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Sodium-ion battery cost projections and their impact on the global energy system transition until 2050
No full textSodium-ion batteries (SIB) have recently emerged as an alternative to current lithium-ion batteries (LIB), using low-cost and abundant raw materials. However, previous assessments have come to controversial results regarding their economic competitiveness, and the potential impacts of SIB on the wider energy system are still unexplored. This study combines a bottom-up cost modelling including future performance developments on material level for SIB with a global energy system model to obtain a comprehensive assessment of the potential impact of SIB on the global energy-industry transition until 2050. The results show that with recent cost developments and learning curves, batteries are no longer a cost-critical component in the energy system with projected utility-scale battery system capex of 28.5–51.9 €/kWh by 2050. SIB potentially outperform LIB on the medium term and are less prone to price spikes and supply shortages. Being a so-called drop-in technology, they could be produced on existing LIB production lines with only minor modifications. Therefore, concerns about supply shortages or price increases can be seen as resolved, since any disturbance in LIB supply would simply trigger a shift to SIB. The overall energy system structure remains virtually unaffected, with similar solar photovoltaic shares, but a shift in power-to-X processes operation. In this sense, electrochemical energy storage is not found to be a limiting factor for the global energy transition. Correspondingly, this work projects the possibly highest stationary battery demand published with a range of 67.9–106.5 TWh by 2050, above those in existing cost-optimised energy-industry system analyses
Towards improved accounting and mitigation of greenhouse gas emissions from ditches and canals
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Effizientes Fuzzing von IoT-Geräten
No full textFuzzing ist eine bewährte Methode zur Identifizierung von Sicherheitslücken in Software. In dieser Dissertation wird untersucht, wie sich die Effizienz des Fuzzings für IoT-Geräte, am Beispiel des ESP32-Mikrocontrollers, steigern lässt. Während Fuzzing in klassischen Softwareumgebungen etabliert ist, fehlen speziell angepasste Verfahren für ressourcenarme IoT-Hardware. Das Ziel besteht in der Entwicklung eines konzeptionellen Frameworks, das eine umfassende und effiziente Testung trotz begrenzter IoT-Ressourcen ermöglicht. Zu diesem Zweck werden vier Ansätze zur Effizienzsteigerung sowie ein Konzept zur flexiblen Kombination dieser Ansätze vorgestellt.
Beim Binary Rewriting wird Binärcode so modifiziert, dass die Funktionalität erhalten bleibt. Für viele gängige Architekturen existieren bereits entsprechende Verfahren. Für die Xtensa-Architektur des ESP32 gab es jedoch bislang keine Lösung. In dieser Dissertation wird gezeigt, wie sich Binary Rewriting auf dem ESP32 umsetzen lässt, um Fuzzing-Instrumentierungen direkt in die Firmware zu integrieren und Laufzeitinformationen an den Fuzzer zurückzumelden.
Zudem wurde die Emulationsumgebung des ESP32 erheblich erweitert. Dadurch ist nun Fuzzing von beliebiger Firmware möglich, auch von Firmware mit zuvor nicht unterstützten Hardwarekomponenten. Im Vergleich zur realen Hardware arbeitet die Emulation deutlich effizienter. Während hardwarebasiertes Fuzzing vier bis 40 Anfragen pro Sekunde verarbeitet, sind es in der Emulation bis zu 320 Anfragen pro Sekunde.
Zur Generierung valider Eingaben wurde ein Verfahren zum automatisierten Protocol Reverse Engineering (PRE) entwickelt, das Künstliche Neuronale Netze (KNNs) verwendet. Während PRE bislang manuell erfolgen musste, können nun Protokollstrukturen automatisch abgeleitet und damit syntaktisch korrekte Netzwerkpakete erzeugt werden. In den Tests waren 67,6 % der erzeugten HTTP-Pakete und 100 % der FTP-Pakete gültig.
Für das grammatikbasierte Fuzzing wird ein Ansatz mittels Large Language Models (LLMs) vorgestellt. Die zentrale Herausforderung bestand in der effizienten Integration des LLM in den Fuzzing-Prozess. Mithilfe der entwickelten Methode lassen sich syntaktisch und semantisch korrekte XML-Dateien generieren. Dies steigert die Programmflussabdeckung um den Faktor sechs gegenüber einer Ausführung ohne LLM und erreicht eine um 50 % höhere Abdeckung als klassische grammatikbasierte Fuzzer.
