Pendant mes trois ans de doctorat j'ai eu le plaisir de travailler sur trois projets très variés ayant un but commun: mieux contraindre certains modèles de nouvelle physique entre cosmologie et le LHC. Le fait que les densités reliques de matière noire et de baryons sont similaires semble indiquer qu'il y a un lien entre les deux. Nous essayons d'expliquer les valeurs observées en reliant un modèle de leptogenèse au miracle des WIMPs, qui produit naturellement la bonne densité relique. Si l'asymétrie baryonique est produit dans des désintégrations hors équilibre à l'échelle électro-faible et si la matière noire est constituée de WIMPs, les deux densités reliques sont contrôlées par des processus électro-faibles hors équilibre. Je construis un modèle de leptogenèse à l'échelle du TeV en utilisant une extension du type seesaw inverse du modèle standard avec des singlets additionnels. Pour produire suffisamment d'asymétrie baryonique il faut une violation CP ~ O(1) qui est difficile à obtenir dans mon cadre. Les axions, tout comme les WIMPs sont de bons candidats de matière noire bien motivés. Il serait très utile de pouvoir les distinguer. Sikivie argumente que si des axions sont dans un condensat de Bose-Einstein, alors ils forment des halos galactiques différents des halos de WIMPs. D'après Sikivie ce sont les interactions gravitationnelles qui thermalisent les axions et qui les condensent. La formation d'un condensat nécessite la génération d'entropie qui ne peut pas être fourni par les interactions gravitationnelles au premier ordre. J'étudie la génération d'entropie par les interactions gravitationnelles en estimant une longueur de dissipation dans le fluide d'axions qui vient de la présence d'une pression anisotrope. Je ne peux pas confirmer la thermalisation rapide d'axions causé par leurs interactions gravitationnelles. Des nouveaux bosons de jauges comme le Z0 apparaissent dans un grand nombre d'extensions du modèle standard. On les recherche le plus souvent comme une résonance dans le spectre de masse invariante de leurs produits de désintégration. Le Z0 doit être produit sur couche de masse dans ces recherches résonantes. Mais la présence d'un Z0 peut aussi influencer d'autres observables cinématiques sans être produit directement, ce qu'on peut utiliser dans des recherches non-résonantes. Je compare ces deux types de recherches au LHC et trouve que pour des petits couplages les recherches résonantes sont plus adaptées mais pour de plus grandes masses et couplages les recherches non-résonantes sont plus performantes.

In a context of growing energy prices and climate change mitigation, the thesis addresses the issues of investments in power generation capacities and in particular nuclear capacities. Given that the Generation IV of nuclear reactors is supposed to be ready in 2040 for industrial deployment, the purpose of the thesis is to study the conditions for electricity investments in France and Europe within this horizon, in order to assess development perspectives for nuclear energy and for potential emergence of Generation IV on the European market. To do so, it is necessary to study the mechanisms at stake in investment choices taking into account all power generating technologies. Economic theory usually bases the choice on long-term economic rationality, which does not allow explain the actual choices observed in European electricity mix. The objective of the research work is thus to identify investment choice drivers and to propose an approach describing the behavior of investors in a more realistic way. A multidisciplinary approach was adopted to explore the question. It combines a historical analysis of drivers evolution according to historical context, a structural analysis of these drivers to identify favorable scenarios for future nuclear reactors, a value creation approach to replicate investors' preferences in those scenarios, and last, a value option approach focusing on nuclear technologies and comparing competitiveness of Generation IV reactors with current reactors. As a result, only strong climate policy combined to government support to nuclear energy could allow industrial development of Generation IV, while high progress of renewables does not lessen the attractiveness of nuclear energy.On a international level, such analysis could be broaden by taking into account the drivers specific to each area of the world, such as highly growing demand in developing countries.

