[1] Beihang Univ, Sch Mech Engn & Automat, Beijing 100191, Peoples R China
[2] Chinese Acad Sci, Beijing Inst Nanoenergy & Nanosyst, CAS Ctr Excellence Nanosci, Beijing Key Lab Micronano Energy & Sensor, Beijing 101400, Peoples R China
[3] Tsinghua Univ, Dept Comp Sci & Technol, Beijing 100084, Peoples R China