Results 31 to 40 of about 5,769 (217)

Stable factorization of the Calderón problem via the Born approximation

Journal of the London Mathematical Society, Volume 113, Issue 6, June 2026.
Abstract In this article, we prove the existence of the Born approximation in the context of the radial Calderón problem for Schrödinger operators. The Born approximation naturally appears as the linear component of a factorization of the Calderón problem; we show that the nonlinear part, obtaining the potential from the Born approximation, enjoys ...
Thierry Daudé, Fabricio Macià, Cristóbal Meroño, François Nicoleau   +3 more
wiley   +1 more source

A Unified Approach to Solvability and Stability of Multipoint BVPs for Langevin and Sturm–Liouville Equations with CH–Fractional Derivatives and Impulses via Coincidence Theory

Fractal and Fractional
The Langevin equation is a model for describing Brownian motion, while the Sturm–Liouville equation is an important mechanical model. This paper focuses on the solvability and stability of nonlinear impulsive Langevin and Sturm–Liouville equations with ...
Kaihong Zhao, Juqing Liu, Xiaojun Lv
doaj   +1 more source

Singular Sturm–Liouville Theory on Manifolds

Journal of Differential Equations, 2001
The authors study the spectral properties of Schrödinger-type operators \(L=-\Delta_g +a(x)\) on a compact Riemannian manifold \((M,g)\), where \(a(x)\) is a real-valued potential defined and continuous, but not necessarily bounded, on \(\widehat M=M-\sigma\), where \(\Sigma\subseteq M\) is a set of measure zero. To be more precise, the paper addresses
Mazzeo, Rafe, McOwen, Robert
openaire   +2 more sources

Internal Wave Characteristics in the Andaman Sea: New Insights From SWOT Observations

Geophysical Research Letters, Volume 53, Issue 10, 28 May 2026.
Abstract High‐resolution, repeat‐pass Sea Surface Height Anomaly (SSHA) observations from the Surface Water and Ocean Topography (SWOT) satellite are used to investigate Internal Solitary Waves (ISW) in the Andaman Sea over a one‐year period starting in July 2023. SWOT captured surface signatures of high‐amplitude ISW, with SSHA exceeding 20 cm.
Anup Kumar Mandal, Aditya Chaudhary, Seemanth M, Ratheesh Ramakrishnan, Neeraj Agarwal, Rashmi Sharma, R. Venkat Shesu, T. V. S Udaya Bhaskar   +7 more
wiley   +1 more source

Indefinite Hamiltonian systems whose Titchmarsh–Weyl coefficients have no finite generalized poles of non-positive type [PDF]

, 2013
The two-dimensional Hamiltonian system (*)  y'(x)=zJH(x)y(x),  x∈(a,b), where the Hamiltonian H takes non-negative 2x2-matrices as values, and $J:= \begin{pmatrix} 0 & -1 \\ 1 & 0 \end{pmatrix}$, has attracted a lot of interest over the past decades ...
Harald Woracek, Matthias Langer, Langer, Matthias, Woracek, Harald   +3 more
core   +1 more source

A metric Sturm–Liouville theory in two dimensions [PDF]

Calculus of Variations and Partial Differential Equations, 2019
A central result of Sturm-Liouville theory (also called the Sturm-Hurwitz Theorem) states that if $ϕ_k$ is a sequence of eigenfunctions of a second order differential operator on the interval $I \subset \mathbb{R}$, then any linear combination satisfies a uniform bound on the roots $$ \# \left\{x \in I:\sum_{k \geq n}{ a_k ϕ_k(x)} = 0 \right\} \geq n-1.
openaire   +3 more sources

Effect of Field Line Torsion on the Polarization of ULF Waves

Journal of Geophysical Research: Space Physics, Volume 131, Issue 5, May 2026.
Abstract In this paper we suggest a simple modification of the dipole magnetic field which introduces field‐aligned currents and torsion to the field lines. The resulting field lines are not contained in the meridional planes and have resemblance to the geomagnetic field lines in the dawn and dusk flanks of the magnetosphere. We analyze polarization of
K. Kabin, A. W. Degeling, R. Rankin
wiley   +1 more source

The spectra of indefinite singular Sturm-Liouville operators [PDF]

, 2021
In der vorliegenden Arbeit werden die spektralen Eigenschaften singulärer Sturm-Liouville- Differentialoperatoren der Form Af=1/r(︁−(pf′)′ + qf)︁ mit reellwertigen Koeffizienten p, q und r untersucht.
Schmitz, Philipp
core   +1 more source

Direct and inverse spectral theory of Sturm-Liouville differential operators [PDF]

, 2009
Diese Arbeit beschäftigt sich mit inverser Spektraltheorie von selbstadjungierten Sturm-Liouville Differentialoperatoren, induziert durch den gewöhnlichen Differentialausdruck zweiter Ordnung $-\frac{d 2}{dx 2}+q(x)$, im Hilbertraum $L 2(a,b)$. Dabei ist
Eckhardt, Jonathan
core  

Maximally dissipative and self‐adjoint extensions of K$K$‐invariant operators

Bulletin of the London Mathematical Society, Volume 58, Issue 5, May 2026.
Abstract We introduce the notion of K$K$‐invariant operators, S$S$, in a Hilbert space, with respect to a bounded and boundedly invertible operator K$K$ defined via K∗SK=S$K^*SK=S$. Conditions such that self‐adjoint and maximally dissipative extensions of K$K$‐invariant symmetric operators are also K$K$‐invariant are investigated.
Christoph Fischbacher, Bart Rosenzweig, Jonathan Stanfill   +2 more
wiley   +1 more source