Dissertations / Theses on the topic 'Magnetic current'
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Raimbault, Nathaniel. "Gauge-invariant magnetic properties from the current." Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30179/document.
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De nombreux phénomènes physiques ne peuvent être compris qu'en s'intéressant à la structure électronique. Cette dernière peut être interprétée en termes de propriétés électromagnétiques, chacune de ces propriétés révélant diverses informations sur le système étudié. Il est donc important d'avoir des outils efficaces afin de calculer de telles propriétés. C'est dans ce contexte que cette thèse a été écrite, notre principal objectif ayant été de développer une méthode générale donnant accès à une vaste gamme de propriétés électromagnétiques. Dans la première partie de cette thèse, nous décrivons le socle théorique au sein duquel nous travaillons, en particulier la théorie de la fonctionnelle de la densité de courant dépendante du temps (TDCDFT), qui est une approche qui permet de décrire la réponse du système à un champ magnétique. La seconde partie est consacrée à la méthode que nous avons mise au point pour calculer diverses propriétés magnétiques en préservant l'invariance de jauge. Nous démontrons en particulier qu'en utilisant une simple règle de somme, il est possible de placer les courants diamagnétique et paramagnétique sur un pied d'égalité, évitant par là même les écueils habituels intrinsèques au calcul de propriétés magnétiques, comme la dépendance en l'origine de la jauge du vecteur potentiel. Nous illustrons notre méthode en l'appliquant notamment au calcul de la magnétisabilité et du dichroïsme circulaire, qui est une propriété possédant d'importantes applications pratiques, notamment en biologie. Dans la dernière partie, plus exploratoire, nous tentons d'étendre notre formalisme aux systèmes périodiques. Nous y discutons plusieurs stratégies afin de calculer l'aimantation dans des systèmes décrits par des conditions aux limites périodiquesVarious phenomena of matter can only be understood by probing its electronic structure. The latter can be interpreted in terms of electromagnetic properties, each property revealing a different piece of information. Having a reliable method to calculate such properties is thus of great importance. This thesis is to be regarded in this context. Our main goal was to develop a general method that gives access to a wide variety of electromagnetic properties. In the first part of this thesis, we describe the theoretical background with which we work, and in particular time-dependent current-density-functional theory (TDCDFT), which is a density-functional approach that can describe the response due to a magnetic field. The second part is dedicated to the method we developed in order to calculate various magnetic properties in a gauge-invariant manner. In particular, we show that by using a simple sum rule, we can put the diamagnetic and paramagnetic currents on equal footing. We thus avoid the usual problems that arise when calculating magnetic properties, such as the dependence on the gauge origin of the vector potential. We illustrate our method by applying it to the calculation of magnetizabilities and circular dichroism, which has important applications, notably in biology. In the last part, which is more explorative, we aim at extending our formalism to periodic systems. We discuss several strategies to calculate magnetization in systems described with periodic boundary conditions
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Ersoz, Ali. "Magnetic Resonance Current Density Imaging Using One Component Of Magnetic Flux Density." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612164/index.pdf.
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Magnetic Resonance Electrical Impedance Tomography (MREIT) algorithms using current density distribution have been proposed in the literature. The current density distribution can be determined by using Magnetic Resonance Current Density Imaging (MRCDI) technique. In MRCDI technique, all three components of magnetic flux density should be measured. Hence, object should be rotated inside the magnet which is not trivial even for small size objects and remains as a strong limitation to clinical applicability of the technique. In this thesis, 2D MRCDI problem is investigated in detail and an analytical relation is found between Bz, Jx and Jy. This study makes it easy to understand the behavior of Bz due to changes in Jx and Jy. Furthermore, a novel 2D MRCDI reconstruction algorithm using one component of B is proposed. Iterative FT-MRCDI algorithm is also implemented. The algorithms are tested with simulation and experimental models. In simulations, error in the reconstructed current density changes between 0.27% - 23.00% using the proposed algorithm and 7.41% - 37.45% using the iterative FT-MRCDI algorithm for various SNR levels. The proposed algorithm is superior to the iterative FT-MRCDI algorithm in reconstruction time comparison. In experimental models, the classical MRCDI algorithm has the best reconstruction performance when the algorithms are compared by evaluating the reconstructed current density images perceptually. However, the J-substitution algorithm reconstructs the best conductivity image by using J obtained from the proposed algorithm. Finally, the iterative FT-MRCDI algorithm shows the best performance when the reconstructed current density images are verified by using divergence theorem.
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Eriksson, Oscar, and Kaj Dahl. "Magnetic Monopole Current in Artificial Square Spin Ice." Thesis, KTH, Skolan för teknikvetenskap (SCI), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-154229.
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Recent theoretical and experimental results have revealed the existence of magnetic monopoles, in the form of quasi particles, in both condensed matter known as spin ice, as well as in two-dimensional artificial versions of the same material. In this report a two-dimensional Ising model is first examined, then an artificial square spin ice model using a dipole approximation, only taking into account nearest and next nearest neighbors. The Metropolis algorithm is used to obtain the internal energy, specific heat capacity and entropy as functions of temperature. In the latter model the magnetic monopole concentration and monopole current is also simulated. The two models show similar quantitative behavior in the above mentioned physical quantities, and in comparison to previously published results. In the artificial square spin ice model, under the influence of a magnetic field, a rapidly decreasing monopole current is observed, which decreases faster for higher temperatures. The magnitude of the magnetic field plays a significant role in the generation of the monopole current, and no direct effect of the phase transitionis observed.Nya teoretiska och experimentella resultat har uppvisat förekomsten av magnetiska monopoler, i form av kvasi-partiklar, både i kondenserade material kallade spinn-is, och i tvådimensionella artificiella versioner av samma material. I den här rapporten undersöks först en tvådimensionell Isingmodell, därefter en artificiell kvadratisk spinn-is-modell med hjälpav en dipolapproximation, där hänsyn endast tas till närmaste och näst närmaste grannar. Metropolis-algoritmen används för beräkna energi, specifika värmekapaciteten och entropinsom funktioner av temperatur. I den senare modellen simuleras även monopolskoncentrationen och monopolsströmmen. De två modellerna uppvisar snarlikt kvantitativt beteende med avseende på ovan nämnda fysikaliska storheter, jämfört med varandra och tidigare publicerade resultat. Under inverkan av ett magnetfält observeras en snabbt avtagande monopolsström, i den artificiella kvadratiska spinn-is-modellen, som avtar snabbare med högre temperaturer. Storleken på det pålagda magnetfältet har markant betydelse för alstrande av monopolsströmmen, och ingen direkt effekt av fasövergången observeras.
