Dissertations / Theses on the topic 'Risk-Informed Decision Making'

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2010.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 104-107).
Risk-informed decision-making (RIDM) is a formal process that assists stakeholders make decisions in the face of uncertainty. At MIT, a tool known as the Analytic Deliberative Decision Making Process (ADP) has been under development for a number of years to provide an efficient framework for implementing RIDM. ADP was initially developed as a tool to be used by a small group of stakeholders but now it has become desirable to extend ADP to an engineering scale that can be used by many individual across large organizations. This dissertation identifies and addresses four challenges in extended the ADP to an engineering scale. Rigorous preference elicitation using pairwise comparisons is addressed. A new method for judging numerical scales used in these comparisons is presented along with a new type of scale. This theory is tested by an experiment involving 64 individuals and it is found that the optimal scale is a matter of individual choice. The elicitation of expert opinion is studied and a process that adapts to the complexity of the decision at hand is proposed. This method is tested with a case study involving the choice of a heat removal technology for a new type of fission reactor. Issues related to the unique informational needs of large organizations are investigated and new tools to handle these needs are developed. Finally, difficulties with computationally intensive modeling and simulation are identified and a new method of uncertainty propagation using orthogonal polynomials is explored. Using a code designed to investigate the LOCA behavior of a fission reactor, it is demonstrated that this new propagation methods offers superior convergence over existing techniques.
by Michael A. Elliott.
Ph.D.

Thesis (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2005.
Includes bibliographical references (p. 66-68).
Model uncertainties can have a significant impact on decisions regarding licensing basis changes. We present a methodology to identify basic events in the risk assessment that have the potential to change the decision and are known to have significant model uncertainties. Because we work with basic event probabilities, this methodology is not appropriate for analyzing uncertainties that cause a structural change to the model, such as success criteria. We use the Risk Achievement Worth (RAW) importance measure with respect to both the core damage frequency (CDF) and the change in core damage frequency (ACDF) to identify potentially important basic events. We cross-check these with generically important model uncertainties. Then, sensitivity analysis is performed on the basic event probabilities, which are used as a proxy for the model parameters, to determine how much error in these probabilities would need to be present in order to impact the decision. A previously submitted licensing basis change is used as a case study. Analysis using the SAPHIRE program identifies 20 basic events as important, four of which have model uncertainties that have been identified in the literature as generally important.
(cont.) The decision is fairly insensitive to uncertainties in these basic events. In three of these cases, one would need to show that model uncertainties would lead to basic event probabilities that would be between two and four orders of magnitude larger than modeled in the risk assessment before they would become important to the decision. More detailed analysis would be required to determine whether these higher probabilities are reasonable. Methods to perform this analysis from the literature are reviewed and an example is demonstrated using the case study. We then look at policy issues surrounding the effects of uncertainty in decision making related to nuclear power generation.
by Joshua M. Reinert.
S.M.

Risk mitigation decisions for civil infrastructure exposed to rare natural and manmade hazards are often impacted by risk aversion, a behavioral phenomenon in which the decision maker's perception and judgment of risk are systematically distorted, resulting in decisions that might be viewed as excessively conservative when compared to those from a traditional minimum expected cost analysis. This study addresses how decisions regarding structural safety are affected by the attitudes of the decision-maker toward risk using decision models, such as cumulative prospect theory, that allow risk-averse behaviors to be modeled quantitatively. Perspectives on the general characteristics of risk-aversion are first drawn from risk pricing techniques in the insurance industry. These perspectives are then refined for structural engineering applications by investigations of decisions involving seismic retrofit of unreinforced masonry structures in San Francisco, CA and aseismic design of a steel moment frame in Vancouver, BC. Risk attitudes when confronting extreme wind hazards are also assessed using a decision by the North and South Carolina Code Councils to waive a provision in the International Residential Code that would have required additional windborne debris protection in residential construction. An examination of risk attitudes toward competing natural hazards is then introduced by comparing decisions related to wind and seismic effects in areas where both hazards may be significant. These investigations have led to tentative conclusions regarding the role of risk aversion in the assurance of structural safety and in code-related decisions and suggest avenues for future study.

