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   

Social network data to alleviate cold-start in recommender system: A systematic review     

Lesly Alejandra Gonzalez Camacho  Solange Nice Alves-Souza 《Information processing & management》2018,54(4):529-544

Recommender Systems are currently highly relevant for helping users deal with the information overload they suffer from the large volume of data on the web, and automatically suggest the most appropriate items that meet users needs. However, in cases in which a user is new to Recommender System, the system cannot recommend items that are relevant to her/him because of lack of previous information about the user and/or the user-item rating history that helps to determine the users preferences. This problem is known as cold-start, which remains open because it does not have a final solution. Social networks have been employed as a good source of information to determine users preferences to mitigate the cold-start problem. This paper presents the results of a Systematic Literature Review on Collaborative Filtering-based Recommender System that uses social network data to mitigate the cold-start problem. This Systematic Literature Review compiled the papers published between 2011–2017, to select the most recent studies in the area. Each selected paper was evaluated and classified according to the depth which social networks used to mitigate the cold-start problem. The final results show that there are several publications that use the information of the social networks within the Recommender System; however, few research papers currently use this data to mitigate the cold-start problem.  相似文献   

Head start and the intensification of teaching in early childhood education     

《Teaching and Teacher Education》2014

Head Start is the largest early childhood education program in the US. Echoing patterns emerging in ECE world-wide, Head Start has dramatically changed. Greater emphasis is now placed on kindergarten readiness, child and teacher assessment, professionalization, and increased competition for program funding. Drawing on a mixed methods research design, a case study was conducted that explores the nature and effects of these changes on teachers and the work of teaching within Head Start. Strong evidence of work intensification was found, a topic little explored within the wider ECE literature. In the light of this finding the authors question the model of professionalism that now dominates ECE reform.  相似文献   

大学毕业生到农村创业面临的问题及对策     

赵经武 《沈阳教育学院学报》2011,(5):22-24

论述了大学生农村创业的意义,分析了创业过程中遇到的问题,并依据这些问题常识性地提出了解决的策略。  相似文献   

大学生淘宝创业研究   总被引：1，自引：0，他引：1  

郭俊朝  安宁  尹雨晴  张丽存 《邢台职业技术学院学报》2011,28(6):62-64

近年来,淘宝网的迅猛发展为青年人创业提供了很好的平台。当前,在大学生就业十分困难的严峻形势下,指导大学生利用淘宝网创业,探索适合在校大学生淘宝创业的模式,具有十分重要的现实意义。  相似文献   

我国男子单人皮艇200 m选手起航阶段平衡技术比较研究     

许耶力  潘慧炬 《天津体育学院学报》2011,26(1):27-29

运用SIMI Motion 7.50运动分析系统,对2010年皮划艇(静水)春季冠军赛(上海)决赛阶段的男子单人皮艇200m(MK1-200m)决赛A、B、c组第4道3位选手的平衡情况进行分析,讨论优秀男子皮艇选手起航阶段的平衡特征.结果表明:选手出发前左右肩关节的晃动明显,幅度大,稳定性差,左右髋关节晃动程度低,稳定性好.晃动主要集中在上半身,选手在出发前维持身体平衡主要是靠肩关节、手臂的配合来完成的.选手在出发前的平衡情况直接影响到选手的最终比赛成绩,良好的出发前平衡状态有利于参赛选手的比赛发挥,建议针对肩关节以及整个上半身做平衡的专门训练,提高选手协凋配合能力,改善起航阶段平衡状况,提高比赛成绩,创出佳绩.  相似文献   

对当代大学生创业心理的研究与思考     

葛骁欧  延诺  吴景东 《科教文汇》2011,(32):199-200

大学生创业已经成为社会共同关注的话题。高校鼓励当代大学生创业,但大学生的创业心理对其是否选择创业有很大影响,这值得我们给予更多的思考和关注。本文通过研究,从大学生创业的现状出发,分析得出影响大学生产生创业心理的因素,从而探索出大学生创业应具有的心理品质。  相似文献   

阅读教学的魅力修炼     

胡红霞 《科教文汇》2011,(23):97-97,101

阅读既是一个人了解世界和思考世界的过程,又是一个人心灵受到熏陶的过程,对人的成长至关重要。让孩子喜欢学习、喜欢阅读、感受阅读的乐趣,是我们执著的追求,做到语文素养的提高和思想教育双丰收,也正是素质教育努力实现的目标。  相似文献   

2008年全国游泳冠军赛接力项目接跳技术分析     

杨红春  毛旭江  石锴  宋福康 《浙江体育科学》2010,32(2):97-99,116

通过对2008年全国游泳冠军赛接力项目全部参赛队的预、决赛反应时间、接跳时间的统计分析，发现参赛运动队总体接跳时间较2001年时有明显进步。各队之间反应时间没有差异，提示不同代表队之间接跳水平时间的差异源于对接跳技术的科研重视及专项训练。建议运动队训练运动员采用出发动量较大的后环绕摆臂或后倾蹲踞式接力出发技术，并进行充分的接跳配合训练。  相似文献   

Effects of false-start disqualification rules on response-times of elite-standard sprinters     

Kevin C. Brosnan  Kevin Hayes  Andrew J. Harrison 《Journal of sports sciences》2017,35(10):929-935

The 100 ms ruling for false start disqualification at athletic competitions governed by the International Association of Athletics Federations has been in force since the early 1990s. Throughout this period, there have been marked changes to the rules that govern the disqualification of athletes from sprint events incorporating starts from blocks. This study analysed all available World and European Championship response-time (RT) data from 1999 to 2014 to examine effects of rule changes on competition RT at major championships. The exponentially modified Gaussian distribution was used to model RT and make comparisons relative to athletes’ sex, ruling periods and competition rounds. Revised RT thresholds of 115 ms and 119 ms were identified for men and women, respectively, indicating that the current 100 ms rule could result in some false starts not being detected in competitive athletics. The study proposes that when using existing International Association of Athletics Federations approved systems, the false start detection threshold should be increased and that men and women athletes should have different thresholds because of substantial evidence of a sex-based difference in RT in elite-standard athletes.  相似文献