Dissertations / Theses: 'Electromagnetic theory. Electromagnetic fields'

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Bradley, G. "Risk perception and communication within a personal construct theory framework." Thesis, Queen's University Belfast, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273180.

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Veilleux, Douglas L. "Melting in a low gravity environment with applied electromagnetic fields /." View online ; access limited to URI, 2005. http://0-wwwlib.umi.com.helin.uri.edu/dissertations/dlnow/3186925.

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Henkel, Carsten. "Coherence theory of atomic de Broglie waves and electromagnetic near fields." Thesis, [S.l. : s.n.], 2004. http://pub.ub.uni-potsdam.de/2004/0027/henkel.pdf.

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Mesirca, Pietro <1972&gt. "Electrical activity in neurons exposed to low level electromagnetic fields: theory and experiments." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/505/.

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Matloob, Mohammad Reza. "Theory of electromagnetic field quantization in material media." Thesis, University of Essex, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282572.

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

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7

Sufian, Raza Sabbir. "DISCONNECTED-SEA QUARKS CONTRIBUTION TO NUCLEON ELECTROMAGNETIC FORM FACTORS." UKnowledge, 2017. http://uknowledge.uky.edu/physastron_etds/49.

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We present comprehensive analysis of the light and strange disconnected-sea quarks contribution to the nucleon electric and magnetic form factors. The lattice QCD estimates of strange quark magnetic moment GsM (0) = −0.064(14)(09) μN and the mean squared charge radius ⟨r2s⟩E = −0.0043(16)(14) fm2 are more precise than any existing experimental measurements and other lattice calculations. The lattice QCD calculation includes ensembles across several lattice volumes and lattice spacings with one of the ensembles at the physical pion mass. We have performed a simultaneous chiral, infinite volume, and continuum extrapolation in a global fit to calculate results in the continuum limit. We find that the combined light-sea and strange quarks contribution to the nucleon magnetic moment is−0.022(11)(09) μN and to the nucleon mean square charge radius is −0.019(05)(05) fm2. The most important outcome of this lattice QCD calculation is that while the combined light-sea and strange quarks contribution to the nucleon magnetic moment is small at about 1%, a negative 2.5(9)% contribution to the proton charge radius and a relatively larger positive 16.3(6.1)% contribution to the neutron charge radius come from the sea quarks in the nucleon. For the first time, by performing global fits, we also give predictions of the light-sea and strange quarks contributions to the nucleon electric and magnetic form factors at the physical point and in the continuum and infinite volume limits in the momentum transfer range of 0 ≤ Q2 ≤ 0.5 GeV2.

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Wanis, Sameh Sadarous. "Tailored Force Fields for Flexible Fabrication." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/10540.

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The concept of tailored force fields is seen as an enabler for the construction of large scale space structures. Manufacturing would take place in space using in-situ resources thereby eliminating the size and weight restriction commonly placed on space vehicles and structures. This thesis serves as the first investigation of opening the way to a generalized fabrication technology by means of force fields. Such a technology would be non-contact, flexible, and automated. The idea is based on the principle that waves carry momentum and energy with no mass transport. Scattering and gradient forces are generated from various types of wave motion. Starting from experiments on shaping walls using acoustic force fields, this thesis extends the technology to electromagnetic fields. The interaction physics of electromagnetic waves with dielectric material is studied. Electromagnetic forces on neutral dielectric material are shown to be analogous to acoustic forces on sound-scattering material. By analogy to the acoustic experiments, force fields obtained by optical tweezers are extended to longer wavelength electromagnetic waves while remaining in the Rayleigh scattering regime. Curing of the surface formed takes place by use of a higher frequency beam that scans the surface and melts a subsurface layer enabling a sintering effect to take place between the particles. The resulting capability is explored at its extremes in the context of building massive structures in Space. A unification of these areas is sought through a generalization of the various theories provided in the literature applicable for each field.

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9

Hellsborn, Hannes. "A note on electromagnetic field theory and 1D modeling of synthetic CSAMT data." Thesis, Uppsala universitet, Geofysik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-183813.

