Resource constrained routing and scheduling: Review and research prospects

In the service industry, it is crucial to efficiently allocate scarce resources to perform tasks and meet particular service requirements. What considerably complicates matters is when these resources, for example skilled technicians, nurses, and home carers have to visit different customer locations. This paper provides a comprehensive survey on resource constrained routing and scheduling that unveils the problem characteristics with respect to resource qualifications, service requirements and problem objectives. It also identifies the most effective exact and heuristic algorithms for this class of problems. The paper closes with several research prospects

Um problema de VRP: alocação de técnicos em uma empresa de telecomunicações, levando em conta tempos estocásticos e janelas de tempo.

TCC(graduação) - Universidade Federal de Santa Catarina. Centro Tecnológico. Engenharia de ProduçãoO presente trabalho é um estudo de caso sobre o processo de alocação de técnicos a tarefas em uma empresa de telecomunicações. Criou-se um modelo matemático que representa o processo em questão para um dado período, enquadrando a situação apresentada como pertencendo a um caso de problema de roteirização de veículos com janelas de tempo e tempos estocásticos. Implementou-se tal modelo computacionalmente, com o intuito de realizar uma alocação eficiente das tarefas, de modo a garantir o cumprimento do prazo das mesmas, ao mesmo tempo em que busca-se reduzir os custos operacionais e balancear as horas dedicas à empresa entre os técnicos. Com a aplicação do modelo proposto e a análise dos resutaldos obtidos, foi possível recomendar mudanças no sentido de melhorar o desempenho operacional da empresa. Desta forma foi observado a possibilidade de reduzir o número de técnicos, avaliar o impacto de programas de treinamento, além da realização de um melhor controle em como as tarefas são realizadas.The presente work is a case study about the scheduling process of technicians to service bookings of a telecommunications company. A mathematical model was created in order to represent the referred process, framing the situation as belonging to the family of VRPTWs (Vehicle Routing Problem with Time Windows) with stochastic times. Such a model was implemented via computer with the purpose of building an efficient schedule, guaranteeing that tasks are completed on time, as well as pursuing lower operational costs and a fairer distribution of work hours among technicians. By applying the proposed model and analyzing the subsequent results, it was possible to make some recommendations in order to enhance the company’s performance. So it was observed the possibility of reducing the number of technicians, evaluate the impact of training programs and the realization of a better control of the way in which tasks are executed

Metapopulation Modelling and Spatial Analysis for HEG Technology in the Control of Malaria

The success of any vector control strategy can be enhanced by onsite analysis and investigation. Combatting malaria, a global disease carried by the vector Anopheles gambiae, has led to the development of novel genetic technologies such as the use of HEG; homing endonuclease genes. This thesis explored the age and stage elements of the vector, building upon current biological understanding and using fitting algorithms with metapopulation matrices to create cohort orientated survival and transition. The environmental forces were analysed alongside this with emphasis on sub-model creation and tool design, employing an array of methods from RBF to satellite classification to couple the local environment and vector. When added, the four potential genetic strategies all demonstrated the ability to suppress a wild type population and even eradicate it, although reinvasion and hotspot population phenomena were reoccurring observations. The movement of the vector was an important factor in control efficiency, which was investigated as a series of different assumptions using wind driven movement and host attraction. Lastly, practical factors such as monitoring and resource distribution within a control project were assessed, which required routing solutions and landscape trapping assessments. This was explored within a framework of Mark-Release-Recapture experiment design that could provide critical information for efficient HEG release strategies.Open Acces

Optimisation de tournées de service en temps réel

RÉSUMÉ : Les tournées de service concernent l'organisation de déplacement de personnels vers des clients afin d'effectuer différentes activités techniques ou commerciales. Ces tournées peuvent devoir répondre à des objectifs et faire face à des contraintes nombreuses et complexes. Lors de la planification et de l'exécution de tournées de service mono-période, les entreprises sont confrontées aux aléas des temps de service et de parcours. C'est pourquoi, dans cette thèse, nous nous intéressons à une variante du problème de tournées de service, dans laquelle les temps de parcours et de service sont stochastiques. Il s'agit du problème de tournées de service multi-dépôt, incluant fenêtres de temps, temps de service et de parcours stochastiques avec priorité entre les clients (distinction clients obligatoires / clients optionnels). Afin de résoudre cette problématique, nous proposons trois méthodes différentes. Dans la première méthode, nous construisons d'abord des routes contenant uniquement des clients obligatoires puis nous procédons à l'insertion des clients optionnels. La deuxième méthode est une méthode approchée basée sur la génération de colonnes consistant à générer un ensemble de routes de bonne qualité pour chaque véhicule puis à en sélectionner une par véhicule. La dernière méthode est un algorithme de branch and price basé sur la deuxième méthode. Le sous-problème consiste à générer des routes réalisables pour un véhicule donné, tandis que le problème maître permet de sélectionner des routes en s'assurant que la priorité des clients est respectée. Après chacune de ces méthodes, afin d'évaluer la qualité de ces solutions face aux aléas, nous utilisons un algorithme de programmation dynamique et procédons à un ensemble de simulations du déroulement des tournées en temps réel. Nous avons testé ces méthodes sur des problèmes dont les données sont issues du milieu industriel.Mots-clés : Tournées de véhicules, multi-dépôt, fenêtres de temps, temps de service stochastiques, temps de parcours stochastiques, priorité entre les clients.----------ABSTRACT : The field service routing problem consists in assigning the visits of technicians to clients in order to satisfy their requests for service activities such as maintenance. When planning service routes, companies have to face hazardous travel and service times. Therefore, in this thesis, we deal with a variant of the single-period field service routing problem in which travel and service times are stochastic. It is the field service routing problem with multiple depots, time windows, stochastic travel and service times and priority within customers (distinguishing mandatory and optional customers). To solve this problem, we propose three different methods. In the first one, we first build routes containing only mandatory customers and then, we insert optional customers in these routes. The second one is a heuristic method based on column generation consisting in generating a set of valuable routes for each vehicle and then in selecting one route per vehicle. The last method is a branch and price algorithm, based on the second method, in which the subproblem consists in finding feasible routes for a given vehicle, whereas the master problem consists in selecting routes while ensuring that customer's priority is respected. After each of these methods, in order to evaluate the quality of these solutions regarding stochasticity, we use a dynamic programming algorithm and we proceed to a set of simulations of the real-time execution of the service activities over the period. All our experimentations have been made on problems coming from realistic data. Keywords : Vehicle routing, multi-depot, time windows, stochastic service times, stochastic travel times, priority within customers

On the partitioning of dynamic workforce scheduling problems

This problem is based on the British Telecom workforce scheduling problem, in which technicians (with different skills) are assigned to tasks (which require different skills) which arrive (partially) dynamically during the day. In order to manage their workforce, British Telecom divides the different regions into several areas. At the beginning of each day all the technicians in a region are assigned to one of these areas. During the day, each technician is limited to tasks within the assigned area. This effectively decomposes a large dynamic scheduling problem into smaller problems. On one hand, it makes the problem more manageable. On the other hand, it gives rise to, potentially, a mismatch between technicians and tasks within an area. Furthermore, it prevents technicians from being assigned a job which is just outside their area but happens to be close to where they are currently working. This paper studies the effect of the number of partitions on the expected objective (number of completed tasks) that a rule-based system (responsible for the dynamic assignment and reassignment of tasks to resources following dynamic events) can reach. © 2009 Springer Science+Business Media, LLC