The design and management of a multi-stage production/distribution system is one of the most critical problem in logistics and in facility management. This manuscript deals with the so called facility locationallocation problem, i.e. with the simultaneous decisions regarding the design, management, and control of a distribution network. In particular the logistic problem object of this study de...

In this paper, a model is presented to locate ambulances, considering backup facility (to increase reliability) and the restriction of ambulance capacity. This model is designed for emergencies. In this model the covered demand for each demand point depends on the number of coverage times and the amount of demand. The demand amount and ambulance coverage radius are considered...

Hub location problems are strategic network planning problems. They formalise the challenge of mutually exchanging shipments between a large set of depots. The aim is to choose a set of hubs (out of a given set of possible hubs) and connect every depot to a hub so that the total transport costs for exchanging shipments between the depots are minimised. In classical hub location problems, the un...

Abstract Many of air cargo companies adapt the hub-and-spokes system where economies of scale exist in the transportation cost. In this paper, we formulate economies of scale using nonlinear cost function of distances and demands, and analyze how the change of the transportation cost affects single hub location of air cargo using the generalized Weber problem on the regular demand points of one...

Abstract One of the basic assumptions in hub covering problems is considering the covering radius as an exogenous parameter which cannot be controlled by the decision maker. Practically and in many real world cases with a negligible increase in costs, to increase the covering radii, it is possible to save the costs of establishing additional hub nodes. Change in problem parameters during the pl...

This paper considers the discrete two-hub location problem. We need to choose two hubs from a set of nodes. The remaining nodes are to be connected to one of the two hubs which act as switching points for intemodal flows. A configuration which minimizes the total flow cost needs to be found. We show that the problem can be solved in polynomial dme when the hub locations are fixed. Since there a...

Globalization of world economy has led to a rapid growth of container transportation as well as container ports. In China, Shanghai and Ningbo ports have experienced an explosive growth rate based on their strong economic hinterlands. The purpose of this paper is to adopt regional economic theory and methods to quantitatively analyze the spatial structure of the ports cluster and the competitiv...

The Single Allocation Ordered Median Hub Location problem is a recent hub model introduced in [36] that provides a unifying analysis of a wide class of hub location models. In this paper, we deal with the capacitated version of this problem, presenting two formulations as well as some preprocessing phases for fixing variables. In addition, a strengthening of one of these formulations is also st...

In this paper, we present an effective solution using the genetic algorithm for the uncapacitated single allocation hub location problem (USAHLP). This solution was published before, but today it still gives the really effective results, although there are many studies have been done after it. We also make an application using this method and present the performance results of this method.