Research On Two-Stage Distribution Optimization Of Emergency Supplies Considering The Time Difference Of Transfer Station Arrival

After a sudden disaster occurs,emergency relief supplies need to be transported by large vehicles from multiple distribution centers to multiple transfer stations,and then replaced by small vehicles from the transfer stations to the demand points for two-level distribution after reaching the transfer stations.In the distribution of emergency supplies,each demand point wants to meet all its demands at once within the specified time as much as possible;otherwise,it will incur delay penalty cost and unsatisfied penalty cost.In this paper,we consider that there is a delivery time difference from different distribution centers to the same transfer station for emergency supplies,and study the two-level distribution path selection problem that minimizes the total distribution cost(delay penalty cost+unmet penalty cost+vehicle use cost+transportation cost)for all demand points in the case of sufficient emergency supplies and minimizes the maximum distribution cost(delay penalty cost+unmet penalty cost+vehicle use cost+transportation cost)for a single demand point in the case of shortage of emergency supplies,and build a model and solve it.The main work and innovative results of the paper are as follows.The two-stage distribution model and solution for minimizing the total cost of distribution at all demand points under the situation of delivery time difference at transfer stations and sufficient emergency supplies.For the situation that there is a delivery time difference at the transfer station and sufficient emergency supplies,the objective is to minimize the total cost of distribution at all demand points,establish a two-level distribution path selection model considering the delivery time difference at the transfer station and sufficient emergency supplies,design an exact algorithmTR~*with time complexity O(n 4)to solve the model,and make the decision that the emergency supplies arrive at the transfer station and are transported to the demand point.The starting time and number of vehicles used to transport emergency supplies to the demand point after arriving at the transfer station,and the two-level distribution volume and distribution path selection scheme are given.Finally,we analyze the two-level distribution of emergency supplies in Shanghai with the example of COVID-19 pandemic to verify the effectiveness of the model and algorithm.The two-stage distribution model and solution for considering the delivery time difference at the transfer station and minimizing the maximum distribution cost at a single demand point under the shortage of emergency supplies.In the case of delivery time difference at the transfer station and shortage of emergency supplies,the two-stage distribution path selection model considering the delivery time difference at the transfer station and shortage of emergency supplies is established with the objective of minimizing the maximum distribution cost at a single demand point,and an exact algorithm with time complexity O(n 3)is designedSR~*solved to make the decision that the emergency supplies arrive at the transfer station and are transported to the demand point.The starting time and the number of vehicles used to transport emergency supplies to the demand point after arriving at the transfer station,and the two-level distribution volume and distribution path selection scheme are given.Finally,we analyze the two-level distribution of emergency supplies in Shanghai with the example of the COVID-19 pandemic to verify the effectiveness of the model and algorithm.