Transcript Social studies: traffic Day 10 COLQ 201 Multiagent modeling Harry Howard Tulane University Course organization  http://www.tulane.edu/~howard/Multiagent/ 3-Feb-2010 COLQ 201, Prof.

Social studies: traffic
Day 10
COLQ 201
Multiagent modeling
Harry Howard
Tulane University
Course organization
 http://www.tulane.edu/~howard/Multiagent/
3-Feb-2010
COLQ 201, Prof. Howard, Tulane University
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Q1
 MIN = 8.0
 AVG = 9.7
 MAX = 10.0
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Explanation
 Don't just list observations.
 Don't offer a dormitive principle as an
explanation.
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Q2
 MIN = 8.0
 AVG = 9.5
 MAX = 10.0
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Traffic Basic
Models Library > Social Science
Overview
 What are the rules?
A car slows down (decelerates) if it sees a car
close ahead.
A car speeds up (accelerates) if it doesn't see a
car ahead.
 What are the parameters?
Acceleration
Deceleration
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Overview, cont.
 What are the measures?
Red car speed
The speed of a single car (turtle 0), painted red so it
can be watched.
Minimum speed
The slowest speed of any car.
Maximum speed
The fastest speed of any car (this doesn't exceed the
speed limit!)
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Think about the topic
 With a friend …
How would you define a traffic jam?
How do you think a traffic jam forms?
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First experiment
 Leave everything at the default values and
decrease the number of cars to 10.
 Run the simulation. (You may want to slow
it down.) Is there a traffic jam?
 Now gradually increase the number of cars.
 When is there the first traffic jam?
17, though it can resove itself.
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Concepts
 Are traffic jams an emergent phenomenon?
 Notice that the number of cars has a threshold or
critical value, beyond which the quality of system
changes dramatically.
 That is, a change in quantity produces a change in
quality.
 This is practically the definition of a non-linear
system.
 Sometimes this change in quality is called a phase
transition.
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Second experiment
 Return the number of cars to 20.
 Try to find the parameter settings that
optimize traffic flow.
Deceleration = 0, produces a constant speed,
but with crashes.
Decreasing one & increasing the other can
erase the traffic jam.
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Traffic Grid
Models Library > Social Science
Look at it
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Programming NetLogo
Starting form scratch
 http://ccl.northwestern.edu/netlogo/docs/
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Procedures
Models Library > Earth Science > Fire
 What is the layout of a procedure?
 What does ;; mean?
 What does ask do?
 What does if do?
 What does set do?
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Next time
 Biology: individual vs. collective movement
Independence vs. mimetism
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