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Social stratification and housing wealth inequality in transitional urban China
Chengdong Yi,Yuyao Li,Yourong Wang,Haiyuan Wan 서울시립대학교 도시과학연구원 2021 도시과학국제저널 Vol.25 No.1
As the Chinese economy continues to transform, housing wealth has gradually become the single largest asset in most urban households. At the same time, housing wealth inequality has worsened, and housing stratification has become a major form of social stratification in the country. However, there is no empirical evidence of temporal changes in housing wealth inequality and their implications on social stratification. Pooling three waves of survey data from the 1995, 2008, and 2013 iterations of the Chinese Household Income Project, we present a dynamic image of housing wealth inequality in urban China. The results suggest that housing wealth inequality decreased initially and increased later. To further illustrate how housing wealth is stratified by social groups, we conducted regression analyses and structural tests, which revealed three main results: the education level of the household head has an increasingly positive impact on housing wealth inequality; a household head with superior occupational status generally has an advantage in terms of possession of housing wealth with no evidence that this advantage diminishes during the transitional period; and income has a significant, positive impact on housing wealth, and this effect exhibited an increasing trend over time. These results imply that the temporal changes in housing wealth inequality exacerbated the social stratification in transitional urban China.
Dianwei Qian,Shiwen Tong,Chengdong Li 한국전자통신연구원 2016 ETRI Journal Vol.38 No.5
This paper presents a control scheme for the leader-following formation of multiple robots. The control scheme combines the sliding mode control (SMC) method with the nonlinear disturbance observer (NDOB) technique. The formation dynamics suffer from uncertainties because the individual robots are uncertain. Concerning such formation uncertainties, the leader-following formation dynamics are modeled. Assuming that the formation uncertainties have an unknown boundary, an NDOB-based observer was designed to estimate the formation uncertainties. A sliding surface containing the observer outputs has been defined. Regarding the sliding surface, an SMC-based controller was investigated to form uncertain robots. A sufficient condition in the sense of the Lyapunov theory was proven such that the formation system is asymptotically stable. Herein, some comparison results between the sole SMC method and the second-order SMC method are presented to demonstrate the effectiveness and feasibility of the control scheme for multiple robots in the presence of uncertainties.