Претрага
950 items
-
Double traveling valve increases rod-pump efficiency
Traditional sucker rod pumps (SRP) use a single traveling valve, but recent double traveling valve innovations have improved SRP performance and efficiency in field applications with double traveling valves installed in pumps with top mechanical seating. The valves sealed better and produced similar fluid volumes compared with the previous single-valve pumps. They also enabled a reduction in pump diameter and optimized usage of surface equipment. Overall, the double travel valve SRPs produced stable production rates and annual production targets.Miloš Petrović, Bojan Martinović, Milica Ješić, Miroslav Crnogorac. "Double traveling valve increases rod-pump efficiency" in Oil & Gas Journal (2023)
-
A comparison between ARIMA, LSTM, ARIMA-LSTM and SSA for cross-border rail freight traffic forecasting: the case of Alpine-Western Balkan Rail Freight Corridor
Miloš Milenković, Miloš Gligorić, Nebojša Bojović, Zoran Gligorić. "A comparison between ARIMA, LSTM, ARIMA-LSTM and SSA for cross-border rail freight traffic forecasting: the case of Alpine-Western Balkan Rail Freight Corridor" in Transportation Planning and Technology, Informa UK Limited (2023). https://doi.org/10.1080/03081060.2023.2245389
-
Polyhedral characteristics of the cosalite-type crystal structures
Sabina Kovač, Predrag Dabić, Aleksandar Kremenović, Aleksandar Pačevski, Ljiljana Karanović, Marko V. Rodić, Martina Tribus (2019)Sabina Kovač, Predrag Dabić, Aleksandar Kremenović, Aleksandar Pačevski, Ljiljana Karanović, Marko V. Rodić, Martina Tribus. "Polyhedral characteristics of the cosalite-type crystal structures" in The Canadian Mineralogist, Mineralogical Association of Canada (2019). https://doi.org/10.3749/canmin.1900017
-
Split-Desktop software for the analysis of fragment size distribution of blasted rock mass
Milanka Negovanović, Lazar Kričak, Stefan Milanović, Jovan Marković, Nikola Simić, Snežana Ignjatović (2023)Drobljenje stena je najvažniji pokazatelj u proceni efekata miniranja pri proizvodnom miniranju u površinskoj eksploataciji. Stepen drobljenja stena ima veliki uticaj na efikasnost daljih operacija utovara, transporta, drobljenja i mlevenja. Optimalno drobljenje stena pri proizvodnom miniranju utiče na smanjenje ukupnih troškova proizvodnje. Stoga je pouzdana procena veličine drobljenja odminirane stenske mase veoma važno pitanje, ne samo u operacijama miniranja, već i u rudarskoj proizvodnji. Za predviđanje distribucije veličine komada odminirane stenske mase postoje različiti empirijski modeli. KUZ-RAM model omogućava ...Milanka Negovanović, Lazar Kričak, Stefan Milanović, Jovan Marković, Nikola Simić, Snežana Ignjatović. "Split-Desktop software for the analysis of fragment size distribution of blasted rock mass" in 9th International Conference Mining and environmental protection, Sokobanja, Serbia, 24 – 27. May 2023, Belgrade : University of Belgrade, Faculty of Mining and Geology (2023)
-
Age of the Jurassic hemipelagic sediments from the Ljubiš area (Zlatibor Mt., SW Serbia)
Nikita Bragin, Nevenka Đerić (2020)... Fig. 4. The section begins with a twometre thick unit consisting of calcareous mass transport deposits and turbidites intercalated with darkgrey radiolarites (GAWLICK et al., 2017) (Unit 1). Five metres of dark greenish- grey thinbedded radiolarites intercalated with greenishgrey cherty claystone ...
... thin-bedded ra diolarites intercalated with greenishgrey cherty mudstone. Thin calcarenite beds appear 3 m above the base of this unit. The whole unit (Unit 4) is 8 m thick. Unit 5 comprises 1 m of a grey massive calcarenite (Fig. 5C). The section ends with 12 m of dark green ishgrey thinbedded ...
