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关键词： Localization   radio frequency identification (RFID)   received signal strength indicator (RSSI)   rotating synthetic aperture radar (RSAR)   synthetic aperture radar (SAR)  

摘要： Thanks to the vigorous development of smart logistics and warehouse applications, many scholars have made outstanding contributions to indoor object positioning, among which indoor positioning algorithms mediated by radio frequency identification (RFID) systems are particularly prominent. However, the phase information of RFID has the characteristics of high precision, and the state-of-art algorithm generally uses phase information to achieve localization. Inspired by the synthetic aperture radar (SAR) method that uses phase information, this article first proposes a rotating SAR (RSAR) method for harnessing received signal strength indicator (RSSI) information. This method establishes a functional relationship between RSSI information and angle and virtually synthesizes reader antenna arrays at different angles at the same point by rotating the reader antenna. By combining the RSAR method using RSSI information with the SAR method using phase information, a 3-D positioning system with mobile robots as the carrier is proposed. After that, this article proposes a position estimation algorithm named sort cluster algorithm with threshold (SCWT) to improve positioning accuracy. Finally, we evaluate the performance of the three aspects of our proposed algorithm through multiple experiments. First, experiments show that the RSAR method can achieve high-precision positioning. Second, the RSAR method and the SAR method are independent of each other when realizing 3-D positioning. Third, comparative experiments show that the time complexity of the proposed position estimation algorithm is more dominant.

关键词： 无线射频识别   深度学习   机器学习   动作识别  

摘要： 射频识别(RFID)技术是一种无接触的自动识别技术。它能够去识别目标物体并获得其数据,不需要接触,不需要他人干预,能在极端恶劣的条件下工作。RFID技术识别目标不仅速度快且能够同时识别多个电子标签,随着科学技术的快速发展,RFID相关理论的丰富和发展,如今RFID技术被应用在生活的各个方面,最近的一些研究将标签进行穿戴和非穿戴进行检测动作,然而由于噪音干扰、环境干扰、传输距离相对较近、被物体阻挡后失效率比较高等原因,导致目标识别准确率降低。因此考虑穿戴式和非穿戴动作识别非常重要。针对目前基于RFID动作识别所面临的问题,本文进行了以下工作研究并取得了一定研究成果: (1)针对穿戴式RFID的学习状态识别,本文提出了一种新的无源RFID网络学习动作识别系统,并命名为LD-identify。LD-identify可以通过获取相位和信号强度来实现学习动作识别,同时还可以有效地保护个人隐私,而且解决了因设备价格昂贵或环境要求较高的问题。通过在实验者帽子的背面粘贴两个电子标签,系统可以获取不同动作的相位和信号强度,构建分类网络模型并利用深度学习技术,可以有效地辨别出实验者的3种不同动作:抬头低头、左右摇头、前倾后倾,而且准确率也很高。为更进一步检验该系统的性能,本文在各种情景下对6名实验者进行了动作识别,结果表明,该系统能够准确地辨识出实验者的各种不同动作,而且通过采用卷积神经网络的分类模型,能够更高地获得动作识别准确率。经过精确测量,准确率达到了95.5%以上。 (2)针对非穿戴式RFID的学习状态识别,本文提出了一种基于无源RFID的课堂动作识别系统LD-recognition,解决了由于班级人数较多,教师很难同时关注到每位同学的学习状态的问题。LD-recognition将标签粘贴在课桌的右侧挡板上,去获取四种不同动作下的数据,为了减少噪音干扰首先对数据进行小波阈值降噪,然后对降噪后的数据进行归一化处理,最后提出一种多通道的注意力机制的图卷积神经网络进行深度学习。通过识别学生举左手、举右手、低头瞌睡、拿书四种动作来判断学生的学习状态。系统利用一种多通道的注意力机制的图卷积神经网络(ATGCN)对动作的相位和信号强度进行深度学习并进行识别。LD-recognition从不同距离、不同实验者、不同网络模型等方面来验证动作的准确率,实验结果表明LD-recognition系统识别准确率较高,平均达到96.9%。

