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Students' perceptions of service quality at the Durban University of TechnologyArpin, Justin January 2007 (has links)
Thesis (M.B.A.)-Business Studies Unit, Durban University of Technology, 2007. xiii, 112 leaves. / Interest in the quality of university education has grown considerably over the last decade. Higher education institutions are increasingly placing greater emphasis on meeting students’ expectations and needs. As universities become more student orientated, student perceptions of higher educational facilities and services are becoming more important. It is apparent that there is a need to measure students’ perceptions of service quality at the Durban University of Technology.
To investigate students’ perceptions of service quality, a study was conducted which was guided by four objectives. These objectives were: firstly, to identify students’ expectations in terms of higher educational services provided; secondly, to ascertain the perceptions of students towards the service the Durban University of Technology provides; thirdly, to measure the gaps between the expectations and perceptions, using the SERVQUAL score, and fourthly, to calculate and measure the score of the five SERVQUAL dimensions. / M
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Výpočty plánů pro statistické přejímky měřením / Calculation of Acceptance Sampling Plans for Inspection by VariablesKaspříková, Nikola January 2006 (has links)
Analysis of several acceptance sampling procedures is performed and improvement of the procedures is sug- gested in this thesis. The issue of an efficient calculation of exact (P1, P2) single sampling plans for sampling by variables and exact LTPD and AOQL single sampling plans for sampling by variables when the rejected lots are inspected is addressed. The calculation of the plans is done using exact formula for operating characteristic of acceptance sampling plan and the new plans have better characteristics compared to the plans computed in a usual way using just approximately valid formula for operating characteristic. The tables of plans calculated according to procedures suggested in this thesis are provided for a couple of input parameters combinations. Tools designed for working with acceptance sampling plans, tools for analysis and calculation of acceptance sampling plans is one of the outputs of this thesis. R language and environment for statistical computations was chosen for implementation. The tools are satisfactorily efficient and may be easily used even for acceptance sampling plans tables computation. Newly defined functions in R are supplied including their source code and basic documentation so that acceptance sampling plans can be computed as demanded in case that the particular input parameters set is out of the scope covered in the tables of plans provided here.
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Effects of concrete quality and cover depth on carbonation-induced reinforcement corrosion and initiation of concrete cover cracking in reinforced concrete structuresIkotum, Jacob Olumuyiwa January 2017 (has links)
A thesis submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy, Johannesburg, 2017 / Many reinforced concrete (RC) structures in inland environment deteriorate early due to carbonation-induced corrosion of their reinforcement. In some cases, the deterioration is visible within a few years of construction in the form of cover concrete cracking. This is widely accepted as one of the limit state indicators in defining the end of functional service life for existing RC structures undergoing corrosion. Many of the currently available service life prediction models are incapable of providing realistic service life estimates of RC structures beyond the corrosion initiation stage. Therefore, the need to incorporate the corrosion initiation and propagation stages in a comprehensive durability prediction approach has been receiving much research attention.
In this research, empirical models were developed for predicting carbonation rate and the amount of steel radius loss required to initiate a first visible crack in concretes exposed to Johannesburg environment. The experimental data for the models were obtained from investigations of carbonation-induced reinforcement corrosion, which were explored in three phases; (i) concrete early-age durability and strength characteristics (ii) carbonation rate of different concrete mixes exposed to the natural inland environment (iii) amount of steel radius loss required to initiate the first visible crack on the pre-carbonated cover concretes exposed to an unsheltered environment. The experimental variables for the earlyage durability and strength tests were; water/binder ratio (w/b) and binder type; w/b, binder type, initial moist curing duration and exposure conditions are the experimental variables for the carbonation rate test. Cover depth, reinforcement diameter, binder type and w/b variables were considered for the corrosion cracking test.
