电力变压器离线局部放电测量试验中的容升现象分析

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.     

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

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

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。     

EWB在《电路分析》课程教学中的应用

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.     

用热力学浅析几个“反常”问题

通过对化学几个“反常”问题的浅析,说明热力学是一种非常有用的理论工具.     

论利用入侵检测保护路由基础结构免遭拒绝服务

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。     

基于两个GFSRG的组合随机数发生器

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.     

Students with special educational needs within PISA

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.     

非对称损失下单边截断分布族参数的经验Bayes检验及其收敛速度

在一种非对称损失下,构造了一类单边截断型分布族参数的经验Bayes检验,建立其收敛速度,在一定条件下证明了它的收敛速度可以任意接近于1/2。最后给出满足定理条件的一个例子。     

医学院校教改课题成果推广应用的现状调查与管理对策研究

为了解教改课题成果推广的现状,对广西医科大学相关教学管理人员及教师进行访谈和问卷调查。结果显示教改课题研究内容脱离教学实际需要、不懂相关推广渠道、无相应经费支持等严重制约了成果的推广。为此,提出对教改立项课题研究进行全过程管理、加强成果推广应用的指导和宣传、健全完善教改课题相关管理制度等对策。