1. Ph.D. Student, Dept. of Power and Energy, Northwestern Polytechnical Univ., Xi’an 710072, China.
2. Professor, Dept. of Power and Energy, Northwestern Polytechnical Univ., Xi’an 710072, China.
3. Research Associate Professor, Dept. of Power and Energy, Northwestern Polytechnical Univ., Xi’an 710072, China (corresponding author).