The Large Eddy Simulation approach is employed to predict the flow physics and heat transfer characteristics of a film-cooling problem that is formed from the interaction of a coolant jet with a hot mainstream flow. The film-cooling technique is used to protect turbine blades from thermal failure, allowing the gas inlet temperature to be increased beyond the failure temperature of the turbine blade material in order to enhance the efficiency of gas turbine engines. A coolant fluid is injected into the hot mainstream through several rows of injection holes placed on the surface of a gas turbine blade in order to form a protective coolant film layer on the blade surface. However, due to the complex, unsteady and three-dimensional interactions between the coolant and the hot gases, it is difficult to achieve the desired cooling performance. Understanding of this complex flow and heat transfer process will be helpful in designing more efficiently cooled rotor blades. A comprehensive numerical investigation of a rotating film-cooling performance under different conditions is conducted in this thesis, including film-cooling on a flat surface and film-cooling on a rotating gas turbine blade. The flow-governing equations are discretised based on the finite-volumes method and then solved iteratively using the well-known SIMPLE and PISO algorithms. An in-house FORTRAN code has been developed to investigate the flat plate film-cooling configuration, while the gas turbine blade geometry has been simulated using the STAR-CCM+ CFD commercial code. The first goal of the present thesis is to investigate the physics of the flow and heat transfer, which occurs during film-cooling from a standard film hole configuration. Film-cooling performance is analysed by looking at the distribution of flow and thermal fields downstream of the film holes. The predicted mean velocity profiles and spanwise-averaged film-cooling effectiveness are compared with experimental data in order to validate the reliability of the LES technique. Comparison of adiabatic film-cooling effectiveness with experiments shows excellent agreement for the local and spanwise-averaged film-cooling effectiveness, confirming the correct prediction of the film-cooling behaviour. The film coverage and film-cooling effectiveness distributions are presented along with discussions of the influence of blowing ratio and rotation number. Overall, it was found that both rotation number and blowing ratio play significant roles in determining the film-cooling effectiveness distributions. The second goal is to investigate the impact of innovative anti-vortex holes on the film-cooling performance. The anti-vortex hole design counteracts the detrimental kidney vorticity associated with the main hole, allowing coolant to remain attached to the blade surface. Thus, the new design significantly improves the film-cooling performance compared to the standard hole arrangement, particularly at high blowing ratios. The anti-vortex hole technique is unique in that it requires only readily machinable round holes, unlike shaped film-cooling holes and other advanced concepts. The effects of blowing ratio and the positions of the anti-vortex side holes on the physics of the hot mainstream-coolant interaction in a film-cooled turbine blade are also investigated. The results also indicate that the side holes of the anti-vortex design promote the interaction between the vortical structures; therefore, the film coverage contours reveal an improvement in the lateral spreading of the coolant jet.

