Este trabalho tem como objetivo principal direcionar a tomada de decisões para a escolha dos diferentes parâmetros que envolvem o alinhamento horizontal e vertical do projeto geométrico ferroviário de trens de alta velocidade (TAV) e de longo percurso, bem como descrever conceitos teóricos para parâmetros de segurança e conforto, baseados em normas internacionais. A pesquisa se desenvolve através de consultas em revistas especializadas, artigos, publicações, normas técnicas e livros. Pela escassez de dados em língua nacional e material bibliográfico desatualizado, as pesquisas se concentram essencialmente em material internacional. Apesar do Brasil ser um dos países em desenvolvimento com maior ascensão no cenário global, tem apresentado, nas últimas décadas, sérios problemas de infra-estrutura devido a uma distribuição desequilibrada na área de transportes, com altíssima concentração no modo rodoviário, com aeroportos e rodovias operando acima da capacidade satisfatória, além de um leque limitado de alternativas de transporte. Devido à falta de investimentos no setor ferroviário, grande parte da malha ferroviária brasileira tornou-se inoperante ou até mesmo inexistente, resultando numa enorme diminuição da mão de obra qualificada e formação acadêmica nesse ramo. Como conseqüência, os estudos relacionados ao projeto ferroviário também foram afetados diretamente. Nesse contexto, é importante que se resgate normas, publicações, especificações técnicas e experiências adotadas em outros países com sólidas tradições ferroviárias, de modo a incorporar em nossa formação acadêmica tais conceitos, como é um dos objetivos dessa dissertação. / This dissertation has as main objective to guide in taking decisions for the selection of different parameters which involve the horizontal and vertical railway geometric design of high speed (HST) and long distance trains as well as theoretical concepts for describing security parameters and comfort, based on international standards. The research is developed through consultations in specialized magazines, articles, publications, standards and technical books. Due to the scarcity of data in the national language and outdated library materials, the research focuses primarily on international material. Although Brazil is a developing country with one of the highest rises in the global scene, the country has faced in recent decades serious infrastructure problems due to an uneven distribution in the area of transport, with high concentration in the road, and airports and roads operating above satisfactory capacity, resulted by a limited range of transportation alternatives. Due to the lack of investment in the railway sector, much of the Brazilian railway system became inoperative or even nonexistent, resulting in a tremendous decrease of skilled labor and academic training in this field. As a result, studies related to the railway project have also been directly impacted. In this context, it is important to rescue standards, publications, experiences and technical specifications adopted in other countries with strong tradition in railways in order to incorporate these concepts into our academic formation, which is one of the purposes of this dissertation.

Este trabalho caracterizou os siltitos do Grupo Itararé, rocha branda proveniente da amostragem de pedreira localizada nas proximidades de futuro empreendimento brasileiro, o Trem de Alta Velocidade. Objetivou entender as causas da pronunciada e rápida alteração da rocha intacta, e simular, em condições controladas de laboratório, a degradação hidromecânica causada pela simples variação da umidade relativa do ar. Para tal, estabeleceu-se técnica de amostragem de testemunhos por meio da extração via seca com ar-comprimido, e processo de intemperismo artificial, composto por 4 ciclos de 2 etapas (secagem e umedecimento). O processo se deu em dessecadores, sendo a variação da umidade ocasionada pela técnica do vapor e sílica gel. O acompanhamento da degradação dos corpos de prova efetuou-se com duas técnicas não-destrutivas de propagação de ondas: o pulso ultrassônico e a excitação por impulso (sistema Sonelastic). Em paralelo, realizou-se a caracterização geotécnica dos siltitos em umidade natural, com ensaios mineralógicos, físicos, físico-mecânicos, físico-químicos e de alteração laboratorial. Por meio desta metodologia, foi possível estimar as minorações do módulo de deformabilidade e da resistência, além das causas físico-químicas da degradação. / This work characterized the siltstones of the Itararé Group, a soft rock sampled in a quarry located near a future Brazilian venture, the High Speed Train. It aims at understanding the causes of the pronounced and fast changes of the intact rock, and simulate in controlled laboratory conditions the hydro degradation process caused by simple variation of relative air humidity. Dry sampling technique with compressed air was used to extract samples from blocks, and the process of artificial weathering consisted on 4 cycles of 2 steps (drying and wetting). The process occurred in desiccators, where moisture variation was caused by the vapor technique and silica gel. The monitoring of the specimens degradation was performed with two non-destructive wave propagation techniques: the ultrasonic pulse and the impulse excitation (Sonelastic system). A geotechnical characterization of the siltstones in natural moisture condition was made in parallel, consisting on mineralogical, physical, physical-mechanical, physical-chemical and durability tests. By this methodology, it was possible to estimate the mitigation of the deformability modulus and strength besides the physical- chemical causes of degradation.

