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282 results on '"Nikolić, Zoran"'

4. Machine Learning in Least-Squares Monte Carlo Proxy Modeling of Life Insurance Companies

Author

Krah, Anne-Sophie, Nikolić, Zoran, and Korn, Ralf

Subjects
Statistics - Methodology, Quantitative Finance - Risk Management, Statistics - Machine Learning
Abstract

Under the Solvency II regime, life insurance companies are asked to derive their solvency capital requirements from the full loss distributions over the coming year. Since the industry is currently far from being endowed with sufficient computational capacities to fully simulate these distributions, the insurers have to rely on suitable approximation techniques such as the least-squares Monte Carlo (LSMC) method. The key idea of LSMC is to run only a few wisely selected simulations and to process their output further to obtain a risk-dependent proxy function of the loss. In this paper, we present and analyze various adaptive machine learning approaches that can take over the proxy modeling task. The studied approaches range from ordinary and generalized least-squares regression variants over GLM and GAM methods to MARS and kernel regression routines. We justify the combinability of their regression ingredients in a theoretical discourse. Further, we illustrate the approaches in slightly disguised real-world experiments and perform comprehensive out-of-sample tests.

Published
2019

5. An Aspect of Optimal Regression Design for LSMC

Author

Weiß, Christian and Nikolić, Zoran

Subjects
Quantitative Finance - Computational Finance
Abstract

Practitioners sometimes suggest to use a combination of Sobol sequences and orthonormal polynomials when applying an LSMC algorithm for evaluation of option prices or in the context of risk capital calculation under the Solvency II regime. In this paper, we give a theoretical justification why good implementations of an LSMC algorithm should indeed combine these two features in order to assure numerical stability. Moreover, an explicit bound for the number of outer scenarios necessary to guarantee a prescribed degree of numerical stability is derived. We embed our observations into a coherent presentation of the theoretical background of LSMC in the insurance setting.

Published
2018

7. A Mathematical Model for Simulation of Intergranular μ-Capacitance as a Function of Neck Growth in Ceramic Sintering

Author

Randjelović, Branislav M., Nikolić, Zoran S., Pardalos, Panos M., Series Editor, Thai, My T., Series Editor, Du, Ding-Zhu, Honorary Editor, Belavkin, Roman V., Advisory Editor, Birge, John R., Advisory Editor, Butenko, Sergiy, Advisory Editor, Giannessi, Franco, Advisory Editor, Kumar, Vipin, Advisory Editor, Nagurney, Anna, Advisory Editor, Pei, Jun, Advisory Editor, Prokopyev, Oleg, Advisory Editor, Rebennack, Steffen, Advisory Editor, Resende, Mauricio, Advisory Editor, Terlaky, Tamás, Advisory Editor, Van, Vu, Advisory Editor, Xue, Guoliang, Advisory Editor, Ye, Yinyu, Advisory Editor, Daras, Nicholas J., editor, and Rassias, Themistocles M., editor

Published
2020
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8. Evaluacija slika neurona i astrocita glavnog maslinastog jedra čoveka - njihova analiza, klasifikacija i praćenje pomoću geometrijskih i fraktalnih parametara

Author

Rabasović, Mihailo D., Korenić, Andrej, Nikolić, Zoran, Radovanović, Saša, Ćirić, Darko, Stojić, Damjan, Rabasović, Mihailo D., Korenić, Andrej, Nikolić, Zoran, Radovanović, Saša, Ćirić, Darko, and Stojić, Damjan

Abstract

U regionu produžene moždine čoveka nalazi se glavno maslinasto jedro koje pripada donjem maslinastom kompleksu..., Within the region of the human’s medulla oblongata, the main contributor can be found int he section of the principal olivary nucleus as the central part of the Inferior olivary complex...

Published
2024

10. Estimation of the sky radiance

Author

Knežević Dragan, Nikolić Zoran, Mišković Katarina, and Vasiljević Darko

Subjects
infrared, sky, radiation, radiance, temperature, thermal imaging camera, uniformity, contrast, signature, atmosphere, skewness, kurtosis, Technology, Engineering (General). Civil engineering (General), TA1-2040
Abstract

For the infrared prefilter model there was a need for testing the sky radiation and defining its fluctuations within the zone of neighborhood area for the current frame and tests of repeatability. It was necessary to do the statistical processing of sky fluctuations in the current frame, because the sky is represented by corresponding layers through which the infrared image prefiltration is done. In this paper the uniformity for low elevation angles has been confirmed. The lower effective temperatures differences exist at large elevation angles.

