Design and Performance Analysis of Emulator for Standard Conformance Test of Active RFID

An active radio frequency identification (RFID) system has the advantages of a long identification distance and a good identification rate, overcoming passive RFID drawbacks. Therefore, interest in the development of active RFID systems has been gradually increasing in areas of harbor logistics and national defense. However, some identification failures between active RFID systems developed under the same standards have been reported, presumably due to a lack of development of accurate evaluation methods and test equipment. We present a realization of the hardware and software of an emulator to evaluate the standard conformance of an active RFID system in a fully anechoic chamber. The performance levels of the designed emulator are analyzed using Matlab/Simulink simulations, and the applicability of the emulator is verified by evaluating the standard conformance of a real active RFID tag. Finally, we propose a new evaluation method by incorporating a self‐running test mode environment into the RFID tags to reduce testing time and increase testing accuracy. The application of the suggested method to actual tags improves measurement uncertainty by 0.56 dB over that obtained using existing methods.     

Value‐centric framework and pareto optimality for design and acquisition of communication satellites

Investments in space systems are substantial, indivisible, and irreversible, characteristics of high‐risk investments. Traditional approaches to system design, acquisition, and risk mitigation are derived from a cost‐centric mindset, and as such they incorporate little information about the value of the spacecraft to its stakeholders. These traditional approaches are appropriate in stable environments. However, the current technical and economic conditions are distinctly uncertain and rapidly changing. Consequently, these traditional approaches have to be revisited and adapted to the current context. We propose that in uncertain environments, decision‐making with respect to design and acquisition choices should be value‐based. We develop a value‐centric framework, analytical tools, and an illustrative numerical example for communication satellites. Our two proposed metrics for decision‐making are the system's expected value and value uncertainty. Expected value is calculated as the expected NPV of the satellite. The cash inflow is calculated as a function of the satellite loading, its transponder pricing, and market demand. The cash outflows are the various costs for owning and operating the satellite. Value uncertainty emerges due to uncertainties in the various cash flow streams, in particular because of market conditions. We propagate market uncertainty through Monte Carlo simulation, and translate it into value uncertainty for the satellite. The end result is a portfolio of Pareto‐optimal satellite design alternatives. By using value and value uncertainty as decision metrics in the down‐selection process, decision‐makers draw on more information about the system in its environment, and in making value‐based design and acquisition choices, they ultimately make more informed and better choices. Copyright © 2009 John Wiley & Sons, Ltd.     

温度传感器自动检测系统误差分析

温度传感器自动检测系统主要通过被测件与标准器的实时比对,实现对传感器的精确测量,而系统的误差分析则是保证测试精度的关键.介绍了温度传感器自动检测系统的组成及测试方法,并且通过对一只温度传感器的实测,详细分析了影响该系统测试精度的几种误差来源,同时对各个误差的不确定度进行r分析和评定,最后给出了整个系统的总不确定度.     

自动气象站检定结果不确定度的评定与表示

测量不确度是测量系统最重要的特性指标,它表征了测量结果的分散性,是对测量结果质量的定量表征。本文根据中华人民共国国家计量技术规范JJF1059—1999《测量不确定度评定与表示》中所述方法,通过对自动气象站各要素检定结果的各分量的分析,合理选择测量结果不确度的评定方法,对各要素在测量结果的分散性进行较为科学的评定,为自动气象站观测数据的准确性及可靠性提供依据。     

用逐步扩展法处理输电网规划中不确定性因素

输电网规划中不可避免地会涉及大量规划人员控制或预料之外的不确定性因素,合理的规划方法是将处理不确定性因素的方法与最优方法有机结合。针对电力市场环境下输电网规划面临大量不确定因素的影响,结合逐步扩展法,提出了采用半不变量法处理输电网规划中的不确定性因素。改进的"19节点系统"验证了所提方法的可行性。计算结果表明:所提方法的特点是计算速度快、且不存在不收敛问题。     

电站锅炉排烟热损失的不确定度分析

介绍了电站锅炉热效率试验中排烟热损失的不确定度分析,针对试验过程中的测量数据,通过计算实例说明排烟温度、排烟氧量和送风温度的不确定度对排烟热损失不确定度的影响较大。     

具有不确定参数的车辆跟随滑模控制

假定车辆质量及作用在车辆上的空气阻力、地面对轮胎的摩擦力等参数随时间变化但有界,研究自动化公路系统车辆纵向跟随控制。根据车辆不确定参数的有界性和滑模控制策略,采用饱和函数法,设计了车辆跟随系统的纵向变结构控制规律;基于李雅普诺夫稳定性方法,对控制系统的稳定性进行分析,并确定系统收敛的充分条件。仿真结果表明:采用所设计的控制方法,在达到满意跟踪性能的同时,还能有效抑制控制颤振,对参数不确定性具有鲁棒性。     

一类不确定时滞系统的关联稳定和协调控制(英文)

针对有两个独立子系统的线性不确定时滞系统,研究其关联稳定和协调控制问题.采用线性矩阵不等式和双线性矩阵不等式方法,针对凸多面体不确定性,给出了两个独立的不确定时滞子系统关联稳定和协调控制的充分条件,并进一步将协调控制器的设计问题转化为求解相应的最优化问题,设计了求解优化问题的最优迭代算法.最后,通过一个数值算例验证了所设计的协调控制器能镇定不稳定的子系统,说明了所得结果的有效性.     

基于量值特性的ATS动态测量不确定度评定

针对ATS测量不确定度难以全面评价的难题,用基于量值特性的动态测量不确定度评定方法对ATS测量不确定度进行评定。分析了ATS和动态测量的概念及关系,阐述了基于量值特性的动态测量不确定度评定方法,并以自动测试系统的数字多用表直流电压10V量程为例,分析了应用该方法进行动态测量不确定度评定的全过程。结果表明：应用该方法进行不确定度评定具有方法简单、不确定度来源分析全面、评定结果准确等优点。     

面向运行规划可靠性的综合聚类负荷模型

针对目前运行规划可靠性评估中负荷模型的不足,提出了一种综合聚类负荷模型,该模型能综合考虑负荷节点的特征量信息,分类精度显著提高.对研究时段内的多个负荷水平进行综合聚类的基础上采用多维正态分布抽样技术,计及节点负荷相关性和负荷预测标准差,确定评估期间的节点负荷值.在负荷分类基础上结合累积概率负荷模型,推导了停电频率指标的计算公式,解决了非序贯仿真中考虑负荷转移的频率计算问题.通过算例,分析了负荷分类、负荷预测不确定性、节点负荷相关性和负荷转移频率对可靠性指标的影响,验证了模型的正确性和有效性.