• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 557
  • 236
  • 181
  • 106
  • 75
  • 41
  • 32
  • 14
  • 12
  • 10
  • 7
  • 5
  • 5
  • 4
  • 4
  • Tagged with
  • 1450
  • 394
  • 296
  • 210
  • 170
  • 164
  • 152
  • 149
  • 140
  • 136
  • 120
  • 115
  • 109
  • 96
  • 95
  • 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.
11

Improved direct torque control and robust adaptive control of induction motor drives

Wong, Wallace Shung Hui January 2003 (has links)
No description available.
12

Pole-assignment high order controllers and applications to adaptive control with on-line supervision

Mustafa, Mohd Marzuki bin January 1989 (has links)
No description available.
13

Fractional Order Controller for Quadcopter Subjected to Ground Effect

Mirghasemi, Seyed Alireza 28 May 2019 (has links)
Although the concept of fractional calculus was known for centuries, it was not considered in engineering due to the lack of implementation tools and acceptable performance of integer order models and control. However, recently, engineers and researchers started to investigate the potentially high performance of fractional calculus in various fields among which are acoustics, conservation of mass, diffusion equation and specifically in this thesis control theory. The intention of this thesis is to analyze the relative performance of fractional versus integer order PID controller for a quadcopter. Initially, the dynamics of the quadcopter is presented with additional consideration of the ground effect and torque saturation. Then, are introduced the concept of fractional calculus and the mathematical tools to be used for modeling fractional order controller. Finally, the performance of the fractional order controller is evaluated by comparing it to an integer order controller.
14

Analyse des mécanismes de pollution d’une alimentation à découpage sur des fonctions analogiques embarquées sur un même « Système sur Puce » et développement de techniques de minimisation du bruit de l’alimentation à découpage / Impact analysis of the buck converter noise on sensitive analog IPs in a SoC

Feltrin, Eric 10 April 2019 (has links)
Le marché des microcontrôleurs est en pleine mutation et devrait croitre propulsé par le développement de l’Internet des objets. La puissance de calcul, la connectivité, les performances des périphériques et l’efficacité énergétique sont les facteurs clés de ce développement. Le module de gestion de l’alimentation est entièrement intégré au sein même du microcontrôleur lui permettant de fonctionner avec uniquement quelques composants passifs. Ce module doit assurer le maintien de la tension d’alimentation indépendamment de la consommation du microcontrôleur qui augmente avec la puissance de calcul. L’architecture choisie doit également optimiser le rendement selon la consommation du microcontrôleur sans impacter le fonctionnement de blocs sensibles. L’intégration de l’étage de puissance d’une alimentation à découpage engendre du bruit de commutation ayant un impact sur les fonctions analogiques du circuit. L’objectif de ce travail est l’analyse de la génération du bruit par l’étage de puissance et sa propagation au sein du circuit complexe. Le modèle de génération du bruit est constitué de circuits RLC équivalents. Les expressions des R, L et du C sont exprimées dans chaque état de l’étage de puissance en fonction des composants parasites du système. Ces modèles permettent de comprendre le mécanisme de génération du bruit et de donner une estimation de l’amplitude et de la fréquence des résonances. L’ensemble du système c’est-à-dire le circuit, le boitier et la carte électroniques, est modélisé pour extraire les chemins de propagation entre l’alimentation à découpage et les cellules sensibles du système. Ces modèles sont vérifiés en mesurant un circuit de test. Finalement trois solutions sont proposées pour réduire l’impact du bruit de l’alimentation à découpage : deux changements dans l’architecture de l’étage de puissance pour réduire la génération du bruit et une modification des interconnexions globales du circuit pour améliorer l’isolation entre les différentes parties du système. Cette thèse présente une méthodologie originale pour construire un modèle au niveau système de la génération et de la propagation du bruit de commutation. Les connaissances acquises ont été vérifiées expérimentalement et appuyées par la conception d’un démonstrateur (qui doit être testé). / The micro-controller market is undergoing changes and is expected to grow quickly promoted by the Internet-of-Things (IoT) development. Calculation capability, connectivity, analog performances and power efficiency are key enablers. Power management unit is co-integrated with the micro-controller so that only few off-chip passive components are necessary. The embedded power management unit must deliver the micro-controller input voltage along with the power demand which increases with the computation capability. The chosen architecture has to optimize the efficiency in high and low power mode but without impacting analog performance of sensitive IPs (Intellectual Property). The active part of an inductive buck converter is integrated but some switching noise is observed that severely impact analog IPs. The objective of this work is the analysis of the noise generation from the power stage and its propagation in the System-on-Chip (SoC). The generation model is constituted of a RLC equivalent circuits in each state of the power stage. The R, L and C expressions are detailed depending on physical parasitic components. These models permit to understand noise mechanisms and to give an estimation of the noise amplitude and frequency resonance. The models show the degrees of freedom to manage the noise signature. The whole system, i.e. the electronic board, the package and the chip, is modeled to extract the system-level propagation path between the buck converter and sensitive IPs. These models are verified by measurement on a test vehicle. Finally three solutions are presented to reduce the buck converter noise impact: two changes in the power stage architecture to reduce noise generation and one modification of the top routing of the power delivery network to improve isolation between parts of the circuit regarding noise susceptibility. The thesis contributes an original methodology to build the missing models at system-level regarding noise generation and propagation from the switching power supply. Knowledge has been acquired, experimentally verified and supported by the design of a demonstrator (to be tested).
15

