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Упит dcterms_subject_txt:Matematički modeli

808 items

  • Applying the Fuzzy Inference Model in Maintenance Centered to Safety: Case Study – Bucket Wheel Excavator

    Predrag Jovančić, Miloš Tanasijević, Vladimir Milisavljević, Aleksandar Cvjetić, Dejan Ivezić, Uglješa Bugarić (2020)

  • Development of the hybrid MCDM model for evaluating and selecting bucket wheel excavators for the modernization process

    Snezana Savkovic, Predrag Jovancic, Stevan Djenadic, Milos Tanasijevic, Filip Miletic (2022)
    This paper presents a methodology for evaluating and ranking different bucket wheel excavators (BWE) for determining which machine should enter in the process of revitalization and modernization. Various multicriteria methods are used. Combining them achieves the best effect when choosing BVE for the modernization process. AHP, TOPSIS, VIKOR, and PROMETHEE methods are used. The hybrid models are developed from the multi-criteria decision making (MCDM) methods and they are used to evaluate the basic indicators that characterize the operation of ...
    višekriterijumsko odlučivanje, rotorni bageri, modernizacija, ekspertska analiza

  • Model of the Geomagnetic reference field of the Republic of Serbia

    Spomenko J. Mihajlović, Vesna Cvetkov (2024)

  • 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 model stores al] training examples and compares new data to them. It does not create an explicit model but uses examples to make decisions. For example, K-Nearest Neighbors (KNN). 8. Model-Based Learning - The model builds a generalized model based on the training data. This model is used ...
    ... assess model performance and prevent overfitting. 27 c.Evaluation- Measures accuracy and methodology. Assess the model's accuracy in predicting the correct pump states. Analyze errors and misclassifications to further improve the model. • Model Application a. Prediction - The model is used ...
    ... and F1-score are used. b.Cross-Validation- A technique for assessing how the model will perform on unseen data, helping to evaluate the model's stability and robustness. • Model Application a.Prediction - The model is used to predict the pump's condition in real-time based on current sensor ...

  • Regional Slope Stability Analysis in Landslide Hazard Assessment Context, North Macedonia Example

    Miloš Marjanović, Biljana Abolmasov, Igor Peshevski, James Reeves, Irena Georgievska (2020)

  • A Model for Determining the Dependability of Continuous Subsystems in Coal Mines Using the Fuzzy Logic Approach

    Nikola Stanić, Miljan Gomilanović, Petar Marković, Daniel Krzanović, Aleksandar Doderović, Saša Stepanović (2024)
    This study presents a unique model for assessing the dependability of continuous parts of combined systems in open-pit mining through the application of fuzzy logic. Continuous sub-systems as part of the combined system of coal exploitation in surface mines have the basic function of ensuring safe operation, high capacity with high reliability, and low costs. These subsystems are usually part of the thermal power plant’s coal supply system and ensure stable fuel supply. The model integrates various independent partial ...
    fuzzy logic, max-min composition, continuous part of combined system (CCS), open pit, mining, dependability

  • Osnaživanje energetske tranzicije u sektoru domaćinstva u Srbiji: integrativni pristup

    Boban Pavlović (2023)
    Glavni cilj istraživanja bio je da se razvije metodološki pristup koji bi podržao proces energetskog planiranja tranzicije u grejanju domaćinstava, uzimajući u obzir specifičnosti ovog sektora. Kako bi se procenili mogući tokovi energetske tranzicije u grejanju domaćinstava i analizirali politički instrumenti za ubrzanje ovog procesa, razvijen je simulacioni model zasnovan na agentima (Agent Based Model – ABM). Simulacioni model je primenjen na slučaju energetske tranzicije u sektoru domaćinstva u Srbiji. Prethodno su kroz istraživanje prikupljeni podaci o grejanju domaćinstava ...
    energetska tranzicija, energetsko planiranje, energetsko modeliranje, obnovljivi izvori energije, domaćinstva, ponašanje potrošača

