A nonlinearity error calibration technique for pipelined ADCs

This paper presents a digital background calibration technique that measures and cancels offset, linear and nonlinear errors in each stage of a pipelined analog to digital converter (ADC) using a single algorithm. A simple two-step subranging ADC architecture is used as an extra ADC in order to extract the data points of the stage-under-calibration and perform correction process without imposing any changes on the main ADC architecture which is the main trend of the current work. Contrary to the conventional calibration methods that use high resolution reference ADCs, averaging and chopping concepts are used in this work to allow the resolution of the extra ADC to be lower than that of the main ADC.     

IMT—Advanced协作多点传输技术——信道互异性校准

文章以协作多点传输技术为背景,基于信道互异性模型,介绍了3类较为典型的校准算法：基于硬件检测的自校准方法、基于天线自检测反馈的自校准方法、基于校准天线检测反馈的互校准方法。以此为基础,文章分析和研究了各校准算法的特性,评估和仿真了各校准算法协作多点传输技术在各类联合预编码算法下的系统性能,同时预测了校准算法未来的研究进程及可能面临的挑战。     

713C天气雷达的回波强度定标

为了抵消天气雷达的参数变化所引起的雷达回波强度的误差 ,根据天气雷达回波强度定标的基本原理 ,结合我们多年来在天气雷达的参数测量、系统调整及回波强度定标中累积的经验 ,将详细地论述 713C天气雷达回波强度定标的内在过程 :给出了回波强度定标的软件流程、介绍了雷达定标前的准备工作及定标过程、说明了 713C天气雷达回波强度定标文件的形成方法、又提出了几种对天气雷达定标结果的验证方法。这样才能使得定标后天气雷达残存的回波强度误差在整个接收系统对数动态线性范围内控制在 2dB以内 ,保证天气雷达定量探测降水回波的准确性     

Recognizing jump patterns with physics-based validation in human moving trajectory

This paper presents an approach to recognize jump patterns in human moving trajectory, differentiating jump tracks from planar moving tracks. Since human moving trajectory is one of the most informative representations for content understanding and event detection, trajectory-based video analysis has been gaining popularity. However, a jump action typically leads to violent change in human moving trajectory, since the person suddenly leaves the original plane on which he/she has been moving. The abnormal tracks of the trajectory would influence the performance of trajectory-based video analysis. Hence, differentiating jump tracks from planar moving tracks is of vital importance, not to mention that jump actions typically imply significant events, especially in sports games. In this paper, volleyball videos are used as case study to demonstrate the effectiveness of our proposed jump pattern recognition approach. We derive player trajectory by head tracking, analyze the movement of each player, and recognize potential jump tracks in player trajectories based on two important characteristics: (1) jumps cause pulse-like tracks in the trajectory and (2) the extensions of such tracks go through the vanishing point of vertical lines in the scenes. Finally, the jump positions/heights are estimated, in addition to the planar moving trajectory of each player on the court ground. The experiments show that satisfactory results can be obtained with the proposed recognition scheme.     

建设工程检测实验室测量设备管理问题的探讨

全文以测量设备的管理为主要核心,围绕测量设备管理、如何选择检定与校准、量值溯源的总体要求、服务机构选择、测量设备的计量确认等几个方面阐述了测量设备管理在工程建设实验室管理中的重要性。     

基于改进粒子群优化算法的摄像机标定

本文在充分研究多种摄像机标定方法和粒子群优化算法（PSO）的基础上,针对传统PSO算法存在早熟和局部收敛的问题,提出了一种改进的新型粒子群优化算法在摄像机标定中的应用。该算法在基本PSO惯性权重部分加入了收缩因子,很好的改善了算法的收敛性;为了进一步提高优化的速度和可靠性,引入了多适应值函数策略。最后在OpenCV上实现了基于该改进方法的摄相机标定。实验结果表明：该摄像机标定方法有效提高了原有张正友平面标定法的标定精度,结果稳定可靠,具有一定的工程应用价值。     

基于温度影响的BOTDR监测数据实验研究

文章以布里渊散射光时域反射测量计(BOTDR)工作原理为基础,以监测工作中常用的φ0.9SM单芯紧套光纤在恒温实验室内的实验数据为依据,采用统计分析和线性回归方法,对其监测数据的环境温度影响进行了校正分析,有效剔除了因环境温度影响而造成的BOTDR监测数据假应变,取得了良好效果.     

轴承振动测量仪校准方法研究

轴承振动测量仪是用来测量轴承振动加速度的重要计量仪器,种类繁多,应用广泛,但缺乏有效的校准检定方法。文中结合作者多年来从事振动方向校准检定的实践经验和深入的理论分析,提出了两种切实可行的校准方法,对该类仪器的校准有积极的指导意义。     

宽带DBF系统多通道校正及性能分析

针对数字波束形成(DBF)技术在宽带扩频通信系统中的应用,提出了一种基于复数傅里叶变换(CFFT)的宽带多通道校正方法。采用宽带线性扫频信号作为通道幅相误差校正的测试信号,在采集实际接收机数据的基础上,分析了信噪比、频谱泄漏以及由通道校正滤波器引起的群时延对校正精度的影响。通过修正复系数FIR滤波器(CFIR)的频域响应特性可以有效消除群时延的影响。依据宽带测试信号的时域和频域特性,选择适当的FFT点数,解决了测试信号频谱泄漏引起的校正精度低的问题。理论分析与实测结果都表明了该方法的有效性。利用实际数据仿真了天线阵列波束方向图,结果显示校正后的波束图十分接近理想情况下的波束图,两者峰值增益相差仅仅0.1dB,指向误差近似为0。     

扫描电子显微镜在植物中的应用研究进展

扫描电子显微镜(SEM)作为一种行之有效的科研分析工具,可对多种植物材料的表面形貌进行观察研究,具有较广的应用范围.本文论述了扫描电子显微镜样品的制备以及在植物花器官、种子表皮、种子形态、叶片表皮、内含物、病原体以及在植物细胞水平的研究进展,并对今后扫描电子显微镜的应用前景进行了展望,以期为利用SEM从事植物研究的科研...