Advanced analytical, numerical and analysis methods of applied fluid mechanics and complex systems

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Advanced analytical, numerical and analysis methods of applied fluid mechanics and complex systems (en)
Напредне аналитичке, нумеричке и методе анализе примењене механике флуида и комплексних система (sr)
Napredne analitičke, numeričke i metode analize primenjene mehanike fluida i kompleksnih sistema (sr_RS)
Authors

Publications

Functional Geometry of Human Connectomes

Tadić, Bosiljka; Anđelković, Miroslav; Melnik, Roderick

(2019)

TY  - JOUR
AU  - Tadić, Bosiljka
AU  - Anđelković, Miroslav
AU  - Melnik, Roderick
PY  - 2019
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/8451
AB  - Mapping the brain imaging data to networks, where nodes represent anatomical brain regions and edges indicate the occurrence of fiber tracts between them, has enabled an objective graph-theoretic analysis of human connectomes. However, the latent structure on higher-order interactions remains unexplored, where many brain regions act in synergy to perform complex functions. Here we use the simplicial complexes description of human connectome, where the shared simplexes encode higher-order relationships between groups of nodes. We study consensus connectome of 100 female (F-connectome) and of 100 male (M-connectome) subjects that we generated from the Budapest Reference Connectome Server v3.0 based on data from the Human Connectome Project. Our analysis reveals that the functional geometry of the common F&M-connectome coincides with the M-connectome and is characterized by a complex architecture of simplexes to the 14th order, which is built in six anatomical communities, and linked by short cycles. The F-connectome has additional edges that involve different brain regions, thereby increasing the size of simplexes and introducing new cycles. Both connectomes contain characteristic subjacent graphs that make them 3/2-hyperbolic. These results shed new light on the functional architecture of the brain, suggesting that insightful differences among connectomes are hidden in their higher-order connectivity. © 2019, The Author(s).
T2  - Scientific Reports
T1  - Functional Geometry of Human Connectomes
VL  - 9
IS  - 1
SP  - 12060
DO  - 10.1038/s41598-019-48568-5
ER  - 
@article{
author = "Tadić, Bosiljka and Anđelković, Miroslav and Melnik, Roderick",
year = "2019",
abstract = "Mapping the brain imaging data to networks, where nodes represent anatomical brain regions and edges indicate the occurrence of fiber tracts between them, has enabled an objective graph-theoretic analysis of human connectomes. However, the latent structure on higher-order interactions remains unexplored, where many brain regions act in synergy to perform complex functions. Here we use the simplicial complexes description of human connectome, where the shared simplexes encode higher-order relationships between groups of nodes. We study consensus connectome of 100 female (F-connectome) and of 100 male (M-connectome) subjects that we generated from the Budapest Reference Connectome Server v3.0 based on data from the Human Connectome Project. Our analysis reveals that the functional geometry of the common F&M-connectome coincides with the M-connectome and is characterized by a complex architecture of simplexes to the 14th order, which is built in six anatomical communities, and linked by short cycles. The F-connectome has additional edges that involve different brain regions, thereby increasing the size of simplexes and introducing new cycles. Both connectomes contain characteristic subjacent graphs that make them 3/2-hyperbolic. These results shed new light on the functional architecture of the brain, suggesting that insightful differences among connectomes are hidden in their higher-order connectivity. © 2019, The Author(s).",
journal = "Scientific Reports",
title = "Functional Geometry of Human Connectomes",
volume = "9",
number = "1",
pages = "12060",
doi = "10.1038/s41598-019-48568-5"
}
Tadić, B., Anđelković, M.,& Melnik, R.. (2019). Functional Geometry of Human Connectomes. in Scientific Reports, 9(1), 12060.
https://doi.org/10.1038/s41598-019-48568-5
Tadić B, Anđelković M, Melnik R. Functional Geometry of Human Connectomes. in Scientific Reports. 2019;9(1):12060.
doi:10.1038/s41598-019-48568-5 .
Tadić, Bosiljka, Anđelković, Miroslav, Melnik, Roderick, "Functional Geometry of Human Connectomes" in Scientific Reports, 9, no. 1 (2019):12060,
https://doi.org/10.1038/s41598-019-48568-5 . .
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Hidden geometries in networks arising from cooperative self-assembly

Suvakov, Milovan; Anđelković, Miroslav; Tadić, Bosiljka

(2018)

TY  - JOUR
AU  - Suvakov, Milovan
AU  - Anđelković, Miroslav
AU  - Tadić, Bosiljka
PY  - 2018
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/1931
AB  - Multilevel self-assembly involving small structured groups of nano-particles provides new routes to development of functional materials with a sophisticated architecture. Apart from the inter-particle forces, the geometrical shapes and compatibility of the building blocks are decisive factors. Therefore, a comprehensive understanding of these processes is essential for the design of assemblies of desired properties. Here, we introduce a computational model for cooperative self-assembly with the simultaneous attachment of structured groups of particles, which can be described by simplexes (connected pairs, triangles, tetrahedrons and higher order cliques) to a growing network. The model incorporates geometric rules that provide suitable nesting spaces for the new group and the chemical affinity of the system to accept excess particles. For varying chemical affinity, we grow different classes of assemblies by binding the cliques of distributed sizes. Furthermore, we characterize the emergent structures by metrics of graph theory and algebraic topology of graphs, and 4-point test for the intrinsic hyperbolicity of the networks. Our results show that higher Q-connectedness of the appearing simplicial complexes can arise due to only geometric factors and that it can be efficiently modulated by changing the chemical potential and the polydispersity of the binding simplexes.
T2  - Scientific Reports
T1  - Hidden geometries in networks arising from cooperative self-assembly
VL  - 8
DO  - 10.1038/s41598-018-20398-x
ER  - 
@article{
author = "Suvakov, Milovan and Anđelković, Miroslav and Tadić, Bosiljka",
year = "2018",
abstract = "Multilevel self-assembly involving small structured groups of nano-particles provides new routes to development of functional materials with a sophisticated architecture. Apart from the inter-particle forces, the geometrical shapes and compatibility of the building blocks are decisive factors. Therefore, a comprehensive understanding of these processes is essential for the design of assemblies of desired properties. Here, we introduce a computational model for cooperative self-assembly with the simultaneous attachment of structured groups of particles, which can be described by simplexes (connected pairs, triangles, tetrahedrons and higher order cliques) to a growing network. The model incorporates geometric rules that provide suitable nesting spaces for the new group and the chemical affinity of the system to accept excess particles. For varying chemical affinity, we grow different classes of assemblies by binding the cliques of distributed sizes. Furthermore, we characterize the emergent structures by metrics of graph theory and algebraic topology of graphs, and 4-point test for the intrinsic hyperbolicity of the networks. Our results show that higher Q-connectedness of the appearing simplicial complexes can arise due to only geometric factors and that it can be efficiently modulated by changing the chemical potential and the polydispersity of the binding simplexes.",
journal = "Scientific Reports",
title = "Hidden geometries in networks arising from cooperative self-assembly",
volume = "8",
doi = "10.1038/s41598-018-20398-x"
}
Suvakov, M., Anđelković, M.,& Tadić, B.. (2018). Hidden geometries in networks arising from cooperative self-assembly. in Scientific Reports, 8.
https://doi.org/10.1038/s41598-018-20398-x
Suvakov M, Anđelković M, Tadić B. Hidden geometries in networks arising from cooperative self-assembly. in Scientific Reports. 2018;8.
doi:10.1038/s41598-018-20398-x .
Suvakov, Milovan, Anđelković, Miroslav, Tadić, Bosiljka, "Hidden geometries in networks arising from cooperative self-assembly" in Scientific Reports, 8 (2018),
https://doi.org/10.1038/s41598-018-20398-x . .
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Origin of Hyperbolicity in Brain-to-Brain Coordination Networks

Tadić, Bosiljka; Anđelković, Miroslav; Suvakov, Milovan

(2018)

