Dissertations / Theses: 'Electromagnetic analysi'

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Bau-Hsing, Ann. "Computer-aided electromagnetic analysis of chokes and transformers." The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu1438255468.

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Wang, Xiaochuan. "A Domain Decomposition Method for Analysis of Three-Dimensional Large-Scale Electromagnetic Compatibility Problems." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1338376950.

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Gilbert, Michael Stephen. "A Small-Perturbation Automatic-Differentiation (SPAD) Method for Evaluating Uncertainty in Computational Electromagnetics." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1354742230.

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Sundberg, Garth. "Numerical Modeling of Electromagnetic Scattering in Explosive Granular Media." PDXScholar, 2010. https://pdxscholar.library.pdx.edu/open_access_etds/865.

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Terahertz (THz) reflection and transmission spectroscopy is a promising new field with applications in imaging and illicit material detection. One particularly useful application is for the detection of improvised explosive devices (IEDs) which is a favorite weapon of global terrorists. Explosive materials have been shown to have a unique spectral signature in the THz band which can be used to identify the explosives. However, the initial measurements performed on the explosive samples do not account for the modulation of the spectral features by random scattering that will be prevalent with actual samples encountered in applications. The intent of this work is to characterize and quantify the effects of random scattering that may alter the spectral features. Specifically, the effect that a randomly rough surface and granular scattering has on the scattered THz wave (T-Rays) will be investigated and characterized using the Finite-Difference Time-Domain (FDTD) simulation method. The FDTD method is a natural choice for this work as it can handle complicated geometries (i.e., multiple scatterers, arbitrarily rough interfaces, etc.) arbitrary materials (i.e., dispersive media, etc.) and provides broadband frequency data with one simulation pass. First, the effect that the randomly rough surface of the sample explosive has on the extracted spectral signature will be studied using a Monte-Carlo analysis. Then the effect of the complex structure inside the explosive material (the granular scatterers) will be considered. Next, when the physics of the rough surface and granular scattering are understood, a robust method to extract the spectral signature from the reflected T-rays will be developed.

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Häggblad, Jon. "Boundary and Interface Conditions for Electromagnetic Wave Propagation using FDTD." Licentiate thesis, KTH, Skolan för datavetenskap och kommunikation (CSC), 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-25744.

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Simulating electromagnetic waves is of increasing importance, for example, due to the rapidly growing demand of wireless communication in the fields of antenna design, photonics and electromagnetic compatibility (EMC). Many numerical and asymptotic techniques have been developed and one of the most common is the Finite-Difference Time-Domain (FDTD) method, also known as the Yee scheme. This centered difference scheme was introduced by Yee in 1966. The success of the Yee scheme is based on its relatively high accuracy, energy conservation and superior memory efficiency from the staggered form of defining unknowns. The scheme uses a structured Cartesian grid, which is excellent for implementations on modern computer architectures. However, the structured grid results in loss of accuracy due to general geometry of boundaries and material interfaces. A natural challenge is thus to keep the overall structure of Yee scheme while modifying the coefficients in the algorithm near boundaries and interfaces in order to improve the overall accuracy. Initial results in this direction have been presented by Engquist, Gustafsson, Tornberg and Wahlund in a series of papers. Our contributions are new formulations and extensions to higher dimensions. These new formulations give improved stability properties, suitable for longer simulation times. The development of the algorithmsis supported by rigorous stability analysis. We also tackle the problem of controlling the divergence free property of the solution—which is of extra importance in three dimensions—and present results of a number of numerical tests.
QC 20101101

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Kimn, Edward Sun. "A parametric finite element analysis study of a lab-scale electromagnetic launcher." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39498.

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The purpose of the study is to better understand the factors that affect melt-wear in the armature-to-rail contact interface of an electromagnetic launcher (EML). In order to investigate the factors, the study uses finite element analysis (FEA) to vary parameters of a lab-scale EML at the Georgia Institute of Technology. FEA is used due to the complex nature of the system, which includes the geometry and various engineering aspects that the EML incorporates. The study focuses on an uncoupled analysis of the structural, electromagnetic (EMAG), thermal, and modal aspects. The reason for the uncoupled analysis was because the system was complex and there were computational limits. Also, by uncoupling the analysis fields, the way the parameters affected melt-wear could be viewed separately. The study varied the geometry of the armature, the stiffness of the rail system (compliance layer), and the material of the armature. The structural analysis was for the initial contact of the rail to the armature and found the von Mises stresses, contact area, and contact pressure. The EMAG analysis found the Lorentz forces in the system based on a current curve used in the lab-scale EML. The thermal analysis consisted of friction heating and Joule heating. The modal analysis was for the unstressed and pre-stressed armature. Based on the study conducted, it was found that aluminum would provide the best speeds due to its lighter mass, but lacked in the thermal resistance area. Tungsten provided the better thermal resistance, but lacked in the potential speed due to its heavier mass.

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Stevenson, Adrian Carl. "Electromagnetic biosensors." Thesis, University of Cambridge, 1995. https://www.repository.cam.ac.uk/handle/1810/252090.

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Germany, Garrett Ross. "ANALYSIS OF ELECTROMAGNETIC LAUNCHER DESIGN AND MODELING." DigitalCommons@CalPoly, 2016. https://digitalcommons.calpoly.edu/theses/1563.

