• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 6
  • 5
  • 1
  • 1
  • Tagged with
  • 13
  • 13
  • 5
  • 4
  • 4
  • 4
  • 4
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 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

Radiotherapy Cancer Treatment: Investigating Real-Time Position and Dose Control, the Sensor-Delayed Plant Output Estimation Problem, and the Nonovershooting Step Response Problem

Stewart, James 13 December 2006 (has links)
For over a century, physicians have prescribed x-ray radiation to destroy or impede the growth of cancerous tumours. Modern radiation therapy machines shape the radiation beam to balance the competing goals of maximizing irradiation of cancerous tissue and minimizing irradiation of healthy tissue, an objective complicated by tumour motion during the treatment and errors positioning the patient to align the tumour with the radiation beam. Recent medical imaging advances have motivated interest in using feedback during radiation therapy to track the tumour in real time and mitigate these complications. This thesis investigates how real-time feedback control can be used to track the tumour and focus the radiation beam tightly around the tumour. Improving on these results, a feedback control system is proposed for intensity modulated radiation therapy which allows a non-uniform radiation dose to be applied to the tumour. Motivated by the results of the proposed control systems, this thesis also examines two theoretical control problems: estimating the output of an unknown system when a sensor delay prevents its direct measurement, and designing a controller to provide an arbitrarily fast nonovershooting step response.
2

Radiotherapy Cancer Treatment: Investigating Real-Time Position and Dose Control, the Sensor-Delayed Plant Output Estimation Problem, and the Nonovershooting Step Response Problem

Stewart, James 13 December 2006 (has links)
For over a century, physicians have prescribed x-ray radiation to destroy or impede the growth of cancerous tumours. Modern radiation therapy machines shape the radiation beam to balance the competing goals of maximizing irradiation of cancerous tissue and minimizing irradiation of healthy tissue, an objective complicated by tumour motion during the treatment and errors positioning the patient to align the tumour with the radiation beam. Recent medical imaging advances have motivated interest in using feedback during radiation therapy to track the tumour in real time and mitigate these complications. This thesis investigates how real-time feedback control can be used to track the tumour and focus the radiation beam tightly around the tumour. Improving on these results, a feedback control system is proposed for intensity modulated radiation therapy which allows a non-uniform radiation dose to be applied to the tumour. Motivated by the results of the proposed control systems, this thesis also examines two theoretical control problems: estimating the output of an unknown system when a sensor delay prevents its direct measurement, and designing a controller to provide an arbitrarily fast nonovershooting step response.
3

Modeling and testing of line start permanent magnet motors

Modeer, Tomas January 2007 (has links)
<p>This licentiate thesis describes the modeling and measurements performed with the aim of developing design guidelines for Line Start Permanent Magnet Synchronous Motors, LSPMSMs. LSPMSMs can offer higher efficiency than standard induction motors used in the industry today, especially for small motor sizes. The increase in efficiency results in lower environmental impact and reduced electricity cost. The LSPMSM has, however, several drawbacks, among the most important is the reduced starting capability compared to induction motors. Furthermore, the rotor construction is complex and the added cost of magnet material makes the LSPMSM a comparably expensive motor type. The design of a LSPMSM is a trade-off between starting capability and steady state performance. The thesis discusses these trade-offs and the models that can be used as a basis for design and optimization. The models make use of different motor parameters, and a number of measurement methods for measuring these parameters are described and compared. Among these is a step response adapted measurement method that provides most of the parameters of interest. The development and setup of a brake bench for measuring both start-up and steady state performance is presented. Furthermore the start-up behavior and steady-state performance is calculated using measured parameters. The calculated performance is compared to measured performance and found to correlate well for nominal operating conditions. Thus, design guidelines can be based on the models proposed.</p>
4

Experimentální pracoviště řízeného pohonu s vysokou dynamikou / Experimental workplace of controlled drive with high dynamics

Rozkošný, Miroslav January 2013 (has links)
My diploma thesis deals with the basic principle of the frequency inverter and his construnction. In the next section are analyze the basic properties and characteristics of the using equipment. The main part of this thesis is to investigate the dynamic properties of asynchronous electric motor controlled by a frequency inverter using STARTER. The results of experiments are compared and analyzed.
5

