空气浮力修正对质量测量的影响分析

在进行质量量值传递时,空气浮力修正成为重要的影响量。本文通过对空气中质量测量的基本原理分析和折算质量计算公式推导,推导出空气浮力修正因子。文中进行了空气浮力因子的数值模拟,通过数值模拟曲线分析出空气浮力修正因子的影响,并在曲线图上便捷的查出空气浮力修正因子,直接应用于砝码折算质量的计算。     

质量基准量值传递过程中空气浮力影响的研究

CIPM-1981,CIPM-81/91和CIPM-2007公式在质量测量过程中,计算空气浮力修正影响量存在着明显的差异。为了分析3个公式对质量基准量值传递过程中空气浮力的影响,在不同条件下对使用3个公式计算空气浮力修正进行比较。结果表明:基于国家千克基准60号和国家千克副基准121号的体积参数,在不同环境条件下采用CIPM-1981、CIPM-81/91和CIPM-2007公式进行空气浮力修正过程中,质量差值最大可达42μg。     

关于F1等级砝码空气浮力修正的不确定度评定

对于准确度等级高的砝码在进行折算质量的不确定度评定时,要考虑空气浮力修正,如果空气浮力小于被测砝码最大允许误差的九分之一时,可不进行空气浮力修正,而将其放人空气浮力不确定度进行计算。     

基于车载诊断系统的汽车虚拟仪表

针对传统汽车仪表的局限性,利用OBD-Ⅱ系统开发了一种可用于汽车故障诊断的汽车虚拟仪表.仪表系统用扫描仪通过OBD诊断座与OBD-Ⅱ系统以串行方式通信,读取该系统存储在执行控制单元中的数据,对数据解释后获得车辆行驶数据和故障码.虚拟仪表由ActiveX仪表控件拼搭而成.实验表明,该虚拟仪表可对车辆进行实时监控、故障显示和行车参数记忆存储,具有较好的扩展性和通用性.     

基于图像识别的数字多用表自动校准系统开发

手持式数字多用型号规格多种多样,需校准的数据点非常多,人工校准过程耗时费力,且容易产生错误.本文提出了基于图像识别技术的数字多用表自动校准系统(以下简称系统)方案,系统根据被校准数字多用表的量程及最大允许误差指标等参数生成校准记录模版,对于每个校准点采用SCPI语句控制标准源的输出标准值,通过图像识别的方式读取校准结果,并进行误差计算和符合性判定等处理分析,最终导出Excel版原始记录及校准证书内页,校准效率及工作质量显著提升.     

紫外线加速耐候试验机校准装置的设计

通过对紫外线加速耐候试验机老化原理的分析，针对紫外线加速耐候试验机的温度、湿度、紫外线中心波长和紫外线辐照度四个参数，设计了紫外线加速耐候试验机校准装置。装置采用STM32单片机为下位机核心，采集温度、湿度、紫外线中心波长和紫外辐照度四个参数，总共12个传感器模块的数据，通过USR-WIFI232模块进行无线数据传输以及各模块地址分配。将采集的数据发送到上位机LabVIEW2018软件开发平台，实现参数的多点实时在线显示、数据存储、生成表格等功能。此装置实现的技术指标，满足对于紫外线加速耐候试验机相关参数的校准要求。     

矿用本安型温度传感器测量系统的校准方法

矿用本安型温度传感器适用于煤矿机电设备的温度连续测量,传感器配测量系统则实现了现场设备温度数据多通道采集及存储功能。文章介绍了矿用本安型温度传感器测量系统的原理和校准方法,采用比较法对矿本安型温度传感器进行校准,通过校准对其测量系统的运算参数进行修正确定,对校准结果的不确定度评定和影响量分析,确定误差来源及减小误差影响的方法。进一步确定矿用本安型温度传感器测量系统的计量性能,保证工业现场测量的可靠性、稳定性。     

1590超级测温仪自动测试系统的开发

1590超级电阻测温仪采用的软盘数据存储设备与目前的主流计算机不兼容导致数据无法即时存储,因此开发了基于1590超级电阻测温仪的数据采集、控制和数据处理软件平台,组成基于1590超级电阻测温仪的自动测试系统.通过该软件平台可以在PC机上自动设置1590超级电阻测温仪的参数,实时显示测量数据,可同时观察多个通道温度/电阻随时间变化的测量曲线并自动存储测量数据.应用该系统可以进行固定点容器温坪复现过程的监控分析、温度回升监测报警,高精密铂电阻温度计校准处理,高精密恒温槽、定点炉、干井炉的温度场均匀性和稳定性的测试与分析.     

