a new multi-mode and multi-product hub covering problem‎: ‎a priority m/m/c queue ‎approach

one main group of a transportation network is a discrete hub covering problem that seeks to minimize the total transportation cost. this paper presents a multi-product and multi-mode hub covering model, in which the transportation time depends on travelling mode between each pair of hubs. indeed, the nature of products is considered different and hub capacity constraint is also applied. due to the transport volume and related traffic, a new priority m/m/c queuing system is considered, in which products with high priority are selected for service ahead of those with low priority. the objectives of this model minimize the total transportation cost and total time. besides, because of the computational complexity, a multi-objective parallel simulated annealing (mopsa) algorithm is proposed and some computational experiments are provided to illustrate the efficiency of the presented model and proposed mopsa algorithm. the performance of this algorithm is compared with two well-known multi-objective evolutionary algorithms, namely non-dominated sorting genetic algorithm (nsga-ii) and pareto archive evolution strategy (paes)‎.‎