Dissertations / Theses on the topic 'Eddy currents'
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Belloufi, Messaoud. "Experimental studies of eddy currents." Thesis, Loughborough University, 1990. https://dspace.lboro.ac.uk/2134/12008.
Full textGiguere, Sylvain. "Pulsed eddy-currents for corrosion detection." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq44910.pdf.
Full textOrtiz, Gomez Natalia. "Eddy currents applied to space debris objects." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/415734/.
Full textCase, Russell. "REDUCING EDDY CURRENTS IN HIGH MAGNETIC FIELD ENVIRONMENTS." Master's thesis, University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4305.
Full textM.S.E.E.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering MSEE
Carstensen, Christian. "Eddy currents in windings of switched reluctance machines." Aachen Shaker, 2007. http://d-nb.info/989018482/04.
Full textWilson, Thomas Lawler. "A multi-coil magnetostrictive actuator." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/28243.
Full textCommittee Chair: Zinn, Ben T.; Committee Member: Book, Wayne; Committee Member: Glezer, Ari; Committee Member: Neumeier, Yedidia; Committee Member: Seitzman, Jerry.
Benhama, Abdelkrim. "Investigation of losses in foil windings of inverter fed transformers operating at medium frequencies." Thesis, University of Salford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386448.
Full textOaten, Susan Rosemary. "Assessment of defects in ferromagnetic metals with eddy currents." Thesis, Brunel University, 1989. http://bura.brunel.ac.uk/handle/2438/5310.
Full textFORTALEZA, LEONARDO GOUVEA E. SILVA. "NON-FERROMAGNETIC METALLIC FOREIGN BODY DETECTION BY EDDY CURRENTS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2016. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=28358@1.
Full textCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Projéteis de chumbo (não-ferromagnéticos) são corpos estranhos comuns na prática médica. Métodos convencionais de localização utilizam radiações ionizantes, impondo riscos à saúde e procedimentos que duram várias horas e tipicamente terminam malsucedidos. Mapas de campos magnéticos obtidos não-invasivamente e inocuamente com SQUIDs beneficiam a localização de agulhas metálicas ferromagnéticas, reduzindo o tempo de remoção bem-sucedida de 6 horas para 10 minutos. SQUIDs são os magnetômetros mais sensíveis, entretanto requerem temperaturas criogênicas, levando a altos custos e baixa portabilidade que impedem a difusão do uso clínico. O objetivo é desenvolver um dispositivo para localizar corpos estranhos metálicos não-ferromagnéticos visando remoção cirúrgica, respeitando requerimentos de projeto: alta sensibilidade, inocuidade, não-invasividade, baixo custo, segurança, portabilidade, facilidade de uso e operação em temperatura ambiente. Sensores GMR e GMI são considerados alternativas mais adequadas. Modelos teóricos de eletrodinâmica clássica aplicados às correntes parasitas servem como base. Dois sistemas eletrônicos são desenvolvidos em configuração gradiométrica para remover interferência ambiente, usando elementos sensores GMR e GMI disponíveis comercialmente. O desempenho é obtido com resultados de simulações, provando a capacidade de detecção de níveis esperados de densidade de fluxo magnético para certos raios de projéteis e distâncias. O Sistema GMI é mais qualificado, sua mais alta sensibilidade e melhor resolução favorecem maiores faixas de medição, inocuidade, segurança e facilidade de uso. Os resultados demonstram a viabilidade dos elementos sensores GMI nessa aplicação. Os benefícios de baixo custo, maior portabilidade e segurança facilitam a utilização clínica de técnicas de localização para corpos estranhos metálicos não-ferromagnéticos mais inócuas e efetivas.