  • Analysis of a simplified model for determining rock mass oscillation velocity at the Kovilovača open pit

    Suzana Lutovac, Miloš Gligorić, Jelena Majstorović, Luka Crnogorac (2023)
    ... the values obtained by experimental measurements [6]. Model 1 – Determining the parameters by applying the least square method. The Least Square Method is mainly used to obtain the parameters K and n which represents a common model. Model 2 — Determining the parameters through the application ...
    ... of a simplified model for determining rock mass oscillation velocity at the Kovilovača open pit Suzana Lutovac, Miloš Gligorić, Jelena Majstorović, Luka Crnogorac Дигитални репозиторијум Рударско-геолошког факултета Универзитета у Београду [ДР РГФ] Analysis of a simplified model for determining ...
    ... ofjers the analysis of the simplified model for defining parameters of the oscillation equation at the Kovilovača open pit, in eastern Serbia. On the basis of calculation on concrete example of mass blasting, it has been stated that the simplified model may be used in order to calculate rock mass ...

  • Fuzzy Model for Risk Assessment of Machinery Failures

    Dejan V. Petrović, Miloš Tanasijević, Saša Stojadinović, Jelena Ivaz, Pavle Stojković (2020)
    The main goal of this research was the development of an algorithm for the implementation of negative risk parameters in a synthesis model for a risk level assessment for a specific machine used in the mining industry. Fuzzy sets and fuzzy logic theory, in combination with statistical methods, were applied to analyze the time picture state of the observed machine. Fuzzy logic is presented through fuzzy proposition and a fuzzy composition module. Using these tools, the symmetric position of the ...
    fazi teorija, rizik, otkaz rudarskih mašina
    ... fuzzy inference approach was used in an outcome calculation. The main benefit of the proposed model is being able to use numerical and linguistic data in a risk assessment model. The proposed risk assessment model, using fuzzy logic conclusions and min–max composition, was used on a mobile crushing machine ...
    ... fuzzy inference approach was used in an outcome calculation. The main benefit of the proposed model is being able to use numerical and linguistic data in a risk assessment model. The proposed risk assessment model, using fuzzy logic conclusions and min-max composition, was used on a mobile crushing machine ...
    ... incorporated this into a comprehensive model for risk level assessment for a certain machine used in the mining industry. The example of risk assessment model developed in this research is for a mobile crushing machine, the Lokotrack LT 1213S. The developed model presents a new methodological approach ...

  • Hybrid Stochastic-Grey Model to Forecast the Behavior of Metal Price in the Mining Industry

    Zoran Gligorić, Miloš Gligorić, Dževdet Halilović, Čedomir Beljić, Katarina Urošević (2020)
    cena metala, neodređenosti, prognoza, stohastički sivi model, singularna analiza spektra

  • Речници у дигиталном добу - информатичка подршка за српски језик

    Биљана Рујевић (2022)
    Морфолошки речници српског језика представљају електронски језички ресурс који има значајну историју развоја и коришћења за потребе обраде природних језика. С обзиром на то да су чувани у облику датотека чији је број нарастао па је самим тим управљање речницима постало отежано јавила се потреба за смештањем информација из речника у облик лексикографске базе. Како би се омогућио симултани рад на развоју речника за више корисника јавила се потреба за веб-апликацијом заснованој на лексикографској бази. Како би се размотриле ...
    електронски речници, лексикографска база података, лексички ресурси, српски језик

  • Rezultati geoloških istraživanja lignita Kostolačko-kovinskog ugljonosnog basena – geološke i morfostrukturne karakteristike

