Dissertations / Theses: 'SAFETY SYSTEMS'

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Bradley, Aaron R. "Safety analysis of systems /." May be available electronically:, 2007. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.

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Dreany, Harry Hayes. "Safety Engineering of Computational Cognitive Architectures within Safety-Critical Systems." Thesis, The George Washington University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10688677.

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This paper presents the integration of an intelligent decision support model (IDSM) with a cognitive architecture that controls an autonomous non-deterministic safety-critical system. The IDSM will integrate multi-criteria, decision-making tools via intelligent technologies such as expert systems, fuzzy logic, machine learning, and genetic algorithms.

Cognitive technology is currently simulated within safety-critical systems to highlight variables of interest, interface with intelligent technologies, and provide an environment that improves the system’s cognitive performance. In this study, the IDSM is being applied to an actual safety-critical system, an unmanned surface vehicle (USV) with embedded artificial intelligence (AI) software. The USV’s safety performance is being researched in a simulated and a real-world, maritime based environment. The objective is to build a dynamically changing model to evaluate a cognitive architecture’s ability to ensure safe performance of an intelligent safety-critical system. The IDSM does this by finding a set of key safety performance parameters that can be critiqued via safety measurements, mechanisms, and methodologies. The uniqueness of this research lies in bounding the decision-making associated with the cognitive architecture’s key safety parameters (KSPs). Other real-time applications (RTAs) that would benefit from advancing cognitive science associated with safety are unmanned platforms, transportation technologies, and service robotics. Results will provide cognitive science researchers with a reference for the safety engineering of artificially intelligent safety-critical systems.

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Reinhardt, Derek Wade. "Safety assurance of aviation systems." Thesis, University of York, 2013. http://etheses.whiterose.ac.uk/6208/.

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From review of historical projects, there is evidence that limitations in contemporary safety assurance approaches for software-dependent systems contribute to programmatic and certification difficulties, e.g. delays and risk retention. These difficulties arise particularly in relation to evaluating risk of systematic behavioural anomalies and evidence shortfalls or deficiencies. These findings question the effectiveness of current safety assurance approaches. Although these problems are general, this thesis is grounded in the context of Australian Defence Force aviation projects. Through analysing the purpose of safety assurance standards, this thesis establishes principles and guidelines for defining effective safety assurance frameworks for aviation systems. The principles and guidelines are used to define a novel integrated framework which is responsive to the specific challenges of military aviation systems acquisition. The framework qualifies knowledge of risks and uncertainty, focusing on product behaviour in the architectural context. It is based on evaluation of properties of architecture, including the prevention and tolerance of faults. Knowledge of product behaviours is informed by attributes of supporting evidence, and the tolerability of limitations in evidence. A key factor in the success of safety assurance standards, in an acquisition context, relates to their effectiveness for reducing uncertainty for supplier delivery of safety evidence across contracting processes. Thus this thesis also provides a method for contracting for the novel integrated framework. Evaluation of the principles, guidelines and framework has been conducted through peer review via workshop and survey questionnaire, analysis against real world aircraft architectures, analysis with respect to historical project data, a constructed example, anti-hypothesis analysis, and evaluation as an audit tool and contract evaluation aid on several projects. Evaluation on an actual project was not possible. A major factor identified in the effectiveness of safety assurance standards is how stakeholders are incentivised (or conversely discouraged) in decision making pertaining to product risk and evidence. This thesis shows that the novel integrated framework, through implementation of the principles and guidelines, could help to avoid the classes of project issues observed historically by enabling developers and assessors to focus on reasoning about the risks of behavioural properties of products, and in the production of evidence used to inform product behaviours. Further evaluation via application to actual projects is required to provide more definitive evidence of benefits and limitations.

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Masson, Lola. "Safety monitoring for autonomous systems : interactive elicitation of safety rules." Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30220.

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Un moniteur de sécurité actif est un mécanisme indépendant qui est responsable de maintenir le système dans un état sûr, en cas de situation dangereuse. Il dispose d'observations (capteurs) et d'interventions (actionneurs). Des règles de sécurité sont synthétisées, à partir des résultats d'une analyse de risques, grâce à l'outil SMOF (Safety MOnitoring Framework), afin d'identifier quelles interventions appliquer quand une observation atteint une valeur dangereuse. Les règles de sécurité respectent une propriété de sécurité (le système reste das un état sûr) ainsi que des propriétés de permissivité, qui assurent que le système peut toujours effectuer ses tâches. Ce travail se concentre sur la résolution de cas où la synthèse échoue à retourner un ensemble de règles sûres et permissives. Pour assister l'utilisateur dans ces cas, trois nouvelles fonctionnalités sont introduites et développées. La première adresse le diagnostique des raisons pour lesquelles une règle échoue à respecter les exigences de permissivité. La deuxième suggère des interventions de sécurité candidates à injecter dans le processus de synthèse. La troisième permet l'adaptation des exigences de permissivités à un ensemble de tâches essentielles à préserver. L'utilisation des ces trois fonctionnalités est discutée et illustrée sur deux cas d'étude industriels, un robot industriel de KUKA et un robot de maintenance de Sterela
An active safety monitor is an independent mechanism that is responsible for keeping the system in a safe state, should a hazardous situation occur. Is has observations (sensors) and interventions (actuators). Safety rules are synthesized from the results of the hazard analysis, using the tool SMOF (Safety MOnitoring Framework), in order to identify which interventions to apply for dangerous observations values. The safety rules enforce a safety property (the system remains in a safe state) and some permissiveness properties, ensuring that the system can still perform its tasks. This work focuses on solving cases where the synthesis fails to return a set of safe and permissive rules. To assist the user in these cases, three new features are introduced and developed. The first one addresses the diagnosis of why the rules fail to fulfill a permissiveness requirement. The second one suggests candidate safety interventions to inject into the synthesis process. The third one allows the tuning of the permissiveness requirements based on a set of essential functionalities to maintain. The use of these features is discussed and illustrated on two industrial case studies, a manufacturing robot from KUKA and a maintenance robot from Sterela

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Almarshed, Amer. "Improving Safety in Hajj." Digital Commons at Loyola Marymount University and Loyola Law School, 2016. https://digitalcommons.lmu.edu/etd/339.

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Sgueglia, John. "Managing design changes using safety-guided design for a safety critical automotive system." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/106224.

