共振情形下次线性椭圆偏微分方程的解

研究了共振下的微分方程Δｕ＋λ_１ｕ＋ｇ（ｘ，ｕ）＝０，ｘ∈?Ω；ｕ｜_?Ω＝０．在ｇ（ｘ，ｕ）关于ｕ次线性的情形，证明了解的存在性，从而部分地回答了Ｆｉｇｕｅｉｒｅｄｏ ａｎｄ Ｍａｓｓａｂｉ的一个问题．     

投影下的Gronwall不等式

本文对Ｊ．Ｋ．Ｈａｌｅ曾提出的一类广泛的投影下的Ｇｒｏｎｗａｌ不等式问题作了讨论，对满足ｕ（ｔ）≤ａ（ｔ）＋∫_０^tｂ（ｔ－ｓ）ｕ（ｓ）ｄｓ＋∫_０^∞ｃ（ｓ）ｕ（ｔ＋ｓ）ｄｓ，(?)ｔ≥０的函数ｕ（ｔ）∈Ｃ_b⁰（Ｒ₊，Ｒ₊）作了估计．其结果对讨论微分方程的有界解、不变流形及其Ｆｏｌｉａｔｉｏｎ和进一步讨论奇性Ｇｒｏｎｗａｌ不等式都有意义     

关于Buchsbaum环的注记

本文证明了下述结论，设Ａ是一个级数为ｄ的Ｂｕｃｈｓｂａｕｍ环，（ａ₁，ａ₂，…，ａ_n）是Ａ的一个参数系统，则任何正整数ｎ，Ａ／（ａ₁，ａ₂，…，ａ_k）ⁿ（１≤ｋ≤ｄ）仍是ｄ－ｋ维的Ｂｕｃｈｓｂａｕｍ环．     

GAOR迭代法和Jacobi迭代法的敛散关系

本文将文［１］中ＡＯＲ法和Ｊａｃｏｂｉ法同时敛散的结论推广到ＧＡＯＲ法．证明了当Ｊａｃｏｂｉ矩阵Ｂ非负时，解线性方程组Ａｘ＝ｂ（Ａ为不可约矩阵）的ＧＡＯＲ法（０≤γ_ｉ＜ω_ｉ≤１，ｉ＝１，２，…，ｎ）和Ｊａｃｏｂｉ法同时敛散，给出了其谱半径ρ（Ｌ_Ｒ，Ω）和ρ（Ｂ）之间的关系．     

附加广义函数的几个导数

作者证明了广义函数（ｘ±ｉ０）^λｌｎ^k（ｘ±ｉ０）的表示定理,给出了附加广义函数的导数：（ｌｎ^kｘ_±）＇,（ｘ^λ_±ｌｎ^kｘ_±）＇,（ｘ^-n_±ｌｎ^k＇ｘ_±）＇,（ｄ／ｄｘ）｛（ｘ±ｉ０）^λｌｎ^k（ｘ±ｉ０     

一类超临界椭圆方程正解的存在性

本文讨论了球上半线性椭圆Ｄｉｒｉｃｈｌｅｔ问题Δｕ＋λｕ^ｑ＋ｕ^p＝０正解的存在性,其中,λ∈Ｒ,０〈ｑ〈１,ｐ〉ｐ_ｃ≡(Ｎ＋２)/(Ｎ－２)（Ｎ〉２）．在条件Ｎ≤６或Ｎ〉６,ｐ〈ｐ_Ｎ≡（Ｎ＋１－(２Ｎ－３)^1/2）／（Ｎ－３－(２Ｎ－３)^1/2）下,证明了存在唯一的λ₀,λ₀〉０,当λ＝λ₀时,有唯一的径向奇异解及无穷多个正解。     

非正截曲率的完备Riemann流形在无穷远截曲率趋于零的条件

本文给出并证明了定理;设Ｍ为具非正截曲率的完备Ｒｉｅｍａｎｎ流形,Ｔ：［０,＋∞）→Ｍ为Ｍ上的正规测地线,Ｕ是沿Ｔ且初值为零的非平凡正常Ｊａｃｏｂｉ场,若存在ａ＞０,ｔ_０＞０,使得当ｔ≥ｔ_０时．     

非线性奇异扩散方程的第二初边值问题

讨论了非线性奇异扩散方程的第二初边值问题，证明了存在唯一的光滑解，且解关于初值是连续依赖的．同时还简洁地得到解的渐近性质：ｔ^ｌ｜ｕ－ｕ_０｜→０，０＜ｌ＜１/２．     

