1. Ph.D. Student, College of Aerospace Science and Engineering, National Univ. of Defense Technology, Changsha 410073, P.R. China (corresponding author).
2. Professor, College of Aerospace Science and Engineering, National Univ. of Defense Technology, Changsha 410073, P.R. China.
3. Ph.D. Student, College of Aerospace Science and Engineering, National Univ. of Defense Technology, Changsha 410073, P.R. China.
4. Assistant Professor, Dept. of Occupational and Environmental Health, Xiangya School of Public Health, Central South Univ., Changsha 410073, P.R. China.