1. Professor, School of Civil Aviation, Northwestern Polytechnical Univ., Xi’an, Shaanxi 710072, China (corresponding author).
2. Professor, School of Engineering, Swinburne Univ. of Technology, Hawthorn, VIC 3122, Australia.
3. Professor, School of Aeronautics, Northwestern Polytechnical Univ., Xi’an, Shaanxi 710072, China.