一种PLC时序控制程序的编制方法

本文以三菱FX 2N系列PLC为例,介绍了一种PLC时序控制程序的编制方法,即应用触点比较指令将基准定时器的当前值分别与期望的若干个定时设定值相比较,用各触点比较指令的运行结果及其逻辑组合,来控制PLC的实际输出,实现PLC的时序控制功能。     

PLC中脉冲微分指令的巧用

本文主要阐述了如何将脉冲微分指令运用于程序设计中,实现检测外部常闭触点的断开信号、将外部常开触点持续闭合信号转化为脉冲信号,以完成控制要求;并且介绍了两种利用脉冲微分指令应用于程序中达到缩小机械控制的操作面板和节省PLC输入继电器的个数的方法。     

传送指令和移位指令在PLC编程中的应用

主要介绍S7-200型PLC传送指令和移位指令的特点和使用方法。以彩灯的流水控制为例,提出传送指令和移位指令的使用方法,并利用两种指令进行编程以及控制彩灯,可以方便快捷地完成控制任务。     

继电接触器控制系统与PLC的学习方法

要使初学者比较容易的接受并掌握 PLC工作原理和程序编制方法 ,关键是如何引导初学者从整体上把握 PLC与继电器控制系统的区别 ,并能够就常开、常闭触点与继电器组成的控制线路用 PLC中的梯形图和指令语句来描述 ,明确特殊性 ,把握本质之点。     

基于比较指令的交通灯PLC控制

采用比较指令和一个定时器实现交通灯控制,与采用顺序控制指令和多个定时器实现交通灯控制相比,设计程序简单且直观清晰．     

可编程控制器实用设计方法4种

介绍了可编程控制器实用设计方法四种即时序逻辑设计方法、状态转移图设计方法、经验设计方法、功能指令设计法,汇总了有触点继电器控制和无触点可编程控制通用的电路设计,为教学和工程实际实践提供了一种非常有用的方法,补充了许多教材中缺少设计原理的不足。     

基于PLC的四节传送带控制技术研究

教师采用三菱FX-1S系列的PLC实现四节传送带的模拟控制,在I/O分配的基础上,进行PLC梯形图程序设计和运行功能分析。在程序设计上采用基本指令和功能指令来实现对四节传送带的控制。     

“艺术彩灯造型”的PLC程序设计方法简介

文章介绍了“艺术彩灯造型”的PLC控制程序的设计方法.在编程中,运用定时器和区间比较指令为每一工步分配时间;运用交替输出指令产生“翻转”使程序变得简单;运用“逻辑设计法”编写译码输出程序.编程思路清晰,编程方法实用,能举一反三.     

PLC计数器的应用技巧

PLC是当今工业领域使用最广泛的一种新型自动控制装置,其功能指令和编程元件极为丰富。若功能指令和编程元件使用得当,运用灵活,将会得到较好的应用效果。掌握编程元件的应用技巧,对软件设计有很大的帮助。本文介绍三菱FX2N计数器一些应用技巧。1、计数器与定时器级联实现定时范围扩展图1为一个定时器与一个计数器级联的梯形图。图中,T2形成一个定时值为10s的自复位定时器。当X0接通,T2线圈得电10s后,其常开触点闭合,计数器输入一个计数脉冲,C0计数一次。下一个扫描周期则常闭触点断开,T2线圈失电自动复位。C0计数200次时,其常开触点闭…     

SIEMENS与FANUC数控系统复合循环指令在沟槽加工中的运用

复合循环指令通过指定切削参数、轮廓形状,由系统自动完成相关计算,控制刀具完成切削过程。而各系统厂家提供的复合循环指令各不相同,文章分别应用SIEMENS与FANUC的复合循环指令对沟槽进行加工,阐述了相关指令的应用技巧。     

大学英语听力策略培训实践研究

本章在听力策略培训相关研究的基础上,对听力策略培训的模式、教学方法、效果尤其是培训的内容等方面进行了探讨,并对融合式听力策略培训实验进行反思,得出关于听力策略培训、大学英语课程设置方面的启示.     

“零距离接触外来思想和文化”之修辞认同分析

《思想理论教育导刊》2013年第7期刊载黄科＂全国部分外语类高等院校思想政治理论课建设调研座谈会纪要＂。该文关注外语类专业思想政治理论课的教学效果,触及了思想政治理论课师资队伍的问题,并就改进思想政治理论课的有效性,加强教材建设、学科建设、教师队伍建设和创新教学方式方法等方面提出了建设性建议,但在＂现实困境＂归因方面,将＂外语类专业的特殊性＂等同于＂零距离接触外来思想和文化＂,于是必然带来＂对中国传统文化及道德理念的认同感产生不同程度的削减＂等提法有失偏颇。本文主要运用西方新修辞大师伯克的修辞认同说与该文作者展开学术对话,认为外语专业接触外来思想和文化与思政课程效果欠佳没有必然的联系;恰恰相反,这正是提高外语专业学生跨文化能力的必须途径。     

