Analysis of measurement uncertainty sources in the casting process

The concepts used in metrology are increasingly part of the productive process of metallurgical companies, considering the globalization of the world market. The interpretation of metrological concepts and their application in decision-making is still a challenge for the industry, especially for the measurement uncertainty calculation. Industries in the casting area are in great need of skilled labor both in relation to the productive process and engineering, as well as in metrology, highlighting the interdisciplinary of the concepts studied in the technical or baccalaureate courses. Therefore, the main objective of this work is to perform a brief literature review of publications made using the value of uncertainty of measurement within the production process of foundries. The results show that there is a potential research in the field, to which it relates the values of measurement uncertainty and fused components.

The New Dimension to Resolution: Can it be resolved?

In the metrology community, there is an ongoing debate over which contributors to the Unit Under Test (UUT) belong in the expanded uncertainty calculation of the measurement process used for calibration. This is also known as Calibration Process Uncertainty (CPU); CPU is the denominator when calculating a Test Uncertainty Ratio (TUR). This paper presents examples that illustrate why the best practices outlined in documents such as ILAC-P14:09/2020 and the ANSI/NCSLI Z540.3 Handbook should be followed regarding the contributors for the CPU. Instead of drafting their own test protocols and standards, calibration laboratories and manufacturers are advised to correctly calculate both uncertainty and risk. Performing these calculations is part of an ethical approach to calibration that avoids shifting more risk to the Industry and ultimately mitigates global consumer's risk. Furthermore, outdated approaches to calculations, such as Test Accuracy Ratio (TAR), must be discontinued, and efforts to change the agreed-upon definition of Test Uncertainty Ratio (TUR) should cease since modern computing can provide measurements that are more accurate and reliable.

Uncertainty of factor Z in gravimetric volume measurement

<p class="Abstract">In the gravimetric volume measurement method, the factor <em>Z</em> is generally used to facilitate an easy conversion from the apparent mass obtained using a balance to the liquid volume. The uncertainty of the measurement used for the liquid volume can be divided into two specific contributions: one from the components related to the mass measurements and one from those related to the mass-to-volume conversion. However, some ISO standards and calibration guides have suggested that the uncertainty due to the factor <em>Z</em> is generally neglected in the uncertainty calculation pertaining to gravimetric volume measurement. This paper describes the combined effects of the density of the water, the density of the reference weights, and the air buoyancy on the uncertainty of factor <em>Z</em> in terms of how they subsequently affect the uncertainty of the measurement results.</p>

UNCERTAINTY QUANTIFICATION USING THERMOCOUPLE AND ARDUINO® COMPATIBLE HARDWARE

Temperature is a critical aspect in the control of processes in engineering. The measurement, however, must take into account not only the accuracy of the sensor but also the implementation costs and uncertainty. Thermocouples are one of the most widely used temperature measurement methods combining low costs, high measurement ranges, and relatively good accuracy. The acquisition system, however, is usually expensive. This paper evaluated the uncertainty in the temperature measurements of a K-type thermocouple using low cost Arduino® compatible hardware as a data acquisition system. This set was calibrated using a thermostatic distilled water bath at both freezing and boiling phase change points. The equations for uncertainty calculation were fully developed, and the procedures described serve as a reference for uncertainty assessment for thermocouples with other data acquisition systems. Although the calibration was the most significant contributor, the low variability of measurements shows the system has good stability and is a fine choice for industrial applications. The calculations are easy to implement as a routine for several measurements and guarantee results up to the international reference standard.

Two approaches for measurement uncertainty estimation: which role for bias? Complete blood count experience

