毽球倒勾技术与训练     

毛亚杰 《武汉体育学院学报》2004,38(1):136-138,148

介绍了毽球倒勾技术的训练原则、训练步骤、训练方法、有拦网的训练和倒勾技术训练应注意的事项。  相似文献   

从世界杯看头球技术的重要性   总被引：4，自引：1，他引：3  

安伟震  何旭初  张中豹  张玉玲 《武汉体育学院学报》2004,38(2):98-99

统计分析第17届世界杯头球进球情况。结果显示，头球技术是一支优秀足球队比赛中成败的关键技术，应给予足够的重视。  相似文献   

基于最值中滤波的彩色图像噪声滤波器     

李葆青  文山 《六盘水师范高等专科学校学报》2003,15(4):19-21

构建了一种新的消除彩色图象中脉冲噪声的滤波法。该滤波首先根据极值点(最大或最小)的判别标准将全部像素分为两类(信号S与噪声N),再根据空间相关性将噪声点用该点邻域的中值取代,然后进行简单的局部纹理分析而自动选择使用标量中值滤波或者使用矢量中值滤波。实验表明,文中提出的方法计算量少,性能优良,图象信噪比高。  相似文献   

Lagrange中值定理在贵州专升本数学证明题上的应用     

彭良刚 《科教导刊》2019,(11):33-34

近年来贵州省普通高校选拔优秀专科生进入本科院校考试真题等式和不等式证明题已成为考试题中的重点和难点,学生在解决此类题目时往往会感觉无从下手,难以找到问题的切入点。本文着眼于构造辅助函数,利用Lagrange中值定理对等式及不等式证明题进行证明。结果表明:通过构造辅助函数后,再利用Lagrange中值定理解决此类问题更容易找到问题的切入点并且使问题简单化具体化;此外,学生熟练掌握此技巧后,会增强其自信心,解决该类证明题时更加得心应手。  相似文献   

A topography of free kicks in soccer     

Daniel Link  Otto Kolbinger  Hendrik Weber  Michael Stöckl 《Journal of sports sciences》2016,34(24):2312-2320

ABSTRACT

This study investigates the spatial relationship of performance variables for soccer free kicks. In order to suggest ways in which players might optimise their performance, we collected data from free kicks (<35 m to goal line) of two German Bundesliga seasons (2013/14, 2014/15) (n = 1624). In the analysis, we applied the ISO-map approach using colour gradients to visualise the mean values of a variable on a 2D-map of the pitch. Additionally, variograms were used to describe the degree of spatial dependence of the free kick variables. Results show that DENSITY, TYPE OF PLAY, PLAYERS IN WALL, DISTANCE TO WALL and RULE VIOLATION were strongly spatially dependent. Centrality and proximity to the goal increased the variables PLAYERS IN WALL, RULE VIOLATIONS and INTERRUPTION TIME, and the ratio of goals scored increased from 5.9% (central far) to 10.9% (central near). In 70.9% of the shots, players preferred a switched laterality, which did not result in a higher success rate. Furthermore, there was no statistical advantage for the defensive team when DISTANCE TO WALL was below 9.15 m or when there was a RULE VIOLATION. Crosses had a success rate (i.e., first controlled ball contact after the cross) of 20.8%. Played with natural laterality, they were 5% more successful than with switched laterality. Crosses from the right side outside the penalty box were 10% more successful than from the left side. Therefore, it might be worthwhile practising the defence of balls coming from this side.  相似文献   

基于Hook函数的键盘鼠标动作记录与回放的研究与实现     

张璇  王鸿飞 《漯河职业技术学院学报》2005,4(1):35-38

教学软件或系统监视软件可rT,自动记录回放用户的输入文字或点击按钮等操作。论述了HOOK函数的关键技术．提出了用HOOK函数解决键盘鼠标动作记录与回放的方案，并给予了实现。  相似文献   

第16届世界杯足球赛亚洲球队与世界杯前八名球队运用定位球进攻战术之比较     

毛卫国 《广州体育学院学报》2001,21(3):55-58

为了提高我国高层次足球队定位球进攻战术水平，通过对第16届世界杯决赛阶段亚洲球队和世界杯前八名球队定位球进攻情况的调查统计、对比研究，初步分析了世界强队的优势及亚洲球队普遍存在的问题。研究表明，亚洲球队有意识、有目的地制造和利用定位球战机的能力差；上半时运用次数少，且质量低，效果差；在运用不同的定位球进攻方式中，角球进攻破门得分的水平与世界强队的差距较大。  相似文献   

Method of Teaching Swimming in Deep Pool     

FU Jinxue  SUN Yiqian  GAO Jinying  LI Po  LIU Ying jinan 《北京体育大学学报》1995,(Z2)

To meet the need of teaching swimming in deep pool, the study designed a set of teaching method, by which beginners cou1d learn breast stroke and swim up to 5O meters in deep water. The newly designed method put emphasis on intensified technical drill on land and aJso included simplified procedure of getting familar with the characteristics of water, improved sequence of coordination, use of floats as aids, and adoptation of collective teaching form. The method has been proved to be safe, more effective with less teaching hours and uniform progreess, and consistent to the mental and physiological characteristics of beginners.  相似文献   

Unsteady flow phenomena in human undulatory swimming: a numerical approach     

Steffen Pacholak  Stefan Hochstein  Alexander Rudert  Christoph Brücker 《Sports biomechanics / International Society of Biomechanics in Sports》2014,13(2):176-194

The undulatory underwater sequence is one of the most important phases in competitive swimming. An understanding of the recurrent vortex dynamics around the human body and their generation could therefore be used to improve swimming techniques. In order to produce a dynamic model, we applied human joint kinematics to three-dimensional (3D) body scans of a female swimmer. The flow around this dynamic model was then calculated using computational fluid dynamics with the aid of moving 3D meshes. Evaluation of the numerical results delivered by the various motion cycles identified characteristic vortex structures for each of the cycles, which exhibited increasing intensity and drag influence. At maximum thrust, drag forces appear to be 12 times higher than those of a passive gliding swimmer. As far as we know, this is the first disclosure of vortex rings merging into vortex tubes in the wake after vortex recapturing. All unsteady structures were visualized using a modified Q-criterion also incorporated into our methods. At the very least, our approach is likely to be suited to further studies examining swimmers engaging in undulatory swimming during training or competition.  相似文献   

Outlier detection by means of robust regression estimators for use in engineering science   总被引：1，自引：0，他引：1  

Serif Hekimoglu  R. Cuneyt Erenoglu  Jan Kalina 《浙江大学学报(A卷英文版)》2009,10(6):909-921

This study compares the ability of different robust regression estimators to detect and classify outliers. Well-known estimators with high breakdown points were compared using simulated data. Mean success rates （MSR） were computed and used as comparison criteria. The results showed that the least median of squares （LMS） and least trimmed squares （LTS） were the most successful methods for data that included leverage points, masking and swamping effects or critical and concentrated outliers. We recommend using LMS and LTS as diagnostic tools to classify outliers, because they remain robust even when applied to models that are heavily contaminated or that have a complicated structure of outliers.  相似文献