ESTCB - Artigos em revistas com arbitragem científica
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- Determination of dynamic elastic properties of 3D-printed nylon 12CF using impulse excitation of vibrationPublication . Garcia, Pedro F.; Ramalho, Armando; Vasco, Joel; Rubén, Rui; Capela, Carlos; MDPIMaterial Extrusion (MEX) process is increasingly used to fabricate components for structural applications, driven by the availability of advanced materials and greater industrial adoption. In these contexts, understanding the mechanical performance of printed parts is crucial. However, conventional methods for assessing anisotropic elastic behavior often rely on expensive equipment and time-consuming procedures. The aim of this study is to evaluate the applicability of the impulse excitation of vibration (IEV) in characterizing the dynamic mechanical properties of a 3D-printed composite material. Tensile tests were also performed to compare quasi-static properties with the dynamic ones obtained through IEV. The tested material, Nylon 12CF, contains 35% short carbon fibers by weight and is commercially available from Stratasys. It is used in the fused deposition modeling (FDM) process, a Material Extrusion technology, and exhibits anisotropic mechanical properties. This is further reinforced by the filament deposition process, which affects the mechanical response of printed parts. Young’s modulus obtained in the direction perpendicular to the deposition plane (E33), obtained via IEV, was 14.77% higher than the value in the technical datasheet. Comparing methods, the Young’s modulus obtained in the deposition plane, in an inclined direction of 45 degrees in relation to the deposition direction (E45), showed a 22.95% difference between IEV and tensile tests, while Poisson’s ratio in the deposition plane (v12) differed by 6.78%. This data is critical for designing parts subject to demanding service conditions, and the results obtained (orthotropic elastic properties) can be used in finite element simulation software. Ultimately, this work reinforces the potential of the IEV method as an accessible and consistent alternative for characterizing the anisotropic properties of components produced through additive manufacturing (AM).
- Dynamic elastic properties of E-Glass randomly oriented fiber reinforced SR GreenPoxy composite - Experimental and numerical analysisPublication . Ramalho, Armando; Gaspar, Marcelo; Correia, Mário; Vasco, Joel; Capela, Carlos; Rubén, RuiIn this article, the in-plane dynamic elastic properties of an E-glass randomly oriented fiber-reinforced SR GreenPoxy 56 composite were obtained based on the procedure specified in the ASTM E1876-21 standard. The experimental frequencies and the ones predicted by the simulation of the experimental procedure using a finite element analysis developed in the Patran/Nastran 2021 package were used in an iterative algorithm using sensitivity analysis to improve the first approaches of the dynamic elastic properties obtained by the impulse excitation technique. These experimental results are compared with the ones obtained by the 2D Short Fiber Composite model of the E-glass randomly oriented fiber-reinforced SR GreenPoxy 56 composite, developed in the Patran/Nastran 2021 software.
- Empirical evidence of AI-enabled accessibility in digital gastronomy: Development and evaluation of the Receitas +Power PlatformPublication . Serra, Paulo; Oliveira, Ângela; Fidalgo, Filipe; Serra, Bruno; Infante, Tiago; Baião, LuísThis study explores how artificial intelligence can promote accessibility and inclusiveness in digital culinary environments. Centred on the Receitas +Power platform, the research adopts an exploratory, multidimensional case study design integrating qualitative and quantitative analyses. The investigation addresses three research questions concerning (i) user empowerment beyond recommendation systems, (ii) accessibility best practices across disability types, and (iii) the effectiveness of AI-enabled inclusive solutions. The system was developed following user-centred design principles and WCAG 2.2 standards, combining generative AI modules for recipe creation with accessibility features such as voice interaction and adaptive navigation. The evaluation, conducted with 87 participants, employed the System Usability Scale complemented by thematic qualitative feedback. Results indicate excellent usability (M = 80.6), high reliability (Cronbach’s α = 0.798–0.849), and moderate positive correlations between usability and accessibility dimensions (r = 0.45–0.55). Participants highlighted the platform’s personalisation, clarity, and inclusivity, confirming that accessibility enhances rather than restricts user experience. The findings provide empirical evidence that AI-driven adaptability, when grounded in universal design principles, offers an effective and ethically sound pathway toward digital inclusion. Receitas +Power thus advances the field of inclusive digital gastronomy and presents a replicable framework for human–AI co-creation in accessible web technologies.
