O Transtorno de Ansiedade Social (TAS) é caracterizado pelo medo acentuado ou persistente de situações nas quais o individuo poderia sentir vergonha, levando ao comportamento de esquiva fóbica. Contudo, ainda é pouco diagnosticado, devido às dificuldades em perceber suas características como sintomas. Desse modo, a validação de instrumentos para rastreamento do TAS são de grande importância para auxiliar no diagnóstico e conduta. Dentre os instrumentos disponíveis na literatura, a Escala de Ansiedade Social de Liebowitz (LSAS) tem sido a mais utilizada mundialmente, seja em situações clínicas ou de pesquisa, porém para uso no contexto brasileiro, este instrumento não foi consistentemente validado. Assim, o objetivo deste estudo é aferir as qualidades psicométricas de validade (concorrente, divergente e discriminativa) e fidedignidade da LSAS-SR, traduzida para o português do Brasil, em sua versão auto-aplicada, em uma amostra de universitários da população geral (N=413) e em uma amostra clínica de TAS (N=252). Para tanto, foram coletados dados com universitários de duas instituições do interior do estado de São Paulo. Foram utilizados instrumentos para avaliação específica do TAS e de seus subtipos e outros para avaliação de constructos correlacionados ao TAS, tais como, ansiedade geral, prejuízos funcionais, depressão e abuso de álcool, além da LSAS-SR e um questionário de identificação. A LSAS-SR apresentou excelente consistência interna (=0,90-0,96). A validade convergente com escalas específicas para avaliação do TAS apresentou correlações que variam de 0,33 a 0,84. Com a escala que avalia aspectos específicos do TAS (falar em púbico) as correlações foram fracas e pouco significativas, sendo que com a escala de ansiedade geral esses valores foram de 0,21 a 0,57, classificada como fraca a moderada. Apresentou correlações moderadas, na maioria dos casos, com construtos correlacionados, tais quais depressão (0,36-0,52) e prejuízo funcional (0,30-0,72). Foi observada também adequada capacidade de discriminação da escala no que tange a diferenciação casos e não-casos (S=0,96, E=0,80). Na análise fatorial exploratória apontou inicialmente uma solução de 12 fatores. Testaram-se também soluções de três, quatro e cinco fatores, sendo que os mesmos foram compostos por agrupamentos de itens diferentes dos estudos prévios. A análise fatorial confirmatória também não replicou os achados prévios, sinalizando, tal como encontrado na literatura, a dificuldade em conseguir-se uma estrutura fatorial de consenso, comum às diversas culturas nas quais o instrumento foi estudado. Para avaliação da fidedignidade teste-reteste, foi calculado o Coeficiente de Correlação Intraclasse (0,81) e de Pearson (0,82) os quais mostram-se satisfatórios. Os presentes achados vão ao encontro de estudos internacionais que certificam às excelentes qualidades psicométricas da LSAS-SR. / Social Anxiety Disorder (SAD) is characterized by the sharp or persistent fear of situations in which the individual could feel shame, leading to a behavior of phobic avoidance. However, it is still little diagnosed, due to the difficulty in recognizing its characteristics as symptoms. Therefore, the validation of instruments to screening SAD is highly important to help in the diagnosis and treatment. Among the instruments available in the literature, Liebowitz Social Anxiety Scale (LSAS) has been the most used worldwide, being in clinical or of research situations. However, in the Brazilian context the use of this instrument has not been consistently validated. Thus, the objective of this study is to verify the psychometric qualities of validity (convergent, divergent and discriminant) and reliability of LSAS-SR, translated into Portuguese, in its self-reported version, in a sample of university students from the general population (N = 413) and in a clinical sample of SAD (N = 252). For this purpose, data from university students of two institutions of the interior of the state of São Paulo were collected. They used instruments for specific evaluation of SAD and of their subtypes and others for evaluation of constructs correlated to SAD, such as general anxiety, functional impairment, depression and alcohol abuse in addition to LSAR-SR and an identification questionnaire. LSAS-SR showed excellent internal consistency (=0.90-0.96). The convergent validity with specific scales for the SAD assessment presented correlations that ranged from 0.33 to 0.84. With the scale that evaluates specific aspects of the SAD (to speak in public) the correlations were weak and insignificant and with the general scale of anxiety these values ranged from 0.21 to 0.57, being classified as weak to moderate. It presented moderate correlations, in most cases, with correlated constructs, such as depression (0.36 0.52) and functional impairment (0.30 0.72). It was also observed adequate capacity of discrimination of the scale concerning the differentiation between cases and non-cases (S=0.96, E=0.80). Initially, the exploratory factorial analysis pointed the solution of 12 factors. The models with three, four and five factors were tested too, howsoever they were composed of clusters of different items compared with the original studies. The confirmatory factorial analysis did not replicate previous findings, signaling, as found in the literature, the difficulty in getting a factorial structure of consensus, common to several cultures where the instrument was studied. For the evaluation of test-retest reliability the Interclass Correlation (0.81) and the Pearson (0.82) Coefficients were calculated. Both demonstrated to be satisfactory. The present findings are aligned with international studies that certify the excellent psychometric qualities of LSAS-SR.

