电力变压器离线局部放电测量试验中的容升现象分析     

王烜  曹晓珑  李云阁  刘英 《上海大学学报(英文版)》2007,11(5):490-495

Partial discharge test on a transformer is carried out according to the items in IEC 60.During the test,unproved measuring system is calibrated by proved system at a voltage no less than 50% the rated testing voltage.The result is then extrapolated linearly,leading to an error related to the distribution of stray capacitance,which varies with the testing frequency,especially to large transformers.In this paper a factor,named the capacitive rise fact,is introduced to assess the rise.The factor can be adjusted to some extent by changing the reactance that is connected to the LV side of the testing circuit to lower the capacity of the power source.However,the factor changes when the voltage divider on the high voltage side is removed after the voltage ratio has been calculated,and a great error is resulted under unfavorable conditions.  相似文献   

Physical activity profiles and selected muscular fitness variables in English schoolchildren: A north–south divide?     

Lee Ingle  Ashlie Stephenson  Gavin R. Sandercock 《European Journal of Sport Science》2016,16(8):1187-1196

The aim of the study was to compare and contrast habitual physical activity (PA) profiles and muscular fitness in schoolchildren from northern and southern regions of England. Data were collected from two secondary schools in the north east (NE) of England. The study procedures followed methods employed by the East of England Healthy Hearts Study in 10–16-year-old boys and girls based in the south east (SE) region of England and data were compared. Habitual physical activity (PAQ-A), vertical jump test, and hand-grip (HG) strength were assessed. We converted raw scores from all assessments to age- and sex-normalised z-scores. We recruited 597 children (58% boys) in the NE and compared findings to 597 age- and sex-matched boys and girls from the SE. Boys in the SE had significantly stronger HG scores, jumped higher, were more powerful (mean peak power: 2131?W vs. 1782?W; P?P?P?相似文献   

高职院校校内英语测试的思考     

黄彩燕 《闽西职业技术学院学报》2007,9(1):111-114

测试是衡量学生掌握语言的能力的手段。目前高职院校校内的英语测试存在着一定的缺陷,制约了学生的英语实际应用能力的培养。只有对院校内的英语测试模式进行完善,才能真正测试出学生的实际应用能力,才能对学生实际应用能力的培养起到促进的作用。  相似文献   

EWB在《电路分析》课程教学中的应用   总被引：1，自引：1，他引：1  

张红斌 《重庆职业技术学院学报》2004,13(4):40-41

电路分析是一门很重要的专业基础课,而利用EWB软件进行教学及模拟实验仿真可以提高学生的学习兴趣,让学生更直观的掌握电路分析的基本理论,更有利于培养学生的实践技能和创新能力,本文就如何在<电路分析>课程教学中应用EWB软件辅助教学进行探讨.  相似文献   

关于艺术院校学生普通话水平测试的几点思考     

刘惠彬 《新疆师范大学学报(哲学社会科学版)》2006,27(2):169-171

艺术院校的学生,特别是有专门台词课、表演课的影视表演、播音主持专业的艺术类学生,普通话水平测试的结果并不理想,达到一级水平的学生并不多。有的学生甚至怀疑普通话水平测试的信度和效度。文章针对这种情况,从口语的吐字归音入手,通过对台词教学与普通话水平测试的评价标准和要求的分析提出应试者(学生)要端正认识,掌握标准。参加普通话水平测试要按照普通话的标准说普通话,注意吐字归音从“神似”回归到“形似”。要经过严格的正音训练或参加普通话培训,在辅导老师的指导下,对自己准确定位,认真练习准备,建立起真实的自信,以顺利地通过普通话水平测试,进入“形”“神”兼备的语言艺术境界。  相似文献   

高考英语的期望后效与实际后效——基于短文改错题的调查   总被引：3，自引：0，他引：3  

QI Lu-xia 《课程.教材.教法》2007,(10)

考试对教学的影响(即考试后效)是教育界的一个热门话题,也是考试人员及考试决策人在改革考试时不能忽视的问题。近年来,越来越多省份实行自主命题,更新题型的趋势明显,但对题型后效的调查研究却未及时跟进。作者针对高考英语试卷中的英语短文改错题,在3个省的中学开展抽样调查,发现该题的期望后效与实际后效不符。调查表明,高考英语的题型有进一步改革的必要,但改动现有题型应该经过充分的论证和系统的调查,在确保高考公平公正性的前提下进行。  相似文献   

论利用入侵检测保护路由基础结构免遭拒绝服务     

伍爱华 《湖南第一师范学报》2005,5(4):113-115

当网络遭受拒绝服务时，信息包不能到达目的地：已有的路由协议不能很好地解决拒绝服务的问题。本文提出了路由基础结构拒绝服务的模型，同时描述了用入侵检测保护路由基础结构免遭拒绝服务的方法。  相似文献   

基于两个GFSRG的组合随机数发生器     

张广强  王文超 《商丘师范学院学报》2006,22(5):54-56

随机数是蒙特卡罗(Monte Carlo)方法的关键因素.首先给出一种广义反馈位移寄存器发生器及其缺点,然后在此基础上提出一种基于两个广义反馈位移寄存器方法的组合随机数发生器,最后给出一些严密的统计检验,结果证明这种组合随机数发生器不失为一种较好的随机数发生器.  相似文献   

谈历史学科应用能力的测试目标     

童和刚 《沈阳教育学院学报》2002,4(3):75-77

应用能力是文科综合测试中较高层次的能力要求，历史学科的应用能力测试目标主要包括基本观点，主体能力和现代意识等。  相似文献   

Students with special educational needs within PISA     

Barbara W. LeRoy  Preethy Samuel  Marcella Deluca  Peter Evans 《Assessment in Education: Principles, Policy & Practice》2019,26(4):386-396

Abstract

Since 2003, the Programme for International Student Assessment (PISA) has included students with special educational needs (SEN), identified as those with functional disabilities, those with cognitive/behavioural/emotional disabilities and those with limited test language proficiency. While the number of countries and included students has increased with each test administration, the percentage of students with SEN remains extremely low. The inclusion of these students is not an intentional PISA design parameter but rather a response to the interaction between the need to maintain strict sampling criteria and country-level educational mandates to include SEN students in standardised testing. Based on the analysis of student participation and performance across four cycles of PISA (2003–2012), this paper examines the challenges that exist in current PISA procedures related to: student sampling, eligibility and identification; assessment methodology; and reporting results. PISA practices, their limitations for scientific inferences and recommendations for design improvements are given.  相似文献