@inproceedings{HinterreiterRauchBrueckl, author = {Hinterreiter, Marion and Rauch, Johannes and Br{\"u}ckl, Oliver}, title = {Long-term reactive power forecasting power grids - Challenges and methodologies}, series = {Applied Research Conference - ARC 04.07.2025, Augsburg}, booktitle = {Applied Research Conference - ARC 04.07.2025, Augsburg}, pages = {6}, abstract = {The transition of power systems 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. The growing integration of distributed energy resources (DERs), heat pumps (HPs), and electric vehicles (EVs) is particularly impacting lower voltage levels, which are evolving from traditionally consumer-dominated networks into active participants in energy dynamics. These developments have a significant influence on reactive power behavior, with many countries already reporting notable changes due to increased Q contributions from lower voltage levels. As bidirectional flows and decentralized generation increase, understanding and forecasting reactive power trends at these voltage levels becomes essential for ensuring grid stability and efficiency. This paper addresses the challenges of long-term Q forecasting in general by analyzing reactive power behavior in grids, the main influencing grid parameters and introducing existing approaches and concepts, analyzing their applicability, and discussing the associated challenges and methodologies. By shedding light on this underexplored area, the study aims to contribute to the development of advanced long-term reactive power forecasting methods and highlighting research trends.}, language = {en} } @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} } @inproceedings{HinterreiterBruecklRauch, author = {Hinterreiter, Marion and Br{\"u}ckl, Oliver and Rauch, Johannes}, title = {Methodology for long-term reactive power forecasts of medium-voltage grids}, series = {NEIS 2025 : Conference on Sustainable Energy Supply and Energy Storage Systems, Hamburg, September 15 - 16, 2025}, booktitle = {NEIS 2025 : Conference on Sustainable Energy Supply and Energy Storage Systems, Hamburg, September 15 - 16, 2025}, editor = {Schulz, Detlef}, publisher = {VDE Verlag}, isbn = {978-3-8007-6633-8}, pages = {218 -- 223}, abstract = {Understanding and assessing the long-term behavior of reactive power is crucial for power system planning and invest-ment decisions. This is particularly growing relevant for the lower voltage-grid levels, which are gaining importance due to significant changes in grid behavior, operational strategies, energy generation and consumption patterns. Currently, standardized methodologies for forecasting reactive power in medium-voltage grids are lacking, creating a gap in research and practical applications. To optimize grid investments and expansions, informed decisions based on reliable research and accurate forecasts are essential. This paper presents a methodology for long-term reactive power forecasting in me-dium-voltage grids, introducing a new approach to account for low- and medium-voltage grid interactions while address-ing common challenges like limited available grid data and scenario framework definition. The aim of the forecast is the future reactive power behaviour of a medium-voltage-grid at the high-voltage side of the high-voltage to medium-voltage transformer. The medium-voltage-level is modelled using a grid model approach, while low-voltage grids are being mod-elled using generic distribution grids. A 209-bus medium-voltage-grid model is used as an application example and to provide two exemplary use cases for a reactive power forecast for 2045.}, language = {en} } @inproceedings{StadlerKrausBrueckl, author = {Stadler, Andreas and Kraus, Hermann and Br{\"u}ckl, Oliver}, title = {Proposing an Optimization Model for a techno-economic Evaluation of Energy Storage 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}, isbn = {978-3-8007-6656-7}, pages = {97 -- 102}, abstract = {During the global energy crisis in 2022, electricity prices increased drastically. This lead, together with an overall higher price volatility to possibly higher electrical energy storage system (ESS) profitability. To test if the investment in an ESS can now be more profitable, an approach for a techno-economic evaluation of ESS is presented in this paper, using an optimization algorithm to determine the optimal way of covering a load flow profile with electricity trading products on the electricity market with and without the use of an energy storage system. The cost differences between using or not using the storage system are assumed to be the profits of the ESS, which must exceed the (interest-bearing) investment costs over its lifetime. The correct way of operation of the optimization model is validated and several storage sizes and capacities as well as several years of the electricity market data was analyzed, once with a perfect forecast of all prices of the electricity trading products and once with a forecast based on the previous years purchasing strategy. The results show that, using the prognosis and a 2 \% p.a. interest rate, only the storage combinations for 2.5 MWh/ 2.5 MW and 1 MWh/ 1 MW show profitability in 2023, whereas 2017 and 2020 show no profitability.