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Dissertations / Theses on the topic 'Electromagnetism'

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Author: Grafiati

Published: 4 June 2021

Last updated: 30 July 2024

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1

Fouda, Ahmed Elsayed. "Electromagnetic Time-Reversal Imaging and Tracking Techniques for Inverse Scattering and Wireless Communications." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366202740.

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2

Alkhateeb, Osama. "Singularity-Free Boundary Methods for Electrostatics and Wave Scattering." University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1334816052.

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3

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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4

Moon, Haksu. "Robust Algorithms for Electromagnetic Field Computation with Conduction Currents and Kinetic Charge-Transport Models." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1440193844.

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5

Abumunshar, Anas Jawad. "Tightly Coupled Dipole Array with Integrated Phase Shifters for Millimeter-Wave Connectivity." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1491172877293751.

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6

Peng, Shaoxin. "Direct Evaluation of Hyper-singularity in Integral Equation with Adaptive Mesh Refinement." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1557107644500354.

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7

Fernández, Varea José María. "Interactions of electrons with matter." Doctoral thesis, Universitat de Barcelona, 1992. http://hdl.handle.net/10803/667581.

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The interaction of electrons with matter has been a subject of intense work since the beginning of the century. Although we know that the interaction is purely electromagnetic, its theoretical description is complicated by two different reasons. On the one hand, the number of particles that participate in the interaction may be very large. Even when the target is a single hydrogen atom, the collision is a three body problem for which only approximate solutions of the wave equation are known. Therefore, the interaction can only be treated by using approximate many-body methods. In particular, scattering of fast electrons by single atoms can be reasonably well understood on the basis of independent particle models. On the other hand, when the medium where the projectile moves extends over a. large volume, the projectile may interact repeatedly with the medium. The proper tools to deal with problems involving electron penetration in matter are multiple scattering theories and/or Monte Carlo simulation. The aim of this thesis is to provide a consistent basis for the development of Monte Carlo simulation algorithms which are more accurate than the ones presently available. In fact, a high-energy simulation code based on relevant parts of this thesis is already operable; and a program to simulate electron transport at intermediate and low energies (below about 100 keV) is currently being developed from the theory presented in this work. The reliability of the simulation results obtained with these codes will offer the ultimate demonstration of the correctness and effectiveness of the approaches described here. The thesis is structured in four chapters. Chapter 1 is devoted to the evaluation of reliable single elastic scattering cross sections for high energies. Multiple elastic scattering is considered in detail in chapter 2. Chapter 3 is devoted o the inelastic scattering of low-energy electrons in solids. In chapter4 we consider the energy loss of high-energy electrons and positrons in matter.

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8

Borges, A. Tarisco. "Mental models of electromagnetism." Thesis, University of Reading, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342567.

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9

Skinfill, Craig Ernest. "Electromagnetism in Gravitational Collapse." BYU ScholarsArchive, 2005. https://scholarsarchive.byu.edu/etd/349.

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A numerical approach to including electromagnetism with general relativity is developed using GRAXI as a starting point. We develop a mathematical model describing electromagnetism coupled to a scalar field in an evolving axisymmetric spacetime. As there are numerous formulations of electromagnetism, we evalute different formulations in a limited flat space case. The full curved space system is then developed, using the flat case as a guide to implementing electromagnetism. This model is then implemented using GRAXI as a code base.

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10

Young, André. "Mesh termination schemes for the finite element method in electromagnetics /." Link to the online version, 2007. http://hdl.handle.net/10019/735.

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11

Lei, Feiran. "Homogenization of Heterogeneous Composites by Using Effective Electromagnetic Properties." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1299513068.

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12

Hartman, Gregory. "Monolithically integrated non-reciprocal devices based on magnetic thin films." Wright State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=wright1369095798.

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13

Evers, Chris. "Novel Techniques for Enhancing SAR Imaging using Spatially Variant Apodization." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1304016482.

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14

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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15

Skinfill, Craig Ernest. "Electromagnetism in axisymmetric gravitational collapse /." Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1152.pdf.

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16

Clark, Simon J. "Perturbative gravitation and gravito electromagnetism." Thesis, Lancaster University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250544.

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17

Long, Eamonn. "On charged solitons and electromagnetism." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614274.

