Journal of Contemporary Mathematical Analysis
(Armenian Academy of Sciences)
• 21 Nov 2021
Valjarević, Dragana • Petrović, Ljiljana
In this paper we consider the concept of statistical causality in continuous time between
filtrations associated with stopping times, which is based on Granger’s definition of causality.
Especially, we consider a generalization of a causality relationship “His a cause of E within F” from
fixed to stopping time. Then we apply the given concept of causality to strongly orthogonal stopped
martingales. We show the equivalence between the given concept of causality and orthogonality of
stopped l ...
Land Use Policy
(Elsevier Ltd.)
• 21 Sep 2019
Ristić, Dušan • Vukoičić, Danijela • Milinčić, Miroljub
With the formulation of tourism development strategies for the social and economic development of an area, rural tourism moved to a more complex phase of development. Numerous empirical studies have shown that different forms of rural tourism can have positive and negative effects on the natural and socio-economic context in the area where they are present. There are several methodologies for assessing the development of tourism in rural areas. One of the efficient and commonly used tools in pre ...
Optics Express
(Optica Publishing Group (Formerly OSA))
• 23 Jun 2022
Drljača, Branko • Savović, Svetislav • Kovačević, Milan • Simović, Ana • Kuzmanović, Ljubica • Djordjevich, Alexandar • Min, Rui
By solving the time-independent power flow equation (TI PFE), we study mode coupling in a multimode W-type microstructured polymer optical fiber (mPOF) with a solid-core. The multimode W-type mPOF is created by modifying the cladding layer and reducing the core of a multimode singly clad (SC) mPOF. For such optical fiber, the angular power distributions, the length Lc at which an equilibrium mode distribution (EMD) is achieved, and the length zs for establishing a steady state distribution (SSD) ...
Frontiers in Physics
(Frontiers)
• 25 May 2022
Savović, Svetislav • Djordjevich, Alexandar • Drljača, Branko • Simović, Ana • Min, Rui
Using the power flow equation (PFE), this article investigates mode coupling in step-index
(SI) multimode (MM) polymer optical fiber (POF). This equation’s coupling coefficient was
initially fine-tuned so that it could appropriately reconstruct previously recorded far-field
(FF) power distributions. The equilibrium mode distribution (EMD) and steady-state
distribution (SSD) in the SI MM POF were found to be obtained at lengths Lc = 15 m
and zs = 41 m, respectively. These lengths are substan ...
Polymers
(MDPI)
• 01 Dec 2021
Drljača, Branko • Savović, Svetislav • Kovačević, Milan • Simović, Ana • Kuzmanović, Ljubica • Djordjevich, Alexandar • Min, Rui
By solving the time-dependent power flow equation, we present a novel approach for evaluating the bandwidth in a multimode step-index polymer photonic crystal fiber (SI PPCF) with a solid core. The bandwidth of such fiber is determined for various layouts of air holes and widths of Gaussian launch beam distribution. We found that the lower the NA of SI PPCF, the larger the bandwidth. The smaller launch beam leads to a higher bandwidth for short fibers. The influence of the width of the launch be ...
Polymers
(MDPI)
• 17 Nov 2021
Simović, Ana • Savović, Svetislav • Drljača, Branko • Alexandar, Djordjevich • Min, Rui
The bandwidth of multimode W-type plastic optical fibers (POFs) with graded-index (GI) core distribution is investigated by solving the time-dependent power flow equation. The multimode W-type GI POF is designed from a multimode single-clad (SC) GI POF fiber upon modification of the cladding layer of the latter. Results show how the bandwidth in W-type GI POFs can be enhanced by increasing the wavelength for different widths of the intermediate layer and refractive indices of the outer cladding. ...
Optics Express
(Optica Publishing Group)
• 13 Sep 2021
Simović, Ana • Drljača, Branko • Savović, Svetislav • Djordjevich, Alexandar • Min, Rui
A new method is proposed for investigating the bandwidth in multimode graded-index
plastic optical fibers (GI POFs). By numerically solving the time-dependent power flow equation,
bandwidth is reported for a varied launch conditions (radial offsets) of multimode GI POF. Our
theoretical results are supported by the experimental results which show that bandwidth decreases
with increasing radial offset. This decrease is more pronounced at short fiber lengths. At fiber
length close to the coupl ...
Optics and Laser Technology
(Elsevier)
• 11 Jun 2021
Simović, Ana • Djordjevich, Alexandar • Drljača, Branko • Savović, Svetislav
A method is proposed for investigation of transmission along a multimode W-type (doubly clad) plastic optical fiber (POF) with graded index (GI) distribution of the core. The multimode W-type GI POF is designed from a multimode singly clad (SC) GI POF fiber upon modification of the cladding layer of the latter. The transmission characteristics of such proposed W-type GI POF are determined from the numerical solution of the power flow equation. We have shown that coupling length Lc at which an eq ...
Numerical Algorithms
(Springer)
• 03 Dec 2019
Petrović, Milena • Rakočević, Vladimir • Valjarević, Dragana • Ilić, Dejan
We introduce a hybrid gradient model for solving unconstrained optimization problems based on one specific accelerated gradient iteration. Having applied a three term hybridization relation on transformed accelerated double step size model, we develop an efficient hybrid accelerated scheme. We determine an iterative step size variable using Backtracking line search technique in which we take an optimally calculated starting value for the posed method. In convergence analysis, we show that the pr ...
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.
Statistic and Probability Letters
(Science direct)
• 21 Jul 2021
Valjarević, Dragana • Merkle, Ana
In this paper we consider a concept of statistical causality, based on Granger’s definition
of causality and analyze the relationships between given causality and the concept
of measurable separability of σ-algebras. The measurable separability of σ-algebras is
defined in Florens et al. (1990). We give a generalization of that definition for flows
of information represented by filtrations and consider some properties of measurable
separability that are directly connected to the concept of s ...
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 ...
Stochastics: An International Journal of Probability and Stochastic Processes
(Taylor and Francis)
• 21 Jul 2018
Petrović, Ljiljana • Valjarević, Dragana
The paper considers a statistical concept of causality in continuous
time in the filtered probability spaces which is based on the Granger’s
definition of causality. The given causality concept is then applied to
the solution of the martingale problem (associated with the stochastic
differential equation driven with semimartingales). More precisely,
we show that the given causality concept is closely connected to
the concept of extremality of measures for the solutions of the
martingale p ...
Stochastics: An International Journal of Probability and Stochastic Processes
(Taylor and Francis)
• 21 Jul 2021
Valjarević, Dragana • Petrović, Ljiljana
The statistical concept of causality in continuous time between
filtered probability spaces considered in this paper is based on
Granger’s definition of causality. The given concept of causality can
be connected to the purely discontinuous property for martingale
and filtration. If M is a purely discontinuous local martingale with
respect to purely discontinuous filtration (Gt), we prove that M will
remain purely discontinuous local martingale with respect to an
extension (Ft) of the filt ...
Statistic and Probability Letters
(Science Direct)
• 21 Nov 2020
Valjarević, Dragana • Petrović, Ljiljana
In this paper we consider the statistical concept for continuous-time stochastic processes,
which is based on Granger’s definition of causality. We, also, show that separability
is directly related to causality concepts. More precisely, we provide necessary
conditions, in terms of statistical causality, for the space Lp(Ω, G∞, P) to be separable.
The concept of statistical causality is related to the notion separability of stochastic
processes, too.
Bulletin of Korean Mathematical Society
• 21 Oct 2018
Petrović, Ljiljana • Valjarević, Dragana
In this paper we consider the concept of statistical causality
in continuous time between
ows of information, represented by ltra-
tions. Then we relate the given concept of causality to the equivalent
change of measure that plays an important role in mathematical nance.
We give necessary and sucient conditions, in terms of statistical causali-
ty, for extremality of measure in the set of martingale measures. Also, we
have considered the extremality of measure which involves the stopping ...
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 ...
Bulletin of the Australian Mathematical Society
(Cambridge University Press)
• 01 Aug 2018
Panić, Stefan • Petrović, Milena • Mihajlov Carević, Miroslava
We improve the convergence properties of the iterative scheme for solving unconstrained optimisation problems introduced in Petrovic et al. [‘Hybridization of accelerated gradient descent method’, Numer. Algorithms (2017), doi:10.1007/s11075-017-0460-4] by optimising the value of the initial step length parameter in the backtracking line search procedure. We prove the validity of the algorithm and illustrate its advantages by numerical experiments and comparisons.
Mathematical Problems in Engineering
(Hindawi)
• 14 Apr 2020
Mihajlov Carević, Miroslava • Petrović, Milena • Denić, Nebojša
In this paper, we are going to demonstrate a method for determining the generating functions of tetrahedral, hexahedral, octahedral, dodecahedral, and icosahedral figurative numbers. The method is based on the differences between the members of the series of the mentioned figurative numbers, as well as on the previously specified generating functions for the sequence and geometric sequence.
