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Gini Index for Cities: A Preliminary Study on Regional Differences of Chinese City Size Distribution
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作者 Liu Wangbao & Zheng Bohong Department of Architecture and Urban Planing, Central South University, Changsha 410075, Hunan 《Chinese Journal of Population,Resources and Environment》 2004年第4期33-36,共4页
City size distribution is of interest because of a number of key stylized facts, including notably Zipf's law for cities and the importance of urban primacy. But a new and more efficient method Gini index can be u... City size distribution is of interest because of a number of key stylized facts, including notably Zipf's law for cities and the importance of urban primacy. But a new and more efficient method Gini index can be used for calculating regional city size distribution. This paper begins by developing a calculation method for the Gini index, dividing the whole country into 26 areas and then calculating each area's Gini index value. Based on these calculation results, this paper gives a preliminary study on regional differences of its city size distribution and the dynamics. 展开更多
关键词 Gini index city size distribution regional differences
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Aerosol size distributions during haze episodes in winter in Jinan, China 被引量:8
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作者 Yuwei Sun Xuehua Zhou Wenxing Wang 《Particuology》 SCIE EI CAS CSCD 2016年第5期77-85,共9页
Number concentrations and distributions of 10-10,000 nm particles in a large city (Jinan) in the North China Plain were measured in winter 2009. The mean number concentrations of nucleation mode (10-20 nm), Aitken... Number concentrations and distributions of 10-10,000 nm particles in a large city (Jinan) in the North China Plain were measured in winter 2009. The mean number concentrations of nucleation mode (10-20 nm), Aitken mode (20-100 nm), and accumulation mode (100-1000 nm) particles, as well as total particles were 925, 6898, 2476, and 10,299cm-3, respectively. Two severe haze episodes, with elevated concentrations caused by pollutants accumulating, were observed. Accumulation mode particle concen- trations were significantly higher during the episodes than on clear days, and nucleation mode particle concentrations were pronouncedly higher on clear days than during the episodes. The peaks of domi- nant number, surface area, and mass size distributions were around 30-50, 200-300, and 200-400 rim, respectively, both during the haze episodes and on clear days, but elevated mass and surface area con- centrations around 500-600 nm were also observed during the haze episodes, suggesting these particles had significant contributions to haze formation. These particles were probably formed through larger droplets in cloud and fog evaporating. Two new particle formation events, probably triggered by strong photochemical processes on clear days and significant traffic emissions during haze episode 2, were found. Significant insights were made into haze formation in a oolluted Chinese urban area. 展开更多
关键词 Aerosol size distributions Hazy and clear days Polluted city China
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Sequential city growth: Theory and evidence from the US 被引量:2
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作者 SHENG Kerong SUN Wei FAN Jie 《Journal of Geographical Sciences》 SCIE CSCD 2014年第6期1161-1174,共14页
City growth patterns are attracting more attention in urban geography studies. This paper examines how cities develop and grow in the upper tail of size distribution in a large-scale economy based on a theoretical mod... City growth patterns are attracting more attention in urban geography studies. This paper examines how cities develop and grow in the upper tail of size distribution in a large-scale economy based on a theoretical model under new economic geography framework and the empirical evidence from the US. The results show that cities grow in a sequential pattern. Cities with the best economic conditions are the first to grow fastest until they reach a critical size, then their growth rates slow down and the smaller cities farther down in the urban hierarchy become the fastest-growing ones in sequence. This paper also reveals three related features of urban system. First, the city size distribution evolves from low-level balanced to primate and finally high-level balanced pattern in an inverted U-shaped path. Second, there exist persistent discontinuities, or gaps, between city size classes. Third, city size in the upper tail exhibits conditional convergence characteristics. This paper could not only contribute to enhancing the understanding of urbanization process and city size distribution dynamics, but also be widely used in making effective policies and scientific urban planning. 展开更多
关键词 sequential city growth discontinuities city size distribution conditional convergence
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