山东赛格测试仪器有限公司

正SG-820型非接触多功能速度仪由非接触光电传感器或GPS速度传感器作为测速单元,实时测试机动车的运动速度、距离等参数,采用大尺寸LED高亮显示屏,配合笔记本电脑可对测试过程的数据进行实时显示、存储及查询,软件采用WINDOWS界面,便于操作。适用于多种超速监测系统的首次检定、后续检定和使用中检验,也适用于便携式制动性能测试仪的动态校准。     

基于LabVIEW的信号发生器自动校准系统

本文介绍了基于LabVIEW的信号发生器自动校准系统的设计过程.利用计算机通过GPIB接口与信号源发生器及测试接收机进行通讯,根据测试接收机8902A的编程指令控制其接收信号源指令,在计算机上实时显示测量结果,利用LabVIEW自身的函数功能对数据进行存储及报表打印,从而构建功能完善的自动校准系统.     

Quantitative LC-MS of polymers: determining accurate molecular weight distributions by combined size exclusion chromatography and electrospray mass spectrometry with maximum entropy data processing

We report on the successful application of size exclusion chromatography (SEC) combined with electrospray ionization mass spectrometry (ESI-MS) and refractive index (RI) detection for the determination of accurate molecular weight distributions of synthetic polymers, corrected for chromatographic band broadening. The presented method makes use of the ability of ESI-MS to accurately depict the peak profiles and retention volumes of individual oligomers eluting from the SEC column, whereas quantitative information on the absolute concentration of oligomers is obtained from the RI-detector only. A sophisticated computational algorithm based on the maximum entropy principle is used to process the data gained by both detectors, yielding an accurate molecular weight distribution, corrected for chromatographic band broadening. Poly(methyl methacrylate) standards with molecular weights up to 10 kDa serve as model compounds. Molecular weight distributions (MWDs) obtained by the maximum entropy procedure are compared to MWDs, which were calculated by a conventional calibration of the SEC-retention time axis with peak retention data obtained from the mass spectrometer. Comparison showed that for the employed chromatographic system, distributions below 7 kDa were only weakly influenced by chromatographic band broadening. However, the maximum entropy algorithm could successfully correct the MWD of a 10 kDa standard for band broadening effects. Molecular weight averages were between 5 and 14% lower than the manufacturer stated data obtained by classical means of calibration. The presented method demonstrates a consistent approach for analyzing data obtained by coupling mass spectrometric detectors and concentration sensitive detectors to polymer liquid chromatography.     

Application of pattern recognition to mass spectral data of toxic organic compounds in ambient air

The low resolution mass spectra of a set of 78 toxic, volatile organic compounds, the presence of which is routinely monitored in ambient air samples, were examined for information concerning chemical classes and compound identification. The mass spectra were converted to their autocorrelation spectra, and the transformed spectra were studied using pattern recognition techniques. The inherent structure of the data showed three major classes: nonhaloaromatics, chlorocarbons, and bromo- and bromochlorocarbons. Principal components models, with dimensionality obtained with a cross-validation technique, contained two or three dimensions. Classification accuracy for the training set compounds was high. A hierarchical classification scheme, using statistical pattern recognition and k-nearest neighbor methods, was developed for chemical class assignment and for compound identification from mass spectral data files. The method was applied to gas chromatography—mass spectral data of known compounds of calibration sets obtained on the air quality monitoring mass spectrometer. Classification accuracy as to chemical class was 87% and compound identification accuracy was 84% for the calibration data. A classification scheme, which could be the basis for a microcomputer based expert system for mass spectral interpretation, is described.     

Solidification of phase change material on vertical cylindrical surface in holdup air bubbles

Solidification of phase change material around a vertical cylindrical surface was studied to investigate the performance of ice storage system and stored thermal energy. Air bubbles were generated in the phase change material at various air flow rate as a gas holdup to enhance the heat transfer rate and accelerate the ice layer growth at the solid–liquid interface. The test tube surface was cooled by ethylene glycol–water solution at a flow rate of 40% concentration by weight. The ice layer growth and solidification front velocity at solid–liquid interface were estimated from the temperature–time recorded data of a set of thermocouples fixed in a radial position perpendicular to cooled surface. The ice layer growth at the first instants of solidification process is much higher. Thereafter it decreased gradually according to the increasing of thermal resistance of ice layer. The increasing of ethylene glycol–water solution mass flow rate seems to accelerate the solidification process with small rate. The effect of air bubbles agitation was found to increase the ice layer growth rate and solidification front velocity by about of 20–45%. As a consequence the stored thermal energy was increased by about 55–115% with increasing air bubbles flow according to the attribute of generates turbulence at the solid–liquid interface. The measured data showed that with stirring the bulk water in energy storage tank, the storage time can be reduced by 10–35% of that without stirring.     

