基于C／S与B／S架构的IM软件的研究与分析

IM软件是当今以Internet网络为基础的实时通信系统,在实现上主要基于两种架构,分别是基于C／S架构和B／S架构的。基于C／S架构的IM软件主要使用了TCP或UDP协议、P2P~Socket等技术,实现起来较容易,但是用户需要自己安装客户端软件;基于B／S架构的IM软件主要应用了Ajax、ServerPush、服务器轮询等技术,实现起来比较复杂,但是用户不需要安装客户端软件,只需通过浏览器即可实现网上聊天功能。     

UHV／CVD生长SiGe／Si材料分析及应用研究

以Si2H6和GeH4为生长气源,采用UHV／CVD系统在Si（100）衬底上生长了Sil—xGex合金和Sil—xGex／Si多量子阱结构。采用X射线双晶衍射仪、扫描电子显微镜和原子力显微镜等仪器设备对样品的组份、界面和表面形貌等晶体质量进行了研究。SiGe合金中Si和Ge摩尔分数的比值随着Si2H6和GeH4流量比的增加按比例线性增加,比例因子为2．57。生长的Si0．88Ge0．12合金样品的界面清晰,表面平整,平均粗糙度仅为0．4nm,位错密度低于104／cm2。六周期Si0．88Ge0．12／Si多量子阱的X射线双晶衍射摇摆曲线中存在多级卫星峰和Pendellosung条纹。这些结果表明SiGe合金和SiGe／Si多量子阱均具有很好的晶体质量。     

Field dependence/independence cognitive style and problem posing: an investigation with sixth grade students

Field dependence/independence cognitive style was found to relate to general academic achievement and specific areas of mathematics; in the majority of studies, field-independent students were found to be superior to field-dependent students. The present study investigated the relationship between field dependence/independence cognitive style and problem-posing ability among sixth grade students. The 94 students’ sample was clustered into three groups, according to the cognitive-style field dependence/independence (field dependents, field mixed and field independents). The results suggest that field-independent participants outperformed field-mixed and field-dependent ones in both problem-posing ability and the complexity of the problems posed. It was also found that the content of the task influenced the differences between the three groups of students as regards the ability in problem posing and the complexity of the problems posed; while in the first (informal context), second and fourth task differences were found between the groups, in the third task (formal context), no differences were evident. The results are interpreted in consideration to the relevant literature findings. Some educational implications are discussed and directions for future research are drawn.     

Extension for organic agriculture: a comparative study between Baden-Württemberg,Germany and Crete,Greece

Purpose: The aim of this paper is to compare the extension services offered in the field of organic agriculture (OA) in Baden-Württemberg (BW), Germany and Crete, Greece.

Design/methodology approach: 16 in-depth interviews, 10 in BW and 6 in Crete, were carried out with representatives of OA extension providers; interviews were qualitatively analyzed and overall results compared between the two areas.

Findings: The structure along with extensionists' capacities and methods employed are rich, appropriate, and well functioning in BW. On the contrary, poor structure, lack of networking and facilitation in Crete jeopardizes extension performance and impact. Practical implications: Contrary to BW, the situation in Grete does not allow for much optimism concerning the successful development of OA and the implementation of European Innovation Partnerships.

Theoretical implications: Further elaboration of the characteristics of extension/advisory services and their interlinkages, including the role of the state in facilitating pluralistic services, is needed.

Originality/value: The paper demonstrates the importance of the structure of extension services and the central facilitation role of the state; furthermore, the interdependency of structure, capacity and the methods employed is demonstrated which, in turn, influences extension performance and impact especially networking and facilitation for social learning and innovation co-creation.     

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

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.     

J/ψ和ψ（2S）衰变中η和η′混合的研究

基于不同实验组给出的J/ψ,ψ（2S）→VP的分支比,我们对赝标量介子η和η′混合的可能性进行了研究.发现如果只计及夸克组元,拟合给出的混合角分别为（-14.04±2.37）°和（-11.99±10.46）°;而如果η和η′同时含有胶子组分,则η可能只有轻的夸克组成,η′中的胶子组分可能为Zη2′=0.30±0.24.     

基于.NET平台的开放式实验室管理系统

采用．net组件技术、B／S体系结构和SQL Server数据库设计了开放式实验室管理系统。系统分管理员、教师、学生三个子平台,并对其关键的功能模块进行了深入的分析研究。     

MATLAB/SIMULINK在“电力电子变流技术”课程教学中的应用

针对＂电力电子变流技术＂课程中电路种类多,学生难以理解等问题,提出在该课程教学中利用MATLAB工具进行交互式学习的模式,并以阻感性负载单桥桥式整流电路为例,详细介绍了模型的建立和仿真。结果表明,学生通过MATLAB仿真工具可以全面直观深入的理解＂电力电子变流技术＂课程的学习内容,为该课程的教与学提供了一种新的思路和模式。     

基于遗传算法的高校排课系统设计与实现

随着高等教育的发展,学生人数不断增加,而教室资源和教师资源有可能相对有限,排课就成为教学管理中十分重要且又相当繁重的工作之一。文章根据高校排课特点,在对排课系统及遗传算法基本理论分析的基础上,使用基本遗传算法SGA,设计并开发出了一个基于B/S模式的排课系统CAS,以满足高校教学管理工作不断发展的需要。     

基于Web的网络教学辅助系统的设计与实现

新知识不断膨胀的信息时代,需要人们必须找到一种新的分析、处理和运用知识信息的教学手段和学习方法。从实际教学角度出发,分析了网络教学的发展前景,设计并实现了基于Web的网络教学辅助系统。