Filomat
• 15 Jun 2018
Petrović, Ljiljana • Valjarević, Dragana
In this paper we consider the concept of statistical causality between filtrations associated with
stopping times, which is based on Granger’s definition of causality. Especially, we consider a generalization
of a causality relationship ”G is a cause of E within H” from fixed to stopping time. Then we apply the
given causality concept to local uniqueness for the solution of the martingale problem. Also, we give some
applications in finance.
FILOMAT
(Faculty of Sciences and Mathematics, University of Nis)
• 01 Apr 2024
Petrović, Milena
A hybrid accelerated model with two step length parameters for solving unconstrained optimization problems is presented. Applied hybridization process involves an efficient three term hybrid method. The accelerated double step size model is taken as guiding operator in this hybridization process. Defined method is convergent on the set of uniformly convex functions as well as on the set on strictly convex quadratics. We display a Dolan Moré performance profiles of derived iteration and of some o ...
Mathematical Problems in Engineering
(Hindawi)
• 06 Nov 2018
Petrović, Milena • Stanimirović, Predrag • Kontrec, Nataša • Mladenović, Julija
We present a hybridization of the accelerated gradient method with two vector directions. This hybridization is based on the usage of a chosen three-term hybrid model. Derived hybrid accelerated double direction model keeps preferable properties of both included methods. Convergence analysis demonstrates at least linear convergence of the proposed iterative scheme on the set of uniformly convex and strictly convex quadratic functions. The results of numerical experiments confirm better performan ...
Journal of Engineering Mathematics
• 01 Apr 2024
Maksimović, Miroslav
Hyperbolic towers are towers in the shape of a single-sheet hyperboloid, and they are interesting in architecture. In this paper, we deal with the infinitesimal bending of a curve on a hyperboloid of one sheet; that is, we study the flexibility of the net-like structures used to make a hyperbolic tower. Visualization of infinitesimal bending has been carried out using Mathematica, and some examples are presented and discussed.
Photonics
(MDPI)
• 23 Feb 2022
Savović, Svetislav • Djordjevich, Alexandar • Savović, Isidora • Drljača, Branko • Simović, Ana • Min, Rui
We studied the effect of mode coupling on the space division multiplexing (SDM) capabilities of multimode step-index (SI) air-clad silica optical fibers by numerically solving the power
flow equation. Mode coupling considerably reduces the length of these fibers at which space division multiplexing may be achieved with minimal crosstalk between neighboring optical channels,
according to the findings. Up to 120 m and 30 m, respectively, the two and three spatially multiplexed channels in the ...
Photonics
(MDPI)
• 23 Mar 2022
Drljača, Branko • Savović, Svetislav • Kovačević, Milan • Simović, Ana • Kuzmanović, Ljubica • Djordjevich, Alexandar • Min, Rui
Solving the time-dependent power flow equation (PFE) provides a useful method to study
the transmission bandwidth of step-index silica photonic crystal fibers (SI SPCFs). The transmission
bandwidth of these kinds of fibers is determined for different air-hole structures (different numerical apertures (NAs)) and different distribution widths of the Gaussian launch beam. The results
indicate that the lower the NA of SI SPCFs, the higher the bandwidth (for example, for a lower NA
of SI SPCF ...
Optik
(Elsevier)
• 21 Aug 2021
Savović, Svetislav • Kovačević, Milan • Drljača, Branko • Simović, Ana • Kuzmanović, Ljubica • Djordjevich, Alexandar
We investigate the state of mode coupling in a multimode step-index plastic photonic crystal fiber
(SI PPCF) with a solid-core by solving the time-independent power flow equation. For various
arrangements of air-holes, and therefore a different numerical apertures (NAs), as well as a
different widths of launch beam distribution, the length Lc for achieving equilibrium mode distribution (EMD) and length zs at which a steady state distribution (SSD) is established are
determined for such f ...
