A Produção Enxuta vem sendo aplicada em diversos setores, e a implantação dos seus princípios e práticas, elimina perdas nos processos e contribui para manter a competividade das empresas. Desse modo, o objetivo principal desta dissertação é desenvolver um modelo econômico-probabilístico que auxilie a seleção e priorização de projetos de produção enxuta. Este modelo quantifica os investimentos, benefícios e incertezas associadas através de uma análise econômica-probabilística que apresenta o retorno esperado dos projetos. Com base nesse retorno, a priorização dos projetos de produção enxuta torna-se mais precisa de ser executada pelos tomadores de decisão. O modelo contém 38 critérios qualitativos e quantitativos, os quais estão divididos em: (i) descrição do projeto, (ii) quantificação dos investimentos e (iii) quantificação dos benefícios. Para atingir o objetivo deste trabalho, foram necessárias cinco etapas: (i) selecionar os principiais critérios para avaliação de projetos de produção enxuta; (ii) escolher o método para seleção e priorização dos projetos de produção enxuta; (iii) estruturar um modelo genérico que avalie o retorno e o impacto das incertezas envolvidas no resultado dos projetos de produção enxuta, baseado nos critérios e método selecionados nas etapas anteriores; (iv) aplicar o modelo em uma empresa; (v) analisar e verificar os resultados da aplicação prática para validar o modelo desenvolvido. A principal contribuição desta dissertação é fornecer ao tomador de decisão um modelo que o auxilie a quantificar o retorno dos projetos de produção enxuta, combinando métodos econômicos e probabilísticos. Os métodos econômicos são de fácil entendimento e mais amigáveis aos tomadores de decisão, já os métodos probabilísticos avaliam as incertezas associadas aos projetos de produção enxuta, permitindo uma visão mais completa do retorno esperado. / Lean Manufacturing has been applied in several sectors and the implementation of its principles and practices eliminate losses in the processes, contributing to sustain companies’ competitiveness. Thus, this thesis main objective is to develop an economic-probabilistic model to aid lean manufacturing projects selection and prioritization. This model quantifies the investments, benefits and associated uncertainties based on an economic-probabilistic analysis, which presents the projects expected return. With the expected return, lean manufacturing projects prioritization becomes more precise to be performed by decision makers. The model contains 38 qualitative and quantitative criteria, divided into: (i) project description, (ii) investment quantification and (iii) benefits quantification. To achieve this study’s objective, five steps were performed: (i) selecting the main criteria for lean production projects evaluation; (ii) choosing the method for lean manufacturing projects selection and prioritization; (iii) developing a generic model to evaluate return and associated uncertainties impact on results of lean manufacturing projects, based on the criteria and method selected in previous steps; (iv) applying the model in a company; (v) analyzing and verifying the results from practical application to validate the developed model. The main contribution of this study is to provide to the decision maker a model to quantify lean manufacturing projects returns, connecting economic and probabilistic methods. Economic methods are easy to understand and more user-friendly to decision makers and probabilistic methods can evaluate associated uncertainties on lean manufacturing projects, allowing a more complete vision of the expected returns.