Le travail exposé dans cette thèse de doctorat présente des expériences à basse température dans le domaine de la spintronique quantique sur des hétérostructures à base de germanium. Tout d’abord, les avantages attendus du germaniumpour la spintronique quantique sont exposés, en particulier la faible interaction hyperfine et le fort couplage spin-orbite théoriquement prédits dans le Ge. Dans un second chapitre, la théorie des boites quantiques et systèmes à double boite sont détaillés, en se focalisant sur les concepts nécessaires à la compréhension des expériences décrites plus tard, c’est-à-dire les effets de charge dans les boites quantiques et double boites, ainsi que le blocage de spin de Pauli. Le troisième chapitre s’intéresse à l’interaction spin-orbite. Son origine ainsi que ses effets sur les diagrammes d’énergie de bande sont discutés. Ce chapitre se concentre ensuite sur les conséquences de l’interaction spin-orbite spécifiques aux gaz bidimensionnels de trous dans des hétérostructures de germanium, c’est-à-dire l’interaction spin-orbite Rashba, le mécanisme de relaxation de spin D’Yakonov-Perel ainsi que l’antilocalisation faible.Le chapitre quatre présente des mesures effectuées sur des nanofils coeur coquillede Ge/Si. Dans ces nanofils une boite quantique se forme naturellement et celui-ci est étudié. Un système à double boite quantiques est ensuite formé par utilisation de grilles électrostatiques, révélant ainsi du blocage de spin de Pauli.Dans le cinquième chapitre sont détaillés des mesures demagneto-conductance de gas de trous bidimensionnels dans des hétérostructures de Ge/SiGe contraints dont le puit quantique se situe à la surface. Ces mesuresmontrent de l’antilocalisation faible. Les temps de transport caractéristiques sont extraits ainsi que l’énergie de séparation des trous 2D par ajustement de courbe de la correction à la conductivité due à l’antilocalisation. De plus, les mesures montrent une suppression de l’antilocalisation par un champ magnétique parallèle au puit quantique. Cet effet est attribué à la rugosité de surface ainsi qu’à l’occupation virtuelle de sous-bandes inoccupées.Finalement, le chapitre six présente des mesures de quantisation de la conductancedans des hétérostructures de Ge/SiGe contraints dont le puit quantique est enterré. Tout d’abord, l’hétérostructure est caractérisée grâce à des mesures de magneto-conductance dans une barre de Hall. Ensuite, un second échantillon dessiné spécialement pour la réalisation de points de contact quantiques est mesuré. Celui-ci montre des marches de conductance. La dépendance en champ magnétique de ces marches est mesurée, permettant ainsi une extraction du facteur gyromagnétique de trous lourds dans du germanium. / This thesis focuses on low temperature experiments in germaniumbased heterostructure in the scope of quantumspintronic. First, theoretical advantages of Ge for quantum spintronic are detailed, specifically the low hyperfine interaction and strong spin orbit coupling expected in Ge. In a second chapter, the theory behind quantum dots and double dots systems is explained, focusing on the aspects necessary to understand the experiments described thereafter, that is to say charging effects in quantum dots and double dots and Pauli spin blockade. The third chapter focuses on spin orbit interaction. Its origin and its effect on energy band diagrams are detailed. This chapter then focuses on consequences of the spin orbit interaction specific to two dimensional germaniumheterostructure, that is to say Rashba spin orbit interaction, D’Yakonov Perel spin relaxation mechanism and weak antilocalization.In the fourth chapter are depicted experiments in Ge/Si core shell nanowires. In these nanowire, a quantumdot formnaturally due to contact Schottky barriers and is studied. By the use of electrostatic gates, a double dot system is formed and Pauli spin blockade is revealed.The fifth chapter reports magneto-transport measurements of a two-dimensional holegas in a strained Ge/SiGe heterostructure with the quantum well laying at the surface, revealing weak antilocalization. By fitting quantumcorrection to magneto-conductivity characteristic transport times and spin splitting energy of 2D holes are extracted. Additionally, suppression of weak antilocalization by amagnetic field parallel to the quantum well is reported and this effect is attributed to surface roughness and virtual occupation of unoccupied subbands.Finally, chapter number six reportsmeasurements of quantization of conductance in strained Ge/SiGe heterostructure with a buried quantumwell. First the heterostructure is characterized by means ofmagneto-conductance measurements in a Hall bar device. Then another device engineered specifically as a quantum point contact is measured and displays steps of conductance. Magnetic field dependance of these steps is measured and an estimation of the g-factor for heavy holes in germanium is extracted.

Black hole spin is an essential parameter, for it provides us with the infor- mation on the black hole formation and growth. In this Thesis, we simulated observations for an upcoming X-ray polarimetric mission IXPE (Imaging X- ray Polarimetry Explorer) with the aim to study the robustness of black hole spin and inclination measured via X-ray polarimetry. To simulate polarization spectra, we used a multicolor blackbody emission model accounting for thermal radiation from the accretion disk. For the case of maximally rotating black hole (spin a = 0.998), we were able to reconstruct both spin and inclination of the system with a high precision (∆a ≤ 0.2 for spin and ∆θ ≤ 15 deg for inclination). For less rotating black holes, the spin was correctly recovered, but with a large uncertainty. The inclination is well constrained for any spin value. We conclude that polarimetric measurements will be useful to make independent black hole spin measurements, that would be compared with the spectral-fitting and timing methods. Therefore, X-ray polarimetric missions will be highly desirable. 1

