Results 61 to 70 of about 1,370 (227)

Dirac lattices, zero-range potentials, and self-adjoint extension [PDF]

Physical Review D, 2015
We consider the electromagnetic field in the presence of polarizable point dipoles. In the corresponding effective Maxwell equation these dipoles are described by three dimensional delta function potentials. We review the approaches handling these: the selfadjoint extension, regularization/renormalisation and the zero range potential methods.
Bordag, M., Munoz-Castaneda, J. M.
openaire   +2 more sources

Isoperimetric inequalities on slabs with applications to cubes and Gaussian slabs

Communications on Pure and Applied Mathematics, Volume 79, Issue 4, Page 1012-1072, April 2026.
Abstract We study isoperimetric inequalities on “slabs”, namely weighted Riemannian manifolds obtained as the product of the uniform measure on a finite length interval with a codimension‐one base. As our two main applications, we consider the case when the base is the flat torus R2/2Z2$\mathbb {R}^2 / 2 \mathbb {Z}^2$ and the standard Gaussian measure
Emanuel Milman
wiley   +1 more source

Hybrid Reaction–Diffusion Epidemic Models: Dynamics and Emergence of Oscillations

Mathematical Methods in the Applied Sciences, Volume 49, Issue 5, Page 4074-4095, 30 March 2026.
ABSTRACT In this paper, we construct a hybrid epidemic mathematical model based on a reaction–diffusion system of the SIR (susceptible‐infected‐recovered) type. This model integrates the impact of random factors on the transmission rate of infectious diseases, represented by a probabilistic process acting at discrete time steps.
Asmae Tajani, Cristiana J. Silva, Guillaume Cantin   +2 more
wiley   +1 more source

Duality for Evolutionary Equations With Applications to Null Controllability

Mathematical Methods in the Applied Sciences, Volume 49, Issue 5, Page 4144-4166, 30 March 2026.
ABSTRACT We study evolutionary equations in exponentially weighted L2$$ {\mathrm{L}}^2 $$‐spaces as introduced by Picard in 2009. First, for a given evolutionary equation, we explicitly describe the ν$$ \nu $$‐adjoint system, which turns out to describe a system backwards in time. We prove well‐posedness for the ν$$ \nu $$‐adjoint system. We then apply
Andreas Buchinger, Christian Seifert
wiley   +1 more source

Reduction of positive self-adjoint extensions

Opuscula Mathematica
Summary: We revise Krein's extension theory of semi-bounded Hermitian operators by reducing the problem to finding all positive and contractive extensions of the ``resolvent operator'' \((I+T)^{-1}\) of \(T\). Our treatment is somewhat simpler and more natural than Krein's original method which was based on the Krein transform \((I-T)(I+T)^{-1 ...
Zsigmond Tarcsay, Zolt�n Sebesty�n
openaire   +2 more sources

Mesh and Model Adaptivity for Multiscale Elastoplastic Models With Prandtl‐Reuss Type Material Laws

International Journal for Numerical Methods in Engineering, Volume 127, Issue 6, 30 March 2026.
ABSTRACT Homogenization methods simulate heterogeneous materials like composites effectively, but high computational demands can offset their benefits. This work balances accuracy and efficiency by assessing model and discretization errors of the finite element method (FEM) through an adaptive numerical scheme.
Arnold Tchomgue Simeu, Ismail Caylak, Richard Ostwald   +2 more
wiley   +1 more source

Operators on anti-dual pairs: self-adjoint extensions and the Strong Parrott Theorem [PDF]

, 2020
Zsigmond Tarcsay, Tamás Titkos
openalex   +2 more sources

Robust Control Design and Analysis Based on Lifting Linearization of Nonlinear Systems Under Uncertain Initial Conditions

International Journal of Robust and Nonlinear Control, Volume 36, Issue 5, Page 3047-3067, 25 March 2026.
ABSTRACT This paper presents a robust control synthesis and analysis framework for nonlinear systems with uncertain initial conditions. First, a deep learning‐based lifting approach is proposed to approximate nonlinear dynamical systems with linear parameter‐varying (LPV) state‐space models in higher‐dimensional spaces while simultaneously ...
Sourav Sinha, Mazen Farhood
wiley   +1 more source

Attribute Implication Bases From Galois Connection Structures

Mathematical Methods in the Applied Sciences, Volume 49, Issue 4, Page 2729-2753, 15 March 2026.
ABSTRACT Modeling knowledge systems by determining relationships among key variables have been and currently is a fundamental and nontrivial challenge in real‐world scenarios. Many approaches have been developed to reach this goal, but many of them are heuristic and require of alternative procedures to provide robust and tractable rules.
M. Eugenia Cornejo, Jesús Medina, Francisco José Ocaña   +2 more
wiley   +1 more source

Self-adjoint Extensions of Schrödinger Operators with ?-magnetic Fields on Riemannian Manifolds

Acta Polytechnica, 2010
We consider the magnetic Schr¨odinger operator on a Riemannian manifold M. We assume the magnetic field is given by the sum of a regular field and the Dirac δ measures supported on a discrete set Γ in M.
T. Mine
doaj