@inproceedings{HinterreiterBruecklRauch, author = {Hinterreiter, Marion and Br{\"u}ckl, Oliver and Rauch, Johannes}, title = {Challenges and Approaches for Long-Term Reactive Power Forecasting in Power Systems}, series = {PESS 2025 - IEEE Power and Energy Student Summit, October 08 - 10, 2025 in Munich, Germany}, booktitle = {PESS 2025 - IEEE Power and Energy Student Summit, October 08 - 10, 2025 in Munich, Germany}, editor = {Technische Universit{\"a}t M{\"u}nchen,}, publisher = {VDE Verlag}, isbn = {978-3-8007-6656-7}, pages = {109 -- 114}, abstract = {The transition from fossil fuels to renewable energy sources is driving profound changes across all voltage levels of the electrical grid, altering active power (P) as well as reactive power (Q) behavior. This transformation involves a shift from predominantly top-down, unidirectional electricity flows to bidirectional and increasingly complex flow patterns, fundamentally altering the operation and utilization of power systems. Many countries are already reporting notable changes in their transmission grid Q. This can lead to increased costs for grid expansion and compensation equipment, as well as grid losses. To minimize these losses and ensure grid stability and efficiency, understanding and forecasting Q long-term becomes essential. This paper addresses the challenges of long-term (1-20 years) Q forecasting in general by analyzing Q behavior in grids, the main influencing grid parameters, and reviewing existing forecasting approaches. It evaluates the applicability of these approaches and highlights current research gaps and trends. By focusing on this underexplored area, the paper aims to support the development of more advanced and reliable long-term Q forecasting techniques.}, language = {en} } @article{LambertKrausDoepfertetal., author = {Lambert, Jerry and Kraus, Hermann and Doepfert, Markus and He, Miaomiao and Gschossmann, David and Ceruti, Amedeo and Nemeth, Isabell and Br{\"u}ckl, Oliver and Hamacher, Thomas and Spliethoff, Hartmut}, title = {Assessing the techno-economic impact of district heating on electrical distribution grid reinforcements}, series = {Advances in Applied Energy}, volume = {20}, journal = {Advances in Applied Energy}, publisher = {Elsevier}, issn = {2666-7924}, doi = {10.1016/j.adapen.2025.100251}, pages = {21}, abstract = {Enhanced sector coupling across electricity, mobility, and heating sectors leads to higher efforts for distribution grid upgrades. Based on a case study, this paper evaluates the role of district heating networks in reducing electrical distribution grid reinforcements and compares their economic viability against a building-specific heat supply using heat pumps. A detailed energy system model is used to analyze two building energy renovation scenarios: a business-as-usual scenario with a 1 \% annual renovation rate and an ambitious scenario with a rate of 2 \%. Using a two-step optimization, the impact of different district heating network penetration levels on the distribution grid is evaluated, followed by an ex-post analysis to incorporate a simultaneity factor into district heating networks. Overall, district heating networks can reduce distribution grid reinforcements, but the associated savings alone do not justify their construction, particularly in the ambitious renovation scenario. In the business-as-usual scenario, a district heating network can reduce reinforcement costs by up to 71 \%. However, in the ambitious scenario, grid reinforcements are already reduced due to lower heat peak demand, and the maximal reinforcement cost savings only amount to 35 \%. Compared economically, district heating networks are cost-competitive with building-specific heating only in the business-as-usual scenario, up to a heat supply share of 70 \% and in the ambitious scenario, up to 40 \%. In both scenarios, a district heating network can be a robust solution to lower macroeconomic costs for a carbon-neutral heat supply.}, language = {en} } @misc{RillEiseltKelichhaus, author = {Rill, Georg and Eiselt, Uwe and Kelichhaus, Thomas}, title = {Vehicle dynamics with RecurDyn based on the TMeasy tire model}, series = {26th International Conference on Theoretical and Applied Mechanics (ICTAM), August 25-30, 2024, Daegu, Korea}, journal = {26th International Conference on Theoretical and Applied Mechanics (ICTAM), August 25-30, 2024, Daegu, Korea}, language = {en} } @article{TremmelNaglerKutteretal., author = {Tremmel, Florian and Nagler, Oliver and Kutter, Christoph and Holmer, Rainer}, title = {Double-Beam Cantilever Probe for Crack Probability Analysis of Multilayer Substrates During Wafer Probing}, series = {IEEE Sensors Journal}, volume = {24}, journal = {IEEE Sensors Journal}, number = {24}, publisher = {IEEE}, doi = {10.1109/JSEN.2024.3486355}, pages = {40295 -- 40304}, abstract = {During wafer testing, small probes are contacting pads on the wafer surface to check the chip functionality and identify faulty dies. To prevent damaging structures underneath, a mechanical load limit needs to be defined. This is done by intentionally overstressing the pads and searching for cracks that appear. A customized test bench with a patented sensor-indenter (SI) system is currently used to perform the contact cycles and identify crack formations in real time using the generated acoustic emissions (AEs). This method is faster and more accurate compared with previous optical detection methods. This article presents an improved version of the SI system usable in a wafer prober, featuring a double-beam cantilever beam with an exchangeable indenter tip. This leads to measurement conditions closer to productive wafer testing, enabling more accurate load limit definitions. The cantilever beam contains a strain gauge Wheatstone bridge for contact force measurement and a piezoelectric sensor element for AE signal detection. Amplifier circuits are designed for both sensors, and a data acquisition (DAQ) system is developed. A prototype of the sensor cantilever combination (SCC) is shown together with simulated and experimental results. The accuracy of the force sensor ( ±0.5 → ±1.3 mN) and the signal-to-noise ratios (SNRs) of the AE signals ( 29.1 → 21 dB) show only a small decrease compared with the previous SI system. A crack probability analysis of a test specimen confirms the usability of the SCC, as AE crack signals are detected at a similar mechanical load with both sensor setups.}, language = {en} } @article{SalamaKouDawoudetal., author = {Salama, Amgad and Kou, Jisheng and Dawoud, Belal and Simonson, Carey}, title = {A modeling approach for capillary-driven flow of a wetting fluid in a rectangular open microchannel of arbitrary axisymmetric width profile}, series = {International Journal of Thermal Sciences}, volume = {195}, journal = {International Journal of Thermal Sciences}, publisher = {Elsevier}, issn = {1290-0729}, doi = {10.1016/j.ijthermalsci.2023.108622}, pages = {17}, abstract = {Microchips are intensively used in almost all nowadays electronic devices. With the continuous advancement of our technologies, they get smaller in size than ever before. They generate high-intensity heat loads that need to be transported effectively such that they may function properly. Heat pipes have proven to be very effective in transporting relatively large heat loads from miniature components. They are of seamless structure that involves a working fluid capable of evaporation and condensation at the working temperature of the electronic chips. The working fluid is derived to move from the condenser to the evaporator via multiple microgrooves using capillary forces. It is important that the condensate reaches the evaporator at a proper rate such that no dry-out or flooding occur. In this work, we are particularly interested in the case of capillary-driven flows in rectangular microchannels. A generalized model is developed that works for axe-symmetric rectangular channels of arbitrary, moderately varying width profiles. It also accounts for any contrast of viscosity between the liquid and the vapor under isothermal conditions. The model shows to reduce to the special case of imbibition in straight and uniform microchannels, for which comparisons with experimental and modeling works show an excellent match. Cases representing linearly and quadratically varying converging/diverging width profiles have been explored. It is found that the viscosity ratio has a significant influence on the rate at which the meniscus advances. The model also negates the common practice found in the literature of using the formula developed for imbibition rates in capillary tubes for rectangular microchannels by replacing the diameter of the tube with the hydraulic diameter. It is also found that the channel profile has an influential effect on the imbibition rates. For tapered microchannels, the capillary force increases along the channel length while it decreases for diverging ones. It is interestingly demonstrated that, for quadratically tapered microchannel, the speed of the meniscus increases towards the end of the microchannel compared with linearly varying microchannels. On the other hand, for diverging microchannels, the speed of the meniscus decreases due to the increase in the cross-sectional area. Computational fluid dynamics (CFD) analysis has been conducted to provide a framework for confirmation and verification for which very good match has been established, which builds confidence in the modeling approach.}, language = {en} } @inproceedings{FuhrmannNiemetz, author = {Fuhrmann, Thomas and Niemetz, Michael}, title = {Analysis and Improvement of Engineering Exams Toward Competence Orientation by Using an AI Chatbot}, series = {Towards a Hybrid, Flexible and Socially Engaged Higher Education: Proceedings of the 26th International Conference on Interactive Collaborative Learning (ICL2023), Volume 1}, booktitle = {Towards a Hybrid, Flexible and Socially Engaged Higher Education: Proceedings of the 26th International Conference on Interactive Collaborative Learning (ICL2023), Volume 1}, publisher = {Springer Nature}, address = {Cham}, isbn = {9783031519789}, issn = {2367-3370}, doi = {10.1007/978-3-031-51979-6_42}, pages = {403 -- 411}, abstract = {ChatGPT is currently one of the most advanced general chatbots. This development leads to diverse challenges in higher education, like new forms of teaching and learning, additional exam methods, new possibilities for plagiarism, and many more topics. On the other side with the development of advanced AI tools, pure knowledge will be less and less important, and demands from industry will change toward graduates with higher competencies. Education has therefore to be changed from knowledge-centered toward competence centered. The goal of this article is to use ChatGPT for analyzing and improving the competence orientation of exams in engineering education. The authors use ChatGPT to analyze exams from different engineering subjects to evaluate the performance of this chatbot and draw conclusions about the competence orientation of the tested exams. The obtained information is used to develop ideas for increasing the competence orientation of exams. From this analysis, it is visible that ChatGPT gives good performance mainly where knowledge is tested. It has, however, much more problems with transfer questions or tasks where students need creativity or complex insights for finding new solutions. Based on this result, exams and also lectures can be optimized toward competence orientation.