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<p>Safety assessment is a rational and systematic process for assessing the risk associated with the usage of a product. While the safety assessment process is important even when making a simple product, the true importance of this process comes into light when designing for example an aircraft, where a failure could possibly lead to the loss of human lives. However,even though this process is vital for certain industries, it is plagued by a lack of tools. The existing tools are focused on specific parts of the process and do not make use of work done in earlier steps of the process which often means that the safety engineer needs to manually do work that could have been calculated automatically from information that is already present from an earlier step in the process.</p><p>This thesis shows that by creating a model of the product that can be present and augmented throughout every step in the process, many calculations that are currently done by hand can be automated or semi-automated by examining this shared model. The thesis proposes a specification for a modeling formalism that is simple enough to be used as early as the requirements phase of a project, but powerful enough to provide important information all the way throughout the safety assessment process.</p><p>The thesis also specifically shows how this model can be used to help in the creation and updating process of Failure Mode and Effects Analysis (FMEA) documents as a proof-of concept implementation based on Sörman Information AB’s product “Uptime BPC Standard”.Algorithms for synchronizing between the model and the FMEA representation, as well as algorithms for automatically calculating the next level effect and global level effect of failure modes based on the hierarchy and connections made in the model are also presented.</p><p>The prototype implementation shows that even though the entire safety assessment process cannot be automated it is possible to extract information from the model by analyzing its hierarchy and connections. While more work still needs to be done before the entire safety assessment process can be encompassed, the initial results shows that the proposed modeling formalism allows us to create models from which relevant information that can be used to support the safety assessment process can be calculated.</p>

Safety is considered as one of the most important areas in future research and development within the automotive industry. New functionality, such as driver support and active/passive safety systems are examples where development mainly focuses on safety. At the same time, the trend is towards more complex systems, increased software dependence and an increasing amount of sensors and actuators, resulting in a higher risk associated with software and hardware failures. In the area of functional safety, standards such as ISO 26262 assess safety mainly focusing on qualitative assessment techniques, whereas usage of quantitative techniques is a growing area in academic research. This thesis considers the field functional safety, with the emphasis on how hardware and software failure probabilities can be used to quantitatively assess safety of a system/function. More specifically, this thesis presents a method for quantitative safety assessment using Bayesian networks for probabilistic modeling. Since the safety standard ISO 26262 is becoming common in the automotive industry, the developed method is adjusted to use information gathered when implementing this standard. Continuing the discussion about safety, a method for modeling faults and failures using Markov models is presented. These models connect to the previous developed Bayesian network and complete the quantitative safety assessment. Furthermore, the potential for implementing the discussed models in the Modelica language is investigated, aiming to find out if models such as these could be useful in practice to simplify design work, in order to meet future safety goals.

Using microsimulation software, with a focus on VISSIM, the analysis of different applications of merge concepts through delay and safety is presented in this thesis. In order to appropriately draw conclusions and usage trends of different merge concepts from the microsimulation software, early merge, late merge, and signal merge were first explored in a thorough literature review. While focusing primarily on delay, queues, and safety, this thesis essentially provides an introduction to determining the ideal merge concept on freeway work zones for varying roadway configurations, roadway conditions, and user demands, among other factors. In addition to delay and queuing analysis completed using VISSIM, the Federal Highway Administration’s Surrogate Safety Assessment Model (SSAM) was used to address the effects of implementing signal merge on rear-end and lane-change conflicts. Compiling the VISSIM microsimulation outputs and SSAM signal merge safety outputs, general conclusions and decisions were provided. While this thesis provides determinations of ideal merge concepts for a variety of cases, it is important for the next researcher to assess some of the assumptions that were made, to ensure that they would not significantly affect the results and analysis. / text

Safety assessment is a rational and systematic process for assessing the risk associated with the usage of a product. While the safety assessment process is important even when making a simple product, the true importance of this process comes into light when designing for example an aircraft, where a failure could possibly lead to the loss of human lives. However,even though this process is vital for certain industries, it is plagued by a lack of tools. The existing tools are focused on specific parts of the process and do not make use of work done in earlier steps of the process which often means that the safety engineer needs to manually do work that could have been calculated automatically from information that is already present from an earlier step in the process. This thesis shows that by creating a model of the product that can be present and augmented throughout every step in the process, many calculations that are currently done by hand can be automated or semi-automated by examining this shared model. The thesis proposes a specification for a modeling formalism that is simple enough to be used as early as the requirements phase of a project, but powerful enough to provide important information all the way throughout the safety assessment process. The thesis also specifically shows how this model can be used to help in the creation and updating process of Failure Mode and Effects Analysis (FMEA) documents as a proof-of concept implementation based on Sörman Information AB’s product “Uptime BPC Standard”.Algorithms for synchronizing between the model and the FMEA representation, as well as algorithms for automatically calculating the next level effect and global level effect of failure modes based on the hierarchy and connections made in the model are also presented. The prototype implementation shows that even though the entire safety assessment process cannot be automated it is possible to extract information from the model by analyzing its hierarchy and connections. While more work still needs to be done before the entire safety assessment process can be encompassed, the initial results shows that the proposed modeling formalism allows us to create models from which relevant information that can be used to support the safety assessment process can be calculated.

