• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 59
  • 14
  • 8
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 127
  • 127
  • 33
  • 32
  • 15
  • 15
  • 14
  • 13
  • 13
  • 12
  • 12
  • 12
  • 12
  • 11
  • 10
  • 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

Internet Tools for Machine Design

Dhairyawan, Amit 10 January 2003 (has links)
The aim of this thesis is to provide academic support to the oldest discipline of Mechanical Engineering, namely "Machine Design". The rapid pace of technological development drives every individual, especially students. The industrial revolution in the first half of the 19th century contributed greatly to the advancement of Mechanical Engineering. The theories and experimental data from that time, some developed almost a hundred years ago are still in use in the original form while others have evolved to keep up with the times. This thesis attempts to bring some of that classical machine design theory into a modern user-friendly form that is portable across the Internet. Here the user will be presented with an interactive menu of topics of Machine Design where each is split sub-categorically as Theory and Application. According to the choice made, short excerpts of theory are presented on the chosen matter. The theory will include but not be limited to the important relationships relevant to the design of the particular machine element. After the review of the Theory, the user will be able to navigate to the application where the relationships from the theory will be awaiting user input in the form of solvers. Since the primary emphasis of the thesis is about cultivating knowledge of the underlying theory, the applications will not be self-correcting or self-assuming. The user will need to understand the relationships sufficiently well prior to using the applications to solve homework or design assignments. The created Toolbox is available to all registered users through a login access. The user can then choose to review theory or directly access the applications of the described theory. The thesis successfully demonstrates the use of the Internet as the media for education. / Master of Science
32

Development of a line-start permanent-magnet synchronous machine / Albert Johan Sorgdrager

Sorgdrager, Albert Johan January 2014 (has links)
Electrical machines form part of our everyday life at home and in industry plants. Currently induction machines are the backbone of the industry machine installation as these are robust, reliable and have relatively high efficiency. However as the price of energy increases and stricter efficiency regulations are put into place there is a need for more efficient electrical machines. The majority of induction machines on Sasol's plants are between 2.2 kW and 22 kW. Of these, 95% machines are connected to pump loads and 2% to fan loads. Thus the majority of the machines operate at a constant speed. Rather than try to improve an induction machine, this project proposes the design for a more efficient LS PMSM that can also be used in the same applications as mentioned above. Although LS PMSMs aren’t a new concept, the demand and industry interest in this technology has increased in recent years. Since 2000 the number of research publications with regards to this machine has increased significantly. The goal of this project is to gain a better understanding of these machines by designing a prototype. The design entitles the stator and rotor. As Sasol provided the funding for the project it was decided to design a three phase, 7.5 kW 525V, four-pole machine. During the design phase several design techniques done by other researchers were incorporated into the prototypes. The design is done with the aid of two FEM software packages namely FEMM and ANSYS Maxwell® and verified against calculated values. The final prototype is tested and compared to the predicted values determined during the design. An industry available LS PMSM from Weg, the WQuattro is also used to compare the results of the prototype. The prototype machine’s no-load, full load and locked rotor behaviour is tested as well as the back-emf waveform. From the results gained the machine is validated. The machine did not perform as predicted and further investigation into the reason is needed. Due to the incorrect wiring of the stator and some other rotor manufacturing issues the prototype cannot be fully validated. However it was found that several of the designed values correlated to the measured values. Further investigation into the under performances as well as more relevant testing and practical manufacturing method is needed. / MIng (Electrical and Electronic Engineering), North-West University, Potchefstroom Campus, 2014
33

Development of a line-start permanent-magnet synchronous machine / Albert Johan Sorgdrager

