Faculty of Science, Kragujevac

Permanent URI for this collectionhttps://dspace.unic.kg.ac.rs/handle/123456789/8214

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The Faculty of Science in Kragujevac is constantly evolving and is one of the leading members of the University of Kragujevac. Based on the results of scientific research and pedagogical work of its professors and staff, it is highly ranked among the leading universities in Serbia, with a dedicated and strong international cooperation. The state of Serbia and its Ministry of Education and Science provide great support and assistance to the development of the Faculty of Science and the entire University.

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Stern-Gerlach Experiment’s Interpretations and Noether’s Theorem
(2011) Ristić, Vladimir M.; Radulović, Mirko M.; Miladinovic, Tatjana B.
In this paper we suggest that theories treating two interacting objects in a different manner (for instance electromagnetic field of a laser classically, and the interacting atom as a quantum object) should be called “mixed”. Mixed theories are not so rare in Physics. One just should look at the whole area of Atomic, Molecular and Optical Physics in which mixed theories are often used, and, also, theories including quantum object interacting with classical surroundings that are the subject of our present discussion: the field of Quantum decoherence, when applied to resolving the dilemma should classical trajectories be used in explaining the Stern-Gerlach experiment or not. Consequently we are proving one improved corollary to Noether’s theorem, stating that mixed theories are not supporting the law of conservation of angular momentum and spin, as they are not based on the isotropy of space-time.
Research on the fauna of earthworms (Annelida: Oligochaeta) of Sokobanja.
(2021) Sekulić, Jovana; Stojanovic, Mirjana; Trakić, Tanja; Popovic, Filip; Cvijanović, Gorica
Elastic grid resource provisioning with WoBinGO: A parallel framework for genetic algorithm based optimization
(Elsevier BV, 2015-01) Ivanović, Miloš; Simic, Visnja; Stojanovic, Boban; Kaplarević-Mališić, Ana; Marovic, Branko
In this paper, we present the WoBinGO (Work Binder Genetic algorithm based Optimization) framework for solving optimization problems over a Grid. It overcomes the shortcomings of earlier static pilot-job frameworks, by: (1) providing elastic resource provisioning thus avoiding unnecessary occupation of Grid resources; (2) providing friendliness towards other batching queue users thanks to adaptive allocation of jobs with limited lifetime. It hides the complexity of the underlying Grid environment, allowing the users to concentrate on the optimization problems. Theoretical analysis of possible speed-up is presented. An empirical study using an artificial problem, as well as a real-world calibration problem of a leakage model at the Visegrad power plant were performed. The obtained results show that despite WoBinGO’s adaptive and frugal allocation of computing resources, it provides significant speed-up when dealing with problems that have computationally expensive evaluations. Moreover, the benchmarks were performed in order to estimate the influence of the limited job lifetime feature on the queuing time of other batching jobs, compared to a static pilot-job infrastructure.
Learning domain invariant representations of heterogeneous image data
(2023) Ivanović, Miloš; Obrenović, Mihailo; Lampert, Thomas; Gançarski, Pierre
Supervised deep learning requires a huge amount of reference data, which is often difficult and expensive to obtain. Domain adaptation helps with this problem—labelled data from one dataset should help in learning on another unlabelled or scarcely labelled dataset. In remote sensing, where a variety of sensors produce images of different modalities and with different numbers of channels, it would be very beneficial to develop heterogeneous domain adaptation methods that are able to work between domains that come from different input spaces. However, this challenging problem is rarely addressed, the majority of existing heterogeneous domain adaptation work does not use raw image-data, or they rely on translation from one domain to the other, therefore ignoring domain-invariant feature extraction approaches. This article proposes novel approaches for heterogeneous image domain adaptation for both the semi-supervised and unsupervised settings. These are based on extracting domain invariant features using deep adversarial learning. For the unsupervised domain adaptation case, the impact of pseudo-labelling is also investigated. We evaluate on two heterogeneous remote sensing datasets, one being RGB, and the other multispectral, for the task of land-cover patch classification, and also on a standard computer vision benchmark of RGB-depth map object classification. The results show that the proposed domain invariant approach consistently outperforms the competing methods based on image-to-image/feature translation, in both remote sensing and in a standard computer vision problem.
The critical Barkhausen avalanches in thin random-field ferromagnets with an open boundary
(2019-04-19) Tadić, Bosiljka; Mijatović, Svetislav; Janicevic, Sanja; Spasojević, Djordje; Rodgers, Geoff J
The interplay between the critical fluctuations and the sample geometry is investigated numerically using thin random-field ferromagnets exhibiting the field-driven magnetisation reversal on the hysteresis loop. The system is studied along the theoretical critical line in the plane of random-field disorder and thickness. The thickness is varied to consider samples of various geometry between a two-dimensional plane and a complete three-dimensional lattice with an open boundary in the direction of the growing thickness. We perform a multi-fractal analysis of the Barkhausen noise signals and scaling of the critical avalanches of the domain wall motion. Our results reveal that, for sufficiently small thickness, the sample geometry profoundly affects the dynamics by modifying the spectral segments that represent small fluctuations and promoting the time-scale dependent multi-fractality. Meanwhile, the avalanche distributions display two distinct power-law regions, in contrast to those in the two-dimensional limit, and the average avalanche shapes are asymmetric. With increasing thickness, the scaling characteristics and the multi-fractal spectrum in thicker samples gradually approach the hysteresis loop criticality in three-dimensional systems. Thin ferromagnetic films are growing in importance technologically, and our results illustrate some new features of the domain wall dynamics induced by magnetisation reversal in these systems.
Stefan PINN-GA
(2023-03-14) Kaplarević-Mališić, Ana; Andrijević, Branka; Bojović, Filip; Nikolić, Srđan; Krstić, Lazar; Stojanović, Boban; Ivanović, Miloš
Stefan PINN GA
Neuronske mreže podržane fizičkim zakonima - Praktikum sa kodom
(Faculty of Science, University of Kragujevac, 2023-06-01) Ivanović, Miloš
Neuronske mreže podržane fizičkim zakonima (Physics-Informed Neural Networks - PINN) ili na srpskom jeziku NMPFZ su tip univerzalnih funkcija aproksimacije koje mogu da se treniraju tako da usvoje poznavanje bilo kog fizičkog zakona koji se može opisati parcijalnim diferencijalnim jednačinama, a koji važi u određenom prostorno-vremenskom domenu. Obuka ovog tipa neuronskih mreža se postavlja na taj način da poštuje simetrije, invarijantnost ili održavanje principa koji počivaju na fizičkim zakonima iskazanim u obliku parcijalnih diferencijalnih jednačina.Obične duboke neuronske mreže nisu dovoljno robusne u većini slučajeva kada se vezuju za matematički iskazane zakone u biologiji, mehanici, elektrotehnici, itd. S druge strane, kod NMPFZ mreža, prethodno znanje opštih fizičkih zakona se u procesu treniranja neuronskih mreža postavlja kao regularizacioni agent koji ograničava prostor dozvoljenih rešenja, što povećava tačnost aproksimirane funkcije. Na ovaj način, ugrađivanjem fizič kih zakona opisanih parcijalnim diferencijalnim jednačinama u neuronsku mrežu dobijamo poboljšanje, što olakšava algoritmu učenja da dobije što tačnije rešenje i da dobro generalizuje, čak i sa veoma malom količinom tzv. kolokacionih tačaka.
Should I be bothered or not? Development of the Environmental Attitudes Scale (EAS)
(University of Novi Sad, 2022) Hinić, Darko
The aim of this paper was to develop a reliable scale evaluating values, beliefs, and attitudes towards the environment, and to test its basic psychometric properties relative to its employment in Serbia. The final sample included 1020 participants (46.9% male and 53.1% female), aged from 18 to 86 (M = 39.29, SD = 15.77). All the participants completed the demographic questionnaire (age, sex, region, education, work, and economic status), and the EAS scale. This final scale included 34 items grouped into seven dimensions explaining 51.84% of the common variance: Love of nature 18.72%, Population growth policies 10.24%, Pro-environmental behaviours 8.94%, Preservation measures 4.28%, Environmental concern 3.87%, Instrumentalism 3.12%, and Environmental activism with 2.27% of the variance explained. EAS showed internal consistency ranging from .74 to .82 for the factor scales, and test-retest rtt = .80. Results confirmed three second-order factors (84.17% of variance explained): Pro-environmental factor (explaining 46.11% of the variance), contained the Love of nature, Environment concern, Pro-environmental behaviour, Environmental activism, and Preservation measures factors, the second contained only Population growth policies factor, explaining 25.19% of the variance, while the third contained the Instrumentalism factor, explaining 12.87% of the variance.
Genetic determination of technological quality in Triticum durum.