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Wang, Margaret Hsin-Yi 1978. "Study of current measurement in magnetic force microscopy." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/87296.
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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.Includes bibliographical references (p. 137-140).
by Margaret Hsin-Yi Wang.
M.Eng.
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Watson, Joseph Conrad. "Eddy current detection of magnetic and non-magnetic metallic edges beneath continuous plate." Thesis, Brunel University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394797.
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Girlevicius, Lukas. "Active magnetic bearing driver circuit design featuring current measurement integration." Thesis, Uppsala universitet, Elektricitetslära, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-269215.
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Researchers at Uppsala University are developing a flywheel energy storage device intended to be used in electrical vehicles. Kinetic energy storage technology has potential to make purely electric powertrain both more effective and efficient. While deployment of the third prototype is approaching there has been a request for a more precise and noise-immune circuitry to power active magnetic bearings that hold and stabilise the rotor. A similar circuit designed for powering electromagnets was recently developed at the Uppsala University’s Electricity department and is used as a template in development of the new active magnetic bearing driver circuit. Current measurement integration technique is tested and implemented as a way to increase circuit’s control feedback loop performance. To further boost precision and noise-immunity 0-20 mA current loop signals are adapted as the standard for output signals. Results of this project include a thorough analysis of the electromagnet driver circuit development, implementation of a new current sensing technique including an experimental self-inductance measurement, printed circuit board layout design and a full list of components necessary to power and control two sets of active magnetic bearings consisting of 8 individual electromagnets.
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Xu, Ming. "Critical current density and time-dependent magnetization of the high transition temperature superconductors." Diss., Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/30033.
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Fang, Dong. "Current-induced torque driven ferromagnetic resonance in magnetic microstructures." Thesis, University of Cambridge, 2011. https://www.repository.cam.ac.uk/handle/1810/241302.
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This Dissertation explores the interaction between the magnetisation and an alternating current in a uniform ferromagnetic system. Diluted magnetic semiconductors (Ga,Mn)As and (Ga,Mn)(As,P) have been studied. Due to their strong spin-orbit coupling and well-understood band-structure, these materials are well-suited to this investigation. The combined effect of spinorbit coupling and exchange interaction permits the alternating current to induce an oscillating current-induced torque (CIT) on the magnetisation. In the frequency range close to the natural resonance frequency of the magnetic moments (gigahertz), CIT can excite precessional motion of the magnetisation, a process known as ferromagnetic resonance (FMR). CIT can be parameterised by an effective magnetic field. By analysing the lineshape of the measured FMR signals, the magnitude and orientation of this effective field have been accurately determined. Moreover, the current-induced fields in these ferromagnetic materials have been observed with symmetries of the Dresselhaus, and for the first time, Rashba spin-orbit coupling. A new class of device-scale FMR technique, named as CIT-FMR, has been established in this Dissertation, with the advantage of simple device structure (only a resistor is required) and scalability (measurements have been performed on devices sized from 4 μm down to 80 nm). This technique is not only limited to magnetic semiconductors, but can also be transferred to study other ferromagnetic systems such as ultrathin metal films. Finally, the CIT-FMR technique is employed to study the magnetic anisotropyin individual (Ga,Mn)As and (Ga,Mn)(As,P) micro-devices. Devices down to 80 nm in width have been measured in (Ga,Mn)(As,P), which show strong strain-relaxation-induced anisotropy, larger than any previously reported cases on (Ga,Mn)As. Furthermore, due to the tensile-strain on the (Ga,Mn)(As,P) epilayers, the anisotropy field due to patterning-induced strain-relaxation in these devices is observed to take the opposite direction compared to that in the compressively-strained (Ga,Mn)As samples.
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Lillington, Mark Andrew Edwin. "Current-density maps and the magnetic criterion of aromaticity." Thesis, University of Sheffield, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.487604.
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On the magnetic criterion, an aromatic system is one that sustains a diatropic ring current. Once this definition is accepted, calculation of current density induced in a molecule by an external magnetic field gives a direct way of determining aromaticity from ab initio calculation. The ipsocentric treatment of molecular magnetic response, in which each point is the origin for the local current-density, offers an accurate, economical and conceptually transparent approach to the calculation of ring currents. The distribution of origin uniquely leads to physically non-redundant orbital contributions· that can be used to interpret (or predict) currents in terms of orbital symmetries, energies and nodal character. Diatropic and paratropic currents obey translational and rotational selection rules, respectively, leading to a 'spectroscopic', 'frontier-orbital' theory of ring currents and magnetic aromaticity. This thesis reports investigations of the nature and origin of ring currents in 1t-, (j- and homo-aromatic systems. Rules developed for annulenes extend to heterocycles and account for retention of ring-current aromaticity in perfluorobenzenes in which argon atoms are progressively inserted in the CF bonds. Currents in benzenoid and nonbenzenoid polycyclic aromatic hydrocarbons give varied patterns which can be rationalised in terms of Kekule structures and Pauling bond orders. These concepts are used to explain rim-and-hub currents in circulenes and design molecules with fully paramagnetic 1t currents, verified by ab initio calculation. Studies of heteropolycycles with carbocyclic cores demonstrate the aromaticity of mellitic trianhydride, the non-aromaticity of 'quasi-rings' closed by hydrogen- and lithium-bonds, and rationalise the magnetic properties of the new 'sulflowers' . Calculations on model rings of silicon atoms with tangential p-p bonding show the possibility of (j ring currents governed by modified versions of the ipsocentric 1t selection rules. Saturated cyclopropane also supports (j ring current. The homotropylium cation illustrates the association of a ring current of modified topology with homoaromaticity.
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Keller, Lisa A. "Current-mode control of a magnetic amplifier post regulator." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-02132009-171329/.
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Kyte, David John. "Magnetic induction tomography and techniques for eddy-current imaging." Thesis, University of Surrey, 1985. http://epubs.surrey.ac.uk/707/.
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Fox, William Randolph II. "Experimental study of current-driven turbulence during magnetic reconnection." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/52784.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2009.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student submitted PDF version of thesis.
Includes bibliographical references (p. 177-185).
Magnetic reconnection is an important process in magnetized plasmas ranging from the laboratory to astrophysical scales. It enables the release of magnetic energy believed to power solar flares and magnetospheric substorms. Reconnection also controls the evolution of the topology of the magnetic field, enabling deleterious instabilities, such as the sawtooth instability in fusion experiments, to transport plasma across the experiment's minor radius. Notably, simple estimates of the finite reconnection rate due to classical resistivity fail to explain the fast and explosive nature of reconnection observed in these systems. A major goal of reconnection research is to determine which mechanisms enable "fast" reconnection to occur. This thesis studied the fluctuations arising in the plasma during magnetic reconnection experiments on the Versatile Toroidal Facility (VTF), with a primary goal of testing whether "anomalous resistivity" due to micro-instabilities can speed the reconnection process. Fluctuations were studied using impedance-matched, high-bandwidth Langmuir probes. Strong, broadband fluctuations, with frequencies extending from near the lower-hybrid frequency [fLH = (fcefci)1=2] to the electron cyclotron frequency fce were found to arise during the reconnection events. Based on frequency and wavelength measurements, lower-hybrid waves and Trivelpiece-Gould waves were identied. The lower-hybrid waves appear to be driven by strong perpendicular drifts or gradients which arise due to the reconnection events; an appealing possibility is strong temperature gradients.
(cont.) The Trivelpiece-Gould modes were found to result from kinetic, bump-on-tail instability of a runaway electron population energized by the reconnection events. Nonlinear, spiky turbulence was also observed, and attributed to the creation of "electron phase-space holes," a class of nonlinear solitary wave known to evolve from a strong beam-on-tail instability. Overall, these instabilities were found to be a consequence of reconnection, specifically the strong energization of electrons, leading to steep gradients in both coordinate- and velocity-space. However, it was not established that these modes had a strong feedback on the reconnection process: fluctuation power varied strongly between discharges and was observed to systematically trail the reconnection events. Finally, crude estimates (using quasi-linear theory) of the anomalous resistivity due to these modes did not appear large enough to substantially impact the reconnection process.
by William Randolph Fox, II.
Ph.D.
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Bungey, Timothy N. "Topological configurations of coronal magnetic fields and current sheets." Thesis, University of St Andrews, 1996. http://hdl.handle.net/10023/14021.
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The question of topology in the coronal magnetic field is addressed in this thesis. Magnetic reconnection, which plays a major role in many of the fascinating phenomena seen in the solar atmosphere, is likely to occur at the boundaries between different topological regions of the magnetic field. By modelling the coronal field using discrete sources of flux, to represent the concentrations seen at the photospheric surface, we study the varying topological structures present in the field. We generate a criterion for determining the presence of null points above the photospheric surface and establish that any separatrix surfaces present in the field are due to the presence of either null points, or regions where the field tangentially grazes the surface. We follow the evolution of these separatrix surfaces and, in particular, determine the existence of a well-defined separator field line in the absence of coronal null points. Finally, we look locally at the configuration of the magnetic field in the region surrounding a straight current sheet. We derive an analytical expression to describe the topology of both potential and constant-current force-free fields in the neighbourhood of a sheet, and in so doing generalise the previously known expressions.
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Yang, Lei. "Current induced domain wall motion : analysis and simulation /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?MATH%202008%20YANG.
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Gay, Sebastien Emmanuel. "Contactless magnetic brake for automotive applications." [College Station, Tex. : Texas A&M University, 2005. http://hdl.handle.net/1969.1/ETD-TAMU-1005.
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Bocquet, Francois-Xavier. "Investigations of current build up in topologically simple magnetic fields." Thesis, University of St Andrews, 2005. http://hdl.handle.net/10023/11291.
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The solar corona is a highly conductive plasma which is dominated by the coronal magnetic field. Observations show that important solar phenomena like flares or the heating of the corona are driven by magnetic energy, probably through the process of magnetic reconnection. The release of magnetic energy by reconnection requires that non-ideal processes take place in contradiction to the high conductivity of the corona. One possibility to overcome this problem is to generate strong electrical currents in strongly localised regions. In this thesis we investigate how such localised currents can be formed by slow ideal evolution of topologically simple magnetic fields. To this purpose numerical simulations are carried out using an Eulerian and a Lagrangian MHD relaxation code. We first use a simple example (twisting of a uniform field) to investigate the advantages and disadvantages of both codes and to discover possible limitations for their application. We show that for the problems addressed in this thesis the Lagrangian code is more suited because it can resolve the localised current densities much better than the Eulerian code. We then focus in particular on magnetic fields containing a so-called Hyperbolic Flux Tube (HPT). A recently proposed analytical theory predicts that HFT's are sites where under certain conditions strong current build-up can be expected. We use our code to carry out a systematic parametric study of the dependence of current growth for a typical HFT configuration. We have also developed a completely new version of the analytical theory which is directly based on the set-up of our numerical simulations. We find that the simulations agree with the analytical prediction in a quantitative way but that the analytical theory underestimates the current growth quite substantially, probably by not taking into account the non-linear character of the full problem.
