ESTiG - Artigos em Revistas Indexados à WoS/Scopus
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Percorrer ESTiG - Artigos em Revistas Indexados à WoS/Scopus por Objetivos de Desenvolvimento Sustentável (ODS) "11:Cidades e Comunidades Sustentáveis"
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- An AI-driven Ukrainian history web platformPublication . Kolomiets, Valentyna; Oliveira, Pedro Filipe; Matos, PauloThe AI-driven Ukrainian History web platform offers an innovative way for users to engage with the nation’s rich history. By integrating artificial intelligence, natural language processing (NLP), and geospatial analysis, it presents historical events, significant locations, and notable figures in an interactive and visually engaging format. The platform systematically gathers historical data using tools like Scrapy for web scraping and Tesseract OCR for digitizing scanned documents. While noisy or degraded documents may affect accuracy, the availability of high-quality sources ensures reliable data extraction. Fine-tuned NLP models, including transformers like BERT and RoBERTa, process the data to identify and categorize key entities such as dates, locations, and names of historical figures. Contextual summarization ensures the extracted information is both accurate and easy to understand. Geospatial data is managed with PostGIS, an extension of PostgreSQL, and visualized using Leaflet.js. An interactive map interface enables users to explore events by location and time period, with filters for categories like political milestones or cultural events. The backend, built on PostgreSQL, ensures scalability and performance, while development in Visual Studio Code streamlined integration across components. This platform not only preserves Ukraine’s cultural heritage but also demonstrates the potential of modern technology to transform historical education, offering an intuitive way to connect with the past and explore its influence on Ukraine’s landscape and culture.
- Analyses of pandemics’ quantitative data and economic indicatorsPublication . Carvalho, Kathleen; Reis, Luis Paulo; Teixeira, João PauloThe proposed work is a study that attempts to evaluate the financial impacts of pandemic mitigation strategies in order to be part of a central model that forecasts different scenarios in pandemic situations considering the impact of mitigation procedures in the Economic System and Healthcare System. Economic fluctuations impose a more significant challenge on prediction models, and pandemic modeling methodologies are primarily concerned with the variability of epidemic features, the efficiency of control measures over time, and the development of different viral variants. In this context, this paper correlates economic indicators with quantitative parameters of the last three respiratory virus pandemics, specifically the GDP and the unemployment rates, with a sample encompassing three European countries, the United Kingdom (UK), France, and Germany, that pass through the pandemics under study. The results provide intriguing information, such as the moderated and weak correlation factor between deaths with GDP in the Spanish flu and Swine flu, and the WWI and the 2009 crises can explain which. On the other hand, the correlation factors associated with COVID-19 show a weak to moderate correlation parameter with GDP and unemployment rates but present interesting numbers when the number of people fully vaccinated is compared with GDP. Also, as the correlation factor does not presente a strong relation between daily deaths and GDP, this indicates a necessity for comparison with other economic parameters.
- Assessing the impact of working capital on free cash flow: evidence from portuguese accommodation companiesPublication . Fernandes, António B. ; Cardim, Sofia; Ferreira, Jessica; Pinto, LígiaThis study analyses the impact of working capital (WC) on free cash flow (FCF) for Portuguese firms operating in Division 55 (Accommodation), a sector that is a central pillar of the national tourism industry and characterised by high capital intensity and pronounced seasonality. The empirical analysis is based on an unbalanced panel dataset of 5,744 firms, corresponding to 27,689 firm-year observations for the period 2011–2023, obtained from the SABI database. A panel data model is estimated using generalised estimating equations (GEE) with firm- and year-fixed effects to examine how changes in WC and its components influence firms’ capacity to generate FCF. Twelve research hypotheses are formulated and empirically tested within a cash-flow-based valuation framework. The results show that variations in WC have a negative and statistically significant effect on FCF, indicating that increased investment in short-term operational assets constrains liquidity generation in the accommodation sector. Several components of WC are identified as significant determinants of FCF, while others do not exhibit statistically significant effects, underscoring the heterogeneous influence of short-term assets and liabilities on cash flow dynamics. The model adjustment criteria (QIC and QICC), assessed within the scope of the GEE, indicate that the estimated specification is well suited and robust, supporting the reliability of the results obtained. Although the analysis is limited to the accommodation sector, which may restrict the generalisability of the findings, the study makes an important contribution by adopting an FCF-based perspective on WC management. By focusing on liquidity generation rather than traditional profitability measures, this research enhances understanding of financial management dynamics in tourism-related firms and provides insights into firms’ strategic flexibility and capacity to invest in market-facing activities.
