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Characterizing the Mechanical Properties of a Commercial No-Filler Laser Weld in a 304 Stainless Steel Alloy
No full textThe mechanical properties of a commercially laser-welded 304 alloy were studied. A sample of thewelded material and a sample of the unwelded material were tensile tested to find that the welded sample allowed more ductility while maintaining the same ultimate tensile strength as the unwelded sample. Optical and scanning electron microscopy showed that the weld contained smaller average grain sizes than the surrounding metal. The weld was found by nanoindentation to have a higher hardness than the surrounding metal before the tensile test. Due to the tensile test, the weld experienced lower strain than the surrounding metal, as found by nanoindentation and x-ray diffraction. This information was used to approximate the mechanical properties of the weld and applied to a finite element analysis to corroborate the results with the tensile test data. The approximated strain response of the weld was also compared to a strain hardening model.masters, M.S., Mechanical Engineering -- University of Idaho - College of Graduate Studies, 2023-0
Deep Learning for Ultrasound-based Breast Cancer Early Detection
No full textBreast cancer is a pervasive health issue that affects millions of women worldwide. Early detection of breast cancer is crucial for reducing mortality rates and improving patient prognosis. By identifying cancer at an early stage, treatment options can be initiated promptly, leading to more successful outcomes. Breast ultrasound imaging is a valuable tool in the early detection of breast cancer. It offers several advantages, including painless and noninvasive imaging, absence of ionizing radiation, and affordability. Ultrasound imaging provides detailed visualization of breast tissue, allowing healthcare professionals to identify suspicious lesions, and assess tumor characteristics. Moreover, it is particularly effective in evaluating dense breast tissue, which may pose challenges for other modalities such as mammography. Despite its advantages, the interpretation of breast ultrasound images presents certain challenges. One of the major difficulties is the presence of speckle noise, which can obscure subtle abnormalities and make accurate tumor identification challenging. Additionally, variations in image quality, tumor shapes, and sizes further complicate the analysis. Computer-aided diagnosis (CAD) systems have emerged as crucial tools in breast cancer detection and diagnosis. These systems employ sophisticated algorithms and deep learning techniques to assist healthcare professionals in analyzing breast ultrasound images. CAD systems can aid in tumor segmentation, feature extraction, and quantification, thereby enhancing diagnostic accuracy and efficiency. By leveraging the power of artificial intelligence, CAD systems can assist in early cancer detection, reduce false-positive rates, and improve overall patient care.In this dissertation, I built several deep learning approaches to enhance breast cancer early detection using ultrasound image. First, I proposed two novel deep learning approaches, STAN and ESTAN, to detecting and segment small breast tumors. STAN addresses the challenges posed by speckle noise, poor image quality, and variable tumor shapes and sizes in breast ultrasound images. A multiscale feature extraction architecture was proposed to learn and fuse context information at different scales. ESTAN introduces a further improvement to the segmentation of small tumors in breast ultrasound images. Building upon the STAN network, the ESTAN model incorporates additional enhancements to address the aforementioned challenges. The model designed a novel architecture by incorporating breast anatomy to the design of the deep learning model. Second, I built a benchmark for breast ultrasound image classification. This study introduces a divers benchmark dataset and evaluation framework specifically designed for breast ultrasound image classification. In addition, we proposed a comprehensive evaluation methodology that incorporates multiple performance metrics and compares the effectiveness of different classification algorithms. The benchmark dataset and evaluation framework serve as valuable resources for researchers and practitioners, facilitating the development and assessment of robust classification models. In addition, we proposed a novel multitask learning approach to perform breast ultrasound image classification and segmentation simultaneously. Finally, I proposed a hybrid multitask CNN-Transformer network for breast ultrasound tumor Classification. The proposed approach combines the strengths of convolutional neural networks (CNNs) and transformer networks to capture both local and global information effectively. The network is trained using a multitask learning framework, simultaneously performing tumor classification and segmentation.doctoral, Ph.D., Computer Science -- University of Idaho - College of Graduate Studies, 2023-0
