The science of system safety provides a structured guideline for managers to follow in order to ensure safe operations, but it does not ensure against deviations from such guidelines. This responsibility lies with management. Engineering managers must be able to dictate and track safety requirements throughout product development, deployment, and operation by treating system safety as an integrated engineering discipline. It is not feasible to expect the technical teams to integrate safety into designs unless safety requirements are considered a design metric just as cost and performance. Therefore, the traditional method of employing a separate safety department to address safety requirements is not sufficient. This responsibility must be given to all technical departments and levied as a design requirement. / text

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Thesis (Ph. D.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; 1 v. (various pagings) : ill. (some col.). Vita. Includes abstract. Includes bibliographical references.

This thesis aims to solicit and elicit the view of experienced system safety analysts in the applicability and use of STPA, a hazard analysis derived from the STAMP-framework. The increase in complexity in systems elevates the chance of hazards and risks being obfuscated. Thus, the intention is to expand, deepen and theorize about the STPA-methodology in relation to the role of system safety analysts in Sweden. The results show that the greatest use of STPA might lie in integrating the desired procedural steps with the hazard analysis techniques used today. This is due to individual capabilities, guidance in identification and evaluation of risks, as well as the reductionistic perspective that prevails in society today. Unlike STPA’s claim for completeness, the impression of the system analysts is that absolute safety can never be guaranteed.

An approach for robust design based on stochastic expansions is investigated. The research consists of two parts : 1) stochastic expansions for uncertainty propagation and 2) adaptive sampling for Pareto front approximation. For the first part, a strategy based on the generalized polynomial chaos (gPC) expansion method is developed. Second, in order to alleviate the computational cost of approximating the Pareto front, two strategies based on adaptive sampling for multi-objective problems are presented. The first one is based on the two aforementioned methods, whereas the second one considers, in addition, two levels of fidelity of the uncertainty propagation method.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 231-238).

<p>Space habitats will involve a complex and tightly coupled combination of hardware, software, and humans, while operating in challenging environments that pose many risks, both known and unknown. It will not be possible to design habitats that are immune to failure, nor will it be possible to foresee all possible failures. Rather than aiming for designs where “failure is not an option”, habitats must be resilient to disruptions. We propose a control-theoretic approach to resilient design for space habitats based on the concept of safety controls from system safety engineering. We model disruptions using a state and trigger model, where the space habitat is in one of three distinct states at each time instance: nominal, hazardous, or accident. The habitat transitions from a nominal state to hazardous states via disruptions, and further to hazardous and accident states via triggers. We develop an approach for identifying safety controls that considers these disruptions, hazardous states, and identifies control principles and their possible control flaws. We use safety controls as ways of preventing a system from entering or remaining in a hazardous or accident state. We develop a safety control option space for the habitat, from which designers can select the set of safety controls that best meet resilience, performance, and other system goals. We show how our approach for identifying safety controls drives our control-theoretic approach for resilient design, and how that fits into the larger system safety engineering process. To identify and assess hazards, we use a database and create a network format that stores the relationships between different disruptions and hazardous states for an example space habitat. We use this database in combination with traditional hazard assessment techniques to prioritize control of possible disruptions and hazardous states. To mitigate hazards, we develop a safety control option space that contains safety controls that either prevent transition to hazardous states or return the habitat to a nominal state. We use generic safety controls, or the principle of control, to generate new safety controls as our set of disruptions and hazardous states grows, and store these in the database. Lastly, we evaluate our mitigation techniques using our control effectiveness metric, a metric intended to assess how well a safety control addresses the hazardous state or disruption that it is designed for. Our control-theoretic approach is one way in which we can complete the system safety engineering process for a space habitat system and can provide design guidance for the development of resilient space habitats.</p>

O avanço recente da tecnologia na área de sistemas digitais representa uma grande oportunidade para realizar um importante progresso em diversos aspectos dos sistemas de controle e proteção tradicionais. No entanto, os requisitos provenientes do uso intensivo de software em sistemas críticos de segurança, aumenta a demanda por uma abordagem adequada que possa ser baseada na experiência nesta área. Apesar de vários modelos de capacidade de maturidade estarem em constante desenvolvimento, ainda é um desafio estabelecer uma forma coerente para a melhoria e avaliação do processo de desenvolvimento de software. O objetivo desta pesquisa é propor um método para obtenção de perfis de capacidade baseados na aplicação do modelo de referência brasileiro para melhoria do processo de software MR-MPS, em conjunto com a extensão de segurança do modelo de capacidade e maturidade CMMI-DEV +SAFE, embasado pela percepção de especialistas em segurança por meio da aplicação de um modelo de decisão por múltiplos critérios. / The recent technology advance in the digital systems area represents a great opportunity to make important progress in many aspects of traditional control and protection systems. However, requirements derived from the intensive use of software in safety critical systems raises the demand for a suitable approach that can be based on the expertise in this area. Although a number of capability maturity models have been in constant development, it is still challenging to establish a coherent path for software process improvement and evaluation. The goal of this research work is to propose a method for building capability profiles based on the application of the Brazilian Reference Model for Software Process Improvement MR-MPS, along with the Capability Maturity Model for Development safety extension CMMI-DEV +SAFE, supported by safety engineers insight through the application of a multi criteria decision model.

