Vertical electric source in transient marine CSEM: Effect of 3D inhomogeneities on the late time response

Geophysics ◽  
2013 ◽  
Vol 78 (4) ◽  
pp. E173-E188 ◽  
Author(s):  
Bension Sh. Singer ◽  
Svetlana Atramonova
Keyword(s):  
Electromagnetic Field ◽  
Electric Field ◽  
Numerical Solutions ◽  
Closed Form Solution ◽  
Time Response ◽  
Stratified Medium ◽  
Late Time ◽  
Fast Decay ◽  
Parallel Shift ◽  
Vertical Electric Field

The time-domain marine controlled-source electromagnetic method, based on injection of electric currents into the sea via a vertical cable and measurements of the transient vertical electric field, is characterized by high sensitivity to resistive reservoirs and robustness with respect to distorting effects of lateral heterogeneities. This is due to the fact that a vertical electric dipole induces in a stratified medium only a transverse magnetic (TM) field. In addition, the vertical electric field is not directly contributed by the transverse electric (TE) component of the field scattered by heterogeneities. Nevertheless, a closed-form solution shows that the first order effect of a lateral heterogeneity displays itself as a parallel shift of the late time response curves. The effect is also observed in 3D responses evaluated by numerical solutions of the integral equation of the modified iterative dissipative method. Moreover, in “favorable” conditions, scattering on heterogeneities may change the law of the field decay. The parallel shift of the late time curves is caused by vertical polarization of the scatterer, while its horizontal polarization leads to an abnormally fast decay of the vertical electric field. The latter effect, observed against the background of the general decay of the free electromagnetic field, can be associated with “energy channeling from the TM to TE field.” Neither of the effects necessarily deteriorates the method sensitivity. Unlike the vertical electric field, the horizontal electromagnetic field is contributed by the scattered TE field. As a result, the abnormally fast decay of the vertical electric field is accompanied by an abnormally slow decay of the horizontal components. The transient horizontal electric field may become almost insensitive to the reservoir resistivity. In addition to unrealistically harsh requirements to the transmitter tilt, this may render accurate measurements of the horizontal electromagnetic field of a vertical electric bipole not feasible.

scholarly journals Focused Patterning of Electrospun Nanofibers Using a Dielectric Guide Structure

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1505
Author(s):  
Byeongjun Lee ◽  
Younghyeon Song ◽  
Chan Park ◽  
Jungmin Kim ◽  
Jeongbeom Kang ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Finite Elements ◽  
Electric Field ◽  
Electrospun Nanofibers ◽  
Electrospun Fibers ◽  
Continuous Line ◽  
Key Factors ◽  
Key Technology ◽  
Vertical Electric Field ◽  
Dielectric Guide

The patterning of electrospun fibers is a key technology applicable to various fields. This study reports a novel focused patterning method for electrospun nanofibers that uses a cylindrical dielectric guide. The finite elements method (FEM) was used to analyze the electric field focusing phenomenon and ground its explanation in established theory. The horizontal and vertical electric field strengths in the simulation are shown to be key factors in determining the spatial distribution of nanofibers. The experimental results demonstrate a relationship between the size of the cylindrical dielectric guide and that of the electrospun area accumulated in the collector. By concentrating the electric field, we were able to fabricate a pattern of less than 6 mm. The demonstration of continuous line and square patterning shows that the electrospun area can be well controlled. This novel patterning method can be used in a variety of applications, such as sensors, biomedical devices, batteries, and composites.

scholarly journals An augmented Lagrangian method for solving total variation (TV)-based image registration model

2020 ◽  
Vol 14 ◽  
pp. 174830262097353
Author(s):  
Noppadol Chumchob ◽  
Ke Chen
Keyword(s):  
Image Registration ◽  
Augmented Lagrangian ◽  
Numerical Solutions ◽  
Augmented Lagrangian Method ◽  
Closed Form Solution ◽  
Numerical Algorithms ◽  
Lagrangian Method ◽  
Form Solution ◽  
The Other ◽  
Other Hand