Published
2019

14. Capillary liquid bridge and grain coarsening during liquid phase sintering

Author

Nikolić Zoran S. and Shinagawa Kazunari

Subjects
Liquid phase sintering, Coarsening, Liquid bridge, Simulation, Finite element method., Chemical technology, TP1-1185
Abstract

The finite element method is employed to simulate the microstructural evolution through grain coarsening within capillary liquid bridge. Liquid and solid phase domains will be represented with curved interfaces defined by the discrete set of points. Numerical method for simulation of grain coarsening will be based on the interfacial concentration as given by the Gibbs-Thomson equation and on modeling of intergrain diffusional interactions. It will be shown that the strong intergrain diffusional interactions can induce large shape distortion of multi grain model. Simulation of the grain coarsening for W-Ni alloy will be demonstrated as a first step. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. OI 172057]

Published
2017
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15. Revealing Self-organization of Granular Matter: From Fundamental Physics to Military Technology Applications

Author

Janković, Darko, Simović Pavlović, Marina, Pagnacco, Maja, Nikolić, Zoran, Bokić, Bojana, Kolarić, Branko, Tomić, Ljubiša, Vasiljević, Darko, Janković, Darko, Simović Pavlović, Marina, Pagnacco, Maja, Nikolić, Zoran, Bokić, Bojana, Kolarić, Branko, Tomić, Ljubiša, and Vasiljević, Darko

Abstract

Besides fundamental importance, granular physics has made considerable progress in revealing the dynamics of large ensembles of interacting macroscopic particles and their pattern formation for various applications in material, food, and chemical technologies. In this study, optical images obtained by the fast camera have been used to reveal the organization of various granular substrates as a function of interaction with projectiles of different shapes and energies. Specific patterns have been observed due to the energy dissipations after the impact. The obtained results indicate the possibility of manipulating granular matter to mold and direct/redirect the energy of the impact. This type of manipulation is of great importance for various applications, especially in the military domain.

Published
2023

16. Monitoring the Formation of Oxygen Bubble Patterns as a Forecast for Reaction Dynamics

Author

Pagnacco, Maja, Maksimović, Jelena, Potkonjak, Nebojša, Simović Pavlović, Marina, Nikolić, Zoran, Vasiljević, Darko, Kolarić, Branko, Pagnacco, Maja, Maksimović, Jelena, Potkonjak, Nebojša, Simović Pavlović, Marina, Nikolić, Zoran, Vasiljević, Darko, and Kolarić, Branko

Abstract

A non-equilibrium process, i.e., the state I (low concentration of iodide and iodine) to the state II (high concentration of iodide and iodine) transition, occurring after oscillatory Briggs-Rauscher reaction, was monitored by fast camera. The experiment's goal was not only to monitor the release of oxygen and the phase transition but also to use patterns formed by oxygen bubbles to get new insight into the kinetics of the process and the formation of solid iodine. To the best of our knowledge, it is the first time that an oxygen bubble pattern obtained by a fast camera has been used to analyze oscillatory system dynamics.

Published
2023

21. Multinational operations: Experiences that have a price

Author

Slavković Rade, Jukić Jadranko, and Nikolić Zoran

Subjects
multinational operations, experiences, development, parameter, calculation model, Military Science
Abstract

The participation of the Serbian Armed Forces in multinational operations is based on established security and defense needs and interests stated in the National Security Strategy of the Republic of Serbia, the Defense Strategy of the Republic of Serbia, and the Strategic Defense Review of the Republic of Serbia. Through the participation of members of the Serbian Armed Forces and other defense forces in multinational operations, our country confirms its interest and intention to concretely contribute to the global, European and regional security, and to the observance of international law and order, and thus it also fulfills the internationally accepted obligations arising from its membership of the UN and other international organizations. The members of the Serbian Armed Forces participating in multinational operations are richer in experiences and knowledge they accept from their co-workers from the armies of other participating countries, which they subsequently apply in carrying out their own regular tasks within their active duties, thus contributing to the development of military thinking, and consequently the operational art. Since their introduction, and particularly in recent years, the peacekeeping missions, recently referred to as peace support operations, have, due to their main characteristics (involvement of a large number of manpower and combat and non-combat weapons and equipment; major challenges faced by the participants of the mission; distance from their home country, etc.) become very expensive, both for the Organization of the United Nations (OUN) and the participating countries.

