农田环境监测系统设计与实现

针对农业生产的自动化管理需求,介绍了ARM与Zig Bee技术相结合设计农田环境监测系统的方法。硬件部分采用Zig Bee外接传感器设计环境数据采集节点,采用S3C2440处理器和CC2530设计协调器网关,其中CC2530与ARM之间采用SPI口进行数据通信。软件部分基于IAR平台结合Z-Stack协议栈构建Zig Bee无线监测网络,用于采集并传输影响农作物生长的现场环境信息,数据在基于ARM与Zig Bee技术相结合而开发的网关节点处实现汇聚,最终通过串口发送到基于VC++6.0与数据库技术开发的上位机监测系统。经测试,网关节点能实时接收传感器节点的数据,并通过串口成功上传到上位机监测系统,实现实时数据监测、动态分析、历史查询和异常报警功能,系统具有较好的稳定性和实用性。     

基于Zig Bee无线传感器网络技术的管道监测系统

为了改进传感器铺设和布线的烦琐,通过Zig Bee采集数据,无线网络技术实现实时远程的管道安全监测。采用无线收发CC2430芯片配合MSP430,设计了基于无线传感器网络技术的管道安全监测系统,通过实验验证了Zig Bee技术在管道安全实时监测中应用的可行性。     

基于ZigBee的太阳能景观灯系统的设计

为利用Zig Bee监测太阳能系统和景观灯系统,设计一种基于Zig Bee的太阳能景观灯系统,充分提高光能,电能的效率。结合系统设计特点除协调器其他所有无线网络系统中半功能设备和全功能设备都有太阳能和景观灯,通过充过放等保护电路后由CC2530采集数据并通过无线的传输方式传给协调器最后由PC端实时数据。     

基于WSNs的农作物生理参数检测系统设计

获取农作物的茎秆与果实直径、叶绿素含量、植物茎流等生理信息来指导农业的施肥与灌溉等具有重要的意义.针对传统农业中植物生理参数实时检测方法的不足,设计一种新型的基于无线传感器网络(WSNs)农作物生理参数检测系统.该系统的数据采集端使用IAR平台搭建Zig Bee WSNs,采用基于CC2530芯片的无线传感器节点采集并发送植物的各项生理参数.系统的远程传输端采用基于ARM9的CDMA DTU模块将数据通过CDMA2000和Internet网络发送到远程检测中心,检测中心通过LabVIEW和SQL Service联合编写的上位机软件可以实时显示数据和查询历史数据,并可对各项数据指标进行分析判断.实验结果表明:该系统精准度较高,数据传输稳定,达到设计要求.     

基于Zig Bee的无线传感器网络大气监测系统设计

大气污染问题突出且日益严重,对大气环境实时准确地监测具有重大社会意义。现有的监测手段实时性差、维护困难,难以满足实际需求。针对上述情况,设计了一种基于Zig Bee技术的大气监测系统,并详细阐述了系统的整体框架结构和实现方案。系统包括无线传感器网络和远程监测中心2个部分。其中无线传感器网络包括传感器节点和网关节点。传感器节点以CC2530为核心搭建,负责采集大气环境数据并通过多跳方式将数据实时发送至网关节点;网关节点以LPC2138为核心搭建,负责汇总传感器节点的数据并通过GPRS实现与远程监测中心的通信。远程监测中心使用在Microsoft Visual C++6.0环境下编制的监测软件,通过网络模块完成数据接收、显示及存储,为用户提供一个友好的人机界面。     

基于Zigbee和GPRS的多参数水质监测系统设计

针对传统水质监测存在的实时性差、覆盖范围窄、网络布局困难等问题,设计出一种基于Zigbee无线传感网络和GPRS技术的远程实时水质监测系统.文中重点阐述该系统的硬件设计和软件实现过程.该系统将水质传感器采集的各项参数传送给CC2530芯片后,经Zigbee网络发送给网络协调器,再通过GPRS无线通信模块SIM300传送到Internet或移动终端,最后用户可通过PC机或手机终端查看水质参数信息,实现了水质信息的远程实时监测.实验应用表明,该系统监测范围广、使用方便、快捷,具有较为广阔的应用前景.     

基于Zig Bee技术的智能车无线控制系统开发

针对连续位置数据采集的需要,开发了可移动智能控制系统,实现对智能车周边环境的实时监测。该系统由上位机系统、通信系统和下位机系统三部分组成。上位机由PC机构成;通信系统由2个ZigBee模块构成;下位机系统由智能车、GPS模块、ARM开发板构成。该系统基于Zig Bee 2007协议的点对点通信,以CC2530芯片为核心、以智能车为载体、以ARM微处理器为下位机主处理器。开发的系统减少了Zig Bee静态节点的数量,从而降低监控成本、静态固定采集点的使用、更方便地进行全方位准确监控。     

基于ZigBee无线传感网络的粮库粮情监测系统的设计

针对粮库环境检测中监测点多且分散的情况,设计了一种基于Zig Bee无线传感网络的小型粮库粮情监测系统。详细阐述了以CC2530为核心的终端节点、协调节点的软硬件设计对现场环境的温度、湿度等多种参数进行监测,通过协调节点将现场参数上传至上位机实现粮库内的多点监测和实时监控。     

矿产开发设备运行状态远程监测系统设计与实现

针对青海矿产设备运行状态监测困难、故障诊断不及时等问题,使用Zig Bee CC2530开发板、霍尔电流传感器及温湿度传感器等构成无线传感器监测节点,组成无线传感器网络短程通信,并通过WSN/GPRS网关节点实现远程通信,用户最终可通过Web系统对矿产设备的运行状态进行监测和管理。测试结果表明,系统采集数据准确,数据传输可靠稳定,人机互动界面简洁,能够满足远程设备运行状态监测的需求。     

基于ZigBee和Internet技术的远程抄表系统的设计

设计并实现了一种基于Zig Bee和Internet的远程抄表系统。感知层利用智能传感器技术,实现对电压、电流、频率、功率、电能等用电信息的采集。传输层采用Zig Bee短距离通信技术实现对节点信息的汇聚,并利用嵌入式以太网模块实现Zig Bee网络数据到Internet数据的转换,通过广域网路由器接入Internet。应用层通过信息管理系统实现远程抄表与信息管理。测试表明,该系统达到了预期的效果。     

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).