1. Department of Mathematics, School of Sciences Henan University of Technology Zhengzhou Henan 450001 China
2. School of Behavioural, Management and Social Sciences University of Twente P.O. Box 217 Enschede 7500 AE The Netherlands
3. Department of Applied Mathematics University of Twente P.O. Box 217 Enschede 7500 AE The Netherlands
4. Graduate School of Management Management & Science University Shah Alam Selangor Darul Ehsan 40100 Malaysia