浅谈测量误差与不确定度

本文对测量误差和测量不确定度的定义、来源及分类进行描述。通过对测量误差和测量不确定度的区别及比较,阐述了用测量不确定度取代测量误差评定测量结果的必然性。     

砝码磁性的测量及不确定度分析

随着电子天平的广泛采用，因为大多数电子天平都采用电磁平衡原理，砝码与电子天平之间将产生相互磁力作用，了解砝码的磁性，降低砝码磁性对电子天平的作用，越来越引起我们的重视。本文详细阐述了国际建议推荐的几种砝码磁化率的测量方法，最后以磁化率计法为例介绍了砝码磁化率的测量原理、方法及不确定度分析。了解砝码的磁性，即了解砝码与电子天平之间产生的相互磁力作用，故有利于提高称量结果的准确性。     

Artificial neural network prediction of aging effects on the wear behavior of IN706 superalloy

In this study, the effect of aging parameters on wear behavior of PM Inconel 706 (IN 706) superalloy was experimentally investigated and an ANN model was developed to predict weight loss after wear tests. IN 706 superalloy powders were cold pressed (700 MPa) and sintered at 1270 °C for 90 min. The sintered components were gradually aged for 16 h at 730 °C and for 12–20 h at 620 °C. The samples of IN706 superalloy were subjected to wear test at a constant sliding speed of 1 m/s under three different loads (30 N, 45 N and 60 N) and for five different sliding distances (400–2000 m). The results clearly showed that δ, γ′ and γ″ phases were observed around grain boundaries of IN 706 superalloy aged for different periods. The highest hardness was measured for the samples aged for 12 h. Weight losses were found to increase as the sliding distance increased. Moreover, the ANN modeling of weight loss values for IN 706 superalloy gave effective results and can be successfully used to predict weight loss values in the parameters that were determined by the obtained high R² value.     

混凝土抗压强度测量不确定度评定

混凝土抗压强度试验是评定混凝土工程质量的重要手段，通过对混凝土抗压强度测量结果不确定度评定，分析了荷载、试件截面尺寸、检验重复性、数据修约等影响测量结果不确定度的因素和来源，对各分量进行了计算合并，并作出了评定，为提高测量水平提供指导。     

小麦粉中偶氮甲酰胺含量测量的不确定度评定

分析了高效液相色谱法测定小麦粉中偶氮甲酰胺含量不确定度的各分量,对其测量不确定度进行合理的评定,结果表明:小麦粉样品中偶氮甲酰胺的含量为43.1mg/kg时,其扩展不确定度为2.6 mg/kg(k=2),不确定度主要是最小二乘法拟合标准工作曲线求得样品浓度过程引入的。     

产品质量检测不确定度的分析及应用

本文对测量误差和测量不确定度的基本概念作了简单介绍，得出测量结果的可靠程度是通过分析和评定测量不确定度来确定的；本文着重介绍和探讨了测量不确定度的计算步骤和计算方法，并结合电气实验室经常遇到的电压测量给出不确定度分析和计算实例；本文还介绍了单次测量条件下如何利用已知条件进行不确定度的估计以及不确定度的应用范围。     

大米中镉含量的测量不确定度评定

分析了石墨炉原子吸收光谱法测定大米中镉含量不确定度的各分量,对其测量不确定度进行合理的评定,结果表明:大米样品中镉的含量为0.18 mg/kg时,其扩展不确定度为0.01 mg/kg(k=2),不确定度主要是最小二乘法拟合标准工作曲线求得样品浓度过程和测试过程随机效应引入的。     

球形金属罐容量测量结果不确定度的评定

依据JJC642-1990《球形金属罐容量国家计量检定规程》和JJF1059-1999（测量不确定度评定与表示国家计量技术规范》，对环形金属罐容量的测量结果不确定度进行评定。环形金属罐的测量采用光切法，通过分析中心距、水平夹角、左右切点天顶距等参数，计算球形金属罐容量测量结果的不确定度。可供从事球形罐检测工作的人员参考。     

Artificial neural network modelling to predict hot deformation behaviour of as HIPed FGH4169 superalloy

Abstract

The hot deformation behaviour of as HIPed FGH4169 superalloy was studied by single stroke compression test on MMS-200 test machine at the temperatures of 950–1050°C and the strain rates of 0·004–10 s^?1. Based on the experimental results, a back-propagation artificial neural network model and constitutive equation method were established to predict the flow stress of FGH4169 superalloy. The predictability of two different models was compared. The correlation coefficients of experimental and predicted flow stress with the trained BP ANN model and constitutive equation were 0·9995 and 0·9808 respectively. The average root mean square error (RMSE) values of the trained ANN model and constitutive equation are 0·39 and 2·21 MPa respectively. And the average absolute relative error (AARE) values of the trained ANN model and constitutive equation are 1·79 and 7·47% respectively. The results showed that the ANN model is an effective tool to predict the flow stress in comparison with constitutive equation.     