Ce travail porte sur la précession du spin d’électrons chauds polarisés en spin. Celle-ci est induite par le champ d’échange d’une couche mince ferromagnétique dans une structure multicouche. La précession du spin électronique a déjà été mesurée dans des matériaux ferromagnétiques mais uniquement pour des électrons qui possèdent une énergie supérieure à 4eV au-dessus du niveau de Fermi. L’objectif premier de cette thèse est de mesurer la précession du spin de l’électron pour des faibles énergies, comprises entre 0.7eV et 2eV au-dessus du niveau de Fermi. Pour ce faire, un transistor tunnel magnétique comportant trois couches magnétiques avec les aimantations qui pointent dans les trois directions de l’espace doit être construit. Les électrons sont injectés à basse énergie grâce à une jonction tunnel. Une diode Schottky (interface entre du Cu et du Si) filtre en énergie les électrons incidents, permettant uniquement aux électrons balistiques de contribuer au courant mesuré dans le semi-conducteur. Le premier travail a consisté à obtenir une couche magnétique exhibant une anisotropie perpendiculaire. Ainsi, nous avons réussi à faire croître une multicouche de Co et Ni sur une diode Schottky qui possède une anisotropie perpendiculaire jusqu’à 5 répétitions. Le deuxième travail réalisé dans cette thèse était d’optimiser le magnéto-courant d’une la vanne de spin. En effet, le magnéto-courant détermine la sensibilité de notre transistor tunnel magnétique. Nous avons notamment démontré ici que le magnéto-courant augmente avec le nombre de répétitions de la multicouche [Co/Ni], pour atteindre quasiment le maximum de 100% théoriquement prédit dans une vanne de spin à aimantations croisées. Enfin, le troisième travail de cette thèse résidait dans l’étude de la précession du spin de l’électron dans différents matériaux ferromagnétiques. Cet effet a été mis en évidence ici pour des couches à aimantation planaire composée de Co, de CoFeB, ainsi que pour un alliage de CoAl et ceci en fonction de leur épaisseur / This work is about polarised hot electrons spin precession. This phenomenon is induced by the exchange field of a ferromagnetic thin film in a multilayer structure. The electronic spin precession has already been measured in ferromagnetic materials, but only for electrons whose energy is more than 4eV over the Fermi level. The initial aim of this PhD work is to measure the electron spin precession for weak energies, between 0.7 eV and 2eV over the Fermi level. In order to achieve that, a magnetic tunnel transistor composed of three magnetic layers with their magnetisations directions perpendicular to each other has to be elaborated. The electrons are injected at low energy by means of a tunnel junction. A Schottky diode (interface between Cu and Si) filters the incident electrons by their energies, which enables only ballistic electrons to contribute to the measured current in the semi-conductor. The first task consisted in obtaining a magnetic layer showing perpendicular magnetic anisotropy. We succeeded in growing cobalt nickel multilayers exhibiting a perpendicular magnetic anisotropy up to five repetitions. The second part of the job carried out during this PhD was to optimise the magneto-current of a spin valve. Indeed, it determines the magnetic tunnel transistor sensitivity. We have demonstrated that the magneto-current increases with the number of repetitions of the [Co/Ni] multilayer up to a maximum of nearly a hundred percent, which is the maximum theoretically predicted in a spin valve with crossed magnetisations. Eventually, the third task of this PhD was the study of the electron spin precession in various ferromagnetic materials. This effect has been evidenced here for thin layers with in-plane magnetisations composed of Co, CoFeB, and also for a CoAl alloy depending on the thickness of the layers

abstract: Na+/H+ antiporters are vital membrane proteins for cell homeostasis, transporting Na+ ions in exchange for H+ across the lipid bilayer. In humans, dysfunction of these transporters are implicated in hypertension, heart failure, epilepsy, and autism, making them well-established drug targets. Although experimental structures for bacterial homologs of the human Na+/H+ have been obtained, the detailed mechanism for ion transport is still not well-understood. The most well-studied of these transporters, Escherichia coli NhaA, known to transport 2 H+ for every Na+ extruded, was recently shown to bind H+ and Na+ at the same binding site, for which the two ion species compete. Using molecular dynamics simulations, the work presented in this dissertation shows that Na+ binding disrupts a previously-unidentified salt bridge between two conserved residues, suggesting that one of these residues, Lys300, may participate directly in transport of H+. This work also demonstrates that the conformational change required for ion translocation in a homolog of NhaA, Thermus thermophilus NapA, thought by some to involve only small helical movements at the ion binding site, is a large-scale, rigid-body movement of the core domain relative to the dimerization domain. This elevator-like transport mechanism translates a bound Na+ up to 10 Å across the membrane. These findings constitute a major shift in the prevailing thought on the mechanism of these transporters, and serve as an exciting launchpad for new developments toward understanding that mechanism in detail. / Dissertation/Thesis / Doctoral Dissertation Physics 2016

