EXACT ANALYTICAL AND APPROXIMATE ASYMPTOTIC CALCULATION METHODS TO DETERMINE THREE-DIMENSIONAL ELECTROMAGNETIC FIELD NEAR CONDUCTING BODY WITH FLAT SURFACE

The analytical solution of the three-dimensional quasi-stationary electromagnetic field problem for a current located near conducting body with a flat surface is considered. The exact and approximate solution of the problem is presented. The exact solution has no restrictions on the external field configuration, physical properties of the medium, and frequency. The approximate solution is based on an expansion in asymptotic series and has limitations: for sinusoidal field, the solution is limited to frequencies above the lower limit; for pulsed field, the solution is limited by the initial time interval of the current pulse. Based on comparison of the results of exact and approximate calculations for nonuniform sinusoidal field at the interface between the media, the admissible value of the introduced small parameter is determined. For pulsed field the proposed choice of the limited time interval for calculating electomagnetic field using the asymptotic method is justified. References 29, figures 7.

Rogowsky coil applications for power measurement under non-sinusoidal field conditions

Electric energy measurement errors depend on the design and algorithms used in electricity meters, as well as on the auxiliary and embedded sensors’ accuracy and bandwidth (or more precisely, maximum measurable frequency). Poor power quality may affect the electric energy meters accuracy, which will lead to the improper power accounting. In this article the applications of the Rogowsky coil sensors for electric energy measurement are studied. The advantages and the challenges of this sensor type implementation are discussed, and the operation scheme of the power meter for the separate measurement of the fundamental harmonic’s electric energy and the higher harmonics electric energy is proposed. The possibility of implementation of responsibility determining methods for power quality distortion is highlighted.

Analysis of New Type Permanent Magnet Synchronous Motor Based on ANSYS

Modern motor needs high speed, high efficiency, high power density and low pulsating torque, traditional rare earth permanent magnet motor manifests its limitation. Halbach motor is a novel permanent magnet motor. Analysis of Halbach motor based on ANSYS proves its merits: sinusoidal field, higher air gap flux and lower rotor yoke flux, which can reduce pulsating torque and improve power density, efficiency of the motor, these merits can improve its dynamic characteristics greatly.

Shear Viscosity of Inhomogeneous Hard-Sphere Fluids

Using molecular dynamics on Hard-Sphere-like fluids subject to an external sinusoidal field inducing density inhomogeneities and undergoing a bi-periodical shear flow, we have studied the local viscosity of the inhomogeneous fluid. It has been shown that for a slowly varying density profile the local average density model combined with the well-known models proposed in the density function theory yields a good description of the viscosity profile obtained by molecular simulation. However, for a rapidly varying density profile these models are unable to describe correctly the viscosity profile obtained by molecular simulations. So, to overcome the weakness of these models we have proposed a simple model that takes into account the effect of the angle formed by the colliding molecules and the direction of the flow.