Percorrer por autor "Nunes, Sandra"
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- Durability of an UHPC containing spent equilibrium catalystPublication . Matos, Ana Mafalda; Nunes, Sandra; Costa, Carla; Aguiar, JoséUHPC is an advanced cementitious material able to meet the current construction industry challenges regarding structural safety and durability. However, new UHPC formulations with limited shrinkage are still being pursued to reduce residual tensile stresses in the UHPFRC layers, for rehabilitation/strengthening applications. This investigation estimates the durability of a non-proprietary UHPC incorporating a by-product originated by the oil refinery industry (ECat), as an internal curing agent. Direct and indirect transport properties measurements as well as the carbonation assessment and evaluation of dimensional resilience to potential deleterious reactions revealed that the new UHPC possesses an excellent durability performance, typical of these materials. These results combined with its self-compacting ability, low autogenous shrinkage and high compressive strength confirm the belief in the role of this new UHPC towards a high-tech construction.
- Gestão da imagem de destino: a perceção e os fatores de atração da Área Metropolitana de Lisboa entre estudantes universitáriosPublication . Severino, Filipe Segurado; Costa, Teresa; Cristina, Margarida; Roque, Ana Gláucia; Nunes, Sandra; Santos, Zelia RaposoEste estudo explora as perceções de estudantes universitários, tanto residentes portugueses como estudantes internacionais a viver em Lisboa, relativamente às principais atrações da Área Metropolitana de Lisboa, em Portugal. Estes estudantes, ao residirem atualmente em Lisboa, representam também potenciais turistas futuros. Compreender as suas perspetivas sobre as atrações de Lisboa visa fornecer contributos que possam orientar estratégias de destinos noutras regiões. Recorrendo a uma abordagem de métodos mistos, a investigação analisa as características específicas que atraem estes estudantes para Lisboa, cidade reconhecida pelo seu rico património cultural e ambiente vibrante. Os dados foram recolhidos junto de estudantes de duas instituições de ensino superior, através de questionários interativos com conteúdos multimédia sobre a área. O estudo destaca que os marcos culturais e históricos, as condições climáticas favoráveis e o compromisso com a sustentabilidade ecológica são elementos-chave que contribuem para a atratividade. Os resultados demonstram que estas características não só atraem potenciais turistas futuros, como também permitem aos destinos potenciar os seus atributos únicos para aumentar a atratividade e enfrentar os desafios da sustentabilidade. Esta análise aprofunda a compreensão das perceções dos turistas e das qualidades dos destinos, oferecendo contributos relevantes para iniciativas de gestão e marketing de destinos orientadas para práticas de turismo sustentável.
- An importance–performance analysis approach to a tourism destination: the case of Lisbon metropolitan area, PortugalPublication . Costa, Maria Teresa; Calisto, Maria de Lurdes; Santos, Zelia Raposo; Severino, Filipe Segurado; Nunes, Sandra; Rosário, João Ferreira doAbstract: Pull factors, the attributes of a specific location, matter in tourism. These factors encompass the distinctive characteristics and alluring features that attract tourists to a destination, their importance and performance influencing the decision-making process and overall experience. A clear comprehension of this concept is crucial for destinations' economic vitality as they compete for tourists and strive for economic expansion and employment prospects. Indeed, an in-depth knowledge of these factors' importance and performance underscores the need for regions to adjust their approach to evolving tourist preferences. This adaptation is crucial to fostering responsible and sustainable tourism practices that safeguard cultural and natural resources. However, besides learning about the factors considered critical by tourists to visit a location, it is paramount to analyse how they evaluate the performance of each of these factors while staying there.This study focuses on the Lisbon Metropolitan Area (LMA), Portugal, and the findings will provide essential insights into destination competitiveness, sustainable tourism development, and the creation of unique travel experiences. As a destination that gained popularity, attracting tourists from all over the world, it is necessary to comprehend the specific factors that contribute to this vibrant region's allure and how it performs regarding them. The research will use the Importance-Performance Analysis to make data interpretation accessible and suggest relevant measures to improve competitiveness based on optimising the allocation of resources among the various factors/attributes analysed. The research incorporates numerous criteria categories, including historical significance, urban appeal, natural scenery, culinary experiences, cultural heritage, and aspects like streets' cleanliness, transport availability, or health emergency infrastructures.The study's conclusions will impact Lisbon region's (LMA) tourism and destination management. By understanding what factors are more important for tourists that visit the area and their evaluation of the performance of each of these factors,stakeholders can improve marketing, infrastructure, and the visitors' experience to promote sustainable development and maintain Lisbon's standing as a top tourist destination for rewarding and enlightening experiences. Relevant data is also provided to inform future tourism initiatives. This study adds to the academic discussion of location competitiveness and unique travel experiences.
