系统误差分析及其减小方法

通过对系统误差分析,提出了系统测量的误差来源修正及控制误差的方法,供系统测量工作者参考。     

丙烯酸装置中界面测量系统分析——浮力式测量的温度修正方法

本文对丙烯酸装置中萃取塔界面测量系统进行了全面分析，对用浮力式液面计测量界面的原理、系统的误差、温度补偿公式和原理进行了研究探讨。对其温度补偿公式中的系数计算方法进行了推算、反证。为界面测量系统在智能仪表与集散控制系统中应用温度补偿技术提供了计算方法。     

仪表工试题

1.有一测量系统,测量元件的误差为±1.5％,变送器的误差为±0.5％,记录仪的误差为±1％,问系统的总误差为多少? 解:系统总误差为系统中各元件误差的几何和,即△=±(sum from i=1 to n α_i~2)~(1/2)％ =±(1.5~2 0.5~2 1~2)~(1/2)％     

节点与测量数据组合检测的数据协调及应用

提出一种新型的节点与测量数据组合检测的稳态数据协调方法。该方法通过节点检测法和测量检测法共同检测可能存在显著误差的可疑节点,以及与可疑节点相连的最可疑测量变量,并通过调整量检测法融合领域专家的先验知识判断最可疑测量变量是否存在显著误差,最终实现稳态数据协调和显著误差同步检测。该组合方法融合测量检测和节点检测方法的各自优点且克服各自的缺点。仿真研究与实际应用表明,该组合方法对有多个显著误差的系统也能给出准确的显著误差检测结果,且优于迭代测量检测方法。     

万用表的量程选择及测量误差分析

用万用表进行测量时会带来一定的误差。这些误差有些是仪表本身的准确度等级所允许的最大绝对误差,有些是调整、使用不当带来的人为误差。正确了解万用表的特点以及测量误差产生的原因,掌握正确的测量技术和方法,就可以减小测量误差。     

差压（压力）式液位检测误差的修正

介绍了用差压(压力)式方法检测液位而形成的误差，主要是因温度变化引起密度的改变造成的，并且对仪表检测并显示的测量系统及微机检测系统的修正方法进行了介绍。     

检测陶瓷墙地砖误差的计算机系统的设计

本文介绍了对陶瓷墙地砖综合误差进行测量的电子检测系统的设计,阐述了其系统组成、检测原理和数据处理等方面。这种检测系统对于提高瓷砖误差检测的准确性和效率具有实际意义。     

智能仪表在蒸汽流量测量中的应用

本文分析了常规仪表组成的简单测量系统测量蒸气流量产生较大误差的原因,提出了减小误差的方法,简要介绍了智能流量仪的工作原理及在蒸汽流量测量中的应用。     

LNG到港交接计量的影响因素及误差核定

液化天然气到港交接受到温度、压力等多种影响,在交接过程中需要对多个参数进行测量。测量过程必然会产生误差并随着过程的推进而逐步累积。在此种情况下,探讨误差的来源、影响因素及具体的核定具有多重意义。因此,在总结了计量方式及计算规则的基础上,对误差的来源及影响因素进行了系统分析。并通过实例计算的方式探讨不同误差对总误差的占比发现,液态体积测量过程以及甲烷含量测量过程中产生的误差最大,分别达到86.07%和31.51%,二者可以共同解释误差变量大于85%适宜于作为误差计算的标志性指标。     

远传差压液位测量受环境温度影响的误差分析

分析因环境温度变化,利用隔膜密封系统在测压过程中存在偏差的原因,通过实例计算,对对称与非对称式远传差压液位测量系统进行误差的比较和分析,提出液位测量系统的选型建议。     