Flood risk reduction is a global challenge. Society demands higher safety and security levels, including those actions related to flood defence infrastructure protection against natural hazards and manmade threats. Dams and levees, among other flood defence infrastructures, are critical hydraulic infrastructures, aiming at reducing the likelihood that people and property will get flooded, but whose failure would result in consequences for the community downstream, including not only economic damages but also loss of life. There is always a probability associated with infrastructure failure, although in general it might be very low. The purpose of the PhD research, with title "Integrated flood risk management: towards a risk-informed decision making incorporating natural and human-induced hazards", here presented is to propose a framework to enhance integrative flood risk management from a multi-hazard perspective (pluvial flooding, river flooding, dam and levee failure, including man-made threats), addressing current needs for decision making on flood risk reduction and analyzing the complexity of multiple hazards and systems which include multiple components. The thesis is structured in three main parts, including: (i) Part I, a methodology aiming at providing a common framework for identifying and characterizing flood risk due to pluvial flooding, river flooding and dam failure, and incorporate information on loads, system response and consequences into risk models to analyse societal and economic flood risk, (ii) Part II, an approach for quantifying and analyzing risk for complex dam-levee systems, to incorporate information from levee failure into risk models based on the aforementioned methodology, and to analyse societal and economic flood risk, including the potential failure of these infrastructures, and (iii) Part III, a screening tool to characterize the impact of human induced threats on risk due to dam failure or mission disruption. Results from this research have proven that the use of risk models provides a logic and mathematically rigorous framework for compiling information for flood risk characterization and analysis from different natural hazards and flood defence performance. The proposed framework in this thesis and applications aimed at encouraging key actors on flood risk management (infrastructure managers, authorities, emergency action planners, etc.) on the use of QRA, and at demonstrating to what extent QRA can usefully contribute to better understanding risk drivers and inform decisions on how to act to efficiently reduce flood risk.
La reducción del riesgo de inundación es un reto global. La sociedad actual demanda cada vez mayores niveles de seguridad, incluyendo la consecución de acciones vinculadas a la protección de las infraestructuras de defensa frente a inundaciones ante amenazas naturales y antrópicas. Presas y diques, entre otras obras de defensa, son infraestructuras críticas cuyo objetivo es reducir la probabilidad de inundación. Sin embargo, su fallo puede resultar en consecuencias para la comunidad situada aguas abajo, incluyendo no sólo daños económicos sino también pérdida potencial de vidas. Siempre existe una cierta probabilidad asociada al fallo de estas infraestructuras, aunque en general muy baja. El objetivo de la investigación llevada a cabo en la presente tesis doctoral, con título "Integrated flood risk management: towards a risk-informed decision making incorporating natural and human-induced hazards", es proporcionar un marco que fomente la gestión integral del riesgo de inundación desde una perspectiva multi-amenaza, considerando las necesidades actuales en la toma de decisiones para la gestión del riesgo de inundación y analizando la complejidad de sistemas con múltiples componentes, afectados por diferentes amenazas. La tesis se estructura en tres partes principales, incluyendo: (a) Parte I, una metodología para proporcionar un marco común para la identificación y caracterización del riesgo de inundación por inundación pluvial, fluvial y fallo de presas, incorporando información sobre solicitaciones, respuesta del sistema y consecuencias en modelos de riesgo que permiten analizar y evaluar el riesgo social y económico por inundación, (b) Parte II, un método para la cuantificación y análisis del riesgo en sistemas complejos presa-dique, con el objetivo de incorporar información referente al fallo de diques en la metodología propuesta en la Parte I, y analizar el riesgo social y económico por inundación incluyendo el fallo de varias infraestructuras de defensa, y (c) Parte III, una herramienta de cribado que permite caracterizar el impacto de amenazas de origen antrópico en el riesgo asociado al fallo de presas. Los resultados de esta investigación demuestran que el uso de modelos de riesgo proporciona un marco lógico y matemáticamente riguroso para la consideración de toda la información necesaria para la adecuada caracterización y análisis del riesgo de inundación por amenazas naturales y por fallo o mal funcionamiento de obras de defensa. El marco metodológico propuesto y las aplicaciones descritas en esta tesis tienen como objetivo impulsar la aplicación del análisis de riesgo por parte de los actores clave en la gestión del riesgo de inundación (gestores de infraestructuras, autoridades locales, gestores de emergencias, etc.) y demostrar en qué medida estos análisis pueden contribuir a alcanzar un mejor conocimiento de los factores clave que componen el riesgo e informar en la toma de decisiones hacia una reducción del riesgo más eficiente.
La reducció del risc d'inundació és un repte global. La societat actual demana majors nivells de seguretat, incloent-hi la realització d'accions vinculades a la protecció de les infraestructures de defensa enfront del risc d'inundacions afectades per amenaces naturals i antròpiques. Preses i dics fluvials, entre altres obres de defensa, són infraestructures crítiques i tenen l'objectiu de reduir la probabilitat d'inundació però el seu trencament pot resultar en conseqüències en, danys econòmics i també pèrdua potencial de vides. Sempre hi ha una certa probabilitat vinculada al trencament d'aquestes infraestructures, encara que en general molt baixa. L'objectiu de la investigació duta a terme en aquesta tesi doctoral, amb títol "Integrated flood risk management: towards a risk-informed decision making incorporating natural and human-induced hazards", és proporcionar un marc per a fomentar la gestió integral del risc d'inundació des d'una perspectiva multi-amenaça, tenint en compte les necessitats actuals per prendre decisions per a la gestió del risc d'inundació i analitzant sistemes complexes amb múltiples components i afectats per diferents amenaces. La tesi s'estructura en tres parts principals: (a) Part I, una metodologia proposada per a proporcionar un marc comú per a la identificació i caracterització del risc d'inundació per inundació pluvial, fluvial i trencament de preses, incorporant informació de sol¿licitacions, resposta del sistema i conseqüències en models de risc que permeten analitzar el risc social i econòmic per inundació, (b) Part II, un mètode per a la quantificació i anàlisi del risc en sistemes complexes, amb l'objectiu d'incorporar informació referent al trencament de dics fluvials en la metodologia descrita en la Part I, i analitzar el risc social i econòmic pel trencament de diverses infraestructures de defensa, i (c) Part III, una ferramenta de pre-anàlisi per a caracteritzar l'impacte d'amenaces de origen antròpic en el risc associat al trencament de preses. Els resultats de la investigació demostren l'utilitat de l'aplicació de models de risc, proporcionant un marc lògic i matemàticament rigorós per a la consideració de tota la informació necessària per a l'adequada caracterització i anàlisi del risc d'inundació per amenaces naturals i per trencament d'obres de defensa. El marc metodològic i les aplicacions derivades d'aquesta tesi tenen com a objectiu impulsar l'aplicació d'anàlisi de risc quantitatius per part dels actors vinculats a la gestió del risc d'inundació (gestors d'infraestructures, autoritats locals, gestors d'emergències, etc.) i demostrar que poden contribuir a disposar d'un millor coneixement dels factors clau que componen el risc, i per a informar les decisions necessàries per a una reducció del risc més eficient.
Castillo Rodríguez, JT. (2017). INTEGRATED FLOOD RISK MANAGEMENT: TOWARDS A RISK-INFORMED DECISION MAKING INCORPORATING NATURAL AND HUMAN-INDUCED HAZARDS [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/82305
TESIS