... 15-10-11 were taken from the sixth unit (made up of dark greenish-grey thin-bedded radiolarites, with interlayers of greenish-grey cherty mudstones). Sample 15-10-10 yields several radiolarian species with con current stratigraphic ranges that allow us to date them. The most important feature of ...Nikita Bragin, Nevenka Đerić. "Age of the Jurassic hemipelagic sediments from the Ljubiš area (Zlatibor Mt., SW Serbia)" in Geologia Croatica, Croatian Geological Survey (2020). https://doi.org/10.4154/gc.2020.11
-
Development of the Availability Concept by Using Fuzzy Theory with AHP Correction, a Case Study: Bulldozers in the Open-Pit Lignite Mine
Stevan Đenadić, Dragan Ignjatović, Miloš Tanasijević, Uglješa Bugarić, Ivan Janković, Tomislav Šubaranović (2019)Availability is one of the most used terms in maintainability engineering. This concept is used to denote: The quality of service of an engineering system, i.e., machines, weak points’ analysis, asset management, as well as making decisions in the process of life cycle management. Availability is an overall indicator and contains partial indicators that are oriented towards reliability, maintenance, and logistical support. Availability presents a variable value and changes in time and space. Usually, availability is shown as the ...... that according to indicator R machine B1-N was evaluated: • with ‘A‘, three out of four analysts (experts): ((1·0.7)+(1·0.6)+(1·0.5)) 4 = 0.450 • with ‘B‘, all four analysts (experts): ((1·0.3)+(1·0.4)+(1·0.9)+(1·0.5)) 4 = 0.525 • with ‘C‘, only one analyst (expert): (1·0.1) 4 = 0.025 In this way ...
... Equation (15) can be interpreted as follows: Machine B1-N was mostly assessed with good availability at a level of 29%, with a tendency towards excellent availability where the rating level is 23%. Lower grades are represented with 17% for good, 15% for satisfactory and poor availability. If the input grades ...
... subjectivity and mutual over-lapping. Fuzzy logic is used as a mathematical and conceptual model y expert systems with hybrid data. Unlike the classic crisp logic, fuzzy values are defined with membership function to proper linguistic variables [3]. The max–min composition was used, where the outcomes ...Stevan Đenadić, Dragan Ignjatović, Miloš Tanasijević, Uglješa Bugarić, Ivan Janković, Tomislav Šubaranović. "Development of the Availability Concept by Using Fuzzy Theory with AHP Correction, a Case Study: Bulldozers in the Open-Pit Lignite Mine" in Energies, MDPI AG (2019). https://doi.org/10.3390/en12214044
-
Regional rockfall exposure assessment, experience from Serbia
Rockfalls are common in hilly and mountainous areas, especially along roads with engineered slopes and cuts. Such is the case for most of the state and local road routes in Central, Serbia, which was the subject in this case study. A road network of 276 km covering roughly 1700 km2 between the cities of Kraljevo, Čačak and Ivanjica is presented. Assessing of such wide areas needs to be conducted from large to site-specific scale, i.e., using GIS spatial tools ...Miloš Marjanović, Biljana Abolmasov, Uroš Đurić, Jelka Krušić, Snežana Bogdanović. "Regional rockfall exposure assessment, experience from Serbia" in 5th Regional symposium on landslides in Adriatic–Balkan Region, 23-26 March 2022, Faculty of Civil Engineering, University of Rijeka and Faculty of Mining, Geology and Petroleum Engineering, University of Zagreb (2022)
-
Ocena preostalih radnih mogućnosti rotornog bagera metodom primenjene ekspertske ocene sa empirijskim faktorom korekcije - Remaining operational capabilities evaluation of bucket wheel excavator by application of expert assessment method with empirical co
Polovina Dragan, Ivković Slobodan, Ignjatović Dragan, Tanasijević Miloš. "Ocena preostalih radnih mogućnosti rotornog bagera metodom primenjene ekspertske ocene sa empirijskim faktorom korekcije - Remaining operational capabilities evaluation of bucket wheel excavator by application of expert assessment method with empirical co" in Integritet i vek konstrukcija - Structural Integrity and Life 10 no. 1, Beograd:Društvo za integritet i vek konstrukcija i Institut IMS - Society for Structural Integrity and Life & IMS Institute (2010): 31-41. https://doi.org/620.169.1:621.879.48
-
Neogene to Quaternary basalts of the Jabal Eghei (Nuqay) area (south Libya): Two distinct volcanic events or continuous volcanism with gradual shift in magma composition?
