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Упит dcterms_subject_txt:top-down method

519 items

  • Application of Expansive Mortars for the Formation of Artificial Screens During Blasting in Urban Areas

    Milanka Negovanović, Lazar Kričak, Stefan Milanović, Nikola Simić, Jelena Majstorović (2024)
    During construction of buildings in urban areas, sometimes there is a need to blast solid rock mass in the immediate vicinity of the surrounding buildings. In that case, the aim is not only to increase the efficiency of blasting, but also to reduce harmful effects of ground vibration induced by blasting. At the same time, it is very important to protect the buildings located in the safe zone from the blast site as well as remaining rock mass around ...
    expansive mortar, artificial screens, pressure, rock breaking, building foundation

  • Refinement of waste phosphogypsum from Prahovo, Serbia: characterization and assessment of application in civil engineering

    Josip Išek, Lazar Kaluđerović, Nikola Vuković, Maja Milošević, Ivana Vukašinović, Zorica Tomić (2020)
    γ-spectrometry, brushite, chukhrovite, phosphogypsum, radionuclides, recrystallization
    ... Th are transferred into the phos- phoric acid. Through these chemical processes, the secular equi- librium between the specific decay series breaks down. The main objective of this study was to extract and character- 23; ize purified gypsum, as well as phosphogypsum. A secondary ol radionuclide ...
    ... of the samples' containers, and the purified gypsum sample was measured once, after the con- tainer was sealed. By applying the y-spectrometry method, the activity concen- tration of _ŠU was determined from its decay products Th (63keV) and/or "Pa (1000 keV). The ecay products of ? Ra, _ Bi (609 ...
    ... similar result was obtained with calcium sulfate whiskers synthesized from flue gas desulfurization of gypsum using the atmospheric acidification method (Sun ef al., 2016). Whiteness index The WI of 52.5%, determined for raw phosphogypsum (PG1), is too low for potential use in some industries ...

  • 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)
    ... specific work environment and by particular blasting conditions. 2.2.1. 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 representing a common model [5,6]. 2.2.2. Model 2—Determining the Parameters by Applying ...
    ... determination of parameters K and n in the Sadovskii equation. To determine the parameters in the Sadovskii formula, in addition to the usual least square method, two more new models were applied. In the models the parameters K and n were determined by applying the quotient of the relative growth of oscillation ...
    ... friction, φ = 52˝; ‚ porosity, p = 3.5%; ‚ velocity of longitudinal waves, cp = 2400.00 m/s; ‚ velocity of transverse waves, cs = 1400.00 m/s. 4.1.2. Method of Blasting in the Veliki Krivelj Open Pit The measurements of shocks resulting from blasting in the Veliki Krivelj Open Pit were performed during ...

  • 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)
    ... models, using the values obtained by experimental measurements. 3.3.1. 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 [9,10]. 3.3.2. Model 2—Determining the Parameters through ...
    ... and B from (58) and (59) are put into Equation (27), we get: y + 3 = −0.8891x + 5.2588. (60) Since y = logv, x = logR, then the Equation (60) comes down to equation: logv + 3 = −0.8891logR + 5.2588. (61) Figure 5 graphically represents the values of logarithms of the rock mass oscillation velocities ...
    ... characteristics of the rock mass, and it is determined based on trial blasting for a specific work environment. Thus, this paper offers analysis of the method for determination of parameters of the rock mass oscillation equation, which are conditioned by rock mass properties and blasting conditions. Practical ...

  • Моделирање утицаја одступања линије најмањех отпора од пројектоване на интензитет потреса од минирања

    Стефан Милановић (2024)
    Према дефиницији линија најмањег отпора представља најкраће растојање од центра минског пуњења до слободне површине. Oвим истраживањем представљен је утицај линије најмањег отпора, као и њеног одступања од пројектоване на интезитет потреса услед минирања. Проблем линије најмањег отпора је веома заступљен у пракси, где се занемарује изглед слободне површине, који може бити врло неправилан. Линију најмањег отпора је потребно мерити целом дужином минске бушотине према слободној површини, иако је у пракси случај да се мери најчешће као растојање од ...
    линија најмањег отпора, 3D модел, потреси услед минирања, минирање, слободна површина, метода раздвојених елемената

