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For safety, environmental and economic reasons, methane leak detection is one of the most requested tasks for gas measurement devices. This paper compares the performance of a laser-based optical and acoustical detection scheme at different wavelengths and laser types, respectively. This forms a good basis for further developments of methane leak detection devices or can help to choose the right configuration for a certain methane leak detection application.

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.

The estimation of the six-degree-of-freedom position and orientation of an end effector is of high interest in industrial robotics. High precision and data rates are important requirements when choosing an adequate measurement system. In this work, a six-degree-of-freedom pose estimation setup based on laser multilateration is described together with the measurement principle and self-calibration strategies used in this setup. In an experimental setup, data rates of 200 Hz are achieved.

This paper deals with the electrical investigation of various sand mixtures used in foundries for mold and core production. It is possible to classify various molding sand mixtures reproducibly on the basis of their electrical characteristics. This knowledge can now be used to develop measurement systems for processes in the foundry industry and thus increase product quality. In addition, resources can be conserved, and functioning closed-loop systems can be integrated into foundry processes.

This paper discusses the deployment of an internet of things (IoT)-based model to monitor the fermentation of tea in a tea factory in Kenya. The model uses deep learning to detect the optimum fermentation of tea as fermentation progresses. To further improve on the results, a majority voting technique based on regions is used. The model shows promising results, and its predictions correlated well with those of the experts.

A novel, low-cost measurement device for simultaneous high temperature measurements of the electrical conductivity and Hall coefficient has been developed. Simulations were used to design a suitable screen-printed planar platinum heating structure that generates temperatures of up to 600 °C. Simulations of the temperature distribution have been validated using thermal imaging. Measurements were compared with data from the literature to validate the functionality of the novel device.

Synchronization problems within distributed sensor networks are a major challenge in the field of Industry 4.0. In this paper, artificially generated time shifts between sensor data and their influence on remaining useful lifetime prediction of electromechanical cylinders are investigated. It is shown that time shifts within sensor data lead to poor remaining useful lifetime predictions. However, this prediction can be significantly improved using various methods as shown in this contribution.

Ion-selective electrodes have been proven useful in water analysis. They are usually used as single-rod measuring chains in different designs, which are manufactured using precision mechanical manufacturing and assembling technologies. The paper describes a microsystem technology approach for the fabrication of miniaturized electrochemical sensors. Design, manufacture, and performance of the novel ceramic multilayer-based sensor array are presented in the paper using various examples.

The Physikalisch-Technische Bundesanstalt has set up a primary method for the calibration of the spectral responsivity of thermal detectors in the near- and mid-infrared spectral range. This method uses the calculable radiation of a blackbody radiator and optical bandpass filters. The obtained results with relative standard measurement uncertainties between 5 % and 19 % are consistent with previous calibrations at PTB's national primary detector standard and extend the usable wavelength range.

Virtual assembly (VA) is a method for the quality prediction of assemblies considering local form deviations of relevant geometries. Point clouds of measured objects are registered in order to recreate the objects’ hypothetical physical assembly state, which is strongly influenced by the measurement uncertainty of individual points. Thus, we studied the propagation of uncertainties by VA. The results reveal larger propagated uncertainties by VA compared to the unconstrained Gaussian best fit.

NiCr-carbon thin-film strain gauges offer the outstanding characteristic of a very high strain sensitivity. This can be very advantageous for many high-precision mechanical sensors like load cells. A downside of sensors based on these NiCr-carbon strain gauges is a rather large creep error, meaning reversible signal deviations at a constant load. We present two applicable methods for adjustment of the creep error: a modification of the film composition and a modification of the strain transfer.

The actuators of precise positioning based on LiNbO₃ or LiTaO₃ bimorph structures are considered. They consist of two joined plates: one of them lengthens and the other one shortens under the influence of an electric field and, as a result, the actuator bends. Such a device ensures small movements of probes in scanning probe microscopes, micro-electromechanical systems, micro-motors, etc. We determine the optimal orientations of the plates, ensuring the highest possible actuator displacements.

The selective catalytic reduction, an after-treatment method using diesel exhaust fluid (AdBlue), is needed to reduce the emissions of diesel combustion processes. It is crucial to monitor the diesel exhaust fluid. This article presents a platinum thin-film sensor using the 3-omega method to characterize the diesel exhaust fluid. The information about the concentration of urea in water can be extracted. The results show that this sensor can determine the urea content to within 1 % by weight.

During the geometric calibration of infrared cameras, the parameters that describe where object points are mapped onto thermal images are determined. The required reference data is obtained by capturing so-called calibration targets. In established approaches, it is difficult to estimate the lens distortions precisely. A newly developed target and its evaluation algorithm make it possible to increase the sensitivity of the calibration by finding reference points close to image borders.

We have prepared an article that demonstrates one of the ways to recognize objects on the ground surface. This paper is a result of experimental data that were collected with unnamed aerial vehicles (UAVs) with synthetic aperture radar. Although UAV radar has a small monitoring area, we noted that such pictures can contain the steady features of the mutual arrangement between detected objects. We have constructed an artificial neural network that solves the tasks of group object recognition.

