TY  - JOUR
AU  - Ilić, Jovan
AU  - Božić, Ivan
AU  - Petković, Aleksandar
AU  - Karadzić, Uroš
PY  - 2022
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/3776
AB  - Featured Application The newly developed model provides better understanding of the semi-pneumatic surge tanks and methods of application for the building and the refurbishment of the hydropower plant which is relatively simple, readily applicable and an inexpensive solution. Adopting adequate operational and safety measures is a significant part of the investigation of transient processes of hydropower plants (HPPs), both throughout the design stage of prospective plants and throughout the planning stage of the HPPs envisaged for refurbishment/uprating. One of the surge tank (ST) types, insufficiently researched so far, with a potential positive techno-economical influence, is the semi-pneumatic surge tank (SPST). Since the detailed analyses of SPST have never been performed or published before, the SPSTs have been examined here by presenting theoretical considerations, a newly developed mathematical model and comprehensive numerical simulations. The aim is to improve the performance of the open-air variations of STs. Multiple numerical simulations for a specific case-study HPP have been performed with the conclusions about the peculiarities and benefits of the SPST implementation. Firstly, numerical results for the existing as-built surge tank and corresponding alternative SPST have been compared, in order to verify the developed model. Variations of the main SPST constructive parameters have been analyzed, with the aim to determine the sensitivity of particular influences on transient processes versus its geometry alterations. The conducted analyses show that the SPST application brings HPP transient behaviour improvement compared to open-air ST. Dimensions of the new surge tank with specific aeration orifice could be smaller than the ones previously defined: both the diameter of the optimized upper and lower chamber and the core could be decreased by 20% and 12.5%, respectively.
PB  - MDPI, Basel
T2  - Applied Sciences-Basel
T1  - A Novel Approach to the Improvement of the Hydropower Plants Protective Measures-Modelling and Numerical Analyses of the Semi-Pneumatic Surge Tank
IS  - 5
VL  - 12
DO  - 10.3390/app12052353
ER  - 

@article{
author = "Ilić, Jovan and Božić, Ivan and Petković, Aleksandar and Karadzić, Uroš",
year = "2022",
abstract = "Featured Application The newly developed model provides better understanding of the semi-pneumatic surge tanks and methods of application for the building and the refurbishment of the hydropower plant which is relatively simple, readily applicable and an inexpensive solution. Adopting adequate operational and safety measures is a significant part of the investigation of transient processes of hydropower plants (HPPs), both throughout the design stage of prospective plants and throughout the planning stage of the HPPs envisaged for refurbishment/uprating. One of the surge tank (ST) types, insufficiently researched so far, with a potential positive techno-economical influence, is the semi-pneumatic surge tank (SPST). Since the detailed analyses of SPST have never been performed or published before, the SPSTs have been examined here by presenting theoretical considerations, a newly developed mathematical model and comprehensive numerical simulations. The aim is to improve the performance of the open-air variations of STs. Multiple numerical simulations for a specific case-study HPP have been performed with the conclusions about the peculiarities and benefits of the SPST implementation. Firstly, numerical results for the existing as-built surge tank and corresponding alternative SPST have been compared, in order to verify the developed model. Variations of the main SPST constructive parameters have been analyzed, with the aim to determine the sensitivity of particular influences on transient processes versus its geometry alterations. The conducted analyses show that the SPST application brings HPP transient behaviour improvement compared to open-air ST. Dimensions of the new surge tank with specific aeration orifice could be smaller than the ones previously defined: both the diameter of the optimized upper and lower chamber and the core could be decreased by 20% and 12.5%, respectively.",
publisher = "MDPI, Basel",
journal = "Applied Sciences-Basel",
title = "A Novel Approach to the Improvement of the Hydropower Plants Protective Measures-Modelling and Numerical Analyses of the Semi-Pneumatic Surge Tank",
number = "5",
volume = "12",
doi = "10.3390/app12052353"
}

Ilić, J., Božić, I., Petković, A.,& Karadzić, U.. (2022). A Novel Approach to the Improvement of the Hydropower Plants Protective Measures-Modelling and Numerical Analyses of the Semi-Pneumatic Surge Tank. in Applied Sciences-Basel
MDPI, Basel., 12(5).
https://doi.org/10.3390/app12052353

Ilić J, Božić I, Petković A, Karadzić U. A Novel Approach to the Improvement of the Hydropower Plants Protective Measures-Modelling and Numerical Analyses of the Semi-Pneumatic Surge Tank. in Applied Sciences-Basel. 2022;12(5).
doi:10.3390/app12052353 .

