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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.
31

Development Of A Computer Program For Friction Winding Systems

Unal, Fuat Gokhan 01 October 2011 (has links) (PDF)
ABSTRACT DEVELOPMENT OF A COMPUTER PROGRAM FOR FRICTION WINDING SYSTEM DESIGN &Uuml / nal, Fuat G&ouml / khan M.Sc., Department of Mining Engineering Supervisor: Prof. Dr. Naci B&ouml / l&uuml / kbasi September 2011, 99 pages As the trend to deeper mines continues, mine hoists and associated equipment will become more sophisticated, complex, large and expensive. Correct selection of the right type of hoist is imperative. In this vital link between underground and surface, crude estimates of hoist capacity are not good enough, and the mining engineer must design and select the right hoisting system to meet the design specifications and establish the most suitable operating parameters. This study aims to constitute a software model, which results all required design parameters of friction type winding system on minimum required power. The computer program has been structured on Microsoft Visual Basic programming language. The program requires user inputs (winding depth, hourly hoisting capacity) and selections (type and number of motors, type of friction wheel mounting) to run macros and equations so that the operating parameters such as skip capacity, rope type and diameter, hoisting speed, acceleration, cycle period, friction wheel diameter are determined to give the minimum motor power requirement.
32

Otimização aplicada ao projeto de enrolamentos de máquinas CA / Applied optimization to AC windings design

Franco, André Luiz Carneiro 15 September 2015 (has links)
Submitted by Erika Demachki (erikademachki@gmail.com) on 2016-01-07T14:42:53Z No. of bitstreams: 2 Dissertação - André Luiz Carneiro Franco - 2015.pdf: 2564368 bytes, checksum: 93761b2c7af9677536a7897fd4aa57f3 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Erika Demachki (erikademachki@gmail.com) on 2016-01-07T14:44:04Z (GMT) No. of bitstreams: 2 Dissertação - André Luiz Carneiro Franco - 2015.pdf: 2564368 bytes, checksum: 93761b2c7af9677536a7897fd4aa57f3 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2016-01-07T14:44:04Z (GMT). No. of bitstreams: 2 Dissertação - André Luiz Carneiro Franco - 2015.pdf: 2564368 bytes, checksum: 93761b2c7af9677536a7897fd4aa57f3 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2015-09-15 / Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEG / This work presents an analysis and optimization metho dology for the AC machines stator windings design, based on magnetomotive force harmonic distortion study. For that, the three-phase double layer integral and fractional-slot windings are chosen. At first, magnetomotive force in conventional windings study is p erformed, comparing harmonic analysis by distortion and Fourier sp ectrum with the traditional calculation metho dology of winding factors. In relation to the metho d, the stator windings arrangement optimization using genetic algorithms is prop osed, in order to suggest alternative optimized layouts. The results are presented and discussed. / Este trabalho apresenta metodologia para análise e otimização de geometrias de enrolamentos de estator de máquinas CA, baseada no estudo da distorção harmônica associada à curva de força magnetomotriz no entreferro. Para tal, opta-se p elo estudo dos enrolamentos trifásicos de dupla camada integrais e fracionários. Primeiramente é realizado o estudo da força magnetomotriz dos enrolamentos convencionais, confrontando a análise harmônica através da distorção e espectro de Fourier com a metodologia tradicional de cálculo dos fatores de enrolamento. Definido o método, propõe-se a otimização do arranjo de enrolamentos de estator utilizando algoritmos genéticos, com o objetivo de sugerir geometrias alternativas otimizadas. Os resultados obtidos são apresentados e discutidos.
33

Contribuição ao projeto estrutural de cilindros em compósitos para armazenamento de oxigênio sob alta pressão / A contribution to the structural design of composite cylinders for high-pressure oxygen containment