- Comparação de métodos de dimensionamento geotécnico e estrutural de microestacas: análise por meio de estudo paramétricoPublication . Souza, Lucas de Freitas; Braz-César, Manuel; Pereira, Armando Belato; Paula, António MiguelEste artigo apresenta uma análise crítica de diferentes métodos de dimensionamento geotécnico e estrutural aplicáveis a microestacas. Foram avaliados métodos clássicos e contemporâneos, considerando-se variáveis geométricas como o diâmetro de perfuração, comprimento da raiz e propriedades da armadura tubular. A metodologia incluiu um estudo de caso real, baseado em dados de campo e parâmetros obtidos por sondagem dinâmica, complementado por análises paramétricas implementadas em ambiente computacional. Os resultados permitiram quantificar a sensibilidade de cada método às alterações geométricas, destacando as divergências entre critérios de capacidade de carga do solo e de estabilidade estrutural. Verificou-se que alguns métodos apresentam variações significativas nos resultados. A abordagem adotada proporciona uma base técnica mais sólida para a comparação entre diferentes modelos de dimensionamento de fundações profundas, contribuindo para escolhas mais fundamentadas em projetos de fundações em ambientes urbanos ou industriais.
- Experimental investigation of cellular steel beams at ambient and elevated temperaturesPublication . Silva, Luana Vidoti da; Giacomitti, Nickolas; Ferreira, Débora; Lopes, Nuno; Mesquita, Luís M.R.Cellular steel beams, commonly used in modern construction, exhibit complex failure mechanisms that have not been thoroughly explored, especially under fire conditions. This research investigates the structural behaviour of cellular beams under both ambient and elevated temperatures, with a focus on load-bearing capacity and failure modes. Experimental tests were conducted on a solid beam and six cellular beams with varying hole spacings and diameters at different temperatures. All beams were tested under three-point bending, subjecting the openings and the web posts to different combinations of bending moments and shear forces. Experimental maximum loads and failure modes are compared with the design method of EN1993-1-13 and EN1993-1-2. At ambient temperature, failure modes varied with beam design: specimens with smaller opening spacings failed by web-post buckling, while larger openings resulted in a Vierendeel mechanism. While the Eurocode predictions for load capacity were conservative under ambient conditions, the design model did not accurately predict the correct failure mode. Elevated temperatures significantly reduced the load capacity and, in some cases, changed the collapse mechanism. These results highlight that current design rules are unreliable in predicting the failure mode and may not ensure safety at higher temperatures, stressing the need for specific design rules for cellular beams in fire conditions.
- Fire resistance of protected glued laminated timber columns: geometry, load and cladding effectPublication . Piloto, Paulo A.G.; Lorenzo, Manuel D.; Ramos-Gavilán, Ana B.; Sánchez-Haro, Javier; Lannou, Loïc; Bouchaïr, AbdelhamidTimber, as a sustainable and renewable building material, is becoming increasingly popular in modern architecture due to its aesthetic appeal, low environmental footprint, and structural ability. Glued-laminated timber (GLT) is commonly used for columns and beams in mid to high-rise buildings due to its strength and spanning ability. However, concerns about timber's combustibility raise safety concerns that demand the use of effective fire protection materials. One such method is the application of gypsum cladding, which provides thermal insulation and delays heat transfer to the timber, thus enhancing fire resistance. This study investigates the fire resistance of gypsum-protected GLT columns, focusing on the effects of geometry, load level, and cladding configuration. The European Charring Model (ECM) and the effective cross-section design method are used alongside with three experimental tests, full three-dimensional computational model and a parametric study. The results provide valuable insights into the thermal insulation performance of gypsum cladding, the charring behaviour of timber under fire, and the influence of different protection layers and load levels on overall fire performance. Under 36 % load level, doubling the protection layer, increases the fire resistance up to 95 %. Changing the material grade from GL24h to GL28h, increases the fire resistance, from 2 % to 12 %, depending on the slenderness of the column, while increasing the load level from 6 % to 36 % reduces the fire resistance up to 47 %. This research contributes to fire safety and supports the expanded use of engineered timber in sustainable building designs by improving knowledge of its fire performance characteristics.