- Evacuation of Lisbon’s Baixa-Chiado subway station in case of firePublication . Borralho, Tiago; Rodrigues, João Paulo; Calmeiro dos Santos, CristinaIt is essential to ensure that any building has conditions for a safe evacuation of its occupants. This aspect is essential in subway stations, where evacuation has to be carried out in an upward way, and usually correspond to large structures constituting a single fire compartment. Baixa-Chiado subway station, in Lisbon, Portugal, was selected for studying the evacuation in case of fire, due to its depth, high number of passengers that frequent the station and the existing of two intersecting train lines. A calculation of evacuation time was calculated and the way of evacuation studied, in different fire scenarios, number and location of occupants. The numerical simulations used Fire Dynamics Simulator and Pathfinder softwares, the first for fire spreading and the second for evacuation analysis. The importance of smoke control system, and its rapid activation in case of fire, was highlighted by the results obtained. In situations where this did not occur, there was a significant worsening in the evacuation of the occupants. It was estimated the incapacitation of a significant number of occupants, considering the levels registered for the fractional effective dose. The station’s architectural constraints proved to be a crucial factor in the results of the study. This article highlights important results applicable to subway stations around the world.
- Fatigue analysis of sustainable bituminous pavements with artificial and recycled aggregatesPublication . Teijón-López-Zuazo, Evelio; Vega-Zamanillo, Ángel; Santos, C.C.; Gómez-Carrascal, DavidThe circular economy represents a significant opportunity to enhance the mechanical properties of bituminous mixtures, thereby contributing to sustainable development. This research compares the behaviour of traditional bituminous mixtures with sustainable ones that reuse recycled materials, industrial waste products, or additives that improve mechanical or rheological properties. The methodology employed comprised the acquisition of fatigue resistance laws from 4-point bending tests on prismatic specimens. This facilitated the analytical determination of the number of axles of 13 tons that the section of pavement with sustainable material can support for comparison with the axles supported in the conventional mix. The findings corroborate the utilization of sustainable bituminous mixtures in pavement sections, employing the maximum circularity criterion. The fatigue laws calculated must permit the use of different calculation methods or other applications in green infrastructures, such as cycling lanes or pedestrian areas. On sections with an AADT of between 800 and 25 HV/day, all of the analyzed bituminous mixtures with sustainable materials prolong the service life of the road. There were increases in service life of between 25.5% and 6.6%, respectively, which satisfactorily achieved an increase in pavement service life based on the criterion of maximum circularity.
- Fire safety regulations in Brazil: Analysis of the occupancy classification of buildingsPublication . Minervino, Bernardete de Lourdes Ferreira; Santos, C.C.; von Krüger, Paulo Gustavo; Rodrigues, João Paulo CorreiaFire safety in a building depends on several factors, including its use and occupancy, which fire protection systems are present in the building and the state of maintenance of these systems. Considering the fact that Brazil has 27 federal states and each of them has its own fire safety legislation, it is common for there to be divergences that result in different protection requirements depending on the state where the building is located. This study analyzes Brazilian state fire safety legislation with regard to the sizing of fire protection systems for buildings, considering the parameters used for such sizing. It then identifies the differences in classification in terms of the use and occupation of buildings in the 27 federal states; and presents a proposal for a standardized classification for the whole country, taking into account the convergences that already exist in state legislation. The main objective is to suggest a discussion starter for the process of standardizing fire safety parameters in Brazil.
