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Next: Question 3 Up: Lakes as Well-Mixed... Previous: Question 2
Aiee!

Sorry...

An impulse input function would mean all the ammonia entered the lake more or less at once, which is not what happened here.

Given that the input concentration varies periodically, reaching a maximum at 5:00 PM and a minimum at 5:00 AM, a good first approximation for the input would be the sinusoidal input function shown below. (What would the period be in this case?)

We might consider further simplifying the model by using a step input function if the difference between the maximum and minimum concentration is small or the lake is relatively large. However, the sinusoidal input function is probably the best first guess.

Sinusoidal Graph

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John Hoggard <hoggard@math.vt.edu>
Last modified: Sun Aug 10 17:40:16 EDT 1997