Ilić, Jovan, Božić, Ivan, Petković, Aleksandar, Karadzić, Uroš, "A Novel Approach to the Improvement of the Hydropower Plants Protective Measures-Modelling and Numerical Analyses of the Semi-Pneumatic Surge Tank" in Applied Sciences-Basel, 12, no. 5 (2022),
https://doi.org/10.3390/app12052353 . .

TY  - JOUR
AU  - Dragović, Branislav
AU  - Meštrović, Romeo
AU  - Zrnić, Nenad
AU  - Dragojević, Dražen
PY  - 2018
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2809
AB  - Pojam specifiičnog odnosa troškova odnosi se na razne tipove troškova broda i luke modelirane kao sistem reda čekanja Koristeći poznatu opštu formulu za specifični odnos troškova (označen sa R), izvodimo odgovarajući izraz za R u odnosu na M/Ek/1 model reda čekanja, gde je Ek (k = 2,3,...) Erlangova k - raspodela verovatnoće. Ovaj izraz nam omogućava da dobijemo teorijski rezultat koji se može primeniti za određivanje optimalnih vrednosti parametra oblika k od Ek uz data ograničenja u odnosu na druge performanse razmatranog lučkog modela teorije redova čekanja. Takođe su predstavljeni odgovarajući numerički i grafički rezultati. Dobijeni rezultati bi mogli biti korisni za buduća istraživanja razmatrane problematike.
AB  - The notion of specific cost ratio involves different type of costs of a ship and a port modeled as a queueing system. Using the known general formula for the specific cost ratio of arbitrary port queueing system (denoted as R), here we derive the related expression for R of the M/Ek/1 queue, where Ek (k = 2,3,...) is the Erlang- k probability distribution. This expression allows us to obtain a theoretical result which can be applied for determining the optimal values of shape parameter k of Ek under given constraints on other performances of the considered port queueing system. The related numerical and the graphical results are also presented. The obtained results would be a useful tool in future research in related subject areas.
PB  - Univerzitet u Beogradu - Mašinski fakultet, Beograd
T2  - FME Transactions
T1  - Modeliranje specifičnog odnosa troškova u luci sa M/Ek/1 modelom teorije redova čekanja
T1  - Specific cost ratio in a port modelling by M/Ek/1 queue
EP  - 359
IS  - 3
SP  - 355
VL  - 46
DO  - 10.5937/fmet1803355D
ER  - 

@article{
author = "Dragović, Branislav and Meštrović, Romeo and Zrnić, Nenad and Dragojević, Dražen",
year = "2018",
abstract = "Pojam specifiičnog odnosa troškova odnosi se na razne tipove troškova broda i luke modelirane kao sistem reda čekanja Koristeći poznatu opštu formulu za specifični odnos troškova (označen sa R), izvodimo odgovarajući izraz za R u odnosu na M/Ek/1 model reda čekanja, gde je Ek (k = 2,3,...) Erlangova k - raspodela verovatnoće. Ovaj izraz nam omogućava da dobijemo teorijski rezultat koji se može primeniti za određivanje optimalnih vrednosti parametra oblika k od Ek uz data ograničenja u odnosu na druge performanse razmatranog lučkog modela teorije redova čekanja. Takođe su predstavljeni odgovarajući numerički i grafički rezultati. Dobijeni rezultati bi mogli biti korisni za buduća istraživanja razmatrane problematike., The notion of specific cost ratio involves different type of costs of a ship and a port modeled as a queueing system. Using the known general formula for the specific cost ratio of arbitrary port queueing system (denoted as R), here we derive the related expression for R of the M/Ek/1 queue, where Ek (k = 2,3,...) is the Erlang- k probability distribution. This expression allows us to obtain a theoretical result which can be applied for determining the optimal values of shape parameter k of Ek under given constraints on other performances of the considered port queueing system. The related numerical and the graphical results are also presented. The obtained results would be a useful tool in future research in related subject areas.",
publisher = "Univerzitet u Beogradu - Mašinski fakultet, Beograd",
journal = "FME Transactions",
title = "Modeliranje specifičnog odnosa troškova u luci sa M/Ek/1 modelom teorije redova čekanja, Specific cost ratio in a port modelling by M/Ek/1 queue",
pages = "359-355",
number = "3",
volume = "46",
doi = "10.5937/fmet1803355D"
}

