Measurements are nowadays permanent attendants of scientific research, health, medical care and treatment, industrial development, safety and even global economy. All of them depend on accurate measurements and tests, and many of these fields are under the legal metrology because of their severity. How the measurement is accurate, is expressed by uncertainty, which is obtained by multiplication of standard deviations by coverage factors to increase trustfulness in the measured results. These coverage factors depend on degree of freedom, which is the function of the number of implied repetitions of measurements, and therefore the reliability of the results is increased. The standard coverage factor is 1.96 for normal (Gaussian) distributions or near-Gaussian distributions, and the obtained expanded uncertainty has the 95% statistical probability. In general, it is not possible to achieve the 95% confidence interval by using the standard coverage factor 1.96, nevertheless of the degree of freedom. The present paper describes the method of estimating the expanded uncertainty by an algorithm of this model based on the 95% confidence interval of any probability distribution of any shape, dealing with the A-type or the B-type uncertainty. Furthermore the coverage factor is determined due to the 95% confidence interval of the actual probability distribution. The algorithm successfully copes with adding two or more uncertainties with mathematical properties of sums, and is established in accordance with the standards and guides. The model is introduced in procedures carried out in the calibration laboratory.

Technical requirements and economical impacts of flow measurements in sewer systems are a issue concern in today's system's management. Thus, the quality of the measurements is considered to be a critical issue. Considering the complex nature of the measurand and the metrological requirements of local installations, the best available level of accuracy in measurement results should be sought. Therefore, both the knowledge of the measurand estimates and measurement of uncertainties are required for achieving robust results.
Within this context, the quality of measurement results depends on the knowledge of the uncertainty contributions and on the selection of an appropriate method to evaluate the measurement uncertainty. The study of these aspects can be of major importance in providing information to management of the system, namely in the selection of appropriate technology, upgrading and maintenance activities.
The Monte Carlo method is used in this paper to carry out the evaluation of the measurement uncertainty, considering its inherent capacity to deal with non-linear and multi-stage mathematical models. Influence of geometric conditions and other relevant parameters in the quality of measurements is discussed. The study was developed within the context of a specific sewer system, using a particular measurement system, from which measurement data was gathered.

The accurate measurement of many power quality parameters using digital sampling techniques relies on synchronisation between the sampling system and the signal under analysis. If synchronisation is not available measurement errors result due to the difference in frequency of the digitised signal and that expected and based on the sampling clock of the measurement system.
A method is presented of correcting for this lack of synchronisation. This method relies on a time domain interpolation technique to modify the sampling rate of the captured signal in software. In order to find the correct sampling rate a scanning technique is used which requires some method of assessing the lack of synchronisation and associated error in the analysis of the signal. A number of methods of achieving this are presented and compared. The suitability of the algorithm for power quality measurements under noisy conditions is assessed.

This paper describes the new method of time-interval-error (TIE) estimation and prediction. This method is very useful for standard clocks characterization and can be applied in high precision measurement and telecommunication systems with high resolution of the time-base. TIE can be easily and fast calculated using only two parameters obtained during calibration process. Moreover, it is very simple method for clocks comparison and can be applied in time-interval measuring systems (TIMS) for calibration or TIE calculation. This method allows to calculate an accumulated jitter and TIE as a function of the clock cycles. The measurement system, specially accommodated for jitter measurements and their application for estimations or predictions of jitter parameters will be also presented and discussed.

Radiation sealed sources have an emission that could be studied by theirs isodose surfaces. The intersection of a plan with such a surfaces is described by the dose rate contour curves. It is very common to assume that these surfaces have rotational symmetry around the longitudinal axis, and so, the contour curves have mirror symmetries. Here it is shown, by a computational simulation, that if the radioactive material inside de sealed vessel is not homogeneous, the uncertainty in dose rate measurements could achieve high values. This uncertainty value is exemplified in a iodine-125 seed source used for brachytherapy purposes.