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STRATEGY FOR COMPENSATION OF THERMALLY INDUCED DISPLACEMENTS IN MACHINE STRUCTURES USING DISTRIBUTED TEMPERATURE FIELD CONTROL
No full text516Thermal deformation is a major source of machining errors in modern machine tools. In addition to optimising the machine structure, correcting the axis position values in the numerical control is a common measure to reduce these errors. Another possibility is to directly influence the temperature field of the machine tool in the process, which requires a complex thermo-elastic modelling approach as well as appropriate thermal actuation and measurement capabilities. This paper presents a strategy for controlling the temperature field based on the eigenmodes of the thermal system. The various aspects of the concept are explained using a finite element model of an exemplary structural component. The basis is the modal analysis of the thermal system, which allows the temperature field to be described by independent discrete states. In addition to the placement of thermal sensors and actuators, this work focuses on the design of a suitable control approach. Transient simulation results are used to clearly demonstrate the performance of this method.24
Adhesion-adapted polymer coating systems as filmic model systems for homogeneous geometry-independent surface coating for cleaning analyses
No full text610618In industrial parts cleaning and metal processing, there are currently no filmic model soiling’s that make it possible to generate homogeneous soiling films independent of geometry. However, this is essential for defined and reproducible cleaning tests. Polymer based coatings can close this gap. In the work presented here, a suitable optimised copolymer with carboxy groups as adhesive groups was developed and investigated for this application purpose. The polymer's cleaning behaviour, and therefore its adhesion, is adapted to that of a reference soiling. A fluorescent dye was attached to the polymer for subsequent detection and a dipping process was developed for the defined application of the copolymer. Comprehensive layer characterisation and systematic cleaning tests using ultrasound proved the reproducibility and uniformity of the generated layers. The residual layers of the polymer after each cleaning step could be quantified both by means of ellipsometry on smooth substrates and by measuring the fluorescence intensity. The process was extended to complex three-dimensional geometries and tested on cleaning systems in an industrial environment in order to validate the applicability, practicability, and efficiency of the developed method. The results show that the selected polymer concept provides a promising solution for the production of a uniform model soiling in component cleaning.15
Contribution of MASK-air® as an mHealth Tool for Digitally Enabled Person-Centered Care in Rhinitis and Asthma
No full text148156In chronic diseases, mHealth apps help to improve clinical management and provide valuable real-world scientific evidence. In allergic rhinitis, a market research study identified only 4 mHealth apps that were multilingual, resulted in scientific publications, and displayed a comprehensive list of medications. Of these 4 apps, MASK-air® generated the highest number of scientific publications. MASK-air was launched in 2015 and is currently available in 30 countries, with data collected from more than 30 000 users. It comprises a daily monitoring questionnaire, enabling patients to register their daily allergy symptoms by means of visual analog scales and their medication use. The achievements of MASK-air include the development of 2 digital biomarkers for daily monitoring of rhinitis and asthma (combined symptom-medication score and electronic daily asthma control score). MASK-air data have also made it possible to assess patients’ behavior, suggesting that patients do not follow guideline recommendations, but rather treat themselves (and often use comedication) when they feel worse. Using MASK-air data, we quantified the impact of allergic diseases on quality of life and school and work productivity. Real-world MASK-air data are being used as a source of evidence for the Allergic Rhinitis and its Impact on Asthma 2024 guidelines in an innovative process of incorporation of mobile health data into guidelines. This review discusses the clinical and scientific contributions of MASK-air to person-centred care of rhinitis and asthma, providing an illustrative example on the use of mHealth data in chronic diseases.34
Full D-Band GaN Power Amplifier MMIC and Waveguide Module
No full text5053In this article, we present a gallium nitride (GaN) power amplifier (PA) monolithic microwave integrated circuit (MMIC) and waveguide module that cover the full D-band (110-170 GHz) with a state-of-the-art performance. On-wafer measurements of the balanced ten-stage GaN PA show a small-signal gain of more than 13 dB over the full D-band and a peak output power of 22.6 dBm at 160 GHz. A two-way waveguide module delivers more than 18.5 dBm of output power over the full D-band with a peak of 25 dBm at 120 GHz. To the best of our knowledge, the reported amplifiers show the highest output power within GaN-based circuits beyond 140 GHz. This is also the first demonstration of GaN PAs covering the full D-band
Broadband InGaAs mHEMT THz Transmitters and Receivers
No full textWe describe THz amplifier and front-end modules that have been developed based on an InGaAs metamorphic HEMT (mHEMT) technology for THz-wireless communication applications around 300 GHz, covering the frequency range between 270 and 330 GHz and enabling record output-power levels above 10 dBm. Furthermore, we report on the development of state-of-the-art distributed mHEMT circuits with absolute bandwidths in excess of 300 GHz as building block of next-generation ultra-broadband THz front ends
UV-Stability of Industrial PERC, SHJ and TOPCon Solar Cells
