332 resultados para Confiabilidade


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In an ever more competitive environment, power distribution companies must satisfy two conflicting objectives: minimizing investment costs and the satisfaction of reliability targets. The network reconfiguration of a distribution system is a technique that well adapts to this new deregulated environment for it allows improvement of reliability indices only opening and closing switches, without the onus involved in acquiring new equipment. Due to combinatorial explosion problem characteristic, in the solution are employed metaheuristics methods, which converge to optimal or quasi-optimal solutions, but with a high computational effort. As the main objective of this work is to find the best configuration(s) of the distribution system with the best levels of reliability, the objective function used in the metaheuristics is to minimize the LOLC - Loss Of Load Cost, which is associated with both, number and duration of electric power interruptions. Several metaheuristics techniques are tested, and the tabu search has proven to be most appropriate to solve the proposed problem. To characterize computationally the problem of the switches reconfiguring was developed a vector model (with integers) of the representation of the switches, where each normally open switch is associated with a group of normally closed switches. In this model simplifications have been introduced to reduce computational time and restrictions were made to exclude solutions that do not supply energy to any load point of the system. To check violation of the voltage and loading criteria a study of power flow for the ten best solutions is performed. Also for the ten best solutions a reliability evaluation using Monte Carlo sequential simulation is performed, where it is possible to obtain the probability distributions of the indices and thus calculate the risk of paying penalty due to not meeting the goals. Finally, the methodology is applied in a real Brazilian distribution network, and the results are discussed.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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In chemical industry, petrochemical and oil refinery may be found situations that working pressures and very high temperatures, and alloys that comprise such equipment must have specific characteristics such. As a way to ensure that the materials are as designed, companies have some specific techniques, and one of them is X-ray fluorescence spectrometry, which allows its application in devices small and lightweight, which ensures its portability in field use. This technique however, has some shortcomings such as the impossibility of detecting carbon and other elements of low atomic number which can generate false identifications of elements that are not in the league or non-detection of existing elements. Therefore, this study investigated the reliability of this method using the apparatus Niton XL3t 800 and may conclude that their results are reliable and can be used to assist in ensuring the operational integrity of the production units of these companies

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The growing demand for quality at competitive prices and fast production process put to the test function in the industrial Maintenance. The need for equipment with high availability to fit this fierce competitiveness makes maintenance becomes essentially reliable. Despite this current context, many companies still have an old view of maintenance, focused only on corrective services, and proposals for change are often neglected due to the sense of urgency day to day. Thus, this study aims to demonstrate through theoretical applicability of simple tool, but of great value in increasing reliability within the maintenance sector of an industry, applying the concepts of Reliability Centered Maintenance – RCM and Analysis tool Failure Modes and Effects – FMEA in equipment of a chemical company directly involved in the manufacturing process of the brake fluid, which this product is used in vehicles around the country. That way, you can identify the types, occurrence and criticality of each failure and evaluate assertively decision making for each device, avoiding unnecessary downtime and potential failures of the same

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The constant search for improvements and the survival of organizations makes the strategic guidelines are deployed and executed at the operational levels. This work is the approach to critical analysis of the equipment of a chemical industry through a case study based on the classification of each equipment manufactures through qualitative and quantitative analysis on the pillars of maintenance costs, loss of production, MTBF, contribution margin, Health Safety and Environment (SHE). From this study and future data collection, along with the flow diagram show the main equipment that should be special attention. To this can be prepared an action plan with deadlines and responsible. With the results one can measure the maintenance costs, loss of production and technical availability of the plant, with future gains

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The objective of this work is to perform a study applying the methodology of Reliability Centered Maintenance - MCC to a group of cranes belonging to Amsted -Maxion in Cruzeiro - SP. The work consists of a presentation of maintenance, the reasons why more and more people worry about maintenance, making a presentation on the types of maintenance, its peculiar characteristics and then do a study where you identified the functionality required by the equipment under study, identified failure modes and their probable causes, and then detail the effects and consequences of these failures. With that evaluate the criticality of these failures and identify the most significant consequences that affect safety, availability or cost of equipment operation and allow a selection of the most appropriate tasks for the identified failure modes. We will also present best crane equipment, its main components, verify that there was or not improvement in the machine after the application of MCC and make a current analysis of maintenance in Amsted -Maxion

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The objective of this study was to estimate the reliability of the alcohol use disorders identification test (AUDIT) applied to adolescents. Evaluations were performed with 141 students of ages ranging from 14 to 17 years (14.93±0.62). The internal consistency of the instrument was estimated by Cronbach’s alpha coefficient and its reproducibility by weighted Kappa statistics by score and by a reliability interval of 95%. The AUDIT presented excellent internal consistency (α=0.80, rinter-item=0.29). Most questions present reproducibility ranked as “good”. It is concluded that the AUDIT is a reliable instrument to survey information about alcohol use in adolescents.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The annual vaccination campaign against rabies is the most effective prevention procedure for this disease in dogs and cats and hence for human protection also. However, in 2010 and 2011, this activity was interrupted in Brazil due to the occurrence of adverse events associated with vaccination. Even though cases of canine rabies have been decreasing in the last two decades, vigilance must be strengthened in order to maintain pet owners trust in the vaccines provided in public services. This study aimed to determine pet owners participation in the annual vaccination campaign carried out in Botucatu. During March and April 2012, the period before the 42nd campaign, 312 pet owners, dogs and cats, were interviewed. The homes were randomly drawn in blocks from different sectors of the city; all houses on the same block over the 120 km² of urban area participated in the sampling process. Statistical analysis was performed descriptively. The results showed that the owners main motivation to vaccinate their pets during the campaigns is rabies prevention (36%), followed by the proximity of the vaccination station to the house (20.7%), zero cost (10.9%), and the combination of all three factors (16.1%). When asked if they would take their animals back to be vaccinated in another campaign, 60.1% answered yes, 13.5% would go to a private clinic, 2.2% would not take because they do not trust the vaccine and 1.6% had not decided yet. We conclude that the respondents have realized how dangerous Rabies is, because even after the break period, they still utilized the vaccination campaign demonstrating confidence in its effectiveness, while knowing the campaign goals facilitates understanding and participation.

