• Changing glaciers in the Brooks Range and western Chugach Mountains, Alaska: mass loss, runoff increase, and supraglacial volcanic tephra coverage

      Geck, Jason; Hock, Regine; Coakley, Bernard; Dial, Roman; Loso, Michael (2020-12)
      Glaciers in Alaska cover over ~87,000 km² (~ 6 % of the state) with most glaciers thinning and retreating at an increasing rate. The thinning and retreating of glaciers worldwide can have an immediate socio-economic implication in addition to the longer-term glacier meltwater contribution to sea level rise. This dissertation investigated Alaskan glaciers in the Brooks Range for mass loss and area reductions over the period 1970-2001 (Chapter 2), historic mass balance and runoff for Eklutna Glacier, located in western Chugach Mountains, using a temperature index model over 1984-2019 period (Chapter 3), and the persistence of tephra from a volcanic eruption of Mt. Spurr in 1992 on seven western Chugach Mountain glaciers (Chapter 4). Glaciers in the Brooks Range in Arctic Alaska (> 68° N) are important indicators of climate change and provide information on long-term climate variations in an area that has few high elevation meteorological stations. Digital elevation models (DEMs) reconstructed from topographic maps were differenced from an interferometric synthetic aperture radar DEM to calculate the volume and mass changes of 107 glaciers (42 km²). Over the period 1970-2001, total ice volume loss was 0.69 ± 0.06 km³ corresponding to a mean (area-weighted) specific mass balance rate of -0.54 ± 0.05 m w.e. a⁻¹ (± uncertainty). The arithmetic mean of all glaciers' specific mass balance rates was -0.47 ± 0.27 m w.e. a⁻¹ (± 1 std. dev.). A subsample of 36 glaciers found a 26 ± 16 % mean area reduction over ~35 years. Alaska's largest city, Anchorage, is critically dependent upon the melt water of Eklutna Glacier (29 km²) for both drinking water and hydropower generation; however, the glacier is rapidly retreating. We used a temperature index model to reconstruct the glacier's mass balance for the period 1985-2019 and quantify the impacts of glacier change on runoff. Eklutna Glacier experienced a significant annual mean surface mass balance negative trend (-0.38 m w.e. Decade⁻¹). Mean annual cumulative melt increased by 24 % between the 1985-93 and 2011-19 period. Additionally, the day of the year when 95% of annual melt has occurred was eight days later in the later time period than in the earlier period, demonstrating a prolongation of the melt season. The modeled mean annual discharge increased at a rate of 0.2 m decade⁻¹. This indicates that peak water, i.e. the year when annual discharge starts decreasing as the glacier becomes smaller, has not been reached. The past increases in runoff quantity and melt season length provide opportunities for water resource managers that must be balanced against future decreased runoff as the glacier continues to shrink. Volcanic eruptions deposit volcanic tephra on glaciers in Alaska, modifying surface albedo and glacier melt. We mapped the distribution of tephra originating from the eruption of Mt. Spurr in 1992 using aerial photos and satellite imagery on seven glaciers located approximately 180 km east of the volcano in western Chugach Mountains in southcentral Alaska. The glaciers were completely covered with ≥ 500 g m⁻² tephra immediately after the event. Tephra deposits are still visible on all glaciers 26 years after the eruption. Using LandSat 8 surface reflectance bands, we quantified percentages of tephra glacier coverage. Results suggest an increasing tephra extent on five of the seven investigated glaciers over 2013-2018 period explained by firn line retreat. The mean percent increase for all glaciers was 4% with Troublesome Glacier showing greatest increase (~ 7 %) and Finch Glacier showing a slight decrease (~ 1 %). This long- term tephra persistence on glacier surfaces most likely enhanced melt although the precise effect remains unknown.
    • Characterization of water-soluble brown carbon (WS-BrC) from boreal forest wildfires in the summer season at northern high latitudes