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Thesis: S.M. in Engineering and Management, Massachusetts Institute of Technology, School of Engineering, System Design and Management Program, Engineering and Management Program, 2015.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 95-99).
The use of software to control automotive safety critical functions, such as throttle, braking and steering has been increasing. The automotive industry has a need for safety analysis methods and design processes to ensure these systems function safely. Many current recommendations still focus on traditional methods, which worked well for electro-mechanical designs but are not adequate for software intensive complex systems. System Theoretic Accident Model and Process (STAMP) and the associated System Theoretic Process Analysis (STPA) method have been found to identify hazards for complex systems and can be effective earlier in the design process than current automotive techniques. The design of a complex safety-critical system will require many decisions that can potentially impact the system's safety. A safety analysis should be performed on the new design to understand any potential safety issues. Methods that can help identify where and how the change impacts the analysis would be a useful tool for designers and managers. This could reduce the amount of time needed to evaluate changes and to ensure the safety goals of the system are met. This thesis demonstrates managing design changes for the safetyƯ-guided design of an automotive safetyƯ-critical shift-by-wire system. The current safety related analysis methods and standards common to the automotive industry and the system engineering methods and research in the use of requirements traceability for impact analysis in engineering change management was reviewed. A procedure was proposed to identify the impact of design changes to the safety analysis performed with STPA. Suggested guidelines were proposed to identify the impact of the change on the safety analysis performed with STPA. It was shown how the impact of the design changes were incorporated into the STPA results to ensure safety constraints are managed with respect to these changes to maintain the safety controls of the system throughout the design process. Finally the feasibility of the procedure was demonstrated through the integration of the procedure with requirements traceability based on system engineering practices
by John Sgueglia.
S.M. in Engineering and Management

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7

Zhou, Jun. "Determination of Safety/Environmental Integrity Level for Subsea Safety Instrumented Systems." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for produksjons- og kvalitetsteknikk, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-23119.

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The master thesis describes, compares current methods in the literature, and proposes new methods for determination of safety/environmental integrity level of safety instrumented systems (SISs). These systems are used widely in many industry sectors to detect the onset of hazardous events and mitigate the consequences to humans, the environment and material assets. The main objective of this thesis has been to investigate the risk based approaches for determination of safety /environmental integrity level of SISs. The focus of the thesis is the risk graph and layer of protection analysis approach for subsea applications where the failure of such systems could lead to significant environmental consequences. The thesis builds on concepts, methods and definitions adopted in two main standards for SIS applications: IEC 61508 and IEC 61511. The proposals of new methods are inspired by these two standards and other relevant literature found during the master thesis project. The main contributions of this thesis are:1.Discussion on current environmental risk acceptance criteria used on Norwegian Continental Shelf and proposal of new environmental risk acceptance criteria based on release volume for subsea SISs applications where the consequences of hazardous events include environmental damages.2.A modified risk graph approach suited for SIL/EIL determinations for subsea SISs. This approach is demonstrated and tested in a case study.3.Detailed discussion on the effect of common cause failures between the designated SIS and the existing protection layers during SIL/EIL determination. A framework for determining SIL/EIL considering such CCFs is developed. This framework includes CCFs quantification in two phases: SIL determination phase and SIL realization phase. A checklist is developed for CCFs quantification in the early phase.

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Ojdanic, Milos. "SYSTEMATIC LITERATURE REVIEW OF SAFETY-RELATED CHALLENGES FOR AUTONOMOUS SYSTEMS IN SAFETY-CRITICAL APPLICATIONS." Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-43980.

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An increased focus on the development of autonomous safety-critical systems requiresmore attention at ensuring safety of humans and the environment. The mainobjective of this thesis is to explore the state of the art and to identify the safetyrelatedchallenges being addressed for using autonomy in safety-critical systems. Inparticular, the thesis explores the nature of these challenges, the different autonomylevels they address and the type of safety measures as proposed solutions. Above all,we focus on the safety measures by a degree of adaptiveness, time of being activeand their ability of decision making. Collection of this information is performedby conducting a Systematic Literature Review of publications from the past 9 years.The results showed an increase in publications addressing challenges related to theuse of autonomy in safety-critical systems. We managed to identify four high-levelclasses of safety challenges. The results also indicate that the focus of research wason finding solutions for challenges related to full autonomous systems as well assolutions that are independent of the level of autonomy. Furthermore, consideringthe amount of publications, results show that non-learning solutions addressing theidentified safety challenges prevail over learning ones, active over passive solutionsand decisive over supportive solutions.

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Ota, Shuichiro Daniel. "Assuring safety in high-speed magnetically levitated (maglev) systems : the need for a system safety approach." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45258.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2008.
Includes bibliographical references (p. 141-145).
Magnetic levitation is a railway technology that enables vehicles to be magnetically suspended above their tracks. Although this technology is still under development, magnetically levitated (maglev) systems have great potential to introduce significant changes in today's transportation networks. This thesis proposes an approach to assuring safety in high-speed maglev systems. It examines characteristic features of the systems, and analyzes the Japanese commuter railway accident in 2005, using Systems Theory Accident Modeling and Processes (STAMP) and System Dynamics models. The characteristic features reveal that the likelihood and potential severity of accidents in maglev systems are higher than those in conventional railway systems because of their high speed, levitation technology, software intensiveness, and other factors. A primary lesson learned from the accident is the importance of risk/hazard analysis that can qualitatively focus on the severity of accidents and human factors. These findings are put together in the form of requirements of risk/hazard analysis and organizational structures. This thesis demonstrates that these requirements, which are not entirely consistent with current actual practices based on international railway standards, conform well to the fundamentals of System Safety, which is an organized and established method to assure safety in complex systems.
by Shuichiro Daniel Ota.
S.M.

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10

Mahmoudi, Fashandi Ali R. "Stochastic analysis of robot-safety systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0026/NQ36781.pdf.

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11

Eriksson, Marcus. "Accelerator-driven systems : Safety and kinetics." Doctoral thesis, Stockholm : Department of Nuclear and reactor Physics, Royal Institute of Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-146.

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Jeppesen, B. P. "Enhancing safety in active suspension systems." Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.605592.

