ExponentialDecayA stock is drained at a rate proportional to its content 
This information is part of the Business Simulation Library (BSL).
ExponentialDecay is identical to →ExponentialDecline, e.g., the connected stock is drained at a rate proportional to its content into a sink with infinite capacity outside the border of the system in focus. Instead of using a fractional rate λ to describe the process, we are using the mean residence time τ (aka mean lifetime or the exponential time constant) to parameterize the process:
The mean residence time can be given either as a constant parameter (residenceTime) or as a continuous time input u.
The effective rate of decay with respect to a connected stock x at any time will be given by
hasConstantResidenceTime 
Value: false Type: Boolean Description: = true, if the constant residence time is used instead of the real input u 

residenceTime 
Value: 1 Type: Time (s) Description: Constant time of average residence (optional) (decaying.residenceTime) 
y 
Type: RealOutput Description: Rate information 


y1 
Type: RealOutput Description: Rate information 

y2 
Type: RealOutput Description: Rate information 

massPort 
Type: FlowPort Description: Inflow to or outflow from connected stock 

u 
Type: RealInput Description: Residence time input 
parResidenceTime 
Type: ConstantConverterTime Description: Constant residence time (optional) 


decaying 
Type: Decay 

drainedMaterial 
Type: Cloud Description: System boundary  the stock will be assumed to have infinite capacity 