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PC-6“搬运工”(Porter)是瑞士研制生产的一种多用途短距起降轻型飞机，在越战时被美军广泛使用。其出色的起降能力和可靠的性能广受好评，并发展了多种改型，有的型别一直使用到现在。宽大的低压轮胎和占翼展一半的襟翼是它的特色。简洁的线条、长长的机头使它很容易与其它飞机区分。 相似文献
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平均故障间隔时间和签派可靠度是民用飞机最重要的可靠性指标,其直接反映飞机可靠性水平的高低。根据民用飞机各系统之间的架构关系和基本可靠性的特点,考虑飞机系统结构特点以及系统的工作环境等因素,给出民用飞机可靠性指标的预计模型和方法。 相似文献
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本文结合城市燃气管网运行以及发展的动态趋势,针对管网全寿命周期内从生产设计到投产运行,故障维修再至失效更换各个环节的可靠性予以考虑分析,提出了燃气管网安全运行的方法以及故障维修的措施,分析了影响城市燃气管网系统可靠性的因素,并列举出管网每个阶段提高其可靠性的建议与措施。 相似文献
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针对当前电梯故障频发的现状,本文分析了电梯故障监测系统,包括运行状态监测和远程报警系统,为维修管理人员准确判断故障并及时采取相应措施提供信息,提高电梯运行的安全性和可靠性。 相似文献
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核电厂设备数量多、结构复杂,许多设备故障与运行时间并无直接关系,不能简单通过定期维修来避免这些设备失效。为了提高设备的可靠性和可用率,降低设备维修成本,对核安全、机组发电有重要作用的设备,进行设备状态监测,根据检测结果开展预测性维修工作。按照设备的特点,采用合理的设备状态监测方法、内容和频度,发现设备潜在的故障,可以及时安排对潜在问题设备进行预测性维修,提高设备维修管理水平。 相似文献
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直接维修成本是衡量民用飞机维修性和经济性的重要指标,飞机直接维修成本目标值的预计对于实现飞机全寿命周期维修成本控制具有重要意义。本文基于欧洲98法对民用飞机直接维修成本目标值的预计进行了研究。 相似文献
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越来越多的电子产品在汽车制造中不断引入使用,带动了汽车维修行业修理保养方式的转变,汽车维修已经不再是简单的零件修复。提前预知故障的发生,在发生故障之前解决故障,发生故障之后能快速而又准确无误地诊断出故障所在是现代汽车维修的最高境界。 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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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
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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. 相似文献
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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。 相似文献
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朱新新 《体育科技文献通报》2010,18(3):52-53,57
本文运用文献资料法,逻辑分析法,在遵循逻辑学、哲学、心理学原理的前提下,对竞技健美操技术的概念进行了界定,对竞技健美操技术进行了分类研究,在此基础上分析了竞技健美操技术的结构,为系统、科学的组织竞技健美操的教学和训练提供理论上的参考,为促进竞技健美操理论体系的完善和协调发展做出一定的贡献。 相似文献