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To realize automatic flaw classification of an ultrasonic phased array system, the key is to extract flaw feature that can mostly represent flaw's nature from ultrasonic signals. As ultrasonic echoes are nonstationary signals, wavelet packet transform (WPT) is a common feature extraction method. But it is fit for off-line signal analysis. In this article, lifted wavelet transform (LWT) is studied...
Presently, flaw classification of ultrasonic phased array systems is completely manual. It is dependent on the operator's testing experiences and errors are very easily introduced. In this article, "energy-status" method based on wavelet packet transform, having time-frequency signal analysis character, is applied to achieve ultrasonic echo signals' feature. Then, a feature library is built...
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