Optik
(Elsevier)
• 30 Jul 2021
Savović, Svetislav • Kovačević, Milan • Simović, Ana • Kuzmanović, Ljubica • Drljača, Branko • Djordjevich, Alexandar
We propose a new method for investigation the state of mode coupling in a multimode step-index
silica photonic crystal fiber (SI SPCF) with a solid-core by solving the time-independent power
flow equation. For various arrangements of air-holes (different numerical apertures (NAs)), as
well as a different widths of launch beam distribution, the length Lc for achieving equilibrium
mode distribution (EMD) and length zs at which a steady state distribution (SSD) is established are
determin ...
Ricerche di Matematica
(Springer)
• 26 Oct 2021
Savović, Svetislav • Drljača, Branko • Djordjevich, Alexandar
An unconditionally-positive finite difference (UPFD) and the standard explicit finite difference schemes are compared to the analytical solution of the advection–diffusion reaction equation which describes the exponential traveling wave in heat and mass transfer processes. It is found that although the unconditional positivity of the UPFD scheme, this scheme is less accurate than the standard explicit finite difference scheme. This is because the UPFD scheme contains additional truncation-error ...
Optik - International Journal for Light and Electron Optics
(Elsevier)
• 08 Aug 2021
Simović, Ana • Savović, Svetislav • Drljača, Branko • Djordjevich, Alexandar
This paper investigates the wavelength dependence of the equilibrium mode distribution (EMD)
and steady state distribution (SSD) in W-type plastic optical fibers (POFs) with graded index (GI)
core distribution for parametrically varied width of the fiber’s intermediate optical layer and
refractive index of the outer cladding. The numerical solution of the time-independent power flow
equation is used to determine the transmission characteristics of the W-type GI POF. We
demonstrated tha ...
Optical Fiber Technology
(Elsevier)
• 27 Nov 2019
Drljača, Branko • Simović, Ana • Djordjevich, Alexandar • Savović, Svetislav
Wavelength dependence of equilibrium mode distribution (EMD) and steady state distribution (SSD) in W-type
plastic-clad silica fibers (PCSFs) is investigated in this paper for parametrically varied width of the fiber’s intermediate optical layer and refractive index of the outer cladding. We have shown that the W-type PCSF has
better transmission characteristics at longer infrared wavelengths. This is explained by the rise of the leaky mode
losses with increasing wavelength. This facilitates ...
Laser Physics Letters
(IOP Publishing)
• 27 Jun 2019
Simović, Ana • Savović, Svetislav • Drljača, Branko • Djordjevich, Alexandar
A new design of a multimode plastic-clad silica optical fiber that takes the characteristic
W-shaped index profile is proposed. The bandwidth and steady-state loss are determined
for such a W-type plastic-clad silica optical fiber for the different structural parameters of
the fiber. We have shown that the bandwidth of a W-type plastic-clad silica optical fiber is
significantly higher (up to 15 times at a fiber length of 2 km) than the bandwidth of the singly clad step index plastic-clad ...
Electroanalysis
• 01 Apr 2024
Petković, Branka • Ognjanović, Miloš • Antić, Bratislav • Viktorovich Avdin, Vyacheslav • Manojlović, Dragan • Vranješ Đurić, Sanja • Stanković, Dalibor
The homemade, porous carbon material, thermolysis prepared from Novolac phenol-formaldehyde resin, in situ modified with Co3O4 nanoparticles and mixed with single-wall carbon nanotubes, was used in selective sensing of prominent antioxidant α-lipoic acid
(LA). XRD, SEM and EIS measurements were used for characterization of material composition, structure, morphology and improved conductivity. The quantification of LA at TPCo3O4&SWCNTCPE was done by a squarewave voltammetric technique in BR buff ...
Journal of the Science of Food and Agriculture
(Wiley-VHCA AG, Zurich, Switzerland)
• 11 May 2019
Pecev-Marinković, Emilija • Miletić, Ana • Tošić, Snežana • Pavlović, Aleksandra • Kostić, Danijela • Rašić Mišić, Ivana • Dekić, Vidoslav
BACKGROUND: Pesticides are potentially toxic to humans and can produce both acute and chronic health effects, depending on the quantity and the ways in which a person is exposed. Exposure to pesticides can cause serious health problems. Infants and young children are particularly sensitive to these contaminants because their brains and organ systems are not fully developed. For this reason, it is important to determine the quantities of pesticides in baby food.
RESULTS: The aim of this study wa ...
Diamond and Related Materials
• 01 Apr 2024
Jevtić, Sonja • Stefanović, Anđela • Stanković, Dalibor • Pergal, Marija • Ivanović, Aleksandra • Jokić, Anja • Petković, Branka
Bentazone (BZ) is selective contact-past herbicide with suspected reproductive toxicity potential for human due to possible contamination of ground and surface waters. This work presents simple, rapid, sensitive and accurate determination of bentazone at unmodified boron-doped diamond electrode, using differential pulse voltammetry in Britton-Robinson buffer (pH 4, oxidation peak at 1.0 V). Under optimized DPV conditions linear calibration
curve was obtained for range of 2 to 100 μM, with a det ...
Water, Air, and Soil Pollution
• 01 Apr 2024
Pergal, Marija • Kodranov, Igor • Pergal, Miodrag • Dojčinović, Biljana • Stanković, Dalibor • Petković, Branka • Manojlović, Dragan
The degradation of two sulfonylurea herbicides, nicosulfuron and thifensulfuron methyl in water by chlorine dioxide, was studied for the first time in this paper. In order to examine the optimal parameters for degradation of both herbicides, degradation was investigated under light or dark conditions with different amount of chlorine dioxide, different degradation periods, and at different pH values. Degradation efficiency of herbicides was monitored using high-performance liquid chromatography ...
Water Air Soil Pollut
• 01 Apr 2024
Pergal, Marija • Kodranov, Igor • Pergal, Miodrag • Gašić, Uroš • Stanković, Dalibor • Petković, Branka • Manojlović, Dragan
The aim of this study was to investigate, analyze, and compare applied techniques suitable for achieving efficient removal of organophosphorus pesticides (OPPs) (malathion and fenitrothion) from aqueous solutions and analyze the degradation products and processes. Pesticide degradation efficiency (%) was monitored by highperformance liquid chromatography (HPLC) equipped with a photodiode array detector (DAD), while mineralization degree was determined by total organic carbon analysis (TOC). Daph ...
Diamond and Related Materials
• 01 Apr 2024
Petković, Branka • Ognjanović, Miloš • Krstić, Milena • Stanković, Vesna • Babincev, Ljiljana • Pergal, Marija • Stanković, Dalibor
Mefenamic acid and indomethacin, medicaments belonging to the group of non-steroidal anti-inflammatory agents, were determined separately and simultaneously at anodically prepared BDDE. Differential pulse voltammetry was used to establish simple and fast analytical procedure based on electrooxidation of mefenamic acid at 0.6 V and indomethacin at 1.0 V (and 1.1 V). At optimal conditions, it was suitable for highly sensitive
and selective determination of these compounds with LODs comparable to ...
Entropy
(Molecular Diversity Preservation International)
• 22 Jul 2021
Perić, Zoran • Savić, Milan • Simić, Nikola • Denić, Bojan • Despotović, Vladimir
Achieving real-time inference is one of the major issues in contemporary neural network applications, as complex algorithms are frequently being deployed to mobile devices that have constrained storage and computing power. Moving from a full-precision neural network model to a lower representation by applying quantization techniques is a popular approach to facilitate this issue. Here, we analyze in detail and design a 2-bit uniform quantization model for Laplacian source due to its significance ...
Entropy
(Molecular Diversity Preservation International)
• 16 Mar 2022
Simić, Nikola • Suzić, Siniša • Nosek, Tijana • Vujović, Mia • Perić, Zoran • Savić, Milan • Delić, Vlado
Speaker recognition is an important classification task, which can be solved using several
approaches. Although building a speaker recognition model on a closed set of speakers under neutral speaking conditions is a well-researched task and there are solutions that provide excellent performance, the classification accuracy of developed models significantly decreases when applying them to emotional speech or in the presence of interference. Furthermore, deep models may require a large number of ...
Phytochemical Analysis
(Wiley-VHCA AG, Zurich, Switzerland)
• 10 Dec 2019
Radulović, Niko • Mladenović, Marko • Ristić, Milenko • Dekić, Vidoslav • Dekić, Biljana • Ristić, Novica
Introduction: Minor plant constituents are difficult to identify due to the challenging
isolation and acquiring of reliable spectral data. Essential oils abound in such minor
constituents that might be of high importance for their (e.g. olfactory) properties. The
presence of new minor constituents is usually inferred from gas chromatography
mass spectrometry (GC-MS) analyses that provide only a mass spectrum and retention
data, which are insufficient to allow a positive identification.