一种皮秒单光子计数光谱仪数据采集系统

针对皮秒时间相关单光子计数光谱仪中多道分析仪传输速率不高的情况,在荧光光谱测量中的多道定标技术的基础上,提出了采用 PCI 总线的数据采集卡改进方案。该方案以存储器中不同的地址作为测量中不同的道,将以 FPGA 实现的高速计数器按选定时间间隔的计数结果存入相应道中,存储器中数据经 PCI 总线读入内存并分析处理,从而取代原系统中的多道分析仪。实验结果显示,数据采集卡传输速率达到 20MB/s,比多道分析仪提高了 200 倍。     

A CFD Study on a Calibration System for Contact Temperature Probes

Surface-temperature measurements by means of contact probes require a detailed investigation of the probe-surface interaction. For an accurate calibration of such probes, the heat transfer processes involved in contact measurements must be well known and the impact of any influence parameters must be taken into account. At present, contact probes are generally calibrated by means of a temperature-controlled hot plate. A calibration system for contact surface-temperature probes, based on such a hot plate, was developed at INRIM. It covers the temperature range from ambient to 350 °C. The reference temperature is available on the upper surface of a metal block and is determined by linear extrapolation of the readings of three calibrated thermometers embedded into the block at different depths. However, the actual temperature of the reference surface largely depends on the sensor-to-surface interaction. The contact thermal resistance, the thermal conductivity of the block, the geometry of the probe, and the temperature of the surrounding fluid are just some of the parameters that affect a calibration and that may cause measurement errors if they are not properly taken into account and corrected for. Better insight into the interaction between the surface and the probe is therefore required. Since the experimental evaluation of measurement errors is not straightforward, mathematical modeling could represent a crucial tool to better understand the interactions between the probe and the calibration system. In this paper, a finite-element numerical model of the INRIM calibration system was developed in order to investigate the temperature field across the reference block as well as on its surface during a calibration. The thermal load introduced by a commercial contact probe during a calibration was also included in the simulation and its effect on the temperature field was studied. In order to obtain a detailed mathematical model, the surrounding air was also included in the simulation, avoiding the imposition of boundary conditions at the interface between solid parts and fluid. The proposed model was validated by comparing the results obtained with the available experimental data.     

Demonstration of proton-transfer reaction time-of-flight mass spectrometry for real-time analysis of trace volatile organic compounds

A proton-transfer reaction mass spectrometer based on time-of-flight mass spectrometry is described. This instrument couples a radioactive ion source and drift tube with a reflectron time-of-flight mass spectrometer. Volatile organic compounds in the gas phase with concentrations at the parts per billion by volume level can be detected in a matter of seconds, and crucially, the multichannel data acquisition in TOF-MS means that this detection sensitivity is available in all mass channels simultaneously. The typical mass resolution (m/Deltam) is in excess of 1000. The performance of the instrument is demonstrated using urban air measurements and a linear response/calibration test.     

用于量值传递的高精度单晶硅球质量测量研究

基于单晶硅球与现行常用砝码的物理特性差异,提出空气浮力修正改进计算方法.通过对硅球质量测量时空气密度瞬态变化分析,得出单次测量序列中存在6种不同空气密度变化序列,根据不同精度等级测量对各环境参数变化限值的要求,利用CIPM公式计算环境条件动态变化下的空气密度变化量,分析得出即使在恒温恒湿精密实验室下开展测量,相邻2次测...     

Matrix-assisted laser desorption/ionization mass spectrometry of discrete mass poly(butylene glutarate) oligomers

The mass dependency of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) response has been studied using equimolar mixtures of synthetic discrete mass poly(butylene glutarate) (PBG) oligomers of known structure having degrees of polymerization of 8, 16, 32, and 64. Mass discrimination observed was attributed to choice of matrix and detector saturation caused by higher laser intensity and inclusion of matrix ions in the MALDI spectra. Optimization of sample preparation and instrumental parameters provided uniform response over the mass ranged spanned by these four oligomers. The oligomer mixture was shown to serve as a model of more complex polymer distributions in the mass range 780-6000 Da, and application of the discrete mass oligomers as internal and calibration standards was demonstrated. Inclusion of PBG discrete mass oligomers as an internal standard in a quasi-equimolar mixture with polydispersed poly(butylene adipate) (PBA) indicated that some diminution of response occurred during the analysis of this mixture of materials. Reasons for differences in the corrected molecular weight averages of the polydispersed PBA obtained from measurements using MALDI and GPC were studied using individual discrete mass oligomers as calibration standards for GPC. The data indicated that differences in hydrodynamic volumes of PBG oligomers and PEG standards at similar masses resulted in an overestimation by GPC of the molecular weight averages of the PBA distribution.     

The Possibility and Importance of Increasing the Accuracy of Constricting Devices for Gases Taking into Account Experience in Investigating a Flowmeter with a Swivel Plate

The results of calibration tests on an air flowmeter instrument with a swivel plate are described. A flowmeter with changeable critical nozzles, calibrated on a test weight flowmeter instrument for gases, is used as the standard means of measurement.