Lors d'une crue, la défaillance d'une digue fluviale est susceptible d'avoir des conséquences en vies humaines et économiques lourdes. Dans ce contexte, la réglementation sur la sécurité des ouvrages hydrauliques a récemment été renforcée (décret du 11 décembre 2007). Elle impose dorénavant aux gestionnaires la réalisation de diagnostics périodiques et encourage l'évaluation probabiliste de la sécurité des digues. De part leur caractère à grand linéaire, la complexité de leurs mécanismes de rupture et la grande variété de données nécessaires à leur diagnostic, les digues induisent des problématiques de diagnostic particulières, nécessitant l'intervention d'un ingénieur expert. Celui-ci doit procéder à l'analyse spatiale de l'information, l'interprétation des données disponibles et la prise en compte de leurs incertitudes. Il procède ensuite, par expertise, à l'évaluation qualitative de la performance des ouvrages. L'objectif de la thèse est l'élaboration d'un modèle d'aide à la décision probabiliste pour l'évaluation de la performance des digues. Ce modèle a vocation à être utilisé par un ingénieur spécialisé, en situation de diagnostic rapide ou approfondi et en valorisant toutes les données disponibles. Le modèle apporte une aide à l'ingénieur pour : identifier les tronçons homogènes d'un linéaire de digue, évaluer la performance des ouvrages pour les différents mécanismes de ruptures et préciser les niveaux d'incertitudes des résultats produits en fonction de l'imperfection des données disponibles. Notre démarche de recherche comporte trois étapes :- le développement d'un modèle fonctionnel des mécanismes de rupture des digues, bâti à partir de méthodes issues de la Sûreté de Fonctionnement et du Raisonnement Qualitatif ;- le développement d'un modèle d'aide à la décision déterministe comprenant des indicateurs de performance pour chaque mécanisme de rupture des digues, suivant une méthode de construction de critères uniques de synthèse ;- le développement d'un modèle d'évaluation probabiliste de la performance incluant une méthode de prise en compte des incertitudes des informations d'entrée et des résultats du modèle dans le cadre des probabilités subjectives. Les résultats de nos recherches sont illustrés par des applications du modèle à des études de cas, sur des digues fluviales et torrentielles / Levee risk control is crucial, as flood defense failures may seriously affect human life or economics issues. The regulation in France relating to the safety of the hydraulic structures is recently evolved (decree of December 11, 2007) and henceforth envisages for levees the realization of regular diagnoses and studies of dangers and encourages a probabilistic evaluation of levees safety. A levee safety evaluation currently consists in appraising the work, including taking into account data stemming from various prior investigations: historical records, visual inspections, hydraulic modeling, geophysical explorations, geotechnical explorations, etc. Such investigations may be performed to a more or less comprehensive extent, according to the resources available. Levee diagnostic studies will first split the alignments into several homogenous construction and loading sections, then complete an expert quality assessment of their performance levels. The goal of our research is to develop a probabilistic model for performance assessment of river levees, for a quick or comprehensive diagnosis. The model give support for engineer and make possible to determine how much an evaluation may be trusted and will help decide which levee sections should be primarily subjected to action or investigations. This will also facilitate the decision making process regarding technical actions to be taken to improve a levee section performance. Our approach contains three main steps:- analyzing and modeling levees failure mechanisms with a functional model build up from risk analysis methods ;- construction of deterministic decision aid model including levees performance indicator, using unicriterion decision support methods ;- construction of a probabilistic-based model for evaluating levees performance. Such model taking into account the input data uncertainty by using subjective probabilities. Our research results are illustrated by model application on cases studies

