基于单步模型算法的PMSM控制策略

分析了永磁同步电机(PMSM)矢量控制系统的工作原理,针对传统PI控制器调节时间长、对电机参数依赖度高的缺点,采用了单步模型算法控制策略。设计了基于单步模型算法的永磁同步电机矢量控制系统,并进行了仿真分析。仿真结果表明,单步模型算法控制策略具有不过分依赖电机数学模型、能较好地抑制各种不确定性干扰等优点,系统在动态过程中有较小的超调,且对于负载扰动具有较强的鲁棒性。     

液压伺服位置系统模型参考模糊自适应PID控制器的设计

针对液压伺服位置系统被控对象，提出了用模型参考模糊自适应机构对PID控制器比例系数进行在线调节，以减小液压伺服位置系统中参数摄动等引起的超调和振荡；同时为简化控制器，提出了用变积分系数的方法来消除负载扰动给系统带来的稳态误差。仿真研究结果表明，具有模糊自适应和变积分系数的控制器使控制系统既有较高的稳态精度，同时也使系统具有较快的动态响应，整个系统具有很好的鲁棒性。     

船舶无刷发电机励磁控制系统的数字仿真

在船舶发电机性能优化控制问题的研究中,无刷发电机励磁控制系统能改善船舶电力系统的电压稳定性.由于输电线路受负载扰动,影响电网的稳定性.为了提高电网性能,在各单元数学模型的基础上进行分块数字建模,采用船舶常用的相复励与PID结合的控制策略,用控制器为核心的闭环励磁控制模型建立仿真系统.根据实际系统设置参数,仿真扰动和故障工况.仿真结果反映了船舶无刷发电机励磁控制系统的动态性能和故障特征,证明了仿真模型和方法的正确性,可用于船舶励磁控制系统的设计调试和性能评估.     

雷达天线控制系统频域辨识与仿真方法研究

雷达天线控制系统仿真是雷达系统目标跟踪动态仿真中一个重要环节;为解决雷达天线控制系统仿真中滞后误差大、动态效果差等问题,依据某雷达天线控制系统性能实际测试结果,以典型系统模型作为研究对象,利用频域最小二乘法完成模型参数辨识,建立系统模型,并对辨识模型进行验证;在此基础上,采用基于时域的增广矩阵法对系统进行了数字快速仿真分析;结果表明,辨识模型满足精度,且增广矩阵法能够有效快速地完成系统数字仿真,对天线控制系统建模以及快速动态仿真研究具有一定的参考价值.     

基于状态方程模型的双容水箱实时仿真

针对双容水箱闭环控制系统,通过机理分析方法建立了被控对象和控制通道的状态方程数学模型,通过差分方法对模型进行数字化,不必进行非线性处理,直接按时序进行递推求解,从而有效简化了模型的数学处理过程,并利用组态软件脚本语言,分别编制了被控制对象和控制通道各单元仿真程序,实现了双容水箱液位控制系统的仿真。仿真系统具有实时性和在线性特点,操作过程与实际生产操控形式完全相同,可连续对干扰和设定值变化进行在线仿真,仿真系统对于实际控制系统PID参数整定以及生产操作人员的培训具有重要的参考价值。     

非线性系统的特征建模与控制方法

本文针对一大批工程实际中经常遇到的非线性系统，为设计低阶控制器，提出了非线性系统的低阶变参数特征模型的原理和方法，论证了所建特征模型与实际对象的等价性。文章介绍了如何根据非线性特征模型设计控制器的基本原则与步骤，文章通过某真空环境温度控制系统的仿真，进一步阐明了这种非线性系统特征建模及其控制的方法，最后给出了利用特征模型进行自适应控制的仿真与实际工程应用的结果。     

基于误差阈值通信逻辑的输出反馈网络控制系统设计

针对网络控制系统被控对象状态无法直接测量的情况,设计了状态观测器,给出了一种基于误差阈值的确定通信逻辑,应用于基于模型的网络控制系统中,提出了具有确定通信逻辑的网络控制系统结构,建立了系统模型,仿真数例表明加入确定通信逻辑后,在保持系统稳定的情况下,数据发送的次数明显减少,有效地减轻了网络负载。     

无刷直流电机伺服系统的仿真实现

本文在介绍无刷直流电机伺服控制系统仿真模型的基础上,讨论了在Matlab/Simulink仿真环境下该系统速度调节及其换相逻辑的实现,最后给出了一个实际系统的仿真实验结果,为实际电机控制系统的设计和调试提供了新的思路.     

基于逆系统原理的感应电动机滑模速度控制

针对目前逆系统原理应用于感应电动机调速系统中时往往忽略参数不确定性的问题,从感应电动机的非线性模型出发,采用逆系统理论建立了转子电阻与负载参数不确定的感应电动机伪线性控制系统模型;提出了一种采用变指数趋近律实现的防抖动自适应滑模变结构控制方法,并将该控制方法应用于感应电动机伪线性控制系统中。仿真结果表明,基于逆系统原理的感应电动机滑模速度控制方法能够有效抑制系统参数的不确定性,提高系统的稳定性和控制精度。     

火电厂主汽温控制系统的QFT设计与仿真

火电厂主汽温控制系统具有大惯性、大延迟和时变等特性,采用常规控制方法的主汽温控系统难以获得满意的控制效果.定量反馈理论是目前鲁棒控制领域中具有较强工程应用价值的一种设计方法.首先将火电厂主汽温控制系统对象简化成为具有三参数变动的不确定模型,应用QFT的基本原理,设计了边界稳定的鲁棒控制器,保证了稳态精度5%和过渡过程时间小于1秒.仿真结果表明它能适应对象参数的变化,具有较强的鲁棒性和自适应能力.     

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.