(CODEN PDBIAD, 2008-10-31) Đukić, Nevena; Knežević, Desimir; Zečević, Veselinka
Coulson function and total 𝜋–electron energy
(Faculty of Science, University of Science, 2002) Gutman, Ivan; Furtula, Boris; Vidović, Dušica
It is shown that the value of the variable x, at which the Coulson function F(G,x) has its inflection point, is related to the respective total тг-electron energy (E) and depends mainly on E and the number of non-bonding molecular orbitals.
New records of Serbian “archaic” and endemic earthworm Allolobophora (sensu lato) paratuleskovi (Šapkarev, 1975): geographic range size and biogeographic significance
(2022-06) Popovic, Filip; Stojanovic, Mirjana; Sekulić, Jovana; Trakić, Tanja; Radosavljević, Slobodanka
The present study provides new data on the distribution of endemic species Allolobophora (sensu lato) paratuleskovi (Šapkarev 1975) in the southwestern and southern parts of Serbia. Allolobophora (s.l.) paratuleskovi is an endemic species known to inhabit the Balkan part of Serbia but the knowledge on its distribution is largely based on old literature. Our research indicated that All. (s.l.) paratuleskovi is still present in the southwestern part of Serbia, but taking into account new localities, it is evident an extension of the distribution of this species to the south. Based on the identified localities, the new site Leposavić presents the southernmost limit of the species’ natural range and first finding in Kosovo. Considering the overall distribution of All. (s.l.) paratuleskovi, it is possible to assume that the place of the subduction between Adria and Europe (Vardar zone) is indeed the area of its origin. Our research shows that the major distribution center of this endemic species is located on the southwestern slopes of Kopaonik Mountain. For the first time, based on the extent of occurrence (EOO), it was shown graphically geographic range size of All. (s.l.) paratuleskovi.
Excessive Screen Media Exposure and Language Delay in the Development of Infants and Toddlers – Three Case Reports
(University of Kragujevac, Faculty of Medical Sciences, 2021) Simonović, Senka; Hinić, Darko
Early exposure to digital media has become an integral part of everyday life, which is frequently being reported as one of po-tential risk factors for a number of developmental disorders, in-cluding language development in infants and toddlers. The cur-rent article represents introduction to a research study which will be dealing with a potential link between the risk of language delay and excessive screen media time in children. With this in mind, we will present three case reports involving young children who ex-perienced a language delay, but did not have any health problems diagnosed, nor did they have any of the physical high-risk factors for language and other developmental disorders detected. What these three children have in common is the fact that they were all excessively exposed to digital media during the first two years of life. The existing empirical findings suggest that different forms of digital content may be overstimulating for the developing brain, which is true both for active and background screen viewing. Moreover, screen time may be seen as a distraction from other more developmentally important activities. Keeping parents in-formed about a potential negative influence of prolonged media exposure can prompt parents to make informed decisions about whether and to what extent they will expose their children to dig-ital media in the earliest period of their development.
Synthesis, characterization, and antimicrobial activity of novel 2-ferrocenyl1,3-thiazolidin-4-thiones
(2021) Todosijević A.; Minić Jančić, Aleksandra; Mihailović, Vladimir; Srećković, Nikola
Synthesis of five novel 2-ferrocenyl-1,3-thiazolidin-4-thiones has been achieved in good to excellent yields through the treatment of 2-ferrocenyl-1,3-thiazolidin-4-ones with Lawesson’s reagent. The reaction was performed by refluxing the reactants mixture in toluene overnight. All prepared compounds were characterized by the IR and NMR spectral data. Further, the obtained products were evaluated for their antibacterial and antifungal activity.
First record of the endemic earthworm Allolobophora (sensu lato) strumicae (Šapkarev, 1973) (Clitellata: Lumbricidae) in Serbia, with comments on its ecology and distribution
(2021) Popovic, Filip; Stojanovic, Mirjana; Trakić, Tanja; Sekulić, Jovana
Variability of harvest index and yield components in wheat (Triticum aestivum L.)
(Akademiai Kiado, 2008-05-03) Knezevic, Desimir; Đukić, Nevena; Paunović, Aleksandar; Madic, Milomirka
Coulson function and Hosoya index
(2002) Gutman, Ivan; Vidović, Dušica; Furtula, Boris
Let G be a molecular graph, n the number of its vertices and φ(G,x) its characteristic polynomial. Already in 1940 Coulson expressed the total π-electron energy of conjugated unsaturated molecules in terms of the function F(x)=n−ixφ′(G,ix)/φ(G,ix). Recently, the Coulson function F(x) found applications also in modeling the structure-dependence of physico-chemical properties of alkanes. We now analyze the Coulson function and establish some of its hitherto unnoticed features, in particular its relations with the Hosoya index.
