1. Computer Technology Institute and Press "Diophantus", University of Patras, Patras, Greece
2. Department of Computer Engineering, Technological Institute of Central Greece, Lamia, Greece
3. Computer Technology Institute & Press “Diophantus”, Computer Engineering and Informatics Department, University of Patras, Patras, Greece
4. Computer Engineering and Informatics Department, University of Patras, Patras, Greece