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A new approach is used to predict the acoustic form function (FF) for an infinite length cylindrical shell excited perpendicularly to its axis using the artificial neural network (ANN) techniques. The Wigner-Ville distribution is used like a comparison tool between the FF calculated by the analytical method and that predicted by the ANN techniques for a stainless steel tube. During the development of the network, several configurations are evaluated for various radius ratios ba (a: outer radius: b: inner radius of the tube). The optimal model is a network with one hidden layer. It is able to predict the FF with a mean relative error about 1.61% for the cases studied in this paper.

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Two artificial neural networks (ANN) models are developed to predict the evolution of group velocity and peak to peak amplitude of an ultrasonic wave propagate in mortar, also we these models use it to know the acoustic impedance during hydration of mortar specimen. The useful data bases to train and to test the performances of the models are collected from the experiences done on the mortar dough. In this study, the temperature, the mass reports of cement on sand, water on cement and the time of the manipulation, are retained like relevant entries of our models. Several network configurations are evaluated. For the two architectures of models, the optimal model selected is an ANN with only one hidden layer. These models are able to predict respectively group velocity, acoustic impedance and peak to peak amplitude evolution with the means relative errors (MRE) of 0.29% and 0.35% and 4%.

The normal excitation of a tube immersed in water by the acoustic plane wave, circumferential waves are generated inside the shell. These circumferential waves, standing form stationary waves on the circumference of the tube for some frequencies. These stationary waves, constituting resonances of the tube which are perfectly visible on the backscattered spectrum. Moreover, the studies carried out on the diffusion of a plane acoustic wave by target were based primarily on the use of the monodimensional methods (Temporal domain and/or frequencial domain). To exceed the disadvantages of these methods, in this work, we used the time-frequency representations such as the Short-Term Fourier Transform (STFT), Wigner-Ville Distribution (WVD) and Wavelet Transform method. These representations are applied to a theoretical signal backscattered by a tube of aluminium, copper and steel with radii ratio b/a = 0.95 (a is the external radius, and b the internal radius). From the time-frequency images obtained we have visualized the dispersion of circumferential waves (S0, A1, S1,œ) and identified these different waves. This analysis permits to compare between these time-frequency representations. And also we have compared between the cut-off frequencies of circumferential waves obtained from these representations and those computed by the proper modes theory of the vibration.