7 Search Results for "Oliveira, Tiago"

Document
DOI: 10.4230/OASIcs.SpaceCHI.2025.26
Movement in Low Gravity (MoLo) – LUNA: Biomechanical Modelling to Mitigate Lunar Surface Operation Risks

Authors: David Andrew Green

Published in: OASIcs, Volume 130, Advancing Human-Computer Interaction for Space Exploration (SpaceCHI 2025)

Abstract
The Artemis programme seeks to develop and test concepts, hardware and approaches to support long term habitation of the Lunar surface, and future missions to Mars. In preparation for the Artemis missions determination of tasks to be performed, the functional requirements of such tasks and as mission duration extends whether physiological deconditioning becomes functionally significant, compromising the crew member’s ability to perform critical tasks on the surface, and/or upon return to earth [MoLo-LUNA – leveraging the Molo programme (and several other activities) - could become a key supporting activity for LUNA incl. validation of the Puppeteer offloading system itself via creation of a complementary MoLo-LUNA-LAB. Furthermore, the MoLo-LUNA programme could become a key facilitator of simulator suit instrumentation/definition, broader astronaut training activities and mission architecture development – including Artemis mission simulations. By employing a Puppeteer system external to the LUNA chamber hall it will optimise utilisation and cost-effectiveness of LUNA, and as such represents a critical service to future LUNA stakeholders. Furthermore, MoLo-LUNA would generate a unique data set that can be leveraged to predict de-conditioning on the Lunar surface - and thereby optimise functionality, and minimise mission risk – including informing the need for, and prescription of exercise countermeasures on the Lunar Surface and in transit. Thus, MoLo-LUNA offers a unique opportunity to place LUNA, and ESA as a key ongoing provider of evidence to define, optimise and support crew Artemis surface missions.
Cite as

David Andrew Green. Movement in Low Gravity (MoLo) – LUNA: Biomechanical Modelling to Mitigate Lunar Surface Operation Risks. In Advancing Human-Computer Interaction for Space Exploration (SpaceCHI 2025). Open Access Series in Informatics (OASIcs), Volume 130, pp. 26:1-26:11, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{green:OASIcs.SpaceCHI.2025.26,
  author =	{Green, David Andrew},
  title =	{{Movement in Low Gravity (MoLo) – LUNA: Biomechanical Modelling to Mitigate Lunar Surface Operation Risks}},
  booktitle =	{Advancing Human-Computer Interaction for Space Exploration (SpaceCHI 2025)},
  pages =	{26:1--26:11},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-384-3},
  ISSN =	{2190-6807},
  year =	{2025},
  volume =	{130},
  editor =	{Bensch, Leonie and Nilsson, Tommy and Nisser, Martin and Pataranutaporn, Pat and Schmidt, Albrecht and Sumini, Valentina},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.SpaceCHI.2025.26},
  URN =		{urn:nbn:de:0030-drops-240166},
  doi =		{10.4230/OASIcs.SpaceCHI.2025.26},
  annote =	{Keywords: Locomotion, hypogravity, modelling, Lunar}
}
Document
DOI: 10.4230/OASIcs.NG-RES.2025.5
SP-IMPact: A Framework for Static Partitioning Interference Mitigation and Performance Analysis

Authors: Diogo Costa, Gonçalo Moreira, Afonso Oliveira, José Martins, and Sandro Pinto

Published in: OASIcs, Volume 128, Sixth Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2025)

