TY - CHAP A1 - Herz, Jonas A1 - Sigrüner, Michael A1 - Muscat, Dirk A1 - Strübbe, Nicole T1 - Co-extruded polymer fibers for concrete reinforcement T2 - Proceedings of the 37th International Conference of the Polymer Processing Society (PPS-37) N2 - Corrosion of steel reinforcements in concrete constructions is a big topic for the building industry. Polymeric materials are a possible alternative due to their ability to withstand corrosion. To replace steel reinforcements, fibers with high mechanical properties and a good bonding ability between fiber and concrete are needed. Today different approaches for concrete reinforcement by polymer fibers have been investigated. The bonding ability of the fibers can be increased by mechanical anchoring, e.g. crimped or embossed fibers, as well as by a chemical bonding between concrete and fiber surface. To realize the requirements of high mechanical properties and a good bonding behavior, a fiber that is drawn from a co-extruded filament shall be produced and tested. The filament owns an innovative core-shell-structure. The core maintains the fiber-stiffness and the tensile strength while the shell allows using another material to affect the bonding behavior of the fiber. This study shows the usage of fibers with differing shell materials to examine their influence on the mechanical properties of the fiber in total and the adhesion abilities to concrete. As core material, an unfilled polypropylene (PP) is used. The shell materials are varied using different polymers e.g. polypropylene or ethylene acrylic acid copolymer, as well as two PP based compounds filled with wood particles and calcium carbonate blended with a maleic anhydride based coupling agent. The mechanical properties of the fibers are tested by fiber tensile tests to compare the younǵs modulus and the tensile strength. The influence of the shell phase on the bonding ability to concrete is evaluated by the interfacial shear strength calculated from single fiber pull-out tests. Microscopy is used to interpret changes before and after pull-out. The results depict incredible positive effects and allow new insights in possible materials for fiber reinforced concrete constructions. KW - polymer fibers KW - concrete reinforcement KW - coextrusion KW - core shell fiber Y1 - 2023 U6 - https://doi.org/10.1063/5.0168511 VL - 2884 IS - 1 ER - TY - JOUR A1 - Leiter, Nina A1 - Wohlschläger, Maximilian A1 - Versen, Martin T1 - Analysis of the phase-dependent fluorescence decay time of treated wood using FD-FLIM JF - tm - Technisches Messen N2 - For sustainable handling of wood and high material utilization, post-consumer wood has to be sorted by post-consumer wood categories in Germany. The non-destructive FD-FLIM method could improve the wood recycling process by automatic classification of waste wood into post-consumer wood classes. Thus, the phase-dependent fluorescence decay time of treated wood is analysed in this study to obtain the impact of the treatment on the fluorescence decay time. It is shown that treated and untreated wood can be differentiated using the fluorescence decay time, although the state-of-the-art theoretical fluorescence decay time differs from the experimentally determined fluorescence decay time. N2 - Für einen nachhaltigen Umgang mit Holz und eine hohe stoffliche Verwertung muss Altholz in Deutschland nach Altholzklassen sortiert werden. Die zerstörungsfreie FD-FLIM-Methode könnte den Holzrecyclingprozess durch eine automatische Klassifizierung von Altholz in Altholzklassen verbessern. Daher wird in dieser Studie die phasenabhängige Fluoreszenzabklingzeit von behandeltem Holz analysiert, um den Einfluss der Behandlung auf die Fluoreszenzabklingzeit zu ermitteln. Es wird gezeigt, dass behandeltes und unbehandeltes Holz anhand der Fluoreszenzabklingzeit unterschieden werden kann, auch wenn die nach dem Stand der Forschung theoretische Fluoreszenzabklingzeit von der experimentell ermittelten Fluoreszenzabklingzeit abweicht. KW - fluorescence KW - decay time KW - FD-FLIM KW - lifetime KW - wood Y1 - 2023 U6 - https://doi.org/10.1515/teme-2022-0114 VL - 90 IS - 6 SP - 401 EP - 406 ER - TY - JOUR A1 - Neumayer, Martin A1 - Stecher, Dominik A1 - Grimm, Sebastian A1 - Maier, Andreas A1 - Bücker, Dominikus A1 - Schmidt, Jochen T1 - Fault and anomaly detection in district heating substations: A survey on methodology and data sets JF - Energy N2 - District heating systems are essential building blocks for affordable, low-carbon heat supply. Early detection and elimination of faults is crucial for the efficiency of these systems and necessary to achieve the low temperatures targeted for 4th generation district heating systems. Especially methods for fault and anomaly detection in district heating substations are currently of high interest, as faults in substations can be repaired quickly and inexpensively, and smart meter data are becoming widely available. In this paper, we review recent scientific publications presenting data-driven approaches for fault and anomaly detection in district heating substations with a focus on methods and data sets. Our review indicates that researchers use a wide variety of methods, mostly focusing on unsupervised anomaly detection rather than fault detection. This is due to a lack of labeled data sets, preventing the use of supervised learning methods and quantitative analysis. Together with the lack of publicly available data sets, this impedes the accurate comparison of individual methods. To overcome this impediment, increase the comparability of different methods and foster competition, future research should focus on establishing publicly available data sets, and industry-relevant metrics as benchmarks. KW - District heating systems KW - Fault/anomaly detection KW - Machine learning Y1 - 2023 U6 - https://doi.org/10.1016/j.energy.2023.127569 VL - 276 SP - 127569 ER - TY - CHAP A1 - Schusser, Verena A1 - Sigrüner, Michael A1 - Bogner, Stefan A1 - Muscat, Dirk A1 - Strübbe, Nicole T1 - Effect of Fillers on the Mechanical Properties of Drawn Polypropylene Fibers T2 - International Conference on Composite Materials Belfast 2023 (ICCM 23), 30 July - 4 August 2023 KW - Filler Reinforcement KW - Filament KW - Fiber Draw Down Y1 - 2023 ER - TY - CHAP A1 - Seliger, Norbert T1 - A Differential Relaxation Half-Bridge Oscillator for Inductive Power Transfer T2 - Proceedings PCIM Europe 2023 N2 - We present inductive power transfer (IPT) with a half-bridge converter based on differential relaxation self-oscillation. The oscillation dynamics of the converter automatically adapts to variation in the inductive coupling link and changes in the load, respectively. Design equations based on theoretical circuit analysis reveals a high power transfer efficiency (>90%) for alteration of coupling distance in the strong coupling regime. A prototype system employing GaN-HEMTs confirms the theoretically predicted characteristics of the proposed circuit. KW - wireless power transfer, inductive power transfer, half-bridge converter, relaxation oscillator Y1 - 2023 PB - Mesago GmbH CY - Nürnberg ER - TY - JOUR A1 - Seliger, Norbert A1 - Faltlhauser, Georg T1 - Progressive Expansion Sampling of Quasi-Static Magnetic Fields in Unconfined Regions JF - IEEE Transactions on Components, Packaging and Manufacturing Technology N2 - We present a fast and accurate measurement technique for quasi-static magnetic fields by employing a progressive sampling method in an unconfined input space. The proposed machine learning algorithm is tested against uniform sampling on printed circuit board test structures and a buck converter. We prove allocation of multiple, separated regions with predefined lateral field limits at MHz frequencies. The feasibility of equivalent magnetic dipole source modeling based on a small number of samples is demonstrated. Compared to uniform testing, progressive expansion sampling identifies contours of given field limits in less than 3% of the reference measurement time. KW - Progressive Expansion Sampling KW - Near-Field Scanning KW - Machine Learning KW - Gaussian Process Classifier KW - MoM modeling Y1 - 2023 U6 - https://doi.org/10.1109/TCPMT.2023.3283285 ER - TY - CHAP A1 - Seliger, Norbert A1 - Faltlhauser, Georg T1 - Progressive Expansion Sampling of Quasi-Static Magnetic Fields for EMI Noise Detection and Equivalent Source Modeling T2 - Proceedings EMC Europe 2023 N2 - We introduce a quick and accurate quasi-static magnetic field scanning technique by employing a progressive sampling method in an unconfined