1. The School of Electrical Engineering and State Key Laboratory of Power Transmission Equipment &System Security and New Technology Chongqing University 174 Shazheng Street, Shapingba District Chongqing City 400044 P. R. China
2. The School of Chemistry and Chemical Engineering Chongqing University 174 Shazheng Street, Shapingba District Chongqing City 400044 P. R. China