Scopus İndeksli Yayınlar Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/8651

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Access Right: Open AccessInstitution Author: search.filters.institutionAuthor.Ugurlu, Ekin

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Now showing 1 - 7 of 7
  • Article
    Citation - WoS: 3
    Citation - Scopus: 3
    Left-Definite Hamiltonian Systems and Corresponding Nested Circles
    (Tubitak Scientific & Technological Research Council Turkey, 2023) Ugurlu, Ekin
    This work aims to construct the Titchmarsh-Weyl M(A)-theory for an even-dimensional left-definite Hamiltonian system. For this purpose, we introduce a suitable Lagrange formula and selfadjoint boundary conditions including the spectral parameter A. Then we obtain circle equations having nesting properties. Using the intersection point belonging to all the circles we share a lower bound for the number of Dirichlet-integrable solutions of the system.
  • Article
    Citation - WoS: 4
    Citation - Scopus: 4
    Discrete Left-Definite Hamiltonian Systems
    (Wilmington Scientific Publisher, Llc, 2023) Ugurlu, Ekin
    In this paper we consider an even-dimensional discrete Hamiltonian system on the set of nonnegative integers in the left-definite form. Using the inertia indices of the hermitian form related with the solutions of the equation we construct some maximal subspaces of the solution space. After constructing some ellipsoids preserving nesting properties we introduce a lower bound for the number of Dirichlet-summable solutions of the equation. Moreover we introduce a limit-point criterion.
  • Article
    Citation - WoS: 1
    Citation - Scopus: 1
    A New Hamiltonian System
    (Academic Press inc Elsevier Science, 2020) Ugurlu, Ekin
    This paper aims to share a new first-order differential equation that contains the continuous analogous of the orthogonal polynomials on the unit-circle. We introduce some basic results on the system and solutions of the system. Using nested-circle approach we introduce the possible number of square-integrable solutions of the system. At the end of the paper we share a limit-point criteria for the two-dimensional system of equations. (C) 2020 Elsevier Inc. All rights reserved.
  • Article
    Citation - WoS: 5
    Citation - Scopus: 5
    On the Eigenvalues of Second-Order Boundary-Value Problems
    (Wilmington Scientific Publisher, Llc, 2020) Ugurlu, Ekin
    In this paper we investigate the properties of eigenvalues of some boundary-value problems generated by second-order Sturm-Liouville equation with distributional potentials and suitable boundary conditions. Moreover, we share a necessary condition for the problem to have an infinitely many eigenvalues. Finally, we introduce some ordinary and Frechet derivatives of the eigenvalues with respect to some elements of the data.
  • Article
    Citation - WoS: 4
    Citation - Scopus: 4
    Singular Hamiltonian System With Several Spectral Parameters Ii: Odd-Order Case
    (Academic Press inc Elsevier Science, 2019) Ugurlu, Ekin
    In this paper we deal with a singular Hamiltonian system of odd-order with several spectral parameters and we investigate the behavior of the solution of this system at singular point with the aid of the characteristic function theory. Moreover, some results have been introduced for the Weyl-Titchmarsh function for some special Hamiltonian systems of odd-order with several spectral parameters. (C) 2019 Elsevier Inc. All rights reserved.
  • Article
    Citation - WoS: 16
    Citation - Scopus: 17
    Third-Order Boundary Value Transmission Problems
    (Tubitak Scientific & Technological Research Council Turkey, 2019) Ugurlu, Ekin
    In this paper, we consider some third-order operators with transmission conditions. In particular, it is shown that such operators are formally symmetric in the corresponding Hilbert spaces and we introduce the resolvent operators associated with the differential operators. After showing that the eigenvalues of the problems are real and discrete we introduce some ordinary and Frechet derivatives of the eigenvalues with respect to some elements of data.
  • Article
    Citation - WoS: 5
    Citation - Scopus: 5
    Singular Hamiltonian System With Several Spectral Parameters
    (Academic Press inc Elsevier Science, 2018) Ugurlu, Ekin
    In this paper, the Weyl-Titchmarsh theory has been constructed for the singular 2n-dimensional (even order) Hamiltonian system with several spectral parameters. In particular, we consider that the left end point of the interval is regular and the right end point of the interval is singular for the Hamiltonian system with several parameters. Using the nested circles approach, we prove that at least n-linearly independent solutions are squarly integrable with respect to some matrix functions. (C) 2018 Elsevier Inc. All rights reserved.