智能通道计数器的设计与研究

本文研究的是一种智能通道计数器,它不但可以计数,还可以识别通道物体的通过方向。主要用来保证危险场所人员安全,具有重要的实际意义。它是通过光电传感器来采集信息再由PLC控制系统来实现控制的。其工作可靠,结构简单、造价低,有很好的开发前景和运用价值。是PLC在控制方面,软件编程的又一次灵活的实际应用,具有突破性、开发性和实用性。     

计算机仿真在PLC教学中的应用

电梯的PLC控制是PLC教学中的重要应用,为了让学生了解电梯PLC控制的控制流程,验证学生所编制的PLC程序的正确性,需要通过实验进行教学,但考虑到实验条件、经费和安全性的问题,因此利用计算机仿真软件来完成电梯的PLC控制实验。用Visual Basic 6.0设计PLC实验虚拟对象,通过PLC与计算机的通信就可以实现PLC一动作,实验虚拟对象就发生相应动作的效果。     

煤矿工业控制综合自动化及千兆环网

1.PLC控制系统的工作原理 PLC是一种工业控制计算机,因此它的工作原理是建立在计算机工作原理的基础上,通过执行反映控制要求的用户程序来实现的。但是其程序执行时按照程序的顺序依次完成相应各电器的动作是一种串行工作方式。PLC是按照集中输入、集中输出、周期性循环扫描的方式进行工作的。     

浅谈电气设备自动控制系统中PLC的设计与运用

随着PLC功能的不断提高和完善,PLC几乎能完成电气设备控制领域的所有任务.在很多情况下,PLC可以取代工业控制计算机作为主控器来完成复杂的电气设备自动控制任务.本文主要研究PLC控制系统的设计方法和其在电气设备上的运用,提供了一条清晰的PLC控制系统设计思路,供大家参考.     

PLC控制的光电导引式AGV的设计与实现

利用西门子S7-200CPU226PLC作为控制核心设计了一种AGV。采用光电传感器作为导航传感器进行路径识别,通过PLC控制使其按照预定的路线行驶,并能自主判断货物方位和将货物运送到指定位置。实验测试表明,该AGV能够自动搬运货物,对提高劳动生产效率具有较高的实用价值。     

PLC控制技术一体化教学方法研究

PLC采用可以编制程序的存储器,与传统的工业控制装置相此具有结构简单、编程方便、性能优越等特点,满足了现代工业发展的要求.可编程控制器PLC是一门实践性很强的课程.该文以PLC控制技术为切入点,在概述PLC控制技术的应用现状的基础上,重点探讨了PLC控制技术一体化教学方法,旨在说明PLC控制技术教学中,PLC控制技术一体化教学方法的重要性,以期为PLC控制技术教学提供参考.     

PLC的SFC图在编写顺序控制梯形图中的应用

为了解决应用可编程控制器(PLC)的基本逻辑指令编写顺序控制梯形图时所存在的编程复杂、不易理解等问题,采用PLC的顺序功能图来编写顺序控制梯形图是一种非常有效的方法,该方法具有编程简单而且直观等特点.以送料小车的控制为例,采用顺序功能图的方法编写其控制梯形图,从编程结果可以看出,与应用PLC的基本逻辑指令方法相比具有简单、直观、逻辑性强等特点,提高编程的效率.     

微粉超微粉生产线控制技术研究

提出一种基于工控机与可编程控制器(PLC)的微粉超微粉生产线自动控制系统.根据微粉超微粉生产的工艺和特点,分别建立了微粉超微粉生产线的生产流程、控制方案,设计了控制系统的总体结构与配置、PLC的输入输出通道,完成系统通信设计以及控制软件开发.控制系统采用工控机作为上位机,用于监控和设定系统参数,PLC作为下位机实施数据采集和输出控制,采用上位链接模式实现二者的通信.系统具有手动/自动切换、生产线自动延时顺序启动和停机、状态监测和故障报警等功能.     

参数表以及模块化编程在中药发药机PLC控制程序中的应用

在介绍基于S7-200 PLC编程控制中药配方颗粒自动发药机工作的基础上,分析了参数表以及模块化编程在中药发药机PLC控制程序中的应用.参数表是指将大量参数以表的方式存储到PLC的变量存储器中,在PLC功能模块中通过指针引用来实现对参数表的访问.只读参数表也称为静态参数表,可以通过程序修改参数值的称为动态参数表.经实验证明,参数表以及模块化编程的应用大大简化了参数初始化过程,并使得PLC控制程序逻辑结构清晰,提高了程序的可读性与可维护性.     

PLC外接模拟量模块的1种新方法

通过PLC通信端口外接模拟量模块的方法,可以充分利用PLC灵活多样的控制功能,并针对控制对象的特点采取特殊处理,此方法具有一定的通用性.     

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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