Generic Structures First-Order Negative Feedback
Generic Structures: First order negative feedback loops
Generic Structures: First order negative feedback loops
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32D-4475-23.1 Model DiagramStockINITIAL STOCKflowadjustment gapDRAINING FRACTIONGOAL FOR STOCKFigure 16: Vensim Equivalent of Figure 5: <strong>Generic</strong> ModelDocumentation for the <strong>Generic</strong> Model(01) adjustment gap=Stock-GOAL FOR STOCKUnits: unitsThe adjustment gap is the difference between the stock and thegoal for the stock. In the radioactive and population examplesit is equal to the difference between the stock and the implicitgoal of zero, or simply the value of the stock. The adjustmentgap also corresponds to the distance to goal in the employeeexample.(02) DRAINING FRACTION=a constantUnits: 1/timeThe draining fraction is the fraction of the gap (equal to thestock when the goal is zero) that is closed each time period.The draining fraction corresponds to the decay fraction and thedeath fraction in the examples above.(03) FINAL TIME = 100Units: timeThe final time for the simulation.(04) flow=adjustment gap*DRAINING FRACTIONUnits: units/timeThe draining fraction and the value fo the gap set the outflowto the stock. It corresponds to the decay rate, death rate, andfiring rate in the above examples.
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