导波雷达物位计在储气库应用研究

液位检测是储气库采气流程中的关键参数,关系到整套采气装置联锁控制稳定和安全平稳生产.针对导波雷达物位计在储气库分离器设备液位检测应用中发生液位检测失准的情况,通过对导波雷达物位计测量原理分析和研究,查找存在问题的原因,提出了解决问题的方法,取得了良好的效果,为储气库安全生产奠定良好的基础.     

磁致伸缩液位仪的应用研究

介绍了磁致伸缩液位仪的工作原理、技术特征、应用范围,分析了磁致伸缩原理在液位测量中的典型应用。从油品计量与监控、过程监控、LPG罐区监测等方面,讨论了磁致伸缩液位仪在实际测量中所具有的优越特性,成为液位测量中的理想选择。     

核电站高位水箱液位测量改造

液位测量是核电站自动控制系统中的重要组成部分。脉冲式导波雷达液位变送器基于电磁波的时域反射(TDR)原理,具有受环境影响小、测量精度高等诸多优点。电站高位水箱改造项目是采用导波雷达液位变送器及横河控制组合应用。阐述了导波雷达液位变送器的工作原理,现场设备安装参数设置,以及在调试过程中控制器参数设置。     

雷达液位仪多端口通信模块设计

雷达液位仪是一种非接触式的高精度液位测量仪表。针对现有雷达液位仪的通信方式比较单一的现状，设计了一种多端口的通信模块，使得雷达液位仪同时具有CAN总线、工业以太网等接口功能。给出了硬软件的设计方案，为组建基于CAN总线和工业以太网的液位测量网络系统打下了基础。实验表明，该通信模块具有结构简单，工作稳定可靠、通信速率高等特点。     

基于微波与CAN总线技术的储油罐液位测量系统设计

给出了基于微波与CAN总线技术的储油罐液位测量系统的组成及方案设计,该系统主要由监控计算机、雷达液位仪及基于CAN总线的通信单元组成,采用CAN适配卡实现通信,并用高性能的16位单片机控制雷达液位仪.重点给出系统总体设计及原理、通信系统设计、系统软件设计.     

原油储罐雷达液位仪应用

原油储罐是油田存储好油、坏油的重要设备，储罐液位是原油集输工艺的重要参数之一。采用人工检尺等接触方法测量液位存在种种弊端，非接触雷达液位仪可以解决液位检测中误差大、不安全等问题。     

导波雷达液位计在方家山核电站的应用

液位测量是核电站自动控制系统中重要组成部分。导波雷达液位计基于电磁波的时域反射(TDR)原理,具有受环境影响小、测量精度高等诸多优点。方家山项目是导波雷达液位计第一次在二代改进型核电站核岛厂房进行应用。通过研究,报告了导波雷达液位计在方家山项目中的选型与应用,阐述了导波雷达液位计的工作原理、性能特点、使用注意问题以及在ASG系统液位测量方面的应用。     

多参数油水界面仪在油水界面测量中的应用

导波雷达液位计作为化学工业中常见的液(界)位测量仪表,在测量油水界面时有着自身的优势。但传统的导波雷达液位计由于其自身的局限性在实际应用中,尤其是测量含乳化层的油水界面时,经常会出现界面信号被液位信号吞噬的弊病。本文介绍的多参数油水界面仪是对传统导波雷达液位计的升级,通过测量原理的分析及实际应用案例验证了多参数油水界面仪在测量含乳化层的油水界面应用中的优势,为自动化领域的界面测量提供一种有效可行的解决方案。     

HART协议磁致伸缩液位仪的研制和应用

分析磁致伸缩液位仪的结构和工作原理，介绍仪表工作电路和HART协议设计，讨论磁致伸缩液位仪的关键技术和优缺点，并介绍在工业现场的应用情况。     

油罐计量技术的革命-超高精度磁致伸缩液位仪

介绍了磁致伸缩材料,详细描述了磁致伸缩液位仪的工作原理、技术特征及在液位测量中的应用和发展前景.     

基于压缩传感理论的随机等效采样信号的重构

随机等效采样技术通过对周期信号进行多次随机时间间隔取样,以时间间隔为序排列采样数据,形成具有较高等效采样率的波形。然而,由于时间间隔的非均匀性,很难采集到足够的有效信号重构原始波形。为了克服这种信息不足引起的重构误差,提出了一种基于压缩传感理论的随机等效采样信号重构方法,构造了随机等效采样测量矩阵。该方法能够对周期信号以低于信号奈奎斯特频率的采样率进行随机采样,通过最优化问题从有限的采样值中重构原始信号。最后通过实验对该方法的可行性进行了验证。     

Measurement of active power by time domain digital signal processing

This paper compares DSP time domain algorithms of one-phase active power measurement by non-coherent sampling that are superior to some frequency domain algorithms in active power estimation of non-sinusoidal signals. The measurement bias, uncertainty and sampling time necessary for the required accuracy are compared for various data windows with the use of simulations and measurements. Both monofrequency and multifrequency signals are dealt with. Analytical formulas are presented for the active power bias for rectangular and general cosine windows and for standard uncertainty of active power measurement. A simple method is described for correction of the multiplexing delay in power measurement using multiplexing DAQ boards. The information from this paper can also be used for measuring energy consumption and three-phase power.     

