Singularly perturbed elliptic systems

We study the existence and concentration behavior of positive solutions for a class of Hamiltonian systems (two coupled nonlinear stationary Schrödinger equations). Combining the Legendre–Fenchel transformation with mountain pass theorem, we prove the existence of a family of positive solutions concentrating at a point in the limit, where related functionals realize their minimum energy. In some cases, the location of the concentration point is given explicitly in terms of the potential functions of the stationary Schrödinger equations.     

Singularly perturbed partially dissipative systems of equations

Theoretical and Mathematical Physics - We construct an asymptotic expansion in a small parameter of a boundary layer solution of the boundary value problem for a system of two ordinary differential...     

SINGULARLY PERTURBED NONLINEARELLIPTIC SYSTEMS IN STRIP DOMAIN

Singularly perturbed problems for the nonlinear dliptie systems in a strip domain are considered. Under suitabla conditions, by using the comparison theorem, the existence andasymptotic behavior of solution for the boundary value problems are studied.     

Weighted singularly perturbed hybrid stochastic systems

In this paper weighted singularly perturbed hybrid stochastic systems are discussed. Under some reasonable assumptions, it is shown that there exists a uniformly δ-optimal policy when the perturbation is sufficiently small.Received: December 2005 / Revised: March 2005This author was supported partially by National Natural Science Foundation of China under grant 60274050, 70221001 and 70328001.This author was supported partially by Australia Research Council Grant #A49532206.     

Singularly perturbed normal operators

We present a generalization of the definition of singularly perturbed operators to the case of normal operators. To do this, we use the idea of normal extensions of a prenormal operator and prove the relation for resolvents of normal extensions similar to the M. Krein relation for resolvents of self-adjoint extensions. In addition, we establish a one-to-one correspondence between the set of singular perturbations of rank one and the set of singularly perturbed (of rank one) operators. Kiev Polytechnic Institute, Kiev. Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 51, No. 8, pp. 1045–1053, August, 1999.     

Singularly perturbed functional-differential inclusions

Differential inclusions of a retarded type with a small real parameter >0 in part of the derivatives are considered. We prove upper semicontinuity of the map set of solutions at =0⁺ inC[0, 1]×(L ²(0, 1)–weak) topology. In case of constant delay lower semicontinuity inC[0, 1]×(L ¹(0, 1)–strong) is shown.     

Singularly perturbed pseudoparabolic equation

An asymptotic expansion of the contrasting structure‐like solution of the generalized Kolmogorov–Petrovskii–Piskunov equation is presented. A generalized maximum principle for the pseudoparabolic equations is developed. This, together with the generalized differential inequalities method, allows to prove the consistence and convergence of the asymptotic series method. Copyright © 2016 John Wiley & Sons, Ltd.     

Singularly perturbed integral equations

We study singularly perturbed Fredholm equations of the second kind. We give sufficient conditions for existence and uniqueness of solutions and describe the asymptotic behavior of the solutions. We examine the relationship between the solutions of the perturbed and unperturbed equations, exhibiting the degeneration of the boundary layer to delta functions. The results are applied to several examples including the Volterra equations.     

Controllability of perturbed nonlinear stochastic integrodifferential systems

The purpose of this paper is to establish the sufficient conditions concerning the complete controllability of stochastic integrodifferential systems in finite dimensional spaces by using the Banach fixed point theorem. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Singularly perturbed elliptic systems and multi-valued harmonic functions with free boundaries

Here we study the asymptotic limits of solutions of some singularly perturbed elliptic systems. The limiting problems involve multiple valued harmonic functions or, in general, harmonic maps to singular spaces and free interfaces between supports of various components of the maps. The main results of the paper are the uniform Lipschitz regularity of solutions as well as the regularity of free interfaces.

     

Singularly perturbed boundary value problems

1.IntroductionThesingularlypedurbednonlineartwO-pointboundaryvalueproblemsinthisarticleareofthefollowingtypewhereconstantparametere>0,constantsx?ER,asERe.Thestatesofthesystem(XI(t),Xz(t),YI(t),YZ(t)),whichtakevaluesinRxRexRadxRe,containonepart(XI(t),YI(t))calledslowvariablesandonepart(XZ(t),YZ(t))calledfastvariables.Welookforthesolutions(XI,X2,YI,Y2)EL'(0,T;R m m)whichsatisfysystem(1).Suchasituationiscommonintheapplications.Itappearsforexampleineconomicmodelstotakeintoaccoun…     

Singularly perturbed finite element methods

Summary This paper introduces a new piecewise linear finite element, which is designed to handle singularly perturbed ordinary differential equations. Both pointwise and global estimates (which are independent of the perturbation parameter) are obtained.     

