基于89C51 & SA4828的SPWM三相逆变电源设计

提出了用高精度三相可编程PWM集成芯片SA4828与89C51单片机控制技术相结合的三相逆变电源的设计方案,阐述了SA4828的基本原理、特性及其应用SA4828设计静态逆变器的方法,介绍了三相大功率逆变器的控制单元电路、各种检测保护电路和软件控制的设计原理与设计过程,实验验证了从静止逆变器中产生了预期的PWM波形,实现了高质量的正弦波.     

智能复用型电磁搅拌电源控制系统研究

介绍了智能复用型电磁搅拌电源控制系统设计。通过三相电压之间的矢量关系的分解,得到对于普通的三相逆变电源固定其中两相幅值,仅需改动另一相的幅值即可实现二相正交电源的输出。为此,文章设计了由MCU与专用PWM波发生芯片SA4828构成的电磁搅拌变频电源控制系统,且着重分析了SA4828的程序设计要点。该方案具有电路简单、控制方便和运行可靠等优点。     

基于SA4828的三相逆变电源中消谐的实现

阐述了三相高精度PWM产生器SA4828芯片的工作原理、控制方法并对其运行参数进行设计。通过对芯片进行参数设定来启动PWM波形输出,根据逆变后进行采集而得到的谐波情况,进行谐波补偿,对芯片控制参数进行改动设置从而改变输出波形,通过闭环控制最终实现三相逆变电源输出纯正弦波。     

智能型PWM运动控制器SA4828及其应用

本文介绍了一种智能型、高精度PWM运动控制器SA4828,其控制实行全数字化,硬件电路简洁、可靠。文中最后给出了变频器控制的实例。     

程控SPWM电路的设计方法

介绍了一种基于单片机控制的三相SPWM发生器，采用了SA4828芯片，具有电路结构简单，全数字控制，不占用微机资源等优点，给出了接口的硬件电路和程控参数。     

单片机与SA4828控制的SPWM变频电源

本文利用微处理器作为控制器,结合专用的SPWM集成电路,设计三相SPWM变频电源.系统主电路形式采用AC-DC-AC结构,逆变部分选用IGBT单元模块加上并联缓冲电路.输入采用三相全渡不可控整流电路,提高了系统的功率因数.系统控制电路由MCS-51系列的8051单片机最小系统和SA4828三相SPWM产生器及少量的扩展外围芯片构成,系统实现了变频电源的全数字化控制.     

SA4828组成的变频器的软件设计

利用大规模专用集成电路SA4828设计变频器,可以大大降低CPU的资源占用,简化硬件电路和软件编程。通过对SA4828进行初始化编程,可以方便地设定变频器的基本参数包括:载波频率、调制波频率范围、死区时间、最小删除脉宽、看门狗时间常数、输出波形、频率、幅值、正反转控制等。实验表明,由SA4828组成的变频器,电路简单,操作方便,运行稳定可靠。     

架线式窄轨矿用电机车辅助电源的设计

窄轨机车上的辅助设备需要三相交流电,以AT89C51单片机为核心,利用专用芯片SA4828来产生SPWM来控制主电路IGBT的通断,实现了接触网的直流电逆变成辅助设备需要三相交流电。控制电路简单、结构紧凑、降低了成本且提高了可靠性。     

AT89S52的交流异步电机变频调速系统

交流异步电动机因为结构简单、价格便宜、维护方便的特点,在生产和生活中得到了广泛的应用.本文以AT89S52为控制核心,以SA4828为速度控制芯片,以智能功率PS21564智能功率模块为集成驱动电路,对一台三相异步电动机进行控制.     

磁滞电机高精度电源的一种设计和实现方案

本文介绍了三相PWM产生器SA8282的基本工作原理，及其在磁滞电机测试专用电源中的应用，并给出了电路硬件、软件设计方案。     

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。     

基于QTE的蒙古文显示机制研究与实现

蒙古语言是中国蒙古族使用的通用语言,由于蒙古文区别于其他文字的书写方式和其自身变形机制等特点,在很多通用的文字处理引擎中都不被支持。在嵌入式产品开发与应用领域中Linux加QTE已经成为流行方式。该文给出了一种在QTE环境上实现基于标准Unicode的蒙古文点阵显示和变形算法, 并自定义了支持蒙古文的QTE组件,扩展了QTE功能,为在Linux加QTE方式的嵌入式体系结构中处理蒙古文提供了一种解决方法。