scholarly journals Self-organized braiding in solar coronal loops

2015 ◽  
Vol 81 (4) ◽  
Author(s):  
M. A. Berger ◽  
M. Asgari-Targhi ◽  
E. E. DeLuca
Keyword(s):  
Coronal Loops ◽  
Frequency Distributions ◽  
Fire Model ◽  
X Ray ◽  
Self Organized ◽  
Forest Fire Model ◽  
Distribution Laws ◽  
Field Lines ◽  
Power Law Distributions ◽  
Solar Coronal

AbstractIn this paper, we investigate the evolution of braided solar coronal loops. We assume that coronal loops consist of several internal strands which twist and braid about each other. Reconnection between the strands leads to small flares and heating of the loop to x-ray temperatures. Using a method of generating and releasing braid structure similar to a forest fire model, we show that the reconnected field lines evolve to a self-organised critical state. In this state, the frequency distributions of coherent braid sequences as well as flare energies follow power law distributions. We demonstrate how the presence of net helicity in the loop alters the distribution laws.

Forest Fires

2017 ◽  
Author(s):  
Paul Charbonneau
Keyword(s):  
Forest Fire ◽  
Forest Fires ◽  
Model Simulation ◽  
Percolation Cluster ◽  
Natural Process ◽  
Wildfire Management ◽  
Fire Model ◽  
Self Organized ◽  
Forest Fire Model ◽  
Self Organized Criticality

This chapter explores how a “natural” process generates dynamically something that is conceptually similar to a percolation cluster by using the case of forest fires. It first provides an overview of the forest-fire model, which is essentially a probabilistic cellular automata, before discussing its numerical implementation using the Python code. It then describes a representative simulation showing the triggering, growth, and decay of a large fire in a representative forest-fire model simulation on a small 100 x 100 lattice. It also considers the behavior of the forest-fire model as well as its self-organized criticality and concludes with an analysis of the advantages and limitations of wildfire management. The chapter includes exercises and further computational explorations, along with a suggested list of materials for further reading.

Visualization of resonant absorption in solar coronal loops by simulation of soft x-ray images

1996 ◽  
Vol 10 (6) ◽  
pp. 573 ◽  
Author(s):  
A. J. C. Beliën ◽  
S. Poedts ◽  
H. J. W. Spoelder ◽  
R. Leenders ◽  
J. P. Goedbloed
Keyword(s):  
Resonant Absorption ◽  
Coronal Loops ◽  
X Ray ◽  
Solar Coronal

scholarly journals Universality in the One-Dimensional Self-Organized Critical Forest-Fire Model

1994 ◽  
Vol 49 (9) ◽  
pp. 856-860
Author(s):  
Barbara Drossel ◽  
Siegfried Clar ◽  
Franz Schwabl
Keyword(s):  
Size Distribution ◽  
Forest Fire ◽  
Nearest Neighbor ◽  
The Self ◽  
One Dimension ◽  
Fire Model ◽  
One Dimensional ◽  
Self Organized ◽  
Forest Fire Model ◽  
The One

Abstract We modify the rules of the self-organized critical forest-fire model in one dimension by allowing the fire to jum p over holes of ≤ k sites. An analytic calculation shows that not only the size distribution of forest clusters but also the size distribution of fires is characterized by the same critical exponent as in the nearest-neighbor model, i.e. the critical behavior of the model is universal. Computer simulations confirm the analytic results.

scholarly journals Exact results for the one-dimensional self-organized critical forest-fire model

1993 ◽  
Vol 71 (23) ◽  
pp. 3739-3742 ◽  
Author(s):  
Barbara Drossel ◽  
Siegfried Clar ◽  
Franz Schwabl
Keyword(s):  
Forest Fire ◽  
Exact Results ◽  
Fire Model ◽  
One Dimensional ◽  
Self Organized ◽  
Forest Fire Model ◽  
The One

SELF ORGANIZATION IN A FOREST-FIRE MODEL

Fractals ◽  
1993 ◽  
Vol 01 (04) ◽  
pp. 1022-1029 ◽  
Author(s):  
B. DROSSEL ◽  
F. SCHWABL
Keyword(s):  
Forest Fire ◽  
Critical Line ◽  
Continuous Phase ◽  
Excitable Media ◽  
Fire Model ◽  
Fire Propagation ◽  
Self Organized ◽  
Forest Fire Model ◽  
New Type ◽  
Fire Spreading

We generalize the forest-fire model of P. Bak et al., which contains a tree nearest growth probability p and fire spreading to the neighbors, by including a lightning probability f and an immunity g which is the probability that a tree catches no fire although one of its neighbors is burning. The model becomes self-organized critical in the limit f/p→0, provided the time scales of tree growth and burning down of forest clusters are separated. The size distribution of forest clusters obeys a power law. We calculate the critical exponents in one dimension. A continuous phase transition is observed in the general forest-fire model when g reaches its critical value. We determine the critical line gC(p) and show that the critical fire propagation represents a new type of percolation. Finally, we point out similarities between the forest-fire model and excitable media, which comprise such different systems as chemical reactions, spreading of diseases and populations, and propagation of electrical activity in neurons.

Fractality and Self-Organized Criticality of Wars

Fractals ◽  
1998 ◽  
Vol 06 (04) ◽  
pp. 351-357 ◽  
Author(s):  
D. C. Roberts ◽  
D. L. Turcotte
Keyword(s):  
Forest Fire ◽  
Power Law ◽  
Forest Fires ◽  
Size Dependence ◽  
Fire Model ◽  
Self Organized ◽  
Battle Deaths ◽  
Forest Fire Model ◽  
Alternative Measures ◽  
Self Organized Criticality

This paper considers the frequency-size statistics of wars. Using several alternative measures of the intensity of a war in terms of battle deaths, we find a fractal (power-law) dependence of number on intensity. We show that the frequency-size dependence of forest fires is essentially identical to that of wars. The forest-fire model provides a basis for understanding the distribution of forest firest in terms of self-organized criticality. We extend the analogy to wars in terms of the initial ignition (outbreak of war) and its spread to a group of metastable countries.

The Self-Organized Critical Forest-Fire Model with Trees and Bushes

1995 ◽  
Vol 5 (9) ◽  
pp. 1233-1238 ◽  
Author(s):  
B. Strocka ◽  
J. A.M.S. Duarte ◽  
M. Schreckenberg
Keyword(s):  
Forest Fire ◽  
The Self ◽  
Fire Model ◽  
Self Organized ◽  
Forest Fire Model
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