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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.

Sensors for detecting various gases, such as nitrogen oxides, play a major role in times of climate change in protecting the environment from the possible toxic influences of such gases. Due to their usually complex design, gas sensors may react to changes in the operating temperature, which can occur due to different ambient influences. This article shows two methods for accurately measuring the temperature on the surface of a sensor under realistic conditions.

Continuous inspection of gases is increasingly important for process monitoring, like fruit ripening. This involves the detection of individual markers in complex gas mixtures, e.g., to indicate spoilage. Unfortunately, classical techniques are lab-bound and resource-intensive. Hence, small, low-cost systems are being developed. Thereto, we propose a sensor system, containing a non-heated gas separation unit and gas sensors combined with a compensation of surrounding temperature effects.

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.

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.

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 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.

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.

Because most commercialized current sensors can only measure current flow when a signal line is inserted into a clamp-shaped probe, it is impossible to measure the current waveform of a high-end PCB with a sub-millimeter fine pitch. We developed a pin-type current probe with high sensitivity, targeting the analysis of high-end PCBs. The probe can measure the current waveform by simply contacting the measurement point. This paper reports on the current sensor development.

We have managed to reduce the measuring time of previously common hydrogel-based sensors from a few minutes to a few seconds. For this, the arrangement of the hydrogel in the sensor was changed so that the volume of the hydrogel could be reduced. The biggest challenge, apart from generating a very thin pattern, was to firmly bond the hydrogel to a silicon surface. This was to ensure that the resulting forces of the bimorph effect can be absorbed.

A new method for water detection in lubricated rail components is presented. It is based on a robust humidity sensor combined with robust data evaluation to determine the water content of greases. Based on a laboratory evaluation in the relevant environment, the presented approach offers an online monitoring tool to predict the water content of grease-lubricated rail parts, thereby enhancing the reliability and safety while reducing the maintenance costs and downtime of railway wagons.

Many applications which measure physical quantities rely on wireless surface acoustic wave sensors. The accuracy of this sensor depends directly on the measurement of its main frequency. This paper aims to compare three methods for this measurement in one shot: fast Fourier transform, discrete wavelet transform, and empirical mode decomposition. Results show that the choice of the method is conditioned by the disturbance level and that the wavelet method is the best way for harsh environments.

After an earthquake, many resources are spent to evaluate the level of damage suffered by buildings and infrastructure. To improve the efficiency and reduce the subjectivity of such assessments, a robotic total station (RTS) can be a useful support. This work aims evaluates the performance of a RTS for use in emergency conditions. Furthermore, the analysis of reduced configurations of the monitoring points highlights interesting aspects for defining a standardized, simplified procedure.

Phase-measuring deflectometry is an optical shape measurement technique for reflective surfaces. The basic idea is that a pattern that is observed through reflection on a curved surface gets distorted and reveals information about its shape. In this work we describe a method to move the pattern to obtain data for quantitative shape determination. The experimental setup is calibrated. With a laser tracker we reveal calibration errors and discuss their influence on the reconstructed shape.

This article describes a method to measure the parameters of piezoelectric materials. This is done by evaluating the complex electrical resistance of a sample. However, the properties of the material can not be calculated directly from the electrical resistance. Instead, a simulation model of the sample is created, and the parameters of the simulation model are adapted using an optimisation algorithm until the model's resistance and the resistance of the physical sample match.

This study concerns development and evaluation of a high-temperature-resilient ammonia sensor tailored for ammonia slip monitoring to improve NO_x and NH₃ emission reduction from coal-fuelled, biomass-fuelled, heat and power plants. In particular, by tuning the gas-sensitive materials' nanostructure, the interference from carbon monoxide in the ammonia measurement could be markedly reduced, thus allowing more accurate ammonia monitoring in the flue gas from a real combined heat and power plant.

There is a need to develop an unambiguous digital version of the International System of Units (SI), as required for information systems and distributed sensor networks. The unit kilogram could already replace the non-SI unit for atomic masses (dalton, Da) because the experimental uncertainties are now very close. But changing the current status of the well-known unit decibel would require considerably more time, until a digital version of a Unique SI Reference Point would be approved.

We present a concept for angle and position measurement based on metamaterials. The distance between the sensor and the rotating or moving metamaterial target is not limited to a precise value. We use state-of-the-art millimeter wave radar chip technology for read-out, initially intended for applications such as gesture recognition or contactless switches. We implement a demonstrator test setup and show the proof of principle.

Greenhouse gas emissions from freshwaters are not well quantified on a global scale. Our prototype monitors aqueous concentrations of CH₄ and CO₂ at relevant timescales. Our low-cost design allows the application of replicated sensors to capture spatial heterogeneity and temporal variability in dissolved gases in highly dynamic ecosystems, thereby addressing a major bottleneck in the reliable estimation of emissions. We provide a detailed prototype description and share software code.

Our research introduces an innovative method to improve the quality control of plastic granules, crucial in industries like manufacturing and automotive. We addressed a common issue: identifying "burn marks" on granules caused by overheating during processing. By combining advanced machine learning and a novel data augmentation technique called "cutout", we significantly enhanced the detection accuracy of these defects.