Two Echelon Location-routing Problem With Simultaneous Pickup And Delivery

With the rapid growth of e-commerce,online' shopping has become the main consumption mode for most consumers,which has led to a large increase in parcel volume.How to quickly process,transport and distribute such a large amount of packages has become a huge challenge for urban logistics,which requires logistics companies to have an efficient logistics network.The two-echelon location-routing problem has become the core issue in the design of supply chains and distribution networks,especially in the design of new urban logistics distribution networks.Moreover,besides the delivery demand,the pickup demand is also increasing.It is necessary to design a logistics distribution network that can efficiently meet the both demands of customers.Therefore,this paper studies the two-echelon location-routing problem with simultaneous pickup and delivery(2E-LRPSPD).Aiming at the 2E-LRPSPD,this paper first analyzes the existing related literature.It is concluded that there is little research on this problem at present,and an efficient algorithm is lacking to solve this problem.Then,this paper scientifically characterizes the 2E-LRPSPD.A mixed integer formulation is proposed to obtain optimal locations of satellites and vehicle routes.The formulation considers the capacity constraints of the satellites,the capacity constraints of the vehicles in the two-echelon network,and the customer's simultaneous pickup and delivery demand.Because of the multiple capacity constraints in this problem,the solution is more complicated.Therefore,a multistart hybrid heuristic with path relinking is creatively proposed to efficiently solve the 2E-LRPSPD.In the hybrid heuristic,three greedy randomized constructive heuristics are first used to generate the initial solutions,and then a hybrid algorithm combining local search algorithm and variable neighborhood descent search is used to further optimize the initial solutions.The path relinking is added to the multistart hybrid heuristic as intensification and post-optimization steps.Finally,the experimental study is conducted to investigate the performance of the multistart hybrid heuristic with path relinking on international standard instances of two echelon location-routing problem and location-routing problem with simultaneous pickup and delivery.Results indicate that the multistart hybrid heuristic with path relinking can reduce the gap between the near optimal and global optimal solutions by 1%-2%.Then the multistart hybrid heuristic with path relinking is applied to a supermarket chain case in Turkey.The results show that the multistart hybrid heuristic with path relinking can be utilized to solve real-world problems.