) DT H-mode. The others are for half-field, half-current plasmas of interest for the pre-activation phase with bulk plasma ion species being either hydrogen or He4. The predicted profiles are used by six full-wave solver groups to simulate the ICRF electromagnetic fields and heating, and by three of these groups to simulate the current-drive. Approximate agreement is achieved for the predicted heating power for the DT and He4 cases. Factor of two disagreements are found for the cases with second harmonic He3 heating in bulk H cases. Approximate agreement is achieved simulating the ICRF current drive.
Full-wave modeling of EMIC waves near the He+ gyrofrequency
Kim, Eun -Hwa; Johnson, Jay R.
2016-01-06
Electromagnetic ion cyclotron (EMIC) waves are known to be excited by the cyclotron instability associated with hot and anisotropic ion distributions in the equatorial region of the magnetosphere and are thought to play a key role in radiation belt losses. Although detection of these waves at the ground can provide a global view of the EMIC wave environment, it is not clear what signatures, if any, would be expected. One of the significant scientific issues concerning EMIC waves is to understand how these waves are detected at the ground. In order to solve this puzzle, it is necessary to understandmore » the propagation characteristics of the field-aligned EMIC waves, which include polarization reversal, cutoff, resonance, and mode coupling between different wave modes, in a dipolar magnetic field. However, the inability of ray tracing to adequately describe wave propagation near the crossover cutoff-resonance frequencies in multi-ion plasmas is one of reasons why these scientific questions remain unsolved. Using a recently developed 2-D full-wave code that solves the full-wave equations in global magnetospheric geometry, we demonstrate how EMIC waves propagate from the equatorial region to higher magnetic latitude in an electron-proton-He+ plasma. We find that polarization reversal occurs at the crossover frequency from left-hand polarization (LHP) to right-hand (RHP) polarization and such RHP EMIC waves can either propagate to the inner magnetosphere or reflect to the outer magnetosphere at the Buchsbaum resonance location. Lastly, we also find that mode coupling from guided LHP EMIC waves to unguided RHP or LHP waves (i.e., fast mode) occurs.« less
Full-wave modeling of EMIC waves near the He^{+} gyrofrequency
Kim, Eun -Hwa; Johnson, Jay R.
2016-01-06
Electromagnetic ion cyclotron (EMIC) waves are known to be excited by the cyclotron instability associated with hot and anisotropic ion distributions in the equatorial region of the magnetosphere and are thought to play a key role in radiation belt losses. Although detection of these waves at the ground can provide a global view of the EMIC wave environment, it is not clear what signatures, if any, would be expected. One of the significant scientific issues concerning EMIC waves is to understand how these waves are detected at the ground. In order to solve this puzzle, it is necessary to understand the propagation characteristics of the field-aligned EMIC waves, which include polarization reversal, cutoff, resonance, and mode coupling between different wave modes, in a dipolar magnetic field. However, the inability of ray tracing to adequately describe wave propagation near the crossover cutoff-resonance frequencies in multi-ion plasmas is one of reasons why these scientific questions remain unsolved. Using a recently developed 2-D full-wave code that solves the full-wave equations in global magnetospheric geometry, we demonstrate how EMIC waves propagate from the equatorial region to higher magnetic latitude in an electron-proton-He+ plasma. We find that polarization reversal occurs at the crossover frequency from left-hand polarization (LHP) to right-hand (RHP) polarization and such RHP EMIC waves can either propagate to the inner magnetosphere or reflect to the outer magnetosphere at the Buchsbaum resonance location. Lastly, we also find that mode coupling from guided LHP EMIC waves to unguided RHP or LHP waves (i.e., fast mode) occurs.
A full-wave Helmholtz model for continuous-wave ultrasound transmission.
Huttunen, Tomi; Malinen, Matti; Kaipio, Jari P; White, Phillip Jason; Hynynen, Kullervo
2005-03-01
A full-wave Helmholtz model of continuous-wave (CW) ultrasound fields may offer several attractive features over widely used partial-wave approximations. For example, many full-wave 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-wave 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 wave simulations in 3D geometries which reach over tens of wavelengths. The aim of this study is to investigate the feasibility of a full-wave solution of the 3D Helmholtz equation for modeling of continuous-wave ultrasound fields in an inhomogeneous medium. The numerical approximation of the Helmholtz equation is computed using the ultraweak variational 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.
Guided Wave Tomography Based on Full-Waveform Inversion.
Rao, Jing; Ratassepp, Madis; Fan, Zheng
2016-02-29
In this paper, a guided wave tomography method based on Full Waveform Inversion (FWI) is developed for accurate and high resolu- tion reconstruction of the remaining wall thickness in isotropic plates. The forward model is computed in the frequency domain by solving a full-wave equation in a two-dimensional acoustic model, accounting for higher order eects such as diractions and multiple scattering. Both numerical simulations and experiments were carried out to obtain the signals of a dispersive guided mode propagating through defects. The inversion was based on local optimization of a waveform mist func- tion between modeled and measured data, and was applied iteratively to discrete frequency components from low to high frequencies. The resulting wave velocity maps were then converted to thickness maps by the dispersion characteristics of selected guided modes. The results suggest that the FWI method is capable to reconstruct the thickness map of a irregularly shaped defect accurately on a 10 mm thick plate with the thickness error within 0.5 mm.
Direct Calculations of Current Drive with a Full Wave Code
NASA Astrophysics Data System (ADS)
Wright, John C.; Phillips, Cynthia K.
1997-11-01
We have developed a current drive package that evaluates the current driven by fast magnetosonic waves in arbitrary flux geometry. An expression for the quasilinear flux has been derived which accounts for coupling between modes in the spectrum of waves launched from the antenna. The field amplitudes are calculated in the full wave code, FISIC, and the current response function, \\chi, also known as the Spitzer function, is determined with Charles Karney's Fokker-Planck code, adj.f. Both codes have been modified to incorporate the same numerical equilibria. To model the effects of a trapped particle population, the bounce averaged equations for current and power are used, and the bounce averaged flux is calculated. The computer model is benchmarked against the homogenous equations for a high aspect ratio case in which the expected agreement is confirmed. Results from cases for TFTR, NSTX and CDX-U are contrasted with the predictions of the Ehst-Karney parameterization of current drive for circular equilibria. For theoretical background, please see the authors' archive of papers. (http://w3.pppl.gov/ ~jwright/Publications)
Kinetic full wave analyses of O-X-B mode conversion of EC waves in tokamak plasmas
NASA Astrophysics Data System (ADS)
Fukuyama, Atsushi; Khan, Shabbir Ahmad; Igami, Hiroe; Idei, Hiroshi
2016-10-01
For heating and current drive in a high-density plasma of tokamak, especially spherical tokamak, the use of electron Bernstein waves and the O-X-B mode conversion were proposed and experimental observations have been reported. In order to evaluate the power deposition profile and the current drive efficiency, kinetic full wave analysis using an integral form of dielectric tensor has been developed. The incident angle dependence of wave structure and O-X-B mode conversion efficiency is examined using one-dimensional analysis in the major radius direction. Two-dimensional analyses on the horizontal plane and the poloidal plane are also conducted, and the wave structure and the power deposition profile are compared with those of previous analyses using ray tracing method and cold plasma approximation. This work is supported by JSPS KAKENHI Grant Number JP26630471.
Beamforming Based Full-Duplex for Millimeter-Wave Communication.
Liu, Xiao; Xiao, Zhenyu; Bai, Lin; Choi, Jinho; Xia, Pengfei; Xia, Xiang-Gen
2016-07-21
In this paper, we study beamforming based full-duplex (FD) systems in millimeter-wave (mmWave) communications. A joint transmission and reception (Tx/Rx) beamforming problem is formulated to maximize the achievable rate by mitigating self-interference (SI). Since the optimal solution is difficult to find due to the non-convexity of the objective function, suboptimal schemes are proposed in this paper. A low-complexity algorithm, which iteratively maximizes signal power while suppressing SI, is proposed and its convergence is proven. Moreover, two closed-form solutions, which do not require iterations, are also derived under minimum-mean-square-error (MMSE), zero-forcing (ZF), and maximum-ratio transmission (MRT) criteria. Performance evaluations show that the proposed iterative scheme converges fast (within only two iterations on average) and approaches an upper-bound performance, while the two closed-form solutions also achieve appealing performances, although there are noticeable differences from the upper bound depending on channel conditions. Interestingly, these three schemes show different robustness against the geometry of Tx/Rx antenna arrays and channel estimation errors.
Beamforming Based Full-Duplex for Millimeter-Wave Communication
Liu, Xiao; Xiao, Zhenyu; Bai, Lin; Choi, Jinho; Xia, Pengfei; Xia, Xiang-Gen
2016-01-01
In this paper, we study beamforming based full-duplex (FD) systems in millimeter-wave (mmWave) communications. A joint transmission and reception (Tx/Rx) beamforming problem is formulated to maximize the achievable rate by mitigating self-interference (SI). Since the optimal solution is difficult to find due to the non-convexity of the objective function, suboptimal schemes are proposed in this paper. A low-complexity algorithm, which iteratively maximizes signal power while suppressing SI, is proposed and its convergence is proven. Moreover, two closed-form solutions, which do not require iterations, are also derived under minimum-mean-square-error (MMSE), zero-forcing (ZF), and maximum-ratio transmission (MRT) criteria. Performance evaluations show that the proposed iterative scheme converges fast (within only two iterations on average) and approaches an upper-bound performance, while the two closed-form solutions also achieve appealing performances, although there are noticeable differences from the upper bound depending on channel conditions. Interestingly, these three schemes show different robustness against the geometry of Tx/Rx antenna arrays and channel estimation errors. PMID:27455256
Full wave simulations of microwave interactions with turbulence
NASA Astrophysics Data System (ADS)
Thomas, Matthew; Vann, Roddy; Leddy, Jarrod; Koehn, Alf; University of York; IPP Garching Collaboration; University of York; Culham Microwave Group Team
2016-10-01
The interaction between electromagnetic radiation and plasma perturbations in the case that the radiation wavelength is comparable to the size of the perturbations is not a fully-understood problem. Yet the use of microwaves in magnetic confinement fusion plasmas is widespread for heating, current drive and both passive and active diagnostics, including in regimes for which there exist microwave length-scale plasma perturbations. We present simulation results using the full-wave cold plasma finite difference time domain codes EMIT-3D and IPF-FDMC developed independently at York and Stuttgart, respectively. First we present a novel systematic study of the scattering of microwaves through turbulence: we quantified the relationship between the normalised turbulent correlation length and the scattered power. Additionally we found a quadratic relationship between the scattered wave power and the turbulence amplitude. We go on to present results to model the Doppler back-scattering of a broad microwave beam from a moving turbulent slab. This second problem is particularly important for interpreting data from the Synthetic Aperture Microwave Imaging (SAMI) diagnostic currently installed on NSTX-U.
Full wave propagation modelling in view to integrated ICRH wave coupling/RF sheaths modelling
NASA Astrophysics Data System (ADS)
Jacquot, Jonathan; Bobkov, Volodymyr; Colas, Laurent; Heuraux, Stéphane; Křivská, Alena; Lu, Lingfeng; Noterdaeme, Jean-Marie
2015-12-01
RF sheaths rectification can be the reason for operational limits for Ion Cyclotron Range of Frequencies (ICRF) heating systems via impurity production or excessive heat loads. To simulate this process in realistic geometry, the Self-consistent Sheaths and Waves for Ion Cyclotron Heating (SSWICH) code is a minimal set of coupled equations that computes self-consistently wave propagation and DC plasma biasing. The present version of its wave propagation module only deals with the Slow Wave assumed to be the source of RF sheath oscillations. However the ICRF power coupling to the plasma is due to the fast wave (FW). This paper proposes to replace this one wave equation module by a full wave module in either 2D or 3D as a first step towards integrated modelling of RF sheaths and wave coupling. Since the FW is propagative in the main plasma, Perfectly Matched Layers (PMLs) adapted for plasmas were implemented at the inner side of the simulation domain to absorb outgoing waves and tested numerically with tilted B0 in Cartesian geometry, by either rotating the cold magnetized plasma dielectric tensors in 2D or rotating the coordinate vector basis in 3D. The PML was further formulated in cylindrical coordinates to account for for the toroidal curvature of the plasma. Toroidal curvature itself does not seem to change much the coupling. A detailed 3D geometrical description of Tore Supra and ASDEX Upgrade (AUG) antennas was included in the coupling code. The full antenna structure was introduced, since its toroidal symmetry with respect to the septum plane is broken (FS bars, toroidal phasing, non-symmetrical structure). Reliable convergence has been obtained with the density profile up to the leading edge of antenna limiters. Parallel electric field maps have been obtained as an input for the present version of SSWICH.
Full-wave Electromagnetic Field Simulations of Lower Hybrid Waves in Tokamaks
Wright, J.C.; Bonoli, P. T.; Brambilla, M.; D'Azevedo, E.; Berry, L.A.; Batchelor, D.B.; Jaeger, E.F.; Carter, M.D.; Phillips, C.K.; Okuda, H.; Harvey, R.W.; Myra, J.R.; D'Ippolito, D.A.; Smithe, D.N.
2005-09-26
The most common method for treating wave propagation in tokamaks in the lower hybrid range of frequencies (LHRF) has been toroidal ray tracing, owing to the short wavelengths (relative to the system size) found in this regime. Although this technique provides an accurate description of 2D and 3D plasma inhomogeneity effects on wave propagation, the approach neglects important effects related to focusing, diffraction, and finite extent of the RF launcher. Also, the method breaks down at plasma cutoffs and caustics. Recent adaptation of full-wave electromagnetic field solvers to massively parallel computers has made it possible to accurately resolve wave phenomena in the LHRF. One such solver, the TORIC code, has been modified to simulate LH waves by implementing boundary conditions appropriate for coupling the fast electromagnetic and the slow electrostatic waves in the LHRF. In this frequency regime the plasma conductivity operator can be formulated in the limits of unmagnetized ions and strongly magnetized electrons, resulting in a relatively simple and explicit form. Simulations have been done for parameters typical of the planned LHRF experiments on Alcator C-Mod, demonstrating fully resolved fast and slow LH wave fields using a Maxwellian non-relativistic plasma dielectric. Significant spectral broadening of the injected wave spectrum and focusing of the wave fields have been found, especially at caustic surfaces. Comparisons with toroidal ray tracing have also been done and differences between the approaches have been found, especially for cases where wave caustics form. The possible role of this diffraction-induced spectral broadening in filling the spectral gap in LH heating and current drive will be discussed.
Full-wave multiscale anisotropy tomography in Southern California
NASA Astrophysics Data System (ADS)
Lin, Yu-Pin; Zhao, Li; Hung, Shu-Huei
2014-12-01
Understanding the spatial variation of anisotropy in the upper mantle is important for characterizing the lithospheric deformation and mantle flow dynamics. In this study, we apply a full-wave approach to image the upper-mantle anisotropy in Southern California using 5954 SKS splitting data. Three-dimensional sensitivity kernels combined with a wavelet-based model parameterization are adopted in a multiscale inversion. Spatial resolution lengths are estimated based on a statistical resolution matrix approach, showing a finest resolution length of ~25 km in regions with densely distributed stations. The anisotropic model displays structural fabric in relation to surface geologic features such as the Salton Trough, the Transverse Ranges, and the San Andreas Fault. The depth variation of anisotropy does not suggest a lithosphere-asthenosphere decoupling. At long wavelengths, the fast directions of anisotropy are aligned with the absolute plate motion inside the Pacific and North American plates.
Voltage mode electronically tunable full-wave rectifier
NASA Astrophysics Data System (ADS)
Petrović, Predrag B.; Vesković, Milan; Đukić, Slobodan
2017-01-01
The paper presents a new realization of bipolar full-wave rectifier of input sinusoidal signals, employing one MO-CCCII (multiple output current controlled current conveyor), a zero-crossing detector (ZCD), and one resistor connected to fixed potential. The circuit provides the operating frequency up to 10 MHz with increased linearity and precision in processing of input voltage signal, with a very low harmonic distortion. The errors related to the signal processing and errors bound were investigated and provided in the paper. The PSpice simulations are depicted and agree well with the theoretical anticipation. The maximum power consumption of the converter is approximately 2.83 mW, at ±1.2 V supply voltages.
Full wave simulation of lower hybrid waves in Maxwellian plasma based on the finite element method
Meneghini, O.; Shiraiwa, S.; Parker, R.
2009-09-15
A full wave simulation of the lower-hybrid (LH) wave based on the finite element method is presented. For the LH wave, the most important terms of the dielectric tensor are the cold plasma contribution and the electron Landau damping (ELD) term, which depends only on the component of the wave vector parallel to the background magnetic field. The nonlocal hot plasma ELD effect was expressed as a convolution integral along the magnetic field lines and the resultant integro-differential Helmholtz equation was solved iteratively. The LH wave propagation in a Maxwellian tokamak plasma based on the Alcator C experiment was simulated for electron temperatures in the range of 2.5-10 keV. Comparison with ray tracing simulations showed good agreement when the single pass damping is strong. The advantages of the new approach include a significant reduction of computational requirements compared to full wave spectral methods and seamless treatment of the core, the scrape off layer and the launcher regions.
An assessment of full-wave effects on the propagation and absorption of lower hybrid waves
NASA Astrophysics Data System (ADS)
Wright, John
2008-11-01
Lower hybrid (LH) waves have the attractive property of damping strongly via electron Landau resonance on relatively fast tail electrons. Consequently these waves are well-suited to driving current in the plasma periphery where the electron temperature is lower, making LH current drive (LHCD) a promising technique for off--axis (r/a˜0.60) current profile control in reactor grade plasmas. Established modeling techniques use WKB expansions with non-Maxwellian self-consistent distributions. Higher order WKB expansions have shown some effects on the parallel wavenumber evolution and consequently on the damping due to diffraction [1]. A massively parallel version of the TORIC full-wave electromagnetic field solver valid in the LH range of frequencies has been developed [2] and applied to scenarios at the density and magnetic field characteristic of devices such as Alcator C-Mod and ITER [B0 5 T, ne 1x10^20 m-3]. We find that retaining full wave effects due to diffraction and focusing has a strong effect on the location of wave absorption. Diffraction occurs at caustic surfaces and in resonance cones resulting in a large upshift of the parallel wavenumber and localized power deposition. For some values of density and magnetic field when the waves are fully accessible to the center of the plasma, the full wave description predicts all power being damped at larger radii (r/a ˜ 0.7) in contrast to ray tracing which shows more central power absorption. By incorporating a Fokker-Planck code for self-consistent treatment of the electron distribution and using an synthetic hard X-ray diagnostic we compare the code predictions by both full wave and ray tracing methods with recent Alcator C-Mod experiments. We will compare full-wave and ray tracing for low and high single pass damping regimes. [0pt] [1] G. Pereverzev, Nucl. Fusion 32 1091 (1991). [0pt] [2] J. C. Wright, E. J. Valeo, C. K. Phillips and P. T. Bonoli, Comm. in Comput. Physics 4 545 (2008).
A heterogeneous nonlinear attenuating full-wave model of ultrasound.
Pinton, Gianmarco F; Dahl, Jeremy; Rosenzweig, Stephen; Trahey, Gregg E
2009-03-01
A full-wave equation that describes nonlinear propagation in a heterogeneous attenuating medium is solved numerically with finite differences in the time domain (FDTD). Three-dimensional solutions of the equation are verified with water tank measurements of a commercial diagnostic ultrasound transducer and are shown to be in excellent agreement in terms of the fundamental and harmonic acoustic fields and the power spectrum at the focus. The linear and nonlinear components of the algorithm are also verified independently. In the linear nonattenuating regime solutions match results from Field II, a well established software package used in transducer modeling, to within 0.3 dB. Nonlinear plane wave propagation is shown to closely match results from the Galerkin method up to 4 times the fundamental frequency. In addition to thermoviscous attenuation we present a numerical solution of the relaxation attenuation laws that allows modeling of arbitrary frequency dependent attenuation, such as that observed in tissue. A perfectly matched layer (PML) is implemented at the boundaries with a numerical implementation that allows the PML to be used with high-order discretizations. A -78 dB reduction in the reflected amplitude is demonstrated. The numerical algorithm is used to simulate a diagnostic ultrasound pulse propagating through a histologically measured representation of human abdominal wall with spatial variation in the speed of sound, attenuation, nonlinearity, and density. An ultrasound image is created in silico using the same physical and algorithmic process used in an ultrasound scanner: a series of pulses are transmitted through heterogeneous scattering tissue and the received echoes are used in a delay-and-sum beam-forming algorithm to generate a images. The resulting harmonic image exhibits characteristic improvement in lesion boundary definition and contrast when compared with the fundamental image. We demonstrate a mechanism of harmonic image quality
Full wave simulation of waves in ECRIS plasmas based on the finite element method
Torrisi, G.; Mascali, D.; Neri, L.; Castro, G.; Patti, G.; Celona, L.; Gammino, S.; Ciavola, G.; Di Donato, L.; Sorbello, G.; Isernia, T.
2014-02-12
This paper describes the modeling and the full wave numerical simulation of electromagnetic waves propagation and absorption in an anisotropic magnetized plasma filling the resonant cavity of an electron cyclotron resonance ion source (ECRIS). The model assumes inhomogeneous, dispersive and tensorial constitutive relations. Maxwell's equations are solved by the finite element method (FEM), using the COMSOL Multiphysics{sup ®} suite. All the relevant details have been considered in the model, including the non uniform external magnetostatic field used for plasma confinement, the local electron density profile resulting in the full-3D non uniform magnetized plasma complex dielectric tensor. The more accurate plasma simulations clearly show the importance of cavity effect on wave propagation and the effects of a resonant surface. These studies are the pillars for an improved ECRIS plasma modeling, that is mandatory to optimize the ion source output (beam intensity distribution and charge state, especially). Any new project concerning the advanced ECRIS design will take benefit by an adequate modeling of self-consistent wave absorption simulations.
From supersonic shear wave imaging to full-field optical coherence shear wave elastography
NASA Astrophysics Data System (ADS)
Nahas, Amir; Tanter, Mickaël; Nguyen, Thu-Mai; Chassot, Jean-Marie; Fink, Mathias; Claude Boccara, A.
2013-12-01
Elasticity maps of tissue have proved to be particularly useful in providing complementary contrast to ultrasonic imaging, e.g., for cancer diagnosis at the millimeter scale. Optical coherence tomography (OCT) offers an endogenous contrast based on singly backscattered optical waves. Adding complementary contrast to OCT images by recording elasticity maps could also be valuable in improving OCT-based diagnosis at the microscopic scale. Static elastography has been successfully coupled with full-field OCT (FF-OCT) in order to realize both micrometer-scale sectioning and elasticity maps. Nevertheless, static elastography presents a number of drawbacks, mainly when stiffness quantification is required. Here, we describe the combination of two methods: transient elastography, based on speed measurements of shear waves induced by ultrasonic radiation forces, and FF-OCT, an en face OCT approach using an incoherent light source. The use of an ultrafast ultrasonic scanner and an ultrafast camera working at 10,000 to 30,000 images/s made it possible to follow shear wave propagation with both modalities. As expected, FF-OCT is found to be much more sensitive than ultrafast ultrasound to tiny shear vibrations (a few nanometers and micrometers, respectively). Stiffness assessed in gel phantoms and an ex vivo rat brain by FF-OCT is found to be in good agreement with ultrasound shear wave elastography.
From supersonic shear wave imaging to full-field optical coherence shear wave elastography.
Nahas, Amir; Tanter, Mickaël; Nguyen, Thu-Mai; Chassot, Jean-Marie; Fink, Mathias; Claude Boccara, A
2013-12-01
Elasticity maps of tissue have proved to be particularly useful in providing complementary contrast to ultrasonic imaging, e.g., for cancer diagnosis at the millimeter scale. Optical coherence tomography (OCT) offers an endogenous contrast based on singly backscattered optical waves. Adding complementary contrast to OCT images by recording elasticity maps could also be valuable in improving OCT-based diagnosis at the microscopic scale. Static elastography has been successfully coupled with full-field OCT (FF-OCT) in order to realize both micrometer-scale sectioning and elasticity maps. Nevertheless, static elastography presents a number of drawbacks, mainly when stiffness quantification is required. Here, we describe the combination of two methods: transient elastography, based on speed measurements of shear waves induced by ultrasonic radiation forces, and FF-OCT, an en face OCT approach using an incoherent light source. The use of an ultrafast ultrasonic scanner and an ultrafast camera working at 10,000 to 30,000 images/s made it possible to follow shear wave propagation with both modalities. As expected, FF-OCT is found to be much more sensitive than ultrafast ultrasound to tiny shear vibrations (a few nanometers and micrometers, respectively). Stiffness assessed in gel phantoms and an ex vivo rat brain by FF-OCT is found to be in good agreement with ultrasound shear wave elastography.
Comparison of Monte-Carlo Ion Cyclotron Heating Model with Full-Wave Linear Absorption Model
NASA Astrophysics Data System (ADS)
Choi, M.; Chan, V. S.; Berry, L. A.; Jaeger, E. F.; Green, D.; Bonoli, P.; Wright, J.
2009-05-01
To fully account for the wave-particle interaction physics in ion-cyclotron resonant frequency heating experiments, the 5-D Monte-Carlo code ORBIT-RF is being coupled with the 2-D full wave code AORSA to iteratively evolve ion distribution in x-v space that is used to update the dielectric tensor in AORSA for evaluating the full-wave fields. It is demonstrated that using the full-wave fields from a Maxwellian dielectric tensor in AORSA and confining the resonant ions to their initial orbits in ORBIT-RF, ORBIT-RF largely reproduces the AORSA linear wave absorption profiles for fundamental and higher harmonic ICRF heating. An exception is an observed inward shift of the ORBIT-RF absorption peak for high harmonics near the magnetic-axis compared with that of AORSA, which can be attributed to a finite orbit width effect. Analysis of power absorption in velocity space confirms that significant power is absorbed by energetic particles with their banana tips at resonance locations.
Generalized Full-Information Item Bifactor Analysis
ERIC Educational Resources Information Center
Cai, Li; Yang, Ji Seung; Hansen, Mark
2011-01-01
Full-information item bifactor analysis is an important statistical method in psychological and educational measurement. Current methods are limited to single-group analysis and inflexible in the types of item response models supported. We propose a flexible multiple-group item bifactor analysis framework that supports a variety of…
An assessment of full wave effects on the propagation and absorption of lower hybrid waves
Wright, J. C.; Bonoli, P. T.; Schmidt, A. E.; Phillips, C. K.; Valeo, E. J.; Harvey, R. W.; Brambilla, M. A.
2009-07-15
Lower hybrid (LH) waves ({omega}{sub ci}<<{omega}<<{omega}{sub ce}, where {omega}{sub i,e}{identical_to}Z{sub i,e}eB/m{sub i,e}c) have the attractive property of damping strongly via electron Landau resonance on relatively fast tail electrons and consequently are well-suited to driving current. Established modeling techniques use Wentzel-Kramers-Brillouin (WKB) expansions with self-consistent non-Maxwellian distributions. Higher order WKB expansions have shown some effects on the parallel wave number evolution and consequently on the damping due to diffraction [G. Pereverzev, Nucl. Fusion 32, 1091 (1991)]. A massively parallel version of the TORIC full wave electromagnetic field solver valid in the LH range of frequencies has been developed [J. C. Wright et al., Comm. Comp. Phys. 4, 545 (2008)] and coupled to an electron Fokker-Planck solver CQL3D[R. W. Harvey and M. G. McCoy, in Proceedings of the IAEA Technical Committee Meeting, Montreal, 1992 (IAEA Institute of Physics Publishing, Vienna, 1993), USDOC/NTIS Document No. DE93002962, pp. 489-526] in order to self-consistently evolve nonthermal electron distributions characteristic of LH current drive (LHCD) experiments in devices such as Alcator C-Mod and ITER (B{sub 0}{approx_equal}5 T, n{sub e0}{approx_equal}1x10{sup 20} m{sup -3}). These simulations represent the first ever self-consistent simulations of LHCD utilizing both a full wave and Fokker-Planck calculation in toroidal geometry.
Full spectrum analysis in environmental monitoring.
Reinhardt, Sascha
2014-08-01
In environmental radiation monitoring, the time-variable natural gamma radiation background complicates the nuclide identification and analysis of a gamma spectrum. A full spectrum analysis based on the noise adjusted singular value decomposition method for the description of the time-variable background and adjustment calculations is a possible analysis method, which may provide advantages compared with a peak-based analysis, if applied to a time series of gamma spectra. An analysis example is shown and discussed with a measured time series of gamma spectra obtained from a spectroscopic gamma detector with a NaI(Tl) scintillator as it is used in the environmental radiation monitoring.
NASA Astrophysics Data System (ADS)
Lu, Siliang; He, Qingbo; Zhang, Haibin; Kong, Fanrang
2017-02-01
This study proposes a full-wave signal construction (FSC) strategy for enhancing rotating machine fault diagnosis by exploiting stochastic resonance (SR). The FSC strategy is utilized to transform a half-wave signal (e.g., an envelope signal) into a full-wave one by conducting a Mirror-Cycle-Add (MCA) operation. The constructed full-wave signal evenly modulates the bistable potential and makes the potential tilt back and forth smoothly. This effect provides the equivalent transition probabilities of particle bounce between the two potential wells. A stable SR output signal with better periodicity, which is beneficial to periodic signal detection, can be obtained. In addition, the MCA operation can improve the input signal-to-noise ratio by enhancing the periodic component while attenuating the noise components. These two advantages make the proposed FSCSR method surpass the traditional SR method in fault signal processing. Performance evaluation is conducted by numerical analysis and experimental verification. The proposed MCA-based FSC strategy has the potential to be a universal signal pre-processing technique. Moreover, the proposed FSCSR method can be used in rotating machine fault diagnosis and other areas related to weak signal detection.
Full-wave description of the lower hybrid reflection of whistler waves
Kuzichev, I. V. Shklyar, D. R.
2013-10-15
A quasi-electrostatic whistler wave propagating in the direction of increasing lower hybrid resonance (LHR) frequency experiences reflection from the region in which its frequency becomes lower than the LHR frequency. This phenomenon is usually described in the framework of geometrical optics. For a wave propagating along a magnetospheric trajectory, the LHR reflection frequently takes place in the ionospheric region in which electron-neutral collisions are essential and lead to wave attenuation. In this case, the wave approach to the description of the LHR reflection is most consistent. This work is aimed at developing such an approach. The coefficients of the wave reflection are calculated for different plasma parameters. The relation between the problem under consideration and the problem of exit of whistler-mode waves to the ground is considered.
Ernest Valeo, Jay R. Johnson, Eun-Hwa and Cynthia Phillips
2012-03-13
A wide variety of plasma waves play an important role in the energization and loss of particles in the inner magnetosphere. Our ability to understand and model wave-particle interactions in this region requires improved knowledge of the spatial distribution and properties of these waves as well as improved understanding of how the waves depend on changes in solar wind forcing and/or geomagnetic activity. To this end, we have developed a two-dimensional, finite element code that solves the full wave equations in global magnetospheric geometry. The code describes three-dimensional wave structure including mode conversion when ULF, EMIC, and whistler waves are launched in a two-dimensional axisymmetric background plasma with general magnetic field topology. We illustrate the capabilities of the code by examining the role of plasmaspheric plumes on magnetosonic wave propagation; mode conversion at the ion-ion and Alfven resonances resulting from external, solar wind compressions; and wave structure and mode conversion of electromagnetic ion cyclotron waves launched in the equatorial magnetosphere, which propagate along the magnetic field lines toward the ionosphere. We also discuss advantages of the finite element method for resolving resonant structures, and how the model may be adapted to include nonlocal kinetic effects.
Robust baseline subtraction for ultrasonic full wavefield analysis
NASA Astrophysics Data System (ADS)
Alguri, K. Supreet; Michaels, Jennifer E.; Harley, Joel B.
2017-02-01
Full wavefield analysis is used to study and characterize the interaction between waves and structural damage. Yet, as wavefields are measured and as damage evolves in a structure, environmental and operational variations can significantly affect wave propagation. Several approaches, including time-stretching and optimal baseline selection methods, can reduce variations, but these methods are often limited to specific effects, are ineffective for large environmental variations, or require an impractical number of prior baseline measurements. This paper presents a robust methodology for subtracting wavefields and isolating wave-damage interactions. The method is based on dictionary learning. It is robust to multiple types of environmental and operational variations and requires only one initial baseline. We learn the dictionary, which describes wave propagation for a particular wavefield, based on multiple frequencies of a baseline wavefield. We then use the dictionary and sparse regression to create new baselines for measurements with different environmental and operational conditions. The new baseline is then subtracted from the new wavefield to isolate damage wavefield.
Multichannel analysis of surface waves
Park, C.B.; Miller, R.D.; Xia, J.
1999-01-01
The frequency-dependent properties of Rayleigh-type surface waves can be utilized for imaging and characterizing the shallow subsurface. Most surface-wave analysis relies on the accurate calculation of phase velocities for the horizontally traveling fundamental-mode Rayleigh wave 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-wave velocities determined through inversion of the whole wave field. Among these nonplanar, nonfundamental-mode Rayleigh waves (noise) are body waves, scattered and nonsource-generated surface waves, and higher-mode surface waves. The degree to which each of these types of noise contaminates the dispersion curve and, ultimately, the inverted shear-wave 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-wave 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
NASA Astrophysics Data System (ADS)
Li, C. Y.; Lesselier, D.; Zhong, Y.
2015-07-01
The present work aims at building up a full-wave computational model of electromagnetic nondestructive testing of composite materials produced by stacking up dielectric slabs one over the other. In each such dielectric slab, a periodic array of infinite cylindrical fibers is embedded. Electromagnetic scattering of such a multilayered, fiber-based periodic composite is investigated here for an obliquely incident plane wave, the plane of incidence of which differs from the plane orthogonal to the fibers' axes. Full-wave field representations are given first by multipole and plane wave expansions. Mode matching at boundaries between layers then yields the propagating matrices, which are applied to connect reflection and transmission coefficients of the longitudinal field components. Power reflection and transmission coefficients are obtained from time-averaged Poynting vectors. Numerical experiments with comparisons with known results illustrate the accuracy of the model proposed.
Automatic Processing of Digital Ionograms and Full Wave Solutions for the Profile Inversion Problem.
1981-11-01
Korteweg - deVries Equation ," J. Math. Phys., 18, 2445 (1977). Kay, I., "The Inverse Scattering Problem," Report No. EM-74 of the Institute of Mathematical...3.2 Comparison of the IWKB Method with the Full-Wave Method for Profiles for Which the Full-Wave Equation can be Solved for Exactly 45 3.2.1 General...Section 2 describes the automatic scaling of Digisonde ionograms, and Section 3 investigates the possibility of solving the Schroedinger wave equation for
Slow-wave analysis on double layered substrates
NASA Astrophysics Data System (ADS)
Hindy, M. A.
Full wave analysis of a slow-wave microstrip transmission line on ferromagnetic semiconductor with insulator is presented. Spectral domain method with sampling theorem are used. A new current distribution is applied. The obtained slow-wave factor is higher than that when using lossless ferromagnetic material only. Phase shifting is achieved also by the same structure.
Modeling RF Fields in Hot Plasmas with Parallel Full Wave Code
NASA Astrophysics Data System (ADS)
Spencer, Andrew; Svidzinski, Vladimir; Zhao, Liangji; Galkin, Sergei; Kim, Jin-Soo
2016-10-01
FAR-TECH, Inc. is developing a suite of full wave RF plasma codes. It is based on a meshless formulation in configuration space with adapted cloud of computational points (CCP) capability and using the hot plasma conductivity kernel to model the nonlocal plasma dielectric response. The conductivity kernel is calculated by numerically integrating the linearized Vlasov equation along unperturbed particle trajectories. Work has been done on the following calculations: 1) the conductivity kernel in hot plasmas, 2) a monitor function based on analytic solutions of the cold-plasma dispersion relation, 3) an adaptive CCP based on the monitor function, 4) stencils to approximate the wave equations on the CCP, 5) the solution to the full wave equations in the cold-plasma model in tokamak geometry for ECRH and ICRH range of frequencies, and 6) the solution to the wave equations using the calculated hot plasma conductivity kernel. We will present results on using a meshless formulation on adaptive CCP to solve the wave equations and on implementing the non-local hot plasma dielectric response to the wave equations. The presentation will include numerical results of wave propagation and absorption in the cold and hot tokamak plasma RF models, using DIII-D geometry and plasma parameters. Work is supported by the U.S. DOE SBIR program.
NASA Technical Reports Server (NTRS)
Shertzer, Janine; Temkin, Aaron
2004-01-01
The development of a practical method of accurately calculating the full scattering amplitude, without making a partial wave 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 wave function. The scattering amplitude can most accurately be calculated from an integral expression for the amplitude; that integral can be formally simplified, and then evaluated using the numerically determined wave function. The results are essentially identical to converged partial wave results.
Applications of elastic full waveform inversion to shallow seismic surface waves
NASA Astrophysics Data System (ADS)
Bohlen, Thomas; Forbriger, Thomas; Groos, Lisa; Schäfer, Martin; Metz, Tilman
2015-04-01
Shallow-seismic Rayleigh waves are attractive for geotechnical site investigations. They exhibit a high signal to noise ratio in field data recordings and have a high sensitivity to the S-wave velocity, an important lithological and geotechnical parameter to characterize the very shallow subsurface. Established inversion methods assume (local) 1-D subsurface models, and allow the reconstruction of the S-wave velocity as a function of depth by inverting the dispersion properties of the Rayleigh waves. These classical methods, however, fail if significant lateral variations of medium properties are present. Then the full waveform inversion (FWI) of the elastic wave field seems to be the only solution. Moreover, FWI may have the potential to recover multi-parameter models of seismic wave velocities, attenuation and eventually mass density. Our 2-D elastic FWI is a conjugate-gradient method where the gradient of the misfit function is calculated by the time-domain adjoint method. The viscoelastic forward modelling is performed with a classical staggered-grid 2-D finite-difference forward solver. Viscoelastic damping is implemented in the time-domain by a generalized standard linear solid. We use a multi-scale inversion approach by applying frequency filtering in the inversion. We start with the lowest frequency oft the field data and increase the upper corner frequency sequentially. Our modelling and FWI software is freely available under the terms of GNU GPL on www.opentoast.de. In recent years we studied the applicability of two-dimensional elastic FWI using numerous synthetic reconstruction tests and several field data examples. Important pre-processing steps for the application of 2-D elastic FWI to shallow-seismic field data are the 3D to 2D correction of geometrical spreading and the estimation of a priori Q-values that must be used as a passive medium parameter during the FWI. Furthermore, a source-wavelet correction filter should be applied during the FWI
Analysis of flexural wave cloaks
NASA Astrophysics Data System (ADS)
Climente, Alfonso; Torrent, Daniel; Sánchez-Dehesa, José
2016-12-01
This work presents a comprehensive study of the cloak for bending waves theoretically proposed by Farhat et al. [see Phys. Rev. Lett. 103, 024301 (2009)] and later on experimentally realized by Stenger et al. [see Phys. Rev. Lett. 108, 014301 (2012)]. This study uses a semi-analytical approach, the multilayer scattering method, which is based in the Kirchoff-Love wave equation for flexural waves in thin plates. Our approach was unable to reproduce the predicted behavior of the theoretically proposed cloak. This disagreement is here explained in terms of the simplified wave equation employed in the cloak design, which employed unusual boundary conditions for the cloaking shell. However, our approach reproduces fairly well the measured displacement maps for the fabricated cloak, indicating the validity of our approach. Also, the cloak quality has been here analyzed using the so called averaged visibility and the scattering cross section. The results obtained from both analysis let us to conclude that there is room for further improvements of this type of flexural wave cloak by using better design procedures.
BN-600 full MOX core benchmark analysis.
Kim, Y. I.; Hill, R. N.; Grimm, K.; Rimpault, G.; Newton, T.; Li, Z. H.; Rineiski, A.; Mohanakrishan, P.; Ishikawa, M.; Lee, K. B.; Danilytchev, A.; Stogov, V.; Nuclear Engineering Division; International Atomic Energy Agency; CEA SERCO Assurance; China Inst. of Atomic Energy; Forschnungszentrum Karlsruhe; Indira Gandhi Centre for Atomic Research; Japan Nuclear Cycle Development Inst.; Korea Atomic Energy Research Inst.; Inst. of Physics and Power Engineering
2004-01-01
As a follow-up of the BN-600 hybrid core benchmark, a full MOX core benchmark was performed within the framework of the IAEA co-ordinated research project. Discrepancies between the values of main reactivity coefficients obtained by the participants for the BN-600 full MOX core benchmark appear to be larger than those in the previous hybrid core benchmarks on traditional core configurations. This arises due to uncertainties in the proper modelling of the axial sodium plenum above the core. It was recognized that the sodium density coefficient strongly depends on the core model configuration of interest (hybrid core vs. fully MOX fuelled core with sodium plenum above the core) in conjunction with the calculation method (diffusion vs. transport theory). The effects of the discrepancies revealed between the participants results on the ULOF and UTOP transient behaviours of the BN-600 full MOX core were investigated in simplified transient analyses. Generally the diffusion approximation predicts more benign consequences for the ULOF accident but more hazardous ones for the UTOP accident when compared with the transport theory results. The heterogeneity effect does not have any significant effect on the simulation of the transient. The comparison of the transient analyses results concluded that the fuel Doppler coefficient and the sodium density coefficient are the two most important coefficients in understanding the ULOF transient behaviour. In particular, the uncertainty in evaluating the sodium density coefficient distribution has the largest impact on the description of reactor dynamics. This is because the maximum sodium temperature rise takes place at the top of the core and in the sodium plenum.
Fumeaux, Christophe; Lin, Hungyen; Serita, Kazunori; Withayachumnankul, Withawat; Kaufmann, Thomas; Tonouchi, Masayoshi; Abbott, Derek
2012-07-30
The process of terahertz generation through optical rectification in a nonlinear crystal is modeled using discretized equivalent current sources. The equivalent terahertz sources are distributed in the active volume and computed based on a separately modeled near-infrared pump beam. This approach can be used to define an appropriate excitation for full-wave electromagnetic numerical simulations of the generated terahertz radiation. This enables predictive modeling of the near-field interactions of the terahertz beam with micro-structured samples, e.g. in a near-field time-resolved microscopy system. The distributed source model is described in detail, and an implementation in a particular full-wave simulation tool is presented. The numerical results are then validated through a series of measurements on square apertures. The general principle can be applied to other nonlinear processes with possible implementation in any full-wave numerical electromagnetic solver.
Simulations of NBI-ICRF synergy with the full-wave TORIC package
Bilato, R.; Brambilla, M.; Horton, L. D.; Maggi, C. F.; Stober, J.
2009-11-26
During the combined plasma heating with neutral beam injection (NBI) and waves in the ion cyclotron (IC) range of frequencies, the NBI fast ions are preferentially accelerated by IC waves close to the IC harmonics, as a consequence of finite Larmor radius (FLR) effects. Since the NBI fast ions are expected to have a strong influence on the wave absorption and propagation, we have implemented a NBI source in the quasilinear Fokker-Planck SSFPQL code, interfaced with the toroidal full-wave TORIC solver. In this implementation the NBI ionization sources are obtained from the output of a Monte Carlo code, such as FAFNER. The numerical scheme adopted in the TORIC-SSFPQL package allows to describe very anisotropic sources, such as NBI, and to iterate the solution of Maxwell's equation taking into account selfconsistently the fast ion tails. As a first application, we present modeling of an ASDEX-Upgrade discharge with combined NBI and ICRF heating.
Full wave simulations of fast wave heating losses in the scrape-off layer of NSTX and NSTX-U
Bertelli, Nicola; Jaeger, E. F.; Hosea, J.; Phillips, C. K.; Berry, Lee Alan; Gerhardt, S.; Green, David L; LeBlanc, B; Perkins, R. J.; Ryan, Philip Michael; Taylor, G.; Valeo, E. J.; Wilson, J. R.
2014-01-01
Full wave simulations of fusion plasmas show a direct correlation between the location of the fast-wave cut-off, radiofrequency (RF) field amplitude in the scrape-off layer (SOL) and the RF power losses in the SOL observed in the National Spherical Torus eXperiment (NSTX). In particular, the RF power losses in the SOL increase significantly when the launched waves transition from evanescent to propagating in that region. Subsequently, a large amplitude electric field occurs in the SOL, driving RF power losses when a proxy collisional loss term is added. A 3D reconstruction of absorbed power in the SOL is presented showing agreement with the RF experiments in NSTX. Loss predictions for the future experiment NSTX-Upgrade (NSTX-U) are also obtained and discussed.
Offshore Structure of the Cascadia Subduction Zone from Full-wave Tomography
NASA Astrophysics Data System (ADS)
Gao, H.
2014-12-01
We construct a preliminary offshore model of the crust and uppermost mantle at the Cascadia subduction zone using a full-wave tomographic method. We include the ocean bottom seismometers deployed by the Cascadia Initiative community experiment and Neptune Canada from 2011-2013, and the available broadband stations on land. We have extracted the empirical Green's functions from continuous seismic records on the vertical components of the OBS and inland station pairs with a frequency-time normalization method, which provide useful Rayleigh-wave signals within the periods of 7-50 s. We have also selected ~50 regional earthquakes between 2011-2013 offshore of the Cascadia subduction zone, which generated useful surface-wave signals up to 75 s period. We simulate wave propagation within a 3D Earth structure using a finite-difference method to generate a station Strain Greens Tensor database and synthetic waveforms. Rayleigh wave phase delays are obtained by cross-correlating the observed and synthetic waveforms. The sensitivity kernels of Rayleigh waves on the perturbations of Vp and Vs are calculated based on the Strain Greens Tensor database. We then invert for the velocity perturbation from the reference model and progressively improve the model resolution. Our preliminary full-wave tomographic imaging using the EGFs and earthquake Rayleigh waves shows: (1) Segmented low-velocity anomalies along the forearc, which are spatially correlated with the patterns of offshore basins and high slip patches; (2) Low velocities beneath the Blanco fracture zone; (3) The distribution of pseudofaults defines the seismic velocity heterogeneities; and (4) A low-velocity zone beneath the oceanic Moho near the trench, which may indicate serpentinization of the mantle lithosphere.
Full wave dc-to-dc converter using energy storage transformers
NASA Technical Reports Server (NTRS)
Moore, E. T.; Wilson, T. G.
1969-01-01
Full wave dc-to-dc converter, for an ion thrustor, uses energy storage transformers to provide a method of dc-to-dc conversion and regulation. The converter has a high degree of physical simplicity, is lightweight and has high efficiency.
Basic full-wave generalization of the real-argument Hermite-Gauss beam.
Seshadri, S R
2010-05-01
The linearly polarized real-argument Hermite-Gauss beam is investigated by the Fourier transform method. The complex power is obtained and the reactive power of the paraxial beam is found to be zero. The complex space source required for the full-wave generalization of the real-argument Hermite-Gauss beam is deduced. The resulting basic full real-argument Hermite-Gauss wave is determined. The real and the reactive powers of the full wave are evaluated. The reactive power of the basic full real-argument Hermite-Gauss wave is infinite, and the reasons for this singularity are described. The real power depends on kw(0), m, and n, where k is the wavenumber, w(0) is the e-folding distance of the Gaussian part of the input distribution, and m and n are the mode numbers. The variation in the real power with respect to changes in kw(0) for specified m and n as well as with respect to changes in m and n for a specified kw(0) is examined.
Enhanced Doppler reflectometry power response: physical optics and 2D full wave modelling
NASA Astrophysics Data System (ADS)
Pinzón, J. R.; Happel, T.; Blanco, E.; Conway, G. D.; Estrada, T.; Stroth, U.
2017-03-01
The power response of a Doppler reflectometer is investigated by means of the physical optics model; a simple model which considers basic scattering processes at the reflection layer. Apart from linear and saturated scattering regimes, non-linear regimes with an enhanced backscattered power are found. The different regimes are characterized and understood based on analytical calculations. The power response is also studied with two-dimensional full wave simulations, where the enhanced backscattered power regimes are also found in qualitative agreement with the physical optics results. The ordinary and extraordinary modes are compared for the same angle of incidence, with the conclusion that the ordinary mode is better suited for Doppler reflectometry turbulence level measurements due to the linearity of its response. The scattering efficiency is studied and a first approximation to describe it is proposed. At the end, the application of the physical optics results to experimental data analysis is discussed. In particular, a formula to assess the linearity of Doppler reflectometry measurements is provided.
An assessment of full wave effects on the propagation and absorption of lower hybrid wavesa)
NASA Astrophysics Data System (ADS)
Wright, J. C.; Bonoli, P. T.; Schmidt, A. E.; Phillips, C. K.; Valeo, E. J.; Harvey, R. W.; Brambilla, M. A.
2009-07-01
Lower hybrid (LH) waves (Ωci≪ω≪Ωce, where Ωi ,e≡Zi ,eeB/mi ,ec) have the attractive property of damping strongly via electron Landau resonance on relatively fast tail electrons and consequently are well-suited to driving current. Established modeling techniques use Wentzel-Kramers-Brillouin (WKB) expansions with self-consistent non-Maxwellian distributions. Higher order WKB expansions have shown some effects on the parallel wave number evolution and consequently on the damping due to diffraction [G. Pereverzev, Nucl. Fusion 32, 1091 (1991)]. A massively parallel version of the TORIC full wave electromagnetic field solver valid in the LH range of frequencies has been developed [J. C. Wright et al., Comm. Comp. Phys. 4, 545 (2008)] and coupled to an electron Fokker-Planck solver CQL3D [R. W. Harvey and M. G. McCoy, in Proceedings of the IAEA Technical Committee Meeting, Montreal, 1992 (IAEA Institute of Physics Publishing, Vienna, 1993), USDOC/NTIS Document No. DE93002962, pp. 489-526] in order to self-consistently evolve nonthermal electron distributions characteristic of LH current drive (LHCD) experiments in devices such as Alcator C-Mod and ITER (B0≈5 T, ne0≈1×1020 m-3). These simulations represent the first ever self-consistent simulations of LHCD utilizing both a full wave and Fokker-Planck calculation in toroidal geometry.
Changes in P-wave velocity with different full waveform sonic transmitter centre frequency
NASA Astrophysics Data System (ADS)
Almalki, Majed; Harris, Brett; Dupuis, J. Christian
2015-05-01
Full waveform sonic logging, with the transmitter set at different centre frequencies, often provides different compressional wave velocities over the same interval. There may be several reasons why these velocity differences are recovered where the source has different frequency content. Examples include: intrinsic dispersion, scattering dispersion, geometric dispersion, processing artefacts and acquisition artefacts. We acquired and analysed multifrequency monopole full waveform sonic logging data from the cored drill hole intersecting a high-permeability sandy aquifer in the Northern Gnangara Mound, Perth Basin, Western Australia. A key interval of the shallow, sand-dominated Yarragadee Formation was selected and logged four times with transmitter centre frequencies set to 1, 3, 5 and 15 kHz. We compute apparent velocity dispersion as the percentage velocity differences in the P-wave velocity recovered from full waveform sonic logs completed at different dominant transmitter centre frequencies. We find that high-permeability sediments could be placed into broad groups: cross-bedded and non-cross-bedded sandstones. We find a distinctly different relationship between apparent P-wave velocity dispersion and permeability for cross-bedded and non-cross-bedded sandstones. Cross plots for the two sediment types show a general trend of increasing apparent dispersion with increasing permeability. Grouping the sandstone layers based on sediment type, as observed from core samples, illustrates different but positive correlation between the apparent P-wave velocity dispersion and permeability in these shallow, weakly-consolidated sandstones. The cross-bedded sandstone, for its part, has a wider range of permeability than the non-cross-bedded sandstone but a smaller range of apparent P-wave velocity dispersion. Given these results, our hypothesis is that while permeability plays a role, other factors such as geometric dispersion or scattering dispersion likely contribute the
Imaging of transient surface acoustic waves by full-field photorefractive interferometry
Xiong, Jichuan; Xu, Xiaodong E-mail: christ.glorieux@fys.kuleuven.be; Glorieux, Christ E-mail: christ.glorieux@fys.kuleuven.be; Matsuda, Osamu; Cheng, Liping
2015-05-15
A stroboscopic full-field imaging technique based on photorefractive interferometry for the visualization of rapidly changing surface displacement fields by using of a standard charge-coupled device (CCD) camera is presented. The photorefractive buildup of the space charge field during and after probe laser pulses is simulated numerically. The resulting anisotropic diffraction upon the refractive index grating and the interference between the polarization-rotated diffracted reference beam and the transmitted signal beam are modeled theoretically. The method is experimentally demonstrated by full-field imaging of the propagation of photoacoustically generated surface acoustic waves with a temporal resolution of nanoseconds. The surface acoustic wave propagation in a 23 mm × 17 mm area on an aluminum plate was visualized with 520 × 696 pixels of the CCD sensor, yielding a spatial resolution of 33 μm. The short pulse duration (8 ns) of the probe laser yields the capability of imaging SAWs with frequencies up to 60 MHz.
Modeling of EAST ICRF antenna performance using the full-wave code TORIC
Edlund, E. M.; Bonoli, P. T.; Porkolab, M.; Wukitch, S. J.
2015-12-10
Access to advanced operating regimes in the EAST tokamak will require a combination of electron-cyclotron resonance heating (ECRH), neutral beam injection (NBI) and ion cyclotron range frequency heating (ICRF), with the addition of lower-hybrid current drive (LHCD) for current profile control. Prior experiments at the EAST tokamak facility have shown relatively weak response of the plasma temperature to application of ICRF heating, with typical coupled power about 2 MW out of 12 MW source. The launched spectrum, at n{sub φ} = 34 for 0-π -0-π phasing and 27 MHz, is largely inaccessible at line-averaged densities of approximately 2 × 10{sup 19} m{sup −3}. However, with variable antenna phasing and frequency, this system has considerable latitude to explore different heating schemes. To develop an ICRF actuator control model, we have used the full-wave code TORIC to explore the physics of ICRF wave propagation in EAST. The results presented from this study use a spectrum analysis using a superposition of n{sub φ} spanning −50 to +50. The low density regime typical of EAST plasmas results in a perpendicular wavelength comparable to the minor radius which results in global cavity resonance effects and eigenmode formation when the single-pass absorption is low. This behavior indicates that improved performance can be attained by lowering the peak of the k{sub ||} spectrum by using π/3 phasing of the 4-strap antenna. Based on prior studies conducted at Alcator C-Mod, this phasing is also expected to have the advantage of nearly divergence-free box currents, which should result in reduced levels of impurity production. Significant enhancements of the loading resistance may be achieved by using low k{sub ||} phasing and a combination of magnetic field and frequency to vary the location of the resonance and mode conversion regions. TORIC calculations indicate that the significant power may be channeled to the electrons and deuterium majority. We expect that
Modeling of EAST ICRF antenna performance using the full-wave code TORIC
NASA Astrophysics Data System (ADS)
Edlund, E. M.; Bonoli, P. T.; Porkolab, M.; Wukitch, S. J.
2015-12-01
Access to advanced operating regimes in the EAST tokamak will require a combination of electron-cyclotron resonance heating (ECRH), neutral beam injection (NBI) and ion cyclotron range frequency heating (ICRF), with the addition of lower-hybrid current drive (LHCD) for current profile control. Prior experiments at the EAST tokamak facility have shown relatively weak response of the plasma temperature to application of ICRF heating, with typical coupled power about 2 MW out of 12 MW source. The launched spectrum, at nφ = 34 for 0-π -0-π phasing and 27 MHz, is largely inaccessible at line-averaged densities of approximately 2 × 1019 m-3. However, with variable antenna phasing and frequency, this system has considerable latitude to explore different heating schemes. To develop an ICRF actuator control model, we have used the full-wave code TORIC to explore the physics of ICRF wave propagation in EAST. The results presented from this study use a spectrum analysis using a superposition of nφ spanning -50 to +50. The low density regime typical of EAST plasmas results in a perpendicular wavelength comparable to the minor radius which results in global cavity resonance effects and eigenmode formation when the single-pass absorption is low. This behavior indicates that improved performance can be attained by lowering the peak of the k|| spectrum by using π/3 phasing of the 4-strap antenna. Based on prior studies conducted at Alcator C-Mod, this phasing is also expected to have the advantage of nearly divergence-free box currents, which should result in reduced levels of impurity production. Significant enhancements of the loading resistance may be achieved by using low k|| phasing and a combination of magnetic field and frequency to vary the location of the resonance and mode conversion regions. TORIC calculations indicate that the significant power may be channeled to the electrons and deuterium majority. We expect that implementation of these recommendations in EAST
Multi-Grid and Resolution Full-Wave Tomography and Moment Tensor Inversion (Postprint)
2012-06-04
have been carried out to obtain a joint P and S velocity model. Preliminary results clearly show high-velocity anomalies associated with plate ...clearly show high-velocity anomalies associated with plate subduction beneath Indonesia, southern Tibet, Iran, and the Hellenic arc. The African...depth from full-wave ambient noise tomography. The color scale is velocity perturbation (%) relative to the average model. The plate boundaries are
Three dimensional full-wave nonlinear acoustic simulations: Applications to ultrasound imaging
NASA Astrophysics Data System (ADS)
Pinton, Gianmarco
2015-10-01
Characterization of acoustic waves that propagate nonlinearly in an inhomogeneous medium has significant applications to diagnostic and therapeutic ultrasound. The generation of an ultrasound image of human tissue is based on the complex physics of acoustic wave propagation: diffraction, reflection, scattering, frequency dependent attenuation, and nonlinearity. The nonlinearity of wave propagation is used to the advantage of diagnostic scanners that use the harmonic components of the ultrasonic signal to improve the resolution and penetration of clinical scanners. One approach to simulating ultrasound images is to make approximations that can reduce the physics to systems that have a low computational cost. Here a maximalist approach is taken and the full three dimensional wave physics is simulated with finite differences. This paper demonstrates how finite difference simulations for the nonlinear acoustic wave equation can be used to generate physically realistic two and three dimensional ultrasound images anywhere in the body. A specific intercostal liver imaging scenario for two cases: with the ribs in place, and with the ribs removed. This configuration provides an imaging scenario that cannot be performed in vivo but that can test the influence of the ribs on image quality. Several imaging properties are studied, in particular the beamplots, the spatial coherence at the transducer surface, the distributed phase aberration, and the lesion detectability for imaging at the fundamental and harmonic frequencies. The results indicate, counterintuitively, that at the fundamental frequency the beamplot improves due to the apodization effect of the ribs but at the same time there is more degradation from reverberation clutter. At the harmonic frequency there is significantly less improvement in the beamplot and also significantly less degradation from reverberation. It is shown that even though simulating the full propagation physics is computationally challenging it
Three dimensional full-wave nonlinear acoustic simulations: Applications to ultrasound imaging
Pinton, Gianmarco
2015-10-28
Characterization of acoustic waves that propagate nonlinearly in an inhomogeneous medium has significant applications to diagnostic and therapeutic ultrasound. The generation of an ultrasound image of human tissue is based on the complex physics of acoustic wave propagation: diffraction, reflection, scattering, frequency dependent attenuation, and nonlinearity. The nonlinearity of wave propagation is used to the advantage of diagnostic scanners that use the harmonic components of the ultrasonic signal to improve the resolution and penetration of clinical scanners. One approach to simulating ultrasound images is to make approximations that can reduce the physics to systems that have a low computational cost. Here a maximalist approach is taken and the full three dimensional wave physics is simulated with finite differences. This paper demonstrates how finite difference simulations for the nonlinear acoustic wave equation can be used to generate physically realistic two and three dimensional ultrasound images anywhere in the body. A specific intercostal liver imaging scenario for two cases: with the ribs in place, and with the ribs removed. This configuration provides an imaging scenario that cannot be performed in vivo but that can test the influence of the ribs on image quality. Several imaging properties are studied, in particular the beamplots, the spatial coherence at the transducer surface, the distributed phase aberration, and the lesion detectability for imaging at the fundamental and harmonic frequencies. The results indicate, counterintuitively, that at the fundamental frequency the beamplot improves due to the apodization effect of the ribs but at the same time there is more degradation from reverberation clutter. At the harmonic frequency there is significantly less improvement in the beamplot and also significantly less degradation from reverberation. It is shown that even though simulating the full propagation physics is computationally challenging it
Nonlinear Fourier analysis with cnoidal waves
Osborne, A.R.
1996-12-31
Fourier analysis is one of the most useful tools to the ocean engineer. The approach allows one to analyze wave data and thereby to describe a dynamical motion in terms of a linear superposition of ordinary sine waves. Furthermore, the Fourier technique allows one to compute the response function of a fixed or floating structure: each sine wave in the wave or force spectrum yields a sine wave in the response spectrum. The counting of fatigue cycles is another area where the predictable oscillations of sine waves yield procedures for the estimation of the fatigue life of structures. The ocean environment, however, is a source of a number of nonlinear effects which must also be included in structure design. Nonlinearities in ocean waves deform the sinusoidal shapes into other kinds of waves such as the Stokes wave, cnoidal wave or solitary wave. A key question is: Does there exist a generalization of linear Fourier analysis which uses nonlinear basis functions rather than the familiar sine waves? Herein addresses the dynamics of nonlinear wave motion in shallow water where the basis functions are cnoidal waves and discuss nonlinear Fourier analysis in terms of a linear superposition of cnoidal waves plus their mutual nonlinear interactions. He gives a number of simple examples of nonlinear Fourier wave motion and then analyzes an actual surface-wave time series obtained on an offshore platform in the Adriatic Sea. Finally, he briefly discusses application of the cnoidal wave spectral approach to the computation of the frequency response function of a floating vessel. The results given herein will prove useful in future engineering studies for the design of fixed, floating and complaint offshore structures.
Ion cyclotron emission calculations using a 2D full wave numerical code
NASA Astrophysics Data System (ADS)
Batchelor, D. B.; Jaeger, E. F.; Colestock, P. L.
1987-09-01
Measurement of radiation in the HF band due to cyclotron emission by energetic ions produced by fusion reactions or neutral beam injection promises to be a useful diagnostic on large devices which are entering the reactor regime of operation. A number of complications make the modelling and interpretation of such measurements difficult using conventional geometrical optics methods. In particular the long wavelength and lack of high directivity of antennas in this frequency regime make observation of a single path across the plasma into a viewing dump impractical. Pickup antennas effectively see the whole plasma and wall reflection effects are important. We have modified our 2D full wave ICRH code2 to calculate wave fields due to a distribution of energetic ions in tokamak geometry. The radiation is modeled as due to an ensemble of localized source currents distributed in space. The spatial structure of the coherent wave field is then calculated including cyclotron harmonic damping as compared to the usual procedure of incoherently summing powers of individual radiators. This method has the advantage that phase information from localized radiating currents is globally retained so the directivity of the pickup antennas is correctly represented. Also standing waves and wall reflections are automatically included.
Full elastic characterization of absorptive rubber using laser excited guided ultrasonic waves
NASA Astrophysics Data System (ADS)
Verstraeten, Bert; Xu, Xiadong; Martinez, Loïc; Glorieux, Christ
2012-05-01
Because of the highly damping nature of rubber, it is difficult to characterize its dynamic elastic properties using classical methods. In this paper, an experimental approach employing laser excited guided acoustic waves is proposed to accurately determine the real and imaginary part of the longitudinal and shear elastic modulus of a rubber layer. From the spatiotemporal evolution of a propagating laser excited Lamb wave measured by a laser Doppler vibrometer, which is scanning along a line perpendicular to a line of excitation, the phase velocity dispersion curves in the wave number - frequency domain are obtained. The results are interpreted in the framework of a detailed semianalytical study, analyzing the influence of elastic damping on the Lamb dispersion curves. This analysis is exploited to adequately fit the experimental dispersion curves and thus extract information about the elastic moduli and absorption coefficients of the rubber plate. The results are validated by a pulse-echo measurement, and by guided wave propagation results with the rubber layer connected in a bi-layer plate configuration to non-damping plates.
Acoustic modal analysis of a full-scale annular combustor
NASA Technical Reports Server (NTRS)
Karchmer, A. M.
1982-01-01
An acoustic modal decomposition of the measured pressure field in a full scale annular combustor installed in a ducted test rig is described. The modal analysis, utilizing a least squares optimization routine, is facilitated by the assumption of randomly occurring pressure disturbances which generate equal amplitude clockwise and counter-clockwise pressure waves, and the assumption of statistical independence between modes. These assumptions are fully justified by the measured cross spectral phases between the various measurement points. The resultant modal decomposition indicates that higher order modes compose the dominant portion of the combustor pressure spectrum in the range of frequencies of interest in core noise studies. A second major finding is that, over the frequency range of interest, each individual mode which is present exists in virtual isolation over significant portions of the spectrum. Finally, a comparison between the present results and a limited amount of data obtained in an operating turbofan engine with the same combustor is made. The comparison is sufficiently favorable to warrant the conclusion that the structure of the combustor pressure field is preserved between the component facility and the engine.
Full-wave modeling of the O-X mode conversion in the Pegasus toroidal experiment
Koehn, A.; Jacquot, J.; Bongard, M. W.; Hinson, E. T.; Volpe, F. A.; Gallian, S.
2011-08-15
The ordinary-extraordinary (O-X) mode conversion is modeled with the aid of a 2D full-wave code in the Pegasus toroidal experiment as a function of the launch angles. It is shown how the shape of the plasma density profile in front of the antenna can significantly influence the mode conversion efficiency and, thus, the generation of electron Bernstein waves (EBWs). It is therefore desirable to control the density profile in front of the antenna for successful operation of an EBW heating and current drive system. On the other hand, the conversion efficiency is shown to be resilient to vertical displacements of the plasma as large as {+-}10 cm.