Projektverksamhetens"early-warner"- en jämförande studie om projektcontrollerns funktion / The early-warner of the project activity : a comparable study about the funktion of the project controller

Carlsson, Cecilia, Wulff, Renée January 2003 (has links)
<p>Background: The project controller is a function witch evolved due to the strong gaining ground of project operation. Why the area of the project controller is interesting to study is explained by the fact that increasing knowledge of this function is important in order to make project operation work well. The fact that opinions in this field disagree, further increases the interest of the field. In order to study the function of the project controller three companies have been singled out. They are IFS, Intentia and Saab Bofors Dynamics. The selection is based upon them being knowledge based companies with project intense operation. </p><p>Aim: The aim with this study is to compare and analyse the function of the project controller in three project intense knowledge based companies. </p><p>Method: This study is based upon three methodological bases being qualitative study, case study and interview. As a complement to the interviews, document analysis have been used. </p><p>Result: The field of responsibility of accounting controllers is still of great importance, but can be seen as a smaller part of the collected project controller functions. A new area for the function of the project controller stresses constitutes of interaction, which both directly and indirectly supports project control. In the interactive function, both offensive and defensive functions are included, which can be conceived paradoxically. Furthermore the function of the project controller is rather influenced by how companies organise and structure the management control than the importance of the project operation.</p>
16

Controllerns funktioner - En studie i vad som skiljer organisationsformer åt i användandet av controllern

Johansson, Sanna, Waderoth, Maria January 2009 (has links)
<p>I dagens platsannonser frågas det ofta efter controllers, men få vet egentligen vad yrket innebär eftersom rollen skiljer sig från arbetsplats till arbetsplats. Vi ville studera detta diffusa begrepp för att få en större klarhet i vad titeln innebär och vilka arbetsuppgifter som är karakteristiska controlleruppgifter. Syftet med uppsatsen är att beskriva vilka arbetsuppgifter som har störst betydelse i olika organisationer. Utifrån tidigare forskning har vi skapat en modell som visar en uppdelning mellan olika organisationsformer och vilken/vilka av controllerns funktioner som blir extra betonad i de olika.</p><p>Vi har gjort en undersökning omfattande 30 telefonintervjuer med controllers eller personer med motsvarande arbetsuppgifter. Intervjuerna har utgått från en intervjuguide med både öppna och slutna frågor. </p><p>Då vi analyserade vårt empiriska material med hjälp av statistiska tester kom vi fram till att de arbetsuppgifter controllern värderar högst är rapportering, strategiutveckling samt budgetanalys. Vårt material visade även att användandet av controllern skiljer sig i olika organisationsformer. Utifrån våra 22 hypoteser kunde vi statistiskt säkerställa att controllers arbetande i organisationer som befinner sig i en bransch med utmärkande låg eller hög osäkerhet eller i äldre organisationer lägger mindre vikt på budgetering och budgetanalys samt att controllers i den offentliga sektorn lägger större vikt på internkontroll.</p>
17

Controller programming with CoDeSys for an automated timber sorting system

Breitholtz, Nils January 2010 (has links)
<p>This report describes the development of weight measurement application and transducer positioning for the A Sort prototype that has been developed for automatic grading and sorting of timber. The prototype consists of a transportation system with hydraulic and electrical motors, a measurement system with laser scanners and acoustic measurement equipment and a control program for the automated process with CoDeSys. The objective was to integrate these parts in an automatic system process, controlling a prototype designed for acoustic measurement of logs. The devices were installed and configured to communicate via an existing fieldbus line using CANopen as communication protocol. A control program was made for each task and implemented in the control process for the automatic measurement of logs. Two load cells were installed beneath a moving tilt and the measurement equipment was tested and calibrated using three different logs with known weight. The testing showed that in order to get higher accuracy the construction needs to be modified. Photo cells were installed on the measurement frames and a program was made in order to make the acoustic measurement of the logs work properly.</p>
18

Projektverksamhetens"early-warner"- en jämförande studie om projektcontrollerns funktion / The early-warner of the project activity : a comparable study about the funktion of the project controller

Carlsson, Cecilia, Wulff, Renée January 2003 (has links)
Background: The project controller is a function witch evolved due to the strong gaining ground of project operation. Why the area of the project controller is interesting to study is explained by the fact that increasing knowledge of this function is important in order to make project operation work well. The fact that opinions in this field disagree, further increases the interest of the field. In order to study the function of the project controller three companies have been singled out. They are IFS, Intentia and Saab Bofors Dynamics. The selection is based upon them being knowledge based companies with project intense operation. Aim: The aim with this study is to compare and analyse the function of the project controller in three project intense knowledge based companies. Method: This study is based upon three methodological bases being qualitative study, case study and interview. As a complement to the interviews, document analysis have been used. Result: The field of responsibility of accounting controllers is still of great importance, but can be seen as a smaller part of the collected project controller functions. A new area for the function of the project controller stresses constitutes of interaction, which both directly and indirectly supports project control. In the interactive function, both offensive and defensive functions are included, which can be conceived paradoxically. Furthermore the function of the project controller is rather influenced by how companies organise and structure the management control than the importance of the project operation.
19

Controllerns funktioner - En studie i vad som skiljer organisationsformer åt i användandet av controllern

Johansson, Sanna, Waderoth, Maria January 2009 (has links)
I dagens platsannonser frågas det ofta efter controllers, men få vet egentligen vad yrket innebär eftersom rollen skiljer sig från arbetsplats till arbetsplats. Vi ville studera detta diffusa begrepp för att få en större klarhet i vad titeln innebär och vilka arbetsuppgifter som är karakteristiska controlleruppgifter. Syftet med uppsatsen är att beskriva vilka arbetsuppgifter som har störst betydelse i olika organisationer. Utifrån tidigare forskning har vi skapat en modell som visar en uppdelning mellan olika organisationsformer och vilken/vilka av controllerns funktioner som blir extra betonad i de olika. Vi har gjort en undersökning omfattande 30 telefonintervjuer med controllers eller personer med motsvarande arbetsuppgifter. Intervjuerna har utgått från en intervjuguide med både öppna och slutna frågor. Då vi analyserade vårt empiriska material med hjälp av statistiska tester kom vi fram till att de arbetsuppgifter controllern värderar högst är rapportering, strategiutveckling samt budgetanalys. Vårt material visade även att användandet av controllern skiljer sig i olika organisationsformer. Utifrån våra 22 hypoteser kunde vi statistiskt säkerställa att controllers arbetande i organisationer som befinner sig i en bransch med utmärkande låg eller hög osäkerhet eller i äldre organisationer lägger mindre vikt på budgetering och budgetanalys samt att controllers i den offentliga sektorn lägger större vikt på internkontroll.
20

Att tiga är silver, att tala är guld : Framtagningsprocessen av ekonomisk information i tre svenska företag.

Winge, Oscar, Kriborg, Frida January 2013 (has links)
I litteraturen beskrivs controllern väldigt olika från författare till författare, vilket kan förklaras med att controllerrollen varierar från företag till företag, därav är controllerns roll väldigt omdiskuterad angående titel, placering i företaget, dess funktion och arbetsuppgifter. Forskare påpekar att detta är ett område som bör studeras mer. I vår uppsats försöker vi återberätta hur controllerfunktionen beskrivs i tre svenska företag: Duni AB, Höganäs AB och Gekås. Tidigare studier angående controllerns relation gentemot sina ovanställda chefer har visat att den ekonomiska information, produkt, controllern arbetar fram inte är tillfredsställande och i värsta fall irrelevant för beslutsfattandet inom verksamheten. Denna uppsats ämnar beskriva framtagningsprocessen av controllerns produkter, mottagarens uppfattning av slutprodukten samt situationen mellan controllern som producent och ekonomichefen som mottagare i de tre undersökta företagen. Med hjälp av intervjuer med controllern och ekonomichefen på de tre företagen ska vi tolka deras återgivelser och sedan analysera detta mot vår teoretiska referensram med avsikt att finna en förklaring på varför situationer stämmer överrens eller ter sig annorlunda gentemot teorin. Uppsatsens resultat visar att ekonomichefen är tillfredsställd gällande controllerns slutprodukt samt att ekonomichefen och controllern för en nära dialog med varandra kring vilken information som ska tas fram, där även ekonomichefen varit involverad i framtagningsprocessen. Vi har kommit fram till att den informella kommunikationen mellan controller och ekonomichef samt ekonomichefens involvering är den gemensamma faktorn hos företagen som bidragit till att den produkt som tas fram är relevant. / The literature describes the role of the controller very differently, reflecting the fact that the controller role varies from company to company, hence the controller's role is very widely debated regarding title, position in the company, its function and duties. Researchers point out that this is an area that should be studied more. In our paper, we try to retell the role of the controller function as described in three Swedish companies: Duni AB, Höganäs AB and Gekås. Previous studies discussing the controller's relationship towards their CFO has shown that the economic product the controller produce is not satisfactory and at worst irrelevant to decision making within the company. This paper intends to describe the development process of the controller products, the CFO’s perception of the end product and the situation between the controller, as producer, and CFO, as recipients, in the three companies surveyed. Using interviews with the controller and CFO of the three companies, we interpret their stories and then analyze this against our theoretical framework with a view to seek an explanation on why the situation appear differently towards theory. Thesis results show that the CFO is satisfied regarding the end produt. And the CFO and the controller use a close dialogue with each other about what information should be developed, which shows that the CFO has been involved in the development process. We conclude that the informal communication between the controller and the CFO and the involvement of the CFO is the common factor among companies that have contributed to the product being relevant.

Page generated in 0.0642 seconds