Este trabalho propõe um modelo para a simulação do passivo atuarial de um fundo de pensão brasileiro. As principais fontes de incertezas que influenciam a avaliação do passivo atuarial foram especificadas como variáveis aleatórias e parâmetros do modelo. Diversos cenários são gerados utilizando a técnica de simulação de Monte Carlo e a microssimulação no intuito de determinar o status de cada participante do fundo de pensão modelo para períodos futuros em diferentes nós de uma árvore de cenários. A situação de vida de cada participante, simulada individualmente a cada nó, está condicionada ao seu estado no nó imediatamente antecessor. O resultado é um modelo flexível, que permite a configuração de parâmetros a níveis individuais e possibilita trabalhar com diversas tábuas biométricas, mostrando-se capaz de gerar cenários consistentes, realistas e variados, capturando a essência da incerteza inerente às entidades de previdência complementar e produzindo não só valores únicos e determinísticos de reservas matemáticas e fluxos de caixa atuariais, mas intervalos de valores possíveis com distribuições conhecidas, importantes para a gestão eficiente de um fundo de pensão. A metodologia proposta serve como alternativa ao cálculo atuarial tradicional, que utiliza diretamente as probabilidades das tábuas biométricas, fixas por idade e sexo, para a mensuração dos fluxos de caixa previdenciários e reservas matemáticas. Os dados gerados a partir das simulações servem como dados de entrada para um modelo estocástico completo de Asset-Liability Management (ALM). / This study proposes a model to simulate actuarial liabilities from a pension fund in Brazil. The main uncertainties that affect the liabilities have been specified as random variables and parameters of the developed model. Many scenarios are generated using Monte Carlo simulation and micro-simulation techniques in order to determine the status of each member of the pension fund for future periods in different nodes of a scenario tree. The future of each participant, simulated individually at each node, is conditioned to its status in the immediately predecessor node. The result is a flexible model which allows the parameters configuration at individual levels and that can work with several actuarial tables, showing to be itself able to generate consistent, realistic and sorted scenarios, capturing the uncertainty inherent in pension funds environment and producing not only single and deterministic values for actuarial liabilities and cash flows, but ranges of possible values with known distributions, becoming an important tool for the efficient management of the pension fund. The methodology applied is an alternative to the classic actuarial techniques, that use directly the probabilities from actuarial tables, fixed by age and gender, to calculate the liabilities and the cash flow of the pension fund. The data generated by this model were thought to be inputs for a full multistage stochastic Asset-Liability Management (ALM) model.

Orientador: Prof. Dr. Ricardo Caneloi dos Santos / Dissertação (mestrado) - Universidade Federal do ABC. Programa de Pós-Graduação em Energia, 2015. / Este projeto de pesquisa estabelece uma metodologia para determinar os índices de confiabilidade/disponibilidade em subestações de energia elétrica, partindo da necessidade de tornar as operações de manutenção mais eficazes mitigando os impactos ambientais, sociais, econômicos e técnicos provocados pelos cortes de fornecimento de energia elétrica. A metodologia utilizada baseia-se em dois métodos normalmente utilizados individualmente em estudos de confiabilidade. O método denominado Árvore de Falhas que proporciona um modelo lógico de possíveis combinações de falhas para um evento principal, e a simulação de Monte Carlo que possibilita estimar os índices de interesse do sistema elétrico pela geração aleatória dos diferentes estados do sistema (operação, falha ou manutenção). Considerando este contexto, neste trabalho de pesquisa são identificados os pontos vulneráveis, a probabilidade de falha e a indisponibilidade de cada subestação, com o objetivo de elevar os índices de confiabilidade, elevar a vida útil dos componentes e proporcionar um esquema otimizado de manutenção preventiva para as concessionárias. Consequentemente, o resultado desse trabalho visa diminuir a frequência dos cortes de energia não programados e seus respectivos impactos ambientais, sociais e econômicos produzidos pelo não fornecimento de energia elétrica. Nesse sentido, uma discussão sobre os impactos das falhas elétricas para sociedade também é realizada. / This work provides a methodology to determine the levels of reliability/availability in electrical substations, based on the need to improve the efficiency of maintenance operation reducing negative environmental, social, economic and technical impacts, caused by power outages. The methodology is based on two methods typically used individually in reliability studies. The method called Fault Tree that provides a logical model of possible failure combinations for a major event, and the Monte Carlo simulation used to determine the power system index by random generation of the different states of the system (operation, failure or maintenance). Considering this context, in this work are identified vulnerabilities points, the probability of failure and the unavailability of each substation, in order to increase the reliability indices, increase the service life of components and provide a better preventive maintenance scheduled. Consequently, this works seeks to decrease the frequency of uncontrolled power cuts and their environmental, social and economic impacts produced by nonsupply of electricity. In this sense, a discussion about the impacts of electrical faults to society is also conducted.

