1. College of Computer Science and Technology, Huaqiao University, Xiamen 361021, China
2. State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi’an Jiaotong University, Xi’an 710049, China
3. College of Architecture, Huaqiao University, Xiamen 361021, China
4. Department of Mathematics and Statistics, San Diego State University, San Diego, CA 92182, USA