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140 items

  • Replica of the “Great Triangle Gold Nugget” Belonging to Belgrade University Collection, Gilded or Not?

    Alena Zdravković, Maja Milošević, Ivana Jelić (2021)
    ... mining engineer M. Melnikoff, conservator of the Mining Institute Museum in St. Petersburg, contains details of its location of finding, the weight of the natural nugget (Archive of the Collection of Rocks and Minerals), but with no information of the number of the replica made, and the type ...

  • 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
    ... November 17, 2022 8/38 PLOS ONE Surface functional groups and degree of carbonization of selected chars "Table 2. Composition of chars in weight per weight %. Chars Xo/ % Xa/ % XN/ % No/ % Xs % ACI 85.4+0.38 0.96+0.03 0.63+0.05 6.9+0.1 0.719+0.01 AC2 77.1+0.53 3.51+0.04 <04 17.8+0.8 <0.01 ...
    ... and H were performed on a Vario EL cube (Elementar Analysensysteme GmbH, Langenselbold, Germany). All chars were dried at 106 "C until constant weight. Oxygen was determined with a LECO TCH600 (LECO, St. Joseph, MI, USA). The ash content was determined in a muffle furnace at 815 + 15 "C. Three samples ...
    ... leachates. A sample of 0.500 g of HCI-treated char was shaken with 25 ml of0.05 mol1! NaOH for 24 h to extract organic components of low molecular weight. The solid was separated from the solution by filtration using 0.45 um nitrocellulose fil- ters. The absorbance at 250 nm (A250) was measured as ...

  • Knowledge and Rule-Based Diacritic Restoration in Serbian

    Cvetana Krstev, Ranka Stanković, Duško Vitas (2018)
    In this paper we present a procedure for the restoration of diacritics in Serbian texts written using the degraded Latin alphabet. The procedure relies on the comprehensive lexical resources for Serbian: the morphological electronic dictionaries, the Corpus of Contemporary Serbian and local grammars. Dictionaries are used to identify possible candidates for the restoration, while the dataobtainedfromSrpKorandlocalgrammarsassistsinmakingadecisionbetween several candidates in cases of ambiguity. The evaluation results reveal that,dependingonthetext,accuracyrangesfrom95.03%to99.36%,whilethe precision (average 98.93%) is always higher than the recall (average 94.94%).
    diacritic restoration, morphological dictionary, corpus, word n-grams, local grammars
    ... ”population aging” was explicitly mentioned only once in the text, and it could obtain a too low frequency-based weight, but with the support of the main topic node ”demographic situation”, its weight is considerably higher; • Calculation of category weights in dependence of concepts included into the rules ...
    ... 271,297 3www.labinform.ru/pub/ruthes/index.htm Proceedings of CLIB 2018 95 4. Specific Features of RuThes Structure The main unit of RuThes is a concept as a unit of thought regardless of words expressing it. A concept has a unique, unambiguous name. Concept names are similar to descriptors in ...
    ... Forming the conceptual index of the document. Conceptual index of a document consist of con- cepts found in the document and their assigned weights. The weight of a concept accounts for the 4(https://www.rbc.ru/economics/17/11/2017/5a0eb1d39a79470f724250b4 Proceedings of CLIB 2018 99 significance of ...

  • Application of the VIKOR Method for Selecting the Purpose of Recultivated Terrain after the End of Coal Mining

    Radmila Gaćina, Sanja Bajić, Bojan Dimitrijević, Tomislav Šubaranović, Čedomir Beljić, Dragoljub Bajić (2024)
    reclamation, coal, sustainable development, multi-criteria decision making, VIKOR method

  • A WebGIS Decision Support System for Management of Abandoned Mines

    Ranka Stanković, Nikola Vulović, Nikola Lilić, Ivan Obradović, Radule Tošović, Milica Pešić-Georgiadis (2016)
    ... the factor, the second is the weight coefficient within the group of factors, and the third the final weight coefficient. The sum of all final weights is equal to one. – − − − − − The consistency index is calculated as: CI = (λ − − 1, where λ Figure 6. The weight coefficients. Graphical illustration ...
    ... mapping is available in [15]. Authorized users can access and modify parameters of decision criteria, which adds more flexibility to the system. 2.4.3. Weight Coefficients Bearing in mind that the influence of individual factors, i.e., criteria is different, relative assessments by pairs of attributes at ...

