Procurement of sawlogs to purchasing sawmills represents a basic strategic business process. The properties of inbound sawlogs are decisive for the output of sawn products and the cost of raw material contributes substantially to the cost of the final product. Increasing customer orientation and new demands from powerful customers in the building and retail sectors entail new or accentuated demands on management of procurement. Managing raw material procurement and communicating needs to suppliers and logging machine operators are vital issues for sawmills in order to be competitive. The purpose of the thesis is to explore how purchasing sawmills manage procurement of sawlogs. The results are based on 46 in-depth interviews with people involved in the procurement process at seven softwood sawmills in Denmark, Finland and Sweden. The thesis identifies various types of supply uncertainties as well as process improvement and buffer activities that reduce uncertainties. However, the major obstacle in the procurement process is the power/dependence balance in the relationships with suppliers. Beyond doubt, it restricts the manageability of procurement and particularly bucking. The results suggest that there are a number of ways to improve management of procurement, which are currently not fully employed. The thesis provides four key strategic dimensions of the procurement process and suggests a general conceptual model of wood procurement to purchasing sawmills. Further research within the subject can usefully explore the link between procurement management and procurement strategy as well as the relation to other functions' strategies and the corporate strategy. The importance of the identified strategic dimensions of the procurement process needs to be quantified in order to provide normative suggestions.

Durant la dernière décennie, les développements technologiques en radiothérapie ont transformé considérablement les techniques de traitement. Les nouveaux faisceaux non standard améliorent la conformité de la dose aux volumes cibles, mais également complexifient les procédures dosimétriques. Puisque des études récentes ont démontré l’invalidité de ces protocoles actuels avec les faisceaux non standard, un nouveau protocole applicable à la dosimétrie de référence de ces faisceaux est en préparation par l’IAEA-AAPM. Le but premier de cette étude est de caractériser les facteurs responsables des corrections non unitaires en dosimétrie des faisceaux non standard, et ainsi fournir des solutions conceptuelles afin de minimiser l’ordre de grandeur des corrections proposées dans le nouveau formalisme de l’IAEA-AAPM. Le deuxième but de l’étude est de construire des méthodes servant à estimer les incertitudes d’une manière exacte en dosimétrie non standard, et d’évaluer les niveaux d’incertitudes réalistes pouvant être obtenus dans des situations cliniques. Les résultats de l’étude démontrent que de rapporter la dose au volume sensible de la chambre remplie d’eau réduit la correction d’environ la moitié sous de hauts gradients de dose. Une relation théorique entre le facteur de correction de champs non standard idéaux et le facteur de gradient du champ de référence est obtenue. En dosimétrie par film radiochromique, des niveaux d’incertitude de l’ordre de 0.3% sont obtenus par l’application d’une procédure stricte, ce qui démontre un intérêt potentiel pour les mesures de faisceaux non standard. Les résultats suggèrent également que les incertitudes expérimentales des faisceaux non standard doivent être considérées sérieusement, que ce soit durant les procédures quotidiennes de vérification ou durant les procédures de calibration. De plus, ces incertitudes pourraient être un facteur limitatif dans la nouvelle génération de protocoles. / During the past decade, technological developments in radiation therapy have considerably transformed treatment techniques. Novel nonstandard beams improve target dose conformity, but increase the complexity of dosimetry procedures. As recent studies demonstrated the invalidity of these protocols to nonstandard beams, a new protocol applicable to nonstandard beam reference dosimetry is in preparation by the IAEA-AAPM. The first goal of the study is to characterize the factors responsible for non-unity corrections in nonstandard beam dosimetry, and provide conceptual solutions to minimize the magnitude of the corrections. The second goal is to provide methods to estimate uncertainties accurately in nonstandard beam dosimetry, and estimate uncertainty levels achievable in typical clinical situations. Results of this study show that reporting dose to the sensitive volume of the chamber filled with water reduces the correction factor approximately by half under high gradients. A theoretical expression of correction factor is obtained for ideal nonstandard reference fields. In radiochromic film dosimetry, levels of uncertainty of the order of 0.3% are achieved with strict procedures and show great potential for nonstandard beam measurements. Results also suggest that experimental uncertainties in nonstandard beam are an important issue to consider both during daily QA routine and reference dosimetry, and could be a limiting factor in the new generation of protocols.

