20公里竞走运动员犯规与速度节奏变化的关系分析

通过对第12届全运会20公里竞走比赛的成绩、技术数据以及裁判资料的收集整理,对20公里竞走比赛过程中运动员技术犯规的情况进行统计,结合运动速度节奏变化分析运动员速度节奏变异与技术犯规趋势关系,得出速度节奏变化与犯规存在相关性,为教练员安排运动员比赛的技战术提供参考。     

背向滑步推铅球的衔接技术

衔接技术是铅球投掷技术的重要环节，是沟通滑步技术与最后用力技术的关键。恰当地把握这一项技术环节是完整推铅球技术的核心。衔接技术又叫过渡步技术，近几年来，对优秀运动员推铅球的衔接技术有适当的分析。本文在前人实验的基础上，对衔接技术进行综合分析，目的在于正确阐明衔接技术的要领，衔接技术与滑步技术、预行速度、重心移动轨迹等之间存在的关系，从而使整体技术更加符合运动技术原理，利于提高运动成绩。     

企业信息化建设速度、成本与质量统筹研究

在企业信息化建设过程中,速度、成本与质量既相互制约又相互促进,形成了一个三角关系,如果想建设速度快且质量好,那成本不会太低;如果想建设速度快且成本低,那质量就会大打折扣;如果想建设质量好且成本低,那速度上会相对缓慢些。主要围绕企业信息化建设速度、成本与质量三者相互间的关系进行阐述,并就如何平衡三者间的关系进行了探讨。     

智能监控中的运动检测算法研究

介绍了室内智能监控系统中运动检测算法的具体实现。利用帧间差分法提取运动目标,通过对差分能量和运动速度的分析判断出运动目标的大致动作。     

The physiological cost of velocity coupling during tennis groundstrokes

Abstract

Velocity coupling denotes a perceptual motor behaviour known to occur during coincidence timing tasks. Individuals have been shown to increase their effector limb speed with increases in stimulus speed during interceptive tasks. However, little is known about the physiological effects of velocity coupling. The aim of this study was to determine the physiological cost of velocity coupling during tennis groundstrokes. Eight male and eight female competitive tennis players volunteered to perform three 4-min bouts of continuous groundstrokes against balls projected from a tennis ball machine at speeds of 18, 22, and 27 m · s^?1 (65, 79, and 97 km · h^?1) and a frequency of 14 balls per minute, the order of which was counterbalanced. Breath-by-breath pulmonary gas exchange, heart rate, locomotion time, and limb acceleration were measured throughout each of the 4-min bouts. Capillary blood samples (for blood lactate analysis), rating of perceived exertion, and difficulty rating were taken at the end of each bout. Increasing ball speed did not influence the locomotion time between groundstrokes but did result in a bilateral increase in both the mean upper- and lower-limb acceleration (all P < 0.05). Velocity coupling behaviour increased oxygen uptake, blood lactate concentration, heart rate, rating of perceived exertion, and perceived task difficulty (all P < 0.05). It would appear, therefore, that velocity coupling influenced tennis groundstroke behaviour and indirectly modified the concurrent cardiopulmonary and metabolic responses.     

A comparison of the intra-cyclic velocity variation in breaststroke swimmers with flat and undulating styles

The aim of this study was to establish differences in intra-cyclic horizontal velocity variation of the body's centre of mass in breaststroke swimmers with flat and undulating styles. Vertical eel-like body waving and trunk rotations were measured to distinguish styles. To reconstruct trunk extension and kyphosis in the poorly visible zone close to the water surface, a semi-automated video-analysis system was developed. From 45 internationallevel swimmers examined, two groups of women and two groups of men were identified, those using the most undulating and those using the flattest styles. Among the men with the flattest style, the maximum and minimum horizontal velocity of the body's centre of mass differed by 76% from the mean swimming velocity; among the women with the most undulating style, the figure was 53%. In the most undulating style, less horizontal velocity variation of the body's centre of mass could be explained by movements of the body parts above the water surface, creating a transfer of momentum: a quick backward upper trunk rotation generates resistance and a quick forward shoulder girdle and upper arm movement, followed by a quick forward upper trunk and head rotation, generates propulsion. In addition, during an upward leg kick, some swimmers generated propulsion similar to that seen in eels.     

我国优秀游泳运动员途中游速度、划频、划幅变化的研究

竞技游泳途中游的速度取决于划频和划幅两个因素。通过实验观测和比较,分析了我国最高水平游泳运动员成绩及途中游速度、划频、划幅的现状与变化情况,并结合身材、动作效率等因素,对如何调控划频、划幅以促进我国游泳运动员水平的进一步提高提出了参考意见。     

试析影响跳远成绩的因素

本采用献法，对影响跳远成绩的因素进行分析，发现在诸多因素中腾起初速度与腾起角是影响跳远的主要因素，提出了提高助跑水平速度是提高跳远成绩的关键。     

我国货币流通速度变动因素的计量分析

改革开放以来我国货币流通速度出现了不断下降的趋势。文章主要运用计量经济学的方法，验证影响我国货币流通速度变动不断下降的主要原因是货币化程度和利率，同时随着金融发达程度的提高会加速货币流速。     

高速漏磁检测中速度效应的研究

介绍了漏磁检测中速度效应的基本原理,研究了高速检测下漏磁信号的变化规律,并对高速检测下的磁路设计和电路设计提出了改进.