Dissertations / Theses: 'Electromagnetic applications'

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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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Adamu, Tigist Atnafseged. "Electromagnetic Interference in Dwnhole Applications." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elkraftteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19394.

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SummaryElectromagnetic compatibility (EMC) and electromagnetic interference (EMI) are topics which have been of concern to electrical industry for many years. Excessive generation of electromagnetic noise and interference, resulting inadequate EMC, is one potential source of interaction and performance degradation which may reduce operational effectiveness of the devices. Because of this, EMC testing services and regulation imposed by governments have forced product designer to pay close attention electromagnetic interference level of their products.For improving oil and gas production recovery, from mature fields and for exploitation of deep and ultra-deep offshore reservoirs new downhole technologies are required. Electrification of downhole applications has proven to be very promising and the technologies are designed for deployment in harsh environments. This master thesis deals with the study of EMI problems for downhole drive train system especially caused by EMI phenomena. The two aspects of EMI and EMC are studied, the manner in which how EMI can generate and propagate then affect receptor or victim intentionally and unintentionally are discussed. Followed by types of EMI phenomena (voltage dip, electrostatic discharge (ESD), surge, fast transient and rapid voltage change (dv/dt)) their occurrence and adverse effects of them are studied. dv/dt, overvoltage and EMI filter types are studied and designed. Compressions are made by their performance, size, power loss and cost. To verify their performance simulation model are made for downhole drive system to filter dv/dt and overvoltage at the motor terminals.After having the theoretical base, practical pre-compliance conducted EMI measurements are made for single phase chopper and three phase inverter.The influence of EMI such as reverse recovery current of diode, stray or leakage inductance, gate drive resistance, heat sink grounding, duty cycle and switching frequency are investigated on the single phase chopper. An LfCf harmonic filter is designed and placed between the inverter and motor terminals and differential mode EMI noise is measured in the system.

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Weng, Wei-Chung. "Taguchi's method for optimizing electromagnetic applications /." Full text available from ProQuest UM Digital Dissertations, 2007. http://0-proquest.umi.com.umiss.lib.olemiss.edu/pqdweb?index=0&did=1414125771&SrchMode=1&sid=1&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1221160089&clientId=22256.

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Richens, P. E. "High temperature superconductors in electromagnetic applications." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365792.

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Ekstrand, Vilhelm. "Therapeutic applications of acoustic and electromagnetic energy /." Stockholm, 2005. http://diss.kib.ki.se/2005/91-7140-126-1/.

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Miller, Raanan Ariel Tai Yu-Chong Tai Yu-Chong. "Microfabricated electromagnetic flap actuators and their applications /." Diss., Pasadena, Calif. : California Institute of Technology, 1997. http://resolver.caltech.edu/CaltechETD:etd-01142008-081338.

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Tang, Wenxuan. "Coordinate transformation based electromagnetic design and applications." Thesis, Queen Mary, University of London, 2012. http://qmro.qmul.ac.uk/xmlui/handle/123456789/8695.

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The main objective of this thesis is to take one step forward to practical and realisable devices for antenna and microwave engineering, using the technique of discrete coordinate transformation (DCT), which is a practical implementation of the coordinate transformation method. During this thesis, the DCT technique was demonstrated and analysed from the theory, and was proved to provide an all-dielectric approach to design devices under certain conditions. Two schemes were proposed on how to use this technique in a practical design. The first one is to transform an existing device into a flattened profile, meanwhile maintaining its electromagnetic performance. As examples, a flat reflector and a flat lens were created from a parabolic reflector and a convex lens, respectively. The second scheme is to project the propagating paths of an electromagnetic wave, and then generate a distorted space according to the paths by engineering the electromagnetic properties of the media. In this scheme, two examples of application were presented: an undetectable antenna composed of a carpet cloak and a conducting cavity, and a broadband device which can extraordinarily enhance the transmission through a sub-wavelength aperture. Numerical simulations based on the Finite-Difference Time-Domain (FDTD) method were implemented to verify all the designs. Several specific configurations were employed in the modelling in order to simulate the DCT based devices more efficiently and precisely. Performance of these devices was validated and analysed, and the advantages and disadvantages of this technique were investigated. Realisation and fabrication methods i were also studied, and a prototype was designed, fabricated and measured. At the end, as an extension, a multiple discrete coordinate transformation method was proposed and presented. This multiple transformation was proved to effectively relax the limitation of the one-step transformation, and was used to design an all-dielectric thin absorber from a conventional pyramidal one for demonstration.

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Huang, Xianjun. "Electromagnetic applications of graphene and graphene oxide." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/electromagnetic-applications-of-graphene-and-graphene-oxide(873c9618-19a3-4818-b47a-9afbca39857c).html.

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Since the isolation of graphene in 2004, a large amount of research has been directed at 2D materials and their applications due to their unique characteristics. This thesis delivers pioneering developments on the applications of graphene and graphene oxide (GO) on electromagnetic ranges such as radio frequency, microwave frequency and THz bands, and specifically 2D materials based antennas, absorbers, sensors and etc. This thesis focuses on exploring electromagnetic applications of monolayer graphene, printed graphene and graphene oxide. In study of monolayer graphene applications, the theoretical and simulation studies are carried out to design tunable terahertz (THz) absorbers, tunable microwave wideband absorbers, and reconfigurable antennas, etc. These studies on the applications of monolayer graphene have proved prospective potentials of graphene in THz sensing, RCS reduction, and reconfigurable antennas. This thesis also presents pioneering advances on electromagnetic applications of printed graphene. Among these works, low-cost highly conductive and mechanically flexible printed graphene is developed for radio frequency (RF) applications. For the first time, effective RF radiation of printed graphene is experimentally demonstrated. Based on these results, applications of printed graphene including RFID (radio frequency identification) tags, anti-tampering RFID, EMI shielding, flexible microwave components such as transmission lines, resonators and antennas, conformable wideband radar absorbers, graphene oxide based wireless sensors, etc. are developed and experimentally demonstrated. This work significantly expands applications of graphene in electromagnetic areas.

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Mahmoud, Hany Mostafa Mohamed Elsaid. "High-speed applications for electromagnetic propulsion technology." Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/21373/.

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In this thesis, different types of the magnetic lead screw systems are considered, and the effects of the key design parameters, such as magnet thickness, air-gap length, pole-pitch, number of pole-pairs, dimension etc. on the force/torque transmission are investigated. Moreover, research into the realisation of helical magnetisation distribution employing a novel impulse magnetisation process is undertaken, in order to reduce the complexity and cost of manufacture. This avoids the complex and/or time-consuming methods, which may require the assembly of a large number of small magnets to approximate helical magnetisation distribution. A prototype reluctance type magnetic screw system is realised, it consists of a double start mechanical screw and a permanent magnet nut equipped with impulse magnetised cylindrical permanent magnets, using purpose designed double-sided impulse magnetising fixture. Furthermore, a test-rig to measure the transmitted force is developed and used to compare the predicted and measured results.

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Anderson, Erik Hyde. "Fabrication and electromagnetic applications of periodic nanostructures." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/13436.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1988.
Includes bibliographical references (leaves 111-117).
by Erik Hyde Anderson.
Ph.D.

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Rafiq, Muhammad Nadeem. "Carbon Microfiber Material for Electromagnetic (Shielding) Applications." Diss., North Dakota State University, 2015. http://hdl.handle.net/10365/25293.

