半导体培养箱的ARM嵌入式控制系统研制

针对传统培养箱加热制冷器件能耗高、体积大且温控精度不高的特点,应用热电半导体对培养箱的温度进行调节.采用ARM920T架构的S3C2440AL处理器并配合外围设备,在Linux嵌入式操作系统上进行核心程序研发,并加入模糊自适应PID算法,以实现对培养箱温度的精确控制.试验结果表明,该培养箱的控温相对误差达到±1.1%.     

变系数PID控温系统在半导体气体传感器中的应用

提出了一种用于半导体气体传感器的温度控制电路,包含键盘输入、液晶显示、温度采集、数控调压等模块,采用变系数PID算法实现对降压模块输出电压的调控,控制气敏元件的温度.实验表明:与恒压加热和常规PID控温相比,变系数PID控温的调节时间短、超调量小,具有较强的抗干扰能力.350℃加热时,与恒压加热相比调节时间从234 s缩短到了6 s,当环境温度从30℃变化到50℃时恒压加热敏感元件温度上升9℃,而改进后温度变化不超过0.3℃,是一种很有潜力的半导体型气体传感器控温系统.     

等速升温下的微机PID控制算法

<正> 微机在过程控制和检测仪器的应用中,温度的控制通常采用PID算法,即比例——积分——微分算法,并在此算法基础上,编写控温程序。但许多场合温度的控制不只是在某一给定值上的恒温控制,而是按要求的升温速度进行等速升温控制。等速升温控制时,     

U型缸染色微机自动控制系统

前言本文介绍的是用一套 Z—8(?)单板机控制多个生产对象、可以选用多种生产工艺曲线方案并且带有 PID—PD 调节算法软件的工业过程自动控制系统。目前国内的染色设备控制部分尚未健全。虽然对于不同织物、不同染料配方都有着不同染色工艺过程和温度曲线的理论要求;但一般都是采用蒸汽加热、冷水降温,而用手动阀门的方式控制。这种手动控制方     

智能控制在温度调节仪中的应用

本文介绍一种温度控制方法,该控制方法分别采用智能PID和分段PID算法来实现,通过编制VB程序实现计算机与智能调节仪之间的双向通信。基于宇光GLCK-103 B型温度测控实验装置,计算机可对温度变送器输入的信号进行处理后与设定温度值进行比较,并进行P、I、D参数运算,送给智能调节仪进行调节,输出信号对可控硅调压模块进行控制,改变加热功率以达到控制温度的目的。最后,验证了智能PID算法和分段PID算法在温度调节应用中的有效性。     

基于神经网络的硫化仪温控改造

硫化仪是一种广泛配备使用的橡胶检测仪器,其传统机型多采用固定参数的PID控制,存在升温曲线多震荡及控温速度较慢的问题;并且对于固定参数的传统控制方法来说,在不同环境条件下的控制匹配效果不同。现采用PSO粒子群算法改进BP神经网络,用神经网络计算、控制PID参数进而控制模腔。实验结果表明：采用BP-PID控制的硫化仪模腔达到同样150℃的设定温度,比传统PID控制的模腔加热速度提高36.5%;且针对不同设定温度,此控制方法升温曲线波动平均降低22%,具有很好的普适性。     

台车式退火炉PLC控制系统的优化设计

针对原台车式退火炉控温系统超调大、信息监控实时性差以及运行可靠性低等问题,应用西门子S7-300 PLC控制系统进行优化设计,包括温度控制、燃烧过程控制、压力及电气联锁控制、上位机管理系统等.温度是系统控制中的关键参数,根据专家的经验知识,通过PLC程序对控温算法进行优化设计.同时利用STEP7软件指令自主研发程控脉冲燃烧分频程序,保证控温的精确性和在炉内分布的均匀性.实际运行结果表明,系统性能稳定、控温精度高、硬件成本低,很好地满足了工艺需求.     

冻干试验机温度自适应模糊PID算法研究

将模糊控制理论应用于冻干试验机的温度控制系统中,有助于提高温度响应曲线的跟随性及加快反应时间,从而可以提高温度的控制精度。通过PID控制与参数自适应模糊PID控制的对比的MATLAB仿真实验,获得了调节时间有明显改善的参数自适应模糊PID控制器算法;对真空冷冻试验机系统的近似模型进行了定量分析,并结合实践经验,给出了模型的数学表达式。应用新研制的控制器算法,对具有非线性、大滞后特征的冻干试验机温度系统具有很好的控制作用,弥补了传统的PID控制的不足。     

基于PLC的内模PID窑炉温度控制系统设计

在工业生产过程当中,PID调节是经典控制理论中最典型的闭环控制方法,但是对于非线性大时滞大惯性的陶瓷窑炉温度控制系统.传统PID控制的效果不佳.本文简单介绍了基于内模控制原理的PID参数整定方法,详细地阐述了基于内模PID的陶瓷窑炉温度控制在西门子PLC S7-200中的算法实现.通过MATLAB软件仿真,将内模PID的陶瓷窑炉温度控制效果与传统PID控制进行比较,论证了其优良特性.     

