Standard bullets and casings are currently under development to support the National Integrated Ballistics Information Network (NIBIN) in the U.S. Based on a numerically controlled diamond turning technique, 20 RM 8240 standard bullets were fabricated in 2002. Test results show high repeatability and reproducibility for the bullet signatures on these RM bullets. Prototype standard casings were also manufactured using an electro-forming technique, and are currently under test. These RM bullets and casings are intended for measurement traceability and quality control for ballistics...
The knowledge of metrological history of pressure standards is of a big importance for determination of their metrological capabilities. When providing traceability to lower metrological levels it is essential to determine the uncertainty of generated reference pressure. The estimation of the uncertainty of generated reference pressure can be done only by analysing metrological history of selected standard and estimation of all parameters that have the influence on the generated reference pressure uncertainty. Analyses of selected LMPS (Laboratory of Measurements in Process Engineering)...
Methods enabling a determination of errors eI and dI for a high transformation ratio difference between a standard and tested instrument current transformers (ICT) are described in this article. A widespread method uses an automatic transformer test set for the measurement of a difference between a standard and tested ICT. A method transforming secondary currents to voltages and an indirect method using error measurement from magnetizing current are also described.
The modelling of the measurement is a key element of the evaluation of measurement uncertainty in accordance with the basic concept of the Guide to the Expression of Uncertainty in Measurement (GUM). The model equation expresses the relationship between the measurand and all relevant input quantities contributing to the measurement result. It serves as a basis for propagation of the probability density distributions for the input quantities or, in case of (almost) linear systems, for Gaussian propagation of the related standard uncertainty contributions. A practical and highly versatile...
A measurement process represents a controlled learning process in which various aspects on uncertainty analysis are investigated. A measurement process is performed if information supplied by it is likely to be considerably more accurate, stable and reliable than the pool of information already available. The substantial amount of information, got with respect to the conditions prior to the result after the measurement process is performed, can be connected to the "Kullback's principle of minimum cross-entropy". This, as it is known, is a correct method of inductive inference when no...
The evaluation of key comparison data is discussed, the general case of correlated data being considered. Particular attention is paid to a simplified procedure for data evaluation, founded on a mixture of distributions associated with the results from the institutes participating in the comparison. The suggested approach uses the model of an interlaboratory experiment from ISO 5725 and uncertainty evaluation in accordance with the Guide to the Expression of Uncertainty in Measurement.
In this work are analysed performance of quality assurance in the Estonian measuring instruments verification laboratories. During last 10 years had Estonia changed completely and this involves also activity on the metrology area. Basic change was case, that on the previous period the verification was mandatory for almost all measuring instruments, now shall it be replaced greatly by voluntary calibration. But verification stays highly required service. Verification area involves mainly measuring instruments which are used in affairs. New is also fact that now-a-days verification...
This work investigates the determination of measurement uncertainty in calibration of small angle measurement instruments. After attentive study of the sources of variation, an expression was developed to determine the measurement uncertainty. Two approaches were used to determine the measurement uncertainty: ISO GUM and Monte Carlo simulation method. An example is presented and the calibration of an Electronic level was carried out using a sine table at the Metrology Laboratory, in the University of Brasília, Brazil. The expanded uncertainty results showed good agreement of both techniques...
In our recent papers we have dealt with the assessment of the uncertainties associated with the virtual instrument measurements, proposing two completely different methods. The first one is based on an original application of the "uncertainty propagation law" of the ISO "Guide to the expression of uncertainty in measurement". The second one is a numerical approach, based on the Monte Carlo simulation. In this paper we show how the proposed approaches can be implemented in the virtual instruments in order to make the instrument itself able to auto-estimate the measurement uncertainties.
With an intention to reveal possible inaccuracies of mathematical models used in calculations of frequency characteristics of resistors of octofilar design, comparisons of a 12 906 Ω and a 1 Ω octofilar resistor against monofilar and quadrifilar calculable resistors of the same nominal values have been performed. A possibility to carry out these precision comparisons by means of a commercially available LCR meter has been investigated.