ERIC Educational Resources Information Center
Gillespie, A.
1975-01-01
Describes a method for the determination of the velocity of sound using a dual oscilloscope on which is displayed the sinusoidal input into a loudspeaker and the signal picked up by a microphone. (GS)
Sediment sound velocities from sonobuoys: Arabian fan
Bachman, R.T.; Hamilton, E.L.
1980-02-10
Eight variable-angle seismic reflection stations in the Arabian Fan, Northwestern Indian Ocean, provided 40 determinations of sound velocity in sediment and sedimentary rock. Sound velocity in the homogeneous, largely terrigenous fan increases smoothly with depth. Regression analysis yielded the velocity-time relationship V (km/s)=1.510+1.863t, where V is instantaneous velocity and t is one-way travel time below the sea floor to 1 s. The velocity-depth function is V (km/s)=1.510+1.200h-0.253h/sup 2/+ 0.034h/sup 3/, where h is subbottom depth in km.
Estimating organic chain length through sound velocity measurements.
Povey, Malcolm J W; Stec, Zoe; Hindle, Scott A; Kennedy, John D; Taylor, Richard G
2005-02-01
The ability to measure the length of polymers while monitoring their production is evidently extremely valuable, but is also a useful tool for chemical identification purposes at other times, e.g. the analysis of waste water. A study of the relationship between velocity of sound and chain length has been carried out. Initial studies were performed on two model systems; a series of pure liquid n-alkanes (pentane to hexadecane) and 1-alcohols (methanol to 1-dodecanol). This study was extended to look at an industrially significant system of dimethylsiloxanes 200 fluid (L2, 0.65 cSt) to 200 fluid (5000 cSt). Corresponding density data have been taken from the literature and the adiabatic compressibility determined. The measured adiabatic compressibility has been compared with two molecular models of wound velocity, the Schaaffs model and a development of the Urick equation. The Urick equation approach is based on a determination of the compressibility of the methylene or siloxane repeat units which make up the chains in these linear molecules. We show that the Urick equation approach accurately predicts sound velocity and compressibility for the higher members of each series, whilst the Schaaffs approach fails for the 1-alcohols. We suggest that this is because of the influence of the hydroxyl end group through hydrogen bonding with methylene groups within the chain. This interaction modifies the derived compressibility of the methylene groups, so reducing their compressibility relative to that of the n-alkanes. The technique described provides valuable new insights into end-group, intermolecular and intra-molecular interactions in liquid linear-chain molecules. From this detailed analysis of the mechanisms involved, a model is derived. This model can give very precise estimations of the composition of a pure liquid. In the case of mixtures of polymers, it is necessary to use the modified Urick equation and then, in addition, the concentration dependence of both the
Sound field separation with sound pressure and particle velocity measurements.
Fernandez-Grande, Efren; Jacobsen, Finn; Leclère, Quentin
2012-12-01
In conventional near-field acoustic holography (NAH) it is not possible to distinguish between sound from the two sides of the array, thus, it is a requirement that all the sources are confined to only one side and radiate into a free field. When this requirement cannot be fulfilled, sound field separation techniques make it possible to distinguish between outgoing and incoming waves from the two sides, and thus NAH can be applied. In this paper, a separation method based on the measurement of the particle velocity in two layers and another method based on the measurement of the pressure and the velocity in a single layer are proposed. The two methods use an equivalent source formulation with separate transfer matrices for the outgoing and incoming waves, so that the sound from the two sides of the array can be modeled independently. A weighting scheme is proposed to account for the distance between the equivalent sources and measurement surfaces and for the difference in magnitude between pressure and velocity. Experimental and numerical studies have been conducted to examine the methods. The double layer velocity method seems to be more robust to noise and flanking sound than the combined pressure-velocity method, although it requires an additional measurement surface. On the whole, the separation methods can be useful when the disturbance of the incoming field is significant. Otherwise the direct reconstruction is more accurate and straightforward.
Iron sound velocities in shock wave experiments
Holmes, N C; Nguyen, J H
1999-08-20
We have performed a series of sound velocity measurements in iron at earth's core pressures. Experiments were carried out at shock pressures as high as 400 GPa, with particular emphasis on the pressure range between 175 GPa and 275 GPa. The measured sound velocities of iron at elevated pressures exhibit a single discontinuity near 250 GPa, corresponding to the vanishing of shear strength as the iron melts. A second discontinuity reported by Brown and McQueen in their previous iron sound velocity studies was not observed in our study. Our results are consistent with their data otherwise. Experimental details and error propagation techniques essential to determining the melting point will also be discussed.
The molecular velocity of sound. [aqueous solutions
NASA Technical Reports Server (NTRS)
Auslaender, D.; Onitiu, L.
1974-01-01
The molecular velocity of sound was calculated according to Rao's formula and the temperature and concentration dependences of this value were studied in aqueous solutions of alkali and alkaline-earth halides. Study of relative association brought to light characteristic effects of ions. The variation of the relative association can be explained by a breaking of hydrogen bonds by ions and thermal agitation.
Sound Velocity Bound and Neutron Stars
Bedaque, Paulo; Steiner, Andrew W.
2015-01-21
A conjecture that the velocity of sound in any medium is smaller than the velocity of light in vacuum divided by sqrt(3). Simple arguments support this bound in nonrelativistic and/or weakly coupled theories. Moreover, the bound has been demonstrated in several classes of strongly coupled theories with gravity duals and is saturated only in conformal theories. Here, we point out that the existence of neutron stars with masses around two solar masses combined with the knowledge of the equation of state of hadronic matter at low densities is in strong tension with this bound.
Sound velocity estimation: A system theoretic approach
Candy, J.V.; Sullivan, E.J.
1993-07-30
A system-theoretic approach is proposed to investigate the feasibility of reconstructing a sound velocity profile (SVP) from acoustical hydrophone measurements. This problem is based on a state-space representation of the normal-mode propagation model. It is shown that this representation can be utilized to investigate the so-called observability of the SVP from noisy measurement data. A model-based processor is developed to extract this information and it is shown that even in cases where limited SVP information is available, the SVP can be estimated using this approach.
Adiabatic and entropy decomposition in P (ϕI, XI J) theories with multiple sound speeds
NASA Astrophysics Data System (ADS)
Longden, Chris
2017-01-01
We consider P (ϕI,XI J) theories of multifield inflation and ask the question of how to define the adiabatic and entropy perturbations, widely used in calculating the curvature and isocurvature power spectra, in this general context. It is found that when the field perturbations propagate with different speeds, these adiabatic and entropy modes are not generally the fundamental (most natural to canonically quantize) degrees of freedom that propagate with a single speed. The alternative fields which do propagate with a single speed are found to be a rotation in field space of the adiabatic and entropy perturbations. We show how this affects the form of the horizon-crossing power spectrum, when there is not a single "adiabatic sound speed" sourcing the curvature perturbation. Special cases of our results are discussed, including P (X ) theories where the adiabatic and entropy perturbations are fundamental. We finally look at physical motivations for considering multispeed models of inflation, particularly showing that disformal couplings can naturally lead to the kind of kinetic interactions which cause fields to have different sound speeds.
Velocity and attenuation of sound in arterial tissues
NASA Technical Reports Server (NTRS)
Rooney, J. A.; Gammell, P. M.; Hestenes, J. D.; Chin, H. P.; Blankenhorn, D. H.
1982-01-01
The velocity of sound in excised human and canine arterial tissues is measured in order to serve as a basis for the development and application of ultrasonic techniques for the diagnosis of atherosclerotic lesions. Measurements of sound velocity at different regions of 11 human and six canine aortas were made by a time delay spectrometer technique at frequencies from 2 to 10 MHz, and compared with ultrasonic attenuation parameters and the results of biochemical assays. Sound velocity is found to increase with increasing attenuation at all frequencies, and with increasing collagen content. A strong dependence of sound velocity on cholesterol content or low calcium contents is not observed, although velocities of up to 2000 m/sec are observed in highly organized calcified lesions. A decrease in velocity with decreasing temperature is also noted. It is thus concluded that it is principally the differences in tissue collagen levels that contribute to image formation according to sound velocity.
Accurate Sound Velocity Measurement in Ocean Near-Surface Layer
NASA Astrophysics Data System (ADS)
Lizarralde, D.; Xu, B. L.
2015-12-01
Accurate sound velocity measurement is essential in oceanography because sound is the only wave that can propagate in sea water. Due to its measuring difficulties, sound velocity is often not measured directly but instead calculated from water temperature, salinity, and depth, which are much easier to obtain. This research develops a new method to directly measure the sound velocity in the ocean's near-surface layer using multi-channel seismic (MCS) hydrophones. This system consists of a device to make a sound pulse and a long cable with hundreds of hydrophones to record the sound. The distance between the source and each receiver is the offset. The time it takes the pulse to arrive to each receiver is the travel time.The errors of measuring offset and travel time will affect the accuracy of sound velocity if we calculated with just one offset and one travel time. However, by analyzing the direct arrival signal from hundreds of receivers, the velocity can be determined as the slope of a straight line in the travel time-offset graph. The errors in distance and time measurement result in only an up or down shift of the line and do not affect the slope. This research uses MCS data of survey MGL1408 obtained from the Marine Geoscience Data System and processed with Seismic Unix. The sound velocity can be directly measured to an accuracy of less than 1m/s. The included graph shows the directly measured velocity verses the calculated velocity along 100km across the Mid-Atlantic continental margin. The directly measured velocity shows a good coherence to the velocity computed from temperature and salinity. In addition, the fine variations in the sound velocity can be observed, which is hardly seen from the calculated velocity. Using this methodology, both large area acquisition and fine resolution can be achieved. This directly measured sound velocity will be a new and powerful tool in oceanography.
The shock Hugoniot of 316 ss and sound velocity measurements
Hixson, R.S.; McQueen, R.G.; Fritz, J.N.
1993-01-01
Type 316 stainless steel has been characterized for its high-pressure, shock-wave response. Measurements have been made of shock-wave and particle velocity, and of sound velocity. Our preliminary results for shock and particle velocity have been combined with previously unpublished results, and an overall fit made. Sound velocity results show a discontinuity that is attributed to shock-induced melting.
The shock Hugoniot of 316 ss and sound velocity measurements
Hixson, R.S.; McQueen, R.G.; Fritz, J.N.
1993-07-01
Type 316 stainless steel has been characterized for its high-pressure, shock-wave response. Measurements have been made of shock-wave and particle velocity, and of sound velocity. Our preliminary results for shock and particle velocity have been combined with previously unpublished results, and an overall fit made. Sound velocity results show a discontinuity that is attributed to shock-induced melting.
Molybdenum Sound Velocity and Shear Strength Softening
NASA Astrophysics Data System (ADS)
Nguyen, Jeffrey; Akin, Minta; Chau, Ricky; Fratandouno, Dayne; Ambrose, Pat; Fat'yanov, Oleg; Asimow, Paul; Holmes, Neil
2013-06-01
We recently carried out a series of light-gas gun experiments to measure molybdenum acoustic sound speed up to 5 Mbars on the Hugoniot. Our measured sound speeds increase linearly with pressure up to 2.6 Mbars and taper off near the melting pressure. The gradual leveling off of sound speed suggests a possible loss of shear strength near the melt. A linear extrapolation of our data to zero pressure is in good agreement with the sound speed measured at ambient condition. The results indicate that molybdenum remains in the bcc phase on the Hugoniot up to the melting pressure. There is no bcc solid phase transition on the Hugoniot as previously reported. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Kozlov, E. A.; Tarzhanov, V. I.; Pankratov, D. G.; Yakunin, A. K.; Yelkin, V. M.; Mikhailov, V. N.
2006-08-03
Registration results of longitudinal CL({sigma}XX) and volume CB({sigma}XX) sound velocities in shock-compressed aluminum alloy are presented. Experimental data were obtained in wide range of longitudinal stress, including the stress, corresponding to solid-liquid shock-induced transformation. By using experimentally measured values of sound velocities, the changes of Poisson ratio and shear modulus were calculated along the shock adiabat. These data are needed for calibration of resent elastic-viscous-plastic models.
NASA Astrophysics Data System (ADS)
Smith, David Eugene
Little basic research has been reported on the physical structure of aqueous solutions of saccharides. Sound velocimeters can be used to study physical structure of solutions, non-destructively. The La Place relationship was used to calculate adiabatic compressibility values for solutions from experimentally determined values for sound velocity and density. Using a sound velocimeter, aqueous solutions of twelve alditols and saccharides were studied at various concentrations and temperatures. Data indicated that over most of the temperature range employed (20 to 70 C) adiabatic compressibility of the solutions was the dominant factor in defining sound velocity through and structural rigidity of solution. As concentration of solute increased, more rigid structures were formed in solution, which caused sound velocity values to increase with increasing concentrations of solute; maximum sound velocity values were obtained at progressively lower temperatures. Analysis of data for sound velocity, density and adiabatic compressibility of various solutions provided partial insight into effects of each solute molecule on structure of solutions. A furanose form in a monosaccharide contributed to a more rigid structure than did a pyranose ring when below 30C. At higher temperatures the pyranose ring provided more rigidity than did the furanose ring. Hydroxyl groups in the equatorial position generally contributed more to rigidity of structure than did OH groups in axial positions. Disaccharides contributed differences from the inherent monosaccharides. A (beta) glycosidic linkage provided more structural rigidity of solution than did a linkage. Among the alditols, mannitol and sorbitol contributed very similar characteristics to solutions. Xylitol, in solution provided less rigidity, density and sound velocity than did mannitol-sorbitol in proportion to the lower molecular weight or xylitol. From the data for velocity of sound through single sugar solutions values for
Sound Velocity and Elasticity of Tetragonal Lysozyme Crystals by Brillouin Spectroscopy
Speziale, S.; Jiang, F.; Caylor, C. L.; Kriminski, S.; Zha, C.-S.; Thorne, R. E.; Duffy, T. S.
2003-01-01
Quasilongitudinal sound velocities and the second-order elastic moduli of tetragonal hen egg-white lysozyme crystals were determined as a function of relative humidity (RH) by Brillouin scattering. In hydrated crystals the measured sound velocities in the [110] plane vary between 2.12 ± 0.03 km/s along the [001] direction and 2.31 ± 0.08 km/s along the [110] direction. Dehydration from 98% to 67% RH increases the sound velocities and decreases the velocity anisotropy in (110) from 8.2% to 2.0%. A discontinuity in velocity and an inversion of the anisotropy is observed with increasing dehydration providing support for the existence of a structural transition below 88% RH. Brillouin linewidths can be described by a mechanical model in which the phonon is coupled to a relaxation mode of hydration water with a single relaxation time of 55 ± 5 ps. At equilibrium hydration (98% RH) the longitudinal moduli C11 + C12 + 2C66 = 12.81 ± 0.08 GPa, C11 = 5.49 ± 0.03 GPa, and C33 = 5.48 ± 0.05 GPa were directly determined. Inversion of the measured sound velocities in the [110] plane constrains the combination C44 + ½C13 to 2.99 ± 0.05 GPa. Further constraints on the elastic tensor are obtained by combining the Brillouin quasilongitudinal results with axial compressibilities determined from high-pressure x-ray diffraction. We constrain the adiabatic bulk modulus to the range 2.7–5.3 GPa. PMID:14581220
The Adiabatic Demagnetization Refrigerator for the Micro-X Sounding Rocket Telescope
NASA Astrophysics Data System (ADS)
Wikus, P.; Adams, J. S.; Bagdasarova, Y.; Bandler, S. R.; Doriese, W. B.; Eckart, M. E.; Figueroa-Feliciano, E.; Kelley, R. L.; Kilbourne, C. A.; Leman, S. W.; McCammon, D.; Porter, F. S.; Rutherford, J. M.; Trowbridge, S. N.
2010-04-01
The Micro-X Imaging X-ray Spectrometer is a sounding rocket payload slated for launch in 2011. An array of Transition Edge Sensors, which is operated at a bath temperature of 50 mK, will be used to obtain a high resolution spectrum of the Puppis-A supernova remnant. An Adiabatic Demagnetization Refrigerator (ADR) with a 75 gram Ferric Ammonium Alum (FAA) salt pill in the bore of a 4 T superconducting magnet provides a stable heat sink for the detector array only a few seconds after burnout of the rocket motors. This requires a cold stage design with very short thermal time constants. A suspension made from Kevlar strings holds the 255 gram cold stage in place. It is capable of withstanding loads in excess of 200 g. Stable operation of the TES array in proximity to the ADR magnet is ensured by a three-stage magnetic shielding system which consists of a superconducting can, a high-permeability shield and a bucking coil. The development and testing of the Micro-X payload is well underway.
THE ADIABATIC DEMAGNETIZATION REFRIGERATOR FOR THE MICRO-X SOUNDING ROCKET TELESCOPE
Wikus, P.; Bagdasarova, Y.; Figueroa-Feliciano, E.; Leman, S. W.; Rutherford, J. M.; Trowbridge, S. N.; Adams, J. S.; Bandler, S. R.; Eckart, M. E.; Kelley, R. L.; Kilbourne, C. A.; Porter, F. S.; Doriese, W. B.; McCammon, D.
2010-04-09
The Micro-X Imaging X-ray Spectrometer is a sounding rocket payload slated for launch in 2011. An array of Transition Edge Sensors, which is operated at a bath temperature of 50 mK, will be used to obtain a high resolution spectrum of the Puppis-A supernova remnant. An Adiabatic Demagnetization Refrigerator (ADR) with a 75 gram Ferric Ammonium Alum (FAA) salt pill in the bore of a 4 T superconducting magnet provides a stable heat sink for the detector array only a few seconds after burnout of the rocket motors. This requires a cold stage design with very short thermal time constants. A suspension made from Kevlar strings holds the 255 gram cold stage in place. It is capable of withstanding loads in excess of 200 g. Stable operation of the TES array in proximity to the ADR magnet is ensured by a three-stage magnetic shielding system which consists of a superconducting can, a high-permeability shield and a bucking coil. The development and testing of the Micro-X payload is well underway.
Anomalous sound velocity in multiferroic BiFeO3
NASA Astrophysics Data System (ADS)
Cao, Xian-Sheng; Ji, Gao-Feng; Jiang, Xing-Fang
2016-11-01
The sound velocity in multiferroic BiFeO3 (BFO) is studied with using Green's function technology on the basis of the magnetoelectric coupling, the spin-phonon interaction and the anharmonic phonon-phonon interaction. The Heisenberg-like model is employed to describe the magnetic subsystem, and the transverse Ising model is used to explain the ferroelectric subsystem. The reduced velocity is obtained in the limit of zero wave vectors. It is shown that the reduced velocity of sound in BiFeO3 exhibits a kink at the magnetic phase transition temperature TN. This anomaly in reduced velocity can be explained as an influence of vanishing magnetic ordering above TN and the ferroelectric subsystem can not be influenced by the magnetic subsystem above TN due to TN≪TC in the BFO. It is shown that the influence of the RM is only below TN in the phase where ferroelectric and magnetic properties exist together, whereas the RE influences the properties of the reduced velocity in the whole temperature region (T
Thermodynamic properties of nitrogen gas from sound velocity measurements
NASA Technical Reports Server (NTRS)
Younglove, B. A.
1979-01-01
Thermodynamic properties of nitrogen gas have been calculated from 80 K to 350 K and at pressures to 10 bar from sound velocity measurements and existing P-V-T data using multiproperty fitting techniques. These new data are intended to improve existing predictive capability of the equation of state in the low density region needed for use with the NASA-Langley National Transonics Facility.
Sound velocity of drilling mud saturated with reservoir gas
Carcione, J.M.; Poletto, F.
2000-04-01
Knowledge of the in-situ sound velocity of drilling mud can be used in mud-pulse acoustic telemetry for evaluating the presence and amount of gas invasion in the drilling mud. The authors propose a model for calculating the in-situ density and sound velocity of water-based and oil-based drilling muds containing formation gas. Drilling muds are modeled as a suspension of clay particles and high-gravity solids in water or oil, with the acoustic properties of these fluids depending on pressure and temperature. Since mud at different depths experiences different pressures and temperatures, downhold mud weights can be significantly different from those measured at the surface. Taking this fact into consideration, the authors assume constant clay composition and obtained the fraction of high-gravity solids to balance the formation pressure corresponding to a given drilling plan. This gives the in-situ density of the drilling mud, which together with the bulk moduli of the single constituents allow one to compute the second velocity using Reuss's model. In the case of oil-based muds, they take into account the gas solubility in oil. When gas goes into solution, the mud is compassed of solid particles, live oil and, eventually, free gas. A phenomenological model based on a continuous spectrum of relaxation mechanisms is used to describe attenuation due to mud viscosity. The calculations for water-based and oil-based muds showed that the sound velocity is strongly dependent on gas saturation, fluid composition, and drilling depth.
Discrimination of sound source velocity in human listeners
NASA Astrophysics Data System (ADS)
Carlile, Simon; Best, Virginia
2002-02-01
The ability of six human subjects to discriminate the velocity of moving sound sources was examined using broadband stimuli presented in virtual auditory space. Subjects were presented with two successive stimuli moving in the frontal horizontal plane level with the ears, and were required to judge which moved the fastest. Discrimination thresholds were calculated for reference velocities of 15, 30, and 60 degrees/s under three stimulus conditions. In one condition, stimuli were centered on 0° azimuth and their duration varied randomly to prevent subjects from using displacement as an indicator of velocity. Performance varied between subjects giving median thresholds of 5.5, 9.1, and 14.8 degrees/s for the three reference velocities, respectively. In a second condition, pairs of stimuli were presented for a constant duration and subjects would have been able to use displacement to assist their judgment as faster stimuli traveled further. It was found that thresholds decreased significantly for all velocities (3.8, 7.1, and 9.8 degrees/s), suggesting that the subjects were using the additional displacement cue. The third condition differed from the second in that the stimuli were ``anchored'' on the same starting location rather than centered on the midline, thus doubling the spatial offset between stimulus endpoints. Subjects showed the lowest thresholds in this condition (2.9, 4.0, and 7.0 degrees/s). The results suggested that the auditory system is sensitive to velocity per se, but velocity comparisons are greatly aided if displacement cues are present.
NASA Astrophysics Data System (ADS)
Irifune, T.; Higo, Y.; Kono, Y.; Inoue, T.; Funakoshi, K.
2007-12-01
We have developed techniques to precisely measure the sound velocities of high-pressure phases at pressures to 22 GPa and temperatures to 1800K using a combination of synchrotron in situ X-ray and ultrasonic measurements with a Kawai-type multianvil apparatus. Using these techniques, we measured the sound velocities of ringwoodite and majorite in a pyrolite composition , as well as those of MORB in the garnetite facies (majorite + minor stishovite). We found quite strong non-linear decreases of Vp and Vs with temperature, particularly for Vs in majorite, under these P, T conditions of the mantle transition region (MTR). Our results suggest that pyrolite yields seismic velocities consistent with typical seismological models for the MTR, except for the bottom part of this region, whereas piclogite or basalt compositions may lead to velocities substantially lower than those seismologically derived. In contrast, harzburgite would better fit to the seismological models in the lower half of the mantle transition region, provided that the geotherm in this region is of adiabatic, which may be due to accumulation of main bodies of stagnant slabs (depleted peridotite or harzburgite) near the 660 km discontinuity.
Sound velocities and elastic constants of iron-bearing hydrous ringwoodite
NASA Astrophysics Data System (ADS)
Jacobsen, Steven D.; Smyth, Joseph R.; Spetzler, Hartmut; Holl, Christopher M.; Frost, Daniel J.
2004-06-01
The sound velocities and single-crystal elastic constants of Fo 89 hydrous ringwoodite (γ-Mg 1.7Fe 0.22H 0.16SiO 4) containing ˜10,000 ppm by weight (1 wt.%) H 2O have been determined from seven separate pure-mode travel-time measurements using gigahertz ultrasonic interferometry. The experiments feature a new Yttrium-Aluminum-Garnet (YAG) P-to-S conversion shear buffer rod (BR), capable of producing pure ultrasonic shear waves with known polarization in the region of 0.5-2.0 GHz. To our knowledge they are the first such single-crystal ultrasonic measurements on a high-pressure phase recovered from the multi-anvil press. The cubic single-crystal elastic constants of hydrous Fo 89 ringwoodite at ambient conditions are (in GPa): c11=298±13, c44=112±6, and c12=115±6. Hydration of Fo ˜90 ringwoodite to 1 wt.% H 2O reduces the adiabatic bulk ( K0S=176±7 GPa) and shear ( G=103±5 GPa) moduli by about 6 and 13%, roughly equivalent to raising the temperature at room pressure by 600 and 1000 °C, respectively. Assuming a linear trend with hydration, we calculate that P- and S-wave velocities are reduced by about 40 m/s for every 1000 ppm weight (0.1 wt.%) H 2O added to Fo ˜90 ringwoodite. P- and S-wave velocities of the lower transition zone in PREM are consistent with a hydrated ringwoodite-rich composition.
Sound velocity determination of PbTe under pressure
NASA Astrophysics Data System (ADS)
Jacobsen, Matthew; Liu, Wei; Li, Baosheng
2013-06-01
Recent investigations of PbTe have revealed interesting high pressure transitions resulting in improved thermoelectric performance. High pressure sound velocities of PbTe have been measured to 14 GPa using an ultrasonic interferometric method. Elastic moduli and their pressure derivatives for phases in this range have been obtained using a finite strain approach. From this, an estimate of the acoustic phonon contribution to the thermal conductivity is made. By combining this with previous determinations of the thermal conductivity due to electrons, a significantly lower value than the previously determined total thermal conductivity is found. This is interpreted as evidence for coupling between the low-lying transverse optic (TO) and longitudinal acoustic (LA) modes allowing transfer of thermal energy between them. The application of pressure causes energy transference between the optical modes and electron population, which is likely the cause of the increased thermoelectric efficiency in the intermediate Pbnm state. This research is supported by the DoE/NNSA under contract number DE-FG5209NA29458 to BL. WL is also supported by the NSF under contract number EAR-1045630.
NASA Astrophysics Data System (ADS)
Kühnicke, Elfgard; Wolf, Mario; Kümmritz, Sebastian
2017-02-01
This paper describes a non-invasive, nondestructive method for the simultaneous determination of sound velocity and thickness of the different layers of a layered structure by means of ultrasound. It will be demonstrated how further information about the reflected sound field, in addition to the time of flight, is acquired by using annular arrays. Because of this supplementary information, reflectors or other probes at known distances are not necessary and the specimen does not have to be placed in a medium with known sound velocity. Two different evaluation methods combined with a geometric model are explained. To improve the accuracy, measured signals are also evaluated by a wave propagation model.
Sound velocity of tantalum under shock compression in the 18–142 GPa range
Xi, Feng Jin, Ke; Cai, Lingcang Geng, Huayun; Tan, Ye; Li, Jun
2015-05-14
Dynamic compression experiments of tantalum (Ta) within a shock pressure range from 18–142 GPa were conducted driven by explosive, a two-stage light gas gun, and a powder gun, respectively. The time-resolved Ta/LiF (lithium fluoride) interface velocity profiles were recorded with a displacement interferometer system for any reflector. Sound velocities of Ta were obtained from the peak state time duration measurements with the step-sample technique and the direct-reverse impact technique. The uncertainty of measured sound velocities were analyzed carefully, which suggests that the symmetrical impact method with step-samples is more accurate for sound velocity measurement, and the most important parameter in this type experiment is the accurate sample/window particle velocity profile, especially the accurate peak state time duration. From these carefully analyzed sound velocity data, no evidence of a phase transition was found up to the shock melting pressure of Ta.
Li, Baosheng; Liebermann, Robert C
2007-05-29
The adiabatic bulk (K(S)) and shear (G) moduli of mantle materials at high pressure and temperature can be obtained directly by measuring compressional and shear wave velocities in the laboratory with experimental techniques based on physical acoustics. We present the application of the current state-of-the-art experimental techniques by using ultrasonic interferometry in conjunction with synchrotron x radiation to study the elasticity of olivine and pyroxenes and their high-pressure phases. By using these updated thermoelasticity data for these phases, velocity and density profiles for a pyrolite model are constructed and compared with radial seismic models. We conclude that pyrolite provides an adequate explanation of the major seismic discontinuities at 410- and 660-km depths, the gradient in the transition zone, as well as the velocities in the lower mantle, if the uncertainties in the modeling and the variations in different seismic models are considered. The characteristics of the seismic scaling factors in response to thermal anomalies suggest that anticorrelations between bulk sound and shear wave velocities, as well as the large positive density anomalies observed in the lower mantle, cannot be explained fully without invoking chemical variations.
Li,B.; Liebermann, R.
2007-01-01
The adiabatic bulk (K S) and shear (G) moduli of mantle materials at high pressure and temperature can be obtained directly by measuring compressional and shear wave velocities in the laboratory with experimental techniques based on physical acoustics. We present the application of the current state-of-the-art experimental techniques by using ultrasonic interferometry in conjunction with synchrotron x radiation to study the elasticity of olivine and pyroxenes and their high-pressure phases. By using these updated thermoelasticity data for these phases, velocity and density profiles for a pyrolite model are constructed and compared with radial seismic models. We conclude that pyrolite provides an adequate explanation of the major seismic discontinuities at 410- and 660-km depths, the gradient in the transition zone, as well as the velocities in the lower mantle, if the uncertainties in the modeling and the variations in different seismic models are considered. The characteristics of the seismic scaling factors in response to thermal anomalies suggest that anticorrelations between bulk sound and shear wave velocities, as well as the large positive density anomalies observed in the lower mantle, cannot be explained fully without invoking chemical variations.
NASA Astrophysics Data System (ADS)
Ohtani, E.; Kamada, S.; Sakai, T.; Terasaki, H.; Shibazaki, Y.; Sakamaki, T.; Takahashi, S.; Sakairi, T.; Fukui, H.; Baron, A. Q.
2012-12-01
The sound velocity is one of the most important physical properties which can be assessed by seismology. In spite of its importance, the technical difficulty provides limitation of the measurements under the core conditions. Here we show the results of measurements of the sound velocity of hcp-iron, Fe3S, and FeH by the inelastic X-ray scattering (IXS) method using DAC at high pressure and temperature. Inelastic X-ray scattering spectra were taken at BL35XU, Spring-8. We made the measurements of hcp-iron at pressures up to 180 GPa at room temperature, which is the highest pressure for the IXS measurement. Sound velocity measurements at high pressure and temperature were made up to 91 GPa at 700 K, and to 62 GPa and 1000 K using the external heating diamond anvil cell. The present results revealed that there is almost no temperature effect on the sound velocity of hcp-Fe at least up to 1000 K. We also measured the sound velocity and density of Fe3S up to 85 GPa at room temperature, and clarified the effect of sulfur and hydrogen on the sound velocity of iron at high pressure. Phase relations of the Fe-S (Kamada et al., 2010; 2012) and Fe-S-O systems (Terasaki et al., 2011) were studied up to the core pressures based on the laser heated diamond anvil cell combined with the in situ synchrotron X-ray diffraction at SPring-8. Fe3S dissolves first at the solidus before melting of FeO and metallic iron alloy at the liquidus of the systems up to 180 GPa. The maximum solubility of sulfur in hcp-iron approaches to about 7.5 at % at 86 GPa and 8 at % at 123 GPa, and it does not increase so much at higher pressures. The temperature at ICB based on the extrapolation of the liquidus and solidus temperatures of the outer core composition in the Fe-S-O is about 4360-5630 K assuming that the outer core composition is Fe75O5S20 in the atomic ratio. The temperature at the core-mantle boundary will be 3340-4300 K by the adiabatic decompression from the temperature at the inner core
Lugli, Marco; Fine, Michael L
2007-11-01
The most sensitive hearing and peak frequencies of courtship calls of the stream goby, Padogobius martensii, fall within a quiet window at around 100 Hz in the ambient noise spectrum. Acoustic pressure was previously measured although Padogobius likely responds to particle motion. In this study a combination pressure (p) and particle velocity (u) detector was utilized to describe ambient noise of the habitat, the characteristics of the goby's sounds and their attenuation with distance. The ambient noise (AN) spectrum is generally similar for p and u (including the quiet window at noisy locations), although the energy distribution of u spectrum is shifted up by 50-100 Hz. The energy distribution of the goby's sounds is similar for p and u spectra of the Tonal sound, whereas the pulse-train sound exhibits larger p-u differences. Transmission loss was high for sound p and u: energy decays 6-10 dB10 cm, and sound pu ratio does not change with distance from the source in the nearfield. The measurement of particle velocity of stream AN and P. martensii sounds indicates that this species is well adapted to communicate acoustically in a complex noisy shallow-water environment.
Temperature Dependence of Sound Velocity in High-Strength Fiber-Reinforced Plastics
NASA Astrophysics Data System (ADS)
Nomura, Ryuji; Yoneyama, Keiichi; Ogasawara, Futoshi; Ueno, Masashi; Okuda, Yuichi; Yamanaka, Atsuhiko
2003-08-01
Longitudinal sound velocity in unidirectional hybrid composites or high-strength fiber-reinforced plastics (FRPs) was measured along the fiber axis over a wide temperature range (from 77 K to 420 K). We investigated two kinds of high-strength crystalline polymer fibers, polyethylene (Dyneema) and polybenzobisoxazole (Zylon), which are known to have negative thermal expansion coefficients and high thermal conductivities along the fiber axis. Both FRPs had very high sound velocities of about 9000 m/s at low temperatures and their temperature dependences were very strong. Sound velocity monotonically decreased with increasing temperature. The temperature dependence of sound velocity was much stronger in Dyneema-FRP than in Zylon-FRP.
Resonant transmission and velocity renormalization of third sound in one-dimensional random lattices
Kono, K.; Nakada, S. )
1992-08-24
Localization properties of third sound were studied experimentally in one-dimensional random lattices. Transmission spectra were measured and compared with those in periodic, Fibonacci, and Thue-Morse lattices. Not only the resonant transmission but also the phase-velocity renormalization of third sound was observed in the random lattices.
NASA Technical Reports Server (NTRS)
Nayfeh, A. H.; Sun, J.
1974-01-01
An investigation is described of the effect of transverse mean-velocity and temperature gradients on sound attenuation in acoustically treated two-dimensional ducts. The results show that cooling the duct walls leads to channeling the sound toward the walls for both downstream and upstream propagation. The effect of mean-temperature gradients on the attenuation rates of the lowest three modes can be as important as the effect of mean-velocity gradients.
Measurement of the sound velocity in fluids using the echo signals from scattering particles.
Lenz, Michael; Bock, Martin; Kühnicke, Elfgard; Pal, Josef; Cramer, Andreas
2012-01-01
With conventional methods the sound velocity c in fluids can be determined using the back wall echo. This paper proposes a novel technique, in which the signals reflected by scattering particles suspended in a fluid are analysed instead. The basic idea is that the particles generate the strongest echo signal when being located in the sound field maximum. Therefore the position of the echo signal maximum is a measure for the propagation time to the sound field maximum. Provided that calibration data or sound field simulations for the ultrasonic transducer are available, this propagation time suffices to determine both sound velocity and the location of the sound field maximum. The feasibility of the new approach is demonstrated by different kinds of experiments: (i) Measurements of the sound velocity c in four fluids covering the wide range between 1116 and 2740m/s. The results show good agreement with values published elsewhere. (ii) Using the dependence of the sound velocity on temperature, it is possible to vary c over the comparatively small range between 1431 and 1555m/s with increments of less than 10m/s. The measured statistical variation of 1.4m/s corresponds to a relative uncertainty not worse than 0.1%. (iii) The focus position, i.e. the distance of the maximum of the sound field from the transducer, was varied by time-shifted superposition of the receive signals belonging to the different elements of an annular array. The results indicate that the novel method is even capable of measuring profiles of the sound velocity along the ultrasonic beam non-invasively.
NASA Astrophysics Data System (ADS)
Motegi, Takahiro; Mizutani, Koichi; Wakatsuki, Naoto
2013-07-01
In this paper, an acoustic technique for air temperature and humidity measurement in moist air is described. The previous ultrasonic probe can enable the estimation of temperature from sound velocity in dry air by making use of the relationship between sound velocity and temperature. However, temperature measurement using the previous ultrasonic probe is not suitable in moist air because sound velocity also depends on humidity, and the temperature estimated from the sound velocity measured in moist air must be adjusted. Moreover, a method of humidity measurement by using only an ultrasonic probe has not been established. Thus, we focus on sound attenuation, which depends on temperature and humidity. Our proposed technique utilizes two parameters, sound velocity and attenuation, and can measure both temperature and humidity simultaneously. The acoustic technique for temperature and humidity measurement has the advantages that instantaneous temperature and humidity can be measured, and the measurement is not affected by thermal radiation because air itself is used as a sensing element. As an experiment, temperature and humidity are measured in a chamber, and compared with the reference values. The experimental results indicate the achievement of a practical temperature measurement accuracy of within +/-0.5 K in moist air, of which the temperature is 293-308 K and relative humidity (RH) is 50-90% RH, and the simultaneous measurement of temperature and humidity.
[Sound and velocity DPOAEs : Technology, methodology and perspectives].
Dalhoff, E; Vetesník, A; Turcanu, D; Gummer, A W
2010-06-01
Recent publications show that DPOAE measurements can generate a more accurate diagnosis, if (1) their fine structure is suppressed, and (2) if the calibration of the sound field is improved. Reduction of the fine structure is particularly important in the frequency range below 4 kHz in subjects with intact cochlear amplifier and can reduce the standard deviation of threshold estimations based on DPOAE-input/output functions from 11 dB to 6 dB. Improving the sound-field calibration has most impact in the frequency range above 4 kHz. Threshold estimations based on laserinterferometrically measured DPOAE input-output functions where the sound field was calibrated close to the tympanic membrane have been shown to reduce the standard deviation down to 8.6 dB in humans and 6.5 dB in guinea pigs. Compared with conventional DPOAE measures, such as amplitude or signal-to-noise ratio, threshold estimation based on DPOAE-I/O functions has the advantage that its slope provides additional information about the middle-ear; however, its specificity is limited. In the future, combined methods such as acoustic reflectance or laser vibrometry on the umbo promise a reliable assessment of the middle-ear contribution to DPOAE.
Equation of State and Sound Velocities from Isotropic Continuum Mechanics.
1986-10-01
of state and the shear and longitudinal velocity to fifth order elastic constants. The resulting expressions are implicit in terms of the pressure...The methods of finite elasticity in continuum mechanics of homogeneous isotropic materials are used to obtain the pressure dependence of the equation
Velocity controlled sound field reproduction by non-uniformly spaced loudspeakers
NASA Astrophysics Data System (ADS)
Shin, Mincheol; Nelson, Philip A.; Fazi, Filippo M.; Seo, Jeongil
2016-05-01
One approach to the reproduction of a sound field is to ensure the reproduction of the acoustic pressure on the surface bounding the volume within which reproduction is sought. However, this approach suffers from technical limitations when the loudspeakers used for the reproduction of the surface acoustic pressures are unevenly spaced. It is shown in this paper that sound field reproduction with a spatially non-uniform loudspeaker arrangement can be considerably improved by changing the physical quantity to be controlled on the bounding surface from pressure to particle velocity. One of the main advantages of the velocity control method is the simplicity with which the inverse problem can be regularized, irrespective of the direction of arrival of the sound to be reproduced. In addition, the velocity controlled sound field shows better reproduction of the time averaged intensity flow in the reproduction region which in turn appears to be closely linked with better human perception of sound localization. Furthermore, the proposed method results in smoother "panning functions" that describe the variation of the source outputs as a function of the angle of incidence of the sound to be reproduced. The performance of the velocity matching method has been evaluated by comparison to the conventional pressure matching method and through simulations with several non-uniform loudspeaker layouts. The simulated results were also verified with experiments and subjective tests.
NASA Astrophysics Data System (ADS)
Sanemasa, M.; Saiki, K.; Kaneko, K.; Ohba, T.; Kusakabe, M.; Tanyileke, G.; Hell, J.
2012-12-01
1. Introduction Limnic eruptions at Lakes Monoun and Nyos in Cameroon, which are sudden degassing of magmatic CO2 dissolved in the lake water, occurred in 1984 and 1986, respectively. The disasters killed about 1800 people around the lakes. Because of ongoing CO2 accumulation in the bottom water of the lakes, tragedy of limnic eruptions will possibly occur again. To prevent from further disasters, artificial degassing of CO2 from the lake waters has been undergoing. Additionally, CO2 monitoring of the lake waters is needed. Nevertheless, CO2 measurement is done only once or twice a year because current methods of CO2 measurement, which require chemical analysis of water samples, are not suitable for frequent measurement. In engineering field, on the other hand, a method to measure salt concentration using sound velocity has been proposed (Kleis and Sanchez, 1990). This method allows us to evaluate solute concentration fast. We applied the method to dissolved CO2 and examined the correlation between sound velocity and CO2 concentration in laboratory experiment. Furthermore, using the obtained correlation, we tried to estimate the CO2 concentration of waters in the Cameroonian lakes. 2. Laboratory experiment We examined the correlation between sound velocity and CO2 concentration. A profiler (Minos X, made by AML oceanography) and pure water were packed in cylindrical stainless vessel and high-pressure CO2 gas was injected to produce carbonated water. The profiler recorded temperature, pressure and sound velocity. Change of sound velocity was defined as difference of sound velocity between carbonated water and pure water under the same temperature and pressure conditions. CO2 concentration was calculated by Henry's law. The result indicated that the change of sound velocity [m s-1] is proportional to CO2 concentration [mmol kg-1], and the coefficient is 0.021 [m kg s-1 mmol-1]. 3. Field application Depth profiles of sound velocity, pressure, and temperature of Lakes
Sound-velocity measurements for HFC-134a and HFC-152a with a spherical resonator
NASA Astrophysics Data System (ADS)
Hozumi, T.; Koga, T.; Sato, H.; Watanabe, K.
1993-07-01
A spherical acoustic resonator was developed for measuring sound velocities in the gaseous phase and ideal-gas specific heats for new refrigerants. The radius of the spherical resonator, being about 5 cm, was determined by measuring sound velocities in gaseous argon at temperatures from 273 to 348 K and pressures up to 240 kPa. The measurements of 23 sound velocities in gaseous HFC-134a (1,1,1,2-tetrafluoroethane) at temperatures of 273 and 298 K and pressures from 10 to 250 kPa agree well with the measurements of Goodwin and Moldover. In addition, 92 sound velocities in gaseous HFC-152a (1,1-difluoroethane) with an accuracy of ±0.01% were measured at temperatures from 273 to 348 K and pressures up to 250 kPa. The ideal-gas specific heats as well as the second acoustic virial coefficients have been obtained for both these important alternative refrigerants. The second virial coefficients for HFC-152a derived from the present sound velocity measurements agree extremely well with the reported second virial coefficient values obtained with a Burnett apparatus.
Cutoff frequency of sound velocities for a multi-slab Bose-Einstein condensate
NASA Astrophysics Data System (ADS)
Rodríguez, O. A.; Solís, M. A.
2015-03-01
An inhomogeneous multi-slab 3D Bose gas is produced by applying to the gas a Kronig-Penney potential in one direction, while the bosons are free to move in the other two directions. The variable density produces a dispersive effect over the sound waves, making the phase and group sound velocities frequency dependent. Below the critical temperature the dispersion relation between wavenumber and frequency ω (k) is determined by a constant factor called the curvature of the density, within the Klein-Gordon equation which describes the sound wave propagation in the condensate. Since the curvature of the density profiles between and inside the barriers are completely different, the sound velocities are distinct too. More importantly, in the region occupied by the slabs waves propagate only if their frequencies are greater than a cutoff frequency, otherwise evanescent waves arise. We show the density profile, the phase and group sound velocities and we give the curvature dependent cutoff frequency as obtained from the group velocity equation for the region occupied by the barriers. For high frequencies both phase and group velocities approach to that of a homogeneous gas at the same temperature. We acknowledge partial support from PAPIIT IN111613.
Second sound shock waves and critical velocities in liquid helium 2. Ph.D. Thesis
NASA Technical Reports Server (NTRS)
Turner, T. N.
1979-01-01
Large amplitude second-sound shock waves were generated and the experimental results compared to the theory of nonlinear second-sound. The structure and thickness of second-sound shock fronts are calculated and compared to experimental data. Theoretically it is shown that at T = 1.88 K, where the nonlinear wave steepening vanishes, the thickness of a very weak shock must diverge. In a region near this temperature, a finite-amplitude shock pulse evolves into an unusual double-shock configuration consisting of a front steepened, temperature raising shock followed by a temperature lowering shock. Double-shocks are experimentally verified. It is experimentally shown that very large second-sound shock waves initiate a breakdown in the superfluidity of helium 2, which is dramatically displayed as a limit to the maximum attainable shock strength. The value of the maximum shock-induced relative velocity represents a significant lower bound to the intrinsic critical velocity of helium 2.
A Method for Streamlining and Assessing Sound Velocity Profiles Based on Improved D-P Algorithm
NASA Astrophysics Data System (ADS)
Zhao, D.; WU, Z. Y.; Zhou, J.
2015-12-01
A multi-beam system transmits sound waves and receives the round-trip time of their reflection or scattering, and thus it is possible to determine the depth and coordinates of the detected targets using the sound velocity profile (SVP) based on Snell's Law. The SVP is determined by a device. Because of the high sampling rate of the modern device, the operational time of ray tracing and beam footprint reduction will increase, lowering the overall efficiency. To promote the timeliness of multi-beam surveys and data processing, redundant points in the original SVP must be screened out and at the same time, errors following the streamlining of the SVP must be evaluated and controlled. We presents a new streamlining and evaluation method based on the Maximum Offset of sound Velocity (MOV) algorithm. Based on measured SVP data, this method selects sound velocity data points by calculating the maximum distance to the sound-velocity-dimension based on an improved Douglas-Peucker Algorithm to streamline the SVP (Fig. 1). To evaluate whether the streamlined SVP meets the desired accuracy requirements, this method is divided into two parts: SVP streamlining, and an accuracy analysis of the multi-beam sounding data processing using the streamlined SVP. Therefore, the method is divided into two modules: the streamlining module and the evaluation module (Fig. 2). The streamlining module is used for streamlining the SVP. Its core is the MOV algorithm.To assess the accuracy of the streamlined SVP, we uses ray tracing and the percentage error analysis method to evaluate the accuracy of the sounding data both before and after streamlining the SVP (Fig. 3). By automatically optimizing the threshold, the reduction rate of sound velocity profile data can reach over 90% and the standard deviation percentage error of sounding data can be controlled to within 0.1% (Fig. 4). The optimized sound velocity profile data improved the operational efficiency of the multi-beam survey and data post
Sound velocity of high-strength polymer with negative thermal expansion coefficient
NASA Astrophysics Data System (ADS)
Nomura, R.; Ueno, M.; Okuda, Y.; Burmistrov, S.; Yamanaka, A.
2003-05-01
Sound velocities of fiber reinforced plastics (FRPs) were measured along the fiber axis at temperatures between 360 and 77 K. We used two kinds of the high-strength crystalline polymer fibers, polyethylene (Dyneema) and polybenzobisoxazole (Zylon), which have negative thermal expansion coefficients. They also have high thermal conductivities and high resistances for flash over voltage, and are expected as new materials for coil bobbins or spacers at cryogenic temperatures. They have very large sound velocities of about 9000 (m/s) at 77 K, which are 4.5 times larger than that of the ordinary polyethylene fiber.
Measurement of sound velocities of laser-shocked iron at pressures up to 800 GPa
NASA Astrophysics Data System (ADS)
Sakaiya, T.; Takahashi, H.; Kondo, T.; Shigemori, K.; Kadono, T.; Hironaka, Y.; Osaki, N.; Irifune, T.
2011-12-01
When we consider the structure of the Earth's interior, the sound velocity is one of the important physical properties of the interior materials because it can be directly compared with the seismological data which can yield the physical properties of the Earth's interior. Although it needs to measure the sound velocity of the interior material under high pressure and temperature, the sound velocity measurement of the materials on the condition over 200 GPa and 4000 K, such as the Earth's core condition, is technically difficult in static compression technique (e.g. diamond anvil cell: DAC) [1-3]. Therefore, in such higher pressure and temperature, dynamic compression technique, such as gas gun, is used. Although some works about the sound velocity of pure iron have been done by gas gun [4-6], it is not enough to discuss about the Earth's core which consists mainly of iron. We performed laser-shock experiments of iron at GEKKO-XII Laser System HIPER irradiation facility in Institute of Laser Engineering, Osaka University (ILE) [7]. The laser-shock compression can generate pressures over 1TPa, which are much higher pressures than previous works by gas gun. The sound velocities of iron were measured by side-on radiography [6]. The laser-irradiated target (Fe) is backlit with an x ray emitted from a high-Z foil (Ti) that is located along the side of the target and that is irradiated by a separate laser. The intensity distribution of the x ray transmitted through the target is imaged onto an x-ray streak camera. When the motion of the front surface and rear surface of the target is obtained from the radiograph, we can obtain the velocity of the shock and rarefaction wave. The rarefaction wave propagates the target with the sound velocity. The pressure generated by the laser-shock compression is obtained from the shock velocity and particle velocity of the target. The particle velocity is obtained from the time revolution of the front surface in the radiograph. In this
Measurements of the sound velocity of shock-compressed liquid silica to 1100 GPa
NASA Astrophysics Data System (ADS)
McCoy, C. A.; Gregor, M. C.; Polsin, D. N.; Fratanduono, D. E.; Celliers, P. M.; Boehly, T. R.; Meyerhofer, D. D.
2016-12-01
The sound velocity in a shocked material provides information about its off-Hugoniot behavior of a material at high pressures. This information can be used to extend the knowledge gained in Hugoniot experiments and to model the re-shock and release behavior. Silica is one of the most important materials for equation of state studies because of its prevalence in the earth's interior and the well-defined properties of α-quartz. This article presents the sound velocity measurements of amorphous fused silica over the range 200 to 1100 GPa using laser-driven shocks and an α-quartz standard. These measurements demonstrate the technique proposed by Fratanduono et al. [J. Appl. Phys. 116, 033517 (2014)] to determine the sound velocity from the arrival of acoustic perturbations. The results compare favorably to the SESAME 7386 equation-of-state table. The Grüneisen parameter was calculated from the sound velocity data and found to be Γ=0.66 ±0.05 at densities above 6 g/cm3, an increase in precision by a factor of two over previous measurements.
Measurements of the sound velocity of shock-compressed liquid silica to 1100 GPa
McCoy, Chad August; Gregor, Michelle C.; Polsin, Danae N.; ...
2016-12-19
The sound velocity in a shocked material provides information about its off-Hugoniot behavior of a material at high pressures. This information can be used to extend the knowledge gained in Hugoniot experiments and to model the re-shock and release behavior. Silica is one of the most important materials for equation of state studies because of its prevalence in the earth’s interior and the well-defined properties of α-quartz. This paper presents sound velocity measurements of amorphous fused silica over the range 200 to 1100 GPa using laser-driven shocks and an α- quartz standard. These measurements demonstrate the technique proposed by Fratanduonomore » et al [J. Appl. Phys 116, 033517 (2014)] to determine the sound velocity from the arrival of acoustic perturbations. The results compare favorably to the SESAME 7386 equation-of-state table. The Grüneisen parameter was calculated from the sound velocity data and found to be Γ=0.66 ± 0.05 at densities above 6 g/cm3, an increase in precision by a factor of two over previous measurements.« less
Measurements of the sound velocity of shock-compressed liquid silica to 1100 GPa
McCoy, Chad August; Gregor, Michelle C.; Polsin, Danae N.; Fratanduono, Dayne E.; Celliers, Peter M.; Boehly, Thomas R.; Meyerhofer, David D.
2016-12-19
The sound velocity in a shocked material provides information about its off-Hugoniot behavior of a material at high pressures. This information can be used to extend the knowledge gained in Hugoniot experiments and to model the re-shock and release behavior. Silica is one of the most important materials for equation of state studies because of its prevalence in the earth’s interior and the well-defined properties of α-quartz. This paper presents sound velocity measurements of amorphous fused silica over the range 200 to 1100 GPa using laser-driven shocks and an α- quartz standard. These measurements demonstrate the technique proposed by Fratanduono et al [J. Appl. Phys 116, 033517 (2014)] to determine the sound velocity from the arrival of acoustic perturbations. The results compare favorably to the SESAME 7386 equation-of-state table. The Grüneisen parameter was calculated from the sound velocity data and found to be Γ=0.66 ± 0.05 at densities above 6 g/cm^{3}, an increase in precision by a factor of two over previous measurements.
Correction of sound velocity depending on the temperature for unconsolidated marine sediment
NASA Astrophysics Data System (ADS)
Kim, Dae-Choul
2016-04-01
laboratory sound velocity measurements with systematic temperature change on unconsolidated marine sediment have been performed to establish the precise correction curves between temperature and the sound velocity. Piston and box core samples recovered from the East Sea and the South Sea of Korea were used for the measurement. The core samples were cooled (at temperature of nearly 0℃) and the temperature was gradually increased (from 0℃ to 30℃) to measure sound velocity depending on the changes in temperature. The sediment texture and physical properties (porosity, water content, and bulk density) were measured separately at the same depth. The rate of velocity increase for muddy, silty, and sandy sediment are about 2.63 m/s/℃, 2.74 m/s/℃, and 2.96 m/s/℃, respectively. This is similar to the velocity change rate, 2.97 m/s/℃ presented by Del Grosso (1952). The samples used in this research, however, have relatively higher porosity than those of Del Grosso (1952). Thus, the possibility of discrepancy is differences in water content which affect the sound velocity and measurement system. We used recently developed digital velocity measurement system using PXI based on LabVIEW. We suggest to employ this correction for the accurate in situ geoacoustic property from laboratory data particularly for the deep cold water sample such as the East Sea sediment that has very low bottom water temperature about 0℃. Keywords : in situ geoacoustic property, temperature correction, East Sea Acknowledgements: This research was supported by the Agency for Defense Development (UD14003DD) and by "Marine geological and geophysical mapping of the Korean seas" of the Korea Institute of Geoscience and Mineral Resources (KIGAM).
The effects of pressure and temperature on sound velocity and density of Ni-S liquid
NASA Astrophysics Data System (ADS)
Terasaki, H. G.; Nishida, K.; Urakawa, S.; Uesugi, K.; Kuwabara, S.; Takubo, Y.; Shimoyama, Y.; Takeuchi, A.; Suzuki, Y.; Kono, Y.; Higo, Y.; Kondo, T.
2013-12-01
Sound velocity and density of the core material are indispensable properties to estimate a composition in the terrestrial core comparing with the observed seismic data. Here, we report these properties of Ni-S, which corresponds to the end-member of possible core composition Fe-Ni-S, at high pressure and temperature. These properties were measured based on simultaneous measurement of sound velocity and density combined with X-ray tomography technique. The experiments were carried out at X-ray computed micro-tomography (CT) beamlines (BL20XU, BL20B2), SPring-8 synchrotron radiation facility. Monochromatized X-ray of 51 keV passed through the sample cell and detected as a radiography image using CCD camera. X-ray radiography images from 0 to 180o were measured for CT measurement by rotating the press. An 80-ton uni-axial press was used to generate high pressure with using opposed-type cupped anvils (Urakawa et al. 2010). Density was determined by using X-ray absorption method obtained from the X-ray radiograph image. The sample thickness for the X-ray path can be directly obtained from the CT data. The sample density was also determined from the volume of the sample at high pressure and temperature. P-wave sound velocity was measured using pulse-echo overlapping ultrasonic method using LiNbO3 transducer attached backside of the anvil. We have successfully measured the sound velocity and density of Ni-S up to 1.5 GPa. Comparing with the previous results of liquid Fe-S, the effect of Ni on the sound velocity is minor but that on the density can not be negligible.
Using second-sound shock waves to probe the intrinsic critical velocity of liquid helium II
NASA Technical Reports Server (NTRS)
Turner, T. N.
1983-01-01
A critical velocity truly intrinsic to liquid helium II is experimentally sought in the bulk fluid far from the apparatus walls. Termed the 'fundamental critical velocity,' it necessarily is caused by mutual interactions which operate between the two fluid components and which are activated at large relative velocities. It is argued that flow induced by second-sound shock waves provides the ideal means by which to activate and isolate the fundamental critical velocity from other extraneous fluid-wall interactions. Experimentally it is found that large-amplitude second-sound shock waves initiate a breakdown in the superfluidity of helium II, which is dramatically manifested as a limit to the maximum attainable shock strength. This breakdown is shown to be caused by a fundamental critical velocity. Secondary effects include boiling for ambient pressures near the saturated vapor pressure or the formation of helium I boundary layers at higher ambient pressures. When compared to the intrinsic critical velocity discovered in highly restricted geometries, the shock-induced critical velocity displays a similar temperature dependence and is the same order of magnitude.
A model for sound velocity in a two-phase air-water bubbly flow
Chung, N.M.; Lin, W.K.; Pei, B.S.; Hsu, Y.Y. )
1992-07-01
In this paper, wave propagation in a homogeneous, low void fraction, two-phase air-water bubbly flow is analyzed through the compressibility of a single bubble to derive a P({rho}) relation; the dispersion relation is then derived by a homogeneous model. The phase velocity and attenuation calculated from the model are compared with existing data and are in good agreement. The momentum transfer effect is considered through the virtual mass term and is significant at a higher void fraction. The interfacial heat transfer between phases is significant at low frequency, while bubble scattering effects are important at high frequency (near resonance). Bubble behavior at both low and high frequency is derived based on the isothermal and the adiabatic cases, respectively. The phase velocity occurs at the limiting condition in both cases. Furthermore, resonance is present in the model, and the resonant frequency is determined.
Decremps, F; Belliard, L; Couzinet, B; Vincent, S; Munsch, P; Le Marchand, G; Perrin, B
2009-07-01
Recent improvements to measure ultrasonic sound velocities of liquids under extreme conditions are described. Principle and feasibility of picosecond acoustics in liquids embedded in a diamond anvils cell are given. To illustrate the capability of these advances in the sound velocity measurement technique, original high pressure and high temperature results on the sound velocity of liquid mercury up to 5 GPa and 575 K are given. This high pressure technique will certainly be useful in several fundamental and applied problems in physics and many other fields such as geophysics, nonlinear acoustics, underwater sound, petrology or physical acoustics.
NASA Astrophysics Data System (ADS)
Capstick, J. W.
2013-01-01
1. The nature of sound; 2. Elasticity and vibrations; 3. Transverse waves; 4. Longitudinal waves; 5. Velocity of longitudinal waves; 6. Reflection and refraction. Doppler's principle; 7. Interference. Beats. Combination tones; 8. Resonance and forced vibrations; 9. Quality of musical notes; 10. Organ pipes; 11. Rods. Plates. Bells; 12. Acoustical measurements; 13. The phonograph, microphone and telephone; 14. Consonance; 15. Definition of intervals. Scales. Temperament; 16. Musical instruments; 17. Application of acoustical principles to military purposes; Questions; Answers to questions; Index.
Khelladi, Hassina; Plantier, Frédéric; Daridon, Jean Luc
2010-08-01
An accurate technique for the sound velocity measurement in strongly dissipative liquids is elaborated. This technique is based upon high sensitive phase detection. Each medium, at a given temperature and pressure, is characterized by a specific phase shift due to the propagation of the ultrasonic wave within the analyzed medium. By tuning the insonation frequency of the ultrasonic signal, a succession of consecutive nulls of the output dc voltage generated by the phase detector is observed. Thus from the obtained series of frequency values, the sound velocity is computed. Numerous organic liquids, such as alcohols and alkanes, have been used to validate this experimental procedure. As the developed method is well suited for the sound velocity measurement in strongly dissipative liquids, measurements of compressional wave velocity in heavy oil are also carried out over the temperature range 10 degrees C to 50 degrees C. The experimental results agree well with those found in the literature. The accuracy of the developed method is estimated at about +/-0.3%.
