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Abstract. Monte Carlo Simulation (MCS) and Expression of Uncertainty in Measurement (GUM) are the most common approaches for uncertainty estimation. In this work MCS and GUM were used to estimate the uncertainty of hardness measurements. It was observed that the resultant uncertainties obtained with the GUM and MCS without correlated inputs for Brinell hardness (HB) were ±0.69 HB, ±0.67 HB and for Vickers hardness (HV) were ±6.7 HV, ±6.5 HV, respectively. The estimated uncertainties with correlated inputs by GUM and MCS were ±0.6 HB, ±0.59 HB and ±6 HV, ±5.8 HV, respectively. GUM overestimate a little bit the MCS estimated uncertainty. This difference is due to the approximation used by the GUM in estimating the uncertainty of the calibration curve obtained by least squares regression. Also the correlations between inputs have significant effects on the estimated uncertainties. Thus the correlation between inputs decreases the contribution of these inputs in the budget uncertainty and hence decreases the resultant uncertainty by about 10%. It was observed that MCS has features to avoid the limitations of GUM. The result analysis showed that MCS has advantages over the traditional method (GUM) in the uncertainty estimation, especially that of complex systems of measurement. MCS is relatively simple to be implemented.

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In accordance with the recent version of ISO 376:2011, the classification of the force transducers is based on the relative errors calculated from the calibration results. This classification approach doesn't take the uncertainty of measurement into consideration. It becomes one of the most important factors that must be utilized when making a classification decision based on of ISO/IEC 17025:2017. In this study a proposed approach for force proving instrument classification was developed. This approach is based on taking into account the calibration results uncertainty of the instruments as a decision rule for classifications. Since the expanded budget uncertainty is a combination of different parameters that may affect the classifications decisions so it is more realistic and more accurate for decision making. The results of this paper demonstrate a recommendation for ISO 376:2011 to modify its classification criteria for the force proving instruments in the upcoming version of this standard.

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The indicated value on the displaying device of a digital measuring instrument is usually considered as the resultant of rounding the measurand value to the nearest indication. This hypothesis is conventional and forms the basis of estimating the resolution uncertainty associated with digital indications. However, the essential quantization process needed in converting the measurand analog signal into a digital form makes the precise estimation of the resolution uncertainty shift from the one based on the aforementioned hypothesis. In this study, the effect of the quantization process on the resolution uncertainty was analyzed, a proposed algorithm for the estimation process was presented, and finally the impact of noise presence was considered. Based on the current study, the measurement result usually has a shift from the indicated value. In the presence of noise, the resolution uncertainty of stable indications can be reduced if the peak-to-peak noise could be quantified with adequate accuracy.Also, the current study recommends the revision of the broad applicability of the conventional estimation method of the resolution uncertainty and encourages standardization bodies to specify the main requirements in digital measuring instruments that guarantee their indicating behavior.

A geogrid is geosynthetic high-density polyethylene material used to reinforce soils and similar materials. It is valuable tool in transportation and civil construction. Geogrids allow engineers to build where it otherwise would not be possible or would be cost prohibitive using traditional methods. The tensile test of the geogrid is the most important test of this product. ISO 10319 "Geosynthetics-Wide-Width tensile test" uses wide-width specimen 20 mm wide; the gripping of this wide sample is difficult and need special gripping. This study aims to develop and validate a method for testing single-rib specimen, instead of wide specimen using 150 samples of geogrids, and six different speeds. The statistical analysis of the results showed that testing of single rib at the speed of 100 mm/min (method under validation) gave matched and compatible results of wide-rib specimen testing at the speed of 25 mm/min (reference method), where the variance value of these two methods is not significant.