RCIPL
Repositório Institucional do Politécnico de Lisboa
Entradas recentes
Embedding computational thinking in engineering and energy fundamentals: A PBL–experiential design supporting conceptual engagement and skill development
Publication . Soares Domingues, Nuno Alexandre; Costa, Maria Cristina; Domingues, António
Introductory electrical engineering courses frequently emphasise procedural calculation rather than conceptual reasoning and systems‐level problem solving. Although computational thinking (CT) has been recognised as relevant for engineering education, its explicit integration within undergraduate engineering practice remains insufficiently explored. This study investigates how CT can be embedded and analysed within an ICT‐supported problem‐based learning (PBL) environment aligned with Kolb's experiential learning cycle in undergraduate electrical engineering education. A design‐based research approach was implemented during a 14‐week intervention in electrotechnics and electrical machines courses. Custom‐developed simulation tools were integrated into lecture and laboratory activities to support collaborative problem solving, parameter exploration and student‐generated engineering problems. Data sources included student‐generated artefacts, reflection reports, simulationbased activities and structured classroom observations. Analysis employed predefined coding rubrics aligned with five CT dimensions: abstraction, decomposition, algorithmic thinking, automation and generalisation. Inter‐rater agreement exceeded Cohen's κ > 0.80. Student‐generated artefacts increasingly demonstrated explicit circuit decomposition, structured analytical procedures and transfer of reasoning strategies across DC and AC contexts. Simulation tools evolved from being used primarily for answer verification to supporting exploratory modelling and comparative analysis of alternative circuit conditions. Classroom observations indicated increased collaborative reasoning, engagement and autonomous problem formulation during later intervention phases. Descriptive coding frequencies across artefacts and observations provided convergent evidence of increased enactment of CT‐related behaviours over time. The study demonstrates how CT can be operationalised within foundational electrical engineering education through the integration of ICT‐supported simulation environments, PBL activities and experiential learning structures. The work contributes a replicable instructional and analytical framework linking CT dimensions with observable engineering problem‐solving practices and technology‐supported learning activities.
A reconfigurable electro-optic photonic integrated circuit architecture
Publication . Moreira, André; Velázquez, Ernesto; Lourenço, Paulo; Fantoni, Alessandro
In this work, we present the design and numerical validation of a reconfigurable electro-optic photonic integrated circuit architecture for dynamic 1 & times; 4 optical routing, based on electro-optic phase shifters and a chain of cascaded multimode interference structures, and implemented in an amorphous silicon platform. By exploiting recent developments in symmetry-engineered silicon photonics to enable phase control in a platform compatible with complementary metal-oxide-semiconductor fabrication requirements, this approach addresses the increasing demand for ultra-fast, compact and energy efficient reconfigurable photonic integrated circuits. The photonic circuit design bases its functionality on self-imaging theory and has been optimized through simulations implementing the beam propagation method, while optical performance and electro-optical behavior have been validated through finite difference time-domain simulations and multiphysics modeling. The numerical results obtained confirm the operational performance of the individual building blocks and demonstrate the proposed architecture as being able to perform as a reconfigurable electro-optic platform and provide the dynamic 1 & times; 4 optical routing. Hence, this architecture provides a scalable platform for reconfigurable silicon photonics, complementary metal-oxide-semiconductor compatible, and the fabrication-ready layout establishes a practical path to experimental validation and future reconfigurable photonic integrated circuits.
A new, simple, and effective variationally consistent mixed finite element formulation for the geometrically exact planar analysis of beams and frames
Publication . Freixial Argente dos Santos, Hugo Alexandre
A robust and efficient mixed finite element formulation, applicable to both shear-rigid (Kirchhoff-type) and shear-flexible (Reissner-type) beam theories, is proposed for the geometrically exact planar analysis of beams and frames. The formulation is derived from a Hellinger-Reissner-type variational principle, in which the spatial components of the internal forces, bending moment, and cross-sectional rotation are adopted as primary unknowns. Equilibrium of the spatial internal forces is satisfied in strong form at the member level, while the assumed bending moment field is C0 -continuous and satisfies equilibrium boundary conditions. The formulation is intrinsically free from shear- and membrane-locking phenomena, admits explicit closed-form expressions for both the residual vector and the consistent symmetric tangent matrix, and yields a highly sparse and banded global system with a reduced number of unknowns compared with conventional displacement-based formulations and previously proposed hybrid-mixed formulations. Displacement fields are recovered a posteriori by integrating the kinematic compatibility relations, producing globally C0 -continuous fields that satisfy all prescribed kinematic boundary conditions. Nonlinear equilibrium paths are traced using an arc-length strategy with a linear extrapolation predictor, and critical points are identified through the determinant of a Schur-complement-based equivalent stiffness matrix that emerges naturally from the formulation. Numerical examples demonstrate the accuracy, convergence, and robustness of the proposed approach, including verification against analytical solutions under pure bending, assessment of shear-locking performance, and the simulation of complex nonlinear responses involving snap-through, snap-back, and symmetry-breaking bifurcation phenomena.
Optimized wavelet-denoised temporal convolutional network for multi-step ahead predictions in power systems
Publication . Buratto, William Gouvea; Gonzalez, Gabriel Villarrubia; Yamaguchi, Cristina Keiko; Nied, Ademir; Yow, Kin-Choong; Stefenon, Stefano Frizzo
Accurate forecasting of power generation is essential for ensuring the reliable and cost-efficient operation of modern electrical grids. This paper introduces an optimized wavelet temporal convolutional network (TCN) designed for multi-step-ahead prediction of thermal power generation in Brazil. The proposed model, called optimized-wavelet-TCN, integrates a discrete wavelet transform denoising stage to effectively filter high-frequency noise from operational data while preserving underlying signal trends, followed by a TCN optimized via a tree-structured Parzen estimator for hyperparameter tuning. Evaluated on real-world hourly data spanning multiple years, the optimized-wavelet-TCN achieves superior forecasting performance with a mean absolute percentage error of 10.2%, 7.24%, and 8.54% for 15, 30, and 60-step ahead predictions, respectively. The model significantly reduces computational time to only 1.54 s for a 30-step forecast, markedly outperforming state-of-the-art transformer-based and recurrent neural network baselines in both accuracy and efficiency.
Casimir-mediated amplification of flexural modes in suspended graphene
Publication . Ribeiro, Sofia; Terças, Hugo
We develop a minimal theoretical framework to describe near-field Casimir-mediated coupling between two suspended nanomembranes: a graphene sheet and a gold-coated GaAs membrane separated by a micrometer-scale vacuum gap. Coherent excitation of flexural (out-of-plane) modes in the gold membrane, provided by an external piezoelectric drive, enables efficient energy transfer to graphene through static vacuum electromagnetic coupling. Using a coupled-mode description equivalent to the classical equations of motion, we identify hybridized flexural modes exhibiting avoided crossings, tunable spectral response, and drive-dependent energy exchange. Under experimentally accessible conditions, Casimir-mediated mode hybridisation transfers energy from the driven gold membrane to graphene at rates comparable to or exceeding the intrinsic mechanical losses of graphene, resulting in a strong enhancement of its flexural response and linewidth narrowing. The Casimir interaction acts here solely as a static, non-contact coupling mechanism, while all energy is supplied externally through coherent mechanical driving, yielding drive-induced amplification without intrinsic negative damping. Our results establish Casimir coupling as a practical resource for controlling flexural dynamics in graphene nanomembranes and provide a platform for non-contact energy transfer and mode-selective amplification in two-dimensional mechanical systems.