一类混沌系统的混合参数自适应学习控制

提出了一种自适应学习控制方法,应用于未知周期时变参数的混沌系统的跟踪同步问题,该方法利用Lyapunov稳定性和自适应学习理论,构造了学习控制律和微分-差分参数学习律,在L2Τ-范数意义下使得跟踪误差在一个周期区间上渐近同步。给出了闭环系统稳定的一个充分条件。通过仿真例子验证了所提方案的可行性和有效性.     

不确定机械臂的组合自适应迭代学习轨迹跟踪

针对一类同时含未知时变和未知定常参数、并带有可重复时变干扰的不确定机械臂系统,为精确跟踪期望轨迹并加快跟踪误差的收敛速度,提出了一种具有抗扰能力的机械臂组合自适应迭代学习控制算法.对未知定常参数和未知时变参数,分别采用时域和迭代域的参数自适应迭代学习律,并基于估计参数设计了机械臂的自适应迭代学习轨迹跟踪控制律.利用相似李亚普诺夫函数证明了轨迹跟踪误差的收敛性.针对二自由度关节式机械臂的仿真结果表明,应用所提算法可实现精确的轨迹跟踪,并加快迭代学习的收敛速度.     

含有时变延迟的双线性参数化系统的重复学习控制

针对一类含有时变延迟的双线性参数化时变系统,提出了一种新的重复学习控制方案.该方案假设未知时变参数、未知时滞和参考信号的共同周期是已知的,通过重构系统方程,有效地消除时变延迟的影响,采用微分—差分耦合参数周期自适应律估计时变和时不变参数,可以处理参数在一个未知紧集内周期性快时变的非线性系统,通过构造一个Lyapunov-Krasovskii能量函数,证明所有信号有界并且跟踪误差渐近收敛.给出了闭环系统收敛的一个充分条件.仿真结果验证了控制算法的有效性.     

低信噪比下的变步长最小均方自适应算法及其在时延估计中的应用

为提高变步长最小均方(LMS)自适应算法在噪声干扰下的时变时延跟踪性能,提出改进的变步长LMS自适应算法.该算法对MVSS-LMS算法进行误差均值补偿,改步长因子固定范围约束为动态变化约束;使用HB加权突出自适应滤波器权系数峰值,采用滑动窗遗忘加权减小计算复杂度.自适应时延估计仿真实验和消声水池目标被动定位试验表明:相比于参数固定条件下的MVSS-LMS算法和SVS-LMS算法,改进算法能够获得更好的时变时延跟踪性能.     

基于滑模控制分数阶统一混沌系统的函数投影同步

研究分数阶统一混沌系统的混沌特性.基于滑模控制理论设计了一种自适应函数投影同步的控制方案.选取合适的控制器以及自适应控制律,证明分数阶误差系统为渐近稳定的,驱动-响应系统最终实现自适应修正函数投影同步,且可以对驱动系统的不确定参数进行估计.最后利用Adams-Bashforth-Moultom算法进行数值仿真,仿真结果表明该方法是有效可行的.     

含有未知参数的广义Lorenz系统的自适应投影同步

研究了含有未知参数的广义Lorenz系统的自适应投影同步问题.对于参数完全未知的情形,提出了4种控制器设计策略,实现了两个广义Lorenz系统间的自适应投影同步,对于响应系统参数未知的情形,通过本文设计的控制器,可以实现广义Lorenz系统中两个拓扑不等价的系统之间的同步,同时未知参数可以被识别.数值仿真结果说明了方法的有效性.     

带有死区修正的非线性系统L2控制器设计

针对具有未知参数的受扰非线性系统,提出了一种带有死区修正的自适应鲁棒L2设计方法.根据参数的先验信息,通过将光滑投影算法、死区修正技术与参数自适应律结合起来,既抑制了参数的漂移、减小了计算负担,又使估计参数达到了最小.当外界干扰为零时,算法能够保证跟踪误差渐近收敛于任意设定的死区.当外界干扰不等于零时,系统满足L2干扰抑制性能指标.仿真结果进一步说明了算法的有效性.     

多输入多输出非线性时变时延系统的自适应跟踪控制

针对多输入多输出非线性时变时延系统,提出了一种模糊自适应跟踪控制方案,该方案构建了基于模糊T-S模型的自适应时变时延模糊逻辑系统,用来逼近未知非线性时变时延函数,从而实现了对非线性系统的建模.根据跟踪误差给出了模糊逻辑系统的参数自适应律,设计了H..补偿器来抵消模糊逼近误差和外部扰动.基于Lyapunov稳定性理论,提出的控制方案保证了闭环系统的稳定性并获得了期望的H..跟踪性能,机械臂的仿真结果表明了该方案的有效性.     

一类欧拉-拉格朗日系统的自适应切换跟踪控制

研究一类具有周期扰动的欧拉-拉格朗日系统的自适应切换跟踪控制问题.与相关文献本质不同的是,扰动具有未知周期和上界,导致传统的控制方法无效.首先,利用反推设计方法并结合扰动学习机制,给出状态反馈控制器(含有待调节的控制器参数)的显式形式.然后,设计适当的切换机制在线调节控制器参数.切换发生有限次之后停止,所设计的自适应切换控制器保证闭环系统所有状态都有界并且系统输出跟踪到给定的参考信号.最后,仿真实验验证理论结果的有效性.     

超混沌Lü系统的自适应广义投影同步

基于自适应控制方法和Lyapunov稳定性理论,分别在参数完全未知和部分未知的情况下,设计适合超混沌Lü系统广义投影同步的非线性自适应控制器,并进行数值仿真.结果表明,该方法使2个恒同超混沌Lü系统在全局范围内实现广义投影同步,在部分参数未知的情况下,实现了参数的跟踪.     

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.     

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.     

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     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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