Le but de cette thèse est le développement et l'optimisation de la chaine électrique d'une hydrolienne fluviale. L'approche est d'abord traitée en simulation pour ensuite finir par la conception et la mise au point d'un prototype. La partie simulation concerne la modélisation des ensembles turbines, génératrices et électronique de puissance mais aussi le développement des diverses lois de commandes. Ces commandes peuvent intervenir à différents niveaux du contrôle jusqu'à la supervision complète du système, permettant de gérer des défauts, des algorithmes de MPPT (extraction maximale de puissance), des synchronisations entre colonne, ... Le prototype d'hydrolienne fluviale sera ensuite présenté, de la mise au point des parties mécaniques jusqu'aux résultats expérimentaux. Les travaux nombreux autour de ce prototype ont permis d'obtenir des résultats satisfaisants et encourageants qui corroborent la théorie. / The purpose of this thesis is the development and optimization of the electrical system of a fluvial cross-flow current turbine. The approach is first treated in simulation and then eventually with the design and development of a prototype. The simulation section deals with the modeling of turbines groups, generators and power electronics, as well as the development of various control laws. These controls may have an influence at different levels of the control strategies up to the complete system supervision for fault management, MPPT (maximum power extraction) algorithms, turbine columns synchronization... The fluvial cross-flow current turbine prototype will then be presented, from the development of the mechanical parts to the experimental results. The various works involving the prototype have yielded satisfactory and encouraging results that corroborate the theory.

Dans un contexte de hausse de prix des énergies et de protection du climat, la thèse s’intéresse à l’investissement dans des capacités électrique, en particulier dans le nucléaire. Partant de l’hypothèse où la Génération IV de réacteurs nucléaires serait prête autour de 2040 pour un déploiement industriel, l’objet de la thèse est d'analyser les conditions d'investissement et de développement de capacités de production d'électricité en France et en Europe à cet horizon, afin d’évaluer les perspectives de développement du nucléaire sur le marché électrique européen et le potentiel développement de la Génération IV. Pour ce faire, le travail de recherche nécessite de prendre du recul et d’étudier de manière générale, en prenant en compte toutes les technologies de production d’électricité, les mécanismes entrant en jeu dans le choix d’investissement de l’électricien lorsqu’il s’agit de renouveler ou d’étendre son parc de production. L’approche économique classique basant généralement le choix de l’investisseur sur une rationalité économique de long terme, elle ne permet pas d’expliquer les choix effectifs constatés dans les mix électriques d’un pays à l’autre. L’objectif de cette thèse est d’identifier les déterminants des choix d’investissement dans des capacités électriques et de proposer une approche permettant de décrire le comportement du choix de l’investisseur allant au-delà du critère classique de rationalité économique de long terme. Une approche pluridisciplinaire a été adoptée pour répondre à la question posée. Elle combine une analyse historique de l’évolution des déterminants des choix en fonction du contexte, une analyse structurelle permettant d’identifier les scénarios les plus favorables à l’émergence de futurs réacteurs nucléaires, une approche de création de valeur permettant proposant de reproduire les préférences des électriciens en fonction des déterminants, et enfin une approche par la théorie des options réelles pour comparer les compétitivités respectives des futurs réacteurs nucléaires de Génération IV avec celle des réacteurs actuels. Il en résulte que des politiques pro-nucléaires seules ne seraient pas suffisantes, mais que seule une politique climatique forte permettrait réellement l’émergence des réacteurs sur le marché. De fort progrès technologiques dans le domaine des renouvelables ne sont pas antinomiques avec le développement de nouveaux réacteurs. A un niveau international, cette analyse pourrait être élargie en prenant en compte les déterminants spécifiques aux autres régions du monde, comme la forte croissance de la demande en électricité des pays émergents. / In a context of growing energy prices and climate change mitigation, the thesis addresses the issues of investments in power generation capacities and in particular nuclear capacities. Given that the Generation IV of nuclear reactors