  • Design and drilling of wells in formations with high pressure

    Vojin Solomun (2024)
    Objectives of this Thesis are to: - Develop an awareness of the challenges presented from elevated temperatures and pressures in well construction. - Learn the key differences between ―normal‖ condition wells and HPHT wells. - Understand some of the indicators of thermal- and pressure-related problems. - Understand the responses which may be made to mitigate high pressure and high temperature ,,HPHT‘‘ challenges while drilling wells. HPHT wells are an unavoidable consequence of the ever expanding search for oil and gas resources around the world. As wells are ...
    HPHT, well, challenges, design, oil and gas
    ... (NExT), 2016. Driller's Method, Wait & Weight Method, Volumetric The Driller's Method is the simpler well control procedure, although ıt takes longer, requiring two circulations (at least), which is a significant issue in expensive wells. The Wait and Weight method is viewed by many as “too complex” ...
    ... Maintain rheological properties of the mud and a reduction in the used of additives; Reduction of corrosion of the drill pipe and down-hole tools, performance of down-hole motors, MWD/LWD tools; Increased Bit Life Increased transportation of drilling cutting back to the surface. Mud Cooler (picture ...
    ... Picture 8.14 — BOP stack (NExT, 2016.) Well Control Program - Procedures such as shut-in method, flow checks, circulating rates, kill method to be utilized and alternatives to use if primary kill method does not work, must be established prior to drilling the well and defined in the WCPP. A ...

  • The Reciprocal Algebraic Integers Having Small House

    Dragan Stankov (2021)
    Algebraic integer, the house of algebraic integer, maximal modulus, reciprocal polynomial, primitive polynomial, Schinzel-Zassenhaus conjecture, Mahler measure, method of least squares, cyclotomic polynomials

  • Sinteza i karakterizacija nanoprahova u CeO2-Bi2O3 sistemu

    Marija D. Prekajski (2014-04-04)
    Nanoprahovi kristalnih faza iz serije čvrstih rastvora u pseudo-binarnom sistemuCeO2-Bi2O3 sintetisani su primenom jednostavne i ekonomične samopropagirajućemetode na sobnoj temperaturi korišćenjem nitrata metala i natrijum-hidroksida kaopolaznih supstanci. Osim krajnjih članova niza, CeO2 i niskotemperaturne polimorfnemodifikacije α-Bi2O3, sintetisani su i čvrsti rastvori nominalnog sastava Ce1-xBixO2-δ,gde je x = 0,1; 0,2; 0,3; 0,4; 0,5; 0,6; 0,7; 0,8; 0,9. Rezultati proučavanja metodomrendgenske difraktometrije na polikristalnom materijalu i ramanske spektroskopskeanalize pokazali su da su sintetisani prahovi sa nižim sadržajem bizmuta (x = 0,1 ...
    nanostrukturni materijali, čvrsti rastvori, CeO2, Bi2O3, rendgenskadifraktometrija praha, Ritveldova metoda, mikrostrukrurna analiza

  • Kristalne strukture Cs2HoSi4O10F i Cs2TmSi4O10F

    Predrag Dabić, Sabina Kovač, Aleksandar Kremenović (2021)
    ... previously unknown chemical composition - Cs2HoSi4O10F and Cs2TmSi4O10F were obtained in form of single crystals. The compounds were synthesized by the method of crystal growth from a high-temperature solution (Tmax = 1373 K) using REE2O3 (REE = Ho, Tm), SiO2 and CsF as starting materials. The crystal ...

  • Postojeće stanje i budući trendovi u preventivnoj zaštiti podzemnih voda Srbije

    Vladimir Živanović (2022)
    Podzemne vode predstavljaju osnovni, a u mnogim zemljama i jedini resurs za javno vodosnabdevanje stanovništva tako da zaštita podzemnih voda predstavlja bitan preduslov za njihovo dugotrajno i održivo korišćenje. Kako u svetu, tako i u Srbiji, zaštita podzemnih voda se najvećim delom svodi na primenu preventivnih mera zaštite. Kod planiranja zaštite većih prostora sve više se koriste metode za ocenu ranjivosti podzemnih voda. Njihova primena je posebno naglašena u karstnim područjima zato što se tu izdvajaju delovi terena sa ...
    Zaštita podzemnih voda, karte ranjivosti podzemnih voda, karta hazarda, karte rizika od kontaminacije, monitoring podzemnih voda, Srbija

  • Review: Methodological approaches and research techniques for addressing construction and remediation problems in karst reservoirs

    Saša Milanović, Ljiljana Vasić (2021)
    Earth and Planetary Sciences (miscellaneous), Water Science and Technology

  • Аnaliza mogućnosti povećanja nagiba završne kosine površinskog kopa “Podbraćan”

