曲轴线抛光工艺及原理分析

SGMW青岛发动机工厂曲轴线抛光工位采用的是德国Supfina抛光机,该工位是曲轴加工环节中最后一个工位,主要对曲轴的主轴颈、连杆颈、油封以及止推面进行精抛光,这样就保证了曲轴表面的光洁度.抛光工位的稳定性会对曲轴的腰鼓度、锥度等质量特性产生重要影响,如何保证加工中腰鼓度、锥度是否满足产品性能要求,是影响抛光机开动率的一项重要因素.本文介绍了曲轴抛光机的基本结构,加工原理,并结合实际生产进一步探讨解决发动机曲轴加工精度的方法,使加工质量得到有效提升.     

汽车车灯面罩模具竖纹的三轴加工创新

汽车车灯面罩模具竖纹的加工一般要在五轴的数控机床上才能完成,本文对该模具的数控加工工艺进行了详细分析,提出了加工创新方法,引入机床角度头,用三轴的数控机床完成了车灯面罩模具竖纹的加工,大大降低了实际生产成本,同时也保证了产品加工质量。     

1000MW核电厂循环水泵选型分析

循环水泵的配置关系到整个核电的初期投资和后续的经济效益。随着国内核电的发展,机组功率的不断增加,对循环水泵容量和可靠性要求更高。常用的循环水泵主要为混凝土蜗壳泵和金属混流泵。本文根据不同循环水泵选型方案的列举和筛选,同时结合厂址的水温条件对核电站的循环水泵配置进行分析和选择。     

半轴端盖夹具设计

在制造业中,夹具是产品在制造各个工艺阶段中地位处在非常重要的工艺装备之一.在生产中,厂家所使用到的夹具的工作效率、质量、精度及夹具的使用的可靠性和安全性,都会对所要生产的产品的加工质量及生产效率造成决定性的影响.因此夹具选择,使用对于厂家非常重要.夹具用于对加工对象的固定,使工件处在正当的加工位置上,以便于下一步的加工需要.夹具的类型分为普通夹具,专用夹具,组合夹具,标准夹具,可调夹具等.本文是针对半轴轴承套设计的专用夹具,主要参考了《机床夹具设计》和《机床夹具及应用》里面所介绍的一系列方法,并大量查阅了《机床夹具设计手册》中的设计参数从而设计出来.通过对夹具进行合理化的设计,保证夹具的精度,可靠性和生产率.     

论机械装配的工艺基础分析

机械装配是整个机械加工过程中的最后一个阶段,该阶段工作完成的效率和质量,直接影响到整个机械产品的质量和企业生产该种机械产品的成本.同时,人们在进行机械装配时,还会对在生产该机械产品时所用到的工艺的质量进行检测,以纠正和解决机械产品在设计、加工、制造过程中所出现的问题,提升产品的质量.本文就机械装配的工艺基础进行简要的分析.     

运动性疲劳动物模型的研究

通过文献资料调研,论述了运动性疲劳动物模型的分类依据及建模方法;在分析已建模型的基础上,探讨了建立标准化的运动性疲劳模型的质量控制问题。     

基于等效焓降法300MW热电联产机组热经济性分析

热电联产符合能源梯级利用的原理,具有节约能源、改善环境质量、缓解电力需求压力、提高供热质量等优越性。300MW热电联产机组是未来发展的重点,用等效焓降法对300MW热电联产机组进行变工况计算,分析抽汽量和抽汽压力对机组热经济性的影响,对机组的实际运行具有重要的指导意义。     

线切割加工中电极丝的选用及断丝分析

电火花线切割是精密与特种加工重要组成部分,影响线切割加工的因素很多,而切割效率和切割质量与线切割加工中电极丝的性能紧密相关.本文对电火花线切割加工中电极丝的性能、选用,以及加工中断丝的原因、预防进行分析,从而提高电火花线切割效率和加工质量.     

“狠抓产品质量,挺起民族企业的脊梁”(之二)——浅析光威集团的质量意识

(接上期)同时,光威集团注重提高全体员工的素质。人的素质决定产品的质量,再好的质量保证体系也需要人来实施,质量再好的产品也需要人来加工生产。为了提高员工的整体素质,光威集团采取了“外聘内训”的用人原则,极大地促进了人力资源的素质升级。“外聘”,就是用优厚的条件吸引那些对企业发展能有重要贡献的或者愿意来光威工作的大中专毕业生和各类技术工人,至今已招聘了600多名骨干力量,积聚了企业的发展动力;“内训”是指对光威集团内部职工加强质量意识教育和技术技能教育,光威对员工进行了全方位的培训。光威集团对质量监督人员的要求…     

浅谈参与机组协调控制有功功率变送器的优化

机组的实际负荷即实发功率是机组协调控制系统中的重要组成部分,现代大型发电机组一般都采用有功功率变送器来测量机组的实发功率,这无疑就给参与机组协调控制的有功功率变送器本身的质量、回路的可靠性和DCS逻辑的组成提出了更高的要求。本文介绍了几起由于有功功率变送器本身和回路故障而引起的异常事件,详述了为保证参与机组协调控制有功功率变送器的安全可靠运行,在其回路及DCS逻辑组成上所做的优化方案。     

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。