• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 19
  • 17
  • 10
  • 1
  • Tagged with
  • 53
  • 53
  • 16
  • 13
  • 10
  • 9
  • 9
  • 9
  • 9
  • 8
  • 8
  • 8
  • 8
  • 8
  • 7
  • 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.
11

A New Approach for Solving the Disruption in Vehicle Routing Problem During the Delivery : A Comparative Analysis of VRP Meta-Heuristics

Kaja, Sai Chandana January 2020 (has links)
Context. The purpose of this research paper is to describe a new approach for solving the disruption in the vehicle routing problem (DVRP) which deals with the disturbance that will occur unexpectedly within the distribution area when executing the original VRP plan. The paper then focuses further on the foremost common and usual problem in real-time scenarios i.e., vehicle-breakdown part. Therefore, the research needs to be accomplished to deal with these major disruption in routing problems in transportation. Objectives. The study first investigates to find suitable and efficient metaheuristic techniques for solving real-time vehicle routing problems than an experiment is performed with the chosen algorithms which might produce near-optimal solutions. Evaluate the performance of those selected algorithms and compare the results among each other. Methods. To answer research questions, firstly, a literature review has been performed to search out suitable meta-heuristic techniques for solving vehicle routing problems. Then based on the findings an experiment is performed to evaluate the performance of selected meta-heuristic algorithms. Results. Results from the literature review showed that the meta-heuristic approaches such as. Tabu Search, Ant Colony Optimization, and Genetic Algorithmare suitable and efficient algorithms for solving real-time vehicle routing problems. The performance of those algorithms has been calculated and compared with one another with standard benchmarks. Conclusions. The performance of a Tabu Search algorithm is best among the other algorithms, followed by Ant Colony Optimization and Genetic Algorithm. Therefore, it has been concluded that the Tabu Search is the best algorithm for solving real-time disruption problems in VRP. The results are similar to the performance comparison of the selected algorithms and standard benchmarks are presented within the research.
12

A matheuristic approach for solving the high school timetabling problem / Uma abordagem matheurística para resolver o problema de geração de quadros de horários escolares do ensino médio

Dornelles, Arton Pereira January 2015 (has links)
A geração de quadros de horários escolares é um problema clássico de otimização que tem sido largamente estudado devido a sua importâncias prática e teórica. O problema consiste em alocar um conjunto de aulas entre professor-turma em períodos de tempo pré-determinados, satisfazendo diferentes tipos de requisitos. Devido a natureza combinatória do problema, a resolução de instâncias médias e grandes torna-se uma tarefa desafiadora. Quando recursos são escassos, mesmo uma solução factível pode ser difícil de ser encontrada. Várias técnicas tem sido propostas na literatura científica para resolver o problema de geração de quadros de horários escolares, no entanto, métodos robustos ainda não existem. Visto que o uso de métodos exatos, como por exemplo, técnicas de programação matemática, não podem ser utilizados na prática, para resolver instâncias grandes da realidade, meta-heurísticas e meta-heurísticas híbridas são usadas com frequência como abordagens de resolução. Nesta pequisa, são desenvolvidas técnicas que combinam programação matemática e heurísticas, denominadas mateheurísticas, para resolver de maneira eficiente e robusta algumas variações de problemas de geração de quadros de horários escolares. Embora neste trabalho sejam abordados problemas encontrados no contexto de instituições brasileiras, os métodos propostos também podem ser aplicados em problemas similares oriundo de outros países. / The school timetabling is a classic optimization problem that has been extensively studied due to its practical and theoretical importance. It consists in scheduling a set of class-teacher meetings in a prefixed period of time, satisfying requirements of different types. Given the combinatorial nature of this problem, solving medium and large instances of timetabling to optimality is a challenging task. When resources are tight, it is often difficult to find even a feasible solution. Several techniques have been developed in the scientific literature to tackle the high school timetabling problem, however, robust solvers do not exist yet. Since the use of exact methods, such as mathematical programming techniques, is considered impracticable to solve large real world instances, metaheuristics and hybrid metaheuristics are the most used solution approaches. In this research we develop techniques that combine mathematical programming and heuristics, so-called matheuristics, to solve efficiently and in a robust way some variants of the high school timetabling problem. Although we pay special attention to problems arising in Brazilian institutions, the proposed methods can also be applied to problems from different countries.
13

