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关键词： 虚拟仪器技术   时序逻辑电路   仿真   设计型实验  

摘要： 基于虚拟仪器技术的时序逻辑,电路仿真实验平台对时序逻辑电路的基本实验进行了功能设计,同时进行了仿真过程演示。通过该平台的仿真演示,学生可直观地观察到时序逻辑电路的功能和运行状态的变化,该平台具有操作简单的优点。该平台的设计方法,是将学生引入"设计型实验"的一种有效途径。

关键词： 直流空气断路器   重击穿   静电场   仿真  

摘要： 为了解决直流空气断路器的重击穿问题,本文简要分析了重击穿的基本过程和机理,阐述了电场分布因素对重击穿过程的重要影响,并提出了一种通过静电场计算来分析和预测断路器重击穿及其发生位置的方法,为抑制断路器的重击穿,提高空气直流断路器的性能和可靠性提供了帮助。

关键词： 变分模态分解   瞬时频率   熔断器   故障分析  

摘要： 非短路损坏故障不但增加车辆运营经济成本,而且影响运营线路的运营计划。该文针对熔断器非短路故障频发的地铁车辆,基于NI作为检测硬件设计一套故障诊断测试系统,并应用Dasylab软件搭建系统的采集部分,通过对列车运营时段的测试数据进行整体统计分析,应用VMD剔除趋势项,对偏离均值的异常数据应用VMD分析,最终找到熔断器非短路故障频发原因。结果表明,该文所设计的故障诊断测试系统与分析方法是有效并可靠的,可为工程实用提供参考。

关键词： 三相电动机   电气火灾   导线连接   接触电阻   消防安全   电火花   过负荷   保险丝   电气设备   可燃物   熔断器   短路电流   火灾事故   配电线路  

摘要： 目前在我国发生的火灾中,有半数以上属于电气火灾。据权威数据表明,电气火灾造成的财产损失占火灾总损失的70%以上。由此可见,消灭电气火灾应毋庸置疑地摆在企业消防安全的首要地位。特别是作为电力企业的工作人员,一方面要建立健全消防组织机构,广泛进行消灭电气火灾的宣传活动,增强安全意识;另一方面更要以义不容辞的职责,严格按照'以防为主,防消结合'的方针,落实各种制度,严守安全规范。

关键词： 站用变   高压熔断器   电压互感器  

摘要： 近几个月来,在我们所管辖的49座变电站中,连续出现几次电压互感器高压熔断器两相以上熔断的故障,有的变电运维人员在未经检修人员试验的情况下,就盲目恢复送电,虽然侥幸没有造成事故,但这与我们公司的管理是相矛盾的。分析原因,主要是由于不知道或不懂得电压互感器、站用变不做试验就送电所造成的危害。

关键词： 电子技术   集成运算放大电路   虚短、虚断  

摘要： 本文主要讲述高职教育电子技术课堂教学中集成运算放大电路"虚短"和"虚断"的概念。首先,讲述"虚短"和"虚断"的基本概念;然后,结合放大电路基本理论,以典型集成运算放电路线性应用为例进行论述,得出集成运算放大电路"虚短"和"虚断"的结论;最后,对本文进行总结,简述集成运算放大电路"虚短"和"虚断"的概念,简要介绍"虚短"和"虚断"的概念在课堂教学中的基本注意事项。

关键词： Adaptive comparative judgment   Middle school   Design   Design assessment   Formative assessment  

摘要： While design-based pedagogies have increasingly been emphasized, the assessment of design projects remains difficult due to the large number of potentially correct solutions. Adaptive comparative judgment (ACJ), an approach based on assessors/judges working through a series of paired comparisons and selecting the better of two items, has demonstrated high levels of inter-rater reliability with design projects. Efforts towards using ACJ for assessing design have largely centered on summative assessment. However, evidence suggests that ACJ may be a powerful tool for formative assessment and design learning when undertaken by students. Therefore, this study investigated middle school students participated in ACJ at the midpoint and conclusion of a design project, both receiving and providing feedback to/from their peers through the ACJ process. Findings demonstrated promise for using ACJ, as a formative assessment and feedback tool, to improve student learning and achievement.

关键词： 电气系统   电子系统   保护曲线   断路器   熔断器  

摘要： 民用建筑电气设计中,不同设计人员之间、设计人与审图人之间对电通保护器SPD的设置、设置地点及试验形式经常产生不同意见,现在国内外生产SPD厂家也在陆续推出SPD的专用后备保护,之中对是否有此必要进行了探讨。

关键词： Rat   Cognitive bias   Feedback sensitivity   Antidepressant   Cognitive flexibility   Behavioural   Probabilistic reversal learning   Ambiguous-cue interpretation  

摘要： Depressive disorders are often associated with cognitive biases. In this study, we investigated, in an animal model, whether cognitive judgement bias, measured as a stable and enduring behavioural trait, could modulate the effects of antidepressant drugs on other cognitive processes associated with depression. For this purpose, we identified rats displaying 'pessimistic' and 'optimistic' traits in a series of ambiguous-cue interpretation (ACI) tests. Subsequently, in the preclinical version of the probabilistic reversal-learning (PRL) test, allowing multiple reversals within a test session, we compared the effects of acute administration of 5 different antidepressant (AD) drugs (agomelatine, escitalopram, clomipramine, mirtazapine and venlafaxine) on cognitive flexibility and sensitivity to positive/negative feedback in optimistic and pessimistic animals. We report that, following acute treatment with agomelatine, the proportion of lose-shift behaviours in the PRL test was significantly reduced in pessimistic animals compared to optimists. We also demonstrate that acute treatment with another antidepressant drug, mirtazapine, significantly increased the sensitivity of rats to positive feedback, as indexed by the increased proportion of win-stay behaviour following probabilistic reward. This effect was independent of cognitive bias and was associated with a reduced number of reversals made by the animals. Three other tested drugs had no significant effects on behavioural measures assessed in our study.

关键词： 射频功率发生器   E类功率放大电路   PID控制  

摘要： 系统地研究了E类功率放大电路,通过选择适当的器件,设计出高效简单的放大电路;初步设计了PID的控制策略,并且构建了基于E类功率放大电路的射频功率发生器。经实验测试,本射频功率发生器具有半3U尺寸,额定输出功率达到1 500 W,整机效率大于65%,功率准确度小于1%。