滑板运动和冲浪运动中的动力学模型的特性

研究了滑板运动和冲浪运动中动力学模型的特性,即在光滑圆滚线上和粗糙圆滚线上的滑板,在竖直平面内,同一水平线上经过一个最低点的 任意两点所有光滑连接线中;物体无初速度滑动时,所需时间最短的曲线是圆滚线（最速降线）这一特性对目前国际上滑板运动和冲浪运动具有指导性的意义。     

品味经典——滑板运动

滑板运动被称为最酷的运动。这项运动可谓是极限运动的鼻祖了,许多极限运动项目都是由滑板运动延伸而来的。而滑板运动却是由冲浪运动演变而来的。20世纪50年代初,当时美国西海岸是弄潮儿们大试身手的地方,人们用木制的冲浪板在风口浪尖上寻找乐趣。为了能够在陆地上安全地练习冲浪,有人在木板下安装上了铁轮子,这个简朴的运动器械竟然也能带给人冲浪时的激情,而且不受季节、     

滑板运动：勇敢者的最爱

滑板运动起源于上世纪60年代初的美国,由海上冲浪运动演变而来。 滑板运动集冲浪、滑雪的特点于一身,它的冲大跳台、探角、翻转等动作很像滑雪,而其掌握平衡的技巧又很像冲浪。     

滑板

滑板项目可谓是极限运动鼻祖,许多的极限运动项目均由滑板项目延伸而来,20世纪50年代末60年代初由冲浪运动演变而成的滑板运动,在而今已成为地球上最“酷”的运动。     

美国的"滑板"运动

美国的“滑板”(skateboard)作为一种游戏首创于1961年。据说,当时在加利福尼亚海滨的一群冲浪好手要举行冲浪比赛,但因海潮时涨时退,比赛中断了好几次。在比赛的间隙,他们百无聊赖,突发奇想地制作了一种带轮子的、狭长的、滑浪式的陆地滑板,以便在陆地上也能过过“滑瘾”。“滑板”的许多动作既像滑冰,又像冲浪,所以它又有一个英语别名———skurfing,这是由skating(滑冰,溜冰)和surfing(冲浪)混合而成,意即陆地“冲浪”。自20世纪70年代初开始,滑板运动在美国广泛流行开来。不久,“滑板”又发展成一个体育竞赛项目,难度越来越大,有倒立滑…     

关于滑板动力的力学原理

20世纪60年代初,滑板运动起源于美国,由海上冲浪运动演化而来,是水上滑板运动在陆地上的延伸.冲浪运动受地理和气候条件的限制,而滑板运动则有更大的自由度.滑板运动是     

滑板酷运动

滑板的历史 第一代滑板至今看来仍是一项古朴的发明：将一块50厘米×50厘米的木板固定在轮滑的铁轮子上。即使这样一个简单的运动器械,但由于它能提供冲浪给人带来的同样的心理感受,也还是引起了人们的足够兴趣。     

滑板也疯狂

如今,越来越多的人喜欢上了极限运动,惊险、刺激。滑板项目可谓是极限运动的鼻祖,20世纪50年代末60年代初,由冲浪运动演变而成的滑板运动,如今已成为地球上最“酷”的运动之一。许多项目均由滑板项目衍生而来。     

手指滑板 行云流水的指尖魔法

<正>20世纪50年代末期,出于对冲浪运动的热爱,一些冲浪爱好者按捺不住内心的悸动,冲破水的束缚,将冲浪运动带上陆地,有谁能想到,这个仅仅因为玩闹而做出的举动,竟然能够衍生为时下风靡全球的街头运动——滑板。后来,一位滑板爱好者出于对这项运动的热爱,为了不受天气条件的限制,他想出了手指滑板这一形式,以手指来替代双脚,磨炼自己的滑板技术。     

质点沿圆滚线运动的角速度

本文讨论了质点沿圆滚线运动时的角速度的变化规律,指出了■等于常数的条件.     

Disability,Riding, and Identity: A Qualitative Study on the Influence of Riding on the Identity Construction of People with Disabilities

Semi-structured face-to-face interviews were used to examine the influence of riding on the identity construction of people with disabilities. The 15 participants, three men and 12 women, were between 15 and 65 years old and have various physical disabilities. The data analysis derives from identity theory, a social–psychological theory that understands identity as an interaction between the individual and society. The findings show that: the informants either acquire a new identity as a rider or they resume with the rider identity they had before their illness or accident; riding offers a link to their previous lives; and riding helps to focus on what the informants can do, and not, as this group is often viewed by society, on what they cannot do. The findings thus show that riding can influence the identity construction of people with disabilities.     

Load on Bicycle Frame During Cycling with Different Speeds and Gestures

Experiment and dynamic simulation were combined to obtain the loads on bicycle frame. A dynamic model of body-bicycle system was built in ADAMS. Then the body gestures under different riding conditions were captured by a motion analysis system. Dynamic simulation was carried out after the data of body motions were input into the simulation system in ADAMS and a series of loads that the body applied on head tube, seat pillar and bottom bracket were obtained. The results show that the loads on frame and their distribution are apparently different under various riding conditions. Finally, finite element analysis was done in ANSYS, which showed that the stress and its distribution on frame were apparently different when the frame was loaded according to the bicycle testing standard and simulation respectively. An efficient way to obtain load on bicycle frame accurately was proposed, which is significant for the safety of cycling and will also be the basis for the bicycle design of digitalization, lightening and customization.     

