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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.
1

Multiparty interactions in dependable distributed systems

Zorzo, Avelino Francisco January 1999 (has links)
With the expansion of computer networks, activities involving computer communication are becoming more and more distributed. Such distribution can include processing, control, data, network management, and security. Although distribution can improve the reliability of a system by replicating components, sometimes an increase in distribution can introduce some undesirable faults. To reduce the risks of introducing, and to improve the chances of removing and tolerating faults when distributing applications, it is important that distributed systems are implemented in an organized way. As in sequential programming, complexity in distributed, in particular parallel, program development can be managed by providing appropriate programming language constructs. Language constructs can help both by supporting encapsulation so as to prevent unwanted interactions between program components and by providing higher-level abstractions that reduce programmer effort by allowing compilers to handle mundane, error-prone aspects of parallel program implementation. A language construct that supports encapsulation of interactions between multiple parties (objects or processes) is referred in the literature as multiparty interaction. In a multiparty interaction, several parties somehow "come together" to produce an intermediate and temporary combined state, use this state to execute some activity, and then leave the interaction and continue their normal execution. There has been a lot of work in the past years on multiparty interaction, but most of it has been concerned with synchronisation, or handshaking, between parties rather than the encapsulation of several activities executed in parallel by the interaction participants. The programmer is therefore left responsible for ensuring that the processes involved in a cooperative activity do not interfere with, or suffer interference from, other processes not involved in the activity. Furthermore, none of this work has discussed the provision of features that would facilitate the design of multiparty interactions that are expected to cope with faults - whether in the environment that the computer system has to deal with, in the operation of the underlying computer hardware or software, or in the design of the processes that are involved in the interaction. In this thesis the concept of multiparty interaction is integrated with the concept of exception handling in concurrent activities. The final result is a language in which the concept of multiparty interaction is extended by providing it with a mechanism to handle concurrent exceptions. This extended concept is called dependable multiparty interaction. The features and requirements for multiparty interaction and exception handling provided in a set of languages surveyed in this thesis, are integrated to describe the new dependable multiparty interaction construct. Additionally, object-oriented architectures for dependable multiparty interactions are described, and a full implementation of one of the architectures is provided. This implementation is then applied to a set of case studies. The case studies show how dependable multiparty interactions can be used to design and implement a safety-critical system, a multiparty programming abstraction, and a parallel computation model.
2

Práticas e ganhos na implantação e sustentabilidade de fluxo contínuo em ambientes Lean: um estudo de caso / Practices and gains on the implementation and sustainability of a Continuous Flow in Lean environments: a case study

