Pulse feeding

I am also trying to run a dynamic simulation of pulse feeding. Where I feed for the first 5 minutes and no feeding for the rest of 23hr and 55 minutes. The purpose is to simulate an experimental set up where they only feed once every 24 hr cycle and the feeding is only for 5 minute pulse feeding.

You can use a Timer (e.g. "21" that is: 2 phases and 1 signal):
[list]
[li]set the 1st period (T1) to 5 min and the 1st signal (u11) so as to feed your tank (e.g. u could be linked to a pump in a buffer tank, so u11 should be the desired feed flow)[/li]
[li]set the 2nd period (T2) to 23h55min and the 2nd signal (u21) to zero[/li]
[/list]
Mind that such "hard-switch" (u changes istantaneously from non-zero to zero) may slow down the simulation considerably - also because you may need to use a non-adaptive stepsize algorithm.
You could insert a ResponseTime model (DataTreatment block) downstream to the Timer in order to smoothen the signal (order 2 is generally fine).

Thank you Enrico. it did work, but only if you feed the reactors from a tank. It would be great if we can do it from  the inputs (Municipal wastewater).
Fasil

I see your point.
However, the influent blocks (of type state vector, i.e. Municipality, Industry and Truckload) are different from any other block in that they are not associated to a model which resides in the model library: instead the model is created, at the project level, by executing the Influent tool / wizard.
So far (2014 and upcoming 2016), the only quantities (OBJ's) that can be [b]defined via the Fractionation diagram[/b] are plain [b]parameters[/b] and [b]algebraic state variables[/b]. No input interface variable (and set to manipulated) can be defined - which is what you would need in this case.
You would also need to modify the icon itself, to expose the manipulated variable through a terminal - but this would be a minor issue.
The main one is that you cannot define a manipulated interface variable.