Private investors and governments need to cooperate in public–private partnership (PPP) projects but the private investors may be in pursuit of their own profit by conducting defaulting behaviors which causes various environmental problems and economic risks. However, the information asymmetry between them makes it difficult to supervise the behaviors of private investors. The development of internet and social media creates new environment for the information spread and people are using new media increasingly in the current society, providing an inexpensive and viable way for the public to participate in PPP projects. We constructed a dynamic evolutionary model to analyze the behaviors strategies of governments and private investors in the new media era and then analyzed how important factors influence the behavior trends of governments and private investors. These findings could provide meaningful insight to improve supervision status by using the new media environment and predict the behaviors of governments and private investors in PPP projects, which would be conductive for the governments to supervise the private investors in PPP projects more efficiently.

In order to improve the living environment and meet the daily needs of residents, the Chinese government is vigorously promoting the policy of old community renovation, which is closely related to the life quality and happiness of the residents. However, conflicts often occur between residents and contractors in the construction stage of old community renovation projects as a result of failing to satisfy residents’ demands. This paper uses evolutionary game theory to explore this issue. An evolutionary game model between contractor and resident is established, and then nine different strategy evolution scenarios are derived based on it. Numerical simulation is conducted to analyze the influencing factors of conflict between resident and contractor in the construction stage. It is found that construction cost, reputation, and loss caused by resident’s protest are important factors for the contractor to consider resident’s demand. Protesting cost, probability of winning the protest, and increase in benefit of winning protest exert great impact on the evolution of resident’s strategy decision on whether to protest. The paper can help to predict and affect the strategy evolution of the two parties, which will promote smooth progress of old community renovation.

Shanghai is one of the fastest-growing metropolises and the first city in China to implement mandatory waste classification. Waste classification policy of Shanghai has attracted widespread attention since its implementation in July 2019. However, previous papers have not focused on online public attitudes surrounding the implementation of a waste classification policy in Shanghai. In order to fill this gap, this paper explored the dynamic evolution of online public attitudes towards waste classification in Shanghai by using sentiment analysis technology and topic modeling technology. It was found that the proportion of negative posts each month was about 20%; therefore, online public sentiment towards waste classification in Shanghai was generally positive. Compared with the first three months of policy implementation, the public sentiment towards Shanghai’s waste classification became more positive, with the exception of two special periods. Negative posts in July 2019 mainly discussed waste’s environmental hazards and policy provisions. New topics in negative posts in later months focused on some specific problems, including the process of throwing away wet waste, the allocated throwing times, the number of waste cans, takeaway meal disposal, and gathering activities. Improving the factors causing the negative sentiments in the posts will help the government better implement the policy. The paper will help the government to receive higher public support for the waste classification policy in Shanghai. The present findings also have great reference significance for other cities.