Guilherme Valadão de Brito Soares 13 February 2017 (has links)
As práticas e ferramentas de Lean Production já foram e vêm sendo implantadas em várias empresas dos mais diversos setores. Porém, muitas vezes tais implantações não atingem o resultado esperado. O que se observa é que o processo de implantação de práticas e ferramentas utilizadas em ambientes Lean, foca, em grande parte das vezes, na implantação de algumas ferramentas, tais como o sistema kanban ou 5S, deixando de lado a busca constante por um processo que funcione com estoque zero e sem defeitos. Tal cenário, mesmo sendo inatingível no curto ou médio prazo para grande parte das empresas é, porém, a essência do sistema de produção originado na Toyota. Esta pesquisa identifica que a implantação do fluxo contínuo é fundamental durante as implantações de práticas de Lean Production por embasar essa busca constante pela melhoria do fluxo de produção, visando sempre a remoção dos desperdícios presentes ao longo do fluxo. Por meio da realização de uma Revisão Bibliográfica exploratória são identificadas também as práticas e ferramentas que têm a sua implantação relatada com o objetivo de auxiliar a implantação ou dar sustentabilidade a um fluxo contínuo. Um estudo de caso relata a implantação de fluxo contínuo em um processo de costura com a utilização de células de produção, mostrando ainda quais outras práticas e ferramentas foram implantadas. O resultado encontrado foi que as práticas e ferramentas mais utilizadas para auxiliar a implantação e sustentabilidade de um fluxo contínuo são o takt time, balanceamento das operações, Mapeamento de Fluxo de Valor (MFV), layout celular, trabalho padronizado e sistemas puxados. Os principais ganhos identificados como resultado da implantação do fluxo contínuo e de práticas e ferramentas para auxiliá-lo em ambientes de lean production são a redução do lead time de produção, redução do work in process, aumento de produtividade, redução da área utilizada pela produção, redução do custo de produção e a redução do tempo gasto com atividades que não agregam valor ao produto. A principal dificuldade identificada para a implantação do fluxo contínuo foi a aceitação da equipe de produção, principalmente durante o início das operações após as implantações. O apoio dos Supervisores, Gerentes e Diretores das empresas se mostra fundamental para o sucesso de tal empreitada. / The practices and tools of Lean Production were and are being implemented in many companies of the most diverse sectors. However, many times such implementations do not achieve the expected result. What is observed is that the implementation process of the practices and tools used in Lean environments in a great part of the time focus on the implementation of some tools such as kanban system or 5S, keeping aside the constant search for a process that works with zero stock and with no defects. Such scenario, even being unachievable in a short and medium term for great part of the companies is, however, the essence of the production system started at Toyota. This paper identifies that the implementation of continuous flow is fundamental during the implementation of Lean Production practices for supporting this constant search for improvement of the production flow, always aiming the removal of the waste present along the flow. Through a Literature Review, are also identified the practices and tools that have its implementation reported with the target of supporting the implementation or sustain a continuous flow. A case study reports the implementation of continuous flow in a stitching process through the use of production cells, showing also what other practices and tools were implemented. The result found was that the practices and tools most used to support the implementation and sustainability of a continuous flow are takt time, workload balancing, Value Stream Mapping (VSM), cellular layout, standardized work and pull system. The main gains identified as a result of the implementation of the continuous flow and practices and tools to support it in Lean Production environments are the reduction of the production lead time, reduction of work in process, increase of productivity, decrease of the area used by the production, reduction of production cost and reduction of the time spent with non-add value activities. The main difficulty identified for the implementation of a continuous flow was the acceptance of the production team, mainly during the beginning of the operations right after the implementation. The support of Supervisors, Managers and Directors of the companies reveals fundamental for the success of this endeavor.
3

Práticas e ganhos na implantação e sustentabilidade de fluxo contínuo em ambientes Lean: um estudo de caso / Practices and gains on the implementation and sustainability of a Continuous Flow in Lean environments: a case study

Soares, Guilherme Valadão de Brito 13 February 2017 (has links)
As práticas e ferramentas de Lean Production já foram e vêm sendo implantadas em várias empresas dos mais diversos setores. Porém, muitas vezes tais implantações não atingem o resultado esperado. O que se observa é que o processo de implantação de práticas e ferramentas utilizadas em ambientes Lean, foca, em grande parte das vezes, na implantação de algumas ferramentas, tais como o sistema kanban ou 5S, deixando de lado a busca constante por um processo que funcione com estoque zero e sem defeitos. Tal cenário, mesmo sendo inatingível no curto ou médio prazo para grande parte das empresas é, porém, a essência do sistema de produção originado na Toyota. Esta pesquisa identifica que a implantação do fluxo contínuo é fundamental durante as implantações de práticas de Lean Production por embasar essa busca constante pela melhoria do fluxo de produção, visando sempre a remoção dos desperdícios presentes ao longo do fluxo. Por meio da realização de uma Revisão Bibliográfica exploratória são identificadas também as práticas e ferramentas que têm a sua implantação relatada com o objetivo de auxiliar a implantação ou dar sustentabilidade a um fluxo contínuo. Um estudo de caso relata a implantação de fluxo contínuo em um processo de costura com a utilização de células de produção, mostrando ainda quais outras práticas e ferramentas foram implantadas. O resultado encontrado foi que as práticas e ferramentas mais utilizadas para auxiliar a implantação e sustentabilidade de um fluxo contínuo são o takt time, balanceamento das operações, Mapeamento de Fluxo de Valor (MFV), layout celular, trabalho padronizado e sistemas puxados. Os principais ganhos identificados como resultado da implantação do fluxo contínuo e de práticas e ferramentas para auxiliá-lo em ambientes de lean production são a redução do lead time de produção, redução do work in process, aumento de produtividade, redução da área utilizada pela produção, redução do custo de produção e a redução do tempo gasto com atividades que não agregam valor ao produto. A principal dificuldade identificada para a implantação do fluxo contínuo foi a aceitação da equipe de produção, principalmente durante o início das operações após as implantações. O apoio dos Supervisores, Gerentes e Diretores das empresas se mostra fundamental para o sucesso de tal empreitada. / The practices and tools of Lean Production were and are being implemented in many companies of the most diverse sectors. However, many times such implementations do not achieve the expected result. What is observed is that the implementation process of the practices and tools used in Lean environments in a great part of the time focus on the implementation of some tools such as kanban system or 5S, keeping aside the constant search for a process that works with zero stock and with no defects. Such scenario, even being unachievable in a short and medium term for great part of the companies is, however, the essence of the production system started at Toyota. This paper identifies that the implementation of continuous flow is fundamental during the implementation of Lean Production practices for supporting this constant search for improvement of the production flow, always aiming the removal of the waste present along the flow. Through a Literature Review, are also identified the practices and tools that have its implementation reported with the target of supporting the implementation or sustain a continuous flow. A case study reports the implementation of continuous flow in a stitching process through the use of production cells, showing also what other practices and tools were implemented. The result found was that the practices and tools most used to support the implementation and sustainability of a continuous flow are takt time, workload balancing, Value Stream Mapping (VSM), cellular layout, standardized work and pull system. The main gains identified as a result of the implementation of the continuous flow and practices and tools to support it in Lean Production environments are the reduction of the production lead time, reduction of work in process, increase of productivity, decrease of the area used by the production, reduction of production cost and reduction of the time spent with non-add value activities. The main difficulty identified for the implementation of a continuous flow was the acceptance of the production team, mainly during the beginning of the operations right after the implementation. The support of Supervisors, Managers and Directors of the companies reveals fundamental for the success of this endeavor.
4

