Thesis (Ph. D. in Computer Science)--Vanderbilt University, Dec. 2005. / Title from title screen. Includes bibliographical references.

A new algorithm is developed for setting WIP level in production lines. It is a pull policy that determines when to authorize a job to be processed. Dynamic information in the system such as machine failures and repairs, and demand variations are taken into consideration to provide an efficient method to dynamically determine the WIP level. Two types of production lines are examined in this paper. The first is production lines which have few random interruptions and the second production line is exposed to frequent interruptions. Experiment results from these two types of production lines illustrate that the new algorithm generates higher service level with lower WIP compared to the CONWIP policy. In addition, the superiority of the new algorithm is more significant when the production line is exposed to frequent random interruptions. / Singapore-MIT Alliance (SMA)

Power industries in transmission and distribution level are obligated to maintain and replace their electrical equipment. Maintaining the quality and continuity of supply is their priority to avoid customers' complaints and financial penalisation. Live-line working as one of the most important methods of maintenance has been used since the 1900s where the new methods in 1960s made the live-line workers enabled to work on the higher voltage levels up to 800kV. Various industries adopt different techniques to calculate the minimum approach distance (MAD) during the live-line work. A suitable method reduces the risk to live-line workers and provides adequate safety distances between the live parts and linesmen. Therefore, setting an appropriate safety distance between the linesmen and live parts ensures the safety of the workers and minimise the risk of flashover. In this thesis, different methods of calculation of the minimum approach distance are described, and results from overvoltage simulations are used as an input to the methodology outlined in IEC 61472. Also, this thesis highlights and investigates the impact of a range of factors within 400kV transmission line on the minimum approach distance (MAD). Factors examined include the time to crest of the overvoltage (wave shape), the fault type, the probability of occurrence of each type of fault, fault level and the type of overhead line and towers. Furthermore, the minimum approach distances and also associated risk due to each factor and scenario have been calculated. The calculated risk in this thesis presents the risk of failure of a gap against the switching overvoltages due to the simulation of sources of overvoltage. A new set of estimated equations is developed to consider the influence of wave shape in the calculation of the minimum approach distance (MAD). This thesis does not propose a method to replace the international standards, but it could be used in many situations including where utility companies wish to develop a complete understanding of the risk associated with live-line working. Calculation of the minimum approach distance (MAD) within the National Grid UK is based on the methodology described in the IEC 61472, whereas EDF Energy uses the IEEE method to calculate the minimum approach distance. The choice of a smaller / larger minimum approach distance (MAD) using different methods will have an impact on the risk associated with live-line working. Previous works intend to investigate the magnitude of switching overvoltages on one part of a network and calculate the appropriate minimum approach distance for the work in that section. This work is based on the examination of the switching overvoltages under the worst case scenarios. As a result, the simulated overvoltages in this work are higher than expected overvoltages in National Grid network. Also as in practice, the magnitude of switching overvoltages in National Grid network is controlled by different protections equipment therefore, the simulated results and the calculated minimum approach distances in this work are very conservative.

Boston University. University Professors Program Senior theses. / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / 2031-01-02

