Marko Njirjak

Dr. Marko Njirjak

University of Rijeka, Faculty of Engineering, Rijeka, Primorsko-Goranska Županija, Croatia
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Research Focus & Metrics

Academic Career Length

7Years (2020-Present)

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

Representative Publications

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1 March 2022 in Knowledge-Based Systems
Verified
Journal Article
Closed access
EOErik Otović
Erik Otović
Marko NjirjakMarko Njirjak
Marko Njirjak
DJDario Jozinović
Dario Jozinović
GMGoran Mauša
Goran Mauša
AMAlberto Michelini
Alberto Michelini
ISIvan S̆tAjduhar
Ivan S̆tAjduhar

19 November 2024 in Nature Machine Intelligence
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Journal Article
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Marko NjirjakMarko Njirjak
Marko Njirjak
LŽLucija Žužić
Lucija Žužić
MBMarko Babić
Marko Babić
PJPatrizia Janković
Patrizia Janković
EOErik Otović
Erik Otović
GMGoran Mauša
Goran Mauša

15 June 2022 in Journal of Chemical Information and Modeling
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Journal Article
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EOErik Otović
Erik Otović
Marko NjirjakMarko Njirjak
Marko Njirjak
DKDaniela Kalafatovic
Daniela Kalafatovic
GMGoran Mauša
Goran Mauša

17 March 2022 in Mathematics
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Journal Article
Open access
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Marko NjirjakMarko Njirjak
Marko Njirjak
EOErik Otović
Erik Otović
DJDario Jozinović
Dario Jozinović
JLJonatan Lerga
Jonatan Lerga
GMGoran Mauša
Goran Mauša
Ivan ŠtajduharIvan Štajduhar
Ivan Štajduhar
Non-stationary signals are often analyzed using raw waveform data or spectrograms of those data; however, the possibility of alternative time–frequency representations being more informative than the original data or spectrograms is yet to be investigated. This paper tested whether alternative time–frequency representations could be more informative for machine learning classification of seismological data. The mentioned hypothesis was evaluated by training three well-established convolutional neural networks using nine time–frequency representations. The results were compared to the base model, which was trained on the raw waveform data. The signals that were used in the experiment are three-component seismogram instances from the Local Earthquakes and Noise DataBase (LEN-DB). The results demonstrate that Pseudo Wigner–Ville and Wigner–Ville time–frequency representations yield significantly better results than the base model, while spectrogram and Margenau–Hill perform significantly worse (p < 0.01). Interestingly, the spectrogram, which is often used in signal analysis, had inferior performance when compared to the base model. The findings presented in this research could have notable impacts in the fields of geophysics and seismology as the phenomena that were previously hidden in the seismic noise are now more easily identified. Furthermore, the results indicate that applying Pseudo Wigner–Ville or Wigner–Ville time–frequency representations could result in a large increase in earthquakes in the catalogs and lessen the need to add new stations with an overall reduction in the costs. Finally, the proposed approach of extracting valuable information through time–frequency representations could be applied in other domains as well, such as electroencephalogram and electrocardiogram signal analysis, speech recognition, gravitational waves investigation, and so on.

23 August 2023 in MRS Advances
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Journal Article
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GMGoran Mauša
Goran Mauša
Marko NjirjakMarko Njirjak
Marko Njirjak
EOErik Otović
Erik Otović
DKDaniela Kalafatovic
Daniela Kalafatovic

17 September 2020
Verified
Conference Paper
Closed access
EOErik Otovic
Erik Otovic
Marko NjirjakMarko Njirjak
Marko Njirjak
IZIvana Zuzic
Ivana Zuzic
DKDaniela Kalafatovic
Daniela Kalafatovic
GMGoran Mauša
Goran Mauša