Heat content asymptotics with singular initial temperature distributions

We study the heat content asymptotics with either Dirichlet or Robin boundary conditions where the initial temperature exhibits radial blowup near the boundary. We show that there is a complete small-time asymptotic expansion and give explicit geometrical formulas for the first few terms in the expansion.     

On a class of singular boundary value problems with singular perturbation

In this paper we investigate a class of singular second order differential equations with singular perturbation subject to three-point boundary value conditions, whose solution exhibits a couple of boundary layers at two endpoints. We first establish a lower–upper solutions theorem by using the Schauder fixed point theorem. By the asymptotic expansions and the lower–upper solutions theorem we obtain the existence, asymptotic estimates and uniqueness for the proposed problem. Several examples are given for illustrating our results.     

Quenching rates for heat equations with coupled singular nonlinear boundary flux

We study finite time quenching for heat equations coupled via singular nonlinear bound-ary flux. A criterion is proposed to identify the simultaneous and non-simultaneous quenchings. In particular, three kinds of simultaneous quenching rates are obtained for different nonlinear exponent re-gions and appropriate initial data. This extends an original work by Pablo, Quir′os and Rossi for a heat system with coupled inner absorption terms subject to homogeneous Neumann boundary conditions.     

Asymptotic Expansion of Solutions to Singular Perturbation Problems in Critical Cases

This paper investigates the problem of singular perturbed integral initial values and Robin boundary values in the critical case. Based on the boundary layer function method, we not only construct the asymptotic approximation of the original equation, but also prove the uniform validity of the asymptotic solution by successive approximation. At the same time, we give an example to prove the validity of the theoretical results.     

A singular perturbation of the heat equation with memory

In this paper we consider a hyperbolic equation, with a memory term in time, which can be seen as a singular perturbation of the heat equation with memory. The qualitative properties of the solutions of the initial boundary value problems associated with both equations are studied. We propose numerical methods for the hyperbolic and parabolic models and their stability properties are analyzed. Finally, we include numerical experiments illustrating the performance of those methods.     

Keldysh problem for mixed type equation with strong characteristic degeneration and singular coefficient

We study a mixed-type equation of the second kind with a singular coefficient. With the help of the spectral analysis method we establish a uniqueness criterion for a solution of the problem with incomplete boundary data. The solution represents the sum of the Fourier–Bessel series. The substantiation of its uniform convergence is based on an estimate of the separation from zero of the small denominator with the corresponding asymptotic behavior. This allows us to prove the convergence of the series in the class of regular solutions.     

On boundary value problem with singular inhomogeneity concentrated on the boundary

We study the asymptotic behavior of solutions to a boundary value problem for the Poisson equation with a singular right-hand side, singular potential and with alternating type of the boundary condition. Assuming that the boundary microstructure is periodic, we construct the limit problem and prove the homogenization theorem by means of the unfolding method. The proof requires that the dimension be larger than two.     

SINGULAR PERTURBATION OF ROBIN BOUNDARY VALUE PROBLEM FOR THIRD ORDER NONLINEAR SYSTEM WITH BOUNDARY PERTURBATION

ＳＩＮＧＵＬＡＲＰＥＲＴＵＲＢＡＴＩＯＮＯＦＲＯＢＩＮＢＯＵＮＤＡＲＹＶＡＬＵＥＰＲＯＢＬＥＭＦＯＲＴＨＩＲＤＯＲＤＥＲＮＯＮＬＩＮＥＡＲＳＹＳＴＥＭＷＩＴＨＢＯＵＮＤＡＲＹＰＥＲＴＵＲＢＡＴＩＯＮ（黄晓秋）福建师范大学福清分校，邮编：３５０３００Ｈ...     

A singular function boundary integral method for elliptic problems with singularities

In this work we present a singular function boundary integral method for elliptic problems with boundary singularities. In this method, the approximation is constructed from the truncated asymptotic expansion for the solution near the singular point and the Dirichlet boundary conditions are weakly enforced by means of Lagrange multiplier functions. The resulting discrete problem is posed and solved on the boundary of the domain, away from the point of singularity. We are able to show that the method approximates the generalized stress intensity factors, i.e. the coe cients in the asymptotic expansion, at an exponential rate. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

一类催化反应Robin问题的渐近解

研究了一类非线性催化反应微分方程Robin问题.在一定的条件下,先利用摄动方法求出了原Robin问题的外部解,然后用伸长变量和幂级数理论分别构造了解的第一和第二边界层校正项,从而得到了Robin问题解的形式渐近展开式.最后利用微分不等式理论,证明了问题解的渐近表示式的一致有效性.     

