@incollection{KralHaumerGrabner, author = {Kral, Christian and Haumer, Anton and Grabner, Christian}, title = {Determination of Consistent Induction Motor Parameters}, series = {Electronic Engineering and Computing Technology}, volume = {60}, booktitle = {Electronic Engineering and Computing Technology}, editor = {Ao, Sio-Iong and Gelman, Len}, publisher = {Springer}, address = {Dordrecht}, isbn = {978-90-481-8775-1}, doi = {10.1007/978-90-481-8776-8_7}, pages = {71 -- 80}, abstract = {From the rating plate data of an induction motor the nominal efficiency can be determined. Without detailed knowledge of equivalent circuit parameters, partial load behavior cannot be computed. Therefore, a combined calculation and estimation scheme is presented, where the consistent parameters of an equivalent circuit are elaborated, exactly matching the nominal operating point. From these parameters part load efficiencies can be determined.}, language = {en} } @incollection{KralHaumerGrabner, author = {Kral, Christian and Haumer, Anton and Grabner, Christian}, title = {Broken Rotor Bars in Squirrel Cage Induction Machines - Modeling and Simulation}, series = {Electronic Engineering and Computing Technology}, booktitle = {Electronic Engineering and Computing Technology}, editor = {Ao, Sio-Iong and Gelman, Len}, publisher = {Springer}, address = {Dordrecht}, isbn = {978-90-481-8775-1}, doi = {10.1007/978-90-481-8776-8_8}, pages = {81 -- 91}, abstract = {This paper presents a physical model of a squirrel cage induction machine with rotor topology. The machine is modeled in Modelica, an object oriented multi physical modeling system. The presented machine model is used to investigate electrical rotor asymmetries in induction machines. For the case of a single broken rotor bar a simulation model is compared with measurement results.}, language = {en} } @incollection{KralHaumer, author = {Kral, Christian and Haumer, Anton}, title = {Object Oriented Modeling of Rotating Electrical Machines}, series = {Advances in Computer Science and Engineering}, booktitle = {Advances in Computer Science and Engineering}, editor = {Schmidt, Matthias}, publisher = {IntechOpen}, isbn = {978-953-307-173-2}, doi = {10.5772/15898}, pages = {135 -- 160}, 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} } @article{SternerBauer, author = {Sterner, Michael and Bauer, Franz}, title = {Power-to-X im Kontext der Energiewende und des Klimaschutzes in Deutschland}, series = {Chemie-Ingenieur-Technik}, volume = {92}, journal = {Chemie-Ingenieur-Technik}, number = {1-2}, publisher = {Wiley}, issn = {0009-286X}, doi = {10.1002/cite.201900167}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-11669}, pages = {85 -- 90}, abstract = {Um den Einfluss verschiedener Power-to-X-Verfahren auf die Transformation des deutschen Energiesystems und das Erreichen der Klimaschutzziele zu {\"u}berpr{\"u}fen, wurde ein sektor{\"u}bergreifendes Energiesystemmodel entwickelt. Die daraus gewonnenen Ergebnisse zeigen: F{\"u}r eine erfolgreiche Energiewende ist der Einsatz von Power-to-X in Zukunft unverzichtbar. Vor allem in Bereichen und Sektoren, in denen hohe Energiedichten erforderlich und nur wenig andere Optionen zur Defossilisierung vorhanden sind, werden Power-to-X-Technologien zwingend notwendig.}, subject = {Power-to-Gas}, 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} } @inproceedings{SteiningerGadererDawoud, author = {Steininger, Peter and Gaderer, Matthias and Dawoud, Belal}, title = {Transient performance of a solar selective thermal insulation system}, series = {16th Advanced Building Skins Conference \& Expo, 21 - 22/10/2021, Bern, Switzerland}, booktitle = {16th Advanced Building Skins Conference \& Expo, 21 - 22/10/2021, Bern, Switzerland}, publisher = {Advanced Buidling Skins GmbH}, abstract = {A prototype of a thermal insulation system to offer high selectivity of the solar gain regarding the solar incidence angle (SATIS) was applied to a typical solid brick masonry for existing buildings in Germany. Light conducting elements (LCEs) inclined at 19 ° were incorporated in SATIS, which equals the average solar noon angle in southern Germany during winter. The entire wall construction was experimentally investigated in a differential climatic chamber test bench at four different irradiation angles according to a dynamic test procedure. In addition, a conventional wall construction (CWC) has been measured. At SATIS' design angle of 19 °, the SATIS wall construction shows a solar gain (SG) of 394.5 Wh/m², while the SG of the CWC amounts to only 25.4 Wh/m². The validated transient model of the SATIS wall construction showed that, at the end of the irradiation period of the dynamic test procedure (8 h), the solar heat penetrates to a depth of 253 mm and 111 mm inside the 385 mm thick brick wall masonry at the irradiation angles of 19 ° and 50 °, respectively. During the same time, the stored solar energy at 50 ° amounts to only 24.4 \% of that stored at 19 °.