En los últimos años la Logística Inversa se ha hecho relevante no solo para el mundo académico sino también para el empresarial. Las empresas dan cada día más importancia a esta área, debido a los factores medioambientales y a los beneficios derivados del mejoramiento de su proceso de devoluciones. Así mismo, para tener unos procesos de Logística Inversa eficientes y exitosos, es necesaria la colaboración entre los miembros de la cadena de suministro. Esta tesis se concentra en ambos aspectos, Colaboración y Logística Inversa.El propósito de esta tesis es doble; primero, analizar los problemas que sufren hoy en día las empresas en esta área, partiendo de una perspectiva general, y posteriormente analizando la industria editorial española. En segundo lugar, nosotros proponemos cuatro modelos matemáticos concernientes a los problemas de planificación que presentan las empresas cuando incorporan las devoluciones, y finalmente proponemos unas metodologías para solucionarlos. / During last years Reverse Logistics has become a relevant topic not only for academics but also for the business world. Companies are giving each day more and more importance to this field, because the environmental issues and the benefits that the company can obtain by the improvement of their return's processes. To obtain a successful and efficient Reverse Logistics processes there exist the need to collaborate along the supply chain. This thesis focuses on both of these two topics, Collaboration and Reverse Logistics. The aim of this thesis is twofold; first, we try to understand the returns processes' problems that companies are facing today from the management point of view, from a general perspective and afterwards on the editorial industry. Secondly, we propose some mathematical models and solution methods related to real planning problems faced by the companies when the returns are incorporated.

Χωροθέτηση μονάδας επεξεργασίας ΑΣΑ σε συνδιασμό με τον απαραίτητο ΧΥΤΥ, με μικτό ακέραιο γραμμικό προγραμματισμό, για τη βελτιστοποίηση των ακολουθούμενων διαδρομών των απορριμματοφόρων προς την μονάδα επεξεργασίας και απο την μονάδα προς τον ΧΥΤΥ.Εγινε με εφαρμογή GIS στη Μεσσηνία. / The current thesis is about optimum siting of a MSW treatment plant combined with a landfill for residues based on mixed integer linear programming (MILP) and GIS methodology.

The current scenario of the Brazilian electricity sector, through the constant and recent regulatory changes imposed by ANEEL in recent years, aims to ensure continuous improvement in quality standards in the provision of electricity, significantly increased surveillance on the power quality delivered to consumers. Following this guideline, ANEEL established X Factor, which set the minimum volume of investments required to electricity distribution companies. In 2010, through the PRORET ANEEL established a new methodology for the calculation of the X Factor, including the Q component, relating to quality of service, setting a milestone in the recent regulatory history of the Brazilian electricity sector, as it allows for the first time gains the annual tariff adjustment or loss according to the performance measured in the year. In this context of regulatory innovations and increasing demands with performance standards and levels of investment made on the electrical system, the correct and efficient use of increasingly scarce resources to improve and expand the electrical system are presented as a vital challenge to financial health of companies. This paper presents a methodology for prioritizing investments in primary networks of electricity distribution, involving two consolidated methodologies aid to decision-making high complexity (AHP and PROMETHEE) and operations research methods to optimize the planning of improvement works to be held in short-term horizon, with direct reflection on regulatory issues, seeking still accommodate regional characteristics of the company and the ability to execute works of each region. / O atual cenário do setor elétrico brasileiro, através das constantes e recentes alterações regulatórias impostas pela ANEEL nos últimos anos, tem como objetivo garantir a melhoria contínua nos padrões de qualidade no fornecimento de energia elétrica, aumentado significativamente a fiscalização sobre a qualidade da energia entregue aos consumidores. Seguindo esta diretriz, a ANEEL instituiu o Fator X, que define o volume de investimentos mínimos exigidos às empresas de distribuição de energia elétrica. Em 2010, através do PRORET a ANEEL estabeleceu uma nova metodologia para o cálculo do Fator X, incluindo o componente Q, referente à qualidade do serviço prestado, configurando como um marco no recente histórico regulatório do setor elétrico brasileiro, pois permite pela primeira vez ganhos no reajuste tarifário anual ou perdas de acordo com o desempenho medido no ano. Neste contexto de inovações regulatórias e exigências cada vez maiores com os padrões de desempenho e níveis de investimentos realizados no sistema elétrico, a aplicação correta e eficiente dos cada vez mais escassos recursos disponíveis para melhoria e ampliação do sistema elétrico se apresentam como um desafio vital à saúde financeira das empresas do setor elétrico. Este trabalho apresenta uma metodologia para priorização de investimentos em redes primárias de distribuição de energia elétrica, associando duas consolidadas metodologias de auxílio à tomada de decisões de elevada complexidade (AHP e PROMETHEE) e métodos de pesquisa operacional para otimização no planejamento de obras de melhoria a serem realizadas no horizonte de curto prazo, com reflexo direto nas questões regulatórias, buscando ainda contemplar características regionais da empresa e a capacidade de execução de obras de cada região.

