Special issue  

In this work, a novel approach to deduce the release of the natural radioactive noble gas ²²²Rn from solid sources containing the isotope ²²⁶Ra is presented. Therein, supporting radioactivity measurements of the source are used in conjunction with a theoretical description of the dynamics. For radiation protection and environmental research, reliable and comparable ²²²Rn measurements, and therefore reference atmospheres of ²²²Rn, are needed. This work improves their realization.

This work deals with process monitoring. In particular, the process of used-sand regeneration is monitored with the aid of impedance spectroscopy and can be controlled in the future with the measurement data obtained in this way. This results in the following aspects: a consistently high quality of the process material is realized by a controlled process. At the same time, energy consumption is minimized. The result is a process that is both more resource-efficient and more economical.

We pursue a promising novel self-adaptive spiking neural analog-to-digital data conversion (SN-ADC) design that uses spike time to carry information. Thus, SN-ADC can be effectively translated to aggressive new technologies to implement reliable advanced sensory electronic systems. The SN-ADC supports self-x (self-calibration, self-optimization, and self-healing) and machine learning required for the internet of things and Industry 4.0 and is based on a self-adaptive CMOS memristor.

Industrial X-ray computed tomography is a holistic measurement technique for dimensional metrology. However, the relatively long measurement time is a hindrance to its application. A possibility to reduce measurement times, the continuous scan mode, is characterized in this work. The question is how much the time reduction impacts the accuracy of the dimensional measurements. The core result of the paper is an estimate of the effect along with experimental proof that this estimate is reasonable.

The measurement principle shows how to measure calibration torque moment shunts in a 5 MN m torque standard machine using an interferometer and hinge flexure stiffness. The analysis of the measurement uncertainty influences shows that the measurement uncertainty of transversal force measurement ranges from 0.61 % to 3.04 % and stays constant at 1.7 % for torque measurement. A FE validation was performed. The measurement uncertainty of the calibration torque moment sank from 0.106 % to 0.100 %.

Gas analysis by absorption spectroscopy helps to optimize combustion processes in engines. Optical distance sensors are non-contact and offer high accuracy and precision. Both sensor applications benefit from light sources with a rapidly swept wavelength to monitor dynamic processes. In our paper, we precisely characterize the dynamic wavelength sweep of a rapidly pulsed VCSEL (vertical cavity surface emitting laser), a tiny semiconductor laser well suited for optical sensing.

Modern production concepts generate a demand for reliable, energy-efficient, fast, and secure wireless communication solutions. Therefore, the current consumption should not increase substantially due to additional security operations. This paper shows a principle current measurement method that is exemplary of a transceiver for IO-Link Wireless protocol. The results show that the current consumption only increases slightly with acceptable measurement uncertainty.

In this contribution the frequency domain fluorescence lifetime imaging microscopy (FD-FLIM) technique is evaluated for post-consumer wood sorting. The measured data were processed using algorithmic decision trees to identify the wood species and post-consumer wood category. The experimental results revealed the high potential of the FD-FLIM technique for automated post-consumer wood sorting.

The present research work investigated the acoustic manipulation of bioparticles and cells in closed and liquid-filled vessels using a special method for focusing acoustic fields. Based on simulation studies, the feasibility of particle manipulation with this method was successfully demonstrated. Successful final testing using a demonstrator and thus the transfer and prospective application in biotechnology are part of further research work.

An adjustment concept for high-precision weighing cells has been developed and experimentally investigated. It allows for minimization of uncertainty contributions due to tilt while maximizing sensitivity to mass. By applying the adjustment capabilities to new weighing cells, the devices can simultaneously become more accurate, more adaptable and more robust.

It is a great challenge to apply a diagnostic system to engine test beds. The main problem is that such test beds involve frequent configuration changes. Therefore, the diagnostic system must be highly adaptable. A modular toolbox-based approach combines physics-based and data-driven modeling concepts and, thus, enables highly flexible application. Adaptability and detection quality are validated using measurement data from a single-cylinder engine and a multicylinder engine.

The paper proposes a structure for the creation of new simulation software for uncertainty estimation. The structure was derived from the well-established VCMM. To make it easy to apply the software structure to specific projects, a supporting software library (written in C++) was created. The library provides all the components necessary to create software for uncertainty estimation. The software structure and library proposed can be used in different domains of metrology.

The method of non-contact temperature measurement in conjunction with a 3D sensor described in this paper can be used to determine the heat loss of technical devices and industrial plants. This measurement tool thus helps to optimize the energy efficiency of these devices and plants.

Bees play a major role in our ecosystem and the human food supply chain. Numerous threats, from pesticides to parasites, endanger bees and possibly cause bee colony collapse. The Varroa mite is one major parasite, and its timely detection and treatment is a key task for beekeepers. Contemporary sensors, electronics, and AI/PR allow vital parameters of bee hives to be monitored. Recent gas sensors (e.g., SGP30 or BME680) allow continuous in-hive parameter and Varroa population monitoring.

A setup for the characterization of liquids with the perspective of monitoring crystallization processes is presented. The novelty of this setup is the realization of viscosity and conductivity measurements using two quartz crystal microbalances. Additionally, there is the possibility to apply an electric field through the sample, enabling the manipulation of charged particles. The results show that the measured values are in reasonable agreement with values from the literature or standards.

We investigated the feasibility of indium tin oxide (ITO) as an alternative plasmonic material to replace noble metals for sensing applications in the mid-infrared region. An ITO-based plasmonic slot waveguide was numerically designed and analysed for a wavelength of 4.26 µm, which is the absorption band of CO₂. As the proposed structure shows low propagation lengths, we concluded that ITO appears not to be an appropriate candidate for plasmonic waveguiding systems.

Temperature sensors based on piezoelectric devices enable precise measurement of temperature changes in harsh environments such as high temperatures or aggressive atmospheres. In the case of this device, the change in the temperature is detected by means of the changing resonance frequency of the sensor. Here a sensor device based on catangasite (an isomorph of quartz) is presented. We discuss its behavior at elevated temperatures and confirm that it can successfully operate up to 1030 °C.