1. Department of Electrical and Computer Engineering; National University of Singapore; 4 Engineering Drive 3 Singapore 117583
2. Information Technology University (ITU); 346-B, Ferozepur Rd Lahore 54000 Pakistan
3. Department of Physics; Harbin Institute of Technology; Harbin 150001 China
4. NUS Graduate School for Integrative Sciences and Engineering; National University of Singapore; 28 Medical Drive Singapore 117456