Electromagnetic response of an arbitrarily shaped three-dimensional conductor in a layered earth -- numerical results

Das, U. C.; Verma, Saurabh

doi:10.1111/j.1365-246x.1982.tb04935.x

Cited by 14 publications

(16 citation statements)

References 17 publications

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“…Only during the last 2 yr did the first results for the brick in a two-layered earth appear (Hvozdara, 1981b;Wannamaker and Hohmann, 1982;Das and Verma, 1982).…”

Section: Integral Equation Methods (Ie)mentioning

confidence: 94%

“…The first set of tests models was adopted by international conferences in Australia (Sydney, 1977) andU.S.A. (Berkeley, 1978) and the results of several comparative calculations were published recently (Pridmore et at., 1981, Das andVerma, 1982;etc).…”

Section: Practical Problems Of 3d Modellingmentioning

confidence: 93%

“…Hvozdara (1981b) achieved rapid convergence for contrasts of about 100 (with an improved initial approximation). There are several examples of the use of direct (elimination) methods Das and Verma, 1982;Wannamaker and Hohmann, 1982). Also the approach of approximate reduction of the filled matrix to the banded form seems to be interesting (Poggio and Miller, 1973).…”

Section: Linear System Solutionmentioning

confidence: 98%

“…This class is of great importance in theoretical and methodical 3D investigations (Cauterman et at., 1979;Stodt et at., 1981 ;Sandberg and Hohmann, 1982;Das and Verma, 1982). A new generation of cost effective computer programs dealing with multi-layered models containing several inclusions with an arbitrary conductivity distribution is now appearing (Wannamaker and Hohmann, 1982;Das and Verma, 1982).…”

Section: Practical Problems Of 3d Modellingmentioning

confidence: 99%

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Modern trends in the solution of forward and inverse 3D electromagnetic induction problems

Варенцов

1983

Geophysical Surveys

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Abstract. The main results obtained during the last 5-8 yr in the solution of forward and inverse problems of 3D induction studies are summarized. The up-to-date status of 3D modelling is presented and prospective improvements in the formulation and numerical solution of forward problems are discussed. Approximate techniques and practical aspects of 3D modelling are specially considered.The general scheme of 3D interpretation of electromagnetic geophysical observations is outlined and realistic formalized approaches to solving 3D inverse problems, namely direct inversion and formalized model fitting, are studied. O. IntroductionThe significant progress in the development of electromagnetic (EM) array observations achieved during the last ten years made it necessary to elaborate the system of EM data interpretation in 3D environments. Theoretical studies of 3D problems have been carried out during the last twenty years or more, but not until a few years ago did these works become of practical importance and serious applied researches were begun. Now many publications concerned with 3D induction studies are well known. Still, we have no generalized reviews on this subject (except brief ones like Ward, 1980), but in many special papers meaningful discussions of the problems and outlines of 3D techniques have been presented (Weidelt, 1975a;Vasseur and Weidelt, 1977;Hohmann, 1978;Banks, 1979;Weaver, 1979;Dawson and Weaver, 1979, Fainberg, 1980;Lee et al., 1981;Stodt et al., 1981;Berdichevsky et al., 1982; etc).It looks quite unrealistic to consider in detail the significant achievements in all of the numerous branches of 3D induction studies in a single review. Therefore the subject of this paper is restricted to the study of interpretation techniques of time-harmonic EM field anomalies caused by local and regional 3D conductivity structures. Moreover, attention is paid mainly to the theoretical and computational aspects of the rational formulation and effective solution of 3D forward and inverse problems. These problems form the basis of the interpretation theory and, as it can be seen from the experience of 2D induction studies, their intensive development produces the evident progress in elaboration of the whole interpretation system. It is not surprising that these problems are prevalent in the majority of publications of recent years.It should be noted that general ideas of inhomogeneous media interpretation theory, well illustrated in 2D applications, can be expressed in the main in 3D formulations. This has been shown clearly in the last monographs of Zhdanov (1981, 1983). However, we have usually enough difficulties to overcome in the theoretical analysis and at the stage of numerical considerations. Really, in most 3D

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“…Only during the last 2 yr did the first results for the brick in a two-layered earth appear (Hvozdara, 1981b;Wannamaker and Hohmann, 1982;Das and Verma, 1982).…”

Section: Integral Equation Methods (Ie)mentioning

confidence: 94%

Section: Practical Problems Of 3d Modellingmentioning

confidence: 93%

Section: Linear System Solutionmentioning

confidence: 98%

Section: Practical Problems Of 3d Modellingmentioning

confidence: 99%

See 2 more Smart Citations

Modern trends in the solution of forward and inverse 3D electromagnetic induction problems

Варенцов

1983

Geophysical Surveys

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“…Recently Das and Verma (1982) and Wannamaker and Hohmann (1983) presented numerical results, based on similar volume integral equation solutions, for a 3D body in a layered earth. The former results are for magnetic dipole excitation and the latter for plane wave excitation.…”

Section: Integral Equation Solutionsmentioning

confidence: 99%

Three-dimensional em modeling

Hohmann

1983

Geophysical Surveys

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Abstract. Three-dimensional (3D) interpretation of electromagnetic (EM) dsta is still in its infancy, due to a lack of practical numerical solutions for the forward problem. However, a number of algorithms for simulating the responses of simple 3D models have been developed over the last ten years, and they have provided important new insight. Integral equation methods have been more successful than differential equation methods, because they require calculating the electric field only in small anomalous regions, rather than throughout the earth. Utilizing a vector-scalar potential approach and incorporating symmetry through group theory improves the general 3D integral equation solution. Thin-sheet integral equation formulations have been particularly useful. Much recent research has focused on hybrid methods, which are finite element differential equation solutions within a mesh of limited extent, with boundary values determined by integrating over the interior fields. An elegant eigencurrent technique has been developed for calculating the transient response of a thin 3D sheet in free space, but general 3D time domain responses have only been calculated by Fourier transforming frequency domain results. Direct time domain calculations have been carried out only for 2D bodies.

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The volume integral method of eddy current modeling

Dunbar

1985

J Nondestruct Eval

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Electromagnetic response of an arbitrarily shaped three-dimensional conductor in a layered earth -- numerical results

Cited by 14 publications

References 17 publications

Modern trends in the solution of forward and inverse 3D electromagnetic induction problems

Modern trends in the solution of forward and inverse 3D electromagnetic induction problems

Three-dimensional em modeling

The volume integral method of eddy current modeling

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