1. MOE Key Laboratory of Hydraulic Machinery TransientsSchool of Power and Mechanical EngineeringWuhan University Wuhan Hubei 430072 China
2. Energy Storage and Distributed Resources DivisionLawrence Berkeley National Laboratory Berkeley CA 94720 USA
3. Wuhan National Laboratory for OptoelectronicsHuazhong University of Science and Technology Wuhan Hubei 430074 P. R. China