Este trabalho apresenta um modelo linearizado para ser utilizado em problemas de planejamento da expansão de sistemas de distribuição de energia elétrica (SDEE) com geração distribuída (GD), em um horizonte de curto prazo. O ponto de operação em regime permanente é calculado através de um modelo linearizado da rede, sendo as cargas e geradores representados por injeções constantes de corrente, o que torna possível calcular as correntes nos ramos e as tensões nas barras através de expressões lineares. As alternativas de expansão consideradas são: (i) alocação de bancos de capacitores; (ii) alocação de reguladores de tensão; e (iii) recondutoramento. Ainda, o modelo considera a possibilidade de seleção do tap dos transformadores de distribuição como alternativa para a redução das violações de tensão. A flexibilidade do modelo permite obter soluções considerando a contribuição das GDs no controle de tensão e potência reativa sem a necessidade de especificar uma tensão para a barra da subestação. O modelo de otimização proposto para a solução destes problemas utiliza uma função objetivo linear, além de restrições lineares e variáveis contínuas e binárias. Dessa forma, o modelo de otimização pode ser representado como um problema de programação linear inteira mista (PLIM) A função objetivo considera a minimização dos custos de investimento (aquisição, instalação e remoção de equipamentos e aquisição de condutores) e dos custos de operação, que correspondem aos custos anuais de manutenção somados aos custos das perdas de energia e das violações dos limites de tensão. A variação da carga é representada através de curvas de duração, sendo que os custos das perdas e das violações são ponderados pela duração de cada nível de carregamento. Utilizando uma abordagem de PLIM, sabe-se que existem condições suficientes que garantem a otimalidade de uma dada solução factível, além de permitir que a solução seja obtida através de métodos de otimização clássica. O modelo proposto foi implementado na linguagem de programação OPL e resolvido utilizando o solver comercial CPLEX. O modelo foi validado através da comparação dos resultados obtidos para cinco sistemas de distribuição com os resultados obtidos utilizando um fluxo de carga convencional. Os casos analisados e os resultados obtidos demonstram a precisão do modelo proposto e seu potencial de aplicação. / This work presents a linearized model to be used in short-term expansion planning problems of power distribution systems (PDS) with distributed generation (DG). The steady state operation point is calculated through a linearized model of the network, being the loads and generators modeled as constant current injections, which makes it possible to calculate the branch currents and bus voltages through linear expressions. The alternatives considered for expansion are: (i) capacitor banks placement; (ii) voltage regulators placement; and (iii) reconductoring. Furthermore, the model considers the possibility of adjusting the taps of the distribution transformers as an alternative to reduce voltage violations. The flexibility of the model enables solutions that includes the contribution of DGs in the control of voltage and reactive power without the need to specify the substation voltage. The optimization model proposed to solve these problems uses a linear objective function, along with linear constraints, binary and continuous variables. Thus, the optimization model can be represented as a mixed integer linear programming problem (MILP) The objective function considers the minimization of the investment costs (acquisition, installation and removal of equipment and acquisition of conductors) and the operation costs, which corresponds to the annual maintenance cost plus the costs related to energy losses and violation of voltage limits. The load variation is represented by discrete load duration curves and the costs of losses and voltage violations are weighted by the duration of each load level. Using a MILP approach, it is known that there are sufficient conditions that guarantee the optimality of a given feasible solution, besides allowing the solution to be obtained by classical optimization methods. The proposed model was written in the programming language OPL and solved by the commercial solver CPLEX. The model was validated through the comparison of the results obtained for five distribution systems with the results obtained through conventional load flow. The analyzed cases and the obtained results show the accuracy of the proposed model and its potential for application.