}, 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{KralHaumerKapelleretal., author = {Kral, Christian and Haumer, Anton and Kapeller, Hansj{\"o}rg and Pirker, Franz}, title = {Design and Thermal Simulation of Induction Machines for Traction in Electric and Hybrid Electric Vehicles}, series = {World Electric Vehicle Journal}, volume = {1}, journal = {World Electric Vehicle Journal}, number = {1}, publisher = {MDPI}, issn = {2032-6653}, doi = {10.3390/wevj1010190}, pages = {190 -- 196}, abstract = {An electric traction machine for an electric or a hybrid electric vehicle is usually designed for a specific operating point or cycle. For such an operating point or cycle, the masses and the cooling circuit of the electric machine determine the time dependent temperature distribution within the machine. For a specific load cycle, the thermal simulation of the machine can reveal possible mass and size reductions for a given insulation class of the machine. In addition, such simulations allow the comparison of various cooling concepts. In the machine design process, the first step is a conventional electromagnetic machine design. From the geometric data of this design and the material properties, the parameters of a thermal equivalent circuit can be derived. The differential and algebraic equations of the thermal equivalent circuit are solved by a simulation tool to predict the temperatures of the critical parts in the electric machine. A thermal equivalent circuit is accurate enough to predict the thermal behavior of the critical parts in the electric machine, and yet not too complex, to obtain simulation results with moderate numerical effort. This enables an iterative design process to optimize the drive.}, language = {en} } @article{CornetStadlerKongetal., author = {Cornet, Henriette and Stadler, Sebastian and Kong, Penny and Marinkovic, Goran and Frenkler, Fritz and Sathikh, Peer Mohideen}, title = {User-centred design of autonomous mobility for public transportation in Singapore}, series = {Transportation Research Procedia}, volume = {41}, journal = {Transportation Research Procedia}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2352-1465}, doi = {10.1016/j.trpro.2019.09.038}, pages = {191 -- 203}, abstract = {The paper presents a set of methods for user-centred design of autonomous mobility for public transportation in the context of a multi-disciplinary research programme in Singapore, called TUMCREATE. While traffic engineers plan the operation of the new mobility system, the Industrial Designers of TUMCREATE take on the role of designing the autonomous vehicles (AVs) and infrastructure for greater comfort and a positive travel experience for users. Tasks have been identified to promote user acceptance and facilitate the operation of autonomously driven vehicles for public transport. To fulfil these tasks, conventional design methods have been enhanced with Virtual Reality (VR) technology and with simulations developed by the computer scientists of TUMCREATE. Since public transportation is a complex and broad area, it cannot be investigated with a single design method. First results showed that conventional methods that consider the Universal Design principles guarantee the accessibility, usability and understandability of AVs and stations. VR has been identified as a suitable tool for Industrial Designers to evaluate communication concepts between AVs and pedestrians. This confirms that digital tools (i.e. VR) enhance conventional design methods, especially with regard to technologies that are not available on the market yet (e.g. AVs)}, 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{KeinerWalterBogdanovetal., author = {Keiner, Dominik and Walter, Lukas and Bogdanov, Dmitrii and Peters, Ian Marius and Breyer, Christian}, title = {Assessing the impact of bifacial solar photovoltaics on future power systems based on capacity-density-optimised power plant yield modelling}, series = {Solar Energy}, volume = {295}, journal = {Solar Energy}, publisher = {Elsevier}, doi = {10.1016/j.solener.2025.113543}, pages = {35}, abstract = {Bifacial solar photovoltaic (PV) technology is currently taking over the solar PV module market, exceeding a 90\% share in 2025. This important technology must be included in energy system modelling. This study provides a method for calculating the yield of monofacial and bifacial power plants in fixed-tilted, single-axis tracking, and east-west facing vertical setup. A novel method is introduced to maximise the capacity density of solar PV power plants without the need for detailed land cost for the most efficient use of the occupied area. The results indicate a 15-20\% yield gain from single-axis tracking compared to fixed-tilted power plants, and a limited bifacial gain of up to 10\% for most areas of the world. Higher bifacial gains are sporadically possible in specific conditions. Fixed-tilted systems show higher bifacial gains. Optimising tilt angles and row pitch would allow for 147 MW/ km2 capacity density today, though on average 70-110 MW/km2 can be achieved for 20.2\% module efficiency. The impact on the power system, studied in a free cost optimisation scenario and forcing vertical bifacial PV scenario, implying agrivoltaics, is not significant with a +/- 10\% change in total solar PV capacity, change in installed wind power of on average-10\%, increase of installed battery capacity of on average 5\%, and an on average changed levelised cost of electricity of-2\% globally. Bifacial solar PV technology has been found to be beneficial but no game changer for future power systems; system improvements are widely possible underlining the important role of this technology.