数字电位器

数字电位器是区别于传统机械电位器的一种由电信号来控制电阻的数字集成电路,一般原理如图1所示,在电阻的高端（RH）和低端（RL）之间集成了若干个电阻,电阻之间抽头,通过控制电路改变Rw接入抽头的位置来改变输出电阻,EEPROM记忆电路（有一些数字电位器并没有记忆电路）保存抽头的位置,下一次上电便能恢复掉电时的电阻值。因此,数字电位器使用效果与机械电位器几乎完全相同,模拟精度取决于电阻阵列中电阻的级数。     

电阻信号,模拟信号的变换电路

A/D转换电路是数字仪表必不可少的组成部分,传感器的电阻信号准确地变换成数字仪表的模拟信号是保证数字仪表精确度的重要第一步。测温的热电阻、应变片的力传感器、可变精密电阻的远传压力表和多圈精密电位器的浮球液位计等都是电阻信号的传感器,其输出的电阻信号和被测参数(温度、压力、液位等)呈现线性关系或非线性关系,需通过不同的变换电路转换为数字仪表的模拟信号。 UQZ型浮球液位计、YTZ型远传压力表和G分度号铜热电阻等,输出的电阻信号和被测参数量程呈线性关系,可采用普通电桥和放大电路,见图1。     

基于LabVIEW的铂电阻器自动测试系统

设计了一种基于LabVIEW的铂电阻器自动测试系统,用于多路铂电阻器的自动、精确测量.采用PXI系列机箱和板卡、四线制测量电阻的方法,进行电阻的测量和通道的切换,应用LabVIEW软件进行数据的采集和信号的滤波.经测试,本系统可有效消除引线电阻和热电动势等误差,测量精度优于0.01％,实现测量的高效率和高精度.     

采用"回避精确增益法"设计高精度程控运放

针对“传统程控运放”和目前“集成数字程控运放”的局限性,提出一种新的程控运放设计方法。该方案采用普通运放、低精度“数字电位器”、模拟开关和电压基准芯片,完成了高精度“程控运放”的设计,从而回避运放的精确增益,不但增益级数可多可少,而且具体增益可通过改变外接电阻任意设定。此设计成本低、精度高、调试简单,尤其适合大批量产品的生产。     

一种数控精密电阻源的设计与实现

设计了一种数控精密电阻源,选择了一种使用继电器切换精密电阻的电路结构,并提出了消除精密电阻初始阻值误差和继电器接触电阻影响的软件校准方法.采用较少的继电器和精密电阻,实现了高精度可变电阻输出.输出电阻值范围为80.00～260.00 Ω,覆盖-50 ～430℃范围内Pt100的阻值变化,具有0.01 Ω步进,误差小于±0.02 Ω,能够广泛地应用于Pt100测温仪表的测试和校准.     

全自动膜片钳USB2.0数据采集系统的硬件设计

针对膜片钳系统全自动化的需要,提出基于USB2.0的高速数据采集系统解决方案。该系统引入了FPGA的控制,使得输入输出同步,采样频率从1kHz到350kHz可调;具有4个模拟输出控制通道和8个模拟输入采集通道;运用数字隔离器件,合理的接地和电位器调节以达到一定的精度。详细介绍了该数据采集系统的硬件设计。     

全自动膜片钳USB2．0数据采集系统的硬件设计

针对膜片钳系统全自动化的需要,提出基于USB2.0的高速数据采集系统解决方案.该系统引入了FPGA的控制,使得输入输出同步,采样频率从1 kHz到350 kHz可调;具有4个模拟输出控制通道和8个模拟输入采集通道;运用数字隔离器件,合理的接地和电位器调节以达到一定的精度.详细介绍了该数据采集系统的硬件设计.     

关于Pt100型铂热电阻温度变送器的研究

提出铂热电阻温度变送器的线性校正和消除引线电阻对测温影响的一种方法，并给出了变送器的电路和设计方法。     

数字电位器在A/D转换中的应用

在许多数字化仪表和单片机控制系统中,均要设计和应用模/数转换器,以便把模拟量转换成数字量,供主处理器处理.数字电位器是一类待殊的模/数转换器,只是它的模拟量输出不是电压或电流,而是电阻.介绍了数字电位器X9312作为模拟量的电阻应用到检测模拟电压中,实现A/D转换的功能.     

嵌入式测试系统用高精度数控恒压恒流源

针对电磁阀产品性能测试的需要,开发了一种基于DSPIC33EV128单片机的数控恒压恒流电源装置.采用UCC27211半桥驱动芯片,由精密采样电阻和AD8417组成精准的输出电流的高边采样,电阻串联分压反馈输出电压,单片机内部数字运用PI闭环算法.电源工作方式可由外部电位器或者采集卡AO模拟量控制,或是PC机串口协议控制,并通过串口上传当前实时电压电流值.实验测试显示,电流、电压调节精度可达1%F.S.     

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。