一个反应扩散方程解的熄灭行为

本文应用上下解方法和Ｌ^ｐ积分模估计的方法研究了一类反应扩散方程初边值问题正解的熄灭形为，给出解熄灭的参数环境．     

关于Smale一个猜想的推广

本文对ＳｍａｌｅＳ．的一个猜想作了推广，证明了对Ｐ＞１，文［２］中的定理１没有“Ｌ^ｐ形式”     

SL(2,R)上一类极大算子的(H∞,s1,L1)型

本文我们引入了函数类B_δ(G//K)={φ∈L¹(G//K)||φ(t)|≤Δ^-1(t)(1+t)^1-δ,δ>0),对f∈L^p(G//K),1≤p≤∞,和极大算子(?),证明了这类算子是(H_∞,s¹,L¹)型的.     

可变核Marcinkiewicz积分交换子在Herz型Hardy空间上的有界性

该文研究由可变核Marcinkiewicz 积分和Lip_β (Rⁿ)(0 <β≤ 1)函数生成的交换子μ_{Ω, b}. 证明了当可变核Ω∈L^∞(Rⁿ)×L^r(S^n-1)(r≥1)$时, 交换子μ_{Ω, b}从Herz型Hardy空间到Herz空间的有界性. 同时建立了参数型Marcinkiewicz 积分的交换子μ^ρ_{Ω, b}在Herz型Hardy空间上的有界性.     

在险值与Lp-空间上的连续一致风险度量

本文研究了在险值和L^p-空间上的连续一致风险度量之间的关系.利用凸集分离定理和截尾逼近方法,获得了在险值可以用L^p-空间上的连续一致风险度量表示的结果,并且得到了L^p-空间上的表示定理的一种新的证明方法.它们分别是文献[2]的相关结论从L^∞-空间到L^p-空间上的推广和对Inoue^[4]做的一些补充证明.     

两两NQD列的Marcinkiewicz-Zygmund不等式及其应用

本文研究了两两NQD随机变量的Marcinkiewicz-Zygmund不等式及其应用的问题.利用截尾的方法,获得了两两NQD随机变量的p阶(1 ≤ p < 2) Marcinkiewicz-Zygmund不等式结果.作为应用,获得了两两NQD随机变量的两个L^r收敛性结果的简单证明,改进了陈平炎^[10]和Sung^[20]的相应工作.     

一类多线性齐性算子的Hardy空间估计 *

证明了一类带齐性核的奇异积分算子的多线性算子是乘积空间L^p1×L^p2 ×…×L^pK(Rⁿ)到Hardy空间H^r(Rⁿ)和弱Hardy空间H^{r ,∞}(Rⁿ)的有界算子 .作为应用 ,获得了一类带齐性核的奇异积分算子交换子的L^p(Rⁿ)有界性 .     

用Coulomb爆炸实测4HeD＋的键长

用1.468 0 MeV ⁴HeD^＋在超薄无衬碳膜中的Coulomb爆炸,获得⁴HeD^＋的键长实测值为(0.097±0.003)nm.讨论了⁴HeD^＋的形成机理.介绍了⁴HeD^＋原始束中D₃＋污染的降低,及产物⁴HeD^＋＋和D^＋高分辨能谱测量中的粒子鉴别方法等.     

(?)-方程的Cｐ，ｑｋ＋α-形式解及其上确界范数估计

文中研究了(?)－方程在拟凸域上的积分解算子的性质，得到了(?)－方程在具Ｃ^ｋ（ｋ≥０）类边界的拟凸开集上的Ｃ_ｐ，ｑ^ｋ＋α－形式的积分算子解及其解的上确界范数估计，它包含了文［１］仅对Ｃ^∞的情形     

d8(C3v*)EPR理论与CsMgCl3:Ni2+的光、磁性质研究

本文给出了O_h点群表象中的d^2,8(C_3v^*)完全强场矩阵,并借助于这种矩阵的特征值和特征矢量,建立了CsMgX₃:Ni²⁺(X=Cl,B,I)类晶体的全组态混合EPR理论。应用这一理论,对CsMgCl₃晶体中的Ni²⁺杂质离子的光学吸收谱、基态零场分裂参量D、顺磁g因数、基态Zeeman分裂以及EPR条件(B,hv₀)进行了统一的计算。结果与观测非常一致,从而首次对CsMgCl₃:Ni²⁺的光、磁性质作出了统一的理论解释。     