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Chapter 3 describes how a distributed control system architecture was designed, to fulfil the functional specification required of the vehicle. A safety review was performed on the conceptual design, which identified requirements for the control software and the need for an independent safe-shutdown system. The choice of hardware and a software development system for the co-ordinating Global Controller is described. The deign of the safe shutdown system is detailed. A multi-mode software structure is defined. Chapter 4 discusses the principles of fault detection, and their application in cases of ‘direct redundancy’. The logic required for voting systems, using identical sensors, is extended to the case of sensors whose measurements can be related instantaneously, for example using kinetics. Suitable sets of sensors on the experimental vehicle are identified, and test results are presented. Chapter 5 shows how fault detection can be made more precise by using dynamic models, rather than instantaneous relationships, to relate sensor measurements. The techniques are applied by dividing the experimental vehicle conceptually into subsystems. Identification of more subtle faults, including loss of suspension stiffness, is demonstrated.

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Bishnani, Zahir. "Safety criteria for aperiodic dynamical systems." Thesis, University of Warwick, 1997. http://wrap.warwick.ac.uk/57617/.

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The use of dynamical system models is commonplace in many areas of science and engineering. One is often interested in whether the attracting solutions in these models are robust to perturbations of the equations of motion. This question is extremely important in situations where it is undesirable to have a large response to perturbations for reasons of safety. An especially interesting case occurs when the perturbations are aperiodic and their exact form is unknown. Unfortunately, there is a lack of theory in the literature that deals with this situation. It would be extremely useful to have a practical technique that provides an upper bound on the size of the response for an arbitrary perturbation of given size. Estimates of this form would allow the simple determination of safety criteria that guarantee the response falls within some pre-specified safety limits. An excellent area of application for this technique would be engineering systems. Here one is frequently faced with the problem of obtaining safety criteria for systems that in operational use are subject to unknown, aperiodic perturbations. In this thesis I show that such safety criteria are easy to obtain by using the concept of persistence of hyperbolicity. This persistence result is well known in the theory of dynamical systems. The formulation I give is functional analytic in nature and this has the advantage that it is easy to generalise and is especially suited to the problem of unknown, aperiodic perturbations. The proof I give of the persistence theorem provides a technique for obtaining the safety estimates we want and the main part of this thesis is an investigation into how this can be practically done. The usefulness of the technique is illustrated through two example systems, both of which are forced oscillators. Firstly, I consider the case where the unforced oscillator has an asymptotically stable equilibrium. A good application of this is the problem of ship stability. The model is called the escape equation and has been argued to capture the relevant dynamics of a ship at sea. The problem is to find practical criteria that guarantee the ship does not capsize or go through large motions when there are external influences like wind and waves. I show how to provide good criteria which ensure a safe response when the external forcing is an arbitrary, bounded function of time. I also consider in some detail the phased-locked loop. This is a periodically forced oscillator which has an attracting periodic solution that is synchronised (or phase-locked) with the external forcing. It is interesting to consider the effect of small aperiodic variations in the external forcing. For hyperbolic solutions I show that the phase-locking persists and I give a method by which one can find an upperbound on the maximum size of the response.

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Birkinshaw, Carl Ian. "Engineering communicative distributed safety-critical systems." Thesis, University of Sheffield, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263801.

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May, John Hendy Robert. "Knowledge-based systems in engineering safety." Thesis, University of Bristol, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327937.

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Sajjad, Imran. "Autonomous Highway Systems Safety and Security." DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/5696.

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Automated vehicles are getting closer each day to large-scale deployment. It is expected that self-driving cars will be able to alleviate traffic congestion by safely operating at distances closer than human drivers are capable of and will overall improve traffic throughput. In these conditions, passenger safety and security is of utmost importance. When multiple autonomous cars follow each other on a highway, they will form what is known as a cyber-physical system. In a general setting, there are tools to assess the level of influence a possible attacker can have on such a system, which then describes the level of safety and security. An attacker might attempt to counter the benefits of automation by causing collisions and/or decreasing highway throughput. These strings (platoons) of automated vehicles will rely on control algorithms to maintain required distances from other cars and objects around them. The vehicle dynamics themselves and the controllers used will form the cyber-physical system and its response to an attacker can be assessed in the context of multiple interacting vehicles. While the vehicle dynamics play a pivotal role in the security of this system, the choice of controller can also be leveraged to enhance the safety of such a system. After knowledge of some attacker capabilities, adversarial-aware controllers can be designed to react to the presence of an attacker, adding an extra level of security. This work will attempt to address these issues in vehicular platooning. Firstly, a general analysis concerning the capabilities of possible attacks in terms of control system theory will be presented. Secondly, mitigation strategies to some of these attacks will be discussed. Finally, the results of an experimental validation of these mitigation strategies and their implications will be shown.

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Hawkins, Janine D. "Planning and implementing safety management systems." Thesis, Aston University, 2001. http://publications.aston.ac.uk/11768/.

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This thesis describes a study of the content and applicability of BS8800:1996 Guide to occupational health and safety management systems. The research is presented chronologically, with literature review and content analysis of SMS related guides and standards interwoven with two elements of qualitative empirical work. The first of these was carried out shortly after publication of BS8800 in 1996, a 'before-the-event' investigation of how organisations were intending to approach SMS implementation. The challenges faced by these organisations are reviewed against standard management theory, suggesting that the initial motivation for SMS implementation governs the approach organisations will adopt to guidance such as BS8800. The second phase of empirical work was undertaken in the context of OHSAS 18001, an auditable protocol based on BS8800, which allows organisations to certify their safety management systems. A discussion of the evolution of certifiable safety management system is presented, highlighting the similarities and differences between this, BS8800, SMS and wider management system standards. A case study then reviews the experiences of a catering company that implemented 18001, motivated by the opportunity for certification as a business benefit. The empirical work is used to comment on the guidance provided by BS8800, within its evolved role as guidance organisations may use for implementation of a SMS to be certified according to the specifications of OHSAS 18001. It is suggested that optimal implementation is facilitated by initial status review, continual improvement and the use of annexes, where there are used to make changes to the existing safety management system. This thesis concludes with a discussion of these elements, highlighting pertinent areas within BS8800 where revision or amendment may be appropriate.

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Fashandi, Ali R. M. "Stochastic analysis of robot-safety systems." Thesis, University of Ottawa (Canada), 1998. http://hdl.handle.net/10393/4112.