Calculation of the Full Scattering Amplitude without Partial Wave Decomposition II
NASA Technical Reports Server (NTRS)
Shertzer, J.; Temkin, A.
2003-01-01
As is well known, the full scattering amplitude can be expressed as an integral involving the complete scattering wave function. We have shown that the integral can be simplified and used in a practical way. Initial application to electron-hydrogen scattering without exchange was highly successful. The Schrodinger equation (SE) can be reduced to a 2d partial differential equation (pde), and was solved using the finite element method. We have now included exchange by solving the resultant SE, in the static exchange approximation. The resultant equation can be reduced to a pair of coupled pde's, to which the finite element method can still be applied. The resultant scattering amplitudes, both singlet and triplet, as a function of angle can be calculated for various energies. The results are in excellent agreement with converged partial wave results.
NASA Technical Reports Server (NTRS)
Shertzer, Janine; Temkin, A.
2003-01-01
As is well known, the full scattering amplitude can be expressed as an integral involving the complete scattering wave function. We have shown that the integral can be simplified and used in a practical way. Initial application to electron-hydrogen scattering without exchange was highly successful. The Schrodinger equation (SE), which can be reduced to a 2d partial differential equation (pde), was solved using the finite element method. We have now included exchange by solving the resultant SE, in the static exchange approximation, which is reducible to a pair of coupled pde's. The resultant scattering amplitudes, both singlet and triplet, calculated as a function of energy are in excellent agreement with converged partial wave results.
A simple derivation of relativistic full-wave equations at electron cyclotron resonance
NASA Astrophysics Data System (ADS)
McDonald, D. C.; Cairns, R. A.; Lashmore-Davies, C. N.
1994-10-01
When a wave passes through an electron gyroresonance, in a plasma in the presence of a magnetic field gradient, there is a small spread in the resonance due to the electron's Larmor radius. Mathematically this is represented by the inclusion of the so called gyrokinetic term in the resonance condition, Lashmore-Davies and Dendy. The smallness of this term, compared with other effects such as relativistic broadening, suggests that it should be negligible. However, we shall show here, by extending the method of Cairns et al., into the relativistic regime, that its inclusion is vital for producing self consistent full-wave equations which describe electron gyroresonance. The method is considerably simpler than those used previously by Maroli et al., Petrillo et al., and Lampis et al., for obtaining similar equations. As an example we include a calculation for the O-Mode passing perpendicularly through the fundamental.
Analysis of Waves in the Near-Field of Wave Energy Converter Arrays through Stereo Video
NASA Astrophysics Data System (ADS)
Black, C.; Haller, M. C.
2013-12-01
Oregon State University conducted a series of laboratory experiments to measure and quantify the near-field wave effects caused within arrays of 3 and 5 Wave Energy Converters (WEC). As the waves and WECs interact, significant scattering and radiation occurs increasing/decreasing the wave heights as well as changing the direction the wave is traveling. These effects may vary based on the number of WECs within an array and their respective locations. The findings of this analysis will assist in selecting the WEC farm location and in improving WEC design. Analyzing the near-field waves will help determine the relative importance of absorption, scattering, and radiation as a function of the incident wave conditions and device performance. The WEC mooring system design specifications may also be impacted if the wave heights in the near-field are greater than expected. It is imperative to fully understand the near-field waves before full-scale WEC farms can be installed. Columbia Power Technologies' Manta served as the test WEC prototype on a 1 to 33 scale. Twenty-three wave gages measured the wave heights in both regular and real sea conditions at locations surrounding and within the WEC arrays. While these gages give a good overall picture of the water elevation behavior, it is difficult to resolve the complicated wave field within the WEC array using point gages. Here stereo video techniques are applied to extract the 3D water surface elevations at high resolution in order to reconstruct the multi-directional wave field in the near-field of the WEC array. The video derived wave information will also be compared against the wave gage data.
Gravitational-wave detection using multivariate analysis
NASA Astrophysics Data System (ADS)
Adams, Thomas S.; Meacher, Duncan; Clark, James; Sutton, Patrick J.; Jones, Gareth; Minot, Ariana
2013-09-01
Searches for gravitational-wave bursts (transient signals, typically of unknown waveform) require identification of weak signals in background detector noise. The sensitivity of such searches is often critically limited by non-Gaussian noise fluctuations that are difficult to distinguish from real signals, posing a key problem for transient gravitational-wave astronomy. Current noise rejection tests are based on the analysis of a relatively small number of measured properties of the candidate signal, typically correlations between detectors. Multivariate analysis (MVA) techniques probe the full space of measured properties of events in an attempt to maximize the power to accurately classify events as signal or background. This is done by taking samples of known background events and (simulated) signal events to train the MVA classifier, which can then be applied to classify events of unknown type. We apply the boosted decision tree (BDT) MVA technique to the problem of detecting gravitational-wave bursts associated with gamma-ray bursts. We find that BDTs are able to increase the sensitive distance reach of the search by as much as 50%, corresponding to a factor of ˜3 increase in sensitive volume. This improvement is robust against trigger sky position, large sky localization error, poor data quality, and the simulated signal waveforms that are used. Critically, we find that the BDT analysis is able to detect signals that have different morphologies from those used in the classifier training and that this improvement extends to false alarm probabilities beyond the 3σ significance level. These findings indicate that MVA techniques may be used for the robust detection of gravitational-wave bursts with a priori unknown waveform.
Development of full wave code for modeling RF fields in hot non-uniform plasmas
NASA Astrophysics Data System (ADS)
Zhao, Liangji; Svidzinski, Vladimir; Spencer, Andrew; Kim, Jin-Soo
2016-10-01
FAR-TECH, Inc. is developing a full wave RF modeling code to model RF fields in fusion devices and in general plasma applications. As an important component of the code, an adaptive meshless technique is introduced to solve the wave equations, which allows resolving plasma resonances efficiently and adapting to the complexity of antenna geometry and device boundary. The computational points are generated using either a point elimination method or a force balancing method based on the monitor function, which is calculated by solving the cold plasma dispersion equation locally. Another part of the code is the conductivity kernel calculation, used for modeling the nonlocal hot plasma dielectric response. The conductivity kernel is calculated on a coarse grid of test points and then interpolated linearly onto the computational points. All the components of the code are parallelized using MPI and OpenMP libraries to optimize the execution speed and memory. The algorithm and the results of our numerical approach to solving 2-D wave equations in a tokamak geometry will be presented. Work is supported by the U.S. DOE SBIR program.
NASA Astrophysics Data System (ADS)
Li, Chunhui; Guan, Guangying; Huang, Zhihong; Wang, Ruikang K.; Nabi, Ghulam
2015-03-01
By combining with the phase sensitive optical coherence tomography (PhS-OCT), vibration and surface acoustic wave (SAW) methods have been reported to provide elastography of skin tissue respectively. However, neither of these two methods can provide the elastography in full skin depth in current systems. This paper presents a feasibility study on an optical coherence elastography method which combines both vibration and SAW in order to give the quantitative mechanical properties of skin tissue with full depth range, including epidermis, dermis and subcutaneous fat. Experiments are carried out on layered tissue mimicking phantoms and in vivo human forearm and palm skin. A ring actuator generates vibration while a line actuator were used to excited SAWs. A PhS-OCT system is employed to provide the ultrahigh sensitive measurement of the generated waves. The experimental results demonstrate that by the combination of vibration and SAW method the full skin bulk mechanical properties can be quantitatively measured and further the elastography can be obtained with a sensing depth from ~0mm to ~4mm. This method is promising to apply in clinics where the quantitative elasticity of localized skin diseases is needed to aid the diagnosis and treatment.
Full Waveform 2.5D Teleseismic Surface Wave Tomography with Application to the Tien Shan
NASA Astrophysics Data System (ADS)
Roecker, S. W.; Priestley, K. F.; Baker, B. I.
2011-12-01
We adapt the 2.5D spectral domain finite difference waveform tomography algorithm of Roecker et al. (2010) to permit the analysis of teleseismically recorded surface waves. The teleseismic body wave technique of generating synthetic waveforms by specifying an analytic solution for a background wavefield in a 1D model and solving for a scattered field excited by this background is equally applicable to surface waves. We use the locked mode approach of Gomberg and Masters (1988) to calculate the background Greens functions at each point of the finite difference (FD) grid. Because of the much greater concentration of energy at the surface, we adopt the cell-based FD operators of Min et al. (2004) to calculate the free surface boundary conditions, and the generalized stretching function of Komatitch and Martin (2007) to improve the absorption in the PML. We use this algorithm to analyze broad band seismograms of events in Sumatra recorded by the MANAS array in the Tien Shan. Our results show that the upper mantle beneath much of the central Tien Shan has shear wavespeeds at least 10% lower than the lithosphere beneath the Tarim basin to the south or the Kazach shield to the north. At the same time, there appears to be a remnant lithospheric lid beneath the Kyrgyz range in the north, an observation consistent with previous receiver function studies in this area.
Trend analysis of the wave storminess: the wave direction
NASA Astrophysics Data System (ADS)
Casas Prat, M.; Sierra, J. P.; Mösso, C.; Sánchez-Arcilla, A.
2009-09-01
directionality. It is based on 44 year hindcast model data (1958-2001) of the HIPOCAS project, enabling to work with a longer time series compared to the existing measured ones. 41 nodes of this database are used, containing 3 hourly simulated data of significant wave height and wave direction, among other parameters. For storm definition, the Peak Over Threshold (POT) method is used with some additional duration requirements in order to analyse statistically independent events (Mendoza & Jiménez, 2006). Including both wave height and storm duration, the wave storminess is characterised by the energy content (Mendoza & Jiménez, 2004), being in turn log-transformed because of its positive scale. Separately, the wave directionality itself is analysed in terms of different sectors and approaching their probability of occurrence by counting events and using Bayesian inference (Agresti, 2002). Therefore, the original data is transformed into compositional data and, before performing the trend analysis, the isometric logratio (ilr) transformation (Egozcue et al., 2003) is done. In general, the trend analysis methodology consists in two steps: 1) trend detection and 2) trend quantification. For 1) the Mann Kendall test is used in order to identify the nodes with significant trend. For these selected nodes, the trend quantification is done, comparing two methods: 1) a simple linear regression analysis complemented with the bootstrap technique and 2) a Bayesian analysis, assuming normally distributed data with linearly increasing mean. Preliminary results show no significant trend for both annual mean and maximum energy content except for some nodes located to the Northern Catalan coast. Regarding the wave direction (but not only considering stormy conditions) there is a tendency of North direction to decrease whereas South and Southeast direction seems to increase.
In this paper we report the first multi-dimensional, full-wave, vector Maxwell’s equation solutions to problems describing the interaction of ultra...time domain (NL-FDTD) method which combines a nonlinear generalization of a standard, FDTD, full-wave, vector, linear Maxwell’s equation solver with
Further SEASAT SAR coastal ocean wave analysis
NASA Technical Reports Server (NTRS)
Kasischke, E. S.; Shuchman, R. A.; Meadows, G. A.; Jackson, P. L.; Tseng, Y.
1981-01-01
Analysis techniques used to exploit SEASAT synthetic aperture radar (SAR) data of gravity waves are discussed and the SEASAT SAR's ability to monitor large scale variations in gravity wave 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 wave data. It was determined that spectra generated from fast Fourier transform analysis (FFT) of SAR wave 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 waves 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.
Method for improving accuracy in full evaporation headspace analysis.
Xie, Wei-Qi; Chai, Xin-Sheng
2017-03-21
We report a new headspace analytical method in which multiple headspace extraction is incorporated with the full evaporation technique. The pressure uncertainty caused by the solid content change in the samples has a great impact to the measurement accuracy in the conventional full evaporation headspace analysis. The results (using ethanol solution as the model sample) showed that the present technique is effective to minimize such a problem. The proposed full evaporation multiple headspace extraction analysis technique is also automated and practical, and which could greatly broaden the applications of the full-evaporation-based headspace analysis. This article is protected by copyright. All rights reserved.
Rapid acquisition of high resolution full wave-field borehole seismic data
Sleefe, G.E.; Harding, R.S. Jr.; Fairborn, J.W.; Paulsson, B.N.P.
1993-04-01
An essential requirement for both Vertical Seismic Profiling (VSP) and Cross-Hole Seismic Profiling (CHSP) is the rapid acquisition of high resolution borehole seismic data. Additionally, full wave-field recording using three-component receivers enables the use of both transmitted and reflected elastic wave events in the resulting seismic images of the subsurface. To this end, an advanced three- component multi-station borehole seismic receiver system has been designed and developed by Sandia National Laboratory (SNL) and OYO Geospace. The system requires data from multiple three-component wall-locking accelerometer packages and telemeters digital data to the surface in real-time. Due to the multiplicity of measurement stations and the real-time data link, acquisition time for the borehole seismic survey is significantly reduced. The system was tested at the Chevron La Habra Test Site using Chevron`s clamped axial borehole vibrator as the seismic source. Several source and receiver fans were acquired using a four-station version of the advanced system. For comparison purposes, an equivalent data set was acquired using a standard analog wall-locking geophone receiver. The test data indicate several enhancements provided by the multi-station receiver relative to the standard, drastically improved signal-to-noise ratio, increased signal bandwidth, the detection of multiple reflectors, and a true 4:1 reduction in survey time.
Full-wave modeling of therapeutic ultrasound: Nonlinear ultrasound propagation in ideal fluids
NASA Astrophysics Data System (ADS)
Ginter, Siegfried; Liebler, Marko; Steiger, Eckard; Dreyer, Thomas; Riedlinger, Rainer E.
2002-05-01
The number of applications of high-intense, focused ultrasound for therapeutic purposes is growing. Besides established applications like lithotripsy, new applications like ultrasound in orthopedics or for the treatment of tumors arise. Therefore, new devices have to be developed which provide pressure waveforms and distributions in the focal zone specifically for the application. In this paper, a nonlinear full-wave simulation model is presented which predicts the therapeutically important characteristics of the generated ultrasound field for a given transducer and initial pressure signal. A nonlinear acoustic approximation in conservation form of the original hydrodynamic equations for ideal fluids rather than a wave equation provides the base for the nonlinear model. The equations are implemented with an explicit high-order finite-difference time-domain algorithm. The necessary coefficients are derived according to the dispersion relation preserving method. Simulation results are presented for two different therapeutic transducers: a self-focusing piezoelectric and one with reflector focusing. The computational results are validated by comparison with analytical solutions and measurements. An agreement of about 10% is observed between the simulation and experimental results.
Prediction of the bottomonium D-wave spectrum from full lattice QCD.
Daldrop, J O; Davies, C T H; Dowdall, R J
2012-03-09
We calculate the full spectrum of D-wave states in the Υ system in lattice QCD for the first time, by using an improved version of nonrelativistic QCD on coarse and fine "second-generation" gluon field configurations from the MILC Collaboration that include the effect of up, down, strange, and charm quarks in the sea. By taking the 2S-1S splitting to set the lattice spacing, we determine the (3)D2-1S splitting to 2.3% and find agreement with experiment. Our prediction of the fine structure relative to the (3)D2 gives the (3)D3 at 10.181(5) GeV and the (3)D1 at 10.147(6) GeV. We also discuss the overlap of (3)D1 operators with (3)S1 states.
2D full wave modeling for a synthetic Doppler backscattering diagnostic
Hillesheim, J. C.; Schmitz, L.; Kubota, S.; Rhodes, T. L.; Carter, T. A.; Holland, C.
2012-10-15
Doppler backscattering (DBS) is a plasma diagnostic used in tokamaks and other magnetic confinement devices to measure the fluctuation level of intermediate wavenumber (k{sub {theta}}{rho}{sub s}{approx} 1) density fluctuations and the lab frame propagation velocity of turbulence. Here, a synthetic DBS diagnostic is described, which has been used for comparisons between measurements in the DIII-D tokamak and predictions from nonlinear gyrokinetic simulations. To estimate the wavenumber range to which a Gaussian beam would be sensitive, a ray tracing code and a 2D finite difference, time domain full wave code are used. Experimental density profiles and magnetic geometry are used along with the experimental antenna and beam characteristics. An example of the effect of the synthetic diagnostic on the output of a nonlinear gyrokinetic simulation is presented.
Full wave modeling of ultrasonic NDE benchmark problems using Nyström method
NASA Astrophysics Data System (ADS)
Gurrala, Praveen; Chen, Kun; Song, Jiming; Roberts, Ron
2017-02-01
In this paper, we simulate some of the benchmark problems proposed by the World Federation of Nondestructive Evaluation Centers (WFNDEC) using a full wave simulation model based on accurate solutions to the boundary integral equations for ultrasonic scattering. Much of the previous work on modeling these problems relied on the Kirch-hoff approximation to find the scattered fields from defects. Here we instead use a numerical method, called the Nyström method, for finding the scattered fields more accurately by solving the boundary integral equations of scattering. We compare our model's predictions with both measurements and Kirchhoff approximation based models. We expect the presented results to serve as a validation of our model as well as a comparison between the Kirchhoff approximation and the Nyström method.
Analysis of guided wave propagation in a tapered composite panel
NASA Astrophysics Data System (ADS)
Wandowski, Tomasz; Malinowski, Pawel; Moll, Jochen; Radzienski, Maciej; Ostachowicz, Wieslaw
2015-03-01
Many studies have been published in recent years on Lamb wave propagation in isotropic and (multi-layered) anisotropic structures. In this paper, adiabatic wave propagation phenomenon in a tapered composite panel made out of glass fiber reinforced polymers (GFRP) will be considered. Such structural elements are often used e.g. in wind turbine blades and aerospace structures. Here, the wave velocity of each wave mode does not only change with frequency and the direction of wave propagation. It further changes locally due to the varying cross-section of the GFRP panel. Elastic waves were excited using a piezoelectric transducer. Full wave-field measurements using scanning Laser Doppler vibrometry have been performed. This approach allows the detailed analysis of elastic wave propagation in composite specimen with linearly changing thickness. It will be demonstrated here experimentally, that the wave velocity changes significantly due to the tapered geometry of the structure. Hence, this work motivates the theoretical and experimental analysis of adiabatic mode propagation for the purpose of Non-Destructive Testing and Structural Health Monitoring.
An Analysis of the Full-Floating Journal Bearing
NASA Technical Reports Server (NTRS)
Shaw, M C; Nussdorfer, T J , Jr
1947-01-01
An analysis of the operating characteristics of a full-floating journal bearing, a bearing in which a floating sleeve is located between the journal and bearing surfaces, is presented together with charts from which the performance of such bearings may be predicted. Examples are presented to illustrate the use of these charts and a limited number of experiments conducted upon a glass full-floating bearing are reported to verify some results of the analysis.
NASA Astrophysics Data System (ADS)
André, Frédéric; Lambot, Sébastien
2015-04-01
Accurate knowledge of the shallow soil properties is of prime importance in agricultural, hydrological and environmental engineering. During the last decade, numerous geophysical techniques, either invasive or resorting to proximal or remote sensing, have been developed and applied for quantitative characterization of soil properties. Amongst them, time domain reflectrometry (TDR) and frequency domain reflectometry (FDR) are recognized as standard techniques for the determination of soil dielectric permittivity and electrical conductivity, based on the reflected electromagnetic waves from a probe inserted into the soil. TDR data were first commonly analyzed in the time domain using methods considering only a part of the waveform information. Later, advancements have led to the possibility of analyzing the TDR signal through full-wave inverse modeling either in the time or the frequency domains. A major advantage of FDR compared to TDR is the possibility to increase the bandwidth, thereby increasing the information content of the data and providing more detailed characterization of the medium. Amongst the recent works in this field, Minet et al. (2010) developed a modeling procedure for processing FDR data based on an exact solution of Maxwell's equations for wave propagation in one-dimensional multilayered media. In this approach, the probe head is decoupled from the medium and is fully described by characteristic transfer functions. The authors successfully validated the method for homogeneous sand subject to a range of water contents. In the present study, we further validated the modelling approach using reference liquids with well-characterized frequency-dependent electrical properties. In addition, the FDR model was coupled with a dielectric mixing model to investigate the ability of retrieving water content, pore water electrical conductivity and sand porosity from inversion of FDR data acquired in sand subject to different water content levels. Finally, the
NASA Astrophysics Data System (ADS)
Kurz, Ph.; Förster, F.; Nordström, L.; Bihlmayer, G.; Blügel, S.
2004-01-01
The massively parallelized full-potential linearized augmented plane-wave bulk and film program FLEUR for first-principles calculations in the context of density functional theory was adapted to allow calculations of materials with complex magnetic structures—i.e., with noncollinear spin arrangements and incommensurate spin spirals. The method developed makes no shape approximation to the charge density and works with the continuous vector magnetization density in the interstitial and vacuum region and a collinear magnetization density in the spheres. We give an account of the implementation. Important technical aspects, such as the formulation of a constrained local moment method in a full-potential method that works with a vector magnetization density to deal with specific preselected nonstationary-state spin configurations, the inclusion of the generalized gradient approximation in a noncollinear framework, and the spin-relaxation method are discussed. The significance and validity of different approximations are investigated. We present examples to the various strategies to explore the magnetic ground state, metastable states, and magnetic phase diagrams by relaxation of spin arrangements or by performing calculations for constraint spin configurations to invest the functional dependence of the total energy and magnetic moment with respect to external parameters.
NASA Astrophysics Data System (ADS)
Wang, H.; Singh, S. C.; Ghosal, D.
2012-12-01
Seismic full waveform inversion is an emerging technique to determine fine-scale subsurface velocity structure. However, it requires a good starting velocity model, which is generally obtained using travel time tomography, to converge to a global minimum. Furthermore, the computing cost of full waveform inversion could be very high. In order to converge to a global solution, we have developed a combined full wave equation tomography (WET) and full waveform inversion (FWI) where the large and medium scale velocity is determined using full wave equation tomography first and then the fine-scale elastic parameters are inverted using full waveform inversion. WET and FWI both utilize full wavefield modeling, but differ on the definition of objective functions: WET aims to minimize L2-norm of cross-correlation synthetic and observed data, which is mainly sensitive to travel times, while FWI aims to optimize the L2-norm full waveform misfit, which is sensitive to both amplitudes and travel times of arrivals. Adjoint method is used to calculate the gradient for both methods efficiently. To compensate the energy loss due to wave propagation in the adjoint calculation and geometric limitation of survey, we apply an approximate Hessian preconditioning to the gradient. Further more, to stabilize WET, we precondition the time delay measures observed from cross-relation with maximum cross-correlation coefficients and perform tomographic model regularization to avoid local minimum. By exploring the band-limited feature of seismic wavefield, WET can provide better resolution than ray-based travel time tomography, and hence better suited for the FWI to converge to the true model, which provides very fine detail P and S-wave velocity. Both WET and WFI are based on the solution of full elastic wave equation and hence can model all types of wave present data. In order to reduce the computation cost and to invert seismic refraction arrivals first, we downward continue the streamer data
Characterization of an SRF gun: a 3D full wave simulation
Wang, E.; Ben-Zvi, I.; Wang, J.
2011-03-28
We characterized a BNL 1.3GHz half-cell SRF gun is tested for GaAs photocathode. The gun already was simulated several years ago via two-dimensional (2D) numerical codes (i.e., Superfish and Parmela) with and without the beam. In this paper, we discuss our investigation of its characteristics using a three dimensional (3D) full-wave code (CST STUDIO SUITE{trademark}).The input/pickup couplers are sited symmetrically on the same side of the gun at an angle of 180{sup o}. In particular, the inner conductor of the pickup coupler is considerably shorter than that of the input coupler. We evaluated the cross-talk between the beam (trajectory) and the signal on the input coupler compared our findings with published results based on analytical models. The CST STUDIO SUITE{trademark} also was used to predict the field within the cavity; particularly, a combination of transient/eigenmode solvers was employed to accurately construct the RF field for the particles, which also includes the effects of the couplers. Finally, we explored the beam's dynamics with a particle in cell (PIC) simulation, validated the results and compare them with 2D code result.
Crack Detection with Lamb Wave Wavenumber Analysis
NASA Technical Reports Server (NTRS)
Tian, Zhenhua; Leckey, Cara; Rogge, Matt; Yu, Lingyu
2013-01-01
In this work, we present our study of Lamb wave crack detection using wavenumber analysis. The aim is to demonstrate the application of wavenumber analysis to 3D Lamb wave data to enable damage detection. The 3D wavefields (including vx, vy and vz components) in time-space domain contain a wealth of information regarding the propagating waves in a damaged plate. For crack detection, three wavenumber analysis techniques are used: (i) two dimensional Fourier transform (2D-FT) which can transform the time-space wavefield into frequency-wavenumber representation while losing the spatial information; (ii) short space 2D-FT which can obtain the frequency-wavenumber spectra at various spatial locations, resulting in a space-frequency-wavenumber representation; (iii) local wavenumber analysis which can provide the distribution of the effective wavenumbers at different locations. All of these concepts are demonstrated through a numerical simulation example of an aluminum plate with a crack. The 3D elastodynamic finite integration technique (EFIT) was used to obtain the 3D wavefields, of which the vz (out-of-plane) wave component is compared with the experimental measurement obtained from a scanning laser Doppler vibrometer (SLDV) for verification purposes. The experimental and simulated results are found to be in close agreement. The application of wavenumber analysis on 3D EFIT simulation data shows the effectiveness of the analysis for crack detection. Keywords: : Lamb wave, crack detection, wavenumber analysis, EFIT modeling
Full-scale system impact analysis: Digital document storage project
NASA Technical Reports Server (NTRS)
1989-01-01
The Digital Document Storage Full Scale System can provide cost effective electronic document storage, retrieval, hard copy reproduction, and remote access for users of NASA Technical Reports. The desired functionality of the DDS system is highly dependent on the assumed requirements for remote access used in this Impact Analysis. It is highly recommended that NASA proceed with a phased, communications requirement analysis to ensure that adequate communications service can be supplied at a reasonable cost in order to validate recent working assumptions upon which the success of the DDS Full Scale System is dependent.
Performance analysis of a full-field and full-range swept-source OCT system
NASA Astrophysics Data System (ADS)
Krauter, J.; Boettcher, T.; Körner, K.; Gronle, M.; Osten, W.; Passilly, N.; Froehly, L.; Perrin, S.; Gorecki, C.
2015-09-01
In recent years, optical coherence tomography (OCT) became gained importance in medical disciplines like ophthalmology, due to its noninvasive optical imaging technique with micrometer resolution and short measurement time. It enables e. g. the measurement and visualization of the depth structure of the retina. In other medical disciplines like dermatology, histopathological analysis is still the gold standard for skin cancer diagnosis. The EU-funded project VIAMOS (Vertically Integrated Array-type Mirau-based OCT System) proposes a new type of OCT system combined with micro-technologies to provide a hand-held, low-cost and miniaturized OCT system. The concept is a combination of full-field and full-range swept-source OCT (SS-OCT) detection in a multi-channel sensor based on a micro-optical Mirau-interferometer array, which is fabricated by means of wafer fabrication. This paper presents the study of an experimental proof-of-concept OCT system as a one-channel sensor with bulk optics. This sensor is a Linnik-interferometer type with similar optical parameters as the Mirau-interferometer array. A commercial wavelength tunable light source with a center wavelength at 845nm and 50nm spectral bandwidth is used with a camera for parallel OCT A-Scan detection. In addition, the reference microscope objective lens of the Linnik-interferometer is mounted on a piezo-actuated phase-shifter. Phase-shifting interferometry (PSI) techniques are applied for resolving the conjugate complex artifact and consequently contribute to an increase of image quality and depth range. A suppression ratio of the complex conjugate term of 36 dB is shown and a system sensitivity greater than 96 dB could be measured.
Variational full wave calculation of fast wave current drive in DIII-D using the ALCYON code
Becoulet, A.; Moreau, D.
1992-04-01
Initial fast wave current drive simulations performed with the ALCYON code for the 60 MHz DIII-D experiment are presented. Two typical shots of the 1991 summer campaign were selected with magnetic field intensities of 1 and 2 teslas respectively. The results for the wave electromagnetic field in the plasma chamber are displayed. They exhibit a strong enrichment of the poloidal mode number m-spectrum which leads to the upshift of the parallel wavenumber, {kappa}{perpendicular}, and to the wave absorption. The m-spectrum is bounded when the local poloidal wavenumber reaches the Alfven wavenumber and the {kappa}{perpendicular} upshifts do not destroy the wave directionality. Linear estimations of the driven current are made. The current density profiles are found to be peaked and we find that about 88 kA can be driven in the 1 tesla/1.7 keV phase with 1.7 MW coupled to the electrons. In the 2 tesla/3.4 keV case, 47 kA are driven with a total power of 1.5 MW, 44% of which are absorbed on the hydrogen minority, through the second harmonic ion cyclotron resonance. The global efficiency is then 0.18 {times} 10{sup 19} A m{sup {minus}2}W{sup {minus}1} if one considers only the effective power going to the electrons.
AB 1007 Full Fuel Cycle Analysis (FFCA) Peer Review
Rice, D; Armstrong, D; Campbell, C; Lamont, A; Gallegos, G; Stewart, J; Upadhye, R
2007-01-19
LLNL is a participant of California's Advanced Energy Pathways (AEP) team funded by DOE (NETL). At the AEP technical review meeting on November 9, 2006. The AB 1007 FFCA team (Appendix A) requested LLNL participate in a peer review of the FFCA reports. The primary contact at the CEC was McKinley Addy. The following reports/presentations were received by LLNL: (1) Full Fuel Cycle Energy and Emissions Assumptions dated September 2006, TIAX; (2) Full Fuel cycle Assessment-Well to Tank Energy Inputs, Emissions, and Water Impacts dated December 2006, TIAX; and (3) Full Fuel Cycle Analysis Assessment dated October 12, 2006, TIAX.
Ishikawa, I; Katakura, K; Ogura, Y
1999-01-01
With a fixed gate width under the condition where the focus of an acoustic lens was set inside the sample, we varied signal taking-in time. Discrimination was made between differences in time required for an ultrasonic signal reflected from the sample to reach the acoustic lens. This process also enabled three types of images to be obtained separately: the surface reflection wave image, a combination of images based on the interference of the surface reflection wave with surface acoustic waves, and the surface acoustic wave image. Thus it was presumed that this process also would reveal the causes of image contrast and allow an easy interpretation of images. Furthermore, the image resolution was improved, because the surface acoustic wave image was drawn by an ultrasonic beam produced by full-circular surface acoustic wave excitation propagating toward the center converging concentrically; the theoretical resolution was 0.4 times the value of the surface acoustic wave wavelength lambda(R) and independent of the defocus value of the acoustic lens. Several kinds of samples were observed with this method. The results showed that the new method permitted observation of the internal structures of samples while offering new knowledge through the data reflecting the ultrasonic wave damping and scatter drawn on the display.
NASA Astrophysics Data System (ADS)
André, Frédéric; Jonard, Mathieu; Jonard, François; Lambot, Sébastien
2015-04-01
Decomposing litter accumulated at the soil surface in forest ecosystems play a major role in a series of ecosystem processes (soil carbon sequestration, nutrient release through decomposition, water retention, buffering of soil temperature variations, tree regeneration, population dynamics of ground vegetation and soil fauna, ...). Besides, the presence of litter is acknowledged to influence remote sensing radar data over forested areas and accurate quantification of litter radiative properties is essential for proper processing of these data. In these respects, ground-penetrating radar (GPR) presents particular interests, potentially allowing for fast and non-invasive characterization of organic layers with fine spatial and/or temporal resolutions as well as for providing detailed information on litter electrical properties which are required for modeling either active or passive microwave remote sensing data. We designed an experiment in order to analyze the backscattering from forest litter horizons and to investigate the potentialities of GPR for retrieving the physical properties of these horizons. For that purpose, we used an ultrawide band radar system connected to a transmitting and receiving horn antenna. The GPR data were processed resorting to full-wave inversion of the signal, through which antenna effects are accounted for. In a first step, GPR data were acquired over artificially reconstructed layers of three different beech litter types (i.e., (i) recently fallen litter with easily discernible plant organs (OL layer), (ii) fragmented litter in partial decomposition without entire plant organs (OF layer) and (iii) combination of OL and OF litter layers) and considering in each case a range of layer thicknesses. In a second step, so as to validate the adopted methodology in real natural conditions, GPR measurements were performed in situ along a transect crossing a wide range of litter properties in terms of thickness and composition through stands of
Full-wave Ambient Noise Tomography of Mt Rainier volcano, USA
NASA Astrophysics Data System (ADS)
Flinders, Ashton; Shen, Yang
2015-04-01
Mount Rainier towers over the landscape of western Washington (USA), ranking with Fuji-yama in Japan, Mt Pinatubo in the Philippines, and Mt Vesuvius in Italy, as one of the great stratovolcanoes of the world. Notwithstanding its picturesque stature, Mt Rainier is potentially the most devastating stratovolcano in North America, with more than 3.5 million people living beneath is shadow in the Seattle-Tacoma area. The primary hazard posed by the volcano is in the form of highly destructive debris flows (lahars). These lahars form when water and/or melted ice erode away and entrain preexisting volcanic sediment. At Mt Rainier these flows are often initiated by sector collapse of the volcano's hydrothermally rotten flanks and compounded by Mt Rainier's extensive snow and glacial ice coverage. It is therefore imperative to ascertain the extent of the volcano's summit hydrothermal alteration, and determine areas prone to collapse. Despite being one of the sixteen volcanoes globally designated by the International Association of Volcanology and Chemistry of the Earth's Interior as warranting detailed and focused study, Mt Rainier remains enigmatic both in terms of the shallow internal structure and the degree of summit hydrothermal alteration. We image this shallow internal structure and areas of possible summit alteration using ambient noise tomography. Our full waveform forward modeling includes high-resolution topography allowing us to accuratly account for the effects of topography on the propagation of short-period Rayleigh waves. Empirical Green's functions were extracted from 80 stations within 200 km of Mt Rainier, and compared with synthetic greens functions over multiple frequency bands from 2-28 seconds.
Full Information Item Factor Analysis of the FCI
NASA Astrophysics Data System (ADS)
Hagedorn, Eric
2010-02-01
Traditional factor analytical methods, principal factors or principal components analysis, are inappropriate techniques for analyzing dichotomously scored responses to standardized tests or concept inventories because they lead to artifactual factors often referred to as ``difficulty factors.'' Full information item factor analysis (Bock, Gibbons and Muraki, 1988) based on Thurstone's multiple factor model and calculated using marginal maximum likelihood estimation, is an appropriate technique for such analyses. Force Concept Inventory (Hestenes, Wells and Swackhamer, 1992) data from 1582 university students completing an introductory physics course, was analyzed using the full information item factor analysis software TESTFACT v. 4. Analyzing the statistical significance of successive factors added to the model, using chi-squared statistics, led to a six factor model interpretable in terms of the conceptual dimensions of the FCI. )
Full-wave theory of a quasi-optical launching system for lower-hybrid waves: Preliminary results
Cincotti, G.; Gori, F.; Santarsiero, M.; Serrecchia, R. ); Frezza, F.; Schettini, G. ); Santini, F. )
1994-10-15
Numerical studies on the use of an advanced launcher to couple lower-hybrid waves to a plasma, for current drive in tokamaks, are currently under development. The study of the coupling has been carried out in a rigorous way, through the solution of the scattering from cylinders with parallel axes in the presence of a plane of discontinuity for electromagnetic constants. We present the general features of the proposed method together with preliminary results on launched spectra and coupled power.
Digital techniques for ULF wave polarization analysis
NASA Technical Reports Server (NTRS)
Arthur, C. W.
1979-01-01
Digital power spectral and wave polarization analysis are powerful techniques for studying ULF waves in the earth's magnetosphere. Four different techniques for using the spectral matrix to perform such an analysis have been presented in the literature. Three of these techniques are similar in that they require transformation of the spectral matrix to the principal axis system prior to performing the polarization analysis. The differences in the three techniques lie in the manner in which determine this transformation. A comparative study of these three techniques using both simulated and real data has shown them to be approximately equal in quality of performance. The fourth technique does not require transformation of the spectral matrix. Rather, it uses the measured spectral matrix and state vectors for a desired wave type to design a polarization detector function in the frequency domain. The design of various detector functions and their application to both simulated and real data will be presented.
NASA Astrophysics Data System (ADS)
Schumacher, F.; Friederich, W.
2015-12-01
We present the modularized software package ASKI which is a flexible and extendable toolbox for seismic full waveform inversion (FWI) as well as sensitivity or resolution analysis operating on the sensitivity matrix. It utilizes established wave propagation codes for solving the forward problem and offers an alternative to the monolithic, unflexible and hard-to-modify codes that have typically been written for solving inverse problems. It is available under the GPL at www.rub.de/aski. The Gauss-Newton FWI method for 3D-heterogeneous elastic earth models is based on waveform sensitivity kernels and can be applied to inverse problems at various spatial scales in both Cartesian and spherical geometries. The kernels are derived in the frequency domain from Born scattering theory as the Fréchet derivatives of linearized full waveform data functionals, quantifying the influence of elastic earth model parameters on the particular waveform data values. As an important innovation, we keep two independent spatial descriptions of the earth model - one for solving the forward problem and one representing the inverted model updates. Thereby we account for the independent needs of spatial model resolution of forward and inverse problem, respectively. Due to pre-integration of the kernels over the (in general much coarser) inversion grid, storage requirements for the sensitivity kernels are dramatically reduced.ASKI can be flexibly extended to other forward codes by providing it with specific interface routines that contain knowledge about forward code-specific file formats and auxiliary information provided by the new forward code. In order to sustain flexibility, the ASKI tools must communicate via file output/input, thus large storage capacities need to be accessible in a convenient way. Storing the complete sensitivity matrix to file, however, permits the scientist full manual control over each step in a customized procedure of sensitivity/resolution analysis and full
The Data Analysis in Gravitational Wave Detection
NASA Astrophysics Data System (ADS)
Xiao-ge, Wang; Lebigot, Eric; Zhi-hui, Du; Jun-wei, Cao; Yun-yong, Wang; Fan, Zhang; Yong-zhi, Cai; Mu-zi, Li; Zong-hong, Zhu; Jin, Qian; Cong, Yin; Jian-bo, Wang; Wen, Zhao; Yang, Zhang; Blair, David; Li, Ju; Chun-nong, Zhao; Lin-qing, Wen
2017-01-01
Gravitational wave (GW) astronomy based on the GW detection is a rising interdisciplinary field, and a new window for humanity to observe the universe, followed after the traditional astronomy with the electromagnetic waves as the detection means, it has a quite important significance for studying the origin and evolution of the universe, and for extending the astronomical research field. The appearance of laser interferometer GW detector has opened a new era of GW detection, and the data processing and analysis of GWs have already been developed quickly around the world, to provide a sharp weapon for the GW astronomy. This paper introduces systematically the tool software that commonly used for the data analysis of GWs, and discusses in detail the basic methods used in the data analysis of GWs, such as the time-frequency analysis, composite analysis, pulsar timing analysis, matched filter, template, χ2 test, and Monte-Carlo simulation, etc.
Full-wave Moment Tensor and Tomographic Inversions Based on 3D Strain Green Tensor
2010-01-31
G. Jahnke, Wave propagation in 3D spherical sections: effects of subduction zones , Phys. Earth Planet. Inter., 132, 219-234, 2002. Komastitsch, D...is at scales smaller than the Fresnel zone . For example, a 1-Hz P/Pn wave recorded by a receiver ~1000 km from the source has a Fresnel zone width...approach, Eos Trans. AGU, 89(53), Fall Meet. Suppl., abstract T11E-06 Invited, 2008b. Sigloch, K., N. McQuarrie, G. Nolet, Two-stage subduction
Integrated inversion using combined wave-equation tomography and full waveform inversion
NASA Astrophysics Data System (ADS)
Wang, Haiyang; Singh, Satish C.; Calandra, Henri
2014-07-01
Wave-equation tomography (WT) and full waveform inversion (FWI) are combined through a hybrid misfit function to estimate high-resolution subsurface structures starting from a poorly constrained initial velocity model. Both methods share the same wavefield forward modelling and inversion schemes, while they differ only on the ways to calculate misfit functions and hence the ways to sample in the model space. Aiming at minimizing the cross-correlation phase delay between synthetic and real data, WT can be used to retrieve the long- and middle-wavelength model components, which are essential to FWI. Compared to ray-based traveltime tomography that is based on asymptotic high-frequency approximation, WT provides a better resolution by exploring the band-limited feature of seismic wavefield. On the other hand, FWI is capable of resolving the short-wavelength model component, complementing the WT. In this study, we apply WT to surface first-arrival refraction data, and apply FWI to both refraction and reflection data. We assign adaptive weights to the two different misfit measurements and build a progressive inversion strategy. To illustrate the advantage of our strategy over conventional `ray tomography + FWI' approach, we show in a synthetic lens test that WT can provide extra subsurface information that is critical for a successful FWI application. To further show the efficiency, we test our strategy on the 2-D Marmousi model where satisfactory inversion results are achieved without much manual intervention. Finally, we apply the inversion strategy to a deep-water seismic data set acquired offshore Sumatra with a 12-km-long streamer. In order to alleviate several practical problems posed by the deep-water setting, we apply downward continuation (DC) to generate a virtual ocean bottom experiment data set prior to inversion. The new geometry after DC boosts up the shallow refractions, as well as avoiding cumbersome modelling through the thick water column, thus
Tsujii, N.; Porkolab, M.; Bonoli, P. T.; Edlund, E. M.; Ennever, P. C.; Lin, Y.; Wright, J. C.; Wukitch, S. J.; Jaeger, E. F.; Green, D. L.; Harvey, R. W.
2015-08-15
Mode conversion of fast waves in the ion cyclotron range of frequencies (ICRF) is known to result in current drive and flow drive under optimised conditions, which may be utilized to control plasma profiles and improve fusion plasma performance. To describe these processes accurately in a realistic toroidal geometry, numerical simulations are essential. Quantitative comparison of these simulations and the actual experimental measurements is important to validate their predictions and to evaluate their limitations. The phase contrast imaging (PCI) diagnostic has been used to directly detect the ICRF waves in the Alcator C-Mod tokamak. The measurements have been compared with full-wave simulations through a synthetic diagnostic technique. Recently, the frequency response of the PCI detector array on Alcator C-Mod was recalibrated, which greatly improved the comparison between the measurements and the simulations. In this study, mode converted waves for D-{sup 3}He and D-H plasmas with various ion species compositions were re-analyzed with the new calibration. For the minority heating cases, self-consistent electric fields and a minority ion distribution function were simulated by iterating a full-wave code and a Fokker-Planck code. The simulated mode converted wave intensity was in quite reasonable agreement with the measurements close to the antenna, but discrepancies remain for comparison at larger distances.
Wave analysis of the evolution of a single wave packet in supersonic boundary layer
NASA Astrophysics Data System (ADS)
Yermolaev, Yury G.; Yatskikh, Aleksey A.; Kosinov, Alexander D.; Semionov, Nickolay V.
2016-10-01
The evolution of the artificial wave packet in laminar flat-plate boundary layer was experimentally studied by hot-wire measurements at M=2. The localized disturbances were generated by pulse glow discharge. The wave analysis of evolution of wave packet was provided. It was found, that the most unstable waves are oblique, that consistent with results of linear theory.
Gradient Index Devices for the Full Control of Elastic Waves in Plates
Jin, Yabin; Torrent, Daniel; Pennec, Yan; Pan, Yongdong; Djafari-Rouhani, Bahram
2016-01-01
In this work, we present a method for the design of gradient index devices for elastic waves in plates. The method allows the design of devices to control the three fundamental modes, despite the fact that their dispersion relation is managed by different elastic constants. It is shown that by means of complex graded phononic crystals and thickness variations it is possible to independently design the three refractive indexes of these waves, allowing therefore their simultaneous control. The effective medium theory required for this purpose is presented, and the method is applied to the design of the Luneburg and Maxwell lenses as well as to the design of a flat gradient index lens. Finally, numerical simulations are used to demonstrate the performance of the method in a broadband frequency region. PMID:27075601
Gradient Index Devices for the Full Control of Elastic Waves in Plates.
Jin, Yabin; Torrent, Daniel; Pennec, Yan; Pan, Yongdong; Djafari-Rouhani, Bahram
2016-04-14
In this work, we present a method for the design of gradient index devices for elastic waves in plates. The method allows the design of devices to control the three fundamental modes, despite the fact that their dispersion relation is managed by different elastic constants. It is shown that by means of complex graded phononic crystals and thickness variations it is possible to independently design the three refractive indexes of these waves, allowing therefore their simultaneous control. The effective medium theory required for this purpose is presented, and the method is applied to the design of the Luneburg and Maxwell lenses as well as to the design of a flat gradient index lens. Finally, numerical simulations are used to demonstrate the performance of the method in a broadband frequency region.
Huang, Chao; Wang, Kun; Nie, Liming; Wang, Lihong V; Anastasio, Mark A
2013-06-01
Existing approaches to image reconstruction in photoacoustic computed tomography (PACT) with acoustically heterogeneous media are limited to weakly varying media, are computationally burdensome, and/or cannot effectively mitigate the effects of measurement data incompleteness and noise. In this work, we develop and investigate a discrete imaging model for PACT that is based on the exact photoacoustic (PA) wave equation and facilitates the circumvention of these limitations. A key contribution of the work is the establishment of a procedure to implement a matched forward and backprojection operator pair associated with the discrete imaging model, which permits application of a wide-range of modern image reconstruction algorithms that can mitigate the effects of data incompleteness and noise. The forward and backprojection operators are based on the k-space pseudospectral method for computing numerical solutions to the PA wave equation in the time domain. The developed reconstruction methodology is investigated by use of both computer-simulated and experimental PACT measurement data.
Comparative dynamic analysis of the full Grossman model.
Ried, W
1998-08-01
The paper applies the method of comparative dynamic analysis to the full Grossman model. For a particular class of solutions, it derives the equations implicitly defining the complete trajectories of the endogenous variables. Relying on the concept of Frisch decision functions, the impact of any parametric change on an endogenous variable can be decomposed into a direct and an indirect effect. The focus of the paper is on marginal changes in the rate of health capital depreciation. It also analyses the impact of either initial financial wealth or the initial stock of health capital. While the direction of most effects remains ambiguous in the full model, the assumption of a zero consumption benefit of health is sufficient to obtain a definite for any direct or indirect effect.
Full 3D dispersion curve solutions for guided waves in generally anisotropic media
NASA Astrophysics Data System (ADS)
Hernando Quintanilla, F.; Lowe, M. J. S.; Craster, R. V.
2016-02-01
Dispersion curves of guided waves provide valuable information about the physical and elastic properties of waves propagating within a given waveguide structure. Algorithms to accurately compute these curves are an essential tool for engineers working in non-destructive evaluation and for scientists studying wave phenomena. Dispersion curves are typically computed for low or zero attenuation and presented in two or three dimensional plots. The former do not always provide a clear and complete picture of the dispersion loci and the latter are very difficult to obtain when high values of attenuation are involved and arbitrary anisotropy is considered in single or multi-layered systems. As a consequence, drawing correct and reliable conclusions is a challenging task in the modern applications that often utilize multi-layered anisotropic viscoelastic materials. These challenges are overcome here by using a spectral collocation method (SCM) to robustly find dispersion curves in the most complicated cases of high attenuation and arbitrary anisotropy. Solutions are then plotted in three-dimensional frequency-complex wavenumber space, thus gaining much deeper insight into the nature of these problems. The cases studied range from classical examples, which validate this approach, to new ones involving materials up to the most general triclinic class for both flat and cylindrical geometry in multi-layered systems. The apparent crossing of modes within the same symmetry family in viscoelastic media is also explained and clarified by the results. Finally, the consequences of the centre of symmetry, present in every crystal class, on the solutions are discussed.
All-Sky Search for Periodic Gravitational Waves in the Full S5 LIGO Data
NASA Technical Reports Server (NTRS)
Abadie, J.; Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M.; Accadia, T.; Acernese, F.; Adams, C.; Adhikari, R.; Affeldt, C.; Ajith, P.; Allen, B.; Allen, G. S.; Amador Ceron, E.; Amariutei, D.; Amin, R. S.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Arain, M. S.; Araya, M. C.; Aston, S. M.; Blackburn, L.; Camp, J. B.; Cannizzo, J.
2011-01-01
We report on an all-sky search for periodic gravitational waves in the frequency band 50-800 Hz and with the frequency time derivative in the range of 0 through -6 x 10(exp -9) Hz/s. Such a signal could be produced by a nearby spinning and slightly non-axisymmetric isolated neutron star in our galaxy. After recent improvements in the search program that yielded a 10x increase in computational efficiency, we have searched in two years of data. collected during LIGO's fifth science run and have obtained the most sensitive all-sky upper limits on gravitational wave strain to date. Near 150 Hz our upper limit on worst-case linearly polarized strain amplitude h(sub 0) is 1 x 10(exp -24), while at the high end of our frequency ra.nge we achieve a worst-case upper limit of 3.8 x 10(exp -24) for all polarizations and sky locations. These results constitute a factor of two improvement upop. previously published data. A new detection pipeline utilizing a Loosely Coherent algorithm was able to follow up weaker outliers, increasing the volume of space where signals can be detected by a factor of 10, but has not revealed any gravitational wave signals. The pipeline has been tested for robustness with respect to deviations from the model of an isolated neutron star, such as caused by a low-mass or long.period binary companion.
Acoustic Emission and Guided Wave Monitoring of Fatigue Crack Growth on a Full Pipe Specimen
Meyer, Ryan M.; Cumblidge, Stephen E.; Ramuhalli, Pradeep; Watson, Bruce E.; Doctor, Steven R.; Bond, Leonard J.
2011-05-06
Continuous on-line monitoring of active and passive systems, structures and components in nuclear power plants will be critical to extending the lifetimes of nuclear power plants in the US beyond 60 years. Acoustic emission and guided ultrasonic waves are two tools for continuously monitoring passive systems, structures and components within nuclear power plants and are the focus of this study. These tools are used to monitor fatigue damage induced in a SA 312 TP304 stainless steel pipe specimen. The results of acoustic emission monitoring indicate that crack propagation signals were not directly detected. However, acoustic emission monitoring exposed crack formation prior to visual confirmation through the detection of signals caused by crack closure friction. The results of guided ultrasonic wave monitoring indicate that this technology is sensitive to the presence and size of cracks. The sensitivity and complexity of GUW signals is observed to vary with respect to signal frequency and path traveled by the guided ultrasonic wave relative to the crack orientation.
Analysis and Optimization of "Full-Length" Diodes
Schock, Alfred
2012-01-19
A method of analyzing the axial variation of the heat generation rate, temperature, voltage, current density and emitter heat flux in a thermionic converter is described. The method is particularly useful for the case of "long" diodes, each extending over the full length of the reactor core. For a given diode geometry and fuel distribution, the analysis combines a nuclear solution of the axial fission density profile with the iterative solution of four differential equations representing the thermal, electrical, and thermionic interactions within the diode. The digital computer program developed to solve these equations can also perform a design optimization with respect to lead resistance, load voltage, and emitter thickness, for a specified maximum emitter temperature. Typical results are presented, and the use of this analysis for predicting the diode operating characteristics is illustrated.
2014-04-30
105. Shen, Y., et al., 2013, Construction of a nested, global empirical Green’s tensor database, Seismological Society of America meeting, Salt...W. Zhang, 2010, Full-wave ambient noise tomography of the northern Cascadia, SSA meeting (abstract), Seismological Research Letters, 81, 300. Shen
Bertelli, N.; Jaeger, E. F.; Hosea, J. C.; Phillips, C. K.; Berry, L.; Bonoli, P. T.; Gerhardt, S. P.; Green, D.; LeBlanc, B.; Perkins, R. J.; Qin, C. M.; Pinsker, R. I.; Prater, R.; Ryan, P. M.; Taylor, G.; Valeo, E. J.; Wilson, J. R.; Wright, J. C.; Zhang, X. J.
2015-12-17
Here, several experiments on different machines and in different fast wave (FW) heating regimes, such as hydrogen minority heating and high harmonic fast waves (HHFW), have found strong interaction between radio-frequency (RF) waves and the scrape-off layer (SOL) region. This paper examines the propagation and the power loss in the SOL by using the full wave code AORSA, in which the edge plasma beyond the last closed flux surface (LCFS) is included in the solution domain and a collisional damping parameter is used as a proxy to represent the real, and most likely nonlinear, damping processes. 2D and 3D AORSA results for the National Spherical Torus eXperiment (NSTX) have shown a strong transition to higher SOL power losses (driven by the RF field) when the FW cut-off is removed from in front of the antenna by increasing the edge density. Here, full wave simulations have been extended for 'conventional' tokamaks with higher aspect ratios, such as the DIII-D, Alcator C-Mod, and EAST devices. DIII-D results in HHFW regime show similar behavior found in NSTX and NSTX-U, consistent with previous DIII-D experimental observations. In contrast, a different behavior has been found for C-Mod and EAST, which operate in the minority heating regime.
Bertelli, N.; Jaeger, E. F.; Hosea, J. C.; ...
2015-12-17
Here, several experiments on different machines and in different fast wave (FW) heating regimes, such as hydrogen minority heating and high harmonic fast waves (HHFW), have found strong interaction between radio-frequency (RF) waves and the scrape-off layer (SOL) region. This paper examines the propagation and the power loss in the SOL by using the full wave code AORSA, in which the edge plasma beyond the last closed flux surface (LCFS) is included in the solution domain and a collisional damping parameter is used as a proxy to represent the real, and most likely nonlinear, damping processes. 2D and 3D AORSAmore » results for the National Spherical Torus eXperiment (NSTX) have shown a strong transition to higher SOL power losses (driven by the RF field) when the FW cut-off is removed from in front of the antenna by increasing the edge density. Here, full wave simulations have been extended for 'conventional' tokamaks with higher aspect ratios, such as the DIII-D, Alcator C-Mod, and EAST devices. DIII-D results in HHFW regime show similar behavior found in NSTX and NSTX-U, consistent with previous DIII-D experimental observations. In contrast, a different behavior has been found for C-Mod and EAST, which operate in the minority heating regime.« less
Full-spectrum analysis of natural gamma-ray spectra.
Hendriks, P H; Limburg, J; de Meijer, R J
2001-01-01
In this paper, a new system to measure natural gamma-radiation in situ will be presented. This system combines a high-efficiency BGO scintillation detector with full-spectrum data analysis (FSA). This technique uses the (nearly) full spectral shape and the so-called 'standard spectra' to calculate the activity concentrations of 40K, 232Th and 238U present in a geological matrix (sediment, rock, etc.). We describe the FSA and the determination of the standard spectra. Standard spectra are constructed for various geometries and a comparison in intensity and shape will be made. The performance of such a system has been compared to a more traditional system, consisting of a NaI detector in combination with the 'windows' analysis. For count rates typically encountered in field experiments, the same accuracy is obtained 10-20 times faster using the new system. This allows for shorter integration times and hence shorter measurements or a better spatial resolution. The applicability of such a system will be illustrated via an example of an airborne experiment in which the new system produced results comparable to those of much larger traditional systems. This paper will conclude with a discussion of the current status of the system and an outlook for future research.
Analysis of critically refracted longitudinal waves
NASA Astrophysics Data System (ADS)
Pei, Ning; Bond, Leonard J.
2015-03-01
Fabrication processes, such as, welding, forging, and rolling can induce residual stresses in metals that will impact product performance and phenomena such as cracking and corrosion. To better manage residual stress tools are needed to map their distribution. The critically refracted ultrasonic longitudinal (LCR) wave is one such approach that has been used for residual stress characterization. It has been shown to be sensitive to stress and less sensitive to the effects of the texture of the material. Although the LCR wave is increasingly widely applied, the factors that influence the formation of the LCR beam are seldom discussed. This paper reports a numerical model used to investigate the transducers' parameters that can contribute to the directionality of the LCR wave and hence enable performance optimization when used for industrial applications. An orthogonal test method is used to study the transducer parameters which influence the LCR wave beams. This method provides a design tool that can be used to study and optimize multiple parameter experiments and it can identify which parameter or parameters are of most significance. The simulation of the sound field in a 2-D "water-steel" model is obtained using a Spatial Fourier Analysis method. The effects of incident angle, standoff, the aperture and the center frequency of the transducer were studied. Results show that the aperture of the transducer, the center frequency and the incident angle are the most important factors in controlling the directivity of the resulting LCR wave fields.
Analysis of critically refracted longitudinal waves
Pei, Ning Bond, Leonard J.
2015-03-31
Fabrication processes, such as, welding, forging, and rolling can induce residual stresses in metals that will impact product performance and phenomena such as cracking and corrosion. To better manage residual stress tools are needed to map their distribution. The critically refracted ultrasonic longitudinal (LCR) wave is one such approach that has been used for residual stress characterization. It has been shown to be sensitive to stress and less sensitive to the effects of the texture of the material. Although the LCR wave is increasingly widely applied, the factors that influence the formation of the LCR beam are seldom discussed. This paper reports a numerical model used to investigate the transducers' parameters that can contribute to the directionality of the LCR wave and hence enable performance optimization when used for industrial applications. An orthogonal test method is used to study the transducer parameters which influence the LCR wave beams. This method provides a design tool that can be used to study and optimize multiple parameter experiments and it can identify which parameter or parameters are of most significance. The simulation of the sound field in a 2-D 'water-steel' model is obtained using a Spatial Fourier Analysis method. The effects of incident angle, standoff, the aperture and the center frequency of the transducer were studied. Results show that the aperture of the transducer, the center frequency and the incident angle are the most important factors in controlling the directivity of the resulting LCR wave fields.
Terrestrial detector for low-frequency gravitational waves based on full tensor measurement
NASA Astrophysics Data System (ADS)
Paik, H. J.; Moody, M. V.; Griggs, C. E.; Lee, H. M.; Majorana, E.
2016-05-01
Two serious obstacles in constructing terrestrial gravitational wave (GW) detectors that can resolve low-frequency signals (≤ 10 Hz) are seismic and Newtonian noises. Here we describe a new detector concept by adopting new measurement techniques and configurations to overcome the present low-frequency barrier due to these noises. Six magnetically levitated superconducting test masses, widely separated along three orthogonal axes, each with three degrees of freedom, constitute a tensor GW detector. The tensor outputs could be combined to better reject the Newtonian noise. Unlike current two-dimensional detectors, a single tensor detector is able to determine the polarization of GWs and the direction to sources on its own.
Bayesian analysis on gravitational waves and exoplanets
NASA Astrophysics Data System (ADS)
Deng, Xihao
Attempts to detect gravitational waves using a pulsar timing array (PTA), i.e., a collection of pulsars in our Galaxy, have become more organized over the last several years. PTAs act to detect gravitational waves generated from very distant sources by observing the small and correlated effect the waves have on pulse arrival times at the Earth. In this thesis, I present advanced Bayesian analysis methods that can be used to search for gravitational waves in pulsar timing data. These methods were also applied to analyze a set of radial velocity (RV) data collected by the Hobby- Eberly Telescope on observing a K0 giant star. They confirmed the presence of two Jupiter mass planets around a K0 giant star and also characterized the stellar p-mode oscillation. The first part of the thesis investigates the effect of wavefront curvature on a pulsar's response to a gravitational wave. In it we show that we can assume the gravitational wave phasefront is planar across the array only if the source luminosity distance " 2piL2/lambda, where L is the pulsar distance to the Earth (˜ kpc) and lambda is the radiation wavelength (˜ pc) in the PTA waveband. Correspondingly, for a point gravitational wave source closer than ˜ 100 Mpc, we should take into account the effect of wavefront curvature across the pulsar-Earth line of sight, which depends on the luminosity distance to the source, when evaluating the pulsar timing response. As a consequence, if a PTA can detect a gravitational wave from a source closer than ˜ 100 Mpc, the effects of wavefront curvature on the response allows us to determine the source luminosity distance. The second and third parts of the thesis propose a new analysis method based on Bayesian nonparametric regression to search for gravitational wave bursts and a gravitational wave background in PTA data. Unlike the conventional Bayesian analysis that introduces a signal model with a fixed number of parameters, Bayesian nonparametric regression sets
Huang, Chao; Wang, Kun; Nie, Liming; Wang, Lihong V.; Anastasio, Mark A.
2014-01-01
Existing approaches to image reconstruction in photoacoustic computed tomography (PACT) with acoustically heterogeneous media are limited to weakly varying media, are computationally burdensome, and/or cannot effectively mitigate the effects of measurement data incompleteness and noise. In this work, we develop and investigate a discrete imaging model for PACT that is based on the exact photoacoustic (PA) wave equation and facilitates the circumvention of these limitations. A key contribution of the work is the establishment of a procedure to implement a matched forward and backprojection operator pair associated with the discrete imaging model, which permits application of a wide-range of modern image reconstruction algorithms that can mitigate the effects of data incompleteness and noise. The forward and backprojection operators are based on the k-space pseudospectral method for computing numerical solutions to the PA wave equation in the time domain. The developed reconstruction methodology is investigated by use of both computer-simulated and experimental PACT measurement data. PMID:23529196
Full Transcriptome Analysis of Early Dorsoventral Patterning in Zebrafish
Horváth, Balázs; Molnár, János; Nagy, István; Tóth, Gábor; Wilson, Stephen W.; Varga, Máté
2013-01-01
Understanding the molecular interactions that lead to the establishment of the major body axes during embryogenesis is one of the main goals of developmental biology. Although the past two decades have revolutionized our knowledge about the genetic basis of these patterning processes, the list of genes involved in axis formation is unlikely to be complete. In order to identify new genes involved in the establishment of the dorsoventral (DV) axis during early stages of zebrafish embryonic development, we employed next generation sequencing for full transcriptome analysis of normal embryos and embryos lacking overt DV pattern. A combination of different statistical approaches yielded 41 differentially expressed candidate genes and we confirmed by in situ hybridization the early dorsal expression of 32 genes that are transcribed shortly after the onset of zygotic transcription. Although promoter analysis of the validated genes suggests no general enrichment for the binding sites of early acting transcription factors, most of these genes carry “bivalent” epigenetic histone modifications at the time when zygotic transcription is initiated, suggesting a “poised” transcriptional status. Our results reveal some new candidates of the dorsal gene regulatory network and suggest that a plurality of the earliest upregulated genes on the dorsal side have a role in the modulation of the canonical Wnt pathway. PMID:23922899
Full-wave simulation of a three-dimensional metamaterial prism
Basilio, Lorena I.; Langston, William L.; Warne, Larry K.; Johnson, William A.; Sinclair, Michael B.
2015-01-23
In our article, a negative-index metamaterial prism based on a composite unit cell containing a split-ring resonator and a z-dipole is designed and simulated. The design approach combines simulations of a single unit cell to identify the appropriate cell design (yielding the desired negative-index behavior) together with subcell modeling (which simplifies the mesh representation of the resonator geometry and allows for a larger number of resonator cells to be handled). Furthermore, to describe the methodology used in designing a n = -1 refractive index prism, our results include the effective-medium parameters, the far-field scattered patterns, and the near-zone field distributions corresponding to a normally incident plane-wave excitation of the prism.
Full-wave simulation of a three-dimensional metamaterial prism
Basilio, Lorena I.; Langston, William L.; Warne, Larry K.; ...
2015-01-23
In our article, a negative-index metamaterial prism based on a composite unit cell containing a split-ring resonator and a z-dipole is designed and simulated. The design approach combines simulations of a single unit cell to identify the appropriate cell design (yielding the desired negative-index behavior) together with subcell modeling (which simplifies the mesh representation of the resonator geometry and allows for a larger number of resonator cells to be handled). Furthermore, to describe the methodology used in designing a n = -1 refractive index prism, our results include the effective-medium parameters, the far-field scattered patterns, and the near-zone field distributionsmore » corresponding to a normally incident plane-wave excitation of the prism.« less
Wave energy budget analysis in the Earth's radiation belts uncovers a missing energy.
Artemyev, A V; Agapitov, O V; Mourenas, D; Krasnoselskikh, V V; Mozer, F S
2015-05-15
Whistler-mode emissions are important electromagnetic waves pervasive in the Earth's magnetosphere, where they continuously remove or energize electrons trapped by the geomagnetic field, controlling radiation hazards to satellites and astronauts and the upper-atmosphere ionization or chemical composition. Here, we report an analysis of 10-year Cluster data, statistically evaluating the full wave energy budget in the Earth's magnetosphere, revealing that a significant fraction of the energy corresponds to hitherto generally neglected very oblique waves. Such waves, with 10 times smaller magnetic power than parallel waves, typically have similar total energy. Moreover, they carry up to 80% of the wave energy involved in wave-particle resonant interactions. It implies that electron heating and precipitation into the atmosphere may have been significantly under/over-valued in past studies considering only conventional quasi-parallel waves. Very oblique waves may turn out to be a crucial agent of energy redistribution in the Earth's radiation belts, controlled by solar activity.
Stress formulation in the all-electron full-potential linearized augmented plane wave method
NASA Astrophysics Data System (ADS)
Nagasako, Naoyuki; Oguchi, Tamio
2012-02-01
Stress formulation in the linearlized augmented plane wave (LAPW) method has been proposed in 2002 [1] as an extension of the force formulation in the LAPW method [2]. However, pressure calculations only for Al and Si were reported in Ref.[1] and even now stress calculations have not yet been fully established in the LAPW method. In order to make it possible to efficiently relax lattice shape and atomic positions simultaneously and to precisely evaluate the elastic constants in the LAPW method, we reformulate stress formula in the LAPW method with the Soler-Williams representation [3]. Validity of the formulation is tested by comparing the pressure obtained as the trace of stress tensor with that estimated from total energies for a wide variety of material systems. Results show that pressure is estimated within the accuracy of less than 0.1 GPa. Calculations of the shear elastic constant show that the shear components of the stress tensor are also precisely computed with the present formulation [4].[4pt] [1] T. Thonhauser et al., Solid State Commun. 124, 275 (2002).[0pt] [2] R. Yu et al., Phys. Rev. B 43, 6411 (1991).[0pt] [3] J. M. Soler and A. R. Williams, Phys. Rev. B 40, 1560 (1989).[0pt] [4] N. Nagasako and T. Oguchi, J. Phys. Soc. Jpn. 80, 024701 (2011).
