The Research Of P-median Location Problem With R-interdiction

Vulnerability to sudden service disruption due to deliberate sabotage and terrorist attacks is one of the major threats for network system. Thus, facility location strategy in network should concern the operational cost in peacetime and emergency. We have cast this problem as a bi-level binary programming model ,we use hybrid genetic algorithm based and Tabu search ,we also applied it to European 150 data set, we compare the new mode with the traditional mode ,at last we discuss the sensitivity of the results.The article introduce the source of the problem firstly .Then we list several algorithms of the P-median problem. This article focuses on how to locate P facilities so as to minimize expected cost including the regular operational cost as well as the emergent operational cost of a worst-case attack with the interdiction of R facilities. We have cast this problem as a bi-level binary programming model where the top level problem involves the decisions about where to locate facilities and the lower level problem entails the interdictor response on which facilities to attack. We solve the bi-level problem through hybrid genetic algorithm based on Tabu search, which is proven to be the best heuristic for the lower level model by computational tests. Results of this problem and traditional P-median location problem applied to European 150 data set are presented. Several solutions derived from these models are presented in greater detail and demonstrate the degree to which the loss of R facilities affects network system efficiencies with different location strategy decided by these models. Then we discuss the sensitivity of the results to changes in key parameters including the weight of regular condition, the number of facilities and the number of facilities interdicted. Finally, recommendations for future research are also made.