基于小波分析的涡街信号去噪算法在DSP中的实现

以数字信号处理器(DSP)为开发平台,将小波变换应用于涡街流量计,采用小波阈值去噪对涡街流量计信号进行处理,并提出了一种改进的小波阈值选取方法.实验结果表明该算法对涡街信号提取和噪声去除效果良好,可扩大量程范围,提高涡街流量计的测量精度.而且,DSP的应用又保证了实时性.     

用二重互相关算法扩展涡街流量计测量下限

介绍了采用二重互相关算法对强噪声干扰下的涡街信号进行滤波的原理和具体实现方法。对涡街流量计在测量下限时的信号与噪声情况进行了分析,将二次互相关滤波算法引入涡街信号的数字滤波过程中。给出了具体计算方法和各主要参数的取值规则。在实际使用中取得了良好的效果。     

高精度DSP涡街信号处理方案

针对涡街流量计信号较为微弱、易受噪声干扰等问题,以TMS320LF2407A DSP微处理器为核心,设计了高精度涡街信号处理系统.具体介绍了系统结构,并给出了详细的硬件设计方案.采用Mallat快速小波变换的算法实现涡街信号去噪,并概述了系统软件设计方法.仿真试验表明,该系统具有精度高、实时性强、性价比高等特点,有一定的工程实用价值.     

跟踪型数字滤波方法在涡街信号处理中的应用

涡街流量计广泛应用于流量测量领域。由于测量现场工况复杂,涡街流量信号常会掺杂着各种噪声干扰。尤其低流速时,涡街信号微弱,常被噪声淹没,如何提取真实的涡街信号是涡街信号处理的难点。提出一种新的算法来滤除噪声并提取涡街信号。该算法是基于涡街信号特征来设计的一种特殊滤波器,它能够实现涡街信号幅1／f2值衰减并且动态跟踪真实涡街信号频率。实验结果表明该算法能够自动识别涡街信号,滤除噪声。该算法严格控制了计算量,信号处理精度高,适合于工业现场应用。     

涡街流量计信号的高阶统计量特征

涡街信号的正确分析和有效处理是实现涡街流量计准确测量的先决条件之一.为研究涡街信号的非高斯性,提出了一种基于高阶统计量方法的涡街流量计信号分析的新方法.通过对涡街管壁差压信号的双谱分析,提取了不同流量下信号的非高斯特征.以信号的双谱幅度最大值作为特征参数,对不同流量下涡街信号偏离高斯分布的程度进行了定量估计.实验结果表明:涡街信号的非高斯性随着流量的增大而不断增加.这一研究结果为深入理解涡街现象、进一步优化涡街流量计的设计提供了有力的参考.     

基于EMD的幅值归一化涡街流量计信号处理

采用经验模态分解(EMD)方法对涡街信号中混杂的干扰噪声进行滤除,提取出真实的涡街信号。该方法首先将原始信号输至二阶低通滤波器进行幅值归一化,然后将处理后的信号经EMD算法分解成各噪声分量和真实涡街信号分量,进一步通过施密特阈值翻转法统计频率并且判别出真实的涡街信号所在的分量,从而达到提取涡街信号的目的。最后,通过对在线涡街流量信号进行仿真分析,验证了该数字信号处理方法的有效性。     

涡街流量传感器信号处理方法研究

设计一种基于变增益运算放大器和DSP数字信号处理单元的新型涡街流量计信号处理电路.利用DSP上集成的模拟数字转换电路(A/D)实时检测涡街流量计传感器输出信号的幅度和频率,采用数字模拟转换电路(D/A)对变增益运放进行控制,控制传感器输出信号幅度的相对稳定.针对涡街流量计输出信号的频率特性,设计基于DSP的FIR滤波算法,实现输出信号噪声的初步抑制,削弱原始信号中强噪声干扰.滤波后信号由DSP进行频率信息的精确计算以及流量的解算.实验结果表明,变增益运算放大电路有效解决了涡街流量计传感器输出信号幅度变化范围大而造成的放大电路复杂,分段放大信号幅度不连续等问题;采用DSP进行数字滤波及频率计算,实现了信号中噪声的抑制以及高精度流量解算.     

分层注水工艺中涡街流量计信号处理方法研究

在一体化分层注水工艺中,每个层段的流量都要精确测量,而其所需的流量计必须能长期置于井下,综合考虑选择涡街流量计作为智能分层注水工艺中的流量检测装置.但涡街流量计易于受到管道震动和流场扰动引起的噪声干扰,且注水管道在注水的过程中更容易产生干扰信号,尤其在小流量处很难分辨出传感器产生的频率信号.本文根据涡街流量计的特点,提出一种以硬件和Mallat算法相结合,处理低频段无法分辨的问题,并进行了试验验证和现场应用.实验结果表明,使用该种方法,能有效的减少噪声干扰,降低了流量计的下限,提高了精度.     

基于混沌理论的涡街微弱信号检测方法研究

针对涡街流量传感器在小口径、低流速下信号微弱,易被强噪声淹没而难于提取的特点,提出了利用Duffing振子检测微弱信号的方法.通过仿真对涡街信号中含有白噪声以及谐波干扰的情况进行分析,仿真和实验均表明:这种基于混沌理论的微弱信号检测方法对涡街信号中较强的白噪声以及频差较大的谐波干扰具有很好的免疫力,并且通过计算最大Lyapunov指数的波动频率能够准确估计出涡街有用信号频率,实现低流速下涡街微弱信号检测.     

MUSIC算法应用于SFGPR系统的信号处理

针对步进频率表面穿透雷达(SFGPR)得到的目标图像的分辨率和穿透深度被系统噪声和地下媒质损耗所限制这一问题,提出了应用多重信号分类(MUSIC)算法对SFGPR信号进行处理以得到目标深度信息.在实验中,采用单极化指数模型对SFGPR接收信号进行仿真,并考虑系统噪声和媒质损耗的影响,将MUSIC算法得到的目标图像与传统的快速傅立叶变换法(FFT)得到的目标图像进行了对比.仿真实验结果表明,在低功率噪声和低损耗媒质情况下,MUSIC算法比FFT算法可以提供更高的距离向分辨率和回波幅度.     

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.