[1] Ulyanovsk State Tech Univ, Fac Power Engn, Grp Numer & Appl Math Urgent Problems Energy & Po, Severny Venets St 32, Ulyanovsk 432027, Russia
[2] Ulyanovsk Inst Civil Aviat, Mozhaiskogo Str 8-8, Ulyanovsk 432071, Russia
[3] King Saud Univ, Coll Sci, Dept Math, POB 2455, Riyadh, Saudi Arabia
[4] Ural Fed Univ, Grp Modern Computat Methods, 19 Mira St, Ekaterinburg 620002, Russia
[5] TEI Sterea Hellas, Dept Automat Engn, 34400 Psachna Campus, Psachna, Greece
[6] Democritus Univ Thrace, Dept Civil Engn, Sect Math, Xanthi, Greece
[7] 10 Konitsis St, Athens 17564, Greece