TY  - JOUR
AU  - Tadić, Bosiljka
AU  - Anđelković, Miroslav
AU  - Suvakov, Milovan
PY  - 2018
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/1953
AB  - Hyperbolicity or negative curvature of complex networks is the intrinsic geometric proximity of nodes in the graph metric space, which implies an improved network function. Here, we investigate hidden combinatorial geometries in brain-to-brain coordination networks arising through social communications. The networks originate from correlations among EEG signals previously recorded during spoken communications comprising of 14 individuals with 24 speaker-listener pairs. We find that the corresponding networks are delta-hyperbolic with delta(max) = 1 and the graph diameter D = 3 in each brain. While the emergent hyperbolicity in the two-brain networks varies satisfying delta(max)/D/2 LT = 1 and can be attributed to the topology of the subgraph formed around the cross-brains linking channels. We identify these subgraphs in each studied two-brain network and decompose their structure into simple geometric descriptors ( triangles, tetrahedra and cliques of higher orders) that contribute to hyperbolicity. Considering topologies that exceed two separate brain networks as a measure of coordination synergy between the brains, we identify different neural correlation patterns ranging from weak coordination to super-brain structure. These topology features are in qualitative agreement with the listeners self-reported ratings of own experience and quality of the speaker, suggesting that studies of the cross-brain connector networks can reveal new insight into the neural mechanisms underlying human social behavior.
T2  - Frontiers in Physics
T1  - Origin of Hyperbolicity in Brain-to-Brain Coordination Networks
VL  - 6
DO  - 10.3389/fphy.2018.00007
ER  - 
@article{
author = "Tadić, Bosiljka and Anđelković, Miroslav and Suvakov, Milovan",
year = "2018",
abstract = "Hyperbolicity or negative curvature of complex networks is the intrinsic geometric proximity of nodes in the graph metric space, which implies an improved network function. Here, we investigate hidden combinatorial geometries in brain-to-brain coordination networks arising through social communications. The networks originate from correlations among EEG signals previously recorded during spoken communications comprising of 14 individuals with 24 speaker-listener pairs. We find that the corresponding networks are delta-hyperbolic with delta(max) = 1 and the graph diameter D = 3 in each brain. While the emergent hyperbolicity in the two-brain networks varies satisfying delta(max)/D/2 LT = 1 and can be attributed to the topology of the subgraph formed around the cross-brains linking channels. We identify these subgraphs in each studied two-brain network and decompose their structure into simple geometric descriptors ( triangles, tetrahedra and cliques of higher orders) that contribute to hyperbolicity. Considering topologies that exceed two separate brain networks as a measure of coordination synergy between the brains, we identify different neural correlation patterns ranging from weak coordination to super-brain structure. These topology features are in qualitative agreement with the listeners self-reported ratings of own experience and quality of the speaker, suggesting that studies of the cross-brain connector networks can reveal new insight into the neural mechanisms underlying human social behavior.",
journal = "Frontiers in Physics",
title = "Origin of Hyperbolicity in Brain-to-Brain Coordination Networks",
volume = "6",
doi = "10.3389/fphy.2018.00007"
}
Tadić, B., Anđelković, M.,& Suvakov, M.. (2018). Origin of Hyperbolicity in Brain-to-Brain Coordination Networks. in Frontiers in Physics, 6.
https://doi.org/10.3389/fphy.2018.00007
Tadić B, Anđelković M, Suvakov M. Origin of Hyperbolicity in Brain-to-Brain Coordination Networks. in Frontiers in Physics. 2018;6.
doi:10.3389/fphy.2018.00007 .
Tadić, Bosiljka, Anđelković, Miroslav, Suvakov, Milovan, "Origin of Hyperbolicity in Brain-to-Brain Coordination Networks" in Frontiers in Physics, 6 (2018),
https://doi.org/10.3389/fphy.2018.00007 . .
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Quantifying self-organization in fusion plasmas

Rajković, Milan; Milovanović, M.; Škorić, Miloš M.

(2017)

TY  - JOUR
AU  - Rajković, Milan
AU  - Milovanović, M.
AU  - Škorić, Miloš M.
PY  - 2017
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/1555
AB  - A multifaceted framework for understanding self-organization in fusion plasma dynamics is presented which concurrently manages several important issues related to the nonlinear and multiscale phenomena involved, namely,(1) it chooses the optimal template wavelet for the analysis of temporal or spatio-temporal plasma dynamics, (2) it detects parameter values at which bifurcations occur, (3) it quantifies complexity and self-organization, (4) it enables short-term prediction of nonlinear dynamics, and (5) it extracts coherent structures in turbulence by separating them from the incoherent component. The first two aspects including the detection of changes in the dynamics of a nonlinear system are illustrated by analyzing Stimulated Raman Scattering in a bounded, weakly dissipative plasma. Self-organization in the fusion plasma is quantitatively analyzed based on the numerical simulations of the Gyrokinetic-Vlasov (GKV) model of plasma dynamics. The parameters for the standard and inward shifted magnetic configurations, relevant for the Large Helical Device, were used in order to quantitatively compare self-organization and complexity in the two configurations. Finally, self-organization is analyzed for three different confinement regimes of the MAST device. Published by AIP Publishing.
T2  - Physics of Plasmas
T1  - Quantifying self-organization in fusion plasmas
VL  - 24
IS  - 5
DO  - 10.1063/1.4982612
ER  - 
@article{
author = "Rajković, Milan and Milovanović, M. and Škorić, Miloš M.",
year = "2017",
abstract = "A multifaceted framework for understanding self-organization in fusion plasma dynamics is presented which concurrently manages several important issues related to the nonlinear and multiscale phenomena involved, namely,(1) it chooses the optimal template wavelet for the analysis of temporal or spatio-temporal plasma dynamics, (2) it detects parameter values at which bifurcations occur, (3) it quantifies complexity and self-organization, (4) it enables short-term prediction of nonlinear dynamics, and (5) it extracts coherent structures in turbulence by separating them from the incoherent component. The first two aspects including the detection of changes in the dynamics of a nonlinear system are illustrated by analyzing Stimulated Raman Scattering in a bounded, weakly dissipative plasma. Self-organization in the fusion plasma is quantitatively analyzed based on the numerical simulations of the Gyrokinetic-Vlasov (GKV) model of plasma dynamics. The parameters for the standard and inward shifted magnetic configurations, relevant for the Large Helical Device, were used in order to quantitatively compare self-organization and complexity in the two configurations. Finally, self-organization is analyzed for three different confinement regimes of the MAST device. Published by AIP Publishing.",
journal = "Physics of Plasmas",
title = "Quantifying self-organization in fusion plasmas",
volume = "24",
number = "5",
doi = "10.1063/1.4982612"
}
Rajković, M., Milovanović, M.,& Škorić, M. M.. (2017). Quantifying self-organization in fusion plasmas. in Physics of Plasmas, 24(5).
https://doi.org/10.1063/1.4982612
Rajković M, Milovanović M, Škorić MM. Quantifying self-organization in fusion plasmas. in Physics of Plasmas. 2017;24(5).
doi:10.1063/1.4982612 .
Rajković, Milan, Milovanović, M., Škorić, Miloš M., "Quantifying self-organization in fusion plasmas" in Physics of Plasmas, 24, no. 5 (2017),
https://doi.org/10.1063/1.4982612 . .
1
1
1

Algebraic Topology of Multi-Brain Connectivity Networks Reveals Dissimilarity in Functional Patterns during Spoken Communications

Tadić, Bosiljka; Anđelković, Miroslav; Boshkoska, Biljana Mileva; Levnajić, Zoran

(2016)

TY  - JOUR
AU  - Tadić, Bosiljka
AU  - Anđelković, Miroslav
AU  - Boshkoska, Biljana Mileva
AU  - Levnajić, Zoran
PY  - 2016
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/1322
AB  - Human behaviour in various circumstances mirrors the corresponding brain connectivity patterns, which are suitably represented by functional brain networks. While the objective analysis of these networks by graph theory tools deepened our understanding of brain functions, the multi-brain structures and connections underlying human social behaviour remain largely unexplored. In this study, we analyse the aggregate graph that maps coordination of EEG signals previously recorded during spoken communications in two groups of six listeners and two speakers. Applying an innovative approach based on the algebraic topology of graphs, we analyse higher-order topological complexes consisting of mutually interwoven cliques of a high order to which the identified functional connections organise. Our results reveal that the topological quantifiers provide new suitable measures for differences in the brain activity patterns and inter-brain synchronisation between speakers and listeners. Moreover, the higher topological complexity correlates with the listeners concentration to the story, confirmed by self-rating, and closeness to the speakers brain activity pattern, which is measured by network-to-network distance. The connectivity structures of the frontal and parietal lobe consistently constitute distinct clusters, which extend across the listeners group. Formally, the topology quantifiers of the multi-brain communities exceed the sum of those of the participating individuals and also reflect the listeners rated attributes of the speaker and the narrated subject. In the broader context, the presented study exposes the relevance of higher topological structures ( besides standard graph measures) for characterising functional brain networks under different stimuli.
T2  - PLOS One
T1  - Algebraic Topology of Multi-Brain Connectivity Networks Reveals Dissimilarity in Functional Patterns during Spoken Communications
VL  - 11
IS  - 11
DO  - 10.1371/journal.pone.0166787
ER  - 
@article{
author = "Tadić, Bosiljka and Anđelković, Miroslav and Boshkoska, Biljana Mileva and Levnajić, Zoran",
year = "2016",
abstract = "Human behaviour in various circumstances mirrors the corresponding brain connectivity patterns, which are suitably represented by functional brain networks. While the objective analysis of these networks by graph theory tools deepened our understanding of brain functions, the multi-brain structures and connections underlying human social behaviour remain largely unexplored. In this study, we analyse the aggregate graph that maps coordination of EEG signals previously recorded during spoken communications in two groups of six listeners and two speakers. Applying an innovative approach based on the algebraic topology of graphs, we analyse higher-order topological complexes consisting of mutually interwoven cliques of a high order to which the identified functional connections organise. Our results reveal that the topological quantifiers provide new suitable measures for differences in the brain activity patterns and inter-brain synchronisation between speakers and listeners. Moreover, the higher topological complexity correlates with the listeners concentration to the story, confirmed by self-rating, and closeness to the speakers brain activity pattern, which is measured by network-to-network distance. The connectivity structures of the frontal and parietal lobe consistently constitute distinct clusters, which extend across the listeners group. Formally, the topology quantifiers of the multi-brain communities exceed the sum of those of the participating individuals and also reflect the listeners rated attributes of the speaker and the narrated subject. In the broader context, the presented study exposes the relevance of higher topological structures ( besides standard graph measures) for characterising functional brain networks under different stimuli.",
journal = "PLOS One",
title = "Algebraic Topology of Multi-Brain Connectivity Networks Reveals Dissimilarity in Functional Patterns during Spoken Communications",
volume = "11",
number = "11",
doi = "10.1371/journal.pone.0166787"
}
Tadić, B., Anđelković, M., Boshkoska, B. M.,& Levnajić, Z.. (2016). Algebraic Topology of Multi-Brain Connectivity Networks Reveals Dissimilarity in Functional Patterns during Spoken Communications. in PLOS One, 11(11).
https://doi.org/10.1371/journal.pone.0166787
Tadić B, Anđelković M, Boshkoska BM, Levnajić Z. Algebraic Topology of Multi-Brain Connectivity Networks Reveals Dissimilarity in Functional Patterns during Spoken Communications. in PLOS One. 2016;11(11).
doi:10.1371/journal.pone.0166787 .
Tadić, Bosiljka, Anđelković, Miroslav, Boshkoska, Biljana Mileva, Levnajić, Zoran, "Algebraic Topology of Multi-Brain Connectivity Networks Reveals Dissimilarity in Functional Patterns during Spoken Communications" in PLOS One, 11, no. 11 (2016),
https://doi.org/10.1371/journal.pone.0166787 . .
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22
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The influence of architecture of nanoparticle networks on collective charge transport revealed by the fractal time series and topology of phase space manifolds