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In this work, the author looks forward to develop a new method capable of incorporate the concepts of the Reliability Theory and Ruin Probability in Deep Foundations, in order to do a better quantification of the uncertainties, which is intrinsic in all geotechnical projects, meanly because we don't know all the properties of the materials that we work with. Using the methodologies of Decourt Quaresma and David Cabral, resistance surfaces have been developed utilizing the data achieved from the Standard Penetration Tests performed in the field of study, in conjecture with the loads defined in the executive project of the piles. The construction of resistance surfaces shows to be a very useful tool for decision making, no matter in which phase it is current on, projecting or execution. The surfaces were developed by Kriging (using the software Surfer® 12), making it easier to visualize the geotechnical profile of the field of study. Comparing the results, the conclusion was that a high safety factor doesn't mean higher security. It is fundamental to consider the loads and resistance of the piles in the whole field, carefully choosing the project methodology responsible to define the diameter and length of the piles

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A maioria das instalações de abastecimento de água utiliza bombas hidráulicas do tipo turbobombas, requerendo que o interior de sua carcaça e da tubulação de sucção esteja preenchido com água (escorvados) para que a sucção da água possa ser efetivada. O escorvamento das bombas pode ser efetuado instalando-as abaixo do reservatório de captação (bomba afogada). Quando a bomba está acima do reservatório e o escorvamento é manual, é necessário usar válvulas-de-pé, que são suscetíveis ao mau funcionamento, limitando a confiabilidade do sistema, principalmente em caso de automação. Como alternativa à válvula-de-pé, neste trabalho, foram estudados dois tanques escorva, testados no Laboratório de Hidráulica e Irrigação da FCAV/UNESP - Jaboticabal, avaliando-se situações de altura manométrica de sucção de bomba centrífuga e relações entre volume útil do tanque e volume do tubo de sucção, tendo-se concluído: a) o volume do tanque de escorva é função do volume do tubo de sucção da instalação de bombeamento e da altura manométrica de sucção; b) o volume do tanque de escorva pode ser calculado seguindo-se a Lei de Boyle, com percentagem de acréscimo que, neste estudo, foi de 10% para um modelo de tanque e de 30% para o segundo modelo.

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O objetivo deste trabalho foi confrontar as sequências parciais do gene 16S rRNA de estirpes padrão de rizóbios com as de estirpes recomendadas para a produção de inoculantes no Brasil, com vistas à verificação da confiabilidade do sequenciamento parcial desse gene para a identificação rápida de estirpes. Foram realizados sequenciamentos através de reação em cadeia da polimerase (PCR) com iniciadores relativos à região codificadora do gene 16S rRNA entre as bactérias estudadas. Os resultados foram analisados pela consulta de similaridade de nucleotídeos aos do Basic Local Alignment Search Tool (Blastn) e por meio da interpretação de árvores filogenéticas geradas usando ferramentas de bioinformática. A classificação taxonômica das estirpes Semia recomendadas para inoculação de leguminosas com base em propriedades morfológicas e especificidade hospedeira não foi confirmada em todas as estirpes. A maioria das estirpes estudadas, consultadas no Blastn, é consistente com a classificação proposta pela construção de árvores filogenéticas das sequências destas estirpes, com base na similaridade pelo sequenciamento parcial do gene considerado.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Os objetivos do estudo foram avaliar o alinhamento, no plano sagital, da coluna de indivíduos com alterações na medida da gibosidade, comparando com um grupo sem alterações; testar a confiabilidade do instrumento utilizado e verificar se existem correlações entre as medidas da gibosidade e os valores das curvaturas vertebrais. Foram avaliados 40 jovens, divididos em grupo controle - ausência ou presença de gibosidades inferiores a 0,5 cm na curvatura torácica e 0,7 cm na lombar (n=20) e, grupo experimental - gibosidades superiores às descritas (n=20). A gibosidade e as curvaturas no plano sagital foram mensuradas com um instrumento adaptado a um nível d'água e o teste de Adams. As coletas foram realizadas em duas datas distintas, nos dois grupos. Após aplicação do teste Mann-Whitney não foi encontrada diferença entre as ocasiões de coletas e, emparelhando-se os grupos, foi encontrada diferença apenas na medida cervical. Na verificação de existência de relação entre as medidas coletadas, foi encontrada correlação linear (Spearmann) no grupo controle - curvatura torácica e gibosidade torácica; em ambos os grupos - curvaturas torácica e lombar; e no grupo experimental - gibosidade torácica e as curvaturas lombar e sacral e, curvatura sacral e curvaturas torácica e lombar. Pôde-se concluir que a medida da gibosidade tem relações com as curvaturas no plano sagital. Por ser um método confiável, simples e acessível, pode ser reproduzido sem altos custos financeiros e sem causar prejuízo à saúde do paciente.