}, language = {en} } @inproceedings{UhlSchamelAchhammeretal., author = {Uhl, Julius and Schamel, Marco and Achhammer, Anton and Sterner, Michael}, title = {Sustainable Steel Production in the Desert: Economic and Technical Assessment of a Hydrogen-Powered Steel Plant in Mauritania}, series = {2025 IEEE PES/IAS PowerAfrica, 28 September - 02 October 2025, Cairo}, booktitle = {2025 IEEE PES/IAS PowerAfrica, 28 September - 02 October 2025, Cairo}, publisher = {IEEE}, doi = {10.1109/PowerAfrica65840.2025.11289120}, pages = {6}, abstract = {The global steel industry is a major contributor to climate change and faces challenges in achieving a carbon-neutral production, hinging on the availability of cost-effective hydrogen produced by renewable energy. Mauritania, with its exceptional solar and wind resources, offers some of the most competitive conditions globally for hydrogen production. Instead of focusing on hydrogen exports, this study explores the technical feasibility and economic viability of establishing a renewable-powered steel plant in Mauritania, utilizing the country's abundant iron ore reserves. The findings suggest that sustainably produced steel in Mauritania could be cost-competitive with current European prices. With ongoing declines in investment costs for emerging renewable technologies, Mauritania has the potential to become one of the world's most cost-effective steel producers.}, language = {en} } @article{SchiekSolntsevNeshev2025, author = {Schiek, Roland and Solntsev, Alexander S. and Neshev, Dragomir N.}, title = {Measurement of the cubic nonlinear susceptibility in lithium niobate}, series = {Optical Materials Express}, volume = {15}, journal = {Optical Materials Express}, number = {5}, publisher = {Optica Publishing Group}, issn = {2159-3930}, doi = {10.1364/OME.557516}, pages = {1100 -- 1117}, year = {2025}, abstract = {We measured the cubic nonlinear susceptibility tensor elements ( χ(3)) for polarization along the primary crystallographic axis in titanium-indiffused lithium niobate waveguides, assessed through self-phase modulation using picosecond-duration pulses at telecommunication wavelengths. A dominant, highly temperature- and wavelength-dependent contribution from a cascaded second-order nonlinearity is observed. Through careful extraction of the cascaded effect, we quantify the intrinsic third-order susceptibility tensor elements as χ(3) zzzz(ω; ω, ω, -ω) = (5.2 ± 1.3) × 10-21 m2 V2 and χ(3) xxxx(ω; ω, ω, -ω) = χ(3) yyyy(ω; ω, ω, -ω) = (3.6 ± 0.8) × 10-21 m2 V2 . These measurements underscore the substantial impact of the cascaded nonlinearity in enhancing the effective cubic nonlinearity in lithium niobate and offer precise values essential for the design of nonlinear photonic devices.}, language = {en} } @misc{GlavanBelyaevaShamoninChamonineetal., author = {Glavan, Gašper and Belyaeva, Inna A. and Shamonin (Chamonine), Mikhail and Ruwisch, Kevin and Wollschl{\"a}ger, Joachim}, title = {Magnetoelectric Response of Laminated Cantilevers Comprising a Magnetoactive Elastomer and a Piezoelectric Polymer, in Pulsed Uniform Magnetic Fields [Data set]}, doi = {10.5281/zenodo.14652152}, language = {en} } @misc{BirettSchummHofrichteretal., author = {Birett, Falk and Schumm, Leon and Hofrichter, Andreas and Heusgen, Valentin and Rahim, Stefan}, title = {Wasserstoffatlas Deutschland (Hydrogen Map) [Data set]}, doi = {10.5281/zenodo.13960465}, abstract = {Input files required for Hydrogen Map workflow in the project "Wasserstoffatlas Deutschland", funded by the BMBF.}, language = {en} } @misc{GlavanBelyaevaShamoninChamonine, author = {Glavan, Gašper and Belyaeva, Inna A. and Shamonin (Chamonine), Mikhail}, title = {Multiferroic Cantilevers Containing a Magnetoactive Elastomer: Magnetoelectric Response to Low-Frequency Magnetic Fields of Triangular and Sinusoidal Waveform [Data set]}, doi = {10.5281/zenodo.14651784}, language = {en} } @inproceedings{NadimpalliMaierStauferetal., author = {Nadimpalli, Vamsi Krishna and Maier, Robert and Staufer, Susanne and R{\"o}hrl, Simon and Ezer, Timur and Grabinger, Lisa and Hauser, Florian and Mottok, J{\"u}rgen}, title = {EXPERT SURVEYS TO REAL TIME ADAPTATION OF LEARNING PATHS}, series = {ICERI2025 Proceedings}, booktitle = {ICERI2025 Proceedings}, editor = {G{\´o}mez Chova, Luis and Gonz{\´a}lez Mart{\´i}nez, Chelo and Lees, Joanna}, publisher = {IATED}, doi = {10.21125/iceri.2025.1571}, pages = {5677 -- 5687}, abstract = {Learning management systems rely on adaptive algorithms that use learner preferences to personalize the instructional content in form of learning paths. However, these preferences are uncertain in nature, and change over time. The present solutions are either static or purely data-driven missing the dynamic adaption to changes in the preferences and infusion of pedagogical nuances respectively. This paper introduces an extended variant of Nestor, our Bayesian network engine that models personality traits, learning styles, and learning strategies. This extension overlays a lightweight rule-based mechanism whose "secret recipe'' lies in the infusion of expert-derived weights adapting learning paths dynamically whenever a learner selects new material in Moodle. To parameterise these rules, we conducted a structured survey with 12 hand-picked professors and researchers in educational science. Each expert responded to 4 demographic items and 12 item that are distributed across algorithm-overview, scenario-based, and example-based categories, thereby supplying the nuanced weightings that result the personalised recommendations. This hybrid system (Nestor plus the expert-infused rule layer) operated during the winter term of 2025. 18 students completed an end-of-term questionnaire. Although their learning gains were not recorded, the majority of respondents reported positive or neutral experiences with the dynamically adapted learning paths. The {Future work} will compare three engines: (i) the present dynamic, expert-infused rule layer on top of the static Bayesian network, (ii) purely data-driven machine-learning models that neglect expert weighting, and (iii) the original static-adaptation Bayesian network without rules. Analyses of log files, intermediate satisfaction surveys, and pre/post term surveys will clarify whether this on-the-fly adaptation and pedagogical nuance lead to measurable learning benefits.