Os estudos de confiabilidade e disponibilidade encontram grandes aplicações no meio industrial. Neste trabalho é avaliada sob esta ótica um parque de uma indústria têxtil com diversas unidades de máquinas retorcedeiras, que realizam uma etapa do processo de produção de fios de nylon conhecido como retorção. Este processo consiste em torcer dois fios um contra o outro, dando origem a um fio duplo. Estas máquinas contam com dezenas de componentes que podem apresentar falhas. Ao longo de um período, foi colhido um banco de dados que foi tomado como base para este estudo. Este banco de dados foi filtrado, processo que à primeira vista pode parecer simples mas se não for feito criteriosamente pode comprometer toda a seqüência do trabalho. Após a definição de um procedimento para a validação de um modelo, são determinadas as confiabilidades com base nos dados de falha, e mantenabilidades com base nos dados de reparo, para os diversos modos de falha considerados. A partir de então, são feitas algumas simulações do comportamento da disponibilidade. Verifica-se quais são os modos de falha críticos e quais os seus impactos. Investigações adicionais são feitas, revelando alguns comportamentos não esperados. São então dadas orientações para a definição das políticas de manutenção e sugestões de onde atacar eventuais esforços de melhoria. O modelo de simulação é utilizado por final para verificar os resultados de uma possível melhoria futura no modo de falha mais crítico. Ao final, são apresentadas as conclusões do trabalho e recomendações para estudos futuros. / Reliability and availability studies find themselves very useful among industries. In the present work, the machinery of a textile company is evaluated concerning this topic. This company uses machines that perform the process of twisting, which is one step in the whole process of producing nylon textile yarns. In the twisting, two single yarns are twisted against each other, producing a double yarn. In these machines there are dozens of parts that may fail. During a period of time, data was collected to this work. This data are then filtered. This may seems simple at a first sight, but it may compromise the whole work if not done in a carefully way. In the sequence a procedure to validate a model is established. Right after, the reliabilities are evaluated, based on the failures data, to all considered failures modes. Maintainabilities are also evaluated, based on repair data. Then, some simulations are made upon the availability behavior. The critical failure modes are found and their impacts are showed. Additional investigations are done, and this leads to some behaviors that are not expected. Some guidelines are given to the maintenance policy definition, and to where eventually improvement efforts should focus on. Finally, the simulation model is used to check the results of a possible future improvement in the most critical failure mode. At the end, conclusions and recommendations to future works are presented.

