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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

An algorithm for the automatic resolution of the position, orientation and dipole moment of a magnetic dipole antenna buried in rock

Lishman, Ryan M 05 May 2008 (has links)
Abstract In this paper, an algorithm for accurately finding the position, orientation and dipole moment of a transmitting dipole antenna buried in rock is presented. The algorithm is based on simplified radiation equations that are shown to be valid within a region of space in the extreme near field surrounding the antenna called termed quasi-static region. Within this region, medium dependent propagation effects are negligible, allowing accurate, medium independent resolution of position, orientation and dipole moment. The magnetic field magnitude and direction values observed at a number of arbitrarily located points in space are used by the algorithm to generate a system of nonlinear equations. This system of equations is solved using a simultaneous multi-variable Newton-Raphson solver with line searches and backtracking providing a measure of global convergence. An additional method, based on an iterated random search, further improves the global convergence capability of the algorithm. If the dipole moment of the transmitting antenna is known, measurements from two observer points are sufficient to resolve the position and orientation of the dipole. If the dipole moment is unknown, three observer points are required to solve for the unknown position, orientation and dipole moment. The algorithm is able to find an exact solution using exact theoretical measurements, and a minimised least squares solution where measurements are subject to noise. The theory relating to the algorithm is discussed including distance-frequency relations for the quasistatic region of a number of common rock types. Probabilistic modelling, simulation and test results of the algorithm are also included.
2

Target Tracking using Maxwell’s Equations / Målföljning med Maxwells ekvationer

Wahlström, Niklas January 2010 (has links)
<p>Starting from Maxwell’s equations, we derive a sensor model for three-axis magnetometerssuitable for localization and tracking applications. The model dependson the relative position between the sensor and the target, orientation of the targetand its magnetic signature. Both point targets and extended target modelsare provided. The models are validated on data taken from various road vehicles.The suitability of magnetometers for tracking is analyzed in terms of local observabilityand Cramér Rao lower bound as a function of the sensor positions in atwo sensor scenario. Also the signal to noise ratio is computed to determine theeffective range of the magnetometer. Results from field test data indicate excellenttracking of position and velocity of the target, as well as identification of themagnetic target model suitable for target classification.</p><p> </p>
3

Target Tracking using Maxwell’s Equations / Målföljning med Maxwells ekvationer

Wahlström, Niklas January 2010 (has links)
Starting from Maxwell’s equations, we derive a sensor model for three-axis magnetometerssuitable for localization and tracking applications. The model dependson the relative position between the sensor and the target, orientation of the targetand its magnetic signature. Both point targets and extended target modelsare provided. The models are validated on data taken from various road vehicles.The suitability of magnetometers for tracking is analyzed in terms of local observabilityand Cramér Rao lower bound as a function of the sensor positions in atwo sensor scenario. Also the signal to noise ratio is computed to determine theeffective range of the magnetometer. Results from field test data indicate excellenttracking of position and velocity of the target, as well as identification of themagnetic target model suitable for target classification.
4

Effects of magnetic field models on control of electromagnetic actuators

Son, Hungsun 14 November 2007 (has links)
Many applications such as automobiles, gyroscopes, machine tools, and transfer systems require orientation control of a rotating shaft. Demands for multi-degree of freedom (DOF) actuators in modern industries have motivated this research to develop a ball-joint-like, brushless, direct-drive spherical wheel motor (SWM) that offers a means to control the orientation of its rotating shaft. This thesis presents a general method for deriving a closed-form magnetic field solution for precise torque calculation. The method, referred here as distributed multi pole (DMP) modeling, inherits many advantages of the dipole model originally conceptualized in the context of physics, but provides an effective means to account for the shape and magnetization of the physical magnet. The DMP modeling method has been validated by comparing simulated fields and calculated forces against data obtained experimentally and numerically; the comparisons show excellent agreement. The DMP models provide a basis to develop a non-contact magnetic sensor for orientation sensing and control of a rotating shaft. Three controllers have been designed and experimentally implemented for the SWM; open-loop and PD with/without an observer. The OL control system, which decouples the spin from the shaft inclination, provides the fundamental design structure for the SWM and serves as a basis for designing feedback controllers with/without an observer. While the observer and controller designs have been developed in the context of a spherical wheel motor, these techniques along with the models and analysis tools developed in this research can be applied to design, analysis and control of most electromagnetic devices. We expect that the analytical method along with the orientation sensor and spherical wheel motor will have broad spectrum of applications.
5