双语教学在医学教学中的应用

双语教学非常适合在医学教学中运用。它是通过英语教授医学专业知识,用英语进行课堂学习之间的交流和互动的一种教学模式。教学过程中,与单纯的英语教学相比,用汉语介绍一些相关的背景知识,可以帮助学生理解教学内容,以降低学生在英语理解上的难度。另一方面,在每节课结束时让学生用英语对所学的内容进行总结发言更能激发他们学习的主动性,进而提高他们用英语来表达和交流医学专业知识的兴趣和水平。     

C语言教学改革浅见

C语言程序设计教学需要改变传统的讲授加上机实验的模式,以适应现代教学的发展。从改变课堂教学方式培养学生学习兴趣切入,让学生了解C语言;通过艺术化的教学,使学生获得美的感受;设计问题引导学生将兴趣内化为学习需求。应用范例教学、支架式教学、任务驱动教学为学生创建学习的支持,并注意采用新评价方法促进学生学习,从而使学生的学习达到意义建构。     

Peer-Based Supplemental Instruction in STEM: Differences in Effectiveness Across Transfer and Nontransfer Undergraduates

Although there is a large body of research on the effectiveness of supplemental instruction for college undergraduates, very little of it has focused on transfer students, who often confront additional sources of stress and historically perform more poorly than their native student counterparts. In this study, we investigated the effectiveness of a peer-based supplemental instructional program in general and organic chemistry at a large state university over a six-year period, while considering differences across transfer and nontransfer students. The results suggest that the supplemental instruction improved outcomes overall but that nontransfer students benefit to a greater degree than transfer students, in the form of higher grades and pass rates, from attending supplemental instruction. The results suggest that peer-based supplemental instruction is a useful method to improve undergraduate student performance in chemistry, but more research is needed on ways to enhance the effectiveness of interventions in improving the performance of transfer undergraduate students in STEM fields.     

基于网络条件下英语写作课教学改革的尝试

基于网络条件下的英语写作课教学改革使传统课堂教学模式发生了根本的变化。通过实施课程形成性考核和终结性考试的整体设计,把考核与教学过程紧密结合起来,使学生的学习过程落到实处,从而实现科学地测评学生学习效果,促进学生自主学习,提高教学质量。本文就上述方面内容,介绍笔者作为课程辅导教师与评阅教师在教改实践中的几点尝试,希望为网络课程一体化考核改革的实验研究提供资料参考。     

Improving students’ proportional thinking using schema-based instruction

This study investigated the effectiveness of an instructional program (schema-based instruction, SBI) designed to teach 7th graders how to comprehend and solve proportion problems involving ratios/rates, scale drawings, and percents. The SBI program emphasized the underlying mathematical structure of problems via schematic diagrams, focused on a 4-step procedure to support and monitor problem solving, and addressed the flexible use of alternative solution strategies based on the problem situation. Blocking by teacher at three middle schools, the authors randomly assigned the 21 classrooms to one of two conditions: SBI and control. Classroom teachers provided the instruction. Results of multilevel modeling used to test for treatment effects after accounting for pretests and other characteristics (gender, ethnicity) revealed the direct effects of SBI on mathematical problem solving at posttest. However, the improved problem solving skills were not maintained a month later when SBI was no longer in effect nor did the skills transfer to solving problems in new domain-level content.     

Direct and Extended Vocabulary Instruction in Kindergarten: Investigating Transfer Effects

Abstract

The purpose of this study was to investigate the efficacy of an 18-week program of direct and extended vocabulary instruction with kindergarten students on both proximal measures of target word knowledge and transfer measures of generalized language and literacy. A second purpose was to examine whether treatment effects would be moderated by initial receptive vocabulary knowledge measured at pretest. In a quasi-experimental design, 80 kindergarten students from schools serving large at-risk populations were taught the meanings of 54 vocabulary words within interactive story read alouds over 36 half-hour instructional lessons (2 lessons per week over 18 weeks). An additional 44 students served as a no-treatment control. Findings indicated that students who received vocabulary instruction outperformed controls on a measure of target word knowledge as well as measures of generalized receptive vocabulary and listening comprehension. In addition, initial receptive vocabulary was strongly related to posttest performance on all measures. Implications are discussed in relation to supporting vocabulary development in the early grades within a multitier framework of instruction and intervention.     

在中职数学教学中实施问题教学法的探索

当前,问题教学法作为革除传统教学弊端的一种新兴的教学方法得到了广泛的关注和应用。笔者结合自身教学实践,从树立问题教学观念、培养学生问题意识和精心设置问题情境等三个方面对如何在中职数学教学中有效地实施问题情境教学法进行探讨。