No full text723725Recent reports suggest a pronounced susceptibility of modern cell architectures to degradation induced by ultraviolet irradiation (UVID). We investigate the stability of bifacial PERC, SHJ and TOPCon solar cells produced in-house and by industry by subjecting the bare cells to a UV dose of 60 kWh/m2. This treatment is comparable to almost 40 years of continuous UV-irradiation of the AM 1.5G spectrum with module glass and UV-blocking encapsulation. The loss in pseudo efficiency of all probed industry cells remains below 3%rel, for TOPCon even below 1%rel. When subjected to accelerated tests probing for light and elevated temperature induced degradation (LeTID), all industrial cells retain their high quality within a maximum deviation of 1%rel from the original pseudo efficiency. Our study shows that pathways to produce LeTID- and UVID-resistant solar cells based on modern technologies exist and are already known to some cell manufacturers
Evaluating task executability of mobile robots with performance maps
No full text3843Volatility in supply and demand caused by global disruptions such as wars or pandemics requires adaptable and changeable production systems. Since assembly accounts for significant production time and costs, the demand for changeable, line-less assembly systems is advancing. Controlling mobile robots in line-less assembly depends on understanding task executability. We propose the implementation of performance maps to evaluate the executability of assembly tasks within robot workspaces. Firstly, established performance metrics and typical assembly tasks are categorized to identify which metrics evaluate the executability of which type of tasks. The assembly tasks are grouped according to the type of movement (continuous or discrete), the required execution precision (high or low), and the amount of poses for execution (reachable or dexterous). The metrics are categorized according to their range (local or global), their physics (kinematic or dynamic), task reference (intrinsic or extrinsic), and scale (absolute or relative). Metrics are then matched to task types. This matching provides a systematic way to identify metrics to assess the executability of a task. Secondly, the performance map is presented. The performance map is a discretized representation of the distribution of chosen performance metrics for a specific robot. The current implementation is restricted to calculating the manipulability, dexterity, and condition number. Based on the input of a robot model and a task type, the metrics are calculated in distributed poses for a given resolution in the robot's workspace to form the performance map. The performance map is applied to exemplary tasks and robots. Previous approaches to workspace evaluation fail to consider the suitability of performance metrics to evaluate specific tasks, as different metrics are more or less relevant for different tasks. Consequently, the paper contributes by introducing performance maps and providing quantific metrics for comparing base placements of mobile robots according to the executability of specific assembly tasks
Utilizing Degeneracy in a Few-Mode Fiber to Demonstrate Entanglement Distribution
No full textThe degenerate modes of a few-mode fiber retain entanglement and allow for distribution over 50-km of single-mode fibers, paving the way for future research towards multi-port bidirectional beam splitters with a consistent coupling ratio across the C-band and over time, potentially maintaining hyperentanglement
Highly Efficient Inductor Design Using X-Winding Concept with Distributed Air Gaps
No full textThis work introduces a novel design method to reduce power losses caused by fringing fields in high-power-density inductors. By integrating circular clearances and distributed air gaps, the proposed design leverage fringing flux to uniform current distribution in the winding, thereby minimizing AC resistance. Compared to the conventional methods, the proposed method achieves both lowest core profile and AC resistance. In 3D finite element method (FEM) simulations, it achieves a 35% reduction in AC resistance compared to a conventional EE core design with a same box volume, and a 33% lower core profile than a conventional EI core design with even 15% lower AC resistance. Finally, the proposed X-winding concept is applied in printed circuit board (PCB) and the simulation results are verified by experimental measurements
Performance Degradation and Protective Effects of Atomic Layer Deposition for Mg-based Thermoelectric Modules
No full textThermoelectric technology has witnessed a resurgence in recent years due to increasing demands for sustainable energy sources and efficient cooling systems. Recently, the introduction of Te-free thermoelectric modules using non-toxic, abundant materials including p-type MgAgSb and n-type Mg3(Sb,Bi)2 marked a significant breakthrough. Despite promising performance, questions persist regarding long-term robustness and stability, especially in harsh environments. In this study, a thorough exploration of thermoelectric modules is conducted, focusing on their performance degradation under various conditions. Through elemental mapping analysis, degradation mechanisms are identified within the modules during cycling in argon environments, where atomic migrations and the formation of complex oxides at contact regions are key factors. Furthermore, cycling tests in air reveal significant degradation, prompting the exploration of protective strategies. Surface coatings using atomic layer deposition (ALD) emerge as a promising solution, particularly by HfO2, demonstrating superior protective effects. Furthermore, re-soldering effectively restores module performance is found, highlighting the importance of developing advanced soldering techniques to promote magnesium-based thermoelectric technology as a sustainable alternative to Bi2Te3. These findings emphasize the importance of exploring novel contact materials and demonstrate the potential of ALD as a universal approach to enhancing module reliability and robustness.344