On Wed, Feb 6, 2013 at 11:57 AM, David Roberson <[email protected]> wrote:
You mention one of the situations that I have a bit of concern about. The > curve fit is achieved by using the internal curve fitting routine of Excel > in its X-Y chart menu. I am fortunate that it is a quadratic equation that > is required and not a higher order. If excess heat were an issue I feel > confident that it would impact the calibration accuracy with its non linear > behavrior versus temperature becoming evident. > > The closeness of my calculated input power to the actual is an > indication that excess power is not having a large impact. Also, there are > enough pairs of points covering enough of the axis to rule out luck in > obtaining the proper coefficients. As you know a perfect fit is always > possible if only 3 pairs of points is available. We used 8 pairs if I > recall correctly. > With a setup like the one they're currently using for the USA cell, one wants to see on the order of 10-20 W excess power to have a sense that it is not some threshold effect. So even if we saw evidence for 1-2 W excess power, I doubt this would be convincing for anyone. It would be nice if Celani could find the time to visit the MFMP and help them set their cell up. Eric
