1. School of Software; Dalian University of Technology; Dalian China
2. Key Laboratory for Ubiquitous Network and Service Software of Liaoning Province; Dalian China
3. Department of Computer and Information Science; Fordham University; 441 East Fordham Road, JMH 340 Bronx NY U.S.A.
4. Department of Computer Science and Information Engineering; Chung Hua University; Hsinchu Taiwan