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at, Andreas Cap@esi ac. "Semiclassics of the Quantum Current in Very Strong Magnetic Fields." ESI preprints, 2001. ftp://ftp.esi.ac.at/pub/Preprints/esi1069.ps.
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Altunel, Haluk. "Optimum Current Injection Strategy For Magnetic Resonance Electrical Impedance Tomography." Phd thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609340/index.pdf.
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In this thesis, optimum current injection strategy for Magnetic Resonance Electrical
Impedance Tomography (MREIT) is studied. Distinguishability measure based on
magnetic flux density is defined for MREIT. Limit of distinguishability is
analytically derived for an infinitely long cylinder with concentric and eccentric
inhomogeneities. When distinguishability limits of MREIT and Electrical
Impedance Tomography (EIT) are compared, it is found that MREIT is capable of
detecting smaller perturbations than EIT. When conductivities of inhomogeneity
and background object are equal to 0.8S and 1S respectively, MREIT provides
improvement of %74 in detection capacity. Optimum current injection pattern is
found based on the distinguishability definition. For 2-D cylindrical body with
concentric and eccentric inhomogeneities, opposite drive provides best result. As
for the 3-D case, a sphere with azimuthal symmetry is considered.
Distinguishability limit expression is obtained and optimum current injection
pattern is again opposite drive. Based these results, optimum current injection
principles are provided and Regional Image Reconstruction (RIR) using optimum
currents is proposed. It states that conductivity distribution should be reconstructed
for a region rather than for the whole body. Applying current injection principles
and RIR provides reasonable improvement in image quality when there is noise in
the measurement data. For the square geometry, when SNR is 13dB, RIR provides
decrement of nearly %50 in conductivity error rate of small inhomogeneity. Pulse
sequence optimization is done for Gradient Echo (GE) and it is compared with Spin
Echo (SE) in terms of their capabilities for MREIT.
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Stechow, Adrian von [Verfasser]. "Current sheet dynamics during driven magnetic reconnection / Adrian von Stechow." Greifswald : Universitätsbibliothek Greifswald, 2015. http://d-nb.info/1073164306/34.
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Bromberg, David M. "Current-Driven Magnetic Devices for Non-Volatile Logic and Memory." Research Showcase @ CMU, 2014. http://repository.cmu.edu/dissertations/418.
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Magnetic logic has entered the spotlight as an intriguing candidate for future electronic systems. Recently we proposed a magnetic logic technology (“mLogic”) based on a current driven four terminal device (“mCell”) with isolated read- and write- paths. The first step with this nascent technology is to understand the device limitations and performance in response to input stimuli and material properties. In this thesis we explore the design, micromagnetic modeling, and experimental verification of mCell devices. The concept of an mCell is best described as a “black box” device with four terminals. Two terminals constitute a write-path, wherein the direction of input current flows to program the digital state of the device. The other two terminals constitute a read-path that is electrically isolated from the write-path. The state of the device is read out as a high or low resistance through the read-path terminals. Because multiple nanomagnetic phenomena (including spin transfer torque and the spin Hall effect) can be used to program a magnetization (logic) state based on a current direction, we introduce several mCell designs that all satisfy the conceptual 4- terminal mCell model. For each design we describe the operating principles and key features, followed by a presentation of modeling results that indicate performance trends. Of particular focus is the influence of material properties and device geometry on the current density required to instigate state switching. It is found that with appropriate design choices in scaled devices, sub-10 μA switching currents are achievable. Furthermore, we explore other mCell designs that can accommodate switching times below 1 ns. As part of this device exploration work, we experimentally demonstrate successful domain wall motion, tunnel magnetoresistance, and coupling through a magnetic oxide to validate writepath, read-path, and interlayer components. These components are then integrated into a prototype device. We show this prototype can be reliably switched into one of two (binary) states by pulsing current through the write-path, thereby demonstrating the fundamental mCell concept. We conclude this thesis by proposing future research directions in device design and fabrication to improve this device to enable logic circuits and all-magnetic MRAM bitcells.
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Gokce, Aisha. "Low frequency current and resistance fluctuations in magnetic tunnel junctions." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 203 p, 2009. http://proquest.umi.com/pqdweb?did=1896928791&sid=9&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Andriyas, Tushar. "Particle Dynamics and Resistivity Characteristics in Bifurcated Current Sheets." DigitalCommons@USU, 2013. http://digitalcommons.usu.edu/etd/1513.
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Charged particle chaos and its collective effects in different magnetic geometries are investigated in a sequence of various numerical experiments. The fields generated by the particles as a result of interaction with the background electric and magnetic fields is not accounted for in the simulation. An X-line is first used to describe the geometry of the magnetotail prior to magnetic reconnection and a study of the behavior of charged particles is done from a microscopic viewpoint. Another important geometry in the magnetotail prior to substorm onset is Bifurcated Current Sheet. The same analysis is done for this configuration. The existence of at least one positive Lyapunov exponent shows that the motion of the particles is chaotic. By using statistical mechanics, the macroscopic properties of this chaotic motion are studied. Due to particles being charged, an electric field (perpendicular to the magnetic field in weak magnetic field region) accelerates the particles on average. Finite average velocity in the direction of electric field gives rise to an effective resistivity even in a collisionless regime such as solar corona and the magnetotail. Starting from initial velocities that are chosen randomly from a uniform distribution, the evolution of these distributions tends to a Maxwellian by the end of the simulation that is somewhat analogous to collisions in a Lorentz gas model. The effective resistivity due to such collisions is estimated. Ohmic heating is found to occur as a result of such an effective resistivity. Such collisions due to collective particle effects are essentially a different mechanism from classical collision notion. These experiments are done for two types of ions found in the plasma sheet prior to substorm onset, viz., protons and oxygen ions. Observational evidence of oxygen ions in the central plasma sheet, which flow out along open field lines from the ionosphere, were also simulated in the same manner. Oxygen ions have been found to influence the bifurcation of the current sheet and are also important in reconnection and other nonohmic instabilities, such as Kelvin Helmholtz instability, due to their mass. It is found that acceleration in X-line scales with the mass of ion species and the resistivity remains constant for different electric field strengths. In a Bifurcated Current Sheet, the acceleration scales with the square of mass of ion species and the resistivity scales with the electric field. Also, the overall resistivity values found in a Bifurcated Current Sheet are an order of magnitude lower than that found in an X-line.
