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1118 items

  • Microstructural and magnetic properties of electrospun hematite/cuprospinel composites

    Mira Ristić, Aleksandar Kremenović, Michael Reissner, Željka Petrović, Svetozar Musić (2020)
    Phase composition, microstructural and magnetic properties of electrospun hematite/cuprospinel composites were investigated. Samples were synthesized starting with 0 to 10 mol% of copper relative to iron. The round shape of reference electrospun fbres was preserved upon their heating up to 600 °C in air, whereas at 700 °C hollow substructure was additionally formed. In these reference samples the presence of hematite phase was detected by XRPD. A small amount (traces) of Fe3O4 /γ-Fe2O3 was also found, due to the ...
    Electrical and Electronic Engineering, Condensed Matter Physics, Atomic and Molecular Physics and Optics, Electronic, Optical and Magnetic Materials

  • Hydrographic and hydrological characterization of the Vodenička and Rosomačka rivers

    Vesna Ristić Vakanjac, Marina Čokorilo Ilić, Dušan Polomčić, Dragoljub Bajić, Jelena Ratković (2017)
    The Visočica River rises in Bulgaria, on the Berovo Mountain. Its course in Bulgaria is 16.7 km long. It enters Serbia near the village of Donji Krivodol. Up to the village of Pakleštica, or the beginning of Lake Zavoj, its right-bank tributaries are the Krivodolštica, the Vodenička, the Rosomačka and the Dojkinačka. There are no left-bank tributaries. Among the tributaries, water levels and discharges are gauged only on the Dojkinačka River. The Vodenička had also been gauged but only ...
    hydrographic characteristics, river discharge, the Vodenička River, the Kamenička River
    ... a n n u a l d is c h a rg e Q ( m 3 /s ) The Visocica at Izatovac The Visocica at V. Ržana The Visocica at Braćevci The Visocica at Pakleštica The Dojkinacka atV. Ržana Figure 6 Monthly discharge distributions at the studied gauging stations Слика 6 Унутаргодишње расподеле протицаја ...
    ... on the Visočica. However, three of them have been decommissioned: at Pakleštica, Visočka Ržana and Izatovac. The only remaining station is at Braćevci. For their own needs, Pirot HPP activated the station at Pakleštica in 1990 and at Visočka Ržana in 2011. Based on available data, the paper presents ...
    ... RHMZ had set up three gauging stations on the Visočica: at Pakleštica (which was in service from 1959 to 1990), at Visočka Ržana (from 1958 to 2005), and at Izatovac (from 1963 to 1992). There was another gauging station on the Vodenička, at Kamenica, which was used to monitor water levels and discharges ...

  • Understanding the effect of synthesis and sintering temperature on the functional properties of barium titanate/cobalt ferrite composites

    Marija Šuljagić, Aleksandar Kremenović, Ivan Petronijević, Adis Džunuzović, Miljana Mirković, Vladimir Pavlović, Ljubica Anđelković (2023)
    To investigate the effect of synthesis procedure and sintering temperature on the functional properties of perovskite/spinel ceramics, BaTiO3/CoFe2O4 composites were prepared by thermal decomposition, coprecipitation, and microemulsion method, and sintered at 1150°C and 1300°C. The phase composition and morphology of as-prepared powders as well as sintered ceramics were thoroughly examined by X-ray powder diffraction (XRPD) and scanning electron microscopy (SEM) coupled with electron dispersive spectroscopy (EDS). The dielectric and ferroelectric measurements were performed in detail. Generally, the ...
    Perovskite/spinel ceramics, Multiferroic, Sintering, Influence of synthesis method

  • Synthesis and characterization of high-pressure and high-temperature sphene (CaTiSiO5)

