Dissertations / Theses: 'Electromagnetical systems'

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Yao, Shun. "Origami Reconfigurable Electromagnetic Systems." FIU Digital Commons, 2017. https://digitalcommons.fiu.edu/etd/3514.

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With the ever-increasing demand for wireless communications, there is a great need for efficient designs of electromagnetic systems. Reconfigurable electromagnetic systems are very useful because such designs can provide multi-functionality and support different services. The geometrical topology of an electromagnetic element is very important as it determines the element’s RF performance characteristics. Origami geometries have significant advantages for launch-and-carry electromagnetic devices where devices need to fold in order to miniaturize their size during launch and unfold in order to operate after the platform has reached orbit. This dissertation demonstrates a practical process for designing reconfigurable electromagnetic devices using origami structures. Four different origami structures are studied and the integrated Mathematical-Computational-Electromagnetic models of origami antennas, origami reflectors and origami antenna arrays are developed and analyzed. These devices provide many unique capabilities compared with the traditional designs, such as band-switching, frequency tuning, polarization adjustment and mode reconfigurability. Prototypes are also manufactured to validate the performances of the designs. These designs change their geometry naturally, and they can be compactly packaged into small volume, which make them very suitable for spaceborne and satellite communication. Origami antennas and origami electromagnetics are expected to impact a variety of applications related to communications, surveillance and sensing.

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Thierauf, Rainer Georg. "A Lagrangian for a system of two dyons." PDXScholar, 1988. https://pdxscholar.library.pdx.edu/open_access_etds/3840.

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Maxwell's equations for the electromagnetic field are symmetrized by introducing magnetic charges into the formalism of electrodynamics. The symmetrized equations are solved for the fields and potentials of point particles. Those potentials, some of which are found to be singular along a line, are used to formulate the Lagrangian for a system of two dyons (particles with both electric and magnetic charge). The equations of motion are derived from the Lagrangian. It is shown that the dimensionality constants k and k * , which we r e introduced to define the units of the electromagnetic fields, have to be equal in order to avoid center of mass acceleration in the two dyon system.

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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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Davis, Aaron Charles, and aaron davis@rmit edu au. "Quantitative Characterisation of Airborne Electromagnetic Systems." RMIT University. Applied Physics, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080723.103030.

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I address the geometric problem of the pendulum-like swinging of towed birds for AEM platforms. I establish a link between actual observed bird swing and its effect on survey data for two different systems and explain the link by a model that compares actual survey data to the calculated mutual inductance coupling of a dipole pair over an infinitely conductive half space, which pair is permitted arbitrary pitch, roll and altitude changes. I develop a non-linear filter that removes bird swing effects from survey data which successfully corrected data from 3 different AEM surveys. Calibration of several different time domain AEM systems is attempted using an accurately laid out and surveyed, closed, multi-turn loop of known resistance and self-inductance that is placed on - but insulated from - resistive ground. I derive a rigourous mathematical model that predicts airborne receiver's response to the coupling to the transmitter current waveform and total system geometry. The method was proven to be successful over resistive ground, with significant system problems identified such as: altimetry error, spatial averaging of data during postprocessing, error in the predicted horizontal position of the AEM platform, receiver windowing and timing errors and bird swing. I show that, although we can calibrate a time domain AEM system for a single flyover, it is impossible to calibrate an AEM system for geometry. As an intermediate step in the calibration process, I show that by monitoring the current induced in the ground loop we can obtain the waveform of the AEM transmitter current throu gh deconvolution in the Fourier domain. Simple and cost effective methods for the improvement of quantitative AEM data are presented in this thesis. However, until the geometry problem of AEM platforms is solved, full system calibration will not be obtained and filters will need to be applied to the data. I recommend the use of: GPS antennas mounted on all towed birds, able to be post-processed for accurate position recovery, reliable bird-mounted scanning altimeters that do not rely on range-finding technology but instead employ a shortest path algorithm, pitch and roll sensors mounted on the trailed bird and the measurement of airspeed of both the towed bird and the aircraft during surveys.

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Enohnyaket, Mathias. "Electromagnetic characterization of power electronic systems." Doctoral thesis, Luleå tekniska universitet, EISLAB, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-17800.

