基于Backstepping设计的非线性鲁棒自适应控制

针对一类具有未知参数,未建模动态和外界干扰的不确定非线性系统,选择适当的参数对这些不确定性进行估值和补偿,利用Backstepping方法,设计了一种新的鲁棒自适应控制器.该控制器能保证闭环系统的所有信号是全局有界的,且输出的绝对值可以任意小.仿真结果表明,所设计的鲁棒控制器达到了理想的结果.     

电液伺服系统多模型鲁棒自适应控制

针对电液伺服系统中存在不确定非线性和强参数不确定性的问题,提出一种多模型鲁棒自适应控制算法。根据系统参数不确定性范围建立了多个辨识模型,在辨识模型中设计非线性鲁棒项,以抑制干扰、未建模动态等不确定非线性的影响,提高系统的鲁棒性。基于辨识模型设计相应的控制器,采用基于辨识误差的性能指标函数作为切换依据,选取最佳控制器作为当前控制器,解决了传统自适应控制对参数自适应初值敏感的问题。该方法能够克服不确定非线性和强参数不确定性的影响,使系统得到渐进跟踪的性能,提高系统的瞬态响应性能。实验结果表明,该算法能抑制建模不确定性的影响,系统期望跟踪指令幅值为10mm时,跟踪误差大约为0.038 6mm,相对跟踪误差约为0.386%,系统跟踪精度得到了提高。     

基于主-辅控制架构的无人机鲁棒飞行控制律设计

无人机在实际飞行中易受到扰动与系统未建模动态等不确定性因素的影响.为此,文中提出了一种新的鲁棒飞行控制律设计方法.该方法以主-辅控制器为基本架构,主控制器采用鲁棒伺服线性二次型调节(LQR)法构造,以提供基本指令跟踪控制输入;以加入主控制器后的理想闭环系统为参考模型,基于鲁棒模型参考自适应算法设计辅控制器,以抑制扰动和未建模动态对飞行控制系统的影响.理论分析表明,该控制律能够保证闭环飞行控制系统在存在有界扰动与未建模动态情况下稳定且跟踪误差有界.非线性对比仿真验证了控制系统对各种形式扰动的抑制作用,说明了该控制系统的有效性与鲁棒性.     

具有降阶模型的多模型鲁棒自适应控制

针对传统鲁棒自适应控制器暂态性能差的缺点,提出了多模型鲁棒自适应控制方法.对于包含未建模动态的自适应控制系统,首先采用正则化技术把系统未建模动态转化为系统有界扰动,并利用系统低阶模型设计多模型鲁棒自适应控制器,最后证明了系统BIBO稳定以及跟踪误差有界.仿真实验说明所提出的方法能获得较好的控制效果.     

一类不确定非线性系统的鲁棒自适应控制

针对一类包括非线性不确定性、有界干扰、时变参数等的具有纯参数反馈形式的不确定非线性单输入单输出系统,利用反演设计方法同自适应控制相结合的方法,设计了状态反馈鲁棒自适应控制器.该控制器能使系统达到渐进稳定,并能保证闭环系统信号的全局有界性,对非线性不确定性和有界干扰具有一定的鲁棒性,且对不确定性的知识要求不多.从仿真实例看出,所设计的鲁棒自适应控制器具有满意的控制效果,而且控制量在容许控制的范围之内.     

不确定非线性系统的鲁棒自适应控制

针对一类具有一般不确定性的非线性系统（包括非线性不确定性、有界干扰、时变参数等）,利用递推设计方法,设计了一种新的用于输出调节的鲁棒自适应控制器．该控制器对非线性不确定性和有界干扰具有鲁棒性,并能保证闭环系统信号的全局有界性．其优点是对不确定性的知识要求较少．仿真实例表明,设计的鲁棒自适应控制器具有满意的控制效果．     

带参数辨识的H-∞鲁棒控制方法

从控制方法的实用性出发,综合鲁棒控制和自适应控制方法,处理存在各种非结构不确定性及参数不确定性的线性对象。运用状态空间 Ｈ∞方法设计鲁棒控制器,抑制外部干扰,未建模动态及参数误差。进而引入鲁棒辨识器以确定对象的标称参数,减小鲁棒控制的保守性。并证明了闭环系统的稳定性和鲁棒性。结合 Ｒｏｈｒｓ 反例,验证了算法有效性。该方法实现了自适应律与控制方法的分离,从而避免了传统‘确定性等价原理’带来的系统分析和实际应用的复杂性。     

一类非线性不确定系统的鲁棒镇定

由于实际中的一类非线性不确定系统可以建模为具有状态矩阵和输入矩阵不确定性并受非线性摄动的线性系统,将这类系统的鲁棒镇定问题转化为求解一个线性系统的H∞状态反馈控制问题。结果表明:若该H∞状态反馈控制问题有解,则原系统可以通过状态反馈实现鲁棒镇定。给出了状态反馈矩阵,还进一步给出了具体的仿真实例。仿真结果表明:该理论是可行的,且控制器实现了对这类非线性不确定系统的鲁棒镇定。     

一类具有一般不确定性非线性系统的ε-跟踪 I:输出反馈鲁棒自适应控制系统的设计

该文考虑一类具有一般不确定性和参数未知的非线性系统，首先设计出一个稳定的状态滤波器，从而获得状态的实时估计，然后依此设计出一种用于跟踪参考信号的输出反馈鲁棒自适应控制器。仿真结果表明，所设计的鲁棒自适应控制系统具有良好的跟踪性能，可以有效地解决ε－跟踪问题。     

含TCSC装置的单机无穷大电力系统的非线性自适应动态面鲁棒控制

针对含晶闸管控制串联电容器装置的单机无穷大电力系统,考虑摩擦阻尼系数不确定及受外部未知干扰的情况,基于非线性自适应动态面控制方法,设计了鲁棒控制器,同时得到了系统不确定参数的自适应更新律以及系统稳定运行的充分条件.采用该方法避免了传统自适应backstepping法中对虚拟控制输入的反复求导,克服了计算量过大的缺点.数值仿真结果表明,所设计TCSC非线性自适应动态面鲁棒控制器在系统动态响应和不确定参数的估计性能方面优于传统的自适应backstepping鲁棒控制器,提高了电力系统的动态稳定性.     

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