Cassam-Chenaï, P; Rousseau, G; Ilmane, A; Bouret, Y; Rey, M
2015-07-21
In previous works, we have introduced an alternative perturbation scheme to find approximate solutions of the spectral problem for the rotation-vibration molecular Hamiltonian. An important feature of our approach is that the zero order Hamiltonian is the direct product of a purely vibrational Hamiltonian with the identity on the rotational degrees of freedom. The convergence of our method for the methane vibrational ground state was very satisfactory and our predictions were quantitative. In the present article, we provide further details on the implementation of the method in the degenerate and quasi-degenerate cases. The quasi-degenerate version of the method is tested on excited polyads of methane, and the results are assessed with respect to a variational treatment. The optimal choice of the size of quasi-degenerate spaces is determined by a trade-off between speed of convergence of the perturbation series and the computational effort to obtain the effective super-Hamiltonian. PMID:26203014
NASA Astrophysics Data System (ADS)
Cassam-Chenaï, P.; Rousseau, G.; Ilmane, A.; Bouret, Y.; Rey, M.
2015-07-01
In previous works, we have introduced an alternative perturbation scheme to find approximate solutions of the spectral problem for the rotation-vibration molecular Hamiltonian. An important feature of our approach is that the zero order Hamiltonian is the direct product of a purely vibrational Hamiltonian with the identity on the rotational degrees of freedom. The convergence of our method for the methane vibrational ground state was very satisfactory and our predictions were quantitative. In the present article, we provide further details on the implementation of the method in the degenerate and quasi-degenerate cases. The quasi-degenerate version of the method is tested on excited polyads of methane, and the results are assessed with respect to a variational treatment. The optimal choice of the size of quasi-degenerate spaces is determined by a trade-off between speed of convergence of the perturbation series and the computational effort to obtain the effective super-Hamiltonian.
Cassam-Chenaï, P. Rousseau, G.; Ilmane, A.; Bouret, Y.; Rey, M.
2015-07-21
In previous works, we have introduced an alternative perturbation scheme to find approximate solutions of the spectral problem for the rotation-vibration molecular Hamiltonian. An important feature of our approach is that the zero order Hamiltonian is the direct product of a purely vibrational Hamiltonian with the identity on the rotational degrees of freedom. The convergence of our method for the methane vibrational ground state was very satisfactory and our predictions were quantitative. In the present article, we provide further details on the implementation of the method in the degenerate and quasi-degenerate cases. The quasi-degenerate version of the method is tested on excited polyads of methane, and the results are assessed with respect to a variational treatment. The optimal choice of the size of quasi-degenerate spaces is determined by a trade-off between speed of convergence of the perturbation series and the computational effort to obtain the effective super-Hamiltonian.
The Ten-Rotation Quasi-periodicity in Sunspot Areas
NASA Astrophysics Data System (ADS)
Getko, R.
2014-06-01
Sunspot-area fluctuations over an epoch of 12 solar cycles (12 - 23) are investigated in detail using wavelets. Getko ( Universal Heliophysical Processes, IAU Symp. 257, 169, 2009) found three significant quasi-periodicities at 10, 17, and 23 solar rotations, but two longer periods could be treated as subharmonics of the ten-rotation quasi-periodicity. Therefore we focused the analysis on the occurrence of this quasi-periodicity during the low- and high-activity periods of each solar cycle. Because of the N - S asymmetry, each solar hemisphere was considered separately. The skewness of each fluctuation-probability distribution suggests that the positive and negative fluctuations could be examined separately. To avoid the problem that occurs when a few strong fluctuations create a wavelet peak, we applied fluctuation transformations for which the amplitudes at the high- and the low-activity periods are almost the same. The wavelet analyses show that the ten-rotation quasi-periodicity is mainly detected during the high-activity periods, but it also exists during a few low-activity periods. The division of each solar hemisphere into 30∘-wide longitude bins and the wavelet calculations for the areas of sunspot clusters belonging to these 30∘ bins enable one to detect longitude zones in which the ten-rotation quasi-periodicity exists. These zones are present during the whole high-activity periods and dominate the integrated spectra.
Hougen, J.T.
1993-12-31
Spectroscopy was used to study the vibrational quasi-continuum arising from internal rotation of the methyl group in acetaldehyde. We now understand the torsion-rotation levels from all 3 torsional states below the top of the torsional barrier. Investigations of four ordinary vibrational states in acetaldehyde are in progress.
KIC 10526294: a slowly rotating B star with rotationally split, quasi-equally spaced gravity modes
NASA Astrophysics Data System (ADS)
Pápics, P. I.; Moravveji, E.; Aerts, C.; Tkachenko, A.; Triana, S. A.; Bloemen, S.; Southworth, J.
2014-10-01
Context. Massive stars are important for the chemical enrichment of the universe. Since internal mixing processes influence their lives, it is very important to place constraints on the corresponding physical parameters, such as core overshooting and the internal rotation profile, so as to calibrate their stellar structure and evolution models. Although asteroseismology has been shown to be able to deliver the most precise constraints so far, the number of detailed seismic studies delivering quantitative results is limited. Aims: Our goal is to extend this limited sample with an in-depth case study and provide a well-constrained set of asteroseismic parameters, contributing to the ongoing mapping efforts of the instability strips of the β Cep and slowly pulsating B (SPB) stars. Methods: We derived fundamental parameters from high-resolution spectra using spectral synthesis techniques. We used custom masks to obtain optimal light curves from the original pixel level data from the Kepler satellite. We used standard time-series analysis tools to construct a set of significant pulsation modes that provide the basis for the seismic analysis carried out afterwards. Results: We find that KIC 10526294 is a cool SPB star, one of the slowest rotators ever found. Despite this, the length of Kepler observations is sufficient to resolve narrow rotationally split multiplets for each of its nineteen quasi-equally spaced dipole modes. The number of detected consecutive (in radial order) dipole modes in this series is higher than ever before. The observed amount of splitting shows an increasing trend towards longer periods, which - largely independent of the seismically calibrated stellar models - points towards a non-rigid internal rotation profile. From the average splitting we deduce a rotation period of ~188 days. From seismic modelling, we find that the star is young with a central hydrogen mass fraction Xc> 0.64; it has a core overshooting αov ≤ 0.15. Based on
NASA Astrophysics Data System (ADS)
Sowmiya, C.; Kothawala, Ali Arshad; Thittai, Arun K.
2016-04-01
During manual palpation of breast masses, the perception of its stiffness and slipperiness are the two commonly used information by the physician. In order to reliably and quantitatively obtain this information several non-invasive elastography techniques have been developed that seek to provide an image of the underlying mechanical properties, mostly stiffness-related. Very few approaches have visualized the "slip" at the lesion-background boundary that only occurs for a loosely-bonded benign lesion. It has been shown that axial-shear strain distribution provides information about underlying slip. One such feature, referred to as "fill-in" was interpreted as a surrogate of the rotation undergone by an asymmetrically-oriented-loosely bonded-benign-lesion under quasi-static compression. However, imaging and direct visualization of the rotation itself has not been addressed yet. In order to accomplish this, the quality of lateral displacement estimation needs to be improved. In this simulation study, we utilize spatial compounding approach and assess the feasibility to obtain good quality rotation elastogram. The angular axial and lateral displacement estimates were obtained at different insonification angles from a phantom containing an elliptical inclusion oriented at 45°, subjected to 1% compression from the top. A multilevel 2D-block matching algorithm was used for displacement tracking and 2D-least square compounding of angular axial and lateral displacement estimates was employed. By varying the maximum steering angle and incremental angle, the improvement in the lateral motion tracking accuracy and its effects on the quality of rotational elastogram were evaluated. Results demonstrate significantly-improved rotation elastogram using this technique.
Hougen, J.T.
1993-12-01
The goal of this project is to use spectroscopic techniques to investigate in detail phenomena involving the vibrational quasi-continuum in a simple physical system. Acetaldehyde was chosen for the study because: (i) methyl groups have been suggested to be important promotors of intramolecular vibrational relaxation, (ii) the internal rotation of a methyl group is an easily describle large-amplitude motion, which should retain its simple character even at high levels of excitation, and (iii) the aldehyde carbonyl group offers the possibility of both vibrational and electronic probing. The present investigation of the ground electronic state has three parts: (1) understanding the {open_quotes}isolated{close_quotes} internal-rotation motion below, at, and above the top of the torsional barrier, (2) understanding in detail traditional (bond stretching and bending) vibrational fundamental and overtone states, and (3) understanding interactions involving states with multiquantum excitations of at least one of these two kinds of motion.
Hydrodynamic turbulence in quasi-Keplerian rotating flows?
NASA Astrophysics Data System (ADS)
Shi, Liang; Avila, Marc; Hof, Bjoern; Liang Shi Team; Marc Avila Team; Bjoern Hof Team
2013-11-01
The origin of turbulence in astrophysical accretion discs has been under scrutiny for decades and remains still unclear. The velocity profiles of discs (Keplerien profiles) are centrifugally stable and therefore a different instability mechanism is required for turbulence to arise. While in hot discs turbulence can be triggered through magnetorotational instability, cooler discs lack sufficient ionization and it is unclear how turbulence sets in. In analogy to other linearly stable flows like pipe and Couette flow, subcritical transition to turbulence may be the mechanism. Recently, experimental studies of Taylor-Couette flow in quasi-Keplerian regime have given conflicting results and numerical simulations of above experimental flows showed that the top and bottom end-wall leads to strong deviations from the Keplerian velocity profile and drives turbulence. In order to clarify this, we perform direct numerical simulations of incompressible Taylor-Couette flow without end walls in the quasi Keplerian regime for Re up to 200000. Strong transient growth is observed and gives rise to strongly disorted motion, suggesting that for large enough Re this mechanism may lead to turbulence even for Keplerian flows. This work is supported by Deutsche Forschungsgemeinschaft (DFG) under project SFB 963 and Max Planck Society.
Spin-orbit coupling and chaotic rotation for coorbital bodies in quasi-circular orbits
Correia, Alexandre C. M.; Robutel, Philippe
2013-12-10
Coorbital bodies are observed around the Sun sharing their orbits with the planets, but also in some pairs of satellites around Saturn. The existence of coorbital planets around other stars has also been proposed. For close-in planets and satellites, the rotation slowly evolves due to dissipative tidal effects until some kind of equilibrium is reached. When the orbits are nearly circular, the rotation period is believed to always end synchronous with the orbital period. Here we demonstrate that for coorbital bodies in quasi-circular orbits, stable non-synchronous rotation is possible for a wide range of mass ratios and body shapes. We show the existence of an entirely new family of spin-orbit resonances at the frequencies n ± kν/2, where n is the orbital mean motion, ν the orbital libration frequency, and k an integer. In addition, when the natural rotational libration frequency due to the axial asymmetry, σ, has the same magnitude as ν, the rotation becomes chaotic. Saturn coorbital satellites are synchronous since ν << σ, but coorbital exoplanets may present non-synchronous or chaotic rotation. Our results prove that the spin dynamics of a body cannot be dissociated from its orbital environment. We further anticipate that a similar mechanism may affect the rotation of bodies in any mean-motion resonance.
Quasi-3D Navier-Stokes model for a rotating airfoil
Shen, W.Z.; Soerensen, J.N.
1999-04-10
The design of blade shapes for wind turbines is typically based on employing the blade-element momentum-theory (BEM) with lift and drag forces determined from 2D measurements. The results obtained are reasonable in the vicinity of the design point, but in stalled conditions the BEM is known to underpredict the forces acting on the blades. Here, a quasi-3D model of the unsteady Navier-Stokes equations in a rotating frame of reference has been developed. The equations governing the flow past a rotating blade are approximated using an order of magnitude analysis on the spanwise derivatives. The model takes into account rotational effects and spanwise outflow at computing expenses in the order of what is typical for similar 2D calculations. Results are presented for both laminar and turbulent flows past blades in pure rotation. In the turbulent case the influence of small-scale turbulence is modelled by the one-equation Baldwin-Barth turbulence model. The computations demonstrate that the main influence of rotation is to increase the maximum lift.
Quasi four-level Tm:LuAG laser
NASA Technical Reports Server (NTRS)
Jani, Mahendra G. (Inventor); Barnes, Norman P. (Inventor); Hutcheson, Ralph L. (Inventor); Rodriguez, Waldo J. (Inventor)
1997-01-01
A quasi four-level solid-state laser is provided. A laser crystal is disposed in a laser cavity. The laser crystal has a LuAG-based host material doped to a final concentration between about 2% and about 7% thulium (Tm) ions. For the more heavily doped final concentrations, the LuAG-based host material is a LuAG seed crystal doped with a small concentration of Tm ions. Laser diode arrays are disposed transversely to the laser crystal for energizing the Tm ions.
NASA Astrophysics Data System (ADS)
Chkhetiani, Otto; Gledzer, Alexey; Gledzer, Evgeny; Kalashnik, Maxim; Khapaev, Alexey; Chernous'ko, Yurii
2015-04-01
Experiments on the excitation of zonal flows in a barotropic rotating annulus with conical bottom have been performed [1,2]. The flow was produced by two methods: mechanical pumping and suction - sourse-sink method [1] and MHD method [2]. The velocity fields have been reconstructed by the particle image velocimetry (PIV) method. Diagrams of regimes are presented in parameters of the dimensionless angular velocity of the zonal flow averaged over the channel width and the dimensionless angular velocity of transport of vortex perturbations of cyclonic and anticyclonic types. Attention is focused on the results for the regions of the diagram with slow motion of vortices with respect to the rotating coordinate system near the parameters for stationary Rossby waves (blocking of circulation). For some parameters of the flow the system with almost immobile blocked anticyclones in the outer part of the flow and rapidly moving cyclones in the main stream appears. We consider some simple linear estimation of blocking conditions [1,2]. It is obatined the solution of Obukhov-Charney equation admitting a long quasi-stationary stage of evolution in which the meridional wave number and value of the total wave energy (close to the maximum value) remained virtually unchanged over long time [3]. This effect is realized in a dominant contribution of the free surface deformation in the potential vorticity. It was shown that this effect can lead to new scenarios phase and amplitude Rossby wave blocking. This work was supported by the Russian Sciense Foundation (Project No 14-05-00847) References [1] Gledzer, A. E., Gledzer, E. B., Khapaev, A. A., & Chernous'ko, Y. L. (2014). Zonal flows, Rossby waves, and vortex transport in laboratory experiments with rotating annular channel. Izvestiya, Atmospheric and Oceanic Physics, 50(2), 122-133. [2] Gledzer, A. E. E., Gledzer, E. B., Khapaev, A. A., & Chkhetiani, O. G. (2013). Experimental manifestation of vortices and Rossby wave blocking at
Kim, S G; Kim, D S; Choe, M S; Lee, W; So, J; Choi, E M
2014-10-01
In this paper, we test the performance of a quasi-optical, internal-gyrotron mode converter. When cold testing mode converters, a rotating higher-order mode is commonly used. However, this requires a nontrivial design and precise alignment. We thus propose a new technique for testing gyrotron mode converters by using a simple, non-rotating, higher-order mode generator. We demonstrate the feasibility of this technique for a W-band gyrotron quasi-optical mode converter by examining the excitation of a TE6,2 mode from a non-rotating mode generator. Our results demonstrate that this new cold-test scheme is an easy and efficient method for verifying the performance of quasi-optical mode converters. PMID:25362436
Differential rotation in a solar-driven quasi-axisymmetric circulation. [of planetary atmospheres
NASA Technical Reports Server (NTRS)
Mayr, H. G.; Harris, I.; Chan, K. L.
1984-01-01
The concept of a quasi-axisymmetric circulation is used to explore the global scale dynamics of planetary atmospheres. A numerical circulation model applicable to Jupiter is presented, and an analytical study is performed elucidating the conditions leading to differential rotation in an atmosphere which is convectively unstable. A linear system forced by solar differential heating is considered, with nonlinear effects arising from advection being represented in the form of eddy diffusion. An empirical, latitudinal spectrum of the observed zonal wind field on Jupiter is discussed. Numerical solutions are presented which reveal banded wind fields with alternating and equatorial zonal jets and a multicellular Ferrel-Thomson meridional circulation consistent with the observed cloud striations on Jupiter. The vertical derivatives are parameterized to construct a simplified one-layer model.
Cremaschini, Claudio; Stuchlík, Zdeněk; Tessarotto, Massimo
2013-05-15
The problem of formulating a kinetic treatment for quasi-stationary collisionless plasmas in axisymmetric systems subject to the possibly independent presence of local strong velocity-shear and supersonic rotation velocities is posed. The theory is developed in the framework of the Vlasov-Maxwell description for multi-species non-relativistic plasmas. Applications to astrophysical accretion discs arising around compact objects and to plasmas in laboratory devices are considered. Explicit solutions for the equilibrium kinetic distribution function (KDF) are constructed based on the identification of the relevant particle adiabatic invariants. These are shown to be expressed in terms of generalized non-isotropic Gaussian distributions. A suitable perturbative theory is then developed which allows for the treatment of non-uniform strong velocity-shear/supersonic plasmas. This yields a series representation for the equilibrium KDF in which the leading-order term depends on both a finite set of fluid fields as well as on the gradients of an appropriate rotational frequency. Constitutive equations for the fluid number density, flow velocity, and pressure tensor are explicitly calculated. As a notable outcome, the discovery of a new mechanism for generating temperature and pressure anisotropies is pointed out, which represents a characteristic feature of plasmas considered here. This is shown to arise as a consequence of the canonical momentum conservation and to contribute to the occurrence of temperature anisotropy in combination with the adiabatic conservation of the particle magnetic moment. The physical relevance of the result and the implications of the kinetic solution for the self-generation of quasi-stationary electrostatic and magnetic fields through a kinetic dynamo are discussed.
QUAGMIRE v1.3: a quasi-geostrophic model for investigating rotating fluids experiments
NASA Astrophysics Data System (ADS)
Williams, P. D.; Haine, T. W. N.; Read, P. L.; Lewis, S. R.; Yamazaki, Y. H.
2008-09-01
QUAGMIRE is a quasi-geostrophic numerical model for performing fast, high-resolution simulations of multi-layer rotating annulus laboratory experiments on a desktop personal computer. The model uses a hybrid finite-difference/spectral approach to numerically integrate the coupled nonlinear partial differential equations of motion in cylindrical geometry in each layer. Version 1.3 implements the special case of two fluid layers of equal resting depths. The flow is forced either by a differentially rotating lid, or by relaxation to specified streamfunction or potential vorticity fields, or both. Dissipation is achieved through Ekman layer pumping and suction at the horizontal boundaries, including the internal interface. The effects of weak interfacial tension are included, as well as the linear topographic beta-effect and the quadratic centripetal beta-effect. Stochastic forcing may optionally be activated, to represent approximately the effects of random unresolved features. A leapfrog time stepping scheme is used, with a Robert filter. Flows simulated by the model agree well with those observed in the corresponding laboratory experiments.
QUAGMIRE v1.3: a quasi-geostrophic model for investigating rotating fluids experiments
NASA Astrophysics Data System (ADS)
Williams, P. D.; Haine, T. W. N.; Read, P. L.; Lewis, S. R.; Yamazaki, Y. H.
2009-04-01
The QUAGMIRE model has recently been made freely available for public use. QUAGMIRE is a quasi-geostrophic numerical model for performing fast, high-resolution simulations of multi-layer rotating annulus laboratory experiments on a desktop personal computer. This presentation describes the model's main features. QUAGMIRE uses a hybrid finite-difference/spectral approach to numerically integrate the coupled nonlinear partial differential equations of motion in cylindrical geometry in each layer. Version 1.3 implements the special case of two fluid layers of equal resting depths. The flow is forced either by a differentially rotating lid, or by relaxation to specified streamfunction or potential vorticity fields, or both. Dissipation is achieved through Ekman layer pumping and suction at the horizontal boundaries, including the internal interface. The effects of weak interfacial tension are included, as well as the linear topographic beta-effect and the quadratic centripetal beta-effect. Stochastic forcing may optionally be activated, to represent approximately the effects of random unresolved features. A leapfrog time stepping scheme is used, with a Robert filter. Flows simulated by the model agree well with those observed in the corresponding laboratory experiments.
QUAGMIRE v1.3: a quasi-geostrophic model for investigating rotating fluids experiments
NASA Astrophysics Data System (ADS)
Williams, P. D.; Haine, T. W. N.; Read, P. L.; Lewis, S. R.; Yamazaki, Y. H.
2009-02-01
QUAGMIRE is a quasi-geostrophic numerical model for performing fast, high-resolution simulations of multi-layer rotating annulus laboratory experiments on a desktop personal computer. The model uses a hybrid finite-difference/spectral approach to numerically integrate the coupled nonlinear partial differential equations of motion in cylindrical geometry in each layer. Version 1.3 implements the special case of two fluid layers of equal resting depths. The flow is forced either by a differentially rotating lid, or by relaxation to specified streamfunction or potential vorticity fields, or both. Dissipation is achieved through Ekman layer pumping and suction at the horizontal boundaries, including the internal interface. The effects of weak interfacial tension are included, as well as the linear topographic beta-effect and the quadratic centripetal beta-effect. Stochastic forcing may optionally be activated, to represent approximately the effects of random unresolved features. A leapfrog time stepping scheme is used, with a Robert filter. Flows simulated by the model agree well with those observed in the corresponding laboratory experiments.
Quasi-periodical variations of pulsars spin as mimicry of differential rotation
NASA Astrophysics Data System (ADS)
Kitiashvili, I.; Gusev, A.
2008-09-01
ABSTRACT Observation of pulsars is a powerful source of information for studying the dynamics and internal structure of neutron stars. Known about quasi-periodical fluctuations of the time-of-arrival of radiation(TOA) for some pulsars, which we explain as Chandler wobble, Free core nutation, Free inner core nutation and Inner core wobble in case three layer model. Using hamilton approximation to theory rotation of multilayer celestial bodies we estimate dynamical flattening for different layers for PSR B1828-11. It is known that an innate feature of pulsar radiation is high stability of the time-of-arrival (TOA) of pulses, and therefore the analysis of TOA fluctuations can reflect subtle effects of neutron stars dynamics. TOA variations of pulsars can be interpreted by three reasons: gravitational perturbation of pulsar by planetary bodies, peculiarities of a pulsar interior like Tkachenko oscillations and free precession motion, when axis of rotation do not coincide with vectors of the angular moment of solid crust, liquid outer core and crystal core. The radial velocity of a star is obtained by measuring the magnitude of the Doppler effect in its spectrum. Stars showing a small amplitude variation of the radial velocity can be interpreted as systems having planetary companions. Assuming that the pulsar PSR B1257+12 has a mass of 1:35M¯, the Keplerian orbital radii are 0.9, 1.4 and 2.1 AU and with masses are 3:1M©=sin(i), 10:2M©=sin(i), 4:6M©=sin(i), where i is the orbital inclination [7]. In 2000, Stairs, Lyne and Shemar reported about their discovery of long-term, highly-periodic and correlated variations of pulse shape and the rate of slow-down of the pulsar PSR B182811 with period variations approximately 1000, 500, 250 and 167 days, which may be a result of the spin axis caused by an asymmetry in the shape of the pulsar. The long-periodic precession phenomenon was also detected for a few pulsars: PSR 2217+47, PSR 0531+21, PSR B083345, PSR B182811, PSR B
NASA Technical Reports Server (NTRS)
Farrell, C. A.
1994-01-01
A computer program, QSONIC, has been developed for calculating the full potential, transonic quasi-three-dimensional flow through a rotating turbomachinery blade row. The need for lighter, more efficient turbomachinery components has led to the consideration of machines with fewer stages, each with blades capable of higher speeds and higher loading. As speeds increase, the numerical problems inherent in the transonic regime have to be resolved. These problems include the calculation of imbedded shock discontinuities and the dual nature of the governing equations, which are elliptic in the subcritical flow regions but become hyperbolic for supersonic zones. QSONIC provides the flow analyst with a fast and reliable means of obtaining the transonic potential flow distribution on a blade-to-blade stream surface of a stationary or rotating turbomachine blade row. QSONIC combines several promising transonic analysis techniques. The full potential equation in conservative form is discretized at each point on a body-fitted period mesh. A mass balance is calculated through the finite volume surrounding each point. Each local volume is corrected in the third dimension for any change in stream-tube thickness along the stream tube. The nonlinear equations for all volumes are of mixed type (elliptic or hyperbolic) depending on the local Mach number. The final result is a block-tridiagonal matrix formulation involving potential corrections at each grid point as the unknowns. The residual of each system of equations is solved along each grid line. At points where the Mach number exceeds unity, the density at the forward (sweeping) edge of the volume is replaced by an artificial density. This method calculates the flow field about a cascade of arbitrary two-dimensional airfoils. Three-dimensional flow is approximated in a turbomachinery blade row by correcting for stream-tube convergence and radius change in the through flow direction. Several significant assumptions were made in
NASA Technical Reports Server (NTRS)
Chao, Winston C.; Chen, Baode; Einaudi, Franco (Technical Monitor)
2000-01-01
Chao's numerical and theoretical work on multiple quasi-equilibria of the intertropical convergence zone (ITCZ) and the origin of monsoon onset is extended to solve two additional puzzles. One is the highly nonlinear dependence on latitude of the "force" acting on the ITCZ due to earth's rotation, which makes the multiple quasi-equilibria of the ITCZ and monsoon onset possible. The other is the dramatic difference in such dependence when different cumulus parameterization schemes are used in a model. Such a difference can lead to a switch between a single ITCZ at the equator and a double ITCZ, when a different cumulus parameterization scheme is used. Sometimes one of the double ITCZ can diminish and only the other remain, but still this can mean different latitudinal locations for the single ITCZ. A single idea based on two off-equator attractors for the ITCZ, due to earth's rotation and symmetric with respect to the equator, and the dependence of the strength and size of these attractors on the cumulus parameterization scheme solves both puzzles. The origin of these rotational attractors, explained in Part I, is further discussed. The "force" acting on the ITCZ due to earth's rotation is the sum of the "forces" of the two attractors. Each attractor exerts on the ITCZ a "force" of simple shape in latitude; but the sum gives a shape highly varying in latitude. Also the strength and the domain of influence of each attractor vary, when change is made in the cumulus parameterization. This gives rise to the high sensitivity of the "force" shape to cumulus parameterization. Numerical results, of experiments using Goddard's GEOS general circulation model, supporting this idea are presented. It is also found that the model results are sensitive to changes outside of the cumulus parameterization. The significance of this study to El Nino forecast and to tropical forecast in general is discussed.
Common oscillations in Global Earth Temperature, Sea Level, and Earth rotation
NASA Astrophysics Data System (ADS)
Zotov, Leonid; Bizouard, Christian; Sidorenkov, Nikolay
2014-05-01
Singular Spectrum Analysis (SSA) of Global Mean Sea Level (GMSL) and Global Average Earth Temperature (HadCRUT4) data after global warming trends subtraction revealed presence of quasi-periodic components with periods of 60, 20 and 10 years in both time series. 60-year component of sea level is anticorrelated with long-periodic changes in temperature, while 10 and 20-year components are correlated. Simultaneous presence of 60-year component in secular Earth rotation rate changes rises a question of interrelations between Earth rotation and Climate. Quasi-20-year changes in GMSL and HadCRUT4 have maxima and minima well corresponding to the amplitude changes of recently reconstructed Chandler wobble excitation, which could be caused by the 18.6-year cycle of the Moon orbital nodes regression. The cause of 10-year oscillations in climate characteristics is enigmatic. It could be related to El Nino variability, Volcanoes, or Solar activity, but correlation with each of those processes found to be small. Looks like it is correlated with 9.3 yr tidal wave.
A quasi-three-dimensional blade surface boundary layer analysis for rotating blade rows
NASA Technical Reports Server (NTRS)
Thompkins, W. T., Jr.; Usab, W. J., Jr.
1981-01-01
A quasi-three-dimensional approximation has been developed for a blade boundary layer which involves the calculation of the effect of nonzero pressure gradients, turbulent flow, and blade twist, but includes only a simple coupling between streamlines. The resulting set of equations is solved using Keller's box scheme. The solution scheme is checked against available incompressible flow solutions and then applied to a NASA low aspect ratio transonic compressor stage for which extensive experimental and computational data are available. It is found that the three-dimensional boundary layer separates significantly sooner and has a much larger influence on rotor performance than would be expected from a two-dimensional analysis.
Modeling and optimization of actively Q-switched Nd-doped quasi-three-level laser
NASA Astrophysics Data System (ADS)
Yan, Renpeng; Yu, Xin; Li, Xudong; Chen, Deying; Gao, Jing
2013-09-01
The energy transfer upconversion and the ground state absorption are considered in solving the rate equations for an active Q-switched quasi-three-level laser. The dependence of output pulse characters on the laser parameters is investigated by solving the rate equations. The influence of the energy transfer upconversion on the pulsed laser performance is illustrated and discussed. By this model, the optimal parameters could be achieved for arbitrary quasi-three-level Q-switched lasers. An acousto-optical Q-switched Nd:YAG 946 nm laser is constructed and the reliability of the theoretical model is demonstrated.
Geometry of Landau Level without Galilean or Rotational Symmetry
NASA Astrophysics Data System (ADS)
Shen, Yu; Haldane, F. D. M.
The integer quantum Hall effect is usually modeled using Galilean-invariant or rotationally-invariant Landau levels. However, these are not generic symmetries of electrons moving in a crystalline background. We explicitly break both symmetries by considering a inversion-symmetric Hamiltonian with quartic terms. We carry out exact diagonalization numerically with a truncated Hilbert space, and define an emergent metric gabn for each Landau level as the expectation value of a bilinear form in momentum. With an appropriate choice of the guiding center coherent state, the Landau level wavefunctions are holomorphic functions of z* times a Gaussian (this is distinct from a well-known property of rotationally-invariant lowest-Landau-level wavefunctions). We show that the zeroes of the wavefunction define a ``topological spin sn'', with its original definition as an ``intrinsic angular momentum'' no longer valid without rotational symmetry. This is now related to the number of zeroes n encircled by the classical orbit by sn = n +1/2 . Finally we introduce a mass tensor mabn for each Landau level using a Lagrangian formalism. We conclude that topological and geometric information can be extracted without resort to Galilean or Rotational symmetries. This work is partly supported by DOE Grant No. DE-SC0002140 and the W. M. Keck Foundation.
Effects of propeller rotation direction on airplane interior noise levels
NASA Technical Reports Server (NTRS)
Willis, C. M.; Mayes, W. H.; Daniels, E. F.
1985-01-01
Interior noise measurements for upsweeping and downsweeping movement of the propeller blade tips past the fuselage were made on a twin-engine airplane and on two simplified fuselage models. Changes in interior noise levels of as much as 8 dB reversal of propeller rotation direction were measured for some configurations and test conditions.
NASA Technical Reports Server (NTRS)
Bonataki, E.; Chaviaropoulos, P.; Papailiou, K. D.
1991-01-01
A new inverse inviscid method suitable for the design of rotating blade sections lying on an arbitrary axisymmetric stream-surface with varying streamtube width is presented. The geometry of the axisymmetric stream-surface and the streamtube width variation with meridional distance, the number of blades, the inlet flow conditions, the rotational speed and the suction and pressure side velocity distributions as functions of the normalized arc-length are given. The flow is considered irrotational in the absolute frame of reference and compressible. The output of the computation is the blade section that satisfies the above data. The method solves the flow equations on a (phi 1, psi) potential function-streamfunction plane for the velocity modulus, W and the flow angle beta; the blade section shape can then be obtained as part of the physical plane geometry by integrating the flow angle distribution along streamlines. The (phi 1, psi) plane is defined so that the monotonic behavior of the potential function is guaranteed, even in cases with high peripheral velocities. The method is validated on a rotating turbine case and used to design new blades. To obtain a closed blade, a set of closure conditions were developed and referred.
Rotational Energies in Various Torsional Levels of CH_2DOH
NASA Astrophysics Data System (ADS)
Coudert, L. H.; Hilali, A. El; Margulès, L.; Motiyenko, R. A.; Klee, S.
2012-06-01
Using an approach accounting for the hindered internal rotation of a monodeuterated methyl group, an analysis of the torsional spectrum of the monodeuterated species of methanol CH_2DOH has been carried out recently and led to the assignment of 76 torsional subbands in its microwave, FIR, and IR spectra. Although this approach also allowed us to account for subband centers, the rotational structure of the torsional subbands is not well understood yet. In this paper, we will deal with the rotational energies of CH_2DOH. Analyses of the rotational structure of the available subbands^b have been performed using the polynomial-type expansion introduced in the case of the normal species of methanol. For each subband, FIR or IR transitions and a-type microwave lines, within the lower torsional level, were fitted. The frequencies of the latters were taken from previous investigations or from new measurements carried out from 50 to 950 GHz with the submillimeterwave solid state spectrometer in Lille. Subbands involving lower levels with v_t=0 and K ≥ 3 could be satisfactorily analyzed. For levels characterized by lower K-values, the expansion fails. In the case of the K=1, v_t=1 level, the frequencies of a-type microwave transitions involving the lower member of the K-type doublet cannot be well reproduced. For K=0 levels with v_t=1 and 2, a large number of terms is needed in the expansion. We will try to understand why the rotational energies of these levels cannot be reproduced. The results of the analyses will be compared to those obtained with a global approach based on the rotation-torsion Hamiltonian of the molecule. [2] El Hilali, Coudert, Konov, and Klee, J. Chem. Phys. 135 (2011) 194309. [3] Ioli, Moruzzi, Riminucci, Strumia, Moraes, Winnewisser, and Winnewisser, J. Mol. Spec. 171 (1995) 130. [4] Quade and Suenram, J. Chem. Phys. 73 (1980) 1127; and Su and Quade, J. Mol. Spec. 134 (1989) 290. [5] Lauvergnat, Coudert, Klee, and Smirnov, J. Mol. Spec. 256 (2009
Conserved Quantities in General Relativity: From the Quasi-Local Level to Spatial Infinity
NASA Astrophysics Data System (ADS)
Chen, Po-Ning; Wang, Mu-Tao; Yau, Shing-Tung
2015-08-01
We define quasi-local conserved quantities in general relativity by using the optimal isometric embedding in Wang and Yau (Commun Math Phys 288(3):919-942, 2009) to transplant Killing fields in the Minkowski spacetime back to the 2-surface of interest in a physical spacetime. To each optimal isometric embedding, a dual element of the Lie algebra of the Lorentz group is assigned. Quasi-local angular momentum and quasi-local center of mass correspond to pairing this element with rotation Killing fields and boost Killing fields, respectively. They obey classical transformation laws under the action of the Poincaré group. We further justify these definitions by considering their limits as the total angular momentum and the total center of mass of an isolated system. These expressions were derived from the Hamilton-Jacobi analysis of the gravitational action and thus satisfy conservation laws. As a result, we obtained an invariant total angular momentum theorem in the Kerr spacetime. For a vacuum asymptotically flat initial data set of order 1, it is shown that the limits are always finite without any extra assumptions. We also study these total conserved quantities on a family of asymptotically flat initial data sets evolving by the vacuum Einstein evolution equation. It is shown that the total angular momentum is conserved under the evolution. For the total center of mass, the classical dynamical formula relating the center of mass, energy, and linear momentum is recovered, in the nonlinear context of initial data sets evolving by the vacuum Einstein evolution equation. The definition of quasi-local angular momentum provides an answer to the second problem in classical general relativity on Penrose's list (Proc R Soc Lond Ser A 381(1780):53-63, 1982).
