Acceleration of physics simulation engine through OpenCL

Dissertação para obtenção do Grau de Mestre em Engenharia Informática

Estabilização de vídeos com base em descritores H.264

Dissertação para obtenção do Grau de Mestre em Engenharia Eletrotécnica e de Computadores

Reciprocity, inequity aversion, and oligopolistic competition

This paper studies how reciprocity and inequity aversion influence the behavior of firms in imperfectly competitive markets. The paper shows that if reciprocal firms compete à la Cournot, then they are able to sustain “collusive” outcomes under a positive reciprocity equilibrium. By contrast, Stackelberg warfare outcomes may emerge under a negative reciprocity equilibrium. The results for inequity aversion are similar. Cournot competition between inequity averse firms can be harmful to consumers if it leads to equilibria where firms feel compassion toward each other. However, in equilibria where inequity averse firms are envious of each other consumers are better off than if firms were selfish. The paper also shows that only under very restrictive conditions does reciprocity or inequity aversion have an impact on Bertrand competition. Finally, the paper shows that non-selfish preferences have a greater impact on equilibrium outcomes in markets with a small number of firms.

English Language Learning Inside and Outside the Classroom in Portugal

This study investigates the way of learning the English language in Portugal. First-year students of the faculty of Social Sciences and Humanities of New University of Lisbon were selected as participants in the case study. As data collection tools a questionnaire and focus-groups were used. 115 students completed the designed questionnaire and after that 12 students were selected for the more detailed focus-group discussions. Results of the research show that most part of the students´ English knowledge is received from outside the classroom by means of movies, songs, computer games, the Internet, communication with friends and other sources. Also, the results show that motivation is very important in language learning process and motivated students acquire the language faster and easier.

Social-media monitoring for cold-start recommendations

Generating personalized movie recommendations to users is a problem that most commonly relies on user-movie ratings. These ratings are generally used either to understand the user preferences or to recommend movies that users with similar rating patterns have rated highly. However, movie recommenders are often subject to the Cold-Start problem: new movies have not been rated by anyone, so, they will not be recommended to anyone; likewise, the preferences of new users who have not rated any movie cannot be learned. In parallel, Social-Media platforms, such as Twitter, collect great amounts of user feedback on movies, as these are very popular nowadays. This thesis proposes to explore feedback shared on Twitter to predict the popularity of new movies and show how it can be used to tackle the Cold-Start problem. It also proposes, at a finer grain, to explore the reputation of directors and actors on IMDb to tackle the Cold-Start problem. To assess these aspects, a Reputation-enhanced Recommendation Algorithm is implemented and evaluated on a crawled IMDb dataset with previous user ratings of old movies,together with Twitter data crawled from January 2014 to March 2014, to recommend 60 movies affected by the Cold-Start problem. Twitter revealed to be a strong reputation predictor, and the Reputation-enhanced Recommendation Algorithm improved over several baseline methods. Additionally, the algorithm also proved to be useful when recommending movies in an extreme Cold-Start scenario, where both new movies and users are affected by the Cold-Start problem.

Analysis of world economic variables using multidimensional scaling

Waves of globalization reflect the historical technical progress and modern economic growth. The dynamics of this process are here approached using the multidimensional scaling (MDS) methodology to analyze the evolution of GDP per capita, international trade openness, life expectancy, and education tertiary enrollment in 14 countries. MDS provides the appropriate theoretical concepts and the exact mathematical tools to describe the joint evolution of these indicators of economic growth, globalization, welfare and human development of the world economy from 1977 up to 2012. The polarization dance of countries enlightens the convergence paths, potential warfare and present-day rivalries in the global geopolitical scene.