Optimisation et simulation de la massification du transport multimodal de conteneurs / Optimization and Simulation of Consolidated Intermodal Transport

Rouky, Naoufal 29 October 2018 (has links)
Les ports maritimes se confrontent à des exigences rigoureuses imposées par l'évolution de la taille de la flotte mondiale des porte-conteneurs et des zones de stockage qui arrivent à des niveaux de saturation élevés. Pour répondre à ces défis, plusieurs ports ont décidé de créer des terminaux multimodaux qui jouent le rôle de méga-hubs pour les terminaux maritimes, en vue de libérer les zones de stockage de ces terminaux, de développer la part du transport massifié de conteneurs et de réduire les émissions des gaz à effet de serre en utilisant des modes alternatifs à la route. Néanmoins, la gestion de ces nouveaux schémas logistiques est laborieuse. Cela s’explique par plusieurs facteurs, entre autres, la nature dynamique et distribuée de ces systèmes, la diversité des opérations et le manque des informations nécessaires au contrôle de flux. La finalité de cette thèse est de développer des approches capables de répondre aux besoins des opérateurs portuaires dans un terminal multimodal, avec prise en compte des différentes sources d’incertitudes. Deux problèmes d'optimisation sont principalement considérés dans cette thèse, à savoir : l'optimisation de tournées de navettes ferroviaires (The Rail Shuttle Routing Problem) et l'ordonnancement de grues de quai (The Quay Crane Scheduling Problem). En vue d'aborder la complexité et l’aspect incertain de ces problèmes, nous proposerons des modélisations mathématiques, ainsi que des approches de résolution basées sur l’optimisation par colonies de fourmis, l’optimisation robuste et le couplage Simulation-Optimisation. Les différents tests numériques effectués ont prouvé l’efficacité des algorithmes proposés et leur robustesse. / Today, seaports face increasingly stringent requirements imposed by the considerable growth of goods transited by sea. Indeed, the organization of the port sector has evolved rapidly and has caused several negative impacts, including pollution and congestion of terminals, which constitute today the major concerns of port operators. To address those challenges, several ports have decided to build multimodal terminals that act as mega-hubs for maritime terminals, in order to free the storage areas on the maritime terminals, to promote the use of consolidated container modes of transfer and to reduce greenhouse gas emissions by using alternative modes to the road. Nevertheless, the management of these new logistic systems is laborious. This is due to several factors, including the dynamic and distributed nature of these systems, the variety of operations, and the lack of information needed to control flow. The aim of this thesis is to develop approaches capable of meeting the needs of port operators in a multimodal terminal, taking into account the different sources of uncertainty. Two optimization problems are mainly considered in this thesis, namely : the Rail Shuttle Routing Problem(RSRP) and the Quay Crane Scheduling Problem(QCSP). To address the complexity and uncertainties of these problems, we propose new mathematical models, as well as some heuristics approaches based on ant colony optimization, robust optimization and Simulation-Optimization. The various numerical tests carried out proved the effectiveness and the robustness of the proposed algorithms.
14

An Adaptive Simulated Annealing Method For Assembly Line Balancing And A Case Study

Guden, Huseyin 01 August 2006 (has links) (PDF)
Assembly line balancing problem is one of the most studied NP-Hard problems. NP-Hardness leads us to search for a good solution instead of the optimal solution especially for the big-size problems. Meta-heuristic algorithms are the search methods which are developed to find good solutions to the big-size and combinatorial problems. In this study, it is aimed at solving the multi-objective multi-model assembly line balancing problem of a company. A meta-heuristic algorithm is developed to solve the deterministic assembly line balancing problems. The algorithm developed is tested using the test problems in the literature and the the real life problem of the company as well. The results are analyzed and found to be promising and a solution is proposed for the firm.
15

A matheuristic approach for solving the high school timetabling problem / Uma abordagem matheurística para resolver o problema de geração de quadros de horários escolares do ensino médio

