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1.

001-es BibID:BIBFORM106122
035-os BibID:(cikkazonosító)063121 (WoS)000812354100003 (Scopus)85132037842
Első szerző:Batool, Attia
Cím:Temporal evolution of failure avalanches of the fiber bundle model on complex networks / Attia Batool, Zsuzsa Danku, Gergő Pál, Ferenc Kun
Dátum:2022
ISSN:1054-1500 1089-7682
Megjegyzések:We investigate how the interplay of the topology of the network of load transmitting connections and the amount of disorder of the strength of the connected elements determines the temporal evolution of failure cascades driven by the redistribution of load following local failure events. We use the fiber bundle model of materials' breakdown assigning fibers to the sites of a square lattice, which is then randomly rewired using the Watts?Strogatz technique. Gradually increasing the rewiring probability, we demonstrate that the bundle undergoes a transition from the localized to the mean field universality class of breakdown phenomena. Computer simulations revealed that both the size and the duration of failure cascades are power law distributed on all network topologies with a crossover between two regimes of different exponents. The temporal evolution of cascades is described by a parabolic profile with a right handed asymmetry, which implies that cascades start slowly, then accelerate, and eventually stop suddenly. The degree of asymmetry proved to be characteristic of the network topology gradually decreasing with increasing rewiring probability. Reducing the variance of fibers' strength, the exponents of the size and the duration distribution of cascades increase in the localized regime of the failure process, while the localized to mean field transition becomes more abrupt. The consistency of the results is supported by a scaling analysis relating the characteristic exponents of the statistics and dynamics of cascades.
Tárgyszavak:Természettudományok Fizikai tudományok kutatási jelentés
folyóiratcikk
Megjelenés:Chaos. - 32 : 6 (2022), p. 1-10. -
További szerzők:Danku Zsuzsa (1984-) (fizikus) Pál Gergő (1987-) (fizikus) Kun Ferenc (1966-) (fizikus)
Pályázati támogatás:EFOP-3.6.1-16-2016-00022
EFOP
K 119967
Egyéb
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2.

001-es BibID:BIBFORM106120
035-os BibID:(cikkazonosító)112190 (WoS)000881271500010 (Scopus)85129920978
Első szerző:Batool, Attia
Cím:Transition from localized to mean field behaviour of cascading failures in the fiber bundle model on complex networks / Attia Batool, Gergő Pál, Zsuzsa Danku, Ferenc Kun
Dátum:2022
ISSN:0960-0779
Megjegyzések:We study the failure process of fiber bundles on complex networks focusing on the effect of the degree of disorder of fibers' strength on the transition from localized to mean field behaviour. Starting from a regular square lattice we apply the Watts-Strogatz rewiring technique to introduce long range random connections in the load transmission network and analyze how the ultimate strength of the bundle and the statistics of the size of failure cascades change when the rewiring probability is gradually increased. Our calculations revealed that the degree of strength disorder of nodes of the network has a substantial effect on the localized to mean field transition. In particular, we show that the transition sets on at a finite value of the rewiring probability, which shifts to higher values as the degree of disorder is reduced. The transition is limited to a well defined range of disorder, so that there exists a threshold disorder of nodes' strength below which the randomization of the network structure does not provide any improvement neither of the overall load bearing capacity nor of the cascade tolerance of the system. At low strength disorder the fully random network is the most stable one, while at high disorder best cascade tolerance is obtained at a lower structural randomness. Based on the interplay of the network structure and strength disorder we construct an analytical argument which provides a reasonable description of the numerical findings.
Tárgyszavak:Természettudományok Fizikai tudományok kutatási jelentés
folyóiratcikk
Megjelenés:Chaos Solitons & Fractals. - 159 (2022), p. 1-11. -
További szerzők:Pál Gergő (1987-) (fizikus) Danku Zsuzsa (1984-) (fizikus) Kun Ferenc (1966-) (fizikus)
Pályázati támogatás:EFOP-3.6.1-16-2016-00022
EFOP
K 11996
Egyéb
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Intézményi repozitóriumban (DEA) tárolt változat
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3.