Subsample interpolation bias error in time of flight estimation by direct correlation in digital domain

This work presents an investigation of the bias error introduced in time of flight estimation realized by subsample interpolation in digital domain. The time of flight estimation is accomplished based on the evaluation of the peak position of the cross correlation function. In order to cope with the discrete nature of the cross-correlation function, subsample estimation exploits three time domain interpolation techniques: parabolic, cosine, Gaussian and frequency domain interpolation using phase angle. An empirical equation relating the maximum value of the bias error to sampling frequency and signal parameters (center frequency and envelope bandwidth) has been derived. It is found that the maximum value of the bias error is in inverse cubic relation to sampling frequency and in quadratic relation envelope bandwidth for cosine interpolation. The maximum value of the bias error is in inverse cubic relation to sampling frequency and in quadratic relation to center frequency and envelope bandwidth for parabolic interpolation. The coefficients related to the approximation technique are given. Results can be applied for bias errors estimation or correction when fast subsample interpolation is used and application of phase domain interpolation is unacceptable due to processing speed limitations. The equations for minimum required sampling frequency are derived by balancing the interpolation error against Cramer–Rao lower bound.     

Adaptive sampling interval cause-selecting control charts

This article considers the statistical adaptive process control for two dependent process steps. We construct an adaptive sampling interval Z _X control chart to monitor the quality variable produced by the first process step, and use the adaptive sampling interval Z _e control chart to monitor the specific quality variable produced by the second process step. By using the proposed adaptive sampling interval control charts, we can quickly detect and distinguish which process step is out of control. The performance of the proposed adaptive sampling interval control charts is measured by the adjusted average time to signal (AATS), which was derived by a Markov chain approach, for an out-of-control process. An empirical automobile braking system example shows the application and the performance of the proposed adaptive sampling control charts in detecting shifts in process means. Some numerical results obtained demonstrated that the performance of the proposed adaptive sampling cause-selecting control charts outperforms the fixed sampling interval cause-selecting control charts.     

圆柱面形状误差评定的理论与方法

围绕着精确评定圆柱面形状误差的问题，较为全面系统地提出了一套理论和方法。它包括：用于圆柱面形状误差测量的采样原理；精确评定其形状误差的统一数学模型；误差评定求解的优化理论和方法；求解过程中的删点方法以及利用模拟基准件对测量仪器或测量结果验证的方法等，并按照上述主要理论，研制了微机控制的圆度检测系统。经大量实验验证，本理论正确、方法可行。测量系统的精度达到０．０４μｍ。     

分离式数字记录装置的双级时隔记录算法

分离式数字记录装置是一种与外界无连结、也不与外界进行任何形式的无线通讯的记录装置。它主要用于对缓慢变化的被测量（如西部某地恶劣环境温度）进行长期自动的数据采集后，再取回用微机对其所记数据进行分析。其主要设计要求是简单、便宜、可靠、和存储器一次可记录时间（从装置存储器第一个单元记录有效数据算起，到最后一个单元被占。）长。在文献[1]中提出并讨论了时隔门限记录法，通过对被测量取一适当的门限值并采用一种特别的相对时隔记录方法，延长了存储器的可用时间。提出并详细描述了一个称为双级时隔记录法的新算法及其恢复算法，利用此方法，既可以获得较长的记录时间，又可以在一定程度上捕获得被测量的一结短时变化。在某些场合这样做是必要的。     

航空发动机复杂磨损趋势的神经网络多变量预测模型

针对非等间隔的受加油因素影响的光谱油样分析数据的建模预测问题,建立了BP神经网络的多变量预测模型,充分考虑了油样分析数据的非等间隔性及受加油因素影响的特点,同时,用遗传算法对网络参数进行了优化。最后,利用两组实际的航空发动机油样光谱分析数据对模型进行了验证。结果表明,所提出的神经网络多变量预测模型能有效解决实际的受多因素影响的油样分析数据建模问题,具有较强的工程实用价值和通用性。     

便携式振动信号分析系统的设计与实现

本文主要描述了一种基于USB 2.0接口的振动信号分析系统的设计与实现。信号调理部分主要运用了锁相环技术实现对振动信号的整周期采样和自适应抗混叠滤波;然后采用CYPRESS公司的USB2.0芯片CY7C68013A实现采集硬件与PC机的连接;接着利用VC 调用Measurement Studio强大的信号分析函数,使用CWGraph图形控件,对振动数据进行同步分析和显示,此方式改进了硬件设计的工作量大,开发周期长,系统可扩展性能较差的缺点。     

An enhancement of DSI X̄ control charts using a fuzzy-genetic approach

A traditional control chart used to monitor a process draws the process data at a fixed sampling rate, while a variable sampling interval (VSI) control chart varies the sampling rate as a function of on-line process data. In such a sampling policy, a higher sampling rate is adopted when there is suspicion of a change in a process. Therefore, it is able to detect the process change faster than traditional control chart, and thus has been much accepted for use. Nevertheless, the binary suspicious grade used in VSI policy to specify the sampling rate is not detailed enough to explain the acquired information from process data. As a result, this paper aims to refine the suspicious grade and sampling interval lengths to increase the detection ability of VSI charts. This study first establishes a composition function on two sides of the control chart by introducing the concept of fuzzily suspicious grade to specify the sampling rate. Then, genetic algorithms (GAs) is used to adjust the values of the parameters in this composition function to enhance the dual-sampling-interval (DSI) charts-one type of the VSI charts in common use-in terms of average time to signal (ATS) for process mean shift. In addition, some statistical properties of the enhanced DSI charts as well as performance comparison to traditional DSI charts are provided and analysed.     

Mechanical filtration of surface profiles

This paper presents the analysis of factors affecting the small wavelength content of profile after measurement by stylus profilometer. Three following factors are considered: the shape and size of stylus tip sampling interval, and short-wavelength cut-off. The effect of mechanical filtration of replica measurement is considered. The influence of skid is also analysed. The real and computer generated random profiles of normal and asymmetrical shapes of the ordinate distribution are the objects of investigation. 2D profiles are analysed, but the effects of tip radius size as well as the skid effect were analysed in three-dimensional surface.