Obj ...
Chemistry & Biodiversity
• 25 Oct 2018
Ristić, Milenko • Radulović, Niko • Dekić, Biljana • Dekić, Vidoslav • Ristić, Novica • Stojanović-Radić, Zorica
Nine unsymmetrical azines containing a coumarin moiety were prepared by the reaction of the hydrazone of 4-hydroxy-3-acetylcoumarin with differently substituted aromatic aldehydes. The azines were fully spectrally characterized, including a complete assignment of 1H- and 13C-NMR resonances, and were assessed for their acute toxicities in the Artemia salina model. Their free radical scavenging activities were tested in the DPPH assay, and in vitro antimicrobial activities were determined against ...
Filomat
(Faculty of Sciences and Mathematics, University of Niš)
• 01 Jan 2019
Rančić, Svetozar • Najdanović, Marija • Velimirović, Ljubica
In this paper we consider first order infinitesimal bending of curves and knots. The total
normalcy of the knot during the first order infinitesimal bending is discussed and expressions for the first variation of the total normalcy are given. Some examples aimed to illustrate infinitesimal bending of knots are shown using figures. Colors are used to illustrate normalcy values at dierent points of bent knots and the total normalcy is numerically calculated.
Symmetry
(MDPI (Basel, Switzerland))
• 07 Apr 2019
Patle, Pradip • Vujaković, Jelena • Patel, Deepesh • Radenović, Stojan
A new proper generalization of metric called as θ -metric is introduced by Khojasteh et al. (Mathematical Problems in Engineering (2013) Article ID 504609). In this paper, first we prove the Caristi type fixed point theorem in an alternative and comparatively new way in the context of θ -metric. We also investigate two θ -metrics on CB(X) (family of nonempty closed and bounded subsets of a set X). Furthermore, using the obtained θ -metrics on CB(X) , we prove two new fixed point results for mult ...
Open Mathematics
(De Gruyter Open Access)
• 09 Aug 2019
George, Reny • Nabwey, Hossam A. • Vujaković, Jelena • Ramaswamy, Rajagopalan • Vinayakam, Selva
In this paper we introduce dislocated and dislocated quasi version of a cone b-metric space over a Banach algebra as well as weak semi α-admissible and α-identical pair of mappings and prove common fixed point theorems for a pair of α-identical and weak α-admissible mappings in the aforesaid spaces. Our results are supported with suitable examples and an application to a system of m-tupled functional equations.
Symmetry
(MDPI (Basel, Switzerland))
• 10 Dec 2020
Vujaković, Jelena • Ljajko, Eugen • Radojević, Slobodan • Radenović, Stojan
Many authors used the concept of F−contraction introduced by Wardowski in 2012 in order to define and prove new results on fixed points in complete metric spaces. In some later papers (for example Proinov P.D., J. Fixed Point Theory Appl. (2020)22:21, doi:10.1007/s11784-020-0756-1) it is shown that conditions (F2) and (F3) are not necessary to prove Wardowski’s results. In this article we use a new approach in proving that the Picard–Jungck sequence is a Cauchy one. It helps us obtain new Jungck ...
Environmental Science and Pollution Research
(Springer)
• 01 Apr 2024
Gulan, Ljiljana • Stajic, Jelena M. • Milenkovic, Biljana • Zeremski, Tijana • Milic, Stanko • Krstic, Dragana
In most European countries, each adult citizen drinks on averagemore than 20 L of wine every year. Three popular wine-growing areas (Aleksandrovac, Topola, and Orahovac) in Serbia were studied in order to investigate the abundance and uptake of elements from vineyard soil to plants. The specific activities of radionuclides (226Ra, 232Th, 40K, 137Cs, and 7Be) were measured in soil, leaves, and grape berries. 226Ra and 232Th were positively correlated with silt and clay and negatively correlated w ...
Journal of Radioanalytical and Nuclear Chemistry
(Springer)
• 01 Apr 2024
Gulan, Ljiljana • Jakšić, Tatjana • Milenkovic, Biljana • Stajic, Jelena M. • Vasić, Predrag • Simić, Zoran
The study investigates mosses (Hypnum cupressiforme Hedw.) as bioindicators of pollution in three non-urban mountain areas of northern Kosovo and Metohija regions. Concentrations of radionuclides and metals were measured in moss and soil samples. 137Cs specific activities in soil were strongly correlated with organic matter content. 137Cs in mosses was
significantly higher in coniferous than in deciduous forests. 7Be measured in moss samples was increasing with altitude. Concentrations of Ni, C ...
Journal of Radioanalytical and Nuclear Chemistry
(Springer)
• 17 May 2018
Gulan, Ljiljana • Valjarević, Aleksandar • Milenković, Biljana • Stevanović, Vladica • Milić, Gordana • Stajić, Jelena M.
This study was performed in order to investigate gamma dose rates, radon exhalation rates and soil radioactivity with respect to geology. Fifteen locations in three Serbian spas were under investigation. Gamma dose rate was measured by Radex RD1503? monitor. GIS technology was applied for the interpretation of the results. HPGe detector was used for
gamma-spectrometry determination of soil radioactivity. Radon exhalation rate was determined using RAD7 device. The correlation was examined betwee ...
Laser Physics
(IOP Science)
• 07 Jan 2020
Drljača, Branko • Simović, Ana • Djordjevich, Alexandar • Savović, Svetislav
The bandwidth and steady-state loss of multimode W-type plastic-clad silica optical fibers are
investigated by solving the time-dependent power flow equation. The results show how the
bandwidth of W-type plastic-clad silica optical fibers can be enhanced by shifting from the red
to the infrared wavelength region for different intermediate layer widths and refractive indices
of the outer cladding. Such characterization of these fibers is consistent with their manifest
effectiveness in reduci ...
Laser Physics
(IOP Science)
• 27 May 2020
Drljača, Branko • Simović, Ana • Djordjevich, Alexandar • Savović, Svetislav
Wavelength dependence of equilibrium mode distribution (EMD) and steady state distribution
(SSD) in W-type plastic optical fibers (POFs) is investigated in this paper for parametrically
varied width of the fiber’s intermediate optical layer and refractive index of the outer cladding.
We have shown that with increasing the wavelength EMD and SSD are achieved at shorter
W-type POF lengths. This is explained by the rise of the leaky mode losses with increasing
wavelength. This facilitates tail ...
Laser Physics
(IOP Science)
• 28 Jul 2020
Savović, Svetislav • Djordjevich, Alexandar • Simović, Ana • Drljača, Branko
We propose a spatial division multiplexing in a new designed multimode multicore graded index
plastic optical fiber with nine cores arranged in an octagonal array. The influence of mode
coupling on two-channel spatial division multiplexing capability in each of nine cores is
investigated by solving the power flow equation. Our numerical results show that mode coupling
significantly limits the fiber length at which the spatial division multiplexing can be realized in
each of nine cores with ...
Laser Physics
(IOP Science)
• 27 Oct 2020
Svetislav, Savović • Djordjevich, Alexandar • Simović, Ana • Drljača, Branko
The influence of mode coupling on three-channel spatial division multiplexing capability in
multimode graded index plastic optical fibers is investigated by solving the power flow
equation. Our numerical results show that mode coupling significantly limits the fiber length at
which the spatial division multiplexing can be realized with a minimal crosstalk between three
neighbor spatial optical channels. Three spatial channels in the multimode graded index plastic
optical fiber can be employ ...
Journal of Russian Laser Research
(Springer Link)
• 03 Jul 2021
Drljača, Branko • Simović, Ana • Djordjevich, Alexandar • Savović, Svetislav
We investigate the bandwidth and steady-state losses of multimode W-type plastic optical fibers solving the time-dependent power flow equation and show how the bandwidth in W-type plastic optical
fibers can be enhanced by increasing the wavelength for different widths of the intermediate layer
and refractive indices of the outer cladding. Such characterization of the fibers is consistent with
their manifested efficiency in reducing modal dispersion and increasing bandwidth; this fact facilita ...