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Controlled source audio magnetotellurics, or CSAMT, is one of the principal methods for electromagnetic measurements. A 1D model is a simple representation but a quite easy way to find the main features of the Earth's subsurface. The 1D inversion of CSAMT data that has been used in this report was presented by H.M. Maurer and X. Garcia (1995). The inversion was calculated with a Levenberg-Marquardt algorithm giving an iterative least-squares solution and the field calculations were based on those of Weidelt (1986). A cylindrical coordinate system was used to calculate the field response for a horizontal electric dipole. The main goal of this thesis has been to investigate these calculations and by using this, implement the field calculations of a horizontal magnetic dipole. The calculations are done with a numerical representation of the Hankel transformation. Using this approach, the program calculates the field response of a 1D layered earth model with a maximum of 10 layers. To find the sensitivities used in the Levenberg-Marquardt algorithm, a perturbation method has been used. Though the program was written with a semi-analytic method, this was not fully functional. To improve the sensitivities, this method has been reconstructed. To evaluate the program response, a program to calculate synthetic data has been written and synthetic data sets of four models has been used. Here, the calculations are made by the same numerical tables as the inversion program to avoid unnecessary errors. An exception is though made for the homogenous half space, where a simpler formulation has been used. Investigation of the program response show how well the field calculations corre- spond to the professional X3D program based on calculations by Avdeev et al. (2002). For higher (> 100 Hz) frequencies the deviation is alarmingly high which makes the result close to useless. This is though not seen in the lower frequencies where the result is much better. The deviation is also connected to the complexity of the model, i.e. the number of layers and resistivity contrast. This frequency problem is likely to be caused by failure in the numerical approximation for high frequencies. Due to the high frequency problem, a maximum of 100 Hz has been used when looking at the errors in the output models. When lowering the frequency range, there is some convergence for the simplest model, a homogenous half space. The more complex models do not converge for any frequency range and due to this, one conclusion is that the problem can be found in the inversion algorithm itself and not in the field calculations.

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10

Chege, Gerald Wachira. "The theory and application of variable grain parallel computation in electromagnetic field scattering." Thesis, University of York, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280384.

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Gulick, Sidney Luther. "Ion injection into radio frequency quadrupole field devices." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66038.

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Tardioli, Giampaolo. "Modeling of fine geometric details and singular field regions in TLM." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0001/NQ34286.pdf.

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Demetrescu, Cristian. "Elements of diffraction theory for urban radiowave propagation modelling." Thesis, University of Birmingham, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340005.

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14

Chakraborty, Sankar. "Scalar, electromagnetic and elastic waves in periodic and certain broken-periodicity media /." free to MU campus, to others for purchase, 1997. http://wwwlib.umi.com/cr/mo/fullcit?p9842515.

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15

Dommermuth, Marius Hermann [Verfasser], and Nils [Akademischer Betreuer] Schopohl. "Theory on the local electromagnetic field in crystalline dielectrics / Marius Hermann Dommermuth ; Betreuer: Nils Schopohl." Tübingen : Universitätsbibliothek Tübingen, 2019. http://d-nb.info/1194370454/34.

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Seutin, Rodric [Verfasser], Achim [Akademischer Betreuer] Schwenk, and Kai [Akademischer Betreuer] Hebeler. "Electromagnetic Properties of Light Nuclei with Chiral Effective Field Theory Currents / Rodric Seutin ; Achim Schwenk, Kai Hebeler." Darmstadt : Universitäts- und Landesbibliothek, 2021. http://d-nb.info/1228537402/34.

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17

Meloling, John H. "A caustic corrected uniform geometrical theory of diffraction for evaluating high-frequency electromagnetic fields near the cusp of the caustic caused by the curvature of an edge /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487853913101801.

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18

Sandlund, Erik. "Modelling the Magnetic Influence of a Jet Aircraft : A study on the magnetic interference of an aircraft configuration and its effect on a magnetometer." Thesis, Linköpings universitet, Teoretisk Fysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-157743.

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Aircraft have been used for the detection of submarines since World War II. The basic concept is to attach a sensor to the back of an aircraft. Since the aircraft is a moving metallic object, it is bound to generate a great deal of interference. Because of this, mathematical models and software have been developed to help filter out this interference and thus make the detection of the submarine easier. Normally, the engines of the aircraft are placed on the wings, quite far away from the sensor. However, for a maritime patrol system in development, the jet engines are placed at the rear of the airframe, generating the necessity to study whether or not they affect the performance of the sensor, which is the purpose of this thesis. Several models were created, tested and simulated for the airframe and jet engines. One of each of these were then combined to create a simulation model for the complete aircraft. A jet engine model that included rotating machinery -- a possible source of magnetic interference -- was also created, but could not be added to the model for the complete aircraft. The magnetic interference was mathematically compensated for, removing the static interference, but not the interference during manoeuvres. The jet engine part of the complete aircraft model did not seem to generate a significant amount of magnetic interference compared to the airframe. An electric dipole, representing a submarine, was then added to the simulation. The data from that simulation was put through the mathematical model and distortions of a few~nT were noticeable during straight courses. The jet engine model that included rotating machinery yielded different results compared to the jet engine model in the complete aircraft model. They seemed to contain signals of higher frequency, which were however not detected by a frequency domain study or present during straight courses. It was thus concluded that using this particular engine model the submarine could probably still be detected if the course of the aircraft was kept straight, though further research is needed with more advanced models for the engine, in particular with regards to the rotating machinery.

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Revalee, Jason S. "Accessibility and The Potential of Bio-Physiological Systems Measuring Human Magnetic Fields to Inform Technology Devices." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1559057599496862.

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20

Jilcott, Steven Wayne Jr. "Time-Dependent Perturbation and the Born-Oppenheimer Approximation." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/26814.

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We discuss the physical problem of a molecule interacting with an electromagnetic field pulse and model the problem using a time-dependent perturbation of the Born-Oppenheimer approximation to the Schrodinger equation. Using previous results that develop asymptotic series solutions in the Born-Oppenheimer parameter ε, we derive a formal Dyson series expansion in the perturbation parameter μ, which is proportional to the electromagnetic field strength. We then prove that this series is asymptotically accurate in both parameters, provided that the Hamiltonian for the electrons has purely discrete spectrum. Under more general hypotheses, we show that the series is accurate to first order in μ, and that it is accurate to one higher order if we place conditions on the abruptness of the EM pulse. We also show how this series development provides a justification for the Franck-Condon factors in the case of a diatomic molecule.
Ph. D.

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21

Huda, Gazi Mostafa. "EFFECT OF A SILICON TIP ON ABSORPTION CROSS SECTION, FIELD ENHANCEMENT, AND LOCALIZED SURFACE PLASMON RESONANCE OF DIFFERENT SIZED GOLD NANOPARTICLES UNDER EVANESCENT WAVE ILLUMINATION." UKnowledge, 2011. http://uknowledge.uky.edu/gradschool_theses/114.

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We have numerically investigated the influence of a nanoscale silicon tip in proximity to an illuminated gold nanoparticle. We describe how the position of the high-permittivity tip and the size of a nanoparticle impact the absorption, peak electric field and surface plasmon resonance wavelength under different illumination conditions. We detail the finite element method (FEM) approach we have used for this, whereby we specify a volume excitation field analytically and calculate the difference between this source field and the total field (i.e., scattered-field formulation). We show that a nanoscale tip can locally enhance the absorption of the particle as well as the peak electric field at length scales far smaller than the wavelength of the incident light.

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22

Carpino, Francesca. "Quadrupole Magnetic Field-Flow Fractionation: A Novel Technique For The Characterization Of Magnetic Particles." Cleveland, Ohio : Cleveland State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=csu1207595560.

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Thesis (Ph.D.)--Cleveland State University, 2008.
Abstract. Title from PDF t.p. (viewed on May 8, 2008). Includes bibliographical references (p. 121-126). Available online via the OhioLINK ETD Center. Also available in print.

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Alexeev, Arseny. "Quantum rings in electromagnetic fields." Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/8021.

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This thesis is devoted to optical properties of Aharonov-Bohm quantum rings in external electromagnetic fields. It contains two problems. The first problem deals with a single-electron Aharonov-Bohm quantum ring pierced by a magnetic flux and subjected to an in-plane (lateral) electric field. We predict magneto-oscillations of the ring electric dipole moment. These oscillations are accompanied by periodic changes in the selection rules for inter-level optical transitions in the ring allowing control of polarization properties of the associated terahertz radiation. The second problem treats a single-mode microcavity with an embedded Aharonov-Bohm quantum ring, which is pierced by a magnetic flux and subjected to a lateral electric field. We show that external electric and magnetic fields provide additional means of control of the emission spectrum of the system. In particular, when the magnetic flux through the quantum ring is equal to a half-integer number of the magnetic flux quantum, a small change in the lateral electric field allows tuning of the energy levels of the quantum ring into resonance with the microcavity mode, providing an efficient way to control the quantum ring-microcavity coupling strength. Emission spectra of the system are calculated for several combinations of the applied magnetic and electric fields.

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Torokoff, Kristel. "Field Theories and Vortices with Nontrivial Geometry." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Universitetsbiblioteket [distributör], 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-6744.

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25

Krug, Andreas. "Alkali Rydberg States in Electromagnetic Fields." Diss., lmu, 2001. http://nbn-resolving.de/urn:nbn:de:bvb:19-3362.

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Hsiang, Jen-Tsung. "Fluctuating electromagnetic fields and electron coherence /." Thesis, Connect to Dissertations & Theses @ Tufts University, 2004.

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Thesis (Ph.D.)--Tufts University, 2004.
Adviser: Lawrence H. Ford. Submitted to the Dept. of Physics. Includes bibliographical references (leaves 154-155). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

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27

Burke, Mary Joset. "Visualization of electromagnetic fields using MATLAB." Honors in the Major Thesis, University of Central Florida, 1998. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/25.

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This item is only available in print in the UCF Libraries. If this is your Honors Thesis, you can help us make it available online for use by researchers around the world by following the instructions on the distribution consent form at http://library.ucf.edu/Systems/DigitalInitiatives/DigitalCollections/InternetDistributionConsentAgreementForm.pdf You may also contact the project coordinator, Kerri Bottorff, at kerri.bottorff@ucf.edu for more information.
Bachelors
Engineering
Electrical Engineering

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Antonoyiannakis, Emmanuel (Manolis) Ioannou. "Electromagnetic fields and forces in nanostructures." Thesis, Imperial College London, 1998. http://hdl.handle.net/10044/1/37522.

