Browsing by Subject "Risk Analysis"
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Item A design approach to a risk review for fuel cell-based distributed cogeneration systems(Texas A&M University, 2004-09-30) Luthringer, Kristin LynA risk review of a fuel cell-based distributed co-generation (FC-Based DCG) system was conducted to identify and quantify the major technological system risks in a worst-case scenario. A risk review entails both a risk assessment and a risk analysis of a designed system, and it is part of risk engineering. Thorough literature reviews and expert interviews were conducted in the field of fuel cells. A thorough literature review of the risk engineering field was also conducted. A procedure for a risk review of the FC-Based DCG System was developed. The representative system design was identified by the current DCG design technology. The risk assessment was carried out, identifying the system components and potential failure modes and consequences. Then, using probabilities of failure for the various system components, the risk associated with a particular system design was determined. A Monte Carlo simulation on the total system reliability was used to evaluate the potential for system failure at a time of 1 hour, 5 hours, 10 hours, 50 hours, 100 hours and 500 hours of continuous operation. The original system was found to be acceptable at the initial times, but after 100 hours was predicted to fail. The components which consistently contribute significantly to the overall system risk are the membrane electrode assembly (MEA) and the nickel-metal foam flow fields. A revised system was analyzed with the reliability of the MEA and the Ni-foam set to 100%. After the revision, the components which contributed significantly to the system risk were the pumps. Simulations were run for several alternative systems to provide feedback on risk management suggestions. The risk engineering process developed with the design approach for this research is applicable to any system and it accommodates the use of many different risk engineering tools.Item A prediction of meander migration based on large-scale flume tests in clay(2009-05-15) Park, NamgyuMeander migration is a complex and dynamic process of the lateral movement of a river due to erosion on one bank and deposition on the opposite bank. As a result, the channel migrates in a lateral direction, which might be a major concern for the safety of bridges during their life span of 75 years. Although there are several existing models for predicting meander migration of a river, none of them are based on the physical model tests on a specific type of soil. A total of eight flume tests are conducted to develop a prediction equation of meander migration in clay. The test results of migration rate follow a hyperbolic function, and spatial distribution of the maximum migration distance is fitted with the Pearson IV function. The proposed equations of the initial migration rate and the maximum migration distance, obtained by a multiple regression technique, are validated with the laboratory data. A new methodology for risk analysis is developed to process a number of predicted channel locations based on each future hydrograph generated in such a way that all the hydrographs have the same probability of occurrence. As the output from risk analysis, a CDF map is created for a whole river representing a general trend of migration movement along with the probability associated with new location of the river. In addition, a separate screen is generated with a CDF plot for a given bridge direction so that bridge engineers can read a specific migration distance along the bridge corresponding to the target risk level (e.g. 1 %). The newly developed components through this research are incorporated with the other components in the MEANDER program which is a stand-alone program and the final outcome of the research team. Verification study of the MEANDER program is conducted with full-scale field data at the Brazos River at SH 105, Texas. The prediction results matched quite well with the measured field data. However, a more extensive verification study for other sites is highly recommended.Item Assessment of the effectiveness of the advanced programmatic risk analysis and management model (apram) as a decision support tool for construction projects(Texas A&M University, 2007-09-17) Imbeah, William Kweku AnsahConstruction projects are complicated and fraught with so many risks that many projects are unable to meet pre-defined project objectives. Managers of construction projects require decision support tools that can be used to identify, analyze and implement measures that can mitigate the effects of project risks. Several risk analysis techniques have been developed over the years to enable construction project managers to make useful decisions that can improve the chances of project success. These risk analysis techniques however fail to simultaneously address risks relating to cost, schedule and quality. Also, construction projects may have scarce resources and construction managers still bear the responsibility of ensuring that project goals are met. Certain projects require trade-offs between technical and managerial risks and managers need tools that can help them do this. This thesis evaluates the usefulness of the Advanced Programmatic Risk Analysis and Management Model (APRAM) as a decision support tool for managing construction projects. The development of a visitor center in Midland, Texas was used as a case study for this research. The case study involved the implementation of APRAM during the concept phase of project development to determine the best construction system that can minimize the expected cost of failure. A risk analysis performed using a more standard approach yielded an expected cost of failure that is almost eight times the expected cost of failure yielded by APRAM. This study concludes that APRAM is a risk analysis technique that can minimize the expected costs of failure by integrating project risks of time, budget and quality through the allocation of resources. APRAM can also be useful for making construction management decisions. All identified component or material configurations for each alternative system however, should be analyzed instead of analyzing only the lowest cost alternative for each system as proposed by the original APRAM model. In addition, it is not possible to use decision trees to determine the optimal