is supposed to be ready in 2040 for industrial deployment, the purpose of the thesis is to study the conditions for electricity investments in France and Europe within this horizon, in order to assess development perspectives for nuclear energy and for potential emergence of Generation IV on the European market. To do so, it is necessary to study the mechanisms at stake in investment choices taking into account all power generating technologies. Economic theory usually bases the choice on long-term economic rationality, which does not allow explain the actual choices observed in European electricity mix. The objective of the research work is thus to identify investment choice drivers and to propose an approach describing the behavior of investors in a more realistic way. A multidisciplinary approach was adopted to explore the question. It combines a historical analysis of drivers evolution according to historical context, a structural analysis of these drivers to identify favorable scenarios for future nuclear reactors, a value creation approach to replicate investors’ preferences in those scenarios, and last, a value option approach focusing on nuclear technologies and comparing competitiveness of Generation IV reactors with current reactors. As a result, only strong climate policy combined to government support to nuclear energy could allow industrial development of Generation IV, while high progress of renewables does not lessen the attractiveness of nuclear energy.On a international level, such analysis could be broaden by taking into account the drivers specific to each area of the world, such as highly growing demand in developing countries.

Neste trabalho é apresentado um modelo algébrico para o cálculo de energias de ligação de núcleos pesados com N = Z baseado nas versões invariantes por isospin do Modelo de Bósons interatuantes (IBM). Com a utilização de uma interação adequada para a descrição dos modos isoescalar e isovetorial do emparelhamento nuclear adicionada àquelas interações que descrevem globalmente uma dada região de massa, foram ajustados os parâmetros da hamiltoniana e calculados núcleos com N = Z ao longo das camadas sd e pf. Deste modo, pôde-se fazer algumas predições, para suas massas do estado fundamental e para estados excitados, que oferecem um desafio às novas gerações de feixes radiativos que estão por vir. / In this work we present an algebraic model for calculating the binding energies of heavy nuclei with the same number of protons and neutrons which is based in the isospin invariant versions of the Interacting Boson Model (IBM). With an adequate interaction for the description of the isoscalar and isovector pairing modes of the residual nuclear interaction added to those terms responsible for the bulk properties of a given mass region, we have fitted the parameters of our algebraic Hamiltonian and have calculated nuclei with N=Z along the sd and pf shells. Therefore we were able to make some predictions, for their ground state masses as well as for the excited states, which offer a challenge to the new generations of radioactive nuclear beams.

Radioactive beams of 8Li and 6He were produced using the double superconducting solenoid system of RIBRAS (Radioactive Ion Beams in Brasil) with a primary beam of 7Li of Elab = 30 MeV, at the São Paulo Pelletron Accelerator. The production reactions were 9Be(7Li, 8Li)8Be and 9Be(7Li, 6He)10B. The angular distributions of the elastic scattering of the 8Li radioactive beam of 26.0 MeV and 6He radioactive beam of 23.0 MeV were measured on 51V target of 1.9 mg/cm2.The elastic scattering angular distributions were analyzed using Optical Model, where the real and imaginary parts are described through a Non-Local Interaction Model called São Paulo Potential . The results were compared with the data present in the literature. The largest cross section, particularly for the halo 6He, shows evidence of the importance of the break up for these medium mass systems. [1]R. Lichtenthaler et al, Eur. Phys. J. A 25,s01,733 (2005); [2]L.C. Chamon et al, Phys. Rev. C66 (2002) 014610. / Radioactive beams of 8Li and 6He were produced using the double superconducting solenoid system of RIBRAS (Radioactive Ion Beams in Brasil) with a primary beam of 7Li of Elab = 30 MeV, at the São Paulo Pelletron Accelerator. The production reactions were 9Be(7Li, 8Li)8Be and 9Be(7Li, 6He)10B. The angular distributions of the elastic scattering of the 8Li radioactive beam of 26.0 MeV and 6He radioactive beam of 23.0 MeV were measured on 51V target of 1.9 mg/cm2.The elastic scattering angular distributions were analyzed using Optical Model, where the real and imaginary parts are described through a Non-Local Interaction Model called São Paulo Potential . The results were compared with the data present in the literature. The largest cross section, particularly for the halo 6He, shows evidence of the importance of the break up for these medium mass systems. [1]R. Lichtenthaler et al, Eur. Phys. J. A 25,s01,733 (2005); [2]L.C. Chamon et al, Phys. Rev. C66 (2002) 014610.