Lead projectiles (non-ferromagnetic) are common foreign bodies in the medical practice. Conventional means of location use ionizing radiation, pose health risks and lead to procedures that last several hours, typically ending unsuccessfully. Magnetic field maps obtained non-invasively and innocuously with SQUIDs benefit the location of ferromagnetic metallic needles, reducing the time of successful removal from 6 hours to 10 minutes. SQUIDs are currently the most sensitive magnetometers, however require cryogenic temperatures, leading to high cost and low portability which prevent widespread clinical use. The objective is to design a device for locating non-ferromagnetic metallic foreign bodies for surgical removal, respecting project requirements of: high sensitivity, innocuousness, non-invasiveness, low cost, safety, portability, ease of use and room temperature operation. GMR and GMI sensors are considered as more suitable alternatives. Classical electrodynamics theoretical models applied to eddy currents induction serve as framework. Two electronic location systems are developed in gradiometric configuration to remove environmental interference, using commercially available GMR and GMI sensor elements. System performance is obtained from simulation results, demonstrating the capability of detecting the magnetic flux density levels expected under certain projectile radii and distances. The GMI system is more qualified, as its higher sensitivity and improved resolution favors larger measurement ranges, innocuousness, safety and ease of use. The results prove the viability of using GMI sensor elements in this application. The benefits of lower cost, higher portability and safety facilitate the clinical use of more innocuous and effective location techniques for non-ferromagnetic metallic foreign bodies.
Meuleners, Michael Joseph. "A numerical study of the mesoscale eddy dynamics of the Leeuwin Current system /." Connect to this title, 2005. http://theses.library.uwa.edu.au/adt-WU2007.0134.
Full textPrabhakaran, Pradeep. "Development of electronic instrument for defect measurements with eddy currents /." St. Lucia, Qld, 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17873.pdf.
Full textAli, Raza. "Defect detection using eddy-currents and Hall effect sensor arrays." [Ames, Iowa : Iowa State University], 2007.
Find full textCarstensen, Christian [Verfasser]. "Eddy Currents in Windings of Switched Reluctance Machines / Christian Carstensen." Aachen : Shaker, 2008. http://d-nb.info/1162790768/34.
Full textSmith, M. C. "Factors affecting the eddy currents response around installed aircraft fasteners." Thesis, Cranfield University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309685.
Full textAti, Modafar K. "Calculation of electromagnetic field problems in large electrical machines using the finite element method." Thesis, University of Newcastle Upon Tyne, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238937.
Full textAbbas, Al-Byati N. "The eddy-current damping of synchronous machines with solid cylindrical rotors." Thesis, University of Southampton, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.330125.
Full textAllen, Nancy. "Finite element modelling of eddy currents in nonlinear and moving media." Thesis, University of Bath, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362151.
Full textChumbinho, Rogřio Paulo Antunes. "Kinematics and dynamics of a cyclonic eddy off Pt. Arena, California /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA298587.
Full text"December 1994." Dissertation supervisor(s): R.L. Haney. Includes bibliographical references (p. 75-79). Also available online.
Gupta, D. K. "Transportation of ferromagnetic powder using linear motor devices." Thesis, Loughborough University, 1994. https://dspace.lboro.ac.uk/2134/9219.
Full textТиркусова, Надія Володимирівна, Надежда Владимировна Тыркусова, Nadiia Volodymyrivna Tyrkusova, and Д. О. Варакин. "Разработка алгоритма и программного обеспечения для расчета параметров гидродинамики вихревых потоков." Thesis, Видавництво СумДУ, 2010. http://essuir.sumdu.edu.ua/handle/123456789/4423.
Full textMeuleners, Michael Joseph. "A numerical study of the mesoscale eddy dynamics of the Leeuwin Current system." University of Western Australia. School of Environmental Systems Engineering, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0134.
Full textNalladega, Vijayaraghava. "Design and Development of Scanning Eddy Current Force Microscopy for Characterization of Electrical, Magnetic and Ferroelectric Properties with Nanometer Resolution." University of Dayton / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1249514169.
Full textLippi, Silvio. "Analysis of rotor eddy-current losses in synchronous motors." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022.
Find full textKYROUSI, FOTEINI. "Large eddy simulations of gravity currents over an erodible bed with suspended sediment transport." Doctoral thesis, Università degli Studi di Trieste, 2018. http://hdl.handle.net/11368/2922531.