Laser Physics
(IOP Science)
• 16 Jul 2021
Drljača, Branko • Simović, Ana • Djordjevich, Alexandar • Min, Rui • Jovanović, Slavica • Savović, Svetislav
We show strong effects of width of the launch beam’s angular distribution on bandwidth and
mode coupling in W-type plastic optical fibers (POFs). In general, the broader this width, the
stronger the coupling and the lower the bandwidth—but the bandwidth drop due to this effect
tapers off with distance from the input end and ceases at lengths over 25 m as the steady state
distribution is reached. With increasing the strength of mode coupling, the equilibrium mode
distribution is reached at s ...
Optics Communications
(Elsevier)
• 13 Mar 2018
Djordjevich, Alexandar • Simović, Ana • Savović, Svetislav • Drljača, Branko
Infrared wavelength dependence of leaky mode losses and steady state distribution
(SSD) in W-type glass optical fibers (doubly clad fibers with three layers) is
investigated in this paper for parametrically varied depths and widths of the fiber’s
intermediate optical layer. This enables a tailoring of configuration of the W-type
fiber to suit an application at hand. We have shown that the proposed W-type fiber
has better transmission characteristics at longer infrared wavelengths.
Optics Communications
(Elsevier)
• 30 Jun 2018
Kovačević, Milan • Kuzmanović, Ljubica • Simović, Ana • Savović, Svetislav • Drljača, Branko • Djordjevich, Alexandar
A multimode photonic crystal fiber with a solid-core takes the characteristic W-shaped index profile upon forming
an inner cladding layer with its own value of the effective refractive index corresponding to the distinct size
and/or spacing of air holes in it. For various arrangements of air-holes, bandwidth is determined for such fiber
by the time-dependent power flow equation. Fiber bandwidth is thus not only a function of transmission length
but also of the spacing and size of air-holes a ...
Optical Fiber Technology
(Elsevier)
• 28 Aug 2018
Simović, Ana • Savović, Svetislav • Drljača, Branko • Djordjevich, Alexandar
Transmission characteristics (bandwidth and steady state loss) of multimode W-type glass optical fibers are investigated by solving the time-dependent power flow equation. Results show how the bandwidth in W-type glass optical fibers can be enhanced by shifting from the red to infrared wavelength region for different depths and widths of the intermediate layer as well as for different launch excitations. Such characterization of these fibers is consistent with their manifested effectiveness in r ...
International Journal of Adhesion and Adhesives
(Elsevier)
• 15 Jun 2022
Samaržija-Jovanović, Suzana • Jovanović, Vojislav • Jovanović, Tijana • Kostić, Marija • Petković, Branka • Marković, Gordana • Porobić, Slavica • Papan, Jelena • Marinović-Cincović, Milena
Urea-formaldehyde (UF) composites with a formaldehyde/urea (FA/U) ratio = 0.8 and different particle sizes of montmorillonite (MMT), namely UF/KSF and UF/K10 were synthesized. The hydrolytic stability of modified UF composites was determined by measuring the content of the liberated formaldehyde of modified UF composites after acid hydrolysis. The synthesized modified UF composites were irradiated (50 kGy) and the effect of γ–irradiation was evaluated on the basis of these thermal behaviors. The ...
Polymer Bulletin
(Springer Nature)
• 25 Jan 2021
Jovanović, Vojislav • Samaržija-Jovanović, Suzana • Petković, Branka • Jovanović, Slaviša • Marković, Gordana • Porobić, Slavica • Marinović-Cincović, Milena
The hydrolytic stability of two nano-SiO2-based UF composites with derivates of coumarin (names as K-1 and K-2) was investigated. K-1 is 3-nitro-4-(p-tolylamino)-2H-chromen-2-one and K-2: 4-((3-nitro-2-oxo-2H-chromen-4-yl)amino)benzenesulfonamide. Two types of nano-silica-based urea–formaldehyde (UF), composite materials with a formaldehyde-to-urea (F/U) ratio of 0.8, were synthesized (UF/K-1/SiO2, and UF/K-2/SiO2). The hydrolytic stability of modified UF composite was determined by measuring th ...