Dragović, B., Meštrović, R., Zrnić, N.,& Dragojević, D.. (2018). Modeliranje specifičnog odnosa troškova u luci sa M/Ek/1 modelom teorije redova čekanja. in FME Transactions
Univerzitet u Beogradu - Mašinski fakultet, Beograd., 46(3), 355-359.
https://doi.org/10.5937/fmet1803355D

Dragović B, Meštrović R, Zrnić N, Dragojević D. Modeliranje specifičnog odnosa troškova u luci sa M/Ek/1 modelom teorije redova čekanja. in FME Transactions. 2018;46(3):355-359.
doi:10.5937/fmet1803355D .

Dragović, Branislav, Meštrović, Romeo, Zrnić, Nenad, Dragojević, Dražen, "Modeliranje specifičnog odnosa troškova u luci sa M/Ek/1 modelom teorije redova čekanja" in FME Transactions, 46, no. 3 (2018):355-359,
https://doi.org/10.5937/fmet1803355D . .

TY  - JOUR
AU  - Meštrović, Romeo
AU  - Dragović, Branislav
AU  - Zrnić, Nenad
AU  - Dragojević, Dražen
PY  - 2018
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2969
AB  - U ovom radu razmatrani su grupni dolasci kontenera na kontenerskom skladištu koji su modelirani višekanalnim sistemom teorije redova čekanja MX/M/c sa c skladišnih dizalica kao kanalima opsluživanja. Pretpostavljeno je da je veličina grupe kontenera, X (broj kontenera y grupi koja dolazi na kontenersko skladište) distribuirana u skladu sa Puasonovskim tipom raspodele. Koristeći opšti izraz za razmatrani model redova čekanja, izveden je izraz za odnos specifičnih troškova koji sadrži verovatnoće stanja sistema, faktor iskorišćenja sistema, srednju vrednost i disperziju veličine grupe. Primenjujući taj izraz, predstavljeni su odgovarajući numerički i grafički rezultati za 1, 2 i 3 skladišne dizalice na kontenerskom skladištu u luci. Takođe ističemo da dobijeni analitički izraz omogućava diskusiju i poređenje vrednosti odnosa specifičnih troškova razmatranih modela redova čekanja MX/M/c sa različitim parametrima performanse luke, kao i poređenja istih sa odnosom specifičnih troškova u odnosu na redove čekanja istraživanih u prethodnim radovima autora koji se odnose na ovaj problem.
AB  - In this paper we consider batch arrivals of containers at a port container yard which is modeled as a multi-server queue MX/M/c with c yard cranes for the service. It is assumed that the related group size (the number of containers in an arriving group), X is distributed by a Poisson-like distribution. Using a more general formula for such queue models, here it is deduced the expression for the specific cost ratio involving the state probabilities, the utilization factor, the mean and the variance of the group size. Applying this expression, related numerical and graphical results are presented when the number of yard cranes at container yard in port is 1, 2 or 3. We also point out that this expression allows us to discuss and compare the values of specific cost ratio concerning the considered MX/M/c queues with different port performance parameters, as well as with specific cost ratio of the queues investigated in earlier authors' papers on this topic.
PB  - Univerzitet u Beogradu - Mašinski fakultet, Beograd
T2  - FME Transactions
T1  - Međuzavisnost različitih troškova modeliranja kontenerskih skladišta u luci primenom teorije redova čekanja
T1  - A relationship between different costs of container yard modelling in port using queuing approach
EP  - 373
IS  - 3
SP  - 367
VL  - 46
DO  - 10.5937/fmet1803367M
ER  - 

