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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Energetski efikasno digitalno upravljanje sinhronim motorom sa stalnim magnetima pri velikim brzinama obrtanja / Energy Efficient Digital Control of Permanent Magnet Synchronous Motor in High Speed Region

Gecić Marko 02 February 2017 (has links)
<p>U ovoj doktorskoj disertaciji optimizacioni algoritam zasnovan na roju čestica primenjen je na problem optimalnog upravljanja pogonom sa sinhronim motorom sa stalnim magnetima pri velikim brzinama obrtanja. Kako bi se smaljili ukupni kontrolabilni gubici električne energije i povećala efikasnost generisan je optimalni referentni vektor statorske struje za širok opseg brzina i za različita opterećenja. Prilikom optimizacije uvažena su naponska i strujna ograničenja invertora, kao i promena induktivnosti statora. Sačuvani generisani vektor struje statora se koristi prilikom upravljanja pogonom u realnom vremenu, a predloženi algoritam se poredi sa standarnim upravljanjem.</p> / <p>In this PhD thesis, a particle swarm optimization algorithm was applied to the problems of optimal control of high speed permanent magnet motor drives. In order to minimize the total controllable electrical losses and to increase the efficiency, the optimum current vector references are calculated offline for the wide speed range and for different load conditions. The voltage and current limits of the drive system and the variation of stator inductances are all included in the optimization method. The stored optimal current vector references are used during the real time control and the proposed algorithm is compared with the conventional control algorithm.</p>
2

Model detekcije benzena, toluena, etilbenzena i ksilena u izduvnim gasovima motornih vozila primenom gasne hromatografije u funkciji procene zagađenja ambijentalnog vazduha / Detection model of benzene, toluene, ethylbenzene and xylene in exhaust gases of motor vehicles by using gas chromatography in evaluating of ambient air pollution

Adamović Dragan 09 January 2015 (has links)
<p>U okviru doktorske disertacije opisane su jedinstvene fiziĉko-hemijske karakteristike<br />grupe supstanci benzena, toluena, etilbenzena i ksilena koje pripadaju istraživanjima<br />najnovijeg trenda nauĉne javnosti. Posebno su opisane perzistencija i<br />pseudoperzistencija, transport, distribucija i negativan i toksiĉan uticaj na zdravlje<br />ĉoveka i životnu sredinu. Sprovedena su eksperimentalna istraživanja zavisnosti<br />koncentracionih nivoa BTEX jedinjenja u izduvnim gasovima i operativnih parametara<br />eksperimentalnog motora SUS. Na osnovu dobijenih rezultata eksperimentalnih<br />istraživanja definisan je emisioni model BTEX jedinjenja simulacijom kretanja<br />putniĉkog automobila Fiat Punto Classic u skladu sa NEDC ciklusom koji na<br />odgovarajući naĉin reprezentuje standarde uslove vožnje u evropskim gradovima.</p> / <p>In this thesis, the unique physicochemical characteristics of a group of substances<br />consisting of benzene, toluene, ethylbenzene and xylene have been described.<br />Special emphasis has been placed on their characteristics of persistence and pseudopersistence,<br />transport, distribution and the negative and toxic influence on human<br />health and the environment. The experimental research of the interdependence of the<br />concentration levels of BTEX compounds in the exhaust gases and the operational<br />parameters of the experimental IC engine has been conducted. Based on the<br />experimental research results, the emission model of the BTEX compounds has been<br />defined by a simulation of movement of a Fiat Punto Classic passenger car in<br />accordance with the NEDC cycle, which appropriately represents the standard driving<br />conditions in European cities. Research conducted within the thesis represents the<br />newest trend of investigation in the scientific world.</p>
3

SUBSTRATI NEUROSTRUTTURALI E NEUROFUNZIONALI DELLA DISFUNZIONE ESECUTIVA NELLA MALATTIA DI PARKINSON: IL RUOLO DELLA LATERALIZZAZIONE DEI SINTOMI MOTORI E DELLA RISERVA COGNITIVA / NEUROSTRUCTURAL AND NEUROFUNCTIONAL SUBSTRATES OF EXECUTIVE DYSFUNCTION IN PARKISON'S DISEASE: THE ROLE OF MOTOR LATERALIZATION AND COGNITIVE RESERVE / NEUROSTRUCTURAL AND NEUROFUNCTIONAL SUBSTRATES OF EXECUTIVE DYSFUNCTION IN PARKINSON’S DISEASE: THE ROLE OF MOTOR LATERALIZATION AND COGNITIVE RESERVE

DI TELLA, SONIA 06 April 2020 (has links)
La disconnessione frontostriatale è considerata il correlato neurale della disfunzione esecutiva nei pazienti con malattia di Parkinson (MP), una patologia neurodegenerativa che si presenta nella fase iniziale come una sindrome clinica asimmetrica con sintomi predominanti nel lato destro o sinistro associati alla perdita neuronale nella sostanza grigia profonda dell'emisfero cerebrale controlaterale. Nella tesi, è stato indagato un particolare aspetto della disfunzione esecutiva nella MP espressa quando è richiesto di selezionare le parole nel contesto di alternative in competizione, cercando differenze in relazione all'insorgenza clinica dei sintomi motori. A livello neurostrutturale, sono state esplorate le alterazioni della sostanza grigia e bianca nelle sottopopolazioni di MP, verificando se la capacità di selezionare le parole è associata ad indici di integrità della materia sostanza grigia e bianca nelle sottopopolazioni di PD. Infine, a livello neurofunzionale, è stato esplorato se la connettività delle regioni cerebrali associate alla disfunzione esecutiva in MP è modulata dalla riserva cognitiva, un fattore di efficienza cognitiva dovuto ad esperienze di vita cognitivamente stimolanti che possono contribuire alla resilienza nel fronteggiare al meglio la neurodegenerazione. Le evidenze raccolte indicano che la lateralità di insorgenza dei sintomi motori e la riserva cognitiva dovrebbero essere prese in considerazione nella valutazione delle funzioni cognitive nei pazienti con MP. / Frontostriatal disconnection is considered the neural correlate of executive dysfunction in patients with Parkinson’s disease (PD), a neurodegenerative pathology that exhibits at the initial phase as an asymmetric clinical syndrome with right or left sided predominant symptoms associated with neuronal loss in the deep grey matter of the contralateral cerebral hemisphere. In the current thesis, it was investigated a particular aspect of the executive dysfunction in PD expressed when it is required to select words in the context of competing alternatives, looking for differences according to the clinical onset of motor symptoms. At the neurostructural level, grey and white matter alterations were explored in PD subpopulations, testing if the ability to select words is associated with indices of grey and white matter integrity in PD subpopulations. Finally, at the neurofunctional level, it was explored if the connectivity of brain regions associated with the executive dysfunction in PD is modulated by the cognitive reserve, a factor of cognitive efficiency due to lifelong experiences that may contribute to the resilience against neurodegeneration. The evidence collected indicates that laterality of clinical motor symptom onset and cognitive reserve should be taken into account in the assessment of cognitive functions in patients with PD.

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