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传统PID控制在串级控制系统中当被控对象发生变化时,主控制器的参数难以自动调整。针对串级控制系统被控对象大惯性、不确定特点,提出将模糊控制与PID控制结合,在串级控制系统中将主控制器采用自适应模糊 PID控制技术,使主控制器具有较好的自适应性。使用MATLAB对系统进行仿真,结果表明在串级控制系统的主控制器中用自适应模糊控制 PID控制器来取代传统常规 PID控制器后,整个串级控制系统具有良好的动态性能。当被控对象模型结构发生变化时,控制系统的抗干扰性及鲁棒性得到较大的提升。 相似文献
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影响武术散打运动员赛前状态焦虑因素的分析 总被引：1，自引：0，他引：1
采用心理测量问卷调查法、多因素方差分析、相关分析法、访谈法对参加2010年8月在陕西宝鸡举行散打冠军赛的120名运动员进行赛前状态焦虑分析。结果表明：（1）有大赛经验运动员在处理赛前状态焦虑方面要强于无大赛经验运动员。（2）武英级运动员认知焦虑与躯体焦虑均低于一级和二级运动员的这两项指标,并且状态自信心高于其它两个等级运动员的状态自信心。（3）武英级运动员与一级、二级运动员比较,在赛前状态焦虑的三个维度上均显示显著性差异;并且认知焦虑是影响武术散打比赛的一个主要焦虑。（4）赛前状态焦虑还与运动员的心理疲劳与运动损伤的影响因素、对手的水平差距、领导与教练员的影响因素等这些因素相关。 相似文献
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12、弓步劈斩
左脚侧上步成左弓步，右脚发力蹬腿；同时，右手提刀至头上向右后下方劈出，再向前提撩斩出，左手将后刀压下再向上挑刀，并收至腰间，藏于腋下。（图12） 相似文献
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运动表象是运动员在训练和比赛中广泛使用的一种非常有效的心理训练方法,也是研究者十分关注的重要研究主题。研究采用EEG来对运动表象进行测量,从心理生理学的角度探索专家与新手之间的差别,研究得出：专家与新手之间安静状态下大脑的神经活跃程度相似,并未因训练不同而产生差异。在运动表象过程中大脑左右半球并没有出现大脑侧性优势。运动表象时专家与新手的差异性出现与运动相关的区域,δ波在左额极区（FP1）、左中央区（C3）、左顶区（P3）;α波在左中央区（C3）和左顶区（P3）、右顶区（P4）和左枕区（O1）;β波在右顶区（P4）存在显著性差异,其皮层激活在左侧区域分布广泛。运动表象过程中α波增加而不是受到抑制,在视觉表象中出现α波抑制。 相似文献
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本文主要阐述触摸屏技术在西门子PLC模拟量控制变频器调速系统中的应用。采用PLC模拟量控制变频器,方法简便、调速性能较好,再引入触摸屏控制技术,就能使控制系统的交互信息更为丰富、控制功能更为全面、操作方法更为简便。本文将以西门子PLC、变频器及触摸屏为例阐述上述系统的基本设计方法。 相似文献
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以第39和40两届世界体操锦标赛的女运动员为研究对象，对北京奥运会女子自由体操比赛特点进行分析研究。结果显示：成套动作的难度（A分）平均为6．2分，最高为6．5分，继续发展动作难度的空间较小；每套动作平均包括4个高难度技巧（串）动作，其中单个技巧动作的难度略有增加，而技巧串动作难度接近持平；裁判对动作质量要求更加严格，只有提高完成动作的规格标准和稳定性，才能获得优异成绩。 相似文献
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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. 相似文献
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Roy J. Shephard 《Journal of sports sciences》2013,31(7):603-620
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. 相似文献
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Alan M. Nevill Roger L. Holder Andrew Bardsley Helen Calvert Stephen Jones 《Journal of sports sciences》2013,31(4):437-443
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. 相似文献
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许良 《体育科技文献通报》2011,19(2):1-4
基于1985、1995和2005年全国学生体质调研数据,对各时期我国城乡学生形态、机能、体能发展水平进行系统地定量研究,动态分析20年全国城乡学生体质发展的特点与规律。主要研究结果：（1）近20年城乡学生生长发育持续提前,城市学生各项形态指标生长水平高于乡村,身高城乡差距缩小,体重、胸围城乡差距加大;（2）城市学生肺活量水平高于乡村,城乡学生肺活量20年持续下降,前10年乡村学生下降快、后10年城市学生下降快;（3）乡村学生800m、1000m跑水平高于城市,城市女生50m跑、仰卧起坐水平高于乡村,其他素质城乡学生水平波动较大;（4）城市女生50m跑20年持续下降,城乡学生800m和1000m跑、城市学生50m×8往返跑20年加速下降,其他素质20年间有增有降发展极不平稳。 相似文献
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采用测量、问卷调查、数理统计等方法,分析定向运动学习前后对大学生身心健康的影响.结果经T检验和x2检验且表明：定向运动不仅能增强学生体质健康水平,而且有助于学生的情绪调节,增强自信心与创新意识,培养勇敢顽强的意志品质,建立良好的人际关系,能有效地促进学生身心健康发展.为了全面提高大学生整体素质,积极实践,构建定向运动课内外一体化教学模式,进行定向运动课程模块化教学,以满足学生的多元化需求. 相似文献
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重新认识体育的社会关联 总被引：3，自引：1，他引：2
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。 相似文献
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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。 相似文献
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对全面把握游泳训练环节的探讨 总被引：4，自引：0，他引：4
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。 相似文献