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This thesis derives working expressions from electromagnetic physical laws to gain a deeper understanding of the nature of railguns. The expressions are refined for ease of use and then compared to electromagnetic simulators that solve complex equations that arise from different rail geometry. Further simplifications lead to an expression for the final velocity of the projectile and showcase the importance of the system resistance to projectile flux gain ratio. A Simulink simulation then incorporates the resulting non-linear differential equations and approximates the projectile velocity over time based on physical dimensions and material properties. Some equations derived can be found in literature regarding the subject but often lack explanation. This work is intended to provide a thorough derivation of all the relative constituent relations between the critical characteristics of the gun such as the strength of the forces acting on the rail and projectile, rail current, and initial velocity of the projectile. This makes it easier to identify what influences acceleration of the projectile, how much bracing each rail needs, how much initial velocity to give the projectile, etc. Design options discussed besides the standard design include the augmented rail system, a magnetic shell design, and a “wrap around” design. The tradeoffs encountered in each design are discussed in length. Due to the lack of a sufficient power source during testing the projectile was unable to travel down the length of the rails due to metal binding, insufficient pulse duration, and too much circuit resistance. It was found that using copper tungsten for the rails ensures that the rails can withstand the arcing inflicted by the kilo-Ampere current along the rails very well compared to other materials. Also, the copper in the tungsten alloy ensures high conductivity while the tungsten provides structural integrity to the rails during arcing between them and the projectile. Frequency response of conductive projectiles is characterized and improvements such as laminated projectiles are suggested as solutions to mitigate eddy currents induced in the projectile and improve performance.

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Ranlöf, Martin. "Electromagnetic Analysis of Hydroelectric Generators." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-146629.

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Hydropower maintains its position as the most important source of renewable electric energy in the world. The efficiency of large hydropower plants is unsurpassed, and after more than hundred years of development, the technology is mature and highly reliable. While new hydro resources are currently being developed in Asia and South America, most European countries go through a phase of intense refurbishment and upgrading of existing plants. Challenges faced by the hydropower industry include a knowledge transfer to new generations and the adaptation of unit designs to meet new operational requirements. As with all branches of engineering, the use of computerized design tools has revolutionized the art of hydropower plant design and the analysis of its performance. In the present work, modern tools like coupled field-circuit models and semi-analytic permeance models are used to address different aspects of electromagnetic analysis of generators in large hydropower plants. The results include the presentation of a mathematical model that uses concepts from rotating field theory to determine the air-gap flux density waveform in a hydroelectric generator. The model was succesfully used to evaluate armature voltage harmonics and damper bar currents at no-load and load conditions. A second study is concerned with the importance of losses due to rotational fields in core loss calculations. It is found that dynamic and rotational effects typically increase the total core loss estimates with about 28% in large hydroelectric generators. In a third study, linear models for the calculation of salient pole shoe form factors at an arbitrary level of magnetic loading are presented. The effect of the damper winding configuration on the damping capability of salient-pole generators is then evaluated in a separate study. The predicted impact of the coupling between damper cages on adjacent poles on the damping torque production is verified in a set of experiments.

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Zafaruddin, Mohammed. "Finite Element Analysis of EMI in a Multi-Conductor Connector." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1354861237.

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Kang, Sangwoo. "Direct sampling method in inverse electromagnetic scattering problem." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS417/document.

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Le problème de l'imagerie non itérative dans le cadre de la diffraction électromagnétique inverse utilisant la méthode d'échantillonnage direct (DSM) est considéré. Grâce à une combinaison de l'expression asymptotique du champ proche ou du champ lointain diffracté et de l'hypothèse de petits obstacles, les expressions analytiques de la fonction d'indicateur DSM sont présentées dans diverses configurations telles que des configurations 2D/3D, mono-/multi-configurations statiques, à vue limitée/complète et fréquence unique/ diversité en fréquence. Une fois l'expression analytique obtenue, sa structure est analysée et des améliorations proposées. Notre approche est validée à l’aide de données de simulation, et d’expériences le cas échéant. Premièrement, la structure mathématique du DSM à fréquence fixe en 2D dans divers problèmes de diffusion est établie, permettant une analyse théorique de son efficacité et de ses limites. Pour surmonter les limitations connues, une méthode alternative d'échantillonnage direct (DSMA) est proposée. Puis le cas multi-fréquence est investigué en introduisant et en analysant le DSM multi-fréquence (MDSM) et le DSMA multi-fréquence (MDSMA). Enfin, notre approche est étendue aux problèmes de diffraction électromagnétique inverse 3D pour lesquels le choix de la polarisation du dipôle de test est un paramètre clé. De par notre approche analytique, ce choix peut être effectué sur la base de la polarisation du champ incident
The non-iterative imaging problem within the inverse electromagnetic scattering framework using the direct sampling method (DSM) is considered. Thanks to the combination of the asymptotic expression of the scattered near-field or far-field and of the small obstacle hypothesis the analytical expressions of the DSM indicator function are presented in various configurations such as 2D/3D configurations and/or mono-/multi-static configurations and/or limited-/full-view case and/or mono-/multi-frequency case. Once the analytical expression obtained, its structure is analyzed and improvements proposed. Our approach is validated using synthetic data and experimental ones when available. First, the mathematical structure of DSM at a fixed frequency in 2D various scattering problems is established allowing a theoretical analysis of its efficiency and limitations. To overcome the known limitations an alternative direct sampling method (DSMA) is proposed. Next, the multi-frequency case is investigated by introducing and analyzing the multi-frequency DSM (MDSM) and the multi-frequency DSMA (MDSMA).Finally, our approach is extended to 3D inverse electromagnetic scattering problems for which the choice of the polarization of the test dipole is a key parameter. Thanks to our analytical analysis it can be made based on the polarization of the incident field