O avanço recente da tecnologia na área de sistemas digitais representa uma grande oportunidade para realizar um importante progresso em diversos aspectos dos sistemas de controle e proteção tradicionais. No entanto, os requisitos provenientes do uso intensivo de software em sistemas críticos de segurança, aumenta a demanda por uma abordagem adequada que possa ser baseada na experiência nesta área. Apesar de vários modelos de capacidade de maturidade estarem em constante desenvolvimento, ainda é um desafio estabelecer uma forma coerente para a melhoria e avaliação do processo de desenvolvimento de software. O objetivo desta pesquisa é propor um método para obtenção de perfis de capacidade baseados na aplicação do modelo de referência brasileiro para melhoria do processo de software MR-MPS, em conjunto com a extensão de segurança do modelo de capacidade e maturidade CMMI-DEV +SAFE, embasado pela percepção de especialistas em segurança por meio da aplicação de um modelo de decisão por múltiplos critérios. / The recent technology advance in the digital systems area represents a great opportunity to make important progress in many aspects of traditional control and protection systems. However, requirements derived from the intensive use of software in safety critical systems raises the demand for a suitable approach that can be based on the expertise in this area. Although a number of capability maturity models have been in constant development, it is still challenging to establish a coherent path for software process improvement and evaluation. The goal of this research work is to propose a method for building capability profiles based on the application of the Brazilian Reference Model for Software Process Improvement MR-MPS, along with the Capability Maturity Model for Development safety extension CMMI-DEV +SAFE, supported by safety engineers insight through the application of a multi criteria decision model.

This thesis examines the application of Systems-Theoretic Accident Model and Processes (STAMP) in healthcare and the analysis of patient safety incidents. Healthcare organisations have a responsibility for the safety of the patients they are treating. This includes the avoidance of unintended or unexpected harm to people during the provision of care. Patient safety incidents, that is adverse events where patients are harmed, are investigated and analysed as accidents are in other safety-critical industries, to gain an understanding of failure and to generate recommendations to prevent similar incidents occurring in the future. However, there is some dissatisfaction with the current quality of incident analysis in healthcare. There is dissatisfaction with the recommendations that are generated from healthcare incident analysis which are felt to produce weak and ineffective remedial actions, often including retraining of individuals and small policy change. Issues with current practice have been linked to the use of Root Cause Analysis (RCA), an analysis method that often results in the understanding of an accident as being the result of a linear chain of events. This type of simple linear approach has been the target of criticism in safety science research and is not felt to be effective in the analysis of incidents in complex systems, such as healthcare. Research in accident analysis methods has developed from a focus on technical failure and individual human actions to consideration of the interactions between people, technology and the organisation. Accident analysis methods have been developed that guide investigations to consideration of the whole system and interactions between system components. These system approaches are judged to be superior to simple linear approaches by the research community, however, they are not currently used in healthcare incident investigation practice. The systems approach of STAMP is felt to be a promising method for the improvement of healthcare incident analysis. STAMP strongly embodies the concepts of systems theory and analyses human decision-making. The application of STAMP in healthcare was investigated through three case studies, which applied STAMP in: 1. The analysis of the large-scale organisational failure at Mid-Staffordshire NHS Trust between 2005-2009. 2. The analysis of a common small-scale hospital-based medication prescription error. 3. The analysis of patient suicide in the community-based services of a Mental Health Trust. The effectiveness of the STAMP applications was evaluated with feedback from healthcare stakeholders on the usability and utility of STAMP and discussion of the STAMP applications against criteria for accident analysis models and methods. Healthcare stakeholders were generally positive about the utility of STAMP, finding it to provide a system view and guide consideration of interactions between system components. They also felt it would help them generate recommendations and were positive about the future application of STAMP in healthcare. However, many felt it to be a complicated method that would need specialist expertise to apply. The STAMP applications demonstrated the ability of STAMP to consider the whole system and guide an analysis to the generation of recommendations for system measures to prevent future incidents. From the findings of the research, recommendations are made to improve STAMP and to assist future applications of STAMP in healthcare. The research also discusses the other factors that influence incident analysis beyond that of the analytical approach used and how these need to be considered to maximise the effectiveness of STAMP.