Talk:Laser flash analysis

I'm not sure if the formula for alpha is right. The original paper says 1.388*L^2/ (\pi^2*t_{1/2}), which is quite the same, but just quite! --134.176.16.145 (talk) 08:56, 12 June 2014 (UTC)
 * The formula is right. The original paper says $$1.38 L^2/ (\pi^2 t_{1/2})$$, but it seems to be a mistake; the numerical constant is the ω solving equation 6 for V = 1/2 which is about 1.370. The correct formula would thus be $$1.370 L^2/ (\pi^2 t_{1/2})$$ which is the same as $$0.388 L^2/ t_{1/2}$$ Skåningiexil (talk) 22:33, 8 August 2015 (UTC)
 * Indeed. The solution is as follows. $$0.5 \Theta_\infty =\Theta_\infty \left [1 + 2 \sum_{n=1}^\infty(-1)^n \exp \left ( -n^2 \frac{t_{0.5}}{\tau} \right ) \right ]$$, where $$\tau = \frac{l^2}{\pi^2 \alpha}$$. The equation is a special case of the Theta function where $$0.5 = \vartheta_4(0, \exp(^{-t_{0.5}}/_{\tau}))$$. Solving, $$^{t_{0.5}}/_{\tau} = 1.36975597849933 \ldots$$ and, $$\frac{1.36975597849933 \ldots}{\pi^2} = 0.13878529704272 \ldots \approx 0.1388$$. rolandog (talk) 23:57, 1 March 2017 (UTC)

What are the units fo these equations? This is missing in this article and is wrong till they are given. Kakila (talk) 15:12, 19 March 2017 (UTC)
 * It seems that units are cm^2/s based on Eq.1 of the first reference. Kakila (talk) 15:26, 19 March 2017 (UTC)
 * 原文是错误的 103.172.183.232 (talk) 06:32, 27 May 2024 (UTC)