1. Faculty of Mechanical Engineering, Institute of Computer Science and Production Management , University of Zielona Góra , ul. prof. Z. Szafrana 4, 65-516 Zielona Góra , Poland
2. Mathematical Modeling Department, Mechanical and Mathematical Faculty , Ivan Franko University of Lviv , 1 Universytetska str., Ukraine 79000 Lviv , Ukraine
3. Centre of Mathematical Modeling of Ukrainian National Academy of Sciences , 15 Dudaeva Str., Ukraine 70005 , Lviv , Ukraine