A indústria da construção civil é considerada como uma das grandes causadoras de impactos negativos ao meio ambiente, desde a extração de matéria prima, até o fim de vida de seus empreendimentos. Dentre os principais impactos ambientais ocasionados pelo setor, destacase a geração de resíduos de construção civil (RCC), a qual é intensificada em função do desenvolvimento de grandes centros urbanos e a consequente necessidade de implantação de empreendimentos de infraestrutura. Nesse contexto, uma das estratégias mais eficientes para redução de RCC está associada à realização de escolhas adequadas na fase de projeto, com enfoque de prevenção na fonte geradora. No entanto, é complexa a inclusão de fatores de sustentabilidade, tais como os de minimização de RCC, em projetos da construção civil. Logo, torna-se relevante a adoção de métodos e ferramentas de suporte ao processo decisório. Contudo, os métodos existentes são direcionados, em sua maioria, a projetos de edificações, havendo uma importante lacuna associada a projetos de infraestrutura urbana. Assim sendo, esta pesquisa objetiva a proposição de mecanismos de apoio à tomada de decisão, para a minimização de RCC, em projetos de infraestrutura urbana, com dois diferentes enfoques: controle e avaliação; e estrutura de orientação. Para a composição dos mecanismos de controle e avaliação, foram identificadas boas práticas para redução da geração de RCC na fase de projeto, a partir de pesquisa bibliográfica, análise documental de projetos, e pesquisa quali-quantitativa junto a especialistas. Essas boas práticas deram origem a demandas ambientais a serem atendidas pelos projetos de infraestrutura urbana, motivando a elaboração de um método estruturado para gerenciamento de requisitos ambientais e de trade-offs, como apoio à tomada de decisão projetual. O método teve como base a ferramenta Quality Function Deployment (QFD), no qual foi desdobrada a Matriz da Qualidade, a partir da opinião de especialistas atuantes em diferentes etapas do desenvolvimento de projetos de infraestrutura urbana. Como principais contribuições da pesquisa, focada na minimização de RCC, podem ser consideradas: (i) a obtenção de um checklist, como instrumento de controle e avaliação da qualidade dos projetos a serem desenvolvidos; (ii) a identificação de requisitos e de indicadores ambientais prioritários associados a esses projetos; e (iii) a elaboração de uma sistemática para gerenciamento de trade-offs existentes em projetos de infraestrutura urbana menos impactantes ambientalmente. / The construction industry is considered as one of the great causes of negative impacts to the environment, from the extraction of raw material, until the end-of-life of its projects. Among the main environmental impacts caused by the sector, can be highlighted the generation of construction waste (CW), which is intensified due to the development of large urban centers and the consequent need to implement infrastructure projects. In that context, one of the most efficient strategies to reduce CW is associated with making adequate choices in the design phase, with a focus on prevention at the source. However, it is complex to include sustainability factors, such as CW minimization, in construction designs. Therefore, it is relevant to adopt methods and tools to support the decision-making process. However, the existing methods are mostly directed to building designs, with an important gap associated with urban infrastructure designs. Thus, this research aims at proposing mechanisms to support decision making for the CW minimization in urban infrastructure projects, with two different approaches: control and evaluation; and guidance structure. For the composition of the control and the evaluation mechanisms, best practices were identified to reduce the CW generation in the design phase, based on literature review, documentary analysis of projects, and qualitative and quantitative surveys with specialists. Those best practices have given rise to environmental demands to be met by urban infrastructure projects, motivating the elaboration of a structured method for managing environmental requirements and trade-offs, as a support for the decision making design. The method was based on the Quality Function Deployment (QFD) tool, in which the quality matrix deployment, based on the opinion of specialists working in different stages of the development of urban designs. The main contributions of the research, focused on the CW minimization, can be considered: (i) obtaining a checklist, as an instrument to control and evaluate the quality of the designs to be developed; (ii) identification of requirements and of priority environmental indicators associated with those projects; and (iii) the development of a systematic for managing tradeoffs in urban infrastructure projects that are less environmentally impacting.

