赛艇双桨叶不同浸水深度对划水性能影响向试验研究

本对赛艇复合材料的刚性“Big Blade”双桨桨叶进行了循环水槽试验研究。试验采用1：1的实际模型。在不同深度下进行研究．同时试验还考虑了桨叶的不同攻角、斜角和转角。试验表明：不同的深度对桨叶的流动力性能有较大的影响．为教练员运动员进行科学训练提供了依据，不同的运动员应根据实际情况调整桨叶桨架，保持桨叶的合适深度。     

赛艇

G861.412,G804.65 9803107赛艇浆叶不同斜角对性能的影响=The performanceeffect of different oblique angle of scull〔刊,中,A〕/郑伟涛,韩久瑞,葛新发,易名农,王季安,黄谦∥武汉体育学院学报.-1998(2).-51-54图4参1(TY)赛艇∥桨∥流体动力学∥角度∥力学分析本文对目前常用的赛艇双桨桨叶进行了循环水槽实验研究。试验采用1:1的模型,在不同斜角下进行。试验还考虑了桨叶的不同攻角、深度和转角。试验表明:不同的斜角对桨叶的流体动力学性能有较大的影响,为教练员运动员进行科学训练提供了依据。     

赛艇运动中频率、浸水深度和幅度之间的关系

研究通过对赛艇“Blig Blade”桨叶的流体动力性能的数值模拟和试验研究以及理论分析，讨论了不同的划桨频率、浸水深度和划桨幅度等运动学参数和动力学参数对桨叶流体动力性能的影响，研究结果和结论：（1）桨叶与水之间的相对运动是桨叶产生作用力的根本原因；（2）随着桨叶浸水深度的增加，桨叶产生的作用力也在增加；（3）大的划桨幅度推进效率是比较低的。建议：划船器材的调整和划船技术都应围绕提高水下的拉桨速度来进行，提高拉桨频率不能够以牺牲桨叶的浸水深度为代价，更不能以牺牲频率来服朋幅度。     

起跑器抵脚板水平旋转角度对短跑运动员起跑蹬伸力的前导性研究

目的:比较分析不同起跑器抵脚板水平旋转角度对运动员起跑蹬伸力的影响。方法:以大学高水平男子短跑运动员为实验对象,将改造的抵脚板分别安装于两台三维测力平台上。实验对象按照个人习惯对起跑器长度和倾斜度进行调节设置,设置完成后不做改变。实验只对起跑器水平旋转角度进行控制,共设定4种条件:1)两支抵脚板均外旋0°;2)两支抵脚板均外旋2.5°;3)两支抵脚板均外旋5°;4)运动员根据前3种抵脚板外旋角度的主观体验,对两支抵脚板转角分别进行个性化调整。通过测力平台对4种实验条件下运动员起跑前、后脚蹬伸力幅值和时间特征进行记录。结论:1)带有旋转角度的前抵脚板在X、Y和Z方向均增加了起跑蹬伸力峰值,尤其在X方向更为显著;虽然后抵脚板在X方向减小蹬伸力峰值,但其增加了Y和Z方向蹬伸力峰值,尤其是最佳转角在Y方向增加10%的向前推力;2)2.5°转角几乎没有改变前、后脚蹬伸力出现时相,但5°和最佳转角改变了蹬伸力峰值出现时相;3)5°转角显著性地缩短蹬离时间0.0166s,最佳转角缩短蹬离时间0.0063s;4)带有旋转角度的抵脚板有利于运动员起跑后第一步侧向蹬伸,减少蹬伸侧滑现象。建议未来起跑器改进与优化应重点考虑抵脚板水平旋转角度因素。     

中国精英女子赛艇运动员划桨技术特点分析

目的：以国家队和赛艇优势省队运动员为测试对象，总结分析我国精英女子赛艇运动员的划桨技术特点。方法：27名运动员参与本研究，利用"BioRow Tel"系统测试五种桨频（20、24、28、32、36桨/分）下的划桨技术，测试参数包括划桨节奏、桨叶轨迹、桨力特征等。结果：拉桨时间百分比随桨频的提高显著提高；入水角、出水角和划幅在中低桨频下非常稳定，但在接近比赛桨频时显著下降；抓水打滑和出水打滑均随桨频的增加而显著增加；与桨力相关的参数对桨频的变化相对不敏感。结论：我国运动员较为注重桨叶入水和拉桨前段，表现出的技术较好，而在拉桨后段特别是桨叶出水阶段暴露出的问题比较大；临近比赛桨频时的技术同中低桨频时相比存在比较明显的下降。训练中要解决好拉桨后段和桨叶出水的问题，并注重提高运动员在比赛桨频时的划桨技术。     

