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Dans cette thèse, nous nous intéressons aux problèmes d'ordonnancement simultané de tâches et de périodes d'indisponibilité. Dans un premier temps, nous réalisons une revue de littérature sur la prise en compte des indisponibilités dans les problèmes d'ordonnancement.Ensuite, nous définissons un modèle général qui englobe des modèles existants de la littérature pour des ateliers à une machine et à machines parallèles. Une approche globale de résolution basée sur les problèmes d'affectation linéaire a été développée. Cette approche permet de résoudre le modèle général comme un simple problème d'affectation. Un grand nombre de critères d'optimisation et de modèles de maintenance peuvent être traités en utilisant cette approche, fournissant ainsi l'accès à tous les modèles qui ont souvent été étudiés séparément dans la littérature. Les résultats élaborés avec cette approche ont permis de résoudre des problèmes d'ordonnancement non traités avant et aussi de généraliser et améliorer des résultats antérieurs.Nous proposons, en dernier lieu, une étude d'un problème flow shop à deux machines en présence d'une période d'indisponibilité sur la deuxième machine. Une étude de complexité est menée sur le problème. Ensuite, nous définissons des propriétés d'optimalité. En se basant sur ces propriétés, trois méthodes de résolution exacte sont proposées; une méthode énumérative, un programme linéaire et une méthode basée sur l'approche de séparation et évaluation B&B. Une analyse expérimentale est présentée afin d'évaluer les performances de ces méthodes. / In classical scheduling problems, machines are assumed to be continuously available. However, in a real manufacturing system, machine may become unavailable during the scheduling period due to preventive maintenance. In this dissertation, we are interested in the problems of jointly scheduling jobs and unavailability periods.We start our study by introducing a general framework for scheduling problems and we present a review of the scheduling problems with unavailability periods.Then, we consider a general model for scheduling jobs on single-machine and unrelated parallel-machines with maintenance interventions. A unified approach is presented to solve this model as an assignment problem. A large number of performance criteria and maintenance models can be treated in this way, thus providing access to models that have often been studied separately in the published literature.Finally, we focus on the problem of a two-machine flow-shop makespan scheduling with the deteriorating maintenance period on the second machine. Then, we establish some conditions of the optimal schedule. In order to solve the problem, we proposed different exact methods: enumerative method, mixed-integer programming (MIP) model and a branch & bound algorithm. Numerical experiments are reported for all the proposed methods.

In a world with an increasing flow of written information online and offline, the demand for automatic translation, simplification and summarization technology is growing. The tool StilLett uses several lexical and semantic rules to automatically simplify text, shortening the time from original text to simplified text compared to manual simplification. Four of the simplification types were evaluated in this study, using three different eye tracking measures; total dwell time, number of regressions, and average fixation duration. No statistically significant differences were found for any of the simplification types when compared to the corresponding original sentences, indicating that for this population the difficulty of the sentences was roughly the same.

[pt] O método da freqüência e a duração, construído a partir das técnicas de Markov, é uma ferramenta extremamente útil na avaliação da confiabilidade de sistemas de potência , por permitir a obtenção da probabilidade, freqüência e duração média de falha no suprimento de potência para uma configuração planejada do sistema. Neste trabalho, o método da freqüência e duração é ampliado de modo a modelar de forma precisa os diversos estados operativos das unidades geradoras, simultaneamente com os diversos níveis de carga admissíveis para um período típico, obtendo-se assim índices mais realísticos para a confiabilidade da capacidade de geração. Um algoritmo eficiente para a construção dos modelos de geração e reserva é desenvolvido a partir de técnicas de convolução discreta e de padronização de estados, as quais viabilizam a avaliação dos índices de freqüência e duração para sistemas de grande porte. O algoritmo proposto é aplicado a vários sistemas de geração, incluindo o Sistema Teste de Confiabilidade do IEEE e uma configuração do sistema Sul/Sudeste brasileiro planejada para o ano de 1991. / [en] The frequency and duration method, built from Markov techniques, is a extremely useful tool in power system reliability evaluation, since it allows the calculation of probability, frequency and average duration of power supply failures for a planned system configuration. In this work, the frequency and duration method is generalized in order to model accurately the existing derated state of generating units, simultaneouly with all possible load levels for a given period, so that more realistic generating capacity indices are obtained. An efficient algorithm for building the generation and risk models is developed from discrete convolution and state rounding techniques which make possible the evaluation of frequency and duration indices for large power generating systems. The proposed algorithm is applied to typical generating systems, including the IEEE Reliability Test System, and also the Brazilian South/Southeast generating system planned for 1991.