Na Planície Costeira Sul de Santa Catarina, entre o rio Mampituba e o norte da lagoa do Sombrio encontram-se depósitos costeiros gerados por transgressões e regressões da linha de costa durante o Quaternário. A área de estudo situa-se em um suave embaiamento costeiro onde a barreira holocênica apresenta um comportamento progradacional. Contudo, dados de subsuperfície adquiridos através do método geofísico do GPR na porção mais interna deste setor, revelaram a presença de refletores inclinados no sentido do continente, evidenciando a fase retrogradacional da barreira holocênica. Estes refletores são interpretados como estratos sedimentares formados em ambiente subaquoso, correspondente à margem lagunar que progradou no sentido do continente. A inversão dos refletores no sentido do oceano corresponde à fase progradacional, sendo estes interpretados como estratos formados no pós-praia (backshore) e na zona de estirâncio (foreshore). As diferentes fácies reconhecidas em subsuperficie com o GPR foram caracterizadas com o auxilio de dois furos de sondagens SPT (Standard Penetration Test). Os dados obtidos nos testemunhos permitiram diferenciar aspectos como textura, cor, conteúdo fossilífero, teor de matéria orgânica e forma dos grãos. Os depósitos sedimentares relacionados à fase retrogradacional são representados por areias finas a muito finas, com a presença de até 34% de lama. Por outro lado, os depósitos relacionados à fase progradacional são compostos por areias finas sem contribuição significativa de lama. Por fim, a datação por radiocarbono de um fragmento de madeira, localizado na fácies interpretada como a margem lagunar, revelou que esta foi depositada há cerca de 8 ka AP, em um nível relativo do mar aproximadamente 7 m abaixo do atual. Esta margem, que progradou no sentido do continente, corresponde à fase retrogradacional (transgressiva) da barreira holocênica. / In the Southern Santa Catarina Coastal Plain, between Mampituba river and the northern Sombrio lagoon, are present coastal deposits generated by shoreline transgressions and regressions during the Quaternary. The study area is situated on a gentle coastal embayment where the holocenic barrier has a progradational behavior. However, subsurface data acquired through the GPR in the innermost portion of this sector, revealed the presence of reflectors inclined landward, evidencing the retrogradational phase of the holocenic barrier. These reflectors are interpreted as sedimentary strata formed in subaqueous environment, corresponding to the margin lagoon which prograded landward. The reversal of reflectors basinward corresponds to the progradational phase, which is interpreted as backshore and foreshore strata. The facies recognized in subsurface with GPR were characterized with the aid of two SPT (Standard Penetration Test) drill holes. The core data allowed differentiate aspects such as texture, color, grain shape, fossil and organic matter content. Sedimentary deposits related to the retrogradational phase are represented by fine to very fine sand, with the presence of until 34% of mud. On the other hand, progradational deposits are composed of fine sand without significant mud content. Finally, the radiocarbon dating of a wood fragment, located in lagoon margin facies, showed that it was deposited at about 8 ka BP, in a mean sea level of around 7 m below the current level. This margin, which prograded landwards, corresponds to the retrogradational phase of the holocenic barrier (transgressive).

We firstly numerically recalculate the Ricci tensor of non-stationary axisymmetric space-times (originally calculated by Chandrasekhar) and we find some discrepancies both in the linear and non-linear terms. However, these discrepancies do not affect the results concerning linear perturbations of a Schwarzschild black hole. Secondly, we use these Ricci tensors to derive the Zerilli and Regge-Wheeler equations and use the Newman-Penrose formalism to derive the Bardeen-Press equation. We show the relation between these equations because they describe the same linear perturbations of a Schwarzschild black hole. Thirdly, we illustrate heuristically (when the angular momentum (l) is 2) the relation between the linearized solution of the Einstein vacuum equations obtained from the Bondi-Sachs metric and the Zerilli equation, because they describe the same linear perturbations of a Schwarzschild black hole. Lastly, by means of a coordinate transformation, we extend Chandrasekhar's results on linear perturbations of a Schwarzschild black hole to the Bondi-Sachs framework. / Mathematical Sciences / M. Sc. (Applied Mathematics)

