In this thesis the capacitated vehicle routing problem with time windows (VRPTW) is studied, where the objective is to serve a set of geographically dispersed customers with known demands and predefined time windows at the minimum cost. It is hard to find an optimal solution for the VRPTW even if the problem size is small. Therefore, many heuristic methods are developed to obtain near optimal solutions. In this study a local search algorithm is proposed for solving the VRPTW, which consist of route construction and route improvement phases. Computational experiments are conducted with Solomon (1987)&rsquo / s and Homberger and Gehring (1999)&rsquo / s problem sets in order to test the performance of the proposed algorithm. From the computational results encouraging results are obtained in terms of solution quality.

This thesis identifies some problems, the genetic algorithm (GA) is facing in the area of vehicle routing and proposes various methods to address those problems. Those problems arise from the unavailability of suitable chromosomal representation and evaluation schemes of GA for the Vehicle Routing Problem (VRP). The representation and evaluation schemes already in use have problems of high computational cost, illegal chromosomes (chromosomes not representing a legal tour) and wrong fitness assignment (fitness not truly representing chromosome genetic makeup). These problems are addressed by several proposed new schemes, namely the Self Imposed Constraints Evaluation scheme, the Contour and Reverse Contour Evaluation schemes and the Order Skipping Evaluation scheme, which are specifically tailored for various objectives, problems and situations. Apart from this, a methodology, which has previously being used in other meta-heuristics, is incorporated into GA i.e., the independent application of GA on various sub-localities of the problem. We call this GA, a Localized Genetic Algorithm (LGA). LGA is an iterative procedure between optimization and controlled de-optimization. The procedure of controlled de-optimization is also novel. It brings the solution into a new search space while controlling its cost effectively. LGA is introduced with various search techniques, i.e. intensive, extensive and selective, the use of which depends on the problem size and the availability of computational resources. Furthermore, search reduction techniques (Fitness Approximation Methods) are also introduced into the LGA, which has enabled the LGA to be applied to large scale problems. Due to the implementation of those proposals, LGA is the first GA-driven approach to be applied to very large scale CVRP problems of up to 1200 customers, i.e. datasets presented by Feiyue in 2005 and large scale VRPTW problems of up to 1000 customers, datasets presented by Gehring and Homberger in 1999. Lastly, a standard unit for computational comparison, i.e., Bellman's Evaluation Units BEUs, is also introduced to facilitate computational comparisons for future researchers. LGA has shown promising results on CVRP and VRPTW problems. It is flexible and also has the potential to be extended to not only other vehicle routing problems, but also to other ordering problems.

Control of complex systems satisfying rich temporal specification has become an increasingly important research area in fields such as robotics, control, automotive, and manufacturing. Popular specification languages include temporal logics, such as Linear Temporal Logic (LTL) and Computational Tree Logic (CTL), which extend propositional logic to capture the temporal sequencing of system properties. The focus of this dissertation is on the control of high-dimensional systems and on timed specifications that impose explicit time bounds on the satisfaction of tasks. This work proposes and evaluates methods and algorithms for synthesizing provably correct control policies that deal with the scalability problems. Ideas and tools from formal verification, graph theory, and incremental computing are used to synthesize satisfying control strategies. Finite abstractions of the systems are generated, and then composed with automata encoding the specifications. The first part of this dissertation introduces a sampling-based motion planning algorithm that combines long-term temporal logic goals with short-term reactive requirements. The specification has two parts: (1) a global specification given as an LTL formula over a set of static service requests that occur at the regions of a known environment, and (2) a local specification that requires servicing a set of dynamic requests that can be sensed locally during the execution. The proposed computational framework consists of two main ingredients: (a) an off-line sampling-based algorithm for the construction of a global transition system that contains a path satisfying the LTL formula, and (b) an on-line sampling-based algorithm to generate paths that service the local requests, while making sure that the satisfaction of the global specification is not affected. The second part of the dissertation focuses on stochastic systems with temporal and uncertainty constraints. A specification language called Gaussian Distribution Temporal Logic is introduced as an extension of Boolean logic that incorporates temporal evolution and noise mitigation directly into the task specifications. A sampling-based algorithm to synthesize control policies is presented that generates a transition system in the belief space and uses local feedback controllers to break the curse of history associated with belief space planning. Switching control policies are then computed using a product Markov Decision Process between the transition system and the Rabin automaton encoding the specification.The approach is evaluated in experiments using a camera network and ground robot. The third part of this dissertation focuses on control of multi-vehicle systems with timed specifications and charging constraints. A rich expressivity language called Time Window Temporal Logic (TWTL) that describes time bounded specifications is introduced. The temporal relaxation of TWTL formulae with respect to the deadlines of tasks is also discussed. The key ingredient of the solution is an algorithm to translate a TWTL formula to an annotated finite state automaton that encodes all possible temporal relaxations of the given formula. The annotated automata are composed with transition systems encoding the motion of all vehicles, and with charging models to produce control strategies for all vehicles such that the overall system satisfies the mission specification. The methods are evaluated in simulation and experimental trials with quadrotors and charging stations.

