一种新型DSTATCOM用于电弧炉柔性供电的研究

本文研究一种新型DSTATCOM应用于三相交流电弧炉的柔性供电方法。运用dq矢量变换法,检测冲击性电弧炉负荷的瞬时无功电流;采用电流直接控制法,使DSTATCOM产生无功补偿电流,以此抑制电网电压波动与闪变。应用PI控制使逆变器直流侧电容电压保持稳定,保证DSTATCOM良好的电流跟踪性能。以某钢厂炼钢电弧炉供电系统为背景,在MAT-LAB下对此柔性供电系统进行了仿真。结果表明此新型柔性供电方法能有效地抑制电弧炉引起的电网电压波动与闪变,实现柔性供电的目的。     

一种新型DSTATCOM用于电弧炉柔性供电的研究

本文研究一种新型DSTATCOM应用于三相交流电弧炉的柔性供电方法.运用dq矢量变换法,检测冲击性电弧炉负荷的瞬时无功电流;采用电流直接控制法,使DSTATCOM产生无功补偿电流,以此抑制电网电压波动与闪变.应用PI控制使逆变器直流侧电容电压保持稳定,保证DSTATCOM良好的电流跟踪性能.以某钢厂炼钢电弧炉供电系统为背景,在MATLAB下对此柔性供电系统进行了仿真.结果表明此新型柔性供电方法能有效地抑制电弧炉引起的电网电压波动与闪变,实现柔性供电的目的.     

对抚钢引进50吨超高功率电弧炉引起的电网电压波动及闪变的研究

本文是对抚顺钢厂引进的50吨超高功率电弧炉运行对电网产生的电压波动及闪变问题研究总结的一部分。文中介绍了初选变压器容量，预测其运行时产生的电压波动及闪变电压值，分析其对电网影响程度，并与投产后实测值比较，其结果验证了预测计算方法的准确性。文中重点论述了计算公式中最小系统短路容量选择技巧，以得出切合实际的预测结论。可供新建电炉设计及运行者参考。     

开关电源中液态铝电解电容器失效分析

本文阐明了铝电解电容器的主要失效为磨损失效,通过数据、图表分析了纹波电流、电压、温度、频率对电容器失效的影响。     

电能质量检测的研究与仿真

根据相关国家标准中的电能质量的5个指标,从测量精度和软硬件实现难度两方面因素考虑,确定各指标的测量方法.采用快速傅里叶变换(FFT)分析电网谐波,通过跟踪电网频率,实现准同步采样,解决FFT的频谱泄露问题.利用FFT的运算结果,在频域里计算出电压电流的有效值,电压偏差、功率和功率因数、三相不平衡度.闪变的测量采用IEC的测量原理,并对其作了修正,通过双线性变换,实现了闪变测量的数字化.     

电网电压不对称跌落下直驱风电系统控制策略

针对电网电压不对称跌落下直驱风电系统并网运行过程中出现的直流环节过电压、并网电流畸变、并网功率波动问题,在直驱风电系统并网变换器的直流环节并联超导磁储能系统;同时在分析电网电压不对称跌落下网侧变换器数学模型的基础上,采用抑制并网功率波动的正负序电流控制对网侧变换器的控制策略加以改进,从而稳定直流环节电压、改善并网电流品质、抑制并网功率波动。仿真结果验证了该控制策略的正确性和有效性。     

电网电压不平衡工况下双馈感应风力发电机组的自抗扰控制

本文提出电网电压不平衡工况下双馈感应电机(DFIG)的自抗扰控制(ADRC)方法, 抑制不平衡电压引起的电磁转矩和无功功率波动, 延长风力发电机组的工作寿命. 在正、负序同步旋转坐标系中推导了电网电压不平衡工况下DFIG的电磁转矩表达式, 计算出消除电磁转矩波动所需的负序转子电流, 将其叠加到正序转子电流参考值上, 以减小电磁转矩波动. 采用ADRC实现对转子电流的有效控制, 减少控制器对发电机精确模型的依赖, 提高控制系统的鲁棒性. 仿真结果表明所提出的控制方案有效地减小了电网电压不平衡工况下DFIG的电磁转矩和无功功率波动, 同时减小了不平衡电流, 有利于延长DFIG风力发电机组的工作寿命.     

电网电压不对称跌落下直驱风电系统控制策略

针对电网电压不对称跌落下直驱风电系统并网运行过程中出现的直流环节过电压、并网电流畸变、并网功率波动问题,在直驱风电系统并网变换器的直流环节并联超导磁储能系统;同时在分析电网电压不对称跌落下网侧变换器数学模型的基础上,采用抑制并网功率波动的正负序电流控制对网侧变换器的控制策略加以改进,从而稳定直流环节电压、改善并网电流品质、抑制并网功率波动。仿真结果验证了该控制策略的正确性和有效性。     

基于直接电流控制的D-STATCOM数学建模与控制系统仿真

配电网静止同步无功补偿器D-STATCOM是用户电力的重要设备,能够有效解决配电网中电压波动与闪变、三相电压不平衡、电网谐波污染等电能质量问题,是目前国内外研究的热点。本文建立了D-STATCOM的动态数学模型,依据瞬时无功理论以及直接电流控制方法对D-STATCOM的控制系统进行了设计,并根据所述数学模型和控制系统搭建了D-STATCOM的仿真模型,进行了仿真分析。仿真结果表明,本文所述的基于直接电流控制的D-STATCOM具有很好的补偿效果,对于容行和感性负载均能准确检测并迅速补偿,动态性能良好。     

经验模态分解及Hilbert谱分析在电压闪变检测中的应用

文章应用基于经验模态分解（EMD）和Hilbert谱分析的Hilbert-Huang变换,进行电压波动与闪变信号的分析与检测,并对应用中的一些问题进行了探讨;应用研究表明,对暂态闪变信号进行EMD分解,再对得到的各IMF分量求HHT谱,可以精确地检测到暂态电压波动发生的时刻和终止的时刻;采用Hilbert-Huang变换进行电压闪变调幅波信号的包络解调,可以避免电网工频高次谐波对解调的影响,从而提高闪变分析的精度;所作的一些尝试表明,应用Hilbert-Huang变换分析电压闪变信号是可行的和有效的.     

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     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

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。