  • Application of VIКOR method in the selection of an optimal splution of excavation “Borska Reka” ore deposit

    Sanja Bajić, Dragoljub Bajić, Branko Glušćević, Radmila Gaćina (2023)

  • Study of the Synergetic Effect of Co-Pyrolysis of Lignite and High-Density Polyethylene Aiming to Improve Utilization of Low-Rank Coal

    Ivan Kojić, Achim Bechtel, Nikoleta Aleksić, Dragana Životić, Snežana Trifunović, Gordana Gajica, Ksenija Stojanović (2021)
    Polimeri i plastika, opšta hemija
    ... Belgrade, Faculty of Chemistry. Polymers 2021, 13, 759 5 of 25 Figure 1. The characteristic weight loss (thermogravimetric analysis, TGA), differential scanning calorimetry (DSC), and derivative weight loss (DTG) curve of lignite (a), HDPE (b), and the lig- nite/HDPE mixture (c). 2.5. Analysis of ...
    ... 3.1. TGA Analysis Figure 1a shows the TGA curve and derivative weight loss (DTG) curve of pre- extracted lignite. The first peak at 90.8 ◦C corresponds to loss of moisture. Degradation of OM starts at about 300 ◦C and the greatest weight loss is observed in the temperature interval between 400 and 500 ...
    ... peak, followed by weight loss, starts at about 390 ◦C and ends at about 505 ◦C. The presence of one sharp peak in DTG indicates only one degradation step of HDPE conversion. The temperature corresponding to the maximum release of volatile substances is 483.2 ◦C, while the largest weight loss, 35.28%, c ...

  • Application of machine learning for diagnosing the operation of a deep well pump in oil production

    Maja Trikić (2024)
    This paper will thoroughly examine how machine learning can improve the diagnosis of deep well pumps by analyzing the role and function of the pumps, dynamograms, sensor technologies, and diagnostic methods.Our analysis will provide insights into modern techniques and approaches for enhancing the performance and reliability of oil production systems, targeting cost reduction and increased operational efficiency.
    deep well pump, dynamograms, machine learning, diagnostics of operating coditions,Random Forest, XGBoost
    ... The load on the smooth rod includes static loads such as the weight of the sucker rods immersed in the fluid, the weight of the fluid column in the tubing above the downhole pump, pressure load on the tubing and annular space, the weight of the fluid column in the annulus, and frictional forces arising: ...
    ... (horseheads) that includes geometric and kinematic parameters of the horseheads. 3. A database of sucker rod characteristics, including dimensions, weight, and maximum Stresses. 4. A database of basic geometric dimensions of downhole pumps necessary for calculating baseline theoretical dynamograms ...
    ... ( 2+ + Ax). At point D, the piston begins to move downward, and segment DA depicts this movement at a constant load. This load corresponds to the weight of the sucker rods immersed in the fluid, reduced by frictional forces.If tubing anchors are used to reduce expansions due to stretching and c ...

  • Keyword Extraction from Parallel Abstracts of Scientific Publications

    Slobodan Beliga, Olivera Kitanović, Ranka Stanković, Sanda Martinčić-Ipšić (2017)
    ... as the average weight distributed on the links of a single node and is then used in the procedure of keyword candidate ranking and extraction [8,9]. The node in/outselectivity and generalized in/out- selectivity values are calculated from a directed weighted network as the average weight distributed on ...
    ... there are variations, the usual way of representing documents as a graph models words as vertices (nodes) and their relations as edges (links). The weight of the link is pro- portional to the overall co-ccurrence frequencies of the corresponding word pairs within a corpus. We will focus on the network ...

