1. School of Energy, Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China
2. School of Energy, Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China;
3. Key Laboratory of Condition Monitoring and Control for Power Plant Equipment of Ministry of Education, North China Electric Power University, Beijing 102206, China
4. Key Laboratory of Condition Monitoring and Control for Power Plant Equipment of Ministry of Education, North China Electric Power University, Beijing 102206, China e-mail:
5. Mechanical and Industrial Engineering, 3131 Seamans Center, The University of Iowa, Iowa City, IA 52242-1527