ISSN 2196-5625 CN 32-1884/TK
1. School of Economics and Management, North China Electric Power University, Beijing, China 2. Department of Electrical Engineering, The Hong Kong Polytechnic University, Hong Kong, China 3. School of Economics and Management, Shanghai University of Electric Power, Shanghai, China
the State Natural Sciences Fund (71071053), Beijing Energy Development and Research Base Projects and the RGC Hong Kong (GRF Project:PolyU 5279/09E) for carrying out the research work as reported in this paper are acknowledged.