Les cours d’eau et leurs bassins versants sont des systèmes complexes et en équilibre dynamique. Si l’on connait qualitativement assez bien la plupart des processus dont ils sont le siège (ex. transport de matière organique et de sédiments, transformation des litières, etc…), il est beaucoup plus difficile d’en avoir une représentation pertinente à la bonne maille compte tenu de l’emboitement d’échelles des processus, des déterminants terrestres agissant sur les milieux aquatiques et surtout des différents facteurs de stress qui s’y combinent. Nous avons mené une exploration dont le but était de rechercher les causes souvent multiples de dégradation de l’état écologique, d’en connaître l’étendue spatiale et la gravité, pour être en mesure de recommander des actions efficaces de restauration. Dans la première partie de cette thèse, nous avons développé des modèles explicatifs de l’état écologique à large échelle capables de donner des réponses applicables aux échelles de décision et de gestion, à savoir européenne, nationale et régionale avec comme objectif principal de comparer les relations entre les pressions combinées représentées par l’occupation du sol et l'état écologique des cours d’eau de quatre pays européens: la France, la Slovaquie, l'Estonie, et le Royaume-Uni (Angleterre et Pays de Galles). Cette étude a permis (i) d’établir une hiérarchie des catégories d’occupation du sol influant sur l'état écologique, en particulier l'agriculture et l'urbanisation, (ii) d’identifier des tendances régionales dans ces relations pression-impact et (iii) d’évaluer le poids relatif de la pression à l‘échelle du bassin et du corridor rivulaire, et l’effet tampon des zones rivulaires suivant la nature de leur couverture. Dans une deuxième partie, nous avons construit un corpus de modèles capables d’expliquer d’une part la variabilité des indices biologiques utilisés dans les réseaux et de prédire d’autre part l’état écologique des masses d’eau françaises non suivies par le réseau de contrôle et de surveillance (RCS). Cette étude a permis de montrer que : (i) le facteur le plus impactant pour l’état biologique qu’il soit mesuré à partir des macroinvertébrés, des poissons ou des diatomées était la physico-chimie, suivie de l’occupation du sol et de l’hydromorphologie et (ii) l’utilisation de ces trois types de pressions permettait de développer des modèles prédictifs de l’état biologique robustes et fiables. Dans une troisième partie, nous avons voulu tester si les relations entre les pressions à l'échelle locale et l'état écologique étaient hiérarchiquement influencées par la typologie régionale (basée sur les caractéristiques géographiques naturelles et les forces motrices). Ceci nous a permis de montrer que la prise en compte d’une typologie basée sur les forces motrices des bassins versants ne remettait pas en cause la hiérarchie des effets des pressions sur la biologie. Enfin, dans une quatrième et dernière partie, nous avons développé une approche nouvelle qui propose de prendre en compte les connaissances sur l’organisation des échelles et sur les liens entre pressions et état écologique, en construisant et en analysant un modèle structurel qui a permis de relier entre elles des variables latentes correspondant aux pressions d’occupation du sol, hydromorphologiques et physico-chimiques et d’analyser in fine leur effet sur l’état écologique mesuré ici à travers l’I2M2. Le développement de ce modèle a montré : (i) l’effet important de l’occupation du sol sur l’hydromorphologie et sur la physico-chimie et l’effet indirect qui en découle sur les macroinvertébrés, (ii) l’effet de l’hydromorphologie sur la mosaïque de substrats, la dynamique des nutriments et de la matière organique, impliquant un effet indirect majeur sur les macroinvertébrés / The rivers and their watersheds are complex systems in dynamic balance. If processes acting in stream are relatively well known (organic matter and sediment transport, litter degradation, etc ...), it is much more difficult to have a relevant representation of this functioning considering the hierarchy of scales, land determinants affecting aquatic environments and combined multiple stressors. We conducted an exploration whose purpose was to seek the multiple causes of degradation of the ecological status, to know the spatial extent and severity and to be able to recommend effective restoration actions. In the first part of the thesis, we developed large-scale models, based on existing data, to give answers applicable to the decision and management scales, i.e. European, national and regional. The main was to compare the relationships between the combined pressures represented by land cover and the ecological status of running waters in four European countries: France, Slovakia, Estonia, and UK (England and Wales). This first study allowed us i) to establish the hierarchy of the major influences that impact ecological status, particularly agriculture and urbanisation, ii) to identify regional patterns in these pressure-impact relationships and iii) to evaluate the relative weight of the pressures acting at the basin and riparian corridor scales, and the possible buffering effect of riparian land cover. In the second part of the thesis, we built a corpus of models capable of explaining the variability of the biological indices used in the survey network and also predict the ecological status of non-monitored water bodies in France. This permits to demonstrate that : (i) the parameters characterizing