1. School of Automation, Guangdong Polytechnic Normal University, Guangzhou 510450, P. R. China
2. Department of Electrical and Computer Engineering, University of California Santa Cruz, CA 95064, USA
3. School of Electronics and Information, Guangdong Polytechnic Normal University, Guangzhou 510660, P. R. China
4. School of Automation, Guangdong Polytechnic Normal University, The Guangzhou Key Laboratory of Intelligent Building, Equipment Information Integration and Control, Guangzhou 510660, P. R. China
5. School of Engineering, Electrical, Electronic and Computer Engineering, The University of Western Australia, Perth 6009, Australia