Download or read book Isotropic and Anisotropic Three dimensional Inversion of Frequency domain Controlled source Electromagnetic Data Using Finite Element Techniques written by Feiyan Wang and published by . This book was released on 2016 with total page 117 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Two dimensional Modeling and Inversion of the Controlled source Electromagnetic and Magnetotelluric Methods Using Finite Elements and Full space PDE constrained Optimization Strategies written by Savitri Galiana Blanch and published by . This book was released on 2016 with total page 265 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The controlled-source electromagnetics (CSEM) and magnetotellurics (MT) methods arecommon geophysical tools for imaging the electrical properties of the Earth's subsurfaceand are employed independently, jointly, and in combination with other geophysical tech-niques. In order to appreciate measured data, both methods require forward and inversemodeling of the electrically conductive subsurface with the ultimate goal of finding a fea-sible model for which the simulated data reasonably fits the observations. Naturally, thepotential goodness of this fit not only depends on the error in the measured data and on thenumerical error but also on the degree of physical approximation inferred by numericalmodeling. Therefore, active research focuses on new methods for modeling and inversionto obtain accurate and reliable models of the Earth's structure in increasingly complexscenarios. A first step is to enhance modeling approximations by taking into account physical fac-tors such as anisotropy, topography or realistic sources. Second, in order to accommodatethese factors in a modeling and inversion program and to deal with typically large datasets, numerical methods need to be assessed in terms of solution accuracy, time efficiencyand memory demand. The finite elements (FE) modeling methods are known to offer mostflexibility in model geometry and contain quality control mechanisms for the solution, likeshape function order and adaptive mesh refinement. Most emerging modeling programsare based on FE, appreciating significant advantages, but nearly all inverse modeling pro-grams to date are still based on finite differences (FD) or integral equation (IE) methods. Furthermore, inverse modeling developed for electromagnetic (EM) data is generallybased on gradient methods and is formulated in a reduced space, where the only optimiza-tion variables are the model parameters, that is the electric conductivity of the subsurface. Originally, the inverse problem is stated for the EM fields and the conductivity parameter, and constrained by partial differential equations (PDEs) governing the EM field variables. The reduced-space strategy eliminates the field variables by applying equality constraintsand solving then, the unconstrained problem in the reduced-space of model parameters. Acommon drawback of such methods is the repeated costly computation of the solution ofthe forward problem and of the Jacobian matrix of sensitivities (for Newton's based meth-ods). In contrast, it is also possible to solve the inverse problem in the full-space of modelparameters, including both the EM field variables and the electric conductivity parameter. Solving the PDE-constrained optimization problem directly (full-space) has the advantagethat it is only necessary to solve exactly the PDEs at the very end of the optimization provicess but it comes at the cost of many more optimization variables and of the presence ofequality constraints. Also, in particular, within a FE framework, the PDE-constrained op-timization problem provides the additional benefit to include sophisticated FE techniquesin the inversion process, such as adaptive mesh refinement. This thesis develops a robust and versatile adaptive unstructured mesh FE programto numerically model the total field for two-dimensional (2-D) anisotropic CSEM and MTdata, allowing for arbitrarily oriented, three-dimensional (3-D) sources. To represent 3-DCSEM sources for a 2-D physical model, a two-and-a-half-dimensional (2.5-D) approxi-mation is employed. The FE formulations are derived for both methods, for isotropic andanisotropic subsurface conductivity structures. Although the anisotropic case is not general, it includes vertical and dipping anisotropy. The accuracy of the solution is controlledand improved by an adaptive mesh refinement algorithm usinga-posteriorierror estimator methods."--TDX.
Download or read book Geophysics Today written by Sergey Fomel and published by SEG Books. This book was released on 2010 with total page 543 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presents a collection of papers which appear in the September-October 2010 Geophysics special section, written by recognised experts in various areas of exploration geophysics, plus an additional group of papers drawn from Geophysics which address areas beyond those invited articles. The result is a snapshot of the state-of-the-art in the field.
