巧用比较指令实现抢答器的PLC控制

介绍了一种利用S7-200 PLC实现数码管显示并且设计简单的4人抢答器,它以比较指令、译码指令实现其功能.与一般的利用互锁指令相比,此设计更加简单,适于多人抢答.     

运算器中全加器标志位的逻辑设计与应用

介绍全加器实现逻辑基础,给出4个常用标志位的生成逻辑,重点分析借位标志和溢出标志的生成逻辑,并给出标志位在MACH芯片中的实现过程。最后给出标志位在比较转移等指令中的应用方法。     

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。     

多种单按钮启停控制的PLC程序设计方法

运用S7-200中的计数器指令、移位寄存器指令、SR触发器指令、置位和复位指令、基本逻辑指令均可实现单按钮电动机的启停控制.采用PLC控制时,要考虑PLC的输入、输出点数,点数使用越少,越能节约资源、降低成本.     

利用可编逻辑阵列设计七段译码器

应用可编逻辑阵列的思想扣方法来设计七段译码显示器，通过严密的逻辑推导扣计算，得出组合逻辑表达式，深化了对可编逻辑的认识，并总结了PLA结构的一般化简原则．     

基于MIPS指令集的流水线CPU设计与实现

提出了一种CPU设计方案,实现指令集为MIPS指令集中选取15条指令作为本CPU的基本指令,采用基本5步流水线CPU设计。分析了流水线CPU的逻辑结构与指令的处理过程,给出了取指阶段IF、译码阶段ID、执行阶段EX、内存访问阶段MEM、寄存器写回阶段WB阶段的设计与实现。对流水线产生的相关性问题,采用Bubble法和Forwarding法相结合的方法来消除相关性,在FPGA平台上进行了测试,测试结果表明,该方案符合设计要求。     

数字电路仿真实验及其设计示例

利用电子线路仿真分析平台Electronics Workbench(简称EWB)在组合逻辑电路及时序逻辑电路实验课的仿真分析中需要进行验证性实验的设计。组合逻辑电路:七段译码显示电路,8线-3线优先编码器功能测试;利用EWB所提供的字发生器(Word generator)及显示仪器中的发光元件测试RS、JK、D触发器的功能,仿真分析数据的串行—并行转换,二分频的验证;利用74160采用复位法及置位法接成七进制计数器与采用74190置位法接成七进制计数器进行比较分析,明确复位法与置位法的区别,搞清置位法中预置数操作与时钟脉冲有关与无关设计设计方法的不同。     

逻辑标志值程序设计法在PLC编程中的应用

传统的PLC对继电控制和逻辑控制的编程方法上都采用传统的设计方法,如启保停电路设计法,置位复位指令法以及顺序控制指令法等,这些方法对简单的顺序控制非常实用,但是在实现复杂的逻辑控制时显得非常困难,我们发现采用逻辑标志位来解决复杂逻辑控制效果非常好,程序简洁,可靠,编程方便.     

PLC实现顺序控制的编程方法

顺序控制在工业控制中是一种常见的控制，PLC实现顺序控制的主要任务就是用户程序的设计，本以日本三菱F1系列小型可编程序控制器为例，讲述了用基本逻辑指令，移位寄存器，步进梯形指令三种编程方法，由于各厂家生产的PLC都有基本逻辑指令，因而用基本逻辑指令编辑较为广泛，但一般程序较为烦琐，不易检查，本的方法较为清晰，易于掌握，用移位寄存器对单一序列易于控制，对其它的控制较为困难，用步进梯形指令编程最为简单直观，但一些型号的PLC没有该指令，受到一定的限制，因此三种编程方法各有其特点，可根据控制对象具体情况来选择控制方法。     

用数据选择器实现组合函数的方法

介绍了用中规模集成电路数据选择器实现组合逻辑函数的三种方法:常用方法、扩展法、降维法。阐述了如何实现组合逻辑函数,并对实现方法进行了分析与比较,指出了一种行之有效的方法。     

七段显示译码器的研究

随着电子技术的快速发展,人们对产品操作使用的快捷性、方便性及直观性提出了更高的要求。而七段显示译码器常常配套使用在各种电子设备中,极大地方便了这些设备的操作过程。文章详细介绍了它的理论设计过程和电路板的制作,使读者能从专业的角度对其有系统化的认识。     

基于Nios Ⅱ的JPEG图像显示系统研究

随着多媒体通信技术的发展，人们不再满足单一 文字或声音的传递，从普通电话到视频电话，从SMS (short mess呼ng serviee)到EMS(enhaneed message serviee)再到MMS(multimedia mess铭ing serviee)，多 媒体技术逐渐进人千家万户。因此，研究如何高效地 处理多媒体信源，让其更     

Toward a set of design principles for decoding training: A systematic review of studies of English as a foreign/second language listening education

Listening is a major challenge for many English as a foreign language (EFL)/English as a second language (ESL) learners. Many learners find it difficult to immediately process and segment an ongoing stream of sounds. Decoding training is one of interventions that have been used to assist EFL/ESL learners. This paper reviewed empirical studies of the effectiveness of decoding training in developing EFL/ESL learners' listening. We examined the following four major factors: (a) the types of instructional activities used; (b) the effects of decoding training on student listening outcomes; (c) the main instructional enablers of decoding training; and (d) the main instructional barriers to decoding training. The two activities most frequently used for decoding training were dictation and pronunciation instruction. A meta-analysis of 13 intervention studies showed an overall significant effect in favor of decoding training over non-decoding instruction for listening education (Hedges's g = 0.553, CI = 0.348–0.759, 95% confidence interval, p = 0.000), with no evidence of publication bias. Two theoretical frameworks, cognitive learning theory and the attention, relevance, confidence, and satisfaction model, were used to synthesize 33 studies to analyze the common elements that promote and hinder the development of learners' decoding skills. We proposed a set of design principles for decoding training that are expected to enhance the effectiveness and efficiency of decoding training in EFL/ESL listening education.     

