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Unformatted text preview: R is a rate, the amount of something that flows in a given time period (per unit time); L is a level, the accumulation of rates added to an initial condition; A is an auxiliary variable. Levels and rates are necessary to describe a situation. Auxiliaries are used to break down rate equations into manageable parts, to convert flows from one type to another and to provide information to change/control rates, which is particularly useful when we come to writing sets of equations from the SD diagram. Rules of this logic, captured in Figure 4.6, are as follows. A level in a loop can only be preceded by a rate. < previous page page_69 next page >...
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This note was uploaded on 04/21/2011 for the course MGT 03 taught by Professor Kasra during the Spring '11 term at Tanta University.
- Spring '11