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Electromagnetic shielding is becoming more and more important with the abundance of wireless devices. Therefore a need has arisen for more versatile, flexible and low-cost solutions for shielding. For these requirements, carbon microfiber material has been proposed for electromagnetic shielding applications. For this purpose its shielding effectiveness has been measured and modeled in a simulation environment. A parametric simulation was conducted for the material property ?conductivity? and the results were compared to measured ones. These simulation results were also verified by the analytical solution for the shielding effectiveness and the agreement between the simulated values and analytical results demonstrated that the carbon microfiber material, though having less conductivity than the traditional metallic shields is a good candidate for electromagnetic shielding applications. Carbon microfiber not only provides comparable shielding effectiveness to a metallic shield but it can be advantageous because of its light weight, corrosion resistance and flexibility. Also, its porous nature can help with cooling of enclosed electronic circuits.
COMSATS Institute of Information Technology, Pakistan
North Dakota State University (NDSU)

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Ramesh, Prashanth. "Smart Materials for Electromagnetic and Optical Applications." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1343821988.

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Khan, Syed Farid Ullah. "Vibration-based electromagnetic energy harvesters for MEMS applications." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/33833.

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This thesis investigates vibration-based electromagnetic energy harvesters (EMEHs) for application in low power autonomous sensors. It makes contributions pertaining to the development of a low cost fabrication technology, analytical modeling, simulations and characterization of EMEHs under harmonic and random vibrations. A novel, low cost, one mask fabrication technology devised in this thesis is used to develop a copper foil-type linear EMEH, and a polydimethylsiloxane (PDMS) membrane type nonlinear EMEH. The voltage and power generated by these harvesters are comparable to existing EMEHs which use more involved fabrication processes. In the membrane type EMEH the inclusion of a more flexible PDMS membrane design reduces the harvester resonant frequency and makes it suitable for extracting energy from low level vibration environments. For acceleration levels greater than 0.1 g, this harvester exhibits a nonlinear behaviour. At higher levels of narrow band random excitations, the device therefore exhibits broadening of the load voltage spectrum in comparison to the response under relatively low levels of narrow band random excitations. Analytical models for linear EMEHs with non-uniform magnetic field for harmonic vibrations are developed. A simple analytical model based on Faraday’s law and uniform gradient of the normal component of the magnetic flux density is developed for EMEHs where the entire coil experiences approximately the same gradient of the normal component of the magnetic flux density. However, for EMEHs where the entire coil is not exposed to the same magnetic flux gradient a more robust model, based on the off-center analytical solution of the magnetic flux density is devised. The simulation results of the developed models are in good agreement with the experimental observations. Analytical models for linear and nonlinear EMEHs under random vibrations are derived. The models are parameterized such that they are applicable to all architectures of EMEHs and can be utilized for designing and performance estimation of EMEHs. Nonlinear harvesters with spring nonlinearity and with combined spring and damping nonlinearity are modeled using the statistical linearization method. The developed models are useful in investigating the effects of the mechanical nonlinearity on the performance and bandwidth of the harvesters under random vibrations.

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Azpúrua, Marco A. "Full time-domain electromagnetic interference measurements and applications." Doctoral thesis, Universitat Politècnica de Catalunya, 2018. http://hdl.handle.net/10803/587194.

