Search results

The purpose of this study is to numerically and experimentally investigate the natural convection heat transfer in flat plates and plates with square, trapezoidal and triangular corrugations.

This work is an extension of the previous studies by Verderio et al. (2021a, 2021b, 2021c, 2021d, 2022a). An experimental apparatus was built to measure the plates’ temperatures during the natural convection cooling process. Several physical parameters were evaluated through the experimental methodology. Free and open-source computational tools were used to simulate the experimental conditions and to quantitatively and qualitatively evaluate the thermal plume characteristics over the plates.

The numerical results were experimentally validated with reasonable accuracy in the range of studied RaLP for the different plates. Empirical correlations of Nu¯LPexp=f(RaLP), h¯conv=f(RaLP) and Nu¯LPexp⋅(A/AP)=f(RaLP), with good accuracy and statistical representativeness, were obtained for the studied geometries. The convective thermal efficiency of corrugated plates (Δη), as a function of RaLP, was also experimentally studied quantitatively. In agreement with the findings of Oosthuizen and Garrett (2001), the experimental and numerical results proved that the increase in the heat exchange area of the corrugations has a greater influence on the convective exchange and the thermal efficiency than the disturbances caused in the flow (which reduce h¯conv). The plate with trapezoidal corrugations presented the highest convective thermal efficiency, followed by the plates with square and triangular corrugations. It was also proved that the thermal efficiency of corrugated plates increases with RaLP.

The results demonstrate that corrugated surfaces have greater thermal efficiency than flat plates in heating and/or cooling systems by natural convection. This way, corrugated plates can reduce the dependence on auxiliary forced convection systems, with application in technological areas and Industry 4.0.

The empirical correlations obtained for the corrected Nusselt number and thermal efficiency for the corrugated plate geometries studied are original and unpublished, as well as the experimental validation of the developed three-dimensional numerical code.

Introduction: Numerous decision-making situations are faced in education where Artificial Intelligence may be prevalent as a decision-making support tool to capture streams of learners’ behaviours.

Purpose: The purpose of the present study is to understand the role of AI in student performance assessment and explore the future role of AI in educational performance assessment.

Scope: The study tries to understand the adaptability of AI in the education sector for supporting the educator in automating assessment. It supports the educator to concentrate on core teaching-learning activities.

Objectives: To understand the AI adaption for educational assessment, the positives and negatives of confidential data collections, and challenges for implementation from the view of various stakeholders.

Methodology: The study is conceptual, and information has been collected from sources comprised of expert interactions, research publications, survey and Industry reports.

Findings: The use of AI in student performance assessment has helped in early predictions for the activities to be adopted by educators. Results of AI evaluations give the data that may be combined and understood to create visuals.

Research Implications: AI-based analytics helps in fast decision-making and adapting the teaching curriculum’s fast-changing industry needs. Students’ abilities, such as participation and resilience, and qualities, such as confidence and drive, may be appraised using AI assessment systems.

Theoretical Implication: Artificial intelligence-based evaluation gives instructors, students, and parents a continuous opinion on how students learn, the help they require, and their progress towards their learning objectives.

The purpose of this study is to numerically investigate the geometric influence of different corrugation profiles (rectangular, trapezoidal and triangular) of varying heights on the flow and the natural convection heat transfer process over isothermal plates.

This work is an extension and finalization of previous studies of the leading author. The numerical methodology was proposed and experimentally validated in previous studies. Using OpenFOAM® and other free and open-source numerical-computational tools, three-dimensional numerical models were built to simulate the flow and the natural convection heat transfer process over isothermal corrugation plates with variable and constant heights.

The influence of different geometric arrangements of corrugated plates on the flow and natural convection heat transfer over isothermal plates is investigated. The influence of the height ratio parameter, as well as the resulting concave and convex profiles, on the parameters average Nusselt number, corrected average Nusselt number and convective thermal efficiency gain, is analyzed. It is shown that the total convective heat transfer and the convective thermal efficiency gain increase with the increase of the height ratio. The numerical results confirm previous findings about the predominant effects on the predominant impact of increasing the heat transfer area on the thermal efficiency gain in corrugated surfaces, in contrast to the adverse effects caused on the flow. In corrugations with heights resulting in concave profiles, the geometry with triangular corrugations presented the highest total convection heat transfer, followed by trapezoidal and rectangular. For arrangements with the same area, it was demonstrated that corrugations of constant and variable height are approximately equivalent in terms of natural convection heat transfer.