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Hue, Yik-Kiong. "Analysis of electromagnetic well-logging tools." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1143053776.

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Caliskan, Fatma. "Electromagnetic Analysis of Planar Layered Structures." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5116.

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ELECTROMAGNETIC ANALYSIS OF PLANAR LAYERED STRUCTURES Fatma Caliskan 169 pages Directed by Dr. Andrew F. Peterson The electrical design of microelectronic devices and their packaging is complicated because of non-ideal attributes of the actual circuit realization. Electromagnetic modeling offers the possibility of accurately predicting the electrical performance of devices and reducing the cost associated with the design process. The proposed research concerns extensions of electromagnetic modeling techniques and their application to microelectronic package design. The method of moments (MoM) is utilized as a technique in modeling and analyzing these designs. Recently, an alternate approach called the locally corrected Nystrm method (LCN) has been applied to solve integral equations in electromagnetics. Recent research suggests that the LCN is well-suited for higher-order implementations and does not require cell-to-cell current continuity in the underlying representation. Thus it may offer advantages over the MoM, especially for problems involving complex 3-D structures. If cell-to-cell continuity is not required, nonconforming meshes may offer simpler geometrical modeling. In this proposal, we consider applying the above techniques to problems in package designs, which often involve multilayer structures, solid or perforated ground planes, embedded passive devices such as capacitors and spiral inductors, and interconnects in horizontal or vertical directions. Several examples will be used to illustrate the modeling.

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Refig, Andre. "Computational electromagnetic analysis of periodic structures." Thesis, Imperial College London, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520979.

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Calay, Rajnish Kaur. "Electromagnetic heating processes : analysis and simulations." Thesis, Cranfield University, 1994. http://dspace.lib.cranfield.ac.uk/handle/1826/9846.

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Electromagnetic heating (EMH) processes are being increasingly used in the industrial and domestic sectors, yet they receive relatively little attention in the thermal engineering domain. Time-temperature characteristics in EMH are qualitatively different from those in conventional heating techniques due to the additional parameters (viz dielectric properties of the material, size and shape of the product and process frequency). From a unified theory perspective, a multi-purpose model has been developed in order to obtain the heating characteristics for an arbitrary processing situation. Theoretical analyses of various EMH processes in materials of various regular geometries and a range of physical properties have been undertaken. Despite the wide spread usage of microwave energy in the food engineering sector. few understand microwaves and their interactions with foods. Much of the published research is largely focussed from the view point of an electrical engineer and aimed at the oven designer. However, trial-and-error methods are usually employed when developing microwavable food products and when using microwave ovens. The presented thesis is focussed from the view-point of the thermal engineer and aimed primarily at food developers and end users. The multi-purpose model was then modified specifically for simulating the heating of food materials in a microwave oven. The validity of the commonly made assumptions was investigated; in particular the variation of dielectriC properties during the heating processes and their likely influence on the model's predictions. Experimental data available in the literature were compiled and analysed to form a set of equations for predicting the dielectric properties of various food materials. Also available correlations for thermal properties were evaluated for a selected set of experimental data of different food materials. Analyses were undertaken to demonstrate and evaluate the effects of various parameters on the heating characteristics of different food materials commonly heated/cooked in microwave ovens. A qualitative comparison of model predictions and experimental measurements is provided to validate the physical basis of the model. Findings from the model lead to a better understanding of the interactions between foods and microwaves. [...cont.]

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Eschweiler, Zachary Taylor. "Superparamagnetic Nanoparticle TechnologyAn Analysis of Water, Water-treatment, Health-risks of Contaminated Water, and a Proposed Solution." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1497012927923017.

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Pan, Weifeng. "EMI failure analysis techniques and noise prediction for trace crossing split planes." Diss., Rolla, Mo. : Missouri University of Science and Technology, 2009. http://scholarsmine.mst.edu/thesis/pdf/Pan_09007dcc80663d0c.pdf.

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Thesis (Ph. D.)--Missouri University of Science and Technology, 2009.
Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed May 27, 2009) Includes bibliographical references.

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DeWitt, Brian Thomas. "Analysis and measurement of electromagnetic scattering by pyrimidal and wedge absorbers /." The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487265143144813.

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Lundengård, Karl. "Generalized Vandermonde matrices and determinants in electromagnetic compatibility." Licentiate thesis, Mälardalens högskola, Utbildningsvetenskap och Matematik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-34864.

