• 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.
41

A co-evolutionary multi-agent approach for designing the architecture of reconfigurable manufacturing machines

Young, Nathan 05 May 2008 (has links)
Manufacturing companies today face increasingly uncertain and volatile market demands. Product designs and the required quantities change rapidly to meet the needs of customers. To maintain competitiveness in this uncertain environment, manufacturing companies need to possess agility to dynamically and effectively adapt to the changing environment. Agility at the machine level can be thought of as the ability to reconfigure manufacturing machines in response to changing needs and opportunities. This thesis is concerned with a design method for machine level agility for reconfigurable manufacturing machines. This thesis is divided into two portions: a design approach for reconfigurable manufacturing machines and the embodiment of this approach in a computational synthesis example. In developing this design method, various approaches and reconfigurable systems are presented to develop an overview of the applications and current related research to reconfigurable manufacturing machines. From this related research, a research gap is identified pertaining to the identification of the evolving architecture of reconfigurable manufacturing machines. The key contribution is the design approach based on co-evolution. This design approach involves the implementation of agent based co-evolutionary algorithms. In this implementation, each agent synthesizes the configuration of a machine for a product in the range of products it is to manufacture and co-evolves with other agents which are synthesizing machines for other products to reduce the reconfiguration cost. Finally, an in-depth case study of the design approach is presented in which the approach is tested relative to various product changes; thus, showing the advantages of employing an evolving reconfigurable machine architecture. These product changes include batch size variations, geometry changes, and material changes. Hence, the core objective is to identify the necessary reconfigurable manufacturing machine architecture for the range of configurations required for machining various products.
42

Finite element modeling and machine design for powder compaction in a cylindrical mold /

Wen, Guoping, January 1998 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 159-163). Also available on the Internet.
43

Finite element modeling and machine design for powder compaction in a cylindrical mold

Wen, Guoping, January 1998 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 159-163). Also available on the Internet.
44

Ortho-planar mechanisms for microelectromechanical systems /

Lusk, Craig P., January 2005 (has links) (PDF)
Thesis (Ph. D.)--Brigham Young University. Dept. of Mechanical Engineering, 2005. / Includes bibliographical references (p. 199-214).
45

Ferramenta pneumática para movimentação de carrocerias rodoviárias em linhas de montagem / Pneumatic tool to drive road vehicles on assembly lines

