Results 91 to 100 of about 103,519 (218)

Application of Group‐Theoretical Approaches in Structural Natural Frequency Analyses

International Journal for Numerical Methods in Engineering, Volume 127, Issue 7, 15 April 2026.
ABSTRACT Group theory has profoundly advanced physics and chemistry in systems with symmetries. Yet its use in structural engineering applications has not yet been fully explored beyond the aesthetics of symmetric designs. This work addresses two significant gaps that have limited the broader adoption of group‐theoretic methods in structural vibration ...
Shiyao Sun, Kapil Khandelwal
wiley   +1 more source

Singular Potentials in Quantum Mechanics and Ambiguity in the Self-Adjoint Hamiltonian

Symmetry, Integrability and Geometry: Methods and Applications, 2007
For a class of singular potentials, including the Coulomb potential (in three and less dimensions) and $V(x) = g/x^2$ with the coefficient $g$ in a certain range ($x$ being a space coordinate in one or more dimensions), the corresponding Schrödinger ...
Tamás Fülöp
doaj  

On a new formula relating localisation operators to time operators [PDF]

, 2009
We consider in a Hilbert space a self-adjoint operator H and a family Phi=(Phi_1,...,Phi_d) of mutually commuting self-adjoint operators. Under some regularity properties of H with respect to Phi, we propose two new formulae for a time operator for H and
de Aldecoa, Rafael Tiedra, Richard, Serge   +1 more
core   +2 more sources

Green's Function and Convergence of Fourier Series for Elliptic Differential Operators with Potential from Kato Space

Abstract and Applied Analysis, 2010
We consider the Friedrichs self-adjoint extension for a differential operator A of the form A=A0+q(x)⋅, which is defined on a bounded domain Ω⊂ℝn, n≥1 (for n=1 we assume that Ω=(a,b) is a finite interval). Here A0=A0(x,D) is a formally self-adjoint and a
Valery Serov
doaj   +1 more source

Some Applications of the Spectral Theory for the Integral Transform Involving the Spectral Representation

Journal of Function Spaces and Applications, 2012
In many previous papers, an integral transform ℱγ,β was just considered as a transform on appropriate function spaces. In this paper we deal with the integral transform as an operator on a function space.
Hyun Soo Chung, Seung Jun Chang
doaj   +1 more source

Formally self-adjoint quasi-differential operators and boundary-value problems

Electronic Journal of Differential Equations, 2013
We develop the machinery of boundary triplets for one-dimensional operators generated by formally self-adjoint quasi-differential expression of arbitrary order on a finite interval.
Andrii Goriunov, Vladimir Mikhailets, Konstantin Pankrashkin   +2 more
doaj  

Fractional Sturm-Liouville operators on compact star graphs

Demonstratio Mathematica
In this article, we examine two problems: a fractional Sturm-Liouville boundary value problem on a compact star graph and a fractional Sturm-Liouville transmission problem on a compact metric graph, where the orders αi{\alpha }_{i} of the fractional ...
Mutlu Gökhan, Uğurlu Ekin
doaj   +1 more source

Generalised Dirac-Schrödinger operators and the Callias Theorem

Forum of Mathematics, Sigma
We consider generalised Dirac-Schrödinger operators, consisting of a self-adjoint elliptic first-order differential operator $\mathcal {D}$ with a skew-adjoint ‘potential’ given by a (suitable) family of unbounded operators.
Koen van den Dungen
doaj   +1 more source

Diagonals of self-adjoint operators I: Compact operators

Journal of Functional Analysis
Given a self-adjoint operator $T$ on a separable infinite-dimensional Hilbert space we study the problem of characterizing the set $\mathcal D(T)$ of all possible diagonals of $T$. For compact operators $T$, we give a complete characterization of diagonals modulo the kernel of $T$.
Marcin Bownik, John Jasper
openaire   +2 more sources

The Legendre equation and its self-adjoint operators

Electronic Journal of Differential Equations, 2011
The Legendre equation has interior singularities at -1 and +1. The celebrated classical Legendre polynomials are the eigenfunctions of a particular self-adjoint operator in $L^2(-1,1)$. We characterize all self-adjoint Legendre operators in $L^2(-1,1)$
Lance L. Littlejohn, Anton Zettl
doaj