Arrival-time structure of the time-averaged ambient noise cross-correlation function in an oceanic waveguide

2005 ◽  
Vol 117 (1) ◽  
pp. 164-174 ◽  
Author(s):  
Karim G. Sabra ◽  
Philippe Roux ◽  
W. A. Kuperman
Keyword(s):  
Correlation Function ◽  
Ambient Noise ◽  
Cross Correlation ◽  
Arrival Time ◽  
Time Structure ◽  
Cross Correlation Function ◽  
Oceanic Waveguide ◽  
Noise Cross Correlation

Crack Size Estimation Using a Combination of Cross Correlation and Phase Shift Correction in Ultrasonic Time-of-Flight Diffraction Method

2009 ◽  
Vol 413-414 ◽  
pp. 305-312
Author(s):  
Yong Hong Zhang ◽  
Ming J. Zuo ◽  
Xiao Dong Wang
Keyword(s):  
Correlation Function ◽  
Phase Shift ◽  
Cross Correlation ◽  
Arrival Time ◽  
Time Of Flight ◽  
Crack Size ◽  
Cross Correlation Function ◽  
Maximum Peak ◽  
Time Of Flight Diffraction ◽  
Ultrasonic Time

The ultrasonic time-of-flight-diffraction (TOFD) detection method has been widely used in crack size assessment. The key issue in TOFD is to determine the arrival time of crack tip diffracted signal. In the traditional cross correlation method, the resulting maximum peak of cross correlation function between two signals indicates the time of flight between them. In practical ultrasonic measurement, the transmission wave may be distorted and phase shift may be introduced. This paper presents a method using cross correlation and phase shift correction to improve the accuracy of crack sizing in the TOFD framework. The resulting maximum peak of the cross correlation function between two signals combining with time delay introduced by phase shift determine the arrival time of diffracted signal. Experimental results are used to demonstrate the advantage of the proposed method.

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