Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This work proposes a methodology which is able to accomplish alarms processing and to estimate fault section in electrical power systems. The purpose is to filter alarms generated during a shutdown and indicate which equipment is at fault. To solve this problem, the methods employed are Constructive Heuristic (CH) and Integer Programming (IP) through their integration. Initially, CH method performs an analysis of fault direction in each power system equipment through alarms signaled by protective relays and circuit breakers status. Thus, by having as much information as possible, CH carries out an analysis on the level of equipment (busbars, power transformers and transmission lines) which can or cannot identify the direction in which disturbance occurred. The final processing is performed by IP, which analyzes the response of protection system as a whole (system-level analysis), using post-fault topology of power grid along with response of CH, indicating the fault section (s) and possible failures in the opening of circuit breakers. / Este trabalho propõe uma metodologia capaz de realizar o processamento de alarmes e estimar a seção em falta em sistemas elétricos de potência. A finalidade é filtrar os alarmes gerados durante um desligamento e indicar qual equipamento está sob falta. Para resolver o problema, são utilizados os métodos da Heurística Construtiva (HC) e da Programação Inteira (PI), através de sua integração. Inicialmente, o método da HC realiza, através dos alarmes sinalizados por relés de proteção e estado de disjuntores, uma análise quanto à direção da falta em cada equipamento do sistema de energia elétrica. Assim, a HC na posse de tantas informações quanto possível realiza uma análise em nível de equipamento (barramentos, transformadores de potência e linhas de transmissão), podendo ou não identificar a direção em que o distúrbio ocorreu. O processamento final é feito pela PI, que analisa a resposta do sistema de proteção como um todo (análise em nível de sistema), usando a topologia pós-falta da rede juntamente com a resposta da HC, indicando a(s) seção(ões) em falta(s) e as possíveis falhas de abertura em disjuntores.

La conception d'un système électrique est une tâche très complexe qui relève d’expertises dans différents domaines de compétence. Dans un contexte compétitif où l’avance technologique est un facteur déterminant, l’industrie cherche à réduire les temps d'étude et à fiabiliser les solutions trouvées par une approche méthodologique rigoureuse fournissant une solution optimale systémique.Il est alors nécessaire de construire des modèles et de mettre au point des méthodes d'optimisation compatibles avec ces préoccupations. En effet, l’optimisation unitaire de sous-systèmes sans prendre en compte les interactions ne permet pas d'obtenir un système optimal. Plus le système est complexe plus le travail est difficile et le temps de développement est important car il est difficile pour le concepteur d'appréhender le système dans toute sa globalité. Il est donc nécessaire d'intégrer la conception des composants dans une démarche systémique et globale qui prenne en compte à la fois les spécificités d’un composant et ses relations avec le système qui l’emploie.Analytical Target Cascading est une méthode d'optimisation multi niveaux de systèmes complexes. Cette approche hiérarchique consiste à décomposer un système complexe en sous-systèmes, jusqu’au niveau composant dont la conception relève d’algorithmes d'optimisation classiques. La solution optimale est alors trouvée par une technique de coordination qui assure la cohérence de tous les sous-systèmes. Une première partie est consacrée à l'optimisation de composants électriques. L'optimisation multi niveaux de systèmes complexes est étudiée dans la deuxième partie où une chaîne de traction électrique est choisie comme exemple / The design of an electrical system is a very complex task which needs experts from various fields of competence. In a competitive environment, where technological advance is a key factor, industry seeks to reduce study time and to make solutions reliable by way of a rigorous methodology providing a systemic solution.Then, it is necessary to build models and to develop optimization methods which are suitable with these concerns. Indeed, the optimization of sub-systems without taking into account the interaction does not allow to achieve an optimal system. More complex the system is more the work is difficult and the development time is important because it is difficult for the designer to understand and deal with the system in its complexity. Therefore, it is necessary to integrate the design components in a systemic and holistic approach to take into account, in the same time, the characteristics of a component and its relationship with the system it belongs to.Analytical Target Cascading is a multi-level optimization method for handling complex systems. This hierarchical approach consists on the breaking-down of a complex system into sub-systems, and component where their optimal design is ensured by way of classical optimization algorithms. The optimal solution of the system must be composed of the component's solutions. Then a coordination strategy is needed to ensure consistency of all sub-systems. First, the studied and proposed optimization algorithms are tested and compared on the optimization of electrical components. The second part focuses on the multi-level optimization of complex systems. The optimization of railway traction system is taken as a test case