This thesis is a critical examination of phenomenological nuclear mean field theories, focusing on reliable description of levels of individual particles. The approach presented here is new in the sense that it not only allows to predict the numerical values obtained with this formalism, but also yields an estimate of the probability distributions corresponding to the experimental results. We introduce the concept of 'theoretical errors' to estimate uncertainties in theoreticalmodels. We also introduce a subjective notion of 'Predictive Power' of nuclear Hamiltonians, which is analyzed in the context of the energy spectra of individual particles. The mathematical concept of 'Inverse Problem' is applied to a realistic mean-field Hamiltonian. This technique allows to predict the properties of a system from a limited number of data. To deepen our understanding of Inverse Problems, we focus on a simple mathematical problem. A function dependent on four free parameters is introduced in order to reproduce 'experimental' data. We study the behavior of the 'fitted' parameters, their correlation and the associated errors. This study helps us understand the importance of the correct formulation of the problem. It also shows the importance of including theoretical and experimental errors in the solution.

Flexible structures are increasingly used in various applications such as aerospace, automotive and so on. Since they are lightly damped and susceptible to vibrations, active vibration control is desirable. In practice, in addition to achieving effective vibration reduction, we have also to consider the required control energy to avoid the energy insufficiency, the control input to avoid control saturation and reduce the effects of measurement noises. On the other hand, as flexible structures have infinite number of resonant modes and only the first few can be employed in the system modeling and the controller design, there always exist neglected high-frequency dynamics, which can induce the spillover instability. Furthermore, the parametric uncertainties on modal parameters can degrade the control performances and even destabilize the closed-loop system. In this context, a quantitative robust control methodology for active vibration control of flexible structure is proposed in this thesis. Phase and gain control polices are first proposed to enforce frequency-dependent phase and gain requirements on the controller, which can be realized by the output feedback H1 control design. The phase and gain control polices based H1 control can make a trade-off among the complete set of control objectives and offer a qualitative robust controller. Especially, the LPV H1 control is used to reduce the required control energy for LPV systems. The generalized polynomial chaos (gPC) framework with finite element analysis is employed for uncertainty quantification. It allows us to investigate the effects of structural property uncertainties on natural frequencies and achieve their probabilistic information. Then, in the presence of parametric and dynamic uncertainties, µ / v analysis and the random algorithm using Monte Carlo Method are used to quantitatively ensure the closed-loop stability and performance robustness properties both in deterministic and probabilistic senses. The proposed quantitative robust control methodology is thus developed by employing various techniques from automatic control and mechanical engineering, thus reducing the gap between them for robust vibration control of flexible structures. Its effectiveness are verified by numerical simulations and experimental validation on LTI and LPV non-collocated piezoelectric cantilever beams.

