# UVI formulae

Discussion in 'Math' started by jagjit Sehra, Oct 10, 2008.

1. ### jagjit Sehra Thread Starter Member

Feb 29, 2008
25
0
Hi Folks,
hope everone is well, I have a formulae which calculates the safe exposure time for Ultra Violet light. The formulae is shown below:

Iuv= Ker.∫Eλ . Ser(λ) dλ

http://meteo.lcd.lu/papers/uv/uvi/uvi_01.html

I would appreciate it, if someone can give me a hand in solving this equation.

Would it be solved using integration in parts method. Also how do I deal with lambda.

Thanks Jag.

2. ### Mark44 Well-Known Member

Nov 26, 2007
626
1
It would be helpful to know what the expressions in your intregral represent. What is Ker? What is E? What is λ? Does Eλ mean E times λ? What do the periods mean? Multiplication?

Is there some connection between your formula and the link you provided? It seems to be not much more than an ad for a UV monitor.

Mark

3. ### triggernum5 Active Member

May 4, 2008
216
0
I don't know what ker/ser are, it doesn't explain it this way in your link..
Logically though, it seems to be an integration of Energy across wavelength (λ) multiplied by some kind of adjustment function (ser) to correlate the simple energy across spectrum integration to real world effect.. So you'd need to know how to compute that ser function..

4. ### Diablo Member

Aug 24, 2008
13
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As mentioned by the others, first start by getting the expression of the function ser(), Ker and E.
regards

5. ### jagjit Sehra Thread Starter Member

Feb 29, 2008
25
0
Sorry Folks,
I didnt give enough information about the formulae.

Iuv = Ker.∫ Eλ . Ser (λ) dλ

Eλ is the solar spectral irradiance expressed in W/(m2.nm) at wavelength λ and
dλ is the wavelength interval used in thesummation.
Ser(λ) is the erythema reference action spectrum, and ker is a constant equal
to 40 m2/W.

The upper and lower limits for the integral are 400 nm and 250 nm.

It is a UV monitor formulae which calculates the safe time of exposure before the harmfull rays cause damage.
I dont know how to make a start on it, can someone please give me some advice.

Thanks Jag.

6. ### guitarguy12387 Active Member

Apr 10, 2008
359
12
Unless somebody else understands better what you're trying to say, i'd think you'll still need an expression for Ser(λ) and Eλ (unless Eλ is a constant...) for your particular problem.

May 4, 2008
216
0