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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

A heuristic approach to supply chain network design in a multi-commodity four-echelon logistics system

Farias, Everton da Silveira January 2016 (has links)
Nesta tese propõe-se um método heurístico para o problema de Projeto de Rede da Cadeia de Suprimentos (Supply Chain Network Design) considerando vários aspectos de relevância prática, tais como: fornecedores e matérias-primas, localização e operação de instalações, atribuição de Centros de Distribuição (CD), e grande número de clientes e produtos. Uma eficiente abordagem heurística de duas fases é proposta para a obtenção de soluções viáveis para os problemas, que inicialmente é modelado como um Programa Linear Inteiro Misto (PLIM) de grande escala. Na fase de construção, uma estratégia de Linear Programming Rounding é aplicada para se obter os valores iniciais para as variáveis de localização inteira do modelo. Simultaneamente, um método Multi-start foi desenvolvido para gerar soluções iniciais diversificadas para cada nova iteração da heurística de Rounding. Na segunda fase, dois procedimentos de Busca Local foram desenvolvidos no sentido de melhorar a solução fornecida pelo método de Rounding. Implementamos duas diferentes abordagens de Busca Local: remoção-inserção e troca. Uma técnica de Busca Tabu para orientar o procedimento de Busca Local para explorar os diferentes espaços de soluções foi desenvolvida. As formulações e algoritmos foram implementados na linguagem C++ utilizando ferramentas de otimização da COIN-OR. O método de solução foi experimentado em instâncias geradas aleatoriamente, com tamanhos diferentes em termos do número de parâmetros, tais como o número de produtos, zonas de clientes, CDs e fábricas considerando um sistema logístico de quatro níveis. As implementações computacionais mostram que o método de solução proposto obteve resultados satisfatórios quando comparados com a literatura. Para validar este método heurístico também foi usado em um caso realista, com base em dados de uma empresa de borracha que está reestruturando sua cadeia de suprimentos devido ao projeto de uma nova uma nova fábrica e produção de novos produtos. A abordagem heurística proposta revelou-se adequada para aplicação prática em um caso real de uma indústria multicommodity em um contexto determinístico. / In this thesis we propose a heuristic method for the Supply Chain Network Design (SCND) problem considering several aspects of practical relevance: suppliers and raw materials, location and operation facilities, distribution center (DC) assignments, and large numbers of customers and products. An efficient two-phase heuristic approach is proposed for obtaining feasible solutions to the problems, which is initially modeled as a large-scale Mixed Integer Linear Program (MILP). In the construction phase, a linear programming rounding strategy is applied to obtain initial values for the integer location variables in the model. Simultaneously, a Multi-start method was developed to generate diversified initial solutions from each new iteration in the rounding heuristic. In the second phase, two Local Search procedures were developed towards to improve the solution provided by the rounding method. We implemented two different Local Search approaches: removal-insertion and exchange. A Tabu Search technique was developed to guide the Local Search procedure to explore the different spaces of solutions. The formulations and algorithms were implemented in C++ code language using the optimization engine COIN-OR. The solution method was experimented in randomly generated instances, with different sizes in terms of the number of parameters, such as number of products, customer zones, DCs, and factories considering a four-echelon logistic system. The computational implementations show that the solution method proposed obtained satisfactory results when compared to the literature review. To validate this heuristic method was also used in a realistic case, based on data from a rubber company that is restructuring its supply chain due to the overture of a new factory, producing new products. The proposed heuristic approach proved appropriate to practical application in a realistic case of a multi commodity industry in a deterministic context.
82

