| As a crucial link in the international cold-chain system and a key switching node in the cold-chain transportation service network,the port will supply storage and transportation services for frozen and fresh goods.Compared with the traditional logistics,uncertainty is usually a big risk a program faces in the stages of the port cold-chain operation for properties of the goods themselves,environmental conditions and human factors,which makes more demands on port.Cold-chain berths,yards for refrigerated containers and cold storages play a significant role in the process of imports and exports for frozen and fresh goods,whose effective programming and rational exploitation can improve the cold-chain logistics circulation rate,reduce the decay rate and logistics costs in the process of logistics transportation.Based on the key components and uncertainty analysis theory of the cold-chain system of the port,this paper constructs a model of the optimization of the scale of port cold-chain infrastructure under uncertain conditions and determines the cold-chain transportation plan of the goods and the temperature control strategy of the storage unit.Then,the optimization theory and method of the infrastructure scale for port cold chain under uncertainties is investigated,and it can give the optimization method of port cold-chain infrastructure scale quantitatively,which provides the theoretical support for guiding port cold-chain infrastructure planning and improving the transformation efficiency of goods in the port cold-chain system.First,considering the perishable charateristics of fresh goods,from the viewpoint of the whole process of the cold-chain system,a cold-chain transportation service network optimization model from production area to sales area with harbor as a significant conversion node is constructed,where transportation cost and quality degradation are both chosen as objective functions.It provides the NSGA-II multi-objective genetic solutions for how to determine cold-chain network volume distribution and transportation modes selection under uncertainties.The model focuses on the method of the optimization allocation for container-load freight and non-container-load freight to provide the initial input for the optimization of port cold-chain infrastructure scale,and minimizes the total cold-chain transportation cost while meeting the requirement of goods quality under different seasonsSecondly,considering the uncertainty of the reefer ship arrival and the backlog loss of fresh goods,an optimization model for the scale of dedicated berths for port cold-chain system under uncertaities is constructed,targeting at minimizing the total cost for the constructing period and the operating period.The simulation optimization method based on tabu search algorithm is proposed to solve the model of optimal scale of dedicated berths for port cold-chain system.This model also makes analysis of the influence on the berth scale of different additional loss ratio of goods.Again,aiming at the cargoes with differernt properties and different production laws,considering the influence of uncertainty factors on cold storage,an optimization model for the storage of port cold-chain system is established for port cold-storage nodes in cold-chain transportation service network,with the goal of maximizing the profit of the cold warehouse or the yard of refrigerated containers.A two-stage stochastic planning method is used to scientifically plan the cold-storage capacity of the port cold-chain system and a simulated-annealing algorithm with the penalty function is applied to solving the model.This model can gain the optimal scale of port cold storages and reefer container yards,and provide references for the temperature control of cold storages.At last,in the case of a port cold-chain system for container-load freight and non-container-load freight,verify the feasibility and the validity of the optimization method of the scale of port cold-chain infrastructure under the uncertainties. |
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