不确定输入时滞系统的滞后相关型鲁棒H∞控制

针对带有输入时滞的不确定线性时滞系统,基于适当形式的Lyapunov泛函,利用线性矩阵不等式方法讨论了时滞相关型鲁棒H∞状态反馈控制器设计问题,其中不确定性是时变未知的,满足范数有界条件,且控制器存在的充分条件由线性矩阵不等式的形式给出.给出了一个应用实例,并与已有结果进行了比较.与通常所采用的导出时滞相关型鲁棒H∞状态反馈控制器的设计方法相比,只需进行两次矩阵不等式的放大,就可得到相应的控制器设计方案.仿真结果表明控制器设计方案具有较小的保守性.     

多时滞不确定系统的鲁棒指数镇定

基于新型稳定性分析技术及线性矩阵不等式方法,研究了含有参数不确定性的线性多时滞系统的鲁棒指数镇定问题.首先,对不含参数的不确定性时滞系统设计无记忆状态反馈控制器,给出了在该控制器作用下,闭环系统指数稳定的线性矩阵不等式形式的充分条件;然后,将其推广到含有范数有界参数不确定性的时滞及多时滞线性不确定系统,得到了保证系统鲁棒指数稳定的充分条件,并提供了指数衰减度及衰减因子的估计方法.所给出的判据避免了现有文献中对时变时滞导数小于1的要求,比已有的结果具有更少的保守性,数值例子验证了本方法的有效性.     

带马尔科夫调制的双线性随机时滞系统的均方渐近稳定性

利用线性矩阵不等式与Lyapunov直接法研究了一类带马尔科夫调制的双线性随机时滞系统的稳定性,这类系统的状态中包含范数有界的不确定参数以及未知的时滞,得到了该系统均方渐近稳定的充分条件．     

一类混合时滞系统对时滞参数的自适应控制

研究了一类较为复杂的混合时滞系统——被控状态为连续形式且状态时滞参数未知,而控制输入为离散序列.在分别建立了连续与离散的模型基础上,根据已有的混合系统的稳定性定理及一种Lyapunov-Krasovskii泛函方法,提出了一种镇定系统的方法,并得到了离散形式的可用于控制输入的对未知时滞参数的自适应律.在该自适应律作用下,未知时滞参数能始终反映在带记忆状态反馈控制器中,依赖于时滞的反馈控制器存在的充分条件可通过一组线性矩阵不等式(LMIs)表示.     

不确定广义时变时滞系统的鲁棒H_∞控制

针对具有时变时滞和线性分式参数不确定性广义系统,研究基于状态反馈的鲁棒H∞控制问题.利用增广Lyapunov泛函并结合自由权矩阵方法,保留了Lyapunov泛函导数中的时滞上界信息,得到时变时滞广义系统的一个新的有界实引理(BRL).在此基础上,给出不确定广义时变时滞系统H∞状态反馈控制律的一个直接设计方法.所给结果均以严格线性矩阵不等式(LMI)表示.数值实例表明了结果的有效性和较小保守性.     

具头胞型不确定性时滞系统的鲁棒控制

探讨了一类带有头胞型不确定性非线性时滞系统的鲁棒镇定问题,利用参数相关的Lyapunov泛函,设计了状态反馈控制律使闭环系统鲁棒稳定.以线性矩阵不等式形式给出主要结果,所期望的状态反馈控制律可通过求解给定的线性矩阵不等式得到.所得结论是时滞相关的,保守性相对较小.     

具有状态和控制时滞的不确定线性系统的鲁棒镇定

针对仿射参数不确定性和范数有界不确定性,研究具有状态和控制时滞的不确定线性系统的鲁棒镇定问题·基于Lyapunov泛函,利用线性矩阵不等式给出了系统可由状态反馈鲁棒镇定的充分条件,并且利用线性矩阵不等式的解构造了状态反馈控制律·所得线性矩阵不等式直接保证Lyapunov泛函对时间的导数为负,降低了控制器设计的保守性·最后,给出两个算例说明本文方法的有效性·     

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．     

变时滞不确定性神经网络的鲁棒稳定性标准

研究了一类带变时滞和参数不确定的神经网络鲁棒稳定性问题。其中考虑的不确定性为范数有界不确定性,系统参数具有的这种不确定性是与时间相关的,但它的参数被限制在一定范围内,时间滞后函数是随时间变化而改变的,但它的导数是小于1的。并且通过一个线性矩阵不等式的方法得到一个充要条件,这个充要条件可以使带时滞的神经且有一个平衡点,并且在这个平衡点上具有鲁棒稳定性。这种基于线性矩阵不等式的充分条件可以通过近年发展的解线性矩阵不等式的算法得到数值结果,并通过数值例子说明了这个技术的有效性。     

网络环境下混合时滞系统对时滞参数的自适应控制

在网络环境下,建立了一类复杂的混合时滞系统模型,该模型被控对象为连续系统,控制输入为离散序列且状态时滞参数未知.在分别建立了连续与离散的模型基础上,根据已有的混合系统的稳定性定理,提出了一种镇定系统的方法,并得到了离散形式的可用于控制输入的对未知时滞参数的自适应律.控制方法基于一种Lyapunov-Krasovskii泛函,且在得到的自适应律作用下,对未知时滞参数的估计值能始终被反映在带记忆状态反馈控制器中,且依赖于时滞的反馈控制器,存在的充分条件均可通过一组线性矩阵不等式LMIs表示.     

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.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

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.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Jane Eyre——A Feminist In The 19th Century

In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.     

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-