污垢热阻实时预测模型校正与应用

针对热阻法污垢热阻预测模型在操作条件变化较大时存在很大的原理误差,不能用于污垢实时监测的问题,提出了一种对热阻法污垢热阻预测模型的校正方法。实验研究表明,校正模型原理误差小于3.5%。并针对热学法污垢热阻测量误差与结垢程度有关的特点,推导了测量误差计算式,提出测量误差实时跟踪的测量方法,依据误差值判断测量结果的有效性,提高对高污垢热阻阶段监测结果的可靠性。应用于煤油冷却器的实时监测,表明测量可靠。     

BP神经网络补偿快速成型系统闭环误差的研究

提出快速成型系统闭环误差反馈的必要性,将BP神经网络引入快速成型技术,建立了快速成型误差补偿模型,探求出一种快速成型系统闭环误差的反馈方法,并通过实例进行了验证。结果表明,基于BP神经网络控制的最大绝对误差和相对误差均比传统误差补偿方法大为降低。     

气相声速测量偏差对导出热力学性质的影响

气相声速是测量准确度最高的热物性之一,并可以导出理想气体比定压热容和第二维里系数等其他热力学性质。分析了定程干涉法中存在的系统偏差,建立了绝对系统偏差（δ_FAE）和相对系统偏差（δ_FFE）对导出热力性质影响的数学模型,并开展了模拟计算。研究结果表明,理想气体比热容比受绝对系统偏差的影响为2δ_FAE,但是绝对系统偏差对多原子气体的理想气体比定压热容的影响大,可高于-100δ_FAE,且温度越高,影响越大;相对系统偏差主要影响声速维里系数,在温度和相对系统偏差相同时,不同工质的第二声速维里系数的绝对变化量相同。绝对系统偏差和相对系统偏差在导出第二维里系数中的影响较小。     

On the Determination of Continuous Submicrometer Liquid Aerosol-Size Distributions with Low Pressure Impactors