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Propelled by increased global awareness and demand for clean energy systems, there is a growing trend in transportation, utility, industrial, and residential applications towards the utilisation of power electronic systems with enhanced power ow controllability and eciency. Examples of power electronics applications include terminal converters in high-voltage direct Current (HVDC) transmission; exible AC transmission systems (FACTS); and converters to interface alternative energy systems such as wind turbines to the grid, variable-speed motor drives in pump systems, vehicular propulsion systems, air-conditioners, and refrigerators.The basic functionality of power electronic components is achieved by switching high voltages and currents. Recent advancements in semiconductor technology have significantly improved the current and voltage handling capabilities and the switching frequencies of power electronic devices. However, this rapid switching of high currents and voltages in turn generates electromagnetic disturbances that could distort the functionality of the power electronic equipment and other devices in the vicinity. Electromagnetic compatibility (EMC) regulations and functionality requirements impose restrictions on the design of power electronic systems. To design robust power electronic systems, a thorough understanding of the related electromagnetic issues is required.This thesis focuses on the EMC characterisation of power electronic systems and contains two major phases.In the first phase, the high frequency characterisation of air-core reactors was considered. Air-core reactors are typically used in power systems for current limiting, ltering, shunting, and neutral grounding applications. It is of interest to understand the behaviour of air-core reactors in the presence of high frequency signals, especially from switching operations in the power electronic components. Using the partial element equivalent circuit (PEEC) approach, air-core reactor models, helpful in design and electromagnetic analysis, were created. The PEEC models were able to predict the current and voltage distributions and the eventual electromagnetic emissions at different frequencies. The second phase involved the characterisation of electromagnetic emissions from PWM drives using both modeling and measurement. A case study was performed on a prototype hybrid electric vehicle (HEV). Typically, emissions from PWM drives are expected at harmonics of the PWM switching frequency (fc) and harmonics of the fundamental frequency (f0) of the phase voltages. In this study, it was established that space vector PWM drives generate low-frequency pulsating (LFP) emissions at a frequency of 6f0. The switching of voltage vectors generates common mode current spikes because of the presence of stray capacitances and inductances. The spikes superpose across sector boundaries, forming spikes of double or triple amplitude that constitute the LFP emissions. The amplitudes of these ulsations were shown to be dependent on the drive parameters, such as the load, the speed, and the voltage slew rates. These common mode emissions enhance the emissions at harmonics of the switching frequency, create low-frequency emissions, and when injected into an electric motor, could cause torque pulsations and speed uctuations that may degrade drive functionality. Measurements from an HEV prototype show the LFP emissions, and theoretical models were developed to characterise them.

Godkänd; 2010; 20100826 (mathen); DISPUTATION Ämnesområde: Industriell elektronik/Industrial Electronics Opponent: Professor Mats Alaküla, Lund University and Volvo Car AB Ordförande: Professor Jerker Delsing, Luleå tekniska universitet Tid: Torsdag den 30 september 2010, kl 09.30 Plats: A1514 Demostudion, Luleå tekniska universitet

EM Karaktärisering och Modellering av Elektriska Hybriddrivsystem

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Lim, Chan-Ping Edwin. "Computational electromagnetic modeling for wireless channel characterization." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1158607443.

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Huang, Yi. "The investigation of chambers for electromagnetic systems." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359474.

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Sakaguchi, Aya S. M. Massachusetts Institute of Technology. "Micro-electromagnetic formation flight of satellite systems." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/39708.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, June 2007.
Includes bibliographical references (p. 93-94).
Electromagnetic formation flight (EMFF) investigates the concept of using electromagnets to provide the forces to maintain a satellite's relative position in a formation. Thus far, high temperature superconducting (HTS) wire has been considered the enabling technology and the concept has been sized for aggressive maneuvering over large distances with concepts such as terrestrial planet finder in mind. A nominal mode of operation, of simply keeping a fleet of satellites within a volume, calls for a simpler system. Micro-EMFF (pEMFF) investigates the use of conventional conductors, capacitors and solar cells for use on formations at small separation distances and requiring small forces. Simple one-dimensional models investigate this concept and the optimal mass implementations are compared to traditional propulsion systems as well as HTS EMFF and shown to be advantageous in close proximity formations. Because the forces involved with pEMFF are so small, a mobile-like device was built to validate the simple models and to allow for the further investigation of control algorithms. Overall, this thesis proves the viability of the pEMFF concept in close proximity, small force requiring formations.
by Aya Sakaguchi.
S.M.

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Luo, Chiyan 1979. "Anomalous photon phenomena in electromagnetic crystal systems." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/29451.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2004.
Includes bibliographical references (p. 141-151).
In 2000, a composite material was fabricated in the gigahertz range that appeared to exhibit simultaneously negative values of permittivity and permeability. Such substances were known as "left-handed materials," and had been predicted to enable a variety of anomalous electromagnetic effects. Intense interests have developed in these materials after microwave negative refraction was experimentally observed in 2001. During the same period, a series of experiments was carried out reporting remark- able optical refraction phenomena in periodically modulated dielectric structures. A super-sensitive dependence on incidence parameters called "the superprism effect" was observed and interpreted using the anomalous group velocities in these structures. Negative refractive indices were also demonstrated and explained in terms of the backward-wave effects. Through theoretical and computational means, this research studies anomalous light phenomena in electromagnetic crystals. First, negative refraction of light is shown to be possible inside two-dimensional structures without requiring the backward- wave condition. The analysis is then extended to three-dimensional systems to predict a crystal enabling negative refraction for all incident directions. Second, transmission of evanescent waves through electromagnetic-crystal slabs is studied, and a general result is established linking bound slab resonance states to an amplification effect of evanescent waves.
(cont.) This theory is then combined with negative refraction to study the Veselago-Pendry superlensing effect, and a subwavelength focusing effect beating the classical diffraction limit is found. Third, it is proposed that the superprism effect may occur based purely on phase velocities. This effect can produce a magnitude of dispersion similar to that based on group velocities, making beam-steering possible in free space. Fourth, the analysis of light propagation is applied to the radiation from charged particles traveling through electromagnetic crystals. It is found that when coupled with Smith-Purcell radiation, Cherenkov radiation can occur with a reversed direction of propagation or a reversed radiation cone. Fifth, a model is constructed to simulate the thermal radiation from photonic crystals directly. Electromagnetic crystals are found to bring significant enhancement to the emissivity, with potential applications in thermal photovoltaic and incandescent lighting sources.
by Chiyan Luo.
Ph.D.