xv, 177 p. : ill. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / In this dissertation, three different topics related to terascale physics are explored. First, a new method is suggested to match next-to-leading order (NLO) scattering matrix elements with parton showers. This method is based on the original approach which adds primary parton splittings in Born-level Feynman graphs in order to remove several types of infrared divergent subtractions from the NLO calculation. The original splitting functions are modified so that parton showering has a less severe effect on the jet structure of the generated events. We also examine the Large Hadron Collider phenomenology of quantum black holes in models of TeV scale gravity. Based on a few minimal assumptions, such as the conservation of color charges, interesting signatures are identified that should be readily visible above the Standard Model background. The detailed phenomenology depends heavily on whether one requires a Lorentz invariant, low-energy effective field theory description of black hole processes. Finally, in the calculation of cross sections in high energy collisions at NLO, one option is to perform all of the integrations, including the virtual loop integration, by Monte Carlo numerical integration. A new method is developed to perform the loop integration directly, without introducing Feynman parameters, after suitably deforming the integration contour. Our example is the N-photon scattering amplitude with a massless electron loop. Results for six photons and eight photons are reported. / Committee in charge: Stephen Hsu, Chairperson, Physics; Graham Kribs, Member, Physics; David Strom, Member, Physics; Davison Soper, Member, Physics; Marina Guenza, Outside Member, Chemistry

A search for quantum black holes with color charge decaying to one electron and one quark has been performed using data collected by the ATLAS Experiment at the Large Hadron Collider corresponding to 2.29 fb−1. No excess over the expected Standard Model interactions has been observed. Limits are set on the production cross section for events with one electron and one jet resulting from new physical phenomena. Models with a combined invariant mass of the electron and jet larger than or equal to 2.5TeV and a cross section above 2.6 fb are excluded at the 95% confidence level. This allows the exclusion of a significant part of the parameter space of quantum black hole models.

SILVA, Carlos Alex Souza da. Espaços Fuzzy e aspectos quânticos dos buracos negros. 2011. 90 f. Tese (Doutorado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2011. / Submitted by Edvander Pires (edvanderpires@gmail.com) on 2015-05-19T18:59:25Z No. of bitstreams: 1 2011_tese_cassilva.pdf: 1020582 bytes, checksum: 1b31f01769f35ca43fcda25a0b345393 (MD5) / Approved for entry into archive by Edvander Pires(edvanderpires@gmail.com) on 2015-05-22T20:03:22Z (GMT) No. of bitstreams: 1 2011_tese_cassilva.pdf: 1020582 bytes, checksum: 1b31f01769f35ca43fcda25a0b345393 (MD5) / Made available in DSpace on 2015-05-22T20:03:22Z (GMT). No. of bitstreams: 1 2011_tese_cassilva.pdf: 1020582 bytes, checksum: 1b31f01769f35ca43fcda25a0b345393 (MD5) Previous issue date: 2011 / A model based on the topology change of a quantum manifold is used to explain the origin of the black hole thermodynamics. Some important issues are addressed, for example, why black holes obey a generalized second law of thermodynamics. The method we use to do this is to analyze the selection rules for black hole area transitions in the evaporation process driven by topology change. A discrete spectrum, which becomes increasingly spaced as the black hole approaches the Planck scale, is obtained for the black hole area. The black hole information loss paradox is also addressed. / Propomos um modelo baseado na mudança de topologia de uma variedade quântica no sentido de justificar a origem da termodinâmica dos buracos negros. Alguns pontos importantes são discutidos, por exemplo, o porquê de os buracos negros obedecerem a uma segunda lei generalizada da termodinâmica. Para isso, nós estudamos as regras de seleção que governam as transições de área de um buraco negro durante o seu processo de evaporação, sendo estas governadas pelo processo de mudança de topologia. Obtemos um espectro discreto para a área do horizonte de eventos, o qual se torna cada vez mais espaçado à medida que o buraco negro aproxima da escala de Planck. O paradoxo da perda de informação por buracos negros é, também, discutido.

