一类不确定切换模糊系统的鲁棒可靠自适应控制

提出了一类不确定切换模糊系统的模型并研究其鲁棒镇定问题,模型中的每个子系统均为不确定模糊系统.对于系统的外部干扰具有未知上界的情况,当执行器"严重失效"而未失效部分不能镇定原系统时,使用切换技术和多Lyapunov函数方法构造出模糊鲁棒自适应可靠控制器,使得相应的闭环系统对所有可能的不确定性和所有允许的执行器失效一致最终有界,同时设计了可以实现闭环系统一致最终有界的切换律.仿真结果表明了所设计方法的可行性与有效性.     

一类不确定切换模糊系统的自适应鲁棒跟踪控制

提出了一类新的不确定切换模糊系统,即切换系统中的每个子系统都是不确定模糊系统.与传统的模糊切换系统不同,这类系统并没有分为两级结构,而是由多个子系统构成,并在子系统之间进行切换.采用多Lyapunov函数研究不确定切换模糊系统的鲁棒跟踪问题,针对模型中未知上界的外部干扰,设计全局鲁棒控制器及其自适应律,并给出使该系统的跟踪误差一致渐近趋于零的切换策略.仿真表明,当自适应参数的在线慢调节与切换律的在线快调节相结合时,能提高系统的暂态响应性能.     

一类不确定离散切换模糊时滞系统的鲁棒输出反馈控制

针对状态不可观测的情况,重构系统状态,提出了一类不确定离散切换模糊时滞系统的鲁棒镇定问题.考虑每个切换子系统都是模糊系统的切换系统模型,利用切换技术,对于系统状态采用多Lyapunov函数方法,对于观测器误差采用共同Lyapunov函数方法,给出了切换律设计.利用平行分布补偿算法(PDC),给出了基于观测器的切换模糊反馈控制器设计,使得闭环系统对所有允许的不确定性,在所设计的反馈控制器和切换律下具有鲁棒性.最后通过数值仿真例子验证了该设计方法的有效性和可行性.     

参数不确定马尔可夫跳变系统的镇定控制算法研究

研究了具有参数不确定的线性马尔可夫跳变系统的鲁棒适应控制问题。对于切换律是可观测的情形,利用线性矩阵不等式和共同2次Lyapunov函数的方法,给出具有参数不确定的切换系统2次镇定的充分条件。基于此结果,对于切换律符合不可观测的马尔可夫随机过程的情形,通过设计一个恰当的采样适应控制器得到系统随机可镇定的充分条件。最后,通过一个例子给出适应镇定控制器的算法。     

基于混杂切换方法的离散切换系统状态反馈H∞控制

利用时变Lyapunov函数考虑离散切换系统的H∞控制问题.针对每个子系统都不稳定的问题,设计了一个同时依赖状态和时间的切换律.在该切换律下,得到了系统稳定性、l2增益性能及控制器设计的条件.当没有驻留时间约束时,该方法就退化为最小切换,故所提方法为离散切换系统的分析提供了更一般的框架.此外,去掉了对每个子系统的H∞控制问题可解性的要求.     

一类不确定线性切换系统的鲁棒镇定

研究了一类不确定线性切换系统基于状态反馈的鲁棒镇定问题.此类切换系统不仅具有未知时变但有界的结构不确定性,还具有不满足匹配条件的外部扰动.首先利用完备性条件与共同李亚谱诺夫函数方法,在各子系统不需满足镇定的条件下,设计了切换系统的状态反馈鲁棒控制器及相应的切换策略,使不确定线性切换系统的状态在其平衡点处渐近稳定,得到了切换系统可状态反馈镇定的充分条件;然后基于凸组合技术与线性矩阵不等式方法,将所得结果用易于求解的线性矩阵不等式的形式表出;最后通过仿真例子表明所设计的状态反馈控制器在给定的切换策略下,可使不确定切换系统的状态达到渐近稳定.     

一类线性切换系统基于观测器的输出反馈镇定

对一类线性切换系统 ,首先设计了其状态观测器的形式 ,给出线性切换系统渐近镇定的一组LMI形式的充分条件 .基于所设计的观测器 ,用各子观测器的值构造各子控制器和切换策略 ,达到使整个闭环系统渐近稳定的目的 .对切换时间周期受限制情况 ,给出其相应的指数镇定控制策略 .最后给出一个仿真实例以说明本文设计方法的正确性 .     

一类线性不确定系统基于切换的输出反馈镇定

对一类不确定线性系统,通过控制器切换研究混杂输出反馈鲁棒镇定问题。假设存在有限个备选的控制增益已知的控制器,并且任何单一的输出反馈控制器都不能镇定系统。基于单Lyapunov函数的方法,给出了混杂输出反馈控制器的切换律设计方案,使得闭环系统对所有允许的不确定性,在所设计的切换律下是渐近稳定的,并应用线性矩阵不等式（LMIs）的可解性给出了闭环系统鲁棒镇定的充分条件。最后用仿真验证了文中方法的有效性。     

具有变时滞摄动切换系统的鲁棒状态反馈镇定

探讨了具有变时滞摄动切换系统的鲁棒状态反馈镇定问题.利用单Lyapunov函数方法和多Lyapunov函数方法,设计了使系统镇定的鲁棒状态反馈镇定控制律和切换策略.仿真结果表明,所设计的控制律和切换策略正确、有效.     

一类不确定切换模糊系统的鲁棒控制

针对不确定的模糊系统,提出一类不确定切换模糊系统的鲁棒控制问题.使用切换技术及Lyapunov函数方法构造出连续状态反馈控制器,使得对于所有允许的不确定性,相应的闭环系统渐近稳定,同时设计可以实现系统全局渐近稳定的切换律.模型中的每个切换系统的子系统是不确定模糊系统,取常用的平行分布补偿PDC控制器,主要条件以凸组合的形式给出,具有较强的可解性.这类混杂控制系统对参数变化具有很强的鲁棒性.计算机仿真结果表明设计方法的可行性与有效性.     

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     

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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Brief Introduction to “Journal of Jilin University( Science Edition) ”

<正>"Journal of Jilin University(Science Edition)"is a comprehensive academic journal in the fields of science sponsored by Jilin University and administrated by the Ministry of Education of the Peoples Republic of China.The journal started publication in 1955.The original name at starting publication was"Journal of Natural Science of Northeast People University",which was changed into"Acta Scientiarum Naturalium Universitatis Jilinensis"in 1958 owing to the name change of the university.The present journal name has