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Matrices whose rows (or columns) consists of monomials of sequential powers are called Vandermonde matrices and can be used to describe several useful concepts and have properties that can be helpful for solving many kinds of problems. In this thesis we will discuss this matrix and some of its properties as well as a generalization of it and how it can be applied to curve fitting discharge current for the purpose of ensuring electromagnetic compatibility. In the first chapter the basic theory for later chapters is introduced. This includes the Vandermonde matrix and some of its properties, history, applications and generalizations, interpolation and regression problems, optimal experiment design and modelling of electrostatic discharge currents with the purpose to ensure electromagnetic compatibility. The second chapter focuses on finding the extreme points for the determinant for the Vandermonde matrix on various surfaces including spheres, ellipsoids, cylinders and tori. The extreme points are analysed in three dimensions or more. The third chapter discusses fitting a particular model called the p-peaked Analytically Extended Function (AEF) to data taken either from a standard for electromagnetic compatibility or experimental measurements. More specifically the AEF will be fitted to discharge currents from the IEC 62305-1 and IEC 61000-4-2 standards for lightning protection and electrostatic discharge immunity as well as some experimentally measured data of similar phenomena.

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Zhang, Xu. "Implicitly-coupled electromechanical and electromagnetic transient analysis." Thesis, Illinois Institute of Technology, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3664035.

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The operation of an electrical power system involves continuous electromechanical and electromagnetic interaction of energy among the system components. Under normal operation, the system behavior could be represented by voltage and current phasors in the frequency domain. However, the system may not work on the fundamental frequency following some fast transients (loss of generator, switching event, system disturbance and etc.), at this time we need specific tools to investigate the dynamic scenario.

Transient stability (TS) simulator, also referred to as electromechanical transient simulator, running at time steps on the order of milliseconds and only capable of capturing the fundamental frequency transient, is used for the analysis of large-scale networks. On the other hand the electromagnetic transient (EMT) simulator running at time steps on the order of microseconds, with detailed equipment modeling is capable of analyzing transients over a wider frequency spectrum; however, it is computationally onerous, so it is typically restricted to the analysis of small networks.

An electromechanical-electromagnetic transient simulator is the combination of a TS simulator and an EMT simulator, inheriting the merits of both programs The basic idea of an electromechanical-electromagnetic simulator is to decompose the power system into two broad categories: a large connected TS network (main network) and smaller EMT network (detailed subsystem). The main network is running on TS simulator while the detailed subsystem is running on the EMT simulator. The implicitly-coupled electromechanical and electromagnetic simulator has TS and EMT simulators coupled at the equation solution level, which could ensure the consistence of the solution between TS and EMT simulation.

Instead of using fundamental frequency equivalent model of the main network in EMT simulation of implicitly-coupled electromechanical and electromagnetic simulator, a frequency dependent network equivalent (FDNE) model is utilized to preserve the non-fundamental frequency fast transient response of the main network.

Along with the implementation of FDNE model, this research work also propose a new TS simulator that is capable of running three-phase transient stability simulation under fundamental and non-fundamental frequency simultaneously. Furthermore the performance of implicitly-coupled electromechanical-electromagnetic transient simulator could be improved with the implementation of this new TS simulator.

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Guo, Yunchuan. "Analysis and design of novel electromagnetic metamaterials." Thesis, Loughborough University, 2006. https://dspace.lboro.ac.uk/2134/7864.

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This thesis introduces efficient numerical techniques for the analysis of novel electromagnetic metamaterials. The modelling is based on a Method of Moments modal analysis in conjunction with an interpolation scheme, which significantly accelerates the computations. Triangular basis functions are used that allow for modelling of arbitrary shaped metallic elements. Unlike the conventional methods, impedance interpolation is applied to derive the dispersion characteristics of planar periodic structures. With these techniques, the plane wave and the surface wave responses of fractal structures have been studied by means of transmission coefficients and dispersion diagrams. The multiband properties and the compactness of the proposed structures are presented. Based on this method, novel planar left-handed metamaterials are also proposed. Verifications of the left-handedness are presented by means of full wave simulation of finite planar arrays using commercial software and lab measurement. The structures are simple, readily scalable to higher frequencies and compatible with low-cost fabrication techniques.

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Newman, Peter. "Dynamic analysis of an electromagnetic shutter system /." Online version of thesis, 1992. http://hdl.handle.net/1850/10787.

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Lu, Chuan. "Generalized finite element method for electromagnetic analysis." Diss., Connect to online resource - MSU authorized users, 2008.

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Thesis (Ph. D.)--Michigan State University. Electrical and Computer Engineering, 2008.
Title from PDF t.p. (viewed on Apr. 8, 2009) Includes bibliographical references (p. 148-153). Also issued in print.

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Khan, Zulfiqar A. "EMI/EMC analysis of electronic systems subject to near zone illuminations." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1196207323.

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Hagdahl, Stefan. "Hybrid Methods for Computational Electromagnetics in Frequency Domain." Doctoral thesis, Stockholm : Numerisk analys och datalogi (NADA) ; Tekniska högsk, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-400.

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Foo, Seng-Lee. "Analysis of electromagnetic fields in loaded TEM cells." Thesis, University of Ottawa (Canada), 1988. http://hdl.handle.net/10393/5170.

