17 May 2005 Statistical detection method for time of arrival and frequency of waves
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One of the most promising NDT technologies is the guided ultrasonic wave technology. The most useful guided ultrasonic wave is Lamb waves. Damage detection and (or) nondestructive evaluation of structures using Lamb waves may be completed by the comparison between the analytic and the experimental dispersion diagram of Lamb waves. In order to construct the experimental dispersion diagram, the estimation of group velocities of each Lamb modes is necessary. Time of arrival information is needed to calculate the group velocity of each Lamb mode, and frequency information is needed to tell the Lamb modes from receiving signals because at least two modes are present at same frequency. Current research for detection of the time of arrival and the frequency is either in time domain or in frequency domain. However, these methods were not designed to give simultaneous information of the time and the frequency. Furthermore the scattering of waves and the background noise often mask the signal, leading difficulties in its estimation of the time of arrival and the frequency of the reflected and transmitted of dispersive Lamb waves. In this study, the authors introduce a detection method to estimate the time of arrival and the frequency simultaneously via time-frequency representation and to resolve the noise problem based on statistical signal detection theory. Numerical experiments were conducted to verify and validate the capability of the proposed method. The results of experiments demonstrate the utility of the proposed method.
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Sung Woo Shin, Sung Woo Shin, George M. Lloyd, George M. Lloyd, Ming L. Wang, Ming L. Wang, "Statistical detection method for time of arrival and frequency of waves", Proc. SPIE 5765, Smart Structures and Materials 2005: Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems, (17 May 2005); doi: 10.1117/12.593474; https://doi.org/10.1117/12.593474

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