Vittorio Rosato | ENEA, Italian National Agency for New Technologies, Energy and Sustainable Economic Development (original) (raw)
Papers by Vittorio Rosato
Physica A: Statistical Mechanics and its Applications, 2008
The Internet is one of the most interesting realizations of a "complex" network. As a non-supervi... more The Internet is one of the most interesting realizations of a "complex" network. As a non-supervised growing object, it allows the study of the selective pressure which drives the network to assume its current structure. The DIMES and the ROUTEVIEWS projects are ongoing projects aimed at evaluating the topological structure of the Internet (at the Autonomous System or AS grainlevel) on the basis of different types of measurements. The topological analysis of the networks produced by the two projects has allowed us to infer a growth mechanism which has been used to build up synthetic networks with similar properties. These networks have been used as test-beds for the implementation of a model of traffic dynamics, with the aim of assessing the ability of the Internet's topology to support the basic actions for data traffic handling. Results have been compared with those obtained by using a random network of similar size. The effects of some structural perturbations (arcs and nodes' removal, traffic localization) have been also evaluated in terms of the induced variations of the network's efficiency. The resulting scenario is consistent with the hypothesis that the structure of the Internet is only partially fit to host communication processes and that the intelligence of the TCP/IP protocol is partly needed to overcome some "structural" deficiencies.
Understanding Complex Systems, 2008
A Complex System's View of Critical Infrastructures Vittorio Rosato1, Ingve Simonsen3'4... more A Complex System's View of Critical Infrastructures Vittorio Rosato1, Ingve Simonsen3'4, Sandro Meloni1, Limor Issacharoff1'3, Karsten Peters2, Nils von Festenberg3, Dirk Helbing5 1 ENEA, Casaccia Research Center, Computing and ...
Journal of Computational Physics, 2001
The user has requested enhancement of the downloaded file. All in-text references underlined in b... more The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately.
Electric Power Systems Research, 2007
The topological properties of high-voltage electrical power transmission networks in several UE c... more The topological properties of high-voltage electrical power transmission networks in several UE countries (the Italian 380 kV, the French 400 kV and the Spanish 400 kV networks) have been studied from available data. An assessment of the vulnerability of the networks has been given by measuring the level of damage introduced by a controlled removal of links. Topological studies could be useful to make vulnerability assessment and to design specific action to reduce topological weaknesses. (V. Rosato).
Philosophical Magazine Part B, 1997
Equimolar solid solutions of Ag‒Cu and Co‒Cu were prepared by mechanical milling of the elements.... more Equimolar solid solutions of Ag‒Cu and Co‒Cu were prepared by mechanical milling of the elements. The structure and the thermodynamic properties of the resulting phases were analysed by X-ray diffraction, scanning electron microscopy and differential scanning calorimetry. Large mixing enthalpies (ΔH = 6–8kJg-atom and ΔH = 4–8kJg-atom for Ag-Cu and Co-Cu respectively) were measured in the alloyed phases. It is
A genetic algorithm for ground-state structure optimization of a Palladium atomic cluster has bee... more A genetic algorithm for ground-state structure optimization of a Palladium atomic cluster has been developed and ported on a SIMDMIMD parallel platform. The SIMD part of the parallel platform is represented by a Quadrics/APE100 consisting of 512 floating point units while the MIMD part is formed by a cluster of workstations. The proposed algorithm contains a part where the genetic operators are applied to the elements of the population and a part which performs a further local relaxation and the fitness calculation via Molecular Dynamics. These parts have been implemented on the MIMD part and on the SIMD one, respectively. Results have been compared to those generated by using a Simulated Annealing technique.
Materials Science and Engineering: A, 1995
ABSTRACT We report on the atomistic modelling and molecular dynamics simulation of several pallad... more ABSTRACT We report on the atomistic modelling and molecular dynamics simulation of several palladium nanostructures characterized by grains of various sizes. The atomistic modelling is based on the "simulated cluster condensation" technique, which allows the design of a nanostructure by the aggregation of atomic clusters of various sizes. The phase obtained upon thermal relaxation shows a density close to that resulting from the experimental "gas condensation" technique. The structural analysis has focused on the features induced by the presence of heterogeneous regions (grain boundaries and cavities) and on the resulting stress localization.
