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332 items

  • Assessments of effects of implementation of strategic plans for development of Belgrade District heating system

    Dejan Ivezić, Marija Živković, Aleksandar Madžarević, Miodrag Grujić (2020)
    The district heating system (DHS) is one of the key elements of the Belgrade energy system. Overview of the current state and basic characteristics of the DHS are presented in this paper. The focus is on the planned development of DHS and on the analyses of effects of realization of measures and projects defined by strategic documents related to DHS which are adopted by city authorities (Development Strategy of DHS and Strategy of Belgrade Development). Two exploratory scenarios were ...
    Daljinsko grejanje, LEAP, Primarni energetski faktor, Uvozna zavisnost, CO2 emisija

  • Petrological and geochemical studies of lignite from the Tamnava West field, Kolubara basin (Serbia)

    Milena Pajić, Reinhard F. Sachsenhofer, Achim Bechtel, Ksenija Stojanović, Vladimir Krstić, Dragana Životić (2021)
    ... precursor OM. Significant aromatisation of triterpenoids during diagenesis with microbial activity is also present 1n Tamnava West lignite implying the changes of water column level resulted in slight variations of redox settings and pH during peat stage. ...

  • Design of a sucker rod pumping system

    Ana Ponoćko (2024)
    For a long time in the history of oil production, sucker rod pumps have been the first and in many cases the only choice when it comes to mechanical extraction methods. Proper selection of each individual element of the system enables optimization, which entails benefits in the form of increased efficiency and reduced costs. The first part of the paper presents the underground and surface equipment of the rod pump and describes the operation of the entire system. The ...
    sucker rod pump, fluid production, mechanical extraction methods,, Prosper, QROD, RODSTAR
    ... compressibility of the fluid mixture inside the cylinder. If the fluid is nearly incompressible, very small volume changes due to the small movement of the plunger cause large pressure changes. In cases where the fluid is more compressible (a mixture of gas and liquid), a change in volume is needed to ...
    ... resistance. The thickness of the applied molten metal layer is about 70 um. The clearance between the cylinder and the plunger is a critical parameter and can vary depending, on the pumping conditions. Given the significant depths at which these pumps are installed, only metal plungers are used ...
    ... intake pressure and the pressure drop across the standing valve assembly (seat, ball, and mechanism). At the top of the cylinder, the plunger changes direction and begins to move towards the standing valve, which reduces the volume in the cylinder between the standing and traveling valves and ...

  • 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
    ... purpose of defining, the genesis and water circulation conditions of the two karst springs and the borehole within the Krupaja system, a multi-parameter research concept was applied. Previous research was focused on creating, a spatial model of the Krupaja Spring, karst channel distribution, i ...
    ... the similarity of the results, thereby confirming that this water belongs to the same karst system. The results were associated with groundwater changes related to increases in the depths of the karst conduits and the mean residence time. In order to determine the age of the groundwater, radioactive ...
    ... content also increases from 13.158 mg//L at the Krupaja Spring, to a maximum of 24.797 mg/L at the thermal spring. This ionic composition, which changes with depth, clearly indicates the contact of this water with another rock mass not containing, carbonates. Sustainabilihy 2023, 15, 11146 11of14 ...

  • Long-term rockslope monitoring and rockfall prediction

    Miloš Marjanović, Biljana Abolmasov, Marko Pejić, Jelka Krušić (2021)

  • Characterization of Natural Clay from Bogovina (Serbia) and Possible Utilization in Sorption of the Herbicides

    Lazar Kaluđerović, Zorica Tomić, Rada Đurović-Pejčev, Maja Milošević (2021)
    ... sorption with increasing the content of the organic complex used in the montmorillonite modification. Positive relationship between the parameter Kf and the content of the organic complex was found. A general trend of sorption can be presented in the following sequence: ...
    ... of natural clay samples was performed using the X-ray diffraction method. This method was also used in order to track structural changes in montmorillonites during the modification treatment and adsorption process.  Based on the X-ray diffraction diagrams, it was concluded that, after ...

  • Strain partitioning around an indenter during oroclinal bending: kinematics of the Circum-Moesian fault system of the Carpatho-Balkanides

    Nemanja Krstekanić, Liviu Matenco, Uroš Stojadinović, Ernst Willingshofer, Marinko Toljić, Daan Tamminga (2021)
    ... associated with significant strain partitioning within tens to hundreds of metres widedeformation zones. Kinematics of the Circum-Moesian fault system changes from transtensionalin the north, where the formation of numerous basins is controlled by the Cerna or Timok faults,to strike-slip and transpression ...