Este trabalho apresenta uma variação do problema de roteamento de veículos que permite o uso de veículos com múltiplos compartimentos. A necessidade de veículos com múltiplos compartimentos surge com frequência em aplicações práticas quando uma série de produtos, que possuem diferentes qualidades ou tipo, precisam ser transportados mas não podem ser misturados. Este problema é chamado na literatura de roteamento de veículos com múltiplos compartimentos (PRVMC). Nós propomos uma heurística busca tabu implementada em uma busca local iterada para resolver este problema. Experimentos foram feitos para avaliar a performance da busca tabu iterada e os resultados obtidos foram comparados com os resultados disponíveis na literatura. O algoritimo proposto é capaz de encontrar soluções melhores e em menos tempo de processamento que as heurísticas existentes. / We study a variant of the vehicle routing problem that allows vehicles with multiple compartments. The need for multiple compartments frequently arises in practical applications when there are several products of different quality or type, that must be kept or handled separately. The resulting problem is called the multi-compartment vehicle routing problem (MCVRP). We propose a tabu search heuristic and embed it into an iterated local search to solve the MCVRP. In several experiments we analyze the performance of the iterated tabu search and compare it with results from the literature. We find that it consistently produces solutions that are better than existing heuristic algorithms.

Este trabalho apresenta uma variação do problema de roteamento de veículos que permite o uso de veículos com múltiplos compartimentos. A necessidade de veículos com múltiplos compartimentos surge com frequência em aplicações práticas quando uma série de produtos, que possuem diferentes qualidades ou tipo, precisam ser transportados mas não podem ser misturados. Este problema é chamado na literatura de roteamento de veículos com múltiplos compartimentos (PRVMC). Nós propomos uma heurística busca tabu implementada em uma busca local iterada para resolver este problema. Experimentos foram feitos para avaliar a performance da busca tabu iterada e os resultados obtidos foram comparados com os resultados disponíveis na literatura. O algoritimo proposto é capaz de encontrar soluções melhores e em menos tempo de processamento que as heurísticas existentes. / We study a variant of the vehicle routing problem that allows vehicles with multiple compartments. The need for multiple compartments frequently arises in practical applications when there are several products of different quality or type, that must be kept or handled separately. The resulting problem is called the multi-compartment vehicle routing problem (MCVRP). We propose a tabu search heuristic and embed it into an iterated local search to solve the MCVRP. In several experiments we analyze the performance of the iterated tabu search and compare it with results from the literature. We find that it consistently produces solutions that are better than existing heuristic algorithms.

Orientador: Flávio Keidi Miyazawa / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Computação / Made available in DSpace on 2018-08-16T14:13:04Z (GMT). No. of bitstreams: 1 Azevedo_BrunoLuisPiresde_M.pdf: 1384772 bytes, checksum: 48aa7ca2380aaa03fd6375cb9b35aebc (MD5) Previous issue date: 2009 / Resumo: Nesta dissertação apresentamos um algoritmo exato para o Problema de Roteamento de Veículos Capacitados com Restrições Bidimensionais. Este combina o problema de carregar um conjunto de itens bidimensionais em veículos com o problema de minimizar o custo total de transporte. Existem várias aplicações práticas para este problema, dado que em muitas situações os itens não podem ser empilhados por diversas razões. Propomos um algoritmo exato baseado em uma abordagem branch-and-cut. Sete desigualdades válidas para o Problema de Roteamento de Veículos Capacitados foram adaptadas e utilizadas. As restrições de empacotamento são garantidas através de um algoritmo exato. Também apresentamos uma nova heurística de empacotamento bidimensional. Exploramos duas variantes do problema, as versões seqüencial e irrestrita. Para ambos os casos, consideramos os itens possuirem orientação fixa. Efetuamos testes computacionais e comparamos os resultados obtidos com a abordagem exata, para o caso seqüencial, apresentada por Iori, Salazar-González e Vigo. Observamos resultados satisfatórios e nove instâncias da literatura foram resolvidas à otimalidade pela primeira vez. Como o caso irrestrito ainda não havia sido abordado de modo exato, apresentamos também as soluções de cinqüenta instâncias nunca resolvidas à otimalidade / Abstract: We present an exact algorithm for the Vehicle Routing Problem with Two-dimensional Loading Constraints. This problem combines the problems of loading vehicles with two-dimensional items and minimizing transportation costs. It has many practical applications, since in many cases items can not be stacked on top of each other. We propose an exact algorithmbased on a branch-and-cut approach. Seven valid inequalities for the the Capacitated Vehicle Routing Problems were modified and used. The packing constraints are imposed by an exact algorithm. We also present a new heuristic for two-dimensional packing. We explored two variants of the problem, the sequential and the unrestricted cases. For both variants we assume the items to have fixed orientation. We performed computational tests and compared the results with the exact approach by Iori, Salazar-González and Vigo for the sequential case. We found the results to be satisfactory and nine instances from the literature were solved to optimality for the first time. Since the unrestricted case haven't been tested so far by an exact algorithm, we also present the solutions for fifty instances never solved to optimality before / Mestrado / Teoria da Computação / Mestre em Ciência da Computação