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We have developed a general methodology for computing electromagnetic (EM) fields and forces in matter, based on solving the macroscopic Maxwell's equations numerically in real space and adopting the time-averaged Maxwell Stress Tensor formalism. Our approach can be applied to both dielectric and metallic systems characterised by a local frequency-dependent dielectric function, and in principle to any size and geometry. In this study we are particularly interested in calculating forces on nanostructures, induced by a beam of monochromatic light (such as a laser) of frequency w. These forces are the direct analogue of Van der Waals interactions at a single frequency: the presence of matter scatters the light and alters the EM field, resulting in an energy-change that manifests itself as a force. The motivation behind this particular direction is the facilitation of self-assembly in colloidal systems with the aim of aiding the fabrication of photonic crystals. In order to understand the main features of light-induced EM forces, as well as to provide a testbed for our numerical methodology, we first solve (analytically and numerically) for two homogeneous systems: a half-space and a slab. We find that in passing from a low-e to a high-e medium, the light beam always attracts the interface {i.e. the surface force is negative). The implication is that light will generally induce an attraction between the surfaces of two liquids separated by a layer of lower e. For attraction between solids there is a tougher requirement: the total force must also be negative. When the EM field is that of a travelling wave the total pressure is positive. In contrast, evanescent waves may cause the total pressure to become attractive (negative). Thus by shining evanescent light in the region between two solid bodies an attraction between them may be induced. We then study numerically the influence of monochromatic light (a travelling wave) on a crystal of dielectric spheres of GaP, concentrating on total forces induced on each sphere and on the crystal as a whole. We identify three regimes in the response of the system to radiation: • At large wavelengths the crystal may be approximated by a homogeneous slab with an effective permittivity eg//. The analytical results for reflectance and forces apply. • At wavelengths comparable to the lattice constant, multiple scattering effects tune in: when lo is inside the photonic band gaps the reflectivity of a thick crystalline slab rises to unity, the beam bounces off the crystal and there is a maximum momentum exchange (and largest forces). Also, a multitude of force orientations results when the Bragg conditions for multiple outgoing waves are met. • Much more interesting is the regime where the radiation couples to the E M eigenmodes supported by isolated spheres (Mie resonances). These modes are analogous to electronic orbitals and, like their electronic counterparts, can form bonding and anti-bonding interactions between neighbouring spheres. By irradiating the system with light at the bonding frequency an attractive interaction is induced between the spheres. The photo-induced attraction is strong; for a moderate I₀ ~ 3 x 10⁸ W/m² it surpasses all other interactions present (gravitational, thermal and Van der Waals) by 1-2 orders of magnitude. These resonant forces are sensitive to absorption, but, for GaP spheres in water (a common liquid medium for colloids), their effect should still be clearly seen, even for a polydispersion of a few percent. Thus we suggest that by judicious selection of bonding states we can drive a system towards a desired structure, rather than rely on the structure dictated by gravitational and Van der Waals forces. Apart from possible applications in the fabrication of 3D photonic crystals, the resonant mechanism leading to the bonding/anti-bonding effect may contribute to our understanding of novel non-linear phenomena arising due to the application of laser light fields in nanostructures.

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Mackman, Stephen William. "Gauge fields and quantum theory." Thesis, Durham University, 1996. http://etheses.dur.ac.uk/5183/.

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This thesis investigates the problems within quantum mechanics for the Bohm model caused by Lorentz invariance and the existence of photons. A model describing the electromagnetic interactions of fermions is produced which does not use photons and avoids these problems. It is then shown how these techniques can be extended to linearised gravitational interactions. Finally semi-classical gravity and the possibility of gravitationally induced collapse are considered. In the first part of the thesis two modifications to the Bohm model are proposed. One takes account of Lorentz invariance, and the other is capable of describing photons. The main part of the thesis is devoted to describing interactions in a way which does not need extra gauge particles, and so is in the same spirit as the Bohm model. Electromagnetic interactions are formed using a 4-potential operator which is calculated directly, without imposing commutation relations on the 4-potential. This leads to an expression for the 4-potential in terms of the Dirac field, and results in there being no photon states. There are various ways of constructing the theory and the scattering matrix of standard QED is compared to the scattering matrix of the version which appears to be most similar. Considering only the matrix elements between fermion states, they are found to be in agreement at the order e(^2), but disagree at the order e(^4). It follows that this model, which otherwise appears to be a self consistent theory of QED, cannot agree with experiment. The same techniques can be used to quantise General Relativity when it is linearised about the Minkowski metric. The metric operator is calculated in terms of the Dirac field. The interaction is similar to that of electrodynamics, being of order 4 in the Dirac field. Finally issues relating to gravitational collapse are discussed.

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Piwnicki, Paul. "Electromagnetic Fields in Moving and Inhomogeneous Media." Doctoral thesis, KTH, Alfvén Laboratory, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3270.

