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61.
利用嵌入式技术,使用FPGA实现了多路全双工串口.该系统在接收端和发送端前都加一个具有8个缓冲单元的FIFO,实现内部模块时钟与串口速率匹配,同时,发送波特率和接收波特率等参数能够根据需要来进行相应的配置,并在Altera公司的CycloneⅢ系列FPGA硬件平台进行验证实验结果,该设计完全符合串口通信标准.  相似文献   
62.
MSP430系列单片机是美国德州仪器公司生产的16位单片机,优点突出,它不仅低电压、超低功耗、而且有强大的处理能力、系统工作稳定、丰富的片内外设、有很高的性价比。文章介绍了以MSP430f149为处理器,采用双机异步通信的方式实现多路采集控制系统。结合外围传感器、无线模块电路,易于设计出低功耗、低成本的智能控制系统。  相似文献   
63.
如何使用AJAX技术,结合Web开发模式与研究领域的设计方法,研究AJAX客户端编程的理论,将AJAX与现有的软件开发模式相结合,具有很大的研究价值。分析总结了AJAX框架设计理论和方法,在此基础上开发了实际框架以支持Web应用,提出基于面向对象模式构建AJAX框架,该框架通过将应用模块化和编程对象化,可明显提高开发的效率和稳定性。作为一种B/S架构的开发框架,本框架为开发者屏蔽了多语言混合编程、网络传输、浏览器自适应等困难,提供了完全面向对象、跨平台、事件驱动等特性,有利于开发出功能强大的B/S应用程序,并使应用程序的维护和代码重用变得简单易行,提高开发效率。  相似文献   
64.
介绍了计算机异步通讯的原理、硬件连接、实验室中异步通讯的方法及部分软件接口。  相似文献   
65.
分析了同步电动机的功角特性,无功功率及功率因数调节,同步电动机的起动方法及起动时应注意的问题。  相似文献   
66.
在变频调速系统中,为实现变频器与上位机的远距离通信,通常采用串行通信方式。在详细分析了串行数据接口标准(RS-232、RS-485)的基础上,设计了上位机RS-232到RS-485的转换电路,并给出了基于TMS320LF2407A的变频器和上位机进行远距离串行通信的硬件接口电路、通信协议及软件设计方法,给出了上位机与下位机串行通信接口程序的初始化代码,同时阐述了如何通过VC 6.0中MSComm控件编写上位机串行通信程序。  相似文献   
67.
当今流行的IP和ATM技术各有所长,但由于它们在功能上的互补性,因此将两种技术结合应用到网络中才能得到比较完美的解决方案。本文介绍了这两种技术,并通过对比目前IP和ATM技术存在的异同点,阐述了将两种技术融合运用的几种方案。  相似文献   
68.
《图书馆管理杂志》2013,53(1-2):425-438
Abstract

Those called upon to instruct or moderate within the asynchronous environment must acquire the skills necessary to engage learners from across a distance. This paper will provide two case studies describing the experiences and practice of working in this environment. The first case study will describe the reference and instructional library support provided to the Master of Continuing Education program offered by the University of Calgary. The second case study will describe the services and resources offered by the Node Learning Technologies Network, particularly those aimed at librarians.  相似文献   
69.
Since a 1997 review by Karageorghis and Terry, which highlighted the state of knowledge and methodological weaknesses, the number of studies investigating musical reactivity in relation to exercise has swelled considerably. In this two-part review paper, the development of conceptual approaches and mechanisms underlying the effects of music are explicated (Part I), followed by a critical review and synthesis of empirical work (spread over Parts I and II). Pre-task music has been shown to optimise arousal, facilitate task-relevant imagery and improve performance in simple motoric tasks. During repetitive, endurance-type activities, self-selected, motivational and stimulative music has been shown to enhance affect, reduce ratings of perceived exertion, improve energy efficiency and lead to increased work output. There is evidence to suggest that carefully selected music can promote ergogenic and psychological benefits during high-intensity exercise, although it appears to be ineffective in reducing perceptions of exertion beyond the anaerobic threshold. The effects of music appear to be at their most potent when it is used to accompany self-paced exercise or in externally valid conditions. When selected according to its motivational qualities, the positive impact of music on both psychological state and performance is magnified. Guidelines are provided for future research and exercise practitioners.  相似文献   
70.
《学校用计算机》2013,30(3-4):67-80
Summary

This article reviews the development and delivery of a Higher Education course module as part of a large European University's Integrated Masters Program operating through a regional network of Rural Area Training and Information Opportunities (RATIO) telematic centres. The aim of the project was to provide remote learners living in the southwest of England with computer-supported solutions to access higher education as part of a technology-assisted distance education program. The module represented a shift from traditional educational delivery systems by using instructional courseware via an Internet Web site. Personal communications with module participants were conducted with the use of e-mail and videoconferencing information technology (IT) resources. Out of the original sixteen participants who enrolled in this Masters course module, four actually completed the learning sessions and two submitted final assignments. This article considers the key lessons learned from this attrition rate and shares the mainly positive experiences of the remote tutor and the students engaged in this initiative. The implications regarding the use of the Internet for delivering higher education course modules through online distance learning are discussed in the light of cautions learned from this research project and important practical recommendations for future practice are made.  相似文献   
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