Research On Multi-Objective Emergency Pharmaceutical Cold Chain Distribution Path With Fuzzy Constraints

In recent years,the emergency medical cold chain has attracted the attention of the government and many scholars.In 2021,the National Development and Reform Commission issued the "14th Five-Year Plan" Cold Chain Logistics Development Plan,proposing to "speed up and improve the construction of cold chain logistics facilities for pharmaceutical products,build a unified emergency linkage service scheduling mechanism,and improve the level of cold chain emergency support for pharmaceutical products".In 2022,the Report of the Second 10 th National Congress of the Communist Party of China also pointed out the need to "strengthen the prevention and treatment system and emergency response capacity building for major epidemics".In 2023,the Party’s Report on the Work of the Government also proposed to "improve the system of prevention,control and treatment of major epidemics and emergency supplies","improve the capacity of medical and health services,and deepen the reform of the medical and health systems".In addition,many scholars have studied the distribution route optimization of emergency system and cold chain system under uncertain factors,but most of the studies focused on the time window,and few literatures studied fuzzy risk and cost in emergency situations.Therefore,this paper aimed at the multi-objective distribution route problem with fuzzy time window in emergency medical cold chain.A multiobjective distribution route optimization model considering route fuzzy risk and cold chain cost was proposed.NSGA-Ⅱ algorithm was improved to optimize the distribution route with the goal of shortest transportation time,minimum risk and lowest cost.Firstly,the fuzzy risk on the path is considered under the fuzzy time window constraint problem.Taking the shortest transportation time and the lowest risk as the optimization objectives,a dual objective path optimization model with fuzzy constraints is constructed.NSGA-Ⅱ algorithm is improved by using a more concise integer coding method and PMX crossover mutation operator which can improve the quality of Pareto solution set.Finally,the validity of the model and algorithm is verified.The results show that the satisfactory solution can be obtained by improving the algorithm.The result is between the optimal solution of each result under single objective,which is an effective improved algorithm.This algorithm can provide route optimization scheme for transportation companies under emergency events and provide reference for relevant government departments to deal with emergency medicine distribution.Secondly,on the basis of the dual-objective model,the costs in the cold chain distribution process were systematically considered.Taking the shortest transportation time,the lowest risk and the lowest cost as the optimization objectives,the distribution vehicle routing optimization model was established and solved.Through the improved NSGA-Ⅱ algorithm,The optimal distribution route is found under the balance of three contradictory objectives: transportation time,transportation risk and transportation cost,and the effectiveness of the model and algorithm is verified.The results show that the multi-objective solution can be obtained by improving the algorithm.In addition,the study found that there is a positive correlation between transportation cost and transportation time,while there is little correlation between transportation risk and transportation cost.The relevant conclusions can provide the basis for government departments to make transportation plans and decisions when the budget is limited or transportation companies pursue cost optimization.