Recentemente, na indústria naval, a normatização por sociedades classificadoras e pela IMO (International Maritime Organization) tem apresentado uma mudança paulatina, migrando dos procedimentos prescritivos para uma estrutura regulatória baseada em risco. Tal perspectiva oferece algumas vantagens para operadores e armadores (empresas que exploram comercialmente as embarcações): 1) maior capacidade de incorporar projetos inovadores, tecnicamente superiores, a custos aceitáveis; 2) maior confiança quanto à segurança; 3) melhor entendimento de eventos de periculosidade, dos riscos enfrentados em novos projetos e de medidas de mitigação. Especificamente no setor petrolífero, a análise, a avaliação e o gerenciamento de risco são vitais, em face da potencial gravidade dos acidentes no que diz respeito à vida humana, ao meio-ambiente e ao patrimônio. Dado que a maior parte dos acidentes nesta área são motivados por fatores humanos, o propósito deste trabalho é apresentar uma metodologia e técnicas eficientes de análise de confiabilidade humana aplicáveis a esta indústria. Durante as últimas décadas, se desenvolveram várias técnicas para o estudo quantitativo da confiabilidade humana. Na década de oitenta foram desenvolvidas técnicas que modelam o sistema por meio de árvores binárias, não permitindo a representação do contexto em que as ações humanas ocorrem. Desta forma, a representação dos indivíduos, suas inter-relações e a dinâmica do sistema não podem ser bem trabalhadas pela aplicação destas técnicas. Estas questões tornaram latente a necessidade de aprimoramento dos métodos utilizados para a HRA (Human Reliability Analysis). No intuito de extinguir, ou ao menos atenuar, estas limitações alguns autores vêm propondo a modelagem do sistema por meio de Redes Bayesianas. Espera-se que a aplicação desta ferramenta consiga suprimir boa parte das deficiências na modelagem da ação humana com o uso de árvores binárias. Este trabalho apresenta uma breve descrição da aplicação de Redes Bayesianas na HRA. Além disto, apresenta a aplicação desta técnica no estudo da operação de um navio petroleiro, tendo como foco a quantificação da contribuição do fator humano em cenários de colisão. Por fim, são feitas considerações a respeito dos fatores que podem influenciar no desempenho humano e no risco de colisão. / Recently, in the naval industry, the normalization of classification societies and IMO (International Maritime Organization) has presented a gradual change, going from prescriptive procedures to a regulatory structure based on risk. That perspective offers some advantages to operators and constructors: 1) greater capacity to incorporate innovations in design, technically superiors, at acceptable cost; 2) greater confidence as to security; 3) better understanding of hazardous events, the risks faced by new projects and measures of mitigation. Specifically in the oil sector, the analyze, evaluation, and management of risk are vital, in face of the accidents severity potential in respect to human life, environment and property. Given that the greater part of the accidents on this sector is caused by human factors, the purpose of this dissertation is present a methodology and efficient techniques to HRA (Human Reliability Analysis) that can be applied in this industry. During the last decades many techniques were developed to a quantitative study of the human reliability. In the eighties were developed some techniques based in the modeling by means of binaries trees. These techniques do not consider the representation of the context in which the human actions occur. Thus, the representation of individuals, their inter-relationships and dynamics of the system cannot be better worked by the application of these techniques. These issues became the improvement of the used methods for HRA a latent need. With the aim of extinguish, or attenuate at least, these weaknesses some authors proposed the modeling of the human system by means of Bayesians Network. It is expected that with the application of this tool can be suppressed great part of the deficiencies of the human action modeling by means of binaries trees. This work presents a brief description about the application of Bayesians Network in HRA. Additionally, is presented the application of this technique in the study of an oil tanker operation, focusing in the human factor quantification in scenarios of collision. Besides, are presented some considerations about the factors that can influence the human performance and the collision risk.