Three-dimensional plane-wave full-band quantum transport using empirical pseudopotentials
NASA Astrophysics Data System (ADS)
Fang, Jingtian; Vandenberghe, William; Fischetti, Massimo
2015-03-01
We study theoretically the ballistic performance of future sub-5 nm Field-Effect Transistors (FETs) using an atomistic quantum transport formalism based on empirical pseudopotentials, with armchair Graphene NanoRibbons (aGNRs), Silicon NanoWires (SiNWs) and zigzag Carbon NanoTubes (zCNTs) as channel structures. Due to the heavy computational burden from the plane-wave basis set, we restrict our study to ultrasmall devices, characterized by 5 nm channel lengths and 0.7 nm × 0.7 nm cross-sectional areas. Band structure calculations show that aGNRs have an oscillating chirality-dependent band gap. AGNRs with dimer lines N=3p+1 have large band gaps and aGNRFETs show promising device performance in terms of high Ion/Ioff, small drain-induced barrier lowering and limited short channel effects due to their very thin body and associated excellent electrostatics control. N=3p+2 aGNRs have small band gaps and band-to-band tunneling generates a large current at high bias. We also discuss spurious solutions introduced by the envelope function approximation. Device characteristics of SiNWFETs and zCNTFETs are compared to aGNRFETs as well. We acknowledge the support of Nanoelectronics Research Initiatives's (NRI's) Southwest Academy of Nanoelectronics (SWAN).
Mynard, Jonathan P; Smolich, Joseph J
2016-04-15
Wave intensity analysis provides detailed insights into factors influencing hemodynamics. However, wave intensity is not a conserved quantity, so it is sensitive to diameter variations and is not distributed among branches of a junction. Moreover, the fundamental relation between waves and hydraulic power is unclear. We, therefore, propose an alternative to wave intensity called "wave 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 wave-related components (ΠP±and ΠQ±). Wave 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 waves at junctions; and3) it has the units of power (Watts). We also uncover a simple relationship between wave power and changes in ΠP±and show that wave reflection reduces transmitted power. Absolute values of ΠP±represent wave potential, a recently introduced concept that unifies steady and pulsatile aspects of hemodynamics. We show that wave potential represents the hydraulic energy potential stored in a compliant pressurized vessel, with spatial gradients producing waves 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 "wave power analysis," encompassing wave power, wave potential, and wave separation of hydraulic power provides a potent time-domain approach for analyzing hemodynamics.
NASA Astrophysics Data System (ADS)
Brossier, Romain; Zhou, Wei; Operto, Stéphane; Virieux, Jean
2015-04-01
Full Waveform Inversion (FWI) is an appealing method for quantitative high-resolution subsurface imaging (Virieux et al., 2009). For crustal-scales exploration from surface seismic, FWI generally succeeds in recovering a broadband of wavenumbers in the shallow part of the targeted medium taking advantage of the broad scattering-angle provided by both reflected and diving waves. In contrast, deeper targets are often only illuminated by short-spread reflections, which favor the reconstruction of the short wavelengths at the expense of the longer ones, leading to a possible notch in the intermediate part of the wavenumber spectrum. To update the velocity macromodel from reflection data, image-domain strategies (e.g., Symes & Carazzone, 1991) aim to maximize a semblance criterion in the migrated domain. Alternatively, recent data-domain strategies (e.g., Xu et al., 2012, Ma & Hale, 2013, Brossier et al., 2014), called Reflection FWI (RFWI), inspired by Chavent et al. (1994), rely on a scale separation between the velocity macromodel and prior knowledge of the reflectivity to emphasize the transmission regime in the sensitivity kernel of the inversion. However, all these strategies focus on reflected waves only, discarding the low-wavenumber information carried out by diving waves. With the current development of very long-offset and wide-azimuth acquisitions, a significant part of the recorded energy is provided by diving waves and subcritical reflections, and high-resolution tomographic methods should take advantage of all types of waves. In this presentation, we will first review the issues of classical FWI when applied to reflected waves and how RFWI is able to retrieve the long wavelength of the model. We then propose a unified formulation of FWI (Zhou et al., 2014) to update the low wavenumbers of the velocity model by the joint inversion of diving and reflected arrivals, while the impedance model is updated thanks to reflected wave only. An alternate inversion of
Terrestrial detector for low frequency gravitational waves based on full tensor measurement
NASA Astrophysics Data System (ADS)
Lee, Hyung Mok; Paik, Hojung; Majorana, Ettore; Vol Moody, M.; Griggs, Cornelius E.; Nielsen, Alex; Kim, Chumglee
2015-08-01
Terrestrial gravitational wave (GW) detectors are mostly based on Michelson-type laser interferometers with arm lengths of a few km to reach a strain sensitivity of 10-23 Hz-1/2 in the frequency range of a few 100 to a few 1000 Hz. There should be a large variety of sources generating GWs at lower frequencies below 10 Hz. However, seismic and Newtonian noise has been serious obstacle in realizing terrestrial low-frequency GW detectors. Here we describe a new GW detector concept by adopting new measurement techniques and configurations to overcome the present low-frequency barrier due to seismic and Newtonian noise. The detector is an extension of the superconducting gravity gradiometer (SGG) that has been developed at the University of Maryland to measure all components of the gravity gradient tensor by orthogonally combining three bars with test masses at each end. The oscillating component of the gravity gradient tensor is the GW strain tensor, but the actual signal is likely to be dominated by Newtonian and seismic noise, whose amplitudes are several orders of magnitude larger than the GWs. We propose to mitigate seismic noise by (a) constructing detector in deep underground, (b) applying passive isolation with pendulum suspension, and (c) using the common-mode rejection characteristic of the detector. The Newtonian noise can be suppressed by combining the components of the gradient tensor with signals detected by seismometers and microphones. By constructing a detector of 100-m long bars cooled to 0.1 K, a strain sensitivity of a few times 10-21 Hz-1/2 can be achieved in the frequency range between 0.1 to 10 Hz. Binaries composed of intermediate mass black holes of 1000 to 10,000 M¤ could be detected at distances up to a few Gpc with this detector. Detectable range for the merging white dwarf binaries is up to a few Mpc. Unlike current two-dimensional detectors, our single detector is able to determine the polarization of GWs and the direction to sources on
Choi, Myunghee; Chan, Vincent S.
2014-02-28
This final report describes the work performed under U.S. Department of Energy Cooperative Agreement DE-FC02-08ER54954 for the period April 1, 2011 through March 31, 2013. The goal of this project was to perform iterated finite-orbit Monte Carlo simulations with full-wall fields for modeling tokamak ICRF wave heating experiments. In year 1, the finite-orbit Monte-Carlo code ORBIT-RF and its iteration algorithms with the full-wave code AORSA were improved to enable systematical study of the factors responsible for the discrepancy in the simulated and the measured fast-ion FIDA signals in the DIII-D and NSTX ICRF fast-wave (FW) experiments. In year 2, ORBIT-RF was coupled to the TORIC full-wave code for a comparative study of ORBIT-RF/TORIC and ORBIT-RF/AORSA results in FW experiments.
Wavelet analysis of internal gravity waves
NASA Astrophysics Data System (ADS)
Hawkins, J.; Warn-Varnas, A.; Chin-Bing, S.; King, D.; Smolarkiewicsz, P.
2005-05-01
A series of model studies of internal gravity waves (igw) have been conducted for several regions of interest. Dispersion relations from the results have been computed using wavelet analysis as described by Meyers (1993). The wavelet transform is repeatedly applied over time and the components are evaluated with respect to their amplitude and peak position (Torrence and Compo, 1998). In this sense we have been able to compute dispersion relations from model results and from measured data. Qualitative agreement has been obtained in some cases. The results from wavelet analysis must be carefully interpreted because the igw models are fully nonlinear and wavelet analysis is fundamentally a linear technique. Nevertheless, a great deal of information describing igw propagation can be obtained from the wavelet transform. We address the domains over which wavelet analysis techniques can be applied and discuss the limits of their applicability.
NASA Astrophysics Data System (ADS)
Wang, Yi; Chevrot, Sébastien; Komatitsch, Dimitri; Monteiller, Vadim; Durochat, Clément
2016-04-01
Thanks to the deployment of permanent and temporary broadband arrays, coverage and data quality have dramatically improved in the last decade, especially for regional-scale studies. In addition, owing to the progress of high-performance resources and numerical simulation techniques, waveform inversion approaches nowadays become a viable alternative to classical asymptotic ray based tomographic approaches. Exploiting full waveforms in seismic tomography requires an efficient and precise method to solve the elastic wave equation in 3D inhomogeneous media. Since resolution of waveform inversion is limited by the seismic wavelength as well as the wavefield sampling density, it is crucial to exploit short-period teleseismic waves recorded by dense regional arrays. However, modeling the propagation of short-period body waves in heterogeneous media is still very challenging, even on the largest modern supercomputers. For this reason, we have developed a hybrid method that couples a global wave propagation method in a 1D Earth to a 3D spectral-element method in a regional domain. This hybrid method restricts the costly 3D computations to inside the regional domain, which dramatically decreases the computational cost, allows us to compute teleseismic wavefields down to 1s period, thus accounting for the complexities that affect the propagation of seismic waves in the regional domain. We present the first application of this new waveform inversion approach to broadband data coming from two dense transects deployed during the PYROPE experiment across the Pyrenees mountains. We obtain the first high-resolution lithospheric section of compressional and shear velocities across an orogenic belt. The tomographic model provides clear evidence for the under-thrusting of the thinned Iberian crust beneath the European plate and for the important role of rift-inherited mantle structures during the formation of the Pyrenees.
NASA Astrophysics Data System (ADS)
Velichko, A.; Wilcox, P. D.
2009-03-01
The paper describes a method for processing data from a guided wave transducer array on a pipe. The raw data set from such an array contains the full matrix of time-domain signals from each transmitter-receiver combination. It is shown that for certain configurations of an array the total focusing method can be applied which allows the array to be focused at every point on a pipe surface in both transmission and reception. The effect of array configuration parameters on the sensitivity of the proposed method to the random and coherent noise is discussed. Experimental results are presented using electromagnetic acoustic transducers (EMAT) for exciting and detecting the S0 Lamb wave mode in a 12 inch steel pipe at 200 kHz excitation frequency. The results show that using the imaging algorithm a 2-mm-diameter (0.08 wavelength) half-thickness hole can be detected.
NASA Astrophysics Data System (ADS)
Zhou, Wei; Brossier, Romain; Operto, Stéphane; Virieux, Jean
2015-09-01
Full waveform inversion (FWI) aims to reconstruct high-resolution subsurface models from the full wavefield, which includes diving waves, post-critical reflections and short-spread reflections. Most successful applications of FWI are driven by the information carried by diving waves and post-critical reflections to build the long-to-intermediate wavelengths of the velocity structure. Alternative approaches, referred to as reflection waveform inversion (RWI), have been recently revisited to retrieve these long-to-intermediate wavelengths from short-spread reflections by using some prior knowledge of the reflectivity and a scale separation between the velocity macromodel and the reflectivity. This study presents a unified formalism of FWI, named as Joint FWI, whose aim is to efficiently combine the diving and reflected waves for velocity model building. The two key ingredients of Joint FWI are, on the data side, the explicit separation between the short-spread reflections and the wide-angle arrivals and, on the model side, the scale separation between the velocity macromodel and the short-scale impedance model. The velocity model and the impedance model are updated in an alternate way by Joint FWI and waveform inversion of the reflection data (least-squares migration), respectively. Starting from a crude velocity model, Joint FWI is applied to the streamer seismic data computed in the synthetic Valhall model. While the conventional FWI is stuck into a local minimum due to cycle skipping, Joint FWI succeeds in building a reliable velocity macromodel. Compared with RWI, the use of diving waves in Joint FWI improves the reconstruction of shallow velocities, which translates into an improved imaging at deeper depths. The smooth velocity model built by Joint FWI can be subsequently used as a reliable initial model for conventional FWI to increase the high-wavenumber content of the velocity model.
Mixed augmented variational formulation (MAVF) for lower hybrid full-wave calculations
Peysson, Y.; Roche, J. R.; Kirsch, C.; Mokrani, A.; Labrunie, S.; Bertrand, P.; Chatenet, J.-H.
2009-11-26
In the continuation of the works led in cylindrical geometry, a full toroidal description for an arbitrary poloidal cross-section of the plasma has been developed. For simulation purpose a mixed augmented variational formulation (MAVF), which is particularly well suited for solving Maxwell equations, is considered. The discretization of the MAVF is carried out using Taylor-Hood P2-iso-P1 finite elements. This formulation provide a natural implementation for parallel processing, a particularly important aspect when simulations for plasmas of large size must be considered. Details on the specific application of the MAVF to the LH problem are presented, as well as the structure of the corresponding matrices. A first application to a realistic small tokamak configuration is considered.
GPView: A program for wave function analysis and visualization.
Shi, Tian; Wang, Ping
2016-11-01
In this manuscript, we will introduce a recently developed program GPView, which can be used for wave function analysis and visualization. The wave function analysis module can calculate and generate 3D cubes for various types of molecular orbitals and electron density of electronic excited states, such as natural orbitals, natural transition orbitals, natural difference orbitals, hole-particle density, detachment-attachment density and transition density. The visualization module of GPView can display molecular and electronic (iso-surfaces) structures. It is also able to animate single trajectories of molecular dynamics and non-adiabatic excited state molecular dynamics using the data stored in existing files. There are also other utilities to extract and process the output of quantum chemistry calculations. The GPView provides full graphic user interface (GUI), so it very easy to use. It is available from website http://life-tp.com/gpview.
Bertelli, N. Gerhardt, S.; Hosea, J. C.; LeBlanc, B.; Perkins, R. J.; Phillips, C. K.; Taylor, G.; Valeo, E. J.; Wilson, J. R.; Jaeger, E. F.; Lau, C.; Blazevski, D.; Green, D. L.; Berry, L.; Ryan, P. M.; Bonoli, P. T.; Wright, J. C.; Pinsker, R. I.; Prater, R.; Qin, C. M.; and others
2015-12-10
Several experiments on different machines and in different fast wave (FW) heating regimes, such as hydrogen minority heating and high harmonic fast waves, have found strong interactions between radio-frequency (RF) waves and the scrape-off layer (SOL) region. This paper examines the propagation and the power loss in the SOL by using the full wave code AORSA, in which the edge plasma beyond the last closed flux surface (LCFS) is included in the solution domain and a collisional damping parameter is used as a proxy to represent the real, and most likely nonlinear, damping processes. 3D AORSA results for the National Spherical Torus eXperiment (NSTX), where a full antenna spectrum is reconstructed, are shown, confirming the same behavior found for a single toroidal mode results in Bertelli et al, Nucl. Fusion, 54 083004, 2014, namely, a strong transition to higher SOL power losses (driven by the RF field) when the FW cut-off is moved away from in front of the antenna by increasing the edge density. Additionally, full wave simulations have been extended to “conventional” tokamaks with higher aspect ratios, such as the DIII-D, Alcator C-Mod, and EAST devices. DIII-D results show similar behavior found in NSTX and NSTX-U, consistent with previous DIII-D experimental observations. In contrast, a different behavior has been found for Alcator C-Mod and EAST, which operate in the minority heating regime unlike NSTX/NSTX-U and DIII-D, which operate in the mid/high harmonic regime. A substantial discussion of some of the main aspects, such as (i) the pitch angle of the magnetic field; (ii) minority heating vs. mid/high harmonic regimes is presented showing the different behavior of the RF field in the SOL region for NSTX-U scenarios with different plasma current. Finally, the preliminary results of the impact of the SOL region on the evaluation of the helicon current drive efficiency in DIII-D is presented for the first time and briefly compared with the different regimes
Bertelli, Nicola; Jaeger, E. F.; Lau, Cornwall H; Blazevski, Dan; Green, David L; Berry, Lee Alan; Bonoli, P. T.; Gerhardt, S.P.; Hosea, J. C.; LeBlanc, B.; Perkins, R. J.; Phillips, Cynthia; Pinsker, R. I.; Prater, R.; Qin, C M; Ryan, P. M.; Taylor, G.; Valeo, E. J.; Wilson, Randy; Wright, J.; Zhang, X J
2015-01-01
Several experiments on different machines and in different fast wave (FW) heating regimes, such as hydrogen minority heating and high harmonic fast waves, have found strong interactions between radio-frequency (RF) waves and the scrape-off layer (SOL) region. This paper examines the propagation and the power loss in the SOL by using the full wave code AORSA, in which the edge plasma beyond the last closed flux surface (LCFS) is included in the solution domain and a collisional damping parameter is used as a proxy to represent the real, and most likely nonlinear, damping processes. 3D AORSA results for the National Spherical Torus eXperiment (NSTX), where a full antenna spectrum is reconstructed, are shown, confirming the same behavior found for a single toroidal mode results in Bertelli et al, Nucl. Fusion, 54 083004, 2014, namely, a strong transition to higher SOL power losses (driven by the RF field) when the FW cut-off is moved away from in front of the antenna by increasing the edge density. Additionally, full wave simulations have been extended to "conventional" tokamaks with higher aspect ratios, such as the DIII-D, Alcator C-Mod, and EAST devices. DIII-D results show similar behavior found in NSTX and NSTX-U, consistent with previous DIII-D experimental observations. In contrast, a different behavior has been found for Alcator C-Mod and EAST, which operate in the minority heating regime unlike NSTX/NSTX-U and DIII-D, which operate in the mid/high harmonic regime. A substantial discussion of some of the main aspects, such as (i) the pitch angle of the magnetic field; (ii) minority heating vs. mid/high harmonic regimes is presented showing the different behavior of the RF field in the SOL region for NSTX-U scenarios with different plasma current. Finally, the preliminary results of the impact of the SOL region on the evaluation of the helicon current drive efficiency in DIII-D is presented for the first time and briefly compared with the different regimes
Full-wave solution for an aperture-coupled patch fed by perpendicular coplanar strips
NASA Astrophysics Data System (ADS)
Herscovici, Naftali I.; Pozar, D. M.
1994-04-01
In recent years, the rectangular slot has been proposed as a means of power transfer between layers in multilayer printed antennas. Compared to probes, slots reduce fabrication complexity considerably, and allow more flexibility in the design of multilayer configurations. In the past, the aperture-coupled microstrip patch has been analyzed using the reciprocity theorem for the feeding line and the method of moments for the patch. The same method is used here for the analysis of an aperture-coupled patch fed by perpendicular coplanar strips. Theoretical results from this solution are compared with measurements for the input impedance of this antenna, and design data are given for the characteristic impedance of the coplanar strip feed line.
Full waveform inversion of seismic waves reflected in a stratified porous medium
NASA Astrophysics Data System (ADS)
De Barros, Louis; Dietrich, Michel; Valette, Bernard
2010-09-01
In reservoir geophysics applications, seismic imaging techniques are expected to provide as much information as possible on fluid-filled reservoir rocks. Since seismograms are, to some degree, sensitive to the mechanical parameters and fluid properties of porous media, inversion methods can be devised to directly estimate these quantities from the waveforms obtained in seismic reflection experiments. An inversion algorithm that uses a generalized least-squares, quasi-Newton approach is described to determine the porosity, permeability, interstitial fluid properties and mechanical parameters of porous media. The proposed algorithm proceeds by iteratively minimizing a misfit function between observed data and synthetic wavefields computed with the Biot theory. Simple models consisting of plane-layered, fluid-saturated and poro-elastic media are considered to demonstrate the concept and evaluate the performance of such a full waveform inversion scheme. Numerical experiments show that, when applied to synthetic data, the inversion procedure can accurately reconstruct the vertical distribution of a single model parameter, if all other parameters are perfectly known. However, the coupling between some of the model parameters does not permit the reconstruction of several model parameters at the same time. To get around this problem, we consider composite parameters defined from the original model properties and from a priori information, such as the fluid saturation rate or the lithology, to reduce the number of unknowns. Another possibility is to apply this inversion algorithm to time-lapse surveys carried out for fluid substitution problems, such as CO2 injection, since in this case only a few parameters may vary as a function of time. We define a two-step differential inversion approach which allows us to reconstruct the fluid saturation rate in reservoir layers, even though the medium properties are poorly known.
Choi, M.; Chan, V. S.; Lao, L. L.; Pinsker, R. I.; Green, D.; Berry, L. A.; Jaeger, F.; Park, J. M.; Heidbrink, W. W.; Liu, D.; Podesta, M.; Harvey, R.; Smithe, D. N.; Bonoli, P.
2010-05-15
The five-dimensional finite-orbit Monte Carlo code ORBIT-RF[M. Choi et al., Phys. Plasmas 12, 1 (2005)] is successfully coupled with the two-dimensional full-wave code all-orders spectral algorithm (AORSA) [E. F. Jaeger et al., Phys. Plasmas 13, 056101 (2006)] in a self-consistent way to achieve improved predictive modeling for ion cyclotron resonance frequency (ICRF) wave heating experiments in present fusion devices and future ITER [R. Aymar et al., Nucl. Fusion 41, 1301 (2001)]. The ORBIT-RF/AORSA simulations reproduce fast-ion spectra and spatial profiles qualitatively consistent with fast ion D-alpha [W. W. Heidbrink et al., Plasma Phys. Controlled Fusion 49, 1457 (2007)] spectroscopic data in both DIII-D [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] and National Spherical Torus Experiment [M. Ono et al., Nucl. Fusion 41, 1435 (2001)] high harmonic ICRF heating experiments. This work verifies that both finite-orbit width effect of fast-ion due to its drift motion along the torus and iterations between fast-ion distribution and wave fields are important in modeling ICRF heating experiments.
Choi, M.; Green, David L; Heidbrink, W. W.; Harvey, R. W.; Liu, D.; Chan, V. S.; Berry, Lee A; Jaeger, Erwin Frederick; Lao, L.L.; Pinsker, R. I.; Podesta, M.; Smithe, D. N.; Park, J. M.; Bonoli, P.
2010-01-01
The five-dimensional finite-orbit Monte Carlo code ORBIT-RF [M. Choi , Phys. Plasmas 12, 1 (2005)] is successfully coupled with the two-dimensional full-wave code all-orders spectral algorithm (AORSA) [E. F. Jaeger , Phys. Plasmas 13, 056101 (2006)] in a self-consistent way to achieve improved predictive modeling for ion cyclotron resonance frequency (ICRF) wave heating experiments in present fusion devices and future ITER [R. Aymar , Nucl. Fusion 41, 1301 (2001)]. The ORBIT-RF/AORSA simulations reproduce fast-ion spectra and spatial profiles qualitatively consistent with fast ion D-alpha [W. W. Heidbrink , Plasma Phys. Controlled Fusion 49, 1457 (2007)] spectroscopic data in both DIII-D [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] and National Spherical Torus Experiment [M. Ono , Nucl. Fusion 41, 1435 (2001)] high harmonic ICRF heating experiments. This work verifies that both finite-orbit width effect of fast-ion due to its drift motion along the torus and iterations between fast-ion distribution and wave fields are important in modeling ICRF heating experiments. (C) 2010 American Institute of Physics. [doi:10.1063/1.3314336
Vdovin V.L.
2005-08-15
In this report we describe theory and 3D full wave code description for the wave excitation, propagation and absorption in 3-dimensional (3D) stellarator equilibrium high beta plasma in ion cyclotron frequency range (ICRF). This theory forms a basis for a 3D code creation, urgently needed for the ICRF heating scenarios development for the operated LHD, constructed W7-X, NCSX and projected CSX3 stellarators, as well for re evaluation of ICRF scenarios in operated tokamaks and in the ITER . The theory solves the 3D Maxwell-Vlasov antenna-plasma-conducting shell boundary value problem in the non-orthogonal flux coordinates ({Psi}, {theta}, {var_phi}), {Psi} being magnetic flux function, {theta} and {var_phi} being the poloidal and toroidal angles, respectively. All basic physics, like wave refraction, reflection and diffraction are self consistently included, along with the fundamental ion and ion minority cyclotron resonances, two ion hybrid resonance, electron Landau and TTMP absorption. Antenna reactive impedance and loading resistance are also calculated and urgently needed for an antenna -generator matching. This is accomplished in a real confining magnetic field being varying in a plasma major radius direction, in toroidal and poloidal directions, through making use of the hot dense plasma wave induced currents with account to the finite Larmor radius effects. We expand the solution in Fourier series over the toroidal ({var_phi}) and poloidal ({theta}) angles and solve resulting ordinary differential equations in a radial like {Psi}-coordinate by finite difference method. The constructed discretization scheme is divergent-free one, thus retaining the basic properties of original equations. The Fourier expansion over the angle coordinates has given to us the possibility to correctly construct the ''parallel'' wave number k{sub //}, and thereby to correctly describe the ICRF waves absorption by a hot plasma. The toroidal harmonics are tightly coupled with each
NASA Astrophysics Data System (ADS)
Fan, D.; Mao, Z.; Lin, J.; Yang, J.
2013-12-01
Brillouin light scattering (BLS) is the inelastic scattering of monochromatic laser light by phonons in the GHz frequency range [1]. BLS spectroscopy can be used to measure sound velocities traveling along certain directions of a single crystal through the frequency shifts of the scattered light from the acoustic phonons [1]. Over the past few decades, BLS spectroscopy has been widely used to measure the velocities of acoustic waves for a wide range of Earth's materials, in which the full elastic constants were derived from the measured compressional (VP) and shear wave (VS) velocities. However, the VP velocities of minerals normally overlap with the shear-wave velocities of diamonds in Brillouin measurements approximately above 25 GPa [2-5] such that only VS of minerals can be measured experimentally. Theoretical models have showed that the shear-wave velocities of minerals also carry necessary information to invert the full elastic tensors [2], although previous studies at high pressures have focused on measuring velocities within the principle planes of the crystals. This leads to a strong trade-off among individual Cij, preventing the derivation of the full elastic tensors from the VS velocities alone [3-5]. In this study, we have come up with an elastic model to overcome this problem by finding a suitable crystallographic plane that has optimized VS-VP interactions in the elastic tensors. Using MgO, spinel and zoisite as test samples, we have used measured VP/VS or VS velocities of these crystals using BLS spectroscopy to derive their full elastic tensors. This new approach sheds lights on future high-pressure elasticity studies relevant to materials the Earth's deep interior. 1. Sinogeikin, S.V., Bass, J.D., Phys. Earth Planet. Inter., 120, 43 (2000). 2. Every, A. G., Phys. Rev. B., 22, 1746, (1980) 3. Marquardt, H., Speziale, S., Reichmann, H.J., Frost, D.J., and Schilling, F.R., Earth Planet. Sci. Lett., 287, 345 (2009). 4. Marquardt, H., Speziale, S
2.5D Full Waveform Inversion of Teleseismic Body and Surface Waves in the Tien Shan
NASA Astrophysics Data System (ADS)
Baker, B. I.; Roecker, S. W.
2013-12-01
The Tien Shan is the best contemporary example of intracontinental shortening resulting from continental collision, a process believed to have been significant in the evolution of a number of ancient orogens. Previous tomographic studies of the Tien Shan implicate structures in the crust and upper mantle as key to understanding the dynamics of the region. In this study we apply recently developed full waveform inversion (FWI) techniques to passive data collected by the linear dense MANAS array between 2005 to 2007 in order to obtain higher resolution images of lateral heterogeneity beneath the Tien Shan than have previously been available. Our technique is an extension of that proposed by Roecker et al (2010); specifically the forward problem can now account for topographic features with a new 2.5D p-adaptive finite element solver. We incorporate a method developed by Bielak et. al. (2003) to input an appropriate force distribution to accommodate sources external to our model. The p-adaptivity allows us to suit element size to expected resolution as a function of depth and reduce the number of variables in inversion. Consequently, we can now explicitly calculate Frechet derivatives and generate the corresponding Gauss-Newton form with a model covariance regularization matrix all for modest additional computational expense. In order to take advantage of the complimentary sensitivities of different kinds of observations, we simultaneously invert fundamental mode Rayleigh waves and teleseismic P-wave coda. Our strategy is a multiscale approach by which we fit the longer period surface waves first followed by inclusion of body wave data.
AE Source Orientation by Plate Wave Analysis
NASA Technical Reports Server (NTRS)
Gorman, Michael R.; Prosser, William H.
1991-01-01
Lead breaks (Hsu-Neilsen source) were used to generate simulated acoustic emission signals in an aluminum plate at angles of 0, 30, 60, and 90 degrees with respect to the plane of the plate. This was accomplished by breaking the lead on slots cut into the plate at the respective angles. The out-of-plane and in-plane displacement components of the resulting signals were detected by broad band transducers and digitized. Analysis of the waveforms showed them to consist of the extensional and flexural plate modes. The amplitude of both components of the two modes was dependent on the source orientation angle. This suggests that plate wave analysis may be used to determine the source orientation of acoustic emission sources.
Full-Envelope Launch Abort System Performance Analysis Methodology
NASA Technical Reports Server (NTRS)
Aubuchon, Vanessa V.
2014-01-01
The implementation of a new dispersion methodology is described, which dis-perses abort initiation altitude or time along with all other Launch Abort System (LAS) parameters during Monte Carlo simulations. In contrast, the standard methodology assumes that an abort initiation condition is held constant (e.g., aborts initiated at altitude for Mach 1, altitude for maximum dynamic pressure, etc.) while dispersing other LAS parameters. The standard method results in large gaps in performance information due to the discrete nature of initiation conditions, while the full-envelope dispersion method provides a significantly more comprehensive assessment of LAS abort performance for the full launch vehicle ascent flight envelope and identifies performance "pinch-points" that may occur at flight conditions outside of those contained in the discrete set. The new method has significantly increased the fidelity of LAS abort simulations and confidence in the results.
Quantitative full time course analysis of nonlinear enzyme cycling kinetics.
Cao, Wenxiang; De La Cruz, Enrique M
2013-01-01
Enzyme inhibition due to the reversible binding of reaction products is common and underlies the origins of negative feedback inhibition in many metabolic and signaling pathways. Product inhibition generates non-linearity in steady-state time courses of enzyme activity, which limits the utility of well-established enzymology approaches developed under the assumption of irreversible product release. For more than a century, numerous attempts to find a mathematical solution for analysis of kinetic time courses with product inhibition have been put forth. However, no practical general method capable of extracting common enzymatic parameters from such non-linear time courses has been successfully developed. Here we present a simple and practical method of analysis capable of efficiently extracting steady-state enzyme kinetic parameters and product binding constants from non-linear kinetic time courses with product inhibition and/or substrate depletion. The method is general and applicable to all enzyme systems, independent of reaction schemes and pathways.
Preliminary analysis of knee stress in Full Extension Landing
Makinejad, Majid Davoodi; Abu Osman, Noor Azuan; Wan Abas, Wan Abu Bakar; Bayat, Mehdi
2013-01-01
OBJECTIVE: This study provides an experimental and finite element analysis of knee-joint structure during extended-knee landing based on the extracted impact force, and it numerically identifies the contact pressure, stress distribution and possibility of bone-to-bone contact when a subject lands from a safe height. METHODS: The impact time and loads were measured via inverse dynamic analysis of free landing without knee flexion from three different heights (25, 50 and 75 cm), using five subjects with an average body mass index of 18.8. Three-dimensional data were developed from computed tomography scans and were reprocessed with modeling software before being imported and analyzed by finite element analysis software. The whole leg was considered to be a fixed middle-hinged structure, while impact loads were applied to the femur in an upward direction. RESULTS: Straight landing exerted an enormous amount of pressure on the knee joint as a result of the body's inability to utilize the lower extremity muscles, thereby maximizing the threat of injury when the load exceeds the height-safety threshold. CONCLUSIONS: The researchers conclude that extended-knee landing results in serious deformation of the meniscus and cartilage and increases the risk of bone-to-bone contact and serious knee injury when the load exceeds the threshold safety height. This risk is considerably greater than the risk of injury associated with walking downhill or flexion landing activities. PMID:24141832
Full Core Reactor Analysis: Running Denovo on Jaguar
Jarrell, Joshua J; Godfrey, Andrew T; Evans, Thomas M; Davidson, Gregory G
2012-01-01
Fully-consistent, full-core, 3D, deterministic simulations using the orthogonal mesh code Denovo were run on the massively parallel computing architecture Jaguar XT5. Using energy and spatial parallelization schemes, Denovo was able to efficiently scale to over 160k processors. Cell-homogenized cross-sections were used with Step-Characteristics, Linear-Discontinuous Finite Element, and Tri-Linear-Discontinuous Finite Element spatial methods. It was determined that using the finite element methods gave considerably more accurate eigenvalue solutions for large aspect ratios meshes than those using Step-Characteristics.
Full Core Reactor Analysis: Running Denovo on Jaguar
Jarrell, Joshua J; Godfrey, Andrew T; Evans, Thomas M; Davidson, Gregory G
2013-01-01
Fully-consistent, full-core, 3D, deterministic neutron transport simulations using the orthogonal mesh code Denovo were run on the massively parallel computing architecture Jaguar XT5. Using energy and spatial parallelization schemes, Denovo was able to efficiently scale to more than 160k processors. Cell-homogenized cross sections were used with step-characteristics, linear-discontinuous finite element, and trilinear-discontinuous finite element spatial methods. It was determined that using the finite element methods gave considerably more accurate eigenvalue solutions for large-aspect ratio meshes than using step-characteristics.
Full core reactor analysis: Running Denovo on Jaguar
Jarrell, J. J.; Godfrey, A. T.; Evans, T. M.; Davidson, G. G.
2012-07-01
Fully-consistent, full-core, 3D, deterministic neutron transport simulations using the orthogonal mesh code Denovo were run on the massively parallel computing architecture Jaguar XT5. Using energy and spatial parallelization schemes, Denovo was able to efficiently scale to more than 160 k processors. Cell-homogenized cross sections were used with step-characteristics, linear-discontinuous finite element, and trilinear-discontinuous finite element spatial methods. It was determined that using the finite element methods gave considerably more accurate eigenvalue solutions for large-aspect ratio meshes than using step-characteristics. (authors)
Wave Journal Bearing. Part 1: Analysis
NASA Technical Reports Server (NTRS)
Dimofte, Florin
1995-01-01
A wave journal bearing concept features a waved inner bearing diameter of the non-rotating bearing side and it is an alternative to the plain journal bearing. The wave journal bearing has a significantly increased load capacity in comparison to the plain journal bearing operating at the same eccentricity. It also offers greater stability than the plain circular bearing under all operating conditions. The wave bearing's design is relatively simple and allows the shaft to rotate in either direction. Three wave bearings are sensitive to the direction of an applied stationary side load. Increasing the number of waves reduces the wave bearing's sensitivity to the direction of the applied load relative to the wave. However, the range in which the bearing performance can be varied decreases as the number of waves increases. Therefore, both the number and the amplitude of the waves must be properly selected to optimize the wave bearing design for a specific application. It is concluded that the stiffness of an air journal bearing, due to hydrodynamic effect, could be doubled and made to run stably by using a six or eight wave geometry with a wave amplitude approximately half of the bearing radial clearance.
Mathematical Methods in Wave Propagation: Part 2--Non-Linear Wave Front Analysis
ERIC Educational Resources Information Center
Jeffrey, Alan
1971-01-01
The paper presents applications and methods of analysis for non-linear hyperbolic partial differential equations. The paper is concluded by an account of wave front analysis as applied to the piston problem of gas dynamics. (JG)
ICE/ISEE plasma wave data analysis
NASA Technical Reports Server (NTRS)
Greenstadt, E. W.; Moses, S. L.
1993-01-01
This report is one of the final processing of ICE plasma wave (pw) data and analysis of late ISEE 3, ICE cometary, and ICE cruise trajectory data, where coronal mass ejections (CME's) were the first locus of attention. Interest in CME's inspired an effort to represent our pw data in a condensed spectrogram format that facilitated rapid digestion of interplanetary phenomena on long (greater than 1 day) time scales. The format serendipitously allowed us to also examine earth-orbiting data from a new perspective, invigorating older areas of investigation in Earth's immediate environment. We, therefore, continued to examine with great interest the last year of ISEE 3's precomet phase, when it spent considerable time far downwind from Earth, recording for days on end conditions upstream, downstream, and across the very weak, distant flank bow shock. Among other motivations has been the apparent similarity of some shock and post shock structures to the signatures of the bow wave surrounding comet Giacobini-Zinner, whose ICE-phase data we revisited.
Centaur Standard Shroud (CSS) full jettison test dynamic analysis
NASA Technical Reports Server (NTRS)
Kasper, H. J.; Donovan, R. M.
1974-01-01
During the space power facility jettison tests, the non-domed half of the Centaur standard shroud was allowed to completely separate from its hinge connection and was caught in a horizontal catch net. A rigid body dynamic analysis that was performed to predict the half shroud prior to and after net contact is presented. Analytical predictions of the longitudinal and circumferential bending moments imposed on the half shroud by the catch net and the net pressure on the half shroud corrugated skin are also presented.
Full core analysis of IRIS reactor by using MCNPX.
Amin, E A; Bashter, I I; Hassan, Nabil M; Mustafa, S S
2016-07-01
This paper describes neutronic analysis for fresh fuelled IRIS (International Reactor Innovative and Secure) reactor by MCNPX code. The analysis included criticality calculations, radial power and axial power distribution, nuclear peaking factor and axial offset percent at the beginning of fuel cycle. The effective multiplication factor obtained by MCNPX code is compared with previous calculations by HELIOS/NESTLE, CASMO/SIMULATE, modified CORD-2 nodal calculations and SAS2H/KENO-V code systems. It is found that k-eff value obtained by MCNPX is closer to CORD-2 value. The radial and axial powers are compared with other published results carried out using SAS2H/KENO-V code. Moreover, the WIMS-D5 code is used for studying the effect of enriched boron in form of ZrB2 on the effective multiplication factor (K-eff) of the fuel pin. In this part of calculation, K-eff is calculated at different concentrations of Boron-10 in mg/cm at different stages of burnup of unit cell. The results of this part are compared with published results performed by HELIOS code.
Full Text Clustering and Relationship Network Analysis of Biomedical Publications
Guan, Renchu; Yang, Chen; Marchese, Maurizio; Liang, Yanchun; Shi, Xiaohu
2014-01-01
Rapid developments in the biomedical sciences have increased the demand for automatic clustering of biomedical publications. In contrast to current approaches to text clustering, which focus exclusively on the contents of abstracts, a novel method is proposed for clustering and analysis of complete biomedical article texts. To reduce dimensionality, Cosine Coefficient is used on a sub-space of only two vectors, instead of computing the Euclidean distance within the space of all vectors. Then a strategy and algorithm is introduced for Semi-supervised Affinity Propagation (SSAP) to improve analysis efficiency, using biomedical journal names as an evaluation background. Experimental results show that by avoiding high-dimensional sparse matrix computations, SSAP outperforms conventional k-means methods and improves upon the standard Affinity Propagation algorithm. In constructing a directed relationship network and distribution matrix for the clustering results, it can be noted that overlaps in scope and interests among BioMed publications can be easily identified, providing a valuable analytical tool for editors, authors and readers. PMID:25250864
BOOK REVIEW Analysis of Gravitational-Wave Data Analysis of Gravitational-Wave Data
NASA Astrophysics Data System (ADS)
Fairhurst, Stephen
2010-12-01
The field of gravitational-wave data analysis has expanded greatly over the past decade and significant developments have been made in methods of analyzing the data taken by resonant bar and interferometric detectors, as well as analysis of mock LISA data. This book introduces much of the required theoretical background in gravitational physics, statistics and time series analysis before moving on to a discussion of gravitational-wave data analysis techniques themselves. The book opens with an overview of the theory of gravitational radiation, providing a comprehensive discussion of various introductory topics: linearized gravity, transverse traceless gauge, the effects of gravitational waves (via geodesic deviation), energy and momentum carried by the waves, and generation of gravitational waves. The second chapter provides an introduction to the various sources of gravitational waves, followed by more detailed expositions on some of the primary sources. For example, the description of compact binary coalescence is thorough and includes a brief exposition of the post-Newtonian formalism and the effective one body method. There also follows extended derivations of gravitational waves from distorted neutron stars, supernovae and a stochastic background. Chapter three provides an introduction to the statistical theory of signal detection, including a discussion of parameter estimation via the Fisher matrix formalism. This is presented from a very mathematical, postulate based, standpoint and I expect that even established gravitational-wave data analysts will find the derivations here more formal than they are used to. The discussion of likelihood ratio tests and the importance of prior probabilities are presented particularly clearly. The fourth chapter covers time series analysis, with power spectrum estimation, extraction of periodic signals and goodness of fit tests. Chapter five switches topics and gives the details of the response of gravitational-wave
Analysis of Radarsat-2 Full Polarimetric Data for Forest Mapping
NASA Astrophysics Data System (ADS)
Maghsoudi, Yasser
Forests are a major natural resource of the Earth and control a wide range of environmental processes. Forests comprise a major part of the planet's plant biodiversity and have an important role in the global hydrological and biochemical cycles. Among the numerous potential applications of remote sensing in forestry, forest mapping plays a vital role for characterization of the forest in terms of species. Particularly, in Canada where forests occupy 45% of the territory, representing more than 400 million hectares of the total Canadian continental area. In this thesis, the potential of polarimetric SAR (PolSAR) Radarsat-2 data for forest mapping is investigated. This thesis has two principle objectives. First is to propose algorithms for analyzing the PolSAR image data for forest mapping. There are a wide range of SAR parameters that can be derived from PolSAR data. In order to make full use of the discriminative power offered by all these parameters, two categories of methods are proposed. The methods are based on the concept of feature selection and classifier ensemble. First, a nonparametric definition of the evaluation function is proposed and hence the methods NFS and CBFS. Second, a fast wrapper algorithm is proposed for the evaluation function in feature selection and hence the methods FWFS and FWCBFS. Finally, to incorporate the neighboring pixels information in classification an extension of the FWCBFS method i.e. CCBFS is proposed. The second objective of this thesis is to provide a comparison between leaf-on (summer) and leaf-off (fall) season images for forest mapping. Two Radarsat-2 images acquired in fine quad-polarized mode were chosen for this study. The images were collected in leaf-on and leaf-off seasons. We also test the hypothesis whether combining the SAR parameters obtained from both images can provide better results than either individual datasets. The rationale for this combination is that every dataset has some parameters which may be
NASA Astrophysics Data System (ADS)
Emry, E.; Shen, Y.; Nyblade, A.; Bao, X.; Flinders, A. F.
2015-12-01
The relationship between lithospheric structure, mantle flow, and continental rifting along the East African Rift is the subject of ongoing discussion. The upper mantle beneath the Main Ethiopian Rift and the East African Rift farther south has been seismically imaged following the deployment of several temporary regional arrays. However, due to uneven distribution of seismic arrays, key questions regarding a connection between these upper mantle anomalies at the Turkana Depression and the effect that the thick Congo Craton has on diverting upwelling material towards the East African Rift are poorly resolved. We use overlapping records from several temporary and permanent broadband seismic arrays (1980-2014) located throughout the African continent and surrounding regions in order to image the upper mantle beneath the East African Rift and the Congo Craton where regional seismic arrays have not been deployed. We do this by seismic ambient noise tomography using the recently developed frequency-time normalization (FTN) method to extract empirical Green's functions (EGFs) at periods of 7-250 seconds. We cross correlate the normalized continuous records and stack them to obtain EGFs for each temporally coincident station-station pair. We simulate wave propagation through a spherical Earth using a finite-difference method, measure phase delay times between synthetics and EGFs, and invert them for velocity perturbations with 3D Rayleigh wave sensitivity kernels. We will present results from full-wave ambient noise inversions that illuminate upper mantle structure throughout the continent, with particular focus on the Congo Craton and northern sections of the East African Rift System.
Single-molecule analysis of the full transcription cycle
NASA Astrophysics Data System (ADS)
Strick, Terence
2005-03-01
By monitoring the extension of a mechanically stretched, supercoiled DNA molecule containing a single bacterial promoter, we have been able to directly observe in real time the change in DNA extension associated with topological unwinding of ˜1 helical turn of promoter DNA by RNAP during transcription initiation. We find that this stage of transcription initiation is extremely sensitive to the torque acting on the supercoiled DNA. Upon addition of limited sets of nucleotides, changes in the polymerase/promoter interaction which are related to the process of abortive initiation can be studied in detail. Upon addition of the full set of nucleotides, the subsequent stages of transcription -- promoter escape, productive elongation and transcription termination -- can also be observed in real-time. The changes in DNA topology which occur at each of these stages have been determined, and these results provide for the first global view of the entire transcription cycle at the resolution of single molecules. Co-authors: Richard H. Ebright, Chen-Yu Liu and Andrey Revyakin, HHMI & Waksman Institute, Rutgers University.
Full quantum mechanical analysis of atomic three-grating Mach–Zehnder interferometry
Sanz, A.S.; Davidović, M.; Božić, M.
2015-02-15
Atomic three-grating Mach–Zehnder interferometry constitutes an important tool to probe fundamental aspects of the quantum theory. There is, however, a remarkable gap in the literature between the oversimplified models and robust numerical simulations considered to describe the corresponding experiments. Consequently, the former usually lead to paradoxical scenarios, such as the wave–particle dual behavior of atoms, while the latter make difficult the data analysis in simple terms. Here these issues are tackled by means of a simple grating working model consisting of evenly-spaced Gaussian slits. As is shown, this model suffices to explore and explain such experiments both analytically and numerically, giving a good account of the full atomic journey inside the interferometer, and hence contributing to make less mystic the physics involved. More specifically, it provides a clear and unambiguous picture of the wavefront splitting that takes place inside the interferometer, illustrating how the momentum along each emerging diffraction order is well defined even though the wave function itself still displays a rather complex shape. To this end, the local transverse momentum is also introduced in this context as a reliable analytical tool. The splitting, apart from being a key issue to understand atomic Mach–Zehnder interferometry, also demonstrates at a fundamental level how wave and particle aspects are always present in the experiment, without incurring in any contradiction or interpretive paradox. On the other hand, at a practical level, the generality and versatility of the model and methodology presented, makes them suitable to attack analogous problems in a simple manner after a convenient tuning. - Highlights: • A simple model is proposed to analyze experiments based on atomic Mach–Zehnder interferometry. • The model can be easily handled both analytically and computationally. • A theoretical analysis based on the combination of the position and
NASA Astrophysics Data System (ADS)
Monaco, E.; Boffa, N. D.; Memmolo, V.; Ricci, F.; Maio, L.
2016-04-01
A full-scale lower wing panel made of composite material has been designed, manufactured and sensorised within the European Funded research project named SARISTU. The authors contributed to the whole development of the system, from design to implementation as well as to the impacts campaign phase where Barely Visible and Visible Damages (BVID and VID) are to be artificially induced on the panel by a pneumatic impact machine. This work summarise part of the experimental results related to damages production, their assessment by C-SCAN as reference NDT method as well as damage detection of delimitations by a guided waves based SHM. The SHM system is made by customized piezoelectric patches secondary bonded on the wing plate acting both as guided waves sources and receivers. The paper will deal mostly with the experimental impact campaign and the signal analyses carried out to extract the metrics more sensitive to damages induced. Image reconstruction of the damages dimensions and shapes will be also described based mostly on the combination of metrics maps over the plate partial surfaces. Finally a comparison of damages maps obtained by the SHM approach and those obtained by "classic" C-SCAN will be presented analyzing briefly pros and cons of the two different approached as a combination to the most effective structural maintenance scenario of a commercial aircraft.
Full vector spherical harmonic analysis of the Holocene geomagnetic field
NASA Astrophysics Data System (ADS)
Richardson, Marcia
High-quality time-series paleomagnetic measurements have been used to derive spherical harmonic models of Earth's magnetic field for the past 2,000 years. A newly-developed data compilation, PSVMOD2.0 consists of time-series directional and intensity records that significantly improve the data quality and global distribution used to develop previous spherical harmonic models. PSVMOD2.0 consists of 185 paleomagnetic time series records from 85 global sites, including 30 full-vector records (inclination, declination and intensity). It includes data from additional sites in the Southern Hemisphere and Arctic and includes globally distributed sediment relative paleointensity records, significantly improving global coverage over previous models. PSVMOD2.0 records have been assessed in a series of 7 regional intercomparison studies, four in the Northern Hemisphere and 3 in the southern hemisphere. Comparisons on a regional basis have improved the quality and chronology of the data and allowed investigation of spatial coherence and the scale length associated with paleomagnetic secular variation (PSV) features. We have developed a modeling methodology based on nonlinear inversion of the PSVMOD2.0 directional and intensity records. Models of the geomagnetic field in 100-year snapshots have been derived for the past 2,000 with the ultimate goal of developing models spanning the past 8,000 years. We validate the models and the methodology by comparing with the GUFM1 historical models during the 400-year period of overlap. We find that the spatial distribution of sites and quality of data are sufficient to derive models that agree with GUFM1 in the large-scale characteristics of the field. We use the the models derived in this study to downward continue the field to the core-mantle boundary and examine characteristics of the large-scale structure of the magnetic field at the source region. The derived models are temporally consistent from one epoch to the next and exhibit
Statistical analysis of plasmaspheric EMIC waves
NASA Astrophysics Data System (ADS)
Kato, Y.; Miyoshi, Y.; Sakaguchi, K.; Kasahara, Y.; Keika, K.; Shoji, M.; Kitamura, N.; Hasegawa, S.; Kumamoto, A.; Shiokawa, K.
2014-12-01
Electromagnetic ion cyclotron (EMIC) waves in the inner magnetosphere are important since EMIC waves cause the pitch angle scattering of ring current ions as well as relativistic electrons of the radiation belts. Although the spatial distributions of EMIC waves have been investigated by several spacecraft such as CRRES, THEMIS and AMPTE/CCE, there have been little studies on plasmaspheric EMIC waves. We investigate statistically EMIC wave data using the Akebono/VLF measurements. The plasmaspheric EMIC waves tend to be distributed at lower L-shell region (L~2) than the slot region. There are no significant MLT dependences, which are different from the EMIC waves outside the plasmapause. The plasmaspheric EMIC wave frequencies depend on the equatorial cyclotron frequency, suggesting that the plasmaspheric EMIC waves are not propagated from high L-shell but generated near the equivalent L-shell magnetic equator. This result is consistent with the result of the dependence of resonance energy. Using the in-situ thermal plasma density measured by the Akebono satellite, we estimate the resonance energy of energetic ions, and the resonance energies of the plasmaspheric EMIC waves are few tens keV to ~ 1 MeV. The results indicate that the ring current and radiation belt ions may contribute the generation of the plasmaspheric EMIC waves.
Geotail MCA plasma wave data analysis
NASA Technical Reports Server (NTRS)
Anderson, Roger R.
1994-01-01
NASA Grant NAG 5-2346 supports the data analysis effort at The University of Iowa for the GEOTAIL Multi-Channel Analyzer (MCA) which is a part of the GEOTAIL Plasma Wave Instrument (PWI). At the beginning of this reporting period we had just begun to receive our GEOTAIL Sirius data on CD-ROMs. Much programming effort went into adapting and refining the data analysis programs to include the CD-ROM inputs. Programs were also developed to display the high-frequency-resolution PWI Sweep Frequency Analyzer (SFA) data and to include in all the various plot products the electron cyclotron frequency derived from the magnitude of the magnetic field extracted from the GEOTAIL Magnetic Field (MGF) data included in the GEOTAIL Sirius data. We also developed programs to use the MGF data residing in the Institute of Space and Astronautical Science (ISAS) GEOTAIL Scientific Data Base (SDB). Our programmers also developed programs and provided technical support for the GEOTAIL data analysis efforts of Co-lnvestigator William W. L. Taylor at Nichols Research Corporation (NRC). At the end of this report we have included brief summaries of the NRC effort and the progress being made.
IWA : an analysis program for isentropic wave measurements.
Ao, Tommy
2009-02-01
IWA (Isentropic Wave Analysis) is a program for analyzing velocity profiles of isentropic compression experiments. IWA applies incremental impedance matching correction to measured velocity profiles to obtain in-situ particle velocity profiles for Lagrangian wave analysis. From the in-situ velocity profiles, material properties such as wave velocities, stress, strain, strain rate, and strength are calculated. The program can be run in any current version of MATLAB (2008a or later) or as a Windows XP executable.
Silva, F. da
2008-10-15
The EU will supply the plasma position reflectometer for ITER. The system will have channels located at different poloidal positions, some of them obliquely viewing a plasma which has a poloidal density divergence and curvature, both adverse conditions for profile measurements. To understand the impact of such topology in the reconstruction of density profiles a full-wave two-dimensional finite-difference time domain O-mode code with the capability for frequency sweep was used. Simulations show that the reconstructed density profiles still meet the ITER radial accuracy specifications for plasma position (1 cm), except for the highest densities. Other adverse effects such as multireflections induced by the blanket, density fluctuations, and MHD activity were considered and a first understanding on their impact obtained.
NASA Astrophysics Data System (ADS)
Ma, Jianxin; Zhang, Ruijiao; Li, Yanjie; Zhang, Qi; Yu, Jianguo
2015-02-01
A novel full-duplex link with an optical mm-wave local oscillator broadcasting for broadband millimeter (mm)-wave wireless access in W-band is proposed based on the WDM-PON-RoF. In our scheme, a universal optical mm-wave local oscillator in W-band is distributed over the whole network to up-convert the downlink IF optical signal, which not only improves the spectrum efficiency by reducing the bandwidth requirement of each downlink, but also decreases the degradation caused by the fiber chromatic dispersion. Moreover, since the incoherently down-converted uplink signal is modulated on the reused blank optical carrier extracted from the downlink signal, the base stations (BSs) need no optical source, and so its structure is simplified. The numerical simulation results agree well with the theoretical analysis and show that the proposed full-duplex link for the W-band wireless access based on WDM-PON-RoF maintains good performance with cost effective implement.
Dynamic analysis of sea wave data measured by LED lidar
NASA Astrophysics Data System (ADS)
Mori, Yasukuni; Shimada, Shohei; Shiina, Tatsuo; Baji, Hiroyuki; Takemoto, Sae
2016-10-01
Form of sea wave is greatly affected by not just flow and depth of sea water, but also wind blowing on the sea surface. Therefore, measurement and analysis of sea wave motion is of assistance for control and operational safety of boats and ships. Generally, oceanic information is gauged by acoustic and electric wave. But these methods have not provided enough spatial and temporal resolution, and are completely out of touch with the on-site needs. Thus, the LED liar for sea wave measurement has been developed. The dynamic analysis of sea wave image measured by the LED lidar was conducted and the relationship with wind speed was evaluated. In this report, we first present the specifications and measurement methodologies of the LED lidar. Then we describe the actual measurements of sea wave with shallow angle by using this lidar and the results of their analysis.
NASA Technical Reports Server (NTRS)
Koch, Steven E.; Golus, Robert E.
1988-01-01
This paper presents a statistical analysis of the characteristics of the wavelike activity that occurred over the north-central United States on July 11-12, 1981, using data from the Cooperative Convective Precipitation Experiment in Montana. In particular, two distinct wave episodes of about 8-h duration within a longer (33 h) period of wave activity were studied in detail. It is demonstrated that the observed phenomena display features consistent with those of mesoscale gravity waves. The principles of statistical methods used to detect and track mesoscale gravity waves are discussed together with their limitations.
NASA Astrophysics Data System (ADS)
Qiu, Lei; Yuan, Shenfang; Bao, Qiao; Mei, Hanfei; Ren, Yuanqiang
2016-05-01
For aerospace application of structural health monitoring (SHM) technology, the problem of reliable damage monitoring under time-varying conditions must be addressed and the SHM technology has to be fully validated on real aircraft structures under realistic load conditions on ground before it can reach the status of flight test. In this paper, the guided wave (GW) based SHM method is applied to a full-scale aircraft fatigue test which is one of the most similar test status to the flight test. To deal with the time-varying problem, a GW-Gaussian mixture model (GW-GMM) is proposed. The probability characteristic of GW features, which is introduced by time-varying conditions is modeled by GW-GMM. The weak cumulative variation trend of the crack propagation, which is mixed in time-varying influence can be tracked by the GW-GMM migration during on-line damage monitoring process. A best match based Kullback-Leibler divergence is proposed to measure the GW-GMM migration degree to reveal the crack propagation. The method is validated in the full-scale aircraft fatigue test. The validation results indicate that the reliable crack propagation monitoring of the left landing gear spar and the right wing panel under realistic load conditions are achieved.
Brain Wave Analysis and School Achievement.
ERIC Educational Resources Information Center
Wilson, Barry; And Others
The Brain Wave Analyzer (BWA Ertl 02) was used to measure the brain potentials of 110 public school children. Resulting scores were correlated with concurrent measures of school achievement. Results indicate that certain brain wave scores have relatively low correlations with school achievement compared to traditional intelligence measures but may…
A review of wave mechanics in the pulmonary artery with an emphasis on wave intensity analysis
Su, Junjing; Hilberg, Ole; Howard, Luke; Simonsen, Ulf; Hughes, Alun D
2016-01-01
Mean pulmonary arterial pressure and pulmonary vascular resistance remain the most common hemodynamic measures to evaluate the severity and prognosis of pulmonary hypertension. However, pulmonary vascular resistance only captures the non-oscillatory component of the right ventricular hydraulic load and neglects the dynamic compliance of the pulmonary arteries and the contribution of wave transmission. Wave intensity analysis offers an alternative way to assess the pulmonary vasculature in health and disease. Wave speed is a measure of arterial stiffness and the magnitude and timing of wave reflection provide information on the degree of impedance mismatch between the proximal and distal circulation. Studies in the pulmonary artery have demonstrated distinct differences in arterial wave propagation between individuals with and without pulmonary vascular disease. Notably, greater wave speed and greater wave reflection are observed in patients with pulmonary hypertension and in animal models exposed to hypoxia. Studying wave propagation makes a valuable contribution to the assessment of the arterial system in pulmonary hypertension and here, we briefly review the current state of knowledge of the methods used to evaluate arterial waves in the pulmonary artery. PMID:27636734
Multichannel analysis of forward scattered body waves
NASA Astrophysics Data System (ADS)
Neal, Scott Lawrence
We describe a series of innovations which are the basis for a multichannel approach to direct imaging of forward scattered body waves recorded on broadband seismic arrays. The foundation is a method through which the irregularly sampled observed seismograms are interpolated onto an arbitrarily fine grid by means of a convolution between a spatial window function and the actual station locations. The result is a weighted stack which employs all the data to compute a robust and stable multichannel estimate of the wavefield. Deconvolution of the stacked data is shown to be equivalent to a multichannel deconvolution, with spatially variable weights equal to those used in stacking. Application to data from the Lodore array in Colorado and Wyoming shows variations in crustal structure across the array and also images upper mantle discontinuities. A second innovation focuses on the design of deconvolution operators that account for the loss of high frequency components of P-to- S conversions. Two variants are presented, the first increases linearly with P-to-S lag time, the second is based on convolutional quelling and a t* attenuation model. Both methods account for the high attentuation of S waves in the upper mantle. The quelling approach however, has two advantages; it is physically based, and it provides a unified framework for the combination of stacking and deconvolution. We apply multichannel stacking to derive three quantities from the observed data and the associated receiver functions: (1) correlation between stacks of the entire array and local subarray stacks, (2) RMS amplitude of the receiver functions, and (3) Pms-to- P amplitude variations. Application of these attributes to data from recent broadband array deployments in southern Africa, Colorado and Wyoming, and the Tien Shan of central Asia shows these attributes to be highly correlated with the geology of the study areas and to be indicative of major lithospheric discontinuities beneath an array
Fast and Efficient Approach in Surface Wave Analysis
NASA Astrophysics Data System (ADS)
Kanli, A. I.
2010-12-01
Fast and Efficient Approach in Surface Wave Analysis Ali Ismet KANLI Istanbul University, Engineering Faculty, Department of Geophysical Engineering, 34320, Avcilar Campus, Istanbul-Turkey, E-mail: kanli@istanbul.edu.tr Abstract: A two-step surface wave analysis method is proposed including both the MASW (Multi-channel Analysis of Surface Waves) and Micro-tremor based techniques. This is an integrated approach and the MASW survey data are gathered to obtain the shear wave velocity-depth information up to at least 30 meters by using a special type active seismic source called as SR-II or Kangaroo. In the second step, the microtremor data which are based on surface waves from seismic noise at each site are used to determine the shear-wave velocity-depth profiles. In the second step of the process, the multichannel analysis of surface waves data are given as constraints in the microtremor inversion process. This proposed algorithm allows us to calculate shear wave velocity-depth information with all geotechnical parameters from near surface to bedrock depths very fast and efficiently.
3D Guided Wave Motion Analysis on Laminated Composites
NASA Technical Reports Server (NTRS)
Tian, Zhenhua; Leckey, Cara; Yu, Lingyu
2013-01-01
Ultrasonic guided waves have proved useful for structural health monitoring (SHM) and nondestructive evaluation (NDE) due to their ability to propagate long distances with less energy loss compared to bulk waves and due to their sensitivity to small defects in the structure. Analysis of actively transmitted ultrasonic signals has long been used to detect and assess damage. However, there remain many challenging tasks for guided wave based SHM due to the complexity involved with propagating guided waves, especially in the case of composite materials. The multimodal nature of the ultrasonic guided waves complicates the related damage analysis. This paper presents results from parallel 3D elastodynamic finite integration technique (EFIT) simulations used to acquire 3D wave motion in the subject laminated carbon fiber reinforced polymer composites. The acquired 3D wave motion is then analyzed by frequency-wavenumber analysis to study the wave propagation and interaction in the composite laminate. The frequency-wavenumber analysis enables the study of individual modes and visualization of mode conversion. Delamination damage has been incorporated into the EFIT model to generate "damaged" data. The potential for damage detection in laminated composites is discussed in the end.
NASA Astrophysics Data System (ADS)
Bidari, Pooya Sobhe; Alirezaie, Javad; Tavakkoli, Jahan
2017-03-01
This paper presents a method for modeling and simulation of shear wave generation from a nonlinear Acoustic Radiation Force Impulse (ARFI) that is considered as a distributed force applied at the focal region of a HIFU transducer radiating in nonlinear regime. The shear wave propagation is simulated by solving the Navier's equation from the distributed nonlinear ARFI as the source of the shear wave. Then, the Wigner-Ville Distribution (WVD) as a time-frequency analysis method is used to detect the shear wave at different local points in the region of interest. The WVD results in an estimation of the shear wave time of arrival, its mean frequency and local attenuation which can be utilized to estimate medium's shear modulus and shear viscosity using the Voigt model.
An improved numerical model for wave rotor design and analysis
NASA Technical Reports Server (NTRS)
Paxson, Daniel E.; Wilson, Jack
1993-01-01
A numerical model has been developed which can predict both the unsteady flows within a wave rotor and the steady averaged flows in the ports. The model is based on the assumptions of one-dimensional, unsteady, and perfect gas flow. Besides the dominant wave behavior, it is also capable of predicting the effects of finite tube opening time, leakage from the tube ends, and viscosity. The relative simplicity of the model makes it useful for design, optimization, and analysis of wave rotor cycles for any application. This paper discusses some details of the model and presents comparisons between the model and two laboratory wave rotor experiments.
An improved numerical model for wave rotor design and analysis
NASA Technical Reports Server (NTRS)
Paxson, Daniel E.; Wilson, Jack
1992-01-01
A numerical model has been developed which can predict both the unsteady flows within a wave rotor and the steady averaged flows in the ports. The model is based on the assumptions of one-dimensional, unsteady, and perfect gas flow. Besides the dominant wave behavior, it is also capable of predicting the effects of finite tube opening time, leakage from the tube ends, and viscosity. The relative simplicity of the model makes it useful for design, optimization, and analysis of wave rotor cycles for any application. This paper discusses some details of the model and presents comparisons between the model and two laboratory wave rotor experiments.
Analysis of the Giacobini-Zinner bow wave
NASA Technical Reports Server (NTRS)
Smith, E. J.; Slavin, J. A.; Bame, S. J.; Thomsen, M. F.; Cowley, S. W. H.; Richardson, I. G.; Hovestadt, D.; Ipavich, F. M.; Ogilvie, K. W.; Coplan, M. A.
1986-01-01
The cometary bow wave of P/Giacobini-Zinner has been analyzed using the complete set of ICE field and particle observations to determine if it is a shock. Changes in the magnetic field and plasma flow velocities from upstream to downstream have been analyzed to determine the direction of the normal and the propagation velocity of the bow wave. The velocity has then been compared with the fast magnetosonic wave speed upstream to derive the Mach number and establish whether it is supersonic, i.e., a shock, or subsonic, i.e., a large amplitude wave. The various measurements have also been compared with values derived from a Rankine-Hugoniot analysis. The results indicate that, inbound, the bow wave is a shock with M = 1.5. Outbound, a subsonic Mach number is obtained, however, arguments are presented that the bow wave is also likely to be a shock at this location.
Analysis of the Giacobini-Zinner bow wave
Smith, E.J.; Slavin, J.A.; Bame, S.J.; Thomsen, M.F.; Cowley, S.W.H.; Richardson, I.G.; Hovestadt, D.; Ipavich, F.M.; Ogilvie, K.W.; Coplan, M.A.