Modeling and testing of line start permanent magnet motors

Modeer, Tomas January 2007 (has links)
This licentiate thesis describes the modeling and measurements performed with the aim of developing design guidelines for Line Start Permanent Magnet Synchronous Motors, LSPMSMs. LSPMSMs can offer higher efficiency than standard induction motors used in the industry today, especially for small motor sizes. The increase in efficiency results in lower environmental impact and reduced electricity cost. The LSPMSM has, however, several drawbacks, among the most important is the reduced starting capability compared to induction motors. Furthermore, the rotor construction is complex and the added cost of magnet material makes the LSPMSM a comparably expensive motor type. The design of a LSPMSM is a trade-off between starting capability and steady state performance. The thesis discusses these trade-offs and the models that can be used as a basis for design and optimization. The models make use of different motor parameters, and a number of measurement methods for measuring these parameters are described and compared. Among these is a step response adapted measurement method that provides most of the parameters of interest. The development and setup of a brake bench for measuring both start-up and steady state performance is presented. Furthermore the start-up behavior and steady-state performance is calculated using measured parameters. The calculated performance is compared to measured performance and found to correlate well for nominal operating conditions. Thus, design guidelines can be based on the models proposed. / QC 20101112
6

Modelagem de uma planta didática multivariável e não linear

Thomas, Wallas Gusmão 07 May 2010 (has links)
Made available in DSpace on 2016-12-23T14:07:26Z (GMT). No. of bitstreams: 1 Dissertacao_WALLAS_Final.pdf: 2098098 bytes, checksum: fd85081c515eea7e1921beb926a980cc (MD5) Previous issue date: 2010-05-07 / O objetivo deste trabalho é mostrar o desenvolvimento do modelo de uma planta didática não linear e multivariável usando a resposta ao degrau. Esta planta didática é do curso técnico de automação industrial do IFES SERRA (ES). A partir das equações físicas do processo são desenvolvidas as relações entre as variáveis controladas e as variáveis manipuladas em regime permanente para qualquer ponto de operação. Utilizando a resposta ao degrau, de acordo com sua amplitude, são mapeadas as constantes de tempo do processo. O atraso do modelo é encontrado utilizando os mínimos quadrados. Por fim é desenvolvido um simulador a fim de comparar a resposta no tempo da planta real com a do modelo proposto. / The objective of this dissertation is to show the development of one nonlinear pilot plant model and multivariable using the step response. The pilot plant belongs to the course of industrial process control of IFES - SERRA (ES). From the physical equations of the process, are developed relationships of controlled variables in steady state at any point of operation. Using the step response, are mapped onto the time constants of the process according to the changes of the manipulated variables. The delay model is found using the least squares and step response. Finally we developed a simulator to compare the time response of the real plant with the proposed model.
7

Tekniikan ylioppilaiden valmistumiseen johtavien opintopolkujen mallintaminen — perusteena lukiossa ja opiskelun alkuvaiheessa saavutettu opintomenestys

