基于干扰观测器的二元机翼颤振抑制及阵风载荷减缓方法研究

针对大展弦比柔性飞机在飞行过程中面临的两类气动弹性问题:颤振抑制与阵风载荷减缓开展研究。首先,建立以飞行速度为时变参数的柔性二元机翼结构动力学模型。其次,提出了基于鲁棒预测控制方法的变参数柔性机翼颤振抑制;同时,引入干扰观测器对阵风扰动进行观测,以干扰估计作为抗干扰控制输入,实现阵风载荷减缓。然后,根据对偶原理,将控制器与观测器独立设计。运用极点配置方法,设计了离散系统干扰观测器。根据Lyapunov理论将变参数系统的鲁棒镇定与颤振抑制问题转换为极大/极小动态规划问题。通过线性矩阵不等式方法求解出相应的预测控制律,并证明了整个闭环系统的稳定性。最后,以某型柔性变参数二元机翼对象为例,进行仿真。结果表明,设计的鲁棒预测控制器可提高约20%的临界颤振速度,且阵风载荷减缓率达到90%。     

不确定非线性系统的鲁棒H_∞保性能控制

针对具有有界时变参数不确定性和外部干扰的非线性系统,提出了一种鲁棒H∞保性能控制设计方法.基于李雅普诺夫稳定性定理和多项式平方和(sum of squares,SOS)方法,直接对非线性模型采用非线性的控制方法,给出基于状态反馈的鲁棒H∞保性能控制器存在的充分条件,使得闭环系统对于所有可能的不确定性和外部干扰不仅能够鲁棒渐近稳定,同时还能够满足相应的二次性能指标和H∞性能指标.通过求解相应的凸优化问题,得到状态反馈控制器,使得二次型性能指标上界或H∞干扰抑制度最小.仿真结果验证了所提方法的有效性.     

非线性不确定性奇异系统的鲁棒H∞控制

讨论了非线性不确定性奇异系统的鲁棒H∞控制问题，给出了非线性不确定性奇异系统的H∞鲁棒性能准则，利用经性矩阵不等式（LMIs)的方法，给出了系统满足H∞鲁棒性能准则的充分条件，在这个条件下，分别讨论了非线性不确定性奇异系统的鲁棒H∞控制反馈控制器和输出反馈控制器的设计，得到了鲁棒H∞控制器存在的充分条件。     

基于H_∞理论的倒单摆控制系统

利用loop shaping design procedure(LSDP)设计倒单摆H∞控制器,以Tustin摩擦力模型及干扰观测器(disturbance observer,DOB)补偿台车与轨道间的摩擦力及干扰,观察在H∞控制器下倒单摆的鲁棒稳定性及鲁棒性能.实验结果显示,补偿摩擦力及干扰后的系统明显优于未补偿的系统.     

汽车四轮转向系统的H∞控制

为了使不确定性输入对受控输出的影响降低到最小,提高系统的鲁棒性能,以汽车四轮转向二自由度模型为基础,针对外界干扰,采用H∞性能指标进行评价,建立汽车四轮转向H∞控制系统.运用H∞控制理论的分析方法,采用前馈和反馈的组合控制进行了最优控制设计.仿真结果表明,设计出来的H∞控制器能够很好地抑制外界干扰对系统稳定性的影响,并且达到了预先控制目标,有效地提高了汽车四轮转向的鲁棒性能.     

电动汽车电动助力转向系统鲁棒H∞控制

针对汽车行驶过程中汽车EPS控制器受到转向系统参数摄动、路面干扰、传感器噪声以及大侧向风干扰等不确定性影响,导致助力电流的不精确性和影响EPS系统性能和驾驶安全的问题。建立了EPS系统数学模型,分析了EPS系统的内部不确定性以及外部干扰。用LFT线性分式变换形式表达出EPS模型,求解了不确定性M矩阵。应用H∞控制理论,根据系统性能指标设计了权函数和H∞控制器。结果表明,与PD控制进行了性能对比,稳定时间和电动机最大助力扭矩分别降低了40.00%和36.98%。在传感器噪声和路面高频力矩等外界干扰影响下,H∞控制器比PD控制器具有更好的性能鲁棒性和鲁棒稳定性,具有良好的抗干扰性能,能够满足EPS性能要求。     

一类模糊不确定网络控制系统的保性能控制

针对网络控制系统中存在数据传输时延,以及由被控对象和控制器之间的不同步给系统所带来的稳定性问题,提出了鲁棒H∞保性能控制器的设计方案.将时延的不确定性转换为系数矩阵的不确定性,在此模型基础上利用并行分配补偿,并根据H∞鲁棒控制理论及线性矩阵不等式(LMI)方法,获得了网络控制系统的全局渐近稳定性及H∞控制律存在的充分条件,同时提出了网络控制系统鲁棒H∞保性能控制器的设计方法,仿真说明该方法的可行性和有效性.     

基于H∞理论的倒单摆控制系统

利用loop shaping design procedure（LSDP）设计倒单摆H∞控制器,以Tustin摩擦力模型及干扰观测器（disturbance observer,DOB）补偿台车与轨道间的摩擦力及干扰,观察在H∞控制器下倒单摆的鲁棒稳定性及鲁棒性能．实验结果显示,补偿摩擦力及干扰后的系统明显优于未补偿的系统．     

一类不确定性系统鲁棒H∞控制器的设计

讨论了一类同时具有匹配不确定性和不匹配不确定性系统鲁棒H∞控制问题.对于所有容许的不确定性,基于矩阵不等式给出了二次稳定的条件并对系统的H∞性能进行了分析和设计;给出了系统的鲁棒H∞控制器,该控制器不仅满足系统二次稳定的条件,而且也满足H∞性能约束条件.数值算例说明了控制器设计方法的有效性和可行性.     

一类不确定切换系统的鲁棒H∞动态输出反馈控制器设计

研究了一类具有未知时变但有界的结构不确定性和输入通道不确定性的切换系统的鲁棒H∞动态输出反馈控制器设计问题.利用完备性条件和共同李亚谱诺夫函数方法,设计了相应子系统的H∞动态输出反馈控制器和相应的切换策略,得到了切换系统动态输出反馈鲁棒H∞控制器存在的充分条件.采用变量替代法,将非线性矩阵不等式转化为一组易于求解的线性矩阵不等式(LMIs).最后通过仿真例子表明系统在所设计的H∞控制器作用下得到的闭环系统,在相应的切换策略下,满足鲁棒H∞性能.     

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-