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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências da Educação, Programa de Pós-Graduação em Educação, Florianópolis, 2016. / Made available in DSpace on 2017-04-18T04:12:11Z (GMT). No. of bitstreams: 1 344702.pdf: 3199974 bytes, checksum: 0d217d31f5201c5eb6bbdef4effa6472 (MD5) Previous issue date: 2016 / Esta dissertação se fundamenta na perspectiva crítica que defende a não neutralidade das tecnologias na abordagem cibercriticista defendida por Rüdiger. E experimenta uma prática pedagógica amparada na mídia-educação para promover uma apropriação crítica e criativa das TIC na educação, como conteúdo e como ferramenta pedagógica. A formação crítica pode estar pautada em atitudes como autoria e cooperação fomentadas pelas redes sociais e projetos criativos mediados pelo professor, como proposta para superação da pedagogia da transmissão. A pesquisa buscou identificar fatores e circunstâncias (o que pode promover) para o desenvolvimento de autoria e cooperação em atividade pedagógica no Facebook. Trata-se de um estudo de caso com observação participante de uma experiência de apropriação do Facebook (grupo de estudos) na preparação de alunos formandos do ensino médio para os exames do ENEM no ano de 2015, realizada em uma escola de educação básica da rede pública estadual de Santa Catarina, situada no município de Leoberto Leal. A partir de coleta de dados (questionários e conteúdos publicados), foi utilizado um instrumento de investigação cuja finalidade foi selecionar e definir indicadores para os conceitos de autoria e cooperação a partir do referencial teórico, e desenvolve métricas (evidências) para a análise de conteúdo das trocas comunicativas entre alunos e professores. Os resultados apontam que utilizar redes sociais conservando a lógica conteudista e reprodutivista do livro didático, reduzindo o aluno a olhar, ouvir, copiar e prestar contas, não dará conta de formar sujeitos críticos imersos da cultura digital. Houve reflexão crítica sobre os conteúdos postados, porém a maioria dos estudantes ainda não atingiu o grau de plena autoria ao produzirem e compartilharem algo novo ou a criação inovadora de conteúdos. A pesquisa demonstrou ser possível estas atitudes quando a escola elabora projetos pedagógicos nesta perspectiva, superando as diferenças individuais visando um projeto comum.<br> / Abstract : This dissertation is based on the critical perspective that defends the non-neutraly of technologies in the cybercritical approach supported by Rudiger and it tries a supported pedagogical practice in media education to promote a critical and creative appropriation of TIC in education, such as content and as a pedagogical tool. Critical training can be guided by attitudes such as authorship and cooperation promoted by social networks and creative projects mediated by the teacher, based on the Media-Education, as a proposal for overcoming of the pedagogy of transmission. The research intends to identify factors and circumstances (which can promote) to the development of authorship and cooperation in educational activity on Facebook. This is a case study with participant observation of a Facebook appropriation experience (study group) in the preparation of high school graduate students for ENEM exams in 2015, held in a basic education public state school of Santa Catarina, located in the town of Leoberto Leal. From data collection (questionnaires and published contents), a research instrument was used whose purpose was to select and define indicators for the concepts of authorship and cooperation from the theoretical framework, and develops metrics (evidences) for content analysis the communicative exchanges between students and teachers. The results show that use social networks, conserving the logical contents and repeating textbook models, reducing the student participation just I looking, listening, coping and doing, will no form critical citizens immersed in digital culture. There were critical reflection about the posted contents, but most students have not reached the level of full authorship to produce and share something new or an innovative content creation. The research shows that is possible to create attitudes as the school prepares educational projects in this perspective, overcoming individual differences toward a common project.

Made available in DSpace on 2014-06-11T19:35:40Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-12-20Bitstream added on 2014-06-13T19:05:49Z : No. of bitstreams: 1 sanches_al_dr_guara.pdf: 891253 bytes, checksum: e63f7ccd2ae9f6655be05af4f8afb22d (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A acirrada competitividade entre as empresas de manufatura, presente no cenário atual, exige a busca por sistemas produtivos cada vez mais eficientes e que estejam inseridos num ambiente de constante aprimoramento. Visando à redução de estoques, e agilidade na produção, o conceito de produção enxuta se apresenta como um conjunto de importantes ferramentas operacionais. Desde que surgiram os conceitos associados à produção enxuta, vários estudos que tratam da utilização eficaz de Linhas de Montagem de Modelos Mistos - LMMM se concentram no sequenciamento de tais linhas. Neste trabalho, linhas de montagem múltiplas para modelos mistos, em ambiente de produção enxuta, são estruturas operacionais nas quais vários fornecedores internos abastecem várias linhas de montagem de modelos mistos simultaneamente, de modo que todas as linhas possam receber peças ou subconjuntos de todos os fornecedores. Para otimizar este sistema, a sequência de programação deve buscar o consumo constante de peças ou subconjuntos, minimizando, assim, o dimensionamento dos kanbans e estoques intermediários e, ainda, nivelar a carga de trabalho em cada posto, minimizando as paradas de linha. Baseado no clássico Problema de Monden, que determina o sequenciamento de uma única linha, este trabalho desenvolve um modelo computacional utilizando a Meta-heurística Simulated Annealing e a Simulação a Eventos Discretos para o sequenciamento do sistema de abastecimento cruzado com várias linhas. O modelo proposto busca o sequenciamento das linhas de montagem que mais aproxima o consumo real de um consumo ideal constante e atende a um padrão de eficiência predefinido para as linhas / The fierce competition between manufacturing companies, in this current scenario requires the search for production systems more efficient, and which are embedded in an environment of continuous improvement. Seeking to reduce inventories, and speed of production, the concept of lean production is presented as a range of important operational tools. Since the rise of concepts associated with lean production, several studies dealing with the effective use of assembly lines mixed models - LMMM focus on the sequencing of such lines. In this work, multiple assembly lines for mixed models, in an environment of lean production, are operating structures where several domestic suppliers supply many assembly lines mixed models simultaneously, so that all lines can get parts or subsets of all suppliers. To optimize this system, the programming sequence must seek constant consumption of parts or subassemblies, thus minimizing the scaling of kanbans, and intermediate stocks and also level the workload at each station to minimize line stoppages. Based on the classic problem Monden, which determines the sequencing of a single line, this paper develops a computational model using the Simulated Annealing metaheuristic and Discrete Event Simulation for the sequencing of the supply system with crossed several lines. The proposed model seeks the sequencing of assembly lines that most approximates the actual consumption of a consumption ideal constant and respects a predefined standard of efficiency for the lines