Dornelles, Arton Pereira January 2015 (has links)
A geração de quadros de horários escolares é um problema clássico de otimização que tem sido largamente estudado devido a sua importâncias prática e teórica. O problema consiste em alocar um conjunto de aulas entre professor-turma em períodos de tempo pré-determinados, satisfazendo diferentes tipos de requisitos. Devido a natureza combinatória do problema, a resolução de instâncias médias e grandes torna-se uma tarefa desafiadora. Quando recursos são escassos, mesmo uma solução factível pode ser difícil de ser encontrada. Várias técnicas tem sido propostas na literatura científica para resolver o problema de geração de quadros de horários escolares, no entanto, métodos robustos ainda não existem. Visto que o uso de métodos exatos, como por exemplo, técnicas de programação matemática, não podem ser utilizados na prática, para resolver instâncias grandes da realidade, meta-heurísticas e meta-heurísticas híbridas são usadas com frequência como abordagens de resolução. Nesta pequisa, são desenvolvidas técnicas que combinam programação matemática e heurísticas, denominadas mateheurísticas, para resolver de maneira eficiente e robusta algumas variações de problemas de geração de quadros de horários escolares. Embora neste trabalho sejam abordados problemas encontrados no contexto de instituições brasileiras, os métodos propostos também podem ser aplicados em problemas similares oriundo de outros países. / The school timetabling is a classic optimization problem that has been extensively studied due to its practical and theoretical importance. It consists in scheduling a set of class-teacher meetings in a prefixed period of time, satisfying requirements of different types. Given the combinatorial nature of this problem, solving medium and large instances of timetabling to optimality is a challenging task. When resources are tight, it is often difficult to find even a feasible solution. Several techniques have been developed in the scientific literature to tackle the high school timetabling problem, however, robust solvers do not exist yet. Since the use of exact methods, such as mathematical programming techniques, is considered impracticable to solve large real world instances, metaheuristics and hybrid metaheuristics are the most used solution approaches. In this research we develop techniques that combine mathematical programming and heuristics, so-called matheuristics, to solve efficiently and in a robust way some variants of the high school timetabling problem. Although we pay special attention to problems arising in Brazilian institutions, the proposed methods can also be applied to problems from different countries.
16

Metaheurística para o Problema de Planejamento de Redes de Transmissão de Energia Elétrica com Redimensionamento / Metaheuristics for the transmission expansion planning problem with redesign

Pedro Henrique González Silva 23 March 2012 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Com o passar do tempo, a demanda elétrica de diversas áreas varia tornando necessária a construção de novos geradores elétricos e a expansão da rede de transmissão de energia elétrica. Nesta dissertação, focamos no problema de expansão da rede de transmissão, assumindo que novos geradores estão construídos para suprir as novas demandas. Essa expansão exige altos investimentos que precisam ser cuidadosamente planejados. O problema pode ser modelado como um problema de otimização não linear inteira mista e pertence à classe dos problemas NP-difíceis. Desta forma, uma abordagem heurística pode ser adequada para a sua solução pois pode vir a fornecer boas soluções em tempo computacional aceitável. Esta dissertação se propõe a apresentar um estudo do problema de planejamento da expansão de redes de transmissão de energia elétrica estático e multiestágio. Mostramos o que já existe na literatura para o que é chamado de problema sem redimensionamento e as inovações feitas por nós para o problema com redimensionamento. Quanto aos métodos de solução, utilizamos a metaheurística GRASP para o problema estático e combinamos o GRASP com o procedimento Backward-Forward quando falamos em problema multiestágio. Nesta dissertação comparamos os resultados computacionais obtidos com resultados encontrados na literatura. / At times, the electrical load in diferent areas varies, claiming the construction of new electric generators and the expansion of the electrical transmission network. In this dissertation we focus on the transmission expansion planning problem, assuming that new generators are built to meet the new demands. This expansion requires large investments, which need to be carefully planned. This problem can be modeled as a mixed nonlinear programming problem, considered to be a NP-hard problem. Therefore a heuristic approach may be appropriate for its solution because it might be able to provide good solutions in satisfactory computational time. This dissertation intends to present a study of both the static and multistage transmission expansion planning problem. We present first a review of the most interesting works found in the technical literature. Then, we present metaheuristics for the static and multistage problems with re-design. These etaheuristics extend known algorithms for the problems without re-design. For the static problem, we extend a GRASP procedure and for the multistage problem, we embed the GRASP (or an exact method) into a backward-forward algorithm. We test our algorithms on real-based power transmission networks and compare them to the results found in the litterature.
17