Submitted by MARIA LUISA VICHI DE CAMPOS FARIA null (ml.vichi@gmail.com) on 2016-04-09T19:42:20Z No. of bitstreams: 1 tese-da-luisa(8).pdf: 6093134 bytes, checksum: a6a13acbe1b7e8b23ecfbb267b89b802 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-04-12T14:38:04Z (GMT) No. of bitstreams: 1 faria_mlvc_dr_bot.pdf: 6093134 bytes, checksum: a6a13acbe1b7e8b23ecfbb267b89b802 (MD5) / Made available in DSpace on 2016-04-12T14:38:04Z (GMT). No. of bitstreams: 1 faria_mlvc_dr_bot.pdf: 6093134 bytes, checksum: a6a13acbe1b7e8b23ecfbb267b89b802 (MD5) Previous issue date: 2016-03-01 / O álcool, mesmo proibido, é a substância psicoativa mais usada por adolescentes no Brasil. Em 2011 uma pesquisa nacional (PeNSE) encontrou que mais da metade dos adolescentes de 13 a 15 anos já havia experimentado álcool e que 9\% referiu problemas decorrentes do uso. Esse comportamento pode trazer consequências graves e permanentes para a vida do adolescentes e de outras pessoas. Trata-se de um problema de saúde pública sendo necessários avanços nas pesquisas sobre prevenção e sobre os cuidados específicos para essa população. O BASICS foi concebido para universitários que apresentavam padrão de uso de álcool problemático. Essa intervenção, empática e flexível, foi desenhada para ajudar esses indivíduos na tomada das melhores decisões sobre o álcool, caracterizando-se assim, como uma abordagem de redução de danos e também uma tecnologia leve. O objetivo desse estudo foi testar a efetividade do BASICS na redução do uso problemático de álcool em uma amostra de alunos do ensino médio de escolas públicas de uma cidade de 127 mil habitantes do estado de São Paulo-Brasil. Foi realizada uma análise do banco de dados de um ensaio controlado randomizado realizado ao longo do ano de 2009. De todos os alunos matriculados nas escolas públicas, 1712 eram menores de 18 anos e aceitaram fazer parte do estudo. Destes, 1149 eram abstêmios, 253 faziam uso arriscado de álcool e 310 foram considerados de baixo risco. Os indivíduos identificados com uso de risco foram sorteados para os grupos de intervenção breve (IB) ou para o grupo controle (C). O grupo C apenas preencheu os instrumentos de avaliação. Os grupos IB e C foram então avaliados após 6 e 12 meses. Não se encontrou diferença com relevância estatística entre as médias do AUDIT e AUDITC entre os grupos. Houve redução de consumo de álcool ao longo do estudo em ambos os grupos. Essa redução pode ser explicada parcialmente pelo fenômeno de regressão à media. Essa redução não se deu em função das perdas pois os alunos que abandonaram não foram aqueles com padrões mais graves de uso. Na tentativa de explicar os resultados encontrados foram levantadas as seguintes possibilidades: presença do efeito Hawthorne e a ocorrência de uma redução natural no consumo ao longo dos 12 meses em função do comportamento exploratório e não estático do uso de álcool por adolescentes. Notou-se também que uma fração considerável de sujeitos evoluiu de um consumo de risco para a abstinência ao longo do estudo. Para melhor descrever esse processo foi proposto um modelo markoviano que incluiu de forma explícita o comportamento exploratório dos adolescentes e sua tendência à abstinência. Através de simulações de Monte Carlo foram estimados os parâmetros relevantes do modelo e investigada a presença do efeito Hawthorne. Por meio dessa análise constatou-se que houve uma redução do uso de álcool no grupo controle e no grupo intervenção estimulada pela participação no estudo, que os padrões de uso em ambos os grupos foram essencialmente os mesmos e que as distribuições de consumo podem ser adequadamente descritas pelo modelo proposto. Foi investigado também se parte dessa população não teria um comportamento que pudesse indicar sua predisposição para um consumo de risco em fases posteriores na vida. A partir de um modelo de clusterização de dados baseados na variável AUDIT percebeu-se que os sujeitos poderiam ser divididos em dois grupos: persistente e não persistente. Por meio de uma análise estatística usando modelos lineares generalizados conclui-se que adolescentes