Slavica Ristic - Academia.edu (original) (raw)

Papers by Slavica Ristic

The monograph presents the results of perennial research of laser application in the cleaning of ... more The monograph presents the results of perennial research of laser application in the cleaning of undesirable layers on cultural heritage objects. Keeping in mind the priceless value of the items that have to be cleaned, research has been carried out with the aim of provide a scientifically based contribution to the safe and efficient application of lasers in conservation laboratories. Laser cleaning is a complex phenomenon that is followed by thermal, mechanical, optical, and chemical effects. Investigation of the laser light interaction with different materials is the first step in the process of successful laser application in the protection of cultural heritage objects. These processes depend on the characteristics of laser irradiation and materials characteristics. The results presented in this monograph included four types of lasers: Nd:YAG, CO2, Er:Glass and ruby laser. Laser irradiation parameters such as beam energy density (fluence), pulse length, number of pulses per secon...

Numerical simulation of 3D multiphase flow is performed to determine the velocity field in the fa... more Numerical simulation of 3D multiphase flow is performed to determine the velocity field in the fan mill. The mixture model of the Euler-Euler approach is used. Recirculating gas is a primary phase that carries granular phases including the coal powder and sand. The latter causes heavy wear of mill impact plates. The optimal form of hardfacing geometry and technology has an impact both on velocity magnitude and direction of flow in such a way as to reduce plate wear. This paper presents results of surface modification (based on numerical simulation), implemented on impact plates of the fan mill in the Kostolac B power plant in Serbia. Fishbone hardfacing is made in order to increase the lifetime of impact plates and extend the period between overhauls of fan mills. The experimental tests of fishbone surfacing plates, in exploitation conditions, show that the applied modification, hardfacing technologies and coating materials, give expected results. The application of this hardfacing ...

The paper presents the results of laser cleaning of corrosive and other deposits on a metal archa... more The paper presents the results of laser cleaning of corrosive and other deposits on a metal archaeological artefact from the Danube. Nd: YAG laser, energy up to 750 mJ and wavelengths λ = 1064 nm and 532 nm is used. The cleaning efficiency was examined in the function of laser energy, wavelength, and number of pulses, i.e. the time of exposure and moist of the surface of the sample. The results of removal of unwanted layers from the surface of the artefact and morphological changes on the base material were examined by optical and scanning electronic microscopy (OM and SEM). Micro-chemical changes have been determined by energy dispersive X-ray analysis (EDX) and x-ray fluorescence spectrometry (XRF). It has been shown that λ = 532 nm has higher efficiency for cleaning this sample and that the surface moisture has very small influence on laser cleaning efficiency. Research carried out on the archaeological object from the Danube shows that the application of lasers in the cleaning o...

Thermal Science, 2021

This paper presents a study of a free convection flow around the walls of a ventilation mill of t... more This paper presents a study of a free convection flow around the walls of a ventilation mill of the Thermal Power Plant ?Kostolac B?, Kostolac, Serbia. A combined method consists of thermography and software post-processing, PATS. The PATS is specially developed for recognition of turbulence zones by the custom processing of large input data sets from thermal videos. The calculations determine maximum temperature fluctuation i.e. peak-to-peak fluctuation at every spot during the recording time. Three thermal videos of the walls were analyzed. Maximum temperature fluctuation occurred in the zones close to the obstacles, which are thus recognized as one of the main sources of turbulence. Besides, PATS has recognized fine camera oscillations and mechanical movements of a flexible material near the dozer wall. The detected zones of turbulence correspond to the previous studies and to the theory. The method shows good potential in the field of free convective flow research through the im...

The application of 2D laser Doppler anemometry systems is considered, in the case of fluid flow c... more The application of 2D laser Doppler anemometry systems is considered, in the case of fluid flow confined in simple cylindrical and in cylindrical tube with flat external surface of the wall. Geometric optics laws are applied to the central lines of laser beams. Measurement volume dislocations, calibration angles and distances of measurement volume centre from the photo-detector field of view centre are expressed. The expressions derived in this paper were applied to specific turbulent swirl flow in pipe. That revealed several advantages of use of a simple cylindrical tube over nowadays favored use of cylindrical tube with flat external surface. Those results suggest that current avoiding of laser Doppler anemometry measurements with simple cylindrical tubes should be reconsidered.

Metallurgical and Materials Engineering, 2018

Corrosion behavior of metalized layers, obtained by Plasma Transferred Arc (PTA) process and by H... more Corrosion behavior of metalized layers, obtained by Plasma Transferred Arc (PTA) process and by High-Velocity Oxygen Fuel (HVOF) process with the purpose to improve the wear resistance of vital parts of ventilation mill in a thermal power plant, has been tested. The test is performed using three electrochemical techniques, in a solution containing chloride and sulfate ions. It is shown that the steel surface (base metal) dissolves uniformly, without pitting or other forms of local dissolution. Morphology of metalized layers surface indicates that dissolution is non-uniform, but it still can be considered as general corrosion. The corrosion rate of base metal and metalized layer obtained by PTA process is rather low, while the corrosion rate of the metalized layer obtained by HVOF process is much higher. Also, the difference in corrosion potentials between the base metal and the HVOF layer is pretty high but slightly less than maximum allowed difference (prescribed by the standard), ...

Tehnika, 2017

Laserske tehnike su postale nezamenjive u rešavanju najrazličitijih konzervatorskih problema. Zad... more Laserske tehnike su postale nezamenjive u rešavanju najrazličitijih konzervatorskih problema. Zadnjih tridesetak godina koriste se u procesu dijagnostike stanja, u procesu uklanjanja nepoželjnih slojeva, kao i u sanaciji oštećenja na predmetima kulturnog nasleđa. Zbog složenosti artefakata, tradicionalne metode čišćenja, u velikom broju slučajeva, imaju delimičnog uspeha. Lasersko čišćenje pokazuje određene prednosti kao što su: velika selektivnost, preciznost, efikasnost i pouzdanost u primeni kod različitih vrsta materijala. Postoje i određeni rizici po predmete čišćenja, te je optimizacija procesa predmet velikog broja istraživanja. U ovom radu su prikazani metodologija i rezultati primene infracrvene termografije za kontinualni monitoring raspodele temperature na površini metalnih objekta za vreme ozračavanja laserom. Izvršen je veliki broj eksperimenata, u kojima se Nd:YAG laser koristi za čišćenje. Dobijeni rezultati termogarfijom su verifikovani rezultatima numeričke simulacije širenja toplote u osnovnom materijalu. Pokazano je da se primenom infracrvene termografije mogu eliminisati oštećenja na osnovnom materijalu, što je od posebnog značaja kod artefakata neprocenjive vrednosti.

Thermal Science, 2018

Methods of diagnosing aerodynamic characteristics are constantly developing in order to conduct t... more Methods of diagnosing aerodynamic characteristics are constantly developing in order to conduct the precise and energy efficient wind tunnel testing of transport vehicles in the prototype design early stages. This is of a special importance when facing the time/cost consumption problems of detection of the transition zone over the simplified design of the high-speed train. Herein the applied thermodynamics found a very significant role in the field of experimental aerodynamics. With the intention of detecting the boundary-layer transition zone the following measurements were applied: the infrared thermography, flow visualization, and drag force measurements. In addition, the CFD was applied to predict the flow behaviour and transition zone, solving PDE consisting of the Reynolds-averaged Navier-Stokes equations, energy equation, and the equation of state for an ideal gas employing density-based solver. The thermal imaging defined the transition zone by simple application, and fast r...

Journal of Cultural Heritage, 2017

FME Transaction, 2016

Nowadays, the priority of food industry processes is based on mixing of the various flavour paste... more Nowadays, the priority of food industry processes is based on mixing of the various flavour pastes with the air. Optimal mixing process in the results means the instantaneous preparation of the homogenous and easily spreadable paste while consuming the lowest power. For achieving the brand precise and repeatable flavour, of major importance are, beside the filling parameters, the mixing setup parameters. This work presents the influence of rotation velocity, as one of the setup data, on: the paste quality and the mixing index, obtained by the CFD. The paste was prepared of soy flour and water, and described by the experimentally determined rheological characteristics. Mixing vessel, of the twin-shaft paddle type, introduced mixing by the laminar shear-thinning. This mixing process was modelled through 3D fully transient numerical simulations employing the volume of fluid (VOF) multiphase model of the Eulerian-Eulerian approach. In two cases, the influence of the angular velocity to the mixing-index value can be neglected. At the mixing area two regions were marked off. First one and dominant, was the region of active mixing preoccupied with high shear flow, described with high mixing index. Opposite, in the passive mixing region, the flow was almost rotational, represented by low mixing indexes. The rotation velocity change made the significant influence to wall shear stress levels achieving the highest values at the tips of the paddles.

FME Transaction, 2016

This paper presents results of the analyses obtained by numerical simulation for the possibilitie... more This paper presents results of the analyses obtained by numerical simulation for the possibilities of increasing the wear resistance of the ventilation mill working parts for coal grinding in the Kostolac B power plant. The possibilities for modification are based on 3D numerical simulation of multiphase flow of ventilation mill. Mineral materials during the process of milling in the ventilation mill cause strong wear of the suction plates. The multiphase flow simulations are performed in order to obtain the mineral materials paths and velocity vectors. The mixture model of the Euler-Euler approach is used. The results obtained in the numerical simulation serve for the selection of an optimal redesign of the suction plates. The application of this approach can reduce the number of possible repairs and extends the period between them, resulting in significant economic effects.

Vojnotehnički Glasnik, Feb 16, 2013

Infrared (IR) thermography, as a diagnostic technique, is used to find anomalies in the thermal s... more Infrared (IR) thermography, as a diagnostic technique, is used to find anomalies in the thermal signature of the Military museum building in Belgrade, to identify irregularities or deficiencies, such as wet materials, voids, or missing insulation and to inspect energy efficiency of the museum building and microclimatic indoor conditions. It is very important to perform preventative maintenance and stop undesirable environment influences that induce structural damage, modification of materials and agglomeration of pollutants and microorganisms on the cultural heritage artifacts, stored in the museum depot or exhibited in the galleries. The main causes for corrosion in historical buildings and museum artifacts are moisture and changeable temperature conditions. This paper deals with the results obtained in the application of IR thermography in determination of these conditions in the Military museum building, where very important metal artifacts are exhibited and deposed. The results show poor thermal insulation, wet walls and, generally, low energy efficiency.

Scientific Technical Review, 2015

Tehnika, 2015

Textile samples with metallic threads from the collection of the Ethnographic Museum Belgrade wer... more Textile samples with metallic threads from the collection of the Ethnographic Museum Belgrade were subjected to Nd:YAG laser irradiation in order to determinate certain parameters for successfully and safely clean corrosion products without degrading the surrounding material. Application of conventional cleaning methods did not give the expected results, and the implementation of laser technology was the next step. The Nd:YAG laser energy 150 mJ (1064 nm) and 50 mJ (532 nm) and pulse width 150 ps was used. The commercial, Thunder Art Laser was also used. Effects of the irradiated areas was investigated by optical and SEM microscopy and EDX analysis.

Zastita materijala, 2014

Primena lasera u čišćenju korozije na starim tekstilnim predmetima sa metalnim vezama Klаsične me... more Primena lasera u čišćenju korozije na starim tekstilnim predmetima sa metalnim vezama Klаsične metode čišćenjа starih tekstilnih predmeta sа metаlnim nitimа često puta ne dаje očekivаne rezultаte. Primenа lаserа u zaštiti i konzervaciji predmetа kulturne bаštine poslednjih godinа ima veliku ulogu. Nаjkomplikovаnijа je primenа lаserа u čišćenju eksponаtа koji imаju višekomponentni sаstаv, kаo što su, kombinаcije metаl-tekstil. U rаdu se razmatra problem koji se pojavio u fundusu tekstila Etnografskog muzeja u Beogradu. Prikаzаni su rezultаti ispitivаnjа efekаtа lаserskog čišćenjа na eksperimentalnim uzorcima etnografskog tekstila sа metаlnim nitimа. korišćenjem Nd:Yag lаsera. Ispitivаnje efekаtа čišćenja je vršeno optičkom i skenirаjućom elektonskom mikroskopijom i EDX аnаlizom. Određeni su pаrаmetri zа uspešno i bezbedno čišćenje korozionih produkаtа nа metаlnim nitimа, nа izabranim eksponatima.