Zhang, Xiulu; Liu, Zhongli; Jin, Ke; Xi, Feng; Yu, Yuying; Tan, Ye; Dai, Chengda; Cai, Lingcang
2015-02-07
The high-pressure solid phase stability of molybdenum (Mo) has been the center of a long-standing controversy on its high-pressure melting. In this work, experimental and theoretical researches have been conducted to check its solid phase stability under compression. First, we performed sound velocity measurements from 38 to 160 GPa using the two-stage light gas gun and explosive loading in backward- and forward-impact geometries, along with the high-precision velocity interferometry. From the sound velocities, we found no solid-solid phase transition in Mo before shock melting, which does not support the previous solid-solid phase transition conclusion inferred from the sharp drops of the longitudinal sound velocity [Hixson et al., Phys. Rev. Lett. 62, 637 (1989)]. Then, we searched its structures globally using the multi-algorithm collaborative crystal structure prediction technique combined with the density functional theory. By comparing the enthalpies of body centered cubic structure with those of the metastable structures, we found that bcc is the most stable structure in the range of 0–300 GPa. The present theoretical results together with previous ones greatly support our experimental conclusions.
Horizontal velocities of MSTIDs over Taiwan observed by continuous HF Doppler sounding
NASA Astrophysics Data System (ADS)
Fišer, Jiří; Chum, Jaroslav
2016-04-01
Medium scale traveling ionospheric disturbances (MSTIDs) are signatures of gravity waves (GWs) which propagatein the termosphere. Since GWs play an important role in the coupling between the lower atmospheric layers and the thermosphere it is important to study their properties and source mechanisms. In this contribution we present an experimental study focused on horizontal velocities of MSTIDs over Taiwan in the nearly two year long period starting in April 2014. We observe MSTIDs by multipath continuous HF Doppler sounding system. The movement of ionospheric plasma induced via collisions by gravity waves is detected as Doppler shift of the sounding radio signal. We investigate seasonal and diurnal variations of MSTIDs horizontal propagation parameters and compare them with horizontal wind model (HWM) and also compare them with results obtained in other locations in middle a low latitudes where similar HF Doppler sounding systems are installed.
A frequency-response-based method of sound velocity measurement in an impedance tube
NASA Astrophysics Data System (ADS)
Wang, Wenjie; Thomas, P. J.; Wang, Tongqing
2017-04-01
A stable and accurate new method for the measurement of the velocity of sound is proposed. The method is based on the characteristics of the frequency response measured at different positions in an impedance tube and it eliminates adverse effects caused by reflections from the transmitting transducer at the bottom of the impedance tube. A series of experiments is conducted, at different water temperatures, different positions in the impedance tube and under constant pressure, to validate the feasibility and stability of the new method. The new technique is also extended to hydrostatic pressure conditions with stable sound velocity. Our method generates an accurate measurement result in comparison to the estimated or average value obtained with currently existing methods. The novel method is suitable to be widely used in underwater acoustics.
Development for sound velocity and density measurements of liquid metal at high pressures
NASA Astrophysics Data System (ADS)
Terasaki, H.; Nishida, K.; Urakawa, S.; Uesugi, K.; Takubo, Y.; Kuwabara, S.; Nakatsuka, A.; Hoshino, M.; Kono, Y.; Higo, Y.; Kondo, T.
2012-12-01
Sound velocity and density of liquid Fe-alloys under high pressure is quite important physical property to estimate the amount of light elements in the terrestrial core from the seismic data. Here, we have developed the system for simultaneous measurement of sound velocity and density combined with X-ray tomography technique at high pressure and temperature. High pressure experiments were performed using 80-ton uni-axial press (Urakawa et al. 2010) installed at X-ray computed micro-tomography (CT) beamline (BL20B2), SPring-8 synchrotron radiation facility. High pressure was generated using opposed-type cupped anvils. We measured the sound velocity and density of solid FeSi at room temperature and those of solid and liquid Ni-S at high temperature. Experimental pressure was obtained from the volume of h-BN. CT measurement was carried out by rotating the press from 0 to 180o with 0.2-0.3o steps. Monochromatized X-ray of 51 keV was used. Density was determined by using X-ray absorption method based on the X-ray radiograph image. The sample thickness for the X-ray path can be directly obtained from the CT data. This is a big advantage for CT measurement. Sound velocity was measured using pulse-echo overlapping ultrasonic method. P-wave signals were generated and detected by LiNbO3 transducer attached backside of the anvil. We have successfully observed both P-wave and S-wave signals up to 1.5 GPa and 1673 K. We detected change of signal intensity and shape corresponding to melting of Ni-S sample.
Nowak, Konrad W; Markowski, Marek
2013-07-01
Non-destructive ultrasonic methods for testing biological materials are applied in medicine as well as in food engineering to determine the physical parameters and the quality of agricultural products and raw materials such as meat. The purpose of this work was to identify the simplest and the most accurate of five methods for sound velocity determination across the fibers of the porcine longissimus dorsi muscle. The through-transmission technique (TT) was used for ultrasound signal acquisition with 2MHz transducers. The first two methods (M1, M2) are based on the acquisition of a single ultrasound signal in the analyzed material, another two methods (M3, M4) rely on the acquisition of two ultrasound signals in samples with different thicknesses (two-distance method) and the last method (M5) involves the acquisition of a single ultrasound signal in the analyzed material and the acquisition of a single ultrasound signal in distilled water at the same distance between ultrasonic transducers (relative method). The results were processed by the nonparametric Kruskal-Wallis test and compared with published data. The mean values of sound velocity obtained with the use of the above methods in pork samples at post-storage, room and vital temperatures were as follows: method M1-1549.2/1581.7/1597.4m/s, method M2-1477.7/1509.8/1597.4m/s, method M3-1552.0/1599.0/1623.3m/s, method M4-1557.4/1598.3/1623.6m/s, method M5-1554.3/1583.7/1598m/s. The experiment indicates that the choice of method for determining sound velocity significantly influences the results. Two of the five analyzed methods (namely M3 and M4), which involved measurements of the time of sound wave propagation through samples of the same material with varied thickness, produced velocity values most consistent with published data.
Density and sound velocity of Fe-S liquids at high pressures
NASA Astrophysics Data System (ADS)
Jing, Z.; Sakamaki, T.; Yu, T.; Kono, Y.; Wang, Y.; Park, C.; Shen, G.
2011-12-01
Liquid iron is the dominant component in the Earth's outer core and possibly the cores (or outer cores) of other terrestrial planets like Moon, Mars, and Mercury. Seismological and geochemical observations suggest that light elements such as S, C, O, Si, H, etc may be present in the liquid cores. In order to constrain the abundances of light elements and understand their effects on the structure, dynamics, and evolution of planetary cores, it is crucial to determine the equation of state for Fe-light element alloying liquids under core conditions. However, density data on liquid Fe-light element alloys at core pressures are very limited and no sound velocity or bulk modulus data are available for these liquids at high pressures. This makes it difficult to extrapolate the equation of state to core pressures. As a result, density data on solid Fe alloys are often used in the literature to compare with seismological observations by making corrections for the volume of melting. In this study, we extend the density dataset for Fe-S liquids by measuring the density of liquid iron with 19wt% sulfur and 27wt% sulfur using the X-ray absorption technique in a DIA-type multianvil apparatus up to 7 GPa and 2173 K. Ion chambers and 2D X-ray radiographic images were used to measure intensities of the incident and transmitted monochromatic X-rays, with the photon energy optimized at 40 keV. The density was then determined from the Beer-Lambert law using the mass absorption coefficients. We have also developed techniques to directly measure the ultrasonic sound velocities in these liquids up to 5 GPa and 1773 K using a Paris-Edinburgh cell. The sound velocity was determined by measuring the travel time difference between the sample echo and the buffer rod echo using a waveform generator and a digital oscilloscope and by measuring the sample thickness using X-ray radiographic images. The combination of density and sound velocity data can provide tight constraints on the equation of
Cote, R.; Devos, A.
2005-05-15
We present a method for refractive indices and longitudinal sound velocity measurements from picosecond ultrasonic experiments made at different probe incidence angles. For transparent or semitransparent materials such as dielectrics or semiconductors, picosecond ultrasonic experiments can lead to oscillations in the reflectivity curves whose frequency depends on the refractive indices, the sound velocity and the experiments angle. From these data we establish a simple method for the calculation of the refractive indices and verify it on a GaAs sample. We show on fluorinated silica glass and aluminum nitride practical applications of this method on thin films. From two experiments we measure the refraction index and the sound velocity of these materials, with no assumption on the materials properties or on the sample layers' thicknesses. Here the materials are buried under a thin aluminum film. It illustrates the fact that the method can be applied to multilayers. From the same experiments we then derive the thickness of the layers. It shows that this method can render picosecond ultrasonic experiments independent from other characterization means.
Liquid structure and temperature invariance of sound velocity in supercooled Bi melt.
Emuna, M; Mayo, M; Greenberg, Y; Caspi, E N; Beuneu, B; Yahel, E; Makov, G
2014-03-07
Structural rearrangement of liquid Bi in the vicinity of the melting point has been proposed due to the unique temperature invariant sound velocity observed above the melting temperature, the low symmetry of Bi in the solid phase and the necessity of overheating to achieve supercooling. The existence of this structural rearrangement is examined by measurements on supercooled Bi. The sound velocity of liquid Bi was measured into the supercooled region to high accuracy and it was found to be invariant over a temperature range of ∼60°, from 35° above the melting point to ∼25° into the supercooled region. The structural origin of this phenomenon was explored by neutron diffraction structural measurements in the supercooled temperature range. These measurements indicate a continuous modification of the short range order in the melt. The structure of the liquid is analyzed within a quasi-crystalline model and is found to evolve continuously, similar to other known liquid pnictide systems. The results are discussed in the context of two competing hypotheses proposed to explain properties of liquid Bi near the melting: (i) liquid bismuth undergoes a structural rearrangement slightly above melting and (ii) liquid Bi exhibits a broad maximum in the sound velocity located incidentally at the melting temperature.
Liquid structure and temperature invariance of sound velocity in supercooled Bi melt
Emuna, M.; Mayo, M.; Makov, G.; Greenberg, Y.; Caspi, E. N.; Yahel, E.; Beuneu, B.
2014-03-07
Structural rearrangement of liquid Bi in the vicinity of the melting point has been proposed due to the unique temperature invariant sound velocity observed above the melting temperature, the low symmetry of Bi in the solid phase and the necessity of overheating to achieve supercooling. The existence of this structural rearrangement is examined by measurements on supercooled Bi. The sound velocity of liquid Bi was measured into the supercooled region to high accuracy and it was found to be invariant over a temperature range of ∼60°, from 35° above the melting point to ∼25° into the supercooled region. The structural origin of this phenomenon was explored by neutron diffraction structural measurements in the supercooled temperature range. These measurements indicate a continuous modification of the short range order in the melt. The structure of the liquid is analyzed within a quasi-crystalline model and is found to evolve continuously, similar to other known liquid pnictide systems. The results are discussed in the context of two competing hypotheses proposed to explain properties of liquid Bi near the melting: (i) liquid bismuth undergoes a structural rearrangement slightly above melting and (ii) liquid Bi exhibits a broad maximum in the sound velocity located incidentally at the melting temperature.
Measurements of Sound Velocity and Grüneisen Parameter in CH and MgO Shocked to Mbar Pressures
NASA Astrophysics Data System (ADS)
McCoy, C. A.; Gregor, M. C.; Polsin, D. N.; Boehly, T. R.; Meyerhofer, D. D.; Fratanduono, D. E.; Celliers, P. M.
2015-11-01
We present sound velocity measurements using an unsteady wave analysis to relate acoustic perturbations in a sample to those in a standard with known sound velocity and Grüneisen parameter. The contraction and dilation of perturbations in the shock velocities in each material provide information on the sound velocity. Experiments measured the sound velocity and Grüneisen parameter in shocked CH and MgO (periclase) relative to a quartz standard. Hugoniot measurements were also made for MgO shocked to the fluid state; a modified Us -up relation is presented. The results are compared to SESAME and LEOS tables for CH and MgO. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.
NASA Astrophysics Data System (ADS)
Jing, Z.; Wang, Y.; Yu, T.; Sakamaki, T.; Kono, Y.; Park, C.
2012-12-01
Liquid Fe-light element alloys are likely present in the Earth's outer core and the cores of other terrestrial planets and moons including Mercury, Mars, Earth's Moon, Ganymede, and Io, as suggested by geophysical and geochemical observations. In order to determine the abundances of light elements and their effects on the structure, dynamics, and evolution of planetary cores, it is crucial to determine the equation of state for Fe-X (X=S, Si, C, O, etc.) liquids under core conditions. However, equations of state for Fe-rich liquids are poorly constrained at planetary core pressures due to the scarcity of density data and the absence of sound velocity data for these liquids at high pressures. At GSECARS, we have developed techniques to directly measure the ultrasonic sound velocities of Fe-rich liquids at high pressures using both a Kawai-type multi-anvil apparatus and a Paris-Edinburgh cell. The sound velocity was determined by measuring the travel time difference between the sample echo and the buffer rod echo using a waveform generator and a digital oscilloscope and by measuring the sample thickness using X-ray radiographic images. X-ray diffraction was also used to determine the pressure of the experiments and to confirm the melting of the samples. Using this technique, we have successfully obtained sound velocities of three Fe-S liquid compositions (Fe-10wt%S, Fe-20wt%S, and Fe-27wt%S), two Fe-Si liquid compositions (Fe-17wt%Si and Fe-25wt%Si), and pure Fe liquid at high pressure and temperature conditions up to 8 GPa and 2073 K. Results show significant differences between Fe-S and Fe-Si liquids: (1) The velocity of liquid Fe decreases with increasing sulfur content, but increases with silicon content; (2) Velocity is nearly independent of temperature for Fe-S liquids, but decreases with increasing temperature for Fe-Si liquids. These data can provide tighter constraints on equations of state of Fe-light element liquids and adiabatic temperature gradients in
NASA Technical Reports Server (NTRS)
Dash, R.
1979-01-01
A theoretical model is presented of the effects of forward velocity of an aircraft at arbitrary subsonic speed on sound radiated from convecting monopole and dipole sources embedded in the jet flow. It is found that with increasing forward velocity there is a steadily increasing amplification (over the static case) of the sound radiated into the forward arc and a large reduction of the sound which is radiated into the rearward arc. The same trend is also shown to result when there is a reduction in the exhaust velocity, with, however, a further rise in amplification in the forward quadrant and a drop in attenuation in the aft quadrant.
Ultrafast Optical Measurements of Thermal Conductivity and Sound Velocity of Amorphous SiC
NASA Astrophysics Data System (ADS)
Hondongwa, Donald; Olasov, Lauren; Daly, Brian; King, Sean; Bielefeld, Jeff
2011-03-01
We present ultrafast optical measurements of longitudinal sound velocity and thermal transport in hydrogenated amorphous carbon (a-SiC:H) films. The films were grown on Si wafers by PECVD using combinations of methylsilanes and H2 and He diluent gases. The films were well characterized and found to have densities (1.0 -- 2.5 g cm-3) and dielectric constants (2.8 -- 7.2) that spanned a wide range of values. Prior to their measurement, the a-SiC:H films were coated with 40-70 nm of polycrystalline Al. The pump-probe measurements were performed at room temperature using a modelocked Ti:sapphire laser. Transient reflectivity changes that are associated with very high frequency sound waves (picosecond ultrasonics) and the cooling rate of the SiC sample (Time Domain Thermorerflectance (TDTR)) were measured. We extract values for the thermal conductivity and sound velocity of the SiC films, and analyze the results in terms of rigidity percolation effects within the SiC layers. This work was supported by NSF award DMR-0906753.
Hozumi, T.; Sato, H.; Watanabe, K.
1996-05-01
The sound velocity in gaseous pentafluoroethane (HFC-125, CF{sub 3}CHF{sub 2}) has been measured by means of a spherical acoustic resonator. Seventy-two sound-velocity values were measured with an uncertainty of {plus_minus}0.01% at temperatures form 273 to 343 K and pressures form 10 to 250 kPa. The ideal-gas specific heats and the second acoustic-virial coefficients have been determined on the basis of the sound-velocity measurements. The second virial coefficients calculated from the present sound-velocity measurements agree with literature values which were determined from PVT measurements by means of a Burnett method.
ERIC Educational Resources Information Center
Neeson, John F.; Austin, Stephen
1975-01-01
Describes a method for the measurement of the velocity of sound in various liquids based on the Raman-Nath theory of light-sound interaction. Utilizes an analog computer program to calculate the intensity of light scattered into various diffraction orders. (CP)
NASA Astrophysics Data System (ADS)
McCammon, Catherine; Caracas, Razvan; Glazyrin, Konstantin; Potapkin, Vasily; Kantor, Anastasia; Sinmyo, Ryosuke; Prescher, Clemens; Kupenko, Ilya; Chumakov, Aleksandr; Dubrovinsky, Leonid
2016-12-01
Sound velocities of bridgmanite measured in the laboratory are a key to deciphering the composition of the lower mantle. Here, we report Debye sound velocities determined using nuclear inelastic scattering (NIS) for one majorite composition (Mg0.82Fe0.18SiO3) and five bridgmanite compositions (Mg0.82Fe0.18SiO3, Mg0.86Fe0.14Si0.98Al0.02O3, Mg0.88Fe0.12SiO3, Mg0.6Fe0.4Si0.63Al0.37O3, Mg0.83Fe0.15Si0.98Al0.04O3) measured in a diamond anvil cell at pressures up to 89 GPa at room temperature. Debye sound velocities for majorite determined from NIS are consistent with literature data from Brillouin scattering and ultrasonics, while Debye sound velocities for bridgmanite are significantly lower than literature values from the same methods. We calculated partial and total density of states (DOS) for MgSiO3 and FeSiO3 bridgmanite using density functional theory and demonstrate that Debye sound velocities calculated from the reduced DOS using the same approach as for the experimental data (i.e., the limit of D(E)/E2 as energy goes to zero) give the same sound velocities for each phase irrespective of which partial DOS is used. In addition, we show that Debye sound velocities calculated using this approach are consistent with values obtained from the calculation of the full elastic tensor. Comparison of the calculated DOS with the one obtained from NIS indicates that the experimental DOS has enhanced intensity at low energies that leads to a different slope of the DOS and hence a lower sound velocity. This effect is present in all of the bridgmanite samples examined in this study.
Carbon-depleted outer core revealed by sound velocity measurements of liquid iron-carbon alloy
NASA Astrophysics Data System (ADS)
Nakajima, Yoichi; Imada, Saori; Hirose, Kei; Komabayashi, Tetsuya; Ozawa, Haruka; Tateno, Shigehiko; Tsutsui, Satoshi; Kuwayama, Yasuhiro; Baron, Alfred Q. R.
2015-11-01
The relative abundance of light elements in the Earth's core has long been controversial. Recently, the presence of carbon in the core has been emphasized, because the density and sound velocities of the inner core may be consistent with solid Fe7C3. Here we report the longitudinal wave velocity of liquid Fe84C16 up to 70 GPa based on inelastic X-ray scattering measurements. We find the velocity to be substantially slower than that of solid iron and Fe3C and to be faster than that of liquid iron. The thermodynamic equation of state for liquid Fe84C16 is also obtained from the velocity data combined with previous density measurements at 1 bar. The longitudinal velocity of the outer core, about 4% faster than that of liquid iron, is consistent with the presence of 4-5 at.% carbon. However, that amount of carbon is too small to account for the outer core density deficit, suggesting that carbon cannot be a predominant light element in the core.
Experimental constraints on the thermodynamics and sound velocities of hcp-Fe to core pressures
NASA Astrophysics Data System (ADS)
Murphy, Caitlin A.; Jackson, Jennifer M.; Sturhahn, Wolfgang
2013-05-01
We report the high-pressure thermoelastic and vibrational thermodynamic parameters for hexagonal close-packed iron (ɛ-Fe), based on nuclear resonant inelastic X-ray scattering and in situ X-ray diffraction experiments at 300 K. Long data collection times, high-energy resolution, and quasi-hydrostatic sample conditions produced a high-statistical quality data set that comprises the volume-dependent phonon density of states (DOS) of ɛ-Fe at eleven compression points. From the integrated phonon DOS, we determine the Lamb-Mössbauer factor (fLM), average force constant (Φ), and vibrational entropy (Svib) of ɛ-Fe to pressures relevant to Earth's outer core. We find fLM = 0.923 ± 0.001 at 171 GPa, suggesting restricted thermal atomic motion at large compressions. We use Φ to approximate ɛ-Fe's pressure- and temperature-dependent reduced isotopic partition function ratios (β-factors), which provide information about the partitioning behavior of iron isotopes in equilibrium processes involving solid ɛ-Fe. In addition, we use the volume dependence of Svib to determine the product of ɛ-Fe's vibrational thermal expansion coefficient and isothermal bulk modulus, which we find to be pressure-independent and equal to 5.70 ± 0.05 MPa/K at 300 K. Finally, from the low-energy region of each phonon DOS, we determine the Debye sound velocity (vD), from which we derive the compressional (vP) and shear (vS) sound velocities of ɛ-Fe. We find vD = 5.60 ± 0.06, vP = 10.11 ± 0.12, and vS = 4.99 ± 0.06 km/s at 171 GPa, thus providing a new tight constraint on the density dependence of ɛ-Fe's sound velocities to outer core pressures.
Measuring the Speed of Sound through Gases Using Nitrocellulose
ERIC Educational Resources Information Center
Molek, Karen Sinclair; Reyes, Karl A.; Burnette, Brandon A.; Stepherson, Jacob R.
2015-01-01
Measuring the heat capacity ratios, ?, of gases either through adiabatic expansion or sound velocity is a well established physical chemistry experiment. The most accurate experiments depend on an exact determination of sound origin, which necessitates the use of lasers or a wave generator, where time zero is based on an electrical trigger. Other…
Triblock copolymer P104 detailed behavior through a density, sound velocity and DLS study
NASA Astrophysics Data System (ADS)
Bravo-Anaya, L. M.; Fierro-Castro, C.; Rharbi, Y.; Martínez, J. F. A. Soltero
2014-05-01
Pluronic triblock copolymers usually present complex phase behavior depending on the number of PEO and PPO blocks contained in the polymer. They have a great dependence to temperature and concentration, both considered as key factors in the pluronic phase behavior. The evaluation of physicochemical properties such as densimetry and sound velocity, as well as the determination of the size distribution profile of particles of P-104/water in solution allow obtaining a detailed temperature-concentration behavior of the system. In this work we present a study of P104/water behavior through density, ultrasound velocity and dynamic slight scattering (DLS) measurements in a wide range of temperatures. The critical micellar temperature (CMT) and the sphere-to-rod micelle transition temperature (GMT) were determinate as a function of concentration.
Velocity and bottom-stress measurements in the bottom boundary layer, outer Norton Sound, Alaska.
Cacchione, D.A.; Drake, D.E.; Wiberg, P.
1982-01-01
We have used long-term measurements of near-bottom velocities at four heights above the sea floor in Norton Sound, Alaska, to compute hourly values of shear velocity u., roughness and bottom-drag coefficient. Maximum sediment resuspension and transport, predicted for periods when the computed value of u. exceeds a critical level, occur during peak tidal currents associated with spring tides. The fortnightly variation in u. is correlated with a distinct nepheloid layer that intensifies and thickens during spring tides and diminishes and thins during neap tides. The passage of a storm near the end of the experiment caused significantly higher u. values than those found during fair weather.-from Authros
Sound Velocity Measurement of Stishovite at High Pressures up to 19 GPa
NASA Astrophysics Data System (ADS)
Zhou, C.; Jin, Z.; Wang, Y.; Zhang, Y.; WANG, C.
2015-12-01
An experimental system for measurement of the elastic wave velocities of solid polycrystalline samples at high pressures has been installed at the State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences (Wuhan). The ultrasonic system with LiNbO3 transducer can both generate and receive high frequency (MHz) signal. Combination with a Walker-type multianvil, the travel time through the polycrystalline sample at high pressures can be obtained. We carried out sound velocity measurements on polycrystalline stishovite up to 19 GPa at room temperature. And the experimental result shows an acoustic softening at high pressures. The experimental technique provides the offline experimental measurement of various materials to the high pressures corresponding to the Earth's mantle transition zone.
Low Sound Velocity Contributing to the High Thermoelectric Performance of Ag8SnSe6
Li, Wen; Lin, Siqi; Ge, Binghui; Yang, Jiong; Zhang, Wenqing
2016-01-01
Conventional strategies for advancing thermoelectrics by minimizing the lattice thermal conductivity focus on phonon scattering for a short mean free path. Here, a design of slow phonon propagation as an effective approach for high‐performance thermoelectrics is shown. Taking Ag8SnSe6 as an example, which shows one of the lowest sound velocities among known thermoelectric semiconductors, the lattice thermal conductivity is found to be as low as 0.2 W m−1 K−1 in the entire temperature range. As a result, a peak thermoelectric figure of merit zT > 1.2 and an average zT as high as ≈0.8 are achieved in Nb‐doped materials, without relying on a high thermoelectric power factor. This work demonstrates not only a guiding principle of low sound velocity for minimal lattice thermal conductivity and therefore high zT, but also argyrodite compounds as promising thermoelectric materials with weak chemical bonds and heavy constituent elements. PMID:27980995
Revisit of the relationship between the elastic properties and sound velocities at high pressures
NASA Astrophysics Data System (ADS)
Wang, Chenju; Xiang, Shikai; Gu, Jianbing; Kuang, Xiaoyu; Yu, Yin; Yan, Xiaozhen; Chen, Haiyan
2014-09-01
The second-order elastic constants and stress-strain coefficients are defined, respectively, as the second derivatives of the total energy and the first derivative of the stress with respect to strain. Since the Lagrangian and infinitesimal strain are commonly used in the two definitions above, the second-order elastic constants and stress-strain coefficients are separated into two categories, respectively. In general, any of the four physical quantities is employed to characterize the elastic properties of materials without differentiation. Nevertheless, differences may exist among them at non-zero pressures, especially high pressures. Having explored the confusing issue systemically in the present work, we find that the four quantities are indeed different from each other at high pressures and these differences depend on the initial stress applied on materials. Moreover, the various relations between the four quantities depicting elastic properties of materials and high-pressure sound velocities are also derived from the elastic wave equations. As examples, we calculated the high-pressure sound velocities of cubic tantalum and hexagonal rhenium using these nexus. The excellent agreement of our results with available experimental data suggests the general applicability of the relations.
Trapping effect on the sound velocity of a multilayer Fermi gas
NASA Astrophysics Data System (ADS)
Salas, Patricia; Solís, M. A.
2015-03-01
We present the trapping effect on the behavior of the isothermal compressibility and sound velocity for an interactionless Fermi gas immersed in a periodic interconnected multilayer structure created by an external Dirac comb potential which can vary both in spacing and in the intensity that controls the impenetrability of the layer edge (the wall). At T = 0 , for a given layer width and respect to the free ideal Fermi gas values, the isothermal compressibility as a function of the impenetrability starts in one and then monotonically increases to reach a larger constant value which is width dependent. The sound velocity as a function of impenetrability starts in one and for a range of impenetrabilities shows a bump which suggests that the presence of the structure increases the speed. For a finite temperature, given a separation between the walls and several values of their impenetrabilities, both properties start their evolution in temperature from the ideal Fermi gas value, unfold at temperatures near and under TF, and then recover the behavior of a classical gas at higher temperatures. We acknowledge partial support from PAPIIT IN111613 and CONACyT 221030.
Li, Baosheng; Liebermann, Robert C.
2014-07-29
This paper reviews the progress of the technology of ultrasonic interferometry from the early 1950s to the present day. During this period of more than 60 years, sound wave velocity measurements have been increased from at pressures less than 1 GPa and temperatures less than 800 K to conditions above 25 GPa and temperatures of 1800 K. This is complimentary to other direct methods to measure sound velocities (such as Brillouin and impulsive stimulated scattering) as well as indirect methods (e.g., resonance ultrasound spectroscopy, static or shock compression, inelastic X-ray scattering). Newly-developed pressure calibration methods and data analysis procedures using a finite strain approach are described and applied to data for the major mantle minerals. The implications for the composition of the Earth’s mantle are discussed. The state-of-the-art ultrasonic experiments performed in conjunction with synchrotron X-radiation can provide simultaneous measurements of the elastic bulk and shear moduli and their pressure and temperature derivatives with direct determination of pressure. The current status and outlook/challenges for future experiments are summarized.
Revisit of the relationship between the elastic properties and sound velocities at high pressures
Wang, Chenju; Yan, Xiaozhen; Xiang, Shikai Chen, Haiyan; Gu, Jianbing; Yu, Yin; Kuang, Xiaoyu
2014-09-14
The second-order elastic constants and stress-strain coefficients are defined, respectively, as the second derivatives of the total energy and the first derivative of the stress with respect to strain. Since the Lagrangian and infinitesimal strain are commonly used in the two definitions above, the second-order elastic constants and stress-strain coefficients are separated into two categories, respectively. In general, any of the four physical quantities is employed to characterize the elastic properties of materials without differentiation. Nevertheless, differences may exist among them at non-zero pressures, especially high pressures. Having explored the confusing issue systemically in the present work, we find that the four quantities are indeed different from each other at high pressures and these differences depend on the initial stress applied on materials. Moreover, the various relations between the four quantities depicting elastic properties of materials and high-pressure sound velocities are also derived from the elastic wave equations. As examples, we calculated the high-pressure sound velocities of cubic tantalum and hexagonal rhenium using these nexus. The excellent agreement of our results with available experimental data suggests the general applicability of the relations.
Low Sound Velocity Contributing to the High Thermoelectric Performance of Ag8SnSe6.
Li, Wen; Lin, Siqi; Ge, Binghui; Yang, Jiong; Zhang, Wenqing; Pei, Yanzhong
2016-11-01
Conventional strategies for advancing thermoelectrics by minimizing the lattice thermal conductivity focus on phonon scattering for a short mean free path. Here, a design of slow phonon propagation as an effective approach for high-performance thermoelectrics is shown. Taking Ag8SnSe6 as an example, which shows one of the lowest sound velocities among known thermoelectric semiconductors, the lattice thermal conductivity is found to be as low as 0.2 W m(-1) K(-1) in the entire temperature range. As a result, a peak thermoelectric figure of merit zT > 1.2 and an average zT as high as ≈0.8 are achieved in Nb-doped materials, without relying on a high thermoelectric power factor. This work demonstrates not only a guiding principle of low sound velocity for minimal lattice thermal conductivity and therefore high zT, but also argyrodite compounds as promising thermoelectric materials with weak chemical bonds and heavy constituent elements.
Very low sound velocities in iron-rich (Mg,Fe)O : Implications for the core-mantle boundary region.
Wicks, J. K.; Jackson, J. M.; Sturhahn, W.; X-Ray Science Division; California Inst. of Tech.; Jet Propulsion Lab.
2010-08-10
The sound velocities of (Mg{sub .16}Fe{sub .84})O have been measured to 121 GPa at ambient temperature using nuclear resonant inelastic x-ray scattering. The effect of electronic environment of the iron sites on the sound velocities were tracked in situ using synchrotron Moessbauer spectroscopy. We found the sound velocities of (Mg{sub .16}Fe{sub .84})O to be much lower than those in other presumed mantle phases at similar conditions, most notably at very high pressures. Conservative estimates of the effect of temperature and dilution on aggregate sound velocities show that only a small amount of iron-rich (Mg,Fe)O can greatly reduce the average sound velocity of an assemblage. We propose that iron-rich (Mg,Fe)O be a source of ultra-low velocity zones. Other properties of this phase, such as enhanced density and dynamic stability, strongly support the presence of iron-rich (Mg,Fe)O in localized patches above the core-mantle boundary.
Sound Velocities of Iron-Nickel and Iron-Nickel-Silicon Alloys at High Pressure
NASA Astrophysics Data System (ADS)
Miller, R. A.; Jackson, J. M.; Sturhahn, W.; Zhao, J.; Murphy, C. A.
2014-12-01
Seismological and cosmochemical studies suggest Earth's core is primarily composed of iron with ~5 to 10 wt% nickel and some light elements [e.g. 1]. To date, the concentration of nickel and the amount and identity of light elements remain poorly constrained due in part to the difficulty of conducting experimental measurements at core conditions. The vibrational properties of a variety iron alloys paired with seismic observations can help better constrain the composition of the core. We directly measured the partial phonon density of states of bcc- and hcp-structured Fe0.9Ni0.1 and Fe0.85Ni0.1Si0.05 at high pressures. The samples were compressed using a panoramic diamond anvil cell. A subset of the experiments were conducted using neon as a pressure transmitting medium. Measurements of high statistical quality were performed with nuclear resonant inelastic x-ray scattering (NRIXS) at sector 3-ID-B of the Advanced Photon Source [2, 3, 4]. The unit cell volume of each sample was determined at each compression point with in-situ x-ray diffraction at sector 3-ID-B before and after each NRIXS measurement. The Debye, compressional, and shear sound velocities were determined from the low energy region of the partial phonon density of states paired with the volume measurements. We will present partial phonon density of states and sound velocities for Fe0.9Ni0.1 and Fe0.85Ni0.1Si0.05 at high-pressure and compare with those of pure iron. References: [1] McDonough, W.F. (2004): Compositional Model for the Earth's Core. Elsevier Ltd., Oxford. [2] Murphy, C.A., J.M. Jackson, W. Sturhahn, and B. Chen (2011): Melting and thermal pressure of hcp-Fe from the phonon density of states, Phys. Earth Planet. Int., doi:10.1016/j.pepi.2011.07.001. [3] Murphy, C.A., J.M. Jackson, W. Sturhahn, and B. Chen (2011): Grüneisen parameter of hcp-Fe to 171 GPa, Geophys. Res. Lett., doi:10.1029/2011GL049531. [4] Murphy, C.A., J.M. Jackson, and W. Sturhahn (2013): Experimental constraints on the
NASA Astrophysics Data System (ADS)
Nishida, Keisuke; Suzuki, Akio; Terasaki, Hidenori; Shibazaki, Yuki; Higo, Yuji; Kuwabara, Souma; Shimoyama, Yuta; Sakurai, Moe; Ushioda, Masashi; Takahashi, Eiichi; Kikegawa, Takumi; Wakabayashi, Daisuke; Funamori, Nobumasa
2016-08-01
Recent advances in techniques for high-pressure and high-temperature experiments enable us to measure the velocity of sound in liquid Fe alloys. However, reported velocities in liquid Fe-S differ among research groups (e.g., by >10% at 5 GPa), even when similar methods are used (i.e., the ultrasonic pulse-echo overlap method combined with a large volume press). To identify the causes of the discrepancies, we reanalyzed previous data and conducted additional sound velocity measurements for liquid Fe-S at 2-7 GPa, and evaluated the potential error sources. We found that the discrepancy cannot be explained by errors in the sound velocity measurements themselves, but by inaccuracies in determining the temperature, pressure, and chemical composition in each experiment. Of particular note are the significant errors introduced when determining pressures from the unit-cell volume of MgO, which is a temperature-sensitive pressure standard, using inaccurate temperatures. To solve the problem, we additionally used h-BN as a pressure standard, which is less sensitive to temperature. The pressure dependence of the sound velocity became smaller than that of the original data because of the revised pressure values. Our best estimate for the seismic velocity of the Moon's liquid outer core is 4.0 ± 0.1 km/s, given a chemical composition Fe83S17.
Specific heat and sound velocity at the relevant competing phase of high-temperature superconductors
Varma, Chandra M.; Zhu, Lijun
2015-01-01
Recent highly accurate sound velocity measurements reveal a phase transition to a competing phase in YBa2Cu3O6+δ that is not identified in available specific heat measurements. We show that this signature is consistent with the universality class of the loop current-ordered state when the free-energy reduction is similar to the superconducting condensation energy, due to the anomalous fluctuation region of such a transition. We also compare the measured specific heat with some usual types of transitions, which are observed at lower temperatures in some cuprates, and find that the upper limit of the energy reduction due to them is about 1/40th the superconducting condensation energy. PMID:25941376
Varma, Chandra M; Zhu, Lijun
2015-05-19
Recent highly accurate sound velocity measurements reveal a phase transition to a competing phase in YBa2Cu3O6+δ that is not identified in available specific heat measurements. We show that this signature is consistent with the universality class of the loop current-ordered state when the free-energy reduction is similar to the superconducting condensation energy, due to the anomalous fluctuation region of such a transition. We also compare the measured specific heat with some usual types of transitions, which are observed at lower temperatures in some cuprates, and find that the upper limit of the energy reduction due to them is about 1/40th the superconducting condensation energy.
Lucas, Marcel; Winey, J. M.; Gupta, Y. M.
2015-12-28
Previous reports of rapid phase transformation above 18 GPa [Erskine and Nellis, Nature 349, 317 (1991)] and large elastic waves below 18 GPa [Lucas et al., J. Appl. Phys. 114, 093515 (2013)] for shock-compressed ZYB-grade highly-oriented pyrolytic graphite (HOPG), but not for less oriented ZYH-grade HOPG, indicated a link between the orientational order dependence of the HOPG response above and below the phase transformation stress. To gain insight into this link and into the mechanical response of HOPG shocked to peak stresses approaching the phase transformation onset, the compressibility of ZYB- and ZYH-grade HOPG in the shocked state was examined using front surface impact experiments. Particle velocity histories and sound velocities were measured for peak stresses reaching 18 GPa. Although the locus of the measured peak stress-particle velocity states is indistinguishable for the two grades of HOPG, the measured sound velocities in the peak state reveal significant differences between the two grades. Specifically, 1) The measured sound velocities are somewhat higher for ZYH-grade HOPG, compared to ZYB-grade HOPG. 2) The measured sound velocities for ZYH-grade HOPG increase smoothly with compression, whereas those for ZYB-2 grade HOPG exhibit a significant reduction in the compression dependence from 12 GPa to 17 GPa and an abrupt increase from 17 GPa to 18 GPa. 3) The longitudinal moduli, determined from the measured sound velocities, are smaller than the calculated bulk moduli for ZYB-grade HOPG shocked to peak stresses above 15 GPa, indicating the onset of an elastic instability. The present findings demonstrate that the softening of the longitudinal modulus (or elastic instability) presented here is linked to the large elastic waves and the rapid phase transformation reported previously – all observed only for shocked ZYB-grade HOPG. The elastic instability in shocked ZYB-grade HOPG is likely a precursor to the rapid phase transformation observed above
NASA Astrophysics Data System (ADS)
Sugimoto, Tsuneyoshi; Nakagawa, Yutaka; Shirakawa, Takashi; Sano, Motoaki; Ohaba, Motoyoshi; Shibusawa, Sakae
2013-07-01
We propose a method for the monitoring and imaging of the water distribution in the rooting zone of plants using sound vibration. In this study, the water distribution measurement in the horizontal and vertical directions in the soil layer was examined to confirm whether a temporal change in the volume water content of the soil could be estimated from a temporal changes in propagation velocity. A scanning laser Doppler vibrometer (SLDV) is used for measurement of the vibration velocity of the soil surface, because the highly precise vibration velocity measurement of several many points can be carried out automatically. Sand with a uniform particle size distribution is used for the soil, as it has high plasticity; that is, the sand can return to a dry state easily even if it is soaked with water. A giant magnetostriction vibrator or a flat speaker is used as a sound source. Also, a soil moisture sensor, which measures the water content of the soil using the electric permittivity, is installed in the sand. From the experimental results of the vibration measurement and soil moisture sensors, we can confirm that the temporal changes of the water distribution in sand using the negative pressure irrigation system in both the horizontal and vertical directions can be estimated using the propagation velocity of sound. Therefore, in the future, we plan to develop an insertion-type sound source and receiver using the acceleration sensors, and we intend to examine whether our method can be applied even in commercial soil with growing plants.
Sound velocities of hydrous ringwoodite to 16 GPa and 673 K
Mao, Zhu; Lin, Jung-Fu; Jacobsen, Steven D.; Duffy, Thomas S.; Chang, Yun-Yuan; Smyth, Joseph R.; Frost, Daniel J.; Hauri, Erik H.; Prakapenka, Vitali B.
2012-05-10
To understand the effect of hydration on the sound velocities of major mantle minerals and to constrain the mantle's H{sub 2}O budget, we have measured the single-crystal elastic moduli of hydrous ringwoodite, (Mg{sub 1.633}Fe{sub 0.231}{sup 2+}Fe{sub 0.026}{sup 3+})Si{sub 1.00}H{sub 0.179}O{sub 4} with 1.1 wt.% H{sub 2}O using Brillouin scattering combined with X-ray diffraction in an externally-heated diamond anvil cell up to 16 GPa and 673 K. Up to 12 GPa at 300 K, the presence of 1.1 wt.% H{sub 2}O lowers the elastic moduli of ringwoodite by 5-9%, but does not affect the pressure derivatives of the elastic moduli compared to anhydrous ringwoodite. The reduction caused by hydration is significantly enhanced when temperatures are elevated at high pressures. At 12 GPa, increasing temperature by {Delta}T = 100 K leads to a 1.3-2.4% reduction in the elastic moduli (C{sub 11}, C{sub 12}, and C{sub 14}). Comparing our results with seismic observations, we have evaluated the potential H{sub 2}O content in the lower part of the transition zone. Our results indicate that the observed seismic velocity anomalies and related depth depression of the 660-km discontinuity could be attributed to thermal variations together with the presence of {approx} 0.1 wt.% H{sub 2}O.
NASA Astrophysics Data System (ADS)
Irifune, T.; Arimoto, T.
2015-12-01
Well-sintered polycrystalline aggregates are important as the specimens for sound velocity measurements with either ultrasonic interferometry or Brillouin scattering method. We recently developed techniques to synthesize translucent~transparent polycrystalline garnets at high very high pressure and temperature using Kawai-type multianvil apparatus. However, the grain sizes of these garnets remained significantly larger than 1 mm, which are not small enough for the measurements with GHz ultrasonic interferometry because of significant acoustic scattering by grain boundaries.We further developed the synthesis techniques and have succeeded to make well-sintered bodies of grossular and pyrope garnets made of nano-crystals (< 100 nm) at limited temperature ranges at a pressure of 15 GPa. Thus synthesized nano-polycrystalline garnets (NPG) are as transparent as the single crystals, having Real In-line Transmissions (RITs) close to those predicted by the refractive indices for the wide wave-length range in the visible light region.The present ultra-high pressure synthesis technique provides a new way to make transparent nano-polycrystalline minerals, which should be important not only for the mineral physics measurements but also for some industrial/scientific applications, such as novel photonic materials.
ERIC Educational Resources Information Center
Branca, Mario; Soletta, Isabella
2007-01-01
The velocity of sound in a gas depends on its temperature, molar mass, and [lambda] = C[subscript p]/C[subscript v], ratio (heat capacity at a constant pressure to heat capacity at constant volume). The [lambda] values for air, oxygen, nitrogen, argon, and carbon dioxide were determined by measuring the velocity of the sound through the gases at…
Lucas, Marcel; Winey, J. M.; Gupta, Y. M.
2015-12-28
Previous reports of rapid phase transformation above 18 GPa [Erskine and Nellis, Nature 349, 317 (1991)] and large elastic waves below 18 GPa [Lucas et al., J. Appl. Phys. 114, 093515 (2013)] for shock-compressed ZYB-grade highly-oriented pyrolytic graphite (HOPG), but not for less oriented ZYH-grade HOPG, indicated a link between the orientational order dependence of the HOPG response above and below the phase transformation stress. To gain insight into this link and into the mechanical response of HOPG shocked to peak stresses approaching the phase transformation onset, the compressibility of ZYB- and ZYH-grade HOPG in the shocked state was examinedmore » using front surface impact experiments. Particle velocity histories and sound velocities were measured for peak stresses reaching 18 GPa. Although the locus of the measured peak stress-particle velocity states is indistinguishable for the two grades of HOPG, the measured sound velocities in the peak state reveal significant differences between the two grades. Specifically, 1) The measured sound velocities are somewhat higher for ZYH-grade HOPG, compared to ZYB-grade HOPG. 2) The measured sound velocities for ZYH-grade HOPG increase smoothly with compression, whereas those for ZYB-2 grade HOPG exhibit a significant reduction in the compression dependence from 12 GPa to 17 GPa and an abrupt increase from 17 GPa to 18 GPa. 3) The longitudinal moduli, determined from the measured sound velocities, are smaller than the calculated bulk moduli for ZYB-grade HOPG shocked to peak stresses above 15 GPa, indicating the onset of an elastic instability. The present findings demonstrate that the softening of the longitudinal modulus (or elastic instability) presented here is linked to the large elastic waves and the rapid phase transformation reported previously – all observed only for shocked ZYB-grade HOPG. The elastic instability in shocked ZYB-grade HOPG is likely a precursor to the rapid phase transformation observed
Amoudache, Samira; Pennec, Yan Djafari Rouhani, Bahram; Khater, Antoine; Lucklum, Ralf; Tigrine, Rachid
2014-04-07
We theoretically investigate the potentiality of dual phononic-photonic (the so-called phoxonic) crystals for liquid sensing applications. We study the transmission through a two-dimensional (2D) crystal made of infinite cylindrical holes in a silicon substrate, where one row of holes oriented perpendicular to the propagation direction is filled with a liquid. The infiltrated holes may have a different radius than the regular holes. We show, in the defect structure, the existence of well-defined features (peaks or dips) in the transmission spectra of acoustic and optical waves and estimate their sensitivity to the sound and light velocity of the analyte. Some of the geometrical requirements behave in opposite directions when searching for an efficient sensing of either sound or light velocities. Hence, a compromise in the choice of the parameters may become necessary in making the phoxonic sensor.
Sound velocity of Fe-S liquids at high pressure: Implications for the Moon's molten outer core
Jing, Zhicheng; Wang, Yanbin; Kono, Yoshio; Yu, Tony; Sakamaki, Tatsuya; Park, Changyong; Rivers, Mark L.; Sutton, Stephen R.; Shen, Guoyin
2014-07-21
Sound velocities of Fe and Fe–S liquids were determined by combining the ultrasonic measurements and synchrotron X-ray techniques under high pressure–temperature conditions from 1 to 8 GPa and 1573 K to 1973 K. Four different liquid compositions were studied including Fe, Fe–10 wt% S, Fe–20 wt% S, and Fe–27 wt% S. Our data show that the velocity of Fe-rich liquids increases upon compression and decreases with increasing sulfur content, whereas temperature has negligible effect on the velocity of Fe–S liquids. The sound velocity data were combined with ambient-pressure densities to fit the Murnaghan equation of state (EOS). Compared to the lunar seismic model, our velocity data constrain the sulfur content at 4±3 wt%, indicating a significantly denser (6.5±0.5 g/cm^{3}) and hotter (1870-70+100 K) outer core than previously estimated. A new lunar structure model incorporating available geophysical observations points to a smaller core radius. Our model suggests a top–down solidification scenario for the evolution of the lunar core. Such “iron snow” process may have been an important mechanism for the growth of the inner core.
NASA Astrophysics Data System (ADS)
Steinheimer, J.; Bleicher, M.
2012-07-01
We analyze longitudinal pion spectra from √{s_{NN}}=2 GeV to &sqrt{s_{NN}}=20; GeV within Landau's hydrodynamical model and the UrQMD hybrid approach. From the measured data on the widths of the pion rapidity spectra, we extract the sound velocity c s 2 in the dense stage of the reactions. It is found that the sound velocity has a local minimum (indicating the softest point in the equation of state, EoS) at √{s_{NN}}=4-9 GeV, an energy range accessible at the Facility for Antiproton and Ion Research (FAIR) as well as the RHIC-Beam Energy Scan (RHIC-BES). This softening of the EoS is compatible with the formation of a QGP at the onset of deconfinement. The extracted sound velocities are then used to calculate an excitation function for the mean transverse mass of pions from the hybrid model. We find that, above √{s_{NN}} ≈ 10 GeV, even the lowest c s 2 gives a considerably larger < m_T > of pions compared to data.
Sakamaki, Tatsuya; Ohtani, Eiji; Fukui, Hiroshi; Kamada, Seiji; Takahashi, Suguru; Sakairi, Takanori; Takahata, Akihiro; Sakai, Takeshi; Tsutsui, Satoshi; Ishikawa, Daisuke; Shiraishi, Rei; Seto, Yusuke; Tsuchiya, Taku; Baron, Alfred Q R
2016-02-01
Hexagonal close-packed iron (hcp-Fe) is a main component of Earth's inner core. The difference in density between hcp-Fe and the inner core in the Preliminary Reference Earth Model (PREM) shows a density deficit, which implies an existence of light elements in the core. Sound velocities then provide an important constraint on the amount and kind of light elements in the core. Although seismological observations provide density-sound velocity data of Earth's core, there are few measurements in controlled laboratory conditions for comparison. We report the compressional sound velocity (V P) of hcp-Fe up to 163 GPa and 3000 K using inelastic x-ray scattering from a laser-heated sample in a diamond anvil cell. We propose a new high-temperature Birch's law for hcp-Fe, which gives us the V P of pure hcp-Fe up to core conditions. We find that Earth's inner core has a 4 to 5% smaller density and a 4 to 10% smaller V P than hcp-Fe. Our results demonstrate that components other than Fe in Earth's core are required to explain Earth's core density and velocity deficits compared to hcp-Fe. Assuming that the temperature effects on iron alloys are the same as those on hcp-Fe, we narrow down light elements in the inner core in terms of the velocity deficit. Hydrogen is a good candidate; thus, Earth's core may be a hidden hydrogen reservoir. Silicon and sulfur are also possible candidates and could show good agreement with PREM if we consider the presence of some melt in the inner core, anelasticity, and/or a premelting effect.
Roux, Philippe; Kuperman, W A; Cornuelle, Bruce D; Aulanier, Florian; Hodgkiss, W S; Song, Hee Chun
2013-04-01
Data collected over more than eight consecutive hours between two source-receiver arrays in a shallow water environment are analyzed through the physics of the waveguide invariant. In particular, the use of vertical arrays on both the source and receiver sides provides source and receiver angles in addition to travel-times associated with a set of eigenray paths in the waveguide. From the travel-times and the source-receiver angles, the eigenrays are projected into a group-velocity versus phase-velocity (Vg-Vp) plot for each acquisition. The time evolution of the Vg-Vp representation over the 8.5-h long experiment is discussed. Group speed fluctuations observed for a set of eigenrays with turning points at different depths in the water column are compared to the Brunt-Väisälä frequency.
NASA Astrophysics Data System (ADS)
Antonangeli, D.; Occelli, F.; Badro, J.; Requardt, H.; Fiquet, G.; Krisch, M.
2003-12-01
Seismological studies show that the Earth's inner core is elastically anisotropic. The anisotropy has an axial symmetry and an amplitude of about 3-4%, with the fast direction oriented parallel to the Earth's rotation axis. Several hypotheses have been proposed to explain this feature, but the lack of evidence from mineral physics does not allow to address them. Indeed, the experimental determination of sound velocity anisotropy in hcp-iron, the main constituent of the inner core, is of primary importance. Studies include first-principle calculations [1-5] and x-ray radial diffraction measurements [6], but the results show general disagreement, not only in magnitude, but in direction as well. We will report new inelastic x-ray scattering (IXS) data on polycrystalline hcp-iron as a function of pressure, complementing and extending previous IXS data [7]. The derived longitudinal and transverse sound velocities will be compared with the calculations and the experimental results present in literature. Furthermore, the issue of elastic anisotropy will be addressed. Taking advantage of the texturing developed by uniaxially compressed hcp-metals [8], and making use of a properly designed diamond anvil cell characterized by an angular aperture of more than \\begin{math} 90^{o} , we measured the sound velocity at 22 and 112 GPa in two different geometries with respect to the compression axis, probing the longitudinal sound propagation at \\begin{math} 50^{o} and \\begin{math} 90^{o} with respect to it. A difference in acoustic sound velocity of about 5% has been detected at the highest pressure. This effective anisotropy on a textured polycrystalline sample is comparable with the one observed in the Earth, further relaxing the requirement of a nearly perfect alignment of iron crystal grains sustained by previous theoretical investigations [1,4]. [1] L. Stixrude, R.E. Cohen, Science 267, 1972 (1995). [2] P. Soderlind et al., Phys. Rev. B 53, 14063 (1996). [3] R. E. Cohen et
NASA Astrophysics Data System (ADS)
Spichak, V. V.; Goidina, A. G.
2016-05-01
The neural network estimates of seismic P- and S-wave velocities from electrical resistivity of the rocks and, vice versa, resistivity estimates from seismic velocities are presented. It is shown that, depending on the ratio between the volumes of the known data and the data to be reconstructed, the accuracy of the estimates of the P- and S-wave velocities ranges within 1-4 and 4-6%, respectively. The logarithmic resistivity is estimated from seismic P- and S-velocities as accurately as up to 15-17%. In all cases, the biggest errors are obtained when the estimates are based on correlated data.
NASA Astrophysics Data System (ADS)
Iwase, Ryoichi
2016-07-01
An in situ method of estimating the seismic wave velocity at the seafloor surface by observing the particle motion of a wave transmitted into the sediment is presented; this method uses a sound source whose location is known. Conversely, a sound source localization method using the obtained seismic velocities and involving particle motion observation is also presented. Although this method is applicable only when the sound source exists within the critical incidence angle range, it is expected to contribute to the tracing of vocalizing baleen whales, which are unknown around Japanese waters.
NASA Astrophysics Data System (ADS)
Hirth, Michael; Kuhn, Jochen; Müller, Andreas
2015-02-01
Recent articles about smartphone experiments have described their applications as experimental tools in different physical contexts.1-4 They have established that smartphones facilitate experimental setups, thanks to the small size and diverse functions of mobile devices, in comparison to setups with computer-based measurements. In the experiment described in this article, the experimental setup is reduced to a minimum. The objective of the experiment is to determine the speed of sound with a high degree of accuracy using everyday tools. An article published recently proposes a time-of-flight method where sound or acoustic pulses are reflected at the ends of an open tube.5 In contrast, the following experiment idea is based on the harmonic resonant frequencies of such a tube, simultaneously triggered by a noise signal.
Spatial and temporal turbulent velocity and vorticity power spectra from sound scattering.
Seifer, Shahar; Steinberg, Victor
2005-04-01
By performing sound-scattering measurements with a detector array consisting of 62 elements in a flow between two counter-rotating disks we obtain the energy and vorticity power spectra directly in both spatial and temporal domains. Fast-accumulated statistics and a large signal-to-noise ratio allow us to get high-quality data rather effectively and to test scaling laws in details.
Song, Zhongchang; Zhang, Yu; Berggren, Per; Wei, Chong
2017-02-01
Computed tomography (CT) imaging and ultrasound experimental measurements were combined to reconstruct the acoustic properties (density, velocity, and impedance) of the head from a deceased Indo-Pacific humpback dolphin (Sousa chinensis). The authors extracted 42 soft forehead tissue samples to estimate the sound velocity and density properties at room temperature, 25.0 °C. Hounsfield Units (HUs) of the samples were read from CT scans. Linear relationships between the tissues' HUs and velocity, and HUs and density were revealed through regression analyses. The distributions of the head acoustic properties at axial, coronal, and sagittal cross sections were reconstructed, suggesting that the forehead soft tissues were characterized by low-velocity in the melon, high-velocity in the muscle and connective tissues. Further, the sound velocities of melon, muscle, and connective tissue pieces were measured under different temperatures to investigate tissues' velocity response to temperature. The results demonstrated nonlinear relationships between tissues' sound velocity and temperature. This study represents a first attempt to provide general information on acoustic properties of this species. The results could provide meaningful information for understanding the species' bioacoustic characteristics and for further investigation on sound beam formation of the dolphin.
NASA Astrophysics Data System (ADS)
Zheng, D.; Tanaka, S.; Miyazaki, K.; Takashiri, M.
2015-06-01
To investigate the effect of strain on specific heat, sound velocity and lattice thermal conductivity of nanocrystalline bismuth antimony telluride thin films, we performed both experimental study and modeling. The nanocrystalline thin films had mostly preferred crystal orientation along c-axis, and strains in the both directions of c-axis and a- b-axis. It was found that the thermal conductivity of nanocrystalline thin films decreased greatly as compared with that of bulk alloys. To gain insight into the thermal transport in the strained nanocrystalline thin films, we estimated the lattice thermal conductivity based on the phonon transport model of full distribution of mean free paths accounting for the effects of grain size and strain which was influenced to both the sound velocity and the specific heat. As a result, the lattice thermal conductivity was increased when the strain was shifted from compressive to tensile direction. We also confirmed that the strain was influenced by the lattice thermal conductivity but the reduction of the lattice thermal conductivity of thin films can be mainly attributed to the nano-size effect rather than the strain effect. Finally, it was found that the measured lattice thermal conductivities were in good agreement with modeling.
NASA Astrophysics Data System (ADS)
Li, Baosheng; Liebermann, Robert C.
2014-08-01
This paper reviews the progress of the technology of ultrasonic interferometry from the early 1950s to the present day. During this period of more than 60 years, sound wave velocity measurements have been increased from at pressures less than 1 GPa and temperatures less than 800 K to conditions above 25 GPa and temperatures of 1800 K. This is complimentary to other direct methods to measure sound velocities (such as Brillouin and impulsive stimulated scattering) as well as indirect methods (e.g., resonance ultrasound spectroscopy, static or shock compression, inelastic X-ray scattering). Newly-developed pressure calibration methods and data analysis procedures using a finite strain approach are described and applied to data for the major mantle minerals. The implications for the composition of the Earth’s mantle are discussed. The state-of-the-art ultrasonic experiments performed in conjunction with synchrotron X-radiation can provide simultaneous measurements of the elastic bulk and shear moduli and their pressure and temperature derivatives with direct determination of pressure. The current status and outlook/challenges for future experiments are summarized.
Jing, Z.; Wang, Y.; Yu, T.; Sakamaki, T.; Kono, Y.; Park, C.
2012-04-30
Liquid Fe-light element alloys are likely present in the Earth's outer core and the cores (or outer cores) of other terrestrial planets such as Moon, Mercury, and Mars, suggested by geophysical and geochemical observations. In order to determine the abundances of light elements and their effects on the structure, dynamics, and evolution of planetary cores, it is crucial to determine the equation of state for Fe-light element alloying liquids under core conditions. However, density data on liquid Fe-light element alloys at core pressures are very limited and no sound velocity or bulk modulus data are available for these liquids at high pressures. This makes it difficult to extrapolate the equation of state to core pressures. As a result, density data on solid Fe alloys are often used in the literature to compare with seismological observations by making rough corrections for the volume of melting. In this study, we determine the density and sound velocity for Fe-S liquids with different sulfur contents at high pressure and temperature conditions up to 8 GPa and 2173 K using synchrotron X-ray techniques.
Specifying heights and velocities of cloud motion from geostationary sounding data
NASA Technical Reports Server (NTRS)
Menzel, P.; Stewart, T. R.; Smith, W. L.
1983-01-01
Data from the geostationary Visible Infrared Spin-Scan Radiometer (VISSR) Atmospheric Sounder (VAS) for assigning simultaneous heights and velocities of cloud motion winds were processed. The following two techniques are discussed: The technique which delivers qualitative height assignments from imagery; and which uses the radiometric information contained in the VAS data to calculate quantitative heights.
Theory of Adiabatic Fountain Resonance
NASA Astrophysics Data System (ADS)
Williams, Gary A.
2017-01-01
The theory of "Adiabatic Fountain Resonance" with superfluid ^4{He} is clarified. In this geometry a film region between two silicon wafers bonded at their outer edge opens up to a central region with a free surface. We find that the resonance in this system is not a Helmholtz resonance as claimed by Gasparini et al., but in fact is a fourth sound resonance. We postulate that it occurs at relatively low frequency because the thin silicon wafers flex appreciably from the pressure oscillations of the sound wave.
