Digital Commons Network^™

Multiphysics Modeling To Understand Microwave-Food Interactions In A Multi-Port Solid-State Microwave System., Kartik Verma

Masters Theses

Multiphysics modeling plays a crucial role in understanding the complexities of microwave-food interactions, especially in multi-port solid-state microwave systems where microwave parameters can be precisely and dynamically controlled. However, previous models using simplistic or manually measured oven geometries face challenges in accurately simulating the microwave heating process. This study first developed a robust 3-D scanning approach to capture precise geometric details of the oven cavity, incorporating them into multiphysics modeling for solid-state microwave heating. Furthermore, a quantitative validation approach was also developed to characterize modeling accuracy against experimental results. The results showed that multiphysics modeling with 3-D scanned geometry demonstrated …

Influence Of Physical Variability Of Highly Weathered Sedimentary Rock On Nitrate In Area 3 Of The Enigma Field Research Site At Y-12, Erin Kelly

Masters Theses

Uranium processing and waste storage in unlined waste ponds leached contaminants into the groundwater at Y-12, Oak Ridge, Tennessee, from the 1950s to 1980s. Groundwater wells near the S-3 ponds have had the highest nitrate concentrations of groundwater anywhere in the world (>10,000 mg/L). For reference, the maximum contaminant level for nitrate in drinking water set by the U.S. Environmental Protection Agency is 10 mg/L. Since 2012, the ENIGMA (Ecosystems and Networks Integrated with Genes and Molecular Assemblies) group has been characterizing, monitoring, and conducting field experiments to understand the interactions between contaminants, microbes, and the subsurface. The goals …

Rationalization Of Crystallographic Texture Evolution In High Gamma Prime Ni-Based Superalloys During Laser Powder Feed Directed Energy Disposition, Kevin Michael Smith

Masters Theses

Single-crystal nickel superalloy components are widely used in high temperature aerospace applications due to their excellent high temperature strength and creep resistance. Mechanical properties of single-crystal nickel superalloys are affected by chemical composition and the method of manufacture. Production of these components is costly and repair offers opportunity to sustain system performance while reducing costs. Additive Manufacturing by Laser Powder Feed Directed Energy Deposition (DED) is a promising method for repair due to selective application of material and the ability to tailor heat input. However, laser processing of these materials presents several challenges due to the high potential for cracking …

Study Of The Dynamic Behavior Of Molten-Salt Reactors, Vikram Singh

Masters Theses

Molten-Salt Reactors (MSR) are a Gen-IV reactor concept being investigated by companies and institutions alike. These reactors are considerably different from the current fleet of Light-Water Reactors and outside the experience base of most Nuclear Engineers. The fluid nature of the fuel leads to delayed temperature and reactivity feedback effects unique to each reactor design that need to be characterized to determine operability and safety limits. Moreover, the design space under consideration encompasses various fuel-cycles, neutron spectra, and materials. This requires a modeling methodology that can be applied to the breadth of designs under development and is the subject of …

Remote Characterization Of Physical Surface Characteristics Of Mars Using Diurnal Variations In Apparent Thermal Inertia, Cameron Blake Mccarty

Masters Theses

Analysis of the Martian surface today can provide insight into the processes that may have affected it over its history. Information about the physical surface characterization of a region can help determine the degree of sorting it has experienced and/or its geologic maturity. Sub-resolved “checkerboard” mixtures of materials with different horizontal thermal inertia mixtures can lead to differences in the apparent thermal inertia values inferred from night and day radiance observations. Standard methods for deriving thermal inertia from orbit via the THermal EMission Imaging System (THEMIS) can give values for the same location that vary by as much as 20% …

Spatial Variation In Fine Sediment And Microbial Transport Along Stream Cross Sections: Implications To Modeling And Monitoring, Thomas Michael Walton

Masters Theses

Spatial variations in suspended concentrations of fine sediment and indicator bacteria in streams is noted as a source of uncertainty in various applications of water quality datasets. Without proper analysis of the persistence and reasoning for this variance in natural systems, a finer resolution of model calibration is necessary to account for spatial variation in stream cross sections. This level of calibration has become of utmost importance due to technological advancements presenting the ability for water quality modeling frameworks to generate a much finer resolution of outputs. While the importance of model calibration has been noted for remediating levels of …

