globals [ acceleration ; due to gravity bricks-per-floor ; controls the density of the display freefall-height ; height of crash point during freefall freefall-ycor ; y-coord of crash point during freefall freefall-times ; times at which regular spatial steps reached by freefall Freefall-Time ; finally reported fall time of the free falling building freefalltime ; total fall time for the free falling building collapse-height ; height of crash point during collapse collapse-ycor ; y-coord of crash point during collapse collapse-times ; times at which regular spatial steps reached by collapse Collapse-Time ; finally reported fall time of the collapsing building collapsetime ; total fall time for the collapsing building crash-height ; height (m) of crash floor = crash-floor * floor-height building-height ; height (m) of building = number-of-floors * floor-height number-of-spatial-steps ; total fall distance divided into number-of-spatial-steps number-of-temporal-steps ; total fall time divided into number-of-temporal-steps spatial-increment ; separation between spatial steps temporal-increment ; separation between temporal steps time ; current time from fall begin max-time ; time required for freefall from building-height number-of-plot-points ; refinement factor for display cloud-parity ; controls whether dust appears right or left of building floor-rupturing-momentum ; critical momentum required to rupture a floor new-fraction-to-dust ; dust fraction adjusted by supplemental-mass-pulverization ] breed [freefall-bricks freefall-brick] ; bricks in the free-falling building breed [collapse-bricks collapse-brick] ; bricks in the collapsing building breed [collapse-clouds collapse-cloud] ; bricks of collapsing building turned to dust breed [airplanes airplane] ; airplanes appearing during setup freefall-bricks-own [falling] ; falling = 0 (no), 1 (yes), -1 (above crash) collapse-bricks-own [falling] to setup clear-all ; begin fresh setup-parameters ; pre-compute global parameters setup-patches ; set the background setup-bricks ; build the buildings crash-airplanes ; shows the crash height compute-times ; freefall-times and collapse-times are precomputed end to start if (((max [ycor] of freefall-bricks) <= 0) and ; stop if y-coord's <= 0 ((max [ycor] of collapse-bricks) <= 0)) [stop] move-freefall-bricks ; take a freefall step move-collapse-bricks ; take a collapse step do-plots ; plot the trajectories set time (time + temporal-increment) ; increment the time end to setup-parameters if (crash-floor > number-of-floors) [set crash-floor number-of-floors] ; in case user does otherwise set acceleration 9.81 ; g = 9.81 m/s^2 set bricks-per-floor int (max-pxcor / 5) ; one brick per column in 50-column field set building-height (floor-height * number-of-floors) ; typical floor height is 3.79 m, set by user set crash-height (floor-height * crash-floor) ; user sets crash-floor and number-of-floors set number-of-plot-points 2 ; higher means slower set number-of-spatial-steps (number-of-floors * number-of-plot-points) ; at least one step over entire building height set time 0 ; start time at zero set Freefall-Time 0 ; initialize Freefall-Time set Collapse-Time 0 ; initialize Collapse-Time set freefall-height crash-height ; initialize freefall-height set collapse-height crash-height ; initialize collapse-height set spatial-increment (building-height / number-of-spatial-steps) ; regular spatial step set max-time sqrt ((building-height * 2) / acceleration) ; time required for freefall from building-height set number-of-temporal-steps number-of-spatial-steps ; same number of temporal and spatial steps set temporal-increment (max-time / number-of-temporal-steps) ; regular temporal step set freefall-ycor crash-floor ; initialize freefall y-coord set collapse-ycor crash-floor ; initialize collapse y-coord set cloud-parity 1 ; start dust on the right set new-fraction-to-dust (1 - (1 - mass-fraction-turned-to-dust) * (1 - (supplemental-mass-pulverization / 100))) ; between 0 and 1 depending upon user set floor-rupturing-momentum (floors-needed-to-break-next-floor * sqrt ((2 * acceleration) * floor-height)) ; mass of falling floors (measured in numbers of floors) set floor-rupturing-momentum (floor-rupturing-momentum * (1 - (supplemental-floor-weakening / 100))) ; X velocity of floors falling one floor-height end to setup-patches ask patches [ set pcolor cyan ] ; set cyan sky end to setup-bricks setup-collapse-bricks ; build the collapsing building first setup-freefall-bricks ; build the free-falling building second end to setup-collapse-bricks create-collapse-bricks (number-of-floors * bricks-per-floor) ; create all the collapse bricks foreach ( n-values number-of-floors [?] ) ; situate one floor at a time [ let current-floor (? + 1) ask collapse-bricks with [(who >= ((current-floor - 1) * bricks-per-floor)) and (who < (current-floor * bricks-per-floor))] [ set xcor ((((who mod bricks-per-floor) / bricks-per-floor) + 1) * (max-pxcor / 5)) set ycor current-floor ; column is xcor and row is ycor set color black set shape "link direction" ; closest shape in library set heading 0 ; shape points upward set falling 0 ; not falling ] ] ask collapse-bricks with [ycor >= crash-floor] [set falling (-1)] ; label bricks above crash point end to setup-freefall-bricks create-freefall-bricks (number-of-floors * bricks-per-floor) ; create all the freefall bricks foreach ( n-values number-of-floors [?] ) ; situate one floor at a time [ let current-floor (? + 1) ask freefall-bricks with [(who >= (((number-of-floors + current-floor) - 1) * bricks-per-floor)) and (who < ((number-of-floors + current-floor) * bricks-per-floor))] [ set xcor ((((who mod bricks-per-floor) / bricks-per-floor) + 3) * (max-pxcor / 5)) set ycor current-floor ; column is xcor and row is ycor set color black set shape "link direction" ; closest shape in library set heading 0 ; shape points upward set falling 0 ; not falling ] ] ask freefall-bricks with [ycor >= crash-floor] [set falling (-1)] ; label bricks above crash point end to crash-airplanes create-airplanes 2 ; create two airplanes ask airplanes [ set color red set ycor crash-floor ; situate at crash-floor height set shape "airplane" ; in the library set size 2 ; large enough ] ask min-one-of airplanes [who] [ set xcor 0 ; one airplane on the left set heading 90 ; heading to the right ] ask max-one-of airplanes [who] [ ; other airplane on the right set xcor (max-pxcor * (((5 * bricks-per-floor) - 1) / (5 * bricks-per-floor))) set heading 270 ; heading to the left ] ask airplanes [ repeat ((max-pxcor / 5) - 1) [forward 1 wait 0.1] ; move airplanes toward buildings forward 1 set shape "star" ; at collision transform to star wait 1 ] ask airplanes [ ask turtles with [ycor = crash-floor] [ set color red ; turn all crashed bricks to red ] die ; remove the airplanes ] end to compute-times compute-freefall-times ; pre-compute the freefall times compute-collapse-times ; pre-compute the collapse times end ; for k=0,number-of-spatial-steps, dx=spatial-increment, and tk=freefall-times(k), to compute-freefall-times ; k*dx = (g/2)*tk^2, where at the last time, the top floor hits the ground set freefall-times (n-values (number-of-spatial-steps + 1) [sqrt (((2 * (spatial-increment * ?)) / acceleration))] ) set freefalltime (last freefall-times) end to compute-collapse-times let mcoll ((number-of-floors - crash-floor) + 1) ; mass of load above crash point, measured in numbers of floors let vcoll 0 ; initial velocity of this load let mfall mcoll ; mass after falling one floor-height let vfall (0 - sqrt ((vcoll ^ 2) + ((2 * acceleration) * floor-height))) ; velocity after falling one floor-height set collapse-times (list) ; initialize collapse-times to an empty list let ttmp (list) ; initialize times between collisions to an empty list let told 0 ; told and tnew are times between consecutive collisions, and let tnew told ; they are initialized to