Honkanen, S. (Seppo) 18 December 2010 (has links)
Abstract In the present research of engineering studies in the Department of Process and Environmental Engineering in the University of Oulu the graduation processes of eight various groups of students were documented and analyzed. For the validation of the data triangulation method was availed of. The accumulation of study attainments was calculated and, using the measured data, the graduation time models were created. A new method of modeling a non-linear study process by using a Matlab step response model was developed. The model is exact in the essential area of operation and can be used in any educational organization which considers following the process of graduation important. In this research study attainments were examined and explained with the help of self-regulation test analyses. The test used in this research is based on a shortened version of Guglielmino’s Self Directed Learning Readiness test. It measures the student’s capability for autonomous learning. A connection between good success in studies and observed self-directive learning was noticed as early as during the second academic year. The engineering study attainments were also compared to the study success in the upper secondary school. The results show that the students with satisfactory learning results in the upper secondary school did better than expected in their university studies. Instead, the students with better success in the upper secondary school than the group mentioned underachieved in their university studies. The students whose success was better than average during the first academic year were also better during the following years. Examining the study attainments of the eight elementary courses during the three years of studies showed that about 46 per cent of students passed the elementary courses in proper time. One year after the elementary courses had been given, 73 per cent of the students had passed them. / Tiivistelmä Tekniikan ylioppilaiden opiskelututkimuksessa käytettiin tutkimusmenetelmänä triangulaatiota. Työssä analysoitiin kahdeksan eri vuosikurssin opintosuoritusten perusteella Oulun yliopiston Prosessi- ja ympäristötekniikan osaston opiskelijoiden valmistumisprosessia. Opintosuoritusten avulla laskettiin eri vuosikurssien opintoviiveet ja saatujen mittaustietojen avulla tehtiin valmistumisaikamallit. Tutkimuksessa löydettiin uusi tapa mallintaa epälineaarista opiskeluprosessia askelvastemallilla. Menetelmän avulla saatu suoriutumismalli on todellisiin mittaustuloksiin verrattuna luotettava keskeisellä toiminta-alueella kolmesta seitsemään vuotta, kun tavoitteena on, että aloittaneista valmistuu 50 % kuudessa vuodessa. Työssä tutkittiin opintomenestystä itseohjautuvuusvalmiutta selvittävien testistöjen avulla. Tutkimuksessa käytetty testi perustuu Koron (1993) laatimaan versioon. Se on lyhennetty Guglielminon (1977) luomasta testistä Self Directed Learning Readiness, joka mittaa opiskelijan valmiutta itseohjattuun opiskeluun. Tutkimuksessa käytetyssä SDLR-testissä yhteen laskettujen pisteiden vaihteluväli on 37–185. Työssä käytetyn itseohjautuvuusanalyysin avulla testattiin opiskelijoiden valmiutta itsenäiseen ja pitkäjänteiseen opiskeluun opinto-ohjelman mukaisesti. Löydettiin yhteys keskimääräistä paremman opiskelumenestyksen ja keskimääräistä kehittyneemmän itseohjautuvuusvalmiuden välillä. Opiskelua tutkittiin lukiomenestyksen perusteella. Voitiin havaita, että tyydyttävästi lukiossa menestyneet pärjäsivät odotettua paremmin yliopisto-opinnoissaan. Sen sijaan lukiossa hyvin menestyneet alisuoriutuivat odotettua useammin opinnoissaan. Ensimmäisenä opiskeluvuonna keskimääräistä paremmin menestyneet opiskelijat selvisivät jatkossakin paremmin. Tämän havainnon perusteella voidaan väittää, että ensimmäisen vuoden opintomenestyksellä on selvä yhteys tulevien vuosien opintomenestykseen: huono opintomenestys ensimmäisenä vuotena johti sekä vuonna 2005 että 2004 aloittaneiden opiskelijoiden ryhmissä keskimäärin noin 26 % alempaan opintoviikkokertymään kolmen vuoden aikana verrattuna hyvin opiskelussa ensimmäisenä vuonna menestyneisiin ryhmiin. Opintosuorituksia tutkittiin kolmen ensimmäisen opiskeluvuoden aikana olleiden kahdeksan peruskurssin osalta. Havaittiin, että keskimäärin 46 % opiskelijoista suoritti peruskurssit ajallaan. Vuoden kuluttua peruskurssien päättymisestä keskimäärin 73 % opiskelijoista oli suorittanut ne.
8

Laboratorní úloha s regulací teploty / Laboratory device with temperature control

Telecký, Jakub January 2020 (has links)
This work deals with regulation and procedures that can be used for this. The theoretical part therefore presents the basic concepts of automation and controllers. The main part is the practical part. The purchased system consists of a regulated system, which must be set up correctly. Using system identification and known procedures, sample examples of how to best set the controller are compiled. The result is a sample laboratory task that automation students can try and gain experience with methods of setting up the controller.
9

Matematický model kotle na biomasu pro účely řízení / Mathematical Model of Biomass Boiler for Control Purposes

Máša, Vítězslav January 2010 (has links)
he thesis focuses on building of dynamic mathematical model of biomass boiler as a controlled system and the use of this model in practise. At the first part of the thesis the area of energy production using biomass is introduced and the current development at the area of the automatic control of biomass boilers with medium energy output (in units of MW) is described. Although the main topic of the thesis is the construction of model of biomass boiler for control purposes, thesis deals with technology of boilers and principles of its inner processes as well. Creation of the model comes out not only from these important findings, but also from experimental data collected during measurements in real operation. Heat and mass balance calculations were made according to these data and they serve to precise static properties of experimental unit for biomass combustion. Central part of the thesis presents development of the final model that resulted from balance calculations and from step responses of the system obtained by measuring. Built dynamic model is compared with experimental data through simulations in Simulink and verified. At the next part the model of controlled system is completed with control system and closed-loop control circuit is validated and verified by simulation. Then the design of new controller configuration, which improves the quality of control considerably, is presented. At the final part of the thesis, possibilities of other use of the model of boiler are given, both in control theory and in industrial practice.
10