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Tassoudji, Mohammad Ali. "Electromagnetic interference in electronic circuits and systems." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/35392.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1994.
Includes bibliographical references (p. 191-198).
by Mohammad Ali Tassoudji.
Ph.D.

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

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Foo, Jong Teck. "Selection of controller gains for an electromagnetic suspension system." Ohio : Ohio University, 1993. http://www.ohiolink.edu/etd/view.cgi?ohiou1175287253.

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Chilaka, Venkata Sailaja Riggs Lloyd Stephen. "Electromagnetic induction systems for discrimination among metallic targets." Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Spring/doctoral/CHILAKA_SAILAJA_59.pdf.

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

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Cairns-McFeeters, Eugenia L. "Effects of surface-based ducts on electromagnetic systems." Thesis, Monterey, California : Naval Postgraduate School, 1992. http://handle.dtic.mil/100.2/ADA257443.

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Thesis (M.S. in Systems Engineering (Electronic Warfare)--Naval Postgraduate School, September 1992.
Thesis Advisor: Davidson, Kenneth L. "September, 1992." Description based on title screen as viewed on March 18, 2009. Includes bibliographical references (p. 120-121). Also available in print.

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Shepherd, Nolan Miller. "Manipulating Electromagnetic Fields in Colloidal Metal Nanoparticle Systems." Thesis, The University of Chicago, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=10977604.

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Colloidal metal nanoparticles are renowned for their ability to strongly scatter and absorb light due to size- and environment-dependent plasmon modes. Active areas of research focus on using both single and collections of nanoparticles to control the shape of electromagnetic fields on the nanoscale. The excitation of plasmon modes in the nanoparticles confines the energy from incident fields to sub-wavelength scales with distributions controlled by the morphology of the particles, and multiple particles arranged in the near-field can extend the excitation into a collective mode. The excitation of plasmon modes can create enhancements of the field intensity, which have been leveraged for enhancing radiative rates of light-emitting particles and molecules and increasing molecular sensing signals. However, many of these applications rely on electric field enhancements in the near field and using static nanoparticle arrangements. We present extensions to this paradigm, first by exploring the excitation of collective plasmon modes in optically-patterned linear nanoparticle arrays with separations on the order of the wavelength of light, demonstrating new mechanisms for coupling beyond the well-known near-field interactions. The collective excitation over the intermediate-scale arrays is also shown to redirect the scattered light perpendicular to the expected forward scattering. Next, we demonstrate that self-arranged optically bound linear arrays act as optical cavities for co-trapped single-photon emitters, modifying the local density of electromagnetic states in the vicinty of the nanoparticle system. Finally, we probe optically 'dark' modes in a core-satellite nanostructure by exciting magnetic responses separately from electric modes with structured excitation light.

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Watts, Clare. "Electromagnetic sensing of cell suspensions in microfluidic systems." Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/58859.

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Cancer is one of the leading causes of death worldwide, and cancers which metastasise, the process of cancer spreading from one organ to another within the body, have the highest fatality rates. Although the mechanism of metastasis is not well understood, the study of cells in the circulatory system which are known to seed tumours is of great importance in cancer research. Current methods for detection of such cells, although specific and sensitive, result in their destruction, and have drawbacks associated with a bias towards specific cell markers. This work seeks to assess the feasibility of using dielectric spectroscopy and the variation in dielectric properties of different cells at microwave frequencies to characterise and separate circulating tumour cells (CTCs) and other abnormal cells from peripheral circulating blood. This technique is non-destructive and label free, and opens the door to a flow-cytometer system based purely on the physical properties of different cells, capable of measuring them in their natural state. A novel coupled-resonator sensor is introduced in this work, and used to make dielectric measurements of polystyrene microspheres as well as single, flowing, viable cells of three different types at ~10 GHz. The results have been compared to Raman spectroscopy analysis of the cultured cells, showing potential correlation between the water content of the cell types investigated, and the response of the novel system. This is of diagnostic value, with cell hydration linked to carcinogenesis.

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Moss, Alison Jeanne. "The effects of applied fields on environmental systems." Thesis, Brunel University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272364.

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SARTORI, CARLOS A. F. "Aspectos de compatibilidade eletromagnética em estruturas atingidas por descargas atmosféricas." reponame:Repositório Institucional do IPEN, 1999. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11625.

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Made available in DSpace on 2014-10-09T12:54:00Z (GMT). No. of bitstreams: 0
Made available in DSpace on 2014-10-09T14:09:21Z (GMT). No. of bitstreams: 1 12436.pdf: 2191865 bytes, checksum: 12b10ebed00b6647c2de939f5f567b1d (MD5)
Tese (Doutoramento)
IPEN/T
Escola Politecnica, Universidade de Sao Paulo - POLI/USP

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Bedrosian, Paul Andrew. "Electromagnetic imaging of active fault zones /." Thesis, Connect to this title online; UW restricted, 2002. http://hdl.handle.net/1773/9791.

