DSpace Communidade:
http://www.repositorio.ufop.br/jspui/handle/123456789/5262
2024-03-28T15:51:05ZEnhancing SSVEP-based BCI performance with GAN-generated EEG signals.
http://www.repositorio.ufop.br/jspui/handle/123456789/17887
Título: Enhancing SSVEP-based BCI performance with GAN-generated EEG signals.
Autor(es): Silva, Isac Lopes; Vargas, Guilherme Vettorazzi; Leite, Sarah Negreiros de Carvalho2023-01-01T00:00:00ZOn network backbone extraction for modeling online collective behavior.
http://www.repositorio.ufop.br/jspui/handle/123456789/16875
Título: On network backbone extraction for modeling online collective behavior.
Autor(es): Ferreira, Carlos Henrique Gomes; Ferreira, Fabrício Murai; Silva, Ana Paula Couto da; Trevisan, Martino; Vassio, Luca; Drago, Idilio; Mellia, Marco; Almeida, Jussara Marques de
Resumo: Collective user behavior in social media applications often drives several important online
and offline phenomena linked to the spread of opinions and information. Several studies
have focused on the analysis of such phenomena using networks to model user interactions, represented by edges. However, only a fraction of edges contribute to the actual
investigation. Even worse, the often large number of non-relevant edges may obfuscate the
salient interactions, blurring the underlying structures and user communities that capture
the collective behavior patterns driving the target phenomenon. To solve this issue,
researchers have proposed several network backbone extraction techniques to obtain a
reduced and representative version of the network that better explains the phenomenon of
interest. Each technique has its specific assumptions and procedure to extract the backbone. However, the literature lacks a clear methodology to highlight such assumptions, discuss how they affect the choice of a method and offer validation strategies in scenarios
where no ground truth exists. In this work, we fill this gap by proposing a principled methodology for comparing and selecting the most appropriate backbone extraction method given
a phenomenon of interest. We characterize ten state-of-the-art techniques in terms of their
assumptions, requirements, and other aspects that one must consider to apply them in practice. We present four steps to apply, evaluate and select the best method(s) to a given target
phenomenon. We validate our approach using two case studies with different requirements:
online discussions on Instagram and coordinated behavior in WhatsApp groups. We show
that each method can produce very different backbones, underlying that the choice of an
adequate method is of utmost importance to reveal valuable knowledge about the particular
phenomenon under investigation.2022-01-01T00:00:00ZWatershed-ng : an extensible distributed stream processing framework.
http://www.repositorio.ufop.br/jspui/handle/123456789/16842
Título: Watershed-ng : an extensible distributed stream processing framework.
Autor(es): Rocha, Rodrigo; Hott, Bruno; Dias, Vinícius; Ferreira, Renato; Meira Júnior, Wagner; Guedes Neto, Dorgival Olavo
Resumo: Most high-performance data processing (a.k.a. big data) systems allow users to express their computation
using abstractions (like MapReduce), which simplify the extraction of parallelism from applications. Most
frameworks, however, do not allow users to specify how communication must take place: That element is
deeply embedded into the run-time system abstractions, making changes hard to implement. In this work, we
describe Wathershed-ng, our re-engineering of the Watershed system, a framework based on the filter–stream
paradigm and originally focused on continuous stream processing. Like other big-data environments,
Watershed provided object-oriented abstractions to express computation (filters), but the implementation
of streams was a run-time system element. By isolating stream functionality into appropriate classes,
combination of communication patterns and reuse of common message handling functions (like compression
and blocking) become possible. The new architecture even allows the design of new communication patterns,
for example, allowing users to choose MPI, TCP, or shared memory implementations of communication
channels as their problem demands. Applications designed for the new interface showed reductions in
code size on the order of 50% and above in some cases. The performance results also showed significant
improvements, because some implementation bottlenecks were removed in the re-engineering process.2016-01-01T00:00:00ZA fix-and-optimize heuristic for the ITC2021 sports timetabling problem.
http://www.repositorio.ufop.br/jspui/handle/123456789/16841
Título: A fix-and-optimize heuristic for the ITC2021 sports timetabling problem.
Autor(es): Fonseca, George Henrique Godim da; Toffolo, Túlio Ângelo Machado
Resumo: This paper addresses the general and challenging Sports Timetabling Problem proposed during the International Timetabling
Competition of 2021 (ITC2021). The problem is expressed in a flexible format which enables modeling a number of real-world
constraints that often occur in Sports Timetabling. An integer programming (IP) formulation and a fix-and-optimize heuristic
are proposed to address the problem. The fix-and-optimize approach uses the IP formulation to heuristically decompose the
problem into sub-problems and efficiently search on very large neighborhoods. The diverse ITC2021 benchmark instances
were used to evaluate the proposed methods. The formulation resulted in proven optimal solutions for two instances. However,
it failed to produce feasible solutions for most instances. The proposed fix-and-optimize, which uses an automatic sub-problem
size calibration strategy, resulted in feasible solutions for 37 out of the 45 ITC2021 instances. Among these solutions, four
are the best known in the literature. The proposed approach participated in the ITC2021 and was one of the finalists.2022-01-01T00:00:00Z