Download or read book Double Grid Finite Difference Frequency Domain DG FDFD Method for Scattering from Chiral Objects written by Erdogan Alkan and published by Springer Nature. This book was released on 2022-05-31 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the application of the overlapping grids approach to solve chiral material problems using the FDFD method. Due to the two grids being used in the technique, we will name this method as Double-Grid Finite Difference Frequency-Domain (DG-FDFD) method. As a result of this new approach the electric and magnetic field components are defined at every node in the computation space. Thus, there is no need to perform averaging during the calculations as in the aforementioned FDFD technique [16]. We formulate general 3D frequency-domain numerical methods based on double-grid (DG-FDFD) approach for general bianisotropic materials. The validity of the derived formulations for different scattering problems has been shown by comparing the obtained results to exact and other solutions obtained using different numerical methods. Table of Contents: Introduction / Chiral Media / Basics of the Finite-Difference Frequency-Domain (FDFD) Method / The Double-Grid Finite-Difference Frequency-Domain (DG-FDFD) Method for Bianisotropic Medium / Scattering FromThree Dimensional Chiral Structures / ImprovingTime and Memory Efficiencies of FDFD Methods / Conclusions / Appendix A: Notations / Appendix B: Near to Far FieldTransformation
Download or read book Petroleum Abstracts written by and published by . This book was released on 1993 with total page 1752 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Three dimensional Inversion of Frequency Domain Airborne Electromagnetic Data written by Leif Harrington Cox and published by . This book was released on 2007 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Finite Element Method in Electromagnetics written by Jian-Ming Jin and published by John Wiley & Sons. This book was released on 2015-02-18 with total page 728 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new edition of the leading textbook on the finite element method, incorporating major advancements and further applications in the field of electromagnetics The finite element method (FEM) is a powerful simulation technique used to solve boundary-value problems in a variety of engineering circumstances. It has been widely used for analysis of electromagnetic fields in antennas, radar scattering, RF and microwave engineering, high-speed/high-frequency circuits, wireless communication, electromagnetic compatibility, photonics, remote sensing, biomedical engineering, and space exploration. The Finite Element Method in Electromagnetics, Third Edition explains the method’s processes and techniques in careful, meticulous prose and covers not only essential finite element method theory, but also its latest developments and applications—giving engineers a methodical way to quickly master this very powerful numerical technique for solving practical, often complicated, electromagnetic problems. Featuring over thirty percent new material, the third edition of this essential and comprehensive text now includes: A wider range of applications, including antennas, phased arrays, electric machines, high-frequency circuits, and crystal photonics The finite element analysis of wave propagation, scattering, and radiation in periodic structures The time-domain finite element method for analysis of wideband antennas and transient electromagnetic phenomena Novel domain decomposition techniques for parallel computation and efficient simulation of large-scale problems, such as phased-array antennas and photonic crystals Along with a great many examples, The Finite Element Method in Electromagnetics is an ideal book for engineering students as well as for professionals in the field.
Download or read book Double Grid Finite Difference Frequency Domain DG FDFD Method for Scattering from Chiral Objects written by Erdogan Alkan and published by Morgan & Claypool Publishers. This book was released on 2013-01-01 with total page 131 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the application of the overlapping grids approach to solve chiral material problems using the FDFD method. Due to the two grids being used in the technique, we will name this method as Double-Grid Finite Difference Frequency-Domain (DG-FDFD) method. As a result of this new approach the electric and magnetic field components are defined at every node in the computation space. Thus, there is no need to perform averaging during the calculations as in the aforementioned FDFD technique [16]. We formulate general 3D frequency-domain numerical methods based on double-grid (DG-FDFD) approach for general bianisotropic materials. The validity of the derived formulations for different scattering problems has been shown by comparing the obtained results to exact and other solutions obtained using different numerical methods. Table of Contents: Introduction / Chiral Media / Basics of the Finite-Difference Frequency-Domain (FDFD) Method / The Double-Grid Finite-Difference Frequency-Domain (DG-FDFD) Method for Bianisotropic Medium / Scattering FromThree Dimensional Chiral Structures / ImprovingTime and Memory Efficiencies of FDFD Methods / Conclusions / Appendix A: Notations / Appendix B: Near to Far FieldTransformation
Download or read book Electromagnetic Methods in Applied Geophysics written by Misac N. Nabighian and published by SEG Books. This book was released on 1988 with total page 989 pages. Available in PDF, EPUB and Kindle. Book excerpt: As a slag heap, the result of strip mining, creeps closer to his house in the Ohio hills, fifteen-year-old M. C. is torn between trying to get his family away and fighting for the home they love.