MOIRAE : a computational strategy to predict 3-D structures of polypeptides

Dorn, Márcio January 2012 (has links)
Currently, one of the main research problems in Structural Bioinformatics is associated to the study and prediction of the 3-D structure of proteins. The 1990’s GENOME projects resulted in a large increase in the number of protein sequences. However, the number of identified 3-D protein structures have not followed the same growth trend. The number of protein sequences is much higher than the number of known 3-D structures. Many computational methodologies, systems and algorithms have been proposed to address the protein structure prediction problem. However, the problem still remains challenging because of the complexity and high dimensionality of a protein conformational search space. This work presents a new computational strategy for the 3-D protein structure prediction problem. A first principle strategy which uses database information for the prediction of the 3-D structure of polypeptides was developed. The proposed technique manipulates structural information from the PDB in order to generate torsion angles intervals. Torsion angles intervals are used as input to a genetic algorithm with a local-search operator in order to search the protein conformational space and predict its 3-D structure. Results show that the 3-D structures obtained by the proposed method were topologically comparable to their correspondent experimental structure.
83

Efficient modularity density heuristics in graph clustering and their applications

Santiago, Rafael de January 2017 (has links)
Modularity Density Maximization is a graph clustering problem which avoids the resolution limit degeneracy of the Modularity Maximization problem. This thesis aims at solving larger instances than current Modularity Density heuristics do, and show how close the obtained solutions are to the expected clustering. Three main contributions arise from this objective. The first one is about the theoretical contributions about properties of Modularity Density based prioritizers. The second one is the development of eight Modularity Density Maximization heuristics. Our heuristics are compared with optimal results from the literature, and with GAOD, iMeme-Net, HAIN, BMD- heuristics. Our results are also compared with CNM and Louvain which are heuristics for Modularity Maximization that solve instances with thousands of nodes. The tests were carried out by using graphs from the “Stanford Large Network Dataset Collection”. The experiments have shown that our eight heuristics found solutions for graphs with hundreds of thousands of nodes. Our results have also shown that five of our heuristics surpassed the current state-of-the-art Modularity Density Maximization heuristic solvers for large graphs. A third contribution is the proposal of six column generation methods. These methods use exact and heuristic auxiliary solvers and an initial variable generator. Comparisons among our proposed column generations and state-of-the-art algorithms were also carried out. The results showed that: (i) two of our methods surpassed the state-of-the-art algorithms in terms of time, and (ii) our methods proved the optimal value for larger instances than current approaches can tackle. Our results suggest clear improvements to the state-of-the-art results for the Modularity Density Maximization problem.
84

Reconfiguração de sistemas de distribuição de energia elétrica utilizando uma metodologia multipartida / Distribution network reconfiguration problem using a multi-start methodology