Polymer Composites
(Wiley)
• 16 Sep 2020
Samaržija-Jovanović, Suzana • Jovanović, Vojislav • Petković, Branka • Jovanović, Tijana • Marković, Gordana • Porobić, Slavica • Papan, Jelena • Marinović-Cincović, Milena
Urea-formaldehyde resin (F/U ratio of 0.8)/thermally activated montmorillonite (UF/ΔTK10) nanocomposite was synthesized. The hydrolytical, thermal, and UV radiation stability of UF/ΔTK10 nanocomposites are determined. UF hybrid nanocomposites have been irradiated with UV light with a wavelength of 254 nm and 366 nm, and after that, their radiation stability was evaluated. The free formaldehyde (FA) percentage in all prepared samples was determined. The sample was characterized by using X-ray dif ...
Polymer Composites
(Wiley)
• 15 Aug 2019
Porobić, Slavica • Marković, Gordana • Ristić, Ivan • Samaržija-Jovanović, Suzana • Jovanović, Vojislav • Budinski-Simendić, Jaroslava • Marinović-Cincović, Milena
In this applicative work, two types of silica filler were used to increase the adhesion strength between steel and elastomeric hybrid materials based on chlorosulfonated polyethylene rubber (CSM) and polychloroprene rubber (CR) as network precursors. Precipitated silica (PS) with the average size of primary particles 15 nm and diatomaceous earth (DE) with the average size of primary particles 28 μm were used to ascertain differences in metal-elastomer compounds adhesion strength caused by differ ...
Polymer Composites
(Wiley)
• 10 Apr 2019
Jovanović, Vojislav • Jovanović, Slaviša • Marković, Gordana • Samaržija-Jovanović, Suzana • Porobić, Slavica • Budinski-Simendić, Jaroslava • Marinović-Cincović, Milena
The powder recycled rubber (PRR) can be used as a filler and a modifier for elastomeric materials and asphalt. Composites based on elastomers and recycled rubber powders are a serious challenge for the environment. The main goal of this paper was to study the effect of rubber powder on the mechanical properties of elastomeric composites based on three precursors of the network. Triple blends were prepared using non-polar natural rubber (NR), polyisoprene rubber (BR), and styrene-butadiene rubber ...
Polymer Composites
(Wiley)
• 10 Apr 2019
Jovanović, Vojislav • Samaržija-Jovanović, Suzana • Petković, Branka • Milićević, Zoran • Marković, Gordana • Marinović-Cincović, Milena
Two biocomposites based on cellulose (UFC) and starch modified urea formaldehyde (UFS) resin (F/U ratio of 0.8) were synthesized using the same procedure. The hydrolitical, thermal, and radiation stability of biocomposites are determined. Also, released formaldehyde during the acid hydrolysis is determined. Biocomposites based on modified UF resin have been irradiated with (50 kGy). Cellulose modified UF resin after γ-radiation has 1.38% released formaldehyde; unmodified UF resin has 2.21% relea ...
Journal of Thermoplastic Composite Materials
(SAGE)
• 24 Feb 2018
Jovanović, Slaviša • Samaržija-Jovanović, Suzana • Marković, Gordana • Jovanović, Vojislav • Adamović, Tijana • Marinović-Cincović, Milena
The goal of this work was to synthesize and characterize ternary rubber blends based on polyisoprene (natural rubber (NR)), polybutadiene rubber (BR), and styrene–butadiene rubber (SBR) (NR/BR/SBR = 25/25/50) reinforced with different loading silica (SiO2) nanoparticles (0–100 part per hundred parts of rubber (phr)). The specimens were subjected to thermooxidative aging at 100°C, for two times: at 72 and 168 h, respectively, and then mechanically stretched to fracture by tension with a Zwick 142 ...
Axioms
(MDPI)
• 20 May 2021
Kontrec, Nataša • Panić, Stefan • Panić, Biljana • Marković, Aleksandar • Stošović, Dejan
Reliability, the number of spare parts and repair time have a great impact on system availability. In this paper, we observed a repairable system comprised of several components. The aim was to determine the repair rate by emphasizing its stochastic nature. A model for the statistical analysis of the component repair rate in function of the desired level of availability is presented. Furthermore, based on the presented model, the approach for the calculation of probability density functions of m ...
