组合式加载方法测试树脂基复合材料压缩性能的探究

纤维增强树脂基复合材料层压板的压缩强度和压缩模量是复合材料结构设计、制造和使用维护的基本力学性能参数,为新材料研发、质量控制和结构设计提供重要依据。而不同压缩性能测试方法对其最终性能指标有重要的影响,甚至得出截然不同的结果。针对以上问题,通过对现有不同复合材料压缩性能测试方法的系统分析与讨论,结合相关测试经验,通过改进ASTM D 6641和GB/T 5258中组合式加载（CLC）测试夹具,优化了CLC加载测试复合材料的压缩性能的方法,提高了复合材料压缩性能测试方法的准确性、有效性和操作简便性,对纤维增强树脂基复合材料的开发与结构设计等具有重要的现实意义。     

碳纤维复合材料的超声反射波频域定征分析

对碳纤维复合材料的孔隙率进行超声测试法研究,发现材料前后表面超声回波均值频率偏移量与材料内部孔隙率,与超声信号衰减之间存在着特定关系.提出前后表面回波均值频率偏移特性为基础的超声无损表征方法,通过最小二乘法算法对材料内部孔隙率和超声衰减进行了定量分析,实验结果证明了该方法的实用性.     

微结构参数对多孔硅层热绝缘性能的影响

研究了多孔硅层厚度,孔隙率以及多孔硅中微晶粒尺寸三个微结构参数对其热绝缘性的影响机制.实验选用p ,p-两种掺杂浓度的硅片基底,采用电化学腐蚀法,通过改变腐蚀时间和腐蚀电流密度获得不同微结构参数的多孔硅层.分别采用显微拉曼光谱法及测量显微镜聚焦法测量了样品的热导率和厚度.研究发现,多孔硅层厚度影响热量传输路径,而孔隙率和微晶粒尺寸通过降低热导率从而使多孔硅的绝热性增强.     

基于Abaqus的光学胶动态力学行为分析

黏胶的动态力学性能对终端产品可靠性的影响越来越重要.基于Abaqus的超弹性和黏弹性的本构模型定义光学胶的动态力学参数,用Abaqus/Explicit对静态压缩和落球试验进行仿真分析,通过与实际试验结果的对比验证仿真分析结果.结果表明,在准静态到高应变率的范围内,采用超弹性和黏弹性的本构模型可以准确描述光学胶的动态力学行为.     

碳化硅增强钛合金基复合材料热残余应力的有限元分析

为探寻热解碳层对涂碳SiC纤维增强Ti-15-3钛合金基复合材料（C-SiC/Ti-15-3）中热残余应力的影响,基于复合材料细观力学方法,建立在不同热解碳层厚度时C-SiC/Ti-15-3复合材料的有限元单胞模型,模拟复合材料中热残余应力的分布.研究发现,在SiC纤维表面增加碳涂层能明显降低复合材料中的热残余应力,SiC表面的热解碳层厚度对复合材料中的热残余应力有很大影响;随着热解碳层厚度的增加,最大von Mises等效应力和径向应力呈现先减小后增大的趋势.     

压电纤维复合材料层合壳的非线性动力学研究

本文对横向激励作用下的1-3型压电纤维复合材料层合壳进行了非线性动力学分析,并研究了压电特性对结构振动响应的影响.首先建立了压电纤维复合材料层合壳的非线性动力学方程,并且在已知的几何结构和材料特性基础上考虑了电场属性.然后根据位移边界条件,选择合适的振型函数,通过Galerkin方法将运动控制方程转化成两自由度的非线性常微分方程.通过数值模拟方法分析了横向激励和压电系数对压电纤维复合材料层合壳非线性振动特性的影响.通过波形图、三维相图、庞加莱图和分叉图等来研究壳体不同类型的周期和混沌运动.结果表明,外激励作用下结构存在复杂的非线性振动响应,同时压电参数对层合壳结构振动响应具有很强的调节作用.     

舰用复合材料夹层板力学特性试验研究

作为一种新型的桅杆形式,封闭式复合材料桅杆有诸多优点和广泛的应用前景.对雷达罩部分 的复合材料结构局部力学特性的研究有现实意义.从试验角度出发,结合数值模拟技术,以单跨静力加载 方式和悬臂加载方式,得到不同载荷下复合材料夹层板的应力和变形分布规律,揭示局部结构破坏的主要 原因.试验表明:夹层板结构的胶层部分对整体的结构性能有一定影响;复合材料夹层结构在蒙皮内应力值达到强度极限之前即发生破坏,说明对于夹层板结构,层间剥离是导致试件破坏的主要原因.     

周期复合材料结构高阶多尺度方法的数值精度提高策略

高阶多尺度方法在计算数学、计算力学和计算材料学等领域得到了广泛的应用,为了进一步挖掘高阶多尺度方法的计算潜力,本文结合单胞边界条件优化选择和边界层构造,提出了一种高阶多尺度方法的数值精度提高策略,并给出了施加数值精度提高策略的高阶多尺度方法的误差分析.然后,建立了周期复合材料结构弹性力学问题具有数值精度提高策略的新的多尺度数值算法.最后,通过对周期复合材料结构弹性力学问题的模拟,验证了所提出数值精度提高策略的有效性和最优的数值精度.     

固化冷却过程中复合材料参数对其应变的影响

为有效降低某复合材料固化冷却过程中的应变水平,以某圆柱形复合材料为例,利用有限元分析软件MSC Nastran,研究固化冷却过程中复合材料参数对其应变的影响.计算得到复合材料最大von Mises应变值和分布位置,分析弹性模量、泊松比、线膨胀系数、密度等参数对其应变的影响.     

金属缠绕垫片结构参数对压缩-回弹性能的影响

为分析金属缠绕垫片结构参数对螺栓法兰连接系统密封失效的影响规律,以柔性石墨-不锈钢金属缠绕垫片为研究对象,采用试验与数值模拟相结合的方法研究垫片的压缩-回弹性能,并以垫片外缘最小压应力为指标分析螺栓法兰连接系统的密封性能,考核垫片结构参数对垫片外缘最小压应力和密封性能的影响.结果 表明:试验与有限元数值模拟得到的柔性石墨-不锈钢金属缠绕垫片的非线性压缩-回弹曲线吻合很好;与工程常用的柔性石墨-不锈钢金属缠绕垫片结构参数相比,适当减小金属带宽度、石墨带宽度、缠绕层数及金属带角度可以在不同程度上提高螺栓法兰连接系统的密封性能.     

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QTE的蒙古文显示机制研究与实现

蒙古语言是中国蒙古族使用的通用语言,由于蒙古文区别于其他文字的书写方式和其自身变形机制等特点,在很多通用的文字处理引擎中都不被支持。在嵌入式产品开发与应用领域中Linux加QTE已经成为流行方式。该文给出了一种在QTE环境上实现基于标准Unicode的蒙古文点阵显示和变形算法, 并自定义了支持蒙古文的QTE组件,扩展了QTE功能,为在Linux加QTE方式的嵌入式体系结构中处理蒙古文提供了一种解决方法。     

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。