Random vibration analysis of switching apparatus based on Monte Carlo method

The performance in vibration environment of switching apparatus containing mechanical contact is an important element when judging the apparatus’s reliability. A piecewise linear two-degrees-of-freedom mathematical model considering contact loss was built in this work, and the vibration performance of the model under random external Gaussian white noise excitation was investigated by using Monte Carlo simulation in Matlab/Simulink. Simulation showed that the spectral content and statistical characters of the contact force coincided strongly with reality. The random vibration character of the contact system was solved using time (numerical) domain simulation in this paper. Conclusions reached here are of great importance for reliability design of switching apparatus.     

水稻免耕栽培生理基础——Ⅱ.免耕水稻的光合特性

威优64、陆青早1号作为试验材料,免耕能提高功能叶的光合速率、生育前期功能叶的呼吸强度、绿叶面积、叶绿素和可溶性蛋白含量,并延缓它们在生育后期的下降速率,降低后期功能叶的呼吸速率。主分量分析说明,在研究光合作用时,光合强度、叶绿素、可溶性蛋白质、叶片含氮量,可以任意选择一个作为光合特性指际。粒/叶比说明,免耕对源的改善较对库的改善较好些。     

浅谈多媒体教学在大学英语教改中之利弊

文章结合西方现代外语教学理念与大学英语教改指导思想,阐述了多媒体辅助教学在大学英语教改中之利弊.     

应用型本科CAD/CAM课程教学改革之初探

围绕应用型本科的培养目标和机械设计制造及自动化专业CAD/CAM课程教学的特点,从教学内容、教学方法、教学模式、考试方法及提高教师自身素质等方面的教学改革进行有益的尝试和探讨.     

思维模式差异与英文写作

东西方思维模式存在差异。西方人遵循单向式思维模式,而东方人则遵循多向式思维模式。表现在写作上,西方人倾向借助线性发展模式,而东方人则常使用螺旋型模式展开语段。思维模式的差异导致了许多中国学生在英文写作中缺乏连贯性和逻辑性。为改变这一现状,教师可引导学生运用写作图式,尝试将"支架"理论引入写作教学,加强写作连贯性和逻辑性的训练。     

“快乐足球”教学模式探讨

兴趣是学生获得知识、开扩眼界、丰富心理活动的重要动力,“快乐的课堂气氛是激发学生学习兴趣,提高学习积极性的前提”,在足球教学中,要运用先进的教学方法和手段,充分提高学生的学习兴趣,让学生形成快乐的情感体验。     

Paired peer learning through engineering education outreach

ABSTRACT

Undergraduate education incorporating active learning and vicarious experience through education outreach presents a critical opportunity to influence future engineering teaching and practice capabilities. Engineering education outreach activities have been shown to have multiple benefits; increasing interest and engagement with science and engineering for school children, providing teachers with expert contributions to engineering subject knowledge, and developing professional generic skills for engineers such as communication and teamwork. This pilot intervention paired 10 pre-service teachers and 11 student engineers to enact engineering outreach in primary schools, reaching 269 children. A longitudinal mixed methods design was employed to measure change in attitudes and Education Outreach Self-Efficacy in student engineers; alongside attitudes, Teaching Engineering Self-Efficacy and Engineering Subject Knowledge Confidence in pre-service teachers. Highly significant improvements were noted in the pre-service teachers’ confidence and self-efficacy, while both the teachers and engineers qualitatively described benefits arising from the paired peer mentor model.     

Hydrogenation properties of mechanically milled Mg2Nio.8Cr0.2-CoO/Al2O3 composites

Mg2Ni0.8Cr0.2-x wt.% CoO/Al2O3 (x=0.5, 1, 2 and 3) composites were prepared by mechanically milling sintered Mg2Ni0.8Cr0.2 alloy and CoO/Al2O3 compound for 45 h. The addition of CoO/Al2O3 compound resulted in the good kinetics properties of hydriding/dehydriding reaction of the composites. The composite with 1.0 wt.% CoO/Al2O3 catalyst could reach the maximum hydrogen absorption capacity (2.9 wt.%) within 5 min at 393 K under H2 pressure of 4 MPa, and can desorb rapidly at 493 K. The decomposition and synthesis of hydrogen molecule on Mg2Ni0.8Cr0.2 alloy surface was promoted by addition of CoO/Al2O3 catalyst. In addition, the formation of metallic Ni particles, strain and defects during the ball milling process also resulted in the improved hydrogenation performance of Mg2Ni-based alloys.     

从汉德民族社交语用看东西方思维方式的差异

汉民族和德意志民族由于不同的文化传统、不同的哲学宗教以及不同的社会发展经历．在思维方式上存在着较大的差异。这种差异从某种意义上来说也代表了东西方文化和思维方式的差异。从两个民族的社交语用上探讨和研究这种差异，对提高跨文化交际能力，避免因不同的文化背景和相异的思维方式而产生的不必要误解具有较大的现实意义。     

结合专业特色应用现代教育技术服务于中小学教学

现代教育技术的应用,深刻影响高中小学各科教学.传统的教学模式必须与现代教育技术进行整合,才能适应新课程教学改革的需要.充分发挥教育技术专业人才的主导作用,担当教育技术现代化的排头兵.