Submitted by JOHN WILLIAM NEGREIROS TERRONES null (johneter@hotmail.com) on 2018-01-19T17:02:53Z No. of bitstreams: 1 DissertaçãoJohn_JB (1).pdf: 14046795 bytes, checksum: deeec72b971c8015d40780ccc3ee8e37 (MD5) / Approved for entry into archive by Cristina Alexandra de Godoy null (cristina@adm.feis.unesp.br) on 2018-01-19T17:54:25Z (GMT) No. of bitstreams: 1 terrones_jwn_me_ilha.pdf: 14046795 bytes, checksum: deeec72b971c8015d40780ccc3ee8e37 (MD5) / Made available in DSpace on 2018-01-19T17:54:25Z (GMT). No. of bitstreams: 1 terrones_jwn_me_ilha.pdf: 14046795 bytes, checksum: deeec72b971c8015d40780ccc3ee8e37 (MD5) Previous issue date: 2017-09-06 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste trabalho, propõe-se uma metodologia baseada nas incertezas da radiação solar para prever o despacho de demanda e reativos nos sistemas de distribuição radial com geradores fotovoltaicos (GFs). O objetivo dessa metodologia é melhorar o perfil da magnitude de tensão para o dia seguinte, sujeito a certas restrições operativas do sistema elétrico de distribuição. No desenvolvimento dos algoritmos de solução são considerados geradores distribuídos que têm forte dependência das variações da fonte primária de energia (principalmente sistemas fotovoltaicos), ou seja, os limites de injeção de potência dos GFs dependem das incertezas da radiação solar. Este grupo de geradores precisa de considerações que incluam as incertezas na geração de energia. Para isso, elaboram-se cenários de radiação baseado na função de distribuição de probabilidade beta. Assim, são realizados fluxos de potência probabilísticos em múltiplos cenários. Leva-se em consideração, os objetivos a serem otimizados por meio de técnicas multiobjetivo, observando principalmente, os desvios da tensão nos nós e as perdas de potência nas linhas do sistema. A metodologia proposta foi implementada em linguagem de modelagem algébrica com o AMPL para descrever o problema de otimização e resolvido usando o solver comercial CPLEX. Os sistemas testes de 34 e 123 nós foram utilizados para avaliar os modelos matemáticos e a eficiência da técnica de solução proposta para o problema de controle dos sistemas de distribuição radiais com GFs. / This work presents a methodology based on uncertainties of solar radiation to predict demand and reactive dispatch in the radial distribution systems with photovoltaic generators (GFs). The objective is to improve the voltage magnitude profile for a day ahead, subjecting to operation constraints of distribution system. In order to evaluate the optimization criteria for distribution networks, active power balance equations have to be solved. It is considered that distributed generators have a high coherence to variations of the primary energy source (mainly photovoltaic systems), where, the power injection limits of the GFs depend on the uncertainties of the solar radiation. Uncertainties in generation are needed to be considered for this type of generator. Thus, the beta probability distribution function has been employed to include different radiation scenarios in the problem formulation. The aim of this research evolves the development of an optimization tool to predict the reactive power dispatch of GFs considering the uncertainties of solar radiation. For this purpose, the probabilistic power flow is performed under various scenarios. The Multiobjective optimization problem is formulated by including the buses (nodes) voltage deviations and the power losses of distribution lines in two different objective functions. The proposed methodology was implemented in AMPL mathematical model language and solved using the commercial CPLEX solver. The 34 and 123 nodes test systems are applied to show efficiency of presented mathematical models, i.e. control of radial distribution systems with GFs, and the proposed solution method.

Made available in DSpace on 2016-12-12T20:25:13Z (GMT). No. of bitstreams: 1 Gustavo Assis da Silva.pdf: 2694304 bytes, checksum: 361de063d220eeeebb77985807d4fc22 (MD5) Previous issue date: 2016-02-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This work addresses the use of the topology optimization of continuum structures under uncertainties in material properties associated to stiffness. The perturbation approach is used to perform the uncertainties quantification and the midpoint method is used for the random field discretization, where a decorrelation technique is used to reduce the computational effort. The finite element method is used for the domain discretization and the SIMP approach is used as material parameterization. Two problems are analyzed: the compliance minimization with volume constraint and the volume minimization with local stress constraints. The first problem is solved by using a optimality criteria method and the second problem by using the augmented Lagrangian method with a gradient based minimization method proposed in this work. The qp approach is used to avoid the singularity phenomenon in the problem with local stress constraints. Although this approach can be used considering uncertainty in any material property associated to stiffness ,the examples in this work show uncertainty only in Young s modulus. Different correlation lengths are considered to verify its influence in the optimum topologies. It is shown that the optimum topology, in both problems analyzed, becomes more distinct from the deterministic topology when the correlation length is reduced. / Este trabalho aborda o uso da otimização topológica de estruturas contínuas sob incertezas nas propriedades do material associadas à rigidez. O método de perturbação é utilizado para a quantificação de incertezas e o método do ponto médio é utilizado para a discretização do campo aleatório, onde uma abordagem de desacoplamento é utilizada para reduzir o custo computacional. O método dos elementos finitos é utilizado para a discretização do domínio e o modelo SIMP é utilizado na parametrização material. Dois problemas são analisados: o problema de minimização de flexibilidade com restrição de volume e o problema de minimização de volume com restrição local de tensão. O primeiro problema é solucionado utilizando-se um método de critério de ótimo e o segundo problema utilizando-se o método do Lagrangiano aumentado juntamente com um método de minimização baseado em gradiente proposto neste trabalho. Considerando-se o problema com restrição local de tensão, utilizou-se a relaxação qp para evitar o fenômeno de singularidade. Embora esta abordagem possa ser utilizada considerando-se incerteza em qualquer propriedade do material associada à rigidez, os exemplos ilustrados no trabalho apresentam incerteza apenas no módulo de elasticidade. Diferentes tamanhos de correlação são considerados de forma a verificar a sua influência na topologia ótima. Verifica-se que a topologia obtida, em ambos os problemas apresentados, torna-se mais distinta da topologia determinística com a redução do tamanho de correlação.

