Date: Mon, 28 Mar 2011 13:33:12 -0500 (CDT) From: Mark Jacobson To: 810-025-01-spring@uni.edu Subject: Quiz on Monday, April 4th - Vensim due on Wednesday 03/30 Hello 025 students, 1. Assignment due on Wednesday. http://www.cs.uni.edu/~jacobson/025/spr11/weeksOneTwo.html 2. Quiz two on Monday, April 4th. 3. Today's class: Handouts on the Model Building process and how it connects to programming and problem solving. (3 pages on 2 sheets of paper). Ghostbusters movie parallels. I will scan in today's hand-written lecture notes so you can see them at the class web site. 4. What else did we cover in class today? NetLogo Fire model. How does it work? How can it be modified? neighbors versus neighbors4 8 neighbors versus 4 neighbors 4 neighbors for each turtle or patch: N, E, S, and W 1 2 3 4 8 neighbors for each turtle or patch: N, NE, E, SE, S, SW, W, NW 1 2 3 4 5 6 7 8 embers versus fire breed of turtles... What if the fire could spread in eight directions (including diagonals)? To do that, use "neighbors" instead of "neighbors4". How would that change the fire's chances of reaching the right edge? In this model, what "critical density" of trees is needed for the fire to propagate? ------------------------------------------------------------------------- Green patches for trees; turtles for fire, turtles for embers; ------------------------------------------------------------------------- Unburned trees are represented by green patches; burning trees are represented by turtles. Two breeds of turtles are used, "fires" and "embers". When a tree catches fire, a new fire turtle is created; a fire turns into an ember on the next turn. Notice how the program gradually darkens the color of embers to achieve the visual effect of burning out. ------------------------------------------------------------------------- How would you do the following? Add wind to the model so that the fire can "jump" greater distances in certain directions. Since the turtles are the FIRE, you can have the turtle agents look only in the direction that the wind is blowing by using IN-CONE. The IN-CONE distance angle is a CONE OF VISION. ------- -------- ----- In the following example the vision distance is 3 (the radius) and the viewing angle is 60 degrees. If the angle was 120 degrees, we would have a turtle with better and wider peripheral vision. If the distance was 6 instead of 3, the turtle could "SEE" twice as far ahead. ask turtles [ ask patches in-cone 3 60 [ set pcolor red ] ] ;; each turtle makes a red "splotch" of patches in a 60 degree ;; cone of radius 3 ahead of itself