}, language = {en} } @inproceedings{RiegervandeParRabletal., author = {Rieger, Anna and van de Par, Steven and Rabl, Hans-Peter and Oetjen, Arne}, title = {Sch{\"a}rfeurteile f{\"u}r tonhaltige Ger{\"a}usche und die Konsequenzen f{\"u}r die instrumentelle psychoakustische Analyse}, series = {Fortschritte der Akustik - DAGA 2024, 50. Jahrestagung f{\"u}r Akustik, 18.-21. M{\"a}rz 2024 in Hannover}, booktitle = {Fortschritte der Akustik - DAGA 2024, 50. Jahrestagung f{\"u}r Akustik, 18.-21. M{\"a}rz 2024 in Hannover}, publisher = {Deutsche Gesellschaft f{\"u}r Akustik e.V. (DAGA)}, address = {Berlin}, isbn = {978-3-939296-22-5}, pages = {1210 -- 1213}, abstract = {In einer vorrangegangenen Studie wurde der Einfluss psychoakustischer Parameter auf Pr{\"a}ferenzurteile f{\"u}r konsonante und dissonante Ger{\"a}usche untersucht. Diese Ger{\"a}usche hatten die gleiche Lautheit und basierten auf einem festen Rauschhintergrund und eingebetteten hochfrequenten Tonkomponenten. Es zeigte sich, dass die Pr{\"a}ferenzurteile eines Probandenkollektives durch ebenfalls erhobene Subjektivurteile zu Sch{\"a}rfe, Tonhaltigkeit und Dissonanz mit hoher Pr{\"a}zision vorhergesagt werden konnten.Durch das angewandte Versuchsdesign konnte diese rein auf Subjektivbeurteilungen bestehende Vorhersage mit einer instrumentellen Vorhersage der Pr{\"a}ferenzurteile verglichen werden. Der Vergleich ergab einen niedrigeren Korrelationskoeffizienten f{\"u}r die modellbasierte Vorhersage, was auch durch die sehr niedrige Korrelation (R2<0,2) der berechneten Sch{\"a}rfe nach DIN45692 mit den Sch{\"a}rfe-Subjektivurteilen zu begr{\"u}nden war. Eine m{\"o}gliche Erkl{\"a}rung der unzureichenden Prognose der Sch{\"a}rfeurteile k{\"o}nnte in der Bewertungsstrategie der Proband:innen zu finden sein. F{\"u}r die getesteten Ger{\"a}usche mit auff{\"a}lligen tonalen Komponenten k{\"o}nnte statt der Sch{\"a}rfe des Gesamtger{\"a}uschs nur die Sch{\"a}rfe des tonalen Ger{\"a}uschobjekts ber{\"u}cksichtigt worden sein. Die Sch{\"a}rfe-Analyse der auf ihren tonalen Anteil reduzierten Signale zeigt eine sehr gute {\"U}bereinstimmung mit den Subjektivurteilen, was die Hypothese einer Trennung von Ton- und Rauschobjekten unterst{\"u}tzt. Es wird diskutiert, ob und wie das Paradigma der akustischen Objekttrennung in der Modellierung psychoakustischer Empfindungsgr{\"o}ßen Anwendung finden kann.}, language = {de} } @article{HeberlWithelmKauletal., author = {Heberl, Michael and Withelm, Christian and Kaul, Anja and Rank, Daniel and Sterner, Michael}, title = {Prospective Life Cycle Assessment of Biological Methanation in a Trickle-Bed Pilot Plant and a Potential Scale-Up}, series = {Energies}, volume = {17}, journal = {Energies}, number = {9}, publisher = {MDPI AG}, address = {Basel}, issn = {1996-1073}, doi = {https://doi.org/10.3390/en17092206}, abstract = {The fluctuating nature of renewable energies results in the need for sustainable storage technologies to defossilize the energy system without other negative consequences for humans and the environment. In this study, a pilot-scale trickle-bed reactor for biological methanation and various scale-up scenarios for 2024 and 2050 were investigated using life cycle assessment. A best- and worst-case scenario for technology development until 2050 was evolved using cross-consistency analysis and a morphological field, based on which the data for the ecological models were determined. The results show that the plant scale-up has a very positive effect on the ecological consequences of methanation. In the best-case scenario, the values are a factor of 23-780 lower than those of the actual plant today. A hot-spot analysis showed that electrolysis operation has an especially large impact on total emissions. The final Monte Carlo simulation shows that the technology is likely to achieve a low global warming potential with a median of 104.0 kg CO2-eq/MWh CH4 and thus can contribute to decarbonization.}, language = {en} } @unpublished{SchummAbdelKhalekBrownetal., author = {Schumm, Leon and Abdel-Khalek, Hazem and Brown, Tom and Ueckerdt, Falko and Sterner, Michael and Fioriti, Davide and Parzen, Max}, title = {The impact of temporal hydrogen regulation on hydrogen exporters and their domestic energy transition}, publisher = {Research Square Platform LLC}, doi = {10.21203/rs.3.rs-4285425/v1}, abstract = {As global demand for green hydrogen rises, potential hydrogen exporters move into the spotlight. However, the large-scale installation of on-grid hydrogen electrolysis for export can have profound impacts on domestic energy prices and energy-related emissions. Our investigation explores the interplay of hydrogen exports, domestic energy transition and temporal hydrogen regulation, employing a sector-coupled energy model in Morocco. We find substantial co-benets of domestic climate change mitigation and hydrogen exports, whereby exports can reduce domestic electricity prices while mitigation reduces hydrogen export prices. However, increasing hydrogen exports quickly in a system that is still dominated by fossil fuels can substantially raise domestic electricity prices, if green hydrogen production is not regulated. Surprisingly, temporal matching of hydrogen production lowers domestic electricity cost by up to 31\% while the effect on exporters is minimal. This policy instrument can steer the welfare (re-)distribution between hydrogen exporting firms, hydrogen importers, and domestic electricity consumers and hereby increases acceptance among actors.}, language = {en} } @article{TremmelNaglerKutteretal., author = {Tremmel, Florian and Nagler, Oliver and Kutter, Christoph and Holmer, Rainer}, title = {Mechanical robustness analysis of semiconductors with a single needle probe card using acoustic emissions}, series = {e-Journal of Nondestructive Testing}, volume = {29}, journal = {e-Journal of Nondestructive Testing}, number = {10}, publisher = {NDT.net}, issn = {1435-4934}, doi = {10.58286/30254}, abstract = {The combination of indentation testing and acoustic emission (AE) is widely used to analyze the fracture toughness of test substrates. In the manufacturing of semiconductor devices this material parameter also plays an important role. During the so-called wafer testing inside a wafer prober small probe tips are pressed onto the chip surface to check its performance. To prevent damaging the chip by that, the fracture toughness and load limit of it has to be defined in a prequalification step. This paper presents a test system that imitates the wafer testing process as close as possible and uses acoustic emission to detect appearing cracks and thereby also the load limit. The frontend of the test setup consists of a modular single needle probe card which can be placed in a wafer prober. Also, the indenter properties (tip diameter, stiffness, etc.) can be adjusted to the probe used later on during productive wafer testing to ensure realistic probing conditions. A piezoelectric sensor and a full strain gauge Wheatstone bridge are implemented close to the single indenter to measure the AEs and the applied contact force respectively. The signal-to-noise-ratios (SNRs) of both sensors are improved with an own analog amplifier module before recording them with an USB oscilloscope. A developed measurement software (LabVIEW) is used to adjust measurement parameters (trigger limit, record length, conversion factors, etc.) and automatically store and separate measurement data from different acoustic events and imprints. To evaluate the result files a second software tool (MATLAB) reads the files out and clusters the recorded events to separate crack signals from electrical and mechanical disturbances. With a prototype first test results are generated and the functionality and accuracy of the measurement concept is proven.}, language = {en} } @techreport{AndratschkeCeulloDawoudetal., author = {Andratschke, Christin and Ceullo, Laura and Dawoud, Belal and Draeger, Susan and Gerdes, Thorsten and Giebisch, Matthias and Grießhammer, Peter and Haas, Katharina and Haug, Sonja and Helling, Dominik and Kominis, Lena and Lang, Christian and Malz, Sebastian and Melzl, Johannes and Michlbauer, David and M{\"u}hlberger, Thomas and Nagl, Klaus and Preis, Michael and Rechenauer, Christian and Riederer, Michael and R{\"u}ckerl, Alexander and Saller, Tobias and Schnabl, Andreas and Stadler, Michael and Steffens, Oliver and Steininger, Peter and Stelzl, Andr{\´e} and Toutouly, Lovis and Trauner, Matthias and Vetter, Miriam and Walbrunn, Johannes and Weber, Karsten and Zielbauer, Lukas}, title = {MAGGIE: Energetische Modernisierung des genossenschaftlichen Wohnquartiers Margaretenau in Regensburg}, editor = {Steffens, Oliver}, address = {Regensburg}, isbn = {978-3-96256-100-0}, doi = {10.35096/othr/pub-5335}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-53354}, pages = {XVIII, 462 S.}, abstract = {Im Projekt MAGGIE wurden f{\"u}r das genossenschaftliche historische Stadtquartier „Margaretenau" in Regensburg Musterl{\"o}sungen f{\"u}r energieoptimiertes Wohnen mit innovativen Wandaufbauten aus solaraktiven Baukonstruktionen und einer vorhersagebasierten Versorgungstechnologie erforscht. Dazu wurde ein bestehendes Wohngeb{\"a}ude als Demonstrations- und Versuchsobjekt mit einem neuartigen, besonders effizienten Hybridsystem aus W{\"a}rmepumpentechnologie und Kraft- W{\"a}rme-Kopplung ausgestattet und untersucht, erg{\"a}nzt durch eine dynamische W{\"a}rmelogistik zur Verringerung von Verteilungsverlusten. Das System wurde durch ein neu entwickeltes, allgemein einsetzbares Planungs-, Optimierungs- und Steuerungstool ausgelegt und im Betrieb geregelt. Die in Echtzeit laufende Nachoptimierung des Systems w{\"a}hrend des Betriebs greift dabei auf reale Monitoringdaten zu. Die Einbindung von Nutzerbedarfsprofilen, Stromb{\"o}rse und Wetterdaten in die Steuerung gestattet einen dynamischen und perspektivischen Anlagenbetrieb zur Maximierung der Solar- und Umweltw{\"a}rme-Anteile der Energieversorgung und leistet damit einen wirksamen Beitrag zu einem emissionsarmen, klimafreundlichen Geb{\"a}udebetrieb. F{\"u}r die denkmalgerechte Modernisierung der historischen Fassaden wurde ein solaraktives und solaradaptives Außenputzsystem entwickelt und in der Realit{\"a}t getestet. Am Bestandsgeb{\"a}ude kam anstelle eines W{\"a}rmed{\"a}mmverbundsystems ein innovativer D{\"a}mmputz mit Mikrohohlglaskugeln zum Einsatz. Die Skalierbarkeit erlaubt eine abschnittsweise Modernisierung des gesamten Ensembles {\"u}ber mehrere Jahre. Durch die hohe Energieeffizienz wird die Warmmiete f{\"u}r die Bewohner der genossenschaftlichen Siedlung durch die Modernisierungsmaßnahmen nicht erh{\"o}ht, so dass auch nach der Modernisierung ein bezahlbares Wohnen sichergestellt wird.