Gartner, Jeffrey W.; Prych, E.A.; Tate, G.B.; Cacchione, D.A.; Cheng, R.T.; Bidlake, W.R.; Ferreira, J.T.
1998-01-01
Sinclair Inlet is a small embayment of Puget Sound in the State of Washington. The inlet, about 6.5 kilometers long and 1.5 kilometers wide, is the site of Puget Sound Naval Shipyard. There are concerns that bed sediments in the inlet may have been contaminated as a result of activities at the shipyard, and that these sediments could be resuspended by tide- and wind-driven currents and transported within the inlet or out of the inlet to other parts of Puget Sound. This study was conducted to provide information concerning the potential for sediment resuspension in the inlet. To obtain the necessary data, vertical profiles of water current from about 2 meters above the bed to 2 meters below the water surface were monitored with acoustic Doppler current profilers (ADCPs) at three locations during a 6.5-week winter period and a 4.5-week summer period in 1994. In addition, during the winter period, water velocites between 0.19 and 1.20 meters above the bed were measured with current meters using an instrument package called Geoprobe, which was deployed near one of the ADCPs. Other instruments on the Geoprobe measured light transmissivity, and a camera periodically took photographs of the bottom. Instruments on the Geoprobe and on the ADCPs also measured conductivity (for determining salinity), temperature, and pressure (for determinining tide). Samples of bed sediment and water samples for determining suspended-sediment concentration were collected at each of the current-measurement stations. Wind speed and direction were measured at three stations during a 12-month period, and tide was measured at one of these stations. Water currents measured at the three locations in Sinclair Inlet were relatively weak. Typical speeds were 5 to 10 centimeters per second, and the RMS (root-mean-square) speeds were less than 8 centimeters per second. Tidal and residual currents were of similar magnitude. Residual currents near the bottom typically were flowing in the opposite
NASA Technical Reports Server (NTRS)
Reed, S Albert
1922-01-01
There has been a tradition general among aeronautical engineers that a critical point exists for tip speeds at or near the velocity of sound, indicating a physical limit in the use of propellers at higher tip speeds; the idea being that something would occur analogous to what is known in marine propellers as cavitation. In the examination of the physics pertaining to both propellers and projectiles moving at or above 1100 feet per second, the conclusion was reached by the author that there is no reason for the existence of such a critical point and that, if it had been noted by observers it was not inherent in the phenomena revealed, but rather due to a particular shape or proportion of the projectile and that, with properly proportioned sections, it would not exist.
Oliynyk, Vitaliy; Jäger, Markus; Heimburg, Thomas; Buckin, Vitaly; Kaatze, Udo
2008-05-01
An experimental study of phosphocholine membranes made from one lipid, from mixtures of DPPC and DLPC, and also from lipids and small amounts of alamethicin is presented. We used atomic force microscopy to investigate the spatial organization and structure of lipid domains and also of the defects induced by the peptide. Alamethicin was found to alter the state of lipids in the gel state in a way that domains of fluid lipids are formed close to the defects. Differential calorimetry revealed phase characteristics of the lipid mixtures and the effect of small amounts of alamethicin on the phase behavior. It was also shown that the sound velocity profiles of the membranes suspensions can be well calculated from the heat capacity traces of the samples. This result confirms the correlation between the mechanical properties and the specific heat of membrane systems.
2008-09-01
showing shot locations (circles) and IMS hydrophone station locations ( triangles ), superimposed on a map of group velocities derived using average fall...E. McDonald (1991). Perth- Bermuda sound propagation (1960): Adiabatic mode interpretation, J. Acoust. Soc. Am. 90: 2586–2594. Jensen, F. B., W. A
NASA Astrophysics Data System (ADS)
Boness, David A.; Ware, Lucas
2017-01-01
Sound velocity-density systematics has long been a fruitful way to take shock wave measurements on elements, alloys, oxides, rocks, and other materials, and allow reasonable extrapolation to densities found deep in the Earth. Recent detection of super-Earths has expanded interest in terrestrial planetary interiors to an even greater range of materials and pressures. Recent published diamond anvil cell (DAC) experimental measurements of sound velocities in iron and iron alloys, relevant to planetary cores, are inconsistent with each other with regard to the validity of Birch's Law, a linear relation between sound velocity and density. We examine the range of validity of Birch's Law for several shocked metallic elements, including iron, and shocked ionic solids and make comparisons to the recent DAC data.
Sound Velocities at the Spin Crossover in (Mg0.75Fe0.25)O Ferropericlase
NASA Astrophysics Data System (ADS)
Sturhahn, W.; Lin, J.; Jackson, J. M.; Zhao, J.
2006-12-01
Iron-bearing minerals of the lower mantle like ferropericlase and silicate perovskite have recently been studied to evaluate the presence of pressure-dependent crossovers between the high-spin and the low-spin state of iron. Such a crossover was clearly observed in ferropericlase using x-ray emission spectroscopy [1,2], conventional Mössbauer spectroscopy [3], and synchrotron Mössbauer spectroscopy [4]. In the case of silicate perovskite, the electronic state of the iron has been studied with x-ray emission spectroscopy [5,6] and synchrotron Mössbauer spectroscopy [7] but the situation remains unclear. Also the influence of the spin crossover on sound velocities of the iron-bearing minerals of the lower mantle has not been studied experimentally. We applied nuclear resonant inelastic x-ray scattering to determine the vibrational density of states of Fe in (Mg0.75Fe0.25)O ferropericlase up to 110 GPa and ambient temperature. We observed a significant effect of the spin crossover in ferropericlase on its elasticity and sound velocities that can derived from the vibrational density of states. We will also briefly address the potential effects of high temperatures on the spin crossover in the framework of a recently suggested thermal population model [8]. This work is supported by the U.S. DOE-BES, Office of Science, under Contract No. W-31-109-Eng-38 and by NSF through COMPRESS. [1] Badro J. et al. (2003) Science 300, 789 [2] Lin J.-F. et al. (2005) Nature 436, 377 [3] Speziale S. et al. (2005) PNAS 102, 17918 [4] Lin J.-F. et al. (2006) Phys.Rev. B 73, 113107 [5] Li J. et al. (2004) PNAS 101, 14027 [6] Badro J. et al. (2004) Science 305, 383 [7] Jackson J.M. et al. (2005) American Mineral. 90, 199 [8] Sturhahn W. et al. (2005) Geophys.Res.Lett. 31, L12307
Effect of mean-velocity profile shapes on sound transmission through two-dimensional ducts
NASA Technical Reports Server (NTRS)
Hayfeh, A. H.; Kaiser, J. E.; Shaker, B. S.
1974-01-01
Acoustic propagation through a lined two-dimensional duct is examined in order to assess the influence of the shape of the mean-velocity profile on the attenuation rate. Five mean-velocity profiles are considered: linear, parabolic, Pohlhausen, 1/7th power law with a linear sub-layer, and linear with slip at the wall. It is shown that when the attenuation rate is tabulated as a function of the boundary-layer thickness, as is usually done, substantially different results are obtained from the several mean profiles. However, when the displacement thickness is used, a considerable collapse is achieved in the attenuation curves that are obtained from the various profiles. For downstream propagation, all profiles produce essentially the same results over a reasonable range of boundary-layer thickness. However, for many cases of upstream propagation, the results from the 'turbulent' boundary-layer profiles differ significantly from the results of the other profiles even when compared on the basis of displacement thickness.
Phonon Density of States and Sound Velocities of Magnesiow?stite in Earth's Lower Mantle
Lin, J; Jacosben, S D; Sturhahn, W; Jackson, J; Zhao, J; Yoo, C
2006-01-20
The partial phonon densities of states of iron in magnesiowuestite [(Mg{sub 0.75},Fe{sub 0.25})O] have been measured by nuclear inelastic X-ray scattering up to 109 GPa. Compressional and shear wave velocities, shear moduli, and their pressure derivatives increase significantly across the spin-pairing transition of iron in (Mg{sub 0.75},Fe{sub 0.25})O at approximately 50 GPa. The effects of the transition on the elastic properties of (Mg,Fe)O at lower-mantle pressures are in contrast to what was predicted by studying MgO and high-spin magnesiowuestite, and need to be considered in future geophysical modeling of the lower mantle. The transition also affects other thermodynamic properties of magnesiowuestite under high pressures.
Sound wave velocities of Fe-Ni alloy at high pressure and temperature
NASA Astrophysics Data System (ADS)
Kantor, A.; Dubrovinsky, L.; Kantor, I.; Kurnosov, A.; Kuznetsov, A.; Dubrovinskaia, N.; Krisch, M.
2006-12-01
Knowledge of high-pressure and high-temperature elasticity of Fe-Ni alloy with low (5-25%) Ni content is crucial for geosciences since it is probably the major component of the core of the Earth, Mars, Mercury, Moon, satellites of Saturn and Jupiter. High-pressure and high-temperature (up to 41 GPa and 700 K) study of FeNi alloy with 22% of Ni was carried out by mean of inelastic X-ray scattering (IXS) from polycrystalline material. Two sets of experiments: at room temperature and at 700 K have been performed. Before and after every measurement (taking about 10 hours) an in-situ 1-D monochromatic X-ray diffraction pattern was collected for volume determination exactly from the sample. X-ray diffraction study revealed stability of fcc over hcp phase in the whole studied P,T range. Isothermal equation of state was derived at room temperature and at 700 K. X-ray inelastic scattering measurements allow to calculate longitudinal acoustic wave velocity VL, that gives, combined with measured equations of state, full isotropic elasticity of the material. We did not observe strong deviations of fcc iron-nickel alloy bulk elasticity from elastic properties of pure hcp iron.
Liu, Jingfei; Declercq, Nico F
2017-03-01
An analytical and experimental study of the pulsed ultrasonic comb filtering effect is presented in this work intending to provide a fundamental tool for data analysis and phenomenon understanding in pulsed ultrasonics. The basic types of comb filter, feedforward and feedback filters, are numerically simulated and demonstrated. The characteristic features of comb filters, which include the formula for determining the locations of the spectral peaks or notches and the relationship between its temporal characteristics (relative time delay between constituent pulses) and its spectral characteristics (frequency interval between peaks or notches), are theoretically derived. To demonstrate the applicability of the comb filtering effect, it is applied to measuring the sound velocities and thickness of a thin plate sample. It is proven that the comb filtering effect based method not only is capable of accurate measurements, but also has advantages over the conventional time-of-flight based method in thin plate measurements. Furthermore, the principles developed in this study have potential applications in any pulsed ultrasonic cases where the output signal shows comb filter features.
NASA Astrophysics Data System (ADS)
Reeh, Niels; Mohr, Johan Jacob; Nørvang Madsen, Søren; Oerter, Hans; Gundestrup, Niels S.
Non-steady-state vertical velocities of up to 5 m a-1 exceed the vertical surface-parallel flow (SPF) components over much of the ablation area of Storstrømmen, a large outlet glacier from the East Greenland ice sheet. Neglecting a contribution to the vertical velocity of this magnitude results in substantial errors (up to 20%) also on the south-north component of horizontal velocities derived by satellite synthetic aperture radar interferometry (InSAR) measurements. In many glacier environments, the steady-state vertical velocity component required to balance the annual ablation rate is 5-10m a-1 or more.This indicates that the SPFassumption may be problematic also for glaciers in steady state. Here we derive the three-dimensional surface velocity distribution of Storstrømmen by using the principle of mass conservation (MC) to combine InSAR measurements from ascending and descending satellite tracks with airborne ice-sounding radar measurement of ice thickness. The results are compared to InSAR velocities previously derived by using the SPF assumption, and to velocities obtained by in situ global positioning system (GPS) measurements. The velocities derived by using the MC principle are in better agreement with the GPS velocities than the previously calculated velocities derived with the SPFassumption.
Optimizing Adiabaticity in NMR
NASA Astrophysics Data System (ADS)
Vandermause, Jonathan; Ramanathan, Chandrasekhar
We demonstrate the utility of Berry's superadiabatic formalism for numerically finding control sequences that implement quasi-adiabatic unitary transformations. Using an iterative interaction picture, we design a shortcut to adiabaticity that reduces the time required to perform an adiabatic inversion pulse in liquid state NMR. We also show that it is possible to extend our scheme to two or more qubits to find adiabatic quantum transformations that are allowed by the control algebra, and demonstrate a two-qubit entangling operation in liquid state NMR. We examine the pulse lengths at which the fidelity of these adiabatic transitions break down and compare with the quantum speed limit.
On black hole spectroscopy via adiabatic invariance
NASA Astrophysics Data System (ADS)
Jiang, Qing-Quan; Han, Yan
2012-12-01
In this Letter, we obtain the black hole spectroscopy by combining the black hole property of adiabaticity and the oscillating velocity of the black hole horizon. This velocity is obtained in the tunneling framework. In particular, we declare, if requiring canonical invariance, the adiabatic invariant quantity should be of the covariant form Iadia = ∮pi dqi. Using it, the horizon area of a Schwarzschild black hole is quantized independently of the choice of coordinates, with an equally spaced spectroscopy always given by ΔA = 8 π lp2 in the Schwarzschild and Painlevé coordinates.
Sakamaki, Tatsuya; Ohtani, Eiji; Fukui, Hiroshi; Kamada, Seiji; Takahashi, Suguru; Sakairi, Takanori; Takahata, Akihiro; Sakai, Takeshi; Tsutsui, Satoshi; Ishikawa, Daisuke; Shiraishi, Rei; Seto, Yusuke; Tsuchiya, Taku; Baron, Alfred Q. R.
2016-01-01
Hexagonal close-packed iron (hcp-Fe) is a main component of Earth’s inner core. The difference in density between hcp-Fe and the inner core in the Preliminary Reference Earth Model (PREM) shows a density deficit, which implies an existence of light elements in the core. Sound velocities then provide an important constraint on the amount and kind of light elements in the core. Although seismological observations provide density–sound velocity data of Earth’s core, there are few measurements in controlled laboratory conditions for comparison. We report the compressional sound velocity (VP) of hcp-Fe up to 163 GPa and 3000 K using inelastic x-ray scattering from a laser-heated sample in a diamond anvil cell. We propose a new high-temperature Birch’s law for hcp-Fe, which gives us the VP of pure hcp-Fe up to core conditions. We find that Earth’s inner core has a 4 to 5% smaller density and a 4 to 10% smaller VP than hcp-Fe. Our results demonstrate that components other than Fe in Earth’s core are required to explain Earth’s core density and velocity deficits compared to hcp-Fe. Assuming that the temperature effects on iron alloys are the same as those on hcp-Fe, we narrow down light elements in the inner core in terms of the velocity deficit. Hydrogen is a good candidate; thus, Earth’s core may be a hidden hydrogen reservoir. Silicon and sulfur are also possible candidates and could show good agreement with PREM if we consider the presence of some melt in the inner core, anelasticity, and/or a premelting effect. PMID:26933678
NASA Astrophysics Data System (ADS)
Bhatnagar, Shalabh
2017-01-01
Sound is an emerging source of renewable energy but it has some limitations. The main limitation is, the amount of energy that can be extracted from sound is very less and that is because of the velocity of the sound. The velocity of sound changes as per medium. If we could increase the velocity of the sound in a medium we would be probably able to extract more amount of energy from sound and will be able to transfer it at a higher rate. To increase the velocity of sound we should know the speed of sound. If we go by the theory of classic mechanics speed is the distance travelled by a particle divided by time whereas velocity is the displacement of particle divided by time. The speed of sound in dry air at 20 °C (68 °F) is considered to be 343.2 meters per second and it won't be wrong in saying that 342.2 meters is the velocity of sound not the speed as it's the displacement of the sound not the total distance sound wave covered. Sound travels in the form of mechanical wave, so while calculating the speed of sound the whole path of wave should be considered not just the distance traveled by sound. In this paper I would like to focus on calculating the actual speed of sound wave which can help us to extract more energy and make sound travel with faster velocity.
Adiabat-shaping in indirect drive inertial confinement fusion
Baker, K. L.; Robey, H. F.; Milovich, J. L.; Jones, O. S.; Smalyuk, V. A.; Casey, D. T.; MacPhee, A. G.; Pak, A.; Celliers, P. M.; Clark, D. S.; Landen, O. L.; Peterson, J. L.; Berzak-Hopkins, L. F.; Weber, C. R.; Haan, S. W.; Döppner, T. D.; Dixit, S.; Hamza, A. V.; Jancaitis, K. S.; Kroll, J. J.; and others
2015-05-15
Adiabat-shaping techniques were investigated in indirect drive inertial confinement fusion experiments on the National Ignition Facility as a means to improve implosion stability, while still maintaining a low adiabat in the fuel. Adiabat-shaping was accomplished in these indirect drive experiments by altering the ratio of the picket and trough energies in the laser pulse shape, thus driving a decaying first shock in the ablator. This decaying first shock is designed to place the ablation front on a high adiabat while keeping the fuel on a low adiabat. These experiments were conducted using the keyhole experimental platform for both three and four shock laser pulses. This platform enabled direct measurement of the shock velocities driven in the glow-discharge polymer capsule and in the liquid deuterium, the surrogate fuel for a DT ignition target. The measured shock velocities and radiation drive histories are compared to previous three and four shock laser pulses. This comparison indicates that in the case of adiabat shaping the ablation front initially drives a high shock velocity, and therefore, a high shock pressure and adiabat. The shock then decays as it travels through the ablator to pressures similar to the original low-adiabat pulses when it reaches the fuel. This approach takes advantage of initial high ablation velocity, which favors stability, and high-compression, which favors high stagnation pressures.
Kinetic Theory Derivation of the Adiabatic Law for Ideal Gases.
ERIC Educational Resources Information Center
Sobel, Michael I.
1980-01-01
Discusses how the adiabatic law for ideal gases can be derived from the assumption of a Maxwell-Boltzmann (or any other) distribution of velocities--in contrast to the usual derivations from thermodynamics alone, and the higher-order effect that leads to one-body viscosity. An elementary derivation of the adiabatic law is given. (Author/DS)
NASA Astrophysics Data System (ADS)
Salacuse, J. J.; Egelstaff, P. A.
2001-11-01
We describe a method for obtaining the intermediate scattering function I(Q,t) from a computer simulation: it is an extension of our earlier calculation [Salacuse, Denton, and Egelstaff, Phys. Rev. E 53, 2382 (1996)] for the t-->0 limit. We use this approach to obtain I(Q,t) for low Q and t from molecular dynamics (MD) simulations of a model krypton fluid whose atoms interact via a truncated Aziz pair potential, and the results are compared over their range of validity to I(Q,t) determined by the standard MD method and also by a time expansion approach. In its range of validity our approach is much more efficient than the standard MD method; however, it covers a restricted range of t due to the movement of density fluctuations (sound waves) through the simulated fluid which produces an anomaly in the time behavior of I(Q,t). By analyzing I(Q=0,t) the velocity of sound in the simulation is determined, and the results compare favorably with published experimental results for the sound velocity of liquid krypton.
Salacuse, J J; Egelstaff, P A
2001-11-01
We describe a method for obtaining the intermediate scattering function I(Q,t) from a computer simulation: it is an extension of our earlier calculation [Salacuse, Denton, and Egelstaff, Phys. Rev. E 53, 2382 (1996)] for the t-->0 limit. We use this approach to obtain I(Q,t) for low Q and t from molecular dynamics (MD) simulations of a model krypton fluid whose atoms interact via a truncated Aziz pair potential, and the results are compared over their range of validity to I(Q,t) determined by the standard MD method and also by a time expansion approach. In its range of validity our approach is much more efficient than the standard MD method; however, it covers a restricted range of t due to the movement of density fluctuations (sound waves) through the simulated fluid which produces an anomaly in the time behavior of I(Q,t). By analyzing I(Q=0,t) the velocity of sound in the simulation is determined, and the results compare favorably with published experimental results for the sound velocity of liquid krypton.
Wireless adiabatic power transfer
Rangelov, A.A.; Suchowski, H.; Silberberg, Y.; Vitanov, N.V.
2011-03-15
Research Highlights: > Efficient and robust mid-range wireless energy transfer between two coils. > The adiabatic energy transfer is analogous to adiabatic passage in quantum optics. > Wireless energy transfer is insensitive to any resonant constraints. > Wireless energy transfer is insensitive to noise in the neighborhood of the coils. - Abstract: We propose a technique for efficient mid-range wireless power transfer between two coils, by adapting the process of adiabatic passage for a coherently driven two-state quantum system to the realm of wireless energy transfer. The proposed technique is shown to be robust to noise, resonant constraints, and other interferences that exist in the neighborhood of the coils.
NASA Technical Reports Server (NTRS)
Schlosser, Herbert
1990-01-01
This paper is concerned with verification of the applicability of the Vinet et al. (1987) universal equation of state to the liquid phase of the rare-gas elements under pressure. As previously observed in solids and liquids metals, to a good approximation, in the absence of phase transitions, plots of the logarithms of the reduced pressure function, of the reduced sound velocity, and of the reduced bulk modulus, are all linear functions of 1 - X over the entire experimental pressure range. The results obtained on the rare-gas liquids are comparable in accuracy to those obtained in previous work on solids and liquid metals.
NASA Technical Reports Server (NTRS)
Schlosser, Herbert; Ferrante, John
1989-01-01
The previous work of Schlosser and Ferrante (1988) on universality in solids is extended to the study of liquid metals. As in the case of solids, to a good approximation, in the absence of phase transitions, plots of the logarithm of the reduced-pressure function H, of the reduced-isothermal-bulk-modulus function b, and of the reduced-sound-velocity function v are all linear in 1-X. Finally, it is demonstrated that ln(Cp/C/v) is also linear in 1-X, where X = (V/V/0/)exp 1/3), and V(0) is the volume at zero pressure.
NASA Astrophysics Data System (ADS)
Seibel, C.; Suedmeyer, J.; Fieback, T. M.
2014-07-01
Inline process control by measurement of velocity of sound of fluids is a direct and comprehensive technique [J. D. N. Cheeke and Z. Wang, "Acoustic wave gas sensors," Sens. Actuators B 59, 146-153 (1999); J. W. Grate, S. J. Martin, and R. M. White, "Acoustic wave microsensors," Anal. Chem. 65, 1868 (1993)]. Depending on the varying conditions of measuring fluid(s), temperatures and pressures, it is a challenging task to find the best possible acoustic setup. Taking this background into account, a velocity of sound measurement device for temperatures up to 475 K and pressures up to 24 MPa was designed and assembled that is to be used for testing different resonator types. Two bulk acoustic wave resonators out of the commonly used lead zirconatetitanate compound (PZT) were tested at different test fluids under temperatures up to 423.15 K and pressures up to 24 MPa [S. Gebhardt, L. Seffner, F. Schlenkirch, and A. Schönecker, "PZT thick films for sensor and actuator applications," J. Eur. Ceram. Soc. 27, 4177-4180 (2007)]. Initially the pure gases methane, ethane, carbon dioxide, nitrogen, and helium were measured, followed by multi-component gas mixtures. Beside methane-based binary and ternary gas mixtures, a quaternary gas mixture comprising methane, ethane, carbon dioxide, and helium was analyzed. Results for all measurement fluids in a broad temperature and pressure range show a relative deviation to theoretical values derived from GERG-2008 smaller than 0.5%.
Seibel, C; Suedmeyer, J; Fieback, T M
2014-07-01
Inline process control by measurement of velocity of sound of fluids is a direct and comprehensive technique [J. D. N. Cheeke and Z. Wang, "Acoustic wave gas sensors," Sens. Actuators B 59, 146-153 (1999); J. W. Grate, S. J. Martin, and R. M. White, "Acoustic wave microsensors," Anal. Chem. 65, 1868 (1993)]. Depending on the varying conditions of measuring fluid(s), temperatures and pressures, it is a challenging task to find the best possible acoustic setup. Taking this background into account, a velocity of sound measurement device for temperatures up to 475 K and pressures up to 24 MPa was designed and assembled that is to be used for testing different resonator types. Two bulk acoustic wave resonators out of the commonly used lead zirconatetitanate compound (PZT) were tested at different test fluids under temperatures up to 423.15 K and pressures up to 24 MPa [S. Gebhardt, L. Seffner, F. Schlenkirch, and A. Schönecker, "PZT thick films for sensor and actuator applications," J. Eur. Ceram. Soc. 27, 4177-4180 (2007)]. Initially the pure gases methane, ethane, carbon dioxide, nitrogen, and helium were measured, followed by multi-component gas mixtures. Beside methane-based binary and ternary gas mixtures, a quaternary gas mixture comprising methane, ethane, carbon dioxide, and helium was analyzed. Results for all measurement fluids in a broad temperature and pressure range show a relative deviation to theoretical values derived from GERG-2008 smaller than 0.5%.
Parallelizable adiabatic gate teleportation
NASA Astrophysics Data System (ADS)
Nakago, Kosuke; Hajdušek, Michal; Nakayama, Shojun; Murao, Mio
2015-12-01
To investigate how a temporally ordered gate sequence can be parallelized in adiabatic implementations of quantum computation, we modify adiabatic gate teleportation, a model of quantum computation proposed by Bacon and Flammia [Phys. Rev. Lett. 103, 120504 (2009), 10.1103/PhysRevLett.103.120504], to a form deterministically simulating parallelized gate teleportation, which is achievable only by postselection. We introduce a twisted Heisenberg-type interaction Hamiltonian, a Heisenberg-type spin interaction where the coordinates of the second qubit are twisted according to a unitary gate. We develop parallelizable adiabatic gate teleportation (PAGT) where a sequence of unitary gates is performed in a single step of the adiabatic process. In PAGT, numeric calculations suggest the necessary time for the adiabatic evolution implementing a sequence of L unitary gates increases at most as O (L5) . However, we show that it has the interesting property that it can map the temporal order of gates to the spatial order of interactions specified by the final Hamiltonian. Using this property, we present a controlled-PAGT scheme to manipulate the order of gates by a control qubit. In the controlled-PAGT scheme, two differently ordered sequential unitary gates F G and G F are coherently performed depending on the state of a control qubit by simultaneously applying the twisted Heisenberg-type interaction Hamiltonians implementing unitary gates F and G . We investigate why the twisted Heisenberg-type interaction Hamiltonian allows PAGT. We show that the twisted Heisenberg-type interaction Hamiltonian has an ability to perform a transposed unitary gate by just modifying the space ordering of the final Hamiltonian implementing a unitary gate in adiabatic gate teleportation. The dynamics generated by the time-reversed Hamiltonian represented by the transposed unitary gate enables deterministic simulation of a postselected event of parallelized gate teleportation in adiabatic
NASA Astrophysics Data System (ADS)
Nagakubo, A.; Ogi, H.; Ishida, H.; Hirao, M.; Yokoyama, T.; Nishihara, T.
2015-07-01
Vitreous silica (v-SiO2) shows anomalous temperature dependence of velocity, including positive temperature coefficient of velocity (TCV) and velocity minimum around 70 K. The former characteristic allows its application in acoustic-resonator devices as a temperature compensating material. In this paper, we study the temperature dependence of velocity of fluorine-doped v-SiO2 (v-SiO2-xFx) thin films using picosecond ultrasonic spectroscopy. To correct the temperature increase caused by irradiation with light pulses, we calculated the steady temperature increase in the measuring volume with a finite volume method, considering the temperature dependence of thermal conductivity, and find that temperature in the measurement region remains high even when the back surface is cryogenically cooled. Using the corrected temperature, we determine TCV of v-SiO2-xFx thin films for 0 < x < 0.264 , which increases as x increases and is smaller than reported bulk values by a factor of 0.5 - 0.7 . The velocity minimum is absent for the film with x = 0, but it is clearly observed at 70 K for the film with the highest fluorine concentration of x = 0.264. These temperature behaviors are attributed to the change in the Si-O-Si bond angle caused by the fluorine doping.
Jonsson, Thorin; Montealegre-Z, Fernando; Soulsbury, Carl D; Robson Brown, Kate A; Robert, Daniel
2016-09-01
The ear of the bush-cricket, Copiphora gorgonensis, consists of a system of paired eardrums (tympana) on each foreleg. In these insects, the ear is backed by an air-filled tube, the acoustic trachea (AT), which transfers sound from the prothoracic acoustic spiracle to the internal side of the eardrums. Both surfaces of the eardrums of this auditory system are exposed to sound, making it a directionally sensitive pressure difference receiver. A key feature of the AT is its capacity to reduce the velocity of sound propagation and alter the acoustic driving forces at the tympanum. The mechanism responsible for reduction in sound velocity in the AT remains elusive, yet it is deemed to depend on adiabatic or isothermal conditions. To investigate the biophysics of such multiple input ears, we used micro-scanning laser Doppler vibrometry and micro-computed X-ray tomography. We measured the velocity of sound propagation in the AT, the transmission gains across auditory frequencies and the time-resolved mechanical dynamics of the tympanal membranes in C. gorgonensis Tracheal sound transmission generates a gain of approximately 15 dB SPL, and a propagation velocity of ca 255 m s(-1), an approximately 25% reduction from free field propagation. Modelling tracheal acoustic behaviour that accounts for thermal and viscous effects, we conclude that reduction in sound velocity within the AT can be explained, among others, by heat exchange between the sound wave and the tracheal walls.
NASA Astrophysics Data System (ADS)
Kung, J.; Chien, Y. V.; Wu, W.; Dong, J.; Chang, Y.; Tsai, C.; Yang, M.; Wang, K.
2012-12-01
Previous studies showed that the voids and their geometry in the sedimentary rocks have great influence on the compressibility of rock, which reflects on its elastic velocities. Some models were developed to discuss the relations among velocity, porosity and void geometry. Therefore, the information of porosity, and void geometry and its distribution in rock is essential for understanding how the elastic properties of porous rocks affected by their poregeometry. In this study, we revisited a well-studied porous rock, Darley Dale sandstone, which has been studied by different groups with different purposes. Most of them are the deformation experiments. Different from previous studies, we measured the sound velocity of Darley dale sandstone under hydrostatic conditions. Also, we employed different techniques to investigate the pore geometry and porosity of Darley Dale sandstone to gain the insight of velocity changing behavior under the crustal conditions. Here, we measured a fully-dense copper block for a comparison. We performed X-ray CT scanning (XCT) to image the pore space of sandstone to construct the 3-D image of pore geometry, distribution and the pore size. The CT image data are allowed us to estimate the porosity of sandstone, too. One the other hand, the porosity of sample was measured using imbibitions method at ambient conditions and helium porosimeter at high pressure (up to 150 MPa). A set of specimens were cored from Darley Dale sandstone block. P and S wave velocities of specimens were measured at ambient conditions. We also performed high pressure velocity measurements on a selected rock specimen and a copper block up to 150 MPa under dry condition. Porosity of a set of rock specimens measured by imbibitions method was spanned from 6% to 15%, largely distributed within a range of 8%-11%. Compared the porosity obtained from three different techniques, imbibitions method, helium porosimeter and XCT, values from those measurements are in good agreement
Numerical simulations of solar spicules: Adiabatic and non-adiabatic studies
NASA Astrophysics Data System (ADS)
Kuźma, B.; Murawski, K.; Zaqarashvili, T. V.; Konkol, P.; Mignone, A.
2017-01-01
Aims: We aim to study the formation and evolution of solar spicules using numerical simulations of a vertical velocity pulse that is launched from the upper chromosphere. Methods: With the use of the PLUTO code, we numerically solved adiabatic and non-adiabatic magnetohydrodynamic (MHD) equations in 2D cylindrical geometry. We followed the evolution of spicules triggered by pulses that are launched in a vertical velocity component from the upper chromosphere. Then we compared the results obtained with and without non-adiabatic terms in the MHD equations. Results: Our numerical results reveal that the velocity pulse is steepened into a shock that propagates upward into the corona. The chromospheric cold and dense plasma follows the shock and rises into the corona with the mean speed of 20-25 km s-1. The nonlinear wake behind the pulse in the stratified atmosphere leads to quasi-periodic rebound shocks, which lead to quasi-periodic rising of chromospheric plasma into the corona with a period close to the acoustic cut-off period of the chromosphere. We found that the effect of non-adiabatic terms on spicule evolution is minor; the general properties of spicules such as their heights and rising-time remain slightly affected by these terms. Conclusions: In the framework of the axisymmetric model we devised, we show that the solar spicules can be triggered by the vertical velocity pulses, and thermal conduction and radiative cooling terms do not exert any significant influence on the dynamics of these spicules.
Quantum adiabatic machine learning
NASA Astrophysics Data System (ADS)
Pudenz, Kristen L.; Lidar, Daniel A.
2013-05-01
We develop an approach to machine learning and anomaly detection via quantum adiabatic evolution. This approach consists of two quantum phases, with some amount of classical preprocessing to set up the quantum problems. In the training phase we identify an optimal set of weak classifiers, to form a single strong classifier. In the testing phase we adiabatically evolve one or more strong classifiers on a superposition of inputs in order to find certain anomalous elements in the classification space. Both the training and testing phases are executed via quantum adiabatic evolution. All quantum processing is strictly limited to two-qubit interactions so as to ensure physical feasibility. We apply and illustrate this approach in detail to the problem of software verification and validation, with a specific example of the learning phase applied to a problem of interest in flight control systems. Beyond this example, the algorithm can be used to attack a broad class of anomaly detection problems.
Adiabatic capture and debunching
Ng, K.Y.; /Fermilab
2012-03-01
In the study of beam preparation for the g-2 experiment, adiabatic debunching and adiabatic capture are revisited. The voltage programs for these adiabbatic processes are derived and their properties discussed. Comparison is made with some other form of adiabatic capture program. The muon g-2 experiment at Fermilab calls for intense proton bunches for the creation of muons. A booster batch of 84 bunches is injected into the Recycler Ring, where it is debunched and captured into 4 intense bunches with the 2.5-MHz rf. The experiment requires short bunches with total width less than 100 ns. The transport line from the Recycler to the muon-production target has a low momentum aperture of {approx} {+-}22 MeV. Thus each of the 4 intense proton bunches required to have an emittance less than {approx} 3.46 eVs. The incoming booster bunches have total emittance {approx} 8.4 eVs, or each one with an emittance {approx} 0.1 eVs. However, there is always emittance increase when the 84 booster bunches are debunched. There will be even larger emittance increase during adiabatic capture into the buckets of the 2.5-MHz rf. In addition, the incoming booster bunches may have emittances larger than 0.1 eVs. In this article, we will concentrate on the analysis of the adiabatic capture process with the intention of preserving the beam emittance as much as possible. At this moment, beam preparation experiment is being performed at the Main Injector. Since the Main Injector and the Recycler Ring have roughly the same lattice properties, we are referring to adiabatic capture in the Main Injector instead in our discussions.
Bacon, Dave; Flammia, Steven T
2009-09-18
The difficulty in producing precisely timed and controlled quantum gates is a significant source of error in many physical implementations of quantum computers. Here we introduce a simple universal primitive, adiabatic gate teleportation, which is robust to timing errors and many control errors and maintains a constant energy gap throughout the computation above a degenerate ground state space. This construction allows for geometric robustness based upon the control of two independent qubit interactions. Further, our piecewise adiabatic evolution easily relates to the quantum circuit model, enabling the use of standard methods from fault-tolerance theory for establishing thresholds.
NASA Astrophysics Data System (ADS)
Hyung, Eugenia; Huang, Shichun; Petaev, Michail I.; Jacobsen, Stein B.
2016-04-01
The upper mantle is widely accepted to be pyrolitic, but the bulk composition of the lower mantle remains highly disputed. Recent modeling of the lower mantle shear wave velocity profile has suggested that the lower mantle is enriched in bridgmanite, therefore implying a higher Si/Mg than that of the upper mantle. We improve upon such modeling by taking into account Ca-perovskite and considering the distribution of Fe between bridgmanite and ferropericlase, more appropriate for Al-bearing systems. Using available experimental data, we derive a means to constrain Fe-Mg partitioning for bridgmanite and ferropericlase, constrain suitable values for the lower mantle, and apply these to lower mantle shear wave velocity calculations. Calculations that consider the effects of minor chemical components such as Ca and Al suggest that the lower mantle shear wave velocities can resolve PREM for a pyrolitic composition to within 1%. We also model chemical fractionations of the 147Sm-143Nd and 176Lu-176Hf systems induced by a crystallizing magma ocean that would produce a putative Si-enriched lower mantle. The comparison of the calculated 143Nd/144Nd and 176Hf/177Hf signatures with those of the terrestrial array shows that a Si-enriched lower mantle, if ever formed, no longer exists. Both mineralogical calculations and geochemical magma ocean modeling support the idea that the Earth's lower mantle is likely pyrolitic and that the mantle as a whole need not be chemically stratified.
Adiabatically implementing quantum gates
Sun, Jie; Lu, Songfeng Liu, Fang
2014-06-14
We show that, through the approach of quantum adiabatic evolution, all of the usual quantum gates can be implemented efficiently, yielding running time of order O(1). This may be considered as a useful alternative to the standard quantum computing approach, which involves quantum gates transforming quantum states during the computing process.
Semiconductor adiabatic qubits
Carroll, Malcolm S.; Witzel, Wayne; Jacobson, Noah Tobias; Ganti, Anand; Landahl, Andrew J.; Lilly, Michael; Nguyen, Khoi Thi; Bishop, Nathaniel; Carr, Stephen M.; Bussmann, Ezra; Nielsen, Erik; Levy, James Ewers; Blume-Kohout, Robin J.; Rahman, Rajib
2016-12-27
A quantum computing device that includes a plurality of semiconductor adiabatic qubits is described herein. The qubits are programmed with local biases and coupling terms between qubits that represent a problem of interest. The qubits are initialized by way of a tuneable parameter, a local tunnel coupling within each qubit, such that the qubits remain in a ground energy state, and that initial state is represented by the qubits being in a superposition of |0> and |1> states. The parameter is altered over time adiabatically or such that relaxation mechanisms maintain a large fraction of ground state occupation through decreasing the tunnel coupling barrier within each qubit with the appropriate schedule. The final state when tunnel coupling is effectively zero represents the solution state to the problem represented in the |0> and |1> basis, which can be accurately read at each qubit location.
NASA Astrophysics Data System (ADS)
Shimoyama, Yuta; Terasaki, Hidenori; Urakawa, Satoru; Takubo, Yusaku; Kuwabara, Soma; Kishimoto, Shunpachi; Watanuki, Tetsu; Machida, Akihiko; Katayama, Yoshinori; Kondo, Tadashi
2016-11-01
Carbon is one of the possible light elements in the cores of the terrestrial planets. The P wave velocity (VP) and density (ρ) are important factors for estimating the chemical composition and physical properties of the core. We simultaneously measured the VP and ρ of Fe-3.5 wt % C up to 3.4 GPa and 1850 K by using ultrasonic pulse-echo method and X-ray absorption methods. The VP of liquid Fe-3.5 wt % C decreased linearly with increasing temperature at constant pressure. The addition of carbon decreased the VP of liquid Fe by about 2% at 3 GPa and 1700 K and decreased the Fe density by about 2% at 2 GPa and 1700 K. The bulk modulus of liquid Fe-C and its pressure (P) and temperature (T) effects were precisely determined from directly measured ρ and VP data to be K0,1700 K = 83.9 GPa, dKT/dP = 5.9(2), and dKT/dT = -0.063 GPa/K. The addition of carbon did not affect the isothermal bulk modulus (KT) of liquid Fe, but it decreased the dK/dT of liquid Fe. In the ρ-VP relationship, VP increases linearly with ρ and can be approximated as VP (m/s) = -6786(506) + 1537(71) × ρ (g/cm3), suggesting that Birch's law is valid for liquid Fe-C at the present P-T conditions. Our results imply that at the conditions of the lunar core, the elastic properties of an Fe-C core are more affected by temperature than those of Fe-S core.
NASA Astrophysics Data System (ADS)
Pickl, Peter; Dürr, Detlef
2008-08-01
We give here a rigorous proof of the well known prediction of pair creation as it arises from the Dirac equation with an external time dependent potential. Pair creation happens with probability one if the potential changes adiabatically in time and becomes overcritical, which means that an eigenvalue curve (as a function of time) bridges the gap between the negative and positive spectral continuum. The potential can be thought of as being zero at large negative and large positive times. The rigorous treatment of this effect has been lacking since the pioneering work of Beck, Steinwedel and Süßmann [1] in 1963 and Gershtein and Zeldovich [8] in 1970.
Spatial adiabatic passage: a review of recent progress
NASA Astrophysics Data System (ADS)
Menchon-Enrich, R.; Benseny, A.; Ahufinger, V.; Greentree, A. D.; Busch, Th; Mompart, J.
2016-07-01
Adiabatic techniques are known to allow for engineering quantum states with high fidelity. This requirement is currently of large interest, as applications in quantum information require the preparation and manipulation of quantum states with minimal errors. Here we review recent progress on developing techniques for the preparation of spatial states through adiabatic passage, particularly focusing on three state systems. These techniques can be applied to matter waves in external potentials, such as cold atoms or electrons, and to classical waves in waveguides, such as light or sound.
Adiabatic regularisation of power spectra in k-inflation
Alinea, Allan L.; Kubota, Takahiro; Nakanishi, Yukari; Naylor, Wade E-mail: kubota@celas.osaka-u.ac.jp E-mail: naylor@phys.sci.osaka-u.ac.jp
2015-06-01
We look at the question posed by Parker et al. about the effect of UV regularisation on the power spectrum for inflation. Focusing on the slow-roll k-inflation, we show that up to second order in the Hubble and sound flow parameters, the adiabatic regularisation of such model leads to no difference in the power spectrum apart from certain cases that violate near scale-invariant power spectra. Furthermore, extending to non-minimal k-inflation, we establish the equivalence of the subtraction terms in the adiabatic regularisation of the power spectrum in Jordan and Einstein frames.
Geometry of the Adiabatic Theorem
ERIC Educational Resources Information Center
Lobo, Augusto Cesar; Ribeiro, Rafael Antunes; Ribeiro, Clyffe de Assis; Dieguez, Pedro Ruas
2012-01-01
We present a simple and pedagogical derivation of the quantum adiabatic theorem for two-level systems (a single qubit) based on geometrical structures of quantum mechanics developed by Anandan and Aharonov, among others. We have chosen to use only the minimum geometric structure needed for the understanding of the adiabatic theorem for this case.…
Adiabatic compressibility of myosin subfragment-1 and heavy meromyosin with or without nucleotide.
Tamura, Y; Suzuki, N; Mihashi, K
1993-01-01
The partial specific adiabatic compressibilities of myosin subfragment-1 (S1) and heavy meromyosin (HMM) of skeletal muscle in solution were determined by measuring the density and the sound velocity of the solution. The partial specific volumes of S1 and HMM were 0.713 and 0.711 cm3/g, respectively. The partial specific adiabatic compressibilities of S1 and HMM were 4.2 x 10(-12) and 2.9 x 10(-12) cm2/dyn, respectively. These values are in the same range as the most of globular proteins so far studied. The result indicates that the flexibility of S1 region almost equals to that of HMM. After binding to ADP.orthovanadate, S1 and HMM became softer than their complexes with ADP. The bulk moduli of S1 and HMM were of the order of (4-6) x 10(10) dyn/cm2, which are very comparable with the bulk modulus of muscle fiber. PMID:8298019
NASA Astrophysics Data System (ADS)
Bakaeva, Z.; Igamberdiev, K.; Khabibulaev, P.; Stepanek, P.; Cernoch, P.
This work reports the results of a study of the microstructural and dynamical properties of self-assembled triblock copolymers. It was performed using adiabatic calorimetry, ultrasonic spectroscopy and dynamic light scattering. In the vicinity of supramolecular transitions, first aggregates occur; with further increasing temperature a spontaneous forming of compact structures was observed in the system. These results are supported by data of the shear viscosity and free internal volume parameters calculated in the framework of the Frenkel-Andrade approach.
LETTERS AND COMMENTS: Adiabatic process reversibility: microscopic and macroscopic views
NASA Astrophysics Data System (ADS)
Anacleto, Joaquim; Pereira, Mário G.
2009-05-01
The reversibility of adiabatic processes was recently addressed by two publications. In the first (Miranda 2008 Eur. J. Phys. 29 937-43), an equation was derived relating the initial and final volumes and temperatures for adiabatic expansions of an ideal gas, using a microscopic approach. In that relation the parameter r accounts for the process reversibility, ranging between 0 and 1, which corresponds to the free and reversible expansion, respectively. In the second (Anacleto and Pereira 2009 Eur. J. Phys. 30 177-83), the authors have shown that thermodynamics can effectively and efficiently be used to obtain the general law for adiabatic processes carried out by an ideal gas, including compressions, for which r \\ge 1. The present work integrates and extends the aforementioned studies, providing thus further insights into the analysis of the adiabatic process. It is shown that Miranda's work is wholly valid for compressions. In addition, it is demonstrated that the adiabatic reversibility coefficient given in terms of the piston velocity and the root mean square velocity of the gas particles is equivalent to the macroscopic description, given just by the quotient between surroundings and system pressure values.
NASA Astrophysics Data System (ADS)
Elze, H.-Thomas; Kodama, Takeshi; Rafelski, Johann
1998-04-01
We consider an air bubble in water under conditions of single-bubble sonoluminescence (SBSL) and evaluate the emitted sound field nonperturbatively for subsonic gas-liquid interface motion. Sound emission being the dominant damping mechanism, we also implement the nonperturbative sound damping in the Rayleigh-Plesset equation for the interface motion. We evaluate numerically the sound pulse emitted during bubble collapse and compare the nonperturbative and perturbative results, showing that the usual perturbative description leads to an overestimate of the maximal surface velocity and maximal sound pressure. The radius vs time relation for a full SBSL cycle remains deceptively unaffected.
The Floquet Adiabatic Theorem revisited
NASA Astrophysics Data System (ADS)
Weinberg, Phillip; Bukov, Marin; D'Alessio, Luca; Kolodrubetz, Michael; Davidson, Shainen; Polkovnikov, Anatoli
2015-03-01
The existance of the adiabatic theorem for Floquet systems has been the subject of an active debate with different articles reaching opposite conclusions over the years. In this talk we clarify the situation by deriving a systematic expansion in the time-derivatives of a slow parameter for the occupation probabilities of the Floque states. Our analysis shows that the in a certain limit the transition between Floquet eigenstates are suppressed and it is possible to define an adiabatic theorem for Floquet systems. Crucially we observe however that the conditions for adiabaticity in ordinary and Floquet systems are different and that this difference can become important when the amplitude of the periodic driving is large. We illustrate our results with specific examples of a periodically driven harmonic oscillator and cold atoms in optical lattices which are relevant in current experiments.
Adiabatic losses in Stirling refrigerators
Bauwens, L.
1996-06-01
The Stirling cycle has been used very effectively in cryocoolers; but efficiencies relative to the Carnot limit are typically observed to peak for absolute temperature ratios of about two, which makes it less suitable for low-life refrigeration. The adiabatic loss appears to be responsible for poor performance at small temperature differences. In this paper, adiabatic losses are evaluated, for a temperature ratio of 2/3, taking into account the effect of phase angle between pistons, of volume ratio, of the distribution of the dead volume necessary to reduce the volume ratio, and of the distribution of displacement between expansion and compression spaces. The study is carried out numerically, using an adiabatic Stirling engine model in which cylinder flow is assumed to be stratified. Results show that the best location for the cylinder dead volume is on the compression side. Otherwise, all strategies used to trade off refrigeration for coefficient of performance are found to be roughly equivalent.
Adiabatic evolution of plasma equilibrium
Grad, H.; Hu, P. N.; Stevens, D. C.
1975-01-01
A new theory of plasma equilibrium is introduced in which adiabatic constraints are specified. This leads to a mathematically nonstandard structure, as compared to the usual equilibrium theory, in which prescription of pressure and current profiles leads to an elliptic partial differential equation. Topologically complex configurations require further generalization of the concept of adiabaticity to allow irreversible mixing of plasma and magnetic flux among islands. Matching conditions across a boundary layer at the separatrix are obtained from appropriate conservation laws. Applications are made to configurations with planned islands (as in Doublet) and accidental islands (as in Tokamaks). Two-dimensional, axially symmetric, helically symmetric, and closed line equilibria are included. PMID:16578729
Sliding seal materials for adiabatic engines
NASA Technical Reports Server (NTRS)
Lankford, J.
1985-01-01
The sliding friction coefficients and wear rates of promising carbide, oxide, and nitride materials were measured under temperature, environmental, velocity, loading conditions that are representative of the adiabatic engine environment. In order to provide guidance needed to improve materials for this application, the program stressed fundamental understanding of the mechanisms involved in friction and wear. Microhardness tests were performed on the candidate materials at elevated temperatures, and in atmospheres relevant to the piston seal application, and optical and electron microscopy were used to elucidate the micromechanisms of wear following wear testing. X-ray spectroscopy was used to evaluate interface/environment interactions which seemed to be important in the friction and wear process. Electrical effects in the friction and wear processes were explored in order to evaluate the potential usefulness of such effects in modifying the friction and wear rates in service. However, this factor was found to be of negligible significance in controlling friction and wear.
Pressure Oscillations in Adiabatic Compression
ERIC Educational Resources Information Center
Stout, Roland
2011-01-01
After finding Moloney and McGarvey's modified adiabatic compression apparatus, I decided to insert this experiment into my physical chemistry laboratory at the last minute, replacing a problematic experiment. With insufficient time to build the apparatus, we placed a bottle between two thick textbooks and compressed it with a third textbook forced…
Transitionless driving on adiabatic search algorithm
Oh, Sangchul; Kais, Sabre
2014-12-14
We study quantum dynamics of the adiabatic search algorithm with the equivalent two-level system. Its adiabatic and non-adiabatic evolution is studied and visualized as trajectories of Bloch vectors on a Bloch sphere. We find the change in the non-adiabatic transition probability from exponential decay for the short running time to inverse-square decay in asymptotic running time. The scaling of the critical running time is expressed in terms of the Lambert W function. We derive the transitionless driving Hamiltonian for the adiabatic search algorithm, which makes a quantum state follow the adiabatic path. We demonstrate that a uniform transitionless driving Hamiltonian, approximate to the exact time-dependent driving Hamiltonian, can alter the non-adiabatic transition probability from the inverse square decay to the inverse fourth power decay with the running time. This may open up a new but simple way of speeding up adiabatic quantum dynamics.
Transitionless driving on adiabatic search algorithm
NASA Astrophysics Data System (ADS)
Oh, Sangchul; Kais, Sabre
2014-12-01
We study quantum dynamics of the adiabatic search algorithm with the equivalent two-level system. Its adiabatic and non-adiabatic evolution is studied and visualized as trajectories of Bloch vectors on a Bloch sphere. We find the change in the non-adiabatic transition probability from exponential decay for the short running time to inverse-square decay in asymptotic running time. The scaling of the critical running time is expressed in terms of the Lambert W function. We derive the transitionless driving Hamiltonian for the adiabatic search algorithm, which makes a quantum state follow the adiabatic path. We demonstrate that a uniform transitionless driving Hamiltonian, approximate to the exact time-dependent driving Hamiltonian, can alter the non-adiabatic transition probability from the inverse square decay to the inverse fourth power decay with the running time. This may open up a new but simple way of speeding up adiabatic quantum dynamics.
Transitionless driving on adiabatic search algorithm.
Oh, Sangchul; Kais, Sabre
2014-12-14
We study quantum dynamics of the adiabatic search algorithm with the equivalent two-level system. Its adiabatic and non-adiabatic evolution is studied and visualized as trajectories of Bloch vectors on a Bloch sphere. We find the change in the non-adiabatic transition probability from exponential decay for the short running time to inverse-square decay in asymptotic running time. The scaling of the critical running time is expressed in terms of the Lambert W function. We derive the transitionless driving Hamiltonian for the adiabatic search algorithm, which makes a quantum state follow the adiabatic path. We demonstrate that a uniform transitionless driving Hamiltonian, approximate to the exact time-dependent driving Hamiltonian, can alter the non-adiabatic transition probability from the inverse square decay to the inverse fourth power decay with the running time. This may open up a new but simple way of speeding up adiabatic quantum dynamics.
Digital waveguide adiabatic passage part 1: theory
NASA Astrophysics Data System (ADS)
Vaitkus, Jesse A.; Steel, M. J.; Greentree, Andrew D.
2017-03-01
Spatial adiabatic passage represents a new way to design integrated photonic devices. In conventional adiabatic passage designs require smoothly varying waveguide separations. Here we show modelling of adiabatic passage devices where the waveguide separation is varied digitally. Despite digitisation, our designs show robustness against variations in the input wavelength and refractive index contrast of the waveguides relative to the cladding. This approach to spatial adiabatic passage opens new design strategies and hence the potential for new photonics devices.
High Rayleigh number heat transfer in a horizontal cylinder with adiabatic wall
NASA Technical Reports Server (NTRS)
Schiroky, G. H.; Rosenberger, F.
1984-01-01
The present investigation is concerned with an experimentally guided approach to the estimation of Nusselt numbers (Nu) at high Rayleigh numbers (Ra) for a cylinder with an adiabatic side wall. The Rayleigh number dependence of the Nusselt number for a horizontal cylinder with an adiabatic wall is presented in a graph. The obtained data are compared with results reported by Shih (1981). Shih has extended a three-term expansion for velocity and temperature distributions reported by Bejan and Tien (1978).
NASA Astrophysics Data System (ADS)
Dziarmaga, Jacek; Rams, Marek M.
2010-10-01
We consider an inhomogeneous quantum phase transition across a multicritical point of the XY quantum spin chain. This is an example of a Lifshitz transition with a dynamical exponent z=2. Just like in the case z=1 considered by Dziarmaga and Rams (2010 New J. Phys. 12 055007), when a critical front propagates much faster than the maximal group velocity of quasiparticles vq, then the transition is effectively homogeneous: the density of excitations obeys a generalized Kibble-Zurek mechanism and scales with the sixth root of the transition rate. However, unlike for the case z=1, the inhomogeneous transition becomes adiabatic not below vq but at a lower threshold velocity \\hat{v} , proportional to the inhomogeneity of the transition, where the excitations are suppressed exponentially. Interestingly, the adiabatic threshold \\hat{v} is nonzero despite the vanishing minimal group velocity of low-energy quasiparticles. In the adiabatic regime below \\hat{v} , the inhomogeneous transition can be used for efficient adiabatic quantum state preparation in a quantum simulator: the time required for the critical front to sweep across a chain of N spins adiabatically is merely linear in N, while the corresponding time for a homogeneous transition across the multicritical point scales with the sixth power of N. What is more, excitations after the adiabatic inhomogeneous transition, if any, are brushed away by the critical front to the end of the spin chain.
Non-adiabatic transition probability dependence on conical intersection topography
NASA Astrophysics Data System (ADS)
Malhado, João Pedro; Hynes, James T.
2016-11-01
We derive a closed form analytical expression for the non-adiabatic transition probability for a distribution of trajectories passing through a generic conical intersection (CI), based on the Landau-Zener equation for the non-adiabatic transition probability for a single straight-line trajectory in the CI's vicinity. We investigate the non-adiabatic transition probability's variation with topographical features and find, for the same crossing velocity, no intrinsic difference in efficiency at promoting non-adiabatic decay between peaked and sloped CIs, a result in contrast to the commonly held view. Any increased efficiency of peaked over sloped CIs is thus due to dynamical effects rather than to any increased transition probability of topographical origin. It is also shown that the transition probability depends in general on the direction of approach to the CI, and that the coordinates' reduced mass can affect the transition probability via its influence on the CI topography in mass-scaled coordinates. The resulting predictions compare well with surface hopping simulation results.
Non-adiabatic transition probability dependence on conical intersection topography.
Malhado, João Pedro; Hynes, James T
2016-11-21
We derive a closed form analytical expression for the non-adiabatic transition probability for a distribution of trajectories passing through a generic conical intersection (CI), based on the Landau-Zener equation for the non-adiabatic transition probability for a single straight-line trajectory in the CI's vicinity. We investigate the non-adiabatic transition probability's variation with topographical features and find, for the same crossing velocity, no intrinsic difference in efficiency at promoting non-adiabatic decay between peaked and sloped CIs, a result in contrast to the commonly held view. Any increased efficiency of peaked over sloped CIs is thus due to dynamical effects rather than to any increased transition probability of topographical origin. It is also shown that the transition probability depends in general on the direction of approach to the CI, and that the coordinates' reduced mass can affect the transition probability via its influence on the CI topography in mass-scaled coordinates. The resulting predictions compare well with surface hopping simulation results.
Experimental Investigation of Adiabatic Shear Banding at Different Impact Velocities
1993-01-01
obtained for XC18 steel are compared with results for a mild steel reported by Campbell and Ferguson [48] ; composition of En3B (British Standards...chemical composition of the supplied VAR4340 steel was as follows : C 0.42 ; Ni 1.74 ; Cr 0.89 ; Mn 0.46: Si 0.28 ; S 0.001 ; P 0.009 (% wt.). About...7] C. Fressengeas, Analyse dynamique 61asto-viscoplastique de l’h6tdrogdndit6 de la ddforma- tion plastique de cisalllement, Proc. Int. Conf. on
Calibration of sound velocimeter in pure water
NASA Astrophysics Data System (ADS)
Li, Zhiwei; Zhang, Baofeng; Li, Tao; Zhu, Junchao; Xie, Ziming
2016-01-01
Accurate measurement of sound speed is important to calibrate a sound velocity profiler which provides real-time sound velocity to the sonar equipment in oceanographic survey. The sound velocity profiler calculates the sound speed by measuring the time-of-flight of a 1 MHz single acoustic pulse to travel over about 300 mm path. A standard sound velocimeter instrument was invited to calibrate the sound velocity profiler in pure water at temperatures of 278,283, 288, 293, 298, 303 and 308K in a thermostatic vessel at one atmosphere. The sound velocity profiler was deployed in the thermostatic vessel alongside the standard sound velocimeter instrument and two platinum resistance thermometers (PRT) which were calibrated to 0.002k by comparison with a standard PRT. Time of flight circuit board was used to measure the time-of-flight to 22 picosecond precision. The sound speed which was measured by the sound velocity profiler was compared to the standard sound speed calculated by UNESCO to give the laboratory calibration coefficients and was demonstrated agreement with CTD-derived sound speed using Del Grosso's seawater equation after removing a bias.
NASA Astrophysics Data System (ADS)
Millán, Luis F.; Livesey, Nathaniel J.; Santee, Michelle L.; Neu, Jessica L.; Manney, Gloria L.; Fuller, Ryan A.
2016-09-01
This study investigates the representativeness of two types of orbital sampling applied to stratospheric temperature and trace gas fields. Model fields are sampled using real sampling patterns from the Aura Microwave Limb Sounder (MLS), the HALogen Occultation Experiment (HALOE) and the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS). The MLS sampling acts as a proxy for a dense uniform sampling pattern typical of limb emission sounders, while HALOE and ACE-FTS represent coarse nonuniform sampling patterns characteristic of solar occultation instruments. First, this study revisits the impact of sampling patterns in terms of the sampling bias, as previous studies have done. Then, it quantifies the impact of different sampling patterns on the estimation of trends and their associated detectability. In general, we find that coarse nonuniform sampling patterns may introduce non-negligible errors in the inferred magnitude of temperature and trace gas trends and necessitate considerably longer records for their definitive detection. Lastly, we explore the impact of these sampling patterns on tropical vertical velocities derived from stratospheric water vapor measurements. We find that coarse nonuniform sampling may lead to a biased depiction of the tropical vertical velocities and, hence, to a biased estimation of the impact of the mechanisms that modulate these velocities. These case studies suggest that dense uniform sampling such as that available from limb emission sounders provides much greater fidelity in detecting signals of stratospheric change (for example, fingerprints of greenhouse gas warming and stratospheric ozone recovery) than coarse nonuniform sampling such as that of solar occultation instruments.
