射箭全球史试探:丝绸之路考古所见两种角弓考释

综合运用文献研究与考古文物资料分析相结合的方法,辅以射箭运动的基本训练学规律与传统弓箭制作之田野实证,对新疆地区两种出土角弓进行考释。得出如下结论:弓弰翻卷的连弧蛇形角弓是斯基泰人基于骑马游牧的传统、野兽崇拜的心理、便利的北山羊角取材,在继承了亚述三角弓“翻卷的弓弰”设计理念后的革故鼎新;弓渊宽阔,弓弣微凹的插接型长弰角弓起源于公元前2世纪的帕提亚帝国。随着丝绸之路的贯通,交流频度与交流速度的激增使该器形迅速为整个欧亚大陆的民族所复刻。其中,中华文明赋予了其最重要的文化内涵,使原本用于战争的武器有了超越物态的“礼”的象征意义。     

垒球投手间隙训练法浅谈

在垒球教学训练中,对投手采取间隙训练法进行训练,能有效地适应垒球比赛的特点,适应实战的需要,对投手投球训练效果将产生更积极的作用。     

中国优秀女子垒球投手快速投球投掷动作的运动学分析

对国家队女子垒球6名优秀的投手进行三维定点拍摄和录像解析,实验结果表明国家队投手对投球动作整体掌握较熟悉,动作连贯性比较一致.在整个投球过程中的各投手投掷臂肩、肘、腕关节点的加速--制动都有一定的顺序性,且各关节点速度变化的规律基本相同;其中各投手完成投球动作的伸踏时间、伸踏距离、重心下降幅度、球出手速度、球出手高度等运动学指标已达国际一流水平.     

消费者剩余与生产者剩余的博弈及其对体育产业综合效益的影响

从博弈论的角度,阐释了体育消费者剩余的重要意义和影响因素。指出体育产业作为独立的生产者和社会的合作者,在谋求产业利润最大化的同时必须重视对社会的贡献,即尊重和关怀消费者,合理让渡生产者剩余给消费者剩余,达到生产者剩余与消费者剩余的共生,实现体育产业社会效益与经济效益的最大化。     

太极柔力球的现状与发展对策

太极柔力球运动是一改传统硬性击球方式,以弧形引化过程触及球体并顺势将球抛出为主要技术特征的,有鲜明民族特色的新兴体育运动项目.就太极柔力球的发源、发展及运动特点进行了较深入研究,并对发展过程中面临的困难提出了相应对策,为今后更好发展该项目提供参考价值.     

排球跳传技术的研究

跳传是排球运动中一项重要技术,在排球比赛中运用跳传技术组织进攻有许多优点,熟练地掌握跳传技术对比赛获胜具有重要作用,文中对跳传的移动取位、起跳和空中动作的要求、传球的时机、击球点和传球手型、击球部位和用力方向、落地的技术等方面均从理论与实践结合上作了科学的剖析。     

浅谈儿童早期训练时球拍的结构

教学与训练的实践证明,对早期少儿乒乓球训练的球拍,需要进行科学改进,它既有利于技术水平的掌握与提高,又有利于少儿的健康成长。     

Describing the plastic deformation of aluminium softball bats

Hollow aluminium bats were introduced over 30 years ago to provide improved durability over wooden bats. Since their introduction, however, interest in hollow bats has focused almost exclusively around their hitting performance. The aim of this study was to take advantage of the progress that has been made in predicting bat performance using finite elements and apply it to describe bat durability. Accordingly, the plastic deformation from a ball impact of a single-wall aluminum bat was numerically modelled. The bat deformation from the finite-element analysis was then compared with experiment using a high-speed bat test machine. The ball was modelled as an isotropic, homogeneous, viscoelastic sphere. The viscoelastic parameters of the ball model were found from instrumented, high-speed, rigid-wall ball impacts. The rigid-wall ball impacts were modelled numerically and showed good agreement with the experimentally obtained response. The strain response of the combined bat-ball model was verified with a strain-gauged bat at intermediate ball impact speeds in the elastic range. The strain response of the bat-ball model exhibited positive correlation with the experimental measurements. High-speed bat-ball impacts were performed experimentally and simulated numerically at increasing impact speeds which induced correspondingly increased dent sizes in the bat. The plastic deformation from the numerical model found good agreement with experiment provided the aluminium work hardening and strain rate effects were appropriately described. The inclusion of strain rate effects was shown to have a significant effect on the bat deformations produced in the finite-element simulations. They also helped explain the existence of high bat stresses found in many performance models.     

Braided composite materials for the production of lightweight, high rigidity golf shafts

Braiding is not currently used in the production of golf shafts. The objective of this work was to develop, through a modelling process consisting of altering lamina sequence, a golf shaft, using braided laminas, which would have mass, stiffness and torque comparable to commercially available composite and steel shafts. A 2D conical braided composite model was previously developed and validated to predict elastic constants of braided closed meshed structures. Energy methods were used to calculate the stiffness and torque of shafts using prescribed industry approaches. Shaft mass was calculated based on geometry and density of constitutent materials. Modelled shafts had both braided and unidirectional layers and compared favourably with or were better than commercially available composite and steel shafts in terms of deflection force and twist angle; they had the same weight as composite shafts but were much lighter than steel shafts. If these findings are verified, braided composites would be a viable and effective approach to the design of future golf shafts.     

难美项群空中身体翻转动作类型与构架研究

摘要：鉴于当前世界竞技体育项目的高速发展,为了更好的适应新形势变化,针对表现难美性项群中自由体操、单跳、蹦床、跳水和空中技巧五个项目中,身体动作的主因子“空中身体翻转动作”进行分析研究,目的是通过该研究,能够对项目间的相互借鉴、以及项目技术的相互支撑起到一定的帮助作用,并对项目的发展具有一定的实际意义。文章通过文献资料法、访谈法、录像分析法等科学研究方法进行系统分析,得到以下结论：1）空中身体翻转动作是运动员身体在空中围绕运动轴完成单向或多向翻腾和转动的技术动作,是五个表现难美性项目的核心技术。2）依时间的递进进行观察和描述,一个完整的身体翻转动作包含起动加速、起跳、空中翻转、落停4个相互连接的技术环节。3）自由体操和单跳的空中身体翻转动作常以多式样的空中身体翻腾转体难度动作直接连接另一个空中身体翻转难度动作。4）空中身体翻转技术动作的递进式发展历程可分为五个发展阶段：单一翻腾阶段;单一的翻腾或旋转阶段;复合翻转阶段;多翻多转及“叠加”翻转阶段和自由体操与单跳进入突出平面挂串连接阶段。5）发展表现难美性项群空中身体翻转动作的对策设计为：及时研究、积极适应国际评分规则的变化,科学把握空中身体翻转动作的有序性发展规律, 主动发掘空中身体翻转技术动作的创新途径。