微机导频调节器

微机导频控制器是一种利用微机作为控制部件实现自动电平调节的设备。试验系统以ZL-3型60路载波正、倒频谱6个导频为设计对象进行扫描控制。控制器周期性地采集各个导频电平,并进行相应的控制处理。通过导频控制器的输出电压控制热敏电阻,从而改变调节网络的增益,达到稳定传输电平的目的。     

明线十二路载波电话系统设计

鉴于祖国进行大规模地建设并开始自己制造多路载波电话通讯设备,这篇报告及时地提出架空明线十二路载波电话系统的新型设计方法.报告内容包含频率分配和变换程序,传输质量和电平选择,频率交叉法使用问题,压缩扩展器使用问题,以及自动调节电平设备,振铃讯号设备,终端机和增音机设备,线路进站和远距供电设备等各种制度的选择和比较,都提出初步意见,以供讨论.一、应用目的和经济意义二、频率分配和变换程序的讨论三、传输质量和电平选择的讨论四、频率交叉法使用的讨论五、压缩扩展器使用的讨论六、调节电平设备的讨论七、振铃讯号方法的讨论八、终端机和增音机设备的讨论九、线路进站设备的讨论十、远距供电设备的讨论参考交资料     

基于FPGA的超声波碎石系统控制器研究与实现

设计一种基于FPGA的超声波碎石系统信号发生与自动调节输出控制器。采用FPGA实现直接频率合成技术,采用FPGA监控换能器两端输出电压与电流的TTL电平信号,根据电流、电压相位差来控制输入正弦波信号的频率,最终实现控制器的设计。实验结果表明,该控制器输出信号稳定,系统反馈调节精度高。     

电话语音信箱

本文主要介绍电话语音信箱的系统硬件设计，系统软件编制。着重介绍电话的无人值守、电话留言、留言查询、自动拨号的功能，以及ＤＴＭＦ信号的软件解码、发送电平的软件调节、中断向量的修改等问题。     

基于MMC的永磁同步电机驱动系统新型电容电压控制策略

为改善模块化多电平永磁同步电机驱动系统的控制性能,对变换器的双星半桥型拓扑结构进行改进,并建立上桥臂和下桥臂中子模块电容电压可变控制的原理分析模型,提出一种根据电机运行速度灵活调节变换器电容电压的新型控制策略,与传统控制方法下变换器的电容电压恒定相比,此新型策略为驱动系统多增加了一维控制量,使系统在灵活性和准确性控制方面得到了明显改善.在实验室中搭建了模块化五电平永磁同步电机驱动系统测试平台,实验结果表明,该新型电容电压控制策略能够有效地控制和调节变换器各个子模块的电容电压,有利于降低系统损耗和改善电机控制性能.      

固态数字语音记录中的ALC

用固态存储技术进行语音记录时 ,需解决自动电平控制问题。探讨了固态语音记录中进行自动电平控制的几种方法 ,介绍了其工作原理和电路结构 ,并就语音时间记录仪中实际采用的分离元件 ALC电路的工作原理进行了讨论 .     

基于三电平逆变器的DSTATCOM装置设计

提出了一种基于三电平逆变器的DSTATCOM无功补偿装置及其保护系统的设计方案.介绍了装置主电路结构和参数选择的规则,采用数字信号处理器TMS320LF2407A为控制芯片并利用文献提出的一种三电平SVPWM简化算法来实现装置对配电网负荷的无功补偿.实验结果表明,该装置具有快速调节无功的能力和输出电流谐波小等优越性能.     

带式输送机液压自动拉紧控制系统

介绍了大型带式输送机张力自动调节的必要性,阐述了带式输送机张力液压自动调节装置的调节原理,设计了一种新型的带式输送机张力的液压自动拉紧系统,分析了拉紧装置的特性并构造了拉紧系统的传递函数,在此基础上构建了使用这种控制系统的带式输送机的动力学模型和数学模型.并利用该模型分析了输送带张力自动控制过程,用实例分析了张力自动控制系统的性能,应用simlingk软件进行了系统仿真,结果证明这种液压自动拉紧系统具有较好的适应性和稳定性.     

基于单片机的简易波形发生器电路的设计

本系统采用89C51单片机作为波形发生电路的核心控制器件,通过输出相应的高低电平输出方波波形,通过正比例函数关系拟合三角波形输出,通过编制正弦表实现正弦波形的输出,分别从相应端口实现数字量赋值,采用数模转换芯片DAC0832实现数字量向模拟量的转换,得到相应的模拟输出波形;利用按键调用不同的数字编码表控制不同波形的输出;通过调用不同的延时函数实现频率的调节;通过运放的调理实现幅度的调节;通过电平转换器实现从方波向TTL电平输出的转换.     

绳索牵引自动水平调节机器人的设计

为解决装卸过程中贵重载荷的水平调节问题,在分析了现有调节技术和装置优缺点的基础上,设计了绳索牵引自动水平调节机器人完成倾角调节.介绍了绳索牵引自动水平调节机器人的总体结构设计,根据力平衡、力矩平衡以及几何约束条件推导了系统的二维模型,用相似的方法从2种不同思路分别建立了系统的三维模型,讨论了2模型各自的优缺点.简要说明了控制系统的相关问题(结构设计、原理)和系统基本工作流程,总结了机器人系统的主要特点.     

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