Abstract
Modern embedded systems are evolving toward complex, heterogeneous architectures to accommodate increasingly demanding applications. Driven by industry SWAP-C (Size, Weight, Power, and Cost) constraints, this shift has led to the consolidation of multiple systems onto single hardware platforms. Static Partitioning Hypervisors (SPHs) offer a promising solution to partition hardware resources and provide spatial isolation between critical workloads. However, shared hardware resources like the Last-Level Cache (LLC) and system bus can introduce significant temporal interference between virtual machines (VMs), negatively impacting performance and predictability. Over the past decade, academia and industry have focused on developing interference mitigation techniques, such as cache partitioning and memory bandwidth reservation. Configuring these techniques, however, is complex and time-consuming. Cache partitioning requires careful balancing of cache sections across VMs, while memory bandwidth reservation requires tuning bandwidth budgets and periods. With numerous possible configurations, testing all combinations is impractical and often leads to suboptimal configurations. Moreover, there is a gap in understanding how these techniques interact, as their combined use can result in compounded or conflicting effects on system performance. Static analysis solutions that estimate worst-case execution times (WCET) and upper bounds on execution times provide some guidance for configuring interference mitigation techniques. While useful in identifying potential interference effects, these tools often fail to capture the full complexity of modern multi-core systems, as they typically focus on a limited set of shared resources and neglect other sources of contention, such as IOMMUs and interrupt controllers. To address these challenges, we introduce SP-IMPact, an open-source framework designed to analyze and guide the configuration of interference mitigation techniques, through the deployment of diverse VM configurations and setups, and assessment of hardware-level contention (leveraging SPHs). It supports two mitigation techniques: (i) cache coloring and (ii) memory bandwidth reservation, while also evaluating the interactions between these techniques and their cumulative impact on system performance. By providing insights on real hardware platforms, SP-IMPact helps to optimize the configuration of these techniques in mixed-criticality systems, ensuring both performance and predictability.
Cite as

Diogo Costa, Gonçalo Moreira, Afonso Oliveira, José Martins, and Sandro Pinto. SP-IMPact: A Framework for Static Partitioning Interference Mitigation and Performance Analysis. In Sixth Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2025). Open Access Series in Informatics (OASIcs), Volume 128, pp. 5:1-5:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{costa_et_al:OASIcs.NG-RES.2025.5,
  author =	{Costa, Diogo and Moreira, Gon\c{c}alo and Oliveira, Afonso and Martins, Jos\'{e} and Pinto, Sandro},
  title =	{{SP-IMPact: A Framework for Static Partitioning Interference Mitigation and Performance Analysis}},
  booktitle =	{Sixth Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2025)},
  pages =	{5:1--5:15},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-366-9},
  ISSN =	{2190-6807},
  year =	{2025},
  volume =	{128},
  editor =	{Yomsi, Patrick Meumeu and Wildermann, Stefan},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.NG-RES.2025.5},
  URN =		{urn:nbn:de:0030-drops-229911},
  doi =		{10.4230/OASIcs.NG-RES.2025.5},
  annote =	{Keywords: Virtualization, Contention, Multi-core Interference, Mixed-Criticality Systems, Arm}
}
Document
DOI: 10.4230/OASIcs.NG-RES.2025.4
H-MBR: Hypervisor-Level Memory Bandwidth Reservation for Mixed Criticality Systems

Authors: Afonso Oliveira, Diogo Costa, Gonçalo Moreira, José Martins, and Sandro Pinto

Published in: OASIcs, Volume 128, Sixth Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2025)

