in this paper the propagation of harmonic plane waves in a homogeneous anisotropic magneto-piezothermoelastic diffusive body with fractional order derivative is studied. the governing equations for a homogeneous transversely isotropic body in the context of the theory of thermoelasticity with diffusion given by sherief et al. [1] are considered as a special case. it is found that three types of...

Single-walled carbon nanotube bundles dispersed in a highly polar fluid are found to agglomerate into a porous structure when exposed to low levels of laser radiation. The phototunable nanoscale porous structures provide an unusual way to control the acoustic properties of the suspension. Despite the high sound speed of the nanotubes, the measured speed of longitudinal-acoustic waves in the sus...

As seismic reflection data become more prevalent as input for quantitative environmental and engineering studies, there is a growing need to assess and improve the accuracy of reflection processing methodologies. It is common for compressional-wave velocities to increase by a factor of four or more where shallow, unconsolidated sediments change from a dry or partially watersaturated regime to f...

Surface wave dispersion curve inversion is a challenging problem for linear inversion procedures due to its highly non-linear nature and to the large numbers of local minima and maxima of the objective function (multi-modality). In order to improve the reliability of the inversion results, we implemented and tested a two-step inversion scheme based on Genetic Algorithms (GAs). The proposed sche...

Understanding the relationship between compressional and shear wave velocities their anisotropic characteristics in self-resourcing reservoir shales is of considerable interest for petrophysical, geophysical, geomechanical applications unconventional resources exploration production. We compile laboratory measurements on ultrasonic velocity known shale reservoirs worldwide. Their propagating ve...

An acoustic wave pissing through a material has its velocity changed when stress is applied. This is due to changes in the third order elastic constant and the density of the material. By using a small diameter beam or a focused beam Incident on a metal and reflected from both its front and back surfaces, It is possible to measure the difference in phase of the two reflected waves; the beam Its...

S U M M A R Y This paper presents a comparison of ray-theoretical and finite-frequency traveltime tomography for compressional waves. Our data set consists of 86 405 long-period P and PP–P traveltimes measured by cross-correlation. The traveltime of a finite-frequency wave is sensitive to anomalies in a hollow banana-shaped region surrounding the unperturbed ray path, with the sensitivity being...

In Ref. [ 1 ] the propagation of a longitudinal slow mode parallel to an applied magnetic field has been observed in a magneto-rheological slurry. This mode has been discussed in terms of a Biot slow compressional wave as it is found in porous fluid-saturated media [ 1-3 ]. The slow mode described in ref. 1 is only observed in the presence of an external magnetic field. This feature all by itse...

Gas Hydrates are widely distributed in the near surface at high latitudes and many ocean bottoms. Our laboratory measurements help calibrate the seismic and well log data that are used to ascertain the in situ distribution of hydrates. Ultrasonic velocities are measured in unconsolidated sand specimen under thermobaric conditions comparable to those found in shallow oceanic or permafrost region...

INTRODUCTION Two of the persistent problems in finite-difference solutions of the elastic wave equation are the limited stability range of the free-surface boundary condition and the boundary condition's treatment of lateral variations in velocity and density. The centered-difference approximation presented by Alterman and Karal ( 1968), for example, remains stable only for 1:1/a greater than 0...