Download or read book Multiresolution Frequency Domain Technique for Electromagnetics written by Mesut Gökten and published by Springer Nature. This book was released on 2022-06-01 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this book, a general frequency domain numerical method similar to the finite difference frequency domain (FDFD) technique is presented. The proposed method, called the multiresolution frequency domain (MRFD) technique, is based on orthogonal Battle-Lemarie and biorthogonal Cohen-Daubechies-Feauveau (CDF) wavelets. The objective of developing this new technique is to achieve a frequency domain scheme which exhibits improved computational efficiency figures compared to the traditional FDFD method: reduced memory and simulation time requirements while retaining numerical accuracy. The newly introduced MRFD scheme is successfully applied to the analysis of a number of electromagnetic problems, such as computation of resonance frequencies of one and three dimensional resonators, analysis of propagation characteristics of general guided wave structures, and electromagnetic scattering from two dimensional dielectric objects. The efficiency characteristics of MRFD techniques based on different wavelets are compared to each other and that of the FDFD method. Results indicate that the MRFD techniques provide substantial savings in terms of execution time and memory requirements, compared to the traditional FDFD method. Table of Contents: Introduction / Basics of the Finite Difference Method and Multiresolution Analysis / Formulation of the Multiresolution Frequency Domain Schemes / Application of MRFD Formulation to Closed Space Structures / Application of MRFD Formulation to Open Space Structures / A Multiresolution Frequency Domain Formulation for Inhomogeneous Media / Conclusion
Download or read book A Finite Element Approach to the 3D CSEM Modeling Problem and Applications to the Study of the Effect of Target Interaction and Topography written by Jack Stalnaker and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The solution of the secondary coupled-vector potential formulation of Maxwell's equations governing the controlled-source electromagnetic (CSEM) response of an arbitrary, three-dimensional conductivity model must be calculated numerically. The finite element method is attractive, because it allows the model to be discretized into an unstructured mesh, permitting the specification of realistic irregular conductor geometries, and permitting the mesh to be refined locally, where finer resolution is needed. The calculated results for a series of simple test problems, ranging from one-dimensional scalar differential equations to three-dimensional coupled vector equations match the known analytic solutions well, with error values several orders of magnitude smaller than the calculated values. The electromagnetic fields of a fully three-dimensional CSEM model, recovered from the potentials using the moving least squares interpolation numerical differentiation algorithm, compares well with published numerical modeling results, particularly when local refinement is applied. Multiple buried conductors in a conductive host interact via mutual induction and current flow through the host due to the dissipation of charge accumulated on the conductor boundary. The effect of this interaction varies with host conductivity, transmitter frequency, and conductor geometry, orientation, and conductivity. For three test models containing two highly conductive plate-like targets, oriented in various geometries (parallel, perpendicular, and horizontal), mutual coupling ranges as high as twenty times the total magnetic field. The effect of varying host conductivity is significant, especially at high frequencies. Numerical modeling also shows that the vorticity of the currents density induced in a vertically oriented plate-like conductor rotates from vertical at high frequencies, to horizontal at low frequencies, a phenomenon confirmed by comparison with time domain field data collected in Brazos County, Texas. Furthermore, the effect of the presence of a simple horst on the CSEM response of a homogeneous conductive earth is significant, even when the height of the horst is only a fraction of the skin depth of the model. When the transmitter is placed on top of the horst, the currents induced therein account for nearly all of the total magnetic field of the model, indicating that topography, like mutual coupling must be accounted for when interpreting CSEM data.