The interaction of a shock wave and boundary layer often occurs in high speed flows. For sufficiently strong shock strengths the boundary layer separates, generating shock patterns in the contiguous inviscid flow (termed strong interactions); which may also affect the performances of the systems where they occur, demanding control of the interaction to enhance the performances. The case of impinging shock wave boundary layer interaction is of fundamental importance and can throw light on the physics of the interaction in general. Although various aspects of the interaction are studied at supersonic speeds, the complexities involved in the interaction at hypersonic speeds are not well understood. Of importance is the high total enthalpy associated with hypersonic flows the simulation of which requires shock tunnels. The present experimental study focuses on the interaction between strong impinging shock and boundary layer in hypersonic flows of moderate to high total enthalpies. Experiments are performed in hypersonic shock tunnels HST-2 and FPST (free piston driven shock tunnel), at nominal Mach numbers 6 and 8, with total enthalpy ranging from 1.3 MJ/kg to 6 MJ/kg, and freestream Reynolds number ranging from 0.3 million/m to 4 million/m. The strong impinging shock is generated by a wedge of angle 30.960 to the freestream. The shock is made to impinge on a flat plate (made of Hylem which is adiabatic, except for one case with plate made of aluminium which allows heat transfer). The position of (inviscid) shock impingement may be varied (from 55 mm from the leading edge to 100 mm from the leading edge) by moving the plate back and forth on the fixture which holds the wedge and the plate. Expectedly the strong shock generates a large separation bubble of length comparable to the distance of the location of shock impingement from the leading edge of the plate. Such large separation bubbles are typical of supersonic/hypersonic intakes at off-design operation. The evolution of the flow field- including the evolution of impinging shock and subsequent evolution of the large separation bubble- within the short test duration of the shock tunnels is one of the main concerns addressed in the study. Time resolved schlieren flow visualizations using high speed camera, surface pressure measurements using PCB, kulite and MEMS sensors, surface convective heat transfer measurements using platinum thin film sensors are the flow diagnostics used. From the time resolved visualizations and surface pressure measurements with the fast response sensors, the flow field, even with a separation bubble as large as 75 mm (at Mach 5.96, with shock impingement at 95 mm from the leading edge) was found to be established within the short shock tunnel test time. The effects of various parameters- freestream Mach number, distance of the location of shock impingement, freestream total enthalpy and wall heat transfer- on the interaction are investigated. With increase in Mach number from 5.96 to 8.67, for nearly the same shock impingement locations (95 mm and 100 mm from the leading edge respectively), the separation length decreased from 75 mm to 60 mm despite the fact that the shocks are doubly stronger at the higher Mach number. Inflectional trend in separation length was observed with enthalpy at nominal Mach number 8- separation length increased from 60 mm at 1.6 MJ/kg to 70 mm at 2.4 MJ/kg, and decreased drastically to ~40 mm at 6 MJ/kg (when dissociations are expected). The separation length Lsep for all the experiments, except the experiments at 6 MJ/kg, were found to be large, i.e. comparable with the distance xi of location of shock impingement from the leading edge of the flat plate. The scaled separation length (with Hylem wall) was found to obey the inviscid similarity law proposed from the present study for large separation bubbles with strong impinging shocks, where M∞ is the freestream Mach number, p∞ is the freestream pressure and pr is the measured reattachment pressure; this holds for freestream total enthalpy ranging from 1.3 MJ/kg to 2.4 MJ/kg and Reynolds number (based on location of shock impingement) ranging from 1x105 to 4x105. While the increase in separation length from 1.6 MJ/kg to 2.4 MJ/kg could thus be attributed to the small difference in Mach number between the cases (due to inverse variation with cube of Mach number), the decrease in separation length and the non-confirmation to the proposed similarity law for the 6 MJ/kg case is attributed to the real gas effects. At Mach 6 the flow was observed to separate close to the