Search results for " MOTOR"
showing 10 items of 1044 documents
Digital demodulation for fast set-up of sensorless PMSM electrical drives based on magnetic anisotropy
2009
This paper presents a demodulation algorithm applied to the sensorless control of permanent magnet synchronous motors (PMSM). The sensorless control technique reported in this paper is based on the injection of high frequency voltages to the stator so that the motor currents contain information on the rotor position. This information is then extracted by an appropriate demodulation technique. The presented demodulation algorithm is based on spectral analysis of the signal produced by the sensorless control technique because this is fully characterized and presents not ambiguous correlation between current harmonic content and rotor position. The most important feature of the demodulation al…
Race profiles of rowers during the 2014 Youth Olympic Games
2016
Aim: Strategy plays a relevant role. The purpose of this study was to analyze the race profiles of youth athletes competing at the 2014 Youth Olympic Games over a distance of 1000-m. Methods: According to the competition outcome of sculling and sweep events, 48 male and 48 female youth (17–18 years) rowers were divided in medallist (W), not medallist (NW), qualified (Q) and not qualified (NQ) athletes. Time at 0–500 m (T1) and 500–1000 m (T2) was considered. The average speed for T1 and T2 were normalized in relation to the average speed of the whole race. ANOVA for repeated measures was applied to performance 1xJ and 2-J during qualifying: 2 (sex: females vs. males) 9 2 (outcome: qualified…
Anaerobic test on rowing ergometer in young rowers
2012
PURPOSE: Performance over 2000m on a rowing ergometer is dependent upon the functional capacity of both the aerobic and anaerobic energy pathway. The purpose of this study was to assess the relationship between anaerobic power and indoor performance over 2000m in youth rowers. METHODS: Six youth rowers, 3 males and 3 females mean age 14 (range 13 – 15), performed, on a separate occasion, two maximal ergometer power tests, on 20” and on 60”, and a maximal 2000m ergometer time trial. All evaluations were performed on a Concept II model D air braked rowing ergometer (Concept2, Nottingham, UK). Average speed over 2000m (V) and average power over 20” (W20) and over 60” (W60) were measured. The d…
Pirmsskolas vecuma bērnu sīkās motorikas attīstība pareiza satvēriena veidošanai
2019
Kvalifikācijas darba pamatā ir tēma: "Pirmsskolas vecuma bērnu roku sīkās motorikas attīstība pareiza satvēriena veidošanā." Pētījuma mērķis: noskaidrot dažādu spēļu paņēmienu un metožu izmantošanas efektivitāti sīkās motorikas attīstībā un pareiza satvēriena prasmes veidošanās process bērniem no 4 līdz 6 gadu vecumam. Darbs sastāv no divām daļām - teorētiskās un praktiskās. Teorētiskajā daļā tiek analizēta zinātniskā, metodiskā, pedagoģiskā un psiholoģiskā literatūra par roku sīkās motorikas attīstību pirmsskolas vecuma bērniem (4-6 gadi), kā arī par metodēm un paņēmieniem roku sīkas motorikas attīstīšanai pareiza satvēriena veidošanā. Darba praktiskajā daļā tika veikts praktiskais pētījum…
Channeled scaffolds implanted in adult rat brain.
2012
Scaffolds with aligned channels based on acrylate copolymers, which had previously demonstrated good com- patibility with neural progenitor cells were studied as coloniz- able structures both in vitro with neural progenitor cells and in vivo, implanted without cells in two different locations, in the cortical plate of adult rat brains and close to the subven- tricular zone. In vitro, neuroprogenitors colonize the scaffold and differentiate into neurons and glia within its channels. When implanted in vivo immunohistochemical analysis by confocal microscopy for neural and endothelial cells markers demonstrated that the scaffolds maintained continuity with the surrounding neural tissue and wer…
In vitro validation of biomedical polyester-based scaffolds: Poly(lactide-co-glycolide) as model-case
2018
[EN] Monitoring and understanding the in vitro behaviour of polyester based scaffolds both comprising the study of the hydrolytic degradation and the cell seeding viability is essential to ensure the desired functionality, according to a given biomedical purpose. As a model case to compare the performance of techniques to monitor the in vitro behaviour, poly(lactide-co-glycolide) (PLGA) scaffolds were chosen. The in vitro hydrolytic degradation of PLGA scaffolds was carried out in water and phosphate buffered saline (PBS). The evolution of the mass loss, the molar mass, the thermal properties and the surface morphology were monitored. The hydrolytic degradation media was correspondingly eva…
THE OPTIMAL SCALING OF A LINEAR RELUCTANCE MOTOR BY FIELD COMPUTATION
1995
The work aims at investigating the law of miniaturization of a linear reluctance motor by expressing the ratio of force to mass as a function of bar position in per unit, for different scale factors. Corresponding to the same factors, inductance is also computed. Finally the ratio of the bar length to external diameter is changed and the analysis is accordingly repeated.
Extension and Tuning of Virtual Synchronous Machine to Avoid Oscillatory Instability in Isolated Power Networks
2020
The risk of oscillatory instability introduced by virtual synchronous machines (VSM) control in isolated power networks is investigated. The considered control is a common scheme widely studied in literature, in several configurations and for different case studies. The impact of the VSM control on the system stability is examined for the existing power network of a Mediterranean island. The VSM control is implemented within the power converters interfacing the energy storage systems (ESS) installed in the network. Simulations and analysis show the occurrence of oscillatory instability in the system, with the ESS-VSM and the synchronous machines of the network progressively swinging against…
MOTOR COORDINATION DIFFICULTIES IN CHILDREN WITH LEARNING DISABILITIES
2016
Nowadays increasing the number of children with learning disabilities in comprehensive schools of Latvia, so it is necessary preventive measures during schooltime. One of the support measures are short movement activity in academic lessons. The aim of article is theoretical analyze the correlations between motor coordination difficulties and the child's academic achievement and find out primary school teachers' views on possible support for children with learning disabilities. Main findings – development of motor coordination in children of primary schools is effective when using short movement breaks in classroom. Research methods: analysis of scientific and methodological literature, a su…
Vibration effect on ball score test in international vs. national level table tennis
2018
In table tennis, motor skills are crucial for discriminating player level. However, there is a dearth of studies exploring the impact of a vibrational stimulus on performance. Thirty-four male players (age 25 +/- 2 years ; body mass index, BMI 23.4 +/- 1.2 kg.m(-2)) participated in the study. Seventeen played at international level (IL), while the remaining 17 played at national level (NL). The participants underwent a ball-handling test, the ball score, before (PRE) and after (POST) a vibrational stimulus. Intra-class correlation (ICC) for the ball score result showed good reliability (ICC 0.87 for IL and 0.80 for NL). Repeated measures ANOVA showed differences between groups for ball scor…