反舰导弹抗干扰试验与评定仿真系统设计

现代反舰导弹处于复杂的海情,电磁环境密集交迭,电磁干扰方式复杂多变的高技术海战场作战环境下,因此在靶场试验过程中很难对反舰导弹所处实战干扰环境进行模拟.通过对雷达系统、雷达干扰信号仿真模型进行分析,并运用面向对象技术,研究设计了反舰导弹抗干扰试验与评定仿真系统,其中包括类库的构建以及诸对象之间信息传递的实现,试验设计系统的系统流程、数据流程及结构的设计.该仿真系统可用于反舰导弹抗干扰仿真试验及抗干扰能力评估.     

基于虚拟仪器的DRFM干扰模拟器设计

为满足雷达对抗数字射频存储(DRFM)干扰的技术验证和系统测试需求,采用矢量信号收发仪结合DRFM技术设计了一种模块化、可扩展、轻量便携的干扰模拟器,采用一种流控制器实现对干扰模拟器的控制,并通过雷达和干扰模拟器的注入测试验证了设计的有效性。该设计能根据雷达回波产生包括间歇采样转发干扰在内的多种类型雷达干扰信号,能通过更换、扩展板卡实现多种任务功能,可用于雷达测试环境构建,有力支撑了雷达抗干扰技术的研究与验证。     

PD雷达有源干扰系统的计算机仿真

为了方便有效地对PD雷达进行干扰抗干扰技术研究,需要利用某种计算机仿真技术,建立一套仿真系统,最大程度地模拟PD雷达干扰环境.基于此目的,文章首先描述了PD雷达发射信号的数学模型,重点研究了常见的两种PD雷达有源干扰方式及其作用机理,并采用MATLAB/SIMULINK仿真技术对信号,干扰等模块进行建模.仿真结果显示,建立的模型可以有效模拟对PD雷达实施的各种干扰.建模过程简单有效,因此,可以在该系统上进一步进行干扰手段改进或者抗干扰性能的仿真,有助于PD雷达干扰抗干扰技术的研究.     

复杂电磁环境雷达新型威胁信号建模与仿真

复杂电磁环境中雷达新型威胁信号相对传统威胁信号具有更强的相干性和隐蔽性,信号环境对雷达装备构成较大威胁。针对目前对该类环境信号干扰机理和数学模型欠缺系统性研究的问题,分析了环境的组成要素,并对典型的信号样式建立了数学模型。最后,研制开发了雷达信号环境全数字仿真模拟系统,在该系统上实现了信号模型的仿真验证。仿真结果表明了模型的合理性和有效性。     

基于UML的雷达电磁环境仿真系统建模

雷达电磁环境仿真研究,对于雷达装备试验、训练都有着十分重要的作用.本文以飞机空中突防作战为战术背景,进行一个虚拟战场雷达电磁环境仿真系统的设计.以面向对象仿真技术为基础,利用可视化建模语言UML,详细描述仿真系统的建模过程,给出部分仿真模型和分析实例.     

C~3I系统警戒雷达数据源的模拟与仿真

针对目前高炮情报指挥系统模拟训练器功能相对单一,难以满足模拟训练和系统测试这一现状,提出了一种基于嵌入式环境的多雷达多目标空情录取系统模拟仿真方案,重点研究多目标航迹生成方法和警戒雷达功能仿真模型。系统采用模块化设计思想,分别建立了以目标状态模型为核心的航迹模型、警戒雷达功能仿真模型以及嵌入式数据库。雷达功能仿真模型的建立充分考虑了影响警戒雷达探测能力的内在因素和外在干扰。系统模型经检验符合实际要求。     

用于雷达系统信号处理的有限冲激响应滤波器设计

考虑复杂环境下噪声干扰信号对机载雷达系统的影响,分析了噪声干扰模型,建立一种基于Remez变换算法的线性相位FIR数字滤波方法,并进行了仿真比较。结果表明,这种方法能有效地抑制雷达接收端的噪声干扰,显著提高信噪比,有效地对雷达系统中的复杂信号进行处理,为综合评价雷达作战效能提供了重要的参考价值。     

雷达有源干扰过程仿真研究与设计

在有源干扰效果优化问题的研究中,雷达有源干扰能力是电子对抗作战效能重要的组成部分.传统的仿真过程常常是通过判断干扰信号中心频谱宽度与雷达接收机中心带宽的覆盖情况来判断干扰成功与否,使得判断条件过于单一、绝对.针对上述问题,提出一种新的判断条件对多种干扰波进行分析.引入了最佳干扰波形,与其它干扰波形进行比较,判断是否干扰成功.实验结果表明,干扰信号与最佳干扰信号之间的偏差,能测量出它们相对于最佳干扰信号在遮盖性能上的损失,从而评估干扰效果,计算干扰成功几率,证明仿真效果更加真实.     

复杂电磁环境下防空雷达的探测模型研究

现代战场处于复杂的电磁对抗环境之中,在空袭与防空作战中,制电磁权的斗争集中表现在雷达领域,防空雷达的探测模型是防空作战仿真中不可或缺的重要模型.传统的雷达模型对复杂电磁环境考虑的不够,模型通常为距离模型而非概率模型,并且模型参数过于复杂,不适合大规模作战仿真的需要.针对复杂电磁环境下电子对抗和雷达装备的特点,在雷达距离方程的基础上,对雷达探测的某些问题做了合理的简化,参考雷达探测的BLAKE图解法,采用功能性仿真,计算统计意义上的雷达探测概率,建立了雷达探测的概率模型和仿真算法.通过仿真结果与相关型号试验数据的印证,表明模型能够确切反映相关雷达的真实作战效能,适合作战仿真的需要.     

一种卫星导航抗干扰接收机的室内无线测试方法

卫星导航抗干扰接收机室内无线抗干扰测试具有成本低、可控性好、重复性强等优点,因此得到了广泛的应用.已有室内无线抗干扰测试方法中卫星信号采用单天线输出形式、干扰信号采用静态干扰模拟方式,无法在空域上模拟卫星空间位置关系及真实的干扰场景,因而不能准确地测试出接收机的抗干扰性能.针对这个问题,提出了一种基于微波暗室的大视场角卫星导航抗干扰接收机的测试方法,通过扩大模拟信号的视场角,实现卫星信号多天线输出、干扰信号动态模拟.通过数字仿真与实测结果对比分析,验证了本文所提出的测试方法的有效性与合理性,并分析了信号模拟误差对抗干扰接收机测试带来的影响.     

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.