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The present thesis deals with electromagnetic effectscreated by the motion or inhomogeneity of a dielectricmedium.In the first paper the quantum R\"ontgen effect isdiscussed. Here a rotating Bose-Einstein condensate -- oranother kind of quantum fluid -- is placed in a chargedcapacitor. The medium's rotation creates a magnetic field.Quantum media can only rotate in form of vortices, which leadsto a magnetic field corresponding to the field of a magneticmonopole. In the remaining part of the thesis the geometricalrepresentation of electromagnetic fields in moving andinhomogeneous media is discussed. It is shown that aninhomogeneously moving dielectric, e.g., a vortex, defines aspace-time metric and light rays follow null-geodesics definedby this metric. This means that light propagation in a movingmedium is analogous to light propagation in a gravitationalfield. The possibility of creating laboratory models ofastronomical objects, e.g., black holes is discussed. Theapplicability of the newly developed media with extremely lowgroup velocity for the actual creation of such an experiment isconsidered. Furthermore, a model for the case of the slowlymoving medium is discussed. Here the light propagation isanalogous to the motion of a charged particle propagatingthrough a magnetic field. The velocity of the flow correspondsto the vector potential. Consequently, light propagation in avortex corresponds to the Aharonov-Bohm effect. Finally, acomplete geometrical description of light in an inhomogeneousdielectric at rest is presented. It is shown that lighttrajectories are geodesics of a three-dimensional metricdefined by the medium. Here even the propagation of the fieldsis discussed in the language of differential geometry and it isshown that the field vectors are parallel transported along therays. These considerations can be generalized to thefour-dimensional case where the field-strength tensor isparallel transported along the ray. This emphasizes thefar-reaching analogy between light in moving media and light ingravitational fields.

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Wallis, Alisdair Owen Garnett. "Ultracold molecules : the effect of electromagnetic fields." Thesis, Durham University, 2010. http://etheses.dur.ac.uk/184/.

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There is great interest within the physics and chemistry communities in the properties of ultracold molecules. Electromagnetic fields can be used to create, trap, and modify the collisional dynamics of ultracold molecules, and thus the properties of ultracold molecules in electromagnetic fields is of growing importance. This thesis examines some of the effects of externally applied electromagnetic fields on ultracold molecules. Initially, magnetic Feshbach resonances in combined electric and magnetic fields are examined in the collisions of He($^1S$)+SO($^3\Sigma^-$). Through detailed quantum scattering calculations, it is then shown that the sympathetic cooling of NH($^3\Sigma^-$) molecules with Mg atoms has a good prospect of success, a first for a neutral molecular system. Detailed quantum scattering calculations are performed for a wide range of collision energies and magnetic field strengths and it is found that the ratio of elastic to inelastic collisions is large for temperatures below 10 mK, and increases as the collision energy and magnetic field strength decrease. The near threshold collision properties of Mg+NH have been examined using a multichannel quantum defect theory approach. A new type of conical intersection, that is a function of applied electromagnetic fields only, is also demonstrated. For states of opposite parity, brought into degeneracy with a magnetic field, the degeneracy can be resolved by the addition of an electric field, forming a conical intersection. A suitable arrangement of fields could thus be used to create a conical intersection in laboratory coordinates within an ultracold trapped gas. For a Bose-Einstein condensate, in the mean-field approximation, the resultant geometric phase effect induces stable states of persistent superfluid flow that are characterized by half-integer quantized angular momentum.

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32

Khalid, M. "Exposure to electromagnetic fields from Wi-Fi." Thesis, University College London (University of London), 2011. http://discovery.ucl.ac.uk/1334466/.

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This thesis is concerned with the exposure of electromagnetic fields to school children from Wireless Local Area Networks (WLAN). The research provides insights into how wireless networks are implemented in schools, sets out to develop a systematic methodology to quantify field levels close to WLAN devices and then investigates the extent of exposure thereby assisting the Health Protection Agency (HPA) in providing advice. School children in the UK are being exposed to electromagnetic fields due to the increasing use of Wi-Fi technologies in schools. Many local government authorities and schools are facing difficulties in understanding the health issues associated with the use of WLAN networks and there is increasing pressure from parents to provide reassurance. There is lack of quantitative scientific data, and current methodologies do not provide a realistic measure of the extent of exposure. The results from the exploratory studies and the contribution from existing literature have then been synthesised to develop new methodologies. A set of measurements were made to come to an assessment of the level of radiofrequency fields adjacent to commonly used WLAN equipment. Finally, the way in which children interact with WLAN devices as part of their normal lessons was examined in determine the time averaged exposure. The outcome of this research is a robust measurement methodology and examination of extent of RF exposure to children which represents a significant contribution to the scientific knowledge. The measurement methodology has been demonstrated to be practicable and can be used with a range of wireless devices using pulsed signals and thus is capable of providing valuable information for future studies.

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33

Thurman, Hugh O. Copeland Gary E. "Neutron star electromagnetic field structure /." Connect to this resource. (Authorized users only), 2004.

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34

Laudrain, Antoine. "Layer Intercalibration of the ATLAS Electromagnetic Calorimeter and CP-odd Higgs Boson Couplings Measurements in the Four-Lepton Decay Channel with Run 2 Data of the LHC." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS341.