EURASIA, Journal of Mathematics, Science and Technology Education
(Modestum)
• 27 Jan 2019
Mihajlov Carević, Miroslava • Petrović, Milena • Denić, Nebojša
Contemporary mathematics teaching is mostly reduced to the application of algebraic
formulas and algebraic procedures. The visual-logical approach in solving
mathematical tasks is very little represented in teaching mathematics. Such practice
should be changed since visualization is of great importance in the process of learning
and understanding mathematics as well as in solving mathematical tasks. This paper
suggests the possibility of developing students’ ability to perceive lawfulness a ...
Applied Surface Science
(Elsevier)
• 25 Oct 2017
Ralević, Uroš • Isić, Goran • Vasić-Anićijević, Dragana • Laban, Bojana • Bogdanović, Una • Lazović, Vladimir • Vodnik, Vesna • Gajić, Radoš
The adsorption of thiacyanine dye molecules on citrate-stabilized silver nanoparticle clusters drop-cast onto freshly cleaved mica or highly oriented pyrolytic graphite surfaces is examined using colocalized surface-enhanced Raman spectroscopy and atomic force microscopy. The incidence of dye Raman sig-natures in photoluminescence hotspots identified around nanoparticle clusters is considered for both citrate- and borate- capped silver nanoparticles and found to be substantially lower in the for ...
Journal of Inorganic Biochemistry
(Elsevier)
• 11 Dec 2019
Laban, Bojana • Ralević, Uroš • Petrović, Suzana • Leskovac, Andreja • Vasić-Anićijević, Dragana • Marković, Mirjana • Vasić, Vesna
The simple green method for synthesis of stable L-Methionine (L-Met) capped silver (Ag@LM NPs) and gold (Au@LM NPs) nanoparticles (NPs) without adding any additional reduction agent or stabilizer was developed. Colloidal dispersions were characterized by UV–Vis spectrophotometry. The size and spherical shape of NPs were evaluated by transmission electron microscopy. Their surface covering was confirmed by atomic force
microscopy, Fourier transform infrared spectroscopy, dynamic light scattering ...
International Journal of Molecular Sciences
(MDPI)
• 11 Aug 2022
Bondžić, Aleksandra • Jovanović, Dunja • Arsenijević, Nevena • Laban, Bojana • Lazarević-Pašti, Tamara • Klekota, Urszula • Bondžić, Bojan
The study of the interactions between nanoparticles (NPs) and proteins has had a pivotal
role in facilitating the understanding of biological effects and safe application of NPs after exposure to the physiological environment. Herein, for the first time, the interaction between L-methionine capped silver nanoparticles (AgMet), and bovine serum albumin (BSA) is investigated in order to predict the fate of AgMet after its contact with the most abundant blood transport protein. The detailed insigh ...
ChemistrySelect
(Wiley-VCH GmbH)
• 08 Sep 2020
Veljović, Đorđe • Gurešić, Dejan • Jokić, Anja • Vasić, Vesna • Laban, Bojana
The silver nanoparticles (Ag NPs) were successfully synthesized by a facile solid-state chemical method. Ag NPs were obtained by a mechanochemical reaction between silver nitrate and sodium citrate, with the constant stirring and heating of reactants. The size and morphology characterization of NPs powder was performed by scanning electron microscopy. The obtained NPs were spherical with a 36 nm average particle size diameter. UV-Vis spectroscopy, dynamic light scattering, and zeta potential mea ...
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.
Mediterranean Journal of Mathematics
• 01 Apr 2024
Maksimović, Miroslav • Zlatanović, Milan
By using decomposition of curvature tensors of generalized Riemannian space in the Eisenhart sense, the Einstein type curvature tensors and Einstein type tensors of that space are determined and defined. All these tensors vanish if the corresponding Ricci tensors also
vanish in the observed space. All these tensors are traceless tensors and their properties of symmetry and anti-symmetry were examined. We proved that the Einstein type curvature tensors of the second kind, of the fourth kind and o ...
Technium
(Proceedings of the 7th Technium Conference 2020)
• 15 Sep 2020
Mihajlov Carević, Miroslava • Ilić, Miloš • Petrović, Milena • Denić, Nebojša
In this paper we deal with a method for the determination of numbers in a Pascal triangle that are simultaneously triangular, tetrahedral and pentaedroidni.
The collected results, obtained by mathematical analysis, were verified by computer. For this purpose, we used the C# programming language as well as the computer laboratory within our University in order to test the results. The results collected by computer confirmed the accuracy of the results obtained by mathematical analysis.
Technium: Proceedings of Fair Transport and Gender Academic Conference
(Technium)
• 15 Jun 2020
Mihajlov Carević, Miroslava • Petrović, Milena • Denić, Nebojša • Mitrović, Aleksandra
One of the main tasks in teaching mathematics is to develop students’ constructive thinking. In order to effectively accomplish this task, it is necessary to make a good selection of instructional materials and teaching aids. In order to make good selection and improve the teaching of mathematics, it is, also, necessary to include a statistical analysis of the certain factors’ impact that affect mathematics curriculum. For the purpose of this research, we used the software computational approach ...
Computer Applications in Engineering Education
(Wiley)
• 07 May 2020
Zlatković, Dragan • Denić, Nebojša • Petrović, Milena • Ilić, Miloš
E‐learning, as a complex system, includes distance learning, teaching materials in various forms and shapes, group and individual learning processes, as well as interactive and tutorial work. To increase the effectiveness and efficiency of the e‐learning system, it is necessary first of all to consider the characteristics of students and their learning styles. Based on the data collected in various ways, in surveys, using the distance learning dystem (DLS) Moodle, based on the subjective assessm ...
Ekonomski izazovi
• 20 Jul 2020
Mihajlov Carević, Miroslava • Petrović, Milena • Denić, Nebojša
Poslednjih godina je uočljiva povećana primena informaciono-komunikacionih tehnologija i matematičkog softvera u nastavi matematike. Mnogobrojna istraživanja efikasnosti matematičkog učenja su pokazala opravdanost i korisnost implementacije novih nastavnih sredstava. Takođe su pokazala da učenje uz obrazovni softver ima veliki uticaj na postignuće učenika u ukupnom sticanju matematičkog znanja tokom nastavne godine kao i na završnom ispitu na kraju osnovnog obrazovanja. Nastava realizovana prime ...
(4th International Scientific Conference – EMAN 2020 – Economics and Management: How to Cope With Disrupted Times, Online/Virtual, September 3, 2020, SELECTED PAPERS published by: Association of Economists and Managers of the Balkans, Belgrade, Serbia)
• 03 Sep 2020
Mihajlov Carević, Miroslava • Petrović, Milena • Denić, Nebojša
Numerous researches in the previous period have shown the effectiveness of mathematical
learning with the use of information and communication technologies (ICT) and mathematical software packages. Also, through theoretical studies and research results, the quality of mathematics teaching in schools was examined. The results of the research of he authors of this paper showed the lack of a visual-logical approach in solving mathematical problems. Primary and secondary school students are prim ...
(Univerzitetska misao - časopis za nauku, kulturu i umjetnost, Novi Pazar)
• 01 May 2018
Mihajlov Carević, Miroslava • Petrović, Milena • Denić, Nebojša
Savremena nastava matematike na svim nivoima obrazovanja uglavnom se svodi na primenu algebarskih formula i algebarskih postupaka. Vizuelno-logički pristup sagledavanju i rešavanju matematičkih zadataka vrlo malo je prisutan u nastavi matematike. Takvu praksu bi trebalo promeniti jer je vizuelizacija od velike važnosti u procesu učenja i razumevanja matematike.U ovom radu prikazujemo uvođenje figurativnih brojeva u nastavu matematike šestog razreda osnovne škole i njihov doprinos razvoju sposobn ...
UNIVERSITY THOUGHT - Publication in Natural Sciences
(Prirodno-matematički fakultet Univerziteta u Prištini u Kosovskoj Mitrovici, Srbija)
• 01 Apr 2024
Petrović, Milena • Ivanović, Milica • Đorđević, Marijana
We analyze a performance profile of several accelerated and hybrid accelerated methods. All comparative methods
are at least linearly convergent and have satisfied numerical characteristics regarding tested metrics: number of
iterations, CPU time and number of function evaluations. Among the chosen set of methods we numerically show
which one is the most efficient and the most effective. Therewith, we derived a conclusion about what type of method
is more preferable to use considering analyz ...
Numerical algorithms
(Springer)
• 01 Apr 2024
Petrović, Milena • Rakočević, Vladimir • Kontrec, Nataša • Panić, Stefan • Ilić, Dejan
We present a gradient descent algorithm with a line search procedure for solving unconstrained optimization problems which is defined as a result of applying Picard-Mann hybrid iterative process on accelerated gradient descent S M method described in Stanimirović and Miladinović (Numer. Algor. 54, 503–520, 2010). Using merged features of both analyzed models, we show that new accelerated gradient descent model converges linearly and faster then the starting S M method which is confirmed trough d ...