标准煤气表仪表系数测量不确定度分析

本文简略介绍了标准煤气表的测量方法，并依据JJG267-1996标准煤气表检定规程和JJF1059-1999测量不确定度评定与表示，对标准煤气表仪表系数测量结果进行不确定度的评定。具体分述各个不确定度分量（包括标准煤气表示值、气体流量标准装置通过的气体体积、装置内压力、标准煤气表前压力、装置内气温、标准煤气表前气温、装置内的饱和蒸汽压、标准煤气有处的饱和蒸汽压、装置内气体相对湿度、标准煤气表处的气体相对湿度）的产生，并合成标准不确定度及给出有效自由度。     

Addressing imperfect maintenance modelling uncertainty in unavailability and cost based optimization

Optimization of testing and maintenance activities performed in the different systems of a complex industrial plant is of great interest as the plant availability and economy strongly depend on the maintenance activities planned. Traditionally, two types of models, i.e. deterministic and probabilistic, have been considered to simulate the impact of testing and maintenance activities on equipment unavailability and the cost involved. Both models present uncertainties that are often categorized as either aleatory or epistemic uncertainties. The second group applies when there is limited knowledge on the proper model to represent a problem, and/or the values associated to the model parameters, so the results of the calculation performed with them incorporate uncertainty. This paper addresses the problem of testing and maintenance optimization based on unavailability and cost criteria and considering epistemic uncertainty in the imperfect maintenance modelling. It is framed as a multiple criteria decision making problem where unavailability and cost act as uncertain and conflicting decision criteria. A tolerance interval based approach is used to address uncertainty with regard to effectiveness parameter and imperfect maintenance model embedded within a multiple-objective genetic algorithm. A case of application for a stand-by safety related system of a nuclear power plant is presented. The results obtained in this application show the importance of considering uncertainties in the modelling of imperfect maintenance, as the optimal solutions found are associated with a large uncertainty that influences the final decision making depending on, for example, if the decision maker is risk averse or risk neutral.     

人工神经网络在电积锌工艺中的应用

本文提出了一种基于人工神经网络分析电积锌工艺的方法 ,通过仿真计算 ,表明这种方法切实可行     

新型直流电阻箱检定装置的不确定度评定

采用上海蓝斯汀仪表研究所生产的RT9608直流电阻校验仪和一套二等标准电阻,对ZX54型0.01级直流电阻箱×1000档第一点的测量结果的不确定度评定过程的阐述与分析,指出了影响测量结果的相关因素,并通过计算合成进行了评定。结果证明,该新型装置完全符合规程要求,自动化程度高,具有很广的应用前景。     

神经网络模型在预测Ni-Al系热爆点火时间中的应用

基于人工神经网络的原理,对热爆法制备Ni-Al系金属间化合物中的控制参数进行了研究,选取了加热速率、颗粒尺寸、压坯密度三个参数,通过对此参数的调控可以影响热爆反应的点火时间及反应过程.本文采用BP算法来训练网络,对热爆反应中的过程参数与热爆点火时间的映射关系进行了函数逼近,建立了热爆点火时间的神经网络模型.根据该模型可以预测热爆的点火时间,为控制热爆反应加压过程提供了可靠的依据.     

音速喷嘴气体流量标准装置测量不确定度评定

各种流量计从研制到使用，必须对其特性进行研究，对其标称的流量性能进行试验，并给出试验结果。这些试验研究工作都需要在流量标准装置上进行。因此，流量标准装置的不确定度直接关系到试验结果的水平，对其研究是非常必要的。用临界流文丘利喷嘴做为流量标准，用比较法原理对流量计进行检定和校准，音速喷嘴法气体流量标准装置可对各种气体流量计的检测和校准，并对其检定和校准结果的不确定度进行评定。     

电子天平测量结果不确定度的研究

为解决电子天平在测量过程中达到用测量不确定度来统一评价测量结果质量的问题,对电子天平测量结果不确定度进行了研究。依照电子天平复现质量之差的原理,采用分析误差源的方法,研究测量过程中用电子天平来复现质量,给测量结果引入不确定的范围。通过本方法的研究而得到电子天平测量结果不确定度,对电子天平测量结果的质量有了比较可靠的保证。     

转子流量计测量不确定度评定

本文讲述了转子流量计测量不确定度的评定。具体分述各个分量的产生     

滑板式汽车侧滑检验台示值误差测量结果的不确定度评定

本文依据JJG908-1996滑板式汽车侧滑检验台检定规程和JJF1059-1999测量不确定度评定与表示,对滑板式汽车侧滑检验台示值误差测量结果进行了不确定度的评定,通过阐述测量过程中产生的各分量对测量结果的影响,得到了测量结果的扩展不确定度。     

Prediction of compressive properties of closed-cell aluminum foam using artificial neural network

The design of artificial neural network (ANN) is motivated by analogy of highly complex, non-linear and parallel computing power of the brain. Once a neural network is significantly trained it can predict the output results in the same knowledge domain. In the present work, ANN models are developed for the simulation of compressive properties of closed-cell aluminum foam: plateau stress, Young’s modulus and energy absorption capacity. The input variables for these models are relative density, average pore diameter and cell anisotropy ratio. Database of these properties are the results of the compression tests carried out on aluminum foams at a constant strain rate of 1 × 10⁻³ s⁻¹. The prediction accuracy of all the three models is found to be satisfactory. This work has shown the excellent capability of artificial neural network approach for the simulation of the compressive properties of closed-cell aluminum foam.     

任意波形发生器测量标准不确定度评定

任意波形发生器不但可以输出标准信号,而且可以方便地产生复杂波形,以满足人们的需要。任意波形发生器各项参数是否准确直接影响到科研生产及企业的产品质量,因此需要对其各参数进行校准,而校准结果的质量直接关系到其量值传递准确与否,所以需要对其测量标准的测量能力进行评定,以确定校准装置是否满足校准要求。本文对任意波形发生器测量标准不确定度进行了分析评定。评定过程及结论可应用在计量标准进行相关特性的不确定度分析评定上。