1. Master, College of Automation Engineering, Nanjing Univ. of Aeronautics and Astronautics, Nanjing 210016, P.R. China.
2. Professor, College of Automation Engineering, Nanjing Univ. of Aeronautics and Astronautics, Nanjing 210016, P.R. China (corresponding author).
3. Professor, College of Automation Engineering, Nanjing Univ. of Aeronautics and Astronautics, Nanjing 210016, P.R. China.
4. Professor, Dept. of Electrical and Computer Engineering, Univ. of Virginia, Charlottesville, VA 22903.