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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.
71

Análise da variabilidade de vibração em atuadores elétricos

Rocha, Clayton Gilnei Martins January 2016 (has links)
Em sistemas modernos de manutenção inteligente a qualidade de uma máquina ou equipamento depende do suporte que é fornecido junto com esse produto, com a confiabilidade e segurança na utilização do mesmo. Estas exigências, por vezes, não são cumpridas e podem estar indisponíveis em algumas máquinas. Este trabalho descreve uma abordagem utilizando sinais de vibração coletados em tempo real com falhas como estudo preliminar para uma abordagem mais profunda como estudo dametodologia de testes de vida acelerado para auxiliar durante a fase de vida operacional permitindo ao fabricante a determinação dos ciclos de vida do produto. A abordagem proposta construída em cima de experiências anteriores em desenvolvimento no projeto Integração de Sistemas Inteligentes de Manutenção e Cadeia de Fornecimento de Peças Sobressalentes. O objetivo deste trabalho é apresentar resultados preliminares analisando a variabilidade das assinaturas de falhas das engrenagens danificadas de maneira a permitir a identificação dos ciclos de vida do produto para partes específicas de um atuador elétrico. / In modern systems of intelligent maintenance the quality of a machine or equipment depends on the support that comes with this product, with the reliability and safety in the use of it. These requirements are sometimes not met and may be unavailable on some machines. This paper describes an approach using vibration signals collected in real-time with faults as a preliminary study for a deeper approach with the study of the methodology of accelerated life tests to assist during the operational life stage allowing the manufacturer the determination of the life cycles of product. The proposed approach built on previous experiences under development in the project Integration of Intelligent Systems of Maintenance and Chain of Supply of Spares. The objective of this work is to present preliminary results analyzing the variability of failure signatures of the damaged gears in order to allow the identification of product life cycles for specific parts of an electric actuator.
72

Using the Collective System Design Approach to Facilitate a Sustainable Manufacturing System

Shahab Shah (5931203) 07 May 2019 (has links)
<div>Reviewing the literature verifies that manufacturing industries fall short of the required sustainable criteria in the system design.</div><div>One of the leading reasons behind such a failure refers to the lack of an effective system design's knowledge toward the selected solutions by benchmarking.</div><div>The Collective System Design (CSD) approach provides a countermeasure for this shortcoming by starting the design approach with a collective agreement upon the external and internal customer needs and then choosing the solutions for the system design to achieve those needs. </div><div>The general requirements and solutions to a manufacturing system are covered in the Manufacturing System Design Decomposition (MSDD) in a linear and path-dependent fashion, which is a core derivative of the CSD.</div><div><br></div><div>The CSD application in industrial case studies has been provided in this thesis to elaborate on how the CSD approach assists industries to re-design their systems in a sustainable manner.</div><div>The segregation of the tools and objectives of the system re-design in a path-dependent fashion is guided by the design principles.</div><div>The case studies described how to achieve the external customer needs of product quality, quantity, variety, and on-time delivery with a collaborative work inside the plant. </div><div>This collaboration was built up by defining the customer-supplier connection inside the plant.</div><div>Cell re-design and balancing of operations with a well-defined standard work is also elaborated in this research to help produce what is needed to be shipped today with the least amount of waste in the system.</div><div>The after system redesign MSDD questionnaire analysis at these industries have shown that the industries successfully satisfied their system needs in a sustainable manner. </div><div><br></div><div>In those case studies, an internal customer need for a safe working environment was also brought to light and the CSD approach was introduced and applied to achieve the associated requirements of safety. </div><div>As the original MSDD lacked the requirements and solutions for the safety component, an updated version of the MSDD has been proposed to incorporate </div><div>the safety branch to the MSDD.</div><div>In addition, some enhancements to the current version of the MSDD have been made for a clearer and more thorough understanding of the system design.</div>
73