1986-01-01
The cometary bow wave of P/Giacobini-Zinner has been analyzed using the complete set of ICE field and particle observations to determine if it is a shock. Changes in the magnetic field and plasma flow velocities from upstream to downstream have been analyzed to determine the direction of the normal and the propagation velocity of the bow wave. The velocity has then been compared with the fast magnetosonic wave speed upstream to derive the Mach number and establish whether it is ''supersonic'', i.e., a shock, or ''subsonic,'' i.e., a large amplitude wave. The various measurements have also been compared with values derived from a Rankine-Hugoniot analysis. The results indicate that, inbound, the bow wave is a shock with M = 1.5. Outbound, a subsonic mach number is obtained, however, arguments are presented that the bow wave is also likely to be a shock at this location. 11 refs., 4 figs., 2 tabs.
NASA Astrophysics Data System (ADS)
Jaeger, E. F.; Berry, L. A.; Ahern, S. D.; Barrett, R. F.; Batchelor, D. B.; Carter, M. D.; D'Azevedo, E. F.; Moore, R. D.; Harvey, R. W.; Myra, J. R.; D'Ippolito, D. A.; Dumont, R. J.; Phillips, C. K.; Okuda, H.; Smithe, D. N.; Bonoli, P. T.; Wright, J. C.; Choi, M.
2006-05-01
Magnetically confined plasmas can contain significant concentrations of nonthermal plasma particles arising from fusion reactions, neutral beam injection, and wave-driven diffusion in velocity space. Initial studies in one-dimensional and experimental results show that nonthermal energetic ions can significantly affect wave propagation and heating in the ion cyclotron range of frequencies. In addition, these ions can absorb power at high harmonics of the cyclotron frequency where conventional two-dimensional global-wave models are not valid. In this work, the all-orders global-wave solver AORSA [E. F. Jaeger et al., Phys. Rev. Lett. 90, 195001 (2003)] is generalized to treat non-Maxwellian velocity distributions. Quasilinear diffusion coefficients are derived directly from the wave fields and used to calculate energetic ion velocity distributions with the CQL3D Fokker-Planck code [R. W. Harvey and M. G. McCoy, Proceedings of the IAEA Technical Committee Meeting on Simulation and Modeling of Thermonuclear Plasmas, Montreal, Canada, 1992 (USDOC NTIS Document No. DE93002962)]. For comparison, the quasilinear coefficients can be calculated numerically by integrating the Lorentz force equations along particle orbits. Self-consistency between the wave electric field and resonant ion distribution function is achieved by iterating between the global-wave and Fokker-Planck solutions.
NASA Astrophysics Data System (ADS)
Sears, T.; Singh, S. C.; Barton, P.
2007-12-01
Full waveform inversion is becoming a realistic option with the advent of modern computing facilities, both in global and exploration seismology. Over the last ten years, we have developed a series of elastic full waveform inversion algorithm and have applied to a variety of acquisition geometry. The forward modelling is based on the finite difference approximation to the full elastic wave equation in the time domain, which can incorporate converted waves, refraction, and attenuation. The inversion algorithm is based on the minimisation of observed data with synthetic data in a least-squares sense, and requires a cross-correlation of the back propagation of residual with forward propagated wavefield in a background media. Starting with the background velocity obtained using travel time inversion, we first invert wide-angle and low frequency data, which provides medium wavelength velocity structure, and then invert near offset and high frequencies that leads to high-resolution P- and S-wave velocity structure. We first invert vertical component data to obtain short wavelength P- and S-wave velocities, which are constrained by amplitude versus offset behaviour of the P-P reflection, and then invert horizontal component data to obtain very-high resolution S-wave velocity structure, which is constrained by P-S reflection. Finally, we invert all the data simultaneously to have consistency over the data and model space. We found that the high-resolution S-wave velocity image is far superior than the P-wave velocity image and provides information that may not be present in the P-wave velocity image. Combined P and S-wave velocity structure could be used to quantify sub-surface lithology and fluid saturation and pressure. In this presentation we will highlight the challenges faced during the development of our waveform inversion and their implication for the global seismology problems.
Sturtevant, Blake T; Davulis, Peter M; da Cunha, Mauricio Pereira
2009-04-01
This work reports on the determination of langatate elastic and piezoelectric constants and their associated temperature coefficients employing 2 independent methods, the pulse echo overlap (PEO) and a combined resonance technique (CRT) to measure bulk acoustic wave (BAW) phase velocities. Details on the measurement techniques are provided and discussed, including the analysis of the couplant material in the PEO technique used to couple signal to the sample, which showed to be an order of magnitude more relevant than the experimental errors involved in the data extraction. At room temperature, elastic and piezoelectric constants were extracted by the PEO and the CRT methods and showed results consistent to within a few percent for the elastic constants. Both raw acquired data and optimized constants, based on minimization routines applied to all the modes involved in the measurements, are provided and discussed. Comparison between the elastic constants and their temperature behavior with the literature reveals the recent efforts toward the consistent growth and characterization of LGT, in spite of significant variations (between 1 and 30%) among the constants extracted by different groups at room temperature. The density, dielectric permittivity constants, and respective temperature coefficients used in this work have also been independently determined based on samples from the same crystal boule. The temperature behavior of the BAW modes was extracted using the CRT technique, which has the advantage of not relying on temperature dependent acoustic couplants. Finally, the extracted temperature coefficients for the elastic and piezoelectric constants between room temperature and 120 degrees C are reported and discussed in this work.
Time-series analysis of offshore-wind-wave groupiness
Liang, H.B.
1988-01-01
This research is to applies basic time-series-analysis techniques on the complex envelope function where the study of the offshore-wind-wave groupiness is a relevant interest. In constructing the complex envelope function, a phase-unwrapping technique is integrated into the algorithm for estimating the carrier frequency and preserving the phase information for further studies. The Gaussian random wave model forms the basis of the wave-group statistics by the envelope-amplitude crossings. Good agreement between the theory and the analysis of field records is found. Other linear models, such as the individual-waves approach and the energy approach, are compared to the envelope approach by analyzing the same set of records. It is found that the character of the filter used in each approach dominates the wave-group statistics. Analyses indicate that the deep offshore wind waves are weakly nonlinear and the Gaussian random assumption remains appropriate for describing the sea state. Wave groups statistics derived from the Gaussian random wave model thus become applicable.
Bethe-Salpeter wave functions of ηc(2 S ) and ψ (2 S ) states from full lattice QCD
NASA Astrophysics Data System (ADS)
Nochi, Kazuki; Kawanai, Taichi; Sasaki, Shoichi
2016-12-01
We discuss the internal structure of radially excited charmonium mesons based on the equal-time and Coulomb gauge Bethe-Salpeter (BS) amplitudes, which are obtained in lattice QCD. Our simulations are performed with a relativistic heavy-quark action for the charm quark on the (2 +1 )-flavor PACS-CS gauge configurations at the lightest pion mass, Mπ=156 (7 ) MeV . The variational method is applied to the study of the optimal charmonium operators for ground and first excited states of S -wave charmonia. We successfully calculate the BS wave functions of ηc(2 S ) and ψ (2 S ) states, as well as ηc(1 S ) and J /ψ states, and then estimate the root-mean-square radii of both the 1 S and 2 S charmonium states. We also examine whether a series of the BS wave functions from the ground state to excited states can be described by a single set of the spin-independent and spin-dependent interquark potentials with a unique quark mass. It is found that the quark kinetic mass and both the central and the spin-spin charmonium potentials, determined from the 2 S wave functions, fairly agree with the ones from the 1 S wave functions. This strongly supports the validity of the potential description for the charmonium system—at least, below the open-charm threshold.
NASA Astrophysics Data System (ADS)
Kim, Woo Jun
A full vectorial finite element analysis is presented for the design and analysis of photonic crystal structures. Finite element C++ class libraries are developed based on the vector formulation of the two and three dimensional wave equation. Whitney 1-forms, often called edge elements, are used as basis functions to avoid spurious modes in eigenanalyses. The current finite element codes can solve 2-D and 3-D eigenvalue and scattering problems with boundary conditions: the perfect electric conductor (PEC), the perfect magnetic conductor (PMC) and the Bloch boundary condition. Open boundary problems can also be solved by implementing the perfectly matched layers (PML). Eigenanalyses are performed for various types of photonic crystal structures such as unit cells, infinite waveguides and defect cavities. The transmission spectra of the photonic crystal guiding structures, straight waveguides, waveguide bends and waveguide branches, are derived using scattering formulation. Experimental verification is also presented for a single and five missing line photonic crystal waveguides. Based on the calculated transmission spectra, we conducted simulated annealing optimization of branches and bends to increase the transmission. We applied previous results to a Mach-Zehnder type optical interferometer. The design of waveguide arms is modified to increase the sensitivity. Change of lattice constant gives rise to the shift of the waveguide band. Thus, the operating frequency can be moved to the bandedge which exhibits more dispersive characteristics. We also investigated the coupled-resonator optical waveguide (CROW) structures for the same purpose. By inserting the defect air holes in the waveguide channel, the shape and the frequency range of the band can be engineered. The increase in the sensitivity of the CROW is analyzed by varying the radii of the defect air holes in the waveguide channel. Also group velocities and their dispersion characteristics are investigated and
Millimeter-Wave Polarimetry Instrumentation and Analysis
NASA Astrophysics Data System (ADS)
Bierman, Evan M.
The chapters in this thesis roughly follow a reverse chronological order of my work in graduate school. Chapter 1 is the culmination of work with Dr. Dowell at Caltech, motivated by Professor Keating, to study polarized Galactic emission. Although the main goal of BICEP was to search for CMB B-modes, observation time was also spent on the Galactic plane region. Initially the data were collected to understand Galactic emission as a foreground of CMB polarization; however, the final paper focused on studying Galactic physics and not the CMB. Through comparison of BICEP data to other experiments, different models of the polarization production were explored. This paper also served as the initial instrument paper for the 220 GHz hardware added to BICEP for the second and third observing seasons. Chapter 2 is the software analysis work related to the paper in Chapter 1 that either did not make it into the paper or did not pan out. To explore BICEP's capabilities and produce better maps different scan strategies were explored such as full 360° scans and elevation scanning. BICEP observations are contaminated on large scales by a noise source that has not been fully identified. Different mapmaking methods were explored to remove this systematic as well as 1/ f noise and telescope systematics to maximize recovered signal. Chapter 3 represents a sample of contributions to the BICEP telescope and the UCSD FTS. To characterize the spectral response of the B ICEP telescope and the faraday rotation modulators, I helped design and construct the UCSD including layout and optical design, synthesizing wire grids, integrating the system with our lab's test cryostat, and developing software and analysis tools. My main contribution to the CMB polarization work on BICEP was analysis of calibration data. Specifically I talk about my work to understand the beams and differential pointing from observations of the Moon. Chapter 4 represents my work on Faraday Rotation devices. Initially
Dai, Yanmeng; Ren, Wenzhen; Cai, Hongbing; Ding, Huaiyi; Pan, Nan; Wang, Xiaoping
2014-04-07
Abrupt phase shift introduced by plasmonic resonances has been frequently used to design subwavelength wave plates for optical integration. Here, with the sandwich structure consisting of a top periodic patterned silver nanopatch, an in-between insulator layer and a bottom thick Au film, we realize a broadband half-wave plate which is capable to cover entire visible light spectrum ranging from 400 to 780 nm. Moreover, when the top layer is replaced with a periodic array of composite super unit cell comprised of two nanopatches with different sizes, the operation bandwidth can be further improved to exceed an octave (400-830 nm). In particular, we demonstrate that the designed half-wave plate can be used efficiently to rotate the polarization state of an ultra-fast light pulse with reserved pulse width. Our result offers a new strategy to design and construct broadband high efficiency phase-response based optical components using patterned metal nanoarray/insulator/metal structure.
Dispersive Wave Analysis Using the Chirplet Transform
Kerber, Florian; Luangvilai, Kritsakorn; Kuttig, Helge; Niethammer, Marc; Jacobs, Laurence J.
2007-03-21
Time-frequency representations (TFR) are a widely used tool to analyze signals of guided waves such as Lamb waves. As a consequence of the uncertainty principle, however, the resolution in time and frequency is limited for all existing TFR methods. Due to the multi-modal and dispersive character of Lamb waves, displacement or energy related quantities can only be allocated to individual modes when they are well-separated in the time-frequency plane.The chirplet transform (CT) has been introduced as a generalization of both the wavelet and Short-time Fourier transform (STFT). It offers additional degrees of freedom to adjust time-frequency atoms which can be exploited in a model-based approach to match the group delay of individual modes. Thus, more exact allocation of quantities of interest is possible.The objective of this research is to use a previously developed adaptive algorithm based on the CT for nondestructive evaluation. Both numerically and experimentally generated data for a single aluminum plate is analyzed to determine the accuracy and robustness of the new method in comparison the classical STFT.
Uncertainty analysis of wind-wave predictions in Lake Michigan
NASA Astrophysics Data System (ADS)
Nekouee, Navid; Ataie-Ashtiani, Behzad; Hamidi, Sajad Ahmad
2016-10-01
With all the improvement in wave and hydrodynamics numerical models, the question rises in our mind that how the accuracy of the forcing functions and their input can affect the results. In this paper, a commonly used numerical third-generation wave model, SWAN is applied to predict waves in Lake Michigan. Wind data are analyzed to determine wind variation frequency over Lake Michigan. Wave predictions uncertainty due to wind local effects are compared during a period where wind has a fairly constant speed and direction over the northern and southern basins. The study shows that despite model calibration in Lake Michigan area, the model deficiency arises from ignoring wind effects in small scales. Wave prediction also emphasizes that small scale turbulence in meteorological forces can increase prediction errors by 38%. Wave frequency and coherence analysis show that both models can predict the wave variation time scale with the same accuracy. Insufficient number of meteorological stations can result in neglecting local wind effects and discrepancies in current predictions. The uncertainty of wave numerical models due to input uncertainties and model principals should be taken into account for design risk factors.
Geotail MCA Plasma Wave Investigation Data Analysis
NASA Technical Reports Server (NTRS)
Anderson, Roger R.
1997-01-01
The primary goals of the International Solar Terrestrial Physics/Global Geospace Science (ISTP/GGS) program are identifying, studying, and understanding the source, movement, and dissipation of plasma mass, momentum, and energy between the Sun and the Earth. The GEOTAIL spacecraft was built by the Japanese Institute of Space and Astronautical Science and has provided extensive measurements of entry, storage, acceleration, and transport in the geomagnetic tail and throughout the Earth's outer magnetosphere. GEOTAIL was launched on July 24, 1992, and began its scientific mission with eighteen extensions into the deep-tail region with apogees ranging from around 60 R(sub e) to more than 208 R(sub e) in the period up to late 1994. Due to the nature of the GEOTAIL trajectory which kept the spacecraft passing into the deep tail, GEOTAIL also made 'magnetopause skimming passes' which allowed measurements in the outer magnetosphere, magnetopause, magnetosheath, bow shock, and upstream solar wind regions as well as in the lobe, magnetosheath, boundary layers, and central plasma sheet regions of the tail. In late 1994, after spending nearly 30 months primarily traversing the deep tail region, GEOTAIL began its near-Earth phase. Perigee was reduced to 10 R(sub e) and apogee first to 50 R(sub e) and finally to 30 R(sub e) in early 1995. This orbit provides many more opportunities for GEOTAIL to explore the upstream solar wind, bow shock, magnetosheath, magnetopause, and outer magnetosphere as well as the near-Earth tail regions. The WIND spacecraft was launched on November 1, 1994 and the POLAR spacecraft was launched on February 24, 1996. These successful launches have dramatically increased the opportunities for GEOTAIL and the GGS spacecraft to be used to conduct the global research for which the ISTP program was designed. The measurement and study of plasma waves have made and will continue to make important contributions to reaching the ISTP/GGS goals and solving the
multi-scale approaches for full waveform difference inversion and tomographic model analysis
NASA Astrophysics Data System (ADS)
Yuan, Y.; Simons, F. J.; Luo, Y.
2012-12-01
Tomographic Earth models are solutions to mixed-determined inverse problems, which are formulated to minimize some measure of difference between synthetics and observed data. Typically, the measurement takes the form of a cross-correlation travel-time difference, or it might be the norm of the difference between the entire waveforms, in which case every wiggle is being used to extract information from the data. Full-waveform difference tomography suffers from a slow convergence rate and a danger of converging to local minima. In this presentation, we explore several routes to improving full-waveform inversion strategies for global and regional seismic tomography. First, we will discuss a wavelet-based multi-scale approach that works progressively from low to higher scales, step-by-step involving more details of the waveform. Second, we will discuss a hybrid misfit strategy that combines cross-correlation traveltime and waveform-difference measurements. We will discuss the making of multiscale sensitivity kernels using wavelet decompositions of the seismogram. Lastly, we move to the model space to conduct a multi-scale analysis of global tomographic models using a class of 3-D spherical wavelet bases that are implemented on the ``cubed ball'', the 3-D extension of the ``cubed sphere''. Using this novel transform we study the sparsity of global seismic tomographic models via thresholded reconstruction, and characterize the relative importance and patterns of features in the Earth models via individual and cumulative reconstructions of their wavelet coefficients. Whether on the side of the data, the sensitivity kernels, or in the model space, tomographic inverse problems have much to gain from the flexibility of the wavelet decomposition in one, two and three dimensions, and this on a global, regional or exploration scale, as we show by example. Full waveform difference inversion. The first figure shows our target model with two anomalous regions. The red stars
Wave energy budget analysis in the Earth's radiation belts uncovers a missing energy
Artemyev, A.V.; Agapitov, O.V.; Mourenas, D.; Krasnoselskikh, V.V.; Mozer, F.S.
2015-01-01
Whistler-mode emissions are important electromagnetic waves pervasive in the Earth's magnetosphere, where they continuously remove or energize electrons trapped by the geomagnetic field, controlling radiation hazards to satellites and astronauts and the upper-atmosphere ionization or chemical composition. Here, we report an analysis of 10-year Cluster data, statistically evaluating the full wave energy budget in the Earth's magnetosphere, revealing that a significant fraction of the energy corresponds to hitherto generally neglected very oblique waves. Such waves, with 10 times smaller magnetic power than parallel waves, typically have similar total energy. Moreover, they carry up to 80% of the wave energy involved in wave–particle resonant interactions. It implies that electron heating and precipitation into the atmosphere may have been significantly under/over-valued in past studies considering only conventional quasi-parallel waves. Very oblique waves may turn out to be a crucial agent of energy redistribution in the Earth's radiation belts, controlled by solar activity. PMID:25975615
Meneghini, Orso; Choi, Myunghee; Volpe, Francesco
2014-02-12
An innovative millimeter wave diagnostic is proposed to measure the local magnetic field and the edge current as a function of the minor radius in the pedestal region. The idea behind such diagnostic is to localize and characterize a direction of reduced reflectivity at the O-mode cutoff layer. We modeled the wave scattering and mode-conversion processes by means of the finite-element COMSOL Multiphysics code in two dimensions (2D). Sensitivity studies were performed for parameters mocking up DIII-D plasmas. Simulations confirmed the presence of a minimum in reflectivity of an externally injected O-mode beam, and confirmed that this minimum depends on the magnetic field at the cutoff, as expected from the OX mode conversion physics. This study gives confidence in the feasibility of the diagnostic.
Asymptotic analysis of numerical wave propagation in finite difference equations
NASA Technical Reports Server (NTRS)
Giles, M.; Thompkins, W. T., Jr.
1983-01-01
An asymptotic technique is developed for analyzing the propagation and dissipation of wave-like solutions to finite difference equations. It is shown that for each fixed complex frequency there are usually several wave solutions with different wavenumbers and the slowly varying amplitude of each satisfies an asymptotic amplitude equation which includes the effects of smoothly varying coefficients in the finite difference equations. The local group velocity appears in this equation as the velocity of convection of the amplitude. Asymptotic boundary conditions coupling the amplitudes of the different wave solutions are also derived. A wavepacket theory is developed which predicts the motion, and interaction at boundaries, of wavepackets, wave-like disturbances of finite length. Comparison with numerical experiments demonstrates the success and limitations of the theory. Finally an asymptotic global stability analysis is developed.
NASA Astrophysics Data System (ADS)
Borgeaud, Anselme F. E.; Konishi, Kensuke; Kawai, Kenji; Geller, Robert J.
2016-10-01
We conduct a numerical experiment to investigate potential bias in measurements of S-wave splitting (apparent differences between the arrival times of SH and SV phases) for waves propagating close to the core-mantle boundary (CMB) in the D″ layer. The bias is defined as the discrepancy between shear wave splitting measured from finite frequency synthetic seismograms (`apparent splitting') and the splitting predicted by ray theory, which is a high-frequency approximation. For simple isotropic models, we find biases which are typically between 0.5 and 4 s, depending on the model, the Q structure and the dominant period of the synthetics. The bias increases for lower frequencies or lower Q values. The epicentral distance at which the bias starts depends on the frequency and the Q structure. We also compute synthetics for models based on mineral physics (using the elastic constants under lower-mantle pressure and temperature conditions, taking into account the phase transition from Mg-perovskite to Mg-post-perovskite) and geodynamics (the thermal boundary layer) and find that the depth of the positive velocity jump associated with the phase transition and the depth range over which the velocity decreases (due to temperature increases) in the thermal boundary layer significantly influence the wavefield in the lowermost mantle. For example, in cold regions beneath subduction zones, wavefields for SH and SV differ greatly due to the steep velocity decrease close to the CMB. For complex models, apparent splitting can also arise from the possibility that low amplitude direct phases might be overlooked, and larger amplitude later phases might instead incorrectly be picked as the direct arrival. Biases of the type investigated in this study combine with other sources of uncertainty for splitting in D″ (e.g. the correction for upper-mantle anisotropy and the difference between SH and SV ray paths) to make a precise evaluation of the anisotropy in D″ difficult.
Nonstandard Analysis and Jump Conditions for Converging Shock Waves
NASA Technical Reports Server (NTRS)
Baty, Roy S.; Farassat, Fereidoun; Tucker, Don H.
2008-01-01
Nonstandard analysis is an area of modern mathematics which studies abstract number systems containing both infinitesimal and infinite numbers. This article applies nonstandard analysis to derive jump conditions for one-dimensional, converging shock waves in a compressible, inviscid, perfect gas. It is assumed that the shock thickness occurs on an infinitesimal interval and the jump functions in the thermodynamic and fluid dynamic parameters occur smoothly across this interval. Predistributions of the Heaviside function and the Dirac delta measure are introduced to model the flow parameters across a shock wave. The equations of motion expressed in nonconservative form are then applied to derive unambiguous relationships between the jump functions for the flow parameters.
Nonstandard analysis and jump conditions for converging shock waves
NASA Astrophysics Data System (ADS)
Baty, Roy S.; Farassat, F.; Tucker, Don H.
2008-06-01
Nonstandard analysis is an area of modern mathematics that studies abstract number systems containing both infinitesimal and infinite numbers. This article applies nonstandard analysis to derive jump conditions for one-dimensional, converging shock waves in a compressible, inviscid, perfect gas. It is assumed that the shock thickness occurs on an infinitesimal interval and the jump functions in the thermodynamic and fluid dynamic parameters occur smoothly across this interval. Predistributions of the Heaviside function and the Dirac delta measure are introduced to model the flow parameters across a shock wave. The equations of motion expressed in nonconservative form are then applied to derive unambiguous relationships between the jump functions for the flow parameters.
Three-dimensional coupled mode analysis of internal-wave acoustic ducts.
Shmelev, Alexey A; Lynch, James F; Lin, Ying-Tsong; Schmidt, Henrik
2014-05-01
A fully three-dimensional coupled mode approach is used in this paper to describe the physics of low frequency acoustic signals propagating through a train of internal waves at an arbitrary azimuth. A three layer model of the shallow water waveguide is employed for studying the properties of normal modes and their coupled interaction due to the presence of nonlinear internal waves. Using a robust wave number integration technique for Fourier transform computation and a direct global matrix approach, an accurate three-dimensional coupled mode full field solution is obtained for the tonal signal propagation through straight and parallel internal waves. This approach provides accurate results for arbitrary azimuth and includes the effects of backscattering. This enables one to provide an azimuthal analysis of acoustic propagation and separate the effects of mode coupled transparent resonance, horizontal reflection and refraction, the horizontal Lloyd's mirror, horizontal ducting and anti-ducting, and horizontal tunneling and secondary ducting.
NASA Astrophysics Data System (ADS)
Lapierre, David; Alijah, Alexander; Kochanov, Roman; Kokoouline, Viatcheslav; Tyuterev, Vladimir
2016-10-01
Energies and lifetimes (widths) of vibrational states above the lowest dissociation limit of O163 were determined using a previously developed efficient approach, which combines hyperspherical coordinates and a complex absorbing potential. The calculations are based on a recently computed potential energy surface of ozone determined with a spectroscopic accuracy [Tyuterev et al., J. Chem. Phys. 139, 134307 (2013), 10.1063/1.4821638]. The effect of permutational symmetry on rovibrational dynamics and the density of resonance states in O3 is discussed in detail. Correspondence between quantum numbers appropriate for short- and long-range parts of wave functions of the rovibrational continuum is established. It is shown, by symmetry arguments, that the allowed purely vibrational (J =0 ) levels of O163 and O183, both made of bosons with zero nuclear spin, cannot dissociate on the ground-state potential energy surface. Energies and wave functions of bound states of the ozone isotopologue O163 with rotational angular momentum J =0 and 1 up to the dissociation threshold were also computed. For bound levels, good agreement with experimental energies is found: The rms deviation between observed and calculated vibrational energies is 1 cm-1. Rotational constants were determined and used for a simple identification of vibrational modes of calculated levels.
Properties of Baryons from Bonn-Gatchina Partial Wave Analysis
NASA Astrophysics Data System (ADS)
Sarantsev, Andrey
The recent results from the Bonn-Gatchinal partial wave analysis are reported. The analysis includes a large number of new pseudoscalar meson photoproduction data taken with polarized beam and target. The analysis also includes the information about photoproduction of vector mesons, which reveals resonant signals at masses above 2 GeV. The impact of the new data on spectrum of baryons and their properties is discussed.
Slow Wave Vane Structure with Elliptical Cross-Section Slots, an Analysis
NASA Technical Reports Server (NTRS)
Kosmahl, Henry G.
1994-01-01
Mathematical analysis of the wave equation in cylinders with elliptical cross-section slots was performed. Compared to slow wave structures with rectangular slots higher impedance and lower power dissipation losses are evident. These features could lead to improved designs of traveling wave magnetrons and gigahertz backward-wave oscillators as well as linear traveling wave tubes with relatively shallow slots.
Chen, Zhifeng; Yan, Yong; Li, Shufa; Xu, Xiaoguang; Jiang, Yong; Lai, Tianshu
2017-01-01
Spin-wave dynamics in full-Heusler Co2FeAl0.5Si0.5 films are studied using all-optical pump-probe magneto-optical polar Kerr spectroscopy. Backward volume magnetostatic spin-wave (BVMSW) mode is observed in films with thickness ranging from 20 to 100 nm besides perpendicular standing spin-wave (PSSW) mode, and found to be excited more efficiently than the PSSW mode. The field dependence of the effective Gilbert damping parameter appears especial extrinsic origin. The relationship between the lifetime and the group velocity of BVMSW mode is revealed. The frequency of BVMSW mode does not obviously depend on the film thickness, but the lifetime and the effective damping appear to do so. The simultaneous excitation of BVMSW and PSSW in Heusler alloy films as well as the characterization of their dynamic behaviors may be of interest for magnonic and spintronic applications. PMID:28195160
NASA Astrophysics Data System (ADS)
Dai, Jin; Dyakov, Sergey A.; Bozhevolnyi, Sergey I.; Yan, Min
2016-09-01
Metamaterials possess artificial bulk and surface electromagnetic states. Tamed dispersion properties of surface waves allow one to achieve a controllable super-Planckian radiative heat transfer (RHT) process between two closely spaced objects. We numerically demonstrate enhanced RHT between two two-dimensional grooved metal plates by a full-wave scattering approach. The enhancement originates from both transverse-magnetic spoof surface-plasmon polaritons and a series of transverse-electric bonding- and anti-bonding-waveguide modes at surfaces. The RHT spectrum is frequency selective and highly geometrically tailorable. Our simulation also reveals thermally excited nonresonant surface waves in constituent metallic materials may play a prevailing role for RHT at an extremely small separation between two metal plates, rendering metamaterial modes insignificant for the energy-transfer process.
NASA Astrophysics Data System (ADS)
Cheng, Chuyuan; Meng, Kangkang; Li, Shufa; Zhao, Jianhua; Lai, Tianshu
2013-12-01
Spin-wave dynamics in 30 nm thick Co2Fe1-xMnxAl full-Heusler films is investigated using time-resolved magneto-optical polar Kerr spectroscopy under an external field perpendicular to films. Damon-Eshbach (DE) and the first-order perpendicular standing spin-wave (PSSW) modes are observed simultaneously in four samples with x = 0, 0.3, 0.7, and 1. The frequency of DE and PSSW modes does not apparently depend on composition x, but damping of DE mode significantly on x and reaches the minimum as x = 0.7. The efficient coherent excitation of DE spin wave exhibits the promising application of Co2Fe0.3Mn0.7Al films in magnonic devices.
Fang, Yuan; Yu, Jianjun; Chi, Nan; Xiao, Jiangnan
2014-01-27
We experimentally demonstrated full-duplex bidirectional transmission of 10-Gb/s millimeter-wave (mm-wave) quadrature phase shift keying (QPSK) signal in E-band (71-76 GHz and 81-86 GHz) optical wireless link. Single-mode fibers (SMF) are connected at both sides of the antenna for uplink and downlink which realize 40-km SMF and 2-m wireless link for bidirectional transmission simultaneously. We utilized multi-level modulation format and coherent detection in such E-band optical wireless link for the first time. Mm-wave QPSK signal is generated by photonic technique to increase spectrum efficiency and received signal is coherently detected to improve receiver sensitivity. After the coherent detection, digital signal processing is utilized to compensate impairments of devices and transmission link.
NASA Astrophysics Data System (ADS)
Chen, Zhifeng; Yan, Yong; Li, Shufa; Xu, Xiaoguang; Jiang, Yong; Lai, Tianshu
2017-02-01
Spin-wave dynamics in full-Heusler Co2FeAl0.5Si0.5 films are studied using all-optical pump-probe magneto-optical polar Kerr spectroscopy. Backward volume magnetostatic spin-wave (BVMSW) mode is observed in films with thickness ranging from 20 to 100 nm besides perpendicular standing spin-wave (PSSW) mode, and found to be excited more efficiently than the PSSW mode. The field dependence of the effective Gilbert damping parameter appears especial extrinsic origin. The relationship between the lifetime and the group velocity of BVMSW mode is revealed. The frequency of BVMSW mode does not obviously depend on the film thickness, but the lifetime and the effective damping appear to do so. The simultaneous excitation of BVMSW and PSSW in Heusler alloy films as well as the characterization of their dynamic behaviors may be of interest for magnonic and spintronic applications.
Ren, Baiyang; Cho, Hwanjeong; Lissenden, Cliff J
2017-03-01
Guided waves in plate-like structures have been widely investigated for structural health monitoring. Lamb waves and shear horizontal (SH) waves, two commonly used types of waves in plates, provide different benefits for the detection of various types of defects and material degradation. However, there are few sensors that can detect both Lamb and SH waves and also resolve their modal content, namely the wavenumber-frequency spectrum. A sensor that can detect both waves is desirable to take full advantage of both types of waves in order to improve sensitivity to different discontinuity geometries. We demonstrate that polyvinylidene difluoride (PVDF) film provides the basis for a multi-element array sensor that detects both Lamb and SH waves and also measures their modal content, i.e., the wavenumber-frequency spectrum.
Ren, Baiyang; Cho, Hwanjeong; Lissenden, Cliff J.
2017-01-01
Guided waves in plate-like structures have been widely investigated for structural health monitoring. Lamb waves and shear horizontal (SH) waves, two commonly used types of waves in plates, provide different benefits for the detection of various types of defects and material degradation. However, there are few sensors that can detect both Lamb and SH waves and also resolve their modal content, namely the wavenumber-frequency spectrum. A sensor that can detect both waves is desirable to take full advantage of both types of waves in order to improve sensitivity to different discontinuity geometries. We demonstrate that polyvinylidene difluoride (PVDF) film provides the basis for a multi-element array sensor that detects both Lamb and SH waves and also measures their modal content, i.e., the wavenumber-frequency spectrum. PMID:28257065
NASA Astrophysics Data System (ADS)
Meneghini, Orso; Volpe, Francesco A.
2016-11-01
An innovative millimeter wave diagnostic is proposed to measure the local magnetic field and edge current as a function of the minor radius in the tokamak pedestal region. The idea is to identify the direction of minimum reflectivity at the O-mode cutoff layer. Correspondingly, the transmissivity due to O-X mode conversion is maximum. That direction, and the angular map of reflectivity around it, contains information on the magnetic field vector B at the cutoff layer. Probing the plasma with different wave frequencies provides the radial profile of B. Full-wave finite-element simulations are presented here in 2D slab geometry. Modeling confirms the existence of a minimum in reflectivity that depends on the magnetic field at the cutoff, as expected from mode conversion physics, giving confidence in the feasibility of the diagnostic. The proposed reflectometric approach is expected to yield superior signal-to-noise ratio and to access wider ranges of density and magnetic field, compared with related radiometric techniques that require the plasma to emit electron Bernstein waves. Due to computational limitations, frequencies of 10-20 GHz were considered in this initial study. Frequencies above the edge electron-cyclotron frequency (f > 28 GHz here) would be preferable for the experiment, because the upper hybrid resonance and right cutoff would lie in the plasma, and would help separate the O-mode of interest from spurious X-waves.
Partial Wave Analysis of Coupled Photonic Structures
NASA Technical Reports Server (NTRS)
Fuller, Kirk A.; Smith, David D.; Curreri, Peter A. (Technical Monitor)
2002-01-01
The very high quality factors sustained by microcavity optical resonators are relevant to applications in wavelength filtering, routing, switching, modulation, and multiplexing/demultiplexing. Increases in the density of photonic elements require that attention be paid to how electromagnetic (EM) coupling modifies their optical properties. This is especially true when cavity resonances are involved, in which case, their characteristics may be fundamentally altered. Understanding the optical properties of microcavities that are near or in contact with photonic elements---such as other microcavities, nanostructures, couplers, and substrates---can be expected to advance our understanding of the roles that these structures may play in VLSI photonics, biosensors and similar device technologies. Wc present results from recent theoretical studies of the effects of inter- and intracavity coupling on optical resonances in compound spherical particles. Concentrically stratified spheres and bispheres constituted from homogeneous and stratified spheres are subjects of this investigation. A new formulation is introduced for the absorption of light in an arbitrary layer of a multilayered sphere, which is based on multiple reflections of the spherical partial waves of the Lorenz-Mie solution for scattering by a sphere. Absorption efficiencies, which can be used to profile cavity resonances and to infer fluorescence yields or the onset of nonlinear optical processes in the microcavities, are presented. Splitting of resonances in these multisphere systems is paid particular attention, and consequences for photonic device development and possible performance enhancements through carefully designed architectures that exploit EM coupling are considered.
NASA Astrophysics Data System (ADS)
Bachura, Martin; Fischer, Tomas
2014-05-01
with depth, where 1/Qc seems to be frequency independent in depth range of upper lithosphere. Lateral changes of 1/Qc were also reported - it decreases in the south-west direction from the Novy Kostel focal zone, where the attenuation is the highest. Results from more advanced methods that allow for separation of scattering and intrinsic loss show that intrinsic loss is a dominant factor for attenuating of seismic waves in the region. Determination of attenuation due to scattering appears ambiguous due to small hypocentral distances available for the analysis, where the effects of scattering in frequency range from 1 to 24 Hz are not significant.
A general numerical model for wave rotor analysis
NASA Technical Reports Server (NTRS)
Paxson, Daniel W.
1992-01-01
Wave rotors represent one of the promising technologies for achieving very high core temperatures and pressures in future gas turbine engines. Their operation depends upon unsteady gas dynamics and as such, their analysis is quite difficult. This report describes a numerical model which has been developed to perform such an analysis. Following a brief introduction, a summary of the wave rotor concept is given. The governing equations are then presented, along with a summary of the assumptions used to obtain them. Next, the numerical integration technique is described. This is an explicit finite volume technique based on the method of Roe. The discussion then focuses on the implementation of appropriate boundary conditions. Following this, some results are presented which first compare the numerical approximation to the governing differential equations and then compare the overall model to an actual wave rotor experiment. Finally, some concluding remarks are presented concerning the limitations of the simplifying assumptions and areas where the model may be improved.
A general numerical model for wave rotor analysis
NASA Astrophysics Data System (ADS)
Paxson, Daniel W.
1992-07-01
Wave rotors represent one of the promising technologies for achieving very high core temperatures and pressures in future gas turbine engines. Their operation depends upon unsteady gas dynamics and as such, their analysis is quite difficult. This report describes a numerical model which has been developed to perform such an analysis. Following a brief introduction, a summary of the wave rotor concept is given. The governing equations are then presented, along with a summary of the assumptions used to obtain them. Next, the numerical integration technique is described. This is an explicit finite volume technique based on the method of Roe. The discussion then focuses on the implementation of appropriate boundary conditions. Following this, some results are presented which first compare the numerical approximation to the governing differential equations and then compare the overall model to an actual wave rotor experiment. Finally, some concluding remarks are presented concerning the limitations of the simplifying assumptions and areas where the model may be improved.
A Dynamic Analysis of Hydrodynamic Wave Journal Bearings
NASA Technical Reports Server (NTRS)
Ene, Nicoleta M.; Dimofte, Florin; Keith, Theo G.
2008-01-01
The purpose of this paper is to study the dynamic behavior of a three-wave journal bearing using a transient approach. The transient analysis permits the determination of the rotor behavior after the fractional frequency whirl appears. The journal trajectory is determined by solving a set of nonlinear equations of motion using the Runge-Katta method. The fluid film forces are computed by integrating the transient Reynolds equation at each time step location of the shaft with respect to the bearing. Because of the large values of the rotational speeds, turbulent effects were included in the computations. The influence of the temperature on the viscosity was also considered. Numerical results were compared to experimenta1 results obtained at the NASA Glenn Research Center. Comparisons of the theoretical results with experimental data were found to be in good agreement. The numerical and experimental results showed that the fluid film of a three-wave journal bearing having a diameter of 30 mm, a length of 27 mm, and a wave amplitude ratio greater than 0.15 is stable even at rotational speeds of 60,000 RPM. For lower wave amplitude ratios, the threshold speed at which the fluid film becomes unstable depends on the wave amplitude and on the supply pocket pressure. Even if the fluid film is unstable, the wave bearing maintains the whirl orbit inside the bearing clearance.
NASA Astrophysics Data System (ADS)
Ma, Jianxin; Zhang, Junjie
2015-03-01
A novel full-duplex fiber-wireless link based on single sideband (SSB) optical millimeter (mm)-wave with 10 Gbit/s 4-pulse amplitude modulation (PAM) signal is proposed to provide alternative wired and 40 GHz wireless accesses for the user terminals. The SSB optical mm-wave with 4-PAM signal consists of two tones: one bears the 4-PAM signal and the other is unmodulated with high power. After transmission over the fiber to the hybrid optical network unit (HONU), the SSB optical mm-wave signal can be decomposed by fiber Bragg gratings (FBGs) as the SSB optical mm-wave signal with reduced carrier-to-sideband ratio (the baseband 4-PAM optical signal) and the uplink optical carrier for the wireless (wired) access. This makes the HONU free from the laser source. For the uplink, since the wireless access signal is converted to the baseband by power detection, both the transmitter in the HONU and the receiver in optical line terminal (OLT) are co-shared for both wireless and wired accesses, which makes the full duplex link much simpler. In our scheme, the optical electrical field of the square-root increment level 4-PAM signal assures an equal level spacing receiving for both the downlink wired and wireless accesses. Since the downlink wireless signal is down-converted to the baseband by power detection, RF local oscillator is unnecessary. To confirm the feasibility of our proposed scheme, a simulation full duplex link with 40 GHz SSB optical mm-wave with 10 Gbit/s 4-PAM signal is built. The simulation results show that both down- and up-links for either wired or wireless access can keep good performance even if the link length of the SSMF is extended to 40 km.
Fractional Cylindrical Functions Implementation for Electromagnetic Waves Scattering Analysis
2002-09-01
IMPLEMENTATION FOR ELECTROMAGNETIC WAVES SCATTERING ANALYSIS D.V. Golovin , D.O. Batrakov. Kharkov National University, Ukraine Dmitry.O.Batrakov...N2 8. P. 1483. [2] Vorontsov A.A., Mirovitskaya S.D/I Radiotechnika i Electronika (in Russian) 1986. V.31. No 12. P. 2330. [3] Golovin D.V., Batrakov
Data synthesis and display programs for wave distribution function analysis
NASA Technical Reports Server (NTRS)
Storey, L. R. O.; Yeh, K. J.
1992-01-01
At the National Space Science Data Center (NSSDC) software was written to synthesize and display artificial data for use in developing the methodology of wave distribution analysis. The software comprises two separate interactive programs, one for data synthesis and the other for data display.
Multichannel analysis of surface waves (MASW) - Active and passive methods
Park, C.B.; Miller, R.D.; Xia, J.; Ivanov, J.
2007-01-01
The conventional seismic approaches for near-surface investigation have usually been either high-resolution reflection or refraction surveys that deal with a depth range of a few tens to hundreds meters. Seismic signals from these surveys consist of wavelets with frequencies higher than 50 Hz. The multichannel analysis of surface waves (MASW) method deals with surface waves in the lower frequencies (e.g., 1-30 Hz) and uses a much shallower depth range of investigation (e.g., a few to a few tens of meters). ?? 2007 Society of Exploration Geophysicists.
Analysis of embedded shock waves calculated by relaxation methods.
NASA Technical Reports Server (NTRS)
Murman, E. M.
1973-01-01
The requirements for uniqueness of the calculated jump conditions across embedded shock waves are investigated for type-dependent difference systems used in transonic flow studies. A mathematical analysis shows that sufficient conditions are (1) the equations should be differenced in conservative form and (2) a special difference operator should be used when switching from a hyperbolic to an elliptic operator. The latter results in a consistency condition on the integral equations, rather than the differential, at these points. Calculated jump conditions for several embedded and detached shock waves are analyzed in the physical and hodograph planes. Comparisons are made with previous results, a time-dependent calculation, and data.
Sensitive Chiral Analysis via Microwave Three-Wave Mixing
NASA Astrophysics Data System (ADS)
Patterson, David; Doyle, John M.
2013-07-01
We demonstrate chirality-induced three-wave mixing in the microwave regime, using rotational transitions in cold gas-phase samples of 1,2-propanediol and 1,3-butanediol. We show that bulk three-wave mixing, which can only be realized in a chiral environment, provides a sensitive, species-selective probe of enantiomeric excess and is applicable to a broad class of molecules. The doubly resonant condition provides simultaneous identification of species and of handedness, which should allow sensitive chiral analysis even within a complex mixture.
Full control of the spin-wave damping in a magnetic insulator using spin-orbit torque.
Hamadeh, A; d'Allivy Kelly, O; Hahn, C; Meley, H; Bernard, R; Molpeceres, A H; Naletov, V V; Viret, M; Anane, A; Cros, V; Demokritov, S O; Prieto, J L; Muñoz, M; de Loubens, G; Klein, O
2014-11-07
It is demonstrated that the threshold current for damping compensation can be reached in a 5 μm diameter YIG(20 nm)|Pt(7 nm) disk. The demonstration rests upon the measurement of the ferromagnetic resonance linewidth as a function of I(dc) using a magnetic resonance force microscope (MRFM). It is shown that the magnetic losses of spin-wave modes existing in the magnetic insulator can be reduced or enhanced by at least a factor of 5 depending on the polarity and intensity of an in-plane dc current I(dc) flowing through the adjacent normal metal with strong spin-orbit interaction. Complete compensation of the damping of the fundamental mode by spin-orbit torque is reached for a current density of ∼3×10(11) A·m(-2), in agreement with theoretical predictions. At this critical threshold the MRFM detects a small change of static magnetization, a behavior consistent with the onset of an auto-oscillation regime.
Huang, Norden E.; Hu, Kun; Yang, Albert C. C.; Chang, Hsing-Chih; Jia, Deng; Liang, Wei-Kuang; Yeh, Jia Rong; Kao, Chu-Lan; Juan, Chi-Hung; Peng, Chung Kang; Meijer, Johanna H.; Wang, Yung-Hung; Long, Steven R.; Wu, Zhauhua
2016-01-01
The Holo-Hilbert spectral analysis (HHSA) method is introduced to cure the deficiencies of traditional spectral analysis and to give a full informational representation of nonlinear and non-stationary data. It uses a nested empirical mode decomposition and Hilbert–Huang transform (HHT) approach to identify intrinsic amplitude and frequency modulations often present in nonlinear systems. Comparisons are first made with traditional spectrum analysis, which usually achieved its results through convolutional integral transforms based on additive expansions of an a priori determined basis, mostly under linear and stationary assumptions. Thus, for non-stationary processes, the best one could do historically was to use the time–frequency representations, in which the amplitude (or energy density) variation is still represented in terms of time. For nonlinear processes, the data can have both amplitude and frequency modulations (intra-mode and inter-mode) generated by two different mechanisms: linear additive or nonlinear multiplicative processes. As all existing spectral analysis methods are based on additive expansions, either a priori or adaptive, none of them could possibly represent the multiplicative processes. While the earlier adaptive HHT spectral analysis approach could accommodate the intra-wave nonlinearity quite remarkably, it remained that any inter-wave nonlinear multiplicative mechanisms that include cross-scale coupling and phase-lock modulations were left untreated. To resolve the multiplicative processes issue, additional dimensions in the spectrum result are needed to account for the variations in both the amplitude and frequency modulations simultaneously. HHSA accommodates all the processes: additive and multiplicative, intra-mode and inter-mode, stationary and non-stationary, linear and nonlinear interactions. The Holo prefix in HHSA denotes a multiple dimensional representation with both additive and multiplicative capabilities. PMID:26953180
Huang, Norden E; Hu, Kun; Yang, Albert C C; Chang, Hsing-Chih; Jia, Deng; Liang, Wei-Kuang; Yeh, Jia Rong; Kao, Chu-Lan; Juan, Chi-Hung; Peng, Chung Kang; Meijer, Johanna H; Wang, Yung-Hung; Long, Steven R; Wu, Zhauhua
2016-04-13
The Holo-Hilbert spectral analysis (HHSA) method is introduced to cure the deficiencies of traditional spectral analysis and to give a full informational representation of nonlinear and non-stationary data. It uses a nested empirical mode decomposition and Hilbert-Huang transform (HHT) approach to identify intrinsic amplitude and frequency modulations often present in nonlinear systems. Comparisons are first made with traditional spectrum analysis, which usually achieved its results through convolutional integral transforms based on additive expansions of an a priori determined basis, mostly under linear and stationary assumptions. Thus, for non-stationary processes, the best one could do historically was to use the time-frequency representations, in which the amplitude (or energy density) variation is still represented in terms of time. For nonlinear processes, the data can have both amplitude and frequency modulations (intra-mode and inter-mode) generated by two different mechanisms: linear additive or nonlinear multiplicative processes. As all existing spectral analysis methods are based on additive expansions, either a priori or adaptive, none of them could possibly represent the multiplicative processes. While the earlier adaptive HHT spectral analysis approach could accommodate the intra-wave nonlinearity quite remarkably, it remained that any inter-wave nonlinear multiplicative mechanisms that include cross-scale coupling and phase-lock modulations were left untreated. To resolve the multiplicative processes issue, additional dimensions in the spectrum result are needed to account for the variations in both the amplitude and frequency modulations simultaneously. HHSA accommodates all the processes: additive and multiplicative, intra-mode and inter-mode, stationary and non-stationary, linear and nonlinear interactions. The Holo prefix in HHSA denotes a multiple dimensional representation with both additive and multiplicative capabilities.
NASA Technical Reports Server (NTRS)
Huang, Norden E.; Hu, Kun; Yang, Albert C. C.; Chang, Hsing-Chih; Jia, Deng; Liang, Wei-Kuang; Yeh, Jia Rong; Kao, Chu-Lan; Juan, Chi-Huang; Peng, Chung Kang; Meijer, Johanna H.; Wang, Yung-Hung; Long, Steven R.; Wu, Zhauhua
2016-01-01
The Holo-Hilbert spectral analysis (HHSA) method is introduced to cure the deficiencies of traditional spectral analysis and to give a full informational representation of nonlinear and non-stationary data. It uses a nested empirical mode decomposition and Hilbert-Huang transform (HHT) approach to identify intrinsic amplitude and frequency modulations often present in nonlinear systems. Comparisons are first made with traditional spectrum analysis, which usually achieved its results through convolutional integral transforms based on additive expansions of an a priori determined basis, mostly under linear and stationary assumptions. Thus, for non-stationary processes, the best one could do historically was to use the time- frequency representations, in which the amplitude (or energy density) variation is still represented in terms of time. For nonlinear processes, the data can have both amplitude and frequency modulations (intra-mode and inter-mode) generated by two different mechanisms: linear additive or nonlinear multiplicative processes. As all existing spectral analysis methods are based on additive expansions, either a priori or adaptive, none of them could possibly represent the multiplicative processes. While the earlier adaptive HHT spectral analysis approach could accommodate the intra-wave nonlinearity quite remarkably, it remained that any inter-wave nonlinear multiplicative mechanisms that include cross-scale coupling and phase-lock modulations were left untreated. To resolve the multiplicative processes issue, additional dimensions in the spectrum result are needed to account for the variations in both the amplitude and frequency modulations simultaneously. HHSA accommodates all the processes: additive and multiplicative, intra-mode and inter-mode, stationary and nonstationary, linear and nonlinear interactions. The Holo prefix in HHSA denotes a multiple dimensional representation with both additive and multiplicative capabilities.
Data Analysis Technologies to Reduce Risk in Future Gravitational-Wave Missions
NASA Astrophysics Data System (ADS)
Littenberg, Tyson
The existence of gravitational waves has at last been confirmed by the LIGO/Virgo discovery of a binary black hole merger, heralding the beginning of a new fields of research in observational astronomy, astrophysics, and relativity research. the LISA Pathfinder mission has begun collecting science data, paving the way for space-based gravitational wave measurement. Gravitational wave science will reach its full potential with a space-based observatory able to access mHz frequencies. The proposed work will investigate how develop crucial data analysis infrastructure for a future space mission. The three key themes of the proposal are (i) to incorporate lessons learned from LISA Pathfinder into our understanding of a GW observatories performance, (ii) develop data analysis mcethods for inter-spacecraft ranging critical to achieving the measurement precision needed for GW detection, and (iii) explore how known sources in the mHz band can be used as calibration sources.
1993-08-27
SECURITY CLASSIFICATION AUTHORITY 3 DISTRIBUTION/AVAILABILITY OF REPORT 2b DECLASSIFICATION i DOWNGRADING SCHEDULE UNLIMITED 4. PERFORMING...NO. 11 TITLE (Include Security Classfication) Extension of OSRC to Full-Vector Electromagnetic Wave Scattering (UNCLASSIFIED) 12 PERSONAL AUTHOR (S... authors wish to thank the referees for their constructive remarks. They also wish to thank Mr. Thomas Moore for his Vii. RELATION TO PREVIOUS HIGH
Guided Wave Delamination Detection and Quantification With Wavefield Data Analysis
NASA Technical Reports Server (NTRS)
Tian, Zhenhua; Campbell Leckey, Cara A.; Seebo, Jeffrey P.; Yu, Lingyu
2014-01-01
Unexpected damage can occur in aerospace composites due to impact events or material stress during off-nominal loading events. In particular, laminated composites are susceptible to delamination damage due to weak transverse tensile and inter-laminar shear strengths. Developments of reliable and quantitative techniques to detect delamination damage in laminated composites are imperative for safe and functional optimally-designed next-generation composite structures. In this paper, we investigate guided wave interactions with delamination damage and develop quantification algorithms by using wavefield data analysis. The trapped guided waves in the delamination region are observed from the wavefield data and further quantitatively interpreted by using different wavenumber analysis methods. The frequency-wavenumber representation of the wavefield shows that new wavenumbers are present and correlate to trapped waves in the damage region. These new wavenumbers are used to detect and quantify the delamination damage through the wavenumber analysis, which can show how the wavenumber changes as a function of wave propagation distance. The location and spatial duration of the new wavenumbers can be identified, providing a useful means not only for detecting the presence of delamination damage but also allowing for estimation of the delamination size. Our method has been applied to detect and quantify real delamination damage with complex geometry (grown using a quasi-static indentation technique). The detection and quantification results show the location, size, and shape of the delamination damage.
Analysis methods for burst gravitational waves with TAMA data
NASA Astrophysics Data System (ADS)
Ando, Masaki; Arai, K.; Nagano, S.; Takahashi, R.; Sato, S.; Tatsumi, D.; Tsunesada, Y.; Kanda, N.; Kawamura, S.; Beyersdorf, P.; Zhu, Zonh-Hong; Numata, K.; Iida, Y.; Aso, Y.; Mio, N.; Moriwaki, S.; Somiya, K.; Miyoki, S.; Kondo, K.; Takahashi, H.; Hayama, K.; Tagoshi, H.; Fujimoto, M.-K.; Tsubono, K.; Kuroda, K.; TAMA Collaboration
2004-10-01
We describe analysis methods and results for burst gravitational waves with data obtained in the eighth observation run by the TAMA300 detector. In this analysis, we used an excess-power filter for signal detection, and two types of veto for fake-event rejection; one is a time-scale selection of events and the other is a veto with auxiliary information recorded together with the main signal. We generated an event-candidate list with this analysis procedure, which will be used for coincidence analysis with the other detectors.
Affective Outcomes of Schooling: Full-Information Item Factor Analysis of a Student Questionnaire.
ERIC Educational Resources Information Center
Muraki, Eiji; Engelhard, George, Jr.
Recent developments in dichotomous factor analysis based on multidimensional item response models (Bock and Aitkin, 1981; Muthen, 1978) provide an effective method for exploring the dimensionality of questionnaire items. Implemented in the TESTFACT program, this "full information" item factor analysis accounts not only for the pairwise joint…
Multichannel analysis of surface wave method with the autojuggie
Tian, G.; Steeples, D.W.; Xia, J.; Miller, R.D.; Spikes, K.T.; Ralston, M.D.
2003-01-01
The shear (S)-wave velocity of near-surface materials and its effect on seismic-wave propagation are of fundamental interest in many engineering, environmental, and groundwater studies. The multichannel analysis of surface wave (MASW) method provides a robust, efficient, and accurate tool to observe near-surface S-wave velocity. A recently developed device used to place large numbers of closely spaced geophones simultaneously and automatically (the 'autojuggie') is shown here to be applicable to the collection of MASW data. In order to demonstrate the use of the autojuggie in the MASW method, we compared high-frequency surface-wave data acquired from conventionally planted geophones (control line) to data collected in parallel with the automatically planted geophones attached to steel bars (test line). The results demonstrate that the autojuggie can be applied in the MASW method. Implementation of the autojuggie in very shallow MASW surveys could drastically reduce the time required and costs incurred in such surveys. ?? 2003 Elsevier Science Ltd. All rights reserved.
Dynamic mode decomposition analysis of detonation waves
NASA Astrophysics Data System (ADS)
Massa, L.; Kumar, R.; Ravindran, P.
2012-06-01
Dynamic mode decomposition is applied to study the self-excited fluctuations supported by transversely unstable detonations. The focus of this study is on the stability of the limit cycle solutions and their response to forcing. Floquet analysis of the unforced conditions reveals that the least stable perturbations are almost subharmonic with ratio between global mode and fundamental frequency λi/ωf = 0.47. This suggests the emergence of period doubling modes as the route to chaos observed in larger systems. The response to forcing is analyzed in terms of the coherency of the four fundamental energy modes: acoustic, entropic, kinetic, and chemical. Results of the modal decomposition suggest that the self-excited oscillations are quite insensitive to vortical forcing, and maintain their coherency up to a forcing turbulent Mach number of 0.3.
Impedance-matching analysis in IR leaky-wave antennas
NASA Astrophysics Data System (ADS)
Premkumar, Navaneeth; Xu, Yuancheng; Lail, Brian A.
2015-08-01
Planar leaky-wave antennas (LWA) that are capable of full-space scanning have long since been the pursuit for applications including, but not limited to, integration onto vehicles and into cameras for wide-angle of view beam-steering. Such a leaky-wave surface (LWS) was designed for long-wave infrared frequencies with frequency scanning capability. The LWS is based on a microstrip patch array design of a leaky-wave impedance surface and is made up of gold microstrip patches on a grounded zinc sulphide substrate. A 1D composite right/left-handed (CRLH) metamaterial made by periodically stacking a unit cell of the LWS in the longitudinal direction to form a LWA was designed. This paper deals with loading the LWA with a nickel bolometer to collect leaky-wave signals. The LWA radiates a backward leaking wave at 30 degrees at 28.3THz and scans through broadside for frequencies 20THz through 40THz. The paper deals with effectively placing the bolometer in order for the collected signal to exhibit the designed frequency regime. An effective way to maximize the power coupling into the load from the antenna is also explored. The benefit of such a metamaterial/holographic antennacoupled detector is its ability to provide appreciable capture cross-sections while delivering smart signals to subwavelength sized detectors. Due to their high-gain, low-profile, fast response time of the detector and ease of fabrication, this IR LWA-coupled bolometer harbors great potential in the areas of high resolution, uncooled, infrared imaging.
NASA Astrophysics Data System (ADS)
Parker, L.; Mellors, R. J.; Thurber, C. H.; Wang, H. F.; Zeng, X.
2015-12-01
A 762-meter Distributed Acoustic Sensing (DAS) array with a channel spacing of one meter was deployed at the Garner Valley Downhole Array in Southern California. The array was approximately rectangular with dimensions of 180 meters by 80 meters. The array also included two subdiagonals within the rectangle along which three-component geophones were co-located. Several active sources were deployed, including a 45-kN, swept-frequency, shear-mass shaker, which produced strong Rayleigh waves across the array. Both DAS and geophone traces were filtered in 2-Hz steps between 4 and 20 Hz to obtain phase velocities as a function of frequency from fitting the moveout of travel times over distances of 35 meters or longer. As an alternative to this traditional means of finding phase velocity, it is theoretically possible to find the Rayleigh-wave phase velocity at each point of co-location as the ratio of DAS and geophone responses, because DAS is sensitive to ground strain and geophones are sensitive to ground velocity, after suitable corrections for instrument response (Mikumo & Aki, 1964). The concept was tested in WPP, a seismic wave propagation program, by first validating and then using a 3D synthetic, full-waveform seismic model to simulate the effect of increased levels of noise and uncertainty as data go from ideal to more realistic. The results obtained from this study provide a better understanding of the DAS response and its potential for being combined with traditional seismometers for obtaining phase velocity at a single location. This analysis is part of the PoroTomo project (Poroelastic Tomography by Adjoint Inverse Modeling of Data from Seismology, Geodesy, and Hydrology, http://geoscience.wisc.edu/feigl/porotomo).
NASA Astrophysics Data System (ADS)
Abdul-Gaffoor, Mohammed Rajeek
2000-09-01
A simple method to model Printed Circuit Board (PCB) that takes advantage of the unique features found in PCBs is proposed. This method is capable of analyzing coupling between any nets in the entire multilayer PCB. Using the equivalence principle, the PCB is modeled as a cascade of parallel plate waveguides with half-space regions residing above and below the PCB. The problem is formulated using equivalent magnetic currents in the non- metallic regions of layer interfaces rather than in terms of electric currents in the planar metal layers. The equivalent magnetic currents at the dielectric interfaces are expressed in terms of the Rao-Wilton-Glisson (RWG) basis functions. The electric currents flowing on the vias inside dielectric layers are assumed constant in the vertical direction. These vertical electric currents radiate TEM modes in the parallel plate environment. Integral equations based on simple parallel plate and free-space Green's functions enforcing the boundary conditions are set up and solved using the Method of Moments. The equivalent magnetic currents in each layer interact only with currents in the adjacent layers, thereby resulting in a `` chained-block- banded'' matrix. Excitation is provided through ports defined at each pair of pads, or between a pad and nearby ground. These ports are located on the top and the bottom layers of the PCB where the circuit components and IC pins are mounted. Two different localized excitation schemes, one with a current loop injection and the other with a strip current excitation, are proposed. This formulation requires the computation of the MoM matrix once per frequency for any number of ports. Further, the solution for only those unknown equivalent magnetic currents around the port regions is required to obtain the N-port impedance parameter characterization of the PCB. Consequently, a memory efficient block matrix solution process can be used to solve problems of a large size for a given memory. Simple and realistic examples are given to illustrate the validity and efficiency of this approach.
Analysis of Metric Type II Burst and EUV Waves Generated by Shock Wave Driven by Cme
NASA Astrophysics Data System (ADS)
Cunha-Silva, Rafael; Fernandes, Francisco; Selhorst, Caius
2016-07-01
The relationship between solar type II radio bursts produced by plasma oscillations and coronal shocks is well shown since the 1960s. However, the details of the association between the drivers of the shocks and the metric type II bursts remains a controversial issue. The flares and the coronal mass ejections (CMEs) are the potential drivers of these shocks. In this work, we present the analysis of a metric type II burst observed on May 17, 2013, by spectrometers from e-CALLISTO network and EUV images from the Extreme Ultraviolet Imager (EUVI), aboard the STEREO. The event was associated with an M3.2 X-ray flare and a halo CME. The EUV images show the EUV wave was produced by the expansion of the CME. The heights of the EUV wave fronts and the magnetic field intensity determined in the regions of the shock are consistent with those the heights of radio source obtained with the three-fold Newkirk density model, which suggests an oblique propagation of the shock. The finding of an accelerating shock with speed of 530-640 km/s and of 870-1220 km/s for the first and the second stages of the type II emission, respectively, is consistent with both the average speed of the associated EUV wave front, of 626 km/s, during the initial expansion of the CME, and with the linear speed of the CME, of 1345 km/s. These results will be presented and discussed.
Linear analysis of a backward wave oscillator with triangular corrugated slow wave structure
NASA Astrophysics Data System (ADS)
Saber, Md. Ghulam; Sagor, Rakibul Hasan; Amin, Md. Ruhul
2016-05-01
In this work, a backward wave oscillator (BWO) with triangularly corrugated periodic metallic slow wave structure (TrCSWS) driven by an infinitely thin annular electron beam is studied using linear theory. The electron beam is assumed to be guided by a strong magnetic field. The triangular axial profile of the SWS is approximated by a Fourier series in order to apply the linear Rayleigh-Fourier (R-F) theory that has long been used in the theoretical analysis of BWOs with sinusoidally corrugated SWS (SCSWS). The dispersion equation for various beam parameters has been solved and the temporal growth rate (TGR) of the electromagnetic wave for the fundamental TM_{01} mode is calculated numerically. The TGR values for different beam parameters have been compared with those of the BWO with SCSWS, semi-circularly corrugated SWS (SCCSWS) and trapezoidally corrugated SWS (TCSWS). In order to compare the TGR values, the amplitude of corrugation of the TrCSWS is varied so that its dispersion curve of TM_{01} mode almost coincides with that of the SCSWS and TCSWS. The study reveals that the performance (in terms of TGR) of the proposed BWO with TrCSWS is comparable to that of other BWOs with SCSWS and TCSWS for the same set of beam parameters and it provides significantly better performance than SCCSWS. So, the proposed TrCSWS that can easily be constructed may replace SCSWS, SCCSWS or TCSWS as their viable alternative.
Full-waveform analysis of soil and sensor characteristics on EMI sensitivity and investigation depth
NASA Astrophysics Data System (ADS)
André, Frédéric; Moghadas, Davood; Vereecken, Harry; Lambot, Sébastien
2010-05-01
, leading to erroneous analyses and data interpretation if not properly accounted for. We conducted synthetic experiments in order to investigate and quantify the effects of the different factors likely to affect EMI sensor vertical spatial sensitivity and investigation depth and to identify conditions for which the LIN approximation holds. The EMI signal was modelled from an exact solution of the three-dimensional Maxwell's equations for wave propagation in a horizontally multilayered medium. For this analysis, we examined different configurations for a two-layered subsurface, considering contrasted values for the two layer electrical conductivities within the range encountered for soils and varying the thickness of the first layer. For each of these configurations, several frequencies and transmitter-receiver coil separations were studied, encompassing the ranges of corresponding parameters found for the current EMI systems. Moreover, the effects of the orientation and of the height of the instrument above the soil surface were also analysed. These results bring interesting insights on the influence of both soil and sensor characteristics on the sensitivity with depth of the EMI signal and on the investigation depth, and point out situations for which the LIN approximation should be carefully considered. This study situates in the framework of the development of a new EMI approach, based on zero-offset co-planar coils and full-waveform inversion for exact parameter retrieval.
Comprehensive Analysis of Coronal Mass Ejection Mass and Energy Properties Over a Full Solar Cycle
2010-01-01
the evolution of the solar corona and coronal mass ejections (CMEs) over a full solar cycle with high quality images and regular cadence. This is the...observed the evolution of the solar corona and coronal mass ejections (CMEs) over a full solar cycle with high quality images and regular cadence. This is...1985) and Vourlidas et al. (2002). We discuss several aspects that emerge from the statistical analysis of such a large event sample such as solar
Direct Calculation of the Scattering Amplitude Without Partial Wave Analysis
NASA Technical Reports Server (NTRS)
Shertzer, J.; Temkin, A.; Fisher, Richard R. (Technical Monitor)
2001-01-01
Two new developments in scattering theory are reported. We show, in a practical way, how one can calculate the full scattering amplitude without invoking a partial wave expansion. First, the integral expression for the scattering amplitude f(theta) is simplified by an analytic integration over the azimuthal angle. Second, the full scattering wavefunction which appears in the integral expression for f(theta) is obtained by solving the Schrodinger equation with the finite element method (FEM). As an example, we calculate electron scattering from the Hartree potential. With minimal computational effort, we obtain accurate and stable results for the scattering amplitude.
