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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]

The article presents the discussion on rivers being the most accessible freshwater resource for human beings. Topics include indispensable role in water storage, allocation and purification, shipping, power generation, and culture and support services; and problem of water shortage in some areas becoming increasingly prominent restricting the social and economic development.

Urban agglomeration research has received increasing attention in China's national development strategies, and has become a hot topic in academic research. This study develops a theoretical framework that explores the formation mechanism and expansion process of urban agglomerations from the perspective of industrial evolution, and identifies the development issues and their causes by taking Yangtze Delta and Beijing-Tianjin-Hebei urban agglomerations as case studies. In the process of urban agglomeration formation within a free market, as has happened in Yangtze Delta region, the central city develops first, its secondary industry is then transferred to its neighboring cities, and the work division and cooperation with the neighboring cities is gradually established. However, in the 1990s, aiming to become an international metropolis, Beijing implemented a series of administrative policies to encourage the reduction of the secondary industry and the development of the tertiary industry, before its secondary industry were fully developed and transferred to its neighboring cities. This delayed the integration process and the development of the Beijing-Tianjin-Hebei urban agglomeration. This study builds a good foundation for the construction of the theoretical system's urban agglomeration study, and provides references for decision making in an urban agglomeration development. [ABSTRACT FROM AUTHOR]

Floorspace spatial development is indisputably the most essential indicator to reflect the spatial distribution of activities especially in mega cities. To forecast the housing floorspace distribution, a three-step Floorspace Development Model (FDM) is developed in this study based on indicators of permissible development constrains, floorspace areas, and house rents. Beijing is selected as the case study area in consideration of its high house price and limited space. Since government plays a key role in the estate development in China, the housing floorspace is estimated through three steps including unconstrained floorspace estimation, constrained floorspace estimation, and zonal floorspace allocation. This FDM model is applicable to forecast the developers' decisions based on market rules and government policies, which combines China's special conditions with prediction method perfectly for the first time. Based on this model, floorspace distribution and development prediction can be achieved, laying a solid foundation for assessments of servicing, industrial and educational floorspace development and distribution at urban scale especially mega cities in China. [ABSTRACT FROM AUTHOR]

This study developed a migration model, termed the inter-city migration model (IcMM), based on the "push-pull" theory to model China's inter-city population migration. The IcMM is comprised of three sub-models: the pull, push, and distance impedance models. The IcMM simulates two-way inter-city migration based on cities' pull factors, push factors, and distance impedance. The IcMM is a strict implementation of the "push-pull" theory. Model verification shows that it can achieve good results in simulating China's inter-city migration. The three sub-models included in the IcMM are loosely coupled and easy to expand. The regional applicability and extension of the proposed model is also discussed. • A migration model was developed to simulate population migration between city-pairs in China. • The model simulates migration based on city push and pull factors along with distance impedance. • The three loosely-coupled sub-models make the proposed model easy to operate and expand. • Influencing factors and mechanisms of intercity migration in China are identified. [ABSTRACT FROM AUTHOR]

This study uses an equal population cartogram to plot the intercity railway network in Mainland China. [ABSTRACT FROM AUTHOR]

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]

The key to studying urban sustainable development depends on quantifying stores, efficiencies of urban metabolisms and capturing urban metabolisms' mechanisms. This paper builds up the metabolic emergy account and quantifies some important concepts of emergy stores. Emphasis is placed on the urban metabolic model based on the slack based model (SBM) method to measure urban metabolic efficiencies. Urban metabolic mechanisms are discussed by using the regression method. By integrating these models, this paper analyzes the urban metabolic development in Beijing from 2001 to 2010. We conclude that the metabolic emergy stores of Beijing increased significantly from 2001 to 2010, with the emergy imported accounting for most of the increase. The metabolic efficiencies in Beijing have improved since the 2008 Olympic Games. The population, economic growth, industrial structures, and environmental governance positively affect the overall urban metabolism, while the land expansion, urbanization and environmentally technical levels hinder the improving of urban metabolic efficiencies. The SBM metabolic method and the regression model based on the emergy analysis provide insights into the urban metabolic efficiencies and the mechanism. They can promote to integrate such concepts into their sustainability analyses and policy decisions. [ABSTRACT FROM AUTHOR]