1. School of Mechanics, Civil Engineering and Architecture, Northwestern Polytechnical University, Xi'an 710072, China
2. Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
3. The School of Systems Information Science, Future University Hakodate, 116-2 Kamadanakano-cho, Hakodate, Hokkaido 041-8655, Japan
4. School of Science, Northwestern Polytechnical University, Xi'an 710072, China
5. School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, Arizona 85287, USA