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This thesis presents a technology that has been called the Full Time-Domain Electromagnetic Interference measurement systems and its applications. Full TDEMI measurement systems are an implementation of an FFT-based receiver that enables the usage of oscilloscopes for EMI measurements. They follow the virtual instrumentation approach for transforming oscilloscopes into a compliant CISPR 16-1-1 receiver. Full TDEMI measurement systems have been assessed for characterizing their performance using waveform oriented calibration procedures that bridge the gap between direct measurements in the time domain and the processed frequency domain magnitudes. As a result, the conformity of Full TDEMI receivers is attested with respect to the requirements defined in the standards. Full TDEMI systems have advantages over the conventional swept receivers for performing challenging measurements typical of EMI assessments. Time-domain captures enable full spectrum measurements that allow analyzing transient phenomena. The number of channels available in most oscilloscopes enable synchronous measurements that allow recording the EMI using a combination of transducers. Some of the applications of the multichannel EMI measurements are the single stage evaluation of the conducted EMI of all the EUT mains lines, the instantaneous measurement of the common-mode and the differential mode voltage noise, the concurrent conducted and radiated EMI measurements, and the parallelization of multi-antenna radiated emissions testing. Such alternative test methods, have improved the EMC testing process in a variety of industries by reducing the time and the efforts required for performing a complete EMI evaluation due to the following reasons. First, Full TDEMI measurements deliver faster results because the interferences' spectrum is simultaneously estimated for all the weighting detectors. Second, the number of measurement iterations is reduced because of the multichannel possibilities and also because of an agile identification of the worst case emissions. Thirdly, Full TDEMI measurement system are a cost-effective alternative to the real-time spectrum analysers. Full TDEMI measurement systems have extended the state-of-the-art with the expected maximum detector and the empirical interference decomposition. The expected maximum detector is a statistical measure of the most probable level of the peak emissions that is based on a time-frequency modelling of the measured EMI using the extreme value theory. Using the variability information of the EMI level at each frequency bin, the expected maximum detector estimates the equivalent max hold value of a random EMI. The expected maximum detector also provides a model for quantifying the uncertainty of peak detector measurement of stochastic EMI. The Empirical Interference Decomposition is a modified implementation of the Hilbert-Huang transform with time-gating capabilities that allow a heuristic determination of characteristic oscillatory patterns without neither domain transformation nor a predefined set of basis function. The EID has been used successfully for ambient noise cancellation purposes during outdoor EMI measurements, obtaining more than 20 dB of attenuation of the usual broadcasting signals. The fundamentals of the ANC by means of EID is the identification, in the time and in the frequency domain, of intrinsic modes of emissions that area attributable to the EUT while subtracting the residual modes from the measurement results. Applications of the Full TDEMI measurement systems have been published in recognized conferences and journal. From the reasons mentioned before, the Full TDEMI measurement technology has advantages for EMI testing, analyzing and troubleshooting. It provides a complementary approach to the typical measurements entirely focused in the frequency domain and it exhibits a level of maturity that could allow it to be standardized in forthcoming years.
Esta Tesis comprende un compendio de contribuciones hechas por el autor al campo de la tecnología de medición de radiofrecuencia para la compatibilidad electromagnética. En particular, esta Tesis presenta una tecnología de sistemas medición de interferencias electromagnéticas completamente basado en dominio del tiempo (Full TDEMI) y algunas de sus aplicaciones más relevantes. Los sistemas de medición Full TDEMI son una implementación de un receptor de medida basado en FFT que permite el uso de osciloscopios para mediciones de interferencias electromagnéticas. Los sistemas de medición Full TDEMI siguen el enfoque de instrumentación virtual para transformar los osciloscopios de propósito general en un receptor de medida completamente funcional y conforme con la norma CISPR 16-1-1. Por un lado, esto es factible debido a las técnicas específicas de procesamiento de señales aplicadas sobre las adquisiciones en el dominio del tiempo utilizando una capa de software dedicada. Por otro lado, los sistemas de medida Full TDEMI se han evaluado exhaustivamente para caracterizar su rendimiento utilizando procedimientos novedosos de calibración orientados a formas de onda que acortan la brecha entre las magnitudes medidas en el dominio del tiempo y las aquellas procesadas en el dominio de frecuencia. Como resultado, se certifica la conformidad de los sistemas completos de medición TDEMI con respecto a los requisitos definidos en los estándares internacionales paramediciones EMI. Además, se ha demostrado que los sistemas de medición Full TDEMI ofrecen ventajas en comparación con los receptores de barrido convencionales para realizar varias medidas desafiantes típicas de las evaluaciones de emisiones electromagnéticas. Por ejemplo, las capturas de dominio de tiempo posibilitan mediciones de espectro completo que permiten un análisis adecuado de fenómenos transitorios. Del mismo modo, la cantidad de canales disponibles en la mayoría de los osciloscopios hace viables múltiples mediciones síncronas que para registrar las perturbaciones interferentes mediante una combinación de transductores. Algunas de las aplicaciones de la medición EMI multicanal son la evaluación de etapa única de la EMI conducida de todas las líneas de alimentación de los equipos bajo prueba (EUT), la medición instantánea del voltaje del ruido en modo común y en modo diferencial, las mediciones concurrentes de la EMI conducida y radiada y la paralelización de los ensayos de emisiones radiadas con múltiples antenas. Tales métodos de prueba alternativos, han mejorado significativamente el proceso de prueba de EMC en una variedad de industrias al reducir la cantidad de tiempo y los esfuerzos necesarios para realizar una evaluación completa del sistema principalmente debido a las siguientes razones. En primer lugar, las mediciones de EMI en el dominio del tiempo arrojan resultados más rápidos porque el espectro de interferencias se estima simultáneamente para todos los detectores de ponderación estándar necesarios para determinar el cumplimiento de los límites máximos de emisiones definidos en las respectivas normas de producto. En segundo lugar, el número de iteraciones de medición se reduce debido a las posibilidades multicanal y también debido a una identificación ágil del peor caso de las emisiones de un EUT que tiene diferentes modos de funcionamiento. En tercer lugar, el sistema Full TDEMI es una alternativa económica y versátil a los analizadores de espectro en tiempo real más avanzados en lo concerniente a mediciones EMI en el rango de pocos gigahertzios. Desde el punto de vista teórico, los sistemas de medición Full TDEMI han extendido el estado del arte, como en el caso de un par de contribuciones denominadas el detector de máximo esperado y la descomposición empírica de interferencias. El detector de máximo esperado es una medida estadística del nivel más probable de las emisiones pico que se basa en un modelado tiempo-frecuencia de las interferencias medidas utilizando la teoría del valor extremo. Usando la información de variabilidad del nivel de interferencia en cada componente de frecuencia, el detector de máximo esperado se puede usar para estimar el valor de retención máximo (max-hold) equivalente de una interferencia aleatoria. El detector demáximo esperado también proporciona un modelo que cuantifica la incertidumbre de lamedición del detector de picos ante interferencias estocásticas. La descomposición de interferencia empírica (EID) es una implementación modificada de la transformada de Hilbert-Huang con capacidades de sincronización de tiempo que permiten una determinación heurística de patrones oscilatorios característicos sin requerir transformación de dominio ni un conjunto predefinido de funciones base. La descomposición de la interferencia empírica se ha utilizado con éxito para la cancelación del ruido ambiental durante prueba de concepto de mediciones de EMI de al aire libre, obteniendo más de 20 dB de atenuación de las señales habituales de radiodifusión. El fundamento de la cancelación del ruido ambiental mediante EID es la identificación, en el tiempo y en el dominio de la frecuencia, de los modos de emisión intrínsecos que son atribuibles al EUT al restar los modos residuales (ruido ambiental) de los resultados de medición. Las contribuciones mencionadas se distribuyen en cuatro artículos de revista. Los resultados de medición complementarios y las aplicaciones de los sistemas de medición Full TDEMI también se han publicado en conferencias notables en el área. Por los motivos antes mencionados, la tecnología Full TDEMI tiene ventajas significativas para los ensayos, el análisis y la resolución de problemas de EMI. Asimismo, proporciona un enfoque complementario a las mediciones típicas completamente enfocadas en el dominio de la frecuencia y exhibe un nivel de madurez que podría permitir su estandarización en los próximos años.

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Mujat, Mircea. "POLARIMETRIC CHARACTERIZATION OF RANDOM ELECTROMAGNETIC BEAMS AND APPLICATIONS." Doctoral diss., University of Central Florida, 2004. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4495.

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Polarimetry is one of the principal means of investigating the interaction of light with matter. Theoretical models and experimental techniques are presented in this dissertation for polarimetric characterization of random electromagnetic beams and of signatures of random media in different scattering regimes and configurations. The degree of polarization rather than the full description of the state of polarization is of interest in multiple scattering and free space propagation where the statistical nature and not the deterministic component of light bears the relevant information. A new interferometric technique for determining the degree of polarization by measuring the intensity fluctuations in a Mach- Zehnder interferometric setup is developed. For this type of investigations, one also needs a light source with a controllable degree of polarization. Therefore, also based on a Mach-Zehnder interferometer, we proposed a new method for generating complex random electromagnetic beams. As a direct application of the cross-spectral density matrix formalism, it is shown that the spectral and the polarimetric characteristics of light can be controlled by adjusting the correlations between parallel components of polarization propagating through the two arms of the interferometer. When optical beams are superposed in the previous applications it is desirable to understand how their coherence and polarimetric characteristics are combined. A generalization of the interference laws of Fresnel and Arago is introduced and as a direct application, a new imaging polarimeter based on a modified Sagnac interferometer is demonstrated. The system allows full polarimetric description of complex random electromagnetic beams. In applications such as active illumination sensing or imaging through turbid media, one can control the orientation of the incident state of polarization such that, in a given coordinate system, the intensities are equal along orthogonal directions. In this situation, our novel interferometric technique has a significant advantage over standard Stokes imaging polarimetry: one needs only one image to obtain both the degree of polarization and the retardance, as opposed to at least three required in classical Stokes polarimetry. The measurement of the state of polarization is required for analyzing the polarization transfer through systems that alter it. Two innovative Mueller matrix measurement techniques are developed for characterizing scattering media, either in quasi real-time, or by detection of low level signals. As a practical aspect of Mueller polarimetry, a procedure for selecting the input Stokes vectors is proposed. The polarimetric signatures of different particulate systems are related to their structural properties and to the size distribution, shape, orientation, birefringent or dichroic properties of the particles. Various scattering regimes and different geometries are discussed for applications relevant to the biomedical field, material science, and remote sensing. The analysis is intended to elucidate practical aspects of single and multiple scattering on polydisperse systems that were not investigated before. It seems to be generally accepted that depolarization effects can only be associated to multiple scattering. It is demonstrated in this dissertation that depolarization can also be regarded as an indication of polydispersity in single scattering. In order to quantify the polarizing behavior of partially oriented cylinders, the polarization transfer for systems consisting of individual layers of partially aligned fibers with different degrees of alignment and packing fractions is also analyzed in this dissertation. It is demonstrated that a certain degree of alignment has the effect of a partial polarizer and that the efficiency of this polarizer depends on the degree of alignment and on the packing fraction of the system. In specific applications such as long range target identification, it is important to know what type of polarization is better preserved during propagation. The experimental results demonstrate that for spherical particles smaller than the wavelength of light, linear polarization is better preserved than circular polarization when light propagates through turbulent media. For large particles, the situation is reversed; circular polarization is better preserved. It is also demonstrated here that this is not necessarily true for polyhedral or cylindrical particles, which behave differently. Optical activity manifests as either circular birefringence or circular dichroism. In this dissertation, a study is presented where both the effect of optical activity and that of multiple scattering are considered. This situation is relevant for medical applications and remote sensing of biological material. It is demonstrated here that the output state of polarization strongly depends on the optical density of the scattering medium, the optical rotatory power and the amount of circular dichroism associated to the scattering medium. This study shows that in the circular birefringence case, scattering and optical activity work together in depolarizing light, while in the dichroic case the two effects compete with each other and the result is a preservation of the degree of polarization. To characterize highly diffusive media, a very simple model is developed, in which the scattering is analyzed using the Mueller matrix formalism in terms of surface and volume contributions.
Ph.D.
Optics and Photonics
Optics and Photonics;
Optics

