Operator Matrices as Generators of Cosine Operator Functions

We introduce an abstract setting that allows to discuss wave equations with time-dependent boundary conditions by means of operator matrices. We show that such problems are well-posed if and only if certain perturbations of the same problems with homogeneous, time-independent boundary conditions are well-posed. As applications we discuss two wave equations in L^p(0, 1) and in L²(Ω) equipped with dynamical and acoustic-like boundary conditions, respectively.     

关于余弦算子函数的一个结果

设Ａ是Ｂａｎａｃｈ空间Ｘ中的闭线性算子,对凡　是单射。文中定义了Ｂａｎａｃｈ空间　范数　强于Ｘ的范数。我们证明了算子Ａ在空间Ｚ中的部分ＡＺ生成Ｚ中的一个余弦算子函数,空间Ｚ具有某种意义上的极大性。     

正则余弦算子函数的内插和外插定理

该文研究正则余弦算子函数的内插和外插．证明了线性算子A在Banach空间X中生成一个指数有界的C-正则余弦函数当且仅当存在Banach空间Y和线性算子B使得：［R这里是C在Y中的有界扩张，B在Y中生成一个强连续余弦算子函数且A＝B|x．     

正则Cosine算子函数的乘积扰动定理

本文研究了正则cosine算子函数的乘积扰动性,在正则化算子C的值域不 一定稠密的一般情形下,获得了若干正则cosine算子函数的乘积扰动定理.     

On Dual Cosine Operator Function

Some basic properties of daul cosine operator function are given. The concept and characterization of θ-reflexivity with respect to cosine operator function are first studied.     

Kakeya极大算子及其分数次情形的正则性

研究中心Kakeya(Nikodym)极大算子K_N(N2)及其分数次情形K_(α,N)(0αd)的正则性.特别地,建立了中心分数次Kakeya极大算子K_(α,N)是从W~(1,p)(R~d)到W~(1,q)(R~d)上的有界连续算子,其中1p∞,q=dp/(d-αp)和0≤αd/p.还证明了中心Kakeya极大算子K_N是分数次Sobolev空间W~(s,p)(R~d),非齐次Triebel-Lizorkin空间F_s~(p,q)(R~d)以及非齐次Besov空间B_s~(p,q)(R~d)上的有界连续算子,其中0s1,1p,q∞.此外,也考虑分数次Kakeya极大函数的弱导数的两种点态估计以及其离散情形的正则性.     

On Local Integrated Cosine Functions

§ 1.Ｉｎｔｒｏｄｕｃｔｉｏｎ　Ｔｈｒｏｕｇｈｏｕｔｔｈｉｓｐａｐｅｒ,ＸｉｓａＢａｎａｃｈｓｐａｃｅ,ｅｑｕｉｐｐｅｄｗｉｔｈａｎｏｒｍ· ,Ｂ(Ｘ)ｓｔａｎｄｓｆｏｒｔｈｅＢａｎａｃｈａｌｇｅｂｒａｏｆａｌｌｂｏｕｎｄｅｄｌｉｎｅａｒｏｐｅｒａｔｏｒｓｏｎＸ ,Ｂ(Ｘ ,Ｙ)ｆｏｒｔｈｅｓｅｔｏｆｂｏｕｎｄｅｄｌｉｎｅａｒｏｐｅｒａｔｏｒｓｆｒｏｍＸｔｏａｎｏｔｈｅｒＢａｎａｃｈｓｐａｃｅＹ ,ＡｆｏｒａｃｌｏｓｅｄｏｐｅｒａｔｏｒｏｎＸ ,ρ(Ａ)ｆｏｒｔｈｅｒｅｓｏｌｖｅｎｔｓｅｔｏｆＡ ,Ｄ(Ａ)ｆｏｒｔｈ…     

L~P（Ω）空间余弦算子函数的谱特征

本文得到Ｌ￣Ｐ（Ω）（１＜ｐ＜∞）空间余弦算子函数，用生成元性质表示的谱特征。     

On the Favard Class of Cosine Operator Function

61.IntroductionLetXbeaBanachspace,B(X)thealgebraofallboundedlinearoPeratoronXandC(t),t6R,thestronglycontinuouscosineoperatorfunctionsonXwithinfinitesimalgeneratorA,TheFavard(orSaturation)classorgeneralizedFav(A)ofcosineoperatorfuctionC(t)withgeneratorAisdefinedbyFav(A)={x:supl,1<,Il2t~'(C(t)-I)xllX oo}.Theestimater'P,llC(t)x-xIl=IlAJoJoC(p)xdedsIl相似文献   