Electron and muon anomalous magnetic dipole moment in the 3-3-1 model with heavy leptons / O momento de dipolo magnético anômalo do elétron e do múon no modelo 3-3-1 com léptons pesados

Santos, George de Conto 09 March 2018 (has links)
Submitted by GEORGE DE CONTO SANTOS null (georgedc@ift.unesp.br) on 2018-03-26T19:09:38Z No. of bitstreams: 1 Tese_doutorado.pdf: 1257592 bytes, checksum: 301d08e8373f7f6aeb4a2e0ce8f9f637 (MD5) / Approved for entry into archive by Hellen Sayuri Sato null (hellen@ift.unesp.br) on 2018-03-29T16:17:42Z (GMT) No. of bitstreams: 1 decontosantos_g_dr_ift.pdf: 1257592 bytes, checksum: 301d08e8373f7f6aeb4a2e0ce8f9f637 (MD5) / Made available in DSpace on 2018-03-29T16:17:42Z (GMT). No. of bitstreams: 1 decontosantos_g_dr_ift.pdf: 1257592 bytes, checksum: 301d08e8373f7f6aeb4a2e0ce8f9f637 (MD5) Previous issue date: 2018-03-09 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Nós calculamos, no contexto do modelo 3-3-1 com léptons pesados carregados, vínculos sobre alguns dos parâmetros das partículas extras do modelo ao impor que suas contribuições aos fatores (g-2) do elétron e do múon estejam de acordo com os dados experimentais dentro de 1 sigma - 3 sigma. Para obter resultados realistas nós consideramos algumas das possíveis soluções das matrizes unitárias esquerda e direita que diagonalizam as matrizes de massa leptônicas, dando as massas leptônicas observadas e ao mesmo tempo acomodando a matriz de mistura de Pontecorvo-Maki-Nakagawa-Sakata (PMNS). Nós mostramos que, ao menos até a ordem de 1-loop, na faixa de parâmetros explorada, não é possível acomodar simultaneamente os fatores (g-2) do elétron e do múon a não ser que um dos léptons extras tenha massa da ordem de 20-40 GeVs e a escala de energia da simetria 331 esteja em torno de 60-80 TeVs. / We calculate, in the context of the 3-3-1 model with heavy charged leptons, constraints on some parameters of the extra particles in the model by imposing that their contributions to both the electron and muon (g-2) factors are in agreement with experimental data up to 1 sigma - 3 sigma. In order to obtain realistic results we use some of the possible solutions of the left- and right- unitary matrices that diagonalize the lepton mass matrices, giving the observed lepton masses and at the same time allowing to accommodate the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) mixing matrix. We show that, at least up to 1-loop order, in the particular range of the space parameter that we have explored, it is not possible to fit the observed electron and muon (g-2) factors at the same time unless one of the extra leptons has a mass of the order of 20-40 GeVs and the energy scale of the 331 symmetry to be of around 60-80 TeVs. / 152740/2014-7
6

Performance Analysis of Point Source Model with Coincident Phase Centers in FDTD

Xu, Yang 16 April 2014 (has links)
The Finite Difference Time Domain (FDTD) Method has been a powerful tool in numerical simulation of electromagnetic (EM) problems for decades. In recent years, it has also been applied to biomedical research to investigate the interaction between EM waves and biological tissues. In Wireless Body Area Networks (WBANs) studies, to better understand the localization problem within the body, an accurate source/receiver model must be investigated. However, the traditional source models in FDTD involve effective volume and may cause error in near field arbitrary direction. This thesis reviews the basic mathematical and numerical foundation of the Finite Difference Time Domain method and the material properties needed when modeling a human body in FDTD. Then Coincident Phase Centers (CPCs) point sources models have been introduced which provide nearly the same accuracy at the distances as small as 3 unit cells from the phase center. Simultaneously, this model outperforms the usual sources in the near field when an arbitrary direction of the electric or magnetic dipole moment is required.
7

Soluções analíticas para o acoplamento de um fluido e um dipolo magnético massivo em relatividade geral / Analytical solutions for a fluid coupled to a magnetic massive dipole in general relativity