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Naeem, Majid. "Theory, modelling, and applications of advanced electromagnetic materials." Thesis, Queen Mary, University of London, 2017. http://qmro.qmul.ac.uk/xmlui/handle/123456789/31858.

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A multitude of recent work predicts many novel concepts based on the availability of non-natural materials; some prominent examples include transformation optics (TO) and perfect lens. The interest in this eld has grown dramatically due to spec- ulated possibility to allow for continuously varying material properties to steer the incident wave at will, such as for the TO. The posed challenges for their realisation include the limitations of numerical modelling and manufacturing techniques. A de- sign scheme has been proposed, in this thesis, for composite materials: the desired electromagnetic properties of composites can be engineered by judiciously varying the volume fraction of the inclusion-to-host materials, by manipulating the geomet- ric arrangement of inclusions, or by altering their dielectric contrast. The analysis of the homogenised response of the designed materials at macro-scale requires effective medium modelling techniques. The existing effective medium approximation tech- niques have been discussed, and their pros and cons outlined. A homogenization scheme has been introduced that is based on the interaction of the incident wave and the nanoparticles at the micro-scale, which further requires efficient electromagnetic modelling. The conventional nanoparticle modelling techniques, as well as the state of the art, have been reviewed and a dipole-moment-based method to efficiently solve modern nanoparticle-based electromagnetic problems has been outlined. The appli- cability of the proposed scheme has been demonstrated by employing it to design various EM devices. An improved permittivity extraction scheme has been proposed for the homogenization of composites. Unlike classical homogenization schemes, the extracted parameters, using the proposed technique, follow the relation between the real and imaginary parts, that is, Kramers-Kronig relations. Several random and periodic structures have been simulated for the purpose of extracting the ef- fective electromagnetic properties and interpreting the results so as to establish a connection between them.

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Odabasi, Hayrettin. "Novel Metamaterial Blueprints and Elements for Electromagnetic Applications." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366281874.

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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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Liu, Zhejie. "Investigation of coupled thermo-electromagnetic problems in relation to applications of permanent magnets to electromagnetic devices." Thesis, University of Liverpool, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239956.

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Gope, Dipanjan. "Integral equation based fast electromagnetic solvers for circuit applications /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/6116.

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Karlsson, Roger. "Theory and Applications of Tri-Axial Electromagnetic Field Measurements." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-5916.

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Sudhakaran, Sunil. "Negative refraction from electromagnetic periodic structures and its applications." Thesis, Queen Mary, University of London, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.430074.

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Alhajeri, Salem Hasan Hamad. "Online electromagnetic wave monitoring system for petroleum industry applications." Thesis, Liverpool John Moores University, 2010. http://researchonline.ljmu.ac.uk/5939/.

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The general demand for automating industrial processes in the oil industry has increased rapidly in parallel with sensors and their underlying technology. Since the early 1980s, the particular problem, which has been representing the extremes in complexity in the oil industry, is the measurement of multiphase flow components, the mixing ratio of oil, water, and gas flowing in a pipeline. Electromagnetic (EM) Wave sensors can provide an attractive solution, because microwave signals can penetrate most materials allowing the measurement to be representative for the cross section of the pipeline. In this thesis, EM wave sensors operating at microwave frequencies are developed for measuring multiphase flow components in a pipeline. These sensors are based on cylindrical cavity, and they use the resonant frequencies related to changes of permittivity to detect and measure (oil, gas, and water) components flowing in a pipeline. Special emphasis has been given to three main design principles. The principle of designing a completely non intrusive sensor, the choice of resonance mode to achieve the best measurement accuracy, and the possibility of designing a new software application to allow online implementation of the sensors. The first principle is shown to allow sensorswith completely non intrusive structures to be designed. The two fundamental modes in cylindrical cavity resonators were therefore analysed. A sensor for measuring the mixture ratio of oil and water flowing in a pipeline is developed. We called it a EM wave (EMW2) for measuring two phase. Both the experiment results and the HFSS results are compared and analysed. A sensor for measuring multiphase flow (oil, gas, and water mixtures) in a pipeline in real time is developed. We called it a EW wave (EMW3) sensor for multiphase fractions measurement. The emphasis is on the measurement accuracy with the desired resonant frequency mode, and the possibility of designing a software programme to explore the functionality of the sensor for online measurement. The accuracy of the sensor measurements is achieved by comparing and analyzing the HFSS simulated results and experimental results. A sensor suitable for measuring online the components of mixtures of (hydrocarbons, gas, and water) flowing in a pipeline is developed based on the EMW3 sensor. We called it a EM Wave monitoring and control system. Consequently, online controlling and monitoring, on the other hand, are achieved and the online results are shown. Finally, the research is concluded and future works is discussed.

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Chew, W. M. "Optimum electromagnetic design for wound components in SMPS applications." Thesis, University of Bath, 1989. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328339.

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Carpentieri, Bruno. "Sparse preconditioners for dense linear systems from electromagnetic applications." Toulouse, INPT, 2002. http://www.theses.fr/2002INPT007H.

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Dans cette thèse, nous étudions des préconditionneurs creux par inverse approché pour la résolution de systèmes linéaires denses issus d'applications en électromagnétisme en formulation intégrale. L'objectif de ce travail était le développement de préconditionneurs robustes et parallèles pouvant être intégrés ultérieurement dans des codes de simulation capables de traiter des géométries industrielles de très grandes échelles. Dans un premier temps, nous avons réalisé une étude comparative des divers préconditionneurs initialement développés en algèbre linéaire creuse en les adaptant au traitement des matrices denses. En particulier, nous avons proposé une stratégie efficace permettant de définir à priori la structure creuse d'un préconditionneur basé sur un inverse approché minimisant la norme de Frobénius. Cette approche a été implantée par un autre doctorant dans un code parallèle qui exploite une méthode "fast multipole" pour le calcul de l'opération produit matrice-vecteur dans les méthodes de Krylov. Ce code nous a permis d'évaluer l'évolutivité de notre préconditionneur lors de la résolution de systèmes linéaires de taille croissante et d'en caractériser les limitations. Afin de repousser ces limitations, nous avons proposé un schéma numérique basé sur des itérations emboîtées qui nous a permis d'améliorer notablement la robustesse de notre préconditionneur sur des problèmes de grande taille. Cette technique nous a permis de réduire les coûts de calcul ainsi que de pouvoir traiter des géométries complexes telle que celle d'un avion avec plus d'un million de degrés de liberté. Enfin, nous avons également réalisé une étude préliminaire sur des préconditionneurs 2 niveaux spectraux qui exploitent des propriétés spectrales du système préconditionné.

