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Publicações

2023

Online Anomaly Explanation: A Case Study on Predictive Maintenance

Autores
Ribeiro, RP; Mastelini, SM; Davari, N; Aminian, E; Veloso, B; Gama, J;

Publicação
MACHINE LEARNING AND PRINCIPLES AND PRACTICE OF KNOWLEDGE DISCOVERY IN DATABASES, ECML PKDD 2022, PT II

Abstract
Predictive Maintenance applications are increasingly complex, with interactions between many components. Black-box models are popular approaches due to their predictive accuracy and are based on deep-learning techniques. This paper presents an architecture that uses an online rule learning algorithm to explain when the black-box model predicts rare events. The system can present global explanations that model the black-box model and local explanations that describe why the black-box model predicts a failure. We evaluate the proposed system using four real-world public transport data sets, presenting illustrative examples of explanations.

2023

PV Hosting Capacity in LV Networks by Combining Customer Voltage Sensitivity and Reliability Analysis

Autores
Mikka Kisuule; Mike Brian Ndawula; Chenghong Gu; Ignacio Hernando-Gil;

Publicação
Energies

Abstract
This paper investigates voltage regulation in low voltage (LV) networks under different loading conditions of a supply network, with increased levels of distributed generation, and in particular with a diverse range of locational solar photovoltaic (PV) penetration. This topic has been researched extensively, with beneficial impacts expected up to a certain point when reverse power flows begin to negatively impact customers connected to the distribution system. In this paper, a voltage-based approach that utilizes novel voltage-based reliability indices is proposed to analyse the risk and reliability of the LV supply feeder, as well as its PV hosting capacity. The proposed indices are directly comparable to results from a probabilistic reliability assessment. The operation of the network is simulated for different PV scenarios to investigate the impacts of increased PV penetration, the location of PV on the feeder, and loading conditions of the MV supply network on the reliability results. It can be seen that all reliability indices improve with increased PV penetration levels when the supply network is heavily loaded and conversely deteriorate when the supply network is lightly loaded. Moreover, bus voltages improve when an on-load tap changer is fitted at the secondary trans-former which leads to better reliability performance as the occurrence and duration of low voltage violations are reduced in all PV scenarios. The approach in this paper is opposed to the conventional reliability assessment, which considers sustained interruptions to customers caused by failure of network components, and thus contributes to a comprehensive analysis of quality of service by considering transient events (i.e., voltage related) in the LV distribution network.

2023

Operating AI systems in the electricity sector under European's AI Act - Insights on compliance costs, profitability frontiers and extraterritorial effects

Autores
Heymann, F; Parginos, K; Bessa, RJ; Galus, M;

Publicação
ENERGY REPORTS

Abstract
Artificial intelligence (AI) brings great potential but also risks to the electricity industry. Following the EU's current regulatory proposal, the EU Regulation for Artificial Intelligence (AI Act), there will be direct, potentially adverse effects on companies of the electricity industry in Europe and beyond, as well as those active in the development of AI systems. In this paper, we develop a replicable framework for estimating compliance costs for different electricity market agents that will need to comply with the numerous requirements the AI Act imposes. The electricity systems of Austria, Greece and Switzerland are used as case-studies. We estimate annual, aggregated costs for electricity market agents ranging from less than one million to almost 200 million Euros per country, depending on compliance costs scenarios. Results suggest that a profit growth of 10% through AI utilization is needed to offset the highest added compliance cost of the AI Act on electricity market agents. Eventually, we further show how to assess the regional differences of these costs added to system operation, providing spatially disaggregated compliance costs estimates that consider the structural differences of the electricity industry within 26 Swiss cantons.

2023

Immersive Learning Environments for Self-regulation of Learning: A Literature Review

Autores
Pedrosa, D; Morgado, L; Beck, D;

Publicação
iLRN

Abstract
Self-regulation of learning (SRL) plays a decisive role in learning success but characterizing learning environments that facilitate development of SRL skills constitutes a great challenge. Given the growing interest in Immersive Learning Environments (ILE), we sought to understand how ILE are built with attention to SRL, via a literature review of pedagogical uses, practices and strategies with ILE that have an explicit focus on SRL. From a final corpus of 25 papers, we collected 134 extracts attesting use of ILE for SRL. We classified and mapped them using the Beck, Morgado & O’Shea framework and its three dimensions of the immersion phenomenon: system, narrative and challenge. There is a predominance of uses of ILE for SRL aligned with Challenge-based immersion: Skill Training, Collaboration, Engagement, and Interactive Manipulation and Exploration. In contrast, uses aligned with System-based immersion (Emphasis, Accessibility, Seeing the Invisible) were not identified. There were few cases of use of Narrative-based immersion. Uses combining the three dimensions of immersive had residual prevalence. We concluded that there is greater tendency in studies of SRL in ILE to enact active roles (aligned with the Challenge dimension of immersion). The low prevalence of Narrative immersion and System immersion evidence gaps in the diversity of pedagogical uses of ILE to develop SRL, which indicate opportunities for research and creation of innovative educational practices.

2023

Real-Time Monitoring of Cement Paste Carbonation with In Situ Optical Fiber Sensors

Autores
da Silva, PM; Mendes, JP; Coelho, LCC; de Almeida, JMMM;

Publicação
CHEMOSENSORS

Abstract
Reinforced concrete structures are prevalent in infrastructure and are of significant economic and social importance to humanity. However, they are prone to decay from cement paste carbonation. pH sensors have been developed to monitor cement paste carbonation, but their adoption by the industry remains limited. This work introduces two new methods for monitoring cement paste carbonation in real time that have been validated through the accelerated carbonation of cement paste samples. Both configurations depart from traditional pH monitoring. In the first configuration, the carbonation depth of a cement paste sample is measured using two CO2 optical fiber sensors. One sensor is positioned on the surface of the sample, while the other is embedded in the middle. As the carbonation depth progresses and reaches the embedded CO2 sensor, the combined response of the sensors changes. In the second configuration, a multimode fiber is embedded within the paste, and its carbonation is monitored by observing the increase in reflected light intensity (1.6-18%) resulting from the formation of CaCO3. Its applicability in naturally occurring carbonation is tested at concentrations of 3.2% CO2, and the influence of water is positively evaluated; thus, this setup is suitable for real-world testing and applications.

2023

Computer Vision, Imaging and Computer Graphics Theory and Applications - 17th International Joint Conference, VISIGRAPP 2022, Virtual Event, February 6-8, 2022, Revised Selected Papers

Autores
de Sousa, AA; Debattista, K; Paljic, A; Ziat, M; Hurter, C; Purchase, HC; Farinella, GM; Radeva, P; Bouatouch, K;

Publicação
VISIGRAPP (Revised Selected Papers)

Abstract

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