Search results for "Self-organized criticality"

showing 3 items of 3 documents

Threshold rule and scaling behavior in a multi-agent supply chain

2010

In this paper an agent-based model of self organized criticality is developed in a network economy characterized by lead time and a threshold behavior of firms. Instead of considering the aggregate production of the economy as a whole, we focus on both the propagation and amplification effects of a demand shock in the sectorial productions of a multi-agent supply chain. We study a static network structure representing a relation of firms in a lower-upper stream in an industrial organization. In our model, the individual (R, nQ) policies play an important role in generating a propagation effect across the different layers of the economy, and the propagation turns into the large fluctuations …

Agent-based modelComputer scienceSupply chainSelf organized criticalityagent-based modelNetwork economySelf-organized criticalityReorder pointbullwhip effectSettore SECS-S/06 -Metodi Mat. dell'Economia e d. Scienze Attuariali e Finanz.Demand shockBullwhip effectEconometricsLead time
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A coupled map as a model of the dynamics of the magnetotail current sheet

2001

Abstract A magnetic field model of the magnetotail current sheet in the form of a coupled-map lattice (CML) is presented. It is continuously driven (“running”) and based on the MHD diffusion equation. Solar wind vBS data (solar wind speed multiplied by the southward component of IMF) are used for driving the model, and it is shown to exhibit perturbations (avalanches) with power-law scalings in their distributions of duration and size. Such distributions may indicate self-organized critical (SOC) behavior. Furthermore, it is shown that the power spectra of the model outputs are of bicolor power-law form with different slopes for high and low frequencies. Although the “running” model gives p…

PhysicsAtmospheric ScienceDiffusion equationMechanicsPower lawSelf-organized criticalityMagnetic fieldSolar windCurrent sheetGeophysicsClassical mechanicsSpace and Planetary ScienceElectrical resistivity and conductivityPhysics::Space PhysicsMagnetohydrodynamicsJournal of Atmospheric and Solar-Terrestrial Physics
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RNA viruses as complex adaptive systems

2004

RNA viruses have high mutation rates and so their populations exist as dynamic and complex mutant distributions. It has been consistently observed that when challenged with a new environment, viral populations adapt following hyperbolic-like kinetics: adaptation is initially very rapid, but then slows down as fitness reaches an asymptotic value. These adaptive dynamics have been explained in terms of populations moving towards the top of peaks on rugged fitness landscapes. Fitness fluctuations of varying magnitude are observed during adaptation. Often the presence of fluctuations in the evolution of physical systems indicates some form of self-organization, or where many components of the s…

Statistics and ProbabilityMutation rateTime FactorsFitness landscapePhysical systemSystems TheoryProbability density functionBiologyVesicular stomatitis Indiana virusGeneral Biochemistry Genetics and Molecular BiologyEvolution MolecularRNA VirusesWeibull distributionGeneticsExperimental evolutionModels StatisticalModels GeneticComputersSystems BiologyApplied MathematicsGeneral MedicineBiological EvolutionSelf-organized criticalityEvolutionary biologyModeling and SimulationMutationAdaptationBiosystems
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