}, subject = {Altbaumodernisierung}, language = {de} } @article{HuberHeindlSchlosseretal., author = {Huber, Lea and Heindl, Melanie and Schlosser, Marc and Pfitzner, Arno and Dawoud, Belal}, title = {On the Cycle Stability and Macroscopic Structure of Iron Oxide Pellets for Thermochemical Hydrogen Storage: Influence of Water Content during the Pelletizing Process}, series = {Applied Sciences}, volume = {13}, journal = {Applied Sciences}, number = {11}, publisher = {MDPI}, address = {16}, doi = {10.3390/app13116408}, abstract = {Hydrogen storage based on the repeated reduction and oxidation (redox) reactions of iron oxide/iron composites represents a promising technology. This work is dedicated to studying the influence of the amount of water added during the pelletizing process on the cycle stability and structure of iron oxide pellets. The storage composites were prepared from iron oxide (Fe2O3) and 10 wt.-\% support material (cement) with different amounts of water (18 and 33 wt.-\%) in a laboratory-scale pelletizing disk. To evaluate the cycle stability of the composites, the kinetics of the redox reactions were experimentally measured at 800 ∘ C in an atmosphere of 50\% N2 and 50\% H2 (reduction) or 50\% steam (oxidation), respectively. Moreover, the structure of the pellets was analyzed by micro-computed tomography scans. It turned out that pellets with higher water contents attained faster kinetics and a higher cycle stability. The sample with the least water content (18 wt.-\%) needed about 26 min and 19 min to reach a conversion rate of 80\% during the reduction and oxidation reactions of the sixth redox cycle, respectively. In contrast, the sample with the highest water content (33 wt.-\%) could achieve the same conversion rate after 18 min (reduction) and 13 min (oxidation) during the ninth redox cycle.}, language = {en} } @article{MikhaeilGadererDawoud, author = {Mikhaeil, Makram and Gaderer, Matthias and Dawoud, Belal}, title = {On the application of adsorber plate heat exchangers in thermally driven chillers}, series = {Applied Thermal Engineering}, volume = {220}, journal = {Applied Thermal Engineering}, publisher = {Elsevier}, doi = {10.1016/j.applthermaleng.2022.119713}, abstract = {The effect of both heat and mass transfer characteristic lengths (HTCL, MTCL) of two different adsorber plate heat exchangers (APHE), for application in an adsorption chiller, on the adsorption and desorption kinetics is investigated. Three representative test frames (TF1-TF3) are prepared to examine small-scale adsorbent samples of the microporous silica gel (Siogel of Oker-Chemie, Germany) applying the volumetric large-temperature-jump methodology at different operating conditions. Based on the obtained kinetic data, an analytical model has been developed to predict the specific cooling power (SCP) and the coefficient of performance (COP) of a single-bed adsorption chiller comprising the studied APHEs. It turned out that, within the tested range of HTCL and MTCL, it can be concluded that, the adsorption kinetics are mainly influenced by the MTCL, while the desorption kinetics are dominated by the HTCL of the adsorbent domain. Applying Siogel as loose pellets inside a newly introduced APHE results in of 423.3 and 182.7 W⋅kg-1, at the evaporator temperatures of 15 °C and 5 °C, respectively. Herein, the condenser and adsorber-end temperatures amount to 30 °C and the desorption-end temperature to 90 °C. The corresponding s amount to 0.50 and 0.40, respectively, which represent quite promising results for further design optimizations.}, language = {en} } @techreport{ZacherlWopperMieslingeretal., author = {Zacherl, Florian and Wopper, Christoph and Mieslinger, Johann and Peis, Michael and Rabl, Hans-Peter}, title = {Schlussbericht zum Verbundvorhaben NAMOSYN: Nachhaltige Mobilit{\"a}t durch synthetische Kraftstoffe}, address = {Regensburg}, pages = {156}, abstract = {Im Labor f{\"u}r Verbrennungsmotoren und Abgasnachbehandlung der OTH-Regensburg sollten im Zuge des NAMOSYN-Projektes zwei Vertreter klimaneutraler Kraftstoffe an verschiedenen Systempr{\"u}fst{\"a}nden (Motor-, Einspritzpr{\"u}fstand, optisch zug{\"a}ngliche Einspritzkammer, …) und mit Hilfe von Simulationsmethoden f{\"u}r den Einsatz in bestehenden Verbrennungsmotoren untersucht werden. Synthetische Kraftstoffe aus der Gruppe der Oxymethylenether (OME) stellen eine CO2-neutrale Alternative zu fossilem Dieselkraftstoff dar. F{\"u}r Ottomotoren wurde untersucht, ob der synthetische Kraftstoff DMC/MeFo (Dimethylcarbonat \& Methylformiat) einen Ersatz f{\"u}r Ottokraftstoff darstellen kann, bzw. eine Drop-In-F{\"a}higkeit gegeben ist. Die OTH Regensburg bearbeitete 2 unabh{\"a}ngige Teilvorhaben zur motorischen Testung von synthetischen Kraftstoffen: „FC 1A: Motorische Testung von OME" und „FC 2: Untersuchung von C1-Oxygenaten f{\"u}r Ottomotoren". Die Projektlaufzeit betrug 3,5 Jahre, inkl. kostenneutraler Verl{\"a}ngerung um 6 Monate aufgrund der Corona-Pandemie. Im FC1A "AP2-Nachr{\"u}stung Dieselmotoren" der OTH Regensburg lag der Fokus auf der Erforschung der Potentiale und der Umr{\"u}stung eines Einzylinder-Dieselmotors mit Pumpe-Leitung-D{\"u}se-(PLD)-Einspritzsystem des Projektpartners Motorenfabrik Hatz GmbH und Co. KG f{\"u}r OME-Betrieb. Im AP2.1 wurden umfangreiche Daten gesammelt und Simulationsmodelle des Motors und PLD-Einspritzsystems erstellt und mit Dieselkraftstoff und OME validiert. Nachfolgend wurden Parameterstudien zur Geometrie des Einspritzsystems und der physikalischen Eigenschaften von OME durchgef{\"u}hrt. In AP2.2 und AP2.3 wurden umfangreiche Untersuchungen an einem Motor- und Einspritzsystempr{\"u}fstand mit Diesel und OME durchgef{\"u}hrt und der Steuerger{\"a}tedatensatz f{\"u}r den OME-Betrieb optimiert. Die Ergebnisse zeigen, dass die Umstellung des Kraftstoffs auf OME, insbesondere bei einfachen Motoren mit rudiment{\"a}rer Einspritztechnik und ohne Mittel zur NOx-Reduzierung (keine AGR oder SCR), ein enormes Potenzial zur Steigerung des Wirkungsgrads bei gleichzeitiger Reduzierung aller regulierten Schadstoffe (NOx, 𝑃N, 𝑃M, CO und 𝑉OC) er{\"o}ffnet. Die Ergebnisse und generierten Simulationsmodelle unterst{\"u}tzen eine schnelle Serienentwicklung und Einf{\"u}hrung von OME-Umr{\"u}stl{\"o}sungen. In FC 2 werden die vielversprechenden Kraftstoffe Methylformiat (MeFo) und Dimethylcarbonat (DMC) motorisch getestet. Untersuchungen am Kraftstoffsystem und wichtigen Komponenten dienen als Grundlage f{\"u}r das AP3. Im AP3 wird die Machbarkeit der DMC/MeFo-Verbrennung am Vollmotor demonstriert und die erwarteten Emissionsvorteile gegen{\"u}ber herk{\"o}mmlichen Ottokraftstoffen gezeigt. Abweichend von der urspr{\"u}nglichen Planung werden an der OTH Regensburg Kraftstoffblends aus Benzin und MeFo untersucht, um den Einsatzbereich des Kraftstoffs zu erweitern. In AP5 werden potentielle Mischungsverh{\"a}ltnisse analysiert und die Eigenschaften der ausgew{\"a}hlten Kraftstoffmischungen an einem Einspritzratenpr{\"u}fstand, an der Einspritzkammer und am Vollmotor untersucht. Es werden Einspritzverhalten, Gemischaufbereitung und Abgasemissionen bewertet. Zudem wird eine Kraftstoffmischanlage entwickelt und ein optischer Zugang am Vollmotor erm{\"o}glicht. Eine {\"O}lverd{\"u}nnungsmesstechnik wird eingesetzt, um den Kraftstoffeintrag ins Motor{\"o}l zu untersuchen}, language = {de} } @inproceedings{Rill, author = {Rill, Georg}, title = {Real-Time capable Multibody Model of dual Truck Front Axles}, series = {Proceedings of DINAME 2023 - Selected Papers of the XIX International Symposium on Dynamic Problems of Mechanics, 26 Feb - 03 Mar 2023, Piren{\´o}polis, Brazil}, booktitle = {Proceedings of DINAME 2023 - Selected Papers of the XIX International Symposium on Dynamic Problems of Mechanics, 26 Feb - 03 Mar 2023, Piren{\´o}polis, Brazil}, editor = {Fleury, Agenor de T.}, publisher = {Springer}, abstract = {Dual front steering axles are quite common in multi-axled heavy duty trucks. In standard layouts of such axle combinations, the steer motions of the wheels depend not only on the rotation of the steering wheel but also on the movements of the axles. As a consequence, the model complexity of the steering system should match with the complexity of the suspension model. The development of new technologies like advanced driver assistance systems or autonomous driving can only be accomplished efficiently using extensive simulation methods. Such kind of applications demand for computationally efficient vehicle models. This paper presents a steering system model for dual front axles of heavy duty trucks which supplements the suspension model of the axles. The model takes the torsional compliance of the steering column as well as the stiffness of the tie rods and the coupling rod into account. A quasi-static solution provides a straight forward computation including the partial derivatives required for an efficient implicit solver. The steering system model matches perfectly with comparatively lean, but sufficiently accurate multibody suspension models.}, language = {en} } @article{DePremekMottok, author = {De, Sangita and Premek, Brada and Mottok, J{\"u}rgen}, title = {Derivation of Optimized Threshold of Semantic Alignment Metrics for Intepretation of Interoperability and Reusability of Cross-enterprise Vehicle Service Interface Models}, series = {Informatica}, volume = {47}, journal = {Informatica}, number = {7}, publisher = {Slovenian Society Informatika}, issn = {0350-5596}, doi = {10.31449/inf.v47i7.4739}, abstract = {Over the past decade, cars have turned gradually into real cyber physical systems. The collaboration of services between the service-oriented, cross-enterprise vehicle application frameworks has increased to generate novel, smart and complicated vehicle services. Consequently, from an interoperability perspective, semantically mapping of vehicle service component's interface ontological models emerged as a big research interest in automotive application domain that manipulates several cross-enterprise synergy knowledge applications frameworks. The ontological metamodeling lays the foundation for building semantic bridge and exploring semantic associations between service components' interface models based on the domain knowledge for semantic interoperability. Also, several semantic quality metrics has been defined over time for the vehicle service interface ontological metamodels. The empirically evaluated values of these metrics can be used to assess progress in cross-enterprise interoperability between the service and the clients' APIs ontological models in vehicle domain. Despite potential benefits of semantic alignment quality metrics, the effective use of these metrics for vehicle service interface ontologies have proven elusive. Yes, such metrics can be used successfully for quantification, but then they mostly fail to provide adequate annotations in subsequent decision-making in the direction of semantic interoperability and reusability. The effective use of ontology semantic alignment quality metrics is basically hindered in the absence of the meaningful thresholds. In fact, the absence of an effective and meaningful threshold for the semantic similarity measure between various vehicle service interface ontological metamodels, motivates this research work which not only proposes a design approach to an optimized threshold for the semantic similarity metrics but also applies this threshold on few defined semantic alignment quality metrics. This paper also uses a real-world vehicle domain industrial case study to illustrate the design approach.