Tadić, Bosiljka; Anđelković, Miroslav; Šuvakov, Milovan

(2016)

TY  - JOUR
AU  - Tadić, Bosiljka
AU  - Anđelković, Miroslav
AU  - Šuvakov, Milovan
PY  - 2016
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/1243
AB  - Charge transport in the Coulomb blockade regime of two-dimensional nanoparticle arrays exhibits nonlinear I-V characteristics, where the level of nonlinearity strongly associates with the arrays architecture. Here, we use different mathematical techniques to investigate the collective behavior of the charge transport and quantify its relationship to the structure of the nanoparticle assembly. First, we simulate single-electron tunneling conduction in a class of nanoparticle networks with a controlled variation of the structural characteristics (branching, extended linear segments) which influence the local communication among the conducting paths between the electrodes. Further, by applying an innovative approach based on the algebraic topology of graphs, we analyze the structure of connections in the manifolds, which map the fractal time series of charge fluctuations in the phase space. By tracking the I-V curves in different nanoparticle networks together with the indicators of collective dynamics and the topology of the phase space manifolds, we show that the increased I-V nonlinearity is fully consistent with the enhanced aggregate fluctuations and higher connection complexity among the participating states. Also, by determining shifts in the topology and cooperative transport features, we explore the impact of the size of electrodes and local charge disorder. The results are relevant for designing the nanoparticle devices with improved conduction; they also highlight the significance of topological descriptions for a broader understanding of the nature of fluctuations at the nanoscale.
T2  - Journal of Coupled Systems and Multiscale Dynamics
T1  - The influence of architecture of nanoparticle networks on collective charge transport revealed by the fractal time series and topology of phase space manifolds
VL  - 4
IS  - 1
SP  - 30
EP  - 42
DO  - 10.1166/jcsmd.2016.1094
ER  - 
@article{
author = "Tadić, Bosiljka and Anđelković, Miroslav and Šuvakov, Milovan",
year = "2016",
abstract = "Charge transport in the Coulomb blockade regime of two-dimensional nanoparticle arrays exhibits nonlinear I-V characteristics, where the level of nonlinearity strongly associates with the arrays architecture. Here, we use different mathematical techniques to investigate the collective behavior of the charge transport and quantify its relationship to the structure of the nanoparticle assembly. First, we simulate single-electron tunneling conduction in a class of nanoparticle networks with a controlled variation of the structural characteristics (branching, extended linear segments) which influence the local communication among the conducting paths between the electrodes. Further, by applying an innovative approach based on the algebraic topology of graphs, we analyze the structure of connections in the manifolds, which map the fractal time series of charge fluctuations in the phase space. By tracking the I-V curves in different nanoparticle networks together with the indicators of collective dynamics and the topology of the phase space manifolds, we show that the increased I-V nonlinearity is fully consistent with the enhanced aggregate fluctuations and higher connection complexity among the participating states. Also, by determining shifts in the topology and cooperative transport features, we explore the impact of the size of electrodes and local charge disorder. The results are relevant for designing the nanoparticle devices with improved conduction; they also highlight the significance of topological descriptions for a broader understanding of the nature of fluctuations at the nanoscale.",
journal = "Journal of Coupled Systems and Multiscale Dynamics",
title = "The influence of architecture of nanoparticle networks on collective charge transport revealed by the fractal time series and topology of phase space manifolds",
volume = "4",
number = "1",
pages = "30-42",
doi = "10.1166/jcsmd.2016.1094"
}
Tadić, B., Anđelković, M.,& Šuvakov, M.. (2016). The influence of architecture of nanoparticle networks on collective charge transport revealed by the fractal time series and topology of phase space manifolds. in Journal of Coupled Systems and Multiscale Dynamics, 4(1), 30-42.
https://doi.org/10.1166/jcsmd.2016.1094
Tadić B, Anđelković M, Šuvakov M. The influence of architecture of nanoparticle networks on collective charge transport revealed by the fractal time series and topology of phase space manifolds. in Journal of Coupled Systems and Multiscale Dynamics. 2016;4(1):30-42.
doi:10.1166/jcsmd.2016.1094 .
Tadić, Bosiljka, Anđelković, Miroslav, Šuvakov, Milovan, "The influence of architecture of nanoparticle networks on collective charge transport revealed by the fractal time series and topology of phase space manifolds" in Journal of Coupled Systems and Multiscale Dynamics, 4, no. 1 (2016):30-42,
https://doi.org/10.1166/jcsmd.2016.1094 . .
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10

Topology of Innovation Spaces in the Knowledge Networks Emerging through Questions-And-Answers

Anđelković, Miroslav; Tadić, Bosiljka; Mitrović Dankulov, Marija; Rajković, Milan; Melnik, Roderick

(2016)

TY  - JOUR
AU  - Anđelković, Miroslav
AU  - Tadić, Bosiljka
AU  - Mitrović Dankulov, Marija
AU  - Rajković, Milan
AU  - Melnik, Roderick
PY  - 2016
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/1085
AB  - The communication processes of knowledge creation represent a particular class of human dynamics where the expertise of individuals plays a substantial role, thus offering a unique possibility to study the structure of knowledge networks from online data. Here, we use the empirical evidence from questions-and-answers in mathematics to analyse the emergence of the network of knowledge contents (or tags) as the individual experts use them in the process. After removing extra edges from the network-associated graph, we apply the methods of algebraic topology of graphs to examine the structure of higher-order combinatorial spaces in networks for four consecutive time intervals. We find that the ranking distributions of the suitably scaled topological dimensions of nodes fall into a unique curve for all time intervals and filtering levels, suggesting a robust architecture of knowledge networks. Moreover, these networks preserve the logical structure of knowledge within emergent communities of nodes, labeled according to a standard mathematical classification scheme. Further, we investigate the appearance of new contents over time and their innovative combinations, which expand the knowledge network. In each network, we identify an innovation channel as a subgraph of triangles and larger simplices to which new tags attach. Our results show that the increasing topological complexity of the innovation channels contributes to networks architecture over different time periods, and is consistent with temporal correlations of the occurrence of new tags. The methodology applies to a wide class of data with the suitable temporal resolution and clearly identified knowledge-content units.
T2  - PLOS One
T1  - Topology of Innovation Spaces in the Knowledge Networks Emerging through Questions-And-Answers
VL  - 11
IS  - 5
DO  - 10.1371/journal.pone.0154655
ER  - 
@article{
author = "Anđelković, Miroslav and Tadić, Bosiljka and Mitrović Dankulov, Marija and Rajković, Milan and Melnik, Roderick",
year = "2016",
abstract = "The communication processes of knowledge creation represent a particular class of human dynamics where the expertise of individuals plays a substantial role, thus offering a unique possibility to study the structure of knowledge networks from online data. Here, we use the empirical evidence from questions-and-answers in mathematics to analyse the emergence of the network of knowledge contents (or tags) as the individual experts use them in the process. After removing extra edges from the network-associated graph, we apply the methods of algebraic topology of graphs to examine the structure of higher-order combinatorial spaces in networks for four consecutive time intervals. We find that the ranking distributions of the suitably scaled topological dimensions of nodes fall into a unique curve for all time intervals and filtering levels, suggesting a robust architecture of knowledge networks. Moreover, these networks preserve the logical structure of knowledge within emergent communities of nodes, labeled according to a standard mathematical classification scheme. Further, we investigate the appearance of new contents over time and their innovative combinations, which expand the knowledge network. In each network, we identify an innovation channel as a subgraph of triangles and larger simplices to which new tags attach. Our results show that the increasing topological complexity of the innovation channels contributes to networks architecture over different time periods, and is consistent with temporal correlations of the occurrence of new tags. The methodology applies to a wide class of data with the suitable temporal resolution and clearly identified knowledge-content units.",
journal = "PLOS One",
title = "Topology of Innovation Spaces in the Knowledge Networks Emerging through Questions-And-Answers",
volume = "11",
number = "5",
doi = "10.1371/journal.pone.0154655"
}
Anđelković, M., Tadić, B., Mitrović Dankulov, M., Rajković, M.,& Melnik, R.. (2016). Topology of Innovation Spaces in the Knowledge Networks Emerging through Questions-And-Answers. in PLOS One, 11(5).
https://doi.org/10.1371/journal.pone.0154655
Anđelković M, Tadić B, Mitrović Dankulov M, Rajković M, Melnik R. Topology of Innovation Spaces in the Knowledge Networks Emerging through Questions-And-Answers. in PLOS One. 2016;11(5).
doi:10.1371/journal.pone.0154655 .
Anđelković, Miroslav, Tadić, Bosiljka, Mitrović Dankulov, Marija, Rajković, Milan, Melnik, Roderick, "Topology of Innovation Spaces in the Knowledge Networks Emerging through Questions-And-Answers" in PLOS One, 11, no. 5 (2016),
https://doi.org/10.1371/journal.pone.0154655 . .
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Persistent topological features of dynamical systems

