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balassit

Post subject: Clarification on the 4.184 Multiplier Posted: Fri Feb 29, 2008 12:48 pm 

Joined: Fri Feb 29, 2008 12:41 pm Posts: 1

I am looking on page 11 of the 1584, equation 6.
Above it is stated that En is in J/cm^2.
Looking at the equation (6) it states
E = 4.184*Cf*En(t/.2)*(610^x/D^x)
Is the 4.184 a multiplier to convert calories to Jewels? If so, why does the document state above that En is already in Jewels? Just looking for a little clarity on this.
Thanks


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mnmurphy

Post subject: Posted: Tue Mar 04, 2008 1:51 am 

Joined: Tue Oct 02, 2007 7:23 pm Posts: 40 Location: Oak Ridge, Tennessee

Clarification on Equation 6
It is confusing for sure. This whole section here (Equation 46) is stating that it is dealing in J/cm2 in the text, but admits to cal/cm2 in the footnotes for En. The 4.184 is really converting from calories to jewels, but does not follow along. It is just the next step from going from En to E.
I think it is just an overthinking logic mistake. If you follow the text it still works out, but has required an entire addition of Appendix E, given the logic.
If you want to deal in cal/cm2 basically look at Appendix E. You go through the same equations for En, (4) and (5), but you use the Appendix E equation in lieu of Equation 6.
Now this is basically converting. If you want to deal in cal/cm2, you have a supposed En in J/cm2 from equations (4) and (5) and now you are dealing with an equation in Appendix E, that is the same as Equation (6) without the 4.184 multiplier.
I will remember this for the IEEE 1584 Meeting. Maybe there was some specific reasoning for the logic used.
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