Bankfull Geomorphic Relationships And Hec-Ras Assessment In Small Catchments Of The Cumberland Plateau Ecoregion, Ryan Lee Hodges

Masters Theses

There is a great need for state governments to have effective watershed restoration and mitigation efforts to return degraded ecosystems to a stable, healthy condition. Given the growing investment in stream restoration efforts, there is an urgent need for tools to assess and improve the effectiveness of restoration efforts at local, state, and nationwide scales. In 2000 there was less than ten stream restoration permits provided by the state of Tennessee and has increased each year with almost forty permits issued in 2013. To better achieve successful stream restoration, appropriate channel designs must be used that reflect the hydraulic conditions …

Modeling Water Quality For Switchgrass Crop Production: Implications For Bioenergy Sustainability In East Tennessee, Zachariah Tzvi Seiden

Masters Theses

With passing of the US Energy Independence and Security Act (EISA) of 2007, there has been considerable research conducted on the sustainability of bioenergy crop production in the United States; switchgrass has shown particular potential for bioenergy production in East Tennessee. Many studies evaluating the environmental impact switchgrass has on runoff and water quality use the Soil and Water Assessment Tool (SWAT) for watershed modeling. Because SWAT is a lumped watershed model, it evaluates the result of hydrological processes for each hydrologic response unit (HRU), without accounting for the physical interactions between these HRUs. The Water Erosion Prediction Project (WEPP) …

Investigating Instabilities With Hec-Ras Unsteady Flow Modeling For Regulated Rivers At Low Flow Stages, Jennifer Kay Sharkey

Masters Theses

Dams are used throughout the United States for generation of electricity and flood control. The Tennessee River Valley’s regulated river system extends through Tennessee and parts of Kentucky, Mississippi, Alabama, Georgia, North Carolina, South Carolina, and Virginia. Of the dams in this area, 49 are managed by the Tennessee Valley Authority (TVA). The TVA forecasts and monitors the activities related to these dams and others in the area on an around-the-clock basis to ensure maximum generation potential is attained and to prevent flooding of the surrounding cities. To best forecast hydrology for the regulated river system, the TVA chose to …

Comparing Models Of Demographic Subpopulations, Jessica Jones Moehl

Masters Theses

Understanding specific multi-dimensional demographics of populations in the United States at high resolutions is made difficult by the restriction of data released by the Census Bureau because of privacy concerns. Efforts to model these subpopulations have been increasing in recent years. These modeled populations have applications in decision making at all levels of government as well as in academia and the private sector. Two models have shown promising techniques for incorporating multiple levels of data to model sub populations in a meaningful way. These models, the Copula Model by Kao et al. (2012) and the Penalized Maximum Entropy Model by …

Modeling Interventions In The Owned Cat Population In Knox County, Tn, Evan Pierce Lancaster

Masters Theses

The rapid growth of cat populations in many communities across the United States has resulted in overpopulation and an increase in euthanasia procedures. To combat these challenges, communities have instituted spay/neuter programs as a preventative strategy. In particular, Knox County, Tennessee, has developed and implemented a program, called the Spay Shuttle, which offers free spays and neuters for owned cats throughout the county.

We develop a discrete time, age-structured model of owned female cats in Knox County to investigate the effects of implementing extra spaying intervention strategies to the population over the course of 5 years. We determine that a …

Comparative Study On Posture And Its Influences On Horizontal Ground Reaction Forces Generated By Muscles: Implications For Crouch Gait, Hoa Xuan Hoang

Masters Theses

Crouch gait decreases walking efficiency due to the increased knee and hip flexion during the stance phase of gait. Crouch gait is generally considered to be disadvantageous for patients with cerebral palsy; however, a crouched posture may afford biomechanical advantages that lead some patients to adopt a crouch gait.

To investigate one possible advantage of crouch gait, a musculoskeletal model created in OpenSim was placed in 15 different postures from upright to severe crouch during initial, middle, and final stance of the gait cycle. A series of optimizations were performed for each posture to maximize ground reaction forces for the …