编码器换向误码输出原因探讨及鉴相电路改进

从编码器的结构特点出发,探讨了编码器频繁换向时输出信号中存在误码脉冲的原因。根据编码器输出信号不能同时跳变的特点,设计了一种更简单有效的双向触发鉴相电路。该电路通过标记两相输出信号跳变时刻的状态,经过一定的逻辑与运算,有效地滤除了输出信号中存在的误码脉冲。经实验室应用证明,该电路具有较好的误码滤除效果,为编码器内部电路的改进及其输出信号的数字处理提供了一种新思路。     

用于交直流伺服系统的编码器信号频/压变换电路

介绍一种具有极性判别功能的频率电压转换电路的原理．它可以根据正交输出型编码器信号的相位关系，输出具有正负极性的模拟电压信号．针对交直流速度伺服系统的光电编码器信号电压变换问题，给出了基于LM2907的F／V转换器的双极型频压转换电路．     

故障-安全型输出电路的研制

一个电路输出直流信号时，往往需要快速地、准确无误地控制其输出信号的通断。文章介绍一种必须由一定频率的脉冲信号控制，才有直流信号输出的电路，且当电路中任一元件损坏时，输出均为低电平。整体电路符合故障－安全特性的要求。     

角位移传感器信号处理电路设计

利用增量式光电编码器进行角位移检测的原理及硬件电路的实现方法．通过对编码器输出信号的处理,形成正、反向判别信号和４倍频计数脉冲,实现角位移的精确检测．     

高精度增量式光电编码器信号处理系统

为提高增量式光电编码器的输出精度,减小信号处理电路复杂度,提高伺服控制系统的稳定性,研制了一种单圈输出32 400 周期方波信号的高精度增量式光电编码器。该编码器外径为90 mm,码盘一周刻划3 240 线,数据处理系统可完成对莫尔条纹信号的40 倍准确细分。实验结果表明,此编码器输出信号精度正交性偏差小于15%,均匀性偏差小于20%,大幅减小了应用增量式编码器时伺服系统的抖动。     

旋转编码器抗抖动信号处理电路及其角度测量应用

采用旋转编码器作为帆板控制系统的角度传感器件,帆板转动时,编码器产生两路正交信号,经过辨向处理后,送单片机进行计数处理,其正向脉冲和反向脉冲之差乘以角度当量即为实际角位移。在实际进行动态测量时,帆板达到动态平衡位置时往往会产生高频尖脉冲,而此时实际帆板并未发生角度的改变,该读数被单片机误计后,会造成实际的计数紊乱,对角度无法进行精确控制。针对该情况,开发了抗抖动信号辨向倍频处理电路,提高了系统的抗干扰能力和分辨率。该处理电路适用于其他输出信号为两路正交方波或者正弦波的位置检测传感器。     

计数器实验中出现的问题及处理

在脉冲发生器输出端后加一级驱动电路,再接入计数器的时钟脉冲源输入端,可有效地避免通常发生在实验过程中计数器不规则的跳变。同时用双踪示波器观察计数器输出波形时,采用周期长的信号作为示波器内触发源信号可观察到多路准确的波形。     

零脉冲高分辨率磁编码器的研制

编码器在许多应用场合要求敏旋转１个周期给出１个零脉冲信号，要满足这一使用要求，在前期增量型高分辨率磁编码器的研究基础上，对具有零脉冲信号输出的磁编码器的结构设计、信号触发磁鼓的试制、磁敏电阻敏感元件制备、电子信号处理的研制过程进行讨论。     

超低频移相信号发生器的研究

针对模拟电路信号发生器电路存在的输出信号的频率和波形的精确度难于保证等缺点，采用直接数字波形合成技术，设计了一种晶体稳频超低频移相信号发生器，该信号发生器不仅可对输出信号实现数控调频，调相和波形选择，而且具有稳定性好和调节精度高等特点。     

彩电副载波恢复电路的研究与调试

副载波恢复电路的测试与调整是金星Ｃ４７１７型彩电基板测试系统的一部分，该电路由晶体振荡器与移相电路组成，本文对该电路作了较详细的分析，从而导出了调整该电路的方法，当信号存在误差时，应该调整哪些元件，或当存在信号偏差时，哪些元件值有偏差，这也是该系统的一个特点，由于该系统用于整机调试，所以要在最后的输出中发现该部分的问题，这也有一定难度，这一方面也作了一定说明。     

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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