基于最小方差控制的闭环辨识信号设计

讨论了系统辨识实验信号的设计方法．从实际控制器和理想控制器间误差的角度出发，评价系统性能指标为系统在实际和在理想控制器控制下输出误差的平方均值最小．当输入信号或输出信号能量有限时，分别推导出辨识输入信号功率谱密度．当控制策略为最小方差控制时，给出信号功率谱的具体表达式．结论对在最小方差控制下的闭环辨识信号设计有指导作用．     

多变量系统子子模型辨识

目前,对多变量系统辨识的研究已经越来越多,但是,基本上都属于子模型的辨识问题,不便于实际应用.本文采用子模型与子子模型技术,将一个有R个输入,m个输出的多变量系统分解为M个带R个输入的子模型,而每个子模型又可分解为R个子子模型(单输入单输出系统).在多变量系统中,只要做一次试验(同时加入月个输入信号),使用月个输入信号与M个输出信号的数据,可以自动辨识子模型的阶次与参数,再从子模型的有关数据,最终辨识出子子模型的阶次与参数.本文采用分块矩阵求逆公式,提出一种快速的自动定阶与估计参数的递推算法.     

无人直升机纵、横向姿态建模与稳定控制

在实际飞行中设计调整小型无人直升机控制器存在很多危险,为了达到小型无人直升机的姿态稳定控制,设计小型无人直升机试验平台.通过试验,采集控制器输入信号和相应无人直升机飞行姿态角信号,提出了动态系统辨识模型,运用神经网络对所提模型进行了辨识.应用输出反馈实现姿态的稳定解耦控制,仿真结果验证了辨识模型和控制算法的有效性.     

表面建筑材料吸放湿特性的辅助变量辨识

建立了以材料表面空气相对湿度为输入，材料湿容量为输出的建筑围护结构材料动态湿特性单输入单输出辨识数学模型，得到相应的Z传递 函数模型。建造了建筑围护结构材料的辨识试验系统。采用辅助变量辨识方法辨识得到单输入单输出差分方程和Z传递函数。并比较了最小二乘辨识法和辅助变量辨识法的辨识结果。结果表明，辅助变量辨识法辨识精度有所提高，系统阶降低。     

MIMO液压伺服系统及噪音的时间序列分析

一、引言单输入单输出液压系统的参数辨识问题,在国内、国外都有了一些研究成果。这包括频域参数辨识、伪随机信号相关分析法,这些方法都需要事先人为确定模型的阶。文献给出了单输入单输出液压伺服系统模型阶和参数的时间序列分析方法。在此基础上,本文进一步提出了多变量液压伺服系统的时序辨识方法。该方法可以在对系统一无所     

方波输入信号下随机系统盲辨识方法

在方波输入信号下,通过归一化模型参数或输入信号,提出了随机系统两种盲辨识算法,仿真例子说明提出算法的有效性.     

Hammerstein模型非线性环节折线表示辨识方法研究

以单输入单输出非线性系统Ｈａｍｍｅｒｓｔｅｉｎ模型为对象，研究了一种基于非缄性环节折线近似表示的辨识方法，该法对三位式伪随机序列的构造辨识激励信号，可辨识出非线性静态环节参数和线性动态环节参数的一致估计值。     

基于组合信号的Wiener-Hammerstein系统辨识

针对噪声干扰条件下的Wiener-Hammerstein系统,提出一种基于组合信号的两阶段辨识算法用于辨识Wiener-Hammerstein系统各个环节参数.利用自回归(autoregressive, AR)模型和有限脉冲响应(finite impulse response, FIR)模型分别建立Wiener-Hammerstein系统的输入和输出线性环节,利用多项式模型建立非线性环节.在第一阶段,基于高斯信号的输入和输出,采用相关性分析方法辨识Wiener-Hammerstein系统中输入和输出线性环节的参数,有效解决了中间变量不可测的问题.在第二阶段,基于随机信号的输入和输出数据,利用递推最小二乘法辨识非线性环节参数.仿真结果表明,提出的两阶段方法能够有效辨识Wiener-Hammerstein系统,与其他辨识方法相比,辨识精度有所提高.     

轧机液压AGC系统的相关辩识

本文根据相关原理提出了一种以逆重复伪随机信号为系统输入信号的相关辨识法,该法在轧机液压压下系统中的试验结果表明,它不仅能测得系统的准确动态特性,而且为大型复杂系统的在线辨识提供了一种有效手段。     

过采样方法在系统辨识中的应用

为了对带噪输出的控制系统进行盲辨识，提出了一种利用过采样法辨识控制系统函数的方法，通过过采样控制系统的输出信号，将原单输入单输出系统转换成为一个新的与原系统具有相同输出极点的单输入多输出系统，再估计出这个新的单输入多输出系统的传递函数，最后得到原单输入单输出系统的模型参数，仿真结果表明，与常用的高阶矩法相比，该方法具有不受系统结构影响，不需要计算样本数据的高阶统计矩，使用的样本数据量少，便于计算机实现的优点。     

诗与"在"--海德格尔诗学的阐释

海德格尔对荷尔德林诗歌的阐释，目的是进行诗与思的对话，归根结底还是探讨存在。诗与“在”的关系，是海氏诗学框架的核心内容，诗与“在”的关系又进一步引申为艺术与真理的关系，本从真理如何被遮蔽的问题入手，试图读解海德格尔诗学的内涵。艺术是无蔽的真理显明的一种方式，诗是危机的拯救，语言是存在的家园。海德格尔对诗与在的探讨最后又转入了对语言的探讨，无法走出语言的牢笼。只有在实践中，把艺术变成为社会变革的一个因素，才可以解放被传统理性压迫的力量，显现艺术的真理，确立艺术的价值。     

Regulation of canonical Wnt/β-catenin pathway in the nucleus

Canonical Wnt/β-catenin pathway plays a central role in development, homeostasis, as well as tumorigenesis. The regulation of the pathway involves various and complicated mechanisms, including the extracellular, intracellular and endonuclear regulation. As the key component of the pathway, the Lefl/Tcfs-β-catenin complex is also the key target of regulation in the nucleus. In the current review, we are going to summarize the regulators in the nucleus which can modify the transcrip- tional activity of the Wnt/β-catenin pathway.     