Radivojević Maša, Toljić Marinko, Turki Salah, Bojić Zoran, Šarić Kristina, Cvetković Vladica (2015)Radivojević Maša, Toljić Marinko, Turki Salah, Bojić Zoran, Šarić Kristina, Cvetković Vladica. "Neogene to Quaternary basalts of the Jabal Eghei (Nuqay) area (south Libya): Two distinct volcanic events or continuous volcanism with gradual shift in magma composition?" in Journal of Volcanology and Geothermal Research 293, Amsterdam:Elsevier (2015): 57-74. https://doi.org/10.1016/j.jvolgeores.2015.02.0
-
An Underground Mine Ore Pass System Optimization via Fuzzy 0–1 Linear Programming with Novel Torricelli–Simpson Ranking Function
rudna sipka, optimizacija, fazi linearno programiranje, trouglasti graf, Toričelijeva tačka, funkcija rangiranjaDževdet Halilović, Miloš Gligorić, Zoran Gligorić, Dragan Pamučar. "An Underground Mine Ore Pass System Optimization via Fuzzy 0–1 Linear Programming with Novel Torricelli–Simpson Ranking Function" in Mathematics (2023). https://doi.org/10.3390/math11132914
-
Old or New, We Repair, Adjust and Alter (Texts)
Cvetana Krstev, Ranka Stanković (2020)U ovom radu predstavljamo kako se e-rečnici i kaskade transduktora konačnih stanja implementirani u alatu Unitex mogu koristiti za rešavanje tri problema transformacije teksta: ispravljanje tekstova nakon OCR-a, vraćanje dijakritičkih znakova i prebacivanje između različitih jezičkih varijanti.ispravka teksta, OCR greške, restauracija dijakritika , jezičke varijante, elektronski rečnik, transduktori konačnih stanja... *_*срлски ***срдски... Table 1. All candidates are separated with an underscore and delimited with asterisks. The valid replacements in a corrected text are surrounded with plus signs, words that could not be corrected are marked with asterisks. The incorrect letters are given in red, the accepted ...
... American English utterances for British listeners. The system includes spelling and lexicon normalization; the first is being solved with a set of rules, the second with a list of equiv- alences. Similar problems are sometimes tackled as translation problems, as for instance in the case of Arabic dialects ...
... the bottom in Table 2) works for the case when two letters should be replaced with one or more letters. The upper path in this FST works like this: the beginning of the word that needs to be corrected (words preceded with *_*) is assigned to variable $1$, while the last two letters are assigned to variable ...Cvetana Krstev, Ranka Stanković. "Old or New, We Repair, Adjust and Alter (Texts)" in Infotheca, Faculty of Philology, University of Belgrade (2020). https://doi.org/10.18485/infotheca.2019.19.2.3
-
The optimization of auxiliary machinery in open-cast lignite mines: a case study of bulldozers
One of the most important prerequisites for the successful operation of the open-cast lignite mine is to carry out all the auxiliary works timely with the necessary quality. The most important and most commonly used auxiliary machines are bulldozers. Engaging time of bulldozers use is in direct relation with the coefficients of the time and capacity utilization of the continuous system for the excavation of coal and tailings, which indicates their importance. More than 100 bulldozers have been hired ...... ореп-сазг lignite mine is 10 carry out all the auxiliary works fimely with the necessary quality. Тће most important апа most соттоту used auxiliary machines are bulldozers. Engaging time of bulldozers use is in direct relation with the coefficients of the time and capacity ш таноп ој the continuous ...
