一种新型滑模变结构导引律的研究

针对导弹拦截问题,在非线性系统滑模变结构控制理论的基础上,提计出一种新型滑模变结构导引律;该导引律将目标机动视为干扰,而且仅利用了目标加速度界限的信息,在拦截过程中不需要精确的测量目标加速度,因此该导引律对目标机动具有较强的鲁棒性;在执行上,只用到了视线角速率,因而实现简单;仿真结果表明,所提出的导引律在脱靶量、拦截时间等方面优于比例导引律。     

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。     

无人机空中加油过程中分数阶滑模会合导引控制

针对带末端角度和末端速度约束的无人机空中加油自主会合问题,设计了一种3维分数阶滑模导引律,使无人机在无加油机主动配合的情况下具备自主会合能力.首先,根据无人机与加油机之间的相对运动关系,设计了3维比例导引规律,使无人机能够到达期望的加油位置.其次,利用滑模控制的强鲁棒性特点以及分数阶微积分的精细控制特性,基于变结构理论和李雅普诺夫稳定性理论设计了一种带有末端角度约束的3维分数阶滑模变结构控制律,并用所设计的分数阶滑模控制律对3维比例导引指令进行重构,使无人机能以期望的末端追踪角度到达加油位置.然后,构造了速度指令生成器,对无人机的末端速度进行约束.最后,对所设计的导引律进行了仿真验证,仿真结果表明所设计出来的导引律能满足追踪角度和速度约束的要求.     

空空导弹变结构末制导律研究

在空空导弹末制导段中,为了提高对目标未知逃逸机动的鲁棒性,提出了变结构末制导律。以零化视线角速度为切换面设计了末制导段针对目标逃逸的变结构制导律,研究了将目标机动作为干扰情况下变结构制导律满足稳定性的条件。针对变结构制导律中滑动模态的颤振问题,提出用一次函数取代传统变结构制导律中的符号函数,从而对变结构制导律加以改进而改善由于符号函数而产生的滑动模态的振颤现象。仿真结果表明,提出的经过改进的变结构制导律结构简单,易于实现,且具有良好的导引精度。     

一种新型自适应RBF神经网络滑模制导律

针对导弹拦截问题,提出一种自适应RBF神经网络滑模制导律．首先根据准平行接近原理和变结构控制理论设计滑模面,然后将滑模面作为RBF神经网络的输入变量,输出量即为导弹的加速度．为了使得导弹系统能够到达滑模面,采用自适应算法实时在线调整RBF神经网络的连接权值．该导引律将目标机动视为干扰量,在拦截过程中不需要测量目标加速度,因此该导引律对目标机动具有较强的鲁棒性．在执行上,只用到了视线角速率,因而实现简单．仿真结果表明,所提出的导引律和比例导引相比在脱靶量、拦截时间等方面有了很大的提高．     

弹道坐标中三维鲁棒非线性导引律

本文针对机动目标拦截问题,考虑导弹控制系统动态特性及其不确定性,利用分块反步设计思想,结合输入-状态稳定性理论,在弹道坐标系中设计了一种三维非线性鲁棒导引律.与大多数已有的导引律相比,本文直接地在弹道坐标系中设计导引律,并且所设计的导引律可有效克服控制系统动态特性和不确定性对制导效果的影响,理论分析和数值仿真表明,本文设计的导引律对目标机动和控制系统所受的外来有界扰动均具有较强的鲁棒性.     

基于比例导引律的无人机避障研究

随着无人机作战环境日益复杂,无人机避开动态障碍物的研究成为热点问题.为提高导引避障性能,借助比例导引律的思想,通过使无人机与动态障碍物的相对速度方向导引到避障向量方向,完成避障.为满足避障完成时间和无人机机动性能约束要求,给出了避障时间估计和法向加速度表达式,通过解算得到了比例导引系数取值范围.避障完成后无人机在避障点可用比例导引律进行路径规划,最后到达目标点.仿真结果验证了算法的有效性.     

红外制导导弹最优导引律工程实现方法研究

为了研究提高导引精度,用最优控制理论推导出的最优比例导引律,给出了一种只需目标视线角速率信息的最优比例导引律工程实现方法,方法不需要最优比例导引律中的相对速度、目标加速度和剩余时间等信息,与基于小离轴角的假设推导得出的经典的比例导引律相比,可满足近距格斗导弹大离轴发射和攻击高机动目标的要求。经仿真结果证明,最优比例导引律的工程实现方法尤其适合不带测距功能的红外制导导弹,与需要剩余时间估计算法的方法相比具有更强的工程可实现性。     

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...     

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.     

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。