深水锚缆水下运动三维优化仿真研究

深水锚缆在波浪、海流等环境载荷的作用下在三维空间内产生运动,形成较为复杂的运动轨迹构形,对锚缆浮式结构产生了较大的作用力,存在锚缆在环境载荷作用下的大位移、大转动的几何非线性干扰.传统的基于悬链线理论的三维运动仿真方法在非线性干扰的情况下,无法准确仿真三维浮动特征点,仿真效果较差.为此提出一种新的锚缆三维运动仿真的方法.针对锚缆在环境载荷作用下的大位移、大转动的几何非线性问题,采用细长杆模型和拓展的拉伸方程进行时域三维数值计算仿真;结合三维图形库VPython解决缆索的三维模型的可视化抖动问题,并借助多线程方法提高仿真效率.以数据文件作为数值计算程序和可视化仿真程序进行仿真.结果表明新方法较为完善地联接了锚泊系统运动仿真的核心计算模块和后处理模块,锚泊运动仿真过程计算准确快速、可视化仿真效果流畅.     

基于EnSight的数值仿真可视化系统设计与实现

为提高数值仿真后处理的效率,满足分布式仿真系统在数值仿真数据方面的可视化需求以及实现仿真试验过程的可视化,基于EnSight的二次开发开展数值仿真可视化系统设计.提出基于Qt开发框架的系统集成、基于Python的功能开发和基于Socket的通信接口开发,实现具有协同功能的数值仿真可视化系统.该系统采用模板化技术实现带场景的可视化和快速后处理功能.给出系统架构、组成、实现效果及应用案例.应用结果表明：该系统能够适应多仿真类型结果分析,实现动态仿真过程的协同可视化.     

热载荷作用下透镜面形精度分析方法

为了分析透射式光学系统中透镜在热载荷作用下的镜面面形精度,建立了光机结构模型,使用有限元软件对热载荷作用下透镜的镜面变形量进行了分析,通过matlab软件对变形后的节点位移进行拟合,进而求出在指定热载荷下透镜的面形精度。该分析方法还可以对其他载荷引起的镜面变形进行分析,为透镜面形精度分析提供参考。     

刚体破碎特效仿真研究

破碎是真实世界中普遍存在的物理现象,刚体破碎仿真也在各领域中被广泛应用.本文分别从基于物理和基于非物理的建模方法产生的不同刚体破碎特效,阐述分析刚体破碎仿真的研究现状,结合当下研究和现存问题给出相关建议,并对下一步的刚体破碎研究做指引.     

跨声压气机转子进口总压畸变的数值仿真

研究燃气涡发动机问题,进气畸变会严重影响压气机的稳定性,针对目前对进气畸变问题研究的不足,为提高工作稳定性,利用全三维定常数值仿真方法研究了一跨声压气机转子在不同类型的稳态总压畸变入口条件下的特性,并对比分析了三种典型转速工况下稳态周向总压进气畸变对压气机转子的影响并进行仿真.仿真结果表明,在设计转速,相同进气畸变强度下,径向叶尖畸变时转子的性能和稳定性的降低最大,而径向轮毂畸变时转子的稳定裕度有所提高,证明系统的性能得到改善.     

振动对反射镜胶连接的影响分析与试验

在空间相机反射镜连接优化的研究中,胶连接是空间相机反射镜连接常用的连接方式之一。在相机振动试验、发射等力学环境作用下胶接连接状态、胶接力可能会发生变化。胶连接状态的变化使反射镜镜面面形发生变化,导致相机成像质量变差。目前尚无直接测量反射镜胶接力在振动力学试验前后变化的方法,直接采用完成镜面加工的反射镜进行振动试验,势必增加了反射镜研制风险。为了研究振动对反射镜胶连接的影响,采用设计胶接试验件的验证方法,将检测胶连接状态的变化转换为光学测量镜面面形的变化,解决了直接测量的胶连接变化难的问题。振动试验前通过有限元的方法仿真分析了力胶接试验件的动力学特性,为力学试验条件制定提供了参考。通过对比振动试验前后胶接试验件面形RMS值,胶接试验件面形最大变化为1.26nm,在设计和光学测量误差变化允许范围内,表明改进的反射镜胶连接方法有一定可行性,为验证振动对胶连接的影响提供一种新方法。     

卫星表面光学反射特性建模与仿真研究

在研究空间相机成像效果探测问题时,针对提高探测相机成像真实效果的需要,研究了卫星表面光学反射特性的建模与仿真方法.利用双向反射分布函数(BRDF)仿真卫星表面的光学反射特性,将卫星表面物理特性与其光学反射特性有机地结合起来.在VC.Net环境下开发卫星表面光学反射特性仿真软件,并将软件集成到空间探测相机成像效果仿真平台上.利用平台进行成像仿真实验,生成真实感仿真图片.仿真结果表明,BRDF能够精确仿真卫星表面的光学反射特性,使成像效果仿真更加准确和逼真.     

弹体毁伤机场跑道的数值仿真

论述了用基于AUTODYN的动力学分析有限元程序对弹体毁伤机场跑道靶板过程进行数值仿真.阐述了数值仿真模型的建立,以及利用数值模拟技术,实现了毁伤过程中弹体的变形与靶板的破坏状况可视化,同时对仿真结果进行了分析,并进行了实验验证,仿真结果与实际情况基本相符.并且还分析了不同打击条件下弹体对机场跑道靶板的毁伤情况.通过对弹体毁伤机场跑道过程的数值仿真,为开展弹药的毁伤效能评估以及准确预计机场跑道的抢修任务和保障力量准备提供数据支持.     

两栖车辆水上加速性能数值仿真研究

在两栖车辆的设计阶段,数值仿真是预测车辆水上航行性能的有效方法。基于计算流体动力学理论和刚体动力学理论,对两栖车辆的水上加速运动进行数值仿真,并对两栖车辆的加速性能进行了预测。通过对车辆结构参数的计算,得到了两栖车辆的航行推力特性。利用刚体六自由度运动和自由水面耦合的方法,计算了车辆的航行姿态,采用动网格技术实现运动边界。计算结果表明,两栖车辆的水上加速性能基本上达到了设计要求,同时也说明数值仿真方法可以有效地预测两栖车辆的水上加速性能。     

光学仿真软件的系统架构设计

针对当前光学仿真技术的发展,为了更好的对光束在光波导器件中的实际传输过程进行仿真,从而更为准确地分析和描述光学现象及光学过程,在有限差分光束传播算法理论基础上,采用模块化方法设计光学仿真软件系统架构。系统架构主要包括布局编辑、仿真计算以及图形输出等三个模块,各个模块间通过接口进行数据处理。根据系统架构模块分析开发的光学仿真软件完成了各种光波导器件的编辑绘制、场分布计算以及波导仿真结果的图形可视化输出,并通过仿真实例的仿真过程及结果的数据对比分析验证了该软件系统设计对光束传播过程仿真的有效性,以及在集成光学研究中的实用价值。     

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.