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18

Edwards, Robert Stephen. "Uncertainty analyses in computational electromagnetism." Thesis, University of York, 2009. http://etheses.whiterose.ac.uk/14120/.

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19

Caselli, Gabriele. "Some optimization problems in electromagnetism." Doctoral thesis, Università degli studi di Trento, 2022. http://dx.doi.org/10.15168/11572_343343.

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Electromagnetism and optimal control stand out as a topics that feature impactful applications in modern engineering, as well as challenging theoretical aspects of mathematical analysis. Within this context, a major role is played by the search of necessary and sufficient conditions characterizing optimal solutions, as they are functional to numerical algorithms aiming to approximate such solutions. In this thesis, three standalone topics in optimization sharing the underlying framework of Maxwell-related PDEs are discussed. First, I present an optimal control problem driven by a quasi-linear magneto-static obstacle problem featuring first-order differential state constraints. The non-linearity allows to suitably model electromagnetic waves in the presence of ferromagnetic materials, while the first-order obstacle is relevant for applications in the field of magnetic shielding. Existence theory and the derivation of an optimality system are addressed with an approximation technique based on a relaxation-penalization of the variational inequality. Second, I analyze an eddy current problem controlled through a dipole type source, i.e. a Dirac mass with fixed position and variable intensity: well-posedness of the state equation through a fundamental solution (of a curl curl - Id operator) approach and first order conditions are dealt with. To conclude, I discuss the computation of the topological derivative for shape functionals constrained to low-frequency electromagnetic problems (closely related to the eddy current model), with respect to the inclusion/removal of conducting material; the results are obtained using a Lagrangian approach and in particular the so-called averaged adjoint method. This approach requires the study of the asymptotic behavior of the solutions of some problems defined in the whole space, and the introduction and consequent analysis of appropriate function spaces.

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20

Xie, Zhongqiang. "Fourth-order finite difference methods for the time-domain Maxwell equations with applications to scattering by rough surfaces and interfaces." Thesis, Coventry University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369842.

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21

Lalley, Nicholas M. "Composite Electromagnetic Applications and Devices." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1504878841254054.

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22

Esfahani, Pedram. "A Study of the Frequency Dependence of Permittivity and Permeability in Lossless One-Dimensional Composite Right/Left Handed Metamaterials by the Equivalent Circuit Model." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1468524947.

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23

Nouri, Farnoosh Massoudian. "Electromagnetic aftereffects of near-death experiences." Thesis, University of North Texas, 2008. https://digital.library.unt.edu/ark:/67531/metadc9054/.

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The purpose of this quantitative study was first to investigate the comparative incidence of electromagnetic aftereffects (EMEs) during the past year among near-death experiencers (NDErs), people who experienced a close brush with death without an NDE (CBrs), and people who reported never having experienced a close brush with death (LCErs). The second purpose was to investigate a possible change in EME incidence among the three groups before and after a critical life event. The third purpose was to investigate the relationship between the reported overall depth and specific components of the subjective experiences of people who have had a close brush with death -- NDErs and CBrs -- and their reported incidence of EMEs. I used the Near-Death Experience Scale (Greyson, 1983), and developed the Close Brush with Death Question form, Life Changing Event Question form, and Electromagnetic Effects Questionnaire for this study. The final sample included 36 NDErs, 20 CBrs, and 46 LCErs. The results of this study firmly supported more reported problems with EM devices experienced by NDErs compared to CBrs or LCErs. Especially with respect to EM devices such as lights and cell phones, as well as the emotional state of individuals affecting EM devices, this study showed more reports of problems with these devices between before and after NDEs for NDErs compared to before and after a life changing event for LCErs. Moreover, findings of this study showed a correlation between the depth of NDEs and EMEs. This study has important implications for counselors working with NDErs. Findings from this study show that NDErs have a strong possibility of experiencing electromagnetic interferences when close to electromagnetic devices such as cell phones, computers, lights, and watches after their NDEs. This phenomenon can be a stressor in the lives of NDErs and their families and friends. As some participants in this study indicated, information about EMEs can reduce NDErs' stress. Thus, counselors can use information from this study to psychoeducate their NDEr clients and work with them to develop strategies to cope with EMEs, thereby hopefully reducing the stress of EME-related NDE aftereffects.