Finally, we formulate the relationship between code coverage and fault detection. Although our two current models are in simple mathematical formats, they can predict the percentage of fault detected by the code coverage achieved for a certain test set. We further incorporate such formulation into traditional reliability growth models, not only for fault-tolerant software, but also for general software system. Our empirical evaluations show that our new reliability model can achieve more accurate reliability assessment than the traditional Non-homogenous Poisson model. / Furthermore, to investigate some "variants" as well as "invariants" of fault-tolerant software, we perform an empirical investigation on evaluating reliability features by a comprehensive comparison between two projects: our project and NASA 4-University project. Based on the same specification for program development, these two projects encounter some common as well as different features. The testing results of two comprehensive operational testing procedures involving hundreds of thousands test cases are collected and compared. Similar as well as dissimilar faults are observed and analyzed, indicating common problems related to the same application in both projects. The small number of coincident failures in the two projects, nevertheless, provide a supportive evidence for N-version programming, while the observed reliability improvement implies some trends in the software development in the past twenty years. / Motivated by the lack of real-world project data for investigation on software testing and fault tolerance techniques together, we conduct a real-world project and engage multiple programming teams to independently develop program versions based on an industry-scale avionics application. Detailed experimentations are conducted to study the nature, source, type, detectability, and effect of faults uncovered in the program versions, and to learn the relationship among these faults and the correlation of their resulting failures. Coverage-based testing as well as mutation testing techniques are adopted to reproduce mutants with real faults, which facilitate the investigation on the effectiveness of data flow coverage, mutation coverage, and fault coverage for design diversity. / Next, we investigate the effect of code coverage on fault detection which is the underlying intuition of coverage-based testing strategies. From our experimental data, we find that code coverage is a moderate indicator for the capability of fault detection on the whole test set. But the effect of code coverage on fault detection varies under different testing profiles. The correlation between the two measures is high with exceptional test cases, but weak in normal testing. Moreover, our study shows that code coverage can be used as a good filter to reduce the size of the effective test set, although it is more evident for exceptional test cases. / Software permeates our modern society, and its complexity and criticality is ever increasing. Thus the capability to tolerate software faults, particularly for critical applications, is evident. While fault-tolerant software is seen as a necessity, it also remains as a controversial technique and there is a lack of conclusive assessment about its effectiveness. / Then, based on the preliminary experimental data, further experimentation and detailed analyses on the correlations among these faults and the relation to their resulting failures are studied. The results are further applied to the current reliability modeling techniques for fault-tolerant software to examine their effectiveness and accuracy. / This thesis aims at providing a quantitative assessment scheme for a comprehensive evaluation of fault-tolerant software including reliability model comparisons and trade-off studies with software testing techniques. First of all, we propose a comprehensive procedure in assessing fault-tolerant software for software reliability engineering, which is composed of four tasks: modeling, experimentation, evaluation and economics. Our ultimate objective is to construct a systematic approach to predicting the achievable reliability based on the software architecture and testing evidences, through an investigation of testing and modeling techniques for fault-tolerant software. / Cai Xia. / "September 2006." / Adviser: Rung Tsong Michael Lyu. / Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1715. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 165-181). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Industry and society are now aware of risk more than ever before. Organisations whose activities pose risk to individuals and society are accountable to manage and reduce risk to an acceptable level. In this regard, utilisation of Safety Instrumented Systems (SISs) as an independent protection layer is a practical method of achieving the required risk reduction. The role of a SIS is to maintain the safety of equipment under control by providing a safety-related function. The International Standards, IEC 61508/61511, provide a set of guidelines to promote consistency for implementation of SISs used for risk reduction. In accordance with IEC 61508, the performance of a SIS shall be established by computing the associated Probability of Failure on Demand (PFD) as a reliability measure using a suitable technique. The principal purpose of this research is to provide the basis for reliability assessment of redundant SISs affected by process demand as well as component failures. This dissertation introduces four new reliability models for redundant SISs subject to process demand for the first time using Markov analysis technique. The proposed reliability models 1 and 3 incorporates process demands in conjunction with Common Cause Failure (CCF) and evaluates their impacts on the reliability quantification of 1oo2 redundant configuration using different repair philosophies. In model 3, the proposed Markov model was also compared with the IEC 61508 approach for redundant SISs and a reliability improvement between 9% - 15% were observed. The model 2 on the other hand integrates the Dangerous Detected (DD) failure rates in the unavailability assessment of redundant SISs subject to process demand assuming that CCF does not occur. An additional reliability model was developed in this research for a 1oo3 redundant configuration subject to process demand excluding CCF and its construction was verified using partial verification method. Furthermore, a generic framework for reliability assessment of 1oon redundant SISs is provided in this thesis in conjunction with some guidelines for future researchers as how to conduct reliability assessment of SISs subject to process demands. The accuracy of the proposed Markov models is verified for industrial application case studies. It is demonstrated that the proposed approach provides a sufficiently robust result for all demand rates, demand durations, common cause failures, dangerous detected and undetected failure and associated repair rates for SISs. The effectiveness of the proposed models offers a robust opportunity to conduct reliability assessment of redundant SISs subject to process demands.

Thesis. 1975. M.S.--Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science. / Includes bibliographical references. / by Edward Charles Giaimo, III. / M.S.