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Aghajafari, Ramin. "Transient electromagnetic scattering analysis of homogeneous material bodies /." [Lautertal] : Stephan, 2006. http://deposit.d-nb.de/cgi-bin/dokserv?id=2878273&prov=M&dok_var=1&dok_ext=htm.

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Pinchuk, Amy Ruth. "Spectrally correct finite element analysis of electromagnetic fields." Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=75780.

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Direct solution for three dimensional electric or magnetic field vectors throughout the frequency spectrum is accomplished by a finite element formulation which includes displacement and conduction currents, and requires no special treatment for material interfaces. Analysis of bus bar and Bath cube eddy current problems demonstrate the capabilities of the method.
Spurious components in solutions to vector field problems are shown to corrupt deterministic solutions. These corruptions are identifiable with spurious modes familiar to high frequency modal analysis. Spectrally correct mixed order finite elements are demonstrated to retrieve accuracy in deterministic analyses.
The formulation may be limited by computer round-off at matrix assembly which affects the solenoidality of vector fields. Furthermore, extreme values encountered in low frequency eddy current analysis lead to ill conditioning and unreliable solutions. These numerical instabilities are overcome by parametric adjustment of permittivities. Error estimates are established to monitor inaccuracies introduced by permittivity adjustment.

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Looe, Hui Mun. "Electromagnetic modelling and analysis of electrical engineering systems." Thesis, University of Liverpool, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400238.

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Sturgess, J. P. "Finite element electromagnetic analysis of generator transient performance." Thesis, Imperial College London, 1988. http://hdl.handle.net/10044/1/47264.

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Leibman, Stephen Gerald. "A generalized precorrected-FFT method for electromagnetic analysis." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/42456.

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Thesis (S.M.)--Massachusetts Institute of Technology, Computation for Design and Optimization Program, 2008.
Includes bibliographical references (p. 117-119).
Boundary Element Methods (BEM) can be ideal approaches for simulating the behavior of physical systems in which the volumes have homogeneous properties. These, especially the so-called "fast" or "accelerated" BEM approaches often have significant computational advantages over other well-known methods which solve partial differential equations on a volume domain. However, the implementation of techniques used to accelerate BEM approaches often comes at a loss of some generality, reducing their applicability to many problems and preventing engineers and researchers from easily building on a common, popular base of code. In this thesis we create a BEM solver which uses the Pre-Corrected FFT technique for accelerating computation, and uses a novel approach which allows users to provide arbitrary basis functions. We demonstrate its utility for both electrostatic and full-wave electromagnetic problems in volumes with homogeneous isotropic permittivity, bounded by arbitrarily complex surface geometries. The code is shown to have performance characteristics similar to the best known approaches for these problems. It also provides an increased level of generality, and is designed in such a way that should allow it to easily be extended by other researchers.
by Stephen Gerald Leibman.
S.M.

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Craddock, I. J. "Enhanced numerical techniques for time domain electromagnetic analysis." Thesis, University of Bristol, 1995. http://hdl.handle.net/1983/9ac15a09-f4cd-4971-beb4-80f038c0f561.

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Buzzi, Aurora. "DEMETER Satellite data analysis of seismo-electromagnetic signals." Orléans, 2007. http://www.theses.fr/2007ORLE2014.

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Zhao, Zihao. "Far Field Electromagnetic Side Channel Analysis of AES." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-281343.

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Side-Channel Attacks (SCAs) have become a realistic threat to implementations of cryptographic algorithms. By utilizing the unintentionally leaked side-channel information during the execution of a cryptographic algorithm, it is possible to bypass the theoretical strength of the algorithm and extract its secret key. Recently, far-field electromagnetic (EM) emissions have been used in SCAs to extract keys from mixed- signal chips used in wireless communication protocols (such as Bluetooth). In such type of chips, the EM leakage is mixed with radio carrier and accidentally amplified by the antenna. Attacks exploiting such far-field EM side-channels may succeed over a much longer distance than the attacks based on near-field EM side-channels. Therefore, it is necessary to further investigate far-field EM side channels.In this thesis, we perform far-field EM side-channel attacks using two techniques: correlation and template analysis. We analyse an Arm Cortex-M4 microprocessor implementation of Advanced Encryption Standard (AES)-128 with a Bluetooth module on different distances up to 50cm. We first evaluate how the inter-chip diversity and the distance can affect the attack efficiency of template analysis. Our current results show that a template constructed using traces from one device captured at distance d can recover the secret key from 4,000 traces from the d device captured at the same distance d. However, if the distance is changed, or if traces are captured from different devices, the attack fails. This shows that it is not sufficient to build a template based on traces captured from a single device at a fixed distance. In addition, we present a pre- processing technique for allocating leakage points, which can significantly improve the attack efficiency of correlation analysis.
Side channel attacks har blivit ett realistiskt hot mot implementering av kryptografiska algoritmer. Genom att använda den oavsiktligt läckta sidokanalinformationen under exekveringen av en kryptografisk algoritm är det möjligt att kringgå algoritmens teoretiska styrka och extrahera dess hemliga nyckel. Nyligen har EM-utsläpp från fältfält använts i SCAsför att extrahera nycklar från blandade signalchips som används i trådlösa kommunikationsprotokoll (t.ex. Bluetooth). I en sådan typ av chips blandas EM-läckan med radiobäraren och förstärks av misstag av antennen. Attacker som utnyttjar sådana långtgående EM-sidokanaler kan lyckas på mycket längre avstånd än attackerna baserade på EM-sidokanaler nära fältet. Därför är det nödvändigt att ytterligare undersöka EM-sidokanalanalyser från fältet. I denna avhandling utför vi EM-sidokanalanalys med fältfält med två tekniker: korrelationsanalys och mallanalys. Vi analyserar en Arm Cortex-M4-mikroprocessorimplementering av AES med en Bluetooth-modul inbäddad på kortet på olika avstånd upp till 50 cm från den mottagande antennen. Vi utvärderar först hur mångfalden mellan chip och avståndet kan påverka attackeffektiviteten för mallanalys. Våra nuvarande resultat visar att en mall konstruerad med spår från en enhet fångad på avstånd d från den mottagande antennen kan återställa den hemliga nyckeln från 4K spår från samma enhet som fångats på samma avstånd d från den mottagande antennen. Om avståndet ändras eller om spår från en annan enhet analyseras misslyckas dock attacken. Detta visar att det inte är tillräckligt att bygga en mall baserad på spår från en enda enhet fångad på ett fast avstånd från den mottagande antennen. Dessutom presenterar vi en förbehandlingsteknik för allokering av läckagepunkter i spåren och visar att den kan förbättra attackeffektiviteten för korrelationsanalysen betydligt.

