caa a22 4500 475843169 CHVBK 20180406123906.0 cr unu---uuuuu 170329e20000301xx s 000 0 eng 10.1023/A:1006671706818 doi (NATIONALLICENCE)springer-10.1023/A:1006671706818 Frequency-Wavenumber Migration of Ultrasonic Data [Elektronische Daten] [Young-Fo Chang, Chir-Cherng Chern] In ultrasonic nondestructive evaluation (NDE), the depth of the image is usually calculated by multiplying the traveling time of the echoes with the velocity of the medium. If the flaw is not a horizontal plane, the flaw images may be distorted and mislocated. Although the lateral resolution and sizing accuracy of the flaw image can be improved using the digital signal processing methods, e.g., the utilization of the blocking filter or deconvolution filter, these methods do a little favor about the distortion and mislocation problems. The migration, an image-processing method used widely in reflection seismology, is introduced to process the ultrasonic data in this study. Since the signals are coherent and the noises are random, the flaw image can be transformed from its apparent position to the true position using the migration method and the resolution of the image may be improved. Not only the real positions of the oblique cracks can be found upon applying the frequency-wavenumber (F-K) migration to process ultrasonic data, but, in addition, the dimensions of the flaws can be estimated more accurately. Results presented in this study show that the migration method can be applied successfully to the ultrasonic data processing and can improve the quality of ultrasonic image in both size and location of the flaws. Plenum Publishing Corporation, 2000 ultrasonic NDE nationallicence reflection seismology nationallicence migration nationallicence Chang Young-Fo Institute of Applied Geophysics, Institute of Seismology, National Chung Cheng University, Ming-Hsiung, Chia-Yi, Taiwan aut Chern Chir-Cherng Geophysical Data Processing Center, Offshore and Overseas Petroleum Exploration Division, Chinese Petroleum Corporation, Taipei, Taiwan aut Journal of Nondestructive Evaluation Kluwer Academic Publishers-Plenum Publishers 19/1(2000-03-01), 1-10 0195-9298 19:1<1 2000 19 10921 https://doi.org/10.1023/A:1006671706818 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1006671706818 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Chang Young-Fo Institute of Applied Geophysics, Institute of Seismology, National Chung Cheng University, Ming-Hsiung, Chia-Yi, Taiwan aut NATIONALLICENCE 700 1- Chern Chir-Cherng Geophysical Data Processing Center, Offshore and Overseas Petroleum Exploration Division, Chinese Petroleum Corporation, Taipei, Taiwan aut NATIONALLICENCE 773 0- Journal of Nondestructive Evaluation Kluwer Academic Publishers-Plenum Publishers 19/1(2000-03-01), 1-10 0195-9298 19:1<1 2000 19 10921 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer