1,325 research outputs found
A review of wildland fire spread modelling, 1990-present 3: Mathematical analogues and simulation models
In recent years, advances in computational power and spatial data analysis
(GIS, remote sensing, etc) have led to an increase in attempts to model the
spread and behvaiour of wildland fires across the landscape. This series of
review papers endeavours to critically and comprehensively review all types of
surface fire spread models developed since 1990. This paper reviews models of a
simulation or mathematical analogue nature. Most simulation models are
implementations of existing empirical or quasi-empirical models and their
primary function is to convert these generally one dimensional models to two
dimensions and then propagate a fire perimeter across a modelled landscape.
Mathematical analogue models are those that are based on some mathematical
conceit (rather than a physical representation of fire spread) that
coincidentally simulates the spread of fire. Other papers in the series review
models of an physical or quasi-physical nature and empirical or quasi-empirical
nature. Many models are extensions or refinements of models developed before
1990. Where this is the case, these models are also discussed but much less
comprehensively.Comment: 20 pages + 9 pages references + 1 page figures. Submitted to the
International Journal of Wildland Fir
A Carbon-Cycle Based Stochastic Cellular Automata Climate Model
In this article a stochastic cellular automata model is examined, which has
been developed to study a "small" world, where local changes may noticeably
alter global characteristics. This is applied to a climate model, where global
temperature is determined by an interplay between atmospheric carbon dioxide
and carbon stored by plant life. The latter can be relased by forest fires,
giving rise to significant changes of global conditions within short time.Comment: 17 pages, 8 figure
Phase Transition in a Stochastic Forest Fire Model and Effects of the Definition of Neighbourhood
We present results on a stochastic forest fire model, where the influence of
the neighbour trees is treated in a more realistic way than usual and the
definition of neighbourhood can be tuned by an additional parameter.
This model exhibits a surprisingly sharp phase transition which can be
shifted by redefinition of neighbourhood. The results can also be interpreted
in terms of disease-spreading and are quite unsettling from the epidemologist's
point of view, since variation of one crucial parameter only by a few percent
can result in the change from endemic to epidemic behaviour.Comment: 23 pages, 13 figure
Complex network statistics to the design of fire breaks for the control of fire spreading
A computational approach for identifying efficient fuel breaks partitions for the containment of fire incidents in forests is proposed. The approach is based on the complex networks statistics, namely the centrality measures and cellular automata modeling. The efficiency of various centrality statistics, such as betweenness, closeness, Bonacich and eigenvalue centrality to select fuel breaks partitions vs. the random-based distribution is demonstrated. Two examples of increasing complexity are considered: (a) an artificial forest of randomly distributed density of vegetation, and (b) a patch from the area of Vesuvio, National Park of Campania, Italy. Both cases assume flat terrain and single type of vegetation. Simulation results over an ensemble of lattice realizations and runs show that the proposed approach appears very promising as it produces statistically significant better outcomes when compared to the random distribution approach
Modelling forest fires using complex networks
Forest fires have been a major threat to the environment throughout history. In order to mitigate its consequences, we present, in a first of a series of works, a mathematical model with the purpose of predicting fire spreading in a given land portion divided into patches, considering the area and the rate of spread of each patch as inputs. The rate of spread can be estimated from previous knowledge on fuel availability, weather and terrain conditions. We compute the time duration of the spreading process in a land patch in order to construct and parametrize a landscape network, using cellular automata simulations. We use the multilayer network model to propose a network of networks at the landscape scale, where the nodes are the local patches, each with their own spreading dynamics. We compute some respective network measures and aim, in further work, for the establishment of a fire-break structure according to increasing accuracy simulation results.info:eu-repo/semantics/publishedVersio
Reducing wildland fire hazard exploiting complex network theory. A case study analysis
We discuss a new systematic methodology to mitigate wildland fire hazard by appropriately distributing fuel breaks in space. In particular, motivated by the concept of information flow in complex networks we create a hierarchical allocation of the landscape patches that facilitate the fire propagation based on the Bonacich centrality. Reducing the fuel load in these critical patches results to lower levels of fire hazard. For illustration purposes we apply the proposed strategy to a real case of wildland fire. In particular we focus on the wildland fire that occurred in Spetses Island, Greece in 1990 and burned the one third of the forest. The efficiency of the proposed strategy is compared against the benchmark of random distribution of fuel breaks for a wide range of fuel breaks densities
The Tongue as an Excitable Medium
Geographic tongue (GT) is a benign condition affecting approximately 2% of
the population, whereby the papillae covering the upper part of the tongue are
lost due to a slowly expanding inflammation. The resultant dynamical appearance
of the tongue has striking similarities with well known phenomena observed in
excitable media, such as forest fires, cardiac dynamics and chemically-driven
reaction-diffusion systems. Here we explore the dynamics associated with GT
from a dynamical systems perspective, utilizing cellular automata simulations.
We emphasize similarities with other excitable systems as well as unique
features observed in GT. Our results shed light on the evolution of the
inflammation and contribute to the classification of the severity of the
condition, based on the characteristic patterns observed in GT patients
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