}, language = {en} } @article{KeinerThomaBogdanovetal., author = {Keiner, Dominik and Thoma, Christian and Bogdanov, Dmitrii and Breyer, Christian}, title = {Seasonal hydrogen storage for residential on- and off-grid solar photovoltaics prosumer applications: Revolutionary solution or niche market for the energy transition until 2050?}, series = {Applied Energy}, volume = {340}, journal = {Applied Energy}, publisher = {Elsevier}, doi = {10.1016/j.apenergy.2023.121009}, pages = {17}, abstract = {Appropriate climate change mitigation requires solutions for all actors of the energy system. The residential sector is a major part of the energy system and solutions for the implementation of a seasonal hydrogen storage system in residential houses has been increasingly discussed. A global analysis of prosumer systems including seasonal hydrogen storage with water electrolyser, hydrogen compressor, storage tank, and a fuel cell studying the role of such a seasonal household storage in the upcoming decades is not available. This study aims to close this research gap via the improved LUT-PROSUME model, which models a fully micro sector coupled residential photovoltaic prosumer system with linear optimisation for 145 regions globally. The modelling of the cost development of hydrogen storage components allows for the simulation of a residential system from 2020 until 2050 in 5-year steps in hourly resolution. The systems are cost-optimised for either on- or off-grid operation in eight scenarios including battery electric vehicles, which can act as an additional vehicle-to-home electricity storage for the system. Results show that implementation of seasonal hydrogen systems only occurs in least cost solutions in high latitude countries when the system is forced to run in off-grid mode. In general, a solar photovoltaic plus battery system including technologies that can cover the heat demand is the most economic choice and can even achieve lower cost than a full grid supply in off-grid operation for most regions until 2050. Additional parameters including the self-consumption ratio, the demand cover ratio, and the heat cover ratio can therefore not be improved by seasonal storage systems if economics is the main deciding factor for a respective system. Further research opportunities and possible limitations of the system are then identified.}, language = {en} } @article{WalterSchwanzerHagenetal., author = {Walter, Stefanie and Schwanzer, Peter and Hagen, Gunter and Rabl, Hans-Peter and Dietrich, Markus and Moos, Ralf}, title = {Soot Monitoring of Gasoline Particulate Filters Using a Radio-Frequency-Based Sensor}, series = {Sensors}, volume = {23}, journal = {Sensors}, number = {18}, publisher = {MDPI}, issn = {1424-8220}, doi = {10.3390/s23187861}, pages = {1 -- 19}, abstract = {Owing to increasingly stringent emission limits, particulate filters have become mandatory for gasoline-engine vehicles. Monitoring their soot loading is necessary for error-free operation. The state-of-the-art differential pressure sensors suffer from inaccuracies due to small amounts of stored soot combined with exhaust gas conditions that lead to partial regeneration. As an alternative approach, radio-frequency-based (RF) sensors can accurately measure the soot loading, even under these conditions, by detecting soot through its dielectric properties. However, they face a different challenge as their sensitivity may depend on the engine operation conditions during soot formation. In this article, this influence is evaluated in more detail. Various soot samples were generated on an engine test bench. Their dielectric properties were measured using the microwave cavity perturbation (MCP) method and compared with the corresponding sensitivity of the RF sensor determined on a lab test bench. Both showed similar behavior. The values for the soot samples themselves, however, differed significantly from each other. A way to correct for this cross-sensitivity was found in the influence of exhaust gas humidity on the RF sensor, which can be correlated with the engine load. By evaluating this influence during significant humidity changes, such as fuel cuts, it could be used to correct the influence of the engineon the RF sensor.}, language = {en} } @inproceedings{Haumer, author = {Haumer, Anton}, title = {Modeling and Control Design of an Educational Magnetic Levitation System}, series = {Proceedings of the 15th International Modelica Conference 2023, Aachen, October 9-11}, booktitle = {Proceedings of the 15th International Modelica Conference 2023, Aachen, October 9-11}, publisher = {Link{\"o}ping University Electronic Press}, issn = {1650-3686}, doi = {10.3384/ecp204763}, abstract = {A magnetic levitation system is a perfect educational example of a nonlinear unstable system. Only with suitable control, a small permanent magnet can be held floating stable below a coil. After modeling and simulation of the system, control of the system can be developed. At the end, the control algorithm can be coded on a microcontroller, connected to a pilot plant.}, language = {en} } @techreport{SoergelLudererEmelianovaetal., author = {S{\"o}rgel, Dominika and Luderer, Gunnar and Emelianova, Polina and Koch, Otto and Timpe, Christof and Bauer, Franz and Sterner, Michael}, title = {Kopernikus-Szenarienvergleich - Robuste Eigenschaften von Klimaschutzpfaden zur Treibhausgasneutralit{\"a}t 2045 und relevante Unsicherheiten}, publisher = {Kopernikus-Projekte}, address = {Potsdam}, pages = {54 S.}, abstract = {Im Rahmen der vier Kopernikus-Projekte - Ariadne, ENSURE, P2X und SynErgie - wird die Transformation des deutschen Energiesystems hin zur Klimaneutralit{\"a}t analysiert. Im vorliegenden Bericht werden hierbei robuste Kernaussagen und relevante Unsicherheiten derjenigen Szenarien der Kopernikus-Schwesterprojekte dargestellt, die zur Zielsetzung die Klimaneutralit{\"a}t 2045 haben. Hierbei liegt der Fokus auf Indikatoren, die eine besonders hohe klimapolitische Relevanz haben.}, language = {de} } @article{GamischEttengruberGadereretal., author = {Gamisch, Bernd and Ettengruber, Stefan and Gaderer, Matthias and Dawoud, Belal}, title = {Dynamic simulation of isothermal and non-isothermal reduction and oxidation reactions of iron oxide for a hydrogen storage process}, series = {Renewable and Sustainable Energy}, volume = {1}, journal = {Renewable and Sustainable Energy}, number = {1}, publisher = {ELSP, International Open Science Platform}, doi = {10.55092/rse20230004}, abstract = {This work aims first to develop a dynamic lumped model for the isothermal reactions of hydrogen/steam with a single iron oxide/iron pellet inside a tubular reactor and to validate the model results against the experimental reaction kinetic data with the help of our STA device. To describe the temporal change in mass, and consequently, the temporal heat of reaction, the shrinking core model, based on the geometrical contracting sphere, is applied. It turned out that, the simulation model can reproduce the experimental, temporal concentration and temperature-dependent conversion rates with a maximum deviation of 4.6\% during the oxidation reactions and 3.1\% during the reduction reactions. In addition, a measured isothermal storage process comprising one reduction and one oxidation phase with a holding phase in between on a single reacting pellet could be reproduced with a maximum absolute deviation in the conversion rate of 1.5\%. Moreover, a lumped, non-isothermal simulation model for a pelletized tubular redox-reactor including 2kg of iron oxide pellets has been established, in which the heat of reaction, heat transfer to the ambient and heat transfer between the solid and gas phases are considered. The temporal courses of the outlet gas concentration as well as the temperatures of the gas stream and the solid material at a constant input gas flow rate and a constant reacting gas inlet concentration but different input gas temperatures are estimated. Because of the endothermic nature of the reduction reaction, the inlet reacting gas temperature shall be kept high to prevent the severe temperature drop in the solid phase and, consequently, the significant reduction of the reaction rate. Contrary to that, the oxidation process requires lower input gas temperatures to avoid the excessive overheating of the reaction mass and, consequently, the sintering of the reacting pellets. Finally, five of the previous reactors have been connected in series to explore the influence of the changing inlet gas temperatures and concentrations on the dynamic performance of each storage mass.}, language = {en} } @unpublished{TakayasuWeiklDahmenetal., author = {Takayasu, Anna and Weikl, Simone and Dahmen, Victoria and Bogenberger, Klaus}, title = {Impact of Travel Stress and Infrastructure Quality on Cycling Mode Share: Insights From Multimodal Trajectory and Survey Data Analysis}, publisher = {Researchgate}, doi = {10.13140/RG.2.2.30696.85766}, abstract = {This study explores the relationship between travel stress, infrastructure quality, and cycling mode share. Utilizing multimodal trajectory data, survey responses on travel stress, and detailed road network information with geological and bicycle facility data, the study analyzes correlations between actual and perceived infrastructure quality, travel stress, and cycling mode share, as well as the impact of travel time and distance on cycling mode share. The results indicate significant correlations between perceived infrastructure quality and travel stress levels, and between travel stress levels and cycling mode share, particularly among regular bike users. However, clear correlations between actual and perceived infrastructure quality, and between perceived infrastructure quality and cycling mode share, were not observed. Additionally, direct effects of travel time and distance on cycling mode share were not evident. From these findings, three main insights emerge. Firstly, accurately estimating cycling mode share requires considering multiple parameters beyond travel time and distance. Secondly, to implement effective measures for bicycle facilities, a detailed analysis of perceived infrastructure quality, incorporating actual infrastructure design, is crucial. Lastly, travel stress, when carefully assessed with consideration of various factors beyond infrastructure design, emerges as a key determinant of travel mode choice. These insights have significant implications for future cycling research, including the development of travel mode choice models and estimating cycling demand. The study's valuable contributions advance efforts to promote cycling as a sustainable and preferred mode of transportation.}, language = {en} } @inproceedings{SchweibererRauchBrueckl, author = {Schweiberer, Philipp and Rauch, Johannes and Br{\"u}ckl, Oliver}, title = {Control strategy for industrial reactive power sources depending on a specified reactive power setpoint value}, series = {ETG Kongress 2023: Die Energiewende beschleunigen, 25.