Advancements in the Evaluation of Heterogeneity for Nuclear Criticality Safety in High-Assay Low-Enriched Uranium Systems
No full textA review of historical nuclear criticality accidents and critical experiments is conducted to evaluate the effects of heterogeneity in uranium-water critical systems. Advanced modeling methods are developed and described which generate and evaluate data to determine correlated effects between heterogeneity and other nuclear parameters. The described methods are validated against existing historical data using statistical methods.doctoral, Ph.D., Nuclear Engr & Industrial Mgmt -- University of Idaho - College of Graduate Studies, 2023-0
Measuring Intake and Behavioral Responses to Phenylthiocarbamide for the Identification of Phenotypic Expression of Bitter Tasting Ability in Sheep
No full textResearch on the genetic and phenotypic expression of bitter taste perception in sheep suggests bitter-tolerant sheep may be more inclined to consume less palatable rangeland plants. In the absence of definitive genetic tests, the current work focuses on the development of accurate and precise methods for the classifying of bitter-taste-sensing phenotypes (i.e., bitter taster) in sheep. Existing methods for determining bitter taster status of sheep using phenylthiocarbamide (PTC)-spiked drinking water were lengthy, laborious, and limited on sample size. Our first experiment outlines refined methodology for the classification of nearly three times the number of rams, utilizing only two concentrations of PTC-solution over a 2-day test period. During this trial, behavioral reactions uniquely associated with each PTC-tasting phenotype were also identified. A later attempt to develop methods utilizing an involuntary drench to deliver PTC-solution suggests that the use of behavioral analysis for the identification of bitter tasting phenotypes in sheep may be limited to voluntary preference tests. Although bitter taster status impacts dietary preference in humans, literature regarding the influence of bitter taste perception on the foraging behavior of sheep is limited. Subsequent tests using intake of both internal and topical applications of PTC-treated feed to identify bitter tasting ability were inconclusive. While some mature rams showed reluctance to consume PTC-treated feed, ram lambs consumed PTC pellets to near entirety. Although ram lambs did not demonstrate an aversive feed intake response, behavioral reactions indicative of bitter sensitivity were observed among individual sheep. Factors outside of genetics, such as physiological state or learned behaviors may play an important role in voluntary diet decision making in sheep. Efficient methods for the identification of bitter taster phenotypes are the first step in determining the effects of bitter tasting ability on dietary selection in sheep.doctoral, Ph.D., Animal, Vet & Food Sciences -- University of Idaho - College of Graduate Studies, 2023-0
Life Cycle Assessment of Carbon Capture Membrane Separation Technologies
No full textCarbon capture has been a significant topic due to elevating carbon dioxide (CO2) levels in the atmosphere. CO2 in the atmosphere is above 420 parts per million (ppm) as of 2022, 70 ppm higher than it was 50 years ago. Carbon capture technologies (CCUs) are being heavily researched to tackle this problem. Researchers have been focusing on developing processes that can capture carbon dioxide from existing sources and utilize it to produce commercial products such as methanol, ethanol, fuels, etc. However, not all these processes may be environmentally feasible, as it has been established that some of these processes end up doing more harm to the environment. Capture technologies such as solvent-based, adsorption-based, cryogenic distillation, and pressure-swing adsorption are currently being researched, but are associated with higher costs and have historically been unsustainable. Membrane-based carbon capture technologies are considered economical and environmentally friendly alternatives. Idaho National Laboratory (INL) researchers have been developing new types of membranes for the last 30 years, one of them being polyphosphazene polymer membranes, specifically Poly[bis((2-methoxyethoxy)ethoxy)phosphazene] (MEEP), which has demonstrated the highest selectivity for CO2 over nitrogen (N2). Life cycle analysis (LCA) has become a crucial step in evaluating carbon capture processes for their suitability to be utilized on a small and large scale. An extensive life cycle assessment (LCA) was performed to determine the environmental feasibility of the entire life cycle of the MEEP polymer material compared to other CO2-selective membranes and separation processes. The MEEP-based membrane processes have been shown to produce at least 42% less equivalent CO2 emissions than Pebax-based membrane processes. Similarly, MEEP-based membrane processes produce 34–72% less CO2 than commercial separation processes. In all studied categories, MEEP-based membranes report lower emissions than Pebax-based membranes and commercial separation processes.masters, M.S., Chemical & Biological Engineering -- University of Idaho - College of Graduate Studies, 2023-0
Estimation of Dairy Manure-based Nutrient Supply-Demand Balances in Idaho, 1990 to 2022
No full textThe dairy industry in Idaho (ID) has expanded rapidly in the past 30 years. The expansion of the dairy industry has brought nutritious food and drinks across the U.S. and world and substantial agribusiness opportunities, especially in Southern ID. The dairy is, as of 2023, the largest industry regarding cash receipts in the ID agricultural economy. Development of the dairy sector has not only increased revenues for the direct participants in the dairy supply chain, but also aligned sectors such as production of feed crops, including alfalfa hay and corn silage. Despite these benefits, the dairy industry also produces substantial amounts of dairy manure, and management of dairy manure is a considerable cost for dairy producers. Manure contains large amounts of nutrients, but the local demand for crops may not be able to absorb all of the supply, especially in major dairy producing regions in Southern ID. In addition, the increase in population and associated increase in land conversion for housing and other commercial development in some regions of ID in recent decades has led to reductions in cropland areas for feed and other crops, which has provided fewer outlets for distributing manure-based nutrients. The associated potential decrease in nutrient demand from cropland can intensify the oversupply of nutrients in some regions. An oversupply of manure can cause nutrients to accumulate in the local environment, which can contaminate soil, water, and air greenhouse gases. While the nutrient oversupply can be detrimental to the local environment, the extent of the impact regarding the total quantity and distribution of manure-based nutrients remains unclear. In this thesis, dairy manure nutrient supply-demand balances in ID were quantified for the observation period of 1990 – 2022. The first set of quantification analyses is done at the state, region, and county-levels to determine the regional distribution of dairy manure in the state. A second analysis, which focuses on the more localized distribution of dairy manure and cropland, relies on a unique dataset from the Idaho State Department of Agriculture that allows for determination of the locations, sizes, and dates of establishment of ID dairies. In this more spatially targeted analysis, supply-demand balances were estimated at the census tract level for three major dairy producing counties in Southcentral ID (Gooding, Jerome, and Twin Falls) for the period of 2007 to 2022. The results from the quantification analysis show that the state-level supply-demand balance has increased rapidly for all analyzed nutrients over the course of 1990 to 2022. In addition, the increase in nutrient balance has mainly occurred in Southcentral and Southwest ID, where most of the dairy farms have been established over this observation period. The spatial analysis demonstrates that the most acute increase in the manure-based nutrient supply has concentrated near rivers, including the Snake River, to a relatively higher degree than other census tracts. As time has passed, the number of dairies, and associated manure-based nutrients, further away from the Snake River has also increased. This has led to a substantial accumulation of nutrients in some areas that had previously not had much manure present. In some census tracts, as of 2022, the amount of nutrient accumulation was estimated at 10 times larger than in 2007. However, years of substantial amount of nutrient accumulation, and corresponding reduction in pace of dairy industry expansion, has caused nutrient accumulation to increase at a decreasing rate in more recent periods. Due to the chemical characteristics of liquid and solid manure, there has been greater increases in supply and accumulation of Nitrogen than Phosphorus and Potassium. Composting decreases Nitrogen relative to Phosphorus and Potassium, and dairies and industry partners currently compost about half of the dairy manure in Southern ID. The main result of this thesis is that the substantial expansion of the dairy industry has led to a large accumulation of dairy manure nutrients in Southern ID. Further development of manure-based fertilizer product industries, which can implement value-added processes that extract the water and concentrate nutrient solids from liquid and solid dairy manure, and, hence, reduce the transportation costs to ship the manure-based nutrients away from the dairies, can help reduce the nutrient oversupply in the future. Such development can also potentially facilitate shipment of manure-based fertilizer across the Western U.S., helping both dairies via a diversified revenue stream as well as specialized manure processing businesses to generate profits from related businesses. This can also help remediate environmental issues, including reducing contamination of soil, water, and air and release of greenhouse gases. Reducing the environmental impact of the dairy industry can both ensure that agricultural productivity is sustained and help ensure that the ID agricultural economy remains vibrant in the future.masters, M.S., Agricultural Economics & Rural Soc -- University of Idaho - College of Graduate Studies, 2023-0
