[1] Xidian Univ, Minist Educ, Key Lab Elect Equipment Struct Design, Xian 710071, Shaanxi, Peoples R China
[2] Xidian Univ, Sch Mechanoelect Engn, Ctr Complex Syst, Xian 710071, Shaanxi, Peoples R China
[3] Univ Lancaster, Sch Comp & Commun, InfoLab21, Lancaster LA1 4YW, England
[4] Philips Res, NL-5656 AE Eindhoven, Netherlands