In the last half century, the aerospace industry has seen a dramatic paradigm shift from a focus on performance-at-any-cost to product economics and value. The steady increase in product requirements, complexity and global competition has driven aircraft manufacturers to seek broad portfolios of advanced technologies. The development costs and cycle times of these technologies vary widely, and the resulting design environment is one where decisions must be made under substantial uncertainty. Modeling and simulation have recently become the standard practice for addressing these issues; detailed simulations and explorations of candidate future states of these systems help reduce a complex design problem into a comprehensible, manageable form where decision factors are prioritized. While there are still fundamental criticisms about using modeling and simulation, the emerging challenge becomes ``How do you best configure uncertainty analyses and the information they produce to address real world problems?” One such analysis approach was developed in this thesis by structuring the input, models, and output to answer questions about the risk and economic impact of technology decisions in future aircraft programs. Unlike other methods, this method placed emphasis on the uncertainty in the cumulative cashflow space as the integrator of economic viability. From this perspective, it then focused on exploration of the design and technology space to tailor the business case and its associated risk in the cash flow dimension. The methodology is called CASSANDRA and is intended to be executed by a program manager of a manufacturer working of the development of future concepts. The program manager has the ability to control design elements as well as the new technology allocation on that aircraft. She is also responsible for the elicitation of the uncertainty in those dimensions within control as well as the external scenarios (that are out of program control). The methodology was applied on a future single-aisle 150 passenger aircraft design. The overall methodology is compared to existing approaches and is shown to identify more economically robust design decisions under a set of at-risk program scenarios. Additionally, a set of metrics in the uncertain cumulative cashflow space were developed to assist the methodology user in the identification, evaluation, and selection of design and technology. These metrics are compared to alternate approaches and are shown to better identify risk efficient design and technology selections. At the modeling level, an approach is given to estimate the production quantity based on an enhanced Overall Evaluation Criterion method that captures the competitive advantage of the aircraft design. This model was needed as the assumption of production quantity is highly influential to the business case risk. Finally, the research explored the capacity to generate risk mitigation strategies in to two analysis configurations: when available data and simulation capacity are abundant, and when they are sparse or incomplete. The first configuration leverages structured filtration of Monte Carlo simulation results. The allocation of design and technology risk is then identified on the Pareto Frontier. The second configuration identifies the direction of robust risk mitigation based on the available data and limited simulation ability. It leverages a linearized approximation of the cashflow metrics and identifies the direction of allocation using the Jacobian matrix and its inversion.

Operating hydropower reservoirs with small storage capacity is a challenging task due to the fact that in a watershed system there usually exist multiple stakeholders with different and conflicting preferences and values. Consequently the process of planning for reservoir operation must be carried out with consideration of several, usually competing, objectives. This process becomes even more challenging during a high inflow or flooding event for three main reasons. First, the objective of minimizing adverse consequences of such an event is added to the set of objectives that the operator must deal with. Second, inflow forecast uncertainty-driven risks are highly intensified due to the high sensitivity of the outcomes to inflow forecasts. And third, the available time for making a decision is very short while comprehensive analysis is a necessity in order to make an informed decision regarding the best operational alternative. Under these circumstances, the best approach to confront this challenge could be developing a Risk-Informed Decision Making (RIDM) framework that provides operation planning engineers with a solid and pre-designed guideline to deal with the task of identifying the best operational alternative in an efficient and timely manner. The current study is an attempt to apply the virtual structure of a RIDM framework for the Cheakamus River system in British Columbia. The framework is a coherent assembly of a number of methods and tools we have either developed or utilized from the existing widely used methods and techniques in practice. The product of our work is an example of the necessary tools that need to be used to develop recommendations for operating Daisy Lake reservoir during a high inflow event in a manner that all the operational objectives are served in the best possible way. This is done while taking into account making trade-offs among competing objectives. We illustrate the practical applicability and merits of the framework through applying it to a historical high inflow period in October 2003. The outcome is near real-time decisions with less dependency on only planners’ judgement and more dependency on thorough and systematic analysis with consideration of human judgement and possible risk tolerances.