A Hydrologic and Geochemical Investigation of Basin Infiltrated River Water in Alluvial, Basalt, and Combination Alluvial/Basalt Aquifers
No full textGroundwater overdraft is a persistent problem in the western US including in the East Snake River Plain (ESRP) Aquifer (ESRPA), the largest in Idaho. Managed aquifer recharge (MAR) is a tool increasingly utilized for stabilizing aquifer storage volumes and is employed across the ESRP to infiltrate untreated river water through constructed recharge basins. Hydrologic and water quality data from monitoring well networks in the vicinity of three ESRP MAR basins – one each in an alluvial, basalt, and combination alluvial/basalt setting, together representative of the ESRPA – were examined. Processes investigated were hydrologic mixing between ambient groundwater and infiltrated water and whether cation exchange and calcite precipitation/dissolution reactions impacted MAR water. In addition, groundwater level increases and decreases in response to infiltration events were investigated as to whether they indicated the arrival and departure of MAR water at a pumping location. The results also provide suggestions regarding the location of hydrologic and chemical monitor well placement as MAR programs continue to evaluate new sites. A sample analysis provided results consistent with the stratification of infiltrated and ambient groundwater at all three sites. In the alluvial and basalt settings some sampling locations were entirely infiltrated water while at the combination alluvium/basalt setting vertical stratification in the aquifer was inferred. Hydrologic responses to basin inflow events in wells chemically unimpacted by MAR water indicated that water table responses did not necessarily evidence the arrival or departure of infiltrated water but could be the result of a “mound” of infiltrated water growing under the basins that displaced ambient groundwater away from it. At the alluvial site an analysis of samples indicated that reverse cation exchange impacted infiltrated water, but calcite precipitation (if it occurred) did not impact infiltrated water chemistry. Geochemical modeling predicted that the reverse cation exchange processes would continue with increased alluvium interaction, but that calcite precipitation would have a nondetectable impact on the chemistry of infiltrated water and in any case would not be discernable from an analysis of the samples because much of the calcium precipitated as calcite would have been derived from reverse cation exchange. All wells, located between 620 ft (190 m) downgradient and 100 ft (30 m) cross gradient, were chemically impacted by infiltrated water (primary infiltration event average of 24.8 AF [30,590 m3] per day for 54 days) suggesting that these are appropriate distances for chemical monitor wells. However, local heterogeneities in the flow field played a larger role in the movement of infiltrated water than simple distance from the basin. At the basalt site, fracture flow governed hydrologic and chemical impacts. Two distant (greater than 5,280 ft [1,609 m]) locations showed no chemical interactions between the aquifer matrix and infiltrated water. At a third location cation exchange processes may have impacted the samples. The three wells chemically impacted by infiltrated water were within 600 ft (183 m) of the basin while the other locations, 5,280 ft (1,609 m) or greater, were hydrologically impacted but showed no evidence of infiltrated water possibly because preferential flow paths routed the high volumes (primary infiltration event average of 730 AF [900,440 m3] per day for 133 days) away from the wells. Together these results suggest a range in which chemical monitor wells might be located but also demonstrate the significance of flow field heterogeneity. At the combination alluvium/basalt site, wells were located 1,250 ft (380 m) cross gradient and 6,750 ft (2,060 m) downgradient and were not chemically impacted by the basin (infiltration event average of 88.3 AF [180,900 m3] per day for 136 days) suggesting that these locations are too distant to be appropriate for chemical monitoring. Hydrologic responses to infiltration events were observed only in the closer location.masters, M.S., Geography & Geological Science -- University of Idaho - College of Graduate Studies, 2023-0
Techniques for Enhancing Compiler Error Messages