Download or read book Introduction to the Finite Difference Time Domain FDTD Method for Electromagnetics written by Stephen Gedney and published by Springer Nature. This book was released on 2022-05-31 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introduction to the Finite-Difference Time-Domain (FDTD) Method for Electromagnetics provides a comprehensive tutorial of the most widely used method for solving Maxwell's equations -- the Finite Difference Time-Domain Method. This book is an essential guide for students, researchers, and professional engineers who want to gain a fundamental knowledge of the FDTD method. It can accompany an undergraduate or entry-level graduate course or be used for self-study. The book provides all the background required to either research or apply the FDTD method for the solution of Maxwell's equations to practical problems in engineering and science. Introduction to the Finite-Difference Time-Domain (FDTD) Method for Electromagnetics guides the reader through the foundational theory of the FDTD method starting with the one-dimensional transmission-line problem and then progressing to the solution of Maxwell's equations in three dimensions. It also provides step by step guides to modeling physical sources, lumped-circuit components, absorbing boundary conditions, perfectly matched layer absorbers, and sub-cell structures. Post processing methods such as network parameter extraction and far-field transformations are also detailed. Efficient implementations of the FDTD method in a high level language are also provided. Table of Contents: Introduction / 1D FDTD Modeling of the Transmission Line Equations / Yee Algorithm for Maxwell's Equations / Source Excitations / Absorbing Boundary Conditions / The Perfectly Matched Layer (PML) Absorbing Medium / Subcell Modeling / Post Processing
Download or read book Three Dimensional Finite Element Method Applied to Study the Penetration of Electromagnetic Fields in Cavities written by Darcy N. Ladd and published by . This book was released on 1990 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: A three dimensional formulation of the finite element method was developed to solve the electromagnetic field distribution in an arbitrary region containing conducting and dielectric materials when the tangential magnetic field was known at the boundaries. The formulation was developed using a three component vector magnetic potential and a scalar electric potential. The displacement current as well as the conduction current term was accounted for. The region of interest was discretized using eight node isoparametric hexahedrons and the potential functions were defined using linear first order basis functions. The frequency domain finite element method program was validated by comparison with closed form solutions for simplified geometries. The algorithm proved to have a convergent solution when solving the diffusion of electromagnetic fields into conducting hollow and solid structures without apertures. The penetration of a steady-state electromagnetic field through an aperture into a simple cavity was analyzed with the 3-D FEM program. The diffusion of a step-impulse magnetic filed into a conducting slab was solved directly in the time domain with a time domain finite element program. Conclusions were drawn on the feasibility of using the finite element method as part of an EMI/EMC CAD package.
Download or read book Automated Solution of Differential Equations by the Finite Element Method written by Anders Logg and published by Springer Science & Business Media. This book was released on 2012-02-24 with total page 723 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a tutorial written by researchers and developers behind the FEniCS Project and explores an advanced, expressive approach to the development of mathematical software. The presentation spans mathematical background, software design and the use of FEniCS in applications. Theoretical aspects are complemented with computer code which is available as free/open source software. The book begins with a special introductory tutorial for beginners. Following are chapters in Part I addressing fundamental aspects of the approach to automating the creation of finite element solvers. Chapters in Part II address the design and implementation of the FEnicS software. Chapters in Part III present the application of FEniCS to a wide range of applications, including fluid flow, solid mechanics, electromagnetics and geophysics.
Download or read book Finite Elements for Wave Electromagnetics written by IEEE Antennas and Propagation Society and published by Institute of Electrical & Electronics Engineers(IEEE). This book was released on 1994 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Three dimensional Transient Electromagnetic Modeling in the Laplace Domain written by and published by . This book was released on 1998 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: In modeling electromagnetic responses, Maxwell's equations in the frequency domain are popular and have been widely used (Nabighian, 1994; Newman and Alumbaugh, 1995; Smith, 1996, to list a few). Recently, electromagnetic modeling in the time domain using the finite difference (FDTD) method (Wang and Hohmann, 1993) has also been used to study transient electromagnetic interactions in the conductive medium. This paper presents a new technique to compute the electromagnetic response of three-dimensional (3-D) structures. The proposed new method is based on transforming Maxwell's equations to the Laplace domain. For each discrete Laplace variable, Maxwell's equations are discretized in 3-D using the staggered grid and the finite difference method (FDM). The resulting system of equations is then solved for the fields using the incomplete Cholesky conjugate gradient (ICCG) method. The new method is particularly effective in saving computer memory since all the operations are carried out in real numbers. For the same reason, the computing speed is faster than frequency domain modeling. The proposed approach can be an extremely useful tool in developing an inversion algorithm using the time domain data.
Download or read book Full Seismic Waveform Modelling and Inversion written by Andreas Fichtner and published by Springer Science & Business Media. This book was released on 2010-11-16 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent progress in numerical methods and computer science allows us today to simulate the propagation of seismic waves through realistically heterogeneous Earth models with unprecedented accuracy. Full waveform tomography is a tomographic technique that takes advantage of numerical solutions of the elastic wave equation. The accuracy of the numerical solutions and the exploitation of complete waveform information result in tomographic images that are both more realistic and better resolved. This book develops and describes state of the art methodologies covering all aspects of full waveform tomography including methods for the numerical solution of the elastic wave equation, the adjoint method, the design of objective functionals and optimisation schemes. It provides a variety of case studies on all scales from local to global based on a large number of examples involving real data. It is a comprehensive reference on full waveform tomography for advanced students, researchers and professionals.