    Jelena Pantić, Vladimir Urbanovich, Vesna Poharc-Logar, Bojan Jokić, Marija Stojmenović, Aleksandar Kremenović, Branko Matović (2014)
    Sphene (CaTiSiO5), a calcium titanosilicate ceramic has been prepared from a powder mixture of CaCO3, TiO2 and SiO2 using vibro-milling for homogenization and activation of precursors. During the highpressure and high-temperature synthesis (HPS) process at 4 GPa and 1,200 °C, sphene undergoes into phase transition, from room-temperature phase P21/a to high-temperature phase A2/a. Evidence of that structural phase transition is given in this paper using infrared, Raman spectroscopy and X-ray powder diffraction. Rietveld refinement was employed to get the ...
    Sphene, Phase transition, Raman spectroscopy, X-ray diffraction, SEM, IR

  • Mitigating hydrate formation in onshore gas wells: A case study on optimization techniques and prevention

    Milica Ješić, Bojan Martinović, Stefan Stančić, Miroslav Crnogorac, Dušan Danilović (2023)
    Gas wells, particularly those situated onshore, play a vital role in the global energy sector by supplying a significant portion of natural gas. However, operational challenges, notably gas hydrate formation, pose substantial issues, leading to complications such as flowline blockages and unexpected well shutdowns. Gas hydrates, crystalline structures resembling ice, ...
    Gas Well, Gas Hydrate Formation, Well Modeling, Well Performance Optimization, Choke Position Adjustments, Methanol Injection

  • An aproach to Implementation of blended learning in a university setting

    Ivan Obradović, Ranka Stanković, Olivera Kitanović, Jelena Prodanović (2011)
    ... support for all active courses covering seven educational profiles, three at the Mining department and four at the Geology department, with a total of 363 courses at undergraduate studies, 254 at master studies and 135 at doctoral studies. The courses supported by the portal involve a teaching ...
    ... FORWARD: MOODLE AT FMG The introduction of Moodle at FMG represented a leap forward in the blended learning system. In 2009, a number of teachers and teaching assistants started expressing their interest in functionalities that were not supported by the existing FMG CMS, and at the same time ...
    ... process. Finally, depending on the nature of the courses offered at FMG, other software tools are also being used in the learning process, especially within ICT oriented courses. The current state of the blended learning approach at FMG will be illustrated by two courses, one offered to students ...

  • Surface functional groups and degree of carbonization of selected chars from different processes and feedstock

    Marija Ilić, Franz-Hubert Haegel, Aleksandar Lolić, Zoran Nedić, Tomislav Tosti, Ivana Sredović Ignjatović, Andreas Linden, Nicolai D. Jablonowski, Heinrich Hartmann (2022)
    The knowledge ofthe structural and chemical properties of biochars is decisive for their application as technical products. For this reason, methods for the characterization of biochars that are generally applicable and allow quality control are highly desired. Several methods that have shown potential in other studies were used to investigate two activated carbons and seven biochars from different processes and feedstock. The chars were chosen to cover a wide range of chemical composition and structural properties as a hardness ...
    Biougalj, različiti procesi dobijanja, različite sirovine, površinski aktivne grupe, x-ray, FT-IR,XPS
    ... sp? carbon. The band at 1576 cm” for AC2 and the double band at 1568 and 1544 cm”! for ACI are associated with aromatic skeletal vibrations. Both activated carbons show broad bands of overlapping, peaks with a minimum at 1193 cm'! for AC2 and 1084 cm”" for ACL1. The band at 1081 cm"! for AC2 is ...
    ... untreated PW700g, a peak at 873 and another one at 796 cm ! could be associated with CH out-of-plain deformation vibrations. A shoulder and a weak peak at 801 cm ! with lower intensity compared to the large bands of the untreated sample are also observed for the HCI- treated PW700g at this positions. This ...
    ... deformation and C-O stretching vibrations [85]. At the flank oftthese bands at lower wavenumbers, peaks are present for the treated and the untreated sample which however do not completely coincide. A peak at 874 cm”! for the untreated sample and at 873 cm ! is present in both spectra and can be ...

