具有线性前馈环节的高阶系统跟随低阶模型的MRACS设计方法

以往的ＭＲＡＣＳ设计方法都存在的正反馈环,且属同阶跟随同阶的情况．正反馈环的使用往往存在会使系统不稳定的特点,本文用线性前馈环节取代了正反馈环,解决了稳定问题,提高了抗噪声能力,并把原来同阶系统跟随同阶模型的方法,推广为高阶系统跟随低价模型的ＭＲＡＣＳ设计。     

延时正反馈结构及其动力学行为

从各种复杂系统中,抽象出了具有一般意义的延时正反馈结构,建立了该结构的离散动力学模型,并对其不动点的稳定性和分支行为进行了讨论.     

股指期货对股票市场正反馈交易的影响——基于中国A股市场的计量检验

利用非对称GARCH模型和正反馈交易模型，对中国A股市场的正反馈交易进行了计量检验.结果表明:股指期货推出后，股票现货市场的正反馈交易减弱，但正反馈交易减弱的原因并不在于市场信息效率的提升，而是由于正反馈交易由股票现货市场转移至股指期货市场.股指期货对股票市场的正反馈交易主要起到的是分流而非抑制作用，这一结论不同于以往对股指期货作用的乐观评价.计量检验同时发现:投资者风险厌恶程度与正反馈交易强度负相关.正反馈交易具有显著的风险寻求偏好，因此，对股指期货的交易限制，虽然可以短期降低正反馈交易的风险联动，但无法改变正反馈交易的风险偏好.所以，相关的制度安排应重点关注市场效率的提升而非波动抑制.     

基于TL494的PWM等速送丝电路的设计

通过对电压负反馈配合电流正反馈的送丝调速系统与转速负反馈调速系统的比较,得出了这两种调速系统的等效条件,设计了一种基于TL494芯片的电压负反馈配合电流正反馈的CO2焊机送丝调速电路,该电路通过PWM脉宽调制,实现转速的均匀调节,并具有过电流截止保护功能．通过实验,验证了该调速电路的可靠性,实验中,当电源电压由342V变到418V,负载从25N变到50N时,送丝速度的变化率小于5％,符合JB／T9533-1999专业标准要求。     

梅雨锋致洪暴雨的β中尺度涡旋机理的分析

利用模式高分辩率资料，对β中尺度涡旋系统发生和发展的机理进行探讨，发现在湿中性条件下，中尺度气旋得到强烈发展是物理量的中尺度输送和集中及局地区域产生急剧陡峭的上升运动有关。用辐散风动能转换函数诊断分析了暴雨不同时期β中尺度涡旋系统发展的能量来源，得出能量转换与涡散场相互作用的物理图像。这种能量转换增强与涡散场发展相互促进的正反馈过程是系统发展增强的主要因素，同时使得强烈上升运动不致很快消失，是暴雨生命史维持10h的可能原因。     

小容量有静差调速系统在磨床工件旋转中的应用分析

对转速负反馈的单闭环有静差调速系统,可采用一些简化或者改进的措施。对调速指标要求不高的系统,可以用电压负反馈代替转速负反馈,从而省掉测速发电机。电压负反馈系统实质上只是自动调压系统,无法克服电压负反馈以外的扰动作用。在单闭环有静差调速系统中引入电流正反馈,实现扰动量的补偿控制,可以提高静特性的硬度,减少静差,对提高调速系统的静态性能是有益的。     

人体生理活动的正反馈调节

对人体生理活动的调节有两大系统即神经系统与内分泌系统,两大系统的调节机理都存在反馈调节.在正常的生理活动中,为人们所熟知的是多数的负反馈调节活动,而正反馈调节活动则相对较少,人们也较生疏.这篇文章介绍几种常见的生理活动的正反馈调节.     

微机控制的无位置传感器无刷直流电机驱动系统

详细介绍了无位置传感器无刷直流电机的微机控制系统，永磁转子的位置检测是通过检测定子绕组的三相端电压来实现的，起动时让电机按照他控式同步电动机方式运行，实现了无刷直流电机在开环控制、转速负反馈控制，电压负反馈加电流正反馈控制３种方式下的运行。     

军用车辆悬挂系统热-机耦合特性研究

为解决军用车辆悬挂系统中减振器温升过高而漏油失效的问题,提出了全面的车辆悬挂系统机械动力学与其热学特性相互耦合模型.采用Matlab/Simulink建立此闭环正反馈系统的热机耦合模型,仿真计算得到某军用车辆在多种工况以及不同悬挂参数条件下的减振器温升特性曲线.研究结果表明:随着路面等级的下降,车速的提高,簧下质量和负重轮刚度的增大,减振器的温度升高加快;簧上质量和悬挂刚度对减振器温升特性无影响.     

梅雨锋致洪暴雨的β中尺度涡旋机理的分析

利用模式高分辨率资料,对β中尺度涡旋系统发生和发展的机理进行探讨,发现在湿中性条件下,中尺度气旋得到强烈发展是与物理量的中尺度输送和集中及局地区域产生急剧陡峭的上升运动有关.用辐散风动能转换函数诊断分析了暴雨不同时期β中尺度涡旋系统发展的能量来源,得出能量转换与涡散场相互作用的物理图像.这种能量转换增强与涡散场发展相互促进的正反馈过程是系统发展增强的主要因素,同时使得强烈上升运动不致很快消失,是暴雨生命史维持10 h的可能原因.     

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.     

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