001-es BibID:BIBFORM104097
035-os BibID:(cikkazonosító)042116 (WOS)000579816300001 (Scopus)85093109330
Első szerző:Batool, Attia
Cím:Impact-induced transition from damage to perforation / Attia Batool, Gergő Pál, Ferenc Kun
Dátum:2020
ISSN:2470-0045 2470-0053
Megjegyzések:We investigate the impact-induced damage and fracture of a bar-shaped specimen of heterogeneous materials focusing on how the system approaches perforation as the impact energy is gradually increased. A simple model is constructed which represents the bar as two rigid blocks coupled by a breakable interface with disordered local strength. The bar is clamped at the two ends, and the fracture process is initiated by an impactor hitting the bar in the middle. Our calculations revealed that depending on the imparted energy, the system has two phases: at low impact energies the bar suffers damage but keeps its integrity, while at sufficiently high energies, complete perforation occurs. We demonstrate that the transition from damage to perforation occurs analogous to continuous phase transitions. Approaching the critical point from below, the intact fraction of the interface goes to zero, while the deformation rate of the bar diverges according to power laws as function of the distance from the critical energy. As the degree of disorder increases, farther from the transition point the critical exponents agree with their zero disorder counterparts; however, close to the critical point a crossover occurs to a higher exponent.
Tárgyszavak:Természettudományok Fizikai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Megjelenés:Physical Review E. - 102 : 4 (2020), p. 1-11. -
További szerzők:Pál Gergő (1987-) (fizikus) Kun Ferenc (1966-) (fizikus)
Pályázati támogatás:EFOP-3.6.1-16-2016-00022
EFOP
NKFIH-K-119967
Egyéb
ED18-1-2019-0028
Egyéb
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Intézményi repozitóriumban (DEA) tárolt változat
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4.

001-es BibID:BIBFORM116065
035-os BibID:(cikkazonosító)128994 (Scopus)85163744348
Első szerző:Danku Zsuzsa (fizikus)
Cím:Size scaling of failure strength at high disorder / Zsuzsa Danku, Gergő Pál, Ferenc Kun
Dátum:2023
ISSN:0378-4371
Megjegyzések:We investigate how the macroscopic response and the size scaling of the ultimate strength of materials change when their local strength is sampled from a fat-tailed distribution and the degree of disorder is varied in a broad range. Using equal and localized load sharing in a fiber bundle model, we demonstrate that a transition occurs from a perfectly brittle to a quasi-brittle behavior as the amount of disorder is gradually increased. When the load sharing is localized the high load concentration around failed regions make the system more prone to failure so that a higher degree of disorder is required for stabilization. Increasing the system size at a fixed degree of disorder an astonishing size effect is obtained: at small sizes the ultimate strength of the system increases with its size, the usual decreasing behavior sets on only beyond a characteristic system size. The increasing regime of the size effect prevails even for localized load sharing, however, above the characteristic system size the load concentration results in a substantial strength reduction compared to equal load sharing. We show that an adequate explanation of the results can be obtained based on the extreme order statistics of fibers' strength.
Tárgyszavak:Természettudományok Fizikai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Fiber bundle model
Fracture
Heterogeneous materials
Size scaling
Ultimate strength
Megjelenés:Physica A-Statistical Mechanics And Its Applications. - 624 (2023), p. 1-8. -
További szerzők:Pál Gergő (1987-) (fizikus) Kun Ferenc (1966-) (fizikus)
Pályázati támogatás:EFOP-3.6.1-16-2016-00022
EFOP
NKFIH K 119967
Egyéb
NKFIH TKP2020-NKA-04
Egyéb
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Intézményi repozitóriumban (DEA) tárolt változat
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5.

001-es BibID:BIBFORM100227
035-os BibID:(cikkazonosító)127015 (WoS)000793673500016 (Scopus)85125850119
Első szerző:Kádár Viktória (okleveles anyagkutató)
Cím:Approach to failure through record breaking avalanches in a heterogeneous stress field / Kádár Viktória, Danku Zsuzsa, Pál Gergő, Kun Ferenc
Dátum:2022
ISSN:0378-4371
Megjegyzések:We study how the competition of the disordered local strength and of the evolving inhomogeneous stress field affects the evolution of the series of breaking avalanches accompanying the fracture of heterogeneous materials. To generate fracture processes, we use a fiber bundle model of localized load sharing where the degree of strength disorder is controlled by varying two parameters of the distribution of the breaking threshold of fibers. Analyzing the record statistics of avalanches of breaking fibers, we demonstrate that both for low and high disorders the series of crackling events remains stationary until global failure making the collapse of the system unpredictable. Based on computer simulations, we determine a region of the parameter plane of strength disorder where global failure is preceded by an accelerating breaking activity. We show that the record avalanche with the longest lifetime can be used to identify the onset of acceleration of the fracture process towards the catastrophic failure. Comparison of the results to their equal load sharing counterparts reveals that the accelerating regime is shorter than in case of a homogeneous stress field due to the higher degree of brittleness of the system caused by stress localization.
Tárgyszavak:Természettudományok Fizikai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
crackling noise
failure
fracture
ultimate failure
fiber bundle model
record statistics
Megjelenés:Physica A-Statistical Mechanics And Its Applications. - 594 (2022), p. 1-12. -
További szerzők:Danku Zsuzsa (1984-) (fizikus) Pál Gergő (1987-) (fizikus) Kun Ferenc (1966-) (fizikus)
Pályázati támogatás:UNKP-20-3
Egyéb
K 119967
Egyéb
2020-4.1.1-TKP2020
Egyéb
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Intézményi repozitóriumban (DEA) tárolt változat
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6.

