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Optimierung des Energiemanagements durch Aggregatoren
No full textIn der vorliegenden Arbeit wird ein gemischt-ganzzahliges lineares Optimierungsmodell zur Abbildung des Entscheidungsproblems von Energieaggregatoren (EAs) entwickelt, das die Einsatzplanung verschiedenartiger flexibler Energieressourcen, sowie das Handeln von Energie an verschiedenen Märkten für eine dem EA zugeordnete Menge von Haushalten beinhaltet. Der zentrale Forschungsbeitrag im Vergleich zu früheren Arbeiten in der Entwicklung des EA-Modells (EAM) liegt darin, dass es zum Einen einen ganzheitlichen Ansatz darstellt, da verschiedene Arten von Energieressourcen und Energiemärkten in das aggregierte Energiemanagement einer Gemeinschaft von Haushalten integriert werden, und zum Anderen in der Modellierung der technischen Restriktionen der Energieressourcen, insbesondere von Power-to-Heat-Systemen mit Wärmepumpen, einen hohen Detailgrad aufweist. Im Rahmen einer Fallstudie mit zwei saisonalen Szenarien, bestehend aus jeweils 62 Tagen, wird das EAM für die Day-Ahead-Planung von bis zu 111 Haushalten verifiziert und validiert. Die Ergebnisse zeigen, dass die beteiligten Haushalte durch den EA klare wirtschaftliche Mehrwerte erreichen können und dass diese Mehrwerte auf komplexen Synergien zwischen den Systemkomponenten beruhen, die nur durch die ganzheitliche und differenzierte Modellierung erfasst werden können. In weiteren Analysen wird eine zusätzliche Verbesserung der Effizienz des Energiemanagements von EAs durch eine vorausschauende Nutzung von Energiespeichern betrachtet. Dabei werden standardisierte Strategien identifiziert, die jeweils für verschiedene Konstellationen von Tagen zu einer Erhöhung der Handelsüberschüsse der Haushalte beitragen. Zudem wird eine Fairnessanalyse durchgeführt, die zeigt, dass der im EAM abgebildete interne Handel zwischen Haushalten hinsichtlich des Aspekts der Fairness problematisch ist, da der Gemeinschaft zur Verfügung gestellte Flexibilität nicht ausreichend belohnt wird. Als Ansatz zur Behebung dieses Zustands wird eine ex post-Umverteilung der realisierten gemeinschaftlichen Überschüsse vorgeschlagen.
Im Weiteren wird das EAM im Kontext lokaler Energiemärkte betrachtet. Dazu wird ein Modell eines lokalen Marktes entwickelt, das in einen übergeordneten Day-AheadProzess zusammen mit dem EAM integriert wird und damit iterativ einen lokalen Energiehandel zwischen EAs abbildet. Die Anwendung in einer Fallstudie zeigt, dass die Art der Zusammensetzung der Haushalte von EAs starken Einfluss auf die entstehenden Handelsbeziehungen hat. So ist eine Spezialisierung von EAs auf jeweils bestimmte Typen von Haushalten, sodass die EAs zueinander heterogen sind, hinsichtlich der Wirksamkeit des lokalen Marktes von Vorteil gegenüber einer Menge unspezialisierter und somit gleichartiger EAs, die hingegen mehr internen Energieaustausch zwischen den Haushalten der jeweiligen EAs bewirkt. Für den Fall einer heterogenen Zusammensetzung von EAs wird in einer weiteren Untersuchung die Möglichkeit gezielter Markteingriffe zur Reduktion von Leitungsüberlastungen analysiert. Ein Vergleich vier verschiedener Maßnahmenansätze in jeweils neun Varianten führt zu dem Ergebnis, dass ein solcher marktbasierter Ansatz positiv zur Reduktion von Leitungsüberlastungen beitragen kann, dass das Potential jedoch begrenzt ist und die vorgestellten Ansätze somit unterstützend zu anderen Tools des Engpassmanagements zu betrachten sind.
