多重时滞不确定系统的鲁棒稳定判据

本文主要研究了一类具有范数有界不确定性的多重时滞不确定系统的鲁棒渐近稳定性分析问题.分别给出了多时滞不确定系统和单时滞不确定系统的时滞独立鲁棒稳定充分判据.此判据只利用了范数的概念,便于实用.     

一类不确定离散时滞系统的鲁棒镇定

考虑了一类具有多胞型不确定离散时滞系统的鲁棒稳定及控制器设计问题.文章首先得出了新的时滞相关的稳定性判据,然后在此基础上设计了鲁棒镇定反馈控制器,所得结果用矩阵不等式给出,最后通过数值算例表明该方法的有效性.     

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;...     

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 .     

不确定变时滞非线性随机系统的鲁棒稳定性

探讨了同时具有分布时滞和离散时滞的凸多面体不确定非线性随机系统的鲁棒稳定性.利用随机Lyapunov稳定性理论和自由权矩阵方法,基于参数依赖的Lyapunov-Krasovskii泛函,获得了系统的时滞相关及参数相关的鲁棒稳定性的充分条件,并以线性矩阵不等式的形式给出了系统的稳定性判据.最后用算例说明了文中方法的有效性.     

具有时变时滞的不确定大系统鲁棒稳定性的简捷判据

用Lyapunov泛函方法讲座了具有时变时滞的不确定线性大系统的鲁棒稳定性得到了具有时变时滞的不确定线性大系统鲁棒稳定性的简捷判据.最后,给出了本文结论的两个示例并与前人的结论作出了比较.研究结果表明结论给出的条件在判时变时滞的不确定线性大系统的鲁棒稳定性时较前人的相关结论更为有效.参9.     

具多时滞的LURIE型不确定控制系统的时滞相关鲁棒稳定性判据

对于具有多个时变时滞的ＬｕｒｉｅＫ型不确定控制系统的鲁棒稳定性问题进行研究,给出了该系统时滞相关鲁棒稳定性判据。最后给出一个例子说明本文结果。     

一类不确定时滞系统与时滞相关的鲁棒稳定性

考虑一类状态和输入均带有滞后的不确定时滞系统,研究其鲁棒稳定性,采用Lya-punov泛函法和线性矩阵不等式(LM Is)方法,给出不确定时滞系统与时滞相关的鲁棒稳定性的充分条件,并给出了鲁棒稳定的设计方法.     

不确定离散时滞系统的时滞无关鲁棒状态反馈控制

研究了一类同时具有状态时滞和输入时滞的离散不确定系统的鲁棒稳定性问题.利用Lyapunov方法,结合矩阵不等式性质,给出可设计系统状态反馈控制律的充分条件,且是时滞无关的.所得结果基于相应的线性矩阵不等式(LMI)的解,并用算例验证了结果的有效性.     

不确定离散时滞大系统的鲁棒稳定性

对于一类具有时变时滞以及非线性不确定性的离散大系统,考虑了其鲁棒稳定性问题.基于Lyapunov泛函方法及矩阵范数不等式方法,提出了这类时滞大系统的时滞无关鲁棒稳定性判据,所得判据条件由一族Lyaunov方程以及代数不等式给出,计算简单,验证方便.最后以一个数值实例表明了本文所得结论的正确性.     

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.     

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