| With the rapid development of China's economy and the continuous improvement of people's consumption level,the consumption of fresh perishable foods have grown dramatically and cold chain transportation have been developed rapidly.Combined with the vastness of China's territory and the different transportation resources,the long-distance cold chain transportation will be inevitably accelerated.At present,China is vigorously promoting multimodal transport,which combines the advantages of multimodal transport in long-distance transportation.By combining cold-chain transport vehicles such as refrigerated containers,it can play an important role in the long-distance transport of perishable goods.The key to influencing the cost and efficiency of multimodal transport is the path selection problem.Therefore,based on the analysis of the special characteristics of multimodal transport of refrigerated containers for perishable goods,this paper systematically studies the construction and verification of multimodal transportation route selection model of perishable goods refrigerated containers,which mainly includes the following contents.(1)Summarized the quality change rule of perishable goods in the process of multimodal transport of refrigerated containers.In the multimodal transport environment,combining the quality change function of perishable goods with the"Time-Temperature-Tolerance" theory of storage and transportation reflecting the law of the quality of perishable goods in frozen state,it was proposed that the quality of perishable goods in the process of multimodal transport changes linearly with time.(2)Analyzed the refrigeration principle of refrigerated container and put forward the calculation method of refrigerating cost.By analyzing the working principle of mechanical refrigerated containers and combining analysis of the production and composition of cold consumption of refrigerated containers,the energy consumption relationship of "fuel consumption-electric energy consumption-cooling capacity" in the refrigeration process was summarized,and the calculation method of refrigeration cost based on cold consumption of refrigerated containers was established.(3)Constructed a nonlinear mathematical optimization model for the multi-commodity flow multimodal transport path selection of perishable goods refrigerated containers with time window for optimal cost.The cooling costs and cargo quality damage costs were taken into account in the optimization goal to fully reflect the characteristics of the transport process of refrigerated containers for perishable goods.In the model solution,the linearization technique is used to transform the nonlinear programming model into a 0-1 mixed integer linearprogramming model.A case study of a multimodal transport for domestic refrigerated containers for perishable goods was designed and solved using an exact solution algorithm to obtain a global optimal solution for a multi-commodity flow problem with a minimal generalized cost.Through sensitivity analysis,the impact of increasing railway travel speed and reducing rail freight rates on the generalized cost of multimodal transport of perishable goods was discussed,and the idea that improving rail transport efficiency is more operational than simply reducing freight rates was demonstrated. |