Orientador: Antonio Padilha Feltrin / Resumo: Neste trabalho, propõe-se uma metodologia baseada nas incertezas da radiação solar para prever o despacho de demanda e reativos nos sistemas de distribuição radial com geradores fotovoltaicos (GFs). O objetivo dessa metodologia é melhorar o perfil da magnitude de tensão para o dia seguinte, sujeito a certas restrições operativas do sistema elétrico de distribuição. No desenvolvimento dos algoritmos de solução são considerados geradores distribuídos que têm forte dependência das variações da fonte primária de energia (principalmente sistemas fotovoltaicos), ou seja, os limites de injeção de potência dos GFs dependem das incertezas da radiação solar. Este grupo de geradores precisa de considerações que incluam as incertezas na geração de energia. Para isso, elaboram-se cenários de radiação baseado na função de distribuição de probabilidade beta. Assim, são realizados fluxos de potência probabilísticos em múltiplos cenários. Leva-se em consideração, os objetivos a serem otimizados por meio de técnicas multiobjetivo, observando principalmente, os desvios da tensão nos nós e as perdas de potência nas linhas do sistema. A metodologia proposta foi implementada em linguagem de modelagem algébrica com o AMPL para descrever o problema de otimização e resolvido usando o solver comercial CPLEX. Os sistemas testes de 34 e 123 nós foram utilizados para avaliar os modelos matemáticos e a eficiência da técnica de solução proposta para o problema de controle dos sistemas de distribuição radia... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This work presents a methodology based on uncertainties of solar radiation to predict demand and reactive dispatch in the radial distribution systems with photovoltaic generators (GFs). The objective is to improve the voltage magnitude profile for a day ahead, subjecting to operation constraints of distribution system. In order to evaluate the optimization criteria for distribution networks, active power balance equations have to be solved. It is considered that distributed generators have a high coherence to variations of the primary energy source (mainly photovoltaic systems), where, the power injection limits of the GFs depend on the uncertainties of the solar radiation. Uncertainties in generation are needed to be considered for this type of generator. Thus, the beta probability distribution function has been employed to include different radiation scenarios in the problem formulation. The aim of this research evolves the development of an optimization tool to predict the reactive power dispatch of GFs considering the uncertainties of solar radiation. For this purpose, the probabilistic power flow is performed under various scenarios. The Multiobjective optimization problem is formulated by including the buses (nodes) voltage deviations and the power losses of distribution lines in two different objective functions. The proposed methodology was implemented in AMPL mathematical model language and solved using the commercial CPLEX solver. The 34 and 123 nodes test systems a... (Complete abstract click electronic access below) / Mestre

Il est connu qu’avoir un système d’observation de la pluie de haute résolution spatio – temporelle est crucial pour obtenir de bons résultats dans la modélisation pluie – écoulement. Le radar est un outil qui donne des estimations quantitatives de precipitation avec une très bonne résolution. Lorsqu’il est fusionné avec un réseau des pluviomètres les avantages des deux systèmes sont obtenus. Cependant, les estimations fournies par le radar ont des incertitudes différentes à celles qui sont obtenus avec les pluviomètres. Dans le processus de calcul pluie – écoulement l'incertitude des précipitations interagit avec l'incertitude du modèle hydrologique. L’objectif de ce travail est d’étudier les méthodes utilisées pour quantifier l'incertitude dans l'estimation des précipitations par fusion radar – pluviomètres et de l'incertitude dans la modélisation hydrologique, afin de développer une méthodologie d'analyse de leurs contributions individuelles au traitement pluie - écoulement.Le travail est divisé en deux parties, la première cherche à évaluer: Comment peut-on quantifier l'incertitude de l'estimation des précipitations par radar? Pour répondre à la question, l'approche géostatistique par Krigeage avec Dérive Externe (KED) et Génération Stochastique de la précipitation a été utilisée, qui permet de modéliser la structure spatio – temporaire de l’erreur. La méthode a été appliquée