415 research outputs found

    On integral conditions in the mapping theory

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    It is established interconnections between various integral conditions that play an important role in the theory of space mappings and in the theory of degenerate Beltrami equations in the plane.Comment: 15 pages, changes related to Corollary 3.2, see (3.28

    Surface Roughness and Hydrodynamic Boundary Conditions

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    We report results of investigations of a high-speed drainage of thin aqueous films squeezed between randomly nanorough surfaces. A significant decrease in hydrodynamic resistance force as compared with predicted by Taylor's equation is observed. However, this reduction in force does not represents the slippage. The measured force is exactly the same as that between equivalent smooth surfaces obeying no-slip boundary conditions, but located at the intermediate position between peaks and valleys of asperities. The shift in hydrodynamic thickness is shown to be independent on the separation and/or shear rate. Our results disagree with previous literature data reporting very large and shear-dependent boundary slip for similar systems.Comment: Revised versio

    Dirichlet problem for Poisson equations in Jordan domains

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    We study the Dirichlet problem for the Poisson equations △u(z) = g(z) with g ∈ Lp, p > 1, and continuous boundary data φ : ∂D → ℝ in arbitrary Jordan domains D in ℂ and prove the existence of continuous solutions u of the problem.Мы изучаем задачу Дирихле для уравнений Пуассона △u(z) = g(z) с g ∈ Lp, p > 1, и непрерывными граничными данными φ : ∂D → ℝ в произвольных жордановых областях D ⊂ ℂ и доказываем существование непрерывных решений u этой задачи.Ми вивчаємо задачу Дiрихле для рiвнянь Пуасона △u(z) = g(z) с g ∈ Lp, p > 1, та неперервними граничними даними φ : ∂D → ℝ в довiльних жорданових областях D ⊂ ℂ та доводимо iснування неперервних рiшень u цiєї задач

    On the theory of the Beltrami equation

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    We study ring homeomorphisms and, on this basis, obtain a series of theorems on existence of the so-called ring solutions for degenerate Beltrami equations. A general statement on the existence of solutions for the Beltrami equations is formulated extending earlier results.Вивчаються кільцеві гомеоморфізми, i на цій підставі отримано низку теорем про існування так званих кільцевих розв'язків вироджених рівнянь Бельтрамі. Сформульовано загальне твердження про існування розв'язків рівнянь Бельтрамі, що узагальнює більш ранні результати

    To the theory of semi-linear Beltrami equations

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    The present paper is devoted to the study of semi-linear Beltrami equations which are closely relevant to the corresponding semi-linear Poisson type equations of mathematical physics on the plane in anisotropic and inhomogeneous media. In its first part, applying completely continuous ope\-ra\-tors by Ahlfors-Bers and Leray--Schauder approach, we prove existence of regular solutions of the semi-linear Beltrami equations with no boundary conditions. Moreover, here we derive their representation through solutions of the Vekua type equations and generalized analytic functions with sources. As consequences, it is given a series of applications of these results to semi-linear Poisson type equations and to the corresponding equations of mathematical physics describing such phenomena as diffusion with physical and chemical absorption, plasma states and stationary burning in anisotropic and inhomogeneous media. The second part of the paper contains existence, representation and regularity results for nonclassical solutions to the Hilbert (Dirichlet) boundary value problem for semi-linear Beltrami equations and to the Poincare (Neumann) boundary value problem for semi-linear Poisson type equations with arbitrary boundary data that are measurable with respect to logarithmic capacity.Comment: 28 pages. arXiv admin note: text overlap with arXiv:2107.1066

    On Dirichlet problem for degenerate Beltrami equations with sources

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    The present paper is devoted to the study of the Dirichlet problem Reω(z)φ(ζ){\rm{Re}}\,\omega(z)\to\varphi(\zeta) as zζ,z\to\zeta, zD,ζD,z\in D,\zeta\in \partial D, with continuous boundary data φ:DR\varphi :\partial D\to\mathbb R for Beltrami equations ωzˉ=μ(z)ωz+σ(z)\omega_{\bar{z}}=\mu(z) \omega_z+\sigma (z), μ(z)<1|\mu(z)|<1 a.e., with sources σ:DC\sigma :D\to\mathbb C in the case of locally uniform ellipticity. In this case, we establish a series of effective integral criteria of the type of BMO, FMO, Calderon-Zygmund, Lehto and Orlicz on singularities of the equations at the boundary for existence, representation and regularity of solutions in arbitrary bounded domains DD of the complex plane C\mathbb C with no boun\-da\-ry component degenerated to a single point for sources σ\sigma in Lp(D)L_p(D), p>2p>2, with compact support in DD. Moreover, we prove in such domains existence, representation and regularity of weak solutions of the Dirichlet problem for the Poisson type equation div[A(z)u(z)]=g(z){\rm div} [A(z)\nabla\,u(z)] = g(z) whose source gLp(D)g\in L_p(D), p>1p>1, has compact support in DD and whose mat\-rix valued coefficient A(z)A(z) guarantees its locally uniform ellipticity.Comment: 31 pages. arXiv admin note: substantial text overlap with arXiv:2111.1037
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