减少220 kV主变压器故障冲击技术措施

由于220 kV主变压器中压侧所配的过流保护需要与下级110 kV主变压器保护相配合,导致主变高、中压侧过流保护动作时间整定过长。在110 kV系统发生短路故障时,如果相关保护、开关不能正确动作,则主变压器将承受大电流、长时间的冲击,极有可能损伤变压器。     

基于DSP和CPLD的电能参数监测系统设计

电能质量监测技术是当前电力系统领域的研究热点.针对电网三相电压及电流信号的采集与处理,设计了电能质量检测装置的数据采集系统,系统采用DSP作为核心处理器,完成了多通道数据采集、数据处理、键盘显示、复杂可编程逻辑控制器CPLD与单片机外围接口等关键模块的软硬件设计.在硬件方面,重点介绍以DSP和CPLD为核心的电力参数检测电路以及CPLD和锁相环组成硬件同步采样电路;在软件方面进行了相关软件算法设计,同时介绍了电力参数检测的主程序.实验表明,系统具有响应速度快、精度高、实时性好的优点.     

基于物联网技术的电力变压器动态运检系统设计

在加强智能电网的建设中，电力变压器是重要的一环，其运检工作是确保整个变电站能够正常运行的根本。为实现更加智能、科学的动态运检，设计基于物联网技术的电力变压器动态运检系统。基于物联网技术设计射频识别模块，由射频标签、编程器等构成，实现电力变压器设备的自动化识别与系统的双向非接触数据通信功能。在线监测模块主要通过变压器智能组件柜实现电力变压器的在线监测。在巡检模块的设计中，为实现动态巡检，设计悬挂式巡检机器人，为其配置吊挂轨道，轨道经过站内所有电力变压器设备，使轨道尽量远离人员和柜体设备，实现电力变压器的巡检。在检修模块中，结合可拓学与粗糙集理论设计故障诊断算法，实施电力变压器的故障诊断。系统测试结果表明，对于主变故障与站用变故障，系统的故障诊断误差率均较低；在5台主变的巡检中，系统仅使用了90分钟左右的时间；在8台站用变的巡检中，系统仅使用了113分钟左右的时间；系统的故障定位准确率较高。     

基于CPLD的航姿数据采集器设计

提出了一种针对微小型无人直升机航姿测量系统的航姿数据采集方法,设计了以复杂可缟程逻辑器件(CPLD)为核心的航姿数据采集器.该采集器由CPLD和ADC器件组成,通过SPI模块与ADC控制模块来实现对数据的采集,通过数据FIFO和通讯模块完成与航姿计算机的数据交换.     

220 kV输变电一次系统设计

在众多类型的变电站中,220 kV变电站对于我国电力行业的发展影响较大,因此如何保证220 kV变电站运行稳定性强、电能转化效率高,是220 kV降压变电站设计的关键所在。从220 kV变电站的负荷角度进行设计,并且利用计算后的负荷容量结果作为主变压器的选择依据。选择能够与三个等级电压相互匹配的主接线方式,使用标幺值法对各个电压等级进行短路计算,求出三相短路电流。     

变压器多维度综合监测边缘计算装置

1目标和概述 电力设备的安全运行与电气设备的有效检测密切相关,因此如何建立电气设备状态监测系统十分重要.对电气设备运行状态进行实时评估和诊断,能够大幅度提高电网运行的可靠性.电力变压器作为电力系统中的重要组成部分,针对电力变压器的状态感知显得尤为重要.通过调研2020年全国66kV及以上两万多台变压器的事故率、故障跳闸...     

多主变并列运行变电站中性点运行方式的优选方法

介绍220kV主变中性点运行方式与零序保护、间隙保护的关系,并从110kV系统发生接地故障的角度进行分析,提出220kV变电站主变中性点运行方式的优选方法。     

变压器局放监测与改进BP神经网络预测模型研究

采用传感系统监测变压器局部放电的变化情况,选取高频电流信号和超声波信号作为变压器局部放电的监测参量,利用改进逆传播(BP)神经网络算法对变压器局部放电量进行建模分析.以D9—QY—40000/220型电力变压器(220 kV变压器)为例进行实例研究,结果表明:基于改进BP神经网络的局放预测模型训练集误差系数为0.0118,测试集误差系数为0.0232.此模型的局放预测值与实际值的曲线趋势基本一致,有效地对变压器局部放电量进行预测,为变压器故障诊断奠定了基础.     

基于DSP及CPLD的掘进机控制系统设计

提出了一种基于DSP及CPLD的掘进机控制系统设计方案,介绍了系统总体设计、CPLD数据采集模块及CPLD逻辑控制模块的设计。该系统采用CPLD实现数据采集,在AD采样环节节省DSP等待时间12μs,25路模拟信号每个采样周期节省300μs;采用CPLD代替标准逻辑器件实现各种逻辑功能,简化了硬件电路的设计,提高了控制系统集成度。实际应用表明,该系统能够满足掘进机正常生产的要求,具有较强的实时性和较高的可靠性。     

基于WSN和数据融合技术的电力变压器故障诊断系统的研究

探讨一种基于数据融合和可拓理论的电力变压器故障诊断方法,基于此方法,应用无线传感器网络技术和.NET开发平台构建和开发出一套电力变压器故障诊断系统。该系统将WSN技术用于电力变压器油中溶解气体的无线数据采集,实现变压器油中溶解气体的实时数据采集和传送;同时运用信息融合技术对数据进行优化处理,既可以降低网络能耗又保证了数据的准确和客观;在变压器进行故障诊断时,针对现有电力变压器故障诊断的气体比值法存在的编码规则不完整、诊断故障类型单一等缺陷,使用可拓诊断方法,定量与定性相结合,使变压器故障诊断方法更为精细化。在线故障诊断可视化系统可以实现变压器油中溶解气体参数的采集、显示、分析、存储和回放等功能,实现对变压器故障信息的实时分析与自动诊断,既解决了作业人员远程实时监测变压器运行状态问题,又大大提高了变压器故障诊断的性能,为变压器在线监测和故障诊断技术提供新的发展方向。     

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.