a stock with zero slope

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Alisib
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a stock with zero slope

Post by Alisib »

Hi
As we know, stock variable is the integral of flow, if there is a stock with zero slope diagram, what could be the flow anyway?
I meant the Quality diagram in the attached file
best wishes
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Untitled.jpg
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Administrator
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Re: a stock with zero slope

Post by Administrator »

Sorry, I do not understand what you are asking.
Advice to posters seeking help (it really helps us to help you)
http://www.ventanasystems.co.uk/forum/v ... f=2&t=4391

Units are important!
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Alisib
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Joined: Mon Oct 29, 2018 4:37 pm
Vensim version: PLE

Re: a stock with zero slope

Post by Alisib »

I meant as you can see in the picture, the behavior and structure of the actual quality is clear, suppose the formula of its inflow and outflow is not clear (for actual quality), can you suggest anything (inflow or outflow) that produce actual quality behavior?
Administrator
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Re: a stock with zero slope

Post by Administrator »

So you need some model structure that produces an immediate jump/fall in the stock?

Something like the following should get you started. This causes a jump at time = 10.

some stock = integ (inflow,0)

inflow = if then else ( time = 10, 20 , 0 )
Advice to posters seeking help (it really helps us to help you)
http://www.ventanasystems.co.uk/forum/v ... f=2&t=4391

Units are important!
http://www.bbc.co.uk/news/magazine-27509559
Alisib
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Posts: 22
Joined: Mon Oct 29, 2018 4:37 pm
Vensim version: PLE

Re: a stock with zero slope

Post by Alisib »

thx
it was a good start, By the way is there any way in vensim that can help us distinguish variable? for example name the constant one? how many constant are there? how many stock and etc.
best wishes
tomfid
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Re: a stock with zero slope

Post by tomfid »

If the stock of actual quality is essentially a step function, its net flow must be a discrete event, like a PULSE.
Alisib
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Posts: 22
Joined: Mon Oct 29, 2018 4:37 pm
Vensim version: PLE

Re: a stock with zero slope

Post by Alisib »

thanks
I am really delighted to get acquainted with this site and its administers specially Tomfid who always helps me.
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