Detection of flammable gases is necessary to avoid explosive atmospheres. Commercial pellistors require an operation temperature above 450 °C for the detection of methane. We present a novel wireless low-power catalytic gas sensor system based on non-precious metal catalyst for the detection of methane and propane operated at 350 °C. The combination of a MEMS-based sensor with a low-power radio system provides the opportunity to monitor complex infrastructures without using a power grid.

We propose a surface plasmon resonance (SPR) sensor based on a ZnO / Au hybrid thin-film material structure and experimentally investigate its sensitivity improvement. The Kretschmann-based SPR sensor utilizes ZnO thin films and nanostructures for performance enhancement. The advancement in SPR technology relies on a low-cost, high-sensitivity, and high-selectivity sensor. Metal oxide (MO) has been incorporated into the SPR sensor to be used for detection of biological and chemical compounds.

The publication contributes to a uniform procedure for in-process measurement data acquisition in additive manufacturing, which is essential for a controlled correction of detected manufacturing deviations. The developed methodology is based on an analysis of the melt pool contours relative to a referencing system integrated in the powder bed. By recording the referenced melt pool and the shimmering contours after powder application, manufacturing deviations can be evaluated more accurately.

A TIR100-2 emissometer is used to measure the emissivity of thermal insulation products using the low-emissivity effect to increase the thermal resistance, but the uncertainties of measurements on low-emissivity foils were not known. The study allowed the determination of the uncertainty through the detailed analysis of the measurement principle and the determination of the influences of the parameters. The measurement results were validated by comparison to a reference measurement setup.

The dose rate and spectral distribution of X-ray emissions from laser materials processing have been determined using a thermoluminescence detector (TLD)-based spectrometer. The penetration depth of the radiation into the spectrometer depends on its energy, so that the energy-resolved spectrum of the radiation can be calculated from the TLD dose values by means of mathematical methods (Bayesian deconvolution). The measurements are traceable to the SI.

Differential thermal analysis (DTA) was used to examine the effect of the particle size and morphology of Co₃O₄ on its thermal response under exposure to 1 % CH₄. The DTA response results from the catalytic oxidation of methane. Co₃O₄ samples differing in particle size and morphology were produced by ball milling or were synthesized. The investigations performed with temperatures between 250 and 450 °C reveal that both particle size and shape have a considerable effect on thermal response.

A novel experience replay particle swarm optimization algorithm is presented and successfully deployed to improve the optimization performance for reconfigurable analog integrated circuits of industry 4.0. An optimization approach is introduced that relied on THD-based indirect measurement method that varies from the traditional calibration approach. Instead, the proposed calibration methodology optimizes all characteristics of the reconfigurable amplifier at once.

In thermometry, the displayed temperature value of an object depends on the size of the object. This behaviour, the size-of-source effect, might be a major cause of measurement uncertainty in a thermoscene. The influence of diffraction and digitization can be described advantageously with the modulation transfer function. Especially with very small objects the displayed temperatures are too low. When imaging large objects, not only the edge areas are affected, but also the entire image.

In order to contribute to a standardisation and process monitoring of additive manufacturing (AM) processes, a novel referencing approach was developed to improve the assessment of geometric manufacturing and measurement deviations. This is based on a referencing system integrated in the powder bed, which enables a shortening of the measuring loop. The position-stable quartz glass pipes enable more precise specification of lateral manufacturing and measurement deviations during AM.

The development of optical design is characterized by the desire for more applications and better performance. The latest result of this development is freeform optics offering almost unlimited possibilities for the designers. However, an optical component has also to be manufactured and tested by metrology. We propose a measurement technique for the surface characterization of freeform optical components and highlight the possible error sources and their influence on the measurement result.

A new metrological atomic force microscope (MAFM) head design is shown. We investigated the MAFM head in the nanomeasuring machine (NMM-1) for different high-precision and large-scale traceable measurement tasks. Due to their integration, the MAFM head can benefit from the large measuring range, high-precision and traceability of the NMM-1 for efficient measurements on different samples. The presented results show the realised macroscale measurements with sub-nanometre resolution.

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.

The paper presents a concept for an automated classification of machine-readable data from measurement according to its agreement with metrological guidelines. An implementation of the classification was realized within the TraCIM online validation system for trustworthy certification of software that is under quality management. The research was collaboratively made by the partners of the European Metrology Research Project SmartCom.

A homemade experimental setup was developed using actuators and temperature sensors monitored by Arduino platforms to characterize thermal behaviors of composite panels containing phase-change materials (PCMs). The characterization is based on modeling steady-state thermal conduction and natural convection heat transfer. Temperature measurements allow for obtaining effective thermal conductivity, phase shift time, and energy storage capacity of composite panels incorporating PCMs.

We developed a smart in-cylinder pressure sensor for closed-loop combustion control. The sensor concept is based on a robust and reliable steel membrane equipped with highly strain-sensitive and temperature-stable thin films. The sensor system is complemented by a smart electronics allowing real-time data processing for calculation of different combustion parameters. The data are utilized to control the igniting timing of a spark plug for efficient operation of a combustion engine.

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.

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.