A bonding evaluation that investigated the cryogenic tensile strength of several different adhesives / resins was performed. The test materials consisted of 6061 aluminum test pieces adhered to a wet-wound graphite laminate in order to simulate the bond created at the liner-composite interface of an aluminum lined composite overwrapped pressure vessel. It was found that for cryogenic applications, a flexible, low modulus resin system must be used. Additionally, the samples prepared with a thin layer of cured resin - or prebond - performed significantly better than those without. It was found that it is critical that the prebond surface must have sufficient surface roughness prior to the bonding application. Also, the aluminum test pieces that were prepared using a surface etchant slightly outperformed those that were prepared with a grit blast surface finish and performed significantly better than those which had been scored using sand paper to achieve the desired surface finish. An additional impact investigation studied the post impact tensile strength of composite rings in a cryogenic environment. The composite rings were filament wound with several combinations of graphite and aramid fibers and were prepared with different resin systems. The rings were subjected to varying levels of Charpy impact damage then pulled to failure in tension. It was found that the addition of elastic aramid fibers with the carbon fiber mitigate the overall impact damage and drastically improve the post impact strength of the structure in a cryogenic environment.

This dissertation proposes the use of fiction as models to enhance the process of impact assessment (IA) and to improve the quality of IA reports. It demonstrates that works of extrapolative fiction (EF), a subset of science fiction, raise issues and clarify concerns not currently included in the IA process, suggesting the potential for improving the relevance of IA results for decisionmakers. The dissertation also demonstrates that EF stories can enhance the presentation of IA results, making those results more readable. Through literature review and content analysis, the current IA process is shown to lead to results lacking in specific content areas (e.g., effects on emotional well-being and community cohesiveness) necessary for their utility to decisionmakers. The body of literature here called extrapolative fiction is then shown to include many content areas missing in existing assessments. Two alternatives for an IA process that could incorporate extrapolative fiction are presented and discussed by means of examples. The first includes existing EF stories as a part of or an appendage to an IA report. The example is a preliminary combining of published EF stories with an IA report concerning life-extending technologies. The second includes the use of existing EF stories in the assessment process through inclusion of an EF-oriented reader on the IA team. The example is a case description of an IA process regarding the commercialization of guayule as a source of natural rubber, a process in which the author incorporated EF methods. Severa other results emerged from this research: (a) an initial statement of objectives for a unified field of impact assessment (recently emerging as an amalgamation of technology assessment, environmental impact statements and social impact assessment); (b) a working definition for an emerging subgenre of science fiction here called extrapolative fiction; (c) a topical bibliography of some hundred EF stories. These results extend the current understanding of the field of impact assessment and the emerging genre of extrapolative fiction and should be useful to both the impact assessment and science fiction criticism communities.

This study was designed to understand the possible impact of carbon dioxide on different reservoir rocks in south-central Mississippi. Eight samples, including six from the Heidelberg field (Mississippi), were exposed to carbon dioxide under simulated subsurface conditions of elevated temperature and pressure and then analyzed using thin section petrography, scanning electron microscopy, X-ray diffraction, and focused ion beam-SEM. Three of the eight samples showed dissolution in calcite and corrosion in smectite. SEM and EDS analysis of treated sample 5 (Se-5/shaly-sandtsone) and sample 8 (S-8/dolomitic-limestone) revealed newly precipitated lath- and fibrous-like crystals composed of sulfur (S), oxygen (O), and calcium (Ca), thus interpreted as gypsum. Three-dimensional analysis using FIB of dolomitic limestone samples (Smackover Formation) revealed that gypsum crystals fill fracture porosity. This study significantly contributes to the understanding of carbon dioxide impact on reservoir rock and promotes better management of natural gas resources.

Energy dissipation during penetration is an important consideration in materials selection for lightweight armoring to protect against hypervelocity impacts (HVIs). Impact-induced glass transition in polymeric materials has been observed to increase energy dissipation during penetration. Incorporating unconventional armor materials like polymers could improve performance in these types of applications. A series of HVIs was performed, with impact velocities over the range of 2-7 km/s, on samples of ultra-high molecular weight polyethylene and poly(methyl methacrylate). A relationship between back face debris cloud velocity and impact velocity was developed for each material. Damage zone sizes were compared, offering insights into the effects of molecular architecture on stress delocalization and energy dissipation during hypervelocity perforation. Thermal analysis of the two material systems provides quasi-static glass transition temperatures, as well as melting and crystallization temperatures. The apparent failure mechanisms, in conjunction with thermal analysis, were used to explain the relative performance of each material.

An aircraft may experience inlight ice accretion and corresponding reductions in performance and control when the vehicle encounters clouds of super-cooled water droplets. The EADS-IW Surface Engineering Group is investigating passive anti-icing possibilities, such as functional and ice phobic coatings. Ice-resistant coatings require investigating droplet impact on dry surfaces and wet films, including microscopic effects such as droplet splashing. To investigate droplet impacts, a volume of fluid (VOF) flow solver was used for droplets impacting dry and wetted hydrophobic and superhydrophobic surfaces, focusing on meso-scale simulations. The effects of structured, micro-scale surface roughness and the effects of a thin wet film on the surface, corresponding to a saturated surface under high humidity conditions, were investigated. Axisymmetric domains produced acceptable results for smooth, dry surfaces. It was determined that in order to properly predict behavior of droplets impacting surfaces with structured micro-scale roughness, three-dimensional simulations are recommended.