Orientador: Cid Carvalho de Souza / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Computação / Made available in DSpace on 2018-08-19T00:16:31Z (GMT). No. of bitstreams: 1 Zilli_PetersonKatagiri_M.pdf: 1307926 bytes, checksum: 5fe0ddfca7cce84d9e26b66106d61e8b (MD5) Previous issue date: 2011 / Resumo: O Problema de Roteamento de Veículos (VRP, em inglês) foi proposto por Dantzig e Ramser em 1959 e, desde então, um grande número de artigos foi dedicado à solução de suas variantes. O problema original consiste em determinar rotas otimais que serão usadas por veículos de capacidade limitada para servirem a um conjunto de clientes. Neste trabalho focamos o estudo e a implementação dos modelos chamados de "ricos" na literatura, os quais englobam variantes complexas do VRP e conseguem representar situações mais próximas dos problemas logísticos encontrados em sistemas de distribuição reais. A principal motivação para esta pesquisa é uma aplicação prática referente ao problema de roteamento dos ônibus fretados pela UNICAMP para o transporte de seus funcionários, que se caracteriza como um modelo rico. O objetivo final é a otimização de tal processo através da minimização da distância total percorrida ou do número de veículos empregados, com a consequente redução dos gastos incorridos pela Universidade. Portanto, além do seu aspecto científico, esta dissertação produz resultados com chances reais de trazer benefícios à administração de uma instituição pública de ensino. Para que isto venha a ocorrer, as heurísticas desenvolvidas foram inseridas em um sistema de informações geográficas, que será usado pela universidade no processo de criação e otimização das rotas a serem licitadas publicamente / Abstract: The Vehicle Routing Problem (VRP) was first proposed by Dantzig and Ramser in 1959 and, since then, a large number of papers has been devoted to the solution of its variants. The original problem consists in determining an optimal set of routes to be used by vehicles of limited capacity that serve a set of customers. In this paper we focus on the study and implementation of models called "rich" in the literature, which include complex variants of the VRP that represent situations closer to the logistical problems encountered in real distribution systems. The main motivation for this research is a practical problem concerning the routing of buses chartered by UNICAMP for transporting a part of its employees, which is characterized as a rich model. The goal is to optimize this process by minimizing the total travel distance or the number of vehicles used, with a consequent reduction of the expenses incurred by the University. Therefore, in addition to its scientific aspect, this dissertation gives results with real chances to benefit the administration of a public university. For this to happen, the heuristics developed were entered into a geographic information system, which will be used by the university in the process of creation and optimization of routes to be publicly auctioned / Mestrado / Pesquisa Operacional / Mestre em Ciência da Computação

[pt] Como em toda grande empresa da indústria de óleo e gás, fortemente integrada e altamente rentável, várias são as oportunidades de buscar e encontrar processos logísticos com reais possibilidades de otimização e melhoria. Neste tipo de companhia, encontramos diversas cadeias de suprimento subjacentes ao processo, que por seu porte e complexidade, seriam consideradas principais em diversas outras indústrias ou ramos de serviços. Neste contexto, a presente dissertação se propõe a analisar as etapas e percalços para implantação e manutenção de um software de roteirização como ferramenta para planejamento de frota e rota de transporte de funcionários em regime de turno de uma refinaria. O cenário escolhido para o piloto é uma refinaria de grande porte do estado do Rio de Janeiro. O estudo revisa a bibliografia existente, descreve as principais etapas de coleta e tratamento de dados, mede através do software TRANSCAD as distâncias das rotas propostas e verifica se o potencial ganho obtido em relação à solução em análise justificaria a aquisição de uma ferramenta para este fim. / [en] As in many big oil and gas companies, there are a lot of opportunities to search and find logistics processes with real possibilities for optimization and improvement. In this kind of company there are some supply chains, that are not core chains wich could be considered as main chains in many other industries or service areas due to their size and complexity. Regarding that issue, the present work proposes to analyze the steps and problems related to launching and maintaining a routing software as a solution for vehicle fleet planning and refinery s employees transportation routing. A big refinery placed in Rio de Janeiro state is the chosen scenario. This study reviews the present literature on the theme, describes the main steps on this research and data treatment, uses the software TRANSCAD to measure de length of the proposed routes and finds out if the potential gain with the software solution justifies the acquisition of this tool.

