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In recent years robots have been used as a tool for teaching purposes, motivating the development of fully virtual environments for combined real/simulated robotics teaching. The AlphaBot2 Raspberry Pi (RPi), a robot used for education, has no currently available simulator. A Gazebo simulator was produced and a ROS framework was implemented for hardware abstraction and control of low-level modules facilitating students control of the robot's physical behaviours in the real and simulated robot, simultaneously. For the demonstration of the basic model operation, an algorithm for detection of obstacles and lines was implemented for the IR sensors, however, some discrepancies in a line track timed test were detected justifying the need for further work in modelling and performance assessment. Despite that, the implemented ROS structure was verified to be functional in the simulation and the real AlphaBot2 for its motion control, through the input sensors and camera.

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This paper explores the connections between the classical maximum clique problem and its edge-weighted generalization, the maximum edge weight clique (MEWC) problem. As a result, a new analytic upper bound on the clique number of a graph is obtained and an exact algorithm for solving the MEWC problem is developed. The bound on the clique number is derived using a Lagrangian relaxation of an integer (linear) programming formulation of the MEWC problem. Furthermore, coloring-based bounds on the clique number are used in a novel upper-bounding scheme for the MEWC problem. This scheme is employed within a combinatorial branch-and-bound framework, yielding an exact algorithm for the MEWC problem. Results of computational experiments demonstrate a superior performance of the proposed algorithm compared with existing approaches.

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Portugal is a country in which the tourism sector assumes great importance, contributing around 15% of the national GDP and with more than 1 million jobs. In this sense, COVID-19 is expected to have a dramatic impact on the Portuguese economy aggravated by the existence of a reduced internal market with low purchasing power and in which there is a high dependence on the external market. This perspective study explores the challenges and opportunities that Portuguese companies in the field of tourism are facing due to the emergence of this pandemic. The challenges faced by companies are both short-term and long-term. In the short term, it is essential to ensure sufficient liquidity to reopen activities and in the long term, it is necessary to be prepared and reactive to disruptive movements that may arise in tourist demand. However, it is also important to recognize that some opportunities can be exploited, such as the quality of the health response, the exploitation of a less mass tourism supply based on the components of social and environmental sustainability, the increase of tourism among the elderly population from countries with greater purchasing power and the acceleration of the digitalization of tourism operations.

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Tourism is an industry, very focused on economic growth, with significant negative environmental and social impacts. Consequently, the tourism industry faces major challenges related to sustainability. Sustainable innovation is a tool that contributes not only to increased business competitiveness but can also play an important role in mitigating the negative impacts that such growth can generate. Recognizing the opportunity that this innovation can have in the tourism industry, this chapter analyzes the state of the art and systematizes the knowledge and evolution of the academic debate about this relationship between sustainable innovation and tourism from 1992 to 2018. This chapter indicates that sustainable tourism is focused on seven major areas of research and predominantly analyzed through quantitative methods. It is still an embryonic topic with scarce research done in several areas, such as the monitoring of its impacts, the effects felt by the communities of tourist destinations, and the impacts that sustainable innovation may have on other tourism subsectors. © 2020, IGI Global.

Abstract