MATCHING PURSUIT-BASED ANAPTIVE WAVELET PACKET ATOMIC DECOMPOSITION APPLIED IN ULTRASONIC INSPECTION

摘要

A novel method of time-frequency amalysis, wavelet packet atomic decomposition based on Matching Pursuit (MP) algorithm, is proposed to improve ultrasonic flaw detection in ultrasonic NDT. MP algorithm is used to decompose the nonlinear and non-stationary signal into given atoms in an over-complete wavelet packet dictionary. The wavelet packet dictionary with Daubechies wavelet function is selected, which well match the observed ultrasonic flaw echoes. Selecting adaptively the optimum atoms to reconstruct signal can obtain spares approximations of the original signal with the less complexity and efficiently improve signal corrupted by noise. Computer simulation and experimental results have verified distinct SNR enhancement for ultrasonic echo in flaw detection.