Full textGravity currents are essentially horizontal flows driven by a density difference with respect to the ambient fluid. Such flows, can trigger the transport of large amounts of sediment resulting in rapid deformations on the bed of rivers and reservoirs, and causing important environmental issues. Despite the importance of such phenomena, the main mechanisms that lead to sediment entrainment in such flows are still poorly understood. In this thesis a coupled hydro-morphodynamic model is presented in order to simulate sediment transport processes induced by the propagation of gravity currents over erodible-beds. The hydrodynamics of the flow is resolved using the LES-COAST model, that employs the large eddy simulation method, and the topological changes due to erosion and deposition are tracked by the level-set method. The coupling between the two models is achieved through the immersed boundary methodology. The resulting hydro-moprhodynamic tool works in parallel environment that makes the simulation of real systems possible. This model is applied to the simulation of the ripple migration problem in order to test its capabilities. The obtained results are compared with data provided by a similar numerical study and indicate that the model is able to capture correctly the hydrodynamics of the sediment-laden flow and the related topological changes. The sediment pick-up induced by gravity currents is initially simulated assuming stationary flow boundaries and the numerical results are validated by experimental data. The numerical setting considered in this case allows to identify the region of the flow with higher erosive capacity and determine the flow features which play a dominant role on the sediment entrainment. Moreover, the effect of the suspended sediment on the stability condition of the gravity current is examined, along with the influence of the latest on the suspended sediment distribution. Finally, the developed hydro-morphodynamic model is used to simulate the bed forms generated by such flows. It is worth-noting that the propagation of highly erosive gravity currents over loose beds can lead to considerable bed deformation that significantly influence the flow dynamics. For the first time, 3D numerical simulations of gravity currents flowing over a deformable beds are performed. The instantaneous evolution of the generated scour and deposition patterns is presented providing a better insight on the flow-sediment and flow-bed interaction in buoyancy driven flows.
Gromov, Andrey. "Impedance of Soft Magnetic Multilayers : Application to GHz Thin Film Inductors." Doctoral thesis, Stockholm, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3135.
Full textSkutt, Glenn R. "High-Frequency Dimensional Effects in Ferrite-Core Magnetic Devices." Diss., Virginia Tech, 1996. http://hdl.handle.net/10919/30596.
Full textPh. D.
Heger, Walter. "Using the finite difference and the finite element method to solve an electric current diffusion problem." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66150.
Full textSorger, Luís Gonçalo Lourenço. "Characterization of processed materials by electrical currents: development of equipment and applications." Master's thesis, Faculdade de Ciências e Tecnologia, 2014. http://hdl.handle.net/10362/12180.
Full textStructural characterization of welded or processed materials is critical for a correct assessment of their properties. Microstructural analysis by optical microscopy provides information to identify the distinctive zones, their extent and the major transformations induced. For structural analysis, hardness is the simplest property to measure, providing information on the existence of ductile or brittle zones in the material. Furthermore, it can be qualitatively correlated to yield strength. However, these techniques are time consuming and destructive and, therefore, there is need for new, dedicated, preferably non-destructive, characterization methods. The same changes in properties and structure, due to welding and processing, also alter the electrical conductivity of materials. In fact, studies have demonstrated a relation between microstructure and conductivity of friction stir processed Al alloys, relating decreases in this property to the increase in the barriers to electron mobility due to the refined grain of the dynamically recrystallized zone, while the opposite occurs in heat affected zones were grain growth exists. The aim of this thesis was to apply eddy currents electrical conductivity characterization techniques to a wider range of materials, and develop equipment for an alternative electrical current evaluation method, namely, four-point probe potential drop measurements. A prototype for an automated four-point probe electrical conductivity characterization equipment was designed, built and successfully tested. Electrical conductivity characterization techniques, by eddy currents, have been applied to different metallic materials(AISI 1020, AISI 304, AZ31, Ti Grade 5, Ti Grade 2, Lead and Copper) processed by solid-state (Friction Stir Processing (FSP)) and fusion (Metal Active Gas (MAG) and Tungsten Inhert Gas (TIG)) to evaluate the effects on their electrical conductivity profiles and compare them with the hardness profiles and the microstructural features. Results show that the electrical conductivity variations that occur due to welding and processing can be related to the hardness and the microstructure of materials and, depending on the material, this relation can be direct or inverse.