}, language = {en} } @article{DoepfertCandasKrausetal., author = {Doepfert, Markus and Candas, Soner and Kraus, Hermann and Tzscheutschler, Peter and Hamacher, Thomas}, title = {Assessing the techno-economic benefits of LEMs for different grid topologies and prosumer shares}, series = {iScience}, volume = {28}, journal = {iScience}, number = {6}, publisher = {Elsevier - Cell Press}, doi = {10.1016/j.isci.2025.112493}, abstract = {The shift toward decentralized and renewable energy sources has introduced significant challenges to traditional power systems, necessitating innovative market designs. Local energy markets present a viable solution for integrating distributed energy resources such as photovoltaic systems, electric vehicles, and heat pumps. This study investigates the techno-economic implications of local energy markets compared to conventional market designs, focusing on their impact on average energy prices and operational peak power. Through comprehensive simulations across various grid topologies with varying penetration levels of the distributed energy resources, totaling 400 simulation setups, we demonstrate that local energy markets can enhance economic efficiency and grid stability with 99\% of the scenarios boasting lower average energy prices and 80\% lower operational peak power levels. The findings suggest that local energy markets can play a role in the future energy system, provided that additional infrastructure, management costs, and bureaucratic complexity are kept to a minimum.}, language = {en} } @article{ThemaBauerSterner, author = {Thema, Martin and Bauer, Franz and Sterner, Michael}, title = {Power-to-Gas: Electrolysis and methanation status review}, series = {Renewable and Sustainable Energy Reviews}, volume = {112}, journal = {Renewable and Sustainable Energy Reviews}, number = {7}, publisher = {Elsevier}, doi = {10.1016/j.rser.2019.06.030}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-26238}, pages = {775 -- 787}, abstract = {This review gives a worldwide overview on Power-to-Gas projects producing hydrogen or renewable substitute natural gas focusing projects in central Europe. It deepens and completes the content of previous reviews by including hitherto unreviewed projects and by combining project names with details such as plant location. It is based on data from 153 completed, recent and planned projects since 1988 which were evaluated with regards to plant allocation, installed power development, plant size, shares and amounts of hydrogen or substitute natural gas producing examinations and product utilization phases. Cost development for electrolysis and carbon dioxide methanation was analyzed and a projection until 2030 is given with an outlook to 2050. The results show substantial cost reductions for electrolysis as well as for methanation during the recent years and a further price decline to less than 500 euro per kilowatt electric power input for both technologies until 2050 is estimated if cost projection follows the current trend. Most of the projects examined are located in Germany, Denmark, the United States of America and Canada. Following an exponential global trend to increase installed power, today's Power-to-Gas applications are operated at about 39 megawatt. Hydrogen and substitute natural gas were investigated on equal terms concerning the number of projects.}, language = {en} } @article{SternerHofrichterMeisingeretal., author = {Sterner, Michael and Hofrichter, Andreas and Meisinger, Alexander and Bauer, Franz and Pinkwart, Karsten and Maletzko, Annabelle and Dittmar, Felix and Cremers, Carsten}, title = {19 Import options for green hydrogen and derivatives - An overview of efficiencies and technology readiness levels}, series = {International Journal of Hydrogen Energy}, volume = {90}, journal = {International Journal of Hydrogen Energy}, publisher = {Elsevier}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2024.10.045}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-77756}, pages = {1112 -- 1127}, abstract = {The import of hydrogen and derivatives forms part of many national strategies and is fundamental to achieving climate protection targets. This paper provides an overview and technical comparison of import pathways for hydrogen and derivatives in terms of efficiency, technological maturity and development and construction times with a focus on the period up to 2030. The import of hydrogen via pipeline has the highest system efficiency at 57-67 \% and the highest technological maturity with a technology readiness level (TRL) of 8-9. The import of ammonia and methanol via ship and of SNG via pipeline shows efficiencies in the range of 39-64 \% and a technological maturity of TRL 7 to 9 when using point sources. Liquid hydrogen, LOHC and Fischer-Tropsch products have the lowest efficiency and TRL in comparison. The use of direct air capture (DAC) reduces efficiency and TRL considerably. Reconversion of the derivatives to hydrogen is also associated with high losses and is not achievable for all technologies on an industrial scale up to 2030. In the short to medium term, import routes for derivatives that can utilise existing infrastructures and mature technologies are the most promising for imports. In the long term, the most promising option is hydrogen via pipelines.