南沙岛礁及周边港口可达性评价模型研究
石伟1,2,3, 苏奋振1,3, 周成虎1,3, 吴文周1,2,3

Research on accessibility model of Nansha Islands and surrounding seaports
SHI Wei1,2,3, SU Fenzhen1,3, ZHOU Chenghu1,3, WU Wenzhou1,3
图5 南沙23个岛屿对周边海域的4级控制区域
Fig. 5 Control areas and classes of 23 islands in Nansha