Special issue  

Temperature measurements are of great importance for the control of processes, for quality assurance, and for plant safety. It is not always possible to measure temperatures directly in the medium but on the surface of vessels and pipelines, etc. However, when determining the surface temperature with contact thermometers, a number of influencing variables, some of which are difficult to determine, affect accurate and reproducible temperature measurement. These are presented in the article.

In this work, the determination of the degree of cross-linking was investigated using absolute optical measurements with an integrating sphere and Raman spectroscopy. PE-Xc, on the basis of HDPE and UHMWPE and various thermosets, was examined. Laboratory methods (e.g. wet chemical analysis, DSC, and DEA) were used for comparison. A good correlation of the results of the optical methods with those of the laboratory methods could be shown and serves as a basis for further investigations.

In order to save time and avoid overheating of food during unfreezing, the study of ice content can be very useful. The aim of the research is to design an ultrasound-based sensor system that is able to comment on the content of ice in the sample food product. Some sample food products are tested, and the observations and challenges concerning the same are mentioned in the research paper.

Infrared spectroscopy is great for determining the composition of liquids. Combined with attenuated total reflection (ATR), one can just put the sample on the sensitive surface. We made a compact device with a diamond-coated silicon ATR crystal to protect the surface against aggressive fluids. Silicon crystal, light source and detector are hermetically sealed in a housing. Our tests show that the diamond coating enhanced the sensitivity compared to uncoated ATR elements as predicted by theory.

Mathematical models are often required to process sensor data in a digital twin platform. The translation of models to an updateable format enables predicting hidden states of the physical object, which are not directly measurable. The linking of different models is demonstrated by data from field tests on fruit transportation in refrigerated containers. We programmed a streaming platform that enables easy integration of such updatable models with only a few milliseconds of processing overhead.

In this work, we investigated whether artificial feedback in the form of vibration has an effect on the accuracy and precision of eye tracking glasses. The results enabled the development of design proposals for vibrotactile feedback in gaze-based control systems for robotic arms.

In this work, we have developed and validated a semi-automatic approach that greatly reduces the amount of interaction and effort needed for analyzing samples via gas chromatography–mass spectrometry. Further, unlike many other approaches, our developed tool is accessible to the novice and does not require any programming experience. Using whisky as an example substance, we show how the analysis method compares to conventional software, and we validate our approach against that.

The paper describes a novel energy-harvesting system based on the Wiegand effect. The energy provided by this harvester is analysed and correlated to the required energy to start a microcontroller and perform some wireless data transfer. The energy consumption is analysed in detail down to component level. A demonstrator including an additional sensor and wireless transmitter was built, proving that sufficient energy is provided by the harvester for the wireless transfer of the sensor data.

We present a photoacoustic sensor enabling fast, inexpensive, and highly sensitive methane detection in environmental monitoring applications. Six different T-cell designs were both theoretically and experimentally investigated. The aim was to understand the photoacoustic signal generation and resonances in relation to the different cell geometries, and determine the long-term stability and the detection limits for methane. These were below the methane background concentration in air of 1.8 ppm.

Differential scanning calorimetry (DSC) is a widely used tool to analyze thermal material properties. This study focuses on the advancement of a miniaturized DSC chip as an alternative to conventional devices. The first development steps for the integration of a weighing system are shown, starting with model considerations and simulation-based optimization to initial measurements. Three different measurement methods are investigated and show promising results.