@article{
author = "Meštrović, Romeo and Dragović, Branislav and Zrnić, Nenad and Dragojević, Dražen",
year = "2018",
abstract = "U ovom radu razmatrani su grupni dolasci kontenera na kontenerskom skladištu koji su modelirani višekanalnim sistemom teorije redova čekanja MX/M/c sa c skladišnih dizalica kao kanalima opsluživanja. Pretpostavljeno je da je veličina grupe kontenera, X (broj kontenera y grupi koja dolazi na kontenersko skladište) distribuirana u skladu sa Puasonovskim tipom raspodele. Koristeći opšti izraz za razmatrani model redova čekanja, izveden je izraz za odnos specifičnih troškova koji sadrži verovatnoće stanja sistema, faktor iskorišćenja sistema, srednju vrednost i disperziju veličine grupe. Primenjujući taj izraz, predstavljeni su odgovarajući numerički i grafički rezultati za 1, 2 i 3 skladišne dizalice na kontenerskom skladištu u luci. Takođe ističemo da dobijeni analitički izraz omogućava diskusiju i poređenje vrednosti odnosa specifičnih troškova razmatranih modela redova čekanja MX/M/c sa različitim parametrima performanse luke, kao i poređenja istih sa odnosom specifičnih troškova u odnosu na redove čekanja istraživanih u prethodnim radovima autora koji se odnose na ovaj problem., In this paper we consider batch arrivals of containers at a port container yard which is modeled as a multi-server queue MX/M/c with c yard cranes for the service. It is assumed that the related group size (the number of containers in an arriving group), X is distributed by a Poisson-like distribution. Using a more general formula for such queue models, here it is deduced the expression for the specific cost ratio involving the state probabilities, the utilization factor, the mean and the variance of the group size. Applying this expression, related numerical and graphical results are presented when the number of yard cranes at container yard in port is 1, 2 or 3. We also point out that this expression allows us to discuss and compare the values of specific cost ratio concerning the considered MX/M/c queues with different port performance parameters, as well as with specific cost ratio of the queues investigated in earlier authors' papers on this topic.",
publisher = "Univerzitet u Beogradu - Mašinski fakultet, Beograd",
journal = "FME Transactions",
title = "Međuzavisnost različitih troškova modeliranja kontenerskih skladišta u luci primenom teorije redova čekanja, A relationship between different costs of container yard modelling in port using queuing approach",
pages = "373-367",
number = "3",
volume = "46",
doi = "10.5937/fmet1803367M"
}

Meštrović, R., Dragović, B., Zrnić, N.,& Dragojević, D.. (2018). Međuzavisnost različitih troškova modeliranja kontenerskih skladišta u luci primenom teorije redova čekanja. in FME Transactions
Univerzitet u Beogradu - Mašinski fakultet, Beograd., 46(3), 367-373.
https://doi.org/10.5937/fmet1803367M

Meštrović R, Dragović B, Zrnić N, Dragojević D. Međuzavisnost različitih troškova modeliranja kontenerskih skladišta u luci primenom teorije redova čekanja. in FME Transactions. 2018;46(3):367-373.
doi:10.5937/fmet1803367M .

Meštrović, Romeo, Dragović, Branislav, Zrnić, Nenad, Dragojević, Dražen, "Međuzavisnost različitih troškova modeliranja kontenerskih skladišta u luci primenom teorije redova čekanja" in FME Transactions, 46, no. 3 (2018):367-373,
https://doi.org/10.5937/fmet1803367M . .