Orientador: Rogerio Custodio / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-14T02:16:55Z (GMT). No. of bitstreams: 1 Streit_Livia_M.pdf: 2107026 bytes, checksum: 23d8f89115d585808f6950c1959f329b (MD5) Previous issue date: 2009 / Resumo: Os métodos Monte Carlo Quântico (MCQ) são métodos estocásticos de resolução da equação de Schrödinger que vêm se mostrando como uma alternativa recente e promissora para o cálculo de propriedades eletrônicas. Dentre esses métodos, o Monte Carlo Quântico de Difusão (MCQD) é um dos mais utilizados e baseia-se na solução da equação de Schrödinger dependente do tempo através de um processo de difusão. Neste trabalho investigamos a aplicabilidade do método Monte Carlo Quântico de Difusão no cálculo de energias de ionização de valência e camada interna para moléculas simples, com o intuito de desenvolver uma metodologia simples e segura para a obtenção de valores precisos. Para tanto, foram estudadas as energias de ionização simples e duplas, além das energias de transição Auger das moléculas CH4, NH3, H2O e HF. Ainda, foram estudadas as energias de ionização simples das moléculas OH, NH, CH, BH, BeH e LiH. As energias de ionização foram calculadas por diferença de energia entre os sistemas neutro e ionizado. Estudos preliminares envolvendo as energias de ionização sucessivas dos átomos do He ao Ne também foram realizados, bem como estudos complementares das energias de ionização simples de moléculas mais complexas, CO, NO e H2CO. As principais avaliações do método para o cálculo de energias de ionização dizem respeito à função de onda, especialmente à inclusão de funções de correlação eletrônica explícita, e à escolha de funções de base simples. Os resultados obtidos podem ser considerados excelentes, visto que apresentam desvios em relação aos dados experimentais aceitáveis, menores que a incerteza experimental. Desvios absolutos médios de 0,05 a 0,5 eV foram obtidos para as ionizações sucessivas dos átomos, de 0,04 a 1,5 eV para as ionizações simples, e de 1,1 a 2,3 eV para duplas e de transição Auger. Na maioria dos casos os desvios são menores ou da mesma ordem que os apresentados por métodos de cálculo de estrutura eletrônica de alto nível. Os resultados obtidos neste trabalho são confiáveis e podem ser usados como uma ferramenta auxiliar e determinante na interpretação de espectros fotoeletrônicos, o que evidencia a eficiência do método Monte Carlo Quântico de Difusão no cálculo de energias de ionização para as moléculas estudadas. Assim, pode-se vislumbrar o uso do MCQD em sistemas mais complexos e a obtenção de excelentes resultados / Abstract: The Quantum Monte Carlo Methods (QMC) are stochastic methods that solve the Schrödinger equation and emerge as a recent and promising alternative for the calculation of electronic properties. The most common QMC method is the Diffusion Quantum Monte Carlo (DQMC) and is based on the solution of the time dependent Schrödinger equation by a diffusion process. In this work we investigate the applicability of DQMC to calculate inner and valence shells ionization energies in simple molecules seeking a simple and safe procedure where accurate results are obtained. For this purpose, we studied single and double ionization energies and also Auger transition energies for CH4, NH3, H2O and HF molecules. The single ionization energies for OH, NH, CH, BH, BeH and LiH molecules were also investigated. The ionization energies were calculated as the difference between the ionized species and the neutral one. Studies about successive ionization from He to Ne and about single ionization for more complex molecules CO, NO and H2CO were also carried out. The main goal is to investigate the application of DQMC method using simple guide wave functions and modest electronic correlation factor. The obtained results are in good agreement with the experimental spectra. The average absolute error with respect to the experimental data are admissible, lower than experimental uncertainty. Average absolute errors from 0.04 to 0.5 eV were obtained for successive ionization energies for atoms, 0.05 to 1.5 eV for single ionizations, and from 1.1 to 2.3 eV for double and Auger ionizations energies. In most of the cases, the deviations are lower than or have the same order of magnitude of the deviations presented by other compared methods. The obtained results are reliable and may be used as an auxiliary and reliable tool in photoelectron spectra elucidation. Therefore, even using simple guide wave functions and modest explicit electronic correlation function, the DQMC method revealed significant efficiency in the calculation of single, double and Auger ionization energies for simple molecules. The present applications suggest that DQMC may be an excellent alternative for the calculation of ionization energies for more complex systems / Mestrado / Físico-Química / Mestre em Química