-26. Mai 2023, Kassel, Germany}, booktitle = {ETG Kongress 2023: Die Energiewende beschleunigen, 25.-26. Mai 2023, Kassel, Germany}, publisher = {VDE VERLAG}, address = {Berlin}, organization = {Energietechnische Gesellschaft }, isbn = {978-3-8007-6108-1}, pages = {553 -- 558}, abstract = {Industrial plants can provide reactive power (Q) for system- and grid-serving behavior, for which a functioning reactive power management system is essential. To make reactive power retrieval as efficient and safe as possible, the selection of reactive power sources to meet the Q-demand must consider their sensitivities and the restrictions of the industrial grid, such as operating equipment utilization or voltage limits. On this basis, a concept for a sensitivity-based control strategy that manages the reactive power retrieval of multiple reactive power sources depending on a predefined reactive power demand value is proposed. Based on the simulation of an industrial plant in the medium-voltage grid, which can provide reactive power in the form of industrial compensation systems (ICS) and generators, the operation of the algorithm is shown.}, language = {en} } @article{HofrichterRankHeberletal., author = {Hofrichter, Andreas and Rank, Daniel and Heberl, Michael and Sterner, Michael}, title = {Determination of the optimal power ratio between electrolysis and renewable energy to investigate the effects on the hydrogen production costs}, series = {International Journal of Hydrogen Energy}, volume = {48}, journal = {International Journal of Hydrogen Energy}, number = {5}, publisher = {Elsevier}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2022.09.263}, pages = {1651 -- 1663}, abstract = {Green hydrogen via renewable powered electrolysis has a high relevance in decarbonization and supply security. Achieving economically competitive hydrogen production costs is a major challenge in times of an energy price crisis. Our objective is to show the economically optimal installed capacity of electrolysers in relation to wind and solar power so swift and credible statements can be made regarding the system design. The ratio between renewable generation and electrolysis power as well as scaling effects, operating behaviour and development of costs are considered. Hydrogen production costs are calculated for four exemplary real PV and wind sites and different ratios of electrolysis to renewable power for the year 2020. The ideal ratio for PV systems is between 14\% and 73\% and for wind between 3.3\% and 143\% for low and high full load hours. The lowest hydrogen production costs are identified at 2.53 €/kg for 50 MW wind power and 72 MW electrolysis power. The results provide plant constructors the possibility to create a cost-optimized design via an optimum ratio of electrolysis to renewable capacity. Therefore, the procedures for planning and dimensioning of selected systems can be drastically simplified.}, language = {en} } @inproceedings{GaertnerRankHeberletal., author = {G{\"a}rtner, Sebastian and Rank, Daniel and Heberl, Michael and Gaderer, Matthias and Sterner, Michael}, title = {Integration of Power-To-Methane into Glass Melting Processes}, series = {Proceedings of the International Renewable Energy Storage Conference (IRES 2022)}, volume = {16}, booktitle = {Proceedings of the International Renewable Energy Storage Conference (IRES 2022)}, publisher = {Atlantis Press}, issn = {2589-4943}, doi = {10.2991/978-94-6463-156-2_12}, pages = {147 -- 161}, abstract = {The glass industry is facing increased challenges regarding climate protection targets and rising energy costs. The integration of renewable energy including conversion and storage is a key for both challenges in this energy-intensive industrial sector, which has been mainly relying on fossil gas so far. The options considered to this point for reducing CO2 emissions and switching to a renewable energy supply involve far-reaching changes of the established melting processes. This entails significant risks in terms of influences on glass quality and stable production volumes. The presented approach for the integration of a Power-to-Methane (PtM) system into the glass industry is a completely new concept and has not been considered in detail before. It allows the use of established oxyfuel melting processes, the integration of fluctuating renewable energy sources and a simultaneous reduction of CO2 emissions by more than 78\%. At the same time, natural gas purchases become obsolete. A techno-economic evaluation of the complete PtM process shows, that 1,76 €/m3 or 1,26 €/kg synthetic natural gas are possible with renewable energy supply. Using electricity from the energy grid would require electricity prices < 0,126 €/kWh to allow cost competitive PtM processes in the glass industry. Such electricity prices could be achieved by electricity market-based optimization and operation of the PtM system. This operation strategy would require AI-based algorithms predicting availabilities and prices on future-based markets.}, language = {en} } @inproceedings{TremmelNaglerKutteretal., author = {Tremmel, Florian and Nagler, Oliver and Kutter, Christoph and Holmer, Rainer}, title = {Smart Cantilever Probe with Integrated Force and Acoustic Emission Sensor}, series = {2023 IEEE SENSORS, Vienna, Austria, 10/29/2023 - 11/1/2023}, booktitle = {2023 IEEE SENSORS, Vienna, Austria, 10/29/2023 - 11/1/2023}, publisher = {IEEE}, isbn = {979-8-3503-0387-2}, doi = {10.1109/SENSORS56945.2023.10325021}, pages = {1 -- 4}, abstract = {Acoustic emission (AE) testing recently found its application in the wafer testing sector of the semiconductor industry. To find out the mechanical robustness of semiconductor devices, contact pads on the chip surface are intentionally overstressed with an indenter tip and the appearing oxide cracks are detected with help of the generated AE signals. This is done in a customized test bench with a patented sensor-indenter system. This paper presents an improved version of the measurement setup that solves certain disadvantages of it and can be used in a standard wafer prober. The main components of the developed sensor system are a strain gauge for contact force measurement and a piezoelectric sensor element for AE signal detection. Both components are integrated on a cantilever beam which has an exchangeable indenter tip at its free end. The cantilever probe is electrically conductive to enable electrical tests via the indenter tip. This smart sensor-cantilever combination (SCC) can be mounted with several adapter components on a carrier plate to place it in a wafer prober. For both sensor elements amplifier circuits are developed to enhance their signal-to-noise ratios (SNRs). A prototype setup is shown together with simulated and experimental results to demonstrate its performance. The mechanical properties of the cantilever, as well as the force sensor and the AE crack signals, already fulfill the requirements for an implementation in a wafer prober. To further improve the sensor resolutions and detection limits, several optimizations regarding the design of the SCC are in progress.}, language = {en} } @unpublished{HeberlWithelmKauletal., author = {Heberl, Michael and Withelm, Christian and Kaul, Anja and Rank, Daniel and Sterner, Michael}, title = {Prospective Life Cycle Assessment of Biological Methanation in a Trickle-Bed Pilot Plant and a Potential Scale-Up}, publisher = {SSRN}, doi = {10.2139/ssrn.4635066}, abstract = {In this study, a pilot-scale trickle-bed reactor for biological methanation and various scale-up scenarios for 2023 and 2050 were investigated using LCA. A best- and worst-case scenario for technology development until 2050 was evolved using cross consistency analysis and morphological field, based on which the data for the ecological models were determined.The results show that the plant scale-up has a very positive effect on the ecological consequences of methanation. In the best-case scenario, the values are a factor of 23-780 lower than those of the actual plant today. A hot-spot analysis showed that especially electrolysis operation has a large impact on total emissions. The final Monte-Carlo simulation shows that the technology is likely to achieve a low GWP with a median of 104.0 kg CO2-eq / MWh CH4.}, language = {en} } @article{RillSchuderer, author = {Rill, Georg and Schuderer, Matthias}, title = {A Second-Order Dynamic Friction Model Compared to Commercial Stick-Slip Models}, series = {Modelling}, volume = {4}, journal = {Modelling}, number = {3}, publisher = {MDPI}, issn = {2673-3951}, doi = {10.3390/modelling4030021}, pages = {366 -- 381}, abstract = {Friction has long been an important issue in multibody dynamics. Static friction models apply appropriate regularization techniques to convert the stick inequality and the non-smooth stick-slip transition of Coulomb's approach into a continuous and smooth function of the sliding velocity. However, a regularized friction force is not able to maintain long-term stick. That is why dynamic friction models were developed in recent decades. The friction force depends herein not only on the sliding velocity but also on internal states. The probably best-known representative, the LuGre friction model, is based on a fictitious bristle but realizes a too-simple approximation. The recently published second-order dynamic friction model describes the dynamics of a fictitious bristle more accurately. It is based on a regularized friction force characteristic, which is continuous and smooth but can maintain long-term stick due to an appropriate shift in the regularization. Its performance is compared here to stick-slip friction models, developed and launched not long ago by commercial multibody software packages. The results obtained by a virtual friction test-bench and by a more practical festoon cable system are very promising. Thus, the second-order dynamic friction model may serve not only as an alternative to the LuGre model but also to commercial stick-slip models.}, language = {en} } @article{WalterSchwanzerHagenetal., author = {Walter, Stefanie and Schwanzer, Peter and Hagen, Gunter and Rabl, Hans-Peter and Dietrich, Markus and Moos, Ralf}, title = {Combined Ash and Soot Monitoring for Gasoline Particulate Filters Using a Radio-Frequency-Based Sensor}, series = {Emission Control Science and Technology}, journal = {Emission Control Science and Technology}, publisher = {Springer}, doi = {10.1007/s40825-023-00235-y}, pages = {9}, abstract = {Increasingly stringent emission limits have made particulate filters necessary for gasoline engines. Similar to diesel applications, gasoline particulate filters (GPFs) can be monitored by differential pressure measurement or by the radio-frequency-based filter diagnosis (RF sensor). In addition to measuring the soot loading, ash detection is critical for monitoring the GPF over the entire vehicle lifetime. Because the RF sensor detects the filter loading through a change in the dielectric properties of the GPF, it can detect not only soot but also ash. In diesel applications, the RF sensor has already demonstrated its potential for ash detection. To verify the feasibility of simultaneous ash and soot monitoring for GPFs, filters were loaded with ash on an engine test bench and measured on a lab test bench under defined synthetic exhaust gas conditions. By evaluating resonant modes, soot and ash could be clearly distinguished, as ash mainly affects the resonant frequency, while soot also changes the quality factor due to its high dielectric losses. However, higher soot loadings could not be detected by the resonant parameters, but instead by a frequency-averaged transmission signal. While the presence of ash caused an offset in this signal, its sensitivity to soot was not affected. Thus, the influence of ash can be corrected if the signal in the soot-free filter state is known, e.g., from the behavior of the resonant parameters. Therefore, even with a continuously increasing ash loading over the lifetime of a vehicle, an accurate soot detection is possible with the RF sensor.