一种新型电涡流传感器的理论分析

为提高普通电涡流传感器的灵敏度和增大检测距离,对一种新型电涡流传感器从理论上进行了分析.文中列出了重叠双线圈和同轴三线圈两种电涡流传感器的结构,并利用电磁场相关理论对同轴三线圈电涡流传感器及其设计进行了较详细地分析,并给出了测量电路单元.通过与普通电涡流传感器线圈进行仿真比较,得出了该结构电涡流传感器在长距离测量时的优缺点.     

电涡流传感器在位移测量上的应用

电涡流检测技术是一种无损、无接触测量的检测技术。由于电涡流检测采用了具有结构简单、灵敏度高、测量线性范围大、抗干扰能力强、不受油污介质影响的电涡流传感器,因此在位移、厚度等方面的测量获得广泛的应用。作者在应用电涡流传感器测量位移时,为了正确可靠地测量位移量的大小,对电涡流位移传感器作了静态特性的测试分析。     

电涡流传感器的有限元仿真研究与分析

电磁场的分布情况是影响电涡流传感器灵敏度和线性度的主要原因。从电涡流传感器的基本原理出发,采用有限元方法,利用ANSYS语言,通过建模、定义材料特性、划分网格、设置边界条件、加载及求解等,对电涡流传感器的电磁场进行仿真研究,并由理论公式验证模型的正确性。通过计算3种尺寸参数不同的线圈,研究分析了线圈的形状结构对传感器灵敏度和线性度的影响,对于电涡流传感器线圈的设计具有指导意义。     

双线圈结构电涡流位移传感器的设计

根据电涡流检测原理,采用双线圈结构设计电涡流位移传感器探头,并结合由信号源、直流电源、信号处理和显示等模块构成的测量电路进行实验.实验结果表明,双线圈电涡流位移传感器具有输出信号稳定、抗干扰能力强、测量精度较高、电路简单、成本低等特点.     

影响电涡流传感器特性的因素分析

本文结合电涡流传感器的特点,阐述了不同材料的被测体和不同参数的探头对传感器特性的影响,讨论了借助微型机分析传感器特性的方法,其结果对电涡流传感器系列化生产和设计及传感器的标定具有实际意义。     

电涡流传感器温度稳定性研究

为了提高磁悬浮轴承高频电主轴控制系统中电涡流传感器的温度稳定性,针对恒频调幅式电涡流位移振动传感器,分析了电涡流传感器的基本结构和工作原理,建立了检测电路数学模型,找出了影响其温度稳定性的主要原因,并提出了对激励信号进行稳频、稳幅,尽量减小检测线圈等效损耗电阻以及差动补偿等提高温度稳定性的措施。作者在此基础上研制出的精密差动式电涡流位移振动传感器,在实际运行中温度系数达到２×１０－ ４℃－ １ 以上,长期稳定性优于０．５％ 。     

平面电涡流线圈的结构参数设计

为提高平面电涡流传感器的灵敏度,以Biot-Savart-Laplace定理为基础,研究了传感器线圈结构参数对其灵敏度的影响。推导了平面电涡流线圈的磁场分布梯度公式,仿真计算、分析了不同结构参数条件下线圈的磁感应强度-距离曲线,并进行了实验验证。结果表明:增加外径和圈数,减小内径,可以有效地提高平面电涡流线圈的灵敏度。     

基于FPGA的数字化电涡流位移传感器设计

电涡流位移传感器的载波信号和解调信号均为模拟处理信号,其测量和解调电路均会提高硬件电路复杂性和信号的不稳定性,并增大磁轴承系统的总体设计体积和功耗等。针对这一问题,该文设计了以调幅式电涡流位移传感器为基础的数字化电涡流位移传感器。利用现场可编程门阵列(FPGA)的数字输出信号设计传感器的载波信号,通过FPGA的软件设计对测量电路的输出信号进行数字化处理。该设计在有效降低电路设计复杂性和功耗的同时,提高了传感器测量的可靠性和精确性。     

多层金属膜厚度的无损测量研究

提出一种用电涡流传感器实现无损在线测量工件金属膜厚度的方法。给电涡流传感器同时施加3种不同频率的激励信号,通过传感器与各层金属膜所感应的电涡密度,可以间接获得2层不同材料的金属膜厚度,同时还可获得传感器与表层被测工件表面的距离。理论分析和实验结果表明了这种方法的可行性。     

利用电涡流位移传感器寻迹设计

该文谈论为了实现对强磁、强光环境中智能车的寻迹方法,展开对涡流式传感器的研究。利用电涡流位移传感器的基本原理,检测参考物铝箔位置的变化对传感器阻抗的影响,判断阻抗的变化做出位置的判断。     

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     

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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