the load of nutrients and organic matter had a predominant effect on the three compartments, followed by land use and hydromorphology, (ii) it is possible to build models capable of predicting ecological status that are efficient and easily transferable, using data of different scales that influence the functioning of hydrosystems. In the third part, we tested if the relationships between local scale pressures and ecological status are hierarchically influenced by regional patterns (such as natural physiographic and/or driving forces). Introducing hierarchical factors in multi-stress models can lead to slight variations in responses of organisms to pressures according to their natural characteristics and their driving forces acting at catchment scale. And in the last part, the purpose of our approach was to take into account the nested scale organisation and the links between anthropogenic pressures and river ecological status by building - and analysing the results of - a model based on the PLS path modelling method. This method can be used to simultaneously analyse the effects of latent variables corresponding to land-use, hydromorphological and physico-chemical pressures on the ecological status of rivers, synthetically measured in this study by the macroinvertebrate-based French biotic index for wadeable rivers (I2M2). The development of this model should allow us to demonstrate : (i) the importance of land use effect exerted on both hydromorphology and physico-chemistry and their translation as an indirect effect on biological condition of streams, (ii) that hydromorphological alterations had an effect on substrates structure and nutrients and organic matter concentrations implying that hydromorphology has a major indirect effect on macroinverteb

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Both traffic congestion and road accidents impose a burden on society, and it is therefore important for transport policy makers to reduce their impact. An ideal scenario would be that traffic congestion and accidents are reduced simultaneously, however, this may not be possible since it has been speculated that increased traffic congestion may be beneficial in terms of road safety. This is based on the premise that there would be fewer fatal accidents and the accidents that occurred would tend to be less severe due to the low average speed when congestion is present. If this is confirmed then it poses a potential dilemma for transport policy makers: the benefit of reducing congestion might be off-set by more severe accidents. It is therefore important to fully understand the relationship between traffic congestion and road accidents while controlling for other factors affecting road traffic accidents. The relationship between traffic congestion and road accidents appears to be an under researched area. Previous studies often lack a suitable congestion measurement and an appropriate econometric model using real-world data. This thesis aims to explore the relationship between traffic congestion and road accidents by using an econometric and GIS approach. The analysis is based on the data from the M25 motorway and its surrounding major roads for the period 2003-2007. A series of econometric models have been employed to investigate the effect of traffic congestion on both accident frequency (such as classical Negative Binomial and Bayesian spatial models) and accident severity (such as ordered logit and mixed logit models). The Bayesian spatial model and the mixed logit model are the best models estimated for accident frequency and accident severity analyses respectively. The model estimation results suggest that traffic congestion is positively associated with the frequency of fatal and serious injury accidents and negatively (i.e. inversely) associated with the severity of accidents that have occurred. Traffic congestion is found to have little impact on the frequency of slight injury accidents. Other contributing factors have also been controlled for and produced results consistent with previous studies. It is concluded that traffic congestion overall has a negative impact on road safety. This may be partially due to higher speed variance among vehicles within and between lanes and erratic driving behaviour in the presence of congestion. The results indicate that mobility and safety can be improved simultaneously, and therefore there is significant additional benefit of reducing traffic congestion in terms of road safety. Several policy implications have been identified in order to optimise the traffic flow and improve driving behaviour, which would be beneficial to both congestion and accident reduction. This includes: reinforcing electronic warning signs and the Active Traffic Management, enforcing average speed on a stretch of a roadway and introducing minimum speed limits in the UK. This thesis contributes to knowledge in terms of the relationship between traffic congestion and road accidents, showing that mobility and safety can be improved simultaneously. A new hypothesis is proposed that traffic congestion on major roads may increase the occurrence of serious injury accidents. This thesis also proposes a new map-matching technique so as to assign accidents to the correct road segments, and shows how a two-stage modelling process which combines both accident frequency and severity models can be used in site ranking with the objective of identifying hazardous accident hotspots for further safety examination and treatment.

