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University of Rijeka

EducationRijeka, Croatia
About: University of Rijeka is a education organization based out in Rijeka, Croatia. It is known for research contribution in the topics: Population & Tourism. The organization has 3471 authors who have published 7993 publications receiving 110386 citations. The organization is also known as: Rijeka University & Sveučilište u Rijeci.


Papers
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Journal ArticleDOI
TL;DR: In this article, a pilot authentication study of Croatian extra virgin olive oils (EVOOs) was conducted using a combination of analytical methods based on chromatography, mass spectrometry and spectroscopy combined with chemometrics.
Abstract: Synergy of analytical methods based on chromatography, mass spectrometry and spectroscopy combined with chemometrics was tested in the herein presented pilot authentication study of Croatian extra virgin olive oils (EVOOs). Fatty acid (FA) composition was determined by gas chromatography-mass spectrometry (GC-MS), triacylglycerol (TAG) composition by matrix-assisted laser desorption ionization time-of-flight/mass spectrometry (MALDI-TOF/MS), and non-selective analysis was done by near-infrared spectroscopy (NIRS). Chemometric methods were applied on measured data where TAG and NIR spectra showed the highest potential for geographical origin discrimination. TAG profiling data had the best classification power for EVOOs in the PCA, whereas PLS-DA models with high classification accuracy were based on NIRS significant variables or TAG data. Furthermore, NIRS data proved valuable in prediction of quality parameters. Therefore, we presented NIRS as quick, cheap and reliable technique for authenticity study of EVOOs, but for complete characterization of olive oils MALDI-TOF/MS was indispensable.

49 citations

Journal ArticleDOI
Jelena Aleksić1, H. Anderhub2, L. A. Antonelli3, P. Antoranz4  +147 moreInstitutions (18)
TL;DR: The Major Atmospheric Gamma Imaging Cerenkov (MAGIC) telescope participated in three multi-wavelength (MWL) campaigns, observing the blazar Markarian (Mkn) 421 during the nights of April 28 and 29, 2006, and June 14, 2006.
Abstract: Context. Wide-range spectral coverage of blazar-type active galactic nuclei is of paramount importance for understanding the particle acceleration mechanisms assumed to take place in their jets. The Major Atmospheric Gamma Imaging Cerenkov (MAGIC) telescope participated in three multiwavelength (MWL) campaigns, observing the blazar Markarian (Mkn) 421 during the nights of April 28 and 29, 2006, and June 14, 2006. Aims. We analyzed the corresponding MAGIC very-high energy observations during 9 nights from April 22 to 30, 2006 and on June 14, 2006. We inferred light curves with sub-day resolution and night-by-night energy spectra. Methods. MAGIC detects gamma-rays by observing extended air showers in the atmosphere. The obtained air-shower images were analyzed using the standard MAGIC analysis chain. Results. A strong gamma-ray signal was detected from Mkn 421 on all observation nights. The flux (E > 250 GeV) varied on night-by-night basis between (0.92 +/- 0.11) x 10(-10) cm(-2) s(-1) (0.57 Crab units) and (3.21 +/- 0.15) x 10(-10) cm(-2) s(-1) (2.0 Crab units) in April 2006. There is a clear indication for intra-night variability with a doubling time of 36 +/- 10(stat) min on the night of April 29, 2006, establishing once more rapid flux variability for this object. For all individual nights gamma-ray spectra could be inferred, with power-law indices ranging from 1.66 to 2.47. We did not find statistically significant correlations between the spectral index and the flux state for individual nights. During the June 2006 campaign, a flux substantially lower than the one measured by the Whipple 10-m telescope four days later was found. Using a log-parabolic power law fit we deduced for some data sets the location of the spectral peak in the very-high energy regime. Our results confirm the indications of rising peak energy with increasing flux, as expected in leptonic acceleration models.

49 citations

Journal ArticleDOI
TL;DR: In this article, the authors present a comprehensive set of simulations of a single pulse and investigate the impact of the model parameters, related to the shock microphysics and to the initial conditions in the ejecta.
Abstract: Several trends have been identified in the prompt gamma-ray burst (GRB) emission: e.g. hard-to-soft evolution, pulse width evolution with energy, time lags, hardness-intensity/-fluence correlations. Recently Fermi has significantly extended the spectral coverage of GRB observations and improved the characterization of this spectral evolution. We study how internal shocks can reproduce these observations. In this model the emission comes from the synchrotron radiation of shock accelerated electrons, and the spectral evolution is governed by the evolution of the physical conditions in the shocked regions. We present a comprehensive set of simulations of a single pulse and investigate the impact of the model parameters, related to the shock microphysics and to the initial conditions in the ejecta. We find a general qualitative agreement between the model and the various observations used for the comparison. All these properties or relations are governed by the evolution of the peak energy and photon indices of the spectrum. In addition, we identify the conditions for a quantitative agreement. We find that the best agreement is obtained for (i) steep electron slopes (p>~2.7), (ii) microphysics parameters varying with shock conditions so that more electrons are accelerated in stronger shocks, (iii) steep variations of the initial Lorentz factor in the ejecta. When simulating short GRBs by contracting all timescales, all other parameters being unchanged, we show that the hardness-duration correlation is reproduced, as well as the evolution with duration of the pulse properties. Finally, we investigate the signature at high energy of these different scenarios and find distinct properties - delayed onset, longer emission, and flat spectrum in some cases - suggesting that internal shocks could have a significant contribution to the prompt LAT emission. [abridged]

49 citations

Journal ArticleDOI
TL;DR: In this paper, a wind turbine nozzle is designed as an aerodynamically shaped ring with wings with its lower pressure side pointed towards the center so that the lift force on each part of the wing is directed radially towards the centre.

49 citations

Journal ArticleDOI
TL;DR: In this article, a special simulation program has been developed for axially symmetric workpieces for the induction hardening of cylindrical workpiece made from the 42CrMo4 steel grade.

49 citations


Authors

Showing all 3537 results

NameH-indexPapersCitations
Igor Rudan142658103659
Nikola Godinovic1381469100018
Ivica Puljak134143697548
Damir Lelas133135493354
D. Mekterovic11044946779
Ulrich H. Koszinowski9628127709
Michele Doro7943720090
Robert Zivadinov7352218636
D. Dominis Prester7036316701
Daniel Ferenc7022516145
Vladimir Parpura6422618050
Stipan Jonjić6222719363
Dario Hrupec6028813345
Alessandro Laviano5929814609
Tomislav Terzić5827110699
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202329
202279
2021636
2020707
2019622
2018564