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关键词： 公共节点   反馈  

摘要： 在放大电路中,采用不同的反馈电路可以改变电路的输入、输出电阻,影响电路的增益等。文章通过寻找形象直观的公共节点,阐述了用公共节点法来判断放大电路的反馈类型。

关键词： 交流接触器   印刷设备   工作原理  

摘要： 本文阐述了交流接触器的选用，介绍了交流接触器的工作原理和使用方法。印刷设备中常用交流接触器的选用主要通过交流接触器的结构与参数、交流接触器所带的负载和所处工作环境来综合考虑。

关键词： X射线机   继电器   医疗设备维修   交流接触器  

摘要： 介绍了在维修万东F108-V遥控透视X射线机的过程中遇到的一些典型故障及分析与维修过程。

关键词： 电缆分接箱   熔断器   环氧树脂绝缘筒   发热   烧毁   瓷体爆裂  

摘要： 介绍了几起10kV户外高压负荷开关电缆分接箱馈线熔断器及绝缘筒烧毁的现象;从连接器构造、材料及熔断器运行中发热两个方面探讨了能引起烧毁的原因;提出了整改及防范措施。

关键词： 实验室   功率放大电路   300B胆机   甲类放大器   直热式三极管   偶次谐波  

摘要： 四、晶体管串接单端直耦甲类功率放大电路 经典的胆机是在音响界被津津乐道、备受追捧，誉为美声最高境界的真空管直热式三极管单管甲类放大器。关于它靓声的秘诀，专家道出了其中的奥秘：“我们之所以花费这样大的代价造一台单管甲类300B胆机，主要就是为了听它那丰富的偶次谐波，可以激发听感中的美丽泛音。”资深专家同时提示我们：“我们在列出单管放大所具有的特长后，也需要看到它的短处是很多的，可以说除了靓声的长处以外其他都是不足。首先是效率低，一台单管甲类放大的胆机，它的阳极效率绝不可能超过25％，若是算上灯丝和前置推动部分的耗电，则整机的效率也许只有10％……”

关键词： 组合逻辑电路   时序逻辑电路   触发器  

摘要： 触发器是时序逻辑电路的最基本的结构单元,触发器教学应该从触发器的电路结构入手,比较组合逻辑电路,分析掌握各种触发器的工作原理、逻辑功能以及内在联系。

关键词： 二次开发   图形化   电气接线图   电气计算   拓扑结构  

摘要： 提出并研究了一种以Microsoft Visio2003图形软件为平台,利用VBA宏进行二次开发的图形化电力系统计算软件的新技术和实现方法。研究了基于所绘电气接线图的电力系统通用的图形化建模方法,以及电网拓扑结构的自动识别和电气计算模块的自动连接,并实现了在Visio2003图形界面上进行实用的电力系统图形化潮流计算。研究结果表明,Visio的二次开发技术为图形化电力应用计算软件的开发提供了新的有效的途径和方法。

关键词： 10kV配电变压器   断路器   负荷开关   熔断器   保护配置  

摘要： 10kV配电变压器的保护配置主要有断路器、负荷开关或负荷开关加熔断器等。对10kV环网供电单元和终端用户10 kV配电变压器采用断路器、负荷开关加熔断器组合的保护配置方式进行技术、经济比较,供配电网的设计和运行管理部门参考。

关键词： social comparison   absolute evaluation   relative evaluation   absolute feedback   relative feedback   objective standards   behavioral measures   better-than-average effect   comparative judgment  

摘要： Which matters more-beliefs about absolute ability or ability relative to others? This study set out to compare the effects of such beliefs on satisfaction with performance, self-evaluations, and bets on future performance. In Experiment 1, undergraduate participants were told they had answered 20% correct, 80% correct, or were not given their scores on a practice test. Orthogonal to this manipulation, participants learned that their performance placed them in the 23rd percentile or 77th percentile, or they did not receive comparative feedback. Participants were then given a chance to place bets on two games-one in which they needed to get more than 50% right to double their money (absolute bet), and one in which they needed to beat more than 50% of other test-takers (comparative bet). Absolute feedback influenced comparative betting, particularly when no comparative feedback was available. Comparative feedback exerted weaker and inconsistent effects on absolute bets. Absolute feedback also had stronger (and more consistent) effects on satisfaction with performance and state self-esteem. Experiment 2 replicated these effects in a different university sample, and demonstrated that the effects emerge even when bets are placed after participants rate their satisfaction with their performance (although these ratings do not mediate the effect of feedback on bets). These findings suggest that information about one's absolute standing on a dimension may be more influential than information about comparative standing, partially supporting a key tenet of Festinger's [Festinger, L. (1954). A theory of social comparison processes. Human Relations, 7, 117-140.] theory of social comparison. (C) 2008 Elsevier Inc. All rights reserved.

关键词： 分类系统   商业的   变换   家用的   电连接器   插脚   电插头   电气安全   熔断器   工业的   作标记   性能测试   插头适配器   插座适配器  

标准号: BS 1363-5-2008

摘要： This Part of BS 1363 specifies requirements, with particular referenceto safety in normal use, for 13 A, fused, conversion plugs for household,commercial and light industrial *** scope of the standard covers two-pole plus earth conversion plugsthat are either reusable or non-reusable and that are suitable for theconnection of non-BS 1363 type plugs, conforming to a recognizedstandard, to socket-outlets conforming to BS *** scope of this standard is limited to devices with the followingcharacteristics:? that have insulating sleeves on line and neutral pins;? that have one plug portion and one set of contacts intended toconnect to a non-BS 1363 type plug that conforms to thedimensional requirements of a standard listed inIEC TR 60083;? that are suitable for the connection of electrical equipmentin a.c. circuits only, operating at voltages notexceeding 250 V r.m.s. at 50 Hz;? that may have the un-terminated metal earth pin replaced with asimilarly dimensioned insulated shutter opening device (ISOD)designed to operate the shutter mechanism of a socket-outletconforming to BS *** A metal earth pin can be brass, copper, phosphor-bronze or othermetal at least equivalent with regard to its conductivity, resistance toabrasion, and resistance to *** categories of conversion plugs are specified, covering normal andrough *** plugs specified in this standard are intended for theconnection of loads to socket outlets; they are not intended for theconnection of electrical power generators to socket *** plugs incorporating switches, transformers, thermostats,or other control means are outside the scope of this Part ofBS *** standard also does not cover:? non-BS 1363 type conversion plugs, i.e. with a contact set tofit 13 A plugs, and a male plug portion suitable for a non-BS 1363type socket outlet; or? adaptors (as to which, see BS 1363-3).