NASA Astrophysics Data System (ADS)
Schumacher, Florian; Friederich, Wolfgang
Due to increasing computational resources, the development of new numerically demanding methods and software for imaging Earth's interior remains of high interest in Earth sciences. Here, we give a description from a user's and programmer's perspective of the highly modular, flexible and extendable software package ASKI-Analysis of Sensitivity and Kernel Inversion-recently developed for iterative scattering-integral-based seismic full waveform inversion. In ASKI, the three fundamental steps of solving the seismic forward problem, computing waveform sensitivity kernels and deriving a model update are solved by independent software programs that interact via file output/input only. Furthermore, the spatial discretizations of the model space used for solving the seismic forward problem and for deriving model updates, respectively, are kept completely independent. For this reason, ASKI does not contain a specific forward solver but instead provides a general interface to established community wave propagation codes. Moreover, the third fundamental step of deriving a model update can be repeated at relatively low costs applying different kinds of model regularization or re-selecting/weighting the inverted dataset without need to re-solve the forward problem or re-compute the kernels. Additionally, ASKI offers the user sensitivity and resolution analysis tools based on the full sensitivity matrix and allows to compose customized workflows in a consistent computational environment. ASKI is written in modern Fortran and Python, it is well documented and freely available under terms of the GNU General Public License (http://www.rub.de/aski).
A Two-Tier Full-Information Item Factor Analysis Model with Applications
ERIC Educational Resources Information Center
Cai, Li
2010-01-01
Motivated by Gibbons et al.'s (Appl. Psychol. Meas. 31:4-19, "2007") full-information maximum marginal likelihood item bifactor analysis for polytomous data, and Rijmen, Vansteelandt, and De Boeck's (Psychometrika 73:167-182, "2008") work on constructing computationally efficient estimation algorithms for latent variable…
ERIC Educational Resources Information Center
Donovan, Phillip Raymond
2009-01-01
This study focuses on the analysis of the behavior of unbound aggregates to offset wheel loads. Test data from full-scale aircraft gear loading conducted at the National Airport Pavement Test Facility (NAPTF) by the Federal Aviation Administration (FAA) are used to investigate the effects of wander (offset loads) on the deformation behavior of…
D'Onza, Giuseppe; Greco, Giulio; Allegrini, Marco
2016-02-01
Recycling implies additional costs for separated municipal solid waste (MSW) collection. The aim of the present study is to propose and implement a management tool - the full cost accounting (FCA) method - to calculate the full collection costs of different types of waste. Our analysis aims for a better understanding of the difficulties of putting FCA into practice in the MSW sector. We propose a FCA methodology that uses standard cost and actual quantities to calculate the collection costs of separate and undifferentiated waste. Our methodology allows cost efficiency analysis and benchmarking, overcoming problems related to firm-specific accounting choices, earnings management policies and purchase policies. Our methodology allows benchmarking and variance analysis that can be used to identify the causes of off-standards performance and guide managers to deploy resources more efficiently. Our methodology can be implemented by companies lacking a sophisticated management accounting system.
Wave function analysis of MHC-peptide interactions.
Cárdenas, Constanza; Obregón, Mateo; Balbín, Alejandro; Villaveces, José Luis; Patarroyo, Manuel E
2007-01-01
We have carried out an analysis of the wave function data for three MHC-peptide complexes: HLA-DRbeta1*0101-HA, HLA-DRbeta1*0401-HA and HLA-DRbeta1*0401-Col. We used quantum chemistry computer programs to generate wave function coefficients for these complexes, from which we obtained both molecular and atomic orbital data for both pocket and peptide amino acids within each pocket region. From these discriminated data, interaction molecular orbitals (IMOs) were identified as those with large and similar atomic orbital coefficient contributions from both pocket and peptide amino acids. The present results correlate well with our previous research where only electrostatic moments were used to explore molecular component interactions. Furthermore, we show a quantum chemical methodology to produce more fine-grained results concerning amino acid behavior in the MHC-peptide interaction.
Linking Science Analysis with Observation Planning: A Full Circle Data Lifecycle
NASA Technical Reports Server (NTRS)
Grosvenor, Sandy; Jones, Jeremy; Koratkar, Anuradha; Li, Connie; Mackey, Jennifer; Neher, Ken; Wolf, Karl; Obenschain, Arthur F. (Technical Monitor)
2001-01-01
A clear goal of the Virtual Observatory (VO) is to enable new science through analysis of integrated astronomical archives. An additional and powerful possibility of the VO is to link and integrate these new analyses with planning of new observations. By providing tools that can be used for observation planning in the VO, the VO will allow the data lifecycle to come full circle: from theory to observations to data and back around to new theories and new observations. The Scientist's Expert Assistant (SEA) Simulation Facility (SSF) is working to combine the ability to access existing archives with the ability to model and visualize new observations. Integrating the two will allow astronomers to better use the integrated archives of the VO to plan and predict the success of potential new observations more efficiently, The full circle lifecycle enabled by SEA can allow astronomers to make substantial leaps in the quality of data and science returns on new observations. Our paper examines the exciting potential of integrating archival analysis with new observation planning, such as performing data calibration analysis on archival images and using that analysis to predict the success of new observations, or performing dynamic signal-to-noise analysis combining historical results with modeling of new instruments or targets. We will also describe how the development of the SSF is progressing and what have been its successes and challenges.
Theoretical analysis of the kinetic performance of laboratory- and full-scale composting systems.
Baptista, Marco; Silveira, Ana; Antunes, Fernando
2012-07-01
Composting research at laboratory-scale is critical for the development of optimized full-scale plants. Discrepancies between processes at laboratory-scale and full-scale systems have been investigated in terms of heat balances, but a kinetic analysis of this issue is still missing. In this study, the composting rate at laboratory-scale was, on average, between 1.9 and 5.7 times faster than in full-scale systems for a set of published studies using municipal solid waste, food waste or similar materials. Laboratory-scale performance and full-scale systems were limited to 71 and 46%, respectively, of their maximum potential due to poor management of environmental process conditions far from their optimum. The main limiting environmental factor was found to be moisture content, followed by temperature. Besides environmental factors, waste composition and particle size were identified as factors accounting for kinetic differences between laboratory- and full-scale systems. Overall, this study identifies those factors that affect the kinetics of the composting process most and revealed a significant margin for reducing process time in full-scale composting.
Hydroelastic analysis of ice shelves under long wave excitation
NASA Astrophysics Data System (ADS)
Papathanasiou, Theodosios; Karperaki, Angeliki; Theotokoglou, Efstathios; Belibassakis, Kostas
2014-05-01
The transient hydroelastic response of an ice shelf, under long wave forcing, is analysed by means of the Finite Element method. Our main goal is to provide a simple model for tsunami wave - ice shelf interaction, capable of reproducing, in an at least qualitative manner, the stress field induced in the ice shelf, when excited by a tsunami wave. The analysis is aimed to model ice calving caused by wave impact, as was the case after the Honsu 2011 incident [1]. Adopting several simplifying but realistic assumptions, the ice shelf is modeled as a variable thickness, Euler-Bernoulli, cantilever beam, while the 1+1 linear shallow water equations are employed for the hydrodynamic field representation, as described in [2]. The fixed cantilever beam resembles a constrained, continuous ice shelf extending into the ocean. The solution of such a system, for a freely floating plate, has been presented by Sturova [3], where a modal expansion of the hydroelastic response with respect to the dry modes of the beam has been used. Our solution approach is based on the development of a special hydroelastic finite element for the governing equations. Cases of constant and variable bathymetry are considered. Bending moment time profiles yield the maximum tensile stress at the upper and lower surfaces of the ice shelf, which is the critical parameter for crack initiation or propagation. As expected, maximum absolute bending moment values appear at the base of the ice shelf, where no deflection or rotation occurs. The fact that the wave is fully reflected on the vertical impermeable boundary, corresponding to the continental shelf under the base of the floe, leads to extreme focusing and thus extreme bending moment values. Finally, the case of cracked shelves has been considered with use of the elementary defective beam theory of Kienzler and Herrmann [4]. Future enhancement of the present model is proposed on the grounds of a higher order beam/plate theory and a 2-D formulation
Full-length high-temperature severe fuel damage test No. 2. Final safety analysis
Hesson, G.M.; Lombardo, N.J.; Pilger, J.P.; Rausch, W.N.; King, L.L.; Hurley, D.E.; Parchen, L.J.; Panisko, F.E.
1993-09-01
Hazardous conditions associated with performing the Full-Length High- Temperature (FLHT). Severe Fuel Damage Test No. 2 experiment have been analyzed. Major hazards that could cause harm or damage are (1) radioactive fission products, (2) radiation fields, (3) reactivity changes, (4) hydrogen generation, (5) materials at high temperature, (6) steam explosion, and (7) steam pressure pulse. As a result of this analysis, it is concluded that with proper precautions the FLHT- 2 test can be safely conducted.
Pulse wave analysis for the prediction of preeclampsia.
Carty, D M; Neisius, U; Rooney, L K; Dominiczak, A F; Delles, C
2014-02-01
Preeclampsia is associated with a number of changes to maternal vascular function. Assessment of arterial stiffness using pulse wave analysis (PWA) has been proposed as a means of predicting preeclampsia before the onset of clinically detectable disease. One hundred and eighty women with 2 risk factors for preeclampsia were examined at gestational weeks 16 and 28, of whom 17 (9.4%) developed preeclampsia. To study the effects of pregnancy itself women were also examined at 6-9 months post-natally; an additional 30 healthy non-pregnant women were also examined. PWA was performed using SphygmoCor; augmentation index (AIx), a marker of arterial wave reflection, was also measured using EndoPAT-2000. Women who developed preeclampsia were more likely to be overweight and had a higher brachial and central diastolic BP at gestational week 16 than those who remained normotensive. There was no difference in any parameter of arterial wave reflection between non-pregnant and pregnant women, nor between those who developed preeclampsia and those who remained normotensive, when examined at weeks 16 and 28 or post-natally. In this cohort of women with risk factors for preeclampsia, PWA did not provide additional information beyond brachial blood pressure and maternal risk factor profile about the risk of future development of preeclampsia.
Xu, Min Li; Li, Bao Qiong; Wang, Xue; Chen, Jing; Zhai, Hong Lin
2016-08-01
Although liquid chromatography with mass spectrometry in full scan mode can obtain all the signals simultaneously in a large range and low cost, it is rarely used in quantitative analysis due to several problems such as chromatographic drifts and peak overlap. In this paper, we propose a Tchebichef moment method for the simultaneous quantitative analysis of three active compounds in Qingrejiedu oral liquid based on three-dimensional spectra in full scan mode of liquid chromatography with mass spectrometry. After the Tchebichef moments were calculated directly from the spectra, the quantitative linear models for three active compounds were established by stepwise regression. All the correlation coefficients were more than 0.9978. The limits of detection and limits of quantitation were less than 0.11 and 0.49 μg/mL, respectively. The intra- and interday precisions were less than 6.54 and 9.47%, while the recovery ranged from 102.56 to 112.15%. Owing to the advantages of multi-resolution and inherent invariance properties, Tchebichef moments could provide favorable results even in the situation of peaks shifting and overlapping, unknown interferences and noise signals, so it could be applied to the analysis of three-dimensional spectra in full scan mode of liquid chromatography with mass spectrometry.
Kelvin waves in ECMWF analysis: normal-mode diagnostics
NASA Astrophysics Data System (ADS)
Blaauw, Marten; Zagar, Nedjeljka
2013-04-01
Equatorial Kelvin waves show a large spread in spatial and temporal variability similar to their source of tropical convective forcing. Once decoupled from their source, Kelvin waves are modulated during their ascent by changes in the background wind and stability. In this presentation, we focus on the seasonal and interannual variability of Kelvin waves in relation with variability of (i) tropical convection and (ii) background zonal wind and static stability. Global data is extracted from ECMWF operational analysis from January 2007 till May 2011 on 91 model levels (top level at 0.01 hPa) and ~ 25 km horizontal resolution. Using three-dimensional orthogonal normal-mode expansions, we project input mass and wind data simultaneously onto balanced rotational modes and unbalanced inertia-gravity modes including Kelvin modes. Next, an inverse transformation of Kelvin modes to physical space is performed under the linearity assumption, allowing a study on the spatial and temporal variability of Kelvin wave zonal wind and temperature. Results show an annual cycle in KW zonal wind in agreement with other studies. Minima resp. maxima in zonal wind amplitudes are found in the Indian ocean resp. Western Pacific and are most pronounced in the tropical tropopause at 150 hPa in January and 100 hPa in July. The annual cycle is enhanced (reduced) through interaction with a descending westerly QBO phase and enhanced (reduced) convective forcing. We also note a gradual eastward shift of KW zonal wind maxima till January 2010 in correspondence with an eastward shift of tropical convection.
Analysis of the power capacity of overmoded slow wave structures
Zhang, Dian; Zhang, Jun; Zhong, Huihuang; Jin, Zhenxing
2013-07-15
As the generated wavelength shortens, overmoded slow wave structures (SWSs) with large diameters are employed in O-type Cerenkov high power microwave (HPM) generators to achieve high power capacity. However, reported experimental results suggest that overmoded slow wave HPM generators working at millimeter wavelength output much lower power than those working at X-band do, despite the fact that the value of D/λ (here, D is the average diameter of SWSs and λ is the generated wavelength) of the former is much larger than that of the latter. In order to understand this, the characteristics of the power capacity of the TM{sub 0n} modes in overmoded SWSs are numerically investigated. Our analysis reveals the following facts. First, the power capacity of higher order TM{sub 0n} modes is apparently larger than that of TM{sub 01} mode. This is quite different from the conclusion got in the foregone report, in which the power capacity of overmoded SWSs is estimated by that of smooth cylindrical waveguides. Second, the rate at which the power capacity of TM{sub 01} mode in overmoded SWSs grows with diameter does not slow down as the TM{sub 01} field transforms from “volume wave” to “surface wave.” Third, once the diameter of overmoded SWSs and the beam voltage are fixed, the power capacity of TM{sub 01} wave drops as periodic length L shortens and the generated frequency rises, although the value of D/λ increases significantly. Therefore, it is necessary to investigate the capability of annular electron beam to interact efficiently with higher order TM{sub 0n} modes in overmoded SWSs if we want to improve the power capacity of overmoded O-type Cerenkov HPM generators working at high frequency.
Computation of rotor aerodynamic loads in forward flight using a full-span free wake analysis
NASA Technical Reports Server (NTRS)
Quackenbush, Todd R.; Bliss, Donald B.; Wachspress, Daniel A.; Boschitsch, Alexander H.; Chua, Kiat
1990-01-01
The development of an advanced computational analysis of unsteady aerodynamic loads on isolated helicopter rotors in forward flight is described. The primary technical focus of the development was the implementation of a freely distorting filamentary wake model composed of curved vortex elements laid out along contours of constant vortex sheet strength in the wake. This model captures the wake generated by the full span of each rotor blade and makes possible a unified treatment of the shed and trailed vorticity in the wake. This wake model was coupled to a modal analysis of the rotor blade dynamics and a vortex lattice treatment of the aerodynamic loads to produce a comprehensive model for rotor performance and air loads in forward flight dubbed RotorCRAFT (Computation of Rotor Aerodynamics in Forward Flight). The technical background on the major components of this analysis are discussed and the correlation of predictions of performance, trim, and unsteady air loads with experimental data from several representative rotor configurations is examined. The primary conclusions of this study are that the RotorCRAFT analysis correlates well with measured loads on a variety of configurations and that application of the full span free wake model is required to capture several important features of the vibratory loading on rotor blades in forward flight.
Gas Analysis by Fourier Transform Mm-Wave Spectroscopy
NASA Astrophysics Data System (ADS)
Harris, Brent J.; Steber, Amanda L.; Lehmann, Kevin K.; Pate, Brooks H.
2013-06-01
Molecular rotational spectroscopy of low pressure, room temperature gases offers high chemical selectivity and sensitivity with the potential for a wide range of applications in gas analysis. A strength of the technique is the potential to identify molecules that have not been previously studied by rotational spectroscopy by comparing experimental results to predictions of the spectroscopic parameters from quantum chemistry -6 so called library-free detection. The development of Fourier transform mm-wave spectrometers using high peak power (30 mW) active multiplier chain mm-wave sources brings new measurement capabilities to the analysis of complex gas mixtures. Strategies for gas analysis based on high-throughput mm-wave spectroscopy and arbitrary waveform generator driven mm-wave sources are described. Several new measurement capabilities come from the intrinsic time-domain measurement technique. High-sensitivity double-resonance measurements can be performed to speed the analysis of a complex gas sample containing several species. This technique uses a "pi-pulse" to selectively invert the population of two selected rotational energy levels and the effect of this excitation pulse on all other transitions in the spectrometer operating range is monitored using segmented chirped-pulse Fourier transform spectroscopy. This method can lead to automated determination of the molecular rotational constants. Rapid pulse duration scan experiments can be used to estimate the magnitude and direction of the dipole moment of the molecule from an unknown spectrum. Coherent pulse echo experiments, using the traditional Hahn sequence or two-color population recovery methods, can be used to determine the collisional relaxation rate of the unknown molecule. This rate determination improves the ability to estimate the mass of the unknown molecule from the determination of the Doppler dephasing rate. By performing a suite of automated, high-throughput measurements, there is the
Stability analysis for extended models of gap solitary waves
Schollmann; Mayer
2000-05-01
A numerical linear stability analysis has been carried out for stationary spatially localized solutions of several systems of coupled nonlinear partial differential equations (PDE's) with two and more complex variables. These coupled PDE's have recently been discussed in the literature, mostly in the context of physical systems with a frequency gap in the dispersion relation of their linear excitations, and they are extensions of the Mills-Trullinger gap soliton model. Translational and oscillatory instabilities are identified, and their associated growth rates are computed as functions of certain parameters characterizing the solitary waves.
Rigorous coupled-wave analysis for two-dimensional gratings
NASA Astrophysics Data System (ADS)
Logofătu, Petre Cătălin
2005-08-01
Rigorous Coupled-Wave Analysis for 2D gratings is reviewed. The main features of RCWA such as the Fourier expansion of the dielectric function in the grating area, solving the Maxwell equation inside the grating, the eigenvalue problem and the matching of the tangential fields at the interfaces are described. Key improvements of the theory, that allows the reduction of the work time by orders of magnitude, such as the reduction of the sue of the matrix for the eigenvalue problem are stressed. The computer code written based on this theory passed consistency tests and was checked against other computer codes.
Basic gait analysis based on continuous wave radar.
Zhang, Jun
2012-09-01
A gait analysis method based on continuous wave (CW) radar is proposed in this paper. Time-frequency analysis is used to analyze the radar micro-Doppler echo from walking humans, and the relationships between the time-frequency spectrogram and human biological gait are discussed. The methods for extracting the gait parameters from the spectrogram are studied in depth and experiments on more than twenty subjects have been performed to acquire the radar gait data. The gait parameters are calculated and compared. The gait difference between men and women are presented based on the experimental data and extracted features. Gait analysis based on CW radar will provide a new method for clinical diagnosis and therapy.
NASA Astrophysics Data System (ADS)
Mourmeaux, Nicolas; Meunier, Félicien; Tran, Phuong Anh; Draye, Xavier; Lambot, Sébastien
2014-05-01
Root water uptake dynamics at local scale can be studied in laboratory conditions by growing plants in rhizotron containing sand and by imaging the water content evolution of the medium using light transmission. This technique allows to retrieve the water content with high resolution but cannot be applied in opaque media such as leaf-mold or clay, which is a major limitation for more realistic applications. Recently, ground-penetrating radar (GPR) has proven to be one of the most promising techniques for high-resolution digital soil mapping at the field scale. Particularly, by using full-wave inverse modeling of near-field GPR data with a high frequency antenna, the electrical properties of soil and their correlated water content can be reconstructed with a high spatiotemporal resolution. In this study, we applied the approach by using an ultra-wideband frequency-domain radar with a transmitting and receiving horn antenna operating in the frequency range 3-6 GHz for imaging, in near-field conditions, a rhizotron containing sand subject to different water content conditions. Synthetic radar data were also generated to examine the well-posedness of the full-waveform inverse problem at high frequencies. Finally, we compared the water content obtained by GPR and light transmission measurements. The results have shown that the near-field modeled and measured GPR data match very well in the frequency and time domains for both dry and wet sands. In the case of the dry sand, the estimated water content based on GPR and light transmission data was retrieved with small differences. This research shows the potential of the GPR system and near-field full-wave antenna-medium model to accurately estimate the water content of soils with a high spatial resolution. Future studies will focus on the use of GPR to monitor root water uptake dynamics of plants in field conditions. This abstract is of interest for COST Action TU1208.
Analysis of upper mantle structure using wave field continuation of P waves
NASA Technical Reports Server (NTRS)
Walck, M. C.; Clayton, R. W.
1984-01-01
Wave field continuation theory, which allows transformation of the seismic record section data directly into velocity-depth space, is tested for upper mantle analysis using a large array-recorded data set obtained at the 200-station Caltech-USGS Southern California Seismic Network that is representative of the structure beneath the gulf of California. The method's resolution capability is illustrated by the comparison of the slant stacks and downward continuation of both synthetic and data record sections. It is stressed that when high-quality, densely sampled digital data are available, the technique is easy to implement, provides an inversion which contains all the data in the global format, and produces an objective estimate of depth resolution as a function of ray parameter.
NASA Astrophysics Data System (ADS)
Harvey, R. W. (Bob); Petrov, Yu. V.; Jaeger, E. F.; Berry, L. A.; Bonoli, P. T.; Bader, A.
2015-11-01
A time-dependent simulation of C-Mod pulsed ICRF power is made calculating minority hydrogen ion distribution functions with the CQL3D-Hybrid-FOW finite-orbit-width Fokker-Planck code. ICRF fields are calculated with the AORSA full wave code, and RF diffusion coefficients are obtained from these fields using the DC Lorentz gyro-orbit code. Prior results with a zero-banana-width simulation using the CQL3D/AORSA/DC time-cycles showed a pronounced enhancement of the H distribution in the perpendicular velocity direction compared to results obtained from Stix's quasilinear theory, in general agreement with experiment. The present study compares the new FOW results, including relevant gyro-radius effects, to determine the importance of these effects on the the NPA synthetic diagnostic time-dependence. The new NPA results give increased agreement with experiment, particularly in the ramp-down time after the ICRF pulse. Funded, through subcontract with Massachusetts Institute of Technology, by USDOE sponsored SciDAC Center for Simulation of Wave-Plasma Interactions.
Comparative Network Analysis of Preterm vs. Full-Term Infant-Mother Interactions
Kalmár, Magda; Tóth, Ildikó; Krishna, Sandeep; Jensen, Mogens H.; Semsey, Szabolcs
2013-01-01
Several studies have reported that interactions of mothers with preterm infants show differential characteristics compared to that of mothers with full-term infants. Interaction of preterm dyads is often reported as less harmonious. However, observations and explanations concerning the underlying mechanisms are inconsistent. In this work 30 preterm and 42 full-term mother-infant dyads were observed at one year of age. Free play interactions were videotaped and coded using a micro-analytic coding system. The video records were coded at one second resolution and studied by a novel approach using network analysis tools. The advantage of our approach is that it reveals the patterns of behavioral transitions in the interactions. We found that the most frequent behavioral transitions are the same in the two groups. However, we have identified several high and lower frequency transitions which occur significantly more often in the preterm or full-term group. Our analysis also suggests that the variability of behavioral transitions is significantly higher in the preterm group. This higher variability is mostly resulted from the diversity of transitions involving non-harmonious behaviors. We have identified a maladaptive pattern in the maternal behavior in the preterm group, involving intrusiveness and disengagement. Application of the approach reported in this paper to longitudinal data could elucidate whether these maladaptive maternal behavioral changes place the infant at risk for later emotional, cognitive and behavioral disturbance. PMID:23805298
Wave-front analysis using Fresnel lens arrays.
Spektor, B; Shamir, J
1995-07-01
A compact wave-front sensor is implemented by an array of two-beam common path inversion interferometers. Each element of the array consists of two Fresnel lenses in a confocal configuration. The wave-front data can be extracted from a superposition of the zero-order undiffracted wave and the twice-diffracted first-order wave. The result is a high-sensitivity, compact, and stable interferometric wave-front sensor.
Third generation sfermion decays into Z and W gauge bosons: Full one-loop analysis
Arhrib, Abdesslam; Benbrik, Rachid
2005-05-01
The complete one-loop radiative corrections to third-generation scalar fermions into gauge bosons Z and W{sup {+-}} is considered. We focus on f-tilde{sub 2}{yields}Zf-tilde{sub 1} and f-tilde{sub i}{yields}W{sup {+-}}f-tilde{sub j}{sup '}, f,f{sup '}=t,b. We include SUSY-QCD, QED, and full electroweak corrections. It is found that the electroweak corrections can be of the same order as the SUSY-QCD corrections. The two sets of corrections interfere destructively in some region of parameter space. The full one-loop correction can reach 10% in some supergravity scenario, while in model independent analysis like general the minimal supersymmetric standard model, the one-loop correction can reach 20% for large tan{beta} and large trilinear soft breaking terms A{sub b}.
Full-Band Monte Carlo Analysis of Hot-Carrier Light Emission in GaAs
NASA Astrophysics Data System (ADS)
Ferretti, I.; Abramo, A.; Brunetti, R.; Jacobini, C.
1997-11-01
A computational analysis of light emission from hot carriers in GaAs due to direct intraband conduction-conduction (c-c) transitions is presented. The emission rates have been evaluated by means of a Full-Band Monte-Carlo simulator (FBMC). Results have been obtained for the emission rate as a function of the photon energy, for the emitted and absorbed light polarization along and perpendicular to the electric field direction. Comparison has been made with available experimental data in MESFETs.
Full-Length High-Temperature Severe Fuel Damage Test No. 5: Final safety analysis
Lanning, D.D.; Lombardo, N.J.; Panisko, F.E.
1993-09-01
This report presents the final safety analysis for the preparation, conduct, and post-test discharge operation for the Full-Length High Temperature Experiment-5 (FLHT-5) to be conducted in the L-24 position of the National Research Universal (NRU) Reactor at Chalk River Nuclear Laboratories (CRNL), Ontario, Canada. The test is sponsored by an international group organized by the US Nuclear Regulatory Commission. The test is designed and conducted by staff from Pacific Northwest Laboratory with CRNL staff support. The test will study the consequences of loss-of-coolant and the progression of severe fuel damage.
Analysis of the 237Np-233Pa photon spectrum using the full response function method.
Shchukin, G; Iakovlev, K; Morel, J
2004-01-01
A study has been made of X- and gamma-ray emission from 237Np in equilibrium with 233Pa using the full response function method. This analysis process is characterised by photon spectrometry in which the entire spectrum is modelled in a pseudo-empirical way by means of elementary functions describing the total absorption and escape peaks, the Compton diffusion internal and external to the detector and the peaks resulting from detection of internal conversion electrons. This method has been applied to determine the L X-, K X- and gamma-rays emission probabilities in 237Np and 233Pa decay studies.
Rolandi, M Cristina; De Silva, Kalpa; Lumley, Matthew; Lockie, Timothy P E; Clapp, Brian; Spaan, Jos A E; Perera, Divaka; Siebes, Maria
2014-03-01
Wave intensity analysis and wave separation are powerful tools for interrogating coronary, myocardial and microvascular physiology. Wave speed is integral to these calculations and is usually estimated by the single-point technique (SPc), a feasible but as yet unvalidated approach in coronary vessels. We aimed to directly measure wave speed in human coronary arteries and assess the impact of adenosine and nitrate administration. In 14 patients, the transit time Δt between two pressure signals was measured in angiographically normal coronary arteries using a microcatheter equipped with two high-fidelity pressure sensors located Δs = 5 cm apart. Simultaneously, intracoronary pressure and flow velocity were measured with a dual-sensor wire to derive SPc. Actual wave speed was calculated as DNc = Δs/Δt. Hemodynamic signals were recorded at baseline and during adenosine-induced hyperemia, before and after nitroglycerin administration. The energy of separated wave intensity components was assessed using SPc and DNc. At baseline, DNc equaled SPc (15.9 ± 1.8 vs. 16.6 ± 1.5 m/s). Adenosine-induced hyperemia lowered SPc by 40 % (p < 0.005), while DNc remained unchanged, leading to marked differences in respective separated wave energies. Nitroglycerin did not affect DNc, whereas SPc transiently fell to 12.0 ± 1.2 m/s (p < 0.02). Human coronary wave speed is reliably estimated by SPc under resting conditions but not during adenosine-induced vasodilation. Since coronary wave speed is unaffected by microvascular dilation, the SPc estimate at rest can serve as surrogate for separating wave intensity signals obtained during hyperemia, thus greatly extending the scope of WIA to study coronary physiology in humans.
Full-scale experimentations on alternative materials in roads: analysis of study practices.
François, D; Jullien, A; Kerzreho, J P; Chateau, L
2009-03-01
In France beginning in the 1990s, the topic of road construction using various alternative materials has given rise to several studies aimed at clarifying the technical and environmental feasibility of such an option. Although crucial to understanding and forecasting their behaviour in the field, an analysis of feedback from onsite experiences (back analysis) of roads built with alternative materials has not yet been carried out. The aim of the CAREX project (2003-2005) has been to fill this gap at the national scale. Based on a stress-response approach applied to both the alternative material and the road structure and including the description of external factors, a dedicated standardised framework for field data classification and analysis was adopted. To carry out this analysis, a set of 17 documented field experiments was identified through a specific national survey. It appears that a great heterogeneity exists in data processing procedures among studies. The description of material is acceptable while it is generally poor regarding external factors and structure responses. Structure monitoring is usually brief and mechanical loads too weak, which limits the significance of field testing. For future full-scale experiments, strengthening the realism within the testing conditions would be appropriate.
Analysis of Stress Waves Generated in Water Using Ultrashort Laser Pulses
Kim, B.M.; Feit, M.D.; Rubenchik, A.M.; Komashko, A.M.; Reidt, S.; Eichler, J.; Da Silva, L.B.
2000-04-25
A Mach-Zehnder interferometer was used for analysis of pressure waves generated by ultrashort laser pulse ablation of water. It was found that the shock wave generated by plasma formation rapidly decays to an acoustic wave. Both experimental and theoretical studies demonstrated that the energy transfer to the mechanical shock was less than 1%.
NASA Astrophysics Data System (ADS)
Law, Yingyu; Kirkegaard, Rasmus Hansen; Cokro, Angel Anisa; Liu, Xianghui; Arumugam, Krithika; Xie, Chao; Stokholm-Bjerregaard, Mikkel; Drautz-Moses, Daniela I.; Nielsen, Per Halkjær; Wuertz, Stefan; Williams, Rohan B. H.
2016-05-01
Management of phosphorus discharge from human waste is essential for the control of eutrophication in surface waters. Enhanced biological phosphorus removal (EBPR) is a sustainable, efficient way of removing phosphorus from waste water without employing chemical precipitation, but is assumed unachievable in tropical temperatures due to conditions that favour glycogen accumulating organisms (GAOs) over polyphosphate accumulating organisms (PAOs). Here, we show these assumptions are unfounded by studying comparative community dynamics in a full-scale plant following systematic perturbation of operational conditions, which modified community abundance, function and physicochemical state. A statistically significant increase in the relative abundance of the PAO Accumulibacter was associated with improved EBPR activity. GAO relative abundance also increased, challenging the assumption of competition. An Accumulibacter bin-genome was identified from a whole community metagenomic survey, and comparative analysis against extant Accumulibacter genomes suggests a close relationship to Type II. Analysis of the associated metatranscriptome data revealed that genes encoding proteins involved in the tricarboxylic acid cycle and glycolysis pathways were highly expressed, consistent with metabolic modelling results. Our findings show that tropical EBPR is indeed possible, highlight the translational potential of studying competition dynamics in full-scale waste water communities and carry implications for plant design in tropical regions.
A Full Virial Analysis of the Prestellar Cores in the Ophiuchus Molecular Cloud
NASA Astrophysics Data System (ADS)
Pattle, Kate; Ward-Thompson, Derek
We use SCUBA-2, HARP C18O J= 3 -> 2, Herschel and IRAM N2H+ J= 1 -> 0 observations of the Ophiuchus molecular cloud to identify and characterise the properties of the starless cores in the region. The SCUBA-2, HARP and Herschel data were taken as part of the JCMT and Herschel Gould Belt Surveys. We determine masses and temperatures and perform a full virial analysis on our cores, and find that our cores are all either bound or virialised, with gravitational energy and external pressure energy on average of similar importance in confining the cores. There is wide variation from region to region, with cores in the region influenced by B stars (Oph A) being substantially gravitationally bound, and cores in the most quiescent region (Oph C) being pressure-confined. We observe dissipation of turbulence in all our cores, and find that this dissipation is more effective in regions which do not contain outflow-driving protostars. Full details of this analysis are presented by Pattle et al. (2015).
NASA Astrophysics Data System (ADS)
Ceulemans, R.; Janssens, I.; Berhongaray, G.; Broeckx, L.; De Groote, T.; ElKasmioui, O.; Fichot, R.; Njakou Djomo, S.; Verlinden, M.; Zona, D.
2011-12-01
In recent year the environmental impact of fossil fuels and their reduced availability are leading to an increasing interest in renewable energy sources, among them bio-energy. However, the cost/benefit in establishing, managing, and using these plantations for energy production should be quantified together with their environmental impact. In this project we are performing a full life cycle analysis (LCA) balance of the most important greenhouse gases (CO2, CH4, N2O, H2O and O3), together with full energy accounting of a short-rotation coppice (SRC) plantation with fast-growing trees. We established the plantation two years ago and we have been monitoring net fluxes of CO2, N2O, CH4, and O3, in combination with biomass pools (incl. soil) and fluxes, and volatile organic carbon (VOCs). This poplar plantation will be monitored for another two years then harvested and transformed into bio-energy. For the energy accounting we are performing a life cycle analysis and energy efficiency assessments over the entire cycle of the plantation until the production of electricity and heat. Here we present an overview of the results from the first two years from the plantation establishment, and some of the projections based on these first results.
COMPREHENSIVE ANALYSIS OF CORONAL MASS EJECTION MASS AND ENERGY PROPERTIES OVER A FULL SOLAR CYCLE
Vourlidas, A.; Howard, R. A.; Esfandiari, E.; Patsourakos, S.; Yashiro, S.; Michalek, G.
2010-10-20
The LASCO coronagraphs, in continuous operation since 1995, have observed the evolution of the solar corona and coronal mass ejections (CMEs) over a full solar cycle with high-quality images and regular cadence. This is the first time that such a data set becomes available and constitutes a unique resource for the study of CMEs. In this paper, we present a comprehensive investigation of the solar cycle dependence on the CME mass and energy over a full solar cycle (1996-2009) including the first in-depth discussion of the mass and energy analysis methods and their associated errors. Our analysis provides several results worthy of further studies. It demonstrates the possible existence of two event classes: 'normal' CMEs reaching constant mass for >10 R{sub sun} and {sup p}seudo{sup -}CMEs which disappear in the C3 field of view. It shows that the mass and energy properties of CME reach constant levels and therefore should be measured only above {approx}10 R{sub sun}. The mass density (g/R {sup 2}{sub sun}) of CMEs varies relatively little (< order of magnitude) suggesting that the majority of the mass originates from a small range in coronal heights. We find a sudden reduction in the CME mass in mid-2003 which may be related to a change in the electron content of the large-scale corona and we uncover the presence of a 6 month periodicity in the ejected mass from 2003 onward.
Law, Yingyu; Kirkegaard, Rasmus Hansen; Cokro, Angel Anisa; Liu, Xianghui; Arumugam, Krithika; Xie, Chao; Stokholm-Bjerregaard, Mikkel; Drautz-Moses, Daniela I.; Nielsen, Per Halkjær; Wuertz, Stefan; Williams, Rohan B. H.
2016-01-01
Management of phosphorus discharge from human waste is essential for the control of eutrophication in surface waters. Enhanced biological phosphorus removal (EBPR) is a sustainable, efficient way of removing phosphorus from waste water without employing chemical precipitation, but is assumed unachievable in tropical temperatures due to conditions that favour glycogen accumulating organisms (GAOs) over polyphosphate accumulating organisms (PAOs). Here, we show these assumptions are unfounded by studying comparative community dynamics in a full-scale plant following systematic perturbation of operational conditions, which modified community abundance, function and physicochemical state. A statistically significant increase in the relative abundance of the PAO Accumulibacter was associated with improved EBPR activity. GAO relative abundance also increased, challenging the assumption of competition. An Accumulibacter bin-genome was identified from a whole community metagenomic survey, and comparative analysis against extant Accumulibacter genomes suggests a close relationship to Type II. Analysis of the associated metatranscriptome data revealed that genes encoding proteins involved in the tricarboxylic acid cycle and glycolysis pathways were highly expressed, consistent with metabolic modelling results. Our findings show that tropical EBPR is indeed possible, highlight the translational potential of studying competition dynamics in full-scale waste water communities and carry implications for plant design in tropical regions. PMID:27193869
Law, Yingyu; Kirkegaard, Rasmus Hansen; Cokro, Angel Anisa; Liu, Xianghui; Arumugam, Krithika; Xie, Chao; Stokholm-Bjerregaard, Mikkel; Drautz-Moses, Daniela I; Nielsen, Per Halkjær; Wuertz, Stefan; Williams, Rohan B H
2016-05-19
Management of phosphorus discharge from human waste is essential for the control of eutrophication in surface waters. Enhanced biological phosphorus removal (EBPR) is a sustainable, efficient way of removing phosphorus from waste water without employing chemical precipitation, but is assumed unachievable in tropical temperatures due to conditions that favour glycogen accumulating organisms (GAOs) over polyphosphate accumulating organisms (PAOs). Here, we show these assumptions are unfounded by studying comparative community dynamics in a full-scale plant following systematic perturbation of operational conditions, which modified community abundance, function and physicochemical state. A statistically significant increase in the relative abundance of the PAO Accumulibacter was associated with improved EBPR activity. GAO relative abundance also increased, challenging the assumption of competition. An Accumulibacter bin-genome was identified from a whole community metagenomic survey, and comparative analysis against extant Accumulibacter genomes suggests a close relationship to Type II. Analysis of the associated metatranscriptome data revealed that genes encoding proteins involved in the tricarboxylic acid cycle and glycolysis pathways were highly expressed, consistent with metabolic modelling results. Our findings show that tropical EBPR is indeed possible, highlight the translational potential of studying competition dynamics in full-scale waste water communities and carry implications for plant design in tropical regions.
Energy distribution in shallow water ship wakes from a spectral analysis of the wave field
NASA Astrophysics Data System (ADS)
Caplier, Clément; Rousseaux, Germain; Calluaud, Damien; David, Laurent
2016-10-01
This work presents an experimental study of the effects of finite water depth on the waves generated by a ship in a towing tank. The wakes of two hull forms representative of maritime and river ships are measured for both deep water and shallow water configurations and for several Froude numbers. The free surface deformations are measured with an optical stereo-correlation measurement method to access a full and detailed reconstruction of the wave fields. The spatial resolution of the reconstructed wakes allows us to perform a spectral analysis of the waves generated by the ships and to decompose them into a near-field hydrodynamic response and a far-field undulatory component. First, the spectral analysis method is presented and the effects of finite water depth on a theoretical point of view are studied. The analysis of subcritical, trans-critical, and supercritical ship wakes in both real space and spectral space highlights the effects of the finite water depth, of the ship speed, and of the hull shape on the energy distribution in the ship wakes through these different regimes.
Technical Data to Justify Full Burnup Credit in Criticality Safety Licensing Analysis
Enercon Services, Inc.
2011-03-14
ENERCON's understanding of the difficult issues related to obtaining and analyzing additional cross section test data to support Full Burnup Credit. A PIRT (Phenomena Identification and Ranking Table) analysis was performed by ENERCON to evaluate the costs and benefits of acquiring different types of nuclear data in support of Full Burnup Credit. A PIRT exercise is a formal expert elicitation process with the final output being the ranking tables. The PIRT analysis (Table 7-4: Results of PIRT Evaluation) showed that the acquisition of additional Actinide-Only experimental data, although beneficial, was associated with high cost and is not necessarily needed. The conclusion was that the existing Radiochemical Assay (RCA) data plus the French Haut Taux de Combustion (HTC)2 and handbook Laboratory Critical Experiment (LCE) data provide adequate benchmark validation for Actinide-Only Burnup Credit. The PIRT analysis indicated that the costs and schedule to obtain sufficient additional experimental data to support the addition of 16 fission products to Actinide-Only Burnup Credit to produce Full Burnup Credit are quite substantial. ENERCON estimates the cost to be $50M to $100M with a schedule of five or more years. The PIRT analysis highlights another option for fission product burnup credit, which is the application of computer-based uncertainty analyses (S/U - Sensitivity/Uncertainty methodologies), confirmed by the limited experimental data that is already available. S/U analyses essentially transform cross section uncertainty information contained in the cross section libraries into a reactivity bias and uncertainty. Recent work by ORNL and EPRI has shown that a methodology to support Full Burnup Credit is possible using a combination of traditional RCA and LCE validation plus S/U validation for fission product isotopics and cross sections. Further, the most recent cross section data (ENDF/B-VII) can be incorporated into the burnup credit codes at a reasonable cost
An Analysis of Model Scale Data Transformation to Full Scale Flight Using Chevron Nozzles
NASA Technical Reports Server (NTRS)
Brown, Clifford; Bridges, James
2003-01-01
Ground-based model scale aeroacoustic data is frequently used to predict the results of flight tests while saving time and money. The value of a model scale test is therefore dependent on how well the data can be transformed to the full scale conditions. In the spring of 2000, a model scale test was conducted to prove the value of chevron nozzles as a noise reduction device for turbojet applications. The chevron nozzle reduced noise by 2 EPNdB at an engine pressure ratio of 2.3 compared to that of the standard conic nozzle. This result led to a full scale flyover test in the spring of 2001 to verify these results. The flyover test confirmed the 2 EPNdB reduction predicted by the model scale test one year earlier. However, further analysis of the data revealed that the spectra and directivity, both on an OASPL and PNL basis, do not agree in either shape or absolute level. This paper explores these differences in an effort to improve the data transformation from model scale to full scale.
Theoretical analysis of a Love wave biosensor in liquid with a viscoelastic wave guiding layer
NASA Astrophysics Data System (ADS)
Wu, Huiyan; Xiong, Xiangming; Zu, Hongfei; Wang, James H.-C.; Wang, Qing-Ming
2017-02-01
The Love mode surface acoustic wave biosensor is considered as one of the most promising probing methods in biomedical research and diagnosis, which has been applied to detect the mechano-biological behaviors of cells attached to the surface of the device. Recent studies have reported the structural and functional optimization of Love wave biosensors for reducing propagation loss and improving sensitivity; however, the relevant device performance needs to be analyzed in depth in terms of device structure, electromechanical properties of piezoelectric crystal substrates, viscoelastic properties of wave guiding layers, and the effect of liquid loading. In this study, a 36° YX-LiTaO3 based Love wave sensor with a parylene-C wave guiding layer is considered as a cell-based biosensor. A theoretical model is proposed to describe the Love wave propagation in the wave guiding layer and penetration in the liquid medium. Decay length δ for the Love wave penetration in liquid is found to be in the order of ˜50 nm, which agrees well with experimental observations. In addition, the effects of the viscoelastic wave guiding layer and liquid medium on the effective electromechanical coupling coefficient K2 of the sensor, the propagation loss PL, and sensor response to mass loading (mass sensitivity) are investigated. The numerical results indicate that the maximum propagation velocity is found at h/λ = 0, where h is the thickness of the wave guiding layer and λ is the wavelength; and the optimal coupling coefficient and mass sensitivity can be obtained at h/λ = 0.045 and h/λ = ˜0.06 in a vacuum or ˜0.058 in water, respectively. For a good combination of these device performance parameters, it is suggested that the optimal wave guiding layer thickness in a Love wave biosensor is at the vicinity of h/λ = ˜0.05 in a vacuum and ˜0.048 in liquid (water).
Analysis of waves in the plasma guided by a periodical vane-type slow wave structure
Wu, T.J.; Kou, C.S.
2005-10-01
In this study, the dispersion relation has been derived to characterize the propagation of the waves in the plasma guided by a periodical vane-type slow wave structure. The plasma is confined by a quartz plate. Results indicate that there are two different waves in this structure. One is the plasma mode that originates from the plasma surface wave propagating along the interface between the plasma and the quartz plate, and the other is the guide mode that originally travels along the vane-type slow wave structure. In contrast to its original slow wave characteristics, the guide mode becomes a fast wave in the low-frequency portion of the passband, and there exists a cut-off frequency for the guide mode. The vane-type guiding structure has been shown to limit the upper frequency of the passband of the plasma mode, compared with that of the plasma surface wave. In addition, the passband of the plasma mode increases with the plasma density while it becomes narrower for the guide mode. The influences of the parameters of the guiding structure and plasma density on the propagation of waves are also presented.
NASA Astrophysics Data System (ADS)
Wang, Chen; Zhou, Chen; Zhao, Zheng-Yu; Yang, Xu-Bo
2015-08-01
For the study of the various non-linear effects generated in ionospheric modulation experiments, accurate calculation of the field intensity variation in the whole reflection region for an electromagnetic wave vertically impinging upon the ionosphere is meaningful. In this paper, mathematical expressions of the electric field components of the characteristic heating waves are derived, by coupling the equation describing a wave initially impinging vertically upon the ionosphere with the Forsterling equation. The variation of each component of the electric field and the total electric field intensity of the standing wave pattern under a specific density profile are calculated by means of a uniform approximation, which is applied throughout the region near the reflection point. The numerical calculation results demonstrate that the total electric field intensity of the ordinary (O)-mode wave varies rapidly in space and reaches several maxima below the reflection point. Evident swelling phenomena of the electric field intensity are found. Our results also indicate that this effect is more pronounced at higher latitudes and that the geomagnetic field is important for wave pattern variation. The electric field intensity of the standing wave pattern of the extraordinary (X)-mode wave exhibits some growth below the reflection point, but its swelling effect is significantly weaker than that of the O-mode wave.
PREFACE: 14th Gravitational Waves Data Analysis Workshop
NASA Astrophysics Data System (ADS)
Ricci, Fulvio
2010-04-01
The 14th Gravitational Wave Data Analysis Workshop (GWDAW-14) is the last of a long series of annual meetings dedicated to the GW data analysis. This time the workshop was held at the Department of Physics of the University of Rome "Sapienza" and its scientic focus was on strengthening the connection among the gravitational wave and other astrophysical communities. Thus, a significant fraction of the workshop was dedicated to explore the potentialities of the multimessanger astronomy and in particular on the emerging neutrino observatories in conjunction with the GW observations. Moreover, several contributions were devoted to technical details of the analysis of real data from interferometric detectors, aimed at the improvement of the data quality for increasing the confidence in the detection of the first GW event. On the base of these techniques new GW upper limits on the strength of continuous signals from neutron stars and on stochastic background as the event rates of burst and inspiral signals have been set. As chairman of this workshop, I would like to thank the members of the organizing and scientic committees and all the participants which have been the crucial actors of the workshop success. Some of the talks presented during the conference appear in the special issue of Classical and Quantum Gravity, while remaining talks from the symposium are published in this companion volume of Journal of Physics: Conference Series. The ensemble of all these contributions represents the most up-to-date papers on the topics covered by the meeting and, it provides valuable details about current work. Finally , I would also like to thank the institutions and the sponsor that made this meeting possible: University of Rome La Sapienza Italian National Institute of Nuclear Physics - INFN Italian National Institute of Astrophyiscs - INAF University of Rome Tor Vergata University of Sannio E4-Computing Engineering s.p.a. Fulvio Ricci University of La Sapienza and INFN
Multichannel Analysis of Surface Waves and Dam Safety
NASA Astrophysics Data System (ADS)
Karastathis, V. K.
2012-12-01
Geophysical methodologies and particularly the Multichannel Analysis of Surface Waves (MASW) effectively proved their efficiency in the non-destructive testing of the dams, in the last decade, after many successful applications worldwide. The MASW method developed in the outset of this decade considerably improved the prospects and the validity of these geophysical applications. Since MASW and the other geophysical techniques do not require drilling they progressively increased their popularity significantly. The Multichannel Analysis of Surface Waves can be applied for the assessment of both earthen and concrete dams. Nevertheless, mostly cases of earthen dams can be found in the literature. The method can detect and map low shear wave velocity areas potentially associated with low cohesion zones due to differential settlement events in the core or increased seepage. The advantage of MASW is that it is not influenced by the water saturation of the interior of the dam contrary to other methods eg. p-wave tomography. Usually, a joint application of MASW with the p-wave techniques can be an optimal choice since the two methodologies can act complementary. An application of MASW on a three-dimensional structure, such as a dam, however, can actually be considered as a complicated problem since the effects of the lateral structural anomalies can strongly affect the results. For example, in an earthen dam the investigation of the core can be influenced by the presence of the shells. Therefore, the problem should be carefully examined by modeling all these the lateral anomalies with the aim to avoid a misinterpretation of the results. The effectiveness of MASW to the dam safety assessment is presented through two example applications, one at the Mornos Dam, an earthen dam responsible for the water supply of Athens, and a second one at the Marathon Dam which is a concrete dam also used for the water supply of Athens. In the case of Mornos Dam, MASW detected areas affected
Adaptive automatic data analysis in full-field fringe-pattern-based optical metrology
NASA Astrophysics Data System (ADS)
Trusiak, Maciej; Patorski, Krzysztof; Sluzewski, Lukasz; Pokorski, Krzysztof; Sunderland, Zofia
2016-12-01
Fringe pattern processing and analysis is an important task of full-field optical measurement techniques like interferometry, digital holography, structural illumination and moiré. In this contribution we present several adaptive automatic data analysis solutions based on the notion of Hilbert-Huang transform for measurand retrieval via fringe pattern phase and amplitude demodulation. The Hilbert-Huang transform consists of 2D empirical mode decomposition algorithm and Hilbert spiral transform analysis. Empirical mode decomposition adaptively dissects a meaningful number of same-scale subimages from the analyzed pattern - it is a data-driven method. Appropriately managing this set of unique subimages results in a very powerful fringe pre-filtering tool. Phase/amplitude demodulation is performed using Hilbert spiral transform aided by the local fringe orientation estimator. We describe several optical measurement techniques for technical and biological objects characterization basing on the especially tailored Hilbert-Huang algorithm modifications for fringe pattern denoising, detrending and amplitude/phase demodulation.
IMPLODING IGNITION WAVES. I. ONE-DIMENSIONAL ANALYSIS
Kushnir, Doron; Waxman, Eli; Livne, Eli
2012-06-20
We show that converging spherical and cylindrical shock waves may ignite a detonation wave in a combustible medium, provided the radius at which the shocks become strong exceeds a critical radius, R{sub crit}. An approximate analytic expression for R{sub crit} is derived for an ideal gas equation of state and a simple (power-law-Arrhenius) reaction law, and shown to reproduce the results of numerical solutions. For typical acetylene-air experiments we find R{sub crit} {approx} 100 {mu}m (spherical) and R{sub crit} {approx} 1 mm (cylindrical). We suggest that the deflagration to detonation transition (DDT) observed in these systems may be due to converging shocks produced by the turbulent deflagration flow, which reaches sub- (but near) sonic velocities on scales >>R{sub crit}. Our suggested mechanism differs from that proposed by Zel'dovich et al., in which a fine-tuned spatial gradient in the chemical induction time is required to be maintained within the turbulent deflagration flow. Our analysis may be readily extended to more complicated equations of state and reaction laws. An order of magnitude estimate of R{sub crit} within a white dwarf at the pre-detonation conditions believed to lead to Type Ia supernova explosions is 0.1 km, suggesting that our proposed mechanism may be relevant for DDT initiation in these systems. The relevance of our proposed ignition mechanism to DDT initiation may be tested by both experiments and numerical simulations.
Constraint likelihood analysis for a network of gravitational wave detectors
Klimenko, S.; Rakhmanov, M.; Mitselmakher, G.; Mohanty, S.
2005-12-15
We propose a coherent method for detection and reconstruction of gravitational wave signals with a network of interferometric detectors. The method is derived by using the likelihood ratio functional for unknown signal waveforms. In the likelihood analysis, the global maximum of the likelihood ratio over the space of waveforms is used as the detection statistic. We identify a problem with this approach. In the case of an aligned pair of detectors, the detection statistic depends on the cross correlation between the detectors as expected, but this dependence disappears even for infinitesimally small misalignments. We solve the problem by applying constraints on the likelihood functional and obtain a new class of statistics. The resulting method can be applied to data from a network consisting of any number of detectors with arbitrary detector orientations. The method allows us reconstruction of the source coordinates and the waveforms of two polarization components of a gravitational wave. We study the performance of the method with numerical simulations and find the reconstruction of the source coordinates to be more accurate than in the standard likelihood method.
Imploding Ignition Waves. I. One-dimensional Analysis
NASA Astrophysics Data System (ADS)
Kushnir, Doron; Livne, Eli; Waxman, Eli
2012-06-01
We show that converging spherical and cylindrical shock waves may ignite a detonation wave in a combustible medium, provided the radius at which the shocks become strong exceeds a critical radius, R crit. An approximate analytic expression for R crit is derived for an ideal gas equation of state and a simple (power-law-Arrhenius) reaction law, and shown to reproduce the results of numerical solutions. For typical acetylene-air experiments we find R crit ~ 100 μm (spherical) and R crit ~ 1 mm (cylindrical). We suggest that the deflagration to detonation transition (DDT) observed in these systems may be due to converging shocks produced by the turbulent deflagration flow, which reaches sub- (but near) sonic velocities on scales GtR crit. Our suggested mechanism differs from that proposed by Zel'dovich et al., in which a fine-tuned spatial gradient in the chemical induction time is required to be maintained within the turbulent deflagration flow. Our analysis may be readily extended to more complicated equations of state and reaction laws. An order of magnitude estimate of R crit within a white dwarf at the pre-detonation conditions believed to lead to Type Ia supernova explosions is 0.1 km, suggesting that our proposed mechanism may be relevant for DDT initiation in these systems. The relevance of our proposed ignition mechanism to DDT initiation may be tested by both experiments and numerical simulations.
A Rayleigh Wave Analysis at the DESERT Broadband Array
NASA Astrophysics Data System (ADS)
Laske, G.; Desert Team
2003-12-01
A variety of geophysical experiments conducted in the 2000/2001 DESERT project in Israel, Palestine and Jordan provided a rich palette of datasets to examine the crust and uppermost mantle beneath one of Earth's most prominent fault systems, the Dead Sea Transform system (DST). As part of the passive seismic component, thirty broad--band sensors were deployed across the DST for roughly one year. During this deployment we recorded 115 teleseismic earthquakes that are suitable for a fundamental mode surface wave analysis at intermediate periods (20-120s). Analyzing arrival angle measurements we are able to determine the orientation of the horizontal components to within one degree. Some sensors were misaligned by nearly 10 degrees which is confirmed by the station operators (e.g. one station was oriented parallel to a road because the compass broke). The frequency--dependent Rayleigh wave phase at each station is measured with respect to each other rather than relative to a synthetic. This results in a much more precise dataset than what is common for global dispersion datasets. A preliminary analysis reveals a seismically fast but thin lid (about 80~km) to the west of the DST. Toward the east, shallow seismic velocities are low while a deeper low velocity zone is not detected. This contradicts the currently favored thermo-mechanical model for the DST that predicts lithospheric thinning toward the east. Unfortunately, the distribution of sensors at the array was not ideal for a surface wave analysis. The stations west of the DST were equipped with true broad-band sensors (Streckeisen STS-2 or Guralp CMT-3T), while the stations east of the DST were equipped with ''wideband'' Guralp-40T that are considerably noisy at periods longer than 40s. We we able to measure dispersion down to 80~s, sometimes below that, depending on the size of the earthquake, but not for all earthquakes. Dispersion at these periods are needed to trace the bottom of the lithosphere. The apparent
ANALYSIS OF A GLOBAL MORETON WAVE OBSERVED ON 2003 OCTOBER 28
Muhr, N.; Temmer, M.; Veronig, A. M.; Vrsnak, B.; Magdalenic, J. E-mail: mat@igam.uni-graz.a E-mail: bvrsnak@gmail.co
2010-01-10
We study the well-pronounced Moreton wave that occurred in association with the X17.2 flare/CME event of 2003 October 28. This Moreton wave is striking for its global propagation and two separate wave centers, which implies that two waves were launched simultaneously. The mean velocity of the Moreton wave, tracked within different sectors of propagation direction, lies in the range of v approx 900-1100 km s{sup -1} with two sectors showing wave deceleration. The perturbation profile analysis of the wave indicates amplitude growth followed by amplitude weakening and broadening of the perturbation profile, which is consistent with a disturbance first driven and then evolving into a freely propagating wave. The Extreme-Ultraviolet Imaging Telescope wave front is found to lie on the same kinematical curve as the Moreton wave fronts indicating that both are different signatures of the same physical process. Bipolar coronal dimmings are observed on the same opposite east-west edges of the active region as the Moreton wave ignition centers. The radio type II source, which is cospatially located with the first wave front, indicates that the wave was launched from an extended source region (approx>60 Mm). These findings suggest that the Moreton wave is initiated by the coronal mass ejection expanding flanks.
Chao, Pei-Yu; Li, Pai-Chi
2016-08-22
The high imaging resolution and motion sensitivity of optical-based shear wave detection has made it an attractive technique in biomechanics studies with potential for improving the capabilities of shear wave elasticity imaging. In this study we implemented laser speckle contrast imaging for two-dimensional (X-Z) tracking of transient shear wave propagation in agarose phantoms. The mechanical disturbances induced by the propagation of the shear wave caused temporal and spatial fluctuations in the local speckle pattern, which manifested as local blurring. By mechanically moving the sample in the third dimension (Y), and performing two-dimensional shear wave imaging at every scan position, the three-dimensional shear wave velocity distribution of the phantom could be reconstructed. Based on comparisons with the reference shear wave velocity measurements obtained using a commercial ultrasound shear wave imaging system, the developed system can estimate the shear wave velocity with an error of less than 6% for homogeneous phantoms with shear moduli ranging from 1.52 kPa to 7.99 kPa. The imaging sensitivity of our system makes it capable of measuring small variations in shear modulus; the estimated standard deviation of the shear modulus was found to be less than 0.07 kPa. A submillimeter spatial resolution for three-dimensional shear wave imaging has been achieved, as demonstrated by the ability to detect a 1-mm-thick stiff plate embedded inside heterogeneous agarose phantoms.
Dispelling Illusions of Reflection: A New Analysis of the 2007 May 19 Coronal "Wave" Event
NASA Astrophysics Data System (ADS)
Attrill, Gemma D. R.
2010-07-01
A new analysis of the 2007 May 19 coronal wave-coronal mass ejection-dimmings event is offered employing base difference extreme-ultraviolet (EUV) images. Previous work analyzing the coronal wave associated with this event concluded strongly in favor of purely an MHD wave interpretation for the expanding bright front. This conclusion was based to a significant extent on the identification of multiple reflections of the coronal wave front. The analysis presented here shows that the previously identified "reflections" are actually optical illusions and result from a misinterpretation of the running difference EUV data. The results of this new multiwavelength analysis indicate that two coronal wave fronts actually developed during the eruption. This new analysis has implications for our understanding of diffuse coronal waves and questions the validity of the analysis and conclusions reached in previous studies.
DISPELLING ILLUSIONS OF REFLECTION: A NEW ANALYSIS OF THE 2007 MAY 19 CORONAL 'WAVE' EVENT
Attrill, Gemma D. R.
2010-07-20
A new analysis of the 2007 May 19 coronal wave-coronal mass ejection-dimmings event is offered employing base difference extreme-ultraviolet (EUV) images. Previous work analyzing the coronal wave associated with this event concluded strongly in favor of purely an MHD wave interpretation for the expanding bright front. This conclusion was based to a significant extent on the identification of multiple reflections of the coronal wave front. The analysis presented here shows that the previously identified 'reflections' are actually optical illusions and result from a misinterpretation of the running difference EUV data. The results of this new multiwavelength analysis indicate that two coronal wave fronts actually developed during the eruption. This new analysis has implications for our understanding of diffuse coronal waves and questions the validity of the analysis and conclusions reached in previous studies.
2016-06-07
Study Of Ocean Bottom Interactions With Acoustic Waves By A New Elastic Wave Propagation Algorithm And An Energy Flow Analysis Technique Ru-Shan Wu...imaging to study the wave/sea-bottom interaction, energy partitioning, scattering mechanism and other problems that are crucial for many ocean bottom...Elastic Wave Propagation Algorithm And An Energy Flow Analysis Technique 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR
Peer Support in Full-Service Partnerships: A Multiple Case Study Analysis.
Siantz, Elizabeth; Henwood, Benjamin; Gilmer, Todd
2017-02-11
Peer providers are integral to Full Service Partnerships (FSPs), which are team-based mental health service models. Peer providers use principles of recovery to engage clients, but FSPs can vary in their recovery orientation. Whether and how peer recovery orientation reflects the organizational environments of FSPs is unclear. This qualitative study explored peer provider attitudes towards recovery within the organizational contexts of FSPs where they are employed. Case study analysis was conducted on eight purposively sampled FSPs using qualitative interviews with peer providers and program directors. In two cases, peer recovery attitudes diverged from those of their organizational context. In these cases, peer providers were champions for recovery, and used practice-based strategies to promote client autonomy despite working in settings with lower recovery orientation. Peer providers could be uniquely positioned to promote client autonomy in settings where organizational factors limit consumer choice.
A new method for COD analysis with full-spectrum based on Artificial Neural Network
NASA Astrophysics Data System (ADS)
Feng, Wei-wei; Li, Dan; Cai, Zong-qi; Hao, Fu-guo
2016-09-01
A new on-line monitoring system was developed for the determination of chemical oxygen demand (COD) in water based on full-spectrum analysis. In this system, Artificial Neural Net (ANN) work was used to obtain the transmission equation between absorbance and COD value by measuring absorption spectra of water with known COD value, and then the established equation could inverse the COD values of the unknown water samples. For the COD determination of simulated complicated water samples, the instrumental reliability was well validated by a comparison made between the ANN method and the PLS method. The monitoring system of the ANN method provided advantages of simplicity, rapidity, high precision, no consumption of reagent. And it was demonstrated an ideal alternative to real-time and on-line monitoring of COD in water.
Fluorogenic boronate-based probe-lactulose complex for full-aqueous analysis of peroxynitrite.
Li, Kai-Bin; Dong, Lei; Zhang, Siqi; Shi, Wei; Jia, Wen-Ping; Han, De-Man
2017-04-01
A selective fluorogenic boronate-based probe-lactulose complex was evaluated for the rapid analysis of peroxynitrite (ONOO(-)) based on a reaction-based indicator displacement assay (RIA). The probe was synthesised by a simple nucleophilic substitution reaction between a boronic acid moiety and a well known laser dye, DCM. Fluorescence analyses showed that the probe had an off-on response to lactulose, forming a fluorogenic probe-lactulose complex. The subsequent addition of ONOO(-) selectively quenched the fluorescence of the complex over other Reactive Oxygen/ Nitrogen Species (ROS/RNS) tested. The complex can be applied for the rapid determination of ONOO(-) in full aqueous solution with good linear range, and has also proven suitable for monitoring ONOO(-) in living cells and real water samples.
Analysis of wear-debris from full-scale bearing fatigue tests using the ferrograph
NASA Technical Reports Server (NTRS)
Jones, W. R.; Loewenthal, S. H.
1980-01-01
The ferrograph was used to determine the types and quantities of wear particles generated during full-scale bearing fatigue tests. Deep-groove ball bearings made from AISI 52100 steel were used. A MIL-L-23699 tetraester lubricant was used in a recirculating lubrication system containing a 49 mm absolute filter. Test conditions included a maximum Hertz stress of 2.4 GPa, a shaft speed of 15,000 rpm, and a lubricant supply temperature of 74 C (165 F). Four fatigue failures were detected by accelerometers in this test set. In general, the ferrograph was more sensitive (up to 23 hr) in detecting spall initiation than either accelerometers or the normal spectrographic oil analysis. Four particle types were observed: normal rubbing wear particles, spheres, nonferrous particles, and severe wear (spall) fragments.
Analysis of wear debris from full-scale bearing fatigue tests using the Ferrograph
NASA Technical Reports Server (NTRS)
Jones, W. R., Jr.; Loewenthal, S. H.
1980-01-01
The Ferrograph was used to determine the types of quantities of wear particles generated during full-scale bearing fatigue tests. Deep-groove ball bearings made from AISI 52100 steel were used. A MIL-L-23699 tetraester lubricant was used in a recirculating lubrication system containing a 49-micron absolute filter. Test conditions included a maximum Hertz stress of 2.4 GPa, a shaft speed of 15,000 rpm and a lubricant supply temperature of 74 C (165 F). Four fatigue failures were detected by accelerometers in this test set. In general, the Ferrograph was more sensitive (up to 23 h) in detecting spall initiation than either accelerometers or the normal spectrographic oil analysis (SOAP). Four particle types were observed: normal rubbing wear particles, spheres, nonferrous particles, and severe wear (spall) fragments.