      Banerji, Sujai; Mao, Jingqiu; Simpson, William R.; Guerard, Jennifer J. (2021-05)
      In the current study, we quantify the absorption Ångström exponent (AAE) and the mass absorption coefficient (MAC) of water-soluble brown carbon (WS-BrC) from boreal forest wildfires. We deployed a Particle into Liquid Sampler (PILS) - Liquid Waveguide Capillary Cell (LWCC)-Total Organic Carbon analyzer (TOC) system in downtown Fairbanks during the summer of 2019, to measure the light absorption by WS-BrC between around 200 nm to around 800 nm wavelength range every four minutes, and the concentration of the water-soluble organic carbon (WSOC), every two minutes. We then compute the AAE and MAC to examine the optical properties of brown carbon from boreal forest fires. During this period, several forest fires burned and we sampled particles from these fires. We explored a number of quantitative methods to compute the AAE and find that using the entire wavelength range of 300 nm to 350 nm appears to best represent the wavelength dependence of BrC absorption, in contrast to using just a pair of two wavelengths. The calculated AAE is observed to be ~3 for smaller wildfires and above ~3 for medium and large wildfires, whereas the calculated AAEnew is observed to be ~5 during the sampling of small, medium and large wildfires. The calculated MAC at 365 nm (MAC₃₆₅) tends to be ~1.0 m² g⁻¹ and remains relatively constant during wildfire events. We further compare these values to measurements reported from mid-latitude wildfires, to quantify the difference between the wildfires in Alaska and Canada from that of the wildfires in the contiguous U.S.
    • Climate change, moose, and subsistence harvest in Arctic Alaska

      Zhou, Jiake; Kielland, Knut; Kofinas, Gary; Tape, Ken D.; Prugh, Laura (2020-08)
      Arctic climate is resulting in transformative changes to Arctic social-ecological systems. With warming-induced increases in tall-shrubs, moose are expanding their range northwards. However, the socio-economic implications of this ecological change are unclear. Using field surveys, interviews, and modeling, I assessed the impact of climate change on moose harvest by hunters of Nuiqsut, an Inupiat community in arctic Alaska. Based on a 568 km transect of field sampling on shrubs and herbivore browsing levels, I estimated that the minimum shrub height for moose occurrence was ≥ 81 cm (95% CI: 65 - 96 cm). Patterns of moose geographic distribution mirrored tall-shrub distribution in arctic riparian areas. I also found that snowshoe hares may impact moose habitat via potential resource competition. Habitat suitability models, using Maxent and simpler temperature-threshold models, predicted that moose habitat may more than double by 2099 if current warming trends continue. The model outputs also suggested that climate warming will likely increase habitat connectivity, enhancing range expansion of moose in the Arctic. Finally, I used a coupled social-ecological systems (SES) framework to assess the implications of changes in tall-shrub habitat to moose harvest under future warming. Despite the expected increase in moose habitat and distribution, simulations of an agent-based model showed that the future may not translate into greater harvest opportunities, largely due to the limitation of river navigability for hunters. These findings provide an example in which rapid landscape and resource change may not translate into increased harvest. The integrated assessment with a SES framework revealed new and surprising outcomes, not evident when evaluating social and ecological components separately. This analysis highlighted how a coupled social-ecological framework can be used to assess the effects of climate change on ecosystem services.
    • Coastal wetland carbon and mineral responses to storm and climate change through time, at Cape Espenberg Alaska

      Smith, Lindsey Michelle; Maio, Chris; Bigelow, Nancy; Eagle, Meagan (2022-05)
      The Arctic is experiencing warming and ecological shifts due to climate change and the compounded effects of polar amplification. There is a deficit of information surrounding the carbon cycle response in Arctic Alaskan coastal marsh environments to these forces. The Cape Espenberg barrier beach system has been mostly preserved through time as a shoreline-parallel, linear geometry prograding geomorphic feature. This study determines the Arctic carbon and mineral accumulation trends in marsh environments at Cape Espenberg for both paleo (pre 1850 AD) and modern (post 1850 AD) timeframes. This project makes connections between the responses of carbon and mineral materials to paleo and modern climate changes, and how this relationship may have evolved through time. Analytical analyses through radioisotope ¹³⁷Cs and ²¹⁰Pb, ¹⁴C, stable isotope spectrometry (δ¹³C), elemental (%C, %N, C:N), and dry bulk density and carbon density measurements yield a comprehensive physical and chemical dataset. Radioisotope dating techniques in the Arctic have proved challenging due to the dynamism of the environment. However, the combination of Constant Rate of Supply and Constant Initial Concentration age depth models has helped constrain ages to sediment cores even under variable conditions. Results indicate carbon and mineral accumulations have increased from paleo to modern times which indicates better growing and/or preservation conditions for organic matter (OM) under a modern climate. This agrees well with paleoclimate trends in the Medieval Climate Anomaly (MCA), and warm periods interspersed within the Little Ice Age (LIA), which correlate to greater productivity of terrestrial organic matter and isotopically lighter δ¹³C values (a terrestrial signature). Cold climate periods within the Little Ice Age correlate with increased aquatic organic matter sourcing and heavier δ¹³C values. Modern warming will likely continue to drive carbon sourcing towards terrestrial signatures as future temperatures are predicted to rise with global climate change. If the swale environments at Cape Espenberg can maintain ideal growing conditions (i.e. wet/anoxic soils and lower salinity to limit organic material decay, higher temperatures to promote growth) then Cape Espenberg will likely remain a viable carbon reservoir in the future. However, the question of whether the barrier system as a whole will continue to prograde under a regime of rising sea levels and increased storm impacts is unclear. The results of this study contribute towards understanding the dynamism of Arctic coastline mineral and carbon cycling and their ecological response to the current warming climate.
    • Community composition and biogeography of beetles and spiders across an elevational gradient in Denali National Park, Alaska

