2025
Autores
Bécue, A; Gama, J; Brito, PQ;
Publicação
Strategic Business Research
Abstract
2025
Autores
Wu, X; Spiliopoulou, M; Wang, C; Kumar, V; Cao, L; Zhou, X; Pang, G; Gama, J;
Publicação
PAKDD (7)
Abstract
2025
Autores
Ferreira, L; Maciel, MVM; de Carvalho, JV; Silva, E; Alvelos, FP;
Publicação
EUROPEAN JOURNAL OF OPERATIONAL RESEARCH
Abstract
The Prisoner Transportation Problem is an NP-hard combinatorial problem and a complex variant of the Dial-a- Ride Problem. Given a set of requests for pick-up and delivery and a homogeneous fleet, it consists of assigning requests to vehicles to serve all requests, respecting the problem constraints such as route duration, capacity, ride time, time windows, multi-compartment assignment of conflicting prisoners and simultaneous services in order to optimize a given objective function. In this paper, we present anew solution framework to address this problem that leads to an efficient heuristic. A comparison with computational results from previous papers shows that the heuristic is very competitive for some classes of benchmark instances from the literature and clearly superior in the remaining cases. Finally, suggestions for future studies are presented.
2025
Autores
Abreu, A; Oliveira, DD; Vinagre, I; Cavouras, D; Alves, JA; Pereira, AI; Lima, J; Moreira, FTC;
Publicação
CHEMOSENSORS
Abstract
The detection of glucose is crucial for diagnosing diseases such as diabetes and enables timely medical intervention. In this study, a disposable enzymatic screen-printed electrode electrochemical biosensor enhanced with machine learning (ML) for quantifying glucose in serum is presented. The platinum working surface was modified by chemical adsorption with biographene (BGr) and glucose oxidase, and the enzyme was encapsulated in polydopamine (PDP) by electropolymerisation. Electrochemical characterisation and morphological analysis (scanning and transmission electron microscopy) confirmed the modifications. Calibration curves in Cormay serum (CS) and selectivity tests with chronoamperometry were used to evaluate the biosensor's performance. Non-linear ML regression algorithms for modelling glucose concentration and calibration parameters were tested to find the best-fit model for accurate predictions. The biosensor with BGr and enzyme encapsulation showed excellent performance with a linear range of 0.75-40 mM, a correlation of 0.988, and a detection limit of 0.078 mM. Of the algorithms tested, the decision tree accurately predicted calibration parameters and achieved a coefficient of determination above 0.9 for most metrics. Multilayer perceptron models effectively predicted glucose concentration with a coefficient of determination of 0.828, demonstrating the synergy of biosensor technology and ML for reliable glucose detection.
2025
Autores
Silva, VF; Silva, ME; Ribeiro, P; Silva, F;
Publicação
DATA MINING AND KNOWLEDGE DISCOVERY
Abstract
Multivariate time series analysis is a vital but challenging task, with multidisciplinary applicability, tackling the characterization of multiple interconnected variables over time and their dependencies. Traditional methodologies often adapt univariate approaches or rely on assumptions specific to certain domains or problems, presenting limitations. A recent promising alternative is to map multivariate time series into high-level network structures such as multiplex networks, with past work relying on connecting successive time series components with interconnections between contemporary timestamps. In this work, we first define a novel cross-horizontal visibility mapping between lagged timestamps of different time series and then introduce the concept of multilayer horizontal visibility graphs. This allows describing cross-dimension dependencies via inter-layer edges, leveraging the entire structure of multilayer networks. To this end, a novel parameter-free topological measure is proposed and common measures are extended for the multilayer setting. Our approach is general and applicable to any kind of multivariate time series data. We provide an extensive experimental evaluation with both synthetic and real-world datasets. We first explore the proposed methodology and the data properties highlighted by each measure, showing that inter-layer edges based on cross-horizontal visibility preserve more information than previous mappings, while also complementing the information captured by commonly used intra-layer edges. We then illustrate the applicability and validity of our approach in multivariate time series mining tasks, showcasing its potential for enhanced data analysis and insights.
2025
Autores
Castro, JP; Campos, JC;
Publicação
2025 INTERNATIONAL CONFERENCE ON GRAPHICS AND INTERACTION, ICGI
Abstract
User-centred design is an iterative process that involves ideation, testing, and refinement to enhance usability, functionality, and overall user experience. However, there is still a need to code the final design. This transition from design to implementation is a time-consuming task. In this paper, we propose an approach and its supporting tool to generate a web application's front-end code from a prototype of its user interface. Our goal is to generate code that can be easily integrated into the overall application development. The results demonstrate that the proposed tool can achieve visual fidelity comparable to that of existing commercial plugins, while producing higher-quality code that better reflects the behaviour specified in the prototype.
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