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Building and Template

Please note

The simulation needs a Java-Plugin (1.3.x) installed for your internet browser. If you do not already have one installed, the browser will prompt you to download the Plugin from “Sun”, who is the inventor of Java. Please download the JRE (=Java runtime environment) into a directory on your computer (e.g. “c:\temp”), execute the downloaded file for installation on your system (double-click on the file). Afterwards you will be able to reload the simulation page. Maybe you will have to restart your browser to succeed.

Run the simulation

Please click here.

Description of the simulation

The simulation is based on the simulation “building performed by termites”.

We added an environmental template to the simulation. In a termite nest, the queen resides in a special chamber. The workers construct this chamber by erecting walls in a certain distance around the queen. As the queen grows by time, they adapt the chamber permanently, so that it always perfectly fits to the queen.

A similar behavior can be found in several ant species, which place a wall of grains around their broodnest.

 

These processes are assumed to be self-organizational but influenced by an environmental template. The termite queen and the brood of ants produce pheromones that spread through the surrounding air. This is a diffusion-like process. It establishes a gradient of pheromones around the queen (or the brood nest) that provides additional cues for the workers whether they should erect piles or not. Only within a certain range of pheromone concentrations the workers erect piles that later build walls. A plot showing such locally different building probabilities is shown here:

All pictures taken from: Bonabeau E., Dorigo M. and Theraulaz G. (1999) Swarm intelligence. From natural to artificial systems. Santa Fee Institute studies in the sciences of complexity. Oxford University Press

Parameters

The slider density-of-chips sets the density of chips distributed randomly at the beginning

The slider number sets the number of termites that are used in the simulation

The sliders Puturn and turn-angle set the basic parameters of the random walk. Please note that the ants always perform simply a random walk.

The slider queen-growth-rate determines the growing speed of the queen

The sliders evaporation-rate and diffusion-rate determine the physics of the queen pheromone in our simulation.

Experiments

  • Check how the number of actors and of the chip density affect the sorting speed and result.
  • Check how the growing rate of the queen and the pheromone physics have to be adequate to ensure proper building of the queen chamber.

Screenshots

The following series of images shows how the wall building evolves:

Implementation

The presented NetLogo simulation was written by:
Thomas Schmickl (2002), Department for Zoology, Karl-Franzens-University Graz, Austria, Europe,
schmickl@nextra.at, thomas.schmickl@uni-graz.at

Further readings

  • Camazine S., Deneubourg J.-L., Franks N.R., Sneyd J., Theraulaz G. and Bonabeau E. (2001) Self-Organization in biological systems. Princeton University Press
  • Resnick M. (2000) Turtles, termites and traffic jams. MIT Press.
  • Bonabeau E., Dorigo M. and Theraulaz G. (1999) Swarm intelligence. From natural to artificial systems. Santa Fee Institute studies in the sciences of complexity. Oxford University Press

 

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