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1. Angela Shiflet, Ph. D.
Wofford College
Robert Panoff, Ph. D.
The Shodor Education Foundation
Supercomputing 2007
November 12, 2007 Mathematics Workshop
2. Modeling To analyze complex, real-world problems in order to predict what might happen
Examples
Behavior of disease in patient
HIV
Spread of disease
Flu
Ecological studies
3. Mathematica in Calculus Notebooks
Interactive lectures
Sec. 2.1 - Instantaneous velocity
Sec. 5.1 - How to measure distance traveled
www.wofford.edu/ecs/
Link to text
Link to Files to Download
http://www.shodor.org/talks/ncsi/vensim/
http://www.shodor.org/talks/ncsi/excel/
4. Systems dynamics modeling Change with time
Rate of change
Rate proportional to amount
Unconstrained growth and decay
Population growth with no constraints
5. Example: Squirrels assuming No predators
Unlimited resources
6. Example: Population of squirrels if no predators & unlimited resources s - number of squirrels in the area
t - time
Rate of change of number of squirrels (ds/dt) proportional to number of squirrels (s)
7. Vensim® To model dynamic systems
8. Vensim model of unconstrained population growth with births and deaths
9. Graph for unconstrained growth
10. Table
11. Modeling interactions Competition
Predator-Prey
Disease
12. Predator-Prey Example
13. Lotka-Volterra Model Alfred Lotka and Vito Volterra
Mathematicians
Proposed independently
1920s
Simplifying assumptions
Predator hunts only 1 prey
No other animal eats prey
14. If squirrels and hawks together Number of contacts between predators and prey proportional to s?h
15. Model of squirrel population Squirrel population helped or hurt by contact?
Deaths affected
16. Model of hawk population Hawk population helped or hurt by contact?
Births affected
17. Parameters Initial squirrel population = 100
Initial hawk population = 15
squirrel birth fraction = 2
squirrel death fraction = 0.02
hawk birth fraction = 0.01
hawk death fraction = 1.06
18. Vensim model
19. Typical graphs of numbers of prey (red) and predators (blue)
20. Interaction for spread of disease Spread of flu in boarding school
How model?
http://www.shodor.org/talks/ncsi/vensim/
http://www.shodor.org/talks/ncsi/excel/
www.wofford.edu/ecs/
Link to text
Link to Files