A large body of literature studies the issues of the option price and other ex-ante welfare measures under the microeconomic theory to valuate reductions of risks inherent in environment and human health. However, it does not offer a careful discussion of how to estimate risk reduction values using data, especially the modeling and estimating individual perceptions of risks present in the econometric models. The central theme of my dissertation is the approaches taken for the empirical estimation of probabilistic risks under alternative assumptions about individual perceptions of risk involved: the objective probability, the Savage subjective probability, and the subjective distributions of probability. Each of these three types of risk specifications is covered in one of the three essays. The first essay addresses the problem of empirical estimation of individual willingness to pay for recreation access to public land under uncertainty. In this essay I developed an econometric model and applied it to the case of lottery-rationed hunting permits. The empirical result finds that the model correctly predicts the responses of 84% of the respondents in the Maine moose hunting survey. The second essay addresses the estimation of a logit model for individual binary choices that involve heterogeneity in subjective probabilities. For this problem, I introduce the use of the hierarchical Bayes to estimate, among others, the parameters of distribution of subjective probabilities. The Monte Carlo study finds the estimator asymptotically unbiased and efficient. The third essay addresses the problem of modeling perceived mortality risks from arsenic concentrations in drinking water. I estimated a formal model that allows for ambiguity about risk. The empirical findings revealed that perceived risk was positively associated with exposure levels and also related individuating factors, in particular smoking habits and one’s current health status. Further evidence was found that the variance of the perceived risk distribution is non-zero. In all, the three essays contribute methodological approaches and provide empirical examples for developing empirical models and estimating value of risk reductions in environment and human health, given the assumption about the individual’s perceptions of risk, and accordingly, the reasonable specifications of risks involved in the models.

[pt] A avaliação de recursos petrolíferos não descobertos, isto é feita a partir de informações obtidas de testes indiretos como a sismografia, é a base para as decisões sobre a perfuração de poços de exploração. As informações disponíveis nessa fase que antecede a perfuração de poços são vagas e plenas de incertezas. Por outro lado, a avaliação econômica cuidadosa dos prospectos nessa fase é fundamental para as decisões relativas às fases seguintes, principalmente, devido ao elevado custo da perfuração de poços que nelas ocorrem. Por isso, a aplicação de métodos estatísticos que reduzam as incertezas na avaliação de recursos não descobertos é de grande importância para a rentabilidade das empresas de petróleo. O cálculo do volume recuperável de hidrocarbonetos (base para a avaliação econômica) depende avaliações feitas por especialistas e para considerar as incertezas inerentes aos dados as avaliações devem ser representadas probabilisticamente. O objetivo desta dissertação é rever as metodologias e técnicas formais para avaliação probabilística de recursos não descobertos encontradas na literatura, tendo sempre em mente os aspectos práticos de implementação. A descrição destas metodologias inclui a estrutura e a organização necessárias para gerenciar o trabalho dos especialistas, a eliciação de distribuições de probabilidades subjetivas e a combinação destas distribuições, além de técnicas para verificação de consistência das avaliações e redução de vieses. São feitas considerações sobre as principais distribuições de probabilidade usadas para representar incertezas inerentes à avaliação de fatores geológicos. Cada uma das metodologias e técnicas é exemplificada e discutida. Uma planilha eletrônica foi constituída com objeto de ilustrar os métodos apresentados e servir como protótipo de instrumento de apoio a avaliação probabilística de fatores geológicos. / [en] The evaluation of not discovered oil and gas resources, that uses solely information obtained from indirect tests such as seismography, is the base for the decisions on the drilling exploration wells. The information available in this phase that precedes the drilling of wells is vague and very uncertain. On the other hand, the careful economic evaluation of the prospects in this phase is very important for the decisions concerning the following phases, mainly on because of the high cost of the drilling of wells that occur. Therefore, the application of statistical methods for reducing the uncertainties and biases in the evaluation of undiscovered resources is quite important for the oil companies. The calculation of the recoverable volume of hydro-carbons (the basis for economic evaluation) depends on assessments made by experts, and for representing the uncertainties; the data must be probabilistically distributed. The objective of this thesis is to review the formal methodologies and techniques for probabilistic evaluation of undiscovered resources founded in literature, having always in mind the practical aspects of implementation. The description of these methodologies range from the definition of the structure and organization necessary to manage the work of the experts, the elicitation of distributions of subjective probabilities and the combination of these distributions, until techniques for verification of evaluations consistency and reduction of biases. Some considerations are made about the main distributions of probability used for representing the uncertainties in evaluations of geologic factors. Each methodology and technique is illustrated and discussed. An electronic spread sheet was developed to illustrate the presented methods and as a prototype of computer aid for the probabilistic evaluation of geologic factors.