游泳运动员赛前最佳状态时身体成分分析

目的:旨在研究重大比赛前最佳状态时游泳运动员的身体成分,按不同性别、不同距离、不同运动等级、不同年龄段进行分类比较.方法:以浙江游泳队45名运动员为研究对象,测试时间为早上7点,空腹,采用韩国INBODY3.2型身体成分分析仪进行分析.研究结果:游泳运动员,男子体脂率应保持在9%左右,女子体脂率应保持在15%左右较为理想;短距离游泳运动员体脂率明显低于中长距离运动员;瘦体重明显高于中长距离运动员;男子游泳运动员身体成分比例较合理的出现在19～21岁这个年龄段,女子出现在16～18岁这个年龄段;游泳运动员体脂率高低与运动等级的相关性不大.     

赛艇WH1x运动员段静莉划桨技术动作特征分析

目的：总结和借鉴优秀运动员的技术特点,应用BioRow赛艇技术测试分析系统对里约奥运会奖牌获得者段静莉划桨技术动作特征进行分析,提供相应技术参数供参考。方法：通过实船测试获得段静莉各个划桨阶段的技术参数,从桨叶控制技术、划桨风格和艇速及艇加速度三方面对段静莉的划桨技术特征进行分析总结。结论：(1)段静莉的拉桨阶段的桨叶控制有待提高,特别是桨叶入水打滑角度和桨叶出水打滑角度均偏大,桨叶入水深,不利于拉桨后期做功效率;(2)段静莉回桨阶段桨叶控制技术良好,桨叶轨迹稳定性较良好,桨叶高度适中;(3)段静莉的划桨风格属于“卢森博格”的中发力模式;(4)艇速及艇加速度是评价运动员划桨技术简单直接有效的方式。     

投篮命中率与12项感知觉指标关系的初步综合研究

运用文献资料、心理实验测量和数理统计等研究方法，对61名3个级别篮球运动员的12项感知觉指标与投篮命中率的关系进行了研究。不同水平篮球运动员投篮命中率与感知觉因素相关程度不一致，高水平辽青队的投篮命中率主要与手动稳定性和深度视觉相关，中等水平院队主要与两点辨别阈和手动稳定性相关，低水平专选学生主要与手动稳定性、手指握力准确度和时空判断相关。提示：不同水平篮球运动员今后在训练时应注意加强较弱感知觉能力的培养，充分挖掘心理潜力。     

自由式滑雪空中技巧国家队一线与二线运动员隐性知识水平比较研究

以知识管理理论为基础,运用问卷调查、深度访谈等研究方法,在对自由式滑雪空中技巧运动员隐性知识内容体系维度界定基础上,对自由式滑雪空中技巧国家队一线与二线运动员进行了比较分析,提出了改进策略,希望能为保持该项目的持续领先地位提供参考依据.     

对武术散打运动员科学化选材的内容体系研究

在现代运动训练日益科学化、规范化的今天，如何对散打运动员进行科学选材已越来越成为诸多教练员及科研人员关注的焦点。文章采用文献资料法、专家咨询法等方法，首先从对武术散打运动员进行科学选材的几个不同阶段的划分入手，提出了不同阶段的选材要求；其次提出了建立武术散打运动员的“常模”，认为优秀武术散打运动员的模式特征，可以对武术散打的科学选材提供目标和方向；最后提出了对武术散打运动员进行科学选材时应借鉴和参考的指标体系以及与之相关的其他方面的几个因素。     