The importance of fire as a potential initiator of multiple-system failures took on a new perspective after the cable-tray fire at Browns Ferry in 1975 The review have shown that the first generation Nuclear Power Plant (NPP) fire safety was not factored as high risk area that needed to be effectively assessed and quantified. This resulted in development of peculiar fire safety regulations, standards and expensive backfits. Lack of appropriate regulations and effective methods of fire risk assessment, prescriptive, difficult and expensive retrofit regulations were instituted in USA. The alternative risk-informed performance based regulation was established in USA to resolve the challenges of the prescriptive rules. The review have revealed that both the prescriptive and risk-informed performance based approaches will not represent adequate design basis for new Nuclear Power Plants. The Japanese were pulled in the path of renew fire safety regulations and risk quantification after the Fukushima accident. It has been recognized that effective fire safety assessment, and culture, in concert with countermeasures to prevent, detect, suppress, and mitigate the effect of fires if they occur, will minimized NPP fire risk. Among the numerous recommendation the fire safety at NPP must be planned and engineered before construction begin using the state-of-the-arts technology. Also, the methods of fire risk assessment must integrate the state-of-the-arts deterministic and probabilistic approaches. Two methods are presented which serve to incorporate the fire-related risk into the current practices in nuclear power plants with respect to the assessment of configurations. The first method is a fire protection systems and key safety functions Unavailability Matrix (UM) which is developed to identify structures, systems, and components significant for fire-related risk. The second method is a fire zones and key safety functions (KSFs) fire risk matrix which is useful to identify fire zones which are candidates for risk management actions. The UM is an innovative tool to communicate fire risk. The Monte Carlo method has been used to assess the uncertainty of the UM. The analysis shows that the uncertainty is sufficiently bounded. The significant fire-related risk is localized in six KSF representative components and one fire protection system which should be included in the maintenance rule. The unavailability of fire protection systems does not significantly affect the risk. The fire risk matrix identifies the fire zones that contribute the most to the fire-related risk. These zones belong to the control building and electric penetrations building. The aggregation of Internal Events PSA model and Fire PSA model have shown that the Fire PSA contributes 38.4% to the Risk increase. The feasibility of developing Fire-related Risk Monitor from the FIRE PSA for the Spanish NPP was carried out. One of the main challenges is that RiskSpectrum® fire PSA has 384 fire cases and 384 CDF but in Risk Monitor one CDF is required. However, CAFTA is unable to convert a Sequential Fault Tree structure of the internal Event tree in the Fire PSA. The conversion fails to implement neither all of the sequences leading to core damage nor the Fault Tree selection of the frequency of fire. The proposal is to suppress exchange events and introduce the alignment of the consequences so that a unique result of core damage can be quantified. The detection and fire suppression Event Trees in the reference model were replaced by detection and fire extinction Fault trees. The frequency of each Fire Case of the conversion model and the reference model are quantified and the frequencies compared. The results shows that 90% of the cases are valid, however, the rest have challenges with MCS. A unique CDF of 7.65x10-7 is quantified compared with 9.83×10-6 of the reference. The conversion of the new model in CAFTA was not successful due to software incompatibility.
La importància del incendi com un potencial iniciador de sistema múltiples fallides van agafar una nova perspectiva després del incendi al cable-safata de Browns Ferry el 1975. La revisió ha mostrat que la primera generació de seguretat contra incendis de centrals d'Energia Nuclear (NPP) no va ser àrea de alt risc, àrea que necessitava ser efectivament avaluada i quantificada. Això va resultar en el desenvolupament de normes de seguretat de incendi peculiar, estàndards i cares revisions. La manca d'una reglamentació adequada i mètodes eficaços d'avaluació de risc d'incendi, va fer que als USA foren instituïts mètodes d'adaptació de normativa preceptius, difícils i costós. L'alternativa de regulació informada per el risc es va establir als USA per resoldre els reptes de la regulació preceptiva. La revisió ha mostrat que tant als enfocaments de normativa preceptiva i regulació informada per el risc no representen bases de disseny adequades per a noves NPP. Ha estat reconeguda que la efectiva avaluació de seguretat al incendi i la cultura en concert amb mesures per prevenir, detectar, suprimir i mitigar l'efecte d'incendis, si es produeixen, minimitzarà el risc d'incendi en una NPP. Entre les nombroses recomanacions la seguretat contra incendis a una NPP s'hauran previst i dissenyat abans de començar la construcció i utilitzant estat del art de la tecnologia. També, els mètodes d'avaluació del risc d'incendi tindran que integrar el estat del art en els enfocaments de determinista i probabilístics. Dos mètodes són presentats que serveixen per incorporar el risc relacionats amb el foc a les pràctiques actuals en centrals nuclears en respecte a l'avaluació de configuracions. El primer mètode és un sistema de protecció contra incendis i una matriu de indisponiblitats de les funcions clau de seguretat (MU) que es desenvolupa per a identificar estructures, sistemes i components significatius per riscos relacionats amb els incendis. El segon mètode és zones de focs i matriu de risc d'incendi i funcions (KSFs) clau de seguretat que és útil identificar les zones de foc que són candidats per a les accions de gestió de risc. La MU és una eina innovadora per comunicar el risc d'incendi. El risc significatiu relacionats amb el incendi està localitzat en sis components representatius KSF i un sistema de protecció de foc que cal que figuri en la regla de manteniment. La manca de sistemes de protecció contra incendis no afecta significativament al risc. La matriu de risc d'incendi identifica les zones de foc que mes contribueixen al risc relacionats amb el incendi. Aquestes zones pertanyen a l'edifici de control i edifici de penetracions elèctriques. L'agregació del model de PSA de esdeveniments interns i model de incendis PSA han demostrat que el PSA de incendis aporta 38.4% a l'augment de risc. S'ha desenvolupat la viabilitat del Monitor de risc de incendis a partir del PSA de incendis per a una central nuclear espanyola. Un dels reptes principals és que RiskSpectrum® incendis PSA te 384 casos de incendis i te 384 CDF però en risc Monitor és necessària una CDF. Tanmateix, el CAFTA és incapaç de convertir una estructura seqüencial de arbre de fallida de l'arbre esdeveniment interna en el PSA de incendis. La conversió fracassa al posar en pràctica totes les seqüències de danys al nucli i la selecció de l'arbre de fallida de la freqüència de incendi. La descoberta i supressió de arbres de l'esdeveniment de incendi en el model de referència es van substituir per detecció i els arbres de fallades d'extinció d'incendi. La freqüència de cada cas de incendi del model de conversió i el model de referència son quantificades i les freqüències son comparades. Els resultats demostra que el 90% dels casos són vàlid, no obstant això, la resta té reptes amb MCS. Un únic CDF de 7.65x10-7 s'ha quantificat en comparació amb 9.83 × 10-6 de la referència. La conversió del nou model a CAFTA no va tenir èxit a causa de la incompatibilitat del programari.