关键词： Paper   simulation   design   antenna   reflection coefficient   tag   communication  

摘要： The effect of antenna design modification, paper substrates and relative electrical permittivity of background materials on the reflection coefficient of UHF RFID antennas was studied. Simulation software was used to modify the design and calculate the reflection coefficient of the antennas. By modifying the coupling of the dipole with the induction loop of the antennas, a reduction of the simulated reflection coefficient was achieved compared to the commercial antenna. The positive effect of antenna modification was also confirmed by measuring the reflection coefficient of antennas printed on paper by thermal transfer printing, placed on extruded polystyrene and particle board. The reflection coefficient of the modified antennas was lower when placed on extruded polystyrene, whose relative electrical permittivity was lower than particle board. After installing the memory chip to the antennas printed on paper and paperboard, the identification, reading and recording range of passive UHF RFID tags were measured after they were placed on thicker paperboard, extruded polystyrene and particle board. The positive effect of antenna modification on improving the communication quality of passive UHF RFID tags placed on background materials with a relative electrical permittivity of 2.4 to 6.7 was confirmed.

关键词： Backscatter   Modulation   Protocols   Signal to noise ratio   Radiofrequency identification   Amplitude shift keying   Quadrature amplitude modulation   ASK   backscatter communications   PSK   pulse shaping   QAM   RFID   single sideband modulation  

摘要： The growing interest in backscatter communications as a low-powered solution in various fields necessitates pushing the envelope of current backscatter systems in multiple frontiers, among which is spectral efficiency. The increase in spectral efficiency can drive real-time applications such as augmented reality. In most of backscatter-system applications such as radio-frequency identification, backscatter modulation is implemented using binary schemes realized with square pulses, which are not spectral efficient. To address the spectral efficiency concern, this article reviews-with a scope limited to prototyped systems-some of the existing works in the literature that pertain to increasing the spectral efficiency of backscatter systems. The prototyped systems can be grouped-based on the implementation technique used-into three groups: High-order modulation, single-sideband modulation, and pulse shaping. Based on the current trends and studied literature, the article concludes with discussions on some future directions and open-ended research problems such as optimal pulse shaping, the use of artificial intelligence, multi-carrier modulation, and agile modulation;which are all aim for overcoming the spectral-efficiency limit of contemporary backscatter systems.

关键词： 射频识别   人机交互   轨迹追踪   全息图  

摘要： 随着智能设备的广泛普及,越来越多的应用通过人机交互的方式来提供各种服务,实现更加自然的交互方式也成为人机交互相关应用设计的初衷。由于射频识别(Radio Frequency Identification,RFID)设备能够提供更加细粒度的标签位置信息,将标签部署在物体之上可获得物体的位置和运动轨迹,使得将普通的物体转化成智能的人机交互设备成为可能。特别的,在实现手写轨迹追踪上,虽然已经存在比较成熟的设备(如触摸屏、Apple Pencil等),但是他们大多需要较高的硬件成本并且只能在特定的智能设备上进行工作。而基于RFID的手写轨迹追踪方案具有造价低、可扩展性强和部署方便等优势,因此将此类系统推广到智能家庭、教室和办公室等场所至关重要。本文对基于RFID的手写轨迹追踪技术进行了研究,设计了一个手写板系统RF-Board,在对RFID相位信息与距离变化的关系进行了理论研究的基础上,使用现有的RFID设备制作了原型系统。首先将四个小型微带天线布置在木板下方,当用户使用贴有双标签的物体作为笔在木板上移动时,阅读器通过天线采集标签移动时的相位信息,然后使用两个定位算法分别对靠近笔尖和笔尾处标签进行定位,最后结合标签位置与笔尖位置在空间中的几何关系,恢复笔尖的运动轨迹。本文对靠近笔尖处的标签移动轨迹进行定位,提出了双曲线差分全息图算法,有效削弱手臂对RF信号的动态干扰,从而提高系统的鲁棒性。对笔尖处标签的追踪效果进行实验评估,实验结果表明:在消除初始偏移量后,系统的平均轨迹误差为2.75cm。在获得笔尖处标签在每一个时间点的坐标之后,对靠近笔尾处的标签运动轨迹进行追踪,本文提出了空间中曲面全息图定位算法,获得笔尾处标签在3D空间中的方向坐标。对笔尾处标签在3D方向上的误差进行实验评估,实验结果表明:在消除初始偏移量后,系统的仰角和方向角之间的平均误差分别为6.4°和7.8°。在获得笔尖处标签的位置信息和笔尾处标签的方向信息后,本文设计了笔尖坐标还原算法,将标签的位置和方向与笔尖在书写平面上的位置相结合,获得精确的笔尖书写轨迹。通过一系列实验对该系统的性能进行了评估,并与经典的基于RFID的手写轨迹追踪系统进行比较。实验结果表明:在消除初始偏移量后,系统的平均轨迹误差为2.8cm,字符平均识别准确率为93.6%,均优于所对比的基于RFID的手写轨迹追踪系统。

