International Journal of Applied Electromagnetics and Mechanics - Volume 13, issue 1-4

Authors: Didosyan, Yuri S. | Hauser, Hans | Toriser, Walter

Article Type: Research Article

Abstract: In contrast to existing current transformers utilizing the Faraday rotation of light polarization, the principle of operation of the new sensor is based on the direct registration of the domain wall positions in an orthoferrite, a transparent ferromagnet. The results of the measurements are not affected directly by temperature changes of Faraday rotation, birefringence, fluctuations of the incident light beam, polarization distortions in fibers, etc. The amplitude of domain wall motion remains …constant in a wide range of driving magnetic field frequencies from dc to hundreds kHz. With the further growth of the frequency the amplitude decreases in two times at 5~MHz. In the temperature range from 20°C to 130°C the domain wall mobility and the bandwidth decrease in about three times. Show more

DOI: 10.3233/JAE-2002-334

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 13, no. 1-4, pp. 277-283, 2002

Authors: Koutroulis, Ch. | Kladas, A.G. | Mamalis, A.G.

Article Type: Research Article

Abstract: The paper presents the optimization procedure of permanent magnet electrical machines, presenting important advantages in wind power generation and traction applications. Both "Internal" low remanence permanent magnet and "Peripheral" Neodymium alloy magnet rotor structures have been considered and compared. Design optimization has been performed based on the finite element method and sensitivity analysis techniques. The developed methodology precision has been checked through measurements on a 2 kW electrical machine prototype and the …good agreement with the experimental results illustrates the method suitability for permanent magnet machine design. Show more

DOI: 10.3233/JAE-2002-325

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 13, no. 1-4, pp. 285-290, 2002

Authors: Lorentzou, M.I. | Hatziargyriou, N.D.

Article Type: Research Article

Abstract: Grounding systems have to be effectively designed in order to prevent electrical installation from excessive overvoltages and potential gradients when lightning occurs or in case of short circuit. Effective design of extended grounding systems as in case of windfarms grounding is investigated in terms of combining good performance in high and in low frequencies.

DOI: 10.3233/JAE-2002-339

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 13, no. 1-4, pp. 291-297, 2002

Authors: Matlák, Zsuzsanna | Barbarics, Tamás

Article Type: Research Article

Abstract: This paper presents the analysis of the force determination that exerts an influence in the levitation-melting method model. The goal of the present study is a numerical investigation of the problem results concerning the alternation of the magnetic field modified by the sphere, which melts during the levitation-melting method. The numerical investigation is realised by global variational method, completed with the R-functions.

DOI: 10.3233/JAE-2002-336

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 13, no. 1-4, pp. 299-306, 2002

Authors: Suzuki, Takaaki | Baba, Hidehiro | Matsumoto, Eiji

Article Type: Research Article

Abstract: In this paper, the magnetic constitutive equation of the magnetoelastic material with hysteresis is presented. The proposed equation exhibits both the hysteresis and the stress dependence of the magnetization curve. To verify the constitutive equation, the magnetization under the stress is measured. In this test pure nickel is used, which has especially large stress dependence of magnetic properties. Theoretical results are found to be in very good agreement with the experimental data.

DOI: 10.3233/JAE-2002-322

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 13, no. 1-4, pp. 307-310, 2002

Authors: Iwami, Yoshio | Okazaki, Yasuo | Saito, Akihiko

Article Type: Research Article

Abstract: Stress-magnetization changes in Co-based amorphous ribbons annealed under magnetic field (magnetic field heat treatment) have been investigated. The stress-magnetization changes due to tensile stress were observed in positive increment of magnetization for the sample annealed under transversal magnetic field to its ribbon axis. However, a Co-based amorphous ribbon annealed under applied magnetic field parallel to the ribbon axis (longitudinal direction) did not show positive magnetization increment under applied tensile stress but showed …stress insensitive region in magnetization change, which extended with increasing annealing temperature. Show more

DOI: 10.3233/JAE-2002-319

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 13, no. 1-4, pp. 311-316, 2002

Authors: Chiriac, Horia | Lozovan, Mihai | Neagu, Maria | Hison, Cornelia | Lupu, Nicoleta

Article Type: Research Article

Abstract: Results concerning the influence of Mo addition and thermal treatment on the Hall effect and magnetoresistance of Co_{68.25-x} Fe_{4.5} Si_{12.25} B_{15} Mo_x (x=1; 2) ribbons in the amorphous, nanocrystallized and crystallized states are reported. The value of the Hall resistivity of the samples increases continuously with applied magnetic field up to about 7 kOe and 13 kOe for Co_{67.25} Fe_{4.5} Si_{12.25} B_{15} …Mo_1 and Co_{66.25} Fe_{4.5} Si_{12.25} B_{15} Mo_2 alloys, respectively and then it approaches saturation. For Co_{67.25} Fe_{4.5} Si_{12.25} B_{15} Mo_1 ribbons the ferromagnetic anisotropic resistivity (FAR) values are 2.78 × 10^{-4} , 2.60 × 106^{-4} and 2.84 × 10^{-4} for amorphous, nanocrystalline and crystalline states, respectively. The FAR values of Co_{66.25} Fe_{4.5} Si_{12.25} B_{15} Mo_2 ribbons are 1.35 × 10^{-4} , 1.78 × 10^{-4} and 18 × 10^{-4} for amorphous, nanocrystalline and crystalline states, respectively. Show more

DOI: 10.3233/JAE-2002-332

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 13, no. 1-4, pp. 317-321, 2002

Authors: Borcia, I.D. | Spinu, L. | Stancu, Al.

Article Type: Research Article

Abstract: The shape and the movement of the critical curves in the Preisach plane are investigated using the numerical solution of master equation with variable magnetic field and temperature. It is shown that the shape of the thermal critical curve is a curve line. The movement of the thermal boundaries is simulated in magnetization processes with constant or variable field. Using this model we can explain the dependence of the coercivity on the variation rate of the …magnetic field. Show more

DOI: 10.3233/JAE-2002-327

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 13, no. 1-4, pp. 323-328, 2002

Authors: Ioan, Daniel | Rebican, Mihai

Article Type: Research Article

Abstract: The paper describes a magnetic field inverse problem and an efficient numerical method to solve it. Starting from the experimental flux-current Φ-I data obtained using a non-uniform magnetic field device with known geometry, the B-H nonlinear characteristic of the homogeneous magnetic core is extracted. Both functions B-H and Φ-I are piecewise linear approximated with the same number of breakpoints. The correct formulation (solution uniqueness) of this particular inverse problem is discussed. The …method was successfully applied to characterize the ribbon core material of a FLUXSET magnetic field sensor used in Eddy Current Testing. In this case, the hysteresis loop and the equivalent lumped magnetic nonlinear circuit were extracted. Comparison with experimental results validates the proposed method. Show more

DOI: 10.3233/JAE-2002-338

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 13, no. 1-4, pp. 329-334, 2002

Authors: Caltun, Ovidiu Florin | Andrei, Petru | Stancu, Alexandru

Article Type: Research Article

Abstract: The shape of the hysteresis loop of MnZn ferrites depends on temperature. By increasing the temperature, the squareness of the loop increases. Consequently, the magnetic properties change the power losses and the performances of the ferrites. In this paper, a comparison is made between the calculated hysteresis loops in Jiles-Atherton model and the experimental loops. The influence of temperature and of the microstructure (size of the grains, pores and segregation) on the model's parameters is discussed.

DOI: 10.3233/JAE-2002-329

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 13, no. 1-4, pp. 335-338, 2002