Container fleet-sizing for part transportation and storage in the supply chain

Park, SeJoon 06 December 2011 (has links)
This research addresses fleet-sizing for reusable containers that are used for protection, transportation, and storage of parts between a component plant and assembly plant. These reusable containers are often expensive and occupy a large amount of storage space when empty and full. Having a large container fleet comes with higher acquisition, maintenance, and storage costs, but decreases production down time caused by the lack of containers needed for storage. A quantitative model of these trade-offs will permit decision makers to maintain desired production levels at minimum cost. In this dissertation, the relationship between container fleet size and production down time caused by container shortages is researched. Utilizing both theoretical and empirical approaches, two analytical models that include relevant operational parameters and stochastic components are developed. The first is a container fleet sizing model, and the second model estimates production stoppages as a function of container fleet size. The formulas are shown to be accurate and provide decision makers with the tools to better plan and manage specific applications. The formulas also provide general insight into the factors that affect container fleet size and production stoppage due to container shortages. / Graduation date: 2012
74

Order-driven Flexibility Management In Make-to-order Companies With Flexible Shops

Suer, Bekir Ilker 01 November 2009 (has links) (PDF)
In this study, an operational (short term) flexibility management approach is proposed for make-to-order companies with flexible shops. Order Review and Release (ORR) techniques and typical Flexible Manufacturing System (FMS) decisions are combined in this method. The proposed method prepares a shop environment by allocating process and routing flexibility types at different levels to the shop in each production cycle. Variety, volume, and criticality of the part types in the pool and the anticipated orders constitute the main inputs for flexibility allocation. A flexibility management policy is introduced and determination of the proper policy is realized with the integrated utilization of mathematical programming and simulation modeling. An experimental study is performed to investigate the effects of proposed method on a hypothetical flexible shop. Results show that with an appropriate policy, periodical and online flexibility management can be an effective tool to cope with uncertainty in demand if combined with ORR techniques.
75

DEVELOPMENT OF ASSESSMENT CRITERIA FOR RECONFIGURABILITY IN A MANUFACTURING SYSTEM

Banavara Srikanth, Karthik, Shetty, Savin January 2018 (has links)
To survive in the global market the manufacturing companies need to meet the cus-tomer demands quickly and effectively. Therefore, lot of companies are striving to overcome the demand fluctuation and uncertainty. RMS is a concept which handles uncertainty easily by running the product mix and varying the level of volume accord-ing to the requirement. The reconfigurability level of manufacturing system is as-sessed by evaluating the criteria affecting the characteristics of the system.The characteristics of reconfigurability are scalability, customization, convertibility, modularity, integrability and diagnosability. A RMS achieves quick and cost effective changes through customization and convertibility, it handles volume variations through scalability. These characteristics are achieved with the help of modularity and integrability. A detailed assessment of a manufacturing system based on these charac-teristics will indicate its level of reconfigurability. Hence assessment of a manufactur-ing system for reconfigurability becomes necessary in the current turbulent market conditions.This research presents a method to assess the reconfigurability in a manufacturing system. The research is divided into two parts where, in the first part a qualitative as-sessment method is developed, and it is then tested in the second part. The study uses two research methods namely literature review and case study. Based on literature re-view assessment criteria for each characteristic of reconfigurability are listed and an assessment method is developed. The assessment method uses a radar chart to repre-sent the level of reconfigurability. This is supported with a case study where the de-veloped assessment method is tested and validated.
76

Análise da variabilidade de vibração em atuadores elétricos

Rocha, Clayton Gilnei Martins January 2016 (has links)
Em sistemas modernos de manutenção inteligente a qualidade de uma máquina ou equipamento depende do suporte que é fornecido junto com esse produto, com a confiabilidade e segurança na utilização do mesmo. Estas exigências, por vezes, não são cumpridas e podem estar indisponíveis em algumas máquinas. Este trabalho descreve uma abordagem utilizando sinais de vibração coletados em tempo real com falhas como estudo preliminar para uma abordagem mais profunda como estudo dametodologia de testes de vida acelerado para auxiliar durante a fase de vida operacional permitindo ao fabricante a determinação dos ciclos de vida do produto. A abordagem proposta construída em cima de experiências anteriores em desenvolvimento no projeto Integração de Sistemas Inteligentes de Manutenção e Cadeia de Fornecimento de Peças Sobressalentes. O objetivo deste trabalho é apresentar resultados preliminares analisando a variabilidade das assinaturas de falhas das engrenagens danificadas de maneira a permitir a identificação dos ciclos de vida do produto para partes específicas de um atuador elétrico. / In modern systems of intelligent maintenance the quality of a machine or equipment depends on the support that comes with this product, with the reliability and safety in the use of it. These requirements are sometimes not met and may be unavailable on some machines. This paper describes an approach using vibration signals collected in real-time with faults as a preliminary study for a deeper approach with the study of the methodology of accelerated life tests to assist during the operational life stage allowing the manufacturer the determination of the life cycles of product. The proposed approach built on previous experiences under development in the project Integration of Intelligent Systems of Maintenance and Chain of Supply of Spares. The objective of this work is to present preliminary results analyzing the variability of failure signatures of the damaged gears in order to allow the identification of product life cycles for specific parts of an electric actuator.
77

Uma heurística para a programação da produção de sistemas flexíveis de manufatura usando modelagem em redes de Petri.