TY  - JOUR
AU  - Sekularac, Milan B.
AU  - Janković, Novica
AU  - Vukoslavčević, Petar
PY  - 2017
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2620
AB  - To develop a reliable method for modeling fire case scenarios within the road tunnels and observing the effects of the skewed velocity, experimental and numerical approach is used. Experimental results obtained from a laboratory tunnel model installation, are used to define geometry and boundary conditions. The result for the overall ventilation performance is compared to the available cases, for empty tunnel and stationary bi-directional vehicle traffic. For a unidirectional traffic road tunnel, in traffic loaded conditions, with a ventilation system based on axial ducted fans, the numerical simulation is used to determine the flow and temperature fields, the ventilation efficiency (efficiency of momentum transfer), and to assess the shape of the velocity distribution. The effect that a skewed velocity distribution can have on the resulting thermal and pollutant fields (CO2), smoke backlayering and stratification, is evaluated using numerical simulations, for the model-scale tunnel fire conditions. The effect of two possible limiting shapes of the velocity distribution, dependent only on the location of the fire with respect to the nearest upstream operating fans, is analyzed. The numerical results for a fire are scenario are a starting point in assessing the feasibility of a laboratory model fire-scenario experiment, what is planned as the next step in this research.
PB  - Univerzitet u Beogradu - Institut za nuklearne nauke Vinča, Beograd
T2  - Thermal Science
T1  - Ventilation performance and pollutant flow in a unidirectional-traffic road tunnel
EP  - S794
SP  - S783
VL  - 21
DO  - 10.2298/TSCI160321117S
ER  - 

@article{
author = "Sekularac, Milan B. and Janković, Novica and Vukoslavčević, Petar",
year = "2017",
abstract = "To develop a reliable method for modeling fire case scenarios within the road tunnels and observing the effects of the skewed velocity, experimental and numerical approach is used. Experimental results obtained from a laboratory tunnel model installation, are used to define geometry and boundary conditions. The result for the overall ventilation performance is compared to the available cases, for empty tunnel and stationary bi-directional vehicle traffic. For a unidirectional traffic road tunnel, in traffic loaded conditions, with a ventilation system based on axial ducted fans, the numerical simulation is used to determine the flow and temperature fields, the ventilation efficiency (efficiency of momentum transfer), and to assess the shape of the velocity distribution. The effect that a skewed velocity distribution can have on the resulting thermal and pollutant fields (CO2), smoke backlayering and stratification, is evaluated using numerical simulations, for the model-scale tunnel fire conditions. The effect of two possible limiting shapes of the velocity distribution, dependent only on the location of the fire with respect to the nearest upstream operating fans, is analyzed. The numerical results for a fire are scenario are a starting point in assessing the feasibility of a laboratory model fire-scenario experiment, what is planned as the next step in this research.",
publisher = "Univerzitet u Beogradu - Institut za nuklearne nauke Vinča, Beograd",
journal = "Thermal Science",
title = "Ventilation performance and pollutant flow in a unidirectional-traffic road tunnel",
pages = "S794-S783",
volume = "21",
doi = "10.2298/TSCI160321117S"
}

Sekularac, M. B., Janković, N.,& Vukoslavčević, P.. (2017). Ventilation performance and pollutant flow in a unidirectional-traffic road tunnel. in Thermal Science
Univerzitet u Beogradu - Institut za nuklearne nauke Vinča, Beograd., 21, S783-S794.
https://doi.org/10.2298/TSCI160321117S

Sekularac MB, Janković N, Vukoslavčević P. Ventilation performance and pollutant flow in a unidirectional-traffic road tunnel. in Thermal Science. 2017;21:S783-S794.
doi:10.2298/TSCI160321117S .

Sekularac, Milan B., Janković, Novica, Vukoslavčević, Petar, "Ventilation performance and pollutant flow in a unidirectional-traffic road tunnel" in Thermal Science, 21 (2017):S783-S794,
https://doi.org/10.2298/TSCI160321117S . .