1. Department of Mathematical Modeling and Calculation MathematicsTver State University Sadoviy per. 35 Tver 170102 Russia
2. Federal Research Center ‘Institute of Applied Physics of the RAS’Mechanical Engineering Research Institute of the Russian Academy of Sciences 85 Belinsky Street Nizhny Novgorod 603024 Russia
3. Faculty of RadiophysicsNizhny Novgorod Lobachevsky State University 23, Gagarin av. Nizhny Novgorod 603024 Russia