}, 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} } @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} } @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} } @article{BelyaevaKramarenkoShamoninChamonine, author = {Belyaeva, Inna A. and Kramarenko, Elena Yu and Shamonin (Chamonine), Mikhail}, title = {Magnetodielectric effect in magnetoactive elastomers: Transient response and hysteresis}, series = {POLYMER}, volume = {127}, journal = {POLYMER}, publisher = {ELSEVIER}, doi = {10.1016/j.polymer.2017.08.056}, pages = {119 -- 128}, abstract = {Magnetodielectric properties of magnetoactive elastomers comprising micrometer-sized iron particles dispersed in compliant elastomer matrices are experimentally studied in stepwise time-varying dc magnetic fields. It is found that imposition of magnetic field significantly increases both the effective lossless permittivity of these composite materials as well as their effective conductivity. These magnetodielectric effects are more pronounced for larger concentrations of soft-magnetic filler particles and softer elastomer matrices. The largest observed relative change of the effective dielectric constant in the maximum magnetic field of 0.57 T is of the order of 1000\%. The largest observed absolute change of the loss tangent is approximately 0.8. The transient response of the magnetodielectric effect to a step magnetic-field excitation can be rather complex. It changes from a simple monotonic growth with time for small magnetic-field steps (<0.1 T) to a non-monotonic behavior with a significant rapidly appearing overshoot for large magnetic-field steps (>0.3 T). The settling time to the magnetic-field step excitation can reach roughly 1000 s and it depends on the applied magnetic field and sample composition. There is also significant hysteresis of the magnetodielectric effect on the externally applied magnetic field. These findings are attributed to the rearrangement of ferromagnetic filler particles in external magnetic fields. The results will be useful for understanding and predicting the transient behavior of magnetoactive elastomers in applications where the control magnetic field is time dependent. (C) 2017 Elsevier Ltd. All rights reserved.}, language = {en} } @incollection{SternerBauerCrotoginoetal., author = {Sterner, Michael and Bauer, Franz and Crotogino, Fritz and Eckert, Fabian and von Olshausen, Christian and Teichmann, Daniel and Thema, Martin}, title = {Chemical Energy Storage}, series = {Handbook of Energy Storage}, booktitle = {Handbook of Energy Storage}, editor = {Sterner, Michael and Stadler, Ingo}, publisher = {Springer}, address = {Berlin, Heidelberg}, isbn = {978-3-662-55503-3}, doi = {10.1007/978-3-662-55504-0_8}, pages = {325 -- 482}, abstract = {Purely electrical energy storage technologies are very efficient, however they are also very expensive and have the smallest capacities. Electrochemical-energy storage reaches higher capacities at smaller costs, but at the expense of efficiency. This pattern continues in a similar way for chemical-energy storage. In terms of capacities, the limits of batteries (accumulators) are reached when low-loss long-term storage is of need. Chemical-energy storage and stocking fulfills these requirements completely. The storing itself may be subject to significant efficiency losses, but, from today's point of view and in combination with the existing gas and fuel infrastructure, it is the only national option with regards to the long-term storage of renewable energies. Chemical-energy storage is the backbone of today's conventional energy supply. Solid (wood and coal), liquid (mineral oil), and gaseous (natural gas) energy carriers are 'energy storages' themselves, and are stored using different technologies. In the course of energy transition, chemical-energy storage will be of significant importance, mainly as long-term storage for the power sector, but also in the form of combustibles and fuels for transport and heat. Not only are conventional storing technologies discussed within this chapter, but a detailed explanation is also given about the storage of renewable energies in the form of gaseous (power-to-gas, PtG) and liquid (power-to-liquid, PtL) energy carriers for electricity, heat, chemicals, and in the form of synthetic fuels.}, language = {en} } @article{SorokinBelyaevaShamoninChamonineetal., author = {Sorokin, Vladislav V. and Belyaeva, Inna A. and Shamonin (Chamonine), Mikhail and Kramarenko, Elena Yu}, title = {Magnetorheological response of highly filled magnetoactive elastomers from perspective of mechanical energy density: Fractal aggregates above the nanometer scale?}, series = {Physical Review E}, volume = {95}, journal = {Physical Review E}, number = {6}, publisher = {Amer Physical Soc}, doi = {10.1103/PhysRevE.95.062501}, abstract = {The dynamic shear modulus of magnetoactive elastomers containing 70 and 80 mass \% of carbonyl iron microparticles is measured as a function of strain amplitude via dynamic torsion oscillations in various magnetic fields. The results are presented in terms of the mechanical energy density and considered in the framework of the conventional Kraus model. The form exponent of the Kraus model is further related to a physical model of Huber et al. [Huber et al., J. Phys.: Condens. Matter 8, 409 (1996)] that uses a realistic representation for the cluster network possessing fractal structure. Two mechanical loading regimes are identified. At small strain amplitudes the exponent beta of the Kraus model changes in an externally applied magnetic field due to rearrangement of ferromagnetic-filler particles, while at large strain amplitudes, the exponent beta seems to be independent of the magnetic field. The critical mechanical energy characterizing the transition between these two regimes grows with the increasing magnetic field. Similarities between agglomeration and deagglomeration of magnetic filler under simultaneously applied magnetic field and mechanical shear and the concept of jamming transition are discussed. It is proposed that the magnetic field should be considered as an additional parameter to the jamming phase diagram of rubbers filled with magnetic particles.