体育的社会安全阀效应     

夏源江  杨春生  张旭昌 《唐山师范学院学报》2010,32(5):122-124

运用社会学有关社会稳定的相关理论,分析体育在社会平稳运行中的安全阀效应。结果表明：（1）释放社会压力,将敌对和不满的情绪发泄到体育攻击对象上。（2）转换释放压力的对象,发挥体育替代目标的作用．（3）增强社会成员的凝聚力和归属感,缓和社会矛盾。（4）为青少年提供剩余精力的发泄渠道,减少青少年犯罪率。（5）陶冶情操、促进人际关系的改善,维护社会的和谐稳定。  相似文献   

Time course of recovery of vertical jump height and heart rate versus running speed after a 90-km foot race     

Alan M Nevill  Roger L Holder  Arthur D Stewart 《Journal of sports sciences》2013,31(7):645-650

It is well known that sport and exercise play an important role in stimulating site-specific bone mineral density (BMD). However, what is less well understood is how these benefits dissipate throughout the body. Hence, the aim of the present study was to compare the BMD (recorded at nine sites throughout the skeleton) of 106 male athletes (from nine sports) with that of 15 male non-exercising age-matched controls. Given that BMD is known to increase with body mass and peak with age, multivariate and univariate analyses of covariance were performed to compare the BMD of the nine sports groups with controls (at all sites) using body mass and age as covariates. Our results confirmed a greater adjusted BMD in the arms of the upper-body athletes, the right arm of racket players and the legs of runners (compared with controls), supporting the site-specific nature (i.e. specific to the externally loaded site) of the bone remodelling response (all P?<0.01). However, evidence that bone mass acquisition is not just site-specific comes from the results of the rugby players, strength athletes, triathletes and racket players. The rugby players' adjusted BMD was the greatest of all sports groups and greater than controls at all nine sites (all P?<0.01), with differences ranging from 8% greater in the left arm to 21% in the lumbar spine. Similarly, the strength athletes' adjusted BMD was superior to that of controls at all sites (P?<0.05) except the legs. The adjusted BMD of the triathletes was significantly greater than that of the controls in both the arms and the legs as well as the thoracic and lumbar spine. The racket players not only had significantly greater right arm BMD compared with the controls but also a greater BMD of the lumbar spine, the pelvis and legs. In contrast, the low-strain, low-impact activities of keep-fit, cycling and rowing failed to benefit BMD compared with the age-matched controls. These results suggest that sporting activities involving high impact, physical contact and/or rotational forces or strains are likely to convey significant benefits not only to the loaded sites, but also to other unloaded peripheral and axial sites throughout the skeleton.  相似文献   

一种低功耗电磁阀控制电路的改进分析     

赵晓平 《科教文汇》2013,(6):94-95

电磁阀是液压、气动系统中应用最普通、最典型的控制元件。传统控制方式能耗高,电磁铁温升高。本文采用吸合一维持分别控制的方式,即吸合过程为电磁铁施加额定电流,而维持阶段为PWM控制方式,将维持阶段的平均电流降至额定电流的30％以下,实现电路简单、工作稳定可靠。  相似文献   

电液比例变量泵的测试     

丁英丽 《辽宁科技学院学报》2003,5(3):21-22

主要介绍了双边联合控制的电液比例变量泵的工作原理，设计了基于单片机的测试系统，并利用此测试系统对电液比例变量泵的静态特性进行了潮试和计算机仿真。  相似文献   

新型磁电阻效应实验仪研制及应用     

倪敏  许美新  时晨 《实验技术与管理》2012,29(5):76-79

利用新型的磁电阻效应实验仪对多层膜巨磁电阻传感器、自旋阀巨磁电阻传感器以及各向异性磁电阻传感器的电阻随外加磁场的变化进行了研究,从而了解各种磁电阻的特性。该新型仪器可在高校实验中应用,有助于学生掌握磁电阻传感器的定标方法,测量并计算3种磁电阻传感器灵敏度,也可用于研究3种磁电阻传感器输出电压与通电导线电流的关系,以及磁电阻的其他效应。  相似文献   

