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Упит dcterms_subject_txt:top-down method

507 items

  • The number of nonunimodular roots of a reciprocal polynomial

    Dragan Stankov (2023)
    We introduce a sequence Pd of monic reciprocal polynomials with integer coefficients having the central coefficients fixed as well as the peripheral coefficients. We prove that the ratio of the number of nonunimodular roots of Pd to its degree d has a limit L when d tends to infinity. We show that if the coefficients of a polynomial can be arbitrarily large in modulus then L can be arbitrarily close to 0. It seems reasonable to believe that if ...
    Algebraic integer, the house of algebraic integer, maximal modulus, reciprocal polynomial, primitive polynomial, Schinzel-Zassenhaus conjecture, Mahler measure, method of least squares, cyclotomic polynomials

  • Structural and microstructural study of brookite based TiO2 nanocomposites with carbon black (C)

    Aleksandar Kremenović, Mirjana Grujić-Brojčin, Nataša Tomić, Maja Šćepanović (2022)
    Structural and microstructural properties of TiO2-based nanocomposites with carbon black (C), synthesized by sol-gel-hydrothermal method, have been studied by XRPD and Raman scattering. Detailed size-strain analyses of XRPD and Raman scattering results are presented in order to investigate the influence of C content on brokite and anatase phase formation. The XRPD size-strain analyses have resulted in reliable structure and microstructure results for both anatase and brookite and their relative abundance ratio has been refined by Rietveld method. The brookite ...

  • Correlation of uniaxial compressive strength with the dynamic elastic modulus, p –wave velocity and s –wave velocity of different rock types

    Jelena Majstorović, Miloš Gligorić, Suzana Lutovac, Milanka Negovanović, Luka Crnogorac (2019)
    Knowing mechanical properties of rocks incorporated with ultrasonic waves velocities investigations provide a secure basis for mine modelling. Uniaxial compressive strength, dynamic elastic modulus and ultrasonic waves velocities are just some of the rock properties that indicate on presence of discontinuities, stratification and fissures of rocks. Determining the relationship of these rock properties testing the rock samples that are corresponding to different rock types extracted from different mineral deposits represents the core of this study. In this paper, we ...
    линеарна регресија, метода најмањих квадрата, динамички модул еластиности, брзина уздужних таласа

  • Određivanje prostorne distribucije vrednosti hidrauličkih parametara izdani: primer površinskog kopa „Radljevo“

    Dragoljub Bajić, Dušan Polomčić, Jelena Ratković, Predrag Pajić (2019)
    Najčešće se kalibracija hidrodinamičkih modela vršila manuelno - „probanjem“ sa različitim vrednostima hidrauličkih parametara i hidrauličkih karakteristika graničnih uslova. Ovakav način rada zahteva veliko znanje i iskustvo eksperta, pri čemu ostaje otvoreno pitanje da li dobijeno rešenje ima optimalan skup parametara. Primenom optimizacione metode, koja se zasniva na Gauss-Marquardt-Levenberg-ovom algoritmu, i PEST softvera, ...
    kalibracija hidrodinamičkog modela, PEST, koeficijent filtracije

  • Mine surveying works for the purpose of excavating the remaining reserves of bauxite in the deposit of “Podbracan”

    Aleksandar Milutinović, Aleksandar Ganić, Thamer Rayes Diyab, Rade Tokalić, Meri Ganić (2015)
    ... smaller than the maximum allowable tolerance. Therefore, this value, which is obtained by using the a priori accuracy assessment method, does not need to be broken down to longitudinal and lateral components. The additional analysis of standard deviation for the position of the last point E420-10 ...
    ... works for the purpose of excavating the remaining reserves of bauxite in the deposit of "Podbracan" 4.1. Mining method The applied mining method, named the sublevel caving excavation method in crosswise direction, was chosen based on the relevant mining- geological parameters, mining condi- tions and ...
    ... was designed. In the course of this, the following capital objects were constructed: the adit Jadar with length of over 2km; the main ventilation down- cast; drifts H-484 and H-448; power substation chamber at level +448m. 325 Aleksandar Milutinovic et al. REM: R. Esc. Minas, Ouro Preto, 68(3) ...