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Submitted by Bruna Rodrigues (bruna92rodrigues@yahoo.com.br) on 2016-09-22T11:20:41Z No. of bitstreams: 1 DissLSH.pdf: 5264839 bytes, checksum: 335e4744831b540d8bab68a8d28d6c01 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-27T20:10:31Z (GMT) No. of bitstreams: 1 DissLSH.pdf: 5264839 bytes, checksum: 335e4744831b540d8bab68a8d28d6c01 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-27T20:10:38Z (GMT) No. of bitstreams: 1 DissLSH.pdf: 5264839 bytes, checksum: 335e4744831b540d8bab68a8d28d6c01 (MD5) / Made available in DSpace on 2016-09-27T20:10:49Z (GMT). No. of bitstreams: 1 DissLSH.pdf: 5264839 bytes, checksum: 335e4744831b540d8bab68a8d28d6c01 (MD5) Previous issue date: 2014-01-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / This work shows the development, construction, validation and application of an in-line colorimeter used for real time color quantification of the melted flow during polymer processing in the extruder. The device uses a set of four colored LED’s, red (R), green (G), blue (B) and white (W), that intermittently and sequentially illuminate the melt flow with its intensity transmitted through the flow and quantified by a single photocell. At first the device was validated in bench using aqueous colored solutions and later in the extruder during processing, using known concentrations of the acid dye diluted in polymer. The device was able to quantify with precision and in real time the attenuation of the different wavelengths emitted by each LED, caused by the presence of chromophore groups in the melted flow. It was successful to use to monitor in real time the degradation of polypropylene submitted to multiple extrusions. Degradation was proven through off-line analyses of multiprocessed polypropylene via rheometry and spectroscopy absorption on UV-visible. It was also used to quantify color in the melted mixture of polypropylene/montmorillonite (PP/MMT) to obtain nanocomposites. Using hue and luminosity parameters of the color it was possible to follow oxidation of iron ions present as impurity in the clay structure, determining which clays were better suited to these nanocomposite production. / Este trabalho mostra o desenvolvimento, construção, validação e aplicação de um Colorímetro in-line para a quantificação em tempo real da cor do fluxo fundido durante o processamento do polímero na extrusora. Ele é constituído por um conjunto de quatro LEDs (Light Emitting Diode) nas cores vermelho (R), verde (G), azul (B) e branco (W) que iluminam de forma intermitente e sequencial o fluxo fundido sendo a intensidade da luz transmitida através do fundido quantificada por uma única fotocélula. Inicialmente o dispositivo foi validado em bancada, com o uso de fluxo de soluções aquosas coloridas e a seguir diretamente no processo de extrusão, com o uso de formulações de polímero tingido com corante ácido em concentrações conhecidas. O dispositivo mostrou-se capaz de quantificar com precisão e em tempo real a atenuação dos diferentes comprimentos de onda da luz emitida pelos diferentes LEDs, causada pela presença de grupos cromóforos presentes no fluxo fundido. Ele foi utilizado com sucesso no monitoramento em tempo real da degradação do polipropileno submetido a múltiplas extrusões. Esta foi comprovada através de medidas off-line das características reológicas e de absorção no espectro UV-visível do polipropileno multiprocessado. Também foi usado para a quantificação da cor formada durante a mistura no estado fundido para a formação de nanocompósitos de polipropileno/montmorilonita (PP/MMT). Através da análise dos parâmetros de tonalidade e luminosidade da cor foi possível acompanhar a oxidação dos íons de ferro presentes como impureza na estrutura da argila e assim determinar as melhores argilas na produção destes nanocompósitos.