Two Level Distribution Route Selection Of Emergency Materials Considering Demand Importance

After the occurrence of sudden disasters,large vehicles are dispatched from the emergency supplies storage center to transport emergency supplies to material distribution points,where small vehicles are then dispatched to deliver the supplies to the material demand points.Considering the shortage of emergency supplies and the different importance levels of the same type of supplies at different demand points,we define the unit demand importance of each demand point for the same type of material.Our objectives are to maximize the total demand importance∑(unit demand importance of each demand point for the same type of material*actual supply quantity of the material at each demand point)and minimize the total transportation cost,or to minimize the difference between the maximum demand importance generated by satisfying all demands at a single demand point and the actual demand importance produced by the delivered materials,while minimizing the total transportation cost.We aim to determine the two-level delivery vehicle routes from the distribution center to the distribution points and then to the demand points,as well as the emergency supply volumes.This paper proposes two objectives and establishes a mathematical model,which is solved using an algorithm based on ant colony optimization or simulated annealing.Finally,numerical experiments are conducted to evaluate the performance of the proposed algorithm and to provide insights into the practical implementation of the results.Consider the selection of two-level distribution path for emergency supplies taking into account the importance of total demand and total transportation cost.In the case of insufficient emergency supplies and different demand importance for the same type of emergency supplies at different demand points,a two-level distribution path selection model for insufficient emergency supplies is established with the dual objectives of maximizing the total demand importanceΣ(the unit demand importance of each demand point for the same type of supplies multiplied by the actual distribution quantity of supplies for that point)and minimizing the total transportation cost.The model comprehensively considers the minimum transportation cost from distribution points to each demand point and the maximum demand importance of that point,and is solved using an approximate algorithm A with a complexity of O(ln~2).The distribution quantity of emergency supplies and the two-level distribution path of emergency supply vehicles for each distribution point and demand point are decided,and the approximation ratio of approximate algorithm A is analyzed.Finally,taking the earthquake in Menyuan County,Qinghai,as the main case study,the validity of the established model and method is examined.Consider the selection of two-level distribution path for emergency supplies taking into account the demand importance of a single demand point and the total transportation cost.In the case of insufficient emergency supplies and different demand importance for the same type of emergency supplies at different demand points,a two-level distribution path selection model for insufficient emergency supplies is constructed with the dual objectives of minimizing the difference between the maximum demand importance generated by the delivery of supplies to a single demand point and the demand importance generated by the actual delivered supplies,and minimizing the total transportation cost.The model is analyzed in two specific cases based on whether the demand importance of a demand point is greater than or equal to the difference between the maximum demand importance generated by the delivery of supplies to a single demand point and the demand importance generated by the actual delivered supplies.An approximate algorithm GA with a complexity ofO(ln~2)is designed to solve the model,deciding the distribution quantity of emergency supplies for each distribution point and demand point,and the two-level distribution path of emergency supply vehicles.The approximation ratio of approximate algorithm GA is analyzed.Finally,using the earthquake in Menyuan County,Qinghai,as an example to examine the validity of the established model and algorithm.