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Chen, Te-Chuan, and Te-Chuan Chen. "Novel Electromagnetic Structure, Circuit, and Material for Microwave Applications." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/626697.

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This dissertation presents the investigation of novel electromagnetic structure, circuit, and material for microwave engineering. There are four topics covered in this work: the study of a waveguide filter at W-band frequencies using electromagnetic crystal (EMXT) surfaces, the design of a dual-band amplifier with flexible frequency ratio, the analysis and testing of a compact 4:1 planar combiner with complex matching, and the investigation of a dielectric nanostructured material using a mixture of polymer and silver nanoparticles. First, a rectangular waveguide band-stop filter using electromagnetic crystal EMXT surfaces is presented. A waveguide is loaded on the top and/or the bottom walls with EMXT surface, which has a propagating band gap. An equivalent circuit is developed to model the filter behavior and to predict its stop band. A W-band prototype based on the proposed filter architecture is designed and tested. The experimental results show a rejection band centered at 97 GHz and a rejection level of 16 dB. Second, a dual-band amplifier is demonstrated with flexible frequency ratios. The proposed amplifier features novel dual-band Wilkinson power divider/combiner that allows large frequency ratios between the first and second bands (2.16 to 4.9) between the first and second operating frequencies. The stand-alone combiner has maximum potential combining efficiency of 95% and 75% at the first and second frequency bands, respectively. A 2.4 / 5.8 GHz prototype amplifier is tested to verify its dual-band functionality. Measured linear gains are 12.85 dB and 11.09 dB at the first and second frequency bands, respectively. Third, a “spatial” combiner inspired power combiner / divider for solid-state amplifier application is presented. The proposed “one-stage” combining is realized by a single port tapered to an oversized microstrip connecting to parallel multiport microstrip sections. Uniform amplitude/phase and complex impedance matching at the parallel multiport microstrips are simultaneously achieved by adjusting the geometry of the structure. A prototype 5 GHz 1-to-4 divider/combiner designed using ADS co-simulation is characterized. The measured combining efficiency of 82.4% is achieved at 5 GHz. Lastly, a nanostructure thin film with giant dielectric response is proposed by strategically dispersing silver nano-particles inside a Tropropylene glycol diacrylate (TRPGDA) polymer. The dielectric properties of the proposed thin film are experimentally extracted at the microwave frequencies. The measurement sample is prepared by laying a coplanar waveguide (CPW) line on the thin film that is supported by a glass substrate. Two-port S-parameter measurements on the CPW are performed. Dispersion mechanism due to internal inductance of the CPW line when calculating the effective dielectric constant is investigated. The extraction involves conformal mapping approximation that uses closed-form equations to calculate the dielectric constant and the loss tangent of each layer based on the effective dielectric constant and loss tangent of the entire structure. Alternatively, direct fitting technique using simulation to model the experiment is studied. The results of the two techniques are compared and discussed. The measured dielectric constant ranges from 30000 to 4600 from 1 to 20 GHz with a loss tangent of 0.55 to 1.75 from 1 to 20 GHz.

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Wakatsuchi, Hiroki. "Computational studies of the electromagnetic properties of metamaterials and applications." Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/12146/.

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In this thesis computational studies on electromagnetic properties of metamaterials and applications are introduced. The studies include an introduction to the time-domain transmission line modelling (TLM) method and the fundamental scattering properties of metamaterials. The first major objective of the thesis is directed to predicting the resonant frequencies of some forms of cut-wire (CW) metamaterials by using approximate equivalent circuits. The second objective is the improvement of metamaterial simulation efficiency based on two approaches: a simulation method based on retrieved metamaterial electromagnetic properties and one based on digital filtering (DF) techniques. By using the DF techniques, metamaterials are effectively modelled and the simulation times are significantly reduced. The third objective is focused on studying CW metamaterial as potential absorbers by deliberately including conductive losses. The proposed CW metamaterials are found to exhibit customisable absorptance characteristics with arbitrary polarisation. This metamaterial absorber study includes an experimental validation.

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Meduri, Kavita. "Carbon-Supported Transition Metal Nanoparticles for Catalytic and Electromagnetic Applications." Thesis, Portland State University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10933285.

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Recently, there has been growing interest in using transition metals (TM) for catalytic and electromagnetic applications, due to the ability of TMs to form stable compounds in multiple oxidation states. In this research, the focus has been on the synthesis and characterization of carbon-supported TM nanoparticles (NPs), specifically palladium (Pd) and gold (Au) NPs, for catalytic applications, and transition metal oxides (TMO) NPs, specifically Fe₃O₄ NPs for electromagnetic applications. Carbon supports have several advantages, such as enabling even distribution of particles, offering large specific surface area with excellent electron conductivity, and relative chemical inertness.

In this dissertation, for catalytic applications, emphasis was on removal of trichloroethylene (TCE) from groundwater. For this application, carbon-supported Pd/Au NP catalysts were developed. Pd was chosen because it is more active, stable and selective for desired end-products, and Au has shown to be a good promotor of Pd’s catalytic activity. Often, commercially available Pd-based catalysts are made using harsh chemicals, which can be harmful to the environment. Here, an environmentally friendly process with aspects of green chemistry was developed to produce carbon-supported Pd/Au NP catalysts. This process uses a combination of sonochemistry and solvothermal syntheses. The carefully designed carbon-supported Pd/Au NP catalyst material was systematically characterized, tested against TCE, and optimized for increased rate of removal of TCE. Electron microscopy and spectroscopy techniques were used to study the material including structure, configuration and oxidative state. The Pd/Au NPs were found mainly to form clusters with an aggregate-Pd_ShellAu_Core structure. Using state-of-the-art direct detection with electron energy loss spectroscopy, the Pd NPs were found to have an oxidative state of zero (0). The formation of the catalyst material was studied in detail by varying several synthesis parameters including type of solvent, sonication time, synthesis temperature etc. The most optimized catalyst was found remove TCE at double the rate of corresponding commercial Pd-based catalysts in a hydrogen headspace. This material was found to catalyze the removal of TCE via traditional hydrodehalogenation and shows promise for the removal of other contaminants such as trichloropropane (TCP), carbon tetrachloride (CT).

This green approach to make and optimize TM materials for specific applications was extended to TMOs, specifically magnetite (Fe₃O₄) and further developed for the application of electromagnetism. As catalysts, Fe₃O₄ is used for removal of p-nitrophenol from water. However, since the carbon-supported Pd/Au material system was developed and optimized for catalysis, here, carbon-supported Fe₃O₄ NPs were developed for electromagnetic applications. There has been growing interest in tuning the magnetic properties of materials at room temperature with the use of external electric fields, for long-term applications in data storage and spintronic devices. While a complete reversible change of material properties has not yet been achieved, some success in partial switching has been achieved using multiferroic spinel structures such as Fe₃O₄. These materials experience a change in magnetic moment at room temperature when exposed to the electric fields generated by electrochemical cells such as lithium ion batteries (LIBs) and supercapacitors (SC). In the past, a 1% reversible change was observed in Fe₃O₄ using LIBs. Here, building on the developments from previous material system, Fe₃O₄ NPs were directly hybridized onto the graphene support in order to increase the observable change in magnetic moment. The material was systematically designed and tested for this application, including a study of the material formation. A simple, environmentally friendly synthesis using the solvothermal process was implemented to make the graphene-supported Fe₃O₄ NPs. This new material was found to produce a reversible change of up to 18% in a LIB. In order to overcome some of the difficulties of testing with a LIB, a corresponding hybrid SC was designed, built and calibrated. The graphene-supported Fe₃O₄ NPs were found to produce a net 2% reversibility in the SC, which has not been reported before. The results from both the LIB and SC were analyzed to better understand the mechanism of switching in a spinel ferrite such as Fe₃O₄, which can help optimize the material for future applications.

