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Dissertations / Theses on the topic 'Electromagnetic'
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1
Bekele, Ephrem Teshale. "Innovative Electromagnetic Field Manipulating Devices Based on Transformation Electromagnetics." Doctoral thesis, Università degli studi di Trento, 2015. https://hdl.handle.net/11572/368574.
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Quasiconformal Transformation Optics (QCTO) has been investigated and applied for the design of innovative electromagnetic field manipulating devises. The design is focused on enhancing radiation performance of antenna arrays. Towards this end, the QCTO approach has been utilized for the application of compressing dimension of linear array at the same time keeping its radiation performance equivalent to the original array. The basic QCTO is then generalized to allow an arbitrary physical arrangement coated with a suitable lens to exhibit the same radiating features of an arbitrary reference virtual array in free space. This removed the limitation on the state-of-the-art QCTO method to handle transformation between arbitrarily shaped geometries. A representative numerical example, concerned with a two-dimensional layout, is presented to assess the effectiveness of the proposed method as well as the enhanced features of the resulting metamaterial-coated arrays with respect to standard conformal arrangements. In addition, the capability to achieve significantly simplified structures by means of tile discretization approximation of the synthesized lens is investigated. Selected numerical examples are reported to illustrate the effectiveness of tile-discretized lenses versus ideal QCTO arrangements. The metamaterial lens that resulted from the extended QCTO was found to be significantly anisotropic posing implementation challenge. To address this issue, an innovative approach, based on the System-by-Design (SbD) paradigm, is proposed for the synthesis of isotropic non-magnetic metamaterial lenses. Selected numerical results, concerned with an application of the SbD-QCTO approach, are reported to give some insights on its advantages and current limitations in terms of computational efficiency, effectiveness, and flexibility.
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Bekele, Ephrem Teshale. "Innovative Electromagnetic Field Manipulating Devices Based on Transformation Electromagnetics." Doctoral thesis, University of Trento, 2015. http://eprints-phd.biblio.unitn.it/1499/1/Ph.D.Thesis.BEKELE-April.2015.Final.pdf.
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Quasiconformal Transformation Optics (QCTO) has been investigated and applied for the design of innovative electromagnetic field manipulating devises. The design is focused on enhancing radiation performance of antenna arrays. Towards this end, the QCTO approach has been utilized for the application of compressing dimension of linear array at the same time keeping its radiation performance equivalent to the original array. The basic QCTO is then generalized to allow an arbitrary physical arrangement coated with a suitable lens to exhibit the same radiating features of an arbitrary reference virtual array in free space. This removed the limitation on the state-of-the-art QCTO method to handle transformation between arbitrarily shaped geometries. A representative numerical example, concerned with a two-dimensional layout, is presented to assess the effectiveness of the proposed method as well as the enhanced features of the resulting metamaterial-coated arrays with respect to standard conformal arrangements. In addition, the capability to achieve significantly simplified structures by means of tile discretization approximation of the synthesized lens is investigated. Selected numerical examples are reported to illustrate the effectiveness of tile-discretized lenses versus ideal QCTO arrangements. The metamaterial lens that resulted from the extended QCTO was found to be significantly anisotropic posing implementation challenge. To address this issue, an innovative approach, based on the System-by-Design (SbD) paradigm, is proposed for the synthesis of isotropic non-magnetic metamaterial lenses. Selected numerical results, concerned with an application of the SbD-QCTO approach, are reported to give some insights on its advantages and current limitations in terms of computational efficiency, effectiveness, and flexibility.
3
Sainath, Kamalesh K. "Robust Numerical Electromagnetic Eigenfunction Expansion Algorithms." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1480340627500682.
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Lei, Feiran. "Homogenization of Heterogeneous Composites by Using Effective Electromagnetic Properties." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1299513068.
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Bau-Hsing, Ann. "Computer-aided electromagnetic analysis of chokes and transformers." The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu1438255468.
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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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Zhu, Boyuan. "The Electromagnetic Compatibility Problems of Integrated Circuits." Thesis, Griffith University, 2011. http://hdl.handle.net/10072/365527.
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With the constant speed of growth in semiconductor technology, integrated
circuit (IC) has taken a considerable position in an electronic system. The
integrated circuit is working in a low supply voltage with high operation
frequency. The internal complexity and chip density are also increased
dramatically. Modern microelectronic technology in wafer fabrication
easily allows component densities to exceed one million transistors per
die. So far, integrated circuits are suering from various and complicated
electromagnetic environments. Being the heart of an electronic system,
stability and reliability of the integrated circuit are of the most important
requirement along with the techniques development. The demands of high
electromagnetic compatibility (EMC) performance for integrated circuits are
therefore broadly spread among semiconductor manufacturers and product
users.
Traditionally, EMC for IC is only considered at the post-design stage.
Once built, it is only then that equipment is tested to see whether or
not it conforms to the relevant standards. This can prove very expensive
in terms of time, cost, and the potential need for retrot modications.
Simulating a piece of equipment is potentially much faster and cheaper than
taking a prototype or existing piece of equipment to a test-house. More
importantly, it allows the engineer to \look into" the equipment and see
where currents and elds are largest; this is almost impossible with physical
testing. Recently, computational electromagnetics (CEM) technique has
moved from pure mathematical analysis into design in engineering practice.