We present some initial results on ontology-based query answering with description logic ontologies that may employ temporal and probabilistic operators on concepts and axioms. Speci_cally, we consider description logics extended with operators from linear temporal logic (LTL), as well as subjective probability operators, and an extended query language in which conjunctive queries can be combined using these operators. We first show some complexity results for the setting in which either only temporal operators or only probabilistic operators may be used, both in the ontology and in the query, and then show a 2ExpSpace lower bound for the setting in which both types of operators can be used together. / This is an extended version of an article accepted at Description Logics 2019.

The purpose with this study is to show how the subjective uncertainty analysis can be applied to the cost estimates and examine how the attitudes towards risk budgeting of construction projects works. Biogas Mellannorrland is based on a case study and focuses on four location options for the biogas plant. For each option, a cost estimate in form of a fixed cost and variable cost elements, where the latter are uncertain. Pearson-Tukey method have been applied as a method to estimating subjective probabilities. An assumption is made so that the uncertain costs are normally distributed, where the parameters’ mean and standard deviation collected from respondents indicating percentiles at 5% and 95% for doubtful cost elements. In order to identify the project managers risk attitude, the risk premium method will be used to calculate where the expected value is produced by Pearson-Tukey method. The expected value is subtracted with certainty equivalent, which consist of the budgeted amount. The study was conducted through interviews in order to obtain the costs and the subjective probabilities. The study results show that it is difficult to determine which option is the best, or the worst, by just looking at the expected value. The risk premium shows that each option is a risk averse choice for the project managers, since the risk premium was greater than zero. / Denna studie syftar till att visa hur subjektiv osäkerhetsanalys kan tillämpas vid kostnadskalkyler samt undersöka riskattityder vid budgetering av byggprojekt. Undersökningen är en fallstudie vid Biogas Mellannorrland och fokuserar på fyra lokaliseringsalternativ för biogasanläggning. För varje alternativ görs en kostnadskalkyl i form av ett antal fasta och rörliga delkostnader, där de senare är osäkra. Som metod för att skatta subjektiva sannolikheter har Pearson-Tukey-metoden tillämpats. Ett antagande görs att osäkra kostnader är normalfördelade, där parametrarna väntevärde och standardavvikelse hämtas från respondenter som anger percentilerna vid 5 % och 95 % för osäkra delkostnader. För att identifiera projektledarnas riskattityd, kommer riskpremium att beräknas, där det förväntade värdet tas fram med Pearson-Tukey- metoden. Det förväntade värdet subtraheras med säkerhetsekvivalensen, vilket utgörs av det budgeterade beloppet. Studien har genomförts med hjälp av intervjuer för att få fram kostnader och subjektiva sannolikheter. Studiens resultat visar att det är svårt att avgöra vilka alternativ som är bäst eller sämst genom att bara titta på väntevärdet. Med riskpremium visar alla alternativ att projektledarna gör ett riskaversivt val, eftersom riskpremium blev större än noll.

Une part importante de l’activité de communication humaine est dédiée au récit d’événements (fictifs ou non). Ces récits doivent être cohérents et intéressants pour être pertinents. Dans le domaine de la génération automatique de récits, la question de l’intérêt a souvent été négligée, ou traitée via l’utilisation de méthodes ad hoc, au profit de la cohérence des structures narratives produites. Nous proposons d’aborder le processus de création des récits sous l’angle de la modélisation quantitative de critères de pertinence narrative via l’application d’un modèle cognitif de l’intérêt événementiel. Nous montrerons que cet effort de modélisation peut servir de guide pour concevoir un modèle cognitivement plausible de génération de narrations. / Humans devote a considerable amount of time to producing narratives. Whatever a story is used for (whether to entertain or to teach), it must be relevant. Relevant stories must be believable and interesting. The field of computational generation of narratives has explored many ways of generating narratives, especially well-formed and understandable ones. The question of what makes a story interesting has however been largely ignored or barely addressed. Only some specific aspects of narrative interest have been considered. No general theoretical framework that would serve as guidance for the generation of interesting and believable narratives has been provided. The aim of this thesis is to introduce a cognitive model of situational interest and use it to offer formal criteria to decide to what extent a story is relevant. Such criteria could guide the development of a cognitively plausible model of story generation.