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KCLNet: Physics-Informed Power Flow Prediction via Constraints Projections
Get PDFpeer reviewedIn the modern context of power systems, rapid, scalable, and physically plausible power flow predictions are essential for ensuring the grid’s safe and efficient operation. While traditional numerical methods have proven robust, they require extensive computation to maintain physical fidelity under dynamic or contingency conditions. In contrast, recent advancements in artificial intelligence (AI) have significantly improved computational speed; however, they often fail to enforce fundamental physical laws during real-world contingencies, resulting in physically implausible predictions. In this work, we introduce KCLNet, a physics-informed graph neural network that incorporates Kirchhoff’s Current Law as a hard constraint via hyperplane projections. KCLNet attains competitive prediction accuracy while ensuring zero KCL violations, thereby delivering reliable and physically consistent power flow predictions critical to secure the operation of modern smart grids
ENCODING INFORMATION AS UNOBTRUSIVE GRAPHICAL PATTERNS USING CHOLESTERIC SPHERICAL REFLECTORS: FROM OPTICAL AND MATERIALS CHALLENGES TO APPLICATION IN ROBOTICS
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Transformation of International Investment Law and Its Principles: Indirect Expropriation and Fair and Equitable Treatment
No full textpeer reviewedThis book explores how international investment law has evolved through the interpretation of key protection standards like Fair and Equitable Treatment and indirect expropriation. It examines how arbitral decisions have shaped, and been shaped by, state treaty-making practices - particularly in recent "new generation" agreements. The analysis reveals a broader trend toward greater clarity, specificity, and balance in the design of investment treaties.116. Peace, justice and strong institution
Qualitätssicherung in der Entwicklung von Sprach- und Schreibkompetenz Erfahrungen freier Lektor: innen mit KI im mehrsprachigen universitären Kontext
No full textpeer reviewedDas Sprachenzentrum der mehrsprachigen Universität Luxemburg bietet Studienprogrammen Unterstützung für Studierende in den drei offiziellen Unterrichtssprachen Deutsch, Englisch und Französisch an. Ab den mittleren Sprachniveaus wird ein Fokus auf wissenschaftliche Diskurskompetenz gelegt, wobei die Textproduktion einen wichtigen Platz einnimmt. Das Sprachenzentrum beschäftigt neben wenigen fest angestellten Mitarbeiter:innen zwischen 15 und 20 freie Lektor:innen im Bereich der Sprachenlehre und des wissenschaftlichen Schreibens.
In diesem Vortrag werden vor dem Hintergrund aktueller Forschung (Buck et al. 2024; Huemer 2024; Liebetanz et al. 2024) die Ergebnisse einer Umfrage unter den freien Lektor:innen des Sprachenzentrums, durchgeführt im September 2023, sowie Erkenntnisse aus zwei Netzwerktreffen von Lektor:innen und Mitarbeiter:innen des Sprachenzentrums im Herbst 2023 und im Herbst 2024 präsentiert. Ziel dieser Maßnahmen war es, die Erfahrungen und Herausforderungen von Lektor:innen im Umgang mit Künstlicher Intelligenz (KI) in der Sprach- und Schreiblehre zu erheben, erfolgreiche Unterrichtspraktiken zu teilen, Probleme zu identifizieren und Lösungsstrategien zu entwickeln.
Die Umfrage und die Netzwerktreffen haben gezeigt, dass Lektor:innen beim Unterrichten auf verschiedene Probleme stoßen, insbesondere im Hinblick auf die didaktisch sinnvolle Integration von KI-Tools in den Unterricht und die Bewertung von Aufgaben, die sich je nach Sprachniveaustufen und Disziplinen unterschiedlich gestalten. Im Vortrag werden diese Erfahrungen geteilt sowie Lösungsansätze zur Qualitätssicherung diskutiert
Weighted Codebook Scheme for RIS-Assisted Point-to-Point MIMO Communications
No full textpeer reviewedReconfigurable intelligent surfaces (RIS) can reshape the characteristics of wireless channels by intelligently regulating the phase shifts of reflecting elements. Recently, various codebook schemes have been utilized to optimize the reflection coefficients (RCs); however, the selection of the optimal codeword is usually obtained by evaluating a metric of interest. In this letter, we propose a novel weighted design on the discrete Fourier transform (DFT) codebook to obtain the optimal RCs for RIS-assisted point-to-point multiple-input multiple-output (MIMO) systems. Specifically, we first introduce a channel training protocol where we configure the RIS RCs using the DFT codebook to obtain a set of observations through the uplink training process. Secondly, based on these observed samples, the Lagrange multiplier method is utilized to optimize the weights in an iterative manner, which could result in a higher channel capacity for assisting in the downlink data transmission. Thirdly, we investigate the effect of different codeword configuration orders on system performance and design an efficient codeword configuration method based on statistical channel state information (CSI). Finally, numerical simulations are provided to demonstrate the performance of the proposed scheme
Constrained Riemannian Manifold Optimization for the Simultaneous Shaping of Ambiguity Function and Transmit Beampattern