BACKGROUND: In the past decade urbanization has increased, with over half the world’s population and 83% of the total United States population, residing in urban areas as of 2021. Urbanization has the potential to decrease connectivity between nature and humans, impacting health and exacerbating urban heat islands. Previous research has found that the natural environment (i.e., trees and bluespace) provide vital ecosystem services through both direct and indirect pathways that positively impact health. Objective: The objective of my dissertation was to assess the current state of the natural environment in urban areas and gain a better understanding of the relationship between exposure to nature, health, and heat. METHODS: Research aims were addressed by focusing on publicly available data and a range of metrics used in previous literature to characterize exposure to greenness and natural landscapes and their associations with health and land surface temperature. In Chapter 2, I report on a nationwide quantitative health impact assessment to estimate the reduction in all-cause mortality in populations aged 65 and older in the largest metropolitan areas (n=35) in the United States associated with an increase in greenness in selected years across twenty years (2000, 2010, and 2019). Census tract mean seasonal greenness exposure was estimated by using the Normalized Difference Vegetation Index (NDVI) from Landsat 30 m 16-day satellite imagery from April to September. All-cause mortality estimates were downscaled from county to tract-level from the CDC WONDER Portal. Mortality reduction was estimated using a recently published exposure-response function. Chapter 3 focuses on urban census tracts in Massachusetts (n=525), in order to assess the cumulative exposure of the urban natural environment. Thirty candidate, validated measures of the natural landscape space were derived from data published between 2016 and 2019. Principal component analysis was used to reduce the number of candidate items and confirmatory factor analysis was used to test the underlying hypothesized latent structure of three sub-domains: green space, parks and recreation and blue space. Items hypothesized to measure each latent structure were summed using equal weights and each sub-domain was rescaled from 0–100. The tract-level cumulative exposure index was the sum of the three sub-domains. Lastly, in Chapter 4 using generalized linear models, I investigated the relationship between urban heat and nature using the natural landscape index created in Chapter 3 and mean five-year Land Surface Temperature (LST). The City of Boston was then used as a case-study to identify vulnerable tracts with low nature and high heat to inform planning for climate adaptation strategies and public health planning. RESULTS: In Chapter 2, overall greenness in the largest metropolitan areas in the US increased from 3% between 2000 and 2010 to 11% between 2010 and 2019. Approximately 34,000 to 38,000 all-cause mortality deaths could have been prevented with an increase in 0.1 NDVI units from 2000 to 2019. In developing the cumulative natural landscape index, in Chapter 3, we found that greenness measures (NDVI, tree canopy, percent impervious, etc.) explained the most variance among all of the items hypothesized to measure the cumulative natural landscape index. The three sub-domains explained 69% of the total variance, with greenness accounting more than half the total variance explained. Lastly, in Chapter 4, we report that with an interquartile shift in overall nature, LST decreased by 0.8°C. More specifically, higher overall greenness, higher percent tree canopy, and higher percent impervious surfaces resulted in the largest change in LST. With an increase in greenness and tree canopy we found a decrease in LST by over 1°C. In contrast, an increase in impervious surfaces resulted in an increase in LST by 1.31°C. Within the City of Boston, we found that 9% of the total population resides in tracts that were within the highest quartile of LST and lowest quartile of overall nature. CONCLUSION: Overall, this work finds that large urban areas in the United States saw a small increase in overall greenness across the past two decades. With a trend of increasing greenness there is also the potential to reduce all-cause mortality in those 65 years and older. Going beyond overall greenness, we created a cumulative natural landscape index to capture simultaneous exposures to the urban natural environment. Greenness measures such as tree canopy, NDVI, open space, and impervious surfaces explained the most variance in the cumulative nature index and was the most associated with LST as compared to parks and recreation and bluespace. We assessed the impacts of the natural landscape on temperature, and found that an increase in nature resulted in a significant decrease in LST with greenness measures having the largest impact. Results from these studies can be used to support climate action plans and greening initiatives to show the co-benefits of increased exposure to the natural environment and help identify areas that are lacking in these exposures to better implement initiatives.

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This dissertation is from the Joint Program Degree from the College of William & Mary and University of Virginia and awarded by the University of Virginia. The effects of petroleum hydrocarbons on salt marsh grasses and gastropods were examined under three different circumstances. In the first study reported, a small pocket marsh was repeatedly dosed with small amounts of a No. 2 fuel oil. The second study investigated the effects of a large accidental spill of No. 6 fuel oil. The third study involved single doses of a fresh and a weathered crude oil on artificially enclosed segments of marsh.

Sixty premenopausal women (age 25-50) finished a 16 week randomized controlled trial looking at the effects of different jump programs on hip and spine bone mineral density (BMD). Subjects were randomly assigned to a control group or one of two jumping groups. The Jump 10 group performed 10 jumps with 30 seconds of rest between jumps, twice daily, while the Jump 20 group performed the same protocol but with 20 jumps. At 8 weeks, BMD percent change (%Δ) at the hip was significantly different among groups when age, weight change, and subject compliance were simultaneously adjusted. In particular, the Jump 20 group had a greater %Δ in hip BMD compared to controls. However, %Δ in BMD for the neck of the hip (NOH), trochanter, or spine was not different among groups at 8 weeks. Following 16 weeks of jumping, BMD %Δ at the total hip and trochanter were significantly different among groups after adjusting for all covariates. Specifically, at the hip and trochanter, the Jump 10 and Jump 20 groups showed significantly greater %Δ in BMD compared to controls. There were no significant differences among groups for the BMD %Δ at NOH or spine at 16 weeks. Within-group analyses revealed no significant changes from baseline to 16 weeks for the jumping groups, but controls lost significant BMD. In conclusion, after 16 weeks of high-impact jump training, BMD at the hip and trochanter can be improved by jumping 10 or 20 times, twice daily, with 30 seconds of rest between each jump, compared to controls.