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An important issue in ultrasonic nondestructive testing is the detection of flaw echoes in the presence of background noise created by instrumentation and by clutter noise. Signal averaging, autoregressive analysis, spectrum analysis, matched filtering, and the wavelet transform have all been used to filter noise in ultrasonic signals. Widely-used wavelet threshold estimation algorithms are not designed...
Electromagnetically induced acoustic emission (EMAE) technique is a new nondestructive testing (NDT). It does nondestructive detection with the effect of dynamic electromagnetic loading to generate a stress field stimulating stress waves from the defects. When EMAE is used to detect crack in the metal sheets, the EMAE signal is easy to be disturbed by various sources of noises, and the detectability...
A method of wavelet packet frequency decomposition was proposed, and it was used to analyze the vehicle interior noise signal and take feature extraction, the characteristic vector of total average statistical was constructed after feature extraction. Meanwhile the vector of sound quality calculated from the objective quantization mathematics model was also constructed. Then the correlation coefficient...
The wavelet packet plays an important role in the signal processing of electromagnetic acoustic emission. It can eliminate signals noise, and basing on it, improves the accuracy of acoustic emission source location. The wavelet packet algorithm is a further breakdown of orthogonal wavelet decomposition; it allows the observation of characteristics of signal transaction in a narrower band, so it increases...
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