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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.
51

Modelovací nástroj pro grafický návrh komponentových systémů / A Tool for Modelling of Component-Based Systems

Gál, Ivan January 2009 (has links)
This thesis deals with component software, software frameworks for the Eclipse platform and the creation of a graphical editor for designing component systems with the usage of the Eclipse platform. After introducing the conception of UML component diagram, it describes the overview of component software, components and component technologies of major players on ground of component software: OMG, Sun, Microsoft. A significant part is dedicated to software frameworks for the Eclipse platform for manipulating with meta models. EMF, GEF and GMF are described in more detail. The main part presents the design, implementation and evaluation of a graphical editor for designing component systems with emphasis on understandability and good arrangement.
52

Optimization of Inductive Wireless Charging Systems for Electric Vehicles: Minimizing Magnetic Losses and Limiting Electromagnetic Field Emissions

Mohammad, Mostak 29 August 2019 (has links)
No description available.
53

Ett stycke svensk verklighet : En sociosemiotisk filmanalys av dokumentärfilmen Uppdrag: Skomakarligan / A piece of Swedish reality : A social semiotic film analysis of the documentary film Uppdrag: Skomakarligan

Lauritsen, Elliot January 2024 (has links)
This paper analyzes and interprets the visual communication used to portray the police detectives in the documentary film Uppdrag: Skomakarligan. Four scenes where the police are the main focus and which all have different purposes in the plot of the film are picked out. The four scenes are then studied through a social semiotic method based on Bill Nichols' theories about the documentary voice, and in combination with visual storytelling strategies by Bordwell & Thompson. The filmmaker's power over the image of reality in documentaries is discussed concerning the interpretation that is made. The study results in the police detectives being portrayed as very dedicated to their profession but also shows the human side of them. Filmmaker Hildebrand's fascination with the police detectives, as shown by the narrator, is linked to the result and isn't deemed to be entirely problematic. Media production: In 1975 EMF (Engelholms Musikförening) organized the music festival Musikfesten Tullakrok, and for over 30 years this festival was the highlight of the year for many in Ängelhom. However, in 2008 the festival had to be shut down, but now 16 years later EMF is back and wants to revive Musikfesten Tullakrok for 2024. The purpose of this project was to showcase different members’ perspectives on organizing the music festival 16 years later and provide insight into the history of the festival from 1975 to 2008. A project by Elliot Lauritsen and Ella Hall.
54

Estimation and Compensation of Load-Dependent Position Error in a Hybrid Stepper Motor / Estimering och kompensering av lastberoende positionsfel i en elektrisk stegmotor

Ronquist, Anton, Winroth, Birger January 2016 (has links)
Hybrid stepper motors are a common type of electric motor used throughout industry thanks to its low-cost, high torque at low speed and open loop positioning capabilities. However, a closed loop control is often required for industrial applications with high precision requirements. The closed loop control can also be used to lower the power consumption of the motor and ensure that stalls are avoided. It is quite common to utilise a large and costly position encoder or resolver to feedback the position signal to the control logic. This thesis has explored the possibility of using a low-cost position sensor based on Hall elements. Additionally, a sensorless estimation algorithm, using only stator winding measurements, has been investigated both as a competitive alternative and as a possible complement to the position sensor. The thesis work summarises and discusses previous research attempts to adequately measure or estimate and control the hybrid stepper motors position and load angle without using a typical encoder or resolver. Qualitative results have been produced through simulations prior to implementation and experimental testing. The readings from the position sensor is subject to noise, owing to its resolution and construction. The position signal has been successfully filtered, improving its accuracy from 0.56° to 0.25°. The output from the sensorless estimation algorithm is subject to non-linear errors caused by errors in phase voltage measurements and processing of velocity changes. However, the dynamics are reliable at constant speeds and could be used for position control.
55

Analysis of a radial flux-air-cored permanent magnet machine with a double-sided rotor and non overlapping windings

