基于DSP的电动执行机构相序检测及缺相保护方法

电动执行机构的相序检测及缺相保护缺失,易造成阀门和执行机构损坏,给出一种基于DSP的智能电动执行机构相序检测和缺相保护的实现方法.通过分析三相相电压和三相线电压的相位和相序的动态关系,设计了三相电源的整流、隔离、整形处理的检测电路,给出了基于DSP的相序检测和缺相保护的程序控制流程.最后对该方法在研制的智能型电动执行机构中的使用性能进行了检测,结果表明该设计方案运行稳定,系统的相序和缺相状态判定时间小于100 ms.     

用漏电保护开关改制电机缺相保护器

关于电机缺相保护器,市售产品和资料介绍的已很多。笔者介绍一种由家用漏电保护开关改制,针对三相熔丝故障的缺相保护器电路供参考。由于漏电开关价格便宜(仅二十多元一只),取材方便(电料店皆有售),且具备制作缺相保护器的几乎全部元件,仅需增加三只电阻便可方便地改制,而市售产品价格总在百元以上,因而只有一定的实用价值。     

安全缺相保护器

贵刊曾介绍过一些三相电机缺相保护装置,各具千秋,但大部分只适用于动力线的缺相保护。实际上,电机缺相的原因是很多的,如交流接触器Kl的相触点组K_(la)～K_(lc)接触不良、三相闸刀S接触不良或接线不良、电机内部断相、动力线缺相等等。除动力线缺相之外,对其它诸原因引起的缺相,贵刊所介绍的缺相保护器大都无能为力。本文介绍的“安     

漫谈电动机缺相保护

本刊95年第5期刊登了安刚同志的《对“简单经济的缺相保护电路”的再改进》后,陆续收到了辽宁王金荣、山东刘国起、贵州柯世壁、河南赵兴涛、浙江裘正伟、湖南邱亚新等同志来稿指出文中的保护电路仅在空载时起作用,接上电机不能实现缺相保护。有的同志通过实验测试,有的进行理论分析,有的提供了经过实践验证的缺相保护电路。为纠正错误,这里发表柯世壁同志的“漫谈电动机缺相保护”一文。由于篇幅所限,其他几位同志的来稿不能发表,敬请鉴谅。对读者关心爱护本刊,积极参与的精神,我们表示衷心的感谢。     

缺相保护控制器的制作

在2005年9期《电子制作》第13页刊登了一篇实物测绘并有波形分析的缺相保护电路文章,原理分析透彻,可信度高。在此基础上笔者制作了有、无外接控制电压2种缺相保护控制器,效果很好。     

再议电机缺相保护

《电子制作》98年第7期的《对“电动机缺相保护器”可靠性的探讨》一文指出了《续谈电动机缺相保护制作》所介绍的保护器在电动机正常运行中缺相会失灵,这是完全符合实际情况的。《电子制作》98年第5期的《简单可靠的电机缺相保护装置》文中的保护装置也与上述保护器大同小异,在电机运行中缺相时也会失灵。     

集成电路在三相交流电动机缺相运行中的应用

介绍了一种新的避免三相交流电动机缺相运行的保护控制装置。它主要由集成元件组成，具有体积小、重量轻、灵敏度高的优点。     

这种“安全缺相保护器”不起保护作用

我看了贵刊96年11期张义方同志《安全缺相保护器》一文,认为不能起到缺相保护作用。按照张义方同志介绍的缺相保护器(见图96年11期),在不缺相时,因为流经La、Lb、Lc三线圈的电流相位差为120°,它们所产生的磁场向量和为零,所以在Ld上将不产生感生电动势;当缺一相时(假设缺La),这样余下两相(Lb和Lc)产生的磁场向量和也为零,同样在Ld上不产生感生电动势。形象地说,当不缺相时,La、Lb、Lc中电流方向必定是两相方向相     

对“简单经济的缺相保护电路”的再改进

看了《电子制作》94年第6期的“对简单经济的缺相保护电路的改进”一文后,感到原文有一些不足之处:原文图1的保护电路不够可靠,对于交流接触器触点及接头不良引起的缺相无法保护。图2的电路太复杂,且另需一组电源。为此,笔者特设计了如附图所示的保护电路,     

“用两只继电器做成缺相保护器”欠妥

99年6期发表的《用两只继电器做成缺相保护器》一文有欠妥之处,如果是电动机起动前缺相,此方法有效,起动后缺相将会失灵。分析方法见98年7期、12期。实践证明,电机缺相往往是运转中保险烧断所引起。我对此图改动一下,认为便能达到保护作用,图中,电动机星点接地,C、ZJ1、ZJ2使用线圈电压为220V的继电器,当电动机运转时,任意一相缺相时,对     

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.