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Après la découverte du boson de Higgs en 2012 au LHC, l'intérêt s'est porté sur l'étude de ses propriétés pour vérifier le Modèle Standard et pour sonder la nouvelle physique. L'une de ses propriétés fondamentales est sa spin-parité (CP), dont le Modèle Standard prédit la valeur 0+. Les analyses menées sur les données récoltées au Run 1 du LHC ont rejeté toutes les hypothèses d'état pur de spin-parité autre que cette valeur. Cependant des états mixtes de CP sont toujours possibles, ce qui indiquerait une violation de symmétrie CP dans le secteur du Higgs.La première partie de cette thèse se concentre sur la calibration du calorimètre électromagnétique d'ATLAS permettant d'atteindre une résolution de l'ordre du pour mille sur l'énergie des électrons et photons, primordiaux dans les analyses du boson de Higgs. Une des étapes est l'inter-calibration des couches du calorimètre électromagnétique, corrigeant des effets résiduels de calibration électronique et de diaphonie (cross-talk). La méthode établie au Run 1 a montré ses limites devant les niveaux d'empilement mesurés au Run 2, et une nouvelle analyse a été alors dévéloppée, assurant le contrôle précis des incertitudes systématiques.La deuxième partie de cette thèse porte sur la mesure des couplages CP-impairs du boson de Higgs aux boson vecteurs, étudié dans le canal de désintégration du boson de Higgs en quatre leptons. Malgré une faible statistique, ce canal offre une signature propre et un rapport signal sur bruit de plus de deux, permettant l'analyse précise des propriétés du boson de Higgs. Le mode de production par fusion de bosons vecteurs offre la meilleure sensibilité aux effets de CP grâce à la présence de deux jets dans l'état final. La pollution venant du mode de production par fusion de gluon avec des jets additionels est réduite grâce à l'utilisation de réseaux neuronaux. Pour distinguer de manière univoque les effets CP-impair d'éventuels effets CP-pair encore inconnus, une nouvelle variable est construite dont l'asymétrie de forme dépend uniquement d'effets CP-impairs. Composée d'éléments de matrice, cette variable utilise les informations cinématiques du boson de Higgs et des jets de manière maximale. Les résultats sont interprétés en termes de théorie effective, et la sensibilité statistique à 68% de confiance sur le coefficient de Wilson tCzz est estimée à [-0.80, 0.80]
After the Higgs boson discovery at the LHC in 2012, interest turned to Higgs boson property measurements to refine the tests of the Standard Model and probe for new physics. One of its key properties is its spin-parity (CP), predicted to be 0+ in the Standard Model. Analyses of data collected during the Run 1 of the LHC rejected all pure spin-parity (CP) state other than 0+. However mixed CP states are still possible, and would indicate CP violation in the Higgs sector.The first part of this thesis focuses on the ATLAS electromagnetic calorimeter calibration, needed to reach a permil level on electron and photon energy resolution which are of prime importance for Higgs boson studies. One step of the calibration sequence consists of the layer intercalibration of the electromagnetic calorimeter, needed to correct residual electronics miscalibration and cross-talk effects. The Run 1 method has proven to be unreliable for the pileup levels in Run 2 and a new method was developed, ensuring a precise control on the systematic uncertainties.The second part of this thesis puts emphasis on the Higgs boson to vector boson CP-odd couplings, with the Higgs boson decaying to four leptons. This channel, despite low statistics, provides a clean signature and a signal-to-noise ratio over two, allowing for a precise determination of the Higgs boson properties. The vector boson fusion production channel offers the best sensitivity to CP effects thanks to its two characteristic tagging jets in the final state. The contamination from the gluon fusion production mode with additional jets is reduced using neural networks. To unambiguously distinguish yet unknown CP-even from possible CP-odd effects, a variable whose shape asymmetry only depends on CP-odd effects is built. This observable is based on the matrix element computation, maximally using the kinematic information available from Higgs boson and associated jets. Results are interpreted in a context of effective field theory, and the statistical precision on the tCzz Wilson coefficient is estimated to [-0.80, 0.80] at the 68% confidence level

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35

Pinchuk, 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.

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Direct solution for three dimensional electric or magnetic field vectors throughout the frequency spectrum is accomplished by a finite element formulation which includes displacement and conduction currents, and requires no special treatment for material interfaces. Analysis of bus bar and Bath cube eddy current problems demonstrate the capabilities of the method.
Spurious 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.

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36

Håkansson, Niclas. "Occupational exposure to electromagnetic fields and chronic diseases /." Stockholm, 2003. http://diss.kib.ki.se/2003/91-7349-719-3/.

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37

Kodali, Venkateswararao. "Characterization and analysis of close lightning electromagnetic fields." [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0000724.

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38

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

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

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Ani, Chinenye Jane. "Chaotic behaviour of charged particles in electromagnetic fields." Master's thesis, Faculty of Science, 2018. http://hdl.handle.net/11427/30058.

