Results 51 to 60 of about 539 (137)
Mathematical Methods in the Applied Sciences, Volume 49, Issue 4, Page 3353-3384, 15 March 2026.ABSTRACT The article examines a boundary‐value problem in a bounded domain Ωε$$ {\Omega}_{\varepsilon } $$ consisting of perforated and imperforate regions, with Neumann conditions prescribed at the boundaries of the perforations. Assuming the porous medium has symmetric, periodic structure with a small period ε$$ \varepsilon $$, we analyze the limit ...
Taras Melnyk
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Electronic Journal of Differential Equations, 2001 We find sufficient conditions for systems of functions to be Riesz bases in $L_2(0,1)$. Then we improve a theorem presented in [13] by showing that a ``standard'' system of solutions of a nonlinear boundary-value problem, normalized to 1, is a Riesz ...
Peter E. Zhidkov
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Karpatsʹkì Matematičnì Publìkacìï, 2019 In this article we investigate a problem with nonlocal boundary conditions which are multipoint perturbations of mixed boundary conditions in the unit square $G$ using the Fourier method. The properties of a generalized transformation operator $R: L_2(G)
Ya.O. Baranetskij +3 more
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Semiclassical inequalities for Dirichlet and Neumann Laplacians on convex domains
Communications on Pure and Applied Mathematics, Volume 79, Issue 3, Page 762-822, March 2026.Abstract We are interested in inequalities that bound the Riesz means of the eigenvalues of the Dirichlet and Neumann Laplacians in terms of their semiclassical counterpart. We show that the classical inequalities of Berezin–Li–Yau and Kröger, valid for Riesz exponents γ≥1$\gamma \ge 1$, extend to certain values γ<1$\gamma <1$, provided the underlying ...
Rupert L. Frank, Simon Larson
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International Journal of Mathematics and Mathematical Sciences, 2012 Almost orthogonal frames have been introduced and studied. It has been proved that a bounded almost orthogonal frame satisfies Feichtinger conjecture. Also, we prove that a bounded almost orthogonal frame contains a Riesz basis.
Virender, A. Zothansanga, S. K. Kaushik
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Potential trace inequalities via a Calderón‐type theorem
Journal of the London Mathematical Society, Volume 113, Issue 3, March 2026.Abstract In this paper, we develop a general theoretical tool for the establishment of the boundedness of notoriously difficult operators (such as potentials) on certain specific types of rearrangement‐invariant function spaces from analogous properties of operators that are easier to handle (such as fractional maximal operators).
Zdeněk Mihula +2 more
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Karpatsʹkì Matematičnì Publìkacìï, 2018 We study a problem with periodic boundary conditions for a $2n$-order differential equation whose coefficients are non-self-adjoint operators. It is established that the operator of the problem has two invariant subspaces generated by the involution ...
Ya.O. Baranetskij +3 more
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Vestnik Samarskogo Gosudarstvennogo Tehničeskogo Universiteta. Seriâ: Fiziko-Matematičeskie Nauki, 2014 A nonlocal problem for mixed type equation with a singular coefficient and the spectral parameter is formulated in the field, which hyperbolic part is vertical half-strip and elliptic part is rectangle.
Anton A Abashkin
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Electronic Journal of Differential Equations, 2015 This article concerns the Riesz basis property and the stability of a damped Euler-Bernoulli beam with nonuniform thickness or density, that is clamped at one end and is free at the other.
K. Augustin Toure +2 more
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On the Riesz Basisness of Systems Composed of Root Functions of Periodic Boundary Value Problems
Abstract and Applied Analysis, 2015 We consider the nonself-adjoint Sturm-Liouville operator with q∈L1[0,1] and either periodic or antiperiodic boundary conditions. We obtain necessary and sufficient conditions for systems of root functions of these operators to be a Riesz basis in L2[0,1]
Alp Arslan Kıraç
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