汽车离合器基本参数的优化设计     

王萌 《十堰职业技术学院学报》2000,13(2):46-49

汽车离合器的基本参教主要有离合器的后备系数β、摩擦面单位面积上的压力p0、摩擦片外径D和内径d等,这些参教的变化直接影响离合器的结构尺寸和工作性能。本采用优化设计方法来确定最佳的离合器基本参教,实例计算表明了该方法的实用性。  相似文献   

Effects of continuous casting mould fluxes on reducing longitudinal and star cracks on a slab surface     

WANG Qian  WANG Yu  CHI Jinghao  XIE Bing  HE Yuming  ZHU Bing  CHEN Wenman College of Materials Science  Engineering  Chongqing University  Chongqing  P. R. Chin  Steel making Plant  Chongqing Iron & Steel Company  Chongqing  P. R. Chin 《重庆大学学报(英文版)》2004,3(1):65-68

1.IntroductionAstothecurrenttechnologyofcontinuouscastingofsteel,itisanemergencyformouldfluxestoharmonizetheconflictsbetweenheattransferandlubricationforslabcasting.Whenstructuralsteelwhosemassfractionofcarbonwcis0.09%to0.15%andhighstrengthlowalloysteel(HSLA)whosewcis0.14%to0.25%arecontinuouslycast,itisnecessarytocontroltheheatfluxfromtheslabshelltothecoppermouldnottoexceed1.7?06W/m2becauseofthebigandcoarseausteniticcrystalsintheinitialsolidifiedslabshell[1].Otherwise,longitudinalcrackstendt…  相似文献   

Using Stated-Preference Questions to Investigate Variations in Willingness to Pay for Preserving Marble Monuments: Classic Heterogeneity, Random Parameters, and Mixture Models     

Edward Morey  Kathleen Greer Rossmann 《Journal of Cultural Economics》2003,27(3-4):215-229

This paper investigates heterogeneity in the preferences/WTP (willingness to pay) to preserve marble monuments in Washington, D.C. This is done in the context of three different discrete-choice random-utility models. The main focus is to estimate a mixture model of choices over preservation programs. This model captures the best features of random-parameters models and models that assume preference parameters are deterministic functions of observable characteristics of the individual. The mixture model, and it alone, predicts that increased preservation is a bad for a significant proportion of young, non-Caucasians. That some proportion of the population might consider preservation a bad is a contingency that should be planned for in efforts to value cultural resources. Data and computer code are available athttp://www.colorado.edu/economics/morey/dataset.html.  相似文献   

有氧训练对红细胞自由基代谢和Na^＋-K^＋-ATP酶活性影响     

李敏  曹志发 《浙江体育科学》2006,28(6):88-90

探讨不同时间负荷训练大鼠红细胞自由基代谢和Na -K -ATP酶活性。结果表明急性运动时红细胞产生氧化应激,而有氧训练使红细胞自由基代谢得以改善。运动训练改善红细胞自由基代谢和Na -K -ATP酶活性和每日训练持续时间有一定的关系,在一定程度上红细胞自由基代谢水平影响着红细胞膜功能蛋白活性。  相似文献   

中国国家女子手球队运动员赛前训练的生化特点及机能评定   总被引：7，自引：0，他引：7  

魏宏文  魏宏强  裴怡然  肖卓威  高伟  杨和平 《北京体育大学学报》2007,30(4):492-494

为了解女子手球运动员赛前训练的生化特点和身体机能的变化规律.测定了19名参加2006年亚洲锦标赛赛前备战的国家女手运动员某些生化指标的变化.结果表明:1)赛前备战期国家女手运动员Rbc、Hb、Hct测定值变化幅度不大,在赛前2周达到了整个备战期的较高水平;2)赛前训练期,国家女手运动员白细胞总数在临床正常参考值范围;3)赛前训练期国家女手运动员血清CK、UREA变化幅度不大,血清CK的离散度较大;4)在赛前2周,国家女手运动员血清睾酮达到最高,血清皮质醇达到最低.结论:赛前运动员的血液携氧能力、营养状况、内分泌机能状态在赛前2周达到了较好状态;血清CK表现出较强的个体差异性.  相似文献   