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Matandirotya, Electdom. "Measurement and modelling of geomagnetically induced currents (GIC) in power lines." Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2459.

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Thesis (DTech (Electrical Engineering))--Cape Peninsula University of Technology, 2016.
Geomagnetically induced currents (GIC) are currents induced in ground-based conductor networks in the Earth's surface. The GIC are driven by an electric eld induced by geomagnetic variations which are a result of time-varying magnetospheric-ionospheric currents during adverse space weather events. Several studies have shown that there is a likelihood of technological damage (the power grid) in the mid- and low-latitude regions that could be linked to GIC during some geomagnetic storms over the past solar cycles. The effects of GIC in the power system can range from temporary damage (e.g. protective relay tripping) to permanent damage (thermal transformer damage). Measurements of GIC in most substations are done on the neutral-to-ground connections of transformers using Hall-effect transducers. However, there is a need to understand the characteristics of GIC in the power lines connected to these transformers. Direct measurements of GIC in the power lines are not feasible due to the low frequencies of these currents which make current measurements using current transformers (CT) impractical. This thesis discusses two techniques that can be employed to enhance understanding GIC characteristics in mid-latitude regions. The techniques involve the measurement of GIC in a power line using differential magnetometer measurements and modelling GIC using the finite element method. Low frequency magnetometers are used to measure magnetic felds in the vicinity of the power lines and the GIC is inferred using the Biot-Savart law. A finite element model, using COMSOL-Multiphysics, is used to calculate GIC with the measured magnetic field and a realistic Earth conductivity profile as inputs. The finite element model is used for the computation of electric field associated with GIC modelling.

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Cotuk, Umit. "Scattering from multi-layered metamaterials using wave matrices." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Sep%5FCotuk.pdf.

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Rodríguez, Frías Myrna. "An electromagnetic spectrum aware indoor positioning system." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/an-electromagnetic-spectrum-aware-indoor-positioning-system(fbf361a9-d5aa-46e8-b905-8a26b2369a1a).html.

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The principal objectives of this research are: to investigate the performance of different fingerprint-based WiFi Indoor Positioning Systems (IPS), analyse historical long-term data signals, detection of signal change points and outliers; then present an enhanced method that generates temporal based fingerprints. The proposed method consists of analysing signal strength profiles over time and detecting points at which the profile behaviour changes. This methodology can be used to dynamically adjust the fingerprint based on environmental factors, and with this select the relevant Wireless Access Points (WAPs) to be used for fingerprinting. The use of an Exponentially Weighted Moving Average (EWMA) Control Chart is investigated for this purpose. A long-term analysis of the WiFi scenery is presented and used as a test-bed for evaluation of state-of-the-art fingerprinting techniques. Data was collected and analysed over a period of 18 months, with over 840 different WAPs detected in over 77,000 observations covering 47 different locations of varying characteristics. A fully functional IPS has been developed and the design and implementation is described in this thesis. The system allows the scanning and recording of WiFi signals in order to define the generation of temporal fingerprints that can create radio-maps, which then allow indoor positioning to occur. This thesis presents the theory behind the concept and develops the technology to create a testable implementation. Experiments and their evaluation are also included. Based on the timestamp experiments the proposed system shows there is still room level accuracy, with a reduction in radio-map size.

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

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Månsson, Daniel. "Intentional electromagnetic interference (IEMI) : Susceptibility investigations and classification of civilian systems and equipment." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9264.

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This PhD thesis addresses the threat posed to society by sources that can produce high power electromagnetic pulses (HEPM) and be used maliciously to disturb or damage electronic equipment. The vulnerability from intentional electromagnetic interference (IEMI) has increased in the recent decades due to the widespread dependence of the civil society on sensitive electronic systems and proliferation of radiation sources. As the characteristics of the disturbances associated with IEMI often have very high frequency content, the existing mitigation measures and protection components may not be adequate. It was seen that for ultra wideband (UWB) transients low voltage protection components may not work as intended, due to parasitic components that arises from the packaging of the device. The large spatial distribution of many civilian facilities and critical infra-structures (e.g., power generation, communications, train system, etc.) presents many unexpected ports for an attacker as the majority of the parts of these systems are not protected or secure. As the new European Rail Traffic Management System (ERTMS) will utilize wireless communication for communication and control of the trains the vulnerability from different radiating HPEM sources was investigated. Angles of incidence and frequencies that are a threat in a given situation are identified. Due to the possibility of unexpected ports, the propagation of differential mode ultra wideband transients in low voltage power networks, when injected into a power socket of a facility, was studied. The effects on the transient propagation from cable bends, switches and junctions were studied, both in a laboratory setup and in the network of a facility. Also, as modern electronic equipment and systems may not be tested for waveforms and disturbances other than standardized EMC tests, experiments on some common commercial-off-the-shelf (COTS) equipment were performed with non-standard test situation. It was seen that these could easily be disturbed or even permanently damaged. In addition, due to the inherent difficulties with IEMI, a new method for classifying facilities from IEMI is suggested. It is based on available terminology of accessibility (A), susceptibility (S) and consequence (C), but expands these and forms the so called IEMI/ASC-cube.

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Thomas, Scott James 1961. "Modeling and testing the LASI electromagnetic subsurface imaging systems." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/282186.

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Three frequency-domain electromagnetic subsurface profiling systems have been developed which use frequencies from 30Hz to 30kHz, 1kHz to 1MHz, and from 30kHz to 30MHz respectively. The systems operate in the near-field and measure the ellipticity of the magnetic field. A grounded wire or a vertical magnetic dipole is used as the transmitter antenna. The receiving antennas consist of three mutually orthogonal antennas which are placed on the ground in an arbitrary orientation. Instead of performing rotations in three-dimensional complex space, a simple two-dimensional rotation operating in the complex plane is used to find ellipticity and relative tilt angle in three dimensions. Cross-talk between the receiver coils and corrections for coil misalignment are corrected using fixed coefficients. By employing cross-talk and coil misalignment corrections, coil-orientation invariance is achieved. Algorithms using one-dimensional computer modeling are developed to determine the expected minimum and maximum depths of penetration as a function of system noise and anomaly amplitude. Optimum target depth is computed from three-layer one-dimensional computer modeling and compares well with the magneto-telluric depth in the far-field. A large 100,000 gallon concrete-lined basin has been designed and constructed to perform full-scale physical modeling of the system response to various objects. The basin has been filled with water to simulate a conductive medium and a variety of targets have been submerged in the basin to simulate targets. Initial results indicate data can be collected from surveys over the basin to train neural networks. Trained neural networks can then perform real-time modeling during routine surveys.

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Salandrino, Alessandro. "Electromagnetic propagation anomalies in waveguiding structures and scattering systems." Doctoral diss., University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5024.

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The effects related to diffraction and interference are ubiquitous in phenomena involving electromagnetic wave propagation, and are accurately predicted and described within the framework of classical electrodynamics. In the vast majority of the cases the qualitative features of the evolution of a propagating wave can be inferred even without detailed calculations. A field distribution will spread upon propagation, will accumulate phase along the direction of power flow, will exert mechanical forces upon scattering objects in the direction of propagation etc. When such predictions fail, counterintuitive effects and new functionalities can be engineered. In this work a series of exceptional cases under different degrees of field confinement have been isolated. In such instances the electromagnetic behavior significantly deviates from conventional cases. In particular, considering structures with monodimensional field confinement, the only possible class of diffraction free surface waves has been introduced. Again within the context of surface waves the mechanism of Enhanced Evanescent Tunneling (EET) has been proposed, which allows a net power flow to be sustained by evanescent fields only with applications to sub-diffraction imaging. Increasing the degree of field confinement, a unique class of fully dielectric waveguide arrays able to support negative effective index modes has been theoretically demonstrated. Finally the opto-mechanical consequences of such effective negative index environments have been studied, highlighting counterintuitive properties. Instrumental to these findings was the introduction of a general theory of optical forces in terms of vector spherical harmonics.
ID: 030423150; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2011.; Includes bibliographical references (p. 115-125).
Ph.D.
Doctorate
Optics and Photonics

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Martino, Carlos F. "On the effects of electromagnetic fields on biological systems." Connect to online resource, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3337129.

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Mosquera, Luis G. "Wastewater Disinfection in Enclosed Recirculation Systems with Electromagnetic Waves." ScholarWorks@UNO, 2013. http://scholarworks.uno.edu/td/1752.

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Finding the most cost-effective and environmental friendly way to treat and disinfect wastewater has been raising concerns around the world. Failure in performing disinfection of wastewater before returning it to the environment could have terrible consequences to human health and the ecosystem. The risks associated to continue with current practices have led to the creation of stringent regulations. In this research the HYDROPATH technology is tested while attaching a HydroFlow 60i unit to a reactor that works as a closed recirculation system. To determine the feasibility of the HydroFlow 60i unit as an alternative method to chlorine, the EPA method 1306 is used being Escherichia coli the unit of quantification. After performing several experiments modifying parameters such as conductivity and detention time, it was concluded that the HydroFlow 60i unit by itself would not able to replace current disinfection technologies, to meet EPA standards of E. coli removal.

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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, Ming. "Electromagnetic radiation calorimetry of thermoplastics, elastomers and composites systems." Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54780.