CoordenaÃÃo de AperfeiÃoamento de NÃvel Superior / FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / Because of the lack of drinkable water in various semi-arid regions and the necessary use of renewable energies, the present work presents a performance study of a heat recovery tower to operate in a solar desalination unit for decentralized water production. The solar desalination unit has two parts: a heating unit and a desalination unit.This work presents the field results with a desalination tower with synthetic (polyurethane) flow channels. The tower operation consists of the heating of salty water, the evaporation of desalinated water vapor in the lower stage, and the vapor condensation on the above stage. The condensate flows to a lateral channel to be collected, while the salty water in the trays is heated by the heat transfer processes, particularly the condensation from the tray below. The heating, evaporation, and condensation processes are repeated among the trays in a heat recovery mechanism. The results also show the correlation parameters for the Sherwood number, developed using the experimental data gathered in a temperature controlled laboratory desalination unit. This correlation was used as a reference in the study of heat recovery towers. The solar dealination system is working properly and showed a daily production of 35 liters. The results present the production per stage and the temperature profiles, in graphical form. For the performance parameters, a GOR value of 1,26 and a COP value of 4,78 were measured. The Sherwood correlation was used to compare experimental and simulated values. / Diante da crescente escassez de Ãgua potÃvel em vÃrias regiÃes semi-Ãridas, e a necessidade de avanÃo na utilizaÃÃo de fontes de energias renovÃveis, o presente trabalho apresenta o estudo do desempenho de uma torre de recuperaÃÃo de calor para operar com um dessalinizador solar que possa ser utilizado para a produÃÃo descentralizada de Ãgua potÃvel. O dessalinizador solar estudado possui duas unidades bÃsicas: a unidade de aquecimento e a unidade de dessalinizaÃÃo. O trabalho apresenta os resultados alcanÃados com uma torre de recuperaÃÃo de calor com canais sintÃticos de poliuretano. A operaÃÃo da torre consiste no aquecimento e evaporaÃÃo de Ãgua salobra armazenada em um estÃgio inferior, que condensa na parte inferior da bandeja do estÃgio acima. O condensado escoa para uma calha lateral de onde à coletado, enquanto a Ãgua armazenada na bandeja à aquecida devido aos processos de transferÃncia de calor, pricipalmente ao processo de condensaÃÃo. O processo de evaporaÃÃo, condensaÃÃo e aquecimento de Ãgua se repete entre as bandejas contidas nos estÃgios da torre de recuperaÃÃo de calor, em um total de cinco estÃgios. Os resultados apresentam ainda os coeficientes de uma correlaÃÃo para o nÃmero de Sherwood, desenvolvida a partir de uma unidade de dessalinizaÃÃo de laboratÃrio, operando em temperaturas controladas, para ser usada como modelo de referÃncia na determinaÃÃo do desempenho de torres de recuperaÃÃo de calor. O dessalinizador està em funcionamento e a torre de recuperaÃÃo de calor apresentou bons resultados alcanÃando uma produÃÃo de 35 litros de Ãgua dessalinizada por dia. Os resultados da produÃÃo por estÃgio e dos perfis de temperatura do dessalinizador estÃo apresentados na forma de grÃficos. Os parÃmetros de desempenho foram calculados e alcanÃados os valores de 1,26, para o GOR do dessalinizador e 4,78 para o COP. A correlaÃÃo para o nÃmero de Sherwood foi desenvolvida e foram comparados os valores experimentais com os valores obtidos pela correlaÃÃo.