1. Key Laboratory of Instrumentation Science and Dynamic Measurement, Ministry of Education, Taiyuan 030051, China
2. School of Science, North University of China, Taiyuan 030051, China
3. Science and Technology on Electronic Test and Measurement Laboratory, North University of China, Taiyuan 030051, China
4. Department of Mechanical Engineering, Louisiana State University, Baton Rouge, Louisiana 70803, USA