dans la région des Cévennes - Vivarais (France), où il y a un système très dense d'observation. La deuxième partie explique: Comment pourrais être quantifiée l'incertitude de la simulation hydrologique qui provient de l'estimation de précipitation par radar et du processus de modélisation hydrologique? Dans ce point, l'outil de calcul hydrologique à Mesoéchelle (HCHM) a été développé, c’est un logiciel hydrologique distribuée et temps continu, basé sur le Numéro de Courbe et l’Hydrographe Unitaire. Il a été appliqué dans 20 résolutions spatio - temporelles allant de 10 à 300 km2 et 1 à 6 heures dans les bassins de l’Ardèche (~ 1971 km2) et le Gardon (1810 km2). Apres une analyse de sensibilité, le modèle a été simplifié avec 4 paramètres et l’incertitude de la chaîne de processus a été analysée: 1) Estimation de precipitation; 2) Modélisation hydrologique; et 3) Traitement pluie - écoulement, par l’utilisation du coefficient de variation de l'écoulement simulé.Il a été montré que KED est une méthode qui fournit l’écart type de l’estimation des précipitations, lequel peut être transformé dans une estimation stochastique de l’erreur locale. Dans la chaîne des processus: 1) L'incertitude dans l'estimation de précipitation augmente avec la réduction de l’échelle spatio – temporelle, et son effet est atténué par la modélisation hydrologique, vraisemblablement par les propriétés de stockage et de transport du bassin ; 2) L'incertitude de la modélisation hydrologique dépend de la simplification des processus hydrologiques et pas de la surface du bassin ; 3) L'incertitude dans le traitement pluie - écoulement est le résultat de la combinaison amplifiée des incertitudes de la précipitation et la modélisation hydrologique. / It is known that having a precipitation observation system at high space - time resolution is crucial to obtain good results in rainfall - runoff modeling. Radar is a tool that offers quantitative precipitation estimates with very good resolution. When it is merged with a rain gauge network the advantages of both systems are achieved. However, radars estimates have different uncertainties than those obtained with the rain gauge. In the modeling process, uncertainty of precipitation interacts with uncertainty of the hydrological model. The objective of this work is: To study methods used to quantify the uncertainty in radar – raingauge merge precipitation estimation and uncertainty in hydrological modeling, in order to develop a methodology for the analysis of their individual contributions in the uncertainty of rainfall - runoff estimation.The work is divided in two parts, the first one evaluates: How the uncertainty of radar precipitation estimation can be quantified? To address the question, the geostatistical approach by Kriging with External Drift (KED) and Stochastic Generation of Precipitation was used, which allows to model the spatio - temporal structure of errors. The method was applied in the Cévennes - Vivarais region (France), where there is a very rich observation system. The second part explains: How can it be quantified the uncertainty of the hydrological simulation coming from the radar precipitation estimates and hydrological modeling process? In this point, the hydrological mesoscale computation tool was developed; it is distributed hydrological software in time continuous, within the basis of the Curve Number and the Unit Hydrograph. It was applied in 20 spatio-temporal resolutions ranging from 10 to 300 km2 and 1 to 6 hours in the Ardèche (~ 1971 km2) and the Gardon (1810 km2) basins. After a sensitivity analysis, the model was simplified with 4 parameters and the uncertainty of the chain of process was analyzed: 1) Precipitation estimation; 2) Hydrological modeling; and 3) Rainfall - runoff estimation, by using the coefficient of variation of the simulated flow.It has been shown that KED is a method that provides the standard deviation of the precipitation estimation, which can be transformed into a stochastic estimation of the local error. In the chain of processes: 1) Uncertainty in precipitation estimation increases with decreasing spatio-temporal scale, and its effect is attenuated by hydrological modeling, probably due by storage and transport properties of the basin; 2) The uncertainty of hydrological modeling depends on the simplification of hydrological processes and not on the surface of the basin; 3) Uncertainty in rainfall - runoff treatment is the result of the amplified combination of precipitation and hydrologic modeling uncertainties.

