Une géométrie d'éprouvette tubulaire de traction-torsion entaillée a été optimisée pour caractériser l'effet de l'état des contraintes (triaxialité et paramètre de Lode) sur la ductilité des métaux à faible taux de triaxialité. Des essais biaxiaux proportionnels ou non, accompagnés de mesures des champs cinématiques par stéréo-corrélation d'images ont été réalisés sur un acier 36NiCrMo16 revenu et un alliage d'aluminium 2024-T351. Les trajets de chargement à rupture (évolution au point critique de la déformation plastique équivalente, de la triaxialité des contraintes et du paramètre de Lode) ont été obtenus. L'évolution de la ductilité de l'alliage d'aluminium en fonction de la triaxialité obtenue en traction-torsion diffère notablement de celle obtenue par Bao et Wierbicki en 2004 qui suggérait une ductilité minimale en cisaillement, tandis que la technique de traction-torsion révèle une ductilité maximale en cisaillement. Un effet notable des trajets de chargement non monotones ou non proportionnels sur la ductilité a été mis en évidence au moyen d'essais séquentiels composés d'un pré-chargement en compression, torsion ou traction, suivi d'une séquence de chargement proportionnel en traction-torsion combinées. Des observations au MEB de coupes métallographiques à l'issue d'essais biaxiaux interrompus, ainsi qu'un suivi en temps réel de la déformation et de l'endommagement en surface, lors d'essais de torsion dans le MEB et un essai de fissuration couplé à un suivi 3D de l'endommagement par laminographie sous rayonnement synchrotron ont mis en évidence des phénomènes de localisation à de multiples échelles ainsi que la croissance de certaines cavités, même en cisaillement pur, qui contraste avec l'affaissement total prédit par les modèles de cellule élémentaire. Ceci semble lié à l'allongement axial significatif mesuré en torsion pure (effet Swift). La localisation par cisaillement apparaît comme le mécanisme prédominant de coalescence des cavités, ce qui justifie l'adoption d'un critère d'initiation de la rupture de type Hosford-Coulomb. Utilisé en conjonction avec un indicateur non-linéaire d'endommagement il permet de rendre compte des ductilités mesurées, y compris sous chargement potentiellement non-proportionnel.

This dissertation consists of two parts and investigates the crustal deformation associated with great subduction zone earthquake at two different spatial scales. At the small scale, I investigate the stress transfer along the megathrust during great earthquakes and its effects on the forearc wedge. At the large scale, I investigate the viscoelastic crustal deformation of the forearc and the back arc associated with great earthquakes. Part I: In a subduction zone, the frontal region of the forearc can be morphologically divided into the outer wedge and the inner wedge. The outer wedge which features much active plastic deformation has a surface slope angle generally larger than that of the inner wedge which hosts stable geological formations. The megathrust can be represented by a three-segment model, the updip zone (velocity-strengthening), seismogenic zone (velocity-weakening), and downdip zone (velocity-strengthening). Our dynamic Coulomb wedge theory postulates that the outer wedge overlies the updip zone, and the inner wedge overlies the seismogenic zone. During an earthquake, strengthening of the updip zone may result in compressive failure in the outer wedge. The inner wedge undergoes elastic deformation. I have examined the geometry and mechanical processes of outer wedges of twenty-three subduction zones. The surface slope of these wedges is generally too high to be explained by the classical critical taper theory but can be explained by the dynamic Coulomb wedge theory. Part II: A giant earthquake produces coseismic seaward motion of the upper plate and induces shear stresses in the upper mantle. After the earthquake, the fault is re-locked, causing the upper plate to move slowly landward. However, parts of the fault will undergo continuous aseismic afterslip for a short duration, causing areas surrounding the rupture zone to move seaward. At the same time, the viscoelastic relaxation of the earthquake-induced stresses in the upper mantle causes prolonged seaward motion of areas farther landward including the forearc and the back arc. The postseismic and interseismic crustal deformation depends on the interplay of these three primary processes. I have used three-dimensional viscoelastic finite element models to study the contemporary crustal deformation of three margins, Sumatra, Chile, and Cascadia, that are presently at different stages of their great earthquake cycles. Model results indicate that the earthquake cycle deformation of different margins is governed by a common physical process. The afterslip of the fault must be at work immediately after the earthquake. The model of the 2004 Sumatra earthquake constrains the characteristic time of the afterslip to be 1.25 yr. With the incorporation of the transient rheology, the model well explains the near-field and far-field postseismic deformation within a few years after the 2004 Sumatra event. The steady-state viscosity of the continental upper mantle is determined to be 10^19 Pa S, two orders of magnitude smaller than that of the global value obtained through global postglacial rebound models. / Graduate