Rowing

The purpose of this study was to compare rowing technique on the dynamic RowPerfect ergometer with a single scull. Eight national‐level rowers performed on both the RowPerfect ergometer and in a single scull over 500 m, at rates of 24, 26, and 28 strokes/minute. Blade force and oar angle (on‐water) and handle force and stroke length (on the ergometer) were measured. Both force and stroke angle/length were normalised from 0 to 100 (where 100 was the peak value). Body positions of the subjects at both the catch and finish of each of these rowing strokes were also compared for each stroke rate. The coefficient of multiple determination (CMD) was used to measure the consistency of force curves over a sample of five sequential strokes for each rower. Cross‐correlations were performed between the left‐ and right‐ side on‐water sculling force curves and a mean of these values with the ergometer curve for each rower. Stroke angle/length, which did not vary with rate, was similar for both forms of rowing. The CMDs showed a high consistency across the normalised strokes of each subject (≈0.98). Cross‐correlation values of 0.91, 0.92, and 0.93 were recorded between the force curves from the ergometer and on‐water trials for stroke rates of 24, 26, and 28 strokes/minute, respectively. The mean trunk, thigh and lower leg angles at the catch and finish of the stroke were also similar across the stroke rates as determined by t‐tests. Results indicate that technique used on the RowPerfect ergometer was similar to that for on‐water sculling, thus validating its use in off‐water training.     

The RowPerfect ergometer: a training aid for on-water single scull rowing

The purpose of this study was to compare rowing technique on the dynamic RowPerfect ergometer with a single scull. Eight national-level rowers performed on both the RowPerfect ergometer and in a single scull over 500 m, at rates of 24, 26, and 28 strokes/minute. Blade force and oar angle (on-water) and handle force and stroke length (on the ergometer) were measured. Both force and stroke angle/length were normalised from 0 to 100 (where 100 was the peak value). Body positions of the subjects at both the catch and finish of each of these rowing strokes were also compared for each stroke rate. The coefficient of multiple determination (CMD) was used to measure the consistency of force curves over a sample of five sequential strokes for each rower. Cross-correlations were performed between the left- and right-side on-water sculling force curves and a mean of these values with the ergometer curve for each rower. Stroke angle/length, which did not vary with rate, was similar for both forms of rowing. The CMDs showed a high consistency across the normalised strokes of each subject (approximately 0.98). Cross-correlation values of 0.91, 0.92, and 0.93 were recorded between the force curves from the ergometer and on-water trials for stroke rates of 24, 26, and 28 strokes/minute, respectively. The mean trunk, thigh and lower leg angles at the catch and finish of the stroke were also similar across the stroke rates as determined by t-tests. Results indicate that technique used on the RowPerfect ergometer was similar to that for on-water sculling, thus validating its use in off-water training.     

女子赛艇运动员赛前训练激素变化及双、多人艇不同桨位训练强度的研究

研究女子赛艇运动员赛前强化训练中某些激素指标的变化规律及双、多人艇不同桨位运动员的训练强度。结果显示,大负荷训练使运动员的T、C和GH逐步发生变化,但变化的时间和方向不同。提示,T、C及GH是赛艇运动员机能评定的有效指标。双、多人艇不同桨位运动员承受训练负荷强度存在明显差异,这种差异随训练强度的增加而增大,长时间的双、多人艇训练会对领桨手的耐力及跟桨手的速度产生不良影响。     

Measurements of the horizontal and vertical speeds of tennis courts

Tennis courts are normally classified as fast or slow depending on whether the coefficient of sliding friction (COF) between the ball and the surface is respectively small or large. This classification is based on the fact that the change in horizontal ball speed is directly proportional to the COF if the ball is incident at a small angle to the horizontal. At angles of incidence greater than about 16° it is commonly assumed that the ball will roll during the bounce, in which case one can show that the ratio of the horizontal speed after the bounce to that before the bounce will be 0.645 regardless of the angle of incidence or the speed of the court. Measurements are presented showing that (a) at high angles of incidence, tennis balls grip or ‘bite’ the court but they do not roll during the bounce, (b) the bounce:speed ratio can be as low as 0.4 on some courts and (c) the normal reaction force acts through a point ahead of the centre of mass. An interesting consequence is that, if court A is faster than court B at low angles of incidence, then A is not necessarily faster than B at high angles of incidence. An exception is a clay court which remains slow at all angles of incidence. The measurements also show that the coefficient of restitution for a tennis ball can be as high as 0.9 for an oblique bounce on a slow court, meaning that the ball bounces like a superball in the vertical direction and that slow courts are fast in the vertical direction.     

