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 Multigrid Finite Element Methods for Electromagnetic Field Modeling written by Yu Zhu and published by John Wiley & Sons. This book was released on 2006-03-10 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the first comprehensive monograph that features state-of-the-art multigrid methods for enhancing the modeling versatility, numerical robustness, and computational efficiency of one of the most popular classes of numerical electromagnetic field modeling methods: the method of finite elements. The focus of the publication is the development of robust preconditioners for the iterative solution of electromagnetic field boundary value problems (BVPs) discretized by means of finite methods. Specifically, the authors set forth their own successful attempts to utilize concepts from multigrid and multilevel methods for the effective preconditioning of matrices resulting from the approximation of electromagnetic BVPs using finite methods. Following the authors' careful explanations and step-by-step instruction, readers can duplicate the authors' results and take advantage of today's state-of-the-art multigrid/multilevel preconditioners for finite element-based iterative electromagnetic field solvers. Among the highlights of coverage are: * Application of multigrid, multilevel, and hybrid multigrid/multilevel preconditioners to electromagnetic scattering and radiation problems * Broadband, robust numerical modeling of passive microwave components and circuits * Robust, finite element-based modal analysis of electromagnetic waveguides and cavities * Application of Krylov subspace-based methodologies for reduced-order macromodeling of electromagnetic devices and systems * Finite element modeling of electromagnetic waves in periodic structures The authors provide more than thirty detailed algorithms alongside pseudo-codes to assist readers with practical computer implementation. In addition, each chapter includes an applications section with helpful numerical examples that validate the authors' methodologies and demonstrate their computational efficiency and robustness. This groundbreaking book, with its coverage of an exciting new enabling computer-aided design technology, is an essential reference for computer programmers, designers, and engineers, as well as graduate students in engineering and applied physics.
Download or read book Finite Element and Finite Difference Methods in Electromagnetic Scattering written by M.A. Morgan and published by Elsevier. This book was released on 2013-10-22 with total page 398 pages. Available in PDF, EPUB and Kindle. Book excerpt: This second volume in the Progress in Electromagnetic Research series examines recent advances in computational electromagnetics, with emphasis on scattering, as brought about by new formulations and algorithms which use finite element or finite difference techniques. Containing contributions by some of the world's leading experts, the papers thoroughly review and analyze this rapidly evolving area of computational electromagnetics. Covering topics ranging from the new finite-element based formulation for representing time-harmonic vector fields in 3-D inhomogeneous media using two coupled scalar potentials, to the consideration of conforming boundary elements and leap-frog time-marching in transient field problems involving corners and wedges in two and three dimensions, the volume will provide an indispensable reference source for practitioners and students of computational electromagnetics.
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 Geophysical Inversion written by J. Bee Bednar and published by SIAM. This book was released on 1992-01-01 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: This collection of papers on geophysical inversion contains research and survey articles on where the field has been and where it's going, and what is practical and what is not. Topics covered include seismic tomography, migration and inverse scattering.
Download or read book Electromagnetic Modeling by Finite Element Methods written by João Pedro A. Bastos and published by CRC Press. This book was released on 2003-04-01 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt: Unlike any other source in the field, this valuable reference clearly examines key aspects of the finite element method (FEM) for electromagnetic analysis of low-frequency electrical devices. The authors examine phenomena such as nonlinearity, mechanical force, electrical circuit coupling, vibration, heat, and movement for applications in the elect
Download or read book A Parallel Goal oriented Adaptive Finite Element Method for 2 5D Electromagnetic Modeling written by Kerry Key and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a parallel goal-oriented adaptive finite element algorithm that can be used to rapidly compute highly accurate solutions for 2.5D controlled-source electromagnetic (CSEM) and 2D magnetotelluric (MT) modeling problems. We employ unstructured triangular grids to permit efficient discretization of complex modeling domains such as those containing topography, dipping layers and multiple scale structures. Iterative mesh refinement is guided by a goal-oriented error estimator based on a form of dual residual weighting, which is carried out using hierarchical basis computations. Our formulation of the error estimator considers the relative error in the strike aligned fields and their spatial gradients, and therefore results in a more efficient use of mesh vertices than previous error estimators based on absolute field errors. This algorithm is parallelized over frequencies, transmitters, receivers and wave-numbers, where adaptive refinement can be performed in parallel on subsets of these parameters while nearby parameters are able to share the refined grid, thus enabling our algorithm to achieve accurate solutions in run-times of seconds to tens of seconds for realistic models and data parameters when run on cluster computers containing about a thousand processors. Application of this new algorithm to a complex model that includes strong seafloor topography variations and multiple thin stacked reservoirs demonstrates the performance and scalability on a large cluster computer.