}, language = {en} } @misc{RahimSchumm, author = {Rahim, Stefan and Schumm, Leon}, title = {Weather Data Cutouts for the Wasserstoffatlas (Hydrogen Map) [Data set]}, doi = {10.5281/zenodo.8135586}, abstract = {The cutouts are required to calculate the solar PV and wind onshore feed-in profiles of the Wasserstoffatlas. The provided cutouts are spatiotemporal subsets of the European weather data from the ECMWF ERA5 reanalysis dataset and the CMSAF SARAH-2 solar surface radiation dataset for the year 2013. They have been prepared by and are for use with the atlite tool (https://atlite.readthedocs.io/). ECMWF ERA5 Source: https://cds.climate.copernicus.eu/cdsapp\#!/dataset/reanalysis-era5-single-levels?tab=overview Terms of Use: https://cds.climate.copernicus.eu/api/v2/terms/static/20180314_Copernicus_License_V1.1.pdf CMSAF SARAH-2 Pfeifroth, Uwe; Kothe, Steffen; M{\"u}ller, Richard; Trentmann, J{\"o}rg; Hollmann, Rainer; Fuchs, Petra; Werscheck, Martin (2017): Surface Radiation Data Set - Heliosat (SARAH) - Edition 2, Satellite Application Facility on Climate Monitoring, DOI:10.5676/EUM_SAF_CM/SARAH/V002, https://doi.org/10.5676/EUM_SAF_CM/SARAH/V002 Terms of Use: https://www.eumetsat.int/cs/idcplg?IdcService=GET_FILE\&dDocName=pdf_leg_data_policy\&allowInterrupt=1\&noSaveAs=1\&RevisionSelectionMethod=LatestReleased}, language = {en} } @inproceedings{RauchBruecklEngel, author = {Rauch, Johannes and Br{\"u}ckl, Oliver and Engel, Bernd}, title = {Optimal Reactive Power Planning by covering deficient voltage demands with additional reactive power sources using a sensitivity approach}, series = {NEIS 2023 : Conference on Sustainable Energy Supply and Energy Storage Systems, Hamburg, September 4 - 5, 2023}, booktitle = {NEIS 2023 : Conference on Sustainable Energy Supply and Energy Storage Systems, Hamburg, September 4 - 5, 2023}, editor = {Schulz, Detlef,}, publisher = {VDE Verlag}, address = {Berlin}, isbn = {978-3-8007-6134-0}, pages = {223 -- 230}, abstract = {The determination of the optimal location, types and size of additional required reactive power sources is a main interest of Reactive Power Planning (RPP) investigations and of this paper. The planning problem addresses the maintenance of voltage stability, which is an ancillary service in Germany, and can be formulated as a mixed-integer optimization prob-lem. The aim of this work is a techno-economically efficient coverage of the deficient steady state voltage deviation demands (VDD) by placing new reactive power sources with adequate size or extending the reactive power potential of existing sources. An optimization model is set up to solve the planning problem by using load flow voltage sensitivities, which quantify and evaluate the technical efficiency of new reactive power sources in relation to the present voltage deviation demands. Operating and investment costs are used as economic decision parameters. Within an application example, which is carried out with an exemplary transmission system, the solution of the planning problem is discussed.}, language = {en} } @phdthesis{Muehlbauer, author = {M{\"u}hlbauer, Christian}, title = {Entwicklung einer Methodik zur Bewertung und Optimierung des vibroakustischen Verhaltens von Kraftstoffeinspritzsystemen}, doi = {10.25673/109576}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:ma9:1-1981185920-1115312}, pages = {IX, 119}, abstract = {Die vorliegende Dissertation befasst sich mit der akustischen Analyse von Kraftstoffein-spritzsystemen und deren NVH-Optimierung mithilfe ansteuerungstechnischer Maßnahmen. Da sich der K{\"o}rper- und Luftschall beim Betrieb des Verbrennungsmotors mit anderen, nicht untersuchungsrelevanten Ger{\"a}uschkomponenten {\"u}berlagert, ist im Vollmotorbetrieb eine diffe-renzierte komponentenbasierte Ger{\"a}uschmessung nicht m{\"o}glich. Deshalb wurde ein NVH-Sys-tempr{\"u}fstand entwickelt, der eine isolierte akustische Vermessung von Einspritzsystemen im seriennahen Systemverbund erm{\"o}glicht. Die Betriebsparameter des Einspritzsystems wurden an einem Vollmotor in einem leerlaufna-hen Motorbetriebspunkt erfasst und mithilfe eines speziellen Entwicklungssteuerger{\"a}ts auf den NVH-Systempr{\"u}fstand transferiert. Ausgehend von dem definierten Referenzbetriebspunkt wurden sowohl die Randbedingungen als auch die Ansteuerstrategie variiert und deren Einfluss auf das akustische Verhalten analysiert. Dabei zeigten prim{\"a}r der Raildruck und die Anzahl der Einspritzungen einen ausgepr{\"a}gten Einfluss auf die betrachteten (psycho-)akustischen Parame-ter Schalldruckpegel, Lautheit, Sch{\"a}rfe und Impulshaltigkeit. Zur akustischen Optimierung der mechatronischen Komponenten wurden zum einen der An-steuerstrom reduziert und zum anderen ein Bremsimpuls am Ende der Ansteuerung implemen-tiert. Dadurch konnten die mechanischen Prellereignisse deutlich reduziert werden. Mithilfe eines Einspritzratenmessger{\"a}ts wurde allerdings nachgewiesen, dass sich die Optimierungs-maßnahmen insbesondere auf die Streuung der eingespritzten Kraftstoffmasse negativ auswir-ken und damit ein Zielkonflikt aus Ger{\"a}uschqualit{\"a}t und Prim{\"a}rfunktionen entsteht. Als signi-fikanter Kipppunkt wurde bei den Injektoren der {\"U}bergang vom linearen Vollhub-Betrieb zum ballistischen Teilhub-Betrieb identifiziert. Aus diesem Grund wurde die elektrische Ansteue-rung unter der Voraussetzung des Injektor-Vollhub-Betriebs optimiert. Bei der Beurteilung des Einflusses der NVH-optimierten Ansteuerprofile auf die Robustheit der mechatronischen Komponenten wirkten sich eine niedrige Versorgungsspannung sowie eine kurze Ansteuerdauer der Injektoren besonders negativ auf die Streuung der eingespritzten Kraftstoffmasse aus. Vor allem in Verbindung mit der stromreduzierten Ansteuerung wurden die Injektoren nicht mehr zuverl{\"a}ssig und reproduzierbar im Voll-Hub ge{\"o}ffnet. Weiterhin wur-den durch die Bremspuls-Applikation injektorspezifische Abweichungen im Schließverhalten weiter verst{\"a}rkt und erh{\"o}hten damit auch die Abweichungen der mittleren eingespritzten Kraft-stoffmasse zwischen den untersuchten Injektor-Exemplaren. Abschließend wurde die {\"U}bertragbarkeit des Systemverhaltens ermittelt, indem die Optimie-rungsmaßnahmen auf einen weiteren Versuchstr{\"a}ger ausgeweitet wurden. Dabei zeigte sich, dass die Maßnahmen zwar grunds{\"a}tzlich {\"u}bertragbar waren, aber die Parametrierung bez{\"u}glich Ansteuerstromreduzierung und Bremspuls-Applikation zum Teil stark angepasst werden mussten.}, language = {de} } @misc{ReindlErikssonNiemetzetal., author = {Reindl, Andrea and Eriksson, Lars and Niemetz, Michael and Sangyoung, Park and Meier, Hans}, title = {Control Concepts for a Decentralized Battery Management System Decentralized Battery Management System Global Control Level}, series = {16th International Renewable Energy Storage Conference (IRES2022), 20 to 22 September 2022, D{\"u}sseldorf}, journal = {16th International Renewable Energy Storage Conference (IRES2022), 20 to 22 September 2022, D{\"u}sseldorf}, publisher = {Eurosolar}, language = {en} } @article{SchaechingerBruecklBeckeretal., author = {Sch{\"a}chinger, J. and Br{\"u}ckl, Oliver and Becker, Mark and Lechner, Raphael}, title = {Results of the Research Project Optibiosy: Biogas plants as stabilizers of the power system?}, series = {BWK ENERGIE}, volume = {74}, journal = {BWK ENERGIE}, number = {11-12}, publisher = {VDI-Verlag}, address = {D{\"u}sseldorf}, issn = {1436-4883}, pages = {34 -- 39}, language = {en} } @article{WalterSchwanzerSteineretal., author = {Walter, Stefanie and Schwanzer, Peter and Steiner, Carsten and Hagen, Gunter and Rabl, Hans-Peter and Dietrich, Markus and Moos, Ralf}, title = {Mixing Rules for an Exact Determination of the Dielectric Properties of Engine Soot Using the Microwave Cavity Perturbation Method and Its Application in Gasoline Particulate Filters}, series = {Sensors}, volume = {22}, journal = {Sensors}, number = {9}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/s22093311}, pages = {1 -- 17}, abstract = {In recent years, particulate filters have become mandatory in almost all gasoline-powered vehicles to comply with emission standards regarding particulate number. In contrast to diesel applications, monitoring gasoline particulate filters (GPFs) by differential pressure sensors is challenging due to lower soot masses to be deposited in the GPFs. A different approach to determine the soot loading of GPFs is a radio frequency-based sensor (RF sensor). To facilitate sensor development, in previous work, a simulation model was created to determine the RF signal at arbitrary engine operating points. To ensure accuracy, the exact dielectric properties of the soot need to be known. This work has shown how small samples of soot-loaded filter are sufficient to determine the dielectric properties of soot itself using the microwave cavity perturbation method. For this purpose, mixing rules were determined through simulation and measurement, allowing the air and substrate fraction of the sample to be considered. Due to the different geometry of filter substrates compared to crushed soot samples, a different mixing rule had to be derived to calculate the effective filter properties required for the simulation model. The accuracy of the determined mixing rules and the underlying simulation model could be verified by comparative measurements on an engine test bench.}, language = {en} } @unpublished{GaertnerMarxSchubachGadereretal., author = {G{\"a}rtner, Sebastian and Marx-Schubach, Thomas and Gaderer, Matthias and Schmitz, Gerhard and Sterner, Michael}, title = {Introduction of an Innovative Energy Concept for low Emission Glass Melting based on Carbon Capture and Usage}, doi = {10.31224/2642}, abstract = {Due to the very high fossil energy demand, the glass industry is looking for innovative approaches for the reduction of CO2 emissions and the integration of renewable energy sources. In this paper, we present a novel power-to-gas concept, which has no impact on established melting processes and discuss it for this purpose. A special focus is set on the required CO2 capture from typical flue gases in the glass industry, as this process has not been investigated in detail yet. We used a process simulation approach to investigate post-combustion CO2 capture by absorption processes, followed by a techno-economic evaluation. Our investigations found the designed CO2 capture plant to be approx. 