An unconsolidated, saturated marine sediment consists of a more or less loose assemblage of mineral grains in contact, with seawater in the interstices. It is postulated that the two-phase medium possesses no skeletal frame, implying that the elastic rigidity modulus of the material is zero. A theory of wave propagation in such a sediment is developed, in which the medium is treated as a fluid ...

The theory of the acoustics of patchy-saturation in porous media is used to analyze experimental data on wave velocity and attenuation in partially water saturated limestones. It is demonstrated that the theory can be used to deduce the value of V /A, the ratio of the volume to area of the water patch, and l f , the Poisson size of the water patch. One can " hear " the shape of a patch if the p...

development of ultrasound technique has not been progressing for evaluating the internal quality of fruits as fast as that of processed foods. in this research for quality assessment of pear fruit (shah miveh variety) an ultrasonic measurement system was constructed to transmit and receive the ultrasonic waves. the apparatus included a pulser-receiver, a pair of 75 khz ultrasonic transducers wi...

Creager and Jordan [1986] propose that penetration of subducting slabs under the Kurile Islands and other subduction zones to depths of at least 1000 km is necessary to explain travel time anomalies of deep earthquakes. Such penetration would also be expected to affect the amplitudes and waveforms of the body waves from earthquakes. Synthetic seismograms appropriate for a record section in a pl...

The Kelvin–Helmholtz (KH) instability of magnetohydrodynamic surface waves at the low latitude boundary layer is examined using both an eigenfrequency analysis and a time-dependent wave simulation. includes effects sheared flow Alfvén velocity gradient. When magnetosheath flows are perpendicular to ambient magnetic field direction, unstable KH that propagate obliquely direction occur when Mach ...

[1] Using traveltimes of teleseismic body waves recorded by several temporary local seismic arrays, we carried out finite‐frequency tomographic inversions to image the three‐ dimensional velocity structure beneath southern Tibet to examine the roles of the upper mantle in the formation of the Tibetan Plateau. The results reveal a region of relatively highP and S wave velocity anomalies extendin...

S–P travel-time residuals and receiver-function images are used to infer the Vp/Vs (compressional to shear wave velocity) ratio of the lithospheric mantle beneath southern African and the topography of the underlying 410-km discontinuity. Low Vp/Vs ratios provide evidence independent of geochemical observations for a highly depleted root (Mg#f92–94) beneath the Kaapvaal craton. The receiver-fun...

We consider the ray limit of propagating ultrasound waves in three-dimensional bodies made from a homogeneous, isotropic, elastic material. Using a Monte Carlo approach, we simulate the propagation and proliferation of elastic rays using realistic angle-dependent reflection coefficients, taking into account mode conversion and ray splitting. For a few simple geometries, we analyze the long-time...