NASA Astrophysics Data System (ADS)
Li, Dafa
2016-05-01
The adiabatic theorem was proposed about 90 years ago and has played an important role in quantum physics. The quantitative adiabatic condition constructed from eigenstates and eigenvalues of a Hamiltonian is a traditional tool to estimate adiabaticity and has proven to be the necessary and sufficient condition for adiabaticity. However, recently the condition has become a controversial subject. In this paper, we list some expressions to estimate the validity of the adiabatic approximation. We show that the quantitative adiabatic condition is invalid for the adiabatic approximation via the Euclidean distance between the adiabatic state and the evolution state. Furthermore, we deduce general necessary and sufficient conditions for the validity of the adiabatic approximation by different definitions.
Adiabatic theory of solitons fed by dispersive waves
NASA Astrophysics Data System (ADS)
Pickartz, Sabrina; Bandelow, Uwe; Amiranashvili, Shalva
2016-09-01
We consider scattering of low-amplitude dispersive waves at an intense optical soliton which constitutes a nonlinear perturbation of the refractive index. Specifically, we consider a single-mode optical fiber and a group velocity matched pair: an optical soliton and a nearly perfectly reflected dispersive wave, a fiber-optical analog of the event horizon. By combining (i) an adiabatic approach that is used in soliton perturbation theory and (ii) scattering theory from quantum mechanics, we give a quantitative account of the evolution of all soliton parameters. In particular, we quantify the increase in the soliton peak power that may result in the spontaneous appearance of an extremely large, so-called champion soliton. The presented adiabatic theory agrees well with the numerical solutions of the pulse propagation equation. Moreover, we predict the full frequency band of the scattered dispersive waves and explain an emerging caustic structure in the space-time domain.
Breaking of dynamical adiabaticity in direct laser acceleration of electrons
NASA Astrophysics Data System (ADS)
Robinson, A. P. L.; Arefiev, A. V.
2017-02-01
The interaction of an electron oscillating in an ion channel and irradiated by a plane electromagnetic wave is considered. It is shown that the interaction qualitatively changes with the increase of electron energy, as the oscillations across the channel become relativistic. The "square-wave-like" profile of the transverse velocity in the relativistic case enables breaking of the adiabaticity that precludes electron energy retention in the non-relativistic case. For an electron with a relativistic factor γ0, the adiabaticity breaks if ωL/ωp0≪√{γ0 } . Under these conditions, the kinetic energy acquired by the electron is retained once the interaction with the laser field ceases. This mechanism notably enables electron heating in regimes that do not require a resonant interaction between the initially oscillating electron and the laser electric field.
Adiabatic compressibility of an immiscible molten NaCl-AgI salt mixture
NASA Astrophysics Data System (ADS)
Stepanov, V. P.; Tkachev, N. K.; Kulik, N. P.; Peshkina, K. G.
2016-08-01
Adiabatic compressibility β of an immiscible 0.5NaCl + 0.5AgI liquid mixture in the immiscibility range is studied experimentally and theoretically using the model of charged hard spheres. The compressibility is calculated by the relationship β = 1/ u 2ρ studied using sound velocity u measured by a pulse method and density ρ determined by hydrostatic weighing. It is shown that the compressibility of the upper phase decreases and that of the lower phase increases when the temperature increases because of the superposition of the effects of the thermal motion of ions and the phase compositions. The temperature dependence of the difference between the compressibilities of the equilibrium phases is described using the empirical equation Δβ = ( T c- T)0.442, which is close to the mean-field theory description. The results of the model calculations adequately reproduce the experimentally observed temperature dependence of the compressibility of the coexisting phases. However, the theoretically predicted critical exponent (1/2) differs from the experimentally determined exponent by 13%. These results are discussed in terms of the nature of chemical bond in silver iodide.
The relationship between the adiabatic bulk modulus and enthalpy for mantle-related minerals
NASA Astrophysics Data System (ADS)
Anderson, Orson L.
1989-07-01
It is found that the adiabatic bulk modulus, KS, is linear with enthalpy over a wide temperature range: up to at least 1825 K, the present limit of the measurement of the bulk modulus. This correlation is shown to hold for Al2O3, MgO, and Mg2SiO4. Since the enthalpy is listed in thermodynamic tables up to 3000 K, one can reasonably safely extrapolate KS up to lower mantle temperatures using this correlation. This correlation was anticipated in a theoretical 1966 paper, where the definition of the anharmonic parameter δ S was made in terms of properties which vary with temperature, δ _s = - left( {1/{α K_S }} right)left( {{δ K}/{δ T}} right)_{P'} where α is the volume coefficient of thermal expansion. The correlation was first confirmed for polycrystalline oxides in an experimental 1966 paper. Since the isotropic shear modulus, G, is linear with T, it is possible to estimate the sound velocities in the temperature regime just below the melting point.
ERIC Educational Resources Information Center
Hinton, Leanne, Ed.; And Others
Sound symbolism is the study of the relationship between the sound of an utterance and its meaning. In this interdisciplinary collection of new studies, 24 leading scholars discuss the role of sound symbolism in a theory of language. Contributions and authors include the following: "Sound-Symbolic Processes" (Leanne Hinton, Johanna…
Adiabatic Wankel type rotary engine
NASA Technical Reports Server (NTRS)
Kamo, R.; Badgley, P.; Doup, D.
1988-01-01
This SBIR Phase program accomplished the objective of advancing the technology of the Wankel type rotary engine for aircraft applications through the use of adiabatic engine technology. Based on the results of this program, technology is in place to provide a rotor and side and intermediate housings with thermal barrier coatings. A detailed cycle analysis of the NASA 1007R Direct Injection Stratified Charge (DISC) rotary engine was performed which concluded that applying thermal barrier coatings to the rotor should be successful and that it was unlikely that the rotor housing could be successfully run with thermal barrier coatings as the thermal stresses were extensive.
Ultrafast adiabatic second harmonic generation
NASA Astrophysics Data System (ADS)
Dahan, Asaf; Levanon, Assaf; Katz, Mordechai; Suchowski, Haim
2017-03-01
We introduce a generalization of the adiabatic frequency conversion method for an efficient conversion of ultrashort pulses in the full nonlinear regime. Our analysis takes into account dispersion as well as two-photon processes and Kerr effect, allowing complete analysis of any three waves with arbitrary phase mismatched design and any nonlinear optical process. We use this analysis to design an efficient and robust second harmonic generation, the most widely used nonlinear process for both fundamental and applied research. We experimentally show that such design not only allows for very efficient conversion of various of ultrashort pulses, but is also very robust to variations in the parameters of both the nonlinear crystal and the incoming light. These include variation of more than 100 °C in the crystal temperature, a wide bandwidth of up to 75 nm and a chirp variation of 300 fs to 3.5 ps of the incoming pulse. Also, we show the dependency of the adiabatic second harmonic generation design on the pump intensity and the crystal length. Our study shows that two photon absorption plays a critical role in such high influence nonlinear dynamics, and that it must be considered in order to achieve agreement with experimental results.
Ultrafast adiabatic second harmonic generation.
Dahan, Asaf; Levanon, Assaf; Katz, Mordechai; Suchowski, Haim
2017-03-01
We introduce a generalization of the adiabatic frequency conversion method for an efficient conversion of ultrashort pulses in the full nonlinear regime. Our analysis takes into account dispersion as well as two-photon processes and Kerr effect, allowing complete analysis of any three waves with arbitrary phase mismatched design and any nonlinear optical process. We use this analysis to design an efficient and robust second harmonic generation, the most widely used nonlinear process for both fundamental and applied research. We experimentally show that such design not only allows for very efficient conversion of various of ultrashort pulses, but is also very robust to variations in the parameters of both the nonlinear crystal and the incoming light. These include variation of more than 100 °C in the crystal temperature, a wide bandwidth of up to 75 nm and a chirp variation of 300 fs to 3.5 ps of the incoming pulse. Also, we show the dependency of the adiabatic second harmonic generation design on the pump intensity and the crystal length. Our study shows that two photon absorption plays a critical role in such high influence nonlinear dynamics, and that it must be considered in order to achieve agreement with experimental results.
Vasil, Geoffrey M.; Lecoanet, Daniel; Brown, Benjamin P.; Zweibel, Ellen G.; Wood, Toby S.
2013-08-20
The speed of sound greatly exceeds typical flow velocities in many stellar and planetary interiors. To follow the slow evolution of subsonic motions, various sound-proof models attempt to remove fast acoustic waves while retaining stratified convection and buoyancy dynamics. In astrophysics, anelastic models typically receive the most attention in the class of sound-filtered stratified models. Generally, anelastic models remain valid in nearly adiabatically stratified regions like stellar convection zones, but may break down in strongly sub-adiabatic, stably stratified layers common in stellar radiative zones. However, studying stellar rotation, circulation, and dynamos requires understanding the complex coupling between convection and radiative zones, and this requires robust equations valid in both regimes. Here we extend the analysis of equation sets begun in Brown et al., which studied anelastic models, to two types of pseudo-incompressible models. This class of models has received attention in atmospheric applications, and more recently in studies of white-dwarf supernova progenitors. We demonstrate that one model conserves energy but the other does not. We use Lagrangian variational methods to extend the energy conserving model to a general equation of state, and dub the resulting equation set the generalized pseudo-incompressible (GPI) model. We show that the GPI equations suitably capture low-frequency phenomena in both convection and radiative zones in stars and other stratified systems, and we provide recommendations for converting low-Mach number codes to this equation set.
NASA Astrophysics Data System (ADS)
Vasil, Geoffrey M.; Lecoanet, Daniel; Brown, Benjamin P.; Wood, Toby S.; Zweibel, Ellen G.
2013-08-01
The speed of sound greatly exceeds typical flow velocities in many stellar and planetary interiors. To follow the slow evolution of subsonic motions, various sound-proof models attempt to remove fast acoustic waves while retaining stratified convection and buoyancy dynamics. In astrophysics, anelastic models typically receive the most attention in the class of sound-filtered stratified models. Generally, anelastic models remain valid in nearly adiabatically stratified regions like stellar convection zones, but may break down in strongly sub-adiabatic, stably stratified layers common in stellar radiative zones. However, studying stellar rotation, circulation, and dynamos requires understanding the complex coupling between convection and radiative zones, and this requires robust equations valid in both regimes. Here we extend the analysis of equation sets begun in Brown et al., which studied anelastic models, to two types of pseudo-incompressible models. This class of models has received attention in atmospheric applications, and more recently in studies of white-dwarf supernova progenitors. We demonstrate that one model conserves energy but the other does not. We use Lagrangian variational methods to extend the energy conserving model to a general equation of state, and dub the resulting equation set the generalized pseudo-incompressible (GPI) model. We show that the GPI equations suitably capture low-frequency phenomena in both convection and radiative zones in stars and other stratified systems, and we provide recommendations for converting low-Mach number codes to this equation set.
NASA Astrophysics Data System (ADS)
Kantor, Anastasia P.; Kantor, Innokenty Yu.; Kurnosov, Alexander V.; Kuznetsov, Alexei Yu.; Dubrovinskaia, Natalia A.; Krisch, Michael; Bossak, Alexei A.; Dmitriev, Vladimir P.; Urusov, Vadim S.; Dubrovinsky, Leonid S.
2007-09-01
Knowledge of the high-pressure and high-temperature elasticity of Fe-Ni alloy with low (5-25%) Ni content is crucial for geosciences since it is probably the major component of the cores of the terrestrial planets and the Moon. Here we present a study of a FeNi alloy with 22 at.% of Ni to 72 GPa and 715 K, using inelastic X-ray scattering (IXS) and X-ray powder diffraction from polycrystalline material. The X-ray diffraction (XRD) study revealed stability of the face centred cubic (fcc) over the hexagonal close packed (hcp) phase in the whole investigated pressure-temperature range. The study presents first investigations of elasticity of fcc phase of iron-nickel Fe 0.78Ni 0.22 alloy. The isothermal equations of state were derived at room temperature and at 715 K ( K300 = 162(1) GPa, K300=4.97(1), V300 = 6.89(1) cm 3/mol; K715 = 160(1) GPa, K715=4.97(2), V715 = 6.96(1) cm 3/mol). Inelastic X-ray measurements allow the determination of the longitudinal acoustic wave velocity VP, and provide, combined with the measured equations of state, the full isotropic elasticity of the material. We found that within experimental errors our data follow the Birch's law. We did not observe any significant deviations for fcc Fe 0.78Ni 0.22 from elastic properties of pure ɛ-iron.
Non-adiabatic pumping in an oscillating-piston model
NASA Astrophysics Data System (ADS)
Chuchem, Maya; Dittrich, Thomas; Cohen, Doron
2012-05-01
We consider the prototypical "piston pump" operating on a ring, where a circulating current is induced by means of an AC driving. This can be regarded as a generalized Fermi-Ulam model, incorporating a finite-height moving wall (piston) and non-trivial topology (ring). The amount of particles transported per cycle is determined by a layered structure of phase space. Each layer is characterized by a different drift velocity. We discuss the differences compared with the adiabatic and Boltzmann pictures, and highlight the significance of the "diabatic" contribution that might lead to a counter-stirring effect.
An interacting adiabatic quantum motor
NASA Astrophysics Data System (ADS)
Viola Kusminskiy, Silvia; Bruch, Anton; von Oppen, Felix
We consider the effect of electron-electron interactions on the performance of an adiabatic quantum motor based on a Thouless pump operating in reverse. We model such a device by electrons in a 1d wire coupled to a slowly moving periodic potential associated with the classical mechanical degree of freedom of the motor. This periodic degree of freedom is set into motion by a bias voltage applied to the 1d electron channel. We investigate the Thouless motor with interacting leads modeled as Luttinger liquids. We show that interactions enhance the energy gap opened by the periodic potential and thus the robustness of the Thouless motor against variations in the chemical potential. We show that the motor degree of freedom can be described as a mobile impurity in a Luttinger liquid obeying Langevin dynamics with renormalized coefficients due to interactions, for which we give explicit expressions.
Quantum and classical dynamics in adiabatic computation
NASA Astrophysics Data System (ADS)
Crowley, P. J. D.; Äńurić, T.; Vinci, W.; Warburton, P. A.; Green, A. G.
2014-10-01
Adiabatic transport provides a powerful way to manipulate quantum states. By preparing a system in a readily initialized state and then slowly changing its Hamiltonian, one may achieve quantum states that would otherwise be inaccessible. Moreover, a judicious choice of final Hamiltonian whose ground state encodes the solution to a problem allows adiabatic transport to be used for universal quantum computation. However, the dephasing effects of the environment limit the quantum correlations that an open system can support and degrade the power of such adiabatic computation. We quantify this effect by allowing the system to evolve over a restricted set of quantum states, providing a link between physically inspired classical optimization algorithms and quantum adiabatic optimization. This perspective allows us to develop benchmarks to bound the quantum correlations harnessed by an adiabatic computation. We apply these to the D-Wave Vesuvius machine with revealing—though inconclusive—results.
... may be a sign of early bowel obstruction. Causes Most of the sounds you hear in your stomach and intestines are ... a list of more serious conditions that can cause abnormal bowel sounds. Hyperactive, hypoactive, or missing bowel sounds may be ...
On the response of quasi-adiabatic particles to magnetotail reconfigurations
NASA Astrophysics Data System (ADS)
Delcourt, Dominique C.; Malova, Helmi V.; Zelenyi, Lev M.
2017-01-01
We investigate the response of quasi-adiabatic particles to dynamical reconfigurations of the magnetotail field lines. Although they travel through a sharp field reversal with a characteristic length scale smaller than their Larmor radii, these quasi-adiabatic particles experience a negligible net change in magnetic moment. We examine the robustness of such a quasi-adiabatic behavior in the presence of a large surging electric field induced by magnetic field line reconfiguration as observed during the expansion phase of substorms. We demonstrate that, although such a short-lived electric field can lead to substantial nonadiabatic heating, quasi-adiabaticity is conserved for particles with velocities larger than the peak ExB drift speed. Because of the time-varying character of the magnetic field, it is not possible to use the adiabaticity parameter κ in a straightforward manner to characterize the particle behavior. We rather consider a κ parameter that is averaged over equatorial crossings. We demonstrate that particles intercepting the field reversal in the early stage of the magnetic transition may experience significant energization and enhanced oscillating motion in the direction normal to the midplane. In contrast, particles interacting with the field reversal in the late stage of the magnetic transition experience weaker energization and slower oscillations about the midplane. We show that quasi-adiabatic particles accelerated during such events can lead to energy-time dispersion signatures at low altitudes as is observed in the plasma sheet boundary layer.
Third Sound Amplification and Detailed Balance
Eddinger, J. D.; Ellis, F. M.
2006-09-07
Condensation of atoms from the vapor into a third sound resonance is expected to be capable of acoustic amplification. This results from normal to superfluid conversion that coherently accommodates atoms into the third sound velocity field. Consideration of third sound in light of the equilibrium detailed balance between vapor particles and the superfluid film provides further evidence that acoustic amplification is attainable.
Vertical Motions Estimated Using Data from a Single Station and a Form of the Adiabatic Method.
NASA Astrophysics Data System (ADS)
Nastrom, G. D.; Warnock, J. M.
1994-01-01
The so-called adiabatic method for estimating vertical air motions under isentropic flow conditions can be used with wind and temperature data from a single station. With the advent of radio acoustic sounding systems, wind and temperature measurements will be available with the necessary frequency to employ this form of the adiabatic method on a routine basis. In an effort to test this method, data from series of Cross-chain Loran Atmospheric Sounding System balloons launched at high frequency from Champaign, Illinois, have been used to compute vertical motions. The results are compared with the synoptic setting of each campaign and with estimates made using the kinematic method. It appears that smoothing over layers about 100 hPa deep is necessary to remove features not associated with the large-scale flow. The vertical-motion results show that the adiabatic method usually compares as favorably as the kinematic method with proxy indicators of vertical motion such as clouds and moisture. The adiabatic method does not appear as reliable at the edge of cloud decks, apparently due to radiative flux divergence.
Adiabatic heating in impulsive solar flares
NASA Technical Reports Server (NTRS)
Maetzler, C.; Bai, T.; Crannell, C. J.; Frost, K. J.
1977-01-01
The dynamic X-ray spectra of two simple, impulsive solar flares are examined together with H alpha, microwave and meter wave radio observations. X-ray spectra of both events were characteristic of thermal bremsstrahlung from single temperature plasmas. The symmetry between rise and fall was found to hold for the temperature and emission measure. The relationship between temperature and emission measure was that of an adiabatic compression followed by adiabatic expansion; the adiabatic index of 5/3 indicated that the electron distribution remained isotropic. Observations in H alpha provided further evidence for compressive energy transfer.
Conditions for super-adiabatic droplet growth after entrainment mixing
Yang, Fan; Shaw, Raymond; Xue, Huiwen
2016-07-29
Cloud droplet response to entrainment and mixing between a cloud and its environment is considered, accounting for subsequent droplet growth during adiabatic ascent following a mixing event. The vertical profile for liquid water mixing ratio after a mixing event is derived analytically, allowing the reduction to be predicted from the mixing fraction and from the temperature and humidity for both the cloud and environment. It is derived for the limit of homogeneous mixing. The expression leads to a critical height above the mixing level: at the critical height the cloud droplet radius is the same for both mixed and unmixedmore » parcels, and the critical height is independent of the updraft velocity and mixing fraction. Cloud droplets in a mixed parcel are larger than in an unmixed parcel above the critical height, which we refer to as the “super-adiabatic” growth region. Analytical results are confirmed with a bin microphysics cloud model. Using the model, we explore the effects of updraft velocity, aerosol source in the environmental air, and polydisperse cloud droplets. Results show that the mixed parcel is more likely to reach the super-adiabatic growth region when the environmental air is humid and clean. It is also confirmed that the analytical predictions are matched by the volume-mean cloud droplet radius for polydisperse size distributions. The findings have implications for the origin of large cloud droplets that may contribute to onset of collision–coalescence in warm clouds.« less
Experimental demonstration of composite adiabatic passage
NASA Astrophysics Data System (ADS)
Schraft, Daniel; Halfmann, Thomas; Genov, Genko T.; Vitanov, Nikolay V.
2013-12-01
We report an experimental demonstration of composite adiabatic passage (CAP) for robust and efficient manipulation of two-level systems. The technique represents a altered version of rapid adiabatic passage (RAP), driven by composite sequences of radiation pulses with appropriately chosen phases. We implement CAP with radio-frequency pulses to invert (i.e., to rephase) optically prepared spin coherences in a Pr3+:Y2SiO5 crystal. We perform systematic investigations of the efficiency of CAP and compare the results with conventional π pulses and RAP. The data clearly demonstrate the superior features of CAP with regard to robustness and efficiency, even under conditions of weakly fulfilled adiabaticity. The experimental demonstration of composite sequences to support adiabatic passage is of significant relevance whenever a high efficiency or robustness of coherent excitation processes need to be maintained, e.g., as required in quantum information technology.
Adiabatic Quantum Search in Open Systems.
Wild, Dominik S; Gopalakrishnan, Sarang; Knap, Michael; Yao, Norman Y; Lukin, Mikhail D
2016-10-07
Adiabatic quantum algorithms represent a promising approach to universal quantum computation. In isolated systems, a key limitation to such algorithms is the presence of avoided level crossings, where gaps become extremely small. In open quantum systems, the fundamental robustness of adiabatic algorithms remains unresolved. Here, we study the dynamics near an avoided level crossing associated with the adiabatic quantum search algorithm, when the system is coupled to a generic environment. At zero temperature, we find that the algorithm remains scalable provided the noise spectral density of the environment decays sufficiently fast at low frequencies. By contrast, higher order scattering processes render the algorithm inefficient at any finite temperature regardless of the spectral density, implying that no quantum speedup can be achieved. Extensions and implications for other adiabatic quantum algorithms will be discussed.
Adiabatic Quantum Search in Open Systems
NASA Astrophysics Data System (ADS)
Wild, Dominik S.; Gopalakrishnan, Sarang; Knap, Michael; Yao, Norman Y.; Lukin, Mikhail D.
2016-10-01
Adiabatic quantum algorithms represent a promising approach to universal quantum computation. In isolated systems, a key limitation to such algorithms is the presence of avoided level crossings, where gaps become extremely small. In open quantum systems, the fundamental robustness of adiabatic algorithms remains unresolved. Here, we study the dynamics near an avoided level crossing associated with the adiabatic quantum search algorithm, when the system is coupled to a generic environment. At zero temperature, we find that the algorithm remains scalable provided the noise spectral density of the environment decays sufficiently fast at low frequencies. By contrast, higher order scattering processes render the algorithm inefficient at any finite temperature regardless of the spectral density, implying that no quantum speedup can be achieved. Extensions and implications for other adiabatic quantum algorithms will be discussed.
General conditions for quantum adiabatic evolution
Comparat, Daniel
2009-07-15
Adiabaticity occurs when, during its evolution, a physical system remains in the instantaneous eigenstate of the Hamiltonian. Unfortunately, existing results, such as the quantum adiabatic theorem based on a slow down evolution [H({epsilon}t),{epsilon}{yields}0], are insufficient to describe an evolution driven by the Hamiltonian H(t) itself. Here we derive general criteria and exact bounds, for the state and its phase, ensuring an adiabatic evolution for any Hamiltonian H(t). As a corollary, we demonstrate that the commonly used condition of a slow Hamiltonian variation rate, compared to the spectral gap, is indeed sufficient to ensure adiabaticity but only when the Hamiltonian is real and nonoscillating (for instance, containing exponential or polynomial but no sinusoidal functions)
Adiabatic limits on Riemannian Heisenberg manifolds
Yakovlev, A A
2008-02-28
An asymptotic formula is obtained for the distribution function of the spectrum of the Laplace operator, in the adiabatic limit for the foliation defined by the orbits of an invariant flow on a compact Riemannian Heisenberg manifold. Bibliography: 21 titles.
Simulation of periodically focused, adiabatic thermal beams
Chen, C.; Akylas, T. R.; Barton, T. J.; Field, D. M.; Lang, K. M.; Mok, R. V.
2012-12-21
Self-consistent particle-in-cell simulations are performed to verify earlier theoretical predictions of adiabatic thermal beams in a periodic solenoidal magnetic focusing field [K.R. Samokhvalova, J. Zhou and C. Chen, Phys. Plasma 14, 103102 (2007); J. Zhou, K.R. Samokhvalova and C. Chen, Phys. Plasma 15, 023102 (2008)]. In particular, results are obtained for adiabatic thermal beams that do not rotate in the Larmor frame. For such beams, the theoretical predictions of the rms beam envelope, the conservations of the rms thermal emittances, the adiabatic equation of state, and the Debye length are verified in the simulations. Furthermore, the adiabatic thermal beam is found be stable in the parameter regime where the simulations are performed.
AB INITIO SIMULATIONS FOR MATERIAL PROPERTIES ALONG THE JUPITER ADIABAT
French, Martin; Becker, Andreas; Lorenzen, Winfried; Nettelmann, Nadine; Bethkenhagen, Mandy; Redmer, Ronald; Wicht, Johannes
2012-09-15
We determine basic thermodynamic and transport properties of hydrogen-helium-water mixtures for the extreme conditions along Jupiter's adiabat via ab initio simulations, which are compiled in an accurate and consistent data set. In particular, we calculate the electrical and thermal conductivity, the shear and longitudinal viscosity, and diffusion coefficients of the nuclei. We present results for associated quantities like the magnetic and thermal diffusivity and the kinematic shear viscosity along an adiabat that is taken from a state-of-the-art interior structure model. Furthermore, the heat capacities, the thermal expansion coefficient, the isothermal compressibility, the Grueneisen parameter, and the speed of sound are calculated. We find that the onset of dissociation and ionization of hydrogen at about 0.9 Jupiter radii marks a region where the material properties change drastically. In the deep interior, where the electrons are degenerate, many of the material properties remain relatively constant. Our ab initio data will serve as a robust foundation for applications that require accurate knowledge of the material properties in Jupiter's interior, e.g., models for the dynamo generation.
NASA Astrophysics Data System (ADS)
Fuchs, H. V.; Möser, M.
Sound absorption indicates the transformation of sound energy into heat. It is, for instance, employed to design the acoustics in rooms. The noise emitted by machinery and plants shall be reduced before arriving at a workplace; auditoria such as lecture rooms or concert halls require a certain reverberation time. Such design goals are realised by installing absorbing components at the walls with well-defined absorption characteristics, which are adjusted for corresponding demands. Sound absorbers also play an important role in acoustic capsules, ducts and screens to avoid sound immission from noise intensive environments into the neighbourhood.
Symmetry of the Adiabatic Condition in the Piston Problem
ERIC Educational Resources Information Center
Anacleto, Joaquim; Ferreira, J. M.
2011-01-01
This study addresses a controversial issue in the adiabatic piston problem, namely that of the piston being adiabatic when it is fixed but no longer so when it can move freely. It is shown that this apparent contradiction arises from the usual definition of adiabatic condition. The issue is addressed here by requiring the adiabatic condition to be…
NASA Technical Reports Server (NTRS)
Cook, R. K.
1969-01-01
The propagation of sound waves at infrasonic frequencies (oscillation periods 1.0 - 1000 seconds) in the atmosphere is being studied by a network of seven stations separated geographically by distances of the order of thousands of kilometers. The stations measure the following characteristics of infrasonic waves: (1) the amplitude and waveform of the incident sound pressure, (2) the direction of propagation of the wave, (3) the horizontal phase velocity, and (4) the distribution of sound wave energy at various frequencies of oscillation. Some infrasonic sources which were identified and studied include the aurora borealis, tornadoes, volcanos, gravity waves on the oceans, earthquakes, and atmospheric instability waves caused by winds at the tropopause. Waves of unknown origin seem to radiate from several geographical locations, including one in the Argentine.
NASA Technical Reports Server (NTRS)
Xu, Y. J.; Khandelwal, G. S.; Wilson, John W.
1989-01-01
A simple formula for the transition probability for electron exchange between unlike ions and atoms is established within the adiabatic approximation by employing the Linear Combination of Atomic Orbitals (LCAO) method. The formula also involves an adiabatic parameter, introduced by Massey, and thus the difficulties arising from the internal energy defect and the adiabatic approximation are avoided. Specific reactions Li(+++) + H to Li(++) + H(+) and Be(4+) + H to Be(3+) + H(+) are considered as examples. The calculated capture cross section results of the present work are compared with the experimental data and with the calculation of other authors over the velocity range of 10(7) cm/sec to 10(8) cm/sec.
Inhomogeneous quasi-adiabatic driving of quantum critical dynamics in weakly disordered spin chains
NASA Astrophysics Data System (ADS)
Rams, Marek M.; Mohseni, Masoud; del Campo, Adolfo
2016-12-01
We introduce an inhomogeneous protocol to drive a weakly disordered quantum spin chain quasi-adiabatically across a quantum phase transition and minimize the residual energy of the final state. The number of spins that simultaneously reach the critical point is controlled by the length scale in which the magnetic field is modulated, introducing an effective size that favors adiabatic dynamics. The dependence of the residual energy on this length scale and the velocity at which the magnetic field sweeps out the chain is shown to be nonmonotonic. We determine the conditions for an optimal suppression of the residual energy of the final state and show that inhomogeneous driving can outperform conventional adiabatic schemes based on homogeneous control fields by several orders of magnitude.
Assessment of total efficiency in adiabatic engines
NASA Astrophysics Data System (ADS)
Mitianiec, W.
2016-09-01
The paper presents influence of ceramic coating in all surfaces of the combustion chamber of SI four-stroke engine on working parameters mainly on heat balance and total efficiency. Three cases of engine were considered: standard without ceramic coating, fully adiabatic combustion chamber and engine with different thickness of ceramic coating. Consideration of adiabatic or semi-adiabatic engine was connected with mathematical modelling of heat transfer from the cylinder gas to the cooling medium. This model takes into account changeable convection coefficient based on the experimental formulas of Woschni, heat conductivity of multi-layer walls and also small effect of radiation in SI engines. The simulation model was elaborated with full heat transfer to the cooling medium and unsteady gas flow in the engine intake and exhaust systems. The computer program taking into account 0D model of engine processes in the cylinder and 1D model of gas flow was elaborated for determination of many basic engine thermodynamic parameters for Suzuki DR-Z400S 400 cc SI engine. The paper presents calculation results of influence of the ceramic coating thickness on indicated pressure, specific fuel consumption, cooling and exhaust heat losses. Next it were presented comparisons of effective power, heat losses in the cooling and exhaust systems, total efficiency in function of engine rotational speed and also comparison of temperature inside the cylinder for standard, semi-adiabatic and full adiabatic engine. On the basis of the achieved results it was found higher total efficiency of adiabatic engines at 2500 rpm from 27% for standard engine to 37% for full adiabatic engine.
Sliding Seal Materials for Adiabatic Engines, Phase 2
NASA Technical Reports Server (NTRS)
Lankford, J.; Wei, W.
1986-01-01
An essential task in the development of the heavy-duty adiabatic diesel engine is identification and improvements of reliable, low-friction piston seal materials. In the present study, the sliding friction coefficients and wear rates of promising carbide, oxide, and nitride materials were measured under temperature, environmental, velocity, and loading conditions that are representative of the adiabatic engine environment. In addition, silicon nitride and partially stabilized zirconia disks were ion implanted with TiNi, Ni, Co, and Cr, and subsequently run against carbide pins, with the objective of producing reduced friction via solid lubrication at elevated temperature. In order to provide guidance needed to improve materials for this application, the program stressed fundamental understanding of the mechanisms involved in friction and wear. Electron microscopy was used to elucidate the micromechanisms of wear following wear testing, and Auger electron spectroscopy was used to evaluate interface/environment interactions which seemed to be important in the friction and wear process. Unmodified ceramic sliding couples were characterized at all temperatures by friction coefficients of 0.24 and above. The coefficient at 800 C in an oxidizing environment was reduced to below 0.1, for certain material combinations, by the ion implanation of TiNi or Co. This beneficial effect was found to derive from lubricious Ti, Ni, and Co oxides.
General background conditions for K-bounce and adiabaticity
NASA Astrophysics Data System (ADS)
Romano, Antonio Enea
2017-03-01
We study the background conditions for a bounce uniquely driven by a single scalar field model with a generalized kinetic term K( X), without any additional matter field. At the background level we impose the existence of two turning points where the derivative of the Hubble parameter H changes sign and of a bounce point where the Hubble parameter vanishes. We find the conditions for K( X) and the potential which ensure the above requirements. We then give the examples of two models constructed according to these conditions. One is based on a quadratic K( X), and the other on a K( X) which is avoiding divergences of the second time derivative of the scalar field, which may otherwise occur. An appropriate choice of the initial conditions can lead to a sequence of consecutive bounces, or oscillations of H. In the region where these models have a constant potential they are adiabatic on any scale and because of this they may not conserve curvature perturbations on super-horizon scales. While at the perturbation level one class of models is free from ghosts and singularities of the classical equations of motion, in general gradient instabilities are present around the bounce time, because the sign of the squared speed of sound is opposite to the sign of the time derivative of H. We discuss how this kind of instabilities could be avoided by modifying the Lagrangian by introducing Galilean terms in order to prevent a negative squared speed of sound around the bounce.
Adiabatic optimization versus diffusion Monte Carlo methods
NASA Astrophysics Data System (ADS)
Jarret, Michael; Jordan, Stephen P.; Lackey, Brad
2016-10-01
Most experimental and theoretical studies of adiabatic optimization use stoquastic Hamiltonians, whose ground states are expressible using only real nonnegative amplitudes. This raises a question as to whether classical Monte Carlo methods can simulate stoquastic adiabatic algorithms with polynomial overhead. Here we analyze diffusion Monte Carlo algorithms. We argue that, based on differences between L1 and L2 normalized states, these algorithms suffer from certain obstructions preventing them from efficiently simulating stoquastic adiabatic evolution in generality. In practice however, we obtain good performance by introducing a method that we call Substochastic Monte Carlo. In fact, our simulations are good classical optimization algorithms in their own right, competitive with the best previously known heuristic solvers for MAX-k -SAT at k =2 ,3 ,4 .
Nonadiabatic exchange dynamics during adiabatic frequency sweeps.
Barbara, Thomas M
2016-04-01
A Bloch equation analysis that includes relaxation and exchange effects during an adiabatic frequency swept pulse is presented. For a large class of sweeps, relaxation can be incorporated using simple first order perturbation theory. For anisochronous exchange, new expressions are derived for exchange augmented rotating frame relaxation. For isochronous exchange between sites with distinct relaxation rate constants outside the extreme narrowing limit, simple criteria for adiabatic exchange are derived and demonstrate that frequency sweeps commonly in use may not be adiabatic with regard to exchange unless the exchange rates are much larger than the relaxation rates. Otherwise, accurate assessment of the sensitivity to exchange dynamics will require numerical integration of the rate equations. Examples of this situation are given for experimentally relevant parameters believed to hold for in-vivo tissue. These results are of significance in the study of exchange induced contrast in magnetic resonance imaging.
... are believed to occur when air opens closed air spaces. Rales can be further described as moist, dry, fine, and coarse. Rhonchi. Sounds that resemble snoring. They occur when air is blocked or air flow becomes rough through ...
ERIC Educational Resources Information Center
Popke, Michael
2000-01-01
Discusses the planning and decision-making process in acquiring sound equipment for sports stadiums that will help make the experience of fans more pleasurable. The bidding process and use of consultants is explored. (GR)
A comparison of adiabatic and kinematic vertical motions using mesoscale data
NASA Technical Reports Server (NTRS)
Fuelberg, H. E.; Lee, W. S.
1982-01-01
Results are compared from the adiabatic and kinematic methods of determining vertical motion during a period of severe convective storms when special meso alpha-scale rawinsonde data were available. The two procedures were tested using data from the first regional-scale day of AVE-SESAME '79 which coincided with the Red River Valley tornado outbreak of April 10-11, 1979. At 700 mb, each technique showed good agreement with the weather patterns, but the kinematic procedure gave superior results at 500 mb. The overall goodness of the adiabatic method during this particular case was not solely due to the high-resolution SESAME data since synoptic-scale mechanisms played a major role in creating a storm-conducive environment. With the advent of computer aided analysis systems such as AFOS, forecasters will have quicker access to a greater variety of information. Present results suggest that the adiabatic method can yield useful information for severe storm forecasters, especially in the lower troposphere. An interesting follow-on study would use sounding data from geostationary VAS satellites to compute adiabatic vertical motions at finer time and space resolutions than is now possible using RAOB data alone. Geostrophic winds derived from satellite thermal data probably can be used.
Complexity of the Quantum Adiabatic Algorithm
NASA Technical Reports Server (NTRS)
Hen, Itay
2013-01-01
The Quantum Adiabatic Algorithm (QAA) has been proposed as a mechanism for efficiently solving optimization problems on a quantum computer. Since adiabatic computation is analog in nature and does not require the design and use of quantum gates, it can be thought of as a simpler and perhaps more profound method for performing quantum computations that might also be easier to implement experimentally. While these features have generated substantial research in QAA, to date there is still a lack of solid evidence that the algorithm can outperform classical optimization algorithms.
On adiabatic invariant in generalized Galileon theories
Ema, Yohei; Jinno, Ryusuke; Nakayama, Kazunori; Mukaida, Kyohei E-mail: jinno@hep-th.phys.s.u-tokyo.ac.jp E-mail: kazunori@hep-th.phys.s.u-tokyo.ac.jp
2015-10-01
We consider background dynamics of generalized Galileon theories in the context of inflation, where gravity and inflaton are non-minimally coupled to each other. In the inflaton oscillation regime, the Hubble parameter and energy density oscillate violently in many cases, in contrast to the Einstein gravity with minimally coupled inflaton. However, we find that there is an adiabatic invariant in the inflaton oscillation regime in any generalized Galileon theory. This adiabatic invariant is useful in estimating the expansion law of the universe and also the particle production rate due to the oscillation of the Hubble parameter.
Spontaneous emission in stimulated Raman adiabatic passage
Ivanov, P. A.; Vitanov, N. V.; Bergmann, K.
2005-11-15
This work explores the effect of spontaneous emission on the population transfer efficiency in stimulated Raman adiabatic passage (STIRAP). The approach uses adiabatic elimination of weakly coupled density matrix elements in the Liouville equation, from which a very accurate analytic approximation is derived. The loss of population transfer efficiency is found to decrease exponentially with the factor {omega}{sub 0}{sup 2}/{gamma}, where {gamma} is the spontaneous emission rate and {omega}{sub 0} is the peak Rabi frequency. The transfer efficiency increases with the pulse delay and reaches a steady value. For large pulse delay and large spontaneous emission rate STIRAP degenerates into optical pumping.
Adiabatic Hyperspherical Analysis of Realistic Nuclear Potentials
NASA Astrophysics Data System (ADS)
Daily, K. M.; Kievsky, Alejandro; Greene, Chris H.
2015-12-01
Using the hyperspherical adiabatic method with the realistic nuclear potentials Argonne V14, Argonne V18, and Argonne V18 with the Urbana IX three-body potential, we calculate the adiabatic potentials and the triton bound state energies. We find that a discrete variable representation with the slow variable discretization method along the hyperradial degree of freedom results in energies consistent with the literature. However, using a Laguerre basis results in missing energy, even when extrapolated to an infinite number of basis functions and channels. We do not include the isospin T = 3/2 contribution in our analysis.
Adiabatic cluster-state quantum computing
Bacon, Dave; Flammia, Steven T.
2010-09-15
Models of quantum computation (QC) are important because they change the physical requirements for achieving universal QC. For example, one-way QC requires the preparation of an entangled ''cluster'' state, followed by adaptive measurement on this state, a set of requirements which is different from the standard quantum-circuit model. Here we introduce a model based on one-way QC but without measurements (except for the final readout), instead using adiabatic deformation of a Hamiltonian whose initial ground state is the cluster state. Our results could help increase the feasibility of adiabatic schemes by using tools from one-way QC.
Markovian quantum master equation beyond adiabatic regime.
Yamaguchi, Makoto; Yuge, Tatsuro; Ogawa, Tetsuo
2017-01-01
By introducing a temporal change time scale τ_{A}(t) for the time-dependent system Hamiltonian, a general formulation of the Markovian quantum master equation is given to go well beyond the adiabatic regime. In appropriate situations, the framework is well justified even if τ_{A}(t) is faster than the decay time scale of the bath correlation function. An application to the dissipative Landau-Zener model demonstrates this general result. The findings are applicable to a wide range of fields, providing a basis for quantum control beyond the adiabatic regime.
Markovian quantum master equation beyond adiabatic regime
NASA Astrophysics Data System (ADS)
Yamaguchi, Makoto; Yuge, Tatsuro; Ogawa, Tetsuo
2017-01-01
By introducing a temporal change time scale τA(t ) for the time-dependent system Hamiltonian, a general formulation of the Markovian quantum master equation is given to go well beyond the adiabatic regime. In appropriate situations, the framework is well justified even if τA(t ) is faster than the decay time scale of the bath correlation function. An application to the dissipative Landau-Zener model demonstrates this general result. The findings are applicable to a wide range of fields, providing a basis for quantum control beyond the adiabatic regime.
Multiphoton Raman Atom Optics with Frequency-Swept Adiabatic Passage
NASA Astrophysics Data System (ADS)
Kotru, Krish; Butts, David; Kinast, Joseph; Stoner, Richard
2016-05-01
Light-pulse atom interferometry is a promising candidate for future inertial navigators, gravitational wave detectors, and measurements of fundamental physical constants. The sensitivity of this technique, however, is often limited by the small momentum separations created between interfering atom wave packets (typically ~ 2 ℏk) . We address this issue using light-pulse atom optics derived from stimulated Raman transitions and frequency-swept adiabatic rapid passage (ARP). In experiments, these Raman ARP atom optics have generated up to 30 ℏk photon recoil momenta in an acceleration-sensitive atom interferometer, thereby enhancing the phase shift per unit acceleration by a factor of 15. Since this approach forgoes evaporative cooling and velocity selection, it could enable large-area atom interferometry at higher data rates, while also lowering the atom shot-noise-limited measurement uncertainty.
NASA Technical Reports Server (NTRS)
1978-01-01
Lubrication technology originally developed for a series of NASA satellites has produced a commercial product for protecting the sound fidelity of phonograph records. Called Sound Guard, the preservative is a spray-on fluid that deposits a microscopically thin protective coating which reduces friction and prevents the hard diamond stylus from wearing away the softer vinyl material of the disc. It is marketed by the Consumer Products Division of Ball Corporation, Muncie, Indiana. The lubricant technology on which Sound Guard is based originated with NASA's Orbiting Solar Observatory (OSO), an Earth-orbiting satellite designed and built by Ball Brothers Research Corporation, Boulder, Colorado, also a division of Ball Corporation. Ball Brothers engineers found a problem early in the OSO program: known lubricants were unsuitable for use on satellite moving parts that would be exposed to the vacuum of space for several months. So the company conducted research on the properties of materials needed for long life in space and developed new lubricants. They worked successfully on seven OSO flights and attracted considerable attention among other aerospace contractors. Ball Brothers now supplies its "Vac Kote" lubricants and coatings to both aerospace and non-aerospace industries and the company has produced several hundred variations of the original technology. Ball Corporation expanded its product line to include consumer products, of which Sound Guard is one of the most recent. In addition to protecting record grooves, Sound Guard's anti-static quality also retards particle accumulation on the stylus. During comparison study by a leading U.S. electronic laboratory, a record not treated by Sound Guard had to be cleaned after 50 plays and the stylus had collected a considerable number of small vinyl particles. The Sound Guard-treated disc was still clean after 100 plays, as was its stylus.
Adiabatic Compression in a Fire Syringe.
ERIC Educational Resources Information Center
Hayn, Carl H.; Baird, Scott C.
1985-01-01
Suggests using better materials in fire syringes to obtain more effective results during demonstrations which show the elevation in temperature upon a very rapid (adiabatic) compression of air. Also describes an experiment (using ignition temperatures) which introduces students to the use of thermocouples for high temperature measurements. (DH)
Apparatus to Measure Adiabatic and Isothermal Processes.
ERIC Educational Resources Information Center
Lamb, D. W.; White, G. M.
1996-01-01
Describes a simple manual apparatus designed to serve as an effective demonstration of the differences between isothermal and adiabatic processes for the general or elementary physics student. Enables students to verify Boyle's law for slow processes and identify the departure from this law for rapid processes and can also be used to give a clear…
Adiabatic and Non-adiabatic quenches in a Spin-1 Bose Einstein Condensate
NASA Astrophysics Data System (ADS)
Boguslawski, Matthew; Hebbe Madhusudhana, Bharath; Anquez, Martin; Robbins, Bryce; Barrios, Maryrose; Hoang, Thai; Chapman, Michael
2016-05-01
A quantum phase transition (QPT) is observed in a wide range of phenomena. We have studied the dynamics of a spin-1 ferromagnetic Bose-Einstein condensate for both adiabatic and non-adiabatic quenches through a QPT. At the quantum critical point (QCP), finite size effects lead to a non-zero gap, which makes an adiabatic quench possible through the QPT. We experimentally demonstrate such a quench, which is forbidden at the mean field level. For faster quenches through the QCP, the vanishing energy gap causes the reaction timescale of the system to diverge, preventing the system from adiabatically following the ground state. We measure the temporal evolution of the spin populations for different quench speeds and determine the exponents characterizing the scaling of the onset of excitations, which are in good agreement with the predictions of Kibble-Zurek mechanism.
Fixed-point adiabatic quantum search
NASA Astrophysics Data System (ADS)
Dalzell, Alexander M.; Yoder, Theodore J.; Chuang, Isaac L.
2017-01-01
Fixed-point quantum search algorithms succeed at finding one of M target items among N total items even when the run time of the algorithm is longer than necessary. While the famous Grover's algorithm can search quadratically faster than a classical computer, it lacks the fixed-point property—the fraction of target items must be known precisely to know when to terminate the algorithm. Recently, Yoder, Low, and Chuang [Phys. Rev. Lett. 113, 210501 (2014), 10.1103/PhysRevLett.113.210501] gave an optimal gate-model search algorithm with the fixed-point property. Previously, it had been discovered by Roland and Cerf [Phys. Rev. A 65, 042308 (2002), 10.1103/PhysRevA.65.042308] that an adiabatic quantum algorithm, operating by continuously varying a Hamiltonian, can reproduce the quadratic speedup of gate-model Grover search. We ask, can an adiabatic algorithm also reproduce the fixed-point property? We show that the answer depends on what interpolation schedule is used, so as in the gate model, there are both fixed-point and non-fixed-point versions of adiabatic search, only some of which attain the quadratic quantum speedup. Guided by geometric intuition on the Bloch sphere, we rigorously justify our claims with an explicit upper bound on the error in the adiabatic approximation. We also show that the fixed-point adiabatic search algorithm can be simulated in the gate model with neither loss of the quadratic Grover speedup nor of the fixed-point property. Finally, we discuss natural uses of fixed-point algorithms such as preparation of a relatively prime state and oblivious amplitude amplification.
Adiabatic burst evaporation from bicontinuous nanoporous membranes.
Ichilmann, Sachar; Rücker, Kerstin; Haase, Markus; Enke, Dirk; Steinhart, Martin; Xue, Longjian
2015-05-28
Evaporation of volatile liquids from nanoporous media with bicontinuous morphology and pore diameters of a few 10 nm is an ubiquitous process. For example, such drying processes occur during syntheses of nanoporous materials by sol-gel chemistry or by spinodal decomposition in the presence of solvents as well as during solution impregnation of nanoporous hosts with functional guests. It is commonly assumed that drying is endothermic and driven by non-equilibrium partial pressures of the evaporating species in the gas phase. We show that nearly half of the liquid evaporates in an adiabatic mode involving burst-like liquid-to-gas conversions. During single adiabatic burst evaporation events liquid volumes of up to 10(7) μm(3) are converted to gas. The adiabatic liquid-to-gas conversions occur if air invasion fronts get unstable because of the built-up of high capillary pressures. Adiabatic evaporation bursts propagate avalanche-like through the nanopore systems until the air invasion fronts have reached new stable configurations. Adiabatic cavitation bursts thus compete with Haines jumps involving air invasion front relaxation by local liquid flow without enhanced mass transport out of the nanoporous medium and prevail if the mean pore diameter is in the range of a few 10 nm. The results reported here may help optimize membrane preparation via solvent-based approaches, solution-loading of nanopore systems with guest materials as well as routine use of nanoporous membranes with bicontinuous morphology and may contribute to better understanding of adsorption/desorption processes in nanoporous media.
Adiabatic circuits: converter for static CMOS signals
NASA Astrophysics Data System (ADS)
Fischer, J.; Amirante, E.; Bargagli-Stoffi, A.; Schmitt-Landsiedel, D.
2003-05-01
Ultra low power applications can take great advantages from adiabatic circuitry. In this technique a multiphase system is used which consists ideally of trapezoidal voltage signals. The input signals to be processed will often come from a function block realized in static CMOS. The static rectangular signals must be converted for the oscillating multiphase system of the adiabatic circuitry. This work shows how to convert the input signals to the proposed pulse form which is synchronized to the appropriate supply voltage. By means of adder structures designed for a 0.13µm technology in a 4-phase system there will be demonstrated, which additional circuits are necessary for the conversion. It must be taken into account whether the data arrive in parallel or serial form. Parallel data are all in one phase and therefore it is advantageous to use an adder structure with a proper input stage, e.g. a Carry Lookahead Adder (CLA). With a serial input stage it is possible to read and to process four signals during one cycle due to the adiabatic 4-phase system. Therefore input signals with a frequency four times higher than the adiabatic clock frequency can be used. This reduces the disadvantage of the slow clock period typical for adiabatic circuits. By means of an 8 bit Ripple Carry Adder (8 bit RCA) the serial reading will be introduced. If the word width is larger than 4 bits the word can be divided in 4 bit words which are processed in parallel. This is the most efficient way to minimize the number of input lines and pads. At the same time a high throughput is achieved.
The dynamic instability of adiabatic blast waves
NASA Technical Reports Server (NTRS)
Ryu, Dongsu; Vishniac, Ethan T.
1991-01-01
Adiabatic blastwaves, which have a total energy injected from the center E varies as t(sup q) and propagate through a preshock medium with a density rho(sub E) varies as r(sup -omega) are described by a family of similarity solutions. Previous work has shown that adiabatic blastwaves with increasing or constant postshock entropy behind the shock front are susceptible to an oscillatory instability, caused by the difference between the nature of the forces on the two sides of the dense shell behind the shock front. This instability sets in if the dense postshock layer is sufficiently thin. The stability of adiabatic blastwaves with a decreasing postshock entropy is considered. Such blastwaves, if they are decelerating, always have a region behind the shock front which is subject to convection. Some accelerating blastwaves also have such region, depending on the values of q, omega, and gamma where gamma is the adiabatic index. However, since the shock interface stabilizes dynamically induced perturbations, blastwaves become convectively unstable only if the convective zone is localized around the origin or a contact discontinuity far from the shock front. On the other hand, the contact discontinuity of accelerating blastwaves is subject to a strong Rayleigh-Taylor instability. The frequency spectra of the nonradial, normal modes of adiabatic blastwaves have been calculated. The results have been applied to the shocks propagating through supernovae envelopes. It is shown that the metal/He and He/H interfaces are strongly unstable against the Rayleigh-Taylor instability. This instability will induce mixing in supernovae envelopes. In addition the implications of this work for the evolution of planetary nebulae is discussed.
NASA Astrophysics Data System (ADS)
Lafon, Marion; Gauthier, Pascal; Masse, Laurent
2016-10-01
The High Foot (HF) campaign on the National Ignition Facility (NIF) has improved the neutron yield by an order of magnitude as compared to the implosions reported during the National Ignition Campaign (NIC) while dramatically lowering the ablation-front instability growth. However, this yield increase came at the expense of reduced fuel compression due to higher fuel adiabat. Thinner shell adiabat-shaped HF implosions have been designed to combine the ablation front stability benefits of the current HF pulses with the demonstrated high fuel compressibility of the NIC implosions and increased implosion velocity. This is accomplished by using a hybrid adiabat-shaping technique which both lowers the laser power between the first and second pulses to enhance the ablative stabilization at early times and precisely tailors the rise-to-peak drive to prevent undesired shocks from propagating in the fuel and depositing additional entropy. Ablation front growth factor spectra are generated from two-dimensional simulations with the FCI2 radiation hydrodynamics code. Linear analysis of the instability growth demonstrates that adiabat-shaped pulses provide a path to control and reduce ablation front instability growth while placing the fuel on a lower adiabat to achieve the alpha-heating-dominated regime. Adiabat-shaped pulses without picket are also investigated as a potential way to enhance the stability of the holhraum walls at early times.
NASA Astrophysics Data System (ADS)
Savoini, P.; Lembege, B.
2010-11-01
Adiabatic and nonadiabatic electrons transmitted through a supercritical perpendicular shock wave are analyzed with the help of test particle simulations based on field components issued from 2 - D full-particle simulation. A previous analysis (Savoini et al., 2005) based on 1 - D shock profile, including mainly a ramp (no apparent foot) and defined at a fixed time, has identified three distinct electron populations: adiabatic, overadiabatic, and underadiabatic, respectively, identified by μds/μus ≈ 1, >1 and <1, where μus and μds are the magnetic momenta in the upstream and downstream regions. Presently, this study is extended by investigating the impact of the time evolution of 2 - D shock front dynamics on these three populations. Analysis of individual time particle trajectories is performed and completed by statistics based on the use of different upstream velocity distributions (spherical shell of radius vshell and a Maxwellian with thermal velocity vthe). In all statistics, the three electron populations are clearly recovered. Two types of shock front nonstationarity are analyzed. First, the impact of the nonstationarity along the shock normal (due to the front self-reformation only) strongly depends on the values of vshell or vthe. For low values, the percentages of adiabatic and overadiabatic electrons are almost comparable but become anticorrelated under the filtering impact of the self-reformation; the percentage of the underadiabatic population remains almost unchanged. In contrast, for large values, this impact becomes negligible and the adiabatic population alone becomes dominant. Second, when 2 - D nonstationarity effects along the shock front (moving rippling) are fully included, all three populations are strongly diffused, leading to a larger heating; the overadiabatic population becomes largely dominant (and even larger than the adiabatic one) and mainly contributes to the energy spectrum.
NASA Astrophysics Data System (ADS)
Blake, E.
1998-01-01
Of the many geophysical remote-sensing techniques available today, a few are suitable for the water ice-rich, layered material expected at the north martian ice cap. Radio echo sounding has been used for several decades to determine ice thickness and internal structure. Selection of operating frequency is a tradeoff between signal attenuation (which typically increases with frequency and ice temperature) and resolution (which is proportional to wavelength). Antenna configuration and size will be additional considerations for a mission to Mars. Several configurations for ice-penetrating radar systems are discussed: these include orbiter-borne sounders, sounding antennas trailed by balloons and penetrators, and lander-borne systems. Lander-borne systems could include short-wave systems capable of resolving fine structure and layering in the upper meters beneath the lander. Spread-spectrum and deconvolution techniques can be used to increase the depth capability of a radar system. If soundings over several locations are available (e.g., with balloons, rovers, or panning short-wave systems), then it will be easier to resolve internal layering, variations in basal reflection coefficient (from which material properties may be inferred), and the geometry of nonhorizontal features. Sonic sounding has a long history in oil and gas exploration. It is, however, unlikely that large explosive charges, or even swept-frequency techniques such as Vibroseis, would be suitable for a Polar lander -- these systems are capable of penetrating several kilometers of material at frequencies of 10-200 Hz, but the energy required to generate the sound waves is large and potentially destructive. The use of audio-frequency and ultrasonic sound generated by piezoelectric crystals is discussed as a possible method to explore layering and fine features in the upper meters of the ice cap. Appropriate choice of transducer(s) will permit operation over a range of fixed or modulated frequencies
ERIC Educational Resources Information Center
Starkman, Neal
2007-01-01
Poor classroom acoustics are impairing students' hearing and their ability to learn. However, technology has come up with a solution: tools that focus voices in a way that minimizes intrusive ambient noise and gets to the intended receiver--not merely amplifying the sound, but also clarifying and directing it. One provider of classroom audio…
Quench propagation velocity for highly stabilized conductors
Mints, R.G. |; Ogitsu, T. |; Devred, A.
1995-05-01
Quench propagation velocity in conductors having a large amount of stabilizer outside the multifilamentary area is considered. It is shown that the current redistribution process between the multifilamentary area and the stabilizer can strongly effect the quench propagation. A criterion is derived determining the conditions under which the current redistribution process becomes significant, and a model of effective stabilizer area is suggested to describe its influence on the quench propagation velocity. As an illustration, the model is applied to calculate the adiabatic quench propagation velocity for a conductor geometry with a multifilamentary area embedded inside the stabilizer.
Quantum-Classical Correspondence of Shortcuts to Adiabaticity
NASA Astrophysics Data System (ADS)
Okuyama, Manaka; Takahashi, Kazutaka
2017-04-01
We formulate the theory of shortcuts to adiabaticity in classical mechanics. For a reference Hamiltonian, the counterdiabatic term is constructed from the dispersionless Korteweg-de Vries (KdV) hierarchy. Then the adiabatic theorem holds exactly for an arbitrary choice of time-dependent parameters. We use the Hamilton-Jacobi theory to define the generalized action. The action is independent of the history of the parameters and is directly related to the adiabatic invariant. The dispersionless KdV hierarchy is obtained from the classical limit of the KdV hierarchy for the quantum shortcuts to adiabaticity. This correspondence suggests some relation between the quantum and classical adiabatic theorems.
Adiabatic Quantum Simulation of Quantum Chemistry
NASA Astrophysics Data System (ADS)
Babbush, Ryan; Love, Peter J.; Aspuru-Guzik, Alán
2014-10-01
We show how to apply the quantum adiabatic algorithm directly to the quantum computation of molecular properties. We describe a procedure to map electronic structure Hamiltonians to 2-body qubit Hamiltonians with a small set of physically realizable couplings. By combining the Bravyi-Kitaev construction to map fermions to qubits with perturbative gadgets to reduce the Hamiltonian to 2-body, we obtain precision requirements on the coupling strengths and a number of ancilla qubits that scale polynomially in the problem size. Hence our mapping is efficient. The required set of controllable interactions includes only two types of interaction beyond the Ising interactions required to apply the quantum adiabatic algorithm to combinatorial optimization problems. Our mapping may also be of interest to chemists directly as it defines a dictionary from electronic structure to spin Hamiltonians with physical interactions.
Ramsey numbers and adiabatic quantum computing.
Gaitan, Frank; Clark, Lane
2012-01-06
The graph-theoretic Ramsey numbers are notoriously difficult to calculate. In fact, for the two-color Ramsey numbers R(m,n) with m, n≥3, only nine are currently known. We present a quantum algorithm for the computation of the Ramsey numbers R(m,n). We show how the computation of R(m,n) can be mapped to a combinatorial optimization problem whose solution can be found using adiabatic quantum evolution. We numerically simulate this adiabatic quantum algorithm and show that it correctly determines the Ramsey numbers R(3,3) and R(2,s) for 5≤s≤7. We then discuss the algorithm's experimental implementation, and close by showing that Ramsey number computation belongs to the quantum complexity class quantum Merlin Arthur.
Comment on ``Adiabatic theory for the bipolaron''
NASA Astrophysics Data System (ADS)
Smondyrev, M. A.; Devreese, J. T.