Diante da indisponibilidade de um instrumento específico de avaliação da qualidade de vida (QV) de pessoas com qualquer tipo de ferida, em nosso meio, o objetivo deste estudo foi construir e validar a versão feridas do Índice de Qualidade de Vida de Ferrans e Powers (IQVFP-VF). Inicialmente, o estudo recebeu autorização das autoras do instrumento original, aprovação pelo Comitê de Ética da EEUSP e autorizações dos campos para a coleta de dados. Classificado como do tipo metodológico, o estudo foi desenvolvido segundo os procedimentos teóricos, empíricos e analíticos, propostos por Pasquali, Os procedimentos teóricos incluíram a definição e análise dos itens por meio de revisão de literatura, avaliações de juizes (especialistas e pacientes) e pré-teste; os empíricos foram realizados por meio da aplicação do instrumento, resultante da etapa anterior, para análise de suas propriedades psicométricas, em amostras de teste (n=362), re-teste (n = 63) e validade convergente (n=179); e os analíticos, por meio das estratégias estatísticas destinadas às análises das propriedades psicométricas do instrumento final dos procedimentos teóricos. A confiabilidade foi obtida por meio da avaliação da consistência interna - CI (alfa de Cronbach 0,70) e da estabilidade do instrumento - duas semanas pós-teste (coeficiente de correlação intraclasse 0,70). Avaliaram-se a validade de conteúdo, pela concordância entre juizes ( 80%); a de critério concorrente, pela correlação entre os escores do item sua satisfação e dos domínios e instrumento total (coeficiente de correlação de Pearson ou Spearman 0,30); a validade de construto convergente, correlacionando-se os domínios e instrumento total do IQVFP-VF e WHOQOL-bref (esperando-se correlações moderadas a fortes 0,30 entre os domínios similares e < 0,30 entre os diferentes) e a validade de construto discriminante, comparando-se os escores dos domínios e instrumento total quanto a idade, número e duração da ferida e intensidade de dor, no momento e na última semana (Testes de Mann-Whitney, Kruskal-Wallis, t-Student e ANOVA). A análise fatorial confirmatória (AFC) foi testada pelo grau de correlação entre os itens e os domínios originais (saúde/funcionamento-SF; sócio-econômico-SE; psicológico e espiritual-PE e família-Fa) e medidas de ajuste de modelo (LISREL). A amostra foi composta de pacientes ambulatoriais com feridas, pertencentes a dezesseis instituições, que se enquadraram em critérios pré-estabelecidos. Os resultados mostram coeficientes alfa de Cronbach 0,90; 0,88; 0,65; 0,81; 0,55 para o instrumento total e domínios SF, SE, PE, Fa respectivamente, na avaliação da CI; para a estabilidade, encontraram-se correlações 0,83 (p < 0,000); para a validade concorrente, correlações de 0,28 a 0,69; para a validade convergente, correlações de 0,17 a 0, 60 e para a validade discriminante, correlações significativas entre: QV geral e número de feridas (p=0,047); PE e duração da ferida (p=0,017); SF (p= 0,043), SE (p= 0,008), PE (p= 0,000) e qualidade de vida geral (p=0,003) para as faixas etárias mais avançadas; e SE e a pior dor da semana anterior à entrevista (p = 0,015). À AFC sugeriu que o modelo é razoavelmente ajustado para o quatro domínios. Concluindo-se o estudo, pode-se considerar que o IQVFP-VF - como um instrumento específico e relacionado à saúde - é válido e tem confiabilidade atestada nos aspectos mais importantes para a população com feridas: a QV geral, a saúde e os aspectos psicológicos e espirituais / The scarcity of a specific tool to evaluate the quality of life (QOL) of persons with any kind of wounds, in our culture, lead to the development of this study. It aimed to develop and validate a wound version of the Ferrans & Powers QOL Index (QLI -WV). The study was authorized by the QLI authors and was approved by the Ethics Committee of Nursing College of the University of São Paulo and authorized by the institutions where data were collected. This methodological research was based on the procedures established by Paquali. The theoretical pole included the selection and analysis of the items to be included in the instrument (literature review, evaluations by specialists and patients committees and pre test). The empirical ones were developed through the application of the resulted instrument (from last step) to test sample (n=362), teste-retest sample (n=63) and convergent validity sample (n=179). And the analytical pole included the statistical strategies to analyse the instrument´s psychometric properties. The reliability was obtained through: internal consistency - IC (Cronbach´s alpha 0,70) and stability, two weeks after the first instrument apllication (Intraclass correlation coeficient 0,70). The content validity was analysed through the concordance level between judges ( 80%); the concurrent validity, through the correlation among the scores of the item your satisfaction and domains and overall QOL (Pearson or Spearman correlation coeficient 0,30); the convergent validity, through the correlation between the domains and overall QOL of QLI -WV and WHOQOL-bref (strong to moderate correlation between similar domains and weak between the different ones) and the discriminant validity through the comparison among the domains and total QOL and age, wound number and durability, and present and the worst last week pain (Mann Whitney, Kruskal-Wallis, t-Student and ANOVA tests). The confirmatory factor analysis (CFA) was tested by the correlation between the QLI-WV items and original domains (health & functioning - HF; socioeconomic - SE, psychological/spiritual - PS and family - Fa) and the adjustment measures model (LISREL). The sample was composed by outpatients who were assisted at 16 Health Services, and who met the pre established criteria. The results showed Cronbach´s alpha coeficients of 0.90; 0.88; 0.65; 0.81; 0.55 respectively for total QOL and domains (HF, SE, PS and Fa) for IC; r 0.83 (p < 0.000) for stability; r = 0.28 to 0.69 for concurrent validity; r = 0.17 to 0. 