Problemas reais em áreas como aprendizado de máquina têm chamado atenção pela enorme quantidade de variáveis (> 10^6) e volume de dados. Em problemas dessa escala o custo para se obter e trabalhar com informações de segunda ordem são proibitivos. Tais problemas apresentam características que podem ser aproveitadas por métodos de busca em coordenada. Essa classe de métodos é caracterizada pela alteração de apenas uma ou poucas variáveis a cada iteração. A variante do método comumente descrita na literatura é a minimização cíclica de variáveis. Porém, resultados recentes sugerem que variantes aleatórias do método possuem melhores garantias de convergência. Nessa variante, a cada iteração, a variável a ser alterada é sorteada com uma probabilidade preestabelecida não necessariamente uniforme. Neste trabalho estudamos algumas variações do método de busca em coordenada. São apresentados aspectos teóricos desses métodos, porém focamos nos aspectos práticos de implementação e na comparação experimental entre variações do método de busca em coordenada aplicados a diferentes problemas com aplicações reais. / Real world problemas in areas such as machine learning are known for the huge number of decision variables (> 10^6) and data volume. For such problems working with second order derivatives is prohibitive. These problems have properties that benefits the application of coordinate descent/minimization methods. These kind of methods are defined by the change of a single, or small number of, decision variable at each iteration. In the literature, the commonly found description of this type of method is based on the cyclic change of variables. Recent papers have shown that randomized versions of this method have better convergence properties. This version is based on the change of a single variable chosen randomly at each iteration, based on a fixed, but not necessarily uniform, distribution. In this work we present some theoretical aspects of such methods, but we focus on practical aspects.

Nous présentons une nouvelle méthode pour la restauration d'images sismiques. Quand on l'observe, une image sismique est le résultat d'un système de dépôt initial qui a été transformé par un ensemble de déformations géologiques successives (flexions, glissement de la faille, etc) qui se sont produites sur une grande période de temps. L'objectif de la restauration sismique consiste à inverser les déformations pour fournir une image résultante qui représente le système de dépôt géologique tel qu'il était dans un état antérieur. Classiquement, ce procédé permet de tester la cohérence des hypothèses d'interprétations formulées par les géophysiciens sur les images initiales. Dans notre contribution, nous fournissons un outil qui permet de générer rapidement des images restaurées et qui aide donc les géophysiciens à reconnaître et identifier les caractéristiques géologiques qui peuvent être très fortement modifiées et donc difficilement identifiables dans l'image observée d'origine. Cette application permet alors d'assister ces géophysiciens pour la formulation d'hypothèses d'interprétation des images sismiques. L'approche que nous introduisons est basée sur un processus de minimisation qui exprime les déformations géologiques en termes de contraintes géométriques. Nous utilisons une approche itérative de Gauss-Newton qui converge rapidement pour résoudre le système. Dans une deuxième partie de notre travail nous montrons différents résultats obtenus dans des cas concrets afin d'illustrer le processus de restauration d'image sismique sur des données réelles et de montrer comment la version restaurée peut être utilisée dans un cadre d'interprétation géologique. / We present a new method for seismic image restoration. When observed, a seismic image is the result of an initial deposit system that has been transformed by a set of successive geological deformations (folding, fault slip, etc) that occurred over a large period of time. The goal of seismic restoration consists in inverting the deformations to provide a resulting image that depicts the geological deposit system as it was in a previous state. With our contribution, providing a tool that quickly generates restored images helps the geophysicists to recognize geological features that may be too strongly altered in the observed image. The proposed approach is based on a minimization process that expresses geological deformations in terms of geometrical constraints. We use a quickly-converging Gauss-Newton approach to solve the system. We provide results to illustrate the seismic image restoration process on real data and present how the restored version can be used in a geological interpretation framework.