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The application of microwave radiation for processing of glassy and semicrystalline thermoplastics, elastomeric polymers and composites was investigated. The goal of this research was to reveal the relationship between polymer structure and microwave absorptivity, and hence processability. The specimens were subjected to an electric field at 2.45 GHz either inside a rectangular waveguide or in a cylindrical resonant cavity applicator with less than 100 watts applied power. Both travelling wave modes and standing wave modes were examined. Temperatures, powers and times were recorded, leading to the concept of "microwave calorimetry." Low frequency dynamic mechanical and dielectric frequency-temperature spectra were obtained on the materials and combined to conveniently extrapolate structure-property relationships into the GHz region. A correlation was found between the dielectric properties of various polymers and the dipole moments of small molecule analogues. Evaluating heatability was most accurately found to be determined by the magnitude of (ε_S - ε_∞), the oscillator strength. The value of (ε_S - ε_∞) should be used together with the distribution of relaxation times and the activation energies of dipolar dispersion to predict heatability for microwave processing. The critical temperatures, T_C, of dielectric loss were obtained from the intercepts of positive slope tangents of heating rate versus temperature plots at 2.45 GHz for polymers. Microwave processing was rapid above the critical temperature where the maximum dielectric loss fell in the 2.45 GHz frequency domain for efficient coupling of energy to the polymers. Shifting the dielectric relaxation spectrum into the microwave region by directly or indirectly increasing the temperature of each sample was unique and of key importance to processability. A schematic model was proposed to explain the behavior of two-phase materials subjected to microwave heating. Combining the heatability, (ε_S - ε_∞), and the dielectric relaxation spectral response was found to be helpful in evaluating formulations of two-phase materials for electromagnetic radiation processing at high frequencies.
Ph. D.

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32

Davis, John G. "Electromagnetic field pattern synthesis in overmoded coaxial waveguide systems." Thesis, University of Manchester, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.601114.

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High Q coaxial waveguide devices are found in superior performance filters for wireless applications, they are used with cavity perturbation techniques to measure complex permittivity, they underpin the operation of scanning microwave microscopes and are of ongoing importance in the design of space division multiple access beamforming antennas. The coaxial 'T' junction transition formed between the feed and the coaxial waveguide airspace is a key junction in all of these waveguide coaxial systems. The study of this transition was the starting point for this research. In previous literature, a Green's theorem has been used to characterise a coaxial 'T' junction. In this thesis the model has been extended to include higher order propagating modes, evanescent modes, partial and full height probes, and any general form of coaxial termination. The final model is capable of analysing the S-parameters of multiport coaxial devices, and the energy distribution of the modes within the coaxial airspace. Several different coaxial systems were constructed and experimentally investigated including a coaxial resonator, a non-standard coaxial waveguide unknown load, and a beamforming antenna. In all cases the dyadic Green's function model was demonstrated to model accurately the performance of the multi-mode coaxial system. The major advantage of this approach is its inherent closed form nature lending itself to a computationally efficient means of formulating Sparameters, synthesising field patterns within the waveguide airspace and for shaping beam forming antenna radiation patterns. The model has successfully been applied to the design and experimental validation of the algorithm for several overmoded coaxial applications including: coaxial load characterisation, overmoded characteristic impedance formulations, overmoded resonant cavity and SDMA beamforming antenna design. Further applications to material measurement, direction of arrival estimations and mutual compensation matrices for antenna beamformers are under review. In essence, a powerful generic tool for the design and prediction of the electromagnetic characteristics of single and multiple probe overmoded coaxial devices has arisen from this investigation.

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Hempy, Alexander James. "Standalone Antenna Demonstration System." DigitalCommons@CalPoly, 2010. https://digitalcommons.calpoly.edu/theses/319.

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Antenna systems play a significant role in today’s electronic communications. They are essential for cell phones, satellites, radio, and radar among many other important applications. This paper describes the design, assembly, and operation of an antenna demonstration system designed to instill interest in the field of antenna design among high school and undergraduate college students. The system is portable, supplied solely by DC power supplies, easily reproducible, and includes rotational axes to illustrate antenna performance limitations and requirements. It provides a visual indication of wireless signal strength and demonstrates several antenna performance characteristics including polarization, gain and directivity, radiation patterns - nulls and maximums, and spreading loss. Several antenna types used in present-day applications (embedded and reflector antennas), in addition to structural barriers encountered in typical operating environments, are used to define wireless system performance. Students gain insight on radiating structure and orientation effects on antenna system characteristics and hopefully develop interest in future wireless studies.

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Jump, Addison B. "Mathematical analysis of a large-gap electromagnetic suspension system." Diss., This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-06062008-154655/.

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Matos, Abiague Alex. "Dynamics of quantum systems driven by half-cycle electromagnetic pulses." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=975601326.

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Wang, Lei. "Modeling of the armature-rail interface in an electromagnetic launcher with lubricant injection." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26519.

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Thesis (Ph.D)--Mechanical Engineering, Georgia Institute of Technology, 2009.
Committee Chair: Salant, Richard F.; Committee Member: Bair, Scott; Committee Member: Cowan, Richard S; Committee Member: Danyluk, Steven; Committee Member: Scott, Waymond R. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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Charlesworth, Alexander E. "A class of staggered grid algorithms and analysis for time-domain Maxwell systems." Thesis, Colorado School of Mines, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10010857.

