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Application of Hierarchical Bayes to Estimate Relative Risk of Suicide in Idaho Counties
No full textSuicide is the intention of harming oneself to cause death. Idaho is amongst the states with growing rates of suicide deaths and suicide is a major public health issue. Most studies conducted on suicide have investigated suicide rates at state levels but not small areas such as counties or demographic groups. This study was conducted to develop a reliable model to characterize suicide at the county level. \par Relative risk of suicide for all counties in Idaho were obtained using Poisson hierarchical Bayes model and the performance was compared to standardized mortality ratio estimates. Relative risk estimates obtained using Poisson hierarchical Bayes had low standard errors compared to the relative risk estimates obtained using standardized mortality ratio. These estimates allowed us to observe that age adjusted relative risk of suicide was consistently above that of the state of Idaho in Custer, Lemhi, Shoshone and Nez Perce. Also, Madison was the only county with age adjusted relative risk of suicide consistently below the state of Idaho over the time period. \par County level suicide risk factors such as unemployment, education and social connectivity could be incorporated into the model to predict relative risk of suicide. Local government and public health experts could use predictions from the model to target suicide preventive measures.masters, M.S., Statistical Sciences -- University of Idaho - College of Graduate Studies, 2020-0
Computational Modeling of Flow in a 10MWe Natural Convection Molten Salt Reactor
No full textThis research investigates the use of computational fluid dynamics (CFD) to simulate flow in a practical power system that includes a natural-convection molten salt reactor (MSR). Included herein are five sets of simulations, which start simply and build in complexity. Unique aspects of this research: • Each simulation explores realistic design aspects of practical MSRs; i.e., those used for electric power generation, etc. • Each simulation uses internal heat generation (instead of surface/external heat flux) to reflect energy released in the reactor vessel. • An actual fuel salt was used for three of the five simulation sets. It is based on a mixture of lithium & beryllium fluoride salt, known as FLiBe. • Simulations that use FLiBe as the working fluid include a newly developed relation – variable energy source/power density – for energy released in the reactor vessel. This unique approach is based on operational data from actual MSRs. It reflects changes in reactivity (and thus power density) as a function of salt temperature and thus captures the negative temperature coefficient effect. First is a series of 16 cases, using simple cylinders for the reactor and heat exchanger, with water as the working fluid. These determine the size, shape & elevation difference between the reactor vessel and heat exchanger. To achieve natural convection flow within a specified temperature range, the minimum relative elevation difference between the reactor and heat exchanger is 12 feet. CFD results in the range of interest match analytic values within 4.4%. Next is a series of 10 cases, using baffled cylinders for the reactor and heat exchanger, with FLiBe salt as the working fluid. These determine the elevation difference between the reactor vessel & heat exchanger. To achieve natural convection flow within a specified temperature range, the minimum relative elevation difference between the reactor and heat exchanger is also 12 feet. CFD results in the range of interest match analytic values within 0.55%. The third set is a benchmarking template for a test rig built at the University of Idaho campus in Idaho Falls. At the point of incipient natural convection flow, the temperature difference from the simulation is within 2.45% of the value predicted by analytic means. Next is simulation of a realistic MSR system. It includes a reactor vessel with complex internal structure, to model an array of graphite moderator bars. This confirms that a relative difference in elevation of 12 feet meets the design criteria for the specified temperature range. Finally, a simulation of a different realistic MSR system which uses an external reflector rather than internal moderator bars. The original design has a difference in elevation of 4 feet. Simulations show that this does not meet the design criteria of achieving the recommended temperature range. These results suggest that it is possible to simulate a realistic natural convection molten salt reactor. Using the techniques herein, one can obtain valuable engineering information to assist in the design of practical power systems.doctoral, Ph.D., Mechanical Engineering -- University of Idaho - College of Graduate Studies, 2020-0
One-pot Carbonyl Reduction and Carbonate Formation using Sodium Borohydride in Dialkyl Carbonate Solvents and the Development of Ionophore-inspired Monomers and Polymers for Ion Sensing
No full textThis dissertation describes two separate projects. First is a convenient synthetic method for the conversion of ketones and aldehydes to unsymmetrical carbonates in refluxing dialkyl carbonate solvents using sodium borohydride in a single step. This one-pot method utilizes “greener” carbonate solvents and eliminates the need for toxic alkyl chloroformate reagents. An extensive substrate scope and reaction optimization are presented. The second part describes the development of flexible and printable calcium ion-selective electrodes (ISEs) and the use of commercially available conductive CNT inks as the ion-to-electron transducer. These electrodes were evaluated potentiometrically with the aim of retaining sensitivity while also evaluating the surface impedance. We found that ionophores were compatible and equally selective when printed with conductive ink, yet the binding agents were not compatible and needed to be added separately following jet-printing. This led to the synthesis of a novel ionophore-inspired monomer and its polymerization both in various copolymer blends and in bulk on surfaces using activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP). The polymerization blends were used to explore the potential of replacing common binding agents found in solid contact ISEs with ionophore based binding agents. The ARGET ATRP polymer brushes were developed with the goal of growing the ion-sensing polymers directly onto carbon nanotubes (CNTs) as potential ion-sensing components to known CNT inks. Ultimately, it was found that the total average bond distances of the novel ionophore analog were within 0.5% difference of that of the known calcium ionophore ETH129, yet the stoichiometry differed. Overall, ionophore compatibility in jet-printing, sensing, and the monomer as a potential polymer candidate for device design were explored.doctoral, Ph.D., Chemistry -- University of Idaho - College of Graduate Studies, 2020-1
