天波超视距雷达数据关联跟踪算法现状研究

在远程预警系统中,天波超视距雷达以其探测距离远、覆盖范围大和抗隐身等优点受到各国学者的广泛关注。但其存在的"三低"和"多径"——低检测概率、低测量精度、低数据率和多传播路径问题给目标跟踪带来很大困难。探讨了天波超视距雷达目标跟踪数据处理算法目前存在的一些问题,回顾了目前天波超视距雷达数据关联跟踪算法研究的发展现状,讨论了基于不同坐标系的天波超视距雷达数据关联跟踪算法的优缺点,并指出了应重点研究的方向。     

基于UKF的超视距雷达跟踪算法研究

天波超视距雷达跟踪目标时电磁波是通过电离层的折射传播的,因而导致在地理坐标系下的量测方程中存在强非线性,而采用传统的EKF（Extended Kalman Filter）实现的跟踪算法,在非线性方程的线性化中舍去了含强非线性的二阶以上的高阶项,导致目标的跟踪精度较低;提出采用UKF（Unscented Kalman Filter）方法处理超视距雷达系统在跟踪算法中的强非线性问题.UKF算法有效降低了非线性方程中的舍入误差,可确保三阶以上的精度.仿真结果表明UKF滤波算法较EKF算法提高估计精度.     

天波超视距雷达的坐标变换

传统超视距跟踪算法多在雷达坐标系下实现。为了避免加入独立的坐标配准算法,严格推导了天波超视距雷达坐标系与地理坐标系之间复杂的非线性坐标变换关系,得出了相应的变换公式,以直接得到目标在地理坐标系下的状态估计。比较发现,目前公开的雅可比矩阵存在两处错误,最后给出了计算机仿真证明,仿真结果表明我们推导的公式是正确的。对于发现的错误给出更正说明。给出的坐标变换法可与相应的跟踪算法结合,得到独立的地理坐标系下的天波超视距雷达跟踪算法。     

改进UKF算法在天波超视距雷达中的应用

针对传统的无损卡尔曼滤波(UKF)算法在对天波超视距雷达进行目标跟踪的过程中存在滤波发散和初始收敛速度慢等问题,提出一种改进的UKF算法。通过引进调节因子对状态矢量和观测矢量的协方差作实时调整,以达到提高滤波结果中状态信息与观测信息的正确率和雷达跟踪系统性能的目的。仿真结果表明,该算法在处理目标跟踪问题时,既可有效抑制UKF算法的发散,又可提高跟踪系统的收敛速度。     

基于多频特征的OTHR目标分类性能分析

天波超视距雷达(OTHR)的目标分类识别方法与常规雷达有着很大的区别;由于目标对不同频率的入射波所返回的信号不同,可直接用合理配置在几个频率点上的RCS数据进行目标分类识别;在仿真模拟OTHR的目标回波及电离层模型和构建目标RCS特征库的基础上,针对部分空中目标,利用多频法进行目标分类识别,进行了大量仿真实验和性能分析;通过对比在不同频率点数和不同外加噪声情况下的分类识别结果,验证了多频法在OTHR目标分类识别中的有效性和可行性.     

基于改进Camshift的穿墙雷达运动人体目标成像跟踪算法

针对穿墙雷达运动人体目标图像"闪烁"与"抖动"的特点,提出基于改进Camshift的穿墙雷达运动人体目标成像跟踪算法。首先,针对形成的连续多帧穿墙雷达图像以及对应的颜色概率分布图,引入目标预测过程以确定图像中运动目标搜索波门,消除波门外的杂波干扰;然后,利用颜色概率分布图,在波门内自适应迭代调整目标搜索窗尺度,匹配形状与大小变化的目标图像以提取目标位置;最后,对提取的目标位置进行α-β滤波,形成连续平滑的目标运动跟踪航迹,实现基于穿墙雷达成像的建筑物内运动人体稳定航迹跟踪。多输入多输出（MIMO）穿墙雷达实验结果显示,与传统Camshift和Meanshift算法相比,改进后算法的跟踪航迹误差分别降低了40.99%和43.09%,获得了更加准确和平滑的目标运动航迹。     

PGA算法解相位污染虚假目标问题的研究

电离层相位污染使天波超视距雷达(OTHR)回波信号的多普勒谱展宽,从而严重影响了雷达对目标的检测性能.相位梯度法(PGA)是现有的一种性能较好的解污染算法,但是当Bragg峰附近存在目标时,解污染后的回波谱会出现虚假目标,这严重影响了PGA算法的实际应用.本文从理论上分析了虚假目标的成因,提出采取分别利用正负Bragg峰进行PGA处理的方法,从而能有效地检测出这种情况下的真实目标.最后,本文给出了仿真结果,证明了该方法的有效性.     

基于多雷达的临近空间目标检测前跟踪算法

针对临近空间目标的低可探测性和多雷达采样周期与测量精度不一的问题,提出一种基于概率网格和多维Hough变换的多雷达检测前跟踪（ TDB）算法。利用概率网格将雷达测量数据概率化,通过多维Hough变换在多维空间建立初步候选航迹,利用基于不敏变换的空间融合方法得到目标数目及轨迹。仿真实验表明：该算法能够在密集杂波下实现弱小目标的有效检测。     

基于并行Boosting算法的雷达目标跟踪检测系统设计

目前的雷达目标跟踪检测系统跟踪路线与实际路线相差较大,泛化误差率高。基于并行Boosting算法设计了一种新的雷达目标跟踪检测系统,硬件内部引入数据多处理器,对收集的雷达位置数据集中处理,连接I/O接口,配置数据过滤器,将雷达位置信息数据的状态参数录入过滤器元件中。在软件部分,利用并行Boosting算法的内部学习融合方式调节不同的雷达目标追踪系统状态,通过信息处理、航迹分析、落脚点判断来整合相应的跟踪检测信息,构建检验方程式防止外来无关数据的侵扰,最终得到雷达目标跟踪数据操作状态,完成目标跟踪检测。实验结果表明,基于并行Boosting算法的雷达目标跟踪检测系统设定的检测路线与实际路线吻合度高达99.21%,泛化误差远远低于传统目标跟踪检测系统,实用性更强。     

基于结构多假设目标跟踪算法优化与仿真

研究雷达跟踪目标性能优化问题,传统多假设算法计算量大、实时性较差,无法应用于实际雷达装备。为解决上述问题,提出一种结构化分枝的多假设目标跟踪算法,同时提出限制最大航迹数量、删除负分航迹、低等级航迹处理、滑动窗口多维分配法、多扫分配法及交互多模型多假设跟踪算法等一系列改进方法,并通过计算机仿真证明改进后的结构化分枝的多假设目标跟踪算法比传统多假设算法及联合概率数据互联算法计算量更小,精度更高,并对改善当前舰载雷达跟踪性能,提高对目标的跟踪能力具有一定的指导意义。     

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。     

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.     

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.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.