Sorgdrager, Albert Johan January 2014 (has links)
Electrical machines form part of our everyday life at home and in industry plants. Currently induction machines are the backbone of the industry machine installation as these are robust, reliable and have relatively high efficiency. However as the price of energy increases and stricter efficiency regulations are put into place there is a need for more efficient electrical machines. The majority of induction machines on Sasol's plants are between 2.2 kW and 22 kW. Of these, 95% machines are connected to pump loads and 2% to fan loads. Thus the majority of the machines operate at a constant speed. Rather than try to improve an induction machine, this project proposes the design for a more efficient LS PMSM that can also be used in the same applications as mentioned above. Although LS PMSMs aren’t a new concept, the demand and industry interest in this technology has increased in recent years. Since 2000 the number of research publications with regards to this machine has increased significantly. The goal of this project is to gain a better understanding of these machines by designing a prototype. The design entitles the stator and rotor. As Sasol provided the funding for the project it was decided to design a three phase, 7.5 kW 525V, four-pole machine. During the design phase several design techniques done by other researchers were incorporated into the prototypes. The design is done with the aid of two FEM software packages namely FEMM and ANSYS Maxwell® and verified against calculated values. The final prototype is tested and compared to the predicted values determined during the design. An industry available LS PMSM from Weg, the WQuattro is also used to compare the results of the prototype. The prototype machine’s no-load, full load and locked rotor behaviour is tested as well as the back-emf waveform. From the results gained the machine is validated. The machine did not perform as predicted and further investigation into the reason is needed. Due to the incorrect wiring of the stator and some other rotor manufacturing issues the prototype cannot be fully validated. However it was found that several of the designed values correlated to the measured values. Further investigation into the under performances as well as more relevant testing and practical manufacturing method is needed. / MIng (Electrical and Electronic Engineering), North-West University, Potchefstroom Campus, 2014
34

Otimização no balanceamento de mecanismos tri-dimensionais do tipo RSSR. / Optimization for the balancing of three-dimensional mechanisms RSSR.

Coelho, Tarcisio Antonio Hess 02 July 1997 (has links)
Este trabalho trata do emprego de técnicas numéricas de otimização - utilizando o método do Gradiente Reduzido Generalizado - para o balanceamento de mecanismno espaciais ou tri-dimensionais do tipo \"RSSR\". O critério de balanceamento visa a minimização da resultante das forças e da resultante dos momentos de reação na base do mecanismo. As modificações no comportamento dinâmico do mecanismo são realizadas por meio da variação na geometria de contra-pesos acrescentados às peças móveis numa ditribuição de massa \"off-line\". Para verificação dos resultados teóricos, construiu-se uma bancada de ensaios para comparação entre os níveis de vibração da base dos mecanismos desbalenceado e balanceado, ambos funcionando na mesma condição de operação. / The Generalized Reduced Gradient method of numerical optimization was successfully applied in obtaining the reduction of moments and forces transmitted by a spatial RSSR mechanism to its base. Such a modification of dynamical behavior of the mechanism, or balancing, was achieved by the addition of counter-weights attached to the movable links in an off-line position. The evaluation of the obtained optimum configuration has been performed by comparing the measured vibration levels of the base of physical models of the balanced and unbalanced mechanism.
35

Otimização dos ângulos de transmissão na síntese de mecanismos planos de quatro barras. / Optimization of the transmission angle for the synthesis of planar four-bar linkages.

Coelho, Tarcisio Antonio Hess 19 December 1990 (has links)
Este trabalho trata da síntese ótima de mecanismos articulados planos movidos por acionadores prismáticos. O objetivo da síntese é a geração de movimento e trajetória para três e quatro posições. A otimização se refere ao parâmetro ângulo de transmissão. Apresenta-se também, neste trabalho, como os programas de otimização funcionam em exemplos retirados da literatura de projeto de mecanismos. / This work deals with optimum synthesis of four-bar linkages. The synthesis objective is motion and path generation for the threee and four precision. The optimization concerns the parameter transmissin angle. The effectiveness of the optimization programs has been tested using examples obtained from the mechanism design literature.
36

Otimização dos ângulos de transmissão na síntese de mecanismos planos de quatro barras. / Optimization of the transmission angle for the synthesis of planar four-bar linkages.

Tarcisio Antonio Hess Coelho 19 December 1990 (has links)
Este trabalho trata da síntese ótima de mecanismos articulados planos movidos por acionadores prismáticos. O objetivo da síntese é a geração de movimento e trajetória para três e quatro posições. A otimização se refere ao parâmetro ângulo de transmissão. Apresenta-se também, neste trabalho, como os programas de otimização funcionam em exemplos retirados da literatura de projeto de mecanismos. / This work deals with optimum synthesis of four-bar linkages. The synthesis objective is motion and path generation for the threee and four precision. The optimization concerns the parameter transmissin angle. The effectiveness of the optimization programs has been tested using examples obtained from the mechanism design literature.
37

Otimização no balanceamento de mecanismos tri-dimensionais do tipo RSSR. / Optimization for the balancing of three-dimensional mechanisms RSSR.

