Dana Simian , University Lucian Blaga of Sibiu, Faculty of Sciences, Department of Computer Science, Sibiu, Romania E-mail: dana.simian@ulbsibiu.ro Ioana Moisil , University Lucian Blaga of Sibiu, "Hermann Oberth" Faculty of Engineering, Sibiu, Department of Computer Science and Automatic Control, Sibiu, Romania E-mail: ioana.moisil@ulbsibiu.ro Milan Tuba , University of Belgrade, Serbia E-mail: tubamilan@ptt.yu Daniela Marinescu , University Transilvania Brasov, Romania E-mail: mdaniela@unitbv.ro Stefka Fidanova , Bulgarian Academy of Science, Institute of Parallel Computing, Bulgaria E-mail: stefka@bas.bg