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We describe, implement, and analyze a class of staggered grid algorithms for efficient simulation and analysis of time-domain Maxwell systems in the case of heterogeneous, conductive, and nondispersive, isotropic, linear media. We provide the derivation of a continuous mathematical model from the Maxwell equations in vacuum; however, the complexity of this system necessitates the use of computational methods for approximately solving for the physical unknowns. The finite difference approximation has been used for partial differential equations and the Maxwell Equations in particular for many years. We develop staggered grid based finite difference discrete operators as a class of approximations to continuous operators based on second order in time and various order approximations to the electric and magnetic field at staggered grid locations. A generalized parameterized operator which can be specified to any of this class of discrete operators is then applied to the Maxwell system and hence we develop discrete approximations through various choices of parameters in the approximation. We describe analysis of the resulting discrete system as an approximation to the continuous system. Using the comparison of dispersion analysis for the discrete and continuous systems, we derive a third difference approximation, in addition to the known (2, 2) and (2, 4) schemes. We conclude by providing the comparison of these three methods by simulating the Maxwell system for several choices of parameters in the system

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Cole, Gareth Douglas. "Design of an automated calibration device for electromagnetic tracking systems." Online access for everyone, 2007. http://www.dissertations.wsu.edu/Thesis/Spring2007/g_cole_050107.pdf.

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39

Monsefi, Farid. "Mathematical modeling of electromagnetic disturbances in railway system." Licentiate thesis, Luleå : Luleå University of Technology, 2006. http://epubl.ltu.se/1402-1757/2006/50/LTU-LIC-0650-SE.pdf.

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Chaudhary, Arvind K. S. "Protection system representation in the Electromagnetic Transients Program." Diss., This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-07282008-134541/.

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Moon, Jinyeong. "Electromagnetic energy harvester and self-powered embedded system." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/106088.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2016.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 289-293).
Energy harvesting offers an important design option for creating sensing and control elements without a requirement for custom wiring or batteries. The independent and care-free nature of energy harvesting enables monitoring devices to penetrate wider and deeper into our daily lives, making accommodation of fine sensing and control for condition-based maintenance ever more feasible. Finer granularity in sensing and control, which is the future of energy efficiency, alone is an immense benefit as it can reduce time and cost associated with a potential repair. Combined with condition-based maintenance, it can prevent potential down-time of a machine under monitoring. An exciting possibility creates a "self-powered" embedded system with an integrated energy harvester for electromechanical diagnosis. This non-intrusive energy harvester is designed to extract energy from magnetic fields around a power line of a load, in the manner of a current transformer. In contrast to the conventional usage of magnetic elements, such as transformers and inductors, the analysis on this "current transformer" reveals a critical result: for any given core for any particular application, power harvest is maximized when the core is permitted to saturate at an opportune time in the line cycle. The design of this integrated energy harvester is fully explored in the thesis, including: development of new models to incorporate a fully saturating magnetic core for simulation; designs of power electronics circuits for maximizing power harvest; and integration of the harvester into the embedded system as a practical power supply. The design of a self-powered and low-power embedded system, vibration assessment monitoring point with integrated recovery of energy (VAMPIRE), is discussed in depth in the thesis. The overall architecture of the embedded system is first presented, followed by designs of individual subsystems, the power package and the sensor package. In the power package, initialization, energy buffer, power interfaces, power regulation, and microcontroller design are explored. In the sensor package, power budget, sensors, data storages, storage management, wireless communication, and corresponding user interfaces are explored. Finally, impedance spectroscopy for an electromechanical load is discussed. Using the electrical and vibrational data that are nonintrusively collected from electromagnetically self-powered embedded system, structural issues of the load, i.e., changes in the stiffness of mounts and the imbalance of a shaft, can be clearly identified, making it feasible for this self-powered embedded system to be used for condition-based maintenance.
by Jinyeong Moon.
Ph. D.

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42

Minerskjöld, Maxim. "Sensors, signals and systems for electromagnetic radiation experiments in physics /." Stockholm, 1998. http://www.lib.kth.se/abs98/mine0528.pdf.

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Aloi, Daniel Nicholas. "Electromagnetic analysis of ground multipath for satellite-based positioning systems." Ohio : Ohio University, 1996. http://www.ohiolink.edu/etd/view.cgi?ohiou1178816934.

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44

Grieve, M. D. "Self-adaptive methods for computer-aided design of electromagnetic systems." Thesis, University of Aberdeen, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382136.

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Aloi, Daniel N. "Electromagnetic analysis of ground multipath for satellite-based positioning systems." Ohio University / OhioLINK, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1178816934.

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46

Fukuhara, Hajime. "Miniaturization and Integration of Measurement Systems for Space Electromagnetic Environments." 京都大学 (Kyoto University), 2012. http://hdl.handle.net/2433/161016.

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47

Simmons, Daniel. "Hybrid methods for modelling advanced electromagnetic systems using unstructured meshes." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/33230/.

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The aim of this project is the conception, implementation, and application of a simulation tool for the accurate modeling of electromagnetic fields within inhomogeneous materials with complex shapes and the propagation of the resulting fields in the surrounding environment. There are many methods that can be used to model the scattering of an electromagnetic field, however one of the most promising for hybridisation is the Boundary Element Method (BEM), which is a surface technique, and the Unstructured Transmission Line Modeling (UTLM) method, which is a volume technique. The former allows accurate description of the scatterer's boundary and the field's radiation characteristics, but cannot model scattering by materials characterized by a non-uniform refraction index. The latter, on the contrary, can model a very broad range of materials, but is less accurate, since it has to rely on approximate absorbing boundary conditions. A method resulting in the hybridisation of BEM and UTLM can be used to construct a tool that takes into account both the interaction with non-uniform tissue and propagation in its environment. The project aims to describe in detail the implementation of the novel method, and deploy it in a heterogeneous distributed computing environment.