Diaz Polanco, Jose Luis Bernardo 05 September 2008 (has links)
Orientador: Patricio Anibal Letelier Sotomayor / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-10T14:48:16Z (GMT). No. of bitstreams: 1 DiazPolanco_JoseLuisBernardo_D.pdf: 1702870 bytes, checksum: b78c0c03a9b2631b73aa3127ce3e7c0b (MD5) Previous issue date: 2008 / Resumo: Apresentamos duas soluções analíticas das equações de Einstein: A primeira para o caso estático no qual um fluido carregado está em torno de um corpo massivo com propriedades magnétic~ do tipo dipolar. Esta solução se reduz à solução de Gutsunaev-Manko [Ts.I. Gutsunaev , V .8. Manko Phys. Lett. 5, 215, 19851 se o fluido carregado desaparece. Encontramos que o balanço entre os campos acoplados é devido à existência de fluxos de energia (térmica e eletromagnética) auto-compensados. A pressão de radiação compensa os efeitos dinâmicos do fluido ao redor do corpo central. Estudamos os fluxos de energia no sistema e suas propriedades termodinâmicas. Encontramos o estado termodinâmico do sistema. Esta solução contém a solução de 8chwarzschild como caso particular . A segunda solução descreve um dipolo magnético massivo e irradiante. Esta solução é dependente do tempo e descrevemos cada uma das grandezas que participam na solução. Analisamos os fluxos de energia do sistema e notamos que a radiação do dipolo diminui com o tempo chegando num estágio final do tipo dipolo magnético massivo no vácuo. Torna-se interessante pensar na possibilidade de observação destes fluxos de energia na vizinhança de objetos estrelares compactos com propriedades magnéticas extremas / Abstract: We derive analytical solutions of the Einsteinfs equations for two different cases: The first one, a static case, in which a charged fluid is around a mass with extreme magnetic properties of the dipole type. This solution reduces to the Gutsunaev-Manko solution [Ts.I. Gutsunaev , V .S. Manko Phys. Lett. 5, 215, 19851 in the abscense of the charged fluid. We found that the gravitational equilibrium of the system is achieved when the energy fluxs ( thermal and electromagnetic) are balanced and the effective radiation pressure compensates the gravitational effects in the fluid. We study the flows of energy in the system and their thermodynamics properties, we found an analytical expression for the thermodynamic state of the coupled systems. This solution contains the Schwarzschild solution as a particular case. The second solution describes a massive magnetic dipole emiting radiation decreasing in time. In this case we also found the thermodynamic state of the system. As a conclusion, we believe that our theoretical model can be applied to compact stellar systems with extreme magnetic properties / Doutorado / Relatividade e Gravitação / Doutor em Ciências
8

Detectors developments for the UA9 experiment at the CERN SPS / Développement de détecteurs pour l'expérience UA9 au CERN SPS