Maletić, Slobodan; Zhao, Yi; Rajković, Milan

(2016)

TY  - JOUR
AU  - Maletić, Slobodan
AU  - Zhao, Yi
AU  - Rajković, Milan
PY  - 2016
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/1115
AB  - Inspired by an early work of Muldoon et al., Physica D 65, 1-16 (1993), we present a general method for constructing simplicial complex from observed time series of dynamical systems based on the delay coordinate reconstruction procedure. The obtained simplicial complex preserves all pertinent topological features of the reconstructed phase space, and it may be analyzed from topological, combinatorial, and algebraic aspects. In focus of this study is the computation of homology of the invariant set of some well known dynamical systems that display chaotic behavior. Persistent homology of simplicial complex and its relationship with the embedding dimensions are examined by studying the lifetime of topological features and topological noise. The consistency of topological properties for different dynamic regimes and embedding dimensions is examined. The obtained results shed new light on the topological properties of the reconstructed phase space and open up new possibilities for application of advanced topological methods. The method presented here may be used as a generic method for constructing simplicial complex from a scalar time series that has a number of advantages compared to the mapping of the same time series to a complex network. Published by AIP Publishing.
T2  - Chaos
T1  - Persistent topological features of dynamical systems
VL  - 26
IS  - 5
DO  - 10.1063/1.4949472
ER  - 
@article{
author = "Maletić, Slobodan and Zhao, Yi and Rajković, Milan",
year = "2016",
abstract = "Inspired by an early work of Muldoon et al., Physica D 65, 1-16 (1993), we present a general method for constructing simplicial complex from observed time series of dynamical systems based on the delay coordinate reconstruction procedure. The obtained simplicial complex preserves all pertinent topological features of the reconstructed phase space, and it may be analyzed from topological, combinatorial, and algebraic aspects. In focus of this study is the computation of homology of the invariant set of some well known dynamical systems that display chaotic behavior. Persistent homology of simplicial complex and its relationship with the embedding dimensions are examined by studying the lifetime of topological features and topological noise. The consistency of topological properties for different dynamic regimes and embedding dimensions is examined. The obtained results shed new light on the topological properties of the reconstructed phase space and open up new possibilities for application of advanced topological methods. The method presented here may be used as a generic method for constructing simplicial complex from a scalar time series that has a number of advantages compared to the mapping of the same time series to a complex network. Published by AIP Publishing.",
journal = "Chaos",
title = "Persistent topological features of dynamical systems",
volume = "26",
number = "5",
doi = "10.1063/1.4949472"
}
Maletić, S., Zhao, Y.,& Rajković, M.. (2016). Persistent topological features of dynamical systems. in Chaos, 26(5).
https://doi.org/10.1063/1.4949472
Maletić S, Zhao Y, Rajković M. Persistent topological features of dynamical systems. in Chaos. 2016;26(5).
doi:10.1063/1.4949472 .
Maletić, Slobodan, Zhao, Yi, Rajković, Milan, "Persistent topological features of dynamical systems" in Chaos, 26, no. 5 (2016),
https://doi.org/10.1063/1.4949472 . .
1
40
31
39

Numerical Prediction of Nucleate Pool Boiling Heat Transfer Coefficient under High Heat Fluxes

Pezo, Milada L.; Stevanović, Vladimir D.

(2016)

TY  - JOUR
AU  - Pezo, Milada L.
AU  - Stevanović, Vladimir D.
PY  - 2016
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/1138
AB  - This paper presents computational fluid dynamics approach to prediction of the heat transfer coefficient for nucleate pool boiling under high heat fluxes. The 3-D numerical simulations of the atmospheric saturated pool boiling are performed. Mathematical modelling of pool boiling requires a treatment of vapor-liquid two-phase mixture on the macro level, as well as on the micro level, such as bubble growth and departure from the heating surface. Two-phase flow is modelled by the two-fluid model, which consists of the mass, momentum, and energy conservation equations for each phase. Interface transfer processes are calculated by the closure laws. Micro level phenomena on the heating surface are modelled with the bubble nucleation site density, the bubble resistance time on the heating wall and with the certain level of randomness in the location of bubble nucleation sites. The developed model was used to determine the heat transfer coefficient and results of numerical simulations are compared with available experimental results and several empirical correlations. A considerable scattering of the predictions of the pool boiling heat transfer coefficient by experimental correlations is observed, while the numerically predicted values are within the range of results calculated by well-known Kutateladze, Mostinski, Kruzhilin, and Rohsenow correlations. The presented numerical modelling approach is original regarding both the application of the two-fluid two-phase model for the determination of heat transfer coefficient in pool boiling and the defined boundary conditions at the heated wall surface.
T2  - Thermal Science
T1  - Numerical Prediction of Nucleate Pool Boiling Heat Transfer Coefficient under High Heat Fluxes
VL  - 20
SP  - S113
EP  - S123
DO  - 10.2298/TSCI150701138P
ER  - 
@article{
author = "Pezo, Milada L. and Stevanović, Vladimir D.",
year = "2016",
abstract = "This paper presents computational fluid dynamics approach to prediction of the heat transfer coefficient for nucleate pool boiling under high heat fluxes. The 3-D numerical simulations of the atmospheric saturated pool boiling are performed. Mathematical modelling of pool boiling requires a treatment of vapor-liquid two-phase mixture on the macro level, as well as on the micro level, such as bubble growth and departure from the heating surface. Two-phase flow is modelled by the two-fluid model, which consists of the mass, momentum, and energy conservation equations for each phase. Interface transfer processes are calculated by the closure laws. Micro level phenomena on the heating surface are modelled with the bubble nucleation site density, the bubble resistance time on the heating wall and with the certain level of randomness in the location of bubble nucleation sites. The developed model was used to determine the heat transfer coefficient and results of numerical simulations are compared with available experimental results and several empirical correlations. A considerable scattering of the predictions of the pool boiling heat transfer coefficient by experimental correlations is observed, while the numerically predicted values are within the range of results calculated by well-known Kutateladze, Mostinski, Kruzhilin, and Rohsenow correlations. The presented numerical modelling approach is original regarding both the application of the two-fluid two-phase model for the determination of heat transfer coefficient in pool boiling and the defined boundary conditions at the heated wall surface.",
journal = "Thermal Science",
title = "Numerical Prediction of Nucleate Pool Boiling Heat Transfer Coefficient under High Heat Fluxes",
volume = "20",
pages = "S113-S123",
doi = "10.2298/TSCI150701138P"
}
Pezo, M. L.,& Stevanović, V. D.. (2016). Numerical Prediction of Nucleate Pool Boiling Heat Transfer Coefficient under High Heat Fluxes. in Thermal Science, 20, S113-S123.
https://doi.org/10.2298/TSCI150701138P
Pezo ML, Stevanović VD. Numerical Prediction of Nucleate Pool Boiling Heat Transfer Coefficient under High Heat Fluxes. in Thermal Science. 2016;20:S113-S123.
doi:10.2298/TSCI150701138P .
Pezo, Milada L., Stevanović, Vladimir D., "Numerical Prediction of Nucleate Pool Boiling Heat Transfer Coefficient under High Heat Fluxes" in Thermal Science, 20 (2016):S113-S123,
https://doi.org/10.2298/TSCI150701138P . .
9
10
10

Numerical Investigation of Nucleate Pool Boiling Heat Transfer

Stojanović, Andrijana D.; Stevanović, Vladimir D.; Petrović, Milan M.; Zivkovic, Dragoljub S.

