1. Laboratory Team of Distributed Microcomputer Systems, Department of Mathematics, University of Ioannina, University Campus, 45110 Ioannina, Greece
2. Systems Reliability and Industrial Safety Laboratory, Institute for Nuclear and Radiological Sciences, Energy, Technology and Safety, NCSR Demokritos, Ag. Paraskevi, 15341 Athens, Greece
3. School of Rural and Surveying Engineering, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece