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电网调度是电网安全、稳定和经济运行的重要保障,通过调度操作命令的形式改变电网运行方式、设备状态和调整经济运行,无论是日常工作还是事故异常处理,调度员发布的每道调度操作命令都必须是正确的,这就要求调度员必须严格执行各种规程和规章制度,避免误操作、误调度事故的发生,确保人身、电网和设备安全。 相似文献
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从经过几十年世界核电厂以及30多年中国核电厂的发展来看,核电是一种既清洁又安全的能源,但是当世界上最严重切尔诺贝利核电站泄漏事故的产生,让人们意识到虽然核电厂的事故发生概率很低,但因为所带来的后果是十分严重的,因此需要加强核电厂安全的重视,本文就以电厂变压器的安全和调试进行分析,以此为保证其安全可靠性提供帮助. 相似文献
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继电保护可以使系统安全运行,防止事故的发生和故障的扩大,使电力系统的重要组成部分.但在实际工作中,保护装置偶尔会出现拒动和误动的现象,减少继电保护的可靠性,对稳定的电力供应构成了威胁.通过对继电保护的可靠运行进行探讨提高电网安全稳定性. 相似文献
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由于棒控系统直接关系到机组运行时反应堆正常的反应性控制和负荷跟踪,而且棒控系统的不正常工作直接影响核电站的安全稳定运行,严重的可导致保护动作,造成停堆等事故的发生.因此,本文论述了二厂一/二号机组棒控系统内部的相关报警产生的原因和对机组正常运行的影响,以及运行人员应做出的响应和处理方法. 相似文献
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针对近期某电厂汽轮发电机组因轴承振动大导致的机组恶性事故,汽轮发电机组的轴承振动大保护已不能单靠运行人员根据运行经验来决定是否采取措施,本文则介绍了汽轮机振动大保护优化的方法,分别实现机组并网前后实时准确的保护投入,避免人为因素导致机组事故的发生,保障机组的安全稳定运行. 相似文献
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继电保护是保证电力系统安全稳定运行的重要手段。电流互感器的饱和问题是目前导致微机继电保护装置误动的主要原因。因此,电流互感器10%误差曲线的绘制及校核工作是继电保护专业必须完成的工作。但是,现实中很多电厂由于多种原因,并未开展此项工作,机组在运行中存在着很大的安全隐患。本文就针对发电厂电流互感器10%误差曲线的绘制及校核过程中遇到的具体问题进行了介绍。 相似文献
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随着我国电网快速发展,对无人值守变电站的监控质量提出了更高要求.但大量无用、无效、错误的信息上传容易造成监控员麻痹大意,遗漏重要的设备监控信息.恶劣天气下或电网事故异常处理时,也会严重影响监控值班员对监控的信号快速判断,对汇总排查重要信号造成干扰,降低快速处理事故异常的时间.为保证电网安全运行,保证电网设备的监控质量,因此,监控信号治理工作势在必行.针对监控信息中的无用、无效、错误信号进行治理通,力求在最大程度上消除监控垃圾信息,提高电网运行安全稳定水平,提升监控员事故处理分析能力,促进监控运行管理水平再上新台阶. 相似文献
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控制棒组件(Rod Cluster Control Assembly)简称RCCA,在正常运行时用于调节反应堆功率,在事故工况下快速引入负反应性,使反应堆紧急停堆,保证核安全。随着核电站运行周期的增加,RCCA长期处在高温、高放射性、往复机械运动的特殊工况下,金属材料热老化现象、RCCA与导向管的接触磨损工况,均会导致服役一定时间的控制棒组件产生磨损、肿胀裂纹等缺陷。本文主要论述了RCCA可能产生的缺陷及分析、RCCA肿胀机理、RCCA肿胀部位以及肿胀时间。 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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青少年业余足球运动员运动倾向性5因素结构模型初探 总被引：3，自引：0，他引：3
根据Scanlan等人最新提出的运动倾向性理论模型,结合我国实际情况建立了青少年足球运动员运动倾向性5因素结构模型。运动倾向性被定义为:渴望和决心继续参加足球运动的心理状态。所建立的5因素结构模型认为,运动倾向性是由运动乐趣、参与选择、个人投入、社会约束及参与机会5个因素决定。经确定5个决定因素和运动倾向性的操作定义,编制了相应调查问卷,通过对北京市252名青少年足球运动员实测结果,建立运动倾向性及其影响因素的协方差结构模型,用Lisre 18分析的结果表明:该运动倾向性模型比较符合北京青少年足球运动员。其中运动乐趣、个人投入、参与机会和参与选择4因素对运动倾向性有影响;社会约束对运动倾向性影响不大。 相似文献
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The aim of this study was to assess the sensitivity of the lactate minimum speed test to changes in endurance fitness resulting from a 6 week training intervention. Sixteen participants (mean +/- s :age 23 +/- 4 years;body mass 69.7 +/- 9.1 kg) completed 6 weeks of endurance training. Another eight participants (age 23 +/- 4 years; body mass 72.7 +/-12.5 kg) acted as non-training controls. Before and after the training intervention, all participants completed: (1) a standard multi-stage treadmill test for the assessment of VO 2max , running speed at the lactate threshold and running speed at a reference blood lactate concentration of 3 mmol.l -1 ; and (2) the lactate minimum speed test, which involved two supramaximal exercise bouts and an 8 min walking recovery period to increase blood lactate concentration before the completion of an incremental treadmill test. Additionally, a subgroup of eight participants from the training intervention completed a series of constant-speed runs for determination of running speed at the maximal lactate steady state. The test protocols were identical before and after the 6 week intervention. The control group showed no significant changes in VO 2max , running speed at the lactate threshold, running speed at a blood lactate concentration of 3 mmol.l -1 or the lactate minimum speed.In the training group, there was a significant increase in VO 2max (from 47.9 +/- 8.4 to 52.2 +/- 2.7 ml.kg -1 .min -1 ), running speed at the maximal lactate steady state (from 13.3 +/- 1.7 to 13.9 +/- 1.6 km.h -1 ), running speed at the lactate threshold (from 11.2 +/- 1.8 to 11.9 +/- 1.8 km.h -1 ) and running speed at a blood lactate concentration of 3 mmol.l -1 (from 12.5 +/- 2.2 to 13.2 +/- 2.1 km.h -1 ) (all P ? 0.05). Despite these clear improvements in aerobic fitness, there was no significant difference in lactate minimum speed after the training intervention (from 11.0 +/- 0.7 to 10.9 +/- 1.7 km.h -1 ). The results demonstrate that the lactate minimum speed,when assessed using the same exercise protocol before and after 6 weeks of aerobic exercise training, is not sensitive to changes in endurance capacity. 相似文献