煤矿井下电磁无线随钻测量信号滤波研究

针对采用自适应滤波最小均方算法和递推最小二乘算法提取煤矿井下电磁无线随钻测量(EMMWD)信号存在收敛速度慢与运算时间长等问题,提出了一种稳定快速横向递归最小二乘(SFT-RLS)算法,用于自适应滤除井下非稳态电气干扰与工频及其2倍频、3倍频干扰,实时提取微弱EM-MWD信号。该算法基于RLS算法,利用4个并行滤波器结构可降低运算时间,并利用加权最小二乘误差进行反馈以提高稳定性。仿真试验结果表明,SFT-RLS算法可实现对采样率为1kHz的EM-MWD信号进行自适应滤波和自适应陷波,平均每次迭代运行时间小于156.98μs,实现了快速稳定收敛运算与实时自适应滤波;SFTRLS算法自适应滤波可抑制信号与干扰比为-115dB的非稳态电气干扰;SFT-RLS算法自适应陷波可实时滤除工频及其2倍频、3倍频干扰,有效提取频率为6.25Hz的时间脉冲位置调制的EM-MWD信号波形,为正确解码EM-MWD信号提供了可靠数据。     

相位量化DRFM欺骗干扰的自适应检测

为了从环境中检测出相位量化数字射频存储器(Digital radio frequency memory, DRFM)欺骗干扰的存在,本文设计了一种能够在均匀环境中检测出噪声、干扰或回波信号的自适应检测器。检测过程分为两步：先由基于广义 似然比检测(Generalized likelihood ratio test,GLRT)的自适应匹配滤波(Adaptive mat ched filter,AMF)检测器完成噪声和“信号”（滤波后的回波信号或干扰）的检测;再从回波信号和干扰导引矢量间的差异性出发重新设计检测器,以甄别回波信号或干扰。最后, 通过理论推导和蒙特卡洛试验对检测器的性能进行分析和评估,并与透视检测器进行比较。 仿真结果表明,在低相位量化位数和高信噪比的条件下,所设计的检测器能够正确检测出干 扰信号的存在。     

自适应极化滤波的抗干扰性能研究

针对极化域这一崭新的电子对抗(ECM)领域,研究了基于卡尔曼滤波的自适应极化滤波技术.该技术在雷达信号间歇期进行干扰极化状态的估计,在雷达信号存续期进行自适应极化滤波.理论分析和仿真结果均表明该技术具有极高的极化估计精度,在抑制干扰的同时,可提高信干比约40 dB.     

基于AR-SRCKF的SINS/GPS深耦合抗转发式干扰研究

转发式干扰转发真实的卫星信号导致伪距信息错误,能不被察觉地使捷联惯导系统（SINS）和全球定位系统（GPS）的深耦合组合导航解算错误。根据深耦合中信号处理的特点,将错误的伪距视为粗差,提出一种基于自适应抗差平方根容积卡尔曼滤波（AR-SRCKF）的融合算法。该方法采用自适应抗差滤波作为算法的框架,提高系统对转发式干扰的鲁棒性,同时为了避免线性化误差造成滤波性能的下降,采用平方根容积卡尔曼滤波（SRCKF）解决非线性滤波问题以及确保协方差阵的对称性和半正定性。最后,深耦合系统下的仿真分析验证了其对转发式干扰具有良好的鲁棒性。     

DS-MSK数字化接收机的自适应抗干扰滤波仿真

为在直接序列扩频-最小频移键控（DS-MSK）数字化接收机中设计和实现抗干扰模块,分析了过采样条件下DS-MSK信号的最小均方误差（MMSE）最优滤波问题,考虑到最优滤波难于直接实现,讨论了用自适应抗干扰滤波（AAJF）来逼近MMSE最优滤波性能.传统的非线性滤波往往假设干扰估计误差功率远小于码片功率,这一条件在工程实现中很难满足,相应的抗干扰性能难以达到.为此,对非线性滤波加以改进,提出了部分解扩非线性滤波（PDNF）.蒙特卡罗仿真表明：PDNF滤波性能明显优于传统非线性滤波,接近MMSE最优滤波性能.     

自适应滤波的研究新方向

概述了自适应滤波的研究进展,回顾了时域和变换域自适应滤液方法,并引出了基于离散小波变换（ＤＷＴ）的自适应滤波。变换城自适应滤波大大改善了时域自适应滤波的速率,而小波变换由于具有多分辨和时频局部化特性,在时变信号和快速变化的信号自适应滤波方面个有广阔的应用前景,是未来自适应滤波发展的方向。     

一种基于经验模态分解与瓦片编码的自适应轴承故障诊断方法

针对传统依赖经验参数的轴承故障诊断方法在不同噪声等级场景下准确率不高的问题,文章提出一种基于经验模态分解与瓦片编码的自适应轴承故障诊断方法。首先,其引入成熟的自适应分解算法——经验模态分解（empirical mode decomposition,EMD）对轴承振动信号进行分解,再根据一定规则选取相应的分量作为有效信号,结合谱平均对信号进一步去噪,实现轴承振动信号的自适应滤波;其次,采用基于瓦片编码（tile coding）的谱编码对滤波后信号进行特征提取,将编码结果作为特征输入K近邻（K-nearest neighbors,KNN）分类器;最后,在进行实例验证时,文章构建一个不同程度噪声的验证数据集,将所提出的自适应方法与经典的基于自适应滤波的故障诊断方法进行比较。结果显示,在信噪比高于-10 dB的情况下,该方法的诊断准确率达到了90%以上,优于其他方法的。     

自适应噪声抵消技术的应用研究与仿真

从噪声中分离有用信号是信号处理领域一个非常重要的课题.传统的滤波方法对于淹没于强干扰噪声背景下的有用信号提取已经不适用,而自适应滤波技术以其原理清楚,可实现性强而具有很强的应用价值.随着自适应技术的发展,自适应本舰噪声抵消技术已成为舰载声纳的信号处理技术中重要的研究课题之一.通过对自适应噪声抵消器原理的研究,结合舰载声纳信噪模型分析,重点研究利用自适应噪声抵消技术从舰载声呐在本舰强噪声干扰背景下提取有用信号的技术,并运用MATLAB进行了仿真试验.仿真结果表明自适应噪声抵消技术可以有效抵消本舰发出的强噪声,从而抑制本舰噪声对舰载声呐的干扰.     

手术机器臂前端控制器双重滤波的噪声抑制

医生在机械臂的辅助下手术时常会因为末端抖动而导致手术不稳定.小波滤波和自适应滤波相结合的方式对前端控制器信号进行滤波,由于自适应滤波器具有可以实时滤波的特性,采用自适应滤波器对含有不同方差的高斯白噪声的正弦信号模拟的信号进行滤波,均方根误差和误差率作为评价标准.实验结果表明,使用小波滤波预滤波后的信号通过自适应滤波可以实时有效地滤除前端控制器中的噪声,对噪声信号进行抑制.     

基于自适应陷波的干扰抵消技术分析

基于自适应滤波技术,从中频和射频两方面分析了干扰抵消技术的基本原理,给出了仿真结果,验证了算法的有效性,并对射频和中频两种干扰抵消技术进行了比较。自适应滤波技术在语音信号处理、噪声抵消,系统模型识别和医学信号处理等领域已得到大量应用,它是以最小均方误差为准则的最佳滤波器。在滤波过程中,它能自适应地调整滤波系数,其计算量小,算法简单,尤其适合于对实时信号要求较高的场合。     

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.