Tarefas: uma estratégia para criação de performances é uma pesquisa em poéticas visuais que teve origem no processo de criação de Figuras e Fantasmas e nos desdobramentos que as apresentações públicas desta performance produziram. A investigação teórica e prática desenvolvida para performance Figuras e Fantasmas conduziu este estudo à noção de tarefa, um processo de trabalho criado por Anna Halprin, no final dos anos 1950. Estudamos a tarefa em termos processuais e conceituais e, a partir desse referencial teórico, analisamos os meios pelos quais podemos empregar contemporaneamente um procedimento que espelha uma época na qual a simbiose entre arte e vida somada ao papel do artista estavam em questão. Nossa investigação propõe um recorte que elegeu a não-atuação, atuação, repetição e duração como elementos estruturais das tarefas. Constatamos que esses elementos dosados e articulados permitem que noção original de tarefa possa ser atualizada. / Tasks: an strategy to the creation of performances is a research in Visual Poetics that was originated with the process of creation of Figuras e Fantasmas and the results that unfolded from its public presentations. The theoretical and practical investigations developed for the performance Figuras e Fantasmas directed this study to the notion of task, that was a process of work created by Anna Halprin in the end of the 1950s. From these theoretical references, the task was studied in processual and conceptual terms and there was made an analysis of the means through which, contemporaneosly, we could use a procedure mirroring a period when the symbiosis between art and life in conjunction with the role of the artist were in question. In this investigation, the not-acting, acting, repetition and duration were chosen as structural elements of the tasks. It was verified that these elements - measured and articulated - allow the original notion of task to be updated.

Submitted by Cristiane Shirayama (cristiane.shirayama@fgv.br) on 2011-05-23T19:19:17Z No. of bitstreams: 1 61090100002.pdf: 359665 bytes, checksum: 87fb6b40a526393956abe85cb90545fb (MD5) / Approved for entry into archive by Gisele Isaura Hannickel(gisele.hannickel@fgv.br) on 2011-05-23T19:31:24Z (GMT) No. of bitstreams: 1 61090100002.pdf: 359665 bytes, checksum: 87fb6b40a526393956abe85cb90545fb (MD5) / Approved for entry into archive by Gisele Isaura Hannickel(gisele.hannickel@fgv.br) on 2011-05-23T19:33:27Z (GMT) No. of bitstreams: 1 61090100002.pdf: 359665 bytes, checksum: 87fb6b40a526393956abe85cb90545fb (MD5) / Made available in DSpace on 2011-05-24T11:16:21Z (GMT). No. of bitstreams: 1 61090100002.pdf: 359665 bytes, checksum: 87fb6b40a526393956abe85cb90545fb (MD5) Previous issue date: 2011-02-09 / Este trabalho teve como objetivo identificar o impacto do risco de liquidez nos retornos excedentes esperados das debêntures no mercado secundário brasileiro. Foram realizadas análises de regressão em painel desbalanceado com dados semestrais de 101 debêntures ao longo de oito semestres (primeiro semestre de 2006 ao segundo semestre de 2009), totalizando 382 observações. Sete proxies (Spread de Compra e Venda, %Zero Returns, Idade, Volume de Emissão, Valor Nominal de Emissão, Quantidade Emitida e %Tempo) foram utilizadas para testar o impacto do risco de liquidez nos yield spreads das debêntures. O yield spread foi controlado por até dez outras variáveis determinantes que não a liquidez (Fator Juros, Fator Crédito, Taxa Livre de Risco, Rating, Duration, quatro variáveis contábeis e Volatilidade de equity). A hipótese nula de que não há prêmio de liquidez para o mercado secundário de debêntures no Brasil foi rejeitada apenas para três das sete proxies (Spread de Compra e Venda, Valor Nominal de Emissão e Quantidade Emitida). Os prêmios encontrados são bastante baixos (1,9 basis point para cada 100 basis point de incremento no Spread de Compra e Venda, 0,5 basis point para um aumento de 1% no valor do Valor Nominal de Emissão e 0,17 basis point para cada menos 1000 debêntures emitidas), o que vai ao encontro dos resultados encontrados por Gonçalves e Sheng (2010). De qualquer forma houve perda da eficiência das proxies de liquidez após correção das autocorrelaçôes e potenciais endogeneidades, seja através da inclusão de efeitos fixos, da análise em primeiras diferenças ou da utilização de um sistema de três equações.