}, language = {en} } @incollection{StadlerBauerBudtetal., author = {Stadler, Ingo and Bauer, Franz and Budt, Marcus and Heindl, Eduard and Wolf, Daniel}, title = {Mechanical Energy Storage}, series = {Handbook of Energy Storage}, booktitle = {Handbook of Energy Storage}, editor = {Sterner, Michael and Stadler, Ingo}, publisher = {Springer Berlin Heidelberg}, address = {Berlin, Heidelberg}, isbn = {978-3-662-55503-3}, doi = {10.1007/978-3-662-55504-0_9}, pages = {483 -- 561}, abstract = {Chemical-energy storage systems use caverns, porous storage facilities, tanks, and storage rooms to store chemical energy sources. Caverns, caves, and reservoirs can also be used to store gaseous media such as air, liquid media such as water, and solid media such as rock. The principles of mechanical energy storage are based on classical Newtonian mechanics, or in other words on fundamental physics from the eighteenth and nineteenth centuries. As a result, these types of storage are typically divided into two categories; storage of kinetic and potential energy, or storage of 'pressure energy'. In this chapter, storage media is categorized by its aggregate state, and described by its function and application: first compressed air energy storage and then conventional electricity storage—pumped-storage plants. The chapter continues with a discussion of innovative methods of storing potential energy using water as a medium. These include artificially constructed pumped storage, pumped storage in the open sea, dam storage on rivers, pumped storage on heaps in repurposed mining areas, underfloor or underground pumped storage, and surface mine storage. The chapter concludes with a description of classical and modern flywheel energy storage systems. This age-old technology is then compared with a new concept: mechanical stored energy exploiting both pumped storage and change in the potential energy of rocks or large boulders.}, language = {en} } @article{BelyaevaKleppLemmeletal., author = {Belyaeva, Inna A. and Klepp, J{\"u}rgen and Lemmel, Hartmut and Shamonin (Chamonine), Mikhail}, title = {Feasibility of Probing the Filler Restructuring in Magnetoactive Elastomers by Ultra-Small-Angle Neutron Scattering}, series = {Applied Sciences}, volume = {11}, journal = {Applied Sciences}, number = {10}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/app11104470}, pages = {1 -- 9}, abstract = {Ultra-small-angle neutron scattering (USANS) experiments are reported on isotropic magnetoactive elastomer (MAE) samples with different concentrations of micrometer-sized iron particles in the presence of an in-plane magnetic field up to 350 mT. The effect of the magnetic field on the scattering curves is observed in the scattering vector range between 2.5 x 10(-5) and 1.85 x 10(-4) angstrom(-1). It is found that the neutron scattering depends on the magnetization history (hysteresis). The relation of the observed changes to the magnetic-field-induced restructuring of the filler particles is discussed. The perspectives of employing USANS for investigations of the internal microstructure and its changes in magnetic field are considered.}, language = {en} } @incollection{SternerBauer, author = {Sterner, Michael and Bauer, Franz}, title = {Definition and Classification of Energy Storage Systems}, series = {Handbook of Energy Storage}, booktitle = {Handbook of Energy Storage}, editor = {Sterner, Michael and Stadler, Ingo}, publisher = {Springer}, address = {Berlin, Heidelberg}, isbn = {978-3-662-55503-3}, doi = {10.1007/978-3-662-55504-0_2}, pages = {23 -- 47}, abstract = {Energy supply always requires energy storage—either as an intrinsic property or as additional system. It is an intrinsic property of solid, liquid, and gaseous fuels, although less so of water-borne heat, but not of electricity. So to meet variable demands and supplies, heat and electricity networks usually require additional storage systems. When they are added to an energy network, should they be viewed as 'suppliers' or as 'consumers'? Who is responsible for covering the costs of storage systems? To categorize storage systems in the energy sector, they first need to be carefully defined. This chapter defines storage as well as storage systems, describes their use, and then classifies storage systems according to temporal, spatial, physical, energy-related, and economic criteria.}, language = {de} } @misc{ThemaBauerSterner, author = {Thema, Martin and Bauer, Franz and Sterner, Michael}, title = {Power-to-Gas world status report}, series = {International Renewable Energy Storage Conference, D{\"u}sseldorf 14.-16.03.2019}, journal = {International Renewable Energy Storage Conference, D{\"u}sseldorf 14.-16.03.2019}, language = {de} } @incollection{SternerBauerCrotoginoetal., author = {Sterner, Michael and Bauer, Franz and Crotogino, Fritz and Eckert, Fabian and von Olshausen, Christian and Teichmann, Daniel and Thema, Martin}, title = {Chemische Energiespeicher}, series = {Energiespeicher - Bedarf, Technologien, Integration}, booktitle = {Energiespeicher - Bedarf, Technologien, Integration}, edition = {2. Auflage}, publisher = {Springer Vieweg}, address = {Berlin ; Heidelberg}, isbn = {978-3-662-48893-5}, doi = {10.1007/978-3-662-48893-5_8}, pages = {327 -- 493}, subject = {Energiespeicher}, language = {de} } @incollection{StadlerBauerBudtetal., author = {Stadler, Ingo and Bauer, Franz and Budt, Marcus and Heindl, Eduard and Wolf, Daniel}, title = {Mechanische Energiespeicher}, series = {Energiespeicher - Bedarf, Technologien, Integration}, booktitle = {Energiespeicher - Bedarf, Technologien, Integration}, edition = {2. Auflage}, publisher = {Springer Vieweg}, address = {Berlin ; Heidelberg}, isbn = {978-3-662-48893-5}, doi = {10.1007/978-3-662-48893-5_9}, pages = {495 -- 577}, language = {de} } @incollection{SternerBauer, author = {Sterner, Michael and Bauer, Franz}, title = {Definition und Klassifizierung von Energiespeichern}, series = {Energiespeicher - Bedarf, Technologien, Integration}, booktitle = {Energiespeicher - Bedarf, Technologien, Integration}, edition = {2. Auflage}, publisher = {Springer Vieweg}, address = {Berlin ; Heidelberg}, isbn = {978-3-662-48892-8}, doi = {10.1007/978-3-662-48893-5_2}, pages = {25 -- 49}, subject = {Energiespeicher}, language = {de} } @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} } @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} } @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} } @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{KlenkGalka, author = {Klenk, Eva Marianne and Galka, Stefan}, title = {Analysis of real-time tour building and scheduling strategies for in-plant milk-run systems with volatile transportation demand}, series = {IFAC - PapersOnLine}, volume = {52}, journal = {IFAC - PapersOnLine}, number = {13}, publisher = {Elsevier}, doi = {10.1016/j.ifacol.2019.11.517}, pages = {2110 -- 2115}, abstract = {In modern manufacturing systems, milk run (MR) systems represent route-based, cyclic material-handling systems that are used widely and enable frequent deliveries of containerized parts in small lot sizes from a central storage area to multiple points of use on the factory floor. Usually, deliveries take place at predetermined, constant time intervals. As in real-world MR systems, the number of containers to deliver in each interval varies in the short term, peaks in the number of deliveries may lead to capacity bottlenecks and late deliveries. In this paper, we develop three alternative strategies to determine starting times of MR cycles in real-time based on the current number of delivery orders in the system aiming to better handle variations in the number of orders. We evaluate the three strategies for different system load scenarios with respect to delivery service levels, order lead times, systems utilization and necessary number of MR trains using a discrete-event simulation model.}, language = {en} } @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{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} } @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. 3. Roadmap des Kopernikus-Projektes P2X, Phase II}, booktitle = {Optionen f{\"u}r ein nachhaltiges Energiesystem mit Power-to-X-Technologien: Transformation - Anwendungen - Potentiale. 3. Roadmap des Kopernikus-Projektes P2X, Phase II}, editor = {Ausfelder, Florian and Dura, Hanna Ewy}, publisher = {DECHEMA Gesellschaft f{\"u}r Chemische Technik und Biotechnologie e.V.}, address = {Frankfurt a.M.}, isbn = {978-3-89746-236-6}, pages = {19 -- 33}, language = {de} } @article{DahmenBogenbergerWeikl, author = {Dahmen, Victoria and Bogenberger, Klaus and Weikl, Simone}, title = {Modellierung des Verkehrsmittelwahlverhaltens mittels erkl{\"a}rbarem Maschinellem Lernen}, series = {Straßenverkehrstechnik}, volume = {69}, journal = {Straßenverkehrstechnik}, number = {2}, publisher = {Kirschbaum}, issn = {0039-2219}, doi = {10.53184/SVT2-2025-3}, pages = {96 -- 102}, abstract = {Die Modellierung der Verkehrsmittelwahl ist f{\"u}r die Vorhersage und das Verst{\"a}ndnis des Mobilit{\"a}tsverhaltens unerl{\"a}sslich. Hierbei wurden in den letzten Jahren mit maschinellem Lernen vielversprechende Ergebnisse erzielt, insbesondere f{\"u}r XGBoost- und Random-Forest-Modelle. Aufgrund der zunehmenden Verwendung von Tracking-basierten Smartphone-Apps zur Aufzeichnung des Mobilit{\"a}tsverhaltens, wenden wir diese Modelle auf einen solchen Datensatz an. Zudem analysieren wir eingehend deren Interpretierbarkeit. Wir kommen zu dem Schluss, dass das XGBoost-Modell am leistungsst{\"a}rksten und dennoch erkl{\"a}rbar ist. Die von solchen Modellen gewonnenen Erkenntnisse k{\"o}nnen beispielsweise genutzt werden, um die Verkehrsmittelwahl f{\"u}r beliebige Quelle-Ziel-Paare vorherzusagen.}, language = {de} } @inproceedings{ReichelGerstnerSchilleretal., author = {Reichel, Tobias and Gerstner, Mathias and Schiller, Leo and Attenberger, Andreas and Hackenberg, Rudolf and Dološ, Klara}, title = {A forensic analysis of GNSS spoofing attacks on autonomous vehicles}, series = {Cloud Computing 2025 : The Sixteenth International Conference on Cloud Computing, GRIDs, and Virtualization, 06.-10. April 2025, Valencia}, booktitle = {Cloud Computing 2025 : The Sixteenth International Conference on Cloud Computing, GRIDs, and Virtualization, 06.-10. April 2025, Valencia}, organization = {IARIA}, isbn = {978-1-68558-258-6}, issn = {2308-4294}, pages = {32 -- 39}, abstract = {Global Navigation Satellite Systems (GNSSs) are essential for modern technology, enabling precise geographic positioning in aviation, maritime shipping, and automotive systems. In the future, their role will be even more critical for autonomous vehicles, which rely on accurate localization for navigation and decision-making. However, the increasing connectivity of autonomous vehicles exposes them to cyber threats, including GNSS spoofing attacks, which manipulate location data to mislead onboard systems. As reliance on GNSS grows, so does the risk posed by spoofing attacks, making it a critical security concern. This paper describes GNSS spoofing attacks on autonomous vehicles, focusing on their detection both during and after an attack. Furthermore, we analyze data storage strategies to facilitate effective forensic analysis. We highlight the importance of position, signal, and camera data, which should be preserved to ensure a comprehensive forensic investigation. Finally, we suggest a simulation setup that enables studying which data could be used for a forensic investigation. Additionally, we examine established data frameworks and decide whether they are suitable for detecting GNSS spoofing attacks.