Critical Elements of Classroom and Small-Group Instruction Promote Reading Success in All Children

The components of effective reading instruction are the same whether the focus is prevention or intervention: phonemic awareness and phonemic decoding skills, fluency in word recognition and text processing, construction of meaning, vocabulary, spelling, and writing. Findings from evidence-based research show dramatic reductions in the incidence of reading failure when explicit instruction in these components is provided by the classroom teacher. To address the needs of children most at risk of reading failure, the same instructional components are relevant but they need to be made more explicit and comprehensive, more intensive, and more supportive in small-group or one-on-one formats. The argument is made that by coordinating research evidence from effective classroom reading instruction with effective small-group and one-on-one reading instruction we can meet the literacy needs of all children.     

硬盘录像机编解码的实现研究

简述MPEG-2编码标准的特点及其核心技术,根据MPEG-2编码标准以及DVR系统的特点,应用单片机和可编程逻辑器件等控制芯片,设计了一个DVR编解码系统,并介绍了编解码过程。     

Reorganizing the instructional reading components: could there be a better way to design remedial reading programs to maximize middle school students with reading disabilities’ response to treatment?

The primary purpose of this study was to explore if there could be a more beneficial method in organizing the individual instructional reading components (phonological decoding, spelling, fluency, and reading comprehension) within a remedial reading program to increase sensitivity to instruction for middle school students with reading disabilities (RD). Three different modules (Alternating, Integrated, and Additive) of the Reading Achievement Multi-Modular Program were implemented with 90 middle school (sixth to eighth grades) students with reading disabilities. Instruction occurred 45 min a day, 5 days a week, for 26 weeks, for approximately 97 h of remedial reading instruction. To assess gains, reading subtests of the Woodcock Johnson-III, the Gray Silent Reading Test, and Oral Reading Fluency passages were administered. Results showed that students in the Additive module outperformed students in the Alternating and Integrated modules on phonological decoding and spelling and students in the Integrated module on comprehension skills. Findings for the two oral reading fluency measures demonstrated a differential pattern of results across modules. Results are discussed in regards to the effect of the organization of each module on the responsiveness of middle school students with RD to instruction.     

Putting struggling readers on the PHAST track: a program to integrate phonological and strategy-based remedial reading instruction and maximize outcomes

PHAST (for Phonological and Strategy Training) is a research-based remedial reading program that attempts to capitalize upon current research on reading disabilities and their remediation. The focus of the program is on the primary obstacles to word identification learning and independent decoding that most disabled readers face and the steps necessary to help these children achieve independent reading skills. A framework of phonologically based remediation was used as a foundation upon which a set of flexible and effective word identification strategies were scaffolded in an integrated developmental sequence. The program uses a combination of direct instruction and dialogue-based metacognitive training, with the pedagogical emphasis shifting from an initial direct instruction, remedial focus to increasingly metacognitive-strategy-based methods. A continuum of intervention over 70 hours provides both (a) remediation of the basic phonological awareness and letter-sound-learning deficits of disabled readers and (b) specific training of five word identification strategies that offer different approaches to the decoding of unfamiliar words and exposure to different levels of subsyllabic segmentation. Explicit instruction in the application and monitoring of multiple word identification strategies and their application to text-reading activities continues throughout the PHAST Program. PHAST training provides the disabled reader with the opportunity to become a flexible reader who approaches new words in or out of context with multiple strategies and has the ability to evaluate the success of their application. The PHAST Program was developed following the controlled evaluation of its components in laboratory classroom settings and recent positive results from their sequential combination. PHAST represents a new integrated approach to programming in this area using instructional components that have already demonstrated their efficacy with children with severe reading disabilities.     

基于单片机的球赛计时计分器设计

由单片机AT89C51编程控制、LED七段数码管作显示的球赛计时计分系统具有赛程定时设置、成绩即时刷新及成绩暂存等功能;具有价格低廉、性能稳定、操作方便且易携带等优点;可广泛应用于各类学校和小团体的球赛中。     

Teacher-Directed Decoding Practice with Manipulative Letters and Word Reading Skill Development of Struggling First Grade Students

We compared the effects of two approaches to decoding on the word reading skills of struggling first-grade students: decontextualized, teacher directed decoding practice with manipulative letters and embedded, incidental decoding practice. Participants were 98 students at risk for reading disability. We randomly assigned participants to three groups: (1) treatment, (2) comparison, and (3) control. The treatment group received 30 sessions of small-group instruction using manipulative letters to practice decoding skills. The comparison group received the same small-group reading instruction without the additional decoding practice. The control group did not receive supplemental small-group instruction. Analyses indicated that students who received the additional decoding practice with manipulative letters scored significantly better on phonological awareness, decoding, and word recognition skills than students who received incidental decoding practice.     

Explicit Instruction in Decoding Benefits Children High in Phonemic Awareness and Alphabet Knowledge

This article reports a study of 32 children who had been trained to a high level in phonemic awareness and alphabet knowledge over a 12-week period at preschool. During their first 6 weeks in kindergarten, these phonemically aware children were taught to read 10 real words, using either decoding and encoding techniques or a whole word method. At posttesting the children taught by the decoding and encoding method were superior in reading and writing both novel real words and pseudowords, compared to the whole word group. The results support the contention that explicit instruction in decoding is helpful even when children have high levels of phonemic awareness.