Analysis of the circumferential acoustic waves backscattered by a tube using the time-frequency representation of Wigner-Ville

Abstract

This paper presents a study of the group velocity dispersion of some circumferential waves propagating around an elastic tube. The dispersive character of the circumferential waves is theoretically known, but the experimental measurement of the group velocity in a dispersive medium is still a complex operation. We have determined the characteristics of the circumferential wave dispersion for aluminium and steel tubes using a time-frequency representation. Among these time-frequency techniques, the Wigner-Ville distribution (WVD) is used here for its interesting properties in terms of acoustic applications. The WVD is applied to the analysis of the dispersion of S0 symmetric and A1 antisymmetric circumferential waves propagating around a tube with a radii ratio equal to 0.95 (internal radius:external radius). This allowed us to determine their group velocities and reduced cutoff frequencies. The results obtained are in good agreement with the calculated values using the proper modes theory.

Acoustic analysis and Modeling of the Group and phase Velocities of an Acoustic circumferential waves by an Adaptative Neuro-Fuzzy Inference System (ANFIS)

“…Its robustness, speed and accuracy of its outputs enable it to give correct decisions and avoid cases of indecision. The use of the ANFIS does not present any approximation as in the case of the natural modes method which assimilates the tubes to the plates with the same thickness and that is not sullied with errors as in the case of the time-frequency representations of Wigner-Ville that determines the group velocity manually starting from the time-frequency image [9]. This article can be used as a new tool for characterization of an elastic tube.…”

Parametric and Non Parametric Time-Frequency Analysis of Biomedical Signals

“…The majority of the non parametric time-frequency representations are represented by the cohen class [7][8][9][10][11][12][13][14][15]. This class includes inter alias the Wigner-Ville distributions.…”

“…In this study, the two major categories of the time-frequency techniques are utilized, the parametric and the non-parametric ones. The chosen time-frequency techniques are selected for their interesting proprieties [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. The used time-frequency techniques are: Periodogram, Capon, Choi-williams and Smoothed pseudo Wigner-Ville.…”

Modeling the Cut-off Frequency of Acoustic Signal with an Adaptative Neuro-Fuzzy Inference System (ANFIS)

“…In the case of a thin plaque, the cut-off frequencies of the symmetric and anti-symmetric Lamb waves are given by [2,14]: The cut-off frequencies, of the symmetric and antisymmetric circumferential waves, are determined by exploiting the equations 3, 7 and 8 [2,14]:…”

“…Such parameters may be found from the velocity dispersion of the circumferential waves (S i and A i ), since it is directly related to the geometry and to the physical properties of the shell. Different methods have been proposing for analyse of the circumferential waves propagating around the cylindrical shell which includes temporal analysis [7,9], spectrum analysis [5,7], parametric time-frequency analysis [10][11][12][13][14][15][16], wavelet transform [19][20] and neural networks [21][22].…”