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Robot population is increasing at an incredible pace. Over the last fifteen years, robot population grew from 30,000 in 1983, to the forecasted 820,000 by the end of 1998. Their infancy period has come to an end and they are not just being used in the automotive industry or required to perform simple tasks. They are now being employed in various sectors of industry and handle much more complex operations. Increased robot system complexity and their critical applications utilization have led to various reliability and safety problems. In 1982, the Machine Tool Trade Associations guidelines stated that a working robot can be a potential hazard to personnel under certain circumstances. The need for robot system safety was highlighted by a 10-million dollar lawsuit awarded to the family of a worker killed by an industrial robot in 1983. This study presents a detailed introductory aspect of robot safety, an identification of the most appropriate robot systems reliability and safety assessment techniques, and probabilistic modelling of robot-safety systems. The domain of the probabilistic models include: a stochastic analysis of a system containing one robot with n-redundant safety units, a stochastic analysis of a system composed of n-redundant robots with one safety unit, and an availability analysis of robot systems susceptible to common-cause failure. The primal intent of the analyses is to develop generalized and numerical expressions relating to the performance indices for robot systems operating with or without the safety unit. Generalized models are introduced and generalized expressions including reliability, time-dependent availability, steady-state availability, and mean time to failure (MTTF) are developed. In order to assess performance indices, some special cases of the generalized models are presented resulting in the formation of numerical values. Robot system performance indices are determined by means of the Markovian and non-Markovian methods. The method of supplementary variables and the device of stages are used to deal with the non-Markovian models. Various failed system repair time distributions (i.e., exponential, gamma, Weibull, Rayleigh, and log-normal distributions) have been considered to obtain generalized steady state availability expressions. Markov method is utilized in models where failure and repair rates are assumed constant. With the aid of Laplace transforms, a system of first-order differential equations are solved and generalized reliability and MTTF expressions are developed.

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Aslansefat, K., Sohag Kabir, Amr R. A. Abdullatif, Vinod Vasudevan, and Y. Papadopoulos. "Toward Improving Confidence in Autonomous Vehicle Software: A Study on Traffic Sign Recognition Systems." IEEE, 2021. http://hdl.handle.net/10454/18591.

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Yes
This article proposes an approach named SafeML II, which applies empirical cumulative distribution function-based statistical distance measures in a designed human-in-the loop procedure to ensure the safety of machine learning-based classifiers in autonomous vehicle software. The application of artificial intelligence (AI) and data-driven decision-making systems in autonomous vehicles is growing rapidly. As autonomous vehicles operate in dynamic environments, the risk that they can face an unknown observation is relatively high due to insufficient training data, distributional shift, or cyber-security attack. Thus, AI-based algorithms should make dependable decisions to improve their interpretation of the environment, lower the risk of autonomous driving, and avoid catastrophic accidents. This paper proposes an approach named SafeML II, which applies empirical cumulative distribution function (ECDF)-based statistical distance measures in a designed human-in-the-loop procedure to ensure the safety of machine learning-based classifiers in autonomous vehicle software. The approach is model-agnostic and it can cover various machine learning and deep learning classifiers. The German Traffic Sign Recognition Benchmark (GTSRB) is used to illustrate the capabilities of the proposed approach.
This work was supported by the Secure and Safe MultiRobot Systems (SESAME) H2020 Project under Grant Agreement 101017258.

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Hawkins, Richard D. "Using safety contracts in the development of safety critical object-oriented systems." Thesis, University of York, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437585.

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Hilario, Grace. "Patient Safety Problems, Procedures, and Systems Associated with Safety Reporting and Turnover." ScholarWorks, 2019. https://scholarworks.waldenu.edu/dissertations/7103.

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Research has shown that 400,000 people die every year due to preventable medical errors. Medical error reporting and safety is a responsibility of all members of a health care organization. Creating an environment that addresses and prevents potential or actual safety problems can help reduce the incidence of medical errors made by nurses in the workplace. The purpose of this quantitative research study was to determine if nurses' perceptions of safety problems and error-preventing procedures and systems affected their comfort in reporting safety problems and intent to leave. High-reliability theory was the theoretical foundation for this study. Data were obtained from 1,171 surveys completed by newly licensed registered nurses located in 51 different metropolitan statistical areas and 9 counties. SPSS Version 25 was used to conduct a secondary data analysis including descriptive statistics, bivariate analysis, and multiple logistic regression for each variable. Themes that emerged from the data analysis included the importance of education on safety protocols and improving nurse satisfaction and nurse retention. The findings of the study might contribute to social change by creating an increased awareness for nurse leaders, managers, and newly licensed registered nurses in ensuring that there is improved comfort of reporting and appropriate error-preventing procedures and system in the health care environment. Increased awareness will allow for action and improved protocols to enhance the overall safety and quality of care for nurses and their patients.

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Tong, Choon Yin. "Architecting the safety assessment of large-scale systems integration." Monterey, California : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/theses/2009/Dec/09Dec%5FTong.pdf.

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Thesis (M.S. in Systems Engineering and Analysis)--Naval Postgraduate School, December 2009.
Thesis Advisor(s): Paulo, Eugene. Second Reader: Rhoades, Mark. "December 2009." Description based on title screen as viewed on January 27, 2010. Author(s) subject terms: Systems integration, System safety, System-of-Systems safety. Includes bibliographical references (p. 51-52). Also available in print.

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Jaradat, Omar Tawffeeq Saleem. "Automated Architecture-Based Verification of Safety-Critical Systems." Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-25207.

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Safety-critical systems require high quality and dependability levels, where system correctness and safety are major features to avoid any severe outcome. Time and cost are also important challenges that are imposed during the development process. Describing the behavior of a system in a high level provides a realistic vision and anticipation of the system. This presents a valuable opportunity for verifying the system before wasting the intended resources to develop the system. Architecture Description Languages (ADLs) provide the ability to comprise and represent the system level details of components, interactions and configuration. Architecture Analysis and Design Language (AADL) as a family member of ADLs proved its effectiveness in designing software intensive systems. In this report, we present a case study to validate “An Architecture-Based Verification Technique for AADL Specifications”. The technique involves a combination of model checking and model-based testing approaches adapted to an architectural perspective. The objectives of the verification process are 1) to ensure completeness and consistency of an AADL specification, and 2) to ensure conformance of an implementation with respect to its AADL specification. The technique has only been applied to small examples, and the goal of this thesis work is to validate it against a safety-critical system developed by a major vehicle manufacturer. Validation of the technique begins by investigating the system and specifying it in AADL. The defined verification criteria are subsequently applied to the AADL specification which drives the verification process. The case study presents interesting results while performing the model checking (the completeness and consistency checking). Conformance testing, on the other hand, could not be performed on the implemented system but is an interesting topic for future work.

