1. Department of Nonstationary Vibrations, National Academy of Sciences of Ukraine, 2/10 Dm. Pozharskoho Street, 61046 Kharkiv, Ukraine
2. Department of Applied Mathematics and Numerical Methods, A.N. Podgorny Institute for Mechanical Engineering Problems, National Academy of Sciences of Ukraine, 2/10 Dm. Pozharskoho Street, 61046 Kharkiv, Ukraine