优秀青少年游泳运动员蹲踞式与抓台式游泳出发技术的对比分析     

童超益  郭海英  周喆啸  李建设 《浙江体育科学》2020,(1):106-112

目的:基于青少年的生理特点,通过对比青少年游泳运动员采用蹲踞式和抓台式2种游泳出发技术时的运动学和动力学数据,以期为青少年游泳运动员的运动训练与比赛提供参考。方法:使用Kistler测力台和高速摄像机记录从青少年游泳运动员从准备姿势到入水的整个过程,通过对2种游泳出发技术参数的统计对比分析,总结这2种游泳出发技术的特点。结果:从游泳出发技术上来看,男性采用蹲踞式的加速蹬伸时间、地面反作用力峰值、腾空时间、腾空距离、平均水平腾空速度、出发总时间大于抓台式,而入水角度较小;女性采用蹲踞式的加速蹬伸时间、地面反作用力峰值、腾空距离、平均水平腾空速度大于抓台式,而腾空时间、入水角度、出发总时间较小。从性别角度看,男性采用蹲踞式的加速蹬伸时间、平均水平腾空速度、入水角度小于女性,而地面反作用力峰值、腾空时间、腾空距离、出发总时间较大;男性采用抓台式的加速蹬伸时间、平均水平腾空速度、入水角度小于女性,而地面反作用力峰值、腾空时间、腾空距离、出发总时间较大。结论:从游泳出发技术上来看,蹲踞式在滞台阶段加速蹬伸时间较长,但地面反作用力较大,且获得了更大的平均水平腾空速度,弥补了其滞台时间较长的缺点;在腾空阶段,在腾空时间无显著差异的情况下,蹲踞式具有明显较大的腾空距离,则蹲踞式在该阶段更具优势。从性别上来看,男性的加速蹬伸时间较小,且地面反作用力较大,但平均水平腾空速度较小,减小了男性在滞台阶段的优势;在腾空阶段,男性的腾空时间明显大于女性,但其腾空距离也较大。  相似文献   

Structural Analysis for Replicating Japanese Cultural Property Braids     

Masumi Tada  Kazuaki Yamashiro  Iwataro Oka  Akihiko Goto  Noriaki Kuwahara 《文物保护研究》2020,65(7):399-410

ABSTRACT

Historic Japanese textiles from over 1000 years ago generally show marked deterioration and only very rare examples show their original forms and much information about textile reproduction has been lost. The replication of textile braids lacks systematic methodology and is still being practiced by only few individual braiding experts. The recreation of original braids as close as possible to original braids is a part of Japan’s intangible cultural heritage. The aim of this study is to clarify the decision-making procedure through which the braiding experts can decipher the original braiding structures. As a preliminary study of this project, interviews of a braid researcher and a replicating expert, Makiko Tada were performed regarding her working practices. It is important to clarify the braiding parameters for structural analysis such as the number of transits and the balance of ridges, and it became clear that the orientation of multiple colored threads plays an important role. The expert’s replicate works were also analyzed using a text-mining statistical technique to clarify the relationship of braiding parameters. The relationship between each braiding parameter and production method such as loop manipulation and Taka-dai became clear. As a result, the process of deciphering the original braid structure has been compiled in simplified workflows, which could contribute to the standardization and improvement in efficiency of replication of cultural property braids.  相似文献   

Increased foot-stretcher height improves rowing performance: evidence from biomechanical perspectives on water     

Yang Liu  Binghong Gao  Jiru Li  Zuchang Ma  Yining Sun 《Sports biomechanics / International Society of Biomechanics in Sports》2020,19(2):168-179

Abstract

The aim of this study was to investigate whether changes on foot-stretcher height were associated with characteristics of better rowing performance. Ten male rowers performed a 200 m rowing trial at their racing rate at each of three foot-stretcher heights. A single scull was equipped with an accelerometer to collect boat acceleration, an impeller with embedded magnets to collect boat speed, specially designed gate sensors to collect gate force and angle, and a compact string potentiometer to collect leg drive length. All sensor signals were sampled at 50 Hz. A one-way repeated measures ANOVA showed that raising foot-stretcher position had a significant reduction on total gate angle and leg drive length. However, a raised foot-stretcher position had a deeper negative peak of boat acceleration at the catch, a lower boat fluctuation, a faster leg drive speed, a larger gate force for the port and starboard side separately. This could be attributed to the optimisation of the magnitude and direction of the foot force with a raised foot-stretcher position. Although there was a significant negative influence of a raised foot-stretcher position on two kinematic variables, biomechanical evidence suggested that a raised foot-stretcher position could contribute to the improvement of rowing performance.  相似文献   

