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Shen, Y.S. (author), Ersoy, O. (author), Roos, S. (author)Payment channel networks (PCNs) are a promising solution to the blockchain scalability problem. In PCNs, a sender can route a multi-hop payment to a receiver via intermediaries. Yet, Lightning, the only prominent payment channel network, has two major issues when it comes to multi-hop payments. First, the sender decides on the path without...conference paper 2024
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Zhao, Z. (author), Huang, J. (author), Chen, Lydia Y. (author), Roos, S. (author)Generative Adversarial Networks (GANs) are increasingly adopted by the industry to synthesize realistic images using competing generator and discriminator neural networks. Due to data not being centrally available, Multi-Discriminator (MD)-GANs training frameworks employ multiple discriminators that have direct access to the real data....conference paper 2024
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Ersoy, O. (author), Moreno-Sanchez, Pedro (author), Roos, S. (author)The Lightning Network provides almost-instant payments to its parties. In addition to direct payments requiring a shared payment channel, parties can pay each other in the form of multi-hop payments via existing channels. Such multi-hop payments rely on a 2-phase commit protocol to achieve balance security; that is, no honest intermediary...conference paper 2024
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de Vos, M.A. (author), Ishmaev, G. (author), Pouwelse, J.A. (author), Roos, S. (author)Catalyzed by the popularity of blockchain technology, there has recently been a renewed interest in the design, implementation and evaluation of decentralized systems. Most of these systems are intended to be deployed at scale and in heterogeneous environments with real users and unpredictable workloads. Nevertheless, most research in this field...conference paper 2023
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Coesoij, R.A. (author), Musters, F.A. (author), Roos, D. (author), van Velden, T. (author), Spirito, M. (author)In this work we present calibration approaches aimed at mitigating the measurement error in testbenches featuring multiple sensor-nodes and operating over-the-air. Such errors can arise from fluctuations in component responses and mechanical tolerances of the setup. The calibration approaches are detailed for the case of the Antenna Dome...conference paper 2023
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Thai, Sovanna (author), Theodoulis, S.T. (author), Roos, Clément (author), Biannic, Jean Marc (author)This article deals with the control design of a dual-spin projectile concept, characterized by highly nonlinear parameter-dependent and coupled dynamics, and subject to uncertainties and actuator saturations. An open-loop nonlinear model stemming from flight mechanics is first developed. It is subsequently linearized and decomposed into a...journal article 2023
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Huang, J. (author), Zhao, Z. (author), Chen, Lydia Y. (author), Roos, S. (author)Attacks on Federated Learning (FL) can severely reduce the quality of the generated models and limit the usefulness of this emerging learning paradigm that enables on-premise decentralized learning. However, existing untargeted attacks are not practical for many scenarios as they assume that i) the attacker knows every update of benign...conference paper 2023
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Huang, J. (author), Hong, C. (author), Liu, Yang (author), Chen, Lydia Y. (author), Roos, S. (author)Federated learning (FL) enables collaborative learning between parties, called clients, without sharing the original and potentially sensitive data. To ensure fast convergence in the presence of such heterogeneous clients, it is imperative to timely select clients who can effectively contribute to learning. A realistic but overlooked case of...conference paper 2023
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Wei, Zhang (author), Roos, C. (author)We introduce a new variant of Chubanov's method for solving linear homogeneous systems with positive variables. In the Basic Procedure we use a recently introduced cut in combination with Nemirovski's Mirror-Prox method. We show that the cut requires at most (Formula presented.) time, just as Chubanov's cut. In an earlier paper it was shown...journal article 2022
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Sharaf, A.M.S.E. (author), Roos, B. (author), Timmerman, Raissa (author), Kremers, Gert-Jan (author), Bajramovic, Jeffrey John (author), Accardo, A. (author)Microglia are the resident macrophages of the central nervous system and contribute to maintaining brain’s homeostasis. Current 2D “petri-dish” in vitro cell culturing platforms employed for microglia, are unrepresentative of the softness or topography of native brain tissue. This often contributes to changes in microglial morphology, exhibiting...journal article 2022
