1. School of Marine Science and Technology, Northwestern Polytechnical University, Xi’an, P.R. China;
2. School of Mechanical Engineering, Northwestern Polytechnical University, Xi’an, P.R. China;
3. Department of Mechanical Engineering, Embry-Riddle Aeronautical University, Daytona Beach, Florida, USA;
4. Research & Development Institute of Northwestern, Polytechnical University, Shenzhen, P.R. China