NUMERICAL CHARACTERIZATION MODEL OF VECTOR HYSTERESIS FOR MAGNETIC MATERIALS
The paper presents a numerical method based on Preisach model for the characterization and modelling of hysteretic magnetic materials exhibiting vector hysteresis, with acceptable accuracy, based on minimal material measurement data. The identification approach based on the Everett distribution function is a way to obtain accurate numerical solutions when the experimental data of the magnetic material are scarce, for instance: there are known only the initial magnetization curve and the upward major branch for two directions (rolling and transverse ones). The comparison between the measured and simulated major loop curves for another magnetization direction shows good agreements.
An efficient procedure for modeling complex hysteresis processes in ferromagnetic materials
A simple mathematical formalism for describing arbitrary hysteresis processes is presented. The information required to apply this formalism to a given magnetic material can be obtained with relatively little effort from experimental hysteresis curves such as normal loops or, in special cases, from just the initial curve. The basic physical model is that of Preisach. A more convenient, less widely known, treatment of this modes by Everett to which we have applied magnetic symmetry constraints leads to a succinct description of hysteresis processes. We have applied this procedure to calculate losses in nonoriented electrical steel laminations. The fully non-linear electromagnetic field equations were solved on the computer for this simple geometry with no restrictions on the hysteresis paths. The calculated losses agreed at the 5% level with experimental losses for a wide range of frequencies and inductions.
General expression for the density effect for the ionization loss of charged particles
The equations for the density-effect correction $\ensuremath{\delta}(X)$ for the ionization loss as given in a previous paper have been extended to the case where $\ensuremath{\delta}({X}_{0})\ensuremath{\equiv}{\ensuremath{\delta}}_{0}g0$. Here ${X}_{0}$ is the lower limit of the range ${X}_{0}lXl{X}_{1}$, where a particularly simple expression for $\ensuremath{\delta}(X)$ applies; $X={log}_{10}(\frac{p}{{m}_{0}c})$, where $p$ is the momentum and ${m}_{0}$ is the mass of the incident particle. The case ${\ensuremath{\delta}}_{0}g0$ applies directly to the calculation of $\ensuremath{\delta}(X)$ for conductors (metals).