Bulletin of Natural Sciences Research
• 01 Apr 2024
Gulan, Ljiljana • Jakšić, Tatjana • Milenković, Biljana • Stajić, Jelena
This paper deals with investigations of elemental concentrations and soil-to-moss transfer factors of radionuclides in area of municipalities Kosovska Mitrovica and Zubin Potok. Twelve samples of soil and moss Hypnum cupressiforme Hedw. were collected during May 2018. Transfer factors of radionuclides: 226Ra, 232Th, 40Kand 137Cs were calculated with regard to elemental concentrations of radionuclides in soil and moss samples. Analysis was done in order to indicate the different ways of adopting ...
XIII Balkan Conference on Operational Research Proceedings: Belgrade, Serbia
(The Mathematical Institute of the Serbian Academy of Sciences and Arts (SANU))
• 01 Apr 2024
Kontrec, Nataša • Panić, Stefan • Petrović, Milena
This paper presents a novel approach for estimation of repair rate in an observed system comprised of two or more components. The presented approach is based on calculation of probability density function of maximal and minimal system’s repair time by observing the repair rates of its components. Based on the obtained information it can be concluded in which time interval the repair or replacement should be completed in order to achieve the desired level of availability. The model can be further ...
(Elsevier)
• 02 Sep 2018
Valjarević, Aleksandar • Srećković-Batoćanin, Danica • Valjarević, Dragana • Matović, Vesna
There are about 240 geothermal occurrences with 60 commercial spas included in, which are spread throughout the territory of Serbia. The majority of springs and other surface manifestations are located along the south-eastern edge of the country. Three spas Lukovska, Prolom and Kursumlijska are with the highest geothermal potential and balneology utilization. They are situated in the vicinity of Kursumlija, one of the largest municipalities in Serbia, but with poor economic development. Although ...
(Society of Physical Chemists of Serbia)
• 28 Sep 2018
Bondžić, Aleksandra • Vujačić Nikezić, Ana • Kalska, Beata • Klekota, Urszula • Laban, Bojana • Vodnik, Vesna • Vasić, Vesna
The paper presents the results of study of interaction between citrate capped gold nanoparticles (AuNPs) and some antitumor gold complexes with pyridine ligands (AubipyC, AubipyOH and AupyOAc), in order to elucidate the possibility for their tracking in physiological fluids using NPs. The surface plasmon absorption band of AuNPs at 524 nm decreased in the presence of selected complexes, while the new broad band appeared at ~ 640 nm, which showed the increase in intensity with time upon the addit ...
Journal of Lightwave Technology
(IEEE)
• 03 Jul 2019
Savović, Svetislav • Simović, Ana • Drljača, Branko • Djordjevich, Alexandar • Stepniak, Grzegorz • Bunge, Christian Alexander • Bajić, Jovan
A method is proposed for predicting the evolution of the power distribution along graded-index plastic optical fibers. This method is verified against our recently reported measurements. The strong influence of mode coupling on the power distribution is demonstrated on a specific graded-index plastic fiber to illustrate the influence of mode coupling in applications, such as
data transmission, power delivery, and sensing systems.
Optics and Laser Technology
(Elsevier)
• 02 Nov 2018
Simović, Ana • Savović, Svetislav • Drljača, Branko • Djordjevich, Alexandar
We propose a multimode W type (doubly clad) plastic optical fiber which takes the characteristic W-shaped index profile designed from a multimode singly clad step index plastic optical fiber upon modification of the cladding layer of the latter. For different widths of the inner cladding and refractive index of the outer cladding, the bandwidth and steady-state loss are determined for such W type plastic optical fiber. We have shown that bandwidth of W type plastic optical fiber is significantly ...
Optics and Laser Technology
(Elsevier)
• 04 Apr 2018
Savović, Svetislav • Djordjevich, Alexandar • Simović, Ana • Drljača, Branko
We investigate the influence of mode coupling on space division multiplexing capability of three multimode step-index plastic optical fibers with different strengths of mode coupling. Results show that mode
coupling significantly limits the fiber length at which the space division multiplexing can be realized with
a minimal crosstalk between the neighbor optical channels. Three, four and five spatially multiplexed
channels in the investigated multimode step-index plastic optical fibers can be ...
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 ...
Mathematics and computer sciences
(Mathematics and computer sciences)
• 10 Oct 2022
Perić, Zoran • Marković, Aleksandar • Kontrec, Nataša • Nikolić, Jelena • Petković, Marko • Jovanović, Aleksandra
The Gaussian Q-function has considerable applications in numerous areas of science and engineering. However, the fact that a closed-form expression for this function does not exist encourages finding approximations or bounds of the Q-function. In this paper, we determine analytically two novel interval upper bound Q-function approximations and show that they could be used efficiently not only for the symbol error probability (SEP) estimation of transmission over Nakagami-m fading channels, but a ...
Surfaces and Interfaces
• 01 Apr 2024
Stanković, Dalibor • Ognjanović, Miloš • Fabián, Martin • Viktorovich Avdin, Vyacheslav • Manojlović, Dragan • Vranješ Đurić, Sanja • Petković, Branka
The goal of this work was to develop green electrode material that unites all advantages of domestic made, synthesized porous carbon powder and ceria dioxide nanoparticles known due to exceptional catalytic properties. Thermal decomposition of Novolac phenol-formaldehyde resin and cerium sulfate resulting in producing a high-performance CeO2 porous carbon material highly sensitive to dopamine (DA) electrooxidation. Morphological
and structural characteristics of the material were determined by ...
Dalton Trans.
• 01 Apr 2024
Savić, Nada • Petković, Branka • Vojnović, Sandra • Mojicevic, Marija • Wadepohl, Hubert • Olaifa, Kayode • Marsili, Enrico • Nikodinović-Runić, Jasmina • Djuran, Miloš • Glišić, Biljana
New dinuclear silver(I) complexes with N,N’,N’’,N’’’-tetrakis(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane (tpmc), [Ag2(NO3)(tpmc)]NO3·1.7H2O (1), [Ag2(CF3SO3)2(tpmc)] (2), and [Ag2(tpmc)](BF4)2 (3) were synthesized and characterized by NMR (1H and 13C), IR and UV-Vis spectroscopy, cyclic voltammetry and molar conductivity measurements. The molecular structures of the complexes were determined by single-crystal X-ray diffraction analysis. The spectroscopic and crystallographic data showed ...
Microchemical Journal
• 01 Apr 2024
Knežević, Sara • Ognjanović, Miloš • Nedić, Nemanja • Mariano, José • Milanović, Zorana • Petković, Branka • Antić, Bratislav • Vranješ Djurić, Sanja • Stanković, Dalibor
In order to ensure high food quality, one of the prime importance is the detection and quantification of histamine, well known marine food poison. In this work, we constructed novel electrochemical biosensor for the detection of histamine based on gold nanoparticles decorated on manganese dioxide (Au/MnO2) and used for modification of screen-printed carbon electrode (Au/MnO2@SPCE). The constructed sensor was then used for the estimation of histamine content in a single drop. Materials used in th ...
Electrochimica Acta
• 01 Apr 2024
Jevtić, Sonja • Vukojević, Vesna • Đurđić, Slađana • Pergal, Marija • Manojlović, Dragan • Petković, Branka • Stanković, Dalibor
This work present a new approach for the detection of relatively new herbicide pethoxamid (POA), a first electrochemical behavior and determination based on its oxidation on boron-doped diamond electrode in Britton-Robinson buffer solution at pH 4. Square wave voltammetric technique was used for quantification of POA at anodic potential of 1.35 V vs reference Ag/AgCl electrode. The proposed electroanalytical method is operational in the linear working range from 3 to 100 μM of POA with a limit o ...
Environmental Science and Pollution Research
• 01 Apr 2024
Pergal, Marija • Kodranov, Igor • Dojčinović, Biljana • Avdin, Viacheslav • Stanković, Dalibor • Petković, Branka • Manojlović, Dragan
Chlorine dioxide (ClO2) degradation of the organophosphorus pesticides azamethiphos (AZA) and dimethoate (DM) (10 mg/L) in deionized water and in Sava River water was investigated for the first time. Pesticide degradation was studied in terms of ClO2 level (5 and 10 mg/L), degradation duration (0.5, 1, 2, 3, 6, and 24 h), pH (3.00, 7.00, and 9.00), and
under light/dark conditions in deionized water. Degradation was monitored using high-performance liquid chromatography. Gas chromatography coupl ...
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 ...
Optica Applicata
(Oficyna Wydawnicza Politechniki Wroclawskiej)
• 22 Mar 2018
Smilić, Marko • Perić, Zoran • Milić, Dejan • Marković, Aleksandar • Savić, Milan
In this paper, the influence of a zero and a non-zero boresight pointing errors on the performances of free-space optic transmission over the Málaga atmospheric turbulence channel is considered. Closed form expressions for a zero boresight channel model probability density function, non-zero boresight channel model probability density function, as well as a bit-error rate over a binary phase shift keying modulation transmission are provided. Numerical results for zero and non-zero boresight poin ...