1996-05-01
Comments are given on the application of the Bogoliubov-Tyablikov approach to the bipolaron problem in a recent paper by Lakhno [Phys. Rev. B 51, 3512 (1995)]. This author believes that his model (1) is the translation-invariant adiabatic theory of bipolarons and (2) gives asymptotically exact solutions in the adiabatic limit while the other approaches are considered as either phenomenological or variational in nature. Numerical results by Lakhno are in contradiction with all other papers published on the subject because his model leads to much lower energies. Thus, the author concludes that bipolarons ``are more stable than was considered before.'' We prove that both the analytical and the numerical results presented by Lakhno are wrong.
Shortcuts to adiabaticity from linear response theory
Acconcia, Thiago V.; Bonança, Marcus V. S.; Deffner, Sebastian
2015-10-23
A shortcut to adiabaticity is a finite-time process that produces the same final state as would result from infinitely slow driving. We show that such shortcuts can be found for weak perturbations from linear response theory. Moreover, with the help of phenomenological response functions, a simple expression for the excess work is found—quantifying the nonequilibrium excitations. For two specific examples, i.e., the quantum parametric oscillator and the spin 1/2 in a time-dependent magnetic field, we show that finite-time zeros of the excess work indicate the existence of shortcuts. We finally propose a degenerate family of protocols, which facilitates shortcuts to adiabaticity for specific and very short driving times.
Shortcuts to adiabaticity from linear response theory
Acconcia, Thiago V.; Bonança, Marcus V. S.; Deffner, Sebastian
2015-10-23
A shortcut to adiabaticity is a finite-time process that produces the same final state as would result from infinitely slow driving. We show that such shortcuts can be found for weak perturbations from linear response theory. Moreover, with the help of phenomenological response functions, a simple expression for the excess work is found—quantifying the nonequilibrium excitations. For two specific examples, i.e., the quantum parametric oscillator and the spin 1/2 in a time-dependent magnetic field, we show that finite-time zeros of the excess work indicate the existence of shortcuts. We finally propose a degenerate family of protocols, which facilitates shortcuts tomore » adiabaticity for specific and very short driving times.« less
Adiabatic state preparation study of methylene
Veis, Libor Pittner, Jiří
2014-06-07
Quantum computers attract much attention as they promise to outperform their classical counterparts in solving certain type of problems. One of them with practical applications in quantum chemistry is simulation of complex quantum systems. An essential ingredient of efficient quantum simulation algorithms are initial guesses of the exact wave functions with high enough fidelity. As was proposed in Aspuru-Guzik et al. [Science 309, 1704 (2005)], the exact ground states can in principle be prepared by the adiabatic state preparation method. Here, we apply this approach to preparation of the lowest lying multireference singlet electronic state of methylene and numerically investigate preparation of this state at different molecular geometries. We then propose modifications that lead to speeding up the preparation process. Finally, we decompose the minimal adiabatic state preparation employing the direct mapping in terms of two-qubit interactions.
Fast forward to the classical adiabatic invariant
NASA Astrophysics Data System (ADS)
Jarzynski, Christopher; Deffner, Sebastian; Patra, Ayoti; Subaşı, Yiǧit
2017-03-01
We show how the classical action, an adiabatic invariant, can be preserved under nonadiabatic conditions. Specifically, for a time-dependent Hamiltonian H =p2/2 m +U (q ,t ) in one degree of freedom, and for an arbitrary choice of action I0, we construct a so-called fast-forward potential energy function VFF(q ,t ) that, when added to H , guides all trajectories with initial action I0 to end with the same value of action. We use this result to construct a local dynamical invariant J (q ,p ,t ) whose value remains constant along these trajectories. We illustrate our results with numerical simulations. Finally, we sketch how our classical results may be used to design approximate quantum shortcuts to adiabaticity.
Adiabatic invariance with first integrals of motion.
Adib, Artur B
2002-10-01
The construction of a microthermodynamic formalism for isolated systems based on the concept of adiabatic invariance is an old but seldom appreciated effort in the literature, dating back at least to P. Hertz [Ann. Phys. (Leipzig) 33, 225 (1910)]. An apparently independent extension of such formalism for systems bearing additional first integrals of motion was recently proposed by Hans H. Rugh [Phys. Rev. E 64, 055101 (2001)], establishing the concept of adiabatic invariance even in such singular cases. After some remarks in connection with the formalism pioneered by Hertz, it will be suggested that such an extension can incidentally explain the success of a dynamical method for computing the entropy of classical interacting fluids, at least in some potential applications where the presence of additional first integrals cannot be ignored.
Trapped Ion Quantum Computation by Adiabatic Passage
Feng Xuni; Wu Chunfeng; Lai, C. H.; Oh, C. H.
2008-11-07
We propose a new universal quantum computation scheme for trapped ions in thermal motion via the technique of adiabatic passage, which incorporates the advantages of both the adiabatic passage and the model of trapped ions in thermal motion. Our scheme is immune from the decoherence due to spontaneous emission from excited states as the system in our scheme evolves along a dark state. In our scheme the vibrational degrees of freedom are not required to be cooled to their ground states because they are only virtually excited. It is shown that the fidelity of the resultant gate operation is still high even when the magnitude of the effective Rabi frequency moderately deviates from the desired value.
Adiabatic quantum simulation of quantum chemistry.
Babbush, Ryan; Love, Peter J; Aspuru-Guzik, Alán
2014-10-13
We show how to apply the quantum adiabatic algorithm directly to the quantum computation of molecular properties. We describe a procedure to map electronic structure Hamiltonians to 2-body qubit Hamiltonians with a small set of physically realizable couplings. By combining the Bravyi-Kitaev construction to map fermions to qubits with perturbative gadgets to reduce the Hamiltonian to 2-body, we obtain precision requirements on the coupling strengths and a number of ancilla qubits that scale polynomially in the problem size. Hence our mapping is efficient. The required set of controllable interactions includes only two types of interaction beyond the Ising interactions required to apply the quantum adiabatic algorithm to combinatorial optimization problems. Our mapping may also be of interest to chemists directly as it defines a dictionary from electronic structure to spin Hamiltonians with physical interactions.
Multiphoton adiabatic passage for atom optics applications
Demeter, Gabor; Djotyan, Gagik P.
2009-04-15
We study the force exerted on two-level atoms by short, counterpropagating laser pulses. When the counterpropagating pulses overlap each other partially, multiphoton adiabatic processes are possible in several configurations, which amplify the force exerted on the atoms. We investigate the practical usefulness of such multiphoton adiabatic transitions for the manipulation of the atoms' mechanical state. In particular, we compare the efficiency of a pair of constant frequency, oppositely detuned laser pulses and that of a pair of frequency-chirped pulses. We also consider the case of prolonged exposure to a sequence of laser pulses for a duration that is comparable to or much larger than the spontaneous lifetime of the atoms. We use numerical methods to calculate the reduction of the force and the heating of the atomic ensemble when spontaneous emission cannot be neglected during the interaction. In addition, we derive simple approximate formulas for the force and the heating, and compare them to the numerical results.
Adiabatic quantum optimization for associative memory recall
Seddiqi, Hadayat; Humble, Travis S.
2014-12-22
Hopfield networks are a variant of associative memory that recall patterns stored in the couplings of an Ising model. Stored memories are conventionally accessed as fixed points in the network dynamics that correspond to energetic minima of the spin state. We show that memories stored in a Hopfield network may also be recalled by energy minimization using adiabatic quantum optimization (AQO). Numerical simulations of the underlying quantum dynamics allow us to quantify AQO recall accuracy with respect to the number of stored memories and noise in the input key. We investigate AQO performance with respect to how memories are storedmore » in the Ising model according to different learning rules. Our results demonstrate that AQO recall accuracy varies strongly with learning rule, a behavior that is attributed to differences in energy landscapes. Consequently, learning rules offer a family of methods for programming adiabatic quantum optimization that we expect to be useful for characterizing AQO performance.« less
Adiabatic quantum optimization for associative memory recall
Seddiqi, Hadayat; Humble, Travis S.
2014-12-22
Hopfield networks are a variant of associative memory that recall patterns stored in the couplings of an Ising model. Stored memories are conventionally accessed as fixed points in the network dynamics that correspond to energetic minima of the spin state. We show that memories stored in a Hopfield network may also be recalled by energy minimization using adiabatic quantum optimization (AQO). Numerical simulations of the underlying quantum dynamics allow us to quantify AQO recall accuracy with respect to the number of stored memories and noise in the input key. We investigate AQO performance with respect to how memories are stored in the Ising model according to different learning rules. Our results demonstrate that AQO recall accuracy varies strongly with learning rule, a behavior that is attributed to differences in energy landscapes. Consequently, learning rules offer a family of methods for programming adiabatic quantum optimization that we expect to be useful for characterizing AQO performance.
Adiabatic Quantum Simulation of Quantum Chemistry
Babbush, Ryan; Love, Peter J.; Aspuru-Guzik, Alán
2014-01-01
We show how to apply the quantum adiabatic algorithm directly to the quantum computation of molecular properties. We describe a procedure to map electronic structure Hamiltonians to 2-body qubit Hamiltonians with a small set of physically realizable couplings. By combining the Bravyi-Kitaev construction to map fermions to qubits with perturbative gadgets to reduce the Hamiltonian to 2-body, we obtain precision requirements on the coupling strengths and a number of ancilla qubits that scale polynomially in the problem size. Hence our mapping is efficient. The required set of controllable interactions includes only two types of interaction beyond the Ising interactions required to apply the quantum adiabatic algorithm to combinatorial optimization problems. Our mapping may also be of interest to chemists directly as it defines a dictionary from electronic structure to spin Hamiltonians with physical interactions. PMID:25308187
Computer Code For Turbocompounded Adiabatic Diesel Engine
NASA Technical Reports Server (NTRS)
Assanis, D. N.; Heywood, J. B.
1988-01-01
Computer simulation developed to study advantages of increased exhaust enthalpy in adiabatic turbocompounded diesel engine. Subsytems of conceptual engine include compressor, reciprocator, turbocharger turbine, compounded turbine, ducting, and heat exchangers. Focus of simulation of total system is to define transfers of mass and energy, including release and transfer of heat and transfer of work in each subsystem, and relationship among subsystems. Written in FORTRAN IV.
Adiabatic charging of nickel-hydrogen batteries
NASA Technical Reports Server (NTRS)
Lurie, Chuck; Foroozan, S.; Brewer, Jeff; Jackson, Lorna
1995-01-01
Battery management during prelaunch activities has always required special attention and careful planning. The transition from nickel-cadium to nickel-hydrogen batteries, with their high self discharge rate and lower charge efficiency, as well as longer prelaunch scenarios, has made this aspect of spacecraft battery management even more challenging. The AXAF-I Program requires high battery state of charge at launch. The use of active cooling, to ensure efficient charging, was considered and proved to be difficult and expensive. Alternative approaches were evaluated. Optimized charging, in the absence of cooling, appeared promising and was investigated. Initial testing was conducted to demonstrate the feasibility of the 'Adiabatic Charging' approach. Feasibility was demonstrated and additional testing performed to provide a quantitative, parametric data base. The assumption that the battery is in an adiabatic environment during prelaunch charging is a conservative approximation because the battery will transfer some heat to its surroundings by convective air cooling. The amount is small compared to the heat dissipated during battery overcharge. Because the battery has a large thermal mass, substantial overcharge can occur before the cells get too hot to charge efficiently. The testing presented here simulates a true adiabatic environment. Accordingly the data base may be slightly conservative. The adiabatic charge methodology used in this investigation begins with stabilizing the cell at a given starting temperature. The cell is then fully insulated on all sides. Battery temperature is carefully monitored and the charge terminated when the cell temperature reaches 85 F. Charging has been evaluated with starting temperatures from 55 to 75 F.
PREFACE: Aerodynamic sound Aerodynamic sound
NASA Astrophysics Data System (ADS)
Akishita, Sadao
2010-02-01
The modern theory of aerodynamic sound originates from Lighthill's two papers in 1952 and 1954, as is well known. I have heard that Lighthill was motivated in writing the papers by the jet-noise emitted by the newly commercialized jet-engined airplanes at that time. The technology of aerodynamic sound is destined for environmental problems. Therefore the theory should always be applied to newly emerged public nuisances. This issue of Fluid Dynamics Research (FDR) reflects problems of environmental sound in present Japanese technology. The Japanese community studying aerodynamic sound has held an annual symposium since 29 years ago when the late Professor S Kotake and Professor S Kaji of Teikyo University organized the symposium. Most of the Japanese authors in this issue are members of the annual symposium. I should note the contribution of the two professors cited above in establishing the Japanese community of aerodynamic sound research. It is my pleasure to present the publication in this issue of ten papers discussed at the annual symposium. I would like to express many thanks to the Editorial Board of FDR for giving us the chance to contribute these papers. We have a review paper by T Suzuki on the study of jet noise, which continues to be important nowadays, and is expected to reform the theoretical model of generating mechanisms. Professor M S Howe and R S McGowan contribute an analytical paper, a valuable study in today's fluid dynamics research. They apply hydrodynamics to solve the compressible flow generated in the vocal cords of the human body. Experimental study continues to be the main methodology in aerodynamic sound, and it is expected to explore new horizons. H Fujita's study on the Aeolian tone provides a new viewpoint on major, longstanding sound problems. The paper by M Nishimura and T Goto on textile fabrics describes new technology for the effective reduction of bluff-body noise. The paper by T Sueki et al also reports new technology for the
Aspects of adiabatic population transfer and control
NASA Astrophysics Data System (ADS)
Demirplak, Mustafa
This thesis explores two different questions. The first question we answer is how to restore a given population transfer scenario given that it works efficiently in the adiabatic limit but fails because of lack of intensity and/or short duration. We derive a very simple algorithm to do this and apply it to both toy and realistic models. Two results emerge from this study. While the mathematical existence of the programme is certain it might not always be physically desirable. The restoration of adiabaticity is phase sensitive. The second question that is answered in this thesis is not how to invent new control paradigms, but rather what would happen to them in the presence of stochastic perturbers. We first use a phenomenological model to study the effect of stochastic dephasing on population transfer by stimulated Raman adiabatic passage. The results of this Monte Carlo calculation are qualitatively explained with a perturbation theoretical result in the dressed state basis. The reliability of our phenomenological model is questioned through a more rigorous hybrid quantal-classical simulation of controlled population transfer in HCl in Ar.
Adiabatic graph-state quantum computation
NASA Astrophysics Data System (ADS)
Antonio, B.; Markham, D.; Anders, J.
2014-11-01
Measurement-based quantum computation (MBQC) and holonomic quantum computation (HQC) are two very different computational methods. The computation in MBQC is driven by adaptive measurements executed in a particular order on a large entangled state. In contrast in HQC the system starts in the ground subspace of a Hamiltonian which is slowly changed such that a transformation occurs within the subspace. Following the approach of Bacon and Flammia, we show that any MBQC on a graph state with generalized flow (gflow) can be converted into an adiabatically driven holonomic computation, which we call adiabatic graph-state quantum computation (AGQC). We then investigate how properties of AGQC relate to the properties of MBQC, such as computational depth. We identify a trade-off that can be made between the number of adiabatic steps in AGQC and the norm of \\dot{H} as well as the degree of H, in analogy to the trade-off between the number of measurements and classical post-processing seen in MBQC. Finally the effects of performing AGQC with orderings that differ from standard MBQC are investigated.
Random matrix model of adiabatic quantum computing
Mitchell, David R.; Adami, Christoph; Lue, Waynn; Williams, Colin P.
2005-05-15
We present an analysis of the quantum adiabatic algorithm for solving hard instances of 3-SAT (an NP-complete problem) in terms of random matrix theory (RMT). We determine the global regularity of the spectral fluctuations of the instantaneous Hamiltonians encountered during the interpolation between the starting Hamiltonians and the ones whose ground states encode the solutions to the computational problems of interest. At each interpolation point, we quantify the degree of regularity of the average spectral distribution via its Brody parameter, a measure that distinguishes regular (i.e., Poissonian) from chaotic (i.e., Wigner-type) distributions of normalized nearest-neighbor spacings. We find that for hard problem instances - i.e., those having a critical ratio of clauses to variables - the spectral fluctuations typically become irregular across a contiguous region of the interpolation parameter, while the spectrum is regular for easy instances. Within the hard region, RMT may be applied to obtain a mathematical model of the probability of avoided level crossings and concomitant failure rate of the adiabatic algorithm due to nonadiabatic Landau-Zener-type transitions. Our model predicts that if the interpolation is performed at a uniform rate, the average failure rate of the quantum adiabatic algorithm, when averaged over hard problem instances, scales exponentially with increasing problem size.
Adiabatic Phase Mixing and Fast Electron Heating in Thin current Sheet
NASA Astrophysics Data System (ADS)
Che, H.; Drake, J. F.; Swisdak, M. M.; Goldstein, M. L.
2012-12-01
Using particle-in-cell simulations and kinetic theory, it's found that strong Buneman instability develop non-linearly in thin current layer form in plasma with Ω e/ω pe< 1. The Buneman instability produces strong electric field and fast phase mixing which leads to the increase of electron temperature by more than a factor of 10 in a few tens of electron gyro-periods. The resonance of wave-particles feeds waves with particle's kinetic energy and causes the growth of waves and strong trapping of electrons at a large velocity range. We discovered it is the adiabatic movement of trapped electrons produce fast phase mixing when the particle's bounce rate is much larger than the growth and decay rate of waves. The adiabatic movement effectively exchange energy between particles and waves and redistribute the energy from high velocity electrons to low energy electrons with the assistance of the non-adiabatic crossing of separatrix of electron holes. The implications of the results for reconnection are being explored.
Non-adiabatic effects in near-adiabatic mixed-field orientation and alignment
NASA Astrophysics Data System (ADS)
Maan, Anjali; Ahlawat, Dharamvir Singh; Prasad, Vinod
2016-11-01
We present a theoretical study of the impact of a pair of moderate electric fields tilted an angle with respect to one another on a molecule. As a prototype, we consider a molecule with large rotational constant (with corresponding small rotational period) and moderate dipole moment. Within rigid-rotor approximation, the time-dependent Schrodinger equation is solved using fourth-order Runge-Kutta method. We have analysed that lower rotational states are significantly influenced by variation in pulse durations, the tilt angle between the fields and also on the electric field strengths. We also suggest a control scheme of how the rotational dynamics, orientation and alignment of a molecule can be enhanced by a combination of near-adiabatic pulses in comparision to non-adiabatic or adiabatic pulses.
NASA Astrophysics Data System (ADS)
Ye, Hezhou; Yin, Yanhua; Wang, Jianfeng
2015-08-01
While commercially available computational fluid dynamic packages are employed nowadays to analyze the spraying behavior of the cold spray (CS) system and optimize the nozzle geometry design, using these packages is often prohibitive because of complex computational resource requirements and expensive copyright licenses. This paper proposes a quick and economical method for predicting the performance of the CS system, while asking for minimal computational resource. A one-dimensional adiabatic friction model with the consideration of friction was developed to calculate the critical pressure of nozzles under different expansion ratios and the gas/particle velocity at different spraying conditions. The accuracy of the critical pressure calculation was evidenced by polymeric nozzle destructive tests. The particle velocities achieved from the nozzles with different expansion ratios were measured and compared with the velocity values calculated by the model. The suggested adiabatic friction model is validated by the well-matched values between the calculated results and the experimental data.
Nebogatov, V. A.; Pastukhov, V. P.
2013-06-15
A closed set of reduced equations describing low-frequency nonlinear flute magnetohydrodynamic (MHD) convection and the resulting nondiffusive processes of particle and energy transport in a weakly collisional cylindrical plasma with an anisotropic pressure is derived. The Chew-Goldberger-Low anisotropic magnetohydrodynamics is used as the basic dynamic model, because this model is applicable to describing flute convection in a cylindrical plasma column even in the low-frequency limit. The reduced set of equations was derived using the method of adiabatic separation of fast and slow motions. It is shown that the structure of the adiabatic transformation and the corresponding velocity field are identical to those obtained earlier in the isotropic MHD model. However, the derived heat transfer equations differ drastically from the isotropic pressure model. In particular, they indicate a tendency toward maintaining different radial profiles of the longitudinal and transverse pressures.
Non-adiabatic dynamics close to conical intersections and the surface hopping perspective.
Malhado, João Pedro; Bearpark, Michael J; Hynes, James T
2014-01-01
Conical intersections play a major role in the current understanding of electronic de-excitation in polyatomic molecules, and thus in the description of photochemistry and photophysics of molecular systems. This article reviews aspects of the basic theory underlying the description of non-adiabatic transitions at conical intersections, with particular emphasis on the important case when the dynamics of the nuclei are treated classically. Within this classical nuclear motion framework, the main aspects of the surface hopping methodology in the conical intersection context are presented. The emerging picture from this treatment is that of electronic transitions around conical intersections dominated by the interplay of the nuclear velocity and the derivative non-adiabatic coupling vector field.
Non-adiabatic dynamics close to conical intersections and the surface hopping perspective
Malhado, João Pedro; Bearpark, Michael J.; Hynes, James T.
2014-01-01
Conical intersections play a major role in the current understanding of electronic de-excitation in polyatomic molecules, and thus in the description of photochemistry and photophysics of molecular systems. This article reviews aspects of the basic theory underlying the description of non-adiabatic transitions at conical intersections, with particular emphasis on the important case when the dynamics of the nuclei are treated classically. Within this classical nuclear motion framework, the main aspects of the surface hopping methodology in the conical intersection context are presented. The emerging picture from this treatment is that of electronic transitions around conical intersections dominated by the interplay of the nuclear velocity and the derivative non-adiabatic coupling vector field. PMID:25485263
Effect of axial temperature gradient on chromatographic efficiency under adiabatic conditions.
Horváth, Krisztián; Horváth, Szabolcs; Lukács, Diána
2017-02-03
The effect of axial temperature gradient on the chromatographic efficiency was studied under adiabatic conditions by a modeling approach. The equilibrium-dispersive model of chromatography was used for the calculations. The model was extended by taking into account the axial temperature gradient. The results show that due to the temperature gradient, there are retention and migration velocity gradients in the column. Since the retention factor, k, is not constant in the column, k cannot be calculated as the ratio of net retention and hold-up times. As a result of the gradual increase of migration velocity, the retention times of solutes decrease as the slope of temperature gradient increases. In addition, the band in the column have extra broadening due to larger migration velocity of the front of band. The width of bands becomes larger at larger change of temperature. In the same time, however, the release velocity of the compounds from the column is increasing as ΔT increases. Accordingly, an apparent peak compression effect makes the peaks thinner. As a result of the two counteracting effects (peak expansion, apparent peak compression) the column efficiency does not change significantly in case of axial temperature gradient under adiabatic conditions. The resolutions, however, decrease slightly due to the decrease of retention times.
Bond selective chemistry beyond the adiabatic approximation
Butler, L.J.
1993-12-01
One of the most important challenges in chemistry is to develop predictive ability for the branching between energetically allowed chemical reaction pathways. Such predictive capability, coupled with a fundamental understanding of the important molecular interactions, is essential to the development and utilization of new fuels and the design of efficient combustion processes. Existing transition state and exact quantum theories successfully predict the branching between available product channels for systems in which each reaction coordinate can be adequately described by different paths along a single adiabatic potential energy surface. In particular, unimolecular dissociation following thermal, infrared multiphoton, or overtone excitation in the ground state yields a branching between energetically allowed product channels which can be successfully predicted by the application of statistical theories, i.e. the weakest bond breaks. (The predictions are particularly good for competing reactions in which when there is no saddle point along the reaction coordinates, as in simple bond fission reactions.) The predicted lack of bond selectivity results from the assumption of rapid internal vibrational energy redistribution and the implicit use of a single adiabatic Born-Oppenheimer potential energy surface for the reaction. However, the adiabatic approximation is not valid for the reaction of a wide variety of energetic materials and organic fuels; coupling between the electronic states of the reacting species play a a key role in determining the selectivity of the chemical reactions induced. The work described below investigated the central role played by coupling between electronic states in polyatomic molecules in determining the selective branching between energetically allowed fragmentation pathways in two key systems.
Anomalous Cherenkov spin-orbit sound
Smirnov, Sergey
2011-02-15
The Cherenkov effect is a well-known phenomenon in the electrodynamics of fast charged particles passing through transparent media. If the particle is faster than the light in a given medium, the medium emits a forward light cone. This beautiful phenomenon has an acoustic counterpart where the role of photons is played by phonons and the role of the speed of light is played by the sound velocity. In this case the medium emits a forward sound cone. Here, we show that in a system with spin-orbit interactions in addition to this normal Cherenkov sound there appears an anomalous Cherenkov sound with forward and backward sound propagation. Furthermore, we demonstrate that the transition from the normal to anomalous Cherenkov sound happens in a singular way at the Cherenkov cone angle. The detection of this acoustic singularity therefore represents an alternative experimental tool for the measurement of the spin-orbit coupling strength.
Quantized adiabatic transport in momentum space.
Ho, Derek Y H; Gong, Jiangbin
2012-07-06
Though topological aspects of energy bands are known to play a key role in quantum transport in solid-state systems, the implications of Floquet band topology for transport in momentum space (i.e., acceleration) have not been explored so far. Using a ratchet accelerator model inspired by existing cold-atom experiments, here we characterize a class of extended Floquet bands of one-dimensional driven quantum systems by Chern numbers, reveal topological phase transitions therein, and theoretically predict the quantization of adiabatic transport in momentum space. Numerical results confirm our theory and indicate the feasibility of experimental studies.
Adiabatic demagnetization refrigerator for space use
NASA Technical Reports Server (NTRS)
Serlemitsos, A. T.; Warner, B. A.; Castles, S.; Breon, S. R.; San Sebastian, M.; Hait, T.
1990-01-01
An Adiabatic Demagnetization Refrigerator (ADR) for space use is under development at NASA's Goddard Space Flight Center (GSFC). The breadboard ADR operated at 100 mK for 400 minutes. Some significant changes to that ADR, designed to eliminate shortcomings revealed during tests, are reported. To increase thermal contact, the ferric ammonium sulfate crystals were grown directly on gold-plated copper wires which serve as the thermal bus. The thermal link to the X-ray sensors was also markedly improved. To speed up the testing required to determine the best design parameters for the gas gap heat switch, the new heat switch has a modular design and is easy to disassemble.
Shortcuts to adiabaticity for quantum annealing
NASA Astrophysics Data System (ADS)
Takahashi, Kazutaka
2017-01-01
We study the Ising Hamiltonian with a transverse field term to simulate the quantum annealing. Using shortcuts to adiabaticity, we design the time dependence of the Hamiltonian. The dynamical invariant is obtained by the mean-field ansatz, and the Hamiltonian is designed by the inverse engineering. We show that the time dependence of physical quantities such as the magnetization is independent of the speed of the Hamiltonian variation in the infinite-range model. We also show that rotating transverse magnetic fields are useful to achieve the ideal time evolution.
Phase avalanches in near-adiabatic evolutions
Vertesi, T.; Englman, R.
2006-02-15
In the course of slow, nearly adiabatic motion of a system, relative changes in the slowness can cause abrupt and high magnitude phase changes, ''phase avalanches,'' superimposed on the ordinary geometric phases. The generality of this effect is examined for arbitrary Hamiltonians and multicomponent (>2) wave packets and is found to be connected (through the Blaschke term in the theory of analytic signals) to amplitude zeros in the lower half of the complex time plane. Motion on a nonmaximal circle on the Poincare-sphere suppresses the effect. A spectroscopic transition experiment can independently verify the phase-avalanche magnitudes.
Decoherence in a scalable adiabatic quantum computer
Ashhab, S.; Johansson, J. R.; Nori, Franco
2006-11-15
We consider the effects of decoherence on Landau-Zener crossings encountered in a large-scale adiabatic-quantum-computing setup. We analyze the dependence of the success probability--i.e., the probability for the system to end up in its new ground state--on the noise amplitude and correlation time. We determine the optimal sweep rate that is required to maximize the success probability. We then discuss the scaling of decoherence effects with increasing system size. We find that those effects can be important for large systems, even if they are small for each of the small building blocks.
Cavity-state preparation using adiabatic transfer
NASA Astrophysics Data System (ADS)
Larson, Jonas; Andersson, Erika
2005-05-01
We show how to prepare a variety of cavity field states for multiple cavities. The state preparation technique used is related to the method of stimulated adiabatic Raman passage. The cavity modes are coupled by atoms, making it possible to transfer an arbitrary cavity field state from one cavity to another and also to prepare nontrivial cavity field states. In particular, we show how to prepare entangled states of two or more cavities, such as an Einstein-Podolsky-Rosen state and a W state, as well as various entangled superpositions of coherent states in different cavities, including Schrödinger cat states. The theoretical considerations are supported by numerical simulations.
Generalized Ramsey numbers through adiabatic quantum optimization
NASA Astrophysics Data System (ADS)
Ranjbar, Mani; Macready, William G.; Clark, Lane; Gaitan, Frank
2016-09-01
Ramsey theory is an active research area in combinatorics whose central theme is the emergence of order in large disordered structures, with Ramsey numbers marking the threshold at which this order first appears. For generalized Ramsey numbers r( G, H), the emergent order is characterized by graphs G and H. In this paper we: (i) present a quantum algorithm for computing generalized Ramsey numbers by reformulating the computation as a combinatorial optimization problem which is solved using adiabatic quantum optimization; and (ii) determine the Ramsey numbers r({{T}}m,{{T}}n) for trees of order m,n = 6,7,8, most of which were previously unknown.
Generating shortcuts to adiabaticity in quantum and classical dynamics
NASA Astrophysics Data System (ADS)
Jarzynski, Christopher
2013-10-01
Transitionless quantum driving achieves adiabatic evolution in a hurry, using a counterdiabatic Hamiltonian to stifle nonadiabatic transitions. Here this shortcut to adiabaticity is cast in terms of a generator of adiabatic transport. This yields a classical analog of transitionless driving, and provides a strategy for constructing quantal counterdiabatic Hamiltonians. As an application of this framework, exact classical and quantal counterdiabatic terms are obtained for a particle in a box and for even-power-law potentials in one degree of freedom.
On the Role of Prior Probability in Adiabatic Quantum Algorithms
NASA Astrophysics Data System (ADS)
Sun, Jie; Lu, Songfeng; Yang, Liping
2016-03-01
In this paper, we study the role of prior probability on the efficiency of quantum local adiabatic search algorithm. The following aspects for prior probability are found here: firstly, only the probabilities of marked states affect the running time of the adiabatic evolution; secondly, the prior probability can be used for improving the efficiency of the adiabatic algorithm; thirdly, like the usual quantum adiabatic evolution, the running time for the case of multiple solution states where the number of marked elements are smaller enough than the size of the set assigned that contains them can be significantly bigger than that of the case where the assigned set only contains all the marked states.
Adiabatic following for a three-state quantum system
NASA Astrophysics Data System (ADS)
Huang, Wei; Shore, Bruce W.; Rangelov, Andon; Kyoseva, Elica
2017-01-01
Adiabatic time-evolution - found in various forms of adiabatic following and adiabatic passage - is often advantageous for controlled manipulation of quantum systems due to its insensitivity to deviations in the pulse shapes and timings. In this paper we discuss controlled adiabatic evolution of a three-state quantum system, a natural advance to the widespread use of two-state systems in numerous contemporary applications. We discuss, and illustrate, not only possibilities for population transfer but also for creating, with prescribed relative phase, 50:50 superpositions of two Zeeman sublevels in a letter-vee coupling linkage.
Adiabatic approximation via hodograph translation and zero-curvature equations
NASA Astrophysics Data System (ADS)
Karasev, M. V.
2014-04-01
For quantum as well classical slow-fast systems, we develop a general method which allows one to compute the adiabatic invariant (approximate integral of motion), its symmetries, the adiabatic guiding center coordinates and the effective scalar Hamiltonian in all orders of a small parameter. The scheme does not exploit eigenvectors or diagonalization, but is based on the ideas of isospectral deformation and zero-curvature equations, where the role of "time" is played by the adiabatic (quantization) parameter. The algorithm includes the construction of the zero-curvature adiabatic connection and its splitting generated by averaging up to an arbitrary order in the small parameter.
Quantum Adiabatic Algorithms and Large Spin Tunnelling
NASA Technical Reports Server (NTRS)
Boulatov, A.; Smelyanskiy, V. N.
2003-01-01
We provide a theoretical study of the quantum adiabatic evolution algorithm with different evolution paths proposed in this paper. The algorithm is applied to a random binary optimization problem (a version of the 3-Satisfiability problem) where the n-bit cost function is symmetric with respect to the permutation of individual bits. The evolution paths are produced, using the generic control Hamiltonians H (r) that preserve the bit symmetry of the underlying optimization problem. In the case where the ground state of H(0) coincides with the totally-symmetric state of an n-qubit system the algorithm dynamics is completely described in terms of the motion of a spin-n/2. We show that different control Hamiltonians can be parameterized by a set of independent parameters that are expansion coefficients of H (r) in a certain universal set of operators. Only one of these operators can be responsible for avoiding the tunnelling in the spin-n/2 system during the quantum adiabatic algorithm. We show that it is possible to select a coefficient for this operator that guarantees a polynomial complexity of the algorithm for all problem instances. We show that a successful evolution path of the algorithm always corresponds to the trajectory of a classical spin-n/2 and provide a complete characterization of such paths.
The genesis of adiabatic shear bands
Landau, P.; Osovski, S.; Venkert, A.; Gärtnerová, V.; Rittel, D.
2016-01-01
Adiabatic shear banding (ASB) is a unique dynamic failure mechanism that results in an unpredicted catastrophic failure due to a concentrated shear deformation mode. It is universally considered as a material or structural instability and as such, ASB is hardly controllable or predictable to some extent. ASB is modeled on the premise of stability analyses. The leading paradigm is that a competition between strain (rate) hardening and thermal softening determines the onset of the failure. It was recently shown that microstructural softening transformations, such as dynamic recrystallization, are responsible for adiabatic shear failure. These are dictated by the stored energy of cold work, so that energy considerations can be used to macroscopically model the failure mechanism. The initial mechanisms that lead to final failure are still unknown, as well as the ASB formation mechanism(s). Most of all - is ASB an abrupt instability or rather a gradual transition as would be dictated by microstructural evolutions? This paper reports thorough microstructural characterizations that clearly show the gradual character of the phenomenon, best described as a nucleation and growth failure mechanism, and not as an abrupt instability as previously thought. These observations are coupled to a simple numerical model that illustrates them. PMID:27849023
Accurate Variational Description of Adiabatic Quantum Optimization
NASA Astrophysics Data System (ADS)
Carleo, Giuseppe; Bauer, Bela; Troyer, Matthias
Adiabatic quantum optimization (AQO) is a quantum computing protocol where a system is driven by a time-dependent Hamiltonian. The initial Hamiltonian has an easily prepared ground-state and the final Hamiltonian encodes some desired optimization problem. An adiabatic time evolution then yields a solution to the optimization problem. Several challenges emerge in the theoretical description of this protocol: on one hand, the exact simulation of quantum dynamics is exponentially complex in the size of the optimization problem. On the other hand, approximate approaches such as tensor network states (TNS) are limited to small instances by the amount of entanglement that can be encoded. I will present here an extension of the time-dependent Variational Monte Carlo approach to problems in AQO. This approach is based on a general class of (Jastrow-Feenberg) entangled states, whose parameters are evolved in time according to a stochastic variational principle. We demonstrate this approach for optimization problems of the Ising spin-glass type. A very good accuracy is achieved when compared to exact time-dependent TNS on small instances. We then apply this approach to larger problems, and discuss the efficiency of the quantum annealing scheme in comparison with its classical counterpart.
Nonadiabatic Transitions in Adiabatic Rapid Passage
NASA Astrophysics Data System (ADS)
Lu, T.; Miao, X.; Metcalf, H.
2006-05-01
Optical forces much larger than the ordinary radiative force can be achieved on a two-level atom by multiple repetitions of adiabatic rapid passage sweeps with counterpropagating light beams. Chirped light pulses drive the atom-laser system up a ladder of dressed state energy sheets on sequential trajectories, thereby decreasing the atomic kinetic energy. Nonadiabatic transitions between the energy sheets must be avoided for this process to be effective. We have calculated the nonadiabatic transition probability for various chirped light pulses numerically. These results were compared to the first Demkov-Kunike model and the well-known Landau-Zener model. In addition, an analytical form of the nonadiabatic transition probability has been found for linearly chirped pulses and an approximate form for generic symmetric finite-time pulses has been found for the entire parameter space using the technique of unitary integration. From this, the asymptotic transition probability in the adiabatic limit was derived. T. Lu, X. Miao, and H. Metcalf, Phys., Rev. A 71 061405(R) (2005). Yu. Demkov and M. Kunike, Vestn. Leningr. Univ. Fis. Khim., 16, 39 (1969); K.-A. Suominen and B. Garraway, Phys. Rev. A45, 374 (1992)
The formation of multiple adiabatic shear bands
NASA Astrophysics Data System (ADS)
Zhou, F.; Wright, T. W.; Ramesh, K. T.
2006-07-01
In a previous paper, Zhou et al. [2006. A numerical methodology for investigating adiabatic shear band formation. J. Mech. Phys. Solids, 54, 904-926] developed a numerical method for analyzing one-dimensional deformation of thermoviscoplastic materials. The method uses a second order algorithm for integration along characteristic lines, and computes the plastic flow after complete localization with high resolution and efficiency. We apply this numerical scheme to analyze localization in a thermoviscoplastic material where multiple shear bands are allowed to form at random locations in a large specimen. As a shear band develops, it unloads neighboring regions and interacts with other bands. Beginning with a random distribution of imperfections, which might be imagined as arising qualitatively from the microstructure, we obtain the average spacing of shear bands through calculations and compare our results with previously existing theoretical estimates. It is found that the spacing between nucleating shear bands follows the perturbation theory due to Wright and Ockendon [1996. A scaling law for the effect of inertia on the formation of adiabatic shear bands. Int. J. Plasticity 12, 927-934], whereas the spacing between mature shear bands is closer to that predicted by the momentum diffusion theory of Grady and Kipp [1987. The growth of unstable thermoplastic shear with application to steady-wave shock compression in solids. J. Mech. Phys. Solids 35, 95-119]. Scaling laws for the dependence of band spacing on material parameters differ in many respects from either theory.
Adiabatic cooling of solar wind electrons
NASA Technical Reports Server (NTRS)
Sandbaek, Ornulf; Leer, Egil
1992-01-01
In thermally driven winds emanating from regions in the solar corona with base electron densities of n0 not less than 10 exp 8/cu cm, a substantial fraction of the heat conductive flux from the base is transfered into flow energy by the pressure gradient force. The adiabatic cooling of the electrons causes the electron temperature profile to fall off more rapidly than in heat conduction dominated flows. Alfven waves of solar origin, accelerating the basically thermally driven solar wind, lead to an increased mass flux and enhanced adiabatic cooling. The reduction in electron temperature may be significant also in the subsonic region of the flow and lead to a moderate increase of solar wind mass flux with increasing Alfven wave amplitude. In the solar wind model presented here the Alfven wave energy flux per unit mass is larger than that in models where the temperature in the subsonic flow is not reduced by the wave, and consequently the asymptotic flow speed is higher.
Non-adiabatic Rayleigh-Taylor instability
NASA Astrophysics Data System (ADS)
Canfield, Jesse; Denissen, Nicholas; Reisner, Jon
2016-11-01
Onset of Rayleigh-Taylor instability (RTI) in a non-adiabatic environment is investigated with the multi-physics numerical model, FLAG. This work was inspired by laboratory experiments of non-adiabatic RTI, where a glass vessel with a layer of tetrahyrdofuran (THF) below a layer of toluene was placed inside a microwave. THF, a polar solvent, readily absorbs electromagnetic energy from microwaves. Toluene, a non-polar solvent, is nearly transparent to microwave heating. The presence of a heat source in the THF layer produced convection and a time-dependent Atwood number (At). The system, initially in stable hydrostatic equilibrium At < 0 , was set into motion by microwave induced, volumetric heating of the THF. The point when At > 0 , indicates that the system is RTI unstable. The observed dominant mode at the onset of RTI was the horizontal length scale of the vessel. This scale is contrary to classical RTI, where the modes start small and increases in scale with time. It is shown that the dominant RTI mode observed in the experiments was determined by the THF length scale prior to RTI. The dominant length scale transitions from the THF to the toluene via the updrafts and downdrafts in the convective cells. This happens when At passes from negative to positive. This work was funded by the Advanced Simulation and Computing Program.
Miner, Nadine E.; Caudell, Thomas P.
2004-06-08
A sound synthesis method for modeling and synthesizing dynamic, parameterized sounds. The sound synthesis method yields perceptually convincing sounds and provides flexibility through model parameterization. By manipulating model parameters, a variety of related, but perceptually different sounds can be generated. The result is subtle changes in sounds, in addition to synthesis of a variety of sounds, all from a small set of models. The sound models can change dynamically according to changes in the simulation environment. The method is applicable to both stochastic (impulse-based) and non-stochastic (pitched) sounds.
NASA Astrophysics Data System (ADS)
Tanjia, Fatema; Mamun, A. A.
2009-02-01
A dusty plasma consisting of negatively charged cold dust, adiabatic hot ions, and inertia-less adiabatic hot electrons has been considered. The adiabatic effects of electrons and ions on the basic properties of electro-acoustic solitary waves associated with different types of electro-acoustic (viz. ion-acoustic (IA), dust ion-acoustic (DIA), and dust acoustic (DA)) waves are thoroughly investigated by the reductive perturbation method. It is found that the basic properties of the IA, DIA, and DA waves are significantly modified by the adiabatic effects of ions and inertia-less electrons. The implications of our results in space and laboratory dusty plasmas are briefly discussed.
Adiabatic contraction revisited: Implications for primordial black holes
NASA Astrophysics Data System (ADS)
Capela, Fabio; Pshirkov, Maxim; Tinyakov, Peter
2014-10-01
We simulate the adiabatic contraction of a dark matter (DM) distribution during the process of the star formation, paying particular attention to the phase space distribution of the DM particles after the contraction. Assuming the initial uniform density and Maxwellian distribution of DM velocities, we find that the number n(r) of DM particles within the radius r scales like n(r)∝r1.5, leading to the DM density profile ρ∝r-1.5, in agreement with the Liouville theorem and previous numerical studies. At the same time, the number of DM particles ν(r) with periastra smaller than r is parametrically larger, ν(r)∝r, implying that many particles contributing at any given moment into the density ρ(r) at small r have very elongated orbits and spend most of their time at distances larger than r. This has implications for the capture of DM by stars in the process of their formation. As a concrete example we consider the case of primordial black holes (PBHs). We show that accounting for very eccentric orbits boosts the amount of captured PBH by a factor of up to 2×103 depending on the PBH mass, improving correspondingly the previously derived constraints on the PBH abundance.
Bending sound in graphene: Origin and manifestation
NASA Astrophysics Data System (ADS)
Adamyan, V. M.; Bondarev, V. N.; Zavalniuk, V. V.
2016-11-01
It is proved that the acoustic-type dispersion of bending mode in graphene is generated by the fluctuation interaction between in-plane and out-of-plane terms in the free energy arising with account of non-linear components in the graphene strain tensor. In doing so we use an original adiabatic approximation based on the alleged (confirmed a posteriori) significant difference of sound speeds for in-plane and bending modes. The explicit expression for the bending sound speed depending only on the graphene mass density, in-plane elastic constants and temperature is deduced as well as the characteristics of the microscopic corrugations of graphene. The obtained results are in good quantitative agreement with the data of real experiments and computer simulations.
Transition from adiabatic inspiral to plunge into a spinning black hole
Kesden, Michael
2011-05-15
A test particle of mass {mu} on a bound geodesic of a Kerr black hole of mass M>>{mu} will slowly inspiral as gravitational radiation extracts energy and angular momentum from its orbit. This inspiral can be considered adiabatic when the orbital period is much shorter than the time scale on which energy is radiated, and quasicircular when the radial velocity is much less than the azimuthal velocity. Although the inspiral always remains adiabatic provided {mu}<
A Modified Adiabatic Quantum Algorithm for Evaluation of Boolean Functions
NASA Astrophysics Data System (ADS)
Sun, Jie; Lu, Songfeng; Liu, Fang
2015-09-01
In this paper, we propose a modified construction of the quantum adiabatic algorithm for Boolean functions studied by M. Andrecut et al. [13, 14]. Our algorithm has the time complexity O(1) for the evaluation of Boolean functions, without additional computational cost of implementing the driving Hamiltonian, which is required by the adiabatic evolution described in [13, 14].
The Adiabatic Invariance of the Action Variable in Classical Dynamics
ERIC Educational Resources Information Center
Wells, Clive G.; Siklos, Stephen T. C.
2007-01-01
We consider one-dimensional classical time-dependent Hamiltonian systems with quasi-periodic orbits. It is well known that such systems possess an adiabatic invariant which coincides with the action variable of the Hamiltonian formalism. We present a new proof of the adiabatic invariance of this quantity and illustrate our arguments by means of…
NASA Astrophysics Data System (ADS)
Gaspari, M.; Churazov, E.; Nagai, D.; Lau, E. T.; Zhuravleva, I.
2014-09-01
Exploring the power spectrum of fluctuations and velocities in the intracluster medium (ICM) can help us to probe the gas physics of galaxy clusters. Using high-resolution 3D plasma simulations, we study the statistics of the velocity field and its intimate relation with the ICM thermodynamic perturbations. The normalization of the ICM spectrum (related to density, entropy, or pressure fluctuations) is linearly tied to the level of large-scale motions, which excite both gravity and sound waves due to stratification. For a low 3D Mach number M ~ 0.25, gravity waves mainly drive entropy perturbations, which are traced by preferentially tangential turbulence. For M> 0.5, sound waves start to significantly contribute and pass the leading role to compressive pressure fluctuations, which are associated with isotropic (or slightly radial) turbulence. Density and temperature fluctuations are then characterized by the dominant process: isobaric (low M), adiabatic (high M), or isothermal (strong conduction). Most clusters reside in the intermediate regime, showing a mixture of gravity and sound waves, hence drifting toward isotropic velocities. Remarkably, regardless of the regime, the variance of density perturbations is comparable to the 1D Mach number, M1D ~ δρ/ρ. This linear relation allows us to easily convert between gas motions and ICM perturbations (δρ/ρ< 1), which can be exploited by the available Chandra, XMM data and by the forthcoming Astro-H mission. At intermediate and small scales (10-100 kpc), the turbulent velocities develop a tight Kolmogorov cascade. The thermodynamic perturbations (which can be generally described by log-normal distributions) act as effective tracers of the velocity field, in broad agreement with the Kolmogorov-Obukhov-Corrsin advection theory. The cluster radial gradients and compressive features induce a flattening in the cascade of the perturbations. Thermal conduction, on the other hand, acts to damp the thermodynamic
Large-Area Atom Interferometry with Frequency-Swept Raman Adiabatic Passage.
Kotru, Krish; Butts, David L; Kinast, Joseph M; Stoner, Richard E
2015-09-04
We demonstrate light-pulse atom interferometry with large-momentum-transfer atom optics based on stimulated Raman transitions and frequency-swept adiabatic rapid passage. Our atom optics have produced momentum splittings of up to 30 photon recoil momenta in an acceleration-sensitive interferometer for laser cooled atoms. We experimentally verify the enhancement of phase shift per unit acceleration and characterize interferometer contrast loss. By forgoing evaporative cooling and velocity selection, this method lowers the atom shot-noise-limited measurement uncertainty and enables large-area atom interferometry at higher data rates.
A wedged-peak-pulse design with medium fuel adiabat for indirect-drive fusion
Fan, Zhengfeng; Ren, Guoli; Liu, Bin; Wu, Junfeng; He, X. T.; Liu, Jie; Wang, L. F.; Ye, Wenhua
2014-10-15
In the present letter, we propose the design of a wedged-peak pulse at the late stage of indirect drive. Our simulations of one- and two-dimensional radiation hydrodynamics show that the wedged-peak-pulse design can raise the drive pressure and capsule implosion velocity without significantly raising the fuel adiabat. It can thus balance the energy requirement and hydrodynamic instability control at both ablator/fuel interface and hot-spot/fuel interface. This investigation has implication in the fusion ignition at current mega-joule laser facilities.
Chaotic jumps in the generalized first adiabatic invariant in current sheets
NASA Technical Reports Server (NTRS)
Brittnacher, M. J.; Whipple, E. C.
1991-01-01
The present study examines how the changes in the generalized first adiabatic invariant J derived from the separatrix crossing theory can be incorporated into the drift variable approach to generating distribution functions. A method is proposed for determining distribution functions for an ensemble of particles following interaction with the tail current sheet by treating the interaction as a scattering problem characterized by changes in the invariant. Generalized drift velocities are obtained for a 1D tail configuration by using the generalized first invariant. The invariant remained constant except for the discrete changes caused by chaotic scattering as the particles cross the separatrix.
Quantum Adiabatic Optimization and Combinatorial Landscapes
NASA Technical Reports Server (NTRS)
Smelyanskiy, V. N.; Knysh, S.; Morris, R. D.
2003-01-01
In this paper we analyze the performance of the Quantum Adiabatic Evolution (QAE) algorithm on a variant of Satisfiability problem for an ensemble of random graphs parametrized by the ratio of clauses to variables, gamma = M / N. We introduce a set of macroscopic parameters (landscapes) and put forward an ansatz of universality for random bit flips. We then formulate the problem of finding the smallest eigenvalue and the excitation gap as a statistical mechanics problem. We use the so-called annealing approximation with a refinement that a finite set of macroscopic variables (verses only energy) is used, and are able to show the existence of a dynamic threshold gamma = gammad, beyond which QAE should take an exponentially long time to find a solution. We compare the results for extended and simplified sets of landscapes and provide numerical evidence in support of our universality ansatz.
Number Partitioning via Quantum Adiabatic Computation
NASA Technical Reports Server (NTRS)
Smelyanskiy, Vadim N.; Toussaint, Udo; Clancy, Daniel (Technical Monitor)
2002-01-01
We study both analytically and numerically the complexity of the adiabatic quantum evolution algorithm applied to random instances of combinatorial optimization problems. We use as an example the NP-complete set partition problem and obtain an asymptotic expression for the minimal gap separating the ground and exited states of a system during the execution of the algorithm. We show that for computationally hard problem instances the size of the minimal gap scales exponentially with the problem size. This result is in qualitative agreement with the direct numerical simulation of the algorithm for small instances of the set partition problem. We describe the statistical properties of the optimization problem that are responsible for the exponential behavior of the algorithm.
The HAWC and SAFIRE Adiabatic Demagnetization Refrigerators
NASA Technical Reports Server (NTRS)
Tuttle, Jim; Shirron, Peter; DiPirro, Michael; Jackson, Michael; Behr, Jason; Kunes, Evan; Hait, Tom; Krebs, Carolyn (Technical Monitor)
2001-01-01
The High-Resolution Airborne Wide-band Camera (HAWC) and Submillimeter and Far Infrared Experiment (SAFIRE) are far-infrared experiments which will fly on the Stratospheric Observatory for Infrared Astronomy (SOFIA) aircraft. HAWC's detectors will operate at 0.2 Kelvin, while those of SAFIRE will be at 0.1 Kelvin. Each instrument will include an adiabatic demagnetization refrigerator (ADR) to cool its detector stage from the liquid helium bath temperature (HAWC's at 4.2 Kelvin and SAFIRE's pumped to about 1.3 Kelvin) to its operating temperature. Except for the magnets used to achieve the cooling and a slight difference in the heat switch design, the two ADRs are nearly identical. We describe the ADR design and present the results of performance testing.
An adiabatic demagnetization refrigerator for SIRTF
NASA Astrophysics Data System (ADS)
Timbie, P. T.; Bernstein, G. M.; Richards, P. L.
1989-02-01
An adiabatic demagnetization refrigerator (ADR) has been proposed to cool bolometric infrared detectors on the multiband imaging photometer of the Space Infrared Telescope Facility (SIRTF). One such refrigerator has been built which uses a ferric ammonium alum salt pill suspended by nylon threads in a 3-T solenoid. The resonant modes of this suspension are above 100 Hz. The heat leak to the salt pill is less than 0.5 microW. The system has a hold time at 0.1K of more than 12 h. The cold stage temperature is regulated with a feedback loop that controls the magnetic field. A second, similar refrigerator is being built at a SIRTF prototype to fly on a ballon-borne telescope. It will use a ferromagnetic shield. The possibility of using a high-Tc solenoid-actuated heat switch is also discussed.
Design of a spaceworthy adiabatic demagnetization refrigerator
NASA Astrophysics Data System (ADS)
Serlemitsos, A. T.; Kunes, E.; Sansebastian, M.
A spaceworthy adiabatic demagnetization refrigerator (ADR) under development at NASA-Goddard is presented. A baseline model heat switch was tested extensively with an on/off ratio of about 10,000 and a parasitic heat leak of 10 micro-W. Data obtained from the breadboard models were used to design an ADR with improved structural integrity. The core of the ADR is the salt pill which consists of the paramagnetic salt crystal and the thermal bus. When a magnetic field is applied to the salt it forces the alignment of the magnetic moments, thereby decreasing the entropy of the salt. Preliminary tests results showed a net crystal mass of 680 g instead of the expected 740 g, which indicate that there are gaps in the salt pill. A partial fix was accomplished by sealing helium gas in the salt pill at a pressure of 2 bar, which improved the thermal contact during salt magnetization, at about 2 K.
On stress collapse in adiabatic shear bands
NASA Astrophysics Data System (ADS)
Wright, T. W.; Walter, J. W.
T HE DYNAMICS of adiabatic shear band formation is considered making use of a simplified thermo/visco/plastic flow law. A new numerical solution is used to follow the growth of a perturbation from initiation, through early growth and severe localization, to a slowly varying terminal configuration. Asymptotic analyses predict the early and late stage patterns, but the timing and structure of the abrupt transition to severe localization can only be studied numerically, to date. A characteristic feature of the process is that temperature and plastic strain rate begin to localize immediately, but only slowly, whereas the stress first evolves almost as if there were no perturbation, but then collapses rapidly when severe localization occurs.
Index Theory and Adiabatic Limit in QFT
NASA Astrophysics Data System (ADS)
Wawrzycki, Jarosław
2013-08-01
The paper has the form of a proposal concerned with the relationship between the three mathematically rigorous approaches to quantum field theory: (1) local algebraic formulation of Haag, (2) Wightman formulation and (3) the perturbative formulation based on the microlocal renormalization method. In this project we investigate the relationship between (1) and (3) and utilize the known relationships between (1) and (2). The main goal of the proposal lies in obtaining obstructions for the existence of the adiabatic limit ( confinement problem in the phenomenological standard model approach). We extend the method of deformation of Dütsch and Fredenhagen (in the Bordeman-Waldmann sense) and apply Fedosov construction of the formal index—an analog of the index for deformed symplectic manifolds, generalizing the Atiyah-Singer index. We present some first steps in realization of the proposal.
An adiabatic demagnetization refrigerator for SIRTF
NASA Technical Reports Server (NTRS)
Timbie, P. T.; Bernstein, G. M.; Richards, P. L.
1989-01-01
An adiabatic demagnetization refrigerator (ADR) has been proposed to cool bolometric infrared detectors on the multiband imaging photometer of the Space Infrared Telescope Facility (SIRTF). One such refrigerator has been built which uses a ferric ammonium alum salt pill suspended by nylon threads in a 3-T solenoid. The resonant modes of this suspension are above 100 Hz. The heat leak to the salt pill is less than 0.5 microW. The system has a hold time at 0.1K of more than 12 h. The cold stage temperature is regulated with a feedback loop that controls the magnetic field. A second, similar refrigerator is being built at a SIRTF prototype to fly on a ballon-borne telescope. It will use a ferromagnetic shield. The possibility of using a high-Tc solenoid-actuated heat switch is also discussed.
Design of a spaceworthy adiabatic demagnetization refrigerator
NASA Technical Reports Server (NTRS)
Serlemitsos, A. T.; Kunes, E.; Sansebastian, M.
1992-01-01
A spaceworthy adiabatic demagnetization refrigerator (ADR) under development at NASA-Goddard is presented. A baseline model heat switch was tested extensively with an on/off ratio of about 10,000 and a parasitic heat leak of 10 micro-W. Data obtained from the breadboard models were used to design an ADR with improved structural integrity. The core of the ADR is the salt pill which consists of the paramagnetic salt crystal and the thermal bus. When a magnetic field is applied to the salt it forces the alignment of the magnetic moments, thereby decreasing the entropy of the salt. Preliminary tests results showed a net crystal mass of 680 g instead of the expected 740 g, which indicate that there are gaps in the salt pill. A partial fix was accomplished by sealing helium gas in the salt pill at a pressure of 2 bar, which improved the thermal contact during salt magnetization, at about 2 K.
Adiabatic connection at negative coupling strengths
Seidl, Michael; Gori-Giorgi, Paola
2010-01-15
The adiabatic connection of density functional theory (DFT) for electronic systems is generalized here to negative values of the coupling strength alpha (with attractive electrons). In the extreme limit alpha->-infinity a simple physical solution is presented and its implications for DFT (as well as its limitations) are discussed. For two-electron systems (a case in which the present solution can be calculated exactly), we find that an interpolation between the limit alpha->-infinity and the opposite limit of infinitely strong repulsion (alpha->+infinity) yields a rather accurate estimate of the second-order correlation energy E{sub c}{sup GL2}[rho] for several different densities rho, without using virtual orbitals. The same procedure is also applied to the Be isoelectronic series, analyzing the effects of near degeneracy.
Adiabatic theory for anisotropic cold molecule collisions
Pawlak, Mariusz; Shagam, Yuval; Narevicius, Edvardas; Moiseyev, Nimrod
2015-08-21
We developed an adiabatic theory for cold anisotropic collisions between slow atoms and cold molecules. It enables us to investigate the importance of the couplings between the projection states of the rotational motion of the atom about the molecular axis of the diatom. We tested our theory using the recent results from the Penning ionization reaction experiment {sup 4}He(1s2s {sup 3}S) + HD(1s{sup 2}) → {sup 4}He(1s{sup 2}) + HD{sup +}(1s) + e{sup −} [Lavert-Ofir et al., Nat. Chem. 6, 332 (2014)] and demonstrated that the couplings have strong effect on positions of shape resonances. The theory we derived provides cross sections which are in a very good agreement with the experimental findings.
An Integrated Development Environment for Adiabatic Quantum Programming
Humble, Travis S; McCaskey, Alex; Bennink, Ryan S; Billings, Jay Jay; D'Azevedo, Eduardo; Sullivan, Blair D; Klymko, Christine F; Seddiqi, Hadayat
2014-01-01
Adiabatic quantum computing is a promising route to the computational power afforded by quantum information processing. The recent availability of adiabatic hardware raises the question of how well quantum programs perform. Benchmarking behavior is challenging since the multiple steps to synthesize an adiabatic quantum program are highly tunable. We present an adiabatic quantum programming environment called JADE that provides control over all the steps taken during program development. JADE captures the workflow needed to rigorously benchmark performance while also allowing a variety of problem types, programming techniques, and processor configurations. We have also integrated JADE with a quantum simulation engine that enables program profiling using numerical calculation. The computational engine supports plug-ins for simulation methodologies tailored to various metrics and computing resources. We present the design, integration, and deployment of JADE and discuss its use for benchmarking adiabatic quantum programs.
An integrated programming and development environment for adiabatic quantum optimization
NASA Astrophysics Data System (ADS)
Humble, T. S.; McCaskey, A. J.; Bennink, R. S.; Billings, J. J.; DʼAzevedo, E. F.; Sullivan, B. D.; Klymko, C. F.; Seddiqi, H.