Cardona, Natalia Patiño [UNESP] 16 February 2016 (has links)
Submitted by NATALIA PATINO CARDONA null (npatcar@gmail.com) on 2016-03-15T18:03:52Z No. of bitstreams: 1 Natalia_Patino_Cardona.pdf: 3586616 bytes, checksum: 280eb15150f150a3d1e6d5b25ffb2c20 (MD5) / Approved for entry into archive by Sandra Manzano de Almeida (smanzano@marilia.unesp.br) on 2016-03-15T18:17:50Z (GMT) No. of bitstreams: 1 cardona_np_me_ilha.pdf: 3586616 bytes, checksum: 280eb15150f150a3d1e6d5b25ffb2c20 (MD5) / Made available in DSpace on 2016-03-15T18:17:50Z (GMT). No. of bitstreams: 1 cardona_np_me_ilha.pdf: 3586616 bytes, checksum: 280eb15150f150a3d1e6d5b25ffb2c20 (MD5) Previous issue date: 2016-02-16 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este trabalho apresenta uma proposta baseada na metodologia multipartida para a resolução do Problema de Reconfiguração de Sistemas de Distribuição de Energia Elétrica, de natureza combinatória e modelado como um problema de Programação Não Linear Inteiro Misto. O objetivo principal deste trabalho é encontrar a topologia radial ótima para minimizar as perdas ativas dos sistemas de distribuição, e para isso é preciso, primeiramente, a resolução de um problema de fluxo de potência para sistemas fracamente malhados onde é calculada a potência aparente do sistema, a qual vai ser utilizada pelo algoritmo de Prim como o peso para a geração das soluções iniciais radiais de boa qualidade. Para implementar a metodologia proposta deve-se desenvolver também um algoritmo de fluxo de potência radial, utilizado para calcular tanto as perdas ativas do sistema (função objetivo do problema), como para verificar a factibilidade das propostas de solução. Nesta primeira etapa é feita uma variação aleatória dos pesos dos ramos, e são resolvidos tantos problemas de fluxo de potência radial quanto soluções aleatórias obtidas, para encontrar soluções de boa qualidade próximas ao ótimo. Finalmente, é feita uma busca local através da troca de ramos como tentativa para encontrar a solução ótima. As soluções obtidas pela metodologia proposta são obtidas através da programação de algoritmos implementados em linguagem C++. Os resultados obtidos mostram a eficiência da aplicação da metodologia, estes resultados foram comparados com os existentes na literatura e os obtidos pela resolução de um modelo de otimização resolvido com o solver comercial CPLEX. / This work presents a proposal based on multi-start methodology for the solution of the distribution network reconfiguration problem, of combinatorial nature and modeled as a mixed-integer nonlinear programming problem. The main objective of this work is to find the optimal radial topology to minimize active power losses in distribution systems. This requires, at first, the resolution of a power flow problem for weakly meshed systems where the apparent power of the system is calculated, which will be used by the Prim algorithm as the weight for generating the radial initial good quality solution. To implement the proposed methodology is also developed a radial power flow algorithm, used to calculate both the active system losses (objective function of the problem) and to verify the feasibility of the proposed solutions. In this first stage is made a random variation of the weights of branches, and there are solved as many radial power flows as random solutions obtained, to find good quality solutions close to optimal. Finally, a local search is made by doing an exchange of branches as an attempt to find the optimal solution. The solutions obtained by the proposed method are acquired by programming algorithms implemented in C ++ language. The results show the effectiveness of the application of the methodology. These results were compared with those in the literature and those obtained by solving an optimization model solved by the commercial solver CPLEX.
85

Modèles de résolution approchée et efficace pour les problèmes des réseaux de transport et de télécommunication / Approached and effective resolution models for vehicle routing and telecommunication networks problems

Bouchakhchoukha, Adel 27 November 2015 (has links)
La capacité à gagner du temps et à diminuer ses efforts est l'une des qualités de l'être humain, qui a conduit à exercer la pensée depuis l'Antiquité jusqu'à ces dernières décennies, caractérisées par l'émergence du mélange entre la rapidité des calculs et la précision des résultats, et ce dans plusieurs domaines. Le problème des tournées de véhicules et ses extensions sont, pour les théoriciens de ces utilités, d'une réelle importance quant aux applications du monde réel. Des recherches récentes dans ce domaine ont permis des avancées significatives dans la formulation des problèmes ainsi que dans la conception et l'analyse d'algorithmes. Dans cette étude, nous nous intéressons au problème de la logistique. Notre attention se porte en particulier sur un cas des réseaux de télécommunication, 2ECON-NDPR, et sur la façon de créer des designs d'une manière intelligente pour assurer la vitalité et la durabilité de la circulation de l'information. En outre. Nous choisissons les variantes problème de tournées de véhicules avec fenêtres de temps et problème de tournées de véhicules sélectives des familles VRP et OP respectivement. C'est dans ce cadre que s'inscrit cette thèse. La conception des solutions pour ces problèmes fait appel à la technique de programmation approchée connue pour sa rapidité de calcul. Il s’agit de Beam-search et de la recherche locale à grand voisinage. Nous présentons tout d’abord une étude détaillée des dernières problématiques précitées ainsi que différents types de méthodes de résolutions. Puis, nous exposons une méthode de recherche locale à grand voisinage adaptée pour la conception de réseau de survie avec relais, une proposition d’un algorithme de résolution approchée à trois phases pour le CVRPTW et, enfin, une proposition d'un algorithme de résolution approchée hybride pour le TOP. / The need to save time as well as minimize effort is part of the human condition and it has driven our though s from antiquity until these last few decades, now characterized by the emergence of a mix in all fields between rapidity of calculation and precision in the result. The vehicle routing problem and its extensions are an important field for theorists of these utilities for real-world applications. Recent research in the field has led to significant advantages in problem formulation and designing algorithm analyses. This study considers logistics problems. A particular locus was given to a certain case of telecommunications networks 2ECONNDPR, as well as the method of intelligently creating designs to ensure vitality and durability in information circulation. Furthermore, the study considered vehicle routing problems, with time windows and orienteering problems from the VRP and OP families, respectively. This is the framework for this thesis. Solutions to these problems use programming techniques known for their calculation speed, i .e ., Beam-search and very large-scale neighborhood searching. First, a detailed study is presented of these above mentioned problems, along with the various types or resolution methods. Next, a very large-scale neighborhood search method is presented, suited to the design of a survivable network with relay, a proposition for a three-stage heuristic for the capacitated vehicle routing problem with time windows and, finally, a proposition for a hybrid heuristic for the team orienteering problem.
86

