显拟凹函数的一个新性质

显拟凹函数在非线性规划问题中起着重要的作用.在已有文献基础上给出了显拟凹函数的一个新性质:设X(∈)Rn是凸集,g:X→R是显拟凹函数,如果对(∨) y1,y2,…,yn∈X,满足g(yj)＞mini(≠)jg(yi),那么对(∨)λi＞0(i=1,…,n),n∑i=1λi=1,有g(n∑i=1λiyi)＞imini=1,…n g(yi).本文的结果推广了已有的结论.     

显拟凹函数的一个新性质 (运筹学与控制论)

显拟凹函数在非线性规划问题中起着重要的作用。在已有文献基础上给出了显拟凹函数的一个新性质:设XRn是凸集,g:X→R是显拟凹函数,如果对y1,y2,…,yn∈X,满足g(yj)>min i≠j g(yi),那么对λi>0(i=1,…,n),n∑i=1λi=1,有g(n∑i=1λiyi)>min i=1,…n g(yi)。本文的结果推广了已有的结论。     

用不等式刻画的线性函数

应用有限维实数组，即A1={[λ1]=(λ1，λ2，…，λn)，λi∈R，i=1，2，…，n}，n↑∑↑i=1λi=1和A↓xi∈R，i=1，2，…，n满足Jensen不等式的凸函数f：f(n↑∑↑i=1λixi)≤n↑∑↑i=1λif(xi)，刻画了线性函数与仿射函数。     

变时滞的Hopfield网络模型的全局指数稳定性

研究了其时滞是在更一般的时间变量的函数情况下的Hopfield网络系统:(*)/(x)i(t)=-cixi(t)+∑n j=1aijfj(xj(t))+∑n j=1bijfj(xj(t-τj(t)))+Ii,i=1,2,...,n.在非线性神经激励函数满足较弱的Lipschitz条件下,引入Lyapunov函数,利用不等式技巧和泛函的单调性等,研究了具有变时滞的Hopfield网络系统的稳定性,得到了对每一个输出响应函数fj(*)在R上有定义,且连续的情况下,系统有唯一的平衡点X=X*,并且该平衡点是全局指数稳定的一个易于判定的充分条件.     

关于E-凸集合的一个定理

我们已经知道，如果X是n维欧氏空间中的一个非空子集且满足：X=∪i=1^nXi(Xi,i=1，2，…，n是n维欧氏空间中的凸子集)．在一定的条件下，若e^pXi是凸集，则集合X是P-不变凸集．本文在E-凸集的条件下得到了相似的结论，推广了文献[3]中命题2．3的结论，从而产生了一些讨论E-凸集和E-凸函数的有用工具．     

三阶线性中立型时滞差分方程非振动解的存在性

考虑具有正负系数的三阶中立型时滞差分方程 Δ^3[x（n）＋px（n-τ）]＋R1（n）x（n-δ1）-R2（n）x（n-δ2）=0 这里p∈R；τ∈N（1）；δ1，δ2∈N；{R1（n）），（R2（n））是正实数序列。得到了上述方程在条件∑n=1^xn^2R1（n）〈＋∞，i=1，2，n∈N（n0）之下最终正解的存在的一个充分条件。这个结果去掉了现有文献中一个相当强的假设，改进了其中的相关定理。     

分布自由的回归函数核估计的收敛速度

设(X1,Y1)、(X2,Y2)、…是取值于Rp×R上的随机向量(X,Y)的一列i.i.d样本,回归函数m(x)=E(Y|X=x)的核估计为mn(x)=n∑i=1 YiK(x-Xi/hn)/n∑i=1 K(x-Xi/hn)在不要求X具有密度函数f(x),对分布自由,即对所有X的分布μ和在核函数改进为包括无界支撑的,甚至不可积的情形下得出了回归函数m(x)=E(Y|X=x)的核估计及在删失情形下的收敛速度.     