2014-01-01
Adiabatic quantum computing is a promising route to the computational power afforded by quantum information processing. The recent availability of adiabatic hardware has raised challenging questions about how to evaluate adiabatic quantum optimization (AQO) programs. Processor behavior depends on multiple steps to synthesize an adiabatic quantum program, which are each highly tunable. We present an integrated programming and development environment for AQO called Jade Adiabatic Development Environment (JADE) that provides control over all the steps taken during program synthesis. JADE captures the workflow needed to rigorously specify the AQO algorithm while allowing a variety of problem types, programming techniques, and processor configurations. We have also integrated JADE with a quantum simulation engine that enables program profiling using numerical calculation. The computational engine supports plug-ins for simulation methodologies tailored to various metrics and computing resources. We present the design, integration, and deployment of JADE and discuss its potential use for benchmarking AQO programs by the quantum computer science community.
Adiabatic theory, Liapunov exponents, and rotation number for quadratic Hamiltonians
NASA Astrophysics Data System (ADS)
Delyon, François; Foulon, Patrick
1987-11-01
We consider the adiabatic problem for general time-dependent quadratic Hamiltonians and develop a method quite different from WKB. In particular, we apply our results to the Schrödinger equation in a strip. We show that there exists a first regular step (avoiding resonance problems) providing one adiabatic invariant, bounds on the Liapunov exponents, and estimates on the rotation number at any order of the perturbation theory. The further step is shown to be equivalent to a quantum adiabatic problem, which, by the usual adiabatic techniques, provides the other possible adiabatic invariants. In the special case of the Schrödinger equation our method is simpler and more powerful than the WKB techniques.
Adiabatic vs. non-adiabatic determination of specific absorption rate of ferrofluids
NASA Astrophysics Data System (ADS)
Natividad, Eva; Castro, Miguel; Mediano, Arturo
2009-05-01
The measurement of temperature variations in adiabatic conditions allows the determination of the specific absorption rate of magnetic nanoparticles and ferrofluids from the correct incremental expression, SAR=(1/ m MNP) C(Δ T/Δ t). However, when measurements take place in non-adiabatic conditions, one must approximate this expression by SAR≈ Cβ/ m MNP, where β is the initial slope of the temperature vs. time curve during alternating field application. The errors arising from the use of this approximation were estimated through several experiments with different isolating conditions, temperature sensors and sample-sensor contacts. It is concluded that small to appreciable errors can appear, which are difficult to infer or control.
Non-adiabatic molecular dynamics with complex quantum trajectories. II. The adiabatic representation
Zamstein, Noa; Tannor, David J.
2012-12-14
We present a complex quantum trajectory method for treating non-adiabatic dynamics. Each trajectory evolves classically on a single electronic surface but with complex position and momentum. The equations of motion are derived directly from the time-dependent Schroedinger equation, and the population exchange arises naturally from amplitude-transfer terms. In this paper the equations of motion are derived in the adiabatic representation to complement our work in the diabatic representation [N. Zamstein and D. J. Tannor, J. Chem. Phys. 137, 22A517 (2012)]. We apply our method to two benchmark models introduced by John Tully [J. Chem. Phys. 93, 1061 (1990)], and get very good agreement with converged quantum-mechanical calculations. Specifically, we show that decoherence (spatial separation of wavepackets on different surfaces) is already contained in the equations of motion and does not require ad hoc augmentation.
Energy decomposition analysis in an adiabatic picture.
Mao, Yuezhi; Horn, Paul R; Head-Gordon, Martin
2017-02-22
Energy decomposition analysis (EDA) of electronic structure calculations has facilitated quantitative understanding of diverse intermolecular interactions. Nevertheless, such analyses are usually performed at a single geometry and thus decompose a "single-point" interaction energy. As a result, the influence of the physically meaningful EDA components on the molecular structure and other properties are not directly obtained. To address this gap, the absolutely localized molecular orbital (ALMO)-EDA is reformulated in an adiabatic picture, where the frozen, polarization, and charge transfer energy contributions are defined as energy differences between the stationary points on different potential energy surfaces (PESs), which are accessed by geometry optimizations at the frozen, polarized and fully relaxed levels of density functional theory (DFT). Other molecular properties such as vibrational frequencies can thus be obtained at the stationary points on each PES. We apply the adiabatic ALMO-EDA to different configurations of the water dimer, the water-Cl(-) and water-Mg(2+)/Ca(2+) complexes, metallocenes (Fe(2+), Ni(2+), Cu(2+), Zn(2+)), and the ammonia-borane complex. This method appears to be very useful for unraveling how physical effects such as polarization and charge transfer modulate changes in molecular properties induced by intermolecular interactions. As an example of the insight obtained, we find that a linear hydrogen bond geometry for the water dimer is preferred even without the presence of polarization and charge transfer, while the red shift in the OH stretch frequency is primarily a charge transfer effect; by contrast, a near-linear geometry for the water-chloride hydrogen bond is achieved only when charge transfer is allowed.
NASA Astrophysics Data System (ADS)
Makarov, V. A.; Petnikova, V. M.
2017-02-01
For a nonintegrable system of two coupled nonlinear Schrödinger equations the adiabatic approximation is extended for long time interaction. The method enables analytical description of the modulation of a cnoidal wave by Akhmediev breather in an isotropic nonlinear gyrotropic medium with Kerr nonlinearity and second-order group-velocity dispersion. The conditions which must be fulfilled for stable propagation of the obtained solution with amplitude and frequency modulation are determined.
Seiler, Ch.; Hogan, S. D.; Schmutz, H.; Agner, J. A.; Merkt, F.
2011-02-18
A supersonic beam of Rydberg hydrogen atoms has been adiabatically deflected by 90 deg., decelerated to zero velocity in less than 25 {mu}s, and loaded into an electric trap. The deflection has allowed the suppression of collisions with atoms in the trailing part of the gas pulse. The processes leading to trap losses, i.e., fluorescence to the ground state, and transitions and ionization induced by blackbody radiation have been monitored over several milliseconds and quantitatively analyzed.
NASA Astrophysics Data System (ADS)
Kim, Tae Hyun; Kojima, Seiji; Ko, Jae-Hyeon
2016-06-01
The acoustic properties of [011]-oriented Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystals were studied by using Brillouin spectroscopy over a wide temperature range under unpoled and poled conditions. Poling the crystal along the [011] direction induced significant changes in the sound velocity and the acoustic attenuation coefficient of both the longitudinal and the transverse acoustic modes at several characteristic temperatures. These acoustic anomalies could be attributed to changes in the polar character from macroscopic ferroelectric domains to mesoscopic polar regions along with quasi-static polar nanoregions and then to dynamic polar nanoregions upon heating the poled crystal.
Marakulin, A. O. Sazhina, O. S.; Sazhin, M. V.
2012-07-15
The possibility of the influence of adiabatic scalar perturbations on the angular velocity spectrum of extragalactic sources is considered. The multipole expansion coefficients of the angular velocity field in terms of vector spherical harmonics are calculated. We show that there is no contribution from adiabatic perturbations to the angular spectrum for a spatially flat Universe at the dusty stage, while there is a contribution only to the electric multiple coefficients at the stage of {Lambda}-term domination. The cases of long-wavelength and short-wavelength perturbations are considered separately. The relationship between the multipole angular velocity spectrum and the primordial scalar perturbation spectrum is discussed.
On the General Class of Models of Adiabatic Evolution
NASA Astrophysics Data System (ADS)
Sun, Jie; Lu, Songfeng; Liu, Fang
2016-10-01
The general class of models of adiabatic evolution was proposed to speed up the usual adiabatic computation in the case of quantum search problem. It was shown [8] that, by temporarily increasing the ground state energy of a time-dependent Hamiltonian to a suitable quantity, the quantum computation can perform the calculation in time complexity O(1). But it is also known that if the overlap between the initial and final states of the system is zero, then the computation based on the generalized models of adiabatic evolution can break down completely. In this paper, we find another severe limitation for this class of adiabatic evolution-based algorithms, which should be taken into account in applications. That is, it is still possible that this kind of evolution designed to deal with the quantum search problem fails completely if the interpolating paths in the system Hamiltonian are chosen inappropriately, while the usual adiabatic evolutions can do the same job relatively effectively. This implies that it is not always recommendable to use nonlinear paths in adiabatic computation. On the contrary, the usual simple adiabatic evolution may be sufficient for effective use.
Effects of EOS adiabat on hot spot dynamics
NASA Astrophysics Data System (ADS)
Cheng, Baolian; Kwan, Thomas; Wang, Yi-Ming; Batha, Steven
2013-10-01
Equation of state (EOS) and adiabat of the pusher play significant roles in the dynamics and formation of the hot spot of an ignition capsule. For given imploding energy, they uniquely determine the partition of internal energy, mass, and volume between the pusher and the hot spot. In this work, we apply the new scaling laws recently derived by Cheng et al. to the National Ignition Campaign (NIC) ignition capsules and study the impacts of EOS and adiabat of the pusher on the hot spot dynamics by using the EOS adiabat index as an adjustable model parameter. We compare our analysis with the NIC data, specifically, for shots N120321 and N120205, and with the numerical simulations of these shots. The predictions from our theoretical model are in good agreements with the NIC data when a hot adiabat was used for the pusher, and with code simulations when a cold adiabat was used for the pusher. Our analysis indicates that the actual adiabat of the pusher in NIC experiments may well be higher than the adiabat assumed in the simulations. This analysis provides a physical and systematic explanation to the ongoing disagreements between the NIC experimental results and the multi-dimensional numerical simulations. This work was performed under the auspices of the U.S. Department of Energy by the Los Alamos National Laboratory under contract number W-7405-ENG-36.
Non-adiabatic perturbations in Ricci dark energy model
Karwan, Khamphee; Thitapura, Thiti E-mail: nanodsci2523@hotmail.com
2012-01-01
We show that the non-adiabatic perturbations between Ricci dark energy and matter can grow both on superhorizon and subhorizon scales, and these non-adiabatic perturbations on subhorizon scales can lead to instability in this dark energy model. The rapidly growing non-adiabatic modes on subhorizon scales always occur when the equation of state parameter of dark energy starts to drop towards -1 near the end of matter era, except that the parameter α of Ricci dark energy equals to 1/2. In the case where α = 1/2, the rapidly growing non-adiabatic modes disappear when the perturbations in dark energy and matter are adiabatic initially. However, an adiabaticity between dark energy and matter perturbations at early time implies a non-adiabaticity between matter and radiation, this can influence the ordinary Sachs-Wolfe (OSW) effect. Since the amount of Ricci dark energy is not small during matter domination, the integrated Sachs-Wolfe (ISW) effect is greatly modified by density perturbations of dark energy, leading to a wrong shape of CMB power spectrum. The instability in Ricci dark energy is difficult to be alleviated if the effects of coupling between baryon and photon on dark energy perturbations are included.
NASA Astrophysics Data System (ADS)
Gösele, K.; Schröder, E.
Sound insulation between the different rooms inside a building or to the outside is a very complex problem. First, the airborne sound insulation of ceilings, walls, doors and windows is important. Second, a sufficient structure-borne sound insulation, also called impact sound insulation, for the ceilings, has to be provided especially. Finally, the service equipment should be sufficiently quiet.
Sounds Exaggerate Visual Shape
ERIC Educational Resources Information Center
Sweeny, Timothy D.; Guzman-Martinez, Emmanuel; Ortega, Laura; Grabowecky, Marcia; Suzuki, Satoru
2012-01-01
While perceiving speech, people see mouth shapes that are systematically associated with sounds. In particular, a vertically stretched mouth produces a /woo/ sound, whereas a horizontally stretched mouth produces a /wee/ sound. We demonstrate that hearing these speech sounds alters how we see aspect ratio, a basic visual feature that contributes…
ERIC Educational Resources Information Center
Merwade, Venkatesh; Eichinger, David; Harriger, Bradley; Doherty, Erin; Habben, Ryan
2014-01-01
While the science of sound can be taught by explaining the concept of sound waves and vibrations, the authors of this article focused their efforts on creating a more engaging way to teach the science of sound--through engineering design. In this article they share the experience of teaching sound to third graders through an engineering challenge…
ERIC Educational Resources Information Center
Deal, Walter F., III
2007-01-01
Sound provides and offers amazing insights into the world. Sound waves may be defined as mechanical energy that moves through air or other medium as a longitudinal wave and consists of pressure fluctuations. Humans and animals alike use sound as a means of communication and a tool for survival. Mammals, such as bats, use ultrasonic sound waves to…
Dynamics of Charged Particles in an Adiabatic Thermal Beam Equilibrium
NASA Astrophysics Data System (ADS)
Chen, Chiping; Wei, Haofei
2010-11-01
Charged-particle motion is studied in the self-electric and self-magnetic fields of a well-matched, intense charged-particle beam and an applied periodic solenoidal magnetic focusing field. The beam is assumed to be in a state of adiabatic thermal equilibrium. The phase space is analyzed and compared with that of the well-known Kapchinskij-Vladimirskij (KV)-type beam equilibrium. It is found that the widths of nonlinear resonances in the adiabatic thermal beam equilibrium are narrower than those in the KV-type beam equilibrium. Numerical evidence is presented, indicating almost complete elimination of chaotic particle motion in the adiabatic thermal beam equilibrium.
NASA Astrophysics Data System (ADS)
Denra, Raicharan; Paul, Samit; Sarkar, Susmita
2016-12-01
In this paper, characteristics of small amplitude nonlinear dust acoustic wave have been investigated in a unmagnetized, collisionless, Lorentzian dusty plasma where electrons and ions are inertialess and modeled by generalized Lorentzian Kappa distribution. Dust grains are inertial and equilibrium dust charge is negative. Both adiabatic and nonadiabatic fluctuation of charges on dust grains have been taken under consideration. For adiabatic dust charge variation reductive perturbation analysis gives rise to a KdV equation that governs the nonlinear propagation of dust acoustic waves having soliton solutions. For nonadiabatic dust charge variation nonlinear propagation of dust acoustic wave obeys KdV-Burger equation and gives rise to dust acoustic shock waves. Numerical estimation for adiabatic grain charge variation shows the existence of rarefied soliton whose amplitude and width varies with grain charges. Amplitude and width of the soliton have been plotted for different electron Kappa indices keeping ion velocity distribution Maxwellian. For non adiabatic dust charge variation, ratio of the coefficients of Burger term and dispersion term have been plotted against charge fluctuation for different kappa indices. All these results approach to the results of Maxwellian plasma if both electron and ion kappa tends to infinity.
Quantum adiabatic optimization and combinatorial landscapes
NASA Astrophysics Data System (ADS)
Smelyanskiy, V. N.; Knysh, S.; Morris, R. D.
2004-09-01
In this paper we analyze the performance of the Quantum Adiabatic Evolution algorithm on a variant of the satisfiability problem for an ensemble of random graphs parametrized by the ratio of clauses to variables, γ=M/N . We introduce a set of macroscopic parameters (landscapes) and put forward an ansatz of universality for random bit flips. We then formulate the problem of finding the smallest eigenvalue and the excitation gap as a statistical mechanics problem. We use the so-called annealing approximation with a refinement that a finite set of macroscopic variables (instead of only energy) is used, and are able to show the existence of a dynamic threshold γ=γd starting with some value of K —the number of variables in each clause. Beyond the dynamic threshold, the algorithm should take an exponentially long time to find a solution. We compare the results for extended and simplified sets of landscapes and provide numerical evidence in support of our universality ansatz. We have been able to map the ensemble of random graphs onto another ensemble with fluctuations significantly reduced. This enabled us to obtain tight upper bounds on the satisfiability transition and to recompute the dynamical transition using the extended set of landscapes.
Design of the PIXIE adiabatic demagnetization refrigerators
NASA Astrophysics Data System (ADS)
Shirron, Peter J.; Kimball, Mark O.; Fixsen, Dale J.; Kogut, Alan J.; Li, Xiaoyi; DiPirro, Michael J.
2012-04-01
The Primordial Inflation Explorer (PIXIE) is a proposed mission to densely map the polarization of the cosmic microwave background. It will operate in a scanning mode from a sun-synchronous orbit, using low temperature detectors (at 0.1 K) and located inside a telescope that is cooled to approximately 2.73 K - to match the background temperature. A mechanical cryocooler operating at 4.5 K establishes a low base temperature from which two adiabatic demagnetization refrigerator (ADR) assemblies will cool the telescope and detectors. To achieve continuous scanning capability, the ADRs must operate continuously. Complicating the design are two factors: (1) the need to systematically vary the temperature of various telescope components in order to separate the small polarization signal variations from those that may arise from temperature drifts and changing gradients within the telescope, and (2) the orbital and monthly variations in lunar irradiance into the telescope barrels. These factors require the telescope ADR to reject quasi-continuous heat loads of 2-3 mW, while maintaining a peak heat reject rate of less than 12 mW. The detector heat load at 0.1 K is comparatively small at 1-2 μW. This paper will describe the 3-stage and 2-stage continuous ADRs that will be used to meet the cooling power and temperature stability requirements of the PIXIE detectors and telescope.
Adiabatic quantum algorithm for search engine ranking.
Garnerone, Silvano; Zanardi, Paolo; Lidar, Daniel A
2012-06-08
We propose an adiabatic quantum algorithm for generating a quantum pure state encoding of the PageRank vector, the most widely used tool in ranking the relative importance of internet pages. We present extensive numerical simulations which provide evidence that this algorithm can prepare the quantum PageRank state in a time which, on average, scales polylogarithmically in the number of web pages. We argue that the main topological feature of the underlying web graph allowing for such a scaling is the out-degree distribution. The top-ranked log(n) entries of the quantum PageRank state can then be estimated with a polynomial quantum speed-up. Moreover, the quantum PageRank state can be used in "q-sampling" protocols for testing properties of distributions, which require exponentially fewer measurements than all classical schemes designed for the same task. This can be used to decide whether to run a classical update of the PageRank.
Adiabatic Quantum Algorithm for Search Engine Ranking
NASA Astrophysics Data System (ADS)
Garnerone, Silvano; Zanardi, Paolo; Lidar, Daniel A.
2012-06-01
We propose an adiabatic quantum algorithm for generating a quantum pure state encoding of the PageRank vector, the most widely used tool in ranking the relative importance of internet pages. We present extensive numerical simulations which provide evidence that this algorithm can prepare the quantum PageRank state in a time which, on average, scales polylogarithmically in the number of web pages. We argue that the main topological feature of the underlying web graph allowing for such a scaling is the out-degree distribution. The top-ranked log(n) entries of the quantum PageRank state can then be estimated with a polynomial quantum speed-up. Moreover, the quantum PageRank state can be used in “q-sampling” protocols for testing properties of distributions, which require exponentially fewer measurements than all classical schemes designed for the same task. This can be used to decide whether to run a classical update of the PageRank.
On the persistence of adiabatic shear bands
NASA Astrophysics Data System (ADS)
Boakye-Yiadom, S.; Bassim, M. N.; Al-Ameeri, S.
2012-08-01
It is generally agreed that the initiation and development of adiabatic shear bands (ASBs) are manifestations of damage in metallic materials subjected to high strain rates and large strains as those due to impact in a Hopkinson Bar system. Models for evolution of these bands have been described in the literature. One question that has not received attention is how persistent these bands are and whether their presence and effect can be reversed or eliminated by using a process of thermal (heat treatment) or thermo-mechanical treatment that would relieve the material from the high strain associated with ASBs and their role as precursors to crack initiation and subsequent failure. Since ASBs are more prevalent and more defined in BCC metals including steels, a study was conducted to investigate the best conditions of generating ASBs in a heat treatable steel, followed by determining the best conditions for heat treatment of specimens already damaged by the presence of ASBs in order to relieve the strains due to ASBs and restore the material to an apparent microstructure without the "scars" due to the previous presence of ASBs. It was found that heat treatment achieves the curing from ASBs. This presentation documents the process undertaken to achieve this objective.
Adiabatic Spin Pumping with Quantum Dots
NASA Astrophysics Data System (ADS)
Mucciolo, Eduardo R.
Electronic transport in mesoscopic systems has been intensively studied for more the last three decades. While there is a substantial understanding of the stationary regime, much less is know about phase-coherent nonequilibrium transport when pulses or ac perturbations are used to drive electrons at low temperatures and at small length scales. However, about 20 years ago Thouless proposed to drive nondissipative currents in quantum systems by applying simultaneously two phase-locked external perturbations. The so-called adiabatic pumping mechanism has been revived in the last few years, both theoretically and experimentally, in part because of the development of lateral semiconductor quantum dots. Here we will explain how open dots can be used to create spin-polarized currents with little or no net charge transfer. The pure spin pump we propose is the analog of a charge battery in conventional electronics and may provide a needed circuit element for spin-based electronics. We will also discuss other relevant issues such as rectification and decoherence and point out possible extensions of the mechanism to closed dots.
Power spectra in the eikonal approximation with adiabatic and nonadiabatic modes
NASA Astrophysics Data System (ADS)
Bernardeau, Francis; Van de Rijt, Nicolas; Vernizzi, Filippo
2013-02-01
We use the so-called eikonal approximation, recently introduced in the context of cosmological perturbation theory, to compute power spectra for multicomponent fluids. We demonstrate that, at any given order in standard perturbation theory, multipoint power spectra do not depend on the large-scale adiabatic modes. Moreover, we employ perturbation theories to decipher how nonadiabatic modes, such as a relative velocity between two different components, damp the small-scale matter power spectrum, a mechanism recently described in the literature. In particular, we do an explicit calculation at one-loop order of this effect. While the one-loop result eventually breaks down, we show how the damping effect can be fully captured by the help of the eikonal approximation. A relative velocity not only induces mode damping but also creates large-scale anisotropic modulations of the matter power spectrum amplitude. We illustrate this for the Local Group environment.
Auditory velocity discrimination in the horizontal plane at very high velocities.
Frissen, Ilja; Féron, François-Xavier; Guastavino, Catherine
2014-10-01
We determined velocity discrimination thresholds and Weber fractions for sounds revolving around the listener at very high velocities. Sounds used were a broadband white noise and two harmonic sounds with fundamental frequencies of 330 Hz and 1760 Hz. Experiment 1 used velocities ranging between 288°/s and 720°/s in an acoustically treated room and Experiment 2 used velocities between 288°/s and 576°/s in a highly reverberant hall. A third experiment addressed potential confounds in the first two experiments. The results show that people can reliably discriminate velocity at very high velocities and that both thresholds and Weber fractions decrease as velocity increases. These results violate Weber's law but are consistent with the empirical trend observed in the literature. While thresholds for the noise and 330 Hz harmonic stimulus were similar, those for the 1760 Hz harmonic stimulus were substantially higher. There were no reliable differences in velocity discrimination between the two acoustical environments, suggesting that auditory motion perception at high velocities is robust against the effects of reverberation.
Acceleration of adiabatic quantum dynamics in electromagnetic fields
Masuda, Shumpei; Nakamura, Katsuhiro
2011-10-15
We show a method to accelerate quantum adiabatic dynamics of wave functions under electromagnetic field (EMF) by developing the preceding theory [Masuda and Nakamura, Proc. R. Soc. London Ser. A 466, 1135 (2010)]. Treating the orbital dynamics of a charged particle in EMF, we derive the driving field which accelerates quantum adiabatic dynamics in order to obtain the final adiabatic states in any desired short time. The scheme is consolidated by describing a way to overcome possible singularities in both the additional phase and driving potential due to nodes proper to wave functions under EMF. As explicit examples, we exhibit the fast forward of adiabatic squeezing and transport of excited Landau states with nonzero angular momentum, obtaining the result consistent with the transitionless quantum driving applied to the orbital dynamics in EMF.
Adiabatic shear bands localization in materials undergoing deformations
NASA Astrophysics Data System (ADS)
Ryabov, P. N.; Kudryashov, N. A.; Muratov, R. V.
2017-01-01
We consider the adiabatic shear banding phenomenon in composite materials undergoing the high speed shear deformations. The mathematical model of adiabatic shear banding in thermo-visco-plastic material is given. New two step numerical algorithm which is based on the Courant-Isaacson-Rees scheme that allows one to simulate fully localized plastic flow from initial stage of localization is proposed. To test this numerical algorithm we use three benchmark problems. The testing results show the accuracy and efficiency of proposed algorithm. The features of adiabatic shear bands formation in composites are studied. The existence of characteristic depth of localization in composites is shown. Influence of initial temperature distribution on the processes of adiabatic shear bands formation in composites is considered.
Adiabaticity and spectral splits in collective neutrino transformations
Raffelt, Georg G.; Smirnov, Alexei Yu.
2007-12-15
Neutrinos streaming off a supernova core transform collectively by neutrino-neutrino interactions, leading to 'spectral splits' where an energy E{sub split} divides the transformed spectrum sharply into parts of almost pure but different flavors. We present a detailed description of the spectral-split phenomenon which is conceptually and quantitatively understood in an adiabatic treatment of neutrino-neutrino effects. Central to this theory is a self-consistency condition in the form of two sum rules (integrals over the neutrino spectra that must equal certain conserved quantities). We provide explicit analytic and numerical solutions for various neutrino spectra. We introduce the concept of the adiabatic reference frame and elaborate on the relative adiabatic evolution. Violating adiabaticity leads to the spectral split being 'washed out'. The sharpness of the split appears to be represented by a surprisingly universal function.
Adiabatic and isocurvature perturbation projections in multi-field inflation
Gordon, Chris; Saffin, Paul M. E-mail: Paul.Saffin@nottingham.ac.uk
2013-08-01
Current data are in good agreement with the predictions of single field inflation. However, the hemispherical asymmetry, seen in the cosmic microwave background data, may hint at a potential problem. Generalizing to multi-field models may provide one possible explanation. A useful way of modeling perturbations in multi-field inflation is to investigate the projection of the perturbation along and perpendicular to the background fields' trajectory. These correspond to the adiabatic and isocurvature perturbations. However, it is important to note that in general there are no corresponding adiabatic and isocurvature fields. The purpose of this article is to highlight the distinction between a field redefinition and a perturbation projection. We provide a detailed derivation of the evolution of the isocurvature perturbation to show that no assumption of an adiabatic or isocurvature field is needed. We also show how this evolution equation is consistent with the field covariant evolution equations for the adiabatic perturbation in the flat field space limit.
Ultrafast stimulated Raman parallel adiabatic passage by shaped pulses
Dridi, G.; Guerin, S.; Hakobyan, V.; Jauslin, H. R.; Eleuch, H.
2009-10-15
We present a general and versatile technique of population transfer based on parallel adiabatic passage by femtosecond shaped pulses. Their amplitude and phase are specifically designed to optimize the adiabatic passage corresponding to parallel eigenvalues at all times. We show that this technique allows the robust adiabatic population transfer in a Raman system with the total pulse area as low as 3{pi}, corresponding to a fluence of one order of magnitude below the conventional stimulated Raman adiabatic passage process. This process of short duration, typically picosecond and subpicosecond, is easily implementable with the modern pulse shaper technology and opens the possibility of ultrafast robust population transfer with interesting applications in quantum information processing.
Shortcuts to adiabaticity for non-Hermitian systems
Ibanez, S.; Martinez-Garaot, S.; Torrontegui, E.; Muga, J. G.; Chen Xi
2011-08-15
Adiabatic processes driven by non-Hermitian, time-dependent Hamiltonians may be sped up by generalizing inverse engineering techniques based on counter-diabatic (transitionless driving) algorithms or on dynamical invariants. We work out the basic theory and examples described by two-level Hamiltonians: the acceleration of rapid adiabatic passage with a decaying excited level and of the dynamics of a classical particle on an expanding harmonic oscillator.
Nonadiabatic transitions in finite-time adiabatic rapid passage
NASA Astrophysics Data System (ADS)
Lu, T.; Miao, X.; Metcalf, H.
2007-06-01
To apply the adiabatic rapid passage process repetitively [T. Lu, X. Miao, and H. Metcalf, Phys. Rev. A 71, 061405(R) (2005)], the nonadiabatic transition probability of a two-level atom subject to chirped light pulses over a finite period of time needs to be calculated. Using a unitary first-order perturbation method in the rotating adiabatic frame, an approximate formula has been derived for such transition probabilities in the entire parameter space of the pulses.
ENTROPY-VORTEX WAVES IN NON-ADIABATIC FLOWS
Ibáñez S, Miguel H.
2016-02-20
The Ertel theorem on the vorticity along the flow of adiabatic fluids is generalized for non-adiabatic flows. Several limiting cases are analyzed and the results are applied to flows behind different hydrodynamics fronts, particularly to thermal fronts (heat and cooling fronts). An important conclusion of the present analysis is that vorticity is inherent in the condensation’s (or hot spots) formation by thermal instabilities in plasma flows. Implications for several astrophysical plasmas are outlined.
Vacuum vessel eddy current modeling for TFTR adiabatic compression experiments
DeLucia, J.; Bell, M.; Wong, K.L.
1985-07-01
A relatively simple current filament model of the TFTR vacuum vessel is described. It is used to estimate the three-dimensional structure of magnetic field perturbations in the vicinity of the plasma that arise from vacuum vessel eddy currents induced during adiabatic compression. Eddy currents are calculated self-consistently with the plasma motion. The Shafranov formula and adiabatic scaling laws are used to model the plasma. Although the specific application is to TFTR, the present model is of generation applicability.
A connection between mix and adiabat in ICF capsules
NASA Astrophysics Data System (ADS)
Cheng, Baolian; Kwan, Thomas; Wang, Yi-Ming; Yi, Sunghuan (Austin); Batha, Steven
2016-10-01
We study the relationship between instability induced mix, preheat and the adiabat of the deuterium-tritium (DT) fuel in fusion capsule experiments. Our studies show that hydrodynamic instability not only directly affects the implosion, hot spot shape and mix, but also affects the thermodynamics of the capsule, such as, the adiabat of the DT fuel, and, in turn, affects the energy partition between the pusher shell (cold DT) and the hot spot. It was found that the adiabat of the DT fuel is sensitive to the amount of mix caused by Richtmyer-Meshkov (RM) and Rayleigh-Taylor (RT) instabilities at the material interfaces due to its exponential dependence on the fuel entropy. An upper limit of mix allowed maintaining a low adiabat of DT fuel is derived. Additionally we demonstrated that the use of a high adiabat for the DT fuel in theoretical analysis and with the aid of 1D code simulations could explain some aspects of the 3D effects and mix in the capsule experiments. Furthermore, from the observed neutron images and our physics model, we could infer the adiabat of the DT fuel in the capsule and determine the possible amount of mix in the hot spot (LA-UR-16-24880). This work was conducted under the auspices of the U.S. Department of Energy by the Los Alamos National Laboratory under Contract No. W-7405-ENG-36.
The speed of sound in periodic ducts
NASA Astrophysics Data System (ADS)
Russo, Serena; Fabre, David; Giannetti, Flavio; Luchini, Paolo
2016-01-01
The flow through corrugated pipes is known to lead to strong whistling tones which may be harmful in many industrial appliances. The mechanism is known to originate from a coupling between vortex shedding at the edges of the cavities forming the wall of the tube and the acoustical modes of the pipe. The latter depend upon the effective velocity of sound ceff within the corrugated pipe. The purpose of this paper is to compute accurately this effective velocity of sound through an asymptotic calculation valid in the long-wave limit. Results are given for a number of geometries used in previous works, and compared with a simple model in which the effective speed of sound is function of the geometry of the pipe. The latter is found to work best for short cavities but significant disagreement is found for longer cavities. The case of 2D channels with a corrugated wall is also considered.
Adiabatic and non-adiabatic charge pumping in a single-level molecular motor
NASA Astrophysics Data System (ADS)
Napitu, B. D.; Thijssen, J. M.
2015-07-01
We propose a design for realizing quantum charge pump based on a recent proposal for a molecular motor (Seldenthuis J S et al 2010 ACS Nano 4 6681). Our design is based on the presence of a moiety with a permanent dipole moment which can rotate, thereby modulating the couplings to metallic contacts at both ends of the molecule. Using the non-equilibrium Keldysh Green’s function formalism (NEGF), we show that our design indeed generates a pump current. In the non-interacting pump, the variation of frequency from adiabatic to non-adiabatic regime, can be used to control the direction as well as the amplitude of the average current. The effect of Coulomb interaction is considered within the first- and the second- order perturbation. The numerical implementation of the scheme is quite demanding, and we develop an analytical approximation to obtain a speed-up giving results within a reasonable time. We find that the amplitude of the average pumped current can be controlled by both the driving frequency and the Coulomb interaction. The direction of of pumped current is shown to be determined by the phase difference between left and right anchoring groups.
Adiabatic and non-adiabatic charge pumping in a single-level molecular motor.
Napitu, B D; Thijssen, J M
2015-07-15
We propose a design for realizing quantum charge pump based on a recent proposal for a molecular motor (Seldenthuis J S et al 2010 ACS Nano 4 6681). Our design is based on the presence of a moiety with a permanent dipole moment which can rotate, thereby modulating the couplings to metallic contacts at both ends of the molecule. Using the non-equilibrium Keldysh Green's function formalism (NEGF), we show that our design indeed generates a pump current. In the non-interacting pump, the variation of frequency from adiabatic to non-adiabatic regime, can be used to control the direction as well as the amplitude of the average current. The effect of Coulomb interaction is considered within the first- and the second- order perturbation. The numerical implementation of the scheme is quite demanding, and we develop an analytical approximation to obtain a speed-up giving results within a reasonable time. We find that the amplitude of the average pumped current can be controlled by both the driving frequency and the Coulomb interaction. The direction of of pumped current is shown to be determined by the phase difference between left and right anchoring groups.
Adiabatic fission barriers in superheavy nuclei
NASA Astrophysics Data System (ADS)
Jachimowicz, P.; Kowal, M.; Skalski, J.
2017-01-01
Using the microscopic-macroscopic model based on the deformed Woods-Saxon single-particle potential and the Yukawa-plus-exponential macroscopic energy, we calculated static fission barriers Bf for 1305 heavy and superheavy nuclei 98 ≤Z ≤126 , including even-even, odd-even, even-odd and odd-odd systems. For odd and odd-odd nuclei, adiabatic potential-energy surfaces were calculated by a minimization over configurations with one blocked neutron or/and proton on a level from the 10th below to the 10th above the Fermi level. The parameters of the model that have been fixed previously by a fit to masses of even-even heavy nuclei were kept unchanged. A search for saddle points has been performed by the "imaginary water flow" method on a basic five-dimensional deformation grid, including triaxiality. Two auxiliary grids were used for checking the effects of the mass asymmetry and hexadecapole nonaxiality. The ground states (g.s.) were found by energy minimization over configurations and deformations. We find that the nonaxiality significantly changes first and second fission saddle in many nuclei. The effect of the mass asymmetry, known to lower the second, very deformed saddles in actinides, in the heaviest nuclei appears at the less deformed saddles in more than 100 nuclei. It happens for those saddles in which the triaxiality does not play any role, which suggests a decoupling between effects of the mass asymmetry and triaxiality. We studied also the influence of the pairing interaction strength on the staggering of Bf for odd- and even-particle numbers. Finally, we provide a comparison of our results with other theoretical fission barrier evaluations and with available experimental estimates.
Acoustic velocity meter systems
Laenen, Antonius
1985-01-01
Acoustic velocity meter (AVM) systems operate on the principles that the point-to-point upstream traveltime of an acoustic pulse is longer than the downstream traveltime and that this difference in traveltime can be accurately measured by electronic devices. An AVM system is capable of recording water velocity (and discharge) under a wide range of conditions, but some constraints apply: 1. Accuracy is reduced and performance is degraded if the acoustic path is not a continuous straight line. The path can be bent by reflection if it is too close to a stream boundary or by refraction if it passes through density gradients resulting from variations in either water temperature or salinity. For paths of less than 100 m, a temperature gradient of 0.1' per meter causes signal bending less than 0.6 meter at midchannel, and satisfactory velocity results can be obtained. Reflection from stream boundaries can cause signal cancellation if boundaries are too close to signal path. 2. Signal strength is attenuated by particles or bubbles that absorb, spread, or scatter sound. The concentration of particles or bubbles that can be tolerated is a function of the path length and frequency of the acoustic signal. 3. Changes in streamline orientation can affect system accuracy if the variability is random. 4. Errors relating to signal resolution are much larger for a single threshold detection scheme than for multiple threshold schemes. This report provides methods for computing the effect of various conditions on the accuracy of a record obtained from an AVM. The equipment must be adapted to the site. Field reconnaissance and preinstallation analysis to detect possible problems are critical for proper installation and operation of an AVM system.
Spatial resolution limits for the localization of noise sources using direct sound mapping
NASA Astrophysics Data System (ADS)
Fernandez Comesaña, D.; Holland, K. R.; Fernandez-Grande, E.
2016-08-01
One of the main challenges arising from noise and vibration problems is how to identify the areas of a device, machine or structure that produce significant acoustic excitation, i.e. the localization of main noise sources. The direct visualization of sound, in particular sound intensity, has extensively been used for many years to locate sound sources. However, it is not yet well defined when two sources should be regarded as resolved by means of direct sound mapping. This paper derives the limits of the direct representation of sound pressure, particle velocity and sound intensity by exploring the relationship between spatial resolution, noise level and geometry. The proposed expressions are validated via simulations and experiments. It is shown that particle velocity mapping yields better results for identifying closely spaced sound sources than sound pressure or sound intensity, especially in the acoustic near-field.
Early sound symbolism for vowel sounds.
Spector, Ferrinne; Maurer, Daphne
2013-01-01
Children and adults consistently match some words (e.g., kiki) to jagged shapes and other words (e.g., bouba) to rounded shapes, providing evidence for non-arbitrary sound-shape mapping. In this study, we investigated the influence of vowels on sound-shape matching in toddlers, using four contrasting pairs of nonsense words differing in vowel sound (/i/ as in feet vs. /o/ as in boat) and four rounded-jagged shape pairs. Crucially, we used reduplicated syllables (e.g., kiki vs. koko) rather than confounding vowel sound with consonant context and syllable variability (e.g., kiki vs. bouba). Toddlers consistently matched words with /o/ to rounded shapes and words with /i/ to jagged shapes (p < 0.01). The results suggest that there may be naturally biased correspondences between vowel sound and shape.
Category 5: Sound Generation in Viscous Problems
NASA Technical Reports Server (NTRS)
Lee, Soogab; Henderson, Brenda
2004-01-01
Two problems are considered. Problem 1: Aeolian tones, sound generation by flow over cylinders, are relevant to airframe and power plant noise (heat exchanger, power transmission lines and chimneys). The purpose of this problem is to test the ability of a CFD/CAA code to accurately predict sound generation by viscous flows and sound propagation through interactions between acoustic wave & solid wall and between acoustic waves & shear layers. Problem 2: Sound generation by flow over a cavity.Air flows over the cavity shown below with a mean approach flow velocity of 50 m/s. The boundary layer that develops over the flat plate is turbulent with a thickness of 14 mm at the entrance to the cavity. Calculate the power spectra at the center of each cavit wall and the center of the cavity floor. Experimental data will be available for comparison.
Smalyuk, V. A.; Robey, H. F.; Döppner, T.; Jones, O. S.; Milovich, J. L.; Bachmann, B.; Baker, K. L.; Berzak Hopkins, L. F.; Bond, E.; Callahan, D. A.; Casey, D. T.; Celliers, P. M.; Cerjan, C.; Clark, D. S.; Dixit, S. N.; Edwards, M. J.; Haan, S. W.; Hamza, A. V.; Hurricane, O. A.; Jancaitis, K. S.; and others
2015-08-15
Radiation-driven, layered deuterium-tritium plastic capsule implosions were carried out using a new, 3-shock “adiabat-shaped” drive on the National Ignition Facility. The purpose of adiabat shaping is to use a stronger first shock, reducing hydrodynamic instability growth in the ablator. The shock can decay before reaching the deuterium-tritium fuel leaving it on a low adiabat and allowing higher fuel compression. The fuel areal density was improved by ∼25% with this new drive compared to similar “high-foot” implosions, while neutron yield was improved by more than 4 times, compared to “low-foot” implosions driven at the same compression and implosion velocity.
Salasnich, Luca
2010-12-15
We investigate the low-temperature thermodynamics of the unitary Fermi gas by introducing a model based on the zero-temperature spectra of both bosonic collective modes and fermonic single-particle excitations. We calculate the Helmholtz free energy and from it we obtain the entropy, the internal energy, and the chemical potential as a function of the temperature. By using these quantities and the Landau's expression for the superfluid density we determine analytically the superfluid fraction, the critical temperature, the first sound velocity, and the second sound velocity. We compare our analytical results with other theoretical predictions and experimental data of ultracold atoms and dilute neutron matter.
Sound wave transmission (image)
When sounds waves reach the ear, they are translated into nerve impulses. These impulses then travel to the brain where they are interpreted by the brain as sound. The hearing mechanisms within the inner ear, can ...
Taioli, Simone; Garberoglio, Giovanni; Simonucci, Stefano; Beccara, Silvio a; Aversa, Lucrezia; Nardi, Marco; Verucchi, Roberto; Iannotta, Salvatore; Dapor, Maurizio; and others
2013-01-28
In this work, we investigate the processes leading to the room-temperature growth of silicon carbide thin films by supersonic molecular beam epitaxy technique. We present experimental data showing that the collision of fullerene on a silicon surface induces strong chemical-physical perturbations and, for sufficient velocity, disruption of molecular bonds, and cage breaking with formation of nanostructures with different stoichiometric character. We show that in these out-of-equilibrium conditions, it is necessary to go beyond the standard implementations of density functional theory, as ab initio methods based on the Born-Oppenheimer approximation fail to capture the excited-state dynamics. In particular, we analyse the Si-C{sub 60} collision within the non-adiabatic nuclear dynamics framework, where stochastic hops occur between adiabatic surfaces calculated with time-dependent density functional theory. This theoretical description of the C{sub 60} impact on the Si surface is in good agreement with our experimental findings.
Taioli, Simone; Garberoglio, Giovanni; Simonucci, Stefano; a Beccara, Silvio; Aversa, Lucrezia; Nardi, Marco; Verucchi, Roberto; Iannotta, Salvatore; Dapor, Maurizio; Alfè, Dario
2013-01-28
In this work, we investigate the processes leading to the room-temperature growth of silicon carbide thin films by supersonic molecular beam epitaxy technique. We present experimental data showing that the collision of fullerene on a silicon surface induces strong chemical-physical perturbations and, for sufficient velocity, disruption of molecular bonds, and cage breaking with formation of nanostructures with different stoichiometric character. We show that in these out-of-equilibrium conditions, it is necessary to go beyond the standard implementations of density functional theory, as ab initio methods based on the Born-Oppenheimer approximation fail to capture the excited-state dynamics. In particular, we analyse the Si-C(60) collision within the non-adiabatic nuclear dynamics framework, where stochastic hops occur between adiabatic surfaces calculated with time-dependent density functional theory. This theoretical description of the C(60) impact on the Si surface is in good agreement with our experimental findings.
Acoustic Measurement of Potato Cannon Velocity
ERIC Educational Resources Information Center
Courtney, Michael; Courtney, Amy
2007-01-01
Potato cannon velocity can be measured with a digitized microphone signal. A microphone is attached to the potato cannon muzzle, and a potato is fired at an aluminum target about 10 m away. Flight time can be determined from the acoustic waveform by subtracting the time in the barrel and time for sound to return from the target. The potato…
Performance of Indirectly-Driven Capsule Implosions on NIF Using Adiabat-Shaping
NASA Astrophysics Data System (ADS)
Robey, Harry
2015-11-01
Indirectly-driven capsule implosions are being conducted on the National Ignition Facility (NIF). Early experiments conducted during the National Ignition Campaign (NIC) were driven by a laser pulse with a relatively low-power initial foot (``low-foot''), which was designed to keep the deuterium-tritium (DT) fuel on a low adiabat to achieve a high fuel areal density (ρR). These implosions were successful in achieving high ρR, but fell significantly short of the predicted neutron yield. A leading candidate to explain this degraded performance was ablation front instability growth, which can lead to the mixing of ablator material with the DT fuel layer and in extreme cases into the central DT hot spot. A subsequent campaign employing a modified laser pulse with increased power in the foot (``high-foot'') was designed to reduce the adverse effects of ablation front instability growth. These implosions have been very successful, increasing neutron yields by more than an order of magnitude, but at the expense of reduced fuel compression. To bridge these two regimes, a series of implosions have been designed to simultaneously achieve both high stability and high ρR. These implosions employ adiabat-shaping, where the driving laser pulse is high in the initial picket similar to the high-foot to retain the favorable stability properties at the ablation front. The remainder of the foot is similar to that of the low-foot, driving a lower velocity shock into the DT fuel to keep the adiabat low and compression high. This talk will present results and analysis of these implosions and will discuss implications for improved implosion performance. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
From sound to shape: auditory perception of drawing movements.
Thoret, Etienne; Aramaki, Mitsuko; Kronland-Martinet, Richard; Velay, Jean-Luc; Ystad, Sølvi
2014-06-01
This study investigates the human ability to perceive biological movements through friction sounds produced by drawings and, furthermore, the ability to recover drawn shapes from the friction sounds generated. In a first experiment, friction sounds, real-time synthesized and modulated by the velocity profile of the drawing gesture, revealed that subjects associated a biological movement to those sounds whose timbre variations were generated by velocity profiles following the 1/3 power law. This finding demonstrates that sounds can adequately inform about human movements if their acoustic characteristics are in accordance with the kinematic rule governing actual movements. Further investigations of our ability to recognize drawn shapes were carried out in 2 association tasks in which both recorded and synthesized sounds had to be associated to both distinct and similar visual shapes. Results revealed that, for both synthesized and recorded sounds, subjects made correct associations for distinct shapes, although some confusion was observed for similar shapes. The comparisons made between recorded and synthesized sounds lead to conclude that the timbre variations induced by the velocity profile enabled the shape recognition. The results are discussed in the context of the ecological and ideomotor frameworks.
Lemaitre, Guillaume; Heller, Laurie M.; Navolio, Nicole; Zúñiga-Peñaranda, Nicolas
2015-01-01
We report a series of experiments about a little-studied type of compatibility effect between a stimulus and a response: the priming of manual gestures via sounds associated with these gestures. The goal was to investigate the plasticity of the gesture-sound associations mediating this type of priming. Five experiments used a primed choice-reaction task. Participants were cued by a stimulus to perform response gestures that produced response sounds; those sounds were also used as primes before the response cues. We compared arbitrary associations between gestures and sounds (key lifts and pure tones) created during the experiment (i.e. no pre-existing knowledge) with ecological associations corresponding to the structure of the world (tapping gestures and sounds, scraping gestures and sounds) learned through the entire life of the participant (thus existing prior to the experiment). Two results were found. First, the priming effect exists for ecological as well as arbitrary associations between gestures and sounds. Second, the priming effect is greatly reduced for ecologically existing associations and is eliminated for arbitrary associations when the response gesture stops producing the associated sounds. These results provide evidence that auditory-motor priming is mainly created by rapid learning of the association between sounds and the gestures that produce them. Auditory-motor priming is therefore mediated by short-term associations between gestures and sounds that can be readily reconfigured regardless of prior knowledge. PMID:26544884
NASA Technical Reports Server (NTRS)
Liepmann, H. W.; Torczynski, J. R.
1983-01-01
Second sound techniques were used to study superfluid helium. Second sound shock waves produced relative velocities in the bulk fluid. Maximum counterflow velocities produced in this way are found to follow the Langer-Fischer prediction for the fundamental critical velocity in its functional dependence on temperature and pressure. Comparison of successive shock and rotating experiments provides strong evidence that breakdown results in vorticity production in the flow behind the shock. Schlieren pictures have verified the planar nature of second sound shocks even after multiple reflections. The nonlinear theory of second sound was repeatedly verified in its prediction of double shocks and other nonlinear phenomena.
NASA Astrophysics Data System (ADS)
Fujii, Ayaka; Wakatsuki, Naoto; Mizutani, Koichi
2016-01-01
A method of suppressing sound radiation to the far field of a near-field acoustic communication system using an evanescent sound field is proposed. The amplitude of the evanescent sound field generated from an infinite vibrating plate attenuates exponentially with increasing a distance from the surface of the vibrating plate. However, a discontinuity of the sound field exists at the edge of the finite vibrating plate in practice, which broadens the wavenumber spectrum. A sound wave radiates over the evanescent sound field because of broadening of the wavenumber spectrum. Therefore, we calculated the optimum distribution of the particle velocity on the vibrating plate to reduce the broadening of the wavenumber spectrum. We focused on a window function that is utilized in the field of signal analysis for reducing the broadening of the frequency spectrum. The optimization calculation is necessary for the design of window function suitable for suppressing sound radiation and securing a spatial area for data communication. In addition, a wide frequency bandwidth is required to increase the data transmission speed. Therefore, we investigated a suitable method for calculating the sound pressure level at the far field to confirm the variation of the distribution of sound pressure level determined on the basis of the window shape and frequency. The distribution of the sound pressure level at a finite distance was in good agreement with that obtained at an infinite far field under the condition generating the evanescent sound field. Consequently, the window function was optimized by the method used to calculate the distribution of the sound pressure level at an infinite far field using the wavenumber spectrum on the vibrating plate. According to the result of comparing the distributions of the sound pressure level in the cases with and without the window function, it was confirmed that the area whose sound pressure level was reduced from the maximum level to -50 dB was
Shortcuts to adiabaticity in a time-dependent box
Campo, A. del; Boshier, M. G.
2012-01-01
A method is proposed to drive an ultrafast non-adiabatic dynamics of an ultracold gas trapped in a time-dependent box potential. The resulting state is free from spurious excitations associated with the breakdown of adiabaticity, and preserves the quantum correlations of the initial state up to a scaling factor. The process relies on the existence of an adiabatic invariant and the inversion of the dynamical self-similar scaling law dictated by it. Its physical implementation generally requires the use of an auxiliary expulsive potential. The method is extended to a broad family of interacting many-body systems. As illustrative examples we consider the ultrafast expansion of a Tonks-Girardeau gas and of Bose-Einstein condensates in different dimensions, where the method exhibits an excellent robustness against different regimes of interactions and the features of an experimentally realizable box potential. PMID:22970340
Adiabatic circular polarizer based on chiral fiber grating.
Yang, Li; Xue, Lin-Lin; Li, Cheng; Su, Jue; Qian, Jing-Ren
2011-01-31
Based on the adiabatic coupling principle, a new scheme of a broadband circular polarizer formed by twisting a high-birefringence (Hi-Bi) fiber with a slowly varying twist rate is proposed. The conditions of adiabatic coupling for the adiabatic polarizer are first identified through analytical derivations. These conditions are easily realized by choosing a reasonable variation of the twist rate. Moreover, the bandwidth of the polarizer is able to be directly determined by the twist rates at the two ends. Finally, the broadband characteristics of the polarizer are demonstrated by simulations. It is also shown that the performance of the polarizer can be remarkably improved by accomplishing a multi-mode phase-matching along the grating or by using of the couplings of the core mode to lossy modes.
Effect of dephasing on stimulated Raman adiabatic passage
Ivanov, P.A.; Vitanov, N.V.; Bergmann, K.
2004-12-01
This work explores the effect of phase relaxation on the population transfer efficiency in stimulated Raman adiabatic passage (STIRAP). The study is based on the Liouville equation, which is solved analytically in the adiabatic limit. The transfer efficiency of STIRAP is found to decrease exponentially with the dephasing rate; this effect is stronger for shorter pulse delays and weaker for larger delays, since the transition time is found to be inversely proportional to the pulse delay. Moreover, it is found that the transfer efficiency of STIRAP in the presence of dephasing does not depend on the peak Rabi frequencies at all, as long as they are sufficiently large to enforce adiabatic evolution; hence increasing the field intensity cannot reduce the dephasing losses. It is shown also that for any dephasing rate, the final populations of the initial state and the intermediate state are equal. For strong dephasing all three populations tend to (1/3)
Applications of chirped Raman adiabatic rapid passage to atom interferometry
NASA Astrophysics Data System (ADS)
Kotru, Krish; Butts, David L.; Kinast, Joseph M.; Johnson, David M. S.; Radojevic, Antonije M.; Timmons, Brian P.; Stoner, Richard E.
2012-02-01
We present robust atom optics, based on chirped Raman adiabatic rapid passage (ARP), in the context of atom interferometry. Such ARP light pulses drive coherent population transfer between two hyperfine ground states by sweeping the frequency difference of two fixed-intensity optical fields with large single photon detunings. Since adiabatic transfer is less sensitive to atom temperature and non-uniform Raman beam intensity than standard Raman pulses, this approach should improve the stability of atom interferometers operating in dynamic environments. In such applications, chirped Raman ARP may also provide advantages over the previously demonstrated stimulated Raman adiabatic passage (STIRAP) technique, which requires precise modulation of beam intensity and zeroing of the single photon detuning. We demonstrate a clock interferometer with chirped Raman ARP pulses, and compare its stability to that of a conventional Raman pulse interferometer. We also discuss potential improvements to inertially sensitive atom interferometers. Copyright 2011 by The Charles Stark Draper Laboratory, Inc. All rights reserved.
Adiabatic Pseudospectral Technique: Applications to Four Atom Molecules
NASA Astrophysics Data System (ADS)
Antikainen, Jyrki Tapio
1995-01-01
After the introduction, in chapter 2 we review some of the well established techniques used to solve the Schrodinger equation. The following methods are discussed: the Finite Basis Representation, the Discrete Variable Representation, the Basic Light basis set truncation, and the Lanczos tridiagonalization. After reviewing the previous techniques we present the main features of our Adiabatic Pseudospectral (APS) technique. The Adiabatic Pseudospectral technique is a synthesis of several powerful computational methods such as the sequential adiabatic basis set reduction, the iterative Lanczos diagonalization, the collocation techniques, and a careful implementation of the matrix -vector product for the Hamiltonian in the reduced adiabatic representation. In chapter 3 we use our adiabatic pseudospectral method (APS) to calculate energy levels of the H _2O_2 molecule up to 5000 cm ^{-1}. Reasonably high accuracy (a few wavenumbers) is achieved for a fully six dimensional calculation in a few hours of CPU time on an IBM 580 workstation. These results are a great improvement over previous calculations on the same system which required 50-100 times more computational effort for a similar level of accuracy. The method presented here is both general and robust. It will allow for routine studies of six dimensional potential surfaces and the associated spectroscopy, while making calculations on still larger systems feasible. In chapter 4 the adiabatic pseudospectral method is used to study the high energy vibrational levels of the H_2C_2 molecule. We calculate stimulated emission pumping spectra initialized by the excited electronic state vibrational trans-bent state ~ A_sp{u}{1 }3_{nu}_3 . The calculations show that with the APS-method we can easily investigate energy regions in the excess of 15,000 cm^{-1}; these high energy regions have been previously unattainable by computational techniques.
Refractive acoustic devices for airborne sound.
Cervera, F; Sanchis, L; Sánchez-Pérez, J V; Martínez-Sala, R; Rubio, C; Meseguer, F; López, C; Caballero, D; Sánchez-Dehesa, J
2002-01-14
We show that a sonic crystal made of periodic distributions of rigid cylinders in air acts as a new material which allows the construction of refractive acoustic devices for airborne sound. It is demonstrated that, in the long-wave regime, the crystal has low impedance and the sound is transmitted at subsonic velocities. Here, the fabrication and characterization of a convergent lens are presented. Also, an example of a Fabry-Perot interferometer based on this crystal is analyzed. It is concluded that refractive devices based on sonic crystals behave in a manner similar to that of optical systems.
Quantum dynamics by the constrained adiabatic trajectory method
Leclerc, A.; Jolicard, G.; Guerin, S.; Killingbeck, J. P.
2011-03-15
We develop the constrained adiabatic trajectory method (CATM), which allows one to solve the time-dependent Schroedinger equation constraining the dynamics to a single Floquet eigenstate, as if it were adiabatic. This constrained Floquet state (CFS) is determined from the Hamiltonian modified by an artificial time-dependent absorbing potential whose forms are derived according to the initial conditions. The main advantage of this technique for practical implementation is that the CFS is easy to determine even for large systems since its corresponding eigenvalue is well isolated from the others through its imaginary part. The properties and limitations of the CATM are explored through simple examples.
Dynamics with the effective adiabatic theory: The Bloch equations
NASA Astrophysics Data System (ADS)
Carmeli, Benny; Chandler, David
1988-07-01
This paper extends our earlier work on the effective adiabatic theory [J. Chem. Phys. 82, 3400 (1985)] to study relaxation of a two-level system coupled to a Gaussian dissipative bath—the spin-boson problem. Bloch equations are derived which, under the limited circumstances described herein, treat the role of bath fluctuations omitted in the equilibrium effective adiabatic reference system. Applications to the Lorentzian dissipative bath show that the theory agrees closely with numerical simulation results. Application to an Ohmic bath shows that the theory is in agreement with currently accepted results concerned with the problem of macroscopic quantum coherence.
Adiabatic State Conversion and Pulse Transmission in Optomechanical Systems
NASA Astrophysics Data System (ADS)
Tian, Lin
2012-04-01
Optomechanical systems with strong coupling can be a powerful medium for quantum state engineering of the cavity modes. Here, we show that quantum state conversion between cavity modes of distinctively different wavelengths can be realized with high fidelity by adiabatically varying the effective optomechanical couplings. The conversion fidelity for Gaussian states is derived by solving the Langevin equation in the adiabatic limit. Meanwhile, we also show that traveling photon pulses can be transmitted between different input and output channels with high fidelity and the output pulse can be engineered via the optomechanical couplings.
Gravitational Chern-Simons and the adiabatic limit
McLellan, Brendan
2010-12-15
We compute the gravitational Chern-Simons term explicitly for an adiabatic family of metrics using standard methods in general relativity. We use the fact that our base three-manifold is a quasiregular K-contact manifold heavily in this computation. Our key observation is that this geometric assumption corresponds exactly to a Kaluza-Klein Ansatz for the metric tensor on our three-manifold, which allows us to translate our problem into the language of general relativity. Similar computations have been performed by Guralnik et al.[Ann. Phys. 308, 222 (2008)], although not in the adiabatic context.
Critical stability of almost adiabatic convection in a rapidly rotating thick spherical shell
Starchenko, S. V.; Kotelnikova, M. S.
2013-02-15
In this work, the convection equations in the almost adiabatic approximation is studied for which the choice of physical parameters is primarily based on possible applications to the hydrodynamics of the deep interiors of the Earth and planets and moons of the terrestrial group. The initial system of partial differential equations (PDEs) was simplified to a single second-order ordinary differential equation for the pressure or vertical velocity component to investigate the linear stability of convection. The critical frequencies, modified Rayleigh numbers, and distributions of convection are obtained at various possible Prandtl numbers and in different thick fluid shells. An analytical WKB-type solution was obtained for the case when the inner radius of the shell is much smaller than the outer radius and convective sources are concentrated along the inner boundary.
The exact forces on classical nuclei in non-adiabatic charge transfer
Agostini, Federica; Abedi, Ali; Suzuki, Yasumitsu; Min, Seung Kyu; Gross, E. K. U.; Maitra, Neepa T.
2015-02-28
The decomposition of electronic and nuclear motion presented in Abedi et al. [Phys. Rev. Lett. 105, 123002 (2010)] yields a time-dependent potential that drives the nuclear motion and fully accounts for the coupling to the electronic subsystem. Here, we show that propagation of an ensemble of independent classical nuclear trajectories on this exact potential yields dynamics that are essentially indistinguishable from the exact quantum dynamics for a model non-adiabatic charge transfer problem. We point out the importance of step and bump features in the exact potential that are critical in obtaining the correct splitting of the quasiclassical nuclear wave packet in space after it passes through an avoided crossing between two Born-Oppenheimer surfaces and analyze their structure. Finally, an analysis of the exact potentials in the context of trajectory surface hopping is presented, including preliminary investigations of velocity-adjustment and the force-induced decoherence effect.
Phase transformations in an ascending adiabatic mixed-phase cloud volume
NASA Astrophysics Data System (ADS)
Pinsky, M.; Khain, A.; Korolev, A.