Optimised allocation of system architectures is a well researched area as it can greatly reduce the developmental cost of systems and increase performance and reliability in their respective applications.In conjunction with the recent shift from federated to integrated architectures in automotive, and the increasing complexity of computer systems, both in terms of software and hardware, the applications of design space exploration and optimised allocation of system architectures are of great interest.This thesis proposes a method to derive architectures and their allocations for systems with real-time constraints.The method implements integer linear programming to solve for an optimised allocation of system architectures according to a set of linear constraints while taking resource requirements, communication dependencies, and manual design choices into account.Additionally, this thesis describes and evaluates an industrial use case using the method wherein the timing characteristics of a system were evaluated, and, the method applied to simultaneously derive a system architecture, and, an optimised allocation of the system architecture.This thesis presents evidence and validations that suggest the viability of the method and its use case in an industrial setting.The work in this thesis sets precedence for future research and development, as well as future applications of the method in both industry and academia.

No description available.

Le travail réalisé dans le cadre de cette thèse propose une démarche de sélection de partenaires (fournisseurs et prestataires) dans une chaîne logistique durable en boucle fermée. Il s’agit d’évaluer les partenaires en fonction de critères économiques, environnementaux, et sociétaux puis de sélectionner ceux qui interviennent dans la chaîne logistique en respectant un ensemble des contraintes. Nous développons une méthode d’évaluation et de classement des partenaires basée sur une approche hybride en utilisant les méthodes AHP et PROMETHEE, dans un environnement flou. Ensuite, nous proposons un modèle mathématique multi-objectif qui permet non seulement de minimiser le coût total de la chaîne logistique, mais également de maximiser la valeur totale de l’approvisionnement, minimiser les émissions de gaz à effet de serre et maximiser le bénéfice sociétal. Nous utilisons une approche max-min pondérée pour résoudre le modèle proposé à l’aide de l’outil de modélisation et d’optimisation GAMS. / Reverse logistics network design is a crucial issue in which it is important to take into account the selection of the most appropriate partner with sustainability concerns. This partner can be a supplier or a third-party reverse logistics provider (3PRLP). However, research works that consider reverse logistics (RL) network design, partner selection, and sustainability issues simultaneously are rather limited till now. This research work proposes an integrated sustainable approach for partner selection and closed-loop supply chain (CLSC) network configuration, particularly in the case of outsourcing reverse logistics process to third-party provider. We propose a trade-off between sustainability criteria for both supplier and 3PRL provider selection. A multi-objective mixed-integer programming (MILP) model is also proposed to configure CLSC network and to select the best partners. The model minimizes the total cost of sourcing, and the total greenhouse gas emissions, while it maximizes the total value of reverse logistics, and the number of new job opportunities. A numerical example is also presented to illustrate the proposed approach.

[pt] Esta tese de doutorado é composta de dois artigos científicos com contribuições na área de Smart Grid. Além disso, a tese também contribui para o desenvolvimento de soluções computacionais eficientes para problemas de programação linear mista e inteira. Outra importante contribuição é o desenvolvimento de método de decomposição benders com segundo estágio inteiro e não convexo aplicado ao problema de Transmission Switching. O primeiro artigo científico mostra os benefícios com o advento de uma rede inteligente e o aumento da capacidade do operador do sistema de energia elétrica em tomar ações corretivas em face de ocorrências de contingências. O artigo também analisa consequências práticas na capacidade de self-healing da rede pós-contingência. Em nosso contexto, uma rede self-healing é uma rede com total flexibilidade para ajustar a geração e as linhas de transmissão antes e depois da ocorrência de alguma contingência. Resultados numéricos mostram significantes reduções no corte de carga para cada contingência e no total. Foi considerado um único período que representa a demanda de pico do sistema, comparou-se o novo método com os utilizados em publicações anteriores. O segundo artigo contribui também para a aplicação da tecnologia de Smart Grid, em particular a teoria de Transmission Switching. De fato, desenvolvemos uma estratégia de solução para lidar com a complexibilidade NP-Hard criada pelas variáveis de transmission switching e unit commitment do problema de otimização. Foi desenvolvida uma solução algorítmica baseada na teoria dos grafos. Estudou-se a estrutura topológica desses problemas. Além disso, a maior contribuição foi o desenvolvimento de um novo método de decomposição de benders aplicado para o problema de transmission switching com o segundo estágio inteiro e não convexo. Para lidar com este problema de não convexidade, foi desenvolvido um método de convexificação sequencial, implícito a decomposição de benders. / [en] This PhD Thesis is composed by two papers with contributions on operations research applied to smart grid theory. The first paper highlights the economic and security benefits of an enhanced system operation with the advent of a smart grid technology by introducing a novel model, which is a joint energy and reserve scheduling that incorporates the network capability to switch transmission lines as a corrective action to enhance the system capability to circumvent contingency events. The main goal is to reduce operating costs and electric power outages, by adjusting the network connectivity when a contingency occurs. In such a framework, results show that, with a limited number of corrective switches, the system operator is able to circumvent a wider range of contingencies, while resulting in lower operational costs and reserve levels. In our context, a grid that is capable to adjust its generation and also its topology through post-contingency line switching is called a self-healing grid, and its importance in network security and operating costs is demonstrated in this work. The graph structure is explored in the algorithmic solution of the post-contingency transmission switching problem. Numerical results demonstrate a significant reduction in total load shedding and operating cost. It has been also illustrated an expressive improvement in terms of security and operating cost, in comparison to the transmission switching models previously published. The second paper is an application of a modified Benders decomposition to the post-contingency transmission switching problem. The decomposition is an attempt to deal with the NP-hard optimization problem created by the transmission switching and unit commitment variables. The major contribution is the application of a new benders decomposition approach to the problem of transmission switching, in which the first and second stages problems are a mixed-integer program. To deal with this issue, it is used a Branch and Bound (B&B) procedure for the first-stage problem and a sequential convexification procedure for the second-stage problem.

