浅谈箭的空气弹道特点及其精度影响

在射箭运动项目中,如何正确地认识和掌握箭的飞行规律,追求高精度射击,是每一个射箭运动员长期辛勤劳动的最终体现。如果不能正确认识箭本身的构造特点及在全弹道里空气动力诸因素之影响,对运动员的训练,会带来一定盲目性。本篇以讨论箭在空气弹道里的飞行特点和影响射击精度的诸因素为主题,对如何建立必要的稳定飞行条件,减小散布,     

燃烧型防暴弹气溶胶颗粒舱室内扩散特性仿真

为了研究各因素对气溶胶颗粒物室内扩散特性的影响,本文以燃烧型防暴弹气溶胶颗粒物为研究对象,建立了一个相对密封的室内环境模型,基于FLUENT平台,运用两相流运动模拟中的DPM模型对防暴弹在室内投放后,主要针对混合通风条件下室内弹体施放后颗粒扩散分布,进行了数值模拟,研究观察室内的颗粒浓度,并着重研究人体呼吸高度(1.1m)处的颗粒浓度。     

殷商弹射探析

以文献、甲骨文和出土弹丸实物为依据,探讨殷商时期弹丸的类型及弹射的种类和性质,通过分析弹射活动情况,反映弹射武技在殷商时期十分盛行.     

计算流体力学在F1赛车运动中的应用

应用计算流体力学方法优化F1赛车外形设计以改善其空气动力学特性。结果表明,应用计算流体力学方法可实现在很短的时间内完成多种设计方案的模拟计算,得到赛车外形与气动阻力系数等空气动力学特性的定量关系,还可以进行F1赛车的操纵稳定性,空气噪声,排、进气道等研究。     

破骑身卡喉

当你受到歹徒袭击,身处险境时,迅速果断地运用防暴术进行自卫是你唯一的选择。只要时机得当,方法正确,你定能成功。     

特种兵教你格斗

本文中介绍的格斗术，一部分来源于军警格斗标准教材，大部分为笔者自创，在教学中实践效果极佳，因其招术十分狠辣，习者在防暴自卫时须慎用。     

用于羽毛球制造的仿真羽毛材料制备与性能研究

对仿真羽毛毛片的注塑材料进行实验研究,采用纳米技术,应用先进的设计和制造工艺,研制出比重轻、不变形、弹性好、复原性好、低碳环保,形状结构接近于天然羽毛的仿真羽毛毛片;根据空气动力学原理和人体运动规律,制造出适合城乡居民开展的室内、外运动健身的仿真羽毛球产品。     

高一女生防暴自救课教学设计

为了提高学生的综合素质，培养高中女生自我防护意识和能力，本学期我校开设了“高中女生防暴自救”课程，并纳入《体育与健康》选修课程教学，特制定教学设计如下。     

武当神像“回家”记

2007年6月21日,长龙似的押运防暴车队徐徐停靠在气势恢弘的湖北省十堰市博物馆门前,3名核枪实弹的押运员迅速从车上跳下。原来,车上押运的乃是6尊流散于陕西安康长达69年之久的     

军警擒拿 制敌技法

一、击腹铐臂 军警在防暴制敌时,左手速抓敌右臂,右手握铐用力猛击敌小腹(图1)。左手随即扯敌右手,握铐砸锁敌右腕(图2),右脚前跨步,左手从敌背后抓敌左臂,铐锁敌左腕。     

Carbohydrate ingestion improves endurance performance during a 1h simulated cycling time trial

This study examined the effect of carbohydrate ingestion on metabolic and performance-related responses during and after a simulated 1h cycling time trial. Eight trained male cyclists (VO 2 peak = 66.5ml kg -1 min -1 ) rode their own bicycles mounted on a windload simulator to imitate real riding conditions. At a self-selected maximal pace, the cyclists performed two 1h rides (separated by 7 days) and were fed either an 8% carbohydrate or placebo solution. The beverages were administered 25 min before (4.5ml kg -1 ) and at the end (4.5ml kg -1 ) of the ride. With carbohydrate feeding, plasma glucose tended (P = 0.21) to rise before the time trial. Compared with rest, the plasma glucose concentration decreased significantly (P < 0.05) at the end of both rides, with no statistically significant difference being observed between treatments. Thereafter, plasma glucose increased significantly (P < 0.05) at 15 and 30 min into recovery, and was significantly higher at 30 min during the carbohydrate trial compared with the placebo trial. No significant changes in plasma free fatty acids were observed during the ride. However, a significant increase (P < 0.05) in free fatty acids was found at 15 and 30 min into recovery, with no difference between trials. Mean power output was significantly (P < 0.05) greater during the carbohydrate compared with the placebo trial (mean - S.E.: 277-3 and 269-3W, respectively). The greater distance covered in the carbohydrate compared with the placebo trial (41.5-1.06 and 41.0–1.06km, respectively; P < 0.05) was equivalent to a 44s improvement. We conclude that pre-exercise carbohydrate ingestion significantly increases endurance performance in trained cyclists during a 1h simulated time trial. Although the mechanism for this enhancement in performance with carbohydrate ingestion cannot be surmised from the present results, it could be related to a higher rate of carbohydrate oxidation, or to favourable effects of carbohydrate ingestion on the central component of fatigue.     

