Wave scaterring by a periodic array of in-plane cracks at the interface between dissimilar media

We investigate analytically the behaviour of time-harmonic elastic waves in the neighbourhood of a plane interface between dissimilar elastic media, where a periodic array of in-plane cracks exists. Waves incident on such a boundary excite a lot of propagating and evanescent scattered waves, and the incident energy is subjected to a complicated process of redistribution. The aim of the work is to quantify the amount of incident wave energy partitioned among the propagating scattered waves. The scattered fields are expressed in terms of Fourier series with coefficients depending on Legendre functions. Energies associated with the scattered waves are evaluated as a function of the incidence angle, and results are presented for three different distributions of the cracks at the interface. We show that the amount of the reflected wave energy and the amount of the diffracted wave energy increase with increasing percentage of cracks at the interface. We also suggest that, contrary to the case of an interface between identical media, the energy conservation law cannot be applied in the work presented here since phenomena associated with interface wave scattering are not taken into account

Structure analysis and denoising using Singular Spectrum Analysis: Application to acoustic emission signals from nuclear safety experiments

International audienceWe explore the abilities of the Singular Spectrum Analysis (SSA) to characterize and denoise discreteacoustic emission signals. The method is first tested on simulated data for which different types andlevels of noise are considered. It is then applied on real data recorded from nuclear safety experiments.The results show an excellent ability of the SSA to characterize the corrupted signal and to detect structuralchanges, even for low signal-to-noise ratio. For denoising purposes, the quality of the resultsdepends mainly on the separability between the source signal to be estimated and the noise. However,whatever the case, the main components of the source signal are clearly identified when the componentsassociated with the noise are removed

Which Methods and Strategies to Cope with Noise Complexity for an Effective Interpretation of Acoustic Emission Signals in Noisy Nuclear Environment?

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