Im Fazit zeigt sich, dass EAs eine wichtige Funktion in zukünftigen Energiesystemen einnehmen können, indem sie für Haushalte wirtschaftlich effizientes Energiemanagement betreiben. Das in dieser Arbeit entwickelte EAM stellt ein Basismodell dar, um die Entscheidungsprobleme eines solchen Energiemanagements abzubilden. Dabei bestehen viele Konfigurationsmöglichkeiten und Einflussfaktoren, die für eine erfolgreiche Anwendung des Konzepts und zur Realisierung des Potentials von EAs zu berücksichtigen sind.In this work, a mixed-integer linear optimization model is developed to depict the decision-making problem of energy aggregators (EAs), which includes the deployment planning of various types of flexible energy resources and the trading of energy on different markets for a set of households assigned to the EA. The central research contribution compared to previous works in the development of the EA model (EAM) is that, on the one hand, it represents a holistic approach, as different types of energy resources and energy markets are integrated into the aggregated energy management of a community of households, and on the other hand, it features a high level of detail in the modeling of the technical restrictions of energy resources, in particular power-to-heat systems with heat pumps. In a case study with two seasonal scenarios, each consisting of 62 days, the EAM is verified and validated for day-ahead planning for up to 111 households. The results show that the participating households can achieve clear economic added value through the EA and that this added value is based on complex synergies between the system components, which can only be exploited through holistic and differentiated modeling. Further analyses consider an additional improvement in the efficiency of EA energy management through the foresighted use of energy storage systems. Standardized strategies are identified that contribute to an increase in household trading surpluses for different constellations of days. In addition, a fairness analysis is carried out, which shows that the internal trading between households depicted in the EAM is problematic in terms of fairness, as the flexibility provided to the community is not sufficiently rewarded. An ex-post redistribution of the realized community surpluses is proposed as an approach to improve fairness between households.
Furthermore, the EAM is considered in the context of local energy markets. For this purpose, a model of a local market is developed that is integrated into a higher-level day-ahead process together with the EAM, thereby iteratively depicting local energy trading between EAs. Application in a case study shows that the composition of EAs' households has a strong influence on the resulting trading relationships. For example, specialization of EAs in specific types of households, resulting in heterogeneity among EAs, is advantageous in terms of local market efficiency compared to a set of unspecialized and thus homogeneous EAs, which, on the other hand, results in more internal energy exchange between the households of the respective EAs. In the case of a heterogeneous composition of EAs, a further study analyzes the possibility of targeted market interventions to reduce line congestion. A comparison of four different approaches, each with nine variants, leads to the conclusion that such a market-based approach can contribute positively to reducing line congestion, but that the potential is limited and the approaches presented should therefore be considered as supporting other congestion management tools.
In conclusion, it is clear that EAs can play an important role in future energy systems by providing economically efficient energy management for households. The EAM developed in this thesis represents a basic model for depicting the decision-making problems of such energy management. There are many configuration options and influencing factors that must be taken into account for the successful application of the concept and the realization of the potential of EAs
Legal implications of vision-language foundation models (VLFM) in industrial applications in Europe: an inquiry into data protection, copyright, and AI regulation
No full textThe rise of Foundation Models (FM) starts to revolutionize different aspects of machine vision in industrial applications. Increased generalizability, robustness, reliability, and the capacity for few-shot learning make vision systems adaptable and flexible to an unprecedented degree. Yet, the development and deployment of fine-tuned models in the industrial domain face unique legal challenges in Europe that arise from stringent regulations, including Copyright Law, the General Data Protection Regulation (GDPR), and the recently enacted AI Act. In this work, we investigate the legal implications of pre-training (1), fine-tuning (2), and utilizing VFMs (3) in industrial contexts in Europe, with a specific focus on manufacturing. With this contribution, we aim to raise awareness on how various regulations will impact the use of VLFMs in industrial settings
Multivalent ion-crosslinked alginate–montmorillonite nanocomposite hydrogels for hydrophilic drug release