Boundary behaviors for Liouville's equation in planar singular domains

We study asymptotic behaviors near the boundary of complete metrics of constant curvature in planar singular domains and establish an optimal estimate of these metrics by the corresponding metrics in tangent cones near isolated singular points on boundary. The conformal structure plays an essential role.     

Incomplete quenching of heat equations with coupled singular logarithms boundary fluxes

This paper deals with quenching phenomena for a heat equations with coupled singular logarithms boundary fluxes. Under appropriate hypotheses, the non-simultaneous quenching of the solution for the system is proved, and the estimates of quenching rates are given. Then we give a natural continuation of the solution (u,v) after the quenching time when the equations occurs non-simultaneous quenching. Moreover, we identify the heat equations verified by the continuation beyond quenching time, i.e., the equations occurs incomplete quenching.     

具有转向点的二阶非线性方程Robin问题的奇摄动(英)

本文应用微分不等式的方法，研究了具有转向点的二阶非线性方程Robin问题的奇摄动，根据fy在转向点附近的性态，边值问题的解将呈现冲击层现象和边界层现象，在适当的假设条件下，我们证明了该问题的存在性和不同的渐近性质。     

一类具有局部弱稳定退化解的奇摄动Robin问题

研究一类一般的二阶非线性方程的奇摄动Robin问题的边界层现象.在退化解是局部弱稳定的主要假设下,利用界定函数法和微分不等式理论证明了呈边界层性态的解的存在性,并给出解的渐近估计.     

On Gevrey solutions of threefold singular nonlinear partial differential equations

We study Gevrey asymptotics of the solutions to a family of threefold singular nonlinear partial differential equations in the complex domain. We deal with both Fuchsian and irregular singularities, and allow the presence of a singular perturbation parameter. By means of the Borel–Laplace summation method, we construct sectorial actual holomorphic solutions which turn out to share a same formal power series as their Gevrey asymptotic expansion in the perturbation parameter. This result rests on the Malgrange–Sibuya theorem, and it requires to prove that the difference between two neighboring solutions is exponentially small, what in this case involves an asymptotic estimate for a particular Dirichlet-like series.     

Reverse bubbling of currents and harmonic heat flows with prescribed singular set

We consider the harmonic heat flow for maps u between B³, the unit ball of , and its boundary S². For a class of possibly singular initial and boundary data we show the existence of a weak solution whose singular set is a fixed discrete set on the vertical axis arbitrarily prescribed. Other examples including isolated singularities moving along a prescribed trajectory are given.Received: 23 October 2002, Accepted: 12 March 2003, Published online: 4 September 2003     

Boundary behaviour for solutions of elliptic singular equations with a gradient term

We investigate the homogeneous Dirichlet boundary value problem for a class of second-order nonlinear elliptic partial differential equations with a gradient term and singular data. Under general conditions on the data, we study the behaviour of the solution near the boundary of the domain. Under suitable additional conditions we also investigate the second-order term in the asymptotic expansion of the solution in terms of the distance from the boundary.     

On singular solutions of the initial boundary value problem for the Stokes system in a power cusp domain

The initial boundary value problem for the non-steady Stokes system is considered in bounded domains with the boundary having a peak-type singularity (power cusp singularity). The case of the boundary value with a nonzero time-dependent flow rate is studied. The formal asymptotic expansion of the solution near the singular point is constructed. This expansion contains both the outer asymptotic expansion and the boundary-layer-in-time corrector with the ‘fast time’ variable depending on the distance to the cusp point. The solution of the problem is constructed as the sum of the asymptotic expansion and the term with finite energy.     

二阶半线性常微分方程Robin边值问题的奇摄动

用基本方法讨论了一个半线性奇摄动Robin边值问题.利用微分不等式理论，证明了问题解的存在性，并得到了解的渐近估计.作为应用，给出了两个例子，一个是将结果应用于一个燃烧反应扩散问题的模型，另一个是得到了有关Dirichlet问题的相应结果.     

Boundary behaviour for solutions of elliptic singular equations with a gradient term

We investigate the homogeneous Dirichlet boundary value problem for a class of second-order nonlinear elliptic partial differential equations with a gradient term and singular data. Under general conditions on the data, we study the behaviour of the solution near the boundary of the domain. Under suitable additional conditions we also investigate the second-order term in the asymptotic expansion of the solution in terms of the distance from the boundary.