No full textBottom-up parsing technology advanced and efficiently automated static analysis of source code but raised the challenge of maintaining understandable communication between compilers and humans. Reporting errors in the source code in a human-understandable language is essential for the efficiency of the software development process, especially for students learning programming. This research improves compiler error messages for students in introductory programming courses at the college level. This study of compiler error messages is written from the compiler writer's perspective. Analysis of hundreds of erroneous programs in different parsing states led to designing 3-phase parsing techniques that overcome some of the limitations of LR parsers in reporting friendly error messages. 3-phase parsing prioritizes the parsing of the large code components over diving into all the details. The first phase parses the functional structures and ignores errors in the syntax of the smaller constructions. The second phase parses the control structures and ignores errors in the expressions and other statements. The third phase parses the expressions and statements excluded from phase two. The design gives more control over when and from which grammar rules to report errors first. The design minimizes the number of states in the parser automaton since each phase parses a subset of the language grammar. We evaluated the new design with a human-subject control experiment. The experiment compares the quality of syntax error messages of an educationally customized compiler EduCC with error messages produced by GNU GCC and Microsoft Visual C++. EduCC implements the 3-phase parsing techniques for a subset of C++ language. The participants were 53 Computer Science and Engineering students at the New Mexico Institute of Mining and Technology. In a within-group experiment design, the participants had to find errors and fix erroneous C++ programs. The experiment shows that 3-phase parsing techniques improved the quality of syntax error messages.doctoral, Ph.D., Computer Science -- University of Idaho - College of Graduate Studies, 2023-0
An All-Optical 4-Bit Adder Composed of Fabry-Perot Devices
No full textThis work models an all-optical 4-bit adder comprised of Fabry-Perot devices. Each device is composed of 2 silver mirrors on either side of a cavity made of a nonlinear Kerr material. These devices are optically bistable and suitable for fast logic operations on the order of picoseconds. An amplifying buffer is used between devices to adjust the transmitted signal’s amplitude to the desired value, and to provide control for logic operations. This work uses the method of finite-difference time-domain (FDTD) in one-dimensional (1D) space to demonstrate the feasibility of the proposed idea.doctoral, Ph.D., Electrical and Computer Engineering -- University of Idaho - College of Graduate Studies, 2023-0
Leachate Experiments to Evaluate Weathering of Waste Rock for Backfill Aquifers in Restored Open Coal Mine Pits, Powder River Basin, USA
No full textOpen-pit mining companies utilize waste rock for landscape restoration which may include the construction of backfill aquifers. Chemical weathering and contaminant transport can be altered in backfill aquifers because of the mining of the waste rock that produces newly available mineral surfaces and nanoparticles that can impact water quality. Waste rock from the Cordero Rojo open-pit coal mine in the Powder River Basin was exposed to benchtop weathering experiments for 20 weeks at temperatures of 5 °C and 20 °C. Leach columns containing 4 kg of waste rock were saturated and drained twice weekly. Collected leachate was analyzed for Eh, pH, alkalinity, specific conductance, and cation and anion concentrations as unfiltered and 0.45-μm and 0.2-μm filtered concentrations. During the experiment, leachate Eh and pH substantially varied during the first 50 days, which corresponds to a period of high specific conductance and alkalinity values. Correspondingly, anion and cation concentrations were the largest during this early weathering stage and the filter fractions indicated multiple weathering processes, such as particle transport, salt dissolution, and sulfide oxidation. After this early weathering stage, all environmental parameters slowly evolved towards a chemical equilibrium of neutral, oxidizing, and low solute conditions. This evolution was reflected in the decline and stabilization or non-detection of metal(loid) concentrations reflective of a shift to primarily bulk aluminosilicate weathering. Over the course of the experiment, the solute trend of certain elements indicated particular weathering processes— cadmium and nanoparticle transport, selenium and salt dissolution, and arsenic and the oxidation of pyrite. Elements that are found in multiple sources, such as iron, indicated multiple weathering processes that occurred in the early weathering stage and throughout the experiment. The mining of the overburden formations created newly available mineral surfaces and nanoparticles that could release elements into solution that were not expected to be present given historical aquifer water quality for the overburden formations.masters, M.S., Geography & Geological Science -- University of Idaho - College of Graduate Studies, 2023-0