It can provide a much easier, faster and more economical solution of
prediction in EMC characteristics than conventional methods. Thus, EMC
computer modelling and simulation of IC is going to play an important role
in scientic research and industrial applications.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Engineering
Science, Environment, Engineering and Technology
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8
Park, Young C. (Young Chul) 1960. "A Study of Some Biological Effects of Non-Ionizing Electromagnetic Radiation." Thesis, University of North Texas, 1996. https://digital.library.unt.edu/ark:/67531/metadc278105/.
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The experimental studies of this work were done using a microwave cavity spectrometer, Escherichia coli (E-coli) bacteria, and other peripheral equipment. The experiment consists of two steps. First, a general survey of frequencies from 8 GHz to 12 GHz was made. Second, a detailed experiment for specific frequencies selected from the first survey were further studied. Interesting frequency dependent results, such as unusually higher growing or killing rates of E-coli at some frequencies, were found. It is also concluded that some results are genetic, that is, the 2nd, and 3rd subcultures showed the same growing status as the 1st cultures.
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Stevenson, Adrian Carl. "Electromagnetic biosensors." Thesis, University of Cambridge, 1995. https://www.repository.cam.ac.uk/handle/1810/252090.
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Cuff, David P. (David Preston). "Electromagnetic nanopositioner." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/38712.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references (p. 195-200).
This thesis presents the analysis, design, and control of a new class of magnetic nanopositioner. Applications for this class of positioner include sample positioning for scanning microscopy and interferometry, nanofabrication, vibration cancellation, biological cell tracking/positioning, and beam focusing/steering. The nanometer-resolution positioning required in these applications is often provided using piezoelectric ceramic actuators. The drawbacks to using piezoelectric actuators include high hysteretic heating, lightly damped structural resonances, the need for preload on the actuator stack, as well as the requirement for a high voltage amplifier. This thesis demonstrates an electromagnetically driven nanopositioner that is suspended on rubber bearings as a promising, low cost alternative to the piezoelectric nanopositioners. Several key features of the electromagnetic nanopositioner are the flux-steering actuator that applies a force linear in both coil current and displacement, replacement of the conventional metal flexures with rubber bearings, as well as power and sense electronics that can be easily integrated into a compact package. A prototype of this class of nanopositioner with 100,pm of travel and a maximum force output of 460 N was built and tested.
(cont.) A closed-loop bandwidth of 580 Hz was obtained using capacitance distance sensor feedback. The feasibility and procedure for casting rubber bearings was investigated. Several room-temperature vulcanizing (RTV) rubbers were considered for low volume, in-lab production of test specimens. A compression specimen was cast from a two-part RTV silicone rubber that was found to be suitable. A compression fixture that was previously used to test bonded rubber pads was modified to accept the cast rubber bearings. The cast rubber bearing was found to have the predicted DC stiffness and the stiffness increased with frequency as expected. Casting of rubber bearings was demonstrated as a feasible method for putting rubber bearings into devices such as nanopositioners.
by David P. Cuff.
S.M.
11
Nouri, Farnoosh Massoudian. "Electromagnetic aftereffects of near-death experiences." Thesis, University of North Texas, 2008. https://digital.library.unt.edu/ark:/67531/metadc9054/.
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The purpose of this quantitative study was first to investigate the comparative incidence of electromagnetic aftereffects (EMEs) during the past year among near-death experiencers (NDErs), people who experienced a close brush with death without an NDE (CBrs), and people who reported never having experienced a close brush with death (LCErs). The second purpose was to investigate a possible change in EME incidence among the three groups before and after a critical life event. The third purpose was to investigate the relationship between the reported overall depth and specific components of the subjective experiences of people who have had a close brush with death -- NDErs and CBrs -- and their reported incidence of EMEs. I used the Near-Death Experience Scale (Greyson, 1983), and developed the Close Brush with Death Question form, Life Changing Event Question form, and Electromagnetic Effects Questionnaire for this study. The final sample included 36 NDErs, 20 CBrs, and 46 LCErs. The results of this study firmly supported more reported problems with EM devices experienced by NDErs compared to CBrs or LCErs. Especially with respect to EM devices such as lights and cell phones, as well as the emotional state of individuals affecting EM devices, this study showed more reports of problems with these devices between before and after NDEs for NDErs compared to before and after a life changing event for LCErs. Moreover, findings of this study showed a correlation between the depth of NDEs and EMEs. This study has important implications for counselors working with NDErs. Findings from this study show that NDErs have a strong possibility of experiencing electromagnetic interferences when close to electromagnetic devices such as cell phones, computers, lights, and watches after their NDEs. This phenomenon can be a stressor in the lives of NDErs and their families and friends. As some participants in this study indicated, information about EMEs can reduce NDErs' stress. Thus, counselors can use information from this study to psychoeducate their NDEr clients and work with them to develop strategies to cope with EMEs, thereby hopefully reducing the stress of EME-related NDE aftereffects.
12
Fouda, Ahmed Elsayed. "Electromagnetic Time-Reversal Imaging and Tracking Techniques for Inverse Scattering and Wireless Communications." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366202740.
