1. Wuhan National Laboratory for Optoelectronics and the Key Laboratory of Information Storage System of Ministry of Education of China, Huazhong University of Science and Technology, Wuhan, Hubei, China
2. School of Computer Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China
3. Department of Computer and Information Sciences, Temple University, Philadelphia, PA, USA
4. Department of Electrical and Computer Engineering, Virginia Commonwealth University, Richmond, VA, USA