基于微机并口技术及CPLD技术的新型模数转换接口

以微机并口通讯技术及 CPLD技术为背景 ,论述了一种采用复杂可编程逻辑器件 CPL D并通过微机并行口 EPP工作模式实现的新型高速模数转换接口电路     

基于FPGA的高速信号采集板卡的设计

传统模拟信号采集板卡的低通信速率已成为高性能飞控测试系统功能的"瓶颈",针对这一问题,设计了一种以FPGA为核心的总线型高速数据采集板卡.板卡中信号调理电路有效抑制了模数转换中的零点温度漂移等问题,专用的模数转换芯片提高了采集精度.BLVDS总线与Modbus协议的应用使板卡具有模块化、网络化的功能.设计过程中充分利用...     

一种sigma-delta调制器结构的温度信号转换电路

针对基于CMOS衬底寄生三极管感温的温度传感器的温度信号转换问题,设计了一种sigma-delta调制器结构的模数转换电路。仅使用一个开关电容积分器和一个量化器就实现了温度信号电压到脉冲信号的转换,采用的斩波技术消除了运算放大器输入失调电压的影响,量化器采用预放大器接比较电路再接锁存器的结构,隔离回踢噪声并实现高速比较。电路采用TSMC 0.18μm 1P4M CMOS工艺设计,工作电源为1.8 V,功耗为270μW。仿真表明,系统输出的温度脉冲宽度可正确表示温度的高低。除了温度传感器,设计的Σ-Δ调制器还可用于其他模数转换场合。     

信号串扰对高速模数转换器性能影响的分析

基于实际电路的模数转换系统建立性能分析模型,分析电路信号串扰对转换时钟的干扰,并对转换时钟在信号串扰和噪声影响下的模数转换性能进行研究,推导出有信号串扰时的时钟抖动的模数转换解析表达式,证明转换结果含有和串扰信号频率相关的无穷多项高次谐波分量,并会导致模数转换器性能降低.仿真结果证明了相关分析的正确性,通过试验进一步说明了电路信号串扰对模数转换结果的影响.     

基于FPGA的数字滤波系统设计

为研究基于FPGA的数字滤波系统的设计与实现过程,根据数字滤波系统的基本工作原理在芯片内部设计了模数转换采样控制、基于分布式算法的FIR滤波器以及基于FFT IP核应用的频谱分析电路等功能模块,并给出了QUARTUS Ⅱ平台上的系统设计时序仿真波形.实验结果表明,相比于一般实现方法,基于FPGA实现的数字滤波系统具有高速灵活的优点,FPCA可广泛应用于高速数字信号处理领域.     

简析AD6644及其应用

数模转换在当今信息通讯及信息处理领域中起着重要的作用,作为数模转换的芯片及设备系统的设计与开发建立也显得尤为重要。作为高速14位数模转换的AD6644,它包含采样保持电路和基准源,同时保持了精确变换宽带模拟信号,而且AD6644也具有低噪声、低失真的特性,它在实现软件无线电和多通道模数转换系统中表现了良好的设计特性。本文从模数转换的理论概念出发,分析了AD6644的特性和结构,并通过其具体领域的应用来进一步阐述其相关特性,旨在为工程实践起到一定指导意义。     

适于微波成像的高速高精度数据采集系统

文中给出了一种基于ＩＢＭ－ＰＣ的用于微波生物体医学成像的复数数据采集系统。它以两片１６位的模数转换芯片ＡＤ７８８４ＡＱ为核心，构成一个正交双通道的高速高精度的数据采集系统。还给出了系统的硬软件结构和主要硬件单元电路，并简要说明了系统的抗干扰措施。     

用ATmega128控制的多道脉冲幅度分析系统

采用AVR单片机ATmega128作为主控制器,取代C51系列单片机,设计了一套性能优良带有USB接口的多道脉冲幅度分析系统。本文给出了ATmega128控制峰值保持、高速模数转换及USB接口的电路原理简图。目前其已应用到我校4兆伏静电加速器的核辐射监测系统中。     

一种改进的流水线ADC开关电容电路

为降低流水线模数转换器(ADC)中跨导运算放大器(OTA)设计要求,在分析已有开关电容电路(SC)误差消除技术和流水线ADC误差源的基础上,提出一种改进的流水线ADC开关电容电路及与其匹配的OTA设计方案.采用交又差分结构,对虚地电容进行了修正,并将电容失配参数在系统传输函数中消去,使开关电容电路对OTA的增益误差要求降低,并使其瞬态功耗下降.采用CMOS 0.18üm工艺设计了一个分辨率为8位、取样速率200 MHz的ADC作为验证原型,仿真结果表明,该优化结构符合ADC电路高速低功耗要求,可作为信号前端处理模块应用到模数转换电路中.     

基于USB总线的微型虚拟示波器的研制

该文从硬件系统和软件系统两方面对基于USB总线的微型虚拟示波器系统设计作了详细论述,着重探讨了系统设计思想及相关注意事项。给出了示波器前置程控放大电路、高速模数转换电路和USB通信模块的设计方案和原理框图。对驱动程序和虚拟仪器软件开发思想进行了阐述。最后,给出了系统在高等教育实验教学中的应用实例和测试结果。实践表明,微型虚拟示波器实现了微型化、智能化和网络化,代表了测试测量仪器的发展方向。     

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。     

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。