Le développement de structures de réseau efficaces pour le transport de marchandises est fondamental sur le marché mondial actuel. Les demandes doivent être traitées rapidement, répondre aux besoins des clients dans les meilleurs délais, les congestions et les retards doivent être minimisés, les émissions de CO2 doivent être contrôlés et des coûts de transport moins élevés doivent être proposés aux clients. La structure hub-and-spoke est un modèle de réseau courant utilisé à la fois dans le transport régional comme dans le transport intercontinental, permettant une économie d'échelle grâce aux consolidations opérées au niveau des noeuds hub. Mais, les retards, les congestions et les longs délais de livraison sont des inconvénients de ce type de réseau. Dans cette thèse, un nouveau concept, "sub-hub", est ajouté à la structure du réseau classique hub-and-spoke. Dans les modèles de réseau proposés, une économie d'échelle et des chemins alternatifs plus courts sont mis en oeuvre, en minimisant ainsi le coût de transport et le délai de livraison. Le sub-hub est vu comme un point de connexion entre deux routes distinctes de régions voisines. Des transbordements sans passer par les noeuds hub sont possibles au niveau des sub-hubs. Des congestions peuvent ainsi être évitées et, par conséquent, les retards associés sont ainsi minimisés. Quatre modèles de programmation linéaire en nombres entiers binaires du problème de la localisation de hubs et de routage sont développés dans cette thèse. Des réseaux avec sub-hub et des réseaux sans sub-hub prenant en compte des routes circulaires entre hubs ou des connexions directes entre hubs sont ainsi comparées. Ces modèles sont composés de quatre sous-problèmes (localisation, allocation, conception de service et routage) qui rendent complexe la recherche de solutions. Une approche cutting plane est testée pour résoudre de petites instances de problème tandis qu'une recherche à voisinage variable avec décomposition (VNDS) composée de méthodes exactes (matheuristic) a été développée pour résoudre de grandes instances. Le VNDS mis en oeuvre, explore chaque sous-problème avec différents opérateurs. Des gains importants dans la fonction objective sont observés par les modèles avec sub-hub confirmant ainsi le développement de réseaux plus compétitifs. / The development of efficient network structures for freight transport is a major concern for the current global market. Demands need to be quickly transported and should also meet the customer needs in a short period of time. Traffic congestions and delays must be minimized, since CO2 emissions must be controlled and affordable transport costs have to be offered to customers. Hub-and-spoke structure is a current network model used by both regional and intercontinental transportation, which offers an economy of scale for aggregated demands inside hub nodes. However, delays, traffic congestions and long delivery time are drawbacks from this kind of network. In this thesis, a new concept, which is called "sub-hub", is proposed to the classic hub-and-spoke network structure. In the proposed network models, economy of scale and shorter alternative paths are implemented, thus minimizing the transport cost and delivery time. The sub-hub proposal can be viewed as a connection point between two routes from distinct and close regions. Transshipments without the need to pass through hub nodes are possible inside sub-hubs. This way, congestions can be avoided and, consequently, delays are minimized. Four binary integer linear programming models for hub location and routing problem were developed in this thesis. Networks with sub-hub and networks without sub-hub taking into account circular hub routes or direct connections between hubs are compared. These models are composed of four sub-problems (location, allocation, service design and routing), which hinders the solution. A cutting plane approach was used to solve small instances of problem, while a Variable Neighborhood Decomposition Search (VNDS) composed of exact methods (matheuristic) was developed to solve large instances. The VNDS was used to explore each sub-problem by different operators. Major benefits are provided by models with sub-hub, thus promoting the development of more competitive networks.