Thermal Science, 2015

The level of pollution concentration to the archeological site Viminacium caused by the stack of ... more The level of pollution concentration to the archeological site Viminacium caused by the stack of Kostolac B power plant is analysed using CFD software. The wind is directed from the stack toward Viminacium-Archeological Site, Therma and Viminacium-Museum. Three different meteorological conditions resulting in fanning, fumigating, and looping plume are modelled. The temperature gradient as the most important factor defining the conditions of the atmosphere is included through the appropriate boundary conditions. It is shown that concentrations of the pollutants on the objects of Viminacium are very low. It can be attributed to the stack height and high temperature of the smoke at its exit. It also indicates that other sources of pollution such as open ash dumps and acid rain should be checked.

Vojnosanitetski pregled, 2014

Background/Aim. The cell line C6 is a continuous cell line of rat glioma and, as a transplantable... more Background/Aim. The cell line C6 is a continuous cell line of rat glioma and, as a transplantable line, is frequently used for induction into in vivo model of primary brain tumor. It is believed that, pursuant to its histological traits and biological behavior, this experimental tumor corresponds to human anaplastic astrocytoma of grade II/III, which is characterized by proliferative and invasive potency, and marked cell differentiation. The aim of this study was to determine macroscopic analysis of rat brain with implanted tumor during tumorigenesis, histological features of tumor cells of induced brain tumor and markers of proliferation (proliferation cell nuclear antigen - PCNA, cytokeratin - CK 19) and differentiation (glial fibrillary acidic protein -GFAP) in rat brain with implanted tumor. Methods. To determine histological structure of the brain with implanted C6 cells, we used brain sections stained for hematoxylin-eosin or kresyl violet, whereas other sections were immunohi...

Vojnotehnicki glasnik, 2013

Infrared (IR) thermography, as a diagnostic technique, is used to find anomalies in the thermal s... more Infrared (IR) thermography, as a diagnostic technique, is used to find anomalies in the thermal signature of the Military museum building in Belgrade, to identify irregularities or deficiencies, such as wet materials, voids, or missing insulation and to inspect energy efficiency of the museum building and microclimatic indoor conditions. It is very important to perform preventative maintenance and stop undesirable environment influences that induce structural damage, modification of materials and agglomeration of pollutants and microorganisms on the cultural heritage artifacts, stored in the museum depot or exhibited in the galleries. The main causes for corrosion in historical buildings and museum artifacts are moisture and changeable temperature conditions. This paper deals with the results obtained in the application of IR thermography in determination of these conditions in the Military museum building, where very important metal artifacts are exhibited and deposed. The results show poor thermal insulation, wet walls and, generally, low energy efficiency.

FME Transaction, 2014

This work presents the research results of the aerodynamic brake influence, mounted on the high-s... more This work presents the research results of the aerodynamic brake influence, mounted on the high-speed train's roof, on the flow field and overall braking force. The train consists of two locomotives at each end and four passenger cars between, with 121m of overall length. Aerodynamic brakes are designed to generate braking force by means of increasing the aerodynamic drag by opened panels over the train. Flow simulations were made by Fluent 12.1 software, for the train without and with one, two and three aerodynamic brakes, and velocities of 30, 50 and 70m/s. Drag force per unit panel area was determined as a function of train's velocity and the brake position. Contributions to train's gross braking force of each brake, obtained by simulations were: for first 24%, for second 15% and third 14.8%, and showed, also with panels' pressure distribution, good correlation with the aerodynamic drag calculations for flat plate orthogonally disposed to flow stream.

Vojnotehni?ki glasnik, 2011

U radu su dati osnovni principi rada PAT filtara, materijali i tehnologije primenjeni u njihovoj ... more U radu su dati osnovni principi rada PAT filtara, materijali i tehnologije primenjeni u njihovoj proizvodnji. Posebna pažnja posvećena je širokoj i raznovrsnoj primeni filtara s površinskim akustičkim talasom u procesiranju signala, telekomunikacijama i u oblasti hemijskih senzora, sa naglaskom na primene u vojne svrhe. Prikazan je originalni metod koji su autori razvili za modeliranje i predikciju karakteristika PAT filtara. Mogućnosti ovog metoda su ilustrovane na primeru hemijskih senzora za detekciju bojnih otrova. Projektovan je i izrađen PAT filtar PAT-FPO, koji je osnova za hemijski senzor specijalne namene.