In risk analysis, Benchmark dose (BMD)methodology is used to quantify the risk associated with exposure to stressors such as environmental chemicals. It consists of fitting a mathematical model to the exposure data and the BMD is the dose expected to result in a pre-specified response or benchmark response (BMR). Most available exposure data are from single chemical exposure, but living objects are exposed to multiple sources of hazards. Furthermore, in some studies, researchers may observe multiple endpoints on one subject. Statistical approaches to address multiple endpoints problem can be partitioned into a dimension reduction group and a dimension preservative group. Composite scores using desirability function is used, as a dimension reduction method, to evaluate neurotoxicity effects of a mixture of five organophosphate pesticides (OP) at a fixed mixing ratio ray, and five endpoints were observed. Then, a Bayesian hierarchical model approach, as a single unifying dimension preservative method is introduced to evaluate the risk associated with the exposure to mixtures chemicals. At a pre-specied vector of BMR of interest, the method estimates a tolerable area referred to as benchmark dose tolerable area (BMDTA) in multidimensional Euclidean plan. Endpoints defining the BMDTA are determined and model uncertainty and model selection problems are addressed by using the Bayesian Model Averaging (BMA) method.

Nous présentons une nouvelle méthode pour étudier les relations entre la structure génétique des populations et l'environnement. Cette méthode repose sur des modèles hiérarchiques bayésiens qui utilisent conjointement des données génétiques multi-locus et des données spatiales, environnementales et/ou culturelles. Elle permet d'estimer la structure génétique des populations, d'évaluer ses liens avec des covariables non génétiques, et de projeter la structure génétique des populations en fonction de ces covariables. Dans un premier temps, nous avons appliqué notre approche à des données de génétique humaine pour évaluer le rôle de la géographie et des langages dans la structure génétique des populations amérindiennes. Dans un deuxième temps, nous avons étudié la structure génétique des populations pour 20 espèces de plantes alpines et nous avons projeté les modifications intra spécifiques qui pourront être causées par le réchauffement climatique. / We introduce a new method to study the relationships between population genetic structure and environment. This method is based on Bayesian hierarchical models which use both multi-loci genetic data, and spatial, environmental, and/or cultural data. Our method provides the inference of population genetic structure, the evaluation of the relationships between the structure and non-genetic covariates, and the prediction of population genetic structure based on these covariates. We present two applications of our Bayesian method. First, we used human genetic data to evaluate the role of geography and languages in shaping Native American population structure. Second, we studied the population genetic structure of 20 Alpine plant species and we forecasted intra-specific changes in response to global warming. STAR

Para analisar dados binários oriundos de uma estrutura hierárquica com dois níveis (por exemplo, aluno e escola), uma alternativa bastante utilizada é a suposição da distribuição binomial para as unidades experimentais do primeiro nível (aluno) condicionalmente a um efeito aleatório proveniente de uma distribuição normal para as unidades do segundo nível (escola). Neste trabalho, propõe-se a adição de um efeito aleatório normal no primeiro nível de um modelo linear generalizado hierárquico binomial para contemplar uma possível variabilidade extra-binomial decorrente da dependência entre os ensaios de Bernoulli de um mesmo indivíduo. Obtém-se o processo de estimação por máxima verossimilhança para este modelo a partir da verossimilhança marginal dos dados, após uma dupla aplicação do método de quadratura de Gauss-Hermite adaptativa como aproximação para as integrais dos efeitos aleatórios. Realiza-se um estudo de simulação para contrastar propriedades inferenciais do modelo aspirante com o modelo linear generalizado binomial, um modelo de quase-verossimilhança e o tradicional modelo linear generalizado hierárquico em dois níveis. / A common alternative when analyzing binary data originated from a two-level hierarchical structure (for instance, student and school) is to assume a binomial distribution for the experimental units of the first level (student) conditionally to a normal random effect for the second level units (school). In this work, we propose the inclusion of a second normal random effect in the first level to contemplate a possible extra-binomial variability due to the dependence among the Bernoulli trials in the same individual. We obtain the maximum likelihood estimation process for this hierarchical model starting from the marginal likelihood of the data, after a double application of the adaptive Gauss-Hermite quadrature as an approximation of the integrals of the random effects. We conduct a simulation study to compare the inferential properties of the advocated model with the generalized linear (binomial) model, a quasi-likelihood model and the usual two-level hierarchical generalized linear model.

