Effects of PWM chopper drive on the torque speed characteristic of DC Motor

43rd International Universities Power Engineering Conference, UPEC 2008 -- 1 September 2008 through 4 September 2008 -- Padova -- 77050This paper describes a MATLAB/Simulink realization of the DC motor speed control method by controlling the voltage applied to the armature circuit using a pulse width modulated (PWM) chopper drive. Torque-speed characteristics are obtained for different values of switching frequency to demonstrate its effect on the linearity of the characteristic. The proposed simulation model is developed as a part of a software laboratory to support and enhance undergraduate electric machinery courses at Nigde University, Nigde, Turkey

Prevalence of asthma and other allergic diseases in children born after in vitro fertilisation

Background: Children born after in vitro fertilisation (IVF) are under greater risk of development of some health problems than those children born after spontaneous conception Yet it is not exactly known what the prevalence of asthma and other allergic diseases among these children is

Acute effects of different warm-up methods on free kick performance in amputee soccer players [Effetti acuti dei diversi metodi di riscaldamento sul rendimento dei giocatori amputati nel battere i calci di punizione]

BACKGROUND: There are studies documenting the detrimental effects of static stretching and useful effects of dynamic exercises. However, there is no study which has researched the acute effects of different warm-up exercises on free kick performances in amputee soccer. The purpose of this study was to compare the acute effects of static stretching and dynamic warm-up exercise on free kick performance in amputee soccer players. METHODS: Twelve amputee soccer players playing for the national team (mean age 28±7 years) were investigated in our study. This study was designed to determine the acute effects of 3 different warm-up (WU) methods static stretching (SS), dynamic exercises (DYN) and control (NS) on anaerobic performance (free kick speed performance) RESULTS: Although significant differences (P0.05) was found for SS. The data shows that there is a significant increase in free kick speed for DYN and NS according to pre and post-tests results. CONCLUSIONS: The results of this study suggest that it may be desirable for amputee soccer players to perform dynamic exercises before performing activities that require a high power output. © 2018 Edizioni Minerva Medica. All Rights Reserved