General Electric

About: General Electric is a company organization based out in Boston, Massachusetts, United States. It is known for research contribution in the topics: Turbine & Rotor (electric). The organization has 76365 authors who have published 110557 publications receiving 1885108 citations. The organization is also known as: General Electric Company & GE.

Detailed Magnetic Behavior of Nickel Near its Curie Point

Abstract: The temperature dependence of the initial susceptibility ${\ensuremath{\chi}}_{0}$ of nickel above the Curie point ${T}_{c}$ and the field dependence of its magnetization at ${T}_{c}$ are deduced from the data of Weiss and Forrer and found to be at variance with the simple molecular-field model. Instead, the experimental ${{\ensuremath{\chi}}_{0}}^{\ensuremath{-}1}$-versus-$T$ curve just above ${T}_{c}$ is shown to follow the simple relation ${{\ensuremath{\chi}}_{0}}^{\ensuremath{-}1}=A{(T\ensuremath{-}{T}_{c}]}^{\ensuremath{\gamma}}$, with $\ensuremath{\gamma}=1.35\ifmmode\pm\else\textpm\fi{}0.02$, in excellent agreement with the $\frac{4}{3}$-power relation recently predicted from the exact series for the Heisenberg model. From the coefficient $A$, it is deduced that ${\ensuremath{\mu}}_{0}$, the average atomic moment, is 0.642 ${\mathrm{\ensuremath{\mu}}}_{\mathrm{B}}$ and that the individual electron moments are in a state corresponding to $S=\frac{1}{2}$. At higher temperatures, the ${{\ensuremath{\chi}}_{0}}^{\ensuremath{-}1}$-versus-$T$ curve deviates from the Heisenberg-model predictions, possibly because of a gradual rise in ${\ensuremath{\mu}}_{0}$ with increasing temperature. Up to the highest field $H$ of measurement, the magnetization at ${T}_{c}$ is shown to vary as ${H}^{\ensuremath{\epsilon}}$ with $\ensuremath{\epsilon}=0.237$, which is consistent with the exponent values for an analogous empirical relationship between the density and pressure of several different gases at their critical points.

Estimating isothermal life from thermogravimetric data

Abstract: Equations are given for estimating equivalent isothermal life from thermogravimetric data and for estimating the apparent activation energy for volatilization even though the nature of the kinetic process is unknown. Illustrative data for polytetrafluoroethylene are presented. The importance of using sample temperatures, rather than furnace temperatures, is noted.