No full textpeer reviewedDesigning the transmit waveforms with prescribed ambiguity functions (AFs) and beampatterns while adhering to the constant modulus (CM) constraint is pivotal for the forthcoming cognitive multiple-input multiple-output (MIMO) radar systems. This study delves into the AF shaping quandary within the MIMO radar framework, considering the joint constraints of waveform unimodality and desired beampattern. The established model explores higher dimensions to realize the waveform design in range–Doppler and spatial dimensions, to improve the possibility of separating target and interference. Specifically, we first formulate the waveform design problem as a jointly constrained quartic problem, with the aim of minimizing the response values corresponding to the different range–Doppler bins within the defined compound AF. Leveraging the geometric properties of CM constraint, we further transform the jointly constrained problem in the Euclidean space into a single-constraint optimization problem in the Riemannian space. Then, the Riemannian augmented Lagrangian method (RALM) is proposed to iteratively search for the optimal waveform. Subsequently, we conduct numerical experiments to validate the efficacy of the RALM algorithm. In addition, we implemented the designed waveforms in hardware systems to analyze the effects induced by nonlinear instruments
Climate action in space: A sustainable development framework for sunshades at Sun-Earth Lagrange Point 1
No full textpeer reviewedSunshades in space have been proposed as a geoengineering method to mitigate climate change by reducing incoming solar radiation. Sunshade concepts are gaining attention as a lower-risk but higher-cost alternative to terrestrial solar radiation management approaches, such as stratospheric aerosol injection. However, the literature is limited, and the absence of a structured development framework complicates the evaluation, comparison, and maturation of these concepts. A shared standard that reflects the wide-ranging aspects of sunshade deployment could streamline efforts, accelerate progress, and improve the recognition of sunshades in the international climate change debate. While aiming to provide sustainability from space, a deployed sunshade must also follow sustainability principles in space given its scale. At the same time, the required industry on Earth should align with broader sustainability goals, ensuring that it does not undermine ongoing efforts towards a sustainable future. Therefore, as a first step, this paper analyzes the applicability of internationally recognized sustainability frameworks – namely the United Nations Sustainable Development Goals and the European Space Agency’s Environmental Impact Indicators for space systems – by employing a content analysis methodology on a representative selection of literature. The insights gained, along with criteria derived from the geoengineering literature, shaped the 18 Sunshade Development Criteria (SDC), a framework for sustainable development. Subsequently, this paper analyzes the case study literature based on the SDC to draw conclusions on the state of the art of the sunshade domain. This framework is the first of its kind and this study is the first that employs a systematic content analysis to evaluate the sunshade literature. The findings indicate that a detailed assessment and comparison of sunshade concepts remain challenging because of the field’s fragmentation. Although criteria such as side effects, controllability, and the overall context of climate change have been covered, significant gaps remain. These include technical maturity, global warming potential, sustainability considerations, distribution of spatio-temporal radiative forcing, public perception, social acceptability, global inequalities, and impacts on the space segment. Addressing these gaps is essential, and the SDC serve as a crucial tool to facilitate this maturation. Beyond purely technical considerations, this paper introduces an interdisciplinary perspective on the sunshade domain while demonstrating this approach through its methodology and proposed framework. It seeks to advance sunshade concepts and guide their sustainable development and deployment to address climate change. Ultimately, it aims to increase the acceptance of sunshades in the international debate on whether and how we should intervene in the climate.Towards A Circular Economy In Space: Ecodesign For Space System Architecting13. Climate actio
An Integrated OTFS-NOMA Framework for Multi-Beam LEO Systems: Reliability and Capacity Analysis
No full textpeer reviewedMulti-beam low earth orbit (LEO) satellite communications, as an essential component for 6G systems, may encounter challenges from severe Doppler shifts and co-channel interference. This paper addresses a realistic problem in 6G-LEO systems, that is, how to meet the high-reliability demands of massive high-mobility terminals. We propose an integrated framework to exploit the synergy of non-orthogonal multiple access (NOMA) and orthogonal time frequency space (OTFS). OTFS modulation is employed to achieve full time-frequency diversity to combat Doppler shifts, while NOMA is used to accommodate more access requests. Specifically, within each beam, power domain superposition is applied to the delay-Doppler domain, enabling multiple terminals to share delay-Doppler grid resources. We analyze the performance of reliability, outage probability and ergodic capacity. Notably, we derive a novel closed-form expression to characterize the distribution of multi-beam interference with varying beam gains. Theoretical analysis and simulation results confirm that the proposed framework achieves a substantially lower outage probability compared to conventional OFDM schemes, with a system capacity improvement exceeding 11.9%