given the sensitivity of current ground-based gravitational wave (gw) detectors, any continuous-wave signal we can realistically expect will be at a level or below the background noise. hence, any data analysis of detector data will need to rely on statistical techniques to separate the signal from the noise. while with the current sensitivity of our detectors we do not expect to detect any tru...

In spite of wide spread investigations performed,the biological effects of ultrasound waves,specially on DNA molecule has not been fully understood.since any alteration in DNA molecule can lead to chromosome abnormality,the study of clastogenic effects of ultrasound is important.in this study,the effect of 1MHz frequency continuous waves with the power of 0.5,1 and 1.5 watts on G human lymphocy...

There are three general methods that can be used to determine formation velocities from full waveform logs. The first approach is to make use of the data from the entire waveform. This type of velocity analysis is performed either in the frequency domain (I.e. f-k analysis or the two station method) or in the time domain (I.e. velocity spectral analysis). The second approach is to identify the ...

A sparse array guided wave tomography system is investigated for monitoring plate wall thinning status caused by corrosion/erosion. Because of their group velocity dependence on the structure wall thickness of some special modes, ultrasonic guided waves are sensitive to structure wall thinning status. As a low resolution imaging technique, a sparse array system provides many advantages. First, ...

Lamb waves are often used in ultrasonic applications for non-destructive testing of large constructions. The difficulty in the analysis of Lamb waves is their dispersive characteristics, especially their frequency dependent phase and group velocities. This article focuses on the separation of the first symmetric mode S0 and the first asymmetric mode A0 and the reliable estimation of their group...

stress waves contain useful information about the properties of porous materials; they can be recovered through different non-destructive testing methods such as crosswell, vertical seismic profile, borehole logging as well as sonic tests. in all these methods, it is crucial to assess the effects of frequency on wave attributes including velocity and intrinsic attenuation. the dependency of per...

Wave scattering analysis implemented by boundary element methods (BEM) and the normal mode expansion technique is used to study the sizing potential of two-dimensional shaped defects in a wave guide. Surface breaking halfelliptical shaped defects of three opening lengths (0.3, 6.35 and 12.7 mm) and through-wall depths of 10–90% on a 10 mm thick steel plate were considered. The reflection and tr...

This paper presents a set of analytical and numerical results on the use of guided waves for structural health monitoring application. The aim of the work presented in this paper is to provide tools to extend modeling capacities and improve quality and reliability of guided wave propagation models using commercially available finite element (FE) packages. Predictive simulation of ultrasonic non...