Symbol T_use

The passage around this formula

…acceleration factor no longer describes what happens at service temperature. A first-order approximation for a single, unchanged mechanism follows $AF = \exp\!\left[\frac{E_a}{k_B}\left(\frac{1}{T_{\mathrm{use}}} - \frac{1}{T_{\mathrm{test}}}\right)\right]$. where $E_a$ is the mechanism’s activation energy, $T_{\mathrm{use}}$ and $T_{\mathrm{test}}$ are absolute temperatures, and $k_B$ is Boltzmann’s constant. This is a genuine, useful model — it is also only as good as the assumption that $E_a$ and the mechanism are constant over the interval being extrapolated, an assumption every accelerated-aging program…

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