Electronics and Electrical Engineering
(Kaunas University of Technology)
• 22 Jun 2018
Stevanović, Aco • Panić, Stefan • Spalević, Petar • Prlinčević, Bojan • Savić, Milan
Modelling of complex wireless transmission scenario over fading channels in the presence of multiple co- channel (CCI) interferers will be presented in this paper. Propagation environment will be modelled with general kappa- mu shadowed model, which can be reduced to other well- known model as its singularities. Probability density function (PDF) and cumulative distribution function (CDF) of resulting signal-to-interference (SIR) ratio statistics at the reception will be derived in the rapidly c ...
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 ...
Macedonian Journal of Chemistry and Chemical Engineering
• 01 Apr 2024
Krstić, Milena • Petković, Branka • Milčić, Miloš • Mišić, Dušan • Santibanez, Juan Francisco
Two new nitrato complexes of zinc and nickel with 1,4,8,11-tetrakis(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane (tpmc), have been synthesized and characterized. The IR spectral peaks showed that the coordinated and ionic nitrate ions are in agreement with the formula proposed by elemental anal-ysis. Conductometric titrations predicted methanol to be a convenient solvent for synthesis and revealed the stoichiometry of the complexes, while molar electrical conductivities indicated a 1 : 3 c ...
Elektronika ir Elektrotechnika
(Kaunas University of Technology)
• 23 Aug 2021
Perić, Zoran • Denić, Bojan • Savić, Milan • Vučić, Nikola • Simić, Nikola
This paper considers the design of a binary scalar quantizer of Laplacian source and its application in compressed neural networks. The quantizer performance is investigated in a wide dynamic range of data variances, and for that purpose, we derive novel closed-form expressions. Moreover, we propose two selection criteria for the variance range of interest. Binary quantizers are further implemented for compressing neural network weights and its performance is analysed for a simple classification ...
Int. J. Electrochem. Sci.
• 01 Apr 2024
Đurđić, Slađana • Vukojević, Vesna • Jevtić, Sonja • Pergal, Marija • Petković, Branka • Stanković, Dalibor
In this work, for the first time we proposed electrochemical behavior and development of an analytical procedure for quantification of pesticide clomazone. Electrochemical behavior of clomazone’s at boron-doped diamond electrode is characterized with irreversible oxidation at potential of around 1.6 V, in Britton-Robinson buffer solution at pH 2. It was found that potential of this oxidation was not pH dependent excluding presence of proton in the electrochemical reaction. Square wave voltammetr ...
Information Technology and Control
(Kaunas University of Technology)
• 24 Sep 2021
Perić, Zoran • Denić, Bojan • Savić, Milan • Dinčić, Milan • Mihajlov, Darko
Quantization and compression of neural network parameters using the uniform scalar quantization is carried out in this paper. The attractiveness of the uniform scalar quantizer is reflected in a low complexity and relatively good performance, making it the most popular quantization model. We present a design approach for the memoryless Laplacian source with zero-mean and unit variance, which is based on iterative rule and uses the minimal mean-squared error distortion as a performance criterion. ...
Chemistry & Biodiversity
(Wiley-VHCA AG, Zurich, Switzerland)
• 15 Jun 2020
Randjelović, Pavle • Radulović, Niko • Stojanović, Nikola • Dekić, Vidoslav • Dekić, Biljana • Stojiljković, Nenad • Ilić, Sonja
In this work we explored the possible polypharmacological potential of the already established antimicrobials against gastrointestinal pathogens, 4-(alkylamino)-3-nitrocoumarins, as antianxiety agents, using a battery of in vivo experiments. Three chosen coumarin derivatives, differing in the substituent (sec-butylamino, hexadecylamino, or benzylamino) at position 4, at the doses of 25, 50 and 100 mg kg-1, were evaluated in light/dark, open-field, horizontal wire and diazepam-induced sleep model ...
Information
(MDPI)
• 27 Oct 2020
Perić, Zoran • Denić, Bojan • Savić, Milan • Despotović, Vladimir
A compression method based on non-uniform binary scalar quantization, designed for
the memoryless Laplacian source with zero-mean and unit variance, is analyzed in this paper. Two quantizer design approaches are presented that investigate the effect of clipping with the aim of reducing the quantization noise, where the minimal mean-squared error distortion is used to determine the optimal clipping factor. A detailed comparison of both models is provided, and the performance evaluation in a wide ...
International Journal of Environmental Analytical Chemistry
• 01 Apr 2024
Vukojević, Vesna • Đurđić, Slađana • Jevtić, Sonja • Pergal, Marija • Marković, Aleksandar • Mutić, Jelena • Petković, Branka • Stanković, Dalibor
In this work, the electrochemical behaviour and the subsequent development of an analytical procedure for quantification of pesticide azamethiphos, using boron-doped diamond (BDD) electrode are reported for the first time. It was found that azamethiphos
electrochemical behaviour is irreversible oxidation at the potential of around 1.70 V, in 1 M nitric acid (pH 0). Also, it was found that potential of this oxidation was not pH dependent which can be attributed to the no proton involvement in el ...
University thought
• 01 Apr 2024
Jevtić, Sonja • Stanković, Dalibor • Jokić, Anja • Petković, Branka
This review paper shows the progress made in the last five years in electrochemical methods applied for the purpose of detection and quantification of pesticides - nowadays the most serious pollutants of the environment. Most pesticides can be successfully analyzed by chromatographic techniques, but because of high prices and immobility of the apparatus, the complexity of the method and the necessary special preparation of the samples, electrochemical methods have been recognized as an excellent ...
Polish Journal of Environmental Studies
(HARD Publishing Company s.c.)
• 08 Sep 2020
Pecev-Marinković, Emilija • Miletić, Ana • Pavlović, Aleksandra • Tošić, Snežana • Mitić, Milan • Rančić, Sofija • Dekić, Biljana
The objective of this paper was to develop and apply the kinetic-spectrophotometric method for the determination of the pesticide dicamba in infant baby foods available in Serbia. The method is based on the inhibition effect of dicamba on the oxidation of sulfanilic acid (SA) by hydrogen peroxide in universal buffer (pH = 9.66) in the presence of Co2+ ion. The reaction was monitored spectrophotometrically at 368 nm. The HPLC method was used as a comparative method to verify the results of the ki ...
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 ...
University thought
• 01 Apr 2024
Jokić, Anja • Petković, Branka • Jevtić, Sonja • Vasić, Vesna • Laban, Bojana
The iron oxide nanoparticles (Fe2O3 NPs) were synthesized from two different iron salts by solid-state synthesis method. The synthesized powder of Fe2O3 NPs is soluble in water, and the colloidal dispersion was characterized by TEM, FTIR, UV-Vis spectroscopy and zeta potential measurements. Obtained NPs are spherical in shape with narrow particle size distribution and an average diameter of 3 nm. Further, the possible application of Fe2O3 NPs was proposed, due to significant electroanalytical si ...
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
(Wiley-VHCA AG, Zurich, Switzerland)
• 07 May 2019
Dekić, Biljana • Ristić, Milenko • Ristić, Novica • Mladenović, Marko • Dekić, Vidoslav • Ranđelović, Vladimir • Radulović, Niko
Some carnation species (Dianthus spp., Caryophyllaceae) exhibit a strong resistance to drought stress that is connected with the increased surface wax formation. Wax composition is unknown for the majority of Dianthus spp. Herein, mass spectral and gas chromatographic data, in combination with synthesis and chemical transformations (transesterification and synthesis of dimethyl disulfide adducts), enabled the identification of 151 constituents of diethyl-ether washings of fresh flowers of Dianth ...
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 ...
Zeitschrift für Kristallographie - New Crystal Structures
• 14 Oct 2019
Dekić, Vidoslav • Rodić, Marko • Radulović, Niko • Ristić, Milenko • Dekić, Biljana • Gurešić, Dejan • Ristić, Novica
C16H12N2O4, triclinic, P1 (no. 2), a = 10.7105(5) Å, b = 11.2685(5) Å, c = 13.0145(6) Å, α = 99.292(4)°, β = 109.607(4)°, γ = 96.771(4)°, V = 1435.01(12) Å3, Z = 4, Rgt(F) = 0.0427, wRref(F2) = 0.1124, T = 295(2) K.
CCDC no.: 1957160
Czech Journal of Food Sciences
• 25 Oct 2019
Živić, Nebojša • Milošević, Slaviša • Dekić, Vidoslav • Dekić, Biljana • Ristić, Novica • Ristić, Milenko • Sretić, Ljiljana
The content of phytochemicals, total phenolics, total flavonoids and antioxidant potential of extracts of Juniperus communis L. and Juniperus oxycedrus L. berries were determined. Ethanol, ethyl acetate and chloroform were used for the process of extraction. Phytochemical monitoring was based on already known methods, while in vitro antioxidant activities were done by DPPH assay. Phytochemical screening showed a wide spectrum of phytochemicals. Ethanolic extract of Juniperus communis L. possesse ...