the initial time. let remaining-mass 0 ; remaining mass after pulverization let npts number-of-plot-points ; shorthand for number of time points between collisions foreach ( n-values (crash-floor - 1) [?] ) ; loop only over the floors up to crash floor [ if (vcoll <= 0) ; continue only if the velocity remains downward after collisions [ ; told and tnew are times of consecutive collisions separated by freefall set tnew (told + ((vcoll + sqrt ((vcoll ^ 2) + ((2 * acceleration) * floor-height))) / acceleration)) set ttmp (n-values npts [told + ((vcoll + sqrt ((vcoll ^ 2) + ((2 * acceleration) * (spatial-increment * ?)))) / acceleration)]) ; for k=0,npts-1, dx=spatial-increment, & tk=ttmp(k), ; tk = told + (vcoll + sqrt(vcoll^2 + 2*g*dx*k))/g set collapse-times (sentence collapse-times ttmp) ; extend the list of collapse times set remaining-mass (1 - new-fraction-to-dust) ; the remaining mass in the next floor plus the falling mass mfall is set mcoll (remaining-mass + mfall) ; the mass after the collision of the two. The old momentum mfall*vfall<0 is added to resisiting momentum set vcoll ((floor-rupturing-momentum + (mfall * vfall)) / mcoll) ; floor-rupturing-momentum to give the new momentum mcoll*vcoll<0. set mfall mcoll ; update to the next freefall interval set vfall (0 - sqrt ((vcoll ^ 2) + ((2 * acceleration) * floor-height))) set told tnew ] ] if (vcoll <= 0) [ ; for the remaining floors above the crash point implement a freefall at the end let remaining-height (((number-of-floors - crash-floor) + 1) * floor-height) ; height of remaining floors set tnew (told + ((vcoll + sqrt ((vcoll ^ 2) + ((2 * acceleration) * remaining-height))) / acceleration)) ; time required for the freefall set npts (remaining-height / spatial-increment) + 1 ; number of remaining points using the usual increment set ttmp (n-values npts [told + ((vcoll + sqrt ((vcoll ^ 2) + ((2 * acceleration) * (spatial-increment * ?)))) / acceleration)]) ; for k=0,npts-1, dx=spatial-increment, & tk=ttmp(k), set collapse-times (sentence collapse-times ttmp) ; tk = told + (vcoll + sqrt(vcoll^2 + 2*g*dx*k))/g set told tnew ] set collapsetime told end to move-freefall-bricks let k (length (filter [? <= time] freefall-times) - 1) ; number of freefall-times up to time set freefall-height (crash-height - (k * spatial-increment)) ; reduce the height of the free-falling crash point let fall-height ((freefall-ycor * floor-height) - freefall-height) ; how far has the free-falling crash point just fallen set freefall-ycor max list (freefall-ycor - (fall-height / floor-height)) (freefall-height / floor-height) ; y-coord of the free-falling crash point ask freefall-bricks with [((ycor * floor-height) > freefall-height) and (falling = 0)] ; display the new falling bricks with emphasis [ set falling 1 ; these bricks are now falling set size 3 ; they are now larger set color white ; and white ] ask freefall-bricks with [(ycor * floor-height) > freefall-height] ; let the bricks still above freefall-height drop down [ set ycor max (list max (list (ycor - (fall-height / floor-height)) (freefall-height / floor-height)) 0) ] ask freefall-bricks with [ycor <= 0] [ ; flatten the bricks on the ground set shape "link" set heading 90 ] end to move-collapse-bricks let k (length (filter [? <= time] collapse-times) - 1) ; number of collapse-times up to time set collapse-height (crash-height - (k * spatial-increment)) ; reduce the height of the collapsing crash point let fall-height ((collapse-ycor * floor-height) - collapse-height) ; how far has the collapsing crash point just fallen set collapse-ycor max list (collapse-ycor - (fall-height / floor-height)) (collapse-height / floor-height) ; y-coord of the collapsing crash point let next-collapse-bricks collapse-bricks with [((ycor * floor-height) > collapse-height) and (falling = 0)] ; find the new collapsing bricks let number-of-next-collapse-bricks count next-collapse-bricks if (number-of-next-collapse-bricks > 0) [ foreach ( n-values (new-fraction-to-dust * number-of-next-collapse-bricks) [?] ) ; pulverize a fraction of the new collapsing bricks [ ask one-of next-collapse-bricks [ set cloud-parity (0 - cloud-parity) ; alternate the current cloud parity set xcor (random (max-pxcor / 5)) ; by default move the brick to the left of the building if (cloud-parity > 0) [set xcor (((max-pxcor / 5) * 2) + (random (max-pxcor / 5)))] ; or else move it to the right let sav-xcor xcor hatch-collapse-clouds 1 ; hatch a dust cloud at [ set xcor sav-xcor ; the same coordinates of the brick set shape "circle" ; give it a round shape and set color white ; a white color and set size 1 ; moderate size, and finally ] die ; remove the brick ] ] ] ask next-collapse-bricks ; for the remaining new collapsing bricks [ set falling 1 ; these bricks are now falling set size 3 ; they are now larger set color white ; and white ] ask collapse-bricks with [(ycor * floor-height) > collapse-height] ; let the bricks still above freefall-height drop down [ set ycor max (list max (list (ycor - (fall-height / floor-height)) (collapse-height / floor-height)) 0) ] ask collapse-bricks with [ycor <= 0] [ ; flatten the bricks on the ground set shape "link" set heading 90 ] end to do-plots ; plot the trajectories together set-current-plot "Fall Trajectories" set-current-plot-pen "Freefall-Height" let tmp1 ((max [ycor] of freefall-bricks * floor-height)) ; set the Freefall-Time if ((tmp1 <= 0) and (Freefall-Time = 0)) [set Freefall-Time freefalltime] plotxy time tmp1 set-current-plot-pen "Collapse-Height" let tmp2 ((max [ycor] of collapse-bricks * floor-height)) ; set the Collapse-Time if ((tmp2 <= 0) and (Collapse-Time = 0)) [set Collapse-Time collapsetime] plotxy time tmp2 end @#$#@#$#@ GRAPHICS-WINDOW 346 15 611 651 -1 -1 5.0 1 10 1 1 1 0 1 1 1 0 50 0 120 0 0 1 ticks CC-WINDOW 5 665 620 760 Command Center 0 SLIDER 35 70 333 103 number-of-floors number-of-floors 1 120 110 1 1 NIL HORIZONTAL BUTTON 35 13 98 46 NIL setup NIL 1 T OBSERVER NIL NIL NIL NIL BUTTON 268 15 331 48 NIL start T 1 T OBSERVER NIL NIL NIL NIL SLIDER 36 108 334 141 crash-floor crash-floor 0 120 100 1 1 NIL HORIZONTAL SLIDER 35 144 333 177 floor-height floor-height 1 4 3.79 0.01 1 m HORIZONTAL PLOT 39 422 334 648 Fall Trajectories Time (s) Height (m) 0.0 10.0 0.0 10.0 true true PENS "Freefall-Height" 1.0 0 -11221820 true "Collapse-Height" 1.0 0 -16777216 true SLIDER 36 182 332 215 mass-fraction-turned-to-dust mass-fraction-turned-to-dust 0 1 0.5 0.1 1 NIL HORIZONTAL SLIDER 36 219 332 252 floors-needed-to-break-next-floor floors-needed-to-break-next-floor 0 10 5 1 1 NIL HORIZONTAL SLIDER 35 278 333 311 supplemental-mass-pulverization supplemental-mass-pulverization 0 100 0 1 1 % HORIZONTAL SLIDER 35 315 333 348 supplemental-floor-weakening supplemental-floor-weakening 0 100 0 1 1 % HORIZONTAL MONITOR 228 360 333 409 NIL Freefall-Time 3 1 12 MONITOR 37 360 142 409 NIL Collapse-Time 3 1 12 @#$#@#$#@ HOMEPAGE FOR WTC.NLOGO ---------------------- For basic information and links related to this code see http://math.uni-graz.at/keeling/wtc.html. For information about the simulation written for the interested user, see http://math.uni-graz.at/keeling/wtc1.html. For a detailed mathematical basis of the simulation, see the derivation at http://math.uni-graz.at/keeling/wtc2.html. @#$#@#$#@ default true 0 Polygon -7500403 true true 150 5 40 250 150 205 260 250 airplane true 0 Polygon -7500403 true true 150 0 135 15 120 60 120 105 15 165 15 195 120 180 135 240 105 270 120 285 150 270 180 285 210 270 165 240 180 180 285 195 285 165 180 105 180 60 165 15 arrow true 0 Polygon -7500403 true true 150 0 0 150 105 150 105 293 195 293 195 150 300 150 box false 0 Polygon -7500403 true true 150 285 285 225 285 75 150 135 Polygon -7500403 true true 150 135 15 75 150 15 285 75 Polygon -7500403 true true 15 75 15 225 150 285 150 135 Line -16777216 false 150 285 150 135 Line -16777216 false 150 135 15 75 Line -16777216 false 150 135 