Research On The Complexity And Optimization Of Transportation Network

The emergence of complex network theory affords us another new and good method to study complex systems. Many complex systems in the real world can be described as the complex networks, so, it is obvious that there are great values to research complex systems by complex network theory. At present, the hot field of complex network research is focused on the topologic properties, dynamics, synchronization, epidemic and modeling. In comparison with abstract networks, little attention is paid to spatial networks. All of the nodes and edges of the spatial networks have special geographical position, so, we must concentrate on their spatial characteristics and optimal plan under the restriction of geography conditions besides their topologic properties. Thus we can manage the spatial networks effectively and efficiently to improve their ability on resisting damage or attack.The dissertation introduces the complex network theory's development and research actuality of international and domestic. On the respect of searching spatial properties and the optimization of transportation network, the main works of the dissertation are as follows:First, by statistic analysis, a kind of complex networks whose degree distribution followed a Gaussian-like distribution was put forward. After case study, it was found that the degree distribution of Chinese Railway Network, National Highway System of some countries and Subway Networks of some cities all followed this type;Second, some big cities'subway networks were analyzed and it was found that they shared some common characteristics: tending to choose short edges, average degree is near to 2, clustering coefficient is almost 0 and large diameter. By computer simulation, it was also found that the structure of subway network was very like minimum spanning tree, and Beijing subway network was robust under random failure but frail under malice attack;Third, some countries'National Highway Systems were analyzed and it was found that they share follow common characteristics: tending to choose short edges, average degree is small than 4, small clustering coefficient and large diameter. Then, the genesis of above properties was analyzed from the respect of their spatial geographic characteristics;Fourth, the dynamic evolvement process of Chinese Highway Network under random failure and malice attack was demonstrated, after analyzing it's robustness and invulnerability, it was found that Chinese Highway Network are frailest under the malice attack of dynamic node betweenness descending order;Fifth, modified the model of highway network planning, the network topologic properties were added in the new model, and it satisfied true demand more. Then the optimization method of the highway network was also be modified from the respect of cost-benefit based on complex network and economic theory. At last, the structure of Chinese highway network was optimized by genetic algorithm, and the optimized structure was improved on invulnerability.