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Newbury, Brian. "Integrated health, safety and environmental management systems." Thesis, University of South Wales, 2000. https://pure.southwales.ac.uk/en/studentthesis/integrated-health-safety-and-environmental-management-systems(6a947bb5-bda0-4466-9cb6-f02ad514cb9a).html.

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The continued rise in accident and ill health statistics throughout the member states of the European Union indicate that the standards of occupational health, safety and environmental control require further improvement to minimise the current level of loss. Management systems are regarded as an effective means of reducing this loss by continuously improving standards. Whilst there is much discussion and debate about the possibilities of integrating management systems, at present, there are no national or international published integrated management standards, although some multi-national companies have introduced their own internal integrated standards. The research explored the development of an integrated health, safety and environmental (HSE) management system within a range of industrial organisations. This included the development of tools for successful implementation of integrated systems, specifically for significance review, risk assessment and auditing. Resources and accreditation constraints precluded exhaustive testing of all clauses within the proposed integrated management standard. However, analysis of key aspects of the standard revealed: 1. The introduction and use of separate health, safety and environmental (HSE) management systems improved the standards of risk control within organisations. 2. Organisations perceived that there were clear business advantages in some form of integration of existing standards. 3. The developed integrated HSE standard was technically possible in the area of policy development, process operations, working instructions and documentation. However, the integration of risk assessment and audit tools gave limited advantages compared to existing separate systems. 4. The proposed integrated HSE standard complied with both individual European member states national legislative requirements and European/World-wide management standard criteria. In summary this thesis represents an original contribution to the field of integrated management systems. The thesis also identifies areas of further work that will increase the knowledge base, scope of application of the work carried out.

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Kvam, Eva. "Effect of Safe Failures on the Reliability of Safety Instrumented Systems." Thesis, Norwegian University of Science and Technology, Department of Mathematical Sciences, 2008. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9809.

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Safety instrumented systems (SISs) are of prime importance to the process industry to avoid catastrophic consequences or even loss of human life. The dangerous situations that any equipment may face should be analysed in order to quantify the associated risk and to choose a design of the SIS that reduces the risk to a tolerable level. The safe failure fraction (SFF) is a parameter defined in the standards IEC 61508 and IEC 61511, and is used to determine the need for additional channels that can activate the safety function if a failure is present. The standards consider a high SFF as an indicator of a safe design, and by increasing SFF, one may allow a lower redundancy level for a SIS and therefore reduce costs. Safety engineers discuss the suitability of this parameter, and some argue that the negative effects of safe failures on the reliability are so significant that the parameter should not be used. For a safety shutdown valve installed to prevent overpressure, a safe failure is defined as a spurious closure where the source of high pressure is isolated. This thesis examines the effects of safe failures on the reliability of such systems by using a Markov model. According to IEC 61508 and IEC 61511 the system reliability of a safety shutdown system is measured by the probability of failure on demand (PFD). From the results it can be concluded that the time needed to restore the system back to initial state after a safe failure does not have a significant effect on PFD. A long restoration time after a safe failure in combination with a high frequency of safe failures is negative with respect to production downtime. The main contributor to PFD is the long run probability of being in a state where a dangerous undetected (DU) failure is present. DU failures are normally detected by function tests or sometimes upon demand, but they can also be revealed by a spurious closure. This effect is based on the assumption of perfect repair of safe failures, which means that all possible failure modes are detected and the failed items are repaired or replaced after restoration of safe failures. The ability to reveal DU failures is clearly dependent on the frequency of a DU failure and safe failure occurring in the same test interval. This thesis demonstrates that safe failures only have significant effect when the dangerous failure rate is high. Other parameters affect the PFD to a greater extent, and the importance of exact parameter estimation is crucial and more important than the positive effects of safe failures. The SFF must be close to 100% to have a significant effect on the PFD, and since it is always aimed at minimising the number of dangerous failures, the alternative is to add safe failures. This is probably not the intent of SFF and is negative with respect to production downtime. Safe failures does not justify a lower degree of redundancy. On the other hand, the positive effects of safe failures show a satisfactory reason for adopting a longer test interval. This is an optimisation of PFD and can reduce costs or even the frequency of dangerous situations during start-up and shutdown. This thesis demonstrates that the PFD is not affected by safe failures, and indicates no reason to be in doubt about this parameter as a measure of reliability. The SFF gives hardly any information and the choice of SIS architecture should not be based on SFF alone. An alternative parameter that considers different means of revealing DU failures seems to be a better choice.

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Warren, Bradley R. "A framework for software reuse in safety-critical system of systems." Thesis, Monterey, Calif. : Naval Postgraduate School, 2008. http://bosun.nps.edu/uhtbin/hyperion-image.exe/08Mar%5FWarren.pdf.

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Thesis (M.S. in Software Engineering)--Naval Postgraduate School, March 2008.
Thesis Advisor(s): Michael, James B. ; Shing, Mantak. "March 2008." Description based on title screen as viewed on May 16, 2008. Includes bibliographical references (p. 77-79). Also available in print.

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Salewski, Falk. "Empirical evaluations of safety-critical embedded systems." Aachen RWTH, Fachgruppe Informatik, 2008. http://d-nb.info/1000120724/34.

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Rao, Shrisha. "Safety and hazard analysis in concurrent systems." Diss., University of Iowa, 2005. http://ir.uiowa.edu/etd/106.

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Peters, Alan J. "The safety of personal rapid transit systems." Thesis, University of Bristol, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539778.

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Kane, Aaron. "Runtime Monitoring for Safety-Critical Embedded Systems." Research Showcase @ CMU, 2015. http://repository.cmu.edu/dissertations/532.

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The trend towards more commercial-off-the-shelf (COTS) components in complex safety-critical systems is increasing the difficulty of verifying system correctness. Runtime verification (RV) is a lightweight technique to verify that certain properties hold over execution traces. RV is usually implemented as runtime monitors that can be used as runtime fault detectors or test oracles to analyze a system under test for bad behaviors. Most existing RV methods utilize some form of system or code instrumentation and thus are not designed to monitor potentially black-box COTS components. This thesis presents a suitable runtime monitoring framework for monitoring safety-critical embedded systems with black-box components. We provide an end-to-end framework including proven correct monitoring algorithms, a formal specification language with semi-formal techniques to map the system onto our formal system trace model, specification design patterns to aid translating informal specifications into the formal specification language, and a safety-case pattern example showing the argument that our monitor design can be safely integrated with a target system. We utilized our monitor implementation to check test logs from several system tests. We show the monitor being used to check system test logs offline for interesting properties. We also performed real-time replay of logs from a system network bus, demonstrating the feasibility of our embedded monitor implementation in real-time operation.