- The macro context for entrepreneurship in tourism: a review of emerging trendPublication . Costa, Maria Teresa; Calisto, Maria de Lurdes; Machado, Ana Teresa; Santos, Zelia Raposo; Nunes, Sandra; Severino, Filipe SeguradoAbstract: Tourism has an enormous economic and employment potential, which, at least until 2019, encouraged many countries to develop their tourism offer and attract more tourists. Then the COVID-19 pandemic happened, and nowadays, Europe, the most important tourism destination in the world, faces a new war and refugee crisis. Tourism is an activity that propels the economy and job creation internationally; nevertheless, the activity is vulnerable to macro environment events. Both aspects are crucial issues for tourism entrepreneurs. Therefore, it is relevant to understand the emerging trends that entrepreneurs may face. Based on a systematic literature review, this paper aims to identify the major macro-environmentalfactors that impact tourism activity by answering the following research question: What contextual factors should entrepreneurs expect to impact their businesses? A systematic literature review was conducted in three steps: 1) selection of the relevant sources (on WoS and Scopus-indexed journals) using appropriate selection criteria that fitted the research questions; 2) assessment of the selected articles according to exclusion criteria to reach a final sample of articles; 3) full analysis of the base of final articles to identify emerging trends associated to relevant contextual factors. Results suggest that political-legal, technological, sociocultural, and sustainability-related factors have been the most relevant ones. This study has relevant contributions to practice since it highlights what entrepreneurs should expect from the macro environment. It also contributes to tourism literature by opening new lines of research and synthesising the trends impacting tourism activity.
- Multi-level study on UHPFRC incorporating ECatPublication . Abrishambaf, Amin; Pimentel, Mário; Nunes, Sandra; Costa, CarlaThe suitability of a recently developed ultra-high performance fibre reinforced cementitious composite (UHPFRC) incorporating Spent Equilibrium Catalyst, ECat, for structural applications is investigated through a systematic multi-level investigation across micro, meso and composite levels. Scanning electron microscopy, isothermal calorimetry, thermogravimetric analysis, and mercury intrusion porosimetry tests were performed to evaluate the microstructure of the composite. At the meso-level, the mechanical properties of fibre to matrix ITZ were characterised by single fibre pullout tests on fibres embedded with various fibre orientation angles. At the composite level, specimens with 3% fibre content and different fibre orientation profiles were prepared to determine uniaxial tensile behaviour. The relation between the tensile fracture parameters and fibre structure parameter was assessed. In each level, the results are compared to a conventional ternary UHPFRC mixture and point towards the suitability of the newly developed mixture for structural applications.
- Numerical optimization of self-compacting mortar mixture containing spent equilibrium catalyst from oil refineryPublication . Nunes, Sandra; Costa, CarlaAs the oil refining industries continue to grow, the production of waste catalysts generated in that process is expected to also increase. It would be of great value both economically and ecologically if these wastes could be reused as an addition in self-compacting concrete (SCC). This paper uses statistical factorial design approach, namely a central composite design, to conduct a proper experimental plan to design SCC mortar mixtures incorporating spent equilibrium catalyst (ECat), a waste generated by the oil refinery industry. The mathematical empirical models derived (which were also experimentally validated) revealed the influence of mixture design parameters, and their coupled effects, on the mortars' properties namely, deformability, viscosity, compressive strength, resistivity and ultrasonic pulse velocity. A numerical optimization technique was applied to the derived models to select the best mixture, which maximizes simultaneously durability and eco-efficiency and minimize cost, while maintaining self-compactability. The current study revealed that ECat can be successfully applied in SCC mortars, as a high volume cement replacement material (up to V-Ecat/Vp = 19.7%) due to its high pozzolanic activity. Nevertheless, for powder-type SCC5, cement/ECat blends must be combined with other finer additions to complete the powders distribution curve increasing the viscosity and stability of paste phase, in the fresh state.
- Optimisation of hydraulic lime mortars incorporating an oil-refinery catalyst by-product for sustainable building rehabilitationPublication . Costa, Carla; Nunes, SandraAbstract This investigation employs a Central Composite Design-based Design of Experiments (DoE) methodology to develop hydraulic lime mortars incorporating equilibrium catalyst (ECat), a by-product generated at the fluid catalytic cracking unit in oil refineries. The derived mathematical models describe the quantitative effects of key mixing variables, specifically ECat content, water-to-binder ratio and water repellent dosage, as well as their cross-interactions, on mortar properties, namely workability, compressive strength, ultrasound propagation velocity and dynamic modulus of elasticity. Numerical optimisation techniques enabled the identification of optimal lime mortar compositions that maximise eco-efficiency while ensuring compliance with both regulatory and technological requirements for diverse masonry applications, including the rehabilitation of ancient buildings. Results confirm the by-product upcyclability of ECat, with feasible incorporation levels up to 56.6 % by mass, yielding mortars with significant potential for reducing the environmental impact of the built environment while advancing the circular economy and fostering technological innovation in the construction sector.
