[1] Xian Technol Univ, Sch Optoelect Engn, Xian 710021, Peoples R China
[2] North Carolina State Univ, Dept Mech & Aerosp Engn, Raleigh, NC 27695 USA
[3] Xi An Jiao Tong Univ, Sch Elect Sci & Engn, Fac Elect & Informat Engn, Elect Mat Res Lab,Key Lab,Minist Educ, Xian 710049, Peoples R China
[4] Xi An Jiao Tong Univ, Sch Elect Sci & Engn, Int Ctr Dielectr Res, Fac Elect & Informat Engn, Xian 710049, Peoples R China