基于复合制导的中/远距空空导弹仿真

中/远距空空导弹攻击距离远、杀伤力强,成为空战致命武器,弹道轨迹和攻击区的解算是对其仿真研究的核心内容.由于空空导弹大都采用复合制导,初始阶段采用惯性导航法,末段采用雷达制导或红外制导,仿真研究复杂且精度较差.为此提出将惯性导航部分分为机载计算机输出轨迹模型和无线电修正,忽略了惯导内部复杂的制导机理.采用比例导引法和运动方程相结合,同时充分考虑导弹速度特性和可用过载,使仿真简单易行.进行了惯导加红外制导导弹仿真,结果表明,就弹道轨迹和攻击区与真实导弹进行比较,改进算法简化了运算过程,提高了精度,具有有效性.     

一种新的具有攻击角度约束的末制导律设计

研究导弹末制导性能优化问题,在末端要满足攻击角度的约束条件,要求优化空地导弹末制导命中目标精度性能.针对导弹和地面目标所形成动态系统的非线性运动学关系,通过分析导弹在终端命中点角度约束条件,并利用零化视线角速率的设计思想,根据滑模变结构控制理论,提出了一种非线性滑模设计方法,得到了具有攻击角度约束的导弹的末制导律.同时利用Lyapunov稳定理论严格证明了制导系统的全局渐近稳定性.把末制导律应用于导弹系统并进行仿真,结果表明,在不需要任何目标运动信息的情况下,导弹都能获得期望的攻击角度约束和制导精度,证明导弹制导算法对地面目标有较强的鲁棒性.     

基于跃升-俯冲投弹的无人机攻击方法研究

针对无人机投掷非制导炸弹命中精度低的问题,由于炸弹命中率精度与无人机航迹有关,为提高命中精度,提出了一种跃升-俯冲投弹攻击方法.通过研究炸弹的运动学规律和无人机机动性能约束条件,求解出炸弹投放点位置;设计快速生成跃升-俯冲攻击全过程航迹;运用蒙特卡洛法分别对无人机水平投弹和跃升-俯冲投弹进行仿真,结果表明,采用跃升-俯冲攻击方法,可以有效提高炸弹投掷精度,对提高无人机作战效果有重要意义.     

导弹攻击下带矢量推力无人战斗机逃逸概率分析

无人战斗机逃逸概率是无人机设计的重要指标之一,提高无人机飞行时的可用过载能够提高其逃逸概率,另外无人机的机动也对其逃逸概率有重要影响,如何评判在各种机动情况下无人机对导弹的平均逃逸概率与其过载的关系是无人机设计师和军方十分关注的问题;论文以带矢量推力无人战斗机(UCAVVT)作为研究对象,建立其飞行动力学及导弹导引飞行控制数学模型,通过预先假定无人机做典型机动的概率,由计算机仿真导弹与无人机的相对飞行轨迹,研究讨论在各种机动下UCAVVT在导弹攻击下的平均逃逸概率,并对计算结果进行了分析,得出了一些重要结论,对带矢量推力无人战斗机的总体设计具有一定的参考价值。     

多无人机协同攻击路径规划研究

如何实现多架无人机规避复杂威胁区域对敌重要目标实施协同打击成为近来研究的难点,研究实现协同打击的关键是规划出多无人机从各自起始点到目标的最优协同攻击路径,以解决路径规划的关键技术为目的。对复杂威胁区域中,多无人机最优协同攻击路径规划进行了研究。首先,构建了多无人机最优协同攻击路径规划系统框架;其次,以人工智能A*算法为基础,结合无人机运动学方程对A*算法进行了改进,得到一种基于步长搜索的无人机路径快速生成算法;再次,基于改进的路径快速生成算法,以多无人机同时攻击目标为约束条件,进行变步长的协同攻击仿真计算。仿真验证了路径规划算法和协同攻击算法的有效性。     

