多变量无模型预测神经网络线性自抗扰控制

对难以建模的多变量非线性系统的控制难题,提出改进的具有辅助向量的多变量全格式动态线性化方法,采用其逼近非线性系统,用其构成预测模型,将其转化为具有耦合的若干个子系统,利用直接极小化指标函数自适应优化算法辨识其参数,将多变量线性扩张观测器的线性控制输入项改进为关于观测状态和控制输入向量及其微分的向量函数,并由该向量函数的逆向量函数构建当前控制输入向量,因其未知,使用对角回归神经网络逼近控制输入向量函数,采用多变量非线性递推最小二乘法优化对角回归神经网络连接权及多变量线性自抗扰控制参数,综上研究提出在线优化参数的多变量无模型预测神经网络线性自抗扰控制算法。仿真研究表明系统响应精度高,性能好,优于传统的线性自抗扰控制算法。     

隧道围岩变形的非线性自回归时间序列预测方法研究

针对传统时间序列预测模型的单一线性和忽略施工过程影响的静态局限性,提出非线性自回归(包括NARNN与NARXNN)时间序列预测模型.该模型通过引入动态施工影响因子作为附加的外部输入,同时结合模型本身的反馈结构和延迟单元,在结构和动态特性上更加符合实际系统,可以非线性动态地考虑隧道施工全过程.运用该模型对史家山2号隧道施工过程中的围岩水平收敛和地表变形进行预测.结果表明:1)非线性自回归预测模型比传统的ARMA预测模型的预测精度高、适应性好;2)通过多次预测并对结果取平均值,可以保证非线性自回归预测模型预测结果的预测精度和稳健性;3)通过优化动态施工影响因子的取值方法,可以进一步提高NARXNN时间序列预测模型的预测精度.     

多层局部回归网络的非线性系统预测模型

提出采用多层局部回归神经网络建立多变量非线性系统多步预测模型的方法,神经 网络模型可提供多步预测控制所需要的系统输出预测值及输出向量对控制向量的雅可比矩 阵．仿真试验表明这种动态神经网络的预测模型具有较高的精度．     

基于神经网络的永磁同步电机广义预测控制

介绍了一种基于神经网络的永磁同步电机矢量控制系统的广义预测控制方法.通过分析永磁同步电机数学模型,采用带有延时结构的多层前向神经网络作为预测模型,进行非线性广义预测控制.控制算法是基于非线性激励函数的局部线性思想,将预测模型处理成线性和非线性两部分,并用线性预测控制方法求得控制律,简化了计算.仿真结果表明,利用该法建立的永磁同步电机调速系统,具有良好的控制效果.     

基于线性函数型权重的RBF-ARX模型的磁悬浮球系统预测控制

为了充分描述磁悬浮球系统具有非线性、开环不稳定性及响应快速性等特性,建立一个带线性函数权重的RBF-ARX(linear functional weight RBF networks-based ARX model,LFWRBF-ARX)模型。与一般的RBF-ARX模型不同之处在于,它引入1个与工作点状态相关的局部线性结构作为RBF网络输出层的权值。该模型随系统工作点的变化而变化,固定工作点时为局部线性ARX模型,当工作点变化时为全局非线性ARX模型。根据该模型的结构特点,采用结构化非线性参数优化方法(structured nonlinear parameter optimization method,SNPOM)来辨识模型的结构及线性、非线性参数。然后,以辨识的模型为基础,根据模型的局部线性及全局非线性特征设计预测控制器。仿真结果表明:以该建模方法建立的模型能很好地局部和全局描述磁悬浮球系统的动态特性,并能实现小球的稳定悬浮控制,比以一般ARX模型、RBF-ARX模型为基础的控制效果更好。     

微燃机-冷热电联供机组的Hammerstein模型及非线性广义预测控制

为研究微燃机-冷热电(MGT-CCHP)联供机组动态运行特性及控制策略,采用Hammerstein模型结构快速辨识其非线性动态特性,并将非线性动态特性以串联的非线性静态模型和线性动态模型表示.采用逐步回归法确定动态模型阶次并采用粒子群算法辨识模型参数,得到易于复现的块结构化模型.基于Hammerstein预测模型,设计了MGT-CCHR冷负荷跟踪非线性广义预测控制器.利用Hammerstein模型分块描述对象静态与动态特性的结构特点,将非线性广义预测控制转化为线性广义预测控制与非线性静态函数求根问题,使控制量求解简化.通过与最优参数PID控制器的仿真结果比较表明,所设计的非线性广义预测控制器具有改善冷负荷跟踪性能和节能控制的效果.     

PMSM的基于神经网络非线性预测控制

采用三层前向神经网络作为PMSM转速预测模型,对PMSM进行非线性预测控制.先通过离线训练获得初始预测模型,再在线对神经网络模型的权值和阀值进行调整;控制算法是将预测模型处理成线性和非线性两部分,并用一种快速线性预测控制方法求取控制律,大大减小在线计算量和提高控制的实时性.最后仿真结果表明该方法具有良好的动、静态特性和抗干扰能力.     

一种基于RBF神经网络预测模型的DMC预测控制

研究了一种利用RBF神经网络预测模型的动态矩阵控制算法,首先利用动态节点生成构造性RBF神经网络辨识对象模型,同时预测对象的未来输出,然后用传统的动态矩阵控制算法进行滚动优化和反馈校正。仿真表明该算法在非线性对象的任意工作点都可以通过神经网络辨识获得工作点附近的近似线性模型,具有较好的实时性。     

RBF神经网络优化灰线性回归模型预测建模

针对建筑物地基沉降的机理以及RBF(Radial Basis Function,径向基函数)神经网络能够有效描述不确定性问题和解决复杂非线性问题等特点,通过反复试验,优化设计,建立了RBF神经网络,并用该网络优化灰线性回归预测模型,建立RBF灰线性组合预测模型。通过工程实例,比较分析了单一灰色模型、灰线性回归模型、RBF优化的灰线性回归模型的预测精度。结果表明,RBF优化后的灰线性回归预测模型精度优于灰色模型、灰线性回归模型,预测中误差达到0.0014 mm。径向基神经网络优化后的灰线性模型能更好地反映建筑物沉降的总体趋势及规律。     

紧格式无模型自适应控制在直线电机中的仿真

将基于紧格式线性化的非线性系统无模型自适应控制方法应用于直线电机的运动控制中.用紧格式动态线性时变模型替代直线电机非线性系统模型,根据直线电机运动模型的输入输出数据在线估计系统的伪偏导数.仿真实验表明,紧格式无模型自适应控制方法对电机这种具有不确定动态的非线性系统有较强的自适应性、抗干扰性、稳定性和鲁棒性.     

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.     

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     

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