  • Application of Peleg model on mass transfer kinetics during osmotic dehydratation of pear cubes in sucrose solution

    Vesna Pavelkić, Tanja Brdarić, Marija Petrović, Gavrilo Šekularac, Milica Košević, Lato Pezo, Marija Ilić (2015)
    The applicability of Peleg model was investigated for predicting mass transfer kinetics during the osmotic dehydration (OD) process of pears, at different concentrations (40, 60 and 70%, w/w) and temperatures (20, 35 and 50 °C) of sucrose solution. Increase in sucrose solution concentration resulted in higher water loss (WL) and solid gain (SG) values through the osmotic treatment period. After 360 min of osmotic treatment of pears, WL ranged from 23.71 to 31.68% at 20 °C, from 24.80 to ...
    осмотска дехидрација, крушкa, кинетика, температурни ефекат, Пелег модел

  • The Importance of Detailed Groundwater Monitoring for Underground Structure in Karst (Case Study: HPP Pirot, Southeastern Serbia)

    Marina Čokorilo Ilić, Ana Mladenović, Marina Ćuk, Igor Jemcov (2019)
    Geography, Planning and Development,Aquatic Science,Biochemistry,Water Science and Technology
    ... within the tunnel and at the control gate was conducted while the tunnel was out of operation. Water 2019, 11, 603 4 of 10 Summary losses of the fully charged tunnel were monitored at the control gate following the standard procedure [12], by maintaining the water level at the control gate for one ...
    ... groundwater level at PP-3 were detected when the tunnel was offline (out of operation). The summary water losses in the tunnel were reflected in a continuous decrease in the water level in the observation well, as well as at the control gate (Figure 4). The decrease in the groundwater level at PP-3 during ...
    ... and at the control gate (CG) while there were water losses from the tunnel, showing the entire period of monitoring of groundwater level in PP-3 (A) and water temperature at the control gate (B). The high reactivity of observation well PP-3 was apparent while the tunnel was being recharged, at which ...

  • Lower Berriasian ammonites from Dedina (Golubac Mountains, eastern Serbia) and their biostratigraphic implication

    Zdenek Vasícek , Dragoman Rabrenović, Petr Skupien, Barbara Radulović (2023)
    Ammonites, Taxonomy, Lower Berriasian, Getic, Northern Tethys, Serbia
    ... mm. H = 14.5 (0.37), and U = 15.6 (0.39). At D = 36.5 mm (in the elongation axis), H = 12.7 (0.35), and U = 14.8 (0.405). At Dmax, there are 23 ribs at the umbilicus and 42 ribs at the ventral side per half-whorl. Between the main axes of deformation at D = 37 mm, H = 13.5 (0.36), and U = 15.9 ...
    ... tubercles. Measurements. Specimen 96/6, at Dmax = 37.5 mm, has H = 16.0 (0.43) and U = 10.5 (0.28). The 28 ribs at the umbilicus lie at half of the whorl. In spec. 97/4 at D = 27 mm, H = 12.5 (0.46), and U = 6.6 (0.24). There are 17—18 ribs per half-whorl at the umbilicus and 34—36 ribs in the ventral ...
    ... ribs diverge into two at approximately 2/3 oftheir height. In only one case, there is a single rib. Measurements. Specimen S37/3 reaches a Dmax of approximately 48 mm. At D = 46.5 mm, H = 17.5 (0.38), and U = 17.0 (0.36). There are 23 ribs at the umbilicus per half-whorl at Dmax and 40 ribs on ...

  • Insights into dike nucleation and eruption dynamics from high-resolution seismic imaging of magmatic system at the East Pacific Rise

    Milena Marjanović, Suzanne M. Carbotte, Alexandre Stopin, Satish C. Singh, René-Édouard Plessix, Miloš Marjanović, Mladen R. Nedimović, Juan Pablo Canales, Hélène D. Carton, John C. Mutter, Javier Escartín (2023)
    Multidisciplinary