Metaheurística para o Problema de Planejamento de Redes de Transmissão de Energia Elétrica com Redimensionamento / Metaheuristics for the transmission expansion planning problem with redesign

Pedro Henrique González Silva 23 March 2012 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Com o passar do tempo, a demanda elétrica de diversas áreas varia tornando necessária a construção de novos geradores elétricos e a expansão da rede de transmissão de energia elétrica. Nesta dissertação, focamos no problema de expansão da rede de transmissão, assumindo que novos geradores estão construídos para suprir as novas demandas. Essa expansão exige altos investimentos que precisam ser cuidadosamente planejados. O problema pode ser modelado como um problema de otimização não linear inteira mista e pertence à classe dos problemas NP-difíceis. Desta forma, uma abordagem heurística pode ser adequada para a sua solução pois pode vir a fornecer boas soluções em tempo computacional aceitável. Esta dissertação se propõe a apresentar um estudo do problema de planejamento da expansão de redes de transmissão de energia elétrica estático e multiestágio. Mostramos o que já existe na literatura para o que é chamado de problema sem redimensionamento e as inovações feitas por nós para o problema com redimensionamento. Quanto aos métodos de solução, utilizamos a metaheurística GRASP para o problema estático e combinamos o GRASP com o procedimento Backward-Forward quando falamos em problema multiestágio. Nesta dissertação comparamos os resultados computacionais obtidos com resultados encontrados na literatura. / At times, the electrical load in diferent areas varies, claiming the construction of new electric generators and the expansion of the electrical transmission network. In this dissertation we focus on the transmission expansion planning problem, assuming that new generators are built to meet the new demands. This expansion requires large investments, which need to be carefully planned. This problem can be modeled as a mixed nonlinear programming problem, considered to be a NP-hard problem. Therefore a heuristic approach may be appropriate for its solution because it might be able to provide good solutions in satisfactory computational time. This dissertation intends to present a study of both the static and multistage transmission expansion planning problem. We present first a review of the most interesting works found in the technical literature. Then, we present metaheuristics for the static and multistage problems with re-design. These etaheuristics extend known algorithms for the problems without re-design. For the static problem, we extend a GRASP procedure and for the multistage problem, we embed the GRASP (or an exact method) into a backward-forward algorithm. We test our algorithms on real-based power transmission networks and compare them to the results found in the litterature.
18

A matheuristic approach for solving the high school timetabling problem / Uma abordagem matheurística para resolver o problema de geração de quadros de horários escolares do ensino médio

Dornelles, Arton Pereira January 2015 (has links)
A geração de quadros de horários escolares é um problema clássico de otimização que tem sido largamente estudado devido a sua importâncias prática e teórica. O problema consiste em alocar um conjunto de aulas entre professor-turma em períodos de tempo pré-determinados, satisfazendo diferentes tipos de requisitos. Devido a natureza combinatória do problema, a resolução de instâncias médias e grandes torna-se uma tarefa desafiadora. Quando recursos são escassos, mesmo uma solução factível pode ser difícil de ser encontrada. Várias técnicas tem sido propostas na literatura científica para resolver o problema de geração de quadros de horários escolares, no entanto, métodos robustos ainda não existem. Visto que o uso de métodos exatos, como por exemplo, técnicas de programação matemática, não podem ser utilizados na prática, para resolver instâncias grandes da realidade, meta-heurísticas e meta-heurísticas híbridas são usadas com frequência como abordagens de resolução. Nesta pequisa, são desenvolvidas técnicas que combinam programação matemática e heurísticas, denominadas mateheurísticas, para resolver de maneira eficiente e robusta algumas variações de problemas de geração de quadros de horários escolares. Embora neste trabalho sejam abordados problemas encontrados no contexto de instituições brasileiras, os métodos propostos também podem ser aplicados em problemas similares oriundo de outros países. / The school timetabling is a classic optimization problem that has been extensively studied due to its practical and theoretical importance. It consists in scheduling a set of class-teacher meetings in a prefixed period of time, satisfying requirements of different types. Given the combinatorial nature of this problem, solving medium and large instances of timetabling to optimality is a challenging task. When resources are tight, it is often difficult to find even a feasible solution. Several techniques have been developed in the scientific literature to tackle the high school timetabling problem, however, robust solvers do not exist yet. Since the use of exact methods, such as mathematical programming techniques, is considered impracticable to solve large real world instances, metaheuristics and hybrid metaheuristics are the most used solution approaches. In this research we develop techniques that combine mathematical programming and heuristics, so-called matheuristics, to solve efficiently and in a robust way some variants of the high school timetabling problem. Although we pay special attention to problems arising in Brazilian institutions, the proposed methods can also be applied to problems from different countries.
19

