特征值的上下限和求特征值的一个迭代算法

本文在已知某近似特征对的基础上,给出了一个简单和有效的求特征值上下限的方法,并且近似特征值肯定属于上下限之一.此外,文中还提供了一个矩阵特征值问题的从单边逼近精确值的迭代算法.     

用幂法求方阵特征值的一个注记

用幂法求方阵的近似特征值和近似特征向量的主要作法如下:设A为给定的方阵,任取初始向量x_0,作向量序列x_k+1=Ax_k,(k=1,2,…)。若x_(k+1)和x_k的对应分量近似成比例,则这个比例系数就是A的特征值的近似值,而x_(k+1)就是相应的近似特征向量。在许多计算方法的教科书中,上面的幂法被称做求按模最大的特征值的一个方法。的确,在一定条件下,当k充分大时,x_(k+1)和x_k近似成比例,且其比例系数趋向于A     

一个施图姆-刘维尔方程最大特征值的逼近公式

改进了一种计算施图姆-刘雏尔方程大特征值的方法,运用泰勒展开对渐进公式中的奇异积分项进行近似,并且由于大特征值对应的特征函数具有较多零点这一特性,用系数在某点的取值来近似代替该周期的变化.对一类非常系数的施图姆-刘雏尔方程的大特征值分布和逼近有较好的计算结果.考虑系数的变化,得到了一个改进的大特征值计算公式.算例表明,考虑扰动项的改进公式同样可以取得较好的计算结果.     

关于Rayleigh商矩阵近似特征值估计

借助于谱分解定理以及矩阵理论中的特征值的排序,优于等相关性质定理来研究Hermite矩阵近似特征向量与相应的Rayleigh商矩阵作为近似特征值之间的关系,进行特征值的扰动分析,并推广了一个应用广泛的结论.     

约束优化问题中LP最小值序列的性质和判定

借助于谱分解定理以及矩阵理论中的特征值的排序,优于等相关性质定理来研究Hermite矩阵近似特征向量与相应的Rayleigh商矩阵作为近似特征值之间的关系,进行特征值的扰动分析,并推广了一个应用广泛的结论.     

求解Toeplitz矩阵特征值反问题的不精确牛顿方法

研究了求解大型Toeplitz矩阵特征值反问题的数值方法。用迭代方法(内迭代)求这些线性方程组的近似解,给出了求解大型Toeplitz矩阵特征值反问题的不精确牛顿方法。该方法可避免牛顿方法的“过度求解问题”,改进牛顿方法的有效性。数值结果表明不精确牛顿方法优于牛顿方法。     

解双曲型方程的Lanczos方法

本文利用Lanczos τ—方法的思想,将求双曲型方程近似解的问题,代之以求一个摄动方程的近似解,最后将问题归结为代数特征值问题。这样求得的近似解析解,使我们能够在大范围内求得解的近似值。     

求解对称矩阵特征问题的精化Arnoldi方法

研究在有限精度下,如何用精化Arnoldi方法求对称矩阵的一组正交程度可达到机器精度的近似特征向量组.首先给出精化Ritz向量的一个新的表达式,该表达式表明理论上对不同的近似特征值,一般地无法保证精化Arnoldi方法所确定的精化Ritz向量组是正交的.进一步,采用再正交化方法便可得到一组正交化程度可达到机器精度的标准正交近似特征向量组,最后的数值结果验证结论的准确性,同时再正交化后得到新的近似对的残量几乎是不变的.     

关于Steklov特征值问题非协调元逼近的一个注记

探索了凹角域上Steklov特征值问题的非协调元逼近.数值实验结果表明用非协调Crouzeix-Raviart元、Q1rot元、EQ1rot元求得的近似特征值具有三角线性协调元的精度阶,而且可能下逼近于准确特征值。     

基于小波包分解和近似熵的脑电信号分类

为提高脑电信号分类准确率,提出基于小波包分解和近似熵相结合的特征提取方法。该方法利用小波包对信号的低频和高频进行分解,用近似熵对得到的叶子结点进行计算得到特征值,然后将其输入支持向量机进行分类。实验结果表明,该方法在两种思维结合识别中正确率最高达到了97.37%,取得了较好的分类效果。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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