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35

Cajko, Frantisek. "Nano-Focusing of Light: Electromagnetic Analysis and Simulation." University of Akron / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1249331504.

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Čajko, František. "Nano-focusing of light electromagnetic analysis and simulation /." Akron, OH : University of Akron, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1249331504.

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Dissertation (Ph. D.)--University of Akron, Dept. of Electrical and Computer Engineering, 2009.
"August, 2009." Title from electronic dissertation title page (viewed 9/23/2009) Advisor, Igor Tsukerman; Committee members, Nathan Ida, Iqbal Husain, Ernian Pan; Department Chair, Alex De Abreu Garcia, Dmitry Golovaty; Dean of the College, George K. Haritos; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.

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Kodali, Venkateswararao. "Characterization and analysis of close lightning electromagnetic fields." [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0000724.

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Schena, Michael L. "An Electromagnetic Coupling Model for Side-Channel Analysis." DigitalCommons@USU, 2016. https://digitalcommons.usu.edu/etd/5224.

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This thesis presents an EM coupling model used to enhance power, side-channel measurements used in CPA. The Kalman filter is used to combine measurements of magnetic flux density with voltage or current traditionally used to measure power consumption. The DES encryption algorithm is used to evaluate CPA using EM coupled power measurements compared to traditional power measurements.

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Ayar, Mehmet. "Design Of An Electromagnetic Classifier For Spherical Targets." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12605983/index.pdf.

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This thesis applies an electromagnetic feature extraction technique to design electromagnetic target classifiers for conductors, dielectrics and dielectric coated conductors using their natural resonance related late-time scattered responses. Classifier databases contain scattered data at only a few aspects for each candidate target. The targets are dielectric spheres of varying sizes and refractive indices, perfectly conducting spheres varying sizes and dielectric coated conducting spheres of varying refractive indices and thickness in coating. The applied classifier design technique is suitable for real-time target classification because of the computational efficiency of feature extraction and decision making approaches. The Wigner-Ville Distribution (WD) is employed in this study in addition to the Principal Components Analysis (PCA) technique to extract target features mainly from late-time target responses. WD is applied to the back-scattered responses at different aspects. To decrease aspect dependency, feature vectors are extracted from selected late-time portions of the WD outputs that include natural resonance related information. Principal components analysis is also used to fuse the feature vectors and/or late-time target responses extracted from reference aspects of a given target into a single characteristic feature vector for each target to further reduce aspect dependency.

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Dai, Qi, and 代祺. "Efficient eigenvalue based analysis of bounded and unbounded electromagnetic fields." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/196029.

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Eigenvalue problems find important applications in engineering electromagnetics. The most studied examples are cavity resonance problems and wave guidance problems, in which the electromagnetic fields are bounded or semi-bounded. Efficient eigenvalue based analysis is developed to investigate both bounded and unbounded fields in a unified manner. Incorporating a locally-conformal finite difference technique, a modal expansion based model order reduction is proposed to elucidate complicated physics of wave-matter interaction, and the fast field approximation provides quick guidance to design and optimization problems of a variety of devices. As the key to modal expansion, modal analysis for interior spectrum needs to be carried out efficiently in large scale applications. A null-space shift algorithm and a fast cosine- and sine- transform based preconditioning scheme are proposed to greatly enhance the performance of a conventional eigensolver. To model multi-junction parallel plate waveguides, both explicit and implicit mode matching schemes are introduced, where eigenanalysis are incorporated. Both schemes intelligently conform to the geometrical characteristics, which are suitable for demonstrating interesting phenomena of zero index materials. Finally, a differential forms inspired discretization scheme is proposed for the edge element based finite element analysis of waveguide problems where the variational expressions involve transverse fields only. Differential forms provide useful insight on the discretization of complicated variational expressions.
published_or_final_version
Electrical and Electronic Engineering
Doctoral
Doctor of Philosophy

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41

Belushkin, Maxim. "Dispersion theoretical analysis of the nucleon electromagnetic form factors." [S.l.] : [s.n.], 2007. http://deposit.ddb.de/cgi-bin/dokserv?idn=984865993.