Maggio, Eduardo Gomes Ribeiro 30 May 2005 (has links)
Made available in DSpace on 2016-06-02T19:05:23Z (GMT). No. of bitstreams: 1 DissEGRM.pdf: 5921557 bytes, checksum: 89005165cd9d839d8283e0713abe1fb8 (MD5) Previous issue date: 2005-05-30 / Financiadora de Estudos e Projetos / The Petri Net based Search has been shown as a promising way to solve Flexible manufacturing Systems (FMS) Scheduling Problem. However, the response time is critical since it s a system with high computational complexity. Focusing the reduction of response time, this work proposes a heuristic for Petri Net based Search to solve FMS Scheduling problem of makespan minimization. Experiments showed improvements on response time reduction comparing with prior works / Abordagens de Busca baseadas em Rede de Petri (PN) têm sido mostradas como uma forma promissora de resolver o problema da Programação da Produção de Sistemas Flexíveis de Manufatura (FMS). Entretanto, o tempo de resposta é crítico, uma vez que se trata de um sistema de alta complexidade computacional. Focando a redução do tempo de resposta do sistema, este trabalho propõe uma heurística para busca baseada em Rede de Petri para resolver o problema de programação de FMS na minimização do makespan. Experimentos mostraram um avanço na melhoria do tempo de resposta em relação a trabalhos anteriores
78

Método de resolução de deadlocks no controle de produção de sistemas de manufatura automatizados utilizando redes de Petri coloridas

Souza, Wesley Willy Oliveira de 01 July 2011 (has links)
Made available in DSpace on 2016-06-02T19:06:03Z (GMT). No. of bitstreams: 1 4911.pdf: 4490259 bytes, checksum: 94cfbdb804ef2f55cb81e1163b1c6ad4 (MD5) Previous issue date: 2011-07-01 / Universidade Federal de Sao Carlos / Resources sharing is one of the main characteristics of Automated Manufacturing Systems (SMA), this characteristic can be a synonym of advantages but on the other hand it may lead to the problem of deadlock. Several papers have suggested methods and techniques to reduce or eliminate the occurrence of deadlocks in SMA systems. The deadlock resolution strategies suggested in the literature can be classified into the following types: deadlock detection and recovery, deadlock prevention and deadlock avoidance. This work proposes a resolution method for the control of automated manufacturing systems using colored Petri nets, the main goal of the proposed method is to provide a deadlock-free production controller. To model, simulate and implement the technique in a production controller a dedicated software is used to model the Petri Nets. Initially, a model using Colored Petri Nets is proposed, then changes in the model are introduced in order to eliminate the deadlocks, resulting in a Colored Petri net control model of the SMA. Finally the model is implemented in the scenario of a Flexible Manufacturing System for testing and validation of the method. / O Compartilhamento de recursos é uma das principais características dos Sistemas de Manufatura Automatizados (SMA), esta característica pode ser um sinônimo de vantagens, mas por outro lado pode levar ao problema de deadlock. Diversos trabalhos têm sugerido métodos e técnicas para reduzir ou eliminar a ocorrência de deadlocks em SMA. As estratégias de resolução de deadlock sugerido na literatura podem ser classificados nos seguintes tipos: detecção e recuperação de deadlocks, prevenção de deadlocks e de deadlock. Este trabalho propõe um método de resolução para o controle de sistemas de manufatura automatizados utilizando redes de Petri coloridas, o principal objetivo do método proposto é obter um controlador da produção livre de deadlocks. Para modelar, simular e implementar a técnica em um controlador de produção um software dedicado é usado para modelar a rede de Petri. Inicialmente, um modelo usando Redes de Petri Coloridas é proposto, então mudanças são introduzidas, a fim de eliminar os deadlocks, resultando em um modelo de rede de Petri de um SMA livre de deadlock. Finalmente o modelo é implementado no cenário de um Sistema de Manufatura Flexível para testes e validação do método.
79

Redução automatizada de redes de petri baseada em algoritmos genéticos

Bevilaqua, André 26 June 2014 (has links)
Made available in DSpace on 2016-06-02T19:06:15Z (GMT). No. of bitstreams: 1 6263.pdf: 2838494 bytes, checksum: 852261a244b09c47cc828522a799cc8d (MD5) Previous issue date: 2014-06-26 / Petri Net (PN) is a graphical mathematical tool used to create models that provide a formal specification of systems, creating the possibility of running behavior analysis and property verification. PN models can be used to model several system types, for example, Manufacturing Systems. In general, using PN to model systems with too many characteristics cause the so-called state-space explosion problem, in other words, a great element profusion in the model. In order to mitigate the referred problem researchers developed reduction rules to synthetize models. Reduced models maintain original system properties and can be easily analyzed and simulated. A method to automate reduction rules application is proposed on the present research. A Genetic Algorithm heuristic is responsible for applying six reductions rules on Place-Transition Petri Nets given as input. The proposed algorithm, presented as a Matlab toolbox, may contribute when simulating and running property verification methodologies on Petri Net models. / Rede de Petri (RP) é uma ferramenta de modelagem com rigor matemático usada para especificar e formalizar sistemas e suas características. Modelos de RP podem ser avaliados quanto à seu comportamento dinâmico e suas propriedades estruturais. Diversos tipos de modelos podem ser especificados usando RP s, por exemplo, modelos de Sistemas de Manufatura. De maneira geral, modelos de sistemas complexos sofrem do problema da grande profusão de elementos. Esse problema é um limitante para diversas metodologias de verificação de propriedades e simulação de comportamento dinâmico dos modelos. Frequentemente metodologias baseadas em regras de redução são propostas para superar o problema da grande profusão de elementos. O presente trabalho apresenta uma ferramenta para automatizar a aplicação de regras de redução em modelos de RP. Um conjunto de regras foi selecionado para montar uma base de regras de redução e uma heurística baseada em algoritmos genéticos foi criada para aplicar reduções em modelos de RP Lugar-Transição. Os resultados obtidos mostraram que a ferramenta proposta, apresentada como uma toolbox do Matlab, pode ser utilizada para auxiliar no processo de análise, simulação e verificação de propriedades de sistemas modelados por meio de RP s.
80

Análise da variabilidade de vibração em atuadores elétricos

Rocha, Clayton Gilnei Martins January 2016 (has links)
Em sistemas modernos de manutenção inteligente a qualidade de uma máquina ou equipamento depende do suporte que é fornecido junto com esse produto, com a confiabilidade e segurança na utilização do mesmo. Estas exigências, por vezes, não são cumpridas e podem estar indisponíveis em algumas máquinas. Este trabalho descreve uma abordagem utilizando sinais de vibração coletados em tempo real com falhas como estudo preliminar para uma abordagem mais profunda como estudo dametodologia de testes de vida acelerado para auxiliar durante a fase de vida operacional permitindo ao fabricante a determinação dos ciclos de vida do produto. A abordagem proposta construída em cima de experiências anteriores em desenvolvimento no projeto Integração de Sistemas Inteligentes de Manutenção e Cadeia de Fornecimento de Peças Sobressalentes. O objetivo deste trabalho é apresentar resultados preliminares analisando a variabilidade das assinaturas de falhas das engrenagens danificadas de maneira a permitir a identificação dos ciclos de vida do produto para partes específicas de um atuador elétrico. / In modern systems of intelligent maintenance the quality of a machine or equipment depends on the support that comes with this product, with the reliability and safety in the use of it. These requirements are sometimes not met and may be unavailable on some machines. This paper describes an approach using vibration signals collected in real-time with faults as a preliminary study for a deeper approach with the study of the methodology of accelerated life tests to assist during the operational life stage allowing the manufacturer the determination of the life cycles of product. The proposed approach built on previous experiences under development in the project Integration of Intelligent Systems of Maintenance and Chain of Supply of Spares. The objective of this work is to present preliminary results analyzing the variability of failure signatures of the damaged gears in order to allow the identification of product life cycles for specific parts of an electric actuator.

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