Proposta de arquitetura para reconfigurar tarefas em célula flexível de produção

Donizeti Bíscaro 24 November 2011 (has links)
Este trabalho apresenta proposta de arquitetura orientada para um sistema que utiliza a interface gráfica como elemento principal para reconfigurar a seqüência de tarefas que podem ser executadas por uma célula flexível de produção. É dada especial atenção na elaboração dos componentes dessa interface, pois as corretas definições e operações desses componentes são condições determinantes para se alcançar êxito no uso do sistema. A validação da funcionalidade dessa interface é obtida por meio da realização de testes em um protótipo, que adota os elementos básicos previstos na mencionada arquitetura. Os resultados positivos observados nesses testes indicam que o sistema proposto é adequado para a finalidade a qual se destina. / This work presents a proposal for a system-oriented architecture that uses the graphical interface as the main element to reconfigure the sequence of tasks that can be performed by a flexible production cell. Particular attention is given in the preparation of the components of this interface, because the correct settings and operations of these components are critical to achieving success in the use of the system. Validation of the functionality of this interface is obtained by means of conducting tests on a prototype, which adopts the basic elements contained in the mentioned architecture. The positive results observed in these tests indicate that the proposed system is suitable for the purpose for which it is intended.
5

Production Cell Simulation and Control Software

Shynkariuk, Oleksandr January 2013 (has links)
Control software plays an important role in industrial automation. Several domainspecific languages for control software implementation were designed and accepted in industry. Structured Text (ST)[1] is one of these languages. It is standardized by IEC 61131-3 standard and designed for programmable logic controllers. In this thesis two implementations of control software were developed: Java implementation as a reference model, and ST implementation as a test scenario for ST to C compiler. The functionality of both implementations was compared using the simulation model. It was concluded that resulting ST control software provides the same functionality as its reference model.
6

Implementace prvků automatizace do výrobního procesu v Poclain Hydraulics s.r.o. / Implementation of automation elements within machining processes in Poclain Hydraulics s.r.o.

Ciba, Martin January 2017 (has links)
Cieľom práce je zanalyzovať aktuálny výrobný proces dráh pre hydraulické motory a navrhnúť jeho optimalizáciu. Na základe analýzy výrobného procesu a prieskumu dostupných možností automatizácie sú vytvorené viaceré návrhy automatizovanej výrobnej bunky. Práca sa zaoberá technicko-ekonomickou analýzou projektu a porovnáva viaceré možnosti automatizácie výroby.
7

Antibody-mediated rejection of arterialised venous allografts is inhibited by immunosuppression in rats: Antibody-mediated rejection of arterialised venousallografts is inhibited by immunosuppression in rats