Published
2016
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27. The effect of disinfectants on dimensional stability of addition and condensation silicone impressions

Author

Sinobad Tamara, Obradović-Đuričić Kosovka, Nikolić Zoran, Dodić Slobodan, Lazić Vojkan, Sinobad Vladimir, and Jesenko-Rokvić Aleksandra

Subjects
dental impression materials, silicones, disinfectans, dental prosthesis, Medicine (General), R5-920
Abstract

Background/Aim. Dimensional stability and accuracy of an impression after chemical disinfection by immersion in disinfectants are crucial for the accuracy of final prosthetic restorations. The aim of this study was to assess the deformation of addition and condensation silicone impressions after disinfection in antimicrobial solutions. Methods. A total of 120 impressions were made on the model of the upper arch representing three full metal-ceramic crown preparations. Four impression materials were used: two condensation silicones (Oranwash L - Zhermack and Xantopren L Blue - Heraeus Kulzer) and two addition silicones (Elite H-D + regular body - Zhermack and Flexitime correct flow - Heraeus Kulzer). After removal from the model the impressions were immediately immersed in appropriate disinfectant (gluta-raldehyde, benzalkonium chloride - Sterigum and 5.25% NaOCl) for a period of 10 min. The control group consisted of samples that were not treated with disinfectant solution. Consecutive measurements of identical impressions were realized with a Canon G9 (12 megapixels, 2 fps, 6x/24x), and automated with a computer Asus Lamborghini VX-2R Intel C2D 2.4 GHz, by using Remote Capture software package, so that time-depending series of images of the same impression were obtained. Results. The dimensional changes of all the samples were significant both as a function of time and the applied disinfectant. The results show significant differences of the obtained dimensional changes between the group of condensation silicones and the group of addition silicones for the same time, and the same applied disinfectant (p = 0.026, F = 3.95). Conclusion. The greatest dimensional changes of addition and condensation silicone impressions appear in the first hour after their separation from the model.

Published
2014
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35. The effect of oxidation on structural and electrical properties of single wall carbon nanotubes

Author

Marković Zoran M., Peruško Davor B., Tošić Dragana D., Romčević Nebojša Z., Dramićanin Miroslav D., Nikolić Zoran M., and Marković Todorović Biljana M.

Subjects
single wall carbon nanotubes, atomic force microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, sheet resistance, Chemical technology, TP1-1185
Abstract

Single wall carbon nanotubes (SWCNTs) represent an important group of nanomaterials with attractive electrical, chemical, and mechanical properties. In this work we have investigated the structural, optical and electrical properties of single wall carbon nanotube films deposited on copper substrate and then transferred to polymethyl methacrylate (PMMA). The properties of deposited films were varied by changing different parameters: substrate temperature, deposition time and electric field strength. Atomic force microscopy (AFM) has been used to study the deposition process of SWCNT films on copper substrate. AFM analysis has shown that sodium dodecyl sulfate (SDS) micellas were deposited on copper substrate before carbon nanotubes because of their higher mobility. Raman spectroscopy revealed that SWCNTs deposited at elevated temperatures are oxidized. FTIR results showed that COOH groups and Cu2O were generated during electrophoretic process. The SWCNT films were transferred to PMMA substrate and they achieved a sheet resistance of 360 Ω/sq with 79% transparency at 550 nm wavelength and a strong adhesion to the substrate. The main reasons for higher values of sheet resistances of SWCNT thin films compared to those of other authors are oxidation of carbon nanotubes during electrophoresis and the presence of used surfactans in carbon matrix of deposited films.