    Vladimir Čebašek, Veljko Rupar (2018)
    Eksploatacijom boksita iz ležišta "Podbraćan" formiran je površinski kop sa maksimalnom visinom zavšne kosine od 280 m. Redovnom kontrolom stabilnosti trenutnog stanja kosina površinskog kopa utvrđeno je da faktor sigurnosti iznosi Fs = 1.71 – 1.85, a što je ukazalo da postoji mogućnost povećanja nagiba kosine. U radu je prikazan postupak analize mogućnosti povećanja nagiba završne kosine površinskog kopa "Podbraćan".
    stabilnost kosina, povećanje nagiba kosina, metoda konačnih elemenata

  • FTIR spectroscopic study оf S-мetolachlor сorption оn inorganic and organically modified montmorillonite from Bogovina

    Lazar Kaluđerović, Zorica Tomić, Jelena Bogosavljević, Ljubomir Životić, Maja Milošević (2021)
    ... was collected from the Bogovina locality (Serbia). Clay fraction, with montmorillonite as the dominant mineral, was separated using the decantation method. Clay fraction (< 2 mm) was then treated with 30% hydrogen peroxide in order to remove organic matter from the sample. 330 SERBIAN SOCIETY OF ...
    ... and marked as NaM-SM, 1H-SM, 2H-SM, 3H-SM, 4H-SM, IP-SM, 2P-SM, 3P-SM, and 4P- SM. FTIR spectroscopy All samples were investigated using FTIR method (Fourier-transform infrared spectroscopy). All results were obtained in Laboratory for infrared spectroscopy at the Faculty of Science, University ...
    ... Figure 3. Suggested interactions betveen PTMA*cations and phenolin interlayerspace of montmorillonite (Majdan et al., 2009) CONCLUSION FTIR method was very useful in the process of examination of interactions between Na- montmorillonite and organic complexes such as HDTMA bromide and PTMA chloride ...

  • 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

  • Natural two-dimensional pyrophyllite: Nanoscale lubricant, electrical insulator and easily-machinable material

    Borislav Vasić, Radoš Gajić, Ivana Milošević, Žarko Medić, Marina Blagojev, Marko Opačić, Aleksandar Kremenović, Dejan Lazić (2022)
    Pyrophyllite, with the chemical formula Al2Si4O10(OH)2, is a naturally occurring and abundant van der Waals mineral belonging to the group of phyllosilicates. It is very soft, layered crystal used for sculpting and an excellent electrical and thermal insulator aimed for the operation at high pressure and temperature. Here, for the first time, two-dimensional (2D) pyrophyllite obtained by both mechanical and liquid phase exfoliation is presented and investigated at the nanoscale. The layered structure provides low friction coefficient of around ...
    Atomic force microscopy, Insulating properties, Nanofriction and wear, Natural two dimensional materials, Phyllosilicates, Pyrophyllite

  • Hydrochemical features and their controlling factors in the Kucaj-Beljanica Massif, Serbia

    Fen Huang, Ljiljana Vasic, Xia Wu, Jianhua Cao, Saša Milanovic (2019)
    Earth-Surface Processes, Geology, Pollution, Soil Science, Water Science and Technology, Environmental Chemistry, Global and Planetary Change

  • Mesozoic carbonate rocks in Serbia used as dimension stone

    Vesna Matović, Tijana Vojnović Ćalić (2016)
    The building industry in Serbia uses, to a great extent, imported natural stone for architectural purposes. The significance of local deposits, particularly limestones, is not adequately perceived despite the country’s abundance of these valuable resources. Therefore, this study focuses on Serbia’s Mesozoic carbonate rocks, specifically on the deposits of four selected quarries: Klisura, Skrzut, Struganik, and Tisnica. The quality and prospects of the application of these limestones has not yet been the subject of a detailed, comprehensive investigation. Therefore, ...
    Ukrasni kamen, Mezozoik, Krečnjak, Srbija, Petrografija, Fizičko-mehanička svojstva
    ... density was determined according to the standard method SRPS B.B8.032 (1980) (corresponding to Euro- pean Committee for Standardization EN 1936:2006). On the same, but powdery samples, the real densities were determined using a pycnometer method. Considering the values of real and bulk density ...
    ... ion, according to Folk (1959) and Flugel (2004). The CaO and MgO contents were determined for the same samples, applying: a complexo- metric method using a standardized solution of 1 MEDTA (ethylenediaminetetraacetic acid) as the titrant. To determine the quality of the selected carbonate rocks ...
    ... density, the total porosity was calculated. The water absorption was determined according to the standard method SRPS B.B8.010 (1981) (corre- sponding to European Committee for Standardization EN 13755:2009). The resistance to frost was determined by @ Springer subjecting the sample to 25 cycles ...