The results showed that an improvement in concrete quality (binder type, w/b ratio and extending the initial moist curing duration) and increment in cover thickness improved the durability of the RC structures exposed to the natural inland environment. Based on the trends in the observed experimental results, models to predict carbonation rate and the amount of steel radius loss required to initiate cover cracking in concrete were developed. The proposed models’ predictions are more closer to the measured values and compared well with the predictions of some previous models which indicate their respective predictive applications. They provide a general basis for durability analysis of RC structures in inland environment and can serve as basis for condition assessment of existing structures in the inland environment. Engineers can appreciate the consequences of design options on the service life of RC structures, while owners of RC structures can have information about how long their RC structures may last before any repair is envisaged / XL2018
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Accelerated curing of concrete with high volume pozzolans - resistivity, diffusivity and compressive strengthUnknown Date (has links)
This investigation presents results of the temperature effect on durability properties (resistivity and diffusivity) and compressive strength of concrete with pozzolans, and the effect of pozzolanic admixtures on microstructure and chemical compositions of concrete pore solution. ... Temperature dependence of electrical resistivity and chloride diffusivity was studied by dynamic temperature tests. Accelerated curing regimes involving curing concrete specimens in 35À C lime water with different durations were tested. Compressive strength test, resisivity measurement and rapid chloride migration (RCM) tests were performed. A leaching method was used to measure pH and conductivity of concrete pore solution. ... The accelerated curing regimes were found to increase the compressive strength and resistance to chloride ion penetration at short-term and long-term. With the developed correlation between resistivity and migration coefficients, it is possible to employ the resistivity measurement as an alternative or replacement of the RCM test to evaluate resistance of chloride ion penetration of concrete. Pozzolanic admixtures were found to decrease both pH and conductivity of concrete pore solution as the replacement ratio increased. Moreover, the migration coefficients were found to be greatly correlated to the microstructure properties of concrete, such as porosity, formation factor and tortuosity. / by Yanbo Liu. / Thesis (Ph.D.)--Florida Atlantic University, 2012. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.
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Contribuição ao controle tecnológico de concretos estruturais de cimento Portland em ambientes marítimos. / Contribution to field quality control of Portland cement structural concretes in maritime environments.Cavalcanti Filho, Antonio Nereu 18 June 2010 (has links)
A durabilidade dos edifícios em concreto armado só pode ser alcançada se for atendido um conjunto de requisitos e critérios nas etapas de projeto, execução e manutenção, nas quais os materiais envolvidos precisam ser adequadamente especificados, produzidos e empregados, de acordo com as respectivas rotinas dessas etapas. Assim, o requisito genérico de proteção das armaduras de aço carbono, para a durabilidade de estruturas, é contemplado por vários critérios, desde a etapa de projeto. Esta dissertação trata dos critérios pertinentes à qualidade do concreto e visou contribuir para a evolução de procedimentos para o controle tecnológico de concretos estruturais de cimento Portland, em atmosferas marítimas e urbanas, em clima tropical, com vistas à proteção de armaduras de aço carbono. O programa experimental estudou três lotes diferentes de concretos estruturais, semelhantes quanto a especificações básicas de abatimento: 10 ± 2 cm, de fck 30 MPa e para ambiente classe III da NBR 6118 (2003). O objetivo foi caracterizar e analisar a influência de propriedades físicas do estado fresco sobre o estado endurecido de concretos, dentro da faixa de consistência citada, com ênfase nas propriedades relacionadas ao teor de ar das misturas e suas respectivas resistências à carbonatação e ao ingresso de íons cloreto. A amostragem, os ensaios no estado fresco e a moldagem dos corpos-de-prova foram realizados durante três concretagens conduzidas em duas obras de edifícios de múltiplos andares, na cidade de João Pessoa/PB. As composições e a produção dos lotes ficaram a cargo da central dosadora e fornecedora do concreto em cada obra. O lote inicial serviu para o treinamento da equipe, em campo e laboratório, com amostragem de seis caminhões. Os outros dois lotes, identificados como 1 e 2, foram caracterizados em condições