Published
2011
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36. Optimizacija računarske analize morfologije epitelnih malignih plaža tumora dojke u cilju poboljšanja prognoze ishoda bolesti

Author

Milošević, Nebojša, Radulović, Marko, Nikolić, Zoran, Žikić, Dejan, Damjanović, Ana, Vraneš, Veličko, Milošević, Nebojša, Radulović, Marko, Nikolić, Zoran, Žikić, Dejan, Damjanović, Ana, and Vraneš, Veličko

Abstract

Napredak u preživljavanju i poboljšanju kvaliteta života pacijenata sa rakom dojke se može ostvariti personalizacijom terapije koja trenutno nije u punoj meri izvodljiva usled nedovoljne pouzdanosti prognostičkih pokazatelja. Ova teza je zato imala cilj da identifikuje izvore prognostičkih informacija i poboljša njihove prognostičke performanse na osnovu morfometrijskih osobina epitelnih malignih plaža, tj. malignih klastera u tumoru dojke i njihove ekspresije citokeratina. Obuhvaćeno je 102 pacijentkinje bez sistemske terapije koja bi uticala na pojavu metastaza. Analizirane su 532 slike histopatoloških preparata tumora bojenih koktelom AE1/AE3 pan-citokeratinskih antitela čime je omogućena vizualizacija epitelnih ćelija koje su kod karcinoma dojke najčešće maligno transformisane. Da bi se ispitao uticaj ekspresije citokeratina na prognostički učinak, izvršena je segmentacija slika na sedam nepreklapajućih opsega intenziteta piksela. Identifikaciji morfometrijskog profila (oblik, veličina, broj) malignih plaža sa najvećim prognostičkim značajem pristupilo se kombinacijom binarizacije slika sive skale sa šest pragova, pet filtera cirkularnosti i četiri filtera veličine. Tako je dobijeno 120 setova slika sa malignim plažama razdvojenim u odnosu na njihovu morfologiju. Prognostički učinak izračunatih parametara je utvrđen ROC analizom, a njihov značaj i nezavisnost su ispitani Cox regresionim modelom, koristeći pojavu udaljenih metastaza kao ishod bolesti. Značaj pojave metastaza je u tome što su metastaze, a ne primarni tumor, uzrok smrtnosti kod raka dojke. Rezultati su pokazali koncentraciju prognostičkog značaja u epitelnim malignim plažama sa povećanom cirkularnošću i manjom veličinom, koje eksprimiraju citokeratine u srednjem i niskom intenzitetu. Pri tome su plaže sa najboljim prognostičkim performansama (AUC = 0.82) identifikovane kao pojedinačne epitelne ćelije rasute po stromi tumora. Njihov broj je bio najefikasniji i nezavisan prognostički parametar. Izuze, Progress in the survival and life quality improvement of breast cancer patients could be achieved by personalized treatment, which is currently not fully achievable due to insufficient reliability of prognostic factors. This thesis aimed to identify sources of prognostic information and improve their prognostic performance based on the morphometric properties of epithelial malignant nests (i.e., malignant clusters) in breast tumor and their cytokeratin expression. 102 patients without systemic therapy that could affect the metastases occurrence were studied. 532 images of tumors tissue samples stained by the AE1/AE3 pan-cytokeratin antibody cocktail were analyzed, which enabled the visualization of epithelial cells that are most often malignantly transformed in breast cancer. To examine the effect of cytokeratin expression on prognostic efficiency, image segmentation was performed on seven non-overlapping pixel intensity ranges. The identification of the morphometric profile (shape, size, number) of malignant nests with the highest prognostic significance was accomplished applying six binarization thresholds in combination with five circularity filters and four size filters. Therefore, 120 sets of images were obtained with malignant nests separated based on their morphology. The prognostic performance of the extracted features was determined by ROC analysis, and their significance and independence were examined by Cox regression model, using distant metastasis occurrence as an endpoint event. The significance of metastasis occurrence is that metastasis, and not the primary tumor, is the cause of breast cancer mortality. The results showed that malignant epithelial nests with greater circularity, smaller size and with medium and low intensity of cytokeratin expression, are the most important for prognosis...

