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CHARACTERIZING ultrasonic echo BY CWT AND ITS APPLICATION TO NONDESTRUCTIVE EVALUATION OF MATERIAL DAMAGES

CHARACTERIZING ULTRASONIC ECHO BY CWT AND ITS APPLICATION TO...

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2006 8th International Conference on Signal Processing

作者： MA Shiwei CHEN Guanghua LI Min LIU Zhongjie LIANG Weibin School of Metratronic ＆ Automation Shanghai Kay Lab of Power Station AutomationShanghai University

ISBN: (纸本)0780397371;9780780397378

＜正＞ultrasonic echoes,which contain useful information related to material micro-damages in nondestructive evaluation, usually exhibit involved time-varying frequency *** this paper,Continuous wavelet transform（CWT） based time-frequency analysis for echo signal were discussed. ultrasonic testing of pulse-echo technique with high frequency contact transducers was carried out to thermally degraded Cr-Mo steel samples processed by different high temperature heat treatment *** echo signals were analyzed by CWT based on Gabor *** major frequency dependent ultrasonic parameters,attenuation and velocity,were obtained from the local peak values at each frequency from the magnitude of ***,numerical correlations of the attenuation coefficients and group velocity with the sample’s internal grain size were *** method has a potential for quantitative evaluation to damage advance before crack initiation.

关键词： continuous wavelet transform time-frequency analysis ultrasonic echo nondestructive evaluation

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ultrasonic echo Tracking Based on Improved Newton Iteration

Ultrasonic Echo Tracking Based on Improved Newton Iteration

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第37届中国控制会议

作者： ZHANG Hongmei CHEN Mingjie SUN Xiwei FENG Naizhang College of Automation Harbin Engineering University

In clinical medicine, the elasticity of artery reflects diastolic function, and it is one of the important indicators of diagnosis of cardiovascular disease. ultrasonic echo tracking is a kind of new technology risen in recent years to detect arterial elasticity. Arterial elasticity coefficients are got by processing the ultrasound echo signal transmitted in different organs and tissue of human. In ultrasonic echo tracking, accurately estimate the time shift between two signals or phase shift is the key problem of elasticity estimation. Although the correlated technique can be used to realize, yet its calculation problem is the bottleneck of the implementation. In this paper, an improved Newton iterative algorithm was applied to estimate time shift of ultrasonic echo signal, so the precise time displacement estimation was achieved, and the problem of aliasing was overcome at the same time. In addition, because the ultrasonic echo data is large, and large part of it is unnecessary, so an adaptive testing blood vessel position tracking gate setting technology is proposed to improve the efficiency of data processing, and it reduced the computational complexity to a certain extent and improve the efficiency of data processing.

关键词： ultrasonic echo echo tracking vascular elasticity detection Newton iteration method zero crossing

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