The results allowed a better understanding of the flow characteristics and the natural convection heat transfer process over isothermal plates with corrugations of variable height. The advantages of the surfaces studied in terms of increasing convective thermal efficiency were demonstrated, with the potential to be used in cooling systems exclusively by natural convection (or with reduced dependence on forced convection cooling systems), including in technological applications of microelectronics, robotics, internet of things (IoT), artificial intelligence, information technology, industry 4.0, etc.

To the best of the authors’ knowledge, the results presented are new in the scientific literature. Unlike previous studies conducted by the leading author, this analysis specifically analyzed the natural convection phenomenon over plates with variable-height corrugations. The obtained results will contribute to projects to improve and optimize natural convection cooling systems.

The construction of learning scenarios is a way to plan for teaching activities, promoting the development of skills related to problem solving, collaboration, critical thinking and creativity. Using learning scenarios as a lesson planning strategy becomes a powerful tool in initial teacher education. On the one hand, it mobilizes teaching-related scientific concepts, and on the other hand, it offers opportunities to think on innovative pedagogic approaches involving strategies and capacities essential for the future teacher. Research shows that teacher education programs within real school contexts enriched with digital technologies represent an important factor in increasing the quality of teachers’ preparation and their future professional practice. The paper aims to discuss these issues.

The authors present the analysis of practice of design and implementation of learning scenarios in teachers’ initial education courses developed with students of teaching master degrees. Activity theory is used in the analysis of a case study of a student-teacher in Computer Science.

The results have been analyzed, contributing to the specification of the principles underlying the learning scenarios in initial teacher education.

Results show the affordances and possibilities of using learning scenarios as structuring resources for the initial teacher education practice.

Therefore, the use of learning scenarios brings a set of potentialities to teacher training given its prospective nature.

Organizational technologies can be classified according to the roles they play as either commodity or strategic. Commodity technologies support common operations, while strategic technologies address perceived threats to competitiveness, often identified by strategic foresight. These must go through an adoption process before playing an effective role in strategy execution. The adoption process includes known activities, ranging from sourcing (itself from in-house development to turn-key acquisition) to operational integration. This paper aims to reveal strategic technology adoption risks that arise during strategy execution.

A gradually developed causal loop diagram model, supported by general literature, introduces three general classes of technology adoption risks: mismatched requirements, supplier dependence and unmanaged life cycles.

Rather than managed, these risks are incurred or avoided depending on decisions made during the adoption process.

Despite the scarce literature coverage for the approach, examples revealing the presence of adoption risks are nevertheless available in the well-documented history of enterprise resource planning (ERP).

Although ERP is presented as a general-purpose strategic technology, the unique business features of maritime container terminals pose serious challenges to its adoption, which provides additional support to the discussion and reinforces the conclusions.

The approach to identifying risks in strategic technology adoption departs from the current risk paradigm in two significant ways. First, it emphasizes policy decision-making rather than external events. Second, it views risks as systemic rather than occurring independently.

The purpose of this paper is to evaluate four visualizations that represent affective states of students.

An empirical-experimental study approach was used to assess the usability of affective state visualizations in a learning context. The first study was conducted with students who had knowledge of visualization techniques (n=10). The insights from this pilot study were used to improve the interpretability and ease of use of the visualizations. The second study was conducted with the improved visualizations with students who had no or limited knowledge of visualization techniques (n=105).

The results indicate that usability, measured by perceived usefulness and insight, is overall acceptable. However, the findings also suggest that interpretability of some visualizations, in terms of the capability to support emotional awareness, still needs to be improved. The level of students’ awareness of their emotions during learning activities based on the visualization interpretation varied depending on previous knowledge of information visualization techniques. Awareness was found to be high for the most frequently experienced emotions and activities that were the most frustrating, but lower for more complex insights such as interpreting differences with peers. Furthermore, simpler visualizations resulted in better outcomes than more complex techniques.

Detection of affective states of students and visualizations of these states in computer-based learning environments have been proposed to support student awareness and improve learning. However, the evaluation of visualizations of these affective states with students to support awareness in real life settings is an open issue.

Part of the runway at Madeira Airport is a platform above the sea at a 60 m height, supported by a series of frames. When aircraft land on this section, a load is exerted on the structure, resulting in bending of the beams which constitute the frames. A vision-based monitoring system was devised and implemented to measure the deflection of the runway's beams when a landing occurs.