      Haberski, Adam; Sikes, Derek S.; Hollingsworth, Teresa; Armbruster, W. Scott (2020-08)
      Anthropogenic climate change is rapidly altering alpine ecosystems in Alaska. Trees and woody shrubs are expanding upslope and displacing alpine tundra. As alpine tundra habitats shrink and fragment, arthropods and other animals face an increased risk of extirpation due to smaller population sizes and reduced geneflow. Arthropods--insects, spiders, and their relatives--are the most speciose component of the alpine fauna and perform key ecosystem services, such as pollination and nutrient cycling, and are food for vertebrates. Many species have responded by shifting their distribution to higher elevations, but species respond to change idiosyncratically, which could alter species interactions and disrupt communities. I compared beetle and spider communities along an elevational gradient in Denali National Park and Preserve, Alaska, an area with a complex biogeographic history and a poorly known arthropod fauna, in order to 1) examine differences in diversity, abundance, and community composition among forest, shrub, and alpine tundra habitats; 2) link the observed differences to abiotic factors relevant to climate change; and 3) test if shared habitat preferences lead to community-level patterns in geographic distribution. After three consecutive summers of sampling, I found that alpine tundra supports an unexpectedly diverse arthropod community with a high proportion of unique species and that vegetation cover and mean air temperature are strongly correlated with community composition. I therefore expect species losses among alpine tundra communities as shrubification continues. Community-level distribution patterns were not observed, but trends in the data point to a reduction of Holarctic distributions among forest-dwelling arthropods and an increased proportion of Beringian endemics among tundra species. This was the first systematic survey of Denali's terrestrial arthropods and added over 450 new park records.
    • A comparison of surface moisture budget and structural equation models in high latitudes: evapotranspiration and atmospheric drivers

      Thunberg, Sarah M.; Walsh, John; Euskirchen, Eugenie; Bhatt, Uma S. (2021-08)
      Arctic soil moisture is one of the most impactful and unknown aspects of the Arctic climate system. As the climate changes, surface soil moisture can impact water supplies, wildfire risk, and vegetation stress, all of which have consequences for terrestrial ecosystems and human activities. The present analysis is intended to (1) document seasonal and interannual variations of surface moisture fluxes in the Arctic region and (2) clarify the drivers of variations of net Precipitation minus Evapotranspiration (P-ET) across Arctic tundra and boreal vegetation and permafrost status. Forty-five flux tower sites were examined across boreal and tundra ecosystems across the Arctic and sub-arctic. The surface moisture budget at boreal forest sites in permafrost areas generally shows a moisture deficit in late spring and early summer, followed by a moisture surplus from late summer into autumn. The annual net P-ET is generally positive but can vary interannually by more than an order of magnitude. A factor analysis found the primary drivers of variations in evapotranspiration to be radiative fluxes, air temperature, and relative humidity, while a path analysis found windspeed to have the largest independent influence on evapotranspiration. Overall, the ET at boreal forest sites shows a stronger dependence on relative humidity, and ET at tundra sites shows the stronger dependence on air temperature. These differences imply that tundra sites are more temperature-limited and boreal sites are more humidity-dependent. Relative to nearby unburned sites, the recovery time of ET after disturbance by wildfire was found to vary from several years on the Alaska tundra to nearly a decade in the Alaska boreal forest.
    • Computational analysis of nanofluids flow and heat transfer in microchannels and fin tube air coils