bastante semelhantes, sempre pela mesma equipe, e representados pela amostragem de cinco e seis caminhões, respectivamente. As propriedades medidas no estado fresco foram: abatimento do tronco de cone pela ABNT NBR NM 67 (1998); teor de ar por método pressométrico da ABNT NBR 47 (2002); massa específica pela ABNT NBR 9833 (2008); relação água/materiais secos por analogia à ABNT NBR 9605 (1992); e compactabilidade dos concretos adensado e não adensado, por adaptação da BS EN 12350-4 (2008). Para o estudo das propriedades no estado endurecido, os corpos-de-prova eram cilíndricos, com 10 cm de diâmetro e 20 cm de altura, e foram maturados por dois métodos adaptados do Tipo A da ASTM C 684 (1999). Certas propriedades foram ainda caracterizadas para condições normais de cura da ABNT NBR 5738 (2003). As propriedades estudadas no estado endurecido foram: resistência à compressão pela ABNT NBR 5739 (2007); resistência à tração por compressão diametral pela ABNT NBR 7222 (1994); absorção de água por capilaridade pela ABNT NBR 9779 (1995); absorção de água total e índice de vazios pela ABNT NBR 9778 (2005); resistência à carbonatação em câmara com CO2 (5%; UR 65 + 10 %; 23 + 3 °C); e resistência à penetração de cloretos e CO2, por três ciclos de um dia de molhagem e 27 dias de secagem, entre sete e 91 dias. De modo complementar, foram moldados corpos-de-prova específicos de aço e concreto, para medidas de potencial de circuito aberto, com vistas à continuidade de pesquisas sobre envelhecimento acelerado. A maioria das propriedades foram medidas por duas repetições, constando os resultados individuais em apêndices. A análise inicial dos resultados dos três lotes foi descritiva e resumiu em tabelas o valor médio, desvio padrão, valor máximo, valor mínimo, a amplitude e o coeficiente de variação de cada lote. As propriedades de cada lote também foram comparadas por análise de variância e, ao final, foram correlacionadas de modo conjunto, independentemente do lote de origem. Nesse caso, foram destacadas as melhores correlações entre propriedades, independentemente dos materiais constituintes de cada concreto. Entre as propriedades do estado fresco, destacaram-se as seguintes: a) o abatimento do tronco de cone apresentou correlação forte e inversa (r² = -0,802, para lotes 1 e 2) com resistência à compressão após um dia de cura acelerada em temperatura moderada, em método similar ao Tipo A da ASTM C 684 (1999); b) o teor de ar pelo método pressométrico apresentou correlações de razoáveis a fortes com a resistência à compressão a 28 dias (r² = -0,698, para lotes 1 e 2), com a resistência à tração por compressão diametral por cura acelerada a sete dias (r² = -0,818, para lotes 1 e 2), com a profundidade de carbonatação em câmara de CO2 (r² = 0,699, para lotes 1 e 2) e com a profundidade de penetração de cloretos por três ciclos de imersão e secagem (r² = 0,625, para lotes 1 e 2); c) as medidas de compactabilidade do concreto adensado, ainda que realizadas em condições de campo, apresentaram várias correlações moderadas com outras propriedades do estado fresco e endurecido. No estado endurecido, destacaram-se as seguintes correlações: a) r² da ordem de -0,75 para a resistência à compressão a um dia dos concretos dos lotes 1 e 2, com cura acelerada de 0/24 horas em temperatura moderada, e a profundidade de carbonatação em câmara de CO2 (5%) e a de penetração de cloretos por três ciclos de imersão e secagem, ambas analisadas a 91 dias, tendo os corpos-de-prova recebido cura inicial acelerada de 24/48 h, em temperatura moderada, seguida de imersão normal por até sete dias; b) r² de -0,682 entre a resistência à tração por compressão diametral, com cura acelerada de 24/48h em temperatura moderada seguida de cura normal por até sete dias, e a profundidade de ingresso de íons cloreto, para os três lotes submetidos aos ciclos citados; c) valores de r² entre 0,521 e - 0,561 para as correlações entre a absorção de água por capilaridade, em corpos-de-prova submetidos à cura inicial acelerada em temperatura moderada por 24/48 h e em temperatura normal por até sete dias, e a resistência à carbonatação para os lotes submetidos aos ciclos citados. Assim, esta pesquisa conclui e propõe que, além do teor de ar no estado fresco, as resistências à compressão e à tração por compressão diametral entre um e sete dias, por cura acelerada do Tipo A da ASTM C 684 (1999) ou por duração adaptada da mesma, sejam propriedades que passem a ser avaliadas em concretos, com vistas a melhorar e controlar a sua resistência a agentes agressivos. Nesta pesquisa, a microestrutura nas primeiras idades do concreto mostrou ser mais determinante da rede de conexão de poros e do transporte de agentes agressivos do que a microestrutura em idades mais avançadas de hidratação; e trabalhos futuros devem confirmar esta interpretação. Espera-se que estes resultados possam estimular novas práticas de qualificação de