[ES] Las grandes presas, así como los diques de protección, son infraestructuras críticas cuyo fallo puede conllevar importantes consecuencias económicas y sociales. Tradicionalmente, la gestión del riesgo y la definición de estrategias de adaptación en la toma de decisiones han asumido la invariabilidad de las condiciones climáticas, incluida la persistencia de patrones históricos de variabilidad natural y la frecuencia de eventos extremos. Sin embargo, se espera que el cambio climático afecte de forma importante a los sistemas hídricos y comprometa la seguridad de las presas, lo que puede acarrear posibles impactos negativos en términos de costes económicos, sociales y ambientales. Los propietarios y operadores de presas deben por tanto adaptar sus estrategias de gestión y adaptación a medio y largo plazo a los nuevos escenarios climáticos. En la presente tesis se ha desarrollado una metodología integral para incorporar los impactos del cambio climático en la gestión de la seguridad de presas y en el apoyo a la toma de decisiones. El objetivo es plantear estrategias de adaptación que incorporen la variabilidad de los futuros riesgos, así como la incertidumbre asociada a los nuevos escenarios climáticos. El impacto del cambio climático en la seguridad de presas se ha estructurado utilizando modelos de riesgo y mediante una revisión bibliográfica interdisciplinaria sobre sus potenciales efectos. Esto ha permitido establecer un enfoque dependiente del tiempo que incorpore la evolución futura del riesgo, para lo cual se ha definido un nuevo indicador que evalúa cuantitativamente la eficiencia a largo plazo de las medidas de reducción de riesgo. Además, para integrar la incertidumbre de los escenarios futuros en la toma de decisiones, la metodología propone una estrategia robusta que permite establecer secuencias optimizadas de implementación de medidas correctoras para la adaptación al cambio climático. A pesar de las dificultades para asignar probabilidades a eventos específicos, esta metodología permite un análisis sistemático y objetivo, reduciendo considerablemente la subjetividad. Esta metodología se ha aplicado al caso real de una presa española susceptible a los efectos del cambio climático. El análisis se centra en el escenario hidrológico, donde las avenidas son la principal carga a la que está sometida la presa. Respecto de análisis previos de la presa, los resultados obtenidos proporcionan nueva y valiosa información sobre la evolución de los riesgos futuros y sobre cómo abordarlos. En general, se espera un aumento del riesgo con el tiempo; esto ha llevado a plantear nuevas medidas de adaptación que no están justificadas en la situación actual. Esta es la primera aplicación documentada de un análisis exhaustivo de los impactos del cambio climático sobre el riesgo de rotura de una presa que sirve como marco de referencia para la definición de estrategias de adaptación a largo plazo y la evaluación de su eficiencia.
[CAT] Les grans preses, així com els dics de protecció, són infraestructures crítiques que si fallen poden produir importants conseqüències econòmiques i socials. Tradicionalment, la gestió del risc i la definició d'estratègies d'adaptació en la presa de decisions han assumit la invariabilitat de les condicions climàtiques, inclosa la persistència de patrons històrics de variabilitat natural i la probabilitat d'esdeveniments extrems. No obstant això, s'espera que el canvi climàtic afecte de manera important als sistemes hídrics i comprometi la seguretat de les preses, la qual cosa pot implicar possibles impactes negatius en termes de costos econòmics, socials i ambientals. Els propietaris i operadors de preses deuen per tant adaptar les seues estratègies de gestió i adaptació a mitjà i llarg termini als nous escenaris climàtics. En la present tesi s'ha desenvolupat una metodologia integral per a incorporar els impactes del canvi climàtic en la gestió de la seguretat de preses i en el suport a la presa de decisions. L'objectiu és plantejar estratègies d'adaptació que incorporen la variabilitat dels futurs riscos, així com la incertesa associada als nous escenaris climàtics. L'impacte del canvi climàtic en la seguretat de preses s'ha estructurat utilitzant models de risc i mitjançant una revisió bibliogràfica interdisciplinària sobre els seus potencials efectes. Això ha permès establir un enfocament dependent del temps que incorpori l'evolució futura del risc, per a això s'ha definit un nou indicador que avalua quantitativament l'eficiència a llarg termini de les mesures de reducció de risc. A més, per a integrar la incertesa dels escenaris futurs en la presa de decisions, la metodologia proposa una estratègia robusta que permet establir seqüències optimitzades d'implementació de mesures correctores per a l'adaptació al canvi climàtic. A pesar de les dificultats per a assignar probabilitats a esdeveniments específics, esta metodologia permet una anàlisi sistemàtica i objectiva, reduint considerablement la subjectivitat. Aquesta metodologia s'ha aplicat al cas real d'una presa espanyola susceptible a l'efecte del canvi climàtic. L'anàlisi se centra en l'escenari hidrològic, on les avingudes són la principal càrrega a la qual està sotmesa la presa. Respecte d'anàlisis prèvies de la presa, els resultats obtinguts proporcionen nova i valuosa informació sobre l'evolució dels riscos futurs i sobre com abordar-los. En general, s'espera un augment del risc amb el temps; això ha portat a plantejar noves mesures d'adaptació que no estarien justificades en la situació actual. Aquesta és la primera aplicació documentada d'una anàlisi exhaustiva dels impactes del canvi climàtic sobre el risc de trencament d'una presa que serveix com a marc de referència per a la definició d'estratègies d'adaptació a llarg termini i l'avaluació de la seua eficiencia.
[EN] Large dams as well as protective dikes and levees are critical infrastructures whose failure has major economic and social consequences. Risk assessment approaches and decision-making strategies have traditionally assumed the stationarity of climatic conditions, including the persistence of historical patterns of natural variability and the likelihood of extreme events. However, climate change has a major impact on the world's water systems and is endangering dam safety, leading to potentially damaging impacts in terms of economic, social and environmental costs. Owners and operators of dams must adapt their mid- and long-term management and adaptation strategies to new climate scenarios. This thesis proposes a comprehensive approach to incorporate climate change impacts on dam safety management and decision-making support. The goal is to design adaptation strategies that incorporate the non-stationarity of future risks as well as the uncertainties associated with new climate scenarios. Based on an interdisciplinary review of the state-of-the-art research on its potential effects, the global impact of climate change on dam safety is structured using risk models. This allows a time-dependent approach to be established to consider the potential evolution of risk with time. Consequently, a new indicator is defined to support the quantitative assessment of the long-term efficiency of risk reduction measures. Additionally, in order to integrate the uncertainty of future scenarios, the approach is enhanced with a robust decision-making strategy that helps establish the consensus sequence of measures to be implemented for climate change adaptation. Despite the difficulties to allocate probabilities to specific events, such framework allows for a systematic and objective analysis, reducing considerably the subjectivity. Such a methodology is applied to a real case study of a Spanish dam subjected to the effects of climate change. The analysis focus on hydrological scenarios, where floods are the main load to which the dam is subjected. The results provide valuable new information with respect to the previously existing analysis of the dam regarding the evolution of future risks and how to cope with it. In general, risks are expected to increase with time and, as a result, new adaptation measures that are not justifiable for the present situation are recommended. This is the first documented application of a comprehensive analysis of climate change impacts on dam failure risk and serves as a reference benchmark for the definition of long-term adaptation strategies and the evaluation of their efficiency.
Fluixá Sanmartín, J. (2020). Adaptation strategies of dam safety management to new climate change scenarios informed by risk indicators [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/157634
TESIS