(2016)

TY  - JOUR
AU  - Stojanović, Andrijana D.
AU  - Stevanović, Vladimir D.
AU  - Petrović, Milan M.
AU  - Zivkovic, Dragoljub S.
PY  - 2016
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/7136
AB  - Multi-dimensional numerical simulation of the atmospheric saturated pool boiling is performed. The applied modelling and numerical methods enable a full representation of the liquid and vapour two-phase mixture behaviour on the heated surface, with included prediction of the swell level and heated wall temperature field. In this way the integral behaviour of nucleate pool boiling is simulated. The micro conditions of bubble generation at the heated wall surface are modelled by the bubble nucleation site density, the liquid wetting contact angle and the bubble grow time. The bubble nucleation sites are randomly located within zones of equal size, where the number of zones equals the nucleation site density. The conjugate heat transfer from the heated wall to the liquid is taken into account in wetted heated wall areas around bubble nucleation sites. The boiling curve relation between the heat flux and the heated wall surface temperature in excess of the saturation temperature is predicted for the pool boiling conditions reported in the literature and a good agreement is achieved with experimentally measured data. The influence of the nucleation site density on the boiling curve characteristic is confirmed. In addition, the influence of the heat flux intensity on the spatial effects of vapour generation and two-phase flow are shown, such as the increase of the swell level position and the reduced wetting of the heated wall surface by the heat flux increase.
T2  - Thermal Science
T1  - Numerical Investigation of Nucleate Pool Boiling Heat Transfer
VL  - 20
SP  - S1301
EP  - S1312
DO  - 10.2298/TSCI160404276S
ER  - 
@article{
author = "Stojanović, Andrijana D. and Stevanović, Vladimir D. and Petrović, Milan M. and Zivkovic, Dragoljub S.",
year = "2016",
abstract = "Multi-dimensional numerical simulation of the atmospheric saturated pool boiling is performed. The applied modelling and numerical methods enable a full representation of the liquid and vapour two-phase mixture behaviour on the heated surface, with included prediction of the swell level and heated wall temperature field. In this way the integral behaviour of nucleate pool boiling is simulated. The micro conditions of bubble generation at the heated wall surface are modelled by the bubble nucleation site density, the liquid wetting contact angle and the bubble grow time. The bubble nucleation sites are randomly located within zones of equal size, where the number of zones equals the nucleation site density. The conjugate heat transfer from the heated wall to the liquid is taken into account in wetted heated wall areas around bubble nucleation sites. The boiling curve relation between the heat flux and the heated wall surface temperature in excess of the saturation temperature is predicted for the pool boiling conditions reported in the literature and a good agreement is achieved with experimentally measured data. The influence of the nucleation site density on the boiling curve characteristic is confirmed. In addition, the influence of the heat flux intensity on the spatial effects of vapour generation and two-phase flow are shown, such as the increase of the swell level position and the reduced wetting of the heated wall surface by the heat flux increase.",
journal = "Thermal Science",
title = "Numerical Investigation of Nucleate Pool Boiling Heat Transfer",
volume = "20",
pages = "S1301-S1312",
doi = "10.2298/TSCI160404276S"
}
Stojanović, A. D., Stevanović, V. D., Petrović, M. M.,& Zivkovic, D. S.. (2016). Numerical Investigation of Nucleate Pool Boiling Heat Transfer. in Thermal Science, 20, S1301-S1312.
https://doi.org/10.2298/TSCI160404276S
Stojanović AD, Stevanović VD, Petrović MM, Zivkovic DS. Numerical Investigation of Nucleate Pool Boiling Heat Transfer. in Thermal Science. 2016;20:S1301-S1312.
doi:10.2298/TSCI160404276S .
Stojanović, Andrijana D., Stevanović, Vladimir D., Petrović, Milan M., Zivkovic, Dragoljub S., "Numerical Investigation of Nucleate Pool Boiling Heat Transfer" in Thermal Science, 20 (2016):S1301-S1312,
https://doi.org/10.2298/TSCI160404276S . .
4
3
3

Hierarchical sequencing of online social graphs

Anđelković, Miroslav; Tadić, Bosiljka; Maletić, Slobodan; Rajković, Milan

(2015)

TY  - JOUR
AU  - Anđelković, Miroslav
AU  - Tadić, Bosiljka
AU  - Maletić, Slobodan
AU  - Rajković, Milan
PY  - 2015
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/648
AB  - In online communications, patterns of conduct of individual actors and use of emotions in the process can lead to a complex social graph exhibiting multilayered structure and meso-scopic communities. Using simplicial complexes representation of graphs, we investigate in-depth topology of the online social network constructed from MySpace dialogs which exhibits original community structure. A simulation of emotion spreading in this network leads to the identification of two emotion-propagating layers. Three topological measures are introduced, referred to as the structure vectors, which quantify graphs architecture at different dimension levels. Notably, structures emerging through shared links, triangles and tetrahedral faces, frequently occur and range from tree-like to maximal 5-cliques and their respective complexes. On the other hand, the structures which spread only negative or only positive emotion messages appear to have much simpler topology consisting of links and triangles. The nodes structure vector represents the number of simplices at each topology level in which the node resides and the total number of such simplices determines what we define as the nodes topological dimension. The presented results suggest that the nodes topological dimension provides a suitable measure of the social capital which measures the actors ability to act as a broker in compact communities, the so called Simmelian brokerage. We also generalize the results to a wider class of computer-generated networks. Investigating components of the nodes vector over network layers reveals that same nodes develop different socio-emotional relations and that the influential nodes build social capital by combining their connections in different layers. (C) 2015 Elsevier B.V. All rights reserved.
T2  - Physica A: Statistical Mechanics and Its Applications
T1  - Hierarchical sequencing of online social graphs
VL  - 436
SP  - 582
EP  - 595
DO  - 10.1016/j.physa.2015.05.075
ER  - 
@article{
author = "Anđelković, Miroslav and Tadić, Bosiljka and Maletić, Slobodan and Rajković, Milan",
year = "2015",
abstract = "In online communications, patterns of conduct of individual actors and use of emotions in the process can lead to a complex social graph exhibiting multilayered structure and meso-scopic communities. Using simplicial complexes representation of graphs, we investigate in-depth topology of the online social network constructed from MySpace dialogs which exhibits original community structure. A simulation of emotion spreading in this network leads to the identification of two emotion-propagating layers. Three topological measures are introduced, referred to as the structure vectors, which quantify graphs architecture at different dimension levels. Notably, structures emerging through shared links, triangles and tetrahedral faces, frequently occur and range from tree-like to maximal 5-cliques and their respective complexes. On the other hand, the structures which spread only negative or only positive emotion messages appear to have much simpler topology consisting of links and triangles. The nodes structure vector represents the number of simplices at each topology level in which the node resides and the total number of such simplices determines what we define as the nodes topological dimension. The presented results suggest that the nodes topological dimension provides a suitable measure of the social capital which measures the actors ability to act as a broker in compact communities, the so called Simmelian brokerage. We also generalize the results to a wider class of computer-generated networks. Investigating components of the nodes vector over network layers reveals that same nodes develop different socio-emotional relations and that the influential nodes build social capital by combining their connections in different layers. (C) 2015 Elsevier B.V. All rights reserved.",
journal = "Physica A: Statistical Mechanics and Its Applications",
title = "Hierarchical sequencing of online social graphs",
volume = "436",
pages = "582-595",
doi = "10.1016/j.physa.2015.05.075"
}
Anđelković, M., Tadić, B., Maletić, S.,& Rajković, M.. (2015). Hierarchical sequencing of online social graphs. in Physica A: Statistical Mechanics and Its Applications, 436, 582-595.
https://doi.org/10.1016/j.physa.2015.05.075
Anđelković M, Tadić B, Maletić S, Rajković M. Hierarchical sequencing of online social graphs. in Physica A: Statistical Mechanics and Its Applications. 2015;436:582-595.
doi:10.1016/j.physa.2015.05.075 .
Anđelković, Miroslav, Tadić, Bosiljka, Maletić, Slobodan, Rajković, Milan, "Hierarchical sequencing of online social graphs" in Physica A: Statistical Mechanics and Its Applications, 436 (2015):582-595,
https://doi.org/10.1016/j.physa.2015.05.075 . .
1
24
23
22

Lattice Monte Carlo simulation of single coal char particle combustion under oxy-fuel conditions

Jovanović, Rastko D.; Marek, Ewa; Maletić, Slobodan; Cvetinović, Dejan; Marković, Zoran J.

