Research On Optimization Of Low Carbon Cold Chain Distribution Route Of Time-Varying Road Network Based On Customer Satisfaction

With the continuous growth of Chinese residents’ per capita disposable income,fresh agricultural products,egg dairy products,low temperature fresh milk and other raw products in People’s Daily diet is also growing,which has created a huge market for cold chain logistics industry.Raw products are easy to deteriorate,and refrigeration equipment is required to strictly control the storage temperature in the transportation process,which will consume a lot of fuel,generate additional carbon dioxide emissions,make the economic cost of cold chain logistics too high,but also cause more negative impacts on the environment and urban traffic.Customer satisfaction affects the operating performance of logistics enterprises to a large extent,and thus determines the viability of logistics enterprises.Therefore,it is equally important to improve customer satisfaction with cold chain logistics distribution services.Based on this,this paper proposes a time-varying green vehicle routing problem that satisfies customers.This problem takes urban cold chain logistics as the main research subject,aiming at reducing economic cost of transportation and carbon emissions,improving customer satisfaction through reasonable planning of distribution routes.The main research of this paper is as follows:(1)Construct a multi-objective optimization model.In this paper,the time-varying characteristics of the actual road network,customer satisfaction with the distribution service and low-carbon environmental protection requirements were comprehensively considered.Under the constraints of vehicle load,customer time window and other conditions,a multi-objective optimization model was constructed with the aim of minimizing the total economic cost and maximizing customer satisfaction.The total economic cost includes fixed cost,fuel cost,cooling cost and carbon emission cost.Customer satisfaction comprehensively measures the accuracy of delivery time and the freshness of delivery goods.Considering the continuous change of travel speed with time,this paper adopts the calculus idea to calculate the fuel consumption.(2)The improved NSGA-II algorithm is designed to solve the multi-objective optimization model.The improved NSGA-II algorithm mainly consists of population initialization,fast non-dominated sorting,adaptive genetic manipulation and large-scale domain search operation.The adaptive crossover probability is used to make it adaptive.The damage operator and repair operator are used to conduct large-scale neighborhood search,avoids the population falling into the local optimal solution.(3)Analysis of time-varying road network path travel time.In this paper,the time-varying road network is represented based on the continuous function of travel speed time dependence.Firstly,the time-varying characteristics of the selected region are analyzed,then the travel speed time dependence continuous function is fitted,and finally the travel time is calculated.(4)Based on the actual road network,the simulation experiment is constructed to simulate the real distribution situation.In the actual road network,there are few straight roads that directly connect the two nodes,and the distance between the two nodes is difficult to calculate.In this paper,the optimal path recommended by the 100 map is used as the driving path,and the distance measurement is realized by using the ranging tool.Then the sensitivity analysis and comparative analysis of the results were carried out.The results show that the economic cost and customer satisfaction of the distribution scheme are different with different departure time of vehicles,and the effect of energy saving and emission reduction are also different,which makes the distribution scheme of refrigerated trucks more flexible.In addition,the satisfaction weight of the delivery time and the satisfaction weight of the freshness of goods are different,and the results are not the same.Compared with the results obtained under static road network,the economic cost,unit customer satisfaction cost and emissions are reduced by 4.80%,8.97% and 6.98% on average under time-varying road network,and customer satisfaction is increased by 4.54% on average.The importance of considering a time-varying road network is confirmed by the fact that it can effectively improve customer satisfaction and reduce emissions during transportation.