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Moon, Haksu. "Robust Algorithms for Electromagnetic Field Computation with Conduction Currents and Kinetic Charge-Transport Models." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1440193844.
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Vong, Poh Kheong. "Finite element modelling of electromagnetic and coupled thermo-electromagnetic devices." Thesis, University of Bath, 2001. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760775.
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Bayat, Masoumeh. "Electromagnetic composite nanofibers." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/39894.
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Multifunctional composite nanofibers containing magnetite (Fe₃O₄) nanoparticles are developed
in this work. The multifunctional composite nanofibers are proved to be electrically conductive
and magnetically permeable. Polyacrylonitrile (PAN) is used as an appropriate polymer which is
capable of being pyrolized to produce electrically conductive carbon nanofiber matrix. In order
to develop magnetic nanofibers, various amounts of Fe₃O₄ nanoparticles ranging from 3 to
10wt.% are embedded in the PAN nanofiber matrix. In addition, the electromagnetic behaviour
of nanocomposites made of two different sizes (GA:20-30nm and GB:10-20nm) of Fe₃O₄
nanoparticles is examined. Electrospun composite nanofibers are thermally treated at both 700°C
and 900°C to produce electromagnetic carbon nanofiber composites. The composite nanofibers
are characterized using scanning electron microscopy (SEM), transmission electron microscopy
(TEM), X-ray diffractometry (XRD), Raman spectroscopy, four-point probe and
Superconducting Quantum Interference Device (SQUID). Electromagnetic Interference
Shielding Effectiveness (EMI SE) of the pristine carbon nanofibers as well as electromagnetic
composite nanofibers is examined using Vector Network Analyzer with Thru-Reflect-Line
(TRL) calibration. Uniform nanofibers are obtained for all samples with choosing 10wt.% PAN
concentration in Dimethylformamide (DMF) with larger fiber diameters for composite
nanofibers as compared with pristine carbon nanofiber. The magnetic properties of Fe₃O₄
nanoparticles are successfully transferred into the as-spun Fe₃O₄/PAN composite nanofibrous
structure. The electromagnetic properties of the composite materials are tuned by adjusting the
amount and size of Fe₃O₄ nanoparticles in the matrix and carbonization process. By embedding
10wt.% of GA:20-30nm Fe₃O₄ nanoparticle, saturation magnetization (Ms) of 16emu/g is obtained with electrical conductivity of 9.2S/cm for composite nanofiber carbonized at 900°C. However, the Ms and electrical conductivity values respectively decrease to 9.0emu/g and 1.96S/cm for composite made of 10wt.% GB:10-20nm Fe₃O₄ nanoparticle carbonized at 900°C. The high surface area provided by the ultrafine fibrous structures, the flexibility and tuneable electromagnetic properties are expected to enable the expansion of the design options for a wide range of electronic devices such as sensors and actuators as well as Electromagnetic Interference Shielding Effectiveness (EMI SE). The electromagnetic composite nanofibers are demonstrated to act as strong electromagnetic interference shield of up to 70-80dB.
16
von, Keyserlingk Erik. "Electromagnetic Compatibility Scanner." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-285568.
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With the increasing amount of wireless devices in use today. All from Bluetooth headphonesto smart fridges, which communicates wirelessly to a server or phone. The needfor the radio frequency spectrum to be free from disturbances is necessarily. There aretoday regulations stating how much a device is allowed to transmit into the radio frequencyspectrum, this is to prevent and control disturbances from electronics whichdoes not intend to transmit into the radio frequency domain. In this report a setupis proposed to conduct near eld scanning of planar surfaces such as PCBs. This tolocate if a trace of component is transmitting or if the transmitted energy is higherthan allowed. This report includes verication of self made probes through tests andsimulation as well as comparison with commercially available probes. As well as evaluationof a robotic arm for use as the probe mover and the evaluating of a softwaredened radio with amplier.Antalet trådlösa enheter som tillkommer idag ökar stadigt. Allt från bluetooth hörlurartill smarta kylskåp som kommunicerar trådlöst med en server, telefon eller liknande. Detta innebär att radio-spektrumet behöver vara fri från störningar. Idag finns det bestämmelser som säger hur mycket en elektonisk produkt är tillåten att sända ut i radio-spektrumet, både för kommunikation och oavsiktligt transmittering. Detta är för att kontrollera och förebygga utsända störningar från från elektronik som kan störa kommunikation och vetenskapliga mätningar. I denna rapport utvärderas ett system som kan skanna ett område för dess närfält, både det magnetiska och elektriska fält. Ett sådant område är typiskt en PCB eller annan elektronisk konstruktion. Detta för att kunna lokalisera komponenter eller ledningar som radierar energi . Denna rapport beskriver tillverkning av närfältsprober med simulering och verifikation jämfört med kommersiella prober av test över ett tillverkat testkort. Utöver det utvärderas en robot arm som används för att flytta en probe över det område av intresse samt utvärderingav en software defined radiotillsammans med en förstärkare.
17
Schonhardt, Stefan. "Electromagnetic comb-drives." Tönning Lübeck Marburg Der Andere Verl, 2009. http://d-nb.info/995770131/04.
