1. Ph.D. Candidate, School of Economics and Management, North China Electric Power Univ., Beijing 102206, China. ORCID: .
2. Associate Professor, Dept. of Economic Management, North China Electric Power Univ., Hebei 071003, China (corresponding author). ORCID: .
3. Professor, School of Economics and Management, North China Electric Power Univ., Beijing 102206, China.