Randewijk, Peter-Jan 03 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: In this dissertation a new type of electrical machine, a Radial Flux Air-Cored Permanent Magnet machine with a Double-sided Rotor and utilising concentrated, non-overlapping windings, is proposed. The concept of the Double-sided Rotor Radial Flux Air-Cored Permanent Magnet machine, or RFAPM machine for short, was derived from the Double-sided Rotor Axial Flux Air-Cored Permanent Magnet (AFAPM) machine. One of the problems that AFAPM machines experience, is the deflection of the rotor discs due to the strong magnetic pull of the permanent magnets, especially with double-sided rotor machines. The main advantage of a RFAPM machine over a AFAPM machine is that the rotor back-iron is cylindrically shaped instead of disk shaped. Due to the structural integrity of a cylinder, the attraction force between the two rotors does not come into play any more. The focus of this dissertation is on a thorough analytical analysis of the Double-Sided Rotor RFAPM machine. With the RFAPM being an air-cored machine, the feasibility to develop a linear, analytical model, to accurately predict the radial flux-density and hence the induced EMF in the stator windings, as well as the accurate calculation of the developed torque of the machine, needed to be investigated. The need for a thorough analytical examination of the Double-Sided Rotor RFAPM machine stemmed from the need to reduce the blind reliance on Finite Element Modelling (FEM) software to calculate the back-EMF and torque produced by these machines. Another problem experienced with the FEM software was to obtain accurate torque results. Excessive ripple torque oscillations were sometimes experienced which took a considerable amount of time to minimise with constant refinement to the meshing of the machine parts. Reduction in the mesh element size unfortunately also added to the simulation time. The requirement for an accurate analytical model of the RFAPM machine was also necessary in order to reduce the amount of time spent on successive FEM simulation to obtain the optimum pole arc width of the permanent magnet in order to minimise the harmonic content of the radial flux-density distribution in the the stator windings. In this dissertation, the use of single-layer and double-layer, non-overlapping, concentrated winding for the RFAPM machine is also investigated. It was decided to include a comparison of these two non-overlapping winding configurations with a “hypothetical” concentrated, overlapping winding configuration. This would allow us to gauge the effectiveness of using nonoverlapping winding with respect to the reduction in copper losses as well as in the reduction in copper volume. It would also allow us to investigate the extent of how much the developed torque is affected by using non-overlapping windings instead of overlapping windings. / AFRIKAANSE OPSOMMING: In hierdie proefskrif word ’n nuwe tipe elektriese masjien, ’n Radiale-vloed Lugkern Permanent Magneet Masjien met ’n dubbelkantige rotor en nie-oorvleuelende Windings voorgestel. Die konsep vir die Radiale-vloed Lugkern Permanent Magneet Masjien, of RVLPM vir kort, is afgelei vanaf die Dubbelkantige Rotor, Aksiale-vloed Lugkern (AVLPM) masjien. Een van die probleme wat met AVLPM masjiene ondervind word, is die defleksie van die rotorjukke as gevolg van die sterk aantrekkingskragte van die permanente magnete, veral in dubbelkantige rotor masjiene. Die hoof voordeel wat die RVLPM masjien inhou bo die AVLPM masjien, is die feit dat die RVLPM se rotorjukke silindries is in plaas van ronde skywe. As gevolg van die strukturele integriteit van ’n silinders, speel die aantrekkingskrag van die permanente magnete nie meer ’n rol nie. Die fokus van die proefskrif gaan oor die deeglike analitiese analise van die dubbelkantige RVLPM masjien. Weens die feit dat die RVLPM masjien ’n lugkern masjien is, is daar besluit om ondersoek in te stel na die moontlikheid om ’n lineêre, analitiese model vir die masjien op te stel waarmee die radiale-vloeddigtheid, teen-EMK asook die ontwikkelde draaimoment vir die masjien akkuraat bereken kan word. Die behoefde aan ’n akkurate analitiese model vir die dubbelkantige rotor RVLPM masjien is om die blinde vertroue te elimineer wat daar in Eindige-Element Modellering (EEM) sagteware gestel word om die teen-EMK en ontwikkelde draaimoment van die RVLPM masjien uit te werk. ’n Verdere probleem wat daar met EEM sagteware ondervind is, is die akkurate berekening van die ontwikkelde draaimoment. Oormatige rimpel draaimoment ossillasies is soms ondervind wat heelwat tyd geverg het om te minimeer, deur voortdurende verfyning van die EEM maas in die verskillende dele van die masjien. Soos die maas egter kleiner word, verleng dit die simulasie tyd van die EEM aansienlik. Nog ’n rede vir ’n akkurate analitiese model van die RVLPM masjien, is om vinnige metode te verkry om die optimale permanente magneet pool hoekwydte te verkry, wat die minste Totale Harmoniese Vervorming (THV) in die radiale-vloeddigtheidsdistribusie in die statorgebied sal veroorsaak, sonder om herhaaldelike EEM simulasies te loop. In die proefskrif word die gebruik van enkellaag en dubbellaag, nie- oorvleuelende, gekonsentreerde wikkelings vir die RVLPM masjien ook ondersoek. Daar is besluit om hierdie twee nie-oorvleuelende windingskonfigurasies met ’n “hipotetiese” gekonsentreerde, oorvleuelende windingskonfigurasie te vergelyk. Dit behoort ons in staat te stel om die doeltreffendheid van nie-oorvleuelende windings te bepaal, met betrekking tot die afname in koperverliese asook die afname in kopervolume. Verder sal dit ons in staat stel om ook mate waartoe die ontwikkelde draaimoment deur nie-oorvleuelende windings beïnvloed word, te ondersoek.
56