}, language = {en} } @inproceedings{SchafferEzerRoehrletal., author = {Schaffer, Josefa and Ezer, Timur and R{\"o}hrl, Simon and Hauser, Florian and Staufer, Susanne and Nadimpalli, Vamsi Krishna and Grabinger, Lisa and Antoni, Erika and Mottok, J{\"u}rgen}, title = {EYE TRACKING GLASSES IN EDUCATIONAL SETTINGS: GUIDELINES ON DATA QUALITY}, series = {ICERI2025 Proceedings}, booktitle = {ICERI2025 Proceedings}, editor = {G{\´o}mez Chova, Luis and Gonz{\´a}lez Mart{\´i}nez, Chelo and Lees, Joanna}, publisher = {IATED}, doi = {10.21125/iceri.2025.1419}, pages = {5027 -- 5038}, abstract = {Eye movement modeling examples, so-called EMME videos, are a valuable tool in education, helping learners better understand instructional content. Like conventional educational videos, EMME videos combine text, images, and voiceovers. However, they also display the instructor's or teacher's gaze, guiding learners attention to key elements. Although various approaches exist for creating EMME videos, there is currently no standardised guideline for ensuring gaze data quality. Eye tracking technology is essential to capture gaze behaviour, and in educational settings without a fixed computer monitor - such as when using blackboards or conducting live experiments - the usage of mobile eye tracking glasses is beneficial. An accuracy study is conducted using mobile eye tracking glasses to provide empirical guidance for the development of high-quality educational EMME videos and ensure that the instructor's or teacher's gaze is captured with high precision. The study uses the Tobii Pro Glasses 3 and involves a static and a dynamic setup with 34 participants. To gain insight into the effects of visual impairments on accuracy, we also include participants who wear contact lenses. In the static setup, participants are seated at a desk with a headrest and focus on a poster with nine fixation points. In the dynamic setup, participants are walking in a controlled half-circle around the poster while maintaining focus on its centre. Each setup is performed multiple times under varying lighting levels (300 lux, 700 lux) and distances between participant and poster (80 cm, 120 cm, 180 cm). This enables the simulation of diverse educational environments, including the possibility of a teacher's or instructor's movement. The study results will be evaluated regarding lighting conditions, the distance between the person wearing eye tracking glasses and the object, and possible influences of contact lenses. Based on these findings, favourable conditions for creating EMME videos in educational settings are collected, especially when working without a fixed computer monitor. The results address the outlined research gap by providing instructors and teachers with guidelines enabling them to produce high-quality educational EMME videos.}, language = {en} } @inproceedings{AlhulaibiFrauenschlaegerMottok, author = {Alhulaibi, Ayham and Frauenschl{\"a}ger, Tobias and Mottok, J{\"u}rgen}, title = {Towards Post-Quantum-Ready Automated Certificate Lifecycle Management in Operational Technology}, series = {SECURWARE 2025, The Nineteenth International Conference on Emerging Security Information, Systems and Technologies, 26.-30.10.2025, Barcelona}, booktitle = {SECURWARE 2025, The Nineteenth International Conference on Emerging Security Information, Systems and Technologies, 26.-30.10.2025, Barcelona}, publisher = {IARIA}, isbn = {978-1-68558-306-4}, pages = {112 -- 116}, abstract = {Operational Technology (OT) systems increasingly depend on robust and automated certificate lifecycle management to maintain secure operations across long device lifespans and constrained environments. As quantum-capable adversaries emerge, these systems must also support cryptographic agility and prepare for a seamless transition to Post-Quantum Cryptography (PQC). This work presents a crypto-agile, post-quantum-ready testbed architecture that extends existing standards, such as Enrollment over Secure Transport (EST) and Bootstrapping Remote Secure Key Infrastructure (BRSKI), to support hybrid certificates, hardware-based key storage, and protocol flexibility for device bootstrapping and certificate management. A work-in-progress prototype implementation demonstrates support for both traditional and PQC algorithms across device types. Planned evaluations target performance on constrained devices, PQC readiness, and compatibility with alternative protocols. The system lays a foundation for secure and standards-compliant certificate management in future-proof OT deployments.}, language = {en} } @inproceedings{SchamelAchhammerSchummetal., author = {Schamel, Marco and Achhammer, Anton and Schumm, Leon and Sterner, Michael}, title = {Harvesting Sustainability: Cost-competitiveness of Green Fertilizer Value Chains in Western Africa}, series = {Proceedings of the 2025 IEEE PES/IAS PowerAfrica Conference (PAC 2025): pioneering sustainable energy solutions for Africa's Future, 28.09-02.10 2025, Cairo, Egypt}, booktitle = {Proceedings of the 2025 IEEE PES/IAS PowerAfrica Conference (PAC 2025): pioneering sustainable energy solutions for Africa's Future, 28.09-02.10 2025, Cairo, Egypt}, publisher = {IEEE}, isbn = {979-8-3315-9850-1}, doi = {10.1109/PowerAfrica65840.2025.11289137}, pages = {6}, abstract = {The use of nitrogen fertilizers in Sub-Saharan Africa is low compared to other regions of the world, leading to inadequate crop yields. Furthermore, conventional production from fossil fuel-based ammonia is highly emissions-intensive, making decarbonization urgent. Local production using green hydrogen, sourced solely from solar energy, water, and air, could address both agricultural and climate challenges. This study focuses on Ghana, where nitrogen inputs are among the lowest globally. Using an open-source framework, we evaluate high-resolution production costs for sustainable ammonia and examine two decarbonized pathways: aqueous ammonia and urea. It is found that cost estimates with current assumptions mostly exceed historical prices. However, given their resilience to global market disruptions and expected future cost decreases of the technologies used, these sustainable approaches represent a promising pathway for development in Sub-Saharan Africa.