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Ödman, Torbjörn. "Wireless measurement systems for health and safety." Licentiate thesis, Mälardalens högskola, Inbyggda system, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-28765.

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This licentiate thesis presents an advanced wireless system, built on a single hardware platform, for applications in medicine and health. In order to design a single system, adaptable for different context, an accurate system specification is required. The technical requirements are authenticated by actual tests in the environment where the system is intended to be used. The results of these measurements give an understanding of the possibilities of designing a real system but also acts as a base for deriving the empirical formulas to be used as the basis of the development and verification. In summary, this work has included a larger measurement campaign and a verification of subsystems to support the development of wireless systems on a single hardware platform. This can be used for different measurements in medical healthcare and rescue work. Previous systems for endurance tests have limitations in that they are not adapted to different sizes of mammals and they also have shortcomings in the quantification of data and scalability. The developed system was validated on mice and humans. On mice the measurement parameters was the hormone dopamine and locomotion. For humans it was measured time for given distances. Both validation tests showed high correlation with the respective reference methods. The correlation coefficients of mice between the developed system and the former system ranged from 0.916 to 0.967. In the validation with humans, runners were clocked by the system clock and a manual stop watch. The lowest correlation coefficient was 0.864. Advantages with the developed system is that it is scalable and measures the activity level quantitatively in the unit meters and it can also be used for different sizes of mammals in different environments. In tracking devices for rescue it is important that the transmitted signal can be detected at distances as large as possible. A support in the design work is to simulate path loss. This requires a path loss exponent, which was calculated after the measurement campaign. The results showed that the exponent of the height dependency decreases with antenna height above water. For the frequency 200 MHz, the exponent for the antenna height is 0.4 (vertical polarization) and 1.5 (horizontal polarization). For the distance dependency, the exponent was 3.59 (vertical polarization) and 3.22 (horizontal polarization). The path loss exponent is 2 for both the free space- and the ground reflection model. An antenna’s physical dimension is to a large extent dependent on the lowest frequency. The research’s aim was to reduce the physical size by introducing a resonance frequency. The physical length was from the beginning 0.43 meter given by the lowest frequency used (0.7 GHz) and the antenna was reduced in size to 0.22 meter.

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Marriott, Derek Garron. "Analysis of safety-critical parallel software systems." Thesis, University of Sheffield, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388710.

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Akladios, Magdy. "Safety by design-- an expert systems approach /." Morgantown, W. Va. : [West Virginia University Libraries], 1999. http://etd.wvu.edu/templates/showETD.cfm?recnum=1033.

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Thesis (Ph. D.)--West Virginia University, 1999.
Title from document title page. Document formatted into pages; contains xi, 238 p. : ill. (some col.) Includes abstract. Includes bibliographical references (p. 231-238).

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Livadas, Carolos. "Formal verification of safety-critical hybrid systems." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/42817.

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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1997.
Includes bibliographical references (p. 181-185).
This thesis investigates how the formal modeling and verification techniques of computer science can be used for the analysis of hybrid systems [7,14,22,37] - systems involving both discrete and continuous behavior. The motivation behind such research lies in the inherent similarity of the hierarchical and decentralized control strategies of hybrid systems and the communication and operation protocols used for distributed systems in computer science. As a case study, the thesis focuses on the development of techniques that use hybrid I/O automata [29,30] to model and analyze automated vehicle transportation systems and, in particular, their various protection subsystems - control systems that are used to ensure that the physical plant at hand does not violate its various safety requirements. The thesis is split into two major parts. In the first part, we develop an abstract model of a physical plant and its various protection subsystems - also referred to as protectors. The specialization of this abstract model results in the specification of a particular automated transportation system. Moreover, the proof of correctness of the abstract model leads to simple correctness proofs of the protector implementations for particular specializations of the abstract model. In this framework, the composition of independent protectors is straightforward - their composition guarantees the conjunction of the safety properties guaranteed by the individual protectors. In fact, it is shown that under certain conditions composition holds for dependent protectors also. In the second part, we specialize the aforementioned abstract model to simplified versions of the personal rapid transit system (PRT 200TM) under development at Raytheon Corporation. We examine overspeed and collision protection for a set of vehicles traveling on straight tracks, on binary merges, and on a directed graph of tracks involving binary merges and diverges. In each case, the protectors sample the state of the physical plant and take protective actions to guarantee that the physical plant does not reach hazardous states. The proofs of correctness of such protectors involve specializing the abstract protector to the physical plant at hand and proving that the suggested protector implementations are correct. This is done by defining simulations among the states of the protector implementations and their abstract counterparts.
by Carolos Livadas.
M.Eng.

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Johnson, Kip E. (Kip Edward) 1978. "Systems-theoretic safety analyses extended for coordination." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/108922.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2017.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 191-199).
When interdependent conditions exist among decision units, safety results in part from coordination. Safety analysis methods should correspondingly address coordination. However, state-of-the-art safety analysis methods have limited guidance for analytical inquiry into coordination between interdependent decision systems. This thesis presents theoretical and applied research to address the knowledge gap by extending STAMP (Systems-Theoretic Accident Model and Processes)-based analysis methods STPA (System-Theoretic Process Analysis) and CAST (Causal Analysis based on STAMP). This thesis contributes to knowledge by introducing: 1) a coordination framework for use in analysis, 2) STPA-Coordination and CAST-Coordination, which extend STPA and CAST to analyze coordination, and 3) flawed coordination analysis guidance for use in the extensions. The coordination framework provides explanatory power for observation of and analysis of coordination in sociotechnical systems. The coordination framework includes perspectives for use in the evaluation of coordination, which are used to operationalize the framework for analysis. STPA-Coordination extends STPA with additional steps for analysis of how coordination can lead to unsafe controls (i.e. hazards). In part, STPA-Coordination uses analysis guidance introduced in this thesis that consists of four unique flawed coordination cases and nine coordination elements. CAST-Coordination extends CAST with additional steps to investigate accident causation influences from flawed coordination. Two case studies evaluate the utility of extensions, flawed coordination guidance, and the framework. One case study investigates the application of STPA-Coordination to a current and significant sociotechnical system challenge-unmanned aircraft systems integration into military and civil flight operations. Results are compared to official functional hazard analysis and requirements results. The comparison shows that STPA-Coordination provides additional insights into identifying hazardous coordination scenarios and recommendations. Another case study applies CAST-Coordination to investigate a Patriot missile friendly fire (2003) during Operation Iraqi Freedom, which is a relevant concern today. CAST-Coordination is successfully applied to the friendly-fire coordination problem. When compared to official government accident investigation reports, CAST-Coordination shows benefits in identifying accident influences and generating recommendations to address the coordination and safety problem. Both case study quantitative and qualitative results are promising and suggest STPA- and CAST-Coordination and the coordination framework are useful.
by Kip Edward Johnson.
Ph. D.