No full textControlled delivery of hydrophilic drugs remains a major challenge due to their high water solubility and rapid diffusion. This study aims to address this issue by developing alginate–montmorillonite (MMT) nanocomposite hydrogels crosslinked with different multivalent cations (Fe3+, Cu2+, Sr2+, and Ca2+) and systematically analyzing their effects on drug encapsulation and release. Hydrogels were evaluated for structural morphology using Scanning Electron Microscopy (SEM), while swelling studies were used to determine mesh size (ranging from 34 to 58 nm) and diffusion coefficients. Drug release was quantified at pH 7 and 37 °C using UV/Vis spectroscopy and fitted to mathematical models to identify the release mechanism. The Fe3+-crosslinked hydrogel showed the highest encapsulation efficiency (98 %) and the slowest release rate. By correlating the formation constants of each cation with their diffusivity, a predictive model was developed to guide formulation modifications for tuning the release profile. These results demonstrate that cation selection significantly influences the physicochemical properties of alginate–MMT hydrogels and offer a quantitative framework for designing tunable drug delivery systems based on nanocomposites hydrogel
Fast and fractionated: correlation of dose attenuation and the response of human cancer cells in a new anthropomorphic brain phantom
No full textThe results of radiotherapy in patients with primary malignant brain tumors are extremely dissatisfactory: the overall survival after a diagnosis of glioblastoma is typically less than three years. The development of spatially fractionated radiotherapy techniques could help to improve this bleak prognosis. In order to develop technical equipment and organ-specific therapy plans, dosimetry studies as well as radiobiology studies are conducted. Although perfect spheres are considered optimal phantoms by physicists, this does not reflect the wide variety of head sizes and shapes in our patient community. Depth from surface and X-ray dose absorption by tissue between dose entry point and target, two key parameters in medical physics planning, are largely determined by the shape and thickness of the skull bone. We have, therefore, designed and produced a biomimetic tool to correlate measured technical dose and biological response in human cancer cells: a brain phantom, produced from tissue-equivalent materials. In a first pilot study, utilizing our phantom to correlate technical dose measurements and metabolic response to radiation in human cancer cell lines, we demonstrate why an anthropomorphic phantom is preferable over a simple spheroid phantom
Digital-twin-based structural health monitoring of dikes
No full textEarthen flood protection structures are planned and constructed with an expected service life of several decades while being exposed to environmental impacts that may lead to structural or hydraulic failure. Current maintenance procedures involve only repairing external damage, leaving internal processes contributing to structural damage often undetected. Through structural health monitoring (SHM), structural deficits can be detected before visible damage occurs. To improve maintenance workflows and support predictive maintenance of dikes, this paper reports on the integration of digital twin concepts with SHM strategies, referred to as “digital-twin-based SHM”. A digital twin concept, including a standard-compliant building information model, is proposed and implemented in terms of a digital twin environment. For integrating monitoring and sensor data into the digital twin environment, a customized webform is designed. A communication protocol links preprocessed sensor data stored on a server with the digital twin environment, enabling model-based visualization and contextualization of the sensor data. As will be shown in this paper, a digital twin environment is set up and managed in the context of SHM in compliance with technical standards and using well-established software tools. In conclusion, digital-twin-based SHM, as proposed in this paper, has proven to advance predictive maintenance of dikes, contributing to the resilience of critical infrastructure against environmental impacts
ClusterSim: modeling thread block clusters in hopper GPUs
No full textModern Graphics Processing Units (GPUs), such as NVIDIA’s Hopper and Blackwell, leverage Thread Block Clusters (TBCs) to enhance performance and resource management. TBCs introduce a hierarchical organization, grouping thread blocks into clusters that enable efficient synchronization and distributed shared memory access. This innovation improves data locality and reduces latency in inter-thread block communication, unlocking new opportunities for executing complex parallel workloads. However, modeling the intricate interactions within TBCs, especially the balance between data locality and resource contention, is challenging. This is further complicated by limited access to cutting-edge hardware like Hopper GPUs, which restricts direct experimentation. As a result, robust simulation models are needed to accurately replicate TBC behavior. This paper presents a detailed simulation model that captures TBC performance characteristics. Our model enables researchers to explore TBC functionalities and evaluate performance implications without requiring physical Hopper GPUs. Validation against an NVIDIA H100 GPU shows a Mean Absolute Relative Error (MARE) of 4.7%, demonstrating the model’s accuracy and utility for advancing research in GPU architectures and parallel computing