Made available in DSpace on 2014-06-11T19:25:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-11-10Bitstream added on 2014-06-13T18:28:53Z : No. of bitstreams: 1 ried_k_me_ift.pdf: 945643 bytes, checksum: 96fe05a885b68fc97682e8238f4ecf2c (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / When seeking inspiration for a future theory of quantum gravity, studying black holes is a promising ansatz, since they present us with several puzzles at the intersection of quantum theory and gravity. Among these is their entropy: although there are compelling arguments for its existence, its origin and statistical meaning remain a mystery. Previous work showed that at least some aspects of this phenomenon can be accounted for by the entanglement of quantum fields across the horizon: if a field is globally in a pure state, yet part of it is hidden behind the event horizon, then the reduced state of the remainder possesses non-zero entropy. This is the possibility we explore in the present work, in the simplest of settings: a ground-state escalar field, defined in three-dimensional, flat or unifromily curved space, and derive an expression for the entropy, which is evauated numerically. the results show that the entropy scales with the boundary area of the inaccessible region, a key feature of black hole entropy known as the area law. Furthermore. we conclude that the dominant contribution to the entropy is due to short-range interactions, and discuss some physical implications of this insight for the puzzle of black hole entropy

Made available in DSpace on 2014-06-11T19:32:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-28Bitstream added on 2014-06-13T18:43:08Z : No. of bitstreams: 1 landulfo_ags_dr_ift.pdf: 1384269 bytes, checksum: 63c70f6df185aec50583b1cc399bbf1b (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Mesmo tratando a gravidade classicamente, a Teoria Quântica de Campos em Espaços Tempos Curvos (TQCEC) faz previsões impressionantes sobre o comportamento de campos quânticos na presença de campos gravitacionais. Entretanto, ao mesmo tempo em que nos revela efeitos surpreendentes, a TQCEC levanta uma série de questionamentos. O desenvolvimento de uma teoria na interface entre a teoria da relatividade, a mecânica quântica e a teoria da informação poderá não só lançar uma nova luz em tais questões como também nos permitir descobrir novos efeitos de gravitação quântica de baixas energias. Entretanto, os efeitos que a teoria da relatividade causa na teoria da informação quântica são não triviais já no espaço-tempo de Minkowski. Faz-se necessáaria portanto uma análise cuidadosa de tais efeitos já no contexto da relatividade especial. Sendo assim, estudamos primeiro o comportamento das desigualdades de Bell usando férmions de spin 1/2 e fótons quando os detetores que medem spin e polarização, respectivamente, movemse com certa velocidade. Além disso, usamos o limite de Holevo para estudar sistemas de comunicação quando as partes que trocam informação tem um movimento relativo. Como um desenvolvimento natural, estudamos diversos aspectos da teoria da informação quântica no contexto da teoria quântica de campos e, em particular, do efeito Unruh. Tais resultados nos permitiram prever o comportamento de qubits nas vizinhanças de um buraco negro de Schwarzschild / Although it treats gravity classically, the Quantum Field Theory in Curved Spacetimes (QFTCS) makes remarkable predictions about de behavior of quantum fields in the presence of gravitational fields. However, these striking discoveries raises several issues. The development of a theory at the interface between the theory of relativity, quantum mechanics and information theory could not only shed new light on such questions as well as allow us to uncover new low-energy quantum gravity effects. However, relativity affects quantum information theory in a highly non-trivial way already in Minkowski spacetime. Therefore, a careful analysis of these effects in the context of special relativity is needed. For this purpose, we begin investigating how the movement of the spin and polarization detectors influences the Bell inequalities using spin 1/2 fermions and photons, respectively. Then, we use the Holevo bound to investigate quantum communication channels when the parts that trade information have a relative motion. As a natural development, we use quantum field theory and, in particular, the Unruh effect to analyze several aspects of quantum information theory. This enables us to predict the behavior of qubits in the vicinity of a Schwarzschild black hole