一种基于温控半导体激光波长扫描的光纤瓦斯测量系统

设计了一种基于温控半导体激光波长扫描的光纤煤矿瓦斯测量系统,通过改变中心波长1653 nm半导体分布式反馈( DFB)激光器的工作温度来扫描半导体DFB激光器的输出波长,在5 nm波长扫描范围内,存在明显的瓦斯气体吸收峰。半导体DFB激光器输出的光注入被测气体室,气体室的输出光携带有瓦斯气体浓度信息,用光电探测器将光信号转化为电信号,再由A/D采集卡采集到信号处理系统,通过对有吸收峰位置的光功率和无吸收峰位置的光功率进行比较,则可计算出瓦斯浓度。该传感系统采用80 mA恒流源驱动半导体DFB激光器,使其输出光强保持不变,其结构简单、灵敏度高。     

差动式半导体激光位移传感器模型

本文提出了一种利用半导体激光自混合干涉效应的差动式位移传感器测量系统,建立了系统的数学模型,给出了用小范围内位移测量精确的表达式,与其他几种自混合型半导体位移测量方法相比,本文的结果不仅精确度高,且分辨率也在提高。     

光反馈自混合干涉信号的小波去噪处理

介绍了光反馈自混合干涉系统模型.阐述了基于小波变换的去噪原理.分析了小波多分辨率分解与重构法和非线性阈值去噪法.利用两者相结合的方法有效地消除了光反馈自混合干涉信号中的高频噪声.     

分布式多点激光甲烷检测系统研究

针对传统甲烷检测系统存在的易受环境影响、检测精度低、稳定性差等问题,基于可调谐半导体激光吸收光谱技术和空分复用技术,设计了一种分布式多点激光甲烷检测系统。该系统采用波长1 653.7nm的分布式反馈半导体激光器作为光源;利用谐波检测法得到二次谐波和一次谐波信号幅值比来反演甲烷浓度;采用1分8光分束器,并结合参考气室实现多个测点甲烷浓度的实时检测。在实验室环境下对该系统进行了测试,结果表明该系统测量准确性高、稳定性好,可实现10km范围内测点的有效覆盖,在2.00%~85.0%甲烷浓度范围内,系统测量误差小于2%。     

光纤法珀振动传感器时分三波长解调技术

针对非本征型光纤法布里-珀罗干涉(简称EFPI)传感器的动态解调，提出一种基于可调谐激光器的时分三波长解调方案。基于可调谐激光器波长切换速度快、调谐范围宽的优点，采用波长切换的方式来代替传统的3台激光器，简化了解调系统。实验结果表明，解调方案的最大非线性误差为2.3%,解调速度为78 kHz。该解调技术具有系统简单紧凑、成本低、速度快等优点，在动态信号测量领域具有一定应用价值。     

基于电子散斑干涉术的残余应力测量

提出一种电子散斑干涉术与钻孔法相结合的残余应力的测量方法,设计了一种测量残余应力的装置。该装置采用半导体激光器实现了紧凑的双光束干涉光路,从而使该装置体积小便于安装和测量。装置中的整个光路和CCD布置在倾斜平面上,避开钻孔方向,实现了残余应力的实时测量。通过试验对单向压缩残余应力进行了测量,对比了试验结果与实际值,证明了该方法的可行性。     

光反馈激光器非线性仿真研究

一些传统计算方法对非线性系统的分析存在着一些困难。针对光反馈半导体激光器收发系统微分方程组的特点,对非线性性质做出了数学上的分析,考虑到在光反馈半导体激光器收发系统中,其微分方程含有延迟因子,无法直接利用多节点上的值的加权和来近似计算斜率。基于龙格-库塔法提出了一种有效的数值仿真算法,并在matlab平台上对给定参数条件下的发射端与接收端的归一化光场以及同步误差进行了仿真,证明了接收端光场信号可以很快与发射端光场信号一致,仿真结果表明仿真算法能有效对系统进行仿真分析。     

LD温度控制系统在光纤磁场传感器中的应用

光纤磁场传感器所使用的磁光晶体的法拉第旋转角会随着入射光波长的不同而不同,半导体激光器的工作温度对输出波长有很大影响。因此,必须对半导体激光器的工作温度进行高准确度的控制才能使光纤磁场传感器工作稳定。利用单片机驱动半导体致冷器对半导体激光器进行温度控制,不仅简单,而且温度控制稳定、准确度高。可使半导体激光器的输出波长保持稳定,保证了光纤磁场传感器的测量准确度。     

基于可调谐激光器的光纤法珀振动传感器解调技术

针对非本征型光纤法珀干涉仪动态解调,研究了一种基于可调谐激光器的双波长正交相位解调方案。可调谐激光器具有波长切换速度快、调谐范围广的特点,克服了传统双波长正交相位解调中光功率不平衡和直流分量难以计算的问题。利用可调谐激光器宽范围的线性扫描(1530-1560 nm)得到EFPI传感器的干涉谱,通过干涉谱计算出EFPI传感器的初始腔长122.581μm和直流分量3.4 V,同时确定两正交波长,然后利用反正切原理对EFPI传感器的腔长进行解调。搭建双波长正交相位解调系统,在2.25 kHz的频率以及不同的加速度下,对EFPI振动传感器进行解调。结果表明,该系统可实现不同腔长变化量的解调。     

激光器电压调制驱动与锁相放大电路的研究

为解决光频漂移对气体浓度检测的影响,根据分布反馈式半导体激光器的波长可调制特性,设计了一种激光器电压调制驱动与锁相放大电路。该电路的电压调制驱动电路输出波形是2 Hz的锯齿波和2 kHz的方波的叠加,其中:2 Hz的锯齿波使激光器的中心波长缓慢扫过气体吸收中心线,确保气体吸收光强;2 kHz的方波一方面对激光器的波长进行二次微量调节,另一方面作为谐波检测的同步信号。锁相放大电路则对不受激光器波长漂移的激光调制信号3次谐波进行锁相放大。Matlab仿真结果表明,该电路的输出与模拟气体浓度吸收光强函数的幅值成比例,同时证实了检测3次谐波的可行性。     

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。