An extensive English language bibliography on graph theory and its applications

Bibliography on graph theory and its application

Arbeitsbericht Nr. 2006-05, November 2006

Ilmenauer Beiträge zur Wirtschaftsinformatik Nr. 2006-05 / Technische Universität Ilmenau, Fakultät für Wirtschaftswissenschaften, Institut für Wirtschaftsinformatik, ISSN 1861-9223 ISBN 3-938940-06-

Using group role assignment to solve Dynamic Vehicle Routing Problem

The Dynamic Vehicle Routing Problem (DVRP) is a more complex problem than the traditional Vehicle Routing Problem (VRP) in the combinatorial optimization of operations research. With more degrees of freedom, DVRP introduces new challenges while judging the merit of a given route plan. This thesis utilized the time slice strategy to solve dynamic and deterministic routing problems. Based on Group Role Assignment (GRA) and two different routing methods (Modified Insertion heuristic routing and Modified Composite Pairing Or-opt routing), a new ridesharing system has been designed to provide services in the real world. Simulation results are presented in this thesis. A qualitative comparison has been made to outline the advantages and performance of our solution framework. From the numerical results, the proposed method has a great potential to put into operation in the real world and provides a new transit option for the public.Master of Science (MSc) in Computational Scienc

Optimisation de la planification des cueillettes d'huiles usagées

Le but de l’étude présentée dans ce mémoire est d’adapter les méthodes de résolutions des problèmes de tournée de véhicule avec gestion de stock à un problème concret de collecte d’huiles usagées au Québec. Cette étude a pour objectif final d’optimiser le processus de collecte d’une grande entreprise du secteur de l’environnement. Ce type de problème est souvent résolu avec des méthodes exactes sur des problèmes de petites dimensions. Cependant, pour les problèmes de grande taille, les méthodes heuristiques sont plus souvent employées. Toutefois, dans cette étude, nous nous appuierons sur des méthodes exactes afin de conserver une démarche de résolution proche de la logique utilisée par l’entreprise bien que le nombre de clients à gérer soit de l’ordre d’une dizaine de milliers. L’étude s’articule autour d’une phase d’étude statistique de données historiques, de la création de différents modèles et de leur automatisation en vue de fournir des solutions viables à ce problème

Algoritmos heurísticos de cobertura de arcos

Tese (doutorado) - Universidade Federal de Santa Catarina. Centro Tecnológico. Programa de Pós-Graduação em Engenharia de ProduçãoNos problemas de roteamento o objetivo é determinar um circuito de custo mínimo que cobre um dado conjunto de arcos ou nós de um grafo, sujeito a algumas restrições. Existem duas classes bem conhecidas de tais problemas, denominadas como o Problema de Caixeiro Viajante (PCV), e o Problema do Carteiro Chinês (PCC). Com raras exceções, todos os problemas já formulados nessas duas classes são NP-completos. Portanto, para os problemas de maior porte existem apenas soluções aproximadas. Nessa Tese foi considerado o problema de determinar um circuito de custo mínimo que cobre um dado subconjunto de arcos, de arestas e de nós de um grafo misto, sujeito a algumas restrições nos vértices (restrições que proíbem conversões indesejáveis nos cruzamentos de malhas urbanas). Obviamente, o PCV, PCC e a maior parte de suas variações, como: o Problema do Carteiro Chinês Misto e o Problema do Carteiro Rural são casos particulares deste problema geral. A solução proposta é baseada numa transformação polinomial do grafo que possibilita a solução do problema resultante como um PCV padrão. Resultados computacionais confirmam a eficiência do método na obtenção de soluções próxima a ótimas para problemas razoavelmente grandes

Construction-based metaheuristics for personnel scheduling problems

This thesis investigates the idea of balancing different constraints in order to find optimal solutions to two personnel scheduling problems, within the framework of constructive metaheuristic approaches. The two problems considered are a nurse scheduling problem, for which finding feasible solutions is known to be difficult and for which the hard and soft constraints are in direct conflict, and a medical student scheduling problem for which there is little relevant literature this second problem also has conflicting hard and soft constraints, but presents further conflict between the different soft constraints. The methods used to solve these problems are focused on two constructive metaheuristics in particular: Greedy Randomised Adaptive Search Procedures (GRASP) and Ant Colony Optimisation (ACO) and for each approach several construction heuristics are introduced and compared. Using GRASP, a number of local search neighbourhoods are established for each problem, while for ACO the suitability of three trail definitions are compared. In order to further explore the balance which may obtained between the different constraints and objectives for the two problems, hybrid constructions are investigated, incorporating exact methods which take advantage of the underlying structures of each problem with regards to feasibility. For medical student scheduling, this exact method was developed into a new type of construction mechanism providing much improved results over a standard heuristic approach. Further enhancements investigated include the use of problem-specific feedback for nurse scheduling and the use of an intelligent memory procedure for the medical student scheduling problem. For the nurse scheduling problem, the final algorithm developed was able to rival the best in the literature so far and produce optimal solutions for all available datasets. For the medical student scheduling problem, optimal solutions are not known, but the results obtained are very promising and provide a good basis for further study of the problem.EThOS - Electronic Theses Online ServiceGBUnited Kingdo