leading edge, even when the (inviscid) shock impingement was at 95 mm from the leading edge. This prompted the proposal of an approximate inviscid model of the interaction for the Mach 6 case with separation at leading edge, and reattachment at the location of (inviscid) shock impingement; Accordingly, the closer the location of impingement, the more the angle that the separated shear layer makes with the plate and hence more the pressure inside the separation bubble. A small reduction in separation length was also observed with aluminium wall when compared with Hylem wall, emphasizing the importance of wall heat conductivity (especially when concerning separated flows) even within the short test durations of shock tunnels. The free interaction theory over adiabatic wall was found to predict the pressure at the location of separation, but under-predict the plateau pressure (at nominal Mach number 8). Numerical simulations (steady, planar) were also carried out using commercial CFD solver FLUENT to complement the experiments. Simulations using one equation turbulence model (Spalart-Allmaras model) were closer to the experimental results than the laminar simulations, suggesting that the flow field may be transitional or turbulent after separation. Significant reduction of the separation bubble length was demonstrated with the control of the interaction using boundary layer bleed within the short test time of the shock tunnel; with tangential blowing at the separation location20% reduction in separation length was observed, while with suction at separation location the reduction was 13.33 %.

Il y a près de trente ans, la première exoplanète a été détectée autour d'une étoile autre que le Soleil. Bien que plus de cinq mille exoplanètes aient été confirmées à ce jour, nous n’avons étudié l’atmosphère que de quelques dizaines d’entre elles et, dans la plupart des cas, n’avons eu accès qu’à une seule molécule. Nous commençons tout juste à découvrir la diversité des atmosphères exoplanétaires, et entrons dans une ère de caractérisation détaillée grâce à une nouvelle génération de télescopes, qui ouvre de nouvelles perspectives sur leur évolution et les processus chimiques et dynamiques qui les régissent. Au cours des dernières années, j'ai contribué à des études sur des exoplanètes allant de petites planètes de type terrestre jusqu’à des géantes gazeuses aux densités extrêmement faibles. Cette thèse contient quatre de ces études, qui exploitent une variété de méthodes d'observation et de modélisation. Dans le premier article, nous nous sommes penchés sur WASP-107 b, une planète de la taille de Jupiter avec une densité étonnamment faible, l'une de quelques énigmatiques ``super-puffs''. Nous avons obtenu une nouvelle mesure de la masse de cette planète en utilisant les données récoltées par une campagne de vitesses radiales sur quatre ans, ce qui était essentiel à l’étude de son atmosphère. Nous avons également détecté un compagnon planétaire lointain, WASP-107 c. Notre nouvelle mesure de la masse est encore plus faible que les estimations précédentes et, combinée aux contraintes existantes sur la composition de l'atmosphère obtenues à l'aide de spectroscopie de transmission, celle-ci semblait indiquer une masse très faible pour le noyau planétaire, remettant en question les modèles existants de formation des planètes géantes. Nous avons proposé de nouveaux scénarios dans lesquels de telles planètes géantes peuvent malgré tout accumuler leur envelope de gaz sur des noyaux de faible masse, à de grandes distances de leur étoile hôte. Dans la deuxième étude, nous nous sommes tournés vers un type de planète très différent avec Kepler-138 d, une petite planète de 1,5 rayons terrestres. Nous avons analysé les observations de transit obtenues avec les télescopes spatiaux Hubble et Spitzer et constaté que l'interaction gravitationnelle entre les trois planètes connues du système, Kepler-138 b, c et d, ne peut expliquer les variations des moments de transit de Kepler-138 d, nécessitant la présence d'une quatrième planète. Nous obtenons de nouvelles mesures des masses de Kepler-138 c et d, qui révèlent que leurs densités sont trop faibles pour être compatibles avec la composition rocheuse communément attendue pour des planètes de cette taille. En combinant la modélisation de la structure planétaire avec des calculs d'échappement atmosphérique, nous démontrons que ces planètes ont probablement des intérieurs supercritiques et des atmosphères composées d'eau ou d'autres espèces chimiques ayant une densité similairement élevée. La planète faisant