Information

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The Real output y is obtained by dividing the current amount in a material stocku_level by the (positive) rate of its outflow u_rate. According to Little's Law—a famous result from queueing theory—the output y will be equal to the mean time of residence in the stock if the system is in equilibrium.

Notes

Both, the amount in the stock (u_level) and the rate of outflow (u_rate) have to be positive; negative values will be assumed to be zero.
Should the rate of outflow be zero (or negative) the parameter durationAtZeroRate (default = Constants.inf will be used to obtain the output.

Acknowledgements

Additional information can be found on Jim Hines' Molecules of Structure website: →Residence Time.

durationAtZeroRate	Value: inf Type: Time (s) Description: Value for duration if the rateOfDepletion becomes zero

Connectors (3)

	u_level	Type: RealInput Description: Current level of work to do or simply level of stock being depleted by flow
	u_rate	Type: RealInput Description: The rate at which the stock is drained or the tasks being completed
	y	Type: RealOutput Description: Time needed to complete work or drain stock

u_level

Type: RealInput

Description: Current level of work to do or simply level of stock being depleted by flow

u_rate

Type: RealInput

Description: The rate at which the stock is drained or the tasks being completed

Type: RealOutput

Description: Time needed to complete work or drain stock

Components (3)

	residenceTime	Type: Division_Guarded Description: Average time of residence in a stock that is being depleted
	currentLevel	Type: ZeroIfNegative Description: Current amount that is being depleted
	rateOfDepletion	Type: ZeroIfNegative Description: Rate of Depletion