Recentemente, na indústria naval, a normatização por sociedades classificadoras e pela IMO (International Maritime Organization) tem apresentado uma mudança paulatina, migrando dos procedimentos prescritivos para uma estrutura regulatória baseada em risco. Tal perspectiva oferece algumas vantagens para operadores e armadores (empresas que exploram comercialmente as embarcações): 1) maior capacidade de incorporar projetos inovadores, tecnicamente superiores, a custos aceitáveis; 2) maior confiança quanto à segurança; 3) melhor entendimento de eventos de periculosidade, dos riscos enfrentados em novos projetos e de medidas de mitigação. Especificamente no setor petrolífero, a análise, a avaliação e o gerenciamento de risco são vitais, em face da potencial gravidade dos acidentes no que diz respeito à vida humana, ao meio-ambiente e ao patrimônio. Dado que a maior parte dos acidentes nesta área são motivados por fatores humanos, o propósito deste trabalho é apresentar uma metodologia e técnicas eficientes de análise de confiabilidade humana aplicáveis a esta indústria. Durante as últimas décadas, se desenvolveram várias técnicas para o estudo quantitativo da confiabilidade humana. Na década de oitenta foram desenvolvidas técnicas que modelam o sistema por meio de árvores binárias, não permitindo a representação do contexto em que as ações humanas ocorrem. Desta forma, a representação dos indivíduos, suas inter-relações e a dinâmica do sistema não podem ser bem trabalhadas pela aplicação destas técnicas. Estas questões tornaram latente a necessidade de aprimoramento dos métodos utilizados para a HRA (Human Reliability Analysis). No intuito de extinguir, ou ao menos atenuar, estas limitações alguns autores vêm propondo a modelagem do sistema por meio de Redes Bayesianas. Espera-se que a aplicação desta ferramenta consiga suprimir boa parte das deficiências na modelagem da ação humana com o uso de árvores binárias. Este trabalho apresenta uma breve descrição da aplicação de Redes Bayesianas na HRA. Além disto, apresenta a aplicação desta técnica no estudo da operação de um navio petroleiro, tendo como foco a quantificação da contribuição do fator humano em cenários de colisão. Por fim, são feitas considerações a respeito dos fatores que podem influenciar no desempenho humano e no risco de colisão. / Recently, in the naval industry, the normalization of classification societies and IMO (International Maritime Organization) has presented a gradual change, going from prescriptive procedures to a regulatory structure based on risk. That perspective offers some advantages to operators and constructors: 1) greater capacity to incorporate innovations in design, technically superiors, at acceptable cost; 2) greater confidence as to security; 3) better understanding of hazardous events, the risks faced by new projects and measures of mitigation. Specifically in the oil sector, the analyze, evaluation, and management of risk are vital, in face of the accidents severity potential in respect to human life, environment and property. Given that the greater part of the accidents on this sector is caused by human factors, the purpose of this dissertation is present a methodology and efficient techniques to HRA (Human Reliability Analysis) that can be applied in this industry. During the last decades many techniques were developed to a quantitative study of the human reliability. In the eighties were developed some techniques based in the modeling by means of binaries trees. These techniques do not consider the representation of the context in which the human actions occur. Thus, the representation of individuals, their inter-relationships and dynamics of the system cannot be better worked by the application of these techniques. These issues became the improvement of the used methods for HRA a latent need. With the aim of extinguish, or attenuate at least, these weaknesses some authors proposed the modeling of the human system by means of Bayesians Network. It is expected that with the application of this tool can be suppressed great part of the deficiencies of the human action modeling by means of binaries trees. This work presents a brief description about the application of Bayesians Network in HRA. Additionally, is presented the application of this technique in the study of an oil tanker operation, focusing in the human factor quantification in scenarios of collision. Besides, are presented some considerations about the factors that can influence the human performance and the collision risk.