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24

Thomas, Adam J. "Electromechanical wave analysis through transient magnetic modeling a thesis presented to the faculty of the Graduate School, Tennessee Technological University /." Click to access online, 2009. http://proquest.umi.com/pqdweb?index=12&did=1797274221&SrchMode=1&sid=1&Fmt=6&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1250602024&clientId=28564.

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25

Pryor, Jonothan B. "On ohmic losses in frequency selective surfaces at near-infrared wavelengths." Columbus, Ohio : Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1068663394.

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Thesis (Ph. D.)--Ohio State University, 2003.
Title from first page of PDF file. Document formatted into pages; contains xxiii, 152 p.; also includes graphics (some col.). Includes abstract and vita. Advisor: Benedikt Munk, Dept. of Electrical Engineering. Includes bibliographical references (p. 250-252).

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26

Lin, Chien-Min. "Efficiently computational techniques for solving large-scale electromagnetic problems microstrip interconnects and rough surface scattering /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/5878.

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27

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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28

Giannopoulos, Araham Athanassiou. "On the unification of gravity and electromagnetism." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338737.

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29

Brown, Geoffrey James Nicholas. "Variational principles in atomic collisions and electromagnetism." Thesis, Queen's University Belfast, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335344.

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30

Ratnani, Ahmed. "Isogeometric analysis in plasma physics and electromagnetism." Strasbourg, 2011. https://publication-theses.unistra.fr/public/theses_doctorat/2011/RATNANI_Ahmed_2011.pdf.

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Introduite récemment par Hughes et ses collaborateurs, l’analyse isogéométrique connaît un large succès pour des problèmes principalement industriels. L’idée est de faciliter la communication entre la C. A. O et la simulation numérique, sans avoir à repasser à chaque fois par des mailleurs. Ainsi, les fonctions définissants la géométrie sont utilisées pour approcher les solutions des équations à dérivées partielles. L’application aux problèmes issues de l’électromagnétisme ont été motivé par les travaux de Buffa et ses collaborateurs à Pavie. Dans cette thèse, nous avons appliqué cette méthode pour résoudre des problèmes issues de la physique des plasmas. S’il est vrai que la géométrie n’est pas définie, l’analyse isogéométrique dans sa version isoparamétrique, nous fournit un outil très puissant pour approcher les domaines de calculs. Dans un plasma, ce domaine est défini par la résolution d’un problème d’équilibre (MHD equilibrium). A partir de là, différents modèles sont utilisés pour décrire le plasma: cinétiques (gyrocinétique) ou fluides. Nous avons passé en revue les méthodes les plus classiques et plus utilisées afin de révéler l’intérêt de la méthode. Se basant sur la structure de produit tensoriel, nous avons développé des solveurs rapides pour la résolution de certains problèmes. Nous avons aussi dérivé un solveur, se basant sur les complexes de Hilbert, pour les équations de Maxwell en ”time domain”
The underlying idea behind the IsoGeometric Analysis (IGA), developed recently by Hughes et al, is to use the functions (B-splines/NURBS) that describe the geometry in order to approach the numerical solution of pdes. This reduces the communication between C. A. D system and numerical solvers, and thus is well adapted for industrial problems. The application to Maxwell’s equations was recently motivated by the works of Buffa et al. In this thesis, we apply this new method to solve problems arising from plasmas physics. Even if, in the general case, the geometry is not defined, the IsoGeometric Analysis gives a powerful tool to approach computational domains, and thus can be used in its isoparametric version. In a plasma, this domain can be defined by using an equilibrium problem (MHD equilibrium). Therefor, we can use common models to describe the plasma; this can be done using kinetic (gyrokinetic) or fluid approach. We have adapted the most classical methods using the IGA approach in order to reveal its interest. We were also able to derive some fast solver, based on the tensor product structure. We have also studied Maxwell’s equations for the time domaine problem, and gave a new fast algorithm for its resolution based on Hilbert complexes

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31

Rickard, Yotka. "Improved absorbing boundary conditions for time-domain methods in electromagnetics /." *McMaster only, 2002.

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32

Park, Young C. (Young Chul) 1960. "A Study of Some Biological Effects of Non-Ionizing Electromagnetic Radiation." Thesis, University of North Texas, 1996. https://digital.library.unt.edu/ark:/67531/metadc278105/.

