Research On Vehicle Routing Problem Of Fresh E-commerce Distribution

China is the mayor country which produces and trades fresh agricultural products.Fresh agricultural products are the main food source.The traditional way of selling fresh agricultural products is the face-to-face trade between producers and buyers.Subsequently,the way of fresh agricultural products selling developed to the circulation mode of itinerant traders,wholesalers,fresh wholesale market and fresh supermarkets.Nowadays,with the development of information technology,the change of the people's consumption concept and the way of purchase,the development of fresh E-commerce is getting faster and faster.Fresh E-commerce has become one of the main channels for people to buy fresh agricultural products.Fresh agricultural products are easy to decay.Fresh agricultural products have short life cycle.So,it is difficult to guarantee the freshness of fresh agricultural products.Therefore,the characteristics of fresh E-commerce customers are multiple purchase frequency,small single purchase volume,random demand,geographically dispersed,requirements of service time window,freshness requirement of agricultural product,and so on.Fresh E-commerce companies require very high quality of logistics distribution,which makes the high logistics distribution costs.Logistics distribution has always been the bottleneck of fresh E-commerce companies.Logistics distribution has become the key link of “last kilometer” for the fresh E-commerce companies.The key to solve the logistics distribution problem of fresh E-commerce lies in scientific routes planning of distribution vehicles.That is to solve the vehicle routing problem(VRP)of fresh E-commerce companies.Different types of fresh E-commerce enterprises have different logistics distribution objectives,and have different vehicles.Customer coordinate distribution,purchase volume,time window and agricultural freshness requirements of different fresh E-commerce enterprises are different.Fresh E-commerce companies must carry out logistics distribution planning according to the enterprise objectives,the present logistics resources,customer needs and the traffic network,and so on.Fresh E-commerce companies should not only maintain the freshness of agricultural products,but also ensure the speed of distribution,and also minimize the total logistics cost.It is difficult to reasonable plan VRP of fresh E-commerce enterprises.So,it is urgent to lucubrate VRP of fresh E-commerceenterprises.This paper studies the logistics distribution problems of fresh E-commerce enterprises from different perspectives.This paper analyzes the logistics distribution demand of different products of fresh E-commerce,and describes the different distribution scenarios of fresh E-commerce enterprises.The research details are described as follows:(1)The vehicle routing problem with time windows(VRPTW)of fresh E-commerce with freshness restriction is studied.The freshness measure function of fresh agricultural products is introduced by considering that the freshness of fresh agricultural products decreases with time under normal temperature condition.Considering that the customers of fresh E-commerce companies are mainly distributed in the city and the urban traffic network has time-varying characteristics,the calculation method of vehicle travel time under the time-varying network is introduced.Then,the comprehensive consideration is given to factors such as vehicles depart from distribution center at different times,vehicle capacity,customer demands,time windows,service time and freshness of agricultural product,the VRPTW mathematical model of fresh E-commerce with minimum freshness is constructed in order to minimize the total distribution costs.According to the characteristics of the model,an immune ant colony algorithm is designed to solve the problem.Finally,multi-type cases are used to prove the rationality and effectiveness of the proposed method.The research results will provide decision-making reference for fresh E-commerce companies to distribute the agricultural products with strong freshness anti-decay property under normal temperature condition.(2)By considering both distribution economic cost and environmental cost of fresh E-commerce,the time-dependent vehicle routing problem(TDVRP)of cold chain distribution is studied.At first,the time-varying characteristics of urban traffic network are analyzed,and the calculation method of road travel time based on time-section division is designed,and the calculation function of vehicle carbon emissions is introduced.By comprehensive considering the factors such as vehicles depart from distribution center at different times,vehicle capacity,customer demands,time windows and service time,the sum of the manpower cost and the fixed use cost of the vehicle is used as the distribution economic cost,and the sum of the fuel consumption cost and the carbon emission cost is used as the environmental cost.In order to minimize the sum of distribution economic cost and environmental cost,the TDVRPmathematical model of cold chain distribution of fresh E-commerce is constructed.According to the characteristics of the model,an improved ant colony algorithm is designed to solve the TDVRP.Finally,multi-type cases are used to prove the rationality and validity of the proposed approaches.The purpose of this paper is to provide a decision-making reference for fresh E-commerce companies to adopt cold chain mode to distribution agricultural products with higher added value and with weak freshness anti-decay property.(3)The low-carbon time-dependent vehicle routing problem(LCTDVRP)with traffic congestion avoidance method of fresh E-commerce is studied.Considering that traffic congestion has become a common phenomenon in large and medium-sized cities,the time-varying characteristics of urban traffic network are analyzed,and the calculation method of road travel time under vehicle non-stop strategy is designed.Then,the method of calculating the total vehicle usage time under the vehicle congestion stopping strategy is designed.The calculation function of vehicle carbon emissions is employed.By comprehensive considering vehicles depart from distribution center at different times,vehicle capacity,customer needs,time windows,service time,vehicle carbon emissions and other factors,the LCTDVRP mathematical model of fresh E-commerce is constructed with the minimum carbon of total vehicles.The traffic congestion avoidance method based on the congestion index is designed.According to the characteristics of the LCTDVRP model and traffic congestion avoidance method,a hybrid ant colony algorithm for solving LCTDVRP is designed.Numerical examples are used for simulation experiment in order to prove the rationality and validity of the proposed approaches.The proposed methods will provide a decision-making reference for the implementation of low-carbon logistics of fresh E-commerce enterprises.(4)The open multi-depot vehicle routing problem(OMDVRP)with joint distribution strategy of fresh E-commerce is studied.By considering that the large-scale fresh E-commerce enterprise has multiple logistic centers,a multi-depot processing method for sharing total logistics resources is designed.The freshness measurement function of agricultural products is introduced.By comprehensive considering that vehicles depart from depot at different times,vehicle capacity,customer demands,service windows,freshness limitation of fresh agricultural product,and other factors,the OMDVRP mathematical model with joint distribution strategy for fresh E-commerce is constructed in order to minimize the total distribution costs.A hybridheuristic algorithm is designed according to the characteristics of the model.Finally,multi-type examples are used to prove the rationality and validity of the proposed approaches.It is hoped that the proposed methods of joint distribution can be used for reference for fresh E-commerce enterprises with multiple distribution centers.The research results will further enrich the theory and methods of management science and logistics management.This paper will provide reference for peer research,provide reference for fresh E-commerce enterprises in logistics distribution decision-making,and provide relevant policy suggestions for relevant government departments.