Dans cette thèse, nous considérons le problème du séquencement sur une ligne de montage multi-modèles de véhicules industriels. Pour équilibrer au mieux la charge dynamique des opérateurs, la minimisation de la somme des retards à l’issue de chaque véhicule est proposée.Deux approches peuvent être utilisées pour optimiser le lissage de charge dans un problème de séquencement : l’utilisation directe des temps opératoires ou le respect de règles. La plupart des travaux appliqués à l’industrie automobile utilisent l’approche de respect de règles. Une originalité de ce travail est d’utiliser l’approche de la prise en compte directe des temps opératoires.L’étude de la littérature de ce problème a dévoilé deux lacunes dans les travaux précédents : l’essentiel des travaux modélisent un seul type d’opérateurs d’une part, et proposent des heuristiques ou des métaheuristiques pour résoudre ces problèmes, d’autre part. L’originalité de ce travail est de tester des méthodes exactes pour des instances industrielles et de modéliser le fonctionnement de trois différents types d’opérateurs spécifiques au cas industriel.Deux méthodes exactes sont développées : la programmation linéaire mixte et la programmation dynamique. Une étude expérimentale des facteurs de complexité sur des instances académiques des deux modèles est développée. Les modèles sont aussi testés sur des instances du cas d’étude.Par ailleurs, le problème est traité par deux méthodes approchées : une heuristique basée sur la programmation dynamique d’une part, et des métaheuristiques (algorithme génétique, recuit simulé et un couplage des deux) d’autre part. Les deux approches sont testées sur des instances académiques et des instances du cas d’étude.Ce travail a permis d’apporter une solution intéressante d’un point de vue industriel puisqu’il prend en compte les caractéristiques de la ligne de montage (opérateurs spécifiques) et améliore significativement la qualité du séquencement en un temps de calcul raisonnable. / In this thesis, the problem of sequencing mixed model assembly lines (MMAL) is considered. Our goal is to determine the sequence of products to minimize the work overload. This problem is known as the mixed model assembly line sequencing problem with work overload minimization (MMSP-W). This work is based on an industrial case study of a truck assembly line.Two approaches can be used to minimize the work overload: the use of task operation times or the respect of sequencing rules. Most of the earlier works applied in car industry use the latter approach. The originality of this work is to employ the task operation times for the generation of the product sequence in a MMAL.The literature review has highlighted two main gaps in previous works: most of the papers consider a single type of operators, and propose heuristics or metaheuristics to solve the problem. The originality of this work is to test exact methods for industrial case instances and to model three different types of operators.Two exact methods are developed: the mixed integer linear programming and dynamic programming. The models are tested on industrial case study instances. An experimental study is developed for both approaches in order to understand the complexity factors.Moreover, the problem is treated by two approximate methods: a heuristic based on dynamic programming and metaheuristics (genetic algorithm, simulated annealing and a hybrid method based on both genetic algorithm and simulated annealing). All approaches are tested on academic instances and on real data from the industrial case study.

