标签运动状态下的RFID系统反碰撞算法

针对现实应用中标签经常处于运动状态的情况,对传送带模型下的无线射频识别(RFID)系统进行了分析,并使用Matlab做了相应的仿真实验。结果证明,当标签密度D与传送带速度V保持不变时,识别率P在帧长度N与作用范围内未识别标签数n相等时最高。当时隙持续时间一定时,识别率P只与V和D有关,而与作用区域内传送带长度L无关。同时针对该模型,对现有的标签估算方法进行了修正,在此基础上提出了一种新的估算方法,该方法的准确度在标签数目较大时有着明显的提高。     

基于内容的网页特征提取

文章主要研究基于内容的中文网页的特征提取技术,具体介绍了分词词典的建造方法,网页正文、标记信息和超链信息的特征提取。通过对旅游类网页的实验结果显示,文中的方法和应用效果良好。     

Environmental effects on the coevolution of pursuit and evasion strategies

The game of tag is frequently used in the study of pursuit and evasion strategies that are discovered through competitive coevolution. The aim of coevolution is to create an arms race where opposing populations cyclically evolve in incremental improvements, driving the system towards better strategies. A coevolutionary simulation of the game of tag involving two populations of agents; pursuers and evaders, is developed to investigate the effects of a boundary and two obstacles. The evolution of strategies through Chemical Genetic Programming optimizes the mapping of genotypic strings to phenotypic trees. Four experiments were conducted, distinguished by speed differentials and environmental conditions. Designing experiments to evaluate the efficacy of emergent strategies often reveal necessary steps needed for coevolutionary progress. The experiments that excluded obstacles and boundaries provided design pointers to ensure coevolutionary progress as well as a deeper understanding of strategies that emerged when obstacles and boundaries were added. In the latter, we found that an awareness of the environment and the pursuer was not critical in an evader’s strategy to survive, instead heading to the edge of the boundary or behind an obstacle in a bid to ‘throw-off or hide from the pursuer’ or simply turn in circles was often sufficient, thereby revealing possible suboptimal strategies that were environment specific. We also observed that a condition for coevolutionary progress was that the problem complexity must be surmountable by at least one population; that is, some pursuer must be able to tag an opponent. Due to the use of amino-acid building blocks in our Chemical Genetic Program, our simulations were able to achieve significant complexity in a short period of time.

Prototypical implementation of location-aware services based on a middleware architecture for super-distributed RFID tag infrastructures

We provide evidence of the feasibility and effectiveness of a middleware architecture for mobile devices (MoDs), which employs dense distributions of small computerized entities for providing fault-tolerant location-aware services. We do so by describing exemplary implementations based on radio frequency identification as an enabling technology. Firstly, we present prototypical implementations of the hardware abstraction layer and of selected core middleware services. The latter enable a MoD to store and retrieve data and position information in physical places in a fault-tolerant manner, and to identify places based on a location abstraction which is robust against failure of individual tags. Secondly, we investigate the feasibility of some higher-level services and applications by developing and evaluating prototypical systems for tracing and tracking, self-positioning, and collaborative map-making.

传感射频识别系统中多逻辑传感器研究

射频识别（radio frequency identification,RFID）与传感器技术的融合是当前物联网技术发展的必然趋势。在传感器与射频识别融合的传感射频识别系统中,现实应用需求的多样性决定了传感标签中一个物理传感器要实现多个逻辑传感器功能。基于传感射频识别系统,主要研究了传感标签中逻辑传感器的功能定义,逻辑传感器采样参数的配置,同时也研究了逻辑传感器数据在传感标签中的存储模式、逻辑传感器的运行机制和逻辑传感器功能的算法实现。采用该多逻辑传感器研究方案,开发了一套传感射频识别系统,用于监控集装箱内物品温度、湿度、振动和防盗,取得了良好的效果。     

基于EPC Gen2协议的UHF RFID有源电子标签设计

提出了一种基于EPC Gen2协议的UHF RFID(Radio Frequency Identification)有源电子标签设计方法。标签硬件电路分为三个部分——反射电路、接收电路和基带控制电路。通过理论分析提出一种低误码率的反射电路设计方案,接收电路采用双通道正交解调方案,采用FPGA芯片EP1C3T100C6完成基带控制电路设计。利用读写器对标签进行测试,示波器、频谱仪和上位机程序所得结果均表明标签工作正常。     

RFID动态标签估计防碰撞算法

针对无线射频识别(RFID)过程中标签之间的碰撞问题,提出一种新的RFID防碰撞算法。利用二进制碰撞算法动态地估计一部分将要被识别的标签数,通过标签生成的随机数对其进行分组,并识别该部分标签。实验结果表明,该算法能有效减少冲突发生的概率,识别标签的效率为42.5%~42.8%。     

矿井组合导航系统算法研究

针对矿井环境下人员定位精度差的问题,提出一种基于射频位置修正技术的新型矿井组合导航系统。将捷联式惯性导航系统 (SINS)与矿井射频定位进行互补融合,将射频标签存储的实际位置和SINS解算位置的差值作为量测量,利用扩展Kalman滤波器估计并补偿SINS存在的陀螺漂移和加速度计零偏。仿真结果表明,在复杂度相近的情况下,该系统在30 min内的综合定位精度比SINS提高近 4倍。     

基于RFID技术的课堂考勤系统设计

本文研究和设计了一种基于射频识别（RFID）技术的课堂考勤系统。此系统是利用RFID技术,实现对到课堂上课人员的简单快速地自动点到和离开课堂的记录,保存相关的数据信息供教职人员检阅,从而免去平时点名占用的课堂时间。这里简单介绍了课堂考勤系统的基本功能和组成,然后对系统各重要组成部分进行了详细的分析。     

RFID系统中改进的混合查询树防碰撞算法

针对无线射频识别(RFID)技术系统中的标签碰撞问题,采用混合查询树与多叉树结合的方法,提出一种改进的混合查询树防碰撞算法。在QT算法的基础上,通过标签序列生成器判断标签碰撞信息,结合八叉树询问机制,避免空闲周期和延迟时隙产生,减少碰撞以及标签冲突和系统开销。实验结果证明,该算法优于QT、HQT算法,可减少查询次数和系统通信量,改进的混合查询树算法的识别效率较HQT算法提高46.1%。