Programação da produção em sistemas flowshop híbrido com buffers limitados / Production scheduling in hybrid flowshop with limited buffers

Lugo, Pedro Luis Miranda 12 September 2013 (has links)
Made available in DSpace on 2016-06-02T19:53:31Z (GMT). No. of bitstreams: 1 LUGO_Pedro_2013.pdf: 2147400 bytes, checksum: a0c7948826b7f243c447b99fd96c3388 (MD5) Previous issue date: 2013-09-12 / Financiadora de Estudos e Projetos / This research studies the hybrid flowshop scheduling problem. In this production configuration, we have a set of jobs that has to be processed in a set of stages. At every stage we have a set of parallel machines available to process the jobs. All jobs have to be processed following the same production flow, from the first to the last stage. Every job has to be processed on one machine at each stage and each machine can process at most one job at a time. Some constraints commonly found in real production systems as unrelated parallel machines, limited buffers, sequence-dependent setup times (both anticipatory and non-anticipatory), machine eligibility, transportation times and release times for machines are also taken into account. The optimization criterion is the makespan, whose minimization is related to the efficient use of production resources. A mixed integer programming model is proposed and solved by the commercial solver CPLEX. The computational evaluation results indicate that the model is suitable just to solve instances up to nine jobs and five stages. Therefore, to solve larger instances (50-100 jobs), several heuristics and an iterated local search (ILS) algorithm are proposed and evaluated computationally. The results indicate that the ILS is able to obtain good quality solutions in short computation times. / Este trabalho estuda o problema de programação da produção em sistemas Flowshop híbrido. Nesta configuração de produção há um conjunto de tarefas que deve ser processado em um conjunto de estações, nas quais um determinado número de máquinas paralelas encontra-se disponível para o processamento das tarefas. Todas as tarefas devem ser processadas seguindo o mesmo fluxo de produção, desde a primeira até a última estação. Cada tarefa deve ser processada em uma máquina de cada estação e cada máquina pode processar, no máximo, uma tarefa por vez. Algumas restrições comumente encontradas em sistemas de produção reais, como máquinas paralelas não relacionadas, buffers limitados, tempos de preparação dependentes da sequência (antecipatórios e não antecipatórios), elegibilidade de máquinas, tempos de transporte e tempos de liberação das máquinas, também são consideradas. O critério de otimização é o makespan, cuja minimização está diretamente relacionada com a utilização eficiente dos recursos de produção. Um modelo de programação inteira mista é proposto e resolvido através do solver comercial CPLEX. Os resultados da avaliação computacional indicam que o modelo é viável somente para resolver instâncias de até nove tarefas e cinco estações. Desta forma, para resolver instâncias de maior tamanho (50-100 tarefas), várias heurísticas e uma meta-heurística de busca local iterada (ILS, Iterated Local Search) são propostas e avaliadas computacionalmente. Os resultados indicam que o ILS é capaz de obter soluções de boa qualidade em curtos tempos computacionais.
87

Uma abordagem heurística para um problema de rebalanceamento estático em sistemas de compartilhamento de bicicletas

Albuquerque, Fabio Cruz Barbosa de 20 May 2016 (has links)
Submitted by Fernando Souza (fernandoafsou@gmail.com) on 2017-08-15T11:46:12Z No. of bitstreams: 1 arquivototal.pdf: 884446 bytes, checksum: 92314027dddef8365b4a2e655b65bd78 (MD5) / Made available in DSpace on 2017-08-15T11:46:13Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 884446 bytes, checksum: 92314027dddef8365b4a2e655b65bd78 (MD5) Previous issue date: 2016-05-20 / The Static Bike Rebalancing Problem (SBRP) is a recent problem motivated by the task of repositioning bikes among stations in a self-service bike-sharing systems. This problem can be seen as a variant of the one-commodity pickup and delivery vehicle routing problem, where multiple visits are allowed to be performed at each station, i.e., the demand of a station is allowed to be split. Moreover, a vehicle may temporarily drop its load at a station, leaving it in excess or, alternatively, collect more bikes (even all of them) from a station, thus leaving it in default. Both cases require further visits in order to meet the actual demands of such station. This work deals with a particular case of the SBRP, in which only a single vehicle is available and the objective is to nd a least-cost route that meets the demand of all stations and does not violate the minimum (zero) and maximum (vehicle capacity) load limits along the tour. Therefore, the number of bikes to be collected or delivered at each station should be appropriately determined in order to respect such constraints. This is a NP-Hard problem since it contains other NP-Hard problems as special cases, hence, using exact methods to solve it is intractable for larger instances. Several methods have been proposed by other authors, providing optimal values for small to medium sized instances, however, no work has consistently solved instances with more than 60 stations. The proposed algorithm to solve the problem is an iterated local search (ILS) based heuristic combined with a randomized variable neighborhood descent (RVND) as local search procedure. The algorithm was tested on 980 benchmark instances from the literature and the results obtained are quite competitive when compared to other existing methods. Moreover, the method was capable of nding most of the known optimal solutions and also of improving the results on a number of open instances. / O Problema do Rebalanceamento Est atico de Bicicletas (Static Bike Rebalancing Problem, SBRP) e um recente problema motivado pela tarefa de reposicionar bicicletas entre esta c~oes em um sistema self-service de compartilhamento de bicicletas. Este problema pode ser visto como uma variante do problema de roteamento de ve culos com coleta e entrega de um unico tipo de produto, onde realizar m ultiplas visitas a cada esta c~ao e permitido, isto e, a demanda da esta c~ao pode ser fracionada. Al em disso, um ve culo pode descarregar sua carga temporariamente em uma esta c~ao, deixando-a em excesso, ou, de maneira an aloga, coletar mais bicicletas (at e mesmo todas elas) de uma esta c~ao, deixando-a em falta. Em ambos os casos s~ao necess arias visitas adicionais para satisfazer as demandas reais de cada esta c~ao. Este trabalho lida com um caso particular do SBRP, em que apenas um ve culo est a dispon vel e o objetivo e encontrar uma rota de custo m nimo que satisfa ca as demandas de todas as esta c~oes e n~ao viole os limites de carga m nimo (zero) e m aximo (capacidade do ve culo) durante a rota. Portanto, o n umero de bicicletas a serem coletadas ou entregues em cada esta c~ao deve ser determinado apropriadamente a respeitar tais restri c~oes. Trata-se de um problema NP-Dif cil uma vez que cont em outros problemas NP-Dif cil como casos particulares, logo, o uso de m etodos exatos para resolv^e-lo e intrat avel para inst^ancias maiores. Diversos m etodos foram propostos por outros autores, fornecendo valores otimos para inst^ancias pequenas e m edias, no entanto, nenhum trabalho resolveu de maneira consistente inst^ancias com mais de 60 esta c~oes. O algoritmo proposto para resolver o problema e baseado na metaheur stica Iterated Local Search (ILS) combinada com o procedimento de busca local variable neighborhood descent com ordena c~ao aleat oria (randomized variable neighborhood descent, RVND). O algoritmo foi testado em 980 inst^ancias de refer^encia na literatura e os resultados obtidos s~ao bastante competitivos quando comparados com outros m etodos existentes. Al em disso, o m etodo foi capaz de encontrar a maioria das solu c~oes otimas conhecidas e tamb em melhorar os resultados de inst^ancias abertas.
88