Chemical applications of the Laplacian spectrum. VII. Studies of the Wiener and Kirchhoff indices
(2003) Gutman, Ivan; Vidović, Dušica; Furtula, Boris
On pseudo null and null cartan darboux helices in minkowski 3-space
(2016) Öztürk, Ufuk; Nesovic, Emilija
In this paper, we introduce the notion of pseudo null and null Cartan Darboux helices in Minkowski 3-space. We characterize the Darboux vectors of the pseudo null and the null Cartan curves in terms of the Darboux helices and the rectifying curves. We find an explicit parameter equation of a pseudo null curve of constant precession and prove that there are no null Cartan curves of constant precession. Finally, we give some examples
New records of earthworms (Annelida: Clitellata) from the Kopaonik Mountain, with the first finding of Allolobophora treskavicensis (Mršić, 1991) in Serbia
(2020) Popovic, Filip; Stojanovic, Mirjana; Sekulić, Jovana; Trakić, Tanja; Radosavljević, Slobodanka; Tsekova, Ralitsa
The aim of the study is to present new data on earthworm diversity in the Kopaonik Mountain, which is situated in the central part of southern Serbia and is a part of the Dinaric Range. A list of species including both published data and newly-recorded species of the family Lumbricidae is presented. It comprises 26 species-group taxa of 10 genera. The genera represented by the largest numbers of species are Aporrectodea (5) and Dendrobaena (5), while the genera Bimastos, Eophila, Eiseniella and Octolasion are represented by one species. The published data about two species-group taxa have not been confirmed by the recent studies. With respect to the zoogeographical analysis, the majority of the recorded taxa belong to the group of peregrine species (11). The endemic species are represented by three taxa and belong to the genus Allolobophora. The Balkan endemic Allolobophora treskavicensis (Mršić, 1991), known from a single locality from the Republic of North Macedonia, is a new species for the fauna of Serbia; the recorded new sites from the Kopaonik Mountain represent the northernmost limit of the geographical range of this species.
Evaluacija Skale poremećaja upotrebe interneta (PUI)
(Društvo psihologa Srbije, 2012) Hinić, Darko
Glavni cilj ove studije je evaluacija Skale poremećaja upotrebe Interneta na srpskom uzorku Internet korisnika, kao i provera faktorske strukture skale i njene korelacije sa izdvojenim parametrima upotrebe Interneta. Ukupan uzorak iznosio je 280 ispitanika, podeljenih u kliničku (70) i kontrolnu grupu (210), uzrasta M=26.73, SD=7.830. Kontrolna grupa formirana je slučajnim izborom od ukupnog broja ispitanika (327) koji su dobrovoljno odgovorili na bateriju testova i ispunili ulazne kriterijume. Kliničku grupu činili su subjekti koji su potražili stručnu pomoć zbog simptoma nefunkcionalne upotrebe Interneta u nekoj od institucija ili privatnih psihijatrijskih i psihoterapijskih praksi u Srbiji, a koji su ispunili kriterijume za klasifikaciju Poremećaja upotrebe Interneta. Interna konzistentnost skale iznosi α=.944, a faktorskom analizom izdvojena su tri faktora koji zajedno objašnjavaju 67.23% ukupne varijanse u obe grupe: Nemogućnost kontrole ponašanja i posledice, Preokupacija Internetom i reakcije na deprivaciju, Socijalne posledice poremećaja upotrebe Interneta. Utvrđena je statistički značajna razlika između ukupnih skorova kliničke i kontrolne grupe na revidiranoj skali (t(278)=20.434; p<.000), pri čemu su svi pojedinačni ajtemi pokazali značajne diskriminativne vrednosti sa 89.6% ispitanika pravilno klasifikovanih u odgovarajuće kategorije. Takođe je utvrđena značajna pozitivna korelacija između PUI skora i broja sati provedenih na Internetu (r=.519; p<.001), a analiza nije pokazala korelaciju sa varijablama uzrast i dužina korišćenja Interneta, kao ni značajne razlike po polu, obrazovanju i mestu stanovanja ispitanika iz kliničke grupe. Slična situacija je dobijena i na kontrolnoj grupi osim niske korelacije sa uzrastom (r=- 0.253; p=.001).

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