Local Aronson-Benilan Estimates for Porous Medium Equations under Ricci Flow

In this work we derive local gradient estimates of the Aronson-Benilan type for positive solutions of porous medium equations under Ricci flow with bounded Ricci curvature. As an application, we derive a Harnack type inequality.     

Gradient Estimates for the Porous Medium Equations on Riemannian Manifolds

In this paper we study gradient estimates for the positive solutions of the porous medium equation: $$u_t=\Delta u^m$$ where m>1, which is a nonlinear version of the heat equation. We derive local gradient estimates of the Li–Yau type for positive solutions of porous medium equations on Riemannian manifolds with Ricci curvature bounded from below. As applications, several parabolic Harnack inequalities are obtained. In particular, our results improve the ones of Lu, Ni, Vázquez, and Villani (in J. Math. Pures Appl. 91:1–19, 2009). Moreover, our results recover the ones of Davies (in Cambridge Tracts Math vol. 92, 1989), Hamilton (in Comm. Anal. Geom. 1:113–125, 1993) and Li and Xu (in Adv. Math. 226:4456–4491, 2011).     

Decay Estimates of Solutions to Wave Equations in Conical Sets

We consider the wave equation in an unbounded conical domain, with initial conditions and boundary conditions of Dirichlet or Neumann type. We give a uniform decay estimate of the solution in terms of weighted Sobolev norms of the initial data. The decay rate is the same as in the full space case.     

Periodic Solutions of Porous Medium Equations with Weakly Nonlinear Sources

§ 1.Ｉｎｔｒｏｄｕｃｔｉｏｎ　ＴｈｉｓｐａｐｅｒｉｓｃｏｎｃｅｒｎｅｄｗｉｔｈｔｈｅｔｉｍｅｐｅｒｉｏｄｉｃｓｏｌｕｔｉｏｎｓｏｆｔｈｅｐｏｒｏｕｓｍｅｄｉｕｍｅｑｕａｔｉｏｎｓｗｉｔｈｗｅａｋｌｙｎｏｎｌｉｎｅａｒｓｏｕｒｃｅｓａｎｄｗｉｔｈｔｈｅＤｉｒｉｃｈｌｅｔｂｏｕｎｄａｒｙｖａｌｕｅｃｏｎｄｉｔｉｏｎ ,ｎａｍｅｌｙ ,ｔｈｅｐｒｏｂｌｅｍ ｕ ｔ =Δ(｜ｕ｜ｍ- 1ｕ) +Ｂ(ｘ ,ｔ,ｕ) +ｆ(ｘ ,ｔ)　ｉｎΩ×Ｒ ,(1 .1 )ｕ(ｘ ,ｔ) =0　ｏｎ Ω×Ｒ , (1 .2 )ｕ(ｘ ,ｔ+ω) =ｕ(ｘ ,ｔ)　ｉｎ Ω×Ｒ ,…     

三维广义磁流体方程组解的最优衰减率

本文利用Fourier分解法首次建立了三维广义磁流体动力学方程组弱解的时间衰减估计,得到了该方程解关于时间衰减的上下界估计,并且获得了相应的最优代数衰减率.     

含无穷拉普拉斯算子的渗流问题的李普希兹估计

本文研究含无穷拉普拉斯算子的渗流问题.运用改进的Bernstein方法和光滑逼近,分别建立了该问题严格正粘性解和非负粘性解关于空间变量的李普希兹估计.     

Spatial Decay Estimates for the Solutions to Stokes Equations in Four Kinds of Semi-Infinite Cylinders

This paper investigates the spatial behavior of the solutions of the Stokes equations in a semi-infinite cylinder.We consider four kinds of semi-infinite cylind...     

Gradient Estimates for Solutions of Ultraparabolic Equations

We establish a priori estimates for solutions to ultraparabolic equations which play a crucial role in the solvability of the initial value problem. A class of these equations came from population dynamics, namely from a fish larvae model.      

Decay Estimates for Solutions of Linear Elasticity for Anisotropic Media

We analyse the time decay of solutions to the Cauchy problem for the linear hyperbolic system of elasticity for anisotropic media. As an example, we will consider media with hexagonal symmetry. First we derive decay estimates for special initial data using the method of stationary phase in several variables and degenerate phase function based on the Malgrange preparation theorem. Asymptotic expansions are given to prove the sharpness of the weaker time decay found for zinc and beryl than in the isotropic case. A method using Besov spaces leads to ℒ︁^p–ℒ︁^q-estimates.     

Global Pointwise Decay Estimates for Defocusing Radial Nonlinear Wave Equations

We prove global pointwise decay estimates for a class of defocusing semilinear wave equations in n = 3 dimensions restricted to spherical symmetry. The technique is based on a conformal transformation and a suitable choice of the mapping adjusted to the nonlinearity. As a result we obtain a pointwise bound on the solutions for arbitrarily large Cauchy data, provided the solutions exist globally. The decay rates are identical with those for small data and hence seem to be optimal. A generalization beyond the spherical symmetry is suggested.     

The Decay Rates of Strong Solutions for Navier-Stokes Equations

In this paper, we deduce the estimates on decay rates of higher order derivatives about time variable and space variables for the strong solution to the Cauchy problem of the Navier-Stokes equations. The rate obtained is optimal in the sense that it coincides with that of solution to the heat equation.     

一类非线性抛物方程弱解的L~2 衰减(英文)

本文研究了非线性抛物方程弱解的L2 衰减 ,证明了若u是非线性抛物方程的一个弱解 ,则u满足‖u‖L2 ≤C( 1 t) -n/ 4,其中C是常数且仅依赖于初始值u0 的范数 .     

拟线性椭圆方程的衰减正解

本文建立了一类拟线性椭圆方程具有高度衰减阶正解的存在性，并对此类正解的最大值进行了上下界估计。     

拟线性方程非局部边值问题解的衰减估计

本文讨论一类源于拟静态热弹性力学和控制理论等领域的边值问题,通过构造适当的上下解得到拟线性方程解的衰减估计。     

带粘性线性化BCL方程组的衰减估计

考虑三维空间R3中水波的自由表面的运动,这里研究的方程组首先是由J.L.Bona,T.Colin 和D.Lannes提出的BCL方程组.给出了带粘性的BCL方程组的线性化方程组解的长时间衰减估计,它们将在讨论非线性的带牯性的BCL方程组的整体适定性中起着关键作用.     

Existence and Nonexistence of Global Classical Solutions to Porous Medium and Plasma Equations with Singular Sources

Let Ω be a bounded or unbounded domain in R^n. The initial-boundary value problem for the porous medium and plasma equation with singular terms is considered in this paper. Criteria for the appearance of quenching phenomenon and the existence of global classical solution to the above problem are established. Also, the life span of the quenching solution is estimated or evaluated for some domains.