System Dynamics Modules
First Order Linear Positive Feedback
A first-order system contains only one stock (level or accumulator).
Systems are described as linear systems when the algebraic expressions
controlling rate(s) of flow into the system, that is, creating
a change (at any point in time) in the state
variable ‘S’ STATE OF SYSTEM are simply the product of
a constant and the current value of S. Rate of
change of state is the product of the current state
of the system and a constant.
A first-order positive feedback
loop has the effect (each time we calculate it) of
adding to S an amount (where the constant is a
Fractional Growth Factor ‘g’) which is larger than the previous
time we calculated it. Consider a series of calculations at
times t0, t1, t2 ... tn, with the initial
value of S being S0 and a Fractional Growth Factor
g operating on the inflow.
The description of the module is
The module coded in Powersim Studio is
A PowerSim Example using this module is
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