input space. The proposed machine learning algorithm is tested against uniform sampling on a printed circuit board test structure. We prove allocation of multiple, separated regions with predefined tangential field strengths at MHz frequencies. The feasibility of equivalent magnetic dipole source modeling based on a small number of samples is demonstrated. Compared to uniform testing, progressive expansion sampling detects contours of given field limits in less than 3% of the reference measurement time. KW - magnetic near field KW - Gaussian process classifier KW - EMI Y1 - 2023 PB - IEEE CY - Krakov ER - TY - CHAP A1 - Seliger, Norbert A1 - Honsa, Johannes T1 - A Planar Magneto-Inductive Device with Modulated Mutual Inductance for Wireless Power Transmission T2 - 2023 IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications (APWC) N2 - A Magneto-Inductive Wave (MIW) structure for wireless power transfer (WPT) is proposed with switchable mutual inductance between neighbored coupling coils. Orthogonally placed switchable short circuit loops are added in order to modulate the wave propagation properties of the MIW structure without changing the resonance frequency. We derive an analytical model based on lumped circuit analysis for the MIW waveguide and successfully evaluate the theoretical findings by circuit modeling and field simulation. We demonstrate switchable, i.e. addressable, guided wireless power transfer along an experimental MIW structure at a resonance frequency of 20.5 MHz. KW - Magneto-Inductive Device, Wireless Power Transmission, Mutual Inductance Y1 - 2023 SN - 979-8-3503-2060-2 U6 - https://doi.org/10.1109/APWC57320.2023.10297488 SN - 2766-287X SP - 26 EP - 31 PB - IEEE CY - Venice (Italy) ER - TY - CHAP A1 - Seliger, Norbert A1 - Honsa, Johannes T1 - Time-variable Mutual Inductance for Enhanced Inductive Power Transmission T2 - Proceedings International Symposium on Fundamentals of Electrical Engineering 2023 (ISFEE 2023) N2 - Enhanced inductive power transmission (IPT) between coaxially arranged circular coils is introduced by time-modulation of the mutual inductance. This modulation is accomplished by coherent switching of the short circuit current induced in a third loop. An analytical circuit model supporting the design for future time-modulated IPT systems is derived. We demonstrate an increase in load rms-voltage by 13% (28% gain in power) compared to an unmodulated transfer on an experimental system operating at fundamental frequencies ranging from 40kHz to 500kHz. KW - Mutual Inductance KW - Inductive Power Transmission KW - Time-variable Inductance Y1 - 2023 SN - tbd PB - IEEE CY - Bucharest, Romania ER - TY - JOUR A1 - Sigrüner, Michael A1 - Hüsken, Götz A1 - Pirskawetz, Stephan A1 - Herz, Jonas A1 - Muscat, Dirk A1 - Strübbe, Nicole T1 - Pull-out behavior of polymer fibers in concrete JF - Journal of Polymer Science N2 - The bond between polymer fibers and the surrounding cementitious matrix is essential for the development of concrete reinforcement. The single fiber pull-out test (SFPT) is the standard characterization technique for testing the bond strength. However, the different phases of debonding cannot be distinguished by the SFPT. This study investigates the debonding of different polymer fibers from the surrounding cementitious matrix with a modified SFPT and proposes methods to change the SFPT setup to generate more valuable information on the debonding mechanism. The SFPT was equipped with linear variable differential transformers (LVDT), digital image correlation (DIC) and acoustic emission (AE) analysis. The results demonstrate that the modified SFPT allows a better understanding of the different phases of debonding during fiber pull-out. Furthermore, bond strength values calculated by different methods reveal that the chemical bond of the investigated polymers is not different as reported by previous studies. Deformation measurements performed using LVDTs and DIC are suitable measuring techniques to characterize the debonding mechanism in SFPT. A correlation between recorded AE and debonding phases was not found. KW - acoustic emission KW - bond behavior KW - polymer fibers KW - pull-out Y1 - 2023 U6 - https://doi.org/10.1002/pol.20230264 VL - 61 IS - 21 SP - 2708 EP - 2720 ER -