Recent research studies have been conducted for automating the safety assessment process in order to identify risks and safety hazards on a job site without human intervention. Regardless of the benefits of automated assessment, safety planners still face challenges selecting applicable devices, methods, and algorithms for safety assessment. This is due to the fact that (1) such devices, methods, and algorithms typically have measurement and processing errors, (2) construction operations and sites are unique and complex, and (3) the impact of the errors is different depending on workspaces. The primary objective of this research is to develop an error impact analysis method to model data collection and data processing errors caused by image-based devices and algorithms and to analyze the impact of the errors for spatial safety assessment of earthmoving and surface mining activities. The literature review revealed the possible causes of accidents on earthmoving activities, investigated the spatial risk factors of these types of accident, and identified spatial data needs for safety assessment based on current safety regulations. Image-based data collection devices and algorithms for safety assessment were then evaluated. Analysis methods and rules for monitoring safety violations were also discussed. A testbed to model and simulate workspaces and related spatial safety violations was finally designed. Using the testbed, the impacts of image-based algorithm and device errors―more specifically, object identification and tracking errors―on the data collected and processed were investigated for the safety planning purpose. Field experiments assessed the feasibility of automated spatial data collection and analysis methods. Industrial project and safety experts verified the proposed safety rules and the testbed design. Computer simulations were conducted for testing the proposed testbed. The testbed was used to model several earthmoving operation scenarios, detect simulated safety violations using safety rules, and finally evaluate the impact of different object identification and tracking errors on the safety analyses. The result of this research could be used for improving site safety assessment and planning by assisting safety planners to understand workspaces and to evaluate errors related to the use of different image-based technologies for safety assessment of earthmoving and surface mining activities. / text

O desenvolvimento de novos modelos de pele e novas metodologias in vitro segue uma tendência mundial na busca pela redução ou substituição de testes em animais. Nesse contexto, kits de epiderme humana reconstruída (RHE) apresentam-se como uma plataforma promissoras para essa proposta e, alguns modelos encontram-se validados para ensaios de irritação e corrosão cutânea in vitro. Entretanto, em países como o Brasil, enfrentam-se questões alfandegárias e perda do material por perecibilidade, dificultando e até impedindo, a importação desses kits para utilização por parte das indústrias e laboratórios nacionais. Em contrapartida, o desenvolvimento de um modelo de RHE apresenta-se como um avanço tecnológico e ganho de autonomia para esses países. Assim, no capítulo 1 explorou-se o desenvolvimento de um modelo nacional de RHE (USP-RHE) que atendesse às exigências internacionais descritas no guia OECD 439. O modelo desenvolvido apresentou uma epiderme bem diferenciada e atendeu aos parâmetros de qualidade (histologia, viabilidade e função barreira) bem como da funcionalidade, a qual é expressa na capacidade de distinção entre irritantes e não irritantes, apresentando 85,7% de especificidade, 100% sensibilidade e 92,3% de acurácia quando comparada com a classificação in vivo obtida pelo ensaio do linfonodo local (LLNA). No capítulo 2, células monocíticas THP-1 em monocamada foram capazes de distinguir entre agentes sensibilizantes e não sensibilizantes por meio da expressão de CD86, CD54 e liberação de IL-8. Após a obtenção de RHE e THP-1 funcionais, um cross-talking foi estabelecido gerando uma RHE imunocompetente. A RHEI distinguiu satisfatoriamente entre agentes sensibilizantes e não sensibilizantes por meio da expressão de CD86 e CD54 na membrana das células THP-1. A liberação de IL-8 também foi avaliada na RHEI, mas, não demonstrou ser um bom indicador para a avaliação de sensibilização, ao contrário de IL-1&#945;, que distinguiu satisfatoriamente agentes sensibilizantes de não-sensibilizantes, mas não foi capaz de hierarquizá-los. No capítulo 3, avaliou-se o papel de interleucinas do tipo Th2 e da depleção de colesterol na membrana plasmática no desenvolvimento de características morfológicas e moleculares da dermatite atópica (DA) in vitro em um modelo de RHE. Os resultados demonstram que o uso de IL-4, IL-13 e IL-25 em combinação com a depleção de colesterol na membrana plasmática mimetiza in vitro, as principais características da DA. No capítulo 4, buscou-se avaliar os efeitos imunossupressores da radiação ultravioleta na RHEI. Os ensaios foram realizados em diferentes períodos de exposição, entretanto, não foi possível observar tais efeitos. Os resultados justificam-se pela ausência da liberação de IL-10 pelo RHE imunocompetente, por exemplo, e demonstram uma limitação do RHE imunocompetente para avaliações de inativação da reposta imune. Neste trabalho, concluímos que foi possível obter uma RHE competitiva, similar aos modelos internacionais validados e que pode ser utilizada como plataforma para ensaios de irritação e sensibilização cutânea, além de ser uma plataforma para estudos da dermatite atópica. No modelo é possível estudar a ativação do sistema imune, o que o torna promissor como uma plataforma para avaliação de resposta imunológica in vitro. Conclui-se, portanto, que os objetivos foram amplamente atendidos além de oferecermos um protocolo de livre acesso para reprodução por outros laboratórios e um modelo para validação futura. / The development of new in vitro skin models and