Passivity-Based Stabilisation and Coordination in Networked Multi-Energy Systems

Das Ziel, sogenannte Netto-Null-Emissionen zu erreichen, führt zu einer Transformation der Energienetze mit einer zunehmenden Abhängigkeit von volatilen, erneuerbaren Energiequellen. Gleichzeitig bieten neue Technologien die Chance, durch die Kopplung von Energienetzen und intelligenten Lasten, eine höhere Flexibilität zu erzielen. Um die Flexibilitätsvorteile solcher zukünftiger vernetzter Multienergiesysteme mit ihrem hohen Maß an Volatilität und Verkopplung voll ausschöpfen zu können, ist jedoch ein dynamisch stabiler Betrieb erforderlich. Die vorliegende Dissertation befasst sich mit den Herausforderungen der dynamischen Stabilität für Gleichstromnetze, Gasnetze und vernetzte Multienergiesysteme. Es werden Regler für die dezentrale Stabilisierung und verteilte Koordination in Gleichstromnetzen mit nichtlinearen Lasten und ohne flächendeckende Leistungsverfügbarkeit an den Lasten entworfen. Des Weiteren werden Regleransätze für eine dezentrale Stabilisierung von Gasnetzen mit Kompressoren präsentiert, die potentiell lokale Überangebote an Gas aufweisen. Die derart geregelten Gleichstrom- und Gasnetze werden über Kopplungskomponenten zu vernetzten Multienergiesystemen zusammengeführt. Die Stabilität eines solchen dynamischen vernetzten Multienergiesystems lässt sich aus den Stabilitätsergebnissen seiner konstitutiven Netze ableiten. Die Skalierbarkeit der Ergebnisse für Energienetze und vernetzte Multienergiesysteme ist durch die Verwendung von ruhelangenunabhängiger Passivität sichergestellt. Darüber hinaus gewährleistet die ruhelangenunabhängige Passivität eine Modularität, welche die Substitution jeder Komponente oder jeden Reglers durch andere Versionen mit gleichwertigen Passivitätseigenschaften ermöglicht. Die Stabilitätsergebnisse sind nachweislich robust gegenüber Netztopologie- und Parameteränderungen. Diese Erkenntnisse werden durch umfangreiche Simulationsstudien belegt. Zudem zeigen die Simulationen, wie sich transiente Effekte zwischen den enthaltenen Einzelnetzen in einem vernetzten Multienergiesystem ausbreiten können. Die präsentierten Regler sowie die Methoden der Stabilitätsanalyse eröffnen somit die Möglichkeit einer optimierten Koordination in zukünftigen vernetzten Multienergiesystemen mit garantierter Stabilität

Scalable and Fine-Tuned Privacy Pass from Group Verifiable Random Functions

Anonymous token schemes are cryptographic protocols for limiting the access to online resources to credible users. The resource provider issues a set of access tokens to the credible user that they can later redeem anonymously, i.e., without the provider being able to link their redemptions. When combined with credibility tests such as CAPTCHAs, anonymous token schemes can significantly increase user experience and provider security, without exposing user access patterns to providers. Current anonymous token schemes such as the Privacy Pass protocol by Davidson et al. rely on oblivious pseudorandom functions (OPRFs), which let server and user jointly compute randomly looking access tokens. For those protocols, token issuing costs are linear in the number of requested tokens. In this work, we propose a new approach for building anonymous token schemes. Instead of relying on two-party computation to realize a privacy-preserving pseudorandom function evaluation, we propose to offload token generation to the user by using group verifiable random functions (GVRFs). GVRFs are a new cryptographic primitive that allow users to produce verifiable pseudorandomness. Opposed to standard VRFs, verification is anonymous within the group of credible users. We give a construction of group VRFs from the Dodis-Yampolskiy VRF and Equivalence- Class Signatures, based on pairings and a new Diffie- Hellman inversion assumption that we analyze in the Generic Group Model. Our construction enjoys compact public keys and proofs, while evaluation and verification costs are only slightly increased compared to the Dodis-Yampolskiy VRF. By deploying a group VRF instead of a OPRF, we obtain an anonymous token scheme where communication as well as server-side computation during the issuing phase is constant and independent of the number of tokens a user requests. Moreover, by means of our new concept of updatable token policies, the number of unspent tokens in circulation can retrospectively (i.e., even after the credibility check) be decreased or increased in order to react to the current or expected network situation. Our tokens are further countable and publicly verifiable. This comes at the cost of higher computational efforts for token redemption and verification as well as somewhat weaker unlinkability guarantees compared to Privacy Pass

