Volume Dependence of the Longitudinal Sound Velocity in hcpHe4Single Crystals

1970 ◽  
Vol 24 (8) ◽  
pp. 365-367 ◽  
Author(s):  
R. Wanner ◽  
J. P. Franck
Keyword(s):  
Sound Velocity ◽  
Volume Dependence ◽  
Longitudinal Sound Velocity

FIRST-PRINCIPLES INVESTIGATION OF THE ELECTRONIC, ELASTIC AND THERMODYNAMIC PROPERTIES OF SUPERCONDUCTING MgB2

2014 ◽  
Vol 28 (10) ◽  
pp. 1450057 ◽  
Author(s):  
HONGYING LU ◽  
JIANPING LONG ◽  
LIJUN YANG ◽  
WEN HUANG
Keyword(s):  
Thermal Conductivity ◽  
Sound Velocity ◽  
Debye Temperature ◽  
First Principles ◽  
Function Theory ◽  
Density Function Theory ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Anisotropy Index ◽  
Longitudinal Sound Velocity

The electronic structure, elastic properties, Debye temperature and thermal conductivity of MgB 2 are investigated by using the first-principles density function theory within the generalized gradient approximation (GGA). The calculated elastic constants indicate that the MgB 2 is mechanically stable. The shear modulus, Young's modulus, Poisson's ratio, σ, the ratio B/G and universal anisotropy index are also calculated. Finally, the averaged sound velocity, longitudinal sound velocity, transverse sound velocity, Debye temperature and thermal conductivity are obtained.

The Interaction of Longitudinally Polarized Vibrations in an Isotropic Dielectric

1961 ◽  
Vol 57 (1) ◽  
pp. 86-95 ◽  
Author(s):  
S. Simons
Keyword(s):  
Relaxation Time ◽  
Sodium Chloride ◽  
Sound Velocity ◽  
Theoretical Treatment ◽  
Interaction Theory ◽  
Phonon Interaction ◽  
Longitudinal Sound Velocity ◽  
Solid Argon

ABSTRACTA theoretical treatment is given of the relaxation time for the absorption of longitudinally polarized vibrations in an isotropie medium. Employing standard phonon interaction theory, the relaxation time is obtained in terms of certain integrals, depending parametrically on the ratio of transverse to longitudinal sound velocity. These integrals are evaluated numerically over the range which this ratio takes in practice. The results are applied to a consideration of solid argon, sodium chloride and germanium.

scholarly journals Bioinspired Low-Frequency Material Characterisation

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
C. Hopper ◽  
S. Assous ◽  
P. B. Wilkinson ◽  
D. A. Gunn ◽  
P. D. Jackson ◽  
...  
Keyword(s):  
Sound Velocity ◽  
Medical Physics ◽  
Low Frequency ◽  
High Sensitivity ◽  
Prediction Errors ◽  
Low Frequencies ◽  
Longitudinal Sound Velocity ◽  
Velocity Prediction ◽  
Thickness Measurements

New-coded signals, transmitted by high-sensitivity broadband transducers in the 40–200 kHz range, allow subwavelength material discrimination and thickness determination of polypropylene, polyvinylchloride, and brass samples. Frequency domain spectra enable simultaneous measurement of material properties including longitudinal sound velocity and the attenuation constant as well as thickness measurements. Laboratory test measurements agree well with model results, with sound velocity prediction errors of less than 1%, and thickness discrimination of at least wavelength/15. The resolution of these measurements has only been matched in the past through methods that utilise higher frequencies. The ability to obtain the same resolution using low frequencies has many advantages, particularly when dealing with highly attenuating materials. This approach differs significantly from past biomimetic approaches where actual or simulated animal signals have been used and consequently has the potential for application in a range of fields where both improved penetration and high resolution are required, such as nondestructive testing and evaluation, geophysics, and medical physics.

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