1. School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710119, China
2. School of Computer Science, Shaanxi Normal University, Xi'an 710119, China
3. School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510006, China
4. The Technical Quality Department of Hangzhou Hollysys Automation Co., Ltd. Xi'an Branch, Xi'an 710077, China