用於圖形化編輯器開發之專屬模型語言設計 / A Modeling Language of Domain Specific Editors Based on Graphical Modeling Framework

呂宗龍, Lv,Zong-Long Unknown Date (has links)
圖形化模型編輯器是模型編輯器開發長久以來一直努力的方向。Eclipse.org 已提供兩個功能強大的圖形化編輯器設計框架:GEF 圖形化編輯器設計框架,和將 EMF 與 GEF 結合並簡化其設計流程的 GMF 圖形化模型編輯器設計框架,來協助開發者發展圖形化模型編輯器。 / 使用設計框架時所面臨的高學習門檻是開發者選用設計框架上的一大障礙。為降低開發者在 GMF 使用上的學習門檻,我們希望能提供一個以模型開發為導向的圖形編輯器設計專屬模型語言,讓程式設計師能夠以其慣用的程式設計角度來描述其圖形化模型編輯器的組成架構。 / 本篇研究主要是在探討 GMF 圖形化模型編輯器開發流程的簡化。在研究中希望藉由提供 GMF 圖形化模型編輯器設計框架的 GM3 專屬模型語言,讓開發者能夠透過 MDA 的角度來開發圖形化模型編輯器的架構,藉以縮短 GMF 的開發流程。實驗中使用 JavaCC 文法剖析器產生工具來開發 GM3專屬模型語言與 GMF 各項模型定義間的模型轉換。 / The availability of a visual graphical editor for a target domain is the prerequisite of visual graphical modeling, which has been adopted by classical software development for decades and is especially emphasized in today's model-driven engineering. However, compared with traditional textual editors, developing a visual graphical editor from scratch is not an easy work. As a result, there were frameworks developed such as GEF and GMF aimed to simplify the construction of graphical editors. Even so, however, it is still though hard for an average programmer to construct a visual graphical editor by using these frameworks without a long time of learning. / Our result is a modeling langauge of graphcial editors called GM3, serving as a bridge betwen developers of graphical editors and the GMF framework. With GM3, the developer can specify the model of his editing domain, how each model element should be presented by which kind of graphical elements in the editor, and how the tool pallete should be filled with various kind of creation and manipulation tools for model elements. After the GM3 specification of an editor is produced, the GM3 transformation engine developed by us using the JavaCC parser generator can be used to generate all files required of the GMF framework and, finally, a subsequent application of the standard GMF code generation procedure can produce a complete graphical editor on Eclipse platform.
57

Effects of EMF Emissions from Undersea Electric Cables on Coral Reef Fishes

Jermain, Robert F 18 July 2016 (has links)
The objective of this project was to determine if the electromagnetic field (EMF) emissions from undersea power cables impacted the local and transient marine life, with an emphasis on reef fishes. The work was done at South Florida Ocean Measurement Facility of Naval Surface Warfare Center, Carderock Division, Broward County, Florida. This facility functions as the hub for a range of active undersea detection and data transmission cables. It has multiple active submarine power cables that extend several miles offshore and which can deliver power and enable data transmission to and from a range of acoustic and EMF sensors. The cables lie directly on the seabed, are buried in the sand, or are suspended in the water column. EMF emissions from a selected cable were created during SCUBA fish surveys. During the surveys the transmission of either alternating current (AC) or Direct Current (DC) was randomly intiated by the facility with no transmitted current (OFF) provided a control. The surveys were conducted using standardized transect and stationary point count methods to acquire reef fish abundances prior to and immediately after a change in transmission frequency (the divers were aware of the time of frequency change but not the specific frequencies). The divers were also tasked to note the reaction of the reef fishes to the immediate change in the EMFs emitting from the cable during a power switch. The surveys were conducted on a quarterly basis at three sampling sites offshore on the same cable. These sites were in water depths of approximately 5, 10, and 15 m, respectively and were selected based on their robust reef fish community and are representative of each of the three primary hardbottom coral reef habitats in the local offshore environment: the Inner (Shallow), Middle, and Outer (Deep) reef tracts. A total of 263 surveys were conducted: 132 transect-counts and 131 point-counts over 15 months. There were 24,473 fishes counted during transect-count surveys and with point-counts, 36,115 fishes were counted. With count types and sites combine a total of 151 species representing 35 families were recorded. An analysis of the data primarily did not find statistical differences among power states and any variables. However, this may be a Type II error as there are strong indications of a potential difference of a higher abundance of reef fishes at the sites when the power was off. There are a number of caveats to consider with this finding: the data set needs to be larger in terms of numbers of: counts, sites and eletro-sensitive species to allow for rigorous statistical analysis; also a longer time between frequency changes to allow for slower, but nonetheless important, reactions to differing EMFs might lead to differing conclusions. Obviously, more research is required to confirm the results of this study.
58