OLIVO, MATTEO. "Efficient Methods for the Study of Eddy-Currents Effects in Medium-Voltage Rotating Electrical Machines." Doctoral thesis, Università degli Studi di Trieste, 2020. http://hdl.handle.net/11368/2960316.
Full textThe efficient computation of eddy-current effects in medium voltage electric machines is discussed in this dissertation. Two particular cases are considered. Firstly, the effects of shaft eddy-currents on two-pole induction motor performance is addressed, with special focus on the power factor. In the second part of the thesis the start-up calculation of a large synchronous motor with solid rotor is analyzed. For each application a special calculation procedure is introduced. These procedures adopt a set of suitable finite-element models to properly compute the machine equivalent circuit parameters that are mainly influenced by eddy-current-related phenomena. By suitably choosing finite-element models boundary conditions and excitations their geometry is simplified to the maximum possible extent, in order to reduce the computational burden. The results of the new calculation methods are compared with experimental data and with analogous results obtained from commonly-adopted calculation procedures. The comparison proves that the proposed approaches can lead to high accuracy levels with very remarkable computational savings.
Jones, Travis Hamilton. "Analysis and Optimization of Eddy Current Detection in Animal Tissue." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1398919426.
Full textChen, Chen. "Simulation, design and experimental validation of a passive magnetic damper for ultra-fast actuators." Thesis, KTH, Elektroteknisk teori och konstruktion, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-153639.
Full textДенисов, Станіслав Іванович, Станислав Иванович Денисов, Stanislav Ivanovych Denysov, Ганна Валеріївна Бабич, Анна Валерьевна Бабич, Hanna Valeriivna Babych, Людмила Анатоліївна Денисова, Людмила Анатольевна Денисова, Liudmyla Anatoliivna Denysova, and Ye A. Peredriy. "Effective Landau-Lifshitz-Gilbert Equation for a Conducting Nanoparticle." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35362.
Full textFoley, Brian M. "A System for Detecting the Position of a Molten Aluminum Metal-Front within a Precision Sand Mold." Digital WPI, 2009. https://digitalcommons.wpi.edu/etd-theses/50.
Full textRibbenfjärd, David. "A lumped element transformer model including core losses and winding impedances." Licentiate thesis, KTH, School of Electrical Engineering (EES), 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4307.
Full textIn order to design a power transformer it is important to understand its internal electromagnetic behaviour. That can be obtained by measurements on physical transformers, analytical expressions and computer simulations. One benefit with simulations is that the transformer can be studied before it is built physically and that the consequences of changing dimensions and parameters easily can be tested.
In this thesis a time-domain transformer model is presented. The model includes core losses as magnetic static hysteresis, eddy current and excess eddy current losses. Moreover, the model comprises winding losses including eddy currents, capacitive effects and leakage flux. The core and windings are first modelled separately and then connected together in a total transformer model. This results in a detailed transformer model.
One important result of the thesis is the possibility to simulate dynamic hysteresis including the eddy current shielding in the magnetic core material. This is achieved by using Cauer circuit combined with analytical expression for static and dynamic hysteresis. Thereby, all magnetic loss components in the material can be simulated accurately. This dynamic hysteresis model is verified through experiments showing very good agreement.
Almelah, Rema Bashir. "Ekman currents caused by variable wind in models of upper ocean with depth and time dependent eddy viscosity." Thesis, Keele University, 2018. http://eprints.keele.ac.uk/5601/.
Full textKoivula, A. (Antero). "Magnetic resonance image distortions due to artificial macroscopic objects:an example: correction of image distortion caused by an artificial hip prosthesis." Doctoral thesis, University of Oulu, 2002. http://urn.fi/urn:isbn:951426827X.
Full textPinchuk, Amy Ruth. "Spectrally correct finite element analysis of electromagnetic fields." Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=75780.
Full textSpurious components in solutions to vector field problems are shown to corrupt deterministic solutions. These corruptions are identifiable with spurious modes familiar to high frequency modal analysis. Spectrally correct mixed order finite elements are demonstrated to retrieve accuracy in deterministic analyses.