}, language = {en} } @inproceedings{HopfenspergerVanselowHopkinsetal., author = {Hopfensperger, Bernhard and Vanselow, Marcel and Hopkins, Andrew and Hahn, Ingo}, title = {Investigation of the Effect of Magnetic Coupling on the Capacitor Current of Dual Three-Phase Permanent Magnet Synchronous Machine Drives}, series = {2025 Energy Conversion Congress \& Expo Europe (ECCE Europe); Birmingham, United Kingdom ; 9/1/2025 - 9/4/2025}, booktitle = {2025 Energy Conversion Congress \& Expo Europe (ECCE Europe); Birmingham, United Kingdom ; 9/1/2025 - 9/4/2025}, publisher = {IEEE}, isbn = {979-8-3315-6752-1}, doi = {10.1109/ECCE-Europe62795.2025.11238664}, pages = {6}, abstract = {The drive towards electrification of vehicles and transport systems has led to research into multiphase drive topologies beyond the conventional three. Dual three-phase machine drives are attractive due to reduced torque and DC-link harmonic content in addition to fault tolerance. Further DC-link rms-current reductions can be realised by applying appropriate modulation schemes and shifting/interleaving PWM patterns. However, the magnetic cross coupling between the two three-phase systems impacts the output current harmonics and subsequently the torque ripple which is further exacerbated by interleaving of their respective carriers. The impact of magnetic coupling on the DC-link and output current ripples is investigated.}, language = {en} } @inproceedings{HauserStauferRoehrletal., author = {Hauser, Florian and Staufer, Susanne and R{\"o}hrl, Simon and Nadimpalli, Vamsi Krishna and Ezer, Timur and Grabinger, Lisa and Mottok, J{\"u}rgen and Falter, Thomas}, title = {LEVERAGING FIVE QUESTIONNAIRES TO ANALYZE STUDENT LEARNING STRATEGIES AND GENERATE AI-POWERED INDIVIDUALIZED LEARNING PATHS}, series = {ICERI2025 Proceedings}, booktitle = {ICERI2025 Proceedings}, editor = {G{\´o}mez Chova, Luis and Gonz{\´a}lez Mart{\´i}nez, Chelo and Lees, Joanna}, publisher = {IATED}, doi = {10.21125/iceri.2025.0658}, pages = {1775 -- 1784}, abstract = {Background: The COVID-19 pandemic has significantly accelerated the shift toward online and blended learning in higher education, placing renewed emphasis on the individualization of learning content to meet diverse student needs. Even high-quality learning materials may fail to engage learners if they do not align with students' personal preferences and learning styles. Identifying these learner preferences, therefore, emerges as a critical challenge. Objectives: This paper presents ongoing work within a larger research project aimed at employing artificial intelligence to recommend optimal learning path for students in specific courses. Beyond mere optimization, the goal is to ensure the best possible fit between learning materials and individual learners. Sample \& Methods: A total of 27 students from technical degree programs took part in this survey. All participation was voluntary, and data were handled in full compliance with GDPR regulations. Although our broader project integrates fine-grained learning analytics from Moodle, the present abstract focuses exclusively on the self-report questionnaire results. Participants completed five instruments: 1. Index of Learning Styles (ILS) 2. LIST-K (Learning and Study Strategies Inventory - Short version) 3. BFI-10 (Big Five Inventory - 10 items) 4. Custom Preferences Instrument, capturing preferences for specific learning elements (e.g. instructional videos, lecture notes, summaries) and basic demographic data 5. Motivational Value Systems Questionnaire (MVSQ), piloted last semester to assess value orientations and motivational drivers Results: Preliminary analyses of the questionnaire data reveal: - Learning Styles (ILS): The majority lean toward the visual learning type (M = 5.740, SD = 3.430). - Learning Strategies (LIST-K): High scores on metacognitive strategies (M = 3.000; SD = 0.520) and collaboration with peers (M = 3.190; SD = 0.540). - Preferred Learning Elements: Summaries, overviews, and self-checks are most favored. - Value Orientations (MVSQ): Students are primarily driven by the pursuit of personal achievement (M = 4.400; SD = 11.140). Conclusion \& Significance: By integrating these five standardized questionnaires, we gain valuable insights into student learning preferences—insights that complement our Moodle analytics in the broader project. Observed trends suggest that learning materials should be concise and designed to facilitate peer interaction and knowledge deepening. These findings will guide the refinement of our AI-driven recommendation engine, enhancing its ability to deliver personalized learning paths that boost both engagement and effectiveness.}, language = {en} } @inproceedings{EzerRoehrlMottok, author = {Ezer, Timur and R{\"o}hrl, Simon and Mottok, J{\"u}rgen}, title = {Towards accurate eye tracking: quantifying error in linear pixel-to-degree conversion}, series = {ICERI2025 Proceedings}, booktitle = {ICERI2025 Proceedings}, editor = {G{\´o}mez Chova, Luis and Gonz{\´a}lez Mart{\´i}nez, Chelo and Lees, Joanna}, publisher = {IATED}, doi = {10.21125/iceri.2025.1841}, pages = {6709 -- 6717}, abstract = {Eye tracking has become a powerful tool for analyzing cognitive processes in educational research. Educators and researchers can utilize eye tracking to model learners by determining their gaze patterns. In addition, eye tracking can be used directly for teaching by extracting experts' gaze behavior in certain areas and learning from it. However, eye tracking data is captured in a variety of coordinate systems, which can differ across individual studies. Consequently, algorithms, such as eye movement classifiers, must