  • Crystallography and Surface Oxidation of Stoichiometric Arsenopyrite from Šumadija-Kopaonik Pb-Zn/Polymetallic Ore District (Serbia)

    Ivana Jelić, Aleksandar Pačevski, Aleksandar Kremenović, Aleš Šoster, Andreja Šestan, Janez Zavašnik (2023)
    The behaviour and stability of arsenopyrite largely depend on its crystal structure, but studies of crystallography and structural defects are scarce. For clarification, we investigated a series of natural arsenopyrite crystals from the polymetallic Pb-Zn-(±Cu,Ag,Au,Sb,Bi,W) Šumadija-Kopaonik ore district (Serbia) by powder X-ray diffraction (XRPD). Among them, samples from the Drenjak gold mineralisation showed near-stoichiometric FeAsS composition and were further investigated by conventional and high-resolution transmission electron microscopy methods. TEM revealed abundant planar crystallographic defects and epitaxial surface oxide layer ...
    Inorganic Chemistry, Condensed Matter Physics,General Materials Science, General Chemical Engineering, crystal structure, FeAsS, oxidation, TEM, XRPD
    ... Gatan Inc., Pleasanton, CA, USA) in a #3 mm brass tube, and sliced and polished into 100 um disks. The disks were further thinned at he disk centre down to 10 m (Dimple Grinder Mod. 656, Gatan Inc., Pleasanton, CA, 'USA) and Ar? ion-etched until perforation by a precision ion polishing system (PIPS ...
    ... depth profiling suggest, upon 30 min air exposure, the formation of a total 5 nm thick surface structure composed of three layers, starting, with the top ~2 monolayers of FeOOH, followed by FexAsyO and Fei-x„.,AsnyS [23], which does not coincide with our observations. A longer oxidation of 25 days ...
    ... any variation in the cell parameters, indicating a single-layer surface crystalline oxide structure with additional thin amorphous Fe-hydroxide on top. It is worth mentioning that such an oxidation structure Was not observed on the samples directly transferred from the vacuum chamber to the TEM ...

  • Mapping and classifying large deformation from digital imagery: application to analogue models of lithosphere deformation

    Taco Broerse, Nemanja Krstekanić, Cor Kasbergen, Ernst Willingshofer (2021)
    kontinentalna tektonika: kompresija, kontinentalna tektonika: ekstenzija, kontinentalna tektonika: transkurentni i transformni rasedi, pukotine, rasedi, zone snažnih deformacija, kinematika deformacija kore i omotača, teorijska mehanika, modelovanje
    ... region, along the E–W oriented velocity discontinuity, two zones of shortening evolve. This early structural pattern consists of a top-to-N basal thrust (2) and one top-to-S backthrust (3). D o w n lo a d e d fro m h ttp s ://a c a d e m ic .o u p .c o m /g ji/a rtic le /2 2 6 /2 /9 8 ...
    ... panels: cross-sections at three different locations. The top two sand layers have been added after finalizing the model to stabilize the model topography; the black dashed line indicates the original model topography. Cross-section a–a’ (top right) shows the main N-S dextral strike-slip zone, with ...
    ... described based on the relative magnitude of the two principal Hencky strains. Thereby, our method introduces a physically meaningful classification of large 2-D strains. We show that our strain type classification method allows for accurate mapping of tectonic structures in analogue models of lithospheric ...

  • Analysis Of the Process Of Carbon Capture Utilization And Storage In Underground Reservoirs

    John Nyame (2024)
    The importance of mitigating the effects of global climate change has necessitated an in-depth exploration of innovative strategies to reduce carbon dioxide (CO2) emissions. Among these strategies, Carbon Capture, Utilization, and Storage (CCUS) has emerged as a promising and transformative solution. This master thesis delves into the diverse realm of CCUS processes, aiming to unravel the positives challenges, and opportunities within this dynamic field. The analysis begins with a systematic examination of carbon capture technologies, encompassing post-combustion, pre-combustion, and oxy-fuel combustion ...
    Carbon Capture, Utilization and Storage
    ... the price of gas and the effectiveness of recovery [61]. Figure 4.5 shows an enhanced oil recovery method used to store CO». CO>/water „~# injection __I Figure 4.5 Enhanced oil recovery method 4.3. Replacement of Methane in Coal Beds Coal contains fractures that impart some permeability to ...
    ... chemical and physical solvents and used mostly for precombustion and post combustion[38]. Absorption is a mature and well- established separation method that results in high capture efficiency however the energy cost incurred is very high mainly because of the high energy requirements for the solvent ...
    ... ANALYSIS Carbon utilization can be an important option for providing an alternate source of renewable energy to produce various products. The method must be ecofriendly, economically viable and safe [12]. Carbon utilization plays a crucial role in transitioning to a carbon-neutral future, as ...