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1.
Combustion simulation in the secondary chamber of a pilot-scale incinerator
Niko Samec, Filip Kokalj, Jyh-Yan Chen, 2007, izvirni znanstveni članek

Opis: A numerical analysis of combustion in the secondary chamber (thermoreactor) ofa two-stage pilot scale incinerator using computational fluid dynamics (CFD)is presented in detail. Various versions of the CFD program package CFX were used, which offer different combustion models for specific types and forms of combustion processes. The present study was focused on those physicalconditions that assure complete combustion, that is, temperature, residence time, and turbulent mixing. The selection of an appropriate combustion model was based on a comparison of the numerical results and experimental values of some combustion macro parameters in a thermoreactor. Combustion models based on one-step bimolecular chemical reaction and models based on multistep reactions were used. These models enabled a more detailed prediction of the combustion process in the secondary chamber of a pilot-scaleincinerator. The products of incomplete combustion that are significantly important for the designing and optimization of combustion devices can be predicted by applying multistep reaction models more accurately, especially in a transient regime of combustion.
Ključne besede: waste incineration, numerical modeling, combustion models, incinerator chamber, CFX, CFD, computational fluid dynamics
Objavljeno: 31.05.2012; Ogledov: 1223; Prenosov: 26
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2.
Linearizability conditions of a time-reversible quartic-like system
Xingwu Chen, Wentao Huang, Valery Romanovski, Weinian Zhang, 2011, izvirni znanstveni članek

Opis: In this paper we study the linearizability problem of polynomial-like complex differential systems. We give a reduction of linearizability problem of such non-polynomial systems to the problem of polynomial systems. Applying this reduction, we find some linearizability conditions for a time-reversible quartic-like complex system and derive from them conditions of isochronous center for the corresponding real system.
Ključne besede: mathematics, reversibility, isochronous center
Objavljeno: 07.06.2012; Ogledov: 573; Prenosov: 35
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3.
Linearizability conditions of time-reversible cubic systems
Xingwu Chen, Valery Romanovski, 2010, izvirni znanstveni članek

Opis: In this paper we present the necessary and sufficient conditions for linearizability of the planar time-reversible cubic complex system ▫$dot{x}=x+P(x,y)$▫, ▫$dot{y}=-y+Q(x,y)$▫. From these conditions, the necessary and sufficient conditions for the origin to be an isochronous center of the time-reversible cubic real system ▫$dot{u}=-v+F(u,v)$▫, ▫$dot{v}=u+G(u,v)$▫ can be obtained. Thus, the isochronous center problem of time-reversible cubic systems is solved completely.
Ključne besede: mathematics
Objavljeno: 07.06.2012; Ogledov: 610; Prenosov: 31
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Adaptive and bounded investment returns promote cooperation in spatial public goods games
Xiaojie Chen, Yongkui Liu, Yonghui Zhou, Long Wang, Matjaž Perc, 2012, izvirni znanstveni članek

Opis: The public goods game is one of the most famous models for studying the evolution of cooperation in sizable groups. The multiplication factor in this game can characterize the investment return from the public good, which may be variable depending on the interactive environment in realistic situations. Instead of using the same universal value, here we consider that the multiplication factor in each group is updated based on the differences between the local and global interactive environments in the spatial public goods game, but meanwhile limited to within a certain range. We find that the adaptive and bounded investment returns can significantly promote cooperation. In particular, full cooperation can be achieved for high feedback strength when appropriate limitation is set for the investment return. Also, we show that the fraction of cooperators in the whole population can become larger if the lower and upper limits of the multiplication factor are increased. Furthermore, in comparison to the traditionally spatial public goods game where the multiplication factor in each group is identical and fixed, we find that cooperation can be better promoted if the multiplication factor is constrained to adjust between one and the group size in our model. Our results highlight the importance of the locally adaptive and bounded investment returns for the emergence and dominance of cooperative behavior in structured populations.
Ključne besede: cooperation, public goods, social dilemmas, physics of social systems
Objavljeno: 19.06.2017; Ogledov: 215; Prenosov: 98
.pdf Celotno besedilo (590,51 KB)
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6.
Evolution of public cooperation in a monitored society with implicated punishment and within-group enforcement
Xiaojie Chen, Tatsuya Sasaki, Matjaž Perc, 2015, izvirni znanstveni članek

Opis: Monitoring with implicated punishment is common in human societies to avert freeriding on common goods. But is it effective in promoting public cooperation? We show that the introduction of monitoring and implicated punishment is indeed effective, as it transforms the public goods game to a coordination game, thus rendering cooperation viable in infinite and finite well-mixed populations. We also show that the addition of within-group enforcement further promotes the evolution of public cooperation. However, although the group size in this context has nonlinear effects on collective action, an intermediate group size is least conductive to cooperative behaviour. This contradicts recent field observations, where an intermediate group size was declared optimal with the conjecture that group-size effects and within-group enforcement are responsible. Our theoretical research thus clarifies key aspects of monitoring with implicated punishment in human societies, and additionally, it reveals fundamental group-size effects that facilitate prosocial collective action.
Ključne besede: cooperation, public goods, punishment, sustainable development, physics of social systems
Objavljeno: 23.06.2017; Ogledov: 231; Prenosov: 91
.pdf Celotno besedilo (1,50 MB)
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7.
Win-stay-lose-learn promotes cooperation in the spatial prisoner's dilemma game
Yongkui Liu, Xiaojie Chen, Lin Zhang, Long Wang, Matjaž Perc, 2012, izvirni znanstveni članek