Recent developments in the field of nanotechnology allowed the access to adequate length scale necesary to closely investigate spins and opened large prospects of using electrons spin degree of freedom in new generation electronic devices. This have lead to the development of a vibrant field dubbed spintronics.Here, we present experiments that combine two very promising materials: namely cardon nanotubes and palladium-nickel (PdNi), with the purpose to manipulate the electronic spin both in the classical and in the quantum regime. We implement a quantum dot connected to two non-collinear ferromagnetic leads that acts as a spin-valve device. The versatility of carbon nanotubes to fabricate quantum dots when connected to PdNi electrodes via tunneling barriers is combined with the particular transversal anisotropy of the PdNi when shaped in nanometric stripes.For devices exploiting actively the electronic spin, however control over classical or quantum spin rotations has still to be achieved. A detailed understanding of the magnetic characteristics of PdxNi 100-x alloy is crucial both for understanding the switching characteristics of such the spin-valve device and for optimizing its electronic properties. We present a magnetic study of Pd20Ni80 and Pd90Ni10 nanostripes by means of extraordinary Hall effect measurements, at low temperature, for various dimensions, thicknesses and capping films. In the case of Pd20Ni80, this experiment is a first at low temperature.The CNT-based device proposed here was tested both in linear and nonlinear transportregimes. While the linear spin dependent transport displays the usual signatures of electronicconfinement, the finite bias magnetoresistance displays an impressive magnetoresistance antisymmetric reversal in contrast with the linear regime. This effect can only be understood if electronic interactions are considered. It is accompanied by a linear dispersion of the zeromagnetoresistance point in the bias-field plane. Simulations based on a proposed model confirm a current induced spin precession, electrically tunable due to the quantum nature ofthe device.

This dissertation consists of two parts and investigates the crustal deformation associated with great subduction zone earthquake at two different spatial scales. At the small scale, I investigate the stress transfer along the megathrust during great earthquakes and its effects on the forearc wedge. At the large scale, I investigate the viscoelastic crustal deformation of the forearc and the back arc associated with great earthquakes. Part I: In a subduction zone, the frontal region of the forearc can be morphologically divided into the outer wedge and the inner wedge. The outer wedge which features much active plastic deformation has a surface slope angle generally larger than that of the inner wedge which hosts stable geological formations. The megathrust can be represented by a three-segment model, the updip zone (velocity-strengthening), seismogenic zone (velocity-weakening), and downdip zone (velocity-strengthening). Our dynamic Coulomb wedge theory postulates that the outer wedge overlies the updip zone, and the inner wedge overlies the seismogenic zone. During an earthquake, strengthening of the updip zone may result in compressive failure in the outer wedge. The inner wedge undergoes elastic deformation. I have examined the geometry and mechanical processes of outer wedges of twenty-three subduction zones. The surface slope of these wedges is generally too high to be explained by the classical critical taper theory but can be explained by the dynamic Coulomb wedge theory. Part II: A giant earthquake produces coseismic seaward motion of the upper plate and induces shear stresses in the upper mantle. After the earthquake, the fault is re-locked, causing the upper plate to move slowly landward. However, parts of the fault will undergo continuous aseismic afterslip for a short duration, causing areas surrounding the rupture zone to move seaward. At the same time, the viscoelastic relaxation of the earthquake-induced stresses in the upper mantle causes prolonged seaward motion of areas farther landward including the forearc and the back arc. The postseismic and interseismic crustal deformation depends on the interplay of these three primary processes. I have used three-dimensional viscoelastic finite element models to study the contemporary crustal deformation of three margins, Sumatra, Chile, and Cascadia, that are presently at different stages of their great earthquake cycles. Model results indicate that the earthquake cycle deformation of different margins is governed by a common physical process. The afterslip of the fault must be at work immediately after the earthquake. The model of the 2004 Sumatra earthquake constrains the characteristic time of the afterslip to be 1.25 yr. With the incorporation of the transient rheology, the model well explains the near-field and far-field postseismic deformation within a few years after the 2004 Sumatra event. The steady-state viscosity of the continental upper mantle is determined to be 10^19 Pa S, two orders of magnitude smaller than that of the global value obtained through global postglacial rebound models. / Graduate

