无压流圆形断面收缩水深的近似计算公式

无压流圆形断面收缩水深的计算需求解高次隐函数方程，理论上无解析解，传统的图解法或者试算法计算过程复杂，费时费力．通过引入无量纲收缩水深，对无压流圆形断面收缩水深的基本方程进行恒等变形，得到了快速收敛的迭代公式，再与合理的迭代初值配合使用，得到无压流圆形断面收缩水深的近似计算公式．误差分析及实例计算表明，在工程常用范围内，收缩水深的最大相对误差小于0．72％．近似计算公式形式筒捷、精度高、适用范围广．     

迭代法在明渠流水深计算中的应用

鉴于明渠流水力计算中正常水深和临界水深，用试算法计算繁琐，用查图法查算精度较低，本文通过对水力学中流量和水力要素计算公式的数学变形，导出矩形、梯形断面正常水深和临界水深的迭代关系式，并以实例应用说明迭代算法的优点。     

求解一类矩阵方程最佳逼近解的算法

应用复合最速下降法，给出了在加权范数下求解矩阵方程AXB＋CYD=E的对称最佳逼近解的一种迭代算法。在有限的误差范围内，对任意初始矩阵X0、Y0，运用迭代算法，经过有限步可得到矩阵方程的最佳逼近解，并给出的数值例子证实了该算法的有效性。     

无小参数非线性振动方程的近似方法

本文提出了一种求解非线性方程的迭代算法 ,它不依赖于小参数 ,是先给方程一个带待定函数的试函数作为初始近似解 ,然后用拉氏乘子法构造一个迭代公式 (校正泛函 ) .试函数中的待定函数可用变分直接方法确定 ,而校正泛函中的拉氏乘子可用变分理论最佳确定 .应用这种方法不会出现长期项 ,其结果表明这种新方法是比较有效的 .     

应用解析法计算换热器的流体出口温度

流体出口温度的计算是换热器计算的一大难点,以往方法中存在着试差的繁琐和图表的误差,通过公式建立了解析的数学方程,其应用结果准确,算法符合化学工程计算中运用计算机进行计算的要求。     

分数阶Rosenau-Haynam方程的残差幂级数解法

为了解决分数阶微分方程在多数情况下很难得到其解析解的问题,给出了一种求解时间分数阶Rosenau-Haynam方程近似解析解的方法——残差幂级数法(RPSM)。首先将分数阶Rosenau-Haynam方程用分数阶幂级数展开至n项,然后再将展开后的表达式带入到方程中,利用残差函数的(n-1)α次导数为0即可求得近似解。通过与变分迭代法所得的解作比较,结果表明残差幂级数法所得解析解的误差更小。     

灰色GM(1,1)模型的图解法

灰色GM(1,1)模型是GM模型中最基础、最核心、应用最广泛的一种预测模型.本文提出了确定GM(1,1)模型基本解有关待定参数的一种新方法——图解法.该方法能方便地确定GM(1,1)模型解的有关待定参数,既简明又直观.将图解法与解析法进行比较,结果表明,图解法与解析法的精度基本接近,能够满足工程控制的需要.     

一类Fredholm-Hammerstein型泛函积分方程不动点迭代与Aitken加速迭代算法

利用Banach不动点原理,给出了一类Fredholm-Hammerstein型非线性泛函积分方程解析解的存在唯一性定理.分别给出了不动点迭代与Aitken加速迭代的数值算法、误差估计、收敛性分析.最后通过两个数值例子验证了收敛性定理的有效性,并得到两种算法的比较分析结果.     

一类具有二阶导数的广义迭代微分方程的解析解

讨论一类具有二阶导数的广义非线性迭代方程．通过Schrsder变换将其化为它的辅助方程，利用优级数证明其局部解析解的存在性，并根据SchrtMer变换中参数卢的不同情况进行讨论．不仅讨论一般的情况，而且讨论临界情况，特别是当β是单位根时，此类方程在迭代理论和应用方面都有重要意义．     

第二类Fredholm积分方程的多项式多投影算法

主要讨论第二类Fredholm积分方程的多项式多投影算法.算法应用到Galerkin方法和配置法两种情况,并证明当核函数和方程的解具有一定的光滑核性时,多投影算法的近似解及其迭代解的精度分别是一般有限维投影法近似解的三倍和四倍,表现出算法具有非常高的超收敛性.     

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。