MRS Proceedings, 2000
ABSTRACT Tight Binding molecular dynamics simulations have been performed on single wall carbon n... more ABSTRACT Tight Binding molecular dynamics simulations have been performed on single wall carbon nanotubes, in order to evaluate thermal stability and the effect of the most relevant defects (the single vacancy and a Stone-Wales -SW- defect). The nanotubes are stable up to the graphite instability temperature. Both the considered defects have a large formation energy (EF(vac)=6.10 eV, EF(SW)= 5.55 eV).
The Journal of Chemical Physics, 2001
Lecture Notes in Computer Science, 1996
A genetic algorithm for ground-state structure optimization of a Palladium atomic cluster has bee... more A genetic algorithm for ground-state structure optimization of a Palladium atomic cluster has been developed and ported on a SIMDMIMD parallel platform. The SIMD part of the parallel platform is represented by a Quadrics/APE100 consisting of 512 floating point units while the MIMD part is formed by a cluster of workstations. The proposed algorithm contains a part where the genetic
Advances in Complex Systems, 2012
Systems of technological networks (so-called Critical Infrastructures) might undergo strong pertu... more Systems of technological networks (so-called Critical Infrastructures) might undergo strong perturbations leading to the reduction of their functionalities (crisis scenarios). Under perturbed conditions, infrastructures deliver their specific services in a range from a partial reduction up to a complete loss. Systems of complex technological networks (electrical, telecommunications, roads and railways, oil, gas and water pipelines etc.) are known to display
Lecture Notes in Computer Science, 2010
ABSTRACT We report on recent developments on stochastic chain modelling of inter-dependent networ... more ABSTRACT We report on recent developments on stochastic chain modelling of inter-dependent network infrastructures. The problem is approached in the spirit of the Leontief tradition within the framework of the Inoperability Input/Output Modelling [6] where, instead of dealing with the sector products, inoperabilities are introduced to describe the status of the global system.
Physical Review Letters, 1996
A mechanism to explain the complete oxidation of small metal clusters is proposed, based on the o... more A mechanism to explain the complete oxidation of small metal clusters is proposed, based on the occurrence of a mechanical instability driven by the expansion of the progressively oxidized cluster surface and the subsequent stress relaxation. Molecular dynamics simulations of spherical Pd clusters show that an expanded surface layer is capable of straining the inner core of the cluster up
Materials Science Forum, 1995
Nanostructured Materials, 1995
The present paper is aimed at introducing various methods for simulating nanophase materials at t... more The present paper is aimed at introducing various methods for simulating nanophase materials at the atomic level. Palladium is assumed as a prototype of a large class of materials, Thermodynamic, structural and mechanical properties have been computed and compared with the bulk ones in order to outline possible peculiarities of the simulated nanostructures. The role of the density as a critical parameter to classify the simulated samples have also been emphasized. Structural analysis have been performed by means of Voronoi-like polyhedra which also provide the localization of the disorder. Finally simulated cold compactification and heating process have been performed.
A model of the Italian 380 kV electrical transmission network has been analyzed under the topolog... more A model of the Italian 380 kV electrical transmission network has been analyzed under the topological and the functional viewpoints. The DC power flow model used to evaluate the power flux has been solved on the basis of input conditions (injected power - extracted power, line's reactances and the maximum flux capacity of each line) taken from real data. The
Physical Review Letters, 1996
A mechanism to explain the complete oxidation of small metal clusters is proposed, based on the o... more A mechanism to explain the complete oxidation of small metal clusters is proposed, based on the occurrence of a mechanical instability driven by the expansion of the progressively oxidized cluster surface and the subsequent stress relaxation. Molecular dynamics simulations of spherical Pd clusters show that an expanded surface layer is capable of straining the inner core of the cluster up
The grain-boundary free energy of a two-dimensional E 7 bicrystal has been estimated by combining... more The grain-boundary free energy of a two-dimensional E 7 bicrystal has been estimated by combining a quasiharmonic method based on evaluation of the partition function, with Monte Carlo energy sampling.
Self-organized complex systems can be analyzed in terms of their topological structure. This can ... more Self-organized complex systems can be analyzed in terms of their topological structure. This can unveil relevant properties related to robustness and efficiency. We show how a suitable combination of topological and spectral analysis may improve the understanding of the mechanisms and the driving force which lead to the spontaneous formation of the internet network at the Autonomous System level.