Afin d’accélérer les flux de produits, de réduire les niveaux de stocks et de faire des économies de transport, les entreprises de presque toutes les industries ont mis en place des centres de crossdock. Ces centres sont un point intermédiaire de consolidation dans une chaîne logistique. Les constructeurs automobiles Renault et Nissan s’appuient sur un réseau international de plateformes crossdock pour lier des fournisseurs de pièces de première monte avec des usines de production lointaines, généralement en outre-mer. Dans un cadre d’un partenariat académique-industriel entre le laboratoire LIMOS et Renault, cette thèse est focalisée sur la planification et l’ordonnancement des activités dans ces centres de crossdock. Des études de terrain menées chez Renault et Nissan nous ont permis d’identifier les caractéristiques, les contraintes et les inducteurs de coûts des plateformes de crossdock, ainsi que de cibler notre revue de la littérature. Sur ces bases, nous proposons une approche d’optimisation séquentielle, comprenant deux modèles en programmation linéaire en nombres entiers, implémentés dans CPLEX et testés sur des données industrielles de deux plateformes Renault. Les résultats des expérimentations obtenus sur le premier modèle (planification) ont montré une nette amélioration en termes de coûts, par rapport à la méthode Renault. Fort de ce constat, une implémentation industrielle a été faite, avec des résultats aussi probants. Le deuxième modèle (ordonnancement) s’avère pertinent pour des instances de moyenne taille. L’approche proposée permet de répondre à la configuration actuelle des AILN Renault et nous considérons qu’elle est adaptable à d’autres industries. / In order to accelerate product flow, reduce inventory levels and make economies in transportation, companies in almost all industries have set up cross-dock centres. These centres are an intermediate point of consolidation in a supply chain. Car manufacturers Renault and Nissan rely on an international network of crossdock platforms to link suppliers of OEM parts with overseas production plants. In a framework of an academic-industrial partnership between the LIMOS laboratory and Renault, this thesis focuses on the activity planning and scheduling at these crossdock centres.Field studies conducted at Renault and Nissan allowed us to identify the characteristics, constraints and cost drivers of crossdock platforms, as well as to target our review of the literature. Based on this, we propose a sequential optimization approach, comprising two integer linear programming models, implemented in CPLEX and tested on industrial data of two Renault platforms. Numerical experiments’ results obtained on the first model (planning) showed a significant improvement in cost, compared to the Renault method. In light of this results, an industrial implementation was made, with such convincing results. The second model (scheduling) proved to be relevant for medium-sized instances. The proposed approach fits to the current configuration of AILN Renault and we consider that it is adaptable to other industries.

Les Réseaux de Chaleur (RdC) connaissent un nouvel essor en France qui s’explique par leur capacité à valoriser, à un prix raisonnable, des énergies bas carbone dans les domaines du chauffage et de l’eau chaude sanitaire aujourd’hui fortement émetteurs de CO2. L’amélioration du contrôle de ces systèmes complexes est un enjeu clé pour accroître leur compétitivité et favoriser leur développement. Cette thèse s’intéresse à la gestion par commande optimale des RdC. Pour cette application, nous avons développé et évalué un algorithme qui, à partir d’une prévision de la demande, optimise l’utilisation des différents moyens de production ainsi que la température de départ et la pression différentielle. Par rapport aux systèmes existants, les originalités de notre solution sont de tirer pleinement partie des capacités de stockage thermique dans le réseau et de déterminer le meilleur compromis entre coûts liés au pompage et pertes thermiques. Cette thèse débute par un travail de modélisation dynamique réalisé à l’échelle composant. En nous appuyant sur une démarche de validation expérimentale, nous avons systématiquement recherché le meilleur compromis entre précision et efficacité numérique (Chapitre 1). Le cas d’étude, décrit dans le Chapitre 2, est un RdC virtuel à l’échelle d’un quartier, représentatif du cas Grenoble. Pour le développement du système de gestion avancée, nous présentons ensuite une version linéarisée du modèle de réseau de distribution que nous intégrons à un optimiseur en suivant le formalisme de la programmation linéaire mixte. L’algorithme de gestion proposé est ensuite décrit (Chapitre 3). Il associe un modèle dynamique non-linéaire et l’optimiseur précité. L’objet du quatrième chapitre est l’évaluation des performances de notre algorithme par la simulation et la comparaison à des méthodes de contrôle existantes. Enfin, un dernier chapitre étudie la robustesse de l’algorithme en condition de commande réelle, c’est-à-dire en tenant compte de différentes sources d’incertitude. / District Heating (DH) are currently fast-growing in France. This situation is explained by their ability to exploit and disseminate massively, at a reasonable price, energy sources with low CO2 contents in the sectors of space heating and domestic hot water production, nowadays strongly emitters of greenhouse gases. Improving the control of these complex energy systems is a key issue for increasing their competitiveness and promote their development.This thesis focuses on the optimal control of DH systems. For this application, we have developed and tested an algorithm that optimizes, given a load prediction, the use of the production means, the supply temperature and the differential pressure. Compared to existing methods, the original features of the developed solution are to fully exploit the thermal storage capacity of the network and to determine the best compromise between costs for pumping and heat losses.This thesis begins with a work on dynamic modeling carried out at the component scale. Based on an experimental validation approach, we systematically sought the best compromise between accuracy and computational efficiency (Chapter 1). The case study, described in Chapter 2, is a virtual DH at the district scale, representing the Grenoble case. For the development of the advanced control system, we then present a linearized version of the distribution network model that we integrate into an optimizer relying on Mixed Linear Programming. The proposed control algorithm is described in Chapter 3. It combines a nonlinear dynamic model and the aforementioned optimizer. The topic of the fourth chapter is the evaluation of the performance of our algorithm by simulation and comparison with existing methods of control. A final chapter examines the robustness of the algorithm in real control conditions considering various sources of uncertainty.