The focus of this dissertation was on the development of a methodology for carbon-supported TM and TMO NPs for specific applications. It is envisioned that this approach and strategy will contribute towards the future optimization of similar material systems for a multitude of applications.

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Carbonell, Olivares Jorge. "Electromagnetic analysis of active and passive devices for space applications." Lille 1, 1998. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/1998/50376-1998-69.pdf.

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Les progres recents en nanotechnologie, caracterisation haute frequence and conception assistee par ordinateur ont modifie de maniere importante la fabrication de systemes aux frequences millimetriques et sub-millimetriques. Dans ce contexte, ce travail concerne la simulation electromagnetique de composants actifs et passifs pour des applications spatiales. Trois sujets en relation avec le domaine terahertz, (i) un multiplicateur de frequence employant une heterostructure barriere varactor (hbv), (ii) des microinterrupteurs et lignes de transmission micro-usinees et (iii) des structures a bande interdite photonique metalliques, ont ete specialement etudies. En ce qui concerne la conception du multiplicateur de frequence, de 83 a 250 ghz, notre contribution est basee sur l'analyse electromagnetique du composant actif en tenant compte de son environnement. En partant d'un composant hbv fabrique a l'iemn avec de bonnes performances en termes de rapport de capacite 5:1 et de niveau de capacite sans polarisation, 1 ff/m#2, nous avons etudie l'influence des techniques d'integration sur ses performances
En combinant differentes approches, telles que des techniques de mesure sous pointes, des simulations en equilibrage harmonique et une analyse electromagnetique, nous avons pu analyser un composant integre dans une cellule de multiplication. Par rapport aux composants micro-usines, nous nous sommes interesses, d'une part, a des lignes coplanaires sur membrane, et d'autre part a des microinterrupteurs. Un comportement faibles pertes sans dispersion a ete demontre dans le premier cas jusqu'a 100 ghz, alors que l'on a determine des frequences d'utilisation maximales dans le deuxieme cas. Finalement, notre effort s'est oriente vers l'analyse de structures metalliques periodiques artificielles presentant des bandes interdites electromagnetiques. Ces materiaux a bande interdite photonique sont potentiellement interessants pour des applications millimetriques telles que filtres, elements rayonnants ou de guidage

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30

Wilson, Michelle Lynn. "Design and Fabrication of an Electromagnetic Probe for Biomedical Applications." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1313509778.

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31

O'Donnell, Andrew Nickerson. "Sparsity and Compressed Sensing for Electromagnetic Scattering and Radiation Applications." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1397480914.

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32

Haji, Akbari Fini Siavash. "Theory and simulation of electromagnetic dampers for earthquake engineering applications." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/57068.

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The present study develops applications of electromagnetic devices in Civil Engineering. Three different types of electromagnetic system are investigated through mathematical and numerical models. Chapter 3 deals with Coil-Based Electromagnetic Damper (CBED). CBEDs can operate as passive, semi-active and active systems. They can also be considered as energy harvesting systems. However, results show that CBEDs cannot simultaneously perform as an energy harvesting and vibration control system. In order to assess the maximum capacity of CBEDs, an optimization is conducted. Results show that CBEDs can produce high damping density only when they are considered as a passive vibration control system. Chapter 4 deals with the development of a novel Eddy Current Damper (ECD). The eddy current damper uses permanent magnets arranged in a circular manner to create a strong magnetic field, where specially shaped conductive plates are placed between the permanent magnets to cut through the magnetic fields. Detailed analytical equations are derived and verified using the finite element analysis program Flux. The verified analytical models are used to optimize the damper design to reach the maximum damping capacity. The analytical simulation shows that the proposed eddy current damper can provide a high damping density up to 2,733 kN-s/m⁴. The Hybrid Electromagnetic Damper (HEMD) are developed and designed in Chapter 5. The idea is to couple the CBED and ECD with the aim of designing a semi-active, active and energy harvesting electromagnetic damper. The simulation results show that it is feasible to manufacture hybrid electromagnetic dampers for industrial applications.
Applied Science, Faculty of
Civil Engineering, Department of
Graduate

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33

Jennings, Paul Anthony. "New applications of statistics within automotive EMC and pass-by noise." Thesis, University of Warwick, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343798.

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Heß, Martin Verfasser], and Peter [Akademischer Betreuer] [Benner. "Reduced basis approximations for electromagnetic applications / Martin Heß ; Betreuer: Peter Benner." Magdeburg : Universitätsbibliothek, 2016. http://d-nb.info/1113687223/34.

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35

Smith, Graeme C. "Multi-dimensional tunnelling in regular systems, with applications to electromagnetic problems." Thesis, University of Nottingham, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.428933.

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36

Noetscher, Gregory Michael. "The VHP-F Computational Phantom and its Applications for Electromagnetic Simulations." Digital WPI, 2014. https://digitalcommons.wpi.edu/etd-dissertations/237.

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Modeling of the electromagnetic, structural, thermal, or acoustic response of the human body to various external and internal stimuli is limited by the availability of anatomically accurate and numerically efficient computational models. The models currently approved for use are generally of proprietary or fixed format, preventing new model construction or customization. 1. This dissertation develops a new Visible Human Project - Female (VHP-F) computational phantom, constructed via segmentation of anatomical cryosection images taken in the axial plane of the human body. Its unique property is superior resolution on human head. In its current form, the VHP-F model contains 33 separate objects describing a variety of human tissues within the head and torso. Each obejct is a non-intersecting 2-manifold model composed of contiguous surface triangular elements making the VHP-F model compatible with major commercial and academic numerical simulators employing the Finite Element Method (FEM), Boundary Element Method (BEM), Finite Volume Method (FVM), and Finite-Difference Time-Domain (FDTD) Method. 2. This dissertation develops a new workflow used to construct the VHP-F model that may be utilized to build accessible custom models from any medical image data source. The workflow is customizable and flexible, enabling the creation of standard and parametrically varying models facilitating research on impacts associated with fluctuation of body characteristics (for example, skin thickness) and dynamic processes such as fluid pulsation. 3. This dissertation identifies, enables, and quantifies three new specific computational bioelectromagnetic problems, each of which is solved with the help of the developed VHP-F model: I. Transcranial Direct Current Stimulation (tDCS) of human brain motor cortex with extracephalic versus cephalic electrodes; II. RF channel characterization within cerebral cortex with novel small on-body directional antennas; III. Body Area Network (BAN) characterization and RF localization within the human body using the FDTD method and small antenna models with coincident phase centers. Each of those problems has been (or will be) the subject of a separate dedicated MS thesis.

