1. a Electrical Engineering Department, the City College, City University of New York, Convent Ave & 140th Street, New York, NY 10031, USA; Department of Mechanical and Electronic Engineering, School of Automation Science and Electrical Engineering, Beihang University, Beijing 100083, P. R. China
2. b Electrical Engineering Department, the City College, City University of New York, Convent Ave & 140th Street, New York, NY 10031, USA
3. c Department of Mechanical and Electronic Engineering, School of Automation Science and Electrical Engineering, Beihang University, Beijing 100083, P. R. China
4. d Electrical Engineering Department, the City College, City University of New York, Convent Ave & 140th Street, New York, NY 10031, USA