Attenuation operators and complex wave velocities for scattering in random media

1996 ◽  
Vol 148 (1-2) ◽  
pp. 269-285 ◽  
Author(s):  
Y. Fang ◽  
G. M�ller
Keyword(s):  
Random Media ◽  
Wave Velocities ◽  
Complex Wave

Anisotropy in sedimentary rocks modeled as random media

Geophysics ◽  
1992 ◽  
Vol 57 (4) ◽  
pp. 564-576 ◽  
Author(s):  
Claudia Kerner
Keyword(s):  
Random Media ◽  
Transversely Isotropic ◽  
Anisotropic Behavior ◽  
S Wave ◽  
Elastic Parameters ◽  
Transversely Isotropic Medium ◽  
Long Wavelength ◽  
Wave Velocities ◽  
Wavelength Scale ◽  
Averaging Techniques

The anisotropic behavior to be expected from various types of sediments is investigated by considering them as laminated media, with randomly varying velocity depth distributions. Two different stochastic processes are used to model transitional and cyclic layering. The kinematics of waves propagating through the laminated media is studied by evaluating overall elastic parameters of the transversely isotropic medium in the long wavelength limit using averaging techniques. Models with strong velocity fluctuations and high correlation between P‐ and S‐wave velocities exhibit significant anisotropy, comparable in magnitude to field and laboratory measurements. Elastic wavefields for the stochastic models were computed and the results were compared with analytical and numerical results for homogeneous anisotropic media computed with the derived overall parameters. The wavefield modeling shows that anisotropy and scattering are not simply effects influencing waves on the opposite ends of the wavelength scale but that there is an intermediate range where both effects profoundly influence wave propagation.

Manifolds in random media: beyond the variational approximation

1994 ◽  
Vol 4 (1) ◽  
pp. 87-100 ◽  
Author(s):  
Yadin Y. Goldschmidt
Keyword(s):  
Random Media ◽  
Variational Approximation

Random media with temperature controlled connectivity

1992 ◽  
Vol 2 (5) ◽  
pp. 503-510 ◽  
Author(s):  
F. Carmona ◽  
E. Valot ◽  
L. Servant ◽  
M. Ricci
Keyword(s):  
Random Media ◽  
Temperature Controlled

Investigation of particulate systems using optical pathlength spectroscopy

2000 ◽  
Vol 627 ◽  
Author(s):  
Gabriel Popescu ◽  
Aristide Dogariu
Keyword(s):  
Path Length ◽  
Random Media ◽  
Michelson Interferometer ◽  
Industrial Process ◽  
Optical Path Length ◽  
Industrial Applications ◽  
Optical Path ◽  
Interference Signal ◽  
Optical Length ◽  
Reference Mirror

ABSTRACTIn many industrial applications involving granular media, knowledge about the structural transformations suffered during the industrial process is desirable. Optical techniques are noninvasive, fast, and versatile tools for monitoring such transformations. We have recently introduced optical path-length spectroscopy as a new technique for random media investigation. The principle of the method is to use a partially coherent source in a Michelson interferometer, where the fields from a reference mirror and the sample are combined to obtain an interference signal. When the system under investigation is a multiple-scattering medium, by tuning the optical length of the reference arm, the optical path-length probability density of light backscattered from the sample is obtained. This distribution carries information about the structural details of the medium. In the present paper, we apply the technique of optical path-length spectroscopy to investigate inhomogeneous distributions of particulate dielectrics such as ceramics and powders. The experiments are performed on suspensions of systems with different solid loads, as well as on powders and suspensions of particles with different sizes. We show that the methodology is highly sensitive to changes in volume concentration and particle size and, therefore, it can be successfully used for real-time monitoring. In addition, the technique is fiber optic-based and has all the advantages associated with the inherent versatility.

Propagation and Reflection of Plane Waves in a Rotating Magneto-Elastic Fibre-Reinforced Semi Space with Surface Stress

2020 ◽  
Vol 22 (4) ◽  
pp. 939-958
Author(s):  
Indrajit Roy ◽  
D. P. Acharya ◽  
Sourav Acharya
Keyword(s):  
Surface Stress ◽  
Incident Angle ◽  
Plane Waves ◽  
Three Dimensional ◽  
Elastic Fibre ◽  
Amplitude Ratios ◽  
Governing Equations ◽  
Rotation Surface ◽  
Wave Velocities ◽  
Magnetic Field Rotation

AbstractThe present paper investigates the propagation of quasi longitudinal (qLD) and quasi transverse (qTD) waves in a magneto elastic fibre-reinforced rotating semi-infinite medium. Reflections of waves from the flat boundary with surface stress have been studied in details. The governing equations have been used to obtain the polynomial characteristic equation from which qLD and qTD wave velocities are found. It is observed that both the wave velocities depend upon the incident angle. After imposing the appropriate boundary conditions including surface stress the resultant amplitude ratios for the total displacements have been obtained. Numerically simulated results have been depicted graphically by displaying two and three dimensional graphs to highlight the influence of magnetic field, rotation, surface stress and fibre-reinforcing nature of the material medium on the propagation and reflection of plane waves.

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