一种基于STM32和ADS1248的数字PID温度控制系统

介绍了一种基于STM32和ADS1248的温度控制系统.系统中以Pt100热敏电阻器作为温度传感元件,以热电制冷器作为温度控制元件,采用数字PID算法对温度进行控制.该系统电路设计简单易于实现,控制灵活性大.实验结果表明:该系统可以有效实现温度的控制,其控温精度可达±0.1℃.     

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。     

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.     

Editorial: Special issue on recent advances in hybrid control theory and applications

正The demands of a rapidly advancing technology for faster and more accurate controllers have always had a strong influence on the progress of automatic control theory.In recent years control problems have been arising with increasing frequency in widely different areas,which cannot be addressed using conventional control techniques.The principal reason for this is the fact that a highly competitive economy is forcing systems to operate in regimes where     

Information for Authors

正Aim The Journals of Zhejiang University-SCIENCE(A/B/C)areedited by the international board of distinguished Chinese andforeign scientists,and are aimed to present the latest devel-opments and achievements in scientific research in China andoverseas to the world’s scientific circles,especially to stimulateand promote academic exchange between Chinese and for-eign scientists everywhere.     

Enhancing a leaf radiative transfer model to estimate concentrations and in vivo specific absorption coefficients of total carotenoids and chlorophylls a and b from single-needle reflectance and transmittance

The relative concentrations of different pigments within a leaf have significant physiological and spectral consequences. Photosynthesis, light use efficiency, mass and energy exchange, and stress response are dependent on relationships among an ensemble of pigments. This ensemble also determines the visible characteristics of a leaf, which can be measured remotely and used to quantify leaf biochemistry and structure. But current remote sensing approaches are limited in their ability to resolve individual pigments. This paper focuses on the incorporation of three pigments—chlorophyll a, chlorophyll b, and total carotenoids—into the LIBERTY leaf radiative transfer model to better understand relationships between leaf biochemical, biophysical, and spectral properties.Pinus ponderosa and Pinus jeffreyi needles were collected from three sites in the California Sierra Nevada. Hemispheric single-leaf visible reflectance and transmittance and concentrations of chlorophylls a and b and total carotenoids of fresh needles were measured. These data were input to the enhanced LIBERTY model to estimate optical and biochemical properties of pine needles. The enhanced model successfully estimated reflectance (RMSE = 0.0255, BIAS = 0.00477, RMS%E = 16.7%), had variable success estimating transmittance (RMSE = 0.0442, BIAS = 0.0294, RMS%E = 181%), and generated very good estimates of carotenoid concentrations (RMSE = 2.48 µg/cm², BIAS = 0.143 µg/cm², RMS%E = 20.4%), good estimates of chlorophyll a concentrations (RMSE = 10.7 µg/cm², BIAS = − 0.992 µg/cm², RMS%E = 21.1%), and fair estimates of chlorophyll b concentrations (RMSE = 7.49 µg/cm², BIAS = − 2.12 µg/cm², RMS%E = 43.7%). Overall root mean squared errors of reflectance, transmittance, and pigment concentration estimates were lower for the three-pigment model than for the single-pigment model. The algorithm to estimate three in vivo specific absorption coefficients is robust, although estimated values are distorted by inconsistencies in model biophysics. The capacity to invert the model from single-leaf reflectance and transmittance was added to the model so it could be coupled with vegetation canopy models to estimate canopy biochemistry from remotely sensed data.     

Mr. Twinn’s bombes

This article discusses the history and design of the special versions of the bombe key-finding machines used by Britain’s Government Code & Cypher School (GC&CS) during World War II to attack the Enigma traffic of the Abwehr (the German military intelligence service). These special bombes were based on the design of their more numerous counterparts used against the traffic of the German armed services, but differed from them in important ways that highlight the adaptability of the British bombe design, and the power and flexibility of the diagonal board. Also discussed are the changes in the Abwehr indicating system that drove the development of these machines, the ingenious ways in which they were used, and some related developments involving the bombes used by the U.S. Navy’s cryptanalytic unit (OP-20-G).