    Bogoljub Vučković, Biljana Radovanović, Vesna Matić, Lidija Glamočanin, Bogdan Radić, Ksenija Eraković, Dragana Životić (2022)
    Geološka istraživanja Kostolačkog basena i ležišta Kovin vrše se više od 80 godina, dok eksploatacija traje više od 100 godina. Tokom dugog perioda rudarskih aktivnosti na površini od oko 320 km2, izbušeno je preko 3.200 bušotina i više od 265.000 m jezgra. Nova saznanja o geološkim karakteristikama, morfologiji i kvalitetu ugljenih slojeva nameću neophodnost reinterpretacije i izrade jedinstvenog 3D modela Kostolačko-kovinskog basena. Primenom savremenih softverskih paketa olakšano je povezivanje ugljenih slojeva sa posebnim osvrtom na morfologiju i kvalitet slojeva i ...
    lignit, Kostolac, Kovin, geološka istraživanja, 3D model

  • Steel Arch Support Deformations Forecast Model Based on Grey–Stochastic Simulation and Autoregressive Process

    Luka Crnogorac, Suzana Lutovac, Rade Tokalić, Miloš Gligorić, Zoran Gligorić (2023)
    Relatively large deformations of the steel arch support in underground coal mines in the Republic of Serbia present one of the main problems for achieving the planned production of coal. Monitoring of the critical sections of the steel arch support in the underground roadways is necessary to gather quality data for the development of a forecasting model. With a new generation of 3D laser scanners that can be used in potentially explosive environments (ATEX), deformation monitoring is facilitated, while ...
    čelična podgrada, prognoza deformacija, vremenske serije, grey-stohastička simulacija, autoregresija, podzemni rudnik uglja

  • Geotehnički uslovi izgradnje metro stanice „Savski trg“ – beogradski metro linija 1

    Dragoslav Rakić, Nemanja Stanić, Josip Išek, Slavoljub Stojković (2023)
    Ukrštanje linija 1 i 2 beogradskog metroa, planirano je na lokaciji “Savski trg” gde će se izgraditi zajednička metro stanica. Zbog složene konstrukcije objekta i različite dubine dijafragmi, koja na delu metro linije 2 iznosi preko 40 m, planirana je fazna izgradnja. U vezi sa tim u radu je prikazan način definisanja geotehničkog modela, kao i geotehnički proračuni u kojima su analizirani: fazni načini iskopa, filtraciona analiza, uticaj pornih i efektivnih napona na stabilnost dijafragme, horizontalna i vertikalna ...
    beogradski metro, metro stanica, geotehnički model, stabilnost dijafragme, horizontalna pomeranja, vertikalna pomeranja

  • Geotehnički uslovi izgradnje nadvožnjaka "Balajnac" na autoputu E-80 deonica: Niš - Merošina

    Dragoslav Rakić, Nikola Božović (2024)
    U sklopu prve deonice autoputa E-80 Niš – Merošina, izgrađen je nadvožnjak u zoni sela Balajnac koji je oslonjen na tri stubna mesta na međusobnom rastojanju od oko 26 m. Svaki stub je fundiran na šipovima i to sa predloženim rasporedom od 2 šipa u grupi na međusobnom rastojanju od 3.6 m. U radu su na osnovu izvršenih geotehničkih istraživanja terena, analizirani rezultati nosivosti vertikalno opterećenog šipa prečnika 1.2 m i dužine šipa od L = 23 m. Analiza ...
    nadvožnjak Balajnac, šip, probno opterećenje šipa, projektni pristup, granična stanja

  • Model za optimizaciju graničnog saržaja metala u rudi u funkciji dugoročnog planiranja površinskih kopova

