1. School of Computer and Information Engineering, Zhejiang Gongshang University, Hangzhou 310018, China
2. Department of Computing, East Tennessee State University, Johnson City, TN 37614-1266, USA
3. Department of Computer Science and Engineering, Zhangzhou Normal University, Zhangzhou, China
4. School of Information Systems, Al Imam University, Riyadh, Saudi Arabia
5. Scientific Publishing Center, Bahrain University, 32038 Sakhir, Bahrain
6. Graduate School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan