1. Li Juan Yang:
North China Electric Power University, College of Environmental Science and Engineering, Baoding 071003, China
2. Yi Zhao:
North China Electric Power University, College of Environmental Science and Engineering, Baoding 071003, China
3. Xi Xi Wang:
North China Electric Power University, College of Environmental Science and Engineering, Baoding 071003, China
4. Wei Sun:
North China Electric Power University, Department of Power Engineering, Baoding 071003, PR China