Research On Emergency Logistics Site Selection-path Optimization Problem Considering Demand Grading

In recent years,all over the world are facing the impact of various emergencies such as natural disasters,serious accidents,major epidemics,terrorist attacks and local wars,which have great impact on people’s lives and economic and social stability.However,in China,the management system of emergencies started late,the system is not perfect,the relevant theory is not perfect,and there are gaps in the relevant research.The disaster relief process of emergency is a complex and dynamic system engineering,how to effectively allocate the materials,determine the location of the warehouse,and transport the materials to the affected point is the most important point.And the severity of the disaster varies from one disaster site to another after an emergency,not only in the amount of supplies needed,but also in the urgency of the needs of each disaster site.On the basis of combing and analyzing the existing studies,the disaster point demand grading is considered and the problem of emergency logistics warehouse site selection and vehicle path optimization is solved.The index factors affecting the demand grade of the disaster site are analyzed,a disaster site demand grading evaluation index system is established,and the fuzzy-type index values are defuzzified.The CRITIC-TOPSIS comprehensive evaluation model is constructed to determine the comprehensive evaluation index of each disaster site.Finally,the clustering spectrum map was generated by systematic clustering in SPSS cluster analysis,and the cluster spectrum map was analyzed to classify all disaster sites into 5 demand levels.In the construction of emergency logistics site-path optimization model,the base model was constructed with the goal of shortest total time and lowest total cost required for emergency rescue;by adding the objective function of comprehensive ranking index of demand level of affected points to give priority to the affected points with high demand level for transportation,at this time,a comprehensive single objective function F was added to make the three objective functions constrain each other by assigning weights,so as to meet the optimal overall effect of the model.The improved model is obtained.The NSGA-II algorithm of the multi-objective heuristic algorithm is chosen to solve the model,which has good robustness and stability,so as to obtain a better feasible solution.Taking the emergency logistics site-path scheme selection under the Covid-19 in July 2022 in Nanchang,Jiangxi Province as a practical calculation example,the optimal site-path optimization scheme of the base model and the improved model is obtained by pre-processing the data according to the realistic situation and adjusting the relevant parameters in the operation process.By comparing the two solutions and conducting sensitivity analysis on the weight coefficients of the objective function,after considering the demand situation of the affected sites,the total time and total cost increase slightly,the comprehensive ranking index of the demand level of the affected sites decreases significantly,and the transmission risk and life safety risk faced by each affected site decreases significantly,and the optimal solution of the improved model is more reasonable for the actual situation and minimizes the damage caused by the disaster.The optimal solution of the improved model is more reasonable for the actual situation,so as to minimize the loss caused by the disaster.