Taborda, Gustavo Gomes January 2009 (has links)
Este trabalho apresenta um estudo de caso na indústria de implementos e veículos rodoviários para solução do processo específico de movimentação de veículos e carrocerias rodoviárias nas linhas de montagem. A solução é o desenvolvimento do projeto de uma ferramenta pneumática para atender os parâmetros identificados no processo de movimentação utilizando uma metodologia de projeto. A metodologia adotada é uma composição de modelos sugeridos por autores mostrando uma sequência clara e objetiva do ciclo de vida do projeto, estruturada em quatro fases principais: Projeto Informacional, Projeto Conceitual, Projeto Executivo e Otimização de Projeto. A identificação das informações relevantes ao processo de movimentação dos produtos deu início ao Projeto Informacional. Com a finalidade de conhecer melhor as características dos processos dos potenciais usuários da ferramenta, foram levantadas as características e os parâmetros do processo. Os parâmetros abordam as principais grandezas envolvidas no sistema e suas limitações. Os dados resultantes do levantamento foram analisados gerando uma síntese de todos os parâmetros identificados para o desenvolvimento das próximas fases. No projeto conceitual, houve a evolução da solução através do detalhamento de um conceito, escolhido mediante a proposição de alternativas durante a geração de conceitos. O detalhamento é apresentado através de desenhos, segundo a diretriz de projeto orientado ao computador, com base na estrutura funcional de funcionamento da ferramenta, salientando os principais sistemas e suas configurações. Os dimensionamentos são apresentados no projeto executivo e contemplam dois tipos de análise: a análise cinemática e a análise estrutural do sistema. Na análise cinemática são apresentadas duas propostas de configuração para o motor pneumático que será utilizado na ferramenta. As propostas são expostas através de desenhos de montagem, desenhos explodidos e gráficos dos parâmetros do motor pneumático para cada uma das configurações adotadas. Nesta fase também é mostrada a construção do protótipo. Os resultados do projeto são obtidos através da realização de teste em bancada e em campo para confirmação dos parâmetros estabelecidos. Completando o ciclo de vida do projeto, propõem-se as tendências evolutivas, analisando as possíveis melhorias para a ferramenta. As conclusões do trabalho são baseadas nos resultados apresentados nos testes realizados com a ferramenta, na eficiência da metodologia adotada para o desenvolvimento do projeto e na análise do cumprimento dos objetivos definidos no trabalho. / This paper presents a case study in industry of road road vehicles for solution of the specific handling of road vehicles and truck trailers in assembly lines. The solution is to develop the design of a pneumatic tool to meet the criteria identified in the move process using a design methodology. The methodology used is a composite of models suggested by the authors showed a clear sequence and objective of the life cycle of the project, divided into four main phases: Informational Design, Conceptual Design, Executive Design and Optimization Project. The identification of information relevant to the process of transferring products initiated the Informational Design. In order to better understand the nature of the processes of potential users of the tool has been raised the characteristics and process parameters. The parameters to approach the main quantities involved in the system and its limitations. Data from the survey were analyzed by generating a synthesis of all parameters identified for the development of the next phases. In conceptual design, was the evolution of the solution through the details of a concept, chosen by proposing alternatives for the generation of concepts. The detail is presented through drawings, according to the guideline of design aided computer based functional structure operating the tool, highlighting the major systems and their configurations. The detail is presented in the executive project and includes two types of analysis: kinematic analysis and structural analysis of the system. In the kinematic analysis are presented two proposals for setting for the air motor to be used in the tool. The proposals are exposed through the assembly drawings, exploded drawings and graphics of the parameters of the air motor for each of the configurations adopted. This stage is also shown a prototype. The project results are obtained by performing test bench and field tests to confirm the established parameters. Completing the life cycle of the project, propose to the changing trends, and review possible improvements to the tool. The conclusions of the study are based on the results presented in the tests with the tool, the efficiency of the methodology used to develop the design and analysis of compliance with the defined objectives at work.
46

Ferramenta pneumática para movimentação de carrocerias rodoviárias em linhas de montagem / Pneumatic tool to drive road vehicles on assembly lines