[pt] Problemas de geração de grades horárias visam agendar eventos a fim de satisfazer demandas, ao mesmo tempo que satisfazem restrições adicionais. Uma solução é boa se todas as grades horárias resultantes são aceitáveis para todas as pessoas e recursos envolvidos. Para a geração de grades horárias escolares, um número conhecido de aulas, envolvendo estudantes, professores e salas de aula, deve ser agendado ao longo da semana, enquanto limitações operacionais, institucionais, pedagógicas e pessoais devem ser satisfeitas. A alta dificuldade do problema tem levado muitos pesquisadores a trabalhar em abordagens de resolução para o mesmo desde o início dos anos 60. Encontrar uma solução aplicável em um cenário do mundo real implica em satisfazer vários requisitos de qualidade e em não ignorar questões políticas, o que torna o problema clássico muito mais intrincado. Este trabalho descreve uma abordagem baseada em programação inteira mista (MIP) desenvolvida para resolver um problema real de geração de grades horárias escolares e discute ideias e desafios encarados durante a fase de implantação da solução em algumas escolas brasileiras. Em contraste com outros trabalhos na área, o compartilhamento de professores entre diferentes unidades de uma escola é considerado. Experimentos computacionais foram realizados para cenários cujo número de unidades varia de 2 a 15, o número de professores de 35 a 471, e o número de turmas de 16 a 295. Diferentes estratégias foram combinadas, visando a convergência da procura por boas soluções. Por fim, os resultados são avaliados e as melhores abordagens são destacadas. / [en] Timetabling problems look to schedule meetings in order to satisfy a set of demands, while respecting additional constraints. In a good solution the resulting timetables are acceptable to all people and resources involved. In school timetabling, a given number of lectures, involving students, teachers and classrooms, need to be scheduled over the week, while having to satisfy operational, institutional, pedagogical and personal restrictions. The difficulty of the problem has driven many researchers to work on solving approaches for it since the early 1960 s. Finding an actual solution to a real world scenario implies satisfying many quality requirements and not ignoring the political issues, which turns the classical problem much more intricate. This work describes an approach based on mixed integer programming (MIP) developed for solving a real-world school timetabling problem and discusses ideas and issues faced during solution deployment phase for some Brazilian schools. In contrast to other works on school timetabling, teaching staff sharing between distinct school units are considered. Computational experiments were performed for scenarios whose number of school units varies from 2 to 15, number of teachers varies from 35 to 471 and number of classes varies from 16 to 295. Different strategies were combined aiming at converging to good solutions. Finally, results are evaluated and the best approaches are highlighted.