The formulation may be limited by computer round-off at matrix assembly which affects the solenoidality of vector fields. Furthermore, extreme values encountered in low frequency eddy current analysis lead to ill conditioning and unreliable solutions. These numerical instabilities are overcome by parametric adjustment of permittivities. Error estimates are established to monitor inaccuracies introduced by permittivity adjustment.
Girardon, Hugo. "Shape reconstruction of deposits inside a steam generator using eddy current measurements." Thesis, Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAX086.
Full textNon-destructive testing is an essential tool to assess the safety of the facilities within nuclear power plants. In particular, conductive deposits on U-tubes in steam generators constitute a safety issue as they may block the cooling loop. To detect these deposits, eddy-current probes are introduced inside the U-tubes to generate currents and measuring back an impedance signal. We develop a shape optimization technique with regularized gradient descent to invert these measurements and recover the deposit shape. To deal with the unknown geometry, and its possibly complex topological nature, we propose to model it using a level set function.The methodology is first validated on synthetic axisymmetric configurations and fast convergence is ensured by careful adaptation of the gradient steps and regularization parameters. Using the actual domain, from which the acquisitions are made, we then consider a more realistic modeling that incorporates the support plate and the presence of imperfections on the tube interior section. We employ in particular an asymptotic model to take into account these imperfections and treat them as additional unknowns in our inverse problem. A multi-objective optimization strategy, based on the use of different operating frequencies, is then developed to solve this problem. We present various numerical examples with synthetic and experimental data showing the viability of our approach.The focus is then placed on the transposition of the 2D-axisymmetric work to more generic 3D configurations. Solving Maxwell eddy-current equations in 3D raises modeling issues related to the choice of the problem formulation as well as high computational costs that need to be reduced before discussing the reconstruction algorithm. Using the knowledge acquired with 2D-axisymmetric reconstruction, an efficient inversion strategy is then proposed and implemented on 3D synthetic data. Validating numerical examples demonstrate the feasibility of the inversion even for large data at a relatively moderate cost and with good accuracy and robustness with respect to noise and modeling errors
Marcusson, Birger. "Magnetic Leakage Fields and End Region Eddy Current Power Losses in Synchronous Generators." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-331182.
Full textKruse, Denise M. "Large eddy simulation of interactions between free convection, wind driven currents, and baroclinicity in Labrador Sea deep mixed layers." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2000. http://handle.dtic.mil/100.2/ADA380272.
Full textThesis advisor(s): Guest, Peter ; Harcourt, Ramsey. "June 2000." Includes bibliographical references (p. 91-92). Also available online.
Mouton, Zac. "Modelling and design of an eddy current coupling for slip-synchronous permanent magnet wind generators." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/80114.
Full textENGLISH ABSTRACT: Slip-synchronous permanent magnet generators (SS-PMG) is a recently proposed direct-grid connected direct-drive generator topology for wind power applications. It combines a permanent magnet synchronous generator and a slip permanent magnet generator through a common permanent magnet rotor. In this study the possibility of using an eddy current coupling as the slip permanent magnet generator is investigated. The eddy current coupling has the attractive advantage of completely removing cogging and load torque ripple, which are known problems in the SS-PMG. However, the analytical modelling of the eddy current coupling is complex. Three different topologies are considered for the eddy current coupling. A finite element model is presented for the eddy current coupling. It is shown that 2D finite element methods are inaccurate compared to 3D finite element methods when solving eddy currents in eddy current couplings. In order to test the accuracy of the finite element modelling of a large eddy current coupling a prototype slip rotor is designed to operate with an existing permanent magnet rotor. Two topologies are optimally designed and compared for the slip rotor, using 3D finite element transient simulations. One of the designed topologies is used for the construction of the prototype slip rotor. The manufactured eddy current coupling allows for comparison between the 3D finite element simulations and measured results, which shows an excellent correlation. Based on observations of the 3D finite element simulations an analytical approximation of the eddy current coupling is proposed for low slip frequencies. It is shown that the analytical model is very dependent on the accurate modelling of the eddy current paths in the slip rotor, something that is difficult to determine accurately. An approximation is made, again based on 3D finite element simulations, which allows the accurate modelling of the current paths for different axial lengths. The analytical model is used for rapid design optimisation of both the slip rotor and permanent magnet rotor of the eddy current coupling, for two different eddy current coupling topologies. The optimised eddy current coupling design with the best results is compared to existing slip permanent magnet generator technologies. The eddy current coupling is shown to have the potential to be a feasible alternative to existing slip permanent magnet generator topologies for application in slip-synchronous permanent magnet generators. It has excellent torque versus slip behaviour, and no cogging or load torque ripple. However, the manufacturing and assembly process of the proposed slip rotor has to be improved for the eddy current coupling to be a realistic competitor to the existing slip permanent magnet generator technologies.