Physica A: Statistical Mechanics and its Applications, 2008
The Internet is one of the most interesting realizations of a "complex" network. As a non-supervi... more The Internet is one of the most interesting realizations of a "complex" network. As a non-supervised growing object, it allows the study of the selective pressure which drives the network to assume its current structure. The DIMES and the ROUTEVIEWS projects are ongoing projects aimed at evaluating the topological structure of the Internet (at the Autonomous System or AS grainlevel) on the basis of different types of measurements. The topological analysis of the networks produced by the two projects has allowed us to infer a growth mechanism which has been used to build up synthetic networks with similar properties. These networks have been used as test-beds for the implementation of a model of traffic dynamics, with the aim of assessing the ability of the Internet's topology to support the basic actions for data traffic handling. Results have been compared with those obtained by using a random network of similar size. The effects of some structural perturbations (arcs and nodes' removal, traffic localization) have been also evaluated in terms of the induced variations of the network's efficiency. The resulting scenario is consistent with the hypothesis that the structure of the Internet is only partially fit to host communication processes and that the intelligence of the TCP/IP protocol is partly needed to overcome some "structural" deficiencies.
Understanding Complex Systems, 2008
A Complex System's View of Critical Infrastructures Vittorio Rosato1, Ingve Simonsen3'4... more A Complex System's View of Critical Infrastructures Vittorio Rosato1, Ingve Simonsen3'4, Sandro Meloni1, Limor Issacharoff1'3, Karsten Peters2, Nils von Festenberg3, Dirk Helbing5 1 ENEA, Casaccia Research Center, Computing and ...
Journal of Computational Physics, 2001
The user has requested enhancement of the downloaded file. All in-text references underlined in b... more The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately.
Electric Power Systems Research, 2007
The topological properties of high-voltage electrical power transmission networks in several UE c... more The topological properties of high-voltage electrical power transmission networks in several UE countries (the Italian 380 kV, the French 400 kV and the Spanish 400 kV networks) have been studied from available data. An assessment of the vulnerability of the networks has been given by measuring the level of damage introduced by a controlled removal of links. Topological studies could be useful to make vulnerability assessment and to design specific action to reduce topological weaknesses. (V. Rosato).
Philosophical Magazine Part B, 1997
Equimolar solid solutions of Ag‒Cu and Co‒Cu were prepared by mechanical milling of the elements.... more Equimolar solid solutions of Ag‒Cu and Co‒Cu were prepared by mechanical milling of the elements. The structure and the thermodynamic properties of the resulting phases were analysed by X-ray diffraction, scanning electron microscopy and differential scanning calorimetry. Large mixing enthalpies (ΔH = 6–8kJg-atom and ΔH = 4–8kJg-atom for Ag-Cu and Co-Cu respectively) were measured in the alloyed phases. It is
A genetic algorithm for ground-state structure optimization of a Palladium atomic cluster has bee... more A genetic algorithm for ground-state structure optimization of a Palladium atomic cluster has been developed and ported on a SIMDMIMD parallel platform. The SIMD part of the parallel platform is represented by a Quadrics/APE100 consisting of 512 floating point units while the MIMD part is formed by a cluster of workstations. The proposed algorithm contains a part where the genetic operators are applied to the elements of the population and a part which performs a further local relaxation and the fitness calculation via Molecular Dynamics. These parts have been implemented on the MIMD part and on the SIMD one, respectively. Results have been compared to those generated by using a Simulated Annealing technique.
Materials Science and Engineering: A, 1995
ABSTRACT We report on the atomistic modelling and molecular dynamics simulation of several pallad... more ABSTRACT We report on the atomistic modelling and molecular dynamics simulation of several palladium nanostructures characterized by grains of various sizes. The atomistic modelling is based on the "simulated cluster condensation" technique, which allows the design of a nanostructure by the aggregation of atomic clusters of various sizes. The phase obtained upon thermal relaxation shows a density close to that resulting from the experimental "gas condensation" technique. The structural analysis has focused on the features induced by the presence of heterogeneous regions (grain boundaries and cavities) and on the resulting stress localization.
