一类弱耗散Camassa-Holm方程局部强解的适定性及弱解的存在性

使用Pseudoparabolic正则化方法和从弱耗散Camassa-Holm方程自身导出的估计式,在Sobolev空间Hs(R)(s3/2)中,证明了该Camassa-Holm方程解的局部适定性.同时给出了一个在空间Hs(R)(1s2\3)中确保该方程弱解存在的充分条件.     

一类广义层流方程初值问题的整体适定性

讨论了刻画层流问题中比重相近的层间相互作用的数学模型的初值问题.通过引进一类函数空间并证明该初值问题的解在所述空间上的一系列先验估计,得到了该初值问题在初值属于Hs(R)(s≥1)时的整体适定性.     

弱于H1空间的L2-临界非线性Schr(o)dinger方程的柯西问题

讨论Hs(Rn)(n≥1,1-ε＜s＜1)中L2-临界焦聚型非线性Schr(o)dinger方程的柯西问题,这里ε＞0是一个可以表出的很小的数.主要结论给出了在有限时间破裂解的L2集中现象.同时,作为推论,得到了小初值解的整体存在性.     

关于Banach空间中一类奇异积分方程

本文研究Banach空间X上的Volterra型奇异积分方程 这里,算子。在假定A是X上的严格极大增生算子,f∈C~1([0,∞);X),f(0)=0下证明了方程(SI)存在唯一连续解;在附加A为线性,f∈c~∞,f~((k))(0)=0,k≥0,整数等条件下,运用Laplace变换方法得到解的级数表达式。在抽象积分方程理论的研究中,本文首次涉及奇异积分方程解的存在唯一性问题。     

可压Navier-Stokes方程解的最高阶导的最佳衰减估计

该文研究可压Navier-Stokes方程Cauchy问题光滑解的衰减估计问题.假设初始扰动在Hl(R3)(l≥3)中充分小,且属于H1(R3)(0≤s＜5/2),通过对解的高低频分解,结合谱分析和能量估计方法,得到解各阶导数的最佳衰减估计结果.     

一类二阶非齐次微分方程解的增长性与不动点(英文)

本文研究方程f′′+A(z)f′+B(z)f=F解的增长性、解及其导数的不动点问题,其中A(z),B(z)(不恒等于0),F(z)(不恒等于0)是整函数,F的级为无穷.得到方程解的超级、二级不同零点收敛指数、方程解及其一阶和二阶导数的二级不动点收敛指数等的精确估计.     

Banach函数空间的Hlder不等式(英文)

本文给出了基本不等式‖ ∏ni=1aαii ≤‖ ∑ni=1αiai(ai >0 ,αi >0 ,∑ni=1αi =1 )的一个确界形式 ,以此统一得出Banach函数空间Lp(E ,u) ,L∞(E ,u) ,L∞(R) ,C(R)等的H lder函数不等式 .     

Banach函数空间的H(o)lder不等式

本文给出了基本不等式‖nⅡi=1ai,ai≤‖n∑i=1,aiai(ai>0,ai>0,n∑i=1,ai=1)的一个确界形式,以此统一得出Banach函数空间Lp(E,u),L∞(E,u),L∞(R),C(R)等的 H(O)lder函数不等式.     

The local and global existence of solutions for a generalized Camassa-Holm equation

A fully nonlinear generalization of the Camassa-Holm equation is investigated. Using the pseudoparabolic regularization technique, its local well-posedness in Sobolev space Hs(R) with s3/2 is established via a limiting procedure. Provided that the initial momentum (1-x2)u0 satisfies the sign condition, u0∈Hs(R)(s3/2) and u0∈L1(R),the existence and uniqueness of global solutions for the equation are shown to be true in the space C([0,∞); Hs(R))∩C1([0,∞);Hs-1(R)).     

一类拟线性椭圆方程的很弱解的唯一性

利用以极大函数表示的有关Sobolev函数的逐点不等式来构造全局的Lipschitz型检验函数,得到了在一定条件下,拟线性椭圆方程-divA(x, u, Du) = f(x)在grand sobolev空间W0θ,p)(Ω)中的很弱解是唯一的.     

Estimation of the measure of the image of the ball

Under study is the class of ring Q-homeomorphisms with respect to the p-module. We establish a criterion for a function to belong to the class and solve a problem that stems from M. A. Lavrentiev [1] on the estimation of the measure of the image of the ball under these mappings. We also address the asymptotic behavior of these mappings at a point.     

On the distributions of the ratios of the extreme roots to the trace of the Wishart matrix

In this paper, the authors cosider the derivation of the exact distributions of the ratios of the extreme roots to the trace of the Wishart matrix. Also, exact percentage points of these distributions are given and their applications are discussed.     

On the rational approximation of the sum of the reciprocals of the Fermat numbers

Let $\mathcal{G}(z):=\sum_{n\geqslant0} z^{2^{n}}(1-z^{2^{n}})^{-1}$ denote the generating function of the ruler function, and $\mathcal {F}(z):=\sum_{n\geqslant} z^{2^{n}}(1+z^{2^{n}})^{-1}$ ; note that the special value $\mathcal{F}(1/2)$ is the sum of the reciprocals of the Fermat numbers $F_{n}:=2^{2^{n}}+1$ . The functions $\mathcal{F}(z)$ and $\mathcal{G}(z)$ as well as their special values have been studied by Mahler, Golomb, Schwarz, and Duverney; it is known that the numbers $\mathcal {F}(\alpha)$ and $\mathcal{G}(\alpha)$ are transcendental for all algebraic numbers α which satisfy 0<α<1. For a sequence u, denote the Hankel matrix $H_{n}^{p}(\mathbf {u}):=(u({p+i+j-2}))_{1\leqslant i,j\leqslant n}$ . Let α be a real number. The irrationality exponent μ(α) is defined as the supremum of the set of real numbers μ such that the inequality |α?p/q|<q ^?μ has infinitely many solutions (p,q)∈?×?. In this paper, we first prove that the determinants of $H_{n}^{1}(\mathbf {g})$ and $H_{n}^{1}(\mathbf{f})$ are nonzero for every n?1. We then use this result to prove that for b?2 the irrationality exponents $\mu(\mathcal{F}(1/b))$ and $\mu(\mathcal{G}(1/b))$ are equal to 2; in particular, the irrationality exponent of the sum of the reciprocals of the Fermat numbers is 2.     

On the approximation of positive operators and the behaviour of the spectra of the approximants

LetT be a positive linear operator on the Banach latticeE and let (S _n ) be a sequence of bounded linear operators onE which converge strongly toT. Our main results are concerned with the question under which additional assumptions onS _n andT the peripheral spectra (S _n ) ofS _n converge to the peripheral spectrum (T) ofT. We are able to treat even the more general case of discretely convergent sequences of operators.     

Refinement of the asymptotics of the power of the quantile test

One investigates the asymptotic properties of the quantile test, similar to the properties of the Pearson's chi-square test of fit.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 153, pp. 5–15, 1986.The author is grateful to D. M. Chibisov for useful remarks.