最大最小顺序统计量的相关结构

(X_1,Y_1),(X_2,Y_2),…,(X_n,Y_n)为来自二维总体(X,Y)的简单随机样本,(X,Y)具有分布函数H(x,y),X(1)=min1≤i≤n{X i},X(n)=max1≤i≤n{X i},Y(1)=min1≤i≤n{Y i},Y=(28)max1≤i≤n{Y i}﹒利用Copula研究了(X(1),Y(n))、(X(1),Y(1))及(X(n),Y(n))的相关结构,并举例说明了其应用﹒事实表明,最大最小顺序统计量的相关结构包括常见的积Copula和FGM等,为构造Copula提供了新思路﹒     

强相依平稳正态序列的部分和与最大值的联合极限分布

设X1，X2，…是标准化平稳正态序列，协方差ρn=EX1Xn 1。在ρn和（ρnlogn)^-1都单调且收敛到0的情况下，得到了∑i=1nXi与max{Xi|1≤i≤n}的联合渐近分布。     

保持矩阵Frobenius范数的乘法映射

设Γn是满足{aEij|i,j=1,2,…,n,a∈R}(∪)Γn(∪)Mn(R)的一个乘法半群,其中Mn(R)定义R上所有n×n矩阵组成的乘法半群,证明了若f : Γn→Mn(R)是一个保Frobenius范数映射,则存在正交阵U∈Mn(R),使得U'f(A)=U-1f(A)U=A,(A)A∈Γn.     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

英文诗歌中的喻类修辞

为了有助于提高英文爱好者的个人情操、文化素养和学习兴趣,以及专业人员对英语学习和研究进行多途径的探索,本文通过一些精选诗歌的引证和分析,着重论述了喻类修辞法在英文诗歌中的运用其及效果。     

Man Is Unable to Change the Miserable Life——Analysis of the Arrangement of Four Characters in The Glass Menagerie

Tennessee Williams is considered as one of the most important American playwrights since World War II.The Glass Menagerie is his first successful drama,which describes a tragic situation of family and means to say that Man is unable to change the miserable life,no matter whatever means he try,This essay focuses on the analysis of the arrangement of the four main characters:Laura.Amanda,Jim and Tom to reveal the theme.Laura is fragile.Amanda is brave.Jim is vital.Tom is sensible.And all of them develop and try the different means to struggle against life,but fail tragically.With the evidence,the paper comes to conclusion naturally that Man is unable to change the miserable life,and he dooms to fail.     

Characterization of root-nodulating bacteria on Retama raetam in arid Tunisian soils

The aim of this study is to investigate the diversity of Retama raetam root-nodule bacteria isolated from arid regions of Tunisia. Twelve isolates, chosen as representative for different 16S rRNA gene patterns, were characterized by 16S rRNA gene sequencing and phenotypic analysis. Isolates were assigned to Sinorhizobium, Rhizobium and Agrobacterium. Symbiotic properties of Sinorhizobium and Rhizobium isolates showed a large diversity in their capacity to infect their host plant and fix atmospheric nitrogen. Strain RK 22 identified as Rhizobium was the most effective isolate.     

An Affordable Accurate Evaluation of the Binding Conformations Predicted by Molecular Docking Studies in Bio-System

正Recently,docking has been widely used to predict the binding-modes of protein-inhibitors,when the crystal complexes structure was absent.Most docking algorithms are able to generate a large number of probable conformations,it,however,is difficult to effectively evaluate these docking poses and identify the most reasonable bindingmode.In the present study,on the basis of the crystallographic data of human 3-hydroxy-3-methylglutaryl coenzyme     

WIMAX与WI-FI技术分析及联合组网

介绍了WiMAX与Wi-Fi两种无线宽带接入技术,并对两者之间的关系及相互之间的影响做了对比及分析,并对WiMAX的关键技术进行了详细说明,最后对两者的联合组网方式做了简单的探讨。