Reconfiguração de sistemas de distribuição de energia elétrica utilizando uma metodologia multipartida /

Cardona, Natalia Patiño January 2016 (has links)
Orientador: Rubén Augusto Romero Lázaro / Resumo: Este trabalho apresenta uma proposta baseada na metodologia multipartida para a resolução do Problema de Reconfiguração de Sistemas de Distribuição de Energia Elétrica, de natureza combinatória e modelado como um problema de Programação Não Linear Inteiro Misto. O objetivo principal deste trabalho é encontrar a topologia radial ótima para minimizar as perdas ativas dos sistemas de distribuição, e para isso é preciso, primeiramente, a resolução de um problema de fluxo de potência para sistemas fracamente malhados onde é calculada a potência aparente do sistema, a qual vai ser utilizada pelo algoritmo de Prim como o peso para a geração das soluções iniciais radiais de boa qualidade. Para implementar a metodologia proposta deve-se desenvolver também um algoritmo de fluxo de potência radial, utilizado para calcular tanto as perdas ativas do sistema (função objetivo do problema), como para verificar a factibilidade das propostas de solução. Nesta primeira etapa é feita uma variação aleatória dos pesos dos ramos, e são resolvidos tantos problemas de fluxo de potência radial quanto soluções aleatórias obtidas, para encontrar soluções de boa qualidade próximas ao ótimo. Finalmente, é feita uma busca local através da troca de ramos como tentativa para encontrar a solução ótima. As soluções obtidas pela metodologia proposta são obtidas através da programação de algoritmos implementados em linguagem C++. Os resultados obtidos mostram a eficiência da aplicação da metodologia, estes resul... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This work presents a proposal based on multi-start methodology for the solution of the distribution network reconfiguration problem, of combinatorial nature and modeled as a mixed-integer nonlinear programming problem. The main objective of this work is to find the optimal radial topology to minimize active power losses in distribution systems. This requires, at first, the resolution of a power flow problem for weakly meshed systems where the apparent power of the system is calculated, which will be used by the Prim algorithm as the weight for generating the radial initial good quality solution. To implement the proposed methodology is also developed a radial power flow algorithm, used to calculate both the active system losses (objective function of the problem) and to verify the feasibility of the proposed solutions. In this first stage is made a random variation of the weights of branches, and there are solved as many radial power flows as random solutions obtained, to find good quality solutions close to optimal. Finally, a local search is made by doing an exchange of branches as an attempt to find the optimal solution. The solutions obtained by the proposed method are acquired by programming algorithms implemented in C ++ language. The results show the effectiveness of the application of the methodology. These results were compared with those in the literature and those obtained by solving an optimization model solved by the commercial solver CPLEX. / Mestre
89

Efficient modularity density heuristics in graph clustering and their applications

Santiago, Rafael de January 2017 (has links)
Modularity Density Maximization is a graph clustering problem which avoids the resolution limit degeneracy of the Modularity Maximization problem. This thesis aims at solving larger instances than current Modularity Density heuristics do, and show how close the obtained solutions are to the expected clustering. Three main contributions arise from this objective. The first one is about the theoretical contributions about properties of Modularity Density based prioritizers. The second one is the development of eight Modularity Density Maximization heuristics. Our heuristics are compared with optimal results from the literature, and with GAOD, iMeme-Net, HAIN, BMD- heuristics. Our results are also compared with CNM and Louvain which are heuristics for Modularity Maximization that solve instances with thousands of nodes. The tests were carried out by using graphs from the “Stanford Large Network Dataset Collection”. The experiments have shown that our eight heuristics found solutions for graphs with hundreds of thousands of nodes. Our results have also shown that five of our heuristics surpassed the current state-of-the-art Modularity Density Maximization heuristic solvers for large graphs. A third contribution is the proposal of six column generation methods. These methods use exact and heuristic auxiliary solvers and an initial variable generator. Comparisons among our proposed column generations and state-of-the-art algorithms were also carried out. The results showed that: (i) two of our methods surpassed the state-of-the-art algorithms in terms of time, and (ii) our methods proved the optimal value for larger instances than current approaches can tackle. Our results suggest clear improvements to the state-of-the-art results for the Modularity Density Maximization problem.
90

