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Fig4.png Summing up a 10% every Hour, starting at 20g/h initially places us at 11.81 g/Hour at this 5h mark. The flow A->B or “Loss” looks right. There is a first order filling with the rate highest at T zero, slowing down as contents of A filling slows and AA is depleted, this then changes directi...

Using Conveyor Delay: Simplest setup a linear flow into A with a delayed outflow setup on k1 using DELAY CONVEYOR (k0, residenceT, leak, initprofile, A, residenceT). From the manual: DELAY CONVEYOR(input,ctime,leak,initprofile,inittot,initctime) Units: DELAY CONVEYOR(units,time,1/time,dmnl,units*tim...

Gosh I am so Dumb. Its because the "fractional loss rate" is a step function.
thomas

Hello Tom, I looked at the Conveyer Delay with a Loss in the example: DELAY CONVEYOR.mdl The rate of loss looks odd. Why is there no loss flow during the delay? Presumably Boxes will be being lost as they accumulate in "shipments in transit". See screenshot. Capture_delayConveyor.PNG Thomas

Thanks Tom, there is a lot of interesting stuff there that I am still going through. You are, of course way ahead of me. There are a lot more things going on in a more realistic model and its this is interesting stuff, but for the sake of trying to understand fundamentals, lets make this problem sim...

Thanks Tom, there is a lot of interesting stuff there that I am still going through. You are, of course way ahead of me. There are a lot more things going on in a more realistic model and its this is interesting stuff, but for the sake of trying to understand fundamentals, lets make this problem sim...

An alternative is to select what you want and then paste into Inkscape (a free vector graphics program). This also allow you to do minor changes to arrows, text (generally pretty it up) and then you can save it to just about any format from there.

Here is another sketch of what I was trying to do.

Hello Tom, hope you are still there! Or any one else out there! Gosh it seems a long time since looking at this problem again. I've made a simpler model of a much bigger model for testing this intestinal flow. I am still trying to model something like filling of a tube and using a FIXED DELAY to get...

Oh, I had to restart vensim. When I went back to look at my original problem, the lookup slope worked great.
see attached.

Hello Everyone, Here are some Kinetics based data input as a lookup "RawDataLookupTable". the problem is that point to point slopes must be available as input for a rate between two stocks in a larger model. See png of the graph of the output to "gradients" that I am trying to ac...

Here are my notes in a doc file in case there is someone else out there has difficulty getting started with Optimization.

Great, thanks tomfid. This has got me back on track.

Hello Vensim folks, just started looking at the optimization functionality in Vensim and seem to have fallen at the first hurdle. I set up a very simple test model A->B with first order rate (first attachment), then made a synthetic data set in excel for B (B(t)= Ao(1 - e^(-kt)) The data was copied ...

Hello Folks, Thanks for your help. Attached is the solution I have so far. I have attached the model with more descriptive labels, rather than A, B C etc, as administrator said, it makes it a bit more understandable. As tomfid said, using DELAY FIXED to control flow does not work as it cannot do a l...

Replying to Tomfid: Oh I didnt know it was called FONFOO, but isnt that what I did by testing for zero at A? Delayed flow = DELAY FIXED( AB flowThrougPipe , Delay , 0 ) where AB flowThrougPipe = IF THEN ELSE( A<0 , 0 , AB flow rate*A ) then on the other flow, "AC Flow Rate" = IF THEN ELSE(...

This is what I am trying to model: pipe_flow_sketch.pdf basically we have a level (A) feeding into a pipe (actually this is a length of intestines in my larger model that is modeling uptake of a nutrient) that ends up at level (B) according to "delayed_Flow" rate. While it is in the pipe a...