Download or read book Advances in Time Domain Computational Electromagnetic Methods written by Qiang Ren and published by John Wiley & Sons. This book was released on 2022-11-15 with total page 724 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Time-Domain Computational Electromagnetic Methods Discover state-of-the-art time domain electromagnetic modeling and simulation algorithms Advances in Time-Domain Computational Electromagnetic Methods delivers a thorough exploration of recent developments in time domain computational methods for solving complex electromagnetic problems. The book discusses the main time domain computational electromagnetics techniques, including finite-difference time domain (FDTD), finite-element time domain (FETD), discontinuous Galerkin time domain (DGTD), time domain integral equation (TDIE), and other methods in electromagnetic, multiphysics modeling and simulation, and antenna designs. The book bridges the gap between academic research and real engineering applications by comprehensively surveying the full picture of current state-of-the-art time domain electromagnetic simulation techniques. Among other topics, it offers readers discussions of automatic load balancing schemes for DG-FETD/SETD methods and convolution quadrature time domain integral equation methods for electromagnetic scattering. Advances in Time-Domain Computational Electromagnetic Methods also includes: Introductions to cylindrical, spherical, and symplectic FDTD, as well as FDTD for metasurfaces with GSTC and FDTD for nonlinear metasurfaces Explorations of FETD for dispersive and nonlinear media and SETD-DDM for periodic/ quasi-periodic arrays Discussions of TDIE, including explicit marching-on-in-time solvers for second-kind time domain integral equations, TD-SIE DDM, and convolution quadrature time domain integral equation methods for electromagnetic scattering Treatments of deep learning, including time domain electromagnetic forward and inverse modeling using a differentiable programming platform Ideal for undergraduate and graduate students studying the design and development of various kinds of communication systems, as well as professionals working in these fields, Advances in Time-Domain Computational Electromagnetic Methods is also an invaluable resource for those taking advanced graduate courses in computational electromagnetic methods and simulation techniques.
Download or read book The Finite Element Method Set written by O. C. Zienkiewicz and published by Elsevier. This book was released on 2005-11-25 with total page 1863 pages. Available in PDF, EPUB and Kindle. Book excerpt: The sixth editions of these seminal books deliver the most up to date and comprehensive reference yet on the finite element method for all engineers and mathematicians. Renowned for their scope, range and authority, the new editions have been significantly developed in terms of both contents and scope. Each book is now complete in its own right and provides self-contained reference; used together they provide a formidable resource covering the theory and the application of the universally used FEM. Written by the leading professors in their fields, the three books cover the basis of the method, its application to solid mechanics and to fluid dynamics.* This is THE classic finite element method set, by two the subject's leading authors * FEM is a constantly developing subject, and any professional or student of engineering involved in understanding the computational modelling of physical systems will inevitably use the techniques in these books * Fully up-to-date; ideal for teaching and reference
Download or read book Occam2 written by Catherine DeGroot-Hedlin and published by . This book was released on 1991 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Geophysical Data Analysis Understanding Inverse Problem Theory and Practice written by Max A. Meju and published by SEG Books. This book was released on 1994 with total page 305 pages. Available in PDF, EPUB and Kindle. Book excerpt: This publication is designed to provide a practical understanding of methods of parameter estimation and uncertainty analysis. The practical problems covered range from simple processing of time- and space-series data to inversion of potential field, seismic, electrical, and electromagnetic data. The various formulations are reconciled with field data in the numerous examples provided in the book; well-documented computer programmes are also given to show how easy it is to implement inversion algorithms.
Download or read book Analysis and Open source Implementation of Finite Element Modeling Techniques for Controlled source Electromagnetics written by Raphael Rochlitz and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Magnetotelluric Inverse Problem written by Ashley E. Medin and published by . This book was released on 2008 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: The nonlinear inverse problem of electromagnetic induction to recover electrical conductivity is examined. As this is an ill-posed problem based on inaccurate data, there is a strong need to find the reliable features of the models of electrical conductivity. By using optimization theory for an all-at-once approach to inverting frequency-domain electromagnetic data, we attempt to make conclusions about Earth structure under assumptions of one-dimensional and two-dimensional structure. The forward modeling equations are constraints in an optimization problem solving for the fields and the conductivity simultaneously. The computational framework easily allows additional inequality constraints to be imposed. Under the one-dimensional assumption, we develop the optimization approach for use on the magnetotelluric inverse problem. After verifying its accuracy, we use our method to obtain bounds on Earth's average conductivity that all conductivity profiles must obey. There is no regularization required to solve the problem. With the emplacement of additional inequality constraints, we further narrow the bounds. We draw conclusions from a global geomagnetic depth sounding data set and compare with laboratory results, inferring temperature and water content through published Boltzmann-Arrhenius conductivity models. We take the lessons from the 1-D inverse problem and apply them to the 2-D inverse problem. The difficulty of the 2-D inverse problem requires that we first examine our ability to solve the forward problem, where the conductivity structure is known and the fields are unknown. Our forward problem is designed such that we are able to directly transfer it into the optimization approach used for the inversion. With the successful 2-D forward problem as the constraints, a one-dimensional 2-D inverse problem is stepped into a fully 2-D inverse problem for testing purposes. The computational machinery is incrementally modified to meet the challenge of the realistic two-dimensional magnetotelluric inverse problem. We then use two shallow-Earth data sets from different conductivity regimes and invert them for bounded and regularized structure.
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 Two dimensional Constrained Anisotropic Inversion of Magnetotelluric Data written by Xiaoming Chen and published by . This book was released on 2012 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 A Combined Finite Element Boundary Element Formulation for Solution of Two Dimensional Problems Via Cgfft written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-13 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: A method for the computation of electromagnetic scattering from arbitrary two-dimensional bodies is presented. The method combines the finite element and boundary element methods leading to a system for solution via the conjugate gradient Fast Fourier Transform (FFT) algorithm. Two forms of boundaries aimed at reducing the storage requirement of the boundary integral are investigated. It is shown that the boundary integral becomes convolutional when a circular enclosure is chosen, resulting in reduced storage requirement when the system is solved via the conjugate gradient FFT method. The same holds for the ogival enclosure, except that some of the boundary integrals are not convolutional and must be carefully treated to maintain O(N) memory requirement. Results for several circular and ogival structures are presented and shown to be in excellent agreement with those obtained by traditional methods. Collins, Jeffery D. and Jin, Jian-Ming and Volakis, John L. Unspecified Center...