(2015)

TY  - JOUR
AU  - Jovanović, Rastko D.
AU  - Marek, Ewa
AU  - Maletić, Slobodan
AU  - Cvetinović, Dejan
AU  - Marković, Zoran J.
PY  - 2015
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/7066
AB  - A descriptive model for isolated char particle combustion under conventional and oxy-fuel conditions was developed. Suggested model is based on the percolation theory and Monte Carlo simulation technique. Char particle was modeled as a square lattice consisting of a large number of small sites. Sites correspond either to fixed carbon, ash, or pore, and they were distributed randomly inside char lattice using percolation concept, at the start of simulation. Random walk model was used to represent gaseous species diffusion through particle pores. Char combustion was modeled using power law Arrhenius model which assumes that reaction rate depends of particle temperature and oxygen partial pressure on particle surface. The main aim of the proposed model was to take into account influence of heterogeneous char particle structure to randomness of the char combustion process. The suggested models behavior was validated by qualitative comparison with experimental data obtained in single particle reactor. It was found that simulated combustion time, char burnout and particle temperature values are in good agreement with experimentally determined data. Special emphasis was given to the CO2 gasification reaction influence on char conversion and particle temperature values. Further development of the proposed model with appropriate simplifications would enable its inclusion in comprehensive CFD codes. (C) 2015 Elsevier Ltd. All rights reserved.
T2  - Fuel
T1  - Lattice Monte Carlo simulation of single coal char particle combustion under oxy-fuel conditions
VL  - 151
SP  - 172
EP  - 181
DO  - 10.1016/j.fuel.2015.02.104
ER  - 
@article{
author = "Jovanović, Rastko D. and Marek, Ewa and Maletić, Slobodan and Cvetinović, Dejan and Marković, Zoran J.",
year = "2015",
abstract = "A descriptive model for isolated char particle combustion under conventional and oxy-fuel conditions was developed. Suggested model is based on the percolation theory and Monte Carlo simulation technique. Char particle was modeled as a square lattice consisting of a large number of small sites. Sites correspond either to fixed carbon, ash, or pore, and they were distributed randomly inside char lattice using percolation concept, at the start of simulation. Random walk model was used to represent gaseous species diffusion through particle pores. Char combustion was modeled using power law Arrhenius model which assumes that reaction rate depends of particle temperature and oxygen partial pressure on particle surface. The main aim of the proposed model was to take into account influence of heterogeneous char particle structure to randomness of the char combustion process. The suggested models behavior was validated by qualitative comparison with experimental data obtained in single particle reactor. It was found that simulated combustion time, char burnout and particle temperature values are in good agreement with experimentally determined data. Special emphasis was given to the CO2 gasification reaction influence on char conversion and particle temperature values. Further development of the proposed model with appropriate simplifications would enable its inclusion in comprehensive CFD codes. (C) 2015 Elsevier Ltd. All rights reserved.",
journal = "Fuel",
title = "Lattice Monte Carlo simulation of single coal char particle combustion under oxy-fuel conditions",
volume = "151",
pages = "172-181",
doi = "10.1016/j.fuel.2015.02.104"
}
Jovanović, R. D., Marek, E., Maletić, S., Cvetinović, D.,& Marković, Z. J.. (2015). Lattice Monte Carlo simulation of single coal char particle combustion under oxy-fuel conditions. in Fuel, 151, 172-181.
https://doi.org/10.1016/j.fuel.2015.02.104
Jovanović RD, Marek E, Maletić S, Cvetinović D, Marković ZJ. Lattice Monte Carlo simulation of single coal char particle combustion under oxy-fuel conditions. in Fuel. 2015;151:172-181.
doi:10.1016/j.fuel.2015.02.104 .
Jovanović, Rastko D., Marek, Ewa, Maletić, Slobodan, Cvetinović, Dejan, Marković, Zoran J., "Lattice Monte Carlo simulation of single coal char particle combustion under oxy-fuel conditions" in Fuel, 151 (2015):172-181,
https://doi.org/10.1016/j.fuel.2015.02.104 . .
16
17
18

Hidden geometry of traffic jamming

Anđelković, Miroslav; Gupte, Neelima; Tadić, Bosiljka

(2015)

TY  - JOUR
AU  - Anđelković, Miroslav
AU  - Gupte, Neelima
AU  - Tadić, Bosiljka
PY  - 2015
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/563
AB  - We introduce an approach based on algebraic topological methods that allow an accurate characterization of jamming in dynamical systems with queues. As a prototype system, we analyze the traffic of information packets with navigation and queuing at nodes on a network substrate in distinct dynamical regimes. A temporal sequence of traffic density fluctuations is mapped onto a mathematical graph in which each vertex denotes one dynamical state of the system. The coupling complexity between these states is revealed by classifying agglomerates of high-dimensional cliques that are intermingled at different topological levels and quantified by a set of geometrical and entropy measures. The free-flow, jamming, and congested traffic regimes result in graphs of different structure, while the largest geometrical complexity and minimum entropy mark the edge of the jamming region.
T2  - Physical Review E
T1  - Hidden geometry of traffic jamming
VL  - 91
IS  - 5
DO  - 10.1103/PhysRevE.91.052817
ER  - 
@article{
author = "Anđelković, Miroslav and Gupte, Neelima and Tadić, Bosiljka",
year = "2015",
abstract = "We introduce an approach based on algebraic topological methods that allow an accurate characterization of jamming in dynamical systems with queues. As a prototype system, we analyze the traffic of information packets with navigation and queuing at nodes on a network substrate in distinct dynamical regimes. A temporal sequence of traffic density fluctuations is mapped onto a mathematical graph in which each vertex denotes one dynamical state of the system. The coupling complexity between these states is revealed by classifying agglomerates of high-dimensional cliques that are intermingled at different topological levels and quantified by a set of geometrical and entropy measures. The free-flow, jamming, and congested traffic regimes result in graphs of different structure, while the largest geometrical complexity and minimum entropy mark the edge of the jamming region.",
journal = "Physical Review E",
title = "Hidden geometry of traffic jamming",
volume = "91",
number = "5",
doi = "10.1103/PhysRevE.91.052817"
}
Anđelković, M., Gupte, N.,& Tadić, B.. (2015). Hidden geometry of traffic jamming. in Physical Review E, 91(5).
https://doi.org/10.1103/PhysRevE.91.052817
Anđelković M, Gupte N, Tadić B. Hidden geometry of traffic jamming. in Physical Review E. 2015;91(5).
doi:10.1103/PhysRevE.91.052817 .
Anđelković, Miroslav, Gupte, Neelima, Tadić, Bosiljka, "Hidden geometry of traffic jamming" in Physical Review E, 91, no. 5 (2015),
https://doi.org/10.1103/PhysRevE.91.052817 . .
2
27
26
27

Consensus formation on a simplicial complex of opinions

Maletić, Slobodan; Rajković, Milan

(2014)

TY  - JOUR
AU  - Maletić, Slobodan
AU  - Rajković, Milan
PY  - 2014
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/5883
AB  - Geometric realization of an opinion is considered as a simplex and the opinion space of a group of individuals is a simplicial complex whose topological features are monitored in the process of opinion formation. The agents are physically located at the nodes of a scale-free and a random network. Social interactions include all concepts of social dynamics present in the mainstream models, augmented by four additional interaction mechanisms which depend on the local properties of opinions and their overlapping properties. The results pertaining to the formation of consensus are of particular interest. An analogy with quantum mechanical pure states is established through the application of the high-dimensional combinatorial Laplacian. (C) 2013 Elsevier B.V. All rights reserved.
T2  - Physica A: Statistical Mechanics and Its Applications
T1  - Consensus formation on a simplicial complex of opinions
VL  - 397
SP  - 111
EP  - 120
DO  - 10.1016/j.physa.2013.12.001
ER  - 
@article{
author = "Maletić, Slobodan and Rajković, Milan",
year = "2014",
abstract = "Geometric realization of an opinion is considered as a simplex and the opinion space of a group of individuals is a simplicial complex whose topological features are monitored in the process of opinion formation. The agents are physically located at the nodes of a scale-free and a random network. Social interactions include all concepts of social dynamics present in the mainstream models, augmented by four additional interaction mechanisms which depend on the local properties of opinions and their overlapping properties. The results pertaining to the formation of consensus are of particular interest. An analogy with quantum mechanical pure states is established through the application of the high-dimensional combinatorial Laplacian. (C) 2013 Elsevier B.V. All rights reserved.",
journal = "Physica A: Statistical Mechanics and Its Applications",
title = "Consensus formation on a simplicial complex of opinions",
volume = "397",
pages = "111-120",
doi = "10.1016/j.physa.2013.12.001"
}
Maletić, S.,& Rajković, M.. (2014). Consensus formation on a simplicial complex of opinions. in Physica A: Statistical Mechanics and Its Applications, 397, 111-120.
https://doi.org/10.1016/j.physa.2013.12.001
Maletić S, Rajković M. Consensus formation on a simplicial complex of opinions. in Physica A: Statistical Mechanics and Its Applications. 2014;397:111-120.
doi:10.1016/j.physa.2013.12.001 .
Maletić, Slobodan, Rajković, Milan, "Consensus formation on a simplicial complex of opinions" in Physica A: Statistical Mechanics and Its Applications, 397 (2014):111-120,
https://doi.org/10.1016/j.physa.2013.12.001 . .
1
19
19
19