  • A Mathematical Learning Environment Based on Serbian Language Resources

    Radojičić Marija, Obradović Ivan, Stanković Ranka, Utvić Miloć, Kaplar Sebastijan (2018)
    In recent years, in line with ever growing usage of Information technology, the learning environments are changing. The amount of available learning materials in various forms has increased. These new environments demand comprehensive learning systems, which enable management of the learning corpus with special attention paid to relevant lexical resources. In this paper we present the concept of a Mathematical Learning Environment in Serbian (MLES), which is based on a corpus of mathematical materials and various lexical resources, enabling ...
    mathematical content, text processing, mathematical formulae
    ... N Rapid development of information technology, resulting in a growing number and availability of learning materials, had a strong impact on changes in learning environments. New learning environments are needed, requiring appropriate technology to facilitate access to and management of ...
    ... possibility of updating terms either only in Serbian, or only in the English, or simultaneously in both languages. Term modification implies changes of the very properties of the term (name, abbreviation, synonyms and description) as well as modification of external connections of the term ...
    ... has all rights within the application. Finally, it should be noted that as a precaution logical deletion is performed not physical, while all changes are stored in a separate table. Naturally, only the administrator has the right for physical deletion. IT Education and Practice Radojičić ...

  • Life Cycle Assessment of Individual Wood Biomass Heating Systems in Households

    Boban Pavlović, Dejan Ivezić, Marija Živković (2020)
    The use of solid fuels (wood biomass and coal) for heating of households continues to be common practice within European countries. Solid fuel combustion in households contributes more than 46% to total emissions of fine particulate matter. In this study, a life-cycle assessment (LCA) of firewood-based and pellet-based heating systems is performed. These two systems represent two different types of individual wood biomass heating systems. In the case of the firewood-based heating systems, it is analyzed a typical stove ...
    Grejanje, Analiza životnog ciklusa, Drvna biomasa, Individualni sistemi grejanja
    ... 14040 was revised, and a new standard ISO 14044 was presented. Formal changes include the reduced number of standards, the reduced number of annexes, and the reduced number of pages that contain requirements. All these changes are intended to increase the readability and accessibility of the standards ...
    ... HS if the whole life cycle is analyzed. In the production phase of the LC, firewood-based HS has a lower impact on the environment and climate changes. This is directly related to the quantity of materials of which HS was made. Over the use phase, wood pellet-based HS has a lower impact. This is ...

  • Adaptive neuro-fuzzy prediction of operation of the bucket wheel drive based on wear of cutting elements

    Filip Miletić, Predrag D. Jovančić, Milos Milovančević, Dragan Ignjatović (2020)
    The capacity of the rotor excavator depends largely on the operation of the subsystem for digging. There is a great contribution to the correct and sharp teeth when the capacity is the highest. In the function of time, the teeth become clogged due to abrasive wear, or changes in their geometric shape. To analyze the bucket wheel drive in depend on wear of the cutting elements in this study adaptive neuro fuzzy inference system (ANFIS) approach was implemented. ANFIS ...
    Pogon rotornog točka, habanje, rezni elementi, ANFIS

  • Integrated Stratigraphy of the Middle–Upper Jurassic of the Krížna Nappe, Tatra Mountains

    Renata Jach, Nevenka Đerić, Špela Goričan, Daniela Reháková (2014)
    carbon and oxygen isotopes, radiolarians, calcareous dinoflagellates, radiolarites, Krížna Nappe, West ern Carpathians, Tethys
    ... excursions are explained by the reworking and oxidation of organic matter. These isotope events usually coincided w1t.h long-term sea-level changes. In most cases, negative 85C events werc associated with sca-levci fall, positive ones Wwith sea-level rise, whereas long-term declines in 85C ...
    ... have been studied widely, in terms of depositional processes, bio- and chemostratigraphy as well as thcir significance to the record of climate changes (Baumgartner, 2013 and references the- rein). Correlation of regional biostratigraphic schemes often remains ambiguous, because of the mosaic facies ...
    ... the Western Tatra Mountains) and grabens (the Suchy Wierch—-Havran Unit in the High Tatra and Belianske Tatra Mountains) led to distinct facies changes (Guzik, 1959; Jach, 2007). The subsiding basins constantly were filled with Fleckenmergel-type sediments (bioturbated “spotted” limestones and ...