Published
2022

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Author

Kutlača, Đuro, Nedović, Viktor, Obradović, Vladimir, Nikolić, Zoran, Rakonjac, Ivan M., Živković, Lazar, Kutlača, Đuro, Nedović, Viktor, Obradović, Vladimir, Nikolić, Zoran, Rakonjac, Ivan M., and Živković, Lazar

Abstract

In order for science and technology policies to more effectively address the challenges related to insufficient academia-industry cooperation, which is still very present in the Republic of Serbia, it is necessary to gain a full understanding of different ways of interactions and types of cooperation between the two sectors. Research subject of this dissertation is the examination of the factors influencing the establishment and intensity of academia-industry cooperation in the Republic of Serbia, as well as the exploration of the structural characteristics of research and innovation networks. The main goal of the dissertation is to discover the main characteristics and examine the general patterns of academia-industry cooperation in the area of research and innovation. By using analysis and synthesis as research methods, the key factors that influence the academia-industry cooperation were identified, and by implementing regression analysis, their impact on the intensity of the academia-industry cooperation in the Republic of Serbia was examined. In addition, the results of social network analysis on the structural characteristics of networking showed that the academic sector has a central function in the network structure and has a crucial function in the process of knowledge transfer and information flows in research and innovation networks. The research conducted in this dissertation is an important step towards a better understanding of the academia-industry cooperation in the Republic of Serbia. In addition to the scientific contribution of the research results that are related to empirical validation and disproval of previous research results and theoretical contribution to the existing literature, the particular importance of the dissertation is reflected in the implementation of a new methodological approach to assess the intensity of the academia-industry cooperation which has significant potential for application in the field of science and innovation pol

Published
2022

38. Talasno prostiranje u gravitacionom polju: eksperimentalno istraživanje uticaja gravitacije na prostiranje pulsnih talasa kroz elastične cevi ispunjene viskoznim fluidom na biofizičkim modelima kardiovaskularnog sistema

Author

Žikić, Dejan, Mazić, Sanja, Belča, Ivan, Radovanović, Nebojša, Nikolić, Zoran, Stojadinović, Bojana S., Žikić, Dejan, Mazić, Sanja, Belča, Ivan, Radovanović, Nebojša, Nikolić, Zoran, and Stojadinović, Bojana S.

Abstract

Zbog porasta kardiovaskularnih bolesti u svetu, istraživanja su sve više usmerena na što precizniju medicinsku dijagnostiku ispitujući uzročnike kardiovaskularnih bolesti. Jedan od važnijih kardiovaskularnih parametara koji opisuje stanje krvnih sudova i daje veoma korisne informacije o stanju kardiovaskularnog sistema i njegovoj fiziološkoj starosti je brzina pulsnog talasa. Na brzinu prostiranja pulsnih talasa kroz kardiovaskularni sistem utiču različiti spoljašnji i unutrašnji faktori kao što su: viskoznost i gustina krvi, debljina i elastičnost krvnih sudova, gravitacija, dijastolni pritisak, položaj tela. TakoĎe, fizička aktivnost, razna fiziološka, akutna i patološka stanja mogu da dovedu do promene brzine prostiranja pulsnih talasa. Za istraživanje fenomena talasnog prostiranja krvi kroz kardiovaskularni sistem i ispitivanje uticaja spoljašnjih i unutrašnjih faktora na prostiranje talasa koriste se različite kompjuterske simulacije kao i biofizičko modelovanje. Istraživanja na modelima koja su do danas sprovedena nisu uzela u obzir uticaj gravitacije, unutrašnjeg pritiska i viskoznosti fluida na brzinu prostiranja pulsnog talasa. Glavni cilj ove disertacije je da se na biofizičkim modelima kardiovaskularnog sistema eksperimentalno odredi brzina prostiranja pulsnih talasa kroz elastične cevi ispunjene viskoznim fluidom u gravitacionom polju. Da bi istražili kako gravitacija utiče na brzinu pulsnog talasa, razvijena su dva biofizička modela kardiovaskularnog sistema koja simuliraju kretanje krvi u stojećem i ležećem položaju tela. TakoĎe, merene su brzine pulsnih talasa za tečnosti različite viskoznosti i gustine u elastičnim cevima različitog poluprečnika i debljine zida i pri različitim vrednostima pritiska unutar elastičnih cevi kroz koju se talas prostire. Dobijeni eksperimentalni rezultati pokazuju da postoje razlike u brzini prostiranja pulsnih talsa u smeru gravitacije u odnosu na suprotni smer. TakoĎe je pokazano da se sa promenom viskoznosti fluida, br, Due to the increase in cardiovascular diseases in the world, research is increasingly focused on the most accurate medical diagnostics by examining the causes of cardiovascular diseases. One of the most important cardiovascular parameters that describes the condition of blood vessels and gives very useful information about the condition of the cardiovascular system and its physiological age is the pulse wave velocity. The pulse wave velocity through the cardiovascular system is influenced by various external and internal factors such as: viscosity and density of blood, thickness and elasticity of blood vessels, gravity, diastolic pressure, body position. Also, physical activity, various physiological, acute and pathological conditions can lead to a change in the pulse wave velocity. Various computer simulations, as well as biophysical modeling, are used to investigate the phenomenon of blood wave propagation through the cardiovascular system and to examine the influence of external and internal factors on wave propagation. The research on the models that have been conducted so far has not considered the influence of gravity, internal pressure of fluid and viscosity on the pulse wave velocity. The main goal of this dissertation is to experimentally determine the pulse wave velocity through viscous fluid-filled elastic tubes in a gravitational field on biophysical models of the cardiovascular system. To investigate how gravity affects the pulse wave velocity, two biophysical models of the cardiovascular system have been developed that simulate the blood flow in the standing and lying position of the body. Pulse wave velocities were measured for fluids of different viscosities and densities in elastic tubes of different radius and wall thickness and at different values of fluid pressure. Experimental results show the existence of a difference in the velocities of pulse waves in the direction of gravity in relation to the opposite direction. It has been shown that as th