      Ray, Dustin R.; Das, Debendra K.; Peterson, Rorik A.; Misra, Debasmita; Kim, Sunwoo (2021-05)
      The four goals of this dissertation were to investigate nanofluids' thermal and fluid dynamic performance in (i) an air coil, (ii) microchannel heatsink, using computational fluid dynamic (CFD) software, ANSYS Fluent, develop (iii) hydrodynamic entrance length correlation and (iv) apparent friction factor correlations in rectangular microchannels. In cold regions of the world, ethylene glycol mixed with water (EG/W) are used as a heat transfer fluid instead of water due to their freeze protection. EG/W has low thermal conductivity than water, which can be improved by dispersing nanoparticles and creating a new fluid called nanofluid. A computational scheme was developed based on the Effectiveness-Number of Transfer Unit (ε-NTU) method to compare nanofluids' thermal and fluid dynamic performance to the conventional ethylene glycol and water mixture. The nanofluid's performance was examined by conducting two studies: reducing pumping power and reducing the air coil's surface area via length. The results showed at a dilute concentration of 1% of Al₂O₃ can reduce the pumping power requirements by 35.3% or reduce the air coil length by 7.4% while maintaining the same heat transfer rate as EG/W. The results show nanofluids could provide significant savings in energy or material costs. The nanofluids' (Al₂O₃, CuO, and SiO₂) thermal and fluid dynamic performance used in a microchannel heatsink was explored using analytical and computational methods. The computational model was developed in ANSYS Fluent. Comparing analytical and computational results, good agreement was observed validating both methods. The three nanofluids had a maximum difference of 4.1% for pressure drop and 2.9% for the Nusselt number. Three performance studies were conducted using the analytical model based on constant Reynolds number, maximum surface temperature, and pumping power. A constant Reynolds number of nanofluids could reduce the maximum surface temperature by 6K, but at the cost of increased pumping power. Nanofluids showed the pumping power could be reduced by 23% compared to the base fluid while maintaining equal maximum surface temperature. In electronic cooling applications where microchannel heatsinks are used, nanofluids seem promising for lowering critical components' operating temperatures and contribute to increased life and system reliability. A detailed three-dimensional laminar flow CFD model was developed and ran for Reynolds numbers ranging from 0.1 to 1000 through six rectangular microchannels aspect ratios (α): 1, 0.75, 0.5, 0.25, 0.2, 0.125. The majority of the Reynolds numbers simulated were in the low regime (Re< 100) to fulfill the lack of literature for determining accurate hydrodynamic entrance length and apparent friction factor for microchannels. From these numerical simulations, improved correlations were developed to predict hydrodynamic entrance length with a mean error of less than 2% and a maximum error of 5.75% for 0.1 ≤ Re ≤ 1000 & 0 ≤ α ≤ ∞. For the apparent friction factor in microchannels, three correlations were derived from the numerical simulations: fully developed friction factor (fRe), developing incremental pressure drop number (K(z)), and fully developed incremental pressure drop (K(∞)). The three correlations were used to determine the local fapp,zRe, in the applicable range of 0.1 ≤ Re ≤ 1000 & 0.125 ≤ α ≤ 8. The correlations showed a mean deviation of less than 3% and a maximum deviation of less than 8.3% from the numerical data.
    • Computational and experimental evaluation of nanofluids in heating and cooling forced convection applications