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Gärskog, Gustav. "NUMERICAL CALCULATION METHOD FOR MAGNETIC FIELDS IN THE VICINITY OF CURRENT-CARRYING CONDUCTORS." Thesis, Uppsala universitet, Elektricitetslära, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-353338.
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This thesis aims to develop a calculation method to determine themagnetic field magnitudes in the vicinity of power lines, i.e. bothburied cables and overhead lines. This is done through the numericaluse of Biot Savart's law where the conductors are approximated by aseries of straight segment elements that each contribute to the overallfield strength at the field point. The method is compared to two realcases and to the exact integral solution. Also, a review of some of theresearch material regarding electromagnetic fields from power lines andclaims of adverse health effects due to these fields is conducted.Results show that the numerical error is dependent on the segmentationdegree of the conductors and the mathematical model is inaccurate closeto the conductor. The calculations show slightly higher fieldmagnitudes than the previous survey done by WSP (Williams SalePartnership) far away from the source and slightly lower at the centerconductor. This may be due to the excluded induction in the shieldwires and differences in actual conductor coordinates.
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Yazgan, Selahattin Baris. "Modeling of Eddy Current Separation." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/92000.
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Eddy current separation aims to recover non-ferrous metals from non-metals utilizing electromagnetic interactions. In order to describe the separation process, a representative model is needed that can accurately calculate the induced forces. Such a model can be used to optimize the efficiency of current equipment as well as designing ones that can offer new capabilities. Models proposed so far for the separation process, using traditional approaches to calculate forces, had limited success due to complex nature of electromagnetic interactions.
In this dissertation, a novel method for calculating the magnetic force acting on non-ferrous metal particles was developed. By this method, force calculations can be carried out accurately using intrinsic parameters of particles such as size and shape, as well as its orientation within the field. The method also takes into account the operating parameters of the equipment such as the rotational speed of the magnetic element and the speed of the belt. In order to verify this method and collect empirical data, a novel data acquisition and interpretation approach was developed.
A computer simulator was also developed that can calculate trajectories of particles based on operating parameters of the eddy current separator and characteristics of the material being processed. The accuracy of the simulator was verified using empirical data obtained by the novel data acquisition method.
This contribution provides a viable option for reducing the cost of analyzing; optimizing and designing eddy current separators.PHD
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Eriksson, Elin. "3D Magnetic Nulls and Regions of Strong Current in the Earth's Magnetosphere." Licentiate thesis, Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-292742.
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Plasma, a gas of charged particles exhibiting collective behaviour, can be found everywhere in our vast Universe. The characteristics of plasma in very distant parts of the Universe can be similar to characteristics in our solar system and near-Earth space. We can therefore gain an understanding of what happens in astrophysical plasmas by studying processes occurring in near Earth space, an environment much easier to reach. Large volumes in space are filled with plasma and when different plasmas interact distinct boundaries are often created. Many important physical processes, for example particle acceleration, occur at these boundaries. Thus, it is very important to study and understand such boundaries. In Paper I we study magnetic nulls, regions of vanishing magnetic fields, that form inside boundaries separating plasmas with different magnetic field orientations. For the first time, a statistical study of magnetic nulls in the Earth’s nightside magnetosphere has been done by using simultaneous measurements from all four Cluster spacecraft. We find that magnetic nulls occur both in the magnetopause and the magnetotail. In addition, we introduce a method to determine the reliability of the type identification of the observed nulls. In the manuscript of Paper II we study a different boundary, the shocked solar wind plasma in the magnetosheath, using the new Magnetospheric Multiscale mission. We show that a region of strong current in the form of a current sheet is forming inside the turbulent magnetosheath behind a quasi-parallel shock. The strong current sheet can be related to the jets with extreme dynamic pressure, several times that of the undisturbed solar wind dynamic pressure. The current sheet is also associated with electron acceleration parallel to the background magnetic field. In addition, the current sheet satisfies the Walén relation suggesting that plasmas on both sides of the current region are magnetically connected. We speculate on the formation mechanisms of the current sheet and the physical processes inside and around the current sheet.
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Harrison, Michael George. "Equilibrium and dynamics of collisionless current sheets." Thesis, St Andrews, 2009. http://hdl.handle.net/10023/705.
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Zhang, Xiaokai. "Novel magnetic composites for high frequency applications /." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 190 p, 2009. http://proquest.umi.com/pqdweb?did=1654494811&sid=2&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Simm, Anthony. "Quantitative interpretation of magnetic field measurements in eddy current defect detection." Thesis, University of Newcastle Upon Tyne, 2013. http://hdl.handle.net/10443/1809.
Full textAbstract:
For many years, the theoretical and experimental study of eddy current non-destructive evaluation (NDE) has been conducted separately, as most models were not suited to practical industrial applications. The aim of this work is to bridge this gap by investigating the relationship between magnetic fields and defects using both modelling and experimental study and to link these results to quantitative NDE. In this work, 3D FEM numerical simulations are used to predict the response of an eddy current probe being scanned over the area of a defect and understand the underlying change in magnetic field due to the presence of the defect. Experimental investigations are performed to study the feasibility of the proposed magnetic field measurement techniques for defect detection. This experimental work investigates the inspection of both surface and subsurface defects, the use of rectangular (directional) probes and the measurement of complex magnetic field values, as the response in these cases has been found to have a greater correlation with the shape of the defect being studied. As well as the detection of defects, both frequency spectrum and transient information from pulsed eddy current responses are used to reconstruct the profile (depth and width) of a slot shaped defect. The work concludes that the use of magnetic field measurements provides useful information for defect detection and quantification. This will have applications in both industrial and research areas, including visualisation of defects from magnetic field measurements, which can be applied to the monitoring of safety critical components.
