线性切换系统二次稳定性分析与设计

基于区间矩阵的等价表示方法,把线性切换系统转化为区间系统,利用矩阵不等式得到了在任意的切换策略下线性切换系统二次稳定性的充分条件,给出了控制器的实现算法.这个条件等价于共同二次正定Lyapunov函数判定条件,但共同二次正定Lyapunov函数判定条件需要求解若干个矩阵不等式,当子系统较多时计算量是相当大的,而这个条件只需找到一个Riccati不等式的的正定解就可以判定该系统的二次稳定性,大大降低计算工作量.用数值例子对所得结果加以验证,说明了文中结果的正确性.     

区间矩阵Hurwitz稳定的充分及充要条件

区间矩阵稳定性问题是控制理论中十分棘手又无法回避的问题.利用向量比较原理,讨论了连续区间系统的稳定性,得到了区间矩阵Hurwitz稳定的充分(充要)条件.如果由区间矩阵端点构造的检验矩阵A0 D Hurwitz稳定,则区间矩阵Hurwitz稳定.     

区间矩阵系统的保低成本鲁棒容错控制

为了使区间矩阵容错控制系统具有鲁棒稳定性，且具有低保守性，提出了确定实对称阵集合最小上界的方法．利用最小上界及矩阵Riccati方程，给出了系统矩阵和输入矩阵均合有不确定性时，区间矩阵系统有限时间及无限时间保低成本鲁棒容错控制器设计方法．该设计方法把确定多个Riccati不等式共同解的复杂问题简化为求解单一Riccati方程，所得到的鲁棒容错控制器可使系统具有低成本保证值，方法简便易行．文中具体算例表明了该方法的有效性．     

区间矩阵Hurwitz稳定的充分及充要条件

区间矩阵稳定性问题是控制理论中十分棘手又无法回避的问题。利用向量比较原理，讨论了连续区间系统的稳定性，得到了区间矩阵Hurwitz稳定的充分(充要)条件。如果由区间矩阵端点构造的检验矩阵A0 D Hurwitz稳定，则区问矩阵Hurwitz稳定。     

一类结构不确定系统的摄动反馈分析与设计

对一类对象和控制器同时具有结构不确定摄动的闭环系统的鲁棒稳定性分析与设计问题进行了研究。利用Riccati不等式、H∞ 范数及矩阵分解等方法 ,得到了系统不确定参数的一种鲁棒稳定摄动界。进一步给出了已知系统参数摄动界时的标称控制器的设计方法。     

一类结构不确定系统的摄动反馈分析与设计

对一类对象和控制器同时具有结构不确定摄动的闭环系统的鲁棒稳定性分析与设计问题进行了研究。利用Riccati不等式、H∞范数及矩阵分解等方法，得到了系统不确定参数的一种鲁棒稳定摄动界。进一步给出了已知系统参数摄动界时的标称控制器的设计方法。     

动态离散区间系统的Robust稳定度

研究了动态离散区间系统的Robust稳定度问题。首先提出Schur稳定度、离散线性系统的渐近稳定度及离散区间系统的Robust稳定度的概念 ;而后运用矩阵理论 ,仅依据状态区间矩阵的界阵 ,获得了离散区间系统具有Robust稳定度的简便实用的充要条件。这些结果作为相应地稳定性 (h =0时 )的判据 ,推广了现有文献 (M E Sezer ,IEEETrans .Automat .Contr .1994 ;彭晓林 ,科学通报 ,1991)的结论 ,扩展了使用范围。此外 ,还给出由 12 (A +AT)的Schur稳定来推断A为Schur稳定的条件。     

一类无界时变区间矩阵的稳定性分析

利用Coppel's不等式对无界时变区间矩阵和具有分解的无界时变区间矩阵的稳定性进行了研究, 给出了区间矩阵稳定的充分条件.最后通过两个数值实例说明了所给方法的有效性.     

几个区间矩阵稳定性的充分条件

论述了关于区间矩阵稳定性的问题.通过对测试矩阵Wh是否为一非奇异的M矩阵的判断,得到了几个区间矩阵稳定的充分条件.并且,在Kyfan定理和Ostrowski定理的基础上,对区间矩阵的稳定性的判定得出了几个充分条件.     

区间Delta算子系统的鲁棒H∞控制

研究了基于Delta算子描述的区间系统鲁棒H∞镇定设计问题。在给出了区间系统的一种等价描述后，利用H∞控制的思想，将系统的鲁棒镇定设计问题化为求解Riccati不等式。所设计的控制器可使闭环系统鲁棒稳定，而且对可允许的参数变化具有一定的H∞性能。所得结论可将连续与离散区间系统的有关结果纳入到Delta算子系统的统一框架中。     

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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