Tarcisio Antonio Hess Coelho 02 July 1997 (has links)
Este trabalho trata do emprego de técnicas numéricas de otimização - utilizando o método do Gradiente Reduzido Generalizado - para o balanceamento de mecanismno espaciais ou tri-dimensionais do tipo \"RSSR\". O critério de balanceamento visa a minimização da resultante das forças e da resultante dos momentos de reação na base do mecanismo. As modificações no comportamento dinâmico do mecanismo são realizadas por meio da variação na geometria de contra-pesos acrescentados às peças móveis numa ditribuição de massa \"off-line\". Para verificação dos resultados teóricos, construiu-se uma bancada de ensaios para comparação entre os níveis de vibração da base dos mecanismos desbalenceado e balanceado, ambos funcionando na mesma condição de operação. / The Generalized Reduced Gradient method of numerical optimization was successfully applied in obtaining the reduction of moments and forces transmitted by a spatial RSSR mechanism to its base. Such a modification of dynamical behavior of the mechanism, or balancing, was achieved by the addition of counter-weights attached to the movable links in an off-line position. The evaluation of the obtained optimum configuration has been performed by comparing the measured vibration levels of the base of physical models of the balanced and unbalanced mechanism.
38

Design and analysis of a reconfigurable parallel kinematic machine tool.

Modungwa, Dithoto. January 2010 (has links)
Thesis (MTech. degree in Mechanical Engineering)--Tshwane University of Technology, 2010. / This research aimed to develop a Reconfigurable Parallel Kinematic Machine Tool (RPKMT) to be utilized in the maintenance and reconditioning of moulds and dies. The dissertation presents three conceptual designs of a mechanical manipulator, based on specifications required for refurbishing of moulds and dies. Kinematics and mechanical requirements were derived from manufacturing processes and the recommended repair solutions (i.e. steps/operations) required for the specific defect. These requirements resulted in translating customer requirements into engineering/technical characteristics using Quality Function Deployment (QFD) techniques, specifically House of Quality (HoQ). This was followed by the concept design phase, which consisted of the use of the following techniques: Product Function Decomposition and the Morphological Matrix. A comparison study was performed on the conceptual designs, employing kinematic analysis and workspace analysis. The Pugh's Method was used as the concept-selection techniques to aid in selecting the most suitable RPKMT concept. It was for this concept that a model of the design was developed. This phase included selection of the materials for the links, bearing mounts, the base plate and the statics analysis. This was followed by the selection of the link actuators, the spindle drive and the presentation the assembled drawing of the design concept. Finally, a discussion of how the repair process of typical mould/die would be carried out on the RPKMT is presented.
39

A design methodology investigation and the design of a material handling system.

Govender, Daryl Sebastian. January 2000 (has links)
This dissertation is undertaken under the auspices of both the CSIR, Division of Mining Technology and the University of Natal, School of Mechanical Engineering. The CSIR have outlined two fundamental objectives of the dissertation. Firstly, the need for competent design engineers has become increasingly evident. To this end, an evaluation and research into the science of design methodology has been conducted and regarded as a significant component of the thesis. The rationale behind this aim is that the subject of design has been practiced for thousands of years, but an understanding of the process is comparably in its infancy. The importance of the steps involved in the mechanical design process can in no uncertain terms be overemphasized as the adherence there to results in designs that are least likely prone to failure as well as the attainment of highly efficient product design time scales. This is vitally important more especially when the drive towards multifunctional multidisciplinary teams is rapidly developing in the global market place. Secondly, the CSIR, having done the appropriate market research, have defined the need for the design of a timber handling system to be implemented in a deep level mining environment. It is the authors expressed intent not to separate the theory from the design at hand but rather to allow this thesis to become, for the reader, forum where a holistic and integrated approach to design can be presented. / Thesis (M.Sc.)-University of Natal, Durban, 2000.
40

Power feedback control in cylindrical grinding process

Hecker, Rogelio Lorenzo 05 1900 (has links)
No description available.

Page generated in 0.0534 seconds