MRS Proceedings, 2000
ABSTRACT Tight Binding molecular dynamics simulations have been performed on single wall carbon n... more ABSTRACT Tight Binding molecular dynamics simulations have been performed on single wall carbon nanotubes, in order to evaluate thermal stability and the effect of the most relevant defects (the single vacancy and a Stone-Wales -SW- defect). The nanotubes are stable up to the graphite instability temperature. Both the considered defects have a large formation energy (EF(vac)=6.10 eV, EF(SW)= 5.55 eV).
The Journal of Chemical Physics, 2001
Lecture Notes in Computer Science, 1996
A genetic algorithm for ground-state structure optimization of a Palladium atomic cluster has bee... more A genetic algorithm for ground-state structure optimization of a Palladium atomic cluster has been developed and ported on a SIMDMIMD parallel platform. The SIMD part of the parallel platform is represented by a Quadrics/APE100 consisting of 512 floating point units while the MIMD part is formed by a cluster of workstations. The proposed algorithm contains a part where the genetic
Advances in Complex Systems, 2012
Systems of technological networks (so-called Critical Infrastructures) might undergo strong pertu... more Systems of technological networks (so-called Critical Infrastructures) might undergo strong perturbations leading to the reduction of their functionalities (crisis scenarios). Under perturbed conditions, infrastructures deliver their specific services in a range from a partial reduction up to a complete loss. Systems of complex technological networks (electrical, telecommunications, roads and railways, oil, gas and water pipelines etc.) are known to display
Lecture Notes in Computer Science, 2010
ABSTRACT We report on recent developments on stochastic chain modelling of inter-dependent networ... more ABSTRACT We report on recent developments on stochastic chain modelling of inter-dependent network infrastructures. The problem is approached in the spirit of the Leontief tradition within the framework of the Inoperability Input/Output Modelling [6] where, instead of dealing with the sector products, inoperabilities are introduced to describe the status of the global system.
Physical Review Letters, 1996
A mechanism to explain the complete oxidation of small metal clusters is proposed, based on the o... more A mechanism to explain the complete oxidation of small metal clusters is proposed, based on the occurrence of a mechanical instability driven by the expansion of the progressively oxidized cluster surface and the subsequent stress relaxation. Molecular dynamics simulations of spherical Pd clusters show that an expanded surface layer is capable of straining the inner core of the cluster up
Materials Science Forum, 1995
Nanostructured Materials, 1995
The present paper is aimed at introducing various methods for simulating nanophase materials at t... more The present paper is aimed at introducing various methods for simulating nanophase materials at the atomic level. Palladium is assumed as a prototype of a large class of materials, Thermodynamic, structural and mechanical properties have been computed and compared with the bulk ones in order to outline possible peculiarities of the simulated nanostructures. The role of the density as a critical parameter to classify the simulated samples have also been emphasized. Structural analysis have been performed by means of Voronoi-like polyhedra which also provide the localization of the disorder. Finally simulated cold compactification and heating process have been performed.
A model of the Italian 380 kV electrical transmission network has been analyzed under the topolog... more A model of the Italian 380 kV electrical transmission network has been analyzed under the topological and the functional viewpoints. The DC power flow model used to evaluate the power flux has been solved on the basis of input conditions (injected power - extracted power, line's reactances and the maximum flux capacity of each line) taken from real data. The
Physical Review Letters, 1996
A mechanism to explain the complete oxidation of small metal clusters is proposed, based on the o... more A mechanism to explain the complete oxidation of small metal clusters is proposed, based on the occurrence of a mechanical instability driven by the expansion of the progressively oxidized cluster surface and the subsequent stress relaxation. Molecular dynamics simulations of spherical Pd clusters show that an expanded surface layer is capable of straining the inner core of the cluster up
The grain-boundary free energy of a two-dimensional E 7 bicrystal has been estimated by combining... more The grain-boundary free energy of a two-dimensional E 7 bicrystal has been estimated by combining a quasiharmonic method based on evaluation of the partition function, with Monte Carlo energy sampling.
Self-organized complex systems can be analyzed in terms of their topological structure. This can ... more Self-organized complex systems can be analyzed in terms of their topological structure. This can unveil relevant properties related to robustness and efficiency. We show how a suitable combination of topological and spectral analysis may improve the understanding of the mechanisms and the driving force which lead to the spontaneous formation of the internet network at the Autonomous System level.