Abstracted/indexed

Effective from 20 May 2019, the kilogram is now defined in terms of the numerical value of the Planck constant h. Replacing the artefact definition of the kilogram by a new one based on the mass of a particle, or the atomic mass constant m_u, would have been preferable for ease of understanding, among other reasons. In this paper we will discuss some educational limitations of teaching to different audiences the new definition and corresponding realizations of the kilogram.

We present the metrological characterization and calibration of three different types of thermographic cameras for quantitative temperature measurement traceable to the International Temperature Scale (ITS-90). Relevant technical specifications are determined according to the requirements given in the series of Technical Directives VDI/VDE 5585. For the IETD and the NU, we also show how a significant improvement in the parameters can be achieved with the help of the data reference method.

Applications like air quality, fire detection and detection of explosives require selective and quantitative measurements in an ever-changing background of interfering gases. One main issue hindering the successful implementation of gas sensors in real-world applications is the lack of appropriate calibration procedures for advanced gas sensor systems. This article presents a calibration scheme for gas sensors based on gas profiles with unique randomized gas mixtures.

Traceably calibrated scanning Hall microscopy (SHM) is a versatile tool for the quantitative characterization of magnetic microstructures. To enable SHM with a resolution in the micrometer range under ambient conditions, two Hall sensor materials, gold and graphene, were investigated. A SHM setup utilizing a 5 μm gold Hall sensor was calibrated. The field sensitivity and the detailed uncertainty budget are discussed. The presented traceable calibration is validated by comparison to simulations.

The new concept of a unified pH scale can be used to compare acidities of different kinds of solvents and their mixtures. The aim of the work was to investigate the robustness of the measurement method with four commercially available glass electrodes for non-aqueous media in comparison with the rather specific type of cell used so far for this measurement. The measurement results in aqueous mixtures of ethanol show good agreement.

The necessity to measure harmonic emissions between 2 and 150 kHz is outlined by several standard committees and electrical utilities. This paper presents a measurement system and its traceable characterization designed to acquire and analyze voltages up to 230 V and currents up to 100 A with harmonics up to 150 kHz that may occur in smart grids. The uncertainty estimation is carried out and described in detail for both the fundamental and suprahmarmonics components.

In order to further increase the performance of neural networks in the field of optical quality assurance of soldered joints, a hierarchical classifier can be used instead of a single network. The global expansion of the classifier enables the inspection task to be distributed over several subnetworks, which results in higher accuracy. Since the individual sub-models only concentrate on the identification of certain characteristics, categorical problems can be solved more effectively.

A commercial solid electrolyte gas sensor of the type "Pt|YSZ|Pt, air" based on yttria-stabilized zirconia for colorimetric oxygen detection was operated in optimized dynamic electrochemical modes. Cyclic voltammetry and square-wave voltammetry were used for the detection of NO and O₂ in N₂ in the temperature range between 550 and 750 °C. Due to the differences of electrode kinetics of the single components it is possible to detect these redox active gases selectively and quasi-simultaneously.