四阶椭圆方程基态解的集中性态

该文分析了四阶椭圆方程△^２u=|x|^au^p-1,x∈Ω; u=\Delta u=0 , x ∈аΩ, (Ω表示Rⁿ中以原点为中心的球)基态解的集中性态,并证明了当p趋近于 2^*=\frac{2n}{n-4} (n>4)时基态解u_p集中在Ω的边界附近.     

Hartman线性化定理的改进

Hartman线性化定理即: 如果方阵A的特征根实部异于零, f(x)有界且有小Lipschitz常数, 则存在Rⁿ的同胚将非线性系x = Ax + f (x)的解映为线性系x'' = Ax的解. 在允许非线性项f(x)的部分分量无界, 同时不增加任何条件和无任何特殊限制的情形下, 获得了全局拓扑线性化的结论, 从而使Hartman线性化定理得到了实质性的改进.     

一类非线性多重调和方程△mu=f(|x|,u,|▽u|)的正整解

本文建立了一类Rⁿ(n≥3)中非线性多重调和方程△^mu=f(|x|,u,|▽u|)(m≥2)正的径向对称整体解的存在性定理,并给出了解的有关性质,推广了文[1]-[4]的有关结果.     

积域上奇异积分算子的Lp有界性

用旋转法证明了对于Ω∈ L(log⁺L)² (Sⁿ-1×S^m-1),Ω(x′,y′)dσ(x′)= 0(y′∈S^m-1), Ω(x′,y′)dσy′)=0(x′∈Sⁿ-1),带核函数K(u,v)= Ω(u′,v′)|u|^-n|v|^-m的奇异积分算子T是L^p(Rⁿ×R^m)有界的,其中1<p<∞.     

带强迫项的二阶非线性椭圆方程的区域振动准则

对二阶非线性椭圆型方程∑ _i,j=1ⁿ D_i[A_ij(x)D_jy]+∑_i=1ⁿ b_i(x)D_iy+q(x)f(y)=e(x)建立了若干新的振动准则, 所得结果仅依赖于方程在外区域Ω С Rⁿ的一个子区域序列的信息而有别于已知的大多数结论.     

Calderón-Zygmund分解的一种形式及其在算子内插中的应用

本文应用原子H~p(R~n)理论得到Calderón-Zygmund分解的一种形式,即对f(x)∈L^p(Rⁿ),p>1,及对任意00,有f(x)=g(x)+b(x),其中 应用这一结果给出了Fefferman和Stein关于H''(Rⁿ)和L^p(Rⁿ)之间算子内插定理及Coifman和Weiss关于H^p1(Rⁿ)和L^p2(Rⁿ)之间算子内插定理的简化证明,并推广了Strampacchia关于之间算子内插定理.     

H1中(次)临界的复Ginzburg-Landau

研究H¹ (Rⁿ)中临界的复Ginzburg-Landau方程的初值问题, 当空间维数n≥3时, 讨论了它的解在空间C(0, ∞; 1(Rⁿ) )∩L²(0, ∞;H ^{1, 2n/(n-2)} (Rⁿ) )的长时间衰减行为. 当空间维数n≥1时, 对非线性项在H¹(Rⁿ)中具有次临界的增长阶的情形也有类似的结果.     

拟共形映射的一个充要条件

设f:R^n_→ Rⁿ是一同胚,该文证明了 f 是拟共形映射的充要条件是 f 将 Rⁿ 中的任一John域映成 Rⁿ 中的John域.     

Marcinkiewicz积分及其交换子在H1(<SPAN style=

建立了Marcinkiewicz积分从Hardy空间H¹(Rⁿ´R^m)到Lebesgue空间L¹(Rⁿ´R^m)的有界性, 以及它们与Lipschitz函数所生成的交换子从Hardy空间L^Mq(Rⁿ´R^m)到Lebesgue空间H¹(Rⁿ´R^m)的有界性, 其中q>1.     

与强奇异 Calderón-Zygmund 算子相关的Toeplitz型算子

研究与强奇异Calderón-Zygmund 算子和Lipschitz函数b∈Λ^&#8729;_β0（Rⁿ）相关的Toeplitz型算子T_b(f)从 L^p（Rⁿ）到L^q（Rⁿ） 的有界性和 L^p（Rⁿ）到F^&#8729;β₀,∞ _p的有界性,1/q=1/p-β₀/n. 得到了广义Toeplitz型算子Θ^b_α0 是 L^p（Rⁿ）到L^q（Rⁿ）有界的,1/q=1/p-(α₀+β₀)/n.上述结果包含了相应的交换子的有界性.同时还得到了与强奇异Calderón-Zygmund 算子和BMO函数b相关的 Toeplitz型算子 T_b(f)的L^p（Rⁿ）有界性, 1ápá∞ .     

双调和方程特征值问题

该文讨论Navier边值条件下的双调和特征值问题 Δ²u=λa(x)u+f(x, u), x∈ Ω, u=Δu=0, x∈ Ω, 解的存在性, 其中Ω R^N(N ≥ 5)是有界光滑区域, Δ²为双调和算子, 权函数a(x)> 0 a. e. 于Ω, 且 a(x)∈L^r(Ω) (r ≥ N/4). 应用变分方法, 得出了在f(x, u)=0的情况下方程的第二特征值, 并研究了它的结构. 同时在f(x, u) 满足一定的条件下, 得出了共振与非共振情形下方程非零解的存在性 .     

