Abstract
Manuscript type: Research paper Research aims: This study aims to shed light on the factors that facilitate online purchase of perfume. It specifically: 1) explores the antecedents of online purchase behaviour in the case of experience goods; 2) analyses the motivations, perceived benefits and perceived risks associated with online purchase of perfume; and 3) identifies perfume e-shoppers' profiles. Design/Methodology/Approach: A qualitative research approach involving interviewing 27 perfume e-shoppers from Brazil, Iran and Portugal was adopted. Research findings: The findings of this study reveal that there are three types of perfume e-shoppers: 1) experienced e-shoppers, 2) bargain e-seekers, and 3) expert e-shoppers. Competitive prices, enjoyable online experiences and greater varieties of perfumes are among the perceived benefits that motivate the online shoppers. The inability to test the perfumes, particularly those that are never tried before, appears to be the major drawback. Theoretical contribution/Originality: This study provides interesting cues on a topic that has so far been disregarded by the literature despite its growing importance as a business sector-online purchase of perfumes. It offers the categorisation of three e-shopper profiles, based on consumers' narratives, and highlighted the importance of further addressing the dynamic nature of consumer behaviours, particularly in the online context. Practitioner/Policy implications: The findings show that the main trigger of buying perfume online is the price discounts, which is particularly important to less experienced Web shoppers. This indicates that experience goods such as perfume should, at the initial stage, be sold in stores that offer an assortment of products. Online perfume stores should consider alternatives to provide perfume testing. Research limitation/Implications: Purposive sampling does not allow results' generalisation; hence future research is needed to further validate the findings.

Abstract
In this paper the comparison between three convolutional neural networks, used for the control of bio-inspired multi-robots in a simulated environment, is performed through manual gestures captured in real time by a webcam. The neural networks are: VGG19, GoogLeNet and Alexnet. For the training of networks and control of robots, six gestures were used, each gesture corresponding to one action, collective and individual actions were defined, the simulation contains four bio-inspired robots. In this work the performance of the networks in the classification of gestures to control robots is compared. They proved to be efficient in the classification and control of agents, with Alexnet achieving an accuracy of 98.33%, VGG19 98.06% e Googlelenet 96.94%.

Abstract
Index structures were often used to optimise fetch operations to external storage devices (secondary memory). Nowadays, this also holds for increasingly large amounts of data residing in main-memory (primary memory). Within this scope, this work focuses on index structures that efficiently insert, query and delete valid-time data from very large datasets. This work performs a comparative study on the performance of the Interval B+ tree (IB+ tree) and the Improved Interval B+ tree (I2B+ tree): a variant that improves the time-efficiency of the deletion operation by reducing the number of traversed nodes to access siblings. We performed an extensive analysis of the performance of two operations: insertions and deletions, on both index structures, using multiple datasets with growing volumes of data, distinct temporal distributions and tree parameters (time-split alpha and node order). Results confirm that the I2B+ tree globally outperforms the IB+ tree, since, on average, deletion operations are 7% faster, despite insertions requiring 2% more time. Furthermore, results also allowed to determine the key factors that augment the performance difference on deletions between both trees. Copyright © 2021 by Author/s and Licensed by Veritas Publications Ltd., UK.

Abstract
In recent years and after the strong impact of the last global health emergency (COVID-19) information and communication technologies have had a great impact on society but particular in the teaching-learning process. Education has been impacted at all its levels. Therefore, education models have been to be adapted to this new challenging paradigm by using different tools such as videoconferences, simulations, on-line interactive applications, virtual and remote laboratories, robots, etc.The objective of this work is to elaborate a systematic mapping to know what scientific from its beginning to 2020, identifying the most literature exists regarding simulators, remote and virtual laboratories focused on STEM/STEAM skills development in the educational context. To do so, bibliographical data gathered of four of the most popular and complete electronic databases (ACM, IEEE, Scopus and Web of Science). At the begging we selected 1232 articles after applying the acceptance criteria defined as part of the search and select strategy, we had 61 articles that help us to answer some questions like what are the most popular virtual and remote labs? or what are the current trends and issues of these tools? and the future ones? © 2021 IEEE.

Abstract
Teaching project management and industrial optimization to engineering students requires real-world experiences in which they can explicitly integrate, apply and develop work-ready skills, such as critical thinking, communication, and teamwork. This paper presents an exploratory case study research describing an online Project-based Learning (PjBL) experience aimed at tackling the challenge of decreasing the ecological footprint in the university campus generated by the local locomotion of students from university-home and/or home-university. The experience was implemented from February to June 2020, in the middle of the COVID-19 pandemic, with 9 participating students enrolled in the 'Industrial Management I' course, part of the Master of Science in Mechanical Engineering at the University of Tras-os-Montes and Alto Douro (UTAD), Portugal. We firstly describe the course in terms of the key driving question, the learning goals, the educational activities, the collaboration among students, the scaffolding technologies, and the tangible artefacts produced. We further discuss the preliminary results of the study by taking into account the main tangible learning artefact produced by the students - a carpooling model proposal for the UTAD student community - as well as the data collected from a post, self-completion questionnaire on students' perceptions about the PjBL experience. Finally, we outline implications for the teaching practice and some concerns that need to be addressed in future course editions.

Abstract
This article proposes a series compensator with unbalanced voltage sag ride-through capability applied to grid-connected induction motors. A conventional three-phase voltage source inverter (VSI) is intended to regulate the motor voltages. The VSI is connected in series with the grid and a three-phase machine with open-ended windings. The proposed system is suitable for applications in which no frequency variation is required, like large pumps or fans. The VSI dc-link voltage operates as a floating capacitor through the energy minimized compensation (EMC) technique, in which there is no dc source or injection transformer. The motor load condition determines the minimum grid voltage positive component (sag severity) to keep EMC operation. Meanwhile, a voltage unbalance may increase the dc-link voltage requirements. A 1.5-hp four-pole induction motor has been used to verify the ride-through capability of the proposed compensator under grid voltage disturbances. A total harmonic distortion (THD) analysis of grid currents demonstrates that the proposed system provides low THD even if no passive filter is used. The operating principle, converter output voltage analysis, pulsewidth modulation technique, control strategy, and components ratings are discussed as well. Simulation and experimental results are presented to demonstrate the feasibility of the system.