Quantifying self-organization with optimal wavelets

Milovanović, Miloš; Rajković, Milan

(2013)

TY  - JOUR
AU  - Milovanović, Miloš
AU  - Rajković, Milan
PY  - 2013
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/5569
AB  - An optimal wavelet basis is used to develop a quantitative, experimentally applicable criterion for self-organization. The choice of the optimal wavelet is based on the model of selforganization in the wavelet tree. The framework of the model is founded on the wavelet-domain hidden Markov model and the optimal wavelet basis criterion for self-organization. The principle assumes increase in statistical complexity considered as the information content necessary for maximally accurate prediction of the systems dynamics. The causal states and the wavelet machine (w-machine) are defined in analogy with the epsilon-machine constructed as the unique, minimal, predictive model of the process. The method, presented here for the one-dimensional data, concurrently performs superior denoising and may be easily generalized to higher dimensions. Copyright (C) EPLA, 2013
T2  - Europhysics Letters / EPL
T1  - Quantifying self-organization with optimal wavelets
VL  - 102
IS  - 4
DO  - 10.1209/0295-5075/102/40004
ER  - 
@article{
author = "Milovanović, Miloš and Rajković, Milan",
year = "2013",
abstract = "An optimal wavelet basis is used to develop a quantitative, experimentally applicable criterion for self-organization. The choice of the optimal wavelet is based on the model of selforganization in the wavelet tree. The framework of the model is founded on the wavelet-domain hidden Markov model and the optimal wavelet basis criterion for self-organization. The principle assumes increase in statistical complexity considered as the information content necessary for maximally accurate prediction of the systems dynamics. The causal states and the wavelet machine (w-machine) are defined in analogy with the epsilon-machine constructed as the unique, minimal, predictive model of the process. The method, presented here for the one-dimensional data, concurrently performs superior denoising and may be easily generalized to higher dimensions. Copyright (C) EPLA, 2013",
journal = "Europhysics Letters / EPL",
title = "Quantifying self-organization with optimal wavelets",
volume = "102",
number = "4",
doi = "10.1209/0295-5075/102/40004"
}
Milovanović, M.,& Rajković, M.. (2013). Quantifying self-organization with optimal wavelets. in Europhysics Letters / EPL, 102(4).
https://doi.org/10.1209/0295-5075/102/40004
Milovanović M, Rajković M. Quantifying self-organization with optimal wavelets. in Europhysics Letters / EPL. 2013;102(4).
doi:10.1209/0295-5075/102/40004 .
Milovanović, Miloš, Rajković, Milan, "Quantifying self-organization with optimal wavelets" in Europhysics Letters / EPL, 102, no. 4 (2013),
https://doi.org/10.1209/0295-5075/102/40004 . .
1
4
4
5

Cooperation, Conflict and Higher-Order Structures of Social Networks

Maletić, Slobodan; Horak, Danijela; Rajković, Milan

(2012)

TY  - JOUR
AU  - Maletić, Slobodan
AU  - Horak, Danijela
AU  - Rajković, Milan
PY  - 2012
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/4886
AB  - Simplicial complexes represent powerful models of complex networks and complex systems in general. We explore the properties of spectra of combinatorial Laplacian operator of simplicial complexes in the context of connectivity of cliques in the simplicial clique complex associated with social networks. The necessity of higher order spectral analysis is discussed and compared with results for ordinary graph spectra. Methods and results are applied using social network of the Zachary karate club and the network of characters from Victor Hugos novel Les Miserables.
T2  - Advances in Complex Systems
T1  - Cooperation, Conflict and Higher-Order Structures of Social Networks
VL  - 15
DO  - 10.1142/S0219525912500555
ER  - 
@article{
author = "Maletić, Slobodan and Horak, Danijela and Rajković, Milan",
year = "2012",
abstract = "Simplicial complexes represent powerful models of complex networks and complex systems in general. We explore the properties of spectra of combinatorial Laplacian operator of simplicial complexes in the context of connectivity of cliques in the simplicial clique complex associated with social networks. The necessity of higher order spectral analysis is discussed and compared with results for ordinary graph spectra. Methods and results are applied using social network of the Zachary karate club and the network of characters from Victor Hugos novel Les Miserables.",
journal = "Advances in Complex Systems",
title = "Cooperation, Conflict and Higher-Order Structures of Social Networks",
volume = "15",
doi = "10.1142/S0219525912500555"
}
Maletić, S., Horak, D.,& Rajković, M.. (2012). Cooperation, Conflict and Higher-Order Structures of Social Networks. in Advances in Complex Systems, 15.
https://doi.org/10.1142/S0219525912500555
Maletić S, Horak D, Rajković M. Cooperation, Conflict and Higher-Order Structures of Social Networks. in Advances in Complex Systems. 2012;15.
doi:10.1142/S0219525912500555 .
Maletić, Slobodan, Horak, Danijela, Rajković, Milan, "Cooperation, Conflict and Higher-Order Structures of Social Networks" in Advances in Complex Systems, 15 (2012),
https://doi.org/10.1142/S0219525912500555 . .
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Performance optimization of the BIPV powered electrolyser and fuel cells installation

Stamenić, Ljubisav; Rajković, Milan; Klisic, Dorde

(2012)

TY  - JOUR
AU  - Stamenić, Ljubisav
AU  - Rajković, Milan
AU  - Klisic, Dorde
PY  - 2012
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/5019
AB  - A practical multipurpose implementation of hybrid renewable energy system completely located within the building and including building integrated photovoltaic (BIPV) solar power energy source is presented. The system uses solar photovoltaic electricity generated by the building skin to produce hydrogen for fuel-cells, which in turn, when converted to energy in fuel cells, may be used to supply additional power to the building (or fuel cell vehicles) when solar power is not sufficient, for example at night or in periods of low insolation. Electricity generated from 8.2 kW(p) BIPV array optimally supplies the electrolyser near the maximum power point level of the BIPV array. To further optimize hydrogen production, the electrolyser is connected to the local electrical utility, and DC power is provided to the electrolyser through a custom on-board DC power supply that supplements the BIPV array. Performance of the complete installation is optimized to provide continual production at the optimal efficiency level of hydrogen production at constant power. The results obtained from the system operation have shown excellent voltage and current regulation during operation of the electrolyser. The project shows the potential for development of similar building integrated hybrid systems elsewhere with possibilities for inclusion of additional renewable energy sources and added functionality. (C) 2012 Elsevier B.V. All rights reserved.
T2  - Energy and Buildings
T1  - Performance optimization of the BIPV powered electrolyser and fuel cells installation
VL  - 51
SP  - 39
EP  - 47
DO  - 10.1016/j.enbuild.2012.03.044
ER  - 
@article{
author = "Stamenić, Ljubisav and Rajković, Milan and Klisic, Dorde",
year = "2012",
abstract = "A practical multipurpose implementation of hybrid renewable energy system completely located within the building and including building integrated photovoltaic (BIPV) solar power energy source is presented. The system uses solar photovoltaic electricity generated by the building skin to produce hydrogen for fuel-cells, which in turn, when converted to energy in fuel cells, may be used to supply additional power to the building (or fuel cell vehicles) when solar power is not sufficient, for example at night or in periods of low insolation. Electricity generated from 8.2 kW(p) BIPV array optimally supplies the electrolyser near the maximum power point level of the BIPV array. To further optimize hydrogen production, the electrolyser is connected to the local electrical utility, and DC power is provided to the electrolyser through a custom on-board DC power supply that supplements the BIPV array. Performance of the complete installation is optimized to provide continual production at the optimal efficiency level of hydrogen production at constant power. The results obtained from the system operation have shown excellent voltage and current regulation during operation of the electrolyser. The project shows the potential for development of similar building integrated hybrid systems elsewhere with possibilities for inclusion of additional renewable energy sources and added functionality. (C) 2012 Elsevier B.V. All rights reserved.",
journal = "Energy and Buildings",
title = "Performance optimization of the BIPV powered electrolyser and fuel cells installation",
volume = "51",
pages = "39-47",
doi = "10.1016/j.enbuild.2012.03.044"
}
Stamenić, L., Rajković, M.,& Klisic, D.. (2012). Performance optimization of the BIPV powered electrolyser and fuel cells installation. in Energy and Buildings, 51, 39-47.
https://doi.org/10.1016/j.enbuild.2012.03.044
Stamenić L, Rajković M, Klisic D. Performance optimization of the BIPV powered electrolyser and fuel cells installation. in Energy and Buildings. 2012;51:39-47.
doi:10.1016/j.enbuild.2012.03.044 .
Stamenić, Ljubisav, Rajković, Milan, Klisic, Dorde, "Performance optimization of the BIPV powered electrolyser and fuel cells installation" in Energy and Buildings, 51 (2012):39-47,
https://doi.org/10.1016/j.enbuild.2012.03.044 . .
8
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Combinatorial Laplacian and entropy of simplicial complexes associated with complex networks

Maletić, Slobodan; Rajković, Milan

(2012)