      Strandberg, Roy; Das, Debendra K.; Peterson, Rorik A.; Johnson, Ronald A.; Goering, Douglas J. (2021-05)
      The purpose of the research was to examine the heat transfer and fluid dynamic performance of various nanofluids in heating and cooling applications using empirical and computational methods. Two experiments were performed to characterize and compare the performance of a Al₂O₃/60% ethylene glycol (60% EG) nanofluid to that of its base fluid. In the first experiment, the nanofluid was comprised of Al₂O₃ nanoparticles with 1% volumetric concentration in a 60% ethylene glycol/40% water (60% EG by mass) solution to that of 60%EG in a liquid to air heat exchanger. The test bed used in the experiment was built to simulate a small air handling system typical of that used in heating, ventilating and air conditioning (HVAC) applications. Previously established empirical correlations for thermophysical properties of fluids were used to determine the values of various parameters (e.g. Nusselt number, Reynolds number, and Prandtl number). The testing shows that the 1% Al₂O₃ nanofluid generates a marginally higher heat rate than the 60% EG under certain conditions. At Re=3,000, the nanofluid produced a heat rate that was 2% higher than that of the 60% EG. The empirically determined Nusselt number associated with the convection inside the coil tubing follows the behavior predicted by the Dittus-Boelter correlation quite well (R²=0.97), while the empirically determined Nusselt number for the 60% EG follows the Petukhov correlation similarly well (R²=0.97). Pressure loss and hydraulic power for the nanofluid were higher than for the base fluid over the range of conditions tested. The exergy destroyed in the heat exchange and fluid flow processes were between 8 and 13% higher for the nanofluid over the tested range of Reynolds numbers. The objective of the second study was to experimentally characterize and compare the performance of a nanofluid comprised of Al₂O₃ nanoparticles with 1, 2 and 3% volumetric concentrations in a 60% EG solution to that of 60% EG in a liquid to air heat exchanger. In this experiment, the heating system was operated in a higher temperature regime than in the first experiment. As in the first experiment, the test bed used in the experiment simulated a small air handling system typical of that used in HVAC applications. Entering conditions for the air and liquid were selected to emulate typical operating conditions of commercial air handling systems in sub arctic regions (such as Alaska). In the experiment the nanofluids generally did not perform as well as expected based on previous analytical work. The performance of the 1% nanofluid was generally equal to that of the base fluid considering identical entering conditions. However, the 2% and 3% nanofluids performance was considerably worse than that of the base fluid. The higher concentration nanofluids exhibited heat rates up to 14.6% lower than that of the 60%EG, and up to 44.3% lower heat transfer coefficient. The 1% Al₂O₃/60% EG exhibited 100% higher pressure drop across the coil than the base fluid considering equal heat output. In the computational portion of the research, the performance of a microchannel heat sink (MCHS), similar to those used to cool microprocessors filled with various nanofluids and the corresponding base fluid without nanoparticles are examined. The MCHS is modeled using a three- dimensional conjugate heat transfer and fluid dynamic finite-volume model over a range of conditions. The model incorporates a fixed heat flux of 1,000,000 W/m² at the base of the solid domain. The thermophysical properties of the fluids are based on empirically obtained correlations, and vary with temperature. Nanofluids considered include 60% Ethylene Glycol/40% Water solutions with CuO, SiO₂, and Al₂O₃ nanoparticles dispersed in volumetric concentrations ranging from 1 to 3%. The flow conditions analyzed are in the laminar range (50£Re£300), and consider multiple inlet temperatures. The analyses predict that when compared on an equal Reynolds number basis, the 60%EG/3% CuO nanofluid exhibits the highest heat transfer coefficient, and the largest reduction in average base temperature. At an inlet Reynolds number of 300, and an inlet temperature of 308K the nanofluid is predicted to have an average heat transfer coefficient that is 30% higher than that of the base fluid, while the average temperature on the base of the heat exchanger is 1K lower than that of the base fluid. In contrast, the inlet pressure required for these entering conditions is 192% higher than that for the base fluid, while the required hydraulic power to drive the flow is 366% higher than that of the base fluid. The enhanced heat transfer performance potential of nanofluids comes at the expense of generally higher pumping power consumption.
    • Conceptual design of two tiltrotor aircraft for urban air mobility

      Radotich, Michael T.; Peterson, Rorik; Chen, Cheng-fu; Hatfield, Michael (2021-12)
      There has been an abundance of new and novel aircraft designs created for Urban Air Mobility (UAM) in recent years. The National Aeronautics and Space Administration (NASA) contributes to the research and development of this industry in part by applying its aircraft design tools to create conceptual designs of UAM reference vehicles. The vehicles are intended to quantify the tradeoffs and performance capabilities necessary for VTOL (vertical takeoff and landing) aircraft in the UAM design space. The reference vehicles represent a variety of configurations that seek to encompass many of the design characteristics suitable for UAM. This thesis focuses on the conceptual design process of two new NASA reference vehicles. Both aircraft are configured as conventional tiltrotors, but one is powered by turboshaft engines, and one is fully electric. The sizing and performance of the two aircraft are discussed, as well as how the performance and characteristics compare to a selection of other NASA reference vehicles. It is found that the tiltrotor configuration is capable of reaching speeds 43% to 51% faster than the other turboshaft designs, and 63% to 106% faster than the other electric designs. The increased speed leads to a 24% to 42% decrease in overall mission time. With this speed increase comes moderate tradeoffs in areas including weight and installed power.
    • Contextualizing the development of coastal adaptations in postglacial Southeast Alaska

      Schmuck, Nicholas S.; Reuther, Joshua; Clark, Jamie; Baichtal, James F.; Holliday, Vance T.; Plattet, Patrick (2021-05)
      The goal of this dissertation is to improve our understanding of human population expansions into unfamiliar environments, focusing on when and how humans adapted to the rich coastal landscape of Southeast Alaska. Investigation of the peopling of this region has been overshadowed by the broader narrative that the Americas may have been first colonized by a late Pleistocene coastal migration. Refinements to local sea-level and paleoecological chronologies help contextualize the dynamic landscape that these first inhabitants might have encountered, returning focus to the archaeology of Southeast Alaska itself. This research considers existing archaeological data within the theoretical framework of Human Behavioral Ecology, proposing new models to acknowledge the process of landscape learning. Landscape learning provides a mechanism for exploring human adaptation to unfamiliar landscapes, which in turn produces testable hypotheses based on the familiarity of colonizing human foragers with coastal environments. Systematic sourcing of obsidian microblade cores, ubiquitous in early Holocene sites, allows for a further assessment of landscape learning, alongside an evaluation of the relationship between local raw material constraints and technological organization. Though the oldest known archaeological sites in Southeast Alaska are firmly dated to between 10,500 and 10,000 cal BP, older occupations have been identified elsewhere on the Northwest Coast, and Tlingit and Haida oral histories record their presence on the landscape from Time Immemorial. Taken together, multiple lines of evidence point to an initial colonization of Southeast Alaska out of eastern Beringia, occurring prior to the occupation of the oldest known sites. By the early Holocene, foragers with a typical Northwest Coast diet were readily adapting to, but still in the process of learning, this complex coastal landscape. While these results challenge the long-established impression that the oldest known sites in the region represent a remnant population of maritime sea-mammal hunters descended from an earlier coastal migration into the Americas, this research highlights the opportunity to continue testing these hypotheses by targeting older, uplifted paleoshorelines.
    • Control of internal transport barriers in magnetically confined tokamak fusion plasmas

