Beijing Inst Technol, Ctr Energy & Environm Policy Res, Beijing, Peoples R China.;Beijing Inst Technol, Sch Management & Econ, Beijing, Peoples R China.;Texas A&M Univ, Prod & Efficiency Measurement Lab, College Stn, TX USA.;Texas A&M Univ, Dept Ind & Syst Engn, College Stn, TX USA..