1. University of Naples “Parthenope”,Dept. of Science and Technology,Naples,Italy
2. University of Madrid Carlos III,Dept. of Computer Science,Madrid,Spain
3. NEC Laboratories of America Inc.,Princeton,NJ,USA
4. Inst. for High Performance Computing and Networking (ICAR), National Research Council (CNR),Naples,Italy
5. University of Naples “Federico II”,Dept. of Mathematics and Applications,Naples,Italy