Published
2022

39. The analysis of damage threshold in the ruby laser interaction with copper and aluminium

Author

Katavić Boris T., Ristić Slavica S., Polić-Radovanović Suzana R., Nikolić Zoran N., Puharić Mirjana A., and Kutin Marina M.

Subjects
laser interaction, ruby laser, copper, aluminum, Chemical technology, TP1-1185
Abstract

Nondestructive methods are dominant in diagnosing the status and protection of all kinds of contemporary industrial object, as well as object of industrial heritage. Laser methods open wide possibilities of research in the field of diagnosis and metal processing. This paper presents the results of laser radiation interaction (wavelength λ = 694.3 nm, Ruby laser, Q-switch mode) with metal samples covered with a deposit. The goal of the examination was to determine the maximum energy density, that can be used in diagnostics purpouses (interferometric methods, 3D scanning, i.e.) and as a tool for safe removal of deposits, without interacting with the basic material. Microscopic examination performed with SEM coupled with EDX allowed the determination of the safe laser light energy density levels, which caused the removal of the deposite from the surface of the sample, without degradation of the surface. The energy density up to 20 103 J/m2 is maximum allowed for the diagnosis or deposit removal.

Published
2010
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48. Basic, extended and combined models for computer simulation of liquid phase sintering

Author

Nikolić Zoran S.

Subjects
liquid phase sintering, computer simulation, microstructure, grain boundary migration, Chemical technology, TP1-1185
Abstract

In this study, two-dimensional modeling of microstructural evolution during liquid phase sintering was considered. The simulation method developed is based on basic, extended and combined models defined for diffusion induced grain boundary migration.

Published
2002
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49. ONE APPROACH IN DISTANCE LEARNING INFORMATION SYSTEM DESIGNING

Author

Jerinić Srđan, Nikolić Milan, and Nikolić Zoran

Subjects
Businessprocesses, DistanceLearningSystem, E-learningresources, Technology, Mechanical engineering and machinery, TJ1-1570
Abstract

In this paper, the designing of business activities that take place within authorized platform of Distance Learning System – DLS, with the aim to improve the organization and achieve as better as possible teaching process in secondary education. Authorized DLS platform represents a dynamic interactive DLS Web application created in ASP.NET technology. Functional and information modelling was performed by application of IDEF method. Within DLS platform, there are multimedia e-learning resources, i.e. multimedia teaching units, which can be of different types: processing, determination or verification of knowledge. Performances of DLS application were analyzed and possibilities of further upgrade of DLS platform were considered.

Published
2014

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