400 times smaller than absorption based CO2 separation processes for conventional power plants. Due to the many options for waste heat utilization, the waste heat required for CO2 desorption can be generated in a particularly efficient and cost-effective way. The resulting CO2 avoidance costs range between 41-42 €/t CO2, depending on waste heat utilization for desorption, and thus offer a cost effective way of CO2 removal from glass industry melting processes. These costs are well below the values of 50-65 €/t CO2 described so far for comparable industrial applications. In addition, we describe optimization options, like solvent and process improvements, to enable further cost reductions. These results motivate further research and development on the overall process presented in this work.}, language = {en} } @article{KaulBoellmannThemaetal., author = {Kaul, Anja and Boellmann, Andrea and Thema, Martin and Kalb, Larissa and Stoeckl, Richard and Huber, Harald and Sterner, Michael and Bellack, Annett}, title = {Combining a robust thermophilic methanogen and packing material with high liquid hold-up to optimize biological methanation in trickle-bed reactors}, series = {Bioresource technology}, volume = {345}, journal = {Bioresource technology}, publisher = {Elsevier}, doi = {10.1016/j.biortech.2021.126524}, abstract = {The hydrogen gas-to-liquid mass transfer is the limiting factor in biological methanation. In trickle-bed reactors, mass transfer can be increased by high flow velocities in the liquid phase, by adding a packing material with high liquid hold-up or by using methanogenic archaea with a high methane productivity. This study developed a polyphasic approach to address all methods at once. Various methanogenic strains and packings were investigated from a microbial and hydrodynamic perspective. Analyzing the ability to produce high-quality methane and to form biofilms, pure cultures of Methanothermobacter performed better than those of the genus Methanothermococcus. Liquid and static hold-up of a packing material and its capability to facilitate attachment was not attributable to a single property. Consequently, it is recommended to carefully match organism and packing for optimized performance of trickle-bed reactors. The ideal combination for the ORBIT system was identified as Methanothermobacter thermoautotrophicus IM5 and DuraTop (R).}, language = {en} } @article{SelmairMaurerLaietal., author = {Selmair, Maximilian and Maurer, Tobias and Lai, Chun-Han and Grant, David}, title = {Enhancing the efficiency of charging \& parking processes for Autonomous Mobile Robot fleets}, series = {Journal of Power Sources}, volume = {521}, journal = {Journal of Power Sources}, number = {3}, publisher = {Elsevier}, doi = {10.1016/j.jpowsour.2021.230894}, abstract = {The allocation of tasks to Autonomous Mobile Robots in a production setting in combination with the most efficient parking and charging processes are the focus of this paper. This study presents a simulative evaluation of the theoretical allocation methods developed in Selmair and Maurer (2020) combined with either hard or dynamic availability rules to ascertain the most efficient parameters of an Autonomous Mobile Robot System. In order to quantify this efficiency, the following Key Performance Indicator (KPI) were considered: number of delayed orders, driven fleet metres and the percentage of available Autonomous Mobile Robot as determined by their state of charge. Additionally, as an alternative energy source, a fast-charging battery developed by Battery Streak Inc. was included in this study. The results show that, in comparison to a conventional and commonly used trivial strategy, our developed strategies provide superior results in terms of the relevant KPI.}, language = {en} } @article{MikhaeilGadererDawoud, author = {Mikhaeil, Makram and Gaderer, Matthias and Dawoud, Belal}, title = {Experimental Investigation of the Adsorption and Desorption Kinetics on an Open-Structured Asymmetric Plate Heat Exchanger; Matching Between Small-Scale and Full-Scale Results}, series = {Frontiers in Energy Research}, volume = {10}, journal = {Frontiers in Energy Research}, publisher = {Frontiers}, doi = {10.3389/fenrg.2022.818486}, pages = {1 -- 15}, abstract = {This paper introduces the results of an experimental study on the adsorption and desorption kinetics of a commercially available, open-structured asymmetric plate heat exchanger adapted to act as an adsorber/desorber for the application in adsorption heat transformation processes. In addition, a volumetric large temperature jump (V-LTJ) kinetic setup was applied to measure the adsorption and desorption kinetics of a small-scale adsorbent sample prepared dedicatedly to be representative for the adsorbent domain inside the investigated adsorber plate heat exchanger (APHE). All kinetic results of the small-scale adsorbent sample and the APHE were fitted into exponential forms with a single characteristic time constant (τ) with a coefficient of determination (R2) better than 0.9531. A very good matching between the small-scale and full-scale adsorption kinetic measurements was obtained, with an average relative deviation of 12.3\% in the obtained τ-values. In addition, the kinetic data of the small-scale adsorbent sample were utilized for estimating the expected specific instantaneous and moving average powers of the evaporator/condenser heat exchanger. The average relative deviation (ARD) between the moving average specific evaporator powers obtained from the small-scale and the full-scale measurements amounts between 5.4 and 15.1\%.}, language = {en} } @inproceedings{BuenteRillRuggaberetal., author = {B{\"u}nte, Tilman and Rill, Georg and Ruggaber, Julian and Tobol{\´a}ř, Jakub}, title = {Modelling and Validation of the TMeasy Tyre Model for Extreme Parking Manoeuvres}, series = {Advances in Dynamics of Vehicles on Roads and Tracks II, Proceedings of the 27th Symposium of the International Association of Vehicle System Dynamics (IAVSD 2021): August 17-19, 2021, Saint Petersburg, Russia}, booktitle = {Advances in Dynamics of Vehicles on Roads and Tracks II, Proceedings of the 27th Symposium of the International Association of Vehicle System Dynamics (IAVSD 2021): August 17-19, 2021, Saint Petersburg, Russia}, editor = {Orlova, Anna and Cole, David}, publisher = {Springer}, address = {Cham}, isbn = {978-3-031-07305-2}, doi = {10.1007/978-3-031-07305-2_94}, pages = {1015 -- 1025}, abstract = {The TMeasy is a tyre model suitable for vehicle handling analyses and enables easy parametrisation. Recently, a convenient interface to Modelica was implemented by DLR to support the TMeasy also for vehicle modelling in multi-physical domains. This paper focuses especially on the particular problem of reliable reproduction of the tyre's bore torque which occurs during parking manoeuvres. It outlines the theory behind it, discusses the Modelica interface implementation, and presents the results of parameter identification which were achieved based on real experiments with DLR's research platform ROboMObil.}, language = {en} } @inproceedings{RiegerOetjenvandeParetal., author = {Rieger, Anna and Oetjen, Arne and van de Par, Steven and Rabl, Hans-Peter}, title = {Einfluss der Dissonanz auf die Wahrnehmung der Ger{\"a}uschqualit{\"a}t}, series = {Fortschritte der Akustik DAGA 2022: 48. Jahrestagung f{\"u}r Akustik, 21. - 24. M{\"a}rz 2022, Stuttgart und Online}, volume = {48}, booktitle = {Fortschritte der Akustik DAGA 2022: 48. Jahrestagung f{\"u}r Akustik, 21. - 24. M{\"a}rz 2022, Stuttgart und Online}, publisher = {Deutsche Gesellschaft f{\"u}r Akustik e.V.}, address = {Stuttgart}, language = {de} } @article{EmbergerAltmannGebhardetal., author = {Emberger, Peter and Altmann, Robert and Gebhard, J{\"u}rgen and Thuneke, Klaus and Winkler, Markus and T{\"o}pfer, Georg and Rabl, Hans-Peter and Remmele, Edgar}, title = {Combustion characteristics of pure rapeseed oil fuel after injection in a constant volume combustion chamber with a non-road mobile machinery engine solenoid injector}, series = {Fuel}, journal = {Fuel}, number = {320}, publisher = {Elsevier}, doi = {10.1016/j.fuel.2022.123979}, abstract = {Pure rapeseed oil fuel (R100) according to standard DIN 51605 is a greenhouse gas saving option for the mobility sector. With its high energy density close to diesel fuel, R100 is suitable to operate non-road mobile machinery with a high power demand and long operating time, where electric drives reach their limits. Advantages are indicated for its use in environmentally sensitive areas like agriculture since R100 is highly biodegradable and non-toxic. However, R100 is characterised by differing physical and chemical properties compared to diesel. The objective of the research is to investigate the differences in the ignition and combustion behaviour of R100 compared to diesel fuel (DF). For this purpose, a constant volume combustion chamber is used, which is equipped with a modern solenoid injector for engines of non-road mobile machinery. The researched injector shows a different hydraulic behaviour when using R100 compared to DF in that the injected fuel mass is lower with R100 than with DF. In combination with the 14 \% by mass lower calorific value, less energy output is determined with R100. When varying the injection pressure, the impact on the ignition delay and combustion behaviour is much higher for R100 than for DF. Specifically, an increase of the injection pressure supports mixture preparation and thus partially compensates the differing physical properties of R100. The results of ignition delay measurements and net heat release analysis are as follows: At low load conditions with low injection pressure as well as a low combustion chamber temperature and pressure, R100 ignites later and shows a further delayed combustion compared to diesel. The opposite is observed for medium and high load conditions, where R100 ignites faster and without delayed combustion in comparison to DF. Thus, an adjustment of the heat release of R100 at the same level as for DF is possible by modifying the injection strategy. The research shows that for an optimised combustion of R100 the injection settings must be adjusted for every operation point separately. The results indicate how the injection parameters should be adjusted for different load conditions to realise a high-quality engine calibration for R100.}, language = {en} } @inproceedings{Rill, author = {Rill, Georg}, title = {A Three-Dimensional and Nonlinear Virtual Test Car}, series = {ENOC 2022, book of abstracts, 10th European Nonlinear Dynamics Conference: July 17-22, 2022, Lyon, France}, booktitle = {ENOC 2022, book of abstracts, 10th European Nonlinear Dynamics Conference: July 17-22, 2022, Lyon, France}, address = {Lyon}, pages = {49 -- 58}, abstract = {Virtual testing procedures have become a standard in vehicle dynamics. The increasing complexity of driver assistance sys- tems demand for more and more virtual tests, which are supposed to produce reliable results even in the limit range. As a consequence, simplified vehicle models, like the classical bicycle model or 4-wheel vehicle models, have to be replaced by a fully three-dimensional and nonlinear vehicle model, which also encompasses the details of the suspension systems. This paper presents a passenger car model, where the chassis, the four knuckles, and the four wheels are described by rigid bodies, the suspension system is modeled by the generic design kinematics, and the TMeasy tire model provides the tire forces and torques in all driving situations.