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Modeling the Dynamic Response of Vertical Spent Nuclear Fuel Dry Storage Casks under Three-Dimensional Earthquake Wave Fields
No full textNuclear power generation has emerged as a promising alternative to fossil fuels, offering the potential for reduced carbon emissions and cleaner energy production. However, the long-term management of irradiated nuclear fuels poses a significant challenge. These materials require ongoing heat dissipation and exhibit high levels of radioactivity, complicating their storage and disposal, particularly in the absence of a permanent repository. In this context, Dry Storage Casks (DSCs) have been widely adopted as an interim storage solution, alluring several advantages, including minimal decommissioning cost, expedited transportation, and modular expansion capabilities. The proposed extension of operational lifespans for dry storage casks, typically deployed freestanding, has raised concerns regarding the long-term exposure to lateral extreme events. This makes them susceptible to sliding, rocking, and potential tip-over, leading to inter-cask collision during seismic events. Furthermore, soil-structure interaction (SSI) may significantly influence the dynamic response of such stiff structures founded on soft soil. While previous research studies have attempted to address this issue, they predominantly relied on one-dimensional (1D) deconvolution to transfer input motions at the base of the site soil stratigraphy, increasing the risk of oversimplification and erroneous prediction of SSI effects. Recent technological advancements in high-performance computing have enabled the routine generation of synthetic motions by leveraging simulation techniques, facilitating the capture of three-dimensional (3D) complex incident wavefields that affect structures. This research aimed to develop a workflow to utilize the outcome of such simulations in analyzing the response of DSCs while rigorously taking SSI effects into account. To this end, ground motions were extracted from a 3D geophysics model with a strike-slip fault rupture scenario capable of generating a M7.0 seismic event. Then, the domain reduction method (DRM) was implemented to port the motions to the DRM layer of a truncated soil domain generated in LS-DYNA. Three DSC configurations were investigated: a single cask model and two multiple cask arrangements oriented parallel or normal to the fault. Each model was analyzed considering both fixed and flexible bases at five different rupture distances. Results suggest that sliding and rocking are more predominant in the two near-field cases, while the cask response in the three far-field scenarios follows the ground response. In most situations, it was observed that the case incorporating the SSI produced higher responses than the cases without SSI. Additionally, input motion with more significant ground motion intensities induced higher cask sliding, indicating their potential positive correlation. Considerable variation in response characteristics, i.e., rocking, sliding, and CG level acceleration, was observed despite establishing a uniform frictional coefficient across DSCs in the multi-cask model, especially in the near-field cases. This series of experiments is expected to help future regulations, engineers, and licensing vendors consider at least some extremely unfavorable SSI analyses with multiple DSCs to ensure the safety of the dry storage facilities
Beyond the Silver and Gold: Investigations into the Capitalist Network of Downtown Aurora, Nevada from 1860 to 1864
No full textAs one of the initial boomtowns in Nevada, Aurora had an impact on the capitalistic system of Nevada. Aurora has a rich documentary record with which to reference. Using documentary archaeology, this thesis will document the existing businesses in the Study Area, categorizing them based on the goods and services they provide. Second, it assesses customer base of the businesses, determining the composition of the intended clientele. Lastly, the study identifies the owners and employees of these businesses, developing a demographic profile that includes an analysis of social identity categories such as gender, ethnicity, religion, and race. This aspect aims to explore how these identity categories influenced their engagement with the capitalist framework of Aurora, particularly in terms of business operations and potential exclusionary practices. Through this multifaceted examination, the research seeks to uncover the dynamics between business ownership, social identity, and customer interactions within the commercial landscape of downtown Aurora
Dynamic Zoning of Industrial Environments with Autonomous Mobile Robots
No full textWith the increasing adoption of autonomous mobile robots (AMRs) in manufacturing and warehouse environments, efficient task scheduling and resource allocation are critical for optimizing performance. This thesis presents two scheduling algorithms that divide a manufacturing/warehouse floor into zones that an AMR will occupy and complete part pick-up and drop-off tasks. Each zone is balanced so that every AMR will share each task equally. These zones change over time to accommodate fluctuations in production and to avoid overloading an AMR with tasks. To find the optimal zone design, we first present a re-engineered version of a simulated annealing (SA) algorithm using a genetic algorithm (GA). Then a Decentralized Dynamic Zoning (DDZ) algorithm is introduced, eliminating the possibility of single-point failure from a centralized unit. An experiment was conducted comparing the adaptability of each dynamic zoning system in a simulated industrial environment. Results show that the SA and GA methods share a similar throughput, but both DDZ and GA can achieve a better distribution of tasks. This could be useful for real-world applications by making it easier to design charging and maintenance schedules without much downtime. These algorithms provide a general strategy for both manufacturing and warehouse environments as they are designed to function in unpredictable scenarios where robots can only respond to the current demands of the system