new methodologies follows a global trend in search for reductions or replacement of animal testing. In this context, Reconstructed Human Epidermis kits (RHE) are presented as a promising platform in the search for alternative methods to animal use, and some models are validated for skin irritation and corrosion in vitro tests. However, in countries such as Brazil, who face customs issues and loss of material due to perishability, making it challenging and even compromising the importation of these kits for use by industries and laboratories. In contrast, the development of an RHE model is presented as a technological breakthrough and gain of autonomy for these countries. Thus, in Chapter 1 we explored the development of a national model of RHE (USP-RHE) that meet international requirements described in OECD TG 439. The developed model presented a well-differentiated epidermis and met the quality parameters, for instance, histology, viability, and barrier function as well as the functionality expressed in the capacity of screening between irritants and nonirritants, with 85.7 % of specificity, 100 % of sensitivity and 91.7% of accuracy in comparision to in vivo UN GHS classification from Local limph node assay (LLNA). In chapter 2, monocytic THP-1 cell line, as monolayers, were able to distinguish between sensitizers and non-sensitizers by expression of CD86, CD54, and IL-8 release. In this model, functional RHE and THP-1 were used in a cross-talking, and thus an immunocompetent RHE (RHEI) was generated. The RHEI has distinguished satisfactorily between sensitizers and non-sensitizers through CD86 and CD54 expression that was larger and more sensitive in this model. The release of IL-8 was also evaluated in RHEI, however, did not demonstrate to be a good parameter for this evaluation, unlike IL-1&#945;, which satisfactorily distinguished sensitizers from non-sensitizers, but was not able to hierarchize them. In chapter 3, we evaluated the role of Th2-related cytokines and plasma membrane cholesterol depletion (CD) in the development of atopic dermatitis (AD) morphological and molecular characteristics in an in vitro model of RHE. The results showed that combination of IL-4, IL-13 and IL-25 in combination with CD can reproduce the major features of AD in vitro. In Chapter 4, we sought to evaluate the ultraviolet radiation-induced immunosuppressive effects in RHE. The tests were performed at different times. However, it was not possible to observe such effects. The results are justified by the absence of IL-10 release by RHEI, for example, and show a limitation of RHEI for rating inactivation of the immune response. In this work, we conclude that it was possible to obtain a competitive RHE similar to the validated international models that can be used as a platform for irritation and skin sensitization tests, besides being a platform for the study of atopic dermatitis. Using this model is possible to explore the activation of immune system, which makes it promising as a platform for the evaluation of immune response in vitro. We conclude, therefore, that the objectives have been met as well as it is offering an open source protocol for breeding by other laboratories, thus offering the RHE model developed here for future validation tests.

Probabilistic Safety Assessment (PSA) is a systematic and comprehensive methodology to evaluate risks associated with a complex engineered technological entity. The information provided by PSA has been increasingly implemented for regulatory purposes but rarely used in providing information for operation and maintenance activities. As one of the key parts in PSA, Fault Tree Analysis (FTA) attempts to model and analyze failure processes of engineering and biological systems. The fault trees are composed of logic diagrams that display the state of the system and are constructed using graphical design techniques. Risk Importance Measures (RIMs) are information that can be obtained from both qualitative and quantitative aspects of FTA. Components within a system can be ranked with respect to each specific criterion defined by each RIM. Through a RIM, a ranking of the components or basic events can be obtained and provide valuable information for risk-informed decision making. Various RIMs have been applied in various applications. In order to provide a thorough understanding of RIMs and interpret the results, they are categorized with respect to risk significance (RS) and safety significance (SS) in this thesis. This has also tied them into different maintenance activities. When RIMs are used for maintenance purposes, it is called risk-informed maintenance. On the other hand, the majority of work produced on the FTA method has been concentrated on failure logic diagrams restricted to the direct or implied use of AND and OR operators. Such systems are considered as coherent systems. However, the NOT logic can also contribute to the information produced by PSA. The importance analysis of non-coherent systems is rather limited, even though the field has received more and more attention over the years. The non-coherent systems introduce difficulties in both qualitative and quantitative assessment of the fault tree compared with the coherent systems. In this thesis, a set of RIMs is analyzed and investigated. The 8 commonly used RIMs (Birnbaum‘s Measure, Criticality Importance Factor, Fussell-Vesely Measure, Improvement Potential, Conditional Probability, Risk Achievement, Risk Achievement Worth, and Risk Reduction Worth) are extended to non-coherent forms. Both coherent and non-coherent forms are classified into different categories in order to assist different types of maintenance activities. The real systems such as the Steam Generator Level Control System in CANDU Nuclear Power Plant (NPP), a Gas Detection System, and the Automatic Power Control System of the experimental nuclear reactor are presented to demonstrate the application of the results as case studies. / UOIT