ESTiG - Artigos em Revistas Indexados à WoS/Scopus
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- Assessing the impact of working capital on free cash flow: evidence from portuguese accommodation companiesPublication . Fernandes, António B. ; Cardim, Sofia; Ferreira, Jessica; Pinto, Lígia; .This 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.
- Building resilient tourism systems: the strategic role of financial sustainability in portuguese tourism firmsPublication . Fernandes, António B. ; Ferreira, Jessica; Seidi, Fadiba; Cardim, Sofia; .This study examines the economic and financial sustainability of Portuguese tourism firms operating within Division 55 (Accommodation) and Division 56 (Food and Beverage Service Activities), using Return on Assets (ROA) as the central indicator of economic and financial sustainability to assess variations over time, across firm sizes and among regions. Drawing on a dataset of 8,735 firms and 113,559 observations from 2011 to 2023, the analysis relies on ROA due to its analytical robustness and suitability for longitudinal and cross-sectional comparison. Given the absence of normality and homogeneity of variances, robust statistical techniques were applied, namely Welch’s ANOVA and the Games-Howell post hoc test with bootstrapping, to ensure reliable inference. The findings reveal significant differences in financial sustainability over the study period, between firms of different sizes and across regions. Small firms record higher average ROA than micro, medium or large firms, while the Algarve emerges as the highest-performing region and the Autonomous Region of the Azores presents the weakest results. The study is limited by its exclusive reliance on quantitative financial indicators, without incorporating qualitative dimensions that might enrich understanding of sustainability drivers, and by the constraints posed by data non-normality. The results emphasise the need for policy measures tailored to regional characteristics and highlight the pivotal role of small firms in resilience in the tourism sector. The study adds value by providing a rigorous, longitudinal and regionally differentiated analysis of financial sustainability within the Portuguese tourism industry.
- Collaborative fault tolerance for cyber–physical systems: the diagnosis stagePublication . Piardi, Luís; Costa, Pedro; Schneider, André; Leitão, PauloThe reliability and robustness of cyber-physical systems (CPS) are critical aspects of the current industrial landscape. The high level of autonomous and distributed components associated with a large number of devices makes CPS prone to faults. Despite their importance and benefits, traditional fault tolerance methodologies, namely local and/or centralized, often overlook the potential benefits of collaboration between cyber-physical components. This paper introduces a collaborative fault diagnosis methodology for CPS, integrating self-fault diagnosis capabilities in agents and leveraging collaborative behavior to enhance fault diagnosis. The contribution of this paper relay in propose a methodology for fault diagnosis for CPS, based on multi-agent system (MAS) technology as a backbone of infra-structure, highlighting the components, agent behavior, functionalities, and interaction protocols, to explore the benefits of communication and collaboration between agents. The proposed methodology enhance the accuracy of fault diagnosis when compared with local approach. A case study was conducted in a laboratory-scale warehouse, focusing on diagnosing drift, bias, and precision faults in temperature and humidity sensors. Experimental results reveal that the collaborative methodology significantly outperforms the local approach in fault diagnosis, as evidenced by performance improvements in diagnosis classification. The statistical significance of these results was validated using the Wilcoxon signed-ranks test for paired samples.
- 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.
- An agent-based approach for implementing asset administration shell type 3Publication . Sakurada, Lucas; De la Prieta, Fernando; Leitão, PauloIndustry 4.0 (I4.0) is driving the digitization of traditional manufacturing systems toward intelligent and adaptable factories, where industrial assets are interconnected and capable of collaborating inside and cross-company to enhance production processes. A key enabler of this transition is the Asset Administration Shell (AAS), a standardized digital representation of an asset that encapsulates all asset-relevant information throughout its lifecycle. The AAS ensures that all assets, regardless of their type or function, can be seamlessly integrated into the I4.0, facilitating interoperability and efficient data exchange across the entire production network. However, traditional AAS solutions, namely AAS Types 1 and 2, cannot address all the requirements of modern industry environments. To overcome these limitations, the AAS Type 3 (proactive) extends beyond the conventional functionalities of traditional AAS by incorporating more sophisticated features, enabling I4.0 components to operate with greater autonomy, intelligence, and collaborative capabilities. While traditional AAS implementations (Types 1 and 2) have been widely studied and adopted, research on AAS Type 3 is still in its early stages, lacking formal specifications and standardized guidelines for its design and implementation. In this context, this article presents an agent-based AAS approach for implementing AAS Type 3, offering readers a clearer, more accessible description of its features and practical applicability while encouraging further research and development in this emerging topic. For this purpose, several experiments were performed to gain a better understanding of its application in industrial scenarios. Additionally, the article discusses the experiences, insights, limitations and future perspectives derived from the design and experimental implementation of the agent-based AAS approach.
- Exposure to occupational risks in a portuguese care-home for elderly people: a case studyPublication . Oliveira, Rui; Fidalgo, Sandra; Cardim, SofiaResidential Structures for the Elderly People (care homes) play an essential role in the social response to support aging populations, reflecting the growing rate of aging in Portugal. These services are carried out by people in different, specific professional categories exposed to labour risks that affect the workers' physical, mental, and social health. Analysing and assessing the risks inherent in the various jobs is key to controlling them and preventing accidents and occupational illnesses. This study involves analysing the risks to which workers in a care home are exposed and, consequently, the preventive measures best suited to eliminating and controlling risks. The methodology involves the application of a questionnaire drawn up based on bibliographical research duly adjusted for the different professional categories. Subsequently, through non-participant observation, the existing risks were surveyed and evaluated, with the other sources of information being duly considered. The results show the need for specific training for the organization's employees and the implementation of lesser used preventive measures, which require more significant investment and support for their application in similar care-home institutions.