Realistic evaluation of hull performance for rowing shells, canoes, and kayaks in unsteady flow

In this study, we investigated the effect of hull dynamics in shallow water on the hydrodynamic performance of rowing shells as well as canoes and kayaks. An approach was developed to generate data in a towing tank using a test rig capable of reproducing realistic speed profiles. The impact of unsteady shallow-water effects on wave-making resistance was examined via experimental measurements on a benchmark hull. The data generated were used to explore the validity of a computational approach developed to predict unsteady shallow-water wave resistance. Comparison of measured and predicted results showed that the computational approach correctly predicted complex unsteady wave-resistance phenomena at low oscillation frequency and speed, but that total resistance was substantially under-predicted at moderate oscillation frequency and speed. It was postulated that this discrepancy arose from unsteady viscous effects. This was investigated via hot-film measurements for a full-scale single scull in unsteady flow in both towing-tank and field-trial conditions. Results suggested a strong link between acceleration and turbulence and demonstrated that the measured real-world viscous-flow behaviour could be successfully reproduced in the tank. Thus a suitable tank-test approach could provide a reliable guide to hull performance characterization in unsteady flow.     

A mathematical model of the oar blade - water interaction in rowing

Our aim was to present a mathematical model of rowing and sculling that allowed for a comparison of oar blade designs. The relative movement between the oar blades and water during the drive phase of the stroke was modelled, and the lift and drag forces generated by this complex interaction were determined. The model was driven by the oar shaft angular velocity about the oarlock in the horizontal plane, and was shown to be valid against measured on-water mean steady-state shell velocity for both a heavyweight men's eight and a lightweight men's single scull. Measured lift and drag force coefficients previously presented by the authors were used as inputs to the model, whichs allowed for the influence of oar blade design on rowing performance to be determined. The commonly used Big Blade, which is curved, and it's flat equivalent were compared, and blade curvature was shown to generate a 1.14% improvement in mean boat velocity, or a 17.1-m lead over 1500 m. With races being won and lost by much smaller margins than this, blade curvature would appear to play a significant role in propulsion.     

A mathematical model of the oar blade – water interaction in rowing

Abstract

Our aim was to present a mathematical model of rowing and sculling that allowed for a comparison of oar blade designs. The relative movement between the oar blades and water during the drive phase of the stroke was modelled, and the lift and drag forces generated by this complex interaction were determined. The model was driven by the oar shaft angular velocity about the oarlock in the horizontal plane, and was shown to be valid against measured on-water mean steady-state shell velocity for both a heavyweight men's eight and a lightweight men's single scull. Measured lift and drag force coefficients previously presented by the authors were used as inputs to the model, whichs allowed for the influence of oar blade design on rowing performance to be determined. The commonly used Big Blade, which is curved, and it's flat equivalent were compared, and blade curvature was shown to generate a 1.14% improvement in mean boat velocity, or a 17.1-m lead over 1500 m. With races being won and lost by much smaller margins than this, blade curvature would appear to play a significant role in propulsion.     

A study of the forces exerted by an oarsman and the effect on boat speed

A model of the motion of a single‐scull rowing hull has been developed and verified against rowing performance data. The model was then used to explore the effect of changes in the cyclic rowing force on the boat speed. The calculations have shown that the shape of the rowing force curve and the proportion of recovery time in the total stroke can have an important effect on the boat speed. It has also been shown that a study of the fluid mechanics of the oar blade would be advantageous in determining whether a reduction in the power wasted can be obtained by changing the ratio of rowing force to normal force.     

论赛艇动力学及提高赛艇技术的途径

用新型智能仪表SF2船速桨频测量仪采集数据,依据动量原理,建立赛艇动量方程及动力学方程。指出,桨手在滑座上移动时,人体质心动量变化产生的力在回桨和拉桨期都会各自交替产生动力和阻力,一般拉桨前期产生阻力,后期产生动力,回桨时相反。强调回桨质量,注意延长各段的动力作用时间,缩短阻力时间,加强低频训练和“意”练,让船速和桨频同步提高。     

湖北省优秀女子公开级赛艇单人双桨技术分析

利用奥地利WEBA Spon公司的Rower Expert Light赛艇实船测试系统对4名女子公开级赛艇运动员进行单人双桨实船划桨测试.分析发现:随着桨频的增加,拉桨与推桨更加迅速,但推桨速度增加得更快.桨频的增加会使得拉桨速度加快但并没有伴随着拉力的显著增加,而拉力的大小对于艇速并不起决定性作用.在相同桨频下,较小...