The monograph presents the results of perennial research of laser application in the cleaning of ... more The monograph presents the results of perennial research of laser application in the cleaning of undesirable layers on cultural heritage objects. Keeping in mind the priceless value of the items that have to be cleaned, research has been carried out with the aim of provide a scientifically based contribution to the safe and efficient application of lasers in conservation laboratories. Laser cleaning is a complex phenomenon that is followed by thermal, mechanical, optical, and chemical effects. Investigation of the laser light interaction with different materials is the first step in the process of successful laser application in the protection of cultural heritage objects. These processes depend on the characteristics of laser irradiation and materials characteristics. The results presented in this monograph included four types of lasers: Nd:YAG, CO2, Er:Glass and ruby laser. Laser irradiation parameters such as beam energy density (fluence), pulse length, number of pulses per secon...

Numerical simulation of 3D multiphase flow is performed to determine the velocity field in the fa... more Numerical simulation of 3D multiphase flow is performed to determine the velocity field in the fan mill. The mixture model of the Euler-Euler approach is used. Recirculating gas is a primary phase that carries granular phases including the coal powder and sand. The latter causes heavy wear of mill impact plates. The optimal form of hardfacing geometry and technology has an impact both on velocity magnitude and direction of flow in such a way as to reduce plate wear. This paper presents results of surface modification (based on numerical simulation), implemented on impact plates of the fan mill in the Kostolac B power plant in Serbia. Fishbone hardfacing is made in order to increase the lifetime of impact plates and extend the period between overhauls of fan mills. The experimental tests of fishbone surfacing plates, in exploitation conditions, show that the applied modification, hardfacing technologies and coating materials, give expected results. The application of this hardfacing ...

The paper presents the results of laser cleaning of corrosive and other deposits on a metal archa... more The paper presents the results of laser cleaning of corrosive and other deposits on a metal archaeological artefact from the Danube. Nd: YAG laser, energy up to 750 mJ and wavelengths λ = 1064 nm and 532 nm is used. The cleaning efficiency was examined in the function of laser energy, wavelength, and number of pulses, i.e. the time of exposure and moist of the surface of the sample. The results of removal of unwanted layers from the surface of the artefact and morphological changes on the base material were examined by optical and scanning electronic microscopy (OM and SEM). Micro-chemical changes have been determined by energy dispersive X-ray analysis (EDX) and x-ray fluorescence spectrometry (XRF). It has been shown that λ = 532 nm has higher efficiency for cleaning this sample and that the surface moisture has very small influence on laser cleaning efficiency. Research carried out on the archaeological object from the Danube shows that the application of lasers in the cleaning o...

Thermal Science, 2021

This paper presents a study of a free convection flow around the walls of a ventilation mill of t... more This paper presents a study of a free convection flow around the walls of a ventilation mill of the Thermal Power Plant ?Kostolac B?, Kostolac, Serbia. A combined method consists of thermography and software post-processing, PATS. The PATS is specially developed for recognition of turbulence zones by the custom processing of large input data sets from thermal videos. The calculations determine maximum temperature fluctuation i.e. peak-to-peak fluctuation at every spot during the recording time. Three thermal videos of the walls were analyzed. Maximum temperature fluctuation occurred in the zones close to the obstacles, which are thus recognized as one of the main sources of turbulence. Besides, PATS has recognized fine camera oscillations and mechanical movements of a flexible material near the dozer wall. The detected zones of turbulence correspond to the previous studies and to the theory. The method shows good potential in the field of free convective flow research through the im...

The application of 2D laser Doppler anemometry systems is considered, in the case of fluid flow c... more The application of 2D laser Doppler anemometry systems is considered, in the case of fluid flow confined in simple cylindrical and in cylindrical tube with flat external surface of the wall. Geometric optics laws are applied to the central lines of laser beams. Measurement volume dislocations, calibration angles and distances of measurement volume centre from the photo-detector field of view centre are expressed. The expressions derived in this paper were applied to specific turbulent swirl flow in pipe. That revealed several advantages of use of a simple cylindrical tube over nowadays favored use of cylindrical tube with flat external surface. Those results suggest that current avoiding of laser Doppler anemometry measurements with simple cylindrical tubes should be reconsidered.

