舰船电网谐波干扰电磁滤波器的设计仿真

船舶电网的电磁滤波器的性能优化可提高舰船电网设备抗干扰性能.由于舰船在恶劣的环境下工作,舰船电网的干扰过程较为复杂,干扰中的低频噪声混淆特征明显,谐波干扰频率呈现多样性、叠加性、非线性的特征极其明显.传统的电磁波滤波器设计以信噪比异常特征过滤为基础,存在低频段区域敏感性过高的问题,无法对低频部分的谐波干扰进行信号提纯,现有滤波器无法做到自适应频率阀值调节,过滤效果不好.提出一种自适应舰船电网谐波干扰电磁滤波器设计方法,给出了滤波器的总体结构,设计的硬件模块由电感器、电容器、开关电源模块以及传导发射模块等模块组成,给出了差模干扰和共模干扰下,两种插入损耗的等效电路,软件是由自适应软件过滤算法构成,经过自适应滤波处理的过程,完成电磁滤波器元件的校核处理过程,实现舰船电网谐波干扰下电磁滤波器自适应噪声抑制.实验结果说明,所设计的电磁滤波器达到预期的控制效果,可对复杂舰船电网谐波干扰进行有效的滤波处理.     

小波变换在并联型有源电力滤波器中的应用

研究改善电网系统谐波的问题,电力系统中存在许多非线性负载,由此产生的谐波对电网的电能质量造成很大的影响,影响线路传输能力,并联型有源电力滤波器(SAPF)是抑制电网谐波电流的有效手段,主要包括谐波检测和跟踪控制两部分,其中谐波检测是有源电力滤波器的关键技术,分析了小波变换理论,并将其应用于电网谐波检测中,用仿真软件MAT-LAB对基于小波变换的谐波检测方法进行了仿真分析与研究,同时搭建了基于小波变换的并联型有源电力滤波器系统的仿真模型,仿真结果表明小波变换的并联型有源电力滤波器能够有效地抑制电网谐波电流,提高了电网传输效率。     

超声波硫酸分析回波波至点确定方法研究

在超声硫酸浓度分析过程中,系统内部和外界环境存在很多干扰噪声,因此无法准确确定超声波回波波至点的位置,故采用小波分解方法加以解决.针对超声波信号的非奇异性,首先对信号进行HiIbert变换;然后再进行拟小波分解和阈值滤波;最后,利用FPGA构建小波变换模型并找到波至点.研究结果证明,该方法可以准确确定波至点,大大提高了硫酸浓度测量的精确度.     

基于小波变换的电网谐波电流检测研究

电网谐波电流检测是电力系统质量分析和谐波补偿的关键技术,对小波变换在电网中的谐波电流检测原理进行了研究.根据小波变换的多分辨率分析,采用Mallat算法对电网谐波电流检测进行实现,将电网电流中的基波电流和谐波电流分离,并对小波变换谐波检测小波基的选取原则进行了分析,在基于TMs320F2812DSP的实验装置上进行了小波变换谐波检测实验.实验结果表明,该方法具有较高的检测精度.     

面向多逆变器的电网电压前馈控制仿真

为了有效避免额外引入电流影响电力系统的稳定性，提出面向多逆变器的电网电压前馈控制方法。分析LCL滤波器的滤波特性，获取LCL滤波参数计算结果，同时对多逆变器建模处理。分析满足逆变器稳定运行的基本条件，调节公共耦合点处的电网阻抗和逆变器输出阻抗，引入理想前馈函数抑制电压对并网电流的干扰，获取逆变器输出阻抗的频率特性，将其和电网电阻相匹配，实现电网电压前馈控制。仿真结果表明，所提方法能够有效抑制谐波的产生，获取比较满意的前馈控制效果。     

多聚焦图像融合方法仿真研究

研究了多聚焦图像融合问题.针对焦点不同的图像融合后,在传输过程中由于受到不同的噪声的干扰造成结果清晰度不高等问题,为了提高图像的清晰度,提出了一种改进的多小波变换多聚焦图像融合算法.首先利用不同的小波对待融合图像进行小波分解,采用多尺度双结构元对输入图像进行滤波,在融合规则选择中,采用加权平均法选择高频系数,采用绝对值...     

基于小波变换Mallat算法的电网谐波检测方法

针对传统的傅里叶变换方法在分析非平稳运行电网的电量信号时误差较大的问题,提出了一种基于小波变换Mallat算法的电网谐波检测方法。该方法根据不同的分辨率将电量信号分解到不同的子频段,然后分别对子频段进行多次重构,得到原始信号的基波,最后将采样得到的原始信号与重构的基波信号相减,得到谐波信号。Matlab仿真结果表明,该方法能够有效地将电量信号中的基波与谐波成分分离,谐波检测精确度较高。     

基于小波神经网络的大功率电器识别技术研究

针对公寓用电中的大功率电器识别问题,提出利用小波神经网络对大功率电器进行识别.由于采集到的电网电流信号是基波信号和谐波信号的混合,因此需要进行信号分离.基于Mallat快速算法进行小波变换提取其中的谐波电流信号;将总电流的平均功率增量和谐波电流的平均功率增量经过归一化处理后作为大功率电器识别的特征向量,利用得到的特征向量对融合型小波神经网络进行基于BP算法的网络训练;利用训练好的小波神经网络对未知的电网电流数据进行识别,实现大功率电器的在线识别和预警.对比仿真实验表明:利用小波神经网络对大功率电器识别比传统的BP神经网络有更高的准确率.     

基于中值和小波变换的α稳定分布噪声滤波方法*

针对信号中厚尾噪声的抑制问题,提出基于中值和小波变换的滤波方法。研究了α稳定分布信号的特性,利用中值滤波有效地抑制噪声中幅度异常的强脉冲信号,然后对结果利用小波阈值方法进行消噪。实验对α稳定分布噪声进行模型描述,分别采用高斯模型分析方法和中值滤波结合工程算法对采样信号进行时频变换。系列图谱对比结果表明,在不同冲击性α稳定分布噪声环境下,采用高斯模型分析结果出现退化,而采用中值滤波结合小波变换的滤波方法能有效抑制异常值,减小了信号的畸变,能够实现降噪。     

无功与谐波补偿检测的光伏并网仿真研究

研究了光伏电源并入配电网后对电能质量的影响.从理论上分析了对光伏并网发电系统进行无功补偿和消除配电网谐波的方法,利用瞬时无功功率理论检测系统无功及谐波电流,将无功和谐波补偿策略与光伏发电控制相结合.仿真结果表明,光伏电源并网能够较好地补偿系统无功和负载谐波,对提高负荷特性和电网的电能质量、减小电网电流谐波有显著的效果.     

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。     

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.     

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.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.