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Al-Humam, Abdulaziz. "Service-oriented architectures for safety-critical systems." Thesis, University of York, 2015. http://etheses.whiterose.ac.uk/11823/.

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Many organisations in the safety-critical domain are service-oriented, fundamentally centred on critical services provided by systems and operators. Increasingly, these services rely on software-intensive systems, e.g. medical health informatics and air traffic control, for improving the different aspects of industrial practice, e.g. enhancing efficiency through automation and safety through smart alarm systems. However, many services are categorised as high risk and as such it is vital to analyse the ways in which the software-based systems can contribute to unintentional harm and potentially compromise safety. This thesis defines an approach to modelling and analysing Service-Oriented Architectures (SOAs) used in the safety-critical domain, with emphasis on identifying and classifying potential hazardous behaviour. The approach also provides a systematic and reusable basis for defining how the safety case for these SOAs can be developed in a modular manner. The approach is tool-supported and is evaluated through two case studies, from the healthcare and oil and gas domains, and industrial review.

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Black, Derrick Davidson. "Management of safety - a systems engineering approach." Thesis, Ulster University, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.490744.

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In delivering Safety in systems it is not only essential to ensure that each part of the system is safe but that account is taken of the interrelationship between the components of the system and the relationship with its environment. When viewed from a System Engineering perspective safety is often "pigeon-holed" into non-functional aspects, while, when viewed from the standpoint of Engineering Management it is considered in terms of organisational culture. In reality, both views must be considered.

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Cheng, Shen. "Stochastic analysis of standby robot-safety systems." Thesis, University of Ottawa (Canada), 2007. http://hdl.handle.net/10393/27820.

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Nowadays, the application of robots covers almost all aspects of our daily life. They are used to perform increasing complex and critical operations. The increased critical applications have led to various reliability and safety problems, especially many people are injured and killed every year. This study presents reliability and availability analyses of six different standby robot-safety systems: one robot and (n-1) standby safety units with a perfect switch, one robot and (n-1) standby safety units with an imperfect switch, (n-1) standby robots and one safety unit with a perfect switch, (n-1) standby robots and one safety unit with an imperfect switch, n parallel robots and (m-1) standby unit with a perfect switch, and two parallel robots and one standby unit with an imperfect switch. With the aid of Markov and supplementary variable methods, general expressions for system state probabilities, system availability, reliability and mean time to failure were obtained. Plots of some of these expressions are shown to demonstrate the effect of varying failure rates or repair rates of the safety unit, and other parameters.

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Bayton, David Andrew. "Optimised connection systems in dynamic safety barriers." Thesis, Swansea University, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.556577.

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Simpson, Andrew C. "Safety through security." Thesis, University of Oxford, 1996. http://ora.ox.ac.uk/objects/uuid:4a690347-46af-42a4-91fe-170e492a9dd1.

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In this thesis, we investigate the applicability of the process algebraic formal method Communicating Sequential Processes (CSP) [Hoa85] to the development and analysis of safetycritical systems. We also investigate how these tasks might be aided by mechanical verification, which is provided in the form of the proof tool Failures-Divergences Refinement (FDR) [Ros94]. Initially, we build upon the work of [RWW94, Ros95], in which CSP treatments of the security property of non-interference are described. We use one such formulation to define a property called protection, which unifies our views of safety and security. As well as applying protection to the analysis of safety-critical systems, we develop a proof system for this property, which in conjunction with the opportunity for automated analysis provided by FDR, enables us to apply the approach to problems of a sizable complexity. We then describe how FDR can be applied to the analysis of mutual exclusion, which is a specific form of non-interference. We investigate a number of well-known solutions to the problem, and illustrate how such mutual exclusion algorithms can be interpreted as CSP processes and verified with FDR. Furthermore, we develop a means of verifying the faulttolerance of such algorithms in terms of protection. In turn, mutual exclusion is used to describe safety properties of geographic data associated with Solid State Interlocking (SSI) railway signalling systems. We show how FDR can be used to describe these properties and model interlocking databases. The CSP approach to compositionality allows us to decompose such models, thus reducing the complexity of analysing safety invariants of SSI geographic data. As such, we describe how the mechanical verification of Solid State Interlocking geographic data, which was previously considered to be an intractable problem for the current generation of mechanical verification tools, is computationally feasible using FDR. Thus, the goals of this thesis are twofold. The first goal is to establish a formal encapsulation of a theory of safety-critical systems based upon the relationship which exists between safety and security. The second goal is to establish that CSP, together with FDR, can be applied to the modelling of Solid State Interlocking geographic databases. Furthermore, we shall attempt to demonstrate that such modelling can scale up to large-scale systems.

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Ljosland, Ingvar. "BUCS: Patterns and Robustness : Experimentation with Safety Patterns in Safety-Critical Software Systems." Thesis, Norwegian University of Science and Technology, Department of Computer and Information Science, 2006. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-10088.

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In modern society, we rely on safely working software systems. This is the final report in a masters degree project to reveal key issues in the science field of computer software architecture and design of safety-critical software systems. A pre-study of a navigation system implied that functionality related problems and safety-critical problems do not stack one to one, but rather is a case of solving these aspects in different layers. This means that changes in software systems functionality do not necessary mean that change in safety-critical modules has to be done as well, and visa versa. To further support the findings in the pre-study, an experiment was created to investigate these matters. A group of twenty-three computer science students from the Norwegian University of Science and Technology (NTNU) participated as subjects in the experiment. They were asked to make two functional additions and two safety-critical additions to a software robot emulator. A dynamic web tool was created to present information to the subjects, and they could here answer surveys and upload their task solutions. The results of the experiment shows that there were not found any evidence that the quality attributes got affected by the design approaches. This means that the findings of this study suggest that there is difficult to create safety-critical versions of software architectural design patterns, because all design patterns have a set of additions and concequences to a system, and all sides of the implications of the design pattern should be discussed by the system architects before used in a safety-critical system.