Video analysis of dust events in full-tungsten ASDEX Upgrade
NASA Astrophysics Data System (ADS)
Brochard, F.; Shalpegin, A.; Bardin, S.; Lunt, T.; Rohde, V.; Briançon, J. L.; Pautasso, G.; Vorpahl, C.; Neu, R.; The ASDEX Upgrade Team
2017-03-01
Fast video data recorded during seven consecutive operation campaigns (2008-2012) in full-tungsten ASDEX Upgrade have been analyzed with an algorithm developed to automatically detect and track dust particles. A total of 2425 discharges have been analyzed, corresponding to 12 204 s of plasma operation. The analysis aimed at precisely identifying and sorting the discharge conditions responsible of the dust generation or remobilization. Dust rates are found to be significantly lower than in tokamaks with carbon PFCs. Significant dust events occur mostly during off-normal plasma phases such as disruptions and particularly those preceded by vertical displacement events (VDEs). Dust rates are also increased but to a lower extent during type-I ELMy H-modes. The influences of disruption energy, heating scenario, vessel venting and vessel vibrations are also presented.
Ferrographic analysis of wear debris from full-scale bearing fatigue tests
NASA Technical Reports Server (NTRS)
Jones, W. R., Jr.; Loewenthal, S. H.
1979-01-01
The Ferrograph was used to determine the types and quantities of wear particles generated during full scale bearing fatigue tests. Deep-groove ball bearings made from steel were used. A tetraester lubricant was used in a recirculating lubricant system containing a 49 micrometers absolute filter. Test conditions include a maximum Hertz stress of 2.4 GPa, a shaft speed of 15,000 rpm, and a lubricant supply temperature of 74 C (165 F). Four fatigue failures were detected by accelerometers in this test set. In general, the Ferrograph was more sensitive (up to 23 hr) in detecting spall initiation than either accelerometers or the normal spectrographic oil analysis. Four particle types were observed: normal rubbing weather particles, spheres, nonferrous particles, and severe wear (spall) fragments.
Full Polarization Analysis of Resonant Superlattice and Forbidden x-ray Reflections in Magnetite
Wilkins, S.B.; Bland, S.R.; Detlefs, B.; Beale, T.A.W.; Mazzoli, C.; Joly, Y.; Hatton, P.D.; Lorenzo, J.E.; Brabers, V.A.M.
2009-12-02
Despite being one of the oldest known magnetic materials, and the classic mixed valence compound, thought to be charge ordered, the structure of magnetite below the Verwey transition is complex and the presence and role of charge order is still being debated. Here, we present resonant x-ray diffraction data at the iron K-edge on forbidden (0, 0, 2n+1){sub C} and superlattice (0, 0, 2n+1/2)C reflections. Full linear polarization analysis of the incident and scattered light was conducted in order to explore the origins of the reflections. Through simulation of the resonant spectra we have confirmed that a degree of charge ordering takes place, while the anisotropic tensor of susceptibility scattering is responsible for the superlattice reflections below the Verwey transition. We also report the surprising result of the conversion of a significant proportion of the scattered light from linear to nonlinear polarization.
Gamma-ray Full Spectrum Analysis for Environmental Radioactivity by HPGe Detector
NASA Astrophysics Data System (ADS)
Jeong, Meeyoung; Lee, Kyeong Beom; Kim, Kyeong Ja; Lee, Min-Kie; Han, Ju-Bong
2014-12-01
Odyssey, one of the NASA¡¯s Mars exploration program and SELENE (Kaguya), a Japanese lunar orbiting spacecraft have a payload of Gamma-Ray Spectrometer (GRS) for analyzing radioactive chemical elements of the atmosphere and the surface. In these days, gamma-ray spectroscopy with a High-Purity Germanium (HPGe) detector has been widely used for the activity measurements of natural radionuclides contained in the soil of the Earth. The energy spectra obtained by the HPGe detectors have been generally analyzed by means of the Window Analysis (WA) method. In this method, activity concentrations are determined by using the net counts of energy window around individual peaks. Meanwhile, an alternative method, the so-called Full Spectrum Analysis (FSA) method uses count numbers not only from full-absorption peaks but from the contributions of Compton scattering due to gamma-rays. Consequently, while it takes a substantial time to obtain a statistically significant result in the WA method, the FSA method requires a much shorter time to reach the same level of the statistical significance. This study shows the validation results of FSA method. We have compared the concentration of radioactivity of 40K, 232Th and 238U in the soil measured by the WA method and the FSA method, respectively. The gamma-ray spectrum of reference materials (RGU and RGTh, KCl) and soil samples were measured by the 120% HPGe detector with cosmic muon veto detector. According to the comparison result of activity concentrations between the FSA and the WA, we could conclude that FSA method is validated against the WA method. This study implies that the FSA method can be used in a harsh measurement environment, such as the gamma-ray measurement in the Moon, in which the level of statistical significance is usually required in a much shorter data acquisition time than the WA method.
A Big Data Analytics Pipeline for the Analysis of TESS Full Frame Images
NASA Astrophysics Data System (ADS)
Wampler-Doty, Matthew; Pierce Doty, John
2015-12-01
We present a novel method for producing a catalogue of extra-solar planets and transients using the full frame image data from TESS. Our method involves (1) creating a fast Monte Carlo simulation of the TESS science instruments, (2) using the simulation to create a labeled dataset consisting of exoplanets with various orbital durations as well as transients (such as tidal disruption events), (3) using supervised machine learning to find optimal matched filters, Support Vector Machines (SVMs) and statistical classifiers (i.e. naïve Bayes and Markov Random Fields) to detect astronomical objects of interest and (4) “Big Data” analysis to produce a catalogue based on the TESS data. We will apply the resulting methods to all stars in the full frame images. We hope that by providing libraries that conform to industry standards of Free Open Source Software we may invite researchers from the astronomical community as well as the wider data-analytics community to contribute to our effort.
Agricultural Land Classification Based on Statistical Analysis of Full Polarimetric SAR Data
NASA Astrophysics Data System (ADS)
Mahdian, M.; Homayouni, S.; Fazel, M. A.; Mohammadimanesh, F.
2013-09-01
The discrimination capability of Polarimetric Synthetic Aperture Radar (PolSAR) data makes them a unique source of information with a significant contribution in tackling problems concerning environmental applications. One of the most important applications of these data is land cover classification of the earth surface. These data type, make more detailed classification of phenomena by using the physical parameters and scattering mechanisms. In this paper, we have proposed a contextual unsupervised classification approach for full PolSAR data, which allows the use of multiple sources of statistical evidence. Expectation-Maximization (EM) classification algorithm is basically performed to estimate land cover classes. The EM algorithm is an iterative algorithm that formalizes the problem of parameters estimation of a mixture distribution. To represent the statistical properties and integrate contextual information of the associated image data in the analysis process we used Markov random field (MRF) modelling technique. This model is developed by formulating the maximum posteriori decision rule as the minimization of suitable energy functions. For select optimum distribution which adapts the data more efficiently we used Mellin transform which is a natural analytical tool to study the distribution of products and quotients of independent random variables. Our proposed classification method is applied to a full polarimetric L-band dataset acquired from an agricultural region in Winnipeg, Canada. We evaluate the classification performance based on kappa and overall accuracies of the proposed approach and compared with other well-known classic methods.
The application of thermoelastic stress analysis to full-scale aerospace structures
NASA Astrophysics Data System (ADS)
Fruehmann, R. K.; Dulieu-Barton, J. M.; Quinn, S.; Peton-Walter, J.; Mousty, P. A. N.
2012-08-01
Non-destructive evaluation (NDE) techniques that can be applied in-situ are particularly relevant to the testing of large scale structures that cannot easily be taken into a laboratory for inspection. The application of established laboratory based techniques to the inspection of such structures therefore brings with it a new set of challenges associated with the change in operating environment between the laboratory and 'the field'. The current work investigates the use of thermoelastic stress analysis (TSA) to inspect carbon fibre composite aerospace components for manufacturing defects and in-service damage. An initial study using single transient loads to obtain a measureable change in temperature that can be related to the change in the sum of the principal stresses showed a good agreement with the traditional methodology. However, for large structures, the energy required to obtain a sufficiently large stress change to obtain a resolvable measurement may require an actuator that is not easily portable. Hence a number of ideas have been proposed to reduce the power requirement and deal with small signal to noise ratios. This paper describes the use of natural frequency vibration modes to enable large stress changes to be generated with minimal power input. Established signal processing in the form of a lock-in amplifier and Fourier signal analysis is applied. Tests on a laboratory scale flat plate and full-scale representative wing skin and stringer specimen are presented.
Baig, Anisullah; Gamzina, Diana; Barchfeld, Robert; Domier, Calvin; Barnett, Larry R.; Luhmann, Neville C. Jr.
2012-09-15
In this paper, we describe micro-fabrication, RF measurements, and particle-in-cell (PIC) simulation modeling analysis of the 0.22 THz double-vane half period staggered traveling wave tube amplifier (TWTA) circuit. The TWTA slow wave structure comprised of two sections separated by two sever ports loaded by loss material, with integrated broadband input/output couplers. The micro-metallic structures were fabricated using nano-CNC milling and diffusion bonded in a three layer process. The 3D optical microscopy and SEM analysis showed that the fabrication error was within 2-3 {mu}m and surface roughness was measured within 30-50 nm. The RF measurements were conducted with an Agilent PNA-X network analyzer employing WR5.1 T/R modules with a frequency range of 178-228 GHz. The in-band insertion loss (S{sub 21}) for both the short section and long section (separated by a sever) was measured as {approx}-5 dB while the return loss was generally around {approx}-15 dB or better. The measurements matched well with the S-matrix simulation analysis that predicted a 3 dB bandwidth of {approx}45 GHz with an operating frequency at 220 GHz. However, the measured S{sub 21} was {approx}3 dB less than the design values, and is attributed to surface roughness and alignment issues. The confirmation measurements were conducted over the full frequency band up to 270 GHz employing a backward wave oscillator (BWO) scalar network analyzer setup employing a BWO in the frequency range 190 GHz-270 GHz. PIC simulations were conducted for the realistic TWT output power performance analysis with incorporation of corner radius of 127 {mu}m, which is inevitably induced by nano-machining. Furthermore, the S{sub 21} value in both sections of the TWT structure was reduced to correspond to the measurements by using a degraded conductivity of 10% International Annealed Copper Standard. At 220 GHz, for an elliptic sheet electron beam of 20 kV and 0.25 A, the average output power of the tube was predicted
NASA Technical Reports Server (NTRS)
Kiedron, K.; Chian, C. T.
1985-01-01
As a check on structure safety aspects, two approaches in seismic analysis for the large 70-m antennas are presented. The first approach, commonly used by civil engineers, utilizes known recommended design response spectra. The second approach, which is the full transient analysis, is versatile and applicable not only to earthquake loading but also to other dynamic forcing functions. The results obtained at the fundamental structural frequency show that the two approaches are in good agreement with each other and both approaches show a safe design. The results also confirm past 64-m antenna seismic studies done by the Caltech Seismology Staff.
Analysis of the Interactions of Planetary Waves with the Mean Flow of the Stratosphere
NASA Technical Reports Server (NTRS)
Newman, Paul A.
2007-01-01
During the winter period, large scale waves (planetary waves) are observed to propagate from the troposphere into the stratosphere. Such wave events have been recognized since the 1 950s. The very largest wave events result in major stratospheric warmings. These large scale wave events have typical durations of a few days to 2 weeks. The wave events deposit easterly momentum in the stratosphere, decelerating the polar night jet and warming the polar region. In this presentation we show the typical characteristics of these events via a compositing analysis. We will show the typical periods and scales of motion and the associated decelerations and warmings. We will illustrate some of the differences between major and minor warming wave events. We will further illustrate the feedback by the mean flow on subsequent wave events.
Image analysis for denoising full-field frequency-domain fluorescence lifetime images.
Spring, B Q; Clegg, R M
2009-08-01
Video-rate fluorescence lifetime-resolved imaging microscopy (FLIM) is a quantitative imaging technique for measuring dynamic processes in biological specimens. FLIM offers valuable information in addition to simple fluorescence intensity imaging; for instance, the fluorescence lifetime is sensitive to the microenvironment of the fluorophore allowing reliable differentiation between concentration differences and dynamic quenching. Homodyne FLIM is a full-field frequency-domain technique for imaging fluorescence lifetimes at every pixel of a fluorescence image simultaneously. If a single modulation frequency is used, video-rate image acquisition is possible. Homodyne FLIM uses a gain-modulated image intensified charge-coupled device (ICCD) detector, which unfortunately is a major contribution to the noise of the measurement. Here we introduce image analysis for denoising homodyne FLIM data. The denoising routine is fast, improves the extraction of the fluorescence lifetime value(s) and increases the sensitivity and fluorescence lifetime resolving power of the FLIM instrument. The spatial resolution (especially the high spatial frequencies not related to noise) of the FLIM image is preserved, because the denoising routine does not blur or smooth the image. By eliminating the random noise known to be specific to photon noise and from the intensifier amplification, the fidelity of the spatial resolution is improved. The polar plot projection, a rapid FLIM analysis method, is used to demonstrate the effectiveness of the denoising routine with exemplary data from both physical and complex biological samples. We also suggest broader impacts of the image analysis for other fluorescence microscopy techniques (e.g. super-resolution imaging).
A selection model for accounting for publication bias in a full network meta-analysis.
Mavridis, Dimitris; Welton, Nicky J; Sutton, Alex; Salanti, Georgia
2014-12-30
Copas and Shi suggested a selection model to explore the potential impact of publication bias via sensitivity analysis based on assumptions for the probability of publication of trials conditional on the precision of their results. Chootrakool et al. extended this model to three-arm trials but did not fully account for the implications of the consistency assumption, and their model is difficult to generalize for complex network structures with more than three treatments. Fitting these selection models within a frequentist setting requires maximization of a complex likelihood function, and identification problems are common. We have previously presented a Bayesian implementation of the selection model when multiple treatments are compared with a common reference treatment. We now present a general model suitable for complex, full network meta-analysis that accounts for consistency when adjusting results for publication bias. We developed a design-by-treatment selection model to describe the mechanism by which studies with different designs (sets of treatments compared in a trial) and precision may be selected for publication. We fit the model in a Bayesian setting because it avoids the numerical problems encountered in the frequentist setting, it is generalizable with respect to the number of treatments and study arms, and it provides a flexible framework for sensitivity analysis using external knowledge. Our model accounts for the additional uncertainty arising from publication bias more successfully compared to the standard Copas model or its previous extensions. We illustrate the methodology using a published triangular network for the failure of vascular graft or arterial patency.
Transient wave propagation analysis of a pantograph- catenary system
NASA Astrophysics Data System (ADS)
Nagao, Kyohei; Masuda, Arata
2016-09-01
This paper proposes a systematic method to analyze the dynamic response of an overhead catenary with pantographs moving at constant speed. The overhead catenary is modeled as a onedimensional infinite-length string, which is periodically supported by hangers. On the other hand, the pantograph is a sub-structure moving at a constant speed, which is modeled as a lumped mass system contacting the catenary. In this study, the whole system is divided into elements in the manner of the transfer matrix method. Then, the relationship among traveling waves in every element is systematically obtained in the Laplace domain following the method of reverberation-ray matrix. Since the governing equation of the system changes periodically with time, the analysis of the temporal evolution of the system can be realized by repeating a single period analysis starting from the instant when the pantograph comes into a unit cell by means of the reverberation-ray matrix analysis followed by the inverse Laplace transform. When the pantograph reaches the opposite hanger, the whole elements are shifted backward, and the catenary response of the forehead element is used as the initial condition of the next period.
Comparative analysis on penetrating depth of high-frequency Rayleigh and Love waves
NASA Astrophysics Data System (ADS)
Yin, Xiaofei; Xia, Jianghai; Shen, Chao; Xu, Hongrui
2014-12-01
A particular mode of surface waves possesses a unique phase velocity for each wavelength. Different wavelengths primarily reflect geological information at different depths. In practice, knowledge on penetrating depth of surface wave data is extremely important to define an earth model for inverting their phase velocities. For a layered model, we use the Jacobian matrix to investigate the relationship between wavelength and penetrating depth. The results show that a different mode of surface waves is sensitive to a different depth range. No matter for Rayleigh or Love waves, higher mode waves can penetrate deeper than fundamental mode waves do. For a normal model (S-wave velocity increases with depth) and given the same wavelength, the fundamental mode Rayleigh-wave data can 'see' 1.3-1.4 times deeper than that of Love waves. In addition, the higher-mode components of the two waves can penetrate the same depth. Our numerical studies based on sensitivity analysis of fundamental mode waves of two kinds of irregular models, HVL (high-velocity-layer model) and LVL (low-velocity-layer model), suggest that both Rayleigh and Love waves are insensitive to the layers beneath an HVL or LVL and the HVL itself. Therefore, wavelengths required for estimating S-wave velocity of these layers are much longer than the normal model.
Irregular Wave Energy Extraction Analysis for a Slider Crank WEC Power Take-Off System
Sang, Yuanrui; Karayaka, H. Bora; Yan, Yanjun; Zhang, James Z.; Muljadi, Eduard
2015-09-02
Slider crank Wave Energy Converter (WEC) is a novel energy conversion device. It converts wave energy into electricity at a relatively high efficiency, and it features a simple structure. Past analysis on this WEC has been done under regular sinusoidal wave conditions, and a suboptimal energy could be achieved. This paper presents the analysis of the system under irregular wave conditions; a time-domain hydrodynamics model is adopted and the control methodology is modified to better serve the irregular wave conditions. Results from the simulations show that the performance of the system under irregular wave conditions is different from that under regular sinusoidal wave conditions, but still a reasonable amount of energy can be extracted.
Dynamic Analysis of the Conditional Oscillator Underlying Slow Waves in Thalamocortical Neurons.
David, François; Crunelli, Vincenzo; Leresche, Nathalie; Lambert, Régis C
2016-01-01
During non-REM sleep the EEG shows characteristics waves that are generated by the dynamic interactions between cortical and thalamic oscillators. In thalamic neurons, low-threshold T-type Ca(2+) channels play a pivotal role in almost every type of neuronal oscillations, including slow (< 1 Hz) waves, sleep spindles and delta waves. The transient opening of T channels gives rise to the low threshold spikes (LTSs), and associated high frequency bursts of action potentials, that are characteristically present during sleep spindles and delta waves, whereas the persistent opening of a small fraction of T channels, (i.e., ITwindow) is responsible for the membrane potential bistability underlying sleep slow oscillations. Surprisingly thalamocortical (TC) neurons express a very high density of T channels that largely exceed the amount required to generate LTSs and therefore, to support certain, if not all, sleep oscillations. Here, to clarify the relationship between T current density and sleep oscillations, we systematically investigated the impact of the T conductance level on the intrinsic rhythmic activities generated in TC neurons, combining in vitro experiments and TC neuron simulation. Using bifurcation analysis, we provide insights into the dynamical processes taking place at the transition between slow and delta oscillations. Our results show that although stable delta oscillations can be evoked with minimal T conductance, the full range of slow oscillation patterns, including groups of delta oscillations separated by Up states ("grouped-delta slow waves") requires a high density of T channels. Moreover, high levels of T conductance ensure the robustness of different types of slow oscillations.
NASA Technical Reports Server (NTRS)
2001-01-01
This document presents the full-scale analyses of the CFD RSRM. The RSRM model was developed with a 20 second burn time. The following are presented as part of the full-scale analyses: (1) RSRM embedded inclusion analysis; (2) RSRM igniter nozzle design analysis; (3) Nozzle Joint 4 erosion anomaly; (4) RSRM full motor port slag accumulation analysis; (5) RSRM motor analysis of two-phase flow in the aft segment/submerged nozzle region; (6) Completion of 3-D Analysis of the hot air nozzle manifold; (7) Bates Motor distributed combustion test case; and (8) Three Dimensional Polysulfide Bump Analysis.
NASA Astrophysics Data System (ADS)
Bluegel, Stefan
2005-03-01
In order to calculate on the basis of the single particle picture as provided by the density-functional theory (DFT), the spin-dependent tunneling through barriers and interfaces of materials with increasing chemical and structural complexity, an extention of the full-potential linearized augmented plane- wave method (FLAPW) as realized in the FLEUR code is introduced. The volume in which the electrons scatter is sandwiched between two semi-infinite leads. The leads and the scattering volume are described by an embedding Green function formalism. Different scenarios of electron transport such as sequential and coherent tunneling is formulated and will be compared. Several applications will be presented. The method is used to understand the spin-polarized scanning tunneling microscope. For a three- layer heterosystem SrRuO3/SrTiO3/SrRuO3, the effect of different orbital characters of the states at the Fermi level on the tunneling conductance was investigated. The main focus is on the Fe/MgO/Fe system for which we show that very small changes at the interface can have drastic effects on the conductance.
Lu, Yunpeng; Lee, Soo-Y; Zhang, Dong H
2006-01-07
A time-dependent initial state selected wave packet method has been developed to study the H2(v(1)=10-11,j1=0)+H2'(v2=0,j2=0)-->HH'+HH' four-center (4C) reaction, and two other competing reactions: the H2+H2'-->H+H+H2' collision induced dissociation (CID) and the H2+H2'-->H+HH'+H' single exchange (SE) reaction, in full six dimensions. Initial state-specific total reaction probabilities for these three competing reactions are presented for total angular momentum J=0 and the effects of reagent vibration on reactions are examined. It is found that (a) the CID process is the dominant process over the whole energy range considered in this study, but the 4C and SE processes also have non-negligible probabilities; (b) the SE process has a lower threshold energy than the 4C process, but the SE probability increases slower than the 4C probability as collision energy increases; (c) the vibrational excitation of H2(v1) is much more efficient than translational motion for promoting these processes, in particular to the CID process.
CORONAL RESPONSE TO AN EUV WAVE FROM DEM ANALYSIS
Vanninathan, K.; Veronig, A. M.; Dissauer, K.; Hannah, I. G.; Kontar, E. P.
2015-10-20
Extreme-Ultraviolet (EUV) waves are globally propagating disturbances that have been observed since the era of the Solar and Heliospheric Observatory/Exteme-ultraviolet Imaging Telescope instrument. Although the kinematics of the wave front and secondary wave components have been widely studied, there is not much known about the generation and plasma properties of the wave. In this paper we discuss the effect of an EUV wave on the local plasma as it passes through the corona. We studied the EUV wave, generated during the 2011 February 15 X-class flare/coronal mass ejection event, using Differential Emission Measure diagnostics. We analyzed regions on the path of the EUV wave and investigated the local density and temperature changes. From our study we have quantitatively confirmed previous results that during wave passage the plasma visible in the Atmospheric Imaging Assembly (AIA) 171 Å channel is getting heated to higher temperatures corresponding to AIA 193 and 211 Å channels. We have calculated an increase of 6%–9% in density and 5%–6% in temperature during the passage of the EUV wave. We have compared the variation in temperature with the adiabatic relationship and have quantitatively demonstrated the phenomenon of heating due to adiabatic compression at the wave front. However, the cooling phase does not follow adiabatic relaxation but shows slow decay indicating slow energy release being triggered by the wave passage. We have also identified that heating is taking place at the front of the wave pulse rather than at the rear. Our results provide support for the case that the event under study here is a compressive fast-mode wave or a shock.
Analysis of spike waves in epilepsy using Hilbert-Huang transform.
Zhu, Jin-De; Lin, Chin-Feng; Chang, Shun-Hsyung; Wang, Jung-Hua; Peng, Tsung-Ii; Chien, Yu-Yi
2015-01-01
In this paper, we used the Hilbert-Huang transform (HHT) analysis method to examine the time-frequency characteristics of spike waves for detecting epilepsy symptoms. We obtained a sample of spike waves and nonspike waves for HHT decomposition by using numerous intrinsic mode functions (IMFs) of the Hilbert transform (HT) to determine the instantaneous, marginal, and Hilbert energy spectra. The Pearson correlation coefficients of the IMFs, and energy-IMF distributions for the electroencephalogram (EEG) signal without spike waves, Spike I, Spike II and Spike III sample waves were determined. The analysis results showed that the ratios of the referred wave and Spike III wave to the referred total energy for IMF1, IMF2, and the residual function exceeded 10%. Furthermore, the energy ratios for IMF1, IMF2, IMF3 and the residual function of Spike I, Spike II to their total energy exceeded 10%. The Pearson correlation coefficients of the IMF3 of the EEG signal without spike waves and Spike I wave, EEG signal without spike waves and Spike II wave, EEG signal without spike waves and Spike III wave, Spike I and II waves, Spike I and III waves, and Spike II and III waves were 0.002, 0.06, 0.01, 0.17, 0.03, and 0.3, respectively. The energy ratios of IMF3 in the δ band to its referred total energy for the EEG signal without spike waves, and of the Spike I, II, and III waves were 4.72, 6.75, 5.41, and 5.55%, respectively. The weighted average frequency of the IMF1, IMF2, and IMF3 of the EEG signal without spike waves was lower than that of the IMF1, IMF2, and IMF3 of the spike waves, respectively. The weighted average magnitude of the IMF3, IMF4, and IMF5 of the EEG signal without spike waves was lower than that of the IMF1, IMF2, and IMF3 of spike waves, respectively.
Analysis of panthers full-scale heat transfer tests with RELAP5
Parlatan, Y.; Boyer, B.D.; Jo, J.; Rohatgi, S.
1996-01-01
The RELAP5 code is being assessed on the full-scale Passive Containment Cooling System (PCCS) in the Performance ANalysis and Testing of HEat Removal Systems (PANTHERS) facility at Societa Informazioni Termoidrauliche (SIET) in Italy. PANTHERS is a test facility with fall-size prototype beat exchangers for the PCCS in support of the General Electric`s (GE) Simplified Boiling Water Reactor (SBWR) program. PANTHERS tests with a low noncondensable gas concentration and with a high noncondensable gas concentration were analyzed with RELAP5. The results showed that beat transfer rate decreases significantly along the PCCS tubes. In the test case with a higher inlet noncondensable gas fraction, the PCCS removed 35% less heat than in the test case with the lower noncondensable gas fraction. The dominant resistance to the overall heat transfer is the condensation beat transfer resistance inside the tubes. This resistance increased by about 5-fold between the inlet and exit of the tube due to the build up of noncondensable gases along the tube. The RELAP5 calculations also predicted that 4% to 5% of the heat removed to the PCCS pool occurs in the inlet steam piping and PCCS upper and lower headers. These piping needs to be modeled for other tests systems. The full-scale PANTHERS predictions are also compared against 1/400 scale GIRAFFE tests. GIRAFFE has 33% larger heat surface area, but its efficiency is only 15% and 23% higher than PANTHERS for the two cases analyzed This was explained by the high heat transfer resistance inside the tubes near the exit.
Estimation of surface curvature from full-field shape data using principal component analysis
NASA Astrophysics Data System (ADS)
Sharma, Sameer; Vinuchakravarthy, S.; Subramanian, S. J.
2017-01-01
Three-dimensional digital image correlation (3D-DIC) is a popular image-based experimental technique for estimating surface shape, displacements and strains of deforming objects. In this technique, a calibrated stereo rig is used to obtain and stereo-match pairs of images of the object of interest from which the shapes of the imaged surface are then computed using the calibration parameters of the rig. Displacements are obtained by performing an additional temporal correlation of the shapes obtained at various stages of deformation and strains by smoothing and numerically differentiating the displacement data. Since strains are of primary importance in solid mechanics, significant efforts have been put into computation of strains from the measured displacement fields; however, much less attention has been paid to date to computation of curvature from the measured 3D surfaces. In this work, we address this gap by proposing a new method of computing curvature from full-field shape measurements using principal component analysis (PCA) along the lines of a similar work recently proposed to measure strains (Grama and Subramanian 2014 Exp. Mech. 54 913-33). PCA is a multivariate analysis tool that is widely used to reveal relationships between a large number of variables, reduce dimensionality and achieve significant denoising. This technique is applied here to identify dominant principal components in the shape fields measured by 3D-DIC and these principal components are then differentiated systematically to obtain the first and second fundamental forms used in the curvature calculation. The proposed method is first verified using synthetically generated noisy surfaces and then validated experimentally on some real world objects with known ground-truth curvatures.
Progress report on development of intermediate fidelity full assembly analysis methods.
Hu, R.; Fanning, T. H.
2011-09-30
While high fidelity modeling capabilities for various physics phenomena are being pursued under advanced modeling and simulation initiatives under the DOE Office of Nuclear Energy, they generally rely on high-performance computation facilities and are too expensive to be used for parameter-space exploration or design analysis. One-dimensional system codes have been used for a long time and have reached a degree of maturity, but limit their validity to specific applications. Thus, an intermediate fidelity (IF) modeling method is being pursued in this work for a fast-running, modest-fidelity, whole-core transient analyses capability. The new approach is essential for design scoping and engineering analyses and could lead to improvements in the design of the new generations of reactors and to the reduction of uncertainties in safety analysis. This report summarizes the initial effort on the development of the intermediate-fidelity full assembly modeling method. The requirements and the desired merits of the IF approach have been defined. A three-dimensional momentum source model has been developed to model the anisotropic flow in the wire-wrapped rod bundle without the need to resolve the geometric details. It has been confirmed that the momentum source model works well if its affecting region is accurately imposed. The validity of the model is further verified by mesh and parameter sensitivity studies. The developed momentum source model, in principle, can be applied to any wire-wrapped bundle geometries and any flow regimes; while the modeling strategy can be applied to other conditions with complex or distorted geometry, such as flow in blocked channels.
Stanojević, Boban; Osiowy, Carla; Schaefer, Stephan; Bojović, Ksenija; Blagojević, Jelena; Nešić, Milica; Yamashita, Shunichi; Stamenković, Gorana
2011-08-01
Hepatitis B virus (HBV) is classified into 8 genotypes with distinct geographical distribution. Genotype D (HBV/D) has the widest distribution area and is comprised of 7 subgenotypes. Subgenotypes D1, D2 and D3 appear worldwide, while D4-D7 have a more restricted distribution. Within the Mediterranean area, HBV/D and subgenotype D3 are the most prevalent. The purpose of this study was to characterize the full genome of Serbian HBV/D3 isolates by comparison and phylogenetic analysis with HBV/D3 sequences (66 samples) found in GeneBank/DDBJ databases from different parts of the world. Isolates were obtained from three patients diagnosed with chronic hepatitis B (HBsAg+). All three isolates have two very rare nucleotide substitutions, A929T and T150A, which indicate the same ancestor. Phylogenetic analysis of HBV/D3 genome sequences throughout the world follows an ethno-geographical origin of isolates with rare exceptions, which could be explained by human travelling and migration. The geographically close but ethnically different Serbian and Italian isolates clustered in the same subnode, and on a common branch with strains from Northern Canada. To test the apparently close HBV phylogenetic relationship between completely separated patients from Serbia and Northern Canada we analyzed in depth a 440 bp region of the HBsAg from Canadian (n=73) and Serbian (n=70) isolates. The constructed parsimony tree revealed that strains from Serbia and Northern Canada fell along the same branch which indicates independent evolution within regions of each country. Considering that HBsAg sequence has limited variability for phylogenetic analyses, our hypothesis needs further confirmation with more HBV complete genome sequences.
Surface acoustic wave nebulization facilitating lipid mass spectrometric analysis.
Yoon, Sung Hwan; Huang, Yue; Edgar, J Scott; Ting, Ying S; Heron, Scott R; Kao, Yuchieh; Li, Yanyan; Masselon, Christophe D; Ernst, Robert K; Goodlett, David R
2012-08-07
Surface acoustic wave nebulization (SAWN) is a novel method to transfer nonvolatile analytes directly from the aqueous phase to the gas phase for mass spectrometric analysis. The lower ion energetics of SAWN and its planar nature make it appealing for analytically challenging lipid samples. This challenge is a result of their amphipathic nature, labile nature, and tendency to form aggregates, which readily precipitate clogging capillaries used for electrospray ionization (ESI). Here, we report the use of SAWN to characterize the complex glycolipid, lipid A, which serves as the membrane anchor component of lipopolysaccharide (LPS) and has a pronounced tendency to clog nano-ESI capillaries. We also show that unlike ESI SAWN is capable of ionizing labile phospholipids without fragmentation. Lastly, we compare the ease of use of SAWN to the more conventional infusion-based ESI methods and demonstrate the ability to generate higher order tandem mass spectral data of lipid A for automated structure assignment using our previously reported hierarchical tandem mass spectrometry (HiTMS) algorithm. The ease of generating SAWN-MS(n) data combined with HiTMS interpretation offers the potential for high throughput lipid A structure analysis.
Statistical Analysis of Shear Wave Speed in the Uterine Cervix
Carlson, Lindsey C.; Feltovich, Helen; Palmeri, Mark L.; del Rio, Alejandro Muñoz; Hall, Timothy J.
2014-01-01
Although cervical softening is critical in pregnancy, there currently is no objective method for assessing the softness of the cervix. Shear wave speed (SWS) estimation is a noninvasive tool used to measure tissue mechanical properties such as stiffness. The goal of this study was to determine the spatial variability and assess the ability of SWS to classify ripened vs. unripened tissue samples. Ex vivo human hysterectomy samples (n = 22) were collected, a subset (n = 13) were ripened. SWS estimates were made at 4–5 locations along the length of the canal on both anterior and posterior halves. A linear mixed model was used for a robust multivariate analysis. Receiver operating characteristic (ROC) analysis and the area under the ROC curve (AUC) were calculated to describe the utility of SWS to classify ripened vs. unripened tissue samples. Results showed that all variables used in the linear mixed model were significant (p<0.05). Estimates at the mid location for the unripened group were 3.45 ± 0.95 m/s (anterior) and 3.56 ± 0.92 m/s (posterior), and 2.11 ± 0.45 m/s (anterior) and 2.68 ± 0.57 m/s (posterior) for the ripened (p < 0.001). The AUC’s were 0.91 and 0.84 for anterior and posterior respectively suggesting SWS estimates may be useful for quantifying cervical softening. PMID:25392863
Analysis of supercritical vapor explosions using thermal detonation wave theory
Shamoun, B.I.; Corradini, M.L.
1995-09-01
The interaction of certain materials such as Al{sub 2}O{sub 3} with water results in vapor explosions with very high (supercritical) pressures and propagation velocities. A quasi-steady state analysis of supercritical detonation in one-dimensional multiphase flow was applied to analyze experimental data of the KROTOS (26-30) set of experiments conducted at the Joint Research Center at Ispra, Italy. In this work we have applied a new method of solution which allows for partial fragmentation of the fuel in the shock adiabatic thermodynamic model. This method uses known experiment values of the shock pressure and propagation velocity to estimate the initial mixing conditions of the experiment. The fuel and coolant were both considered compressible in this analysis. In KROTOS 26, 28, 29, and 30 the measured values of the shock pressure by the experiment were found to be higher than 25, 50, 100, and 100 Mpa respectively. Using the above data for the wave velocity and our best estimate for the values of the pressure, the predicted minimum values of the fragmented mass of the fuel were found to be 0.026. 0.04, 0.057, and 0.068 kg respectively. The predicted values of the work output corresponding to the above fragmented masses of the fuel were found to be 40, 84, 126, and 150 kJ respectively, with predicted initial void fractions of 112%, 12.5%, 8%, and 6% respectively.
Full-Range Public Health Leadership, Part 2: Qualitative Analysis and Synthesis
Carlton, Erik L.; Holsinger, James W.; Riddell, Martha C.; Bush, Heather
2015-01-01
Public health leadership is an important topic in the era of U.S. health reform, population health innovation, and health system transformation. This study utilized the full-range leadership model in order to examine the public health leadership. We sought to understand local public health leadership from the perspective of local health department leaders and those who work with and for them. Public health leadership was explored through interviews and focus groups with directors (n = 4) and staff (n = 33) from local health departments. Qualitative analytic methods included reflexive journals, code-recode procedures, and member checking, with analysis facilitated by Atlas.ti v.6.0. Qualitative results supported and expanded upon previously reported quantitative findings. Leading by example and providing individual consideration to followers were found to be more important than other leader factors, such as intellectual stimulation, inspirational motivation, or idealized attributes of leaders. Having a clear and competent vision of public health, being able to work collaboratively with other community agencies, and addressing the current challenges to public health with creativity and innovation were also important findings. Idealized leadership behaviors and individual consideration should be the focus of student and professional development. Models that incorporate contextual considerations, such as the situational leadership model, could be utilized to ensure that optimal individual consideration is given to followers. PMID:26217654
A full virial analysis of the prestellar cores in the Ophiuchus molecular cloud
NASA Astrophysics Data System (ADS)
Pattle, Kate; Ward-Thompson, Derek
2015-08-01
We present the first observations of the Ophiuchus molecular cloud performed as part of the James Clerk Maxwell (JCMT) Gould Belt Survey with the SCUBA-2 instrument. We demonstrate methods for combining these data with HARP CO, Herschel and IRAM N2H+ observations in order to accurately quantify the properties of the SCUBA-2 sources in Ophiuchus.We perform a full virial analysis on the starless cores in Ophiuchus, including external pressure. We find that the majority of our cores are either bound or virialised, and that gravity and external pressure are typically of similar importance in confining cores. We find that the critical Bonnor-Ebert stability criterion is not a good indicator of the boundedness of our cores. We determine that N2H+ is a good tracer of the bound material of prestellar cores, and find that non-thermal linewidths decrease substantially between the intermediate-density gas traced by C18O and the high-density gas traced by N2H+, indicating the dissipation of turbulence within cores.We find variation from region to region in the virial balance of cores and the relative contributions of pressure and gravity to core support, as well as variation in the degree to which turbulence is dissipated within cores and in the relative numbers of protostellar and starless sources. We find further support for our previous hypothesis of a global evolutionary gradient from southwest to northeast across Ophiuchus, indicating sequential star formation across the region.
Near Full-Length Sequence Analysis of HIV Type 1 BF Recombinants from Italy
Foley, Brian T.; Rosi, Andrea; Vicenti, Ilaria; Nannetti, Giulio; Meini, Genny; Razzolini, Francesca; Zazzi, Maurizio
2012-01-01
Abstract Recombination between HIV-1 subtypes B and F has generated several circulating and unique recombinant forms, particularly in Latin American areas. In Italy, subtype B is highly prevalent while subtype F is the most common pure non-B subtype. To investigate the recombination pattern in Italian BF recombinant viruses, we characterized full-length sequences derived from 15 adult patients, mostly Italian and infected by the heterosexual route. One of the BF mosaics was a CRF29, three sequences clustered with low bootstrap values with CRF39, CRF40, and CRF42. With the exception of the CRF29-like sequence, the other recombination patterns were unique, but two possible clusters were identified. Analysis of the gp120 V3 domain suggested a possible link with subtype F from Eastern Europe rather than from Latin America, favoring the hypothesis of local recombination between clade B and F viruses over that of import of BF recombinants from Latin America. HIV-1 subtypes B and F appear prone to generation of unique recombinants in Italy, warranting epidemiological surveillance and investigation of a possible clinical significance. PMID:21740272
SPR-based assays enable the full functional analysis of bispecific molecules.
Meschendoerfer, W; Gassner, C; Lipsmeier, F; Regula, J T; Moelleken, J
2017-01-05
The increasing complexity of novel biotherapeutics such as bispecific antibodies or fusion proteins raises new challenges for functional characterization. When compared to standard antibodies, two individual interactions and the inter-dependency of binding events need to be considered for bispecific antibodies. We have previously described an SPR-based assay setup, which enables us to assess the binding activity of a bivalent-bispecific molecule to both targets simultaneously and - in addition to one individual target - in a single setup. However, there might be some pitfalls when applying the bridging assay, e.g. change of antigen activity upon immobilization. Therefore, we have developed an alternative SPR-based assay principle, which allows the individual assessment of both targets in solution. Comparison of data between the assays showed that simultaneous binding can be calculated based on both individual readouts, and revealed a good correlation. Hence, both SPR-based assay principles allow a "full" functional analysis of a bispecific CrossMab in only one assay. The assay principles can be qualified and enable an efficient drug development.
Hydrodynamic analysis of elastic floating collars in random waves
NASA Astrophysics Data System (ADS)
Bai, Xiao-dong; Zhao, Yun-peng; Dong, Guo-hai; Li, Yu-cheng
2015-06-01
As the main load-bearing component of fish cages, the floating collar supports the whole cage and undergoes large deformations. In this paper, a mathematical method is developed to study the motions and elastic deformations of elastic floating collars in random waves. The irregular wave is simulated by the random phase method and the statistical approach and Fourier transfer are applied to analyze the elastic response in both time and frequency domains. The governing equations of motions are established by Newton's second law, and the governing equations of deformations are obtained based on curved beam theory and modal superposition method. In order to validate the numerical model of the floating collar attacked by random waves, a series of physical model tests are conducted. Good relationship between numerical simulation and experimental observations is obtained. The numerical results indicate that the transfer function of out-of-plane and in-plane deformations increase with the increasing of wave frequency. In the frequency range between 0.6 Hz and 1.1 Hz, a linear relationship exists between the wave elevations and the deformations. The average phase difference between the wave elevation and out-of-plane deformation is 60° with waves leading and the phase between the wave elevation and in-plane deformation is 10° with waves lagging. In addition, the effect of fish net on the elastic response is analyzed. The results suggest that the deformation of the floating collar with fish net is a little larger than that without net.
NASA Astrophysics Data System (ADS)
Dombrowski, M. P.; Labelle, J. W.; Kletzing, C.; Bounds, S. R.; Kaeppler, S. R.
2013-12-01
Bursty Langmuir waves have been interpreted as the result of the superposition of multiple Langmuir normal-mode waves, with the resultant modulation being the beat pattern between waves with e.g. 10 kHz frequency differences. The normal-mode waves could be generated either through wave-wave interactions with VLF waves, or through independent linear processes. The CHARM II sounding rocket was launched into a substorm at 9:49 UT on 15 February 2010, from the Poker Flat Research Range in Alaska. The primary instruments included the Dartmouth High-Frequency Experiment (HFE), a receiver system which effectively yields continuous (100% duty cycle) E-field waveform measurements up to 5 MHz, as well as a number of charged particle detectors, including a wave-particle correlator. The payload also included a magnetometer and several low-frequency wave instruments. CHARM II encountered several regions of strong Langmuir wave activity throughout its 15-minute flight, including several hundred discrete Langmuir-wave bursts. We show results of a statistical analysis of CHARM II data for the entire flight, comparing HFE data with the other payload instruments, specifically looking at timings and correlations between bursty Langmuir waves, Alfvén and whistler-mode waves, and electrons precipitating parallel to the magnetic field. Following a similar analysis on TRICE dayside sounding rocket data, we also calculate the fraction of correlated waves with VLF waves at appropriate frequencies to support the wave-wave interaction bursty Langmuir wave generation mechanism, and compare to results from CHARM II nightside data.
Analysis of magnetometer data/wave signals in the Earth's magnetosphere
NASA Technical Reports Server (NTRS)
Engebretson, Mark J.
1993-01-01
Work on the reduction and analysis of Dynamics Explorer (DE) satellite magnetometer data with special emphasis on the ULF fluctuations and waves evident in such data is described. Research focused on the following: (1) studies of Pc 1 wave packets near the plasmapause; (2) satellite-ground pulsation study; (3) support for studies of ion energization processes; (4) search for Pc 1 wave events in 1981 DE 1 data; (5) study of Pc 3-5 events observed simultaneously by DE 1 and by AMPTE CCE; (6) support for studies of electromagnetic transients on DE 1; and (7) analysis of wave events induced by sudden impulses.
Seismic response of a full-scale wind turbine tower using experimental and numerical modal analysis
NASA Astrophysics Data System (ADS)
Kandil, Kamel Sayed Ahmad; Saudi, Ghada N.; Eltaly, Boshra Aboul-Anen; El-khier, Mostafa Mahmoud Abo
2016-12-01
Wind turbine technology has developed tremendously over the past years. In Egypt, the Zafarana wind farm is currently generating at a capacity of 517 MW, making it one of the largest onshore wind farms in the world. It is located in an active seismic zone along the west side of the Gulf of Suez. Accordingly, seismic risk assessment is demanded for studying the structural integrity of wind towers under expected seismic hazard events. In the context of ongoing joint Egypt-US research project "Seismic Risk Assessment of Wind Turbine Towers in Zafarana wind Farm Egypt" (Project ID: 4588), this paper describes the dynamic performance investigation of an existing Nordex N43 wind turbine tower. Both experimental and numerical work are illustrated explaining the methodology adopted to investigate the dynamic behavior of the tower under seismic load. Field dynamic testing of the full-scale tower was performed using ambient vibration techniques (AVT). Both frequency domain and time domain methods were utilized to identify the actual dynamic properties of the tower as built in the site. Mainly, the natural frequencies, their corresponding mode shapes and damping ratios of the tower were successfully identified using AVT. A vibration-based finite element model (FEM) was constructed using ANSYS V.12 software. The numerical and experimental results of modal analysis were both compared for matching purpose. Using different simulation considerations, the initial FEM was updated to finally match the experimental results with good agreement. Using the final updated FEM, the response of the tower under the AQABA earthquake excitation was investigated. Time history analysis was conducted to define the seismic response of the tower in terms of the structural stresses and displacements. This work is considered as one of the pioneer structural studies of the wind turbine towers in Egypt. Identification of the actual dynamic properties of the existing tower was successfully performed
Estimation of Arterial Stiffness by Time-Frequency Analysis of Pulse Wave
NASA Astrophysics Data System (ADS)
Saito, Masashi; Yamamoto, Yuya; Shibayama, Yuka; Matsukawa, Mami; Watanabe, Yoshiaki; Furuya, Mio; Asada, Takaaki
2011-07-01
Evaluation of a pulse wave is effective for the early diagnosis of arteriosclerosis because the pulse wave contains the reflected wave that is the age- and stiffness-dependent component. In this study, we attempted to extract the parameter reflecting the component by pulse wave analysis using continuous wavelet transform. The Morlet wavelet was used as the mother wavelet. We then investigated the relationship between the parameter and the reflected wave that was extracted from the pulse wave by our previously reported separation technique. Consequently, the result of wavelet transform of the differentiated pulse waveform changed markedly owing to age and had medium correlation with the peak of the reflected wave (R=0.68).
NASA Astrophysics Data System (ADS)
Mokrousov, Y.; Bihlmayer, G.; Blügel, S.
2005-07-01
We present an implementation of the full-potential linearized augmented plane-wave (FLAPW) method for carrying out ab initio calculations of the ground state electronic properties of (magnetic) metallic nanowires and nanotubes based on the density-functional theory (DFT). The method is truly one-dimensional, uses explicitly a wire geometry and is realized as an extension of the FLEUR code. It includes a wide variety of chiral symmetries known for tubular and other one-dimensional systems. A comparative study shows that in this geometry computations are considerably faster than the widely used supercell approach. The method was applied to some typical model structures explored in the field of nanospintronics: the gold nanowire Au(6,0), the free-standing Fe monowire, and the hybrid structure Fe@Au(6,0). Their atomic structures are determined by total energy minimization and force calculations. We calculated the magnetic properties including the magnetocrystalline anisotropy energies, the band structures, and densities of states in these systems using the local density approximation (LDA) and the generalized gradient approximation (GGA) to the DFT. The results agree nicely with the data available in the literature. We found that Fe wires are ferromagnetic and are prone to a Peierls dimerization. The Fe filled gold nanotube shows a large negative spin polarization at the Fermi level, which makes this structure a possible candidate for spin-dependent transport applications in the field of spintronics. The Au tube encasing the Fe wire changes the magnetization direction of the Fe wire and increases the magnetocrystalline anisotropy energy by an order of magnitude.
Analysis of meteorological parameters of different extreme heat waves
Technology Transfer Automated Retrieval System (TEKTRAN)
Heat waves have caused severe losses in beef cattle feedlots and dairies in different areas of the cattle producing areas of the world. A comparison of climatic conditions that have resulted in cattle deaths has been completed. Analyses of lethal heat waves in northeast Nebraska in 1999 and north ...
Polar Plasma Wave Investigation Data Analysis in the Extended Mission
NASA Technical Reports Server (NTRS)
Gurnett, Donald A.; Menietti, J. D.
2003-01-01
The low latitude boundary layer (LLBL) is a region where solar wind momentum and energy is transferred to the magnetosphere. Enhanced "broadband" electric plasma waves from less than 5 Hz to l0(exp 5) Hz and magnetic waves from less than 5 Hz to the electron cyclotron frequency are characteristic of the LLBL. Analyses of Polar plasma waves show that these "broadband" waves are actually discrete electrostatic and electromagnetic modes as well as solitary bipolar pulses (electron holes). It is noted that all wave modes can be generated by approx. 100 eV to approx. 10 keV auroral electrons and protons. We will review wave-particle interactions, with focus on cross- diffusion rates and the contributions of such interactions toward the formation of the boundary layer. In summary, we will present a scenario where the global solar wind-magnetosphere interaction is responsible for the auroral zone particle beams, and hence for the generation of plasma waves and the formation of the boundary layer. It is speculated that all planetary magnetospheres will have boundary layers and they will be characterized by similar currents and plasma wave modes.
Polar Plasma Wave Investigation Data Analysis in the Extended Mission
NASA Technical Reports Server (NTRS)
Gurnett, Donald A.
2004-01-01
The low latitude boundary layer (LLBL) is a region where solar wind momentum and energy is transferred to the magnetosphere. Enhanced "broadband" electric plasma waves from less than 5 Hz to 10(exp 5) Hz and magnetic waves from less than 5 Hz to the electron cyclotron frequency are characteristic of the LLBL. Analyses of Polar plasma waves show that these "broadband" waves are actually discrete electrostatic and electromagnetic modes as well as solitary bipolar pulses (electron holes). It is noted that all wave modes can be generated by approx. 100 eV to approx. 10 keV auroral electrons and protons. We will review wave-particle interactions, with focus on cross-diffusion rates and the contributions of such interactions toward the formation of the boundary layer. In summary, we will present a scenario where the global solar wind-magnetosphere interaction is responsible for the auroral zone particle beams, and hence for the generation of plasma waves and the formation of the boundary layer. It is speculated that all planetary magnetospheres will have boundary layers and they will be characterized by similar currents and plasma wave modes.
Time dependent wave envelope finite difference analysis of sound propagation
NASA Technical Reports Server (NTRS)
Baumeister, K. J.
1984-01-01
A transient finite difference wave envelope formulation is presented for sound propagation, without steady flow. Before the finite difference equations are formulated, the governing wave equation is first transformed to a form whose solution tends not to oscillate along the propagation direction. This transformation reduces the required number of grid points by an order of magnitude. Physically, the transformed pressure represents the amplitude of the conventional sound wave. The derivation for the wave envelope transient wave equation and appropriate boundary conditions are presented as well as the difference equations and stability requirements. To illustrate the method, example solutions are presented for sound propagation in a straight hard wall duct and in a two dimensional straight soft wall duct. The numerical results are in good agreement with exact analytical results.
Gravitational Wave Detection of Compact Binaries Through Multivariate Analysis
NASA Astrophysics Data System (ADS)
Atallah, Dany Victor; Dorrington, Iain; Sutton, Patrick
2017-01-01
The first detection of gravitational waves (GW), GW150914, as produced by a binary black hole merger, has ushered in the era of GW astronomy. The detection technique used to find GW150914 considered only a fraction of the information available describing the candidate event: mainly the detector signal to noise ratios and chi-squared values. In hopes of greatly increasing detection rates, we want to take advantage of all the information available about candidate events. We employ a technique called Multivariate Analysis (MVA) to improve LIGO sensitivity to GW signals. MVA techniques are efficient ways to scan high dimensional data spaces for signal/noise classification. Our goal is to use MVA to classify compact-object binary coalescence (CBC) events composed of any combination of black holes and neutron stars. CBC waveforms are modeled through numerical relativity. Templates of the modeled waveforms are used to search for CBCs and quantify candidate events. Different MVA pipelines are under investigation to look for CBC signals and un-modelled signals, with promising results. One such MVA pipeline used for the un-modelled search can theoretically analyze far more data than the MVA pipelines currently explored for CBCs, potentially making a more powerful classifier. In principle, this extra information could improve the sensitivity to GW signals. We will present the results from our efforts to adapt an MVA pipeline used in the un-modelled search to classify candidate events from the CBC search.
Analysis of a Large Orbit Backward Wave Oscillator
NASA Astrophysics Data System (ADS)
Choyal, Y.; Watanabe, T.; Minami, K.; Granatstein, V. L.
2003-12-01
The effect of the finite axial magnetic field on the excitation of a backward wave oscillator (BWO) is investigated. The driver beam is assumed to be mono-energetic helical electron beam such that all the constituent electrons have their gyration centers on the axis of the slow wave structure (SWS). Such a beam supports negative energy fast and slow cyclotron modes (FCM and SCM) that can excite the structure modes in the SWS. This may contribute to the microwave generation in BWO. All the previous analyses on BWO have assumed the electrons without the initial perpendicular velocity component. The formulation is as follows: The thin annular large orbit beam is perturbed and the first order perturbations in velocity and density are obtained. Integrating radially across the beam, we derive the expression for surface current density. It can be expressed in terms of the azimuthal and axial components of the perturbed electric field. The boundary conditions on the beam surface are as follows. (a) Matching of the continuous axial and azimuthal components of electric field and (b) Matching of the discontinuous axial and azimuthal magnetic fields across the beam by the presence of surface current density. They are augmented by the requirement of Floquet periodicity on the RF fields and the boundary conditions that the tangential electric field should vanish on the metal SWS surface, 6(2N+1) × 6(2N+1) order determinant that must to be zero and this is the dispersion relation of the system. Here, 2N+1 is the number of Floquet harmonics involved. Numerical analysis is made assuming N=4 and appropriate practical experimental parameters. The excitations of the unstable non-axisymmetric Q-TE11 and Q-TM11 modes caused by negative energy FCM in addition to unstable axisymmetric Q-TM01 mode caused by slow beam mode that is identical to conventional BWOs are observed. Defining α as the ratio of the transverse to the longitudinal velocity components of the beam electrons, it is
Stochastic analysis of shear-wave splitting length scales
NASA Astrophysics Data System (ADS)
Becker, Thorsten W.; Browaeys, Jules T.; Jordan, Thomas H.
2007-07-01
The coherence of azimuthal seismic anisotropy, as inferred from shear-wave splitting measurements, decreases with the relative distance between stations. Stochastic models of a two-dimensional vector field defined by a von Karma'n [T. von Karma'n, Progress in the statistical theory of turbulence, J. Mar. Res., 7 (1948) 252-264.] autocorrelation function with horizontal correlation length L provide a useful means to evaluate this heterogeneity and coherence lengths. We use the compilation of SKS splitting measurements by Fouch [M. Fouch, Upper mantle anisotropy database, accessed in 06/2006, http://geophysics.asu.edu/anisotropy/upper/] and supplement it with additional studies, including automated measurements by Evans et al. [Evans, M.S., Kendall, J.-M., Willemann, R.J., 2006. Automated SKS splitting and upper-mantle anisotropy beneath Canadian seismic stations, Geophys. J. Int. 165, 931-942, Evans, M.S., Kendall, J.-M., Willemann, R.J. Automated splitting project database, Online at http://www.isc.ac.uk/SKS/, accessed 02/2006]. The correlation lengths of this dataset depend on the geologic setting in the continental regions: in young Phanerozoic orogens and magmatic zones L ˜ 600 km, smaller than the smooth L ˜ 1600 km patterns in tectonically more stable regions such as Phanerozoic platforms. Our interpretation is that the relatively large coherence underneath older crust reflects large-scale tectonic processes (e.g. continent-continent collisions) that are frozen into the tectosphere. In younger continental regions, smaller scale flow (e.g. slab anomaly induced) may predominantly affect anisotropy. In this view, remnant anisotropy is dominant in the old continents and deformation-induced anisotropy caused by recent asthenospheric flow is dominant in active continental regions and underneath oceanic plates. Auxiliary analysis of surface-wave anisotropy and combined mantle flow and anisotropic texture modeling is consistent with this suggestion. In continental
Statistical Analysis of Acoustic Wave Parameters Near Solar Active Regions
NASA Astrophysics Data System (ADS)
Rabello-Soares, M. Cristina; Bogart, Richard S.; Scherrer, Philip H.
2016-08-01
In order to quantify the influence of magnetic fields on acoustic mode parameters and flows in and around active regions, we analyze the differences in the parameters in magnetically quiet regions nearby an active region (which we call “nearby regions”), compared with those of quiet regions at the same disk locations for which there are no neighboring active regions. We also compare the mode parameters in active regions with those in comparably located quiet regions. Our analysis is based on ring-diagram analysis of all active regions observed by the Helioseismic and Magnetic Imager (HMI) during almost five years. We find that the frequency at which the mode amplitude changes from attenuation to amplification in the quiet nearby regions is around 4.2 mHz, in contrast to the active regions, for which it is about 5.1 mHz. This amplitude enhacement (the “acoustic halo effect”) is as large as that observed in the active regions, and has a very weak dependence on the wave propagation direction. The mode energy difference in nearby regions also changes from a deficit to an excess at around 4.2 mHz, but averages to zero over all modes. The frequency difference in nearby regions increases with increasing frequency until a point at which the frequency shifts turn over sharply, as in active regions. However, this turnover occurs around 4.9 mHz, which is significantly below the acoustic cutoff frequency. Inverting the horizontal flow parameters in the direction of the neigboring active regions, we find flows that are consistent with a model of the thermal energy flow being blocked directly below the active region.
Acoustic wave network and multivariate analysis for biosensing in space
NASA Astrophysics Data System (ADS)
Jayarajah, Christine N.; Thompson, Michael
2005-03-01
Bioanalytical techniques play an important role in monitoring the effects of environmental stress factors on fundamental life processes. In terms of space flight and extraterrestrial research, radiation, altered and microgravity are known to induce changes in gene expression. We report the use of an on-line transverse shear mode (TSM) acoustic wave biosensor to detect the initiation of gene transcription and DNA — drug binding. Since this biosensor offers real-time, label free monitoring of biological processes, it is possible to detect sequential binding steps as demonstrated in this paper. Furthermore, this sensor responds to several factors in the liquid phase such as viscosity, elasticity, surface tension, charge distribution and mass loading, which can in turn be influenced by specific gravity. The sensing device is a piezoelectric quartz crystal onto which the probe molecule (DNA in this case) is immobilized. Change in resonance frequency of the crystal in response to the binding of the target molecule(s), RNA polymerase and actinomycin-D, is fit to an equivalent circuit model from which multidimensional data is extracted. By performing multivariate analysis on this data we are able to observe interactions between several of these data series representing parameters such as motional resistance and capacitance. As well, we are able to observe the dominating parameters (for instance, frequency vs. motional resistance, which in turn can correspond to mass loading vs. energy dissipation) during the course of the experiment, as they vary between the different steps. Such advantages offered by the TSM sensor along with multivariate analysis are indispensable for biotechnological work under the influence of microgravity as several variables come into play.
Multi-channel analysis of surface waves MASW of models with high shear-wave velocity contrast
Ivanov, J.; Miller, R.D.; Peterie, S.; Zeng, C.; Xia, J.; Schwenk, T.
2011-01-01
We use the multi-channel analysis of surface waves MASW method to analyze synthetic seismic data calculated using models with high shear-wave velocity Vs contrast. The MASW dispersion-curve images of the Rayleigh wave are obtained using various sets of source-offset and spread-size configurations from the synthetic seismic data and compared with the theoretically calculated fundamental- and higher-mode dispersion-curves. Such tests showed that most of the dispersion-curve images are dominated by higher-mode energy at the low frequencies, especially when analyzing data from long receiver offsets and thus significantly divert from numerically expected dispersion-curve trends, which can lead to significant Vs overestimation. Further analysis showed that using data with relatively short spread lengths and source offsets can image the desired fundamental-mode of the Rayleigh wave that matches the numerically expected dispersion-curve pattern. As a result, it was concluded that it might be possible to avoid higher-mode contamination at low frequencies at sites with high Vs contrast by appropriate selection of spread size and seismic source offset. ?? 2011 Society of Exploration Geophysicists.
The dynamics of the 2001 Etna eruption as seen by full moment tensor analysis
NASA Astrophysics Data System (ADS)
Saraò, A.; Cocina, O.; Privitera, E.; Panza, G. F.
2010-05-01
The Mt. Etna eruption of July 2001 was announced by severe seismic activity and by the opening of a 7-km-long zone of densely distributed fractures. The large amount of data collected gave a unique opportunity to study the magma migration process and to infer the position and geometry of the uprising dyke. Results from multidisciplinary approaches suggest that the observed phenomenology was the result of the rapid intrusion of a vertical dyke, oriented roughly N-S and located a few km south of the summit region. To add new constraints to the dynamics of the eruption process, in this study we determine the full seismic moment tensors of 61 earthquakes, selected among those occurring between July 12 and July 18 (Md >= 2.2), located in a depth ranging from 1 km above sea level (a.s.l.) to 3 km below sea level (b.s.l.). At the beginning of the seismic swarm, the dominant component of the seismic source tensor is double-couple percentage (around 65 per cent on average) statistical significant at 95 per cent confidence level and in the following hours the non-double-couple components increase at the expenses of the double-couple. Such observations are related well with the system of fractures formed just before the eruption, whereas the increasing non-double-couple components can be explained as the response of the confining rocks to the rising magma and degassing processes. The type of focal mechanisms retrieved are predominantly of normal fault type (44 per cent), strike slip (30 per cent) and thrust mechanisms (9 per cent), and outline a scenario that concurs with the stress regime induced by a dyke injection. The space-time analysis of seismic source locations and source moment tensors (1) confirms the evidence of a vertical dyke emplacement that fed the 2001 lateral eruption and (2) adds new insights to support the hypothesis of the injection of a second aborted dyke, 2 km SE from the fractures zone.
The Extended GMRT Radio Halo Survey. II. Further results and analysis of the full sample
NASA Astrophysics Data System (ADS)
Kale, R.; Venturi, T.; Giacintucci, S.; Dallacasa, D.; Cassano, R.; Brunetti, G.; Cuciti, V.; Macario, G.; Athreya, R.
2015-07-01
The intra-cluster medium contains cosmic rays and magnetic fields that are manifested through the large scale synchrotron sources, termed radio haloes, relics, and mini-haloes. The Extended Giant Metrewave Radio Telescope (GMRT) Radio Halo Survey (EGRHS) is an extension of the GMRT Radio Halo Survey (GRHS) designed to search for radio haloes using GMRT 610/235 MHz observations. The GRHS and EGRHS consists of 64 clusters in the redshift range 0.2-0.4 that have an X-ray luminosity larger than 5 × 1044 erg s-1 in the 0.1-2.4 keV band and declination, δ > -31° in the REFLEX and eBCS X-ray cluster catalogues. In this second paper in the series, GMRT 610/235 MHz data on the last batch of 11 galaxy clusters and the statistical analysis of the full sample are presented. A new mini-halo in RX J2129.6+0005 and candidate diffuse sources in Z5247, A2552, and Z1953 have been discovered. A unique feature of this survey are the upper limits on the detections of 1 Mpc sized radio haloes; 4 new are presented here, making a total of 31 in the survey. Of the sample, 58 clusters with adequately sensitive radio information were used to obtain the most accurate occurrence fractions so far. The occurrence fractions of radio haloes, mini-haloes and relics in our sample are ~22%, ~16% and ~5%, respectively. The P1.4 GHz-LX diagrams for the radio haloes and mini-haloes are presented. The morphological estimators - centroid shift (w), concentration parameter (c), and power ratios (P3/P0) derived from the Chandra X-ray images - are used as proxies for the dynamical states of the GRHS and EGRHS clusters. The clusters with radio haloes and mini-haloes occupy distinct quadrants in the c-w, c-P3/P0 and w-P3/P0 planes, corresponding to the more and less morphological disturbance, respectively. The non-detections span both the quadrants. Appendices are available in electronic form at http://www.aanda.org
Analysis of 4,664 high-quality sequence-finished poplar full-length
Ralph, S.; Gunter, Lee E; Tuskan, Gerald A; Douglas, Carl; Holt, Robert A.; Jones, Steven; Marra, Marco; Bohlmann, J.