Submitted by Rodrigo Bernardes Ribeiro (rodrigo.bernardes@live.com) on 2017-01-12T02:12:02Z No. of bitstreams: 1 TCC_Completo_VF_Com_Ficha.pdf: 1319843 bytes, checksum: 1173593a6924491cb8937cbbba591670 (MD5) / Rejected by Renata de Souza Nascimento (renata.souza@fgv.br), reason: Rodrigo, boa tarde Por gentileza, retirar a acentuação do nome Getúlio para que possamos aceitar seu trabalho junto à biblioteca. Em seguida submeter o arquivo novamente. Grata. on 2017-01-12T15:21:27Z (GMT) / Submitted by Rodrigo Bernardes Ribeiro (rodrigo.bernardes@live.com) on 2017-01-12T16:46:08Z No. of bitstreams: 1 TCC_Completo_VF_Com_Ficha.pdf: 1317569 bytes, checksum: e3670ac2164fccd4740d66189fc68474 (MD5) / Approved for entry into archive by Renata de Souza Nascimento (renata.souza@fgv.br) on 2017-01-12T16:49:19Z (GMT) No. of bitstreams: 1 TCC_Completo_VF_Com_Ficha.pdf: 1317569 bytes, checksum: e3670ac2164fccd4740d66189fc68474 (MD5) / Made available in DSpace on 2017-01-12T17:10:47Z (GMT). No. of bitstreams: 1 TCC_Completo_VF_Com_Ficha.pdf: 1317569 bytes, checksum: e3670ac2164fccd4740d66189fc68474 (MD5) Previous issue date: 2016-12-14 / The present work aims to examine the risks and legal uncertainties and see how companies approach, treat and mitigate them, and how eventually this can be improved, especially in tax matters, considering the importance of its evaluation to record liabilities on financial reports, the practical effects of tax discussions and the impact of losing major litigation on taxpayers. It also seeks to elucidate the difficulties, mainly from the analysis of relevant tax discussions that are observed on the national scene and that occupy the most important courts in Brazil, and objectively point the accounting rules that must be observed by companies and the mechanisms which are usually used by them to ensure the quality of accounting judgments and consequently the information provided to external users. Given that accounting standards suggest that companies can rely on expert opinions and the perception that the opinions of lawyers have great relevance on legal risk evaluation, especially on tax matters, we analyze the way they are issued and what level of objectivity and accuracy can be expected from the loss or gain prognoses portrayed in them, to conclude that, although not as accurate, this tool is still the best mechanism available, given the peculiarities and uncertainties inherent in the law and the very indeterminacy of the future. Nevertheless, taking into account the basic characteristics of the risks, we beliebe that the knowledge of other areas on risk management, such as project management, can be adapted to law, in addition (and not replacement) to the legal opinions and the governance processes already implemented by the companies. Some tools that we consider capable of being applied to law are: (a) analysis of root causes and consequences; (B) numerical Linkert scale, combined with risks exposure in lists evaluated qualitatively; (C) Delphi technique. Finally, we present some practical effects of uncertainties and legal risks on tax matters and difficulties of its evaluation, to draw attention to the need of its management, as it is impossible to eliminate them. / O presente estudo tem como objetivo examinar os riscos e incertezas jurídicos e verificar como as empresas os abordam, tratam e mitigam e como, eventualmente, isso pode ser aprimorado, especialmente em matéria tributária, tendo em vista a importância da sua avaliação para registro das obrigações nas demonstrações financeiras, os efeitos práticos das discussões tributárias e os impactos das perdas dos grandes litígios para os contribuintes. Buscamos elucidar as dificuldades existentes, principalmente, a partir da análise de discussões tributárias relevantes que se observam no cenário nacional e que ocupam os mais importantes tribunais do País e apontar de forma objetiva as regras contábeis a serem observadas pelas empresas e os mecanismos usualmente utilizados por elas para assegurar a qualidade dos julgamentos