Quantitative equilibrium calculations on systems with relevance to copper smelting and converting

Björkman, Bo January 1984 (has links)
The present thesis gives a summary of results obtained through theoretical and experimental studies of systems with relevance to copper smelting and converting. Many chemical elements are involved in the copper production pro­cesses and a detailed experimental study would be very time- consuming and expensive. A complicating fact is also the corrosivity of the liquid phases towards container material. A powerful alternative is equilibrium calculations, in which models for the liquid phases as well as reliable basic thermodynamic data are needed. In the present thesis, a generalized structure based model for liquid silicates was developed and used in assessments of the sys­tems PbO-SiO2, Fe-O-SiO2, CuO0.5-SÌO2 and Cu-Fe-O-SiO2. In the model, the non-ideal silicate melt is treated as an ideal solu­tion but containing a few complexes. The PbO-Si02 melt could be described by introducing the complexes Pb3Si207, Pb4Si4010 and Pb13Si12O37 in addition to the components PbO and Pb2Si04. The species considered in the Fe-O-SiO2 melt were FeO, FeO1.5, Fe2Si04, Fe3Si207, Fe3Si6O15 and in the CUO0.5-SiO2 melt CuO0.5 ana CU4SiO4. Trie calculated phase diagrams, the activities of me­tal oxides and the oxygen partial pressures were all in good agreement with the published data. Two of the papers in this thesis concern the determination of Gibbs free energies for Cu2S(s,l) and Ca2Fe2O5(s) through emf measurements utilizing a solid electrolyte. Activities and termi­nal solubilities in the solid solution [Fet,Ca]0 were also deter­mined. The results obtained from the quantitative equilibrium calcula­tions for conventional copper smelting and converting were used to outline the overall reactions taking place and the outcome of changes in process parameters. Comparison with observed values, however, showed that the copper and magnetite contents in slag were calculated too low. These discrepancies could be completely explained by using a non-equilibrium approach in which the con­verter was assumed to consist of several segments with concentra­tion gradients between the segments. / digitalisering@umu.se
59

Developing a Graphical Application to Control Stepper Motors with Sensorless Load Detection

Adolfsson, Mattias January 2021 (has links)
For positioning of linear stages in absolute coordinates, there is a general need to find a reference position since the initial one is unknown. This is commonly called homing. To reduce costs and facilitate assembly, homing can be performed without additional sensors, known as sensorless homing. This thesis delves into sensorless homing, specifically with respect to stepper motors, and develops a graphical application for control of them. The commercial technology StallGuard is applied inconjunction with exploration into how it – and sensorless load detectionin general – functions. The resulting graphical application can be used to configure the stepper motors, perform homing using StallGuard, and automatically tune StallGuard to work despite varying conditions. In addition, rudimentary sensorless load detection independent from StallGuard is developed, demonstrating how it could work in practice. Testing shows homing with StallGuard resulting in a position within a ±5μm window in 94% of cases, less than 1/7 the width of an average strand of human hair. Additionally, homing is easily performed with a single button press from the graphical interface, with optional additional configuration available.
60

Towards Attribute Grammars for Metamodel Semantics

Bürger, Christoff, Karol, Sven 15 August 2011 (has links)
Of key importance for metamodelling are appropriate modelling formalisms. Most metamodelling languages permit the development of metamodels that specify tree-structured models enriched with semantics like constraints, references and operations, which extend the models to graphs. However, often the semantics of these semantic constructs is not part of the metamodel, i.e., it is unspeci ed. Therefore, we propose to reuse well-known compiler construction techniques to specify metamodel semantics. To be more precise, we present the application of reference attribute grammars (RAGs) for metamodel semantics and analyse commonalities and differences. Our focus is to pave the way for such a combination, by exemplifying why and how the metamodelling and attribute grammar (AG) world can be combined and by investigating a concrete example - the combination of the Eclipse Modelling Framework (EMF) and JastAdd, an AG evaluator generator.

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