基于Petri网的PLC程序设计

随着生产过程复杂性的增加,对系统的控制也更加复杂.传统的PLC程序设计方法,已不适用于诸如协调、竞争等控制的设计.需要寻求新的程序设计方法来满足复杂的控制要求.本文介绍了基于Petri网的PLC程序设计.     

AS/RS中输送系统的PLC程序设计

自动化立体仓库(AutomatedStorageandRetrievalSystem,AS/RS)是现代物流系统的一个重要组成部分,广泛地运用于各行各业中。目前,它已成为企业生产自动化和管理信息化的标志之一。随着生产过程复杂性的增加,对系统的控制也更加复杂,传统的PLC程序设计方法,已不适应于诸如协调、竞争等控制的设计,需要寻求新的程序设计方法来满足复杂控制的要求。本文根据Petri网的设计思想,采用功能表图构造数学模型,在模型的基础上进行自动化立体库中输送控制系统的PLC编程设计。     

PLC控制系统编程技巧及其应用

程序设计是PLC应用系统设计的工作重点,往往也是难点。文章结合三菱PLC的控制实例,介绍了化整为零、层次递进 集零为整、衔接优化的编程技巧及其应用方法。掌握了这种编程技巧,则无论遇到一个多么复杂的控制系统设计难题,都会迎刃而解。     

过程控制编程方法在冷轧清洗线中的应用

针对复杂的过程控制系统,采用可编程控制器(programmable logic controller,PLC)线性化编程方法,软件的开发和维护都很困难,甚至出现所开发的软件不可用的严重问题,往往不能满足客户需求。该文采用面向对象的方法对PLC过程控制系统进行程序设计,使得程序设计更加简单,设计的系统更加可靠,后续开发更加方便,并且利于代码复用。将此方法应用于鞍钢冷轧清洗线PLC过程控制中,使得大型PLC程序在集体合作设计时分工更加明确,现已投入实际运行,实践证明控制性能更加可靠,提高了带钢的质量,取得了一定的实用价值和经济价值。     

基于PLC的PID控制器设计与实现

为了方便构建PID控制器,降低PID控制器难度,减少投资,通过对PID控制算法和PLC性能分析,提出了基于PLC的PID控制器的3种实现方法,并以借助PLC内置PID指令为例,介绍了基于三菱可编程序控制器FX2N-16M在温度控制中的PID控制程序设计,给出了完整的温度PID控制梯形图.通过实验,证明该方案可行,控制效果良好.     

应用结构化编程实现交通信号灯的控制

基于西门子S7—300程序结构,针对PLC常用编程,提出了在程序设计中使用功能块,采用结构化程序设计实现控制要求的方法。结合交通信号灯控制的程序实例,阐述了此方法在PLC编程中的应用。     

PLC程序设计工程化教学方法探讨

针对PLC程序设计教学过程中存在的问题,以实际工程项目中经常出现的设备启停的控制为例,提出了PLC程序设计工程化的教学方法:首先对程序设计工程化的教学背景与必要性作了分析,接着对工程化教学的内容与方法作了探讨,最后对工程化教学的效果进行了总结。实践结果表明:程序设计工程化的教学方法是可行的,这种教学方法激发了学生的学习兴趣,使学生建立了良好的工程化程序设计思路,掌握了规范化的工程化程序设计方法,提高了实际工程编程能力。     

十字路口交通信号灯系统设计

本文介绍了一种用PLC控制的城市十字路口交通信号灯控制系统的控制程序设计,文中根据交通灯控制系统的控制要求,详细的阐述了设计方案的选择以及整个程序设计的过程。     

三菱PLC技术在多灯循环闪烁控制电路中的应用

针对多灯（如3灯、8灯和16灯）循环闪烁实际控制要求的不同,灵活运用三菱PLC功能指令编程方法,进行了PLC梯形图程序设计,并对程序运行功能予以了简单分析和说明。     

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.     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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     

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