加权融合法处理无序量测问题

针对集中式多传感器目标跟踪系统中存在的无序量测问题,基于协方差加权融合的思想,在融合估计误差协方差矩阵迹最小意义下,建立了基于最优融合的多步延迟无序量测更新算法。该算法先将无序量测配准到最新状态估计的时刻,将其与之进行协方差加权融合。为进行无序量测与各传感器量测噪声相关性的计算,引入了等效量测。通过理论分析和仿真实验说明该算法能有效处理无序量测多延迟问题,其性能接近最优且随延迟步数增加性能下降非常小,而且有与最优的数据缓存法相同的滤波精度,以及较小的额外存储量。     

粒子滤波的噪声相关下单步延迟无序量测更新算法

在目标跟踪系统中,因通信延迟等原因会出现传感器量测无序地到达融合中心的现象,将这些量测称为无序量测(OOSM).针对过程噪声、量测噪声相关的非线性系统中出现的无序量测问题,在现有算法基础上,提出了一种可处理单步延迟无序量测的新算法.在前向预测滤波框架下,对系统方程去相关化,并利用粒子滤波(PF)进行状态估计.仿真结果验证了算法的有效性.     

基于异质多传感器的网络分布数据融合的一种算法

针对多异质传感器数据融合能够实现信息互补,改善目标跟踪精度,提出了一种异质多传感器异步量测融合算法,即首先将量测方程线性化,再在砷合中心通过建立伪量测方程,得到同步的量测数据,然后利用噪声相关的伪序贯思想进行融合处理得到全局估计,与现有算法进行仿真比较,结果表明了该算法的有效性。     

毫米波/红外复合制导信息融合技术研究

研究红外复合制导问题,对于复合制导中的集中式融合,与共同的噪声环境等因素使得各传感器的量测误差之间存相关性,且相关程度未知,对得到的融合估计不是最优的.红外导引头测量存在不完全可观性,一般的分布式融合也难以实现.针对以上问题,提出了一种基于协方差交叉法的信息融合算法,在估计相关性未知时利用信息空间上的均值和协方差凸组合,通过寻找行列式的最小方差阵,融合各传感器的局部估计,可以得到不低于单个传感器估计的融合估计精度.进行量测相关数据,并通过UKF滤波仿真验证,证明算法的有效性.     

基于选择融合的任意步滞后无序量测滤波算法

在目标跟踪系统中,由于传感器具有不同的预处理时间与采样速率,以及信道固有的随机通信延迟,传感器量测数据可能出现无序到达融合中心的现象,即无序量测问题。在系统工作过程中,通常有多个无序量测相继或同时出现。为此,将多无序量测情形进行分类,基于选择融合提出任意步滞后无序量测滤波算法。利用基于对数似然比的假设检验筛选出需要处理的无序量测。在前向预测框架内,根据无序量测最优滤波过程,采用融入等价量测的信息滤波方法对目标状态估计与误差协方差矩阵进行更新。仿真结果验证了算法的精确性与有效性。     

含无序量测的多传感器信息融合算法研究

由于通信时间的延迟性,在多传感器系统中常常会出现无序量测情况.为提高估计的精度,系统须对无序量测进行处理,状态更新法是处理无序量测问题的一种有效方法.对于多传感器信息融合问题,给出了一种处理无序量测的状态估计更新算法.仿真计算表明该算法能有效的提高融合估计的精度.     

多传感器异步采样系统的顺序融合

针对现有基于伪量测的异步融合算法存在实时性差、融合时刻计算负荷大以及人为引入噪声相关等问 题,提出了一种新的基于采样点顺序离散化思想的顺序式异步融合算法．该算法首先将各个传感器的测量值在融合 中心的坐标系中和时钟下进行映射统一;然后,选取融合周期内各采样时刻对连续状态系统进行顺序离散化,从而 获得本周期内各采样点间的状态方程和相应的测量方程．最终,使用线性最小均方误差意义下最优的线性卡尔曼滤 波器实现本周期内异步采样量测的顺序滤波融合．仿真分析表明,该算法和基于伪量测的异步融合算法相比具有较 少的计算量、较好的实时性和较高的估计融合精度．     

快速边缘粒子滤波在无序量测问题中的应用

在目标跟踪系统中,因通信延迟会出现传感器量测无序到达融合中心的现象,由此产生无序量测(OOSM)融合问题。针对非线性条件下的OOSM问题,在现有算法的基础上,提出了基于快速边缘粒子滤波(FMPF)的处理算法。新算法在FMPF框架下,结合前向预测滤波思想来处理OOSM问题。将目标运动状态向量分为线性和非线性2个子向量,并分别采用相应的无序处理算法进行估计。算法可以处理单步延迟和多步延迟的情形下的无序问题。最后理论分析和仿真实验表明:新算法能有效处理OOSM问题,且降低了算法的计算复杂度,提高了算法实时性。     

多传感器测量中的方差估计

在多传感器加权融合算法中，各传感器的权值仅由传感器的测量方差决定。假设各传感器噪声为平稳过程且相互独立，本文提出了待测状态未知且时变情况下．多传感器测量方差的估计算法，并讨论了估计方差的统计特性，证明了估计的无偏性。针对工程中环境噪声的变化，进一步提出了加窗方差估计方法，并给出了窗口宽度和估计精度的关系．使算法能有效地跟踪环境噪声的变化。该算法无需设置依赖于环境的初始值，并给出了递推公式．使其可用于对多传感器测量方差的实时自适应估计。仿真结果直观地说明了估计方法的有效性。     

基于关系矩阵的主被动传感器统计融合算法

针对传感器对目标跟踪时观测噪声非高斯问题,提出了一种基于关系矩阵的主、被动传感器量测统计融合算法.采用方差加权距离处理传感器量测噪声非高斯问题,运用传感器综合融合度构建关系矩阵,并且在门限附近采用椭圆模糊处理技术,利用Perron-Frobenius定理计算量测融合过程中每个传感器的权重.仿真结果表明当传感器观测噪声具有非高斯特性时,基于关系矩阵的主被动传感器统计融合算法和传统的融合算法相比扰动较小,具有较好的稳定性,可用于改善跟踪系统的抗干扰能力.     

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.