Zeitschrift für Kristallographie - New Crystal Structures
• 08 May 2019
Ristić, Milenko • Rodić, Marko • Radulović, Niko • Dekić, Biljana • Dekić, Vidoslav • Ristić, Novica • Gurešić, Dejan
C22H18O10Zn, triclinic, P1̄ (no. 2), a = 7.9616(3) Å, b = 9.5386(3) Å, c = 14.2569(4) Å, α = 81.713(3)°, β = 82.724(3)°, γ = 73.103(3)°, V = 1021.03(6) Å3, Z = 2, Rgt(F) = 0.0223, wRref(F2) = 0.0603, T = 295(2) K.
CCDC no.: 1905428
Applicable Analysis and Discrete Mathematics
(University of Belgrade - School of Electrical Engineering)
• 26 Oct 2021
Najdanović, Marija • Velimirović, Ljubica • Rančić, Svetozar
In this paper we consider infinitesimal bending of the second order of curves
and knots. The total torsion of the knot during the second order infinitesimal
bending is discussed and expressions for the first and the second variation of
the total torsion are given. Some examples aimed to illustrate infinitesimal
bending of knots are shown using figures. Colors are used to illustrate torsion
values at different points of bent knots and the total torsion is numerically
calculated.
Mediterranean Journal of Mathematics
(Birkhaeuser Verlag AG)
• 11 May 2022
Najdanović, Marija • Velimirović, Ljubica • Vesić, Nenad
Infinitesimal deformations of subspaces of a generalized Riemannian
space are studied in this paper. Variations of some geometric
objects are found. Necessary and sufficient conditions which provide the
existence of a geodesic infinitesimal deformation of a generalized Riemannian
space are obtained. Basic equations of a geodesic infinitesimal
deformation such as a system of differential equations which determined
an infinitesimal deformation field are given.
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.
Journal of Knot Theory and Its Ramifications
(World Scientific Publishing Co. Pte. Ltd.)
• 12 Sep 2019
Kauffman, Louis • Velimirović, Ljubica • Najdanović, Marija • Rančić, Svetozar
We discuss the infinitesimal bending of curves and knots in R3. A brief overview of the results on the infinitesimal bending of curves is outlined. Change of the Willmore energy, as well as of the Möbius energy under infinitesimal bending of knots is considered. Our visualization tool devoted to visual representation of infinitesimal bending of knots is presented.
Journal of Knot Theory and Its Ramifications
(World Scientific Publishing Co. Pte. Ltd.)
• 03 Jan 2019
Najdanović, Marija • Rančić, Svetozar • Kauffman, Louis • Velimirović, Ljubica
In this paper, we consider infinitesimal bending of the second-order of curves and
knots. The total curvature of the knot during the second-order infinitesimal bending is
discussed and expressions for the first and the second variation of the total curvature
are given. Some examples aimed to illustrate infinitesimal bending of knots are shown
using figures. Colors are used to illustrate curvature values at different points of bent
knots and the total curvature is numerically calculated.
UNIVERSITY POLITEHNICA OF BUCHAREST SCIENTIFIC BULLETIN-SERIES A-APPLIED MATHEMATICS AND PHYSICS
(UNIVERSITY POLITEHNICA OF BUCHAREST)
• 01 Apr 2024
Stojanović, Vladica • Kevkić, Tijana • Vujaković, Jelena • Jelić, Gordana • Pažun, Brankica
In this paper, an application of the Stochastic Mellin Transforms (SMTs) in determination of the probability distribution functions (PDFs) of the Stochastic Volatility (SV) models is proposed. In that aim, three basic SV time series with Gaussian innovations have been considered, and their PDFs were obtained by using the inverse SMT formula.
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 ...
Mathematics
(MDPI (Basel, Switzerland))
• 28 Mar 2019
Vujaković, Jelena • Kishore, Gajula Naveen Venkata • Panda Ranga Rao, Konduru • Radenović, Stojan • Sadik, Shaik
In this paper, we prove a unique common coupled fixed point theorem for two pairs of w-compatible mappings in Sb -metric spaces. We also furnish an example to support our main result.
Mathematics
(MDPI (Basel, Switzerland))
• 06 Apr 2019
Vujaković, Jelena • Aydi, Hassen • Radenović, Stojan • Mukheimer, Aiman
We improve and generalize some new results in fixed point theory in the context of partial b-metric spaces
Mathematics
(MDPI (Basel, Switzerland))
• 27 May 2019
George, Reny • Tamrakar, Ekta • Vujaković, Jelena • Pathak, Hemant Kumar • Velusamy, Selvavinayagam
In this paper, we introduce the (C,Ψ∗,G) class of contraction mappings using C-class functions and some improved control functions for a pair of set valued mappings as well as a pair of single-valued mappings, and prove common fixed point theorems for such mappings in a metric space endowed with a graph. Our results unify and generalize many important fixed point results existing in literature. As an application of our main result, we have derived fixed point theorems for a pair of α -admissible ...
Mathematics
(MDPI (Basel, Switzerland))
• 25 Oct 2019
Saleem, Naeem • Vujaković, Jelena • Baloch, Wali Ullah • Radenović, Stojan
In this paper, we introduce the concept of coincidence best proximity point for multivalued Suzuki-type α -admissible mapping using θ -contraction in b-metric space. Some examples are presented here to understand the use of the main results and to support the results proved herein. The obtained results extend and generalize various existing results in literature
Journal of Inequalities and Applications
(Springer Nature SharedIt)
• 09 Nov 2019
Mukheimer, Aiman • Vujaković, Jelena • Hussain, Azhar • Aydi, Hassen • Radenović, Stojan • Yaqoob, Saman
The notion of nonlinear (Fs,L)-contractive multivalued operators is initiated and some related fixed point results are considered. We also give an example to show the validity of obtained theoretical results. Our results generalize many existing ones in the literature.
Mathematics
(MDPI (Basel, Switzerland))
• 01 Apr 2020
Baradol, Pravin • Vujaković, Jelena • Gopal, Dhananjay • Radenović, Stojan
In this paper, we provide an approach to establish the Banach contraction principle (for the case λ∈[0,1)) , Edelstein, Reich, and Meir–Keeler type contractions in the context of graphical rectangular b-metric space. The obtained results not only enrich and improve recent fixed point theorems of this new metric spaces but also provide positive answers to the questions raised by Mudasir Younis et al. (J. Fixed Point Theory Appl., doi:10.1007/s11784-019-0673-3, 2019).
Mathematics
(MDPI (Basel, Switzerland))
• 11 May 2020
Vujaković, Jelena • Mitrović, Slobodanka • Pavlović, Mirjana • Radenović, Stojan
In this manuscript we discuss, consider, generalize, improve and unify several recent results for so-called F-contraction-type mappings in the framework of complete metric spaces. We also introduce (φ,F) -weak contraction and establish the corresponding fixed point result. Using our new approach for the proof that a Picard sequence is a Cauchy in metric space, our obtained results complement and enrich several methods in the existing literature. At the end we give one open question for F-contrac ...
Mathematics
(MDPI (Basel, Switzerland))
• 21 Sep 2020
Vujaković, Jelena • Mitrović, Slobodanka • Mitrović, Zoran • Radenović, Stojan
In the paper, we consider some fixed point results of F-contractions for triangular α-admissible and triangular weak α-admissible mappings in metric-like spaces. The results on F-contraction type mappings in the context of metric-like spaces are generalized, improved, unified, and enriched. We prove the main result but using only the property (F1) of the strictly increasing mapping F:(0,,,+,∞)→(−,∞,,,+,∞). Our approach gives a proper generalization of several results given in current literature.
Mathematics
(MDPI (Basel, Switzerland))
• 07 Jan 2021
Vujaković, Jelena • Ljajko, Eugen • Pavlović, Mirjana • Radenović, Stojan
One of the main goals of this paper is to obtain new contractive conditions using the method of a strictly increasing mapping F:(0,+∞)→(−∞,+∞). According to the recently obtained results, this was possible (Wardowski’s method) only if two more properties (F2) and (F3) were used instead of the aforementioned strictly increasing (F1). Using only the fact that the function F is strictly increasing, we came to new families of contractive conditions that have not been found in the existing literature ...
Mathematics
(MDPI (Basel, Switzerland))
• 12 Aug 2021
Mitrović, Slobodanka • Parvaneh, Vahid • De la Sen, Manuel • Vujaković, Jelena • Radenović, Stojan
In this article, we generalize, improve, unify and enrich some results for Jaggi-W-contraction-type mappings in the framework of b-metric-like spaces. Our results supplement numerous methods in the existing literature, and we created new approach to prove that a Picard sequence is Cauchy in a b-metric-like space. Among other things, we prove Wardowski’s theorem, but now by using only the property (W1). Our proofs in this article are much shorter than ones in recently published papers.