The main purpose of this study is to compare the effects of the Multiple Intelligences based instruction versus traditional instruction on ninth grade students&#039 / physics achievement. MI inventory, Attitude Scale Toward the Content &ldquo / Coulomb&rsquo / s Law&rdquo / , Multiple Choice Physics Achievement test on the content &ldquo / Coulomb&rsquo / s Law&rdquo / , and MI based Physics Achievement rubric were used as measuring tools. The study was conducted with 268 ninth grade public high school students in Sincan district in the spring semester 2002-2003. There were two teachers and their eight classes in this study. MI inventory, Attitude Toward the Content &ldquo / Coulomb&rsquo / s Law&rdquo / , and Multiple Choice Physics Achievement test were administered as pretest to both experimental and control groups. Then, students in experimental groups were iv exposed to the MI based lessons. Students in experimental classes were grouped with respect to the students&rsquo / strongest intelligences in Verbal/Linguistic, Logical/Mathematical, Visual/Spatial, Interpersonal intelligence dimensions. In control groups, traditional teaching method was used. After three weeks treatment, all the students were posttested with the same tests. In experimental groups, students&rsquo / MI based physics achievement was measured on the last treatment week. The data were analyzed using SPSS by multivariate analyses of covariance (MANCOVA). According to the results of this study, multiple intelligences based instruction made significant effect on students&rsquo / physics achievement on the content &ldquo / Coulomb&rsquo / s Law&rdquo / with respect to the traditional method. However, multiple intelligences based instruction showed no significant effect on students&rsquo / physics attitude toward the content &ldquo / Coulomb&rsquo / s Law&rdquo / with respect to the traditional method.

Ces dernières années, de considérables efforts expérimentaux ont été dévoués au développement d’outils de nanoélectronique quantique, dans le but d’atteindre un niveau de contrôle sur le transport électronique quantique à l’échelle de l’électron unique. Ces avancées ont poussé à un changement de paradigme dans le domaine du transport électronique cohérent et donné naissance à l’optique quantique électronique, domaine dans lequel cette thèse s’inscrit. Cette thèse est consacrée à deux problématiques. Tout d’abord, elle s’intéresse au problème des interactions Coulombiennes entre électrons, qui donnent lieu à un phénomène de décohérence qu’il est nécessaire de caractériser et de prédire au mieux afin de le contrôler. En utilisant une approche analytique et numérique, il a été possible de prédire l’effet de ces interactions sur un système expérimentalement accessible, prédiction qui a ensuite été confirmée par l’expérience. Dans la foulée de ce résultat, cette thèse présente des possibilités de contrôle de ces interactions, et propose un moyen de les mettre en œuvre qui devrait pouvoir être testé dans une expérience. Je me suis également confronté à la problématique de la caractérisation d’états quantiques complexes. En particulier, suite à la démonstration expérimentale d’un protocole de tomographie pour des états mono-électroniques, je me suis tourné vers l’extension de ce protocole à des états plus complexes, pouvant exhiber des propriétés de cohérence à deux électrons, voire plus. Ces états étant également sensibles aux interactions de Coulomb, une extension au cas multi-électronique des outils utilisés pour traiter ces interactions est proposée dans cette thèse. / Over the last few years, extensive experimental efforts have been devoted to thedevelopment of quantum nanoelectronics tools aiming at controlling electronic trans-port down to the single electron level. These advances led to a paradigm shift inthe domain of coherent electronic transport, giving birth to electron quantum optics,which is the domain of this work.This manuscript is devoted to two problems. The first of these is the one ofCoulomb interactions between electrons, which lead to a decoherence phenomenonthat must be characterized and predicted in order to be controlled. Using an analyt-ical and numerical approach, it became possible to predict the effect of interactionson an experimentally relevant system, a prediction that was then confirmed in the ex-periment. After this result, this manuscript displays some ideas aiming at controllinginteractions and proposes some ways to test them experimentally.In this work, I also took on the problem of characterizing complex quantum states.In particular, following the experimental demonstration of a tomography protocol forfirst order coherences, I tried to extend this protocol to more complex states thatcould exhibit two-electron coherences, or more. These states being also sensitive to Coulomb interactions, an extension of the tools used to treat interactions to thismulti-electronic state is also presented in this work.