Opis: Holding on to one's strategy is natural and common if the later warrants success and satisfaction. This goes against widespread simulation practices of evolutionary games, where players frequently consider changing their strategy even though their payoffs may be marginally different than those of the other players. Inspired by this observation, we introduce an aspiration-based win-stay-lose-learn strategy updating rule into the spatial prisoner's dilemma game. The rule is simple and intuitive, foreseeing strategy changes only by dissatisfied players, who then attempt to adopt the strategy of one of their nearest neighbors, while the strategies of satisfied players are not subject to change. We find that the proposed winstay-lose-learn rule promotes the evolution of cooperation, and it does so very robustly and independently of the initial conditions. In fact, we show that even a minute initial fraction of cooperators may be sufficient to eventually secure a highly cooperative final state. In addition to extensive simulation results that support our conclusions, we also present results obtained by means of the pair approximation of the studied game. Our findings continue the success story of related winstay strategy updating rules, and by doing so reveal new ways of resolving the prisoner's dilemma.
Ključne besede: social dilemmas, prisoner's dilemma, cooperation, networks
Objavljeno: 19.06.2017; Ogledov: 278; Prenosov: 84
.pdf Celotno besedilo (390,56 KB)
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8.
Beyond pairwise strategy updating in the prisoner's dilemma game
Xiaofeng Wang, Matjaž Perc, Yongkui Liu, Xiaojie Chen, Long Wang, 2012, izvirni znanstveni članek

Opis: In spatial games players typically alter their strategy by imitating the most successful or one randomly selected neighbor. Since a single neighbor is taken as reference, the information stemming from other neighbors is neglected, which begets the consideration of alternative, possibly more realistic approaches. Here we show that strategy changes inspired not only by the performance of individual neighbors but rather by entire neighborhoods introduce a qualitatively different evolutionary dynamics that is able to support the stable existence of very small cooperative clusters. This leads to phase diagrams that differ significantly from those obtained by means of pairwise strategy updating. In particular, the survivability of cooperators is possible even by high temptations to defect and over a much wider uncertainty range. We support the simulation results by means of pair approximations and analysis of spatial patterns, which jointly highlight the importance of local information for the resolution of social dilemmas.
Ključne besede: cooperation, social dilemma, wisdom of crowds, phase transitions, physics of social systems
Objavljeno: 23.06.2017; Ogledov: 150; Prenosov: 87
.pdf Celotno besedilo (825,96 KB)
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9.
Excessive abundance of common resources deters social responsibility
Xiaojie Chen, Matjaž Perc, 2014, izvirni znanstveni članek

Opis: We study the evolution of cooperation in the collective-risk social dilemma game, where the risk is determined by a collective target that must be reached with individual contributions. All players initially receive endowments from the available amount of common resources. While cooperators contribute part of their endowment to the collective target, defectors do not. If the target is not reached, the endowments of all players are lost. In our model, we introduce a feedback between the amount of common resources and the contributions of cooperators. We show that cooperation can be sustained only if the common resources are preserved but never excessively abound. This, however, requires a delicate balance between the amount of common resources that initially exist, and the amount cooperators contribute to the collective target. Exceeding critical thresholds in either of the two amounts leads to loss of cooperation, and consequently to the depletion of common resources.
Ključne besede: social dilemma, evolutionary games, public goods, abundance, phase transitions, physics of social systems
Objavljeno: 23.06.2017; Ogledov: 290; Prenosov: 97
.pdf Celotno besedilo (950,12 KB)
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10.
Probabilistic sharing solves the problem of costly punishment
Xiaojie Chen, Attila Szolnoki, Matjaž Perc, 2014, izvirni znanstveni članek

Opis: Cooperators that refuse to participate in sanctioning defectors create the secondorder free-rider problem. Such cooperators will not be punished because they contribute to the public good, but they also eschew the costs associated with punishing defectors. Altruistic punishers - those that cooperate and punish - are at a disadvantage, and it is puzzling how such behaviour has evolved. We show that sharing the responsibility to sanction defectors rather than relying on certain individuals to do so permanently can solve the problem of costly punishment. Inspired by the fact that humans have strong but also emotional tendencies for fair play, we consider probabilistic sanctioning as the simplest way of distributing the duty. In well-mixed populations the public goods game is transformed into a coordination game with full cooperation and defection as the two stable equilibria, while in structured populations pattern formation supports additional counterintuitive solutions that are reminiscent of Parrondoʼs paradox.
Ključne besede: social dynamics, networks, punishment, public goods, econophysics
Objavljeno: 03.07.2017; Ogledov: 218; Prenosov: 115
.pdf Celotno besedilo (1,52 MB)
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