Browsing by Subject "risk assessment"
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Item Analytical foundations of physical security system assessment(Texas A&M University, 2006-10-30) Graves, Gregory HowardPhysical security systems are intended to prevent or mitigate potentially catastrophic loss of property or life. Decisions regarding the selection of one system or configuration of resources over another may be viewed as design decisions within a risk theoretic setting. The problem of revealing a clear preference among design alternatives, using only a partial or inexact delineation of event probabilities, is examined. In this dissertation, an analytical framework for the assessment of the risk associated with a physical security system is presented. Linear programming is used to determine bounds on the expected utility of an alternative, and conditions for the separation of preferences among alternatives are shown. If distinguishable preferences do not exist, techniques to determine what information may help to separate preferences are presented. The linear programming approach leads to identification of vulnerabilities in a security system through an examination of the solution to the dual problem. Security of a hypothetical military forward operating base is considered as an illustrative example. For two alternative security schemes, the uncertainty inherent in the scenario is represented using probability assessments consisting of bounds on event probabilities and exact probability assignments. Application of the framework reveals no separation of preferences between the alternatives. Examination of the primal and dual solutions to the linear programming problems, however, reveals insights into information which, if obtained, could lead to a separation of preferences as well as information on vulnerabilities in one of the alternative security postures.Item Hurricane Surge Flooding Damage Assessment and Web-Based Game Development to Support K12 Education for Understanding Climate Change Impact on Hurricane Surge Flooding Damage(2014-08-10) Hsu, Chih-HungHurricane surge floods have caused devastating damage along coastal areas all over the world. Yet many recent studies have shown that global warming could increase the hurricane flooding damage by hurricane intensification and sea level rise. Hence, the ability to predict surge elevations and to use this information for damage estimation is fundamental for saving lives and protecting property. In this study, we developed a framework that allows one to acquire information of hurricane flooding damage (e.g. structural damage, population being affected, flooded area, etc.) for different hurricanes. This framework is based on Surge Response Functions (SRFs). SRFs are physical scaling laws derived from a suite of discrete ADvanced CIRCulation Model (ADCIRC) simulations and represent surge values as a function of hurricane parameters. The advantage of this SRF-based approach is that a large number of storms can be efficiently evaluated and considered in the analysis, without losing accuracy in the surge estimates. To extrapolate the surge water elevation inland, SRF zones were defined within which the water elevation was considered horizontal. Individual parcel flood damage was calculated based on the flood water depth and damage vs. water depth curves included in the Federal Emergency Management Agency?s (FEMA) application HAZUS. Parcel data (property value, population) and business data (employee size, and sales volume) are collected and used to conduct risk analysis under different future climate scenarios. Expected changes for future climate scenarios (i.e., IPCC scenarios B1, A1B and A1FI for the 2030?s and 2080?s) were considered by accounting for projected sea surface temperature increases and sea level rise, which modify the probability distribution of hurricane central pressure and change the baseline of damage calculation, respectively. Flood risk estimates and maps are developed for Corpus Christi in Texas, and Gulfport in Mississippi. For the case of Corpus Christi, it was found that, as the projected sea surface temperature increased, higher surge values are more likely to occur, as expected, resulting in higher expected damage. The risk map of Port Aransas in the Corpus Christi area, for example, shows that the risk is in the range of 1% to 4% of the property value for current climate conditions, and shifts to 1% to 8% for the 2030?s and 1% to 14% for the 2080?s. The concept of the parameterized hurricane damage analysis is also used to construct a web-based game ?VisHurricane? which is intent to be used as an educational tool for K-12 students to arise their attention of current issues on climate change and potential future hurricane surge flooding risk.Item Incorporating Risk and Uncertainty into Pavement Network Maintenance and Rehabilitation Budget Allocation Decisions(2014-07-30) Menendez Acurio, Jose RafaelAccording to the American Society of Civil Engineers, 33% of the United States? major roads are in poor or mediocre condition with a projected funding shortfall of $549.5 billion for 2010?2015. Environmental factors, increased traffic, and lack of adequate maintenance are causing many of these roads to deteriorate faster. The imbalance between maintenance needs and available funds tends to become more critical over time, demanding more reliable and advanced tools for allocating funds and prioritizing projects. In 2012, the U.S. Congress passed the Moving Ahead for Progress in the 21st Century Act (MAP-21) to fund surface transportation programs for 2013?2014 and beyond. MAP-21 establishes a framework for federal transportation investments with the goals of preserving the highway