HgCdTe焦平面探测器热应力有限元分析

为降低HgCdTe焦平面探测器的内热应力、提高其可靠性,在MSC Patran和MSC Nastran 中对HgCdTe焦平面探测器进行热-力耦合分析.借助MSC Patran的参数化建模方法建立焦平面探测器的有限元模型,对该模型进行热分析,将结果作为温度载荷进行静力分析,得出HgCdTe芯片热应力分布情况.通过分析5...     

考虑人体散热的轿车座舱内流场数值仿真研究

研究提高轿车热舒适性,汽车座舱空气的对流和人员体温,都会影响舒适度,有必要在开发前期,用数值方法对轿车座舱内流场进行仿真.根据雷诺平均的方法,应用RNGc-E湍流模型,为了控制舱内舒适性能,采用分区域划分网格的方法,对座舱内空气三维流场和温度场进行了数值仿真研究.引入人体模型,考虑车内人体散热对座舱内环境的影响,建立了轿车座舱舒适性研究的模型.给出了座舱内不同位置的速度分布和温度云图,分析了空调给风角度、空调给风口位置以及空调回风口位置对座舱内气流组织及温度场的影响.结果表明,采用前-中给风的给风口布置和后回风形式以及上攻角的给风口设计,均可以提高轿车座舱内乘员的热舒适性.     

纳卫星主动温控系统建模与仿真

纳卫星运行于复杂空间热环境中,各种热量干扰、轨道外热流波动和舱内热源的散热都会影响整个星体的温度系统,因此制定合理的温度控制策略尤为重要.在纳卫星动态特性平衡方程基础上建立了主动热控系统模型.分别采用常规PID控制方法与模糊控制方法,对纳卫星温度控制系统进行了仿真研究.仿真结果表明,PID控制能消除稳态误差,满足一定的控温要求,但超调大,过渡时间长;模糊控制则能实时跟踪纳卫星温度变化,较快地达到控温目标值,虽然无法消除静态误差,但其综合控制效果比PID要好.     

基于ANSYS的兆瓦级风力发电机组机舱罩分析仿真

通过有限元分析能对极限风载下机舱罩结构强度进行有效分析仿真.本文首先研究了某新型机舱罩关键部件--上机舱罩在极限风速条件下的受力分析理论模型,以及ANSYS三维有限元分析的基本步骤,并在此基础上介绍了利用ANSYS软件建立上机舱罩三维有限元模型,设定有限元分析参数,约束边界条件,施加外部载荷等具体操作方法,从而构建了一种基于ANSYS的大型兆瓦级风电机组机舱罩受极限风载时的三维有限元分析仿真方法.     

机舱内紧急人员疏散最优模型仿真分析

研究机舱内人员疏散有利于获取最佳逃生路径,保护生命安全.机舱内的空间相对封闭,在突发状况下,疏散的渠道有限,受到突发状况影响很多,无法对意外进行完全的约束建模.传统的疏散模型在小空间疏散路径寻优计算过程中,以固定约束条件描述疏散时的状况,路径选择设定了很多前提条件,应用性较差.提出利用非规则变异算法的机舱内紧急人员疏散模型.计算机舱内紧急人员疏散目标函数,并且针对所有的疏散路径进行编码,获取不同疏散方法的评价标准,并利用上述标准对人员疏散模型进行评价,针对所有的疏散路径进行选择、交叉和变异运算,建立机舱内紧急人员疏散最优模型,得到改进模型的最优解,获取机舱内紧急人员疏散的最优路径.实验结果表明,利用改进算法进行机舱内紧急人员疏散,能够获取最优疏散路径,提高疏散效率.     

磁盘机盘片的面内及弯曲热变形分析

本文分析了磁盘机盘片在一定温度分布下的热变形，得出了盘片面内热变形量以及弯曲变形挠度与温度变化之间的解议关系式，同时分析了盘片热变形形式与温度分布的关系，提出了对盘片热设计的建议。     

某民用直升机舱内噪声水平仿真分析研究

声学仿真分析是进行直升机舱内降噪设计的有效技术手段,良好的降噪设计有利于提升民用直升机的市场竞争力。结合试验数据和统计能量法分析了某民用直升机的舱内噪声源贡献度,进而采用声学边界元法分析了该型机的舱内噪声水平。研究表明,该型机舱内主要噪声源为：主减振动、发动机振动、主减空间辐射声、发动机空间辐射声和油箱舱空间辐射声,在无内饰状态下人耳敏感频率范围内的舱内场点噪声为129 dB,蒙皮、整流罩和挡板是影响舱内噪声水平的关键结构,在考虑内饰材料后,场点噪声最大可下降5 dB。该分析思路可以为直升机舱内降噪设计提供技术支持。     

机舱内部超宽带无线信道参数仿真

在机舱无线信道传输特性优化问题的研究中,将超宽带无线通信系统应用到机舱环境中,首先需要对机舱无线信道参数特性进行研究,优化信道模型参数.针对机舱环境,采用射线追踪的软件仿真方法来模拟超宽带信号在机舱内部的传播路径,计算信道模型参数.提出采用接收球的反射角误差法,通过信号传播距离、入射角度、反射角度之间的数学关系,来追踪信号传播路径.建立ARJ21机舱内部模型仿真信号传播路径,对仿真数据进行统计分析,得到信道特性参数:簇到达率、簇衰减常数、径衰减常数,以及均方根时延扩展,优化信道特性参数,可为机舱内部信号传输提供参考.     

基于格子波尔兹曼方法的机舱散热耦合分析

为指导前保险杠格栅及开口设计,研究冷却系统在特定工况下的散热性能和流场分布,建立具有详细的发动机舱几何信息的整车模型,利用格子波尔兹曼方法模拟整车在数字风洞中的热性能,得到机舱内流场和温度场以及散热器出水温度.分析结果与实验数据一致性很好,因此格子波尔兹曼方法很适合解决具有复杂几何结构的机舱散热问题.基于对标模型,针对前保险杠格栅的开口和格栅形式提出改进优化建议.经过多轮优化,散热器的散热能力提升6.94%.     

纯电动汽车热泵空调系统模糊控制策略优化

为了提高新能源汽车乘客舱的热舒适性,综合考虑汽车空调控制系统的复杂性,对纯电动汽车热泵空调系统的模糊控制策略进行优化.利用AMESim建立纯电动汽车热泵空调系统模型,采用MATLAB\Simulink建立系统直流电动机的模糊控制器模型,并将两种模型进行耦合,在不同环境工况下对车舱温度变化进行联合仿真.研究表明,传统模糊...     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.