Innovative non-destructive methodology for energy diagnosis of building envelope / Méthodologies innovantes non destructives appliquées au diagnostic énergétique de l'enveloppe du bâtiment

Yang, Yingying 18 December 2017 (has links)
Le secteur du bâtiment représente 35% des la consommations énergétiques dans les pays membres de l’agence international de l’énergie en 2010 et 39,8% aux Etats-Unis en 2015. Plus de 50% de cette consommation a été utilisée pour la production de chaleur et de froid. Néanmoins cette consommation peut être réduite par l'amélioration la performance énergétique du bâtiment. La performance thermique de l'enveloppe du bâtiment joue un rôle primordial. Par conséquent, le diagnostic thermique de l'enveloppe du bâtiment est nécessaire pour, par exemple, la réception de nouvelles constructions, l'amélioration de la performance énergétique des anciens bâtiments, ainsi que la vente et la location des logements. Pourtant, il existe très peu de méthodes quantitatives pour la caractérisation des parois épaisses. L'objectif de cette étude est d'explorer des méthodes quantitatives innovantes de diagnostic thermique de l'enveloppe du bâtiment. Des mesures expérimentales ont été réalisées en laboratoire (à l’IFSTTAR à Nantes) et in situ (à l’IUT de Bordeaux). Différents capteurs et méthodes d'instrumentation ont été étudiés pour mesurer la densité de flux et la température de surfaces des parois, afin de procurer des recommandations pour le choix des capteurs ainsi que des protocoles de traitement de données. A partir des données mesurées (température et densité de flux des surfaces de l'enveloppe), trois approches numériques ont été proposées pour estimer des paramètres thermiques des parois multicouches épaisses : par méthode inverse, par réponse à un échelon et par réponse impulsionnelle. En outre, une méthode innovante non-destructive utilisant la rayonnement térahertz a été étudiée. Les mesures ont été effectuées au sein du laboratoire I2M. Cette méthode permet de caractériser le coefficient d'absorption des matériaux constructifs ordinaires comme isolation, plâtre, béton, bois… Elle pourrait postérieurement être combinée avec une méthode thermique pour apporter des informations complémentaires. / Buildings represent a large share in terms of energy consumption, such as 35% in the member countries of IEA (2010) and 39.8% in U.S. (2015). Climate controlling (space heating and space cooling) occupies more than half of the consumption. While this consumption can be reduced by improving the building energy efficiency, in which the thermal performance of building envelope plays a critical role. Therefore, the thermal diagnosis of building envelope is of great important, for example, in the case of new building accreditation, retrofitting energy efficiency of old building and the building resale and renting. However, very few diagnostic methods exist for the characterization of thick walls. The present measurement standards that based on steady state heat transfer regime need a long time (several days). The classical transient technologies, such as flash method, are difficult to implement on the walls because of the large thickness of walls and the complex conditions in situ. This thesis aims to explore innovative methodologies for thermal quantitative diagnosis of building envelope. Two experimental cases were carried out: one is in laboratory (IFSTTAR, Nantes) and the other is in situ (IUT, Bordeaux). Different sensors and instruments were studied to measure the wall heat flux and surface temperature, and provided some guidelines for the choice of sensors and data processing protocols as well. Using these measured data, three estimation approaches were proposed to estimate the thermal parameters of the multilayer thick wall: pulse response curve method, step response curve method and inverse method, which can be applied for different diagnostic situations. In addition, an innovative NDE (non-destructive evaluation) method using terahertz (THz) radiation was also investigated. Measurements were carried out in I2M laboratory to characterize the absorption coefficient of standard building materials (insulation, plaster, concrete, wood ...). This THz method can be combined with a previous thermal method to provide some complementary information.

Page generated in 0.1627 seconds