A partir d’un ensemble de données interprétées et issues d’une analyse préalable par un opérateur expert (horizons, failles), l’objectif de la thèse est de proposer une segmentation d’une image sismique sous-jacente en parfaite cohérence avec les lois de la géologie. L’originalité de la démarche consistera à développer des techniques de segmentation d’images sismiques, entre autres basées sur des approches de type contours actifs, contraintes par des données interprétées en supplément de propriétés intrinsèques calculées par des procédés automatiques à partir de la donnée traitée sans nécessiter une quelconque supervision contrairement aux travaux existants. Un deuxième axe consistera à ordonnancer automatiquement les horizons (surfaces) interprétés et analyser finement chaque intervalle (le lieu existant entre deux horizons), en prenant en compte son contenu (amplitude, orientation, etc.). Tout cela aboutissant à la reconstruction du pseudo-temps géologique. / The objective of the thesis is to propose a segmentation of an underlying seismic image in perfect coherence with the results of a preliminary analysis by an expert (horizons, faults). laws of geology. The originality of the approach will be to develop techniques for segmenting seismic images, among others based on active contour type approaches, constrained by data interpreted in addition to intrinsic properties calculated by automatic processes from the data processed without requiring any supervision in contrast to existing work. A second axis will be to automatically schedule the horizons (surfaces) interpreted and to analyze each interval (the place between two horizons) finely, taking into account its content (amplitude, orientation, etc.). All this resulted in the reconstruction of the geological pseudo-time.

Distribution system plays a significant role in the overall electrical power system due to its impact on electricity costs, reliability as well as security of supplied energy. Optimal development planning of modern distribution system is mainly required to satisfy continuous change in customer demands and generations in a cost-effective manner, utilizing the available smart solutions. All these aspects need to be addressed in modern distribution planning methodology that can be applied today in real-life. Review has shown that there are no distributions planning models that adequately model security of supply of radially operated networks. Moreover, the optimal development planning models still do not consider multiple operating regimes, which has become a necessity due to connection of low carbon technologies. Numerous techniques published on this subject tend to ignore the regulations and planning standards that must be complied during system development, resulting in methodology that is not in-tuned with business practices. Furthermore, a comprehensive model that integrates all major components of today’s real-life distribution planning is still lacking, even though many of them have been addressed individually. In this thesis, integrated planning methodology for development of distribution system is proposed, incorporating utility practices in the UK. The overall methodology built on two independent stages, investment stage and operation stage. The operation stage is further cast into two sub-stages, quality of supply planning and minimization of operation costs planning. The overall planning methodology incorporates the novel probabilistic decision tree concept for distribution system planning to consider probable network uncertainties. The first model which is the investment stage determines the new construction and reinforcement of circuits and switchgear, along with circuit decommissioning. Multiple operating regimes due to fluctuation in generation and load profiles are considered, in addition to explicit modelling of N-1 security constraint according to P2/6 planning standards. The quality of supply planning determines the allocation of switchgear and its automation to maximise the reliability benefits from the regulatory incentive regime. Finally, the operation model determines the optimal network configuration that minimises the total operation costs of distribution system. The final outputs are list of cables and switchgear for construction, reinforcement, and decommission, benefits harvested due to quality of supply investments on switchgear, optimal network running arrangement, etc. These studies have proven to be important in formulating effective strategies for development of distribution system, in compliance to the planning standards and resulted in higher network operation capabilities.