Cette thèse de doctorat aborde le problème de l'agrégation de risques multiple (MHRA), qui vise à agréger les risques estimés pour différents contributeurs. La pratique actuelle de la MHRA est basée sur une sommation arithmétique simple des estimations de risques. Cependant, ces estimations sont obtenues à partir de modèles EPS (Estimation Probabiliste de risque) qui présentent des degrés de réalisme différents liés à différents niveaux de connaissances. En ne prenant pas en compte ces différences, le processus MHRA pourrait conduire à des résultats trompeurs pour la prise de décision (DM). Dans cette thèse, un cadre structuré est proposé afin d’évaluer le niveau de réalisme et de confiance dans les évaluations de risques et de l’intégrer dans le processus de MHRA. Ces travaux ont permis : (i) Une identification des facteurs contribuant à la fiabilité de l'évaluation des risques. Leurs criticités sont analysées afin de comprendre leur influence sur l’estimation des risques; (ii) Un cadre hiérarchique intégré est développé pour évaluer la confiance et le réalisme de l'estimation de risque, sur la base des facteurs et des attributs identifiés en (i); (iii) Une méthode basée sur un modèle réduit est proposée pour évaluer efficacement la fiabilité de l'évaluation des risques dans la pratique. Grâce à cette méthode, le nombre d'éléments pris en compte dans l'évaluation initiale des risques peut être limité. (iv) Une technique qui combine la théorie de Dempster-Shafer et le processus de hiérarchie analytique (DST-AHP) est appliquée au modèle développé. Cette technique permet d’évaluer le niveau de réalisme et confiance -dans l’analyse de risque- en utilisant une moyenne pondérée des attributs: la méthode AHP est utilisée pour calculer le poids des attributs et la méthode DST est utilisée pour tenir compte de l'incertitude subjective dans le jugement des experts dans l'évaluation des poids; (v) Une technique de MHRA est développée sur la base d'un modèle de moyenne bayésienne afin de surmonter les limites de la pratique actuelle de MHRA qui néglige le réalisme et confiance dans l'évaluation de chaque contributoire de risque; (vi) Le modèle développé est appliqué sur des cas réels de l'industrie des centrales nucléaires
This PhD thesis addresses the problem of Multi-Hazards Risk Aggregation (MHRA), which aims at aggregating the risk estimates from Probabilistic Risk Assessment (PRA) models for the different contributors. The current practice of MHRA is based on a simple arithmetic summation of the risk estimates. However, the risk estimates are obtained from PRA models that have different degrees of trustworthiness, because of the different background knowledge they are based on. Ignoring this difference in MHRA could lead to misleading results for Decision-Making (DM). In this thesis, a structured framework is proposed to assess the level of trustworthiness, which risk assessment results are based on and to integrate it in the process of MHRA. The original scientific contributions are: (i) Factors contributing to the trustworthiness of risk assessment outcomes are identified and their criticalities are analyzed under different frameworks, to understand their influence on the risk results; (ii) An integrated hierarchical framework is developed for assessing the trustworthiness of risk analysis, based on the identified factors and related attributes; (iii) A reduced order model-based method is proposed to efficiently evaluate the trustworthiness of risk assessment in practice. Through the reduced-order model, the proposed method can limit the number of elements considered in the original risk assessment; (iv) A technique that combines Dempster Shafer Theory and the Analytic Hierarchy Process (namely, DSTAHP) is applied to the developed framework to assess the trustworthiness by a weighted average of the attributes in the framework: the AHP method is used to derive the weights of the attributes and the DST is used to account for the subjective uncertainty in the experts’ judgments for the evaluation of the weights; (v) A MHRA technique is developed based on Bayesian model averaging, to overcome the limitations of the current practice of risk aggregation that neglects the trustworthiness of the risk assessment of individual hazard groups; (vi) The developed framework is applied to real case studies from the Nuclear Power Plants (NPP) industry

