1. Graduate Student, School of Aeronautic Science and Engineering, Beihang Univ., No. 37 Xueyuan Rd., Haidian District, Beijing 100191, P.R. China.
2. Lecturer, College of Aerospace Engineering, Chongqing Univ., No. 144 Shazheng St., Shapingba District, Chongqing 400044, P.R. China (corresponding author).
3. Professor, School of Aeronautic Science and Engineering, Beihang Univ., No. 37 Xueyuan Rd., Haidian District, Beijing 100191, P.R. China.