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Publicações

2023

Soteria: Preserving Privacy in Distributed Machine Learning

Autores
Brito, C; Ferreira, P; Portela, B; Oliveira, R; Paulo, J;

Publicação
38TH ANNUAL ACM SYMPOSIUM ON APPLIED COMPUTING, SAC 2023

Abstract
We propose Soteria, a system for distributed privacy-preserving Machine Learning (ML) that leverages Trusted Execution Environments (e.g. Intel SGX) to run code in isolated containers (enclaves). Unlike previous work, where all ML-related computation is performed at trusted enclaves, we introduce a hybrid scheme, combining computation done inside and outside these enclaves. The conducted experimental evaluation validates that our approach reduces the runtime of ML algorithms by up to 41%, when compared to previous related work. Our protocol is accompanied by a security proof, as well as a discussion regarding resilience against a wide spectrum of ML attacks.

2023

Negative network effects and asymmetric pure price equilibria

Autores
Soeiro, R; Pinto, AA;

Publicação
PORTUGUESE ECONOMIC JOURNAL

Abstract
We show that in finite settings with identical firms and consumers, asymmetric pure price equilibria with positive profits exist. We consider a price competition duopoly for a homogeneous product. Demand stems from a second-stage consumption game at posted prices, with consumers' behavior impacted by negative network effects. We characterize equilibrium prices and demand. In all subgame-perfect pure price equilibria, both firms have positive profits, and in some, firms charge different prices.

2023

ATLANTIS Coastal Testbed: A near-real playground for the testing and validation of robotics for O&M

Autores
Pinto, AM; Marques, JVA; Abreu, N; Campos, DF; Pereira, MI; Gonçalves, E; Campos, HJ; Pereira, P; Neves, F; Matos, A; Govindaraj, S; Durand, L;

Publicação
OCEANS 2023 - LIMERICK

Abstract
The demonstration of robotic technologies in real environments is essential for technology developers and end-users to fully showcase the benefits of theirs solutions, and contributes to the promotion of the transition of inspection and maintenance methodologies towards automated robotic strategies. However, before allowing technologies to be demonstrated in real, operating offshore wind-farms, there is a need to de-risk the technology, to ensure its safe operation offshore. As part of the ATLANTIS project, a pioneer pilot infrastructure, the ATLANTIS Test Centre, was installed in Viana do Castelo, Portugal. This infrastructure will allow the demonstration of key enabling robotic technologies for offshore inspection and maintenance. The Test Centre is composed of two distinct testbeds, and a supervisory control centre, enabling the de-risking, testing, validation and demonstration of technologies, in both near-real and real environments. This paper presents the details of the Coastal Testbed of the ATLANTIS Test Centre, from implementation to available resources and infrastructures and environment details.

2023

Predicting Hard Disk Drive faults, failures and associated misbehavior's

Autores
Harrison, C; Balu, H; Dutra, I;

Publicação
2023 IEEE INTERNATIONAL PARALLEL AND DISTRIBUTED PROCESSING SYMPOSIUM WORKSHOPS, IPDPSW

Abstract
Magnetic hard disk drives continue to be heavily used to store global information. However, due to the physical characteristics these components fatigue and fail, sometimes in unexpected ways. A failing hard disk can cause problems to a group of hard disks and result in suboptimal performance which impacts cloud providers. To address failures, redundancies are put in place, but these redundancies have a high cost. Utilizing Machine learning we identify predictive failure features within a hard disk vendor's Hard Disk Drive Model line which can be used as an early failure prediction method which may be used to reduce redundancies in cloud storage infrastructures.

2023

Trajectory-Aware Rate Adaptation for Flying Networks

Autores
Queirós, R; Ruela, J; Fontes, H; Campos, R;

Publicação
Simulation Tools and Techniques - 15th EAI International Conference, SIMUtools 2023, Seville, Spain, December 14-15, 2023, Proceedings

Abstract

2023

First VLTI/GRAVITY Observations of HIP 65426 b: Evidence for a Low or Moderate Orbital Eccentricity

Autores
Blunt, S; Balmer, WO; Wang, JJ; Lacour, S; Petrus, S; Bourdarot, G; Kammerer, J; Pourré, N; Rickman, E; Shangguan, J; Winterhalder, T; Abuter, R; Amorim, A; Asensio Torres, R; Benisty, M; Berger, JP; Beust, H; Boccaletti, A; Bohn, A; Bonnefoy, M; Bonnet, H; Brandner, W; Cantalloube, F; Caselli, P; Charnay, B; Chauvin, G; Chavez, A; Choquet, E; Christiaens, V; Clénet, Y; du Foresto, VC; Cridland, A; Dembet, R; Drescher, A; Duvert, G; Eckart, A; Eisenhauer, F; Feuchtgruber, H; Garcia, P; Lopez, RG; Gendron, E; Genzel, R; Gillessen, S; Girard, JH; Haubois, X; Heissel, G; Henning, T; Hinkley, S; Hippler, S; Horrobin, M; Houllé, M; Hubert, Z; Jocou, L; Keppler, M; Kervella, P; Kreidberg, L; Lagrange, AM; Lapeyrère, V; Le Bouquin, JB; Leña, P; Lutz, D; Maire, AL; Mang, F; Marleau, GD; Mérand, A; Mollière, P; Monnier, JD; Mordasini, C; Mouillet, D; Nasedkin, E; Nowak, M; Ott, T; Otten, GPPL; Paladini, C; Paumard, T; Perraut, K; Perrin, G; Pfuhl, O; Pueyo, L; Rameau, J; Rodet, L; Rustamkulov, Z; Shimizu, T; Sing, D; Stolker, T; Straubmeier, C; Sturm, E; Tacconi, LJ; van Dishoeck, EF; Vigan, A; Vincent, F; Ward Duong, K; Widmann, F; Wieprecht, E; Wiezorrek, E; Woillez, J; Yazici, S; Young, A;

Publicação
ASTRONOMICAL JOURNAL

Abstract
Giant exoplanets have been directly imaged over orders of magnitude of orbital separations, prompting theoretical and observational investigations of their formation pathways. In this paper, we present new VLTI/GRAVITY astrometric data of HIP 65426 b, a cold, giant exoplanet which is a particular challenge for most formation theories at a projected separation of 92 au from its primary. Leveraging GRAVITY's astrometric precision, we present an updated eccentricity posterior that disfavors large eccentricities. The eccentricity posterior is still prior dependent, and we extensively interpret and discuss the limits of the posterior constraints presented here. We also perform updated spectral comparisons with self-consistent forward-modeled spectra, finding a best-fit ExoREM model with solar metallicity and C/O = 0.6. An important caveat is that it is difficult to estimate robust errors on these values, which are subject to interpolation errors as well as potentially missing model physics. Taken together, the orbital and atmospheric constraints paint a preliminary picture of formation inconsistent with scattering after disk dispersal. Further work is needed to validate this interpretation. Analysis code used to perform this work is available on GitHub: https://github.com/sblunt/hip65426.

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