基于高效自适应聚类算法的调制识别研究

提出了一种基于星座聚类的通信信号调制识别新方法.该方法将星座图形状作为调制识别的特征,运用聚类算法EAFCM(efficient adaptive fuzzy C-means)重建接受信号的星座图.基于模糊C-均值(FCM)聚类算法的自适应高效聚类算法EAFCM不仅克服了模糊C-均值聚类算法需要预先确定聚类参数c、对初始中心敏感等不足,而且具有良好的抗噪声性能.将该方法应用到对PSK/QAM信号的调制识别,实验结果表明该方法是实际有效的.     

OFDM多载波系统中子载波调制识别新方法

针对OFDM （Orthogonal Frequency Division Multiplexing）信号在非合作通信系统中,具有多种子载波调制类型且有些子载波调制类型难以被调制识别的问题,提出了一种对其子载波分类识别的新方法.此方法结合并改进了星座图聚类投影法和对数似然函数（Logarithmic Likelihood Function,LLF）算法,先对不同子载波调制信号进行星座图聚类投影从而识别出常规子载波调制类型,再进一步通过对数似然函数对常规子载波调制类型和偏移正交（Offset QAM,OQAM）调制类型进行分类识别,并在此基础上推导出子载波组的对数似然函数使其计算结果值更容易被判决门限分类.理论推导和计算机仿真结果表明这种方法能在信噪比高于15 dB的情况下完全识别子载波的调制方式.     

基于星座图匹配的OFDM子信道调制识别改进算法

文章针对OFDM信号侦察系统中已有的子信道调制识别方法难以满足实时性要求的问题,提出了一种基于星座图匹配的子信道调制识别改进算法,该方法采用标准信号星座图的幅度和相位分布构建识别函数,消除了抽取聚类法的调制阶数估计误差,提高了识别的正确率。通过理论分析和仿真试验,验证了该改进方法的有效性和可行性。     

基于特征提取的单——混信号调制识别研究

调制识别作为处理信号的基础,将围绕QPSK,8PSK,16QAM三种调制类型的单信号和同频同调制的混合信号展开研究.通过分析信号的高阶累积量特征和四次方谱线特征,对单信号和混合信号进行区分,并将信号的调制方式进行高效识别.针对信噪比和幅度比对识别算法性能的影响,进行了一系列的仿真试验,算法简单可行,对信号参数要求较低,具有工程应用前景.通过仿真实验发现,在信噪比大于5 dB时,该算法的准确识别率可达到95％.     

一种基于盲均衡的多径环境下调制识别算法

针对频率选择性多径衰落信道下MPSK和MQAM信号的调制分类问题,提出了一种基于盲均衡算法的自动识别算法.将接收到的码元星座图通过一组并行的自适应盲均衡器,当盲均衡器与星座图匹配时其代价函数收敛到最小.所以直接利用盲均衡的代价函数作为调制识别特征,当代价函数收敛后,将具有最小代价函数值的均衡器所对应的信号判为识别结果.仿真结果表明,该算法可以有效识别频率选择性多径衰落信道下的BPSK,QPSK,8PSK,16QAM,32QAM,64QAM信号.     

基于星座图的PSK、QAM信号联合识别算法应用

针对PSK、QAM信号的理论识别算法在实际应用系统中不能满足较高的识别精度这一问题,提出一种基于星座图的PSK、QAM信号联合识别算法.该算法首先对信号同步处理并恢复信号星座图,然后进行相位统计与星座图聚类,提取出星座图的中心点个数N、相位个数P以及最大半径与最小半径比R等特征参数,再构造评估函数C(N,R,P)以识别PSK、QAM信号的调制方式.实际应用表明,对码元数目大于800的PSK和QAM信号的识别准确率均高于94％;对信噪比为8.25 dB的860M数字集群TETRA信号的识别率高达94.12％.该算法流程清晰且不需要任何先验知识,非常适合实际应用,此方法已经在某公司的信号分析系统上得到了应用.     

改进环路结构的Gardner定时恢复算法

针对经典的Gardner定时恢复算法存在同步建立时间长、同步稳定性能差等问题，提出一种改进环路结构的Gardner定时同步恢复算法。首先，该算法选用立方插值和分段抛物线插值两种插值滤波器进行插值，得到两路最佳插值序列；其次，分别计算两路插值序列对应的定时误差并求加权平均值，得到环路的定时误差；最后，以两路最佳插值序列的加权平均值作为环路输出。针对正交相移键控（QPSK）、正交幅度调制（16QAM）两种调制信号进行了仿真验证。仿真结果表明，该改进算法作用于QPSK信号时同步稳定性更好，相比作用于16QAM信号，其环路开始同步时码元的位置对应的序列数明显减小；并且该算法在信噪比为-5 dB的情况下使QPSK信号星座图收敛半径为0.26左右，与类似锁频锁相（FPLL）的改进Gardner定时恢复算法相比收敛半径减小约0.08，该算法有效地缩短了同步建立的时间，提高了环路的稳定性，可广泛应用于高速解调系统。     

一种基于盲均衡的多径环境下调制识别算法

针对频率选择性多径衰落信道下MPSK和MQAM信号的调制分类问题,提出了一种基于盲均衡算法的自动识别算法。将接收到的码元星座图通过一组并行的自适应盲均衡器,当盲均衡器与星座图匹配时其代价函数收敛到最小。所以直接利用盲均衡的代价函数作为调制识别特征,当代价函数收敛后,将具有最小代价函数值的均衡器所对应的信号判为识别结果。仿真结果表明,该算法可以有效识别频率选择性多径衰落信道下的BPSK,QPSK,8PSK,16QAM,32QAM,64QAM信号。     

改进的DBSCAN算法在调制识别中的应用

提出了一种基于星座聚类的通信信号调制识别新方法。将基于密度思想的M-DBSCAN聚类算法运用于信号星座聚类,通过自适应更新聚类参数,利用其良好的抗噪声性能实现了较低信噪比高斯白噪环境下信号星座图的重构。将该方法应用到对PSK/QAM信号的调制识别,实验结果表明该方法是实际有效的。     

多注意力机制网络的调制识别算法

针对小尺度衰落信道下调制信号识别率低的问题，提出一种基于多注意力机制网络的调制识别算法。提取信号瞬时幅度/相位特征与同相/正交序列构建双通道输入方式，实现多尺度感受野。通过残差密集块提取双通道数据的频域特征，将特征向量融合后送入双向门控循环单元提取时域信息，引入改进卷积注意力机制模块和软注意力机制捕捉信号的关键特征，构建多注意力机制网络对BPSK、QPSK、8PSK、16PSK、PAM4、GMSK、CPFSK、16QAM、64QAM这9种信号进行调制识别。仿真结果表明，信噪比大于10 dB时，9种信号平均识别率达89.2%以上，与其它深度学习算法相比具有更高的识别率，验证了该算法的有效性。     

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.