Mathematics
(MDPI (Basel, Switzerland))
• 21 Dec 2021
Vujaković, Jelena • Kontrec, Nataša • Tošić, Marina • Fabiano, Nicola • Radenović, Stojan
The main purpose of this paper is to improve, generalize, unify, extend and enrich the recent results established by Dung and Hang (2015), Piri and Kumam (2014, 2016), and Singh et al. (2018). In our proofs, we only use the property (F1) of Wardowski’s F-contraction, while the many authors in their papers still use all tree properties of F-contraction as well as two new properties introduced by Piri and Kumam. Our approach in this paper indicates that for most results with F-contraction, propert ...
Vojnotehnički glasnik/Military Technical Courier
• 15 Jul 2020
Vujaković, Jelena • Radenović, Stojan
This paper establishes some new results of Piri–Kumam–Dung-type mappings in a complete metric space.Тhe goal was to improve the already published results.
Methods: Using the property of a strictly increasing function as well as the
known Lemma formulated in (Radenović et al, 2017), the authors have
proved that a Picard sequence is a Cauchy sequence
Novi Sad Journal of Mathematics (NSJOM)
(University of Novi Sad, Faculty of Sciences, Department for Mathematics and Informatics)
• 12 Jan 2019
Dedović, Nebojša • Kishore, Gajula Naveen Venkata • Ram Prasad, Daripally • Vujaković, Jelena
In this paper we give some applications to integral equations as well as homotopy theory via Suzuki type fixed point theorems in partially ordered complete Sb - metric space by using generalized contractive conditions. We also furnish an example which supports our main result.
Novi Sad Journal of Mathematics (NSJOM)
(Department of Mathematics and Informatics, Faculty of Sciences, Novi Sad)
• 05 Jun 2018
Ansari, Arslan Hojat • Došenović, Tatjana • Radenović, Stojan • Saleem, Naeem • Šešum-Čavić, Vesna • Vujaković, Jelena
In this paper, we generalized the results presented in the paper W. Long, S. Khaleghizadeh, P. Salimi, S. Radenović and S. Shukla, Some new fixed point results in partially ordered metric spaces via admissible mappings, Fixed Point Theory Appl. (2014), 2014:117, in the framework of partial metric spaces by using C−class function in ordered structure. Also, we provide an example to support our theoretical results and shows that obtained results are potential generalization of the already existing ...
Matematički vesnik
(Društvo matematičara Srbije)
• 03 Sep 2018
Mitrović D., Zoran • Radenović, Stojan • Vetro, Francesca • Vujaković, Jelena
In this paper we complement and improve fixed point results established on
TAC-contractive mappings in the framework of b-metric spaces. Our analysis starts by a
recent paper of Babu and Dula [G. V. R. Babu and T. M. Dula, Fixed points of generalized
TAC-contractive mappings in b-metric spaces, Matematiˇcki Vesnik 69 (2017), no. 2, 75–88].
Air Quality, Atmosphere & Health
(Springer)
• 01 Apr 2024
Gulan, Ljiljana • Stajic, Jelena M. • Spasić, Dušica • Forkapić, Sofija
This study was conducted toevaluate the influence of thermal retrofit on radon levels in workrooms,and to determine whetherthe radon concentrationin the building changes after the application of retrofit measures.In thefirst survey, digital radon detector Airthings Corentium Homewas usedfor one month radon measurementsduring heating season 2018/19.The dailyaveraged radon concentrationsvaried from 37-573 Bq/m3for ten selectedworkrooms, while hourly averaged radon measurements showed extreme varia ...
Indoor Air
(Wiley)
• 01 Apr 2024
Ljiljana, Gulan • Forkapić, Sofija • Spasić, Dušica • Radovanović Živković, Jelena • Hasman, Jan • Lakatoš, Robert • Samardžić, Selena
This study was performed to investigate radon levels in dwellings in the mining area
near the town of Kosovska Mitrovica. The Passive radon technique based on the charcoal
canister test kit conducted in summer and autumn 2019 showed unexpected results.
The reference level of 300 Bq/m3 for indoor radon concentration was exceeded in 15 of 26 dwellings. Preliminary measurements of gamma dose rate in some dwellings built from local stone showed values from 0.30 to 0.45 μSv/h, while 75% of measure ...
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 ...
Chemosphere
(Elsevier)
• 01 Apr 2024
Gulan, Ljiljana • Penjišević, Ivana • Stajic, Jelena M. • Milenković, Biljana • Zeremski, Tijana • Stevanović, Vladica • Valjarević, Aleksandar
This study aims to estimate geothermal potential, radioactivity levels, and environmental pollution of sixmost popular spas in Central Serbia (Ovcar, Gornja Trepca, Vrnjacka, Mataruska, Bogutovacka and Sokobanja), as well as to evaluate potential exposure and health risks for living and visiting population. Thermal possibilities of the studied spas showed medium and low geothermal potential with totalthermal power of 0.025MW. Gamma dose rates in air varied from 63 to 178 nSv h-1. Specific activi ...
Radiation Protection Dosimetry
• 01 Apr 2024
Yarmoshenko • Žunić, Zora S. • Mishra, Rosaline • Čeliković, Igor • Stojanovska, Zdenka • Yarmoshenko, Ilia V. • Malinovsky, Georgy • Veselinović, Nenad • Gulan, Ljiljana • Ćurguz, Zoran • Vaupotič, Janja • Ujic, Predrag • Kolarž, Predrag • Milić, Gordana • Kovacs, Tibor • Sapra, Balvindar K. • Kavasi, Norbert • Sahoo, Sarata K.
The main contribution to population exposure is due to radon and thoron progenies and not radon itself. The aim of this study was therefore to estimate annual effective dose using the results of Direct Radon and Thoron Progeny Sensors were exposed in 69 selected schools and 319 dwellings in several regions of Balkans: in Serbia: regions of Sokobanja and Kosovo and Metohija, Republic of Macedonia, Republic of Srpska and Slovenia. Obtained average total effective doses are in the range from 0.22 m ...
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 ...
Environmental Geochemistry and Health
(Springer)
• 13 Mar 2018
Stevanović, Vladica • Gulan, Ljiljana • Milenković, Biljana • Valjarević, Aleksandar • Zeremski, Tijana • Penjišević, Ivana
Activity levels of natural and artificial radionuclides and content of ten heavy metals (As, Cd,
Co, Cr, Cu, Mn, Ni, Pb, Zn and Hg) were investigated in 41 soil samples collected from Toplica region located in the south part of Serbia. Radioactivity was determined by gamma spectrometry using HPGe detector. The obtained mean activity concentrations ± standard deviations of radionuclides 226Ra, 232Th, 40K and 137Cs were 29.9 ± 9.4, 36.6 ± 11.5, 492 ± 181 and 13.4 ± 18.7 Bq kg-1, respectively. Acc ...
FACTA UNIVERSITATIS Series: Physics, Chemistry and Technology
(Faculty of Sciences and Mathematics, University of Niš)
• 01 Apr 2024
Radulović, Niko • Ristić, Milenko • Ristić, Novica • Dekić, Vidoslav • Dekić, Biljana • Mladenović, Marko
The genus Dianthus L. (Caryophyllaceae) comprises over 300 species of herbaceous plants that are spread over a vast area, especially in the Mediterranean region. Species of this genus, represented with 38 taxa in the Serbian flora, have attracted attention due to the very beautiful flower color combinations ranging from white to deep purple [1]. This characteristic pigmentation, among several other morphological traits, distinguishes Dianthus from other genera within the family Caryophyllaceae, ...
Bulletin of Natural Sciences Research
(Faculty of Sciences and Mathematics, University of Priština in Kosovska Mitrovica)
• 01 Apr 2024
Ristić, Milenko • Dekić, Biljana • Radulović, Niko • Aksić, Marija
In this research, the synthesis of a new azine derivative with coumarin moiety was performed in three reaction steps, starting from 4-hydroxycoumarin. The first step in synthesis was the acetylation of 4-hydroxycoumarin to yield 3-acetyl-4-hydroxycoumarin and then the obtained 3-acetyl-4-hydroxycoumarin was reacted with hydrazine hydrate and give a corresponding hydrazone. Condensation of the hydrazone with 4-ethoxy-3-methoxybenzaldehyde afforded the target compound 1-[1-(4-hydroxy-2-oxo-2H-chro ...
UNIVERSITY THOUGHT Publication in Natural Sciences
(Faculty of Sciences and Mathematics, University of Priština in Kosovska Mitrovica)
• 01 Apr 2024
Dekić, Vidoslav • Radulović, Niko • Ristić, Milenko • Dekić, Biljana • Ristić, Novica
This research involves the reaction of 4-chloro-3-nitrocoumarin and (4-methoxyphenyl)methanamine, whereby a novel coumarin derivative 4-[(4-methoxybenzyl) amino]-3-nitro-2H-chromen-2-one was obtained in good yield. The reaction was carried out in ethyl acetate, in the presence of triethylamine. Also, a detailed spectral analysis of a new coumarin derivative is presented. Resonance assignment was achieved using one- (1H NMR and 13C NMR) and two-dimensional NMR techniques (1H-1H-COSY, NOESY, HSQC, ...