This study aims to investigate the developmental ability of beginning and advance L1 English learners of Arabic to pronounce standard Arabic geminate consonants when enrolled in a full time L2 program. The results showed that English learners produced shorter closure duration when pronouncing geminates. In particular, the beginners lengthened singletons more than the advanced learners did, while both groups of learners shortened geminates much more so than native speakers of Arabic. The advanced L1 English learners of Arabic produced longer geminate duration than beginners. The ultimate result was a smaller ratio between singleton and geminate consonants in comparison to native speakers of Arabic.

This study examines empirically the transition, persistence, and loan demand in the rural credit market using panel data. The data was collected for seven rounds (1994-2009) from 15 villages in Ethiopia. The sample size is about 1500 households for each round. . Chapter one examines the determinants of simultaneous borrowing and lending. We also investigate why some households in rural Ethiopia simultaneously borrow and lend. Who are these households? Panel logit model is estimated for the sub-sample of borrowers and lenders. The result suggests that households that simultaneously borrows and lends are relatively better-off households. The probability of being a simultaneous borrower and lender is higher for households with strong village level networks. Moreover, households that are affected by common shock are more likely to be a simultaneous borrower and lender. Chapter two examines the dynamics and persistence in the rural credit markets in Ethiopia. It also examines the determinants of dynamics and persistence in borrowing and lending. Duration, dynamic probit, and dynamic multinomial logit models are estimated. We control for unobserved heterogeneity and initial condition. The result reveals the existence of positive duration dependence in both only borrowing households and simultaneously lending and borrowing households. The longer the duration as a borrower, the more likely to exit from borrowing. The longer the duration out of borrowing, the more likely to re-enter to borrowing. Off-farm work, fertilizer use, household size, and storing crop are an important determinant of the probability of exit from borrowing. There is also true state dependence in lending, borrowing, and simultaneously borrowing and lending households. This means the probability of being a borrower in the current period is highly correlated with being in the same state in the previous period. Poverty status, flood, labor sharing, membership in mutual help association, total oxen owned, storing crop, off-farm activities, and fertilizer use are an important determinant of the probability of being a borrower. Chapter three examines the determinants of demand for credit in rural Ethiopia. Bias due to data truncation, variation of the interest rate, and using loan data from a single source are the challenges in estimating demand for credit in the context of rural credit market. This study captures data truncation by estimating a panel Tobit model. The variation in the interest rate is also controlled by using village dummies and their interaction with the source of the loan. Total loan obtained from multiple sources is used as a dependent variable. The result reveals that initial endowment proxied by the value of assets, household size, the age of the head of the households, transitory income, and real per capita consumption are the most important determinants of demand for credit.

La pomme, fruit le plus cultivé sur le sol français, est principalement menacée par le pathogène Venturia inaequalis, responsable de la maladie de la tavelure qui génère des pertes considérables si elle n'est pas traitée. La politique actuelle de gestions des risques phytopathologiques en France incite à une forte réduction des traitements phytosanitaires tout en maximisant le rendement et la qualité des productions. Dans ce contexte, il apparaît indispensable de mieux comprendre les interactions entre l'arbre, son pathogène, et leur environnement, qui s'articulent pour le cas de la tavelure du pommier autour de la durée d'humectation des feuilles. Au cours de ce travail nous nous sommes intéressés à ce paramètre pour essayer de mieux comprendre les interactions entre microclimat de l'arbre et durée d'humectation. L'étude s'est déroulée en trois étapes majeures : la modélisation de l'évaporation d'une goutte sur un support végétal, l'étude expérimentale de la mouillabilité des feuilles de pommier, et l'étude expérimentale de la variabilité spatiale de la durée d'humectation sous un couvert de pommiers. Ce travail a permis d’expliciter la forte variabilité intra-couronne de la durée d'humectation via la prise en compte de la structure de l’arbre et de la dynamique horaire du microclimat. Le modèle développé, au delà des liens déjà connus entre l’intensité du flux évaporatif et les variables climatiques, a montré la sensibilité importante du temps d’évaporation à la mouillabilité du support via la forme de la goutte d’eau, mettant en avant la nécessité de quantifier au mieux cette interaction goutte support via l’estimation des angles de contact statiques et dynamiques. / Apples, which are the most cultivated fruit in France, are mainly endangered by the fungal pathogen Venturia inaequalis that cause apple scab disease on apple. This disease can be responsible of major products loss unless orchards are treated against apple scab. Nowadays in France, the phytopathological diseases management policies are encouraging growers to reduce considerably the use of pesticides, while keeping a high quality and yield level. In this context, one must understand better how the plant, the pathogen and their environment, interact with each other: for apple scab, the most important environmental parameter is leaf wetness duration. During this work, we studied leaf wetness duration to understand the interactions that occur between the tree microclimate and the wetness duration. To do that we divided our work in three major steps : the modeling of evaporation of a droplet at rest on a leaf, the experimental study of apple leaves wettability, and the experimental study of wetness duration spatial variability within an apple trees orchard. This study led us to clarify the strong intra-crown variability of leaf wetness duration through the consideration of tree structure and hourly dynamics of microclimate. The model we developed, beyond the known links between the evaporative flux intensity and the climatic parameters, showed a strong sensibility of the evaporation duration to the substrate wettability, highlighting the necessity to quantify at best this interaction, through the estimation of static and dynamic contact angles.

Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro / A presente dissertação trata da relação entre o conceito de tempo tal como foi pensado pelo filósofo francês Henri Bergson (1859-1941) e pelo físico alemão Albert Einstein (1879-1955). Ambos foram contemporâneos e tiveram a chance de confrontar suas opiniões discordantes sobre a natureza do tempo. Em seu polêmico ensaio Duração e Simultaneidade (1922), Bergson expôs sua teoria sobre tempo, pensado enquanto duração, já levando em conta a teoria da relatividade de Einstein. O objetivo presente aqui é explicitar os conceitos de tempo em ambos os autores e relacioná-los, considerando os pontos críticos do ensaio de Bergson sobre a relatividade de Einstein. Para tanto, esse trabalho foi dividido em três partes: a primeira trata da teoria da duração de Bergson em seu pensamento filosófico; a segunda aborda a teoria da relatividade de Einstein a partir da evolução do pensamento físico sob o ponto de vista do movimento; e a terceira e última trata do embate de ambas as teses contidas em Duração e Simultaneidade. As principais conclusões obtidas são: (1) Bergson cometeu um erro em seu ensaio ao tentar transpor sua avaliação sobre a teoria da relatividade especial para a teoria da relatividade geral de Einstein; (2) tal erro não desfaz a tese de Bergson sobre a fundamentalidade da duração em relação ao tempo físico; (3) em sua tentativa de apontar a essencialidade de um tempo puro com respeito a um tempo espacializado, Bergson esbarra nos limites da linguagem conceitual que ele mesmo havia compreendido e denunciado em toda sua obra; (4) e ainda assim, permanece a força do pensamento da duração bergsoniano, cujo alcance é tão pouco considerado pela ciência de seu tempo, como pela ciência de hoje. Tal como proposto por Bergson, essas conclusões apontam para a possibilidade de um trabalho complementar entre filosofia e ciência a partir de uma melhor compreensão de seus respectivos trabalhos. Ademais, em tal trabalho cooperativo, intui-se a possibilidade de enxergar a realidade do devir-extensivo do universo para além do amálgama espaço-temporal. / This dissertation deals with the relation between the concepts of time as it was thought by the French philosopher Henri Bergson (1859-1941) and by the German physician Albert Einstein (1879-1955). Both of them were contemporary and had the chance to face their unequaled opinions about nature of time. In his polemic assay Duration and Simultaneity (1922), Bergson exposed his theory about time, thought it as duration, already regarding Einsteins relativity theory. The objective here present is to make clear both authors concepts of time and relate them considering the critical points contained in the Bergsons assay about the relativity of Einstein. Thus, this work was divided in three parts: the first one treats with the duration theory of Bergson in his philosophical thought; the second one considers the relativity theory of Einstein taking as start point the historic evolution of the physician thought in his aspect with the analysis of the movement; and the third and last one struggles to take care of the conflict between both thesis as it appears in Duration and Simultaneity. The main conclusions extracts are: (1) Bergson made a mistake in his assay as he tries to transpose the consequences from his analysis about the especial relativity theory to the general relativity theory of Einstein; (2) this mistake doesnt undo the Bergsons thesis about the fundamentality of the duration in its relation with the physician time; (3) in his trial to indicate the essentiality of one pure time in its respect with a spatialized time, Bergson dashes with the limits of the conceptual language which himself had comprehend and denounced all along of his work; (4) and even so, remains the strength of the bergsonian thought about duration whose reach is so far of being considered by the science of his time as so far as it is by science today. As it was proposed by Bergson, those conclusions indicate the possibility to establish a complementary work between philosophy and science since it has a better comprehension of their respective works. Besides, in this cooperative work, is given an intuition to the possibility to see the reality of the universes extensive becoming to beyond of the space-time amalgam.