  • Integrative GHG Assessment in Oil and Gas Industry

    Aleksandar Mirković, Marija Živković, Stevan Đenadić, Darja Lubarda, Chinedu Anyanwa (2023)
    Reducing greenhouse gas emissions is one of the main targets of national strategies in European countries. As a main contributor to emissions, the energy sector is recognized as the most promising to apply measures and actions aimed to decrease GHG emissions. The Oil and Gas industry as a significant contributor to global greenhouse gas emissions is facing a growing need for estimating, mitigating, and reducing the impact of their operations on the atmosphere to stay competitive in a newly ...
    energetska tranzicija, gasovi staklene baste, industrija, nafta i gas
    ... using the equation [8]: 1 Wt%OC, — 100 mixture — » ;gn,mnenu (Wt%l· ·Wt%c,·) (8) Where: W/t%; - weight percent of component i; W/t%c;i - carbon content of component i on a weight basis. The CO- emission factor can be calculated by using the following, equation [8]: || Eeo, =FC.| _C———— ...
    ... where: J - any hydrocarbon compound from Equation 6; 12 - molecular wcight of carbon; X - Stoichiometric cocfficient for carbon; Mw - molecular weight of individual compound. t%Cc = -100% () hydrocarbon Use API Compendium recommended No combustion efficiency 98% for production Flare |« ——— ...
    ... various activitics involved in production and processing. It considers the company's cfforts toward reducing flaring: by employing the gas processing unit to utilize the gas that would otherwise bc flared. Therefore, it provides a comprehensivc representation of thc typical activities and emissions ...

  • Overcoming the Low Oral Bioavailability of Deuterated Pyrazoloquinolinone Ligand DK-I-60-3 by Nanonization: A Knowledge-Based Approach

    Jelena R. Mitrović , Branka Divović-Matović, Daniel E. Knutson, Jelena B. Ðoković, Aleksandar Kremenović, Vladimir D. Dobričić, Danijela V. Randjelović, Ivana Pantelić, James M. Cook, Miroslav M. Savić, Snežana D. Savić (2021)
    Poor water solubility of new chemical entities is considered as one of the main obstacles in drug development, as it usually leads to low bioavailability after administration. To overcome these problems, the selection of the appropriate formulation technology needs to be based on the physicochemical properties of the drug and introduced in the early stages of drug research. One example of the new potential drug substance with poor solubility is DK-I-60-3, deuterated pyrazoloquinolinone, designed for the treatment of various neuropsychiatric ...
    pyrazoloquinolinones, nanocrystals, wet media milling, fasted/fed bioavailability
    ... al chemistry and design of psychopharmaco- logical drugs led to the development of drug candidates with increased lipophilicity and high molecular weight. It is estimated that 90% of new chemical entities are poorly soluble, which is recognized as a major obstacle in drug development [1]. Because co ...
    ... Commons _ logical drugs led to the development of drug candidates with increased lipophilicity and Attribution (CC BY) license (https:// high molecular weight. It is estimated that 90% of new chemical entities are poorly soluble, creativecommons.org /licenses/by / which is recognized as a major obstacle in ...
    ... failures in clinical trials due to insufficient or highly variable drug exposures [4]. By evaluating basic information on molecular structure, molecular weight, as well as results from preformulation studies such as solubility in water and oils, melting tempera- ture, crystallinity, and amorphization ability ...

  • Contribution to the geotechnical classification of municipal waste landfills in Serbia

    Dragoslav Rakić, Irena Basarić, Laslo Čaki, Slobodan Ćorić (2018)
    Management, Monitoring, Policy and Law, Nature and Landscape Conservation, Geochemistry and Petrology, Waste Management and Disposal,Geotechnical Engineering and Engineering Geology,Water Science and Technology,Environmental Chemistry,Environmental Engineering

  • Some models for determination of parameters of the soil oscillation law during blasting operations

    Suzana Lutovac, Dragan Medenica, Branko Gluščević, Rade Tokalić, Čedomir Beljić (2018)
    ... of 0.15 m, and a cartridge weight of 0.1 kg. An electric capacitor was used for initiation of the explosive. During experimental investigations performed in the Veliki Krivelj Open Pit, the following blasting parameters were specified: ‚ depth of borehole: 0.5 m; ‚ weight of explosive charge per borehole: ...
    ... properties of the working environment, the following values are obtained: ‚ angle of internal friction: φ = 31˝351 ‚ cohesion: C = 138.33 kPa ‚ volume weight: γ = 26.26 kN/m3 ‚ compressive strength: σp = 80.808 MPa ‚ tensile strength: σz = 7.59 MPa ‚ velocity of longitudinal elastic waves: cp = 6661.00 ...

  • History of meteorite donations to the Collection of Minerals and Rocks of the University of Belgrade, Faculty of Mining and Geology (Serbia)

    Alena Zdravković, Maja Milošević, Kristina Šarić, Ivana Jelić, Ana Černok (2021)
    ... It was confirmed that the samples and labels with French handwriting are truly donated by Marquise de Mauroy (Zdravković, 2014). The samples’ weight written on the labels was also very useful. The numbering of the samples and confirmation of the label names were done in 2014, thanks to the ...