Cette thèse présente une nouvelle approche pour la modélisation des systèmes de sécurité fonctionnelle qui prend en compte plusieurs modes de défaillance pour les composants et le système global. Les diagrammes de flux d'information (IFDs) ont été initialement développé dans un thèse précédent. Dans ce travail, l'évaluation si l'approche flux d'information être rendue plus efficace par utiliser les diagrammes de décision binaires (BDD).Cette thèse sera d'expliquer pourquoi ce modèle est nécessaire et pratique, suivie d'une explication détaillée des IFDs. Cela inclut sa structure hiérarchique et comment ce modèle peut être appliqué.La prochaine étape est la formalisation du modèle IFD original pour permettre l'utilisation des techniques d'évaluation plus efficaces. Il sera expliqué pourquoi ces étapes de formalisation ont été prises et les avantages de leur utilisation.Ensuite une explication détaillée des algorithmes développés est présenté. Ces algorithmes sont basés sur une combinaison de différentes techniques de BDD. Zero Suppressed BDDs (ZBDDs) sont combinées avec des Boolean Expression Diagrams (BEDs). En outre, la structure des IFD est utilisé pour construire un BDD global sur plusieurs petits BDDs. Cela augmente l'efficacité du processus d'évaluation.Les techniques présentées sont évaluées par l'analyse de plusieurs cas d'utilisation qui sont expliqués dans ce travail / This thesis presents a novel approach for modelling safety critical systems which takes into account several failure modes both for components and the global system. The so called Information Flow Diagrams (IFDs) were originally developed in a previous PhD-thesis. In this work, the evaluation if the IFD-approach should be made more efficient by using Binary Decision Diagrams (BDDs).This thesis will explain why such a model is necessary and practical, followed by a detailed explanation of the IFD-model. This includes its hierarchical structure and how this model can be applied. The next step is to formalise the original IFD-model in order to enable more efficient evaluation techniques. It will be explained why these formalisation steps were taken and what was gained by using them. Afterwards a detailed explanation of the developed algorithms is presented. These algorithms are based on a combination of different BDD-techniques. Zero Suppressed BDDs (ZBDDs) are combined with Boolean Expression Diagrams (BEDs). Furthermore, the structure of the IFDs is used in order to construct a large BDD out of several smaller BDDs. This increases the efficiency of the evaluation process.The presented techniques are evaluated by analysing several use cases which are explained in this work

Na engenharia, existem diversas técnicas de análise estrutural que conduzem à obtenção de esforços e deslocamentos com considerável grau de eficácia e acurácia e, dentre estas, há a técnica de SUBESTRUTURAÇÃO. Esta técnica consiste na divisão e análise de um modelo estrutural completo, através da divisão de seu domínio em SUBESTRUTURAS, permitindo uma considerável eficiência nos cálculos e na avaliação de modelos estruturais combinados com a análise hierárquica de estruturas. Neste trabalho, seguindo-se a metodologia de pesquisa, que envolveu revisão bibliográfica e desenvolvimento de modelos computacionais, apresentaram-se as principais técnicas de subestruturas - seção 1, definições e formulação teórica dos principais métodos - desenvolvidos por Przemienieck (1963), Rosen e Rubinstein (1968), Rubinstein (1970) e El-Sayed e Hsiung (1990) - e a conceituação da análise hierárquica de estruturas com as respectivas aplicações combinadas com técnica de subestruturação para análise de fissuras em estruturas aeronáuticas, proposta de Starnes e Britt (1991) e aplicada por Potyondy (1993) - seção 2. Nesse contexto, na seção 3 se propôs a metodologia hierárquica para análise de estruturas típicas da construção civil, utilizando técnicas de subestruturação. Apresentaram-se instrumentos úteis à respectiva aplicação, dentre os quais se destaca a proposta de metodologia simplificada de análise hierárquica. Algumas precauções a serem adotadas na aplicação da metodologia também foram apresentadas. Na seção 4, desenvolveram-se cinco estudos de caso aplicando-se as metodologias, instrumentos e precauções desenvolvidos na seção 3, destacando-se a eficácia das metodologias. Conclui-se a pesquisa na seção 5 sendo que, na seção 6, indicam-se novas linhas de pesquisas a serem desenvolvidas sobre a metodologia proposta na pesquisa. / In engineering, there are several structural analysis techniques leading to obtain displacements and efforts with a considerable degree of efficacy and accuracy, and, among these, there is the SUBSTRUCTURING technique. This method consists in the division and analysis of a complete structural model, by subdividing his field in SUBSTRUCTURES, allowing a considerable efficiency in calculations and evaluation of structural models combined with hierarchical structures analysis. In this work, following the methodology research, which involved a literature review and computational models development, the key techniques of substructures were presented - section 1, as well as main methods definitions and theoretical formulation - developed by Przemienieck (1963), Rosen and Rubinstein (1968), Rubinstein (1970) and El-Sayed and Hsiung (1990) - and structural hierarchical analysis concept with their applications combined with aircraft structures cracks substructuring technical analysis, proposed by Starnes and Britt (1991), and implemented by Potyondy (1993) - Section 2. In this context, a civil construction typical structures analysis methodology was proposed in section 3. Besides, many useful tools for their implementation were presented, among which stands out the simplified hierarchy analysis methodology proposal. Some precautions in the methodology applying were also presented. In section 4, five case studies were developed, applying the methodology, tools and precautions explained in section 3, especially the methodologies effectiveness. The research is concluded in section 5, and new research lines, to be undertaken on the methodology proposed, were outpointed in section 6.