Tunneling Spectroscopy by Level Matching in the Spin Rotating Frame.
NASA Astrophysics Data System (ADS)
Choi, Changho
In this thesis it is reported how the level-matching NMR in the spin rotating frame can be used to establish the tunneling-state manifold of a methyl group. The energy levels are identified from the spectrum of Zeeman-tunneling level matching resonances where fast CH_3 group population transfers take place. The three -pulse sequence (ABC) used for observing such resonances consists of a spin-locking sequence (AB) followed in ~500 mus by an r.f. pulse C with a comb of pi/2 pulses preceding it. With this new experimental method both the Zeeman to tunneling polarization transfer (during the pulse B) and the reverse transfer (during the pulse C) are detected. The proton Zeeman energy splitting homega_ {rm Z} is varied by changing, point by point, the magnitude of the effective field in the proton nuclear spin rotating frame from a few Gauss to 50 Gauss. The tilt of the effective field in the rotating frame can be set at any angle, from Theta=90^circ (normal rotating frame) to Theta=45 ^circ (45^circ tilted rotating frame). Since dipole-dipole interaction is dependent on tilt, changing the tilt allows us to manipulate the dipole-dipole interaction. In this way the resolution is improved (to better than 10 KHz). In addition the symmetry of the transitions can be identified. This tunneling spectroscopy is limited to tunneling splittings less than ~ 800 KHz. Tunneling spectra of strongly hindered CH _3 torsional oscillator pairs (of methylmalonic acid, dimethyl sulfide, propionic acid and hexane) are reported. The level matching resonances in all these materials were detected at omega_{rm Z}=nomega_{rm T} with n = 1/4, 1/3, 1/2, 2/3 and 1. In one case n = 2 spectral peak was observed. Two noninteracting CH_3 particles manifold, composed of AA, AE and EE states, explains the observed multi-quanta transitions driven by intra- and/or inter-methyl group dipole-dipole interactions to first or second order. Level matching resonances at omega_{rm Z}=2omega _{rm T}/3 and omega
NASA Astrophysics Data System (ADS)
Calkins, M. A.; Marti, P.; Julien, K. A.
2014-12-01
Efforts to understand the dynamics of the Earth's core are hampered by the intrinsic numerical stiffness of the governing equations. It is thought, however, that motions in the core are balanced in the sense that fluid acceleration is subdominant in comparison to the other forces present (Coriolis, pressure, Lorentz, etc.). By exploiting the idea of balanced motions, Busse (J. Fluid Mech., vol. 173, 1986, p. 545) developed a simplified analogue of the Earth's core by restricting the flow to lie within a radially narrow, axially-aligned cylindrical annulus, though the model is limited to motions that are invariant in the direction of the rotation axis and thus outer boundaries that are of small slope. Calkins, Julien and Marti (J. Fluid Mech., vol. 732, 2013, p. 214) extended the two-dimensional annulus model of Busse to three dimensions such that the more physically realistic case of steeply sloping endwalls can be studied. Numerical simulations of this new model show that it can reproduce phenomena that are thought to be present in the Earth's core and other natural systems, such as large-scale vortices and strong zonal jets. We find that the predominantly axially-aligned convective cells that form when the thermal forcing is weak quickly break down into strongly three-dimensional flows as the forcing is increased; the resulting Reynolds stresses lead to axially-aligned mean flows that dominate the kinetic energy spectrum (see figure). Furthermore, this new model has the advantage that it employs physically realistic parameters that are not currently accessible to simulations of the full governing equations.
Paleocene sea level movements with a 430,000 year quasi-periodic cyclicity
Briskin, M. ); Fluegeman, R. )
1990-04-01
Sea level movements with quasi-periodicity of 430,000 years are identified in the marine sedimentary units of the Eastern Gulf Coastal Plain of Mississippi, Alabama and Georgia which represent a 5.8 million year record of strandline displacement during Paleocene time. Principal component analysis of the benthic foraminiferal fauna yielded six assemblages which when combined with two other qualitatively derived assemblages provided paleoecologic information which clearly reflects the influence of paleocirculation and paleoclimatic regime of the Eastern Gulf Coastal Plain. The presence of the planktonic foraminiferal taxa Subbotina trinidadensis and Planorotalites pseudomenardii as well as paleolatitudes ranging from 15{degree} N (for the Campeche Shelf) to 25{degree} N (for the Coastal Plain) emphasizes a paleoclimatic regime which is dominantly tropical. A paleoceanographic model was derived which suggests that normal marine waters were brought into the Gulf of Mexico by two major currents. Strandline displacements are related to transgressive and regressive sea level movements in an ice free Paleocene world. The well delineated 430,000 year quasi-periodic cycle observed in the sea level curve is identified as being astronomical in character. These results support the view that changes in the Earth's orbit may trigger changes in the geometry of the Earth's surface in a way which causes sea level to oscillate with a quasi-periodicity of 430,000 years.
Temperature dependence of quasi-three level laser transition for long pulse Nd:YAG laser
NASA Astrophysics Data System (ADS)
Bidin, Noriah; Pourmand, Seyed Ebrahim; Sidi Ahmad, Muhamad Fakaruddin; Khrisnan, Ganesan; Mohd Taib, Nur Athirah; Nadia Adnan, Nurul; Bakhtiar, Hazri
2013-02-01
The influence of temperature and pumping energy on stimulated emission cross section and the laser output of quasi-three level laser transition are reported. Flashlamp is used to pump Nd:YAG laser rod. Distilled water is mixed with ethylene glycol to vary the temperature of the cooling system between -30 and 60 °C. The capacitor voltage of flashlamp driver is verified to manipulate the input energy within the range of 10-70 J. The line of interest in quasi-three level laser comprised of 938.5 and 946 nm. The stimulated emission cross section of both lines is found to be inversely proportional to the temperature but directly proportional to the input energy. This is attributed from thermal broadening effect. The changes of stimulated emission cross section and the output laser with respect to the temperature and input energy on line 946 nm are realized to be more dominant in comparison to 938.5 nm.
NASA Astrophysics Data System (ADS)
Walker, Kyle M.; Song, L.; Yang, B. H.; Groenenboom, G. C.; van der Avoird, A.; Balakrishnan, N.; Forrey, R. C.; Stancil, P. C.
2015-09-01
Carbon monoxide is a simple molecule present in many astrophysical environments, and collisional excitation rate coefficients due to the dominant collision partners are necessary to accurately predict spectral line intensities and extract astrophysical parameters. We report new quantum scattering calculations for rotational deexcitation transitions of CO induced by H using the three-dimensional potential energy surface (PES) of Song et al. State-to-state cross sections for collision energies from 10-5 to 15,000 cm-1 and rate coefficients for temperatures ranging from 1 to 3000 K are obtained for CO (v = 0, j) deexcitation from j=1-45 to all lower j‧ levels, where j is the rotational quantum number. Close-coupling and coupled-states calculations were performed in full-dimension for j=1-5, 10, 15, 20, 25, 30, 35, 40, and 45 while scaling approaches were used to estimate rate coefficients for all other intermediate rotational states. The current rate coefficients are compared with previous scattering results using earlier PESs. Astrophysical applications of the current results are briefly discussed.
Variability of Rotational Temperatures from Different OH Rovibrational Levels
NASA Astrophysics Data System (ADS)
Vimal, D. V.; Slanger, T. G.
2011-12-01
TThe Meinel band emission lines from rovibrationally excited OH in its electronic ground state in the nightglow are widely used as a diagnostic tool to investigate key mesospheric variables such as temperature, tides, and gravity waves. The OH rotational temperature has been extensively studied to ascertain both long- and short-term variability in the upper atmosphere. Current controversy in the literature regarding the possible variability of temperatures deduced from different OH rovibrational levels limits our ability to compare data from different sources. Researchers tend to use a monitoring vibrational level for OH Meinel bands that is most convenient for their instrument. Background sky spectra captured by astronomical instruments provide detailed records of optical emissions in the upper atmosphere. For this study we utilized existing sky spectra from the Keck telescopes in Mauna Kea and the Very Large Telescope in Chile for the OH Meinel bands bound by the extremes (υ = 3, 8). We compared these results with the temperatures deduced from the O2 0-1 Atmospheric band at 865 nm. This latter emission, emanating from a long-lived species, should represent the true kinetic temperature at the altitude of emission and therefore puts a cap on how high the temperature difference can be between the nominal OH altitude (87 km) and the 95-km altitude of the O2 emission. We present the results of our analysis and discuss the implications for mesospheric temperature retrievals from OH emissions. This work was supported by NSF grant ATM-0924781 from NSF CEDAR.
NASA Astrophysics Data System (ADS)
Geroyannis, Vassilis; Tzelati, Eleftheria
In this paper we compute general-relativistic polytropic models simulating rigidly rotating, pulsating neutron stars. These relativistic compact objects, with a radius of $\\sim 10 \\, \\mathrm{km}$ and mass between $\\sim 1.4$ and $3.2$ solar masses, are closely related to pulsars. We emphasize on computing the change in the pulsation eigenfrequencies owing to a rigid rotation, which, in turn, is a decisive issue for studying stability of such objects. In our computations, we keep rotational perturbation terms of up to second order in the angular velocity.
Quasi-Fermi level splitting and sub-bandgap absorptivity from semiconductor photoluminescence
Katahara, John K.; Hillhouse, Hugh W.
2014-11-07
A unified model for the direct gap absorption coefficient (band-edge and sub-bandgap) is developed that encompasses the functional forms of the Urbach, Thomas-Fermi, screened Thomas-Fermi, and Franz-Keldysh models of sub-bandgap absorption as specific cases. We combine this model of absorption with an occupation-corrected non-equilibrium Planck law for the spontaneous emission of photons to yield a model of photoluminescence (PL) with broad applicability to band-band photoluminescence from intrinsic, heavily doped, and strongly compensated semiconductors. The utility of the model is that it is amenable to full-spectrum fitting of absolute intensity PL data and yields: (1) the quasi-Fermi level splitting, (2) the local lattice temperature, (3) the direct bandgap, (4) the functional form of the sub-bandgap absorption, and (5) the energy broadening parameter (Urbach energy, magnitude of potential fluctuations, etc.). The accuracy of the model is demonstrated by fitting the room temperature PL spectrum of GaAs. It is then applied to Cu(In,Ga)(S,Se){sub 2} (CIGSSe) and Cu{sub 2}ZnSn(S,Se){sub 4} (CZTSSe) to reveal the nature of their tail states. For GaAs, the model fit is excellent, and fitted parameters match literature values for the bandgap (1.42 eV), functional form of the sub-bandgap states (purely Urbach in nature), and energy broadening parameter (Urbach energy of 9.4 meV). For CIGSSe and CZTSSe, the model fits yield quasi-Fermi leveling splittings that match well with the open circuit voltages measured on devices made from the same materials and bandgaps that match well with those extracted from EQE measurements on the devices. The power of the exponential decay of the absorption coefficient into the bandgap is found to be in the range of 1.2 to 1.6, suggesting that tunneling in the presence of local electrostatic potential fluctuations is a dominant factor contributing to the sub-bandgap absorption by either purely electrostatic (screened Thomas-Fermi) or
Soil carbon levels in irrigated Western Corn Belt rotations
Technology Transfer Automated Retrieval System (TEKTRAN)
Proposals promoting the use of massive amounts of crop residues and other lignocellulosic biomass for biofuel production have increased need for evaluation of the sustainability of cropping practices and their effect on environment quality. Our objective was to evaluate the effects of crop rotation ...
The Calculation of Rotational Energy Levels Using Tunneling Hamiltonians
NASA Astrophysics Data System (ADS)
Hougen, Jon T.
2009-06-01
The present talk will present a pedagogical introduction and review of 25 years of using tunneling Hamiltonians to parameterize and fit rotationally resolved spectra of small polyatomic molecules with one or more large-amplitude motions (LAMs). This tunneling formalism does not require a quantitative knowledge of the potential surface, but instead makes use only of its symmetry properties. Topics planned for discussion include: the user communities for such Hamiltonians; the range of applicability and achievable accuracy; a representative list of molecules treated to date and their various combinations of internal-rotation, inversion, hydrogen-bond-exchange, and H-atom-transfer LAMs; a way of organizing the LAMs of these molecules in the mind using the piston-and-crankshaft vocabulary of the reciprocating engine; how the theoretical tools of point-groups, permutation-inversion groups, extended groups, and time reversal are used in the tunneling-Hamiltonian formalism; and finally a brief report on the present status of two unfinished applications of the tunneling-Hamiltonian formalism, namely cis/trans bent acetylene (HCCH) and protonated acetylene (C_2H_3^+).
NASA Astrophysics Data System (ADS)
Kisiel, Zbigniew; Fortman, Sarah; Medvedev, Ivan R.; Winnewisser, Manfred; De Lucia, Frank C.; Koput, Jacek
2010-06-01
The recent studies of the rotational spectrum of the NCNCS molecule demonstrated the success of quantum monodromy in describing the quasilinear behavior of this molecule, inclusive of the abrupt transition of spectroscopic behavior from the bent to the linear molecule regime. Similar, quasisymmetric behaviour, is known to be present in symmetric top molecules, and has been studied at lowest-J transitions for two such molecules, CH_3NCO and CH_3NCS. Further progress requires more experimental data and presently we report FASSST rotational spectra of CH_3NCO and CH_3NCS. The spectra provide practically continuous 117-376 GHz coverage and are very rich, since the ladder of excited vibrational states associated with the qusilinear bending coordinate is multiplied by the nearly free internal rotation of the methyl group. Initial stages of the analysis leading up to an analysis in an extension of the framework used for NCNCS are described. B.P.Winnewisser, et al., Phys. Rev. Lett. 95. 243002 (2005). M.Winnewisser, et al., J. Mol. Struct. 798, 1 {2006}. B.P.Winnewisser, et al., Phys. Chem. Chem. Phys. DOI:10.1039/B922023B (2010). J.Koput, J. Mol. Spectrosc. 115, 131 (1986) J.Koput, J. Mol. Spectrosc. 118, 189 (1986)
NASA Astrophysics Data System (ADS)
Ivanov, Sergey V.
2016-07-01
Stable bimolecular complexes (tightly bound dimers) in the gas phase are usually created during third body stabilization of their unstable precursors-quasi-bound complexes (QCs). The latter can arise under the condition that at least one of the colliding partners has an internal degree of freedom. In this article, the principal difference between "orbitings" and QCs is demonstrated in the classical nonreactive scattering picture. Additionally, fractions of QCs in binary collisions of different linear molecules are compared. Also in the article the influence of QCs on rotational R-T relaxation and on vibration-rotational spectral line broadening is discussed. Explicit formulae shedding light on the QCs contribution to the R-T relaxation cross section and the line width and shift are presented. The obtained results emphasize the need for including QCs in every theoretical modeling of spectroscopic manifestation of intermolecular interactions. Besides the topics above, the possible manifestation of non-impact effects in the central regions of spectral lines due to QCs is stated. And finally, special consideration is given to the problem of adequate simulation of QCs formation at different pressures.
Effects of orientation on the identification of rotated objects depend on the level of identity.
Hamm, J P; McMullen, P A
1998-04-01
Matching names and rotated line drawings of objects showed effects of object orientation that depended on name level. Large effects, in the same range as object naming, were found for rotations between 0 degrees and 120 degrees from upright with subordinate names (e.g., collie), whereas nonsignificant effects were found with superordinate (e.g., animal) and basic names (e.g., dog). These results support image normalization, after contact with orientation-invariant representations, that provide basic-level identity. They consequently fail to support theories of object recognition in which rotated object images are normalized to the upright position before contact with long-term object representations. PMID:9606109
Fluctuations of the Caspian Sea level in the quasi-two-year and 11-year cycles of solar activity
Nuzhdina, M.A.
1995-07-01
Fluctuations of the Caspian Sea level due to dynamics of solar activity in its quasi-two-year and 11-year cycles, as well as to the influence of the 22-to 23-year magnetic cycle are analyzed. Perturbation of the geomagnetic field and the atmospheric circulation are regarded as a transmitting mechanism of the Sun`s influence on the Earth`s hydrosphere.
NASA Astrophysics Data System (ADS)
Rezakhani, Roozbeh; Cusatis, Gianluca
2016-03-01
Discrete fine-scale models, in the form of either particle or lattice models, have been formulated successfully to simulate the behavior of quasi-brittle materials whose mechanical behavior is inherently connected to fracture processes occurring in the internal heterogeneous structure. These models tend to be intensive from the computational point of view as they adopt an "a priori" discretization anchored to the major material heterogeneities (e.g. grains in particulate materials and aggregate pieces in cementitious composites) and this hampers their use in the numerical simulations of large systems. In this work, this problem is addressed by formulating a general multiple scale computational framework based on classical asymptotic analysis and that (1) is applicable to any discrete model with rotational degrees of freedom; and (2) gives rise to an equivalent Cosserat continuum. The developed theory is applied to the upscaling of the Lattice Discrete Particle Model (LDPM), a recently formulated discrete model for concrete and other quasi-brittle materials, and the properties of the homogenized model are analyzed thoroughly in both the elastic and the inelastic regime. The analysis shows that the homogenized micropolar elastic properties are size-dependent, and they are functions of the RVE size and the size of the material heterogeneity. Furthermore, the analysis of the homogenized inelastic behavior highlights issues associated with the homogenization of fine-scale models featuring strain-softening and the related damage localization. Finally, nonlinear simulations of the RVE behavior subject to curvature components causing bending and torsional effects demonstrate, contrarily to typical Cosserat formulations, a significant coupling between the homogenized stress-strain and couple-curvature constitutive equations.
Elevated plasma levels of TIMP-1 in patients with rotator cuff tear
2012-01-01
Background and purpose Extracellular matrix remodeling is altered in rotator cuff tears, partly due to altered expression of matrix metalloproteinases (MMPs) and their inhibitors. It is unclear whether this altered expression can be traced as changes in plasma protein levels. We measured the plasma levels of MMPs and their tissue inhibitors (TIMPs) in patients with rotator cuff tears and related changes in the pattern of MMP and TIMP levels to the extent of the rotator cuff tear. Methods Blood samples were collected from 17 patients, median age 61 (39–77) years, with sonographically verified rotator cuff tears (partial- or full-thickness). These were compared with 16 age- and sex-matched control individuals with sonographically intact rotator cuffs. Plasma levels of MMPs and TIMPs were measured simultaneously using Luminex technology and ELISA. Results The plasma levels of TIMP-1 were elevated in patients with rotator cuff tears, especially in those with full-thickness tears. The levels of TIMP-1, TIMP-3, and MMP-9 were higher in patients with full-thickness tears than in those with partial-thickness tears, but only the TIMP-1 levels were significantly different from those in the controls. Interpretation The observed elevation of TIMP-1 in plasma might reflect local pathological processes in or around the rotator cuff, or a genetic predisposition in these patients. That the levels of TIMP-1 and of certain MMPs were found to differ significantly between partial and full-thickness tears may reflect the extent of the lesion or different etiology and pathomechanisms. PMID:23043271
Rotation vibration energy level clustering in the XB1 ground electronic state of PH2
NASA Astrophysics Data System (ADS)
Yurchenko, S. N.; Thiel, W.; Jensen, Per; Bunker, P. R.
2006-10-01
We use previously determined potential energy surfaces for the Renner-coupled XB1 and AA1 electronic states of the phosphino (PH 2) free radical in a calculation of the energies and wavefunctions of highly excited rotational and vibrational energy levels of the X˜ state. We show how spin-orbit coupling, the Renner effect, rotational excitation, and vibrational excitation affect the clustered energy level patterns that occur. We consider both 4-fold rotational energy level clustering caused by centrifugal distortion, and vibrational energy level pairing caused by local mode behaviour. We also calculate ab initio dipole moment surfaces for the X˜ and A˜ states, and the X˜-A˜ transition moment surface, in order to obtain spectral intensities.
Habacha, Hamdi; Lejeune-Poutrain, Laure; Margas, Nicolas; Molinaro, Corinne
2014-10-01
A recent set of studies has investigated the selective effects of particular physical activities that require full-body rotations, such as gymnastics and wrestling (Moreau, Clerc, Mansy-Dannay, & Guerrien, 2012; Steggemann, Engbert, & Weigelt, 2011), and demonstrated that practicing these activities imparts a clear advantage in in-plane body rotation performance. Other athletes, such as handball and soccer players, whose activities do require body rotations may have more experience with in-depth rotations. The present study examined the effect of two components that are differently solicited in sport practices on the mental rotation ability: the rotation axis (in-plane, in-depth) and the predominantly used limb (arms, legs). Handball players, soccer players, and gymnasts were asked to rotate handball and soccer strike images mentally, which were presented in different in-plane and in-depth orientations. The results revealed that handball and soccer players performed the in-depth rotations faster than in-plane rotations; however, the two rotation axes did not differ in gymnasts. In addition, soccer players performed the mental rotations of handball strike images slower. Our findings suggest that the development of mental rotation tasks that involve the major components of a physical activity allows and is necessary for specifying the links between this activity and the mental rotation performance. PMID:25064695
A diode-pumped Nd3+-doped gadolinium gallium garnet quasi-three-level laser at 933 nm
NASA Astrophysics Data System (ADS)
Liu, J. H.; Han, Y. H.; Zhao, Y. D.
2013-11-01
We report for the first time a Nd3+-doped gadolinium gallium garnet (Nd:GGG) laser operating on a quasi-three-level laser at 933 nm, based on the 4F3/2-4I9/2 transition. Continuous wave 691 mW output power at 933 nm is obtained under 10.2 W of incident pump power. Moreover, intracavity second-harmonic generation has also been achieved with a blue power of 89 mW by using a LiB3O5 (LBO) nonlinear crystal.
NASA Astrophysics Data System (ADS)
Quan, Haiyang; Wu, Fan; Hou, Xi
2015-10-01
New method for reconstructing rotationally asymmetric surface deviation with pixel-level spatial resolution is proposed. It is based on basic iterative scheme and accelerates the Gauss-Seidel method by introducing an acceleration parameter. This modified Successive Over-relaxation (SOR) is effective for solving the rotationally asymmetric components with pixel-level spatial resolution, without the usage of a fitting procedure. Compared to the Jacobi and Gauss-Seidel method, the modified SOR method with an optimal relaxation factor converges much faster and saves more computational costs and memory space without reducing accuracy. It has been proved by real experimental results.
Establishing the level of cylindrical rotation in boxy/peanut bulges
NASA Astrophysics Data System (ADS)
Molaeinezhad, A.; Falcón-Barroso, J.; Martínez-Valpuesta, I.; Khosroshahi, H. G.; Balcells, M.; Peletier, R. F.
2016-02-01
We present SAURON integral-field observations of a sample of 12 mid-to-high-inclination disc galaxies, to unveil hidden bars on the basis of their kinematics, i.e. the correlation between velocity and h3 profiles, and to establish their degree of cylindrical rotation. For the latter, we introduce a method to quantify cylindrical rotation that is robust against inner disc components. We confirm high levels of cylindrical rotation in boxy/peanut bulges, but also observe this feature in a few galaxies with rounder bulges. We suggest that these are also barred galaxies with end-on orientations. Re-analysing published data for our own Galaxy using this new method, we determine that the Milky Way bulge is cylindrically rotating at the same level as the strongest barred galaxy in our sample. Finally, we use self-consistent three-dimensional N-body simulations of bar-unstable discs to study the dependence of cylindrical rotation on the bar's orientation and host galaxy inclination.
On the ro-vibrational energies for the lithium dimer; maximum-possible rotational levels
NASA Astrophysics Data System (ADS)
Mustafa, Omar
2015-03-01
The Deng-Fan potential is used to discuss the reliability of the improved Greene-Aldrich approximation and the factorization recipe of Badawi et al [17] for the central attractive/repulsive core J≤ft( J+1 \\right)/2μ {{r}2}. The factorization recipe is shown to be a more reliable approximation and is used to obtain the rotational-vibrational energies for the {{a}3}Σ u+-7Li2 dimer. For each vibrational state only a limited number of the rotational levels are found to be supported by the {{a}3}Σ u+-7Li2 dimer.
Robust Level Coincidences in the Subband Structure of Quasi 2D Systems
NASA Astrophysics Data System (ADS)
Winkler, R.; Wang, L. Y.; Lin, Y. H.; Chu, C. S.
2011-03-01
Recently, level crossings in the energy bands of crystals have been identified as a key signature for topological phase transitions. In general, three independent parameters must be tuned appropriately to bring two quantum levels into degeneracy. Using realistic models we show that for Bloch electrons in a crystal the parameter space controlling the occurrence of level coincidences has a much richer structure than anticipated previously. In particular, we identify cases where level coincidences depend on only two independent parameters thus making the level coincidences robust, i.e., they cannot be removed by a small perturbation of the Hamiltonian compatible with the crystal symmetry. We consider HgTe/CdTe quantum wells as a specific example. (See arXiv:1011.xxxx) Work supported by Taiwan NSC (Contract No. 99-2112-M-009-006) and a MOE-ATU grant. Work at Argonne supported by DOE BES under Contract No. DE-AC02-06CH11357.
NASA Astrophysics Data System (ADS)
Liu, Yonggang; Peltier, W. Richard
2013-08-01
Preliminary analyses are described of the influence of snowball Earth formation on the rotational state of the Earth as well as its feedback onto relative sea level. We demonstrate that a sufficiently large excess ellipticity of the Earth as might be expected to arise due to the mantle convection process acts to stabilize the rotational axis significantly so that the associated relative sea level change would be negligible. If no such excess ellipticity were characteristic of Neoproterozoic time, then increasing the thickness of the elastic lithosphere significantly promotes true polar wander (TPW) and the associated relative sea level change. On the contrary, increasing the viscosity of the lower mantle has an equally significant but opposite effect. TPW due to ice sheets formation for the 720 Ma and 570 Ma continental configurations (approximate Marinoan) can reach more than 5° and 10° in 10 Myr for viscosity model VM5a, and the associated maximum relative sea level changes at this time reach 26 m and 49 m, respectively. However, if a 1°/Myr TPW due to the action of the mantle convection process is assumed to be superimposed, then these values increase to 70 m and 101 m respectively. Compared to the analyses in which rotational influence is entirely neglected, the probability density distribution of freeboard values obtained here is almost the same except that the tails of the distribution are broadened, making it more difficult to accurately infer continental ice volume during snowball Earth events from observed freeboard changes.
Tunneling spectroscopy by matching energy levels in the spin-rotating frame
NASA Astrophysics Data System (ADS)
Choi, Changho; Pintar, M. M.
1997-09-01
Tunneling spectra of strongly hindered CH3 in methylmalonic acid, dimethyl sulfide, propionic acid, and hexane are reported. The Zeeman-tunneling level-matching resonances are detected at ωZ=nωT, n=14, 13, 12, 23, 1, and 2 when the level matching is maintained for 10 ms in the 54.7° tilted proton spin-rotating frame. A ground-state manifold of two noninteracting but equivalent methyl groups accounts for these spectra. All the transitions, which bring about the population equalization whenever a matching resonance occurs, are driven by time-independent dipole-dipole interactions. The resonance peaks at ωZ=23ωT and ωZ=2ωT, which are observed in a tilted rotating frame only, indicate that pairs of methyl groups undergo a symmetry conversion simultaneously. The calculated magnetization changes, which are the consequence of population equilibration, reproduce the observed resonance peaks intensities well.
Children's physical activity levels during school recess: a quasi-experimental intervention study
Ridgers, Nicola D; Stratton, Gareth; Fairclough, Stuart J; Twisk, Jos WR
2007-01-01
Background Recess provides a daily opportunity for children to engage in moderate-to-vigorous (MVPA) and vigorous physical activity (VPA). Limited research has investigated the effects of recess-based interventions on physical activity using large sample sizes whilst investigating variables that may influence the intervention effect. The aim of the study was to investigate the short-term effects of a playground markings and physical structures intervention on recess physical activity. A secondary aim was to investigate the effects of covariates on the intervention. Methods 150 boys and 147 girls were randomly selected from 26 elementary schools to wear uni-axial accelerometers that quantified physical activity every 5 seconds during recess. Fifteen schools located in deprived areas in one large urban city in England received funding through a national initiative to redesign the playground environment. Eleven schools served as matched socioeconomic controls. Data were collected at baseline and 6-weeks following playground intervention. Recess MVPA and VPA levels adjusted for pupil- and school-level covariates (baseline physical activity, age, gender, recess length, body mass index) were analysed using multilevel analyses. Results Positive but non-significant intervention effects were found for MVPA and VPA when confounding variables were added to the model. Gender was a significant predictor of recess physical activity, with boys engaging in more MVPA and VPA than girls. Significant interactions for MVPA revealed that the intervention effect was stronger for younger elementary aged school children compared to older children, and the intervention effect increased as daily recess duration increased. Conclusion The playground redesign intervention resulted in small but non-significant increases in children's recess physical activity when school and pupil level variables were added to the analyses. Changing the playground environment produced a stronger intervention
The mixed level damping of the single-axial rotation of INS
NASA Astrophysics Data System (ADS)
Wang, Chao; Zhu, Hai; Li, Gang; Gao, Dayuan
2011-12-01
In order to improve the accuracy of the Single-axial Rotation of INS (SRINS), the idea of the level damping of the platform INS is introduced to the system, and the principle of the damping is offered. On the basic of analyzing on both of inner level damping and outer level damping, the mixed level damping is put forward. The results show that by introducing the damping network to the system, both of the Schuler oscillation and the Foucault oscillation are eliminated, and the precision of the SRINS is greatly enhanced; At the same time, by used of the mixed level damping, which can not only reduce the effect of the vehicle power-driven to the precision of the system, but also avoid the limit of the accurate reference velocity.
Denthumdas, Sunil Kumar; Wadgave, Umesh; Pharne, Pooja Mohan; Patil, Sandeep Jambukumar; Kondreddi, Sirisha; Deshpande, Pavan; Koppikar, Rajesh Suresh
2016-01-01
Introduction For any antimicrobial approach to be successful in periodontal therapy, it is important that the antimicrobial agent targets the sub-gingival biofilm by attaining sufficient concentration at the sub-gingival site. Aim The purpose of the present study was to determine and compare the concentrations of ciprofloxacin present in Gingival Crevicular Fluid (GCF) and plasma after its systemic administration. Materials and Methods A total of 20 subjects, in the age group of 30-60 years satisfying the inclusion and exclusion criteria, were chosen from the outpatient Department of Periodontology, Government Dental College and Hospital, Hyderabad and consent was obtained. Subjects were put on oral ciprofloxacin therapy (Baycip, Bayer Corporation) of 500mg twice daily doses for five days to establish steady state tissue levels of the agent. GCF and serum samples were collected at the 72nd hour after the first dose of ciprofloxacin and were compared using unpaired t test. Results The mean gingival index value of the subjects was 1.8 ± 0.59 and the mean probing depth of the subjects taken in the study was 5.724 ± 0.47mm. The results of this study showed that ciprofloxacin concentrations were significantly higher (p<0.001) in GCF than in plasma. Conclusion Results from the present study and those from the earlier studies clearly indicate the ciprofloxacin’s ability to reach and concentrate in infected periodontal sites via GCF. This property of ciprofloxacin may be useful for eradication of periodontal pathogens, thus improving the outcome of periodontal therapy. PMID:27504410
Zeeman-tuned rotational level-crossing spectroscopy in a diatomic free radical.
Cahn, S B; Ammon, J; Kirilov, E; Gurevich, Y V; Murphree, D; Paolino, R; Rahmlow, D A; Kozlov, M G; DeMille, D
2014-04-25
Rotational levels of molecular free radicals can be tuned to degeneracy by using laboratory-scale magnetic fields. Because of their intrinsically narrow width, these level crossings of opposite-parity states have been proposed for use in the study of parity-violating interactions and other applications. We experimentally study a typical manifestation of this system using BaF138. Using a Stark-mixing method for detection, we demonstrate level-crossing signals with spectral width as small as 6 kHz. We use our data to verify the predicted line shapes, transition dipole moments, and Stark shifts and to precisely determine molecular magnetic g factors. Our results constitute an initial proof of concept for use of this system to study nuclear spin-dependent parity-violating effects. PMID:24815646
Lifetimes of Vibro-Rotational Levels in Excited Electronic States of Diatomic Hydrogen Isotopologues
Astashkevich, S. A. Lavrov, B. P.