Hitoshi Taniguchi 30 March 2009 (has links)
Neste trabalho são analisados os aspectos relacionados à otimização estrutural de cilindros de alta pressão em compósitos, a partir do estudo detalhado dos procedimentos de cálculo analítico, utilizando o método análise de rede (netting analysis), juntamente com procedimentos baseados em análise numérica pelo método dos Elementos Finitos, considerando modelos de comportamento ortotrópico do material compósito. São considerados cilindros utilizados para armazenamento de oxigênio, fabricados pelo processo de enrolamento filamentar (filament winding), comparados a cilindros confeccionados em metal quanto à sua aplicabilidade. Após análise de diferentes estudos de caso, conclui-se que os materiais compósitos podem ser aplicados com sucesso em cilindros de alta pressão, desde que estabelecidos alguns parâmetros decisivos ao projeto estrutural do vaso, tais como: critério de falha mais adequado; determinação de dados experimentais dos materiais utilizados; normas e códigos utilizados no projeto e dados da geometria final do vaso, dependentes do processo de fabricação. Propõe-se também a utilização de um ambiente integrado das atividades de projeto e fabricação do compósito. / In this work the aspects related to the structural optimization of composite high-pressure cylinders are analyzed from the thorough study of analytical calculation, by the use of netting analysis, along with procedures based on numerical analysis by the Finite Element method, considering models of composite materials with orthotropic behaviour. Cylinders used for oxygen containment, manufactured by filament winding process, are considered and compared to the cylinders manufactured in metal in terms of their application. The analyses of different case studies allowed to conclude that composite materials can be applied successfully in high pressure cylinders provided that some critical parameters have been established to the vessel structural design, such as: an adequate failure criteria; determination of experimental data for the composite materials used; standards and codes used in the design and the final vessel geometry data, dependent variables of the manufacturing process. An integrated environment of the design and manufacturing activities is proposed as well in order to embrace all of these aspects.
34

Partial Discharge Characteristics under Square-wave Voltage Pulses with Ultra-short Rise Times under Various Pressures

Wei, Zhuo 24 August 2022 (has links)
No description available.
35

Electrified Vehicle Traction Machine Design With Manufacturing Considerations

Yang, Rong January 2017 (has links)
This thesis studies the brushless permanent magnet synchronous (BLPM) machine design for electric vehicle (EV) and hybrid electric vehicle (HEV) application. Different rotor topologies design, winding design, and multiphase designs are investigated and discussed. The Nissan Leaf interior permanent magnet (IPM) traction machine has been widely analyzed and there is much public domain data available for the machine. Hence, this machine is chosen as a representative benchmark design. First, the Nissan Leaf machine is analyzed via finite element analysis (FEA) and the results confirmed via published experimental test data. The procedure is then applied to all the following machine designs and results compared. Then the Nissan Leaf machine rotor is redesigned to satisfy the performance specification with sinusoidal phase current in the full range for the same performance specification and permanent magnet material. Afterword, a comparative study assessing the design and performance attributes of the Nissan Leaf IPM machine, when compared to a surface permanent magnet (SPM) machine designed within the main Nissan Leaf machine dimensional constraints. The study illustrates and concludes that both the IPM and SPM topologies have very similar capabilities with only subtle differences between the design options. The results highlight interesting manufacturing options and materials usage. The grain boundary diffusion processed (GBDP) magnets are proposed to reduce the rare earth material content in the permanent magnet machines, especially subject to high load and high temperature operating scenarios by preventing or reducing the onset of demagnetization. The design and analysis procedure of BLPM machine with GBDP magnets are put forward. In the end, the Nissan Leaf IPM machine is taken as an example to verify the analysis procedure. and the results illustrates that IPM machines with GBDP magnets can realize torque and maintain efficiency at high loads while being less prone to demagnetization. A new multi-phase synchronous reluctance machine (SRM) with good torque performance and conventional voltage source inverter is introduced for traction machine applications. Although the torque density is low compared with BLPM machine, the SRM machine gets rid of permanent magnets and achieve low torque ripple compared with switched reluctance machine when the asymmetric inverter is replaced with conventional voltage source inverter. The concentrated windings are designed and studied with both IPM and SPM rotor according to the Nissan Leaf machine requirements of performance and dimension to investigate how the concentrated windings affect the machine performance and manufacturability and cost. 9-, 12-, 15- slot concentrated windings’ stator share the same slot area with the Nissan Leaf machine distributed winding and the performance are evaluated and compared. Multi-phase concentrated windings machines with IPM and SPM rotor are designed and analyzed based on the Nissan Leaf machine specification and dimension constraints. The performance of 23-phase, 5-phase, 9-phase machine at low speed and top speed are studied and the advantages and disadvantages are compared in terms of torque quality, efficiency, and power electronic requirements. / Thesis / Doctor of Philosophy (PhD)
36

