Research On Location-routing Problem Of Emergency Logistics System Under Uncertain Conditions

The loss of national economic property and the number of casualties caused by natural disasters and public security events are extremely striking.Because natural disasters are sudden,destructive and unpredictable,scientific and reasonable rescue measures must be taken to reduce the losses caused by natural disasters.However,in the process of carrying out rescue work,it is faced with the problem of low timeliness and economy of emergency materials distribution.Therefore,to improve the timeliness and economy of emergency materials distribution and reduce the loss of people’s life and property caused by various disasters,scientific and effective logistics system planning is needed.The two most basic and important elements of studying the operation of the emergency logistics system are the location of the emergency distribution center and the planning of the rescue route.Therefore,the research on the location route optimization of the emergency logistics system is necessary to improve the scientific of the emergency rescue activities,strive for the precious rescue time and maximize the efficiency of the rescue resources.In order to improve the timeliness and economy of emergency material distribution,this thesis takes the emergency logistics system in the early stage of natural disasters as the research object,optimizes the location path problem in the emergency logistics system,and provides a certain reference value for the emergency material distribution problem in the actual work.The work of this thesis includes:This thesis studies the logistics planning in the preparation and response stages of natural disaster life cycle.In the pre disaster preparation stage,it mainly determines the quantity,location and emergency material inventory strategy of the distribution center;in the post disaster response stage,it formulates the disaster area material distribution plan and plans the vehicle path.Based on the extraction of many elements of the conceptual model of location path problem in emergency logistics system,the uncertain factors of scenario differences caused by different disasters are used to transform the objective condition constraints into model constraints.The optimization model of location path problem under the uncertain conditions is proposed with the objective of the shortest total time and the minimum total cost.Among them,the upper level of the model takes the minimum total cost of the rescue system as the objective function,and the lower level takes the optimal response time under the worst disaster scenario as the objective function;the disaster scenario diversity in the model is quantitatively described by the difference of material demand under each scenario,and the material transfer mechanism of the distribution center of the same level is included in the model as the innovation of the thesis,so as to find the economic satisfaction Efficient and time efficient disaster relief programs.After that,the improved model is applied to the calculation of small-scale cases,so that the model in this thesis is compared with the traditional location,path independent planning model and stripping and transferring mechanism model.Finally,the random planning based on the probability of disaster occurrence scenario is used as the application extension of the model in this thesis,which proves that the model can provide better reference for the rescue decision makers.This thesis uses genetic algorithm and MATLAB programming to solve the above model.The penalty function is used to deal with some constraints in the model,and the weighted method is used to integrate the two objectives into a single objective form.Finally,the numerical examples show that the established model and its variants can achieve satisfactory optimization results in a short time,which shows the availability of the model and algorithm.