车辆动态扭矩遥感测试系统设计

针对装甲车辆动力传动系统动态扭矩测试中振动和噪声干扰大、空间狭窄等问题,提出了利用无线收发装置进行扭矩遥感测试的方案.设计了某装甲车辆动态扭矩遥感测试系统,并详细介绍了该测试系统的工作原理以及硬件设计和软件设计.研制了狭小空间内近场遥测动态扭矩的测试装置,通过试验获得了某装甲车辆在不同路面工况下的实时扭矩信号.结果显示,该测试系统在扭矩测试中具有其优越性.     

采用动态扭矩传感器的双电机同步性能检测系统

针对目前对于双电机同步性能测试存在的问题,提出了一种采用动态扭矩传感器的测试方法.对双电机的转速同步性能进行检测,以保证某型转台精确稳定地运行.介绍了动态扭矩传感器的原理,并对其进行了建模分析,证明了该方法的有效性.在除振台上直接搭建测试系统,通过分析测试中所采集的波形对双电机同步性能进行检测.这套系统提高了检测的可行性,降低了虚拟平台仿真的复杂性,实现了对反映双电机转速同步性能波形的实时采集.通过实验证明该系统具有很强的实用性和可靠性.     

基于虚拟仪器的动态扭矩测试系统的研究

针对目前国内动态扭矩测试存在的问题,提出了一种新的测试动态扭矩的方法：介绍了一动态扭矩加载器装置的结构原理,用其对扭矩传感器进行了在线实时校定,基于LabVIEW测试平台,采用虚拟仪器的思想,用校定后的传感器对动态扭矩进行实时测试.这种测量方法提高了系统的可靠性和测试精度,而LabVIEW软件测试平台则减少了复杂的硬件设备,实现了对信号的实时采集显示.测量实例的应用证实了此方法的可行性和实用性.     

基于FSR的指力检测装置设计

针对脑磁图、磁共振等测试环境的特殊要求,设计了基于力敏电阻器(FSR)的指力检测装置.在该装置中,利用聚碳酸酯材料设计了将指力转换为FSR电阻改变的机械装置,通过恒流源电路将FSR电阻变化转换为电压信号,以USB6008和LabVIEW实现了数据的实时采集和显示,并对整个装置进行了静态标定和动态特性测试.测试结果表明:输出电压和施加压力近似呈指数关系;在0～15N的静态测试范围内,输出力量与实际压力的绝对误差小于0.5N,相对误差小于10%;在0～25N的动态测试范围内,绝对误差主要集中在0～2N,相对误差主要集中分布在2%～8%.装置具有较好的静态和动态特性,可用于脑磁图、磁共振等环境下指力实验.     

光伏系统功率优化器研究与设计

为了确保太阳能电池工作在最大功率点(M PP),提高光伏阵列的转换效率,研制了一种光伏系统功率优化器,介绍了系统的组成结构与工作原理.设计了降压斩波电路(BUCK电路)、驱动电路和采集电路等系统模块电路,建立了光伏系统功率测试系统,于静态和动态2种环境下进行性能测试,实验结果由测试上位机软件实时显示,结果表明:系统跟踪MPP的效率为99.38％,在2种情况下均能够准确、实时地跟踪MPP,且系统稳定,检测结果精度较高.     

基于FPGA的电机动态扭矩测量方法研究

为了提高光电式扭矩测量系统的灵敏度和系统的抗干扰的能力,设计了一种基于现场可编程门阵列(FPGA)和多路状态比较的扭矩测量系统,利用光电式多码道编码盘的旋转角测量功能进行扭矩测量.介绍了多码道码盘输出的多路信号的特征和状态细分的方法,并分析了扭矩测量的原理.硬件上采用FPGA来实现逻辑控制和数据的计数、锁存,简化了系统电路.并且把计数和状态信号传输到上位机进行处理显示,以便实时分析扭矩信号的振动.试验结果验证了该方案可应用于大型机械的动态扭矩测量系统.     

基于虚拟仪器的动态扭矩测试系统的研究

针对目前国内动态扭矩测试存在的问题,提出了一种新的测试动态扭矩的方法:介绍了一动态扭矩加载器装置的结构原理,用其对扭矩传感器进行了在线实时校定,基于LabVIEW测试平台,采用虚拟仪器的思想,用校定后的传感器对动态扭矩进行实时测试。这种测量方法提高了系统的可靠性和测试精度,而LabVIEW软件测试平台则减少了复杂的硬件设备,实现了对信号的实时采集显示。测量实例的应用证实了此方法的可行性和实用性。     

基于OpenCV的透明瓶装无色液体液位实时检测

为了实现对无色液体透明瓶装产品的非接触性检测,设计一种液位实时检测系统;系统通过工业数字摄像头实时采集产品图像,基于OpenCV开源平台,对其进行相关的预处理,检索液体区域的轮廓,提出了一种适合液位检测的包围盒取高算法,可得到液位高度;图像采集过程中利用白色背景和特殊的光源设计突显液体区域,不借助外部测量仪器对液位进行实时检测;对100副不同液位的产品图像进行测试,测量结果表明,此系统能够快速准确地获得瓶装液体的高度信息,最大相对误差0.8％,具有较好的准确性和实时性.     

高精度挠性接头刚度测试系统设计

针对挠性接头刚度测量中遇到的难点如刚度小、易变形、不易装夹定位,设计了高精度挠性接头刚度自动测量系统.利用PC机、步进电机、高精度扭矩传感器组成的系统完成了刚度测量.并使用VC编制控制系统软件,实现了数据采集和测试的自动控制.在实践中取得了较高的测试精度.     

气制动ABS调节器性能参数测试系统研究与设计

对反映气制动ABS调节器性能的静态参数和动态参数进行分析,提出以码密度进行静态参数测试,和基于xPC实时内核技术的动态数据采集系统的设计方案.针对测试系统实现的关键技术进行了研究,主要包括测试软件界面设计及参数设置、通信接口模块设计、产品合格判断子程序设计、数据实时保存与显示系统软件设计等.通过长期测试试验表明,系统采样频率可达1 kHz,完全满足行业标准要求,从而证明系统开发的有效性和可靠性.     

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).