Abschließend wird ein Integrationskonzept präsentiert, das eine flexible Kombination der Ansätze ermöglicht und deren Verbesserungen additiv nutzbar macht. Dadurch trägt das Framework zur Effizienzsteigerung des Fuzzings von IoT-Geräten bei. Die Dissertation leistet somit einen wichtigen Beitrag zur praxisnahen Absicherung von IoT-Geräten
Automatic Performance Modeling and Analysis of Configurable Scientific Software and Workflows
No full textThis work reduces the cost of automatic performance modeling and enables comparative analysis of workflow orchestration performance. We use parametric profiles to cut measurement costs, a method to identify performance-irrelevant options, and a serverless workflow benchmarking suite based on a Petri Net model. These contributions help developers and scientists better understand, model, and optimize application performance across diverse platforms and configurations
Assignment of Si-O vibrational modes in the IR spectra of C-S-H phases based on single-crystal polarized IR and Raman spectra of 14 A tobermorite, jennite, and jaffeite
No full textThis article explains the vibrational modes in the Si–O stretching range in the IR spectra of synthetic C-S-H phases with varying C/S ratios. These are compared with selected in situ spectra of hydrates of OPC, and those of synthetic crystalline hydrates. The assignments were supported by 29Si NMR and trimethylsilylation (TMS) data. IR and Raman polarized spectra of oriented crystals of 14 Å tobermorite, jennite and jaffeite enabled direct observation of the Si–O vibrational modes. They were successfully resolved based on the involvement of specific silicon (paired, bridging) and oxygen (bridging, non-bridging) atoms, and were compared with existing theoretical data. The resemblance between the IR spectra of synthetic C-S-H and those formed upon hydration of OPC, proves the suitability of model C-S-H phases for understanding hydration processes. Some uncertainties in the assignment of the C-S-H bands observed in existing in situ IR experiments are discussed, and potential sources of error identified
Effects of γ-radiation on the interfacial chemistry of spheroidal graphite cast iron in contact with Wyoming bentonite slurry
No full textInsights into the black box of multimodal meaning-making: investigating the reception of multimodality empirically
No full textThe intention of this article is to clarify the concept of multimodal meaning making from a recipient’s perspective on the basis of empirical data. The data comes from various reception studies in which different methods like eye tracking, knowledge tests, re-narrations, guided interviews or questionnaires were combined to investigate the appropriation of multimodal artifacts such as newspapers, science videos, comics, social media postings, or commercials. The article is structured in such a way that examples and results from various reception studies on newspaper pages, commercials, comics and science videos and comics are presented in order to introduce concepts like attention, non-linearity, intermodality, modal density and modal coherence for clarifying the process of meaning-making.
Investigating meaning-making empirically should not only fill a research gap in the mostly product- and production-oriented approaches to Multimodality, but also help to develop a satisfactory theory of Multimodality. Eye tracking in combination with verbal data reveals that multimodal artefacts have a non-linear structure – even in linear films - that is grasped step by step by the addressees, analogous to a hypertext. The concept of non-linearity opens a path to define the relevance structure of a multimodal arrangement: the relevance of modal elements is the outcome of its mutual contextualization. With this perspective on Multimodality, the central unit of analysis is neither the sign-maker nor the sign itself or its materiality but the interaction between communicator and addressees, for which the modal resources are used. Intermodal relations are analyzed not as constellations of signs, but as complex discursive action addressed with a special intention to an audience or a person. The theoretical result can be summarized as follows: Combining action theory with cooperation theory provides the conceptual tools to analyze meaning-making as a conversational implicature of a discursive action
Air Stable Photo-Redox Active Elusive Cr(III)-Tri-dithiolene-radical Complexes as a New Class of Pseudo-Supercapacitor with High Capacitance: Enhancement of Energy Storage with Heavier Chalcogenide
No full textChromium, an earth-abundant metal with exceptionally high theoretical specific capacity (1546 mAh g⁻¹) at an accessible redox potential -0.74 V vs. RHE, emerges as a promising element for designing high energy density supercapacitors. Besides their exciting chemistry, energy storage devices employing stable redox-active radicals of main-group elements gain increasing attention for sustainable applications. Herein, we present the pseudosupercapacitor properties of two unprecedented, photo-redox active, air-stable Cr(III)-triradical complexes with the general formula [Cr(III)(SS-NHC=EElectrochemical anodes fabricated by coating these complexes onto stainless-steel substrates demonstrate excellent supercapacitance performance. Complex 1 delivers a specific capacitance of 145.2 F g⁻¹, while complex 2 achieves a markedly higher 340.9 F g⁻¹ at 5 mV s⁻¹, centered at E₁/₂ = -0.72 V. Cycling stability is found to reach 81.2% for 1 and 87.3% for 2 after 3000 cycles. The superior activity of 2 arises from substituting sulfur with selenium in the SS-NHC=E •‾ ligand, enhancing redox activity, conductivity, and ion transport. Ragone plot analysis confirms higher energy density (14.63 Wh kg⁻¹ at 252 W kg⁻¹) for 2 compared to 1 (8.76 Wh kg⁻¹ at 211 W kg⁻¹). Mechanistic studies reveal that 1 operates via mixed surfaceand diffusion-controlled processes, while 2 predominantly follows diffusion control, enabling efficient charge transport and improved pseudocapacitive behavior
Design Limits and Investment Risks of Mid-Term Storage under Uncertain Market Conditions
No full textThe transition to a net-zero energy system requires large-scale integration of variable renewables, increasing demand for flexibility beyond short-term batteries and seasonal hydrogen. Emerging storage technologies feature cost structures that position them between these options, offering discharge durations of several hours to a few days, here referred to as mid-term storage. However, their economic feasibility depends strongly on their techno- economic parameters and evolving market dynamics. Identifying profitable and robust storage configurations under uncertain future market conditions is therefore crucial to bridge the perspectives of technology developers and investors. We employ the agent-based electricity market model PowerACE, which explicitly represents market participants as interacting decision-making agents. Using mean-reverting stochastic representations of fuel prices and renewable generation, we capture the impact of uncertainties on storage profitability from an individual investor’s perspective. The analysis determines the maximum capital expenditure that still yields economically viable storage configurations across relevant combinations of techno-economic parameters.
The results reveal that profitability is limited under current cost conditions, as the marginal contribution of storage capacity declines sharply with higher storage durations. At the same time, higher round-trip efficiency not only improves returns but also reduces market risk. Balancing efficiency, costs, and duration is essential for mid-term storage competitiveness, while risk-based assessments can guide robust technology and investment decisions