分布参数系统参数辨识的最佳测量位置

许多有关集中参数系统参数辨识的方法经改造后可推广到分布参数系统中,但其涉及的问题复杂,其中传感器的测量位置则是分布参数系统参数辨识过程的特有问题,它对分布参数系统的参数辨识精度有着很大的影响.从受噪声干扰的不同位置传感器检测值出发,构造了分布参数系统的信息矩阵,提出了一种基于信息矩阵行列式的优化算法,并采用D-最优试验设计准则优化传感器的位置配置,得到了分布参数系统检测传感器的最佳测量位置,同时保证了系统的参数辨识精度.仿真结果表明,该方法对于分布参数系统的输出和状态检测传感器位置的选择具有参考价值.     

双目立体视觉传感器结构参数优化设计

采用最优回归设计311-A方案设计实验,研究双目立体视觉传感器的结构参数对传感器测量精度的影响.根据实验结果,建立了双目立体视觉传感器的测量精度与传感器结构参数间的回归方程,并通过对优化模型的求解,得到了使双目立体视觉传感器测量精度更高的参数组合.结果表明,利用上述方法可以有效地提高双目立体视觉传感器的测量精度.     

一种新结构自抗扰控制在电液伺服系统中的应用

提出了一种基于零点可调的线性自抗扰控制器结构.在不影响系统稳定性的前提下,调节控制器的零点参数改变系统的响应速度;改变了不确定扰动的补偿方式,消去线性组合补偿(LFC)与扩张状态观测器(ESO)的参数耦合.通过经典控制理论和波特图分析了该控制器时域和频域特性,给出调节零点参数的取值范围;分析噪声对扩张状态观测器的影响,提出了ESO参数选取的条件.通过电液伺服系统跟踪给定曲线实验,表明调节零点参数可以有效加快系统响应,使参数整定更容易.     

广义系统输出反馈镇定与零点配置

研究了线性时不变广义系统的输出反馈镇定与零点配置问题。首先从状态空间角度出发,利用双互质分解方法得到输出反馈镇定控制器的参数化形式。然后从频域角度,在保证广义闭环系统容许的条件下,研究闭环系统的零点配置问题,给出了系统具有不同零点的配置方法。最后通过数值算例证明了所提方法的有效性。     

一种弹体滚转姿态估计的新方法

针对制导弹药滚转姿态测量的需求,提出了一种无陀螺姿态测量的方法. 采用两个MEMS加速度计进行弹上姿态传感器的配置,建立了基于截断正态概率密度模型的系统状态方程,利用速度估计自适应方法实现了对过程噪声方差阵的自适应调整,采用强跟踪滤波器(STF)直接进行滚转状态估计. 由于STF滤波器具有对模型参数失配的鲁棒性以及对突变状态的强跟踪能力,改善了算法的估计精度. 仿真实验研究表明:该方法结构简单、测量精度高、收敛速度快,具有很高的工程应用价值.      

基于反馈调节器的应变式位移传感器非线性校正

因受自身材质、工艺等条件的限制以及温度等外界环境影响,应变式位移传感器的输入-输出特性存在非线性误差.采用最小二乘法建立传感器正模型、逆模型及传统方法补偿后的传感器输出误差模型.在此基础上根据反馈控制理论引入反馈调节器,利用传感器正模型与输出误差模型对系统非线性特性做进一步补偿,实现对传统非线性校正方法的改进.同时,通过调节反馈系数改变反馈调节器的作用强度,可抑制系统零点漂移.研究结果表明,经含有反馈调节器的非线性校正环节作用后,系统的非线性特性及零点漂移得以改善     

激光三维加速度传感器的结构设计

目前的研究及工程场合对三维加速度的测量提出更高要求,针对于此提出了一种新型加速度光纤传感器的设计,它以弹性平膜片与角锥棱镜的组合作为敏感元件,利用二维角度激光测量及迈克尔逊干涉原理,可以在较高精度下同时提取并实时测量三维加速度信号.对该传感器进行了系统的理论研究,给出了该三维加速度传感器的结构设计、测量原理以及其参数和性能指标.这种新结构的激光加速度传感器,可望在较恶劣工作环境下的发动机故障检测,运动制导等领域中发挥重要作用.     

分布参数系统传感器位置优化策略的小波算法

传感器位置配置是分布参数系统实现最优控制的关键问题之一，不仅和边界条件有关，还和输入信号、系统噪声、测量噪声、过程的动态特性等因素有关，各个因素对最佳测量位置的影响各不相同。分布参数系统状态在空间具有无穷维自由度，而测量通常只是在空间离散的有限个点上进行，并且受到噪声的污染，因此，选择分布参数系统测量位置具有重要的意义。本文基于正交函数逼近理论，用小波作为分析工具对分布参数系统的传感器测量点的位置优化问题进行研究。仿真结果表明：该方法对于分布参数系统的传感器位置的优化选择具有重要意义。     

寄生式时栅角位移传感器误差源分析与验证

为了提高寄生式时栅角位移传感器的精度,深入分析误差源产生机理和变化规律,确定其主次影响因素,通过对传感器结构分析和行波公式推导分析,得到寄生式时栅角位移传感器的主要误差来源,包括两相激励信号时间、空间正交性误差以及驻波信号幅值误差、线圈零点残余电压引起的误差等.对各误差分量的具体谐波频率次数进行理论推导,确定了产生不同谐波误差分量的具体原因,并通过实验进行验证.验证结果表明:导致传感器产生零点残余电压的误差影响因素对传感器测量精度的影响最为显著,为寄生式时栅传感器的主要误差来源;激励信号的时间、空间正交误差及两列驻波信号的幅值不等为次要来源.     

一种双轴差动自感式传感器

主要介绍一种双轴差动自感式传感器的结构原理及测量线路,分析计算了双轴差动自感式传感器的标度因数和相位差;分析了在工程实践中测量电路、气隙长度与铁芯截面面积,以及铁芯短路,线圈匝间短路和分布参数对测量精度的影响。同时,针对电磁反作用力矩对测量精度的影响,通过计算分析,利用提高激磁电源频率、降低激磁电压方案,能够有利于双轴差动自感式传感器零位的调节,减小了电磁反作用力矩带来的测量误差。     

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