关键词： 巨型水电机组励磁功率柜   RFID测温标签   传导电磁干扰   辐射电磁干扰   受扰分析  

摘要： 随着2020年我国双碳目标的提出,以清洁能源为主的新一代电力系统的单机容量及装机规模正不断上升,由此使得电力设备的状态监测成为重中之重。其中,电力设备的运行温度及其变化是反映其运行状态是否正常的重要标志。基于射频识别(Radio Frequency Identification,RFID)的温度传感技术是目前电力设备在线测温方式中最为灵活、便利和有效的方法之一,也是当前学术研究和工程应用的热点。本文以乌东德水电站7#机组励磁功率柜内晶闸管温度监测为例,开展了以下研究工作: 首先,本文采用平面矩形贴片方案,以平面微带线作为天线馈电,用铜作为天线辐射的导体材料,选择1.6mm厚的双面覆铜的FR4板作为介质基板,设计了一款基于短路短截线结构的RFID抗金属测温标签天线;在乌东德水电站7#机组的励磁功率柜中展开了RFID抗金属测温标签的现场应用测试,功率柜在小功率运行期间,测温标签工作正常,在大功率运行期间,测温标签出现数据丢失现象,由此初步判断RFID测温标签在励磁功率柜内受到了严重的电磁干扰。 其次,本文详细分析了励磁功率柜的电气结构及其主电路,并通过7#机组发电机参数对主电路进行MATLAB/Simulink仿真,得到了晶闸管的电压和电流特性曲线;针对励磁功率柜在大功率运行工况下,RFID测温标签因受电磁干扰导致失效的问题,在三维电磁场仿真软件(Computer Simulation Technology Studio Suite,CST Studio Suite)中构建了励磁功率柜的电磁仿真模型,并以晶闸管的典型电流工况为依据对电磁仿真模型进行了激励源设置,采用时域有限差分法,进行了励磁功率柜晶闸管组件的电磁特性仿真分析,得到了功率柜在大功率运行工况下其内部散热器的电磁场分布特征。 最后,本文通过理论计算得到RFID测温标签-散热器寄生电容,通过仿真计算得到散热器与进线排寄生电容;根据所得寄生参数建立了励磁功率柜主电路电磁干扰仿真模型,分析了励磁功率柜主电路产生的传导干扰和辐射干扰的路径,证实励磁功率柜在大功率运行期间内部产生了电磁干扰;结合RFID测温标签天线模型和励磁功率柜主电路的电磁干扰仿真模型,建立了RFID测温标签的电磁受扰仿真模型,分析了其受扰时天线性能参数的变化特征,明确了励磁功率柜在大功率运行期间RFID测温标签失效机理。 本文经过理论分析和仿真验证,发现励磁功率柜内存在传导电磁干扰和辐射电磁干扰,其中传导电磁干扰的影响比辐射电磁干扰更为显著。尤其是传导电磁干扰可对励磁功率柜内的RFID测温标签造成严重的影响,使其工作性能明显下降;而辐射电磁干扰对RFID测温标签的影响则相对较小。下一步本文将开展电磁干扰的实际测试工作,收集电磁干扰实测数据,对励磁功率柜的电磁干扰仿真模型进行修正,并针对性地研究大功率电力电子设备内RFID测温标签的抗干扰设计和方法。

