Journal ArticleDOI
Frequency-Wavenumber Migration of Ultrasonic Data
Young-Fo Chang,Chir-Cherng Chern +1 more
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TLDR
In this article, the frequency-wavenumber (F-K) migration was applied to the ultrasonic data processing and can improve the quality of ultrasonic image in both size and location of the flaws.Abstract:
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.read more
Citations
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Journal ArticleDOI
Stolt's f-k migration for plane wave ultrasound imaging
TL;DR: This work showed that the ERM can be made suitable for PWI by a spatial transformation of the hyperbolic traces present in the RF data, and showed that multi-angle compounded f-k migrated images are of quality similar to those obtained with a state of the art dynamic focusing mode.
Journal ArticleDOI
The wavenumber algorithm for full-matrix imaging using an ultrasonic array
TL;DR: A Fourier-domain approach to full-matrix imaging based on the wavenumber algorithm used in synthetic aperture radar and sonar, which has an improved point-spread function and provides better imagery and is several orders of magnitude faster than the TFM.
Journal ArticleDOI
Inverse wave field extrapolation: a different NDI approach to imaging defects
TL;DR: In this paper, imaging theory developed for seismic exploration of oil and gas fields on the NDI application is applied and synthetic data obtained from finite difference simulations is used to illustrate the principle of imaging.
Journal ArticleDOI
Synthetic aperture focusing of ultrasonic data from multilayered media using an omega-K algorithm
TL;DR: A similar focusing algorithm is presented called multi-layer omega-k (MULOK), which combines PSM and the ω-k algorithm to perform multilayer imaging more efficiently and shows that there is essentially no difference in image quality between the two algorithms.
Journal ArticleDOI
Arbitrarily wide-angle wave equations for complex media
TL;DR: In this article, a systematic procedure is developed for deriving a series of highly accurate space-domain versions of OWWEs for complex media where the governing equation (full wave equation) is a second order differential system.
References
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Book
Introduction to Geophysical Prospecting
TL;DR: In this paper, the basic principles of geophysical prospecting with emphasis on geological considerations and on geophysical instruments and methodology for the recording and processing of field data are reviewed, as well as advances in computer technology, field techniques and the analysis and interpretation of data.
Book
Ultrasonic methods of non-destructive testing
Jack Blitz,Geoff Simpson +1 more
TL;DR: In this article, the propagation of low amplitude ultrasound is discussed and the principles of ultrasonic testing are discussed. But the authors focus on the application of low-amplitude ultrasound to the testing of metals.
Journal ArticleDOI
Migration of seismic data
J. Gazdag,P. Sguazzero +1 more
TL;DR: A detailed overview of the major advances in this field can be found in this paper. But the main advances in the field are in three major categories: integral solutions, depth extrapolation, and time extrapolation.