Stocks and Flows
The stock and flow model is a simple but powerful model with broad relevance. Anything with inputs and outputs and an overall level is appropriate. The carbon dioxide in the atmosphere and the amount of money in a bank account are good examples.
Stocks and flows
Bath tub model
Steady state
Residence time
Future activities
Carbon dioxide concentration in ETC
California drought
Bath tub model
Flow in
Flow out
Level of water in the tub
Atmospheric CO2 Bathtub Model
Steady State
Level in bathtub is steady
Brainstorm
What things could be modeled with this
Residence time
How long does something remain in the bath tub?
Adding rates
What happens with two faucets?
Carbon dioxide Activity
Estimate persons in the room with carbon dioxide?
Draw stock and flow of room
List relevant quantities
Create estimates for the relevant quantities
Synthesize estimates to create overall estimate
Learning Objectives
Able to use stock and flow models to make estimates
Question
Based on carbon dioxide measurements, what is our estimate of the
number of persons in the ETC?
Review the Method
State question
Plan of attack
Break down
Synthesize
Review people calculation
Carbon dioxide people calculation
We started with a question, how many people given a carbon dioxide
measurement
We decided on a model to look at this
We asked what smaller problems we could solve to take on the larger
problem
We tried to solve each of these smaller pieces
We then synthesized everything
Review notes
Chalkboard review
Using modern computation tools
We were off
What did we miss?
Fresh air entering through windows?
Breath estimates?
Air mixing?
California Drought
What questions can we ask about the drought?
Which of these questions can use a box model?
Water sankey diagram
Board Notes
Board Notes
Board Notes
Board Notes
Board Notes
Board Notes
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