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Understanding the processes and mechanisms of the spatial spread of epidemics is essential for making reasonable judgments on the development trends of epidemics and for adopting effective containment measures. Using multi-agent technology and big data on population migration, this paper constructed a city-based epidemic and mobility model (CEMM) to stimulate the spatiotemporal of COVID-19. Compared with traditional models, this model is characterized by an urban network perspective and emphasizes the important role of intercity population mobility and high-speed transportation networks. The results show that the model could simulate the inter-city spread of COVID-19 at the early stage in China with high precision. Through scenario simulation, the paper quantitatively evaluated the effect of control measures "city lockdown" and "decreasing population mobility" on containing the spatial spread of the COVID-19 epidemic. According to the simulation, the total number of infectious cases in China would have climbed to 138,824 on February 2020, or 4.46 times the real number, if neither of the measures had been implemented. Overall, the containment effect of the lockdown of cities in Hubei was greater than that of decreasing intercity population mobility, and the effect of city lockdowns was more sensitive to timing relative to decreasing population mobility.

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Urbanization is a comprehensive concept, a trinity process that is based on the interactions and mutual influences among the population urbanization, economic urbanization and space urbanization, in which, people are the central and leading players in this process, while economic activities serve as the driving force and space is the carrier-the physical or material setting as well as the product. So the coordination among these processes is crucial for a country or region′s sustainable development. China is experiencing rapid growth of cities and a surge in urban population, with the basic national condition of many people and little land, which calls for a systematic study of the issue of coordinated urbanization from theoretical, methodological and practical perspectives. Based on the concept of urbanization and non-coordination of urbanization, this article built a quantitative method to identify and evaluate the urbanization and non-coordination of urbanization, and made an empirical analysis in China between 2000 and 2008. The results show that the non-coordination overall level of China′s urbanization declined during the study period, because population urbanization, economic urbanization, and space urbanization exhibited different trajectories of change. This study also reveals that performance assessment system, household registration system, and urban land expropriation system, etc., are the main affecting factors. At the end, we put forward some suggestions to achieve sustainable development of China′s urbanization from the aspects of improving the local government′s objective function, implementing the urban planning system, enforcing public participation aspects and so on.

Crime is one of the major concerns facing Chinese cities. Using crime data compiled at police precinct level in 2008, this research examines spatial patterns of violent crimes in Changchun, and explores the relationship between the spatial distribution of violent crimes and neighborhood characteristics. Crime rates are applied as a measure of the intensity of violent crimes. Spatial statistics and geographic information systems are used to detect violent crime hot spots, or statistically significant locales of high violent crime rates in Changchun. A multiple linear regression model is calibrated to assess the impacts of contextual neighborhood characteristics on violent crimes. The analytical results demonstrate that the risk or intensity of violent crimes is strongly concentrated in the central city area, and neighborhood socioeconomic, demographic, especially land use characteristics are effective in accounting for the spatial variation in the distribution of violent crimes across the city of Changchun. These findings are largely in line with the routine activities theory, social disorganization theory, and the framework of crime prevention through environmental design, which emphasize the importance of opportunities, local social context, and environmental design in shaping the spatial pattern of and reducing urban crimes.