Search results for " MOTOR"
showing 10 items of 1044 documents
Analysis of Stray Flux Spectral Components in Induction Machines under Rotor Bar Breakages at Various Locations
2018
Induction machines under rotor electrical faults have been subjected to intensive research over the years. It is not only the nature of the fault that makes it important to study, but also the differences observed regarding this fault's effect on the motor's conditions. One of these conditions is the rotor bar breakages at non adjacent positions, which has drawn the attention of researchers due to the false negative diagnostic alarms that may be caused. In this paper, a novel approach is presented aiming to reliably detect this type of fault condition. The proposed method is based on the analysis of specific subcomponents of the stray flux over time. The analysis is implemented on an indust…
Pirkstu rotaļu izmantošana 3-4 gadīgu bērnu runas prasmju veicināšanā
2019
Kvalifikācijas darba tēma "Pirkstu rotaļu izmantošana 3 - 4 gadīgu bērnu runas prasmju veicināšanā" Darba autore "Jevgeņija Kosteņukova" Zinatniska vaditāja Ilze Vilka
Novel silicon microparticles to improve sunlight stability of raw polypropylene
2015
Oxidation of polyolefins by ultraviolet/visible irradiation is a significant limitation for their use in several technological applications. The use of high-tech additives such as silicon microparticles becomes a compositing strategy that can improve the performance of these materials at long-term service conditions. Silicon particles were added to non-additivated raw polypropylene (PP) prepared by hot melt extrusion and subjected to accelerated sunlight irradiation tests. The stability of thermal properties, mechanical performance and thermal decomposition behaviour of composites was evaluated by differential scanning calorimetry, dynamic mechanical thermal analysis and thermogravimetry. T…
Roku sīkās motorikas pilnveide rotaļās un vingrinājumos fonētiski fonemātisko traucējumu novēršanai vecākā pirmsskolas vecuma bērniem
2019
Darba autors: Ilva Līce Darba zinātniskais vadītājs: Mg. paed. Zane Skribanovska Darba nosaukums: Roku sīkās motorikas pilnveide rotaļās un vingrinājumos fonētiski fonemātisko traucējumu novēršanai vecākā pirmsskolas vecuma bērniem. Pētījuma mērķis: Teorētiski izzināt un praktiskā darbībā atlasīt, pielietot, izvērtēt rotaļas un vingrinājumus roku sīkās motorikas pilnveidei fonētiski fonemātisko traucējumu novēršanai. Darbā izvirzītā hipotēze: Fonētiski fonemātisko traucējumu koriģējoši attīstošā darbība noritēs sekmīgāk, ja logopēds: •pārbaudīs un analizēs katra bērna skaņu izrunas traucējumus; •atbilstoši bērna vajadzībām atlasīs un pielietos, koriģējoši attīstošajā darbībā, rotaļas un vin…
Vidējā pirmsskolas vecumposma bērnu runas attīstība rokdarbos
2022
Šī bakalaura darba mērķis ir apkopot un analizēt informāciju no dažādu autoru teorijām par bērnu runas attīstību saistībā ar rokdarbiem pirmsskolas vidējā vecumposmā un pētīt, kā tā atspoguļojas praksē, strādājot ar bērniem. Darba autore ir Latvijas Universitātes profesionālās bakalaura studiju programmas “Pirmsskolas un sākumskolas skolotājs” studente Līga Zīraka. Darba zinātniskā vadītāja ir Latvijas Universitātes docente Dr. paed. Ingūna Lāce. Darba nosaukums: Vidējā pirmsskolas vecumposma bērnu runas attīstība rokdarbos. Teorētiskajā daļā tika apkopoti un analizēti gan latviešu, gan ārzemju literatūras avoti, kopā – 34. Tika apskatīti tādu autoru darbi kā I. Hadaņonokas, L. Hadaņonokas,…
A teacher-led motor programme to enhance pre-literacy and motor skills in kindergarten children
2020
Structured motor tasks may affect cognitive development by creating a cognitively challenging “enriched environment’, giving opportunity for social cooperation, increasing the joy to learn through play, improving the sense of mastery and competence. The study investigated the association between motor and cognitive exercises, through a teacher-led programme, to provide kindergarten children with the skills necessary for school literacy. Using a cluster-randomized trial design with an intervention group (N = 110) and a control group (N = 64), we examined the effects of a 3-month teacher-led motor programme enriched by executive function tasks. In the intervention group, significant gains wer…
WAVES PROPAGATION AND LIQUID ALUMINUM PARTICLE INJECTION IN SOLID ROCKET MOTORS
2013
A method to determine the injection of aluminium particles from the solid propellant burning surface to the core of the chamber in the presence of an acoustic wave field is developed and aluminum-droplet effects on propagation of acoustic waves in the flow of a solid rocket motor are analysed. Changes of the multiphase flow compressibility are calculated by taking into account both the translational and the pulsational motions of the aluminum droplets in consequence of the acoustic waves.
A statistical design of experiments for optimizing the MALDI-TOF-MS sample preparation of polymers. An application in the assessment of the thermo-me…
2011
[EN] The sample preparation procedure for MALDI-TOF MS of polymers is addressed in this study by the application of a statistical Design of Experiments (DoE). Industrial poly (ethylene terephthalate) (PET) was chosen as model polymer. Different experimental settings (levels) for matrixes, analyte/matrix proportions and concentrations of cationization agent were considered. The quality parameters used for the analysis were signal-to-noise ratio and resolution. A closer inspection of the statistical results provided the study not only with the best combination of factors for the MALDI sample preparation, but also with a better understanding of the influence of the different factors, individua…
Triblock SEBS/DVB crosslinked and sulfonated membranes: Fuel cell performance and conductivity
2021
[EN] A set of styrene-ethylene-butylene-styrene triblock copolymer (SEBS) membranes with 10 or 25 wt.% divinyl-benzene (DVB) as a crosslinking agent were prepared and validated. Physicochemical characterization revealed suitable hydrolytic and thermal stability of photo-crosslinked membranes containing 25%wt. DVB and post-sulfonated. These compositions were evaluated in H2/O2 single cells, and electrical and proton conductivities were furtherly assessed. The membranes with the milder post-sulfonation showed greater proton conductivity than those with excessive sulfonation. In terms of electrical conductivity, a universal power law was applied, and the values obtained were low enough for bei…
Effect of the dissolution time into an acid hydrolytic solvent to tailor electrospun nanofibrous polycaprolactone scaffolds
2017
[EN] The hydrolysis of the polycaprolactone (PCL) as a function of the dissolution time in a formic/acetic acid mixture was considered as a method for tailoring the morphology of nanofibrous PCL scaffolds. Hence the aim of this research was to establish a correlation between the dissolution time of the polymer in the acid solvent with the physicochemical properties of the electrospun nanofibrous scaffolds and their further service life behaviour. The physico-chemical properties of the scaffolds were assessed in terms of fibre morphology molar mass and thermal behaviour. A reduction of the molar mass and the lamellar thickness as well as an increase of the crystallinity degree were observed …