60 for convergent validity and significative correlation between: overall QOL and number of wounds (p=0.047); PS and wound durability (p=0.017); HF (p= 0.043), SE (p= 0.008), PS (p= 0.000) and overall QOL (p=0.003) for old patients; and SE and worst last week pain (p = 0.015). CFA suggested a reasonable fit for a four original subscale. The author concludes that QLI-WV - as a specific and health related QOL instrument - can be considered reliable and valid as it confirmed their psychometric properties, related to the most important wound care aspects as the total QOL, health and psychological and spiritual issues

O Transtorno de Ansiedade Social (TAS) é caracterizado pelo medo acentuado ou persistente de situações nas quais o individuo poderia sentir vergonha, levando ao comportamento de esquiva fóbica. Contudo, ainda é pouco diagnosticado, devido às dificuldades em perceber suas características como sintomas. Desse modo, a validação de instrumentos para rastreamento do TAS são de grande importância para auxiliar no diagnóstico e conduta. Dentre os instrumentos disponíveis na literatura, a Escala de Ansiedade Social de Liebowitz (LSAS) tem sido a mais utilizada mundialmente, seja em situações clínicas ou de pesquisa, porém para uso no contexto brasileiro, este instrumento não foi consistentemente validado. Assim, o objetivo deste estudo é aferir as qualidades psicométricas de validade (concorrente, divergente e discriminativa) e fidedignidade da LSAS-SR, traduzida para o português do Brasil, em sua versão auto-aplicada, em uma amostra de universitários da população geral (N=413) e em uma amostra clínica de TAS (N=252). Para tanto, foram coletados dados com universitários de duas instituições do interior do estado de São Paulo. Foram utilizados instrumentos para avaliação específica do TAS e de seus subtipos e outros para avaliação de constructos correlacionados ao TAS, tais como, ansiedade geral, prejuízos funcionais, depressão e abuso de álcool, além da LSAS-SR e um questionário de identificação. A LSAS-SR apresentou excelente consistência interna (=0,90-0,96). A validade convergente com escalas específicas para avaliação do TAS apresentou correlações que variam de 0,33 a 0,84. Com a escala que avalia aspectos específicos do TAS (falar em púbico) as correlações foram fracas e pouco significativas, sendo que com a escala de ansiedade geral esses valores foram de 0,21 a 0,57, classificada como fraca a moderada. Apresentou correlações moderadas, na maioria dos casos, com construtos correlacionados, tais quais depressão (0,36-0,52) e prejuízo funcional (0,30-0,72). Foi observada também adequada capacidade de discriminação da escala no que tange a diferenciação casos e não-casos (S=0,96, E=0,80). Na análise fatorial exploratória apontou inicialmente uma solução de 12 fatores. Testaram-se também soluções de três, quatro e cinco fatores, sendo que os mesmos foram compostos por agrupamentos de itens diferentes dos estudos prévios. A análise fatorial confirmatória também não replicou os achados prévios, sinalizando, tal como encontrado na literatura, a dificuldade em conseguir-se uma estrutura fatorial de consenso, comum às diversas culturas nas quais o instrumento foi estudado. Para avaliação da fidedignidade teste-reteste, foi calculado o Coeficiente de Correlação Intraclasse (0,81) e de Pearson (0,82) os quais mostram-se satisfatórios. Os presentes achados vão ao encontro de estudos internacionais que certificam às excelentes qualidades psicométricas da LSAS-SR. / Social Anxiety Disorder (SAD) is characterized by the sharp or persistent fear of situations in which the individual could feel shame, leading to a behavior of phobic avoidance. However, it is still little diagnosed, due to the difficulty in recognizing its characteristics as symptoms. Therefore, the validation of instruments to screening SAD is highly important to help in the diagnosis and treatment. Among the instruments available in the literature, Liebowitz Social Anxiety Scale (LSAS) has been the most used worldwide, being in clinical or of research situations. However, in the Brazilian context the use of this instrument has not been consistently validated. Thus, the objective of this study is to verify the psychometric qualities of validity (convergent, divergent and discriminant) and reliability of LSAS-SR, translated into Portuguese, in its self-reported version, in a sample of university students from the general population (N = 413) and in a clinical sample of SAD (N = 252). For this purpose, data from university students of two institutions of the interior of the state of São Paulo were collected. They used instruments for specific evaluation of SAD and of their subtypes and others for evaluation of constructs correlated