一种改进的BP神经网络调制分类器

本文致力于基于神经网络的通信信号调制类型识别器设计研究.论文提出了一种改进的BP神经网络分类器,它采用7个特征参数,可以对CW、2FSK、4FSK、8FSK、2PSK、4PSK、8PSK、8QAM、16QAM、4ASK、8ASK共11种调制类型实现正确分类识别.论文讨论了方案设计,给出了仿真试验结果,并将其与其他神经网络分类器进行了性能比较.     

基于高阶累积量的数字调制信号识别方法

通信信号调制方式自动识别在信号检测、威胁分析、频谱监测等领域有着重要的地位,是非合作通信关注的关键技术.针对单一累积量调制信号识别有限且识别率低等问题,利用信号的二、四、六阶累积量特征所构造的矢量集,实现了MASK、MPSK、MFSK、MQAM四类信号的类间识别,以及2ASK、4ASK、8ASK,2PSK、4PSK、8PSK,2FSK、4FSK、8FSK,4QAM、16QAM、64QAM的类内识别.在Matlab环境下进行了仿真实验,实验结果表明,该方法在信噪比大于5 dB时可以达到90％以上的识别率.     

一种小波特征与深度神经网络结合的信号制式识别算法

针对当前通信信号的制式识别算法在低信噪比情况下识别不准确的问题,提出一种新的小波特征与改进的深度神经网络结合(WL-DNN)的识别算法。该算法将生成的10种{2ASK、4ASK、2PSK、4PSK、2FSK、4FSK、OFDM、16QAM、AM、FM}含有高斯白噪声的通信信号,用小波分解重构算法提取出一类新的小波特征参数。本文测试了含有多层隐含层的改进BP神经网络作为分类器,利用弹性反向传播算法训练神经网络的参数,确定神经网络的最优超参数。仿真结果表明:在信噪比低至0 dB的情况下,单个调制信号最低识别率超过95%,平均识别率超过98%,大幅提高了制式识别在低信噪比下的识别率,由此表明了该算法的有效性和正确性。     

RFID调制方式测试方法的研究

随着RFID技术的发展,测试方法已经成为制约RFID发展的关键技术。本文提出了一种新的基于软件无线电的RFID调制方式测试方法。它采用4个特征参数和BP神经网络作为分类器,可以对2ASK、4ASK、2FSK、4FSK和BPSK共5种调制类型实现正确分类识别。讨论了方案设计,给出了仿真实验结果。仿真结果表明该方法具有较好的适应性、实时性和准确性。     

软件无线电中调制信号的神经网络识别方法

对接收信号的调制类型进行自动识别,在软件无线电这类多模式通信系统中非常重要。本文从调制信号幅度、相位、频率及功率谱等特性中提取特征参数,用于识别2ASK、4ASK、2FSK、4FSK、BPSK、QPSK、16QAM、MSK等信号。仿真结果表明采用神经网络识别算法,不仅可提高识别的智能化,而且能提高正确识别率。     

软件无线电中调制信号的神经网络识别方法

对接收信号的调制类型进行自动识别,在软件无线电这类多模式通信系统中非常重要.本文从调制信号幅度、相位、频率及功率谱等特性中提取特征参数,用于识别2ASK、4ASK、2FSK、4FSK、BPSK、QPSK、16QAM、MSK等信号.仿真结果表明采用神经网络识别算法,不仅可提高识别的智能化,而且能提高正确识别率.     

基于小波和高阶累积量的数字调制识别算法

利用基于高阶累积量的数字调制识别算法对数字调制信号进行分类识别时,六阶及六阶以上累积量的计算过于复杂,且多进制频移键控(MFSK)与8PSK信号各阶累积量的值均相等,直接计算无法识别。针对此问题,提出了一种基于小波和高阶累积量相结合的分类算法,先对MFSK与8PSK信号进行小波变换,再利用四阶累积量进行识别。实验证明,利用该算法所提取的特征参数能有效抑制高斯白噪声,除了识别2ASK/BPSK,4ASK,2FSK,4FSK,QPSK,8PSK信号外,还可识别16QAM,并且计算量小,易于实现。当信噪比大于等于3dB时,总体识别率达到96%。与已有算法相比,仿真结果证明了该算法的优越性。     

基于卷积神经网络的通信信号调制识别研究

针对传统人工提取专家特征来进行通信信号识别的方法存在局限性大、低信噪比下准确率低的问题,提出一种复基带信号与卷积神经网络自动调制识别相结合的新方法。该方法将接收到的信号进行预处理,得到包含同相分量和正交分量的复基带信号,该信号作为输入卷积神经网络模型的数据集,通过多次训练调整模型结构以及卷积核、步长、特征图和激活函数等超参数,利用训练好的模型对通信信号进行特征提取和识别。实现了对2FSK、4FSK、BPSK、8PSK、QPSK、QAM16和QAM64 七种数字通信信号类型的识别分类。实验结果表明,当信噪比为0dB时,七种信号的平均识别准确率已达94.61%,验证了算法是有效的且在低信噪比条件下有较高的准确率。     

用MATLAB模拟实现数字信号的调制与频谱分析

运用MATLAB语言模拟实现了数字信号的ASK、FSK、PSK调制与频谱分析.     

基于高阶累积量的数字调制信号识别

利用接收信号的高阶累积量为特征参数,实现了对多种常用数字调制信号(2ASK/BPSK,4ASK,QPSK,8PSK,2FSK,4FSK)的分类识别.由于信号六阶以上累积量的计算过于复杂,在选取特征参数方面主要利用信号的二、四阶累积量.8PSK与MFSK信号的二、四、六阶累积量的值均相同,直接计算无法区别.针对这一问题,首先对8PSK和MFSK信号求微分再利用四阶累积量来进行识别.实验证明,所提取的特征能够有效抑制高斯白噪声的影响,并且计算简单,便于实现.当信噪比为8 dB时,识别率基本达到100%.与已有算法的比较,结果证明了该算法的优越性.     

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.