QUASI‐STATIC TIME‐DOMAIN ELECTROMAGNETIC RESPONSE OF A HOMOGENEOUS CONDUCTING INFINITE CYLINDER

Geophysics ◽  
1972 ◽  
Vol 37 (1) ◽  
pp. 92-97 ◽  
Author(s):  
Saurabh K. Verma
Keyword(s):  
Time Domain ◽  
Decay Constant ◽  
Step Function ◽  
Ore Deposits ◽  
Electromagnetic Response ◽  
Infinite Cylinder ◽  
Transient Electromagnetic ◽  
Simplifying Assumptions ◽  
Time Domain Electromagnetic ◽  
Theoretical Results

Under some simplifying assumptions, the transient electromagnetic response of a homogeneous conducting infinite cylinder is derived. Two types of primary disturbances, represented by step‐function and ramp‐function pulses, are considered. Based on the theoretical results, response and decay constant curves are plotted and their utility in time‐domain electromagnetic surveys for conductive elongated ore deposits is described.

TIME‐DEPENDENT ELECTROMAGNETIC FIELDS OF AN INFINITE, CONDUCTING CYLINDER EXCITED BY A LONG CURRENT‐CARRYING CABLE

Geophysics ◽  
1973 ◽  
Vol 38 (2) ◽  
pp. 369-379 ◽  
Author(s):  
Saurabh K. Verma
Keyword(s):  
Time Domain ◽  
Horizontal Cylinder ◽  
The Body ◽  
Time Dependent ◽  
Electromagnetic Response ◽  
Secondary Field ◽  
Function Type ◽  
Ore Body ◽  
Induced Field ◽  
Time Domain Electromagnetic

Theoretical and numerical computations have been made for the quasi‐static, time‐domain electromagnetic response of an infinite, conducting horizontal cylinder stimulated by long cable‐carrying step and ramp‐function type pulses. The effect of higher‐order induced multipoles on the secondary electric and magnetic field components is analyzed in detail, and the “threshold distances” at which individual multipoles become effective (contributing more than 5 percent of the secondary field) are presented. Also, the field fall‐off directly above the body and the variations in different induced‐field components along a traverse perpendicular to the strike of the ore body are examined.

Three-dimensional transient electromagnetic inversion with optimal transport

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Xiaomeng Sun ◽  
Yanfei Wang ◽  
Xiao Yang ◽  
Yibo Wang
Keyword(s):  
Time Domain ◽  
3D Model ◽  
Optimal Transport ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Transient Electromagnetic Method ◽  
Inversion Problem ◽  
Wasserstein Metric ◽  
Transient Electromagnetic ◽  
Time Domain Electromagnetic

Abstract Transient electromagnetic method (TEM), as one of the essential time-domain electromagnetic prospecting approaches, has the advantage of expedition, efficiency and convenience. In this paper, we study the transient electromagnetic inversion problem of different geological anomalies. First, Maxwell’s differential equations are discretized by the staggered finite-difference (FD) method; then we propose to solve the TEM inversion problem by minimizing the Wasserstein metric, which is related to the optimal transport (OT). Experimental tests based on the layered model and a 3D model are performed to demonstrate the feasibility of our proposed method.

Direct inversion of time‐domain electromagnetic data

Geophysics ◽  
1987 ◽  
Vol 52 (10) ◽  
pp. 1431-1435 ◽  
Author(s):  
A. G. Nekut
Keyword(s):  
Least Squares ◽  
Time Domain ◽  
Time Derivative ◽  
Image Method ◽  
Simple Method ◽  
Geoelectric Section ◽  
Direct Inversion ◽  
Transient Electromagnetic ◽  
Time Domain Electromagnetic ◽  
Central Loop

This note describes a simple method for converting transient electromagnetic (EM) sounding data into profiles of conductivity versus depth, based on an approximate image representation for the decaying induced ground currents. The method can provide one‐dimensional (1-D) inversion for any kind of time‐domain EM sounding data; the discussion here is limited to the case of central‐loop sounding. In particular, I apply the inversion to some time‐derivative central‐loop sounding data and demonstrate that essentially the same interpretation of the geoelectric section is obtained with the simple image method as is obtained using traditional iterative least‐squares fitting to layered models. This simple inverse can be computed much more quickly than an iterative least‐squares inverse, making it possible to estimate the geoelectric section concomitant with data acquisition.

scholarly journals Identification of dominant error parameters in spectrum measured by TDEMI system

ACTA IMEKO ◽  
2015 ◽  
Vol 4 (1) ◽  
pp. 61
Author(s):  
Miroslav Kamenský ◽  
Karol Kovác
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Time Domain ◽  
Electromagnetic Interference ◽  
Dynamic Range ◽  
Measuring Systems ◽  
Analog To Digital ◽  
Time Domain Electromagnetic ◽  
Parallel Input ◽  
Theoretical Results

Multiresolution analog-to-digital converters (MRADC) are usually used in Time Domain ElectroMagnetic Interference (TDEMI) measuring systems for very fast signal sampling with a sufficient dynamic range. The properties of the spectrum measured by the TDEMI system influenced by imperfections in the MRADC are analyzed in this paper. Errors are caused by imperfect matching of the offset and gain and phase of the circuits used in parallel input channels typical for the MRADC. For deep analyses of MRADC behavior, a precise mathematical model has been created using the concept of additive error pulses. Furthermore, a dedicated process of the identification of discrepancy parameters from experimental data is proposed. Identified parameters enter the expressions of the model and enable side to side comparison of experimental and theoretical results.

The time-domain electromagnetic response of wedge-like structures

2004 ◽  
Vol 2004 (1) ◽  
pp. 1-4
Author(s):  
David Annetts ◽  
Art Raiche ◽  
Fred Sugeng
Keyword(s):  
Time Domain ◽  
Electromagnetic Response ◽  
Time Domain Electromagnetic ◽  
The Time Domain
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