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.

scholarly journals Convergence of the uniaxial PML method for time-domain electromagnetic scattering problems

2021 ◽  
Author(s):  
Changkun Wei ◽  
Jiaqing Yang ◽  
Bo Zhang
Keyword(s):  
Time Domain ◽  
Electromagnetic Scattering ◽  
Scattering Problem ◽  
Three Dimensional ◽  
Scattering Problems ◽  
Laplace Transform Technique ◽  
The Laplace Transform ◽  
Time Domain Electromagnetic ◽  
Numer Anal ◽  
The Time Domain

In this paper, we propose and study the uniaxial perfectly matched layer (PML) method for three-dimensional time-domain electromagnetic scattering problems, which has a great advantage over the spherical one in dealing with problems involving anisotropic scatterers. The truncated uniaxial PML problem is proved to be well-posed and stable, based on the Laplace transform technique and the energy method. Moreover, the $L^2$-norm and $L^{\infty}$-norm error estimates in time are given between the solutions of the original scattering problem and the truncated PML problem, leading to the exponential convergence of the time-domain uniaxial PML method in terms of the thickness and absorbing parameters of the PML layer. The proof depends on the error analysis between the EtM operators for the original scattering problem and the truncated PML problem, which is different from our previous work (SIAM J. Numer. Anal. 58(3) (2020), 1918-1940).

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.

DEEP STRUCTURE OF THE FAULT ZONE IN THE MUKHOR-TARKATA SITE OF THE CHUYA DEPRESSION ACCORDING TO NON-STATIONARY ELECTROMAGNETIC SOUNDING DATA USING THREE-DIMENSIONAL MODELING

2021 ◽  
pp. 67-73
Author(s):  
A. M. Sanchaa ◽  
◽  
N. N. Nevedrova ◽  
N. V. Shtabel ◽  
◽  
...  
Keyword(s):  
Fault Zone ◽  
Time Domain ◽  
Deep Structure ◽  
Near Field ◽  
Three Dimensional ◽  
Structural Features ◽  
Electromagnetic Sounding ◽  
Three Dimensional Modeling ◽  
Dimensional Modeling ◽  
Time Domain Electromagnetic

The paper presents the results of three-dimensional modeling of the fault structure in the central part of the Chuya depression in Gornyi Altai within the Mukhor-Tarkhata plot. On this site, from 2004 to the present, researchers of the IPGG SB RAS have been conducting regular annual observations by the method of nearfield time-domain electromagnetic sounding (TSB) to observe the process of restoration of the geological environment after the catastrophic Chuya earthquake with a magnitude of 7.3 in 2003. One of the aftereffects of the destructive earthquake is fracture zones expressed on the surface. Numerous deformations of the surface and industrial objects are observed in the area of the Mukhor-Tarkhata village. The fault zone with sub-vertical fracturing, identified at the site by geological and electromagnetic data, was activated after the earthquake. Detailed data on the geoelectric structure are required for the interpretation and analysis of monitoring data. Based on the interpretation of the near-field time-domain electromagnetic sounding data, the deep structure of the fault zone was obtained. To verify and clarify structural features of the geoelectric model, three-dimensional modeling was performed.

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.

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