The effects of a building＇s density on urban flows are investigated using a CFD model with the RNG k - ε turbulence closure scheme. Twenty-seven cases with different building＇s density parameters （e.g., building a...The effects of a building＇s density on urban flows are investigated using a CFD model with the RNG k - ε turbulence closure scheme. Twenty-seven cases with different building＇s density parameters （e.g., building and street-canyon aspect ratios） are numerically simulated. As the building＇s density parameters vary, different flow regimes appear. When the street canyon is relatively narrow and high, two counterrotating vortices in the vertical direction are generated. The wind speed along streets is mainly affected by the building＇s length. However, it is very difficult to find or generalize the characteristics of the street-canyon flows in terms of a single building＇s density parameter. This is because the complicated flow patterns appear due to the variation of the vortex structure and vortex number. Volume-averaged vorticity magnitude is a very good indicator to reflect the flow characteristics despite the strong dependency of flows on the variation of the building＇s density parameters. Multi-linear regression shows that the volume-averaged vorticity magnitude is a strong function of the building＇s length and the street-canyon width. The increase in the building＇s length decreases the vorticity of the street-canyon flow, while, the increase in the street- canyon width increases the vorticity.展开更多
A nonlinear analysis of urban evolution is made by using of spatial autocorrelation theory. A first-order nonlinear autoregression model based on Clark’s negative exponential model is proposed to show urban populatio...A nonlinear analysis of urban evolution is made by using of spatial autocorrelation theory. A first-order nonlinear autoregression model based on Clark’s negative exponential model is proposed to show urban population density. The new method and model are applied to Hangzhou City, China, as an example. The average distance of population activities, the auto-correlation coefficient of urban population density, and the auto-regressive function values all show trends of gradual increase from 1964 to 2000, but there always is a sharp first-order cutoff in the partial auto- correlations. These results indicate that urban development is a process of localization. The discovery of urban locality is significant to improve the cellular-automata-based urban simulation of modeling spatial complexity.展开更多
In this paper, we present an overview of urban practice in China since the late 1970s and come up with a refreshed concept regarding "new towns" as existing in a widely different politico-economic context. W...In this paper, we present an overview of urban practice in China since the late 1970s and come up with a refreshed concept regarding "new towns" as existing in a widely different politico-economic context. With the urbanization of capital being the theoretical backbone of this paper, we attempt to reveal basic laws inherent in the emergence and proliferation of various forms of urban spaces within a rapidly modernizing country. Considered from various viewpoints such as land institutions, national policy designs, and the fi nancial capital and bank system, our paper covers: a historical overview of China's post-reform new towns, a theoretical framework to explain related phenomena, empirical approaches to interpreting the contributory factors, and a theoretical outline for further research.展开更多
Since the 1990s, with peopte＇s living requirements getting more and more advanced, the speed of the residential commercialization gets higher and higher, which promotes the residential construction deeply. To some ex...Since the 1990s, with peopte＇s living requirements getting more and more advanced, the speed of the residential commercialization gets higher and higher, which promotes the residential construction deeply. To some extent, the construction of residential area has accelerated the urbanization and impacted the progress of urban renewal. It has already happened in most Chinese major cities and is progressing right now. But it has not been shown clearly in existing researches how and how deeply it impacts the development of urban construction. This article discussed how the development of urban residential space impacted the progress of urban renewal, based on the theoretic researches of urban renewal, taking the otd town of Nanjing for example, and using the methods of quantitative evidence method and kernel density estimation.展开更多
Mathematical models show that the urbanization process is an important factor affecting the transfer of labor among economic sectors.The regression results using time-series data since China’s reform and opening up s...Mathematical models show that the urbanization process is an important factor affecting the transfer of labor among economic sectors.The regression results using time-series data since China’s reform and opening up show that there is significant positive correlation between urbanization and the service industry’s ability to create jobs.However,there is no Granger Causation between them.Therefore,China should shift from focusing on industry park construction to paying more attention to improving urban functions by increasing their employment density of urban services.展开更多