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The experimental studies of this work were done using a microwave cavity spectrometer, Escherichia coli (E-coli) bacteria, and other peripheral equipment. The experiment consists of two steps. First, a general survey of frequencies from 8 GHz to 12 GHz was made. Second, a detailed experiment for specific frequencies selected from the first survey were further studied. Interesting frequency dependent results, such as unusually higher growing or killing rates of E-coli at some frequencies, were found. It is also concluded that some results are genetic, that is, the 2nd, and 3rd subcultures showed the same growing status as the 1st cultures.

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33

Sainath, Kamalesh K. "Robust Numerical Electromagnetic Eigenfunction Expansion Algorithms." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1480340627500682.

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34

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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35

Freitas, Renata Valerio de. "Análise temporal da antena espiral equiangular filamentar." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/3/3142/tde-17032017-091433/.

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Por conta da liberação de uma nova faixa de espectro as aplicações que utilizam transmissão em banda ultralarga se expandiram. Por conta disso, várias formas de transmissão pulsada ganharam destaque. Contudo, o projeto e estudo de antenas até então era majoritariamente feito em banda estreita e regime permanente senoidal. Além disso, para transmissão pulsada, a resposta impulsiva da antena passa a ser mais necessária do que sua resposta em banda estreita. Por isso, o objetivo desse estudo foi explorar o que ocorre com pulsos estreitos se propagando em uma antena de forma a se obter uma aproximação da resposta impulsiva de antenas. Mais especificamente, foi obtido um modelo analítico que explicita a relação entre a geometria e o funcionamento da antena. Através do estudo da espiral equiangular foi possível encontrar o decaimento do pulso de corrente ao longo da linha como também o campo radiado de forma quantitativa. Tal resultado, assim como os procedimentos para sua obtenção, poderá ser utilizado para outras antena filamentares.
The applications for Ultra Wide Band have grown since the new regulation allowed the use of a new large frequency band. Since then, systems for pulsed transmission entered the spotlight. However, the antenna\'s project and study were in big part done in narrowband and sinusoidal steady-state. Besides, the impulse response is of much more interest for these systems than the frequency response. For this reason, the main goal of this work is to explore how current pulses propagate on the antenna to obtain an approximate impulse response. Moreover, an analytical model that unveils the relation between the antenna geometry and its current decay is presented. Through the study of the equiangular spiral it is possible to find the pulse decay as a function of the line length and the radiated field in a quantitative fashion. This result as well as the methods used to obtain it can be used for other antennas.

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Daboo, Cyrus. "Surface plasmon enhanced quantum efficiency of GaAs-Au Schottky diodes." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386416.

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Singh, Rohit. "Structural, Electrical and Magnetic Properties of Ni-Mn-Al based Intermetallics." Thesis, IIT Delhi, 2016. http://localhost:8080/iit/handle/2074/7072.

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38

Irfan, Bushra. "Transport magnetic and galvanomagnetic studies on grown 3D topological insulators of Bi2Se3 and Bi2Te2Se families." Thesis, IIT Delhi, 2016. http://localhost:8080/iit/handle/2074/7055.

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39

Leary, Stephen James. "Investigation of electromagnetism in a real Dirac algebra." Thesis, University of Glasgow, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438622.

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FREITAS, MIGUEL DE ANDRADE. "MONITORING MECHANICAL STRESS ON FLEXIBLE RISERS BY ELECTROMAGNETISM." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2011. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=18757@1.