do sexo masculino, que iniciavam o consumo mais cedo, que possuíam amigos que se embriagavam e que eram oriundos de famílias com problemas de álcool eram mais propensos a participar do grupo persistente. Conhecer melhor o comportamento dos adolescentes quanto ao uso de álcool favorecerá o uso de desenhos experimentais mais adequados o que possibilitará uma melhor avaliação do impacto de medidas preventivas para essa população. / Alcohol, even banned is the most used psychoactive substance among adolescents in Brazil. In 2011 a national survey (PeNSE) found that more than half of adolescents aged 13 to 15 had tried alcohol and 9\% reported problems resulting from the use. This behavior can cause permanent harm for the teenagers and others. It is a public health issue that demands for specific alternatives both on treatment and prevention. The BASICS was developed for college students with problematic alcohol use. This intervention is empathetic and flexible, it was designed to help these individuals to make better decisions about alcohol consumption. BASICS is a harm reduction approach that can be classified as a soft technology. Despite its widespread use and advantages to other alternatives, the comprobation of its effectiveness remains a challenge. The aim of this study was to test the effectiveness of BASICS in reducing alcohol abuse in a sample of high school students from public schools in a city of 127,000 São Paulo State-Brazil inhabitants. In this thesis we performed a secondary database analysis of controlled ramdomized trial held throughout the year 2009. Of all students enrolled in public schools, 1712 were younger than 18 years old and agreed to be interviewed. Of these, 1149 were teetotalers, 253 were risky alcohol users and 310 were considered low risk users. Individuals with risk behavior use were drawn to the brief intervention group (IB) or the control group (C). Group C was interviewed only with the assessment tools. IB and C groups were then assessed after 6 and 12 months. There was no statistically significant difference between the means of the AUDIT and AUDITC between groups. We observed consumption reduction in both groups. This decrease can be partially explained by regression to the mean. This reduction did not occur due to attrition: students who left the study were not those with more severe usage patterns. In an attempt to explain these findings we considered the possibilities: the occurrence of Hawthorne effect and the exploratory behavior and erratic pattern of alcohol use by teenagers allows a natural reduction in consumption. It is also noted that a considerable fraction of subjects evolves from a risk consumption to abstinence throughout the study. To better describe this process a Markov model was proposed that included explicitly the exploratory behavior of adolescents and their tendency to abstinence. Through Monte Carlo simulations the model relevant parameters were estimated and we investigated the presence of the Hawthorne effect. Through this analysis we found that there was a reduction in consumption (IB and C) by participation in the research, the alcohol usage pattern was the same in both groups and that consumer distributions can be adequately described by the model. We investigated whether part of this population would have a behavior that indicated a predisposition to a risky pattern of consumption on later stages in life. Through a clustering model fot the time evolution of the AUDIT variable, we noticed that the subjects could be divided into two groups: persistent and non-persistent. Through a statistical analysis using generalized linear models we concluded that adolescent males, who started consuming alcohol earlier, who possessed binging friends and those who came from families with alcohol problems were more likely to participate in the persistent group. We also discussed experimental designs that could be used to further characterize the behavior of adolescents with respect to the alcohol use and to facilitate obtaining the impact of public preventive health policies for this population.