Coopération méta heuristique et logique floue pour le dimensionnement d'une installation hybride / Meta heuristics cooperation and fuzzy logic for the design of a hybrid system

Ben Jemaa, Abdelhak 12 December 2015 (has links)
Cette thèse propose la méthodologie de dimensionnement optimal pour optimiser la configuration de système d'énergie hybride. Pour cela, nous utilisons une approche pour la génération de base de règles floues et une optimisation automatiques au moyen d'algorithme génétique et d'un PSO adaptés avec le floue. Ces algorithmes nous permet d'obtenir le nombre optimal de panneaux photovoltaïques, d'éoliennes et des batteries, minimisant le coût total du système et garantissant la disponibilité permanente de l'électricité pour couvrir les besoins énergétiques. L'historique horaire de vitesse du vent, d’ensoleillement, sont utilisés pour modéliser la production des éoliennes, la production photovoltaïque et de charge. Le coût total est la fonction objective et la taille technique est une contrainte. / This thesis proposes the optimum sizing methodology to optimize the configuration of hybrid energy system. For this, we use an approach for automatic fuzzy rule base generation and optimization by means of Fuzzy-Adaptive Genetic Algorithm and fuzzy adaptive PSO. This Algorithms allows us to obtain the optimal number of photovoltaic panels, wind turbines and storages units, ensuring the minimal global high efficiency system total cost and guaranteeing the permanent availability of energy to cover the load energy requirements. Historical hourly wind speed, solar irradiance and load data are used to stochastically model the wind turbines, photovoltaic generation and load. The total cost is the objective function and the technical size is a constraint.
20

Simulation-based optimization for production planning : integrating meta-heuristics, simulation and exact techniques to address the uncertainty and complexity of manufacturing systems

Diaz Leiva, Juan Esteban January 2016 (has links)
This doctoral thesis investigates the application of simulation-based optimization (SBO) as an alternative to conventional optimization techniques when the inherent uncertainty and complex features of real manufacturing systems need to be considered. Inspired by a real-world production planning setting, we provide a general formulation of the situation as an extended knapsack problem. We proceed by proposing a solution approach based on single and multi-objective SBO models, which use simulation to capture the uncertainty and complexity of the manufacturing system and employ meta-heuristic optimizers to search for near-optimal solutions. Moreover, we consider the design of matheuristic approaches that combine the advantages of population-based meta-heuristics with mathematical programming techniques. More specifically, we consider the integration of mathematical programming techniques during the initialization stage of the single and multi-objective approaches as well as during the actual search process. Using data collected from a manufacturing company, we provide evidence for the advantages of our approaches over conventional methods (integer linear programming and chance-constrained programming) and highlight the synergies resulting from the combination of simulation, meta-heuristics and mathematical programming methods. In the context of the same real-world problem, we also analyse different single and multi-objective SBO models for robust optimization. We demonstrate that the choice of robustness measure and the sample size used during fitness evaluation are crucial considerations in designing an effective multi-objective model.

Page generated in 0.0686 seconds