      Panta, Soma Raj; Newman, David; Wackerbauer, Renate; Ng, Chung Sang; Sanchez, Raul (2020-07)
      In the Tokamak plasma, for fusion to be possible, we have to maintain a very high temperature and density at the core at the same time keeping them low at the edge to protect the machine. Nature does not favor gradients. Gradients are source of free energy that causes instability. But we require a large gradient to get energy from plasma fusion. We therefore, apply a huge magnetic field on the order of few Tesla (1 T-10 T) that confines the plasma in the core, maintaining gradients. Due to gradients in density of charged particles (ions and electrons), there is an electric field in the plasma. Heat and particle transport takes place from core to edge mainly through anomalous transport while the E x B velocity sheer acts to reduce the transport of heat and particles. The regime at which the E x B velocity shear exceeds the maximum linear instability growth rate, as a result, the transport of particles and heat gets locally reduced is termed as the formation of a transport barrier. This regime can be identified by calculating the transport coefficients in the local region. Sometimes it can be observed in the edge where it is called an edge barrier while if it is near the core it is an internal transport barrier. There is a positive feedback loop between gradients and transport barrier formation. External heating and current drives play an important role to control such barriers. Auxiliary heating like neutral beam injection (NBI) and radio frequency (RF) heating can be used at a proper location (near the core of the plasma) to trigger or (far outside from the core) to destroy those barriers. Barrier control mechanism in the burning plasmas in international thermonuclear test reactor (ITER) parameter scenarios employing fusion power along with auxiliary heating source and pellets are studied. Continuous bombardment with pellets in the interval of a fraction of a second near the core of the burning plasma results in a stronger barrier. Frozen pellets along with auxiliary heating are found to be helpful to control the barriers in the tokamak plasmas. Active control mechanism for transport barriers using pellets and auxiliary heating in one of tokamaks in United States (DIII-D) parameter scenarios are presented in which intrinsic hysteresis is used as a novel control tool. During this process, a small background NBI power near the core assists in maintaining the profile. Finally, a self-sustained control mechanism in the presence of core heating is also explored in Japanese tokamak (JT-60SA) parameter scenarios. Centrally peaked narrow NBI power is mainly absorbed by ions with a smaller fraction by the electrons. Heat exchange between the electron and ion channels and heat conduction in the electron channel are found to be the main processes that govern this self control effect. A strong barrier which is formed in the ion channel is found to play the main role during the profile steepening while the burst after the peaked core density is found to have key role in the profile relaxation.
    • Cultural adaptations of evidence based practices in supporting children diagnosed with autism spectrum disorder

      James, Krista P.; Barnhardt, Raymond; Leonard, Beth; Wells, Cassie; Healy, Joanne (2020-08)
      Research shows that early identification and intervention result in a higher quality of life and contribution to society for individuals with Autism Spectrum Disorder (ASD). As society sees an ever-increasing percentage of individuals diagnosed with ASD, identification of culturally responsive, evidence-based practices is of critical importance. While the National Autism Center has provided a guide to evidence-based practices, minimal research has been done to determine if these practices are culturally relevant. This is a community-based formative research project. The purpose of this project was to evaluate the cultural appropriateness of the practices identified as "evidence-based practices" by the National Autism Center in the 2015 standards report, specifically a token economy system which is a positive behavioral support that utilizes the principles of applied behavior analysis to decrease challenging behaviors and increase positive behaviors. The study utilized qualitative research strategies, including surveys and interviews within the American Samoan community, to accomplish this evaluation. The surveys and interviews were analyzed using coding principles to generate themes. The researcher was contacted by the American Samoan Department of Education to provide training for educators and parents on utilizing evidence-based practices to support children with autism. The results of this study inform the content of the ongoing training efforts.
    • Current and novel tools in the health assessment of large whales

