1. Ph.D. Student, Budapest Univ. of Technology and Economics (BUTE), Müegyetem rkp. 3, H-1111 Budapest, Hungary.
2. Ph.D. Student, Dept. of Systems and Environmental Engineering, Systems Engineering Laboratory (SEL), Univ. of Oulu, Finland.
3. Assistant Professor, Dept. of Hydrodynamic Systems, Budapest Univ. of Technology and Economics (BUTE), Müegyetem rkp. 3, H-1111 Budapest, Hungary (corresponding author).