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Serefoglu, Murat Mehmet. "Electromagnetic Scattering Analysis And Design Of Sandwich Type Radomes." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610527/index.pdf.

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In this thesis work, importance of radome structures for antenna systems is emphasized. Structural and electromagnetic requirements of various types of radome structures are analyzed and specific properties are given. Electromagnetic scattering analysis of sandwich type radome seams has been done. Total antenna system far electromagnetic field expression, which is the combination of original antenna far electromagnetic field and the scattered electromagnetic field of the framework of the sandwich radome structure has been found and simulated. To enhance electromagnetic transparency of sandwich type radomes two sandwich radome design methods are proposed which are expressed as Geometrical Randomization and Tuning the Seams. Electromagnetic scattering level minimizations advanced by these design methods are presented with related simulations.

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Fair, Ruben Jeevanasan. "Analysis and design of electromagnetic moving coil vibration generators." Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/7830.

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Choi, Charles Tak Ming. "Adaptive finite element analysis of unbounded electromagnetic wave problems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ29911.pdf.

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Choi, Charles Tak Ming. "Adaptive finite element analysis of unbounded electromagnetic wave problems." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=42004.

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An adaptive finite element method is developed to solve two dimensional unbounded electromagnetic radiation and scattering problems.
Though there has been considerable research in adaption in electromagnetics, to date there have been few attempts to deal with adaptively reducing the error introduced by the boundary that artificially truncates the unbounded domain in a finite element analysis. The technique proposed here adapts on this boundary error, as well as on the usual finite element discretization error. It combines three techniques: (i) p-adaptive hierarchial triangular finite elements, (ii) wave-envelope elements and (iii) absorbing boundary conditions.
Hierarchial finite elements allow the polynomial orders of the elements to be used to control the distribution of degrees of freedom, and therefore they make p-adaption possible, i.e. adaption by varying the element orders. This is more efficient than h-adaption which requires an actual re-meshing of the finite elements.
The wave-envelope method uses a change of dependent variable to remove the wave-like qualities of the solution and thereby permits the use of very large elements, i.e. elements much larger than a wavelength, in the external domain.
An absorbing boundary condition is a boundary operator which approximately absorbs all the radiation incident on the boundary from within.
In the new method, the scattering or radiating object itself, and its immediate surroundings, are meshed with hierarchial finite elements. Outside that, a thick layer of free space is meshed with hierarchial wave-envelope elements. The layer is thick enough that when an absorbing boundary condition is imposed on its outer surface, there is very small reflection from it. Such a thick layer can be meshed with relatively few wave-envelope elements. The boundary error seen by the finite element region is then a function of how well the wave-envelope region is discretized. During the p-adaption, increasing the order of the wave-envelope elements increases their ability to model the field accurately and therefore reduces the boundary error. Moreover, this reduction in boundary error is selective: in directions of strong radiation, the error reduction is greater.
The new method is validated by comparison with exact solutions for a number of radiation and scattering problems over a range of frequencies.

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Hodgers, Philip Thomas. "Pre-processing techniques for electromagnetic & power analysis attacks." Thesis, Queen's University Belfast, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.602543.

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The research presented in this thesis has led to several new pre-processing techniques that enhance side-channel analysis of near-field electromagnetic (EM) and power analysis waveforms. Three new power spectral density analysis techniques have been introduced, the sliding window, the overlapping window and the variable window methods. These approaches pre-process the information in the time-shift invariant frequency domain, overcoming issues of misalignment due to acquisition error or random insertion type countermeasures. A new pattern analysis technique, that models the charge and decay profiles of AES power consumption traces, has been shown to defeat a random clocking countermeasure. The individual rounds of the algorithm are identified, enabling the targeted round to be extracted from each trace. A further optimisation is demonstrated using a round separation metric to identify prior rounds where a sufficient power consumption decay has occurred, resulting in a further reduction in the number of traces required. The attack therefore overcomes the effects of the temporal misalignment and round amplitude variation caused by the random clocking countermeasure. The novel application of a DSP implementation of a phase-sensitive detector circuit has enabled the pre-processing of side-channel information to enhance the round patterns of an AES algorithm for the purposes of re-alignment and cryptographic signature extraction. The identification of locations on a device where the encryption signature is more readily visible, leads to a more efficient targeting of attacks in a side-channel cartography attack.

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Gustafsson, Stefan. "Electromagnetic dispersion modeling and analysis for HVDC power cables." Licentiate thesis, Linnéuniversitetet, Institutionen för datavetenskap, fysik och matematik, DFM, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-32525.

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Derivation of an electromagnetic model, regarding the wave propagation in a very long (10 km or more) High Voltage Direct Current (HVDC) power cable, is the central part of this thesis. With an existing “perfect” electromagnetic model there are potentially a wide range of applications.The electromagnetic model is focused on frequencies between 0 and 100 kHz since higher frequencies essentially will be attenuated. An exact dispersion relation is formulated and the propagation constant is computed numerically. The dominating mode is the first Transversal Magnetic (TM) mode of order zero, denoted TM01, which is also referred to as the quasi-TEM mode. A comparison is made with the second propagating TM mode of order zero denoted TM02. The electromagnetic model is verified against real time data from Time Domain Reflection (TDR) measurements on a HVDC power cable. A mismatch calibration procedure is performed due to matching difficulties between the TDR measurement equipment and the power cable regarding the single-mode transmission line model.An example of power cable length measurements is addressed, which reveals that with a “perfect” model the length of an 80 km long power cable could be estimated to an accuracy of a few centimeters. With the present model the accuracy can be estimated to approximately 100 m.In order to understand the low-frequency wave propagation characteristics, an exact asymptotic analysis is performed. It is shown that the behavior of the propagation constant is governed by a square root of the complex frequency in the lowfrequency domain. This thesis also focuses on an analysis regarding the sensitivity of the propagation constant with respect to some of the electric parameters in the model. Variables of interest when performing the parameter sensitivity study are the real relative permittivityand the conductivity.

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McKenzie, Wilfred. "Characterisation of microwave passive networks based on electromagnetic analysis." Thesis, University of Leeds, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278080.

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FALCONI, MARTA TECLA. "Remote sensing and electromagnetic modeling applied to weather and forward scatter radar." Doctoral thesis, 2018. http://hdl.handle.net/11573/1080160.

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This dissertation deals with electromagnetic modelling and data analysis, related to radar remote sensing and applied to forward scatter and meteorological polarimetric systems. After an overview of radar fundamentals to introduce the general terminology and concepts, results are presented at the end of each chapter. In this respect, a generalized electromagnetic model is first presented in order to predict the response of forward scatter radars (FSRs) for airtarget surveillance applications in both near-field and far-field regions. The model is discussed for increasing levels of complexity: a simplified near-field model, a near-field receiver model and a near-field receiver and transmitter model. FSR results have been evaluated in terms of the effects of different target electrical sizes and detection distances on the received signal, as well as the impact of the trajectory of the moving objects and compared with a customized implementation of a full-wave numerical tool. Secondly, a new data processing methodology, based on the statistical analysis of ground-clutter echoes and aimed at investigating the monitoring of the weather radar relative calibration, is presented. A preliminary study for an improvement of the ground-clutter calibration technique is formulated using as a permanent scatter analysis (PSA) and applied to real radar scenarios. The weather radar relative calibration has been applied to a dataset collected by a C-band weather radar in southern Italy and an evaluation with statistical score indexes has drawn through the comparison with a deterministic clutter map. The PSA technique has been proposed using a big metallic roof with a periodic mesh grid structure and having a hemispherical shape in the near-field of a polarimetric C-band radar and evaluated also with an ad-hoc numerical implementation of a full-wave solution. Finally, a radar-based snowfall intensity retrieval is investigated at centimeter and millimeter wavelengths (i.e., at X, Ka and W band) using a high-quality database of collocated ground-based precipitation measurements and radar multi-frequency observations. Coefficients for the multifrequency radar snowfall intensity retrieval are empirically derived using multivariate regression techniques and their interpretation is carried out by particle scattering simulations with soft-ice spheroids. For each topic, conclusions are proposed to highlight the goals of the whole work and pave the way for future studies.

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NTIBARIKURE, LAURENT. "Contributions to the Art of Finite Element Analysis in Electromagnetics." Doctoral thesis, 2014. http://hdl.handle.net/2158/843133.

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The finite element method is a powerful method for the approximate solution of boundary value problems governed by partial differential equations. A really first application to structural engineering problems, dating 1943, is attributed to R. Courant. Since then, there has been a lot of successful tentatives to apply the method to other fields. In particular, Silvester showed in 1969 that waveguide modes could be easily computed with the method. His work started a long path for finite elements in electromagnetics, with multiple assessments of the method with real-world problems and gradually improving the efficiency of the algorithms. Nowadays, finite elements in computational electromagnetics has become an invaluable part in radio frequency and microwave application designs, and many packages are widely available to perform these tasks. However, there remain a lot of problems to be solved. In this dissertation, we have inquired in two of these. The first, the efficient solution of large problems which may not be solvable on a single modern computer. Domain decomposition methods have been thus investigated, these allowing to solve smaller parts of a large problem and to achieve the whole solution upon proper interconnection. Two types of domain decomposition methods have been analyzed, leading to the construction of algorithms for solving large electromagnetic problems at a nearly linear complexity. The other, the accurate solution of electromagnetic problems in which some materials behave nonlinearly, that is their properties vary depending on the intensity of the fields they imbue. Almost all materials behave nonlinearly and their effect is just a matter of fields intensities and accuracy requirements. In many microwave applications, the nonlinear effects, necessary for information processing and control, are still limited to lumped devices for their highly developed models. Accurate modeling of bulk or films of nonlinear materials may open the way to a new variety of controllable materials in flexible, reconfigurable, electromagnetic devices. A finite element package has been implemented to perform several tests here documented.

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Dissertations / Theses on the topic 'Electromagnetic analysi'

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