A heuristic approach to supply chain network design in a multi-commodity four-echelon logistics system

Farias, Everton da Silveira January 2016 (has links)
Nesta tese propõe-se um método heurístico para o problema de Projeto de Rede da Cadeia de Suprimentos (Supply Chain Network Design) considerando vários aspectos de relevância prática, tais como: fornecedores e matérias-primas, localização e operação de instalações, atribuição de Centros de Distribuição (CD), e grande número de clientes e produtos. Uma eficiente abordagem heurística de duas fases é proposta para a obtenção de soluções viáveis para os problemas, que inicialmente é modelado como um Programa Linear Inteiro Misto (PLIM) de grande escala. Na fase de construção, uma estratégia de Linear Programming Rounding é aplicada para se obter os valores iniciais para as variáveis de localização inteira do modelo. Simultaneamente, um método Multi-start foi desenvolvido para gerar soluções iniciais diversificadas para cada nova iteração da heurística de Rounding. Na segunda fase, dois procedimentos de Busca Local foram desenvolvidos no sentido de melhorar a solução fornecida pelo método de Rounding. Implementamos duas diferentes abordagens de Busca Local: remoção-inserção e troca. Uma técnica de Busca Tabu para orientar o procedimento de Busca Local para explorar os diferentes espaços de soluções foi desenvolvida. As formulações e algoritmos foram implementados na linguagem C++ utilizando ferramentas de otimização da COIN-OR. O método de solução foi experimentado em instâncias geradas aleatoriamente, com tamanhos diferentes em termos do número de parâmetros, tais como o número de produtos, zonas de clientes, CDs e fábricas considerando um sistema logístico de quatro níveis. As implementações computacionais mostram que o método de solução proposto obteve resultados satisfatórios quando comparados com a literatura. Para validar este método heurístico também foi usado em um caso realista, com base em dados de uma empresa de borracha que está reestruturando sua cadeia de suprimentos devido ao projeto de uma nova uma nova fábrica e produção de novos produtos. A abordagem heurística proposta revelou-se adequada para aplicação prática em um caso real de uma indústria multicommodity em um contexto determinístico. / In this thesis we propose a heuristic method for the Supply Chain Network Design (SCND) problem considering several aspects of practical relevance: suppliers and raw materials, location and operation facilities, distribution center (DC) assignments, and large numbers of customers and products. An efficient two-phase heuristic approach is proposed for obtaining feasible solutions to the problems, which is initially modeled as a large-scale Mixed Integer Linear Program (MILP). In the construction phase, a linear programming rounding strategy is applied to obtain initial values for the integer location variables in the model. Simultaneously, a Multi-start method was developed to generate diversified initial solutions from each new iteration in the rounding heuristic. In the second phase, two Local Search procedures were developed towards to improve the solution provided by the rounding method. We implemented two different Local Search approaches: removal-insertion and exchange. A Tabu Search technique was developed to guide the Local Search procedure to explore the different spaces of solutions. The formulations and algorithms were implemented in C++ code language using the optimization engine COIN-OR. The solution method was experimented in randomly generated instances, with different sizes in terms of the number of parameters, such as number of products, customer zones, DCs, and factories considering a four-echelon logistic system. The computational implementations show that the solution method proposed obtained satisfactory results when compared to the literature review. To validate this heuristic method was also used in a realistic case, based on data from a rubber company that is restructuring its supply chain due to the overture of a new factory, producing new products. The proposed heuristic approach proved appropriate to practical application in a realistic case of a multi commodity industry in a deterministic context.

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