Search results for "Cellular Automaton"
showing 7 items of 77 documents
Topological properties of cellular automata on trees
2012
We prove that there do not exist positively expansive cellular automata defined on the full k-ary tree shift (for k>=2). Moreover, we investigate some topological properties of these automata and their relationships, namely permutivity, surjectivity, preinjectivity, right-closingness and openness.
Probability and algorithmics: a focus on some recent developments
2017
Jean-François Coeurjolly, Adeline Leclercq-Samson Eds.; International audience; This article presents different recent theoretical results illustrating the interactions between probability and algorithmics. These contributions deal with various topics: cellular automata and calculability, variable length Markov chains and persistent random walks, perfect sampling via coupling from the past. All of them involve discrete dynamics on complex random structures.; Cet article présente différents résultats récents de nature théorique illustrant les interactions entre probabilités et algorithmique. Ces contributions traitent de sujets variés : automates cellulaires et calculabilité, chaînes de Mark…
Morphological similarities between DBM and an economic geography model of city growth
2009
International audience; An urban microeconomic model of households evolving in a 2Dcellular automata allows to simulate the growth of a metropolitan area whereland is devoted to housing, road network and agricultural/green areas. Thissystem is self-organised: based on individualistic decisions of economic agentswho compete on the land market, the model generates a metropolitan area withhouses, roads, and agriculture. Several simulation are performed. The resultsshow strong similarities with physical Dieletric breackdown models (DBM). Inparticular, phase transitions in the urban morphology occur when a controlparameter reaches critical values. Population density in our model and theelectric …
Recurrence time distribution and temporal clustering properties of a cellular automaton modelling landslide events
2018
Abstract. Reasonable prediction of landslide occurrences in a given area requires the choice of an appropriate probability distribution of recurrence time intervals. Although landslides are widespread and frequent in many parts of the world, complete databases of landslide occurrences over large periods are missing and often such natural disasters are treated as processes uncorrelated in time and, therefore, Poisson distributed. In this paper, we examine the recurrence time statistics of landslide events simulated by a cellular automaton model that reproduces well the actual frequency-size statistics of landslide catalogues. The complex time series are analysed by varying both the threshold…
Neuro-radiosurgery treatments: MRI brain tumor seeded image segmentation based on a cellular automata model
2016
Gross Tumor Volume (GTV) segmentation on medical images is an open issue in neuro-radiosurgery. Magnetic Resonance Imaging (MRI) is the most promi-nent modality in radiation therapy for soft-tissue anatomical districts. Gamma Knife stereotactic neuro-radiosurgery is a mini-invasive technique used to deal with inaccessible or insufficiently treated tumors. During the planning phase, the GTV is usually contoured by radiation oncologists using a manual segmentation procedure on MR images. This methodology is certainly time-consuming and op-erator-dependent. Delineation result repeatability, in terms of both intra- and inter-operator reliability, is only obtained by using computer-assisted appr…
Simplified Electrophysiology Modeling Framework to Assess Ventricular Arrhythmia Risk in Infarcted Patients
2021
Patients that have suffered a myocardial infarction are at lifetime high risk for sudden cardiac death (SCD). Personalized 3D computational modeling and simulation can help to find non-invasively arrhythmogenic features of patients’ infarcts, and to provide additional information for stratification and planning of radiofrequency ablation (RFA). Currently, multiscale biophysical models require high computational resources and long simulations times, which make them impractical for clinical environments. In this paper, we develop a phenomenological solver based on cellular automata to simulate cardiac electrophysiology, with results comparable to those of biophysical models. The solver can ru…
Einstein Versus Neutrinos
2013
This article focuses on the news coverage given to the CERN (European Organization for Nuclear Research) announcement that neutrinos might exceed the speed of light, flying in the face of Albert Einstein’s theory. By studying 140 cartoons about the news item published between the CERN’s announcement at the end of September 2011 up until its refutation in February 2012, we selected 33 devoted to Albert Einstein. We study the iconographic use of Einstein’s figure, and how the suggestion he might have been wrong stirred up greater interest among the cartoonists than when it was proven his ideas are still fully in force.