Coordination pattern of baseball pitching among young pitchers of various ages and velocity levels

This study compared the whole-body movement coordination of pitching among 72 baseball players of various ages and velocity levels. Participants were classified as senior, junior, and little according to their age, with each group comprising 24 players. The velocity levels of the high-velocity (the top eight) and low-velocity (the lowest eight) groups were classified according to their pitching velocity. During pitching, the coordinates of 15 markers attached to the major joints of the whole-body movement system were collected for analysis. Sixteen kinematic parameters were calculated to compare the groups and velocity levels. Principal component analysis (PCA) was conducted to quantify the coordination pattern of pitching movement. The results were as follows: (1) five position and two velocity parameters significantly differed among the age groups, and two position and one velocity parameters significantly differed between the high- and low-velocity groups. (2) The coordination patterns of pitching movement could be described using three components, of which the eigenvalues and contents varied according to age and velocity level. In conclusion, the senior and junior players showed greater elbow angular velocity, whereas the little players exhibited a wider shoulder angle only at the beginning of pitching. The players with high velocity exhibited higher trunk and shoulder rotation velocity. The variations among groups found using PCA and kinematics parameter analyses were consistent.     

Position-specific performance indicators that discriminate between successful and unsuccessful teams in elite women’s indoor field hockey: implications for coaching

The aim of this investigation was to establish median performance profiles for the six playing positions in elite women’s indoor hockey and then identify whether these position-specific profiles could discriminate between qualifying (top four), mid-table and relegated teams in the 2011–2012 England Hockey premier league. Successful passing in relegated teams was significantly lower (P < 0.008) than in mid-table and qualifying teams in four of the five outfield positions. Furthermore, the right backs of qualifying teams demonstrated significantly fewer (P < 0.008) unsuccessful passes (x? = 15.5 ± CLs 15.0 and 10.0, respectively) and interceptions (x? = 4.0 ± CLs 4.0 and 3.0, respectively) than relegated teams (x? = 19.5 ± CLs 21.0 and 17.0; x? = 7.5 ± CLs 8.0 and 6.0, respectively). Finally, the right forwards of relegated teams demonstrated significantly fewer (P < 0.008) successful interceptions (x? = 4.0 ± CLs 5.0 and 4.0, respectively) than qualifying teams (x? = 5.0 ± CLs 6.0 and 3.0, respectively) and significantly more (P < 0.008) unsuccessful interceptions (x? = 5.5 ± CLs 6.0 and 4.0, respectively) than mid-table teams (x? = 3.0 ± CLs 3.0 and 2.0, respectively). Based on these findings, coaches should adapt tactical strategies and personnel deployment accordingly to enhance the likelihood of preparing a qualifying team. Research should build from these data to examine dribbling, pressing and patterns of play when outletting.     

苍溪县民俗文化活动调查分析

研究目的:更好地推动苍溪县民俗文化的发展。研究方法:文献法、访谈法、观察法等。研究结果和结论:苍溪县民俗文化活动有游百病、中秋送瓜、行香琐记、山乡栽秧酒等民俗活动,民俗活动对当地的经济发展、文化生活、社会环境都产生了积极影响。根据苍溪县民俗文化调查研究,提出了加强民俗文化底蕴的挖掘、整理、保存和研究提炼,提高民众对民俗活动的认识不断加强,进行良性的变异的建议,旨在促进苍溪县民俗文化的健康快速发展。     

中外女排比赛接拦回球效果及失误原因的比较分析

中外女排比赛中接拦回球数量仍然较多,占扣球总数的14%左右,比赛中80%左右的拦回球落在3m线前区域。中国女排接拦回球的效果好于日本女排、塞尔维亚女排和多米尼加女排,但与巴西女排、美国女排相比差距较大,同俄罗斯女排、意大利女排接拦回球的效果相差不大。接拦回球失误的主要原因有接拦回球队员反应跟不上造成无防守动作形成失误,其次是接拦回球队员防守意识不强未及时进入防守位置形成失误。中国女排应加强接拦回球跟进保护意识培养,努力提高各种倒地和单手垫球技术,从而提高接拦回球能力。     

第17届排球世锦赛中外女排进攻效果对比研究

运用录像观察、数理统计和对比分析等方法,对中外女排在第17届世锦赛中扣球技战术运用情况进行研究。结果表明：中国女排是以两边拉开进攻为主并结合高度与速度等快变战术为一体的技战术打法;进攻战术的总体运用效果十分理想,与其他各国相比扣死率较高且失误率低;后排攻在比赛中展现出了强大的实力,但在强攻和快攻方面与巴西、美国等欧美强队相比还存在一定差距。建议中国女排应进一步加强对强攻能力的训练,尤其要努力丰富年轻队员的大赛阅历以保证其技术发挥的稳定性;在面对欧美强队时应努力提高一传到位率,并加强进攻队员之间的掩护配合,使各种快变战术能够在比赛中得到有效发挥,并尽量避免自身进攻方式及手段的单一化。     

Structural dynamic responses analysis applying differential quadrature method

INTRODUCTION The differential quadrature method (DQM) was proposed by Bellman and Casti as an analogous ex- tension of the quadrature method for integrals (Bellman and Casti, 1971; Bellman et al., 1972). It can be essentially expressed as the values of the de- rivatives at each grid point as weighted linear sums approximately of the function values at all grid points within the domain under consideration. As a distinct numerical solution technique to obtain the initial and/or boundary …     

具有非期望输出决策单元的有效性评价

针对具有非期望输出决策单元DMU的相对有效性 ,提出对其进行评价的非径向FDEA模型 ,并给出模型的相对有效性理论证明 .结合实际算例 ,指出FDEA模型在实际生产过程中对于节约生产资源 ,提高期望输出 ,降低非期望输出 ,特别是减少环境污染有重要应用价值 .     

我国图书出版的经济效应--基于面板向量自回归的脉冲分析

运用面板向量自回归模型分析后发现：东部地区图书出版对经济增长带来了“先增强后减弱”的正向冲击效应,中部地区的冲击效应既不明显也不稳定,西部地区则呈现负向冲击效应。同时,东部地区出版产业的延伸和知识的外溢使得全国的图书出版带来经济的有效增长。但是,这一效应主要是通过“产业渠道”而非“传播渠道”传导的,这就使得图书出版数量上的扩张只是带动了出版产业的发展,而未能带来出版知识快速且有效的转化。     

矿井轴流式主要通风机经济运行探讨

轴流式通风机是煤矿常用的一种通风设备，用于矿井通风的轴流式风机，不仅功率大而且长时运转，因此，它是煤矿耗电量较大的机械设备之一。针对轴流式风机能量损失的一些原因作以分析，并提出使之可达到经济运行的若干技术措施。     

大学生就业影响因素中基于粗糙集的智能数据分析方法

大学生就业形势越来越严峻,影响就业的因素众多,各因素对就业情况的影响并不相同,且相互之间存在关联性。基于粗糙集理论,提出大学生就业因素重要度的定量度量方法,建立基于粗糙集的智能数据分析模型,实验结果表明了新型方法的有效性,能够为大学生的在校学习和就业规划提供了重要指导,并为高校培养和企业招聘优秀大学生提供了决策支持。