HARMONIC ANALYSIS AND MODELLING OF MAGNETISATION PROCESS IN SOFT FERROMAGNETIC MATERIAL

The aim of this paper is to present a research of magnetic hysteresis loops of a toroidal ferromagnetic core made of electrical steel. The experimental results of induced voltage, magnetic induction and hysteresis loop obtained at different frequencies of the sinusoidal excitation magnetic field have been presented. The harmonic content of the induced voltage and magnetic induction have been calculated using Fast Fourier Transformation. Observed variation of higher harmonics with frequency has been correlated to the mechanism of magnetic domain walls damping. A variation of harmonics of the magnetic induction with the amplitude of the excitation magnetic field has been analysed and a proper mathematical model has been proposed. Furthermore, the influence of the triangularly shaped excitation magnetic field and the distorted shape excitation that produces sinusoidal induction on the shape of hysteresis loop and harmonic content of the induced voltage and the magnetic induction has been analysed and discussed

Interdisciplinary science concept maps to orient middle secondary school students learning outcomes

Abstract The initial and continuing training of natural science teachers should be implemented in interdisciplinary contexts. This paper shows how concept maps can generate training activities in which teachers of various disciplines can discuss macro concepts such as water, air, wind, temperature, motion, power, energy, etc. mapping the students’ learning pathway. Drawing concept maps and discussing them in training sessions from the perspective of students, teachers and trainers can be a decisive professional experience in changing the ways of improving concepts representations of all the actors of classroom activities and educators.</jats:p

POLYCRYSTALLINE Ni, Zn AND Ni-Zn FERRITE TARGETS FOR PLASMA LASER DEPOSITION TECHNIQUE

[[abstract]]Ni, Zn and Ni-Zn ferrites targets to by used in pulsed laser deposition of thin ferrite films were prepared by a conventional ceramic technique. The properties of the ferrites were evaluated from XRD, SEM and EDX data. The electrical and magnetical characteristics of the investigated specimens are interpreted in terms of the role played by the sintering condition on the microstructure and on stoichiometry

POLYCRYSTALLINE Ni, Zn AND Ni-Zn FERRITE TARGETS FOR PLASMA LASER DEPOSITION TECHNIQUE

[[abstract]]Ni, Zn and Ni-Zn ferrites targets to by used in pulsed laser deposition of thin ferrite films were prepared by a conventional ceramic technique. The properties of the ferrites were evaluated from XRD, SEM and EDX data. The electrical and magnetical characteristics of the investigated specimens are interpreted in terms of the role played by the sintering condition on the microstructure and on stoichiometry

Jiles-Atherton Magnetic Hysteresis Parameters Identification

This paper presents a method of fitting the magnetic hysteresis curves using a calculating algorithm within a computer programme. The calculating programme uses the equations of the Jiles-Atherton model to simulate the M(H) magnetization curve. The aim of this program is to find the values of the parameters which are part of the Jiles-Atherton model once the regression curve for a major magnetization curve obtained experimentally is found. The values of these parameters can be increased or decreased gradually. The parameters modification takes place in such a way that the root mean square deviation between the points of the two graphs, also experimentally simulated, should decrease gradually and, in the end, it should be found below the preestablished percentage value in comparison to the previous value. The procedure for minimizing the root mean square deviation has as a result the fact that the simulated curve represents the regression curve. The calculating programme considers a second method of calculating the values of the parameters by using the already found regression curve. This paper also presents the values of the Jiles-Atherton model parameters obtained by fitting the magnetization curves of several cobalt ferrites samples, sintered at different temperatures