天波雷达海杂波功率谱建模与仿真

海杂波功率谱建模,是定量研究天波雷达海杂波频域特性从而为评估天波雷达对海探测性能提供理论依据的前提和难点.传统的基于产生机理的Barrick海杂波模型没有考虑天波传播环境影响,且只能获得海杂波后向散射系数值,无法获得天波雷达海杂波功率谱值和准确的变化规律.为解决上述问题,引入电离层展宽、电离层吸收损耗和洋流影响计算模型,建立了要素完整的天波雷达海杂波功率谱数学模型.根据上述模型,利用matlab软件仿真分析了不同条件下海杂波功率谱的变化特性.仿真结果表明,所建模型可获得与定性分析一致的结论,能够较好地近似实测数据,证明了模型的有效性.     

地杂波背景中机载预警雷达作用距离分析

针对不同地杂波环境对机载预警雷达最大作用距离影响程度的差异.在分析地杂波特性的基础上.推导出杂渡环境下机载预警雷达作用距离方程,得出了典型杂波环境下机载预警雷达的作用距离.最后选用适当参数进行仿真,结果表明该方法的正确性.     

高频双基地雷达海杂波数值仿真

海杂波是高频雷达海态信息的重要载体,也是影响高频雷达海面低速目标检测的重要因素,针对高频双基地雷达在定位精度精确性和反隐身问题上起重要作用.为了准确检测海杂波海态参数信息,利用数值仿真方法对双基地海杂波的特性进行研究.在分析双基地一阶和二阶海杂波形成机理的基础上,利用海杂波雷达散射截面方程,对高频双基地海杂波进行仿真.针对复杂的二阶谱仿真,采用固定波数下二阶子谱叠加方法,避免了求解非线性方程,并在仿真中采用角频率离散化方法,提高运算速度.仿真结果表明双基地海杂波不仅与雷达海态和雷达工作频率有关,还与双基地角密切相关.结果证明方法有效,为目标检测提供科学依据.     

基于改进粒子群优化的机载预警雷达组网

研究空中机载预警雷达优化设计问题,两部或多部机载预警雷达如何部署,才能充分发挥机载预警雷达的战术效能,满足最大限度地监控随作战态势的发展而变化的重点监控区域的需要.为提高现代战争中空中预警的性能,提出一种改进的粒子群优化算法,对机载预警雷达组网中的部署问题进行优化.首先假定机载预警雷达探测范围是没有盲区的理想圆形区域,得出一个优化的组网试验,再进一步进行有盲区机载预警雷达活动范围受限时的组网试验.最后,提出一个预警机按特定航线巡航状态下优化试验方案.实验结果表明,改进方法行之有效.     

一种对抗机载PD雷达的主瓣杂波隐匿方法

机载PD雷达进行下视探测时面临严重的地海杂波,在电磁战场空间中合理利用地利用目标雷达的这一特性,可以取得隐匿我方作战力量的效果。基于己方平台各装备的侦察数据、结合当前运动状态,本文提出一种反演目标机雷达杂波谱及载机所处位置的方法,进而给出战术规避建议,降低被雷达检测到的概率,仿真结果验证了该方法的有效性。     

基于STK的相控阵雷达反隐身探测效能分析

为了解决针对隐身飞机的防御研究中,相控阵雷达对隐身飞机的探测效能计算这一问题,使用STK仿真软件为手段,提出了一种相控阵雷达的建模仿真方法。后在针对某型隐身飞机的预警作战仿真中,使用该方法建立模型并对其探测效能进行了分析。最后,提出了针对反隐身预警体系建设的部分思路。     

机载预警雷达探测空间动态性能分析

机载预警雷达的动态探测性能尚无统一的度量标准。该文针对双平行线的一般情况，采用相对运动的方法，以目标进入雷达探测区的概率为指标，对影响机载预警雷达探测空间的三个主要因素——载机-敌机速度比、平行线长度-探测半径比和平行线间隔-探测半径比，给出定性和定量的分析，运用蒙特卡洛法仿真计算，并得到更一般的结论：在满足作战需要的前提下，对于均匀分布的匀速目标，应增大载机速度，减小巡逻边长与探测半径之比，以提高机载预警雷达探测空间动态效能。对于目标非均匀分布，以及载机采用其它巡逻航线的情形，本文所给方法同样适用。     

雷达地杂波建模与仿真实现

地面雷达设备在探测和跟踪目标时,会受到杂波的干扰,特别是雷达的俯仰角较低时,受地物杂波干扰更为严重,虽然现代雷达采用动目标显示等技术来抑制地物杂波,但其影响仍然存在.在研究地杂波仿真技术的基础上,提出了采用数字高程模型和杂波模型相结合的思想,重点对地杂波进行仿真.     

双峰谱模型在风切变雷达目标检测中的应用

针对低空风切变的检测问题,提出了一种基于机载风切变雷达回波信号的双峰谱参数模型,利用该模型对回波信号频谱进行拟合分析,省略了预滤杂波处理环节,可以直接对风切变目标进行探测。该模型中的两个参数,平均风速和方差,是风切变现象的两个特征参数;把双峰谱频谱模型同风切变雷达回波仿真频谱作了仿真和对比分析,提取出风速等参数;结果表明,双峰谱模型较好地拟合了回波信号频谱,证实了双峰谱模型的有效性,在低空风切变雷达中有一定的应用前景。     

机载有源自卫干扰下雷达探测效能仿真

随着现代电子战的快速发展,机载自卫有源干扰成为了对抗雷达最有效措施之一,严重威胁雷达探测效能与生存能力。从作战效能评估需求出发,选取探测概率作为定量评估指标。首先把雷达探测过程分解成不同功能模块,通过各模块的有机结合构建探测模型,并详细介绍了各模块数学模型。然后,对雷达动态探测过程进行功能仿真,并基于HLA平台开发仿真系统。最后,通过仿真,能在线获得对应目标距离的探测概率,并以此定量分析了有源自卫干扰下雷达探测效能。仿真结果验证了模型和方法的可行性与有效性,对雷达反对抗研究提供一定的参考依据。     

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     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

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。