}, language = {en} } @article{LindnerPipaKarpenetal., author = {Lindner, Matthias and Pipa, Andrei V. and Karpen, Norbert and Hink, R{\"u}diger and Berndt, Dominik and Foest, R{\"u}diger and Bonaccurso, Elmar and Weichwald, Robert and Friedberger, Alois and Caspari, Ralf and Brandenburg, Ronny and Schreiner, Rupert}, title = {Icing Mitigation by MEMS-Fabricated Surface Dielectric Barrier Discharge}, series = {Applied Sciences}, volume = {11}, journal = {Applied Sciences}, number = {23}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/app112311106}, pages = {1 -- 17}, abstract = {Avoiding ice accumulation on aerodynamic components is of enormous importance to flight safety. Novel approaches utilizing surface dielectric barrier discharges (SDBDs) are expected to be more efficient and effective than conventional solutions for preventing ice accretion on aerodynamic components. In this work, the realization of SDBDs based on thin-film substrates by means of micro-electro-mechanical-systems (MEMS) technology is presented. The anti-icing performance of the MEMS SDBDs is presented and compared to SDBDs manufactured by printed circuit board (PCB) technology. It was observed that the 35 mu m thick electrodes of the PCB SDBDs favor surface icing with an initial accumulation of supercooled water droplets at the electrode impact edges. This effect was not observed for 0.3 mu m thick MEMS-fabricated electrodes indicating a clear advantage for MEMS-technology SDBDs for anti-icing applications. Titanium was identified as the most suitable material for MEMS electrodes. In addition, an optimization of the MEMS-SDBDs with respect to the dielectric materials as well as SDBD design is discussed.}, language = {en} } @techreport{SternerBauerHofrichteretal., author = {Sterner, Michael and Bauer, Franz and Hofrichter, Andreas and Heberl, Michael}, title = {Systemanalyse und -integration Power-to-X im Kontext von erneuerbarer Elektrizit{\"a}t als Prim{\"a}renergie (SPIKE)}, pages = {87}, abstract = {Durch das in Paris beschlossene Ziel, die globale mittlere Temperatur auf deutlich unter 2 Grad Celsius gegen{\"u}ber dem vorindustriellen Niveau zu begrenzen, ist ein Ausstieg aus der Nutzung fossiler Energietr{\"a}ger und Rohstoffe bis zum Jahr 2050 notwendig (WBGU 2016). Daher hat sich die Bundesregierung das Ziel gesetzt, bis zur Mitte des Jahrhunderts eine weitgehende Treibhausgasneutralit{\"a}t zu erreichen. Hierzu ist neben einer Steigerung der Energieeffizienz in allen Sektoren ein Ausbau erneuerbaren Energien notwendig. Dies beinhaltet haupts{\"a}chlich den Zubau von Wind- und Solarstromanlagen. Somit gewinnt die Sektorkopplung immer mehr an Bedeutung und wird in Zukunft eine tragende Rolle f{\"u}r die Defossilisierung des Energiesystems spielen (BMUB 2016). Als zentrales Element der Sektorkopplung gilt Strom, der {\"u}ber Power-to-X (PtX) sowohl energetisch im W{\"a}rme-, und Verkehrssektor als auch stofflich in der Industrie und vor allem im Chemiesektor eingesetzt werden kann (Ausfelder et al. 2018a). Im Rahmen des P2X-Vorhabens der Kopernikus Forschungsinitiative wird die Sektorkopplung durch die Umwandlung von Strom mittels elektrochemischer Prozesse in stoffliche Ressourcen wie Wasserstoff, Synthesegas oder Kohlenstoffmonoxid untersucht. Der Schwerpunkt liegt auf der Betrachtung der Kopplung von Strom und Verkehr sowie Strom und Chemie und der Untersuchung von Prozessen und Pfaden, die aus {\"o}kologischer, {\"o}konomischer und gesellschaftlicher Sicht vorteilhaft sind. Eine vergleichende Einordnung in den Gesamtkontext der Energiewende mit Abw{\"a}gung zahlreicher Alternativen und Konkurrenztechnologien ist dort allerdings nicht vorgesehen. Zudem werden einige relevante PtX-Technologien wie Power-to-Heat nicht betrachtet. Aus diesem Grund wurden in SPIKE erg{\"a}nzende PtX-Technologiepfade aus systemanalytischer Sicht untersucht. Dies sind Power-to-Heat (PtH) und Power-to-Gas (PtG) {\"u}ber Elektrolyse und optionaler anschließender Methanisierung sowie die Herstellung ausgew{\"a}hlter Pfade der strombasierten Herstellung von Produkten der energieintensiven Industrie. Ziel des Forschungsvorhabens war die Analyse von PtX-Technologien und Pfaden, deren vergleichende Einordnung im Gesamtkontext der Energiewende sowie die Unterst{\"u}tzung des P2X Roadmapping Prozesses und die Ableitung von Handlungsempfehlungen. Ein besonderer Schwerpunkt lag auf dem Einsatz von PtX im Industriesektor. F{\"u}r das Vorhaben wurden Arbeitspakete (AP) erstellt, die Untersuchungen zu Technologie, Potenzial, {\"O}konomie und {\"O}kologie von PtH (AP 1), PtG (AP 2), Power-to-Ammoniak, Power-to-Ethen und Power-to-Propen (AP 3) umfassten. Daraus wurde in AP 4 ein Systemvergleich mit Einordnung von PtX in die Energiewende durchgef{\"u}hrt. Auf dieser Basis und der Identifizierung regulatorischer Rahmenbedingungen f{\"u}r PtX (AP 5) wurde das deutsche Energiesystem samt PtX-Pfaden in einem Energiesystemmodell abgebildet (AP 6). Die Ergebnisse flossen in das Roadmapping ein (AP 7). Zudem erfolgte ein Austausch mit den Projektpartnern und das Verfassen wissenschaftlicher Abhandlungen (AP 8).