O objetivo deste trabalho é apresentar uma nova abordagem para obtenção de configurações para sistemas de distribuição de energia elétrica com o intuito de minimizar o valor de perdas ativas sem violar as restrições operacionais. Para isso, considera-se que os sistemas de distribuição estão operando em regime permanente e que suas fases estão equilibradas e simétricas, podendo o sistema ser representado por um diagrama unifilar. A reconfiguração é feita de forma a redistribuir os fluxos de corrente nas linhas, transferindo cargas entre os alimentadores e melhorando o perfil de tensão ao longo do sistema. O problema de reconfiguração do sistema pode ser formulado como um problema de programação não-linear inteiro misto. Devido à explosão combinatorial inerente a este tipo de problema, a resolução do mesmo por técnicas de otimização clássicas torna-se pouco atraente, dando espaço para técnicas heurísticas e metaheurísticas. Essas outras, mesmo não garantindo o ótimo global, são capazes de encontrar boas soluções em um espaço de tempo relativamente curto. Para a resolução do problema de reconfiguração, utilizou-se uma nova metodologia baseada no comportamento de colônias de formigas em busca de alimento na natureza. Nesta, formigas artificiais (agentes) exploram o meio ambiente (sistema de distribuição) e trocam informações para tentar encontrar a topologia que apresente os menores valores de perdas ativas. Para o cálculo das perdas, este trabalho também apresenta uma nova abordagem para resolução do problema de fluxo de potência (FP) em sistemas de distribuição radial. O fluxo de potência é uma ferramenta básica utilizada pelos centros de controle para determinar os estados e condições operacionais desses sistemas de potência. Basicamente, as metodologias empregadas para o cálculo do fluxo de potência são baseadas nos métodos clássicos de Newton ou Gauss. Mas em sistemas de distribuição de energia, devido a particularidades inerentes a estes, como a alta relação entre resistência e reatância das linhas (r/x) e a operação radial, estes métodos apresentam problemas de convergência e se tornam ineficientes na maioria das vezes. A abordagem consiste na associação dos métodos da função penalidade e de Newton. O mal-condicionamento da matriz Jacobiana de Newton é resolvido pela associação com o método da função penalidade. São apresentados testes realizados em sistemas de 5 barras, 16 barras, 33 barras, 69 barras e 136 barras para avaliar a potencialidade das técnicas propostas. Os resultados são considerados bons ou muito bons quando comparado com as técnicas existentes atualmente. / The objective of this work is to present a novel methodology for obtaining new configurations of the distribution system in order to minimize the active power losses without violating operational constraints. For this, it is considered that any distribution system is operating in a steady state and that it is balanced, therefore it can be represented by a one-line diagram. The reconfiguration is done in order to redistribute de current flows on the distribution power lines, transferring loads among the feeders and improving the voltage profile along the system. Such problem can be formulated as a mixed integer nonlinear programming problem. Due to its inherent combinatorial characteristic and since its solution by classic optimization techniques is not appealing, heuristic and metaheuristic techniques are thus better suited for its solution. Although these latter do not guarantee a global optimum, they are able to find good solutions in a relatively short time. The solution of the reconfiguration problem in this approach makes use of a novel methodology based on ant colony behavior, when these search for victuals in nature. In this technique, the artificial ants (agents) explore the environment (distribution system) and exchange information among them in order to find the topology that provides the smallest active losses. For the active losses calculation, this work also presents a novel approach for the solution of the power flow problem for radial distribution systems. The solution of the power flow problem is used by system operators in order to determine the state and operational conditions of power systems. Basically, the most common techniques used in the power flow solution are based on either Newton\'s or Gauss\' approaches. However, due to particular characteristics of distribution systems such as the high ratio of r/x and the radial topology, these methods present convergence problems and are not efficient in most of the cases. Thus, this novel technique consists in associating Newton\'s and the penalty function approaches. The matter of the ill-conditioned Jacobian matrix in Newton\'s method is overcome with the penalty function method. Some tests performed in different systems are then presented in order to assess the effectiveness of both proposed techniques.