... other hand, insufficient number of machines (dozers) will result in reduced execution of auxiliary operations, with influence on efficiency of continuous systems. Below is an example with CAT DSR and Shangai PD320Y-1. Optimal replacement те is established, based оп diagrams ог availability of these ...
... concept; Main project – designing; Manufacturing: Application / operation and Decommissioning. As shown in Figure 2, operation of the machine with the highest profit is just a short interval within the operational life. In this period profit is the highest due to low maintenance costs. Subsequent ...Dragan Ignjatović, Predrag Jovančić, Stevan Đenadić, Ivan Janković, Ivica Ristović. "The optimization of auxiliary machinery in open-cast lignite mines: a case study of bulldozers" in 7th International Symposium Mining and Environmental Protection, University of Belgrade, Faculty of Mining and Geology, Belgrade, Serbia (2019)
-
Utilizing sewage wastewater heat in district heating systems in Serbia: effects on sustainability
Marija Živković, Dejan Ivezić (2021)Transformation of the heating sector is recognized as being essential for ensuring reliable and afordable energy services provided with reduced consumption of energy sources and diminished impact on the environment and less import dependency. The possibility of utilizing energy sources that otherwise would be wasted needs to be considered and treated as a big advantage of district heating systems. Despite many advantages, sewage wastewater heat is still a mostly unused resource at the global level and a totally unused ...рекуперација топлоте из отпадних вода, систем даљинског грејања, топлотне пумпе, енергетске уштеде, емисија угљендиоксида, енергетска безбедност, Србија... to provide a current state overview of existing district heating systems, supported with values of selected key performance indicators for the reference year, which will serve as reference values to be compared with. Utilizing sewage wastewater heat in district heating systems in Serbia: effects ...
... tial of this energy source in the cities without WWTP (but with plans for WWTP construction in the future), the heat energy that could be produced from the WWTP and related primary energy savings is calculated for the selected city with WWTP in operation. The obtained energy amounts are set in relation ...
... the total heated area was 42.34 million m2, with a share of households of 81% (Association of Serbian district heating companies 2018). Approximately 20% of the total number of households in Serbia and 43.8% of households in cities are supplied with heat from district heating systems (Association ...Marija Živković, Dejan Ivezić. "Utilizing sewage wastewater heat in district heating systems in Serbia: effects on sustainability" in Clean Technologies and Environmental Policy, Springer Science and Business Media LLC (2021). https://doi.org/10.1007/s10098-021-02063-6
-
Molecular and Isotope Composition of Biomarkers in Immature Oil Shale and its Liquid Pyrolysis Products (Open and Closed System)
Gordana Gajica, Aleksandra Šajnovic, Jan Schwarzbauer, Aleksandar Kostić, Branimir Jovančićević, Ksenija Stojanović (2021)The molecular and isotopic composition of biomarkers in initial bitumen isolated from raw immature oil shale samples from the Lower Miocene Aleksinac Basin (Serbia) and liquid products (LPs) obtained by pyrolysis in open (OS) and closed systems (CS) are studied. The influence of pyrolysis type and variations of kerogen type on biomarkers composition and their isotopic signatures in LPs is determined. The molecular composition of the LPs from the OS pyrolysis is very similar to those in initial bitumen, independently ...... detected in LPs from the CS, showing notably decreasing trend with increase of number of C-atoms. In initial bitumen of raw samples, the distributions of steranes show domination of regular C27–C29 steranes with ααα(R) configuration. Steranes with βαα(R)-configuration, typical for immature diagenetic OM ...
... particularly occur in the CS pyrolysis, it also depends on the kerogen precursor material. The prevalence of lower homologues in LPs is consistent with the predominantly algal origin of organic matter (OM) (Gajica et al., 2017). The n-alkane distributions in all LPs are characterized by uniform ...
