On the principle of linearized stability in interpolation spaces for quasilinear evolution equations

Monatshefte für Mathematik - We give a proof for the asymptotic exponential stability in admissible interpolation spaces of equilibrium solutions to quasilinear parabolic evolution equations.     

A class of degenerate diffusion equations with mixed boundary conditions

This paper is concerned with a class of degenerate diffusion equations subject to mixed boundary conditions. Under some structure conditions, we discuss the blow-up property of local solutions and estimate the bounds of “blow-up time.”     

The Cauchy problem for a class of nonlinear degenerate parabolic-hyperbolic equations

Science China Mathematics - In this article, we prove a general existence theorem for a class of nonlinear degenerate parabolichyperbolic equations. Since the regions of parabolicity and...     

Attractors for a class of semi-linear degenerate parabolic equations

We consider degenerate parabolic equations of the form $$\left. \begin{array}{ll}\,\,\, \partial_t u = \Delta_\lambda u + f(u) \\u|_{\partial\Omega} = 0, u|_{t=0} = u_0\end{array}\right.$$ in a bounded domain ${\Omega\subset\mathbb{R}^N}$ , where Δ_λ is a subelliptic operator of the type $$\quad \Delta_\lambda:= \sum_{i=1}^{N} \partial_{x_i}(\lambda_{i}^{2} \partial_{x_i}),\qquad \lambda = (\lambda_1,\ldots, \lambda_N).$$ We prove global existence of solutions and characterize their longtime behavior. In particular, we show the existence and finite fractal dimension of the global attractor of the generated semigroup and the convergence of solutions to an equilibrium solution when time tends to infinity.     

Invariant measure for a class of parabolic degenerate equations

In this paper we consider a stochastic flow in Rⁿ which leaves a closed convex set K invariant. By using a recent characterization of the invariance, involving the distance function, we study the corresponding transition semigroup P_t and its infinitesimal generator N. Due to the invariance property, N is a degenerate elliptic operator. We study existence of an invariant measure ν of P_t and the realization of N in L² (H, ν).     

Energy estimates for a class of degenerate hyperbolic equations

We derive estimates in usual Sobolev norms for solutions of degenerate hyperbolic equations if degenerate coefficients admit only real roots. Loss of derivatives occurs due to the degeneracy.     

Harnack inequality for a class of second-order degenerate elliptic equations

A second-order degenerate elliptic equation in divergence form with a partially Muckenhoupt weight is studied. In a model case, the domain is divided by a hyperplane into two parts, and in each part the weight is a power function of |x| with the exponent less than the dimension of the space in absolute value. It is well known that solutions of such equations are H?lder continuous, whereas the classical Harnack inequality is missing. In this paper, we formulate and prove the Harnack inequality corresponding to the second-order degenerate elliptic equation under consideration.     

On the global bifurcation for a class of degenerate equations

We consider the nonlinear Dirichlet boundary value problems for the second order equation

Infinitely many solutions for a class of degenerate elliptic equations

Let X = (X1, ···, Xm) be an infinitely degenerate system of vector fields. The aim of this paper is to study the existence of infinitely many solutions for the sum of operators X =sum ( ) form j=1 to m Xj Xj.     

A priori estimates for a class of degenerate elliptic equations

In this paper we investigate the regularity of solutions for the following degenerate partial differential equation $$\left \{\begin{array}{ll} -\Delta_p u + u = f \qquad {\rm in} \,\Omega,\\ \frac{\partial u}{\partial \nu} = 0 \qquad \qquad \,\,\,\,\,\,\,\,\,\, {\rm on} \,\partial \Omega, \end{array}\right.$$ when ${f \in L^q(\Omega), p > 2}$ and q ≥ 2. If u is a weak solution in ${W^{1, p}(\Omega)}$ , we obtain estimates for u in the Nikolskii space ${\mathcal{N}^{1+2/r,r}(\Omega)}$ , where r = q(p ? 2) + 2, in terms of the L ^q norm of f. In particular, due to imbedding theorems of Nikolskii spaces into Sobolev spaces, we conclude that ${\|u\|^r_{W^{1 + 2/r - \epsilon, r}(\Omega)} \leq C(\|f\|_{L^q(\Omega)}^q + \| f\|^{r}_{L^q(\Omega)} + \|f\|^{2r/p}_{L^q(\Omega)})}$ for every ${\epsilon > 0}$ sufficiently small. Moreover, we prove that the resolvent operator is continuous and compact in ${W^{1,r}(\Omega)}$ .     

Bifurcation problems for a class of degenerate quasilinear elliptic equations

In this paper we consider the bifurcation problem -div A（x, u）=λa（x）｜u｜^p-2u＋f（x,u,λ） in Ω with p 〉 1.Under some proper assumptions on A（x,ξ）,a（x） and f（x,u,λ）,we show that the existence of an unbounded branch of positive solutions bifurcating Irom the principal eigenvalue of the problem --div A（x, u）=λa（x）｜u｜^p-2u.     

On the strong maximum principle for degenerate parabolic equations

Variants of the strong maximum principle are established for subsolutions to degenerate parabolic equations for which the standard version of the strong maximum principle does not hold. The results are formulated for viscosity solutions.     

The Keldys-Fichera boundary value problem for a class of nonlinear degenerate elliptic equations

This paper discusses the Keldys-Fichera boundary value problem for a kind of degenerate quasilinear elliptic equations in divergence form. The existence theorem, comparison principle and uniqueness theorem are proved. This project supported by NSFC.     

The analyticity of solutions to a class of degenerate elliptic equations

In the present paper, the analyticity of solutions to a class of degenerate elliptic equations is obtained. A kind of weighted norms are introduced and under such norms some degenerate elliptic operators are of weak coerciveness.