电动跑台对提高竞走运动员步频的研究

采用竞走运动员无氧阈值速度的测定与应用方法 ,分别对运动员进行 3个阶段逐级提高速度的跑台竞走实验 ,经过统计学处理和实际比赛的对比 ,结果表明 :利用电动跑台进行辅助训练 ,可以加快发展竞走运动员的动作速率 ,有效提高竞走运动员的步频 ,创造优异成绩。     

The density of social networks moderates effects of intergroup contact

This study tests how the density of the social network in which intergroup contact takes place might affect the extent to which contact improves intergroup attitudes. Having contact with more outgroup members in dense social networks, in which everybody knows each other, may reinforce contact's positive effect. In this case, outgroup contact is shared with ingroup members, which suggests positive ingroup norms toward the outgroup. Alternatively, more contact in denser networks may improve intergroup attitudes less because density may increase subtyping or reduce the salience of ethnic group memberships. These competing hypotheses are tested among white American adults in a nonprobability online sample (N = 305) and in a representative national sample (N = 1270). In both studies, contact is associated with more positive attitudes toward racial outgroups but the positive contact effect is weakened if that contact takes place in a denser social network.     

论强国富民离不开美育

美育有助于提高生产力.从社会的发展趋势来看,美育和科学技术愈来愈紧密地融合.美育和科学技术融合有深厚的理论基础.培养人才离不开美育,美育和创造性人才有内在的心理联系.将美育真正融入学校、家庭、社会,全面提升学生素质是切实可行的.     

关于变频调速的应用与节能分析

文章通过分析变频器调速的节能原理,并结合一个热电厂的变频器改造后的实例,阐述了变频调速的节能效果,提高了设备运行可靠性和节能降耗性。     

氧化还原滴定反应计量点电势通用计算公式探讨

对氧化还原滴定反应计量点电势的通用计算公式进行了具体深入的探讨,对公式作了准确表述和具体证明.该通用计算公式能解决对称电对、不对称电对和有H+参加的氧化还原滴定反应计量点电势的计算.     

Simulation of Fragment Impact on Multi-Layer Targets Using Contact Method

Cased explosives generate highly energetic fragments as their casing breaks up. Due to the complexity of casing fragment related behavior such as embedment, perforation and ricochet, it may be insufficient to use equivalent triangular pressure loading in fragment impact simulations. This simplified method may over- or under-predict the target response. Recently, a procedure using contact techniques has been proposed to overcome such difficulties. It has been shown that the new method has the inherent capability in modeling the multi-piece and multi-hit fragment impact problems in a more realistic way. To investigate the applicability of the proposed method to simulations involving multi-layer penetration, the selected problems of fragment impact on multi-layer targets are described in this paper. It is demonstrated that this method is capable of predicting the complicated multi-layer structural response caused by fragment impact and penetration. Modeling procedures and some technical issues are also discussed.     

电磁场──物质的基本形式之一

电磁场是物质的基本形式之一，它无需电荷激发，而是自然界固有的；电荷只是为了描写电磁场而引入的一过渡量．并由此提出了一个计算电子电能的设想．     

局部热处理工艺在大型主轴中的应用

在机械制造过程中，对大型工件进行退火处理都有一定难度，而对结构紧凑、不同组件又有不同的性能要求的大件进行退火处理更加困难，如何克服对主件处理时不影响其它组件的性能呢?本文采用陶瓷电加热器进行局部热处理的方法，较好地解决这一难题，具有普遍的借鉴意义。     

板式电位差计与箱式电位差计的区别与联系

通过分析两种电位差计的结构，讨论了它们在实际应用中的区别与联系。     

谈双电桥的灵敏度

通过理论和实验两个方面,讨论了如何测量双电桥的灵敏度及影响双电桥灵敏度的因素.