水轮发电机组的模块化建模与仿真

关于开发建立实时精确的水轮发电机仿真系统,由于水轮发电机组由同步发电机、励磁系统、水轮机及其调速系统构成,系统的数学模型存在强非线性,传统上常采用牛顿法联立求解方程组仿真效果差.为解决上述问题,提出了面向水轮发电机组各物理子系统的模块化仿真模型,采用分割求解法建立了同步发电机、励磁系统、水轮机及其调速系统各物理子系统的数学模型,用隐式梯形积分法建立了模型,形成了水轮发电机组模型库.组成的仿真系统不仅可达到足够的计算精度及计算速度,而且有效简化了水轮发电机组模型的开发及维护工作量,适用于水轮发电机组的快速电磁暂态和中长期的机电暂态过程研究,可用于各型水电站动态全过程仿真.结果证明系统运行的精度和速度的有效性,为研究提供参考.     

倍频积分测频电路的设计

一、前言水轮发电机组的频率测量的目的,就是在于控制水轮发电机的转速n,即发电机的频率f,它的关系式为 f=(p/60)n (1)式(1)中P为发电机极对数若用相对值x表示 x=f/f_r=n/n_r (2)n_r、f_r分别为水轮发电机组的额定转速和发电机的额定频率,通常维持在国家规定x=±0.2％的范围之内。以保证机组生产电能的质量。目前水轮发电机组测频电路的类型很多,本文仅就倍频积分测频电路结合工程设计,分述如下。     

发电机电气制动方法及其应用研究

利用Matlab对水轮发电机不同别动方法进行了仿真,计算出了不同水轮发电机组在不同的投入转速和不同的制动电流下的制动时间,为水轮发电机电气制动方案的设计以及选择最佳的制动参数提供了重要的依据.     

一种改进粒子群算法在水轮机控制中的应用

关于水轮发电机控制系统优化问题,水轮发电机组的控制技术对于水轮发电机组稳定工作非常重要。针对保证供电质量,改善调节系统的非线性时滞特性,利用具有局部搜索能力的粒子群算法对水轮发电机组进行模糊PID控制可以确保控制的稳定性。首先,根据水轮发电机组的控制原理和模糊PID控制器的基本结构,提出具有局部搜索能力的改进粒子群算法,利用模糊PID控制器以及采用了改进粒子群算法的模糊PID控制器,用MATLAB软件对水轮发电机组进行优化控制仿真,仿真结果表明采用改进粒子群算法的模糊PID控制器具有最优的控制效果。     

广东研制成功新型发电机达目内先进水平

日前，一项旨在节省投资、提高水轮发电机发电效率和使用寿命的“双转轮组合卧式水轮发电机组”在广东省梅州市研制成功，并通过水利专家鉴定。专家认为，该项技术总体达国内先进水平。     

蠕动探测器在水电厂的应用

湖北省清江隔河岩水电厂装设4台单机容量为30万kw的混流式水轮发电机组.考虑到隔河岩水电厂水头高,进口的水轮机效率也很高,在导水叶关闭不严的情况下,全停机组可能会发生缓慢转动,即蠕动.机组蠕动对水轮发电机推力轴承来讲是十分有害的.为了保护机组,加强对全停机组的监视,在隔河岩水电厂水轮发电机组安装了蠕动探测器.     

传感器及组态软件技术在水轮发电机组摆度和振动监测中的实际与教学应用

水轮发电机组的长期振动将导致机组部件材料疲劳严重时损坏机组,影响水轮发电机组安全运行和发电效益,而水轮发电机组故障均为渐变型故障,因此对水轮发电机组摆度和振动的监测就显得非常有必要.利用传感器及组态软件技术组成的水轮发电机组摆度和振动监测系统不仅可以有效地避免水轮发电机组意外事故,节约维修费用,对水轮发电机组具有十分重...     

水轮发电机组的模型参考自适应控制

水轮发电机组是一个变参数的非最小相位环节,并且只有部分状态可直接量测.本文导 出了适用于这类系统的一种模型参考自适应控制系统.由于引入自适应控制,使水轮发电机 组的参数变化时,系统的稳定性和频率跟踪性能得到改善.     

基于RBF-PID的水轮发电机组控制系统

研究水轮发电机组稳定性控制优化问题,水轮发电机组是一个非线性、时变的复杂控制系统,很难建立精确模型。采用常规PID控制策略难以较高的控制精度,超调量大。为提高水轮发电机组控制精度,将自学习较强的RBF神经网络与常规PID相结合,提出一种基于RBF-PID组合的水轮发电机组控制算法。采用RBF神经网络对水轮发电机组控制系统的Jacobian矩阵信息进行在线辨识,实现RBF-PID参数在线自整定。仿真结果表明:RBF-PID组合控制器不仅提高控制系统的精度,而且超调量小、抗扰动能力强,能够很好实现水轮发电机组的稳定性优化控制。     

水轮发电机故障诊断的仿真研究

研究水轮发电机故障诊断问题,引起水轮发电机故障原因相当多,传统故障诊断方法无法消除故障特征之间的重复信息,特征数量多,导致故障诊断效率和准确率低。为了提高水轮发电机故障诊断准确率,提出了一种基于粗糙集与最小二乘支持向量机(LSSVM)的水轮发电机故障诊断方法。首先采用粗糙集对水轮发电机故障特征进行约简,消除特征之间的重复信息,然后采用组选择算法对特征集进行二次约简,选择比较重要故障特征值,最后采LSSVM对水轮发电机数据集进行训练和故障诊断。仿真结果表明,粗糙集与LSSVM相结合的方法提高了水轮发电机的故障诊断准确率,更适合于水轮发电机故障的实时和在线性诊断。     

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.