Target classification is one of the most important issues in battlefield situational awareness. As seismic signals are an effective means of obtaining such information, any knowledge of the subsurface environment in which the target signal propagates is very important in either developing or fine-tuning classification algorithms. Seismic signal attenuation is an essential subsurface environment...

A relaxation process, with the associated phenomenology of sound attenuation and sound velocity dispersion, is found in a simulated harmonic Lennard-Jones glass. We propose to identify this process with the so-called microscopic (or, instantaneous) relaxation process observed in real glasses and supercooled liquids. A model based on the memory function approach accounts for the observation and ...

OBJECTIVES The effectiveness of hearing protection devices (HPDs), when used in workplace conditions, has been shown over the years to be usually lower than the labeled values obtained under well-controlled laboratory conditions. Causes for such discrepancies have been listed and discussed by many authors. This study is an attempt to understand the issues in greater details and quantify some of...

Two concepts of plane waves in anisotropic viscoelastic media are studied. One of these concepts allows for the use of methods based on the theory of complete Bernstein functions. This allows for a deeper study of frequency-domain asymptotics of the attenuation function and timedomain regularity at the wavefronts. A relation between the direction of the energy flux density and the attenuation v...

The measurement of the acoustic properties of highly attenuative materials such as bitumen is very difficult. One possibility is to use measurements of the extent to which filling a cylindrical waveguide with the material affects the dispersion relationship of the cylinder. Torsional modes have been excited using piezoelectric transducers placed at one end of the cylinder, while the phase veloc...

In the present paper, a gyrotron cavity is analyzed in the absence of electron beam for dispersion, attenuation and RF efficiency. For all these characteristics, azimuthally symmetric TE0n modes have been considered. The attenuation characteristics for TE0n modes indicated decrease in attenuation constant as the frequency is increased. Interestingly, the lowest order TE01 mode resulted in lowes...

Estimating the characteristic correlation length of tissue microstructure from the backscattered power spectrum could improve the diagnostic capability of medical ultrasound. Previously, size estimates were obtained after compensating for source focusing, the frequency-dependent attenuation along the propagation path (total attenuation), and the frequency-dependent attenuation in the scattering...

This article describes a mechanical vertical attenuation system capable to provide large attenuation factors above 1Hz. This system is derived from, and improves, the passive Geometric Anti-Spring seismic attenuation filters minimizing their vertical resonant frequency by means of a tunable electromagnetic spring mounted in parallel with the main spring. The tunable spring is also used to compe...

Photothermal techniques are based on the thermal waves detection, such waves are generated when a modulated light strikes on a sample material, thermal waves then travel through the material, is the material is homogenous then thermal waves propagate freely and, only suffering an attenuation as a function of traveled distance, when the material has defects the waves will suffer not only attenua...

Photothermal techniques are based on the thermal waves detection, such waves are generated when a modulated light strikes on a sample material, thermal waves then travel through the material, is the material is homogenous then thermal waves propagate freely and, only suffering an attenuation as a function of traveled distance, when the material has defects the waves will suffer not only attenua...