2025
Authors
Mazarei, A; Sousa, R; Mendes Moreira, J; Molchanov, S; Ferreira, HM;
Publication
INTERNATIONAL JOURNAL OF DATA SCIENCE AND ANALYTICS
Abstract
Outlier detection is a widely used technique for identifying anomalous or exceptional events across various contexts. It has proven to be valuable in applications like fault detection, fraud detection, and real-time monitoring systems. Detecting outliers in real time is crucial in several industries, such as financial fraud detection and quality control in manufacturing processes. In the context of big data, the amount of data generated is enormous, and traditional batch mode methods are not practical since the entire dataset is not available. The limited computational resources further compound this issue. Boxplot is a widely used batch mode algorithm for outlier detection that involves several derivations. However, the lack of an incremental closed form for statistical calculations during boxplot construction poses considerable challenges for its application within the realm of big data. We propose an incremental/online version of the boxplot algorithm to address these challenges. Our proposed algorithm is based on an approximation approach that involves numerical integration of the histogram and calculation of the cumulative distribution function. This approach is independent of the dataset's distribution, making it effective for all types of distributions, whether skewed or not. To assess the efficacy of the proposed algorithm, we conducted tests using simulated datasets featuring varying degrees of skewness. Additionally, we applied the algorithm to a real-world dataset concerning software fault detection, which posed a considerable challenge. The experimental results underscored the robust performance of our proposed algorithm, highlighting its efficacy comparable to batch mode methods that access the entire dataset. Our online boxplot method, leveraging dataset distribution to define whiskers, consistently achieved exceptional outlier detection results. Notably, our algorithm demonstrated computational efficiency, maintaining constant memory usage with minimal hyperparameter tuning.
2025
Authors
Barisic, A; Cunha, J; Ruchkin, I; Moreira, A; Araújo, J; Challenger, M; Savic, D; Amaral, V;
Publication
SUSTAINABLE COMPUTING-INFORMATICS & SYSTEMS
Abstract
Supporting sustainability through modelling and analysis has become an active area of research in Software Engineering. Therefore, it is important and timely to survey the current state of the art in sustainability in Cyber-Physical Systems (CPS), one of the most rapidly evolving classes of complex software systems. This work presents the findings of a Systematic Mapping Study (SMS) that aims to identify key primary studies reporting on CPS modelling approaches that address sustainability over the last 10 years. Our literature search retrieved 2209 papers, of which 104 primary studies were deemed relevant fora detailed characterisation. These studies were analysed based on nine research questions designed to extract information on sustainability attributes, methods, models/meta-models, metrics, processes, and tools used to improve the sustainability of CPS. These questions also aimed to gather data on domain-specific modelling approaches and relevant application domains. The final results report findings for each of our questions, highlight interesting correlations among them, and identify literature gaps worth investigating in the near future.
2025
Authors
Silva, M; Faria, JP;
Publication
Proceedings of the 20th International Conference on Evaluation of Novel Approaches to Software Engineering, ENASE 2025, Porto, Portugal, April 4-6, 2025.
Abstract
2025
Authors
Monteiro, AC; Carvalhais, M; Torres, R;
Publication
ADVANCES IN DESIGN, MUSIC AND ARTS III, EIMAD 2024, VOL 1
Abstract
The interaction between code and language shapes emergence and innovation in computational systems, turning them not merely into a series of connected structures but into narrative spaces. Interactive Digital Narratives (IDNs) are characterized by a tension between the control exerted by the system to engage readers and the autonomy that readers desire over the narrative's direction. This results in a ludic paradox, where the role of the narrative system is to enable and facilitate play while simultaneously being capable of communicating the outcomes of the readers' actions. On the other hand, the reader must be able to participate actively by playing along the system's rules. Based on the notion of interpassivity, which refers to the delegation of the cognitive activity to the object, thus transforming the reader into a passive observer of the system's interactions, this paper aims to explore the interplay between interpassivity and interactivity. As we navigate IDNs, we engage with narratives that challenge and empower readers, that create immersive and enriching experiences, and transform their relationships with the computational system. This contributes to understanding the pleasure of playing and the reader's role. Based on the premise that readers can derive pleasure from automation but also yearn for control over the narrative, we can investigate the playful interaction between humans and machines. This paper will analyze Emissaries (2015-2017), defined by its creator, Ian Cheng, as a video game that plays itself, and where the reader can seemingly only visualize the work. In this case study, we will look for narrative mechanics and the specificity of the medium in which the IDN is instantiated. We will discuss how the computational system actively shapes the narrative without direct reader input and consequently propose a reconceptualization of the concept of interpassivity and its relationship with interactivity.
2025
Authors
Bost, L; Fernandes, FS; Bessa, RJ;
Publication
SUSTAINABLE ENERGY GRIDS & NETWORKS
Abstract
The increasing penetration of renewable energy sources in power systems has heightened the importance of grid-forming (GFM) converters, which emulate the dynamic behavior of synchronous machines and are crucial for ensuring stability in converter-dominated grids. However, the complexity of modern grids calls for innovative control mechanisms to unlock the full potential of GFM technology. This work presents a novel automated framework for control design in power systems. Simulated annealing is used to evolve the structural design of control systems represented as graph-based models. The method achieves greater flexibility by using control graphs instead of traditional tree-based representations, supporting complex feedback loop configurations. A simplification process is also included to reduce complexity and improve interpretability, ensuring practical applicability. Validation on a two-generator power system with one GFM converter demonstrates the method's ability to design robust controllers that enhance system stability, achieving better performance metrics, such as smoother frequency responses with significantly reduced frequency deviations compared to benchmark configurations. The improved frequency response arises from differing terminal angle profiles, enabling faster, stronger power responses that quickly arrest frequency deviations during disturbances.
2025
Authors
Caldeira, E; Cardoso, JS; Sequeira, AF; Neto, PC;
Publication
COMPUTER VISION-ECCV 2024 WORKSHOPS, PT XV
Abstract
As in school, one teacher to cover all subjects is insufficient to distill equally robust information to a student. Hence, each subject is taught by a highly specialised teacher. Following a similar philosophy, we propose a multiple specialized teacher framework to distill knowledge to a student network. In our approach, directed at face recognition use cases, we train four teachers on one specific ethnicity, leading to four highly specialized and biased teachers. Our strategy learns a project of these four teachers into a common space and distill that information to a student network. Our results highlighted increased performance and reduced bias for all our experiments. In addition, we further show that having biased/specialized teachers is crucial by showing that our approach achieves better results than when knowledge is distilled from four teachers trained on balanced datasets. Our approach represents a step forward to the understanding of the importance of ethnicity-specific features.
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