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48

Dayanikli, Gokcen Yilmaz. "Electromagnetic Interference Attacks on Cyber-Physical Systems: Theory, Demonstration, and Defense." Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/104862.

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A cyber-physical system (CPS) is a complex integration of hardware and software components to perform well-defined tasks. Up to this point, many software-based attacks targeting the network and computation layers have been reported by the researchers. However, the physical layer attacks that utilize natural phenomena (e.g., electromagnetic waves) to manipulate safety-critic signals such as analog sensor outputs, digital data, and actuation signals have recently taken the attention. The purpose of this dissertation is to detect the weaknesses of cyber-physical systems against low-power Intentional Electromagnetic Interference (IEMI) attacks and provide hardware-level countermeasures. Actuators are irreplaceable components of electronic systems that control the physically moving sections, e.g., servo motors that control robot arms. In Chapter 2, the potential effects of IEMI attacks on actuation control are presented. Pulse Width Modulation (PWM) signal, which is the industry–standard for actuation control, is observed to be vulnerable to IEMI with specific frequency and modulated–waveforms. Additionally, an advanced attacker with limited information about the victim can prevent the actuation, e.g., stop the rotation of a DC or servo motor. For some specific actuator models, the attacker can even take the control of the actuators and consequently the motion of the CPS, e.g., the flight trajectory of a UAV. The attacks are demonstrated on a fixed-wing unmanned aerial vehicle (UAV) during varying flight scenarios, and it is observed that the attacker can block or take control of the flight surfaces (e.g., aileron) which results in a crash of the UAV or a controllable change in its trajectory, respectively. Serial communication protocols such as UART or SPI are widely employed in electronic systems to establish communication between peripherals (e.g., sensors) and controllers. It is observed that an adversary with the reported three-phase attack mechanism can replace the original victim data with the 'desired' false data. In the detection phase, the attacker listens to the EM leakage of the victim system. In the signal processing phase, the exact timing of the victim data is determined from the victim EM leakage, and in the transmission phase, the radiated attack waveform replaces the original data with the 'desired' false data. The attack waveform is a narrowband signal at the victim baud rate, and in a proof–of–concept demonstration, the attacks are observed to be over 98% effective at inducing a desired bit sequence into pseudorandom UART frames. Countermeasures such as twisted cables are discussed and experimentally validated in high-IEMI scenarios. In Chapter 4, a state-of-art electrical vehicle (EV) charger is assessed in IEMI attack scenarios, and it is observed that an attacker can use low–cost RF components to inject false current or voltage sensor readings into the system. The manipulated sensor data results in a drastic increase in the current supplied to the EV which can easily result in physical damage due to thermal runaway of the batteries. The current switches, which control the output current of the EV charger, can be controlled (i.e., turned on) by relatively high–power IEMI, which gives the attacker direct control of the current supplied to the EV. The attacks on UAVs, communication systems, and EV chargers show that additional hardware countermeasures should be added to the state-of-art system design to alleviate the effect of IEMI attacks. The fiber-optic transmission and low-frequency magnetic field shielding can be used to transmit 'significant signals' or PCB-level countermeasures can be utilized which are reported in Chapter 5.
Doctor of Philosophy
The secure operation of an electronic system depends on the integrity of the signals transmitted from/to components like sensors, actuators, and controllers. Adversaries frequently aim to block or manipulate the information carried in sensor and actuation signals to disrupt the operation of the victim system with physical phenomena, e.g., infrared light or acoustic waves. In this dissertation, it is shown that low-power electromagnetic (EM) waves, with specific frequency and form devised for the victim system, can be utilized as an attack tool to disrupt, and, in some scenarios, control the operation of the system; moreover, it is shown that these attacks can be mitigated with hardware-level countermeasures. In Chapter 2, the attacks are applied to electric motors on an unmanned aerial vehicle (UAV), and it is observed that an attacker can block (i.e., crash of the UAV) or control the UAV motion with EM waves. In Chapter 3, it is shown that digital communication systems are not resilient against intentional electromagnetic interference (IEMI), either. Low–power EM waves can be utilized by attackers to replace the data in serial communication systems with a success rate %98 or more. In Chapter 4, the attacks are applied to the sensors and actuators of electric vehicle chargers with low–cost over–the–shelf amplifiers and antennas, and it is shown that EM interference attacks can manipulate the sensor data and boosts the current supplied to the EV, which can result in overheating and fire. To ensure secure electronic system operation, hardware–level defense mechanisms are discussed and validated with analytical solutions, simulations, and experiments.

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Oh, Sang Joon. "Electromagnetics of inertial energy storage systems with fast electromechanical energy conversion /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.

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

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Dissertations / Theses on the topic 'Electromagnetical systems'

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