新型单足式纵弯复合模态直线超声电机的设计

提出了一种新型结构的直线超声电机,对其驱动原理进行了简要分析;利用有限元软件ANSYS对复合振子进行模态分析和谐波响应分析,计算出复合振子结构尺寸改变对其一阶纵向伸缩和二阶弯曲振动模态频率的影响,得出了两模态频率对结构参数的相对灵敏度;有限元分析结果为复合振子的结构优化设计和电机输出性能的预估提供了有益的参考,据此设计出符合模态简并的复合振子结构及电机的总体结构.     

Fine Motor Control is Related to Cognitive Control in Adolescents with Down Syndrome

The connection between human cognitive development and motor functioning has been systematically examined in many typical and atypical populations; however, only a few studies focus on people with Down syndrome (DS). Twelve adolescents with DS participated and their cognitive control, measured by the Corsi-Block tapping test (e.g., visual working memory), the Auditory Memory span test (e.g., verbal working memory) and the Tower of London test (e.g., cognitive planning), and motor control, measured by the Purdue Pegboard (e.g., fine motor control), were measured in this study. Results indicate that if people with DS have better performance in fine manual dexterity, they will have better performance in cognitive planning and verbal working memory abilities. The co-activation hypothesis of the prefrontal area and the cerebellum may support this positive relationship. Hence, it is suggested people with DS will obtain benefits in cognitive control by participating in further motor intervention.     

风光互补发电系统最大功率跟踪实现电路的研究

本文介绍了风光互补发电系统的构成,对发电系统最大功率跟踪问题进行了分析,研究了一种双输入DC/DC变换器的实现电路,研究结果表明该电路能很好的应用于风光互补发电系统,具有较高的实用价值。     

Indicators of sailing performance in youth dinghy sailing

Abstract

This study aimed to determine indicators of sailing performance in 2 (age) groups of youth sailors by investigating the anthropometric, physical and motor coordination differences and factors discriminating between elite and non-elite male optimist sailors and young dynamic hikers. Anthropometric measurements from 23 optimist sailors (mean ± SD age = 12.3 ± 1.4 years) and 24 dynamic youth hikers (i.e. Laser 4.7, Laser radial and Europe sailors <18 years who have to sail the boat in a very dynamic manner, due to a high sailor to yacht weight ratio) (mean ± SD age = 16.5 ± 1.6 years) were conducted. They performed a physical fitness test battery (EUROFIT), motor coordination test battery (Körperkoordinationstest für Kinder) and the Bucket test. Both groups of sailors were divided into two subgroups (i.e. elites and non-elites) based on sailing expertise. The significant differences, taking biological maturation into account and factors discriminating between elite and non-elite optimist sailors and dynamic hikers were explored by means of multivariate analysis of covariance and discriminant analysis, respectively. The main results indicated that 100.0% of elite optimist sailors and 88.9% of elite dynamic hikers could be correctly classified by means of two motor coordination tests (i.e. side step and side jump) and Bucket test, respectively. As such, strength- and speed-oriented motor coordination and isometric knee-extension strength endurance can be identified as indicators of sailing performance in young optimist and dynamic youth sailors, respectively. Therefore, we emphasise the importance of motor coordination skill training in optimist sailors (<15 years) and maximum strength training later on (>15 years) in order to increase their isometric knee-extension strength endurance.     

DC steady-states analysis of lossy uniform transmission lines

1 Introduction In the past 20 years with the rapid development of VLSI (very large scale integration) circuits and continual spread of electric power system scale, theories on transmission lines have become an important research field where finding the analytic solutions to lossy transmission line equations remains a tough nut. Since the mathematical tool cannot provide effective help, there is no universal method to solve transmission line equations [1]. A number of researchers have obtaine…     

大学生涉跑猝死事件的体医融合防卫机制研究

近年来,大学生身体素质不佳,已成为"老大难",也是刻不容缓需要解决的问题,多地曾出现在体测、运动会、马拉松中晕倒甚至猝死事件,这给学校体育工作的开展带来不小的考验。带着因涉跑引起猝死的疑问,通过猝死案例分析,探究高校大学生猝死的病理学的非运动成因。研究认为：涉跑猝死的主因是先天性生理疾病,运动不是引发猝死的主要诱因,并提出了预防运动猝死的"堵疏结合"的医学监控策略和体医融合防卫机制构建方法。建议通过入校时医学筛查、跑前医学检查、跑中医学观察、猝死现场急救、跑后跟踪复查降低猝死风险;建立宿舍、运动场地、运动项目的全覆盖的心脏复苏志愿队伍,实施"黄金8分钟"内的急救生存链;建立学生、学校、政府、社会四方体育运动分级分类保险制度,从风险转移和人道主义援助进行关怀;建立涉跑猝死、猝死、非正常死亡的数据库,开展非正常死亡人员的病理学研究;建立全生命周期医学监控和健康安全宣传教育,形成全方位、全过程、全人员的体医融合防卫机制。     

儿童早期发展与教育中的动作和运动问题——四论进化、发展和儿童早期教育

随着《国家中长期教育改革与发展规划纲要(2010-2020)》等一系列教育政策文件的颁布,学前教育如何遵循幼儿成长规律和学前教育规律,回归基本成为值得再次关注的重大问题。什么是儿童早期发展与教育的基本,如何认识基本,是需要学前教育理论研究界深入思考的。儿童早期的动作发展不仅是其智力发展的重要指标,更是发展的普遍特征;运动是以身体为轴心的一种综合性的、多方面的和总体的活动,涉及认知、动机以及情感方面。动作和运动在儿童早期发展与教育中具有重要地位。从种系发生和个体发生角度来说,动作和运动(同时还包括感觉)在婴幼儿期心理的发展中起着积极的建构作用。从动作技能与智力技能的同源性来看,动作问题一开始就并不单纯是动作问题,动作发展本身是儿童早期心理发展的重要组成部分,同时也是其早期心理发展的主要建构力量。对儿童早期动作和运动的研究具有重大的生物学、人类学、心理学和教育学意义。遗憾的是,儿童早期动作发展和运动的重要性并未引起足够的重视。过分强调抽象符号系统的作用,特别是把抽象符号系统和学业学习在儿童早期发展中的作用置于一个极不恰当的位置是当前早期教育实践中极为普遍存在、也是非常危险的倾向。这种危险在于以所谓早期智力开发的名...     

控制周期时间指标的方法在高栏训练中的应用

通过实验训练 ,阐述控制周期时间指标的训练方法对于提高 110m高栏栏间节奏能力的作用 ,并从理论角度给予检测及分析     

The relative age effect in the German Football TID Programme: Biases in motor performance diagnostics and effects on single motor abilities and skills in groups of selected players

Abstract

This study examined the disturbing effects of relative age on the talent identification process in the talent development programme of the German Football Association. The bias in the selection rate was examined via the extent of relative age effects. The bias in motor performance diagnostics was analysed by comparing the motor performance of selected players with normal motor development. The mechanisms underlying the relative age biases in motor performance were examined by modelling the direct and indirect effects of relative age on single motor performance tests for sprint, running agility, dribbling and ball passing and control. Data from 10,130 selected football players from the U12 to U15 age groups were collected in autumn 2010. The birth distribution differed significantly from the reference population with approximately 61% of the players born in the first half of the year. The selection probability was approximately two times higher for players born in the first quarter of the year than for players born in the last quarter. Revised motor performance diagnostics showed better results on average for relatively younger players. Path analysis revealed significant direct and indirect relative age effects for physiologically demanding tests and almost no effects for technically demanding tests. Large sample sizes allowed high resolution in relative age with additional informational content and multivariate modelling of the complex relationships among relative age, physical development and motor performance. The results are discussed on how relative age affects the effectiveness and fairness of talent identification and development processes.     

运动技能的内隐学习与分心练习——对应激的抵御

为抵御应激对运动技能水平发挥的影响 ,研究以轨迹追踪任务为实验范式 ,将 32名被试分 4组在不同条件下进行为期 12 d的练习 ,并比较了各组在两种应激条件下的测试结果。结果显示 :对于复杂的操作任务 ,内隐学习比外显学习更有效。分心练习所获得运动技能较少受高应激的影响