旋转推铅球技术普及情况     

王鹏 《当代体育科技》2020,(12):29-30

铅球运动是一项有着几百年历程的古老的运动项目,伴随着铅球技术的快速发展,使得铅球这项运动的魅力逐渐呈现出来,作为一项关键性的铅球运动技术手段,旋转推铅球基础成为现阶段被广泛应用的一种铅球训练手段,在国内外的普及状况良好。本文就分析旋转推铅球技术在国外及国内的普及情况,并找出这种普及差异存在的成因。  相似文献   

Sex differences in elbow and wrist joint loading during the cartwheel and round off with different hand positions performed by young gymnasts     

Roman Farana  Gerda Strutzenberger  Timothy Exell  Jiri Skypala  Huw Wiltshire  Gareth Irwin 《Journal of sports sciences》2019,37(13):1449-1456

The aim of the study was to determine if sex differences exist in the key elbow and wrist joint injury risk factors during different cartwheel (CW) and round-off (RO) techniques performed by young male and female artistic gymnasts. Sixteen active young gymnasts (8 males and 8 females) performed 30 successful trials of CW and RO with three different hand positions (parallel (10), T-shape (10) and reverse (10)). Synchronised kinematic and kinetic data were collected for each trial. Two-way repeated measures ANOVA (3 × 2, technique × sex) and effect-sizes (ES) were used for statistical analysis. In conclusion, female gymnasts exhibited greater normalised peak vertical ground reaction forces (VGRF), elbow and wrist compression forces and elbow internal adduction moments during CW and RO skills compared with male gymnasts. In both sexes, the parallel and reverse techniques increased peak VGRF, elbow and wrist compression forces and the elbow internal adduction moment. Increased elbow flexion resulted in decreased peak VGRF, elbow compression forces and elbow internal adduction moment. Injury risk factors including elbow extension and internal adduction moment with axial compression force suggest that a CW and RO in reverse and parallel techniques can be hazardous especially for young female gymnasts.  相似文献   

新规则视角下男子跆拳道技战术发展趋势——以世界冠军李大勋为例     

何芸  庞俊鹏 《武汉体育学院学报》2019,53(12):82-87

文章采用文献资料法、专家访谈法、视频分析法和数理统计法，对李大勋在重大国际赛事中的交手回合、基本技术、组合技术的应用频数以及成功率等指标进行统计分析。根据2018-2019年度世界跆拳道联盟公布的最新奥运积分显示，李大勋拥有605.94个奥运积分且高于第二名将近300余分，目前世界排名第一，其技战术风格具有一定的代表性。结果显示：李大勋在比赛中习惯采用前腿侧踢与前腿横踢技术进行主动进攻、控制距离、防守破坏、封堵迎击；利用后腿横踢技术进行补充击打；灵活使用中变中、中变高等变线技术突破对手；新规则后近身贴靠时攻防转换技战术变化多样，"推+踢"技术运用巧妙，增加了其得分手段。分析认为，在实施新规则的比赛中李大勋结合判罚尺度与分值的变化，优化了进攻方式，增加了得分手段，提高了时局节奏，同时反映出现阶段跆拳道项目技战术发展趋势。  相似文献   

Back to common sense: Oxford dictionary descriptive knowledge augmentation for aspect-based sentiment analysis     

《Information processing & management》2023,60(3):103260

  相似文献   

基于微波分光仪的雷达原理模拟实验设计     

陈森  吴平  张师平 《中国现代教育装备》2011,(19):65-66

介绍了利用实验室现有微波分光仪模拟雷达基本原理的实验设计方法,具体包括微波定向传输,目标对微波的反射和散射,隐身技术。通过本实验,使学生学习和了解有关雷达的基本原理,激发学生探索科学的热情和好奇心,培养学生对现代科学技术的研究兴趣。  相似文献   

对高师开设现代教育技术课程的新思索     

王晓明 《中国现代教育装备》2011,(9):91-92,95

针对现代教育技术课程特点及教学中所存在的问题,就如何达到更好的教学效果、如何培养师范专业学生教育技术能力等,探讨了对该课程的改革,即将教学内容划分成模块,不同模块采用不同的教学策略、充分利用专题学习网站开展研究性学习、改革考核方式等。  相似文献   

浅析基于ETL技术和全表扫描哈希对比的数据同步方法     

王志学  麦晓冬  符睿 《广东轻工职业技术学院学报》2011,10(2):4-7

数据同步技术随着企业对各个信息系统之间数据共享的重视而变得越来越重要,数据同步的方法有很多,本文主要介绍基于ETL技术和基于全表扫描及哈希对比两种数据同步方法。基于ETL技术的数据同步是基于中间逻辑表完成数据转换,再通过主键和时间戳的对比而完成数据同步过程。本文以Kettle工具为例进行分析;基于全表扫描及哈希对比的数据同步是基于视图完成数据转换,再通过hash算法扫描对比而完成数据同步过程。  相似文献