The aspects associated with the determination of continuous submicrometer aerosol-size distributions using multijet low pressure impactors have been studied. Multiple sets of error-free and noisy, simulated data sets have been inverted, and impactors have been compared with the differential mobility particle-size analysis (DMA) method by using well-defined, laboratory-generated liquid oleic acid aerosols tagged with ammonium fluorescein. Impactors included in this study were a Berner-type impactor HAUKE 25/0.015 (BLPI), a modified University of Washington Mark 5 impactor (KLPI), and the impactor designed at the University of Florida (LLPI). The inversion of simulated error-free impactor data (i.e., the data with perfect kernel functions) for unimodal submicrometer aerosols with a small (2.5%) stage mass error estimate yields results very close to input distributions, when the method based on constrained regularization is used in the inversion. When the error estimate is increased, inverted spectra are flattened. However, they remain clearly unimodal. When normally distributed random error is added to the data and the error estimate for each data point equals the standard deviation of the random error, the fraction of bimodal and trimodal inverted spectra increases with a rise in the random error level and with the asymmetricity of the kernel functions. When the random error level and data error estimates are equal to or smaller than 10%, inverted spectra are mainly unimodal close to input distribution for both error-free and noisy data. The inversion of impactor data from the detailed laboratory experiments (i.e., the data with real kernel functions) indicates that only BLPI kernel functions are accurate enough to yield unimodal distributions close to those measured with the DMA. When the stage mass error estimate is increased beyond the stage mass determination error, unimodal spectra also for the KLPI and LLPI are found. The decrease of the BLPI stage mass error estimate below the experimental error increases the agreement with DMA results. In most cases the error estimate for BLPI stage masses can be decreased to 2.5%, indicating the validity of both BLPI submicrometer kernel functions and the fluorometric method used to determine stage mass concentrations.The aspects associated with the determination of continuous submicrometer aerosol-size distributions using multijet low pressure impactors have been studied. Multiple sets of error-free and noisy, simulated data sets have been inverted, and impactors have been compared with the differential mobility particle-size analysis (DMA) method by using well-defined, laboratory-generated liquid oleic acid aerosols tagged with ammonium fluorescein. Impactors included in this study were a Berner-type impactor HAUKE 25/0.015 (BLPI), a modified University of Washington Mark 5 impactor (KLPI), and the impactor designed at the University of Florida (LLPI). The inversion of simulated error-free impactor data (i.e., the data with perfect kernel functions) for unimodal submicrometer aerosols with a small (2.5%) stage mass error estimate yields results very close to input distributions, when the method based on constrained regularization is used in the inversion. When the error estimate is increased, inverted spectra are flattened. However, they remain clearly unimodal. When normally distributed random error is added to the data and the error estimate for each data point equals the standard deviation of the random error, the fraction of bimodal and trimodal inverted spectra increases with a rise in the random error level and with the asymmetricity of the kernel functions. When the random error level and data error estimates are equal to or smaller than 10%, inverted spectra are mainly unimodal close to input distribution for both error-free and noisy data. The inversion of impactor data from the detailed laboratory experiments (i.e., the data with real kernel functions) indicates that only BLPI kernel functions are accurate enough to yield unimodal distributions close to those measured with the DMA. When the stage mass error estimate is increased beyond the stage mass determination error, unimodal spectra also for the KLPI and LLPI are found. The decrease of the BLPI stage mass error estimate below the experimental error increases the agreement with DMA results. In most cases the error estimate for BLPI stage masses can be decreased to 2.5%, indicating the validity of both BLPI submicrometer kernel functions and the fluorometric method used to determine stage mass concentrations.The aspects associated with the determination of continuous submicrometer aerosol-size distributions using multijet low pressure impactors have been studied. Multiple sets of error-free and noisy, simulated data sets have been inverted, and impactors have been compared with the differential mobility particle-size analysis (DMA) method by using well-defined, laboratory-generated liquid oleic acid aerosols tagged with ammonium fluorescein. Impactors included in this study were a Berner-type impactor HAUKE 25/0.015 (BLPI), a modified University of Washington Mark 5 impactor (KLPI), and the impactor designed at the University of Florida (LLPI). The inversion of simulated error-free impactor data (i.e., the data with perfect kernel functions) for unimodal submicrometer aerosols with a small (2.5%) stage mass error estimate yields results very close to input distributions, when the method based on constrained regularization is used in the inversion. When the error estimate is increased, inverted spectra are flattened. However, they remain clearly unimodal. When normally distributed random error is added to the data and the error estimate for each data point equals the standard deviation of the random error, the fraction of bimodal and trimodal inverted spectra increases with a rise in the random error level and with the asymmetricity of the kernel functions. When the random error level and data error estimates are equal to or smaller than 10%, inverted spectra are mainly unimodal close to input distribution for both error-free and noisy data. The inversion of impactor data from the detailed laboratory experiments (i.e., the data with real kernel functions) indicates that only BLPI kernel functions are accurate enough to yield unimodal distributions close to those measured with the DMA. When the stage mass error estimate is increased beyond the stage mass determination error, unimodal spectra also for the KLPI and LLPI are found. The decrease of the BLPI stage mass error estimate below the experimental error increases the agreement with DMA results. In most cases the error estimate for BLPI stage masses can be decreased to 2.5%, indicating the validity of both BLPI submicrometer kernel functions and the fluorometric method used to determine stage mass concentrations.The aspects associated with the determination of continuous submicrometer aerosol-size distributions using multijet low pressure impactors have been studied. Multiple sets of error-free and noisy, simulated data sets have been inverted, and impactors have been compared with the differential mobility particle-size analysis (DMA) method by using well-defined, laboratory-generated liquid oleic acid aerosols tagged with ammonium fluorescein. Impactors included in this study were a Berner-type impactor HAUKE 25/0.015 (BLPI), a modified University of Washington Mark 5 impactor (KLPI), and the impactor designed at the University of Florida (LLPI). The inversion of simulated error-free impactor data (i.e., the data with perfect kernel functions) for unimodal submicrometer aerosols with a small (2.5%) stage mass error estimate yields results very close to input distributions, when the method based on constrained regularization is used in the inversion. When the error estimate is increased, inverted spectra are flattened. However, they remain clearly unimodal. When normally distributed random error is added to the data and the error estimate for each data point equals the standard deviation of the random error, the fraction of bimodal and trimodal inverted spectra increases with a rise in the random error level and with the asymmetricity of the kernel functions. When the random error level and data error estimates are equal to or smaller than 10%, inverted spectra are mainly unimodal close to input distribution for both error-free and noisy data. The inversion of impactor data from the detailed laboratory experiments (i.e., the data with real kernel functions) indicates that only BLPI kernel functions are accurate enough to yield unimodal distributions close to those measured with the DMA. When the stage mass error estimate is increased beyond the stage mass determination error, unimodal spectra also for the KLPI and LLPI are found. The decrease of the BLPI stage mass error estimate below the experimental error increases the agreement with DMA results. In most cases the error estimate for BLPI stage masses can be decreased to 2.5%, indicating the validity of both BLPI submicrometer kernel functions and the fluorometric method used to determine stage mass concentrations.     