concretos em estudos de dosagem ou no ato do recebimento de concretos pré-misturados, especialmente em ambientes mais agressivos às armaduras, com vistas à futura evolução de procedimentos da ABNT NBR 12655 (2006). / Durability of reinforced concrete buildings can only be achieved if a set of requirements and criteria is met in the design, execution and maintenance phases, in which the materials must be properly specified, manufactured and employed, according to the respective procedures of these phases. Therefore, the general requirement of protection of carbon steel reinforcements, for structural durability, is contemplated by several criteria as early as the design phase. This thesis addresses the relevant criteria concerning concrete quality and its objective was to contribute to the evolution of technological control procedures for Portland cement structural concretes, in urban and maritime atmospheres in tropical climate, aiming at the protection of carbon steel reinforcements. The experimental program studied three different batches of structural concrete that were similar in terms of slump test basic specifications: 10 ± 2 cm, fck = 30 MPa and class III of ABNT NBR 6118 (2003) environmental classification. The goal was to characterize and analyze the influence of physical properties of fresh concrete on hardened concrete, within the previously mentioned consistency range, with emphasis on those properties related to air content of the mixtures and their respective carbonation and chloride ion penetration resistances. Sampling, fresh concrete tests and specimen molding were conducted during three cast-in-place concretes in two construction sites of multi-storey buildings in the city of João Pessoa, state of Paraíba, in Brazil. The batch plant supplying the concrete for each construction site was responsible for batch composition and production. The initial batch was used to train the team, in the field and laboratory, with a sample of six trucks. The other two batches, identified as 1 and 2, were characterized under very similar conditions, always by the same team, and the samples consisted of five and six trucks, respectively. The properties measured in fresh concrete were: slump test according to Brazilian norm ABNT NBR NM 67 (1998); air content by the pressure method of ABNT NBR 47 (2002); bulk density according to ABNT NBR 9833 (2008); water/dry material ratio by analogy with ABNT NBR 9605 (1992); and compactability of compacted and non-compacted concretes, by adaptation of BS EN 12350-4 (2008). In order to study the properties of hardened concrete, the specimens were cylindrical, measuring 10 cm in diameter and 20 cm in height, and were matured by using two methods adapted from Type A of ASTM C 684 (1999). Some properties were also characterized for normal curing conditions according to ABNT NBR 5738 (2003). The properties studied in hardened concrete were: compressive strength according to ABNT NBR 5739 (2007); splitting tensile strength as per ABNT NBR 7222 (1994); capillary water absorption according to ABNT NBR 9779 (1995); water absorption by immersion and void ratio following ABNT NBR 9778 (2005); carbonation resistance in CO2 chamber (5%; 65 + 10 % RH; 23 + 3 °C); and chloride and CO2 penetration resistance, using three one-day wet and 27-day dry cycles, between seven and 91 days. As a complement, specific steel and concrete specimens were molded to measure open circuit potential, aiming at the continuity of researches on accelerated ageing. Most properties were measured twice and the individual results are presented in appendices. Preliminary analysis of results from the three batches was descriptive and summarized in tables the mean value, standard deviation, maximum value, minimum value, amplitude and coefficient of variation for each batch. The properties of each batch were also compared using analysis of variance and, at the end, were correlated as a whole, regardless of the batch of origin. In this case, the best correlations among properties were highlighted, regardless of the materials used in each concrete. Among the properties of fresh concrete, the following are noteworthy: a) the slump test presented strong and inverse correlation (r² = -0.802, for batches 1 and 2) with compressive strength after one day of accelerated curing at moderate temperature, using a method similar to Type A of ASTM C 684 (1999); b) air content in the pressure method presented reasonable to strong correlations with compressive strength at 28 days (r² = -0.698, for batches 1 and 2), with splitting tensile strength with accelerated curing at seven days (r² = - 0.818, for batches 1 and 2), with carbonation depth in CO2 chamber (r² = 0.699, for batches 1 and 2) and with chloride penetration depth after three immersion-drying cycles (r² = 0.625, for batches 1 and 2); c) compactability measurements of compacted concrete, despite being taken in field