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Publicações

2025

Local flexibility markets based on grid segmentation

Autores
Retorta F.; Mello J.; Gouveia C.; Silva B.; Villar J.; Troncia M.; Chaves-Ávila J.P.;

Publicação
Utilities Policy

Abstract
Local flexibility markets are a promising solution to aid system operators in managing the network as it faces the growth of distributed resources and the resulting impacts on voltage control, among other factors. This paper presents and simulates a proposal for an intra-day local flexibility market based on grid segmentation. The design provides a market-based solution for distribution system operators (DSOs) to address near-real-time grid issues. The grid segmentation computes the virtual buses that represent each zone and the sensitivity indices that approximate the impact of activating active power flexibility in the buses within the zone. This approach allows DSOs to manage and publish their flexibility needs per zone and enables aggregators to offer flexibility by optimizing their resource portfolios per zone. The simulation outcomes allow for the assessment of market performance according to the number of zones computed and show that addressing overloading and voltage control through zonal approaches can be cost-effective and counterbalance minor errors compared to node-based approaches.

2025

A 3-level integrated lot sizing and cutting stock problem applied to a truck suspension factory

Autores
Andrade, PRD; De Araujo, SA; Cherri, AC; Lemos, FK;

Publicação
TOP

Abstract
This paper studies the process of cutting steel bars in a truck suspension factory with the objective of reducing its inventory costs and material losses. A mathematical model is presented that focuses on decisions for a medium-term horizon (4 periods of 2 months). This approach addresses the one-dimensional 3-level integrated lot sizing and cutting stock problem, considering demand, inventory costs and stock level limits for bars (objects-level 1), springs (items-level 2) and spring bundles (final products-level 3), as well as the acquisition of bars as a decision variable. The solution to the proposed mathematical model is reached through an optimization package, using column generation along with a method for achieving integer solutions. The results obtained with real data demonstrate that the method provides significantly better solutions than those carried out at the company, whilst using reduced computational time. Additionally, the application of tests with random data enabled the analysis of both the effect of varying parameters in the solution, which provides managerial insights, and the overall performance of the method.

2025

Generative adversarial networks with fully connected layers to denoise PPG signals

Autores
Castro, IAA; Oliveira, HP; Correia, R; Hayes-Gill, B; Morgan, SP; Korposh, S; Gomez, D; Pereira, T;

Publicação
PHYSIOLOGICAL MEASUREMENT

Abstract
Objective.The detection of arterial pulsating signals at the skin periphery with Photoplethysmography (PPG) are easily distorted by motion artifacts. This work explores the alternatives to the aid of PPG reconstruction with movement sensors (accelerometer and/or gyroscope) which to date have demonstrated the best pulsating signal reconstruction. Approach. A generative adversarial network with fully connected layers is proposed for the reconstruction of distorted PPG signals. Artificial corruption was performed to the clean selected signals from the BIDMC Heart Rate dataset, processed from the larger MIMIC II waveform database to create the training, validation and testing sets. Main results. The heart rate (HR) of this dataset was further extracted to evaluate the performance of the model obtaining a mean absolute error of 1.31 bpm comparing the HR of the target and reconstructed PPG signals with HR between 70 and 115 bpm. Significance. The model architecture is effective at reconstructing noisy PPG signals regardless the length and amplitude of the corruption introduced. The performance over a range of HR (70-115 bpm), indicates a promising approach for real-time PPG signal reconstruction without the aid of acceleration or angular velocity inputs.

2025

Delivering energy from hybridised offshore wind-wave parks considering electricity and hydrogen options: an optimisation approach

Autores
Varotto, S; Kazemi-Robati, E; Silva, B;

Publicação
SUSTAINABLE ENERGY GRIDS & NETWORKS

Abstract
Research around the co-location of different renewable energy technologies in offshore sites is increasing due to the potential complementarity of different sources that could decrease the power output variability, and increase reliability. However, further decrease of the power fluctuations and higher economic profitability could be achieved with energy storage. In this work, a model is developed for optimal sizing and energy management of energy storage and delivery solutions to accommodate the hybridisation of an offshore wind park. A set of options is considered for energy storage: the integration of a battery energy storage system (BESS), hydrogen production for direct sale or hydrogen/fuel cell system. For energy delivery, an expansion of the transmission cable, hydrogen pipeline or transportation by ship is evaluated. The case study used to test the model is the offshore farm WindFloat Atlantic located near the coast of Viana do Castelo, Portugal, which is proposed to be hybridised with wave energy converters (WEC). Sensitivity analyses are performed on possible components' cost variations, hydrogen shipping frequency or sale price. The results show that hydrogen production from the studied offshore hybrid park is profitable, and the transmission through submarine pipeline is competitive with electrical connections by cable. The highest profitability is achieved when pipeline and cable expansion are combined. Hydrogen transportation by ship also appears profitable, in the eventuality that additional submarine transmission facilities cannot be installed.

2025

Dynamic Data Radio Bearer Management for O-RAN Slicing in 5G Standalone Networks

Autores
Silva, P; Dinis, R; Coelho, A; Ricardo, M;

Publicação
Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering, LNICST

Abstract
The rapid growth of data traffic and evolving service demands are driving a shift from traditional network architectures to advanced solutions. While 5G networks provide reduced latency and higher availability, they still face limitations due to reliance on integrated hardware, leading to configuration and interoperability challenges. The emerging Open Radio Access Network (O-RAN) paradigm addresses these issues by enabling remote configuration and management of virtualized components through open interfaces, promoting cost-effective, multi-vendor interoperability. Network slicing, a key 5G enabler, allows for tailored network configurations to meet heterogeneous performance requirements. The main contribution of this paper is a private Standalone 5G network based on O-RAN, featuring a dynamic Data Radio Bearer Management xApp (xDRBM) for real-time metric collection and traffic prioritization. xDRBM optimizes resource usage and ensures performance guarantees for specific applications. Validation was conducted in an emulated environment representative of real-world scenarios. © ICST Institute for Computer Sciences, Social Informatics and Telecommunications Engineering 2025.

2025

Emerging technologies for supporting patients during Hemodialysis: A scoping review

Autores
Martins, AR; Ferreira, MC; Fernandes, CS;

Publicação
INTERNATIONAL JOURNAL OF MEDICAL INFORMATICS

Abstract
Purpose:To synthesizethe availableevidenceaboutthe use of HealthInformationTechnology(HIT)to supportpatientsduringhemodialysis.Methods:TheJoannaBriggsInstitute's methodologicalguidelinesfor scopingreviewsandthe PRISMA-ScRchecklistwereemployed.BibliographicsearchesacrossMEDLINE (R), CINAHL (R), PsychologyandBehavioralSciencesCollection,Scopus,MedicLatina,and Cochraneyielded932 records.Results:Eighteenstudiespublishedbetween2003and2023wereincluded.Theyexploreda rangeof HITs,includingvirtualreality,exergames,websites,and mobileapplications,all specificallydevelopedfor use duringthe intradialyticperiod.Conclusion:Thisstudyhighlightsthe HITsdevelopedfor use duringhemodialysistreatment,supportingphysicalexercise,diseasemanagement,and enhancementof self-efficacyand self-care.

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