system while improving its condition and performance. This law requires states to develop risk-based asset management plans that include risk management analysis. In order to fulfill MAP-21 requirements, pavement management systems must be upgraded to incorporate risk management, permitting pavement management systems to serve as a more realistic decision support tool for planning and budget allocation in pavement maintenance and rehabilitation. This dissertation aims to incorporate risk assessment into maintenance and rehabilitation budget decisions at the planning stage. For risk assessment, uncertainty was incorporated into the analysis process, and factors influencing decisions are modeled as probability distributions. The factors included are pavement conditions, available funds, maintenance and rehabilitation costs, and performance prediction. The risk for each scenario is defined as the probability of failing to achieve pre-defined performance goals. The results of this research show that the benefit-cost budget allocation method has the lowest risk to fail to achieve the performance goals. The maintenance-first method has slightly higher risk but averages scores are better compared with benefit-cost. The method with highest risk is the rehabilitation-first, which have a significant difference with all the other allocation methods. This research demonstrates that incorporating uncertainty and risk assessment into pavement management can lead to better-informed decision and ultimately improved M&R budget allocation policies. This work provides DOTs with analytical tools and methods for meeting the requirements of MAP-21.Item Interdependent infrastructures and multi-mode attacks and failures: improving the security of urban water systems and fire response(2009-05-15) Bristow, Elizabeth CatherineThis dissertation examines the interdependence between urban water distribution systems and urban fire response. The focus on interdependent critical infrastructures is driven by concern for security of water systems and the effects on related infrastructures if water distribution systems are damaged by terrorist attack or natural disaster. A model of interdependent infrastructures (principally water distribution systems and fire response) is developed called the Model of Urban Fire Spread (MUFS). The model includes the capacity to simulate firefighting water demands in a community water system hydraulic model, building-to-building urban fire spread, and suppression activities. MUFS is an improvement over previous similar models because it allows simulation of urban fires at the level of individual buildings and it permits simulation of interdependent infrastructures working in concert. MUFS is used to simulate a series of multi-mode attacks and failures (MMAFs) ? events which disable the water distribution system and simultaneously ignite an urban fire. The consequences of MMAF scenarios are analyzed to determine the most serious modes of infrastructure failure and urban fire ignition. Various methods to determine worst-case configurations of urban fire ignition points are also examined. These MMAF scenarios are used to inform the design of potential mitigation measures to decrease the consequences of the urban fire. The effectiveness of mitigation methods is determined using the MUFS simulation tool. Novel metrics are developed to quantify the effectiveness of the mitigation methods from the time-series development of their consequences. A cost-benefit analysis of the various mitigation measures is conducted to provide additional insight into the methods? effectiveness and better inform the decision-making process of selecting mitigation methods. Planned future work includes further refinement of the representation of fire propagation and suppression in MUFS and investigation of historical MMAF events to validate simulation predictions. Future efforts will continue development of appropriate optimization methods for determining worst-case MMAF scenarios. This work should be of interest to water utility managers and emergency planners, who can adapt the methodology to analyze their communities? vulnerability to MMAFs and design mitigation techniques to meet their unique needs, as well as to researchers interested in infrastructure modeling and disaster simulation.Item Pesticide impact on non-target wildlife in irrigated crops: simulated impact of cholinesterase-inhibiting pesticides on white-winged doves in the Lower Rio Grande Valley of Texas(Texas A&M University, 2007-09-17) Pisani, Jorge MarceloI present a simulation model that should be a useful tool for risk assessment of the impact of insecticide inhibitors of cholinesterase (ChE) applied in irrigated agricultural fields on non-target wildlife. I developed the model as a compartment model based on difference equations (????t = 1 hour) and programmed with Stella???? VII software. Conceptually the model is compartmentalized into six submodels describing the dynamics of (1) insecticide application, (2) insecticide movement into floodable soil, (3) irrigation and rain, (4) insecticide dissolution in water, (5) foraging and insecticide intake from water, and (6) ChE inhibition and recovery. To demonstrate application of the model, I simulate historical, current, and ??????worst-case?????? scenarios, that examined the impact of ChE-inhibiting insecticides on white-winged doves (WWDO - Zenaida asiatica) in the Lower Rio Grande Valley of Texas (LRGV), USA. To my knowledge, there are no field data verifying that the cause of ChE deprivation in WWDO is due to the ingestion of ChE-inhibiting insecticide residues dissolved in drinking water. I parameterized the model to represent a system composed of fields of