High cycle fatigue life prediction and reliability analysis of aeroengine blades     

张俊红  林杰威  张桂昌  刘海 《天津大学学报(英文版)》2012,18(6):456-464

Based on the nonlinear continuum damage model(CDM) developed by Chaboche,a modified model for high cycle fatigue of TC4 alloy was proposed.Unsymmetrical cycle fatigue tests were conducted on rod specimens at room temperature.Then the material parameters needed in the CDM were obtained by the fatigue tests,and the stress distribution of the specimen was calculated by FE method.Compared with the linear damage model(LDM),the damage results and the life prediction of the CDM show a better agreement with the test and they are more precise than the LDM.By applying the CDM developed in this study to the life prediction of aeroengine blades,it is concluded that the root is the most dangerous region of the whole blade and the shortest life is 58 211 cycles.Finally,the Cox proportional hazard model of survival analysis was applied to the analysis of the fatigue reliability.The Cox model takes the covariates into consideration,which include diameter,weight,mean stress and tensile strength.The result shows that the mean stress is the only factor that accelerates the fracture process.  相似文献   

论单位商品价值量下降规律——回应“成正比”争议的第2个命题     

余斌  沈尤佳 《教学与研究》2012,(3):56-62

成正比的争议涉及两个命题:一是,一定长度的工作日总是表现为相同的价值产品。二是,劳动生产率提高,单位商品价值量下降。本文回应的是关于第二个命题的争议。在这个问题的争议中,认为在劳动生产率提高时,劳动生产率与单位商品价值量成反比的规律将不再成立的人,即主张"成正比"的人,其论证的主要依据是建立在劳动生产率等于劳动复杂程度和劳动强度的假设上的。然而这个假设是不成立的。社会劳动生产率的水平本身"表现为一个工人在一定时间内,以同样的劳动力强度使之转化为产品的生产资料的相对量。"其与劳动强度和劳动的复杂程度没有直接的关系,甚至在很大程度上劳动生产率与劳动复杂程度是成反比的。更为重要的是,市场竞争是通过使商品便宜而不是使商品昂贵来进行的。如果劳动生产率的提高使得单位商品价值提高从而使商品变得昂贵,那么,资本家就不会用提高劳动生产率的方法来进行竞争。显然,这不是事实。  相似文献   

高炉煤气余压能量回收透平发电装置应用研究     

黄丽燕  陈虎 《闽西职业技术学院学报》2012,14(1):96-99

介绍了高炉煤气余压能量回收透平发电装置的应用,包括工艺流程、仪控自动控制系统的原理、安装过程中的故障处理、目前存在的问题及应用前景.  相似文献   

苏格兰议会的选举制度     

张文玲 《思茅师范高等专科学校学报》2012,28(1):31-34

英国长期以来都实行的是简单多数选举制度,自1997年工党上台之后,进行了大刀阔斧的权力下放改革。苏格兰开始实行简单多数制与比例代表制并存的混合选举制度。新的选举制度对政党格局、政府决策等都产生了深刻的影响,也为威斯敏斯特议会的选举方式改革提供了新的思路。  相似文献   

远距离输电系统大型发电机汽门开度最优控制     

周安锋  刘志泽 《华章》2012,(22)

在对远距离输电系统大型汽轮发电机调速中,汽门开度影响发电机的输出功率和转速,从而影响系统的稳定性。利用最优控制理论方法设计出汽门开度最优控制器,通过对汽门开度控制的仿真,研究了控制过程中发电机的输出功率特性、转速特性及其对电力系统的影响。结果表明,汽门开度最优控制对改善电力系统稳定性和抑制低频振荡有着重要作用,可以很大程度地改善系统的动态性能。  相似文献