切换系统区间时滞依赖稳定及L_2增益分析

研究具有时变时滞不确定切换系统的区间时滞依赖鲁棒指数稳定性及系统满足L2增益性能分析.系统具有的时变时滞下界可以不为零.利用平均驻留时间方法和自由权矩阵方法,给出了切换系统区间时滞依赖鲁棒指数稳定及满足相应L2增益的充分条件,也给出了切换律的设计.将切换系统的稳定性和满足L2增益性能问题的条件归结为一组线性矩阵不等式的可解性问题.最后通过仿真验证了结论的正确有效性.     

一类带有时变时滞和非线性扰动的切换系统的鲁棒指数稳定性（英文）

讨论了一类带有时变时滞和非线性扰动的切换系统的鲁棒指数稳定性问题。通过构造新的李雅普诺夫-克拉索夫斯基函数研究切换系统的稳定性,同时考虑了时变时滞对系统稳定性的影响。在系统分析过程中,采用自由权矩阵的方法,提高问题的可解性并使结果具有更小的保守性,切换策略采用平均驻留时间的方法,未知的非线性扰动采用通常的限制方法。根据Lyapunov稳定性定理,得到了切换系统时滞依赖鲁棒指数稳定性的充分条件。该判定条件不易检验,利用Schur补引理可以把这个条件化成等价的易于求解的线性矩阵不等式形式,从而获得该类系统鲁棒稳定性的切换控制策略。     

具有离散与分布时滞神经网络鲁棒稳定性

针对一类具有离散与分布时滞的神经网络存在的鲁棒稳定性问题,考虑时滞与参数扰动等不确定因素,通过加入三重积分条件,构造合理的Lyapunov-Krasovskii泛函,并采用线性矩阵不等式技术.研究结果表明:得到系统全局指数鲁棒稳定的时滞相关充分条件,同时能够得到系统全局渐进鲁棒稳定的充分条件,表明了该方法的有效性和可行性.     

离散多时滞系统时滞记忆鲁棒H_∞容错控制

针对具有多个时滞状态的线性不确定离散时间系统,基于李雅普诺夫稳定性理论和线性矩阵不等式方法（LMI）,采用有时滞记忆的状态反馈控制律,研究了执行器发生故障的情况下,不确定离散多时滞系统的鲁棒H∞容错控制问题.在采用离散执行器故障模型条件下,给出了没有干扰输入时,系统存在有时滞记忆的状态反馈鲁棒容错控制器的一个充分条件;...     

一类不确定时滞离散模糊切换系统的鲁棒稳定性问题

研究了一类不确定时滞离散模糊切换系统的鲁棒稳定性问题。基于模糊Lyapumov-Krasovekli函数,采用并行部分补偿算法,设计了使模糊系统全局渐近稳定的控制器,提出并证明了一个新的判别闭环不确定离散时滞模糊切换系统鲁棒渐近稳定的充分条件。     

带非线性扰动的不确定多时滞系统时滞相关鲁棒稳定性

利用矩阵不等式技巧,得到了一个新的具非线性时变扰动的不确定多状态时滞系统的鲁棒稳定性判据．系统中的时滞是未知定常的,时变参数的不确定项是范数有界的,而非线性扰动项满足一定的线性约束．基于矩阵不等式技巧和Lyapunov泛函方法,得到了以线性矩阵不等式(LMI)形式给出的时滞相关鲁棒稳定性判据．最后,通过两个示例表明,与文献方法相比,采用文中所提方法可减少结果所存在的保守性．证明了文中方法的有效性．     

不确定区间时滞Markov跳变BAM神经网络的鲁棒指数稳定性

讨论了具有不确定区间时滞的BAM神经网络的鲁棒均方指数稳定性问题。通过构造适当的Lya-punov-Krasovskii泛函,利用一些新的定界技术,以线性矩阵不等式形式给出了Markov跳变BAM神经网络的时滞且区间相关的全局鲁棒指数稳定性判据,该判据利用Matlab的LMI工具很容易进行检验。给出数值示例,说明了判据的有效性与优越性。     

不确定区间时滞Markov跳变BAM神经网络的鲁棒指数稳定性

讨论了具有不确定区间时滞的BAM神经网络的鲁棒均方指数稳定性问题.通过构造适当的Lyapunov-Krasovskii 泛函,利用一些新的定界技术,以线性矩阵不等式形式给出了Markov跳变BAM神经网络的时滞且区间相关的全局鲁棒指数稳定性判据,该判据利用Matlab的LMI工具很容易进行检验.给出数值示例,说明了判据的有效性与优越性.     

一类线性时变时滞不确定系统的鲁棒稳定性和H∞性能

讨论了一类具有不匹配不确定性的线性时变时滞系统的鲁棒稳定性和鲁棒H∞性能问题,对于给定的不确定性,以矩阵不等式的形式给出了时变时滞不确定系统渐近稳定的条件和系统满足H∞性能的条件.     

Lurie型不确定控制系统的鲁棒稳定性

利用Razumikhin技术与向量不等式的方法 ,研究具有多个状态和控制的时变时滞的Lurie型不确定控制系统的鲁棒稳定性问题 ,给出了系统鲁棒绝对稳定的时滞相关及时滞无关判据 .并通过优化参数得到具有较低保守性的时滞相关准则 .还给出一个例子 .     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

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