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37

Ao, Chi On 1970. "Electromagnetic wave scattering by discrete random media with remote sensing applications." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/16782.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2001.
Includes bibliographical references (p. 171-182).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
The scattering of electromagnetic waves in medium with randomly distributed discrete scatterers is studied. Analytical and numerical solutions to several problems with implications for the active and passive remote sensing of the Earth environment are obtained. The quasi-magnetostatic (QMS) solution for a conducting and permeable spheroid under arbitrary excitation is presented. The spheroid is surrounded by a weakly conducting background medium. The magnetic field inside the spheroid satisfies the vector wave equation, while the magnetic field outside can be expressed as the gradient of the Laplace solution. We solve this problem exactly using the separation of variables method in spheroidal coordinates by expanding the internal field in terms of vector spheroidal wavefunctions. The exact formulation works well for low to moderate frequencies; however, the solution breaks down at high frequency due to numerical difficulty in computing the spheroidal wavefunctions. To circumvent this difficulty, an approximate theory known as the small penetration-depth approximation (SPA) is developed. The SPA relates the internal field in terms of the external field by making use of the fact that at high frequency, the external field can only penetrate slightly into a thin skin layer below the surface of the spheroid. For spheroids with general permeability, the SPA works well at high frequency and complements the exact formulation. However, for high permeability, the SPA is found to give accurate broadband results. By neglecting mutual interactions, the QMS frequency response from a collection of conducting and permeable spheroids is also studied.
(cont.) In a dense medium, the failure to properly take into account of multiple scattering effects could lead to significant errors. This has been demonstrated in the past from extensive theoretical, numerical, and experimental studies of electromagnetic wave scattering by densely packed dielectric spheres. Here, electromagnetic wave scattering by dense packed dielectric spheroids is studied both numerically through Monte Carlo simulations and analytically through the quasi-crystalline approximation (QCA) and QCA with coherent potential (QCA-CP). We assume that the spheroids are electrically small so that single-particle scattering is simple. In the numerical simulations, the Metropolis shuffling method is used to generate realizations of configurations for non-interpenetrable spheroids. The multiple scattering problem is formulated with the volume integral equation and solved using the method of moments with electrostatic basis functions. General expressions for the self-interaction elements are obtained using the low-frequency expansion of the dyadic Green's function, and radiative correction terms are included. Results of scattering coefficient, absorption coefficient, and scattering matrix for spheroids in random and aligned orientation configurations are presented. It is shown that independent scattering approximation can give grossly incorrect results when the fractional volume of the spheroids is appreciable.
(cont.) In the analytical approach, only spheroids in the aligned configuration are solved. Low-frequency QCA and QCA-CP solutions are obtained for the average Green's function and the effective permittivity tensor. For QCA-CP, the low-frequency expansion of the uniaxial dyadic Green's function is required. The real parts of the effective permittivities from QCA and QCA-CP are compared with the Maxwell-Garnett mixing formula. ...
by Chi On Ao.
Ph.D.

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Akerson, Jerome Jeffrey 1961. "Numerical techniques for electromagnetic applications in microelectronic and radar imaging systems." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/46116.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.
Includes bibliographical references (p. 227-242).
by Jerome J. Akerson.
Ph.D.

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39

Nolan, William Rane. "Electrically insulating phosphate coatings for iron powder based electromagnetic core applications." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/54521.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 24).
Powdered metals, such as iron, are a common building block for electromagnetic cores. An iron powder was reacted with phosphoric acid to create a layer of iron phosphate on each particle. This electrically insulating phosphate layer could lead to significant reductions in eddy current losses in alternating current applications. The electro-magnetic properties of this phosphate-coated powder material were examined as a function of heat treatment. Additionally, SEM and EDS were used analyze the particle interfaces and composition in compressed bar-shape samples that were heat treated at temperatures ranging from 315°C to 5400°C. The bulk composition of oxygen and phosphorus are also tested for each heat treatment. Results indicate that after high temperature heat treatments (required for stress reduction, sintering, increased magnetic permeability, and decreased coercivity), the bulk resistivity is reduced. Correlation of interface structure and composition with these trends in resistivity is discussed. Ultimately, this analysis will aid in the development of coatings that withstand higher temperatures and yield ideal properties for electromagnetic core applications.
by William Rane Nolan.
S.B.

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40

Palreddy, Sandeep R. "Wideband Electromagnetic Band Gap (EBG) Structures, Analysis and Applications to Antennas." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/54004.

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In broadband antenna applications, the antenna's cavity is usually loaded with absorbers to eliminate the backward radiation, but in doing so the radiation efficiency of the antenna is decreased. To enhance the radiation efficiency of the antennas EBG structures are used, but they operate over a narrow band. Uniform electromagnetic band gap (EBG) structures are usually periodic structures consisting of metal patches that are separated by small gaps and vias that connect the patches to the ground plane. The electrical equivalent circuit consists of a resonant tank circuit, whose capacitance is represented by the gap between the patches and inductance represented by the via. EBG structures are equivalent to a magnetic surface at the frequency of resonance and thus have very high surface impedance; this makes the EBG structures useful when mounting an antenna close to conducting ground plane, provided the antenna's currents are parallel to the EBG structure. Because EBG structures are known to operate over a very narrow band, they are not useful when used with a broadband antenna. Mushroom-like uniform EBG structures (that use vias) are compact in size have low loss, can be integrated into an antenna to minimize coupling effects of ground planes and increase radiation efficiency of the antenna. The bandwidth of an EBG structure is defined as the band where the reflection-phase from the structure is between +900 to -900. In this dissertation analysis of EBG structures is established using circuit analysis and transmission line analysis. Methods of increasing the bandwidth of EBG structures are explored, by cascading uniform EBG structures of different sizes progressively and vertically (stacked), and applications with different types of antennas are presented. Analyses in this dissertation are compared with previously published results and with simulated results using 3D electromagnetic tools. Validation of applications with antennas is carried by manufacturing prototypes and comparing measured performance with analysis and 3D electromagnetic simulations. The improvements in performance by using wideband progressive EBG and wideband stacked EBG structures are noted.
Ph. D.

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41

Karisan, Yasir. "Full-wave Electromagnetic Modeling of Electronic Device Parasitics for Terahertz Applications." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1419019102.

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42

Chen, Yi. "Propagation and Excitation of Electromagnetic Modes for Travelling-wave MRI Applications." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1449158025.

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43

Wildman, Raymond A. "Geometry optimization and computational electromagnetics methods and applications /." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 191 p, 2008. http://proquest.umi.com/pqdweb?did=1481670101&sid=23&Fmt=2&clientId=8331&RQT=309&VName=PQD.

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44

Altuntas, Emre. "Forecasting Of The Electromagnetic Waves In Ionized Media Related To Aerospace Applications." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608781/index.pdf.