to SAD, such as general anxiety, functional impairment, depression and alcohol abuse in addition to LSAR-SR and an identification questionnaire. LSAS-SR showed excellent internal consistency (=0.90-0.96). The convergent validity with specific scales for the SAD assessment presented correlations that ranged from 0.33 to 0.84. With the scale that evaluates specific aspects of the SAD (to speak in public) the correlations were weak and insignificant and with the general scale of anxiety these values ranged from 0.21 to 0.57, being classified as weak to moderate. It presented moderate correlations, in most cases, with correlated constructs, such as depression (0.36 0.52) and functional impairment (0.30 0.72). It was also observed adequate capacity of discrimination of the scale concerning the differentiation between cases and non-cases (S=0.96, E=0.80). Initially, the exploratory factorial analysis pointed the solution of 12 factors. The models with three, four and five factors were tested too, howsoever they were composed of clusters of different items compared with the original studies. The confirmatory factorial analysis did not replicate previous findings, signaling, as found in the literature, the difficulty in getting a factorial structure of consensus, common to several cultures where the instrument was studied. For the evaluation of test-retest reliability the Interclass Correlation (0.81) and the Pearson (0.82) Coefficients were calculated. Both demonstrated to be satisfactory. The present findings are aligned with international studies that certify the excellent psychometric qualities of LSAS-SR.

Made available in DSpace on 2015-04-22T22:11:20Z (GMT). No. of bitstreams: 1 Francisco Neto.pdf: 1178598 bytes, checksum: e8f75ba19e5b23d6cc92ff14731d7775 (MD5) Previous issue date: 2011-08-18 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The growing competition in the consumer market and the current global scenario of the electronics industry where products become increasingly complex, and its levels of quality and reliability required increasingly point to a direction in which the need to use techniques that assist in the construction of the reliability of a product from the earliest stages of its development is increasingly becomes indispensable. The reliability of a product is mainly affected by the existence of defects that are in a latent state, which, if not identified and treated, can manifest themselves as gross failures already in the hands of the consumer, while using the product. In order to diagnose the status of assets of a mechanical laboratory, there was a single case study of qualitative character, which we used a semi structured questionnaire to ask the managers, technicians and researchers in order to identify the degree of knowledge and interaction of these with the practices and maintenance policy. The results were analyzed according to the construct, and mostly convergent (63.15%), although considered fundamental issues differ (36.84%). Results showed a total loss of the maintenance history, because there were no data to be analyzed. In this sense, it is the tool to support FTA with the analysis of problems and clarify the fact that a maintenance problem in the climatic test equipment can mask results. The study revealed that although the company has money earmarked for maintenance of laboratory equipment, they are making the area a number of machines scrapped because no action is being developed in order to ensure smooth operation of the assets. / A crescente competição do mercado consumidor mundial e o atual cenário da indústria eletroeletrônica no qual os produtos tornam-se cada vez mais complexos, tendo seus índices de qualidade e confiabilidade cada vez mais exigidos, apontam para uma direção na qual a necessidade da utilização de técnicas que auxiliem na construção da confiabilidade de um produto desde as primeiras fases do seu desenvolvimento seja cada vez maior torna-se indispensável. A confiabilidade de um produto é afetada principalmente pela existência de defeitos que se encontram em um estado latente, os quais, se não identificados e tratados, podem se manifestar como falhas infantis, já em mãos do consumidor final, durante o uso do produto. Com o objetivo de diagnosticar a situação atual dos ativos de um laboratório de mecânica, foi realizado um estudo de caso único de cunho qualitativo, onde se utilizou um questionário semi estruturado para indagar os gestores, técnicos e pesquisadores da área, a fim de identificar o grau de conhecimento e interação dos mesmos com as práticas e política de manutenção. Os resultados foram analisados conforme o constructo, e em sua maioria, convergentes (63,15%), apesar de questões consideradas fundamentais divergirem (36,84%). Os resultados apontaram para uma perda total o histórico de manutenção, pois não haviam dados para serem analisados. Desta forma, apresentou-se a ferramenta FTA para corroborar com a análise dos problemas e esclarecer o fato de que um problema de manutenção nos equipamentos de ensaios climáticos pode mascarar resultados. O estudo revelou que apesar da empresa possuir verbas destinadas à manutenção de equipamentos de laboratório, os mesmos estão tornando a área um parque de máquinas sucateadas, pois nenhuma ação esta sendo desenvolvido no intuito de garantir o perfeito e contínuo funcionamento dos ativos.