}, language = {de} } @incollection{SternerBauerHofrichter, author = {Sterner, Michael and Bauer, Franz and Hofrichter, Andreas}, title = {Systemanalyse von Power-to-X-Pfaden - Ergebnisse des Satellitenprojektes "SPIKE"}, series = {Optionen f{\"u}r ein nachhaltiges Energiesystem mit Power-to-X Technologien : Nachhaltigkeitseffekte - Potenziale Entwicklungsm{\"o}glichkeiten; 2. Roadmap des Kopernikus-Projektes "Power-to-X": Flexible Nutzung erneuerbarer Ressourcen (P2X)}, booktitle = {Optionen f{\"u}r ein nachhaltiges Energiesystem mit Power-to-X Technologien : Nachhaltigkeitseffekte - Potenziale Entwicklungsm{\"o}glichkeiten; 2. Roadmap des Kopernikus-Projektes "Power-to-X": Flexible Nutzung erneuerbarer Ressourcen (P2X)}, editor = {Ausfelder, Florian and Dura, Hanna Ewy}, publisher = {DECHEMA Gesellschaft f{\"u}r Chemische Technik und Biotechnologie e.V}, address = {Frankfurt am Main}, isbn = {978-3-89746-218-2}, pages = {145 -- 153}, language = {de} } @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} } @article{HirschbergRillWeinfurter, author = {Hirschberg, Wolfgang and Rill, Georg and Weinfurter, H.}, title = {Tire model TMeasy}, series = {Vehicle System Dynamics}, volume = {45}, journal = {Vehicle System Dynamics}, number = {sup1}, publisher = {Taylor\&Francis}, doi = {10.1080/00423110701776284}, pages = {101 -- 119}, abstract = {This paper describes the semi-physical tire model TMeasy for vehicle dynamics and handling analyses, as it was applied in the 'low frequency tire models' section of the research programme tire model performance test (TMPT). Despite more or less weak testing input data, the effort for the application of TMeasy remains limited due to its consequent 'easy to use' orientation. One particular feature of TMeasy is the wide physical meaning of its smart parameter set, which allows to sustain the identification process even under uncertain conditions. After a general introduction, the modelling concept of TMeasy is compactly described in this paper. Taking the standard tire interface (STI) to multibody simulation system (MBS) software into account, the way to apply TMeasy is briefly shown. This includes three selected examples of application. The final comments of the authors on TMPT describe the experiences and earnings received during the participation in that programme.}, language = {en} } @inproceedings{BaeumlHaumerKapelleretal., author = {B{\"a}uml, T. and Haumer, Anton and Kapeller, Hansj{\"o}rg and Starzinger, J. and Farzi, P.}, title = {Impact of inverter pulse inhibition on the high-voltage supply system of an electric vehicle — A simulative approach}, series = {2011 IEEE Vehicle Power and Propulsion Conference (VPPC 2011) : Powering sustainable transportation ; Chicago, Illinois, USA, 06. - 09.09.2011}, booktitle = {2011 IEEE Vehicle Power and Propulsion Conference (VPPC 2011) : Powering sustainable transportation ; Chicago, Illinois, USA, 06. - 09.09.2011}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-61284-248-6}, doi = {10.1109/VPPC.2011.6043159}, pages = {1 -- 5}, abstract = {This paper deals with a simulative approach for investigating the impact of inverter pulse inhibition during field weakening operation of permanent magnet synchronous machines and asynchronous induction machines. The modelling and simulation language Modelica is used to design models for the vehicle, the electric machine and the inverter in different abstraction levels. It is shown that when using a permanent magnet synchronous machine, a sudden breakdown of the field weakening current causes induction of high voltages in the stator windings. Hence, the electric system of the vehicle has to be protected against the resulting high currents. Furthermore precautions have to be taken to avoid dangerous driving conditions because of high braking torques in an inverter fault operation mode. In the case of the asynchronous induction machine an inverter pulse inhibition poses no big problem, neither for the electric system of the vehicle, nor the driver.}, language = {en} } @inproceedings{JungreuthmayerBaumlWinteretal., author = {Jungreuthmayer, C. and Bauml, T. and Winter, O. and Ganchev, M. and Kapeller, Hansj{\"o}rg and Haumer, Anton and Kral, Christian}, title = {Heat and fluid flow analysis of an internal permanent magnet synchronous machine by means of computational fluid dynamics}, series = {2011 IEEE International Electric Machines \& Drives Conference (IEMDC 2011) ; Niagara Falls, Ontario, Canada, 15 - 18 May 2011}, booktitle = {2011 IEEE International Electric Machines \& Drives Conference (IEMDC 2011) ; Niagara Falls, Ontario, Canada, 15 - 18 May 2011}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-4577-0060-6}, doi = {10.1109/IEMDC.2011.5994651}, pages = {515 -- 520}, abstract = {This paper presents a comprehensive computational fluid (CFD) model of a radial flux permanent magnet synchronous machine with interior magnets. In the CFD model the water jacket cooling and a simplified model of the topology of the distributed stator winding are considered. The heat sources of the CFD model are determined from a finite element analysis of the machine. The numerically determined temperature distributions of the machine are compared with measurement results from sensors located both in the stator and rotor. The particular focus of this paper is the analysis of the temperatures and the heat flow in the air gap and from the stator winding head and the rotor to the inner air.}, language = {en} }