Para analisar dados binários oriundos de uma estrutura hierárquica com dois níveis (por exemplo, aluno e escola), uma alternativa bastante utilizada é a suposição da distribuição binomial para as unidades experimentais do primeiro nível (aluno) condicionalmente a um efeito aleatório proveniente de uma distribuição normal para as unidades do segundo nível (escola). Neste trabalho, propõe-se a adição de um efeito aleatório normal no primeiro nível de um modelo linear generalizado hierárquico binomial para contemplar uma possível variabilidade extra-binomial decorrente da dependência entre os ensaios de Bernoulli de um mesmo indivíduo. Obtém-se o processo de estimação por máxima verossimilhança para este modelo a partir da verossimilhança marginal dos dados, após uma dupla aplicação do método de quadratura de Gauss-Hermite adaptativa como aproximação para as integrais dos efeitos aleatórios. Realiza-se um estudo de simulação para contrastar propriedades inferenciais do modelo aspirante com o modelo linear generalizado binomial, um modelo de quase-verossimilhança e o tradicional modelo linear generalizado hierárquico em dois níveis. / A common alternative when analyzing binary data originated from a two-level hierarchical structure (for instance, student and school) is to assume a binomial distribution for the experimental units of the first level (student) conditionally to a normal random effect for the second level units (school). In this work, we propose the inclusion of a second normal random effect in the first level to contemplate a possible extra-binomial variability due to the dependence among the Bernoulli trials in the same individual. We obtain the maximum likelihood estimation process for this hierarchical model starting from the marginal likelihood of the data, after a double application of the adaptive Gauss-Hermite quadrature as an approximation of the integrals of the random effects. We conduct a simulation study to compare the inferential properties of the advocated model with the generalized linear (binomial) model, a quasi-likelihood model and the usual two-level hierarchical generalized linear model.

O design de sistemas automatizados inteligentes é fortemente dependente da etapa inicial de análise de requisitos, que além de suprimir possíveis incongruências - próprias desta fase inicial - provê um modelo inicial e funcional do sistema a ser implementado, capaz de orientar a definição dos parâmetros (design parameters) e em seguida a própria implementação. Um grande esforço tem sido empregado na área de Inteligência Artificial para definir planejadores automáticos confiáveis que possam ser usados na solução de problemas reais, que geralmente possuem um número elevado de parâmetros. Isto leva a uma situação onde métodos formais, geralmente aplicados em abordagens independentes de domínio, precisam ser aliados a métodos mais pragmáticos para produzir bons resultados. Seguindo esse princípio,o presente trabalho propõe um método de projeto no qual o usuário podem fazer a aquisição de conhecimento, modelar o domínio (tanto o domínio de aplicação quanto o domínio do problema de planejamento), fazer uma análise dinâmica do modelo e eventualmente verificá-lo usando linguagens conhecidas como UML, as Redes de Petri, e HTN, mantendo as características hierárquicas do problema. Esta abordagem demanda novos planejadores automáticos que consideram a abstração do sistema hierárquico, que é derivado de um modelo hierárquico de requisitos e de uma análise unificada feita também em redes de Petri hierárquicas. / The design of intelligent systems is strongly dependent of the requirements analysis initial stage, wich can remove possible inconsistencies - own this early stage - providing a primary functional model of the system being implemented. Besides that, it can be able to guide the definition of the parameters (design parameters) and then the implementation itself. A lot of effort has been employed in Artificial Intelligence field to define reliable automated planning systems that can be used to solve real problems, which generally have a large number of parameters. This leads to a situation where formal methods, generally applied to solve domain-independent problems, need to be combined with more pragmatic methods to produce good results. Following this principle, this work proposes a design method in which the user can make the acquisition of knowledge, model the domain (both the work domain and the planning problem domain), make a dynamic analysis of the model and eventually simulate it using well-kown language as UML, Petri Nets, and HTN, maintaining the hierarchical characteristics of the problem. This approach demands new automated planners who consider the abstraction of hierarchical system, which is derived from a hierarchical model requirements and an unified analysis made in hierarchical Petri nets.