Results 21 to 30 of about 133,517 (285)

Perturbation Theory for Metastable States of the Dirac Equation with Quadratic Vector Interaction [PDF]

, 2009
The spectral problem of the Dirac equation in an external quadratic vector potential is considered using the methods of the perturbation theory. The problem is singular and the perturbation series is asymptotic, so that the methods for dealing with ...
A. Sidi, B. Simon, B. Thaller, E. C. Titchmarsh, E. J. Beltrami, G. 't Hooft, G. H. Hardy, M. Reed, Riccardo Giachetti, T. Kato, V. Berestetski, Vincenzo Grecchi   +11 more
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PERTURBING SINGULAR SOLUTIONS OF THE GELFAND PROBLEM [PDF]

Communications in Contemporary Mathematics, 2007
The equation -Δu = λeuposed in the unit ball B ⊆ ℝN, with homogeneous Dirichlet condition u|∂B= 0, has the singular solution [Formula: see text] when λ = 2(N - 2). If N ≥ 4 we show that under small deformations of the ball there is a singular solution (u,λ) close to (U,2(N - 2)).
Davila, J., Dupaigne, L.
openaire   +4 more sources

A Posteriori Error Estimates for Hughes Stabilized SUPG Technique and Adaptive Refinement for a Convection-Diffusion Problem

Advances in Mathematical Physics, 2020
The motive of the present work is to propose an adaptive numerical technique for singularly perturbed convection-diffusion problem in two dimensions. It has been observed that for small singular perturbation parameter, the problem under consideration ...
Brehmit Kaur, Vivek Sangwan
doaj   +1 more source

Multiple perturbations of a singular eigenvalue problem

, 2015
We study the perturbation by a critical term and a $(p-1)$-superlinear subcritical nonlinearity of a quasilinear elliptic equation containing a singular potential. By means of variational arguments and a version of the concentration-compactness principle
Cencelj, Matija, Repovš, Dušan, Virk, Žiga   +2 more
core   +1 more source

A Singular Tempered Sub-Diffusion Fractional Equation with Changing-Sign Perturbation

Axioms
In this paper, we establish some new results on the existence of positive solutions for a singular tempered sub-diffusion fractional equation involving a changing-sign perturbation and a lower-order sub-diffusion term of the unknown function.
Xinguang Zhang, Jingsong Chen, Lishuang Li, Yonghong Wu   +3 more
doaj   +1 more source

Positive Solutions for a Weakly Singular Hadamard-Type Fractional Differential Equation with Changing-Sign Nonlinearity

Journal of Function Spaces, 2020
In this paper, we focus on the existence of positive solutions for a class of weakly singular Hadamard-type fractional mixed periodic boundary value problems with a changing-sign singular perturbation.
Xinguang Zhang, Lixin Yu, Jiqiang Jiang, Yonghong Wu, Yujun Cui   +4 more
doaj   +1 more source

Singular Perturbation Problem in Boundary/Fractional Combustion

, 2015
Motivated by a nonlocal free boundary problem, we study uniform properties of solutions to a singular perturbation problem for a boundary-reaction-diffusion equation, where the reaction term is of combustion type.
Petrosyan, Arshak, Shi, Wenhui, Sire, Yannick   +2 more
core   +3 more sources

Multiplicity of Positive Solutions for a Singular Tempered Fractional Initial-Boundary Value Problem with Changing-Sign Perturbation Term

Fractal and Fractional
In this paper, we focus on the multiplicity of positive solutions for a singular tempered fractional initial-boundary value problem with a p-Laplacian operator and a changing-sign perturbation term.
Xinguang Zhang, Peng Chen, Lishuang Li, Yonghong Wu   +3 more
doaj   +1 more source

Random Homogenization in a Domain with Light Concentrated Masses

Mathematics, 2020
In the paper, we consider an elliptic problem in a domain with singular stochastic perturbation of the density located near the boundary, depending on a small parameter.
Gregory A. Chechkin, Tatiana P. Chechkina   +1 more
doaj   +1 more source

Singular perturbations and scaling

, 2018
Scaling transformations involving a small parameter ({\em degenerate scalings}) are frequently used for ordinary differential equations that model (bio-) chemical reaction networks.
Lax, Christian, Walcher, Sebastian
core   +1 more source