Greater contradiction and conflict among urban green space, the development of social economy and the environment have occurred in Beijing. However, few studies have been conducted that consider the three subsystems as a whole. In this study, we defined sustainable development of green space (SDGS) as the coordinated development of the urban green system, social economy, and environment. Based on the datasets from 2000 to 2015, we forecast the SDGS in Beijing under multiple scenarios based on real-world policies using a system dynamics model. We found that the historical SDGS value increased to its highest level in 2012, but declined slightly by 2015. Second, the forecasted SDGS values declined over time in all scenarios, but the decline was greater in scenarios placing a high priority on economic development. In these scenarios, the performance of the indices only improved in certain subsystems. The simulation shows the implementation of the four policies proposed by the government failed to improve the overall level of SDGS in Beijing. This study could provide support for decision-making designed to improve the overall condition of urban green space in Beijing through integrated forecast and scenario simulation.
Using observations of the superconducting gravimeter GWR‐C032 at station Wuhan, the tidal gravity parameters reflecting the characteristics of the Earth's interior medium are obtained based on the harmonic analysis after variable preprocessing to the raw data. Meanwhile the gravity loading are calculated using the loading theory and a numerical integral convolution technique based on various global ocean tide models developed by methods of the altimetry technology and finite element with consideration of tidal gauge data as constraints. The loading corrections are carried out for tidal gravity parameters in diurnal and semidiurnal wave bands, respectively in order to investigate the adaptability of global ocean tide models. The numerical results show that the efficiencies of loading correction reach to 91% (O1, NAO99) and 92% (M2, ORI96) for instance. The average efficiencies of the loading corrections obtained with 11 oceanic models for four main constituents (O1, K1, M2 and S2) are 86%, 70%, 73% and 84%, respectively. And the discrepancies between amplitude factors and theoretical values decrease from (2.12%, 1.55%, 1.16% and 0.80%) to (0.31%, 0.39%, 0.34% and 0.08%), respectively. The comparison among various ocean models also shows that the loading correction efficiencies when using NAO99 and ORI96 models are higher than those when using other models. Additionally, other observations obtained with superconducting gravimeters at 7 stations in a network of the Global Geodynamic Project are also adopted to investigate the adaptability of the global ocean models. The results show that there exist obvious local tidal characteristics for different constituents in different ocean models and the earlier constructed SCW80 ocean model can still be used as an important reference in geodesy research.
Previous behavioral studies on urban structure have been limited by the scale, accuracy, or promptness in obtaining statistical data used for delimiting retail center boundaries and hierarchical analysis. Using a large amount of GPS-enabled taxi data from Guangzhou, China, this research attempts to delimit the boundaries of retailing centers and explore their hierarchical characteristics. The identified retailing centers are verified with economic census data, and the retailing hierarchical structure is identified through assessing trip summation, travel distance, and travel time. Among these indicators, trip summation reveals hierarchical characteristics best. The urban retailing hierarchical structure also reveals the centrality of urban Guangzhou.
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