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No. of bitstreams: 1 souza_yp_me_guara.pdf: 1810118 bytes, checksum: 4638b9426aac62a064b565b38ffda481 (MD5) Previous issue date: 2018-08-27 / Neste trabalho propõe-se uma abordagem para o Problema de Balanceamento de Linhas de Montagem (do inglês, Assembly Line Balancing Problem - ALBP) para aumentar a eficiência de uma indústria montadora de veículos. O ALBP caracteriza-se como um problema de sequenciamento de tarefas em estações de trabalho classificado como um problema de Otimização Combinatória NP-difícil e, portanto, a solução exata do problema em ambientes reais geralmente implica em elevado custo computacional. Para resolver o ALBP, foram formulados um modelo matemático de otimização inteira mista para obtenção de soluções determinísticas e um modelo estocástico com recurso que considera a incerteza dos tempos de execução das tarefas pelos operadores. A motivação para o desenvolvimento do presente trabalho decorre da observação de interrupções constantes do fluxo de produção nesta indústria, atribuídas às mais diversas naturezas, e que causavam transtornos e elevados níveis de estresse aos trabalhadores. Ambos os modelos, determinístico e estocástico, aumentaram a capacidade de produção de 196 unidades/dia para 245 e 233 unidades/dia, respectivamente. O modelo estocástico aumentou o tempo de ciclo CT em 5,6% quando comparado ao modelo determinístico, embora diminua a capacidade efetiva em 4,8% Porém, não considerar a incerteza no tempo de execução das tarefas pode diminuir a quantidade produzida em até 10,6%. Contrariamente ao entendimento comum em linhas de montagem, este trabalho conclui que reduzir os tempos de ociosidade aos níveis mínimos é prejudicial à produtividade de linhas de montagem. Isto se deve ao fato de que uma parcela do tempo atribuído à ociosidade dos operadores, na verdade contêm um tempo adicional gerado pela incerteza do tempo de execução das tarefas. Os resultados sugerem que a abordagem do ALBP sob incerteza contribui para o aumento dos índices de capacidade operacional da empresa. Devido ao grande esforço computacional necessário para a solução dos modelos de otimização propostos (determinístico e estocástico), não se consegue resolver, em um tempo computacional razoável, exemplares de dimensões reais do problema. Em vista disto, o trabalho propõe também uma heurística para a solução do ALBP visando minimizar o tempo de ciclo. Experimentos computacionais sugerem que a heurística proposta obtém resultados razoáveis para grandes exemplares do problema em um tempo computacional pequeno / This work proposes solution approaches to the Assembly Line Balancing Problem (ALBP) to increase the efficiency of a vehicle assembler industry. The ALBP is characterized as a task sequencing in workstations which is classified as a NP-hard Combinatorial Optimization problem and, therefore, the exact solution of the problem in real environments usually implies a high computational cost. In order to solve the ALBP, a mathematical model of mixed integer optimization to obtain deterministic solutions and a stochastic model with resource that considers the uncertainty of the execution times of the tasks by the operators were formulated. The motivation for the development of this work stems from the constant interruptions of the production flow in this industry, attributed to the most diverse natures, which cause disorders and high levels of stress to the workers. The deterministic and stochastic models increased the production capacity from 196 units / day to 245 and 233 units / day, respectively. The stochastic model increased the cycle time by 5.6% when compared to the deterministic model, although it reduced the effective capacity by 4.8%, which is equivalent to 12 vehicles / day. However, not considering the uncertainty in task execution times can decrease the amount produced by up to 10.6% or 26 vehicles / day. Contrary to the most acceptable idea, this work concludes that reducing idle times to minimum levels is detrimental to assembly line productivity. This is due to the fact that a portion of the time attributed to the idleness of the operators actually contains an additional time generated by the uncertainty of the execution time of the tasks. The results suggest that the approach of the ALBP under uncertainty contributes to the increase of the indices of operational capacity of the company. Due to the great computational effort required to solve the proposed optimization models (deterministic and stochastic), it is not possible to solve real instances of the problem in a reasonable computational time. In view of this, this work also proposes a heuristic for the ALBP solution in order to minimize the cycle time. Computational experiments suggest that the proposed heuristic obtains reasonable results for large instances of the problem in a small computational time