l’objet de notre troisième étude, GJ 9827 d, mesure à peine 2 rayons terrestres. Comme Kepler-138 d, sa densité est intermédiaire entre les planètes plus grandes qui ont des enveloppes dominées par l'hydrogène, et les plus petites planètes rocheuses, ce qui suggère une composition atmosphérique potentiellement enrichie en métaux. Nous exploitons les observations de transit de l'atmosphère de GJ 9827 d avec JWST NIRISS/SOSS pour déterminer que sa composition atmosphérique est fortement enrichie en molécules au poids moléculaire élevé, y compris de grandes quantités d'eau, et est pauvre en hydrogène par rapport aux planètes légèrement plus grandes. Nous proposons des diagnostics observationnels pour déterminer l'origine de cet enrichissement en métaux, qui pourrait provenir de grandes quantités initiales de glaces accrétées, des interactions géochimiques entre l'atmosphère et l'océan de magma sous-jacent, ou de la perte progressive des constituants atmosphériques les plus légers au fil du temps. Le quatrième et dernier travail présenté dans cette thèse a pour objet une petite exoplanète rocheuse tempérée (température d’environ 12 degrés Celsius) et mesurant 0,8 rayon terrestre, TRAPPIST-1 d. Nous observons son spectre de transmission en utilisant JWST NIRSpec/PRISM, et ne détectons aucune signature atmosphérique planétaire, malgré notre haute sensibilité même aux atmosphères secondaires fines et de poids moléculaire élevé similaires aux planètes rocheuses du système solaire. Nous proposons que TRAPPIST-1 d a soit été dépouillée de son atmosphère par l'irradiation intense qu'elle reçoit de son étoile, soit qu'elle présente des signatures d'absorption très faibles en transmission, en raison d'une atmosphère de poids moléculaire élevé avec une pression de surface extrêmement faible, ou de la présence de nuages à haute altitude qui masquent les signatures d'une atmosphère plus profonde. Ces études ne représentent qu'un modeste sous-ensemble de la richesse des informations qui peuvent être obtenues sur la nature des exoplanètes et de leurs atmosphères grâce à des études observationnelles détaillées, soutenues par des approches de modélisation rigoureuses. De nouveaux télescopes tels que le JWST permettent maintenant la caractérisation atmosphérique de plus en plus précise d'un échantillon croissant d'exoplanètes. De telles observations nous permettront bientôt de construire un échantillon statistique d'atmosphères d'exoplanètes qui défiera sans aucun doute davantage nos modèles et hypothèses, et nous rapprochera de la compréhension des facteurs sous-jacents à leur diversité. / Exoplanet discoveries are closing in on the third decade since the first detection of a planet orbiting a star other than the Sun. While over five thousand exoplanets have been confirmed to date, only a few dozen of them have had their atmospheres studied, with, for most of them, constraints on only one molecular species. We are only now starting to uncover the diversity of exoplanet atmospheres, entering an era of detailed exoplanet atmosphere characterization and opening new windows into their evolution, chemistry, and dynamics. Over the past few years, I have contributed to studies of exoplanets ranging from small terrestrial worlds to the puffiest gas giants. This thesis contains four of these studies, which leverage a variety of observational methods and modeling perspectives. In the first work, we study WASP-107 b, a Jupiter-size planet with a stunningly low density, one of a few puzzling ``super-puffs''. We provide a new measurement of the planet's mass by leveraging a four-year radial-velocity campaign, which was essential to enable further atmosphere characterization. Our observations also enable us to detect a planetary companion, WASP-107c, on a wide orbit. Our new mass is even lower than previous estimates and, combined with the existing constraints on the atmosphere's metal content from transmission spectroscopy, seems to point to a very low core mass that challenges current models of giant planet formation. We propose a new channel of fast giant planet formation that would allow for such ``super-puffs'' to accrete their gas onto low-mass cores, at large distances from their host star. In the second study, we turn to a very different type of planet with Kepler-138 d, a small 1.5 Earth-radii planet, where we analyze transit observations obtained with the Hubble and Spitzer space telescopes. We find that the gravitational interaction between the three known planets in the system, Kepler-138 b, c, and d, cannot explain the variations in the