Evaluation of the dispersive phase and group velocities using harmonic wavelet transform

The evaluation of the dispersive phase and group velocities having sensible physical meaning is of practical importance in various NDT techniques. In this paper, we propose a method based on the harmonic wavelet transform to evaluate dispersive phase and group velocities. To apply the harmonic wavelet transform in the evaluation of dispersive velocity, the meaning of the harmonic wavelet coefficient is interpreted from a different point of view. Based on these concepts, the step-by-step procedure to evaluate the dispersive phase and group velocities was proposed. In the proposed method, both phase and group velocities can be obtained directly from information extracted from data based on the harmonic wavelet transform. To evaluate the validity of the proposed method, numerical simulations of the multi-layered system were performed and the phase and group velocities determined by the proposed method match very well with theoretical velocities showing the good potential of the proposed method. (C) 2001 Elsevier Science Ltd. All rights reserved.