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Rizal, C., B. R. Karki, and Yu Ueda. "Magnetic properties of Fe/Cu multilayers prepared using pulsed-current electrodeposition." Thesis, Видавництво СумДУ, 2011. http://essuir.sumdu.edu.ua/handle/123456789/20966.
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Ellis, J. J. "The control of resistive instabilities in pinches." Thesis, University of Oxford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.353080.
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Guldemir, Hanifi. "Prediction of induction motor line current spectra from design data." Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287180.
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Lepadatu, Serban. "Domain wall scattering and current induced magnetic switching in patterned ferromagnetic nanowires." Thesis, University of York, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434015.
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Curtis, Ryan. "Theory of current-driven domain wall motion in artificial magnetic domain structures." Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.665451.
Full textAbstract:
This thesis concerns the combination of two overlapping fields in physics: condensed matter and electromagnetism. Specifically the problem posed of simulating the movement of magnetic domains by applied magnetic, and electric, fields. In this investigation electronic structure methods are used in an attempt to parametrise longer length-scale micromagnetic simulations. Previous works in the field have relied upon suitable experiments having been conducted, whereas this work can stand alone - albeit with its own propagation of systematic errors. Modelling is undertaken to predict the applicability of cobalt platinum multilayers as a new type of computer memory. Although results are promising, features not in the remit of this thesis, such as practicality, are noted to be major obstacles that would need to be overcome. Ab initio methods are used with varying success to predict the saturation magnetisation, Gilbert damping parameter, and anisotropy parameter of cobalt platinum systems.
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Ferri, Matthew A. (Matthew Anthony). "Current distribution and stability criteria for superconducting cables in transient magnetic fields." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10406.
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Bowness, Ruth. "Current sheets in the solar corona : formation, fragmentation and heating." Thesis, University of St Andrews, 2011. http://hdl.handle.net/10023/2081.
Full textAbstract:
In this thesis we investigate current sheets in the solar corona. The well known 1D model for the tearing mode instability is presented, before progressing to 2D where we introduce a non-uniform resistivity. The effect this has on growth rates is investigated and we find that the inclusion of the non-uniform term in η cause a decrease in the growth rate of the dominant mode. Analytical approximations and numerical simulations are then used to model current sheet formation by considering two distinct experiments. First, a magnetic field is sheared in two directions, perpendicular to each other. A twisted current layer is formed and we find that as we increase grid resolution, the maximum current increases, the width of the current layer decreases and the total current in the layer is approximately constant. This, together with the residual Lorentz force calculated, suggests that a current sheet is trying to form. The current layer then starts to fragment. By considering the parallel electric field and calculating the perpendicular vorticity, we find evidence of reconnection. The resulting temperatures easily reach the required coronal values. The second set of simulations carried out model an initially straight magnetic field which is stressed by elliptical boundary motions. A highly twisted current layer is formed and analysis of the energetics, current structures, magnetic field and the resulting temperatures is carried out. Results are similar in nature to that of the shearing experiment.
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Xiao, Jiang. "Spin-transfer Torque in Magnetic Nanostructures." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/11513.
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This thesis consists of three distinct components: (1) a test of Slocnzewski's theory of spin-transfer torque using the Boltzmann equation, (2) a comparison of macrospin models of spin-transfer dynamics in spin valves with experimental data, and (3) a study of spin-transfer torque in continuously variable
magnetization.
Slonczewski developed a simple circuit theory for spin-transfer torque in spin valves with thin spacer layer. We developed a numerical method to calculate the spin-transfer torque in a spin valve using Boltzmann equation. In almost all realistic cases, the circuit theory predictions agree well with the Boltzmann equation results.
To gain a better understanding of experimental results for spin valve systems, current-induced magnetization dynamics for a spin valve are studied using a single-domain approximation and a generalized Landau-Lifshitz-Gilbert equation. Many features of the experiment were reproduced by the simulations. However, there are two significant discrepancies: the current dependence of the magnetization precession frequency, and the presence and/or absence of a microwave quiet magnetic phase with a distinct magnetoresistance signature.
Spin-transfer effects in systems with continuously varying magnetization also have attracted much attention. One key question is under what condition is the spin current adiabatic, i.e., aligned to the local magnetization. Both quantum and semi-classical calculations of the spin current and spin-transfer torque are done in a free-electron Stoner model. The calculation shows that, in the adiabatic limit, the spin current aligns to the local magnetization while the spin density does not. The reason is found in an effective field produced by the gradient of the magnetization in the wall. Non-adiabatic effects arise for short domain walls, but their magnitude decreases exponentially as the wall width increases.
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Laestadius, Andre. "Foundation of Density Functionals in the Presence of Magnetic Field." Doctoral thesis, KTH, Matematik (Avd.), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-145546.
