并联传感器系统压力传感器故障诊断系统设计

在工业生产过程中电子皮带秤普遍采用多个称重传感器输出信号的并联方法,而该方法对多个称重传感器无法独立采集同时无法准确判断故障;应用TI公司MSC1210单片机最小系统和信号分离器,设计一种并联传感器系统压力传感器故障诊断系统,实现多个称重传感器并联应用时的独立采集;发明一种皮带秤称重传感器累计量校准方法,将不断变化的累计量转换成定量值实现并联传感器系统压力传感器故障诊断;结果表明该系统较好实现多个称重传感器的独立采集和故障传感器判断,为皮带秤等计量装置并联传感器系统的技术升级提供有效手段。     

基于温度信号的传动系统在线监测装置的研制

针对我国风力发电机齿轮箱状态监测与故障诊断发展的实际需要,利用温度采集技术和虚拟仪器技术,专为传动系统的状态监测提供了一套应用解决方案.建立了传动系统模拟装置,模拟了风力发电机齿轮箱的工作状态.研制了基于温度信号的在线监测装置,设计了基于AD590温度传感器的多路信号采集电路,并采用Labview进行软件编程.使用基于温度信号的在线监测装置对传动系统模拟装置进行了温度信号采集,实验结果表明,在线监测装置可以实现对传动系统的在线状态监测,为实验室条件下传动系统状态监测与故障诊断技术的研究提供了有效的技术支持.     

基于WSN的天然气管道压力预警监测仪装置设计

天然气管道的压力预警监测仪装置设计是实现天然气在管道中安全传输的关键。提出一种基于无线传感器网络(WSN)的天然气管道的压力预警监测仪设计方法,设计了天然气管道压力信号采集和预警识别算法,采用最小方差响应不变波束形成进行压力信号识别。进行监测仪系统硬件模块设计,设计压力传感器运算放大器电路,基于WSN实现天然气管道压力预警监测仪的改进设计。系统测试结果表明,该监测仪表装置能准确采集天然气管道压力信号,能提高对天然气管道压力信号的采集识别性能,为实现天然气管道压力预警监测仪提供准确的数据基础,监测仪装置能实现对管道内的各种参数的全面、实时、动态的监控。     

传感器在压力开关综合测试装置中的应用

针对压力开关生产过程中对作动压力、接触电阻、同步等性能的检测要求,利用传感器等技术设计开发了一套综合测试装置,系统采用了分布式、多通道信号实时采集与处理方法,每个测试控制单元以单片机为核心,独立完成检测控制任务,再由多个测试控制单元形成一套完整的检测系统.试验结果表明,该装置满足检测精度及生产节拍的实际要求,实现了综合性能的在线自动检测和定量分析.     

嵌入式系统在军用电子设备故障诊断中的应用

电子装备现有的故障诊断系统一般无法完成装备工作过程中的实时在线状态监测。利用多种非接触式的传感器信息融合技术、以太网网络通信技术,设计了现场级嵌入式状态监测系统,采用嵌入式微处理器S3C44B0X构建最小系统实现实时地对系统各个重要部分进行信号采集和在线状态监测,为在线智能故障诊断系统提供诊断信息。     

NAMUR型速度传感器信号采集电路的设计

为了准确获取NAMUR型速度传感器信号,设计了一种基于PIC18F2480单片机的信号采集电路,并给出了该电路的软件设计流程。该信号采集电路可采集到0~600 Hz的频率信号,并可在线监测传感器断线、短路或正常工作等状态。     

基于SEP4020的嵌入式无线动态称重系统

设计一种基于嵌入式系统的无线汽车动态称重系统.采用ARM7处理器SEP4020、实时操作系统(RTOS)、图形用户界面(GUI)设计一台手持式终端,通过2.4GHz无线通信模块与单片机数据采集系统建立通信,单片机数据采集系统通过仪表放大器和模数转换芯片Max186采集压力传感器信号传送给手持终端.实践证明该系统是切实可行的.     

矿井动力灾害实时在线监测系统设计

针对目前煤矿深部动力灾害的监测主要依赖于在线采集装置,无法实现数据的并行和快速采样的缺点,设计了一套动力灾害实时在线监测系统。该系统利用声发射、瓦斯、应力等传感器实时监测矿井动力灾害发生过程中煤岩释放的应变能及瓦斯浓度、煤岩应力参数,利用监测站实时采集、处理各种传感器信号,通过上位机数据管理软件对特征参数指标变化规律进行有效分析、结果预警等,从而实现了对动力灾害的连续动态监测。实际应用结果证明了该系统的可靠性。     

容性设备在线监测装置现场校验系统的开发

针对变电站各类高压容性设备在线监测装置的现场校验,提出一种新的容性设备在线监测装置校验方法并研制出相应的校验系统,校验项目涉及：全电流,阻性电流,容性电流,介损因数。该校验系统由信号采集无线发送装置和检定装置组成,信号采集无线发送装置将现场变压器二次侧电压作为参考电压通过无线传输方式传入检定装置,检定装置内的控制模块根据预设指令及参考电压信号控制内部数控交流电流源生成一路与电网电压频率同步,幅值和相位可调的电流信号。将该电流信号耦合到容性设备在线监测装置电流传感器,通过比较耦合前后装置相应监测量变化值与校验系统设定值的误差,达到校验容性设备在线监测装置有效性的目的。实验证明,该校验系统输出电流指标满足现场校验的要求。     

嵌入式电子装备的在线状态监测研究

电子装备现有的自动测试设备一般无法完成装备工作过程中的实时在线状态监测。该文利用多种非接触式的传感器信息融合技术、无线RS-232串口通信技术，设计了现场级嵌入式状态监测系统，采用嵌入式微处理器S3C44B0X与μCOS –II实时操作系统实现同步、并行地对系统各个重要部分进行信号采集和在线状态监测，为视情维修奠定了基础，为进行切实有效的超前预防维修，使装备始终处于良好的战备状态提供了保障。     

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).