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  • Author: Sławomir Szymański x
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Open access

Jakub Bernat, Jakub Kołota, Sławomir Stępień and Grzegorz Szymański

An inductance lookup table application for analysis of reluctance stepper motor model

This research presents a method of modeling and numerical simulation of a reluctance stepper motor using reduced finite-element time-stepping technique. In presented model, the circuit equations are reduced to non-stationary differential equations, i.e. the inductance mapping technique is used to find relationship between coil inductance and rotor position. A strongly coupled field-circuit model of the stepper motor is presented. In analyzed model the magnetostatic field partial differential equations are coupled with rotor motion equation and solved simultaneously in each iterative step. The nonlinearity problem is solved using Newton-Raphson method with spline approximation of the B-H curve.

Open access

Sławomir Szymański, Katarzyna Szczerba and Violetta Konstanty-Kurkiewicz

Abstract

Aim. The aim of the study was to evaluate the effectiveness of preventive perinatal antibiotic therapy on the occurrence of an earlysymptomatic infections in newborns. Material and Methods. The studied material consisted of data obtained from medical records of 1,328 born alive infants and their mothers. Advanced parameters were described with appropriate numbers, arithmetic means, standard deviation, median as well as minimum and maximum values. The level of statistical significance was p<0.05. Results. When it comes to 6.62% of newborns, they demonstrated the presence of early signs of infection. The Group B Streptococcus (GBS) infection was found in 14 cases, but only in 5 of them pure GBS strains were isolated. E. coli bacteria was reported in 33 neonates, while the other bacteria naming: Enterococcus faecalis, Enterobacteriaceae, taphylococcus epidermidis, Staphylococcus aureus were isolated from 42 newborns. Among 24 newborns showing clinical signs of infection and positive indicators of inflammation in laboratory tests, simultaneously negative results of bacteriological cultures were reported. Conclusions. In connection with the introduction of an obligation to perform tests for GBS, amount of used antibiotics is increasing. However, the effectiveness of intrapartum antibiotic therapy and its prevalence appear to be unsatisfactory. The color of amniotic fluid may have an impact on the occurrence of intrauterine infection, including early symptoms of the GBS infection.

Open access

J. Bernat, S. Stępień, A. Stranz, G. Szymański and J.K. Sykulski

Abstract

An optimal control theory based method is presented aiming at minimizing the energy delivered from source and the power loss in a stepper motor circuit. A linear quadratic current regulator with an infinite time horizon is employed and its appropriateness for this type of a problem explained. With the purpose of improving the accuracy of the control system, the self and mutual inductances of windings are calculated using a finite element model. The numerically computed results are verified experimentally.