Rate-equation-based VCSEL thermal model and simulation

INTRODUCTION Vertical-Cavity Surface-Emitting Lasers (VCSELs) are a new generation of semiconductor lasers that differ considerably from the conventional edge-emitting lasers. In recent years, the characteris- tics of VCSELs have improved enormously (Badilita et al., 2004). Today’s VCSELs have low-threshold current densities and high output power. Moreover, their circular output beam profiles and the suitability to be integrated into 2D arrays make them most promising candidates …     

分布式CAD环境中基于操作语义的实时协同设计

提出了一种应用于分布式CAD环境中的基于操作语义的协同设计模型. 主要目的是为了减少数据转换的耗时量以及降低对网络带宽的需求, 从而改善协作能力, 提高实时同步的效果. 首先回顾了实时协同设计的发展现状, 讨论了3种实时协同设计模型. 其次, 给出了操作语义的定义, 并提出了一个操作语义模型框架. 操作语义包含原始设计数据和实际操作过程, 表达CAD系统中的设计者意图和操作活动. 最后, 根据操作语义模型, 定义了CAD操作原语, 该原语可以从CAD操作中提取也可以映射成CAD操作命令; 给出了一种基于该模型的分布CAD协同体系结构, 并通过一个实例加以验证.     

基于BIM的结构钢筋与机电系统翻模研究——以福州市规划院产业楼为例

基于建筑信息模型（Building Information Modeling, BIM)）概念,以福州市规划设计研究院新建大楼为实际案例,应用Autodesk Revit软件将原有CAD图纸进行BIM结构钢筋和机电模型建置,并提出BIM技术虚拟仿真过程中发现的问题。研究结果表明:（１）BIM技术可实际解决工程常常出现钢筋复杂节点、机电管道碰撞的问题;（２）机电系统进行Revit翻模时,不能按原CAD路径绘制,族库不全需建族完善。该研究成果可为后期施工决策提供技术支持,并有助于相关行业人士学习与借鉴。     

Predicting introductory programming performance: A multi-institutional multivariate study

A model for predicting student performance on introductory programming modules is presented. The model uses attributes identified in a study carried out at four third-level institutions in the Republic of Ireland. Four instruments were used to collect the data and over 25 attributes were examined. A data reduction technique was applied and a logistic regression model using 10-fold stratified cross validation was developed. The model used three attributes: Leaving Certificate Mathematics result (final mathematics examination at second level), number of hours playing computer games while taking the module and programming self-esteem. Prediction success was significant with 80% of students correctly classified. The model also works well on a per-institution level. A discussion on the implications of the model is provided and future work is outlined.     

用VBNET开发轴类零件的CAD系统

探讨了轴类零件CAD系统的开发过程,包括数学模型的建立,数据的处理及CAD系统框架 最后通过一个实例验证了系统的正确性     

复杂空间认知研究中的虚拟现实技术应用

虚拟现实技术可以较为理想地表现建筑与城市空间,然而其作用不仅仅在于演示建筑与城市规划设计的成果,还可以在建筑学的空间研究中发挥更大的作用。在为同济大学建筑与城市规划学院建立了一套较大规模的虚拟现实系统以后,在此将介绍在复杂空间认知研究中虚拟现实技术的一些实际应用,并从研究应用中提出以虚拟现实系统建立适合建筑学研究的"纯粹空间"的概念。     

Automatic recognition of intersecting features of freeform sheet metal parts

This paper presents an approach for recognizing both isolated and intersecting geometric features of freeform surface models of parts, for the purpose of automating the process planning of sheet metal forming. The developed methodology has three major steps： subdivision of B-spline surfaces, detection of protrusions and depressions, and recognition of geometric features for sheet metal forming domain. The input geometry data format of the part is based on an IGES CAD surface model represented in the form of trimmed B-spline surfaces. Each surface is classified or subdivided into different curvature regions with the aid of curvature property surfaces obtained by using symbolic computation of B-spline surfaces. Those regions satisfying a particular geometry and topology relation are recognized as protrusion and depression （DP） shapes. The DP shapes are then classified into different geometric features using a rule-based approach. A verified feasibility study of the developed method is also presented.     