- From a techno-economic towards a socio-technical approach—a review of the influences and policies on home energy renovations’ decisionsPublication . Abreu, Maria Isabel; Pereira, Andreia; Gervásio, HelenaOver the past decades, the debate on how to encourage energy efficiency in existing homes has been guided by a technic-economic model that has a strong focus on technologies and cost savings, in which human behavior has been devalued to a narrow behavioral economics overview. While this specific area of behavioral science enabled to capture of the dimension of energy renovations as a problem of homeowners’ individual choice, the collective and social aspects of energy efficiency are still largely overlooked on the energy policy agenda. With its emphasis on how social structures interpenetrate individual actions, social sciences offer additional insights that go beyond the identification of barrier-drivers underlying investment choices and also help to identify positive opportunities for renovation within the conditions of domestic and social life. Until recently, comprehensive behavioral aspects and the social dimension of home energy renovation have been ignored in policy initiatives, and the integration of complementary disciplines is only in its early stages. Based on a broad literature review, this paper aims to provide an up-to-date interdisciplinary perspective of the theoretical evolutionary background, which has been the support to gradually redefine and address the problems associated with energy improvements in homes.
- How to improve quality investingPublication . González, Luis Otero; Santomil, Pablo Durán; Vieito, João Paulo da Torre; Reboredo, Juan CarlosIn this article, we evaluate the relationship between quality investing combined with Economic Moat, ESG (Environmental, Social and Governance) and analyst opinions over the period 2014–2020 based on a data set comprising 803 US stocks. Performance is evaluated using several metrics (returns and alphas). Our results show that quality stocks measured by return on invested capital (ROIC) exhibit superior performance. The incorporation of competitive advantages allows a better discrimination among the classic high-quality strategies. Investment in stocks with quality and high ESG entails the payment of a premium but buying quality companies with Economic Moat makes up for this negative aspect. The results show how quality companies that have competitive advantages obtain a better future performance and are recognized by the market with a higher valuation. However, the markets may take time to recognize this value since the incorporation of the average Price-to-Price target (Analyst consensus) increases the future performance. JEL classification: G11; G14; G23
- An ICT-enhanced methodology for the characterization of vernacular built heritage at a regional scalePublication . Tapiero, Juan; Graus, Sandra; Khei, Soon; Silva, Dener; Conde, Otavio; Ferreira, Tiago Manuel; Ortega, Javier; Luso, Eduarda; Rodrigues, Hugo; Vasconçelos, GraçaThe characterization of vernacular buildings is crucial for understanding the historical, social, and cultural significance of a community. These buildings reflect a collective memory and result from a long adaptation process to the local environment. Documenting them facilitates better decision-making regarding the preservation of their intrinsic values and long-term conservation. Unfortunately, depopulation processes in many areas threaten this invaluable heritage. Furthermore, this heritage is often overlooked due to a lack of awareness and appreciation by local authorities and residents. This paper presents a methodology for documenting and inventorying vernacular built heritage, with the main goal of contributing to promoting its valorization. The methodology integrates Information and Communication Technologies (ICT) with GIS tools to create large-scale inventories. Using the Montesinho Natural Park (Portugal) as a case study, the methodology facilitated the collection of data from over 2,000 buildings in 13 villages. The collected data was then used to characterize the vernacular built heritage of selected villages in terms of authenticity, conservation state, materials, construction systems, past interventions, present use, and occupancy. The findings of this study can serve as a valuable resource for developing inventories of vernacular buildings in rural areas, contributing to the protection of this distinctive architectural heritage
- On‐site power generation using biogas in sewage treatment plants: a techno‐economic assessment of a brazilian UASB facilityPublication . Pérez, Nestor; Cabral, Edilson; Bimestre, Thiago; Loures, Carla; Maya, Diego; Ribeiro, Luís FrölénSmall sewage treatment plants (STPs) in developing regions often flare the biogas produced in their upflow anaerobic sludge blanket (UASB) reactors, giving away a cost-effective energy source. This study tests whether on-site biogas-to-energy can pay for itself in approximately 2 years, even in plants treating less than 30 l s−1. A small-scale STP in Angra dos Reis, Brazil (25 L/s), was studied, with an average biogas flow of 9.7 m3/h; electricity generation was modeled for an engine generator unit with an efficiency of 30%. The techno-economic results show that the actual system would generate 125 MWh/year at a levelized cost of 0.017–0.023 USD/kWh, covering 47% of the plant’s electricity demand. At a discount rate of 8%, the net present value was + 9.3 k US$, and the simple payback period was 2 years for the initial investment. Additionally, extrapolating the results to account for future expansion of the sewage treatment plant based on the total population in the region served by the system reveals even more promising results, with a suggested payback period of 1 year and 1 month of operation, covering approximately 57% of electricity demand. Scaling this retrofit to the approximately 18,000 comparable UASB-based STPs worldwide at low capital cost could reduce electricity bills by approximately 40% and avoid ~ 450 tons of CO2-eq. per plant per year through methane capture and displacement of electricity from the grid. These results confirm that decentralized biogas power generation on a small scale is not only technically feasible, but also financially attractive and ecologically beneficial for operators of sewage and wastewater treatment plants and municipalities.