2008-01-01
The genus Populus includes poplars, aspens and cottonwoods, which will be collectively referred to as poplars hereafter unless otherwise specified. Poplars are the dominant tree species in many forest ecosystems in the Northern Hemisphere and are of substantial economic value in plantation forestry. Poplar has been established as a model system for genomics studies of growth, development, and adaptation of woody perennial plants including secondary xylem formation, dormancy, adaptation to local environments, and biotic interactions. As part of the poplar genome sequencing project and the development of genomic resources for poplar, we have generated a full-length (FL)-cDNA collection using the biotinylated CAP trapper method. We constructed four FLcDNA libraries using RNA from xylem, phloem and cambium, and green shoot tips and leaves from the P. trichocarpa Nisqually-1 genotype, as well as insect-attacked leaves of the P. trichocarpa x P. deltoides hybrid. Following careful selection of candidate cDNA clones, we used a combined strategy of paired end reads and primer walking to generate a set of 4,664 high-accuracy, sequence-verified FLcDNAs, which clustered into 3,990 putative unique genes. Mapping FLcDNAs to the poplar genome sequence combined with BLAST comparisons to previously predicted protein coding sequences in the poplar genome identified 39 FLcDNAs that likely localize to gaps in the current genome sequence assembly. Another 173 FLcDNAs mapped to the genome sequence but were not included among the previously predicted genes in the poplar genome. Comparative sequence analysis against Arabidopsis thaliana and other species in the non-redundant database of GenBank revealed that 11.5% of the poplar FLcDNAs display no significant sequence similarity to other plant proteins. By mapping the poplar FLcDNAs against transcriptome data previously obtained with a 15.5 K cDNA microarray, we identified 153 FLcDNA clones for genes that were differentially expressed in
Stochastic analysis and modeling of abnormally large waves
NASA Astrophysics Data System (ADS)
Kuznetsov, Konstantin; Shamin, Roman; Yudin, Aleksandr
2016-04-01
In this work stochastics of amplitude characteristics of waves during the freak waves formation was estimated. Also amplitude characteristics of freak wave was modeling with the help of the developed Markov model on the basis of in-situ and numerical experiments. Simulation using the Markov model showed a great similarity of results of in-situ wave measurements[1], results of directly calculating the Euler equations[2] and stochastic modeling data. This work is supported by grant of Russian Foundation for Basic Research (RFBR) n°16-35-00526. 1. K. I. Kuznetsov, A. A. Kurkin, E. N. Pelinovsky and P. D. Kovalev Features of Wind Waves at the Southeastern Coast of Sakhalin according to Bottom Pressure Measurements //Izvestiya, Atmospheric and Oceanic Physics, 2014, Vol. 50, No. 2, pp. 213-220. DOI: 10.1134/S0001433814020066. 2. R.V. Shamin, V.E. Zakharov, A.I. Dyachenko. How probability for freak wave formation can be found // THE EUROPEAN PHYSICAL JOURNAL - SPECIAL TOPICS Volume 185, Number 1, 113-124, DOI: 10.1140/epjst/e2010-01242-y 3.E. N. Pelinovsky, K. I. Kuznetsov, J. Touboul, A. A. Kurkin Bottom pressure caused by passage of a solitary wave within the strongly nonlinear Green-Naghdi model //Doklady Physics, April 2015, Volume 60, Issue 4, pp 171-174. DOI: 10.1134/S1028335815040035
Analysis of a pneumatic forebody flow control concept about a full aircraft geometry
NASA Technical Reports Server (NTRS)
Gee, Ken; Rizk, Yehia M.; Murman, Scott M.; Lanser, Wendy R.; Meyn, Larry A.; Schiff, Lewis B.
1992-01-01
A full aircraft geometry is used to computationally analyze the effectiveness of a pneumatic forebody flow control concept. An overset grid technique is employed to model the aircraft and slot geometry. Steady-state solutions for both isolated forebody and full aircraft configurations are carried out using a thin-layer Navier-Stokes flow solver. A solution obtained using the full aircraft geometry and a flight sideslip condition investigates the effect of sideslip on the leading edge extention vortex burst point. A no-sideslip blowing solution using the isolated forebody at full-scale wind tunnel test conditions is compared with experimental data to determine the accuracy of the numerical method. A solution employing the full geometry and slot blowing at flight conditions is obtained.
New Software for Long-Term Storage and Analysis of Seismic Wave Data
NASA Astrophysics Data System (ADS)
Cervelli, D. P.; Cervelli, P. F.; Murray, T. L.
2004-12-01
Large seismic networks generate a substantial quantity of data that must be first archived, and then disseminated, visualized, and analyzed, in real-time, in the office or from afar. To achieve these goals for the Alaska Volcano Observatory we developed two software packages: Winston, a database for storing seismic wave data, and Swarm, an application for analyzing and browsing the data. We also modified an existing package, Valve, an internet web-browser based interface to various data sets developed at the Hawaiian Volcano Observatory, to communicate with Winston. These programs provide users with the tools necessary to monitor many commonly used geophysical parameters. Winston, Wave Information Storage Network, uses a vendor-neutral SQL database to store seismic wave data. Winston's primary design goal was simple: develop a more robust, scalable, long-term replacement for the Earthworm waveserver. Access to data within the Winston database is through a scalable internet based server application, an Earthworm waveserver emulator, or directly via SQL queries. Some benefits of using an SQL database are easy backups and exports, speed, and reliability. Swarm, Seismic Wave Analysis and Real-time Monitor, is a stand-alone application that was designed to replace the traditional drum helicorder and computer wave viewer with an intuitive and interactive interface for rapidly assessing volcanic hazard, browsing through past data, and analyzing waveforms. Users can easily view waves in traditional analytic ways, such as frequency spectra or spectrograms, and employ standard analytic tools like filtering. Swarm allows efficient dissemination of data and breaks cross-disciplinary barriers by creating an accessible interface to seismic data for non-seismologists. Swarm currently operates with many seismic data sources including Earthworm waveservers and SEED files. Lastly, Swarm can be a valuable education and outreach tool by using its Kiosk Mode: a full-screen mode that
Multichannel analysis of surface waves to map bedrock
Miller, Richard D.; Xia, Jianghai; Park, Choon B.; Ivanov, Julian M.
1999-01-01
High velocity gradients within the shear wave velocity field consistent with drill confirmed bedrock are considered diagnostic of the bedrock surface and were used to map the top of bedrock on all four lines connected at this site. Calculating the shear wave velocity field from surface wave arrivals was accomplished with a high degree of accuracy regardless of cultural noise. Improved resolution on the surface of the bedrock provides insight into the texture of bedrock and permits identification and appraisal of short wavelength variations in the bedrock surface.
Ritboon, Atirach; Daengngam, Chalongrat; Pengpan, Teparksorn
2016-08-15
Biakynicki-Birula introduced a photon wave function similar to the matter wave function that satisfies the Schrödinger equation. Its second quantization form can be applied to investigate nonlinear optics at nearly full quantum level. In this paper, we applied the photon wave function formalism to analyze both linear optical processes in the well-known Mach–Zehnder interferometer and nonlinear optical processes for sum-frequency generation in dispersive and lossless medium. Results by photon wave function formalism agree with the well-established Maxwell treatments and existing experimental verifications.
Subharmonic wave analysis in crack using the developed FEM
NASA Astrophysics Data System (ADS)
Mihara, Tsuyoshi; Shimaya, Koji; Ikegami, Yasushi; Furukawa, Takashi; Komura, Ichiro
2012-09-01
As the first step of the improvement of developed FEM code to extend the subharmonic wave generation at nano scale gap crack, we investigated the basic crack model for accurate simulator of subharmonic behavior using the voxel mesh FEM code.
Analysis of wave propagation in periodic 3D waveguides
NASA Astrophysics Data System (ADS)
Schaal, Christoph; Bischoff, Stefan; Gaul, Lothar
2013-11-01
Structural Health Monitoring (SHM) is a growing research field in the realm of civil engineering. SHM concepts are implemented using integrated sensors and actuators to evaluate the state of a structure. Within this work, wave-based techniques are addressed. Dispersion effects for propagating waves in waveguides of different materials are analyzed for various different cross-sections. Since analytical theory is limited, a general approach based on the Waveguide Finite Element Method is applied. Numerical results are verified experimentally.
Ocean Surface Wave Optical Roughness: Analysis of Innovative Measurements
2013-12-16
Banner, M . L ., C. J. Zappa and J. Gemmrich (2013), A note on Phillips’ spectral framework for ocean whitecaps, Journal of Physical Oceanography, in...verification for the COARE algorithm, J. Climate, 16, 571-591. Gemmrich, J. R., M . L . Banner, and C. Garrett (2008), Spectrally resolved energy dissipation...and momentum flux of breaking waves, J. Phys. Oceanogr., 38, 1296-1312. Gemmrich, J. R., C. J. Zappa, M . L . Banner, and R. P. Morison (2013), Wave
Self-adaptive method for high frequency multi-channel analysis of surface wave method
Technology Transfer Automated Retrieval System (TEKTRAN)
When the high frequency multi-channel analysis of surface waves (MASW) method is conducted to explore soil properties in the vadose zone, existing rules for selecting the near offset and spread lengths cannot satisfy the requirements of planar dominant Rayleigh waves for all frequencies of interest ...
Time and space analysis of turbulence of gravity surface waves
NASA Astrophysics Data System (ADS)
Mordant, Nicolas; Aubourg, Quentin; Viboud, Samuel; Sommeria, Joel
2016-11-01
Wave turbulence is a statistical state made of a very large number of nonlinearly interacting waves. The Weak Turbulence Theory was developed to describe such a situation in the weakly nonlinear regime. Although, oceanic data tend to be compatible with the theory, laboratory data fail to fulfill the theoretical predictions. A space-time resolved measurement of the waves have proven to be especially fruitful to identify the mechanism at play in turbulence of gravity-capillary waves. We developed an image processing algorithm to measure the motion of the surface of water with both space and time resolution. We first seed the surface with slightly buoyant polystyrene particles and use 3 cameras to reconstruct the surface. Our stereoscopic algorithm is coupled to PIV so that to obtain both the surface deformation and the velocity of the water surface. Such a coupling is shown to improve the sensitivity of the measurement by one order of magnitude. We use this technique to probe the existence of weakly nonlinear turbulence excited by two small wedge wavemakers in a 13-m diameter wave flume. We observe a truly weakly nonlinear regime of isotropic wave turbulence. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant Agreement No 647018-WATU).
A sequential assimilation scheme applied to global wave analysis and prediction
NASA Astrophysics Data System (ADS)
Lionello, P.; Günther, H.; Hansen, B.
1995-01-01
This paper examines the results of the assimilation of satellite Significant Wave Height (SWH) observations in a global wave prediction model. The model used is the third generation wave model WAM. The assimilation is carried out using a sequential (single time level) scheme. Each assimilation step is split into two parts. The analysed SWH field is built by Optimal Interpolation, and the analysed spectrum is successively derived from it and from the first guess spectrum. The period used in the study is February 1992, and the altimeter data have been provided by the ERS-1 satellite. The results show positive effects of the assimilation on both wave analysis and forecast.
Analysis of an axial compressor blade vibration based on wave reflection theory
NASA Technical Reports Server (NTRS)
Owczarek, J. A.
1983-01-01
The paper describes application of the theory of wave reflection in turbomachines to rotor blade vibrations measured in an axial compressor stage. The blade vibrations analyzed could not be predicted using various flutter prediction techniques. The wave reflection theory, first advanced in 1966, is expanded, and more general equations for the rotor blade excitation frequencies are derived. The results of the analysis indicate that all examined rotor blade vibrations can be explained by forced excitations caused by reflecting waves (pressure pulses). Wave reflections between the rotor blades and both the upstream and downstream stator vanes had to be considered.
Flutter and forced response of mistuned rotors using standing wave analysis
NASA Technical Reports Server (NTRS)
Bundas, D. J.; Dungundji, J.
1983-01-01
A standing wave approach is applied to the analysis of the flutter and forced response of tuned and mistuned rotors. The traditional traveling wave cascade airforces are recast into standing wave arbitrary motion form using Pade approximants, and the resulting equations of motion are written in the matrix form. Applications for vibration modes, flutter, and forced response are discussed. It is noted that the standing wave methods may prove to be more versatile for dealing with certain applications, such as coupling flutter with forced response and dynamic shaft problems, transient impulses on the rotor, low-order engine excitation, bearing motion, and mistuning effects in rotors.
Expected sources and data analysis on laser interferometric gravitational wave detector
NASA Astrophysics Data System (ADS)
Kanda, Nobuyuki
2001-10-01
The direct detection of gravitational wave has been expected for physics in strong gravitational field, and for a new deep probe for astronomical objects. Recently, some projects of large-scale laser interferometric gravitational wave detector compete for the first detection of gravitational wave. Our project TAMA300 which is placed in NAOJ, achieved worlds best sensitivity and long stable operation as a realistic observatory. In this document, we will give a brief description of gravitational wave detection, expected sources, and TAMA's data analysis.
NASA Astrophysics Data System (ADS)
Lembege, B.; Savoini, P.; Stienlet, J.
2013-05-01
Two distinct ion populations backstreaming into the solar wind have been clearly evidenced by various space missions within the quasi-perpendicular region of the ion foreshock located upstream of the Earth's Bow shock (i.e. for 45° ≤ Theta_Bn ≤ 90°, where Theta_Bn is the angle between the shock normal and the upstream magnetostatic field): (i) field-aligned ion beams (« FAB ») characterized by a gyrotropic distribution, and (ii) gyro-phase bunched ions («GPB »), characterized by a NON gyrotropic distribution. The origin of these backstreaming ions has not been clearly identified and is presently analyzed with the help of 2D PIC simulation of a curved shock, where full curvature effects, time of flight effects and both electrons and ions dynamics are fully described within a self consistent approach. Present simulations evidence that these two populations can be effectively created directly by the shock front without invoking microinstabilities. The analysis of both individual and statistical ion trajectories evidences that: (i) two new parameters, namely the interaction time DT_inter and distance of penetration L_depth into the shock wave, play a key role and allow to discriminate these two populations. "GPB" population is characterized by a very short interaction time (DT_inter = 1 to 2 Tci) in comparison to the "FAB" population (DT_inter = 2 Tci to 10 Tci) which moves back and forth between the upstream edge of the shock front and the overshoot, where tci is the upstream ion gyroperiod. (ii) the importance of the injection angle (i.e. the angle between the normal of the shock front and the gyration velocity when ions reach the shock) to understand how the reflection process takes place. (iii) "FAB" population drifts along the curved shock front scanning a large Theta_Bn range from 90°. (iv) "GPB" population is embedded within the "FAB" population near the shock front which explains the difficulty to identify such a population in the experimental
Wave intensity analysis of left atrial mechanics and energetics in anesthetized dogs.
Hobson, Tracy N; Flewitt, Jacqueline A; Belenkie, Israel; Tyberg, John V
2007-03-01
The left atrium (LA) acts as a booster pump during late diastole, generating the Doppler transmitral A wave and contributing incrementally to left ventricular (LV) filling. However, after volume loading and in certain disease states, LA contraction fills the LV less effectively, and retrograde flow (i.e., the Doppler Ar wave) into the pulmonary veins increases. The purpose of this study was to provide an energetic analysis of LA contraction to clarify the mechanisms responsible for changes in forward and backward flow. Wave intensity analysis was performed at the mitral valve and a pulmonary vein orifice. As operative LV stiffness increased with progressive volume loading, the reflection coefficient (i.e., energy of reflected wave/energy of incident wave) also increased. This reflected wave decelerated the forward movement of blood through the mitral valve and was transmitted through the LA, accelerating retrograde blood flow in the pulmonary veins. Although total LA work increased with volume loading, the forward hydraulic work decreased and backward hydraulic work increased. Thus wave reflection due to increased LV stiffness accounts for the decrease in the A wave and the increase in the Ar wave measured by Doppler.
NASA Astrophysics Data System (ADS)
Heinz-Essen, H.; Grevemeyer, Ingo; Herber, Rolf; Weigel, Wilfried
1998-01-01
An experiment with a newly developed implosive source, located about 1 m above the seafloor at 3665 m depth, revealed a slow interface wave. This wave is attributed to S waves in a soft sediment layer covering the hard rock sub-bottom. Dispersion analysis by means of the multiple-filter technique yields the group velocity as a function of frequency. Model calculations showed that the observed dispersion curve can be reproduced by considering a steep gradient of S velocity within the sediment layer. Nearly perfect agreement of experimental and model data could be achieved with a sediment layer thickness of 21.5 m, an S speed of 225 m s- 1 at the water-sediment interface and an increase by 23 s- 1 within the layer. These values are relatively high compared to data from the literature. However, previous estimates of in situ S-wave velocity have been obtained on old oceanic crust in the vicinity of continents or islands, while our experiment was carried out on young Pacific crust. Therefore, we suggest two mechanisms which could support a relatively high S speed in sediments: (1) the input of hydrothermally generated metalliferous sediments from the adjacent spreading axis; and (2) post-depositional diagenesis which has accelerated the induration of sediments.
Distinguishing signal from noise: New techniques for gravitational wave data analysis
NASA Astrophysics Data System (ADS)
Baker, Paul Thomas
The principal problem of gravitational wave detection is distinguishing true gravitational wave signals from non-Gaussian noise artifacts. We describe two methods to deal with the problem of non-Gaussian noise in the Laser Interferometer Gravitational Observatory (LIGO). Perturbed black holes (BH) are known to vibrate at determinable quasi-normal mode frequencies. These vibrational modes are strongly excited during the inspiral and merger of binary BH systems. We will develop a template based search for gravitational waves from black hole ringdowns: the final stage of binary merger. Past searches for gravitational waves developed ad hoc detection statistics in an attempt to separate the expected gravitational wave signals from noise. We show how using the output of a multi-variate statistical classifier trained to directly probe the high dimensional parameter space of gravitational waves can improve a search over more traditional means. We conclude by placing preliminary upper limits on the rate of ringdown producing binary BH mergers. LIGO data contains frequent, non-Gaussian, instrument artifacts or glitches. Current LIGO searches for un-modeled gravitational wave bursts are primarily limited by the presence of glitches in analyzed data. We describe the BayesWave algorithm, wherein we model gravitational wave signals and detector glitches simultaneously in the wavelet domain. Using bayesian model selection techniques and a reversible jump Markov chain Monte Carlo, we are able determine whether data is consistent with the presence of gravitational waves, detector glitches, or both. We demonstrate BayesWave's utility as a data quality tool by fitting glitches non-Gaussian LIGO data. Finally, we discuss how BayesWave can be extended into a full-fledged search for gravitational wave bursts.
NASA Astrophysics Data System (ADS)
Hou, Zhen-Long; Wei, Xiao-Hui; Huang, Da-Nian; Sun, Xu
2015-09-01
We apply reweighted inversion focusing to full tensor gravity gradiometry data using message-passing interface (MPI) and compute unified device architecture (CUDA) parallel computing algorithms, and then combine MPI with CUDA to formulate a hybrid algorithm. Parallel computing performance metrics are introduced to analyze and compare the performance of the algorithms. We summarize the rules for the performance evaluation of parallel algorithms. We use model and real data from the Vinton salt dome to test the algorithms. We find good match between model and real density data, and verify the high efficiency and feasibility of parallel computing algorithms in the inversion of full tensor gravity gradiometry data.
FFT and Wavelet analysis for the study of gravity wave activity over a modeled hurricane environment
NASA Astrophysics Data System (ADS)
Kuester, M. A.; Alexander, J.; Ray, E.
2005-12-01
Understanding of gravity waves and their sources are important for driving global circulations in climate and weather forecasting models. Temperature fluctuations associated with gravity waves near the tropopause also affect cirrus cloud formation, which is important to the study of radiative forcing in the atmosphere. Deep convection is believed to be a major source for these waves and hurricanes may be particularly long-lived and intense sources. Simulations of Hurricane Humberto have been studied using the Pennsylvania State University-National Center for Atmospheric Research (PSU-NCAR) fifth-generation Mesoscale Model (MM5). Humberto is simulated at both tropical storm and hurricane stages. Information about gravity waves and their sources can be inferred from horizontal wind and temperature variances in the troposphere and lower stratosphere. Both Fast Fourier Transform (FFT) and Wavelet analyses are employed to investigate wave properties and behavior in the lower stratosphere. FFT analysis gives an overall view of storm affects while Wavelet analysis gives a local picture of gravity wave activity. It is found that a hurricane can be a significant source of deep heating which actively triggers gravity waves from the hot tower region of the storm eye wall. Convectively generated gravity waves are observed in the lower stratosphere of this model with horizontal scales of 10-250 km, vertical scales around 5 km and with intrinsic periods of approximately 20 minutes. Some specific characteristics of gravity waves found above the storm will be presented along with further discussion from the wave activity observed with the model. Deep convection over the oceans is thought to play a key role in atmospheric forcing via the creation of vertically propagating gravity waves and hurricane induced gravity waves may play a role in stratospheric forcing during the hurricane season.
Comparison of Test and Finite Element Analysis for Two Full-Scale Helicopter Crash Tests
NASA Technical Reports Server (NTRS)
Annett, Martin S.; Horta,Lucas G.
2011-01-01
Finite element analyses have been performed for two full-scale crash tests of an MD-500 helicopter. The first crash test was conducted to evaluate the performance of a composite deployable energy absorber under combined flight loads. In the second crash test, the energy absorber was removed to establish the baseline loads. The use of an energy absorbing device reduced the impact acceleration levels by a factor of three. Accelerations and kinematic data collected from the crash tests were compared to analytical results. Details of the full-scale crash tests and development of the system-integrated finite element model are briefly described along with direct comparisons of acceleration magnitudes and durations for the first full-scale crash test. Because load levels were significantly different between tests, models developed for the purposes of predicting the overall system response with external energy absorbers were not adequate under more severe conditions seen in the second crash test. Relative error comparisons were inadequate to guide model calibration. A newly developed model calibration approach that includes uncertainty estimation, parameter sensitivity, impact shape orthogonality, and numerical optimization was used for the second full-scale crash test. The calibrated parameter set reduced 2-norm prediction error by 51% but did not improve impact shape orthogonality.
Analysis of High Temperature Reactor Control Rod Worth for the Initial and Full Core
NASA Astrophysics Data System (ADS)
Oktajianto, Hammam; Setiawati, Evi; Anam, Khoirul; Sugito, Heri
2017-01-01
Control rod is one important component in a nuclear reactor. In nuclear reactor operations the control rod functions to shut down the reactor. This research analyses ten control rods worth of HTR (High Temperature Reactor) at initial and full core. The HTR in this research adopts HTR-10 China and HTR- of pebble bed. Core calculations are performed by using MCNPX code after modelling the entire parts of core in condition of ten control rods fully withdrawn, all control rods in with 20 cm ranges of depth and the use of one control rod. Pebble bed and moderator balls are distributed in the core zone using a Body Centred Cubic (BCC) lattice by ratio of 57:43. The research results are obtained that the use of one control rod will decrease the reactor criticality of 2.04±0.12 %Δk/k at initial core and 1.57±0.10 %Δk/k at full core. The deeper control rods are in, the lesser criticality of reactor is with reactivity of ten control rods of 16.41±0.11 %Δk/k at initial core and 15.43±0.11 %Δk/k at full core. The results show that the use of ten control rods at full core will keep achieving subcritical condition even though the reactivity is smaller than reactivity at initial core.
Rayleigh waves ellipticity and mode mis-identificationin multi-channel analysis of surface waves
NASA Astrophysics Data System (ADS)
Boaga, J.; Cassiani, G.; Strobbia, C. L.; Vignoli, G.
2012-12-01
The Surface Wave Method is a popular tool for geotechnical characterization since it supplies a cost effective testing procedure capable of retrieving the shear wave velocity structure of the near surface. Several acquisition and processing approaches have been developed to infer the Rayleigh wave dispersion curve which is then inverted. Typically, single component vertical and multi channel receivers are used. In most cases the inversion of the dispersion properties is carried out assuming that the experimental dispersion curve corresponds to a single mode, mostly the fundamental Rayleigh mode, unless clear evidence dictates the existence of a more complex response, e,g. in presence of low velocity layers and inversely dispersive sites. A correct identification of the modes is essential to avoid serious misinterpretation of the subsoil model. Here we consider the typical case of higher mode mis-identification known as 'osculation' ('kissing'). In general it is called 'osculation point' the point where the energy peak shifts at low frequencies from the fundamental to the first higher mode. This jump occurs, with a continuous smooth transition, around a well-define frequency where the two modes get very close to each other reaching similar Rayleigh velocity. It is known 'osculation' happens generally in presence of strong velocity contrasts, typically with a fast bedrock underlying loose sediments. The practical limitations of the acquired data affect the spectral and modal resolution, making it often impossible to identify the presence of more than one mode. In some cases, modes have a common root and cannot be separated at the osculation point. In such cases, mode misidentification can create a large overestimation of the bedrock velocity and a large error on its depth. In this work we examine the subsoil conditions that can generate this unwanted condition, and the common field acquisition procedures that can contribute to producing data having such deceptive
Computational analysis of compaction wave dissipation in porous metalized explosives
NASA Astrophysics Data System (ADS)
Rao, Pratap; Gonthier, Keith A.
2014-05-01
It is well established that the inclusion of reactive metals in explosive formulations can enhance post-detonation energy release but it remains unclear, even for idealized systems, how the composition and microstructure of metal containing porous solid explosives affects dissipative heating within compaction waves that is important for weak initiation of detonation. In this study, we perform inert meso-scale simulations to computationally examine how the initial porosity and metal mass fraction of aluminized HMX influences dissipation within compaction waves and we compare predictions to those given by a macro-scale compaction theory. The meso-scale model uses a hyperthermoelastic-viscoplastic and stick-slip friction theory to track the evolution of thermomechanical fields within individual particles that result from pore collapse within waves. Effective quasi-steady wave profiles are obtained by averaging meso-scale fields over space and time. The macro-scale theory predicts the variation in effective thermomechanical fields within waves due to imbalances in the phase-specific pressures and configurational stresses. Qualitative agreement exists between meso-scale and macro-scale predictions.
Causal diagrams and multivariate analysis I: a quiver full of arrows.
Jupiter, Daniel C
2014-01-01
How do we know which variables we should include in our multivariate analyses? What role does each variable play in our understanding of the analysis? In this article I begin a discussion of these issues and describe 2 different types of studies for which this problem must be handled in different ways.
Full potential methods for analysis/design of complex aerospace configurations
NASA Technical Reports Server (NTRS)
Shankar, Vijaya; Szema, Kuo-Yen; Bonner, Ellwood
1986-01-01
The steady form of the full potential equation, in conservative form, is employed to analyze and design a wide variety of complex aerodynamic shapes. The nonlinear method is based on the theory of characteristic signal propagation coupled with novel flux biasing concepts and body-fitted mapping procedures. The resulting codes are vectorized for the CRAY XMP and the VPS-32 supercomputers. Use of the full potential nonlinear theory is demonstrated for a single-point supersonic wing design and a multipoint design for transonic maneuver/supersonic cruise/maneuver conditions. Achievement of high aerodynamic efficiency through numerical design is verified by wind tunnel tests. Other studies reported include analyses of a canard/wing/nacelle fighter geometry.
Full-thickness tears of the supraspinatus tendon: A three-dimensional finite element analysis.
Quental, C; Folgado, J; Monteiro, J; Sarmento, M
2016-12-08
Knowledge regarding the likelihood of propagation of supraspinatus tears is important to allow an early identification of patients for whom a conservative treatment is more likely to fail, and consequently, to improve their clinical outcome. The aim of this study was to investigate the potential for propagation of posterior, central, and anterior full-thickness tears of different sizes using the finite element method. A three-dimensional finite element model of the supraspinatus tendon was generated from the Visible Human Project data. The mechanical behaviour of the tendon was fitted from experimental data using a transversely isotropic hyperelastic constitutive model. The full-thickness tears were simulated at the supraspinatus tendon insertion by decreasing the interface area. Tear sizes from 10% to 90%, in 10% increments, of the anteroposterior length of the supraspinatus footprint were considered in the posterior, central, and anterior regions of the tendon. For each tear, three finite element analyses were performed for a supraspinatus force of 100N, 200N, and 400N. Considering a correlation between tendon strain and the risk of tear propagation, the simulated tears were compared qualitatively and quantitatively by evaluating the volume of tendon for which a maximum strain criterion was not satisfied. The finite element analyses showed a significant impact of tear size and location not only on the magnitude, but also on the patterns of the maximum principal strains. The mechanical outcome of the anterior full-thickness tears was consistently, and significantly, more severe than that of the central or posterior full-thickness tears, which suggests that the anterior tears are at greater risk of propagating than the central or posterior tears.
Computational analysis of full-length mouse cDNAs compared with human genome sequences.
Kondo, S; Shinagawa, A; Saito, T; Kiyosawa, H; Yamanaka, I; Aizawa, K; Fukuda, S; Hara, A; Itoh, M; Kawai, J; Shibata, K; Hayashizaki, Y
2001-09-01
Although the sequencing of the human genome is complete, identification of encoded genes and determination of their structures remain a major challenge. In this report, we introduce a method that effectively uses full-length mouse cDNAs to complement efforts in carrying out these difficult tasks. A total of 61,227 RIKEN mouse cDNAs (21,076 full-length and 40,151 EST sequences containing certain redundancies) were aligned with the draft human sequences. We found 35,141 non-redundant genomic regions that showed a significant alignment with the mouse cDNAs. We analyzed the structures and compositional properties of the regions detected by the full-length cDNAs, including cross-species comparisons, and noted a systematic bias of GENSCAN against exons of small size and/or low GC-content. Of the cDNAs locating the 35,141 genomic regions, 3,217 did not match any sequences of the known human genes or ESTs. Among those 3,217 cDNAs, 1,141 did not show any significant similarity to any protein sequence in the GenBank non-redundant protein database and thus are candidates for novel genes.
Factorized molecular wave functions: Analysis of the nuclear factor
Lefebvre, R.
2015-06-07
The exact factorization of molecular wave functions leads to nuclear factors which should be nodeless functions. We reconsider the case of vibrational perturbations in a diatomic species, a situation usually treated by combining Born-Oppenheimer products. It was shown [R. Lefebvre, J. Chem. Phys. 142, 074106 (2015)] that it is possible to derive, from the solutions of coupled equations, the form of the factorized function. By increasing artificially the interstate coupling in the usual approach, the adiabatic regime can be reached, whereby the wave function can be reduced to a single product. The nuclear factor of this product is determined by the lowest of the two potentials obtained by diagonalization of the potential matrix. By comparison with the nuclear wave function of the factorized scheme, it is shown that by a simple rectification, an agreement is obtained between the modified nodeless function and that of the adiabatic scheme.
An Analysis of Wave Interactions in Swept-Wing Flows
NASA Technical Reports Server (NTRS)
Reed, H. L.
1984-01-01
Crossflow instabilities dominate disturbance growth in the leading-edge region of swept wings. Streamwise vortices in a boundary layer strongly influence the behavior of other disturbances. Amplification of crossflow vortices near the leading edge produces a residual spanwise nonuniformity in the mid-chord regions where Tollmien-Schlichting (T-S) waves are strongly amplified. Should the T-S wave undergo double-exponential growth because of this effect, the usual transition prediction methods would fail. The crossflow/Tollmien-Schlichting wave interaction was modeled as a secondary instability. The effects of suction are included, and different stability criteria are examined. The results are applied to laminar flow control wings characteristic of energy-efficient aircraft designs.
NASA Technical Reports Server (NTRS)
Hofman, L. B.; Erickson, W. K.; Donovan, W. E.
1984-01-01
Image Display and Analysis Systems (MIDAS) developed at NASA/Ames for the analysis of Landsat MSS images is described. The MIDAS computer power and memory, graphics, resource-sharing, expansion and upgrade, environment and maintenance, and software/user-interface requirements are outlined; the implementation hardware (including 32-bit microprocessor, 512K error-correcting RAM, 70 or 140-Mbyte formatted disk drive, 512 x 512 x 24 color frame buffer, and local-area-network transceiver) and applications software (ELAS, CIE, and P-EDITOR) are characterized; and implementation problems, performance data, and costs are examined. Planned improvements in MIDAS hardware and design goals and areas of exploration for MIDAS software are discussed.
2007-12-01
and technical guidance were provided by Dr. Reed B. Freeman, Dr. Donald M. Smith, Dr. J . Kent Newman, Louis W. Mason, and Quint Mason of APB; Harold...T. Carr of the ERDC Information Technology Laboratory; and Dennis Beausoliel and Charles J . Wilson of the ERDC Directorate of Public Works. The...theories of layered elastic analysis are credited to V. J . Boussinesq who published the work in 1885. Many variations have come about using the
Getting full control of canonical correlation analysis with the AutoBiplot.CCA function
NASA Astrophysics Data System (ADS)
Alves, M. Rui
2016-06-01
Function AutoBiplot.CCA was built in R language. Given two multivariate data sets, this function carries out a conventional canonical correlation analysis, followed by the automatic production of predictive biplots based on the accuracy of readings as assessed by a mean standard predictive error and a user defined tolerance value. As the user's intervention is mainly restricted to the choice of the magnitude of the t.axis value, common misinterpretations, overestimations and adjustments between outputs and personal beliefs are avoided.
2005-03-01
picture at 22/00Z.............50 x Figure 24. Case 5 – wave parameters........................51 Figure 25. Evolution of energy density (arrow...equation or energy balance equation: . in nl ds F v F S S S S t ∂ + ∇ = ≡ + + ∂ r (1) where ( , ; , )F f x tθ r is the two dimensional...collected from an offshore directional Seawatch buoy, in the vicinity of Cape Silleiro, Rayo Silleiro 19 (“E1”), (Figure 3), was provided by the
Ivanov, J.; Miller, R.D.; Xia, J.; Steeples, D.; Park, C.B.
2006-01-01
We describe a possible solution to the inverse refraction-traveltime problem (IRTP) that reduces the range of possible solutions (nonuniqueness). This approach uses a reference model, derived from surface-wave shear-wave velocity estimates, as a constraint. The application of the joint analysis of refractions with surface waves (JARS) method provided a more realistic solution than the conventional refraction/tomography methods, which did not benefit from a reference model derived from real data. This confirmed our conclusion that the proposed method is an advancement in the IRTP analysis. The unique basic principles of the JARS method might be applicable to other inverse geophysical problems. ?? 2006 Society of Exploration Geophysicists.
Asymptotic analysis of dissipative waves with applications to their numerical simulation
NASA Technical Reports Server (NTRS)
Hagstrom, Thomas
1990-01-01
Various problems involving the interplay of asymptotics and numerics in the analysis of wave propagation in dissipative systems are studied. A general approach to the asymptotic analysis of linear, dissipative waves is developed. It was applied to the derivation of asymptotic boundary conditions for numerical solutions on unbounded domains. Applications include the Navier-Stokes equations. Multidimensional traveling wave solutions to reaction-diffusion equations are also considered. A preliminary numerical investigation of a thermo-diffusive model of flame propagation in a channel with heat loss at the walls is presented.
Pedigree analysis: One teaching strategy to incorporate genetics into a full FNP program.
Schumacher, Gretchen; Conway, Alice E; Sparlin, Judith A
2006-05-01
The successful completion of the genome project in April 2003 and explosion of genetic knowledge is impacting healthcare at a dramatic rate. All healthcare providers need to update themselves on genetics in order to provide comprehensive care. This article describes a national grant obtained to educate faculty regarding incorporating genetics into courses. It also presents an innovate method for incorporating genetics into a full Family Nurse Practitioner (FNP) curriculum. Student responses and guidelines for one assignment are included. Utilizing this type of assignment in FNP courses is beneficial to both students and faculty. With more FNPs assessing patterns for illness in families, primary prevention and earlier intervention in primary care can be achieved.
Full 3D Analysis of the GE90 Turbofan Primary Flowpath
NASA Technical Reports Server (NTRS)
Turner, Mark G.
2000-01-01
The multistage simulations of the GE90 turbofan primary flowpath components have been performed. The multistage CFD code, APNASA, has been used to analyze the fan, fan OGV and booster, the 10-stage high-pressure compressor and the entire turbine system of the GE90 turbofan engine. The code has two levels of parallel, and for the 18 blade row full turbine simulation has 87.3 percent parallel efficiency with 121 processors on an SGI ORIGIN. Grid generation is accomplished with the multistage Average Passage Grid Generator, APG. Results for each component are shown which compare favorably with test data.
Resolution analysis of marine seismic full waveform data by Bayesian inversion
NASA Astrophysics Data System (ADS)
Ray, A.; Sekar, A.; Hoversten, G. M.; Albertin, U.
2015-12-01
The Bayesian posterior density function (PDF) of earth models that fit full waveform seismic data convey information on the uncertainty with which the elastic model parameters are resolved. In this work, we apply the trans-dimensional reversible jump Markov Chain Monte Carlo method (RJ-MCMC) for the 1D inversion of noisy synthetic full-waveform seismic data in the frequency-wavenumber domain. While seismic full waveform inversion (FWI) is a powerful method for characterizing subsurface elastic parameters, the uncertainty in the inverted models has remained poorly known, if at all and is highly initial model dependent. The Bayesian method we use is trans-dimensional in that the number of model layers is not fixed, and flexible such that the layer boundaries are free to move around. The resulting parameterization does not require regularization to stabilize the inversion. Depth resolution is traded off with the number of layers, providing an estimate of uncertainty in elastic parameters (compressional and shear velocities Vp and Vs as well as density) with depth. We find that in the absence of additional constraints, Bayesian inversion can result in a wide range of posterior PDFs on Vp, Vs and density. These PDFs range from being clustered around the true model, to those that contain little resolution of any particular features other than those in the near surface, depending on the particular data and target geometry. We present results for a suite of different frequencies and offset ranges, examining the differences in the posterior model densities thus derived. Though these results are for a 1D earth, they are applicable to areas with simple, layered geology and provide valuable insight into the resolving capabilities of FWI, as well as highlight the challenges in solving a highly non-linear problem. The RJ-MCMC method also presents a tantalizing possibility for extension to 2D and 3D Bayesian inversion of full waveform seismic data in the future, as it objectively
NASA Astrophysics Data System (ADS)
Krueger, Ronald R.; Juhasz, Tibor
1995-05-01
With the event of topographic steep central islands following excimer laser surgery and the potential damage to the corneal endothelium, shock waves are playing an increasingly important role in laser refractive surgery. With this in mind, we performed a comparative shock wave analysis in corneal tissue using an excimer laser, picosecond laser, and femtosecond laser. We used a Lambda Physik excimer laser at 308 nm wavelength, a Nd:YLF picosecond laser at 1053 nm wavelength and a synchronously pumped linear cavity femtosecond laser at 630 nm wavelength. The pulse widths of the corresponding lasers were 8 ns, 18 ps, 150 fs, respectively. The energy density of irradiation was 2.5 to 8 times the threshold level being 2 J/cm2 (excimer laser), 86 J/cm2 (picosecond laser) and 10.3 J/cm2 (femtosecond laser). Shock wave dynamics were analyzed using time-resolved photography on a nanosecond time scale using the picosecond laser in corneal tissue, water and air. Shock wave dynamics using the femtosecond laser were studied in water only while the excimer laser induced shock wave during corneal ablation was studied in air only. We found the dynamics of shock waves to be similar in water and corneal tissue indicating that water is a good model to investigate shock wave effects in the cornea. The magnitude of the shock wave velocity and pressure decays over time to that of a sound wave. The distance over which it decays is 3 mm in air with the excimer laser and 600 - 700 micrometers in air with the picosecond laser. In water, the picosecond laser shock wave decays over a distance of 150 micrometers compared to the femtosecond laser shock wave which decays over a distance of 30 micrometers . Overall the excimer laser shock wave propagates 5 times further than that of the picosecond laser and the picosecond laser shock wave propagates 5 times further than that of the femtosecond laser. In this preliminary comparison, the time and distance for shock wave decay appears to be directly
Huettig, Fabian; Axmann, Detlef
2014-01-01
AIM: To identify standards, how entities of dental status are assessed and reported from full-arch radiographs of adults. METHODS: A PubMed (Medline) search was performed in November 2011. Literature had to report at least one out of four defined entities using radiographs: number of teeth or implants; caries, fillings or restorations; root-canal fillings and apical health; alveolar bone level. Cohorts included to the study had to be of adult age. Methods of radiographic assessment were noted and checked for the later mode of report in text, tables or diagrams. For comparability, the encountered mode of report was operationalized to a logical expression. RESULTS: Thirty-seven out of 199 articles were evaluated via full-text review. Only one article reported all four entities. Eight articles reported at the maximum 3 comparable entities. However, comparability is impeded because of the usage of absolute or relative frequency, mean or median values as well as grouping. Furthermore the methods of assessment were different or not described sufficiently. Consequently, established sum scores turned out to be highly questionable, too. The amount of missing data within all studies remained unclear. It is even so remissed to mention supernumerary and aplased teeth as well as the count of third molars. CONCLUSION: Data about dental findings from radiographs is, if at all possible, only comparable with serious limitations. A standardization of both, assessing and reporting entities of dental status from radiographs is missing and has to be established within a report guideline. PMID:25325067
LS-DYNA Analysis of a Full-Scale Helicopter Crash Test
NASA Technical Reports Server (NTRS)
Annett, Martin S.
2010-01-01
A full-scale crash test of an MD-500 helicopter was conducted in December 2009 at NASA Langley's Landing and Impact Research facility (LandIR). The MD-500 helicopter was fitted with a composite honeycomb Deployable Energy Absorber (DEA) and tested under vertical and horizontal impact velocities of 26 ft/sec and 40 ft/sec, respectively. The objectives of the test were to evaluate the performance of the DEA concept under realistic crash conditions and to generate test data for validation of a system integrated LS-DYNA finite element model. In preparation for the full-scale crash test, a series of sub-scale and MD-500 mass simulator tests was conducted to evaluate the impact performances of various components, including a new crush tube and the DEA blocks. Parameters defined within the system integrated finite element model were determined from these tests. The objective of this paper is to summarize the finite element models developed and analyses performed, beginning with pre-test and continuing through post test validation.
Determination of microseismic event azimuth from S-wave splitting analysis
NASA Astrophysics Data System (ADS)
Yuan, Duo; Li, Aibing
2017-02-01
P-wave hodogram analysis has been the only reliable method to obtain microseismic event azimuths for one-well monitoring. However, microseismic data usually have weak or even no P-waves due to near double-couple focal mechanisms and limited ray path coverage, which causes large uncertainties in determined azimuths and event locations. To solve this problem, we take advantage of S-waves, which are often much stronger than P waves in microseismic data, and determine event azimuths by analyzing S-wave splitting data. This approach utilizes the positive correlation between the accuracy of event azimuth and the effectiveness of measuring S-wave splitting parameters and finds the optimal azimuth through a grid search. We have demonstrated that event azimuths can be well constrained from S-wave splitting analysis using both synthetic and field microseismic data. This method is less sensitive to noise than the routine P-wave hodogram method and provides a new way of determining microseismic event azimuths.
Standing Waves in an Elastic Spring: A Systematic Study by Video Analysis
NASA Astrophysics Data System (ADS)
Ventura, Daniel Rodrigues; de Carvalho, Paulo Simeão; Dias, Marco Adriano
2017-04-01
The word "wave" 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, waves are oscillating variations of a physical quantity that involve the transfer of energy from one point to another, without displacement of matter. A wave can be formed by an elastic deformation, a variation of pressure, changes in the intensity of electric or magnetic fields, a propagation of a temperature variation, or other disturbances. Moreover, a wave can be categorized as pulsed or periodic. Most importantly, conditions can be set such that waves interfere with one another, resulting in standing waves. 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 wave propagation and the analysis of harmonics in standing waves.
NASA Astrophysics Data System (ADS)
Trupti, S.; Srinivas, K. N. S. S. S.; Pavan Kishore, P.; Seshunarayana, T.
2012-04-01
Multichannel analysis of surface waves (MASW) technique was employed for site characterization studies at the identified lineament locations along coastal regions of Andhra Pradesh covering ~ 600 km to measure the shear wave velocity. The shear (S)-wave velocity of near surface materials (such as soil, rocks and pavement) and its effect on seismic wave propagation are of fundamental interest in many groundwater, engineering and environmental studies. Geologically, the study area comprises of Precambrian basement over which younger rocks commencing with Jurassic, Cretaceous, Tertiary and Quaternary have given rise to varying sequences in different parts. The study has been conducted along the lineaments and these were selected based on the analysis of IRS-1D LISS-IV satellite images and the field geological investigation. The average shear wave velocity, stiffness and the liquefaction potential were evaluated by using the obtained shear wave velocities. Soils are classified into four categories as soft soils, stiff soils, dense soils/soft rock and hard rock based on the obtained shear wave velocities. The factor of safety (FS) against liquefaction is determined and it is found that the sites with low shear wave velocity have FS < 1 and these are possible liquefiable zones. The results of this study are useful to study the earthquake hazard assessment, and also taking the necessary precautions in the vicinity of the faults/lineaments for the construction of engineering projects such as pipelines, dams, bridges, canal alignments, and cross-drainage structures.
Energy Sources and Systems Analysis: 40 South Lincoln Redevelopment District (Full Report)
Not Available
2011-08-01
This report presents the results of a case study to analyze district energy systems for their potential use in a project that involves redeveloping 270 units of existing public housing, along with other nearby sites. When complete, the redevelopment project will encompass more than 900 mixed-income residential units, commercial and retail properties, and open space. The analysis estimated the hourly heating, cooling, domestic hot water, and electric loads required by the community; investigated potential district system technologies to meet those needs; and researched available fuel sources to power such systems.
Full phase analysis of portland clinker by penetrating synchrotron powder diffraction.
de la Torre, A G; Cabeza, A; Calvente, A; Bruque, S; Aranda, M A
2001-01-15
Fabrication of portland cements commonly depends on X-ray fluorescence (XRF), which measures the elemental compositions. XRF is used to adjust the raw material proportions and to control the process conditions. However, to predict the mechanical strength of the resulting concrete, it is essential to know the phase composition which is, so far, indirectly inferred by the Bogue method. Here, we report a phase analysis of an industrial portland clinker containing six crystalline phases, Ca3SiO5, Ca2SiO4, Ca4Al2Fe2O10, Ca3Al2O6, NaK3(SO4)2, and CaO, by Rietveld refinement of synchrotron X-ray powder diffraction data (lambda = 0.442377 A). Even the minor component, CaO 0.45(2)%, was readily analyzed. We have also carried out a phase study of the same clinker with laboratory X-rays to characterize the changes in the detection limit and errors. Furthermore, by adding a suitable crystalline standard to the same clinker, we have determined the overall amorphous phase content. The procedure established for this state-of-the-art phase analysis shows the high precision that can be achieved by using penetrating X-rays, which is of interest not only in cement chemistry but in other industrially important multiphase systems such as slags, superalloys, or catalysts.
Analysis and Prediction of Ice Shedding for a Full-Scale Heated Tail Rotor
NASA Technical Reports Server (NTRS)
Kreeger, Richard E.; Work, Andrew; Douglass, Rebekah; Gazella, Matthew; Koster, Zakery; Turk, Jodi
2016-01-01
When helicopters are to fly in icing conditions, it is necessary to consider the possibility of ice shed from the rotor blades. In 2013, a series of tests were conducted on a heated tail rotor at NASA Glenn's Icing Research Tunnel (IRT). The tests produced several shed events that were captured on camera. Three of these shed events were captured at a sufficiently high frame rate to obtain multiple images of the shed ice in flight that had a sufficiently long section of shed ice for analysis. Analysis of these shed events is presented and compared to an analytical Shedding Trajectory Model (STM). The STM is developed and assumes that the ice breaks off instantly as it reaches the end of the blade, while frictional and viscous forces are used as parameters to fit the STM. The trajectory of each shed is compared to that predicted by the STM, where the STM provides information of the shed group of ice as a whole. The limitations of the model's underlying assumptions are discussed in comparison to experimental shed events.
Analysis of Wave Fields induced by Offshore Pile Driving
NASA Astrophysics Data System (ADS)
Ruhnau, M.; Heitmann, K.; Lippert, T.; Lippert, S.; von Estorff, O.
2015-12-01
Impact pile driving is the common technique to install foundations for offshore wind turbines. With each hammer strike the steel pile - often exceeding 6 m in diameter and 80 m in length - radiates energy into the surrounding water and soil, until reaching its targeted penetration depth. Several European authorities introduced limitations regarding hydroacoustic emissions during the construction process to protect marine wildlife. Satisfying these regulations made the development and application of sound mitigation systems (e.g. bubble curtains or insulation screens) inevitable, which are commonly installed within the water column surrounding the pile or even the complete construction site. Last years' advances have led to a point, where the seismic energy tunneling the sound mitigation systems through the soil and radiating back towards the water column gains importance, as it confines the maximum achievable sound mitigation. From an engineering point of view, the challenge of deciding on an effective noise mitigation layout arises, which especially requires a good understanding of the soil-dependent wave field. From a geophysical point of view, the pile acts like a very unique line source, generating a characteristic wave field dominated by inclined wave fronts, diving as well as head waves. Monitoring the seismic arrivals while the pile penetration steadily increases enables to perform quasi-vertical seismic profiling. This work is based on datasets that have been collected within the frame of three comprehensive offshore measurement campaigns during pile driving and demonstrates the potential of seismic arrivals induced by pile driving for further soil characterization.
A numerical model for dynamic wave rotor analysis
NASA Technical Reports Server (NTRS)
Paxson, D. E.
1995-01-01
A numerical model has been developed which can predict the dynamic (and steady state) performance of a wave rotor, given the geometry and time dependent boundary conditions. The one-dimensional, perfect gas, CFD based code tracks the gasdynamics in each of the wave rotor passages as they rotate past the various ducts. The model can operate both on and off-design, allowing dynamic behavior to be studied throughout the operating range of the wave rotor. The model accounts for several major loss mechanisms including finite passage opening time, fluid friction, heat transfer to and from the passage walls, and leakage to and from the passage ends. In addition, it can calculate the amount of work transferred to and from the fluid when the flow in the ducts is not aligned with the passages such as occurs in off-design operation. Since it is one-dimensional, the model runs reasonably fast on a typical workstation. This paper will describe the model and present the results of some transient calculations for a conceptual four port wave rotor designed as a topping cycle for a small gas turbine engine.
Telschow, Kenneth Louis; Deason, Vance Albert; Mukdadi, O.; Datta, S. K.
2001-11-01
The elastic properties of many materials in sheet or plate form can be approximated with orthotropic symmetry. In many sheet material manufacturing industries (e.g., the paper industry), manufacturers desire knowledge of certain anisotropic elastic properties in the sheet for handling and quality issues. Ultrasonic wave propagation in plate materials forms a method to determine the anisotropic elastic properties in a nondestructive manner. This work explores exact and approximate analysis methods of ultrasonic guided wave propagation in thin layers, explicitly dealing with orthotropic symmetry and propagation off-axis with respect to the manufacturing direction. Recent advances in full-field ultrasonic imaging methods, based on dynamic holography, allow simultaneous measurement of the plate wave motion in all planar directions within a single image. Results from this laser ultrasonic imaging approach are presented that record the lowest anti-symmetric (flexural) mode wavefront in a single image without scanning. Specific numerical predictions for flexural wave propagation in two distinctly different types of paper are presented and compared with direct imaging measurements. Very good agreement is obtained for the lowest anti-symmetric plate mode using paper properties independently determined by a third party. Complete determination of the elastic modulus tensor for orthotropic layers requires measurement of other modes in addition to the lowest anti-symmetric. Theoretical predictions are presented for other guided wave modes [extensional (S), flexural (A), and shear-horizontal (SH)] in orthotropic plates with emphasis on propagation in all planar directions. It is shown that there are significant changes in the dispersion characterization of these modes at certain frequencies (including off-axis mode coupling) that can be exploited to measure additional in-plane elastic moduli of thin layers. At present, the sensitivity of the imaging measurement approach limits
Whang, Liang-Ming; Hu, Tai-Ho; Liu, Pao-Wen Grace; Hung, Yu-Ching; Fukushima, Toshikazu; Wu, Yi-Ju; Chang, Shao-Hsiung
2015-02-01
This study investigated methanogenic communities involved in degradation of tetramethylammonium hydroxide (TMAH) in three full-scale bioreactors treating TMAH-containing wastewater. Based on the results of terminal-restriction fragment-length polymorphism (T-RFLP) and quantitative PCR analyses targeting the methyl-coenzyme M reductase alpha subunit (mcrA) genes retrieved from three bioreactors, Methanomethylovorans and Methanosarcina were the dominant methanogens involved in the methanogenic degradation of TMAH in the bioreactors. Furthermore, batch experiments were conducted to evaluate mcrA messenger RNA (mRNA) expression during methanogenic TMAH degradation, and the results indicated that a higher level of TMAH favored mcrA mRNA expression by Methansarcina, while Methanomethylovorans could only express considerable amount of mcrA mRNA at a lower level of TMAH. These results suggest that Methansarcina is responsible for methanogenic TMAH degradation at higher TMAH concentrations, while Methanomethylovorans may be important at a lower TMAH condition.
Analysis of in-core coolant temperatures of FFTF instrumented fuels tests at full power
Hoth, C.W
1981-01-01
Two full size highly instrumented fuel assemblies were inserted into the core of the Fast Flux Test Facility in December of 1979. The major objectives of these instrumented tests are to provide verification of the FFTF core conditions and to characterize temperature patterns within FFTF driver fuel assemblies. A review is presented of the results obtained during the power ascents and during irradiation at a constant reactor power of 400 MWt. The results obtained from these instrumented tests verify the conservative nature of the design methods used to establish core conditions in FFTF. The success of these tests also demonstrates the ability to design, fabricate, install and irradiate complex, instrumented fuel tests in FFTF using commercially procured components.
Classification and analysis of human ovarian tissue using full field optical coherence tomography.
Nandy, Sreyankar; Sanders, Melinda; Zhu, Quing
2016-12-01
In this study, a full field optical coherence tomography (FFOCT) system was used to analyze and classify normal and malignant human ovarian tissue. 14 ovarian tissue samples (7 normal, 7 malignant) were imaged with the FFOCT system and five features were extracted by analyzing the normalized image histogram from 56 FFOCT images, based on the differences in the morphology of the normal and malignant tissue samples. A generalized linear model (GLM) classifier was trained using 36 images, and sensitivity of 95.3% and specificity of 91.1% was obtained. 20 images were used to test the model, and a sensitivity of 91.6% and specificity of 87.7% was obtained.
Classification and analysis of human ovarian tissue using full field optical coherence tomography
Nandy, Sreyankar; Sanders, Melinda; Zhu, Quing
2016-01-01
In this study, a full field optical coherence tomography (FFOCT) system was used to analyze and classify normal and malignant human ovarian tissue. 14 ovarian tissue samples (7 normal, 7 malignant) were imaged with the FFOCT system and five features were extracted by analyzing the normalized image histogram from 56 FFOCT images, based on the differences in the morphology of the normal and malignant tissue samples. A generalized linear model (GLM) classifier was trained using 36 images, and sensitivity of 95.3% and specificity of 91.1% was obtained. 20 images were used to test the model, and a sensitivity of 91.6% and specificity of 87.7% was obtained. PMID:28018734
An analysis of full-disk observations of facular contrast in the blue and red
NASA Astrophysics Data System (ADS)
Ahern, Sean; Chapman, G. A.
2000-01-01
Full-disk images from the Cartesian Full-Disk Telescope no. 2 (CFDT2) were used to study the center-to-limb (CLV) variation of facular contrast in two colors. The CFDT2 images, which have 2.5 arc sec pixels, were obtained during the summer months of 1993, 1994 and 1995. In order to minimize the bias in finding faint facular features in continuum images, we have used coaligned images obtained in the Ca K-line to identify faculae. Faculae were sorted into 20 annular bins of equal width. To reduce the effects of seeing, faculae were not identified closer to the limb than μ=0.2. The facular pixel contrasts were fitted to various trial functions. The contrast in the blue filter (470.6 nm) rose from 0.122% at disk center to 12.2% at μ=0.2. The contrast in the red filter (672.3 nm) rose from 0.13% at disk center to 8.16% at μ=0.2. We have also analyzed the facular contrasts multiplied by their μ-value to obtain an estimate of facular flux tube contrasts. These flux tube contrasts increased roughly linearly from μ=0.95 to 0.25. The blue flux tube contrast reached a maximum of 2.48% near μ=0.25. The red flux tube contrast reached a maximum of 1.59% at μ=0.2. These contrast values are not corrected for the filling factor. The blue curve leveled off slightly betwen μ=0.25 and 0.2 while the red curve showed no deviation from its linear trend. These results may provide some support for the hot wall model of facular flux tubes.
Kayen, Robert E.; Carkin, Bradley A.; Allen, Trevor; Collins, Clive; McPherson, Andrew; Minasian, Diane L.
2015-01-01
One-dimensional shear-wave 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 waves (SASW) method. The SASW method is a noninvasive method that indirectly estimates the VS at depth from variations in the Rayleigh wave phase velocity at the surface.
Analysis of full charge reconstruction algorithms for x-ray pixelated detectors
Baumbaugh, A.; Carini, G.; Deptuch, G.; Grybos, P.; Hoff, J.; Siddons, P., Maj.; Szczygiel, R.; Trimpl, M.; Yarema, R.; /Fermilab
2011-11-01
Existence of the natural diffusive spread of charge carriers on the course of their drift towards collecting electrodes in planar, segmented detectors results in a division of the original cloud of carriers between neighboring channels. This paper presents the analysis of algorithms, implementable with reasonable circuit resources, whose task is to prevent degradation of the detective quantum efficiency in highly granular, digital pixel detectors. The immediate motivation of the work is a photon science application requesting simultaneous timing spectroscopy and 2D position sensitivity. Leading edge discrimination, provided it can be freed from uncertainties associated with the charge sharing, is used for timing the events. Analyzed solutions can naturally be extended to the amplitude spectroscopy with pixel detectors.
Analysis of Full Charge Reconstruction Algorithms for X-Ray Pixelated Detectors
Baumbaugh, A.; Carini, G.; Deptuch, G.; Grybos, P.; Hoff, J.; Siddons, P., Maj.; Szczygiel, R.; Trimpl, M.; Yarema, R.; /Fermilab
2012-05-21
Existence of the natural diffusive spread of charge carriers on the course of their drift towards collecting electrodes in planar, segmented detectors results in a division of the original cloud of carriers between neighboring channels. This paper presents the analysis of algorithms, implementable with reasonable circuit resources, whose task is to prevent degradation of the detective quantum efficiency in highly granular, digital pixel detectors. The immediate motivation of the work is a photon science application requesting simultaneous timing spectroscopy and 2D position sensitivity. Leading edge discrimination, provided it can be freed from uncertainties associated with the charge sharing, is used for timing the events. Analyzed solutions can naturally be extended to the amplitude spectroscopy with pixel detectors.
NASA Astrophysics Data System (ADS)
Ma, Juan; Sahraee, Shahab; Wriggers, Peter; De Lorenzis, Laura
2015-05-01
In this work, stochastic homogenization analysis of heterogeneous materials is addressed in the context of elasticity under finite deformations. The randomness of the morphology and of the material properties of the constituents as well as the correlation among these random properties are fully accounted for, and random effective quantities such as tangent tensor, first Piola-Kirchhoff stress, and strain energy along with their numerical characteristics are tackled under different boundary conditions by a multiscale finite element strategy combined with the Montecarlo method. The size of the representative volume element (RVE) with randomly distributed particles for different particle volume fractions is first identified by a numerical convergence scheme. Then, different types of displacement-controlled boundary conditions are applied to the RVE while fully considering the uncertainty in the microstructure. The influence of different random cases including correlation on the random effective quantities is finally analyzed.
Garcia-Barrera, Ali A; Del Valle, Alberto; Montaño-Hirose, Juan A; Barrón, Blanca Lilia; Salinas-Trujano, Juana; Torres-Flores, Jesus
2017-02-09
We report the complete genome sequences of four neurovirulent isolates of porcine rubulavirus (PorPV) from 2015 and one historical PorPV isolate from 1984 obtained by next-generation sequencing. A phylogenetic tree constructed using the individual sequences of the complete HN genes of the 2015 isolates and other historical sequences deposited in the GenBank database revealed that several recent neurovirulent isolates of PorPV (2008-2015) cluster together in a separate clade. Phylogenetic analysis of the complete genome sequences revealed that the neurovirulent strains of PorPV that circulated in Mexico during 2015 are genetically different from the PorPV strains that circulated during the 1980s.
Loncoman, Carlos A; Vaz, Paola K; Coppo, Mauricio Jc; Hartley, Carol A; Morera, Francisco J; Browning, Glenn F; Devlin, Joanne M
2017-04-01
Recombination in alphaherpesviruses was first described more than sixty years ago. Since then, different techniques have been used to detect recombination in natural (field) and experimental settings. Over the last ten years, next-generation sequencing (NGS) technologies and bioinformatic analyses have greatly increased the accuracy of recombination detection, particularly in field settings, thus contributing greatly to the study of natural alphaherpesvirus recombination in both human and veterinary medicine. Such studies have highlighted the important role that natural recombination plays in the evolution of many alphaherpesviruses. These studies have also shown that recombination can be a safety concern for attenuated alphaherpesvirus vaccines, particularly in veterinary medicine where such vaccines are used extensively, but also potentially in human medicine where attenuated varicella zoster virus vaccines are in use. This review focuses on the contributions that NGS and sequence analysis have made over the last ten years to our understanding of recombination in mammalian and avian alphaherpesviruses, with particular focus on attenuated live vaccine use.
VFMA: Topographic Analysis of Sensitivity Data From Full-Field Static Perimetry
Weleber, Richard G.; Smith, Travis B.; Peters, Dawn; Chegarnov, Elvira N.; Gillespie, Scott P.; Francis, Peter J.; Gardiner, Stuart K.; Paetzold, Jens; Dietzsch, Janko; Schiefer, Ulrich; Johnson, Chris A.
2015-01-01
Purpose: To analyze static visual field sensitivity with topographic models of the hill of vision (HOV), and to characterize several visual function indices derived from the HOV volume. Methods: A software application, Visual Field Modeling and Analysis (VFMA), was developed for static perimetry data visualization and analysis. Three-dimensional HOV models were generated for 16 healthy subjects and 82 retinitis pigmentosa patients. Volumetric visual function indices, which are measures of quantity and comparable regardless of perimeter test pattern, were investigated. Cross-validation, reliability, and cross-sectional analyses were performed to assess this methodology and compare the volumetric indices to conventional mean sensitivity and mean deviation. Floor effects were evaluated by computer simulation. Results: Cross-validation yielded an overall R2 of 0.68 and index of agreement of 0.89, which were consistent among subject groups, indicating good accuracy. Volumetric and conventional indices were comparable in terms of test–retest variability and discriminability among subject groups. Simulated floor effects did not negatively impact the repeatability of any index, but large floor changes altered the discriminability for regional volumetric indices. Conclusions: VFMA is an effective tool for clinical and research analyses of static perimetry data. Topographic models of the HOV aid the visualization of field defects, and topographically derived indices quantify the magnitude and extent of visual field sensitivity. Translational Relevance: VFMA assists with the interpretation of visual field data from any perimetric device and any test location pattern. Topographic models and volumetric indices are suitable for diagnosis, monitoring of field loss, patient counseling, and endpoints in therapeutic trials. PMID:25938002
Sensitivity of a numerical wave model on wind re-analysis datasets
NASA Astrophysics Data System (ADS)
Lavidas, George; Venugopal, Vengatesan; Friedrich, Daniel
2017-03-01
Wind is the dominant process for wave generation. Detailed evaluation of metocean conditions strengthens our understanding of issues concerning potential offshore applications. However, the scarcity of buoys and high cost of monitoring systems pose a barrier to properly defining offshore conditions. Through use of numerical wave models, metocean conditions can be hindcasted and forecasted providing reliable characterisations. This study reports the sensitivity of wind inputs on a numerical wave model for the Scottish region. Two re-analysis wind datasets with different spatio-temporal characteristics are used, the ERA-Interim Re-Analysis and the CFSR-NCEP Re-Analysis dataset. Different wind products alter results, affecting the accuracy obtained. The scope of this study is to assess different available wind databases and provide information concerning the most appropriate wind dataset for the specific region, based on temporal, spatial and geographic terms for wave modelling and offshore applications. Both wind input datasets delivered results from the numerical wave model with good correlation. Wave results by the 1-h dataset have higher peaks and lower biases, in expense of a high scatter index. On the other hand, the 6-h dataset has lower scatter but higher biases. The study shows how wind dataset affects the numerical wave modelling performance, and that depending on location and study needs, different wind inputs should be considered.
Aerodynamic analysis of three advanced configurations using the TranAir full-potential code
NASA Technical Reports Server (NTRS)
Madson, M. D.; Carmichael, R. L.; Mendoza, J. P.
1989-01-01
Computational results are presented for three advanced configurations: the F-16A with wing tip missiles and under wing fuel tanks, the Oblique Wing Research Aircraft, and an Advanced Turboprop research model. These results were generated by the latest version of the TranAir full potential code, which solves for transonic flow over complex configurations. TranAir embeds a surface paneled geometry definition in a uniform rectangular flow field grid, thus avoiding the use of surface conforming grids, and decoupling the grid generation process from the definition of the configuration. The new version of the code locally refines the uniform grid near the surface of the geometry, based on local panel size and/or user input. This method distributes the flow field grid points much more efficiently than the previous version of the code, which solved for a grid that was uniform everywhere in the flow field. TranAir results are presented for the three configurations and are compared with wind tunnel data.
High-density tiling microarray analysis of the full transcriptional activity of yeast.
David, Lior; Clauder-Münster, Sandra; Steinmetz, Lars M
2014-01-01
Understanding the relationship between DNA sequence variation and phenotypic variation in complex or quantitative traits is one of the major challenges in modern biology. We are witnessing a deluge of DNA sequence information and association studies of genetic polymorphisms with phenotypes of interest in families and populations. In addition, it has become clear that large portions of eukaryotic genomes beyond protein-coding genes are transcribed, generating numerous noncoding RNA (ncRNA) molecules whose functions remain mostly unknown.DNA oligonucleotide microarrays constitute a powerful technology for studying the expression of genes in different organisms. The Saccharomyces cerevisiae tiling array presents a significant advance over previous array-based platforms. It has a high density of overlapping probes that start on average every 8 bp along each strand of the genome, enabling precise definition of transcript structure. Furthermore, the array includes probes specific for the polymorphic positions of another, distantly related yeast strain, allowing accurate measurement of allele-specific expression in a hybrid of the two strains. This technology thus allows high-resolution, quantitative, strand- and allele-specific measurements of transcription from a full eukaryotic genome. In this chapter, we describe the methods for extracting RNA, synthesizing first-strand cDNA, fragmenting, and labeling of samples for hybridization to the tiling array. Combining genome-wide information on variation in DNA sequence with variation in transcript structure and levels promises to increase our understanding of the genotype-to-phenotype relationship.
An analysis of cardiac defects and surgical interventions in 84 cases with full trisomy 18.