对国家男排队员跳发球技术的运动学比较研究   总被引：7，自引：0，他引：7  

虞重干  张松宁  邹亮畴  余有为  杨志光  董军 《上海体育学院学报》1990,(3)

跳发球是近年来国内外男排比赛中主要的发球得分手段。本文通过对5名,中国男排队员的跳发球技术及2号位扣球技术、正面上手发球技术的影片解析,获取了跳发球技术的特征;揭示了跳发球与2号位扣球及正面上手发球在技术上的不同点,从而为跳发球训练提供一些理论依据和运动学参数。  相似文献   

激光相变硬化层预测与控制简易模型     

吴钢　 石娟宋光明  戴忠森 《上海海事大学学报》2001,22(1):12-16

根据激光扫描时工件内温度场及硬化层的分布特征，提出了简便实用的硬化层预测计算公式。并在此基础上，提出了以硬化层分布均匀性最佳为目标的激光参数优化模型。  相似文献   

运动员红细胞免疫功能初探   总被引：3，自引：0，他引：3  

廖晓  田文彦 《成都体育学院学报》1994,(2)

酵母花环法检测４５例成都体育学院运动系学生红细胞免疫粘附功能；红细胞免疫调节促进因子；抑制因子及红细胞增强中性粒细胞吞噬作用试验。同时选择年龄、性别与运动员组相同条件的四川省卫生干部管理学院４１名体检正常学员作为对照组。实验结果显示运动员红细胞Ｃ３ｂ受体花环率（ＲＣＲ）明显高于对照组（Ｐ＜０．００１），红细胞受体花环促进率（ＲＴＥＲ）高于对照组（Ｐ＜０．００５），吞噬增强率高于对照组（Ｐ＜０．０５）。  相似文献   

Hierarchically structured porous materials: synthesis strategies and applications in energy storage     

Liang Wu  Yu Li  Zhengyi Fu  Bao-Lian Su 《国家科学评论(英文版)》2020,7(11):1667

To address the growing energy demands of sustainable development, it is crucial to develop new materials that can improve the efficiency of energy storage systems. Hierarchically structured porous materials have shown their great potential for energy storage applications owing to their large accessible space, high surface area, low density, excellent accommodation capability with volume and thermal variation, variable chemical compositions and well controlled and interconnected hierarchical porosity at different length scales. Porous hierarchy benefits electron and ion transport, and mass diffusion and exchange. The electrochemical behavior of hierarchically structured porous materials varies with different pore parameters. Understanding their relationship can lead to the defined and accurate design of highly efficient hierarchically structured porous materials to enhance further their energy storage performance. In this review, we take the characteristic parameters of the hierarchical pores as the survey object to summarize the recent progress on hierarchically structured porous materials for energy storage. This is the first of this kind exclusively to survey the performance of hierarchically structured porous materials from different porous characteristics. For those who are not familiar with hierarchically structured porous materials, a series of very significant synthesis strategies of hierarchically structured porous materials are firstly and briefly reviewed. This will be beneficial for those who want to quickly obtain useful reference information about the synthesis strategies of new hierarchically structured porous materials to improve their performance in energy storage. The effect of different organizational, structural and geometric parameters of porous hierarchy on their electrochemical behavior is then deeply discussed. We outline the existing problems and development challenges of hierarchically structured porous materials that need to be addressed in renewable energy applications. We hope that this review can stimulate strong intuition into the design and application of new hierarchically structured porous materials in energy storage and other fields.  相似文献   

Enhancing creativity and innovation in engineering education     

I. Badran 《European Journal of Engineering Education》2007,32(5):573-585

With the rapid progress of modern civilization, creativity and innovation within a techno-economic perspective are becoming the major driving forces behind the sustainability of economic growth and competitive achievements. The current paper will focus on developing a clear concept of the terms creativity and innovation, and investigate their possible relation with engineering education. The parameters that could be essential for the enhancement of creativity or innovation are discussed from the perspective of the individual and the community. An engineering creativity enterprise diagram (ECED) is introduced to be reflective of the industrialization and technological level of any community as correlated to creativity and innovation. A systematic approach is designed to help developing the possible courses and activities that would enhance creativity and innovative skills and capabilities of a graduate engineer.  相似文献