Svetlin G. Georgiev works on various aspects of mathematics. His current research focuses on harmonic analysis, ordinary differential equations, partial differential equations, fractional calculus, time scale calculus, integral equations, numerical analysis, differential geometry, and dynamic geometry. Khaled Zennir: was born in Algeria 1982. He received his PhD in Mathematics in 2013 from Sidi Bel Abbès University, Algeria (Assist. professor). He is now associate Professor at Qassim University, KSA. His research interests lie in Nonlinear Hyperbolic Partial Differential Equations: Global Existence, Blow-Up, and Long Time Behavior.