  • Application of MCDA in the determination of optimal block size for open-pit modelling and mine planning

    Petar Marković, Dejan Stevanović, Milica Pešić Georgiadis, Mirjana Banković (2021)
    The process of creating a geological block model as the basis for a further detailed design and planning of mining operations is a very responsible task. Errors made during this initial process are transferred to all other phases of the mining project. Certainly, one of the most important decisions for the modelling process is the choice of the appropriate size of the blocks that form the model itself. The determination of the optimal block size is not a simple ...
    dimenzije minibloka, višekriterijumska analiza, AHP, modeliranje ležišta, planiranje na površinskim kopovima

  • Komparacija metoda XRF i ICP-MS na uzorcima uglja i produkata sagorevanja

    Branko Kostić, Dejan Prelević, Sabina Kovač, Ksenija Eraković, Dragana Životić (2022)
    Ugljevi niskog ranga – ligniti u Republici Srbiji predstavljaju glavnu energetsku sirovinu koja se koristi za proizvodnju električne energije. Rudarstvo u Srbiji doprinosi bruto dodatoj vrednosti sa 1,8% (2020; https://publikacije.stat.gov.rs/). Sagorevanjem ugljeva niskog ranga u termoelektranama generišu se velike količine elektrofilterskog pepela i pepela, koje često predstavljaju jedan od izvora zagađenja životne sredine usled sadržaja toksičnih elemenata. Dalja upotreba produkata sagorevanja zavisi od njihovog sastava i sadržaja toksičnih mikroelemenata. Svakodnevno sagorevanje lignita u termoelektranama uslovljava konstantan monitoring potencijalno toksičnih ...
    ugalj, produkti sagorevanja, XRF, ICP-MS

  • 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
    ... closing. The valves transfer fluid from the bottom chamber to the top chamber and ultimately into the tubing and up to the wellhead.The mechanical method of oil production using rod pumps, as illustrated in Figure 1.1, is the oldest method for bringing fluids from wells to the surface and is also the ...
    ... conditions. [5] Insert pumps can be classified based on their seating method into: • Bottom Seating Pumps (a) • Top Seating Pumps (b) • Double Seating Pumps (c) a 6) B) Figure 3.5. llustration of Insert Pumps by Seating Method [5] 18 (b) Rod . O Figure 3.6. Tubing pump and Insert Pump ...
    ... — API Method — Wave Equation API method This method was developed in 1956 at the Research Institute of the city of Kansas in the USA by manufacturers and users of deep well pump equipment. It is more precise than the empirical method, with the main difference being that the API method takes ...

  • Classifying large strains from digital imagery: application to analogue models of lithosphere deformation

    Taco Broerse, Nemanja Krstekanić, Cor Kasbergen, Ernst Willingshofer (2021)
    ... interpretation of this deformation, we have developed a novel method thatcan qualitatively describe shape changes coming from extensional, shortening and horizontalshearing (strike-slip) deformation or combinations of these. This method is based on a logarithmicmeasure of stretch and results agree well ...
    ... internaldeformation, such as faults, and broader zones of deformation. We use Particle Image Velocimetry(PIV) to derive incremental displacements from top-view images that we use in subsequent stepsto calculate the shape changes that come with large deformation. Because PIV describesdisplacement in a spatial ...
    ... our models. Thus, we provide tools with which the evolution of 2D tectonic deformationcan be interpreted in a physically meaningful manner, but our method may be useful outside therealm of tectonics. Our software to compute deformation is freely available and can be used topost-process incremental di ...

  • Ground surface subsidence monitoring using sentinel-1 in the “Kostolac” open pit coal mine

    Zoran Gojković, Milan Kilibarda, Ljiljana Brajović, Miloš Marjanović, Aleksandar Milutinović, Aleksandar Ganić (2023)
    Open pit coal mining affects surrounding populated areas, resulting in terrain surface deformation. Surface deformation should be monitored as often as possible to control deformations and prevent potential incidents. This paper analyzes time series deformation estimated from the Sentinel-1 satellite images using the Persistent Scatterer Interferometry method to monitor subsidence rates caused by open pit mining activities. It is possible to measure deformations using classical geodetic methods, but those are rarely used in practice because they are time-consuming and ...
    Sentinel-1 InSAR, слегање, рударствo, интерферометрија, даљинска детекција, Костолац

  • Evaluation And Perspectives Of Underground Coal Mines In Serbia

    Vladimir Milisavljević, Milena Lekić, Ivica Ristović, Vojin Čokorilo, Aleksandar Cvjetić (2017)
    ... using the Analytic Hierarchy Process method, as described in following chapter. AHP evaluation of underground coal mines in Serbia The Analytic Hierarchy Process (AHP) is a multi-criteria decision-making approach introduced by Saaty [4]. The AHP method enables users to determine the weights ...
    ... to whether output and productivity could be increased and whether there are enough resources to justify the necessary investment. Based on AHP method and scores allocated for each factor, the mines were ranked according to technical potential. Key words: Underground mining, Potential, Restructuring ...
    ... weights of the parameters in the solution of a multi-criteria problem. In the AHP method, a hierarchical model consisting of objectives, criteria, sub-criteria and alternatives is used for every problem [5]. Solving a problem using AHP is carried out using the weights or priorities of the criteria ...

