Calibration procedures are widely implemented in metrology. This paper considers the evaluation of measurement uncertainty associated with the use of a calibration function. Three methods for uncertainty evaluation are described and the differences in the results returned are discussed. A simple calibration function is used to illustrate these differences.

The four-point probe method, elaborated by van der Pauw, can be applied also in absolute measurements of electrical conductivity of electrolyte solutions. Conductance cells designed and used according to the method have their cell constant dependent on a single geometrical dimension only – the height. One of such designs, with electrodes located in chambers separated from the measuring space of the cell by narrow gaps, has especially advantageous properties as a calculable cell. This was presented in the previous works of the main author of this paper. The analysis performed there indicates that the consistency between theoretical and experimental results is limited by non-ideal properties of applied instrumentation rather than by the principle of the method. This paper presents later experimental examinations of the cell, carried out in the measuring arrangement improved on the basis of the conclusions presented in the former works. Absolute determinations of electrolytic conductivity of 0.01 and 0.1 kmol/m³ NaCl solutions were performed. The results obtained confirm the hypothesis that the cell constant of such a cell can be determined from its height with uncertainty of the order of a few hundredths percent.

During the past decades, Ocean Bottom Seismometers (OBS) have played a key role in permanent seismic activity monitoring at sea as well as allowing a better understating of the earth interior. Data collected by the instrument can provide information on the ocean bottom sub-layers down to a depth of 40 km beneath the ocean floor. The accuracy of the results directly depends on the time drift of the equipment due to change of environmental conditions. Time base of the OBS is given by a unique stable crystal oscillator.
This paper presents the time drift study of an Ocean Bottom Seismometer in real environmental conditions. By means of a climate chamber, temperature and humidity tests of a general purpose time base generator were carried out and crystal temperature stability and time drift were calculated. Furthermore, the behaviour of the time drift of the instrument has been evaluated in order to correct the data in the data processing stage.

In this paper a new non-destructive testing (NDT) system focusing on micro size superficial defects in metals is presented. The innovative system is composed by a new type of eddy currents probe, electronic devices for signal generation, conditioning and conversion, automated mechanized scanning and analysis software. The key original aspect of this system is the new type of eddy currents probe. This new IOnic probe provides enhanced lift-off immunity and improved sensitivity for micro size imperfections. The probe concept was studied using a Finite Element Modeling (FEM) tool and experimental verified using a standard defect.
The testing results on some Friction Stir Welding (FSW) specimens clearly show that the system is able to detect cracks about 50 µm depth, which significantly increases the actual state of the art in NDT reliability for micro imperfections detection. The system can be applied to a broad range of industries which include manufacturing, maintenance and engineering companies.

This paper describes the Metrovisionlab computer application implemented as a toolbox for the Matlab program. It is designed for learning the key aspects of camera calibration techniques in dimensional metrology applications such as laser triangulation sensors and photogrammetry or stereovision systems. The software is used in several industrial vision courses for senior undergraduate mechanical engineering students. The application:
1) simulates a virtual camera, providing a simple and visual understanding of how the various characteristics of a camera influence the image that it captures;
2) generates the coordinates of synthetic calibration points, both in the world reference system and the image reference system, commonly used in camera calibration; and
3) can calibrate with the most important and widely-used methods in the area of vision cameras, using coplanar (2D) or non-coplanar (3D) calibration points. Thus, the main goal is to have a simulation tool that allows characterizing the accuracy, repeatability, error mechanisms and influences for different measurement conditions and camera calibration algorithms.