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.     

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-     

论信托财产的人格性

信托财产是信托关系的基本要素,由于信托的特殊性,信托财产与传统民法的财产有很大区别,正确给信托财产定位,是信托业得以健康发展的核心问题。信托财产的特性在于其人格性,而这种人格性的赋予是以交易成本最小化为动因,尽管信托财产人格性设计对受益人的利益有偏袒,但从社会成本而言,其目的在于促使交易成本最小化,当然,对信托财产的人格性不能绝对化,由于利益平衡的需求,往往在特定情况下对信托财产予以人格否认。     

卤素离子在多晶铜电极表面的微分电容研究

本文通过测量金属晶体电极表面的微分电容研究了金属电极表面在金属与水溶液界面上的吸附能力,以及金属与吸附质之间的相互作用。文中论述了多晶铜电极在(0.5-x)mNaClO_4+xmNaBr的一系列不同x值的溶液中的微分电容测量值及微分电容-电位曲线,证明了F~-和ClO_4~-离子在多晶铜电极表面是非常弱的吸附,Br~-离子在多晶铜电极表面具有特定的吸附,每条电容-电位曲线有一个凸起的峰。在峰所对应的位能值,金属表面对阴离子的吸附能力强,证实金属-吸附质之间的相互作用强,吸附的阴离子在过渡层中散射导电电子的能力也强。对于相同阴离子和金属的体系,其微分电容与吸附质的浓度、电压、溶液的pH值和表面的非均匀性等因素密切有关。研究证明,金属晶体电极表面在电解质溶液中的微分电容的变化规律类似于表面电反射信号的强弱变化规律,微分电容大小取决于金属-吸附质之间的电荷转移程度。     

气体对阴离子表活剂压裂液破胶实验研究

阴离子表活剂压裂液是新型清洁压裂液,原油和地层水对其破胶机理与实验研究已相当充分,但气体对其破胶作用至今研究很少.为解决阴离子表活剂压裂液在压裂应用中的障碍,研究采用一套实用的实验流程,评价了天然气、氮气、二氧化碳三种常见气体对阴离子表活剂压裂液的影响.实验证明,三种不同的气体对阴离子表活剂压裂液的降粘幅度存在较大的差别,其中,二氧化碳气体对阴离子清洁压裂液降粘幅度最大,可使交联液体彻底破胶,天然气对阴离子型表活剂压裂液降粘幅度较小,氮气对阴离子压裂液的粘度几乎没有影响,氮气和天然气可以使液体泡沫化,从而有利于返排.实验结果为优化压裂设计提供了依据,可有效提高现场压裂施工成功率.     

多腔速调管主要性能指标简化分析

介绍了速调管在我国的发展现状和几种不同结构的多腔速调管的主要特性比较,并给出了小信号条件下速调管的各种主要特性的简化分析方法.在这种简化分析方法中,把多腔速调管看作是几个双腔速调管的级联,并且没有考虑非线性、空间电荷效应和相对论效应等带来的影响,目的是阐述基本原理和基本分析方法.     

DEM/CFD modelling of the deposition of dilute granular systems in a vertical container

Deposition of granular materials into a container is a general industrial packing process. In this study, the deposition behaviour of dilute granular mixtures consisting of two types of particles that were of the same particle size but different particle densities in the presence of air was numerically analyzed using a coupled discrete element method （DEM） and computational fluid dynamics （CFD）. Bilayer granular mixtures with light particles at bottom and heavy particles at top were first simulated. It was found that the presence of air significantly affected the flow behaviour of the bilayer mixtures. For the system with a relatively low initial void fraction, the air entrapped inside the container escaped through the dilated zones induced due to the friction between the powder bed and wall surfaces. The escaping air streams entrained light particles that were originally located at the bottom of the granular system. Consequently, these light particles were migrated to the top of the granular bed at the end of deposition process. More light particles were migrated when the deposition distance was increased. For the system with a high initial void fraction, some light particles penetrated into the top layer of heavy particles and created a mixing zone. Deposition of random mixtures with different initial void fractions was also investigated and the influence of initial void fraction on the segregation behaviour was explored as well. It was found that the increase of void fraction promoted segregation during the deposition in air. It was demonstrated that, for granular mixtures consisting of particles of different air sensitivities, the presence of air had a significant impact on the mixing and segregation behaviour during the deposition.     

Using new fusion operations to improve trust expressiveness of subjective logic

Subjective logic provides a means to describe the trust relationship of the real world.However,existing fusion operations it offers treat fused opinions equally,which makes it impossible to deal with the weighted opinions effectively.A.Jφsang presents a solution,which combines the discounting operator and the fusion operator to produce the consensus to the problem.In this paper,we prove that this approach is unsuitable to deal with the weighted opinions because it increases the uncertainty of the consensus.To address the problem,we propose two novel fusion operators that are capable of fusing opinions according to the weight of opinion in a fair way,and one of the strengths of them is improving the trust expressiveness of subjective logic.Furthermore,we present the justification on their definitions with the mapping between the evidence space and the opinion space.Comparisons between existing operators and the ones we proposed show the effectiveness of our new fusion operations.