- An attempt to predict temperature-time histories for large scale compartment fires: a parametric analysisPublication . Hachana, Romaissa; Benarous, Abdallah; Roudane, Mohamed; Piloto, Paulo A.G.The accurate prediction of thermal conditions within compartment fires poses a significant challenge for fire safety engineers. In fact, sprinkler design, exit sceneries, and collapse structure configurations are closely related to the temporal evolution of the temperature inside the compartments. Through a comprehensive review of existing methodologies and standards, this study attempts to contribute for advancing the state of the art in fire dynamics modelling. The work deals with a comparative analysis of various temperature-time formulations proposed in the literature, providing insights into the discrepancies between theoretical models and real-world standards. It investigates the influence of key factors namely, the opening factor, the fuel load density, and the walls effusivity, on temperature histories. The natural fire curve, such as EPFC leads towards real world planning requirements, allows for a more tailored and pragmatic assessment for large-scale compartment fires, compared to the standard curves. The analysis aims, through a case study, to provide designers and architects with a practical way that facilitates early-stage planning and allows for effective fire prevention implementations.
- Institutional trust as a driver of product boycotts in EuropePublication . Baptista, Nuno; Dos-Santos, Maria; Mata, Fernando; Silva, Natacha JesusDespite the significant growth in consumer boycotts, research has devoted insuffi- cient attention to the institutional factors that may motivate consumers to engage in such behaviour. This article aims to address this research gap. The main objective is to analyse the factors that affect consumer boycotts from an institutional sustainabil- ity perspective, by focusing on a specific dimension of institutional sustainability: institutional trust. Information and data came from the 2023 round of the European Social Survey, a cross-national survey covering 25 Countries. The article applies a binomial univariable logit model to test the influence of institutional trust and other potential drivers on boycott decisions and a multivariable binomial logistic regres- sion to explore possible interrelationship between independent variables. The results confirm that boycotts are affected by institutional trust and other factors including demographic and socio-economic characteristics of the consumers, consumers’ per- ception of ICT, satisfaction with public institutions, and consumers’ evaluation of personal well-being. This article contributes to political consumerism literature by focusing on the impact of institutional trust in boycotting behaviour. This relation- ship is underexplored in existing literature, since most literature researches con- sumer boycotts from a triple-bottom perspective and neglects the effects of the insti- tutional dimension of sustainability in consumer behaviour. The article brings new insights into the motivations of consumers at the political and institutional levels and opens new directions for future research to explore institutional sustainability related to the good practices of governance.
- Fire after earthquake assessment of 3D reinforced concrete structuresPublication . Ismail Haouach; Abdelhak Kada; Belkacem Lamri; Piloto, Paulo A.G.Despite that, an earthquake’s occurrence can lead to dramatic effects with significant damage in urban areas, including human and material losses. Fire after an earthquake amplifies the overall impact and becomes a catastrophic event. Most constructions in Algeria are made of reinforced concrete, and current regulations overlook fires after earthquakes. Structural designs are inadequate to handle such events. This study aims to investigate the behaviour of 3D reinforced concrete frames, as part of a residential building, designed according to internal codes, CBA93 and RPA99 v2003. This 3D RC structure is exposed to several load levels of its vertical load bearing capacity. The structural system is assumed to undergo seismic scenarios characterised by various levels of story drift and damage level types. The structure is then exposed to the standard fire ISO834 model. Numerical investigations are carried out for thermo-mechanical analysis using the finite element software ANSYS, taking into account geometric and material non-linearities. Results highlight the significant impact of vertical loads, story drifts, fire scenarios, and structural damage on a building’s response to fire following an earthquake. These factors collectively influence the collapse probabilities, underlining the importance of holistic risk assessment in structural design.
- Insulation strategies to enhance fire resistance in composite slabs with reduced carbon emissionsPublication . Ribeiro, O.G.N.; Piloto, Paulo A.G.; Gidrão, G.D.M.S.Composite slabs have gained popularity in modern high-rise construction due to their superior load-bearing capacity and reduced self-weight. The vulnerability of the unprotected steel deck under fire conditions poses serious challenges, as the rapid reduction in steel strength and stiffness can compromise structural resistance and accelerate fire spread. This study presents a comprehensive numerical simulation to assess the fire behaviour of a novel composite slab and a new proposal for a simplified method. Three insulation techniques are investigated: a steel shield for the thinner part, a steel shield with the cavity filled with mineral wool, and a mineral wool plate applied from below. The simplified method is proposed to evaluate the fire resistance using new empirical coefficients, recalibrated within the framework of the prEN 1994-1-2 to allow for precise temperature predictions in steel components under standard fire. The numerical model, validated against experimental results, shows that the steel shield insulation extends the time to reach critical temperatures by approximately 25%. In contrast, mineral wool insulation proved to be substantially more effective by reducing temperatures in the UPPER 2 region by up to 89% compared to uninsulated slabs, after 60 min of fire exposure. This significant temperature reduction increases the load-bearing capacity during 60 min of fire exposure by 29%, also resulting in a potential reduction of approximately 22% in carbon emissions. The findings underscore and highlight the potential of these insulation systems to enhance the overall safety and resilience of composite slabs under fire, offering valuable insights for structural fire design.