2015-06-15
The current situation in studies of lifetimes of excited rovibronic levels for the H{sub 2}, D{sub 2}, T{sub 2}, HD, HT, and DT molecules is analyzed. All measured lifetime values (792 entries for 618 different vibro-rotational levels of 33 electronic states) reported in 61 publications before April 2015 are compiled and listed in tabular format together with an annotated bibliography. Experimental data are only available for the H{sub 2}, HD, and D{sub 2} molecules. The data collected in the present work show fragmentariness of experimental data. For the vast majority of the levels, the lifetime values were reported in one paper only and up to now are without independent experimental verification. A complete bibliography of publications concerning semiempirical determination and nonempirical calculations of the lifetimes is presented. Numerical results obtained in the framework of these two approaches are listed only in cases when experimental data are available. For more than half of the levels, the differences between measured and calculated values are three times higher than experimental errors. These discrepancies show necessity of more precise experimental and nonempirical studies. For some 79 rovibronic levels, our analysis makes it possible to propose certain set of recommended lifetime values.
ERIC Educational Resources Information Center
Beste, Christian; Heil, Martin; Konrad, Carsten
2010-01-01
The cognitive process of imaging an object turning around is called mental rotation. Many studies have been put forward analyzing mental rotation by means of event-related potentials (ERPs). Event-related potentials (ERPs) were measured during mental rotation of characters in a sample (N = 82) with a sufficient size to obtain even small effects. A…
NASA Astrophysics Data System (ADS)
O'Brien, Chris; Scully, Marlan O.
2016-01-01
In a straightforward manner, we utilize Floquet theory and adiabatic elimination to derive an analytic expression for a monochromatically driven two-level atom, without making the rotating wave approximation. We show that the counter-rotating terms dropped in the rotating wave approximation are responsible for three major effects. First an ac-Stark phase shift of the driven transition, second increased excited state population from far-detuned driving of the Lorentzian line, and third extra frequencies in the population dynamics that result in "wiggles." The analytic result agrees well with numerical simultations over a wide range of parameters.
Freitag, I.; Henking, R.; Tuennermann, A.; Welling, H.
1995-12-01
Efficient room-temperature operation of a diode-pumped Nd:YAG laser is demonstrated for the quasi-three-level transition at 946 nm. Continuous-wave output powers of more than 800 mW cw in single-frequency operation are generated by application of a composite-cavity nonplanar ring laser. High amplitude and frequency stability of the emitted radiation is observed. {copyright} {ital 1995 Optical Society of America.}
NASA Astrophysics Data System (ADS)
Huang, Jing; Wan, Yuan; Chen, Weibiao
2015-02-01
The influence of temperature and incident pump power on reabsorption loss is theoretically discussed. Temperature characteristic and reabsorption loss rate of a diode-pumped quasi-three-level 946 nm Nd:YAG laser are investigated. Reabsorption effect has a significant impact on laser performance. The results indicate that reabsorption loss increases as the working temperature rises and decreases with the increased incident pump power.
Sträter, H. Brüggemann, R.; Bauer, G. H.; Siol, S.; Klein, A.; Jaegermann, W.
2013-12-21
We have studied chalcocite (Cu{sub 2}S) layers prepared by physical vapor deposition with varying deposition parameters by calibrated spectral photoluminescence (PL) and by confocal PL with lateral resolution of Δ x≈0.9 μm. Calibrated PL experiments as a function of temperature T and excitation fluxes were performed to obtain the absolute PL-yield and to calculate the splitting of the quasi-Fermi levels (QFLs) μ=E{sub f,n}−E{sub f,p} at an excitation flux equivalent to the AM 1.5 spectrum and the absorption coefficient α(ℏω), both in the temperature range of 20 K≤T≤400 K. The PL-spectra reveal two peaks at E{sub #1}=1.17 eV and E{sub #2}=1.3 eV. The samples show a QFL-splitting of μ>700 meV associated with a pseudo band gap of E{sub g}=1.25 eV. The high-energy peak shows an unexpected temperature behavior, namely, an increase of PL-yield with rising temperature at variance with the behavior of QFL-splitting that decreases with rising T. Our observations indicate that, contrary to common believe, it is not the PL-yield, but rather the QFL-splitting that is the comprehensive indicator of the quality of the excited state in an illuminated semiconductor. A further examination of the lateral variation of opto-electronic properties by confocal PL and the surface contour shows no detectable correlation between Cu{sub 2}S grains/grain boundaries and the PL-yield or QFL-splitting.
Acceleration forces at eye level experienced with rotation on the horizontal bar.
Beck, G R; Rabinovitch, P; Brown, A C
1979-06-01
Negative acceleration forces (-Gz) experienced at eye level have been associated with preretinal hemorrhage and headache. These signs and symptoms were found in individuals who experienced negative (toward the head) force while rotating on a horizontal bar or hanging from a trapeze. Lightweight accelerometers were used to measure -Gz experienced at eye level in children and adult gymnasts performing a single-knee backswing on a horizontal bar. Rate of onset of -Gz, peak -Gz, time experiencing -Gz, area of curve (G.second), and mean force (area/time) were calculated. There was no significant difference between the children and the adult gymnasts in any of the above parameters. The best gymnast had a maximum rate of onset of 38.15 G/s and the maximum negative force experienced was 5.52 G. The maximum rate of onset for a child was 41.56 G/s and the maximum negative force experienced was 5.73 G. Compared with -Gz tolerance curves generated on a centrifuge the best gymnast would have become symptomatic while performing this maneuver in 6 s. The best child would have become symptomatic in 25 s. These tolerance limits can be easily exceeded by gymnasts and by the monkey-bar enthusiast. PMID:468634
Mitrovica, Jerry X; Hay, Carling C; Morrow, Eric; Kopp, Robert E; Dumberry, Mathieu; Stanley, Sabine
2015-12-01
In 2002, Munk defined an important enigma of 20th century global mean sea-level (GMSL) rise that has yet to be resolved. First, he listed three canonical observations related to Earth's rotation [(i) the slowing of Earth's rotation rate over the last three millennia inferred from ancient eclipse observations, and changes in the (ii) amplitude and (iii) orientation of Earth's rotation vector over the last century estimated from geodetic and astronomic measurements] and argued that they could all be fit by a model of ongoing glacial isostatic adjustment (GIA) associated with the last ice age. Second, he demonstrated that prevailing estimates of the 20th century GMSL rise (~1.5 to 2.0 mm/year), after correction for the maximum signal from ocean thermal expansion, implied mass flux from ice sheets and glaciers at a level that would grossly misfit the residual GIA-corrected observations of Earth's rotation. We demonstrate that the combination of lower estimates of the 20th century GMSL rise (up to 1990) improved modeling of the GIA process and that the correction of the eclipse record for a signal due to angular momentum exchange between the fluid outer core and the mantle reconciles all three Earth rotation observations. This resolution adds confidence to recent estimates of individual contributions to 20th century sea-level change and to projections of GMSL rise to the end of the 21st century based on them. PMID:26824058
Effects of pairing correlations on the inverse level density parameter of hot rotating nuclei
NASA Astrophysics Data System (ADS)
Thi Quynh Huong, Le; Quang Hung, Nguyen; Thi Quynh Trang, Le
2016-06-01
Angular momentum dependence of the inverse level density parameter K in the excitation-energy region of ∼ 30 – 40 MeV is studied within the finite-temperature Bardeen-Cooper-Schrieffer (FTBCS) theory and the FTBCS theory that includes the effect due to quasiparticle-number fluctuations (FTBCS1). The two theories take into account the noncollective rotation of the nucleus at nonzero values of z-projection M of the total angular momentum. The comparison between the results obtained within the FTBCS and FTBCS1 as well as the case without pairing correlations and the experimental data for two medium-mass even-even nuclei 108Cd and 122Te shows that by including the pairing corrections the FTBCS and FTBCS1 reproduces quite well all the experimental data, whereas the non-pairing case always overestimates the data. Due to the effect of quasiparticle-number fluctuations, the FTBCS1 gaps at different M values do not collapse at critical temperature TC as in the FTBCS ones but monotonously decrease with increasing T and being finite even at high T. As the result, the values of K obtained within the FTBCS1 are always closer to the experimental data than those obtained within the FTBCS.
NASA Astrophysics Data System (ADS)
Egorov, O. V.; Voitsekhovskaya, O. K.; Kashirskii, D. E.
2015-11-01
The intensities of water vapor in the range of pure rotational transitions were calculated up to high quantum numbers (Jmax ~ 30 and Ka max ~ 25). The diagonalization of the effective rotational Hamiltonian, approximated by Pade-Borel method, is applied to obtain the eigenvectors. The centrifugal distortion perturbations in line intensities were taken into account by the traditional equations for matrix elements of the transformed dipole moment, including eight parameters, and previously developed by authors Pade approximant. Moreover, to conduct the calculations, the rotational wavefunctions of the symmetric rotor molecule were applied. The results were compared with the known theoretical data.
NASA Astrophysics Data System (ADS)
Seyed Ebrahim, Pourmand; Noriah, Bidin; Hazri, Bakhtiar
2012-09-01
The influence of temperature and input energy on the fluorescence emission cross section of Nd3+:YAG crystal is studied. The stimulated emission cross sections of quasi-three-level systems are determined in a temperature range from -30 to 60°C and an input energy range from 18 to 75 J. The cross section is found to be decreased when the temperature and the input energy are increased. This is attributed to the thermal broadening mechanism of the emission line. This study is relevant for the development of laser design.
Earth Rotation and Geoid Constraints Upon The Modern Rate of Global Sea Level Rise
NASA Astrophysics Data System (ADS)
Peltier, W. R.
The explanation for the tide gauge inferred rate of secular sea level rise that has been ongoing over the last century remains enigmatic. Various explanations have been pro- posed for the fact that there is a large shortfall between the sum of the estimates of the steric and small ice sheets and glaciers contributions, respectively 0.6 mm yr-1 and ~0.3 mm yr-1 and the tide gauge inferred rate of ~1.8 mm yr-1( see Douglas and Peltier, Physics Today, March 2002 for a recent discussion). Possible explanations in- clude climate induced melting of the great polar ice sheets on Greenland and Antarc- tica, substantial upwards bias in the tide gauge inferred rates ( Cabanes et al., Science, 2002), or substantial underestimation of the steric rate most recently analysed in de- tail be Levitus and others(Science 2001,2002). Strong arguments exist as to why the second explanation is not likely to be correct. If we accept that the steric and small ice sheets estimates are reliable then we are forced to accept a significant contribution due to the modern day melting of polar ice. Yet the extent to which this contribution could be significant is strongly constrained by Earth rotation observations. I will ad- dress the issue as to how firm these constraints actually are. Grace observations of the time dependent geoid height, a signal which is also contaminated by the GIA process, as are Topex/Poseidon observations, once filtered to remove this effect, are expected to be immensely valuable in resolving the remaining uncertainties.
Fabris, A.R.; Oka, T.
1983-03-15
The technique of four-level microwave double resonance has been applied to the study of rotation-inversion transitions of NH/sub 3/ induced by collisions with various polar molecules. H/sub 2/O, D/sub 2/O, CH/sub 3/OH, CH/sub 3/X and CHX/sub 3/ (X = F, Cl, Br, I), NO, CO, and OCS were used as collision partners. The values of eta = ..delta..I/I observed for many four-level systems which are connected by dipole-type transitions (..delta..J = +- 1, ..delta..K = 0, parity +bold-arrow-left-right-) are given and qualitatively explained taking into account the long-range dipole--dipole interaction and the pattern of rotational energy levels of the collision partners.
NASA Astrophysics Data System (ADS)
Petrov, Sergey V.; Kozlovskii, Borislav M.
2007-06-01
We report and substantiate a method for constructing the rotational energy surface (RES) of a molecule as a pure classical object. For an arbitrary molecule we start from the potential energy surface rather than from a conventional "effective Hamiltonian". The method is used for constructing the RES of the PH 3 molecule in its ground vibrational state. We have used an ab initio potential energy surface [D. Wang, Q. Shi, Q.-S. Zhu, J. Chem. Phys. 112 (2000) 9624-9631; S.N. Yurchenko, M. Carvajal, P. Jensen, F. Herregodts, T.R. Huet, Chem. Phys. 290 (2003) 59-67.]. The shape of the RES is shown not to change for J from 0 to 120. The procedure of quasiclassical quantization of the RES was also undertaken, yielding a set of quasiclassical critical values of the angular momentum. The results explain the structure of quantum rotational energy levels obtained by variational calculations [S.N. Yurchenko, W. Thiel, S. Patchkovskii, P. Jensen, Phys. Chem. Chem. Phys. 7 (2005) 573-582].
Thompson, T.A.; Baedke, S.J. . Indiana Geological Survey)
1994-04-01
Lake Michigan contains numerous former embayments into glacial deposits or bedrock. Many of the embayments contain dunes, spits, and captured lakes, but others contain arcuate strandplains of beach ridges. The strandplains are a geologic record of shoreline behavior and lake-level variation throughout the late Holocene. The larger strandplains show similar long-term patterns of beach-ridge development. The similar patterns are expected because variations in lake level are a primary control on shoreline behavior, and all embayments would have experienced relatively the same lake-level changes. Some variations in the long-term pattern of shoreline development do occur between strandplains. These dissimilarities are primarily a function of different rates of sediment supply to the shoreline of each embayment. Beach-ridge development within embayments can be represented on a rate of water level change versus rate of sediment supply diagram (Curray diagram) as three superimposed ovals on the positive rate of sediment supply side of the diagram. The three stacked ovals represent the three quasi-periodic lake-level variations defined by Thompson (1992) and show the position of the shoreline for a given time within the Curray diagram fields. For shorelines with a high rate of sediment supply, only the 30-year quasi-periodic variation would reach the aggradation line. For shorelines having significantly less sediment supply, rising lake level on the 150- and 600-year variations would force the 30-year oval across the aggradation line and well into the depositional and possibly the erosional transgression fields. Under these conditions erosion would occur that may remove, stack, or at least prevent one or more beach ridges from being developed.
Accuracy level of pointing movements performed during slow passive whole-body rotations.
Bourdin, C; Nougier, V; Bringoux, L; Gauthier, G M; Barraud, P A; Raphel, C
2001-05-01
Seated observers requested to detect low-velocity passive rotations show a high motion-detection threshold. However, when standing on a slowly rotating platform, their equilibrium is preserved, suggesting that cognitive sensing and sensorimotor reactions do not share the same central processes. The present experiments investigated the ability of observers seated on a slowly rotating chair in total darkness to indicate with their hand the position of briefly flashed targets (Experiment 1) and to indicate the subjective horizon with an outstretched arm (Experiment 2) or with a target driven by a joystick (Experiment 3). The overall hypothesis stated that egocentric coding of the position of a target should not be affected by sensing or not-sensing body rotation (Experiment 1), while geocentric positioning may (Experiments 2 and 3). Our data partially supported the hypothesis. Subjects pointed accurately to the memorized targets (Experiment 1), whereas misperception of body orientation was a source of inaccuracy for actions referred to a geocentric frame (Experiments 2 and 3). More interestingly, subjects' perceptions changed as a single, smooth, and monotonic function of tilt, independent of whether the perception of body orientation was present or not. PMID:11374084
Park, G Barratt; Jiang, Jun; Saladrigas, Catherine A; Field, Robert W
2016-04-14
The C̃ (1)B2 state of SO2 has a double-minimum potential in the antisymmetric stretch coordinate, such that the minimum energy geometry has nonequivalent SO bond lengths. However, low-lying levels with odd quanta of antisymmetric stretch (b2 vibrational symmetry) have not previously been observed because transitions into these levels from the zero-point level of the X̃ state are vibronically forbidden. We use IR-UV double resonance to observe the b2 vibrational levels of the C̃ state below 1600 cm(-1) of vibrational excitation. This enables a direct characterization of the vibrational level staggering that results from the double-minimum potential. In addition, it allows us to deperturb the strong c-axis Coriolis interactions between levels of a1 and b2 vibrational symmetry and to determine accurately the vibrational dependence of the rotational constants in the distorted C̃ electronic state. PMID:27083725
Park, G. Barratt; Jiang, Jun; Saladrigas, Catherine A.; Field, Robert W.
2016-04-14
Here, the C 1B2 state of SO2 has a double-minimum potential in the antisymmetric stretch coordinate, such that the minimum energy geometry has nonequivalent SO bond lengths. However, low-lying levels with odd quanta of antisymmetric stretch (b2 vibrational symmetry) have not previously been observed because transitions into these levels from the zero-point level of the X~ state are vibronically forbidden. We use IR-UV double resonance to observe the b2 vibrational levels of the C state below 1600 cm–1 of vibrational excitation. This enables a direct characterization of the vibrational level staggering that results from the double-minimum potential. In addition, itmore » allows us to deperturb the strong c-axis Coriolis interactions between levels of a1 and b2 vibrational symmetry, and to determine accurately the vibrational dependence of the rotational constants in the distorted C electronic state.« less
NASA Astrophysics Data System (ADS)
Park, G. Barratt; Jiang, Jun; Saladrigas, Catherine A.; Field, Robert W.
2016-04-01
The C ˜ 1B2 state of SO2 has a double-minimum potential in the antisymmetric stretch coordinate, such that the minimum energy geometry has nonequivalent SO bond lengths. However, low-lying levels with odd quanta of antisymmetric stretch (b2 vibrational symmetry) have not previously been observed because transitions into these levels from the zero-point level of the X ˜ state are vibronically forbidden. We use IR-UV double resonance to observe the b2 vibrational levels of the C ˜ state below 1600 cm-1 of vibrational excitation. This enables a direct characterization of the vibrational level staggering that results from the double-minimum potential. In addition, it allows us to deperturb the strong c-axis Coriolis interactions between levels of a1 and b2 vibrational symmetry and to determine accurately the vibrational dependence of the rotational constants in the distorted C ˜ electronic state.
Lowest-Landau-level description of a Bose-Einstein condensate in a rapidly rotating anisotropic trap
NASA Astrophysics Data System (ADS)
Fetter, Alexander L.
2007-01-01
A rapidly rotating Bose-Einstein condensate in a symmetric two-dimensional trap can be described with the lowest Landau-level set of states. In this case, the condensate wave function ψ(x,y) is a Gaussian function of r2=x2+y2 , multiplied by an analytic function P(z) of the single complex variable z=x+iy ; the zeros of P(z) denote the positions of the vortices. Here, a similar description is used for a rapidly rotating anisotropic two-dimensional trap with arbitrary anisotropy (ωx/ωy⩽1) . The corresponding condensate wave function ψ(x,y) has the form of a complex anisotropic Gaussian with a phase proportional to xy , multiplied by an analytic function P(ζ) , where ζ∝x+iβ-y and 0⩽β-⩽1 is a real parameter that depends on the trap anisotropy and the rotation frequency. The zeros of P(ζ) again fix the locations of the vortices. Within the set of lowest Landau-level states at zero temperature, an anisotropic parabolic density profile provides an absolute minimum for the energy, with the vortex density decreasing slowly and anisotropically away from the trap center.
Vortex lattices in a rotating Fermi superfluid in the BCS-BEC crossover with many Landau levels
Song, Tie-ling; Ma, C.R.; Ma, Yong-li
2012-08-15
We present an explicit analytical analysis of the ground state of vortex lattice structure, based on a minimization of the generalized Gross-Pitaevskii energy functional in a trapped rotating Fermi superfluid gas. By a Bogoliubov-like transformation we find that the coarse-grained average of the atomic density varies as inverted parabola in three dimensional cases; the Fermi superfluid in the BEC regime enters into the lowest Landau level at fast rotation, in which the vortices form an almost regular triangular lattice over a central region and the vortex lattice is expanded along the radial direction in the outer region; the fluid in the unitarity and BCS regimes occupies many low-lying Landau levels, in which a trapped gas with a triangular vortex lattice has a superfluid core surrounded by a normal gas. The calculation is qualitatively consistent with recent numerical and experimental data both in the vortex lattice structure and vortex numbers and in the density profiles versus the stirring frequency in the whole BCS-BEC crossover. - Highlights: Black-Right-Pointing-Pointer We present an analysis of vortex lattice in an interacting trapped rotating Fermi superfluid gas. Black-Right-Pointing-Pointer Decomposing the vortex from the condensate, we can explain the vortex lattice. Black-Right-Pointing-Pointer The calculation is consistent with numerical and experimental data. Black-Right-Pointing-Pointer It can characterize experimentally properties in different regimes of the BCS-BEC crossover.
Courtens, Emilie N P; Boon, Nico; De Clippeleir, Haydée; Berckmoes, Karla; Mosquera, Mariela; Seuntjens, Dries; Vlaeminck, Siegfried E
2014-03-01
With oxygen supply playing a crucial role in an oxygen-limited autotrophic nitrification/denitrification (OLAND) rotating biological contactor (RBC), its controlling factors were investigated in this study. Disc rotation speeds (1.8 and 3.6rpm) showed no influence on the process performance of a lab-scale RBC, although abiotic experiments showed a significant effect on the oxygenation capacity. Estimations of the biological oxygen uptake rate revealed that 85-89% of the oxygen was absorbed by the microorganisms during the air exposure of the discs. Indeed, increasing the disc immersion (50 to 75-80%) could significantly suppress undesired nitratation, on the short and long term. The presented results demonstrated that nitratation could be controlled by the immersion level and revealed that oxygen control in an OLAND RBC should be predominantly based on the atmospheric exposure percentage of the discs. PMID:24457304
NASA Astrophysics Data System (ADS)
Inoue, Tomoyuki; Toprasertpong, Kasidit; Delamarre, Amaury; Watanabe, Kentaroh; Paire, Myriam; Lombez, Laurent; Guillemoles, Jean-François; Sugiyama, Masakazu; Nakano, Yoshiaki
2016-03-01
Insertion of InGaAs/GaAsP strain-balanced multiple quantum wells (MQWs) into i-regions of GaAs p-i-n solar cells show several advantages against GaAs bulk p-i-n solar cells. Particularly under high-concentration sunlight condition, enhancement of the open-circuit voltage with increasing concentration ratio in thin-barrier MQW cells has been reported to be more apparent than that in GaAs bulk cells. However, investigation of the MQW cell mechanisms in terms of I-V characteristics under high-concentration sunlight suffers from the increase in cell temperature and series resistance. In order to investigate the mechanism of the steep enhancement of open-circuit voltage in MQW cells under high-concentration sunlight without affected by temperature, the quasi-Fermi level splitting was evaluated by analyzing electroluminescence (EL) from a cell. Since a cell under current injection with a density Jinjhas similar excess carrier density to a cell under concentrated sunlight with an equivalent short-circuit current Jsc = Jinj, EL measurement with varied Jinj can approximately evaluate a cell performance under a variety of concentration ratio. In addition to the evaluation of quasi-Fermi level splitting, the external luminescence efficiency was also investigated with the EL measurement. The MQW cells showed higher external luminescence efficiency than the GaAs reference cells especially under high-concentration condition. The results suggest that since the MQW region can trap and confine carriers, the localized excess carriers inside the cells make radiative recombination more dominant.
Pure rotational spectrometers for trace-level VOC detection and chemical sensing
NASA Astrophysics Data System (ADS)
Neill, Justin L.; Harris, Brent J.; Pulliam, Robin L.; Muckle, Matt T.; Reynolds, Roger; McDaniel, David; Pate, Brooks H.
2014-05-01
Pure rotational spectroscopy in the centimeter, millimeter, and THz regions of the electromagnetic spectrum is a powerful technique for the characterization of polar molecules in the gas phase. Although this technology has a long history in the research sector for structural characterization, recent advances in digital electronics have only recently made commercial instruments competitive with established chemical analysis techniques. BrightSpec is introducing a platform of pure rotational spectrometers in response to critical unmet needs in chemical analysis. These instruments aim to deliver the operational simplicity of Fourier transform infrared spectrometers in conjunction with the chemical analysis capabilities of mass spectrometers. In particular, the BrightSpec ONE instrument a broadband gas mixture analyzer with full capabilities for chemical analysis. This instrument implements Fourier transform millimeter-wave emission spectroscopy, wherein a brief excitation pulse is applied to the sample, followed by the measurement of the coherent free induction decay responses of all molecular transitions within the excitation bandwidth. After sample injection and characterization, the spectrometer returns a list of all known species detected in the sample, along with their concentrations in the mixture. No prior knowledge about the sample composition is required. The instrument can then perform double-resonance measurements (analogous to 2-D COSY NMR), direct mass determination through analysis of the time profile of the molecular signal, and automated isotopic identification as part of a suite of tools that can return the structural identity of the unknowns in the sample.
Miclaus, Simona; Bechet, Paul; Stratakis, Dimitrios
2014-12-01
With the development of radiofrequency technology, radiating quasi-stochastic signals like the wireless local area networks (WLAN), a proper procedure of exposure level assessment is needed. No standardised procedure exists at the moment. While channel power measurement proved to overestimate the field strength, weighting techniques were proposed. The paper compares the exposure levels determined by three different procedures, two of them correcting the field level by weighting. Twenty-three experimental cases of WLAN traffic load are analysed in an indoor environment in controlled conditions. The results show the differences obtained when the duty cycle (DC) method is applied comparatively with the application of weighting based on an amplitude-time correction. Significant exposure level reductions of 52.6-79.2 % from the field determined by frequency domain method and of 36.5-72.8 % from the field determined by the DC weighting method were obtained by time-amplitude method. Specificities of weighting factors probability density functions were investigated and regression analysis was applied for a detailed characterisation of this procedure. PMID:24591729
Fénelon, Karine; Lamboley, Cédric R.H.; Carrier, Nicole
2012-01-01
Experiments were performed to characterize the properties of the intrinsic Ca2+ buffers in the sarcoplasmic reticulum (SR) of cut fibers from frog twitch muscle. The concentrations of total and free calcium ions within the SR ([CaT]SR and [Ca2+]SR) were measured, respectively, with the EGTA/phenol red method and tetramethylmurexide (a low affinity Ca2+ indicator). Results indicate SR Ca2+ buffering was consistent with a single cooperative-binding component or a combination of a cooperative-binding component and a linear binding component accounting for 20% or less of the bound Ca2+. Under the assumption of a single cooperative-binding component, the most likely resting values of [Ca2+]SR and [CaT]SR are 0.67 and 17.1 mM, respectively, and the dissociation constant, Hill coefficient, and concentration of the Ca-binding sites are 0.78 mM, 3.0, and 44 mM, respectively. This information can be used to calculate a variable proportional to the Ca2+ permeability of the SR, namely d[CaT]SR/dt ÷ [Ca2+]SR (denoted release permeability), in experiments in which only [CaT]SR or [Ca2+]SR is measured. In response to a voltage-clamp step to −20 mV at 15°C, the release permeability reaches an early peak followed by a rapid decline to a quasi-steady level that lasts ∼50 ms, followed by a slower decline during which the release permeability decreases by at least threefold. During the quasi-steady level of release, the release amplitude is 3.3-fold greater than expected from voltage activation alone, a result consistent with the recruitment by Ca-induced Ca2+ release of 2.3 SR Ca2+ release channels neighboring each channel activated by its associated voltage sensor. Release permeability at −60 mV increases as [CaT]SR decreases from its resting physiological level to ∼0.1 of this level. This result argues against a release termination mechanism proposed in mammalian muscle fibers in which a luminal sensor of [Ca2+]SR inhibits release when [CaT]SR declines to a low level
Thompson, T.A.; Baedke, S.J.
1996-01-01
Strandplains of arcuate beach ridges are common in coastal embayments in parts of the Great Lakes. Similarities in beach-ridge development and geomorphology are recognizable in many of the embayments in the Lake Michigan basin despite differences in size and shape, available sediment type and supply, predepositional slope and topography, and hydrographic regime between the embayments. These similarities are primarily a product of three scales of quasiperiodic lake-level variation ranging in time from 30 to 600 years and in water level change from 0.5 to 3.7 m. The interaction of these three lake-level variations can be represented on a Curray (1964) diagram (rate of water level change versus rate of sediment supply). The position of any shoreline on the diagram and the type of behavior the shoreline is experiencing is a product of the interaction of the three variations. Two large Strandplains of late Holocene beach ridges occur at opposite ends of Lake Michigan (Toleston Beach and Thompson embayment). The two areas exhibit similar patterns of beach-ridge development for the past 2600 calendar years. That is, both areas form beach ridges about every 30 years. Groups of 4 to 6 beach ridges reflect a longer-term lake-level variation of about 150 years. Only during the largest variation of about 600 years in duration do the two areas differ. The rise to the 1700 cal yr B.P. high caused the erosion of beach ridges back to 2800 cal yrs B.P. in northern Lake Michigan. In southern Lake Michigan, no erosion occurred during this lake level high. Differences in shoreline development between the two areas are related to the rate of sediment supply to the shorelines. As the sediment sink for the southern half of Lake Michigan, the southern strandplain received a greater sediment flux than the northern strandplain during the latter part of the late Holocene and produced a continuous record of beach-ridge development. ?? 1995 Elsevier Science B.V. All rights reserved.
Quaiser-Pohl, Claudia; Jansen, Petra; Lehmann, Jennifer; Kudielka, Brigitte M
2016-01-01
The consistent gender differences favoring males in some spatial abilities like mental rotation have raised the question of whether testosterone or other gonadal hormones contribute to these differences--especially because such gender differences seem to appear mainly from the age of puberty on. Studies generally suggest that spatial ability is facilitated by moderately high testosterone levels (i.e., levels that are relatively high for females and relatively low for males). However, the role of sex steroids for mental-rotation performance of (pre-) pubertal children has not been the focus of research, yet. In our study, the relationships between different aspects of mental-rotation performance (accuracy, reaction time, rotation speed) and salivary testosterone and estradiol levels were investigated. Subjects were 109 children (51 boys and 58 girls) aged between 9 and 14 years (M = 11.41, SD = 1.74). They performed a chronometric mental-rotations test, in which the stimuli consisted of three-dimensional drawings of Shepard and Metzler cube figures. In addition, saliva samples were gathered for the analysis of free testosterone and estradiol levels. Results showed a significant gender difference in reaction time and rotational speed in favor of boys, and a significant age, but no gender difference in testosterone and estradiol levels. We found no significant relationships between hormonal levels and any measure of mental-rotation performance. PMID:26173010
2011-01-01
The pedicle is a power nucleus of the vertebra and offers a secure grip of all 3 columns. Pedicle screw instrumentation has advantages of rigid fixation with improved three-dimensional (3D) correction and it is accepted as a reliable method with a high margin of safety. Accurate placement of the pedicle screws is important to reduce possible irreversible complications. Many methods of screw insertion have been reported. The author has been using the K-wire method coupled with the intraoperative single posteroanterior and lateral radiographs, which is the most safe, accurate and fast method. Identification of the curve patterns and determining the fusion levels are very important. The ideal classification of adolescent idiopathic scoliosis should address the all patterns, predict the extent of accurate fusion and have good inter/intraobserver reliability. My classification system matches with the ideal classification system, and it is simple and easy to learn; and my classification system has only 4 structural curve patterns and each curve has 2 types. Scoliosis is a 3D deformity; the coronal and sagittal curves can be corrected with rod rotation, and rotational deformity has to be corrected with direct vertebral rotation (DVR). Rod derotation and DVR are true methods of 3D deformity correction with shorter fusion and improved correction of both the fused and unfused curves, and this is accomplished using pedicle screw fixation. The direction of DVR is very important and it should be opposite to the direction of the rotational deformity of the vertebra. A rigid rod has to be used to prevent rod bend-out during the derotation and DVR. PMID:21629468
Accurate Determination of Rotational Energy Levels in the Ground State of ^{12}CH_4
NASA Astrophysics Data System (ADS)
Abe, M.; Iwakuni, K.; Okubo, S.; Sasada, H.
2013-06-01
We have measured absolute frequencies of saturated absorption of 183 allowed and 21 forbidden transitions in the νb{3} band of ^{12}CH_4 using an optical comb-referenced difference-frequency-generation spectrometer from 86.8 to 93.1 THz (from 2890 to 3100 wn). The pump and signal sources are a 1.06-μ m Nd:YAG laser and a 1.5-μ m extended-cavity laser diode. An enhanced-cavity absorption cell increases the optical electric field and enhances the sensitivity. The typical uncertainty is 3 kHz for the allowed transitions and 12 kHz for the forbidden transitions. Twenty combination differences are precisely determined, and the scalar rotational and centrifugal distortion constants of the ground state are thereby yielded as r@ = l@ r@ = l B_{{s}} (157 122 614.2 ± 1.5) kHz, D_{{s}} (3 328.545 ± 0.031) kHz, H_{{s}} (190.90 ± 0.26) Hz, and L_{{s}} (-13.16 ± 0.76) mHz. Here, B_{{s}} is the rotational constant and D_{{s}}, H_{{s}} and L_{{s}} are the scalar quartic, sextic, octic distortion constants. The relative uncertainties are considerably smaller than those obtained from global analysis of Fourier-transform infrared spectroscopy. S. Okubo, H. Nakayama, K. Iwakuni, H. Inaba and H. Sasada, Opt. Express 19, 23878 (2011). M. Abe, K. Iwakuni, S. Okubo, and H. Sasada, J. Opt. Soc. Am. B (to be published). S. Albert, S. Bauerecker, V. Boudon, L. R. Brown, J. -P. Champion, M. Loëte, A. Nikitin, and M. Quack, Chem. Phys. 356, 131 (2009).
Ab initio potential energy surface and vibration-rotation energy levels of silicon dicarbide, SiC2.
