Generic Structures First-Order Negative Feedback

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20D-4475-24 Since STELLA specifies the outflow as negative in the equations of the stock, we will assume thedraining fraction must be positive. Therefore, the simplest negative feedback loop requires a positivedraining fraction for the outflow of the stock.
D-4475-2 21To sum up, asymptotic growth and decay require an initial value of the stock otherthan zero and have a constant halving time. The rate at which the decay occurs increaseswith the value of the draining fraction. If either the stock or the draining fraction is zero,the outflow is also zero and equilibrium exists.Look over Figure 10 and all the graphs of simulation included in the paper. When you feelconfident about your understanding of the behavior, you should go on to the exercises inthe next section.6. Using Insights gained from the generic structureWe have seen many examples of different systems, with both implicit and explicitgoals with the same basic structure. Now, we apply the insight we gained fromunderstanding the generic structure and its behavior to understand the behavior of othersystems.To do the exercises, you need not simulate the models; hand computation shouldsuffice. However, after answering the questions, we encourage you to build andexperiment with the models.6.1 Exercise 1: Radioactive DecayIn section 2.1 we introduced the simple structure of radioactive decay. Carbon-14decays into the stable element Nitrogen with a half-life of 5700 years.1. Using the above information, draw the stock and flow diagram of the decay of Carbon-14.2. What is the value of the time constant? the draining fraction?6.2 Exercise 2: Package DeliveriesBelow is a simple negative feedback system.
Page 1 and 2: D-4475-2 1Generic Structures:First-
Page 3 and 4: D-4475-2 3Table of Contents1. INTRO
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Page 7 and 8: D-4475-2 71. IntroductionGeneric st
Page 9 and 10: D-4475-2 9A simple negative feedbac
Page 11 and 12: D-4475-2 11number of employeesfirin
Page 13 and 14: D-4475-2 13flow = adjustment gap *
Page 15 and 16: D-4475-2 153.3 Model BehaviorThe ch
Page 17 and 18: D-4475-2 171: STOCK 2: STOCK 3: STO
Page 19: D-4475-2 195. Summary of important
Page 23 and 24: D-4475-2 23Figure 12. Company Downs
Page 25 and 26: D-4475-2 25UNIT: atomsOUTFLOWS:rate
Page 27 and 28: D-4475-2 27Vensim Examples:Generic
Page 29 and 30: D-4475-2 292.2 Example 2: Populatio
Page 31 and 32: D-4475-2 31The initial time for the
Page 33 and 34: D-4475-2 33(05) GOAL FOR STOCK=a co
Page 35 and 36: D-4475-2 35Graph of Stock with diff

Generic Structures First-Order Negative Feedback

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