1. College of Energy and Power Engineering, Lanzhou University of Technology, 287 Langongping Road, Qilihe District, Lanzhou City, Gansu, China; College of Engineering, Nihon University, Koriyama, Fukushima 963-8642, Japan
2. College of Energy and Power Engineering, Lanzhou University of Technology, 287 Langongping Road, Qilihe District, Lanzhou City, Gansu, China
3. College of Engineering, Nihon University, Koriyama, Fukushima 963-8642, Japan