1. School of Electrical Engineering and Automation, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China
2. School of Control Science and Engineering, Shandong University, Jinan 250061, China
3. Key Laboratory of Pulp and Paper Science & Technology of Ministry of Education of China, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China