5 papers
Theoretical study of nonlinear wave equations with combined power-type nonlinearities with variable coefficients
Milena Dimova, Natalia Kolkovska, Nikolai Kutev
In this paper, we study the initial boundary value problem for the nonlinear wave equation with combined power-type nonlinearities with variable coefficients. The global behavior o…
Improved Hardy inequality with logarithmic term
Nikolai Kutev, Tsviatko Rangelov
New Hardy type inequality with double singular kernel and with additional logarithmic term in a ball is proved. As an application an estimate from below of…
Control properties for heat equation with double singular potential
Nikolai Kutev, Tsviatko Rangelov
The aim of this article is to study the noncontrollability of the heat equation with double singular potential at an interior point and on the boundary of the domain.
Minimal surfaces in foliated by circles
N. Kutev, V. Milousheva
We deal with minimal surfaces in the unit sphere , which are one-parameter families of circles. Minimal surfaces in foliated by circles were first investigated by Riema…
Complete Integrability of a Nonlinear Elliptic System, Generating Bi-Umbilical Foliated Semi-Symmetric Hypersurfaces in
N. Kutev, V. Milousheva
We find explicitly all bi-umbilical foliated semi-symmetric hypersurfaces in the four-dimensional Euclidean space.