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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
As técnicas eletromagnéticas de inspeção têm se destacado como as únicas com potencial de determinar, de forma não invasiva, a tensão mecânica nos arames de sustentação dos risers flexíveis. Como o duto flexível é uma estrutura complexa, constituída por várias camadas de aço e de termopl ástico, as técnicas tradicionais de inspeção não são aplicáveis. Alguns métodos magnéticos são capazes de penetrar a camada polimérica externa do riser, porém ainda apresentam limitações e dificuldade na interpretação dos resultados. Não existe hoje, seja no mercado mundial de serviços ou nos diversos grupos de pesquisas que têm se dedicado a este tema, uma solução confiável e definitiva para este problema. O presente trabalho estuda como as diferentes técnicas baseadas em eletromagnetismo podem ser aplicadas na inspeção ou monitoramento da integridade de risers flexíveis. Experimentos e simulações são utilizados para discutir as vantagens e os problemas de cada técnica. Além dos métodos puramente magnéticos estudados, é proposta a aplicação inédita da técnica de ressonância magnetoacústica, também chamada EMAR (Electro Magnetic Acoustic Resonance). Esta técnica gera ondas ultrassônicas no arame através de transdutores eletromagnéticos (EMAT) e é capaz de estimar a tensão mecânica usando as frequências das ressonâncias acústicas. Um novo modelo teórico é proposto para descrever a curva do espectro de ressonâncias acústicas produzidas com EMAR. Anteriormente, estes espectros eram modelados por uma função Lorentziana. Experimentos demonstram que o modelo proposto é significativamente superior, sendo capaz de explicar diversas características dos espectros obtidos. Resultados experimentais mostram a viabilidade do EMAR para estimar a tensão mecânica dos arames, mesmo através da capa, em determinadas circunst âncias. São discutidas as limitações da técnica, casos de uso possíveis e ainda os desenvolvimentos necessários para sua efetiva utilização em campo.
The only inspection techniques that have shown potential to determine, in a non-intrusive fashion, the mechanical stress on armour wires of flexible risers are the electromagnetic-based ones. Because the flexible pipeline is a complex multilayered structure of steel and thermoplastics, traditional inspection techniques cannot be used. Some electromagnetic methods are known to be able to run through the outer polymeric layer to sense the wires but the obtained data are very difficult to interpret. To date there is still no reliable and definitive solution to this problem, neither in the market nor in research groups. This present work analyses how the different electromagnetic techniques can be employed on inspection or monitoring of riser integrity. Experiments and simulations are used to discuss the advantages and limitations of each technique. Besides the purely electromagnetic methods, a novel solution is proposed based on electromagnetic acoustic resonance (EMAR). This technique produces ultrasonic waves on the wire using electromagnetic transducers (EMAT) and is able to estimate the mechanical stress by measuring the frequency of the acoustic resonances. A new line shape calculation is proposed to the acoustic resonances of EMAR. Previously, the spectral data was fitted by a Lorentzian function. The new function is shown to be significantly superior, explaining features of the spectrum not previously described and achieving much better agreement with experimental data. Experiments with flexible pipelines show the viability of using EMAR to estimate the mechanical stress of the wires, even through the outer sheath in some circunstances. The limitations of this technique are discussed, along with possible forms of usage and the pending developments for its effective deployment on the field.

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41

Rabbat, Ralph R. 1978. "Technology enabled science teaching : software framework for electromagnetism." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/84808.

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42

Flood, Stephen. "Exploring the edge of electromagnetism using extreme fields." Thesis, Lancaster University, 2015. http://eprints.lancs.ac.uk/76596/.

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This thesis considers aspects of nonlinear electromagnetism and the eects of spin under the in uence of extreme elds. Born-Infeld-like theories are studied in the context of possible slow light experiments. Maximum amplitude plasma waves are considered as a possible testing ground for nonlinear electrodynamics with regards to electron energy gain. Finally the eects of the coupling between the electromagnetic eld and the spin of a relativistic classical particle are considered via a new derivation of the relativistic Stern-Gerlach and Thomas- Bargmann-Michel-Telegdi equations. These equations are then paired with the Nakano-Tulczyjew condition and, as the Stern-Gerlach-type terms in the equations of motion are most prominent in a eld with a high eld gradient, the impact of spin is investigated in the context of a maximum amplitude plasma wave.

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43

Berry, Yoke. "The effect of pulsed electromagnetic fields on protein unfolding." Access electronically, 2005. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20060713.142625/index.html.

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44

Gronwald, Frank. "Antenna theory in resonating systems derived from fundamental electromagnetism." [S.l.] : [s.n.], 2006. http://diglib.uni-magdeburg.de/Dissertationen/2006/fragronwald.htm.

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45

Bommaraju, Ramaprasad V. "Mold behavior, heat transfer and quality of billets cast with in-mold electromagnetic stirring." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/28628.