An area on the midspan of two beams, located on the area where aircraft are most likely to land, was prepared with a speckle pattern, and a camera was assembled above a column on each of the adjacent frames, enabling the computation of displacements using digital image correlation (DIC). The camera continuously acquires images of the monitored area and compares them to a reference using DIC. If a displacement is detected, a number of frames before and after this event are saved for further DIC processing.

The installed systems successfully detected several events corresponding to landings and, for each of those events, measured the deflection of the beams over time and computed displacement fields for critical images, with strain values obtained up to this point being too small to measure using the current system.

This work provides novel insights into the behaviour of a unique structure and constitutes the first use of a vision system in its structural monitoring operations. It is also a valuable development in the implementation of automated DIC monitoring systems in locations of difficult access.

The purpose of this paper is to evaluate the fatigue process through the dynamic analysis of the global structural model and local static sub-modelling in a critical detail using the hot-spot stress approach. The detail was studied in three different positions at the “Alcácer do Sal” access viaduct, and the methodologies from the IIW and Eurocode EN 1993-1-9 were compared.

In this study, the fatigue life process based on the hot-spot stress approach was evaluated using a global dynamic analysis and a local sub-modelling based on a static analysis of welded connections in the “Alcácer do Sal” railway structure, Portugal, taking into consideration the recommendations from IIW and Eurocode EN 1993-1-9. The hot-spot stresses were calculated through the static analysis of the sub-model of the welded connection for each vibration mode with the aim to obtain the temporal stresses using the modal coordinates and modal stresses of the extrapolation points. The Ansys® and Matlab® softwares were used for the numerical analysis and the hot-spot stress calculations, respectively.

The proposed methodology/approach to obtain fatigue assessment is based on the modal analysis of the global structural model and local static sub-modelling. The modal analysis was used to extract the boundary conditions to be used in the local model to determine the temporal stresses of the extrapolation points. Based on the modal superposition method, the stresses as function of time were obtained for fatigue life evaluation of a critical detail by the hot-spot stress approach. The detail was studied in three different positions.

In the present study, a global-local fatigue methodology based on dynamic analysis of the global structural model and local static sub-modelling of the critical detail using the hot-spot stress approach is proposed. Herein, the modal analysis of the global structural model supported by the modal superposition method was used to obtain the matrix of modal coordinates. The static analysis of the local sub-model for each mode from the modal analysis of global structural model was done to estimate the hot-spot stresses. The fatigue damage calculation was based on S-N curve of the critical detail and rainflow method. The IIW recommendation proved to be more conservative compared to the proposed rules in the Eurocode EN 1993-1-9. The global-local modelling based on dynamic analysis is an important and effective tool for fatigue evaluation in welded joints.

The purpose of this paper is to study the minimum necessary net internal area of dwellings that should be established by Portuguese building regulations.

The following tasks are carried out: selecting the furniture and equipment necessary for each dwelling; determining the size of furniture and equipment and its typical arrangement; conceiving models of functional spaces; determining the net area of functional spaces and dwellings; comparing results with statistics on housing construction in Portugal and with mandatory area standards used in Portugal and ten other European countries.

The paper finds that the net internal area presently set by Portuguese building regulations should be increased by 5 to 15 percent. The net internal area figure obtained by the study is similar to mandatory regulations established by some other European countries.

The study focuses on the net internal area of dwellings, although other space standards are also important to assuring the practicability of dwelling spaces; area standards were set on the basis of the current Portuguese situation and required adaptation when used in different social, cultural and economic contexts; area standards constitute a safety‐net against unacceptable dwellings rather than good practice guidelines.

The results may be used to support a review of Portuguese building regulations and provide guidelines for the design of dwellings.

A methodology to determine area standards is presented and applied. Up‐to‐date information on furniture size and arrangements is collected. The comparison enables an understanding of how the results compare in a European context.

As the size of the population is growing and the capacity of the planet Earth is limited, human beings are searching for sustainable and technology-enabled solutions to support society, ecology and economy. One of the solutions has been developing smart sustainable cities. Smart sustainable cities are cities as systems, where their infrastructure, different subsystems and different functional domains are virtually connected to the information and communication technologies (ICT) and internet via sensors and devices and the Internet of Things (IoT), to collect and process real-time Big Data and make efficient, effective and sustainable solutions for a democratic and liveable city for its various stakeholders. This chapter explores the concepts and practices of sustainable smart cities across the globe and explores the use of technologies such as IoT, Blockchain technology and Cloud computing, etc. their challenges and then presents a view on business models for sustainable smart cities.