Splith, Katrin, Jonas, Sven January 2014 (has links)
We determined in a rat model (1) the presence and dynamics of alloantibodies recognizing MHC complexes on quiescent Brown-Norway (BN) splenic cells in the sera of Lewis (LEW) recipients of Brown-Norway iliolumbar vein grafts under tacrolimus immunosuppression; and (2) the presence of immunoglobulins in the wall of acute rejected vein allografts.
8

Sintonia do filtro de Kalman para medição indireta das variáveis de estado no banho eletrolitico / Tunning of the Filter of Kalman for indirect measurement of the variable of state in the electrolytic bath

Braga, Carlos Augusto Pereira 07 April 2008 (has links)
Made available in DSpace on 2016-08-17T14:52:48Z (GMT). No. of bitstreams: 1 Carlos Augusto Pereira Braga.pdf: 1145854 bytes, checksum: 8898d3084e223e4e9ad52a8aa7363b01 (MD5) Previous issue date: 2008-04-07 / A tunning model for Kalman filter based on QR duality principle is presented to measure the state variables of the electrolytic bath in aluminium production cells. The main goal is to establish a set of filter gains that better represents the percentual of alumina in the bath. The filter bandwidth tunning is performed by increasing or decreasing the filter bandpass from the Q and R variations. The design and analysis of the Q and R covariance matrices are performed to find a pattern of the resistance variations that could be associated with the alumina concentration in the bath. The technical solution encloses on-line evaluation of the Kalman filter in order to prove its capableness of response when used to control real production cells. The Standard Kalman is coded upon a scalar form to reduce the use of computing resources when the filter is processed. The line current and pot voltage are directly read from the hardware interface and then converted in a third variable, the resistance, which is used to infer the alumina concentration in the bath. Moreover, the filter implementation goes in the direction of practical aspects limits of the indirect measurement system implementations, its robustness is appraised by observability, roundo® and modeling errors. / O controle da concentração de alumina no banho de cubas eletroliticas é de vital importância para um rendimento eficiente do processo de produção de aluminio. Este controle tem por objetivo promover, em uma visão macro, um retorno justificável perante ao planejamento global das metas de produção de uma fábrica de aluminio. O desenvolvimento de uma metodologia baseada no ajuste dos ganhos de um filtro tipo Kalman Padrão é o principal enfoque cientifico e tecnológico desta pesquisa. A sintese da metodologia é a implementação do filtro de Kalman Padrão e Escalar em um computador que controla a quantidade de alumina no banho eletrolitico. Considera-se as restrições de software e de hardware na implantação do algoritmo de Kalman no sistema que executa o controle de processo por computador. Desenvolve-se um modelo de sintonia do filtro de Kalman utilizando-se o principio da dualidade das matrizes Q e R. O objetivo é estabelecer um conjunto de ganhos que representem da melhor forma a quantidade de alumina dentro da cuba. Assim, faz-se uma análise considerando-se mudanças nas matrizes Q e R, e apresenta-se os resultados obtidos. Analisa-se a largura de banda do filtro, verificando-se diminuição ou aumento de banda na medida que as matrizes Q e R sofrem alterações em seus elementos. As estratégias de monitoramento são verificadas para diversas situações de operação(dinâmica) da planta, e as variações paramétricas do modelo são levadas em consideração para garantirmos uma operação robusta e estável do filtro. O desempenho do filtro é verificado em paralelo com um sistema de filtragem e de controle historicamente utilizados na estimação do percentual de alumina no banho eletrolitico.
9

Konstrukce transportního vozíku s robotem nebo nosičem palet / Design of transfer carriage equipped with robot or pallete holder

Tatíček, Vojtěch January 2019 (has links)
The aim of this work was to design the construction of transport equipment under industrial robot, pallet holder or other equipment. This manipulation device can be moved in one axis on a rigid guide. The device is designed for use in a linear manufacturing system for handling workpieces and tools. It is capable of operating two rows of machines when it is placed in the middle. The main function of this device is to extend the workspace to the carried devices. This type of construction can be used in combination with an industrial robot for other technological tasks such as welding or light machining. The main parts of this device include statically mounted beds that can be stacked behind each other to form optionally long conveyor paths and a positioning plate that moves along the path formed by these beds. An industrial robot, pallet holder or other device is attached to this positioning plate. In addition to the design itself, the thesis also includes a thorough research of the issue, further possibilities of solution in the form of concepts, verification of the structure by means of calculations and simulations and implementation of the solution into a specific production cell.

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