frequently convert gaze data between different coordinate systems. In particular, the conversion from screen pixels into visual degrees is typically approximated by a linear conversion in current literature and standard practice. However, this approximation introduces inaccuracies, thus potentially obscuring eye movements relevant to educational research. This paper provides a detailed geometric and analytical examination of the commonly applied linear approximation, quantifying its error in comparison to the exact coordinate conversion from screen pixels to angular degrees. For this purpose, the exact conversion formulas are mathematically derived from geometric optics, enabling researchers and educators to use them in their work. Utilizing these derived transformations can improve the robustness of analyses, for example, when detecting subtle eye movements. The present work supports educational research using eye tracking to achieve more insightful findings that may have previously been obscured by measurement inaccuracies. Thereby, we provide an important contribution toward more reliable and valid research and educational practices in eye tracking.}, language = {en} } @inproceedings{BuglSchneiderSehr, author = {Bugl, Benedikt and Schneider, Viola I. and Sehr, Armin}, title = {Vertical Sound Localization: Precision and Robustness to Reverberation in a Large-Scale Study}, series = {Proceedings of the 11th Convention of the European Acoustics Association Forum Acusticum / EuroNoise 2025 // M{\´a}laga, Spain ; 23-26. June 2025}, booktitle = {Proceedings of the 11th Convention of the European Acoustics Association Forum Acusticum / EuroNoise 2025 // M{\´a}laga, Spain ; 23-26. June 2025}, publisher = {European Acoustics Association}, isbn = {978-84-87985-35-5}, doi = {10.61782/fa.2025.0953}, pages = {3431 -- 3434}, abstract = {Vertical sound localization, the ability to perceive the elevation of a sound source, is a fundamental aspect of human auditory perception, yet it remains far less understood than horizontal localization. Existing studies rely on small sample sizes, limiting the generalizability of findings. The presented study bridges that gap by examining vertical sound localization and precision in a cohort exceeding 150 participants, making it the largest investigation of its kind to date.Participants were exposed to broadband noise stimuli from various elevations under controlled anechoic conditions. The elevation localization error was measured by comparing perceived sound source elevations to actual positions of speakers of a curved array. Azimuth angles of arrival were altered between 0°, 45° and 90°. For a small group the experiment was repeated in echoic conditions, to gain insight in reverberation and reflection robustness of vertical sound localization.This large-scale study establishes benchmarks for vertical sound localization precision and robustness, advancing our understanding of human auditory spatial perception. These findings have implications for audio technology development, such as spatial audio rendering and hearing aid design, and lay the groundwork for further exploration into the neural and anatomical underpinnings of vertical localization.}, language = {en} } @inproceedings{StauferEzerRoehrletal., author = {Staufer, Susanne and Ezer, Timur and R{\"o}hrl, Simon and Grabinger, Lisa and Hauser, Florian and Nadimpalli, Vamsi Krishna and Antoni, Erika and Mottok, J{\"u}rgen and Schaffer, Josefa}, title = {TYCHE ALGORITHM 2.0: Learning Paths from Questionnaire Responses and Learning Analytics}, series = {ICERI2025 Proceedings}, booktitle = {ICERI2025 Proceedings}, publisher = {IATED}, isbn = {978-84-09-78706-7}, doi = {10.21125/iceri.2025.0831}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-87846}, pages = {2562 -- 2572}, abstract = {The digitalization of learning processes has increased the need for adaptive learning paths tailored individually to learners. A novel algorithm for learning path generation is presented in this paper, namely Tyche 2.0. It extends the original Tyche approach after Staufer et al. - a Markov model for generating learning paths - by integrating additional learner data beyond learning styles (Index of Learning Styles (ILS)), including learning strategies (LIST-K questionnaire), personality traits (BFI-10 questionnaire), and learning analytics captured through screen recordings. In order to be able to use the screen recordings, a heuristic evaluates them. Furthermore, this enhanced algorithm employs Markov models to dynamically generate personalized learning paths. These are based on both questionnaire responses and real-time engagement data, the weights of which undergo dynamic adjustment over time. We made a small evaluation of Tyche 2.0 without the learning analytics influence, which shows that there is room for further improvements. Future research will focus on evaluating whole Tyche 2.0 in another university setting to further improve personalization and user engagement.