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Wang, Xiaochuan. "A Domain Decomposition Method for Analysis of Three-Dimensional Large-Scale Electromagnetic Compatibility Problems." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1338376950.
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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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Young, André. "Mesh termination schemes for the finite element method in electromagnetics /." Link to the online version, 2007. http://hdl.handle.net/10019/735.
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Sundberg, Garth. "Numerical Modeling of Electromagnetic Scattering in Explosive Granular Media." PDXScholar, 2010. https://pdxscholar.library.pdx.edu/open_access_etds/865.
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Terahertz (THz) reflection and transmission spectroscopy is a promising new field with applications in imaging and illicit material detection. One particularly useful application is for the detection of improvised explosive devices (IEDs) which is a favorite weapon of global terrorists. Explosive materials have been shown to have a unique spectral signature in the THz band which can be used to identify the explosives. However, the initial measurements performed on the explosive samples do not account for the modulation of the spectral features by random scattering that will be prevalent with actual samples encountered in applications. The intent of this work is to characterize and quantify the effects of random scattering that may alter the spectral features. Specifically, the effect that a randomly rough surface and granular scattering has on the scattered THz wave (T-Rays) will be investigated and characterized using the Finite-Difference Time-Domain (FDTD) simulation method. The FDTD method is a natural choice for this work as it can handle complicated geometries (i.e., multiple scatterers, arbitrarily rough interfaces, etc.) arbitrary materials (i.e., dispersive media, etc.) and provides broadband frequency data with one simulation pass. First, the effect that the randomly rough surface of the sample explosive has on the extracted spectral signature will be studied using a Monte-Carlo analysis. Then the effect of the complex structure inside the explosive material (the granular scatterers) will be considered. Next, when the physics of the rough surface and granular scattering are understood, a robust method to extract the spectral signature from the reflected T-rays will be developed.
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Liebfried, Oliver. "The Investigation of Electromagnetic Processes in Electromagnetic Launchers Using Colossal Magnetoresistance Sensors." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2011~D_20110615_180000-02329.
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The development of rails and armatures which ensure a sliding solid-to-solid contact during the whole projectile acceleration is a great challenge in the field of railgun technology. Multifaceted physics exists at the sliding contact interface: The current concentrates at the rear of the interface due to magnetic diffusion processes and the fast armature movement. Consequently, Joule heating leads to enhanced wear in this region. In this dissertation, magnetic diffusion in railguns is investigated by means of measuring magnetic fields with CMR-B-scalar sensors at static and dynamic experimental conditions. These novel sensors, based on La0.83Sr0.17MnO3 thin films exhibiting colossal magnetoresistance were adapted for the use at railguns. It was found that these sensors are effective tools to measure the magnitude of high pulsed magnetic fields independent of the field orientation. Magnetic field distributions influenced by proximity and velocity skin effect could be measured in the harsh railgun environment. The obtained results allowed to estimate the skin depth in the rails at the sliding interface of a fast moving armature (>1500m/s). Furthermore experiments with fixed multiple brush armatures showed that front brushes can have contact problems in case of missing contact pressure.Pagrindiniai bėgių tipo elektromagnetinių svaidyklių technologijos uždaviniai yra susiję su daugybe fizikinių reikinių, vykstančių sviedinio kontaktų sąlyčio su bėgiais riboje. Todėl elektromagnetinių procesų, atsirandančių dėl didelių elektros srovės tankių ir slydimo greičių tyrimas yra svarbus šios srities uždavinys. Dėl magnetinės difuzijos ir greito sviedinio judėjimo, srovė koncentruojasi galinėje kontakto dalyje, kuri dėl stipraus Joule šilimo greitai susidėvi, o tai apriboja svaidyklės efektyvumą. Disertacijoje pateikiami magnetinio lauko difuzijos tyrimai bėgių tipo svaidyklėse panaudojant specialius jutiklius magnetinių laukų matavimui. Šie nauji jutikliai, pagaminti iš plonų La0,83Sr0,17MnO3 sluoksnių, pasižyminčių milžiniškos magnetovaržos (MM) reiškiniu (MM-B-skaliariniai jutikliai), buvo pritaikyti svaidyklėse, veikiančiose statiniame ir dinaminiame režime, esant dideliems elektromagnetinių triukšmų lygiams ir mechaniniams įtempiams. Darbo metu buvo nustatyta, jog šiais jutikliais galima išmatuoti stipraus magnetinio lauko impulso amplitudę, kai nėra žinoma šių laukų kryptis. Buvo ištirti nevienalyčių magnetinių laukų pasiskirstymai bėgiuose, atsirandantys dėl artumo efekto bei greičio skinefekto, sviediniui judant greičiau nei 1500m/s. Bandymai su įtvirtintu daugelio šepetėlių konstrukcijos sviediniu parodė, kad priekiniai šepetėliai, dėl nepakankamo Lorenco jėgos sukuriamo slėgio, gali pararasti elektrinį kontaktą su bėgiais.
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Padmanabhan, Mahadevan. "Wrinkling and Springback in Electromagnetic Sheet Metal Forming and electromagnetic Ring Compression." The Ohio State University, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=osu1393078676.
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Vallon, Henri. "Focusing high-power electromagnetic waves using time-reversal." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLC006/document.