2015-04-01
Regimes of liquid-ice coexistence that may form in an adiabatic parcel ascending at constant velocity at freezing temperatures are investigated. Four zones with different microphysical structures succeeding one another along the vertical direction have been established. On the basis of a novel balance equation, analytical expressions are derived to determine the conditions specific for each of these zones. In particular, the necessary and sufficient conditions for formation of liquid water phase within an ascending parcel containing only ice particles are determined. The results are compared to findings reported in earlier studies. The role of the Wegener-Bergeron-Findeisen mechanism in the phase transformation is analyzed. The dependence of the phase relaxation time on height in the four zones is investigated on the basis of a novel analytical expression. The results obtained in the study can be instrumental for analysis and interpretation of observed mixed-phase clouds.
The effect of adiabatic focusing upon charged particle propagation in random magnetic fields
NASA Technical Reports Server (NTRS)
Earl, J. A.
1975-01-01
Charged particles propagating along the diverging lines of force of a spatially inhomogeneous guiding field were considered as they are scattered by random fields. Their longitudinal transport is described in terms of the eigenfunctions of a Sturm-Liouville operator incorporating the effect of adiabatic focussing along with that of scattering. The relaxation times and characteristic velocities are graphed and tabulated. The particle density is evaluated as a function of space and time for two different regimes. In the first regime (relatively weak focussing), a diffusive mode of propagation is dominant but coherent modes are also dominant. In the second regime (strong focussing), diffusion does not occur and the propagation is purely coherent. This supercoherent mode corresponds exactly to the so-called scatter-free propagation of kilovolt solar flare electrons. On a larger scale, focussed transport provides an interpretation of many observed characteristics of extragalactic radio sources.
Sound Power Determination Using Sound Intensity Measurements: Applications and Extensions
NASA Astrophysics Data System (ADS)
Yang, Shaobo
1995-01-01
The determination of sound power using sound intensity measurements is one of the most important developments in acoustics since the advent of digital signal processing techniques and FFT (fast Fourier transform) techniques in 1970's. Sound power determination using sound intensity measurements is the only way to precisely determine the sound power of noise sources in operating conditions when other noise sources are operating simultaneously. Sound power determination from sound intensity measurements largely obviates the need for special purpose test facilities, such as an anechoic room or a reverberation room. The determination of sound power from sound intensity measurements has many distinct advantages over the traditional determination of the sound power from sound pressure, and it will soon become the dominant method in the determination of the sound power of noise sources in-situ. Sound intensity measurements have been successfully applied to the determination of the sound power levels of noise sources in laboratory conditions, and of small machinery noise sources. The full scale application of this new technique to industrial machinery noise sources is certainly of importance for practical purposes. This dissertation mainly describes progress made in research on the application of sound intensity measurements for the determination of the sound power of noise sources. Results concerning the sound power determination from sound intensity measurements in the following areas are discussed: sound power determination from sound intensity measurements at low frequency, error analysis of sound intensity estimates at low frequency, and sound power determination from sound intensity measurements in the presence of air flow, sound power determination from sound intensity measurements in the presence of strong background noise and some practical considerations on the application of the sound intensity technique to in-situ sound power determination.
NASA Astrophysics Data System (ADS)
Hoover, Wm. G.; Hoover, C. G.
2009-04-01
We compare nonlinear stresses and temperatures for adiabatic-shear flows, using up to 262 144 particles, with those from corresponding homogeneous and inhomogeneous flows. Two varieties of kinetic temperature tensors are compared to the configurational temperatures. This comparison of temperatures led us to two findings beyond our original goal of analyzing shear algorithms. First, we found an improved form for local instantaneous velocity fluctuations, as calculated with smooth-particle weighting functions. Second, we came upon the previously unrecognized contribution of rotation to the configurational temperature.
Adiabatic frequency conversion with a sign flip in the coupling
NASA Astrophysics Data System (ADS)
Hristova, H. S.; Rangelov, A. A.; Montemezzani, G.; Vitanov, N. V.
2016-09-01
Adiabatic frequency conversion is a method recently developed in nonlinear optics [H. Suchowski, D. Oron, A. Arie, and Y. Silberberg, Phys. Rev. A 78, 063821 (2008), 10.1103/PhysRevA.78.063821], using ideas from the technique of rapid adiabatic passage (RAP) via a level crossing in quantum physics. In this method, the coupling coefficients are constant and the phase mismatch is chirped adiabatically. In this work, we propose another method for adiabatic frequency conversion, in which the phase mismatch is constant and the coupling is a pulse-shaped function with a sign flip (i.e., a phase step of π ) at its maximum. Compared to the RAP method, our technique has comparable efficiency but it is simpler to implement for it only needs two bulk crystals with opposite χ(2 ) nonlinearity. Moreover, because our technique requires constant nonzero frequency mismatch and has zero conversion efficiency on exact frequency matching, it can be used as a frequency filter.
Failure of geometric electromagnetism in the adiabatic vector Kepler problem
Anglin, J.R.; Schmiedmayer, J.
2004-02-01
The magnetic moment of a particle orbiting a straight current-carrying wire may precess rapidly enough in the wire's magnetic field to justify an adiabatic approximation, eliminating the rapid time dependence of the magnetic moment and leaving only the particle position as a slow degree of freedom. To zeroth order in the adiabatic expansion, the orbits of the particle in the plane perpendicular to the wire are Keplerian ellipses. Higher-order postadiabatic corrections make the orbits precess, but recent analysis of this 'vector Kepler problem' has shown that the effective Hamiltonian incorporating a postadiabatic scalar potential ('geometric electromagnetism') fails to predict the precession correctly, while a heuristic alternative succeeds. In this paper we resolve the apparent failure of the postadiabatic approximation, by pointing out that the correct second-order analysis produces a third Hamiltonian, in which geometric electromagnetism is supplemented by a tensor potential. The heuristic Hamiltonian of Schmiedmayer and Scrinzi is then shown to be a canonical transformation of the correct adiabatic Hamiltonian, to second order. The transformation has the important advantage of removing a 1/r{sup 3} singularity which is an artifact of the adiabatic approximation.
Fast Quasi-Adiabatic Gas Cooling: An Experiment Revisited
ERIC Educational Resources Information Center
Oss, S.; Gratton, L. M.; Calza, G.; Lopez-Arias, T.
2012-01-01
The well-known experiment of the rapid expansion and cooling of the air contained in a bottle is performed with a rapidly responsive, yet very cheap thermometer. The adiabatic, low temperature limit is approached quite closely and measured with our apparatus. A straightforward theoretical model for this process is also presented and discussed.…
Adiabatic compression and radiative compression of magnetic fields
Woods, C.H.
1980-02-12
Flux is conserved during mechanical compression of magnetic fields for both nonrelativistic and relativistic compressors. However, the relativistic compressor generates radiation, which can carry up to twice the energy content of the magnetic field compressed adiabatically. The radiation may be either confined or allowed to escape.
Digitized adiabatic quantum computing with a superconducting circuit.
Barends, R; Shabani, A; Lamata, L; Kelly, J; Mezzacapo, A; Las Heras, U; Babbush, R; Fowler, A G; Campbell, B; Chen, Yu; Chen, Z; Chiaro, B; Dunsworth, A; Jeffrey, E; Lucero, E; Megrant, A; Mutus, J Y; Neeley, M; Neill, C; O'Malley, P J J; Quintana, C; Roushan, P; Sank, D; Vainsencher, A; Wenner, J; White, T C; Solano, E; Neven, H; Martinis, John M
2016-06-09
Quantum mechanics can help to solve complex problems in physics and chemistry, provided they can be programmed in a physical device. In adiabatic quantum computing, a system is slowly evolved from the ground state of a simple initial Hamiltonian to a final Hamiltonian that encodes a computational problem. The appeal of this approach lies in the combination of simplicity and generality; in principle, any problem can be encoded. In practice, applications are restricted by limited connectivity, available interactions and noise. A complementary approach is digital quantum computing, which enables the construction of arbitrary interactions and is compatible with error correction, but uses quantum circuit algorithms that are problem-specific. Here we combine the advantages of both approaches by implementing digitized adiabatic quantum computing in a superconducting system. We tomographically probe the system during the digitized evolution and explore the scaling of errors with system size. We then let the full system find the solution to random instances of the one-dimensional Ising problem as well as problem Hamiltonians that involve more complex interactions. This digital quantum simulation of the adiabatic algorithm consists of up to nine qubits and up to 1,000 quantum logic gates. The demonstration of digitized adiabatic quantum computing in the solid state opens a path to synthesizing long-range correlations and solving complex computational problems. When combined with fault-tolerance, our approach becomes a general-purpose algorithm that is scalable.
Cosmological solutions in spatially curved universes with adiabatic particle production
NASA Astrophysics Data System (ADS)
Aresté Saló, Llibert; de Haro, Jaume
2017-03-01
We perform a qualitative and thermodynamic study of two models when one takes into account adiabatic particle production. In the first one, there is a constant particle production rate, which leads to solutions depicting the current cosmic acceleration but without inflation. The other one has solutions that unify the early and late time acceleration. These solutions converge asymptotically to the thermal equilibrium.
A Kinetic Study of the Adiabatic Polymerization of Acrylamide.
ERIC Educational Resources Information Center
Thomson, R. A. M.
1986-01-01
Discusses theory, procedures, and results for an experiment which demonstrates the application of basic physics to chemical problems. The experiment involves the adiabatic process, in which polymerization carried out in a vacuum flask is compared to the theoretical prediction of the model with the temperature-time curve obtained in practice. (JN)
Reversibility and energy dissipation in adiabatic superconductor logic.
Takeuchi, Naoki; Yamanashi, Yuki; Yoshikawa, Nobuyuki
2017-12-01
Reversible computing is considered to be a key technology to achieve an extremely high energy efficiency in future computers. In this study, we investigated the relationship between reversibility and energy dissipation in adiabatic superconductor logic. We analyzed the evolution of phase differences of Josephson junctions in the reversible quantum-flux-parametron (RQFP) gate and confirmed that the phase differences can change time reversibly, which indicates that the RQFP gate is physically, as well as logically, reversible. We calculated energy dissipation required for the RQFP gate to perform a logic operation and numerically demonstrated that the energy dissipation can fall below the thermal limit, or the Landauer bound, by lowering operation frequencies. We also investigated the 1-bit-erasure gate as a logically irreversible gate and the quasi-RQFP gate as a physically irreversible gate. We calculated the energy dissipation of these irreversible gates and showed that the energy dissipation of these gate is dominated by non-adiabatic state changes, which are induced by unwanted interactions between gates due to logical or physical irreversibility. Our results show that, in reversible computing using adiabatic superconductor logic, logical and physical reversibility are required to achieve energy dissipation smaller than the Landauer bound without non-adiabatic processes caused by gate interactions.
Adiabatic State Conversion and Photon Transmission in Optomechanical Systems
NASA Astrophysics Data System (ADS)
Tian, Lin
2012-02-01
Light-matter interaction in optomechanical systems in the strong coupling regime can be explored as a tool to transfer cavity states and to transmit photon pulses. Here, we show that quantum state conversion between cavity modes with different wavelengths can be realized with high fidelity by adiabatically varying the effective optomechanical couplings. During this adiabatic process, the quantum state is preserved in the dark mode of the cavities, similar to the adiabatic transfer schemes in EIT systems. The fidelity for gaussian states is derived by solving the Langevin equation in the adiabatic limit and shows negligible dependence on the mechanical noise. We also show that an input pulse can be transmitted to an output channel with a different wavelength via the effective optomechanical couplings. The condition for optimal transmission is derived in the frequency domain. Input pulses with a narrow spectral width can be transmitted with high fidelity. For input pulses with a large spectral width, the shape of the output pulses can be manipulated by applying time-dependent effective couplings. (1) L. Tian, arXiv:1111.2119. (2) L. Tian and H. L. Wang, Phys. Rev. A 82, 053806 (2010).
When an Adiabatic Irreversible Expansion or Compression Becomes Reversible
ERIC Educational Resources Information Center
Anacleto, Joaquim; Ferreira, J. M.; Soares, A. A.
2009-01-01
This paper aims to contribute to a better understanding of the concepts of a "reversible process" and "entropy". For this purpose, an adiabatic irreversible expansion or compression is analysed, by considering that an ideal gas is expanded (compressed), from an initial pressure P[subscript i] to a final pressure P[subscript f], by being placed in…
Dark energy and dark matter from an additional adiabatic fluid
NASA Astrophysics Data System (ADS)
Dunsby, Peter K. S.; Luongo, Orlando; Reverberi, Lorenzo
2016-10-01
The dark sector is described by an additional barotropic fluid which evolves adiabatically during the Universe's history and whose adiabatic exponent γ is derived from the standard definitions of specific heats. Although in general γ is a function of the redshift, the Hubble parameter and its derivatives, we find that our assumptions lead necessarily to solutions with γ =constant in a Friedmann-Lemaître-Robertson-Walker universe. The adiabatic fluid acts effectively as the sum of two distinct components, one evolving like nonrelativistic matter and the other depending on the value of the adiabatic index. This makes the model particularly interesting as a way of simultaneously explaining the nature of both dark energy and dark matter, at least at the level of the background cosmology. The Λ CDM model is included in this family of theories when γ =0 . We fit our model to supernovae Ia, H (z ) and baryonic acoustic oscillation data, discussing the model selection criteria. The implications for the early Universe and the growth of small perturbations in this model are also discussed.
Digitized adiabatic quantum computing with a superconducting circuit
NASA Astrophysics Data System (ADS)
Barends, R.; Shabani, A.; Lamata, L.; Kelly, J.; Mezzacapo, A.; Heras, U. Las; Babbush, R.; Fowler, A. G.; Campbell, B.; Chen, Yu; Chen, Z.; Chiaro, B.; Dunsworth, A.; Jeffrey, E.; Lucero, E.; Megrant, A.; Mutus, J. Y.; Neeley, M.; Neill, C.; O'Malley, P. J. J.; Quintana, C.; Roushan, P.; Sank, D.; Vainsencher, A.; Wenner, J.; White, T. C.; Solano, E.; Neven, H.; Martinis, John M.
2016-06-01
Quantum mechanics can help to solve complex problems in physics and chemistry, provided they can be programmed in a physical device. In adiabatic quantum computing, a system is slowly evolved from the ground state of a simple initial Hamiltonian to a final Hamiltonian that encodes a computational problem. The appeal of this approach lies in the combination of simplicity and generality; in principle, any problem can be encoded. In practice, applications are restricted by limited connectivity, available interactions and noise. A complementary approach is digital quantum computing, which enables the construction of arbitrary interactions and is compatible with error correction, but uses quantum circuit algorithms that are problem-specific. Here we combine the advantages of both approaches by implementing digitized adiabatic quantum computing in a superconducting system. We tomographically probe the system during the digitized evolution and explore the scaling of errors with system size. We then let the full system find the solution to random instances of the one-dimensional Ising problem as well as problem Hamiltonians that involve more complex interactions. This digital quantum simulation of the adiabatic algorithm consists of up to nine qubits and up to 1,000 quantum logic gates. The demonstration of digitized adiabatic quantum computing in the solid state opens a path to synthesizing long-range correlations and solving complex computational problems. When combined with fault-tolerance, our approach becomes a general-purpose algorithm that is scalable.
Sub-adiabatic perpendicular electron heating across high-Mach number collisionless shocks
NASA Astrophysics Data System (ADS)
Sundkvist, D. J.; Mozer, F.
2012-12-01
Spacecraft observations of a high Mach number quasi-perpendicular bow shock with high plasma beta have revealed electrons that were sub-adiabatic through the shock ramp because they were less heated than expected from conservation of the first adiabatic invariant. This stands out in contrast to existing theories of electron heating at collisionless shocks in which the electrons are adiabatically heated through compression or more-than-adiabatically heated due to additional effects such as anomalous resistivity induced by microinstabilites.
The influence of horizontally rotating sound on standing balance.
Gandemer, Lennie; Parseihian, Gaëtan; Kronland-Martinet, Richard; Bourdin, Christophe
2014-12-01
Postural control is known to be the result of the integration and processing of various sensory inputs by the central nervous system. Among the various afferent inputs, the role of auditory information in postural regulation has been addressed in relatively few studies, which led to conflicting results. The purpose of the present study was to investigate the influence of a rotating auditory stimulus, delivered by an immersive 3D sound spatialization system, on the standing posture of young subjects. The postural sway of 20 upright, blindfolded subjects was recorded using a force platform. Use of various sound source rotation velocities followed by sudden immobilization of the sound was compared with two control conditions: no sound and a stationary sound source. The experiment showed that subjects reduced their body sway amplitude and velocity in the presence of rotating sound compared with the control conditions. The faster the sound source was rotating, the greater the reduction in subject body sway. Moreover, disruption of subject postural regulation was observed as soon as the sound source was immobilized. These results suggest that auditory information cannot be neglected in postural control and that it acts as additional information influencing postural regulation.
Exploring Noise: Sound Pollution.
ERIC Educational Resources Information Center
Rillo, Thomas J.
1979-01-01
Part one of a three-part series about noise pollution and its effects on humans. This section presents the background information for teachers who are preparing a unit on sound. The next issues will offer learning activities for measuring the effects of sound and some references. (SA)
ERIC Educational Resources Information Center
Brown, Tom; Boehringer, Kim
2007-01-01
Students in a fourth-grade class participated in a series of dynamic sound learning centers followed by a dramatic capstone event--an exploration of the amazing Trashcan Whoosh Waves. It's a notoriously difficult subject to teach, but this hands-on, exploratory approach ignited student interest in sound, promoted language acquisition, and built…
Operational sounding algorithms
NASA Technical Reports Server (NTRS)
Smith, W. L.
1980-01-01
The analytical equations used to interpret TIROS-N sounding radiances for operational applications are presented. Both the National Environmental Satellite System (NESS) Global Operational Synoptic Scale and the NESS/University of Wisconsin (UW) North American Mesoscale Sounding Production Systems are considered.
ERIC Educational Resources Information Center
Smits, Roel; Sereno, Joan; Jongman, Allard
2006-01-01
The authors conducted 4 experiments to test the decision-bound, prototype, and distribution theories for the categorization of sounds. They used as stimuli sounds varying in either resonance frequency or duration. They created different experimental conditions by varying the variance and overlap of 2 stimulus distributions used in a training phase…
ERIC Educational Resources Information Center
Burns, Gary
Based on the argument that (contrary to critical opinion) the musicians in the various bands associated with Bosstown Sound were indeed talented, cohesive individuals and that the bands' lack of renown was partially a result of ill-treatment by record companies and the press, this paper traces the development of the Bosstown Sound from its…
NASA Astrophysics Data System (ADS)
Matignon, Christophe; Desbiens, Nicolas; Sorin, Remy; Dubois, Vincent
2011-06-01
DSD is probably the most popular engineering tool used to model the dynamics of detonation. In this model the normal shock velocity (Dn) depends only on the local curvature (k) of the front. One way to reproduce this behavior is to construct a model for the explosive which obeys the 1D quasi-steady weakly curved detonation theory1. In its simplest form, such a model is composed of a reactive equation of state (ideal mixture of a burnt unburnt phases) coupled with a single step burning law. To complete the description of the reactive EOS different authors2,3 proposed various closure hypotheses (isobaric isothermal, isobaric adiabatic, isodensity isothermal,...). Given this form of the EOS, the rate law is then calibrated to match the experimental detonation velocity-curvature curve. In this paper we theoretically examine the influence of the EOS closure hypotheses on the (Dn,k) curve. As the 1D curved theory of detonation is extremely sensitive to the calculation of the sonic surface downstream the reaction zone, we show that the effect of a particular closure law for the mixture can have a dramatic effect whenever it alters the sound speed calculation at the end of the reaction zone.
A study of sound generation in subsonic rotors, volume 1
NASA Technical Reports Server (NTRS)
Chalupnik, J. D.; Clark, L. T.
1975-01-01
A model for the prediction of wake related sound generation by a single airfoil is presented. It is assumed that the net force fluctuation on an airfoil may be expressed in terms of the net momentum fluctuation in the near wake of the airfoil. The forcing function for sound generation depends on the spectra of the two point velocity correlations in the turbulent region near the airfoil trailing edge. The spectra of the two point velocity correlations were measured for the longitudinal and transverse components of turbulence in the wake of a 91.4 cm chord airfoil. A scaling procedure was developed using the turbulent boundary layer thickness. The model was then used to predict the radiated sound from a 5.1 cm chord airfoil. Agreement between the predicted and measured sound radiation spectra was good. The single airfoil results were extended to a rotor geometry, and various aerodynamic parameters were studied.
NASA Astrophysics Data System (ADS)
O'Donnell, Michael J.; Bisnovatyi, Ilia
2000-11-01
Computing practice today depends on visual output to drive almost all user interaction. Other senses, such as audition, may be totally neglected, or used tangentially, or used in highly restricted specialized ways. We have excellent audio rendering through D-A conversion, but we lack rich general facilities for modeling and manipulating sound comparable in quality and flexibility to graphics. We need coordinated research in several disciplines to improve the use of sound as an interactive information channel. Incremental and separate improvements in synthesis, analysis, speech processing, audiology, acoustics, music, etc. will not alone produce the radical progress that we seek in sonic practice. We also need to create a new central topic of study in digital audio research. The new topic will assimilate the contributions of different disciplines on a common foundation. The key central concept that we lack is sound as a general-purpose information channel. We must investigate the structure of this information channel, which is driven by the cooperative development of auditory perception and physical sound production. Particular audible encodings, such as speech and music, illuminate sonic information by example, but they are no more sufficient for a characterization than typography is sufficient for characterization of visual information. To develop this new conceptual topic of sonic information structure, we need to integrate insights from a number of different disciplines that deal with sound. In particular, we need to coordinate central and foundational studies of the representational models of sound with specific applications that illuminate the good and bad qualities of these models. Each natural or artificial process that generates informative sound, and each perceptual mechanism that derives information from sound, will teach us something about the right structure to attribute to the sound itself. The new Sound topic will combine the work of computer
Sideband excitation of trapped ions by rapid adiabatic passage for manipulation of motional states
Watanabe, T.; Nomura, S.; Toyoda, K.; Urabe, S.
2011-09-15
We describe an analysis and experimental results of the manipulation of motional states of a single trapped {sup 40}Ca{sup +} ion based on sideband excitation by rapid adiabatic passage. When the sideband transition is excited by rapid adiabatic passage, adiabaticity may be affected by ac Stark shifts. We investigate the influence of ac Stark shifts and compensate for these shifts with an additional laser field. This makes the population transfer by rapid adiabatic passage more robust with respect to experimental parameters. Finally, we manipulate the motional states and generate motional Fock states of a single {sup 40}Ca{sup +} ion by rapid adiabatic passage with ac Stark compensation.
Photoacoustic Sounds from Meteors
Spalding, Richard; Tencer, John; Sweatt, William; Conley, Benjamin; Hogan, Roy; Boslough, Mark; Gonzales, GiGi; Spurný, Pavel
2017-01-01
Concurrent sound associated with very bright meteors manifests as popping, hissing, and faint rustling sounds occurring simultaneously with the arrival of light from meteors. Numerous instances have been documented with −11 to −13 brightness. These sounds cannot be attributed to direct acoustic propagation from the upper atmosphere for which travel time would be several minutes. Concurrent sounds must be associated with some form of electromagnetic energy generated by the meteor, propagated to the vicinity of the observer, and transduced into acoustic waves. Previously, energy propagated from meteors was assumed to be RF emissions. This has not been well validated experimentally. Herein we describe experimental results and numerical models in support of photoacoustic coupling as the mechanism. Recent photometric measurements of fireballs reveal strong millisecond flares and significant brightness oscillations at frequencies ≥40 Hz. Strongly modulated light at these frequencies with sufficient intensity can create concurrent sounds through radiative heating of common dielectric materials like hair, clothing, and leaves. This heating produces small pressure oscillations in the air contacting the absorbers. Calculations show that −12 brightness meteors can generate audible sound at ~25 dB SPL. The photoacoustic hypothesis provides an alternative explanation for this longstanding mystery about generation of concurrent sounds by fireballs. PMID:28145486
Photoacoustic Sounds from Meteors
NASA Astrophysics Data System (ADS)
Spalding, Richard; Tencer, John; Sweatt, William; Conley, Benjamin; Hogan, Roy; Boslough, Mark; Gonzales, Gigi; Spurný, Pavel
2017-02-01
Concurrent sound associated with very bright meteors manifests as popping, hissing, and faint rustling sounds occurring simultaneously with the arrival of light from meteors. Numerous instances have been documented with ‑11 to ‑13 brightness. These sounds cannot be attributed to direct acoustic propagation from the upper atmosphere for which travel time would be several minutes. Concurrent sounds must be associated with some form of electromagnetic energy generated by the meteor, propagated to the vicinity of the observer, and transduced into acoustic waves. Previously, energy propagated from meteors was assumed to be RF emissions. This has not been well validated experimentally. Herein we describe experimental results and numerical models in support of photoacoustic coupling as the mechanism. Recent photometric measurements of fireballs reveal strong millisecond flares and significant brightness oscillations at frequencies ≥40 Hz. Strongly modulated light at these frequencies with sufficient intensity can create concurrent sounds through radiative heating of common dielectric materials like hair, clothing, and leaves. This heating produces small pressure oscillations in the air contacting the absorbers. Calculations show that ‑12 brightness meteors can generate audible sound at ~25 dB SPL. The photoacoustic hypothesis provides an alternative explanation for this longstanding mystery about generation of concurrent sounds by fireballs.
Photoacoustic sounds from meteors
Spalding, Richard; Tencer, John; Sweatt, William; ...
2017-02-01
Concurrent sound associated with very bright meteors manifests as popping, hissing, and faint rustling sounds occurring simultaneously with the arrival of light from meteors. Numerous instances have been documented with –11 to –13 brightness. These sounds cannot be attributed to direct acoustic propagation from the upper atmosphere for which travel time would be several minutes. Concurrent sounds must be associated with some form of electromagnetic energy generated by the meteor, propagated to the vicinity of the observer, and transduced into acoustic waves. Previously, energy propagated from meteors was assumed to be RF emissions. This has not been well validated experimentally.more » Herein we describe experimental results and numerical models in support of photoacoustic coupling as the mechanism. Recent photometric measurements of fireballs reveal strong millisecond flares and significant brightness oscillations at frequencies ≥40 Hz. Strongly modulated light at these frequencies with sufficient intensity can create concurrent sounds through radiative heating of common dielectric materials like hair, clothing, and leaves. This heating produces small pressure oscillations in the air contacting the absorbers. Calculations show that –12 brightness meteors can generate audible sound at ~25 dB SPL. As a result, the photoacoustic hypothesis provides an alternative explanation for this longstanding mystery about generation of concurrent sounds by fireballs.« less
Thermal and viscous effects on sound waves: revised classical theory.
Davis, Anthony M J; Brenner, Howard
2012-11-01
In this paper the recently developed, bi-velocity model of fluid mechanics based on the principles of linear irreversible thermodynamics (LIT) is applied to sound propagation in gases taking account of first-order thermal and viscous dissipation effects. The results are compared and contrasted with the classical Navier-Stokes-Fourier results of Pierce for this same situation cited in his textbook. Comparisons are also made with the recent analyses of Dadzie and Reese, whose molecularly based sound propagation calculations furnish results virtually identical with the purely macroscopic LIT-based bi-velocity results below, as well as being well-supported by experimental data. Illustrative dissipative sound propagation examples involving application of the bi-velocity model to several elementary situations are also provided, showing the disjoint entropy mode and the additional, evanescent viscous mode.
NASA Astrophysics Data System (ADS)
Benjamin, Jeffrey L.
A distinguishing feature of the discipline of archaeology is its reliance upon sensory dependant investigation. As perceived by all of the senses, the felt environment is a unique area of archaeological knowledge. It is generally accepted that the emergence of industrial processes in the recent past has been accompanied by unprecedented sonic extremes. The work of environmental historians has provided ample evidence that the introduction of much of this unwanted sound, or "noise" was an area of contestation. More recent research in the history of sound has called for more nuanced distinctions than the noisy/quiet dichotomy. Acoustic archaeology tends to focus upon a reconstruction of sound producing instruments and spaces with a primary goal of ascertaining intentionality. Most archaeoacoustic research is focused on learning more about the sonic world of people within prehistoric timeframes while some research has been done on historic sites. In this thesis, by way of a meditation on industrial sound and the physical remains of the Quincy Mining Company blacksmith shop (Hancock, MI) in particular, I argue for an acceptance and inclusion of sound as artifact in and of itself. I am introducing the concept of an individual sound-form, or sonifact , as a reproducible, repeatable, representable physical entity, created by tangible, perhaps even visible, host-artifacts. A sonifact is a sound that endures through time, with negligible variability. Through the piecing together of historical and archaeological evidence, in this thesis I present a plausible sonifactual assemblage at the blacksmith shop in April 1916 as it may have been experienced by an individual traversing the vicinity on foot: an 'historic soundwalk.' The sensory apprehension of abandoned industrial sites is multi-faceted. In this thesis I hope to make the case for an acceptance of sound as a primary heritage value when thinking about the industrial past, and also for an increased awareness and acceptance
Jung, I.S.; Lee, J.S.
2000-01-01
Presented are experimental results describing the effects of orientation angle of film cooling holes on boundary layer temperature distributions and film cooling effectiveness. Film flow data were obtained from a row of five film cooling holes on a flat test plate. The inclination angle of the hole was fixed at 35 deg and four orientation angles of 0, 30, 60, and 90 deg were investigated. The velocity ratios surveyed were 0.5, 1.0, and 2.0. The boundary layer temperature distributions were measured at three downstream locations using 1 {micro}m platinum wire. Detailed adiabatic film cooling effectiveness distributions were measured using thermochromic liquid crystal. Results show that the increased lateral momentum in the case of large orientation angle injection strongly affects boundary layer temperature distributions. Temperature distribution characteristics are, in general, explained in the context of the interactions between injectant and free-stream fluid and between injectants issuing from adjacent holes. The adiabatic film cooling effectiveness distributions are discussed in connection with the boundary layer temperature distributions. Spanwise-averaged effectiveness distributions and space-averaged effectiveness distributions are also presented with respect to the velocity ratios and the orientation angles.
GPS Sounding Rocket Developments
NASA Technical Reports Server (NTRS)
Bull, Barton
1999-01-01
Sounding rockets are suborbital launch vehicles capable of carrying scientific payloads several hundred miles in altitude. These missions return a variety of scientific data including; chemical makeup and physical processes taking place in the atmosphere, natural radiation surrounding the Earth, data on the Sun, stars, galaxies and many other phenomena. In addition, sounding rockets provide a reasonably economical means of conducting engineering tests for instruments and devices used on satellites and other spacecraft prior to their use in more expensive activities. This paper addresses the NASA Wallops Island history of GPS Sounding Rocket experience since 1994 and the development of highly accurate and useful system.
1998-09-30
Sounding the Sun Antony Fraser-Smith STAR Laboratory Stanford University Stanford, CA 94305 phone: (650) 723-3684 fax: (650) 723-9251 email...TITLE AND SUBTITLE Sounding the Sun 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK...systems. The objective of our “Sounding the sun ” experiment is to detect earth-directed CME’s by using existing earth-based HF (3- 30 MHz) radar systems
Non-adiabatic dynamics of molecules in optical cavities
NASA Astrophysics Data System (ADS)
Kowalewski, Markus; Bennett, Kochise; Mukamel, Shaul
2016-02-01
Strong coupling of molecules to the vacuum field of micro cavities can modify the potential energy surfaces thereby opening new photophysical and photochemical reaction pathways. While the influence of laser fields is usually described in terms of classical field, coupling to the vacuum state of a cavity has to be described in terms of dressed photon-matter states (polaritons) which require quantized fields. We present a derivation of the non-adiabatic couplings for single molecules in the strong coupling regime suitable for the calculation of the dressed state dynamics. The formalism allows to use quantities readily accessible from quantum chemistry codes like the adiabatic potential energy surfaces and dipole moments to carry out wave packet simulations in the dressed basis. The implications for photochemistry are demonstrated for a set of model systems representing typical situations found in molecules.
Non-adiabatic dynamics of molecules in optical cavities
Kowalewski, Markus Bennett, Kochise; Mukamel, Shaul
2016-02-07
Strong coupling of molecules to the vacuum field of micro cavities can modify the potential energy surfaces thereby opening new photophysical and photochemical reaction pathways. While the influence of laser fields is usually described in terms of classical field, coupling to the vacuum state of a cavity has to be described in terms of dressed photon-matter states (polaritons) which require quantized fields. We present a derivation of the non-adiabatic couplings for single molecules in the strong coupling regime suitable for the calculation of the dressed state dynamics. The formalism allows to use quantities readily accessible from quantum chemistry codes like the adiabatic potential energy surfaces and dipole moments to carry out wave packet simulations in the dressed basis. The implications for photochemistry are demonstrated for a set of model systems representing typical situations found in molecules.
Adiabatic far-field sub-diffraction imaging.
Cang, Hu; Salandrino, Alessandro; Wang, Yuan; Zhang, Xiang
2015-08-10
The limited resolution of a conventional optical imaging system stems from the fact that the fine feature information of an object is carried by evanescent waves, which exponentially decays in space and thus cannot reach the imaging plane. We introduce here an adiabatic lens, which utilizes a geometrically conformal surface to mediate the interference of slowly decompressed electromagnetic waves at far field to form images. The decompression is satisfying an adiabatic condition, and by bridging the gap between far field and near field, it allows far-field optical systems to project an image of the near-field features directly. Using these designs, we demonstrated the magnification can be up to 20 times and it is possible to achieve sub-50 nm imaging resolution in visible. Our approach provides a means to extend the domain of geometrical optics to a deep sub-wavelength scale.
Engineering adiabaticity at an avoided crossing with optimal control
NASA Astrophysics Data System (ADS)
Chasseur, T.; Theis, L. S.; Sanders, Y. R.; Egger, D. J.; Wilhelm, F. K.
2015-04-01
We investigate ways to optimize adiabaticity and diabaticity in the Landau-Zener model with nonuniform sweeps. We show how diabaticity can be engineered with a pulse consisting of a linear sweep augmented by an oscillating term. We show that the oscillation leads to jumps in populations whose value can be accurately modeled using a model of multiple, photon-assisted Landau-Zener transitions, which generalizes work by Wubs et al. [New J. Phys. 7, 218 (2005)], 10.1088/1367-2630/7/1/218. We extend the study on diabaticity using methods derived from optimal control. We also show how to preserve adiabaticity with optimal pulses at limited time, finding a nonuniform quantum speed limit.
Adiabatic molecular-dynamics-simulation-method studies of kinetic friction
NASA Astrophysics Data System (ADS)
Zhang, J.; Sokoloff, J. B.
2005-06-01
An adiabatic molecular-dynamics method is developed and used to study the Muser-Robbins model for dry friction (i.e., nonzero kinetic friction in the slow sliding speed limit). In this model, dry friction between two crystalline surfaces rotated with respect to each other is due to mobile molecules (i.e., dirt particles) adsorbed at the interface. Our adiabatic method allows us to quickly locate interface potential-well minima, which become unstable during sliding of the surfaces. Since dissipation due to friction in the slow sliding speed limit results from mobile molecules dropping out of such unstable wells, our method provides a way to calculate dry friction, which agrees extremely well with results found by conventional molecular dynamics for the same system, but our method is more than a factor of 10 faster.
Steam bottoming cycle for an adiabatic diesel engine
NASA Technical Reports Server (NTRS)
Poulin, E.; Demier, R.; Krepchin, I.; Walker, D.
1984-01-01
Steam bottoming cycles using adiabatic diesel engine exhaust heat which projected substantial performance and economic benefits for long haul trucks were studied. Steam cycle and system component variables, system cost, size and performance were analyzed. An 811 K/6.90 MPa state of the art reciprocating expander steam system with a monotube boiler and radiator core condenser was selected for preliminary design. The costs of the diesel with bottoming system (TC/B) and a NASA specified turbocompound adiabatic diesel with aftercooling with the same total output were compared, the annual fuel savings less the added maintenance cost was determined to cover the increase initial cost of the TC/B system in a payback period of 2.3 years. Steam bottoming system freeze protection strategies were developed, technological advances required for improved system reliability are considered and the cost and performance of advanced systes are evaluated.
Adiabatic approximation and fluctuations in exciton-polariton condensates
NASA Astrophysics Data System (ADS)
Bobrovska, Nataliya; Matuszewski, Michał
2015-07-01
We study the relation between the models commonly used to describe the dynamics of nonresonantly pumped exciton-polariton condensates, namely the ones described by the complex Ginzburg-Landau equation, and by the open-dissipative Gross-Pitaevskii equation including a separate equation for the reservoir density. In particular, we focus on the validity of the adiabatic approximation and small density fluctuations approximation that allow one to reduce the coupled condensate-reservoir dynamics to a single partial differential equation. We find that the adiabatic approximation consists of three independent analytical conditions that have to be fulfilled simultaneously. By investigating stochastic versions of the two corresponding models, we verify that the breakdown of these approximations can lead to discrepancies in correlation lengths and distributions of fluctuations. Additionally, we consider the phase diffusion and number fluctuations of a condensate in a box, and show that self-consistent description requires treatment beyond the typical Bogoliubov approximation.
Confinement loss in adiabatic photonic crystal fiber tapers
NASA Astrophysics Data System (ADS)
Kuhlmey, Boris T.; Nguyen, Hong C.; Steel, M. J.; Eggleton, Benjamin J.
2006-09-01
We numerically study confinement loss in photonic crystal fiber (PCF) tapers and compare our results with previously published experimental data. Agreement between theory and experiment requires taking into account hole shrinkage during the tapering process, which we measure by using a noninvasive technique. We show that losses are fully explained within the adiabatic approximation and that they are closely linked to the existence of a fundamental core-mode cutoff. This cutoff is equivalent to the core-mode cutoff in depressed-cladding fibers, so that losses in PCF tapers can be obtained semiquantitatively from an equivalent depressed-cladding fiber model. Finally, we discuss the definition of adiabaticity in this open boundary problem.
Adiabatic far-field sub-diffraction imaging
Cang, Hu; Salandrino, Alessandro; Wang, Yuan; Zhang, Xiang
2015-01-01
The limited resolution of a conventional optical imaging system stems from the fact that the fine feature information of an object is carried by evanescent waves, which exponentially decays in space and thus cannot reach the imaging plane. We introduce here an adiabatic lens, which utilizes a geometrically conformal surface to mediate the interference of slowly decompressed electromagnetic waves at far field to form images. The decompression is satisfying an adiabatic condition, and by bridging the gap between far field and near field, it allows far-field optical systems to project an image of the near-field features directly. Using these designs, we demonstrated the magnification can be up to 20 times and it is possible to achieve sub-50 nm imaging resolution in visible. Our approach provides a means to extend the domain of geometrical optics to a deep sub-wavelength scale. PMID:26258769
Multidimensional Study of High-Adiabat OMEGA Cryogenic Experiments
NASA Astrophysics Data System (ADS)
Collins, T. J. B.; Betti, R.; Bose, A.; Christopherson, A. R.; Knauer, J. P.; Marozas, J. A.; Maximov, A. V.; Mora, A.; Radha, P. B.; Shang, W.; Shvydky, A.; Stoeckl, C.; Woo, K. M.; Varchas, G.
2016-10-01
Despite recent advances in modeling laser direct-drive inertial confinement fusion (ICF) experiments, there remains a predictability gap. This is particularly shown by the shortfall in hot-spot pressures inferred from OMEGA cryogenic implosions. To address this, a series of high-adiabat, cryogenic implosions were performed on OMEGA. These shots were performed with and without single-beam smoothing by spectral dispersion, at low and high drive intensities. These shots represent a regime where good agreement with simulation is expected because of the high adiabat. Multidimensional simulations of these shots will be presented with an emphasis on comparison with experimental indicators of departure from spherical symmetry (``1-D-ness''). The roles of short- and long-wavelength perturbations are considered. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.
Fluctuations of work in nearly adiabatically driven open quantum systems.
Suomela, S; Salmilehto, J; Savenko, I G; Ala-Nissila, T; Möttönen, M
2015-02-01
We extend the quantum jump method to nearly adiabatically driven open quantum systems in a way that allows for an accurate account of the external driving in the system-environment interaction. Using this framework, we construct the corresponding trajectory-dependent work performed on the system and derive the integral fluctuation theorem and the Jarzynski equality for nearly adiabatic driving. We show that such identities hold as long as the stochastic dynamics and work variable are consistently defined. We numerically study the emerging work statistics for a two-level quantum system and find that the conventional diabatic approximation is unable to capture some prominent features arising from driving, such as the continuity of the probability density of work. Our results reveal the necessity of using accurate expressions for the drive-dressed heat exchange in future experiments probing jump time distributions.
Reverse engineering of a nonlossy adiabatic Hamiltonian for non-Hermitian systems
NASA Astrophysics Data System (ADS)
Wu, Qi-Cheng; Chen, Ye-Hong; Huang, Bi-Hua; Xia, Yan; Song, Jie
2016-11-01
We generalize the quantum adiabatic theorem to the non-Hermitian system and build a strict adiabaticity condition to make the adiabatic evolution nonlossy when taking into account the effect of the adiabatic phase. According to the strict adiabaticity condition, the nonadiabatic couplings and the effect of the imaginary part of adiabatic phase should be eliminated as much as possible. Also, the non-Hermitian Hamiltonian reverse-engineering method is proposed for adiabatically driving an artificial quantum state. A concrete two-level system is adopted to show the usefulness of the reverse-engineering method. We obtain the desired target state by adjusting extra rotating magnetic fields at a predefined time. Furthermore, the numerical simulation shows that certain noise and dissipation in the systems are no longer undesirable but play a positive role in the scheme. Therefore, the scheme is quite useful for quantum information processing in some dissipative systems.
Xu, Kebiao; Xie, Tianyu; Li, Zhaokai; Xu, Xiangkun; Wang, Mengqi; Ye, Xiangyu; Kong, Fei; Geng, Jianpei; Duan, Changkui; Shi, Fazhan; Du, Jiangfeng
2017-03-31
The adiabatic quantum computation is a universal and robust method of quantum computing. In this architecture, the problem can be solved by adiabatically evolving the quantum processor from the ground state of a simple initial Hamiltonian to that of a final one, which encodes the solution of the problem. Adiabatic quantum computation has been proved to be a compatible candidate for scalable quantum computation. In this Letter, we report on the experimental realization of an adiabatic quantum algorithm on a single solid spin system under ambient conditions. All elements of adiabatic quantum computation, including initial state preparation, adiabatic evolution (simulated by optimal control), and final state read-out, are realized experimentally. As an example, we found the ground state of the problem Hamiltonian S_{z}I_{z} on our adiabatic quantum processor, which can be mapped to the factorization of 35 into its prime factors 5 and 7.
Geometric Phase for Adiabatic Evolutions of General Quantum States
Wu, Biao; Liu, Jie; Niu, Qian; Singh, David J
2005-01-01
The concept of a geometric phase (Berry's phase) is generalized to the case of noneigenstates, which is applicable to both linear and nonlinear quantum systems. This is particularly important to nonlinear quantum systems, where, due to the lack of the superposition principle, the adiabatic evolution of a general state cannot be described in terms of eigenstates. For linear quantum systems, our new geometric phase reduces to a statistical average of Berry's phases. Our results are demonstrated with a nonlinear two-level model.
Stellar oscillations - II - The non-adiabatic case
NASA Astrophysics Data System (ADS)
Samadi, R.; Belkacem, K.; Sonoi, T.
2015-02-01
A leap forward has been performed due to the space-borne missions, MOST, CoRoT and Kepler. They provided a wealth of observational data, and more precisely oscillation spectra, which have been (and are still) exploited to infer the internal structure of stars. While an adiabatic approach is often sufficient to get information on the stellar equilibrium structures it is not sufficient to get a full understanding of the physics of the oscillation. Indeed, it does not permit one to answer some fundamental questions about the oscillations, such as: What are the physical mechanisms responsible for the pulsations inside stars? What determines the amplitudes? To what extent the adiabatic approximation is valid? All these questions can only be addressed by considering the energy exchanges between the oscillations and the surrounding medium. This lecture therefore aims at considering the energetical aspects of stellar pulsations with particular emphasis on the driving and damping mechanisms. To this end, the full non-adiabatic equations are introduced and thoroughly discussed. Two types of pulsation are distinguished, namely the self-excited oscillations that result from an instability and the solar-like oscillations that result from a balance between driving and damping by turbulent convection. For each type, the main physical principles are presented and illustrated using recent observations obtained with the ultra-high precision photometry space-borne missions (MOST, CoRoT and Kepler). Finally, we consider in detail the physics of scaling relations, which relates the seismic global indices with the global stellar parameters and gave birth to the development of statistical (or ensemble) asteroseismology. Indeed, several of these relations rely on the same cause: the physics of non-adiabatic oscillations.
Adiabatic modulation of cnoidal wave by Kuznetsov - Ma soliton
NASA Astrophysics Data System (ADS)
Makarov, V. A.; Petnikova, V. M.; Shuvalov, V. V.
2016-08-01
The problem of nonlinear interaction of a cnoidal wave (a “fast” component of vector light field) with localized in time and periodic in space control signal in the form of Kuznetsov-Ma soliton (a "slow" component of the same field) is analytically solved in the adiabatic approximation. The conditions which must be fulfilled for stable propagation of the obtained solution with amplitude and frequency modulation are determined.
Adiabatic pipelining: a key to ternary computing with quantum dots.
Pečar, P; Ramšak, A; Zimic, N; Mraz, M; Lebar Bajec, I
2008-12-10
The quantum-dot cellular automaton (QCA), a processing platform based on interacting quantum dots, was introduced by Lent in the mid-1990s. What followed was an exhilarating period with the development of the line, the functionally complete set of logic functions, as well as more complex processing structures, however all in the realm of binary logic. Regardless of these achievements, it has to be acknowledged that the use of binary logic is in computing systems mainly the end result of the technological limitations, which the designers had to cope with in the early days of their design. The first advancement of QCAs to multi-valued (ternary) processing was performed by Lebar Bajec et al, with the argument that processing platforms of the future should not disregard the clear advantages of multi-valued logic. Some of the elementary ternary QCAs, necessary for the construction of more complex processing entities, however, lead to a remarkable increase in size when compared to their binary counterparts. This somewhat negates the advantages gained by entering the ternary computing domain. As it turned out, even the binary QCA had its initial hiccups, which have been solved by the introduction of adiabatic switching and the application of adiabatic pipeline approaches. We present here a study that introduces adiabatic switching into the ternary QCA and employs the adiabatic pipeline approach to successfully solve the issues of elementary ternary QCAs. What is more, the ternary QCAs presented here are sizewise comparable to binary QCAs. This in our view might serve towards their faster adoption.
Competing adiabatic Thouless pumps in enlarged parameter spaces
NASA Astrophysics Data System (ADS)
Lopes, Pedro L. e. S.; Ghaemi, Pouyan; Ryu, Shinsei; Hughes, Taylor L.
2016-12-01
The transfer of conserved charges through insulating matter via smooth deformations of the Hamiltonian is known as quantum adiabatic, or Thouless, pumping. Central to this phenomenon are Hamiltonians whose insulating gap is controlled by a multidimensional (usually two-dimensional) parameter space in which paths can be defined for adiabatic changes in the Hamiltonian, i.e., without closing the gap. Here, we extend the concept of Thouless pumps of band insulators by considering a larger, three-dimensional parameter space. We show that the connectivity of this parameter space is crucial for defining quantum pumps, demonstrating that, as opposed to the conventional two-dimensional case, pumped quantities depend not only on the initial and final points of Hamiltonian evolution but also on the class of the chosen path and preserved symmetries. As such, we distinguish the scenarios of closed/open paths of Hamiltonian evolution, finding that different closed cycles can lead to the pumping of different quantum numbers, and that different open paths may point to distinct scenarios for surface physics. As explicit examples, we consider models similar to simple models used to describe topological insulators, but with doubled degrees of freedom compared to a minimal topological insulator model. The extra fermionic flavors from doubling allow for extra gapping terms/adiabatic parameters—besides the usual topological mass which preserves the topology-protecting discrete symmetries—generating an enlarged adiabatic parameter space. We consider cases in one and three spatial dimensions, and our results in three dimensions may be realized in the context of crystalline topological insulators, as we briefly discuss.
Adiabatic Compression Sensitivity of Liquid Fuels and Monopropellants
2007-11-02
Sensitivity of Liquid Fuels and Monopropellants " 46’b Internat’I Instrumentation Syrup (Bellevue, WA, 30 Apr- 04 May 00) (Statement A) (Deadline: 30 Dec...99) Adiabatic Compression Sensitivity of Liquid Fuels and Monopropellants Ismail M. K. Ismail Tom W. Hawkins Senior Engineer/Scientist Group Leader...hazard sensitivity, propellants, fuels, oxidizers ABSTRACT Liquid rocket fuels and monopropellants can be sensitive to rapid compression. Such liquids
Detection of Sound Image Movement During Horizontal Head Rotation
Ohba, Kagesho; Iwaya, Yukio; Suzuki, Yôiti
2016-01-01
Movement detection for a virtual sound source was measured during the listener’s horizontal head rotation. Listeners were instructed to do head rotation at a given speed. A trial consisted of two intervals. During an interval, a virtual sound source was presented 60° to the right or left of the listener, who was instructed to rotate the head to face the sound image position. Then in one of a pair of intervals, the sound position was moved slightly in the middle of the rotation. Listeners were asked to judge the interval in a trial during which the sound stimuli moved. Results suggest that detection thresholds are higher when listeners do head rotation. Moreover, this effect was found to be independent of the rotation velocity. PMID:27698993
NASA Astrophysics Data System (ADS)
Inogamov, N. A.; Sunyaev, R. A.
2015-12-01
In the early Universe up to hydrogen recombination in the Universe, the radiation pressure was much greater than the pressure of baryons and electrons. Moreover, the energy density of cosmic microwave background (CMB) photons was greater than or close to the energy density contained in the rest mass of baryonic matter, i.e., the primordial plasma was a radiated-dominated one and the adiabatic index was close to 4/3. The small density perturbations from which the observed galaxies have grown grew as long as the characteristic perturbation scales exceeded the horizon of the Universe сt at that time. On smaller scales, the density perturbations were standing sound waves. Radiative viscosity and heat conduction must have led to the damping of sound waves on very small scales. After the discovery of the cosmic microwave background, J. Silk calculated the scales of this damping, which is now called Silk damping, knowing the CMBtemperature and assuming the density of baryons and electrons. Observations with the South Pole Telescope, the Atacama Cosmology Telescope, and the Planck satellite have revealed the predicted damping of acoustic peaks in the CMB power spectrum and confirmed one important prediction of the theory. In 1970, R.A. Sunyaev and Ya.B. Zeldovich showed that such energy release in the early Universe should lead to characteristic deviations of the CMB spectrum from the Planck one. The development of the technology of cryogenic detectors of submillimeter and millimeter wavelength radiation has made it possible to measure the CMB spectral distortions at 10-8 of its total intensity (PIXIE). This has sharply increased the interest of theoretical cosmologists in the problem of energy release when smallscale sound waves are damped. We have derived a relativistic formula for the energy of a standing sound wave in a photon-baryon-electron plasma from simple hydrodynamic and thermodynamic relations. This formula is applicable for an arbitrary relation between the
On optimal methods for adiabatic quantum state transformations
NASA Astrophysics Data System (ADS)
Somma, Rolando
2013-03-01
Many problems in science could be solved by preparing the low-energy quantum state (or any eigenstate) of a Hamiltonian. A common example is the Boolean satisfiability problem, where each clause can be mapped to the energy of an interacting many-body system, and the problem reduces to minimizing the energy. In quantum computing, adiabatic quantum state transformations (ASTs) provide a tool for preparing the quantum state. ASTs are conventionally implemented via slow or adiabatic perturbations to the Hamiltonian, relying on the quantum adiabatic theorem. Nevertheless, more efficient implementations of ASTs exist. In this talk I will review recently developed methods for ASTs that are more efficient and require less assumptions on the Hamiltonians than the conventional implementation. Such methods involve measurements of the states along the evolution path and have a best-case implementation cost of L/G, where L is the length of the (evolved) state path and G is a lower bound to the spectral gap of the Hamiltonians. I will show that this cost is optimal and comment on results of the gap amplification problem, where the goal is to reduce the cost by increasing G. We acknowledge support from NSF through the CCF program and the LDRD programs at Los Alamos National Laboratory and Sandia National Laboratories.
Non-adiabatic molecular dynamics by accelerated semiclassical Monte Carlo
White, Alexander J.; Gorshkov, Vyacheslav N.; Tretiak, Sergei; Mozyrsky, Dmitry
2015-07-07
Non-adiabatic dynamics, where systems non-radiatively transition between electronic states, plays a crucial role in many photo-physical processes, such as fluorescence, phosphorescence, and photoisomerization. Methods for the simulation of non-adiabatic dynamics are typically either numerically impractical, highly complex, or based on approximations which can result in failure for even simple systems. Recently, the Semiclassical Monte Carlo (SCMC) approach was developed in an attempt to combine the accuracy of rigorous semiclassical methods with the efficiency and simplicity of widely used surface hopping methods. However, while SCMC was found to be more efficient than other semiclassical methods, it is not yet as efficient as is needed to be used for large molecular systems. Here, we have developed two new methods: the accelerated-SCMC and the accelerated-SCMC with re-Gaussianization, which reduce the cost of the SCMC algorithm up to two orders of magnitude for certain systems. In many cases shown here, the new procedures are nearly as efficient as the commonly used surface hopping schemes, with little to no loss of accuracy. This implies that these modified SCMC algorithms will be of practical numerical solutions for simulating non-adiabatic dynamics in realistic molecular systems.
Dynamics of Quantum Adiabatic Evolution Algorithm for Number Partitioning
NASA Technical Reports Server (NTRS)
Smelyanskiy, Vadius; vonToussaint, Udo V.; Timucin, Dogan A.; Clancy, Daniel (Technical Monitor)
2002-01-01
We have developed a general technique to study the dynamics of the quantum adiabatic evolution algorithm applied to random combinatorial optimization problems in the asymptotic limit of large problem size n. We use as an example the NP-complete Number Partitioning problem and map the algorithm dynamics to that of an auxiliary quantum spin glass system with the slowly varying Hamiltonian. We use a Green function method to obtain the adiabatic eigenstates and the minimum exitation gap, gmin = O(n2(sup -n/2)), corresponding to the exponential complexity of the algorithm for Number Partitioning. The key element of the analysis is the conditional energy distribution computed for the set of all spin configurations generated from a given (ancestor) configuration by simultaneous flipping of a fixed number of spins. For the problem in question this distribution is shown to depend on the ancestor spin configuration only via a certain parameter related to the energy of the configuration. As the result, the algorithm dynamics can be described in terms of one-dimensional quantum diffusion in the energy space. This effect provides a general limitation of a quantum adiabatic computation in random optimization problems. Analytical results are in agreement with the numerical simulation of the algorithm.
Dynamics of Quantum Adiabatic Evolution Algorithm for Number Partitioning
NASA Technical Reports Server (NTRS)
Smelyanskiy, V. N.; Toussaint, U. V.; Timucin, D. A.
2002-01-01
We have developed a general technique to study the dynamics of the quantum adiabatic evolution algorithm applied to random combinatorial optimization problems in the asymptotic limit of large problem size n. We use as an example the NP-complete Number Partitioning problem and map the algorithm dynamics to that of an auxiliary quantum spin glass system with the slowly varying Hamiltonian. We use a Green function method to obtain the adiabatic eigenstates and the minimum excitation gap. g min, = O(n 2(exp -n/2), corresponding to the exponential complexity of the algorithm for Number Partitioning. The key element of the analysis is the conditional energy distribution computed for the set of all spin configurations generated from a given (ancestor) configuration by simultaneous flipping of a fixed number of spins. For the problem in question this distribution is shown to depend on the ancestor spin configuration only via a certain parameter related to 'the energy of the configuration. As the result, the algorithm dynamics can be described in terms of one-dimensional quantum diffusion in the energy space. This effect provides a general limitation of a quantum adiabatic computation in random optimization problems. Analytical results are in agreement with the numerical simulation of the algorithm.
The performance of the quantum adiabatic algorithm on spike Hamiltonians
NASA Astrophysics Data System (ADS)
Kong, Linghang; Crosson, Elizabeth
Spike Hamiltonians arise from optimization instances for which the adiabatic algorithm provably out performs classical simulated annealing. In this work, we study the efficiency of the adiabatic algorithm for solving the “the Hamming weight with a spike” problem by analyzing the scaling of the spectral gap at the critical point for various sizes of the barrier. Our main result is a rigorous lower bound on the minimum spectral gap for the adiabatic evolution when the bit-symmetric cost function has a thin but polynomially high barrier, which is based on a comparison argument and an improved variational ansatz for the ground state. We also adapt the discrete WKB method for the case of abruptly changing potentials and compare it with the predictions of the spin coherent instanton method which was previously used by Farhi, Goldstone and Gutmann. Finally, our improved ansatz for the ground state leads to a method for predicting the location of avoided crossings in the excited energy states of the thin spike Hamiltonian, and we use a recursion relation to understand the ordering of some of these avoided crossings as a step towards analyzing the previously observed diabatic cascade phenomenon.
Adiabatic shear mechanisms for the hard cutting process
NASA Astrophysics Data System (ADS)
Yue, Caixu; Wang, Bo; Liu, Xianli; Feng, Huize; Cai, Chunbin
2015-05-01
The most important consequence of adiabatic shear phenomenon is formation of sawtooth chip. Lots of scholars focused on the formation mechanism of sawtooth, and the research often depended on experimental approach. For the present, the mechanism of sawtooth chip formation still remains some ambiguous aspects. This study develops a combined numerical and experimental approach to get deeper understanding of sawtooth chip formation mechanism for Polycrystalline Cubic Boron Nitride (PCBN) tools orthogonal cutting hard steel GCr15. By adopting the Johnson-Cook material constitutive equations, the FEM simulation model established in this research effectively overcomes serious element distortions and cell singularity in high strain domain caused by large material deformation, and the adiabatic shear phenomenon is simulated successfully. Both the formation mechanism and process of sawtooth are simulated. Also, the change features regarding the cutting force as well as its effects on temperature are studied. More specifically, the contact of sawtooth formation frequency with cutting force fluctuation frequency is established. The cutting force and effect of cutting temperature on mechanism of adiabatic shear are investigated. Furthermore, the effects of the cutting condition on sawtooth chip formation are researched. The researching results show that cutting feed has the most important effect on sawtooth chip formation compared with cutting depth and speed. This research contributes a better understanding of mechanism, feature of chip formation in hard turning process, and supplies theoretical basis for the optimization of hard cutting process parameters.
Irreconcilable difference between quantum walks and adiabatic quantum computing
NASA Astrophysics Data System (ADS)
Wong, Thomas G.; Meyer, David A.
2016-06-01
Continuous-time quantum walks and adiabatic quantum evolution are two general techniques for quantum computing, both of which are described by Hamiltonians that govern their evolutions by Schrödinger's equation. In the former, the Hamiltonian is fixed, while in the latter, the Hamiltonian varies with time. As a result, their formulations of Grover's algorithm evolve differently through Hilbert space. We show that this difference is fundamental; they cannot be made to evolve along each other's path without introducing structure more powerful than the standard oracle for unstructured search. For an adiabatic quantum evolution to evolve like the quantum walk search algorithm, it must interpolate between three fixed Hamiltonians, one of which is complex and introduces structure that is stronger than the oracle for unstructured search. Conversely, for a quantum walk to evolve along the path of the adiabatic search algorithm, it must be a chiral quantum walk on a weighted, directed star graph with structure that is also stronger than the oracle for unstructured search. Thus, the two techniques, although similar in being described by Hamiltonians that govern their evolution, compute by fundamentally irreconcilable means.