Optical WDM network is the suitable transport mechanism for ever increasing bandwidth intensive internet applications. The WDM technique transmits the data over several different wavelengths simultaneously through an opticalfiber and the switching is done at wavelength level. The connection between the source and destination is called the light path. Since the WDM network carries huge amount of tra c, any failure can cause massive data loss. Therefore protecting the network against failure is an important issue. Maintaining high level of service availability is an important aspect of service provider. To provide cost effective service, all-optical network is the suitable choice for the service provider. But in all optical network, the signals are forced to remain in optical domain from source to destination. In the firrst part of the thesis, we deal the physical layer impairments (PLIs) aware shared-path provisioning on a wavelength routed all-optical networks. As the signal travels longer distances, the quality of the signal gets degraded and the receiver may not be able to detect the optical signal properly. Our objective is to establish a light path for both the working path and protection path with acceptable signal quality at the receiver. We propose an impairment aware integer linear programming (ILP) and impairment aware heuristic algorithm that takes into account the PLIs. The ILP provides the optimal solution. It is solved using IBM ILOG CPLEX solver. It is intractable for large size net-work. Therefore we propose the heuristic algorithm for large size network. It is evaluated through discrete-event simulation. But the algorithm provides only the suboptimal solution. To know the performance of this algorithm, the simulation result is compared with the optimal solution. We compute total blocking probability, restoration delay, computation time, and connection setup delay with respect to network load for the heuristic algorithm. We compare the performance of shared-path protection with dedicated-path protection and evaluate the percentage of resource saving of shared-path protection over the dedicated-path protection. In the second and third part of the thesis, we address the issues related to flexible-grid optical networks. In wavelength routed optical network, the bandwidth of each wavelength is fixed and rigid. It supports coarse grained tra c grooming and leads to ancient spectrum utilization. To overcome this, flexible-grid optical networks are proposed. It supports flexible bandwidth, and ne grained tra c groom In the second part of the thesis, we address the routing and spectrum allocation (RSA) algorithm for variable-bit-rate data tra c for flexible-grid optical networks. The RSA problem is NP-complete. Therefore a two-step heuristic approach (routing and spectrum allocation) is proposed to solve the RSA problem. The first step is solved by using a classical shortest path algorithm. For the second step we propose two heuristic schemes for frequency-slot allocation: (i) largest number of free frequency-slot allocation scheme and (ii) largest number of free frequency-slot maintaining scheme. As the network load increases, the spectrum is highly fragmented. To mitigate the fragmentation of the spectrum, we propose a xed-path least-fragmentation heuristic algorithm which fragments the spectrum minimally. It also supports varying-bit-rate tra c and also supports dynamic arrival connection requests. Through extensive simulations the proposed algorithms have been evaluated. Our simulation results show that the algorithms perform better in terms of spectrum utilization, blocking probability, and fraction of fragmentation of the spectrum. The spectrum utilization can reach up to a maximum of 92% and that only 71% of the spectrum is fragmented under maximum network load condition. Finally in the third part of the thesis, we discuss PLIs-aware RSA for the transparent exible-grid optical network. In this network, not only the optical signal expected to travel longer distance, but also to support higher line rates, i.e., data rate is increased up to 1 Tb/s. In such a high data rate, the optical signals are more prone to impairments and noises. As the transmission distance increases, optical signals are subject to tra-verse over many bandwidth-variable wavelength cross connects (BV-WXC) and multiple fibber spans due to which the PLIs get accumulated and are added to the optical signal. These accumulated impairments degrades the signal quality to an unacceptable level at the receiver, the quality of transmission falls below the acceptable threshold value, and the receiver may not be able to detect the signal properly. Therefore our objective is to develop an impairment aware RSA algorithm which establishes the QoT satisfied empathy based on the available resources and the quality of the signal available at the receiver. We formulate the PLIs-RSA problem as an ILP that provides an optimal solution. The optimal solution is obtained by solving the ILP using IBM ILOG CPLEX optimization solver. Since ILP is not efficient for large-size networks, we propose a heuristic algorithm for such a large-size networks. The signal power is measured at the receiver and the connection is established only when the signal power lies above the threshold value. The heuristic algorithm is evaluated through discrete-event simulation. It gives the sub-optimal solution. The simulation result is compared with optimal solution. The result shows that heuristic algorithm performs closer to the ILP. We compute the total blocking probability versus the network load for different spectrum allocation schemes. Total blocking probability is the sum of frequency-slot blocking probability and QoT blocking probability. We compute spectrum efficiency for the proposed algorithm. We also compare our algorithm with the existing routing and spectrum allocation algorithm, and the result shows that our algorithm outperforms the existing algorithms in terms of blocking probability and spectrum utilization.

No description available.