OBJECTIVE: To understand the distribution of prevalence rate of osteoporosis in the middle - aged and elderly in parts of China. METHODS: Bone mineral density (BMD) was measured and questionnaires were taken for 5593 ...OBJECTIVE: To understand the distribution of prevalence rate of osteoporosis in the middle - aged and elderly in parts of China. METHODS: Bone mineral density (BMD) was measured and questionnaires were taken for 5593 people aged above 40 years in five administrative areas in China selected by the stratified - multi - steps - cluster sampling method. RESULTS: The total prevalence rate of osteoporosis was 16.1%. The prevalence rate among males was 11.5% and among females was 19.9% (P展开更多
基金funded by the Korea Meteorological Administration Research and Development Program under Grant CATER 2007–3307
文摘The effects of a building＇s density on urban flows are investigated using a CFD model with the RNG k - ε turbulence closure scheme. Twenty-seven cases with different building＇s density parameters （e.g., building and street-canyon aspect ratios） are numerically simulated. As the building＇s density parameters vary, different flow regimes appear. When the street canyon is relatively narrow and high, two counterrotating vortices in the vertical direction are generated. The wind speed along streets is mainly affected by the building＇s length. However, it is very difficult to find or generalize the characteristics of the street-canyon flows in terms of a single building＇s density parameter. This is because the complicated flow patterns appear due to the variation of the vortex structure and vortex number. Volume-averaged vorticity magnitude is a very good indicator to reflect the flow characteristics despite the strong dependency of flows on the variation of the building＇s density parameters. Multi-linear regression shows that the volume-averaged vorticity magnitude is a strong function of the building＇s length and the street-canyon width. The increase in the building＇s length decreases the vorticity of the street-canyon flow, while, the increase in the street- canyon width increases the vorticity.
基金Under the auspices of the National Natural Science Foundation of China (No. 40371039)
文摘A nonlinear analysis of urban evolution is made by using of spatial autocorrelation theory. A first-order nonlinear autoregression model based on Clark’s negative exponential model is proposed to show urban population density. The new method and model are applied to Hangzhou City, China, as an example. The average distance of population activities, the auto-correlation coefficient of urban population density, and the auto-regressive function values all show trends of gradual increase from 1964 to 2000, but there always is a sharp first-order cutoff in the partial auto- correlations. These results indicate that urban development is a process of localization. The discovery of urban locality is significant to improve the cellular-automata-based urban simulation of modeling spatial complexity.
文摘In this paper, we present an overview of urban practice in China since the late 1970s and come up with a refreshed concept regarding "new towns" as existing in a widely different politico-economic context. With the urbanization of capital being the theoretical backbone of this paper, we attempt to reveal basic laws inherent in the emergence and proliferation of various forms of urban spaces within a rapidly modernizing country. Considered from various viewpoints such as land institutions, national policy designs, and the fi nancial capital and bank system, our paper covers: a historical overview of China's post-reform new towns, a theoretical framework to explain related phenomena, empirical approaches to interpreting the contributory factors, and a theoretical outline for further research.
文摘Since the 1990s, with peopte＇s living requirements getting more and more advanced, the speed of the residential commercialization gets higher and higher, which promotes the residential construction deeply. To some extent, the construction of residential area has accelerated the urbanization and impacted the progress of urban renewal. It has already happened in most Chinese major cities and is progressing right now. But it has not been shown clearly in existing researches how and how deeply it impacts the development of urban construction. This article discussed how the development of urban residential space impacted the progress of urban renewal, based on the theoretic researches of urban renewal, taking the otd town of Nanjing for example, and using the methods of quantitative evidence method and kernel density estimation.
文摘Mathematical models show that the urbanization process is an important factor affecting the transfer of labor among economic sectors.The regression results using time-series data since China’s reform and opening up show that there is significant positive correlation between urbanization and the service industry’s ability to create jobs.However,there is no Granger Causation between them.Therefore,China should shift from focusing on industry park construction to paying more attention to improving urban functions by increasing their employment density of urban services.
文摘OBJECTIVE: To understand the distribution of prevalence rate of osteoporosis in the middle - aged and elderly in parts of China. METHODS: Bone mineral density (BMD) was measured and questionnaires were taken for 5593 people aged above 40 years in five administrative areas in China selected by the stratified - multi - steps - cluster sampling method. RESULTS: The total prevalence rate of osteoporosis was 16.1%. The prevalence rate among males was 11.5% and among females was 19.9% (P
