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Abstract: The design and analysis of a small prototype of a magnetic levitation system at low-speed using a Halbach-type magnet array is presented here. For that purpose, we have arranged a copper rim over a carbon fiber wheel, which is driven by an electric motor in presence of the magnet array, in such a manner that allows performing the experiment readily. The analysis of the system is undertaken under a two-dimensional (2D)-approach which permits computing and extending the study of our model to higher speeds. Our work is completed with a series of experimental measurements of lift and drag forces for different circumstances. Initially, the drag force is significant but after the compensation speed (when both forces balance) it slowly decreases. Conversely, the lift force becomes progressively bigger in such a manner that it attains quickly noteworthy values. We observe that the theoretical compensation speed is always minor than the experimental one and that the measured values for both forces are slightly smaller than the expected, although the main features of the experiment are well matched by our numerical simulation. [Copyright &y& Elsevier]

Abstract: Study of temperature effects on magneto impedance (MI) ratio in Co68.15Fe4.35Si12.5B15 amorphous wires is here studied. Amorphous wires of 130μm in diameter were prepared by in-rotating-water quenching technique. During MI measurements as a function of temperature, a decrease of MI ratio has been observed as the number of temperature sweeps increased. These wires have been subjected to different temperature sweeps beginning in 80K until 300K and slowly increasing the range until 400K in order to detect a critical temperature. Such critical temperature has been found close to 375K. The decrease of MI ratio is due to thermal diffusion and a change of the energy of the amorphous state as a consequence of the fact that the amorphous state is a meta stable state. It is believed that, at that temperature, atom diffusion and stress annealing take place and the state moves to a low-energy state following a dynamics in which the time when the sample is subjected to diffusion is important. [Copyright &y& Elsevier]