Optimization Of Multi-transportation Organization Mode For Complicated Freight Flow

The category of transport goods is diverse. Differing in property, shape, value, batch measurement units and so on, different transport goods manifest different and hierarchical transport characteristics, which require different transport service level in cost, time, safety and frequency. Meanwhile, with the rapid development of social economy and continuous improvement of integrated transport network, multimodal transport of goods is development orientation and aim of modern transportation and logistics. In this context, oriented to complex freight flow, the dissertation highlights the influence of goods' transport characteristics on the optimization of multi-transportation organization mode, and selects the optimal transport spatial distribution, transport mode and transport path for different kinds of transport goods in the integrated transport network. The content and results of the dissertation are as follows:1) Based on the definition of cargo flow and the understanding of complexity, the dissertation puts forward the definition of complex cargo flow. Then it discusses the internal characteristics and external form of complex freight flow from the perspective of ontological complexity, and comparatively analyzes the complex and simple freight from the perspective of epistemological complexity. Finally it proposes the core problems on optimization of multi-transportation organization mode for complex freight flow.2) The dissertation points out the main problems of transport goods classification in China based on the comparative analysis of classification standards of transport goods in China and abroad. According to the coupling relationship of goods' transport attributes and transport service's attributes, the transport goods are divided into six categories by the quantitative theory III:time-sensitive goods, containerized goods, general break-bulk goods, hazardous goods, long and heavy goods, bulk goods.3) Based on the analysis of general shippers' decision-making psychology and mechanism on the option of transport mode and the transport path, the dissertation proposes the calculation model of transportation cost, opportunity cost, risk cost and time losing cost. Combined with the classification of transport goods, the generalized transport cost functions of time-sensitive goods, hazardous goods, general goods and bulk goods are established. 4) According to the related definition of comprehensive transport capability, the dissertation analyzes the concept, composition system, characteristics and influence factors of freight transport capacity of multi-transportation network and determines that the measurement period of it is one year. Base on the description of multi-transportation network, from the perspective of system optimization assignment of varying demand, it establishes bi-level programming model to calculate the freight transport capacity of multi-transportation network and designs heuristic algorithm based on the K-shortest path and minimum cost flow to solve the above model.5) With the demand matrix, the dissertation studies on the transportation organization mode, including the optimal transport mode and path for complex freight flow in multi-transportation network. In the application of traffic assignment theory and transport path optimization method, it establishes the multi-transportation mode option-assignment model based on the generalized transportation cost, and proposes Genetic Algorithm based on rational K-shortest path to solve the optimization model. Finally it takes the transportation organization mode optimization in the Three Gorges Region for empirical study.6) Without the demand matrix, the dissertation studies on the transportation organization mode, including the optimal transport spatial distribution and path for single freight flow in multi-transportation network. According to the mathematical model of classical transportation problem and transport path optimization method, it establishes the transport spatial distribution-equilibrium assignment model based on the generalized transportation cost, and proposes two-phase algorithm based on rational K-shortest path to solve the optimization model. Finally it takes the transportation organization mode optimization of import iron ore in the Yangtze River basin for empirical study.The dissertation deepens and perfects the optimization theory of freight multi-transportation organization from a new perspective, whose content and results can provide scientific basis for optimization decision on regional freight transport, and is significant for the improvement of transportation service level and the reduction of logistics cost.