机载视觉探测与目标定位系统设计与实现

为了解决GPS(Global Position System)定位精度不够高,无法满足无人机完成货物搬运任务的问题,设计并实现了一种以TMS320DM6437为平台的机载视觉探测与目标定位系统,由机载子系统和地面监视子系统组成。机载视觉信息处理子系统利用圆的几何特性改进了经典的Hough变换圆检测算法,在保证精度的同时大大降低了计算量,提高了算法运行效率。同时设计并实现了区分多个相同目标的方案与算法,其冗余机制增强了方案的可靠性。最后搭建了静目标定位测试平台和动目标定位跟踪机载测试系统,验证了系统的可靠性、鲁棒性、实时性和探测精度。     

拦截大航路目标的终端角度约束中制导律设计

研究舰载防空导弹制导精度优化问题.拦截大航路反舰导弹会造成弹目交会角较大降低引信频谱识别的启动概率而不利于引战配合,过去的终端角度约束制导律在逆轨拦截时容易造成末段过载过大甚至发散,使导弹末段可用过载不足而脱靶.为解决上述问题,提出导弹圆周运动过载稳定,利用几何方法设计了一种具有终端角度约束的圆周中制导律,根据圆的几何特性精确计算出了中末制导预测交班点和中制导起始时刻的最优到位角.通过仿真,验证了上述制导方法在过载平稳性、收敛性以及脱靶量等方面的性能优于一般的终端角度约束制导律.证明上述方法解决了终端角度约束造成的末段过载过大甚至发散的问题,有效提高了对大航路反舰导弹的逆轨拦截精度.     

基于Riverbed的机载电子板卡红外图像分割

在机载电子板卡故障诊断过程中,需要对故障芯片进行准确的定位。针对机载电子板卡芯片布局紧密、工作芯片的热辐射范围广的问题,提出一种新型的人机交互式红外图像分割方法。首先,利用基于图像森林变换的Riverbed算法对故障目标图像进行边界追踪,并将Live Wire的特性与之相结合,优化了对边界模糊的目标的轮廓的提取,显著减少了所需的定位点数;然后,鉴于芯片的外形特征,采用基于梯度幅度直方图和类内方差最小化的自适应方法找到芯片的边界,用得到的芯片边界对目标轮廓进行约束,提高目标区域定位的精度。实验结果表明:该方法有效提高了故障边界提取的速度,与其他经典算法相比较有效提高了芯片的核心发热区域提取的精度,避免了多分割的现象。     

多无人机辅助移动边缘计算中的轨迹优化

在无人机辅助移动边缘计算网络中,优化无人机的飞行轨迹可以显著提升无线网络的各项性能指标。该文主要以加权最小化无人机的飞行能耗和接收卸载任务的能耗为目标,考虑满足无人机自身的机械特性和多无人机之间飞行轨迹需满足碰撞避免的约束条件,协同优化多架无人机的飞行轨迹和无人机与地面设备之间的卸载决策参数。建立的基于能耗最小化的多无人机飞行轨迹的优化问题中,目标函数非线性,约束条件非凸。针对这些问题,通过引入辅助变量转化非凸的优化条件,并通过连续凸优化的方法转化非线性的优化问题求解。仿真结果表明,所提多无人机的轨迹优化算法,较好地优化了所有无人机的飞行轨迹,在保证所有地面设备任务卸载完成的前提下明显改善了无人机的能耗性能。     

终端角约束鲁棒制导律设计

研究优化制导系统性能,攻击具有终端角度约束地面目标的制导精度问题,存在测量误差的影响。为了提高精确制导律,提出一种考虑信噪比影响的H"非线性末制导律。以导弹与目标在纵向平面内的二维相对非线性运动为研究对象,建立弹目运动学模型,考虑信噪比的影响,以攻击末端姿态角度误差及控制能量最小为性能指标,基于准平行准则根据H∞理论设计鲁棒末制导律,并用Lyapunov稳定性理论严格证明了制导系统的全局渐近稳定性。最后根据制导精度及角约束条件给出量测系统测量信号的信噪比进行仿真,结果表明,设计的末制导律满足终端角度约束的要求,并提高了制导精度,为系统提供了依据。     

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.