  • Parametri zbijanja komunalnog otpada određeni različitim laboratorijskim metodama

    Jovana M Janković Pantić, Dragoslav R Rakić, Irena G Basarić Ikodinović, Tina D Đurić, Snežana Bogdanović (2021)
    Zbijanje komunalnog otpada predstavlja jednu od osnovnih faza korišćenja komunalne deponije. Zbog toga je kao i kod drugih nasutih građevina, veoma korisno odrediti parametre zbijanja: maksimalnu suvu zapreminsku težinu (dmax) i optimalnu vlažnost (wopt). Dobijeni rezultati mogu da posluže prilikom projektovanja kapaciteta deponije kao i prilikom definisanja obradivosti otpada. U dosadašnjoj praksi najčešći način određivanja parametra zbijanja je standardna metoda (Proktorov opit) koja se koristi u mehanici tla, uz eventualnu redukciju energije zbijanja. Međutim, različiti tretmani komunalnog otpada na ...
    deponija komunalnog otpada, zbijanje, Proktorov opit, malj sa šiljcima
    ... operating, е ог ће landfill. Therefore, as with other embankment structures, it is уегу usefull to determine compaction parameters, maximum dry unit weight (ydmax) and optimal moisture content (Wopt). The obtained results can be изед in designing the capacity ог the landfill as well as when defining ...

  • Comprehensive Profiling of Microbiologically Induced CaCO3 Precipitation by Ureolytic Bacillus Isolates from Alkaline Soils

    Olja Šovljanski, Lato Pezo, Jovana Stanojev, Branimir Bajac, Sabina Kovač, Elvira Tóth, Ivan Ristić, Ana Tomić, Aleksandra Ranitović, Dragoljub Cvetković, Siniša Markov (2021)
    MICP process, kinetic study, calcite, vaterite, MALDI-TOF identification, Bacillus licheniformis, Sporosarcina pasteurii
    ... presence in all samples with FTIR analysis. Weight loss dynamics below 400 ◦C vary to a certain extent probably due to a difference in precipitate microstructure (density and particle size), as well as absorbent water. The second part of the DTA diagram shows rapid weight loss above 600 ◦C, followed by a strong ...
    ... mathematical function whose maximum has been determined by evaluating the scores for all variables, according to Equation (2). Each output variable has its weight (wi) when calculating the function SS: SS = w1 · SR + w2 · pH + w3 · UAG + w4 · UAC + w5 · UBT +w6 · UBC + w7 · UBCA + w8 · MUC + w9 · MEC (2) where: ...
    ... of 10 ◦C/min. Two stages in the thermal analysis may be noticed, below and above 400 ◦C. Below 400 ◦C three peaks are noticeable followed by a minor weight loss. The first one occurring around 115 ◦C is assigned to evaporation of humidity. The other two peaks around 220 and 290 ◦C probably represent the ...

  • A multi-criteria approach for assessing the potential of renewable energy sources for electricity generation: Case Serbia

    Boban Pavlović, Dejan Ivezić, Marija Živković (2021)
    When assessing the potential of renewable energy alternatives for electricity generation, it is necessary to implement a multi-perspective approach that includes economic, technical, environmental, and socio-political criteria. For the evaluation of criteria and alternatives, the Fuzzy Analytical Hierarchy Process (FAHP) method is applied. The obtained weights are formed according to the values of energy indicators and expert judgments. The use of a fuzzy numerical value scale for the assessment of expert judgments and energy indicators provides a more sensitive ...
    Proizvodnja električne energije, Obnovljivi izvori energije, Višekriterijumsko odlučivanje, Srbija
    ... that: d′(Ai) = minV (Si ≥ Sk) (10) for k = 1,2, . . .n; k̸=i. Then the weight vector is given by: W ′(d′(A1), d ′(A2), . . . , d ′(Am)) T (11) where (Ai = 1,2, . . . , n) are n elements. Via normalization, the normalized weight vectors are (Chang, 1996): W (d(A1), d(A2), . . . , d(An)) T (12) 5 ...
    ... experts’ judgments for the criteria (C1–C4). Using Eqs. (3)–(5), the values of the fuzzy synthetic extent (S) for the analyzed criteria are obtained. Weight vectors (W) of criteria (C1 – C4) are obtained by using Eqs. (6)–(12). Table 8 shows the values of the S and the WC, which represents the priority ...
    ... alternative (RESs). Table 13 shows the final rank, which is obtained by summing the priority of each alternative previously multiplied by the corresponding weight vectors (WC) of the criteria. According to the multi-criteria assessment, hydropower (A1) has the highest priority (0.3678). With nearly the same ...