A remark on partly dissipative reaction diffusion systems on IRn

The long time behavior of the solutions of some partly dissipative reaction diffusion systems is studied. We prove the existence of a compact （L^2 × L^2 - H^1 × L^2） attractor for a partly dissipative reaction diffusion system in Rn. This improves a previous result obtained by A. Rodrigues-Bernal and B. Wang concerning the existence of a compact （L^2 × L^2 - L^2 × L^2） attractor for the same system.     

Dual frames in connected with generalized sampling in shift-invariant spaces

The aim of this article is to derive stable generalized sampling in a shift-invariant space by using some special dual frames in L²(0,1). These sampling formulas involve samples of filtered versions of the functions in the shift-invariant space. The involved samples are expressed as the frame coefficients of an appropriate function in L²(0,1) with respect to some particular frame in L²(0,1). Since any shift-invariant space with stable generator is the image of L²(0,1) by means of a bounded invertible operator, our generalized sampling is derived from some dual frame expansions in L²(0,1).     

Weyl quantization of Lebesgue spaces

We study boundedness and compactness properties for the Weyl quantization with symbols in L^q (?^2d ) acting on L^p (?^d ). This is shown to be equivalent, in suitable Banach space setting, to that of the Wigner transform. We give a short proof by interpolation of Lieb's sufficient conditions for the boundedness of the Wigner transform, proving furthermore that these conditions are also necessary. This yields a complete characterization of boundedness for Weyl operators in L^p setting; compactness follows by approximation. We extend these results defining two scales of spaces, namely L_*^q (?^2d ) and L_?^q (R^2d ), respectively smaller and larger than the L^q (?^2d ),and showing that the Weyl correspondence is bounded on L_*^q (R^2d ) (and yields compact operators), whereas it is not on L_?^q (R^2d ). We conclude with a remark on weak‐type L^p boundedness (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Translation-Invariant Bilinear Operators with Positive Kernels

We study L ^r (or L ^{r, ∞}) boundedness for bilinear translation-invariant operators with nonnegative kernels acting on functions on \mathbb Rⁿ{\mathbb {R}^n}. We prove that if such operators are bounded on some products of Lebesgue spaces, then their kernels must necessarily be integrable functions on \mathbb R²ⁿ{\mathbb R^{2n}}, while via a counterexample we show that the converse statement is not valid. We provide certain necessary and some sufficient conditions on nonnegative kernels yielding boundedness for the corresponding operators on products of Lebesgue spaces. We also prove that, unlike the linear case where boundedness from L ¹ to L ¹ and from L ¹ to L ^{1, ∞} are equivalent properties, boundedness from L ¹ × L ¹ to L ^1/2 and from L ¹ × L ¹ to L ^{1/2, ∞} may not be equivalent properties for bilinear translation-invariant operators with nonnegative kernels.     

Remark on theL2 decay for weak solution to equations of non-newtonian incompressible fluids in the whole space (I)

We study the asymptotic behaviour of the certain class of non-Newtonian incompressible fluids-power law fluids in the whole space when the external force is zero. Assuming that initial data belong toL ¹∩L ² we prove thatL ² decay in time ist ^−1/4.

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Sunto Noi studiamo il comportamento asintotico in tutto lo spazio di una classe di fluidi incomprimibili non-Newtoniani con una legge ?fluids-power? in assenza di forze esterne. Assumendo che i dati iniziali appartengano aL ¹∩L ² noi proviamo che il decadimento nel tempo inL ² èt ^−1/4.

