基于高阶谱和倒谱的舰船噪声特征提取研究

研究舰船目标识别问题,舰船辐射噪声的特征提取一直是信号处理工程领域的难点.原因是海洋环境的复杂性和水声信道的特殊性,导致从复杂背景噪声中获取舰船信号特征显得比较困难.针对上述情况,提出了高阶谱和倒谱等多种类型的提取方法.根据舰船辐射噪声不同的特性,选择合适的提取方法,获取更多的线谱特征和抑制干扰噪声的特征信号.最后,采用高阶统计量的双谱、三谱、11/2维谱和倒谱对实测信号和仿真信号进行了特征提取,并指出各种提取方法所具有的优越性.实验结果表明特征提取方法是可行的,从而为目标识别提供有效的特征量.     

高阶统计量方法在谐波恢复中的应用

谐波恢复是信号处理中的重要问题,谐波恢复就是在噪声中分析组成信号的各次谐波.噪声分为加性噪声和乘性噪声,本文分析加性噪声和乘性噪声的特点,提出采用高阶统计量的方法抑制噪声,恢复谐波.通过四阶统计量的切片抑制乘性噪声,采用二阶累积量谱抑制加性噪声.仿真结果表明,本方法具有很好的抑制噪声效果.     

提高MFCC鲁棒性的方法

在噪声环境中,基于笔记本电脑录音的情况下,采用特征参数加窗的方法,以提高系统的噪声鲁棒性.在 Matlab 环境下,建立了基于高斯混合模型 (GMM) 的说话人辨认系统,并进行实验.通过对多种窗口的正识率比较,发现对美尔倒谱(MFCC)高阶参数的加窗提升,可以改善系统的鲁棒性.实验结果表明,采用加窗后的系统识别率得到了明显改善.     

基于频谱细化技术的精密旋转轴承音频信号故障检测方法研究

本文研究了基于复解析带通滤波器的复调制频谱细化方法（一种优化ZFFT算法）在精密旋转轴承音频信号故障检测上的应用;针对音频信号的特点,采用加汉宁窗三点卷积幅值校正法进行了误差校正.通过实验证明：该频谱细化技术可以得到高精度的音频信号频率细化谱线,为精密旋转轴承音频信号频谱的细化分析、特征提取、故障检测提供了一种简单有效的方法.     

改进的多窗谱MFCC在说话人确认中的应用

语音中存在加性噪声降低了MFCC参数的鲁棒性,使得说话人确认系统性能下降。多窗谱MFCC引入了多窗谱估计技术在增强 MFCC 特征的噪声鲁棒性上取得了一定效果,但改善的程度有限。为了使 MFCC 参数对噪声具有更强的鲁棒性,提出了一种改进的多窗谱 MFCC 提取算法。改进算法在多窗谱 MFCC 的基础上引入谱减思想,谱减法（Spectral Subtraction, SS）能够增强语音并降低噪音的干扰。因此,采用了Multitaper＋SS组合的改进算法融合了两者的优势,具备了更好的性能。仿真结果表明,当测试语音中含有加性噪声时,与多窗谱 MFCC提取算法相比,采用改进的多窗谱 MFCC 的说话人确认系统性能在等错误率 EER 和最小检测代价函数值minDCF两项评测指标上都取得了更好的结果。     

多载波CDMA子载波频率盲估计算法及其性能分析*

针对频谱感知和多载波CDMA信号解调的实际应用,根据多载波CDMA信号的循环平稳特性,提出了一种利用高阶循环累积量估计多载波CDMA信号子载波频率的方法。由于高阶循环累积量可以有效地抑制平稳噪声和非平稳高斯噪声,通过理论分析可以证明在上述噪声背景下,子载波采用BPSK调制的多载波CDMA信号的四阶循环累积量仅在循环频率为子载波频率处存在,可以通过检测此循环频率来实现子载波的估计。考虑到多载波CDMA信号发端可以采用不同的窗函数以降低频谱泄露,以常见的几种窗函数为例进行了算法仿真,发现本算法对窗函数的变化不     