abstract: Programmable metallization cell (PMC) technology employs the mechanisms of metal ion transport in solid electrolytes (SE) and electrochemical redox reactions in order to form metallic electrodeposits. When a positive bias is applied to an anode opposite to a cathode, atoms at the anode are oxidized to ions and dissolve into the SE. Under the influence of the electric field, the ions move to the cathode and become reduced to form the electrodeposits. These electrodeposits are filamentary in nature and persistent, and since they are metallic can alter the physical characteristics of the material on which they are formed. PMCs can be used as next generation memories, radio frequency (RF) switches and physical unclonable functions (PUFs). The morphology of the filaments is impacted by the biasing conditions. Under a relatively high applied electric field, they form as dendritic elements with a low fractal dimension (FD), whereas a low electric field leads to high FD features. Ion depletion effects in the SE due to low ion diffusivity/mobility also influences the morphology by limiting the ion supply into the growing electrodeposit. Ion transport in SE is due to hopping transitions driven by drift and diffusion force. A physical model of ion hopping with Brownian motion has been proposed, in which the ion transitions are random when time window is larger than characteristic time. The random growth process of filaments in PMC adds entropy to the electrodeposition, which leads to random features in the dendritic patterns. Such patterns has extremely high information capacity due to the fractal nature of the electrodeposits. In this project, lateral-growth PMCs were fabricated, whose LRS resistance is less than 10Ω, which can be used as RF switches. Also, an array of radial-growth PMCs was fabricated, on which multiple dendrites, all with different shapes, could be grown simultaneously. Those patterns can be used as secure keys in PUFs and authentication can be performed by optical scanning. A kinetic Monte Carlo (KMC) model is developed to simulate the ion transportation in SE under electric field. The simulation results matched experimental data well that validated the ion hopping model. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2015

The Higgs self-coupling has a vital role by giving a deeper understanding of the Higgs particle. Furthermore, the way it opens to physics beyond the SM, encourages us to do MC simulationstudies for varying λ_hhh . In this project, we investigate the effects of choosing different values for λ_hhh on the kinematics of all particles involved in the hh → τ τ τ τ decay channel and the resultsare compared with what we get from the SM prediction of λ_hhh .The data show that λ_hhh more close to the SM trilinear Higgs self-coupling results in generatingthe Higgs particles with the higher masses and higher momenta. On the other hand, for the moremassive Higgs bosons we have more energetic neutrinos in the final states which escape from thedetector without being detected.

A crise financeira mundial de 2008 associada a fatores intrínsecos adversos afetou fortemente o setor sucroalcooleiro nacional, até então em franca expansão. Ainda que em um momento desfavorável, prevê-se, para um futuro próximo, a retomada dos investimentos no setor, em virtude do aumento da demanda, tanto interna quanto externa, de açúcar e etanol. Nesse contexto, o objetivo do trabalho é avaliar o valor da opção de adiamento, através da análise de opções reais, em projetos de produção de cana-de-açúcar em regiões de grande aptidão à expansão da cultura canavieira: Goiatuba/GO, Maracaju/MS e Uberaba/MG. Os resultados indicam que, sob a ótica da avaliação tradicional de projetos, os três projetos de produção de cana-de-açúcar mostram-se inviáveis, com VPLs de -R$ 4.726.546,86 em Goiatuba/GO, -R$ 3.251.006,50 em Maracaju/MS, enquanto em Uberaba/MG o resultado foi negativo em R$ 3.918.210,03. Através de uma análise de sensibilidade, detecta-se que, para as três regiões, as principais variáveis sujeitas a risco, consideradas no estudo, a afetar o resultado dos projetos são: produtividade, quantidade de ATR e preço de ATR. Essas variáveis são utilizadas para, através da Simulação de Monte Carlo, auferir os desvios-padrão dos retornos dos VPLs de cada projeto, a partir dos quais são calculados os parâmetros para construção de modelo binomial utilizado para valorar a opção de adiamento. Os valores apurados da opção de adiamento para cada região são de R$ 12.774.411,36 para Goiatuba/GO, R$ 2.514.292,71 para Maracaju/MS e R$ 76.086,52 para