  • Prirodna ranjivost karstnih izdani srednjetrijaskih krečnjaka u oblasti između reka Bistrice, Uvca i Lima

    Branislav Petrović, Veljko Marinović, Zoran Stevanović (2022)
    karstna izdan, Priboj, prirodna ranjivost izdani, COP metoda

  • Multicriteria Analysis and Optimization of Groundwater Control Systems with Variable Values of Criterion over Predefined Time Points

    Milica Stepanović, Dragoljub Bajić, Dušan Polomčić (2021)
    VIKOR метода, алтернативе, компромисно решење, подземне воде, одводњавање рудника

  • Correlation Between Dynamic CBR and Compaction and Bearing Capacity of Pavement Foundation Layers

    Milan Bogdanović, Snežana Bogdanović, Dragoslav Rakić, Irena Basarić Ikodinović (2024)
    This paper presents a dynamic California Bearing Ratio (CBRd) device that can be used on a prepared pavement foundation layer to obtain a certain parameter of the tested material in the laboratory and in situ in a direct and fast way. For the selected natural material (gravel), it is shown that the laboratory CBRd can be used to estimate the compaction and bearing capacity, because it correlates well with the parameters of the standard and modifed Proctor compaction tests. ...
    korelacija parametara, donji slojevi saobraćajnica, laboratorijska i terenska ispitivanja, dinamički kalifornijski indeks nosivosti CBRd
    ... determined, and the physical-me- chanical parameters are defined based on laboratory testing for incorporation into the substrate layer; – the method of using a non-standardized dynamic California Bearing Ratio (CBR,) device and the defi- nitions of its values under laboratory and field conditions ...
    ... layers were established. The results of CBR, are extremely underrepresented in the literature, probably owing to the low preva- lence of this method worldwide. The first CBR, study considered mineral materials for roads [1] and report- ed good correlation between static and dynamic test results ...
    ... reported [4]. Owing to its short duration and ease, CBR, testing using a LWD can become widespread as an alterna- tive to the classic quality control method in the process of compaction or estimation of the substrate bear- ing capacity [5]. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov ...

  • Poboljšanje geotehničkih uslova izgradnje nasipa upotrebom geosintetika

    Anastasija Radovanović (2024)
    Za potrebe izrade rada na Master akademskim studijama ,,Rudarsko-geološkog fakulteta,,, studijskog programa Geotehnika, pod mentorstvom prof. dr Gordane Hadži-Niković , izvršena je detaljna analiza stabilnosti kosina nasipa na Vranjskoj petlji. Geotehnička istraţivanja i ispitivanja terena izveo je “Zavod za geotehniku iz Instituta za puteve a.d. Beograd”, a investitor je “Javno preduzeće, Putevi Srbije”.Metodološki pristup koji je korišćen za analizu stabilnosti kosina nasipa jeste kabinetsko istraživanje dostavljene dokumentacije i geostatički proračuni analize stabilnosti kosina nasipa, korišćenjem savremenih softverskih alata.Krajnji zaključak izvedenih istraţivanja je da ...
    tlo, nasip, analiza stabilnosti, faktor sigurnosti, geosintetici
    ... | Water Surface | Constant PL-p - 19 Mohr-Coulomb 0 34 | Water Surface | Constant PL-LP. - 19.5 Mohr-Coulomb 21 23 | Water Surface | Constant Method: bishop simplified FS: 0.685858 Center: 120.227, 101.900 Radius: 48.006 Left Slip Surface Endpoint: 83.058, 71.518 Right Slip Surface Endpoint: ...
    ... 0 36 | Water Surface | Constant PL-p 19 Mohr-Coulomb 0 34 | Water Surface | Constant PL-LP. 19.5 Mohr-Coulomb 23 | Water Surface | Constant Method: gle/morgenstern-price FS: 0.682043 Center: 120.227, 101.900 Radius: 48.006 Left Slip Surface Endpoint: 83.058, 71.518 Right Slip Surface Endpoint: ...
    ... | Water Surface | Constant al-sg - 20 Mohr-Coulomb |} 34 | Water Surface | Constant PL-P - 19.5 Mohr-Coulomb 21 23 | Water Surface | Constant Method: bishop simplified FS: 0.696365 Center: 27.192, 69.661 Radius: 43.383 Left Slip Surface Endpoint: 50.250, 32.914 Right Slip Surface Endpoint: ...