Reliability and redundancy of safety-critical network systems is a paramount issue in system engineering. Be it in evaluating existing network systems or solving optimization problems for designing network systems, it is important to consider reliability and redundancy. This dissertation is in collaboration with AIRBUS Group, France, and they are very interest in the optimal design of safety-critical aircraft architecture systems which have to consider reliability and redundancy. To address the problem of optimally designing such systems, we chose to focus on one specific aircraft architecture system the door management system. It checks if all doors are properly closed and the cabin has the correct pressure. It is a safety-critical system since it is part of the pressurization system of an aircraft. To optimally design the DMS while considering reliability, a suitable reliability evaluation algorithm is necessary. In this dissertation, we begin by proposing a suitable reliability evaluation algorithm for a type of non series-parallel network system which includes the DMS and which can be used in an optimization model. The reliability evaluation algorithm is based on a simplification of the probability principle of inclusion-exclusion formula for intersections of unions. The simplification exploits the presence of many repeated events and has many fewer terms, which significantly reduces the number of operations needed. We compare its computational efficiency against the sum of disjoint products method KDH88 for a simple artificial example and for the DMS. Afterwards, we introduce the first MILP model for the DMS with k-redundancy. As the model is too difficult to be solved efficiently by standard MILP solvers, we discuss the issues of solving the model with general solving methods such as branch-and-bound and branch-and-price. We introduce specialized branching rules and new heuristics to solve the DMS problem with k-redundancy more efficiently and show results of computational tests which compare the specialized solving algorithms with general solving algorithms for example instances of the DMS problem. Lastly, we discuss the problems of considering reliability in MI(N)LP models for the DMS and how the new reliability evaluation algorithm can be used. In this discussion, we give different MI(N)LP models for the DMS problem with redundancy and reliability. Moreover, we propose a new heuristic for the DMS problem with redundancy and reliability. It is based on branch-and-bound, the Dantzig-Wolfe decomposition and on the new reliability evaluation algorithm. We show results of computational tests of the new heuristic for example instances of the DMS problem and discuss its validity.

In the future, the performance of the railway system must be improved to accommodate increasing passenger volumes and service quality demands. Track switches are a vital part of the rail infrastructure, enabling traffic to take different routes. All modern switch designs have evolved from a design first patented in 1832. However, switches present single points of failure, require frequent and costly maintenance interventions, and restrict network capacity. Fault tolerance is the practice of preventing subsystem faults propagating to whole-system failures. Existing switches are not considered fault tolerant. This thesis describes the development and potential performance of fault-tolerant railway track switching solutions. The work first presents a requirements definition and evaluation framework which can be used to select candidate designs from a range of novel switching solutions. A candidate design with the potential to exceed the performance of existing designs is selected. This design is then modelled to ascertain its practical feasibility alongside potential reliability, availability, maintainability and capacity performance. The design and construction of a laboratory scale demonstrator of the design is described. The modelling results show that the performance of the fault tolerant design may exceed that of traditional switches. Reliability and availability performance increases significantly, whilst capacity gains are present but more marginal without the associated relaxation of rules regarding junction control. However, the work also identifies significant areas of future work before such an approach could be adopted in practice.