Taborda, Gustavo Gomes January 2009 (has links)
Este trabalho apresenta um estudo de caso na indústria de implementos e veículos rodoviários para solução do processo específico de movimentação de veículos e carrocerias rodoviárias nas linhas de montagem. A solução é o desenvolvimento do projeto de uma ferramenta pneumática para atender os parâmetros identificados no processo de movimentação utilizando uma metodologia de projeto. A metodologia adotada é uma composição de modelos sugeridos por autores mostrando uma sequência clara e objetiva do ciclo de vida do projeto, estruturada em quatro fases principais: Projeto Informacional, Projeto Conceitual, Projeto Executivo e Otimização de Projeto. A identificação das informações relevantes ao processo de movimentação dos produtos deu início ao Projeto Informacional. Com a finalidade de conhecer melhor as características dos processos dos potenciais usuários da ferramenta, foram levantadas as características e os parâmetros do processo. Os parâmetros abordam as principais grandezas envolvidas no sistema e suas limitações. Os dados resultantes do levantamento foram analisados gerando uma síntese de todos os parâmetros identificados para o desenvolvimento das próximas fases. No projeto conceitual, houve a evolução da solução através do detalhamento de um conceito, escolhido mediante a proposição de alternativas durante a geração de conceitos. O detalhamento é apresentado através de desenhos, segundo a diretriz de projeto orientado ao computador, com base na estrutura funcional de funcionamento da ferramenta, salientando os principais sistemas e suas configurações. Os dimensionamentos são apresentados no projeto executivo e contemplam dois tipos de análise: a análise cinemática e a análise estrutural do sistema. Na análise cinemática são apresentadas duas propostas de configuração para o motor pneumático que será utilizado na ferramenta. As propostas são expostas através de desenhos de montagem, desenhos explodidos e gráficos dos parâmetros do motor pneumático para cada uma das configurações adotadas. Nesta fase também é mostrada a construção do protótipo. Os resultados do projeto são obtidos através da realização de teste em bancada e em campo para confirmação dos parâmetros estabelecidos. Completando o ciclo de vida do projeto, propõem-se as tendências evolutivas, analisando as possíveis melhorias para a ferramenta. As conclusões do trabalho são baseadas nos resultados apresentados nos testes realizados com a ferramenta, na eficiência da metodologia adotada para o desenvolvimento do projeto e na análise do cumprimento dos objetivos definidos no trabalho. / This paper presents a case study in industry of road road vehicles for solution of the specific handling of road vehicles and truck trailers in assembly lines. The solution is to develop the design of a pneumatic tool to meet the criteria identified in the move process using a design methodology. The methodology used is a composite of models suggested by the authors showed a clear sequence and objective of the life cycle of the project, divided into four main phases: Informational Design, Conceptual Design, Executive Design and Optimization Project. The identification of information relevant to the process of transferring products initiated the Informational Design. In order to better understand the nature of the processes of potential users of the tool has been raised the characteristics and process parameters. The parameters to approach the main quantities involved in the system and its limitations. Data from the survey were analyzed by generating a synthesis of all parameters identified for the development of the next phases. In conceptual design, was the evolution of the solution through the details of a concept, chosen by proposing alternatives for the generation of concepts. The detail is presented through drawings, according to the guideline of design aided computer based functional structure operating the tool, highlighting the major systems and their configurations. The detail is presented in the executive project and includes two types of analysis: kinematic analysis and structural analysis of the system. In the kinematic analysis are presented two proposals for setting for the air motor to be used in the tool. The proposals are exposed through the assembly drawings, exploded drawings and graphics of the parameters of the air motor for each of the configurations adopted. This stage is also shown a prototype. The project results are obtained by performing test bench and field tests to confirm the established parameters. Completing the life cycle of the project, propose to the changing trends, and review possible improvements to the tool. The conclusions of the study are based on the results presented in the tests with the tool, the efficiency of the methodology used to develop the design and analysis of compliance with the defined objectives at work.
47

Ferramenta pneumática para movimentação de carrocerias rodoviárias em linhas de montagem / Pneumatic tool to drive road vehicles on assembly lines

