Sistemas eixo-raio de múltipla atribuição: modelos e algoritmos

Abstract

In telecommunication and transportation systems, the multiple allocation hub location problem arises when we must flow commodities or information between several origin-destination pairs. Instead of establishing a direct node to node connection from an origin to its destination, the flows are concentrated with others at facilities called hubs. These flows are transported on links established between hubs, being then splitted and delivered to its final destination. Systems with this sort of topology are named hub-and-spoke systems or hub-and-spoke networks. They are designed to exploit the scale economies attainable through theshared use of high capacity links between hubs. Therefore, the problem is to find the least expensive hub-and-spoke network, selecting hubs and assigning traffic to them, given the demands between each origin-destination pair and the respective transportation costs. In the present work, we study threedifferent versions of the problem: the classical, the flow dependent scale economies and the congestioned. Efficient Benders decomposition algorithms have been deployed to tackle the problems. We have been able to solve some large instances, considered out of reach' of other exact methods in reasonable time.