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L'objectif de la thèse a été de mettre en place dans un premier temps des modèles analytiques et statistiques permettant d'évaluer les performances d'un système à retournement temporel de fortes-puissances puis de les vérifier grâce à des mesures.Des campagnes de mesures ont alors permis de vérifier les modèles. Des simulations numériques ont aussi montrées les possibilités offertes par un tel système.En parallèle, des travaux sur l'impact des antennes dans une chambre réverbérantes ont été menés afin d'évaluer les performances d'un système ayant plusieurs sorties.Les résultats de thèses ont permis l'élaboration de nouvelles métriques des performances du système.Le développement d'un prototype a nécessité la conception et la réalisation de chacune des branches du système complet.Les premières campagnes de mesures ont permis la validation complète des modèlesA main aspect of this work has been to develop analytical and statistical models of the power efficiency of a time-reversal amplification system (TRAS).It is also important to evaluate the efficiency of a reverberation chamber. This allows quantifying the power received by one or more antenna when the reverberation chamber is excited. This factor is important when considering construction of the most efficient chamber for time-reversal amplification.Measurements assessing the loading effect of antennas in reverberation chambers when the field can be considered diffused were also undertaken. The study focuses on the evaluation of the varying quality factor when adding loaded antennas in the chamber.Another focus of this work is to evaluate the ratios between signals during calibration and focusing phase. An important aspect of the studies presented in this work thus concerns evaluation of the maximum value of the impulse response in a complex propagation system.We also present the power gain of time-reversal techniques and its statistical advantages compared to a classic use of a reverberation chamber.The development of a prototype required the design and implementation of each of the branches of the complete systems.The first measurement campaigns allowed the complete validation of the models
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Izquierdo, Fernández Benjamín. "Electromagnetic propagation in tunnels." Doctoral thesis, Universitat Politècnica de Catalunya, 2011. http://hdl.handle.net/10803/38437.
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Introduction of wireless communications systems in railway communications are at the origin of this thesis. Ifercat, the company in charge of the development of Línia 9 of Barcelona Metro, decided that wireless systems were employed in order to increase efficiency and safety. For this reason, characterisation of ISM 5.8GHz band in tunnel environments for broad band wireless train communications becomes necessary. Tunnel environments constitute harsh environments due to humidity, obstacles, power systems, moving trains, curves¿ The Automatic Train Control system requires a 20MHz bandwidth for train-to-ground video transmission in order to get on-board information and surveillance.
Given that Línia 9 was at the early stages of its development at the beginning of the study, a dual-polarised spectral simulator was developed first. Spectral techniques work in both spatial and spatial-frequency domain and are extremely adaptable to changes in the tunnel cross section as the wave front passes down the tunnel. Efficiency of this technique comes from the well-known properties of FFT algorithms. Spectral techniques provide good near-field predictions and can model different antenna configurations easily. On the other hand, boundary conditions present some issues that must be overcome. Long tunnels also represent a problem in terms of required memory space.
The parabolic equation has been used to enhance the performance of spectral techniques far from the source. They complement each other well because parabolic conditions require smooth variations in one direction, thus far from the source, where only field components propagating parallel to the tunnel axis remain, in order to provide accurate results. Application of Leontovich boundary conditions ensures proper solution at the change of media and its low computational cost permits acceleration of predictions.
These two techniques are then combined to verify the measurement campaigns developed at metro tunnels during the thesis. MIMO schemes are used to enhance the system throughput and simulation predictions are compared to measurements with good results. The work presented in this thesis consisted first on implementing both simulators and verifying their correct behaviour with theoretical analytical solutions. Secondly, predictions are compared with measurement campaigns carried out in Barcelona Metro environments. The study focuses on EM attenuation, field distribution, fading characterisation, antenna location and MIMO processing at the frequency band of interest.
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Haupt, Christian. "Electromagnetic properties of baryons." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=980373271.
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Dimitrakopoulos, Nikolaos. "Electromagnetic MEMS RF Switch." Thesis, University of Leeds, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485179.
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This thesis describes the design, fabrication and test of an electromagne~ically actuated RF MEMS switch. The actuator was fabricated using two different wafers. The first is steel where the coil is been made with a soft magnetic material forming an inner and an outer pole. On the saine wafer the transmission line and'the beam support are present. Silicon has been used as the second wafer to fabricate the mover. The mover consists of the same soft magnetic material as used for the pot core. The switch contact along with the soft magnet is held by a fixed-fixed SU-8 beam. The mover is finally been released from the silicon wafer and dropped on the actuator using the traditio!1al flip chip method. SU-8 which is a negative tone photoresist has been extensively used in this project. .,- Firstly by using standard lithography methods, it has been patterned to form a mould for the coil. Secondly it provides a dielectric as the transmission line is fabricated on top of it. Then it has been used as a mixture with particles of Iron (Fe) and Nickel (Ni). This soft magnetic composite is used for the inner and outer poles of the pot core and also as the magnet that sits on top of the coilto form the mover. Finally SU-8 forms the fixed-fixed beam and its support underneath. In this work there are a number of combinations presented as far as the device is· concerned. There are 28 ~witches accommodated on a 2 inch wafer. The footprint of each .device is 5x4 mm2 mainly due to the beam length. Microstrip and cpw MEMS switches have been fabricated with the latter using both a series and a shunt configuration. The isolation using a 100 J.1m break between the signal lines was measured to be 44.7 dB although the simulated model estimated 54 dBs at 10 GHz. The insertion loss for a cpw series switch was measured to be 0.38 dB at the same frequency. The switching on and off time of the device was measured to be 7 ms and 1 J.1S respectively. The coil requires a 1.2 A current to actuate the mover from a 50 J.1m distance.