In industrial applications, the thermal energy is obtained in specific equipment, such as boilers or heaters, and distributed to local usage through some transport fluid, mostly water vapor. Most industries uses multiple boilers to supply its steam demand, having tied operational costs. In this dissertation, was developed a mathematical optimization model in a language of algebraic modeling using GAMS® software. The aim is develop a computational systemic tool to support operational decisions of the steam generation. Generally, manufacturers do not operate simultaneously all of its steam generators. The choice of equipment to be used is a function of industrial process demand of steam. Regarding the use of such equipment, is not considered structured aid tools. The decisions were embased in the experience of those who were involved in operational activities. The model allows to identify specific situations to startup and shutdown, as well as the load on each boiler. In addition, the model provides estimates of steam production costs. Adjustments and evaluation of the applicability of the model occurred through a study case in a factory of the polyvinyl chloride production company, called Braskem S/A. The actual data provided by the company were compared to the results generated by the model, being evaluated their effectiveness. The results proved the model successful applicability, providing a direction, considering the generation of steam in the one year horizon. The application efficiency of the tool as a basis for the operation of steam generation was proved for long planning horizons and can be applied to shorter periods, such as weeks or months. / Em aplicações industriais, a energia térmica é obtida em equipamentos específicos, tais como caldeiras ou aquecedores, e distribuída aos locais de utilização através de um fluido de transporte, em sua maioria o vapor de água. A maior parte das indústrias utiliza várias caldeiras para suprir a demanda de vapor, havendo custos operacionais atrelados. Neste trabalho foi desenvolvido um modelo matemático de otimização em uma linguagem de modelagem algébrica, utilizando o software GAMS®. O intuito foi desenvolver uma ferramenta computacional sistêmica para apoiar as decisões operacionais de geração de vapor. De um modo geral, as indústrias não operam todos os geradores de vapor simultaneamente. A escolha do equipamento a ser utilizado, dentre os existentes na planta, é função da demanda de vapor dos processos industriais. No que diz respeito à utilização desses equipamentos, não se considera ferramentas de auxílio estruturadas, ficando as decisões embasadas na experiência dos envolvidos nas atividades operacionais. O modelo permitirá identificar situações específicas para acionamento e desligamento, bem como a carga em cada uma das caldeiras. Além disso, o modelo fornece estimativas dos custos de produção de vapor. Os ajustes e a avaliação da aplicabilidade do modelo ocorreram por meio de um estudo de caso realizado na unidade de produção de Policloreto de Viníla da empresa BRASKEM S/A. Os dados reais fornecidos pela empresa foram comparados aos resultados gerados pelo modelo, sendo avaliada sua eficácia. Os resultados obtidos comprovaram o sucesso na aplicabilidade do modelo, sendo obtido um direcionamento, considerando a geração de vapor no horizonte de um ano. A eficiência de aplicação da ferramenta como embasamento para a operação de geração de vapor foi comprovada para horizontes de planejamento longos, podendo ser aplicado a períodos mais curtos, como meses ou semanas.

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.

Le travail de thèse présenté dans ce mémoire porte sur des méthodes d'optimisation pour la conception conjointe des nomenclatures d'une famille de produits et de sa chaîne logistique. Dans les milieux industriels comme dans les services, le contexte commercial très concurrentiel oblige les entreprises à diversifier leurs offres pour mieux répondre aux demandes de leurs clients. La gestion de cette diversité est alors une problématique centrale : comment proposer une large variété de produits pour satisfaire les besoins des clients tout en maîtrisant les coûts de production, d'inventaire et de logistique ? Les réponses à ce problème relèvent des disciplines habituellement séparées : la conception des produits, la production et la logistique. Si une majorité des approches existantes traitent ces problématiques de façon séquentielle, l'interdisciplinarité apparaît cependant comme un élément essentiel dans la gestion de la diversité. L'objectif de cette thèse est de chercher comment améliorer les interactions entre la conception de familles de produits et l'optimisation des réseaux logistiques en proposant une étape de conception intermédiaire et en développant des outils mathématiques, avec un intérêt particulier porté aux problématiques de développement durable. / This PhD thesis addresses the problem of joint bills-of-materials and supply chain design for a product family. In industry as well as in services, the highly competitive business environment obliges companies to diversify their offers to meet the demands of their customers. Then, managing diversity is a central issue: how to offer a wide variety of products to meet customer needs while controlling costs of production, inventory and logistics? Answers to theses problems are usually in separate disciplines: product design, production and logistics. If most of existing approaches tackle these problems sequentially, interdisciplinarity, however, appears as a key aspect of diversity management. The objective of this thesis is to investigate how to improve the interaction between product families design and supply chain optimization and to develop mathematical tools, with a focus on sustainable development.