基于VBA的AutoCAD表面粗糙度标注二次开发

针对使用AutoCAD绘制机械图样时,表面粗糙度符号不能自动标注的问题,在Auto CAD2008中利用VBA二次开发环境,对AutoCAD2008平台上表面粗糙度标注进行了开发,创建了表面粗糙度的模块和属性。用户只需在标注系统界面上选择各项参数就能完成表面粗糙度的标注,其使用简便且界面友好。     

Computer Aided Design in Industrial Design Education

In general, Industrial Design BA courses have been slow to formulate a coherent strategy for the inclusion, implementation and integration of computers into their teaching. CAD hardware and software has appeared in many institutions as a result of the enthusiasm of one or two individuals who have used a particular CAD system themselves or been bowled over by an impressive demonstration. The possession of the equipment then to a large extent determines what kind of use can be made of it, and this is also subject to the vagaries of staff time and expertise, both of which are often in short supply. Basic questions, such as ‘What is the purpose of CAD education in this course?’ or ‘What kind of computing do the students really need?’ are often by-passed until it is too late. Over the last three years at Sheffield Hallam University a conscious attempt has been made to evolve an approach which begins with questions such as these and results in a coherent teaching and learning strategy for our students.     

Virtual realities in environmental education: the project LAKE

This article proposes the use of virtual realities (VR) in environmental education. It also presents the first results of an application to the phenomenon of eutrophication in lakes. Although our virtual environments are not immersive, they give the opportunity to students and educators to develop their own worlds and understand the population dynamics in a lake. The learning environment can be manipulated and controlled in a powerful way, enhancing students experiences leading to knowledge construction, and sensitizing students to current environmental problems. Our pedagogical approach is to build a theoretical model for virtual learning environments, expanding constructivism and combining it with experiential learning. Our operational and practical approach is to exploit the characteristics of desktop VR systems in virtual learning environments     

约简算法在商业银行CRM中的应用研究

针对银行CRM中的数据冗余大、数据挖掘效率低的问题,将基于属性约简的数据预处理方法应用在银行CRM中.使用决策表属性重要度属性约简算法简化客户贡献度决策表,实现决策表条件属性的归约.通过该算法在某商业银行CRM数据预处理过程中的实际应用,证实约简算法应用在银行CRM系统是有效可行的.     

Comparison of Attribute Reduction Methods for Coronary Heart Disease Data by Decision Tree Classification

Attribute reduction is necessary in decision making system. Selecting right attribute reduction method is more important. This paper studies the reduction effects of principal components analysis （PCA） and system reconstruction analysis , SRA） on coronary heart disease data. The data set contains 1723 records, and 71 attributes in each record. PCA and SRA are used to reduce attributes number （less than 71 ） in the data set. And then decision tree algorithms. C4.5, classification and regression tree （ CART）, and chi-square automatic interaction detector （ CHAID ）, are adopted to analyze the raw data and attribute reduced data. The parameters of decision tree algorithms, including internal node number, maximum tree depth, leaves number, and correction rate are analyzed. The result indicates that. PCA and SRA data can complete attribute reduction work. and the decision-making rate on the reduced data is quicker than that on the raw data： the reduction effect of PCA is better than that of SRA. while the attribute assertion of SRA is better than that of PCA. PCA and SRA methods exhibit good performance in selecting and reducing attributes.     

基于Geomagic Studio的细分造型技术研究

运用逆向工程专用软件可以使点云生成三角网格面,它是原始模型的线性逼近,光滑度较低。为了改善曲面的光滑度,经过对细分造型技术的研究,在分析Loop细分模式和细分模式的基础上,揭示GeomagicStudio软件中细分造型功能的原理．建立在三角网格面模型基础上的细分曲面造型技术可以改善曲面光滑度。     

Who succeeds in STEM studies? An analysis of Binghamton University undergraduate students

Using student level data, the characteristics of STEM and Non-STEM students are examined for attributes associated with academic success. We use fixed effects models to analyze the variables’ role in attaining graduation and college GPA and find preparation and ability, as evidenced by Advanced Placement course work, mathematical ability, gender, ethnicity, high school GPA and college experience are all statistically significant indicators of success. These attributes may confer a comparative advantage to STEM students. The engineers have statistically significant differing response elasticities than the non-engineers, and show evidence of persistence that may arise from learning-by-doing. A successful engineering STEM major at Binghamton has good mathematics preparation, and disproportionately is of Asian ethnicity. Women are few in numbers as engineers. Other STEM fields see less emphasis on mathematics preparation, but more emphasis on the presence of AP course work. Women have the same presence in these other STEM fields as in the whole university.     