001-es BibID:BIBFORM093732
035-os BibID:(Cikkazonosító)2508 (WOS)000562887700005 (Scopus)85079336571
Első szerző:Kádár Viktória (okleveles anyagkutató)
Cím:Record statistics of bursts signals the onset of acceleration towards failure / Kádár Viktória, Pál Gergő, Kun Ferenc
Dátum:2020
ISSN:2045-2322
Megjegyzések:Forecasting the imminent catastrophic failure has a high importance for a large variety of systems from the collapse of engineering constructions, through the emergence of landslides and earthquakes, to volcanic eruptions. Failure forecast methods predict the lifetime of the system based on the time-to-failure power law of observables describing the final acceleration towards failure. We show that the statistics of records of the event series of breaking bursts, accompanying the failure process, provides a powerful tool to detect the onset of acceleration, as an early warning of the impending catastrophe. We focus on the fracture of heterogeneous materials using a fiber bundle model, which exhibits transitions between perfectly brittle, quasi-brittle, and ductile behaviors as the amount of disorder is increased. Analyzing the lifetime of record size bursts, we demonstrate that the acceleration starts at a characteristic record rank, below which record breaking slows down due to the dominance of disorder in fracturing, while above it stress redistribution gives rise to an enhanced triggering of bursts and acceleration of the dynamics. The emergence of this signal depends on the degree of disorder making both highly brittle fracture of low disorder materials, and ductile fracture of strongly disordered ones, unpredictable.
Tárgyszavak:Természettudományok Fizikai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
előrejelzés
törés
rekord statisztika
rendezetlenség
Megjelenés:Scientific Reports. - 10 : 1 (2020), p. 1-12. -
További szerzők:Pál Gergő (1987-) (fizikus) Kun Ferenc (1966-) (fizikus)
Pályázati támogatás:EFOP-3.6.1-16-2016-00022
EFOP
NKFIH K-16 K119967
Egyéb
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Intézményi repozitóriumban (DEA) tárolt változat
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7.

001-es BibID:BIBFORM078785
035-os BibID:(cikkazonosító)20170393 (WoS)000451219600008 (Scopus)85057260752
Első szerző:Kun Ferenc (fizikus)
Cím:Effect of disorder on the spatial structure of damage in slowly compressed porous rocks / Ferenc Kun, Gergő Pál, Imre Varga, Ian G. Main
Dátum:2019
ISSN:1364-503X
Megjegyzések:Faults and damage zone properties control a range of important phenomena, from the hydraulic properties of underground reservoirs to the physics of earthquakes on a larger scale. Here, we investigate the effect of disorder of porous rocks on the spatial structure of damage emerging under compression. Model rock samples are numerically generated by sedimenting particles where the amount of disorder is controlled by the particle size distribution. To obtain damage bands with a sufficiently large length along axis, we performed simulations of ?Brazilian'-type compression tests of cylindrical samples. As failure is approached, damage localization leads to the formation of two conjugate shear bands. The orientation angle of bands to the loading direction increases with disorder, implying a decrease in the internal coefficient of friction. The width of the damage band scales as a power law of the degree of disorder. Inside the damage band, the sample is crushed into a large number of pieces with a power law mass distribution. The shape of fragments undergoes a crossover at a disorder-dependent size from the isotropy of small pieces to the anisotropic flattened form of the large ones. The results provide important constraints in understanding the role of disorder in geological fractures.
Tárgyszavak:Műszaki tudományok Informatikai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
damage band
fault
compression
fragmentation
disorder
discrete element simulation
Megjelenés:Philosophical Transactions Of The Royal Society A-Mathematical Physical And Engineering Sciences. - 377 : 2136 (2019), p. 1-14. -
További szerzők:Pál Gergő (1987-) (fizikus) Varga Imre (1979-) (fizikus, informatikus) Main, Ian G.
Pályázati támogatás:EFOP-3.6.1-16-2016-00022
EFOP
NKFIH K-16 K 119967
egyéb
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Intézményi repozitóriumban (DEA) tárolt változat
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8.