关键词： Radiofrequency identification   Harmonic analysis   Radar   Radar tracking   Passive RFID tags   Transponders   Insects   Radio frequency identification (RFID)   passive RFID   harmonic radar   harmonic transponder   nonlinear backscatter  

摘要： Radio frequency identification (RFID) has gained significant attention because it provides a highly versatile platform for identifying, tracking, and monitoring objects. An emerging trend in this technology is the use of nonlinear RFID, such as passive harmonic tags, which have been demonstrated to be effective against clutters, echoes, crosstalk, and other electromagnetic interferences. This article presents a comprehensive review of recent advances and applications of passive harmonic RFIDs and integrated systems. A passive harmonic RFID exploits the frequency orthogonality of the transmitted (fundamental tone) and received (harmonics) radio-frequency (RF) signals to enable robust interrogation in noisy and cluttered environments, not possible with traditional passive linear RFIDs. This review article evaluates passive harmonic RFID systems in comparison to traditional systems and highlights their pros and cons. Several state-of-the-art chipless and chip-based harmonic RFIDs are presented, and their novel applications in identification, tracking, sensing, and biotelemetry are discussed. The review summarizes the key successes and challenges of passive harmonic RFID systems and provides insights into their future development, implementation, and optimization.

关键词： 医疗废物处置   医废监控   时效预警   费用结算   请款对接   RFID   DevExpress Dashboard   医废风险模型  

摘要： 随着医院科室和规模的不断增加,医院医疗废物种类和产生量也随着增加,医院医疗废物监控管理面临严峻的考验。在现阶段医院医疗废物监控管理过程中出现了以下管理难点:医废处置过程中出现非必要的人为接触;医废处置异常情况无法完整记录和跟踪;医废处置费用类别繁多导致业务不明确。因此,医院急需开发一套满足现阶段需求的医疗废物监控管理系统。医院医疗废物监控管理系统开发基于RFID、Uni-app开发组件、VS Code开发工具、Redis技术、SQL Server数据库、TaskFactory任务组件,DevExpress Dashboard等技术。在系统背景调研阶段,对国内外研究现状进行了分析,得出了系统建设方向和意义。系统的需求调研采用软件研发的一般原则分析业务、功能、非功能,构建完整的需求。在系统设计部分,结合类图、顺序图对功能详细设计细节进行说明,结合数据库E-R图和数据表结构对系统数据库设计思路进行介绍,结合接口规范对系统接口设计细节进行说明。在系统实现环节,结合系统功能界面和功能核心代码,对系统功能实现思路进行说明。针对医废风险分析问题,采用决策树算法构建预测模型,以存放时间、存放等级、混合状态、运输情况等特征训练后形成决策判定树,有效地提高医废监测的效率。在系统测试过程中,对系统测试原则和测试环境进行介绍,对系统功能测试和性能测试细节进行展示,对系统测试结论进行分析。医院医疗废物监控管理系统包含医废处置管理、医废监控、医废设备管理、医废处置费用结算管理、系统管理五大功能模块。借助系统的应用,医院有效实现了医疗废物监控管理环节的规范化和信息化,实现了医疗废物管理风险的主动预警,降低了医疗废物管理风险。通过和医院请款系统对接,实现了医废处置资费、费用计算、账单生成、审核、请款全流程的管理,提高了医废处置费用结算的透明度。本论文包含图36幅,表23个,参考文献46篇