Funding for this research was provided by:
National Natural Science Foundation of China (71872019, 71974107, 91646102, L1824040, L1924062)
Beijing Natural Science Foundation (9182013)
Beijing Social Science Foundation (17GLC058)
Fundamental Research Funds for the Central Universities (2018XKJC04)
Ministry of Education in China Project of Humanities and Social Sciences (16JDGC011)
Volvo-supported Green Economy and Sustainable Development Tsinghua University (20153000181)
Article History
Received: 6 November 2019
First Online: 8 June 2020