V.N. Klyachkin - Dr. Sc. (Eng.), Professor, Department «Applied Mathematics and Informatics», Ulyanovsk State Technical University. E-mail: v_kl@mail.ru Yu.E. Kuvayskova - Ph. D. (Eng.), Associate Professor, Department «Applied Mathematics and Informatics», Ulya-novsk State Technical University. E-mail: u.kuvaiskova@mail.ru D.S. Bubyr - Post-graduate Student, Department «Applied Mathematics and Informatics», Ulyanovsk State Technical University. E-mail: bubir91@mail.ru