Taborda, Gustavo Gomes January 2009 (has links)
Este trabalho apresenta um estudo de caso na indústria de implementos e veículos rodoviários para solução do processo específico de movimentação de veículos e carrocerias rodoviárias nas linhas de montagem. A solução é o desenvolvimento do projeto de uma ferramenta pneumática para atender os parâmetros identificados no processo de movimentação utilizando uma metodologia de projeto. A metodologia adotada é uma composição de modelos sugeridos por autores mostrando uma sequência clara e objetiva do ciclo de vida do projeto, estruturada em quatro fases principais: Projeto Informacional, Projeto Conceitual, Projeto Executivo e Otimização de Projeto. A identificação das informações relevantes ao processo de movimentação dos produtos deu início ao Projeto Informacional. Com a finalidade de conhecer melhor as características dos processos dos potenciais usuários da ferramenta, foram levantadas as características e os parâmetros do processo. Os parâmetros abordam as principais grandezas envolvidas no sistema e suas limitações. Os dados resultantes do levantamento foram analisados gerando uma síntese de todos os parâmetros identificados para o desenvolvimento das próximas fases. No projeto conceitual, houve a evolução da solução através do detalhamento de um conceito, escolhido mediante a proposição de alternativas durante a geração de conceitos. O detalhamento é apresentado através de desenhos, segundo a diretriz de projeto orientado ao computador, com base na estrutura funcional de funcionamento da ferramenta, salientando os principais sistemas e suas configurações. Os dimensionamentos são apresentados no projeto executivo e contemplam dois tipos de análise: a análise cinemática e a análise estrutural do sistema. Na análise cinemática são apresentadas duas propostas de configuração para o motor pneumático que será utilizado na ferramenta. As propostas são expostas através de desenhos de montagem, desenhos explodidos e gráficos dos parâmetros do motor pneumático para cada uma das configurações adotadas. Nesta fase também é mostrada a construção do protótipo. Os resultados do projeto são obtidos através da realização de teste em bancada e em campo para confirmação dos parâmetros estabelecidos. Completando o ciclo de vida do projeto, propõem-se as tendências evolutivas, analisando as possíveis melhorias para a ferramenta. As conclusões do trabalho são baseadas nos resultados apresentados nos testes realizados com a ferramenta, na eficiência da metodologia adotada para o desenvolvimento do projeto e na análise do cumprimento dos objetivos definidos no trabalho. / This paper presents a case study in industry of road road vehicles for solution of the specific handling of road vehicles and truck trailers in assembly lines. The solution is to develop the design of a pneumatic tool to meet the criteria identified in the move process using a design methodology. The methodology used is a composite of models suggested by the authors showed a clear sequence and objective of the life cycle of the project, divided into four main phases: Informational Design, Conceptual Design, Executive Design and Optimization Project. The identification of information relevant to the process of transferring products initiated the Informational Design. In order to better understand the nature of the processes of potential users of the tool has been raised the characteristics and process parameters. The parameters to approach the main quantities involved in the system and its limitations. Data from the survey were analyzed by generating a synthesis of all parameters identified for the development of the next phases. In conceptual design, was the evolution of the solution through the details of a concept, chosen by proposing alternatives for the generation of concepts. The detail is presented through drawings, according to the guideline of design aided computer based functional structure operating the tool, highlighting the major systems and their configurations. The detail is presented in the executive project and includes two types of analysis: kinematic analysis and structural analysis of the system. In the kinematic analysis are presented two proposals for setting for the air motor to be used in the tool. The proposals are exposed through the assembly drawings, exploded drawings and graphics of the parameters of the air motor for each of the configurations adopted. This stage is also shown a prototype. The project results are obtained by performing test bench and field tests to confirm the established parameters. Completing the life cycle of the project, propose to the changing trends, and review possible improvements to the tool. The conclusions of the study are based on the results presented in the tests with the tool, the efficiency of the methodology used to develop the design and analysis of compliance with the defined objectives at work.
48

A new type of walking machine

Ingram, Anthony James 10 June 2008 (has links)
This thesis introduces a new type of walking machine that appears promising due to its relative simplicity and efficiency. After an introduction to a selection of previous walking machines, the new machine’s history, advantages, operation and a method for solving its kinematics are given. Early attempts to optimize the mechanism to a range of criteria are described and their shortfalls exposed. A second attempt to optimize the leg geometry by genetic algorithm is detailed and the results of this search discussed. A mechanics model of a hypothetical machine is developed from first principles and the implications of the analysis described. Stability limits and tractive abilities of the machine are explored. A method for determining the loads on the links that constitute the leg and the vehicle chassis is given. A series of prototypes has been constructed and discussions of these machines are given. The most recent prototype is used in a pair of experiments to validate the kinematic and kinetic models. The experimental method, a statistical analysis of results and a discussion are provided for each. The thesis concludes by considering what work remains to be done before a practical cargo carrying transport walking machine can be designed. / Prof. A.L. Nel
49