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This thesis contains four articles related to mathematical aspects of Density Functional Theory. In Paper A, the theoretical justification of density methods formulated with current densities is addressed. It is shown that the set of ground-states is determined by the ensemble-representable particle and paramagnetic current density. Furthermore, it is demonstrated that the Schrödinger equation with a magnetic field is not uniquely determined by its ground-state solution. Thus, a wavefunction may be the ground-state of two different Hamiltonians, where the Hamiltonians differ by more than a gauge transformation. This implies that the particle and paramagnetic current density do not determine the potentials of the system and, consequently, no Hohenberg-Kohn theorem exists for Current Density Functional Theory formulated with the paramagnetic current density. On the other hand, by instead using the particle density as data, we show that the scalar potential in the system's Hamiltonian is determined for a fixed magnetic field. This means that the Hohenberg-Kohn theorem continues to hold in the presence of a magnetic field, if the magnetic field has been fixed. Paper B deals with N-representable density functionals that also depend on the paramagnetic current density. Here the Levy-Lieb density functional is generalized to include the paramagnetic current density. It is shown that a wavefunction exists that minimizes the "free" Hamiltonian subject to the constraints that the particle and paramagnetic current density are held fixed. Furthermore, a convex and universal current density functional is introduced and shown to equal the convex envelope of the generalized Levy-Lieb density functional. Since this functional is convex, the problem of finding the particle and paramagnetic current density that minimize the energy is related to a set of Euler-Lagrange equations. In Paper C, an N-representable Kohn-Sham approach is developed that also include the paramagnetic current density. It is demonstrated that a wavefunction exists that minimizes the kinetic energy subject to the constraint that only determinant wavefunctions are considered, as well as that the particle and paramagnetic current density are held fixed. Using this result, it is then shown that the ground-state energy can be obtained by minimizing an energy functional over all determinant wavefunctions that have finite kinetic energy. Moreover, the minimum is achieved and this determinant wavefunction gives the ground-state particle and paramagnetic current density. Lastly, Paper D addresses the issue of a Hohenberg-Kohn variational principle for Current Density Functional Theory formulated with the total current density. Under the assumption that a Hohenberg-Kohn theorem exists formulated with the total current density, it is shown that the map from particle and total current density to the vector potential enters explicitly in the energy functional to be minimized. Thus, no variational principle as that of Hohenberg and Kohn exists for density methods formulated with the total current density.QC 20140523
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Woźniak, Mariusz. "High engineering critical current density MgB2 wires and joints for MRI applications." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610780.
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Chung, Yoon Do. "Basic Studies on Persistent Current Compensator for Superconducting Magnet by Use of Linear Type Magnetic Flux Pump." 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/49144.
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学位授与大学：京都大学 ; 取得学位: 博士(工学) ; 学位授与年月日: 2007-09-25 ; 学位の種類: 新制・課程博士 ; 学位記番号: 工博第2864号 ; 請求記号: 新制/工/1421 ; 整理番号: 25549Kyoto University (京都大学)
0048
新制・課程博士
博士(工学)
甲第13393号
工博第2864号
新制||工||1421(附属図書館)
25549
UT51-2007-Q794
京都大学大学院工学研究科電気工学専攻
(主査)教授 引原 隆士, 教授 小林 哲生, 准教授 中村 武恒
学位規則第4条第1項該当
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Boyacioglu, Rasim. "Performance Evaluation Of Current Density Based Magnetic Resonance Electrical Impedance Tomography Reconstruction Algorithms." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12611016/index.pdf.
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Magnetic Resonance Electrical Impedance Tomography (MREIT) reconstructs
conductivity distribution with internal current density (MRCDI) and boundary
voltage measurements. There are many algorithms proposed for the solution of
MREIT inverse problem which can be divided into two groups: Current density (J)
and magnetic flux density (B) based reconstruction algorithms. In this thesis, J-based
MREIT reconstruction algorithms are implemented and optimized with
modifications. These algorithms are simulated with five conductivity models which
have different geometries and conductivity values. Results of simulation are
discussed and reconstruction algorithms are compared according to their
performances. Equipotential-Projection algorithm has lower error percentages than
other algorithms for noise-free case whereas Hybrid algorithm has the best
performance for noisy cases. Although J-substitution and Hybrid algorithms have
relatively long reconstruction times, they produced the best images perceptually.
v
Integration along Cartesian Grid Lines and Integration along Equipotential Lines
algorithms diverge as noise level increases. Equipotential-Projection algorithm has
erroneous lines starting from corners of FOV especially for noisy cases whereas
Solution as a Linear Equation System has a typical grid artifact. When performance
with data of experiment 1 is considered, only Solution as a Linear Equation System
algorithm partially reconstructed all elements which show that it is robust to noise.
Equipotential-Projection algorithm reconstructed resistive element partially and other
algorithms failed in reconstruction of conductivity distribution. Experimental results
obtained with a higher conductivity contrast show that Solution as a Linear Equation
System, J-Substitution and Hybrid algorithms reconstructed both phantom elements
and Hybrid algorithm is superior to other algorithms in percentage error comparison.
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Kikuchi, Y., H. Takahashi, Y. Uesugi, and S. Takamura. "Suppression of Externally Induced Magnetic Island by Plasma Current Oscillation in HYBTOK-II." IEEE, 2003. http://hdl.handle.net/2237/7109.
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Wang, Jinou [Verfasser]. "The Current Slope Based Position Estimation for Self-Sensing Magnetic Bearings / Jinou Wang." Aachen : Shaker, 2016. http://d-nb.info/1101184736/34.
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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.
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The conversion of mechanical energy to electrical energy is done mainly with synchronous generators. They are used in hydropower generators and nuclear plants that presently account for about 80% of the electric energy production in Sweden. Because of the dominating role of the synchronous generators, it is important to minimize the power losses for efficient use of natural resources and for the economies of the electric power companies and their customers. For a synchronous machine, power loss means undesired heat production. In electric machines, there are power losses due to windage, friction in bearings, resistance in windings, remagnetization of ferromagnetic materials, and induced voltages in windings, shields and parts that are conductive but ideally should be non-conductive. The subject of this thesis is prediction of end region magnetic leakage fields in synchronous generators and the eddy current power losses they cause. The leakage fields also increase the hysteresis losses in the end regions. Magnetic flux that takes paths such that eddy current power losses increase in end regions of synchronous generators is considered to be leakage flux. Although only a small fraction of the total magnetic flux is end region leakage flux, it can cause hot spots, discoloration and reduce the service life of the insulation on the core laminations. If unattended, damaged insulation could lead to electric contact and eddy currents induced by the main flux between the outermost laminations. That gives further heating and deterioration of the insulation of laminations deeper into the core. In a severe case, the core can melt locally, cause a cavity, buckling and a short circuit of the main conductors. The whole stator may have to be replaced. However, the end region leakage flux primarily causes heating close to the main stator conductors which makes the damage possible to discover by visual inspection before it has become irrepairable.
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Zhang, Yanjing. "Electric and magnetic contributions and defect interactions in remote field eddy current techniques." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq22507.pdf.
