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An Extended Krylov Subspace Method for Decoding Edge‐Based Compressed Images by Homogeneous Diffusion
Get PDFThe heat equation is often used to inpaint dropped data in inpainting-based lossy compression schemes. We propose an alternative way to numerically solve the heat equation by an extended Krylov subspace method. The method is very efficient with respect to the computation of the solution of the heat equation at large times. And this is exactly what is needed for decoding edge-compressed pictures by homogeneous diffusion
Beschleunigtes Materialdesign durch künstliche Intelligenz im Forschungsdatenmanagement
Get PDFAm Beispiel von Polyurethanschaumstrukturen entwickelt diese Arbeit einen modularen, FAIRen Workflow für datengetriebene Materialentwicklung. Über KI-basierte Segmentierung, generative 3D-Modelle und Simulationen werden mikrostrukturelle Eigenschaften automatisiert analysiert und mechanische Kennwerte zuverlässig vorhergesagt. Die generischen Workflows und eine transparente Datenverwaltung beschleunigen den Entwicklungsprozess und lassen sich flexibel auf andere Materialien übertragen
Engineering Manganese Oxide‐Decorated Carbon Stacks with Layered‐Inspired Architecture for Lithium‐Ion Capacitors
No full textSolubility, Speciation and Thermodynamics of PuCO₃OH(cr) in Carbonate Containing NaCl Solutions
No full textHigh‐Rate FA‐Based Co‐Evaporated Perovskites: Understanding Rate Limitations and Practical Considerations to Overcome Their Impact
No full textVapor phase deposition methods are readily able to achieve uniform coverage of large-area substrates and are widely considered promising for industrial-scale perovskite solar cell fabrication. However, as perovskite-silicon tandem solar cells approach commercialization, practical considerations of manufacturing throughput come into play. Here, it is shown that the inherent sublimation characteristics of the organic precursor formamidinium iodide (FAI) make increasing the deposition rate of FA-based co-evaporated perovskites negatively impact replicability and lead to a substantial decrease in power conversion efficiency (PCE). These losses are linked to reduced film homogeneity and the emergence of carbon-rich regions within the perovskite layer. To mitigate these rate-induced effects, two approaches are explored: source layout optimization and material preconditioning. Utilizing dual FAI sources rather than a single FAI source reduces the relative PCE drop from ≈23%rel to ≈9%rel at a deposition rate of ≈18 nm min−1 (14.8% PCE @ maximum power point (MPP)) compared to the baseline rate of 5 nm min−1 (16.2% PCE @MPP). Alternatively, preconditioning a single FAI source reduces the performance losses from ≈31%rel to ≈26%rel at a deposition rate of ≈21 nm min−1. These findings underscore the importance of tailored source strategies to enable high-rate FA-based co-evaporated perovskites without compromising device performance
Attack Once, Compromise All? On the Scalability of Attacks
No full textElectronic voting schemes are often criticized for being insecure, on the grounds that a successful attack would allow an adversary to manipulate all votes at once. It is argued that attacks therefore have a higher impact at lower adversary costs compared to paper-based schemes, where attacks are cumbersome. In this paper, we propose a framework to quantify how prone different protocols are to attacks that scale well. For this purpose, we introduce the notion of scalability of attacks. We give the adversary access to an oracle which can break common cryptographic building blocks and assumptions and analyze how many inputs of a (multiparty computation) protocol they can learn or manipulate for each oracle access. The more inputs are affected, the more susceptible the protocol is to attacks that scale well. We compare several pairs of protocols solving the same problem in different ways in three examples and analyze the scalability of attacks on each protocol. We find that some protocols have a fatal breakdown, i.e. all inputs are affected with only one access to the oracle, while other protocols scale linearly or have a threshold, where the number of affected inputs increases drastically from one access to the other. Our framework provides strong arguments in favoring one voting scheme over another. It enables voting authorities to compare schemes that appear equally secure at first glance, and to consider the scalability of attacks when deciding on a scheme
Screening of Six Different Potential HLRW Canister Materials Surrounded by Bentonite
No full textMost countries seeking strategies for the disposal of high-level nuclear (HLW) waste envisage the use of metallic
containers. In some deep geological repositories, the canister will be in contact with bentonite. Different types of metals
were tested so far with ambiguous results. Consistent data are available for copper and carbon steel. Different performances, however, were reported for stainless steel. In the present study six different alloys were tested: three iron-matrix alloys with different carbon contents and grain sizes, a copper-nickel alloy, zirconium, and stainless steel. They were immersed with water saturated bentonite for 10 months at 23°C under anaerobic conditions. Corrosion was assessed gravimetrically and using electron- and X-ray microscopy. Stainless steel did not show any reaction with the bentonite despite its widespread classification as disadvantageous because of its susceptibility for local corrosion at low pH and high Cl- concentrations. Many studies using stainless steel, however, were conducted with simulating bentonite pore waters but without contact with bentonite which meanwhile is known to buffer both pH and redox potential (Eh).
The promising results of the stainless-steel corrosion tests in the present study encourage further systematic investigations to improve the predictability of stainless-steel performance as HLW canister material surrounded by bentonite
Vom Rauchgas zur Ressource: moderne Verfahren zur CO2-Abscheidung im Überblick
No full textVerfahren zur Abscheidung von CO2 sind seit langem in unterschiedlichen Anwendungsfällen, z. B. in der Synthesegas-, Erdgas- und Biogas-Technik, etabliert. Intensiv erforscht, aber bislang in der industriellen Praxis nicht weit verbreitet, ist die CO2-Abscheidung aus dem Rauchgas von Verbrennungsprozessen. Diese könnte in Zukunft zur Minderung von Treibhausgasemissionen stark an Bedeutung gewinnen. Eine potenzielle Zukunftstechnologie kann zudem die Gewinnung von CO2 aus Luft sein, auch als Direct Air Capture (DAC) bezeichnet
The infrared imaging video bolometer at Wendelstein 7-X
No full textThe radiated power distribution is a crucial aspect of heat transport, heat load mitigation, and plasma exhaust performance. An imaging video bolometer camera has been installed to measure the plasma radiated power in the divertor region of the Wendelstein 7-X (W7-X) stellarator. This diagnostic offers a wide-angle (40° × 68°) sampling of the plasma volume in both the poloidal and toroidal directions. The field-of-view is covered with a large number (>500) of bolometer channels, providing imaging capability. The diagnostic design is introduced here together with its data analysis procedure. A set of laboratory experiments is performed to assess the thermal properties of the gold absorber foil and their spatial uniformity. Following installation, a heat source originating from the inertially cooled front of the diagnostic is identified and filtered out. The discharge data indicate a satisfactory signal-to-noise ratio as well as spatiotemporal resolution. These represent the first toroidally resolved images of the line-integrated radiated power in the W7-X island divertor. The diagnostic was then upgraded with a thinner platinum absorber and adjusted mirrors. Early data from the most recent experimental campaign employing the upgraded design show a considerable improvement in the diagnostic performance with more bolometer channels (>1400) , extended coverage, and increased spatial resolution