Singularly perturbed homotopy analysis method

In this paper we combined the homotopy analysis method (HAM) and the method of integral manifold (MIM) to investigate the problem of thermal explosion in two-phases polydisperse combustible mixtures of gas with fuel droplets. The size distribution of the fuel droplets is assumed to be continuous in the form of an exponential distribution and is found from the solution of the kinetic equation for the probability density function. The system of the polydisperse fuel spray takes into account the effects of the thermal radiation and convection. By applying the HAM and the MIM, we derived an analytical solution of the system and we compared our results with the numerical solutions.     

Stability of singularly perturbed nonlinear stochastic hybrid systems

The problem of exponential mean-square stability of nonlinear singularly perturbed, stochastic hybrid systems is studied in this article. Two groups of nonlinear systems are considered separately. To obtain the sufficient conditions of stability, two basic approaches of stability analysis for hybrid systems with a given Markovian switching rule and any Markovian switching rule and singularly perturbed non–hybrid systems were combined. The Lyapunov techniques were used in both approaches. The obtained results are illustrated by examples.     

Singularly perturbed and nonlocal modulation equations for systems with interacting instability mechanisms

Summary Two related systems of coupled modulation equations are studied and compared in this paper. The modulation equations are derived for a certain class of basic systems which are subject to two distinct, interacting, destabilising mechanisms. We assume that, near criticality, the ratio of the widths of the unstable wavenumber-intervals of the two (weakly) unstable modes is small—as, for instance, can be the case in double-layer convection. Based on these assumptions we first derive a singularly perturbed modulation equation and then a modulation equation with a nonlocal term. The reduction of the singularly perturbed system to the nonlocal system can be interpreted as a limit in which the width of the smallest unstable interval vanishes. We study and compare the behaviour of the stationary solutions of both systems. It is found that spatially periodic stationary solutions of the nonlocal system exist under the same conditions as spatially periodic stationary solutions of the singularly perturbed system. Moreover, these solutions can be interpreted as representing the same quasi-periodic patterns in the underlying basic system. Thus, the ‘Landau reduction’ to the nonlocal system has no significant influence on the stationary quasi-periodic patterns. However, a large variety of intricate heteroclinic and homoclinic connections is found for the singularly perturbed system. These orbits all correspond to so-called ‘localised structures’ in the underlying system: They connect simple periodic patterns atx → ± ∞. None of these patterns can be described by the nonlocal system. So, one may conclude that the reduction to the nonlocal system destroys a rich and important set of patterns.     

Singularly perturbed problems with double singularity

A class of singularly perturbed initial and boundary value problems for systems of linear differential equations with singularities of various types is studied. The asymptotics of the solutions of these problems is constructed; in contrast to known results, it involves boundary layers of new types that are dependent not only on the spectrum of the limit operator. Translated fromMatematicheskie Zametki, Vol. 62, No. 4, pp. 494–501, October, 1997. Translated by N. K. Kulman     

Singularly perturbed elliptic boundary value problems

Summary The paper treats elliptic operators of the form L(ɛ∂₁, ..., ɛ∂_n), where L is a polynomial in a variables of order 2m₁, and ɛ is a small parameter. Solutionsu _ɛ of Lu=0 in a half space satisfyng conditions B_j(ɛ∂₁, ɛ∂₂, ..., ɛ∂_n)u=ɛγ_jϕ_j(x)(j=1, ..., m₁) on the boundary are constructed and estimated using H?lder norms, Poisson kernels, and an elaborate potential theory. Properties of the interior limit u₀=u _ɛ(κ) are studied. The paper is preparatory to a detailed investigation of Schauder estimates for such problems with variables coefficients. Supported in part by N. S. F. Grant GP-11660. Entrata in Redazione il 9 gennaio 1971.     

Singularly perturbed evolution equations in Banach spaces

The singular perturbation method is applied to systems of linear evolution equations in Banach spaces with one of the time derivatives multiplied by a small parameter. An asymptotic solution of any given order is shown to consist of inner and outer terms obtained by a proper choice of initial conditions, and to converge uniformly to the exact solution.