001-es BibID:BIBFORM116492
035-os BibID:(cikkazonosító)19733 (WoS)001104940600020 (Scopus)85176441719
Első szerző:Pál Gergő (fizikus)
Cím:Scaling laws of failure dynamics on complex networks / Gergő Pál, Zsuzsa Danku, Attia Batool, Viktória Kádár, NaokiYoshioka, Nobuyasu Ito, Géza Ódor, Ferenc Kun
Dátum:2023
ISSN:2045-2322
Megjegyzések:The topology of the network of load transmitting connections plays an essential role in the cascading failure dynamics of complex systems driven by the redistribution of load after local breakdown events. In particular, as the network structure is gradually tuned from regular to completely random a transition occurs from the localized to mean field behavior of failure spreading. Based on finite size scaling in the fiber bundle model of failure phenomena, here we demonstrate that outside the localized regime, the load bearing capacity and damage tolerance on the macro-scale, and the statistics of clusters of failed nodes on the micro-scale obey scaling laws with exponents which depend on the topology of the load transmission network and on the degree of disorder of the strength of nodes. Most notably, we show that the spatial structure of damage governs the emergence of the localized to mean field transition: as the network gets gradually randomized failed clusters formed on locally regular patches merge through long range links generating a percolation like transition which reduces the load concentration on the network. The results may help to design network structures with an improved robustness against cascading failure.
Tárgyszavak:Természettudományok Fizikai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
complex networks
scaling laws
Megjelenés:Scientific Reports. - 13 : 1 (2023), p. 1-12. -
További szerzők:Danku Zsuzsa (1984-) (fizikus) Batool, Attia Kádár Viktória (1992-) (okleveles anyagkutató) Yoshioka, Naoki Ito, Nobuyasu Ódor Géza Kun Ferenc (1966-) (fizikus)
Pályázati támogatás:EFOP-3.6.1-16-2016-00022
EFOP
K 119967
OTKA
K 128989
OTKA
TKP2020-NKA-0
Egyéb
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Intézményi repozitóriumban (DEA) tárolt változat
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9.

001-es BibID:BIBFORM098600
035-os BibID:(Cikkazonosító)20661 (WOS)000709050100003 (Scopus)85117682381
Első szerző:Pál Gergő (fizikus)
Cím:Curvature flows, scaling laws and the geometry of attrition under impacts / Pál Gergő, Domokos Gábor, Kun Ferenc
Dátum:2021
ISSN:2045-2322
Tárgyszavak:Természettudományok Fizikai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Megjelenés:Scientific Reports. - 11 : 1 (2021), p. 1-8. -
További szerzők:Domokos Gábor Kun Ferenc (1966-) (fizikus)
Pályázati támogatás:EFOP-3.6.1-16-2016-00022
EFOP
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Intézményi repozitóriumban (DEA) tárolt változat
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10.

001-es BibID:BIBFORM069496
Első szerző:Pál Gergő (fizikus)
Cím:Effect of spatial dimension on impact fragmentation / G. Pál, I. Varga, T. Kadono, F. Kun
Dátum:2013
Megjegyzések:We study the impact fragmentation of heterogeneous materi-als in three dimensions varying the shape of the specimen fromquasi two-dimensional plates to three-dimensional cubic bulkobjects. Based on large scale molecular dynamics simulationswe show that the damage-fragmentation transition prevails foreach shapes, however, the mechanism of breakup and the re-sulting mass distribution of fragments have strong dimensionaldependence. For plate-like objects in the fragmented regimepower law mass distributions are obtained, however, the ex-ponent is not universal, it increases with the imparted energy.For three-dimensional bulk specimens the energy dependencegradually disappears and a universal mass distribution emerges.Our detailed analysis revealed that the breakup process is theresult of three competing mechanisms which all lead to uni-versal mass distributions, however, their overall contributionschange with the impact energy.
Tárgyszavak:Természettudományok Fizikai tudományok idegen nyelvű folyóiratközlemény hazai lapban
fragmentation
discrete element model
dimensionality
Doktori iskola
Megjelenés:Acta Physica Debrecina 47 (2013), p. 129-135. -
További szerzők:Varga Imre (1979-) (fizikus, informatikus) Kadono T. Kun Ferenc (1966-) (fizikus)
Pályázati támogatás:TÁMOP-4.2.2.A-11/1/KONV-2012-0036
TÁMOP
TÁMOP-4.2.2/B-10/1-2010-0024
TÁMOP
Fizikai Tudományok Doktori Iskola
TAMOP4.2.4.A/2-11-1-2012- 0001
TÁMOP
OTKA K84157
OTKA
ERANET HU 09-1-2011-0002
Egyéb
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Intézményi repozitóriumban (DEA) tárolt változat
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11.