... 30th International Meeting on Organic Geochemistry (IMOG) 12–17 September 2021, Montpellier, France LPs from the OS are almost the same with those in bitumen extracts of raw samples. On the other hand, LPs from the CS displayed notably more mature sterane and hopane distributions, which ...Gordana Gajica, Aleksandra Šajnovic, Jan Schwarzbauer, Aleksandar Kostić, Branimir Jovančićević, Ksenija Stojanović. "Molecular and Isotope Composition of Biomarkers in Immature Oil Shale and its Liquid Pyrolysis Products (Open and Closed System)" in 30th International Meeting on Organic Geochemistry (IMOG 2021), European Association of Geoscientists & Engineers (2021). https://doi.org/10.3997/2214-4609.202134040
-
BEYOND 2020 - Geology explorations and open pit activities affectation in reclamation designing in Kolubara Coal Mines (KCM) Serbia, new considerations
Geology explorations in KCM runs from 1936. year up to these days and still ongoing. Results in >7,200 drill holes with ≈600,000 m of core drilling and gave lignite ore resources of > 4,1Bt, which 1,15Bt are excavated since 1986. of XIX up to early years of XXI century. For further mining operations in open pits stay 1,5Bt of lignite. Under waste heaps are ≈80 km2, additional 85 km2 should be filled. All of that masses/areas were, are ...Bojan Dimitrijević, Bogoljub Vučković, Radmila Gaćina. "BEYOND 2020 - Geology explorations and open pit activities affectation in reclamation designing in Kolubara Coal Mines (KCM) Serbia, new considerations" in 17th International Conference of the open and underwater mining of minerals, Sts. Constantine and Helena Resort, Varna, 18-22 September, Bulgaria, Sofia, Bulgaria : Scientific and Technical Union of Mining, Geology and Metallurgy, (2023)
-
Thermal evolution of cation distribution/crystallite size and their correlation with the magnetic state of Yb-substituted zinc ferrite nanoparticles
Vučinić-Vasić Milica, Bozin Emil S., Bessais Lotfi, Stojanović Goran, Kozmidis-Luburić Uranija, Abeykoon Milinda, Jancar Bostjan, Meden Anton, Kremenović Aleksandar, Antić Bratislav (2013)Vučinić-Vasić Milica, Bozin Emil S., Bessais Lotfi, Stojanović Goran, Kozmidis-Luburić Uranija, Abeykoon Milinda, Jancar Bostjan, Meden Anton, Kremenović Aleksandar, Antić Bratislav. "Thermal evolution of cation distribution/crystallite size and their correlation with the magnetic state of Yb-substituted zinc ferrite nanoparticles" in Journal of Physical Chemistry C 23 no. 117, 1155 16TH ST, NW, WASHINGTON, DC 20036 USA:American Chemical Society (2013): 12358-12365. https://doi.org/10.1021/jp403459t
-
Optimal dynamic management of exploitation life of the mining machinery: models with limited interval
Vujić Slobodan, Miljanović Igor, Boševski Stefko, Kasaš Karolj, Milutinović Aleksandar, Gojković Nebojša, Josipović Pejović Milena, Dimitrijević Bojan, Gajić Grozdana, Čebašek Vladimir (2010)Vujić Slobodan, Miljanović Igor, Boševski Stefko, Kasaš Karolj, Milutinović Aleksandar, Gojković Nebojša, Josipović Pejović Milena, Dimitrijević Bojan, Gajić Grozdana, Čebašek Vladimir. "Optimal dynamic management of exploitation life of the mining machinery: models with limited interval" in Journal of Mining Science 46 no. 5, Germany/USA:Springer (2010): 554-560
-
Model of room and pillar production planning in small scale underground mines with metal price and operating cost uncertainty
Gligorić Zoran, Gligorić Miloš, Dimitrijević Bojan, Grozdanović Ines, Milutinović Aleksandar, Ganić Aleksandar, Gojković Zoran (2018)Gligorić Zoran, Gligorić Miloš, Dimitrijević Bojan, Grozdanović Ines, Milutinović Aleksandar, Ganić Aleksandar, Gojković Zoran. "Model of room and pillar production planning in small scale underground mines with metal price and operating cost uncertainty" in Resources Policy, The International Journal of Minerals Policy and Economics, Amsterdam, Holandija:Elsevier (2018)
-
Towards Sustainable Management of Transboundary Hungarian-Serbian Aquifer
Zoran Stevanović, Peter Kozák, Milojko Lazić, Janos Szanyi, Dušan Polomčić, Balazs Kovács, Jozsef Török, Saša Milanović, Bojan Hajdin, Petar Papić (2011)... area and cover the older sediments. Their thickness varies from a dozen to 200m. In the vertical section, water-bearing layers with intergranular porosity interfinger with impermeable strata. Sandy-gravel sediments represent major aquifer systems. Their thickness varies from less than 10 m up to 50 ...