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In order to understand the motion of charged particles we numerically investigate the chaoticity of magnetic field lines of tokamak fields, as charged particles move along field lines. In particular, the symmetric tokamap was studied to determine the physical quantities that influence the system’s chaotic behaviour. We implement several chaos detection techniques: the construction of Poincaré maps, the computation of the maximum Lyapunouv characteristic exponent (mLCE), as well as the Smaller Alignment Index (SALI). The analyses performed showed that the mLCE and SALI methods accurately quantified magnetic field lines’ chaotic behaviour and that the relative perturbation strength influences the system’s chaoticity. In addition, we illustrate the diffusive properties of magnetic field lines, using statistical measures like the mean square displacement (MSD) and calculating diffusion coefficients. Lastly, we present the construction of explicit near-symplectic mappings of the symmetric tokamap with Lie-generating functions.

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Yaguchi, Hiroko. "Biological Effects and Psychosocial Implications of Electromagnetic Fields." Kyoto University, 2001. http://hdl.handle.net/2433/150736.

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Kyoto University (京都大学)
0048
新制・課程博士
博士(人間・環境学)
甲第9021号
人博第114号
12||116(吉田南総合図書館)
新制||人||28(附属図書館)
UT51-2001-F351
京都大学大学院人間・環境学研究科人間・環境学専攻
(主査)教授新宮一成, 教授池永満生, 教授杉万俊夫, 助教授宮越順二
学位規則第4条第1項該当

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41

Foo, Seng-Lee. "Analysis of electromagnetic fields in loaded TEM cells." Thesis, University of Ottawa (Canada), 1988. http://hdl.handle.net/10393/5170.

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42

Read, Smith Sarah Jane. "The effects of radiofrequency electromagnetic fields on cognition." Thesis, University of Surrey, 2007. http://epubs.surrey.ac.uk/843071/.

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The acute effects of radiofrequency electromagnetic fields (RF EMF) on human cognitive performance were investigated. Cognitive tasks were identified from RF EMF cognitive research; tests used most extensively were psychomotor performance, attention, working and episodic memory tasks. Review of published imaging research enabled selection of a battery of cognitive tasks for use in the experimental studies. Effects of practice and the test-retest reliabilities on the tests were evaluated and the relationship between the tests within the battery and measures of ability and personality investigated. Three studies were conducted to identify whether RF EMF produced by occupational communication systems had reliable effects on cognitive performance and self-reports of mood, anxiety and workload. Double-blind repeated measures design was used to investigate the following fields in comparison to sham; a high frequency (HF) 29MHz continuous wave (CW) signal, a very high frequency (VHF) 75MHz CW field, an Ultra High Frequency (UHF) modulated 448MHz field, a UHF 1206MHz CW signal and a TETRA 388MHz field pulse modulated at 17.6Hz. The first study demonstrated no significant effects of the VHF signal on performance when compared to sham. The HF signal appeared to reduce response time to two of the cognitive tasks and affect error rate on one of them. Investigation of the two UHF signals showed no reliable differences between conditions on the cognitive measures. The third study showed reliable differences between TETRA exposure and sham conditions on two of the tasks. Overall the results indicate that RF EMF signals at the frequencies and power levels used in these studies are well tolerated in healthy subjects. In general, the signals do not appear to have reliable and robust effects on human cognitive performance. However, there may be subtle transitory effects of RF EMF that are not well understood at the present time.

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Manuwong, Theerapatt. "Solidification of metal alloys in pulse electromagnetic fields." Thesis, University of Hull, 2015. http://hydra.hull.ac.uk/resources/hull:11671.

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This research studies the evolution of solidification microstructures in applied external physical fields including in a pulse electric current plus a static magnetic field, and a pulse electromagnetic field. A novel electromagnetic pulse device and a solidification apparatus were designed, built and commissioned in this research. It can generate programmable electromagnetic pulses with tuneable amplitudes, durations and frequencies to suit different alloys and sample dimensions for research at university laboratory and at synchrotron X-ray beamlines. Systematic studies were made using the novel pulse electromagnetic field device, together with finite element modelling of the multiphysics of the pulse electromagnetic field and microstructural characterisation of the samples made using scanning electron microscopy, X-ray imaging and tomography. The research demonstrated that the Lorentz force and magnetic flux are the dominant parameters for achieving the grain refinement and enhancing the solute diffusion. At a discharging voltage from 120 V, a complete equaxied dendritic structure can be achieved for Al-15Cu alloy samples, the strong Lorentz force not only disrupts the growing direction of primary dendrites, it is also enough to disrupts the growing directions of primary intermetallic Al2Cu phases in Al-35Cu alloy, resulting a refined solidification microstructures. The applied electromagnetic field also has significant effect on refining the eutectic structures and promoting the solute diffusion in the eutectic laminar structure. The research has demonstrated that the pulse electromagnetic field is a promising green technology for metal manufacture industry.

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Hamblin, Denise Lee. "The effect of mobile phone emitted electromagnetic fields on human brain activity and performance." Australasian Digital Thesis Program, 2006. http://adt.lib.swin.edu.au/public/adt-VSWT20061110.100936.

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Thesis (PhD) - Swinburne University of Technology.
Thesis for Doctor of Philosophy, Brain Sciences Institute, Faculty of Life and Social Sciences, Swinburne University of Technology - 2002. Typescript. Includes bibliographical references (p. 137-160).