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MacLeod, Leesa Marie. "Electromagnetic interference stress testing." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq41465.pdf.
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Parsi, Nikhil. "Electromagnetic effects on soybeans." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/5041.
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Thesis (M.S.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 2, 2008) Includes bibliographical references.
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Lee, Aaron Mark. "Electromagnetic properties of molecules." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243017.
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Still, Benjamin. "T2K ND280 Electromagnetic calorimeter." Thesis, University of Sheffield, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.522357.
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Goudevenos, Apostolos. "Through water electromagnetic communications." Thesis, University of Liverpool, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.494085.
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Underwater communications at high frequencies have a wide variety of applications including diving, military equipment, oil and gas exploration in offshore fields as well as oceanographic mapping. Wireless communications are much more practical than hardwire communications due to the nature of the ocean environment. Currently the most commonly applied method for underwater communications is acoustic communications but have some serious disadvantages. These include low data rate, shadowing and reflections. Optical fibre communications have been offered as a viable alternative but their use is limited to small distances.
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Maguire, Yael G. 1975. "Microslots : scalable electromagnetic instrumentation." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/33677.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2004.Includes bibliographical references (leaves 171-178).
This thesis explores spin manipulation, fabrication techniques and boundary conditions of electromagnetism to bridge the macroscopic and microscopic worlds of biology, chemistry and electronics. This work is centered around the design of a novel electromagnetic device scalable from centimeters to micrometers called a microslot. By creating a small slot in a planarized waveguide called a microstrip, the boundary conditions of the system force an electromagnetic wave to create a concentrated magnetic field around the slot that can be used to detect or produce magnetic fields. By constructing suitable boundary conditions, a detector of electric fields can be produced as well. One of the most important applications of this technology is for Nuclear Magnetic Resonance (NMR). As demonstrated experimentally in this thesis, microslots improves the mass-limited detectability of NMR by orders of magnitude over conventional technology and may move us closer to the dream of NMR on a chip.
(cont.) Improving sensitivity in NMR may lead to a dramatic increase in the rate and accessibility of protein structural information accumulation and a host of other applications for fundamental understanding of biology and biomedical applications, and micro/macroscopic engineering. This microslot structure was constructed at both 6.9mm and 297 [mu]m in order to understand the properties as a function of scale. The 297 [mu]m structure has the best signal to noise ratio of any published planar detector and promises to have higher sensitivity with decreasing size. The detector has been used to analyze water and a relatively simple organic molecule with nanomole sensitivity. 940 picomoles of a small peptide was analyzed and a 2D correlation spectra was obtained which allowed identification of the amino acids in the peptide and could be further used to determine structure. This 297 [mu]m microslot probe was constructed using conventional printed circuit board fabrication and a laser micromachining center. A homebuilt probe was made to house the circuit board. Since this geometry is simpler than previously demonstrated techniques, fabrication can be automated for arrays and is inherently scalable to small sizes (less than 10 [mu]m).
(cont.) The planar nature of the device makes it ideal for integration with microfluidics, transceivers and applications such as cell/neuron chemistry, protein arrays, and HPLC-NMR on pico to nanomoles of sample. Furthermore, this work suggests that a physically scalable, near-field device may have a variety of further uses in integrated circuit chip diagnosis, spintronic devices, nanomanipulation, and magnetic/electric field imaging of surfaces.
by Yael Gregory Eli Maguire.
Ph.D.
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Pressl, Daniel G. (Daniel Gerd). "Investigation of electromagnetic welding." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/53253.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2009.Cataloged from PDF version of thesis.
Includes bibliographical references.
We propose several methodologies to study and optimize the electromagnetic process for Electromagnetic Forming (EMF) and Welding (EMW), thereby lowering the necessary process energy up to a factor of three and lengthening the life-time of EMW compression coils. We present a new theoretical approach to calculate a so-called critical kinetic energy to achieve a proper EMW joint, which is related to the volume of the accelerated mass and the Vicker's Hardness of the material. Using this novel approach, welding windows for several materials are presented. Studying the circuit theory, the current discharge pulse can be optimized to the needs of the EMW process, when opting for a critically damped RLC circuit. We present MultiSIM and MATLAB models that prove the proposed optimization and reflect the experimental EMW setup and parameters. Using the models, unknown parameters, such as machine inductance and resistance can be extrapolated for EMF and EMW machinery. Furthermore, the MATLAB model can calculate the optimal gap between the outer and inner workpiece for the outer workpiece to reach the maximum velocity at impact. Good correlation was found with regards to the High-Speed Videography used to study the EMF process in further detail measuring velocities between 50 m/s and 100 m/s. Studying the mechanical properties of the outer workpiece we propose an EMF-EMW setup that would decrease the strength of the outer workpiece by introducing a controlled amount of wrinkles through an EMF step with a mandrel inside the outer workpiece, followed by a lower critical energy EMW step.