Measurement and modelling of unbalanced magnetic pull in hydropower generators

Wallin, Mattias January 2013 (has links)
Hydropower research is often perceived to be an old and exhausted field of study but with ageing equipment and the need for more intermittent operation caused by an increased share of other renewable energy sources new challenges lie ahead. The main focus of this dissertation are the electromagnetic forces resulting from nonuniform air gap flux, whether it be caused by rotor eccentricity or a faulty field winding. Results are predominantly obtained from measurements on an experimental generator and numerical simulations. With the computational capacity available today it is possible to numerically analyse physical phenomena that previously could only be studied with analytical tools. Numerical models can also be expanded to encompass more than one aspect of generator operation in coupled field-circuit models without model complexity surpassing computer capability. Three studies of unbalanced magnetic pull, UMP, in synchronous salient pole generators constitute the main part of this thesis. The first is a study of how parallel stator circuits affect the unbalanced magnetic pull caused by rotor eccentricity. Depending on the relationship between the geometry of the separate circuits and the direction of the eccentricity it was found that parallel circuits could reduce the UMP substantially. Secondly, an investigation of the effect of damper winding configuration on UMP was performed. The results showed that damper winding resistivity and the distance between the damper bars in a pole determine the effectiveness of the damper winding in reducing the UMP. Simulations of a production machine indicate that the reduction can be substantial from damper windings with low resistivity. The third study analyses the consequences of field winding interturn short circuits. Apart from a resulting rotating unbalanced magnetic pull it is found that the unaffected poles with the same polarity as the affected pole experience an increase in flux density. In a fourth article a new stand still frequency response, SSFR, test method including measurements of damper winding voltage and current is presented. It is found that the identified models are capable of predicting the stator to damper transfer function both with and without the damper winding measurements included.
37

Estudo do comportamento mecânico de cilindros de compósito epóxi/fibra de basalto em ensaios hidrostáticos / Study of mechanical behavior of epoxy/basalt fiber composite cylinders under hydrostatic tests

Mauro Henrique Lapena 26 January 2017 (has links)
O objetivo deste trabalho foi estudar o comportamento mecânico de cilindros de compósito polimérico reforçado com fibras. Para isso, foram produzidos cilindros com extremidades abertas reforçados com fibra de basalto e fibra de vidro, utilizando a técnica de enrolamento filamentar (filament winding). Estes cilindros foram submetidos a ensaio hidrostático com carregamento circunferencial, ensaio de ruptura de anel (split disk test) e ensaio de resistência ao cisalhamento interlaminar (ILSS). Uma placa do compósito de fibra de basalto foi produzida por enrolamento filamentar, para caracterização por ensaio de resistência à tração. Todos cilindros submetidos ao ensaio hidrostático apresentaram fratura localizada em uma faixa de altura do cilindro, com extensas delaminações das camadas circunferenciais. Os compósitos epóxi/fibra de basalto superaram ou igualaram os de compósito epóxi/fibra de vidro nas comparações entre resultados dos valores das propriedades mecânicas avaliadas, nas porcentagens: resistência à tração aparente de ruptura de anel em 45% e 43% em resistência específica; ILSS, em 11%; resistência/tensão de membrana de ruptura no ensaio hidrostático, em 55%. / The aim of this work was to study the mechanical behavior of fiber reinforced polymer composite cylinders. For this purpose, cylinders reinforced with basalt and glass fibers were produced, with open-ended geometry, using filament winding technique. These cylinders were submitted to hydrostatic test under circunferential loading, split disk (ring segment) test and interlaminar shear strength (ILSS). A basalt fiber composite plate was produced by filament winding for characterization by tensile strength test. All cylinders submitted to hydrostatic test presented fracture located in the height range of the cylinder, with extensive delamination of the circumferential layers. The epoxy/basalt fiber composites overcame or equated the epoxy/glass fiber composites in comparisons between results of the mechanical properties, tensile strength in split disk, in 45% and 43% in specific strength; ILSS in 11%; membrane tensile strength in the hydrostatic test, in 55%.
38

Estudo do comportamento mecânico de cilindros de compósito epóxi/fibra de basalto em ensaios hidrostáticos / Study of mechanical behavior of epoxy/basalt fiber composite cylinders under hydrostatic tests