L'étude menée dans cette thèse porte sur la logistique multi-objectif des déchets ménagers. Elle s'est déroulée en partenariat avec une collectivité locale, la Communauté d'Agglomération du Muretain (CAM) située près de Toulouse qui nous a fournit les problématiques et les différents paramètres à prendre en compte pour le développement de l'étude. Cette thèse s'est déroulée au sein de deux équipes, dans l'équipe de Production Automatisé (PA) du Laboratoire de Génie de Production (LGP) de Tarbes ainsi que dans l'équipe de Modélisation d'Optimisation et de Gestion Intégrée de Systèmes d'Activités (MOGISA) du Laboratoire d'Analyse et d'Architecture des Systèmes (LAAS) de Toulouse. Il y a une trentaine d'année, le traitement des déchets se résumait à une simple mise en décharge. Depuis une conscience collective des problématiques environnementales a placé le traitement des déchets au cœur des préoccupations publiques. La gestion qui est faite des déchets ménagers constitue un enjeu environnemental, économique, social et de citoyennetés majeures, directement lié aux modes de consommation et à la société plus généralement. En France, les municipalités ou les collectivités locales, regroupant plusieurs municipalités, ont en charge de collecter et de convoyer les déchets vers leur lieu de traitement. Dans l'étude proposée, nous allons nous intéresser à la partie logistique, et plus précisément à la collecte et au transport des déchets ménagers et assimilés jusqu’à leur point de décharge (déchetteries, centre de transfert ou centre de traitement directement). Le but étant d’optimiser le transport de déchets tout en gardant une bonne qualité de service. Les enjeux mis en relief pour cette problématique sont les enjeux classiques imposés par toute étude visant à améliorer un service publique : un enjeu économique classique (minimiser les coûts de collecte et de transport), un enjeu environnemental évident (diminuer l'impact environnemental), un enjeu de qualité (satisfaire au mieux les usagers) et enfin un enjeu social (satisfaire les conditions de travail des employés). On va donc ici se concentrer sur l’aspect opérationnel journalier de la gestion. Lorsque celui-ci concerne une planification de trajet pour plusieurs véhicules en même temps qui doivent chacun faire leur circuit en livrant une certaine quantité de produit à chaque client cela se nomme le problème de tournées de véhicules (Vehicle Routing Problem). Ce problème pratique est souvent étudié pour des cas réels et se complexifie avec l’ajout de nombreux paramètres et contraintes, comme par exemple des contraintes d'horaire de passage sur certaines parties du réseau ; ou encore par l'ajout de plusieurs critères à optimiser en mêmes temps, comme par exemple les critères représentant les coûts et ceux représentant l'équilibrage de tournées, etc. / The study in this thesis focuses on the multipurpose logistics of household waste.

This thesis is continuation of the bachelor thesis "Model of delivery routes and placement logistics centers with opportunities of their optimization". It is about distribution problems and specifically a vehicle routing problem. The aim of this thesis is finding a solution of the vehicle routing problem which will be used repeatedly in the firm. The main task is achieving the lowest costs (total kilometers) with maximum utilization of vehicle capacity; in such conditions that all requirements of logistics centers will be satisfied and maximal capacity of vehicle will be tolerated. For calculation was used a solver Gurobi 6.0.3 in system MPL for Windows 4.2, which won't, however, provide the optimal solution and problem solving takes too long time. Next for calculation was used heuristics insert method and is written by VBA (Visual Basic for Applications) in MS Excel. Finally, there is a comparison of these methods with the original solution of the vehicle routing plan and solution of the bachelor thesis. Then the computational experiment was done, which tested effect to result, if other distribution center (starting point) will be bulit. The computational experiment was consist from heuristic insert method, solver Gurobi and heuristic saving algorithm from bachelor thesis.