1. Professor, MOE Key Laboratory of Regional Energy Systems Optimization, S-C Energy and Environmental Research Academy, North China Electric Power Univ., Beijing 102206, China; formerly, Environmental Systems Engineering Program, Faculty of Engineering and Applied Science, Univ. of Regina, Regina, Saskatchewan S4S 0A2, Canada (corresponding author).
2. Professor, MOE Key Laboratory of Regional Energy Systems Optimization, S-C Energy and Environmental Research Academy, North China Electric Power Univ., Beijing 102206, China; formerly, Environmental Systems Engineering Program, Faculty of Engineering and Applied Science, Univ. of Regina, Regina, Saskatchewan S4S 0A2, Canada.