Abstract
Recent advancements in fields such as automotive and aerospace have driven a growing demand for robust computational resources. Applications that were once designed for basic Microcontroller Units (MCUs) are now deployed on highly heterogeneous System-on-Chip (SoC) platforms. While these platforms deliver the necessary computational performance, they also present challenges related to resource sharing and predictability. These challenges are particularly pronounced when consolidating safety-critical and non-safety-critical systems, the so-called Mixed-Criticality Systems (MCS) to adhere to strict Size, Weight, Power, and Cost (SWaP-C) requirements. MCS consolidation on shared platforms requires stringent spatial and temporal isolation to comply with functional safety standards (e.g., ISO 26262). Virtualization, mainly leveraged by hypervisors, is a key technology that ensures spatial isolation across multiple OSes and applications; however ensuring temporal isolation remains challenging due to contention on shared resources, such as main memory, caches, and system buses, which impacts real-time performance and predictability. To mitigate this problem, several strategies (e.g., cache coloring and memory bandwidth reservation) have been proposed. Although cache coloring is typically implemented on state-of-the-art hypervisors, memory bandwidth reservation approaches are commonly implemented at the Linux kernel level or rely on dedicated hardware and typically do not consider the concept of Virtual Machines that can run different OSes. To fill the gap between current memory bandwidth reservation solutions and the deployment of MCSs that operate on a hypervisor, this work introduces H-MBR, an open-source VM-centric memory bandwidth reservation mechanism. H-MBR features (i) VM-centric bandwidth reservation, (ii) OS and platform agnosticism, and (iii) reduced overhead. Empirical results evidenced no overhead on non-regulated workloads, and negligible overhead (<1%) for regulated workloads for regulation periods of 2 µs or higher.
Cite as

Afonso Oliveira, Diogo Costa, Gonçalo Moreira, José Martins, and Sandro Pinto. H-MBR: Hypervisor-Level Memory Bandwidth Reservation for Mixed Criticality Systems. In Sixth Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2025). Open Access Series in Informatics (OASIcs), Volume 128, pp. 4:1-4:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{oliveira_et_al:OASIcs.NG-RES.2025.4,
  author =	{Oliveira, Afonso and Costa, Diogo and Moreira, Gon\c{c}alo and Martins, Jos\'{e} and Pinto, Sandro},
  title =	{{H-MBR: Hypervisor-Level Memory Bandwidth Reservation for Mixed Criticality Systems}},
  booktitle =	{Sixth Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2025)},
  pages =	{4:1--4:15},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-366-9},
  ISSN =	{2190-6807},
  year =	{2025},
  volume =	{128},
  editor =	{Yomsi, Patrick Meumeu and Wildermann, Stefan},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.NG-RES.2025.4},
  URN =		{urn:nbn:de:0030-drops-229905},
  doi =		{10.4230/OASIcs.NG-RES.2025.4},
  annote =	{Keywords: Virtualization, Multi-core Interference, Mixed-Criticality Systems, Arm, Memory Bandwidth Reservation}
}
Document
DOI: 10.4230/OASIcs.SLATE.2021.14
Using Machine Learning for Vulnerability Detection and Classification

Authors: Tiago Baptista, Nuno Oliveira, and Pedro Rangel Henriques

Published in: OASIcs, Volume 94, 10th Symposium on Languages, Applications and Technologies (SLATE 2021)

Abstract
The work described in this paper aims at developing a machine learning based tool for automatic identification of vulnerabilities on programs (source, high level code), that uses an abstract syntax tree representation. It is based on FastScan, using code2seq approach. Fastscan is a recently developed system aimed capable of detecting vulnerabilities in source code using machine learning techniques. Nevertheless, FastScan is not able of identifying the vulnerability type. In the presented work the main goal is to go further and develop a method to identify specific types of vulnerabilities. As will be shown, the goal will be achieved by optimizing the model’s hyperparameters, changing the method of preprocessing the input data and developing an architecture that brings together multiple models to predict different specific vulnerabilities. The preliminary results obtained from the training stage, are very promising. The best f1 metric obtained is 93% resulting in a precision of 90% and accuracy of 85%, according to the performed tests and regarding a trained model to predict vulnerabilities of the injection type.
Cite as

Tiago Baptista, Nuno Oliveira, and Pedro Rangel Henriques. Using Machine Learning for Vulnerability Detection and Classification. In 10th Symposium on Languages, Applications and Technologies (SLATE 2021). Open Access Series in Informatics (OASIcs), Volume 94, pp. 14:1-14:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)