  • Using English Baits to Catch Serbian Multi-Word Terminology

    Cvetana Krstev, Branislava Šandrih, Ranka Stanković (2018)
    In this paper we present the first results in bilingual terminology extraction. The hypothesis of our approach is that if for a source language domain terminology exists as well as a domain aligned corpus for a source and a target language, then it is possible to extract the terminology for a target language. Our approach relies on several resources and tools: aligned domain texts, domain terminology for a source language, a terminology extractor for a target language, and a ...
    aligned texts, word alignment, terminology extraction, electronic dictionaries, morphological inflection
    ... bl io te ka bi bl io te čk ig ra d̄a li br ar y m at er ia l 1 bi bl io te čk og m at er ij al a bi bl io te čk im at er ij al i bi bl io te čk im at er ij al bi bl io te čk ig ra d̄a li br ar y m at er ia l 1, 3, 5, 6 ye s gr ad̄ e iz dr ug ih bi bl io ...
    ... in fo rm a- ci on is is te m li br ar y in fo rm at io n sy s- te m 1, 2, 3, 4 bi bl io te ka m ed ij at ek a bi bl io te ka m ed ij at ek a bi bl io te čk i in fo rm a- ci on is is te m li br ar y in fo rm at io n sy s- te m 1 dr ug im bi bl io te čk o in ...
    ... ar y m at er ia l 1 bi bl io te čk e st an da rd e bi bl io te čk is ta nd ar d bi bl io te čk is ta nd ar d bi bl io te čk ig ra d̄a li br ar y m at er ia l 1, 3, 5, 6 no u pi ta nj u bi bl io te čk im at er ij al pi ta nj e bi bl io te čk im at er ij ...

  • Definition of Circulation Conditions and Groundwater Genesis of the Complex Krupaja Hydrogeological Karst System (Eastern Serbia)

    Ljiljana Vasić, Saša Milanović, Tina Dašić (2023)
    Management, Monitoring, Policy and Law,Renewable Energy, Sustainability and the Environment, Geography, Planning and Development, Building and Construction
    ... with depth. The maximum Mg2+ value at the Krupaja Spring, was 2.875 mg/L, at the borehole 7.205 mg,/L, and at the thermal spring, 13.96 m/L, while the maximum Na*? value ranges from 2.202 mg/L at Krupaja Spring, over 8.986 mg/L at borehole B-1, up to 19.07 mg/L at the Krupaja thermal spring.. The ...
    ... substances with increasing depth and temperature, ranging, from 505 to 526 us/cm at the Krupaja Spring, from 523 to 543 at the borehole, and from 543 to 560 us/cm at the thermal spring.. Dissolved oxygen is the highest at Krupaja Spring, during, the spring period (10.26 mg/L), which is a consequence ...
    ... groundwater formation and the depth of groundwater circulation. The thermal spring is located at a distance of about 50 m from the cold Krupaja Spring; it emerges at an altitude of 215 m above sea level, at the contact point of the Red Permian sandstone overthrust over the Urgonian limestone; it has ...

  • Hydrodynamic analysis of radial collector well ageing at Belgrade well field

    Đorđije Božović, Dušan Polomčić, Dragoljub Bajić, Jelena Ratković (2019)
    The origin and effect of hydraulic resistances on the rate of ageing of radial collector wells are identified through numerical hydrodynamic analysis. The research includes hydrodynamic modeling of one such well with new laterals at Belgrade well field. The performance of the laterals is aggravated by rapid ageing. The change in the hydraulic parameters of the laterals during the first decade of operation is analyzed through simulations of the groundwater regime with realistically specified geometries and hydraulics of the ...
    Colmation, Incrustation, Groundwater modeling, MODFLOW–USG, Connected Linear Network Process

  • Kinetics, mechanism, and equilibrium studies of the reactions between a ruthenium(II) complex and some nitrogen- and sulfur-donor nucleophiles