Using multi-class queuing network to solve performance models of e-business sites

Due to e-business's variety of customers with different navigational patterns and demands, multi-class queuing network is a natural performance model for it. The open multi-class queuing network(QN) models are based on the assumption that no service center is saturated as a result of the combined loads of all the classes. Several formulas are used to calculate performance measures, including throughput, residence time, queue length, response time and the average number of requests. The solution technique of closed multi-class QN models is an approximate mean value analysis algorithm (MVA) based on three key equations, because the exact algorithm needs huge time and space requirement. As mixed multi-class QN models, include some open and some closed classes, the open classes should be eliminated to create a closed multi-class QN so that the closed model algorithm can be applied. Some corresponding examples are given to show how to apply the algorithms mentioned in this article. These examples indicate that multi-class QN is a reasonably accurate model of e-business and can be solved efficiently.     

CAD与GIS数据的可视化转换方法研究

对CAD和GIS数据模型进行分析后,论述了如何高效构造可视化的转换模型。可视化转换模型可以在转换结果的准确性和工作效率间找到平衡点,是一种方便、快捷、高效的解决方案。     

基于三维打印原理的计算机辅助模型制作

分析了三维打印的工作原理,并基于工作原理研究了计算机辅助模型制作的模式。用等距或不等距的截面与计算机三维模型求截交线,并对截交线进行处理,将截交线打印绘制于具体板材上,然后对板材进行剪切,最后依次将材料一层层堆积而成实物模型。以具体实例详细介绍制作流程,并分析了其中的注意事项。     

带冠涡轮盘电火花加工专用CAD/CAM软件开发

In this paper,a special-purpose CAD/CAM software package,BliskCad/Cam,based on a commercial CAD/CAM software Unigraphics is developed to reduce difficulties in CNC-EDM of the shrouded turbine blisks.The software package con- sists of five modules such as electrode design,path searching,and machining simulation module.Functions of BliskCad/Cam include parametrical reconstruction of 3-D model of the blisk,intelligent design of complex shaped electrode,automatic gener- ation of NC codes,search of interference-free tool path for multi-axis NC-EDM and machining simulation,etc.Experimental verification is conducted by using BliskCad/Cam and the results show that it satisfies the requirements,and can realize pre- cision machining and reduce accessorial time remarkably.     

虚拟现实技术教学效用模型建构与实效验证

虚拟现实(Virtual Reality,VR)技术因在交互性、沉浸性和认知性方面具有独特优势而被认为是一种能够促进教育教学发展的新型手段,但是,VR技术在教学中发挥效用的内在机制还有待深入考证。教学效用是衡量技术能否发挥教学效果及其程度的指标,具体包括学习参与、教学效率和教学效果三个维度。结合VR的技术优势和教学效用维度、经由理论演绎建构的基于VR技术的教学效用模型(VR-E3Model),聚焦于研究VR的交互过程、沉浸过程和认知过程三方面效用。其中,影响交互性效用的因素包括软件因素、硬件因素、感知有用性、感知易用性、行为意向、学习者特征等;影响沉浸性效用的因素包括感知、交互感、沉浸感、临场感等;影响认知性效用的因素包括情绪信息、知识建构、认知发展等。经过实证研究检验表明,该模型具有较好的理论解释力;VR技术产生教学效用的首因要素是教师的教学行为意向;VR技术因软硬件的差异,会为使用者带来不同的交互体验;学校在配置VR设备时应从教学需求和成本投入两个维度进行综合考量。     

基于粗糙集理论的工控界面多智能体协作模式研究

1 Introduction An agent is an autonomous entity that runs in a dy-namic environment . Generally, it describes mentalstates such as knowledge , belief , promise , ability,etc. A multi-agent system ( MAS) consists of severalcomputational agents .It ai ms to transformlarge andcomplicated tasks to small ones that can communicateand cooperate with each other[1-3].Therefore ,cooper-ationis essential in MAS. The rough set theory (RST) was proposed by thePolish Mathematician Pawlak in 1982 .It w…