  • Improving Document Retrieval in Large Domain Specific Textual Databases Using Lexical Resources

    Ranka Stanković, Cvetana Krstev, Ivan Obradović, Olivera Kitanović (2017)
    Large collections of textual documents represent an example of big data that requires the solution of three basic problems: the representation of documents, the representation of information needs and the matching of the two representations. This paper outlines the introduction of document indexing as a possible solution to document representation. Documents within a large textual database developed for geological projects in the Republic of Serbia for many years were indexed using methods developed within digital humanities: bag-of-words and named ...
    ... initial method. Figure 11 depicts the MAP for all 55 queries over the six ranking methods for indexed documents and the initial method. The worst performing ranking method lnu ltu has an almost three times better performance than the initial method, whereas the results for the best performing method InQuery ...
    ... the results of the tfc tfc method were omitted as they were identical to the results of the tfc nfc method. The precision of the initial system is in general better among first-ranked documents than in the case of the improved system, with the excep- tion of the InQuery method, while the recall is better ...
    ... ascending order of the difference between the best per- forming ranking method for indexed documents InQuery and the performance of the initial method, and the results are depicted in Fig. 7. Fig. 7. Differences between initial method and InQuery indexing sorted in ascending order. We shall now discuss ...

  • Defining location and dip of magnetic anomaly sources applying mathematical transformation

    Snežana Ignjatović, Milanka Negovanović (2022)
    It is significant to define the location and dip of anomaly sources during the geophysical exploration (magnetic, gravity, electric, seismic, etc.). In this paper we presented results obtained during magnetic survey. Applying different method of mathematical transformations on magnetic data we can find the position (edge) and dip of magnetic anomaly sources. For successful solution of this problem, we used combination two method tilt derivative and upward continuation. The study area located in the eastern Serbia, north part of ...
    magnetic data, tilt derivative, upward continuation, pluton Valja Strž

  • Development of integrated fuzzy model for mine management optimization

    Miodrag Čelebić, Sanja Bajić, Dragoljub Bajić, Dejan Stevanović, Duško Torbica, Vladimir Malbašić (2023)
    fuzzy logika, višekriterijumsko odlučivanje, ocenjivanje eksperata
    ... n sciences, 8, 199—249. Š| CHANG D. Y. (1996) Applications of the extent analysis method on fuzzy AHP, Rur. J. Oper. Res., 95, 649 655. “} ZnU K., Y. JING, D. CHANG (1999) A discussion on extent analysis method and applications of fuzzy AHP, Eur. J. Oper. Res., 116, 450 456. TOLGA FE., M. DEMIRCAN ...
    ... Analytic Hierarchy Process to Underground Mining, Method Selection, Sym- metry, 12(2), 192, DOI: https://doi.org/10.3390/sym12020192. Š| NAMIN P. S., A. GHApI, P. SAK (2022) A literature review of Multi Criteria Decision-Making (MCDM) towards mining; method selection (MMS), Resources Pol- icy, 77, 102676 ...
    ... to alternative solutions plays a major role in optimal decision making. The solutions are optimized by fuzzy extent analysis, applying the FAHP method described in |*|. The optimization procedure and decision making; are presented in seven steps [12]. Step 1. Mathematical optimization begins with ...

  • 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)
    ... adsorption method was used to measure the efficiency of inorganic and organic modified montmorillonites for the sorption of the S-metolachlor. Mineralogical characterization of natural clay samples was performed using the X-ray diffraction method. This method was also used ...

  • Overwiew of In-Pit Crushing & Conveying Technology in Open Pit Mines

    Ali Nasirinezhad, Dejan Stevanović, Dragan Ignjatović, Petar Marković (2021)
    The conditions under which contemporary surface mining operations is carried out obviously becoming increasingly complex. In such complex conditions, the optimization of haulage systems as the technological phase with the largest share in the total operating costs, is very important from the aspect of achieving profitability of the mining project. In a large number of cases, the application of traditional haulage systems with trucks (as the most dominant type of haulage in open pit mines) does not lead to ...
    In Pit Crushing and Conveying, IPCC, open pit mining, haulage, optimization, costs saving