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@InProceedings{baptista_et_al:OASIcs.SLATE.2021.14,
  author =	{Baptista, Tiago and Oliveira, Nuno and Henriques, Pedro Rangel},
  title =	{{Using Machine Learning for Vulnerability Detection and Classification}},
  booktitle =	{10th Symposium on Languages, Applications and Technologies (SLATE 2021)},
  pages =	{14:1--14:14},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-202-0},
  ISSN =	{2190-6807},
  year =	{2021},
  volume =	{94},
  editor =	{Queir\'{o}s, Ricardo and Pinto, M\'{a}rio and Sim\~{o}es, Alberto and Portela, Filipe and Pereira, Maria Jo\~{a}o},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.SLATE.2021.14},
  URN =		{urn:nbn:de:0030-drops-144315},
  doi =		{10.4230/OASIcs.SLATE.2021.14},
  annote =	{Keywords: Vulnerability Detection, Source Code Analysis, Machine Learning}
}
Document
DOI: 10.4230/OASIcs.SLATE.2020.9
Exploring Different Methods for Solving Analogies with Portuguese Word Embeddings

Authors: Tiago Sousa, Hugo Gonçalo Oliveira, and Ana Alves

Published in: OASIcs, Volume 83, 9th Symposium on Languages, Applications and Technologies (SLATE 2020)

Abstract
A common way of assessing static word embeddings is to use them for solving analogies of the kind "what is to king as man is to woman?". For this purpose, the vector offset method (king - man + woman = queen), also known as 3CosAdd, has been effectively used for solving analogies and assessing different models of word embeddings in different languages. However, some researchers pointed out that this method is not the most effective for this purpose. Following this, we tested alternative analogy solving methods (3CosMul, 3CosAvg, LRCos) in Portuguese word embeddings and confirmed the previous statement. Specifically, those methods are used to answer the Portuguese version of the Google Analogy Test, dubbed LX-4WAnalogies, which covers syntactic and semantic analogies of different kinds. We discuss the accuracy of different methods applied to different models of embeddings and take some conclusions. Indeed, all methods outperform 3CosAdd, and the best performance is consistently achieved with LRCos, in GloVe.
Cite as

Tiago Sousa, Hugo Gonçalo Oliveira, and Ana Alves. Exploring Different Methods for Solving Analogies with Portuguese Word Embeddings. In 9th Symposium on Languages, Applications and Technologies (SLATE 2020). Open Access Series in Informatics (OASIcs), Volume 83, pp. 9:1-9:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)

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@InProceedings{sousa_et_al:OASIcs.SLATE.2020.9,
  author =	{Sousa, Tiago and Gon\c{c}alo Oliveira, Hugo and Alves, Ana},
  title =	{{Exploring Different Methods for Solving Analogies with Portuguese Word Embeddings}},
  booktitle =	{9th Symposium on Languages, Applications and Technologies (SLATE 2020)},
  pages =	{9:1--9:14},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-165-8},
  ISSN =	{2190-6807},
  year =	{2020},
  volume =	{83},
  editor =	{Sim\~{o}es, Alberto and Henriques, Pedro Rangel and Queir\'{o}s, Ricardo},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.SLATE.2020.9},
  URN =		{urn:nbn:de:0030-drops-130229},
  doi =		{10.4230/OASIcs.SLATE.2020.9},
  annote =	{Keywords: analogies, word embeddings, semantic relations, syntactic relations, Portuguese}
}
Document
DOI: 10.4230/LIPIcs.OPODIS.2016.30
Exploring Key-Value Stores in Multi-Writer Byzantine-Resilient Register Emulations

Authors: Tiago Oliveira, Ricardo Mendes, and Alysson Bessani

Published in: LIPIcs, Volume 70, 20th International Conference on Principles of Distributed Systems (OPODIS 2016)