UNIVERSITY THOUGHT Publication in Natural Sciences
(Faculty of Sciences and Mathematics, University of Priština in Kosovska Mitrovica)
• 01 Apr 2024
Dekić, Vidoslav • Ristić, Novica • Dekić, Biljana • Ristić, Milenko
Considering the facts that phenolic compounds have many pharmacological effects, as well that antioxidant effect of phenolic compounds has been proven in various experimental systems, aim of this research was to determine the content of total phenols and flavonoids and evaluation of antioxidant activity in ethanol, ethyl acetate and chloroform extracts of fruits and leaves of the plant species Crataegus monogya Jacq., which is known as common hawthorn. The content of total phenolic compounds was ...
UNIVERSITY THOUGHT Publication in Natural Sciences
(Faculty of Sciences and Mathematics, University of Priština in Kosovska Mitrovica)
• 01 Apr 2024
Ristić, Novica • Radulović, Niko • Dekić, Biljana • Ristić, Milenko • Dekić, Vidoslav
Synthesis, spectral characterization, and evaluation of in vitro antioxidant activity of a new coumarin derivative, 4- ((1,3,4-thiadiazol-2-yl)amino)-3-nitro-2H-chromene-2-one, are described. The synthesis of the new product was performed in three reaction steps, with a good overall yield (78%). The structure was corroborated by detailed spectral analysis, including the 1D and 2D NMR experiments (1H- and 13C NMR; 1H-1H COSY, NOESY, HSQC, and HMBC). The in vitro antioxidant activity was evaluated ...
Journal of Modern Optics
(Taylor & Francis)
• 28 Aug 2019
Savović, Svetislav • Djordjevich, Alexandar • Simović, Ana • Drljača, Branko
By solving the power flow equation, we investigate the influence of mode coupling on space division
multiplexing capability of three multimode step-index silica optical fibres with a different strengths
of mode coupling. Results show that mode coupling significantly limits the length of these fibres
at which the space division multiplexing can be realized with a minimal crosstalk between the
neighbour optical channels. This is most pronounced in silica optical fibres with the strongest mode ...
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)
• 11 May 2020
Savović, Svetislav • Djordjevich, Alexandar • Simović, Ana • Drljača, Branko
We propose an angular division multiplexing in new designed multicore plastic optical fiber
with seven cores arranged in a hexagonal array. The influence of mode coupling on two-channel
angular division multiplexing capability in each of seven cores is investigated by solving the
power flow equation. Our numerical results show that mode coupling significantly limits the
fiber length at which the angular division multiplexing can be realized in each of seven cores
with a minimal crosstalk be ...
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 ...
Open Physics
(De Gruyter)
• 26 Jan 2022
Kevkić, Tijana S. • Nikolić, Vojkan R. • Stojanović, Vladica S. • Milosavljević, Dragana D. • Jovanović, Slavica J.
Modeling of the electrostatic potential for fully depleted (FD) silicon-on-insulator (SOI) metal-oxide-semiconductor field effect transistor (MOSFET) is presented in this article. The modeling is based on the analytical solution of two-dimensional Poisson’s equation obtained by using the homotopy perturbation method (HPM). The HPM with suitable boundary conditions results in the so-called HPM solution in general and closed-form, independent of the surface potential. The HPM solution has been app ...
Open Physics
(De Gruyter)
• 10 May 2022
Milosavljević, Dragana D. • Kevkić, Tijana S. • Jovanović, Slavica J.
Photovoltaic (PV) systems are an excellent solution to meet energy demand and protect the global environment in many cases. With the increasing utilization of the PV system worldwide, there is an increasing need for simulation tools to predict the PV system’s performance and profitability. This research includes testing and comparison of PV tools: photovoltaic geographical information system (PVGIS), PVWatts, SolarGIS, RETScreen, BlueSol, PVsyst, HelioScope, PV*SOL, Solarius PV, Solar Pro, PV F- ...
Advanced technologies
(Univerzitet u Nišu - Tehnološki fakultet, Leskovac)
• 10 Jul 2021
Kostić, Marija • Cakić, Suzana • Ristić, Ivan • Marinović-Cincović, Milena • Nikolić, Ljubiša • Samaržija-Jovanović, Suzana
Biodegradable polyurethanes can be the basis for drug delivery systems that
are sensitive to external changes. pH-sensitive polyurethanes (PUs) have been
used successfully as intravaginal rings and specific drug delivery systems for
the colon. In this study, a series of pH-sensitive polyurethane hydrogels with a
change of the polyol component (poly(ethylene glycol) 400/poly(propylene glycol)
2000/poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene
glycol) 1100), sacchari ...
Chemical Industry and Chemical Engineering Quarterly
(Association of Chemical Engeneers of Serbia)
• 24 Jan 2019
Jovanović, Slaviša • Jovanović, Vojislav • Marković, Gordana • Samaržija-Jovanović, Suzana • Milićević, Zoran • Marinović-Cincović, Milena • Budinski-Simendić, Jaroslava
The elastomeric materials based on NR/BR/SBR ternary rubber blend were investigated. The polyisoprene (NR), butadiene (BR) and styrene butadiene (SBR) rubbers were used as network precursors and carbon black (CB) as an active filler (60 phr) for elastomeric materials preparation. For sample preparation, the mass ratio of NR to BR was constant, 1:1, but the SBR content was varied from 0 to 80 phr. The morphological, mechanical and thermal properties of prepared elastomeric materials were determin ...
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 ...
Journal of Thermal Analysis and Calorimetry
(Springer)
• 09 Jul 2022
Samaržija-Jovanović, Suzana • Jovanović, Vojislav • Jovanović, Tijana • Petković, Branka • Marković, Gordana • Porobić, Slavica • Marinović-Cincović, Milena
This work investigated the thermal characteristics of irradiated composite materials formulated on the urea–formaldehyde resin (UF) and differently activated montmorillonite (K10). UF resin with molar ratio F:U = 0.8 was synthesized in situ with differently activated K10. K10 was activated by heating at 400 °C, with sulfuric acid (H2SO4) without and with magnetic stirring. The samples are marked with TK10, AK10, ASK10, UF/TK10, UF/AK10, and UF/ASK10, respectively. The samples were identified b ...
Journal of Thermal Analysis and Calorimetry
(Springer)
• 11 Feb 2022
Samaržija-Jovanović, Suzana • Jovanović, Vojislav • Jovanović, Tijana • Petković, Branka • Marković, Gordana • Porobić, Slavica • Marinović-Cincović, Milena
In this study, the thermal and hydrolytic properties of composite systems based on the urea–formaldehyde resin (UF) and eco-friendly montmorillonite (K10) as formaldehyde (FA) scavenger were examined. UF resin with molar ratio FA:U = 0.8 was synthesized in situ with inactivated, and activated K10. K10 was activated by sulfuric acid (H2SO4) with and without magnetic stirring. The samples are marked with K10(H2SO4),K10(H2SO4)ST, UF/K10(H2SO4), and UF/K10(H2SO4)ST, respectively. X-ray diffraction a ...
Composites: Part B: Engeneering
(Elsevier)
• 15 Jun 2019
Samaržija-Jovanović, Suzana • Jovanović, Vojislav • Petković, Branka • Jovanović, Slaviša • Marković, Gordana • Porobić, Slavica • Marinović-Cincović, Milena
The thermal stability of organic-inorganic nano-composites prepared by a two-stage polymerization of urea-formaldehyde resin (UF) with furfuryl alcohol (FA) and TiO2 before and after irradiation has been researched. The two resins of urea-formaldehyde–TiO2 composites, named: UF/TiO2 and UF/TiO2/FA, were synthesized. The thermal stability of obtained materials was studied by non-isothermal thermo-gravimetric analysis (TG), differential thermal gravimetry (DTG) and differential thermal analysis (D ...
Forests
(MDPI)
• 01 Apr 2024
Gulan, Ljiljana • Stajic, Jelena M. • Zeremski, Tijana • Durlević, Uroš • Valjarević, Aleksandar
In urban areas, forest patches and parks are usually the places where people spend most of their time outdoors. Due to the poor environmental protection policy and insufficient investment in industry and energy, Serbia is often ranked among the countries with the highest environmental pollution in Europe. In recent years, ecological protests have been organized all over the country with the aim of raising ecological awareness and resolving environmental issues. The topic has become particularly ...
Mathmatics
(MDPI)
• 13 Jan 2022
Petrović, Milena J. • Valjarević, Dragana • Ilić, Dejan • Valjarević, Aleksandar • Mladenović, Julija
We propose an improved variant of the accelerated gradient optimization models for solving unconstrained minimization problems. Merging the positive features of either double direction, as well as double step size accelerated gradient models, we define an iterative method of a simpler form which is generally more effective. Performed convergence analysis shows that the defined iterative method is at least linearly convergent for uniformly convex and strictly convex functions. Numerical test resu ...
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 ...
