University of Piraeus

About: University of Piraeus is a education organization based out in Piraeus, Attiki, Greece. It is known for research contribution in the topics: Context (language use) & Computer science. The organization has 1731 authors who have published 6209 publications receiving 106699 citations.

Biofuels: A Survey on Pros and Cons

Abstract: A survey of research findings focusing on issues related to the pros and cons of using biofuels to substitute conventional fuels, namely, fossil fuels is presented in this paper. This controversial topic has attracted great political, economic, and social attention because it is touching interests of world significance during recent years. The paper presents the main biofuel types that are used today or can be used in the future, their properties and characteristics, and their production technologies and focuses on the evaluation and main economic, environmental, and social impacts of biofuels, measuring the pros and cons of their use in energy production. The future of biofuels is also discussed. The paper is concluded with a discussion, some conclusions, and suggestions for further research.

Sentiment analysis of Facebook statuses using Naive Bayes classifier for language learning

Abstract: The growing expansion of contents, placed on the Web, provides a huge collection of textual resources. People share their experiences, opinions or simply talk just about whatever concerns them online. The large amount of available data attracts system developers, studying on automatic mining and analysis. In this paper, the primary and underlying idea is that the fact of knowing how people feel about certain topics can be considered as a classification task. People's feelings can be positive, negative or neutral. A sentiment is often represented in subtle or complex ways in a text. An online user can use a diverse range of other techniques to express his or her emotions. Apart from that, s/he may mix objective and subjective information about a certain topic. On top of that, data gathered from the World Wide Web often contain a lot of noise. Indeed, the task of automatic sentiment recognition in online text becomes more difficult for all the aforementioned reasons. Hence, we present how sentiment analysis can assist language learning, by stimulating the educational process and experimental results on the Naive Bayes Classifier.

Competence Models in Technology-Enhanced Competence-Based Learning

Abstract: Please cite as: Sampson, D., & Fytros, D. (2008). Competence Models in Technology-enhanced Competence-based Learning. In H. H. Adelsberger, Kinshuk, J. M. Pawlowski & D. Sampson (Eds.), International Handbook on Information Technologies for Education and Training, 2nd Edition, Springer, June 2008

Testing for causality-in-variance: an application to the East Asian markets

Abstract: In this paper we provide some empirical evidence on the casual relationship between stock prices and exchange rates volatility in four East Asian countries. In order to test for causality-in-variance, we use a GARCH model for which a BEKK representation is adopted, and then test for the relevant zero restrictions on the conditional variance parameters. We find that in the pre-crisis sample stock prices lead exchange rates negatively in Japan and South Korea (consistently with the portfolio approach) and positively in Indonesia and Thailand. In the latter two countries after the onset of the 1997 East Asian crisis the spillover effects are found to be bidirectional. Copyright © 2002 John Wiley & Sons, Ltd.