浅谈光缆有线电视——光发射器件与交接收器件

目前光纤通信全部采用半导体激光器(Laser diode简称 LD)做发射光源,光探测器也全部采用半导体光电探测器(Photo diode简称PD),但在光缆CATV系统中,仍有一部分采用YAG固体激光器做光源.但从光缆CATV的普遍性和发展来看,半导体激光器占绝对优势,所以这里着重讨论半导体激光器和半导体光电探测器.     

功率稳定可调LD驱动电路的设计

功率稳定可调的激光二极管(LD)在精密光电检测和光纤通信系统中应用广泛。介绍了:一种单片机控制激光二极管输出功率的方法,针对SANYO30mW红光LD设计了驱动电路,其驱动电流在0～100mA之间可调,最小可调量<0.01mA。单片机片内对监测电流偏差进行了PID调节运算,使激光二极管输出功率稳定。     

背投电视会聚自动校正系统的芯片化方案

根据背投电视会聚原理的特点,提出一种简单的智能背投电视会聚偏移校正解决方案。使用Freescale公司8位微控制器MC68HC908LD64和会聚芯片CH3102AZC及光电传感器,设计实现会聚的三基色偏移校正。该设计已经在批量生产的背投电视上应用。     

学习设计再生器的研究

为了提高LD(Learning Design)文件的制作效率和保证其顺利执行,在分析LD文件及其制作规律的基础上,开发了一个由LD搜索器和LD装配器两部份构成的LD再生器,其工作原理:首先,由LD搜索器搜索符合设计者要求的已有LD文件和部件,为设计者推荐最佳的可利用方案;其次,由LD装配器引导设计者对LD部件进行修改、验证;最后,LD再生器自动生成新的LD文件.实践表明:利用LD再生器制作LD文件,不仅降低了设计LD文件的复杂性,还减少了大量的重复性工作.     

基于光谱吸收的光纤水分传感器研究

基于分子的近红外光谱吸收机理,研究一种可以检测水分含量的光纤传感器。对半导体激光器(LD)进行正弦波调制,建立人工神经网络的数学模型,利用NI数据采集卡和神经网络数据拟合实现分子的检测。系统采用双光路结构有效消除了光源光强噪声干扰和光电器件的零点漂移。实验结果表明:传感器性能稳定,灵敏度高,重复性好,并且不受其它气体或杂质的干扰。     

基于正弦调制的激光平面测量系统的研究

针对高精度的大平面测量,构建了一种基于正弦调制的激光平面测量系统。该系统以激光器（LD）为光源,位置敏感探测器（PSD）为光电探测器,通过柱面透镜扩束获得测量基准平面一激光平面。分析了影响系统测量精度的主要因素,提出采用光源正弦调制的方法,以提高测量系统的抗干扰能力。实验结果表明：该系统具有较高的测量精度和输出稳定性。     

连续LD特性参数测试中的驱动控制系统

针对连续半导体激光器(LD)特性参数测试的需要,研制了一种新型的连续LD驱动控制系统.利用改进的自动电流、自动功率和自动温度控制原理,结合极性控制电路、LD和制冷器TEC保护电路,设计了LD驱动控制模块.采用单片机控制技术,实现对整个系统的功能控制和参数显示.实验测试表明,该驱动控制系统的电流稳定度高达0.01%,温度控制精度优于±0.01 ℃.     

梯形图数据依赖关系分析与并行提取

程序依赖关系分析在对程序进行测试、维护、分析和优化过程中起着重要作用。梯形图(LD)程序中数据定义和数据引用会导致梯级之间存在数据依赖关系和潜在并行性。针对该问题,通过构造数据依赖关系有向图构建数据依赖关系,提取LD图梯级间的数据流和数据依赖信息,并从数据依赖关系有向图中获得LD图并行梯级。实验结果表明,通过并行提取可使LD图的扫描周期缩短至原来的20%~50%。     

光纤传感器光源驱动技术研究

驱动电流和有源区温度是影响激光二极管LD、超辐射二极管SLD的光强及光谱稳定性的关键因素。通过控制这些因素,LD/SLD的输出光强稳定性达到了0.5%和0.1%,并可使光源在-30～50℃环境温度范围内正常工作。     

LD调制技术在光学式甲烷气体传感器中的应用

设计了一种基于光谱吸收式光学式甲烷气体传感器的调制电路,利用波长调制光谱技术(WMS)实现对LD激光器的调制,降低LD中心波长的波动对测量结果的影响.介绍了LD调制的基本原理,给出相应的硬件电路,并重点分析了在光学式甲烷气体传感器中应用LD调制的原理及关键技术.结果表明:该传感器响应时间为12s,测量精度可达0.03%...     

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.