This thesis focuses on expectant parents’ experiences and needs when soft makers are detected at mid-trimester ultrasound, resulting in an unexpected assessment of risk for fetal anomalies. The thesis also describes the prevalence of ultrasonographic fetal soft markers and the incidence of Down syndrome in a low-risk population of 10,535 pregnant women with a total of 10,710 fetuses, as well as the risk of invasive prenatal diagnostics in conjunction with the detection of soft markers. Finally, the thesis aims to explore the value of a web-based patient decision aid (DA) in facilitating informed decision making regarding routine fetal screening for anomalies and the fathers’ role in decision making regarding prenatal screening. A prospective observational study was conducted between 2008–2011 to investigate the prevalence of ultrasonographic fetal soft markers at second trimester screening. During this time period, 12 women and 17 men were interviewed about their experience when soft markers were detected. Based on the results of these interviews, a web-based decision aid (DA) to enhance expectant parents’ decision-making concerning fetal screening was developed and a trial initiated to test its utility. Interviews were conducted with 17 women who received access to the DA, 11 who had chosen to use the DA and six who had not used it. All interview studies were analysed using systematic text condensation (STC) developed by Malterud. Soft markers were detected in 5.9% of the fetuses at mid-trimester ultrasound, whereof 5.1% were isolated. All soft markers showed a positive likelihood ratio (LR+) for DS; however, the association was only statistically significant for the collapsed category ‘any marker’ (isolated, multiple or combined with anomaly), not for isolated markers. An almost 24-fold increase of invasive diagnostic testing was shown in all women, including those with a low estimated risk for aneuploidy, i.e. < 1/200 (paper III). The results from interviews showed that the finding of soft markers created much anxiety and indicated that both women and men lacked awareness of the potential of the ultrasound examination (papers I and II). The results also showed that the men were actively engaged in decision making not only by supporting their partners, but also considered their own values and needs regarding these issues (paper II). It was also evident that women wanted their partners to be engaged in decisions regarding fetal diagnostics (papers I and IV). The web-based patient DA was able to initiate a process of conscious decision making in pregnant women, as a result of their interaction with the tool. The DA allowed for clarification of women’s thoughts and priorities and helped them to understand the significance of the screening result and providing a basis for making informed decisions regarding fetal screening (paper IV).

Investments in space systems are substantial, indivisible, and irreversible, characteristics that make them high-risk, especially when coupled with an uncertain demand environment. Traditional approaches to system design and acquisition, derived from a performance- or cost-centric mindset, incorporate little information about the spacecraft in relation to its environment and its value to its stakeholders. These traditional approaches, while appropriate in stable environments, are ill-suited for the current, distinctly uncertain and rapidly changing technical, and economic conditions; as such, they have to be revisited and adapted to the present context. This thesis proposes that in uncertain environments, decision-making with respect to space system design and acquisition should be value-based, or at a minimum value-informed. This research advances the value-centric paradigm by providing the theoretical basis, foundational frameworks, and supporting analytical tools for value assessment of priced and unpriced space systems. For priced systems, stochastic models of the market environment and financial models of stakeholder preferences are developed and integrated with a spacecraft-sizing tool to assess the system's net present value. The analytical framework is applied to a case study of a communications satellite, with market, financial, and technical data obtained from the satellite operator, Intelsat. The case study investigates the implications of the value-centric versus the cost-centric design and acquisition choices. Results identify the ways in which value-optimal spacecraft design choices are contingent on both technical and market conditions, and that larger spacecraft for example, which reap economies of scale benefits, as reflected by their decreasing cost-per-transponder, are not always the best (most valuable) choices. Market conditions and technical constraints for which convergence occurs between design choices under a cost-centric and a value-centric approach are identified and discussed. In addition, an innovative approach for characterizing value uncertainty through partial moments, a technique used in finance, is adapted to an engineering context and applied to priced space systems. Partial moments disaggregate uncertainty into upside potential and downside risk, and as such, they provide the decision-maker with additional insights for value-uncertainty management in design and acquisition. For unpriced space systems, this research first posits that their value derives from, and can be assessed through, the value of information they provide. To this effect, a Bayesian framework is created to assess system value in which the system is viewed as an information provider and the stakeholder an information recipient. Information has value to stakeholders as it changes their rational beliefs enabling them to yield higher expected pay-offs. Based on this marginal increase in expected pay-offs, a new metric, Value-of-Design (VoD), is introduced to quantify the unpriced system's value. The Bayesian framework is applied to the case of an Earth Science satellite that provides hurricane information to oil rig operators using nested Monte Carlo modeling and simulation. Probability models of stakeholders' beliefs, and economic models of pay-offs are developed and integrated with a spacecraft payload generation tool. The case study investigates the information value generated by each payload, with results pointing to clusters of payload instruments that yielded higher information value, and minimum information thresholds below which it is difficult to justify the acquisition of the system. In addition, an analytical decision tool, probabilistic Pareto fronts, is developed in the Cost-VoD trade space to provide the decision-maker with additional insights into the coupling of a system's probable value generation and its associated cost risk.