- Perceptions and realities of Lisbon: an examination of the image of a tourist destinationPublication . Severino, Filipe Segurado; Roque, Ana Gláucia; Cristina, Margarida; Santos, Zelia Raposo; Nunes, Sandra; Costa, TeresaAbstract Destination image is related to comprising cognitive, emotional, and conative components and includes an individual's thoughts, ideas, and perceptions of a place. Images consistently coincide with the internalisation of distinct perspectives, demonstrating that people have different perceptions of the destiny. Influences include media, authority figures, music, and movies. Although the experience may not match their initial expectations, these effects form their preconceived beliefs and expectations of a trip. Accordingly, it is important to explore the trustfulness of the positioning of tourist destinations to ascertain its alignment with the expectations of tourists. Given that, Lisbon has been regarded as one of the foremost European cities in recent years, owing to its high level of accessibility and its multifaceted sensory attributes, it was deemed pertinent to investigate the perceptions of the visitors towards the city. The present study used a mixed methods approach, incorporating a multimedia component that showcases various locations in the Lisbon region with open-ended questionnaires to gather the perspectives of the tourists and a closed-ended questionnaire that inquiries about the primary factors that attract visitors to Lisbon. This analysis employed graphical representations, including word clouds and graphics to explore the identified impressions. The research revealed a robust association between cultural, historical, and aesthetic variables and the choice of travel destination. Certain visual representations highlight the imperative of pursuing sustainable and responsible development to mitigate the potential for enduring degradation. This holds significance as certain images are linked to instances of environmental and social irresponsibility. The study also revealed that History and Heritage emerged as the most significant factors that attract individuals, followed by Cultural Attractions, Weather and Climate, Gastronomy, and Panoramic Views and Landscapes. A notable perception exists regarding the insufficiency of sustainability and eco-friendly practices, underscoring the necessity for targeted sustainability endeavours to promote responsible and sustainable development of tourism destinations. Indeed, additional research on the contrast of perception and reality at the location is needed to evaluate the picture provided to visitors. However, understanding tourist-relevant areas like Lisbon is a good foundation for advertising them, allowing various stakeholders to make authentic and valuable marketing decisions.
- SHIFT & Inspire: tourism & hospitality trendsPublication . Costa, Teresa; Calisto, Maria de Lurdes; Machado, Ana Teresa; Ramos, Célia Quitéria; Montargil, Filipe; Severino, Filipe Segurado; Ferreira do Rosário, João Carlos Vinagre; Umbelino, Jorge; Belo, Miguel; Madeira, Rui Neves; Nunes, Sandra; Santos, Zelia RaposoWelcome to “Shift & Inspire: Tourism and Hospitality Trends”, an e-book that explores the dynamic and ever-changing landscape of tourism and hospitality in a world undergoing profound transformation. As we embark on this journey, we delve into the diverse forces that shape the industry, touching upon crucial themes that are shaping the present and moulding the future.
- Spent equilibrium catalyst as internal curing agent in UHPFRCPublication . Matos, Ana Mafalda; Nunes, Sandra; Costa, Carla; Aguiar, J. B.The main goal of the current paper is to optimize ultra-high performance cementitious material (UHPC) mixes incorporating the spent equilibrium catalyst (ECat) to mitigate autogenous shrinkage. Design of experiments approach was used to optimize mixtures targeting different engineering properties, namely, self-compactibility, low early-age shrinkage and cracking risk, improved durability and high mechanical performance. The statistical models established indicated that ECat exhibits a strong positive effect on the autogenous shrinkage mitigation of UHPC attributed to the water absorbed in the porous of ECat particles. The proposed optimal UHPC mixture represents the best compromise between low autogenous shrinkage - 32% of reduction - and high resistivity at 28 days without impairing self-compatibility and compressive strength. This optimal UHPC combined with 3% high-strength steel fibres (l(f)/d(f) = 65) proved to be comparable to other Ultra High-Performance Fibre Reinforced Composites (UHPFRC), in terms of mechanical behaviour, and more eco-friendly and cost-efficient than UHPCs reported in the literature.