Random vibration analysis of switching apparatus based on Monte Carlo method     

ZHAI Guo-fu CHEN Yang-hua REN Wan-bin 《浙江大学学报(A卷英文版)》2007,8(3):422-425

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.  相似文献   

水稻免耕栽培生理基础——Ⅱ.免耕水稻的光合特性     

李小林  王永锐 《中山大学学报论丛》1989,(5)

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。  相似文献   

英汉互译中的跨文化交流意识     

樊葳葳  周德慧 《华中科技大学学报(社会科学版)》2001,15(3):120-123

翻译是跨文化交流过程中时常涉及的一个中介环节。本文在英汉互译中 ,引入跨文化交流意识 ,旨在立足于传统翻译学对翻译的认识上 ,从跨文化角度深化翻译的内涵 ,并通过分析翻译实践与某些文化因素之间的关联 ,突现出翻译中易出现的文化方面的问题 ,进一步探讨了翻译中应持的文化态度以及翻译者应具备的文化素质  相似文献   

应用型本科CAD/CAM课程教学改革之初探     

袁新芳  刘极峰 《职教通讯(江苏技术师范学院学报)》2004,10(2)

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.  相似文献   

Paired peer learning through engineering education outreach     

Laura Fogg-Rogers  Fay Lewis  Juliet Edmonds 《European Journal of Engineering Education》2017,42(1):75-90

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.  相似文献   

谈节目主持人栏目的固定性与受众的相对稳定性     

徐畅 《青海师范大学学报(哲学社会科学版)》2006,(1):110-113

节目主持人以真实自我面对受众,其真实的声音、形象、个性特征对主持人节目的成功起着重要作用。主持人个性化的主持风格为受众所认同就意味着该主持人及其栏目有了一定的受众,其主持人的固定性关系到栏目的发展和受众群的相对稳定性。  相似文献   

WinSock控件在网络编程中的应用     

孟冬梅  王维治 《天津职业院校联合学报》2002,4(4):88-91

WinSock控件是Windows应用程序和TCP/IP之间的一个接口控件。借助于WinSock控件可以有效地对网络进行编程。在论述了WinSock控件的原理及其特点的同时,重点给出了在VB下开发基于WinSock控件的网络通信程序及邮件处理程序的方法。  相似文献   

La Parte Chusca of a Pedagogical Here and Now: Oaxacan Teachers’ Heteroglossic Joking About State Repression and Educational Reform     

Stephen T. Sadlier 《Journal of Latinos & Education》2016,15(4):320-332

Faced with repression and reform, humor has become tactical for public school teachers in Oaxaca, Mexico, engaged in a decades-old movement that after 2006 involved intensified street- and school-based pedagogies. This piece explores how humor adds to a political project via mocking names, images, and dictates of elite leaders to bring a here and now to what is taken as inaccessible in the teachers’ political lives. Humor forms part of an (e)sc(h)atology in which critical practices are part eschatological, a call for definite transformation, and part scatological, embodied vulgarity. La parte chusca (the funny part), its (e)sc(h)atological contribution, angles toward critical literacies in Oaxaca and beyond.  相似文献   

Cu-ZnO/Al2O3催化仲丁醇制备甲乙酮     

林武滔  李增富  邱凡 《三明学院学报》2007,24(4):420-424

用Cu-ZnO/Al2O3催化仲丁醇制备甲乙酮。研究了催化剂的焙烧温度和焙烧时间、仲丁醇脱氢反应的温度和压力以及仲丁醇的流量对仲丁醇转化率和甲乙酮选择性的影响。结果表明,催化剂的焙烧温度为300-400℃,焙烧时间为6h,脱氢反应的温度为300℃,压力为0.2Mpa,仲丁醇的流量为140mL/h时,仲丁醇的转化率和甲乙酮的选择性较好。  相似文献   

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

WANG Xiu-li  TU Jiang-ping  CHEN Chang-pin  ZHANG Xiao-bin  ZHAO Xin-bing 《Journal of Zhejiang University. Science. B》2005,(3)

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.  相似文献