Location

La Jolla ,CA

Start Date

1-1-1989 12:00 AM

Description

Electromagnetic methods of nondestructive testing find widespread application in industry. A vast majority of the defect characterization schemes using electromagnetic methods involve estimation of the size and/or shape of the defect on the basis of a one dimensional signal obtained by scanning the surface of the test specimen using a suitable transducer [1–3]. Recent years have witnessed increasing interest in the development of imaging techniques for characterizing defects. As an example, eddy current imaging methods involve a raster scan of the surface of the test specimen to obtain a two dimensional image whose elements represent the real or imaginary components or alternatively the magnitude or phase of the impedance of the eddy current probe [4,5]. In the case of magnetostatic imaging methods, the specimen under test is scanned by a flux sensitive transducer such as a Hall probe. The image is obtained, typically, by treating the value of either the normal or tangential component of the flux density at each sample point as a gray level [6]. Inverse techniques proposed to date rely largely on phenomenological models for analyzing the images to obtain estimates of the size and shape of the defect [7–10]. Unfortunately, these techniques call for considerable computing resources.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

8A

Chapter

Chapter 3: Interpretive Signal and Image Processing

Section

Image and Signal Processing

Pages

769-776

DOI

10.1007/978-1-4613-0817-1_96

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

New Signal Processing Scheme for the Analysis of Electromagnetic Images

La Jolla ,CA

Electromagnetic methods of nondestructive testing find widespread application in industry. A vast majority of the defect characterization schemes using electromagnetic methods involve estimation of the size and/or shape of the defect on the basis of a one dimensional signal obtained by scanning the surface of the test specimen using a suitable transducer [1–3]. Recent years have witnessed increasing interest in the development of imaging techniques for characterizing defects. As an example, eddy current imaging methods involve a raster scan of the surface of the test specimen to obtain a two dimensional image whose elements represent the real or imaginary components or alternatively the magnitude or phase of the impedance of the eddy current probe [4,5]. In the case of magnetostatic imaging methods, the specimen under test is scanned by a flux sensitive transducer such as a Hall probe. The image is obtained, typically, by treating the value of either the normal or tangential component of the flux density at each sample point as a gray level [6]. Inverse techniques proposed to date rely largely on phenomenological models for analyzing the images to obtain estimates of the size and shape of the defect [7–10]. Unfortunately, these techniques call for considerable computing resources.