In this paper, we have investigated the heating power of magnetic fluid in the AC magnetic field. A sample of magnetic fluid has been used, with 10.57 % mass concentration that contained maghemite ?-Fe2O3 particles dispersed in mineral oil. We present an improved experimental system, which is capable of determining the loss mechanism, using two different approaches; calorimetric measurements and the method of magnetic measurements. It turned out, that the proposed magnetic measurement method proved to be an alternative in the process of determining losses.
COBISS.SI-ID: 13823510
Electrical discharges in gases represent a complex problem in high-voltage techniques. The paper presents the findings that have been used to build a model of flashover in gases, designed for use in engineering practice. The model is based on the electrostatic FEM computation and on the value of the flashover electrical field intensity in air. The model has been used to compute the flashover for two and the special three-electrode spark gap. Computation results are compared to the measured results obtained on the experimental three-electrode spark gap prototype. They show good agreement.
COBISS.SI-ID: 13874966
The paper presents a modofied Lindsted-Poincare (ML-P) method with multiple time scales to extend the applicability of the perturbation technique for computation of almost periodic oscillations in damped multiple degree-of –freedom dynamical systems with strongly cubic non-linearities. The results are compared with results of the Incremental Harmonic Balance method (IHB) to show the efficiency and advantages of the proposed method.
COBISS.SI-ID: 13917718
This paper describes a computer simulation of diesel spray formation and the locations of self-ignition nuclei. The spray is divided into small elementary volumes, in which the amounts of fuel, fuel vapors and air as well as mean, maximum, and minimum fuel droplet diameters are calculated. The total air/fuel and air/fuel-vapor ratios are calculated for each elementary volume. The paper introduces new criterion for determining self-ignition nuclei. A comparison of computed points to the highest self-ignition probability and the measured points, where self-ignition occurred, shows good matching.
COBISS.SI-ID: 13778710
Synchronous reluctance motors can be used in BLAC or BLDC drives as well. The main obstacle for wider use of this motor in drives is lower torque density and lower power factor than can be found in permanent magnet synchronous motors of similar size. The aim of paper is to present how the quantity of PM materials, placed in the rotor barriers, influences the motor characteristic for different load levels in dependency on voltage level and speed. By appropriate adding of PM material in the machine used in the analysis, the unity power factor over a wide range of load and speeds can be achieved.
COBISS.SI-ID: 14705942