allocation of management reserves that would mitigate managerial problems during construction projects. Furthermore, APRAM does not address the issue of safety during construction and assumes all identifiable risks can be handled with money.Item Developmental of a Vapor Cloud Explosion Risk Analysis Tool Using Exceedance Methodology(2012-10-19) Alghamdi, SalemIn development projects, designers should take into consideration the possibility of a vapor cloud explosion in the siting and design of a process plant from day one. The most important decisions pertinent to the location of different process areas, separation between different areas, location of occupied buildings and overall layout may be made at the conceptual stage of the project. During the detailed design engineering stage the final calculation of gas explosion loads is an important activity. However, decisions related to the layout and location of occupied buildings at this stage could be very costly. Therefore, at the conceptual phase of the development project for a hydrocarbon facility, it would be helpful to get a picture of possible vapor cloud explosion loads to be used in studying various options. This thesis presents the analytical parameters that are used in vapor cloud explosion risk analysis. It proposes a model structure for the analysis of vapor cloud explosion risks to buildings based on exceedance methodology. This methodology was developed in a computer program which is used to support this thesis. The proposed model considers all possible gas release scenarios through the use of the Monte Carlo simulation. The risk of vapor cloud explosions can be displayed using exceedance curves. The resulting model provides a predictive tool for vapor cloud explosion problems at the early stages of development projects, particularly in siting occupied buildings in onshore hydrocarbon facilities. It can also be used as a quick analytical tool for investigating various aspects of vapor cloud explosions. This model has been applied to a case study, a debutanizer process unit. The model was used to explore the different alternatives of locating a building near the facility. The results from the model were compared to the results of other existing software to determine the model validity. The results show that the model can effectively examine the risk of vapor cloud explosions.Item Location of an agribusiness enterprise with respect to economic viability: a risk analysis(Texas A&M University, 2006-04-12) Lau, Michael H.This study analyzes the economic and geographic effects of alternative locations on risky investment decisions in a probabilistic framework. Historically, alternative locations for multi-million dollar investments are often evaluated with deterministic models that rely on expected values or best case/worst case scenarios. Stochastic simulation was used to estimate the probability distribution for select key output variables, including net present value (NPV), of a proposed biomass to ethanol production facility in three alternative regions in Texas. The simulated NPV probability distributions were compared using Stochastic Efficiency with Respect to a Function (SERF) to predict the location preference of decision makers with alternative levels of risk aversion. Risk associated with input availability and costs were analyzed for the proposed plant locations so each location resulted in different levels of economic viability and risk that would not have been observed with a traditional deterministic analysis. For all analyzed scenarios, the projected financial feasibility results show a positive NPV over the 16 year planning horizon with a small probability of being negative. The SERF results indicate the Central Region of Texas is preferred for risk averse decision makers compared to the Panhandle and Coastal Bend Regions. Risk premiums were calculated for the alternative locations and are consistent for all risk averse decision makers, indicating the ranking of alternative locations are robust. Positive community impacts and sensitivity elasticities for key variables were estimated in the model. The estimated positive economic gains for the local economy are quite large and indicate locating a production facility in the region could substantially impact the local economy. The calculated sensitivity elasticities show ethanol price, ethanol yield, and hydrogen price are the three variables that have the greatest affect on the feasibility of a biomass to ethanol production facility.Item Technical, economic and risk analysis of multilateral wells(2009-05-15) Arcos Rueda, Dulce MariaThe oil and gas industry, more than at any time in the past, is highly affected by technological advancements, new products, drilling and completion techniques, capital expenditures (CAPEX), operating expenditures (OPEX), risk/uncertainty, and geopolitics. Therefore, to make a decision in the upstream business, projects require a thorough understanding of the factors and conditions affecting them in order to systematically analyze, evaluate and select the best choice among all possible alternatives. The objective of this study is to develop a methodology to assist engineers in the decision making process of maximizing access to reserves. The process encompasses technical, economic and risk analysis of various alternatives in the completion of a well (vertical, horizontal or multilateral) by using a well performance model for technical evaluation and a deterministic analysis for economic and risk assessment. In the technical analysis of the decision making process, the flow rate for a defined reservoir is estimated by using a pseudo-steady state flow regime assumption. The economic analysis departs from the utilization of the flow rate data which assumes a certain pressure decline. The financial cash flow (FCF) is generated for the purpose of measuring the economic worth of investment proposals. A deterministic decision tree is then used to represent the risks inherent due to geological uncertainty, reservoir engineering, drilling, and completion for a particular well. The net present value (NPV) is utilized as the base economic indicator. By selecting a type of well that maximizes the expected monetary value (EMV) in a decision tree, we can make the best decision based on a thorough understanding of the prospect. The method introduced in this study emphasizes the importance of a multi-discipline concept in drilling, completion and operation of multilateral wells.