The urgent need for reform of USA and global food systems is evident in the pervasiveness of both food waste and food insecurity. Such an inefficient system strains the environmental, social, and economic systems on which it relies. Although policy and infrastructure changes are essential, consumers can play a significant role by decreasing their food waste, given that consumer waste represents 60% of the waste along the food cycle in developed countries. Incorporation of food literacy and food waste education in school curricula may provide a meaningful entry point for promoting food waste reduction skills. This dissertation presents context on the suitability of food systems for science and climate change education. Practical implementation of this concept is then explored through a survey of 495 students at Portland State University that presents the reported knowledge, attitudes, emotions, and beliefs related to food waste. The underlying factors that influence student food waste behavior and intent to change such behavior are likewise explored. I also provide a description and assessment of a food waste diversion program, No Scrap Left Behind, that was developed and piloted at PSU. I found that knowledge, attitudes, emotions, beliefs, and reported food-related behaviors were generally positive. Students were also interested in taking action and perceived that their food-related actions could make a difference. Intent to change food waste behaviors was influenced by: 1) sustainability actions, 2) food waste diversion actions, 3) attitudes about composting, 4) composting, 5) reported household food waste, 6) material reuse attitudes. Reported food waste diversion behaviors were related to: 1) intent to reduce food waste, 2) knowledge and attitudes towards composting, and 3) attitudes about reuse. The measures of reported knowledge, attitudes, emotions, beliefs, and behaviors were not significantly influenced by No Scrap Left Behind programming, but actual measured food waste was decreased by one-fourth both over an academic year and within an academic term of programming. This indicates that students are amenable to food waste behavior change when given the encouragement and infrastructure to make that change. Further research may consider opportunities for food waste education beyond the cafeteria setting, particularly as an entry into more complex discussions around environmental, social, and economic systems and concepts.

This thesis studies the generalization ability of machine learning algorithms in a statistical setting. It focuses on the data-dependent analysis of the generalization performance of learning algorithms in order to make full use of the potential of the actual training sample from which these algorithms learn.¶ First, we propose an extension of the standard framework for the derivation of generalization bounds for algorithms taking their hypotheses from random classes of functions. This approach is motivated by the fact that the function produced by a learning algorithm based on a random sample of data depends on this sample and is therefore a random function. Such an approach avoids the detour of the worst-case uniform bounds as done in the standard approach. We show that the mechanism which allows one to obtain generalization bounds for random classes in our framework is based on a “small complexity” of certain random coordinate projections. We demonstrate how this notion of complexity relates to learnability and how one can explore geometric properties of these projections in order to derive estimates of rates of convergence and good confidence interval estimates for the expected risk. We then demonstrate the generality of our new approach by presenting a range of examples, among them the algorithm-dependent compression schemes and the data-dependent luckiness frameworks, which fall into our random subclass framework.¶ Second, we study in more detail generalization bounds for a specific algorithm which is of central importance in learning theory, namely the Empirical Risk Minimization algorithm (ERM). Recent results show that one can significantly improve the high-probability estimates for the convergence rates for empirical minimizers by a direct analysis of the ERM algorithm. These results are based on a new localized notion of complexity of subsets of hypothesis functions with identical expected errors and are therefore dependent on the underlying unknown distribution. We investigate the extent to which one can estimate these high-probability convergence rates in a data-dependent manner. We provide an algorithm which computes a data-dependent upper bound for the expected error of empirical minimizers in terms of the “complexity” of data-dependent local subsets. These subsets are sets of functions of empirical errors of a given range and can be determined based solely on empirical data. We then show that recent direct estimates, which are essentially sharp estimates on the high-probability convergence rate for the ERM algorithm, can not be recovered universally from empirical data.

Cette thèse consiste en une série d'applications du calcul stochastique aux mathématiques financières. Elle est composée de quatre chapitres. Dans le premier on étudie le rapport entre la complétude du marché et l'extrémalité des mesures martingales equivalentes dans le cas d'une infinité d'actifs. Dans le deuxième on trouve des conditions équivalentes à l'existence et unicité d'une mesure martingale equivalente sous la quelle le processus des prix suit des lois n-dimensionnelles données à n fixe. Dans le troisième on étend à un marché admettant une infinité dénombrable d'actifs une charactérisation de la stratégie de couverture optimale (pour le critère moyenne-variance) basé sur une technique de changement de numéraire et extension artificielle. Enfin, dans le quatrième on s'occupe du problème de couverture d'un actif contingent dans un marché avec information asymetrique.