}, language = {en} } @misc{Schoen, type = {Master Thesis}, author = {Sch{\"o}n, Matthias}, title = {Implementation and Evaluation of the ESPRIT Algorithm for DoA Estimation on an FPGA-based SDR Platform}, address = {Regensburg}, doi = {10.35096/othr/pub-8688}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-86883}, school = {Ostbayerische Technische Hochschule Regensburg}, pages = {vi, 104}, abstract = {Environmental sensing using smart antennas and antenna arrays is a broad field with many applications in different areas. This thesis is part of the initial stage of a longer research project at the OTH Regensburg, with the goal of enhancing the antenna-array-based sensing capabilities of base stations. Existing technologies that utilize radio waves, such as radar, often require the generation of special signals to scan the environment. This project aims to utilize the existing mobile communication traffic instead, making the benefits of sensing capabilities available to a wider range of applications. Many of the array processing methods require high computational power and are used in environments with real-time constraints. Therefore, the use of field-programmable gate arrays (FPGAs) for hardware acceleration of these methods will be investigated, evaluating which methods are suitable for implementation on FPGAs. The focus in this thesis lies on the Estimation of Signal Parameters Via Rotational Invariance Techniques (ESPRIT) method for direction of arrival (DoA) estimation, as it is a popular and highly accurate method that does not rely on calibration. The accelerator is implemented for the RFSoC4x2 software-defined radio (SDR), using Vitis High-Level Synthesis (HLS) for implementation of the algorithm itself, Vivado for the hardware configuration, and Python Productivity on Zynq (PYNQ) for drivers and application code. Simulations for evaluation and verification, as well as test data generation, are implemented in Julia, using a custom array signal processing package. A measurement setup is used to collect experimental data for simulation and evaluation of the performance of the implemented ESPRIT. It is shown that the underlying assumption of equal subarrays does not hold for the array used for the measurements. This causes the estimates to be erroneous and can only be addressed by employing other algorithms that allow for the required calibration.}, subject = {Field programmable gate array}, language = {en} } @article{StrausKravanjaKriegletal., author = {Straus, Izidor and Kravanja, Gaia and Kriegl, Raphael and Shamonin (Chamonine), Mikhail and Drevenšek-Olenik, Irena and Jezeršek, Matija and Kokot, Gašper}, title = {Laser Micromachining for Polymer Surface Topography Designt}, series = {JoVE journal : engineering}, journal = {JoVE journal : engineering}, publisher = {JoVE}, doi = {10.3791/68126}, pages = {15}, abstract = {Soft magnetoactive elastomers (MAEs) are smart materials that respond to external magnetic fields by dynamically altering their mechanical properties. They are composed of magnetically responsive microparticles embedded within a soft polymer matrix, exhibiting an effective shear modulus of up to 100 kPa. In recent decades, MAEs' bulk properties have been successfully exploited for applications such as dynamic vibration damping, vibration sensing, and actuation in soft robotics. Recent research has shifted to their surface properties, revealing promising results on tunable surface features such as roughness, adhesion, and wetting. Even the transport of small solid and fluid objects was demonstrated. The associated surface effects can be significantly enhanced through the precise engineering of surface topography. In this article, an efficient laser micromachining technique, with a resolution of 15 µm, is presented, which enables rapid prototyping of MAE surfaces. It allows the creation of various complex shapes and offers functionality beyond the one achievable with traditional molding techniques. Additionally, the approach is versatile and can be applied to any polymer that sufficiently absorbs the laser light. As an example, a lamellar surface micro-pattern fabrication process and its characterization by optical and scanning electron microscopies are shown. Its response to a magnetic field is demonstrated. The technique provides a flexible and fast solution for optimizing polymer surface design across a wide range of applications.}, language = {en} } @inproceedings{HammerMottok, author = {Hammer, Pascal and Mottok, J{\"u}rgen}, title = {Prototyping for high-performance random number generators for critical systems}, series = {2025 International Conference on Applied Electronics (AE), 08-09. September 2025, Pilsen Czech Republic}, booktitle = {2025 International Conference on Applied Electronics (AE), 08-09. September 2025, Pilsen Czech Republic}, publisher = {IEEE}, doi = {10.1109/AE66163.2025.11197780}, pages = {7}, abstract = {The security of modern cryptographic applications depends on the quality of their random number generators (RNGs). While physical true random number generators (PTRNGs) provide high-quality randomness, their performance is often insufficient for high-throughput applications. On the other hand, deterministic random number generators (DRNGs) offer better speed but lack true randomness. This paper presents an approach to developing a high-performance PTRNG. The research focuses on optimizing the digitization of analog noise signals. For this purpose, an ADC was selected that can digitize analog signals at a high clock rate. The functionality of the ADC could be verified by digitizing reference signals. Preliminary results by digitizing the analog noise signal demonstrates the feasibility of the proposed approach, but highlight challenges in achieving good results for Min-Entropy.}, language = {en} } @inproceedings{MartererMuhrSoukupetal., author = {Marterer, Verena and Muhr, Franz-Xaver and Soukup, Radek and Hipp, Susanne and Blecha, Tom{\´a}š}, title = {Material characterization using waveguide measurement technique for the development of textile antennas}, series = {2025 19th European Conference on Antennas and Propagation (EuCAP); 30. March - 04. April 2025, Stockholm, Sweden}, booktitle = {2025 19th European Conference on Antennas and Propagation (EuCAP); 30. March - 04. April 2025, Stockholm, Sweden}, publisher = {IEEE}, isbn = {978-88-31299-10-7}, doi = {10.23919/EuCAP63536.2025.10999278}, pages = {5}, abstract = {Significant advances in using conductive textiles have been made over the past two decades, particularly in knitted fabrics. The aim is to deepen understanding of how knitted structures, especially those with hybrid yarns containing fine conductive elements (microwires), interact with electromagnetic fields. To establish simulation models that align with subsequent measurements, it is crucial to determine the dielectric properties, specifically relative permittivity and loss tangent/conductivity. This research investigates whether knitted structures with hybrid yarns exhibit anisotropic permittivity, meaning different dielectric properties along orthogonal axes within the fabric plane. These properties were measured using a waveguide technique, whereby the structures were rotated by 90° to observe changes. The results demonstrate that the knitted structure exhibits metallic-like reflective behavior in one direction, while rotation leads to dielectric material characteristics. This effect is influenced by the number of conductive microwires and the materials used for these wires, such as silver-plated copper or bronze.