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Chan, Kenneth H. W. "The application of formal methods in safety analysis for safety critical software systems." Thesis, Teesside University, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.411289.

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Kuusisto, Arto. "Safety management systems : audit tools and reliability of auditing /." Espoo [Finland] : Technical Research Centre of Finland, 2000. http://www.vtt.fi/inf/pdf/publications/2000/P428.pdf.

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Owarish, Miles I. "Concepts of integration of fire safety systems with building services systems." Thesis, Heriot-Watt University, 2000. http://hdl.handle.net/10399/523.

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45

Mahsoon, Alaa. "The Relationships Among Systems Thinking, Safety Culture, Safety Competency and Safety Performance of Registered Nurses in Saudi Arabia." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1565193017213961.

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46

Canham, Aneurin. "Examining the application of STAMP in the analysis of patient safety incidents." Thesis, Loughborough University, 2018. https://dspace.lboro.ac.uk/2134/36150.

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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.

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Pattison, Rachel Lesley. "Safety system design optimisation." Thesis, Loughborough University, 2000. https://dspace.lboro.ac.uk/2134/22019.

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This thesis investigates the efficiency of a design optimisation scheme that is appropriate for systems which require a high likelihood of functioning on demand. Traditional approaches to the design of safety critical systems follow the preliminary design, analysis, appraisal and redesign stages until what is regarded as an acceptable design is achieved. For safety systems whose failure could result in loss of life it is imperative that the best use of the available resources is made and a system which is optimal, not just adequate, is produced. The object of the design optimisation problem is to minimise system unavailability through manipulation of the design variables, such that limitations placed on them by constraints are not violated. Commonly, with mathematical optimisation problem; there will be an explicit objective function which defines how the characteristic to be minimised is related to the variables. As regards the safety system problem, an explicit objective function cannot be formulated, and as such, system performance is assessed using the fault tree method. By the use of house events a single fault tree is constructed to represent the failure causes of each potential design to overcome the time consuming task of constructing a fault tree for each design investigated during the optimisation procedure. Once the fault tree has been constructed for the design in question it is converted to a BDD for analysis. A genetic algorithm is first employed to perform the system optimisation, where the practicality of this approach is demonstrated initially through application to a High-Integrity Protection System (HIPS) and subsequently a more complex Firewater Deluge System (FDS). An alternative optimisation scheme achieves the final design specification by solving a sequence of optimisation problems. Each of these problems are defined by assuming some form of the objective function and specifying a sub-region of the design space over which this function will be representative of the system unavailability. The thesis concludes with attention to various optimisation techniques, which possess features able to address difficulties in the optimisation of safety critical systems. Specifically, consideration is given to the use of a statistically designed experiment and a logical search approach.

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Horney, David Craig. "Systems-theoretic process analysis and safety-guided design of military systems." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/112424.

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Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2017.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 95-97).
Increasingly complex software enabled systems demand a new hazard analysis and safety-guided design technique in order to meet stringent safety standards and expectations. System Theoretic Process Analysis (STPA) proves to be a powerful tool to identify, describe and help mitigate hazards from the earliest conceptual development through the operations of a system. A future military aircraft example demonstrates STPA's applicability for preliminary hazard analysis, analysis of alternatives, organizational design, developmental test, and into operations. STPA is a hazard analysis framework that helps manage risks and safety responsibilities throughout the entire lifecycle of a system.
by David Craig Horney.
S.M.

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Yu, Yin. "Analysis of structural vulnerability." Thesis, University of Bristol, 1997. http://hdl.handle.net/1983/7d8392ee-c2b6-4bf1-97d5-c3178bd93d45.

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Dong, Airong S. M. Massachusetts Institute of Technology. "Application of CAST and STPA to railroad safety in China." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/76491.

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Thesis (S.M. in Engineering and Management)--Massachusetts Institute of Technology, Engineering Systems Division, System Design and Management Program, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 83-84).
The accident analysis method called STAMP (System-Theoretic Accident Model), developed by Prof. Nancy Leveson from MIT, was used here to re-analyze a High Speed Train accident in China. On July 23rd, 2011, 40 people were killed and 120 injured on the Yong-Wen High Speed Line. The purpose of this new analysis was to apply the broader view suggested by STAMP, considering the whole socio-technological system and not only equipment failures and operators mistakes, in order to come up with new findings, conclusions and recommendations for the High Speed Train System in China. The STAMP analysis revealed that the existing safety culture in the whole train organization, the Ministry of Railway and all its sub organizations in both the Train Development and Train Operation channels, do not meet the safety challenges involved in a high risk system like this- running frequent trains on the same line at 250km/h, with hundreds of passenger on board. The safety hazards were not systematically analyzed (not at the top level nor at the design level), safety constraints and safety requirements were very vaguely phrased, and no real enforcement was applied on safe design and implementation nor on safe operation. It looks like no clear policy on the performance/safety dilemma existed, nor the necessary safety education and training. Following from the STAMP analysis, one of the major recommendations in this thesis is to create a professional Train Safety Authority at the highest level, to be in charge of creating and supervising the rules for both Engineering and Operations, those two being highly interrelated with respect to safety. Specific Control Structures are recommended too, along with some detailed technical recommendations regarding the fail-safe design of the equipment involved in the accident. Another major recommendation is to design the safety critical systems, like the signaling control system using STPA ((System Theoretic Process Analysis), a hazard analysis technique. In the second part of this thesis, STPA is applied to another signaling system-Communication Based Train Control (CBTC) system-which is similar to the one presented in the first part. The primary goal of STPA is to include the new causal factors identified in STAMP that are not handled by the older techniques. It aims to identify accident scenarios that encompass the entire accident process, including design errors, social, organizational, and management factors contributing to accidents. These are demonstrated in the STPA analysis section.
by Airong Dong.
S.M.in Engineering and Management

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Dissertations / Theses on the topic 'SAFETY SYSTEMS'

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