(cont.) Through a failure study, accompanied by a metallurgical analysis, of an Aluminum Bronze Bitter coil we present a materials selection of other possible coil materials, as well as a new method called Electromagnetic Fatigue (EMFA) Analysis to study the crack initiation and propagation in electromagnetic high-current applications. Finally, through two sets of EMW experiments tubular lap joints that were stronger than the base material could be produced and the EMW process parameters of increased cleanliness, gap, wall thickness and a lower taper angle, for the case of our setup, showed to increase the final joint strength.
by Daniel G. Pressl.
Ph.D.
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Flint, James Alan. "Efficient automotive electromagnetic modelling." Thesis, Loughborough University, 2000. https://dspace.lboro.ac.uk/2134/33758.
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The Transmission Line Modelling (TLM) method is applied to the electromagnetic modelling of vehicles. Implications of increasing frequencies in computer models of electromagnetic compatibility (EMC) studies are discussed. Efficient algorithms and resource management strategies are developed With a view to producing accurate results m a realistic computational run time. Theoretical aspects covered are: (1) the development and accuracy of the TLM method; (2) an improved Partial Huygens' surface for plane wave excitation; (3) an evaluation of high-performance local and global absorbing boundary conditions. Implementation aspects of TLM addressed include: (1) the effects of arithmetic precision on link line voltage and stub impedance calculations; (2) the development of an object-oriented computer code using the Object Modelling Technique; (3) methods for estimating and managing the memory requirement and run lime of simulations. It is shown that by optimizing algorithms and carefully managing resources, sufficient improvement can be made to allow relatively sophisticated models to be run on a modest desktop computer.
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Levchenko, A., Світлана Григорівна Золотова, Светлана Григорьевна Золотова, and Svitlana Hryhorivna Zolotova. "Electromagnetic radiation and health." Thesis, Сумський державний університет, 2013. http://essuir.sumdu.edu.ua/handle/123456789/31097.
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Electrical hazards Strong radiation can induce current capable of delivering an electric shock to persons or animals. It can also overload and destroy electrical equipment. The induction of currents by oscillating magnetic fields is also the way in which solar storms disrupt the operation of electrical and electronic systems, causing damage to and even the explosion of power distribution transformers, blackouts (as occurred in 1989), and interference with electromagnetic signals (e.g. radio, TV, and telephone signals).
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/31097
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Chaudhary, Sumeet. "Lightweight Electromagnetic Induction Motor." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1581333548692675.
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Millet, Floyd W. "Improving Electromagnetic Bias Estimates." Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd525.pdf.
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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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Mohajer, Iravani Baharak. "Electromagnetic interference reduction using electromagnetic bandgap structures in packages, enclosures, cavities, and antennas." College Park, Md.: University of Maryland, 2007. http://hdl.handle.net/1903/7669.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2007.Thesis research directed by: Dept. of Electrical and Computer Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Jones, Travis Hamilton. "On the Interactions of Electromagnetic Fields with Human Cells." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587493583447491.
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Berry, Yoke. "The effect of pulsed electromagnetic fields on protein unfolding." Access electronically, 2005. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20060713.142625/index.html.
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Germany, Garrett Ross. "ANALYSIS OF ELECTROMAGNETIC LAUNCHER DESIGN AND MODELING." DigitalCommons@CalPoly, 2016. https://digitalcommons.calpoly.edu/theses/1563.
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This thesis derives working expressions from electromagnetic physical laws to gain a deeper understanding of the nature of railguns. The expressions are refined for ease of use and then compared to electromagnetic simulators that solve complex equations that arise from different rail geometry. Further simplifications lead to an expression for the final velocity of the projectile and showcase the importance of the system resistance to projectile flux gain ratio. A Simulink simulation then incorporates the resulting non-linear differential equations and approximates the projectile velocity over time based on physical dimensions and material properties. Some equations derived can be found in literature regarding the subject but often lack explanation. This work is intended to provide a thorough derivation of all the relative constituent relations between the critical characteristics of the gun such as the strength of the forces acting on the rail and projectile, rail current, and initial velocity of the projectile. This makes it easier to identify what influences acceleration of the projectile, how much bracing each rail needs, how much initial velocity to give the projectile, etc. Design options discussed besides the standard design include the augmented rail system, a magnetic shell design, and a “wrap around” design. The tradeoffs encountered in each design are discussed in length. Due to the lack of a sufficient power source during testing the projectile was unable to travel down the length of the rails due to metal binding, insufficient pulse duration, and too much circuit resistance. It was found that using copper tungsten for the rails ensures that the rails can withstand the arcing inflicted by the kilo-Ampere current along the rails very well compared to other materials. Also, the copper in the tungsten alloy ensures high conductivity while the tungsten provides structural integrity to the rails during arcing between them and the projectile. Frequency response of conductive projectiles is characterized and improvements such as laminated projectiles are suggested as solutions to mitigate eddy currents induced in the projectile and improve performance.
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Naftali, Verena Kashikuka. "Implementation of a reverberation chamber for electro-magnetic compatibility measurements." Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2566.
