Contribution of uncertainty in estimation of active drag using assisted towing method in front crawl swimming

Active drag force in swimming can be calculated from a function of five different variables: swim velocity, tow velocity, belt force, power output and exponent of velocity. The accuracy of the drag force value is dependent on the accuracy of each variable, and on the contribution of each variable to drag estimation. To calculate uncertainty in drag value, first the derivatives of the active drag equation with respect to each variable were obtained. Second, these were multiplied by the uncertainty of that variable. Twelve national age and open level swimmers were recruited to complete four free swimming and five active drag trials. The uncertainties for the free and the tow swim velocities, and for the belt force, contributed approximately 5–6% and 2–3% error, respectively, in calculation of drag. The result of the uncertainty of the velocity exponent (1.8–2.6) indicated a contribution of about 6% error in active drag. The contribution of unequal power output showed that if a power changed 7.5% between conditions, it would lead to about 30% error in calculated drag. Consequently, if a swimmer did not maintain constant power output between conditions, there would be substantial errors in the calculation of active drag.     

Taking active learning into the primary school: a matter of new practices?

This paper examines the extension of active learning pedagogical practices familiar in preschool settings to the first class of primary school. Policy and practice guidance in the UK is advocating the benefits of experiential learning as a way of engaging young children as they move into primary school but for teachers this means a move to new practices which can be in tension with other expectations. In this paper, the rationale for active learning is considered along with an account of the classroom activities of teachers and children in five primary schools that were implementing the policy shift to active learning. The children in these classes spent varying amounts of time in whole class activities led by the teacher or in small groups directed to engage with specific activities. They had opportunities to engage and respond verbally, through manipulating objects and with physical actions but the emphasis was on planned, teacher-directed learning activities. The characteristics of active learning as introduced in these innovative classes are compared with the expectations of practice guidance and theorising about early learning.     

基于遗传算法的网络拥塞控制新策略

推导了基于流体流理论的网络简化模型,并基于该模型将遗传算法应用于PID控制器参数优化,定义了一个综合调节时间、上升时间、超调量、系统误差等动静态性能指标函数,在给定的参数空间进行组合优化搜索,迅速求得使性能指标优化函数极小化的一组PID控制器参数,而将PID控制器应用于网络主动队列管理系统中。仿真结果表明,在大时滞和突发业务流的冲击两种情况下,该方法设计的控制器的动静态性能优于RED、PI算法。     

The Role of Parents and Community in the Education of the Japanese Child

In Japan, there has been an increased concern about family and community participation in the childs education. Traditionally, the role of parents and community in Japan has been one of support and less one of active involvement in school learning. Since the government commenced education reforms in the last quarter of the 20th century, a more active role for parents and the community in education has been encouraged. These reforms have been inspired by the need to tackle various problems that had arisen, such as the perceived harmful elements of societys preoccupation with academic achievement and the problematic behavior of young people. In this paper, the following issues are examined: (1) education policy and reform measures with regard to parent and community involvement in the childs education; (2) the state of parent and community involvement at the eve of the 20th century.     

李德“左”倾军事路线的危害及其形成根源

李德采用左倾军事路线,直接指挥了第五次反围剿,造成中央根据地丢失,红军损失过半的严重后果,危害严重,其错误军事路线的形成有其主观因素,也有客观原因。对第五次反围剿的失败,李德负有理大责任。     

激发学生主动思考的无机化学实验教学方法

为了在无机化学实验教学中培养学生批判性思维能力,通过合理安排实验顺序、加大实验的综合化程度、把实验步骤进行模糊化处理、让学生按照已有知识独立设计实验步骤等一系列改革措施,激发了学生在无机化学实验教学过程中主动思考,拓展了学生的思维跨度和深度,取得良好的教学效果。     

中职校学生数学学习的“活性评价”简

针对中等职业教育兼有的升学和就业双重功能,和有不同专业对于数学不同的需求。中等职业学校数学学习“活性评价”是一项重要的教学实验,行动研究实践证明,中等职业学校学生数学学习“活性评价”切实可行,在数学学习“活性评价”中设置评价情境及问题情境;评价过程动态化、常态化;评价内容、形式、标准、权重灵活化;评价内容多元化;评价主体多元化;评价具有诊断、发展和激励的功能。     

中国女排与世界女排强队主动得分的比较及其制胜因素分析

每球得分制规则的实施将比赛得分因素客观的划分为两个得分系统、6个得分技术环节。通过分析发现中国女排利用每球得分制规则带来的机遇扬长避短,在实战中已见成效;在后排攻的运用与得分能力与世界女排强队存在较大差距;在连续防反能力上也有待于进一步提高。中国女排的快速多变特点在接发球进攻中、快速反攻能力在发后反中、连续防反能力在接后反中能有高水平的发挥,是中国女排的主要制胜因素。     

Making Learning Active with Interactive Whiteboards,Podcasts, and Digital Storytelling in ELL Classrooms

The purpose of this study was to examine effective ways to integrate an interactive whiteboard, podcast, and digital storytelling for language proficiency development in English language learners. Researchers integrated these three technologies into a 60-hour intensive summer English program and investigated their impacts on student vocabulary skill development. Researchers collected multiple data including daily video podcasts, vocabulary tests, a student survey, Photostory videos, and a teacher interview. The results showed that using an interactive whiteboard for (a) visual presentations, (b) interactive games, and (c) test reviews was useful for the English language learners to learn new vocabulary and engage in learning. The effects of a digital storytelling project and the video podcasts are also discussed.     

英语教学中如何激发学生课堂参与意识——以集宁师范学院《新视野大学英语》教学为例

学生在教学中处于主体地位,英语教师应以学生为中心,采取多种教学手段激发学生学英语的兴趣,并优化课堂教学。课堂上,要不断激发学生的课堂参与意识,让学生从听众成为参与者,培养学生运用外语进行交际的能力。该文通过分析影响学生课堂参与的主要因素,提出改进学生课堂参与的教学策略。