自动驾驶仪动特性的局部收敛变结构导引律

针对拦截弹末制导全局收敛设计难度大等特点,在考虑导弹自动驾驶仪动态特性的前提下,提出局部收敛的变结构导引律.在设计过程中,先对局部收敛稳定性理论进行数学描述,然后将控制系统分解为两个子系统,且只考虑视线角速率的变化,使得设计过程大大简化,设计的导引律有效地克服了自动驾驶仪动态延迟对制导精度的影响.仿真结果表明,在目标做正弦机动,自动驾驶仪存在较大滞后情况下,局部收敛变结构导引律仍具有较高的制导精度.     

一种针对机动目标的三维鲁棒导引律

针对球坐标系下的三维导弹与目标相对运动模型,基于零化导弹与目标视线角速度的思想,在不依赖于碰撞线附近线性化的假设的情况下,设计了满足输入-状态稳定性(ISS)理论的非线性鲁棒导引律.该导引律的设计不需对目标机动加速度做自适应估计,在目标运动信息完全未知的情况下可实现对机动目标的扰动抑制、跟踪和拦截.仿真结果表明,所设计...     

改进的考虑自动驾驶仪动态特性的有限时间滑模导引律

为减小导弹自动驾驶仪延迟特性对制导精度的影响,考虑到实际战争中制导末段时间很短,推导了考虑导弹动态特性的有限时间收敛的制导数学模型;其次根据滑模控制理论设计了基于该数学模型的导引律;证明了所设计的导引律在制导系统中有限时间稳定;为削弱滑模导引律的抖振现象,利用双曲正切函数改进了导引律。仿真表明:改进的导引律在目标做非机动和机动的情形下均能在有限时间内快速跟踪目标的运动,并保持较高的制导精度。     

CGF系统中的飞机智能决策模型的研究与实现

计算机生成兵力系统(CGF)中导弹模型作为舰载武器模型的最重要组成部分,其实体建模精度和弹道模拟一直是我们关心的问题.精确制导武器制导律研究中,当略去导弹和制导系统的惯性,将导弹当作可控制的质点时,确定出的导弹飞向目标的弹为理想弹道.在计算机生成兵力系统实际需求下,随着制导精度要求的提高,理想的弹道和理想的比例导引已不能满足要求.该文据比例导引的差分方程,在对比例导引进行三维弹道仿真的基础上,分别对基于二次型的最优制导律、考虑弹体动态特性的二次型最优制导律进行了三维弹道仿真,绘制出了可直观显示的弹道特性,计算了导弹与目标遭遇时间,并对结果进行了比较分析.得出考虑弹体动态特性的二次型最优制导律性能最优的结论.     

基于威胁环境的空战导引律设计

提出一种在威胁环境下对敌空战时,战机导引律设计方法。根据空战中存在的威胁因素,战机在空战过程中首先利用遗传算法进行远距导引设计,规避敌方防空威胁;然后根据滑模变结构理论设计近距空战导引律,并将两种作战机动导引进行融合。基于进化理论来构造规避路径,并利用卡尔曼滤波对机动目标进行状态估计,实现威胁回避和空中交战机动的组合导引。仿真结果表明,该组合导引律能够在复杂环境下有效地完成空战任务。     

越肩发射空空导弹复合制导仿真研究

研究优化制导系统性能,越肩发射空空导弹的特点,要求转向准确攻击目标.为了优化制导系统,用最优控制和H∞控制理论设计全弹道复合制导规律.根据极小值原理,在推力矢量控制下设计了以在给定的时间内,使平行于初始视线方向上的速度分量达到最大,并使终端速度最大为指标的最佳快速转弯的初制导律.对末制导律是利用H∞鲁棒控制理论设计,对目标机动不作任何限制的鲁棒制导规律;然后用这两种制导律的加速度指令为参量构造了一个连续函数作为交接班的导引规律,实现弹道的平滑过渡,并对对全制导段弹道进行数字仿真,结果表明所设计的复合制导律为优化制导系统提供了参考.     

攻击大机动目标的变结构末制导律设计

研究优化末制导的性能问题,针对导弹动态系统的非线性关系,通过分析导弹和目标的相对运动系统状态方程的可观性,为了攻击大机动目标,提出修正极坐标系,根据非线性系统鲁棒控制理论和滑模变结构理论来设计导弹的末制导律,实现对目标机动加速度的界进行在线估计,同时保证系统稳定.把制导律应用于导弹系统并进行仿真,结果表明,导弹和目标的视线角速度趋于零,从而保证目标拦截成功.证明导弹制导算法对大机动目标有较强的鲁棒性,制导律应用于导弹攻击大机动目标是有效的.     

考虑自动驾驶仪动态特性的三维双环制导律

针对导弹自动驾驶仪动态特性条件下的机动目标拦截问题,基于非线性干扰观测器和命令滤波器设计一种新的三维双环制导律.将制导系统解耦为外环系统和内环系统.其中:外环控制器产生虚拟制导指令,以零化球坐标系下的弹目法向相对速率;内环控制器产生真实制导指令,以实现导弹自动驾驶仪对外环虚拟指令的快速跟踪.由于外环命令滤波器同时计算出虚拟制导指令的一阶导数和二阶导数,三阶系统的制导律设计问题仅用两步即可完成.拦截高速高机动目标的仿真结果表明,所设计的制导律能够有效补偿导弹自动驾驶仪动态特性影响,抗目标机动鲁棒性强,制导精度优良.     

基于红外成像导引头的切换制导律设计

根据对红外成像导弹多模制导技术研究的现有成果,设计了适合红外成像导引头的制导律.分析了红外成像导引头不同阶段的成像特点,根据这些特点选择相应的制导律.这些制导律很好地弥补了红外成像导引头的成像缺点,并结合弹道交接算法完成制导功能.数字仿真验证了切换制导控制导弹攻击大机动目标较比例导引有更小的脱靶量和更平滑的弹道.结果表...     

一种基于零脱靶量的最优制导律设计

基于导弹和目标的三维相对运动关系,提出了一种三维非线性的最优制导律.在导弹和目标的三维相对运动方程的基础上,区别于以往的以视线角和视线角速率作为状态变量的方法,而采用以相对距离和相对速度作为状态变量的方法建立了一种新的状态方程,然后基于零脱靶量的思想,利用最优控制相关理论,设计了一种三维非线性的最优制导律.分别针对匀速运动的目标和大机动目标,用所设计的制导律和比例导引律分别进行了数学仿真,结果表明,所设计的最优制导律能有效地拦截机动目标,其性能优于比例导引律.     

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.