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Publicações

Publicações por LIAAD

2020

Prediction of Viticulture Farms Behaviour: An Agent-Based Model Approach

Autores
Galindro, A; Matias, J; Cerveira, A; Santos, C; Marta Costa, A;

Publicação
Palgrave Studies of Cross-Disciplinary Business Research, in Association with EuroMed Academy of Business

Abstract
The wine industry has a high business volume and adds value to the economy. This chapter intends to predict the wine firm performance of three of the most relevant Portuguese regions, by resorting to data available on the Portuguese Farm Accountancy Data Network (PTFADN, Resultados médios por exploração. Available on http://www.gpp.pt/index.php/rica/rede-de-informacao-de-contabilidades-agricolas-rica. Accessed 13 Mar 2018, 2001–2015). The existing social, economic and environmental parameters allowed us to perform function fitting with MATLAB, in order to attain information about the variable’s behaviour. Through the Agent-Based Model (ABM) simulations, it is possible to realize that, in general, the Alentejo region is substantially well prepared to deal with negative scenarios when compared with North and Central regions. Alternative scenarios can be performed in order to develop overall governmental policy recommendations, so as to ensure the sustainability of the three regions. © 2020, The Author(s).

2020

A Mathematical Model for Vineyard Replacement with Nonlinear Binary Control Optimization

Autores
Galindro, A; Cerveira, A; Torres, DFM; Matias, J; Marta Costa, A;

Publicação
Discontinuity, Nonlinearity, and Complexity

Abstract
Vineyard replacement is a common practice in every wine-growing farm since the grapevine production decays over time and requires a new vine to ensure the business sustainability. In this paper, we formulate a simple discrete model that captures the vineyard’s main dynamics such as production values and grape quality. Then, by applying binary non-linear programming methods to find the vineyard replacement trigger, we seek the optimal solution concerning different governmental subsidies to the target producer.

2020

Identifying journalistically relevant social media texts using human and automatic methodologies

Autores
Guimaraes, N; Miranda, F; Figueira, A;

Publicação
INTERNATIONAL JOURNAL OF GRID AND UTILITY COMPUTING

Abstract
Social networks have provided the means for constant connectivity and fast information dissemination. In addition, real-time posting allows a new form of citizen journalism, where users can report events from a witness perspective. Therefore, information propagates through the network at a faster pace than traditional media reports it. However, relevant information is a small percentage of all the content shared. Our goal is to develop and evaluate models that can automatically detect journalistic relevance. To do it, we need solid and reliable ground truth data with a significantly large quantity of annotated posts, so that the models can learn to detect relevance over all the spectrum. In this article, we present and confront two different methodologies: an automatic and a human approach. Results on a test data set labelled by experts' show that the models trained with automatic methodology tend to perform better in contrast to the ones trained using human annotated data.

2020

Analysis and Detection of Unreliable Users in Twitter: Two Case Studies

Autores
Guimaraes, N; Figueira, A; Torgo, L;

Publicação
Communications in Computer and Information Science

Abstract
The emergence of online social networks provided users with an easy way to publish and disseminate content, reaching broader audiences than previous platforms (such as blogs or personal websites) allowed. However, malicious users started to take advantage of these features to disseminate unreliable content through the network like false information, extremely biased opinions, or hate speech. Consequently, it becomes crucial to try to detect these users at an early stage to avoid the propagation of unreliable content in social networks’ ecosystems. In this work, we introduce a methodology to extract large corpus of unreliable posts using Twitter and two databases of unreliable websites (OpenSources and Media Bias Fact Check). In addition, we present an analysis of the content and users that publish and share several types of unreliable content. Finally, we develop supervised models to classify a twitter account according to its reliability. The experiments conducted using two different data sets show performance above 94% using Decision Trees as the learning algorithm. These experiments, although with some limitations, provide some encouraging results for future research on detecting unreliable accounts on social networks. © 2020, Springer Nature Switzerland AG.

2020

Knowledge-based Reliability Metrics for Social Media Accounts

Autores
Guimarães, N; Figueira, A; Torgo, L;

Publicação
Proceedings of the 16th International Conference on Web Information Systems and Technologies, WEBIST 2020, Budapest, Hungary, November 3-5, 2020.

Abstract
The growth of social media as an information medium without restrictive measures on the creation of new accounts led to the rise of malicious agents with the intend to diffuse unreliable information in the network, ultimately affecting the perception of users in important topics such as political and health issues. Although the problem is being tackled within the domain of bot detection, the impact of studies in this area is still limited due to 1) not all accounts that spread unreliable content are bots, 2) human-operated accounts are also responsible for the diffusion of unreliable information and 3) bot accounts are not always malicious (e.g. news aggregators). Also, most of these methods are based on supervised models that required annotated data and updates to maintain their performance through time. In this work, we build a framework and develop knowledge-based metrics to complement the current research in bot detection and characterize the impact and behavior of a Twitter account, independently of the way it is operated (human or bot). We proceed to analyze a sample of the accounts using the metrics proposed and evaluate the necessity of these metrics by comparing them with the scores from a bot detection system. The results show that the metrics can characterize different degrees of unreliable accounts, from unreliable bot accounts with a high number of followers to human-operated accounts that also spread unreliable content (but with less impact on the network). Furthermore, evaluating a sample of the accounts with a bot detection system shown that bots compose around 11% of the sample of unreliable accounts extracted and that the bot score is not correlated with the proposed metrics. In addition, the accounts that achieve the highest values in our metrics present different characteristics than the ones that achieve the highest bot score. This provides evidence on the usefulness of our metrics in the evaluation of unreliable accounts in social networks. Copyright

2020

Understanding Service Design and Design Thinking Differences Between Research and Practice: An Empirical Study

Autores
Torres, A; Miranda, C;

Publicação
EXPLORING SERVICE SCIENCE (IESS 2020)

Abstract
Service Design (SD) and Design Thinking (DT) evolved in the last decade and have become popular in the research field of service science. However, the application of SD and DT research outcomes into practice is still scarce. To help understanding the differences between research and practice, we conducted 20 semi-structured interviews with professionals and trainees from four organizations that are involved in service innovation projects. The results reveal several similarities and complementarities, (dis)advantages, requests and obstacles, which hinder companies from implementing and using structured SD and DT approaches. The findings present some challenges for both researchers and practitioners on actions they could take to overcome barriers and foster the SD and DT practice within organizations.

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