conditions, presented several moderate correlations with other properties of fresh and hardened concrete. In hardened concrete, the following correlations should be highlighted: a) r² was -0.75 for compressive strength at one day of the concretes from batches 1 and 2, with 0/24- hour accelerated curing at moderate temperature, and carbonation depth in CO2 chamber (5%) and chloride penetration depth after three immersion-drying cycles, both analyzed at 91 days, after the specimens underwent 24/48-hour initial accelerated curing at moderate temperature, followed by normal immersion for up to seven days; b) r² was -0.682 between splitting tensile strength, with 24/48-hour accelerated curing at moderate temperature followed by normal curing for up to seven days, and chloride ion penetration depth, for the three batches submitted to the aforementioned cycles; c) r² values between 0.521 and - 0.561 for the correlations between capillary water absorption, in specimens submitted to initial accelerated curing at moderate temperature for 24/48h and at normal temperature for up to seven days, and carbonation resistance for the batches submitted to the aforementioned cycles. Therefore, this research concludes and proposes that, besides air content in fresh concrete, compressive strength and splitting tensile strength between one and seven days, using accelerated curing of Type A of ASTM C 684 (1999) or for a duration adapted from that norm, are properties that should be evaluated in concrete, with the purpose of improving and controlling resistance to aggressive agents. In this research, the microstructure of the early ages of concrete proved to be more determinant of the pore structure connection and of the transport of aggressive agents than the microstructure at later ages of hydration; and future studies should confirm this interpretation. It is expected that these results will encourage new practices for the qualification of concrete in mixture proportion studies or when ready mixed concrete is received at construction sites, especially in environments that are more aggressive to reinforcements, with a view to developing future procedures of ABNT NBR 12655 (2006).
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A adoção da metodologia seis sigma por pequenas e médias empresas brasileiras do setor de autopeças. / Sem título em inglêsDuarte Junior, Nasario de Sousa Filipe 04 May 2007 (has links)
A metodologia Seis Sigma vem sendo disseminada entre as grandes empresas, principalmente multinacionais, porém o mesmo não vem ocorrendo com as micro, pequenas e médias empresas (MPMEs), em especial as nacionais. Dentre este universo de MPMEs brasileiras, as autopeças são um caso de particular interesse, pois as mesmas enfrentam sérios problemas de competitividade e raras buscam o Seis Sigma como solução, mesmo tendo a maioria já investido na implantação de programas da qualidade utilizando outras metodologias com elementos comuns ao Seis Sigma, como Sistemas de Gestão da Qualidade, TQM (Total Quality Management) e Manufatura Enxuta. Esta pesquisa, um estudo exploratório realizado por meio de um survey, objetivou então conhecer os fatores que influenciam a decisão de adoção ou não do Seis Sigma por MPMEs nacionais de autopeças, e os resultados levaram a concluir que estes seriam: a conscientização da Direção, a competência preexistente para condução de projetos, o volume de recursos disponíveis e a preexistência de uma cultura da qualidade. Com base nestas conclusões foram apresentadas sugestões que visam facilitar a adoção da metodologia por este importante conjunto de empresas nacionais, esperando com isso contribuir em sua busca por competitividade. / The Six Sigma methodology is being spread among big companies, mainly by international companies, however the same is not happening within the small and midsize enterprises (SMEs), in particular, the national ones. In this universe of SMEs, the national auto parts industries have an interesting case, because they face serious competitiveness problems and rarely use Six Sigma as a solution, despite that majority have already invested in other quality programs implementation using methodologies which have elements in common with the Six Sigma, like Quality Management Systems, TQM (Total Quality Management) and Lean Manufacturing. This research, a exploratory survey study, had the objective of knowing the factors that have had influence over the SMEs Brazilian auto parts decision of whether to adopt the Six Sigma or not, and the results led us to conclude they are: the Direction awareness, the competence pre-existent to manage projects, the resource availability and the pre-existence of a quality culture. Based on those conclusions, suggestions were presented in order to make this methodology adoption easier by these important national companies set, in the expectation of contributing in their search for competitiveness.