- Gamification and emotional intelligence: Development of a digital application for childrenPublication . Nunes, Maria; Oliveira, Ângela; Fidalgo, FilipeIt is important to work on educating children’s emotional intelligence, namely the re-awareness and control of emotions, both their own and those around them so that they feel empathy for others, establish and maintain positive relationships and make conscious decisions. This document describes a proposal for a gamified solution, based on the development of a multimedia product, which aims to help children, parents and teachers in the education of emotional intelligence in children. The solution makes it possible to present everyday scenarios to children, allowing adults to find out how they feel and, based on this information, to work on feelings and social behaviour. The solution was based on research into studies available in scientific databases on children’s emotional intelligence, as well as research into exercises that can help work on this same issue. Once implemented, the solution was tested with children from a primary school, where it was possible to collect feedback from them and their teachers and make improvements. This study presentsthe design, development and evaluation of a gamified application for children focused on emotional intelligence. The methodology used is based on a systematic literature review following the PRISMA protocol and the development of an iterative multimediaproduct. The study sample included around 200 elementary school children, where it was possible to collect qualitative feedback to evaluate the effectiveness of the application. The results obtained made it possible to make improvements to the design of the application and to obtain feedback from the teachers, which was very positive, but transmitted by direct interview.
- High frequency ultrasonic condition monitoring framework based on edge-computing and telemetry stack approachPublication . Spencer, Geoffrey; Torres, Pedro; Pinto, Vítor H.; Gonçalves, GilThis paper presents initial developments towards a high-frequency condition monitoring framework designed for Autonomous Mobile Robots (AMRs) in Smart Factory environments. The proposed approach focuses on data acquisition and edge-level processing at the ultrasound range specifically (>20 kHz), using Micro-Electro-Mechanical System (MEMS) sensors. The system integrates real-time data acquisition, embedded fixed-point frequency-domain processing via a 1024-point FFT, and the integration of Industrial Internet-of-Things (IIoT) infrastructure based on the TIG (Telegraf, InfluxDB, and Grafana) stack, for data aggregation and remote visualization. To ensure timing precision at a sampling rate of 160 kHz, a software-based calibration routine is implemented to compensate for microcontroller overhead. Furthermore, the architecture’s alignment with IEEE 1451 principles is discussed to support interoperable and scalable sensor integration. Experimental results validate the reliable acquisition and processing of ultrasonic signals up to 80 kHz using controlled acoustic sources. This work provides a foundational infrastructure for condition-based monitoring, enabling future development of automated anomaly detection for mechanical components, such as bearings, which exhibit early-stage fault signatures in the ultrasonic spectrum.
- A hybrid modelling for both pressure-dependent and volume-based demand in pressure-driven analysisPublication . Muranho, João; Sousa, Joaquim; Ferreira, Ana Maria; Marques, Alfeu Sá; Gomes, AbelWater distribution network (WDN) simulation models are usually classified as demanddriven or pressure-driven, depending on whether the demands are independent of or dependent on network pressures, respectively. In real-world networks, both types of demands coexist in the same building. This paper presents a hybrid modelling approach that combines volume-based and pressuredependent demands in the same model, allowing for different pressure–demand relationships. This hybrid modelling approach is intended to produce more realistic results when modelling WDNs, and it was implemented in WaterNetGen, an EPANET extension.
- Inclusive digital gaming platformPublication . Mendonça, Rodrigo; Lopes, Salvador; Oliveira, Ângela; Serra, Paulo; Fidalgo, FilipeThe lack of accessibility in digital gaming platforms remains a significant barrier to equitable user participation. To address this issue, this article presents an inclusive solution developed as a multimedia project designed to promote access to digital games for any user through the ipcb.games platform. The platform offers features that enhance accessibility, including voice-based authentication, voice-assisted registration, facial recognition, visual and auditory feedback, and a simplified interface. It also enables users to submit their own games for subsequent approval and integration. The development process followed a multimedia project methodology, structured into phases of analysis, planning, design, production, testing, and validation. The proposal was informed by a systematic review of scientific literature on digital inclusion and accessibility, complemented by a comparative analysis of existing platforms. During usability testing, the platform was evaluated by approximately 50 teachers from different educational levels, who provided highly positive feedback. Future work includes implementing voice-controlled gameplay, enabling keyboard-based navigation, re-implementing a functional eye-tracking system, and creating pedagogical groups, further strengthening the platform’s role in educational contexts.