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Kato, K., T. Noda, H. Shimizu, T. Matsumura, and N. Murayama. "Increase in transient resistance of Bi2223 superconducting bulk by applying external magnetic field." IEEE, 2001. http://hdl.handle.net/2237/6784.
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Abdulkariem, Heibetullah. "Measuring magnetically induced eddy current densities in biological structures at low frequencies : circuit design and applications." Thesis, University of Aberdeen, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385153.
Full textAbstract:
Electrical eddy currents can be induced inside biological tissue by time-varying magnetic fields according to Faraday's law of induction. These eddy currents are responsible for biological effects such as visual sensations in eyes called magnetophosphenes and they accelerate the healing process of fractured bones in magnetotherapy operation. Induced eddy currents also cause neuromuscular stimulation of cardiac muscle, shown as a disturbance in the electrocardiogram and respiratory disturbance shown as a brief period of apnoea (stopped breathing) and muscle contraction in the forearm and finger. Brain cortex also can be stimulated by pulsed magnetic fields. A transient decrease in blood flow in the human skin is seen as a result of exposing the skin to pulsed magnetic fields. To study the effects of time-varying magnetic field, a method is needed to assess and measure induced current densities. Many attempts have been made to find such a method, both theoretically and practically. A theoretical model with homogenous and isotropic concentric loops of tissue was suggested but biological tissues are neither homogenous nor isotropic. A Hall effect method using a slab of semiconductor was suggested for measurement of current densities inside tissues, but this method ignored disturbances in the current pathways inside the tissue as a result of differences in impedances between the semiconductor and the tissue. A cube substitution method using platinized conductive faces implanted in the tissue does not consider problems of alignment of the probes with the direction of isopotential lines or electrode-electrolyte impedance. Also, such electrodes measure only dc current. In a method using a three dimensional electrode to provide three-dimensional information, the author did not give evidence that these electrodes have a zero field distortion, and also did not give information about measurements made using his electrodes. None of the above methods provide a solid approach to the problems of measuring induced current densities. This thesis attempts to present a method of measuring induced current density. The method is capable of measuring both the magnitude and direction of induced current densities. It uses five point electrodes, four of them applied inside the tissue while the fifth one is just in electrical contact with the tissue. The method consists of a probe configuration system, an open-loop operational amplifier and a balanced semi-floating current driver. Leakage current, which goes to the ground and causes error, can be adjusted to be very low (about 0.01% of the total output current). A pair of Helmoltz coils was employed to provide a system for producing time-varying magnetic field. The core of the coil pair was shielded and grounded by a cut metal shield, to avoid any interference from time-varying electric field. The shield was also used as a metal incubator to keep biological samples at body temperature. The heat to the shield was supplied by a unit consisting of four power transistors, and a circuit of sensing, and controlling components. The method used in this study was tested by making measurements of eddy current densities induced in physiological saline solution as a model of a biological conducting fluid. The measurements were represented by arrows, each representing a single measurement, with the length of the arrow representing the magnitude of current density and the direction representing the direction of the induced current. Because electrically induced eddy currents are dependent on electric charge density available inside tissue, and therefore dependent on tissue electrical conductivity, this thesis presents a direct and simple method for measuring complex tissue electrical conductivity. The method uses the same five-electrode system and shares the same point electrode configurations and balanced semi-floating current driver as used for eddy current measurements. The method measures both real and imaginary components of tissue complex conductivity. Both systems are gathered into one box and their functions are separated by four toggle switches. Measurements of electrical induced current densities and complex electrical conductivities for body fluids and tissues have been carried out on saline solutions with different ionic concentrations, expired human whole blood, expired human plasma, human cerebrospinal fluid (CSF) and human urine. Solid tissue such as bovine cardiac muscle and liver were also examined. Current-to-field ratios were obtained for experiments in both fluid and tissues.
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Wang, Shen. "Modeling and Design of Planar Integrated Magnetic Components." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/34400.
Full textAbstract:
Recently planar magnetic technologies have been widely used in power electronics, due to good cooling and ease of fabrication. High frequency operation of magnetic components is a key to achieve high power density and miniaturization. However, at high frequencies, skin and proximity effect losses in the planar windings become significant, and parasitics cannot be ignored. This piece of work deals with the modeling and design of planar integrated magnetic component for power electronics applications.
First, one-dimensional eddy current analysis in some simple winding strategies is discussed. Two factors are defined in order to quantify the skin and proximity effect contributions as a function of frequency. For complicated structures, 2D and 3D finite element analysis (FEA) is adopted and the accuracy of the simulation results is evaluated against exact analytical solutions.
Then, a planar litz structure is presented. Some definitions and guidelines are established, which form the basis to design a planar litz conductor. It can be constructed by dividing the wide planar conductor into multiple lengthwise strands and weaving these strands in much the same manner as one would use to construct a conventional round litz wire. Each strand is subjected to the magnetic field everywhere in the winding window, thereby equalizing the flux linkage. 3D FEA is utilized to investigate the impact of the parameters on the litz performance. The experimental results verify that the planar litz structure can reduce the AC resistance of the planar windings in a specific frequency range.
After that, some important issues related to the planar boost inductor design are described, including core selection, winding configuration, losses estimation, and thermal modeling. Two complete design examples targeting at volume optimization and winding parasitic capacitance minimization are provided, respectively.
This work demonstrates that planar litz conductors are very promising for high frequency planar magnetic components. The optimization of a planar inductor involves a tradeoff between volumetric efficiency and low value of winding capacitance. Throughout, 2D and 3D FEA was indispensable for thermal & electromagnetic modeling.Master of Science
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Wong, Lam Chuen. "The spin polarization of current passing through a double level quantum dot under magnetic field /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?PHYS%202005%20WONG.
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Bunting, Robert J. "Development and use of a current wedge modelling method for analysis of multiple onset substorms." Thesis, University of York, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338555.
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Nalladega, 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.
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