Research On Accessibility Model Of Island And Port Based On Gravity Model

Located in the southern part of the South China Sea,the Nansha Islands are not only the forefront of marine defense,but also an important base for the development of marine resources.They have important practical significance and long-term development for China's sovereign rights,economic development,and national defense security.Strategic significance.Limited by the island's own land area and other natural conditions,the carrying capacity and self-sustaining capacity of the Nansha Islands are relatively poor.To sustain the continuous activity of a large number of people,the island needs continuous supply from the outside world.As a special node connecting inland hinterland and marine transportation,the port has become an important link in the transportation system and social economic system.It analyzes the main ports of the countries around Nansha,so as to deepen the understanding of the ports along the route and improve the surrounding ports on the island The ability of the reef to transport resources is of great significance.This paper as a starting point in transportation port,as well as the destination of the reef,comprehensive consideration the transport and end point at the ends of the "quality",add port competitiveness and reef comprehensive value "quality factor",and the algorithm to automatically generate the shortest routes between nodes,through the establishment of water depth and ship cost classification of corresponding relations,this paper proposes a accessibility composite index based on gravity model,to measure the accessibility of the Nansha islands and the surrounding ports.Through calculation,the comprehensive competitiveness of 10 major ports in the surrounding countries and regions of Nansha and the comprehensive value of 20 islands and reefs in Nansha are obtained,and then the comprehensive accessibility between these ports and islands and reefs is calculated.In order to comprehensively analyze the impact of the respective comprehensive "quality" of ports and islands and reefs on accessibility,the results of the improved gravity model are compared with traditional accessibility measurement models.The difference in the accessibility of each port measured by the shortest time model is small.The weighted travel time model with the island and reef comprehensive strength index shows that the difference in accessibility difference between ports has increased,indicating that the island and reef comprehensive value index The accessibility to islands and reefs has a certain impact.The results of the improved gravity model combining the comprehensive strength of the port and the island and reef show a large difference in the accessibility changes between the ports,which fully shows that the comprehensive strength of the port and the island and reef are the evaluation of the port to the island and reef The indispensable factors of accessibility have made the differences between the ports rapidly expand.