      Cates, Kelly Ann; Atkinson, Shannon; Bejder, Lars; Cunningham, Curry; Mueter, Franz; Straley, Janice (2021-08)
      Alaskan marine ecosystems are undergoing unprecedented change and species are facing increasingly variable and potentially inhospitable habitats. As top predators, marine mammals serve an important role as sentinels of ecosystem health. With their high site fidelity, abundant numbers, coastal presence and role as a top predator, humpback whales (Megaptera novaeangliae) provide a meaningful view into current ecosystem conditions and processes. In order to tap into their usefulness as bioindicators the basic physiology of humpback whales needs to be understood. Physiological indices can provide valuable information about fecundity, survival, health and population age structuring which is fundamental to cetacean research and population management. However, such information is often difficult to obtain from wild cetaceans as they surface infrequently and often live in remote or logistically challenging locations. As such, few methods currently exist for the assessment of physiological parameters of free ranging, large cetaceans. This dissertation paired existing methods of physiological examination with novel approaches in order to better understand the basic physiology and overall health of humpback whales. Specifically, six enzyme immunoassays were validated for use in humpback whales for progesterone, testosterone, cortisol, corticosterone, aldosterone and DHEA-S, an algorithm termed "Morphometer" was developed to automate the process of measuring and analyzing morphometric measurements, and hormones and body condition metrics were paired to determine whether pregnancy status can be detected from aerial photographs. This project seeks to lay the groundwork for long term monitoring of humpback whales that can provide critical information to managers. By using baseline physiological indices and tools to rapidly analyze these metrics that I developed here, managers and researchers will be able to analyze current and future samples within a longitudinal context and make management decisions based on more accurate biological information for these populations.
    • Current exposure of Yukon Flats tribal villages' residents to PM₂.₅ from natural and anthropogenic sources: establishing baselines for climate change adaptation and resilience

      Edwin, Stanley G.; Mölders, Nicole; Collins, Richard L.; Fochesatto, Javier; Stuefer, Martin (2020-08)
      How healthy is the air in the villages during the summer fire seasons? Why does Fort Yukon always seem to be colder than the surrounding villages in winter and spring? How healthy is the air we breathe in our homes and workplaces? These are but a few of the questions asked by Alaska's Eastern Interior residential village's Indigenous Tribal Governments. A tribal-owned network of aerosol monitors and meteorological stations was installed at Ts'aahudaaneekk'onh Denh, Gwichyaa Zheh, Jałgiitsik, and Danzhit Khànlaj̜j̜ in the Yukon Flats, Alaska. To assess the exposure of residents in rural communities in the Yukon Flats to particulate matter of 2.5 [micro]m or less in diameter (PM2.5), both indoor and outdoor concentration observations were carried out from spring 2017 through to August 2019. Surface-based-temperature inversions occurred under calm wind conditions due to surface radiative cooling. In May, local emissions governed air quality with worst conditions related to road and river dust. As the warm season progressed, worst air quality was due to transport of pollutants from upwind wildfires. Absorption of solar radiation in the smoke layer and upward scattering enhanced stability and fostered the persistence of the surface-based-temperature inversions. Under weak large-scale forcing mountain-valley circulations develop that are driven by the differences in insolation. During the long dark nights, surface radiative cooling occurs in the near-surface layer of the mountain slopes of the Brooks, Ogilvie and White Mountains Ranges and at the bottom of the valley. Here surface-based-temperature inversion - known as roof-top inversions - form, while the cold air drains from the slopes. A frontal wedge forms when the cold air slides over the relatively colder air in the valley. Drainage of cold air from the Brooks Range governed the circulation and cold air pooling in the valley. At the site, which is closest to the mountains, concentrations marginally changed in the presence of temperature inversions. Indoor concentrations were measured at 0.61 m in homes and at 1.52 m heights both in homes and office/commercial buildings. Air quality was better at both heights in cabins than frame homes both during times with and without surface-based-temperature inversions. During summer indoor concentrations reached unhealthy for sensitive groups to hazardous conditions for extended times that even exceeded the high outdoor concentrations. Indoor and outdoor concentrations were strongest related for office/commercial buildings, followed by frame houses and cabins. These are but a few of the answers found in this research of meteorology effects, unhealthy locations for breathing PM2.5 air outdoors and in homes.
    • Design, manufacture, and testing of a modular array for three-dimensional photovoltaics

