An adaptive endpoint detection algorithm based on band energy and adaptive smoothing algorithm is described. This algorithm utilizes the capability of adaptive smoothing algorithm that intensifies the discontinuity be...An adaptive endpoint detection algorithm based on band energy and adaptive smoothing algorithm is described. This algorithm utilizes the capability of adaptive smoothing algorithm that intensifies the discontinuity between local areas. The band energy features are selected because of their usefulness in detecting high energy regions (in the incoming signal) and making the distinction between speech and noise. Heuristic 'edge-focusing' is used to endpoint detection to save the time in iteration.展开更多
The ultrasonic testing for the defects of complete disbond in multi-layered structure with lower acoustic impedance beneath a high acoustic impedance overburden is one of the difficult problems in ultrasonic nondestru...The ultrasonic testing for the defects of complete disbond in multi-layered structure with lower acoustic impedance beneath a high acoustic impedance overburden is one of the difficult problems in ultrasonic nondestructive testing field. A model of a multi-layered steel-rubber composite plate is depicted. Because the acoustic impedance of the steel differs far from that of the couplant water and the rubber, the energy of the signal reflected from the debonded rubber layers is very weak. More over, the flaw echoes are masked by the strong echoes reverberated in the steel plate. It's nearly impossible to identify the debonding echoes directly. The subband adaptive filtering method is discussed in the paper, where the subband decomposition is performed by mutual wavelet packets decomposition on the criterion of maximizing the cross-correlation between the signals. The simulations on both synthetic and real signals are presented. The echoes from the delaminated flaw at the depth of 5 mm in the rubber from the calculated signal, and echoes from the flaw at the depth of 3 mm from the real signal are extracted successfully.展开更多
文摘An adaptive endpoint detection algorithm based on band energy and adaptive smoothing algorithm is described. This algorithm utilizes the capability of adaptive smoothing algorithm that intensifies the discontinuity between local areas. The band energy features are selected because of their usefulness in detecting high energy regions (in the incoming signal) and making the distinction between speech and noise. Heuristic 'edge-focusing' is used to endpoint detection to save the time in iteration.
基金This work was supported by the National Science Foundation of China (No. 19974063) and the President Foundation of the Institute of Acoustics, Chinese Academy of Sciences.
文摘The ultrasonic testing for the defects of complete disbond in multi-layered structure with lower acoustic impedance beneath a high acoustic impedance overburden is one of the difficult problems in ultrasonic nondestructive testing field. A model of a multi-layered steel-rubber composite plate is depicted. Because the acoustic impedance of the steel differs far from that of the couplant water and the rubber, the energy of the signal reflected from the debonded rubber layers is very weak. More over, the flaw echoes are masked by the strong echoes reverberated in the steel plate. It's nearly impossible to identify the debonding echoes directly. The subband adaptive filtering method is discussed in the paper, where the subband decomposition is performed by mutual wavelet packets decomposition on the criterion of maximizing the cross-correlation between the signals. The simulations on both synthetic and real signals are presented. The echoes from the delaminated flaw at the depth of 5 mm in the rubber from the calculated signal, and echoes from the flaw at the depth of 3 mm from the real signal are extracted successfully.
