基于SG的Boost变换器T-S模糊建模与控制

针对Boost变换器的非线性特性,基于分段线性电子电路仿真(PLECS)软件建立了电感电流连续状态下Boost变换器的仿真模型,采用T-S模糊控制方法设计了控制器,提出了一种用SG对Boost变换器控制器实现的新方法,并分析了负载及电源电压变动下的控制性能.仿真结果表明PLECS建模的正确性和T-S模糊控制器优越性,且验证System Generator设计开发的有效性.     

基于传输线模型的开关变换器数字仿真

瞬变过程和动态特性分析在开关变换器的研究设计中占有重要地位.阐述了一种以传输线理论为基础的开关变换器离散数字建模方法-传输线建模方法及其无条件数值稳定性,以Boost变换器为例建立了仿真模型,并对仿真和实验结果进行了比对.仿真结果精确地描述了实际电路的动态过程,在步长从0.02μs到0.2μs范围内变化时,结果保持稳定.这种方法简单实用,物理概念清晰,能有效地对开关变换器进行仿真研究.     

基于注吸电流法的Buck-Boost变换器建模与仿真

该文详细介绍了注吸电流法的建模思想和步骤，并应用注吸电流法建立了工作在电感电流断续（DCM）模式下的Buck—Boost变换器数学模型。对Buck—Boost变换器及其PI调节器构成的闭环控制系统进行了分析研究。应用Simulink＼Sim-owerSystem模块，建立了该系统的Matlab仿真模型，并进行了相应的仿真分析。仿真结果表明，所得Buck—Boost变换器数学模型的精确性和可用性可以满足要求，能够真实反映该系统的动、静态性能。满意的仿真结果与理论分析取得了一致，验证了该模型的正确性。     

基于Multisim的Boost变换器仿真

为简化Boost变换器的电路设计,应用Multisim 10对Boost变换器进行建模,并对全部工作过程进行仿真和分析. 根据电流采样电阻、电感和负载的不同,给出仿真波形和数据. 电路测试显示,电路性能能够很好地满足输出电压的设计要求,表明仿真结果正确.     

电压前馈控制升压变换器输入输出阻抗分析

在电力系统变换器优化设计的研究中,针对直流分布式系统中变换器稳定性问题,提出了一种基于输入输出阻抗分析稳定性的方法.以常见的基本Boost DC/DC变换器为例,采用电压前馈控制,对变换器的输入输出阻抗进行建模.在连续导电模式(continuous conduction mode,CCM)下分析了小信号模型Boost DC/DC变换器输入输出阻抗的特性,研究影响阻抗变化的因素.在上述基础上,根据阻抗比稳定性判据,为直流分布式系统变换器级联设计及稳定性分析提供参考依据.     

基于时间尺度的Boost变换器自抗扰控制

以Boost变换器的控制策略为研究对象,将自抗扰控制技术应用到Boost变换器的控制策略中,使被控系统不但具有良好的动态特性,而且对参数变化具有较强的鲁棒性.同时针对自抗扰控制参数难以整定的特点,介绍了自抗扰控制的参数整定基本原则,对Boost变换器进行自抗扰控制仿真,并和PID控制进行对比.最后,用时间尺度概念对Boost变换器的自抗扰控制进行参数整定.仿真结果验证了该方法确实可行.     

Boost变换器和Boost-ZVT变换器的比较研究

介绍普通Boost 变换器和Boost-ZVT变换器的工作原理,指出Boost 变换器的开关管工作在硬开关状态,而Boost-ZVT变换器的主开关管工作在软开关状态。通过理论分析可以知道Boost-ZVT变换器的效率更高,然后将两种电路应用于单相功率因数校正电路中。最后在Pspice软件环境下搭建功率因数校正电路Boost变换器与Boost-ZVT变换器的仿真模型并进行仿真,并对仿真结果进行分析和比较,指出了它们各自的优点与缺点。     

DC-DC功率变换器中非线性现象的仿真研究

DC-DC开关变换器中蕴涵着丰富的非线性现象,混沌与分岔在变换器中存在着一定的产生机理和表现形式.对两种基本拓扑结构DC-DC变换器Boost、Buck的非线性现象进行了仿真研究,建立了两种变换器的离散迭代映射模型和精确开关模型,经过数字仿真,验证了存在于DC-DC变换器中的分岔和混沌现象.对闭环控制Boost变换器,深入分析了采用离散迭代模型和精确开关模型后仿真结果的差异及原因.所采用的数值仿真方法为DC-DC变换器的电路参数优化提供了理论工具.     

并联Boost变换器T-S建模与控制

在并联Boost变换器建模过程中,含有状态量的输入矩阵使得模型具有非线性特点,本文针对并联Boost变换器的这一特点,建立Boost变换器等价T-S模型,并根据建立的模型,利用Lyapunov函数方法和线性不等式方法,采用并行分配补偿(PDC)策略设计非线性T-S模糊控制器。仿真结果表明:本文所建立的并联Boost变换器的模型是准确的,设计的T-S模糊控制器是可靠的,系统工作稳定并且具有较强的抗扰动性能。     

基于Agent的复杂系统分布仿真建模方法的研究

基于Agent的分布仿真是研究大型复杂系统的一种有效的、重要的方法。为了减小复杂系统仿真的复杂度,增加仿真模型的重用和可维护性,需要研究基于Agent分布仿真的建模方法。首先对复杂系统及其特性进行了分析,对基于Agent的仿真进行了全面的论述,然后对基于Agent的复杂系统仿真中的复杂系统建模分析、Agent建模分析以及Agent的分布进行了分析,给出了基于Agent的复杂系统分布仿真的建模步骤,最后给出了在此建模思想指导下的金融证券市场的建模过程。     

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.