Les problèmes de diffusion de particules, à deux et à trois corps, ont une importance cruciale en physique atomique, car ils servent à décrire différents processus de collisions. Actuellement, le cas de deux corps peut être résolu avec une précision numérique désirée. Les problèmes de diffusion à trois particules chargées sont connus pour être bien plus difficiles mais une déclaration similaire peut être affirmée. L’objectif de ce travail est de contribuer, d’un point de vue analytique, à la compréhension des processus de diffusion Coulombiens à trois corps. Ceci a non seulement un intérêt fondamental, mais est également utile pour mieux maîtriser les approches numériques en cours d’élaboration au sein de la communauté de collisions atomiques. Pour atteindre cet objectif, nous proposons d’approcher la solution du problème avec des développements en séries sur des ensembles de fonctions appropriées et possédant une expression analytique. Nous avons ainsi développé un nombre d’outils mathématiques faisant intervenir des fonctions Coulombiennes, des équations différentielles de second ordre homogènes et non-homogènes, et des fonctions hypergéométriques à une et à deux variables / Two and three-body scattering problems are of crucial relevance in atomic physics as they allow to describe different atomic collision processes. Nowadays, the two-body cases can be solved with any degree of numerical accuracy. Scattering problem involving three charged particles are notoriously difficult but something similar -- though to a lesser extent -- can be stated. The aim of this work is to contribute to the understanding of three-body Coulomb scattering problems from an analytical point of view. This is not only of fundamental interest, it is also useful to better master numerical approaches that are being developed within the collision community. To achieve this aim we propose to approximate scattering solutions with expansions on sets of appropriate functions having closed form. In so doing, we develop a number of related mathematical tools involving Coulomb functions, homogeneous and non-homogeneous second order differential equations, and hypergeometric functions in one and two variables

Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-08-23T13:35:50Z No. of bitstreams: 1 DANIEL BESERRA COSTA - DISSERTAÇÃO (PPGECA) 2018.pdf: 3178699 bytes, checksum: cdb4fe8ec72383894c5c447ebe2853ae (MD5) / Made available in DSpace on 2018-08-23T13:35:50Z (GMT). No. of bitstreams: 1 DANIEL BESERRA COSTA - DISSERTAÇÃO (PPGECA) 2018.pdf: 3178699 bytes, checksum: cdb4fe8ec72383894c5c447ebe2853ae (MD5) Previous issue date: 2018-02-21 / Capes / A deformação permanente é definida como o acúmulo de pequenas quantidades de deformação não recuperáveis resultante da aplicação das cargas dos veículos. A deformação permanente na camada de revestimento asfáltico pode ser oriunda por três mecanismos: deformação permanente por densificação, por uso e por fluência da mistura. Dado que as temperaturas de serviço da camada de revestimento estão em torno de 40 a 60 °C, a mistura asfáltica nesse intervalo de temperatura se comporta como um material sólido. Sendo assim, é razoável supor que os mecanismos de falha aplicáveis aos materiais sólidos sejam válidos para as misturas de asfálticas. Sendo o critério Mohr-Coulomb amplamente utilizado para descrever as características de cisalhamento de materiais sólidos, poderá ser utilizado para obtenção do ângulo de atrito interno da mistura, bem como o seu intercepto