Climate Driven Variation in Ice-out Impacts Zoobenthos Biodiversity and Production in a Subalpine Lake
No full textChanging winter-ice dynamics due to climate change are impacting lake benthic processes and ultimately lake ecosystem functioning. As lake ice conditions change, the impacts on lake benthic processes during subsequent ice-free seasons remain poorly documented. We examined the connections between ice-off dates and zoobenthic invertebrate diversity and productivity using a long-term ecological dataset from a subalpine lake. Zoobenthos were collected three times following ice-out from seven sites across the benthic habitat of a subalpine lake (four littoral, one sublittoral, and two profundal) over 15 years and identified to family. Ice-off dates were variable, ranging from Julian days 51 to 178. We identified 30 taxa, with Chironomidae, Oligochaeta, and Pisidium being the most dominant. Zoobenthic diversity differed between habitats, with the highest diversity in the littoral habitat, decreasing with depth. Zoobenthic richness was higher in early ice-out years in the littoral and sublittoral habitat, attributed to 13 families with low relative abundances, and some littoral sites were more sensitive than others. Zoobenthic productivity varied between habitats and was higher in the sublittoral habitats in late summer during years with early ice-out. Our results indicate that benthic communities remain resilient, showing no change in evenness with variation in ice-out date due to the robustness of the three dominant species. However, less abundant taxa may respond to continued early ice-out dates, and littoral habitats are more sensitive to these changes. The production of taxa is sensitive to ice-out conditions indicating potential implications for higher level consumers which feed on invertebrates within a lake (e.g.. fishes, amphibians) or rely on the adult insect emergence (e.g., bats, birds). This study suggests that benthic diversity and productivity while heterogeneous within a lake, may be sensitive to ice-out conditions which have been shown to occur earlier due to climate warming
Measurement and Modeling of Temperature and Charge State Distribution in Laboratory Photoionized Plasmas
No full textThe central focus of this work aims to extract the essence of the time-dependent response in the temperature and ionization behaviour of a laboratory photoionized plasma in response to a short, intense broadband x-ray pulse. The application of astrophysical simulations to laboratory experiments is a central goal, and the previous work has identified a stark inaccuracy in the temperature with an overestimation found with Cloudy and XSTAR of a factor of two. We find that the nature of this overestimation is strongly related to the transient effect of the radiation drive, when this is accounted for the overestimation drops significantly. This is supported by the characteristic timescale for the temperature simulated with the radiation-hydrodynamics code HeliosCR and in Cretin. Further, we find that the specific atomic model considerations and detail of Cloudy, the two-level model and the corresponding lack of a detailed treatment of excited state populations, are responsible for the remaining overestimation in the temperature of the time-dependent model relative to experiment. The ionizations across the suite of steady state and time-dependent models developed in Cloudy, Cretin, and PrismSPECT are compared with data, both time-integrated charge state distributions and time-dependent Li-like and H-like neon populations. For the charge state distribution, across the set of 9 experimental instances of ionization parameter, we find no model consistent with the data in all cases. When the temperature is held constant to the solution of the time-dependent model, and only the atomic kinetics is varied between steady state and time-dependent, we find that the each code indicates the presence of a transient effect in the atomic kinetics that is independent of the effect in the temperature. The transient effect in the atomic kinetics is supported by the characteristic timescales obtained with time-dependent data and consistent with the simulated population timescales. The transient effects intrinsic to the photoionized neon gas cell experiment on Z have inspired a successor, the photoionized expanding foil experiment on OMEGA EP. This venture seeks to produce the first steady state photoionized silicon plasma created in the laboratory, and we will show that this has been achieved. The plasma is diagnosed over many lines of sight using emission and transmission spectroscopy, and the VISAR interferometer, providing measurements of the sample expansion, charge state distribution, temperature, and driving radiation flux. We report initial comparisons of the transmission measurement with Cloudy and XSTAR steady state models. The success of this experiment has provided the motivation to field a platform for the photoionization of iron at the National Ignition Facility
Defining the Safety Impacts of Horizonal Curve Proximity on Rural Two-Lane Roads
No full textTo be complete
Border-Lines, Volume XI
No full textBorder-Lines is an interdisciplinary and intersectional academic journal dedicated to the dissemination of research on Chicana/o-Latina/o cultural, political and social issues. Border-Lines is a refereed journal that seeks to publish scholarly articles drawn from a variety of disciplines such as anthropology, education, geography, human health, literary and cultural studies, political science, social work and sociology
Enhancing Virus Reduction in Water Reclamation: Investigation of Long-Term Trends and Treatment Optimization Strategies
