[1] Shanghai Univ Elect Power, Sch Automat Engn, Shanghai 201306, Peoples R China
[2] Shanghai Univ Elect Power, Lib, Shanghai 201306, Peoples R China
[3] Peking Univ, Sch Software & Microelect, Beijing 102600, Peoples R China
[4] Norwegian Univ Sci & Technol, Fac Informat Technol & Elect Engn, Dept Comp Sci, N-7034 Trondheim, Norway