Non-adiabatic molecular dynamics by accelerated semiclassical Monte Carlo
White, Alexander J.; Gorshkov, Vyacheslav N.; Tretiak, Sergei; ...
2015-07-07
Non-adiabatic dynamics, where systems non-radiatively transition between electronic states, plays a crucial role in many photo-physical processes, such as fluorescence, phosphorescence, and photoisomerization. Methods for the simulation of non-adiabatic dynamics are typically either numerically impractical, highly complex, or based on approximations which can result in failure for even simple systems. Recently, the Semiclassical Monte Carlo (SCMC) approach was developed in an attempt to combine the accuracy of rigorous semiclassical methods with the efficiency and simplicity of widely used surface hopping methods. However, while SCMC was found to be more efficient than other semiclassical methods, it is not yet as efficientmore » as is needed to be used for large molecular systems. Here, we have developed two new methods: the accelerated-SCMC and the accelerated-SCMC with re-Gaussianization, which reduce the cost of the SCMC algorithm up to two orders of magnitude for certain systems. In many cases shown here, the new procedures are nearly as efficient as the commonly used surface hopping schemes, with little to no loss of accuracy. This implies that these modified SCMC algorithms will be of practical numerical solutions for simulating non-adiabatic dynamics in realistic molecular systems.« less
Adiabatic dynamics with classical noise in optical lattice
NASA Astrophysics Data System (ADS)
Xu, Guanglei; Daley, Andrew
2016-05-01
The technique of adiabatic state preparation is an interesting potential tool for the realisation of sensitive many-body states with ultra-cold atoms at low temperatures. However, questions remain regarding the influence of classical noise in these adiabatic dynamics. We investigate such dynamics in a situation where a level dressing scheme can make amplitude noise in an optical lattice proportional to the Hamiltonian, leading to a quantum Zeno effect for non-adiabatic transitions. We compute the dynamics using stochastic many-body Schrödinger equation and master equation approaches. Taking the examples of 1D Bose-Hubbard model from Mott insulator phase to superfluid phase and comparing with analytical calculations for a two-level system, we demonstrate that when the total time for the process is limited, properly transformed noise can lead to an increased final fidelity in the state preparation. We consider the dynamics also in the presence of imperfections, studying the resulting heating and dephasing for the many-body states, and identifying optimal regimes for future experiments.
Adiabatic invariants for the regular region of the Dicke model
NASA Astrophysics Data System (ADS)
Bastarrachea-Magnani, M. A.; Relaño, A.; Lerma-Hernández, S.; López-del-Carpio, B.; Chávez-Carlos, J.; Hirsch, J. G.
2017-04-01
Adiabatic invariants for the non-integrable Dicke model are introduced. They are shown to provide approximate second integrals of motion in the energy region where the system exhibits a regular dynamics. This low-energy region, present for any set of values of the Hamiltonian parameters is described both with a semiclassical and a full quantum analysis in a broad region of the parameter space. Peres lattices in this region exhibit that many observables vary smoothly with energy, along distinct lines which beg for a formal description. It is demonstrated how the adiabatic invariants provide a rationale to their presence in many cases. They are built employing the Born–Oppenheimer approximation, valid when a fast system is coupled to a much slower one. As the Dicke model has one bosonic and one fermionic degree of freedom, two versions of the approximation are used, depending on which one is the faster. In both cases a noticeably accord with exact numerical results is obtained. The employment of the adiabatic invariants provides a simple and clear theoretical framework to study the physical phenomenology associated to these regimes, far beyond the energies where a quadratic approximation around the minimal energy configuration can be used.
Experimental implementation of an adiabatic quantum optimization algorithm
NASA Astrophysics Data System (ADS)
Steffen, Matthias; van Dam, Wim; Hogg, Tad; Breyta, Greg; Chuang, Isaac
2003-03-01
A novel quantum algorithm using adiabatic evolution was recently presented by Ed Farhi [1] and Tad Hogg [2]. This algorithm represents a remarkable discovery because it offers new insights into the usefulness of quantum resources. An experimental demonstration of an adiabatic algorithm has remained beyond reach because it requires an experimentally accessible Hamiltonian which encodes the problem and which must also be smoothly varied over time. We present tools to overcome these difficulties by discretizing the algorithm and extending average Hamiltonian techniques [3]. We used these techniques in the first experimental demonstration of an adiabatic optimization algorithm: solving an instance of the MAXCUT problem using three qubits and nuclear magnetic resonance techniques. We show that there exists an optimal run-time of the algorithm which can be predicted using a previously developed decoherence model. [1] E. Farhi et al., quant-ph/0001106 (2000) [2] T. Hogg, PRA, 61, 052311 (2000) [3] W. Rhim, A. Pines, J. Waugh, PRL, 24,218 (1970)
Analysis of a High-Adiabat Cryogenic Implosion on OMEGA
NASA Astrophysics Data System (ADS)
Christopherson, A. R.; Betti, R.; Nora, R.; Epstein, R.; Marshall, F. J.; Forrest, C. J.; Stoeckl, C.; Delettrez, J. A.; Radha, P. B.; Howard, J.
2014-10-01
The performance of high-adiabat implosions >~ 10 is marginally affected by nonuniformities because of the strong ablative stabilization. To test the validity of the one-dimensional (1-D) physics included in existing hydrocodes, a study of high-adiabat cryogenic DT implosions is carried out by comparing the results of 1-D simulations with several measured quantities. It is found that after including nonlocal transport, cross-beam energy transfer, and hot electrons, 1-D simulations reproduce most of the observables with reasonable accuracy. Since the analysis is applied to the only high-adiabat DT implosion fielded on OMEGA, these results do not fully validate the 1-D physics of current hydrocodes. However, this work shows the framework for establishing a validation capability of the 1-D physics of inertial confinement fusion implosions. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944 and the Office of Fusion Energy Sciences Number DE-FG02-04ER54786.
Canonical fluid thermodynamics. [variational principles of stability for compressible adiabatic flow
NASA Technical Reports Server (NTRS)
Schmid, L. A.
1974-01-01
The space-time integral of the thermodynamic pressure plays in a certain sense the role of the thermodynamic potential for compressible adiabatic flow. The stability criterion can be converted into a variational minimum principle by requiring the molar free-enthalpy and temperature to be generalized velocities. In the fluid context, the definition of proper-time differentiation involves the fluid velocity expressed in terms of three particle identity parameters. The pressure function is then converted into a functional which is the Lagrangian density of the variational principle. Being also a minimum principle, the variational principle provides a means for comparing the relative stability of different flows. For boundary conditions with a high degree of symmetry, as in the case of a uniformly expanding spherical gas box, the most stable flow is a rectilinear flow for which the world-trajectory of each particle is a straight line. Since the behavior of the interior of a freely expanding cosmic cloud may be expected to be similar to that of the fluid in the spherical box of gas, this suggests that the cosmic principle is a consequence of the laws of thermodynamics, rather than just an ad hoc postulate.
Sound Visualization and Holography
ERIC Educational Resources Information Center
Kock, Winston E.
1975-01-01
Describes liquid surface holograms including their application to medicine. Discusses interference and diffraction phenomena using sound wave scanning techniques. Compares focussing by zone plate to holographic image development. (GH)
2007-01-01
de Fuca Strait, Puget Sound and the Strait of Georgia ) for a considerable time of the year, predominantly from early spring until late fall (Ford and...the south- ern part of Georgia Strait, Boundary Passage, the southern Gulf Islands and the eastern end of Juan de Fuca Strait (Heimlich- Boran 1988...Figure 2. Distribution of SRKW during September 2006 in Puget Sound and the southern Strait of Georgia (Advanced Satellite Productions, Orca Network
Ecological sounds affect breath duration more than artificial sounds.
Murgia, Mauro; Santoro, Ilaria; Tamburini, Giorgia; Prpic, Valter; Sors, Fabrizio; Galmonte, Alessandra; Agostini, Tiziano
2016-01-01
Previous research has demonstrated that auditory rhythms affect both movement and physiological functions. We hypothesized that the ecological sounds of human breathing can affect breathing more than artificial sounds of breathing, varying in tones for inspiration and expiration. To address this question, we monitored the breath duration of participants exposed to three conditions: (a) ecological sounds of breathing, (b) artificial sounds of breathing having equal temporal features as the ecological sounds, (c) no sounds (control). We found that participants' breath duration variability was reduced in the ecological sound condition, more than in the artificial sound condition. We suggest that ecological sounds captured the timing of breathing better than artificial sounds, guiding as a consequence participants' breathing. We interpreted our results according to the Theory of Event Coding, providing further support to its validity, and suggesting its possible extension in the domain of physiological functions which are both consciously and unconsciously controlled.
Calculations of upper-mantle velocity from published Soviet earthquake data
Rodriquez, Robert G.
1965-01-01
The lack of information on mantle velocities and crustal structure of the U.S.S.R. has led to a preliminary examination of published Soviet earthquake bulletins in the hope of deriving useful velocity and structure information from the data they contain. Mantle velocities deduced from earthquake data on several Russian earthquakes are in excellent agreement with results of Soviet deep seismic sounding.
Determination of equivalent sound speed profiles for ray tracing in near-ground sound propagation.
Prospathopoulos, John M; Voutsinas, Spyros G
2007-09-01
The determination of appropriate sound speed profiles in the modeling of near-ground propagation using a ray tracing method is investigated using a ray tracing model which is capable of performing axisymmetric calculations of the sound field around an isolated source. Eigenrays are traced using an iterative procedure which integrates the trajectory equations for each ray launched from the source at a specific direction. The calculation of sound energy losses is made by introducing appropriate coefficients to the equations representing the effect of ground and atmospheric absorption and the interaction with the atmospheric turbulence. The model is validated against analytical and numerical predictions of other methodologies for simple cases, as well as against measurements for nonrefractive atmospheric environments. A systematic investigation for near-ground propagation in downward and upward refractive atmosphere is made using experimental data. Guidelines for the suitable simulation of the wind velocity profile are derived by correlating predictions with measurements.
Sound modes in holographic superfluids
Herzog, Christopher P.; Yarom, Amos
2009-11-15
Superfluids support many different types of sound waves. We investigate the relation between the sound waves in a relativistic and a nonrelativistic superfluid by using hydrodynamics to calculate the various sound speeds. Then, using a particular holographic scalar gravity realization of a strongly interacting superfluid, we compute first, second, and fourth sound speeds as a function of the temperature. The relativistic low temperature results for second sound differ from Landau's well known prediction for the nonrelativistic, incompressible case.
NASA Astrophysics Data System (ADS)
2001-06-01
Acoustic Oscillations in Solar-Twin "Alpha Cen A" Observed from La Silla by Swiss Team Summary Sound waves running through a star can help astronomers reveal its inner properties. This particular branch of modern astrophysics is known as "asteroseismology" . In the case of our Sun, the brightest star in the sky, such waves have been observed since some time, and have greatly improved our knowledge about what is going on inside. However, because they are much fainter, it has turned out to be very difficult to detect similar waves in other stars. Nevertheless, tiny oscillations in a solar-twin star have now been unambiguously detected by Swiss astronomers François Bouchy and Fabien Carrier from the Geneva Observatory, using the CORALIE spectrometer on the Swiss 1.2-m Leonard Euler telescope at the ESO La Silla Observatory. This telescope is mostly used for discovering exoplanets (see ESO PR 07/01 ). The star Alpha Centauri A is the nearest star visible to the naked eye, at a distance of a little more than 4 light-years. The new measurements show that it pulsates with a 7-minute cycle, very similar to what is observed in the Sun . Asteroseismology for Sun-like stars is likely to become an important probe of stellar theory in the near future. The state-of-the-art HARPS spectrograph , to be mounted on the ESO 3.6-m telescope at La Silla, will be able to search for oscillations in stars that are 100 times fainter than those for which such demanding observations are possible with CORALIE. PR Photo 23a/01 : Oscillations in a solar-like star (schematic picture). PR Photo 23b/01 : Acoustic spectrum of Alpha Centauri A , as observed with CORALIE. Asteroseismology: listening to the stars ESO PR Photo 23a/01 ESO PR Photo 23a/01 [Preview - JPEG: 357 x 400 pix - 96k] [Normal - JPEG: 713 x 800 pix - 256k] [HiRes - JPEG: 2673 x 3000 pix - 2.1Mb Caption : PR Photo 23a/01 is a graphical representation of resonating acoustic waves in the interior of a solar-like star. Red and blue
GPS Sounding Rocket Developments
NASA Technical Reports Server (NTRS)
Bull, Barton
1999-01-01
Sounding rockets are suborbital launch vehicles capable of carrying scientific payloads several hundred miles in altitude. These missions return a variety of scientific data including; chemical makeup and physical processes taking place In the atmosphere, natural radiation surrounding the Earth, data on the Sun, stars, galaxies and many other phenomena. In addition, sounding rockets provide a reasonably economical means of conducting engineering tests for instruments and devices used on satellites and other spacecraft prior to their use in more expensive activities. The NASA Sounding Rocket Program is managed by personnel from Goddard Space Flight Center Wallops Flight Facility (GSFC/WFF) in Virginia. Typically around thirty of these rockets are launched each year, either from established ranges at Wallops Island, Virginia, Poker Flat Research Range, Alaska; White Sands Missile Range, New Mexico or from Canada, Norway and Sweden. Many times launches are conducted from temporary launch ranges in remote parts of the world requi6ng considerable expense to transport and operate tracking radars. An inverse differential GPS system has been developed for Sounding Rocket. This paper addresses the NASA Wallops Island history of GPS Sounding Rocket experience since 1994 and the development of a high accurate and useful system.
Meteor fireball sounds identified
NASA Technical Reports Server (NTRS)
Keay, Colin
1992-01-01
Sounds heard simultaneously with the flight of large meteor fireballs are electrical in origin. Confirmation that Extra/Very Low Frequency (ELF/VLF) electromagnetic radiation is produced by the fireball was obtained by Japanese researchers. Although the generation mechanism is not fully understood, studies of the Meteorite Observation and Recovery Project (MORP) and other fireball data indicate that interaction with the atmosphere is definitely responsible and the cut-off magnitude of -9 found for sustained electrophonic sounds is supported by theory. Brief bursts of ELF/VLF radiation may accompany flares or explosions of smaller fireballs, producing transient sounds near favorably placed observers. Laboratory studies show that mundane physical objects can respond to electrical excitation and produce audible sounds. Reports of electrophonic sounds should no longer be discarded. A catalog of over 300 reports relating to electrophonic phenomena associated with meteor fireballs, aurorae, and lightning was assembled. Many other reports have been cataloged in Russian. These may assist the full solution of the similar long-standing and contentious mystery of audible auroral displays.
Shekarriz, Alireza; Sheen, David M.
2000-01-01
According to the present invention, a method and apparatus rely upon tomographic measurement of the speed of sound and fluid velocity in a pipe. The invention provides a more accurate profile of velocity within flow fields where the speed of sound varies within the cross-section of the pipe. This profile is obtained by reconstruction of the velocity profile from the local speed of sound measurement simultaneously with the flow velocity. The method of the present invention is real-time tomographic ultrasonic Doppler velocimetry utilizing a to plurality of ultrasonic transmission and reflection measurements along two orthogonal sets of parallel acoustic lines-of-sight. The fluid velocity profile and the acoustic velocity profile are determined by iteration between determining a fluid velocity profile and measuring local acoustic velocity until convergence is reached.
Spectral Characteristics of Wake Vortex Sound During Roll-Up
NASA Technical Reports Server (NTRS)
Booth, Earl R., Jr. (Technical Monitor); Zhang, Yan; Wang, Frank Y.; Hardin, Jay C.
2003-01-01
This report presents an analysis of the sound spectra generated by a trailing aircraft vortex during its rolling-up process. The study demonstrates that a rolling-up vortex could produce low frequency (less than 100 Hz) sound with very high intensity (60 dB above threshold of human hearing) at a distance of 200 ft from the vortex core. The spectrum then drops o rapidly thereafter. A rigorous analytical approach has been adopted in this report to derive the spectrum of vortex sound. First, the sound pressure was solved from an alternative treatment of the Lighthill s acoustic analogy approach [1]. After the application of Green s function for free space, a tensor analysis was applied to permit the removal of the source term singularity of the wave equation in the far field. Consequently, the sound pressure is expressed in terms of the retarded time that indicates the time history and spacial distribution of the sound source. The Fourier transformation is then applied to the sound pressure to compute its spectrum. As a result, the Fourier transformation greatly simplifies the expression of the vortex sound pressure involving the retarded time, so that the numerical computation is applicable with ease for axisymmetric line vortices during the rolling-up process. The vortex model assumes that the vortex circulation is proportional to the time and the core radius is a constant. In addition, the velocity profile is assumed to be self-similar along the aircraft flight path, so that a benchmark vortex velocity profile can be devised to obtain a closed form solution, which is then used to validate the numerical calculations for other more realistic vortex profiles for which no closed form solutions are available. The study suggests that acoustic sensors operating at low frequency band could be profitably deployed for detecting the vortex sound during the rolling-up process.
Shortcuts to adiabaticity by counterdiabatic driving for trapped-ion displacement in phase space
An, Shuoming; Lv, Dingshun; del Campo, Adolfo; Kim, Kihwan
2016-01-01
The application of adiabatic protocols in quantum technologies is severely limited by environmental sources of noise and decoherence. Shortcuts to adiabaticity by counterdiabatic driving constitute a powerful alternative that speed up time-evolution while mimicking adiabatic dynamics. Here we report the experimental implementation of counterdiabatic driving in a continuous variable system, a shortcut to the adiabatic transport of a trapped ion in phase space. The resulting dynamics is equivalent to a ‘fast-motion video' of the adiabatic trajectory. The robustness of this protocol is shown to surpass that of competing schemes based on classical local controls and Fourier optimization methods. Our results demonstrate that shortcuts to adiabaticity provide a robust speedup of quantum protocols of wide applicability in quantum technologies. PMID:27669897
Shear Faulting and Adiabatic Heating: Experimental Results from Ice
NASA Astrophysics Data System (ADS)
Golding, N.; Schulson, E. M.; Renshaw, C. E.
2011-12-01
Ice exhibits two distinct modes of shear faulting (Golding et al. Acta Materialia, 2010;58:5043), namely frictional or Coulombic (C) faulting under moderate levels of confinement and non-frictional or plastic (P) faulting under high levels of confinement. The mechanisms governing C-faulting have previously been discussed in connection with the comb-crack model (Renshaw & Schulson Nature, 2001;412:897). Here we examine the physical process[es] that trigger P-faulting. Systematic experiments on laboratory grown granular and columnar polycrystalline ice loaded triaxially under a high degree of confinement at -10 oC to -40 oC at applied strain rates 10-5 s-1 to 10-1 s-1 trace the micro-mechanical evolution of P-faulting. Terminal failure is characterized by a sudden brittle-like loss in load bearing capacity, the development of a narrow shear band, comprised of recrystallized grains and oriented on a plane of maximum shear, and localized heating. Possible mechanisms considered to account for the localization include: 1) adiabatic heating, 2) localized material softening through a reduction in dislocation density caused by dynamic recrystallization and 3) a transition from power-law creep to grain-size-dependent diffusional creep as a result of grain refinement caused by dynamic recrystallization. Our results indicate that, although recrystallization develops dynamically during loading, microstructural development does not significantly affect shear localization in ice. Nor does it affect the character of the fault. The minimum levels of deformation required to generate faulting are found to be consistent with those predicted for adiabatic shear instability. The present observations suggest that under specific conditions adiabatic heating, rather than dynamic recrystallization, may lead to material instability and shear faulting.
Adiabatic quantum computing with spin qubits hosted by molecules.
Yamamoto, Satoru; Nakazawa, Shigeaki; Sugisaki, Kenji; Sato, Kazunobu; Toyota, Kazuo; Shiomi, Daisuke; Takui, Takeji
2015-01-28
A molecular spin quantum computer (MSQC) requires electron spin qubits, which pulse-based electron spin/magnetic resonance (ESR/MR) techniques can afford to manipulate for implementing quantum gate operations in open shell molecular entities. Importantly, nuclear spins, which are topologically connected, particularly in organic molecular spin systems, are client qubits, while electron spins play a role of bus qubits. Here, we introduce the implementation for an adiabatic quantum algorithm, suggesting the possible utilization of molecular spins with optimized spin structures for MSQCs. We exemplify the utilization of an adiabatic factorization problem of 21, compared with the corresponding nuclear magnetic resonance (NMR) case. Two molecular spins are selected: one is a molecular spin composed of three exchange-coupled electrons as electron-only qubits and the other an electron-bus qubit with two client nuclear spin qubits. Their electronic spin structures are well characterized in terms of the quantum mechanical behaviour in the spin Hamiltonian. The implementation of adiabatic quantum computing/computation (AQC) has, for the first time, been achieved by establishing ESR/MR pulse sequences for effective spin Hamiltonians in a fully controlled manner of spin manipulation. The conquered pulse sequences have been compared with the NMR experiments and shown much faster CPU times corresponding to the interaction strength between the spins. Significant differences are shown in rotational operations and pulse intervals for ESR/MR operations. As a result, we suggest the advantages and possible utilization of the time-evolution based AQC approach for molecular spin quantum computers and molecular spin quantum simulators underlain by sophisticated ESR/MR pulsed spin technology.
Optical force on atoms with periodic adiabatic rapid passage sequences
NASA Astrophysics Data System (ADS)
Miao, Xiyue
Adiabatic Rapid Passage (ARP) is a long-existing method to invert the population of a two-level nuclear spin system. Its extension to the optical domain necessitates a frequency chirped light pulse to interact with a two-level atom through dipole interaction. In this dissertation ARP processes for various pulse schemes and pulse parameters have been studied theoretically and experimentally. The non-adiabatic transition probability of ARP was quantified to characterize the efficiency of ARP for population transfer. Unanticipated regularities were found in the pulse parameter space. ARP sequences in periodic phase coherent counter-propagating light pulses can be used to produce large optical forces on atoms. The magnitude of the force is proportional to the pulse repetition rate. So the force can be much larger than the usual radiative force if the pulse repetition rate is much higher than the spontaneous emission rate. The behavior of the atoms in such periodic ARP fields without spontaneous emission is well described by a periodic Hamiltonian. By investigating the evolution of the Bloch vector on the Bloch sphere, we related the average optical force on atoms to the non-adiabatic transition probability of a single pulse. Syncopation time has to be introduced in the pulsing scheme to produce a directional force in the presence of spontaneous emission. Experimentally, we observed the force on He* atoms by the deflection of the atomic beam with periodic chirped pulses from counter-propagating pulse trains. The chirped pulse train was realized by synchronized phase and amplitude modulation of the light from a cw diode laser. The Fourier spectrum of the modulated light was monitored to guarantee the quality of the chirped pulses. The measured ARP forces are about half of the theoretical predictions. Not only have we shown that such forces are huge and robust, but we have also been able to map the forces in the two dimensional pulse parameter space. The force
Graefe, E. M.; Korsch, H. J.; Witthaut, D.
2006-01-15
We investigate the dynamics of a Bose-Einstein condensate in a triple-well trap in a three-level approximation. The interatomic interactions are taken into account in a mean-field approximation (Gross-Pitaevskii equation), leading to a nonlinear three-level model. Additional eigenstates emerge due to the nonlinearity, depending on the system parameters. Adiabaticity breaks down if such a nonlinear eigenstate disappears when the parameters are varied. The dynamical implications of this loss of adiabaticity are analyzed for two important special cases: A three-level Landau-Zener model and the stimulated Raman adiabatic passage (STIRAP) scheme. We discuss the emergence of looped levels for an equal-slope Landau-Zener model. The Zener tunneling probability does not tend to zero in the adiabatic limit and shows pronounced oscillations as a function of the velocity of the parameter variation. Furthermore we generalize the STIRAP scheme for adiabatic coherent population transfer between atomic states to the nonlinear case. It is shown that STIRAP breaks down if the nonlinearity exceeds the detuning.
Monaural Sound Localization Revisited
NASA Technical Reports Server (NTRS)
Wightman, Frederic L.; Kistler, Doris J.
1997-01-01
Research reported during the past few decades has revealed the importance for human sound localization of the so-called 'monaural spectral cues.' These cues are the result of the direction-dependent filtering of incoming sound waves accomplished by the pinnae. One point of view about how these cues are extracted places great emphasis on the spectrum of the received sound at each ear individually. This leads to the suggestion that an effective way of studying the influence of these cues is to measure the ability of listeners to localize sounds when one of their ears is plugged. Numerous studies have appeared using this monaural localization paradigm. Three experiments are described here which are intended to clarify the results of the previous monaural localization studies and provide new data on how monaural spectral cues might be processed. Virtual sound sources are used in the experiments in order to manipulate and control the stimuli independently at the two ears. Two of the experiments deal with the consequences of the incomplete monauralization that may have contaminated previous work. The results suggest that even very low sound levels in the occluded ear provide access to interaural localization cues. The presence of these cues complicates the interpretation of the results of nominally monaural localization studies. The third experiment concerns the role of prior knowledge of the source spectrum, which is required if monaural cues are to be useful. The results of this last experiment demonstrate that extraction of monaural spectral cues can be severely disrupted by trial-to-trial fluctuations in the source spectrum. The general conclusion of the experiments is that, while monaural spectral cues are important, the monaural localization paradigm may not be the most appropriate way to study their role.
Diabatic Versus Adiabatic Calculation of Torsion-Vibration Interactions
NASA Astrophysics Data System (ADS)
Hougen, Jon T.
2013-06-01
The introductory part of this talk will deal briefly with two historical topics: (i) use of the words adiabatic, nonadiabatic, and diabatic in thermodynamics and quantum mechanics, and (ii) application of diabatic and adiabatic ideas to vibrational energy level calculations for a pair of diatomic-molecule potential energy curves exhibiting an avoided crossing. The main part of the talk will be devoted to recent work with Li-Hong Xu and Ron Lees on how ab initio projected frequency calculations for small-amplitude vibrations along the large-amplitude internal rotation path in methanol can best be used to help guide experimental assignments and fits in the IR vibrational spectrum. The three CH stretching vibrations for CH_{3}OH can conveniently be represented as coefficients multiplying three different types of basis vibrations, i.e., as coefficients of: (i) the local mode C-H_i bond displacements δr_{i} for hydrogens H_{1}, H_{2} and H_{3} of the methyl top, (ii) symmetrized linear combinations of the three δr_{i} of species A_{1} oplus E in the permutation-inversion group G_{6} = C_{3v} appropriate for methanol, or (iii) symmetrized linear combinations of the three δr_{i} of species 2A_{1} oplus A_{2} in the permutation-inversion group G_{6}. In this talk, we will focus on diabatic and adiabatic computations for the A_{1} oplus E basis vibrations of case (ii) above. We will briefly explain how Jahn-Teller-like and Renner-Teller-like torsion-vibration interaction terms occurring in the potential energy expression in the diabatic calculation become torsion-vibration Coriolis interaction terms occurring in the kinetic energy expression of the adiabatic calculations, and also show how, for algebraically solvable parameter choices, the same energy levels are obtained from either calculation. A final conclusion as to which approach is computationally superior for the numerical data given in a quantum chemistry output file has not yet been arrived at.
Major Steps in the Discovery of Adiabatic Shear Bands
NASA Astrophysics Data System (ADS)
Dodd, Bradley; Walley, Stephen M.; Yang, Rong; Nesterenko, Vitali F.
2015-10-01
The standard story of the discovery of adiabatic shear bands is that it began with the American researchers Zener and Hollomon's famous 1944 paper where the phenomenon was first reported and named. However, a recent discovery by one of us (SMW) in the Cambridge University Library has shown that the phenomenon was discovered and described by a Russian researcher, V.P. Kravz-Tarnavskii, in 1928. A follow-up paper was published by two of his colleagues in 1935. Translations of the 1928 and 1935 papers may be found at http://arxiv.org/abs/1410.1353.
Adiabatic transport of qubits around a black hole
NASA Astrophysics Data System (ADS)
Viennot, David; Moro, Olivia
2017-03-01
We consider localized qubits evolving around a black hole following a quantum adiabatic dynamics. We develop a geometric structure (based on fibre bundles) permitting to describe the quantum states of a qubit and the spacetime geometry in a single framework. The quantum decoherence induced by the black hole on the qubit is analysed in this framework (the role of the dynamical and geometric phases in this decoherence is treated), especially for the quantum teleportation protocol when one qubit falls to the event horizon. A simple formula to compute the fidelity of the teleportation is derived. The case of a Schwarzschild black hole is analysed.
From Classical Nonlinear Integrable Systems to Quantum Shortcuts to Adiabaticity
NASA Astrophysics Data System (ADS)
Okuyama, Manaka; Takahashi, Kazutaka
2016-08-01
Using shortcuts to adiabaticity, we solve the time-dependent Schrödinger equation that is reduced to a classical nonlinear integrable equation. For a given time-dependent Hamiltonian, the counterdiabatic term is introduced to prevent nonadiabatic transitions. Using the fact that the equation for the dynamical invariant is equivalent to the Lax equation in nonlinear integrable systems, we obtain the counterdiabatic term exactly. The counterdiabatic term is available when the corresponding Lax pair exists and the solvable systems are classified in a unified and systematic way. Multisoliton potentials obtained from the Korteweg-de Vries equation and isotropic X Y spin chains from the Toda equations are studied in detail.
Relativistic blast waves in two dimensions. I - The adiabatic case
NASA Technical Reports Server (NTRS)
Shapiro, P. R.
1979-01-01
Approximate solutions are presented for the dynamical evolution of strong adiabatic relativistic blast waves which result from a point explosion in an ambient gas in which the density varies both with distance from the explosion center and with polar angle in axisymmetry. Solutions are analytical or quasi-analytical for the extreme relativistic case and numerical for the arbitrarily relativistic case. Some general properties of nonplanar relativistic shocks are also discussed, including the incoherence of spherical ultrarelativistic blast-wave fronts on angular scales greater than the reciprocal of the shock Lorentz factor, as well as the conditions for producing blast-wave acceleration.
Magnetic shielding for a spaceborne adiabatic demagnetization refrigerator (ADR)
NASA Technical Reports Server (NTRS)
Warner, Brent A.; Shirron, Peter J.; Castles, Stephen H.; Serlemitsos, Aristides T.
1991-01-01
The Goddard Space Flight Center has studied magnetic shielding for an adiabatic demagnetization refrigerator. Four types of shielding were studied: active coils, passive ferromagnetic shells, passive superconducting coils, and passive superconducting shells. The passive superconducting shells failed by allowing flux penetration. The other three methods were successful, singly or together. Experimental studies of passive ferromagnetic shielding are compared with calculations made using the Poisson Group of programs, distributed by the Los Alamos Accelerator Code Group of the Los Alamos National Laboratory. Agreement between calculation and experiment is good. The ferromagnetic material is a silicon iron alloy.
More bang for your buck: Super-adiabatic quantum engines
Campo, A. del; Goold, J.; Paternostro, M.
2014-01-01
The practical untenability of the quasi-static assumption makes any realistic engine intrinsically irreversible and its operating time finite, thus implying friction effects at short cycle times. An important technological goal is thus the design of maximally efficient engines working at the maximum possible power. We show that, by utilising shortcuts to adiabaticity in a quantum engine cycle, one can engineer a thermodynamic cycle working at finite power and zero friction. Our findings are illustrated using a harmonic oscillator undergoing a quantum Otto cycle. PMID:25163421
Non-Adiabatic Holonomic Quantum Gates in an atomic system
NASA Astrophysics Data System (ADS)
Azimi Mousolou, Vahid; Canali, Carlo M.; Sjoqvist, Erik
2012-02-01
Quantum computation is essentially the implementation of a universal set of quantum gate operations on a set of qubits, which is reliable in the presence of noise. We propose a scheme to perform robust gates in an atomic four-level system using the idea of non-adiabatic holonomic quantum computation proposed in [1]. The gates are realized by applying sequences of short laser pulses that drive transitions between the four energy levels in such a way that the dynamical phases vanish. [4pt] [1] E. Sjoqvist, D.M. Tong, B. Hessmo, M. Johansson, K. Singh, arXiv:1107.5127v2 [quant-ph
Metallization of nanofilms in strong adiabatic electric fields.
Durach, Maxim; Rusina, Anastasia; Kling, Matthias F; Stockman, Mark I
2010-08-20
We introduce an effect of metallization of dielectric nanofilms by strong, adiabatically varying electric fields. The metallization causes optical properties of a dielectric film to become similar to those of a plasmonic metal (strong absorption and negative permittivity at low optical frequencies). This is a quantum effect, which is exponentially size-dependent, occurring at fields on the order of 0.1 V/Å and pulse durations ranging from ∼1 fs to ∼10 ns for a film thickness of 3-10 nm.
Metallization of Nanofilms in Strong Adiabatic Electric Fields
NASA Astrophysics Data System (ADS)
Durach, Maxim; Rusina, Anastasia; Kling, Matthias F.; Stockman, Mark I.
2010-08-01
We introduce an effect of metallization of dielectric nanofilms by strong, adiabatically varying electric fields. The metallization causes optical properties of a dielectric film to become similar to those of a plasmonic metal (strong absorption and negative permittivity at low optical frequencies). This is a quantum effect, which is exponentially size-dependent, occurring at fields on the order of 0.1V/Å and pulse durations ranging from ˜1fs to ˜10ns for a film thickness of 3-10 nm.
Salt materials testing for a spacecraft adiabatic demagnetization refrigerator
NASA Astrophysics Data System (ADS)
Savage, M. L.; Kittel, P.; Roellig, T.
As part of a technology development effort to qualify adiabatic demagnetization refrigerators for use in a NASA spacecraft, such as the Space Infrared Telescope Facility, a study of low temperature characteristics, heat capacity and resistance to dehydration was conducted for different salt materials. This report includes results of testing with cerrous metaphosphate, several synthetic rubies, and chromic potassium alum (CPA). Preliminary results show that CPA may be suitable for long-term spacecraft use, provided that the salt is property encapsulated. Methods of salt pill construction and testing for all materials are discussed, as well as reliability tests. Also, the temperature regulation scheme and the test cryostat design are briefly discussed.
Optimized sympathetic cooling of atomic mixtures via fast adiabatic strategies
Choi, Stephen; Sundaram, Bala; Onofrio, Roberto
2011-11-15
We discuss fast frictionless cooling techniques in the framework of sympathetic cooling of cold atomic mixtures. It is argued that optimal cooling of an atomic species--in which the deepest quantum degeneracy regime is achieved--may be obtained by means of sympathetic cooling with another species whose trapping frequency is dynamically changed to maintain constancy of the Lewis-Riesenfeld adiabatic invariant. Advantages and limitations of this cooling strategy are discussed, with particular regard to the possibility of cooling Fermi gases to a deeper degenerate regime.
Salt materials testing for a spacecraft adiabatic demagnetization refrigerator
NASA Technical Reports Server (NTRS)
Savage, M. L.; Kittel, P.; Roellig, T.
1990-01-01
As part of a technology development effort to qualify adiabatic demagnetization refrigerators for use in a NASA spacecraft, such as the Space Infrared Telescope Facility, a study of low temperature characteristics, heat capacity and resistance to dehydration was conducted for different salt materials. This report includes results of testing with cerrous metaphosphate, several synthetic rubies, and chromic potassium alum (CPA). Preliminary results show that CPA may be suitable for long-term spacecraft use, provided that the salt is property encapsulated. Methods of salt pill construction and testing for all materials are discussed, as well as reliability tests. Also, the temperature regulation scheme and the test cryostat design are briefly discussed.
Propagation of laser pulses under conditions of adiabatic population transfer
Arkhipkin, V G; Manushkin, D V; Timofeev, V P
1998-12-31
A medium of three-level absorbing atoms is considered under conditions of adiabatic population transfer. A study is made of the characteristics of spatial propagation of two delayed (relative to one another) Gaussian pulses. It is shown that selective excitation of a two-photon resonant state with a near-unity probability is conserved over the length of a medium, which is considerably greater than the absorption length of a weak probe pulse in the absence of the second field. (physical basis of quantum electronics)
Stimulated Raman adiabatic passage in Tm{sup 3+}:YAG
Alexander, A. L.; Lauro, R.; Louchet, A.; Chaneliere, T.; Le Goueet, J. L.
2008-10-01
We report on the experimental demonstration of stimulated Raman adiabatic passage in a Tm{sup 3+}:YAG crystal. Tm{sup 3+}:YAG is a promising material for use in quantum information processing applications, but as yet there are few experimental investigations of coherent Raman processes in this material. We investigate the effect of inhomogeneous broadening and Rabi frequency on the transfer efficiency and the width of the two-photon spectrum. Simulations of the complete Tm{sup 3+}:YAG system are presented along with the corresponding experimental results.
Adiabatic invariants in stellar dynamics. 2: Gravitational shocking
NASA Technical Reports Server (NTRS)
Weinberg, Martin D.
1994-01-01
A new theory of gravitational shocking based on time-dependent perturbation theory shows that the changes in energy and angular momentum due to a slowly varying disturbance are not exponentially small for stellar dynamical systems in general. It predicts significant shock heating by slowly varying perturbations previously thought to be negligible according to the adiabatic criterion. The theory extends the scenarios traditionally computed only with the impulse approximation and is applicable to a wide class of disturbances. The approach is applied specifically to the problem of disk shocking of star clusters.
Modeling of the Adiabatic and Isothermal Methanation Process
NASA Astrophysics Data System (ADS)
Porubova, Jekaterina; Bazbauers, Gatis; Markova, Darja
2011-01-01
Increased use of biomass offers one of the ways to reduce anthropogenic impact on the environment. Using various biomass conversion processes, it is possible to obtain different types of fuels: • solid, e.g. bio-carbon; • liquid, e.g. biodiesel and ethanol; • gaseous, e.g. biomethane. Biomethane can be used in the transport and energy sector, and the total methane production efficiency can reach 65%. By modeling adiabatic and isothermal methanation processes, the most effective one from the methane production point of view is defined. Influence of the process parameters on the overall efficiency of the methane production is determined.
NASA Technical Reports Server (NTRS)
2000-01-01
Automated Analysis Corporation's COMET is a suite of acoustic analysis software for advanced noise prediction. It analyzes the origin, radiation, and scattering of noise, and supplies information on how to achieve noise reduction and improve sound characteristics. COMET's Structural Acoustic Foam Engineering (SAFE) module extends the sound field analysis capability of foam and other materials. SAFE shows how noise travels while airborne, how it travels within a structure, and how these media interact to affect other aspects of the transmission of noise. The COMET software reduces design time and expense while optimizing a final product's acoustical performance. COMET was developed through SBIR funding and Langley Research Center for Automated Analysis Corporation.
Sound from apollo rockets in space.
Cotten, D; Donn, W L
1971-02-12
Low-frequency sound has been recorded on at least two occasions in Bermuda with the passage of Apollo rocket vehicles 188 kilometers aloft. The signals, which are reminiscent of N-waves from sonic booms, are (i) horizontally coherent; (ii) have extremely high (supersonic) trace velocities across the tripartite arrays; (iii) have nearly identical appearance and frequencies; (iv) have essentially identical arrival times after rocket launch; and (v) are the only coherent signals recorded over many hours. These observations seem to establish that the recorded sound comes from the rockets at high elevation. Despite this high elevation, the values of surface pressure appear to be explainable on the basis of a combination of a kinetic theory approach to shock formation in rarefied atmospheres with established gas-dynamics shock theory.
Control of adiabatic light transfer in coupled waveguides with longitudinally varying detuning
NASA Astrophysics Data System (ADS)
Oukraou, Hassan; Vittadello, Laura; Coda, Virginie; Ciret, Charles; Alonzo, Massimo; Rangelov, Andon A.; Vitanov, Nikolay V.; Montemezzani, Germano
2017-02-01
We study adiabatic light transfer in systems of two coupled waveguides with spatially varying detuning of the propagation constants, providing an analogy to the quantum phenomena of rapid adiabatic passage (RAP) and two-state stimulated Raman adiabatic passage (two-state STIRAP). Experimental demonstration using a photoinduction technique confirms the robust and broadband character of the structures that act as broadband directional couplers and broadband beam splitters, respectively.
Shortcut to Adiabatic Passage in Two- and Three-Level Atoms
Chen Xi; Lizuain, I.; Muga, J. G.; Ruschhaupt, A.; Guery-Odelin, D.
2010-09-17
We propose a method to speed up adiabatic passage techniques in two-level and three-level atoms extending to the short-time domain their robustness with respect to parameter variations. It supplements or substitutes the standard laser beam setups with auxiliary pulses that steer the system along the adiabatic path. Compared to other strategies, such as composite pulses or the original adiabatic techniques, it provides a fast and robust approach to population control.
Determining the Complexity of the Quantum Adiabatic Algorithm using Quantum Monte Carlo Simulations
2012-12-18
efficiently a quantum computer could solve optimization problems using the quantum adiabatic algorithm (QAA). Comparisons were made with a classical...Park, NC 27709-2211 15. SUBJECT TERMS Quantum Adiabatic Algorithm , Optimization, Monte Carlo, quantum computer, satisfiability problems, spin glass... quantum adiabatic algorithm (QAA). Comparisons were made with a classical heuristic algorithm , WalkSAT. A preliminary study was also made to see if the
Shortcut to adiabatic control of soliton matter waves by tunable interaction
Li, Jing; Sun, Kun; Chen, Xi
2016-01-01
We propose a method for shortcut to adiabatic control of soliton matter waves in harmonic traps. The tunable interaction controlled by Feshbach resonance is inversely designed to achieve fast and high-fidelity compression of soliton matter waves as compared to the conventional adiabatic compression. These results pave the way to control the nonlinear dynamics for matter waves and optical solitons by using shortcuts to adiabaticity. PMID:28009007
Sehmel, G.A.
1984-03-01
Dry deposition velocities are very difficult to predict accurately. In this article, reported values of dry deposition velocities are summarized. This summary includes values from the literature on field measurements of gas and particle dry deposition velocities, and the uncertainties inherent in extrapolating field results to predict dry deposition velocities are discussed. A new method is described for predicting dry deposition velocity using a least-squares correlation of surface mass transfer resistances evaluated in wind tunnel experiments. 14 references, 4 figures, 1 table.
Singularity of the time-energy uncertainty in adiabatic perturbation and cycloids on a Bloch sphere.
Oh, Sangchul; Hu, Xuedong; Nori, Franco; Kais, Sabre
2016-02-26
Adiabatic perturbation is shown to be singular from the exact solution of a spin-1/2 particle in a uniformly rotating magnetic field. Due to a non-adiabatic effect, its quantum trajectory on a Bloch sphere is a cycloid traced by a circle rolling along an adiabatic path. As the magnetic field rotates more and more slowly, the time-energy uncertainty, proportional to the length of the quantum trajectory, calculated by the exact solution is entirely different from the one obtained by the adiabatic path traced by the instantaneous eigenstate. However, the non-adiabatic Aharonov-Anandan geometric phase, measured by the area enclosed by the exact path, approaches smoothly the adiabatic Berry phase, proportional to the area enclosed by the adiabatic path. The singular limit of the time-energy uncertainty and the regular limit of the geometric phase are associated with the arc length and arc area of the cycloid on a Bloch sphere, respectively. Prolate and curtate cycloids are also traced by different initial states outside and inside of the rolling circle, respectively. The axis trajectory of the rolling circle, parallel to the adiabatic path, is shown to be an example of transitionless driving. The non-adiabatic resonance is visualized by the number of cycloid arcs.
Wu, Jin-Lei; Ji, Xin; Zhang, Shou
2017-01-01
We propose a dressed-state scheme to achieve shortcuts to adiabaticity in atom-cavity quantum electrodynamics for speeding up adiabatic two-atom quantum state transfer and maximum entanglement generation. Compared with stimulated Raman adiabatic passage, the dressed-state scheme greatly shortens the operation time in a non-adiabatic way. By means of some numerical simulations, we determine the parameters which can guarantee the feasibility and efficiency both in theory and experiment. Besides, numerical simulations also show the scheme is robust against the variations in the parameters, atomic spontaneous emissions and the photon leakages from the cavity.
Singularity of the time-energy uncertainty in adiabatic perturbation and cycloids on a Bloch sphere
Oh, Sangchul; Hu, Xuedong; Nori, Franco; Kais, Sabre
2016-01-01
Adiabatic perturbation is shown to be singular from the exact solution of a spin-1/2 particle in a uniformly rotating magnetic field. Due to a non-adiabatic effect, its quantum trajectory on a Bloch sphere is a cycloid traced by a circle rolling along an adiabatic path. As the magnetic field rotates more and more slowly, the time-energy uncertainty, proportional to the length of the quantum trajectory, calculated by the exact solution is entirely different from the one obtained by the adiabatic path traced by the instantaneous eigenstate. However, the non-adiabatic Aharonov- Anandan geometric phase, measured by the area enclosed by the exact path, approaches smoothly the adiabatic Berry phase, proportional to the area enclosed by the adiabatic path. The singular limit of the time-energy uncertainty and the regular limit of the geometric phase are associated with the arc length and arc area of the cycloid on a Bloch sphere, respectively. Prolate and curtate cycloids are also traced by different initial states outside and inside of the rolling circle, respectively. The axis trajectory of the rolling circle, parallel to the adiabatic path, is shown to be an example of transitionless driving. The non-adiabatic resonance is visualized by the number of cycloid arcs. PMID:26916031
Turbulent boundary-layer velocity profiles on a nonadiabatic at Mach number 6.5
NASA Technical Reports Server (NTRS)
Keener, E. R.; Hopkins, E. J.
1972-01-01
Velocity profiles were obtained from pitot-pressure and total-temperature measurements within a turbulent boundary layer on a large sharp-edged flat plate. Momentum-thickness Reynolds number ranged from 2590 to 8860 and wall-to-adiabatic-wall temperature ratios ranged from 0.3 to 0.5. Measurements were made both with and without boundary layer trips. Five methods are evaluated for correlating the measured velocity profiles with the incompressible law-of-the-wall and the velocity defect law. The mixing-length generalization of Van Driest gives the best correlation.
ERIC Educational Resources Information Center
Manpower Administration (DOL), Washington, DC. Job Corps.
This self-study program for high-school level contains lessons on: Speed, Acceleration, and Velocity; Force, Mass, and Distance; Types of Motion and Rest; Electricity and Magnetism; Electrical, Magnetic, and Gravitational Fields; The Conservation and Conversion of Matter and Energy; Simple Machines and Work; Gas Laws; Principles of Heat Engines;…
Robust quantum logic in neutral atoms via adiabatic Rydberg dressing
Keating, Tyler; Cook, Robert L.; Hankin, Aaron M.; Jau, Yuan -Yu; Biedermann, Grant W.; Deutsch, Ivan H.
2015-01-28
We study a scheme for implementing a controlled-Z (CZ) gate between two neutral-atom qubits based on the Rydberg blockade mechanism in a manner that is robust to errors caused by atomic motion. By employing adiabatic dressing of the ground electronic state, we can protect the gate from decoherence due to random phase errors that typically arise because of atomic thermal motion. In addition, the adiabatic protocol allows for a Doppler-free configuration that involves counterpropagating lasers in a σ_{+}/σ_{-} orthogonal polarization geometry that further reduces motional errors due to Doppler shifts. The residual motional error is dominated by dipole-dipole forces acting on doubly-excited Rydberg atoms when the blockade is imperfect. As a result, for reasonable parameters, with qubits encoded into the clock states of ^{133}Cs, we predict that our protocol could produce a CZ gate in < 10 μs with error probability on the order of 10^{-3}.
Breakdown of adiabatic electron behavior in expanding magnetic fields
NASA Astrophysics Data System (ADS)
Lichko, Emily; Egedal, Jan; Daughton, William
2015-11-01
During magnetic reconnection the incoming magnetic flux tubes expand in the inflow region. If this expansion is sufficiently slow the results are well described by a previously developed adiabatic model. Using kinetic simulations in a simple geometry and applying rapid magnetic perturbations, this study investigates the point at which the adiabatic assumption fails. To this end a 2D VPIC simulation was constructed, where the magnetic field in a uniform plasma is perturbed by externally driven currents. By varying the onset speed of the magnetic perturbation and the electron thermal speed, we found a sharp threshold at which this model breaks down. We believe that this point is determined by the time of the magnetic pumping compared to the electron transit time through the region, i.e. ω ~ Ḃ / B ~vthe / L . This threshold was also characterized by the launching of Whistler waves and with time domain structures, such as electron holes and double layers, which agree with those seen during magnetic reconnection and may relate to similar structures in the Van Allen Belts. NSF GEM award 1405166 and NASA grant NNX14AC68G.
Robust quantum logic in neutral atoms via adiabatic Rydberg dressing
Keating, Tyler; Cook, Robert L.; Hankin, Aaron M.; ...
2015-01-28
We study a scheme for implementing a controlled-Z (CZ) gate between two neutral-atom qubits based on the Rydberg blockade mechanism in a manner that is robust to errors caused by atomic motion. By employing adiabatic dressing of the ground electronic state, we can protect the gate from decoherence due to random phase errors that typically arise because of atomic thermal motion. In addition, the adiabatic protocol allows for a Doppler-free configuration that involves counterpropagating lasers in a σ+/σ- orthogonal polarization geometry that further reduces motional errors due to Doppler shifts. The residual motional error is dominated by dipole-dipole forces actingmore » on doubly-excited Rydberg atoms when the blockade is imperfect. As a result, for reasonable parameters, with qubits encoded into the clock states of 133Cs, we predict that our protocol could produce a CZ gate in < 10 μs with error probability on the order of 10-3.« less
Schedule path optimization for adiabatic quantum computing and optimization
NASA Astrophysics Data System (ADS)
Zeng, Lishan; Zhang, Jun; Sarovar, Mohan
2016-04-01
Adiabatic quantum computing and optimization have garnered much attention recently as possible models for achieving a quantum advantage over classical approaches to optimization and other special purpose computations. Both techniques are probabilistic in nature and the minimum gap between the ground state and first excited state of the system during evolution is a major factor in determining the success probability. In this work we investigate a strategy for increasing the minimum gap and success probability by introducing intermediate Hamiltonians that modify the evolution path between initial and final Hamiltonians. We focus on an optimization problem relevant to recent hardware implementations and present numerical evidence for the existence of a purely local intermediate Hamiltonian that achieve the optimum performance in terms of pushing the minimum gap to one of the end points of the evolution. As a part of this study we develop a convex optimization formulation of the search for optimal adiabatic schedules that makes this computation more tractable, and which may be of independent interest. We further study the effectiveness of random intermediate Hamiltonians on the minimum gap and success probability, and empirically find that random Hamiltonians have a significant probability of increasing the success probability, but only by a modest amount.
The effect of adiabaticity on strongly quenched Bose Einstein Condensates
NASA Astrophysics Data System (ADS)
Ling, Hong; Kain, Ben
2015-05-01
We study the properties of a Bose-Einstein condensate following a deep quench to a large scattering length during which the condensate fraction nc changes with time. We construct a closed set of equations that highlight the role of the adiabaticity or equivalently, dnc/dt, the rate change of nc, which is to induce an (imaginary) effective interaction between quasiparticles. We show analytically that such a system supports a steady state characterized by a constant condensate density and a steady but periodically changing momentum distribution, whose time average is described exactly by the generalized Gibbs ensemble. We discuss how the nc -induced effective interaction, which cannot be ignored on the grounds of the adiabatic approximation for modes near the gapless Goldstone mode, can significantly affect condensate populations and Tan's contact for a Bose gas that has undergone a deep quench. In particular, we find that even when the Bose gas is quenched to unitarity, nc(t) does not completely deplete, approaching, instead, to a steady state with a finite condensate fraction. ITAMP, Harvard-Smithsonian Center for Astrophysics; KITP, University of Santa Barbara.
Highly parallel implementation of non-adiabatic Ehrenfest molecular dynamics
NASA Astrophysics Data System (ADS)
Kanai, Yosuke; Schleife, Andre; Draeger, Erik; Anisimov, Victor; Correa, Alfredo
2014-03-01
While the adiabatic Born-Oppenheimer approximation tremendously lowers computational effort, many questions in modern physics, chemistry, and materials science require an explicit description of coupled non-adiabatic electron-ion dynamics. Electronic stopping, i.e. the energy transfer of a fast projectile atom to the electronic system of the target material, is a notorious example. We recently implemented real-time time-dependent density functional theory based on the plane-wave pseudopotential formalism in the Qbox/qb@ll codes. We demonstrate that explicit integration using a fourth-order Runge-Kutta scheme is very suitable for modern highly parallelized supercomputers. Applying the new implementation to systems with hundreds of atoms and thousands of electrons, we achieved excellent performance and scalability on a large number of nodes both on the BlueGene based ``Sequoia'' system at LLNL as well as the Cray architecture of ``Blue Waters'' at NCSA. As an example, we discuss our work on computing the electronic stopping power of aluminum and gold for hydrogen projectiles, showing an excellent agreement with experiment. These first-principles calculations allow us to gain important insight into the the fundamental physics of electronic stopping.
Enhanced Diffusion Weighting Generated by Selective Adiabatic Pulse Trains
Sun, Ziqi; Bartha, Robert
2007-01-01
A theoretical description and experimental validation of the enhanced diffusion weighting generated by selective adiabatic full passage (AFP) pulse trains is provided. Six phantoms (Ph-1 to Ph-6) were studied on a 4T Varian/Siemens whole body MRI system. Phantoms consisted of 2.8 cm diameter plastic tubes containing a mixture of 10 μm ORGASOL polymer beads and 2 mM Gd-DTPA dissolved in 5% agar (Ph-1) or nickel(II) ammonium sulphate hexahydrate doped (56.3 mM – 0.8 mM) water solutions (Ph-2 to Ph-6). A customized localization by adiabatic selective refocusing (LASER) sequence containing slice selective AFP pulse trains and pulsed diffusion gradients applied in the phase encoding direction was used to measure 1H2O diffusion. The b-value associated with the LASER sequence was derived using the Bloch-Torrey equation. The apparent diffusion coefficients measured by LASER were comparable to those measured by a conventional pulsed gradient spin-echo (PGSE) sequence for all phantoms. Image signal intensity increased in Ph-1 and decreased in Ph-2 – Ph-6 as AFP pulse train length increased while maintaining a constant echo-time. These experimental results suggest that such AFP pulse trains can enhance contrast between regions containing microscopic magnetic susceptibility variations and homogeneous regions in which dynamic dephasing relaxation mechanisms are dominant. PMID:17600741
The 0.1K bolometers cooled by adiabatic demagnetization
NASA Technical Reports Server (NTRS)
Roellig, T.; Lesyna, L.; Kittel, P.; Werner, M.
1983-01-01
The most straightforward way of reducing the noise equivalent power of bolometers is to lower their operating temperature. We have been exploring the possibility of using conventionally constructed bolometers at ultra-low temperatures to achieve NEP's suitable to the background environment of cooled space telescopes. We have chosen the technique of adiabatic demagnetization of a paramagnetic salt as a gravity independent, compact, and low power way to achieve temperatures below pumped He-3 (0.3 K). The demagnetization cryostat we used was capable of reaching temperatures below 0.08 K using Chromium Potassium Alum as a salt from a starting temperature of 1.5 K and a starting magnetic field of 30,000 gauss. Computer control of the magnetic field decay allowed a temperature of 0.2 K to be maintained to within 0.5 mK over a time period exceeding 14 hours. The refrigerator duty cycle was over 90 percent at this temperature. The success of these tests has motivated us to construct a more compact portable adiabatic demagnetization cryostat capable of bolometer optical tests and use at the 5m Hale telescope at 1mm wavelengths.
Adiabatic cooling of the artificial Porcupine plasma jet
NASA Astrophysics Data System (ADS)
Ruizhin, Iu. Ia.; Treumann, R. A.; Bauer, O. H.; Moskalenko, A. M.
1987-01-01
Measurements of the plasma density obtained during the interaction of the artificial plasma jet, fired into the ionosphere with the body of the Porcupine main payload, have been analyzed for times when there was a well-developed wake effect. Using wake theory, the maximum temperature of the quasi-neutral xenon ion beam has been determined for an intermediate distance from the ion beam source when the beam has left the diamagnetic region but is still much denser than the ionospheric background plasma. The beam temperature is found to be about 4 times less than the temperature at injection. This observation is very well explained by adiabatic cooling of the beam during its initial diamagnetic and current-buildup phases at distances r smaller than 10 m. Outside this region, the beam conserves the temperature achieved. The observation proves that the artificial plasma jet passes through an initial gas-like diamagnetic phase restricted to the vicinity of the beam source, where it expands adiabatically. Partial cooling also takes place outside the diamagnetic region where the beam current still builds up. The observations also support a recently developed current-closure model of the quasi-neutral ion beam.
Adiabatic-nuclei calculations of positron scattering from molecular hydrogen
NASA Astrophysics Data System (ADS)
Zammit, Mark C.; Fursa, Dmitry V.; Savage, Jeremy S.; Bray, Igor; Chiari, Luca; Zecca, Antonio; Brunger, Michael J.
2017-02-01
The single-center adiabatic-nuclei convergent close-coupling method is used to investigate positron collisions with molecular hydrogen (H2) in the ground and first vibrationally excited states. Cross sections are presented over the energy range from 1 to 1000 eV for elastic scattering, vibrational excitation, total ionization, and the grand total cross section. The present adiabatic-nuclei positron-H2 scattering length is calculated as A =-2.70 a0 for the ground state and A =-3.16 a0 for the first vibrationally excited state. The present elastic differential cross sections are also used to "correct" the low-energy grand total cross-section measurements of the Trento group [A. Zecca et al., Phys. Rev. A 80, 032702 (2009), 10.1103/PhysRevA.80.032702] for the forward-angle-scattering effect. In general, the comparison with experiment is good. By performing convergence studies, we estimate that our Rm=1.448 a0 fixed-nuclei results are converged to within ±5 % for the major scattering integrated cross sections.
Breakdown of the adiabatic Born-Oppenheimer approximation in graphene
NASA Astrophysics Data System (ADS)
Pisana, Simone; Lazzeri, Michele; Casiraghi, Cinzia; Novoselov, Kostya S.; Geim, A. K.; Ferrari, Andrea C.; Mauri, Francesco
2007-03-01
The adiabatic Born-Oppenheimer approximation (ABO) has been the standard ansatz to describe the interaction between electrons and nuclei since the early days of quantum mechanics. ABO assumes that the lighter electrons adjust adiabatically to the motion of the heavier nuclei, remaining at any time in their instantaneous ground state. ABO is well justified when the energy gap between ground and excited electronic states is larger than the energy scale of the nuclear motion. In metals, the gap is zero and phenomena beyond ABO (such as phonon-mediated superconductivity or phonon-induced renormalization of the electronic properties) occur. The use of ABO to describe lattice motion in metals is, therefore, questionable. In spite of this, ABO has proved effective for the accurate determination of chemical reactions, molecular dynamics and phonon frequencies in a wide range of metallic systems. Here, we show that ABO fails in graphene. Graphene, recently discovered in the free state, is a zero-bandgap semiconductor that becomes a metal if the Fermi energy is tuned applying a gate voltage, Vg. This induces a stiffening of the Raman G peak that cannot be described within ABO.
ERIC Educational Resources Information Center
Robertson, Laura; Meyer, John R.
2010-01-01
Differences in insect morphology and movement during singing provide a fascinating opportunity for students to investigate insects while learning about the characteristics of sound. In the activities described here, students use a free online computer software program to explore the songs of the major singing insects and experiment with making…
ERIC Educational Resources Information Center
Fleischman, Paul
1986-01-01
Claims that in metrical prose, rhythm can convey sense or express and underline what a writer is saying, and sound can be exploited to add a strong aural element that provides pleasure to the ears over and above the pleasure given by the sense of story. (SRT)