    Aleksandar M. Mijatović, Ratomir M. Jelić, Jovana Bogojeski, Živadin D. Bugarčić, Biljana Petrović (2013)
    Kinetika i mehanizam reakcija supstitucije između [Ru(trpi)(bpi)Cl]+ sa nukleofilima gvanozin-5′-monofosfatom, L-histidinom, tioureom i dimetilsulfoksidom proučavani su spektrofotometrijski u 0,1 M NaClO4 na 310 K. Red reaktivnosti za odabrane ligande je: tiourea > gvanozin-5′-monofosfat > L-histidin > DMSO. Ovaj red je povezan sa elektronskim, strukturnim i hemijskim karakteristikama kompleksa i nukleofila. Reakcija supstitucije sa tioureom je proučavana na tri različite temperature (288, 298 i 310 K). Negativna entropija aktivacije DS = potvrđuje asocijativni način aktivacije. Formiranje kompleksa [Ru(trpi)(bpi)H2O]2+ sa ligandima ...
    Kinetika, Ravnoteža, Ru(II), L-Histidin, Guanozin-5' -monofosfat, Dimetilsulfoksid, Tiourea
    ... almost at the beginning of the potentiometric titration giving [Ru(trpy)(bpy)(HL)]2? (HL = 50-GMP) complex with the maximum in concentration at a pH of about 5. The complex with deprotoneted nucleotide [Ru(trpy)(bpy)(L)]? starts to form at pH 5, and its maximum in concentration is reached at a pH ...
    ... concen- tration at pH = 4. This ion is assumed to form through the dimerization of [Ru(trpy)(bpy)H2O] 2? and [Ru(trpy)(bpy) (OH)]? complexes via the hydroxo group as shown in Eq. (4). The [Ru(trpy)(bpy)(OH)]? ion begins to form at pH = 2 and reaches the maximum in concentration at pH = 8. The complex ...
    ... in concen- tration at pH = 4. This ion is assumed to form through the dimerization of [Ru(trpy)(bpy)H,O]** and [Ru(trpy)(bpy) (OH)]* complexes via the hydroxo group as shown in Eq. (4). The [Ru(trpy)(bpy)(OH)]* ion begins to form at pH = 2 and reaches the maximum in concentration at pH = 8. The complex ...

  • Redesign, upgrading and unification of the drum at belt conveyors of the main mining equipment at opencast mines

    Ignjatović Dragan, Maneski Taško, Jovančić Predrag, Tanasijević Miloš (2011)

  • FTIR spectroscopic study оf S-мetolachlor сorption оn inorganic and organically modified montmorillonite from Bogovina

    Lazar Kaluđerović, Zorica Tomić, Jelena Bogosavljević, Ljubomir Životić, Maja Milošević (2021)
    ... va(H->O) stretching vibrations, while band at 3223 cm ! represent overtone of bending vibrations (2v)(H.O)) (He et al., 2007). At the spectrum of the HDTMA bromide, in the region from 3050-2800 cm !, several bands occur (Fig. 1b). Shoulder at 3030 cm ! and band at 3018 cm ! represent vs(N-CHx) vibrations ...
    ... 2009), alttough some authors state that this band at 3018 cm ! originate from v.(N-CHx) vibrations (Li et al., 2008). Shoulder at 2945 cm"! originates from overlapping v.(N-CHs) with va(CHhx) vibrations (Madejova et al., 2009). A small band at 2870 cm"! represent symmetric stretching ' vibrations ...
    ... spectrum of PTMA, namely, at 1594, 1500, 1474, 1461, and 1416 cm"!(Fig. 1f). The band at 1300 cm"! was assigned to the vibrations of the ammonium group. Heights of these bands decreased after the interaction between PTMA* cations and montmorillonite (Fig. 1e). The band at 1594 cm"! disappeared, probably ...

  • Flotability of chalcopyrite from the Rudnik deposit

    Đurica Nikšić, Predrag Lazić, Milena Kostović (2021)
    Директно селективно флотирање олова, бакра и цинка у флотацији рудника „Рудник” датира од 1984. године. Технолошка шема омогућава директно издвајање селективних концентрата у три циклуса. У првом циклусу се издваја минерал олова (галенит), док су минерал бакра (халкопирит) и минерал цинка (марматит) депримирани. У другом циклусу се оток концентрације минерала олова кондиционира и припрема за издвајање минерала бакра. Након кондиционирања, у овом циклусу се издваја минерал бакра. У трећем циклусу се оток концентрације минерала бакра кондиционира и припрема за ...
    Директно селективно флотирање, халкопирит, KAX, NaCN

  • BaTiO3/NixZn1−xFe2O4 (x = 0, 0.5, 1) Composites Synthesized by Thermal Decomposition: Magnetic, Dielectric and Ferroelectric Properties