Objectives Measurement uncertainty is described as a magnitude indicates the distribution of the measurement results. AACB Guideline suggests that bias should not be included in the uncertainty calculation contrary to Nordtest Guideline. The aim of the study is to calculate the uncertainty values of certain complete blood count (CBC) parameters and evaluate the contribution of bias. Methods This retrospective study was performed with the quality control data of January–December 2017 of two different CBC autoanalyser models (Beckman Coulter LH780 and DXH800). Measurement uncertainties were calculated according to AACB and Nordtest Guidelines. Imprecision, i.e. measurement uncertainty, varies with concentration. Imprecision values of user manuals, as performance characteristics of autoanalyzers, were used for assessment. Results User manuals imprecision values of different levels of platelets are between 3.3 and 14%. As the concentrations of platelets decrease, imprecision is observed to increase. This is expected to be parallel with measurement uncertainty. Contrary to user manuals, uncertainty values of AACB found to be so close to each other (between 3.41% and 4.80%), regardless of concentration level. However Nordtest guideline is more compatible with user manuals (between 6.97% and 15.35%). Conclusions When evaluated with the performance expectations, bias should be used in measurement uncertainty. Calculation of uncertainty for different concentration level is also important. Amaç Ölçüm belirsizliği, bir büyüklük olarak ölçüm sonuçlarının dağılımını ifade eder. AACB Kılavuzu, Nordtest Kılavuzunun aksine, biasın belirsizlik hesaplamasına dahil edilmesini önermemektedir. Çalışmanın amacı, belirli tam kan sayımı (CBC) parametrelerinin belirsizlik değerlerini hesaplamak ve biasın katkısını değerlendirmektir. Gereç ve Yöntemler Bu retrospektif çalışma, iki farklı CBC otoanalizör modelinin (Beckman Coulter LH780 ve DXH800) Ocak-Aralık 2017 kalite kontrol verileriyle gerçekleştirildi. Ölçüm belirsizlikleri AACB ve Nordtest Kılavuzlarına göre hesaplandı. İmpresizyon, dolayısıyla ölçüm belirsizliği, konsantrasyona göre değişir. Belirsizlik sonuçlarını değerlendirmede otoanalizörlerin kullanım kılavuzlarında yer alan impresizyona dayalı performans özellikleri kullanılmıştır. Bulgular Farklı trombosit düzeylerinin kullanım kılavuzlarındaki impresizyon değerleri %3.3-%14 arasındadır. Trombosit konsantrasyonu düştükçe impresizyon artar. Bunun ölçüm belirsizliği ile paralel olması beklenir. Kullanım kılavuzlarının aksine, AACB’ye göre hesaplanan belirsizlik değerleri, konsantrasyon seviyesinden bağımsız olarak birbirine çok yakın (%3.41–%4.80 arasında) bulundu. Bununla birlikte, Nordtest kılavuzunun sonuçları,otoanalizörlerin kullanım kılavuzları ile daha uyumlu bulundu (%6.97–%15.35 arasında). Sonuç Performans beklentileri ile değerlendirildiğinde, ölçüm belirsizliğinde bias kullanılmalıdır. Farklı konsantrasyon seviyeleri için belirsizliğin ayrı ayrı hesaplanması da önemlidir.

Validation Method on Determination of Chemical Oxygen Demand Using Indirect UV-Vis Spectrometry

The validation method for determination of chemical oxygen demand (COD) with indirect UV-Vis spectrometry have been done. This method enable to easily perform highly sensitive, considerably faster and easier, and minimize the use of digestion solution. This method is the development of standard method of COD determination by closed reflux using UV-Vis spectrometry so it requires the method validation stage. The validation is used to ensure linearity, limit of detection, limit of quantification, precision, and accuracy values in accordance with quality control. This study was also carried out to formulate the uncertainty calculation modeling of COD on water analysis. The result of validation method show that the calibration curve linearity is 0.9994 with the linear regression equation Y = 0.0003X + 0.0005. The method is able to have high sensitivity in measuring COD value with low concentrations with limit of detection and limit of quantitation of 9.78 and 32.59 mg O2/L. Indirect UV-Vis spectrometry has high precision with relative standard deviation of 0.66% and high accuracy with the percentage of recovery of 91.35%. The uncertainty formulation model on determination of COD from the source of standard uncertainty of sample volume, calibration curves, and repeatability.

Embracing Uncertainty: Modeling Uncertainty in EPMA—Part II

This, the second in a series of articles present a new framework for considering the computation of uncertainty in electron excited X-ray microanalysis measurements, will discuss matrix correction. The framework presented in the first article will be applied to the matrix correction model called “Pouchou and Pichoir's Simplified Model” or simply “XPP.” This uncertainty calculation will consider the influence of beam energy, take-off angle, mass absorption coefficient, surface roughness, and other parameters. Since uncertainty calculations and measurement optimization are so intimately related, it also provides a starting point for optimizing accuracy through choice of measurement design.