天然气输差问题的分析与研究

输差是控制输气成本的一个最关键的指标,如何降低输差是管输企业面临的难题。针对输气系统的输差问题,从误差理论出发,以输气干线系统为研究对象,分析了产生输差问题的原因,对标准孔板引起的测量误差、输气干线测量误差和测量误差造成的输差进行了计算,给出了单点输差和综合输差的计算方法,并提出了降低输差的措施和方法。     

聚酯切片b值测定结果的误差分析及对策

从系统误差和随机误差2个方面对影响聚酯切片b值测定结果的各种因素进行分析，采取了相应的对策，可以消除各种误差产生来源，测定结果重复性好，正确反映出产品品质。     

均匀性试验抽样误差的蒙特卡罗模拟

对现行均匀性试验抽样误差和扩大样本容量后的抽样误差,应用蒙特卡罗方法进行数值模拟。结果表明,当总体标准偏差为1.5MPa,样本容量为10,对应水泥28d抗压强度分别为40MPa、50MPa和60MPa时,以变异系数表示的抽样误差分别为1.7%、1.4%和1.1%。这个误差很大,可能导致对水泥均匀性的错误评价。根据扩大样本容量后的抽样误差模拟结果,提出了均匀性试验抽样方法的修改建议。     

Control relevant on‐line model validation criterion based on robust stability conditions

This paper is concerned with detection and diagnosis of modelling error under closed‐loop conditions. The effect of modelling error on process output error (which is the error between the process output and the simulated output) is first analysed. Then robust stability conditions for on‐line model validation are applied. The main premise is that whenever the closed‐loop system violates the robust stability condition, it is a sign of significant process change and a signal that the control system may become potentially unstable. We relate the process output error with robust stability conditions and introduce three propositions for on‐line model validation. Any process change (or modelling error) that makes the system violate the condition specified by the robust stability theorem can be detected. Simulation examples are presented to demonstrate the applicability of the propositions. An index is also proposed to quantify modelling error in frequency domain. Simulation examples and an experimental case study are presented to demonstrate the use of the new index.     

测量仪表过失误差的单结点识别方法

提出了一种新的过失误差识别方法 ,即结合仪表的可靠度、精度等级等信息 ,利用单结点的约束残差进行过失误差识别 .给出仿真实例 ,通过与其他几种常用的误差识别方法对比对这一方法进行了评价 .     

Sources of error in determination of available lysine in cottonseed and peanut meals

Experiments were made to identify the sources of error in the Rao procedure for available lysine in cottonseed and peanut meals and to estimate the magnitude of each. The partition of squares in analyses of variance of the data reported revealed that the major error can be attributed to sampling. The variances due to other possible sources of error, such as dinitrophenylation, hydrolysis, chromatography, etc., were not significantly different from the error variance, which (after the sampling error is accounted for) corresponds to confidence limits at the 5% level of probability of ±0.5% of the mean of the available lysine concentration. ARS, USDA.