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Desenvolvimento de candidato a material de referência certificado para Uísque: um material eficaz para a garantia da qualidade e manutenção da ISO/IEC 17025 em Laboratórios de Ensaio / Development of candidate certified reference material for Whiskey: an effective material for quality assurance and maintenance of ISO / IEC 17025 in Testing LaboratoriesMarcki, Danieli Cristina 29 June 2017 (has links)
Atualmente, a produção de Material de Referência Certificado (MRC) tem apresentado destaque devido a sua importância na aplicação durante a validação de métodos, estimativa de incerteza e controles de rotina, atendendo uma grande demanda de laboratórios que aplicam sistemas de gestão da qualidade (como por exemplo, baseados na ISO/IEC 17025) e necessitam desenvolver estas atividades em busca da rastreabilidade metrológica. Dentre estes diferentes laboratórios, podemos destacar os laboratórios de bebidas que analisam, por exemplo, contaminantes em uísque visando um monitoramento adequado deste produto de grande consumo interno, seja de produtos importados e/ou produção nacional. Desta maneira este projeto visa o desenvolvimento de candidato a material de referência certificado (MRC) para Uísque, considerando a importância em desenvolver métodos para a produção de material de referência, sendo o uísque um excelente candidato devido à importância em monitorar adequadamente este produto que tem apresentado um crescimento exponencial de consumo nos últimos anos. / Currently, the production of CRM has been highlighted due to its importance in method validation, uncertainty measurement and routine controls, necessary for laboratories that apply quality management systems (e.g. based on ISO/IEC 17025) and need to develop these activities to achieve an adequate metrological traceability. Among these different laboratories, we can highlight the beverage laboratory that analyses, for example, contaminants in whiskey to ensure an appropriate monitoring of this product that has great domestic consumption. This project aims the development of a candidate certified reference material (CRM) for whiskey, considering the importance of developing methods for the production of reference material, being the whiskey an excellent candidate because of its importance to properly monitor this product that has shown an exponential growth of consumption in recent years.
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KAIZEN - implementação na indústria de autopeças: resultados na redução das perdas na área produtiva. / KAIZEN - implementation in the auto parts industry: loss reduction results in the productive area.Paniago, Argélio Lima 13 October 2008 (has links)
A metodologia KAIZEN é divulgada pelo mundo todo e no Brasil há muitas empresas fazendo uso dela para melhorarem seus resultados. Neste trabalho o histórico e conceitos do KAIZEN são apresentados e são as bases para o levantamento amostral realizado. Este tipo de pesquisa foi utilizado para, no ambiente da indústria de autopeças no Brasil que aplicam a metodologia KAIZEN, se conhecer como os fundamentos desta metodologia estão sendo utilizados, quais os reais resultados alcançados e quais ações são encontradas que, através do KAIZEN, encaminham a estes resultados. Foi desenvolvido um questionário como instrumento de pesquisa e este foi distribuído às empresas de interesse a este trabalho. Cada questão colocada tem seus resultados apresentados em forma de distribuição de respostas para cada opção e a discussão final utiliza estas distribuições de respostas para suas fundamentações e a conclusão do trabalho. / KAIZEN Methodology is known all over the world and in Brazil it has many companies making use of it to improve their results. In this work, the description and concepts of the KAIZEN are presented and are the bases for the survey done. This type of research was developed in the environment of the auto parts industry that applies KAIZEN methodology in Brazil to know how this methodology is being used, which the real results reached and which actions are found that, through the KAIZEN, direct to these results. A questionnaire was designed as research instrument and distributed to the companies of interest to this work. Each question has its results presented in form of distribution for each option and the final discussion uses these distributions as bases to the conclusions of the work.
