We have studied the formation of relativistic solitary waves due to nonlinearinteraction of strong electromagnetic wave with the plasma wave. Here, our plasma isrelativistic both in temperature and in streaming speed. A set of equations consisting ofscalar and vector potentials together with a third order equation for the enthalpy inphoton gas plasma is obtained analytic...

The ability of the grain shearing (GS) and viscous grain shearing (VGS) models to relate geophysical and acoustic properties is tested by a method based on the claimed tight coupling between compressional and shear wave speeds and attenuations, which allows the test result to be quantified in a single parameter. The VGS model is claimed to provide a better fit to the measured sound speed and at...

This study has been motivated by the observed difference in the range of the power-law attenuation exponent for compressional and shear waves. Usually compressional attenuation increases with frequency to a power between 1 and 2, while shear wave attenuation often is described with powers less than 1. Another motivation is the apparent lack of partial differential equations with desirable prope...

A pseudospectral model of linear elastic wave propagation is described based on the first order stress-velocity equations of elastodynamics. k-space adjustments to the spectral gradient calculations are derived from the dyadic Green's function solution to the second-order elastic wave equation and used to (a) ensure the solution is exact for homogeneous wave propagation for timesteps of arbitra...

Wave propagation in a stratified fluid / porous medium is studied here using analytical and numerical methods. The semi-analytical method is based on an exact stiffness matrix method coupled with a matrix conditioning procedure, preventing the occurrence of poorly conditioned numerical systems. Special attention is paid to calculating the Fourier integrals. The numerical method is based on a hi...

Recently developed airborne ultrasonic inspection techniques can supplement other methods routinely used for materials characterization of permeable solids. In particular, the velocity and attenuation of the slow compressional wave transmitted through thin plates of a few millimeter thickness can be used to assess the tortuosity and dynamic permeability of the specimen. The main advantage of th...

A novel method for the excitation of ELF waves in the ionosphere is presented. It utilizes the nonlinear mixing of two groundor satellite-produced radio frequency waves with a compressional Alfv6n wave. Parametric amplification thresholds are estimated to be between 10 and 20 MW peak power for 5-MHz pumps producing waves in the ELF range. Potential applications to ELF communications are discussed.

In recent years, a theory of wave propagation in marine sediments has been developed, based on the grain-to-grain interactions that occur during the passage of compressional and shear waves. The theory yields a dispersion pair, representing phase speed and attenuation, for each wave. These expressions are functions of frequency and the physical properties of the sediment, that is, the porosity,...

Laboratory and in situ velocity measurements have been made on six piston cores taken in the western North Atlantic Ocean. Sediments from the southwestern Bermuda Rise and Greater Antilles Outer Ridge are clays having velocities ranging mostly from 1500 to 1530 m/s and velocity gradients near 1 s -•. In cores from the Nares Abyssal Plain, the clayey sediments have comparable velocities, but int...

The Intensity Vector Autonomous Recorder (IVAR) measures acoustic particle velocity and pressure simultaneously. IVAR was deployed on the seabed during 2017 Seabed Characterization Experiment (SBCEX) with primary objective to study sound propagation within underwater waveguides for which consists of fine-grained, muddy sediments. In this study, a Bayesian framework is applied noise recorded by ...