Eksploatacja i Niezawodność - Maintenance and Reliability
(Polish Maintanace Society)
• 01 Sep 2018
Kontrec, Nataša • Panić, Stefan • Petrović, Milena • Milošević, Hranislav
Performance Based Logistics (PBL) concept has an aim to improve the system availability and it has been extensively researched in the recent years. These researches showed that inventory level does not impact system availability as much as component reliability and repair time in repairable system operating under PBL contract. Based on that, in this paper, we propose a new stochastic model for determination of annual repair rate for critical aircraft components in such system in order to achieve ...
SYMMETRY-BASEL
(MDPI)
• 08 Dec 2021
Kontrec, Nataša • Vujaković, Jelena • Tošić, Marina • Panić, Stefan • Panić, Biljana
The repair rate is a very important parameter for system maintainability and can be defined as a frequency of successfully performed repair actions on a failed component per unit of time. This paper analyzes the integral characteristics of a stochastic repair rate for corresponding values of availability in a system operating under maintenance contracts. The probability density function (PDF) of the repair rate has been studied extensively and it was concluded that it is not a symmetric function ...
Symmetry
(MDPI)
• 05 Sep 2020
Panić, Biljana • Kontrec, Nataša • Vujošević, Mirko • Panić, Stefan
In this paper, a stochastic problem of multicenter location on a graph was formulated through the modification of the existing p-center problem to determine the location of a given number of facilities, to maximize the reliability of supplying the system. The system is represented by a graph whose nodes are the locations of demand and the potential facilities, while the weights of the arcs represent the reliability, i.e., the probability that an appropriate branch is available. First, k location ...
IET COMMUNICATIONS
• 01 Apr 2024
Smilić, Marko • Nikolić, Zorica • Milić, Dejan • Spalević, Petar • Panić, Stefan
In this study, the authors investigate average capacity of free space optics communication over Málaga atmospheric turbulence channel with pointing errors and path loss, for intensity modulated/direct detection (IM/DD) and heterodyne detection. Various algorithms which use adaptive transmission with both types of detection are considered, such as: optimal rate adaption (ORA), optimal power and rate adaption (OPRA), channel inversion with fixed rate (CIFR) and truncated channel inversion with fix ...
MATHEMATICAL PROBLEMS IN ENGINEERING
• 01 Apr 2024
Milovanović, Gradimir • Suljović, Suad • Panić, Stefan • Kalčo, Ismet • Stefanović, Mihajlo
We will provide statistical analysis of the square ratio of and random processes and its application in the signal-to-interference ratio (SIR) based performance analysis of wireless transmission subjected to the influence of multipath fading, modelled by fading model, and undesired occurrence of co-channel interference (CCI), distributed as random process. First contribution of the paper is deriving exact closed expressions for the probability density function (PDF) and cumulative distribution f ...
TURKISH JOURNAL OF MATHEMATICS
(Scientific and Technical Research Council of Turkey - TUBITAK^(Turkiye Bilimsel ve Teknik Arastirma Kurumu))
• 21 Jan 2021
Maksimović, Miroslav • Velimirović, Ljubica • Najdanović, Marija
The mathematics of DNA molecules is often studied as a double helix model. This paper focuses on the modelling of infinitesimal bending of DNA helices. The paper checks the flexibility of DNA molecule, i.e. the flexibility of double helix in infinitesimal bending theory. Actually, first, we find infinitesimal bending field of an arbitrary curve on the helicoid, that leaves bent curves on the helicoid, and show that helix bending on the helicoid is not possible. Finally, we deal with the infinite ...
Turkish Journal of Mathematics
• 01 Apr 2024
Maksimović, Miroslav • Stanković, Mića
The purpose of this paper is to investigate the product semisymmetric connection in a locally decomposable Riemannian space. The curvature tensors of this connection were considered. Some properties of almost product structure, some properties of torsion tensor of product semisymmetric connection and some relations between curvature tensors and almost product structure are given. Also, the paper checks a special case of such connection when its generator is a gradient vector.