contábeis e consequentemente das informações prestadas aos usuários externos. Diante da evidenciação de que a norma contábil sugere que as empresas se socorram das opiniões de especialistas e da percepção de que as opiniões dos advogados possuem grande relevância nas avaliações de riscos jurídico-tributários, buscamos analisar a forma como elas são emitidas e qual o nível de objetividade e precisão que se pode esperar dos prognósticos de perda ou ganho nelas retratados, para concluir que, embora não tão precisa, essa ferramenta ainda é o melhor mecanismo disponível, haja vista as peculiaridades e incertezas inerentes ao próprio Direito e a própria indeterminação do futuro. Não obstante, em atenção às características básicas dos riscos, verificamos que o conhecimento de outras áreas sobre o gerenciamento de riscos, como o gerenciamento de projetos, pode ser adaptado ao Direito, em adição (e não substituição) às opiniões jurídicas e aos processos de governança já implementados pelas empresas. Há algumas ferramentas que, para fins das conclusões a serem obtidas, são julgadas como aptas para serem aplicadas ao Direito, a saber: (a) análise de causa-raiz e de consequências; (b) escala Linkert numérica, com exposição dos riscos em listas avaliadas qualitativamente; (c) técnica Delphi. Por fim, apresentam-se alguns efeitos práticos das incertezas e riscos jurídico-tributários e das dificuldades de sua avaliação, para chamar a atenção para a necessidade de seu gerenciamento, em virtude da impossibilidade de sua efetiva eliminação.

Cette thèse porte sur le vieillissement des grands ouvrages en béton armé et précontraint dotés d’une fonction de confinement comme les bâtiments réacteurs des centrales nucléaires. Elle vise en particulier l'analyse probabiliste de l’évolution de leurs états de fissuration et de perméabilité dans le temps sous chargements Thermo-Hydro-Mécaniques (THM) simultanés et variables. L’étanchéité de telles structures est due à la faible perméabilité du béton mais reste conditionnée surtout par la maîtrise de la fissuration. Or, l'évolution de la perméabilité, l'apparition des fissures et leur propagation dépendent fortement de plusieurs aléas (les conditions de mise en œuvre, la variabilité spatio-temporelle des propriétés du béton et des chargements THM subis par la structure, etc.). Ainsi, la prise en compte de ces aléas dans les modèles numériques de vieillissement est une nécessité afin de permettre une meilleure évaluation de la performance de la structure dans son état présent et, surtout, permettre une prévision plus précise et plus fiable de son état futur. Pour y parvenir, cette thèse propose une stratégie globale de modélisation stochastique Thermo-Hydro-Mécanique avec post-traitement de la Fuite (THM-F), à l’échelle de Volumes Structurels Représentatifs, adaptée à la complexité du problème traité, au nombre important de paramètres THM-F intervenant dans les calculs et à son coût numérique. En particulier, les points suivants sont traités :(a) Modélisation du vieillissement tenant compte des effets de jeune âge : La modélisation des phénomènes de vieillissement est basée sur un modèle THM-F chaîné. En particulier, la modélisation proposée de la fissuration repose sur le couplage des lois d’échelle énergétique et des champs aléatoires autocorrélés selon une formulation locale, régularisée et vieillissante de l’endommagement. Cela permet une meilleure évaluation du risque de fissuration tant d’un point de vue qualitatif que quantitatif. Par conséquent, la prévision de l’étanchéité est aussi améliorée.(b) Identification des paramètres THM-F les plus influents : En appliquant une méthode d’analyse de sensibilité de type OFAT (One-Factor-At-a-Time) au modèle THM-F retenu, l’effet de la variabilité des différents paramètres en entrée sur la réponse numérique est quantifié. Cela permet de hiérarchiser les effets et de classifier les paramètres selon leur importance vis-à-vis du vieillissement (particulièrement en termes de fissuration et d’étanchéité).