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Railway is a fundamental transportation mode for medium and long-distance travel in China. China's railway transport network (CRTN) has become increasingly complex. Clarifying the structure of the CRTN and its robustness to failures is important for ensuring safe operations. This paper uses train schedule data to construct a railway physical network (RPN) and a train service network (TSN), and proposes a method to simulate the CRTN change processes under different attack strategies, clarify its robustness, and identify its backbone. The results show: First, the RPN is a typical scale-free and small-world network, while the TSN presents a complex hierarchical structure; Second, the RPN is robust to random attacks but vulnerable to targeted attacks, and attacks based on the betweenness centrality as evaluated in the RPN is the most effective mode; Third, the backbone network consists 62 cities including Beijing, Tianjin, and Shijiazhuang. [ABSTRACT FROM AUTHOR]

There are many challenges to achieving quality multiscalar displays of vector data in geographical information system (GIS). Acknowledging and making use of the differences between traditional cartographic generalization and multiscalar display in GIS, this paper focuses on novel approaches to the definition of small objects and the establishment of scale sequence. The ease of implementation and efficacy of the solutions proposed are exemplified and analyzed. Possibilities for further research into the multiscalar display of vector data in GIS are thereby suggested. [ABSTRACT FROM PUBLISHER]

This paper discusses extensions of GAP-trees from three aspects and its implementation based on non-topological structure in order to enhance access to large vector data sets. First of all, we apply cartographic generalization rules to build a generalization procedure of the GAP-tree, which makes coarse representations more consistent with human cognition. Second, we replace the three-dimensional (pseudo-) Reactive-tree index with a 2D R-tree index and a B-tree index to improve the system efficiency. Finally, we compress a binary GAP-tree into multi-way GAP-trees in order to reduce data redundancy. The shallower multi-way GAP-trees not only eliminate redundant data but also accelerate the system's response time. The extensions have been successfully implemented in PostgreSQL. A test of Beijing's land-use data at the 1:10 000 scale demonstrates that the extended GAP-trees are efficient, compact, and easy to implement. [ABSTRACT FROM AUTHOR]