coesivo. Este trabalho teve como objetivo a determinação de ângulos de atrito internos de diferentes misturas asfálticas e sua influência no comportamento mecânico, em especifico, na resistência à deformação permanente destas misturas. Como forma de atingir o objetivo da pesquisa foi desenvolvido um programa experimental visando à avaliação das propriedades mecânicas relacionadas ao ângulo de atrito interno das misturas asfálticas com CAP 50/70 e E – 55/75. Foi possível executar análises em laboratório a partir da determinação de parâmetros de ruptura por cisalhamento, com o auxílio da teoria de Mohr-Coulomb, tendo como inferência o desempenho de misturas estudadas em campo. Verificou-se que, a cada acréscimo de 5% de partículas graúdas em uma faixa granulométrica, as misturas estudadas apresentaram, em geral, um ganho de 1° (Grau) no ângulo de atrito interno para cada faixa estudada. Entretanto, deve ser observado o limite de 30 a 35% de partículas graúdas para cada mistura. Pode-se concluir que: os parâmetros de ruptura por cisalhamento, ângulo de atrito interno e intercepto coesivo são fatores determinantes no desempenho a deformação permanente de misturas asfálticas. Para os ligantes utilizados os resultados indicaram que o acréscimo do ângulo de atrito interno resulta numa maior resistência a deformação permanente. / Permanent deformation is defined as the accumulation of small amounts of non-recoverable deformation resulting from the application of vehicle loads. The permanent deformation in the surface layer of asphalt pavements can come from three mechanisms: permanent deformation by densification, by use and by creep of the mixture. Since the service temperatures of the pavement surface layer are around 40 and 60 ºC, the asphalt mixture, in this temperature range, behaves as a solid material. Therefore, it is reasonable to assume that failure mechanisms applicable to solid materials are valid for asphalt mixtures. As the Mohr-Coulomb criterion is widely used to describe the shear characteristics of solid materials, it can be used to obtain the internal friction angle of the asphalt mixture as well as to estimate its cohesive intercept. This work had as objective to determine the internal angles of friction of different asphalt mixtures and their influence on the mechanical behavior, in particular, on the resistance to permanent deformation of these mixtures. In order to achieve the objective of this research, an experimental program was developed to evaluate the mechanical properties related to the internal angle of friction of asphalt mixtures with the 50/70 asphalt binder and the E 55/75 asphalt binder. It was possible to perform laboratory analyses from the determination of shear rupture parameters, supported by the Mohr-Coulomb's theory, inferred by the performance of mixtures studied in the field. It was verified that, at each increment of 5% of coarse particles in a particle size range, the studied mixtures presented, in general, a gain of 1° (degree) in the internal angle of friction for each size range studied. However, the limit of 30 to 35% of coarse particles should be observed for each mixture. It can be concluded that: the parameters of shear rupture, internal angle of friction and cohesive intercept are determining factors in the permanent deformation performance of asphalt mixtures. For the asphalt binders used, the results indicated that the increment of the internal angle of friction results in a greater resistance to permanent deformation.

