Generic Structures First-Order Negative Feedback

D-4475-2 13flow = adjustment gap * draining fractionDOCUMENT: The draining fraction and the value of the gap set the outflow to thestock. It corresponds to the decay rate, death rate, and firing rate in the above examples.UNIT: units/timeadjustment gap = stock – goal for stockDOCUMENT: The adjustment gap is the difference between the stock and the goal forthe stock. In the radioactive and population examples it is equal to the difference betweenthe stock and the implicit goal of zero, or simply the value of the stock. The adjustmentgap also corresponds to the distance to goal in the employee example.UNIT: unitsdraining fraction = a constantDOCUMENT: The draining fraction is the fraction of the gap (equal to the stock whenthe goal is zero) that is closed each time period. The draining fraction corresponds to thedecay fraction and the death fraction in the examples above.UNIT: 1/timegoal for stock = a constantDOCUMENT: This is the goal for the stock. The goal equals zero in the radioactivecompound and population systems, and corresponds to the desired number of employeesin example 3.UNIT: unitsNote: If we had a time constant instead of a draining fraction, the equation for the flowand the time constant would beflow = adjustment gap/time constantUNIT: units/timetime constant = a constant