Lapena, Mauro Henrique 26 January 2017 (has links)
O objetivo deste trabalho foi estudar o comportamento mecânico de cilindros de compósito polimérico reforçado com fibras. Para isso, foram produzidos cilindros com extremidades abertas reforçados com fibra de basalto e fibra de vidro, utilizando a técnica de enrolamento filamentar (filament winding). Estes cilindros foram submetidos a ensaio hidrostático com carregamento circunferencial, ensaio de ruptura de anel (split disk test) e ensaio de resistência ao cisalhamento interlaminar (ILSS). Uma placa do compósito de fibra de basalto foi produzida por enrolamento filamentar, para caracterização por ensaio de resistência à tração. Todos cilindros submetidos ao ensaio hidrostático apresentaram fratura localizada em uma faixa de altura do cilindro, com extensas delaminações das camadas circunferenciais. Os compósitos epóxi/fibra de basalto superaram ou igualaram os de compósito epóxi/fibra de vidro nas comparações entre resultados dos valores das propriedades mecânicas avaliadas, nas porcentagens: resistência à tração aparente de ruptura de anel em 45% e 43% em resistência específica; ILSS, em 11%; resistência/tensão de membrana de ruptura no ensaio hidrostático, em 55%. / The aim of this work was to study the mechanical behavior of fiber reinforced polymer composite cylinders. For this purpose, cylinders reinforced with basalt and glass fibers were produced, with open-ended geometry, using filament winding technique. These cylinders were submitted to hydrostatic test under circunferential loading, split disk (ring segment) test and interlaminar shear strength (ILSS). A basalt fiber composite plate was produced by filament winding for characterization by tensile strength test. All cylinders submitted to hydrostatic test presented fracture located in the height range of the cylinder, with extensive delamination of the circumferential layers. The epoxy/basalt fiber composites overcame or equated the epoxy/glass fiber composites in comparisons between results of the mechanical properties, tensile strength in split disk, in 45% and 43% in specific strength; ILSS in 11%; membrane tensile strength in the hydrostatic test, in 55%.
39

Analysis of interior permanent magnet motors with non-overlapping windings

Germishuizen, Johannes Jacobus 03 1900 (has links)
Thesis (PhD (Electrical and Electronic Engineering))--University of Stellenbosch, 2009.
40

Topology based representations for motion synthesis and planning

Ivan, Vladimir January 2015 (has links)
Robot motion can be described in several alternative representations, including joint configuration or end-effector spaces. These representations are often used for manipulation or navigation tasks but they are not suitable for tasks that involve close interaction with the environment. In these scenarios, collisions and relative poses of the robot and its surroundings create a complex planning space. To deal with this complexity, we exploit several representations that capture the state of the interaction, rather than the state of the robot. Borrowing notions of topology invariances and homotopy classes, we design task spaces based on winding numbers and writhe for synthesizing winding motion, and electro-static fields for planning reaching and grasping motion. Our experiments show that these representations capture the motion, preserving its qualitative properties, while generalising over finer geometrical detail. Based on the same motivation, we utilise a scale and rotation invariant representation for locally preserving distances, called interaction mesh. The interaction mesh allows for transferring motion between robots of different scales (motion re-targeting), between humans and robots (teleoperation) and between different environments (motion adaptation). To estimate the state of the environment we employ real-time sensing techniques utilizing dense stereo tracking, magnetic tracking sensors and inertia measurements units. We combine and exploit these representations for synthesis and generalization of motion in dynamic environments. The benefit of this method is on problems where direct planning in joint space is extremely hard whereas local optimal control exploiting topology and metric of these novel representations can efficiently compute optimal trajectories. We formulate this approach in the framework of optimal control as an approximate inference problem. This allows for consistent combination of multiple task spaces (e.g. end-effector, joint space and the abstract task spaces we investigate in this thesis). Motion generalization to novel situations and kinematics is similarly performed by projecting motion from abstract representations to joint configuration space. This technique, based on operational space control, allows us to adapt the motion in real time. This process of real-time re-mapping generates robust motion, thus reducing the amount of re-planning. We have implemented our approach as a part of an open source project called the Extensible Optimisation library (EXOTica). This software allows for defining motion synthesis problems by combining task representations and presenting this problem to various motion planners using a common interface. Using EXOTica, we perform comparisons between different representations and different planners to validate that these representations truly improve the motion planning.

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