Koput, Jacek
2016-10-01
The accurate ground-state potential energy surface of silicon dicarbide, SiC2 , has been determined from ab initio calculations using the coupled-cluster approach. Results obtained with the conventional and explicitly correlated coupled-cluster methods were compared. The core-electron correlation, higher-order valence-electron correlation, and scalar relativistic effects were taken into account. The potential energy barrier to the linear SiCC configuration was predicted to be 1782 cm(-1) . The vibration-rotation energy levels of the SiC2 , (29) SiC2 , (30) SiC2 , and SiC(13) C isotopologues were calculated using a variational method. The experimental vibration-rotation energy levels of the main isotopologue were reproduced to high accuracy. In particular, the experimental energy levels of the highly anharmonic vibrational ν3 mode of SiC2 were reproduced to within 6.7 cm(-1) , up to as high as the v3 = 16 state. PMID:27481562
NASA Astrophysics Data System (ADS)
Underwood, Daniel S.; Yurchenko, Sergei N.; Tennyson, Jonathan; Jensen, Per
2014-06-01
The structure of the purely rotational spectrum of sulphur trioxide 32S16O3 is investigated using a new synthetic line list. The list combines line positions from an empirical model with line intensities determined, in the form of Einstein coefficients, from variationally computed ro-vibrational wavefunctions in conjunction with an ab initio dipole moment surface. The empirical model providing the line positions involves an effective, Watsonian-type rotational Hamiltonian with literature parameter values resulting from least-squares fittings to observed transition frequencies. The formation of so-called 6-fold rotational energy clusters at high rotational excitation are investigated. The SO3 molecule is planar at equilibrium and exhibits a unique type of rotational-energy clustering associated with unusual stabilization axes perpendicular to the S-O bonds. This behaviour is characterized theoretically in the J range from 100-250. The wavefunctions for these cluster states are analysed, and the results are compared to those of a classical analysis in terms of the rotational-energy-surface formalism.
NASA Astrophysics Data System (ADS)
Underwood, Daniel S.; Yurchenko, Sergei N.; Tennyson, Jonathan; Jensen, Per
2014-06-01
The structure of the purely rotational spectrum of sulphur trioxide SO_3 is investigated using a new synthetic line list. The list combines line positions from an empirical model with line intensities determined, in the form of Einstein coefficients, from variationally computed ro-vibrational wavefunctions in conjunction with an ab initio dipole moment surface. The empirical model providing the line positions involves an effective, Watsonian-type rotational Hamiltonian with literature parameter values resulting from least-squares fittings to observed transition frequencies. The formation of so-called rotational energy clusters at high rotational excitation are investigated. The SO_3 molecule is planar at equilibrium and exhibits a unique type of rotational-energy clustering associated with unusual stabilization axes perpendicular to the S--O bonds. This behaviour is characterized theoretically in the J range from 100 through 250. The wavefunctions for these cluster states are analysed, and the results are compared to those of a classical analysis in terms of the rotational-energy-surface formalism.
Role of Serum Fibrinogen Levels in Patients with Rotator Cuff Tears
Longo, Umile Giuseppe; Petrillo, Stefano; Berton, Alessandra; Spiezia, Filippo; Loppini, Mattia; Maffulli, Nicola; Denaro, Vincenzo
2014-01-01
Although rotator cuff (RC) tendinopathy is a frequent pathology of the shoulder, the real understanding of its aetiopathogenesis is still unclear. Several studies showed that RC tendinopathy is more frequent in patients with hyperglycemia, diabetes, obesity, or metabolic syndrome. This paper aims to evaluate the serum concentration of fibrinogen in patients with RC tears. Metabolic disorders have been related to high concentration of serum fibrinogen and the activity of fibrinogen has been proven to be crucial in the development of microvascular damage. Thus, it may produce progression of RC degeneration by reducing the vascular supply of tendons. We report the results of a cross-sectional frequency-matched case-control study comparing the serum concentration of fibrinogen of patients with RC tears with that of a control group of patients without history of RC tears who underwent arthroscopic meniscectomy. We choose to enrol in the control group patients with pathology of the lower limb with a likely mechanic, not metabolic, cause, different from tendon pathology. We found no statistically significant differences in serum concentration of fibrinogen when comparing patients with RC tears and patients who underwent arthroscopic meniscectomy (P = 0.5). Further studies are necessary to clarify the role of fibrinogen in RC disease. PMID:24817887
Calculated rotation-bending energy levels of CH 5+ and a comparison with experiment
NASA Astrophysics Data System (ADS)
Wang, Xiao-Gang; Carrington, Tucker
2016-05-01
We report J > 0 CH 5+ levels computed by fixing stretch coordinates. They are computed by using a simple product basis, exploiting symmetry, and carefully parallelizing the calculation. The J > 0 CH 5+ levels are compared with those obtained from other theoretical methods and with experimental ground state combination differences of Asvany et al. [Science, 347, 1346 (2015)]. If the assignment of Asvany et al. is correct, there are important differences between the levels we compute and those observed. We propose a different assignment of the experimental levels that reduces the maximum error from 34 to 2 cm-1. The new assignment can only be correct if states of both parities exist in the experiment. Although, ro-vibrational levels of CH 5+ cannot be associated with individual vibrational states, they do occur in blocks separated by gaps.
Calculated rotation-bending energy levels of CH5 (+) and a comparison with experiment.
Wang, Xiao-Gang; Carrington, Tucker
2016-05-28
We report J > 0 CH5 (+) levels computed by fixing stretch coordinates. They are computed by using a simple product basis, exploiting symmetry, and carefully parallelizing the calculation. The J > 0 CH5 (+) levels are compared with those obtained from other theoretical methods and with experimental ground state combination differences of Asvany et al. [Science, 347, 1346 (2015)]. If the assignment of Asvany et al. is correct, there are important differences between the levels we compute and those observed. We propose a different assignment of the experimental levels that reduces the maximum error from 34 to 2 cm(-1). The new assignment can only be correct if states of both parities exist in the experiment. Although, ro-vibrational levels of CH5 (+) cannot be associated with individual vibrational states, they do occur in blocks separated by gaps. PMID:27250303
NASA Astrophysics Data System (ADS)
Bignall, Orville Newton
The CH asymmetric stretching region of the methanol spectrum has been measured from 2900 to 3200 cm ^{-1} using the newly constructed Fourier transform spectrometer (FTS). The nominal resolution, the reciprocal of twice the maximum optical path difference, is 0.004 cm^{-1}. The objectives of this investigation were to identify, assign, and analyze the torsion-rovibrational transitions of the CH_3 asymmetric stretching fundamentals v_2 and v_9 . The theory used in the investigation is principally that used by Lees and Baker with the modifications described by Y. Y. Kwan. It is here assumed that this model is suitable for fundamentals other than the torsion rotation. A total of 13 P branch and 11 R branch series were assigned (13 series representing 6 excited states belonging to the v_2 fundamental and 11 series representing 5 excited states belonging to the v_9 fundamental). A partial nonlinear least squares analysis of the series origins yields a band center of 2999.44 cm^{ -1}, a barrier height of 405.62 cm ^{-1}, and a value of 5.29 cm ^{-1} for the moment of inertia of the methyl group about the symmetry axis for the v _2 fundamental. The corresponding values for the v_9 fundamental are 2970.18 cm^{-1}, 529.71 cm ^{-1}, and 5.34 cm^ {-1} respectively. These parameters give a quality of fit with rms deviations of 1.15 cm ^{-1} and 1.26 cm^ {-1} for the v_2 and v_9 bands respectively. A criterion was used to divide the assignments between two separate bands. A comparison between the asymmetric stretch data of methyl fluoride, the OH and CO stretch data of methanol indicates that our assignments are reasonable. Tentative assignments of several series observed in the spectra based on calculations, using the fitted parameters and normal state parallel combination differences, are also given.
NASA Astrophysics Data System (ADS)
Császár, Attila G.; Furtenbacher, T.; Tennyson, Jonathan; Bernath, Peter F.; Brown, Linda R.; Campargue, Alain; Daumont, Ludovic; Gamache, Robert R.; Hodges, Joseph T.; Naumenko, Olga V.; Polyansky, Oleg L.; Rothman, Laurence S.; Vandaele, Ann Carine; Zobov, Nikolai F.
2014-06-01
The results of an IUPAC Task Group formed in 2004 on "A Database of Water Transitions from Experiment and Theory" (Project No. 2004-035-1-100) are presented. Energy levels and recommended labels involving exact and approximate quantum numbers for the main isotopologues of water in the gas phase, H216O, H218O, H217O, HD16O, HD18O, HD17O, D216O, D218O, and D217O, are determined from measured transition wavenumbers. The transition wavenumbers and energy levels are validated using the MARVEL (measured active rotational-vibrational energy levels) approach and first-principles nuclear motion computations. The extensive data, e.g., more than 200,000 transitions have been handled for H216O, including lines and levels that are required for analysis and synthesis of spectra, thermochemical applications, the construction of theoretical models, and the removal of spectral contamination by ubiquitous water lines. These datasets can also be used to assess where measurements are lacking for each isotopologue and to provide accurate frequencies for many yet-to-be measured transitions. The lack of high-quality frequency calibration standards in the near infrared is identified as an issue that has hindered the determination of high-accuracy energy levels at higher frequencies. The generation of spectra using the MARVEL energy levels combined with transition intensities computed using high accuracy ab initio dipole moment surfaces are discussed.
Fujimoto, Takahiro; Imai, Yusuke; Tei, Kazuyoku; Ito, Shinobu; Kanazawa, Hideko; Yamaguchi, Shigeru
2014-01-01
We investigate a technology to create a high temperature heat source on the tip surface of the glass fiber proposed for medical surgery applications. Using 4 to 6 W power level semiconductor lasers at a wavelength of 980 nm, a laser coupled fiber tip was preprocessed to contain a certain amount of titanium oxide powder with a depth of 100 μm from the tip surface so that the irradiated low laser energy could be perfectly absorbed to be transferred to thermal energy. Thus, the laser treatment can be performed without suffering from any optical characteristic of the material. A semiconductor laser was operated quasi-continuous wave mode pulse time duration of 180 ms and >95% of the laser energy was converted to thermal energy in the fiber tip. Based on two-color thermometry, by using a gated optical multichannel analyzer with a 0.25 m spectrometer in visible wavelength region, the temperature of the fiber tip was analyzed. The temperature of the heat source was measured to be in excess 3100 K. PMID:24853040
Uchiyama, Jumpei; Aoki, Shigeru
2015-01-01
To research the detailed mechanism of the lubrication process using the thermal effusivity sensor, the relationships of the lubrication progress with the pattern of powder flow, the rotation speed and the filling level were investigated. The thermal effusivity profile was studied as a function of the number of rotations at various rotation speeds. It was observed that at lower rotation speeds, the profiles of the lubrication progress were almost the same, regardless of the rotation speed. In this region, the highest speed was defined as the critical rotation speed (CRS), which was found to be one of the important factors. The CRS had close relations with avalanche flow in the blender. The first and the second phases were observed in the lubrication process. The first phase was influenced by the CRS and the filling level in the blender. The second phase was influenced by the rotation speed. The mechanism of two-phase process was proposed as a macro progression of the dispersion of the lubricant (first phase) and micro progression of the coating of the powder particles with lubricant (second phase). The accurate monitoring by the thermal effusivity sensor was able to help a better understanding in the lubrication process. PMID:25000482
NASA Astrophysics Data System (ADS)
Delahaye, Thibault; Nikitin, Andrei; Rey, Michaël; Szalay, Péter G.; Tyuterev, Vladimir G.
2014-09-01
In this paper we report a new ground state potential energy surface for ethylene (ethene) C2H4 obtained from extended ab initio calculations. The coupled-cluster approach with the perturbative inclusion of the connected triple excitations CCSD(T) and correlation consistent polarized valence basis set cc-pVQZ was employed for computations of electronic ground state energies. The fit of the surface included 82 542 nuclear configurations using sixth order expansion in curvilinear symmetry-adapted coordinates involving 2236 parameters. A good convergence for variationally computed vibrational levels of the C2H4 molecule was obtained with a RMS(Obs.-Calc.) deviation of 2.7 cm-1 for fundamental bands centers and 5.9 cm-1 for vibrational bands up to 7800 cm-1. Large scale vibrational and rotational calculations for 12C2H4, 13C2H4, and 12C2D4 isotopologues were performed using this new surface. Energy levels for J = 20 up to 6000 cm-1 are in a good agreement with observations. This represents a considerable improvement with respect to available global predictions of vibrational levels of 13C2H4 and 12C2D4 and rovibrational levels of 12C2H4.
NASA Astrophysics Data System (ADS)
Zhu, Chengjie; Deng, L.; Hagley, E. W.
2013-08-01
We investigate linear and nonlinear Faraday effects in a room-temperature, coherently driven four-level active-Raman-gain (ARG) medium. By using the multiple-scale method, we derive two nonlinear coupled envelope equations governing the dynamics of left- and right-polarized components of a linearly polarized probe field. Under the weak probe field approximation, we demonstrate a factor of four increase of the Faraday rotation angle by the linear and nonlinear response of the ARG scheme without probe field loss. We further compare this ARG system with an M-type five-state electromagnetically induced transparency (EIT) scheme and demonstrate the superiority of the ARG scheme over the conventional EIT scheme.
The vibration-rotation-tunneling levels of N2-H2O and N2-D2O
NASA Astrophysics Data System (ADS)
Wang, Xiao-Gang; Carrington, Tucker
2015-07-01
In this paper, we report vibration-rotation-tunneling levels of the van der Waals clusters N2-H2O and N2-D2O computed from an ab initio potential energy surface. The only dynamical approximation is that the monomers are rigid. We use a symmetry adapted Lanczos algorithm and an uncoupled product basis set. The pattern of the cluster's levels is complicated by splittings caused by H-H exchange tunneling (larger splitting) and N-N exchange tunneling (smaller splitting). An interesting result that emerges from our calculation is that whereas in N2-H2O, the symmetric H-H tunnelling state is below the anti-symmetric H-H tunnelling state for both K = 0 and K = 1, the order is reversed in N2-D2O for K = 1. The only experimental splitting measurements are the D-D exchange tunneling splittings reported by Zhu et al. [J. Chem. Phys. 139, 214309 (2013)] for N2-D2O in the v2 = 1 region of D2O. Due to the inverted order of the split levels, they measure the sum of the K = 0 and K = 1 tunneling splittings, which is in excellent agreement with our calculated result. Other splittings we predict, in particular those of N2-H2O, may guide future experiments.
The vibration-rotation-tunneling levels of N2-H2O and N2-D2O.
Wang, Xiao-Gang; Carrington, Tucker
2015-07-14
In this paper, we report vibration-rotation-tunneling levels of the van der Waals clusters N2-H2O and N2-D2O computed from an ab initio potential energy surface. The only dynamical approximation is that the monomers are rigid. We use a symmetry adapted Lanczos algorithm and an uncoupled product basis set. The pattern of the cluster's levels is complicated by splittings caused by H-H exchange tunneling (larger splitting) and N-N exchange tunneling (smaller splitting). An interesting result that emerges from our calculation is that whereas in N2-H2O, the symmetric H-H tunnelling state is below the anti-symmetric H-H tunnelling state for both K = 0 and K = 1, the order is reversed in N2-D2O for K = 1. The only experimental splitting measurements are the D-D exchange tunneling splittings reported by Zhu et al. [J. Chem. Phys. 139, 214309 (2013)] for N2-D2O in the v2 = 1 region of D2O. Due to the inverted order of the split levels, they measure the sum of the K = 0 and K = 1 tunneling splittings, which is in excellent agreement with our calculated result. Other splittings we predict, in particular those of N2-H2O, may guide future experiments. PMID:26178101
Dawadi, Mahesh B; Michael Lindsay, C; Chirokolava, Andrei; Perry, David S; Xu, Li-Hong
2013-03-14
The high-resolution infrared spectrum of methylamine (CH3NH2) has been recorded using slit-jet direct absorption spectroscopy in the ν11 CH-stretch region (2965-3005 cm(-1)) with a resolution of 0.0025 cm(-1). The 621 lines assigned by ground state combination differences represent 27 substates with |K(')| ≤ 2 for the A, B, E1, and E2 symmetries. The spectrum of CH3NH2 is complicated by torsion and inversion tunneling connecting six equivalent minima. The upper states K(') = 0, ± 1 for E1 and E2 are substantially perturbed by "dark" states. The result in the spectrum is multiplets of 2 or 3 states with mixed bright∕dark character. The analysis of the spectrum reveals two qualitative differences in the energy level pattern relative to the vibrational ground state and relative to available data on the lower frequency vibrations (NH2 wag and CN stretch). First at J(') = 0, there is a different ordering of the levels connected by torsion-inversion tunneling. Second, the low-J splittings indicative of torsion-rotation coupling are greatly reduced in the ν11 excited state relative to the vibrational ground state for both the E1 and E2 species, suggesting the partial suppression of torsional tunneling in the ν11 CH-stretch excited state. PMID:23514487
Analysis of the Rotation-Torsion Spectrum of CH_2DOH Within the e_0, e_1, and o_1 Torsional Levels
NASA Astrophysics Data System (ADS)
Coudert, L. H.; Pearson, John C.; Yu, Shanshan; Margules, L.; Motiyenko, R. A.; Klee, S.
2013-06-01
Since the first assignments of Quade and coworkers, a more satisfactory understanding of the spectrum of CH_2DOH has now been achieved. Thanks to a multidimensional potential energy surface and to a new theoretical approach accounting for the internal rotation of a partially deuterated methyl group, 76 torsional subbands could be identified in the microwave and FIR domains. 8356 rotation and rotation-torsion transitions were also assigned for the three lowest lying torsional levels, e_0, e_1, and o_1, in the microwave and terahertz domains and were analyzed with empirical models. In this paper, a new approach aimed at accounting for the rotation-torsion energy levels of CH_2DOH will be presented. It is based on the exact expression of the generalized 4× 4 inertia tensor of the molecule and accounts for the C_s symmetry of the partially deuterated methyl group, for the dependence of the rotational constants on the angle of internal rotation, and for the rotation-torsion Coriolis coupling. This approach will be used to analyze high-resolution data involving the three lowest lying torsional levels, up to k=11. In addition to the microwave data reported recently,^d new transitions recorded in the terahertz domain at JPL will be analyzed. The results of the analysis will be presented in the paper and the parameters determined in the analysis will be discussed. Quade and Suenram, J. Chem. Phys. {73} (1980) 1127; and Su and Quade, J. Mol. Spec. {134} (1989) 290. Lauvergnat, Coudert, Klee, and Smirnov, J. Mol. Spec. {256} (2009) 204. El Hilali, Coudert, Konov, and Klee, J. Chem. Phys. {135} (2011) 194309. Pearson, Yu, and Drouin, J. Mol. Spec. {280} (2012) 119. Quade and Lin, J. Chem. Phys. {38} (1963) 540.
Mitrovica, Jerry X.; Hay, Carling C.; Morrow, Eric; Kopp, Robert E.; Dumberry, Mathieu; Stanley, Sabine
2015-01-01
In 2002, Munk defined an important enigma of 20th century global mean sea-level (GMSL) rise that has yet to be resolved. First, he listed three canonical observations related to Earth’s rotation [(i) the slowing of Earth’s rotation rate over the last three millennia inferred from ancient eclipse observations, and changes in the (ii) amplitude and (iii) orientation of Earth’s rotation vector over the last century estimated from geodetic and astronomic measurements] and argued that they could all be fit by a model of ongoing glacial isostatic adjustment (GIA) associated with the last ice age. Second, he demonstrated that prevailing estimates of the 20th century GMSL rise (~1.5 to 2.0 mm/year), after correction for the maximum signal from ocean thermal expansion, implied mass flux from ice sheets and glaciers at a level that would grossly misfit the residual GIA-corrected observations of Earth’s rotation. We demonstrate that the combination of lower estimates of the 20th century GMSL rise (up to 1990) improved modeling of the GIA process and that the correction of the eclipse record for a signal due to angular momentum exchange between the fluid outer core and the mantle reconciles all three Earth rotation observations. This resolution adds confidence to recent estimates of individual contributions to 20th century sea-level change and to projections of GMSL rise to the end of the 21st century based on them. PMID:26824058
Gómez-Acebo, Inés; Dierssen-Sotos, Trinidad; Papantoniou, Kyriaki; García-Unzueta, María Teresa; Santos-Benito, María Francisca; Llorca, Javier
2015-02-01
The present study aims to compare 6-sulfatoxymelatonin (aMT6s) secretion patterns and levels of cortisol and sex hormones (estradiol, progesterone, DHEA, DHEAS, and testosterone) among rotating night-shift workers and day-shift workers. We performed a cross-sectional study in Cantabria (northern Spain) including 136 women (73 day-shift workers and 63 rotating night-shift workers). Blood and urine samples were obtained after two consecutive working days. Differences in means were estimated using ANCOVA, stratified by menopausal status, ovulation phase, and adjusted for season, age, body mass index, consumption of cigarettes in the last 24 h. aMT6s circadian rhythm was analyzed using the cosinor analysis. The present study showed that rotating night-shift workers had lower excretion of aMT6s than day-shift workers (mesor = 50.26 ng aMT6s/mg creatinine in women with rotating night shift versus 88.79 ng aMT6s/mg creatinine in women with day shift), lower fluctuation (amplitude = 45.24 ng aMT6s/mg creatinine in rotating night-shift workers versus 79.71 ng aMT6s/mg creatinine in day-shift workers), and a later acrophase (aMT6s peak time: 08:31 in rotating night-shift workers versus 07:13 h in day-shift workers). Additionally, women with rotating night shift had higher estradiol and progesterone levels, compared to day workers, especially in the follicular phase on the menstrual cycle. PMID:25216206
Hot water emission spectra: Rotational energy levels of the (0 0 0) and (0 1 0) states of HD17O
NASA Astrophysics Data System (ADS)
Mellau, Georg Ch.; Mikhailenko, Semen N.; Tyuterev, Vladimir G.
2015-02-01
The rotational transitions of the HD17O water isotopologue have been assigned in a high temperature emission spectrum between 320 and 520 cm-1 of water vapor enriched by deuterium and 17O. We assigned 169 emission lines to 189 partly overlapping transitions of pure rotational and the ν2-ν2 rotational bands. A new extended set of 390 rotational energy levels for the (0 0 0) and (0 1 0) vibration states of HD17O up to J = 17 and Ka = 13 was obtained by combination of the new line transitions with those reported in previous studies. We constructed an effective rotational Hamiltonian based on the generation function approach. For this Hamiltonian the deviation between calculated and measured eigenenergies is in the order of 0.001 cm-1. We report a new calculated linelist based on our new energy level list. Our linelist supersedes the IUPAC linelist for the HD17O water isotopologue as it is based on a substantially extended set of accurate transition wavenumbers.
Lee, Yunju; Ashton-Miller, James A
2015-05-01
Whether an arm will buckle under an impulsive end-load should partly depend on the elastic and viscous properties of the pretensed arm muscles. In measuring these properties we hypothesized that neither age, gender, nor muscle pre-contraction level would affect the bilinear elbow or shoulder lumped rotational stiffness or damping parameters in the impulsively end-loaded upper extremity of 38 healthy men and women. Subjects were instructed to preactivate triceps to either 25, 50 or 75% of maximum myoelectric activity levels. Then a standardized impulsive end-load was applied via a 6-axis load cell to the wrist of the slightly flexed arm in the prone posture. Arm kinematic responses were acquired at 280 Hz and an inverse dynamics analysis was used to estimate the bilinear rotational stiffnesses and damping parameters at the elbow and shoulder. The results show that pre-contraction level affected normalized joint rotational stiffness and damping coefficients (p < 0.02). Age affected the initial stiffness for the elbow (p < 0.05), and gender affected that of the shoulder in the sagittal plane (p < 0.006). Arm muscle strength was positively related to normalized stiffness at the elbow, but not the shoulder. We conclude that age, gender and pre-contraction level each affect the viscoelastic behavior of the end-loaded upper extremity in healthy adults. PMID:25395216
NASA Astrophysics Data System (ADS)
Fortenberry, Ryan C.; Lee, Timothy J.; Müller, Holger S. P.
2015-11-01
Silacyclopropynylidene, SiC2, is a known and highly abundant circumstellar molecule. Its spectrum has been established as a major component of lines observed toward the carbon-rich star IRC +10216 (CW Leonis). It has been detected in its low-lying v3 = 1 and 2 vibrational states as well as in various isotopic compositions. Increasing sensitivity and spatial resolution will enable many more emission or absorption lines to be detected. In order to detect new molecular species, unassigned lines of known species must be identified. This work uses established ab initio quartic force fields to produce data necessary for this classification of lines related to SiC2. Agreement between the theoretical vibrational frequencies and known rotational and spectroscopic constants is quite good, as good as 5 cm-1 and 3 MHz, respectively in some cases. In addition, experimentally unknown vibrational frequencies and rotational constants are provided for the first overtones and combination bands in addition to 3ν3, the second overtone of the low-lying antisymmetric stretch/carbide rotation mode. Frequencies of v3 = 3 low-J rotational transitions of the main isotopic species are also estimated from published data for v3 ≤ 2. Further, we determine rotational and centrifugal distortion parameters for which in most cases vibrational effects due to the ν3 mode were reduced to first, and in several cases also to second order. These values may approximate equilibrium values better than the ground state values. The data produced herein will aid in the experimental and observational characterization of this known astromolecule in order to identify some of the unassigned lines for a known entity.
Optimized Quasi-Interpolators for Image Reconstruction.
Sacht, Leonardo; Nehab, Diego
2015-12-01
We propose new quasi-interpolators for the continuous reconstruction of sampled images, combining a narrowly supported piecewise-polynomial kernel and an efficient digital filter. In other words, our quasi-interpolators fit within the generalized sampling framework and are straightforward to use. We go against standard practice and optimize for approximation quality over the entire Nyquist range, rather than focusing exclusively on the asymptotic behavior as the sample spacing goes to zero. In contrast to previous work, we jointly optimize with respect to all degrees of freedom available in both the kernel and the digital filter. We consider linear, quadratic, and cubic schemes, offering different tradeoffs between quality and computational cost. Experiments with compounded rotations and translations over a range of input images confirm that, due to the additional degrees of freedom and the more realistic objective function, our new quasi-interpolators perform better than the state of the art, at a similar computational cost. PMID:26390452
Krüger, Jenny K.; Suchan, Boris
2016-01-01
Aviation security screeners analyze a large number of X-ray images per day and seem to be experts in mentally rotating diverse kinds of visual objects. A robust gender-effect that men outperform women in the Vandenberg & Kuse mental rotation task has been well documented over the last years. In addition it has been shown that training can positively influence the overall task-performance. Considering this, the aim of the present study was to investigate whether security screeners show better performance in the Mental Rotation Test (MRT) independently of gender. Forty-seven security screeners of both sexes from two German airports were examined with a computer based MRT. Their performance was compared to a large sample of control subjects. The well-known gender-effect favoring men on mental rotation was significant within the control group. However, the security screeners did not show any sex differences suggesting an effect of training and professional performance. Surprisingly this specialized group showed a lower level of overall MRT performance than the control participants. Possible aviation related influences such as secondary effects of work-shift or expertise which can cumulatively cause this result are discussed. PMID:27014142
Krüger, Jenny K; Suchan, Boris
2016-01-01
Aviation security screeners analyze a large number of X-ray images per day and seem to be experts in mentally rotating diverse kinds of visual objects. A robust gender-effect that men outperform women in the Vandenberg & Kuse mental rotation task has been well documented over the last years. In addition it has been shown that training can positively influence the overall task-performance. Considering this, the aim of the present study was to investigate whether security screeners show better performance in the Mental Rotation Test (MRT) independently of gender. Forty-seven security screeners of both sexes from two German airports were examined with a computer based MRT. Their performance was compared to a large sample of control subjects. The well-known gender-effect favoring men on mental rotation was significant within the control group. However, the security screeners did not show any sex differences suggesting an effect of training and professional performance. Surprisingly this specialized group showed a lower level of overall MRT performance than the control participants. Possible aviation related influences such as secondary effects of work-shift or expertise which can cumulatively cause this result are discussed. PMID:27014142
Quasi-axially symmetric stellarators
Garabedian, Paul R.
1998-01-01
Confinement of a plasma for controlled thermonuclear fusion is studied numerically. Toroidal equilibria are considered, with an emphasis on the Modular Helias-like Heliac 2 (MHH2), which is a stellarator of low aspect ratio with just two field periods surrounded by 16 modular coils. The geometry is fully three-dimensional, but there is an axial symmetry of the magnetic structure that is calculated to give confinement competitive with that in circular tokamaks. Additional vertical and toroidal field coils, together with a current drive, provide the flexibility and the control of rotational transform necessary for a successful experiment. An MHH3 device with three field periods and comparable quasi-axial symmetry is presented, too, and because of reversed shear, its physical properties may be better. Variational analysis of equilibrium and stability is shown to give a more reliable prediction of performance for these stellarators than linearized or local theories that suffer from a failure of differentiability and convergence. PMID:9707544
Quasi-axially symmetric stellarators.
Garabedian, P R
1998-08-18
Confinement of a plasma for controlled thermonuclear fusion is studied numerically. Toroidal equilibria are considered, with an emphasis on the Modular Helias-like Heliac 2 (MHH2), which is a stellarator of low aspect ratio with just two field periods surrounded by 16 modular coils. The geometry is fully three-dimensional, but there is an axial symmetry of the magnetic structure that is calculated to give confinement competitive with that in circular tokamaks. Additional vertical and toroidal field coils, together with a current drive, provide the flexibility and the control of rotational transform necessary for a successful experiment. An MHH3 device with three field periods and comparable quasi-axial symmetry is presented, too, and because of reversed shear, its physical properties may be better. Variational analysis of equilibrium and stability is shown to give a more reliable prediction of performance for these stellarators than linearized or local theories that suffer from a failure of differentiability and convergence. PMID:9707544
Mantica, P.; Strintzi, D.; Tala, T.; Giroud, C.; Leggate, H.; Sharapov, S.; Vries, P. C. de; Zabeo, L.; Zastrow, K.-D.; Lerche, E.; Van Eester, D.; Peeters, A. G.; Salmi, A.
2009-05-01
Experiments were carried out in the JET tokamak to determine the critical ion temperature inverse gradient length (R/L{sub Ti}=R|{nabla}T{sub i}|/T{sub i}) for the onset of ion temperature gradient modes and the stiffness of T{sub i} profiles with respect to deviations from the critical value. Threshold and stiffness have been compared with linear and nonlinear predictions of the gyrokinetic code GS2. Plasmas with higher values of toroidal rotation show a significant increase in R/L{sub Ti}, which is found to be mainly due to a decrease of the stiffness level. This finding has implications on the extrapolation to future machines of present day results on the role of rotation on confinement.
Generalized quasi variational inequalities
Noor, M.A.
1996-12-31
In this paper, we establish the equivalence between the generalized quasi variational inequalities and the generalized implicit Wiener-Hopf equations using essentially the projection technique. This equivalence is used to suggest and analyze a number of new iterative algorithms for solving generalized quasi variational inequalities and the related complementarity problems. The convergence criteria is also considered. The results proved in this paper represent a significant improvement and refinement of the previously known results.
NASA Astrophysics Data System (ADS)
Tennyson, Jonathan; Bernath, Peter F.; Brown, Linda R.; Campargue, Alain; Császár, Attila G.; Daumont, Ludovic; Gamache, Robert R.; Hodges, Joseph T.; Naumenko, Olga V.; Polyansky, Oleg L.; Rothman, Laurence S.; Vandaele, Ann Carine; Zobov, Nikolai F.; Al Derzi, Afaf R.; Fábri, Csaba; Fazliev, Alexander Z.; Furtenbacher, Tibor; Gordon, Iouli E.; Lodi, Lorenzo; Mizus, Irina I.
2013-03-01
This is the third of a series of articles reporting critically evaluated rotational-vibrational line positions, transition intensities, and energy levels, with associated critically reviewed labels and uncertainties, for all the main isotopologues of water. This paper presents experimental line positions, experimental-quality energy levels, and validated labels for rotational-vibrational transitions of the most abundant isotopologue of water, H216O. The latest version of the MARVEL (Measured Active Rotational-Vibrational Energy Levels) line-inversion procedure is used to determine the rovibrational energy levels of the electronic ground state of H216O from experimentally measured lines, together with their self-consistent uncertainties, for the spectral region up to the first dissociation limit. The spectroscopic network of H216O containstwo components, an ortho (o) and a para (p) one. For o-H216O and p-H216O, experimentally measured, assigned, and labeled transitions were analyzed from more than 100 sources. The measured lines come from one-photon spectra recorded at room temperature in absorption, from hot samples with temperatures up to 3000 K recorded in emission, and from multiresonance excitation spectra which sample levels up to dissociation. The total number of transitions considered is 184 667 of which 182 156 are validated: 68 027 between para states and 114 129 ortho ones. These transitions give rise to 18 486 validated energy levels, of which 10 446 and 8040 belong to o-H216O and p-H216O, respectively. The energy levels, including their labeling with approximate normal-mode and rigid-rotor quantum numbers, have been checked against ones determined from accurate variational nuclear motion computations employing exact kinetic energy operators as well as against previous compilations of energy levels. The extensive list of MARVEL lines and levels obtained are deposited in the supplementary data of this paper, as well as in a distributed information system
NASA Astrophysics Data System (ADS)
Lattanzi, F.; di Lauro, C.; Horneman, V.-M.
The lowest infrared active perpendicular fundamental ν9 of disilane has been analysed on a Fourier transform spectrum between 320 and 430 cm-1, at the spectral resolution of 0.0012 cm-1. The rotation-torsion structure of this band is affected by x,y Coriolis interactions with excited torsional levels of the vibrational ground state, correlating with components of 3ν4 and 4ν4 in the high barrier limit. The interaction of ν9 and 4ν4, forbidden in the D3d symmetry limit, is allowed between components of E torsional symmetry under the G36(EM) extended molecular group, because of the large amplitude of the internal rotation motion. We could determine the values of the main vibration-rotation-torsion parameters of ν9, interaction parameters, and the vibrational wavenumbers of the four torsional components of 3ν4 and of the E3d component of 4ν4. The intrinsic torsional splitting of ν9 is found to be smaller than in the ground vibrational state by 0.0066 cm-1, in good agreement with our theoretical predictions. The possibility of observing the effects of D3d-forbidden interactions in the spectra of ethane-like molecules is also discussed.
