Results 261 to 270 of about 394,289 (310)

Group velocity of light in biaxial crystals

Applied Optics, 2021
Based on the wave vector surface, we have derived the analytical expressions for the group velocity of light traveling in an optically biaxial crystal in an arbitrary direction. Our formulas are in terms of either the wave vector direction or the ray direction.
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Group velocity of whistlers

Journal of Geophysical Research, 1976
The dispersion relation of waves in a cold magnetoplasma can be given in the form ..sigma../sub i//sub 0/ /sub p/ Au(k) ..omega..'=0, where ..omega.. is the frequency and the coefficients A/sub i/ are functions of the wave vector k. The group velocity V/sub g/ can be expressed as V/sub g/=-..sigma../sub i//sub 0/ p (partialA/sub i//partialk) ..omega ...
K. M. Johansen, Egil Leer
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Measurements of phase velocity and group velocity in human calcaneus

Ultrasound in Medicine & Biology, 2000
Ultrasonic velocity in calcaneus correlates highly with bone mineral density, which is a good predictor of osteoporotic fracture risk. Several commercial bone sonometers perform a velocity measurement based on the transit time of a broadband pulse to assess skeletal status.
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Dispersion, group velocity, and multisymplectic discretizations

Mathematics and Computers in Simulation, 2009
The authors consider the dispersive properties of multisymplectic discretization of linear wave and the sine Gordon equations. In particular a leapfrog in space and time scheme and the Preissman box scheme is considered. They find the numerical dispersions are monotonic and that the sign of the group velocity is preserved but for the nonsymplectic ...
Schober, C. M., Wlodarczyk, T. H.
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The Group Velocity Approximation

2009
Because of its mathematical simplicity and direct physical interpretation, the group velocity approximation has gained widespread use in the physics, engineering, and mathematical science communitites. However, the fundamental assumptions that are used to obtain this description are violated when either the loss component of the material dispersion ...
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A note on group velocity

Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences, 1977
Abstract By a simpler proof than was previously available (see, for example Rayleigh 1877, Lighthill 1960) it is shown that the mean energy flux velocity vector for a single infinite train of elliptically polarized harmonic small amplitude plane waves propagating in a homogeneous conservative, dispersive system is equal to the group ...
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A note on group velocity

Journal of Fluid Mechanics, 1960
The kinematic approach to group velocity given in Lighthill & Whitham (1955) for one-dimensional waves is extended to cover the general three-dimensional case. The ideas have particular bearing on the theory developed by Ursell (1960) for treating steady wave patterns on non-uniform steady fluid flows.Although this note was written in ignorance of ...
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On the phase velocity and group velocity of guided waves

Journal of Mathematical Physics, 1973
Relations between the phase velocity and group velocity of guided waves in homogeneous media and the restrictions under which they can be generalized to inhomogeneous media are discussed. Dirichlet, Neumann, and mixed boundary conditions are considered, including the case of frequency dependent media and boundary conditions.
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Superluminal group velocities and information transfer

Physics Letters A, 1996
zbMATH Open Web Interface contents unavailable due to conflicting licenses.
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Effect of CO2 on coal P-wave velocity under triaxial stress

International Journal of Mining Science and Technology, 2022
Jianhong Kang, Youpai Wang, Fubao Zhou   +2 more
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