1. School of Mathematics and Statistics, Northwestern Polytechnical University, Xi’an, Shaanxi 710072, P. R. China
2. MOE Key Laboratory for Complexity Science in Aerospace, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, P. R. China
3. Research & Development Institute of Northwestern Polytechnical University in Shenzhen, Sanhang Science & Technology Building, No. 45th, Gaoxin South 9th Road, Nanshan District, Shenzhen City 518063, P. R. China