S U M M A R Y Seismic tomography has been one of the primary tools to image the interior of the earth and other elastic structures. To date the inversions of compressional (P) and shear (S) wave speeds have been carried out separately under the assumption that P traveltimes are affected only by the P wave speed of the elastic media and S traveltimes by the S wave speed. Using numerical and anal...

We hypothesized that age-linked changes in the composition and elastic properties of the arterial wall occur earlier in hypertensive than in normotensive rats. We evaluated the consequences of hypertension and aging on aortic mechanics, geometry, and composition in 3-, 9-, and 15-month-old awake Wistar-Kyoto rats (WKY) (normotensive) and spontaneously hypertensive rats (SHR) (hypertensive). The...

Methods of measuring ultrasonic wave velocity in an elastic sample require data on the thickness of the sample and/or the distances between the transducers and the sample. The uncertainty of the ultrasonic wave velocity measurements generally depends on that of the data available. Conversely, to determine the thickness of a material, it is necessary to have a priori information about the wave v...

It is shown, for the first time, that the transmittivity of wave guides created as rectilinear defects in periodic elastic band-gap materials oscillates as a function of frequency. The results are obtained using the finite difference time domain method for elastic waves propagating in two-dimensional inhomogeneous media. The oscillations of the transmittivity are due to the richness of modes in...

The velocity of elastic wave is usually the essential property that has to be measured in advance, when applying the civil NDT technique based on the theory of transient elastic wave. The accuracy and handiness of the velocity measuring method are often become a key about the practicability of the NDT method. In this paper, based on the transient elastic wave theory, an elastic-wave-velocity me...

In this paper, a problem on Rayleigh surface wave in an isotropic micropolar elastic solid half-space with impedance boundary conditions is investigated. It is assumed that the normal force traction, shear force traction and shear couple traction vary linearly with the normal displacement component, tangential displacement component and microrotation component multiplied by the frequency, where...

This paper gives two versions of elastic screen method The wide angle version has a better accuracy while the small angle approximation is more e cient The accu racy of the re ectivity is discussed by comparing the analytical results from the screen method and those directly from plane wave re ections The accuracy of waveform is checked by comparing synthetic seis mograms from both screen metho...

The propagation of surface waves in a fluid- saturated porous isotropic layer over a semi-infinite homogeneous elastic medium with an irregularity for free and rigid interfaces have been studied. The rectangular irregularity has been taken in the half-space. The dispersion equation for Love waves is derived by simple mathematical techniques followed by Fourier transformations.  It can be seen t...

This paper introduces a method to selectively reduce large time-reversed focal events to provide the potential to illuminate smaller events which have been masked by the larger one. The method is demonstrated for two elastic wave pulses emitted simultaneously from two spatially separated sources. The method improves upon the spatial resolution abilities of time reversed acoustics in nondestruct...

We have studied the velocity dispersion of guided waves in transversely isotropic formations. Theoretical velocity dispersion curves were calculated with elastic constants based on laboratory and field measurements and compared to dispersion curves for isotropic formations having the same vertical po and S-wave velocities. The symmetry axis for the transverse isotropy was parallel to the boreho...