模型汽油机电子点火装置DC-CD1原理和工艺

近年来,国内模型汽油机生产厂家如雨后春笋般层出不穷。与甲醇机相比,二行程汽油机稳定性好．怠速低、价格便宜、飞行成本不高,已披越来越多的模型爱好者采用。但国产汽油机在最大输出功率、油门响应,工作稳定性,抗干扰能力等方面．与进口同类汽油机还存在一些差距。究其原因,除设计和生产工艺差别外．汽油机的点火装置也是重要影响因素。     

在中国举行的首次汽车拉力赛

十九世纪末到二十世纪初,是世界工业飞速发展的时期。作为现代人主要交通工具的汽车工业,在这个时期诞生并迅猛发展起来。１８８６年,德国人本茨在蒸汽三轮汽车的基础上改造发明了汽油机汽车,这是汽车发展史上的一次飞跃。汽油机的诞生使得汽车的行驶速度更快,运行的...     

介绍一台国产汽油机的改装、使用与保养

在山东省临沂市某公司生产的系列汽油机中，IE33F型汽油机最能吸引航模发烧友中DIY一族的青睐。其漂亮的外观设计，精致小巧玲珑；合理的结构设计，给人坚固耐用的良好印象；优化的结构布局，保证了该机运转的稳定性和耐久性；整机振动轻微、噪音低；而且省油、性价比高。因此，笔者选择把该机改装成模型飞机发动机。     

小型汽油机测功台架设计

本文介绍的试车平台是针对小型汽油机出厂检测设计,集功率、转速、油耗测试为一体,并通过快速装夹机构,操作方便,能提高试车可靠性.     

读者来信

你们好!我是黑龙江省牡丹江市的一名普通航模爱好者,现已七十高龄,连续订阅《航空模型》十年了。通过阅读贵刊,使我比较系统地掌握了与航模相关的各方面知识,逐渐学会独立设计、制作、放飞、修理各种模型飞机。迄今为止,我已制作各式遥控模型飞机22架：从动力系统上分,有电动机、汽油机、甲醇机等;从气动布局上分,有上单翼机、下单翼机、双翼机等。     

汽车用柴油机、汽油机匹配变速器技术差异性分析

动力性是汽车各种性能指标中最基本、最重要的性能,汽车运输效率之高低在很大程度上取决于汽车的动力性.因此,研究不同类型发动机匹配变速器的合理性是各大主机厂的首要任务.本文在分析柴、汽油机性能特征的基础上,得出车辆匹配不同类型发动机对传动系、变速器性能指标的影响,并通过实例计算,证明理论分析结果.     

石材加工行业存在的职业病危害因素分析及对策措施

本文识别了石材行业主要工艺过程存在的职业病危害因素,根据工艺特点分类归纳出了石材行业重点控制的职业病危害因素为:化学因素(生产性粉尘)、物理因素(噪声、振动、电击、切割),明确了重点职业危害因素的控制场所,并提出了相应的危害防护措施,为石材加工企业预防、控制和消除职业病发挥重要的参考作用.     

酸雨

酸雨对人类有极大的危害,它使湖泊水质变酸而危害鱼类,使土壤酸化而危害农作物,毁坏森林,腐蚀建筑,还能危害到人体健康,被人们称为“空中死神”。 酸雨的产生主要是由于人类在工业生产、交通运输和日常生活中所产生的二氧化碳、氮氧化合物等废气排放到空气中,到了一定高度,和水蒸汽结合形成弱酸,遇到降雨,随同雨水一起降落到地表,对人类产生危害。     

有关蔬菜农药残留问题的探讨

蔬菜水果中的农药残留问题成为人们关注的焦点。本文就蔬菜农药残留的危害,结合相关资料和实际情况介绍了人们减少蔬菜农药残留危害的方法。     

“油”改“电”——改造一架油动3D模型飞机

电动模型飞机以其环保、低噪音等优点正在逐步发展起来，前景可观。无刷电机、锂聚合物电池的出现更加速了电动模型飞机的发展。在刚刚落下帷幕的2005年法国世界F3A锦标赛的100多架参赛模型飞机中，有30余架电动模型飞机，并且取得了不错的成绩。电动模型飞机正以它的各项优势，冲击着内燃机动力模型飞机。甚至有些以汽油机为动力的模型飞机也被改装成了电动动力，性能一点也不逊于内燃机动力（如图1）。     

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。