(c) Analyse de la propagation d’incertitudes THM-F : Des méthodes basées sur les surfaces de réponse (plans d’expérience adaptatifs, chaos polynomiaux) sont proposées pour construire des méta-modèles THM-F et analyser la propagation d’incertitudes moyennant un coût et une précision raisonnables. Étant donné la nature explicite des méta-modèles, la méthode de Monte Carlo est directement appliquée pour accéder à des fonctions de répartition, des indicateurs de sensibilité globaux et des analyses de fiabilité.L’applicabilité du modèle stochastique THM-F proposé aux grands ouvrages de confinement en béton armé et précontraint est évaluée en se basant sur la maquette VeRCoRs (enceinte de confinement à l’échelle 1 :3) selon des critères de représentativité physique du comportement et des mesures d’incertitudes simulés et de coût numérique. / Concrete is a heterogeneous, multiphasic and ageing material. Consequently, its properties show intrinsically spatiotemporal variations. For large reinforced and prestressed concrete structures such as Nuclear Containment Buildings (NCB), these variations directly affect the kinetic of their ageing process in terms of cracking, drying, creep and tightness. They also lead, within the structure's volume, to a non-negligible spatial heterogeneity of the concrete's behavior to the applied Thermo-Hydro-Mechanical (THM) loads during the operational lifespan. Consequently, the introduction of such variations in numerical models is a mandatory step to enhance the assessment of these structures’ present behavior and the accuracy of predictive analyses of their future one. With that aim in view, the thesis suggests a global coupling strategy of THM-L models (Thermo-Hydro-Mechanical with Leakage estimation) and non-intrusive stochastic approaches adapted for the strongly non-linear and time consuming simulations of ageing phenomena and the large number of inputs they require. Applied to the VeRCoRs mock-up (1:3 scaled containment building) at the scale of Representative Structural Volumes (RSV), this thesis addresses the following issues:(a) RSV-based modeling of concrete ageing from the early age phase: The modeling of concrete’s ageing is based on a staggered Thermo-Hydro-Mechanical with Leakage evaluation (THM-L) strategy. In particular, concrete cracking is modeled according to a Stochastic Size Effect Law (SSEL) and a regularized, local, ageing and damage-based constitutive model. The spatial heterogeneity of the concrete's properties (mainly the Young's modulus) is described using Random Fields (RF). This leads to a better description of concrete cracking both qualitatively and quantitatively. Accordingly, the modeling of the structural tightness is also improved.(b) Most influential THM-L parameters: Using a 1st order sensitivity analysis strategy (One-Factor-At-a-Time OFAT perturbation method), the relative effect of the THM-F parameters on the computed behavior is quantified. The obtained results show a hierarchized list of the most influential parameters and their associated physical phenomena. A selection is then achieved to keep relevant parameters only for uncertainty propagation step and higher-order sensitivity analyses throughout the THM-L coupling path.(c) Uncertainties propagation through THM-L calculation steps: Surface Response Methods (SRM) are used to define the associated RSV-based THM-L meta-models. For the stochastic modeling of concrete’s cracking an original Adaptive-SRM-based algorithm is suggested. Whereas for continuous THM-L quantities, a Polynomial Chaos based strategy is retained. Finally, as the meta-models are explicit within a defined and bounded domain, crude Monte Carlo Method is applied, at low cost, aiming at the CDFs and the reliability analysis of the considered variables of interest.Eventually, the suggested SFEM shall lead operators to a better quantification of uncertainties related to the behavior of their strategic civil engineering structures. This remains a crucial step towards the enhancement of durability assessment and repair/maintenance operations planning.