Heatbugs

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WHAT IS IT? ----------- Heatbugs demonstrates how simple rules defining the behavior of agents can produce several different kinds of emergent behavior. It has been used as a demonstration model for many agent-based modeling toolkits. HOW IT WORKS ------------ The bugs move around on a grid of square "patches". A bug may not move to a patch that already has another bug on it. Each bug radiates a small amount of heat. Heat gradually diffuses through the world; some heat is lost to cooling. Each bug has an "ideal" temperature it wants to be. The bigger the difference between the temperature of the patch where the bug is and the bug's ideal temperature, the more "unhappy" the bug is. When a bug is unhappy, it moves. If it is too hot, it moves to the coolest adjacent empty patch. Conversely, if a bug is too cold, it moves to the warmest adjacent empty patch. (Note that these bugs aren't smart enough to always move to the best available patch.) HOW TO USE IT ------------- After choosing the number of bugs to create, and setting the model variables, press the GO button to set the heatbugs into motion. BUG-COUNT: The number of bugs that will inhabit the model EVAPORATION-RATE: The percentage of the world's heat that evaporates each cycle. A lower number means a world which cools slowly, a higher number is a world which cools quickly. DIFFUSION-RATE: How much heat a patch (a spot in the world) diffuses to it's neighbors. A higher number means that heat diffuses thru the world quickly. A lower number means that patches retain more of their heat. MIN/MAX-IDEAL-TEMP: The minimum and maximum ideal temperatures for heatbugs. Each bug is given an ideal temperature between the min and max ideal temperature. MIN/MAX-OUTPUT-HEAT: The minimum and maximum heat that heatbugs generate each cycle. Each bug is given a output-heat value between the min and max output heat. RANDOM-MOVE-CHANCE: The chance that a bug will make a random move even if it would prefer to stay where it is (because no more ideal patch is available). DEEP-FREEZE: This button removes all heat from the world. HEAT-UP: This button adds MAX-OUTPUT-HEAT to every patch in the world. THINGS TO NOTICE ---------------- Depending on their ideal temperatures, some bugs will tend to clump together, while others will tend to avoid all other bugs, and others still flutter around the edges of clumps. All of these behaviors are affected as well by the evaporation rate. The diffusion rate affects the cohesiveness of clumps. If diffusion-rate is slow, many tiny clumps form. Why? Most interesting behaviors occur when the number of bugs, how much heat they generate, and how quickly the world cools are balanced such that excessive heat does not build up. THINGS TO TRY ------------- Vary DIFFUSION-RATE. Vary EVAPORATION-RATE in relation to the output-heat range of the bugs. Use the HEAT-UP button to scramble clumped heatbugs and watch as they re-assemble into new clumps. EXTENDING THE MODEL ------------------- Randomize the amount of heat bugs generate each cycle. Color the bugs differently according to their ideal temperatures. Allow users to introduce heat into the system with the mouse. NETLOGO FEATURES ---------------- The DIFFUSE command is central to this model. RELATED MODELS -------------- Slime CREDITS AND REFERENCES ---------------------- Swarm version of Heatbugs -- http://www.swarm.org/examples-heatbugs.html RePast version of Heatbugs -- http://repast.sourceforge.net/examples/index.html To refer to this model in academic publications, please use: Wilensky, U. (2004). NetLogo Heatbugs model. http://ccl.northwestern.edu/netlogo/models/Heatbugs. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL. In other publications, please use: Copyright 2004 Uri Wilensky. All rights reserved. See http://ccl.northwestern.edu/netlogo/models/Heatbugs for terms of use.