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Publicações

Publicações por CSE

2023

Temporal variability of gamma radiation and aerosol concentration over the North Atlantic ocean

Autores
Dias, N; Amaral, G; Almeida, C; Ferreira, A; Camilo, A; Silva, E; Barbosa, S;

Publicação

Abstract
<p>Gamma radiation measured over the ocean is mainly due to airborne radionuclides, as gamma emission by radon degassing from the ocean is negligible. Airborne gamma-emitting elements include radon progeny (Pb-2114, Bi-214, Pb-210) and cosmogenic radionuclides such as Be-7. Radon progeny attaches readily to aerosols, thus the fate of gamma-emitting radon progeny, after its formation by radioactive decay from radon, is expected to be closely linked to that of aerosols.</p> <p>Gamma radiation measurements over the Atlantic Ocean were made on board the ship-rigged sailing ship NRP Sagres in the framework of project SAIL (Space-Atmosphere-Ocean Interactions in the marine boundary Layer). The measurements were performed continuously with a NaI(Tl) scintillator counting all gamma rays from 475 keV to 3 MeV.  </p> <p>The counts from the sensor were recorded every 1 second into a computer system which had his time reference corrected by a GNSS pulse per second (PPS) signal. The GNSS was also used to precisely position the ship. The measurements were performed over the Atlantic ocean from January to May 2020, along the ship’s round trip from Lisboa - Cape Verde – Rio de Janeiro – Buenos Aires – Cape Town – Cape Verde - Lisboa.</p> <p>The results show that the gamma radiation time series displays considerable higher counts and larger variability in January compared to the remaining period. Reanalysis data also indicate higher aerosol concentration. This work investigates in detail the association between the temporal evolution of the gamma radiation measurements obtained from the SAIL campaign over the Atlantic Ocean and co-located total aerosol concentration at 550 nm obtained every 3 hours from EAC4(ECMWF Atmospheric Composition Reanalysis 4) data.</p>

2023

How Much Presence is Enough? Qualitative Scales for Interpreting the Igroup Presence Questionnaire Score

Autores
Melo, M; Gontalves, G; Vasconcelos-Raposo, J; Bessa, M;

Publicação
IEEE ACCESS

Abstract
Presence is often used to evaluate Virtual Reality (VR) applications. However, the raw scores are hard to interpret and need to be compared to other data to be meaningful. This paper leverages a database of 1909 responses to the Igroup Presence Questionnaire (IPQ) in different contexts to put forward a scale that qualitatively interprets raw Presence scores for VR experiences. The qualitative grading encompasses the acceptability dimension and analogous academic grading scales ranging from A to F and the adjective of such scores in a scale from Excellent to Unacceptable. Furthermore, the qualitative grading system encompasses Presence and its subscales Spatial Presence, Involvement, and Experienced Realism as defined by the IPQ. Adopting this grading system, supported by a robust dataset of Presence scores, enables practitioners to evaluate and interpret individual IPQ scores, allowing them to gain insights regarding the evaluated applications' effectiveness.

2023

AGE: Automatic Performance Evaluation of API Gateways

Autores
Moreira, P; Ribeiro, A; Silva, JMC;

Publicação
IEEE Symposium on Computers and Communications, ISCC 2023, Gammarth, Tunisia, July 9-12, 2023

Abstract
The increasing use of microservices architectures has been accompanied by the profusion of tools for their design and operation. One relevant tool is API Gateways, which work as a proxy for microservices, hiding their internal APIs, providing load balancing, and multiple encoding support. Particularly in cloud environments, where the inherent flexibility allows on-demand resource deployment, API Gateways play a key role in seeking quality of service. Although multiple solutions are currently available, a comparative performance assessment under real workloads to support selecting the more suitable one for a specific service is time-consuming. In this way, the present work introduces AGE, a service capable of automatically deploying multiple API Gateways scenarios and providing a simple comparative performance indicator for a defined workload and infrastructure. The designed proof of concept shows that AGE can speed up API Gateway deployment and testing in multiple environments. © 2023 IEEE.

2023

HCI-E2-2023: Second IFIP WG 2.7/13.4 Workshop on HCI Engineering Education

Autores
Campos, JC; Nigay, L; Dix, AJ; Dittmar, A; Barbosa, SDJ; Spano, LD;

Publicação
Human-Computer Interaction - INTERACT 2023 - 19th IFIP TC13 International Conference, York, UK, August 28 - September 1, 2023, Proceedings, Part IV

Abstract
This second workshop on HCI Engineering Education aims at carrying forward work on identifying, examining, structuring, and sharing educational resources and approaches to support the process of teaching/learning Human-Computer Interaction (HCI) Engineering. The widening range of available interaction technologies and their applications in increasingly varied contexts (private or professional) underlines the importance of teaching HCI Engineering but also the difficulty of taking into account changes and developments in this field in often static university curricula. Besides, as these technologies are taught in diverse curricula (ranging from Human Factors and Psychology to hardcore Computer Science), we are interested in what the best approaches and best practices are to integrate HCI Engineering topics in the curricula of programs in Software Engineering, Computer Science, Human-computer Interaction, Psychology, Design, etc. The workshop is proposed on behalf of the IFIP Working Group 2.7/13.4 on User Interface Engineering. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.

2023

MRVs: Enforcing Numeric Invariants in Parallel Updates to Hotspots with Randomized Splitting

Autores
Faria, N; Pereira, J;

Publicação
Proc. ACM Manag. Data

Abstract
Performance of transactional systems is degraded by update hotspots as conflicts lead to waiting and wasted work. This is particularly challenging in emerging large-scale database systems, as latency increases the probability of conflicts, state-of-the-art lock-based mitigations are not available, and most alternatives provide only weak consistency and cannot enforce lower bound invariants. We address this challenge with Multi-Record Values (MRVs), a technique that can be layered on existing database systems and that uses randomization to split and access numeric values in multiple records such that the probability of conflict can be made arbitrarily small. The only coordination needed is the underlying transactional system, meaning it retains existing isolation guarantees. The proposal is tested on five different systems ranging from DBx1000 (scale-up) to MySQL GR and a cloud-native NewSQL system (scale-out). The experiments explore design and configuration trade-offs and, with the TPC-C and STAMP Vacation benchmarks, demonstrate improved throughput and reduced abort rates when compared to alternatives.

2023

Prototyping with the IVY Workbench: Bridging Formal Methods and User-Centred Design

Autores
da Costa, RB; Campos, JC;

Publicação
Human-Computer Interaction - INTERACT 2023 - 19th IFIP TC13 International Conference, York, UK, August 28 - September 1, 2023, Proceedings, Part II

Abstract
The IVY workbench is a model-based tool for the formal modelling and verification of interactive systems. The tool uses model checking to carry out the verification step. The goal is not to replace, but to complement more exploratory and iterative user-centred design approaches. However, the need for formal and rigorous modelling and reasoning raises challenges for the integration of both approaches. This paper presents a new plugin that aims to provide support for the integration of the formal methods based analysis supported by the tool, with user-centred design. The plugin is described, and an initial validation of its functionalities presented. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.

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