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Mold behavior, mold-related quality and the columnar-to-equiaxed transition influenced by in-mold EMS were examined by performing trials at two steel companies, metallurgical examination of the billet samples and mathematical modelling. The thermal fields in the walls of billet molds (102 X 102mm and 127 X 178mm) and in the cooling water were monitored by a system of thermocouples as the EMS was switched on and off during the continuous casting of several heats. The effect of electro-magnetic stirring on mold heat extraction was found to be negligible. The mold temperatures and cooling water temperatures are strongly dependent on the mold/billet gap which is affected by dynamic distortion of the mold tube. In the case of the square mold, the time-dependent mold distortion resulted from boiling adjacent to the cold face due to low water velocity and poor water quality. In the rectangular mold, differential expansion of the wide and narrow faces of the mold led to periodic wall movement at the midface causing cycling in the mold and water temperature. Both effects completely dominated any potential influence of EMS on mold heat extraction. Cooling water velocities measured in separate experiments and the mold temperature profiles were input to a two-dimensional heat-flow model to establish mold heat-flux profiles. A steep taper of 2.6 %/m in the upper regions of the mold increased heat extraction compared to previously published heat-flux data in 0.8 %/m tapered-molds. However, due to the periodic wall movement in the rectangular mold, the heat flux declines to lower values periodically. The calculated heat flux profiles were employed in a one-dimensional transient heat flow model to predict superheat removal from the liquid pool under a variety of assumed fluid flow conditions. The major heat flow effect of EMS was inferred to be one of increasing the convective heat flow at the solidification front leading to earlier superheat extraction from the liquid steel. Solidification structures in billet samples collected during the trials were examined. The columnar-to-equiaxed transition in continuous casting takes place provided all the superheat is removed from the melt and there is a sufficient density of nuclei present in the pool. At superheats of <20° C in the tundish, high heat extraction in the mold and remelting of the mold generated nuclei facilitate the removal of the superheat well within the mold and the columnar-equiaxed transition is triggered after 10-15 mm of shell growth on both the inside and outside radius faces. At higher superheat in the tundish, the liquid pool leaves the mold with residual superheat which takes longer to remove because of the declining fluid flow. Even though all the superheat is removed lower in the machine, the columnar-equiaxed transition occurs only if dendrite debris generated in the vicinity of the mold has survived in their descent through the superheated liquid. The effect of carbon on the columnar-to-equiaxed transition appears to stem from its influence on facilitating dendrite arm remelting and the survival of the dendrite fragments till the pool reaches sub-liquidus temperature. EMS extracts more superheat by maintaining a steep temperature gradient in the thermal boundary ahead of the solidification front and achieves an earlier columnar-equiaxed transition. Electro-magnetic stirring appears not to affect either the average depth or the variation of depth of oscillation marks across a given face. However, the electro-magnetically driven flow dominates the turbulance at the meniscus due to the input stream and stabilizes a meniscus shape with the result that the oscillation marks are also of a well-defined shape unlike the unstirred billets. No influence of EMS was found on the formation of "hooks" or the fine equiaxed crystal zone near the surface. The influence of EMS on inclining the growing dendrites appears to not come into effect until about 1 mm of shell has formed. It appears that the existence of the momentum boundary layer where the velocity of the rotating steel falls to zero at the surface is the reason for the absence of the influence of EMS on the subsurface solidification. Rhomboidity and off-corner crack formation were found to depend, as reported by previous researchers, on mold distortion and its dynamic nature. The absence of any effect of EMS on these defects is due to its lack of effect on mold heat transfer and thus mold distortion.
Applied Science, Faculty of
Materials Engineering, Department of
Graduate

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46

Cohen, Marc 1964. "Bioenergetics, information and acupuncture : an exploration of the links between acupuncture information, and bio-electromagnetism." Monash University, Dept. of Electrical and Computer Systems Engineering, 2000. http://arrow.monash.edu.au/hdl/1959.1/7851.

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47

Ayyildiz, Kasim. "Surface integral solution of chiral loaded waveguides of arbitrary cross section." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2006. http://proquest.umi.com/login?COPT=REJTPTU0NWQmSU5UPTAmVkVSPTI=&clientId=3739.

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48

Marchand, Renier Gustav. "Fine element tearing and interconnecting for the electromagnetic vector wave equation in two dimensions /." Link to online version, 2007. http://hdl.handle.net/10019/363.

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49

Gadsdon, Martyn Richard. "The optical response of rectangular metallic gratings and metal/dielectric multilayers." Thesis, University of Exeter, 2008. http://hdl.handle.net/10036/71987.

