1. Tianjin Key Laboratory of Intelligence Computing and Novel Software Technology, Engineering Research Center of Learning-Based Intelligent System, Ministry of Education, Tianjin University of Technology, Tianjin 300384 China (e-mail: xialooking@163.com).
2. Tianjin Key Laboratory of Intelligence Computing and Novel Software Technology, Engineering Research Center of Learning-Based Intelligent System, Ministry of Education, Tianjin University of Technology, Tianjin 300384 China (e-mail: lyp@zurp.date).
3. Tianjin Key Laboratory of Intelligence Computing and Novel Software Technology, Engineering Research Center of Learning-Based Intelligent System, Ministry of Education, Tianjin University of Technology, Tianjin 300384 China (e-mail: wltjut08@126.com).
4. School of Science, Beijing University of Posts and Telecommunication, Beijing 100876 China (e-mail: hjli@amss.ac.cn).