Abstract
Resilient register emulation is a fundamental technique to implement dependable storage and distributed systems. In data-centric models, where servers are modeled as fail-prone base objects, classical solutions achieve resilience by using fault-tolerant quorums of read-write registers or read-modify-write objects. Recently, this model has attracted renewed interest due to the popularity of cloud storage providers (e.g., Amazon S3), that can be modeled as key-value stores (KVSs) and combined for providing secure and dependable multi-cloud storage services. In this paper we present three novel wait-free multi-writer multi-reader regular register emulations on top of Byzantine-prone KVSs. We implemented and evaluated these constructions using five existing cloud storage services and show that their performance matches or surpasses existing data-centric register emulations.
Cite as

Tiago Oliveira, Ricardo Mendes, and Alysson Bessani. Exploring Key-Value Stores in Multi-Writer Byzantine-Resilient Register Emulations. In 20th International Conference on Principles of Distributed Systems (OPODIS 2016). Leibniz International Proceedings in Informatics (LIPIcs), Volume 70, pp. 30:1-30:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)

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@InProceedings{oliveira_et_al:LIPIcs.OPODIS.2016.30,
  author =	{Oliveira, Tiago and Mendes, Ricardo and Bessani, Alysson},
  title =	{{Exploring Key-Value Stores in Multi-Writer Byzantine-Resilient Register Emulations}},
  booktitle =	{20th International Conference on Principles of Distributed Systems (OPODIS 2016)},
  pages =	{30:1--30:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-031-6},
  ISSN =	{1868-8969},
  year =	{2017},
  volume =	{70},
  editor =	{Fatourou, Panagiota and Jim\'{e}nez, Ernesto and Pedone, Fernando},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.OPODIS.2016.30},
  URN =		{urn:nbn:de:0030-drops-70999},
  doi =		{10.4230/LIPIcs.OPODIS.2016.30},
  annote =	{Keywords: Byzantine fault tolerance, register emulation, multi-writer, key-value store, data-centric algorithms}
}
Document
DOI: 10.4230/OASIcs.ICCSW.2015.62
Representing Temporal Patterns in Computer-Interpretable Clinical Guidelines

Authors: António Silva, Tiago Oliveira, Paulo Novais, and José Neves

Published in: OASIcs, Volume 49, 2015 Imperial College Computing Student Workshop (ICCSW 2015)

Abstract
Computer-Interpretable Guidelines (CIGs) as machine-readable versions of clinical protocols have to provide appropriate constructs for the representation of different aspects of medical knowledge, namely administrative information, workflows of procedures, clinical constraints and temporal constraints. This work focuses on the latter, by aiming to develop a comprehensive representation of temporal constraints for machine readable formats of clinical protocols and provide a proper execution engine that deals with different time patterns and constraints placed on them. A model for the representation of time is presented for the CompGuide ontology in Ontology Web language (OWL) along with a comparison with the available formalisms in this field.
Cite as

António Silva, Tiago Oliveira, Paulo Novais, and José Neves. Representing Temporal Patterns in Computer-Interpretable Clinical Guidelines. In 2015 Imperial College Computing Student Workshop (ICCSW 2015). Open Access Series in Informatics (OASIcs), Volume 49, pp. 62-69, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2015)

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@InProceedings{silva_et_al:OASIcs.ICCSW.2015.62,
  author =	{Silva, Ant\'{o}nio and Oliveira, Tiago and Novais, Paulo and Neves, Jos\'{e}},
  title =	{{Representing Temporal Patterns in Computer-Interpretable Clinical Guidelines}},
  booktitle =	{2015 Imperial College Computing Student Workshop (ICCSW 2015)},
  pages =	{62--69},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-000-2},
  ISSN =	{2190-6807},
  year =	{2015},
  volume =	{49},
  editor =	{Schulz, Claudia and Liew, Daniel},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ICCSW.2015.62},
  URN =		{urn:nbn:de:0030-drops-54827},
  doi =		{10.4230/OASIcs.ICCSW.2015.62},
  annote =	{Keywords: Computer-Interpretable Guidelines, Temporal Constraints, Clinical Decision Support, Ontologies}
}
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