一种基于超高频RFID的无线无源压力传感器

电力设备在长期运行中,受环境影响,可能会发生失压、形变现象。针对这种现象,设计了一种基于UHF RFID的无线无源压力传感器,能够在不接触电力设备的情况下获得设备的表面压力信息。基于UHF RFID的压力传感器标签主要由阻抗自适应RFID芯片、UHF频段RFID偶极子天线、金属极板和支撑弹簧构成。电力设备的形变会导致安装在设备上的金属极板与偶极子天线的相对位置变化,导致RFID天线的阻抗变化,RFID芯片内部会通过自动调节输入阻抗电容以匹配RFID天线阻抗的变换。通过检测RFID芯片内部匹配阻抗的电容值,可以推出电力设备的形变情况,形成一一对应的关系,从而实现无线无源压力传感功能。     

基于AS3992芯片的远距离RFID读写器设计

介绍了一种基于AS3992芯片的远距离RFID读写器设计。通过AS3992内部集成的模拟前端和协议处理系统,配合基带的MCU控制,实现了在通信频率840MHz~960MHz内发射功率可调、天线接口可切换等实用功能。为了达到更远的传输距离,使用了多种阻抗匹配网络对微带线阻抗进行微调,且对输出功率加以检测,有效防止了盲目增大发射功率导致接收干扰而影响识别距离的问题。设计了4个天线接口,扩展了读写器的应用距离,同时减少了单天线的盲区,降低了误码率。     

无源UHF超高频标签天线设计与研究

无源UHF频段RFID技术信号传输速度快,覆盖距离远,通过与互联网、通讯等技术相结合,可实现全球范围内物品的跟踪与信息共享。该技术由射频模拟前端电路、控制逻辑电路等组成的无源UHF超高频射频识别标签系统,由外接天线与读写器完成通信,天线既要与识别标签相匹配,又要与读写器较好地通信,天线决定了标签是否能正常工作,同时也决定了信号传输的距离。为此,通过研究天线的匹配阻抗、形状尺寸与大小,以及频带的设计,探索出了低成本、高可靠的天线设计方案。     

功率自适应超高频RFID读写器系统设计

以基于STM32和RMU900+的物联网工程读写器为基础平台,将雨量传感、温度传感和雷达探测等模块引入到RFID系统中,并制定可独立调节和全网集中调节的射频模块发射功率自适应控制策略,在确保可靠识读的同时,降低了系统功耗,延长了读写器的工作寿命。该设计可为有高可靠性要求的同类应用系统提供参考。     

集装箱RFID系统的传播损耗模型及其性能分析

根据集装箱射频识别(RFID)系统无线电波传播特性,建立读写器与电子标签之间电波传播损耗的预测模型。利用该模型对集装箱射频识别系统的性能参数进行仿真分析,得到最大识别距离与发射功率、接收灵敏度以及读写可靠性与识别距离和发送功率之间的关系曲线。研究结果表明,集装箱RFID系统天线不宜采用TE极化方式,在RFID系统设计和应用中,应尽量减小多径传播引起的衰落。     

多标签多协议RFID读写器设计

近年来,RFID(射频识别1技术发展迅速,应用日益广泛.本文设计了一种基于TRF7960的具有多协议自适应功能的RFID读写器,该读写器具有防碰撞、多标签识读功能,具备多种接口和图形化人机界面.本文从硬件和软件两方面阐述该读写器的设计.系统硬件结构包含CPU模块、读写器模块和接口.软件方面,描述了TRF7960驱动、读写器控制程序和多协议自适应的实现.最后,结合实际展望了该读写器的应用前景.     

新颖的物联网RFID传感系统防冲突算法

基于超高频射频识别(RFID)技术构建物联网系统往往需要将多个读写器同时工作于同一区域,这种多读写器环境势必会造成多读写器冲突,严重影响系统的性能。针对常用的反向散射耦合方式,选取信干比作为系统通信质量的度量,提出基于快速功率控制和退避机制的防多读写器冲突算法。读写器依据信干比情况,动态调节自身发射功率,在保证读写器读写距离的同时,减少信号覆盖区域的冗余,实现防冲突。考虑到发射功率调节至最大时,读写器仍可能无法获取目标信干比,引入了退避机制,使读写器主动降低发射功率,其退避时间映射于目标信干比迭代比例。实验结果表明,读写器能够根据功率控制算法,动态调节发射功率并快速收敛,提高了系统的实时性和可靠性。退避算法的设计提高了读写器信道争用的公平性,而且大大降低读写器功耗,这对移动/手持读写器尤为重要。该防冲突算法有效地最小化信号覆盖区域的冗余,实现防多读写器冲突,同时能够保证读写器的目标识别距离,提高了标签识别率。     

SAW温度传感器测温系统中的天线设计

为实现对电力设备接点的测温,设计了基于声表面波的无源无线温度传感器的测温方案,具体研究其天线设计以及天线和传感器的匹配方法。方案中读写器天线采用平面倒F天线,传感器天线采用法向模螺旋天线。通过仿真分析和优化设计使得两款天线的谐振频率均为915 MHz,驻波比均小于1.5,达到了系统要求。通过改变馈点位置实现了平面倒F天线的匹配,法向模螺旋天线的匹配采用了Smith v2.0软件,最终两款天线的阻抗均为50Ω。     

RFID技术在自动销售系统中的应用与实现

简单介绍了RFID的基本原理,应用该技术设计了自动销售系统:包括电子标签的天线、数据格式和基本功能的设计;读写器的平板天线,读写器的硬件和软件系统的设计;销售管理系统的设计.为了简化读写器的硬件,采用了DSP技术,用软件方式实现了射频无线信号的调制与解调.应用表明:系统适用范围广,处理速度快,漏识别率低.     

基于阻抗调制的RFID系统设计

随着RFID技术在我国的不断发展,它已经成为新兴产业的热门话题;为实现短距离、高精度的传输,经过研究,一种低成本高精度、高适用型载频为3.6864M的RFID无线识别系统的制作方法刚好满足要求,通过基于阻抗调制实现无源RFID读写器的方法,详细描述RFID读写器基本组成和基于单片机的RFID读写器设计;在这基础上分析了RFID读写器信令协议流程的处理原理及实现,并在实际的读取标签、一卡通等应用中取得较为理想的效果.     

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.     

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.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

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Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate