1. Pedro Ribeiro de Andrade Münster, 2013
Systems Theory
Pedro Ribeiro de Andrade
Münster, 2013

2. Systems Theory
Provides a unified classification for scientific knowledge.
Enunciated by biologist Ludwig Von Bertalanffy:
1920s: earliest developments
1937: Charles Morris Philosophy Seminar, University of Chicago
1950: “An Outline of General Systems Theory”, Journal for the Philosophy of Science
Scientists that introduced Systems Theory in their fields:
Parsons, sociologist (1951)
J.G Miller, psychiatrist & psychologist (1955)
Boulding, economist (1956)
Rapoport, mathematician (1956)
Ashby, bacteriologist (1958)

3. Conception of Reality Any measurable part of reality can be modeled
Systems are represented as stocks and flows
Stocks represent energy, matter, or information
Flows connect and transport stocks
Systems are opened or closed

4. A system Can you identify parts? and
Do the parts affect each other? and
Do the parts together produce an effect that is different from the effect of each part on its own? and perhaps
Does the effect, the behavior over time, persist in a variety of circumstances?
Source: (Meadows, 2008)

7. Earth as a system

8. Tools for system dynamics
Dinamo
Vensim
Simile
STELLA

9. Water in the tub Initial stock: water in tub = 40 gallons
water in tub(t) = water in tub(t – dt) – outflow x dt
t = minutes
dt = 1 minute
Runtime = 8 minutes
Outflow = 5 gal/min

10. Cell (description extracted from “TerraME types and functions”)
Not yet
(description extracted from “TerraME types and functions”)

11. Event
Not yet
Not yet

12. Temporal model . . . false true Source: (Carneiro et al., 2013)
1:32:10
ag1:execute( )
1:38:07
ag2:execute( )
1:42:00
cs:save()
. . .
(4) ACTION
return value
true
(1) Get first EVENT
1:32:00
cs:load( )
(2) Update current time
(3) Execute the ACTION
false
(5) Schedule EVENT again
Source: (Carneiro et al., 2013) 12

13. Observer
Not yet

14. Water in the tub Initial stock: water in tub = 40 gallons
water in tub(t) = water in tub(t – dt) – outflow x dt
t = minutes
dt = 1 minute
Runtime = 8 minutes
Outflow = 5 gal/min

15. Water in the tub 2 Initial stock: water in tub = 40 gallons
water in tub(t) = water in tub(t – dt) – outflow x dt
t = minutes
dt = 1 minute
Runtime = 8 minutes
Outflow = 5 gal/min
Inflow = 40 gal every 10 min

16. Conclusions Two ways to increase stocks
Stocks act as delays or buffers
Stocks allow inflows and outflows to be decoupled