Cui, Zhumei; Chen, Yeming; Kong, Xiangzhen; Zhang, Caimeng; Hua, Yufei
2014-02-19
The adsorption of heat-denatured soy proteins at the oil/water (O/W) interface during emulsification was studied. Protein samples were prepared by heating protein solutions at concentrations of 1-5% (w/v) and were then diluted to 0.3% (w/v). The results showed that soy proteins that had been heated at higher concentrations generated smaller droplet size of emulsion. Increase in homogenizer rotating speed resulted in higher protein adsorption percentages and lower surface loads at the O/W interface. Surface loads for both unheated and heated soy proteins were linearly correlated with the unadsorbed proteins' equilibrium concentration at various rotating speeds. With the rise in NaCl addition level, protein adsorption percentage and surface loads of emulsions increased, whereas lower droplet sizes were obtained at the ionic strength of 0.1 M. The aggregates and non-aggregates displayed different adsorption behaviors when rotating speed or NaCl concentration was varied. PMID:24460091
Sunamura, Ei-Ichiro; Kamei, Takashi; Konno, Hiroki; Tamaoki, Nobuyuki; Hisabori, Toru
2014-03-28
Motor enzymes such as F1-ATPase and kinesin utilize energy from ATP for their motion. Molecular motions of these enzymes are critical to their catalytic mechanisms and were analyzed thoroughly using a single molecule observation technique. As a tool to analyze and control the ATP-driven motor enzyme motion, we recently synthesized a photoresponsive ATP analog with a p-tert-butylazobenzene tethered to the 2' position of the ribose ring. Using cis/trans isomerization of the azobenzene moiety, we achieved a successful reversible photochromic control over a kinesin-microtubule system in an in vitro motility assay. Here we succeeded to control the hydrolytic activity and rotation of the rotary motor enzyme, F1-ATPase, using this photosensitive ATP analog. Subsequent single molecule observations indicated a unique pause occurring at the ATP binding angle position in the presence of cis form of the analog. PMID:24607907
Signorile, Joseph F; Lew, Karen M; Stoutenberg, Mark; Pluchino, Alessandra; Lewis, John E; Gao, Jinrun
2014-09-01
Leg extension (LE) is commonly used to strengthen the quadriceps muscles during training and rehabilitation. This study examined the effects of limb position (POS) and range of motion (ROM) on quadriceps electromyography (EMG) during 8 repetitions (REP) of LE. Twenty-four participants performed 8 LE REP at their 8 repetition maximum with lower limbs medially rotated (TI), laterally rotated (TO), and neutral (NEU). Each REP EMG was averaged over the first, middle, and final 0.524 rad ROM. For vastus medialis oblique (VMO), a REP × ROM interaction was detected (p < 0.02). The middle 0.524 rad produced significantly higher EMG than the initial 0.524 rad for REP 6-8 and the final 0.524 rad produced higher EMG than the initial 0.524 rad for REP 1, 2, 3, 4, 6, and 8 (p ≤ 0.05). For rectus femoris (RF), EMG activity increased across REP with TO generating the greatest activity (p < 0.001). For vastus lateralis (VL), EMG increased across REP (p < 0.001) with NEU and TO EMG increasing linearly throughout ROM and TI activity greatest during the middle 0.524 rad. We conclude that to target the VMO, the optimal ROM is the final 1.047 rad regardless of POS, while maximum EMG for the RF is generated using TO regardless of ROM. In contrast, the VL is maximally activated using TI over the first 1.047 rad ROM or in NEU over the final 0.524 rad ROM. PMID:25148303
Signorile, Joseph F; Lew, Karen; Stoutenberg, Mark; Pluchino, Alessandra; Lewis, John E; Gao, Jinrun
2014-06-30
The leg extension (LE) is commonly used to strengthen the quadriceps muscles during training and rehabilitation. This study examined the effects of limb position (POS) and range of motion (ROM) on quadriceps electromyography (EMG) during 8 repetitions (REP) of LE. Twenty-four participants performed eight LE REP at their 8-repetition maximum with lower limbs medially rotated (TI), laterally rotated (TO), and neutral (NEU). Each REP EMG was averaged over the first, middle, and final 0.524 rad ROM. For vastus medialis oblique (VMO), a REP x ROM interaction was detected (p<0.02). The middle 0.524 rad produced significantly higher EMG than the initial 0.524 rad for REP 6-8 and the final 0.524 rad produced higher EMG than the initial 0.524 rad for REP 1, 2, 3, 4, 6, 8 (p<0.05). For rectus femoris (RF), EMG activity increased across REP with TO generating the greatest activity (p<0.001). For vastus lateralis (VL), EMG increased across REP (p<0.001) with NEU and TO EMG increasing linearly throughout ROM, and TI activity greatest during the middle 0.524 rad. We conclude that to target the VMO the optimal ROM is the final 1.047 rad regardless of POS, while maximum EMG for the RF is generated using TO regardless of ROM. In contrast, the VL is maximally activated using TI over the first 1.047 rad ROM or in NEU over the final 0.524 rad ROM. PMID:24983846
NASA Astrophysics Data System (ADS)
Henry, Alan; Chipman, Richard; Hu, Tsay-Hsin G.
1993-04-01
An efficient simulation has been successfully developed to analyze the dynamics and control of spacecraft comprised of multiple rigid/flexible articulating bodies. The implementation employs a typical order-(N) multi-body dynamic approach coupled with a state-of-the-art symbolic equation optimization algorithm. The simulation has been modified to compute the instantaneous acceleration at any arbitrary location on an orbiting body. Gravity gradient, rotational and aerodynamic accelerations contribute to the total quasi-steady state microgravity environment. The simulation is used to evaluate the microgravity levels within Space Station Freedom to demonstrate the excellent microgravity environment which it can provide for scientific experiments.
NASA Astrophysics Data System (ADS)
Iwasaki, Yumi; Nakamura, Kimihito; Horino, Haruhiko; Kawashima, Shigeto
2014-12-01
Assessing factors that influence groundwater levels such as land use and pumping strategy, is essential to adequately manage groundwater resources. A transient numerical model for groundwater flow with infiltration was developed for the Tedori River alluvial fan (140 km2), Japan. The main water input into the groundwater body in this area is irrigation water, which is significantly influenced by land use, namely paddy and upland fields. The proposed model consists of two models, a one-dimensional (1-D) unsaturated-zone water flow model (HYDRUS-1D) for estimating groundwater recharge and a 3-D groundwater flow model (MODFLOW). Numerical simulation of groundwater flow from October 1975 to November 2009 was performed to validate the model. Simulation revealed seasonal groundwater level fluctuations, affected by paddy irrigation management. However, computational accuracy was limited by the spatiotemporal data resolution of the groundwater use. Both annual groundwater levels and recharge during the irrigation periods from 1975 to 2009 showed long-term decreasing trends. With the decline in rice-planted paddy field area, groundwater recharge cumulatively decreased to 61 % of the peak in 1977. A paddy-upland crop-rotation system could decrease groundwater recharge to 73-98 % relative to no crop rotation.
Crawford, R J; Kearns, M P
2003-10-01
Rotational moulding promises designers attractive economics and a low-pressure process. The benefits of rotational moulding are compared here with other manufacturing methods such as injection and blow moulding. PMID:14603714
Astronomers combined 146 exposures taken by NASA's Hubble SpaceTelescope to make this 73-frame movie of the asteroid Vesta's rotation.Vesta completes a rotation every 5.34 hours.âº Asteroid and...
NASA Astrophysics Data System (ADS)
Yang, Xiaolin; Chen, Yuanquan; Pacenka, Steven; Gao, Wangsheng; Ma, Li; Wang, Guangya; Yan, Peng; Sui, Peng; Steenhuis, Tammo S.
2015-03-01
Water shortage is the major bottleneck that limits sustainable yield of agriculture in the North China Plain. Due to the over-exploitation of groundwater for irrigating the winter wheat-summer maize double cropping systems, a groundwater crisis is becoming increasingly serious. To help identify more efficient and sustainable utilization of the limited water resources, the water consumption and water use efficiency of five irrigated cropping systems were calculated and the effect of cropping systems on groundwater table changes was estimated based on a long term field experiment from 2003 to 2013 in the North China Plain interpreted using a soil-water-balance model. The five cropping systems included sweet potato → cotton → sweet potato → winter wheat-summer maize (SpCSpWS, 4-year cycle), ryegrass-cotton → peanuts → winter wheat-summer maize (RCPWS, 3-year cycle), peanuts → winter wheat-summer maize (PWS, 2-year cycle), winter wheat-summer maize (WS, 1-year cycle), and continuous cotton (Cont C). The five cropping systems had a wide range of annual average actual evapotranspiration (ETa): Cont C (533 mm/year) < SpCSpWS (556 mm/year) < PWS (615 mm/year) < RCPWS (650 mm/year) < WS rotation (734 mm/year). The sequence of the simulated annual average groundwater decline due to the five cropping systems was WS (1.1 m/year) > RCPWS (0.7 m/year) > PWS (0.6 m/year) > SPCSPWS and Cont C (0.4 m/year). The annual average economic output water use efficiency (WUEe) increased in the order SpCSpWS (11.6 yuan ¥ m-3) > RCPWS (9.0 ¥ m-3) > PWS (7.3 ¥ m-3) > WS (6.8 ¥ m-3) > Cont C (5.6 ¥ m-3) from 2003 to 2013. Results strongly suggest that diversifying crop rotations could play a critically important role in mitigating the over-exploitation of the groundwater, while ensuring the food security or boosting the income of farmers in the North China Plain.
Photonic quasi-crystal terahertz lasers
Vitiello, Miriam Serena; Nobile, Michele; Ronzani, Alberto; Tredicucci, Alessandro; Castellano, Fabrizio; Talora, Valerio; Li, Lianhe; Linfield, Edmund H.; Davies, A. Giles
2014-01-01
Quasi-crystal structures do not present a full spatial periodicity but are nevertheless constructed starting from deterministic generation rules. When made of different dielectric materials, they often possess fascinating optical properties, which lie between those of periodic photonic crystals and those of a random arrangement of scatterers. Indeed, they can support extended band-like states with pseudogaps in the energy spectrum, but lacking translational invariance, they also intrinsically feature a pattern of ‘defects’, which can give rise to critically localized modes confined in space, similar to Anderson modes in random structures. If used as laser resonators, photonic quasi-crystals open up design possibilities that are simply not possible in a conventional periodic photonic crystal. In this letter, we exploit the concept of a 2D photonic quasi crystal in an electrically injected laser; specifically, we pattern the top surface of a terahertz quantum-cascade laser with a Penrose tiling of pentagonal rotational symmetry, reaching 0.1–0.2% wall-plug efficiencies and 65 mW peak output powers with characteristic surface-emitting conical beam profiles, result of the rich quasi-crystal Fourier spectrum. PMID:25523102
NASA Technical Reports Server (NTRS)
1988-01-01
The NASA Bioreactor provides a low turbulence culture environment which promotes the formation of large, three-dimensional cell clusters. Due to their high level of cellular organization and specialization, samples constructed in the bioreactor more closely resemble the original tumor or tissue found in the body. NASA-sponsored bioreactor research has been instrumental in helping scientists to better understand normal and cancerous tissue development. In cooperation with the medical community, the bioreactor design is being used to prepare better models of human colon, prostate, breast and ovarian tumors. Cartilage, bone marrow, heart muscle, skeletal muscle, pancreatic islet cells, liver and kidney are just a few of the normal tissues currently being cultured in rotating bioreactors by investigators.
THE QUASI NONGOVERNMENTAL ORGANIZATION.
ERIC Educational Resources Information Center
PIFER, ALAN
ORGANIZED TO MEET URGENT NATIONAL NEEDS, PROVIDE INDEPENDENT JUDGMENT, AND OFFER FRESH SOLUTIONS TO COMPLEX PROBLEMS, THE QUASI NONGOVERNMENTAL ORGANIZATION IS DEFINED AS A NONPROFIT ASSOCIATION OR INSTITUTION LODGED IN THE PRIVATE SECTOR OF SOCIETY BUT FINANCED LARGELY OR ENTIRELY BY THE FEDERAL GOVERNMENT, RESPONSIBLE TO ITS OWN BOARD OF…
Pokhozhaev, Stanislav I
2011-06-30
The notion of Riemann quasi-invariants is introduced and their applications to several conservation laws are considered. The case of nonisentropic flow of an ideal polytropic gas is analysed in detail. Sufficient conditions for gradient catastrophes are obtained. Bibliography: 16 titles.
Counter-rotating accretion discs
NASA Astrophysics Data System (ADS)
Dyda, S.; Lovelace, R. V. E.; Ustyugova, G. V.; Romanova, M. M.; Koldoba, A. V.
2015-01-01
Counter-rotating discs can arise from the accretion of a counter-rotating gas cloud on to the surface of an existing corotating disc or from the counter-rotating gas moving radially inwards to the outer edge of an existing disc. At the interface, the two components mix to produce gas or plasma with zero net angular momentum which tends to free-fall towards the disc centre. We discuss high-resolution axisymmetric hydrodynamic simulations of viscous counter-rotating discs for the cases where the two components are vertically separated and radially separated. The viscosity is described by an isotropic α-viscosity including all terms in the viscous stress tensor. For the vertically separated components, a shear layer forms between them and the middle part of this layer free-falls to the disc centre. The accretion rates are increased by factors of ˜102-104 over that for a conventional disc rotating in one direction with the same viscosity. The vertical width of the shear layer and the accretion rate are strongly dependent on the viscosity and the mass fraction of the counter-rotating gas. In the case of radially separated components where the inner disc corotates and the outer disc rotates in the opposite direction, a gap between the two components opens and closes quasi-periodically. The accretion rates are ≳25 times larger than those for a disc rotating in one direction with the same viscosity.
NASA Technical Reports Server (NTRS)
Koker, Edmond B.
1995-01-01
The importance of the OH radical as an intermediate in many combustion reactions and in atmospheric photochemistry has led many researchers to use it as a diagnostic tool in these processes. The amount of data that has been acquired over the years for this radical is quite considerable. However, the quenching rate of OH with water molecules as a function of temperature and the rotational level of the excited state is not very well understood. The motivation of the studies undertaken is to bridge the gap between the low temperature measurements and the high temperature ones reported in the literature. The technique generally employed in these diagnostics is laser-induced fluorescence (LIF), through which rotational state selective excitation of the radical is possible. Furthermore, in a combustion medium, water is produced in abundance so that knowledge of the quenching rate of OH due to water molecules plays a crucial role in interpreting the data. In general, the precursor to an understanding of the collisional quenching rates of OH involves a characterization of the mode in which the radical is produced; the resulting rotational and translational distribution, followed by a measurement of the OH temperature; and ultimately obtaining the rate constants from the pressure dependence of the fluorescence signal. The experimental implementation of these measurements therefore involved, as a first step, the production of the OH radicals in a microwave discharge cell using water vapor as the source, wherein a hydrogen atom is abstracted from H2O. The second step involved the absorption of photons from the frequency-doubled output of a pulsed amplified, single-frequency cw ring dye laser. By tuning the laser to the peak of the transition and observing the fluorescence decay after the laser pulse, the lifetime of the OH in a particular rotational electronic state was determined (tau = 1.4 microseconds for Q(sub 1)(3)). Knowledge of this parameter led to a determination of
NASA Astrophysics Data System (ADS)
Huang, Hong-Yi; Tsai, Ming-Tsang; Lin, King-Chuen
2006-04-01
With photolysis-probe technique, we have studied vibrational and rotational energy transfers of CH involving the B Σ-2 (v =1, 0⩽N⩽6, F) state by collisions with Ar, CO, and N2O. For the vibrational energy transfer (VET) measurements, the time-resolved fluorescence of the B-X(0,0) band is monitored following the (1,0) band excitation. For the rotational energy transfer (RET) measurements, the laser-induced fluorescence of the initially populated state is dispersed using a step-scan Fourier transform spectrometer. The time-resolved spectra obtained in the nanosecond regime may yield the RET information under a single pressure of the collider. The rate constants of intramolecular energy transfers are evaluated with simulation of kinetic models. The VET lies in the range of 4×10-12to4×10-11cm3molecule-1s-1, with efficiency following the order of Ar
NASA Astrophysics Data System (ADS)
Fries, Christian; Weitz, Marco; Theobald, Christian; v. Löwis of Menar, Patric; Bartschke, Jürgen; L'huillier, Johannes A.
2015-02-01
With the advent of high power and narrow bandwidth 969 nm pump diodes, direct pumping into the upper laser level of Yb:YAG and hence quasi-2-level lasers became possible. Pumping directly into the emitting level leads to higher quantum efficiency and reduction of non-radiative decay. Consequently, thermal load, thermal lensing and risk of fracture are reduced significantly. Moreover pump saturation and thermal population of uninvolved energy-levels in ground and excited states are benefical for a homogenous distribution of the pump beam as well as the reduction of reabsorption loss compared to 3-level systems, which allows for high-power DPSS lasers. Beside continuous-wave (cw) operation, nanosecond pulses with a repetition rate between 1 and 5 kHz are an attractive alternative to flashlamp-pumped systems (10-100 Hz) in various measurement applications that require higher data acquisition rates because of new faster detectors. Based on measurements of the absorption and a detailed numerical model for pump beam distribution, including beam propagation and saturation factors, power-scaling of a ceramic rod Yb:YAG oscillator was possible. Finally a cw output power of 50 W with 33 % pump efficiency at 1030 nm has been demonstrated (M2 < 1.2). Nanosecond pulses have been produced by cavity-dumping of this system. The cavity-dumped setup allowed for 3-10 ns pulses with a pulse energy of 12.5 mJ at 1 kHz (M2 < 1.1). In order to achieve these results a systematic experimental and numerical investigation on gain dynamics and the identification of different stable operating regimes has been carried out.
NASA Technical Reports Server (NTRS)
Wahr, John
1993-01-01
The work done under NASA grant NAG5-485 included modelling the deformation of the earth caused by variations in atmospheric pressure. The amount of deformation near coasts is sensitive to the nature of the oceanic response to the pressure. The PSMSL (Permanent Service for Mean Sea Level) data suggest the response is inverted barometer at periods greater than a couple months. Green's functions were constructed to describe the perturbation of the geoid caused by atmospheric and oceanic loading and by the accompanying load-induced deformation. It was found that perturbation of up to 2 cm are possible. Ice mass balance data was used for continental glaciers to look at the glacial contributions to time-dependent changes in polar motion, the lod, the earth's gravitational field, the position of the earth's center-of-mass, and global sea level. It was found that there can be lateral, non-hydrostatic structure inside the fluid core caused by gravitational forcing from the mantle, from the inner core, or from topography at the core/mantle or inner core/outer core boundaries. The nutational and tidal response of a non-hydrostatic earth with a solid inner core was modeled. Monthly, global tide gauge data from PSMSL was used to look at the 18.6-year ocean tide, the 14-month pole tide, the oceanic response to pressure, the linear trend and inter-annual variability in the earth's gravity field, the global sea level rise, and the effects of post glacial rebound. The effects of mantle anelasticity on nutations, earth tides, and tidal variation in the lod was modeled. Results of this model can be used with Crustal Dynamics observations to look at the anelastic dissipation and dispersion at tidal periods. The effects of surface topography on various components of crustal deformation was also modeled, and numerical models were developed of post glacial rebound.
NASA Astrophysics Data System (ADS)
Wahr, John
1993-03-01
The work done under NASA grant NAG5-485 included modelling the deformation of the earth caused by variations in atmospheric pressure. The amount of deformation near coasts is sensitive to the nature of the oceanic response to the pressure. The PSMSL (Permanent Service for Mean Sea Level) data suggest the response is inverted barometer at periods greater than a couple months. Green's functions were constructed to describe the perturbation of the geoid caused by atmospheric and oceanic loading and by the accompanying load-induced deformation. It was found that perturbation of up to 2 cm are possible. Ice mass balance data was used for continental glaciers to look at the glacial contributions to time-dependent changes in polar motion, the lod, the earth's gravitational field, the position of the earth's center-of-mass, and global sea level. It was found that there can be lateral, non-hydrostatic structure inside the fluid core caused by gravitational forcing from the mantle, from the inner core, or from topography at the core/mantle or inner core/outer core boundaries. The nutational and tidal response of a non-hydrostatic earth with a solid inner core was modeled. Monthly, global tide gauge data from PSMSL was used to look at the 18.6-year ocean tide, the 14-month pole tide, the oceanic response to pressure, the linear trend and inter-annual variability in the earth's gravity field, the global sea level rise, and the effects of post glacial rebound. The effects of mantle anelasticity on nutations, earth tides, and tidal variation in the lod was modeled. Results of this model can be used with Crustal Dynamics observations to look at the anelastic dissipation and dispersion at tidal periods. The effects of surface topography on various components of crustal deformation was also modeled, and numerical models were developed of post glacial rebound.
Simulation of Non-resonant Internal Kink Mode with Toroidal Rotation in NSTX
Fu, Guoyong
2013-07-16
Plasmas in spherical and conventional tokamaks, with weakly reversed shear q pro le and minimum q above but close to unity, are susceptible to an non-resonant (m, n ) = (1, 1) internal kink mode. This mode can saturate and persist and can induce a (2; 1) seed island for Neoclassical Tearing Mode (NTMs)1 . The mode can also lead to large energetic particle transport and signi cant broadening of beam-driven current. Motivated by these important e ects, we have carried out extensive nonlinear simulations of the mode with nite toroidal rotation using parameters and pro les of an NTSX plasma with a weakly reversed shear pro le. The numerical results show that, at the experimental level, plasma rotation has little e ect on either equilibrium or linear stability. However, rotation can signi cantly inuence the nonlinear dynamics of the (1, 1) mode and the the induced (2, 1) magnetic island. The simulation results show that a rotating helical equilibrium is formed and maintained in the nonlinear phase at nite plasma rotation. In contrast, for non-rotating cases, the nonlinear evolution exhibits dynamic oscillations between a quasi-2D state and a helical state. Furthermore, the e ects of rotation are found to greatly suppress the (2, 1) magnetic island even at a low level.
Arthroscopic rotator cuff repair.
Burkhart, Stephen S; Lo, Ian K Y
2006-06-01
Arthroscopic rotator cuff repair is being performed by an increasing number of orthopaedic surgeons. The principles, techniques, and instrumentation have evolved to the extent that all patterns and sizes of rotator cuff tear, including massive tears, can now be repaired arthroscopically. Achieving a biomechanically stable construct is critical to biologic healing. The ideal repair construct must optimize suture-to-bone fixation, suture-to-tendon fixation, abrasion resistance of suture, suture strength, knot security, loop security, and restoration of the anatomic rotator cuff footprint (the surface area of bone to which the cuff tendons attach). By achieving optimized repair constructs, experienced arthroscopic surgeons are reporting results equal to those of open rotator cuff repair. As surgeons' arthroscopic skill levels increase through attendance at surgical skills courses and greater experience gained in the operating room, there will be an increasing trend toward arthroscopic repair of most rotator cuff pathology. PMID:16757673
Quasi-critical orbits for artificial lunar satellites
NASA Astrophysics Data System (ADS)
Tzirti, S.; Tsiganis, K.; Varvoglis, H.
2009-07-01
We study the problem of critical inclination orbits for artificial lunar satellites, when in the lunar potential we include, besides the Keplerian term, the J 2 and C 22 terms and lunar rotation. We show that, at the fixed points of the 1-D averaged Hamiltonian, the inclination and the argument of pericenter do not remain both constant at the same time, as is the case when only the J 2 term is taken into account. Instead, there exist quasi-critical solutions, for which the argument of pericenter librates around a constant value. These solutions are represented by smooth curves in phase space, which determine the dependence of the quasi-critical inclination on the initial nodal phase. The amplitude of libration of both argument of pericenter and inclination would be quite large for a non-rotating Moon, but is reduced to <0°.1 for both quantities, when a uniform rotation of the Moon is taken into account. The values of J 2, C 22 and the rotation rate strongly affect the quasi-critical inclination and the libration amplitude of the argument of pericenter. Examples for other celestial bodies are given, showing the dependence of the results on J 2, C 22 and rotation rate.
ERIC Educational Resources Information Center
Lekner, John
2008-01-01
Any free-particle wavepacket solution of Schrodinger's equation can be converted by differentiations to wavepackets rotating about the original direction of motion. The angular momentum component along the motion associated with this rotation is an integral multiple of [h-bar]. It is an "intrinsic" angular momentum: independent of origin and…
The Trend of "Quasi-Religiosity" among Krasnoiarsk College Students
ERIC Educational Resources Information Center
Nemirovskii, V. G.; Starikov, P. A.
2005-01-01
This article is devoted to a study of the structure and dynamics of "quasi-religious" ideas in the everyday consciousness of Russian college students. What is meant by the term quasi-religiosity is a whole set of unsystematized ideas, the respondents' belief in idealistic concepts that are popular on the level of mass consciousness. The study's…
Cook, G.T.
1995-12-31
The Packard 2770TR/SL is a novel low-level liquid scintillation spectrometer which employs bismuth germanate (BGO - Bi{sub 4}Ge{sub 3}O{sub 12}) as a quasi-active guard to reduce background count rates and improve limits of detection. The results of this study indicate that this system shows tremendous potential for radiocarbon dating. Its great advantage is that it can give exceptional performance using standard low {sup 40}K borosilicate glass vials costing only a few cents each. For example, in an optimized counting window, 4.6-mL {sup 14}C benzene contained in a standard 7-mL glass vial produced a background count rate of 0.49 cpm and an efficiency of 70.3%, yielding a figure of merit (E{sup 2}V{sup 2}/B) value of 213,000 {+-}9,000 (where B = background count rate in counts per minute [cpm], E = percentage efficiency, and V = volume of benzene). This performance is comparable to published data for low-level instruments which employ active coincidence guard detectors and standard glass vials. When the same vials were recounted in vial holders, specially fabricated from BGO, the corresponding optimum values for background, efficiency and figure of merit, respectively, were 0.24 cpm, 61.0% and 328,000 {+-} 19,000. This performance is comparable to that of other low-level counting instruments when they are used in combination with specialized Teflon and silica vials. The BGO vial holders were also used in previous generations of Packard instruments which employ time resolved liquid scintillation counting (TR-LSC) for electronic background reduction and this resulted in significant improvements in performance.
NASA Astrophysics Data System (ADS)
Schou, Jesper; Beck, John G.
2001-01-01
Simple convection models estimate the depth of supergranulation at approximately 15,000 km which suggests that supergranules should rotate at the rate of the plasma in the outer 2% of the Sun by radius. Previous measurements (Snodgrass & Ulrich, 1990; Beck & Schou, 2000) found that supergranules rotate significantly faster than this, with a size-dependent rotation rate. We expand on previous work and show that the torsional oscillation signal seen in the supergranules tracks that obtained for normal modes. We also find that the amplitudes and lifetimes of the supergranulation are size dependent.
Turbulence at quasi-parallel and quasi-perpendicular bow shocks
NASA Astrophysics Data System (ADS)
Pitna, Alexander; Zastenker, Georgy; Nemecek, Zdenek; Safrankova, Jana
2016-07-01
A solar wind is a highly turbulent medium carrying various modes of magnetohydrodynamic and kinetic instabilities. During its supersonic expansion, it meets obstacles like planetary magnetospheres and bow shocks are formed. Depending on the orientation of the ambient magnetic field with respect to the local shock normal, either quasi-parallel or quasi-perpendicular shocks can be formed. Particles reflected at the ramp of the quasi-parallel shock are streaming far upstream along the magnetic field lines, giving rise to all sorts of instabilities like SLAMS and ULF waves. In the case of the quasi-perpendicular bow shock, the reflected particles influence only a narrow upstream region of the order of the proton gyroradius but the downstream plasma becomes highly turbulent regardless of the shock type. We analyze the high cadence (31 ms) data from the BMSW instrument onboard the Spektr-R spacecraft and compare the frequency spectra of observed turbulence in MHD and kinetic ranges in upstream and downstream regions of the supercritical quasi-parallel and quasi-perpendicular bow shocks. We found that the change in the fluctuation level (from upstream to downstream) as well as the spectral indices differ substantially in the MHD and kinetic ranges for both types of bow shock.
NASA Astrophysics Data System (ADS)
Dziembowski, W.
Sunspot observations made by Johannes Hevelius in 1642 - 1644 are the first ones providing significant information about the solar differential rotation. In modern astronomy the determination of the rotation rate is done in a routine way by measuring positions of various structures on the solar surface as well as by studying the Doppler shifts of spectral lines. In recent years a progress in helioseismology enabled determination of the rotation rate in the layers inaccessible for direct observations. There are still uncertainties concerning, especially, the temporal variations of the rotation rate and its behaviour in the radiative interior. We are far from understanding the observations. Theoretical works have not yet resulted in a satisfactory model for the angular momentum transport in the convective zone.
NASA Astrophysics Data System (ADS)
Fletcher, N. H.; Tarnopolsky, A. Z.; Lai, J. C. S.
2002-03-01
Free rotational aerophones such as the bullroarer, which consists of a wooden slat whirled around on the end of a string, and which emits a loud pulsating roar, have been used in many ancient and traditional societies for ceremonial purposes. This article presents an experimental and theoretical investigation of this instrument. The aerodynamics of rotational behavior is elucidated, and relates slat rotation frequency to slat width and velocity through the air. Analysis shows that sound production is due to generation of an oscillating-rotating dipole across the slat, the role of the vortices shed by the slat being relatively minor. Apparent discrepancies between the behavior of a bullroarer slat and a slat mounted on an axle in a wind tunnel are shown to be due to viscous friction in the bearings of the wind-tunnel experiment.
Probabilistic stellar rotation periods with Gaussian processes
NASA Astrophysics Data System (ADS)
Angus, Ruth; Aigrain, Suzanne; Foreman-Mackey, Daniel
2015-08-01
Stellar rotation has many applications in the field of exoplanets. High-precision photometry from space-based missions like Kepler and K2 allows us to measure stellar rotation periods directly from light curves. Stellar variability produced by rotation is usually not sinusoidal or perfectly periodic, therefore sine-fitting periodograms are not well suited to rotation period measurement. Autocorrelation functions are often used to extract periodic information from light curves, however uncertainties on rotation periods measured by autocorrelation are difficult to define. A ‘by eye’ check, or a set of heuristic criteria are used to validate measurements and rotation periods are only reported for stars that pass this vetting process. A probabilistic rotation period measurement method, with a suitable generative model bypasses the need for a validation stage and can produce realistic uncertainties. The physics driving the production of variability in stellar light curves is still poorly understood and difficult to model. We therefore use an effective model for stellar variability: a Gaussian process with a quasi-periodic covariance function. By injecting fake signals into Kepler light curves we show that the GP model is well suited to quasi-periodic, non-sinusoidal signals, is capable of modelling noise and physical signals simultaneously and provides probabilistic rotation period measurements with realistic uncertainties.
NASA Astrophysics Data System (ADS)
Pindsoo, Katri; Soomere, Tarmo
2016-04-01
high water levels are different, vary markedly along the coast and provide a useful quantification of the vulnerability of single coastal segments with respect to coastal flooding. The formal linear trends in the extreme values of these water level components exhibit radically different spatial variations. The slopes of the trends in the weekly average are almost constant (~4 cm/decade for 8-day running average) along the entire eastern Baltic Sea coast. This first of all indicates that the duration of storm sequences has increased. The trends for maxima of local storm surge heights represent almost the entire spatial variability in the water level extremes. Their slopes are almost zero at the open Baltic Proper coasts of the Western Estonian archipelago. Therefore, an increase in wind speed in strong storms is unlikely in this area. In contrast, the slopes in question reach 5-7 cm/decade in the eastern Gulf of Finland and Gulf of Riga. This feature suggests that wind direction in strongest storms may have rotated in the northern Baltic Sea.
Quasi-Random Sequence Generators.
Energy Science and Technology Software Center (ESTSC)
1994-03-01
Version 00 LPTAU generates quasi-random sequences. The sequences are uniformly distributed sets of L=2**30 points in the N-dimensional unit cube: I**N=[0,1]. The sequences are used as nodes for multidimensional integration, as searching points in global optimization, as trial points in multicriteria decision making, as quasi-random points for quasi Monte Carlo algorithms.
Vortices in a rotating Bose-Einstein condensate under extreme elongation
Sanchez-Lotero, P.; Palacios, J.J.
2005-10-15
We investigate a nonaxisymmetric rotating Bose-Einstein condensate (BEC) in the limit of rotation frequency for which the BEC transforms into a quasi-one-dimensional system. We compute the vortex lattice wave function by minimizing the Gross-Pitaevskii energy functional in the lowest Landau level approximation for different confinement potentials. The condensate typically presents a changing number of vortex rows as a function of the interaction strength or rotation-confinement ratio. More specifically, the vortex lattices can be classified into two classes according to their symmetry with respect to the longitudinal axis. These two classes correspond to different local minima of the energy functional and evolve independently as a function of the various parameters.
Rotational Orientation Effects in NO(X) + Ar Inelastic Collisions.
