Analysis Of Container Port Selection And Network Equilibrium Based On Ant Colony Algorithms

For three decades after the reform and opening-up policy,as an open window,port has been playing a more and more important role in the development of national economy.The fast development of container ports and the increase of cargo owner's wharf,however,have made competition fiercer and resulted in surplus of port productive capacity.On the one hand,it causes the decline of operation profit;on the other hand,it brings about enormous waste on port resource and in sequence,it weakens the sustainable development of regional economy.In order to keep development and go through the fierce competition,stable supply of goods is a necessity.It's of important theoretical value and practical significance for sustainable and healthy development of port to understand the evaluation procedures and results,to research in both macrostructure and microstructure of port network,and to establish and improve basic theory on port network development.The topic thus has become an important problem to study.Theoretically based upon the equilibrium analysis of container port selection and port network,this dissertation establishes optimization model combining intelligence algorithm,and researches into the port selection and the freight flow allocation in port network,with comprehensive consideration of the characteristics of cargo owner port selection and market competition。The main research results are summarized as below:Firstly,it puts forth a new optimization model for cargo owner port selection, aiming at the probability maximum of cargo owner port selection,which means that the greater the probability is,the easier it is to be selected by the cargo owner.This model, considering comprehensively three main factors of cargo owner port selection and combining qualitative and quantitative calculation,is easy in operation.Since it's an optimization model of multi-targets combination with complex structure,which is difficult to be solved via traditional methods,here ant colony optimization(ACO),a new evolution algorithm,is used to search for the shortest route in network.Meanwhile, in order to improve the search efficiency of ant colony algorithm,this thesis develops a new strategy to update the increased pheromone-ANT-Weight strategy of ACO. Lastly,the model and algorithm are tested through examples,and the same results from both theoretical analysis and the test verify the effectiveness of the model and algorithm.Secondly,the basis upon which cargo owners select port is fundamental to the structure of port network.The problem whether port network is built reasonably will directly affect cargo owners' profit.The static port network aiming at maximum probability of cargo owner port selection is set up in the precondition that the selected port is of unlimited throughput and the difference in rates of port charge is small.In practical transportation,however,the pressure from port throughput limitation,port congestion and jam is more and more severe,which requires a certain rule to distribute the cargo practically into each course.To meet this need,here the dynamic port network comes into being.In order to settle the problem of cargo flow allocation,an increment distribution method in transportation distribution model is adopted.According to this method,divide cargo flow between OD averagely into many equal parts,and allocate these parts in circulation into the network.As calculation to search for the shortest path is the most basic and crucial,a new kind of increment distribution model based on coarse-granular parallel ant colony algorithms is set forth.This model realizes the optimum distribution of cargo flow in dynamic port network,which makes the dynamic port network reach equilibrium.Lastly,after applying this model and algorithm into certain regional container port network,we get the optimized effect of container port network layout.Thirdly,as an essential part of transportation network,port network contributes to the development of national economy.It's hence of practical significance to analyze harmonious development of port network to avoid the waste of social resource, especially today when scientific development concept is advocated.This dissertation puts forth the fuzzy aggregated evaluation model based upon set occurrence statistics methodology.This model forms a set occurrence statistics sequence by interval estimation from experts' qualitative analysis,and further calculates the evaluated value of indicators quantitatively,which solves the problem of uncertainty in fuzzy evaluation. So this method is operative and practical in the evaluation of port network harmonious development.Lastly,this method is tested by examples and its result shows that it's possible to have more reliable evaluation. At the end of this thesis,a sum-up is made,and problems in need of further research are put forward.