Banach空间中余弦算子函数生成元的有界性

A是Banach空间X中余弦算子函数C（t),t∈R，和正弦算子函数S（t),t∈R，的生成元。本证明了，对每个f∈C（[0,T];X)，连续函数u,u(t)=∫-tS(t-s)f(s)ds,f∈[0,T]是二阶非齐次0初值问题，u″=Au f的强解的充要条件是：A是空间X中的有界算子。     

Bounded Cosine Functions Close to Continuous Scalar Bounded Cosine Functions

Let \({(C(t))_{t\in \mathbb R}}\) be a cosine function in a unital Banach algebra. We show that if \({\sup_{t\in \mathbb R}\Vert C(t)-c(t)\Vert < 2}\) for some continuous scalar bounded cosine function \({(c(t))_{t\in \mathbb R},}\) then the closed subalgebra generated by \({(C(t))_{t\in \mathbb R}}\) is isomorphic to \({\mathbb C^k}\) for some positive integer k. If, further, \({\sup_{t\in \mathbb R}\Vert C(t)-c(t)\Vert < \frac{8}{3\sqrt 3},}\) then \({C(t)=c(t)}\) for \({t\in \mathbb R}\).     

分布余弦函数

本给出分布余弦函数的定义，其中包括生成元为多值算子情形，并讨论退化性型分布余弦函数与退化型二阶Cauchy问题、退化型积分余弦函数的关系，最后说明了非退化分布余弦函数的生成元亦生成正则余弦函数。     

Subspaces of Maximal Operator Spaces

We explore subspaces of maximal operator spaces ( submaximal spaces) and give a new characterization of such spaces. We show that the set of n-dimensional submaximal spaces is closed in the topology of c.b. distance, but not compact. We also investigate subspaces of MAX(L ) and prove that any homogeneous Hilbertian subspace of MAX(L ₁) is completely isomorphic to R + C.     

On Interpolation of the Fourier Maximal Operator in Orlicz Spaces

Let and be positive increasing convex functions defined on [0, ). Suppose satisfies the 2-condition, that is, (t)2 (C1t) for sufficiently large t, and has some nice properties. If -1(u)log(u+1) C2-1(u) for sufficiently large uthen we have S*(f) L CfL for all f L ([-, ])where S*(f) is the majorant function of partial sums of trigonometric Fourier series and fL is the Orlicz norm of f. This result is sharp.     

拟微分算子与正则余弦函数

设Ｏｐｐ（ｆ）是Ｌｐ（Ｒｎ）（１ｐ＜∞）中具有象征ｆ∈Ｓｍρ，０的常系数拟微分算子．本文证明了在适当条件下，Ｏｐｐ（ｆ）在Ｌｐ（Ｒｎ）（１ｐ＜∞）中生成一个正则余弦函数，并将所得结果应用到对应的非齐次二阶Ｃａｕｃｈｙ问题．     

Baillon's Theorem on Maximal Regularity

The aim of this note is to give a proof of Baillon's Theorem on Maximal Regularity. Though it is in some sense a negative result (it states that for abstract Cauchy problems maximal regularity can occur only in very special cases), it is commonly accepted that it is important. Many people believe that its proof is very complicated. This might be due to the fact that Baillon's note in the Comptes Rendus is rather short and sometimes difficult to understand. The proof outlined here follows basically Baillon's lines. However it is simplified and (hopefully) easier to understand.     

余弦算子函数共轭性的一些结果

本文系统的给出余弦算子函数的共轭性理论，并引入了余弦函数的θ-自反概念，及给出了一些基本特征     

On Orbits of Functions of the Volterra Operator

We study asymptotic properties of certain functions of the Volterra integral operator V in L ^p [0, 1] (1 ≤ p ≤ ∞). We also prove the Ritt property under minimal spectral assumptions for some functions of V in L ²[0, 1].