    Daniel P. Kržanović (2016-06-14)
    Optimizacija graničnog sadržaja metala u rudi jedan je od osnovnih koraka u planiranju i dizajniranju površinskih kopova i ima za cilj postizanje maksimalne neto sadašnje vrednosti (NPV). Iz tog razloga, optimizacija graničnog sadržaja i danas je predmet mnogih istraživanja u rudarskoj nauci, sa ciljem rešavanja praktičnih problema u eksploataciji ležišta.Dugoročno planiranje eksploatacije na površinskim kopovima podrazumeva sagledavanje svih relevantih parametara i faktora (geologije rudnog ležišta, tehnologije proizvodnog procesa, kapaciteta otkopavanja i prerade, troškova, cena metala, iskorišćenja i dr) kako ...
    površinski kop, dugoročno planiranje, optimizacija graničnog sadržaja, maksimizacija neto sadašnje vrednosti (NPV).
    ... osnovu matematičkih algoritama/modela koji su opisani u poglavljima 3.0. i 4.0. To su sledeći modeli: 1) Model za formiranje blok modela ležišta 2) Model troškova i prihoda 3) Model za ekonomsku evaluaciju projekta 4) Model za optimizaciju granice kopa i izbor faza razvoja kopa 5) Model za op ...
    ... razvijeni model, njegova ograničenja i pretpostavke i opis primenjenih matematičkih 6 modela u razvoju integralnog modela. U okviru poglavlja dat je opis prednosti koje pruža implementacija predloženog modela na realnom ležištu. Šesto poglavlje U ovom poglavlju, model opisan u petom ...
    ... (solida) Kreiranje blok modela Modeliranje topografije terena Kreiranje baze podataka Manipulacija blok modelom Slika 5.1. Algoritam razvijenog integralnog modela 211 5.6. Primenjeni matematički algoritmi za razvoj integralnog modela Integralni model za optimizaciju graničnog ...

  • A Fuzzy Expert Model for Availability Evaluation

    Dejan Ivezić, Miloš Tanasijević, Predrag Jovančić, Radiša Đurić (2019)
    Each technical system within itself carries the great potential danger of possible occurrence of failure and damages. Mining machines are characteristic by great investment values, costs of unplanned shutdowns, complex working conditions, and environment and workers hazards. Systematic monitoring of the mining machinery is of great importance for the management of the mining companies. Availability is the overall concept of quality of service. Includes information regard to operating state, an idle state, a standby state and shut down. The ...
    raspoloživost, ekspertski sistem, fazi teorija, buldozeri
    ... III. AVAILABILITY ASSESSMENT MODEL Figure 1 shows the conceptual model of the expert system for availability (A) evaluation based on fuzzy interference of reliability (R), maintainability (M) and supportability (S) input data. Input data are introduced to a model based on experts’ opinions. ...
    ... Измењено: 2023-10-14 04:10:15 A Fuzzy Expert Model for Availability Evaluation Dejan Ivezić, Miloš Tanasijević, Predrag Jovančić, Radiša Đurić Дигитални репозиторијум Рударско-геолошког факултета Универзитета у Београду [ДР РГФ] A Fuzzy Expert Model for Availability Evaluation | Dejan Ivezić, Miloš ...
    ... but requires specific, quite complex IT system. Therefore, in this paper, an expert model, that integrates reliability, maintainability, and supportability in the measure of availability is proposed. This model is based on fuzzy sets theory and it is implemented to three types of bulldozers that ...

  • Influence of DEM resolution on numerical modelling of debris flows in RAMMS - Selanac case study

    Jelka Krušić, Biljana Abolmasov, Mileva Samardžić Petrović (2019)
    Debris flows induced by intensive rainfall represent very hazardous phenomena in many parts of the World. Methods for prediction of runout distance of flow like mass movements are different and depending on the input data, rheology, and available or appropriate numerical solution. However, sometimes it is not easy to obtain pre event and post event high-resolution data in the rural or mountainous area. Thus, the topology of terrain is the most important input parameter for the every real case ...
    tecišta, modeliranje, RAMMS, DEM
    ... 2007; Frank, 2017). As input, three quantities must be specified to perform a numerical calculation: (1) a digital elevation model (DEM), (2) source zone area and (3) model friction parameters. Pre- event DEM resolution characterizes the natural terrain surface geometry and it is therefore the most ...
    ... resolution affected a lot in results about deposition depth, but also on choosing right frictional parameter in rheological model. Method One of well used rheological model is Voellmy method (Voellmy, 1955) firstly used in snow avalanche models, which means that is basically one-phase. It is assumed ...
    ... precision in calculated eroded material, which is quite deep in this case. Input Data RAMMS uses DEM (Digital Elevation Model) as a basic data for defining simple geometry of model. Some researchers suggested 5x5m resolution as an optimal, explaining that even using smaller resolution gave quite similar ...