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Byrenheid, Martin (author), Roos, S. (author), Strufe, Thorsten (author)Due to its high efficiency, routing based on greedy embeddings of rooted spanning trees is a promising approach for dynamic, large-scale networks with restricted topologies. Friend-to-friend (F2F) overlays, one key application of embedding-based routing, aim to prevent disclosure of their participants to malicious members by restricting...conference paper 2022
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Byrenheid, Martin (author), Roos, S. (author), Strufe, Thorsten (author)Routing based on greedy network embeddings enables efficient and privacypreserving routing in overlays where connectivity is restricted to mutually trusted nodes. In previous works, we proposed security enhancements to the embedding and routing procedures to protect against denial-of-service attacks by malicious overlay participants. In this...journal article 2021
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Prabhu Kumble, S. (author), Epema, D.H.J. (author), Roos, S. (author)Lightning, the prevailing solution to Bitcoin's scalability issue, uses onion routing to hide senders and recipients of payments. Yet, the path between the sender and the recipient along which payments are routed is selected such that it is short, cost efficient, and fast. The low degree of randomness in the path selection entails that...conference paper 2021
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Bai, Y. (author), Roos, C. (author)We consider nine elementary problems in optimization. We simply explore the conditions for optimality as known from the duality theory for convex optimization. This yields a quite straightforward solution method for each of these problems. The main contribution of this paper is that we show that even in the harder cases the solution needs...conference paper 2021
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Huang, J. (author), Talbi, Rania (author), Zhao, Z. (author), Boucchenak, Sara (author), Chen, Lydia Y. (author), Roos, S. (author)Federated Learning is an emerging distributed collaborative learning paradigm adopted by many of today's applications, e.g., keyboard prediction and object recognition. Its core principle is to learn from large amount of users data while preserving data privacy by design as collaborative users only need to share the machine learning models...conference paper 2020
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Reef, K.R.G. (author), Roos, P.C. (author), Schuttelaars, H.M. (author), Hulscher, S.J.M.H. (author)Observations of barrier coasts around the world suggest that some systems do not conform to the O'Brien-Jarret law. Here we explain this by investigating how resonance and bottom friction affect the response of tidal inlets to variations in basin geometry. Therefore, we develop a morphodynamic barrier coast model that is based on the...journal article 2020
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Byrenheid, Martin (author), Strufe, Thorsten (author), Roos, S. (author)Current leader election algorithms fail in the presence of Sybil attacks, i.e., one malicious entity inserting many nodes, network dynamics, and restricted knowledge about the graph. However, social overlay networks, i.e., peer-to-peer networks with links corresponding to social relationships, face all of the above challenges. Social overlay...conference paper 2020
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Byrenheid, Martin (author), Strufe, Thorsten (author), Roos, S. (author)Greedy embeddings on rooted spanning trees are the most promising solution to provide sufficiently scalable routing in dynamic networks with restricted topologies, for instance friend-to-friend overlays such as the Dark Freenet and payment channel networks such as Lightning. Yet, they are not deployed in practice, as electing a root and...conference paper 2020
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Ersoy, O. (author), Roos, S. (author), Erkin, Z. (author)Payment channel networks like Bitcoin’s Lightning network are an auspicious approach for realizing high transaction throughput and almost-instant confirmations in blockchain networks. However, the ability to successfully conduct payments in such networks relies on the willingness of participants to lock collateral in the network. In Lightning...conference paper 2020
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Byrenheid, Martin (author), Roos, S. (author), Strufe, Thorsten (author)Nodes in route-restricted overlays have an im-mutable set of neighbors, explicitly specified by their users. Pop-ular examples include payment networks such as the Lightningnetwork as well as social overlays such as the Dark Freenet.Routing algorithms are central to such overlays as they enablecommunication between nodes that are not directly...conference paper 2019