Study on the radiation of central city in the border area of provinces based on Voronoi diagram: A case study of Yulin city in Shaanxi province

The important indicator to measure an city´s urban centrality is the radiation of it. This study establish an evaluation index system, calculate the extent of radiation of Yulin and the cities around it in the border area of Shaanxi-Gansu-Ningxia-Inner Mongolia and Shanxi province, use Voronoi diagram to determine the scope of Yulin city. The part of the north and the south administrative regions are not classified as The extent of radiation of Yulin, this regions become confliction areas between Yulin and surrounding cities. The city of Yulin should pay more attention on the space of industry and urban construction, expand the sphere of influence.