Extrusion as an energy-efficient manufacturing process for thermoplastic organosheets. - In: Sheet Metal 2023, (2023), 43, S. 345-352
Organosheets combine the advantages of reinforcement fibers and thermoplastic polymers. By pairing these two materials, composites with outstanding mechanical properties and low densities can be produced. These semi-finished products can be further processed into complex and functionalized components by thermoforming or injection molding. There are a number of different manufacturing processes for continuous fiber reinforced thermoplastics (CFRT), however, most of them require long production times and recurrent melting of the polymer resulting in high energy and manufacturing costs. This study presents a novel extrusion process, that enables a continuous production of reinforced thermoplastic sheets with only one melting step. Due to the high energy efficiency and wide range of processible materials, this process shows a high potential for an economical production of CFRT. To investigate the extrusion process in more detail, the influence of the processing and the flow behavior of the polymer on the impregnation quality and the mechanical properties of the composites were studied. The results showed increasing fiber volume contents with lower polymer viscosities. Furthermore, higher die temperatures and pressures resulted in higher fiber volume contents and thus in higher mechanical properties. The experiments also revealed that a complete impregnation can currently not be achieved without an additional small double belt press due to the line load of the calender, the high viscosity of the melt and the short impregnation time.
https://doi.org/10.21741/9781644902417-43
Photon-induced near-field interaction in ultrafast low energy electron microscopy. - [Washington, D.C., USA] : Optica Publishing Group. - 1 Online-Ressource (Paper Tu3A.5)
We report the first observation of optical near-field coupling to an ultrafast wavepacket of free, low-energy electrons. Transient optical near-fields, highly spatially confined around a nanometer-sized Yagi-Uda-antenna are probed in a point-projection-microscope with 30-fs resolution.
https://doi.org/10.1364/UP.2022.Tu3A.5
Monitoring considerations of second life lithium ion batteries in battery energy storage systems. - In: PCIM Europe 2022, (2022), S. 1905-1914
This paper presents an analytical study of the most important technical aspects that should be considered in the methodologies for monitoring second-life lithium-ion batteries in stationary energy storage systems. The study is based, on one hand, on the specificity of these batteries in terms of changing their response differently in the second-life than in the first to external and operational influences. On the other hand, it is based on the monitoring requirements of storage systems to obtain an improved monitoring system with sufficient accuracy and more efficient performance of batteries in their second-life.
https://doi.org/10.30420/565822263
Incorporating state of charge estimation methods towards more accurate monitoring of second-life lithium-ion batteries. - In: 2022 13th International Renewable Energy Congress (IREC), (2022), insges. 6 S.
Although several methods are developed for estimating the state of charge of lithium-ion batteries, there is still a challenge regarding monitoring the second life of these batteries due to the expected difference in the behavior and operating conditions in their second life. Considering that each method has its advantages and disadvantages according to the application and operating conditions, and monitoring the batteries in their second life is of special importance because it is required to integrate with the battery management system to balance cells, diagnose faults and prevent overheating. Therefore, the estimation method developed in this study, by incorporating artificial neural network method and Kalman filter method with fine-tuning of the filtering process using Coulomb counting, provides a solution for more accurate online monitoring of these batteries. Aiming to get the best possible performance, considering the specificity of the second life of the batteries in terms of operating voltage, low values of expected capacity, discharge ratio and other operational parameters.
https://doi.org/10.1109/IREC56325.2022.10002052
Innovation processing of circuit boards with FDM printing and selective electrochemical metallization. - In: Meeting abstracts, ISSN 2151-2043, Bd. MA2022-01 (2022), 57, 2369
https://doi.org/10.1149/MA2022-01572369mtgabs
Precision meets high throughput - contactless single-cell sorting using an electrically passive microwell array. - In: 25th International Conference on Miniaturized Systems for Chemistry and Life Sciences (MicroTAS 2021), (2022), S. 135-136
Modern dielectrophoresis (DEP)-based microchips permit the isolation of pure single cells from heterogeneous cell mixtures. However, sorting throughputs and sample loading capacities are limited and active on-chip circuitry keeps the costs per sorted cell comparatively high. To overcome these problems, we have developed a novel DEP sorter consisting of a three-metal-layer microwell array. The entirely passive architecture of our device allows for inexpensive fabrication and universal sample input volumes. Nonetheless, experimental results revealed that our prototype exceeds the sorting speed of commercially available DEP sorters by at least one order of magnitude while maintaining single-cell precision and avoiding physical cell contact.
Fertigung magneto-mikrofluidischer Mikropumpen durch Kombination von Glas, Trockenfilm-Resist und 3D-Druck. - In: Mikrosystemtechnik, (2022), S. 69-72
Evaluation von MEMS-Führungskonzepten mit hohem Steifigkeitsverhältnis von Querrichtung und Hauptfunktionsrichtung. - In: Mikrosystemtechnik, (2022), S. 49-52
Mikrostrukturierte Spezialgläser für mikromechanische und mikrooptische Anwendungen. - In: Mikrosystemtechnik, (2022), S. 35-38
Study of the temperature behaviour in the polishing gap for different combinations of polishing pads and slurries. - In: Proceedings of the 22nd International Conference of the European Society for Precision Engineering and Nanotechnology, (2022), S. 509-512