Ústav matematiky
Browse
Recent Submissions
Now showing 1 - 5 of 77
- ItemOptimal Stabilization in Systems of Linear Differential Equations(Dnipro National University, 2024-06-30) Khusainov, Denys Ya.; Diblík, Josef; Shatyrko, Andrej; Hahurin, ZhenyaThis article considers the optimal stabilization problems for complex dynamical systems, which can be described in terms of linear differential equations. At the beginning of the article, general provisions on optimal stabilization and the application of the apparatus of optimal Lyapunov functions for the purpose of solving the formulated problem are given. To ensure consistency and easier understanding of the obtained results, the systems with scalar control are considered first. The main results were obtained for systems with n-dimensional control and the presence of a diagonal matrix in the quality criteria. Finally, the conditions are extended to the case when a matrix of the general form is used in the quality criterion.
- ItemMultiple normalized solutions for the planar Schrödinger–Poisson system with critical exponential growth(Springer Nature, 2024-02-16) Chen, Sitong; Radulescu, Vicentiu; Tang, XianhuaThe paper deals with the existence of normalized solutions for the following Schr & ouml;dinger-Poisson system with -constraint: { -Delta u+lambda u+mu(log||& lowast;u2)u=(e(u2-)1-u2)u,x is an element of R-2, integral R(2)u(2)dx=c, where mu>0,lambda is an element of R , will arise as a Lagrange multiplier and the nonlinearity enjoys critical exponential growth of Trudinger-Moser type. By specifying explicit conditions on the energy level c, we detect a geometry of local minimum and a minimax structure for the corresponding energy functional, and prove the existence of two solutions, one being a local minimizer and one of mountain-pass type. In particular, to catch a second solution of mountain-pass type, some sharp estimates of energy levels are proposed, suggesting a new threshold of compactness in the -constraint. Our study extends and complements the results of Cingolani-Jeanjean (SIAM J Math Anal 51(4): 3533-3568, 2019) dealing with the power nonlinearity a|u|p-2uin the case ofa>0andp>4, in the case of and , which seems to be the first contribution in the context of normalized solutions. Our model presents some new difficulties due to the intricate interplay between a logarithmic convolution potential and a nonlinear term of critical exponential type and requires a novel analysis and the implementation of new ideas, especially in the compactness argument. We believe that our approach will open the door to the study of other -constrained problems with critical exponential growth, and the new underlying ideas are of future development and applicability.
- ItemNon-autonomous double phase eigenvalue problems with indefinite weight and lack of compactness(London Mathematical Society, 2024-02-08) Tianxiang, Gou; Radulescu, VicentiuIn this paper, we consider eigenvalues to the following double phase problem with unbalanced growth and indefinite weight,-Delta pau-Delta qu=lambda m(x)|u|q-2uinRN,$$\begin{equation*} \hspace*{3pc}-\Delta _pa u-\Delta _q u =\lambda m(x)|u|{q-2}u \quad \mbox{in} \,\, \mathbb {R}<^>N, \end{equation*}$$where N > 2$N \geqslant 2$, 1{0, 1}(\mathbb {R}N, [0, +\infty))$, a not equivalent to 0$a \not\equiv 0$ and m:RN -> R$m: \mathbb {R}N \rightarrow \mathbb {R}$ is an indefinite sign weight which may admit non-trivial positive and negative parts. Here, Delta q$\Delta _q$ is the q$q$-Laplacian operator and Delta pa$\Delta _pa$ is the weighted p$p$-Laplace operator defined by Delta pau:=div(a(x)| backward difference u|p-2 backward difference u)$\Delta _pa u:=\textnormal {div}(a(x)|\nabla u|{p-2} \nabla u)$. The problem can be degenerate, in the sense that the infimum of a$a$ in RN$\mathbb {R}N$ may be zero. Our main results distinguish between the cases p
- ItemGroundstates of the planar Schrodinger-Poisson system with potential well and lack of symmetry(Cambridge University Press, 2023-06-06) Liu, Zhisu; Radulescu, Vicentiu; Zhang, JianjunThe Schrodinger-Poisson system describes standing waves for the nonlinear Schrodinger equation interacting with the electrostatic field. In this paper, we are concerned with the existence of positive ground states to the planar Schrodinger-Poisson system with a nonlinearity having either a subcritical or a critical exponential growth in the sense of Trudinger-Moser. A feature of this paper is that neither the finite steep potential nor the reaction satisfies any symmetry or periodicity hypotheses. The analysis developed in this paper seems to be the first attempt in the study of planar Schrodinger-Poisson systems with lack of symmetry.
- ItemMultiplicity of solutions for nonlinear coercive problems(Elsevier, 2023-12-01) Diblík, Josef; Galewski, Marek; Radulescu, Vicentiu; Šmarda, ZdeněkWe are concerned in this paper with problems that involve nonlinear potential mappings satisfying condition (S) and whose potentials are coercive. We first provide mild sufficient conditions for the minimizing sequence in the Weierstrass-Tonelli theorem in order to have strongly convergent subsequences. Next, we establish a three critical point theorem which is based on the Pucci-Serrin type mountain pass lemma and which is an infinite dimensional counterpart of the Courant theorem. Ricceri-type three critical point results then follow. Some applications to Dirichlet boundary value problems driven by the perturbed Laplacian are given in the final part of this paper.