Natochii, Andrii 13 September 2019 (has links)
Les travaux de recherche documentés dans cette thèse s'inscrivent dans le cadre de la Collaboration UA9 au CERN. L'objectif principal de la collaboration est l'étude de la collimation et de l'extraction de faisceaux de particules de haute énergie. La thèse est principalement consacrée au développement des détecteurs et aux installations expérimentales correspondantes qui ont été mises en œuvre au SPS et au LHC au CERN. En ce qui concerne la nature de l'interaction des particules chargées avec une structure monocristalline, un cristal courbé peut être utilisé pour orienter le faisceau de particules de haute énergie au moyen de la canalisation de particules entre les plans atomiques du cristal. Un tel phénomène est étudié de manière approfondie par la Collaboration UA9. Un des principaux objectifs de la recherche présentée dans cette thèse est de développer des dispositifs sensibles pour mesurer le flux et les caractéristiques de faisceau des particules déviées par le cristal au SPS et au LHC. Pour cette thèse nous avons étudié les détecteurs Cherenkov (CpFM) et les détecteurs à pixel (Timepix). Depuis 2015, le CpFM (détecteur de Cherenkov pour la mesure du flux de protons) a été souvent modifié afin d'améliorer la précision pour le comptage des particules. La plage de fonctionnement du dispositif varie de 1 à 1000 particules par faisceau de particules (~3 ns) avec une résolution inférieure à 20% par proton. Fonctionnant dans le vide primaire de l’accélérateur et à des doses de rayonnement élevées, le détecteur a montré une grande stabilité et ayant la possibilité d’effectuer des études de contamination par faisceau. À son tour, le détecteur Timepix a été étalonné sur la ligne de faisceaux d'extraction de l'accélérateur SPS, fonctionnant dans le vide secondaire (Roman Pot). Une partie importante de la thèse est consacrée à la caractérisation et à l'étalonnage de ces détecteurs avec les développements des logiciels pour l'acquisition et l'analyse de données. Dans cette thèse, nous proposons également la mesure du moment dipolaire magnétique (MDM) de baryons à courte durée de vie. Le MDM est une caractéristique importante de l'interaction des particules avec un champ magnétique externe. Pour cette thèse, nous nous concentrons sur la mesure le MDM du baryon LambdaC+, qui pourrait fournir des informations sur le facteur gyromagnétique (g) du quark charme. Une valeur différente de g=2 indiquera une structure composite possible du c-quark et clairement la présence de physique au-delà du Modèle Standard (SM). Jusqu'ici, aucune mesure expérimentale du moment dipolaire magnétique des baryons avec des quarks lourds n'a été effectuée en raison d'une courte durée de désintégration de ces particules (environ 60 um). La proposition faite dans cette thèse est de produire des baryons charmés par interaction forte entre les protons extraits (à l’aide d’un premier cristal courbé) et une cible. Après la cible, un deuxième cristal courbé à grand angle (de plusieurs mrad) est utilisé pour canaliser les baryons et induire une rotation du vecteur de polarisation des baryons charmés. Cette configuration s'appelle une configuration à double cristal et l'expérience est proposée au LHC. Dans cette thèse, je me suis concentré principalement sur tous les tests et la validation nécessaires au SPS avant la mise en œuvre au LHC. Une configuration expérimentale possible pour les mesures MDM au niveau du SPS est également proposée avec une estimation de l'erreur absolue de la valeur mesurée du facteur g pour le baryon LambdaC+. / The research work documented in this thesis is done in a frame of the UA9 Collaboration at CERN. The main goal of the collaboration is the investigation of the high-energy particle beam collimation and extraction. The thesis is mainly devoted to the developments of detectors and the consequent experimental setups implemented at the SPS or LHC circulating machines at CERN. Regarding the nature of the charged particle interaction with a monocrystalline structure, a curved crystal can be used for the steering of the high-energy particle beam by means of the particle channeling between atomic planes of the crystal. Such a phenomenon is intensively studied by the UA9 Collaboration. Therefore, one of the main goals of the presented research is to develop sensitive devices for measuring the flux and the beam characteristics of the particles deflected by the crystal at the circulating machines. The detectors studied for this thesis are Cherenkov (CpFM) and pixel (Timepix). Since 2015, the CpFM (Cherenkov detector for proton Flux Measurement) has undergone various modifications to improve the particle counting characteristics. The range of the device operation varies from 1 to 1000 particles per bunch (~3 ns) with the particle resolution of less than 20% per single proton. Working in the primary vacuum of the accelerator and at high radiation doses, the detector showed high stability with the possibility to perform beam contamination studies. In turn, the Timepix detector has been calibrated at the extraction beamline and SPS accelerator, working in the secondary vacuum of the Roman Pot. A significant part of the thesis is devoted to the characterization and calibration of these detectors with the software developments for data acquisition and analysis. In this thesis, we also make a proposal for the measurement of the magnetic dipole moment (MDM) of short-lived baryons. The MDM is an important characteristic of the particle interaction with an external magnetic field. For the thesis, we concentrate on the measurement of the LambdaC+ MDM, which could provide information on the gyromagnetic (g) factor of the charm quark. Any discrepancy from g=2 will indicate a possible composite structure of the c-quark and clearly physics beyond the Standard Model (SM). So far, no experimental measurements of this value of baryons with heavy flavoured quarks have been carried out due to a short decay length of these particles (about 60 um). The proposal made in this thesis is to produce charm baryons by a strong interaction of the extracted proton beam (using a first bent crystal) impinging onto a target followed by the second large angle bent crystal (of several mrad) to channel the baryons and to rotate their polarization vector. This configuration is called a double-crystal setup and the experiment is proposed to take place at the LHC. In this thesis, I concentrate mainly on all the tests and validation needed at the SPS prior to the implementation at the LHC. A possible experimental configuration for the MDM measurements at the SPS is also proposed with an estimation of the absolute error of the measured g-factor value for the LambdaC+ baryon.
9

Determination and compensation of magnetic dipole moment inapplication for a scientific nanosatellite mission