The Baire Method for the Prescribed Singular Values Problem

The paper investigates the vectorial Dirichlet problem definedby S_j( u(x))=1,xnO; a.e., j=1,...,n, u(x)=\(x),\,x\in|O. end{cases}Here O is an open bounded subset of Rⁿ with boundary |O, and_j(A) (j=1,...,n) denote the singular values of the gradient u(x). The existence of solutions is established under one ofthe following assumptions: : O – Rⁿ is continuous on Oand locally contractive on O, or : |O – Rⁿ is contractiveon |O. This extends a result due to Dacorogna and Marcellini.The approach is based on the Baire category method developedearlier by the authors.     

A symmetry-breaking problem in the annulus

We study questions of degeneracy and bifurcation for radial solutions of the semilinear elliptic equation ?u(x) + f(u(x)) = 0, x isin; [math001], [math001]an annulus in Rⁿ, with homogeneous Dirichlet boundary conditions. For certain nonlinearities f(u), we prove existence of degenerate radial solutions u (for which the kernel of the linearized operator Lz = ?z + [math001](u)z, z isin; C²We study questions of degeneracy and bifurcation for radial solutions of the semilinear elliptic equation ?u(x) + f(u(x)) = 0, x isin; [math001], [math001]an annulus in Rⁿ, with homogeneous Dirichlet boundary conditions. For certain nonlinearities f(u), we prove existence of degenerate radial solutions u (for which the kernel of the linearized operator Lz = ?z + [math001](u)z, z isin; C²$⁰([math001]), is non-trivial) and existence of nonradial solutions for the semi-linear equation. These nonradial (asymmetric) solutions are obtained via a bifurcation procedure from the radial (symmetric) ones. This phenomena is called symmetry-breaking. The bifurcation results are proved by a Conley index argument     

带权的 p-Laplacian 非线性特征值问题解的存在性

文利用变分方法讨论了方程-△p^u=λ a(x)(u^{+})^q-1-μ a(x)(u^-)^q-1+f(x,u), u∈W₀^1,p(Ω), 当 p≠q时的可解性. 其中Ω是 R^N(N≥ 3)中的有界光滑区域,权重函数a(x)∈ L^r(Ω), (r≥Np/Np-Nq+pq)且a(x)>0, a.e.于Ω, f满足某些条件.     

一类带权函数的拟线性椭圆方程

该文利用变分方法讨论了方程 -△_p u=λa(x)(u⁺)^p-1-μa(x)(u^-)^p-1+f(x, u), u∈W₀^1,p(\Omega)在(λ, μ)\not\in ∑_p和(λ, μ) ∈ ∑_p 两种情况下的可解性, 其中\Omega是 R^N(N≥3)中的有界光滑区域, ∑_p为方程 -△_p u=α a(x)(u⁺)^p-1-βa(x)(u^-)^p-1, u∈ W₀^1,p(\Omega)的Fucik谱, 权重函数a(x)∈ L^r(\Omega) (r≥ N/p)$且a(x)>0 a.e.于\Omega, f满足一定的条件.     

非线性抛物椭圆方程组的正则解和奇异解

该文用单模方法在Lorentz空间研究了抛物椭圆方程组奇异解和正则解的存在性, 其中初值属于Lorentz空间L^{n/2,∞ ₍}Rⁿ), n≥ 3. 利用时间加权的Lorentz空间, 还得到了其正则解. 此外, 如果初值满足自相似结构, 也得到了自相似解的存在性.     

Singularly perturbed Neumann problem for fractional Schrdinger equations

This paper is concerned with a Neumann type problem for singularly perturbed fractional nonlinear Schrdinger equations with subcritical exponent. For some smooth bounded domain ?  R~n, our boundary condition is given by∫_?u(x)-u(y)/|x-y|~(n+2s)dy = 0 for x ∈ R~n\?.We establish existence of non-negative small energy solutions, and also investigate the integrability of the solutions on Rn.     

Asymptotic Behavior of Solutions of Differential Equations with Variable Delays

The authors consider the system of forced differential equationswith variable delays whereB_j(t) is a continuous n x n matrix on R⁺, F C(R⁺, Rⁿ) and C(R⁺, R⁺). Using Razumikhin-type techniques and Liapunov'sdirect method, they establish conditions to ensure the ultimateboundedness and the global attractivity of solutions of (*),and when F(t) = 0, the asymptotic stability of the zero solution.Under those same conditions, they also show that is a necessary and sufficient condition for allof the above properties to hold. 1991 Mathematics Subject Classification:34K15, 34C10.     

Error estimates for the approximate solutions of a nonlinear hyperbolic equation given by finite volume schemes

This paper is devoted to the study of an error estimate of thefinite volume, approximation to the solution u L(R_N x R) ofthe equation u_t + div(Vf(u)) = 0, where v is a vector functiondepending on time and space. A 'h' error estimate for an initialvalue in BV(R^N) is shown for a large variety of finite volumemonotonous flux schemes, with an explicit or implicit time discretization.For this purpose, the error estimate is given for the generalsetting of approximate entropy solutions, where the error isexpressed in terms of measures in R^N and R^N x R. The study ofthe implicit schemes involves the study of the existence anduniqueness of the approximate solution. The cases where an 'h'error estimate can be achieved are also discussed.