时分复用光纤光栅传感阵列中DFB激光器的高精度温控设计

针对时分复用光纤光栅(TDM-FBG)传感阵列中使用的分布反馈(DFB)激光器高波长稳定度的要求,设计了一个高精度的DFB温控方案,包括温度测量与设定、热敏电阻线性化、PID补偿回路、H桥驱动、温度电压采集与显示等。使用DFB内置的热敏电阻和半导体制冷器(TEC)对温控电路进行了测试,其精度在180s内达到±0.04℃,温控后激光器温度变化引起的应变测量误差为±3.4με左右,满足TDM-FBG传感阵列的要求。     

高功率脉冲半导体泵浦激光器阵列电源的设计

为满足高功率脉冲半导体泵浦激光器相干合成的特殊需要,设计6路同步输出的电源阵列,实现了工作电压0~400 V自适应调整、工作电流0~1 200 A、脉冲宽度200μs~1 000μs、重复频率1 Hz~20 Hz均可任意调整的高电压、大电流脉冲输出。在保证技术指标实现的同时,着重解决阵列电源的同步输出、电压自适应和可靠性保护等问题。试验结果表明,该阵列电源的同步一致性可达到99%,输出电流精度达到0.1 A,已在"六路激光相干合成"研究中得到应用。     

半导体激光器双闭环温度控制系统

为了提高半导体激光器输出波长的稳定性,研制了一套双闭环温度控制系统。其中,外环温控以集成化模块MTD1020T为核心,通过优化数字式PID参数,最大可驱动20 W的热电制冷器(TEC),可实现±0.5℃的温控精度;内环温控以控制芯片LTC1923为核心,通过增加差分放大环节及设置PI环节,可实现±0.01℃的温控精度。实验结果表明,双闭环温控系统可将外环快速、大功率温控与内环高精度温控相结合,能够在20 s内实现±10℃的温度调节,4 h内其温控准确度控制在±0.02℃内。该温控系统具有可控范围宽、响应迅速、集成度高等优点,可应用于飞行器气体浓度探测等便携式气体探测领域。     

基于PID算法的大功率泵浦激光器温控系统设计

设计了一种基于数字PID算法的大功率泵浦激光器温度控制系统,该系统采用ARM2210作为处理器,高精度NTC（负温度系数热敏电阻）和TEC（半导体制冷器）分别作为温度传感器和温控执行元件,并对传统的PID算法和参数进行改进和整定、修正,驱动芯片选用MAX1968,在节省大量电路设计的同时大大提高了温度控制精度和抗干扰能力。实验结果表明：该系统在0～40℃温度范圆内的控温稳定性优于±0．05℃,能够有效抑制LD波长的漂移。     

基于MAX1978的半导体激光器温控系统设计

为了保持半导体激光器工作的稳定性,设计了一种基于MAX1978的高精度温度控制系统。采用热电制冷器(TEC)作为温度补偿元件,通过外部比例积分微分(PID)补偿网络控制驱动TEC模块。该系统具有功耗低、效率高、集成度高等优点,在15℃⁴0℃控温范围内可连续调节,控温精度可达0.002℃。     

高效率DC/DC变换器——AIC1563

AIC1563是台湾沛亨半导体公司生产的高效率DC/DC变换器。它能连续输出1.5A恒流为电池充电,也可用作升压、降压及负电压变换电路。该器件的特点有;输入工作电压范围3～30V;可连续输出1.5A电流而无需散热片;转换效率高达90％;内部有±2％精度的基准电压;静态工作电流仅1.6mA;工作频率范围100Hz～100kHz;工作温度范围0～70℃。     

半导体激光器大电流脉冲恒流源的设计

设计的半导体脉冲恒流源,以高共模抑制比、低温漂的运算放大器和大功率MOSFET功率器件为主体,配以单片机控制技术与高精度D/A芯片结合,完成对二极管电流脉宽和大小的设定。同时还介绍了串联VICOR模块可调稳压源,并且根据半导体激光二极管的特性,设计了多种保护电路,极大地提高了半导体激光器电源的可靠性。本电源具有电压调节范围宽、峰值电流精度高、良好的稳定性和高低温环境适应性等特点。     

新型三端负压稳压器AIC1713系列

AIC1713是台湾沛亨半导体公司生产的新型三端负稳压器系列,输出电压:-3.3V、-4.1V及-5.0V,输出电源50mA。该系列稳压器静态电流小于22μA;温度系数-100ppm/℃;工作电压最大为-12.5V;可不接输入电容、输出电容仅需1μF;内部有短路保护电路;封装有贴片式SOT-89 及TO-92两种可供用户选择;工作温度范围为0～70℃。与 79系列负稳压器相比,具有低输出电压、耗电省、压差小特点,     

基于单片机的精密温控系统设计

本文设计了一种基于单片机的精密温控系统。该系统采用单片机为核心控制部件进行PID运算，数字式温度传感器DS18820芯片测量温度．大功率放大器OPA548驱动半导体致冷器TEC实现温度控制，精度达到±0．1℃。     

基于TEC的小型快速高精度恒温系统设计

为研究半导体器件的瞬态热学特性,研制了基于半导体加热制冷片(TEC)的小型快速高精度恒温系统;论述了基于STM32F103RBT6的加热制冷恒温系统设计,系统以微控制器STM32F103RBT6,恒温驱动电路,TEC和温度采集电路为硬件,用数字PID(proportion integration differentiation)算法实时调整输出脉宽调制信号PWM(pulse-width modulation),直到温度在预设精度范围内,从而实现恒温控制;系统采用H桥电路实现快速加热制冷,恒温驱动电路采用无源滤波器和有源滤波器构成的混合滤波器大大降低了电流纹波,提高了系统控温精度;实验结果表明,恒温系统工作稳定可靠,控制精度高,可快速加热制冷,在微小型恒温系统研制方面有一定的实用和推广价值。     

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.