001-es BibID:BIBFORM069501
035-os BibID:(Scopus)84996865562 (WoS)000388278300006
Első szerző:Pál Gergő (fizikus)
Cím:Fragmentation and shear band formation by slow compression of brittle porous media / Gergő Pál, Zoltán Jánosi, Ferenc Kun, Ian G. Main
Dátum:2016
ISSN:2470-0045 2470-0053
Megjegyzések:Localized fragmentation is an important phenomenon associated with the formation of shear bands and faults ingranular media. It can be studied by empirical observation, by laboratory experiment, or by numerical simulation.Here we investigate the spatial structure and statistics of fragmentation using discrete element simulations of thestrain-controlled uniaxial compression of cylindrical samples of different finite size. As the system approachesfailure, damage localizes in a narrow shear band or synthetic fault "gouge" containing a large number of poorlysorted noncohesive fragments on a broad bandwidth of scales, with properties similar to those of natural andexperimental faults. We determine the position and orientation of the central fault plane, the width of the shearband, and the spatial and mass distribution of fragments. The relative width of the shear band decreases as apower law of the system size, and the probability distribution of the angle of the central fault plane converges toaround 30 degrees, representing an internal coefficient of friction of 0.7 or so. The mass of fragments is powerlaw distributed, with an exponent that does not depend on scale, and is near that inferred for experimental andnatural fault gouges. The fragments are in general angular, with a clear self-affine geometry. The consistencyof this model with experimental and field results confirms the critical roles of preexisting heterogeneity, elasticinteractions, and finite system size to grain size ratio on the development of shear bands and faults in porousmedia.
Tárgyszavak:Természettudományok Fizikai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
shear band
porous material
discrete element model
quasi-static fragmentation
Megjelenés:Physical Review E. - 94 : 5 (2016), p. 053003-1 - 053003-8. -
További szerzők:Jánosi Zoltán Kun Ferenc (1966-) (fizikus) Main, Ian G.
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Intézményi repozitóriumban (DEA) tárolt változat
Borító:

12.

001-es BibID:BIBFORM069498
035-os BibID:(Scopus)84963599543 (WoS)000373108700005
Első szerző:Pál Gergő (fizikus)
Cím:Record-breaking events during the compressive failure of porous materials / Gergő Pál, Frank Raischel, Sabine Lennartz-Sassinek, Ferenc Kun, Ian G. Main
Dátum:2016
ISSN:2470-0045 2470-0053
Megjegyzések:An accurate understanding of the interplay between random and deterministic processes in generating extremeevents is of critical importance in many fields, from forecasting extreme meteorological events to the catastrophicfailure of materials and in the Earth. Here we investigate the statistics of record-breaking events in the time seriesof crackling noise generated by local rupture events during the compressive failure of porous materials. Theevents are generated by computer simulations of the uniaxial compression of cylindrical samples in a discreteelement model of sedimentary rocks that closely resemble those of real experiments. The number of recordsgrows initially as a decelerating power law of the number of events, followed by an acceleration immediatelyprior to failure. The distribution of the size and lifetime of records are power laws with relatively low exponents.We demonstrate the existence of a characteristic record rank k ? , which separates the two regimes of the timeevolution. Up to this rank deceleration occurs due to the effect of random disorder. Record breaking thenaccelerates towards macroscopic failure, when physical interactions leading to spatial and temporal correlationsdominate the location and timing of local ruptures. The size distribution of records of different ranks has auniversal form independent of the record rank. Subsequences of events that occur between consecutive recordsare characterized by a power-law size distribution, with an exponent which decreases as failure is approached.High-rank records are preceded by smaller events of increasing size and waiting time between consecutive eventsand they are followed by a relaxation process. As a reference, surrogate time series are generated by reshufflingthe event times. The record statistics of the uncorrelated surrogates agrees very well with the correspondingpredictions of independent identically distributed random variables, which confirms that temporal and spatialcorrelation in the crackling noise is responsible for the observed unique behavior. In principle the results couldbe used to improve forecasting of catastrophic failure events, if they can be observed reliably in real time.
Tárgyszavak:Természettudományok Fizikai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
shear band formation
earthquake
macroscopic failure
discrete element model
Megjelenés:Physical Review E. - 93 : 3 (2016), p. 033006-1 - 033006-10. -
További szerzők:Raischel, Frank Lennartz-Sassinek, Sabine Kun Ferenc (1966-) (fizikus) Main, Ian G.
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