AFRIKAANSE OPSOMMING: Die glip-sinkroon permanente magneet generator is ʼn direk-aangedrewe wind generator wat direk aan die krag netwerk gekoppel kan word. Dit kombineer ʼn permanente magneet sinkroon generator en ʼn permanente magneet glip generator deur middel van ʼn gemeenskaplike permanente magneet rotor. In hierdie studie word die moontlike gebruik van ʼn werwelstroom skakel as plaasvervanger vir die permanente magneet glip generator ondersoek. Die werwelstroom skakel het geen vertandings of las draaimoment rimpeling nie, wat bekende probleme vir die glip-sinkroon permanente magneet generator is. Die analitiese modellering van die werwelstroom skakel is egter nie eenvoudig nie. Daar word drie verskillende topologieë oorweeg vir die werwelstroom skakel. ʼn Eindige element model word ontwikkel vir die werwelstroom skakel. Dit word bevind dat 2D eindige element analise onvoldoende is vir die berekening van werwelstrome in die werwelstroom skakel, en gevolglik word 3D eindige element modelle gebruik in hierdie studie. Om die akkuraatheid van die eindige element model te beproef word ʼn prototipe glip rotor optimaal ontwerp deur middel van eindige element analise. Die glip rotor vorm saam met ʼn bestaande permanente magneet rotor ʼn werwelstroom skakel. Vir hierdie ontwerp word twee werwelstroom skakel topologieë gebruik, en met mekaar vergelyk. Die topologie wat beter presteer word gebruik vir die vervaardiging van die glip rotor. ʼn Vergelyking van die gemete waardes van die vervaardigde werwelstroom skakel en die resultate van die 3D eindige element simulasies dui daarop dat die 3D eindige element modellering ʼn baie goeie voorspelling van die werklikheid is. ʼn Analitiese model vir die werwelstroom skakel onder lae glip toestande is ontwikkel deur gebruik te maak van observasies uit die 3D eindige element simulasies. Die analitiese model is baie afhangklik van die modellering van die werwelstrome se stroompaaie, iets wat moeilik is om akkuraat te bepaal. ʼn Benadering word gemaak wat die akkurate modulering van die stroompaaie moontlik maak vir verskillende aksiale lengtes. Die analitiese model word dan gebruik vir vinnige optimering van die werwelstroom skakel se ontwerp vir twee verskillende werwelstroom skakel topologieë. Die geoptimeerde ontwerp wat die beste resultate toon word vergelyk met bestaande permanente magneet glip generators. Dit word gewys dat die werwelstroom skakel die potensiaal het om ʼn uitvoerbare alternatief tot die permanente magneet glip generator te wees, vir gebruik in glip-sinkroon permanente magneet generators. Die werwelstroom skakel toon baie goeie draaimoment teenoor glip gedrag, en het geen vertandings of las draaimoment rimpeling nie. Voordat die werwelstroom generator ʼn realistiese kompeteerder teenoor die bestaande glip-sinkroon tegnologie is, moet daar verbeterde vervaardigings maniere gevind word vir die voorgestelde glip rotor.
McFerran, Jennifer. "An Electromagnetic Method for Cancer Detection." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1253558341.
Full textPipis, Konstantinos. "Eddy-current testing modeling of axisymmetric pieces with discontinuities along the axis by means of an integral equation approach." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS176/document.