285 75 bug true 0 Circle -7500403 true true 96 182 108 Circle -7500403 true true 110 127 80 Circle -7500403 true true 110 75 80 Line -7500403 true 150 100 80 30 Line -7500403 true 150 100 220 30 butterfly true 0 Polygon -7500403 true true 150 165 209 199 225 225 225 255 195 270 165 255 150 240 Polygon -7500403 true true 150 165 89 198 75 225 75 255 105 270 135 255 150 240 Polygon -7500403 true true 139 148 100 105 55 90 25 90 10 105 10 135 25 180 40 195 85 194 139 163 Polygon -7500403 true true 162 150 200 105 245 90 275 90 290 105 290 135 275 180 260 195 215 195 162 165 Polygon -16777216 true false 150 255 135 225 120 150 135 120 150 105 165 120 180 150 165 225 Circle -16777216 true false 135 90 30 Line -16777216 false 150 105 195 60 Line -16777216 false 150 105 105 60 car false 0 Polygon -7500403 true true 300 180 279 164 261 144 240 135 226 132 213 106 203 84 185 63 159 50 135 50 75 60 0 150 0 165 0 225 300 225 300 180 Circle -16777216 true false 180 180 90 Circle -16777216 true false 30 180 90 Polygon -16777216 true false 162 80 132 78 134 135 209 135 194 105 189 96 180 89 Circle -7500403 true true 47 195 58 Circle -7500403 true true 195 195 58 circle false 0 Circle -7500403 true true 0 0 300 circle 2 false 0 Circle -7500403 true true 0 0 300 Circle -16777216 true false 30 30 240 cow false 0 Polygon -7500403 true true 200 193 197 249 179 249 177 196 166 187 140 189 93 191 78 179 72 211 49 209 48 181 37 149 25 120 25 89 45 72 103 84 179 75 198 76 252 64 272 81 293 103 285 121 255 121 242 118 224 167 Polygon -7500403 true true 73 210 86 251 62 249 48 208 Polygon -7500403 true true 25 114 16 195 9 204 23 213 25 200 39 123 cylinder false 0 Circle -7500403 true true 0 0 300 dot false 0 Circle -7500403 true true 90 90 120 face happy false 0 Circle -7500403 true true 8 8 285 Circle -16777216 true false 60 75 60 Circle -16777216 true false 180 75 60 Polygon -16777216 true false 150 255 90 239 62 213 47 191 67 179 90 203 109 218 150 225 192 218 210 203 227 181 251 194 236 217 212 240 face neutral false 0 Circle -7500403 true true 8 7 285 Circle -16777216 true false 60 75 60 Circle -16777216 true false 180 75 60 Rectangle -16777216 true false 60 195 240 225 face sad false 0 Circle -7500403 true true 8 8 285 Circle -16777216 true false 60 75 60 Circle -16777216 true false 180 75 60 Polygon -16777216 true false 150 168 90 184 62 210 47 232 67 244 90 220 109 205 150 198 192 205 210 220 227 242 251 229 236 206 212 183 fish false 0 Polygon -1 true false 44 131 21 87 15 86 0 120 15 150 0 180 13 214 20 212 45 166 Polygon -1 true false 135 195 119 235 95 218 76 210 46 204 60 165 Polygon -1 true false 75 45 83 77 71 103 86 114 166 78 135 60 Polygon -7500403 true true 30 136 151 77 226 81 280 119 292 146 292 160 287 170 270 195 195 210 151 212 30 166 Circle -16777216 true false 215 106 30 flag false 0 Rectangle -7500403 true true 60 15 75 300 Polygon -7500403 true true 90 150 270 90 90 30 Line -7500403 true 75 135 90 135 Line -7500403 true 75 45 90 45 flower false 0 Polygon -10899396 true false 135 120 165 165 180 210 180 240 150 300 165 300 195 240 195 195 165 135 Circle -7500403 true true 85 132 38 Circle -7500403 true true 130 147 38 Circle -7500403 true true 192 85 38 Circle -7500403 true true 85 40 38 Circle -7500403 true true 177 40 38 Circle -7500403 true true 177 132 38 Circle -7500403 true true 70 85 38 Circle -7500403 true true 130 25 38 Circle -7500403 true true 96 51 108 Circle -16777216 true false 113 68 74 Polygon -10899396 true false 189 233 219 188 249 173 279 188 234 218 Polygon -10899396 true false 180 255 150 210 105 210 75 240 135 240 house false 0 Rectangle -7500403 true true 45 120 255 285 Rectangle -16777216 true false 120 210 180 285 Polygon -7500403 true true 15 120 150 15 285 120 Line -16777216 false 30 120 270 120 leaf false 0 Polygon -7500403 true true 150 210 135 195 120 210 60 210 30 195 60 180 60 165 15 135 30 120 15 105 40 104 45 90 60 90 90 105 105 120 120 120 105 60 120 60 135 30 150 15 165 30 180 60 195 60 180 120 195 120 210 105 240 90 255 90 263 104 285 105 270 120 285 135 240 165 240 180 270 195 240 210 180 210 165 195 Polygon -7500403 true true 135 195 135 240 120 255 105 255 105 285 135 285 165 240 165 195 line true 0 Line -7500403 true 150 0 150 300 line half true 0 Line -7500403 true 150 0 150 150 link true 0 Line -7500403 true 150 0 150 300 link direction true 0 Line -7500403 true 150 150 30 225 Line -7500403 true 150 150 270 225 pentagon false 0 Polygon -7500403 true true 150 15 15 120 60 285 240 285 285 120 person false 0 Circle -7500403 true true 110 5 80 Polygon -7500403 true true 105 90 120 195 90 285 105 300 135 300 150 225 165 300 195 300 210 285 180 195 195 90 Rectangle -7500403 true true 127 79 172 94 Polygon -7500403 true true 195 90 240 150 225 180 165 105 Polygon -7500403 true true 105 90 60 150 75 180 135 105 plant false 0 Rectangle -7500403 true true 135 90 165 300 Polygon -7500403 true true 135 255 90 210 45 195 75 255 135 285 Polygon -7500403 true true 165 255 210 210 255 195 225 255 165 285 Polygon -7500403 true true 135 180 90 135 45 120 75 180 135 210 Polygon -7500403 true true 165 180 165 210 225 180 255 120 210 135 Polygon -7500403 true true 135 105 90 60 45 45 75 105 135 135 Polygon -7500403 true true 165 105 165 135 225 105 255 45 210 60 Polygon -7500403 true true 135 90 120 45 150 15 180 45 165 90 square false 0 Rectangle -7500403 true true 30 30 270 270 square 2 false 0 Rectangle -7500403 true true 30 30 270 270 Rectangle -16777216 true false 60 60 240 240 star false 0 Polygon -7500403 true true 151 1 185 108 298 108 207 175 242 282 151 216 59 282 94 175 3 108 116 108 target false 0 Circle -7500403 true true 0 0 300 Circle -16777216 true false 30 30 240 Circle -7500403 true true 60 60 180 Circle -16777216 true false 90 90 120 Circle -7500403 true true 120 120 60 tree false 0 Circle -7500403 true true 118 3 94 Rectangle -6459832 true false 120 195 180 300 Circle -7500403 true true 65 21 108 Circle -7500403 true true 116 41 127 Circle -7500403 true true 45 90 120 Circle -7500403 true true 104 74 152 triangle false 0 Polygon -7500403 true true 150 30 15 255 285 255 triangle 2 false 0 Polygon -7500403 true true 150 30 15 255 285 255 Polygon -16777216 true false 151 99 225 223 75 224 truck false 0 Rectangle -7500403 true true 4 45 195 187 Polygon -7500403 true true 296 193 296 150 259 134 244 104 208 104 207 194 Rectangle -1 true false 195 60 195 105 Polygon -16777216 true false 238 112 252 141 219 141 218 112 Circle -16777216 true false 234 174 42 Rectangle -7500403 true true 181 185 214 194 Circle -16777216 true false 144 174 42 Circle -16777216 true false 24 174 42 Circle -7500403 false true 24 174 42 Circle -7500403 false true 144 174 42 Circle -7500403 false true 234 174 42 turtle true 0 Polygon -10899396 true false 215 204 240 233 246 254 228 266 215 252 193 210 Polygon -10899396 true false 195 90 225 75 245 75 260 89 269 108 261 124 240 105 225 105 210 105 Polygon -10899396 true false 105 90 75 75 55 75 40 89 31 108 39 124 60 105 75 105 90 105 Polygon -10899396 true false 132 85 134 64 107 51 108 17 150 2 192 18 192 52 169 65 172 87 Polygon -10899396 true false 85 204 60 233 54 254 72 266 85 252 107 210 Polygon -7500403 true true 119 75 179 75 209 101 224 135 220 225 175 261 128 261 81 224 74 135 88 99 wheel false 0 Circle -7500403 true true 3 3 294 Circle -16777216 true false 30 30 240 Line -7500403 true 150 285 150 15 Line -7500403 true 15 150 285 150 Circle -7500403 true true 120 120 60 Line -7500403 true 216 40 79 269 Line -7500403 true 40 84 269 221 Line -7500403 true 40 216 269 79 Line -7500403 true 84 40 221 269 x false 0 Polygon -7500403 true true 270 75 225 30 30 225 75 270 Polygon -7500403 true true 30 75 75 30 270 225 225 270 @#$#@#$#@ NetLogo 4.0 @#$#@#$#@ @#$#@#$#@ @#$#@#$#@ @#$#@#$#@ @#$#@#$#@ default 0.0 -0.2 0 0.0 1.0 0.0 1 1.0 0.0 0.2 0 0.0 1.0 link direction true 0 Line -7500403 true 150 150 90 180 Line -7500403 true 150 150 210 180 @#$#@#$#@