No full textPersistent enteric and respiratory viruses, shed into wastewater by symptomatic and asymptomatic individuals, pose significant public health risks if not adequately treated. Existing research often lacks resolution on treatment-level virus removal mechanisms and relies on idealized conditions, limiting its practical applicability. Building on long-term monitoring of SARS-CoV-2 genetic markers in wastewater across the Truckee Meadows region in Nevada, this study aimed to address the critical gaps in demonstrating the predictive power of wastewater concentrations towards public health, investigating the role fate mechanisms have in virus removal and demonstrating the removal efficiency of viral genetic markers in water reclamation. The specific objectives of this work are 1.) identify long-term trends in genetic marker shedding and assess wastewater's potential for predicting disease outbreaks; 2.) quantify the role of factors like adsorption, microbial predation, and endogenous decay in the removal of viral genetic markers in water reclamation processes; and 3.) demonstrate the efficacy of ozonation combined with soil aquifer treatment (SAT) in improving the removal of viral markers before groundwater recharge, especially in water resource-limited communities. The first phase of the work focused on monitoring SARS-CoV-2 genetic markers in untreated wastewater, correlating concentrations with reported clinical case data to identify trends and lead times in disease incidence, with notable peaks aligning with seasonal respiratory virus circulation. Consistent trends were observed, with peaks in disease incidents aligning with seasonal respiratory virus circulation and a 7-day lead-time identified through wastewater surveillance during the early pandemic. However, this was not observed during the circulation of the Delta and post-Omicron variants, possibly due to pandemic management, including vaccinations. Further research quantified viral genetic marker loss through conventional water reclamation processes, revealing negligible removal during primary treatment (p-value: 0.267) and highlighting adsorption during secondary treatment as a critical mechanism, with waste-activated sludge showing a peak concentration of 9.75 log10 GC/day for SARS-CoV-2 genetic markers. Finally, ozonation-SAT enhanced the removal of persistent viral genetic markers and recalcitrant chemical contaminants, including pharmaceuticals. For example, ozonation resulted in a >4-log reduction in norovirus genetic markers and a 2.35 ± 0.4 log reduction for PMMoV, with no significant difference observed between ozonated and non-ozonated SAT processes in PMMoV removal (p-value > 0.999). The ozonation-SAT system also significantly improved the removal of pharmaceuticals such as Sulfamethoxazole (95 ± 0.1%), Meprobamate (73 ± 0.1%), and Primidone (83 ± 0.1%), outperforming conventional SAT processes. These findings highlight the potential for integrating ozonation into existing treatment infrastructure to improve virus and contaminant removal for water reuse applications through SAT and groundwater recharge, particularly in communities with limited resources
Border-Lines, Volume XIV
No full textBorder-Lines is an interdisciplinary and intersectional academic journal dedicated to the dissemination of research on Chicana/o-Latina/o cultural, political and social issues. Border-Lines is a refereed journal that seeks to publish scholarly articles drawn from a variety of disciplines such as anthropology, education, geography, human health, literary and cultural studies, political science, social work and sociology
Leveraging Fourier Transform Infrared Spectroscopy to Elucidate Post-Fire Chemical Changes
No full textVegetation fires are a natural and common occurrence in forest ecosystems of the Sierra Nevada, resulting in changes to soils, vegetation, and hydrology. To successfully manage challenges of increased severity and frequency of fire and ensure the long-term health and sustainability of Sierra Nevada landscapes, continuous monitoring, and adaptive management efforts are needed. Land management strategies in fire-affected ecosystems require novel approaches that address soil water repellency (SWR), enhance water retention, and support vegetation recovery while acknowledging impacts on ecosystem resilience. This dissertation examined the relationships among temperature, charcoal, and SWR. First, laboratory methods of charcoal production in a controlled muffle furnace were compared with replicated fire conditions in a combustion facility. The heat-related chemical transformations of the produced charcoal were also compared using Fourier Transform Infrared (FTIR) spectroscopy and statistical analysis using Modern Analogue Technique (MAT). Mixed responses were observed when using FTIR spectra to infer fire temperature and vegetation species by measuring temperature changes in charcoal chemistry. Then, field-based data were collected to examine the relationships between burn severity, hydrophobic compound ratios, and infiltration rates for historic vegetation fire sites in the Sierra Nevada. An inverse relationship was found between hydrophobiccompound ratios, measured using FTIR, and soil water infiltration, emphasizing SWR in influencing post-fire soil hydrology. Finally, changes in the chemistry of vegetation fire collected charcoal to infer fire temperature using FTIR spectra were combined with infiltration measurements to examine temperature thresholds of SWR. Results showed that the relationship between charcoal temperatures collected from SWR soils needed to be clarified. Most charcoals had inferred temperatures above the threshold shown for SWR soils to occur, suggesting that charcoals could have been deposited from tree crowns and do not necessarily represent temperatures reached during fire for local soil microsite conditions. This study enhances our understanding of charcoal pyrolysis temperatures through FTIR analysis from a chemical standpoint. These findings have important implications for land management in fire-impacted ecosystems, highlighting the need forstrategies that mitigate soil erosion, improve water retention, and promote vegetation recovery, all while considering the role of SWR in ecosystem resilience