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The dominant natural electromagnetic (EM) radiation in the extremely low frequency (ELF) range is due to global lightning activity. Radio waves of ELF band traveling along the surface of the ground are able to circle the globe and return to the starting point. Schumann Resonances (SR) are the EM phenomena which occur in the cavity formed by the conducting Earth and the ionosphere, with peak frequencies close to 8, 14, 20, 26 Hz, etc. The spectral characteristics of the SR modes are defined by their resonant mode amplitudes, center frequencies and half-widths. The characteristics of the SR became important in aerospace, marine applications, atmospheric studies, in addition to their relevance to global lightning studies due to their frequency band. The objective of this work is two fold: (i) to investigate the characteristics of SR parameters obtained at Sarkoy in Turkey
(ii) to model the nonlinear characteristics of the Near Earth Space Processes by forecasting the 1st SR mode intensities different time steps in advance using neural network modeling approach. The results show that the SR amplitudes exhibit the characteristics of Tropical African lightning activity and have maxima around 1400 UT. The neural network results show that the proposed model is able to forecast SR amplitudes from 0,5 to 36 hours in advance within reasonable error limits. Furthermore, a fuzzy neural network model with a non&ndash
linear optimization algorithm for the training phase is proposed and tested for the future work.

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Lundbäck, Jonas. "On signal processing and electromagnetic modelling : applications in antennas and transmission lines /." Karlskrona : Department of Signal Processing, School of Engineering, Blekinge Institute of Technology, 2007. http://www.bth.se/fou/Forskinfo.nsf/allfirst2/62a51cd9a6f3d716c12572c1003f0063?OpenDocument.

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46

Chen, Chi-Chih. "Design and applications of two low frequency guided wave electromagnetic measurement structures." The Ohio State University, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=osu1406708013.

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47

Lundbäck, Jonas. "On signal processing and electromagnetic modelling : applications in antennas and transmission lines." Doctoral thesis, Ronneby : Blekinge Institute of Technology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-00363.

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This doctoral thesis is comprised of five parts. The first three parts concern signal processing and electromagnetic modelling of multiport antennas. The last two parts concern signal processing and transmission line theory applied to wave splitting on transmission lines. In Part I, the spherical vector wave expansion of the electromagnetic field is used to completely characterize a multiport antenna. A general framework for modelling an antenna configuration based on measurement data and numerical computation is obtained. The generic electromagnetic model for arbitrary multiport antennas or vector sensors is applied in direction of arrival (DOA) estimation. Next, in Part II using the generic electromagnetic model (from Part I), we obtain the Cramér–Rao bound (CRB) for DOA and polarization estimation using arbitrary multiport antennas. In the Gaussian case, the CRB is given in terms of the transmission matrix, the spherical vector harmonics and its spatial derivatives. Numerical examples using an ideal Tripole antenna array and a non-ideal Tetrahedron antenna array are included. In Part III, the theory of optimal experiments is applied to a cylindrical antenna near-field measurement setup. The D-optimal (determinant) formulation using the Fisher information matrix of the multipole coefficients in the spherical wave expansion of the electrical field result in the optimal measurement positions. The estimation of the multipole coefficients and corresponding electric field using the optimal measurement points is studied using numerical examples and singular value analysis. Further, Part IV describes a Digital Directional Coupler (DDC), a device for wave splitting on a transmission line. The DDC is a frequency domain digital wave splitter based on two independent wide-band measurements of the voltage and the current. A calibration of the digital processor is included to account for the particular transmission line and the sensors that are employed. Properties of the DDC are analyzed using the CRB and an experiment where wave splitting was conducted on a coaxial–cable is accounted for. Finally, in Part V the DDC has been designed and implemented for wave splitting on a medium voltage power cable in a power distribution station using low cost wide–band sensors. Partial discharge measurements are conducted on cross–linked polyethylene insulated power cables. The directional separation capabilities of the DDC are visualized and utilized to separate multiple reflections from partial discharges based on the direction of travel.

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Mohamed, Adel K. "Applications of magnetotelluric and transient electromagnetic methods in groundwater and engineering studies." Thesis, University of Leicester, 2002. http://hdl.handle.net/2381/30449.

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The main aim of this study is to use the transient electromagnetic (TEM) and magnetotelluric (MT) methods to determine the electrical resistivity distribution of the subsurface and locate possible structural features controlling groundwater distribution in the northern and south-eastern margins of Parnaiba basin, Brazil. MT data from 24 stations along two profiles across the margins of the basin have been processed using standard tensorial techniques to obtain the interpretable response functions. The TEM data recorded at the same sites facilitated the removal of static shift and the recovery of the near-surface structure. One-dimensional (1-D) joint inversion of TEM and MT data yielded an approximate geoelectric structure for each profile. Subsequent two-dimensional (2-D) modelling revealed a more realistic resistivity distribution for each profile. The result of 2-D regularized inversion of MT data delineated the main sedimentary sequences and deep basement features. A resistive crystalline basement (â‰¥ 200 &OHgr;m) is overlain by relatively conductive sedimentary sequences of varying resistivities and thicknesses. The existence of a major basement trough at the expected position of a concealed fault in the north-eastern margin of the basin was proved by the MT model. This anomalous zone is interpreted to have a thick development of granular sediments and may be a good site for groundwater development. The 2-D model for the south-eastern profile defined the position of a major fault, which is interpreted as Picos fault and may have implication for groundwater development. A graben-like structure is also suggested âˆ¼10 km further east from Picos fault and considered to be a good target for groundwater development. Overall, the 2-D MT inversion results are consistent with the available geological information and offer new insights into the deep structure of the basin margins of Parnaiba basin.

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Rojanapornpun, Olarn Electrical Engineering &amp Telecommunications Faculty of Engineering UNSW. "Microfabrication technology for an integrated monolithic electromagnetic microactuator based on polymer bonded permanent magnet." Awarded by:University of New South Wales. School of Electrical Engineering and Telecommunications, 2006. http://handle.unsw.edu.au/1959.4/27014.

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Electromagnetic microactuators with permanent magnets have many potential applications such as micro-energy scavengers, microswitches, micromirrors and microfluidics. However, many electromagnetic microactuator designs utilize either external permanent magnet or external coil, which do not allow tight integration to other MEMS components and further miniaturization. Furthermore, all of the available permanent magnet microfabrication technologies have some drawbacks and improvements are required. Thus the integrated monolithic electromagnetic microactuator is investigated in this project. The three main components of the electromagnetic actuator have been investigated separately. A novel microfabrication technology called ???Template printing???for the fabrication of polymer bonded permanent magnet has been investigated and developed. It is based on ???Screen printing??? which has its drawbacks on alignment accuracy and poor line definition. This is eliminated in ???Template printing??? by photolithography of the photoresist template. The shape and location of the permanent magnet is defined by the template. A new approach based on the filling of dry magnetic powder and vacuum impregnation has been developed to form the polymer bonded permanent magnet. This allows the use of short pot-life matrix material and the elimination of homogenous mixing. A monolithic electromagnetic microactuator has been fabricated successfully. It consists of a 2-layer planar copper microcoil, surface micromachined polyimide beam and Strontium ferrite/EPOFIX permanent magnet (diameter of 460 ??m and 30 ??m thickness). Large deflection in excess of 100 ??m at 35 mA driving current and magnetic force of 0.39 ??N/mA have been achieved. It compares favourably with other much larger electromagnetic actuators that have been reported. ???Template printing??? has the potential of being a low temperature batch process for the microfabrication of thick polymer bonded permanent magnets with high magnetic properties and low residual stress. The fabrication consistency and the quality of template printed magnet can be improved in future studies.

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Sustersic, Nathan Anthony. "The growth and characterization of silicon-germanium devices for optoelectronic applications." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 3.10 Mb., 83 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:1435828.

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Dissertations / Theses on the topic 'Electromagnetic applications'

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