xvi, 116 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / This dissertation focuses on low-dimensional electron transport phenomena in devices ranging from semiconductor electron 'billiards' to semimetal atomic clusters to gold nanoparticles. In each material system, the goal of this research is to understand how carrier transport occurs when many elements act in concert. In the semiconductor electron billiards, magnetoconductance fluctuations, the result of electron quantum interference within the device, are used as a probe of electron transport through arrays of one, two, and three connected billiards. By combining two established analysis techniques, this research demonstrates a novel method for determining the quantum energy level spacing in each of the arrays. That information in turn shows the extent (and limits) of the phase-coherent electron wavefunction in each of the devices. The use of the following two material systems, the semimetal atomic clusters and the gold nanoparticles, is inspired by the electron billiard results. First, the output of the simple, rectangular electron billiards, the magnetoconductance fluctuations, is quite generally found to be fractal. This research addresses the question of what output one might expect from a device with manifestly fractal geometry by simulating the electrical response of fractal resistor networks and by outlining a method to implement such devices in fractal aggregates of semimetal atomic clusters. Second, in gold nanoparticle arrays, the number of array elements can increase by orders of magnitude over the billiard arrays, all with the potential to stay in a similar, phase-coherent transport regime. The last portion of this dissertation details the fabrication of these nanoparticle-based devices and their electrical characteristics, which exhibit strong evidence for electron transport in the Coulomb-blockade regime. A sketch for further 'off-blockade' experiments to realize magnetoconductance fluctuations, i.e. phase-coherent electron phenomena, is presented. / Committee in charge: Jens Noeckel, Chairperson, Physics; Richard Taylor, Member, Physics; Heiner Linke, Member, Physics; David Strom, Member, Physics; James Hutchison, Outside Member, Chemistry

Made available in DSpace on 2016-06-02T20:15:20Z (GMT). No. of bitstreams: 1 2679.pdf: 25013011 bytes, checksum: c8fa361775e24d238927a782402fff59 (MD5) Previous issue date: 2009-10-16 / Universidade Federal de Sao Carlos / In this thesis we studied the quantum effects in networks of Josephson junctions under the induction of vortices and as a consequence of the size of the sample itself. For this, it also was carried out all the instrumentation required to achieve that goal. The superconducting devices known as Josephson junctions offer the opportunity to study a wide variety of concepts of basic physics, especially when they are in the form of twodimensional arrays called networks. In particular, these structures allow us to study quantum phenomena such as tunneling Josephson dc / ac, proximity effect, Coulomb blockade, quantum fluctuations and others like phase transition of Berezinsky-Kosterlitz-Thouless (BKT), all present in these devices. In particular, in this thesis we study two-dimensional networks of Josephson junctions of types SNS (superconductor-normal-superconductor) and SIS (superconductor-insulatorsuperconductor) with composition Nb -CuxAlyOz-Nb. The study of these samples was performed by obtaining the characteristic curves V × I with and without applied magnetic field. The analysis of these curves was performed by the law of power scale: ��������������for the SNS network, and ������������������/�������� for the SIS networks. The fact th��at ��t��w��o types of formulas adjustment is due to the asymptotic behavior present in these samples. Moreover, the temperature of the BKT transition was determined for ��������������������3. The analysis of the experimental obtained results clearly shows the dependence of quantum effects on the size of the samples studied. / Neste trabalho de Tese foram estudados os efeitos quânticos em redes de junções Josephson decorrentes da indução de vórtices e como conseqüência do tamanho da própria amostra. Para isso, também fora desenvolvida toda a instrumentação associada necessária para alcançar esse objetivo. Os dispositivos supercondutores conhecidos como junções Josephson oferecem a oportunidade de estudar uma ampla variedade de conceitos de física básica, principalmente quando eles se encontram na forma de arranjos bidimensionais denominados de redes. Em particular, estas estruturas permitem estudar fenômenos quânticos tais como tunelamento Josephson dc/ac, efeito de proximidade, bloqueio de Coulomb, flutuações quânticas e outras como a transição de fase de Berezinsky-Kosterlitz-Thouless (BKT), todos eles presentes nestes dispositivos. Em particular, nesta Tese estudamos redes de junções Josephson bidimensionais dos tipos SNS (supercondutor-normal-supercondutor) e SIS (supercondutor-isolante-supercondutor) com composição Nb-CuxAlyOz-Nb. O estudo dessas amostras foi realizado através da obtenção das curvas características V×I com e sem campo magnético aplicado. A análise dessas curvas foi realizada mediante a lei de escalas de potencias: ������������������������ para as redes SNS, e ������������������/�������� para as redes SIS. O fato de ter dois tipos de fórmulas de ajuste é devido ao comportamento assintótico presente nessas amostras. Além disso, a temperatura de transição de BKT foi determinada para ��������������������3. A análise dos resultados experimentais obtidos mostra claramente a dependência desses efeitos quânticos com o tamanho das amostras estudadas.