ON THE THREE-DIMENSIONAL PAULI EQUATION IN NONCOMMUTATIVE PHASE-SPACE

In this paper, we obtained the three-dimensional Pauli equation for a spin-1/2 particle in the presence of an electromagnetic field in a noncommutative phase-space as well as the corresponding deformed continuity equation, where the cases of a constant and non-constant magnetic fields are considered. Due to the absence of the current magnetization term in the deformed continuity equation as expected, we had to extract it from the noncommutative Pauli equation itself without modifying the continuity equation. It is shown that the non-constant magnetic field lifts the order of the noncommutativity parameter in both the Pauli equation and the corresponding continuity equation. However, we successfully examined the effect of the noncommutativity on the current density and the magnetization current. By using a classical treatment, we derived the semi-classical noncommutative partition function of the three-dimensional Pauli system of the one-particle and N-particle systems. Then, we employed it for calculating the corresponding Helmholtz free energy followed by the magnetization and the magnetic susceptibility of electrons in both commutative and noncommutative phase-spaces. Knowing that with both the three-dimensional Bopp-Shift transformation and the Moyal-Weyl product, we introduced the phase-space noncommutativity in the problems in question.

A wall-thinning measuring method based on magnetic permeability perturbation

In the determination of metal thickness by traditional electromagnetic nondestructive testing methods, the material’s electrical conductivity and magnetic permeability are required but practically unavailable or inexact. In this paper, a wall-thinning measuring method based on magnetic permeability variation of steel pipes is proposed. The direct current magnetization is applied to the ferromagnetic material, the internal magnetic field perturbation caused by the wall-thinning brings the permeability perturbation in the surface layer and be sensed by eddy current probe. The simulation results show that the permeability perturbation is closely related to wall thickness loss. The experiment results show that the signal amplitude increases with the thickness of the wall-thinning and the new method can measure the 10% wall-thinning of pipe. Finally, theoretical range of magnetization current values are discussed. The new method takes advantage of the changes in permeability and is not limited by thickness of object to be detected.

INFLUENCE OF CHARACTERISTICS OF A NONLINEAR TRANSFORMER TO WORK THE INVERTER

The article deals with the modes of switching on an inverter with a sinusoidal output voltage when working with a nonlinear transformer. The study is implemented by simulation modeling in Simulink Matlab. Simulation is carried out using the SPS model of a nonlinear transformer with various core magnetization curves. It is shown that a soft start of the inverter, performed by a gradual increase in the sinusoidal modulating voltage, eliminates in-rushes of the primary current and the magnetization current, regardless of the modulation voltage switching angle. The process of forming a hysteresis loop for a given magnetic flux is considered. The time diagrams of the direct starting-up the converter are given at various values of the modulation voltage initial phase for a core with a hysteresis loop. It is shown that the statistical characteristics of the inverter do not depend on the type of the transformer’s core magnetization curve.

Wideband Self-Calibration Method of Inductive CTs and Verification of Determined Values of Current and Phase Errors at Harmonics for Transformation of Distorted Current

Self-calibration of a designed wideband inductive current transformer (CT) was carried out in the ampere-turns condition. This method does not require a reference transducer. The values of current and phase errors at the harmonics of frequencies from 100 Hz to 5 kHz were determined for the distorted primary current of the rated main frequency equal to 50 Hz. These results were verified based on the comparison of values measured between two CTs and calculated as the difference between values obtained from their calibration. Moreover, from vectorial diagrams drawn for transformation of the higher harmonics, the source of the change in the values of current and phase errors with frequency is explained. Furthermore, the method for calculation of the values of the corresponding harmonics of the current associated with the active power losses in the core and the magnetization current is presented.

The Control of Squirrel-Cage Induction Electromotor with Constant Magnetization Current

In this paper, we study the control algorithm of electromagnetic torque and rotation speed of squirrel-cage induction electromotor with constant magnetization current. We can ensure the constant magnetization current by acting on stator voltage vector. We distinguish two methods of construction of the given magnetization current. The first method is based on variation of stator voltage amplitude from the information just of rotor rotation speed. The second method is based on the stator voltage frequency and amplitude from the stator current information. The second method permits to influence the characteristic equation roots of the control system and to have magnetization current dynamic properties.

Spintronics with metallic nanowires

This article focuses on spintronics with metallic nanowires. It begins with a review of the highlights of spintronics research, paying attention to the very important developments accomplished with tunnel junctions. It then considers the effect of current on magnetization before discussing spin diffusion and especially spin-dependent conductivities, spin-diffusion lengths, and spin accumulation. It also examines models for spin-polarized currents acting on magnetization, current-induced magnetization switching, and current-driven magnetic excitations. It concludes with an overview of resonant-current excitations, with emphasis on spin-valves and tunnel junctions as well as resonant excitation of spin-waves, domain walls and vortices. In addition, the article reflects on the future of spintronics, citing in particular the potential of the spin Hall effect as the method of generating spin accumulation, free of charge accumulation.