Jéger, Csaba January 2017 (has links)
SEAM (Small Explorer for Advanced Missions) is a 3U CubeSat developedat KTH Royal Institute of Technology which will provide highqualityDC and AC magnetic field measurements of Earth’s magneticfield. The measurement system requires extended periods of timeup to 1000 seconds without active attitude control. The satellite willuse passive gravity gradient stabilization and dipole cancellation via aseparate set of magnetorquers to satisfy LVLH pointing requirementsduring the coasting phases. In this thesis a detailed model of satellitemagnetic moment is presented which includes dipole moment sourcesfrom on-board current loops. The attitude dynamics of the satelliteis characterized with simulations and a strategy is proposed to estimateand compensate the time-dependent magnetic dipole momentusing the dipole compensation magnetorquers and an offline estimationalgorithm. The algorithm is tested with simulated error sourcesand noise and was found to be able to robustly identify and cancel outthe satellite dipole to satisfy mission requirements. / SEAM (Small Explorer for Advanced Missions) är en 3U CubeSat utveckladpå KTH Kungliga tekniska högskolan för DC och AC magnetiskfältmätningarav Jordens magnetfält. Mätningar kräver längretidperioder upp till 1000 sekunder utan aktiv attitydstyrning. Satellitenkommer använda passiv tyngdkraftsgradientstabilisering samtmagnetisk dipolmomentkompensation med hjälp av ett separat setav magnetiska spolar för att upprätthålla orienteringskrav under perioderutan attitydstyrning. Denna rapport presenterar en detaljeradmodell av satellitens magnetiskt dipolmoment som inkluderar dipolmomentkällorfrån strömslingor ombord satelliten. Satellitens attityddynamikär karaktäriserad med simulationer och en strategi tas framför att estimera och kompensera det tidsberoende magnetiska dipolmomentetgenom att använda dipolkompensations magnetiska spolaroch en offline estimeringsalgoritm. Algoritmen är testad med simuleradefelkällor och brus och har funnits pålitlig för uppskattning avdipolmomentet och dess kompensation för att uppfylla missionskrav.
10

Properties Of Light And Heavy Baryons In Light Cone Qcd Sum Rules Formalism

Azizi, Kazem 01 March 2009 (has links) (PDF)
In this thesis, we investigate the masses, form factors and magnetic dipole moments of some light octet, decuplet and heavy baryons containing a single heavy quark in the framework of the light cone QCD sum rules. The magnetic dipole moments can be measured considering radiative transitions within a multiplet or between multiplets. Analyzing the transitions among the baryons and calculating the above mentioned parameters can give us insight into the structure of those baryons. In analyzing the aforementioned processes, the transition form factors play a crucial role. In this thesis, the form factors for these transitions are calculated using the light cone QCD sum rules approach. In the limit when the light quark masses are equal, mu = md = ms, QCD has an SU(3) flavour symmetry which can be used to classify the light baryons. This classification results in the light decuplet, octet and singlet baryons. The baryons containing single heavy quark, on the other hand, can be classified according to the spin of the light degrees of freedom in the heavy quark limit, mQ -&gt / infinity. QCD at low energies, when the baryons are formed, is a non-perturbative theory. Hence, for phenomenology of the baryons, the QCD sum rules as a more powerful non-perturbative approach is used. Understanding the properties of nucleons is one of the main objectives of QCD. To investigate the properties of the nucleons, the axial N-Delta(1232) transition form factors are calculated within the light cone QCD sum rules method. A comparison of our results on those form factors with the predictions of lattice QCD and quark model is presented. The nucleon electromagnetic form factors are also calculated in the same framework using the most general form of the nucleon interpolating current. Using two forms of the distribution amplitudes (DA&rsquo / s), predictions for the form factors are presented and compared with existing experimental data. It is shown that our results describe the existing experimental data remarkably well. Another important property of the baryons is their magnetic moments. The magnetic moments of the heavy Xi_Q (Q = b or c) baryons containing a single charm or bottom quark are calculated within the light cone QCD sum rules approach. A comparison of our results with the predictions of other approaches, such as relativistic and nonrelativistic quark models, hyper central model, Chiral perturbation theory, soliton and skyrmion models is presented. Moreover, inspired by the results of recent experimental discoveries for charm and bottom baryons, the masses and magnetic moments of the heavy baryons with J^2P = 3/2^+ containing a single heavy quark are studied also within the light cone QCD sum rules method. Our results on the masses of heavy baryons are in good agreement with predictions of other approaches, as well as with the existing experimental values. Our predictions on the masses of the states, which are not experimentally discovered yet, can be tested in the future experiments. A comparison of our results on the magnetic moments of these baryons and the hyper central model predictions is also presented.

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