}, language = {en} } @inproceedings{MartererSoukupHippetal., author = {Marterer, Verena and Soukup, Radek and Hipp, Susanne and Blecha, Tom{\´a}š}, title = {Effective material approach for simulating knitted bowtie antennas}, series = {2025 6th International Conference in Electronic Engineering \& Information Technology (EEITE); 4-6 June 2025, Chania Greece}, booktitle = {2025 6th International Conference in Electronic Engineering \& Information Technology (EEITE); 4-6 June 2025, Chania Greece}, publisher = {IEEE}, isbn = {979-8-3315-4419-5}, doi = {10.1109/EEITE65381.2025.11165995}, pages = {6}, abstract = {Textile antennas offer a promising solution for the integration of communication and sensor functions into wearable systems. Their flexibility, lightweight and seamless compatibility with garments make them ideal for wearable technology and medical monitoring applications. This paper investigates the characterization and simulation of a bowtie antenna made from knitted textile structures with hybrid yarns. These yarns, which consist of metallic microwires combined with textile threads, exhibit unique electromagnetic properties. The aim is to create a comprehensive simulation model using the effective material approach to reduce computational complexity while maintaining accuracy. Compared to a full three-dimensional simulation of the knitted structure, the effective material approach significantly reduces computational time and effort. Practical measurements were carried out in the frequency range from 3.3 GHz to 4.9 GHz to determine the dielectric properties of the materials.}, language = {en} } @inproceedings{RaspSahinbasReisingeretal., author = {Rasp, Franziska and Sahinbas, Burak and Reisinger, Thomas and Leitgeb, Erich and Hipp, Susanne}, title = {Polarization-based peak distortion mitigation for 5G sidelink positioning}, series = {2025 International Conference on Software, Telecommunications and Computer Networks (SoftCOM), 18-20 September 2025, Split, Coratia}, booktitle = {2025 International Conference on Software, Telecommunications and Computer Networks (SoftCOM), 18-20 September 2025, Split, Coratia}, publisher = {IEEE}, address = {Split}, isbn = {978-953-290-143-6}, issn = {1847-358X}, pages = {6}, abstract = {For cooperative driving both environmental perception and communication with other vehicles and the infrastructure are essential to avoid safety critical situations. The 5G Sidelink, as part of the Cellular Vehicle to Everything framework, enables both communication and, since 3GPP Release 18, positioning for distance estimation between vehicles. Due to the expected bandwidth limitations of 5G Sidelink in the Intelligent Transportation System band, combined with signal distortion caused by multi-path superposition, achieving submeter positioning accuracy is a significant challenge. Polarization diversity is investigated as a potential approach to mitigate errors resulting from signal distortion and subsequent peak shifts due to multi-path superposition. This work investigates the potential for reduced peak shift errors through the use of dual-polarized receive antennas. The received signals are processed using a polarization scan algorithm and compared to the accuracy achieved with single-antenna systems. The analysis is conducted using the Quasi Deterministic Radio Channel Generator framework with statistical Vehicle-to-Everything channel models. Simulation results show that polarization scan-based postprocessing reduces peak shifts and improves robustness in scenarios with polarization-mismatched antenna configurations.}, language = {en} } @article{HeberlHofrichterRanketal., author = {Heberl, Michael and Hofrichter, Andreas and Rank, Daniel and Bauer, Franz and Sterner, Michael}, title = {Influence of plant dimensioning and location on the ecology of PEM electrolysis}, series = {International Journal of Hydrogen Energy}, volume = {167}, journal = {International Journal of Hydrogen Energy}, publisher = {Elsevier}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2025.151039}, pages = {11}, abstract = {PV and wind systems with PEM electrolysis offer great potential for producing hydrogen with low emissions. Our research has identified the ecologically optimal size of PEM in relation to fixed PV/wind capacities. We calculate efficiencies and production volumes for PEM with 240 capacity and site variations. We analyse the global warming potential of all systems and draw conclusions about the optimal system design. The lowest GWP is achieved at the site with the highest full load hours with 1.32 kg CO2-eq/kg H2 (Wind, 28 MW electrolysis) and 4.24 kg CO2-eq/kg H2 (PV, 23 MW electrolysis). We have identified a clear trend: increasing PV/wind full load hours leads to higher ideal PEM capacities. However, there is a significant discrepancy between the ideal economic and ecological capacity. Furthermore, higher electrolysis capacities can achieve lower emissions as they increasingly operate at a more efficient partial load.