CORSIKA 8: A modern and universal framework for particle cascade simulations

CORSIKA 8 represents a significant update in the simulation of particle showers, building on the well-established foundation of CORSIKA 7. It has been entirely rewritten as a modular and modern C++ framework, addressing the limitations of its predecessor to provide a flexible platform designed to satisfy current and novel use cases. This allows for application beyond pure air-shower scenarios such as cross-media particle cascades and an advanced calculation of the radio emission. A first official ``physics-complete\u27\u27 version has already been released that supports the treatment of hadronic interactions with Sibyll 2.3d, QGSJet-II.04, and EPOS-LHC and the treatment of the electromagnetic cascade with PROPOSAL 7.6.2. In this presentation, we will discuss the design principles, current functionality, and validation efforts of CORSIKA 8, emphasizing its potential applications for future experiments

Control of a Modular Multiport Solid State Transformer for a Flexible High Power Charging Infrastructure

This paper presents a control strategy for a Multiport Solid-State Transformer designed to connect multiple EV charging stations to the medium-voltage AC grid. The transformer employs a Cascaded H-Bridge converter composed of identical switching cells, each incor- porating a Dual Active Bridge to provide galvanic isolation between the AC grid and the charging ports. Steady-state modelling of the multilevel converter is used to identify the permissible power imbalance between charging ports, ensuring stable operation. The proposed real-time control method facilitates independent output power control for each port while maintaining effective cell voltage balancing across the converter. Furthermore, dynamic switch matrix reconfiguration enhance the converter’s operational range. The control strategy is validated through simulations and experimental measurements, demonstrating improved flexibility and performance for scalable EV charging infrastructure

NovaCrate v1.0.0

Web-based interactive editor for creating, editing and visualizing research object crates

Room‐temperature dislocation plasticity in ceramics: Methods, materials, and mechanisms

Dislocation-mediated plastic deformation in ceramic materials has sparked renewed research interest due to the technological potential of dislocations. Despite the long research history of dislocations as one-dimensional lattice defects in crystalline solids, the understanding of plastically deformable ceramics at room temperature seems lacking. The conventional view holds that ceramics are brittle, difficult to deform at room temperature and exhibit no dislocation plasticity except in small-scale testing such as nanoindentation and nano-/micropillar compression. In this review, we attempt to gather the evidence and reports of room-temperature dislocation plasticity in ceramics beyond the nano-/microscale, with a focus on meso-/macroscale plasticity. First, we present a mechanical deformation toolbox covering various experimental approaches for assessing the dislocation plasticity and highlighting bulk plasticity. Second, we provide a materials toolbox listing 44 ceramic compounds that have been reported to exhibit dislocation plasticity at meso-/macroscale under ambient conditions. Finally, we discuss the mechanics of dislocations in ceramics, aiming to establish a foundation for predicting and discovering additional ceramics capable of room-temperature plastic deformation, thereby advancing the development of prospective dislocation-based technologies

Scripts for local SSIM analysis and Fourier ring correlation assessment of live zebrafish embryos in sphere stage

Scripts for local SSIM analysis and Fourier ring correlation assessment to show how far the SNR of the image can be compromised to let n2v recover the SNR post-acquisition. Download “Raw images.zip” which contains the raw data. Images are recruited RNA polymerase II (Pol II Ser5P and Ser2P) in live sphere stage zebrafish embryos, visualized with antibody fragments (Fab) labelled with Janelia fluor 647. Download and unzip “Processed_images.zip” which contains the TIF images of Pol II Ser5P images and the corresponding n2v_processed images. Python script named “zebrafish_nuclei_photo.py” generates images that are single image planes and were acquired with different exposure times. Intensity scale from black to white adjusted to the 0.01-th and the 99.99-th percentile. Matlab script named “lowestSSIMPercentile4zebrafish.m” generates average SSIM values based on the 5% lowest local SSIM values of the 5% brightest pixels. Python script “FRC_zebrafish.py” calculates the effective resolution as determined by FRC analysis for low-quality images, reconstructed images, and high-quality images for the different exposure times. “spin_average.py” file contains a function that is used in “FRC_zebrafish.py”