TY  - JOUR
AU  - Maletić, Slobodan
AU  - Rajković, Milan
PY  - 2012
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/5035
AB  - Simplicial complexes represent useful and accurate models of complex networks and complex systems in general. We explore the properties of spectra of combinatorial Laplacian operator of simplicial complexes and show its relationship with connectivity properties of the Q-vector and with connectivities of cliques in the simplicial clique complex. We demonstrate the need for higher order analysis in complex networks and compare the results with ordinary graph spectra. Methods and results are obtained using social network of the Zachary karate club.
T2  - European Physical Journal - Special Topics
T1  - Combinatorial Laplacian and entropy of simplicial complexes associated with complex networks
VL  - 212
IS  - 1
SP  - 77
EP  - 97
DO  - 10.1140/epjst/e2012-01655-6
ER  - 
@article{
author = "Maletić, Slobodan and Rajković, Milan",
year = "2012",
abstract = "Simplicial complexes represent useful and accurate models of complex networks and complex systems in general. We explore the properties of spectra of combinatorial Laplacian operator of simplicial complexes and show its relationship with connectivity properties of the Q-vector and with connectivities of cliques in the simplicial clique complex. We demonstrate the need for higher order analysis in complex networks and compare the results with ordinary graph spectra. Methods and results are obtained using social network of the Zachary karate club.",
journal = "European Physical Journal - Special Topics",
title = "Combinatorial Laplacian and entropy of simplicial complexes associated with complex networks",
volume = "212",
number = "1",
pages = "77-97",
doi = "10.1140/epjst/e2012-01655-6"
}
Maletić, S.,& Rajković, M.. (2012). Combinatorial Laplacian and entropy of simplicial complexes associated with complex networks. in European Physical Journal - Special Topics, 212(1), 77-97.
https://doi.org/10.1140/epjst/e2012-01655-6
Maletić S, Rajković M. Combinatorial Laplacian and entropy of simplicial complexes associated with complex networks. in European Physical Journal - Special Topics. 2012;212(1):77-97.
doi:10.1140/epjst/e2012-01655-6 .
Maletić, Slobodan, Rajković, Milan, "Combinatorial Laplacian and entropy of simplicial complexes associated with complex networks" in European Physical Journal - Special Topics, 212, no. 1 (2012):77-97,
https://doi.org/10.1140/epjst/e2012-01655-6 . .
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Characterization of Turbulence and Transport in Magnetic Confinement Devices

Rajković, Milan; Watanabe, T. -H.; Škorić, Miloš M.

(2012)

TY  - CONF
AU  - Rajković, Milan
AU  - Watanabe, T. -H.
AU  - Škorić, Miloš M.
PY  - 2012
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/6945
AB  - Intermittency in the scrape-off layer (SOL) region of magnetically confine plasma and velocity intermittency of neutral flui are compared from the aspect of global and local multifractal properties. Density fluctuation in the MAST device are considered and contrasted to local velocity measurements of an air fl w into round free jet. Large deviation (multifractal) spectra are used to characterize global features revealing different energy cascade mechanisms in each of systems. A transformation invariant zero-crossing function is shown to be more reliable indicator of stable equilibrium states then the probability density function. In particular the zero-crossing function detects L-H transitions and recognizes ELMs as catastropohic events in the sense of stochastic catastrophy theory. The method may be of significan importance in the analysis and control of edge plasma turbulence.
C3  - AIP Conference Proceedings
T1  - Characterization of Turbulence and Transport in Magnetic Confinement Devices
VL  - 1445
DO  - 10.1063/1.3701883
ER  - 
@conference{
author = "Rajković, Milan and Watanabe, T. -H. and Škorić, Miloš M.",
year = "2012",
abstract = "Intermittency in the scrape-off layer (SOL) region of magnetically confine plasma and velocity intermittency of neutral flui are compared from the aspect of global and local multifractal properties. Density fluctuation in the MAST device are considered and contrasted to local velocity measurements of an air fl w into round free jet. Large deviation (multifractal) spectra are used to characterize global features revealing different energy cascade mechanisms in each of systems. A transformation invariant zero-crossing function is shown to be more reliable indicator of stable equilibrium states then the probability density function. In particular the zero-crossing function detects L-H transitions and recognizes ELMs as catastropohic events in the sense of stochastic catastrophy theory. The method may be of significan importance in the analysis and control of edge plasma turbulence.",
journal = "AIP Conference Proceedings",
title = "Characterization of Turbulence and Transport in Magnetic Confinement Devices",
volume = "1445",
doi = "10.1063/1.3701883"
}
Rajković, M., Watanabe, T. -H.,& Škorić, M. M.. (2012). Characterization of Turbulence and Transport in Magnetic Confinement Devices. in AIP Conference Proceedings, 1445.
https://doi.org/10.1063/1.3701883
Rajković M, Watanabe T-, Škorić MM. Characterization of Turbulence and Transport in Magnetic Confinement Devices. in AIP Conference Proceedings. 2012;1445.
doi:10.1063/1.3701883 .
Rajković, Milan, Watanabe, T. -H., Škorić, Miloš M., "Characterization of Turbulence and Transport in Magnetic Confinement Devices" in AIP Conference Proceedings, 1445 (2012),
https://doi.org/10.1063/1.3701883 . .

Numerical prediction of critical heat flux in pool boiling with the two-fluid model

Pezo, Milada L.; Stevanović, Vladimir

(2011)

TY  - JOUR
AU  - Pezo, Milada L.
AU  - Stevanović, Vladimir
PY  - 2011
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/4395
AB  - Three-dimensional numerical simulations of the atmospheric saturated pool boiling are performed with the aim of predicting the critical heat flux. The two-phase mixture in pool boiling is described with the transient two-fluid model. The transient heat conduction in the horizontal heated wall is also solved. Dynamics of vapor generation on the heated wall is modeled through the density of nucleation sites and the bubble residence time on the wall. The heaters surface is divided into zones, which number per unit area equals the density of nucleation sites, while the location of nucleation site within each zone is determined by a random function. The results show a replenishment of the heaters surface with water and surface wetting for lower heat fluxes, while heaters surface dry-out is predicted at critical heat flux values. Also, it is shown that the decrease of nucleation site density leads to the reduction of critical heat flux values. Obtained results of critical heat flux are in good agreement with available measured data. The presented approach is original regarding both the application of the two-fluid two-phase model for the prediction of boiling crisis in pool boiling and the defined boundary conditions at the heated wall surface. (C) 2011 Elsevier Ltd. All rights reserved.
T2  - International Journal of Heat and Mass Transfer
T1  - Numerical prediction of critical heat flux in pool boiling with the two-fluid model
VL  - 54
IS  - 15-16
SP  - 3296
EP  - 3303
DO  - 10.1016/j.ijheatmasstransfer.2011.03.057
ER  - 
@article{
author = "Pezo, Milada L. and Stevanović, Vladimir",
year = "2011",
abstract = "Three-dimensional numerical simulations of the atmospheric saturated pool boiling are performed with the aim of predicting the critical heat flux. The two-phase mixture in pool boiling is described with the transient two-fluid model. The transient heat conduction in the horizontal heated wall is also solved. Dynamics of vapor generation on the heated wall is modeled through the density of nucleation sites and the bubble residence time on the wall. The heaters surface is divided into zones, which number per unit area equals the density of nucleation sites, while the location of nucleation site within each zone is determined by a random function. The results show a replenishment of the heaters surface with water and surface wetting for lower heat fluxes, while heaters surface dry-out is predicted at critical heat flux values. Also, it is shown that the decrease of nucleation site density leads to the reduction of critical heat flux values. Obtained results of critical heat flux are in good agreement with available measured data. The presented approach is original regarding both the application of the two-fluid two-phase model for the prediction of boiling crisis in pool boiling and the defined boundary conditions at the heated wall surface. (C) 2011 Elsevier Ltd. All rights reserved.",
journal = "International Journal of Heat and Mass Transfer",
title = "Numerical prediction of critical heat flux in pool boiling with the two-fluid model",
volume = "54",
number = "15-16",
pages = "3296-3303",
doi = "10.1016/j.ijheatmasstransfer.2011.03.057"
}
Pezo, M. L.,& Stevanović, V.. (2011). Numerical prediction of critical heat flux in pool boiling with the two-fluid model. in International Journal of Heat and Mass Transfer, 54(15-16), 3296-3303.
https://doi.org/10.1016/j.ijheatmasstransfer.2011.03.057
Pezo ML, Stevanović V. Numerical prediction of critical heat flux in pool boiling with the two-fluid model. in International Journal of Heat and Mass Transfer. 2011;54(15-16):3296-3303.
doi:10.1016/j.ijheatmasstransfer.2011.03.057 .
Pezo, Milada L., Stevanović, Vladimir, "Numerical prediction of critical heat flux in pool boiling with the two-fluid model" in International Journal of Heat and Mass Transfer, 54, no. 15-16 (2011):3296-3303,
https://doi.org/10.1016/j.ijheatmasstransfer.2011.03.057 . .
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