Science and medicine of rowing: A review

The biology and medicine of rowing are briefly reviewed. Effort in a 2000 -m race is about 70% aerobic. Because the boat (and in some instances a cox) must be propelled, successful competitors are very tall, with a large lean mass and aerobic power. Large hearts may lead to erroneous diagnoses of a cardiomyopathy. Large respiratory minute volumes must be developed by chest muscles that are also involved in rowing. The vital capacity is typically large, and breathing becomes entrained. Expiration cannot be slowed relative to inspiration (as normally occurs at high rates of ventilation) and the limiting flow velocity may be reached, with the potential for airway collapse. Performance is strongly related to the power output at the ‘anaerobic threshold’, and lactate measures provide a guide to an appropriate intensity of endurance training. Peak blood lactate levels are higher in males (commonly 11–19 mmol·l -1 and occasionally as high as 25 mmol·l -1) than in females (9–11 mmol·l -1), probably because males have a greater muscle mass in relation to blood volume. The skeletal muscles are predominantly slow twitch in type, developing an unusual force and power at low contraction velocities. Many rowers have a suboptimal diet, eating excessive amounts of fat. Lightweight rowers also have problems of weight cycling. Aerobic power and muscle endurance often change by 10% over the season, but such fluctuations can be largely avoided by a well-designed winter training programme. Injuries include back and knee problems, tenosynovitis of the wrist and, since the introduction of large blades, fractures of the costae.     

我国体育市场管理法规研究

采用调查法和比较法对全国体育市场立法和管理现状进行调查,对部分较早出台并有一定代表性的省市的体育市场管理法规的立法和管理情况进行了研究,提出了体育市场管理立法和管理的原则、基本程序、措施及其一般模式,为规范全国体育市场管理提供参考依据。     

重新认识体育的社会关联

体育与政治之间存在一个悖论，体育的发展与经济实力之间没有直线相关，体育与教育部分重叠，体育与宗教最为近缘，体育可借用科学手段，体育的艺术禀性日益明显，体育与养生反映着两种人生观。     

上海社区体育竞赛参与者的特点探析

本文在专家访谈、问卷调查、数理统计和文献资料分析的基础上,探析了上海社区体育竞赛参与者的特点、参与者对社区体育赛事运作管理的看法等问题。在此基础上从引进社区体育赛事的志愿者、整合社区体育赛事的各种资源、开发社区体育竞赛的无形资产、组建非营利性的专业团队、规范社区体育赛事的服务管理等方面提出了进一步满足上海社区居民日益增长的体育竞赛参赛需求的对策与措施。     

对全面把握游泳训练环节的探讨

从系统观点出发,结合训练实践,对全面把握游泳训练环节进行探讨。认为应强化非智力因素在运动员多年训练中的作用,在育材全过程中不断选材,从整体上把握动态训练的全过程,把培养高水平运动员的整个过程置于一个严格的科学控制之下。     

我国优秀游泳运动员出发技术辅助训练的研究

为改进我国优秀游泳运动员的出发技术,采用观测和实验方法,通过拍摄运动员陆上和水下出发技术录像以及出发计时,对出发技术进行运动生物力学诊断和分析。在此基础上,根据运动员自身特点和不同泳姿提出相应的入水启动方式,并研制出发训练辅助器材,对出发预备姿势、腾起角度以及飞行远度和入水角进行控制。实践证明:这是一种快捷、有效的出发技术辅助训练方法。     

运动性呼吸肌疲劳与耐力性项目的运动能力

影响和限制耐力性运动项目的成绩的生理因素是复杂的和多方面的,取决于训练的强度和运动成绩.大强度持续性运动可导致呼吸肌疲劳.运动性呼吸疲劳可能在决定运动耐量方面起到关键的作用：一方面通过直接影响运动肌力量的生成（外周疲劳）,另一方面,通过肢体用力自感不安反馈引起工作肌运动单位输出功率下降（中枢疲劳）.对呼吸肌进行训练,可能有助于提高耐力性项目的运动成绩.     

Identifying home advantage in international tennis and golf tournaments

A regression analysis of competitors' tournament results in relation to their world rankings was proposed to identify the effect of home advantage in international ‘grand-slam’ tennis and ‘major’ golf tournaments. The results provided little evidence of home advantage in either the grand-slam tennis or the golf tournaments held in 1993. The only possible evidence of home advantage was found in the Wimbledon tennis and the US Open golf championships. Even these findings can be explained, at least partially, by (1) the availability of information concerning the low world rankings of the British tennis players competing at Wimbledon, and (2) selective entry, allowing only the world's top-ranked foreign golfers into the US open golf tournament. In both cases, the lower ranking home competitors have a greater opportunity to perform above their anticipated world rankings. Therefore, provided entry into tennis and golf tournaments is truly ‘open’ to both the host nation's representatives and foreign competitors alike, home advantage does not appear to be a major factor influencing the competitors' performance in such competitions. These findings may be explained by the relatively objective nature of the scoring systems used in tennis and golf, unlike the subjective influence of refereeing decisions on the results of team-games such as soccer.     

对欧洲足球技战术发展趋势的思考

结合欧洲足球技战术的发展特点,就鲁能泰山足球队的体能训练、技术训练、防守阵型、进攻方式、定位球、职业态度、球星培养等诸方面所存在的不足进行了分析,提出相应的改进意见。