相关乘性和加性高斯白噪声激励下周期势系统的随机共振

研究了外加周期信号作用下,相关高斯乘性和加性白噪声激励下周期势系统的随机共振.利用线性响应理论,计算了系统输出信号的功率谱密度、振幅、相位差.研究结果表明:当加性噪声强度和关联系数不变的情况下,通过调整乘性噪声强度可以出现随机共振;关联系数的正负以及大小对随机共振的影响较小.当乘性噪声强度较小时,输出信号的振幅和相位差曲线有一个单峰出现,即出现随机共振现象,能量从噪声向信号进行转化.随着噪声强度的增大,随机共振现象消失,噪声由增大系统的有序程度渐渐变为增大系统的无序程度.     

相位匹配噪声估计的高阶谱去噪方法

大多数去噪方法只能对高斯噪声或某一类有色噪声进行去噪处理.提出一种新的相位匹配噪声估计的高阶谱去噪方法.利用该方法既可以去除高斯噪声又可以去除非高斯噪声,通过高阶谱和相位匹配实时的逼近当前噪声,建立二次去除噪声方法,通过实验证明该方法能够非常明显的去除高斯与非高斯噪声,在无法分出噪声的种类情况下进行信号的去噪,取得非常好的去噪效果.     

采用PCNN的有噪特定人语音识别系统

在特定人语音识别系统中,噪声严重影响语音特征提取,并导致语音识别率明显下降。针对在噪声环境下语音识别率偏低的问题,通过谱减法去除语音信号噪声,并根据语音信号语谱图可视化的特点,运用脉冲耦合神经网络从语音信号的语谱图中提取熵序列作为特征参数进行语音识别。实验结果表明,该方法能较好地去除语音信号中的噪声,并能使在噪声环境下的特定人语音识别系统具有较好的识别效果。     

循环平稳算法的脉搏信号噪声评估指标

针对实际采集脉搏信号中各种噪声对信号质量的影响,提出一种循环平稳算法的脉搏信号噪声评估指标——质量因数,以评估脉搏信号受噪声影响程度。采用建模产生的脉搏信号、MIT-BIH数据库提供的脉搏信号与噪声信号叠加产生的试验数据进行验证。试验结果表明,质量因数可以准确地反映脉搏信号受噪声影响程度,脉搏信号信噪比越大,质量因数越大,则信号受噪声影响越小。该结果对正常、异常脉搏信号都适用。实际采集的较长脉搏信号,引入不同时宽的滑窗计算信号的时变质量因数,提取时变质量因数最大或较大的那段脉搏信号进行分析,减化了去除噪声等预处理过程,节省了计算量和时间。计算机完全可以自动计算质量因数,无需人工干预,为脉搏信号噪声的评估提供了新思路。     

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.     

基于QTE的蒙古文显示机制研究与实现

蒙古语言是中国蒙古族使用的通用语言,由于蒙古文区别于其他文字的书写方式和其自身变形机制等特点,在很多通用的文字处理引擎中都不被支持。在嵌入式产品开发与应用领域中Linux加QTE已经成为流行方式。该文给出了一种在QTE环境上实现基于标准Unicode的蒙古文点阵显示和变形算法, 并自定义了支持蒙古文的QTE组件,扩展了QTE功能,为在Linux加QTE方式的嵌入式体系结构中处理蒙古文提供了一种解决方法。     

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.     

基于AD9626的模拟信号采集存储卡设计

自然界的绝大部分信号都是以模拟的形式存在,因此模拟信号的采集转换存储在数字时代十分关键。文章讨论了在雷达信号处理领域基于AD9626的AD采集存储卡的设计原理、硬件结构和程序设计与芯片配置等问题,为今后相关领域的研究提供了可参考的方案。     

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     

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.     

A human-computer interface for non-computer specialists

The COM teleconferencing system was designed to be easy to use for both beginners and people with much computer experience. A number of design choices in organizing the human-computer interface were considered very carefully. These design problems are not unique for teleconferencing applications, but will appear in many other developments of human-computer interfaces for non-computer specialists. This report discusses naming conventions, menu format, user commands, help facility and the treatment of ‘type ahead’ from the users.