    Marija Šuljagić, Ivan Petronijević, Miljana M. Mirković, Aleksandar Kremenović, Adis Džunuzović, Vladimir B. Pavlović, Aleksandra Kalezić-Glišović, Ljubica Andjelković (2023)
    To investigate the influence of spinel structure and sintering temperature on the functional properties of BaTiO3/NixZn1−xFe2O4 (x = 0, 0.5, 1), NiFe2O4, ZnFe2O4, and Ni0.5Zn0.5Fe2O4 were in situ prepared by thermal decomposition onto BaTiO3 surface from acetylacetonate precursors. As-prepared powders were additionally sintered at 1150 °C and 1300 °C. X-ray powder diffraction (XRPD) and scanning electron microscopy (SEM) coupled with electron dispersive spectroscopy (EDS) were used for the detailed examination of phase composition and morphology. The magnetic, dielectric, and ...
    ferroelectric, dielectric properties, magnetic properties, titanate/ferrite composites, phase composition
    ... Tnorganics 2023, 11, 51 8of19 that the BaTiOy/ NiFe>»Ou sintered at 1300 ?C has a Tc over 600 "C, while the Tc value of its analogue sintered at 1150 "C is about 600 ?C. In the case of BaTiOy/ Nio,sZno,s Fe)pOa sintered at 1300 "C, Tc is significantly lower (=%420 "C). This can be explained by ...
    ... dielectric constant was observed for all samples sintered at 1300 ?"C, indicating, strong, requency dependence, Figure 6a. Generally, the dielectric behaviour of samples sintered at 300 "C is nearly the same in comparison to their analogues sintered at 1150 "C as a conse- quence of decreased inhomogeneity ...
    ... ferrites. The P-E loops for all sintered samples at a fixed frequency of 100 Hz and electrical ield of 10 kV/cm are given in the Supplementary material (Figure S1), while a typical hysteresis curve for sample BaTiOy /NiFe>Ou sintered at 1150 "C at the fields of 20 kV/cm is presented in Figure 11 ...

  • Fuzzy stohastički model izbora sistema otvaranja podzemnog rudnika

    Saša M. Jovanović (2016-05-16)
    Investiciono okruženje skopčano sa rudarskom industrijom je veoma svojstveno kada seuporedi sa okruženjima koje susrećemo u tipičnim proizvodnim industrijama. Neke odkarakterisitka rudarstva, koje su često naznačene kao jedinstvene su: visok intenzitetinvesticija, dugi predproizvodni periodi, visok rizik i neobnovljivost resursa.Investiranje u sistem otvaranja rudnika predstavlja dobar primer ireverzibilneinvesticije. Takva investicija zahteva pažljivu analizu, jer nakon njene realizacije ona sene može nadoknaditi bez značajnog gubitka vrednosti. Očigledno je da izbor sistemaotvaranja podzemnog rudnika pripada strateškom planiranju...
    otkopavanje; otvaranje; mreže i grafovi; fuzzy skupovi; stohastičkiprocesi; indeks konveksnosti; sistemi podrške odlučivanju
    ... well as the employees' publications. - The Repository is available at: www.dr.rgf.bg.ac.rs UNIVERZITET U BEOGRADU RUDARSKO – GEOLOŠKI FAKULTET Saša M. Jovanović FUZZY STOHASTIČKI MODEL IZBORA SISTEMA OTVARANJA PODZEMNOG RUDNIKA Doktorska disertacija ...
    ... mogu postojati između k podetaža, y puteva (sistema otvaranja) i y dodeljenih vrednosti. podetaža 1 podetaža 2 podetaža k sistem 1 sistem 2 sistem y vrednost 1 vrednost 2 vrednost y Slika br. 28 Moguće relacije između podetaža, sistema otvaranja i dodeljenih vrednosti U skladu ...
    ... tri sistema se mogu međusobno kombinovati i u tom slučaju se povećava broj potencijalnih sistema otvaranja. Generalno, postupak izbora sistema otvaranja podzemnog rudnika obuhvata identifikaciju, procenu i izbor između alternativa. Da bi rešili problem izbora najpovoljnijeg sistema otvaranja ...