Research and Development engineering is at the corner stone of humanity’s evolution. It is perceived to be a systematic creative process which ultimately improves the living standard of a society through the creation of new applications and products. The commercial paradigm that governs project selection, resource allocation and market penetration prevails when the focus shifts from pure research to applied research. Furthermore, the road to success through commercialisation is difficult for most inventors, especially in a vast and isolated country such as Australia which is located a long way from wealthy and developed economies. While market leading products are considered unique, the actual process to achieve these products is essentially the same; progressing from an idea, through development to an outcome (if successful). Unfortunately, statistics indicate that only 3% of ‘ideas’ are significantly successful, 4% are moderately successful, and the remainder ‘evaporate’ in that form (Michael Quinn, Chairman, Innovation Capital Associates Pty Ltd). This study demonstrates and analyses two techniques developed by the author which reduce uncertainty in the engineering design and development phase of new product development and therefore increase the probability of a successful outcome. This study expands the existing knowledge of the engineering design and development stage in the new product development process and is couched in the identification of practical methods, which have been successfully used to develop new products by Australian Small Medium Enterprise (SME) Excel Technology Group Pty Ltd (ETG). Process theory is the term most commonly used to describe scientific study that identifies occurrences that result from a specified input state to an output state, thus detailing the process used to achieve an outcome. The thesis identifies relevant material and analyses recognised and established engineering processes utilised in developing new products. The literature identified that case studies are a particularly useful method for supporting problem-solving processes in settings where there are no clear answers or where problems are unstructured, as in New Product Development (NPD). This study describes, defines, and demonstrates the process of new product development within the context of historical product development and a ‘live’ case study associated with an Australian Government START grant awarded to Excel Technology Group in 2004 to assist in the development of an image-based vehicle detection product. This study proposes two techniques which reduce uncertainty and thereby improve the probability of a successful outcome. The first technique provides a predicted project development path or forward engineering plan which transforms the initial ‘fuzzy idea’ into a potential and achievable outcome. This process qualifies the ‘fuzzy idea’ as a potential, rationale or tangible outcome which is within the capability of the organisation. Additionally, this process proposes that a tangible or rationale idea can be deconstructed in reverse engineering process in order to create a forward engineering development plan. A detailed structured forward engineering plan reduces the uncertainty associated with new product development unknowns and therefore contributes to a successful outcome. This is described as the RETRO technique. The study recognises however that this claim requires qualification and proposes a second technique. The second technique proposes that a two dimensional spatial representation which has productivity and consumed resources as its axes, provides an effective means to qualify progress and expediently identify variation from the predicted plan. This spatial representation technique allows a quick response which in itself has a prediction attribute associated with directing the project back onto its predicted path. This process involves a coterminous comparison between the predicted development path and the evolving actual project development path. A consequence of this process is verification of progress or the application of informed, timely and quantified corrective action. This process also identifies the degree of success achieved in the engineering design and development phase of new product development where success is defined as achieving a predicted outcome. This spatial representation technique is referred to as NPD Mapping. The study demonstrates that these are useful techniques which aid SMEs in achieving successful new product outcomes because the technique are easily administered, measure and represent relevant development process related elements and functions, and enable expedient quantified responsive action when the evolving path varies from the predicted path. These techniques go beyond time line representations as represented in GANTT charts and PERT analysis, and represent the base variables of consumed resource and productivity/technical achievement in a manner that facilitates higher level interpretation of time, effort, degree of difficulty, and product complexity in order to facilitate informed decision making. This study presents, describes, analyses and demonstrates an SME focused engineering development technique, developed by the author, that produces a successful new product outcome which begins with a ‘fuzzy idea’ in the mind of the inventor and concludes with a successful new product outcome that is delivered on time and within budget. Further research on a wider range of SME organisations undertaking new product development is recommended.

A gap exists in the methods used in industry and available in academia that prevents customers and engineers from having a voice when considering engineering risk appetite in the dynamic shaping of early-phase conceptual design trade study outcomes. Current methods used in Collaborative Design Centers either collect risk information after a conceptual design has been created, treat risk as an afterthought during the trade study process, or do not consider risk at all during the creation of conceptual designs. This dissertation proposes a risk-informed decision making framework that offers a new way to account for risk and make decisions based upon risk information within conceptual complex system design trade studies. A meaningful integration of the consideration of risk in trade studies is achieved in this framework thus elevating risk to the same level as other important system-level design parameters. Trade-offs based upon risk appetites of individuals are explicitly allowed under the framework, enabled by an engineering-specific psychometric risk survey that provides aspirational information to use in utility functions. This dissertation provides a novel framework and supporting methodologies for risk-informed design decisions and trades to be made that are based upon engineering risk appetites in conceptual design trade studies.
Graduation date: 2012

Different people can have different cultural interpretations of the person—atomic versus embedded—and these may affect health care decision-making. This study examines both the ethics of variations in personhood as well as their implications for the doctrine of informed consent and the duty to warn of genetic disease risk. It argues that variations in personhood are consistent with the ethics of the Principle of Autonomy and the Canadian stand on informed consent, though autonomy and consent play out differently in practice on the two models. Also as a result of different interpretations of the person, the duty to warn of hereditary risk is found to be relevant to the atomic conception but unnecessary among embedded individuals.
Graduate
0422
0566
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pkdheri@uvic.ca

While many organizations claim to "put safety first," safety is rarely considered early in the design process when system-level architectural decisions are made. Instead, system design follows an abstraction-to-detail process to first meet functional and then performance requirements. Following this process, safety assurance occurs in the later stages of design through a rigorous expert review process. The significant cost of safety-based redesign and the growing complexity of engineered systems motivates a need for early design-stage fault analysis. This research presents a novel method of including safety into the model-based design and analysis of complex systems using low-fidelity behavior simulations. Specifically, this research demonstrates the adaption of the functional design process to explicitly include the system property of safety in the system representation. Next, early design fault analysis is extended to connect component failure behavior to system-level hazards. Finally, this research develops three methods of results clustering to provide different evaluation metrics of the system design. In summary, this research demonstrates a framework for incorporating safety into early design decision making. This research addresses safety and failure in the design of complex systems incorporating diverse technology domains as found in energy, transportation, and aerospace systems.
Graduation date: 2012