Uberaba/MG. Quando somados os valores da opção para cada região aos seus respectivos VPLs são apurados os VPLs expandidos: R$ 8.047.864,50 para Goiatuba/GO, R$ -736.713,79 para Maracaju/MS e R$ -3.842.123,50 em Uberaba/MG. Ademais, são definidos os pontos de inflexão das variáveis sujeitas a risco consideradas no trabalho para critério de rejeição dos projetos, tanto na avaliação tradicional de projetos quanto na avaliação a partir das opções reais. Os resultados indicam que a análise de opções reais como critério para rejeição de projetos tende a ser mais maleável em relação às variáveis sujeitas a risco quando comparada à avaliação tradicional de projetos, admitindo menores valores de produtividade, quantidade de ATR e preço do ATR, bem como suportando maiores preços de terra e de custos com corte, carregamento e transporte (CCT) de cana. Não obstante, os VPLs expandidos apontam que o projeto de Goiatuba/GO não deve ser rejeitado, mantendo-se como uma opção de investimento futuro; quanto a Maracaju/MS, a consideração da opção de adiamento na avaliação de projetos não foi suficiente, por si só, para reverter o resultado negativo do VPL tradicional; contudo, pequenos incrementos em variáveis de risco intrínsecas à atividade poderiam tornar o VPL expandido superior a zero, viabilizando o projeto como opção futura de investimento. No caso de Uberaba/MG, o baixo valor da opção de adiamento associado ao já deprimido VPL tradicional leva à rejeição do projeto como opção de investimento futuro. / The global financial crisis in 2008 associated to adverse intrinsic aspects affected significantly the sugarcane sector in Brazil, which was expanding notably until that time. Even though it is in an unfavorable moment, it is forecasted, in a near future, the rebound of investments in the sector, due to the increase of both domestic and international demands for sugar and ethanol. In this scenario, the objective of this study is to evaluate the value of the deferred option, through the analysis of real options, in projects of sugarcane production in regions that have great ability to expand the sugarcane production in Brazil: Goiatuba (Goiás), Maracaju (Mato Grosso do Sul) and Uberaba (Minas Gerais). The results indicate that, regarding the perspective of the traditional evaluation of projects, the three projects of sugarcane production are not viable, with NPVs of -4,726,546.86 reais (Brazilian currency) in Goiatuba (Goiás State), -3,251,006.50 reais in Maracaju (Mato Grosso do Sul State) and - 3,918,210.03 reais in Uberaba (Minas Gerais State). Through a sensitivity analysis, it was discovered that, for the three regions, the major variables subject to risk considered in the study that can affect the results of the projects are: productivity, quantity of TRS (Total Recoverable Sugar) and TRS price. These variables are used to, through the Monte Carlo Simulation, detect the standard deviations of the NPVs\' returns of each project, from which the parameters to construct a binomial model used to value the deferred option are calculated. The values for the deferral option in each region are 12,774,411.36 reais in Goiatuba, 2,514,292.71 reais in Maracaju and 76,086.52 reais in Uberaba. When the option values in each region are added to their respective NPVs, the result is the expanded NPVs: 8,047,864.50 reais in Goiatuba, 736,713.79 reais in Maracaju and -3,842,123.50 reais in Uberaba. Moreover, the inflection points of variables subject to risk considered in the study are defined for both the traditional projects\' evaluation and the evaluation from real options. The results indicate that the analysis of real options as a standard to reject projects tends to be more flexible regarding variables subject to risk when compared to the traditional evaluation of projects, admitting lower values of productivity, TRS amount and TRS price, and accepting higher land prices and costs with cutting, loading and transportation of sugarcane. Nevertheless, expanded NPVs indicate that the project in Goiatuba must not be rejected, continuing as an option of future investment; as for Maracaju, considering the deferred option in the project\'s evaluation was not enough, on its own, to revert the negative result of the traditional NPV; however, slight increases in risk variables intrinsic to the activity could make the expanded NPV higher than zero, enabling the project as a future investment option. Concerning Uberaba, the low value of the deferred option associated to the already reduced traditional NPV takes to the rejection of the project as a future investment option.