Bruns, Deborah A; Martinez, Alyssa
2016-02-01
Trisomy 18 (Edwards syndrome) is the second most common autosomal trisomy after trisomy 21. Medical issues commonly include cardiac defects, such as ventricular septal defect (VSD) and atrial septal defect (ASD). If untreated, these conditions can contribute to the associated infant mortality. The objective of the study was review parent-reported information on 84 cases with full trisomy 18 focusing on prenatal and postnatal assessment and confirmation of cardiac defects and on subsequent treatment with cardiac surgery and post-surgery outcomes. At birth, 65 parent responses indicated the presence of VSD (77.4%), 38 ASD (45.2%), and 50 patent ductus arteriosus (PDA) (59.5%). The presence of multiple cardiac defects was also analyzed including 25 cases with VSD, ASD, and PDA at birth. The total reduced to 18 at survey completion. Twenty-four cases had one or more cardiac defects repaired for a total of 34 corrective surgeries. Age at surgery varied from 2 weeks to 41 months of age with most performed under 1 year of age. Twenty-one cases were still living at the time of survey completion (87.5%). From these date we provide recommendations and implications.
Full sky harmonic analysis hints at large ultra-high energy cosmic ray deflections
Tinyakov, P. G. Urban, F. R.
2015-03-15
The full-sky multipole coefficients of the ultra-high energy cosmic ray (UHECR) flux have been measured for the first time by the Pierre Auger and Telescope Array collaborations using a joint data set with E > 10 EeV. We calculate these harmonic coefficients in the model where UHECR are protons and sources trace the local matter distribution, and compare our results with observations. We find that the expected power for low multipoles (dipole and quadrupole, in particular) is sytematically higher than in the data: the observed flux is too isotropic. We then investigate to which degree our predictions are influenced by UHECR deflections in the regular Galactic magnetic field. It turns out that the UHECR power spectrum coefficients C{sub l} are quite insensitive to the effects of the Galactic magnetic field, so it is unlikely that the discordance can be reconciled by tuning the Galactic magnetic field model. On the contrary, a sizeable fraction of uniformly distributed flux (representing for instance an admixture of heavy nuclei with considerably larger deflections) can bring simulations and observations to an accord.
A Comparative Analysis of Two Full-Scale MD-500 Helicopter Crash Tests
NASA Technical Reports Server (NTRS)
Littell, Justin D.
2011-01-01
Two full scale crash tests were conducted on a small MD-500 helicopter at NASA Langley Research Center fs Landing and Impact Research Facility. One of the objectives of this test series was to compare airframe impact response and occupant injury data between a test which outfitted the airframe with an external composite passive energy absorbing honeycomb and a test which had no energy absorbing features. In both tests, the nominal impact velocity conditions were 7.92 m/sec (26 ft/sec) vertical and 12.2 m/sec (40 ft/sec) horizontal, and the test article weighed approximately 1315 kg (2900 lbs). Airframe instrumentation included accelerometers and strain gages. Four Anthropomorphic Test Devices were also onboard; three of which were standard Hybrid II and III, while the fourth was a specialized torso. The test which contained the energy absorbing honeycomb showed vertical impact acceleration loads of approximately 15 g, low risk for occupant injury probability, and minimal airframe damage. These results were contrasted with the test conducted without the energy absorbing honeycomb. The test results showed airframe accelerations of approximately 40 g in the vertical direction, high risk for injury probability in the occupants, and substantial airframe damage.
Wei, Dong; Yan, Tao; Zhang, Keyi; Chen, Ya; Wu, Na; Du, Bin; Wei, Qin
2017-02-28
In present study, two column-type sequencing batch reactors with alternative anoxic/aerobic phases were operated and compared under partial nitrification and full nitrification modes by controlling different dissolved oxygen (DO) conditions. During steady state, the characterizations of extracellular polymeric substances (EPS) from two reactors were qualitatively and quantitatively analyzed through chemical and spectroscopic approaches. Data implied that partial nitrification reactor had relatively higher total nitrogen (TN) removal efficiency and loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS) contents. According to excitation emission matrix (EEM) spectra, LB-EPS and TB-EPS from two kinds of reactors expressed similar fluorescence peak locations but different intensities. Fluorescence regional integration (FRI) further suggested that Region IV was the main fraction in both types of EPS fractions. Moreover, TB-EPS exhibited a greater number of molecular weight fractions than those of LB-EPS. Both EPS fractions had similar functional groups, which represented the complex nature of EPS compositions.
Simine, Lena; Segal, Dvira
2012-10-28
We study current-induced vibrational cooling, heating, and instability in a donor-acceptor rectifying molecular junction using a full counting statistics approach. In our model, electron-hole pair excitations are coupled to a given molecular vibrational mode which is either harmonic or highly anharmonic. This mode may be further coupled to a dissipative thermal environment. Adopting a master equation approach, we confirm the charge and heat exchange fluctuation theorem in the steady-state limit, for both harmonic and anharmonic models. Using simple analytical expressions, we calculate the charge current and several measures for the mode effective temperature. At low bias, we observe the effect of bias-induced cooling of the vibrational mode. At higher bias, the mode effective temperature is higher than the environmental temperature, yet the junction is stable. Beyond that, once the vibrational mode (bias-induced) excitation rate overcomes its relaxation rate, instability occurs. We identify regimes of instability as a function of voltage bias and coupling to an additional phononic thermal bath. Interestingly, we observe a reentrant behavior where an unstable junction can properly behave at a high enough bias. The mechanism for this behavior is discussed.
Analysis and Forecasting of Winds and Waves at Floating Type Wind Turbine Demonstration Site
NASA Astrophysics Data System (ADS)
Mase, Hajime; Yasuda, Tomohiro; Mori, Nobuhito; Tom, Tracey; Ikemoto, Ai; Utsunomiya, Tomoaki
2013-04-01
1. Introduction The floating type wind turbine demonstration project is being performed in Japan, and a 1:2 scale model was installed off the Kabashima Island in Nagasaki Prefecture on June 11th, 2012. As for the design, external forces such as wind and wave on the floating type wind turbine demonstration site were evaluated using various kinds of re-analysis and prediction data including NCEP wind data, JMA meteorological GPV data and NEDO data. Considerations for the design were given for wave characteristics of maximum and mean wave height, crest height, 2D height-period distribution, and wave energy spectrum. Tides, currents and winds were also evaluated. In addition the extreme wind speed was estimated including typhoon effects considering grid resolution dependence gust factor. A wind and wave prediction system was developed and its validity was examined by statistically comparing predicted values with measured data at the demonstration site. The present information system gives information for various user selected areas and lead times with both visual animations and time series graphs. 2. Design wave and wind The site is located off the Kabashima Island in Nagasaki Prefecture, Japan. Design forces were determined from extreme wind and wave statistics and an empirical method. The results are: 50 years return period wave and wind: Hs = 7.73 m, Ts = 14.0 s, U = 53.1 m/s 100 years return period wave and wind: Hs = 8.20 m, Ts = 14.3 m, U = 57.0 m/s Other characteristics were also determined, such as the maximum wave height, crest height, 2D height-period distribution and wave energy spectrum, tide, current and maximum wind. 3. Wind and wave prediction system The system composed of NCEP GFS (Global Forecasting System) meteorological data, down-scaling wind field by WRF (Weather Research Forecasting), JMA HAGPV (Hourly Analyzed Grid Point Value) 10m wind data, and wind-wave forecast data by SWAN (Simulating Waves Nearshore). The flowchart shown in Fig. 1 displays
Sequencing and annotated analysis of full genome of Holstein breed bull.
Kõks, Sulev; Reimann, Ene; Lilleoja, Rutt; Lättekivi, Freddy; Salumets, Andres; Reemann, Paula; Jaakma, Ülle
2014-08-01
In the present study, we describe the deep sequencing and structural analysis of the Holstein breed bull genome. Our aim was to receive a high-quality Holstein bull genome reference sequence and to describe different types of variations in its genome compared to Hereford breed as a reference. We generated four mate-paired libraries and one fragment library from 30 μg of genomic DNA. Colour space fasta were mapped and paired to the reference cow (Bos taurus) genome assembly from Oct. 2011 (Baylor 4.6.1/bosTau7). Initial sequencing resulted in the 4,864,054,296 of 50-bp reads. Average mapping efficiency was 71.7 % and altogether 3,494,534,136 reads and 157,928,163,086 bp were successfully mapped, resulting in 60 × coverage. This is the highest coverage for bovine genome published so far. Tertiary analysis found 6,362,988 SNPs in the bull's genome, 4,045,889 heterozygous and 2,317,099 homozygous variants. Annotation revealed that 4,330,337 of all discovered SNPs were annotated in the dbSNP database (build 137) and therefore 2,032,651 SNPs were novel. Large indel variations accounted for the 245,947,845 bp of the variation in entire genome and their number was 312,879. We also found that small indels (number was 633,310) accounted for the total variation of 2,542,552 nucleotides in the genome. Only 106,768 small indels were listed in the dbSNP. Finally, we identified 2,758 inversions in the genome of the bull covering in total 23,099,054 bp of genome's variation. The largest inversion was 87,440 bp in size. In conclusion, the present study discovered different types of novel variants in bull's genome after high-coverage sequencing. Better knowledge of the functions of these variations is needed.
Measurement and Analysis of Full-Scale Hydraulic Fracture Initiation and Reorientation
NASA Astrophysics Data System (ADS)
Jeffrey, R. G.; Chen, Z. R.; Zhang, X.; Bunger, A. P.; Mills, K. W.
2015-11-01
Hydraulic fracture breakdown and reorientation data collected from two instrumented test borehole sites have been analyzed to assess the effect of the initiation type (axial or transverse) on the treating pressure. Vertical boreholes were drilled and fractures were placed in a conglomerate at depths of 140-180 m in a far-field stress field that favored horizontal fracture growth. Axial initiation resulted in high injection pressure, which was attributed to near-borehole tortuosity generated as the hydraulic fracture reoriented to align with the far-field stresses. Acoustic scanner logging of the boreholes after fracturing demonstrated that, in many cases, axial initiation occurred and when this was the case, treating pressures were high and consistent with near-borehole tortuous fracture paths. A fracture initiation analysis determined that initiation at abrasively cut circumferential slots should occur before axial initiation. Slots were cut to locate the initiation sites and to make transverse fracture initiation more likely. Transverse initiation from the vertical boreholes at pre-cut slots lowered the injection pressures during the fracture treatment by up to 12 MPa for water injected at approximately 500 L per minute.
Full image spectral analysis of elemental emissions from an echelle spectrograph
Spencer, W.A.
2000-01-27
A new algorithm compares the background corrected echelle emission image obtained from reference standards to images of unknowns for quantitative elemental analyses. Wavelength was not used in the calculations but instead pixel position and intensity. The data reduction solution was unique to the particular detector/spectrometer. The approach was found useful for several types of images including ICP, DCP and glow discharge images. The analysis scheme required that the emission pattern of standards and background be held in memory. A dual weighting scheme was used that decreased the importance of pixels in high background areas and enhanced the importance of signals from pixels where the standards had emissions. Threshold values were used to limit the calculations to signals in the linear range of the electronics. Logarithmic weighting, (by taking the square root), was found to work well for weighting pixels from the standards. This assured that minor emissions had some influence on the data fit. In the program the best-fit scalar was determined using simple iterative guess, change and test approaches. The test looked for the minimum least square residual value in the areas of the flagged pixels.
RSAT peak-motifs: motif analysis in full-size ChIP-seq datasets.
Thomas-Chollier, Morgane; Herrmann, Carl; Defrance, Matthieu; Sand, Olivier; Thieffry, Denis; van Helden, Jacques
2012-02-01
ChIP-seq is increasingly used to characterize transcription factor binding and chromatin marks at a genomic scale. Various tools are now available to extract binding motifs from peak data sets. However, most approaches are only available as command-line programs, or via a website but with size restrictions. We present peak-motifs, a computational pipeline that discovers motifs in peak sequences, compares them with databases, exports putative binding sites for visualization in the UCSC genome browser and generates an extensive report suited for both naive and expert users. It relies on time- and memory-efficient algorithms enabling the treatment of several thousand peaks within minutes. Regarding time efficiency, peak-motifs outperforms all comparable tools by several orders of magnitude. We demonstrate its accuracy by analyzing data sets ranging from 4000 to 1,28,000 peaks for 12 embryonic stem cell-specific transcription factors. In all cases, the program finds the expected motifs and returns additional motifs potentially bound by cofactors. We further apply peak-motifs to discover tissue-specific motifs in peak collections for the p300 transcriptional co-activator. To our knowledge, peak-motifs is the only tool that performs a complete motif analysis and offers a user-friendly web interface without any restriction on sequence size or number of peaks.
Full pedigree quantitative trait locus analysis in commercial pigs using variance components.
de Koning, D J; Pong-Wong, R; Varona, L; Evans, G J; Giuffra, E; Sanchez, A; Plastow, G; Noguera, J L; Andersson, L; Haley, C S
2003-09-01
In commercial livestock populations, QTL detection methods often use existing half-sib family structures and ignore additional relationships within and between families. We reanalyzed the data from a large QTL confirmation experiment with 10 pig lines and 10 chromosome regions using identity-by-descent (IBD) scores and variance component analyses. The IBD scores were obtained using a Monte Carlo Markov Chain method, as implemented in the LOKI software, and were used to model a putative QTL in a mixed animal model. The analyses revealed 61 QTL at a nominal 5% level (out of 650 tests). Twenty-seven QTL mapped to areas where QTL have been reported, and eight of these exceeded the threshold to claim confirmed linkage (P < 0.01). Forty-two of the putative QTL were detected previously using half-sib analyses, whereas 46 QTL previously identified by half-sib analyses could not be confirmed using the variance component approach. Some of the differences could be traced back to the underlying assumptions between the two methods. Using a deterministic approach to estimate IBD scores on a subset of the data gave very similar results to LOKI. We have demonstrated the feasibility of applying variance component QTL analysis to a large amount of data, equivalent to a genome scan. In many situations, the deterministic IBD approach offers a fast alternative to LOKI.
Full genome analysis of a novel type II feline coronavirus NTU156.
Lin, Chao-Nan; Chang, Ruey-Yi; Su, Bi-Ling; Chueh, Ling-Ling
2013-04-01
Infections by type II feline coronaviruses (FCoVs) have been shown to be significantly correlated with fatal feline infectious peritonitis (FIP). Despite nearly six decades having passed since its first emergence, different studies have shown that type II FCoV represents only a small portion of the total FCoV seropositivity in cats; hence, there is very limited knowledge of the evolution of type II FCoV. To elucidate the correlation between viral emergence and FIP, a local isolate (NTU156) that was derived from a FIP cat was analyzed along with other worldwide strains. Containing an in-frame deletion of 442 nucleotides in open reading frame 3c, the complete genome size of NTU156 (28,897 nucleotides) appears to be the smallest among the known type II feline coronaviruses. Bootscan analysis revealed that NTU156 evolved from two crossover events between type I FCoV and canine coronavirus, with recombination sites located in the RNA-dependent RNA polymerase and M genes. With an exchange of nearly one-third of the genome with other members of alphacoronaviruses, the new emerging virus could gain new antigenicity, posing a threat to cats that either have been infected with a type I virus before or never have been infected with FCoV.
NASA Astrophysics Data System (ADS)
Liu, Suzhen; Zhang, Yanwei; Zhang, Chuang; Yang, Qingxin
2017-02-01
Lamb waves are widely used in nondestructive testing (NDT) and structural health monitoring (SHM) for its obvious advantages, such as good directionality, longer-range propagation and lower loss etc. However, it is difficult to analysis and to interpret the echo signals because of its multi-modes and dispersion. In this paper, the properties of single-mode Lamb waves which were excited by double EMAT were studied based on the principles of multi-modes and the characteristics of wave structure. Simulation results show that the double transducer excitation structure can stimulate single-mode Lamb waves and eliminate the extra modes, which are produced by modal conversion at ends of the specimen. The single-mode excitation of Lamb waves is beneficial to reduce the difficulty of signal processing and provide reliable information to locate the defect. The researches in this paper can be used as a theoretical basis to design double transducer excitation system.
Zhang, Y. S.; Cai, F.; Xu, W. M.
2011-09-28
The ship motion equation with a cosine wave excitement force describes the slip moments in regular waves. A new kind of wave excitement force model, with the form as sums of cosine functions was proposed to describe ship rolling in irregular waves. Ship rolling time series were obtained by solving the ship motion equation with the fourth-order-Runger-Kutta method. These rolling time series were synthetically analyzed with methods of phase-space track, power spectrum, primary component analysis, and the largest Lyapunove exponent. Simulation results show that ship rolling presents some chaotic characteristic when the wave excitement force was applied by sums of cosine functions. The result well explains the course of ship rolling's chaotic mechanism and is useful for ship hydrodynamic study.
Spiral implants bearing full-arch rehabilitation: analysis of clinical outcome.
Danza, Matteo; Grecchi, Francesco; Zollino, Ilaria; Casadio, Claudia; Carinci, Francesco
2011-08-01
A spiral implant (SPI) is a conical internal helix implant with a variable thread design which confers the characteristic of self drilling, self tapping, and self bone condensing. The effectiveness of this type of implant has been reported in several clinical situations. However, because there are no reports that specifically focus on one of the biggest challenges in oral rehabilitation, that is, full arch rehabilitation, it was decided to perform a retrospective study. The study population was composed of 23 patients (12 women and 11 men, median age 57 years) for evaluation and implant treatment between January 2005 and June 2009. Two-hundred six spiral family implants (SFIs) were inserted with a mean postloading follow-up of 23 months. Several variables were investigated: demographic (age and gender), anatomic (maxilla and mandible, tooth site), implant (type, length, and diameter), surgical (surgeon, postextractive, flapless technique, grafts), and prosthetic (implant/crown ratio, dentition in the antagonist arch, type of loading, and computerized tomography [CT] planning) variables. Implant loss and peri-implant bone resorption were evaluated. Univariate and multivariate tests were performed. Survival and success rates were 97.1% and 82.5%, respectively. Only implant length and implant/crown ratio showed statistical significance in determining a better clinical outcome. In conclusion, SFIs are a reliable tool for the most difficult cases of oral rehabilitation. No differences were detected among implant type. Length and implant/crown ratio can influence the crestal bone resorption with better result for longer fixtures and a higher implant/crown ratio. In addition, banked bone derived from living donors can be used to restore alveolar ridge augmentation without adverse effects. Finally, flapless and CT-planned surgery did not significantly increase the clinical outcome in most complex rehabilitation.
Qin, Shujia; Miao, Lei; Xi, Ning; Wang, Yuechao; Yang, Chunmin
2010-01-01
The surface electrogastrogram (EGG) records the electrical slow wave of the stomach noninvasively, whose frequency is a useful clinical indicator of the state of gastric motility. Estimators based on the periodogram method are widely adopted to obtain this parameter. But they are with a poor frequency domain resolution when the data window is short in time-frequency analysis, and have not taken full advantage of the slow wave model. We present a modified multiple signal classification (MUSIC) method for computing the frequency from surface EGG records, developing it into a real-time time-frequency analysis algorithm. Simulations indicate that the modified MUSIC method has better performance in resolution and precision in the sinusoid-like resultant signal frequency detecting than periodogram. Volunteer data tests show that the modified MUSIC method is stable and efficient for clinical applications, and reduces the danger of pseudo peaks for the diagnosis.
Epidemiology and full genome sequence analysis of H1N1pdm09 from Northeast China.
Li, Xiaoyan; Kong, Mei; Chen, Jinying; Su, Xu; Zou, Ming; Guo, Liru; Li, Lin; Ding, Jianqing
2013-10-01
Pandemic influenza A (H1N1) 2009 virus (H1N1pdm09) was a novel tri-assortment virus that emerged in Mexico and North America in 2009 and caused the first influenza pandemic in the 21st century. This study investigated the prevalence pattern and molecular characteristics of H1N1pdm09 in three continuous years from April 2009 to March 2012 in populations of Tianjin, Northeast China. Totally, 3,068 influenza viruses (25.4 %) were detected from 12,089 respiratory specimens. Among them, 41.4 % (1,269/3,068) were H1N1pdm09 positive. 15.1 % (192/1,269) severe respiratory infection cases were H1N1pdm09 positive. H1N1pdm09 was the predominant prevalence subtype in October 2009-March 2010 (69.1 %, 930/1,346) and October 2010-March 2011 (42.1 %, 220/523). Eight isolated H1N1pdm09 viruses from severe infection/death cases in three different years were selected to sequence the whole genome through splicing the sequences following 46 PCRs. HA sequences of seven H1N1pdm09 isolates from mild infection cases were detected. Phylogenetic analysis showed that HA, NA, M, NP and NS genes of H1N1pdm09 viruses gathered together with swine influenza A (H1N1), whereas PB2 and PA genes originated from avian influenza virus, and PB1 gene originated from human seasonal influenza virus. Identity analysis indicated that all the genes were highly conserved. Compared with vaccine strain A/California/07/2009(H1N1), the maximal mutation gene was HA (0.7-2.6 %), then NA (0.6-1.7 %), last one was M (mutation rate 0-0.6 %). More site substitutions were observed in 2011 isolates than in 2009 and 2010 isolates of HA (p = 0.002), NA (p = 0.003) and PA (p = 0.001) proteins. The amino acid substitution rates were varied among eight gene segments, ranging from 7.39 × 10(-4) for PB2 to 7.40 × 10(-3) for NA. The higher d N / d S rates were observed in HA, PA and NS segments in H1N1pdm09 in Tianjin. Three HA amino acid site substitutions occurred at the HA receptor-binding sites and
Deán, J Luis; Trillo, Cristina; Doval, Angel F; Fernández, José L
2008-09-01
A method based on fitting the theoretical dispersion curves of Lamb waves to experimental data is presented to determine the thickness and two independent elastic constants of aluminum plates a few millimeters thick. The waves are generated by means of the wedge method using a narrowband source, selecting the wedge angle and the acoustic frequency f so that mainly one mode is excited. A self-developed pulsed electronic speckle pattern interferometry system renders a two dimensional map of the out-of-plane acoustic displacement field at the plate surface, which allows an accurate measurement of the acoustic wavelength lambda(1). For any mode, the relation between lambda(1) and f depends on the three unknown parameters, so at least three experimental measurements (lambda(1i),f(i)) with different frequencies and/or different modes are required to calculate them. The suitability of different Lamb modes to determine each parameter when the others are known is studied, as well as the conditions that the experimental set of values must fulfill to calculate all three parameters. Numerous Lamb modes at different frequencies are generated in each plate, and a fitting is made based on the minimization of the error function, resulting in an accuracy better than 1%.
Analysis of non linear partially standing waves from 3D velocity measurements
NASA Astrophysics Data System (ADS)
Drevard, D.; Rey, V.; Svendsen, Ib; Fraunie, P.
2003-04-01
Surface gravity waves in the ocean exhibit an energy spectrum distributed in both frequency and direction of propagation. Wave data collection is of great importance in coastal zones for engineering and scientific studies. In particular, partially standing waves measurements near coastal structures and steep or barred beaches may be a requirement, for instance for morphodynamic studies. The aim of the present study is the analysis of partially standing surface waves icluding non-linear effects. According to 1st order Stokes theory, synchronous measurements of horizontal and vertical velocity components allow calculation of rate of standing waves (Drevard et al, 2003). In the present study, it is demonstrated that for deep water conditions, partially standing 2nd order Stokes waves induced velocity field is still represented by the 1st order solution for the velocity potential contrary to the surface elevation which exhibits harmonic components. For intermediate water depth, harmonic components appear not only in the surface elevation but also in the velocity fields, but their weight remains much smaller, because of the vertical decreasing wave induced motion. For irregular waves, the influence of the spectrum width on the non-linear effects in the analysis is discussed. Keywords: Wave measurements ; reflection ; non-linear effects Acknowledgements: This work was initiated during the stay of Prof. Ib Svendsen, as invited Professor, at LSEET in autumn 2002. This study is carried out in the framework of the Scientific French National Programmes PNEC ART7 and PATOM. Their financial supports are acknowledged References: Drevard, D., Meuret, A., Rey, V. Piazzola, J. And Dolle, A.. (2002). "Partially reflected waves measurements using Acoustic Doppler Velocimeter (ADV)", Submitted to ISOPE 03, Honolulu, Hawaii, May 2003.
NASA Astrophysics Data System (ADS)
Ekström, Göran
2015-04-01
For shallow sources, Love and Rayleigh waves are the largest seismic phases recorded at teleseismic distances. The utility of these waves for earthquake characterization was traditionally limited to magnitude estimation, since geographically variable dispersion makes it difficult to determine useful travel-time information from the waveforms. Path delays due to heterogeneity of several tens of seconds are typical for waves at 50 sec period, and these delays must be accounted for with precision and accuracy in order to extract propagation-phase and source-phase information. Advances in tomographic mapping of global surface-wave phase velocities, and continuous growth and improvements of seismographic networks around the world, now make possible new applications of surface waves for earthquake monitoring and analysis. Through continuous back propagation of the long-period seismic wave field recorded by globally distributed stations, nearly all shallow earthquakes greater than M=5 can be detected and located with a precision of 25 km. Some of the detected events do not appear in standard earthquake catalogs and correspond to non-tectonic earthquakes, including landslides, glacier calving, and volcanic events. With the improved ability to predict complex propagation effects of surface waves across a heterogeneous Earth, moment-tensor and force representations of seismic sources can be routinely determined for all earthquakes greater than M=5 by waveform fitting of surface waves. A current area of progress in the use of surface waves for earthquake studies is the determination of precise relative locations of remote seismicity by systematic cross correlation and analysis of surface waves generated by neighboring sources. Preliminary results indicate that a location precision of 5 km may be achievable in many areas of the world.
Analysis of Rayleigh wave interactions for surface crack characterization
NASA Astrophysics Data System (ADS)
Rosli, M. H.; Fan, Y.; Edwards, R. S.
2012-05-01
Electromagnetic acoustic transducers (EMATs) have been used in pitch-catch mode for a better characterization of surface cracks in metals. The system, which combines the measurement of Rayleigh wave velocity in the in-plane and out-of-plane directions, has been used to understand the interaction of Rayleigh waves with inclined surface cracks. This shows a stronger and more prominent enhancement pattern when compared to the enhancement caused by cracks which are normal to the surface. In addition, measurements in the far-field are combined with the near-field enhancement measurement, with a view to characterize the cracks. An algorithm for characterizing surface cracks is presented. A finite element method model has been computed to simulate the experiment, and the cause of the prominent enhancement in the inclined cracks is explained.
Local stability analysis for a planar shock wave
NASA Technical Reports Server (NTRS)
Salas, M. D.
1984-01-01
A procedure to study the local stability of planar shock waves is presented. The procedure is applied to a Rankine-Hugoniot shock in a divergent/convergent nozzle, to an isentropic shock in a divergent/convergent nozzle, and to Rankine-Hugoniot shocks attached to wedges and cones. It is shown that for each case, the equation governing the shock motion is equivalent to the damped harmonic oscillator equation.
Ocean Surface Wave Optical Roughness - Analysis of Innovative Measurements
2013-09-30
REFERENCES Banner, M . L ., C. J. Zappa, and J. Gemmrich (2013), A note on Phillips’ spectral framework for ocean whitecaps, Journal of Physical...C. J. Zappa, M . L . Banner, and R. P. Morison (2013), Wave breaking in developing and mature seas, Journal of Geophysical Research - Oceans, 118...doi:10.1002/jgrc.20334. Gemmrich, J. R., M . L . Banner, and C. Garrett (2008), Spectrally resolved energy dissipation and momentum flux of breaking
Analysis of Gravity Waves Structures Visible in Noctilucent Cloud Images
2010-01-01
author. Tel.: +1 4357978128. E-mail address: dominiquepautet@gmail.com Keywords: Noctilucent clouds ( NLC ); Mesosphere lower thermosphere (MLT...clouds ( NLC ) are high-altitude bright cloud formations visible under certain conditions from high-latitude places during the summer months. Even if the...visible in the NLC images taken every summer night since 2004 from Stockholm, Sweden (59.4ºN). The parameters of 30 short-period gravity wave events
System analysis for millimeter-wave communication satellites
NASA Technical Reports Server (NTRS)
Holland, L. D.; Hilsen, N. B.; Gallagher, J. J.; Stevens, G.
1980-01-01
Research and development needs for millimeter-wave space communication systems are presented. Assumed propagation fade statistics are investigated along with high data rate diversity link and storage. The development of reliable ferrite switches, and high performance receivers and transmitters is discussed, in addition to improved tolerance of dish and lens fabrication for the antennas. The typical cost for using a simplex voice channel via a high capacity 40/50 GHz satellite is presented.
Analysis of unsteady wave processes in a rotating channel
NASA Technical Reports Server (NTRS)
Larosiliere, Louis M.; Mawid, M.
1993-01-01
The impact of passage rotation on the gas dynamic wave processes is analyzed through a numerical simulation of ideal shock-tube flow in a closed rotating-channel. Initial conditions are prescribed by assuming homentropic solid-body rotation. Relevant parameters of the problem such as wheel Mach number, hub-to-tip radius ratio, length-to-tip radius ratio, diaphragm temperature ratio, and diaphragm pressure ratio are varied. The results suggest possible criteria for assessing the consequences of passage rotation on the wave processes, and they may therefore be applicable to pressure-exchange wave rotors. It is shown that for a fixed geometry and initial conditions, the contact interface acquires a distorted three-dimensional time-dependent orientation at non-zero wheel Mach numbers. At a fixed wheel Mach number, the level of distortion depends primarily on the density ratio across the interface as well as the hub-to-tip radius ratio. Rarefaction fronts, shocks, and contact interfaces are observed to propagate faster with increasing wheel Mach number.
Bispectral Analysis of a Langmuir Wave Packet Associated with a Solar Type III Radio Burst
NASA Astrophysics Data System (ADS)
Golla, T.; MacDowall, R. J.; Bergamo, M.
2012-12-01
We present the observations of an intense localized wave packet, obtained by the STEREO spacecraft in the source region of a solar type III radio burst. The FFT spectrum of this wave packet contains a primary peak at the local electron plasma frequency, fpe (Langmuir waves), and two secondary peaks, one at 2fpe (second harmonic) and a second one at 3fpe (third harmonic). The wavelet based time-frequency spectrogram indicates that these spectral peaks are coincident in time. It is found that the bicoherence spectrum, computed using the wavelet based bispectral analysis technique contains two peaks, one at (fpe, fpe) and a second one at (2fpe, fpe). The high values of the bicoherences of these spectral peaks, which quantify the phase coherences amongst the harmonic components provide unambiguous evidence for the three wave interactions L + L' -> T2f{pe}, and L + T2f{pe} -> T3f{pe} in the waveform data, where L and L' are the oppositely propagating Langmuir waves, and T2f{pe} and T3f{pe} are the second and third harmonic electromagnetic waves, respectively. The peak intensity and short duration of this wave packet, which indicate that it is probably a collapsing soliton formed as a result of oscillating two stream instability (OTSI), strongly suggest that the L and L' probably correspond to the OTSI excited oppositely propagating Langmuir waves.
NASA Astrophysics Data System (ADS)
Yuan, T.; Zhao, Y.; Pautet, P.; Cai, X.; Fish, C. S.; Taylor, M. J.
2012-12-01
Gravity wave forcing (GWF) is induced by the momentum deposition during the wave breaking event. It is believed to be the major dynamic source in the mesosphere and lower thermosphere (MLT) that affects not only the global climatological features but also the mesoscale events in this region. The Utah State University (USU) Na Doppler Temperature/Wind lidar set up zonal co-planner beam in June 2011 to measure the zonal momentum flux through zonal wind variance calculations. Meanwhile, the lidar's multi-day continuous full diurnal cycle observations provide opportunity to investigate the GWF on the tidal wave variability and propagations within the mesopause region. In this paper, we are going to discuss the nocturnal GWF revealed by the lidar momentum flux measurements in one collaborative continuous 5-day campaign with Advance Mesospheric Temperature Mapper (AMTM) at USU and the Meteor Wind Radar at Bear Lake Observatory (BLO) in August 2011. The AMTM also captured one intensive mesospheric "Bore" event during one night with strong GWF, while TIMED/SABER data indicates that the temperature inversion layer (thermal duct region for "Bore" propagation) is well over 1000 km in horizontal scale, extending beyond west coast of North America. The correlation between zonal GWF and tidal wave will be investigated, along with planetary wave behavior through this campaign.
Spectrum analysis of seismic surface waves and its applications in seismic landmine detection.
Alam, Mubashir; McClellan, James H; Scott, Waymond R
2007-03-01
In geophysics, spectrum analysis of surface waves (SASW) refers to a noninvasive method for soil characterization. However, the term spectrum analysis can be used in a wider sense to mean a method for determining and identifying various modes of seismic surface waves and their properties such as velocity, polarization, etc. Surface waves travel along the free boundary of a medium and can be easily detected with a transducer placed on the free surface of the boundary. A new method based on vector processing of space-time data obtained from an array of triaxial sensors is proposed to produce high-resolution, multimodal spectra from surface waves. Then individual modes can be identified in the spectrum and reconstructed in the space-time domain; also, reflected waves can be separated easily from forward waves in the spectrum domain. This new SASW method can be used for detecting and locating landmines by analyzing the reflected waves for resonance. Processing examples are presented for numerically generated data, experimental data collected in a laboratory setting, and field data.
Influence of R wave analysis upon diagnostic accuracy of exercise testing in women.
Ilsley, C; Canepa-Anson, R; Westgate, C; Webb, S; Rickards, A; Poole-Wilson, P
1982-01-01
Exercise electrocardiography in women with chest pain is associated with a high incidence of false positive ST segment depression. The recent observation that changes in R wave amplitude during exercise can also be used diagnostically may improve the value of stress testing in women. The results of 12 lead treadmill exercise and coronary angiography were reviewed in 62 women, mean age 51 years, presenting with "angina" without previous myocardial infarction. These were compared with exercise results in 14 healthy asymptomatic volunteers with a mean age of 26 years. In addition to conventional ST analysis, R wave amplitude changes during exercise, measured in leads II, III, a VF, and V4 to 6, were examined. While the sensitivity and specificity of ST and R wave changes were similar at about 67%, their combined interpretation was helpful. If both ST and R wave criteria were negative the predictive accuracy for normal coronary angiography was 94% (17/18). Alternatively, in tests showing both ST depression and an abnormal R wave response, coronary angiography was always abnormal (13/13). None of the normal volunteers developed ST segment depression and 93% (13/14) had a normal R wave response. If both were positive, however, coronary angiography was always abnormal (13/13). Although stress test interpretation in women is difficult, R wave analysis is a useful adjunct to ST change and can improve the predictive accuracy of the test in a significant number of patients. PMID:7093085
Time-of-arrival analysis applied to ELF/VLF wave generation experiments at HAARP
NASA Astrophysics Data System (ADS)
Moore, R. C.; Fujimaru, S.
2012-12-01
Time-of-arrival (TOA) analysis is applied to observations performed during ELF/VLF wave generation experiments at the High-frequency Active Auroral Research Program (HAARP) HF transmitter in Gakona, Alaska. In 2012, a variety of ELF/VLF wave generation techniques were employed to identify the dominant source altitude for each case. Observations were performed for beat-wave modulation, AM modulation, STF modulation, ICD modulation, and cubic frequency modulation, among others. For each of these cases, we identify the dominant ELF/VLF source altitude and compare the experimental results with theoretical HF heating predictions.
A light-curve distortion-wave analysis of eight RS Canum Venaticorum systems
NASA Astrophysics Data System (ADS)
Caton, D. B.
1986-01-01
A program of differential U,B,V photometry of 14 RS CVn systems carried out at Rosemary Hill Observatory in 1978 - 1981 is described, and an analysis of the light curves for the characteristic distortion wave for eight of the systems is presented. The V light curves of the systems are shown. Significant waves were observed in RS CVn, RZ Eri, and RW UMa. No significant waves were found in UX Com, GK Hya, AR Lac, LX Per, or TY Pyx. Unusual light curve distortions were observed in UX Com and AR Lac.
NASA Astrophysics Data System (ADS)
Ji, Yanju; Huang, Wanyu; Yu, Mingmei; Guan, Shanshan; Wang, Yuan; Zhu, Yu
2017-01-01
This article studies full-waveform associated identification method of airborne time-domain electromagnetic method (ATEM) 3-d anomalies based on multiple linear regression analysis method. By using convolution algorithm, full-waveform theoretical responses are computed to derive sample library including switch-off-time period responses and off-time period responses. Extract full-waveform attributes from theoretical responses to derive linear regression equations which are used to identify the geological parameters. In order to improve the precision ulteriorly, we optimize the identification method by separating the sample library into different groups and identify the parameter respectively. Performance of full-waveform associated identification method with field data of wire-loop test experiments with ATEM system in Daedao of Changchun proves that the full-waveform associated identification method is feasible practically.
Numerical analysis of the wave force acting on a cylinder in regular waves using the MPS method
NASA Astrophysics Data System (ADS)
Song, Xuemin; Shibata, Kazuya; Nihei, Yasunori; Koshizuka, Seiichi
2016-03-01
We simulated the interactions between a second-order Stokes wave and vertical circular cylinder in a three-dimensional numerical wave tank using the moving particle semi-implicit method. The numerical wave tank was modified to generate a series of Stokes waves. Fluid-structure interactions were simulated under the same wave conditions as the model experiments. We compared the hydrodynamic coefficients obtained by the simulations with those of the experiment to validate this method. We also simulated the wave force around a free surface using the developed method in different wave conditions.
Phase velocity spectrum analysis for a time delay comb transducer for guided wave mode excitation
Quarry, M J; Rose, J L
2000-09-26
A theoretical model for the analysis of ultrasonic guided wave mode excitation of a comb transducer with time delay features was developed. Time delay characteristics are included via a Fourier transform into the frequency domain. The phase velocity spectrum can be used to determine the mode excitation on the phase velocity dispersion curves for a given structure. Experimental and theoretical results demonstrate the tuning of guided wave modes using a time delay comb transducer.
Analysis of wave-like oscillations in parameters of sporadic E layer and neutral atmosphere
NASA Astrophysics Data System (ADS)
Mošna, Z.; Koucká Knížová, P.
2012-12-01
The present study mainly concerns the wave-like activity in the ionospheric sporadic E layer (Es) and in the lower lying stratosphere. The proposed analysis involves parameters describing the state of plasma in the sporadic E layer. Critical frequencies foEs and layer heights hEs were measured at the Pruhonice station (50°N, 14.5°E) during summer campaigns 2004, 2006 and 2008. Further, we use neutral atmosphere (temperature data at 10 hPa) data from the same time interval. The analysis concentrates on vertically propagating wave-like structures within distant atmospheric regions. By means of continuous wavelet transform (CWT) we have detected significant wave-like oscillation at periods covering tidal and planetary oscillation domains both in the Es layer parameters (some of them were reported earlier, for instance in works of Abdu et al., 2003; Pancheva and Mitchel, 2004; Pancheva et al., 2003; Šauli and Bourdillon, 2008) and in stratospheric temperature variations. Further analyses using cross wavelet transform (XWT) and wavelet coherence analysis (WTC) show that despite high wave-like activity in a wide period range, there are only limited coherent wave-like bursts present in both spectra. Such common coherent wave bursts occur on periods close to eigen-periods of the terrestrial atmosphere. We suppose that vertical coupling between atmospheric regions realized by vertically propagating planetary waves occurs predominantly on periods close to those of Rossby modes. Analysis of the phase shift between data from distant atmospheric regions reveals high variability and very likely supports the non-linear scenario of the vertical coupling provided by planetary waves.
Rigorous coupled wave analysis of acousto-optics with relativistic considerations.
Xia, Guoqiang; Zheng, Weijian; Lei, Zhenggang; Zhang, Ruolan
2015-09-01
A relativistic analysis of acousto-optics is presented, and a rigorous coupled wave analysis is generalized for the diffraction of the acousto-optical effect. An acoustic wave generates a grating with temporally and spatially modulated permittivity, hindering direct applications of the rigorous coupled wave analysis for the acousto-optical effect. In a reference frame which moves with the acoustic wave, the grating is static, the medium moves, and the coupled wave equations for the static grating may be derived. Floquet's theorem is then applied to cast these equations into an eigenproblem. Using a Lorentz transformation, the electromagnetic fields in the grating region are transformed to the lab frame where the medium is at rest, and relativistic Doppler frequency shifts are introduced into various diffraction orders. In the lab frame, the boundary conditions are considered and the diffraction efficiencies of various orders are determined. This method is rigorous and general, and the plane waves in the resulting expansion satisfy the dispersion relation of the medium and are propagation modes. Properties of various Bragg diffractions are results, rather than preconditions, of this method. Simulations of an acousto-optical tunable filter made by paratellurite, TeO(2), are given as examples.
A comprehensive analysis of ion cyclotron waves in the equatorial magnetosphere of Saturn
NASA Astrophysics Data System (ADS)
Meeks, Zachary; Simon, Sven; Kabanovic, Slawa
2016-09-01
We present a comprehensive analysis of ion cyclotron waves in the equatorial magnetosphere of Saturn, considering all magnetic field data collected during the Cassini era (totaling to over 4 years of data from the equatorial plane). This dataset includes eight targeted flybys of Enceladus, three targeted flybys of Dione, and three targeted flybys of Rhea. Because all remaining orbits of Cassini are high-inclination, our study provides the complete map of ion cyclotron waves in Saturn's equatorial magnetosphere during the Cassini era. We provide catalogs of the radial and longitudinal dependencies of the occurrence rate and amplitude of the ion cyclotron fundamental and first harmonic wave modes. The fundamental wave mode is omnipresent between the orbits of Enceladus and Dione and evenly distributed across all Local Times. The occurrence rate of the fundamental mode displays a Fermi-Dirac-like profile with respect to radial distance from Saturn. Detection of the first harmonic mode is a rare event occurring in only 0.49% of measurements taken and always in conjunction with the fundamental mode. We also search for a dependency of the ion cyclotron wave field on the orbital positions of the icy moons Enceladus, Dione, and Rhea. On magnetospheric length scales, the wave field is independent of the moons' orbital positions. For Enceladus, we analyze wave amplitude profiles of seven close flybys (E9, E12, E13, E14, E17, E18, and E19), which occurred during the studied trajectory segments, to look for any local effects of Enceladan plume variability on the wave field. We find that even in the close vicinity of Enceladus, the wave amplitudes display no discernible dependency on Enceladus' angular distance to its orbital apocenter. Thus, the correlation between plume activity and angular distance to apocenter proposed by Hedman et al. (2013) does not leave a clearly distinguishable imprint in the ion cyclotron wave field.
Surface Acoustic Wave Monitor for Deposition and Analysis of Ultra-Thin Films
NASA Technical Reports Server (NTRS)
Hines, Jacqueline H. (Inventor)
2015-01-01
A surface acoustic wave (SAW) based thin film deposition monitor device and system for monitoring the deposition of ultra-thin films and nanomaterials and the analysis thereof is characterized by acoustic wave device embodiments that include differential delay line device designs, and which can optionally have integral reference devices fabricated on the same substrate as the sensing device, or on a separate device in thermal contact with the film monitoring/analysis device, in order to provide inherently temperature compensated measurements. These deposition monitor and analysis devices can include inherent temperature compensation, higher sensitivity to surface interactions than quartz crystal microbalance (QCM) devices, and the ability to operate at extreme temperatures.
Ocean Surface Wave Optical Roughness - Analysis of Innovative Measurements
2012-09-30
parameterization of air-sea fluxes: Updates and verification for the COARE algorithm, J. Climate, 16, 571-591. Gemmrich, J. R., M . L . Banner, and C...of surface slopes, Annu. Rev. Mar. Sci., 1(doi: 10.1146/annurev.marine.010908.163940), 377–415. Phillips, O. M ., F. L . Posner, and J. P. Hanson...Zappa, C. J., M . L . Banner, H. Schultz, A. Corrada-Emmanuel, L . B. Wolff, and J. Yalcin (2008), Retrieval of short ocean wave slope using polarimetric
Propagation analysis of forward degenerate four-wave mixing
NASA Astrophysics Data System (ADS)
Maruani, A.
1980-05-01
The problem of forward degenerate four-wave mixing in one- and two-photon absorbing media is shown to be analytically solvable for all current experimental conditions. The resonant interaction is studied in detail, and optical Kerr effect, auto and induced two-photon absorption, and nonlinear gain are taken explicitly into account. It is demonstrated how the Kerr effect limits the efficiency of the process. Around a two-photon resonance, the problem of the nearly parallel propagation of two beams undergoing auto and induced two-photon absorption is solved. The solutions are obtained in a form simple enough to allow numerical computations on a programmable calculator.
Analysis on short-range millimetre wave scattering imaging system
NASA Astrophysics Data System (ADS)
Zhu, Li; Li, Xing-Guo; Lou, Guo-Wei; Zhang, Chao
2011-08-01
A system for short-range millimetre wave(MMW) active imaging was developed, including transceiver antenna, scanning system, transceiver front-end, signal processing. A target within a few meters or even a few centimeters can be imaged. The overall structure of the imaging system and imaging method were researched. The short-range scattering imaging formula was derived from the spectral distribution shift view, which can simplify the method. Phase compensation factor was introduced to improve the imaging resolution. The relationship between the sampling frequency and scanning speed was analyzed to optimize the system parameters, which can improve image quality and system efficiency.
Polar Plasma Wave Investigation Data Analysis in the Extended Mission
NASA Technical Reports Server (NTRS)
Gurnett, Donald A.; Hoffman, Robert A. (Technical Monitor)
2002-01-01
This Summary of Research is being submitted to NASA Goddard Space Flight Center in fulfillment of the final reporting requirement under Grant NAG5-7943, which terminated on March 31, 2002. The following contains a summary of the significant accomplishments of the Polar Plasma Wave Investigation (PWI) team during the period of the grant, April 1, 1999 through March 31, 2002, and a listing of all of the publications that resulted from work carried out under the grant. Also included below is a listing of the numerous public outreach activities that took place during the period of the grant in which the Polar mission and Polar PWI science were discussed.
Pseudospectral modeling and dispersion analysis of Rayleigh waves in viscoelastic media
Zhang, K.; Luo, Y.; Xia, J.; Chen, C.
2011-01-01
Multichannel Analysis of Surface Waves (MASW) is one of the most widely used techniques in environmental and engineering geophysics to determine shear-wave velocities and dynamic properties, which is based on the elastic layered system theory. Wave propagation in the Earth, however, has been recognized as viscoelastic and the propagation of Rayleigh waves presents substantial differences in viscoelastic media as compared with elastic media. Therefore, it is necessary to carry out numerical simulation and dispersion analysis of Rayleigh waves in viscoelastic media to better understand Rayleigh-wave behaviors in the real world. We apply a pseudospectral method to the calculation of the spatial derivatives using a Chebyshev difference operator in the vertical direction and a Fourier difference operator in the horizontal direction based on the velocity-stress elastodynamic equations and relations of linear viscoelastic solids. This approach stretches the spatial discrete grid to have a minimum grid size near the free surface so that high accuracy and resolution are achieved at the free surface, which allows an effective incorporation of the free surface boundary conditions since the Chebyshev method is nonperiodic. We first use an elastic homogeneous half-space model to demonstrate the accuracy of the pseudospectral method comparing with the analytical solution, and verify the correctness of the numerical modeling results for a viscoelastic half-space comparing the phase velocities of Rayleigh wave between the theoretical values and the dispersive image generated by high-resolution linear Radon transform. We then simulate three types of two-layer models to analyze dispersive-energy characteristics for near-surface applications. Results demonstrate that the phase velocity of Rayleigh waves in viscoelastic media is relatively higher than in elastic media and the fundamental mode increases by 10-16% when the frequency is above 10. Hz due to the velocity dispersion of P
Microseisms and sea wave height in the Ligurian Sea: a preliminary analysis.
NASA Astrophysics Data System (ADS)
Zunino, A.; Ferretti, G.; Scafidi, D.; Barani, S.; Pasta, M.; Spallarossa, D.
2012-04-01
Analysis of the relationship between microseisms and sea wave heights is a fundamental step for understanding the interaction of sea storms with near coastal environment, as well as to gain insights about the possibility of forecasting sea wave heights from microseism. The possibility to predict sea wave heights in the Ligurian Sea is analyzed in this study using about a month of observations from both seismic recordings from a near-coast station (IMI - Imperia Monte Faudo) and significant sea wave heights measured from a buoy (Côte d'Azur buoy, Météo-France network). We focus on the analysis of the vertical component of microseism, which reveals a strong correlation with measured sea wave heights. Looking at the amplitude spectrogram of the vertical component of microseism, we recognize the effects of several meteo-marine events that can be ascribed to Atlantic barometric pressure lows and a series of sea storms in the Ligurian Sea. Moreover, the distinction between primary and secondary microseism is inferred from the spectrogram, even if, because of the superposition of Atlantic and Ligurian effects, it sometimes results difficult. Analysis of microseism polarization reveals a double origin which determines two prevailing orientations, corresponding to Atlantic and Ligurian meteo-marine phenomena. We feature the spectral properties of microseism making a close correlation among (1) the power spectral density spectrum of microseism, (2) the significant sea wave heights measured from the buoy and (3) sea storms occurred in the period under study, showing that there is a good correlation between spectral energy content of microseism and sea wave height. Finally, in order to set up a predictive law, we solve an inverse problem to find the optimal parameters that allow us to estimate the sea wave height given the vertical component of microseism. Specifically, the application of the definition of significant height wave height for the microseism needs the
Analysis of expressed sequence tags generated from full-length enriched cDNA libraries of melon
2011-01-01
Background Melon (Cucumis melo), an economically important vegetable crop, belongs to the Cucurbitaceae family which includes several other important crops such as watermelon, cucumber, and pumpkin. It has served as a model system for sex determination and vascular biology studies. However, genomic resources currently available for melon are limited. Result We constructed eleven full-length enriched and four standard cDNA libraries from fruits, flowers, leaves, roots, cotyledons, and calluses of four different melon genotypes, and generated 71,577 and 22,179 ESTs from full-length enriched and standard cDNA libraries, respectively. These ESTs, together with ~35,000 ESTs available in public domains, were assembled into 24,444 unigenes, which were extensively annotated by comparing their sequences to different protein and functional domain databases, assigning them Gene Ontology (GO) terms, and mapping them onto metabolic pathways. Comparative analysis of melon unigenes and other plant genomes revealed that 75% to 85% of melon unigenes had homologs in other dicot plants, while approximately 70% had homologs in monocot plants. The analysis also identified 6,972 gene families that were conserved across dicot and monocot plants, and 181, 1,192, and 220 gene families specific to fleshy fruit-bearing plants, the Cucurbitaceae family, and melon, respectively. Digital expression analysis identified a total of 175 tissue-specific genes, which provides a valuable gene sequence resource for future genomics and functional studies. Furthermore, we identified 4,068 simple sequence repeats (SSRs) and 3,073 single nucleotide polymorphisms (SNPs) in the melon EST collection. Finally, we obtained a total of 1,382 melon full-length transcripts through the analysis of full-length enriched cDNA clones that were sequenced from both ends. Analysis of these full-length transcripts indicated that sizes of melon 5' and 3' UTRs were similar to those of tomato, but longer than many other dicot
NASA Technical Reports Server (NTRS)
Melnick, Gary J.
1990-01-01
The Mission Operations and Data Analysis Plan is presented for the Submillimeter Wave Astronomy Satellite (SWAS) Project. It defines organizational responsibilities, discusses target selection and navigation, specifies instrument command and data requirements, defines data reduction and analysis hardware and software requirements, and discusses mission operations center staffing requirements.
Numerical analysis of internal waves in stratified wake flows
NASA Astrophysics Data System (ADS)
Fraunie, Philppe
2014-05-01
In laboratory investigations, increased attention has been given to internal waves generated by stationary placed oscillating sources and moving bodies in stratified fluids [1]. The main attention was paid to study flows past bodies of perfect shapes like sphere [2], cylinder [3] of thin strip [3] which are the best theoretical (analytical or numerical) studies. Due to simplicity of geometry, flow around a strip has a potential to investigate separately effects of a drag and lift forces on the body by changing the slope of the horizontally moving strip which can be placed vertically [1], horizontally [2], or be tilted under some angle to the direction of towing velocity [5]. Numeric modeling of a flow past vertical strip uniformly towing with permanent velocity in horizontal direction in a linearly stratified talk which was based on a finite differences solver adapted to the low Reynolds Navier-Stokes equation with transport equation for salinity (LES simulation [6] and RANS [7]) has demonstrated reasonable agreement with data of Schlieren visualization, density marker and probe measurements of internal wave fields. The chosen test cases allowed demonstrating the ability of selected numerical methods to represent stably stratified flows over horizontal strip [4] and hill type 2D obstacles [1, 3] with generation of internal waves. ACKNOWLEDGMENTS This research work was supported by the Region Provence Alpes Côte d'Azur - Modtercom project. The work was also supported by the Russian Foundation for Basic Research (grant 12-01-00128). REFERENCES [1] Chashechkin Yu.D., Mitkin V.V. Experimental study of a fine structure of 2D wakes and mixing past an obstacle in a continuously stratified fluid // Dynamics of Atmosphere and Oceans. 2001. V. 34. P. 165-187. [2] Chashechkin, Yu. D. Hydrodynamics of a sphere in a stratified fluid // Fluid Dyn. 1989. V.24(1) P. 1-7. [3] Mitkin V. V., Chashechkin Yu. D. Transformation of hanging discontinuities into vortex systems in a
NASA Astrophysics Data System (ADS)
Zegrodnik, Michał; Spałek, Józef
2017-01-01
The Gutzwiller wave-function solution of the t -J -U model is considered for the bilayer high-TC superconductor by using the so-called diagrammatic expansion method. The focus is on the influence of the interlayer effects on the superconducting state. The chosen pairing symmetry is a mixture of dx2-y2 symmetry within the layers and the so-called s± symmetry for the interlayer contribution. The analyzed interlayer terms reflect the interlayer electron hopping, the interlayer exchange coupling, and the interlayer pair hopping. The obtained results are compared with selected experimental data corresponding to the copper-based compound Bi-2212 with two Cu-O planes in the unit cell. For the sake of comparison, selected results for the case of the bilayer Hubbard model are also provided. This paper complements our recent results obtained for the single-plane high temperature cuprates [cf. J. Spałek, M. Zegrodnik, and J. Kaczmarczyk, Phys. Rev. B 95, 024506 (2017), 10.1103/PhysRevB.95.024506].
[Velocity estimation of aortic propagation based on radial pulse wave analysis].
Clara, Fernando; Blanco, Gustavo; Casarini, Alfredo; Corral, Pablo; Meschino, Gustavo; Scandurra, Adriana
2011-01-01
We analyzed the possibility of using the radial pulse wave morphology, obtained by a movement transducer, to evaluate the aortic pulse wave velocity. The radial pulse wave signals were obtained by using a transducer, located on the pulse palpation area, in 167 healthy normotensive male volunteers, ages 20 to 70. The reflected wave was identified in every case. Also, a speed coefficient was defined as the ratio between the individual's height and the time between the maximum systolic wave and the arrival time of the reflected wave. We found that the specified coefficient in normotensive individuals increased linearly with age, in a similar way to the increase in aortic propagation velocity measured by other methods. The procedure was repeated on another set of 125 individuals with hypertension, without other risk factors, aged between the 3rd and 7th decade. This time we found similar values to normotensive individuals only on the 3th decade, and a pronounced increase on the velocity coefficient at advanced ages was observed. These findings support the feasibility of using this type of signals to indirectly evaluate the propagation velocity together with the increase index, a parameter commonly used in pulse wave analysis.
Multi-method observation and analysis of an impulse wave and tsunami caused by glacier calving
NASA Astrophysics Data System (ADS)
Lüthi, M. P.; Vieli, A.
2015-11-01
Glacier calving can cause violent impulse waves which, upon landfall, can lead to destructive tsunami-like waves. Here we present data acquired during a calving event from Eqip Sermia, an ocean-terminating glacier in West Greenland. During an exceptionally well documented event, the collapse of 9 × 105 m3 ice from a 200 m high ice cliff caused an impulse wave of 50 m height, traveling at a speed of 25-30 m s-1. This wave was filmed from a tour boat in 800 m distance from the calving face, and simultaneously measured with a terrestrial radar interferometer and a tide gauge. Tsunami wave run-up height on the steep opposite shore in 4 km distance was 10-15 m, destroying infrastructure and eroding old vegetation. These observations indicate that such high tsunami waves are a recent phenomenon in the history of this glacier. Analysis of the data shows that only moderately bigger tsunami waves are to be expected in the future, even under rather extreme scenarios.
An analysis of beam parameters on proton-acoustic waves through an analytic approach.
Aytac Kipergil, Esra; Erkol, Hakan; Kaya, Serhat; Gulsen, Gultekin; Unlu, Mehmet
2017-03-02
It has been reported that acoustic waves are generated when a high energy pulsed proton beam is deposited in a small volume within tissue. One possible application of the proton induced acoustics is to get a real-time feedback for intratreatment adjustments by monitoring such acoustic waves. High spatial resolution in ultrasound imaging may reduce proton range uncertainty. Thus, it is crucial to understand the dependence of the acoustic waves on the proton beam characteristics. In this manuscript, firstly, an analytic solution to the proton induced acoustic wave is presented to reveal the dependence of signal on beam parameters, and then combined with an analytic approximation of the Bragg curve. The influence of the beam energy, pulse duration, and beam diameter variation on the acoustic waveform are investigated. Further analysis is performed regarding the Fourier decomposition of proton-acoustic signals. Our results show that smaller spill time of proton beam upsurges the amplitude of acoustic wave for constant number of protons, and hence beneficial for dose monitoring. The increase in the energy of each individual proton in the beam leads to spatial broadening of the Bragg curve, which also yields acoustic waves of greater amplitude. The pulse duration and the beam width of the proton beam do not affect the central frequency of the acoustic wave, but they change the amplitude of the spectral components.
A Stability Analysis for a Hydrodynamic Three-Wave Journal Bearing
NASA Technical Reports Server (NTRS)
Ene, Nicoleta M.; Dimofte, Florin; Keith, Theo G., Jr.
2007-01-01
The influence of the wave amplitude and oil supply pressure on the dynamic behavior of a hydrodynamic three-wave journal bearing is presented. Both, a transient and a small perturbation technique, were used to predict the threshold to fractional frequency whirl (FFW). In addition, the behavior of the rotor after FFW appeared was determined from the transient analysis. The turbulent effects were also included in the computations. Bearings having a diameter of 30 mm, a length of 27.5 mm, and a clearance of 35 microns were analyzed. Numerical results were compared to experimental results obtained at the NASA GRC. Numerical and experimental results showed that the above-mentioned wave bearing with a wave amplitude ratio of 0.305 operates stably at rotational speeds up to 60,000 rpm, regardless of the oil supply pressure. For smaller wave amplitude ratios, a threshold of stability was found. It was observed that the threshold of stability for lower wave amplitude strongly depends on the oil supply pressure and on the wave amplitude. When the FFW occurs, the journal center maintains its trajectory inside the bearing clearance and therefore the rotor can be run safely without damaging the bearing surfaces.
Viscosity measurement based on shear-wave laser speckle contrast analysis
NASA Astrophysics Data System (ADS)
Cheng, Yi; Li, Sinan; Eckersley, Robert J.; Elson, Daniel S.; Tang, Meng-Xing
2013-12-01
Tissue viscosity is correlated with tissue pathological changes and provides information for tissue characterization. In this study, we report an optical method to track continuous shear-wave propagation at centimeter depths in an optically turbid medium. Shear-wave attenuation coefficients were measured at multiple frequencies using shear-wave laser speckle contrast analysis (SW-LASCA) to quantitatively estimate tissue viscosity using the Voigt model. Shear waves were generated within tissue-mimicking phantoms by an amplitude-modulated ultrasound (modulation frequency: 100 to 600 Hz) and tracked by time-resolved laser speckle contrast difference received on a charged-coupled device camera. Averaged contrast difference over a selected time window was related to shear-wave amplitude and used to calculate the shear-wave attenuation coefficient. Phantoms of varying viscosities (0.1 and 0.3 Pa s) were studied. Attenuation coefficients for different shear-wave frequencies (100 to 600 Hz) were calculated. Derived viscosity values had a maximum standard deviation of 9%, and these values were consistent with the independent measurements reported in a previous study using nonoptical methods.
NASA Astrophysics Data System (ADS)
Matsuda, Takashi S.; Nakamura, Takuji; Murphy, Damian; Tsutsumi, Masaki; Moffat-Griffin, Tracy; Zhao, Yucheng; Pautet, Pierre-Dominique; Ejiri, Mitsumu K.; Taylor, Michael
2016-07-01
ANGWIN (Antarctic Gravity Wave Imaging/Instrument Network) is an international airglow imager/instrument network in the Antarctic, which commenced observations in 2011. It seeks to reveal characteristics of mesospheric gravity waves, and to study sources, propagation, breaking of the gravity waves over the Antarctic and the effects on general circulation and upper atmosphere. In this study, we compared distributions of horizontal phase velocity of the gravity waves at around 90 km altitude observed in the mesospheric airglow imaging over different locations using our new statistical analysis method of 3-D Fourier transform, developed by Matsuda et al. (2014). Results from the airglow imagers at four stations at Syowa (69S, 40E), Halley (76S, 27W), Davis (69S, 78E) and McMurdo (78S, 156E) out of the ANGWIN imagers have been compared, for the observation period between April 6 and May 21 in 2013. In addition to the horizontal distribution of propagation and phase speed, gravity wave energies have been quantitatively compared, indicating a smaller GW activity in higher latitude stations. We further investigated frequency dependence of gravity wave propagation direction, as well as nightly variation of the gravity wave direction and correlation with the background wind variations. We found that variation of propagation direction is partly due to the effect of background wind in the middle atmosphere, but variation of wave sources could play important role as well. Secondary wave generation is also needed to explain the observed results.
NASA Astrophysics Data System (ADS)
Ashton, Andrew D.; Murray, A. Brad
2006-12-01
Recent research has revealed that the plan view evolution of a coast due to gradients in alongshore sediment transport is highly dependant upon the angles at which waves approach the shore, giving rise to an instability in shoreline shape that can generate different types of naturally occurring coastal landforms, including capes, flying spits, and alongshore sand waves. This instability merely requires that alongshore sediment flux is maximized for a given deepwater wave angle, a maximum that occurs between 35° and 50° for several common alongshore sediment transport formulae. Here we introduce metrics that sum over records of wave data to quantify the long-term stability of wave climates and to investigate how wave climates change along a coast. For Long Point, a flying spit on the north shore of Lake Erie, Canada, wave climate metrics suggest that unstable waves have shaped the spit and, furthermore, that smaller-scale alongshore sand waves occur along the spit at the same locations where the wave climate becomes unstable. A shoreline aligned along the trend of the Carolina Capes, United States, would be dominated by high-angle waves; numerical simulations driven by a comparable wave climate develop a similarly shaped cuspate coast. Local wave climates along these simulated capes and the Carolina Capes show similar trends: Shoreline reorientation and shadowing from neighboring capes causes most of the coast to experience locally stable wave climates despite regional instability.
An analysis of interfacial waves and air ingestion mechanisms
NASA Astrophysics Data System (ADS)
Galimov, Azat
This research was focused on developing analytical methods with which to derive the functional forms of the various interfacial forces in two-fluid models [Galimov et al., 2004], and on the Direct Numerical Simulations (DNS) of traveling breaking waves and plunging liquid jets. Analytical results are presented for a stable stratified wavy two-phase flow and the associated interfacial force densities of a two-fluid model. In particular, the non-drag interfacial force density [Drew & Passman, 1998], the Reynolds stress tensor, and the term ( p˜cli -pcl)∇alphacl, which drives surface waves, were derived, where p˜cli is interfacial average pressure, pcl is the average pressure, and alphacl is the volume fraction of the continuous liquid phase. These functional forms are potentially useful for developing two-fluid model closure relations for computational multiphase fluid dynamics (CMFD) numerical solvers. Moreover, it appears that this approach can be generalized to other flow regimes (e.g., annular flows). A comparison of the analytical and ensemble-averaged DNS results show good agreement, and it appears that this approach can be used to develop phenomenological flow-regime-specific closure laws for two-fluid models [Lahey & Drew, 2004], [Lahey, 2005]. A successful 2-D DNS of breaking traveling waves was performed. These calculations had periodic boundary conditions and the physical parameters for air/water flow at atmospheric pressure, including a liquid/gas density ratio of 1,000 and representative surface tension and viscosities. Detailed 3-D DNS was also made for a plunging liquid jet. The processes of forming the liquid jet, the associated air cavity, capturing an initial large donut-shaped air bubble, and developing and breaking-up this bubble into smaller bubbles due to liquid shear, were shown. These simulations showed that the inertia of the liquid jet initially depressed the pool's surface and the toroidal liquid eddy formed subsequently resulted in air
WaveNet: A Web-Based Metocean Data Access, Processing and Analysis Tool; Part 5 - WW3 Database
2015-02-01
ERDC/CHL CHETN-IV-103 February 2015 Approved for public release; distribution is unlimited. WaveNet: A Web -Based Metocean Data Access, Processing...modeling and planning missions require metocean data (e.g., winds, waves, tides, water levels). WaveNet is a web -based graphical-user-interface (GUI...AND SUBTITLE WaveNet: A Web -Based Metocean Data Access, Processing and Analysis Tool; Part 5 - WW3 Database 5a. CONTRACT NUMBER 5b. GRANT NUMBER
Anisotropic P-wave velocity analysis and seismic imaging in onshore Kutch sedimentary basin of India
NASA Astrophysics Data System (ADS)
Behera, Laxmidhar; Khare, Prakash; Sarkar, Dipankar
2011-08-01
The long-offset P-