The paper is devoted to some problems related to the development of an international vocabulary of terms in metrology. Using terms from Section 3 of VIM, it is shown that in many cases, on one hand, the same terms are interpreted in a different way; but on the other hand, different terms are used to express the same ideas. The origins of ambiguity are analyzed. Proposals which could contribute to softening the problems of terminology development are given.

The paper reviews the background of the primary calibration of acoustic emission (AE) sensors and the determination of uncertainty in the calibration. The main sources of uncertainty in practical usage of calibration results are discussed. The comparison of the results of the reciprocity primary calibration, step-force and reciprocity calibration with broadband-pulse excitation method is presented. The shape of calibration characteristics corresponds well up to 300 kHz. The calculation of the uncertainty in all the calibration methods is described. The problem of propagation of uncertainty in the fast Fourier algorithm was solved. Uncertainty of measurement by primary calibration is determined and the influence of selected sources of uncertainty for each used method of calibration is presented and practically measured results are discussed. Piezoelectric AE sensor PAC UT1000 was used as the sensor under test. The big influence on uncertainty in calibrations was the influence of remounting sensors and influence of precision of measuring device. This influence is possible to suppress by correct and precise mounting of the sensors and using of more accurate measuring device with high resolution.

This paper presents the implementation of a measurement uncertainty assessment guideline applicable to laboratory assessors. Measurement uncertainty is a relevant subject for all laboratories as well as for accreditation bodies since it consists in an elementary requirement for ISO/IEC 17025 accreditation. Therefore, it is crucial to assure that all technical assessors have an adequate level of knowledge about measurement uncertainty and know how to proper assess it. Researching the literature, it is possible to observe that all measurement uncertainty guidelines are focused on the laboratory perspective, to help them implement GUM's concepts. This work, on the other hand, was focused on the implementation of a new measurement uncertainty guideline intended exclusively to help laboratory assessors improve their knowledge about this subject and better prepare them to carry out laboratory assessments. The guideline was implemented in Rede Metrológica RS (RMRS), a regional accreditation body from southern Brazil. Simultaneously to this measurement uncertainty assessment guideline, it was also prepared a measurement uncertainty check-list to help assessors conduct their laboratory assessments. As a result, an improvement on the level of knowledge about measurement uncertainty was observed among RMRS assessors. The improvement was possible to verify through the application of written exams about measurement uncertainty, before and after the training on the new guideline. Exams showed the improvement of assessors' knowledge, demonstrating the relevance of this innovative work.

In this article we introduce the results of density and volume measurements of sub-gram and 1 kg weighs. At first the theoretical principles of such experiments are described. These include the uncertainty calculations. Sub-gram weights were measured in volume and mass comparators. The results are shown in the last part of this paper. The result is, that our primary mass laboratory can measure the density of milligram weight with uncertainty below 2000 kg/m³ (k = 2).

Many studies have been developed aiming to improve digital filters realizations, recurring to intricate structures and analysing the error´s behaviour. The work presented in this paper analyses the feasibility of fixed-point implementation of classical IIR notch filters (Butterworth, Chebyshev, Bessel and elliptic), and also the effect of the quality factor and normalized cut-off frequency in the number of significant bits necessary to represent the coefficients, to scrutinize the deformations the filters suffer for distinct design specifications.
The work focuses especially in the implementation of power line notch filters used to improve the signal-to-noise ratio in biomedical signals. The obtained results, when quantizing the digital notch filters, show that by applying second order sections decomposition, low-order digital filters may be designed using only part of double precision capabilities, while high-order notch filters with harsh design constrains are implementable using double precision, but only in second-order sections. Thus, it is shown that to optimize computation time in real-time applications, an optimal digital notch filter implementation platform should have variable arithmetic precision.