  • Multiple-Criteria Decision-Making in Mine Development Planning

    Sanja Bajić (2023)
    The Borska Reka ore deposit is an experimental location where developed methodologies have been applied. It is the largest ore body within the Bor mining complex, which has been the subject of numerous studies and analyses for more than three decades. The paper focuses on the application of FAHP and the VIKOR method to address ranking of alternatives and select the optimal mining method by means of fuzzy multicriteria optimization.

  • Tectonic evolution of the Vršac Mts. (NE Serbia): Inferences from field kinematic and microstructural investigations

    Uroš Stojadinović, Nemanja Krstekanić, Bojan Kostić, Marija Ružić, Aleksa Luković (2021)
    The Vršac Mts. in NE Serbia represent the key area to investigate structural relations between the Northern Serbo-Macedonian Subunit and Supragetic Unit of the Dacia Mega-Unit. The geodynamic events during the Variscan orogeny in the Late Paleozoic colligated the two units and led to their metamorphic differentiation. The Late Cretaceous extension exhumed the medium-grade Serbo-Macedonian metamorphic rocks and structurally juxtaposed them against the low-grade metamorphosed basement of the Supragetic Unit along an E-dipping shear zone, which outcrops in the ...
    severna srpsko-makedonska subjedinica, supragetikum, kinematska analiza, multifazna ekstenzionalna deformacija
    ... al. 2008; Ustaszewski et al. 2010). Located to the east (in present-day coordinates) of the Serbo- Macedonian Unit, the Supragetic Unit represents the upper- most nappe of the Dacia Mega-Unit nappe system, predomi- nantly comprised of low-grade greenschist facies metamorphic rocks (Fig. 1b, Kräutner ...
    ... Cretaceous closure of the Ceahlău–Severin Ocean and Carpathians continental collision, the Supragetic Unit was thrusted over the Getic Unit, forming the largest of the E-vergent Dacia Mega-Unit nappes (e.g., Krstekanić et al. 2017, 2020). The retreat and steepening of the subducting Neotethys oceanic ...
    ... nian Unit Supragetic nitU Upper Getic sub-unit Ceahlau–Severin nitU Danubian nit/West Balkan U Forebalkan, Kula nitsU Moesian Platform post-Miocene Thrust fault Normal fault Strike-slip fault Tectonic units Magmatics and associated sediments Structures River Lower Getic sub-unit Ophiolitic ...

  • Models of Determining the Parameters of Rock Mass Oscillation Equation with Experimental and Mass Blastings

    Suzana Lutovac, Branko Gluščević, Rade Tokalić, Jelena Majstorović, Čedomir Beljić (2018)
    ... 38/1 kHz Operator: (Vector max (ch 1-3) 3.50 mm/s at 0.068 s Notes: MM-3 Timescale 0.4 s/div Channel 1 Channel Channel Input Geo Input Input Unit mm/s Unit Unit Trig level 4 Trig level Trig level Pk 1.735 Pk Pk Diff m/s2 0.434 Diff m/s2 Diff m/s2 Integ um 9.57 Integ ym Integ um Frq(zx) Hz 39.5 Frq(zx) ...
    ... cartridge length 0.15 m, and cartridge weight 0.1 kg. Electric capacitor was used for initiation of the explosive [17]. During experimental investigations performed in Majdanpek open pit, the following blasting parameters were specified: • depth of borehole: 0.5 m, • weight of explosive charge per borehole: ...
    ... of physical and mechanical properties of the working environment, submitted the following results: • Compressive strength 21.1–93.0 MPa • Volume weight 17.1–26.3 kN/m3 • Density 0.97–0.99 kN/m3 • Porosity 0.0004%–0.026% • Water suction 0.08%–0.23% 4.2.2. Blasting Method Measurements of seismic ...