Metallurgical and Materials Engineering, 2018

Corrosion behavior of metalized layers, obtained by Plasma Transferred Arc (PTA) process and by H... more Corrosion behavior of metalized layers, obtained by Plasma Transferred Arc (PTA) process and by High-Velocity Oxygen Fuel (HVOF) process with the purpose to improve the wear resistance of vital parts of ventilation mill in a thermal power plant, has been tested. The test is performed using three electrochemical techniques, in a solution containing chloride and sulfate ions. It is shown that the steel surface (base metal) dissolves uniformly, without pitting or other forms of local dissolution. Morphology of metalized layers surface indicates that dissolution is non-uniform, but it still can be considered as general corrosion. The corrosion rate of base metal and metalized layer obtained by PTA process is rather low, while the corrosion rate of the metalized layer obtained by HVOF process is much higher. Also, the difference in corrosion potentials between the base metal and the HVOF layer is pretty high but slightly less than maximum allowed difference (prescribed by the standard), ...

Tehnika, 2017

Laserske tehnike su postale nezamenjive u rešavanju najrazličitijih konzervatorskih problema. Zad... more Laserske tehnike su postale nezamenjive u rešavanju najrazličitijih konzervatorskih problema. Zadnjih tridesetak godina koriste se u procesu dijagnostike stanja, u procesu uklanjanja nepoželjnih slojeva, kao i u sanaciji oštećenja na predmetima kulturnog nasleđa. Zbog složenosti artefakata, tradicionalne metode čišćenja, u velikom broju slučajeva, imaju delimičnog uspeha. Lasersko čišćenje pokazuje određene prednosti kao što su: velika selektivnost, preciznost, efikasnost i pouzdanost u primeni kod različitih vrsta materijala. Postoje i određeni rizici po predmete čišćenja, te je optimizacija procesa predmet velikog broja istraživanja. U ovom radu su prikazani metodologija i rezultati primene infracrvene termografije za kontinualni monitoring raspodele temperature na površini metalnih objekta za vreme ozračavanja laserom. Izvršen je veliki broj eksperimenata, u kojima se Nd:YAG laser koristi za čišćenje. Dobijeni rezultati termogarfijom su verifikovani rezultatima numeričke simulacije širenja toplote u osnovnom materijalu. Pokazano je da se primenom infracrvene termografije mogu eliminisati oštećenja na osnovnom materijalu, što je od posebnog značaja kod artefakata neprocenjive vrednosti.

Thermal Science, 2018

Methods of diagnosing aerodynamic characteristics are constantly developing in order to conduct t... more Methods of diagnosing aerodynamic characteristics are constantly developing in order to conduct the precise and energy efficient wind tunnel testing of transport vehicles in the prototype design early stages. This is of a special importance when facing the time/cost consumption problems of detection of the transition zone over the simplified design of the high-speed train. Herein the applied thermodynamics found a very significant role in the field of experimental aerodynamics. With the intention of detecting the boundary-layer transition zone the following measurements were applied: the infrared thermography, flow visualization, and drag force measurements. In addition, the CFD was applied to predict the flow behaviour and transition zone, solving PDE consisting of the Reynolds-averaged Navier-Stokes equations, energy equation, and the equation of state for an ideal gas employing density-based solver. The thermal imaging defined the transition zone by simple application, and fast r...

Journal of Cultural Heritage, 2017

FME Transaction, 2016

Nowadays, the priority of food industry processes is based on mixing of the various flavour paste... more Nowadays, the priority of food industry processes is based on mixing of the various flavour pastes with the air. Optimal mixing process in the results means the instantaneous preparation of the homogenous and easily spreadable paste while consuming the lowest power. For achieving the brand precise and repeatable flavour, of major importance are, beside the filling parameters, the mixing setup parameters. This work presents the influence of rotation velocity, as one of the setup data, on: the paste quality and the mixing index, obtained by the CFD. The paste was prepared of soy flour and water, and described by the experimentally determined rheological characteristics. Mixing vessel, of the twin-shaft paddle type, introduced mixing by the laminar shear-thinning. This mixing process was modelled through 3D fully transient numerical simulations employing the volume of fluid (VOF) multiphase model of the Eulerian-Eulerian approach. In two cases, the influence of the angular velocity to the mixing-index value can be neglected. At the mixing area two regions were marked off. First one and dominant, was the region of active mixing preoccupied with high shear flow, described with high mixing index. Opposite, in the passive mixing region, the flow was almost rotational, represented by low mixing indexes. The rotation velocity change made the significant influence to wall shear stress levels achieving the highest values at the tips of the paddles.