Un vaste programme international est en cours pour déterminer les paramètres du phénomène d'oscillation des neutrinos et approfondir la connaissance de la matrice de mélange des neutrinos (MNSP). Le détecteur OPERA, qui est installé dans le laboratoire souterrain du Gran Sasso en Italie, a pour but principal de mettre en évidence l'apparition de neutrinos de type tau dans un faisceau de neutrinos initialement de type muon, produit au CERN (CNGS) 730 km en amont. Il est aussi en mesure de détecter les oscillations des neutrinos muon en neutrinos électron, donnant accès au paramètre de mélange sin(2θ13)2, où θ13 est le dernier angle de la matrice MNSP finalement déterminé en 2012 conjointement par Daya Bay, RENO et Double Chooz. Pour déterminer la présence des ντ dans le faisceau, le détecteur OPERA est composé de cibles calorimétriques utilisant une alternance de plaques de plomb et de films d'émulsion. Ceux-ci permettront de reconstruire les traces des particules chargées résultant des interactions neutrino avec une précision inégalable (de l'ordre du micron). La recherche des événements de signal d'oscillation νµ → νe sera basée sur l'aptitude à identifier les électrons, à rejeter les événements de fond où un π0 est produit et à soustraire le fond dominant intrinsèque provenant du faisceau. Ce travail de thèse a pour objectif l'élaboration de méthodes d'analyse pour améliorer les performances du détecteur OPERA dans la recherche d'oscillations νµ → νe . / An international program is ongoing to measure the neutrino oscillation phenomenon and to determine the neutrino mixing matrix (MNSP) parameters. OPERA is a long-baseline neutrino experiment located at the Gran Sasso Laboratory in Italy, 730~km from CERN, downstream in the CNGS neutrino beam. The OPERA experiment is designed and optimised for a direct appearance search of νµ → ντ oscillations. It can also detect the νµ → νe oscillation driven by sin(2θ13)2 , where θ13 is the last mixing angle finally measured by the Daya Bay, RENO, and Double Chooz experiments in 2012. To observe the presence of ντ interactions in the beam, the OPERA detector is composed of calorimetric targets made of a modular structure called the "brick": a sandwich of lead plates interspaced with emulsion layers. The latter allows reconstructing tracks of charged particles produced in the neutrino interactions with a micrometric resolution. The search for the νµ → νe oscillation signal is based on the capability of identifying the electrons, rejecting background events where neutral pions are produced and keeping under control the intrinsic and dominant background source from the beam contamination. This work aims to elaborate analysis methods to improve the OPERA detector performance in the νµ → νe oscillation search.

La compétition des interactions est une caractéristique essentielle des systèmes frustrés, elle est à l'origine d'une large dégénérescence des états fondamentaux classiques ou, obtenus par une théorie de champ moyen.Fréquemment la dégénérescence peut être levée par des fluctuations thermiques ou quantiques, ce qui constitue la base du mécanisme appelé textit{ordre par le désordre}.Les systèmes magnétiques étudiés expérimentalement contiennent une quantité inévitable de désordre structural.Dans cette thèse de doctorat, l'influence des défauts, créé par des sites inoccupés ou par un désordre des liens sur l'espace dégénéré des états fondamentaux est étudiée pour des systèmes frustrés divers.Nous avons trouvé qu'un désordre structural est, lui aussi, capable de lever systématiquement la dégénérescence; par ailleurs, la tendance est inverse par rapport au le mécanisme d'ordre par le désordre produit par les fluctuations.Pour chacun des modèles considérés, les corrections à l'énergie ont été calculées sous la forme de termes anisotropes effectifs qui agissent sur l'espace dégénéré des états fondamentaux.Ces arguments analytiques ont été confirmés par des calculs numériques que nous avons effectués par minimisation de l'énergie, ainsi que par simulation de type Monte-Carlo classique. La séquence des états ordonnés que nous avons détectée est attribuée à la compétition entre l'effet d'ordre induit par les fluctuations et celui induit par les défauts structuraux. L'effet observé peut ouvrir des possibilités supplémentaires de contrôler la structure magnétique des systèmes.Enfin, les effets d'un champ magnétique externe ont été étudiés pour le système antiferromagnétique pyrochlore pur avec anisotropie de plan facile.Nous avons observé des transitions de phases qui dépendent de l'orientation du champ et qui n'existent pas dans la description de type champ moyen du système. Elles constituent une généralisation des transitions de type spin-flop pour le cas de la symétrie discrète $mathbb{Z}_k$ brisée avec $k > 2$. / Competing interactions is an essential feature of frustrated systems, they stand behind the large degeneracy of classical or mean-field ground states.%produce degeneracy of classical mean-field ground states.In many cases the degeneracy can be lifted by thermal and quantum fluctuations, such mechanism is commonly called textit{order from disorder}.Experimentally studied magnetic systems inevitably contain a finite amount of structural disorder.In this work the influence of defects, namely vacancies and bond disorder, on a degenerate ground state manifold is studied for various frustrated systems.We find that quenched disorder is also capable of consistently lifting the degeneracy, moreover, it has%in a wide range of frustrated systems.%Moreover, the effect of quenched disorder leads toan opposite tendency, compared to the order by disorder mechanism, produced by fluctuations.For every considered model, analytic energy corrections are derived in the form of effective anisotropic terms, which act on the manifold of degenerate ground states.Analytical arguments are confirmed by numerical calculations, which include energy minimization and classical Monte Carlo simulations.The detected sequences of ordered states is attributed to competition of fluctuations and structural disorder.The observed effect can open additional possibilities in tuning magnetic structure of the system.Finally, the effect of external magnetic field is investigated for the pure $XY$ pyrochlore antiferromagnet.Depending on the field orientation we observe phase transitions, which do not exist within the mean-field description of the system.They are generalizations of the spin-flop transition for the case of broken discrete $mathbb{Z}_k$ symmetry with $k > 2$.