A systematic approach in product development of industrial processing equipment

Vuza, Simo S. 25 November 2013 (has links)
M.Phil. (Electrical & Electronic Engineering Science) / The need to industrialise South Africa has been an effort of government to increase manufacturing and Gross Domestic Products (GDP) while also creating decent work. Manufacturing industry has been striking with organisations closing and moving. Organisations have been established and fail to compete in the market due to lack of expertise to produce products that meet the customer`s requirements. Due to the opportunities of industrialisation in Africa the focus to develop equipment for these industries is necessary. This research objective is to develop a Systematic Approach of Product Development for Industrial Processing Equipment manufacturers that supply various organisations. The research will respond to the following question while also defining the development process:-  Will product development be helpful in industrialising South Africa and building sustainable manufacturing businesses?  Define a process feedback diagram of a systematic approach of product development to be used by industrial processing equipment? The research is done with the use of literature review form published sources which is validated by survey questions that were sent to sustainable successful organizations that supply industrial equipment. The research finding demonstrates the success phases and steps to be followed when developing product. The phases and their steps are;- 1. Marketing phase stages are Identifying Market Opportunities, Evaluating Potential Markets, Identifying Customer`s Needs and Product specification 2. Concept Development phase stages are system engineering for requirements identification & allocations, Internal & external Search of solution, concept selection and concept testing 3. System Level Design phase stages is Product Architecture 4. Detailed Design Phase stages are industrial design and design for manufacturing 5. Refinement and testing phase stages are designing for reliability, prototyping and testing. These are the phases the research focused on. The Survey revealed that success sustainable organisation have been using product development, marketing and system engineering methodologies as one of their common weapon to stay in business and grow in today’s competitive market place. This systematic approach process feedback diagram in product development has a lot of phase overlap. All phases interact even though there is still a feed process from one phase to the next. The process happens concurrently to ensure that all stages are considered at an earlier stage
50

The optimal design of a planar Stewart platform for prescribed machining tasks

Smit, Willem Jacobus 12 January 2007 (has links)
Recently parallel platforms, also known as Stewart platforms, have been the subject of much active research because of their distinct advantages over serially linked manipulators. Parallel platforms may have a great impact, especially in the field of machine tools. Parallel platforms are however, not yet commonly used as machine tools. The main reason for this is the lack of a general and rationally based design system that is also easily implementable. The availability of such a system will allow for the set-up of a platform so that, not only will the task be executable, but it will also be performed in an optimum manner according to a criterion specified by the user. This study proposes an easy to use methodology that may by applied to the optimum design of planar parallel platforms for machining applications. The design methodology presented here is based on mathematical optimization. This approach is simple and intuitive, and all the most important design criteria can be implemented, in some mathematical form, in the application of the proposed optimization methodology. Six possible design variables are defined, all related to the physical dimensions and placement of the platform for a prescribed task. Different platform designs are studied by using different combinations of design variables, where some design variables are fixed at specific values while the remaining design variables are allowed to vary. Two types of design constraints are considered, namely geometrical constraints that specify physical bounds on the platform size and placement, and secondly, limits on the maximum and minimum allowable actuator leg lengths. The platform design is optimized according to a prescribed criterion. Two design criteria, also called cost functions, are considered in this study. The first is the minimization of the actuator forces as the manipulator executes a prescribed task. The actuator forces are calculated by means of a dynamical analysis software package, DADS. The other design criterion is the maximization of the so-called quality index over the prescribed tool path. The success of mathematical design optimization depends largely on the optimization algorithm that is used to solve the minimization problem. It is shown in this study that the minimization of the actuator forces is a difficult problem to solve by mathematical optimization. Important reasons for this are that some of the cost functions considered here have discontinuities in their gradients with respect to the design variables, and that they are also highly non-convex and non¬quadratic. Another difficulty is the presence of numerical noise superimposed on the cost functions. For this reasons the robust and reliable LFOPC optimization algorithm, of Snyman was used. This method, although relatively slow to converge, was highly successful in solving the various design optimization problems. Because of the slow convergence of the method and the computational cost of evaluating the actuator force cost function and gradients when many design variables are involved, it was decided to attempt to speed up convergence by the use of an approximation method. The approximation algorithm. Dynamic-Q also proposed by Snyman, was selected and its application illustrated by solving a design problem with many design variables. This algorithm quickly converged to an acceptable optimum design. The main conclusion of this study is that the design methodology proposed here can successfully be applied to the design of planar Stewart platforms and may easily be extended to also apply to spatial Stewart platforms. This methodology solves difficult design problems that are inherent to the design of parallel manipulators. Its future implementation in a more comprehensive design and operating system for Stewart platforms to be used for machining tasks is therefore imperative. / Dissertation (M Eng (Mechanical Engineering))--University of Pretoria, 2007. / Mechanical and Aeronautical Engineering / unrestricted

Page generated in 0.0511 seconds