Sustainability Across Diverse Engineering Disciplines (Geothermal Technology, District Cooling Systems, Acid Mine Drainage, and Additive Manufacturing)
No full textSustainability is a broad term that considers environmental aspects in any products/processes design, fabrication, application, and end of life. This thesis is an application of sustainability across multiple disciplines including power generation, district heating and cooling, mining, and additive manufacturing. Geothermal sources as a sustainable source of energy is often an underutilized resource that has potential to offset fossil fuel sources of energy such as coal and natural gas, while still providing stable baseload power. Various methods of performance improvement, as well as integration of geothermal technology with other renewable energy sources were also discussed. The environmental impact and economic viability of the technology were mapped as well. The advantages and disadvantages of the technology and opportunities for improvement were explored based on the recent studies. Briefly, the potential role of geothermal technology in a sustainable future was discussed. Applying exergy analysis on the district cooling in the University of Idaho, Moscow campus prioritized the exergy loss. By using TRNSYS modeling and simulation based on a modified thermal energy storage operation condition the new operation schedule for the cooling system in University of Idaho Moscow campus yielded a potential cost savings of $140,000 annually while eliminating 428,800 kg of CO2 emissions and improving the sustainability. Acid mine drainage and its dangerous effects are one of the greatest challenges currently facing humanity. With sustainability approach to that issue, implementation of active and passive treatment, in conjunction with collaborative relationships between government, academia, investors, and industry were suggested to solve this crisis. Furthermore, governments must continue to enforce policy and regulations that ensure the burden of remediation rests upon those who caused the damages. Metal additive manufacturing offers a revolutionary way to manufacture parts and components. The different type of the additive manufacturing, financial and environmental benefits, and advantages and disadvantages were studied through literature review. Through Life Cycle Analysis, a method of metal additive manufacturing (Laser Metal Deposition) and a casting manufacturing method were compared for the manufacturing of a stainless-steel pump impeller. It was concluded that additive manufacturing was a sustainable method of manufacturing components in compare with conventional method. The four chapters combine to describe and analyze sustainability across multiple disciplines. Factors such as policy, society, economy, design limitations, performance, and efficiency have been shown to affect the sustainability of these technologies. This thesis addresses these factors and describes how improvements ranging from small to monumental within these disciplines can affect positive change in the present and future society.masters, M.S., Mechanical Engineering -- University of Idaho - College of Graduate Studies, 2020-0
School Travel Data Collection: Comparing the Use of Quadcopter Drones with Travel Tally Surveys
No full textTravel tally surveys are administered by elementary, middle, and high (K-12) schools to collect data that measure how students arrive and leave school each day. This data can be used to determine both transportation safety and mobility needs. Collecting this data is usually accomplished by asking teachers to collect a tally in their classrooms; the data are then compiled to determine a representative result for each school. This process requires advanced planning from school administrators and teachers to ensure that information gathering is coordinated and relies on the personal input of each student. Since the age of elementary school students may be as little as six or seven years old, this approach may not always be reliable.In this study, a new method using a quadcopter drone was examined. For comparison purposes, participatory student tally surveys and drone videos were collected on the same day at three different elementary school sites, and the results and effectiveness of each counting method were compared and analyzed. The study concluded that the survey and drone results did not always yield similar results for all modes, so an explanation as to why these deviations occurred and what it means for researchers and practitioners is discussed. Given that drone technology continues to evolve, the lessons learned from this study can be applied toward future school transportation and other mobility studies.masters, M.S., Civil Engineering -- University of Idaho - College of Graduate Studies, 2020-1
Gravitational Influences on Ground Dominance in Control of Egospeed
No full textHuman perception of speed is heavily influenced by their distance from a ground plane. Previous studies have found that while controlling speed during simulated flight through an environment with both a ground plane and a plane of clouds above, humans naturally attend to speed information present in the ground plane only (Meyer, 2015). Potential factors leading to attentional selection of the ground plane under standard viewing conditions, known as ground dominance, include the direction of gravity, lower visual field bias, and the location of limbs (Dyre, Meyer, & Adamic, 2013). This experiment decoupled the direction of gravity from visual field and limb location by manipulating the posture of participants as either upright or supine. We continued to find evidence of altitude-speed cross-talk (confusing changes in altitude as changes in speed) in both the upright and supine conditions, providing evidence that gravity alone is not a determining factor on ground dominance.masters, M.S., Psychology -- University of Idaho - College of Graduate Studies, 2020-0
Identification and Control of Industrial Gas Fired Heat Treatment Batch Furnaces
No full textThis thesis presents methods of system identification and frequency domain control for industrial heat treatment gas powered box furnaces with an emphasis on conforming with \ac{tus} requirements. While the findings are generically applicable to gas powered heat treatment furnaces information from a specific furnace was used as a source of data and model validation. Two methods of system identification are explored. First is an output error method using production setpoint/output data, and the second is a model derived from thermodynamic principles and furnace geometry. Control systems for each model are designed, and analyzed with respect to temporal performance and global stability.masters, M.S., Electrical and Computer Engineering -- University of Idaho - College of Graduate Studies, 2020-1
Characterization and Modeling of Irradiation Induced Nanoclusters in Ferritic-Martensitic and Zirconium-Niobium Alloys.