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Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2017.This research project focuses on the implementation of a Reverberation Chamber (RC) by the transformation of an existing electromagnetically shielded room. The reverberation chamber is a kind of shielded room designed to create a statistically random internal electromagnetic environment. The reverberating environment makes it possible to obtain high field strengths from a relatively low input power. The electric fields in the chamber have to be stirred to achieve a statistically uniform field. The first part of this thesis presents an overview of reverberation chamber principles and preliminary calculations are done: the lowest usable frequency is estimated to be close to 300 MHz from empirical criteria. Modelling of the statistical environment is then presented, where electromagnetic quantities are characterised by probability density functions (Gaussian, Rayleigh and exponential); correlation issues are also presented. Measurements are performed in the frequency range of 800 MHz – 4 GHz, dictated by the antennas available for this research study. An investigation of cable losses is conducted, followed by a discussion on measurement accuracy. Mechanical stirrers are designed and manufactured. Electromechanical components are selected based on the literature study. Measurements are obtained through an automated setup using MATLAB®. To verify that the RC, with its in-house designed mechanical stirrers, is well-operated, the stirring ratio is experimentally determined. After this first test, an exhaustive investigation of probability density functions is conducted, taking into account correlation issues. Measurements show that the quality factor of the chamber is close to 2000 at 3 GHz, and that 60 independent stirrer positions at 4 GHz can be used for statistical analyses. Finally, the uniformity test is performed with an improved accuracy using frequency stirring. In conclusion, the CPUT RC passes the validation procedure according to the IEC 61000-4-21 standard by generating the required field uniformity within the accepted uncertainty level.
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Kimn, Edward Sun. "A parametric finite element analysis study of a lab-scale electromagnetic launcher." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39498.
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The purpose of the study is to better understand the factors that affect melt-wear in the armature-to-rail contact interface of an electromagnetic launcher (EML). In order to investigate the factors, the study uses finite element analysis (FEA) to vary parameters of a lab-scale EML at the Georgia Institute of Technology. FEA is used due to the complex nature of the system, which includes the geometry and various engineering aspects that the EML incorporates. The study focuses on an uncoupled analysis of the structural, electromagnetic (EMAG), thermal, and modal aspects. The reason for the uncoupled analysis was because the system was complex and there were computational limits. Also, by uncoupling the analysis fields, the way the parameters affected melt-wear could be viewed separately. The study varied the geometry of the armature, the stiffness of the rail system (compliance layer), and the material of the armature. The structural analysis was for the initial contact of the rail to the armature and found the von Mises stresses, contact area, and contact pressure. The EMAG analysis found the Lorentz forces in the system based on a current curve used in the lab-scale EML. The thermal analysis consisted of friction heating and Joule heating. The modal analysis was for the unstressed and pre-stressed armature. Based on the study conducted, it was found that aluminum would provide the best speeds due to its lighter mass, but lacked in the thermal resistance area. Tungsten provided the better thermal resistance, but lacked in the potential speed due to its heavier mass.
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Lintz, William A. "Electromagnetic resonances of metallic bodies." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1997. http://handle.dtic.mil/100.2/ADA333440.
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Thesis (M.S. in Electrical Engineering) Naval Postgraduate School, June 1997.Thesis advisors, Richard W. Adler, Jovan E. Lebaric. Includes bibliographical references (p. 45). Also available online.
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Wawrzyniak, Daniel J. "Electromagnetic imaging of axisymmetric scatterers." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1997. http://handle.dtic.mil/100.2/ADA333395.
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Ranlöf, Martin. "Electromagnetic Analysis of Hydroelectric Generators." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-146629.
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Hydropower maintains its position as the most important source of renewable electric energy in the world. The efficiency of large hydropower plants is unsurpassed, and after more than hundred years of development, the technology is mature and highly reliable. While new hydro resources are currently being developed in Asia and South America, most European countries go through a phase of intense refurbishment and upgrading of existing plants. Challenges faced by the hydropower industry include a knowledge transfer to new generations and the adaptation of unit designs to meet new operational requirements. As with all branches of engineering, the use of computerized design tools has revolutionized the art of hydropower plant design and the analysis of its performance. In the present work, modern tools like coupled field-circuit models and semi-analytic permeance models are used to address different aspects of electromagnetic analysis of generators in large hydropower plants. The results include the presentation of a mathematical model that uses concepts from rotating field theory to determine the air-gap flux density waveform in a hydroelectric generator. The model was succesfully used to evaluate armature voltage harmonics and damper bar currents at no-load and load conditions. A second study is concerned with the importance of losses due to rotational fields in core loss calculations. It is found that dynamic and rotational effects typically increase the total core loss estimates with about 28% in large hydroelectric generators. In a third study, linear models for the calculation of salient pole shoe form factors at an arbitrary level of magnetic loading are presented. The effect of the damper winding configuration on the damping capability of salient-pole generators is then evaluated in a separate study. The predicted impact of the coupling between damper cages on adjacent poles on the damping torque production is verified in a set of experiments.
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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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Ullrich, Stefan [Verfasser]. "Electromagnetic Drift Waves / Stefan Ullrich." Greifswald : Universitätsbibliothek Greifswald, 2011. http://d-nb.info/1015149332/34.
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