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Tecnologie di ripresa digitale per lo studio di fenomeni transitori in contatti non conformi lubrificati
No full textParallelogram Shaped Hysteresis Loops for Describing the Energetic Magnetic Behavior of Hysteretic Media
No full textThe characterization of the energetic magnetic behavior
of hysteretic materials and the determination of the surface
impedances are proposed. A numerical model in time domain is
adopted for the calculations. The use of parallelogram-shaped hysteresis
loops allows for simplifying the numerical formulation and
for reducing the computation time with respect to more accurate
models. Equivalent major loops have been defined starting from
the measured ones. Comparison with the modified scalar Preisach
model is presented and discussed
Experimental characterization of plasma arc dynamics in the presence of rotating magnetic field
No full textWe present the results of a measurement analysis aimed at investigating, from a phenomenological point of view, the plasma arc behavior in the presence of rotating magnetic field. In order to obtain such data, an experimental setup was assembled in our laboratory, consisting in two electrodes connected to a welding machine and three electromagnets. A digital photo camera is used to observe the phenomenon and electrical quantities are measured by means of an oscilloscope. The experiments indicate a significant interaction between the plasma and the magnetic field. Finally, measurement results are shown and discussed
Study of plasma arc dynamic into contemporary translating and rotating field
No full textThis paper deals with the stabilization of the launch mass in and out of the bore of a plasma electromagnetic launcher. Appropriately coiled windings are assumed to produce a rotating magnetic field and, as a consequence, the rotating motion of the launch package necessary for the gyroscopic stabilization. The dynamic of the plasma arc interacting with contemporary translating and rotating field inside a hollow cylinder is focused. An analysis of the possible plasma structure flow is carried out starting from recent studies and works published by other authors. Launch mass angular and axial velocity in the presence and in the absence of the rotating magnetic field are the quantities of interest. Finally, the preparation of experimental setups purposely defined is discussed
Design of Plasma Launcher with Gyro Stabilized Launch Mass
No full textThis paper concerns the design of a plasma electromagnetic launcher aimed at determining the gyroscopic stabilization of the launch mass. The basic idea is to provide the rotation to the projectile during its acceleration inside the bore by means of a rotating magnetic field. In order to create the rotating field a three-phase winding coil system is adopted. The design procedure of the main elements (the rails, the coil system and the projectile) of the electromagnetic device is described in detail. The results obtained for the specific case of a launch mass of about 8 kg with outgoing velocity of 2 km/s are reported and discussed
Analysis and Simulation of Rotating Magnetic Field Diffusion through a Parallelogram Hysteresis Model
No full textShielding Effectiveness Measurements for Ferromagnetic Shields
No full textThis paper proposes a new way to measure the shielding effectiveness of ferromagnetic shields. The procedure combines an experimental characterization of the shielding material and numerical simulations. In a first case, magnetic hysteresis is reduced to a series of equivalent B–H linear relations through an optimization procedure that is applied to a measured set of symmetric minor loops, and an equivalent multilayer linear medium is defined through a subsequent iterative procedure. In a second case, magnetic hysteresis is reduced to a simple B–H nonlinear relation, obtaining an equivalent nonlinear shield. In both cases, the obtained results are compared with the direct measurements of the shielding effectiveness at different operating frequencies, showing good agreement and the validity of the proposed method. A comparison and a discussion on the harmonic content of the attenuated field for the investigated shield geometry are reported. The same analysis is carried out for a basic diffusion problem, comparing the results with those obtained by the use of a Preisach model
Analysis and Simulation of Rotating Magnetic Field Diffusion through a Parallelogram Hysteresis Model
No full textThis paper deals with the diffusion of rotating electromagnetic fields into hysteretic materials. A simplified vector formulation based
on a parallelogram hysteresis model has been investigated, in order to significantly reduce the computational effort. Vector saturation
and loss properties are discussed. The whole simulation has been done by the use of a finite-element time-domain algorithm
About the role of hysteresis in magnetic penetration at extremely low frequency
No full textIn this paper a discussion about the role of magnetic hysteresis on the magnetic field distortion and attenuation is presented. A one-dimensional FDITD algorithm has been used to evaluate the weight of hysteresis in determining the magnetic field attenuation for a magnetic iron hollow indefinite thin cylinder. On the basis of such an analysis a second 2D-FEM numerical algorithm has been implemented taking into account only the virgin magnetization curve, therefore, not describing the hysteretic cycles and simulations have been done for a finite thin hollow cylinder geometry. To investigate the approximation due to such a strategy an experimental setup has been implemented and results have been compared. Data have shown that for the investigated geometry and materials the error remains small validating the simplified methodology at least from an engineering point of view
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