ASIM User Forum - [A variation file of a 14 days duration]

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From: laila Bahgat (lbahgat@yalla.com)
Date: 03/26/2003

I'll very much appreciate your help regarding this point:

I met some difficulties in setting the options of the new
variation menu to represent the duration of my influent
file. My file records the values of model fractions for a
period of 14 days where data is recorded every 15 minutes
(typical to the influent data files provided by the COST
simulation benchmark).

As the cycle represents 1 day I've set the duration to 24
hours, and the number of points in a cycle to 96 points (4
times/hr * 24 hours).
Thus the data of one day only was copied from the Excel file
to the variation form.

It says in the online help that the simulation period can be
set to several cycles when dynamic simulation is chosen,
but how to make the variation form take more values than
those of one cycle.

Another issue I've noticed that if the number of rows of the
copied Excel book column is large i.e. whenever a whole
column of my file is marked & copied (14 days * 24 hrs * 4
times per hr), this does not activate the (from clipboard)
option. 

Thank you very much for your feedback.



Reply #1
From: Fankhauser Rolf (asim@eawag.ch)
Date: 03/27/2003
The idea of the variation file is that you define there one
cycle. You may simulate several cycles in the dynamic
simulation but for each cycle the same variation is taken.

There are two ways to by-pass this restriction:

- you choose a cycle length of 14 days. But then you can
define only 96 variation values for this period. Your time
resolution is only 3.5 hours i.e. 14 times less than your
data. 

- you choose a cycle of one day. Choosing 96 variation
values correspond to a time resolution of 15 min. But then
you have to define 14 variation files, each for one day of
the period of 14 days. Then you have to load each variation
file and perform a simulation. The state of the plant is not
reset at the beginning of the simulation. I admit that this
procedure is time-consuming and not very elegant :-(  

I will ask Prof. Gujer if there is other possibility to
simulate it.   

  

  


Reply #2
From: laila bahgat (lbahgat@yalla.com)
Date: 03/28/2003
Many thanks for the feedback.



Reply #3
From: Willi Gujer (gujer@eawag.ch)
Date: 08/27/2003
A variation with a time resolution of 15 min is only
required if your degradation is way beyond 99%. Typically it
is sufficient to reduce your time resolution to say 2 hrs
per step. This means that you may model your 14 days with
two consecutive variation files.

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