Charalampos Bratsas

Prof. Charalampos Bratsas

International Hellenic University, Thessaloníki, Kentrikí Makedonía, Greece
orcid

Research Focus & Metrics

Academic Career Length

22Years (2005-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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17 February 2010 in IEEE Transactions on Information Technology in Biomedicine
Verified
Journal Article
Closed access
Christos A. FrantzidisChristos A. Frantzidis
Christos A. Frantzidis
Charalampos BratsasCharalampos Bratsas
Charalampos Bratsas
CHRISTOS PAPADELISCHRISTOS PAPADELIS
CHRISTOS PAPADELIS
EKEvdokimos Konstantinidis
Evdokimos Konstantinidis
CPCostas Pappas
Costas Pappas
PANAGIOTIS BAMIDISPANAGIOTIS BAMIDIS
PANAGIOTIS BAMIDIS
This paper proposes a methodology for the robust classification of neurophysiological data into four emotional states collected during passive viewing of emotional evocative pictures selected from the International Affective Picture System. The proposed classification model is formed according to the current neuroscience trends, since it adopts the independency of two emotional dimensions, namely arousal and valence, as dictated by the bidirectional emotion theory, whereas it is gender-specific. A two-step classification procedure is proposed for the discrimination of emotional states between EEG signals evoked by pleasant and unpleasant stimuli, which also vary in their arousal/intensity levels. The first classification level involves the arousal discrimination. The valence discrimination is then performed. The Mahalanobis (MD) distance-based classifier and support vector machines (SVMs) were used for the discrimination of emotions. The achieved overall classification rates were 79.5% and 81.3% for the MD and SVM, respectively, significantly higher than in previous studies. The robust classification of objective emotional measures is the first step toward numerous applications within the sphere of human-computer interaction.

8 January 2010 in IEEE Transactions on Information Technology in Biomedicine
Verified
Journal Article
Closed access
Christos A. FrantzidisChristos A. Frantzidis
Christos A. Frantzidis
Charalampos BratsasCharalampos Bratsas
Charalampos Bratsas
MKManousos Klados
Manousos Klados
EKEvdokimos Konstantinidis
Evdokimos Konstantinidis
CLChrysa D. Lithari
Chrysa D. Lithari
PANAGIOTIS BAMIDISPANAGIOTIS BAMIDIS
PANAGIOTIS BAMIDIS
Recent neuroscience findings demonstrate the fundamental role of emotion in the maintenance of physical and mental health. In the present study, a novel architecture is proposed for the robust discrimination of emotional physiological signals evoked upon viewing pictures selected from the International Affective Picture System (IAPS). Biosignals are multichannel recordings from both the central and the autonomic nervous systems. Following the bidirectional emotion theory model, IAPS pictures are rated along two dimensions, namely, their valence and arousal. Following this model, biosignals in this paper are initially differentiated according to their valence dimension by means of a data mining approach, which is the C4.5 decision tree algorithm. Then, the valence and the gender information serve as an input to a Mahalanobis distance classifier, which dissects the data into high and low arousing. Results are described in Extensible Markup Language (XML) format, thereby accounting for platform independency, easy interconnectivity, and information exchange. The average recognition (success) rate was 77.68% for the discrimination of four emotional states, differing both in their arousal and valence dimension. It is, therefore, envisaged that the proposed approach holds promise for the efficient discrimination of negative and positive emotions, and it is hereby discussed how future developments may be steered to serve for affective healthcare applications, such as the monitoring of the elderly or chronically ill people.

23 December 2019 in Sustainability
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Journal Article
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Charalampos BratsasCharalampos Bratsas
Charalampos Bratsas
Kleanthis KoupidisKleanthis Koupidis
Kleanthis Koupidis
JGJosep Maria Salanova Grau
Josep Maria Salanova Grau
Konstantinos GiannakopoulosKonstantinos Giannakopoulos
Konstantinos Giannakopoulos
Aristeidis KaloudisAristeidis Kaloudis
Aristeidis Kaloudis
Georgia AifadopoulouGeorgia Aifadopoulou
Georgia Aifadopoulou
Rising interest in the field of Intelligent Transportation Systems combined with the increased availability of collected data allows the study of different methods for prevention of traffic congestion in cities. A common need in all of these methods is the use of traffic predictions for supporting planning and operation of the traffic lights and traffic management schemes. This paper focuses on comparing the forecasting effectiveness of three machine learning models, namely Random Forests, Support Vector Regression, and Multilayer Perceptron—in addition to Multiple Linear Regression—using probe data collected from the road network of Thessaloniki, Greece. The comparison was conducted with multiple tests clustered in three types of scenarios. The first scenario tests the algorithms on specific randomly selected dates on different randomly selected roads. The second scenario tests the algorithms on randomly selected roads over eight consecutive 15 min intervals; the third scenario tests the algorithms on random roads for the duration of a whole day. The experimental results show that while the Support Vector Regression model performs best at stable conditions with minor variations, the Multilayer Perceptron model adapts better to circumstances with greater variations, in addition to having the most near-zero errors.

1 June 2017 in Journal of Applied Journalism & Media Studies
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Journal Article
Closed access
AVAndreas Veglis
Andreas Veglis
Charalampos BratsasCharalampos Bratsas
Charalampos Bratsas
In the past, journalists were responsible for reporting the news. But today news stories disseminate as the incidents unfold, from multiple sources. Thus, gathering, filtering and visualizing events has a growing value. Huge amounts of data are available, but exploiting them is not an easy task. Data journalism can be defined as a journalism speciality in which numerical data are used in the production and distribution of information. This article investigates the necessary skills that journalists must have in order to cope with data journalism. More precisely, it defines data journalism, and discusses journalists’ Information and Communication Technology (ICT) skills, as well as the necessary skills for supporting data journalism. Special attention is given to Web 3.0 and open data that can play an important role in data journalism. A survey conducted among professional journalists in Greece concerning data journalism is also presented and discussed.

10 September 2017 in Journal of Media Critiques
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Andreas VeglisAndreas Veglis
Andreas Veglis
Charalampos BratsasCharalampos Bratsas
Charalampos Bratsas
TOWARDS A TAXONOMY OF DATA JOURNALISM

1 March 2016 in Biomedical Signal Processing and Control
Verified
Journal Article
Closed access
ISIoanna-Maria Spyrou
Ioanna-Maria Spyrou
CFChristos Frantzidis
Christos Frantzidis
Charalampos BratsasCharalampos Bratsas
Charalampos Bratsas
IAIoannis Antoniou
Ioannis Antoniou
PANAGIOTIS BAMIDISPANAGIOTIS BAMIDIS
PANAGIOTIS BAMIDIS