基于能量自搜集的智慧城市无线感知节点供电系统研究

无线传感器网络技术的发展与推广,受到供电问题的制约。本文研究一种供电系统,为解决无线传感网络的供电问题提供一种可行的参考方案。本文研究了一种基于能量自搜集的智慧城市无线感知节点供电系统,该系统采用多晶太阳能电池板搜集了光能,采用温差发电片搜集了热能,以压电陶瓷为基础制作的悬臂梁实现了对振动能的采集,并将搜集到的能量转化为稳定的直流电能并进行智慧化存储管理,为本系统的无线传感器模块供电。该系统最短可在177秒内将超级电容充电至4V,或将搜集到的能量稳定地储存到锂电池中,从而为无线感知节点持续供电。结论：本文所研究的系统在无线传感器网络技术领域具有广阔的应用前景。     

基于无源技术的无线传感器网络节点设计

电源在整个无线传感器网络系统中具有极其重要的意义,为了满足系统为微型传感器节点供电的需求,本文设计了采用充电泵实现超低压启动、双电容蓄能的微弱能源采集电路。该电路能够在低温差条件下为蓄能电路积累能量,实现低温差环境下的微弱能量采集,并能够根据无线传感器网络节点间歇性工作的特点,快速做好供电准备。实验结果表明,系统具有能量收集效率高、传输距离较远等优点,有效地解决了无线传感网络节点能源供电的问题,具备较高的实用价值。     

农用无线传感器节点基于混合能量收集和利用的自供电系统设计

智慧农业的实现基础是能够高效可靠地采集并传输农田环境信息。农业生产环境具有复杂、影响因素多、异质性大等特点,这对传感器节点的适应性及供电系统提出更高的要求。本研究创新性地设计了一种农业环境微能量收集系统。该系统将太阳能、土壤温差能和微型风能混合收集,并利用所设计的一体化发电系统实现对无线传感器网络节点自供电。采用高效的电能管理电路实现了各能量的互补利用,达到了通过对混合环境微能量的高效收集来为无线传感器节点稳定供电的目的。文中针对多种能量收集策略、最大功率点跟踪技术以及阻抗匹配功能实现等问题进行了分析研究,并总结了目前混合能量收集技术的现状及发展趋势。     

无线传感器网络节点能量供应系统设计

在影响无线传感器网络的生命周期的众多因素中,节点的能量是其中最为重要的.节点的功耗、布撒环境以及具体应用等因素,都对节点的能量供给有重大影响.本文分析了当前基于能量挖掘的节点能量供应系统,并提出了改进的无线网络传感器能量供应系统,实现了利用环境能量为无线网络传感器节点永久供电.     

Research of cooperative transmission technology based on H ∞ filter energy prediction

研究了一种适用于分布式移动无线传感器网络数据传输基于能量预测的协作通信技术.针对无线传感器网络,协作数据传输技术难以有效解决无线网络动态拓扑结构、带宽和能量受限等问题,建立了一种基于H∞滤波器相邻节点剩余能量预测的分布式中继选择机制,并在此基础上建立数据协作传输技术.该技术充分利用无线信道的广播特性,首先根据H∞滤波器预测节点剩余能量,然后根据剩余能量值选择最大者作为协作节点,最后根据无线信道质量在放大重传和解码重传机制之间进行自适应调整.数学分析表明,H∞滤波器可以准确地预测节点的剩余能量,同时该协作传输技术能够显著提高无线传感器网络的资源利用率和系统吞吐率,有效延长网络寿命.     

基于Ad-hoc和GIS辅助的无线传感器网络定位

针对现有无线传感器网络自定位算法难以脱离大量的静态信标节点的问题,利用Ad-hoc的自组织特性,提出了一种基于分簇并只以簇头节点为移动信标的动态无线传感器网络自定位算法.该算法通过簇内动态混合定位的方式,有效提高了盲节点的定位精度.同时设计和实现了一个基于ArcGIS Engine的动态目标定位监控系统,利用GIS辅助将相对定位与基于地图环境下的绝对定位相结合,进一步提高了无线传感器网络的定位精度.MATLAB仿真实验以及系统实例表明了算法的实时性、有效性和系统的可行性.     

智能变电站辅助监控系统中独立节点的能量自供给技术研究

对智能变电站中常见环境能量源的收集技术和特点进行了介绍,同时根据监测传感器节点的功耗特征设计了相应的能量自供给电路。通过LTspice仿真软件模拟搭建了自供电节点的能量收集和功耗模型,进行了仿真分析。仿真结果表明,采用变电站环境中的太阳能、温差能和风能收集技术,在现有的技术条件下可以做到一些低功耗无线传感器节点的能量完全自供给,避免了因更换节点电池而引起的设备频繁停电维护。     

具有温差能量收集功能的胎压传感器电路设计

胎压传感器是一种在汽车上应用多年的无线传感器,但是电能供应一直是制约该传感器使用寿命的一大瓶颈。提出了一种收集环境中热能的方法,设计了一种能量收集电路,实现了胎压传感器的无线无源自供电。利用温差发电器件(TEG)将轮胎内部积蓄的热能转换为电能,并基于LTC3108电源管理芯片设计了一种超低压电能收集电路。实验表明,所设计的电路可以收集低至100 mV,10 mA,1 W能量,并经过一段时间的积累之后成功驱动胎压传感器。     

基于能量和距离的无线传感器网络分簇算法

无线传感器网络由大量能量有限的传感器节点组成,这些节点一般都是靠电池供电.如何在这种情况下,尽量延长网络的生存周期是研究的热点问题.基于分簇的无线传感器网络路由算法不论是在网路生存周期方面,还是在数据融合方面都比自组织算法表现出了很大的优势.文中提出了一种基于能量和距离的ED-LEACH(Energy and Distance-LEACH)改进算法,在簇头的选举和簇的生成两个阶段都综合考虑了能量和距离这两个因素.仿真表明该算法较LEACH算法显著地延长了网络的生存期.     

基于自供电的无线传感器网络MAC层协议研究

针对自供电的无线传感器网络,提出了一种新的MAC层协议DFSA（动态帧时隙ALOHA）,该协议对能量进行系统管理。仿真结果表明在具有能量收集能力的传感器网络中,DFSA能够充分利用节点的能量收集能力,实现网络能量充分利用,在保证较高的传输效率下获得最高的信道利用率,同时提高了数据传输的可靠性。     

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。     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

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.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.