Brouard, M; Chadwick, H; Gordon, S D S; Hornung, B; Nichols, B; Aoiz, F J; Stolte, S
2015-12-17
Rotational angular momentum orientation effects in the rotationally inelastic collisions of NO(X) with Ar have been investigated both experimentally and theoretically at a collision energy of 530 cm(-1). The collision-induced orientation has been determined experimentally using a hexapole electric field to select the ϵ = -1 Λ-doublet level of the NO(X) j = 1/2 initial state. Fully quantum state resolved polarization-dependent differential cross sections were recorded experimentally using a crossed molecular beam apparatus coupled with a (1 + 1') resonance-enhanced multiphoton ionization detection scheme and subsequent velocity-map imaging. To determine the NO sense of rotation, the probe radiation was circularly polarized. Experimental orientation polarization-dependent differential cross sections are compared with those obtained from quantum mechanical scattering calculations and are found to be in good agreement. The origin of the collision-induced orientation has been investigated by means of close-coupled quantum mechanical, quantum mechanical hard shell, quasi-classical trajectory (QCT), and classical hard shell calculations at the same collision energy. Although there is evidence for the operation of limiting classical mechanisms, the rotational orientation cannot be accounted for by QCT calculations and is found to be strongly influenced by quantum mechanical effects. PMID:26413997
Lin, Hui; Sun, Wanchun; Zhang, Zulin; Chapman, Stephen J; Freitag, Thomas E; Fu, Jianrong; Zhang, Xin; Ma, Junwei
2016-04-01
This work investigated the responses of antibiotic resistance genes (ARGs) and the soil microbial community in a paddy-upland rotation system to mineral fertilizer (NPK) and different application dosages of manure combined with NPK. The occurrence of five tetracycline ARGs (tetA, tetB, tetC, tetG and tetW), two sulfonamide ARGs (sul1 and sul2) and one genetic element (IntI1) was quantified. NPK application showed only slight or no impact on soil ARGs abundances compared with the control without fertilizer. Soil ARGs abundances could be increased by manure-NPK application but was related to manure dosage (2250-9000 kg ha(-1)). Principal component analysis (PCA) showed that the soil ARG profile of the treatment with 9000 kg ha(-1) manure separated clearly from the other treatments; the ARGs that contributed most to the discrimination of this treatment were tetA, tetG, tetW, sul1, sul2 and IntI1. Community level physiological profile (CLPP) analysis showed that increasing manure dosage from 4500 kg ha(-1) to 9000 kg ha(-1) induced a sharp increase in almost all of the detected ARGs but would not change the microbial community at large. However, 9000 kg ha(-1) manure application produced a decline in soil microbial activity. Determination of antibiotics and heavy metals in soils suggested that the observed bloom of soil ARGs might associate closely with the accumulation of copper and zinc in soil. PMID:26774780
Finite rotation and nonlinear beam kinematics
NASA Technical Reports Server (NTRS)
Hodges, Dewey H.
1987-01-01
Standard means of representing finite rotation in rigid-body kinematics, including orientation angles, Euler parameters, and Rodrigues parameters, are reviewed and compared. General kinematical relations for a beam theory that treats arbitrarily large rotation are then presented. The standard methods of representing finite rotations are applied to these kinematical expressions, and comparison is made among the standard methods and additional methods found in the literature, such as quasi-coordinates and linear combinations of projection angles. The method of Rodrigues parameters is shown to stand out for both its simplicity and generality when applied to beam kinematics, a result that is really missing from the literature.
Sims, J.R.; Naumovich, G.J.; Hoang, T.A.; Dent, P.C.
1996-05-01
The National High Magnetic Field Laboratory is completing a quasi-continuous magnet which will sustain a constant field of 60 T for 100 ms in a 32-mm 77 K bore. This magnet consists of 9 mechanically independent, nested, liquid nitrogen-cooled coils which are individually reinforced by high-strength stainless steel outer shells. The coils were wound from rectangular large cross-section, high-strength, high-conductivity copper conductor insulated wtih polyimide and fiberglass tapes. After winding, the coils were inserted into closely fitted, stainless steel reinforcing shells and impregnated with epoxy resin. Design, analysis, material, fabrication and operational issues for this class of magnets are reviewed. Fabrication and quality assurance testing of the 60 T coil set are covered in detail. Future growth of and possible links from this technology to other magnet systems are discussed. Needed improvements in design, analysis, materials, and fabrication are outlined.
Energy Spectra of Strongly Stratified and Rotating Turbulence
NASA Technical Reports Server (NTRS)
Mahalov, Alex; Nicolaenko, Basil; Zhou, Ye
1998-01-01
Turbulence under strong stratification and rotation is usually characterized as quasi-two dimensional turbulence. We develop a "quasi-two dimensional" energy spectrum which changes smoothly between the Kolmogorov -5/3 law (no stratification), the -2 scalings of Zhou for the case of strong rotation, as well as the -2 scalings for the case of strong rotation and stratification. For strongly stratified turbulence, the model may give the -2 scaling predicted by Herring; and the -5/3 scaling indicated by some mesoscale observations.
NASA Technical Reports Server (NTRS)
Dickey, Jean O.
1995-01-01
The study of the Earth's rotation in space (encompassing Universal Time (UT1), length of day, polar motion, and the phenomena of precession and nutation) addresses the complex nature of Earth orientation changes, the mechanisms of excitation of these changes and their geophysical implications in a broad variety of areas. In the absence of internal sources of energy or interactions with astronomical objects, the Earth would move as a rigid body with its various parts (the crust, mantle, inner and outer cores, atmosphere and oceans) rotating together at a constant fixed rate. In reality, the world is considerably more complicated, as is schematically illustrated. The rotation rate of the Earth's crust is not constant, but exhibits complicated fluctuations in speed amounting to several parts in 10(exp 8) [corresponding to a variation of several milliseconds (ms) in the Length Of the Day (LOD) and about one part in 10(exp 6) in the orientation of the rotation axis relative to the solid Earth's axis of figure (polar motion). These changes occur over a broad spectrum of time scales, ranging from hours to centuries and longer, reflecting the fact that they are produced by a wide variety of geophysical and astronomical processes. Geodetic observations of Earth rotation changes thus provide insights into the geophysical processes illustrated, which are often difficult to obtain by other means. In addition, these measurements are required for engineering purposes. Theoretical studies of Earth rotation variations are based on the application of Euler's dynamical equations to the problem of finding the response of slightly deformable solid Earth to variety of surface and internal stresses.
Quasi-active suspension design using magnetorheological dampers
NASA Astrophysics Data System (ADS)
Potter, Jack N.; Neild, Simon A.; Wagg, David J.
2011-05-01
Quasi-active damping is a method of coupled mechanical and control system design using multiple semi-active dampers. By designing the systems such that the desired control force may always be achieved using a combination of the dampers, quasi-active damping seeks to approach levels of vibration isolation achievable through active damping, whilst retaining the desirable attributes of semi-active systems. In this article a design is proposed for a quasi-active, base-isolating suspension system. Control laws are firstly defined in a generalised form, where semi-active dampers are considered as idealised variable viscous dampers. This system is used to demonstrate in detail the principles of quasi-active damping, in particular the necessary interaction between mechanical and control systems. It is shown how such a system can produce a tunable, quasi-active region in the frequency response of very low displacement transmissibility. Quasi-active control laws are then proposed which are specific for use with magnetorheological dampers. These are validated in simulation using a realistic model of the damper dynamics, again producing a quasi-active region in the frequency response. Finally, the robustness of the magnetorheological, quasi-active suspension system is demonstrated.
NASA Technical Reports Server (NTRS)
1979-01-01
In aircraft turbine engine research, certain investigations require extremely precise measurement of the position of a rotating part, such as the rotor, a disc-like part of the engine's compressor which revolves around a shaft at extremely high speeds. For example, in studies of airflow velocity within a compressor, researchers need to know-for data correlation the instantaneous position of a given spot on the rotor each time a velocity measurement is made. Earlier methods of measuring rotor shaft angle required a physical connection to the shaft, which limited the velocity of the rotating object.
Govor, L. I. Demidov, A. M.; Kurkin, V. A.; Mikhailov, I. V.
2015-03-15
Various reasons for the absence of rotational levels for J{sup π}K = 0{sup +}0{sub 2} and 2{sup +}2{sub 2} nonrotational states in {sup 164}Dy and {sup 166}Er are considered. Preference is given to the effect of the excitation of an anharmonic two-phonon state in pair vibrations of the superconducting type.
Lafferty, Walter; Flaud, Jean-marie; Sams, Robert L.; Ngom, El Hadji A.
2008-11-01
A high resolution (0.0018 cm-1) Fourier transform instrument has been used to record the spectrum of an enriched 34S (95.3 %) sample of sulfur dioxide. A thorough analysis of the ν2, 2ν2 - ν2 , ν1, ν1 + ν2 - ν2, ν3, ν2 + ν3 - ν2, ν1 + ν2 and ν2 + ν3 bands has been carried out leading to a large set of assigned lines. From these lines ground state combination differences were obtained and fitted together with the existing microwave, millimeter, and terahertz rotational lines. An improved set of ground state rotational constants were obtained. Next, the upper state rotational levels were fitted. For the (010), (110), (011) states, a simple Watson type Hamilton sufficed. However, it was necessary to include explicitly interacting terms in the Hamiltonian matrix in order to fit the rotational levels of the (020), (100) and (101) states to within their experimental accuracy. More explicitly, it was necessary to use a ΔK=2 term to model the Fermi interaction between the (020) and (100) levels and a ΔK=3 term to model the Coriolis interaction between the (100) and (001) levels. Precise Hamiltonian constants were derived for the (000), (010), (100), (001), (020), (110) and (011) vibrational states.
NASA Astrophysics Data System (ADS)
Walker, A. R. Hight; Suenram, R. D.; Samuels, Alan; Jensen, James; Ellzy, Michael W.; Lochner, J. Michael; Zeroka, Daniel
2001-05-01
As part of an effort to examine the possibility of using molecular-beam Fourier-transform microwave spectroscopy to unambiguously detect and monitor chemical warfare agents, we report the first observation and assignment of the rotational spectrum of the nerve agent Sarin (GB) (Methylphosphonofluoridic acid 1-methyl-ethyl ester, CAS #107-44-8) at frequencies between 10 and 22 GHz. Only one of the two low-energy conformers of this organophosphorus compound (C4H10FO2P) was observed in the rotationally cold (Trot<2 K) molecular beam. The experimental asymmetric-rotor ground-state rotational constants of this conformer are A=2874.0710(9) MHz, B=1168.5776(4) MHz, C=1056.3363(4) MHz (Type A standard uncertainties are given, i.e., 1σ), as obtained from a least-squares analysis of 74 a-, b-, and c-type rotational transitions. Several of the transitions are split into doublets due to the internal rotation of the methyl group attached to the phosphorus. The three-fold-symmetry barrier to internal rotation estimated from these splittings is 677.0(4) cm-1. Ab initio electronic structure calculations using Hartree-Fock, density functional, and Moller-Plesset perturbation theories have also been made. The structure of the lowest-energy conformer determined from a structural optimization at the MP2/6-311G** level of theory is consistent with our experimental findings.
NASA Astrophysics Data System (ADS)
Wang, Feng; Fu, G. Y.; Breslau, J. A.; Tritz, Kevin; Liu, J. Y.
2013-07-01
Plasmas in spherical and conventional tokamaks, with weakly reversed shear q profile and minimum q above but close to unity, are susceptible to an non-resonant (m,n) = (1,1) internal kink mode. This mode can saturate and persist and can induce a (2,1) seed island for Neoclassical Tearing Mode. [Breslau et al. Nucl. Fusion 51, 063027 (2011)]. The mode can also lead to large energetic particle transport and significant broadening of beam-driven current. Motivated by these important effects, we have carried out extensive nonlinear simulations of the mode with finite toroidal rotation using parameters and profiles of an NTSX plasma with a weakly reversed shear profile. The numerical results show that, at the experimental level, plasma rotation has little effect on either equilibrium or linear stability. However, rotation can significantly influence the nonlinear dynamics of the (1,1) mode and the induced (2,1) magnetic island. The simulation results show that a rotating helical equilibrium is formed and maintained in the nonlinear phase at finite plasma rotation. In contrast, for non-rotating cases, the nonlinear evolution exhibits dynamic oscillations between a quasi-2D state and a helical state. Furthermore, the effects of rotation are found to greatly suppress the (2,1) magnetic island even at a low level.
Wang, Feng; Liu, J. Y.; Fu, G. Y.; Breslau, J. A.; Tritz, Kevin
2013-07-15
Plasmas in spherical and conventional tokamaks, with weakly reversed shear q profile and minimum q above but close to unity, are susceptible to an non-resonant (m,n) = (1,1) internal kink mode. This mode can saturate and persist and can induce a (2,1) seed island for Neoclassical Tearing Mode. [Breslau et al. Nucl. Fusion 51, 063027 (2011)]. The mode can also lead to large energetic particle transport and significant broadening of beam-driven current. Motivated by these important effects, we have carried out extensive nonlinear simulations of the mode with finite toroidal rotation using parameters and profiles of an NTSX plasma with a weakly reversed shear profile. The numerical results show that, at the experimental level, plasma rotation has little effect on either equilibrium or linear stability. However, rotation can significantly influence the nonlinear dynamics of the (1,1) mode and the induced (2,1) magnetic island. The simulation results show that a rotating helical equilibrium is formed and maintained in the nonlinear phase at finite plasma rotation. In contrast, for non-rotating cases, the nonlinear evolution exhibits dynamic oscillations between a quasi-2D state and a helical state. Furthermore, the effects of rotation are found to greatly suppress the (2,1) magnetic island even at a low level.
New Classes of Quasi-helically Symmetric Stellarators
L.P. Ku and A.H. Boozer
2010-08-09
New classes of quasi-helically symmetric stellarators with aspect ratios ≤ 10 have been found which are stable to the perturbation of magnetohydrodynamic modes at plasma pressures of practical interest. These configurations have large rotational transform and good quality of flux surfaces. Characteristics of some selected examples are discussed in detail. The feasibility of using modular coils for these stellarators has been investigated. It is shown that practical designs for modular coils can be achieved.
Flow Structure on a Flapping Wing: Quasi-Steady Limit
NASA Astrophysics Data System (ADS)
Ozen, Cem; Rockwell, Donald
2011-11-01
The flapping motion of an insect wing typically involves quasi-steady motion between extremes of unsteady motion. This investigation characterizes the flow structure for the quasi-steady limit via a rotating wing in the form of a thin rectangular plate having a low aspect ratio (AR =1). Particle Image Velocimetry (PIV) is employed, in order to gain insight into the effects of centripetal and Coriolis forces. Vorticity, velocity and streamline patterns are used to describe the overall flow structure with an emphasis on the leading-edge vortex. A stable leading-edge vortex is maintained over effective angles of attack from 30° to 75° and it is observed that at each angle of attack the flow structure remains relatively same over the Reynolds number range from 3,600 to 14,500. The dimensionless circulation of the leading edge vortex is found to be proportional to the effective angle of attack. Quasi-three-dimensional construction of the flow structure is used to identify the different regimes along the span of the wing which is then complemented by patterns on cross flow planes to demonstrate the influence of root and tip swirls on the spanwise flow. The rotating wing results are also compared with the equivalent of translating wing to further illustrate the effects of the rotation.
NASA Astrophysics Data System (ADS)
Salem, Salem; Halford, Carl; Moyer, Steve; Gundy, Matthew
2009-08-01
A new approach to linear discriminant analysis (LDA), called orthogonal rotational LDA (ORLDA) is presented. Using ORLDA and properly accounting for target size allowed development of a new clutter metric that is based on the Laplacian pyramid (LP) decomposition of clutter images. The new metric achieves correlation exceeding 98% with expert human labeling of clutter levels in a set of 244 infrared images. Our clutter metric is based on the set of weights for the LP levels that best classify images into clutter levels as manually classified by an expert human observer. LDA is applied as a preprocessing step to classification. LDA suffers from a few limitations in this application. Therefore, we propose a new approach to LDA, called ORLDA, using orthonormal geometric rotations. Each rotation brings the LP feature space closer to the LDA solution while retaining orthogonality in the feature space. To understand the effects of target size on clutter, we applied ORLDA at different target sizes. The outputs are easily related because they are functions of orthogonal rotation angles. Finally, we used Bayesian decision theory to learn class boundaries for clutter levels at different target sizes.
Quasi-periodic oscillations of perturbed tori
NASA Astrophysics Data System (ADS)
Parthasarathy, Varadarajan; Manousakis, Antonios; Kluźniak, Włodzimierz
2016-05-01
We performed axisymmetric hydrodynamical simulations of oscillating tori orbiting a non-rotating black hole. The tori in equilibrium were constructed with a constant distribution of angular momentum in a pseudo-Newtonian potential (Kluźniak-Lee). Motions of the torus were triggered by adding subsonic velocity fields: radial, vertical and diagonal to the tori in equilibrium. As the perturbed tori evolved in time, we measured L2 norm of density and obtained the power spectrum of L2 norm which manifested eigenfrequencies of tori modes. The most prominent modes of oscillation excited in the torus by a quasi-random perturbation are the breathing mode and the radial and vertical epicyclic modes. The radial and the plus modes, as well as the vertical and the breathing modes will have frequencies in an approximate 3:2 ratio if the torus is several Schwarzschild radii away from the innermost stable circular orbit. Results of our simulations may be of interest in the context of high-frequency quasi-periodic oscillations observed in stellar-mass black hole binaries, as well as in supermassive black holes.
Quasi-periodicity in relative quasi-periodic tori
NASA Astrophysics Data System (ADS)
Fassò, Francesco; García-Naranjo, Luis C.; Giacobbe, Andrea
2015-10-01
At variance from the cases of relative equilibria and relative periodic orbits of dynamical systems with symmetry, the dynamics in relative quasi-periodic tori (namely, subsets of the phase space that project to an invariant torus of the reduced system on which the flow is quasi-periodic) is not yet completely understood. Even in the simplest situation of a free action of a compact and abelian connected group, the dynamics in a relative quasi-periodic torus is not necessarily quasi-periodic. It is known that quasi-periodicity of the unreduced dynamics is related to the reducibility of the reconstruction equation, and sufficient conditions for it are virtually known only in a perturbation context. We provide a different, though equivalent, approach to this subject, based on the hypothesis of the existence of commuting, group-invariant lifts of a set of generators of the reduced torus. Under this hypothesis, which is shown to be equivalent to the reducibility of the reconstruction equation, we give a complete description of the structure of the relative quasi-periodic torus, which is a principal torus bundle whose fibers are tori of a dimension which exceeds that of the reduced torus by at most the rank of the group. The construction can always be done in such a way that these tori have minimal dimension and carry ergodic flow.
NASA Technical Reports Server (NTRS)
Del Genio, Anthony D.; Suozzo, Robert J.
1987-01-01
As a preliminary step in the development of a general circulation model for general planetary use, a simplified vesion of thef GISS Model I GCM has been run at various rotation periods to investigate differences between the dynamical regimes of rapidly and slowly rotating planets. To isolate the dynamical processes, the hydrologic cycle is suppressed and the atmosphere is forced with perpetual annual mean solar heating. All other parameters except the rotation period remain fixed at their terrestrial values. Experiments were conducted for rotation periods of 2/3, 1, 2, 4, 8, 16, 64 and 256 days. The results are in qualitative agreement with similar experiments carried out previously with other GCMs and with certain aspects of one Venus GCM simulation. As rotation rate decreases, the energetics shifts from baroclinc to quasi-barotropic when the Rossby radius of deformation reaches planetary scale. The Hadley cell expands poleward and replaces eddies as the primary mode of large-scale heat transport. Associated with this is a poleward shift of the baroclinic zone and jet stream and a reduction of the equator-pole temperature contrast. Midlatitude jet strength peaks at 8 days period, as does the weak positive equatorial zonal wind which occurs at upper levels at all rotation periods. Eddy momentum transport switches from poleward to equatorward at the same period. Tropospheric mean static stability generally increases in the tropics and decreases in midlatitudes as rotation rate decreases, but the global mean static stability is independent of rotation rate. The peak in the eddy kinetic energy spectrum shifts toward lower wavenumbers, reaching wavenumber 1 at a period of 8 days. Implications of these results for the dynamics of Venus and Titan are discussed. Specifically, it is suggested that the extent of low-level convection determines whether the Gierasch mechanism contributes significantly to equatorial superrotation on these planets.
Sun, Junwei; Shen, Yi
2015-07-01
The definition for ideal memory system is so strict that some physical elements cannot exist in the real world. In this paper, an ideal memory system can be extended to generate 15 different kinds of quasi-ideal memory systems, which are included in memory systems as its special cases and are different from ideal memory system. For a system to be a quasi-ideal memory system, it should show three unique fingerprints: 1) the pinched hysteretic loop of a quasi-ideal memory system must be odd symmetrical in the plane; 2) the pinched hysteretic loop of a quasi-ideal memory system must be "self-crossing"; and 3) the slope of tangent line for the pinched hysteresis loop must be strictly monotone in a given period. PMID:25204007
Rotational evolution of slow-rotator sequence stars
NASA Astrophysics Data System (ADS)
Lanzafame, A. C.; Spada, F.
2015-12-01
Context. The observed relationship between mass, age and rotation in open clusters shows the progressive development of a slow-rotator sequence among stars possessing a radiative interior and a convective envelope during their pre-main sequence and main-sequence evolution. After 0.6 Gyr, most cluster members of this type have settled on this sequence. Aims: The observed clustering on this sequence suggests that it corresponds to some equilibrium or asymptotic condition that still lacks a complete theoretical interpretation, and which is crucial to our understanding of the stellar angular momentum evolution. Methods: We couple a rotational evolution model, which takes internal differential rotation into account, with classical and new proposals for the wind braking law, and fit models to the data using a Monte Carlo Markov chain (MCMC) method tailored to the problem at hand. We explore to what extent these models are able to reproduce the mass and time dependence of the stellar rotational evolution on the slow-rotator sequence. Results: The description of the evolution of the slow-rotator sequence requires taking the transfer of angular momentum from the radiative core to the convective envelope into account. We find that, in the mass range 0.85-1.10 M⊙, the core-envelope coupling timescale for stars in the slow-rotator sequence scales as M-7.28. Quasi-solid body rotation is achieved only after 1-2 Gyr, depending on stellar mass, which implies that observing small deviations from the Skumanich law (P ∝ √{t}) would require period data of older open clusters than is available to date. The observed evolution in the 0.1-2.5 Gyr age range and in the 0.85-1.10 M⊙ mass range is best reproduced by assuming an empirical mass dependence of the wind angular momentum loss proportional to the convective turnover timescale and to the stellar moment of inertia. Period isochrones based on our MCMC fit provide a tool for inferring stellar ages of solar-like main
Quasi-bound state lifetimes and classical periodic orbits in HOCl
NASA Astrophysics Data System (ADS)
Barr, Alex; Na, Kyungsun; Reichl, Linda
2011-03-01
We use a discrete variable representation together with reaction matrix theory to calculate the quasi-bound states of a Chlorine atom scattering off a diatomic molecule of Hydrogen and Oxygen. The lifetimes of these quasi-bound states are found to vary over six orders of magnitude in a very small energy window. By examining Husimi distributions for various quasi-bound states we show that the longest-lived quasi- bound states are anchored by an island of stability surrounding a stable periodic orbit in the otherwise chaotic classical phase space. This stable periodic orbit, which corresponds to Chlorine rotating around the HO molecule, is responsible for the very long lifetimes of these quasi-bound states.
Numerical investigation of the Earth's rotation during a complete precession cycle
NASA Technical Reports Server (NTRS)
Richardson, David L.
1992-01-01
A theory for the long-term rotational motion of the quasi-rigid Earth was constructed by numerical integration. The theory spans 72,000 years centered about 1968 A.D., and provides accurate rotational and positional data for the Earth in the recent past and the near future. The physical model is termed dynamically consistent because developments for the active forces and torques are truncated based solely on their magnitudes regardless of their origin. The model includes all appropriate forces and torques due to the geopotential and tidal effects as well as lunisolar and planetary contributions. The elastic and inelastic deformations due to tidal action were too small to affect the mass properties of the Earth at the truncation level of the model. However, long-term dissipative effects of the tidal forces and torques were not negligible. These considerations gave the model its quasi-rigid characterization. The numerical output provided both rotational and orbital-element data. The data were fitted throughout the 72,000-year range using Chebyshev polynomial series.
NH3 quantum rotators in Hofmann clathrates: intensity and width of rotational transition lines
NASA Astrophysics Data System (ADS)
Vorderwisch, Peter; Sobolev, Oleg; Desmedt, Arnaud
2004-07-01
Inelastic structure factors for rotational transitions of uniaxial NH3 quantum rotators, measured in a Hofmann clathrate with biphenyl as guest molecule, agree with those calculated for free rotators. A finite intrinsic line width, found for rotational transitions involving the rotational level j=3 at low temperature, supports a recently suggested model based on resonant rotor-rotor coupling. Present address: LPCM, CNRS-Université de Bordeaux I, 351 Cours de Libération, Talence F-33405, France.
Experimental Avalanches in a Rotating Drum
NASA Astrophysics Data System (ADS)
Hubard, Aline; O'Hern, Corey; Shattuck, Mark
We address the question of universality in granular avalanches and the system size effects on it. We set up an experiment made from a quasi-two-dimensional rotating drum half-filled with a monolayer of stainless-steel spheres. We measure the size of the avalanches created by the increased gravitational stress on the pile as we quasi-statically rotate the drum. We find two kinds of avalanches determined by the drum size. The size and duration distributions of the avalanches that do not span the whole system follow a power law and the avalanche shapes are self-similar and nearly parabolic. The distributions of the avalanches that span the whole system are limited by the maximal amount of potential energy stored in the system at the moment of the avalanche. NSF CMMI-1462439, CMMI-1463455.
Visualizing Compound Rotations with Virtual Reality
ERIC Educational Resources Information Center
Flanders, Megan; Kavanagh, Richard C.
2013-01-01
Mental rotations are among the most difficult of all spatial tasks to perform, and even those with high levels of spatial ability can struggle to visualize the result of compound rotations. This pilot study investigates the use of the virtual reality-based Rotation Tool, created using the Virtual Reality Modeling Language (VRML) together with…
Vortex structures of rotating Bose-Einstein condensates in an anisotropic harmonic potential
Matveenko, S. I.
2010-09-15
We found an analytical solution for the vortex structure in a rapidly rotating trapped Bose-Einstein condensate in the lowest Landau level approximation. This solution is exact in the limit of a large number of vortices and is obtained for the case of a condensate in a anisotropic harmonic potential. The solution describes as limiting cases both a triangle vortex lattice in the symmetric potential trap and a quasi-one-dimensional structure of vortex rows in an asymmetric case, when the rotation frequency is very close to the lower trapping potential frequency. The shape of the density profile is found to be close to the Thomas-Fermi inverted paraboloid form, except in the vicinity of edges of a condensate cloud.
Quasi-Static Hydrodynamic Limits
NASA Astrophysics Data System (ADS)
De Masi, Anna; Olla, Stefano
2015-12-01
We consider hydrodynamic limits of interacting particles systems with open boundaries, where the exterior parameters change in a time scale slower than the typical relaxation time scale. The limit deterministic profiles evolve quasi-statically. These limits define rigorously the thermodynamic quasi static transformations also for transitions between non-equilibrium stationary states. We study first the case of the symmetric simple exclusion, where duality can be used, and then we use relative entropy methods to extend to other models like zero range systems. Finally we consider a chain of anharmonic oscillators in contact with a thermal Langevin bath with a temperature gradient and a slowly varying tension applied to one end.
Quasi-biennial oscillation above 10 mb
Baldwin, M.P. Dunkerton, T.J. )
1991-07-01
It is shown that the quasi-biennial oscillation of the equatorial lower stratosphere was correlated with mean zonal wind in the upper stratosphere, 1979-90. Correlations were positive near 60{degree}N and 30{degree}S during northern hemisphere (NH) winter and negative in the equatorial upper stratosphere during all seasons. Spatial autocorrelation of mean zonal wind during NH winter was actually largest in the upper stratosphere, between 10{degree}S and 62{degree}N, due to strong coupling between tropical and extratropical flow at upper levels.
Quasi-periodic continuation along a continuous symmetry
NASA Astrophysics Data System (ADS)
Salomone, Matthew David
Given a system of differential equations which admits a continuous group of symmetries and possesses a periodic solution, we show that under certain nondegeneracy assumptions there always exists a continuous family containing infinitely many periodic and quasi-periodic trajectories. This generalizes the continuation method of Poincaré to orbits which are not necessarily periodic. We apply these results in the setting of the Lagrangian N -body problem of homogeneous potential to characterize an infinite family of rotating nonplanar "hip-hop" orbits in the four-body problem of equal masses, and show how some other trajectories in the N -body theory may be extended to infinite families of periodic and quasi-periodic trajectories.
Energy Transfer in Rotating Turbulence
NASA Technical Reports Server (NTRS)
Cambon, Claude; Mansour, Nagi N.; Godeferd, Fabien S.; Rai, Man Mohan (Technical Monitor)
1995-01-01
The influence or rotation on the spectral energy transfer of homogeneous turbulence is investigated in this paper. Given the fact that linear dynamics, e.g. the inertial waves regime tackled in an RDT (Rapid Distortion Theory) fashion, cannot Affect st homogeneous isotropic turbulent flow, the study of nonlinear dynamics is of prime importance in the case of rotating flows. Previous theoretical (including both weakly nonlinear and EDQNM theories), experimental and DNS (Direct Numerical Simulation) results are gathered here and compared in order to give a self-consistent picture of the nonlinear effects of rotation on tile turbulence. The inhibition of the energy cascade, which is linked to a reduction of the dissipation rate, is shown to be related to a damping due to rotation of the energy transfer. A model for this effect is quantified by a model equation for the derivative-skewness factor, which only involves a micro-Rossby number Ro(sup omega) = omega'/(2(OMEGA))-ratio of rms vorticity and background vorticity as the relevant rotation parameter, in accordance with DNS and EDQNM results fit addition, anisotropy is shown also to develop through nonlinear interactions modified by rotation, in an intermediate range of Rossby numbers (Ro(omega) = (omega)' and Ro(omega)w greater than 1), which is characterized by a marco-Rossby number Ro(sup L) less than 1 and Ro(omega) greater than 1 which is characterized by a macro-Rossby number based on an integral lengthscale L and the micro-Rossby number previously defined. This anisotropy is mainly an angular drain of spectral energy which tends to concentrate energy in tile wave-plane normal to the rotation axis, which is exactly both the slow and the two-dimensional manifold. In Addition, a polarization of the energy distribution in this slow 2D manifold enhances horizontal (normal to the rotation axis) velocity components, and underlies the anisotropic structure of the integral lengthscales. Finally is demonstrated the
Calkins, Michael A.; Julien, Keith; Marti, Philippe
2015-01-01
The linear theory for rotating compressible convection in a plane layer geometry is presented for the astrophysically relevant case of low Prandtl number gases. When the rotation rate of the system is large, the flow remains geostrophically balanced for all stratification levels investigated and the classical (i.e. incompressible) asymptotic scaling laws for the critical parameters are recovered. For sufficiently small Prandtl numbers, increasing stratification tends to further destabilize the fluid layer, decrease the critical wavenumber and increase the oscillation frequency of the convective instability. In combination, these effects increase the relative magnitude of the time derivative of the density perturbation contained in the conservation of mass equation to non-negligible levels; the resulting convective instabilities occur in the form of compressional quasi-geostrophic oscillations. We find that the anelastic equations, which neglect this term, cannot capture these instabilities and possess spuriously growing eigenmodes in the rapidly rotating, low Prandtl number regime. It is shown that the Mach number for rapidly rotating compressible convection is intrinsically small for all background states, regardless of the departure from adiabaticity. PMID:25792951
Morokoff, W.J.; Caflisch, R.E.
1995-12-01
The standard Monte Carlo approach to evaluating multidimensional integrals using (pseudo)-random integration nodes is frequently used when quadrature methods are too difficult or expensive to implement. As an alternative to the random methods, it has been suggested that lower error and improved convergence may be obtained by replacing the pseudo-random sequences with more uniformly distributed sequences known as quasi-random. In this paper quasi-random (Halton, Sobol`, and Faure) and pseudo-random sequences are compared in computational experiments designed to determine the effects on convergence of certain properties of the integrand, including variance, variation, smoothness, and dimension. The results show that variation, which plays an important role in the theoretical upper bound given by the Koksma-Hlawka inequality, does not affect convergence, while variance, the determining factor in random Monte Carlo, is shown to provide a rough upper bound, but does not accurately predict performance. In general, quasi-Monte Carlo methods are superior to random Monte Carlo, but the advantage may be slight, particularly in high dimensions or for integrands that are not smooth. For discontinuous integrands, we derive a bound which shows that the exponent for algebraic decay of the integration error from quasi-Monte Carlo is only slightly larger than {1/2} in high dimensions. 21 refs., 6 figs., 5 tabs.
NASA Astrophysics Data System (ADS)
Morokoff, William J.; Caflisch, Russel E.
1995-12-01
The standard Monte Carlo approach to evaluating multidimensional integrals using (pseudo)-random integration nodes is frequently used when quadrature methods are too difficult or expensive to implement. As an alternative to the random methods, it has been suggested that lower error and improved convergence may be obtained by replacing the pseudo-random sequences with more uniformly distributed sequences known as quasi-random. In this paper quasi-random (Halton, Sobol', and Faure) and pseudo-random sequences are compared in computational experiments designed to determine the effects on convergence of certain properties of the integrand, including variance, variation, smoothness, and dimension. The results show that variation, which plays an important role in the theoretical upper bound given by the Koksma-Hlawka inequality, does not affect convergence, while variance, the determining factor in random Monte Carlo, is shown to provide a rough upper bound, but does not accurately predict performance. In general, quasi-Monte Carlo methods are superior to random Monte Carlo, but the advantage may be slight, particularly in high dimensions or for integrands that are not smooth. For discontinuous integrands, we derive a bound which shows that the exponent for algebraic decay of the integration error from quasi-Monte Carlo is only slightly larger than {1}/{2} in high dimensions.