transit times of Kepler-138 d, which require the presence of a fourth planet. We revise our estimates of the masses and compositions of Kepler-138 c and d, which reveal that their densities are too low to be compatible with the rocky compositions commonly assumed for planets in that size range. By combining planetary structure modeling with atmospheric escape calculations, we demonstrate that these planets are likely candidate ``water worlds'', with supercritical interiors and steam atmospheres. The third study focuses on a 2-Earth-radii planet, GJ 9827 d. Similarly to Kepler-138 d, GJ 9827 d has an intermediate density between larger planets with hydrogen-dominated envelopes, and smaller rocky planets, which suggests a potentially metal-enriched atmosphere composition. We leverage transit observations of GJ 9827 d's atmosphere with JWST NIRISS/SOSS to infer that its atmospheric composition is highly enriched in high mean molecular weight volatiles, including large amounts of water, and is hydrogen-poor compared to slightly larger planets. We propose observational diagnostics to further constrain the origin of this metal enrichment, which could originate from large initial amounts of accreted volatiles, magma ocean-atmosphere geochemistry, or gradual loss of lighter atmosphere constituents over time. The fourth and final work presented in this thesis focuses on a small temperate 0.8-Earth-radius rocky exoplanet, TRAPPIST-1 d. We observe its transmission spectrum using JWST NIRSpec/PRISM, and do not detect any planetary atmosphere signature, despite our high sensitivity to even thin, high mean molecular weight secondary atmospheres. We propose that TRAPPIST-1 d has either been stripped of its atmosphere by the intense irradiation it receives from its host star, or that it has very small spectral features from a high mean molecular weight atmosphere with an extremely low surface pressure, or with high-altitude clouds obscuring the signatures from a deeper atmosphere. These studies highlight only a modest subset of the breadth of information that can be uncovered by detailed observational studies supported by rigorous modeling approaches, revealing the nature of exoplanets and their atmospheres. With more and more precise atmospheric characterization of a growing sample of exoplanets enabled by new telescopes such as the JWST, we can now hope to build a statistical sample of well-characterized exoplanet atmospheres that will undoubtedly further challenge our models and assumptions, and bring us one step closer to understanding the factors underlying their diversity.

Les amas globulaires contiennent deux classes de sources X se différenciant par leur luminosité. Tout d'abord, les sources X brillantes (Lx>10^36 ergs/s), qui sont des binaires X de faible masse identiques à celles contenues dans le disque galactique. La seconde classe regroupe les objets de luminosité X faible (LX<10^34.5 ergs/s). Elle est composée d‟objets de natures diverses, principalement des systèmes binaires où l'accrétion de matière sur l'un des deux composants (une étoile à neutrons, une naine blanche) est responsable de l'émission X observée. Déterminer la population de sources X des amas globulaires permet donc d'étudier les mécanismes de formation des systèmes binaires, lesquels jouent un rôle fondamental dans l'évolution des amas globulaires en assurant leur équilibre dynamique. Cette thèse est centrée sur l'étude des populations X de 4 amas globulaires observés avec les satellites XMM-Newton ou Chandra : Omega Cen, M13, M22 et NGC 6366. Notre échantillon nous a permis d‟étudier les populations de sources X faibles et de tester les scénarii de formation des binaires en fonction de divers paramètres comme la masse, la taille et la densité stellaire de l‟amas. Nous avons associé des sources X faibles à chaque amas (respectivement 30, 5, 2 et 1). Ces sources se trouvent dans le coeur des amas. Nous avons également détecté un excès significatif de sources dans les régions externes d‟Omega Cen. Nous avons enfin découvert une binaire X de faible masse avec une étoile à neutrons dans M13 (sa contrepartie a été recherchée dans les données du télescope spatial Hubble). Nous montrons que le nombre de binaires X de faible masse avec une étoile à neutrons contenues dans un amas est corrélé avec le taux de collision stellaire. Ceci pourrait indiquer que ces binaires sont formées par la capture gravitationnelle par une étoile à neutrons d‟un autre astre dans le coeur des amas. Nous avons également étudié les mécanismes de formation des autres catégories de binaires.