# Equation distance reduction factor ERG

1. Feb 27, 2012

### axel789

1. The problem statement, all variables and given/known data
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.

2. Relevant equations
Can someone help me to find a solution for bothh graphs

3. The attempt at a solution

I don't know how to find a solution.
Thanks for the help.
Axel

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• ###### night.jpg
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2. Feb 27, 2012

### lanedance

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

3. Feb 27, 2012

### axel789

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

#### Attached Files:

• ###### example.JPG
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4. Feb 27, 2012

### lanedance

ok so why not just draw lines?

5. Feb 27, 2012

### axel789

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

6. Feb 27, 2012

### lanedance

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

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