Operating systems     

M. Suresh Babu 《Resonance》2002,7(4):60-66

The objectives and stages of operating systems introduced in Part 1 are continued here. Four major components —process management, input-output (I/O) device management, memory management, file management and protection are discussed.  相似文献   

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   

Should Science be Taught in Early Childhood?     

Haim?EshachEmail author  Michael?N.?Fried 《Journal of Science Education and Technology》2005,14(3):315-336

This essay considers the question of why we should teach science to K-2. After initial consideration of two traditional reasons for studying science, six assertions supporting the idea that even small children should be exposed to science are given. These are, in order: (1) Children naturally enjoy observing and thinking about nature. (2) Exposing students to science develops positive attitudes towards science. (3) Early exposure to scientific phenomena leads to better understanding of the scientific concepts studied later in a formal way. (4) The use of scientifically informed language at an early age influences the eventual development of scientific concepts. (5) Children can understand scientific concepts and reason scientifically. (6) Science is an efficient means for developing scientific thinking. Concrete illustrations of some of the ideas discussed in this essay, particularly, how language and prior knowledge may influence the development of scientific concepts, are then provided. The essay concludes by emphasizing that there is a window of opportunity that educators should exploit by presenting science as part of the curriculum in both kindergarten and the first years of primary school.  相似文献   

虫媒登革病毒的研究——Ⅱ.登革病毒非结构蛋白NS1的纯化、鉴定及其在临床检测应用     

许琳  郭辉玉 《中山大学学报论丛》1995,(2)

本文从纯化Den2 NS1,Mab入手,自制了Mab亲和层析系统,从感染Den2的细胞膜中,分离提取了天然的Den 2 NS1双体,比较其NGC株与我国地方株(H-87)NS1的理化性质及组成,并对某些重要的生物学性质进行了综合性研究。同时,利用上述研究结果建立了检测DF病人血清特异NS1抗体的新方法,探索其协助临床诊断及研究的可能性。  相似文献   

J2EE平台在行政审批服务系统中的应用     

韦鹏程  杨德刚  杨华千 《重庆第二师范学院学报》2006,19(6):46-49

本文分析了电子政务对国民经济所起的重大作用,简要介绍了当前流行的J2EE架构的分布式对象结构特点。设计了一个J2EE架构下的行政审批服务系统,它由客户层、中间层和企业信息系统层等三个层次组成。同时,对系统的设计方法、软件结构及实现技术进行了探讨。  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   

Thermodynamic Analysis and Comparison on Low Temperature CO_2-NH_3 Cascade Refrigeration Cycle     

查世彤  马一太  申江  李敏霞 《天津大学学报(英文版)》2003,9(3)

Intheapplicationsofindustrialandcommercialrefrig erationsystem ,iftherequiredrefrigerationtemperatureisverylow ,theconventionalvaporcompressionsystemisdiffi culttomeettherequirementbecausewhenthedifferencebe tweentheevaporatingtemperatureandthecondensingtemper atureissohighthatitishardtofindarefrigeranttomeettheneedsasthecondensingpressureisnottoohighandtheevap oratingpressureisnottoolow .Whentherefrigeratingtemper atureisverylow ,thecascaderefrigerationcycleissuitabletobeused .Itcannotonlysat…  相似文献   

武清地热热储数值模拟     

李新国  赵军 《天津大学学报(英文版)》2001,7(3):197-201

采用 AU TOU GH2热储计算软件对天津市武清县地热热储进行数值模拟计算 ,分析热储在不同开发利用条件下的特征 .主要针对无回灌和有回灌两种生产情况 ,分析地热热储的温度、压力随时间和距离的变化 ,还分析随地热水的生产 ,地热热储的生产能力、水位和压力的变化以及回灌对生产井的冷却效应  相似文献