Marginal Stability Diagrams for Infinite-n Ballooning Modes in Quasi-symmetric Stellarators
S.R. Hudson; C.C. Hegna; R. Torasso; A. Ware
2003-12-05
By perturbing the pressure and rotational-transform profiles at a selected surface in a given equilibrium, and by inducing a coordinate variation such that the perturbed state is in equilibrium, a family of magnetohydrodynamic equilibria local to the surface and parameterized by the pressure gradient and shear is constructed for arbitrary stellarator geometry. The geometry of the surface is not changed. The perturbed equilibria are analyzed for infinite-n ballooning stability and marginal stability diagrams are constructed that are analogous to the (s; alpha) diagrams constructed for axi-symmetric configurations. The method describes how pressure and rotational-transform gradients influence the local shear, which in turn influences the ballooning stability. Stability diagrams for the quasi-axially-symmetric NCSX (National Compact Stellarator Experiment), a quasi-poloidally-symmetric configuration and the quasi-helically-symmetric HSX (Helically Symmetric Experiment) are presented. Regions of second-stability are observed in both NCSX and the quasi-poloidal configuration, whereas no second stable region is observed for the quasi-helically symmetric device. To explain the different regions of stability, the curvature and local shear of the quasi-poloidal configuration are analyzed. The results are seemingly consistent with the simple explanation: ballooning instability results when the local shear is small in regions of bad curvature. Examples will be given that show that the structure, and stability, of the ballooning mode is determined by the structure of the potential function arising in the Schroedinger form of the ballooning equation.
NASA Astrophysics Data System (ADS)
Tennyson, Jonathan; Bernath, Peter F.; Brown, Linda R.; Campargue, Alain; Császár, Attila G.; Daumont, Ludovic; Gamache, Robert R.; Hodges, Joseph T.; Naumenko, Olga V.; Polyansky, Oleg L.; Rothman, Laurence S.; Vandaele, Ann Carine; Zobov, Nikolai F.; Dénes, Nóra; Fazliev, Alexander Z.; Furtenbacher, Tibor; Gordon, Iouli E.; Hu, Shui-Ming; Szidarovszky, Tamás; Vasilenko, Irina A.
2014-07-01
This paper is the fourth of a series of papers reporting critically evaluated rotational-vibrational line positions, transition intensities, pressure dependences, and energy levels, with associated critically reviewed assignments and uncertainties, for all the main isotopologues of water. This paper presents energy level and transition data for the following doubly and triply substituted isotopologues of water: D216O, D217O, and D218O. The MARVEL (Measured Active Rotational-Vibrational Energy Levels) procedure is used to determine the levels, the lines, and their self-consistent uncertainties for the spectral regions 0-14 016, 0-7969, and 0-9108 cm-1 for D216O, D217O, and D218O, respectively. For D216O, D217O, and D218O, 53 534, 600, and 12 167 lines are considered, respectively, from spectra recorded in absorption at room temperature and in emission at elevated temperatures. The number of validated energy levels is 12 269, 338, and 3351 for D216O, D217O, and D218O, respectively. The energy levels have been checked against the ones determined, with an average accuracy of about 0.03 cm-1, from variational rovibrational computations employing exact kinetic energy operators and an accurate potential energy surface. Furthermore, the rovibrational labels of the energy levels have been validated by an analysis of the computed wavefunctions using the rigid-rotor decomposition (RRD) scheme. The extensive list of MARVEL lines and levels obtained is deposited in the Supplementary Material of this paper, in a distributed information system applied to water, W@DIS, and on the official MARVEL website, where they can easily be retrieved.
New Classes of Quasi-Axisymmetric Stellarator Configurations
Ku LP, Garabedian PR
2005-10-03
We have identified and developed new classes of quasi-axially symmetric configurations which have attractive properties from the standpoint of both near-term physics experiments and long-term power producing reactors. These new configurations were developed as a result of surveying the aspect ratio-rotational transform space to identify regions endowed with particularly interesting features. These include configurations with very small aspect ratios ({approx}2.5) having superior quasi-symmetry and energetic particle confinement characteristics, and configurations with strongly negative global magnetic shear from externally supplied rotational transforms so that the overall rotational transform, when combined with the transform from bootstrap currents at finite plasma pressures, will yield a small but positive shear, making the avoidance of low order rational surfaces at a given operating beta possible. Additionally, we have found configurations with NCSX-like characteristics but with the biased components in the magnetic spectrum that allow us to improve the confinement of energetic particles. For each new class of configurations, we have designed coils as well to ensure that the new configurations are realizable and engineering-wise feasible. The coil designs typically have coil aspect ratios R/{Delta}{sub min}(C-P) {le} 6 and coil separation ratios R/{Delta}{sub min}(C-C) {le} 10, where R is the plasma major radius, {Delta}{sub min}(C-P) and {Delta}{sub min}(C-C) are the minimum coil to plasma and coil to coil separations, respectively. These coil properties allow power producing reactors be designed with major radii less than 9 meters for DT plasmas with a full breeding blanket. The good quasi-axisymmetry limits the energy loss of {alpha} particles to below 10%.
NASA Technical Reports Server (NTRS)
Bradley, William; Bird, Ross; Eldred, Dennis; Zook, Jon; Knowles, Gareth
2013-01-01
This work involved developing spacequalifiable switch mode DC/DC power supplies that improve performance with fewer components, and result in elimination of digital components and reduction in magnetics. This design is for missions where systems may be operating under extreme conditions, especially at elevated temperature levels from 200 to 300 degC. Prior art for radiation-tolerant DC/DC converters has been accomplished utilizing classical magnetic-based switch mode converter topologies; however, this requires specific shielding and component de-rating to meet the high-reliability specifications. It requires complex measurement and feedback components, and will not enable automatic re-optimization for larger changes in voltage supply or electrical loading condition. The innovation is a switch mode DC/DC power supply that eliminates the need for processors and most magnetics. It can provide a well-regulated voltage supply with a gain of 1:100 step-up to 8:1 step down, tolerating an up to 30% fluctuation of the voltage supply parameters. The circuit incorporates a ceramic core transformer in a manner that enables it to provide a well-regulated voltage output without use of any processor components or magnetic transformers. The circuit adjusts its internal parameters to re-optimize its performance for changes in supply voltage, environmental conditions, or electrical loading at the output
Kinetic energy cascades in quasi-geostrophic convection
NASA Astrophysics Data System (ADS)
Hejda, P.; Reshetnyak, M.
2012-04-01
The rapid rotation of planets causes cyclonic thermal turbulence in their cores, which may generate the large-scale magnetic fields observed outside the planets. In spite of the recent progress in modeling planetary dynamos, the models cannot cover the enormous span of scales required for a realistic parameter set. Our contribution is devoted to the study of geostrophic convection by tools of the turbulent community. This approach helps understanding of the origin of kinetic transport in the system as well as of the locality of energy transfer. We investigate numerically a model of thermal convection in two geometries: Cartesian coordinates (rectangular box) and a spherical shell. For the 3D homogeneous isotropic turbulence (in the absence of rotation) there is a direct cascade of the kinetic energy from the large scales to the small scales, where dissipation takes place. The fluxes of kinetic energy are negative for large scales and positive for small scales, i.e. the large scales are donors and provide energy to the system, whereas the small scales absorb energy. The situation changes in 2D, where the cascade of kinetic energy is inverse: from the small to the large scales. Quasi-geostrophic flow is somewhere between 3D and 2D. In such a flow, one has still 3 dimensions, but the dependence of the fields on the vertical direction along the axis of rotation is degenerated. This flow is known by its columnar structures elongated along axis of rotation. The leading order wave number corresponds to the diameter of the columns. Two cascades of the energy (direct and inverse) thus take place simultaneously (Reshetnyak and Hejda, 2008; Hejda and Reshetnyak, 2009). The spherical geometry changes partly the previous picture. Near the onset of convection, the graph of spectra of kinetic energy of quasi-geostrophic flow has saw-like shape with the largest maximum corresponding to the diameter of the vertical columns. Increase of Rayleigh number leads to the filling of the
Takekoshi, T.; Lang, F.; Strauss, C.; Denschlag, J. Hecker; Lysebo, Marius; Veseth, Leif
2011-06-15
We present the results of an experimental and theoretical study of the electronically excited (1){sup 3{Sigma}}{sub g}{sup +} state of {sup 87}Rb{sub 2} molecules. The vibrational energies are measured for deeply bound states from the bottom up to v{sup '}=15 using laser spectroscopy of ultracold Rb{sub 2} Feshbach molecules. The spectrum of each vibrational state is dominated by a 47-GHz splitting into 0{sub g}{sup -} and 1{sub g} components caused mainly by a strong second-order spin-orbit interaction. Our spectroscopy fully resolves the rotational, hyperfine, and Zeeman structure of the spectrum. We are able to describe this structure to the first order using a simplified effective Hamiltonian.
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Quasi-perpendicular/quasi-parallel divisions of Earth's bow shock
Greenstadt, E.W. )
1991-02-01
Computer-drawn diagrams of the boundaries between quasi-perpendicular and quasi-parallel areas of Earth's bow shock are displayed for a few selected cone angles of static interplanetary magnetic field (IMF). The effect on the boundary of variable IMF in the foreshock is also discussed and shown for one nominal case. The boundaries demand caution in applying them to the realistic, dynamic conditions of the solar wind and in interpreting the effects of small cone angles on the distributions of structures at the shock. However, the calculated, first-order boundaries are helpful in defining areas of the shock where contributions from active structures inherent in quasi-parallel geometry may be distinguishable from those derived secondarily from upstream reflected ion dynamics. The boundaries are also compatible with known behavior of daytime ULF geomagnetic waves and pulsations according to models postulating that cone angle-controlled, time-dependent ULF activity around the subsolar point of the bow shock provides the source of geomagnetic excitation.
Kimura, Keiji; Takehiro, Shin-ichi; Yamada, Michio
2014-08-15
We investigate properties of convective solutions of the Boussinesq thermal convection in a moderately rotating spherical shell allowing the respective rotation of the inner and outer spheres due to the viscous torque of the fluid. The ratio of the inner and outer radii of the spheres, the Prandtl number, and the Taylor number are fixed to 0.4, 1, and 500{sup 2}, respectively. The Rayleigh number is varied from 2.6 × 10{sup 4} to 3.4 × 10{sup 4}. In this parameter range, the behaviours of obtained asymptotic convective solutions are almost similar to those in the system whose inner and outer spheres are restricted to rotate with the same constant angular velocity, although the difference is found in the transition process to chaotic solutions. The convective solution changes from an equatorially symmetric quasi-periodic one to an equatorially symmetric chaotic one, and further to an equatorially asymmetric chaotic one, as the Rayleigh number is increased. This is in contrast to the transition in the system whose inner and outer spheres are assumed to rotate with the same constant angular velocity, where the convective solution changes from an equatorially symmetric quasi-periodic one, to an equatorially asymmetric quasi-periodic one, and to equatorially asymmetric chaotic one. The inner sphere rotates in the retrograde direction on average in the parameter range; however, it sometimes undergoes the prograde rotation when the convective solution becomes chaotic.
Quasi-10-day wave in the atmosphere
NASA Astrophysics Data System (ADS)
Forbes, Jeffrey M.; Zhang, Xiaoli
2015-11-01
In the classical theory of oscillations on a spherical-rotating Earth, the quasi-10-day wave (Q10DW) exists as a westward propagating "free" or "unforced" normal mode oscillation with zonal wave number s = 1. In the present study, we employ Thermosphere Ionosphere Mesosphere Energetics and Dynamics/Sounding of the Atmosphere using Broadband Emission Radiometry temperature measurements between 20 and 100 km and ±50° latitude, and extending from 2002 to 2013, to provide a comprehensive perspective on the Q10DW as it actually exists in the atmosphere. Climatological seasonal-latitudinal structures are presented which demonstrate that the Q10DW is weakest during summer months and equatorward of ±50° latitude but otherwise has amplitudes ranging from 1.0 K at ˜45 km to ˜5 K at 100 km. Seasonal asymmetries and significant interannual variability also exist. The mean period of the Q10DW is 9.8 days with a standard deviation of about 0.4 day. On average the Q10DW conforms reasonably well with theoretical expectations for a normal mode subject to the effects of dissipation and mean winds, at least below 80 km. Above 80 km this conformity often breaks down. Several factors potentially contributing to this nonconformity are discussed.
Large-scale quasi-geostrophic magnetohydrodynamics
Balk, Alexander M.
2014-12-01
We consider the ideal magnetohydrodynamics (MHD) of a shallow fluid layer on a rapidly rotating planet or star. The presence of a background toroidal magnetic field is assumed, and the 'shallow water' beta-plane approximation is used. We derive a single equation for the slow large length scale dynamics. The range of validity of this equation fits the MHD of the lighter fluid at the top of Earth's outer core. The form of this equation is similar to the quasi-geostrophic (Q-G) equation (for usual ocean or atmosphere), but the parameters are essentially different. Our equation also implies the inverse cascade; but contrary to the usual Q-G situation, the energy cascades to smaller length scales, while the enstrophy cascades to the larger scales. We find the Kolmogorov-type spectrum for the inverse cascade. The spectrum indicates the energy accumulation in larger scales. In addition to the energy and enstrophy, the obtained equation possesses an extra (adiabatic-type) invariant. Its presence implies energy accumulation in the 30° sector around zonal direction. With some special energy input, the extra invariant can lead to the accumulation of energy in zonal magnetic field; this happens if the input of the extra invariant is small, while the energy input is considerable.
Renormalized vacuum polarization of rotating black holes
NASA Astrophysics Data System (ADS)
Ferreira, Hugo R. C.
2015-04-01
Quantum field theory on rotating black hole spacetimes is plagued with technical difficulties. Here, we describe a general method to renormalize and compute the vacuum polarization of a quantum field in the Hartle-Hawking state on rotating black holes. We exemplify the technique with a massive scalar field on the warped AdS3 black hole solution to topologically massive gravity, a deformation of (2 + 1)-dimensional Einstein gravity. We use a "quasi-Euclidean" technique, which generalizes the Euclidean techniques used for static spacetimes, and we subtract the divergences by matching to a sum over mode solutions on Minkowski spacetime. This allows us, for the first time, to have a general method to compute the renormalized vacuum polarization, for a given quantum state, on a rotating black hole, such as the physically relevant case of the Kerr black hole in four dimensions.
Effects of turbulence and rotation on protostar formation as a precursor of massive black holes
NASA Astrophysics Data System (ADS)
Van Borm, C.; Bovino, S.; Latif, M. A.; Schleicher, D. R. G.; Spaans, M.; Grassi, T.
2014-12-01
Context. The seeds of the first supermassive black holes may have resulted from the direct collapse of hot primordial gas in ≳104 K haloes, forming a supermassive or quasi-star as an intermediate stage. Aims: We explore the formation of a protostar resulting from the collapse of primordial gas in the presence of a strong Lyman-Werner radiation background. Particularly, we investigate the impact of turbulence and rotation on the fragmentation behaviour of the gas cloud. We accomplish this goal by varying the initial turbulent and rotational velocities. Methods: We performed 3D adaptive mesh refinement simulations with a resolution of 64 cells per Jeans length using the ENZO code, simulating the formation of a protostar up to unprecedentedly high central densities of 1021 cm-3 and spatial scales of a few solar radii. To achieve this goal, we employed the KROME package to improve modelling of the chemical and thermal processes. Results: We find that the physical properties of the simulated gas clouds become similar on small scales, irrespective of the initial amount of turbulence and rotation. After the highest level of refinement was reached, the simulations have been evolved for an additional ~5 freefall times. A single bound clump with a radius of 2 × 10-2 AU and a mass of ~7 × 10-2 M⊙ is formed at the end of each simulation, marking the onset of protostar formation. No strong fragmentation is observed by the end of the simulations, regardless of the initial amount of turbulence or rotation, and high accretion rates of a few solar masses per year are found. Conclusions: Given such high accretion rates, a quasi-star of 105 M⊙ is expected to form within 105 years. Appendix A is available in electronic form at http://www.aanda.org
Bioreactor rotating wall vessel
NASA Technical Reports Server (NTRS)
2001-01-01
The NASA Bioreactor provides a low turbulence culture environment which promotes the formation of large, three-dimensional cell clusters. Due to their high level of cellular organization and specialization, samples constructed in the bioreactor more closely resemble the original tumor or tissue found in the body. The work is sponsored by NASA's Office of Biological and Physical Research. The bioreactor is managed by the Biotechnology Cell Science Program at NASA's Johnson Space Center (JSC). NASA-sponsored bioreactor research has been instrumental in helping scientists to better understand normal and cancerous tissue development. In cooperation with the medical community, the bioreactor design is being used to prepare better models of human colon, prostate, breast and ovarian tumors. Cartilage, bone marrow, heart muscle, skeletal muscle, pancreatic islet cells, liver and kidney are just a few of the normal tissues being cultured in rotating bioreactors by investigators. Cell constructs grown in a rotating bioreactor on Earth (left) eventually become too large to stay suspended in the nutrient media. In the microgravity of orbit, the cells stay suspended. Rotation then is needed for gentle stirring to replenish the media around the cells.
Bose-Einstein condensate in a rapidly rotating nonsymmetric trap
Fetter, Alexander L.
2010-03-15
A rapidly rotating Bose-Einstein condensate in a symmetric two-dimensional harmonic trap can be described with the lowest Landau-level set of single-particle states. The condensate wave function {psi}(x,y) is a Gaussian {proportional_to}exp(-r{sup 2}/2), multiplied by an analytic function f(z) of the complex variable z=x+iy. The criterion for a quantum phase transition to a non-superfluid correlated many-body state is usually expressed in terms of the ratio of the number of particles to the number of vortices. Here a similar description applies to a rapidly rotating nonsymmetric two-dimensional trap with arbitrary quadratic anisotropy ({omega}{sub x}{sup 2}<{omega}{sub y}{sup 2}). The corresponding condensate wave function {psi}(x,y) is a complex anisotropic Gaussian with a phase proportional to xy, multiplied by an analytic function f(z), where z=x+i{beta}{sub -}y is a stretched complex variable and 0{<=}{beta}{sub -{<=}}1 is a real parameter that depends on the trap anisotropy and the rotation frequency. Both in the mean-field Thomas-Fermi approximation and in the mean-field lowest Landau level approximation with many visible vortices, an anisotropic parabolic density profile minimizes the energy. An elongated condensate grows along the soft trap direction yet ultimately shrinks along the tight trap direction. The criterion for the quantum phase transition to a correlated state is generalized (1) in terms of N/L{sub z}, which suggests that a nonsymmetric trap should make it easier to observe this transition, or (2) in terms of a 'fragmented' correlated state, which suggests that a nonsymmetric trap should make it harder to observe this transition. An alternative scenario involves a crossover to a quasi one-dimensional condensate without visible vortices, as suggested by Aftalion et al., Phys. Rev. A 79, 011603(R) (2009).
Rotation of tokamak halo currents
Boozer, Allen H.
2012-05-15
During tokamak disruptions, halo currents, which can be tenths of the total plasma current, can flow at the plasma edge along the magnetic field lines that intercept the chamber walls. Non-axisymmetric halo currents are required to maintain force balance as the plasma kinks when the edge safety factor drops to about two in a vertical displacement event. The plasma quickly assumes a definite toroidal velocity v{sub a}(r) with respect to that of the magnetic kink, v{sub k}, where v{sub a}(r) is set by the radial electric field required for ambipolarity. The plasma velocity, v{sub pl}=v{sub a}+v{sub k}, near the edge is influenced by the interaction with neutrals and with the potential in the halo required for quasi-neutrality on open magnetic field lines, and the plasma velocity in the core is influenced by external error fields. When plasma effects dominate magnetic locking, the magnetic kink should rotate at a diamagnetic speed of either the edge or the core. If the magnetic field lines of the halo plasma intercept the wall at locations of very different electrical conductivity, the toroidal rotation of the halo currents can intermittently stall at wall locations of high conductivity. Such stalling is seen in experiments. The toroidal phase difference between the stalled halo currents and the kink, which is expected to rotate smoothly, must satisfy {delta}{phi}<{+-}{pi}/2. A concern cited by ITER engineers is that the time varying force of the rotating halo could substantially increase the disruption loads on in-vessel components.
Rotation of tokamak halo currents
NASA Astrophysics Data System (ADS)
Boozer, Allen H.
2012-05-01
During tokamak disruptions, halo currents, which can be tenths of the total plasma current, can flow at the plasma edge along the magnetic field lines that intercept the chamber walls. Non-axisymmetric halo currents are required to maintain force balance as the plasma kinks when the edge safety factor drops to about two in a vertical displacement event. The plasma quickly assumes a definite toroidal velocity va(r) with respect to that of the magnetic kink, vk, where va(r) is set by the radial electric field required for ambipolarity. The plasma velocity, vpl=va+vk, near the edge is influenced by the interaction with neutrals and with the potential in the halo required for quasi-neutrality on open magnetic field lines, and the plasma velocity in the core is influenced by external error fields. When plasma effects dominate magnetic locking, the magnetic kink should rotate at a diamagnetic speed of either the edge or the core. If the magnetic field lines of the halo plasma intercept the wall at locations of very different electrical conductivity, the toroidal rotation of the halo currents can intermittently stall at wall locations of high conductivity. Such stalling is seen in experiments. The toroidal phase difference between the stalled halo currents and the kink, which is expected to rotate smoothly, must satisfy δϕ <±π/2. A concern cited by ITER engineers is that the time varying force of the rotating halo could substantially increase the disruption loads on in-vessel components.
Broadband Rotational Spectroscopy
NASA Astrophysics Data System (ADS)
Pate, Brooks
2014-06-01
The past decade has seen several major technology advances in electronics operating at microwave frequencies making it possible to develop a new generation of spectrometers for molecular rotational spectroscopy. High-speed digital electronics, both arbitrary waveform generators and digitizers, continue on a Moore's Law-like development cycle that started around 1993 with device bandwidth doubling about every 36 months. These enabling technologies were the key to designing chirped-pulse Fourier transform microwave (CP-FTMW) spectrometers which offer significant sensitivity enhancements for broadband spectrum acquisition in molecular rotational spectroscopy. A special feature of the chirped-pulse spectrometer design is that it is easily implemented at low frequency (below 8 GHz) where Balle-Flygare type spectrometers with Fabry-Perot cavity designs become technologically challenging due to the mirror size requirements. The capabilities of CP-FTMW spectrometers for studies of molecular structure will be illustrated by the collaborative research effort we have been a part of to determine the structures of water clusters - a project which has identified clusters up to the pentadecamer. A second technology trend that impacts molecular rotational spectroscopy is the development of high power, solid state sources in the mm-wave/THz regions. Results from the field of mm-wave chirped-pulse Fourier transform spectroscopy will be described with an emphasis on new problems in chemical dynamics and analytical chemistry that these methods can tackle. The third (and potentially most important) technological trend is the reduction of microwave components to chip level using monolithic microwave integrated circuits (MMIC) - a technology driven by an enormous mass market in communications. Some recent advances in rotational spectrometer designs that incorporate low-cost components will be highlighted. The challenge to the high-resolution spectroscopy community - as posed by Frank De
Wang, Jing; Qi, Minghao; Xuan, Yi; Huang, Haiyang; Li, You; Li, Ming; Chen, Xin; Jia, Qi; Sheng, Zhen; Wu, Aimin; Li, Wei; Wang, Xi; Zou, Shichang; Gan, Fuwan
2014-11-17
A novel silicon-on-insulator (SOI) polarization splitter-rotator (PSR) with a large fabrication tolerance is proposed based on cascaded multimode interference (MMI) couplers and an assisted mode-evolution taper. The tapers are designed to adiabatically convert the input TM(0) mode into the TE(1) mode, which will output as the TE(0) mode after processed by the subsequent MMI mode converter, 90-degree phase shifter (PS) and MMI 3 dB coupler. The numerical simulation results show that the proposed device has a < 0.5 dB insertion loss with < -17 dB crosstalk in C optical communication band. Fabrication tolerance analysis is also performed with respect to the deviations of MMI coupler width, PS width, slab height and upper-cladding refractive index, showing that this device could work well even when affected by considerable fabrication errors. With such a robust performance with a large bandwidth, this device offers potential applications for CMOS-compatible polarization diversity, especially in the booming 100 Gb/s coherent optical communications based on silicon photonics technology. PMID:25402029
Wang, Jing; Qi, Minghao; Xuan, Yi; Huang, Haiyang; Li, You; Li, Ming; Chen, Xin; Jia, Qi; Sheng, Zhen; Wu, Aimin; Li, Wei; Wang, Xi; Zou, Shichang; Gan, Fuwan
2014-01-01
A novel silicon-on-insulator (SOI) polarization splitter-rotator (PSR) with a large fabrication tolerance is proposed based on cascaded multimode interference (MMI) couplers and an assisted mode-evolution taper. The tapers are designed to adiabatically convert the input TM0 mode into the TE1 mode, which will output as the TE0 mode after processed by the subsequent MMI mode converter, 90-degree phase shifter (PS) and MMI 3 dB coupler. The numerical simulation results show that the proposed device has a < 0.5 dB insertion loss with < −17 dB crosstalk in C optical communication band. Fabrication tolerance analysis is also performed with respect to the deviations of MMI coupler width, PS width, slab height and upper-cladding refractive index, showing that this device could work well even when affected by considerable fabrication errors. With such a robust performance with a large bandwidth, this device offers potential applications for CMOS-compatible polarization diversity, especially in the booming 100 Gb/s coherent optical communications based on silicon photonics technology. PMID:25402029
A 20-dB quasi-integrated horn antenna
NASA Technical Reports Server (NTRS)
Eleftheriades, George V.; Ali-Ahmad, Walid Y.; Rebeiz, Gabriel M.
1992-01-01
A multimode quasi-integrated dipole-fed horn antenna is presented with a performance comparable to that of waveguide-fed corrugated horn antennas. The antenna has been designed using fullwave analysis and has been fabricated and tested at 91 GHz. The horn has a gain of 20 dB with very symmetric patterns, a Gaussian coupling efficiency of 97 percent, and a cross-polarization level of -22.7 dB. The antenna provides a significant improvement in integrated antenna designs and is suitable for millimeter-wave communication and radar systems and as a Gaussian-beam launcher in quasi-optical receiver systems.
Solar generated quasi-biennial geomagnetic variation
NASA Technical Reports Server (NTRS)
Sugiura, M.; Poros, D. J.
1977-01-01
The existence of highly correlated quasi-biennial variations in the geomagnetic field and in solar activity is demonstrated. The analysis uses a numerical filter technique applied to monthly averages of the geomagnetic horizontal component and of the Zurich relative sunspot number. Striking correlations are found between the quasi-biennial geomagnetic variations determined from several magnetic observatories located at widely different longitudes, indicating a worldwide nature of the obtained variation. The correlation coefficient between the filtered Dst index and the filtered relative sunspot number is found to be -0.79 at confidence level greater than 99% with a time-lag of 4 months, with solar activity preceding the Dst variation. The correlation between the unfiltered data of Dst and of the sunspot number is also high with a similar time-lag. Such a timelag has not been discussed in the literature, and a further study is required to establish the mode of sun-earth relationship that gives this time delay.
Testing the quasi-absolute method in photon activation analysis
Sun, Z. J.; Wells, D.; Starovoitova, V.; Segebade, C.
2013-04-19
In photon activation analysis (PAA), relative methods are widely used because of their accuracy and precision. Absolute methods, which are conducted without any assistance from calibration materials, are seldom applied for the difficulty in obtaining photon flux in measurements. This research is an attempt to perform a new absolute approach in PAA - quasi-absolute method - by retrieving photon flux in the sample through Monte Carlo simulation. With simulated photon flux and database of experimental cross sections, it is possible to calculate the concentration of target elements in the sample directly. The QA/QC procedures to solidify the research are discussed in detail. Our results show that the accuracy of the method for certain elements is close to a useful level in practice. Furthermore, the future results from the quasi-absolute method can also serve as a validation technique for experimental data on cross sections. The quasi-absolute method looks promising.
Quasi-Monte Carlo, quasi-random numbers and quasi-error estimates
NASA Astrophysics Data System (ADS)
Kleiss, Ronald
We discuss quasi-random number sequences as a basis for numerical integration with potentially better convergence properties than standard Monte Carlo. The importance of the discrepancy as both a measure of smoothness of distribution and an ingredient in the error estimate is reviewed. It is argued that the classical Koksma-Hlawka inequality is not relevant for error estimates in realistic cases, and a new class of error estimates is presented, based on a generalization of the Woźniakowski lemma.
Quasi-Optical Transmission Line for 94-GHz Radar
NASA Technical Reports Server (NTRS)
Perez, Raul M.; Veruttipong, Watt
2008-01-01
A quasi-optical transmission line (QOTL) has been developed as a low-loss transmission line for a spaceborne cloudobserving radar instrument that operates at a nominal frequency of 94 GHz. This QOTL could also readily be redesigned for use in terrestrial millimeter-wave radar systems and millimeter-wave imaging systems. In the absence of this or another lowloss transmission line, it would be necessary to use a waveguide transmission line in the original radar application. Unfortunately, transmission losses increase and power-handling capacities of waveguides generally decrease with frequency, such that at 94 GHz, the limitation on transmitting power and the combined transmission and reception losses (greater than 5 dB) in a waveguide transmission line previously considered for the original application would be unacceptable. The QOTL functions as a very-lowloss, three-port circulator. The QOTL includes a shaped input mirror that can be rotated to accept 94-GHz transmitter power from either of two high-power amplifiers. Inside the QOTL, the transmitter power takes the form of a linearly polarized beam radiated from a feed horn. This beam propagates through a system of mirrors, each of which refocuses the beam to minimize diffraction losses. A magnetically biased ferrite disc is placed at one of the foci to utilize the Faraday effect to rotate the polarization of the beam by 45 degrees. The beam is then transmitted via an antenna system. The radar return (scatter from clouds, and/or reflections from other objects) is collected by the same antenna and propagates through the Faraday rotator in the reverse of the direction of propagation of the transmitted beam. In the Faraday rotator, the polarization of the received signal is rotated a further 45 degrees, so that upon emerging from the Faraday rotator, the received beam is polarized at 90 with respect to the transmitted beam. The transmitted and received signals are then separated by a wire-grid polarizer.
Rapidly rotating polytropes in general relativity
NASA Technical Reports Server (NTRS)
Cook, Gregory B.; Shapiro, Stuart L.; Teukolsky, Saul A.
1994-01-01
We construct an extensive set of equilibrium sequences of rotating polytropes in general relativity. We determine a number of important physical parameters of such stars, including maximum mass and maximum spin rate. The stability of the configurations against quasi-radial perturbations is diagnosed. Two classes of evolutionary sequences of fixed rest mass and entropy are explored: normal sequences which behave very much like Newtonian evolutionary sequences, and supramassive sequences which exist solely because of relativistic effects. Dissipation leading to loss of angular momentum causes a star to evolve in a quasi-stationary fashion along an evolutionary sequence. Supramassive sequences evolve towards eventual catastrophic collapse to a black hole. Prior to collapse, the star must spin up as it loses angular momentum, an effect which may provide an observational precursor to gravitational collapse to a black hole.
Radiation characteristics of quasi-periodic radio bursts in the Jovian high-latitude region
NASA Astrophysics Data System (ADS)
Kimura, Tomoki; Tsuchiya, Fuminori; Misawa, Hiroaki; Morioka, Akira; Nozawa, Hiromasa
2008-12-01
Ulysses had a "distant encounter" with Jupiter in February 2004. The spacecraft passed from north to south, and it observed Jovian radio waves from high to low latitudes (from +80° to +10°) for few months during its encounter. In this study, we present a statistical investigation of the occurrence characteristics of Jovian quasi-periodic bursts, using spectral data from the unified radio and plasma wave experiment (URAP) onboard Ulysses. The latitudinal distribution of quasi-periodic bursts is derived for the first time. The analysis suggested that the bursts can be roughly categorized into two types: one having periods shorter than 30 min and one with periods longer than 30 min, which is consistent with the results of the previous analysis of data from Ulysses' first Jovian flyby [MacDowall, R.J., Kaiser, M.L., Desch, M.D., Farrell, W.M., Hess, R.A., Stone, R.G., 1993. Quasi-periodic Jovian radio bursts: observations from the Ulysses radio and plasma wave. Experiment. Planet. Space Sci. 41, 1059-1072]. It is also suggested that the groups of quasi-periodic bursts showed a dependence on the Jovian longitude of the sub-solar point, which means that these burst groups are triggered during a particular rotational phase of the planet. Maps of the occurrence probability of these quasi-periodic bursts also showed a unique CML/MLAT dependence. We performed a 3D ray tracing analysis of the quasi-periodic burst emission to learn more about the source distribution. The results suggest that the longitudinal distribution of the occurrence probability depends on the rotational phase. The source region of quasi-periodic bursts seems to be located at an altitude between 0.4 and 1.4 Rj above the polar cap region ( L>30).
Rotational preference in gymnastics.
