You did not answer the information I need:
[quote]
Why the equations are the same if the output is connected to the input?
I believe the above equations should be modified if the output is connected to the input (a feedback loop).
That is the part which I do not understood!
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And I do not understand what you said:
[quote]need another thing. I need to could move tree flows, the first Qi, the enter, the second, to pass from the first to the second tank, and the third, to empty the second tank...
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I need to could move tree flows ??? ??? ???, the first Qi, the enter???
to pass from the first to the second tank ??? ??? ???
to empty the second tank ??? ??? ??? Do you mean a control to empty the second tank? ???