  • Univerzitet u Beogradu Rudarsko-geološki fakultet Master rad Modeliranje disperzije prašine u životnoj sredini u fazi proširenja P.K. Veliki Krivelj

    Magdalena Milanović (2024)
    Modeliranje disperzije zagađenja životne sredine predstavlja proces u kom se korišćenjem matematičkih modela vrši simulacija širenja i raspodele zagađenja u životnoj sredini, koje nastaje određenim aktivnostima. Modeliranje nam pomaže da predvidimo zagađenja koja dobijamo planiranim aktivnostima u zemljištu, vodi i/ili atmosferi određene regije, kako bi na vreme preduzeli odgovarajuće preventivne mere kojim se smanjuje ili upotpunosti eminiše uticaj na životnu sredinu i zdravlje ljudi. Glavni zadatak ovog rada je procena uticaja, projekta proširenja kopa Veliki Krivelj, na kvalitet vazduha. Rezultati koji ...
    Modeliranje disperzije zagađenja životne sredine, površinski kop Veliki Krivelj, AERMOD, zagađenje vazduha, disperzija prašine
    ... 3. Razvoj modela: razvoj konceptualnog modela koji odražava osnove nauke o procesima koji se modeliraju, i razvoj matematičkog. predstavljanja problema i kodiranje ovih matematičkih izraza u kompjuterski program 4. BHvaluacija modela: testiranje da li su matematički izrazi u modelu programirani ...
    ... kako se procesi matematički predstavljaju i koje informatičke metode se koriste u implementaciji matematike. [5] Modeli su bazirani na pojednostavljenim pretpostavkama i ne mogu u potpunosti replicirati složenost svojstvenu realnim ekološkim sistemima. Uprkos ovim ograničenjima, modeli su od suštinske ...
    ... koeficijenta disperzije Koeficijenti disperzije (oy ı oz) u opštoj Jednačini modela Gausove disperzije su najvažniji parametri u modeliranju disperzije jer odražavaju karakteristike atmosfere u matematičkom modelu. S obzirom na oblik perjanice koja se prostire u pravcu vetra nakon ispuštanja ...

  • Numerical modeling of Selanac debris flow propagation using SPH code

    Jelka Krušić, Biljana Abolmasov, Miloš Marjanović, Manuel Pastor, Saeid M. Tayyebi (2021)
    The Selanac debris flow is a very huge event triggered after extreme rainfall caused by Cyclone Tamara activity in the Republic of Serbia in May 2014. The Selanac case study was already modelling in different programs using Voellmy rheology assumptions like RAMMS software. In this paper research are focusing particularly on the process of debris flowing from initiation zone to main deposition area using Geoflow SPH two-phase model considering frictional rheology law. Main rheological parameters are back-calculated using also ...
    debris flow, modelling, SPH code, DEM
    ... and high resolution Digital Terrain Model (DTM), also. Final models show accurate results comparing to the depths in deposition zone, but actual run-out distance of debris flow was longer than the measured run-out distance obtained by the SPH simulation model. Also, simulation results show heights ...
    ... velocity as well as pore water pressure if coupled model is included. Geoflow SPH proposed by Pastor 2009, already has been used on different cases in the world (Pastor et al. 2015, 2009, Cascini et al. 2014, Cuomo et al. 2014).Within the SPH model, it is possible to incorporate numerous rheological ...
    ... SPH model proposed by Pastor et al. (2009), defines propagations of mass as mixture of soil and water particles with calculation of velocity. In addition, calculation of pore water pressures propagation is possible to be obtained using Finite Difference Method coupled with two- phase model. Herein ...