Revisiting directed disjoint paths on tournaments (and relatives)
No full textIn the Directed Disjoint Paths problem (k-DDP), we are given a digraph and k pairs of terminals, and the goal is to find k pairwise vertex-disjoint paths connecting each pair of terminals. Bang-Jensen and Thomassen [SIAM J. Discrete Math. 1992] claimed that k-DDP is NP-complete on tournaments, and this result triggered a very active line of research about the complexity of the problem on tournaments and natural superclasses. We identify a flaw in their proof, which has been acknowledged by the authors, and provide a new NP-completeness proof. From an algorithmic point of view, Fomin and Pilipczuk [J. Comb. Theory B 2019] provided an FPT algorithm for the edge-disjoint version of the problem on semicomplete digraphs, and showed that their technique cannot work for the vertex-disjoint version. We overcome this obstacle by showing that the version of k-DDP where we allow congestion c on the vertices is FPT on semicomplete digraphs provided that c is greater than k/2. This is based on a quite elaborate irrelevant vertex argument inspired by the edge-disjoint version, and we show that our choice of c is best possible for this technique, with a counterexample with no irrelevant vertices when c ≤ k/2. We also prove that k-DDP on digraphs that can be partitioned into h semicomplete digraphs is W[1]-hard parameterized by k + h, which shows that the XP algorithm presented by Chudnovsky, Scott, and Seymour [J. Comb. Theory B 2019] is essentially optimal
Leistungsbeurteilung
No full textDie Bewertung von Studierendenleistungen hat eine wichtige didaktische Funktion im Lernprozess. Durch sie erhalten Lehrende und Studierende Rückmeldung zum Leistungsstand sowie zu Stärken und Verbesserungspotenzialen. Dadurch können sie den bisherigen Erfolg des Lehr-Lern-Prozesses einschätzen und nächste Lehr-Lern-Schritte planen. Der Beitrag stellt grundlegende Elemente der Leistungsbewertung vor und fragt, wie sich die Qualität von Bewertungen beurteilen lässt, wie sich diese lernförderlich gestalten lassen und welche Bewertungsinstrumente genutzt werden können. Im zweiten, stark praxisorientierten Teil liegt der Fokus darauf, wie Bewertungsbögen konstruiert und wie Bewertungen sinnvoll und effektiv durchgeführt werden könne
Ice trails with “Le Commandant Charcot” for load assessment
No full textThe Arctic Ocean is in a process of significant changes, which also raises the interest in exploring these changes. This also concerns the performance of ships and how different operational profiles together with climate change are affecting current and future designs. This paper presents ice trials with a PC2 ice classed ship during a Trans-Arctic voyage, where continuously data such as ice thickness and accelerations are measured. From these data the number of ice impacts is determined which is used in a probabilistic extreme ice load assessment. The probabilistic ice pressures are compared with the design pressures from the Polar Ice Classes. The results indicate a significant loading of the structure with a potential to exceed Ice Class values. The analysis and results contain uncertainties, as the applied state of the art needs to be updated with new measurements and data accounting for climate change. A detailed analysis during one ice trail with constant power indicated that ridges contribute significantly to the number of impacts, while recent research on Arctic survey indicates that the ice surface becomes smoother and the number of ridges reduce
Facile spin-coated MoS₂ thin films from a single-source precursor for HER activity
No full textHydrogen evolution reaction (HER) is one of the most promising ways to replace the consumption of fossil fuels
with a clean and green energy source. HER requires a suitable material as a catalyst to lower overpotential and minimize energy
consumption. MoS2 is an excellent candidate for the HER because of its suitable band structure. It is an economical and earthabundant
material compared to the standard electrode for HER, i.e., Pt. MoS2 thin films can be engineered to produce active sites for
HER. We prepared large area thin films of MoS2 from a Mo single source precursor (MoCl5) by means of spin coating, followed by
post-annealing (sulfurization) with an additional sulfur source in an Ar/H2 environment. The obtained films have been characterized
by Raman, X-ray diffraction (XRD), UV−vis, and X-ray photoelectron spectroscopy (XPS) before and after post-annealing. The
obtained MoS2 films are found to be active for HER activity. The HER activity for a 10 nm thick MoS2 film is determined at an
overvoltage of 290 mV, while for 50 nm films, HER activity is observed at 369 mV at a current density of 10 mA/cm2. The HER
performance of the thinner films of MoS2 is better than that of the thicker films of MoS2. XPS results show that the obtained MoS2
films have sulfur deficiency (S-vacancies), which is beneficial for HER activity. The Tafel slope extracted from the polarization curve
is 80 mV per decade, which is superior to those of single-crystal MoS2 and other 2D TMD materials