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The ability of periodic surface variations to influence and control the electromagnetic response of interfaces and structures has been recognised for many years. Concurrently with these investigations, it has been found that individual particles and wires support interesting electromagnetic resonances. It has also long been established that multi-layer structures of planar interfaces may also result in interesting electromagnetic responses. Multi-layer structures of alternating dielectrics have been shown to produce periodic transmission resonances, however, if one of the dielectrics is replaced with a thin metallic film, it has recently been demonstrated that wide band-pass regions are formed in the electromagnetic response of the structure. The work presented in this thesis can be considered to be separated into two distinct, but related, areas. One of the areas involves the analysis of wire grid arrays. It is demonstrated that, like the case of deep surface relief perturbations, the waveguide modes in the slits can be considered as the evolution of surface modes on shallow surface relief perturbations. The perturbation effects of the slits on the surface modes and the effect of their excitation on optically thick and thin wires are also investigated. Finally, a new electromagnetic resonance is presented on both 1-dimensional and 2-dimensional wire grid arrays. It is shown that this is closely related to the localised surface modes that have been shown to occur on individual particles and wires. However, the resonance presented is shown to be subtly different from these modes, which typically result in a transmission and reflection extinction, because the planar geometry of the wires and the periodicity result in a reflection enhancement, even when the wires are optically thin. The second area of this work may be separated into two distinct sub-sections. The first section examines the electromagnetic response of dielectric/metal multi-layer stacks. These are confirmed to exhibit a periodic series of broad band-pass regions, with the spectral location of these regions being dependent only on the unit cell, not the full extent of the structures. The location of each band-edge of these regions are then demonstrated to be a result of the matching of boundary conditions between standing waves in the cavities having either a cos or a sin standing wave function, and the evanescent fields inside the metal layers having either a sinh or a cosh field distribution. The second section examines the electromagnetic response of continuous surface relief gratings, with a rectangular cross-section, whose ridges are very thin. It is shown that vertical standing waves form, similar to the cavity waveguide modes, except with the fields coupled through the wires not across the grooves. These are then shown to reach a finite limit frequency as the grating height tends to infinity. Thus, the resonances have evolved into a different mode beyond a certain grating amplitude. This mode is shown to to be equivalent to the band-pass region described in multi-layer metal/dielectric stacks. However, scattering and periodicity considerations require that only the low frequency band-edge can be coupled to at normal incidence, while only the high frequency band-edge may be coupled to at grazing incidence.

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Hong, Jia-Sheng. "Electromagnetic forces in flexible systems." Thesis, University of Oxford, 1994. http://ora.ox.ac.uk/objects/uuid:ab6b986e-7b24-4fee-9410-aa4e92249b03.

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Some problems in electro dynamics have been studied in the light of electromagnetic field theory and computational techniques. One is that of the retrograde motion of the electric arc – an old and intriguing problem of physics. A more complete model based on electrodynamics has been proposed for study of this problem. In this model, the plasma column is treated as a flexible conductor. The associated 3-dimensional boundary-value problem was solved by the boundary element method (BEM). It has been shown that the retrograde motion can indeed be understood in terms of electrodynamics and a number of the reported features of this phenomenon have been explained by the proposed model. The others are concerned with a recent controversy in electrodynamics. It has been discussed in the thesis that Lorentz and Ampere force laws are equivalent in the sense of magnetostatics provided that the latter is appropriately used. The interactions of electromagnetic forces on the systems of the electromagnetic jet propulsion and the electromagnetic impulse pendulum have been examined. It turns out that the observations are consistent with the laws of electromagnetic energy and momentum. Two aspects of the water-arc explosion problem have been studied. One is the electromagnetic (EM) aspect which is calculated by the method of separation of the variables, the other is the magnetohydrodyuamic (MHD) aspect which is solved by the finite difference method (FDM). The numerical results of the two aspects show that neither the pure EM model nor the MHD model for the incompressible fluid could explain the explosive phenomenon; this strongly suggests that the shock wave produced by the under-water arc must account for the phenomenon. On the wire fragmentation, a preliminary study has shown that this phenomenon could be caused by the electromagnetically driven stress waves and a theoretical model has been proposed for further investigation. This is described in an Appendix to the thesis.

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