     

Multi-window dilation-and-modulation frames on the half real line

Wavelet and Gabor systems are based on translation-and-dilation and translation-and-modulation operators, respectively, and have been studied extensively. However, dilation-and-modulation systems cannot be derived from wavelet or Gabor systems. This study aims to investigate a class of dilation-and-modulation systems in the causal signal space L²(ℝ₊). L²(ℝ₊) can be identified as a subspace of L²(ℝ), which consists of all L²(ℝ)-functions supported on ℝ₊ but not closed under the Fourier transform. Therefore, the Fourier transform method does not work in L²(ℝ₊). Herein, we introduce the notion of Θ_a-transform in L²(ℝ₊) and characterize the dilation-and-modulation frames and dual frames in L²(ℝ₊) using the Θ_a-transform; and present an explicit expression of all duals with the same structure for a general dilation-and-modulation frame for L²(ℝ₊). Furthermore, it has been proven that an arbitrary frame of this form is always nonredundant whenever the number of the generators is 1 and is always redundant whenever the number is greater than 1. Finally, some examples are provided to illustrate the generality of our results.

     

A class of multiwavelets and projected frames from two-direction wavelets

This article aims at studying two-direction refinable functions and two-direction wavelets in the setting ?^s, s > 1. We give a sufficient condition for a two-direction refinable function belonging to L²(?^s). Then, two theorems are given for constructing biorthogonal (orthogonal) two-direction refinable functions in L²(?^s) and their biorthogonal (orthogonal) two-direction wavelets, respectively. From the constructed biorthogonal (orthogonal) two-direction wavelets, symmetric biorthogonal (orthogonal) multiwaveles in L²(?^s can be obtained easily. Applying the projection method to biorthogonal (orthogonal) two-direction wavelets in L²(?^s, we can get dual (tight) two-direction wavelet frames in L²(?^m, where. m ≥ s From the projected dual (tight) two-direction wavelet frames in L²(?^m, symmetric dual (tight) frames in L²(?^m can be obtained easily. In the end, an example is given to illustrate theoretical results.     

Eigensystem of an <Emphasis Type="Italic">L</Emphasis><Superscript>2</Superscript>-perturbed harmonic oscillator is an unconditional basis

For any complex valued L ^p -function b(x), 2 ≤ p < ∞, or L ^∞-function with the norm ‖b↾L ^∞‖ < 1, the spectrum of a perturbed harmonic oscillator operator L = −d ²/dx ² + x ² + b(x) in L ²(ℝ¹) is discrete and eventually simple. Its SEAF (system of eigen- and associated functions) is an unconditional basis in L ²(ℝ).     

The effect of spatial quadrature on finite element galerkin approximations to hyperbolic integro-differential equations

The purpose of this paper is to study the effect of numerical quadrature on the finite element approximations to the solutions of hyperbolic intego-differential equations. Both semidiscrete and fully discrete schemes are analyzed and optimal estimates are derived in L ^∞(H ¹)L ^∞(L ²) norms and quasi-optimal estimate in L ^∞(L ^∞) norm using energy arguments. Further, optimal L(L ²)-estimates are shown to hold with minimal smoothness assumptions on the initial functions. The analysis in the present paper not only improves upon the earlier results of Baker and Dougalis [SIAM J. Numer. Anal. 13 (1976), pp. 577-598] but also confirms the minimum smoothness assumptions of Rauch [SIAM J. Numer. Anal. 22 (1985), pp. 245-249] for purely second order hyperbolic equation with quadrature.     

A remark on a maximal function over a Cantor set of directions

LetM _e ⁰ be the maximal operator over segments of length 1 with directions belonging to a Cantor set. It has been conjectured that this operator is bounded onL ². We consider a sequence of operators over finite sets of directions converging toM _e ⁰ . We improve the previous estimate for the (L ²,L ²)-norm of these particular operators. We also prove thatM _e ⁰ is bounded from some subsets ofL ² toL ². These subsets are composed of positive functions whose Fourier transforms have a very weak decay or are supported in a vertical strip. Partially supported by Spanish DGICYT grant no. PB90-0187.