multiple allocation

In this research, a modular hub location problem has been investigated where the objective is to reduce the transportation costs in the hub network. The proposed model determines the location of hubs, allocation of the non-hub nodes to the hubs, and the optimal vehicle traffic, i.e., the number of flights or the number of trucks traveling in the network, considering the appropriate capacity for each vehicle. Also, decisions regarding the percentage of the traffic volume sent via multiple network routes are made by the presented model.

The mathematical model, including the objective function and constraints, is constructed and solved by GAMS software. The effect of different parameters on the results is investigated. Due to long solution times for the MIP model, a heuristic solution method based on LP relaxation of the integer variables is developed for the proposed problem, which is able to obtain near-optimal solutions in less time.

The developed mathematical model is implemented on the air passenger transportation data for the airports of the United States of America, which is known as the CAB data set. The results give the optimal number of hubs, as well as the optimal number of transportation units on each arc of the network, which depend on the capacity of the means of transportation.

Originality/Value:

 In this research, a mixed integer programming model is developed for the multiple allocation modular hub location problem. Numerical experiments are conducted with the use of GAMS software and the results are discussed.

Hub location problems have important role in transportation networks and telecommunication systems. These problems have received much attention in the recent decades. In p-hub median problem، hub facilities are located in a network and non-hub nodes are allocated to hub nodes such that the total routing cost is minimized. In this paper، the r-Allocation p-Hub median problem has been studied. In this problem، each node can be allocated to at most r hubs. The purpose of this paper is to study and design of an exact solution approach based on benders decomposition to tackle the proposed problem. Based on problem structure، we proposed some strategies to accelerate the convergence of benders decomposition algorithm. The computational results of the proposed exact algorithm are presented using the Turkish network and USA423 data sets. Computational experiments confirm the effectiveness of the proposed method

This paper proposes a new mathematical model for designing and planning postal parcels carriage and postal networks. The objective of postal network designing is to determine the location, size and connection between the postal stations in a city, province or country. In this paper, a kind of multiple locations-allocations hub problem with limited capacity in collecting, distributing and broadcasting by the hub in a network with the desired interval structure is studied. A multi-commodity network transportation with demand, transportation cost, possible capacity and three kind of hubs is considered in a long-term time horizon. Since the mathematical modeling is a non-linear mixed integer programming problem, the aim is to decide on hub kinds and on the points that should be assigned to the established hubs. Numerical experiments demonstrate the significance and applicability of the proposed model for actual decision-making problems.