基于冲激雷达的运动体目标检测算法

针对冲激雷达脱靶量测量中的检测问题,提出了一种新的时域多门限信号检测算法。根据冲激雷达的特点,首先采用距离门等效采样方法对运动体目标回波采样,并在此基础上,利用多门限对各距离门采样信号进行散射点回波的检测,进而通过各散射点回波平均功率的求取实现对各散射点回波的识别,从而解决了后续数据处理中信号检测精度过低和散射点无法识别的问题。仿真结果表明该算法可得到满意的检测结果。     

超宽带探地雷达目标回波信号特征提取与材质识别

基于探地雷达信号传输机理,建立了超宽带探地雷达宽带回波模型,揭示了多谱分量对目标回波信号特征提取与材质识别的影响。超宽带探地雷达由于回波信号信息丰富的特点,特征向量的选取成为目标识别的关键。利用子波变换在宽相关处理中的应用,对回波信号进行滤波和典型数据提取。提取纵向和横向典型数据用于目标形状识别;提取回波道数据进行Welch功率谱分析,用于目标材质识别。     

导航雷达回波信号的实时采集与回放

本文设计并实现了一种导航雷达回波信号的采集方法.在分析采样信号特性及雷达性能参数的基础上,采用PXI系统构建实时采集导航雷达回波信号的硬件平台.在此基础上,利用VC++6.0开发基于Windows操作系统的采集软件,并指出实现过程中的关键问题和解决方案.通过渤海湾某海域的岸基采样实验,证明采样方案的有效性和基于PXI技术采样平台的可靠性.     

同轴电缆形变TDR监测技术的研究与实现

针对时间域反射测试技术在地质灾害防治、山体滑坡预警,以及土壤水含量分析等诸多领域的应用,使用TDR技术构建的同轴电缆形变监测算法,设计了TDR检测系统硬件电路;运用等效采样算法,实现了高速回波信号的等效采样与重构;通过向同轴电缆施加窄脉冲激励信号,依据回波信号模式分析完成了同轴电缆形变的有效监测;实验室中的大量实验数据表明,将TDR技术应用于同轴电缆形变监测原理正确,文中设计的方案可行.     

基于无载频脉冲式超宽带雷达的生命信号检测分析与实现

首先分析了无载频脉冲式超宽带雷达检测生命信号的检测原理,论证了基于频谱搜索检测生命信号的方法;然后介绍了一款新颖的无栽频脉冲式超宽带生命信号检测雷达系统.该雷达发射机结构简单,能产生Vp-p+为2～10 V、脉冲宽度为300～500 ps、脉冲重复频率大于10 MHz的超短脉冲.接收机利用PNP和NPN微波三极管的互补特性,产生一对平衡对称的超短门脉冲控制二极管桥的导通与截止,实现对天线接收到的信号进行采样,从而完成等效采样接收.依据人体呼吸信号的频谱特性,搜索包含具有最大功率谱的生命信号的快时间点、提取位于快时间点和不同慢时间点的雷达信号得到生命信号.实验证明,该雷达系统能实时实现人体生命信号非接触式检测.     

无载频超宽带雷达的梳状谱干扰仿真研究

超宽带雷达的发展及其在军事上的应用,对传统雷达对抗装备提出了严峻的挑战,极宽的信号带宽迫使干扰信号在频域上分散,从而大大降低了干扰信号的有效性.为了集中信号功率,对超宽带雷达进行有效干扰,提出了梳状谱干扰技术,即将干扰功率集中于雷达信号带宽范围内的一些离散频率点实施干扰,破坏雷达回波信号与参考信号的相关性,从而实现有效干扰.以无载频超宽带雷达为研究对象,通过仿真方法,将梳状谱干扰与传统的噪声干扰进行比较,得出梳状谱干扰技术对无载频超宽带雷达具有明显的干扰效果.研究成果对超宽带雷达干扰装备的研制具有一定的参考价值.     

基于嵌入式雷达回波采集电路设计与实现

本文应用等效时间采样工作原理,设计了一种基于FPGA实现的穿墙雷达高速窄脉冲采集电路,电路结构简单可靠.测试结果表明,采集到的回波脉冲波形与发射脉冲基本相同.     

超宽带雷达信号电路的设计与实现

介绍了一种超宽带雷达信号波形产生器的设计与实现,信号由DDS+PLL+混频器产生。该产生器采用高性能数字锁相环芯片Q3236、压控振荡器Q3500-0916T和混频器IAM-81008构成核心单元,利用新型低频和超带宽带通滤波器完成超宽带雷达信号。这种超宽带雷达信号的实现对提高现有雷达的性能以及研制新一代高性能雷达都具有重要意义。     

穿墙脉冲雷达回波信号人体微动特征识别初步研究*

主要研究了超宽带雷达人体探测回波信号微动特征识别问题。在分析超宽带雷达生命特征检测原理的基础上,针对人体微动特征特点,引入能量积分识别算法,编制时窗函数,对雷达实验的多个回波数据进行小波去噪处理。结果表明,利用能量积分算法,可以识别出含有人体微动特征的信号。     

一种新型雷达高度表回波信号模拟器的设计与实现

为了客观评估和测试雷达高度表的动态性能,提出了一种新的脉冲雷达高度表回波信号模拟器的设计思想和实现方法;该模拟器的创新点在于集成了雷达高度表回波信号的两种模拟方法:基于实际飞行试验采集回波的回放和基于数学模型的仿真回波;推导了回波仿真的数学模型,并基于现代仿真与软件无线电技术完成了模拟器的系统结构与各子模块的设计和实现;理论分析及测试结果表明该模拟器能在实验室条件下有效模拟飞行航迹中不同地形地貌条件下的真实地面散射回波.     

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.