Full textNondestructive Testing (NDT) of parts for industrial applications such as in nuclear and aeronautical industry has led to the need for fast and precise models. Such models are useful for the development of the inspection methods, the optimisation of probes, the evaluation of the Probability of Detection (POD) curves or for the flaw characterisation.This PhD thesis focuses on the eddy-current NDT of layered cylindrical pieces with discontinuities in the z direction and containing a narrow crack. A model for the inspection of such pieces is developed in order to be applied on the inspection of fastener holes met in aeronautics and of steam generator tubes in nuclear sector.The model is based on an integral equation formalism. More precisely, for the calculation of the impedance change one needs to solve an integral equation over the surface of the narrow crack, which is represented by a surface electric dipole distribution. This is the method known as surface integration method (SIM). This formulation requires, on the one hand, the calculation of the electric field in the absence of the flaw, the so-called primary field, and, on the other hand, the Green's function expression corresponding to the geometry of the flawless piece. Both electromagnetic problems are solved by means of the Truncation Region Eigenfunction Expansion (TREE) method. The TREE method is a powerful tool for the solution of electromagnetic problems which uses the rapid decrease of the field in order to truncate the region of interest at a distance where the field is negligible.The model is validated by comparing the results of the coil impedance variation with those obtained by an approach that combines the volume integral method (VIM) with SIM, known as VIM-SIM method, implemented in the commercial software CIVA and the finite element method (FEM) implementation in COMSOL software. Three different configurations have treated. The more general geometry of a conducting half-space with a borehole, a conducting plate with a borehole and a crack and a conducting semi-infinite tube with a crack near the edge. The results of the three models show good agreement between them. The computational time of the SIM model is significantly lower compared to previous models. Furthermore, another advantage of the SIM model is that it provides the possibility of a scan inside the borehole
Båvall, Lennart. "A measurement approach to determination of coating thickness with eddy currents and to a capacitive person detector for robot safety /." Linköping : Univ, 2004. http://www.bibl.liu.se/liupubl/disp/disp2004/tek843s.pdf.
Full textWalker, Rachel. "Large-eddy Simulation of the Inner Continental Shelf Under the Combined Effects of Surface Temperature Fluxes, Tidal Currents and Langmuir Circulation." Scholar Commons, 2015. https://scholarcommons.usf.edu/etd/5590.
Full textCombes, Vincent. "Upwelling and cross-shelf transport dynamics along the Pacific Eastern Boundary." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34814.
Full textOscarsson, Mattias. "Modelling and design approaches of magnetostrictive actuators." Licentiate thesis, Stockholm : Kungliga Tekniska högskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4435.
Full textAkuetevi, Cataria Quam Cyrille. "Dynamics of turbulent western boundary currents at low latitudes, a numerical study." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENU002/document.
Full textStrong western boundary currents are one of dominant features of the world oceans, also at low latitudes. They exhibit a turbulent dynamics and their region is a source of strong kinetic energy production and internal variability of the worlds oceans. Several places exists where the western boundary currents retrofect (i.e separation from the coast) and generate coherent structures as anticyclonic eddies, bursts and dipoles. The dynamics of turbulent western boundary currents has so far not been extensively studied in the viewpoint of turbulent boundary-layer theory. The approach followed in this thesis is to use a fine resolution (2.5km) reduced-gravity shallow water model to understand the turbulent boundary-layer processes and then apply these findings to the Ocean General Circulation Model NEMO in the Drakkar configuration (~10km). The case of the Somali Currentis considered for this application
Sun, Xin. "Flow characteristics in compound channels with and without vegetation." Thesis, Loughborough University, 2007. https://dspace.lboro.ac.uk/2134/7992.
Full textWills, Dominic. "Methods to quantify and reduce rotor losses in a solid rotor yoke permanent magnet machine." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4014.