FME Transaction, 2016

This paper presents results of the analyses obtained by numerical simulation for the possibilitie... more This paper presents results of the analyses obtained by numerical simulation for the possibilities of increasing the wear resistance of the ventilation mill working parts for coal grinding in the Kostolac B power plant. The possibilities for modification are based on 3D numerical simulation of multiphase flow of ventilation mill. Mineral materials during the process of milling in the ventilation mill cause strong wear of the suction plates. The multiphase flow simulations are performed in order to obtain the mineral materials paths and velocity vectors. The mixture model of the Euler-Euler approach is used. The results obtained in the numerical simulation serve for the selection of an optimal redesign of the suction plates. The application of this approach can reduce the number of possible repairs and extends the period between them, resulting in significant economic effects.

Vojnotehnički Glasnik, Feb 16, 2013

Infrared (IR) thermography, as a diagnostic technique, is used to find anomalies in the thermal s... more Infrared (IR) thermography, as a diagnostic technique, is used to find anomalies in the thermal signature of the Military museum building in Belgrade, to identify irregularities or deficiencies, such as wet materials, voids, or missing insulation and to inspect energy efficiency of the museum building and microclimatic indoor conditions. It is very important to perform preventative maintenance and stop undesirable environment influences that induce structural damage, modification of materials and agglomeration of pollutants and microorganisms on the cultural heritage artifacts, stored in the museum depot or exhibited in the galleries. The main causes for corrosion in historical buildings and museum artifacts are moisture and changeable temperature conditions. This paper deals with the results obtained in the application of IR thermography in determination of these conditions in the Military museum building, where very important metal artifacts are exhibited and deposed. The results show poor thermal insulation, wet walls and, generally, low energy efficiency.

Scientific Technical Review, 2015

Tehnika, 2015

Textile samples with metallic threads from the collection of the Ethnographic Museum Belgrade wer... more Textile samples with metallic threads from the collection of the Ethnographic Museum Belgrade were subjected to Nd:YAG laser irradiation in order to determinate certain parameters for successfully and safely clean corrosion products without degrading the surrounding material. Application of conventional cleaning methods did not give the expected results, and the implementation of laser technology was the next step. The Nd:YAG laser energy 150 mJ (1064 nm) and 50 mJ (532 nm) and pulse width 150 ps was used. The commercial, Thunder Art Laser was also used. Effects of the irradiated areas was investigated by optical and SEM microscopy and EDX analysis.

Zastita materijala, 2014

Primena lasera u čišćenju korozije na starim tekstilnim predmetima sa metalnim vezama Klаsične me... more Primena lasera u čišćenju korozije na starim tekstilnim predmetima sa metalnim vezama Klаsične metode čišćenjа starih tekstilnih predmeta sа metаlnim nitimа često puta ne dаje očekivаne rezultаte. Primenа lаserа u zaštiti i konzervaciji predmetа kulturne bаštine poslednjih godinа ima veliku ulogu. Nаjkomplikovаnijа je primenа lаserа u čišćenju eksponаtа koji imаju višekomponentni sаstаv, kаo što su, kombinаcije metаl-tekstil. U rаdu se razmatra problem koji se pojavio u fundusu tekstila Etnografskog muzeja u Beogradu. Prikаzаni su rezultаti ispitivаnjа efekаtа lаserskog čišćenjа na eksperimentalnim uzorcima etnografskog tekstila sа metаlnim nitimа. korišćenjem Nd:Yag lаsera. Ispitivаnje efekаtа čišćenja je vršeno optičkom i skenirаjućom elektonskom mikroskopijom i EDX аnаlizom. Određeni su pаrаmetri zа uspešno i bezbedno čišćenje korozionih produkаtа nа metаlnim nitimа, nа izabranim eksponatima.