European Journal of Geography
(European Association of Geographers (EUROGEO))
• 10 Sep 2019
Pecelj, Milica • Vagić, Nemanja • Ristić, Dušan • Šušnjar, Sanda • Bogdanović, Uroš
The role of applied geography has been increasing in interdisciplinary research due to the advantage of knowing spatial processes and relations. This role has reflected in the geo-ecological evaluations of a particular geographical area used for different social purposes. This paper represents the GIS analysis of the natural environment of a part of the Drina River flow in wider terms so to apply in recreational tourism. The quantitative V-Wert diversification method has used for the study with ...
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 ...
ELEKTRONIKA IR ELEKTROTECHNIKA
(Kaunas University of Technology)
• 27 Oct 2020
Perić, Zoran • Marković, Aleksandar • Kontrec, Nataša • Panić, Stefan • Spalević, Petar
This paper, by using Borjesson’s and Benitez’s approximation of Q-function, presents a novel and improved composite approximation of Q-function with wide applicability. The presented approach is very general and can be implemented on any observed interval. Based on the proposed approximation of Q-function, the average bit error rate is assessed by observing the transfer over Nakagami-m fading channel. The simplicity of the proposed approximation form in conjunction with yet another feature - utm ...
University Thought - Publication in Natural Science
• 23 Jun 2019
Djosić, Danijel • Stefanović, Caslav • Milić, Dejan • Stefanović, Mihajlo
The paper takes into consideration dual-branch selection combining (SC) diversity reception technique in the presence of dissimilar fading at their branches. We efficiently obtained first and second order closed form statistics at the output of the considered model such as probability density function (PDF), cumulative distribution function (CDF) and average level crossing rate (aLCR). Moreover, obtained results are numerically presented for various sets of system model parameters and mainly con ...
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 ...
Tehnički vjesnik / Technical Gazette
(Strojarski fakultet u Slavonskom Brodu; Fakultet elektrotehnike, računarstva i informacijskih tehnologija Osijek; Građevinski i arhitektonski fakultet Osijek)
• 25 Jul 2019
Контрец, Наташа • Петровић, Милена • Панић, Стефан • Милошевић, Хранислав
The aim of this paper is to set framework for the repair rate in order to achieve required availability of a repairable system with alternating renewal process where the failure rate is Weibull distributed. In order to accomplish this goal, this paper proposes a novel model for a complete stochastic analysis of the repair rate. The resulting equation for probability density function of the repair rate enables precise modelling of the repair rate process for related values of availability and fai ...
REVUE ROUMAINE DES SCIENCES TECHNIQUES-SERIE ELECTROTECHNIQUE ET ENERGETIQUE
• 01 Apr 2024
Marković, Aleksandar • Perić, Zoran • Panić, Stefan • Spalević, Petar
In this paper, an approximation of the average bit error rate (ABER) probability expression, standard performance measure of wireless transmission over fading channels using linear spline functions with corresponding number of segments has been provided. Further, possible approximation improvement obtained by appliance of composite piecewise spline (combination of linear and quadratic) functions has also been analyzed. For the generality purpose multipath fading that occurs through the propagati ...
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 ...
(Hindawi)
• 03 Jan 2014
Valjarević, Aleksandar • Živković, Dragica • Valjarević, Dragana • Stevanović, Vladica • Golijanin, Jelena
The monitoring of the territory of Prokuplje Municipality was done based on 1 : 25,000 topographic maps in three different time periods (1969, 1974, and 1984) and land cover map in 2012. Analogous topographic maps done in 1969, 1974, and 1984 were used, while in 2012 the land cover map obtained by using CORINE-like approach was used. Topographic maps are developed by aerial campaign, and today they are replaced by satellite images. Topographic maps were scanned, and raster form was transformed t ...
The University Thought - Publication in Natural Sciences
• 30 Jun 2020
Milentijević, Nikola • Bačević, Nikola • Ristić, Dušan • Valjarević, Aleksandar • Pantelić, Milana • Kićović, Dušan
Recent climate changes cause significant natural and socio-economic consequences. They represent one of the major environmental problems of the late 20th and early 21st centuries. Changes in temperature and precipitation play a significant role in understanding climate change issues. They include numerous extreme climatic events such as heat waves, droughts, forest fires and more. Looking at regional differences in temperature and precipitation regime change, Southern Europe, including the Repub ...
IDŐJÁRÁS
(Hungarian Meteorological Service)
• 08 Mar 2022
Milentijević, Nikola • Valjarević, Aleksandar • Bačević, Nikola • Ristić, Dušan • Kalkan, Kristina • Cimbaljević, Marija • Dragojlović, Jovan • Savić, Stevan • Pantelić, Milana
Climate change is one of the largest environmental issues causing hydroclimatological extremes such as floods, droughts, and aridity. The aim of this study is to assess the observed and projected climate changes in Bačka (Serbia). Detailed trend analyses and possible climate scenarios over Bačka has not been presented up to now. In this paper, four data sets were extracted and calculated: mean annual air temperature, mean air temperatures during the vegetation period, mean annual precipitation a ...
Bulletin of Natural Sciences Research
(Faculty of Sciences and Mathematics, University of Priština in Kosovska Mitrovica, Republic of Serbia.)
• 01 Jan 2021
Najdanović, Marija • Maksimović, Miroslav • Velimirović, Ljubica
Infinitesimal bending of curves lying with a given precision on ruled surfaces in 3-dimensional Euclidean space is studied. In particular, the bending of curves on the cylinder, the hyperbolic paraboloid and the helicoid are considered and appropriate bending fields are found. Some examples are graphically presented.
The University Thought - Publication in Natural Sciences
• 01 Apr 2024
Maksimović, Miroslav • Jovanović, Tanja • Ljajko, Eugen • Ivanović, Milica
It is widely known that some surfaces contain special curves as a geodesics, while a lots of geodesics on surface have complicated shapes. Goal of this research is to find on what surfaces are u- and v- parameter curves geodesics. Developable surfaces that contain a given plane curve as a geodesic are studied in the article, whereas the plane curve is also an initial u-parameter curve on that surface. Parametric equations of the minimal surfaces that contain an epicycloid as a geodesic are also g ...
Facta Universitatis, Series: Mathematics and Informatics
• 01 Apr 2024
Maksimović, Miroslav • Stanković, Mića
In this paper, we have studied the second covariant derivative of Riemannian curvature tensor. Some new identities for the second covariant derivative have been given. Namely, identities obtained by cyclic sum with respect to three indices have been given. In the rst case, two curvature tensor indices and one covariant derivative index participate in the cyclic sum, while in the second case one curvature tensor index and two covariant derivative indices participate in the cyclic sum.
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.
Idȍjárás-Quarterly Journal of the Hungarian Meteorological Service
• 20 Jun 2021
Бачевић, Никола • Милентијевић, Никола • Ваљаревић, Александар • Гицић, Ајша • Кићовић, Душан • Радаковић, Милица • Николић, Милена • Пантелић, Милана
The paper presents trends for three categories of variables: average annual, average maximum and average minimum air temperatures. Data was provided by the meteorological yearbooks of the Republic Hydrometeorological Service of Serbia. The main goal of this paper is to detect possible temperature trends in Central Serbia. The trend equation, trend magnitude, and Mann-Kendall non-parametric test were used in the analysis of climate parameters. The used statistical methods were supplemented by GIS ...
Polish Journal of Environmental Studies
• 01 Oct 2021
Милентијевић, Никола • Остојић, Милош • Фекете, Рената • Калкан, Кристина • Ристић, Душан • Бачевић, Никола • Стевановић, Владица • Пантелић, Милана
Soil erosion assessment enables the identification of manifested soil erosion categories, their spatial distribution and the relationship between soil erosion and land use patterns. The integrated approach of the RUSLE method and GIS tools was used in estimating soil erosion rates in Bačka (Serbia). Previous research of soil erosion intensity in the study area was last performed 50 years ago. The spatial distribution of the calculated erosive factors shows the diversity of erosive conditions. Th ...
Open Geosciences
• 28 May 2021
Ваљаревић, Александар • Радовановић, Драган • Шошкић, Светислав • Бачевић, Никола • Милентијевић, Никола • Голијанин, Јелена • Ивановић, Марко
This paper points out the possibilities of better exploitation of marine traffic as well as its connection with other kinds of traffic. Special attention is given to the analysis of 1,081 harbors about their availability during the year. The methods and algorithms used in GIS are buffers, cluster, method of interpolations, and network analysis. The methods used for the purpose of conducting numerical analyses are algorithms that served for the analysis of the network, its transport features, and ...
Journal of the Geographical Institute "Jovan Cvijić"
• 25 Aug 2018
Милентијевић, Никола • Драгојловић, Јован • Ристић, Душан • Цимбаљевић, Марија • Демировић, Дуња • Ваљаревић, Александар
In the paper, the aridity is defined on the basis of four climate indices: De Martonne's index of aridity, Lang’s Rain Factor and Gračanin’s Rain factor for the vegetation period and hydrothermal coefficient of Seljaninov. While the annual value of the drought index (IDM) shows humid characteristics, the monthly values show the variability of the conditions. The summer months (July and August) are classified as semi-arid months, while the winter months (December- February) are extremely humid. T ...