Full textENGLISH ABSTRACT: Certain types of electric machines are particularly susceptible to the proliferation of eddy currents flowing within the solid conducting regions in the rotor. Single-layer, non-overlapping windings within uneven open slots are some stator properties that can produce damaging, asynchronous magnetic field harmonics which manifest in the rotor as eddy currents. The ohmic losses caused by these eddy currents are a source of inefficiency and can cause a marked increase in the temperature of the rotor. This temperature rise can be dangerous for the magnets, which have to be kept within temperature limits to avoid partial or full demagnetization. The research work presented here is concerned with reducing the effect of eddy currents in the rotor magnets and solid rotor yoke of an electric machine. The work presents analytical methods to calculate the magnetic fields, eddy currents and solid loss in an electric machine due to current in the winding and due to the interaction of the permeance variation in the stator with the magnets in the rotor. A method is also suggested where the analytical theory can be used with a magnetostatic finite element solution to produce a transient solid loss result. The research work also investigates a method for optimal segmentation in both level and penetration, and provides some design suggestions. The work presents the method of partial magnet segmentation, which is a technique whereby thin incisions are made into the magnet material from one or both sides. Another method of partial rotor segmentation is also presented where the incisions are made into a portion of the magnet-facing solid yoke. These methods attempt to interrupt the flow of eddy currents and increase the resistance ‘seen’ by the eddy currents, while also keeping construction difficulty and cost to a minimum. The methods are verified using finite element calculations which are compared to measured results. The result is that partial magnet segmentation is a very useful, effective and practical method of segmenting magnets. The loss reduction profile can be similar to that of traditional full segmentation. The method of partial rotor segmentation also shows a large reduction in rotor power loss. With implementation of these methods on a test machine, one can expect an efficiency increase of more than 4 %
AFRIKAANSE OPSOMMING: Sekere tipes van elektriese masjiene is veral sensitief vir die vloei van werwelstrome in solied geleidende gebiede in die rotor. Enkellaag, nie-oorvleuelende wikkelings in oneweredige oop gleuwe is enkele stator eienskappe wat skadelike, asinchrone magneetveld harmonieke tot gevolg kan hê, wat as werwelstrome in die rotor manifesteer. Die ohmiese verliese wat deur hierdie werwelstrome teweeg gebring word is 'n bron van ondoeltreffendheid en kan lei tot 'n merkbare toename in die temperatuur van die rotor. Hierdie temperatuur styging hou gevaar in vir die magnete en moet binne temperatuur limiete gehou word om gedeeltlike of self volle demagnetisering te vermy. Die navorsing vervat in hierdie document is gemoeid met die vermindering van die effek van werwelstrome in die rotor magnete en in die soliede rotor juk van 'n elektriese masjien. Die werk bied analitiese metodes aan vir die berekening van die magneetvelde, werwelstrome en soliede verliese in ’n elektriese masjien as gevolg van strome in die wikkelings en die interaksie van die permeansie variasie van die stator met die magnete in die rotor. ’n Metode word ook voorgestel waar die analitiese teorie saam met ’n magnetostatiese eindige element oplossing gebruik word om ’n resultaat vir die oorgang soliede verliese te verkry. Die navorsingswerk ondersoek ook ’n metode vir die optimale segmentering in beide vlak sowel as penetrasie, en verskaf sekere ontwerp voorstelle. Die werk bied die metode aan van gedeeltelike magneet segmentering, wat 'n tegniek is waarvolgens dun insnydings gemaak word aan een of beide kante van die magneet materiaal. Nog ’n metode van gedeeltelike rotor segmentering word beskou waar die insnydings in in ’n gedeelte aan die magneetkant van die soliede rotor juk gemaak word. Hierdie metodes poog om die vloei van werwelstrome te onderbreek en die weerstand soos "gesien" deur die werwelstrome te verhoog, terwyl konstruksie kompleksiteit en koste tot ’n minimum beperk word. Die metodes word bevestig deur eindige element berekeninge wat met gemete resultate vergelyk word. Die gevolg is dat gedeeltelike magneet segmentering 'n baie nuttige, doeltreffende en praktiese metode van die segmentering van magnete is. Die verliesverminderingsprofiel van gedeeltelike segmentering kan soortgelyk wees aan dit van tradisionele volle segmentering. Die metode van gedeeltelike rotor segmentering toon ook 'n groot afname in rotor drywingsverlies. Met die implementering van hierdie metodes op ’n toetsmasjien, kan ’n mens ’n verhoging in benuttingsgraad verwag van meer as 4 %