复合材料磁悬浮列车车体结构数值模拟(Ⅱ)——车体结构性能数值模拟试验

以参数化磁悬浮列车车体有限元模型为基础，在各种载荷和边界条件下开展数值模拟试验，研究各种运营环境中车体结构的静力学和动力学性能。在Siemens NX中完成车体在各种典型载荷工况下的结构静力学和动力学性能模拟试验，包括车体结构载荷变形、车体主要连接部件结构力学性能、车体频率及振型、车体结构线性屈曲性能，以及车体动力响应性能等。数值模拟结果认为给定的复合材料磁悬浮列车车体设计可行，同时验证参数化车体有限元模型的有效性。     

摇摆防屈曲支撑钢框架抗震性能分析

基于防屈曲支撑钢框架（BRBSF）和摇摆防屈曲支撑钢框架（RBRBSF）拟静力试验，建立BRBSF和RBRBSF的有限元模型，利用OpenSees有限元软件对试验框架中采用的梁端削弱截面（RBS）进行分析，研究RBS对BRBSF和RBRBSF性能影响，并基于有限元模型进一步分析BRB参数对RBRBSF的影响.研究结果表明，梁端设置RBS可减小BRBSF梁柱节点弯矩，实现塑性铰外移，但对RBRBSF梁柱节点弯矩影响较小，BRB参数的改变对RBRBSF屈服荷载和承载能力有一定影响，但对框架柱轴力影响较小.     

基于有限元模型的建筑混凝土柱屈曲承载力计算

为了解决传统混凝土承载力算法存在峰值负荷计算值误差较大的问题,本文提出基于有限元模型的建筑混凝土柱屈曲承载力计算方法.通过有限元模型,对混凝土柱进行有限元数值模拟分析,模拟其屈曲力学性能,判断混凝土柱整体抗屈曲强度,确定屈曲承载力极限时的应力-应变关系曲线,并完成曲线参数计算.此次算法与两种传统算法进行对比实验,对三组混凝土柱试件进行破坏,比较峰值负荷计算值和试验值,结果表明,此次算法减小了峰值负荷的计算误差,此次算法的屈曲承载力计算结果更为准确.     

建筑钢混剪力墙抗震特性数值模拟研究

针对传统的剪力墙抗震特性数值模拟方法中由于试验条件多、参数复杂导致的模拟稳定性差的问题,提出建筑钢混剪力墙抗震特性数值模拟.选用Kent-Park模型模拟剪力墙的混凝土部分,采用Stee102模拟钢筋部分,并定义剪力墙截面,建立建筑钢混剪力墙有限元模型,考虑地震灾害对剪力墙的实际影响情况,确定抗震性能评估参数为承载力、刚度和延性以及耗能,设计对应的计算方式,根据计算结果衡量剪力墙抗震性能.实验结果表明:设计的建筑钢混剪力墙抗震特性数值模拟方法参数影响均衡,能量消耗控制波动值小,控制更精准,其整体稳定性得到了提高.     

雾化器转轴振动特性研究

在考虑陀螺力矩、转动惯量和剪切效应等影响因素下,采用Timoshenko梁理论并结合传递矩阵法给出了雾化器转轴的振动特性的计算方法.数值仿真部分采用二节点梁单元建立了雾化器转轴的有限元模型,并进行模拟,其结果验证了本文方法的有效性和高精度,讨论了转速、雾化轮质量以及陶瓷约束刚度等参数对雾化器转轴振动特性的影响.     

新型燃油系统的计算机仿真

本文数值模拟了一种适合劣质燃油（重油）的新型燃油系统，提出了处理喷油器和燃油分配器边界条件的准维模型以及用于喷油泵边界条件的新模型。该燃油系统已应用于ＭＡＮＢＷＬ６０ＭＣ／ＭＣＥ等大功率柴油机。与常规的数值模拟相比，求解管内流动的二阶双曲型偏微分方程的边界条件发生了很大变化，这是燃油系统研究的难点和关键。模拟结果与试验结果较为一致。本研究还进行了不同功中点变型方案的模拟研究和结构参数的优化设计分析，以满足不同船舶的需要。     

基于APDL桥梁参数化有限元分析方法研究

针对以往桥梁建模方法比较复杂与花费时间较长的缺点,以及有限元分析过程与建模过程脱节的技术问题,以混凝土斜拉桥A字型桥塔为例,提出一种基于桥塔点云模型边界特征约束的参数化建模方法,再运用参数化设计语言APDL编写程序,使得参数化在有限元分析过程中得以继承。此方法最大的特点是在点云模型特征边界约束参数关系基础上建立桥塔的有限元模型,然后根据桥塔实际受力荷载情况进行加载,最后计算模型并提取实验结果。实验结果表明,该方法能快速建立桥塔的参数化模型和提高有限元分析的有效性,进而可以得出桥塔结构的稳定性分析,为桥梁健康保护提供相应的依据。     

复合材料磁悬浮列车车体结构数值模拟(III)——车体结构性能的参数化数值模拟

在磁悬浮列车车体参数化数值模型的基础上,开展参数变化对车体结构性能影响的数值试验,研究复合材料梁截面几何参数对车体刚度和频率的影响。在典型荷载工况下,研究关键设计参数对车体结构性能、结构部件连接模型的力学性能、车体频率和振型、车体结构线性屈曲性能的影响,确定关键设计参数对复合材料车体结构性能的影响趋势,为车体优化设计奠定基础,验证将参数化车体数值模型作为车体结构性能研究的有效性。     

基于动态模拟的危险与可操作性分析在精馏塔中的应用

危险与可操作性分析是化工领域中广泛应用的安全分析的有效方法,近年来其定量化研究已经成为一种趋势.为了实现定量化的危险与可操作性分析,本文提出了基于动态模拟的危险与可操作性分析的新型方法,即在传统的危险与可操作性分析的基础上引入了动态模拟模型,利用动态模拟的定量化弥补传统危险与可操作性分析定量化不足的缺陷.通过对动态模拟模型中操作参数进行不同程度的拉偏可以方便地模拟危险与可操作性分析中引导词与工艺参数组成的偏差,模拟的结果变化就是偏差对系统所造成的影响,以此实现危险与可操作性分析的定量化推理.本文利用对一个萃取精馏塔的冷凝能力缺失和安全阀失效问题阐述了基于动态模拟的危险与可操作性分析方法的新型研究方法.最后,根据案例分析总结了这种新型分析方法的优点,并且研究证明其为一种行之有效且非常有潜力的分析方法.     

结构尺寸对LNG低温螺旋波纹钢管弯曲性能的影响分析

基于ANSYS三维壳模型,依据结构几何尺寸对LNG低温螺旋波纹钢管进行参数化有限元建模.考虑低温环境下材料力学性能的改变和结构几何非线性因素,对弯曲载荷作用下低温螺旋波纹钢管结构力学性能进行数值模拟;分析管体弯曲失效模式和力学行为特点.改变结构几何尺寸,分析比较波峰和波谷极值应力以及管道整体力学性能,发现尺寸参数对低温波纹钢管力学性能的影响显著,分析相应的灵敏度规律,最后给出合理的截面尺寸参数.分析结果可以为低温柔性管道的结构设计提供参考.     

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。     

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。