La Radiothérapie Conformationnelle avec Modulation d'Intensité (RCMI), aussi dénommée IMRT, est une technique avancée de radiothérapie de haute précision qui repose sur l'utilisation d'un collimateur multi-lames, placé en sortie de l'accélérateur, dont les lames vont se déplacer pendant la séance d'irradiation afin de produire un faisceau d'intensité modulée, adaptée à la forme des structures anatomiques du patient. Un tel dispositif permet d'obtenir une répartition de dose homogène dans le volume cible et d'épargner au mieux les tissus sains environnants1, ouvrant la voie à l'escalade de dose et donc à l'amélioration des résultats thérapeutiques. Néanmoins, la mise en œuvre d'une telle technique nécessite la réalisation d'un contrôle du système de délivrance de la dose de manière à s'assurer que la fluence délivrée par l'appareil de traitement est bien conforme à la fluence attendue. / Intensity Modulated Radiotherapy (IMRT) is a high-precision radiotherapy technique based on the use of a multi-leaf collimator, placed at the output of the accelerator. The modulation is adapted to the patient's anatomical structures and obtained by leaves movement during the beam administration. To ensure that the delivered fluence is consistent with the expected one, a control is necessary. In clinical routine, this control isn't achieved on the patient, but on a phantom, before the beginning of the treatment New emerging solutions make possible an online control, done during the treatment of the patient. They can be divided into three classes: those which use data acquired by the accelerator, those which exploit the portal imager and those which use a dedicated detector placed at the exit of the head of the accelerator, upstream of the patient. The thesis work presented here relate to the development of a detector of this third class, Tradera (Transparent Detector for Radiotherapy). The choice was made to use a segmented plane ionization chamber.The first phase of the project was to design the detector thanks to studies made by Monte Carlo simulations. For this it was necessary to model the photon beam. The choice of a point source of photons, quick to set up, has been retained. The characteristics of the particles at the detector input obtained with our model were compared with those obtained with a more complex model: a phase space obtained from the database of the IAEA. Once the model validated, Geant4 code was used to size the various elements of our detector. A innovative geometry has been proposed. It consists in introducing material in the sensitive volume of the detector to limit the lateral travel of the electrons from the interaction of photons, and thus improve the spatial resolution of the detector. In practice, a checkerboard with plastic pads is introduced in the sensitive volume. The benefit of this solution has been shown by simulations.The second phase was to assess a prototype in a clinical beam with radiation equipment and test the performance of various associated acquisition electronics. For a long time, reading was made at the output of a single channel at a time. First, a picoammeter was used to measure the average output current. Then the ionization current has been studied at the time scale of a pulse of the beam, allowing the development of a charge preamplifier dedicated to our application. This charge preamplifier permit to know, for a single beam pulse, the electrical charge measured by one channel of the prototype with a uncertainty of 5%, and thus makes it possible to study the evolution of the charge pulse as a function of irradiation time. Once the choice of this readout electronics was validated, the charge preamplifier was realized in small series : the acquisition in multi-channels on an area of ​​3 cm square was possible. The first beam images could then be obtained for static and dynamic beam.