Equation distance reduction factor ERG

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Homework Statement


Hello,

I'm searching for the formula for the 2 pictures in attachment.

The first is de reduction factor day and the other is the reduction factor night.
As example for the factor day: on X I put the distance 10 Km, then I choose the value off L = 3
then I have as reduction factor on the Y = 0,3 or 30%
For the reduction factor night it is the same way off working but with other curves.


Homework Equations


Can someone help me to find a solution for bothh graphs


The Attempt at a Solution



I don't know how to find a solution.
Thanks for the help.
Axel
 
Attachments
  • Line graph of reduction factor (0.0 to 1.0) against point source hazard distance (0 to 70 km), with curves labelled L = 0.5, 1, 2, 3, 5 and 10 km; each curve rises steeply and levels off toward 1.0.
    day.jpg
    45.7 KB · Views: 423
  • Line graph of reduction factor (0.0 to 1.0) against point source hazard distance (0 to 70 km), with seven curves labelled L = 0.5, 1, 2, 3, 5 and 10 km, each rising and levelling off.
    night.jpg
    49.5 KB · Views: 387

Discussion

Welcome to PF - generally you have to attempt some work and we'll help you through rather than just giving an answer. For clarity, it also helps if you give the whole question as it was written, with an extra info you can think of

Now without knowing more, they look like an exponential function may do the job well
 
Hello,

In attachment an example from a solution if you use the graph by drawing lines.

I already searched the internet and I thought it was a gaussian model but it was far more complex then the graphs.

It's not that I am not trying but I don't know where to start and I my math is rather rusty.

Thx,

Axel
 
Attachments
  • Text page titled Example Sub-type 2 giving six numbered steps for reading the ERG graph to get a hazard area distance for a sulphur dioxide line source release, with worked values 2.1 km, 0.25 and 0.525 km, plus notes for XLG and LRG chlorine cases.
    example.JPG
    81.7 KB · Views: 421
Because I would like to put them in a program i made in excel who draws automatically
the grid and the coordinates of the danger zone.
Also when i give courses in CBRN , here it is Chemical, I can give the exact value and not
"something around that number".

You could call me a detailist, but that's my approach off giving courses in CBRN.

Thx,

Axel
 
ok, well I don't know what cbrn is...

however as mentioned I would try a simple exponential as a first try
 

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