Research On Cold Chain Logistics Distribution Path Planning Of Fresh Agricultural Products Under Time-Varying Road Network

China is a big country in the production and consumption of fresh agricultural products.With the development of cold chain logistics industry,the role of cold chain logistics in the transportation of fresh agricultural products is increasing.Compared with ordinary logistics,cold chain logistics has the characteristics of strong timeliness and large resource consumption.At present,the cold chain logistics distribution of fresh agricultural products is mainly based on the demand of high frequency and small batch,and the problems of low transportation efficiency and high logistics cost restrict the development of this industry.Therefore,this paper takes the cold chain logistics path planning of fresh agricultural products as the research object,analyzes the influencing factors of the distribution process in many aspects under the condition of time-varying road network,and builds a mathematical model with the lowest total cost as the optimization goal,which has positive significance for rational planning of cold chain logistics distribution path and optimization of logistics network.First of all,this paper analyzes in detail the development status and distribution mode of cold chain logistics of fresh agricultural products in China,and introduces the theories related to vehicle path optimization and time-varying road network.Secondly,the timevarying road network is introduced,and the driving speed of distribution vehicles is constantly changing under the influence of morning and evening peak in the city.This paper studies the influence of vehicle speed differences in different time periods on delivery time.Considering the time constraint of cold chain logistics distribution,this paper combines soft and hard time Windows and defines the penalty cost function of mixed time Windows.Thirdly,this paper takes the vehicle load and the user’s time window as constraint conditions,and constructs a cold chain logistics distribution model of fresh agricultural products aiming at minimizing the total distribution cost,which includes fixed cost,cargo damage cost,refrigeration cost,carbon emission cost,time penalty cost and transportation cost.Fourthly,a hybrid ant colony algorithm is designed,and the feasible solution obtained by genetic algorithm is used as the initial pheromone of the ant colony algorithm.The improved hybrid ant colony algorithm overcomes the shortcomings of traditional ant colony algorithm,such as slow initial convergence speed and missing initial pheromone,while retaining the robustness and positive feedback of ant colony algorithm,and the design of the algorithm is reasonable.Finally,taking the cold chain distribution of fresh agricultural products of H enterprise as an example,the designed hybrid ant colony algorithm was used to solve the constructed mathematical model.It is found that the hybrid ant colony algorithm is superior to the basic ant colony algorithm in the optimization speed and distribution cost control,and the cost is basically in line with the actual situation.