Data acquisition for experimental verification of an eddy current model for three dimensional inversion

Nyenhuis, J.A.; Treece, Jeff C.; Drynan, John M.; Sabbagh, Harold A.; Sabbagh, L. David

doi:10.1109/tmag.1987.1065508

Cited by 10 publications

(4 citation statements)

References 4 publications

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“…As for the initial search directions they are chosen as the opposite of the gradients, i.e. along g (1) q and h (1) for MGM and along h (1) for STIE and LNA. Note that, since it depends upon the cost functional to be minimized, h (n) has a different expression for each of the three algorithms (cf the appendix).…”

Section: Initialization and Cooling Schemesmentioning

confidence: 99%

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Three-dimensional inversion of eddy current data for non-destructive evaluation of steam generator tubes

1998

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Three-dimensional (3D) eddy current non-destructive evaluation of steam generator tubes is cast in a wavefield integral framework and considered from an inverse problem point of view. Three inversion algorithms based on a gradient-type iterative search are studied: the modified gradient method, an inversion via the source-type integral equation, and one based on the localized nonlinear approximation. To overcome the inherent ill-posed nature of the inversion problem, a binary constraint is enforced on the contrast to be retrieved. Special attention is devoted to the evolution of the iterative processes, which is controlled by means of a tunable 'cooling' parameter. The difficulty of such 3D reconstructions is discussed with emphasis on attenuation problems that are typical in eddy current analysis.

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Section: Initialization and Cooling Schemesmentioning

confidence: 99%

“…Such tubes must be carefully controlled in order to ensure both the safety and the reliability of a nuclear power plant. Currently applied techniques are by means of ultrasonic and eddy current probes, and much work has in particular been devoted during these last few years [1][2][3][4][5][6][7][8] to the topic of eddy current evaluation.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional inversion of eddy current data for non-destructive evaluation of steam generator tubes

1998

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“…Examples include excitation and detection coils for micro nuclear magnetic resonance (NMR) spectroscopy [1]- [4], read/write heads for magnetic data storage [5], [6], sensors for measuring magnetic fields [7]- [10] and for detecting flaws in materials [11]- [13], micropositioners [14] and microactuators [15]- [17], and microinductors [18]- [21] and transformers [22]- [25]. Since microcoils for many of these applications incorporate wires with diameters less than 100 m, construction of these coils is not straightforward.…”

Section: Introductionmentioning

confidence: 99%

Constructing single- and multiple-helical microcoils and characterizing their performance as components of microinductors and microelectromagnets

Rogers¹,

Jackman

Whitesides

1997

J. Microelectromech. Syst.

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This paper describes a means for producing singleand multiple-helical microcoils by using microcontact printing to print lines on cylinders. This method was used to fabricate coils made of wires with widths and spaces between 150-25 m wrapped around cylinders with diameters between 100-400 m. Results show that microelectromagnets using these microcoils produce magnetic flux densities in excess of 0.4 T and can be switched on and off on a submillisecond time scale. [224]

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“…The sensor array was formed on a rigid substrate by photolithography. There are several other applications of a microloop inductive magnetic sensor to the ECT for stainless steel tubing [6] and aircraft engine [7].…”

Section: Introductionmentioning

confidence: 99%

Eddy-current testing by flexible microloop magnetic sensor array

et al. 1998

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A flexible microloop magnetic sensor array has been developed for nondestructive evaluation in nuclear power plants and its fundamental characteristics have been investigated. A flexible micro-eddy current testing (micro-ECT) probe consists of a pancake-type exciting coil of the diameter of 3.2 m and a flexible microloop magnetic sensor array with an area of 14 2 14 mm 2 and a thickness of 125 m. The array has 16 microloop sensors made of copper formed on a flexible polyimide film by sophisticated photolithography. Each coil has 40 turns (8 m line and 8 m space) within an area of 2 2 2 mm 2 . The flexible sensorarray enables the micro-ECT probe to be applied to an arbitrary geometric configuration. The purpose of this work is to detect and reconstruct flaws in conductive tubing of a steam generator in a pressurized nuclear power reactor by using the flexible micro-ECT probe with higher spatial resolution than that of a conventional ECT probe. The spatial resolution of flaw detection was 3 mm and the detectability of an outer 20% flaw made by electric discharge machining was confirmed. The reconstruction of circumferential and axial flaws using the electromotive force and phase measured with the sensor array is described. Threedimensional eddy current and magnetic field analysis was also performed for comparison with measured data. Finally, a design study of a practical and robust micro-ECT for a realistic tube configuration with respect to detectability was carried out.

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Data acquisition for experimental verification of an eddy current model for three dimensional inversion

Cited by 10 publications

References 4 publications

Three-dimensional inversion of eddy current data for non-destructive evaluation of steam generator tubes

Three-dimensional inversion of eddy current data for non-destructive evaluation of steam generator tubes

Constructing single- and multiple-helical microcoils and characterizing their performance as components of microinductors and microelectromagnets

Eddy-current testing by flexible microloop magnetic sensor array

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