1. School of Computer Science and Technology and Shaanxi Key Laboratory of Network Data Analysis and Intelligent Processing, Xi'an University of Posts and Telecommunications, Xi'an, Shaanxi, China
2. School of Computer Science and Communication Engineering, Jiangsu University, Zhenjiang, China
3. Dipartimento di Informatica, Università di Salerno, Via Giovanni Paolo II 132, Fisciano, Salerno, Italy
4. Shenzhen Institute for Advanced Study, University of Electronic Science and Technology of China, Shenzhen, China