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Critérios de aceitação e controle da qualidade da execução de camadas de fundação de pavimentos novos através de métodos deflectométricos. / Criteria for acceptance and quality control to execution of new pavements foundation layers through nondestructive deflection tests.Ferri, Santi 14 December 2012 (has links)
As obras de infraestrutura rodoviária representam investimentos públicos que influenciam de maneira determinante no desenvolvimento social e econômico de uma região. Pavimentos mal construídos, com controle de qualidade inadequado ou que não atendam às exigências de projeto em termos de características e espessuras dos materiais selecionados representam prejuízos sociais e econômicos na medida em que a deterioração precoce do pavimento implica em aumentos crescentes nos custos diretos e indiretos relacionados à conservação e operação rodoviária. Desta maneira, torna-se imprescindível que sejam adotadas medidas de garantia da qualidade da construção de modo que o investimento apresente melhores condições de atingir o retorno esperado, tal como planejado. Neste contexto, o presente trabalho tem por objetivo realizar revisão bibliográfica e propor ferramentas auxiliares de análise voltados ao controle deflectométrico do sistema de fundação dos pavimentos. Os estudos realizados baseiam-se em critérios estatísticos de análise e em critérios de ruptura adotados nos métodos de dimensionamento em uso corrente no Brasil e no exterior. Simulações e estudos de casos são utilizados na validação e apresentação dos modelos propostos. / The infrastructure road projects represent investments, often public, that influence in a decisive way on social and economic development of a region. Poorly constructed pavements with inadequate quality control or that do not meet design requirements in terms of selected materials characteristics and thickness represent social and economic losses since the early deterioration of the pavement results in incremental increases in direct and indirect costs related the road maintenance and operation. Thus, it is essential that actions be taken to guarantee the construction quality so that investments are more likely to achieve the expected return as planned. In this context, this research aims to conduct a literature review and propose auxiliary analysis tools related with nondestructive deflection tests in the pavements foundation systems. The studies will be based in statistical analysis criteria and failure criteria adopted in design methods currently in use in Brazil and abroad. Simulations and study cases are used in the validation and presentation of the proposed models.
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Implantação de um programa de controle de qualidade em equipamentos de raios x por meio de medidores não invasivos / Establishment of an X radiation equipment quality control programme using non invasive metersLucena, Rodrigo Ferreira de 14 September 2010 (has links)
O objetivo desse trabalho foi estudar o comportamento do principal equipamento de raios X utilizado nos procedimentos do laboratório de calibração do IPEN, LCI, operado nos intervalos de tensão de 25 a 150 kV utilizando os medidores de tensão não invasivos DiavoltTM da PTW e do sistema de espectrometria ORTEC, modelo NOMAD-PLUS 92X para o estabelecimento de um programa de controle de qualidade. O medidor Diavolt foi utilizado para as medições de kerma no ar, tensão de pico e tensão de pico prático. As medições foram feitas variando parâmetros como, corrente elétrica, Qualidade de Radiação X para Radiodiag-nóstico, angulação do medidor e sua distância em relação ao ponto focal do aparelho de raios X. Os resultados encontrados foram comparados com dados encontrados na literatura. Com o sistema de espectrometria, foram gerados os espectros com a finalidade de determinar as tensões de pico relativas às tensões nominais escolhidas e caracterizar as Qualidades em Radiodiagnóstico determinadas anteriormente. O programa de controle de qualidade estabelecido possibilita o controle do funcionamento tanto dos instrumentos de medição (câmaras de ionização, medidor de tensão e corrente e espectrômetro), bem como do sistema de radiação X. Neste trabalho também foi sugerida a periodicidade de realização de cada um dos testes. / The objective of this work was to study the behavior of the mainly X ray equipment calibration laboratory of IPEN, operated in the range from 25 kV to 150 kV using a PTW non invasive meter, model DiavoltTM, and an ORTEC spectrometry system, model NOMAD-PLUS 92X, for the establishment of a quality control programme. The Diavolt meter was used for measurements of air kerma, peak voltage and practical peak voltage. The measurements were made varying parameters such as electrical current, X radiation quality for radiation diagnostic, angulations of the meter and its distance in relation to the focal spot of the X ray tube. The results were compared with data found in the literature. Several spectra were generated with the spectrometer system with the purpose of determine the peak voltage in function of the nominal voltage and to characterize the radiation qualities for radiation diagnostic previously determined. The established quality control programme enables the management of the appropriate functioning of the measurement instruments (ionization chambers, voltage and current meter and spectrometer) as well as of the X radiation system. This work also has proposed a time interval to run each one of the tests.
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