}, language = {en} } @inproceedings{ArrietaCastroRill, author = {Arrieta Castro, Abel and Rill, Georg}, title = {Kinematic Versus Elasto-Kinematic Model of a Twistbeam Suspension}, series = {Advances in Dynamics of Vehicles on Roads and Tracks II, proceedings of the 27th Symposium of the International Association of Vehicle System Dynamics (IAVSD 2021): August 17-19, 2021, Saint Petersburg, Russia}, booktitle = {Advances in Dynamics of Vehicles on Roads and Tracks II, proceedings of the 27th Symposium of the International Association of Vehicle System Dynamics (IAVSD 2021): August 17-19, 2021, Saint Petersburg, Russia}, editor = {Orlova, Anna and Cole, David}, publisher = {Springer Nature}, doi = {10.1007/978-3-031-07305-2_59}, pages = {505 -- 605}, abstract = {The Twistbeam axle suspension is a cheap and robust layout for rear axles at front wheel driven midsize cars. Appropriate models have to take the elastic deformation of the torsion beam into account. A Finite Element approach requires detailed informations of the material properties and the shape which are usually only available in the final production stage. This paper presents a lumped mass model which can easily be integrated into a multibody vehicle model and can be used in the early stage of development. An approximation by the design kinematics further reduces the complexity of the model and considers only the kinematic properties of the Twistbeam suspension. Simulations using a nonlinear and three-dimensional vehicle model with different maneuvers, such as steady-state cornering, step steer input, and driving straight ahead on random road, demonstrate the performance and, in particular, the difference of the presented Twistbeam suspension models.}, language = {en} } @inproceedings{WagnerAlAbadiBuchner, author = {Wagner, Marcus and Al-Abadi, Ali and Buchner, Stefan}, title = {A Numerical-Based Model to Determine the Resonance of the Steel Cores of Transformers}, series = {ARWtr 2022 proceedings : 2022 7th Advanced Research Workshop on Transformers (ARWtr), October (23)24-26, 2022, Baiona, Spain}, booktitle = {ARWtr 2022 proceedings : 2022 7th Advanced Research Workshop on Transformers (ARWtr), October (23)24-26, 2022, Baiona, Spain}, editor = {L{\´o}pez-Fern{\´a}ndez, Xose M.,}, publisher = {IEEE}, isbn = {978-84-09-45157-9}, doi = {https://doi.org/10.23919/ARWtr54586.2022.9959938}, pages = {36 -- 41}, abstract = {The laminated steel core of transformers is one of the main sources of the generated sound, as it is excited by different electromagnetic effects during its normal operation. If the core is excited in its eigenfrequencies, the sound generated by a transformer will increase significantly. Therefore, knowledge of the core's eigenmodes and -frequencies in an early design stage can decrease expenses by avoiding costly modifications that might be required to avoid the sound levels exceeding the specified values after the final factory acceptance test. The current study focuses on developing a core resonance model to determine the eigenmodes and -frequencies of a transformer core. The core's geometry was simplified to a connected-beam structure and a numerical-based approach was applied. The accuracy of the developed model was validated against finite element method (FEM), using ANSYS on a reference core model.}, language = {en} } @inproceedings{KoernerReindlMeieretal., author = {K{\"o}rner, Patrick and Reindl, Andrea and Meier, Hans and Niemetz, Michael}, title = {A Theoretical Comparison of Different Virtual Synchronous Generator Implementations on Inverters}, series = {2022 24th European Conference on Power Electronics and Applications (EPE'22 ECCE Europe): 05-09 September 2022, Hannover, Germany}, booktitle = {2022 24th European Conference on Power Electronics and Applications (EPE'22 ECCE Europe): 05-09 September 2022, Hannover, Germany}, publisher = {IEEE}, pages = {9}, abstract = {The goal to overcome the global climate crisis leads to a rising demand for the usage of Renewable Energy Sources (RES). Decentralized control strategies are needed to allow the integration of RES into the grid. The Virtual Synchronous Generator (VSG) is proposed as a method to add virtual inertia to the grid by emulating the rotating mass of a Synchronous Generator (SG) on the control algorithm of an inverter. This paper presents the VSG control structure as well as the mathematical description in a unified form. Due to the fact that classical droop control can be seen as a special form of the VSG, their correlation is highlighted by evaluating the steady state output characteristics of the inverter. Furthermore, a theoretical comparison between different VSG topologies, including the VISMA-Method 2 and the synchronverter, is given. In order to achieve better voltage stability, principles to add virtual impedance to the inverter's output are described.}, language = {en} } @inproceedings{LaloSailerMottoketal., author = {Lalo, Erjola and Sailer, Andreas and Mottok, J{\"u}rgen and Siemers, Christian}, title = {Overhead-Aware Schedule Synthesis for Logical Execution Time (LET) in Automotive Systems}, series = {2022 IEEE 35th International System-on-Chip Conference (SOCC): 05-08 September 2022, Belfast, United Kingdom}, booktitle = {2022 IEEE 35th International System-on-Chip Conference (SOCC): 05-08 September 2022, Belfast, United Kingdom}, publisher = {IEEE}, isbn = {978-1-6654-5985-3}, doi = {10.1109/SOCC56010.2022.9908103}, pages = {1 -- 6}, abstract = {The Logical Execution Time (LET) has recently been integrated in multi-core automotive systems to ensure timing and dataflow determinism. Although buffering mechanisms are introduced to incorporate LET semantics, they do not guarantee that tasks are executed within their LET frames. In fact, LET and buffering semantics are violated if scheduling is not designed to execute all tasks within their LET frames and in a specific order. In this paper, we describe a scheduling synthesis technique for Fixed-Priority Scheduling (FPS) to achieve resource-efficient execution of LET systems. The proposed approach considers LET semantics, scheduling overheads, and delays caused by operating system operations and provides the possibility to optimize the schedule with respect to aspects like scheduling overheads. Our performance and feasibility evaluation shows that the proposed algorithm provides results in a reasonable amount of time for models of complex industrial applications. Thus, the integration of the proposed algorithm into an automated process is of high benefit to accelerate the development of vehicle applications.}, language = {en} } @incollection{BauerGawlikSterneretal., author = {Bauer, Franz and Gawlik, Julia and Sterner, Michael and Hamacher, Thomas}, title = {{\"U}bergreifende Energiesystemmodellierung}, series = {Optionen f{\"u}r ein nachhaltiges Energiesystem mit Power-to-X-Technologien: Transformation - Anwendungen - Potentiale. 4. Roadmap des Kopernikus-Projektes P2X, Phase II}, booktitle = {Optionen f{\"u}r ein nachhaltiges Energiesystem mit Power-to-X-Technologien: Transformation - Anwendungen - Potentiale. 4. Roadmap des Kopernikus-Projektes P2X, Phase II}, editor = {Ausfelder, Florian and Du Tran, Dinh}, publisher = {DECHEMA Gesellschaft f{\"u}r Chemische Technik und Biotechnologie e.V.}, address = {Frankfurt a.M.}, isbn = {978-3-89746-238-0}, pages = {17 -- 35}, language = {de} } @inproceedings{WagnerLehrerFrankeetal., author = {Wagner, Marcus and Lehrer, Tobias and Franke, Markus and Al-Abadi, Ali and Gamil, Ahmed}, title = {A Tank Resonance Model for Power Transformers}, series = {ARWtr 2022 proceedings, 2022 7th Advanced Research Workshop on Transformers (ARWtr): October (23)24-26, 2022, Baiona, Spain}, booktitle = {ARWtr 2022 proceedings, 2022 7th Advanced Research Workshop on Transformers (ARWtr): October (23)24-26, 2022, Baiona, Spain}, publisher = {IEEE}, organization = {Institute of Electrical and Electronics Engineers (IEEE)}, doi = {10.23919/ARWtr54586.2022.9959917}, pages = {7 -- 12}, abstract = {During the factory acceptance test, the sound levels are measured. If the measured sound levels exceed pre-specified values, modifications on the transformer's active part and/or tank need to be conducted. Tank resonance, if occurs, at twice main power frequency and its higher harmonics is one of the main reasons of amplifying the generated sound levels. Therefore, it is preferable to know already in the design stage about the occurrence of the tank resonance and propose reliable tank solutions. The current study presents a newly developed model for calculating the mode shapes and its corresponding eigenfrequencies of the tank.}, language = {en} } @article{GamischHuberGadereretal., author = {Gamisch, Bernd and Huber, Lea and Gaderer, Matthias and Dawoud, Belal}, title = {On the Kinetic Mechanisms of the Reduction and Oxidation Reactions of Iron Oxide/Iron Pellets for a Hydrogen Storage Process}, series = {Energies}, volume = {15}, journal = {Energies}, number = {21}, publisher = {MDPI}, doi = {10.3390/en15218322}, abstract = {This work aims at investigating the kinetic mechanisms of the reduction/oxidation (redox) reactions of iron oxide/iron pellets under different operating conditions. The reaction principle is the basis of a thermochemical hydrogen storage system. To simulate the charging phase, a single pellet consisting of iron oxide (90\% Fe2O3, 10\% stabilising cement) is reduced with different hydrogen (H2) concentrations at temperatures between 600 and 800 °C. The discharge phase is initiated by the oxidation of the previously reduced pellet by water vapour (H2O) at different concentrations in the same temperature range. In both reactions, nitrogen (N2) is used as a carrier gas. The redox reactions have been experimentally measured in a thermogravimetric analyser (TGA) at a flow rate of 250 mL/min. An extensive literature review has been conducted on the existing reactions' kinetic mechanisms along with their applicability to describe the obtained results. It turned out that the measured kinetic results can be excellently described with the so-called shrinking core model. Using the geometrical contracting sphere reaction mechanism model, the concentration- and temperature-dependent reduction and oxidation rates can be reproduced with a maximum deviation of less than 5\%. In contrast to the reduction process, the temperature has a smaller effect on the oxidation reaction kinetics, which is attributed to 71\% less activation energy (Ea,Re=56.9 kJ/mol versus Ea,Ox=16.0 kJ/mol). The concentration of the reacting gas showed, however, an opposite trend: namely, to have an almost twofold impact on the oxidation reaction rate constant compared to the reduction rate constant.}, language = {en} }