迟滞系统的鲁棒自适应变论域模糊控制

设计了一个H∞变论域模糊控制器,用于控制一类单输入单输出的基于Preisach模型的未知迟滞非线性系统.该控制器将H∞控制与模糊控制结合起来,提高了H∞控制的智能性和模糊控制的鲁棒性.通过Lyapunov方法,证明了闭环控制系统是稳定的.该控制系统中模糊逻辑逼近误差和外部扰动误差都能通过调节权重因子被限定在一个给定范围内.最后,给出了关于未知迟滞非线性系统的仿真结果,表明了控制方案的可行和有效性.     

二次型稳定H∞鲁棒飞行控制

建立飞行／推力数学模型时，总存在着因不确定性而导致建模误差。实际中，有一类不确定性不改变对象模型的动态阶数，并可用参数摄动来描述。本文将二次型稳定性概念应用于飞行／推力控制系统，用H∞控制理论设计的控制系统能很好地解决这类参数不确定的鲁棒控制问题，进行了数字仿真，结果表明H∞飞行控制系统有较好的鲁棒性，能够满足对飞行控制系统的鲁棒稳定性的要求。     

基于反馈线性化的气压伺服系统非线性H∞控制

该文将基于直接反馈线性化的非线性H∞控制策略应用于气压伺服系统。一方面，引入反馈线性化把具有强非线性的气压伺服系统转化为伪线性系统，从而可利用线性系统理论进行控制器设计；另一方面，引入H∞控制，处理由于模型不准确，运行参数的摄动等引起的鲁棒性问题。这使得对于气压伺服系统能够按照一定的性能指标来设计控制器，并且该控制器对于系统运行参数摄动和建模不准确具有鲁棒性。     

基于参数摄动的电动汽车再生制动鲁棒混合控制研究

针对电动汽车再生制动过程中系统具有参数大范围摄动和强非线性的特点,综合H2最优控制和H∞鲁棒控制的优点,提出鲁棒H2/H∞混合控制策略.将系统主回路参数摄动到控制输入灵敏度函数的H∞范数作为鲁棒性能评价指标,电动汽车外加扰动到电机转速传递函数的H2范数作为线性高斯二次型性能指标.仿真和对比实验结果表明,鲁棒H2/H∞混合控制策略具有良好的控制效果,比传统的控制方法回收了更多的能量,同时抑制了系统参数大范围摄动、强非线性以及外界干扰的影响,从而大大提高了系统的鲁棒稳定性.     

H∞优化控制理论在振动控制系统中的仿真研究

研究了H∞优化控制方法在振动控制系统中的应用.以磁悬浮球装置作为被控对象,研究了H∞优化控制在抗干扰能力、鲁棒性,以及抑制"溢振”方面的性能.仿真结果表明H∞优化控制理论在振动控制中抑制"溢振”方面具有优良性能.     

非线性离散时滞系统的非脆弱H_∞保成本容错控制

基于Lyapunov稳定性理论,研究一类不确定非线性离散时滞系统的非脆弱H∞保成本容错控制问题.在考虑执行器故障和控制器参数存在加法摄动的情况下,利用线性矩阵不等式方法,给出了非脆弱H∞保成本容错控制律的存在条件、非脆弱H∞保成本控制器的设计方法和控制器的清晰的表达形式.最后通过一个仿真算例,验证了本文提出算法的有效性.     

基于自适应神经网络的歼击机模糊跟踪控制

提出了一种基于T-S模糊模型和自适应神经网络的跟踪控制方法.在系统具有未知不确定非线性特性的情况下,利用T-S模糊模型对系统的已知特性进行近似建模,设计基于模糊模型的模糊H∞跟踪控制律进行输出跟踪控制.在模糊控制的基础上,引入了基于RBF神经网络的自适应控制,用于在线对消不确定项和模糊建模误差的影响,以保证系统具有期望的鲁棒H∞跟踪性能.所提出的方案保证了闭环系统的稳定性,有效地提高了系统的鲁棒性和跟踪性能.仿真实例表明了所提出方法的有效性.     

H_∞优化控制理论在振动控制系统中的仿真研究

研究了H∞优化控制方法在振动控制系统中的应用。以磁悬浮球装置作为被控对象,研究了H∞优化控制在抗干扰能力、鲁棒性,以及抑制“溢振”方面的性能。仿真结果表明H∞优化控制理论在振动控制中抑制“溢振”方面具有优良性能。     

多时滞不确定系统的非脆弱H∞鲁棒控制

针对一类复杂的多时滞不确定系统,在控制器增益存在加性和乘性两种摄动形式时,分别设计了非脆弱H∞鲁棒控制器,利用构造的Lyapunov函数和线性矩阵不等式,证明并给出了非脆弱H∞鲁棒控制问题有解的充分条件.所设计的控制器使系统具有鲁棒性,能满足所给H∞范数指标,而且当控制器增益参数变化时,系统性能指标同样能够满足要求.该系统对环境参数的变化具有更好的适应能力.算例仿真结果表明,系统对不确定参数变化及控制器增益摄动都具有鲁棒性,对大幅度的干扰波动具有很强的抗扰动能力.     

交流转矩伺服系统H∞鲁棒控制

以交流转矩伺服系统简化模型为控制对象,设计了基于H∞鲁棒稳定控制器的两自由度内模控制器.仿真实验结果表明,在系统参数存在摄动的情况下,与传统控制器相比系统跟随性能、鲁棒稳定性均有所提高,有效抑制了参数摄动对系统性能的影响.     

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.     

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.     

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.     

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.     

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.     

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.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

A computer generator for randomly layered structures

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

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.