We discuss the use of a genetic algorithm (GA) to invert data for many acceptable solutions, in contrast to inversion for a single, "optimum" solution. The GA is a directed search method which does not need linearization of the forward problem or a starting model, and it can be applied with a very large mode!-space. Consequently, fewer assumptions are required and a greater ange of solutions is...

We have performed atomic simulations of crack propagation along a weak interface joining two harmonic crystals. The simulations show that a mode II shear dominated crack can accelerate to the Rayleigh wave speed and then nucleate an intersonic daughter that travels at the longitudinal wave speed. This contradicts the general belief that a crack can travel no faster than the Rayleigh speed.

The longitudinal, transverse and torsional wave dispersion curves in single walled carbon nanotubes (SWCNT) are used to estimate the non-local kernel for use in continuum elasticity models of nanotubes. The dispersion data for an armchair (10,10) SWCNT was obtained using lattice dynamics of SWNTs while accounting for the helical symmetry of the tubes. In our approach, the Fourier transformed ke...

An original method is presented to determine the complex Lamb wave spectrum by using a numerical spectral method applied to the elasticity equations. This method presents the advantage to directly determine complex wave numbers for a given frequency via a classical matricial eigenvalue problem, and allows the wave numbers to be determined at relatively high frequencies (i.e., corresponding to m...

data transmission in optical systems and increased transmission distance capacity benefit by using optical amplification wavelength division multiplexing (wdm) technology. the combination of four waves (fwm) is a non-linear effect in the wavelength division multiplex (wdm), when more than two wavelengths of light in a fiber launch will occur. fwm amount depends on the channel, the channel spaci...

We investigated upper crustal structure with data from a dense seismic array deployed around Mount St. Helens for 2 weeks in the summer of 2014. Interstation cross correlations of ambient seismic noise data from the array were obtained, and clear fundamental mode Rayleigh waves were observed between 2.5 and 5 s periods. In addition, higher-mode signals were observed around 2 s period. Frequency...

Abstract—Stoneley waves are interface waves that propagate at the interface between two solid media. In this study, the dispersion characteristics and wave structures of Stoneley waves in elastic multilayered plates are displayed and investigated. With a perspective of bulk wave, a reasonable assumption of the potential function forms of the expansion wave and shear wave in nth layer medium is ...

Ultrasonic guided wave inspection is much more efficient than traditional point-bypoint examination. Guided waves can propagate over long distances from a single position, and therefore is a good method of evaluating thickness degradation, especially for large-area structures such as pipes and vessels. In this paper, guided wave thickness measurement potential is studied utilizing a peak freque...