... exlent; . introduce complex water treatment, particuiarly where problems with organic components or increased concentration of Fe, Mn, As is recognized; . delineate the sanitary protection zones of water sources in accordance with criteria, taking into consideration primarily the local hydrogeoiogical ...
... been many activities aiming to improve water management amongst neighbouring countries [1, 2]. Many such projects have been initiated worldwide but, with the exception ofthe European Union (EU) territory, only very few have been successfully implemented or even started. The project Sustainable Development ...Zoran Stevanović, Peter Kozák, Milojko Lazić, Janos Szanyi, Dušan Polomčić, Balazs Kovács, Jozsef Török, Saša Milanović, Bojan Hajdin, Petar Papić. "Towards Sustainable Management of Transboundary Hungarian-Serbian Aquifer" in Transboundary Water Resources Management - A Multidisciplinary Approach, Weinheim, Germany : Wiley-VCH (2011): 143-149
-
Karst aquifer impact on the formation of surface runoff: case study of the Resava River catchment, Serbia
Marina Mitrašinović, Vesna Ristić Vakanjac, Veljko Marinović, Saša Milanović, Ljiljana Vasić, Dušan Polomčić (2022)The paper compares the flow regimes of the Resava River at the gauging stations of the Manasija Monastery (upper course) and the town of Svilajnac (lower course). The hydrological analysis encompasses a multiyear period of monitoring (1982–2020). The water budget and baseflow index are assessed for the catchment areas monitored by the Svilajnac station (683 km2) and the Manasija Monastery station (358k m2), considering the overall monitoring period and characteristic years. The results indicate that the specific runoff in ...... of Mt. Beljanica, in the central part of the study area. It is associated with red Permian sand- stones and dacites of the Krepoljin-Senj zone. Fa- vorable filtration features are attributable to direct tectonic contacts with limestones. 3. Karst aquifer in the castern, upper part of the catchment ...
... Monastery and Qav = 4.65 m?*/s at Svilajnac (Figs. 1a, 1b); • The ycar 1994 with a typical low discharge: Qav = 0.58 m*/s (at the Mansija Monastery) and 0.33 m?*/s (at Svilajnac) (Fig. 1c); and • The year 1999 with the highest discharge: an- nual average 14.64 m?/s at the Manasija Mon- astery ...
... of characteristic years: (q) and (b) years in which the mean annual discharge was equal to the multiycar average, (c) year with a typical low discharge, and (d) year with the highest discharge 256 equal to the multiyear average, to 0.965 in the dry year. The hydrographs show that the ratio ...Marina Mitrašinović, Vesna Ristić Vakanjac, Veljko Marinović, Saša Milanović, Ljiljana Vasić, Dušan Polomčić. "Karst aquifer impact on the formation of surface runoff: case study of the Resava River catchment, Serbia" in National Conference with International Participation “GEOSCIENCES 2022”, Sofia : Bulgarian geological society (2022)