  • Freeze-dried nanocrystal dispersion of novel deuterated pyrazoloquinolinone ligand (DK-I-56-1): Process parameters and lyoprotectant selection through the stability study

    Jelena R. Mitrović, Maja Bjelošević Žiberna, Aleksandar Vukadinović, Daniel E. Knutson, Dishary Sharmin, Aleksandar Kremenović, Pegi Ahlin Grabnar, Odon Planinšek, Dominique Lunter, James M. Cook, Miroslav M. Savić, Snežana D. Savić (2023)
    Recently, nanocrystal dispersions have been considered as a promising formulation strategy to improve the bioavailability of the deuterated pyrazoloquinolinone ligand DK-I-56-1 (7‑methoxy-2-(4‑methoxy-d3-phenyl)-2,5-dihydro-3H-pyrazolo[4,3-c]quinolin-3-one). In the current study, the freeze-drying process (formulation and process parameters) was investigated to improve the storage stability of the previously developed formulation. Different combinations of lyoprotectant (sucrose or trehalose) and bulking agent (mannitol) were varied while formulations were freeze-dried under two conditions (primary drying at -10 or -45 °C). The obtained lyophilizates were characterized in terms ...
    Pharmaceutical Science
    ... also depend on this parameter. In this lyophilization phase, the temperature of the formulation should be kept below the critical formulation temperature (CFT). At this temperature, the internal morphology of the product begins to change, resulting in significant changes in the specific surface ...
    ... facilitate comparison of particle size in different formulations, the redispersibility index was calculated (RDI). This parameter allows a better understanding of the changes in particle size, as it reflects the relative particle size change during the observed period. After lyophilization-1 ...
    ... while the release of bound water during crys- tallization would negatively affect stability (Jena et al.. 2016). However, no macroscopic changes or changes in physical state were observed during the three months of storage, which was confirmed by DSC and XRPD (data not shown). This could be due ...

  • Substitution reactions of some novel sterically hindered monofunctional Pd(II) complexes

    Aleksandar Mijatović, Jovana Bogojeski, Biljana Petrović, Živadin D. Bugarčić (2011)
    Reakcije supstitucije monofunkcionalnih kompleksa [(TLtBu)PdCl]+ i [Pd(tpdm)Cl]+, gde je TLtBu = 2,6-bis[(1,3-di-terc-butilimidazolin-2-imino)metil]piridin i tpdm = terpiridindimetan, sa nukleofilima kao što su: tiourea, I−, Br−, NO2−, piridin i dimetil-sulfoksid (DMSO) proučavani su u 0,1 M vodenom rastvoru NaClO4 u prisustvu 10 mM NaCl. Reakcije su sprovedene na tri različite temperature (288, 298 i 308 K) korišćenjem tehnike zaustavljenog protoka na različitim temperaturama. Reakcije supstitucije su praćene pod uslovima pseudo prvog reda sa velikim viškom nukleofila. Dobijeni rezultati pokazuju da kompleks ...
    Materials Chemistry, Inorganic Chemistry, Physical and Theoretical Chemistry
    ... square-planar complexes [1–6,21,22]. It is well known that relatively small struc- tural modifications in a multidentate ligand can produce significant changes in the reactivity of the complexes [7–9]. There is a high interest among scientists nowadays in the field of the steric and electronic tuning of the ...
    ... square-planar complexes [1-6,21,22]. It is well known that relatively small struc- tural modifications in a multidentate ligand can produce significant changes in the reactivity of the complexes [7-9]. There is a high interest among scientists nowadays in the field of the steric and electronic tuning of the ...
    ... pyridine and DMSO were studied spectrophotometrically by following the change in absorbance at suitable wavelengths as a function of time. Spectral changes were recorded over the range from 200 to 400 nm to establish a suitable wavelength at which kinetic measurements could be performed. Substitution reactions ...

  • FTIR Spectroscopic Study Of S-Metolachlor Sorption On Inorganic And Organically Modified Montmorillonite From Bogovina

    Lazar Kaluđerović, Zorica Tomić, Jelena Bogosavljević, Ljubomir Životić, Maja Milošević (2021)
    ... in HDTMA-montmorillonite. Also, the intensity of these bands decreases significantly with increasing concentration of HDTMA+ cation. All these changes are related to the decreasing of the water content in the interlayer space by increasing the content of HDTMA. The occurrence of the stretching CH2 ...