No full textThe objective of this dissertation is to characterize, and model irradiation-induced solute clustering in commercially ferritic-martensitic alloys (T91, HCM12A, and HT9) and Zr-1 % Nb alloys following ions or neutron irradiations and also to prescribe the required temperature shift for ion irradiations to emulate neutron irradiation. Ferritic-martensitic alloys are irradiated with Fe2+ or neutrons to a dose of 3 dpa at 500 °C and 370 °C while Zr- 1 %Nb alloy is irradiated with Kr2+ or neutrons irradiated to 5 dpa at 310 °C. Irradiation induced segregation and nanocluster morphology are analyzed using atom probe tomography. The size and number density in each F/M alloys differ with ions or neutron irradiation while the morphology of Nb-rich nanoclusters following Krypton irradiation is comparable to that seen after neutron irradiation. Two distinct models (Cluster dynamic and NHM model) are utilized to simulate nanocluster evolution in F/M alloys and they both predicted a negative temperature shift will be needed for ion irradiation to emulate neutron irradiation damage.doctoral, Ph.D., Materials Science -- University of Idaho - College of Graduate Studies, 2020-1
Modeling and Experimental Validation of Latent Heat Thermal Energy Storage System
No full textIn an effort to address the detrimental effects of climate change, a paradigm shift has taken place over the last couple of decades to switch from fossil fuel-based energy sources to clean energy. This change, along with the ever growing need for energy has facilitated the increasing penetration of renewable energy sources such as wind, solar, and hydropower. Although renewable energy can indisputably minimize the threat of global warming, their dependency on weather conditions and diurnal variations leads to inconsistencies in energy supply. To overcome this intermittency, these clean energy sources are quite often backed-up by fossil-fuel generators, thus defeating the purpose of clean energy establishment. In order for renewable energy sources to become completely reliable as a primary source of energy, it should be stored during hours of excess production and be ready to use during periods of excess demand. This can be achieved by incorporating energy storage systems. Currently, thermal energy storage (TES) is the only technology to be deployed on a gigawatt scale, and specifically the sensible heat TES. This technology is expensive and in some cases, intrinsically consumes energy to prevent the storage medium from freezing. In comparison, latent heat storage designs could theoretically offer higher gravimetric storage capacities, resulting in smaller storage sizes. However, low thermal conductivities of phase change materials hinders the realization of this technology's potential, thereby preventing large scale deployment. To overcome this issue, several modifications to the TES designs have been undertaken. Regardless, the models developed so far are high-fidelity and high-complexity, design specific, and therefore computationally expensive. To evaluate the benefits of coupling latent heat TES systems, integrated systems-level analyses need to be carried out. This requires simpler, yet, accurate models. In this dissertation, simplified, transient, validated models are developed for a latent heat thermal energy storage system. The modeling effort includes the analysis of three models, comparison of these models to a commercial CFD tool, and verification and validation using results acquired by performing experiments on a bench-scale latent heat thermal battery. To enhance heat transfer and overcome the underlying deficiency of PCMs, finned tube design is used. Preliminary analysis is conducted by assuming pure conduction within the phase change material, however, this is modified to accommodate for natural convection, by deriving an apparent thermal conductivity for the liquid phase. This apparent thermal conductivity is based on a correlation that includes the Rayleigh number, along with coefficients that are acquired empirically by trial and error method. The coefficients C and n for the geometry considered in this study are 0.228 and 0.25, respectively. To account for the presence of fins, a novel approach based on the thermal resistance network is applied to derive an effective thermal conductivity. The combination of this effective thermal conductivity and the apparent thermal conductivity, is applied to the liquid domain to model phase change in a finned tube system, that experiences a combined, natural convection- and conduction-based heat transfer.doctoral, Ph.D., Nuclear Engineering -- University of Idaho - College of Graduate Studies, 2020-1