区间上一类连续自映射的单调迭代根

设Ｉ＝［０,１］,０＜ａ＜ｂ＜１,记Φ_ab≡｛Ｆ∈Ｃ^０（Ｉ）：Ｆ｜［０,ａ］和Ｆ｜［ｂ,１］严格单调递增且Ｆ在［ａ,ｂ］恒取常值｝．本文讨论了Ｆ∈Φ_ab有单调迭代根的充要条件．     

一类拟线性椭圆型偏微分方程的先验界的估计

近几年对边值问题－ｄｉｖ（｜Ｄｕ｜^p-2Ｄｕ）＝λｆ（ｕ）｝在Ω上ｕ｜(?)Ω＝０正解方面已经得到了许多结果．这里λ＞０，Ω是有界区域和对ｓ≥０，ｆ（ｓ）≥０．在本文中在条件Ｎ≥ｐ＞１，Ω＝Ｂ_１＝｛ｘ∈Ｒ^N，｜ｘ｜＜１｝和ｆ∈Ｃ¹（０，∞）∩Ｃ⁰（［０，∞）），ｆ（０）＝０，研究了这类问题的正对称解的先验界估计．     

Navier-Stokes方程与Euler方程的稳定性比较

比较了Navier-Stokes 方程和Euler方程的稳定性;并以它们的典型初值问题为例,分析了Navier-Stokes方程和Euler方程稳定性不同的原因．     

Gauge-invariant description of several (2+1)-dimensional integrable nonlinear evolution equations

We obtain new gauge-invariant forms of two-dimensional integrable systems of nonlinear equations: the Sawada-Kotera and Kaup-Kuperschmidt system, the generalized system of dispersive long waves, and the Nizhnik-Veselov-Novikov system. We show how these forms imply both new and well-known twodimensional integrable nonlinear equations: the Sawada-Kotera equation, Kaup-Kuperschmidt equation, dispersive long-wave system, Nizhnik-Veselov-Novikov equation, and modified Nizhnik-Veselov-Novikov equation. We consider Miura-type transformations between nonlinear equations in different gauges. __________ Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 160, No. 1, pp. 35–48, July, 2009.     

VISCOSITY METHOD OF A NON－HOMOGENEOUS BURGERS EQUATION

Abstract In [1], Ding et al. studied the nonhomogeneous Burgers equation ut uux = μuxx 4x.(1.1) This paper will prove that when μ → 0 the solution of (1.1) will approach the generalized solution of ut uux = 4x.(1.2) The authors notice that the equation (1.2) is beyond the scope of investigations by Oleinik O. in [2]. The solutions here are unbounded in general. The paper also studies the δ-wave phenomenon when (1.2) is jointed with some other equation.     

常系数线性差分方程的微分解法

用微分方法 ,解常系数线性差分方程     

REMARK ON UNIQUE CONTINUATION OF SOLUTIONS TO THE STOKES AND THE NAVIER-STOKES EQUATIONS

1IntroductionUnique continuation of solutions to the linear partial di?erential equations with analyticcoe?cients is well known.There are more general results in elliptic,parabolic and hyperbolicequations(cf.[8-10,12-13]and references therein).The continu…     

New Bounds for the Inhomogenous Burgers and the Kuramoto-Sivashinsky Equations

We give a substantially simplified proof of the near-optimal estimate on the Kuramoto-Sivashinsky equation from a previous paper of the third author, at the same time slightly improving the result. That result relied on two ingredients: a regularity estimate for capillary Burgers and an a novel priori estimate for the inhomogeneous inviscid Burgers equation, which works out that in many ways the conservative transport nonlinearity acts as a coercive term. It is the proof of the second ingredient that we substantially simplify by proving a modified Kármán-Howarth-Monin identity for solutions of the inhomogeneous inviscid Burgers equation. We show that this provides a new interpretation of recent results obtained by Golse and Perthame.     

“Pexiderized” homogeneity almost everywhere

In the paper we examine Pexiderized ?-homogeneity equation almost everywhere. Assume that G and H are groups with zero, (X,G) and (Y,H) are a G- and an H-space, respectively. We prove, under some assumption on (Y,H), that if functions and satisfy Pexiderized ?-homogeneity equation

F₁(αx)=?(α)F₂(x)     

Validity of the KdV equation for the modulation of periodic traveling waves in the NLS equation

Bethuel et al.  and  and Chiron and Rousset [3] gave very nice proofs of the fact that slow modulations in time and space of periodic wave trains of the NLS equation can approximately be described via solutions of the KdV equation associated with the wave train. Here we give a much shorter proof of a slightly weaker result avoiding the very detailed and fine analysis of ,  and . Our error estimates are based on a suitable choice of polar coordinates, a Cauchy–Kowalevskaya-like method, and energy estimates.     

Oscillation and Nonoscillation Criteria for a Second Order Linear Equation

New oscillation and nonoscillation criteria are established for the equation