Variational methods for image registration basically involve a regularizer to ensure that the resulting well-posed problem admits a solution. Different choices of regularizers lead to different deformations. On one hand, the conventional regularizers, such as the elastic, diffusion and curvature regularizers, are able to generate globally smooth deformations and generally useful for many applications. On the other hand, these regularizers become poor in some applications where discontinuities or steep gradients in the deformations are required. As is well-known, the total (TV) variation regularizer is more appropriate to preserve discontinuities of the deformations. However, it is difficult in developing an efficient numerical method to ensure that numerical solutions satisfy this requirement because of the non-differentiability and non-linearity of the TV regularizer. In this work we focus on computational challenges arising in approximately solving TV-based image registration model. Motivated by many efficient numerical algorithms in image restoration, we propose to use augmented Lagrangian method (ALM). At each iteration, the computation of our ALM requires to solve two subproblems. On one hand for the first subproblem, it is impossible to obtain exact solution. On the other hand for the second subproblem, it has a closed-form solution. To this end, we propose an efficient nonlinear multigrid (NMG) method to obtain an approximate solution to the first subproblem. Numerical results on real medical images not only confirm that our proposed ALM is more computationally efficient than some existing methods, but also that the proposed ALM delivers the accurate registration results with the desired property of the constructed deformations in a reasonable number of iterations.

Investigating flexible textile-based coils for wireless charging wearable electronics

2019 ◽  
Vol 50 (3) ◽  
pp. 333-345 ◽  
Author(s):  
Danmei Sun ◽  
Meixuan Chen ◽  
Symon Podilchak ◽  
Apostolos Georgiadis ◽  
Qassim S Abdullahi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electrical Conductivity ◽  
Electromagnetic Field ◽  
Electric Field ◽  
Dimensional Stability ◽  
Screen Printing ◽  
Wearable Electronics ◽  
Wireless Charging ◽  
The Magnetic Field ◽  
Screen Printed

Smart and interactive textiles have been attracted great attention in recent years. This research explored three different techniques and processes in developing textile-based conductive coils that are able to embed in a garment layer. Coils made through embroidery and screen printing have good dimensional stability, although the resistance of screen printed coil is too high due to the low conductivity of the print ink. Laser cut coil provided the best electrical conductivity; however, the disadvantage of this method is that it is very difficult to keep the completed coil to the predetermined shape and dimension. The tested results show that an electromagnetic field has been generated between the textile-based conductive coil and an external coil that is directly powered by electricity. The magnetic field and electric field worked simultaneously to complete the wireless charging process.

Reduced interfacial fluctuation leading enhanced mobility in a monolayer MoS2 DG FET under low vertical electric field

2019 ◽  
Vol 30 (34) ◽  
pp. 345206 ◽  
Author(s):  
Hyunjin Ji ◽  
Hojoon Yi ◽  
Sakong Wonkil ◽  
Hyun Kim ◽  
Seong Chu Lim
Keyword(s):  
Electric Field ◽  
Monolayer Mos2 ◽  
Vertical Electric Field ◽  
Enhanced Mobility

SOLITARY WAVES OF THE NONLINEAR KLEIN-GORDON EQUATION COUPLED WITH THE MAXWELL EQUATIONS

2002 ◽  
Vol 14 (04) ◽  
pp. 409-420 ◽  
Author(s):  
VIERI BENCI ◽  
DONATO FORTUNATO FORTUNATO
Keyword(s):  
Electromagnetic Field ◽  
Solitary Wave ◽  
Electric Field ◽  
Solitary Waves ◽  
Maxwell Equations ◽  
Gordon Equation ◽  
Klein Gordon ◽  
Klein Gordon Equation

This paper is divided in two parts. In the first part we construct a model which describes solitary waves of the nonlinear Klein-Gordon equation interacting with the electromagnetic field. In the second part we study the electrostatic case. We prove the existence of infinitely many pairs (ψ, E), where ψ is a solitary wave for the nonlinear Klein-Gordon equation and E is the electric field related to ψ.

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