  • Synthesis and characterization of nanostructured Ca0.9Er0.1MnO3

    Tijana B. Vlašković, Bojana Laban, Maja Milošević, Maria Čebela, Vladimir Dodevski, Milena Rosić (2023)
    ... ratios. Obtained Cao,Ero,,MnOx powder was calcined in a temperature range of 800-1000 *C for 15min. Particle size, lattice parameters, structural changes, and specific surface area were investigated. DTA, X-ray diffraction (XRD), FTIR, and Field emission scanning electron microscopy (SEM) were used ...

  • Утицај обртног магнетног поља на дерацемизацију кристала натријум-хлората

    М. Милојевић, А. Жекић, П. Дабић, Б. Вучетић, Б. Максимовић (2023)
    ... crystals is dominant, while at 600 rpm, D – orientation of crystals is dominant. X-ray structural analysis showed that the size of the lattice parameter of the obtained crystals does not depend on their oricntation and field rotational frequency, but only on its strength [5]. [1] C. Viedma, Phys ...
    ... Belgrade e-mail: andrijana(q)ff.bg.ac.rs Viedma ripening [1], application of ultrasonic waves [2], addition of impurities [3] and temperature changes [4] are some of the methods of deracemization of crystals grown from aqueous solutions. This paper will present the results of the influence of a ...

  • The state and perspective of the natural gas sector in Serbia

    Dejan Ivezić, Marija Živković, Dušan Danilović, Aleksandar Madžarević, Miloš Tanasijević (2016)
    The strategy of long-term energy development of Serbia identifies an increase of share of natural gas in final energy consumption as one of the main aims. Serbia has signed a strategic agreement with the Russian Federation on cooperation in the oil and gas sector, within which the project South Stream pipeline is planned to be realized. In addition, the Republic of Serbia has signed the Treaty that establishes the Energy Community and accepted the obligation to implement the Energy ...
    Consumption, natural gas, scenarios of development

  • In-vitro ispitivanje interakcija dva strukturno slična Rh(III) kompleksa Šifovih baza sa HSA/DNK i molekulski doking

    Aleksandar Mijatović, Ljubica Bacetić, Nikola Pavlović, Dušan Ćoćić, Milan Nikolić, Aleksandar Lolić, Rada Baošić (2021)
    Kompleksi metala sa tetradentatnim Šifovim bazama ispoljavaju različitu biološku aktivnost, što omogućava ciljne sinteze novih biološki aktivnih jedinjenja. Proučavane su interakcije H[Rh(acac2en)Cl2] (1) i H[Rh(phacac2en)Cl2] (2) sa humanim serum albuminom (HSA) i sa DNK, primenom fluorescentne i UV-Vis spektroskopije (298 K, pH 7,4). Dobijene su relativno visoke vrednost dinamičke konstante vezivanja (Ksv) i to 3,88·104 M-1 za (1), 7,02·104 M-1 za (2), što ukazuje na značajno vezivanje za HSA. Izračunate konstante unutrašnjeg vezivanja (Kb) su: 2,87·105 M-1 ...

  • Simple 2D Gravity-density inversion for modeling of the sedimentary basin basement

    Ivana Vasiljević, Snežana Ignjatović, Dragana Đurić, (2019)

  • Prognozna ocena resursa kaolinitskih glina u sedimentnim basenima Srbije

    Vladimir M. Simić (2003)
    Kaolinitske gline predstavljaju jednu od privredno najznačajnijih nemetaličnih mineralnih sirovina u Srbiji. Ležišta tih glina odavno se istražuju i eksploatišu u Aranđelovačkom i Kolubarskom basenu i basenima vlašićkog antiklinorijuma. Osim toga, u većem ili manjem obimu istražene su mnoge lokalnosti, a na nekima od njih vršila se povremena eksploatacija. Dosadašnja istraživanja kaolinitskih glina imala su, međutim, prevashodno uzak istraživački cilj - utvrđivanje rezervi glina određenog ležišta, dok su istraživanja regionalnog karaktera bila malog obima i vezana za delove pojedinih ...
    prognozna ocena, resursi kaolinitskih glina, sedimentni baseni, Srbija, geologija, mineralogija, kvalitet, potencijalnost