Thermal Science, 2015

The level of pollution concentration to the archeological site Viminacium caused by the stack of ... more The level of pollution concentration to the archeological site Viminacium caused by the stack of Kostolac B power plant is analysed using CFD software. The wind is directed from the stack toward Viminacium-Archeological Site, Therma and Viminacium-Museum. Three different meteorological conditions resulting in fanning, fumigating, and looping plume are modelled. The temperature gradient as the most important factor defining the conditions of the atmosphere is included through the appropriate boundary conditions. It is shown that concentrations of the pollutants on the objects of Viminacium are very low. It can be attributed to the stack height and high temperature of the smoke at its exit. It also indicates that other sources of pollution such as open ash dumps and acid rain should be checked.

Vojnosanitetski pregled, 2014

Background/Aim. The cell line C6 is a continuous cell line of rat glioma and, as a transplantable... more Background/Aim. The cell line C6 is a continuous cell line of rat glioma and, as a transplantable line, is frequently used for induction into in vivo model of primary brain tumor. It is believed that, pursuant to its histological traits and biological behavior, this experimental tumor corresponds to human anaplastic astrocytoma of grade II/III, which is characterized by proliferative and invasive potency, and marked cell differentiation. The aim of this study was to determine macroscopic analysis of rat brain with implanted tumor during tumorigenesis, histological features of tumor cells of induced brain tumor and markers of proliferation (proliferation cell nuclear antigen - PCNA, cytokeratin - CK 19) and differentiation (glial fibrillary acidic protein -GFAP) in rat brain with implanted tumor. Methods. To determine histological structure of the brain with implanted C6 cells, we used brain sections stained for hematoxylin-eosin or kresyl violet, whereas other sections were immunohi...

Vojnotehnicki glasnik, 2013

Infrared (IR) thermography, as a diagnostic technique, is used to find anomalies in the thermal s... more Infrared (IR) thermography, as a diagnostic technique, is used to find anomalies in the thermal signature of the Military museum building in Belgrade, to identify irregularities or deficiencies, such as wet materials, voids, or missing insulation and to inspect energy efficiency of the museum building and microclimatic indoor conditions. It is very important to perform preventative maintenance and stop undesirable environment influences that induce structural damage, modification of materials and agglomeration of pollutants and microorganisms on the cultural heritage artifacts, stored in the museum depot or exhibited in the galleries. The main causes for corrosion in historical buildings and museum artifacts are moisture and changeable temperature conditions. This paper deals with the results obtained in the application of IR thermography in determination of these conditions in the Military museum building, where very important metal artifacts are exhibited and deposed. The results show poor thermal insulation, wet walls and, generally, low energy efficiency.

FME Transaction, 2014

This work presents the research results of the aerodynamic brake influence, mounted on the high-s... more This work presents the research results of the aerodynamic brake influence, mounted on the high-speed train's roof, on the flow field and overall braking force. The train consists of two locomotives at each end and four passenger cars between, with 121m of overall length. Aerodynamic brakes are designed to generate braking force by means of increasing the aerodynamic drag by opened panels over the train. Flow simulations were made by Fluent 12.1 software, for the train without and with one, two and three aerodynamic brakes, and velocities of 30, 50 and 70m/s. Drag force per unit panel area was determined as a function of train's velocity and the brake position. Contributions to train's gross braking force of each brake, obtained by simulations were: for first 24%, for second 15% and third 14.8%, and showed, also with panels' pressure distribution, good correlation with the aerodynamic drag calculations for flat plate orthogonally disposed to flow stream.

Vojnotehni?ki glasnik, 2011

U radu su dati osnovni principi rada PAT filtara, materijali i tehnologije primenjeni u njihovoj ... more U radu su dati osnovni principi rada PAT filtara, materijali i tehnologije primenjeni u njihovoj proizvodnji. Posebna pažnja posvećena je širokoj i raznovrsnoj primeni filtara s površinskim akustičkim talasom u procesiranju signala, telekomunikacijama i u oblasti hemijskih senzora, sa naglaskom na primene u vojne svrhe. Prikazan je originalni metod koji su autori razvili za modeliranje i predikciju karakteristika PAT filtara. Mogućnosti ovog metoda su ilustrovane na primeru hemijskih senzora za detekciju bojnih otrova. Projektovan je i izrađen PAT filtar PAT-FPO, koji je osnova za hemijski senzor specijalne namene.