Heinen, Thomas; Jeraj, Damian; Vinken, Pia M; Velentzas, Konstantinos
2012-06-01
In gymnastics, most skills incorporate rotations about one or more body axes. At present, the question remains open if factors such as lateral preference and/or vestibulo-spinal asymmetry are related to gymnast's rotational preference. Therefore, we sought to explore relationships in gymnast's rotation direction between different gymnastic skills. Furthermore, we sought to explore relationships between rotational preference, lateral preference, and vestibulo-spinal asymmetry. In the experiment n = 30 non-experts, n = 30 near-experts and n = 30 experts completed a rotational preference questionnaire, a lateral preference inventory, and the Unterberger-Fukuda Stepping Test. The results revealed, that near-experts and experts more often rotate rightward in the straight jump with a full turn when rotating leftward in the round-off and vice versa. The same relationship was found for experts when relating the rotation preference in the handstand with a full turn to the rotation preference in the straight jump with a full turn. Lateral preference was positively related to rotational preference in non-expert gymnasts, and vestibulo-spinal asymmetry was positively related to rotational preference in experts. We suggest, that gymnasts should explore their individual rotational preference by systematically practicing different skills with a different rotation direction, bearing in mind that a clearly developed structure in rotational preference between different skills may be appropriate to develop more complex skills in gymnastics. PMID:23486362
Rotational Preference in Gymnastics
Heinen, Thomas; Jeraj, Damian; Vinken, Pia M.; Velentzas, Konstantinos
2012-01-01
In gymnastics, most skills incorporate rotations about one or more body axes. At present, the question remains open if factors such as lateral preference and/or vestibulo-spinal asymmetry are related to gymnast’s rotational preference. Therefore, we sought to explore relationships in gymnast’s rotation direction between different gymnastic skills. Furthermore, we sought to explore relationships between rotational preference, lateral preference, and vestibulo-spinal asymmetry. In the experiment n = 30 non-experts, n = 30 near-experts and n = 30 experts completed a rotational preference questionnaire, a lateral preference inventory, and the Unterberger-Fukuda Stepping Test. The results revealed, that near-experts and experts more often rotate rightward in the straight jump with a full turn when rotating leftward in the round-off and vice versa. The same relationship was found for experts when relating the rotation preference in the handstand with a full turn to the rotation preference in the straight jump with a full turn. Lateral preference was positively related to rotational preference in non-expert gymnasts, and vestibulo-spinal asymmetry was positively related to rotational preference in experts. We suggest, that gymnasts should explore their individual rotational preference by systematically practicing different skills with a different rotation direction, bearing in mind that a clearly developed structure in rotational preference between different skills may be appropriate to develop more complex skills in gymnastics. PMID:23486362
Quasi-Heterodyne Hologram Interferometry
NASA Astrophysics Data System (ADS)
Hariharan, P.
1985-08-01
Wider use of hologram interferometry for quantitative measure-ments has been delayed by the fact that interpolation between the fringe maxima and minima to obtain the optical path difference at a particular point in the field is laborious and inaccurate. A solution to this problem is quasi-hetero-dyne interferometry, which permits rapid and accurate measurements simultaneously at a number of points distributed over the interference pattern. In this technique a television camera is used in conjunction with digital electronics to measure and store the irradiance values at points on a rectangular sampling grid covering the real-time interference fringes. The phase difference between the interfering wavefronts at each point is then calculated from the irradiance values obtained from successive scans of the camera made while the phase of one of the wavefronts is shifted either continuously or in steps. A practical system is described with which values of the optical path difference for 10,000 data points can be obtained with an accuracy of +/- A/200 in less than 10 s. The application of quasi-heterodyne hologram interferometry to the measurement of vector displacements and to holographic contouring is discussed.
On the rotation of viscoelastic satellites
NASA Astrophysics Data System (ADS)
Noyelles, Benoit
2016-05-01
Most of the natural satellites are thought to be synchronous. For some of them, the presence of a thin, outer crust coating a global ocean motivates the consideration of their elasticity for modeling their rotation. Some attempts have been made to include it as an additional effect in the rotational theories.Actually, the shapes of these bodies are partly fossil, partly due to internal processes, and partly due to the tidal and rotational distortions, driving them to the hydrostatic equilibrium.I here present a fully consistent model of viscoelastic rotation of these bodies, in which the tensor of inertia is time-dependent and ruled by these distorting effects. The influence of the different frequencies affecting the motion of the satellite and the tidal parameters is considered. For that, I use an iterative numerical algorithm, in which the tensor of inertia and the rotational variables are decomposed under a quasi-periodic form. The motion of the satellite is modeled with planetary ephemerides, and the frequency-dependency of the tides is based on the Maxwell model. This results in an improved theory of the librations and the obliquity, which I validate by analytical calculations. I show that not only the amplitudes of these quantities are affected, but also their phases. I finally apply this theory on Mimas and Epimetheus, for which librations have been measured. This implies an updated interpretation of their interiors.
Active longitudes: Structure, dynamics, and rotation
NASA Astrophysics Data System (ADS)
Ivanov, E. V.
Greenwich data for 1879-2005 (cycles 12-23) are used to study the longitude distribution of sunspot group areas summed over a Carrington rotation s(CR) separately in the southern and northern hemispheres. The zones of active longitudes (AL) are identified, and their behaviour (location, shift, and intensity variations) is analyzed over the time interval under consideration. In particular, we have studied the active longitudes in two reference frames corresponding to the rotation periods T = 27.2753 and T = 27.00 days. The AL zones are shown to consist of a set of individual narrow sunspot formation zones rotating rigidly with the Carrington period T ˜ 27.2753 days. The lifetime of the sunspot formation zones exceeds significantly that of individual sunspots and may reach 15-20 rotations. Besides the rigidly rotating active longitudes we have revealed the active longitudes that migrate in the Carrington reference frame at different (greater and smaller than Carrington) angular velocities. Quasi-biennial oscillations (QBO) of the total sunspot areas in the northern and southern longitudinal sectors corresponding to AL zones are studied for the period 1879-2004 using the spectral and correlation analysis methods. The relationships between the antipodal, symmetric about the equator, and adjoining AL zones are analyzed.
Development of quasi-isodynamic stellarators
NASA Astrophysics Data System (ADS)
Nührenberg, Jürgen
2010-12-01
Theoretical stellarator research from MHD-stable stellarators via quasi-helically symmetric ones to Wendelstein 7-X, quasi-axisymmetric tokamaks and quasi-isodynamic stellarators is sketched. Research strategy, computational aspects and various favorable properties are emphasized. The results found, but only together with the completion of according experimental devices and their scientific exploitation, may form a basis for selecting the confinement geometry most viable for fusion.
Hydrogen rotation-vibration oscillator
Rhodes, C.K.
1974-01-29
A laser system is described wherein molecular species of hydrogen and hydrogen isotopes are induced to oscillate on rotational-vibrational levels by subjecting the hydrogen to a transverse beam of electrons of a narrowly defined energy between about 1 and 5 eV, thereby producing high intensity and high energy output. (Official Gazette)
NASA Astrophysics Data System (ADS)
Cave, Robert J.; Stanton, John F.
2016-02-01
We present a simple quasi-diabatization scheme applicable to spectroscopic studies that can be applied using any wavefunction for which one-electron properties and transition properties can be calculated. The method is based on rotation of a pair (or set) of adiabatic states to minimize the difference between the given transition property at a reference geometry of high symmetry (where the quasi-diabatic states and adiabatic states coincide) and points of lower symmetry where quasi-diabatic quantities are desired. Compared to other quasi-diabatization techniques, the method requires no special coding, facilitates direct comparison between quasi-diabatic quantities calculated using different types of wavefunctions, and is free of any selection of configurations in the definition of the quasi-diabatic states. On the other hand, the method appears to be sensitive to multi-state issues, unlike recent methods we have developed that use a configurational definition of quasi-diabatic states. Results are presented and compared with two other recently developed quasi-diabatization techniques.
NASA Astrophysics Data System (ADS)
Trubnikov, B. A.; Zhdanov, S. K.
1987-11-01
The present work shows that in the long-wave approximation many-about 30-unstable media are described by the equations >ϱdot;=-ϱ divoverlineν, overline∸ =c 20m∇ϱ {1}/{m}which differ from the equations of ideal gas motion only in the sign on the right-hand side. Various quantities can be taken as an “effective density” ϱ and the parameter m, referred to as the “azimuthal number”, is generally an integer or half-integer varying as m=-2, -1, {-1}/{2}, {1}/{2}, 1, {3}/{2}. Historically, the earliest example of the systems under consideration is the hypothetical “Chaplygin gas”, i.e. a gas with the adiabetic exponent γ=-1, which corresponds to the azimuthal number m= {-1}/{2} (it was studied by S.A. Chaplygin in 1896-1902). That is why the authors refer to such media as “quasi-gas” or “quasi-Chaplygin” media. They include, in particular, the “overturned shallow water”, constrictions on current-carrying pinches, self-focusing of light, the Buneman, modulation and tearing instabilities in plasmas, as well as many other instabilities. Similar “quasi-Chaplygin” equations describe perturbations of various solitons, such as the Korteweg-de Vries and Kadomtsev-Petviashvili solitons, those of the non-linear Schrödinger equations, as well as cnoidal waves. These equations are shown to have particular self-similar solutions of the form ν∼ r/ t in the multi-dimensional case. Of greater interest, however, is the possibility of their complete integrability under any initial conditions either in a one-dimensional unsteady-state case when ϱ= ϱ( t, x) or in a two-dimensional steady-state case when ϱ= ϱ( x, y). In these cases, the original non-linear equations are reduced by hodograph transformations to two linear equations and then to the classical Laplace equation ∇ 2ψ( r, ϕ, z)=0 in a certain three-dimensional “phase” space. The two simplest “electrostatic” solutions-the Coulomb and dipole ones-give four forms of the most
Power Harvesting from Rotation?
ERIC Educational Resources Information Center
Chicone, Carmen; Feng, Z. C.
2008-01-01
We show the impossibility of harvesting power from rotational motions by devices attached to the rotating object. The presentation is suitable for students who have studied Lagrangian mechanics. (Contains 2 figures.)
Robust rotational-velocity-Verlet integration methods
NASA Astrophysics Data System (ADS)
Rozmanov, Dmitri; Kusalik, Peter G.
2010-05-01
Two rotational integration algorithms for rigid-body dynamics are proposed in velocity-Verlet formulation. The first method uses quaternion dynamics and was derived from the original rotational leap-frog method by Svanberg [Mol. Phys. 92, 1085 (1997)]; it produces time consistent positions and momenta. The second method is also formulated in terms of quaternions but it is not quaternion specific and can be easily adapted for any other orientational representation. Both the methods are tested extensively and compared to existing rotational integrators. The proposed integrators demonstrated performance at least at the level of previously reported rotational algorithms. The choice of simulation parameters is also discussed.
Trirotron: triode rotating beam radio frequency amplifier
Lebacqz, Jean V.
1980-01-01
High efficiency amplification of radio frequencies to very high power levels including: establishing a cylindrical cloud of electrons; establishing an electrical field surrounding and coaxial with the electron cloud to bias the electrons to remain in the cloud; establishing a rotating electrical field that surrounds and is coaxial with the steady field, the circular path of the rotating field being one wavelength long, whereby the peak of one phase of the rotating field is used to accelerate electrons in a beam through the bias field in synchronism with the peak of the rotating field so that there is a beam of electrons continuously extracted from the cloud and rotating with the peak; establishing a steady electrical field that surrounds and is coaxial with the rotating field for high-energy radial acceleration of the rotating beam of electrons; and resonating the rotating beam of electrons within a space surrounding the second field, the space being selected to have a phase velocity equal to that of the rotating field to thereby produce a high-power output at the frequency of the rotating field.
Quasi-steady plasma acceleration.
NASA Technical Reports Server (NTRS)
Jahn, R. G.; Von Jaskowsky, W. F.; Clark, K. E.
1973-01-01
A coaxial plasma accelerator driven by protracted pulses of current in the range of 10,000 to 100,000 A and synchronized mass flows from 1.0 to 36 g/sec argon attains, after some tens of microseconds, a stable magnetoplasmadynamic acceleration mode. This 'quasi-steady' discharge form is characterized by constant terminal voltage and current, a diffuse, fixed current distribution within the discharge, and a steady plasma efflux at velocities of approximately 20 km/sec. Measured potential distributions reveal that the bulk of the arc voltage gradient, exclusive of the electrode falls, occurs within two diameters of the cathode, and is normal to it. The anode fall voltage varies inversely with local current density, implying substantially lower anode losses at higher power arc operation. Spectroscopic, potential, and velocity measurements indicate the existence of a characteristic mass flow rate for a given current, below which arc operation becomes erratic.
Rotations with Rodrigues' Vector
ERIC Educational Resources Information Center
Pina, E.
2011-01-01
The rotational dynamics was studied from the point of view of Rodrigues' vector. This vector is defined here by its connection with other forms of parametrization of the rotation matrix. The rotation matrix was expressed in terms of this vector. The angular velocity was computed using the components of Rodrigues' vector as coordinates. It appears…
Mechanism of rotational relaxation.
NASA Technical Reports Server (NTRS)
Polanyi, J. C.; Woodall, K. B.
1972-01-01
A model is presented which describes the characteristic pattern of relaxation of a nonthermal rotational distribution of hydrogen halide, peaked initially at high rotational quantum number J, to a thermal distribution without generating a peak at intermediate J. A method for correcting infrared chemiluminiscence data for modest rotational relaxation is also suggested.
Minimax discrimination of quasi-Bell states
Kato, Kentaro
2014-12-04
An optimal quantum measurement is considered for the so-called quasi-Bell states under the quantum minimax criterion. It is shown that the minimax-optimal POVM for the quasi-Bell states is given by its square-root measurement and is applicable to the teleportation of a superposition of two coherent states.
Physics of untied rotating space elevators
NASA Astrophysics Data System (ADS)
Knudsen, Steven; Golubović, Leonardo
2015-12-01
We explore fundamental aspects of the physics of a novel class of dynamical systems, Rotating Space Elevators (RSE) (L. Golubović, S. Knudsen, Europhys. Lett. 86, 34001 (2009) and S. Knudsen, L. Golubović, Eur. Phys. J. Plus 129, 242 (2014)). An RSE is a loopy string reaching deep into outer space. The floppy RSE loop executes a double rotating motion due to which the objects sliding along the RSE string (climbers) can be transported far away from the Earth's surface without using internal engines or propulsion. By extensive numerical simulations and analytic calculations, this study addresses an interesting and provocative question at the very heart of the RSE physics: What will happen if one unties the rotating space elevator from the Earth? We find that the untied RSE exhibits rich nonlinear dynamics. In particular, strikingly, we find that the untied RSE may still behave as if it were tied to the planet. Such a quasi-tied yet untied RSE remains close to the Earth and exhibits persistent shape and enduring double rotating motion. Moreover, the climbers sliding along such a quasi-tied RSE move in much the same way as they do along a tied RSE. Under some conditions however we find that the untied RSE may undergo an instability leading it to a dynamical state in which the RSE hops well above the Earth surface. By changing the untied RSE parameters, the maximum height reached during hopping may be made to diverge. Such an untied RSE unbinds from the Earth to infinity, i.e., to interplanetary space.
Coffman, R.T.
1957-12-10
A seal is described for a rotatable shaft that must highly effective when the shaft is not rotating but may be less effective while the shaft is rotating. Weights distributed about a sealing disk secured to the shaft press the sealing disk against a tubular section into which the shiilt extends, and whem the shaft rotates, the centrifugal forces on the weights relieve the pressurc of the sealing disk against the tubular section. This action has the very desirible result of minimizing the wear of the rotating disk due to contact with the tubular section, while affording maximum sealing action when it is needed.
Quasi-Freestanding multilayer graphene films on the carbon face of SiC
Siegel, D. A.; Hwang, C. G.; Fedorov, A. V.; Lanzara, A.
2010-06-30
The electronic band structure of as-grown and doped graphene grown on the carbon face of SiC is studied by high-resolution angle-resolved photoemission spectroscopy, where we observe both rotations between adjacent layers and AB-stacking. The band structure of quasi-freestanding AB-bilayers is directly compared with bilayer graphene grown on the Si-face of SiC to study the impact of the substrate on the electronic properties of epitaxial graphene. Our results show that the C-face films are nearly freestanding from an electronic point of view, due to the rotations between graphene layers.
Photonic quasi-crystals in Fourier and Fourier-Bessel space
NASA Astrophysics Data System (ADS)
Newman, S. R.; Gauthier, R. C.
2013-02-01
Photonic crystals that are aperiodic or quasi-crystalline in nature have been the focus of research due to their complex spatial distributions, resulting in high order rotational symmetries. Recently we proposed aperiodic patterns that were rotationally symmetric while being random in the radial direction. The structures are designed by segmenting the circular design space, randomly populating one segment, and repeating that segment about a center of rotation. Studying the symmetries and geometrical attributes of aperiodic structures is typically performed in reciprocal Fourier space by examining the distribution of the Fourier coefficients. This allows the translational symmetry to be directly extracted and the rotational nature to be interpreted. Instead we propose comparing the typical Fourier analysis with the use of a Fourier-Bessel space. The Fourier-Bessel approach expands the dielectric layout in cylindrical coordinates using exponential and Bessel functions as the angular and radial basis functions. The coefficients obtained in this fashion directly provide the rotational symmetries that are present. This work will examine both the Fourier and Fourier-Bessel distributions of the proposed structures as well as other quasi-crystals in order to explore the strengths and weaknesses of both techniques.
Quasi experimental designs in pharmacist intervention research.
Krass, Ines
2016-06-01
Background In the field of pharmacist intervention research it is often difficult to conform to the rigorous requirements of the "true experimental" models, especially the requirement of randomization. When randomization is not feasible, a practice based researcher can choose from a range of "quasi-experimental designs" i.e., non-randomised and at time non controlled. Objective The aim of this article was to provide an overview of quasi-experimental designs, discuss their strengths and weaknesses and to investigate their application in pharmacist intervention research over the previous decade. Results In the literature quasi experimental studies may be classified into five broad categories: quasi-experimental design without control groups; quasi-experimental design that use control groups with no pre-test; quasi-experimental design that use control groups and pre-tests; interrupted time series and stepped wedge designs. Quasi-experimental study design has consistently featured in the evolution of pharmacist intervention research. The most commonly applied of all quasi experimental designs in the practice based research literature are the one group pre-post-test design and the non-equivalent control group design i.e., (untreated control group with dependent pre-tests and post-tests) and have been used to test the impact of pharmacist interventions in general medications management as well as in specific disease states. Conclusion Quasi experimental studies have a role to play as proof of concept, in the pilot phases of interventions when testing different intervention components, especially in complex interventions. They serve to develop an understanding of possible intervention effects: while in isolation they yield weak evidence of clinical efficacy, taken collectively, they help build a body of evidence in support of the value of pharmacist interventions across different practice settings and countries. However, when a traditional RCT is not feasible for
The Supine Internal Rotation Test
Moulton, Samuel G.; Cram, Tyler R.; James, Evan W.; Dornan, Grant J.; Kennedy, Nicholas I.; LaPrade, Robert F.
2015-01-01
Background: Biomechanical studies have reported that the posterior cruciate ligament (PCL) functions as a restraint against excessive tibial internal rotation at higher degrees of knee flexion. Purpose: To investigate the use of a supine internal rotation (IR) test for the diagnosis of grade III PCL injuries. The hypothesis was that internal rotation would be greater in patients with grade III PCL injuries compared with other knee injuries and that the supine IR test would demonstrate excellent diagnostic accuracy. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: A consecutive series of 309 patients underwent arthroscopic and/or open knee ligament reconstruction surgery. Seven patients were excluded based on the inability to perform a side-to-side comparison of internal rotation. Tibial internal rotation was assessed bilaterally on 302 patients during examination under anesthesia by a single orthopaedic surgeon measuring tibial tubercle excursion (mm) while applying internal rotation torque. Internal rotation was graded from 0 to 4 at 60°, 75°, 90°, 105°, and 120° of knee flexion. Data were collected and stored prospectively. The optimal threshold for the supine IR test was chosen based on maximization of the Youden index. Diagnostic accuracy parameters were calculated. Multiple logistic regression models were constructed to assess the influence of other knee pathologies on diagnostic accuracy. Results: Examination of the 22 PCL-deficient knees demonstrated an increase in tibial internal rotation at 60°, 75°, 90°, 105°, and 120° of knee flexion. The supine IR test had a sensitivity of 95.5%, a specificity of 97.1%, a positive predictive value of 72.4%, and a negative predictive value of 99.6% for the diagnosis of grade III PCL injuries. Posterolateral corner injury had a significant interaction with the supine IR test, increasing its sensitivity and decreasing its specificity. Conclusion: PCL-deficient knees demonstrated an increase
Quasi-local conserved charges in Lorenz-diffeomorphism covariant theory of gravity
NASA Astrophysics Data System (ADS)
Adami, H.; Setare, M. R.
2016-04-01
In this paper, using the combined Lorenz-diffeomorphism symmetry, we find a general formula for the quasi-local conserved charge of the covariant gravity theories in a first order formalism of gravity. We simplify the general formula for the Lovelock theory of gravity. Afterwards, we apply the obtained formula on BHT gravity to obtain the energy and angular momentum of the rotating OTT black hole solution in the context of this theory.
A fully implicit method for 3D quasi-steady state magnetic advection-diffusion.
Siefert, Christopher; Robinson, Allen Conrad
2009-09-01
We describe the implementation of a prototype fully implicit method for solving three-dimensional quasi-steady state magnetic advection-diffusion problems. This method allows us to solve the magnetic advection diffusion equations in an Eulerian frame with a fixed, user-prescribed velocity field. We have verified the correctness of method and implementation on two standard verification problems, the Solberg-White magnetic shear problem and the Perry-Jones-White rotating cylinder problem.
On Obliquely Magnetized and Differentially Rotating Stars
NASA Astrophysics Data System (ADS)
Wei, Xing; Goodman, Jeremy
2015-06-01
We investigate the interaction of differential rotation and a misaligned magnetic field. The incompressible magnetohydrodynamic equations are solved numerically for a free-decay problem. In the kinematic limit, differential rotation annihilates the non-axisymmetric field on a timescale proportional to the cube root of magnetic Reynolds number (Rm), as predicted by Rädler. Nonlinearly, the outcome depends upon the initial energy in the non-axisymmetric part of the field. Sufficiently weak fields approach axisymmetry as in the kinematic limit; some differential rotation survives across magnetic surfaces, at least on intermediate timescales. Stronger fields enforce uniform rotation and remain non-axisymmetric. The initial field strength that divides these two regimes does not follow the scaling R{{m}-1/3} predicted by quasi-kinematic arguments, perhaps because our Rm is never sufficiently large or because of reconnection. We discuss the possible relevance of these results to tidal synchronization and tidal heating of close binary stars, particularly double white dwarfs.
Resonance tongues in the quasi-periodic Hill-Schrödinger equation with three frequencies
NASA Astrophysics Data System (ADS)
Puig, Joaquim; Simó, Carles
2011-02-01
In this paper we investigate numerically the following Hill's equation x″ + ( a + bq( t)) x = 0 where q(t) = \\cos t + \\cos sqrt {2t} + \\cos sqrt {3t} is a quasi-periodic forcing with three rationally independent frequencies. It appears, also, as the eigenvalue equation of a Schrödinger operator with quasi-periodic potential. Massive numerical computations were performed for the rotation number and the Lyapunov exponent in order to detect open and collapsed gaps, resonance tongues. Our results show that the quasi-periodic case with three independent frequencies is very different not only from the periodic analogs, but also from the case of two frequencies. Indeed, for large values of b the spectrum contains open intervals at the bottom. From a dynamical point of view we numerically give evidence of the existence of open intervals of a, for large b, where the system is nonuniformly hyperbolic: the system does not have an exponential dichotomy but the Lyapunov exponent is positive. In contrast with the region with zero Lyapunov exponents, both the rotation number and the Lyapunov exponent do not seem to have square root behavior at endpoints of gaps. The rate of convergence to the rotation number and the Lyapunov exponent in the nonuniformly hyperbolic case is also seen to be different from the reducible case.
Modular Coils and Plasma Configurations for Quasi-axisymmetric Stellarators
L.P. Ku and A.H. Boozer
2010-09-10
Characteristics of modular coils for quasi-axisymmetric stellarators that are related to the plasma aspect ratio, number of field periods and rotational transform have been examined systematically. It is observed that, for a given plasma aspect ratio, the coil complexity tends to increase with the increased number of field periods. For a given number of field periods, the toroidal excursion of coil winding is reduced as the plasma aspect ratio is increased. It is also clear that the larger the coil-plasma separation is, the more complex the coils become. It is further demonstrated that it is possible to use other types of coils to complement modular coils to improve both the physics and the modular coil characteristics.
Quasi steady MPD performance analysis
NASA Astrophysics Data System (ADS)
Guarducci, F.; Paccani, G.; Lehnert, J.
2011-04-01
Pulsed (quasi-steady) solid propellant magnetoplasmadynamic thruster operation has been investigated both in the self-induced and applied magnetic field cases. Input parameters have been varied in order to analyze performance (in particular impulse bit) dependance on these parameters. The stored energy per shot has been set to four values between 2000 and 3000 J, while magnetic field has been set to six values between 0 and 159 mT. Impulse bit has been evaluated through a thrust stand technique: a brief overview of this method is given together with a description of the data processing procedure. Current measurements allow to use Maeker's formula as a reference for comparison between theoretical and empirical results as well as between self and applied field operation. Appreciable improvements of the thruster impulse bit performance have been noticed for defined sets of stored energy and applied field values. An inductive interaction between the magnet coil and the laboratory facilities, resulting in thrust stand displacement, has been observed: this phenomenon and its consequences on measurements have been investigated. A target used as a ballistic pendulum, insensitive to magnetic coupling, has been employed to acquire a new set of measurements: the results obtained with the target technique show a maximum discrepancy of 5% when compared with the measurements derived from the thrust stand technique. Finally, the thrust stand measurements appear to be affected by the inductive interactions only for very high values of the applied field.
Analysis of the FASSST rotational spectrum of NCNCS in view of quantum monodromy.
Winnewisser, Brenda P; Winnewisser, Manfred; Medvedev, Ivan R; De Lucia, Frank C; Ross, Stephen C; Koput, Jacek
2010-08-01
Quantum monodromy has a strong impact on the ro-vibrational energy levels of chain molecules whose bending potential energy function has the form of the bottom of a champagne bottle (i.e. with a hump or punt) around the linear configuration. NCNCS, cyanogen iso-thiocyanate, is a particularly good example of such a molecule and clearly exhibits a distinctive monodromy-induced dislocation of the energy level pattern at the bending-rotation energy at the top of the potential energy hump. Indeed, NCNCS [B. P. Winnewisser et al., Phys. Rev. Lett. 2005, 95, 243002] and the water molecule [N. F. Zobov et al., Chem. Phys. Lett. 2005, 414, 193-197] were the first two molecules for which experimental confirmation of quantum monodromy was obtained. We used the fast scan sub-millimetre spectroscopic technique (FASSST) to extend the measurements and spectral analysis to pure rotational transitions (end-over-end) in bending vibrational states lying well above the monodromy point. The analysis of 9204 lines assigned to 7 vibrational states, presented here, shows that the topological properties of the bending potential function are mapped onto every aspect of the ro-vibrational energy levels involving excitation of the quasi-linear bending vibration. In order to model the large amplitude dynamics of such a molecular system, and also to achieve some insight beyond satisfactory parameters for reproducing the spectrum, we used the generalized semi-rigid bender (GSRB) Hamiltonian, which is described in some detail. This Hamiltonian provides a good description of the energy levels over the seven bending states observed, coming close to experimental accuracy. Due to high J values of the measured rotational transitions (J
Three-Dimensional Modeling of Quasi-Homologous Solar Jets
NASA Technical Reports Server (NTRS)
Pariat, E.; Antiochos, S. K.; DeVore, C. R.
2010-01-01
Recent solar observations (e.g., obtained with Hinode and STEREO) have revealed that coronal jets are a more frequent phenomenon than previously believed. This higher frequency results, in part, from the fact that jets exhibit a homologous behavior: successive jets recur at the same location with similar morphological features. We present the results of three-dimensional (31)) numerical simulations of our model for coronal jets. This study demonstrates the ability of the model to generate recurrent 3D untwisting quasi-homologous jets when a stress is constantly applied at the photospheric boundary. The homology results from the property of the 3D null-point system to relax to a state topologically similar to its initial configuration. In addition, we find two distinct regimes of reconnection in the simulations: an impulsive 3D mode involving a helical rotating current sheet that generates the jet, and a quasi-steady mode that occurs in a 2D-like current sheet located along the fan between the sheared spines. We argue that these different regimes can explain the observed link between jets and plumes.
THREE-DIMENSIONAL MODELING OF QUASI-HOMOLOGOUS SOLAR JETS
Pariat, E.; Antiochos, S. K.; DeVore, C. R.
2010-05-10
Recent solar observations (e.g., obtained with Hinode and STEREO) have revealed that coronal jets are a more frequent phenomenon than previously believed. This higher frequency results, in part, from the fact that jets exhibit a homologous behavior: successive jets recur at the same location with similar morphological features. We present the results of three-dimensional (3D) numerical simulations of our model for coronal jets. This study demonstrates the ability of the model to generate recurrent 3D untwisting quasi-homologous jets when a stress is constantly applied at the photospheric boundary. The homology results from the property of the 3D null-point system to relax to a state topologically similar to its initial configuration. In addition, we find two distinct regimes of reconnection in the simulations: an impulsive 3D mode involving a helical rotating current sheet that generates the jet and a quasi-steady mode that occurs in a 2D-like current sheet located along the fan between the sheared spines. We argue that these different regimes can explain the observed link between jets and plumes.
Global Rotation of Non-Rotating Origin
NASA Astrophysics Data System (ADS)
Fukushima, T.
2001-11-01
At its 24th General Assembly held at Manchester last year, the IAU has adopted the Celestial Ephemeris Origin (CEO) as a new longitude origin of the celestial coordinate system (Capitaine et al. 2000, IAU 2001). The CEO is the application of Guinot's non-rotating origin (NRO) to the Earth's equator (Guinot 1979, Capitaine et al. 1986, Capitaine 1990). By using the current IAU precession/nutation theory, we integrated the global orbit of CEO. It is a slightly curved zigzag pattern of the amplitude of around 23o moving secularly along the ecliptic. Among its kinematical features, we note that CEO has a large secular component of rotation with respect to the inertial reference frame. The current speed of this global rotation is as large as around -4.15 ''/yr. The negative sign shows that CEO rotates clockwise with respect to the inertial frame when viewed from the north celestial pole. Unfortunately this is a general property of NROs. On the other hand, such secular rotation does not exist for some geometrically-defined longitude origins like K, H, and Σ already discussed in Kovalevsky and McCarthy (1998). We think that the existence of a global secular rotaion means that the CEO, and NROs in general, is not appropriate to be specified as the x-axis of celestial coordinate systems.
Rotational dynamics of methyl groups in m-xylene
NASA Astrophysics Data System (ADS)
Kirstein, O.; Prager, M.; Dimeo, R. M.; Desmedt, A.
2005-01-01
Methyl group dynamics of m-xylene was investigated by using incoherent inelastic and quasi-elastic neutron scattering. Inelastic measurements were carried out at the high flux backscattering spectrometer HFBS at the National Institute of Standards, quasi-elastic measurements at the time-of-flight spectrometer NEAT at the Hahn-Meitner-Institute. Rotational potentials are derived which describe the tunnel splittings, first librational, and activation energies of the two inequivalent CH3 groups. Indications for coupling of the methyl rotation to low-energy phonons have been found. The finite width of one tunneling transition at He temperature is described by direct methyl-methyl coupling. The combined results of the experiments and the calculations allow a unique assignment of rotor excitations to crystallographic sites.
Quasi-static self-powered sensing and data logging
NASA Astrophysics Data System (ADS)
Lajnef, Nizar; Chakrabartty, Shantanu; Burgueño, Rigoberto; Borchani, Wassim
2014-04-01
Many signals of interest in the assessment of structural systems lie in the quasi-static range (frequency << 1Hz). This poses a significant challenge for the development of self-powered sensors that are required not only to monitor these events but also to harvest the energy for sensing, computation and storage from the signal being monitored. This paper combines the use of mechanically-equivalent frequency modulators and piezo-powered threshold detection modules capable of computation and data storage with a total current less than 10nA. The system is able to achieve events counting for input deformations at frequencies lower than 0.1Hz. The used mechanically-equivalent frequency modulators allow the transformation of the low-amplitude and low-rate quasi-static deformations into an amplified input to a piezoelectric transducer. The sudden transitions in unstable mode branch switching, during the elastic postbuckling response of slender columns and plates, are used to generate high-rate deformations. Experimental results show that an oscillating semi-crystalline plastic polyvinylidene fluoride (PVDF), attached to the up-converting modules, is able to generate a harvestable energy at levels between 0.8μJ to 2μJ. In this work, we show that a linear injection response of our combined frequency up-converter / piezo-floating-gate sensing system can be used for self-powered measurement and recording of quasi-static deformations levels. The experimental results demonstrate that a sensor fabricated in a 0.5- μm CMOS technology can count and record the number of quasi-static input events, while operating at a power level significantly lower than 1μW.
Research on the characteristics of quasi-steady cavitation in a centrifugal pump
NASA Astrophysics Data System (ADS)
Lu, J. X.; Yuan, S. Q.; Li, X. J.; Si, Q. R.; Luo, Y.
2015-01-01
With the pressure decreasing, the process of cavitation in a centrifugal pump could be summarized as incipient cavitation, quasi-steady cavitation and unsteady cavitation. Quasi-steady cavitation is the condition that is between the incipient cavitation and unsteady cavitation in a centrifugal pump. Under this condition, the intensity of cavitation is relatively weak, and the head of the pump almost remains unchanged, but the cavitation exists, causing damage to the impeller by pitting and erosion. So it is important to investigate the quasi-steady cavitation. In this paper, both the numerical and experimental methods had been carried out to investigate the characteristics of quasi-steady cavitation. The internal flow in the pump, the performance of cavitation and the inlet and outlet pressure pulsation of the pump measured through experimental method have been studied under different NPSHa conditions. It was found that the head decreases about 0.77%-1.38% from non-cavitation condition and it could be regarded as the quasi-steady cavitation. Little change has been found from the internal flow between non-cavitation condition and quasi-steady cavitation condition. The period of inlet pressure pulsation changes from the time that the blade passes by to the period of shaft rotating with the development of cavitation. The dominant frequency of the inlet pressure pulsation is two times of shaft frequency whose amplitudes decrease firstly and then increase to a peak value, followed by a decrease to a low value in quasi-steady cavitation conditions. The dominant frequency of the outlet pressure pulsation is blade passing frequency whose amplitudes increase firstly and then decrease gradually with the decrease of NPSHa.