The population density in megacities in China gives rise to challenges, such as traffic congestion and soaring housing prices. A trend of leaving primate cities can be observed as well as a population increase in secondary cities. These trends might point to an urbanisation transition from the primate city stage to the secondary city stage. Research is needed to determine at which stage of urbanisation China currently resides, and who are migrating across the different levels of cities in this stage. In order to answer these questions, the current study combines the theory of differential urbanisation and migrant selectivity, and analyses city-level migration patterns and demographic characteristics of migrants across the urban hierarchy. The findings indicate that China is currently in the intermediate primate city stage, where the upward migration across the urban hierarchy is driven by younger adults with higher education and income, and a lower likelihood of marriage or parenthood. Building upon global evidence, this research further extends the theory of differential urbanisation by incorporating migrant selectivity into the interpretation of urbanisation stages. It reveals that educated migrants tend to concentrate and move up the urban hierarchy in the primate city stage but might deconcentrate during the secondary and small city stages. This study offers practical insights for policymakers at the national and city levels to develop population growth plans, adjust targeted migration policies and respond to future urbanisation processes.@en

The cooperative behavior of residents is complex and influenced by their complicated social relationships. This complexity is especially noticeable in neighborhood renewal, so the government does not know how to promote residents' cooperative behavior. Therefore, this study proposes an agent-based model (ABM) to investigate the development of residents' cooperative behavior in neighborhood renewal. Based on a questionnaire survey among residents of old neighborhoods in China, the parameters of ABM were determined in this study. Then, controlled experiments were conducted to investigate the effects of general trust among residents and government control of neighborhood renewal on cooperation patterns in renewal projects. In addition, this study examines the effects of different types of social network structures (small-world, scale-free, and random networks) on the evolution of residents' cooperative behaviors. The simulation results show that when residents' initial willingness to agree to renewal projects is high, their close social relationships need to be managed by the government to achieve better outcomes. Conversely, if initial willingness is low, residents' close relationships may pose a challenge to the government. In addition, government-led renewal projects should be encouraged to a greater extent. This study confirms that the different social network structures have an influence on the development of residents' cooperative behavior. The results of this study provide concrete evidence for understanding the factors that contribute to the emergence of residents' cooperative behavior and for studying the effects of government intervention on neighborhood renewal projects. In addition, the results of this study provide theoretical support for future studies of residents' social network structures.

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