英语感叹词会话语用理据探析

英语感叹词是一种表达情感和意愿的不变化词类。用作人们对周围刺激和谈话对方的言语信息的一种反应。感叹词在语义学中的意义只能体现其语法结构的实际表述,而只有在语用学中的语境意义才能体现其实际会话用途。说话者正是本着语用的目的在使用这些感叹词。该文从语用学的角度认识感叹词,并结合具体语料分析感叹词在不同语境中对会话话语基调的体现。     

陶行知师范教育思想及其意义

师范教育思想是陶行知先生教育理论体系的重要组成部分 ,他认为师范教育是“兴邦”、“立国”之大事。据此他提出了“广义的师范教育”思想 ,并且认为从改革乡村师范教育入手 ,推动全民族的教育发展是发展生产师范教育的重要立足点。     

Outcomes of Home-Support Consultation on the Maintenance of Bicycle-Riding Skills for Youth With Autism Spectrum Disorder

Bicycle riding is a functional motor skill that increases physical activity opportunities, social interaction, and independence. However, bicycle riding is difficult for youth with autism spectrum disorder (ASD) to learn. This study examined the effectiveness of home-support consultation (HSC) on increasing the maintenance of independent bicycle riding following initial skill acquisition. Fifty-one youth with a confirmed ASD diagnosis learned to ride a two-wheeled bicycle during a training camp. Twenty-nine riders enrolled in a HSC intervention to promote distributed practice of the learned skill. The control cohort (N = 22) was exempt from the HSC intervention. One year following initial skill acquisition, 62.07% of the HSC cohort compared to 36.36% of the control cohort still reportedly displayed the skill. Within the HSC cohort, riders who reported at least 8 weeks of practice following acquisition on average maintained the skill. Implications of home consultation are discussed.     

新型摩擦实验装置的研制与应用

介绍了一种新型摩擦实验装置的工作原理、性能和实验结果。该装置设计为滑板转动的传动机构,由转动轴带动滑板转动来调节滑板的倾角,倾角达0°~50°的任意角度。滑板倾角调整分为电动机带动的快速调整和用手动微调2种。该实验装置可以用来测定2种材料之间的静、动摩擦系数,并可以进行一定角度滑板上的物体滑动、翻倒、滚动的演示。实验结果表明,所研制的实验装置具有较好的实验性和可靠性。     

Dynamic response analysis of a moored crane-ship with a flexible boom

The dynamic response of moored crane-ship is studied. Governing equations for the dynamic response of a crane-ship coupled with the pendulum motion of the payload are derived based on Lagrange＇s equations. The boom is modeled based on finite element method, while the payload is modeled as a planar pendulum of point mass. The dynamic response was studied using numerical method. The calculation results show that the large-amplitude responses occur at wave periods near the natural period of the payload. Load swing angle is smaller for crane-ship with flexible boom, in comparison with rigid boom. The ship surge motions have large vibrations for crane-ship with flexible boom, which were not observed for a rigid boom. The analysis identifies the significance of key parameters and reveals how the system design can be adjusted to avoid critical conditions.     

PowerPoint slide provision and student performance: the moderating roles of self-efficacy and gender

Research on the pedagogical value of providing students with PowerPoint (PPT) slide handouts has produced mixed results. One reason for the inconsistent findings may be that most studies in this stream of research have neglected to examine individual differences. In the current study, we aimed to advance research on the pedagogical value of providing students with access to PPT slide handouts by examining whether self-efficacy and gender influence the effect of PPT slide provision on academic performance. We found no evidence to suggest that the provision of slide handouts has broad, unconditional pedagogical value. Instead, we found that both self-efficacy and gender moderated the extent to which the availability of the handouts enhanced or hindered students’ performance. As predicted, both students high on self-efficacy and males performed significantly better when they were provided with handouts. Conversely, students low on self-efficacy performed significantly worse when the handouts were provided. Female students also trended toward lower performance when the handouts were provided. Additionally, we found that students who were provided with PPT handouts perceived their instructor as more effective, and that this relation was mediated by students’ feeling of preparation. Finally, students also considered the provision of PPT handouts more valuable to their learning and course performance than one-to-one interactions with the professor. Implications for research and practice are discussed.     

双曲运动群的单参数子群及其轨道

本文通过研究双曲平面H~2上运动群的单参数子群及其分类,单参数子群的轨道曲线的几何性质,得到如下主要结果:定理1 双曲平面H~2上运动群G的单参数子群就是H~2上的旋转群,或平移群,或平行位移群;反之亦然.定理2 在双曲平面H~2上,运动群G的单参数子群的每个轨道或是一个点,或是一条常(测地)曲率曲线.其逆亦真.     

Preventing a summer slide in reading – the effects of a summer school

ABSTRACT

Researchers have found that summer reading loss contributes to the reading achievement gap between low and high socioeconomic (SES) children. This study aimed to examine the effectiveness of a 3-week summer intervention in addressing this slide for 36 low SES children compared with another 36 children in a matched control group from one New Zealand school. The program involved one-to-one tutoring with explicit phonics instruction, high-frequency word-reading practice and application of these skills in reading age-appropriate texts. Results showed that although the mean reading comprehension slide was 5.8 months for both groups, the summer school group had higher word reading scores than the control group. The summer school participants showed improvements in phonological recoding ability, word reading, spelling and passage reading accuracy. These were not sufficient to stop the reading comprehension slide, but the program did make inroads. With further emphasis on comprehension strategies, the achievement gap may narrow.