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Tentor, Lawrence B. "Characterization of an Electromagnetic Tuned Vibration Actuator." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/27906.

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Tuned vibration absorbers (TVA) have been discussed in literature since the early twentieth century. These devices are implemented to suppress the systemâ s vibration by transferring energy to the absorber mass. This research examines an electromagnetic tuned vibration absorber that can have its tuned frequency altered by gap and current variation. The advantage of an adjustable TVA is that the system can be tuned to various excitation frequencies to cancel vibration. This research examines a unique embodiment using permanent magnets and an electromagnetic absorber to alter the system dynamics. The focus is to allow changes in tuned frequency to cancel system vibrations. This research develops the electromagnetic theory, presents absorber system simulations, and tests the dynamic absorberâ s response. The electromagnetic field is investigated to determine the field between a stationary magnet and the absorber electromagnet. This field can be numerically calculated as the superposition of four constituent fields. With the electromagnetic field determined, the force to displacement relation between the stationary magnet and the absorber electromagnet is calculated. The best fit is determined to be an inverse square relationship. Once the spring force relation is determined, the damping mechanisms are discussed and experiments proposed to isolate the different damping mechanisms. In the simulations, it is found that by having an adjustable electromagnetic TVA the natural frequency can be adjusted 2-3% with a +10 amp input and over 50% for a variable gap. The advantage of the variable gap is that it may be adjusted once and then no additional energy is needed, while the advantage of the variable current is that the system may be rapidly altered. The experiments are undertaken to test the constructed absorber for the spring and damping force. The tests confirm the spring force relation and quantify the high damping present in the tested configuration. Then the absorber system transfer functions are recorded. The absorber is then applied to a single degree of freedom system to verify its cancellation results by a gap variation.
Ph. D.

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46

Favaro, Alberto. "Recent advances in classical electromagnetic theory." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/10482.

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The early Sections of the present Thesis utilise a metric-free and connection-free approach so as derive the foundations of classical electrodynamics. More specifically, following a tradition established by Kottler [65], Cartan [14] and van Dantzig [137], Maxwell's theory is introduced without making reference to a notion of distance or parallel transport. With very few exceptions, the relevant concepts are derived from first principles. Indeed, Maxwell's theory is constructed starting from three experimentally justified axioms: (i) electric charge is conserved, (ii) the force acting on a test charge due to the electromagnetic field is the standard Lorentz one, (iii) magnetic flux is conserved. To be precise, a strictly deductive approach requires that three further postulates are introduced, as explained in the manual [41] by Hehl and Obukhov. Nevertheless, a shortened formalism is observed to be adequate for the purpose of this work. In nearly all cases, the electromagnetic medium is demanded to be local and linear. Moreover, the propagation of light is studied in the approximate geometrical optics regime. Lindell's astute derivation of the dispersion equation [80] is reformulated in the widespread mathematical language of tensor indices. The method devised in Ref. [80] is integrated with the analysis due to Dahl [16] of the space encompassing the physically viable polarisations. As a result, the geometry associated with the dispersion equation is investigated with considerable rigour. From the literature it is known that, to a great extent, the notion of distance can be viewed as a by-product of Maxwell's theory. In fact, imposing that the constitutive law is electric-magnetic reciprocal and skewon-free determines, albeit non-uniquely, a Lorentzian metric. A novel proof of this statement is examined. In addition, the unimodular forerunner of electric-magnetic reciprocity, defined in earlier works by Lindell [79] and Perlick [112], is shown to preserve the energy-momentum tensor.

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Sehatzadeh, Shayan. "Occupational exposure to electromagnetic fields and female breast cancer." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq29212.pdf.

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48

Berry, Yoke. "The effect of pulsed electromagnetic fields on protein unfolding." Access electronically, 2005. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20060713.142625/index.html.

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49

Tigga, Celine. "Modelling of Measurement Equipment for High Frequency Electromagnetic Fields." Thesis, Högskolan i Gävle, Avdelningen för elektronik, matematik och naturvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-18894.

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The aim of this thesis was to develop a model of a receiver which could be quickly used to analyze radiated interference levels from data captured at the output of the antenna equipment used to measure radiated energy. Active circuits were mainly used in developing this model for the ease with which the design and simulations could be carried out in OrCAD. The guiding document for the thesis work has been CISPR 16-1-1 (International Special Committee on Radio Interference part 16-1-1) which specifies the characteristics and performance of equipment for the measurement of radiated interference. The testing of this receiver model was carried out as far as possible based on the test setups recommended in CISPR, and all results have been compared with the standards laid down for the model. Using the results, it will be shown that a CISPR EMI receiver can be modeled as a simple EMI receiver consisting of filtering, mixing and detecting circuits built according to specifications.

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Culligan, Allan James. "The electromagnetic fields from a two-wire transmission line." Thesis, University of East Anglia, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267710.

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Dissertations / Theses on the topic 'Electromagnetic theory. Electromagnetic fields'

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