}, language = {en} } @inproceedings{FuhrmannNiemetz, author = {Fuhrmann, Thomas and Niemetz, Michael}, title = {Fostering democratic attitude within engineering education}, series = {11th International Conference on Higher Education Advances (HEAd'25)}, booktitle = {11th International Conference on Higher Education Advances (HEAd'25)}, publisher = {Editorial Universitat Polit{\`e}cnica de Val{\`e}ncia (edUPV)}, address = {Valencia}, doi = {10.4995/HEAd25.2025.20093}, pages = {879 -- 886}, abstract = {According to the education ideal advocated by Wilhelm von Humboldt, education should be a holistic process to develop the whole human being and should not be narrowed toward job training. For example, in democratic societies, education should be directed to fostering a democratic mindset of students to strengthen pluralistic democracy. It is always possible to introduce a general course into a study program that deals with democratic education from a theoretical point of view. But by introducing such a course, the time spent on technical subjects will be reduced. The other major disadvantage of such solutions is that democratic education is seen to be separated from technical education. But in the contrary, democracy should be included in the whole life as a general way of thinking and cooperation between individuals. Therefore, ideas and lecture experiences are presented in this article on how democratic education can be integrated into all engineering subjects as an elementary educational design concept. Students should be led toward a general democratic attitude by practical application. To achieve this, democratic learning environments can be established in all types of courses like lectures, seminars, and labs. This includes, for example, the design of exercises, the presentation of the theoretical content, and the interaction between professors and students as well as the interaction between the students themselves as induced by the teaching activities. Also in exams, elements to promote democratic thinking are possible: Exams should be not directed to learning only content but toward understanding, creativity, and problem-solving competence. They should include, where possible, the fact that correct technical solutions are not unique but that a multiverse of solutions exists, with each solution featuring various strengths and weaknesses. This not only sensitizes the students for the need for (e.g. socially or environmentally) responsible technical design choices but also allows them to find optimized solutions for the engineering challenges at hand. In sum, lecturers should be aware that a democratic learning environment is a demanding process, as students must be taken as serious partners in a joint learning process and surprises are to be expected.}, language = {en} } @article{SchummBrownAbdelKhaleketal., author = {Schumm, Leon and Brown, Tom and Abdel-Khalek, Hazem and Ueckerdt, Falko and Sterner, Michael and Fioriti, David and Parzen, Max}, title = {The impact of temporal hydrogen regulation on hydrogen exporters and their domestic energy transition}, series = {Nature Communications}, volume = {16}, journal = {Nature Communications}, publisher = {Nature}, address = {London}, doi = {10.1038/s41467-025-62873-w}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-84857}, pages = {13}, abstract = {As global demand for green hydrogen rises, potential hydrogen exporters move into the spotlight. While exports can bring countries revenue, large-scale on-grid hydrogen electrolysis for export can profoundly impact 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-benefits of domestic carbon dioxide mitigation and hydrogen exports, whereby exports can reduce market-based costs for domestic electricity consumers while mitigation reduces costs for hydrogen exporters. However, increasing hydrogen exports in a fossil-dominated system can substantially raise market-based costs for domestic electricity consumers, but surprisingly, temporal matching of hydrogen production can lower these costs by up to 31\% with minimal impact on exporters. Here, we show that 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} } @phdthesis{Grabinger, author = {Grabinger, Lisa}, title = {Data Science in der empirischen Eyetracking-Forschung}, doi = {10.35096/othr/pub-8479}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-84797}, school = {Ostbayerische Technische Hochschule Regensburg}, pages = {ix, 369 Seiten}, abstract = {Empirische Forschung stellt Anf{\"a}nger vor eine Vielzahl von Herausforderungen. Besonders herausfordernd gestaltet sich die (statistische) Datenanalyse -- eine Aufgabe, die bislang Vorkenntnisse aus zwei verschiedenen Bereichen erfordert: Experimentalforschung und Programmierung. Es muss bekannt sein, was zu tun ist, aber auch wie dies technisch umgesetzt werden kann. Die vorliegende Arbeit befasst sich mit der Frage, wie angehende Forschende bei dieser Aufgabe bestm{\"o}glich unterst{\"u}tzt werden k{\"o}nnen. In einem ersten Schritt wird hierf{\"u}r die Ausgangslage erfasst. Mit einer systematischen Literaturrecherche wird identifiziert, welche Analyseverfahren in der Praxis Anwendung finden; f{\"u}r diese Verfahren werden dann jeweils der theoretische Hintergrund und die praktische Anwendung aufgearbeitet. Zudem werden in unsystematischer Recherche die M{\"o}glichkeiten ausgelotet, die bestehende Software-Systeme bieten. Basierend darauf wird dann eine Webanwendung konzipiert bzw. realisiert, die g{\"a}ngige Analysen auf eine Weise erm{\"o}glicht, die sowohl f{\"u}r Statistik- als auch f{\"u}r Programmieranf{\"a}nger geeignet ist. Das entstandene System wird in einem dritten Schritt durch heuristische Diskussion und empirische Nutzerstudien best{\"a}tigt. Angemerkt sei, dass alle Untersuchungen auf die empirische Eyetracking-Forschung in der Disziplin Software Engineering zugeschnitten, aber nicht darauf beschr{\"a}nkt sind.}, language = {de} }