cotton, sorghum, corn, citrus, and brushland that encompasses the activity range of a WWDO in the LRGV. I simulated situations representing the typical scenario of WWDO using irrigated crop fields in the absence and in the presence of rain. I also simulated ??????worst case?????? scenarios in which methyl parathion was applied at high rates and high frequency. Based on results of the simulations, I conclude that it is unlikely that WWDO are seriously exposed to ChE-inhibiting insecticides by drinking contaminated water. Only in rare cases, for example, when a rain event occurs just after the application of insecticides, are levels of ChE inhibition likely to approach diagnostic levels (20 %). The present simulation model should be a useful tool to predict the effect of ChE-inhibiting insecticides on the ChE activity of different species that drink contaminated water from irrigated agricultural fields. It should be particularly useful in identifying specific situations in which the juxtaposition of environmental conditions and management schemes could result in a high risk to non-target wildlife.Item Potential Impact of Changes in Risk Assessment to Address Wicked Problems: A Case Study of British Petroleum?s Assessment Strategies(2014-11-19) Koelsch, Cari J.In the last decade, in lieu of many financial and environmental problems, the confidence in a traditional risk management strategy has fallen. Due to issues facing the sustainability of natural resources and globalization of the oil and gas industry, problems have become too complex to solve with traditional risk management strategies. The complexities of these problems have resulted in a characterization of the problem as ?wicked problems.? Wicked problems are those that arise that are unstructured, irregular, and adaptive. In order to deal with wicked problems, different risk analysis strategies have been developed. These strategies have tried to create a beneficial form of risk analysis and management that will be more productive when dealing with wicked problems. Therefore, it should be of benefit to analyze whether broadened risk assessment and management principles for wicked problems are more environmentally sound and economically effective. Using BP as a case study, this thesis hypothesizes that the execution of broadened risk assessment and management strategies will be more effective and efficient environmentally and economically. This study examines the environmental and economic efficiency of British Petroleum (BP) in order to determine if the introduction of a broadened risk assessment strategy was beneficial. Emissions data were compiled from reported emissions records on the Environmental Protection Agency?s (EPA) greenhouse gas (GHG) data website from the years 2010-2012. Economic data were gathered through BP?s annual reports from the years 2008-2013. The data were compared through a series of environmental and economic analyses in order to determine the impact of a broadened risk assessment: The environmental data were assessed by analyzing the emissions levels and scaling the emissions by output of the company. The economic data were evaluated through two average product analyses and a risk savings analysis. The results showed an overall improvement in economic efficiency, and no environmental efficiency improvement after the introduction of a broadened risk assessment strategy.Item Quantitative Microbial Risk Assessment of Listeria monocytogenes on Fresh-cut Lettuce and Fresh-cut Cantaloupe(2015-01-21) Guzel, MustafaThe increase in foodborne illness outbreaks associated with fresh and fresh-cut produce can be attributed to ineffectiveness of current handling practices. This study describes the change on concentration of population of Listeria monocytogenes in two popular fresh-cut produces, romaine lettuce, and cantaloupe, from farm to table. Listeria innocua was used as a surrogate for L. monocytogenes to experimentally evaluate the effectiveness of washing treatments (water and chlorine) and develop growth curves under different storage temperatures (between 5 and 36oC). The findings confirm that both washing treatments were significantly more effective (p<0.05) on reducing L. innocua concentration in fresh-cut romaine lettuce than in cantaloupe. For instance, chlorinated water washing reduced L. innocua population by 0.98 log on fresh-cut romaine lettuce compared to just 0.57 log on cantaloupe rind. Furthermore, the experimental data on L. innocua were used to test three predictive models to describe the growth of L. monocytogenes in both produce. All models (Baranyi and Roberts, Gompertz, and Logistic) provided good fit of the data. However, compared to the Baranyi and Roberts model, both Gompertz and Logistic models overestimated the growth rate at temperatures of 10?C and above. Results demonstrated that these models may be used to estimate the growth in fresh-cut produce during distribution, storage or at the market, and potential growth at a consumer level. Several scenarios were created to evaluate the impact of decontamination treatments, occurrence of cross-contamination, and temperature abuse on the population of L. monocytogenes. In general, expected annual listeriosis cases associated with fresh- cut cantaloupe were higher (around 17) than with fresh-cut romaine lettuce (<1).The time of consumption of the produce was the biggest issue regarding to ensuring the safety of the fresh-cut produce. Occurrence of temperature abuse and cross- contamination also increased the risk of listeriosis in both products. Among the intervention steps, irradiation treatment was the most effective, with 99.99% reduction on the expected number of annual cases of listeriosis for both produce.