      Fiscus, Trevar; Peterson, Rorik; Huang, Daisy; Denkenberger, David (2020-08)
      The emerging technology of three-dimensional photovoltaics is explored, shedding light on past research, current developments, and recommendations for future work. Research was performed at the University of Alaska Fairbanks analyzing six different geometric configurations of solar cells, both computationally and experimentally. The primary work described in this paper is the design and production of a modular solar array prototype and the experimental setup used to test the power output of the different configurations. Data collected from hundreds of tests were processed and analyzed to find optimum configuration angles and recommendations for future research. Working through the process of designing and manufacturing the equipment, and then subsequently using it for experimentation, provided many insights into recommended improvements. This text is organized into eight chapters that detail the background of research in using three-dimensional space for solar power generation, the recent project completed at the University of Alaska Fairbanks, and the proposed guidance for future work on this topic. This paper and use of the sources cited herein should provide the reader with the background and tools necessary to continue research. The latter chapters should act as a guide for the future design of components to be used in laboratory experimentation. It is hoped that this report, the collected data, and associated files from this project will add to the knowledge base of threedimensional solar arrays and help advance the technology one step closer to real-world application.
    • The development and initial testing of the vertical comet assay, a novel technique for the study of DNA damage and repair

      Williams, Robert T. D.; Pdlutsky, Andrej; Chen, Cheng-fu; Drew, Kelly (2021-05)
      Gene-specific repair is the idea that certain segments of the genome repair at a faster rate than others. This idea, if demonstrated with adequate evidence, would have large implications for the field of biology as a whole, with special significance for the fields of oncology, gerontology, and molecular and cell biology. The concept of gene-specific repair is not new, with the earliest references in the literature dating back to 1985, and there is a small volume of evidence derived over the years. However, the evidence generated so far is not enough to conclusively prove the existence of gene-specific DNA repair. Generally, the reason for the lack of evidence is that currently available assays and techniques are not adequate for the study of gene-specific repair on a large scale as the techniques that are available require a great deal of time, funding, and skill to generate a reliable and conclusive data set for a single gene, let alone the entire genome. The vertical comet technique described here-in is a response to the perceived need for a robust and relatively high-throughput technique for the study of gene-specific DNA repair. In the traditional comet assay, cells are fixed in agarose gel. Electrophoresis is performed, following several treatment steps, to create a ball of nuclear material embedded in the agarose gel with a 'tail' of smaller pieces of nominally damaged DNA extending to one side. The vertical comet captures this tail DNA in a buffer, allowing for its further analysis with processes such as quantification, PCR/qPCR, and sequencing. The capture of the tail DNA not only makes genespecific repair studies possible, it also allows the vertical comet to fulfill the role of the traditional comet assay with a number of advantages - a reduction in human bias, a reduction in labor-hours required for work, and a reduction in inter-lab variability of results.
    • Development of a vertical oscillator energy harvester: design and testing of a novel renewable resource power conversion system

      Wise, Michael A. Jr.; Al-Badri, Maher; Wies, Richard Jr.; Kasper, Jeremy (2020-12)
      Remote Alaska communities have historically dealt with elevated electric power expenses due to high cost of transporting diesel fuel for power generation. To offset this cost, the installation of various renewable resources have been utilized, particularly wind and solar power. Hydrokinetic generation by harnessing river flows is an emerging and less commonly implemented renewable resource that offers great potential for power generation. Specifically, this study investigates the behavior of a novel concept for harnessing vertical oscillation that occurs when a bluff body is inserted into a flow path. Unlike traditional rotating turbines used in hydrokinetic energy, this particular device utilizes the fluid structure interactions of vortex-induced-vibration and gallop. Due to the unique characteristics of this vertical motion, a thorough examination of the proposed system was conducted via a three-pronged approach of simulation, emulation, and field testing. Using a permanent magnet synchronous generator as the electrical power generator, an electrical power conversion system was simulated, emulated, and tested to achieve appropriate power smoothing for use in microgrid systems present in many Alaskan rural locations.
    • Development of scalable energy distribution models to evaluate the impacts of renewable energy on food, energy, and water system infrastructures in remote Arctic microgrids of Alaska

      Karenzi, Justus; Wies, Richard; Huang, Daisy; Al-Badri, Maher (2020-08)
      Experience and observations from remote Alaska communities have shown that energy is inarguably at the center of food, energy, and water (FEW) security. The availability of potable water, fresh produce, food storage, or processed seafood ultimately depends on a reliable and adequate energy supply. For most communities, diesel fuel is the primary source of power, which comes at high cost because of the logistics associated with importing the fuel to these relatively isolated communities. Integrating locally available renewable energy resources not only enhances energy supply, but the impacts further translate to food and water security in remote microgrids. The focus of this work is to investigate how intermittent renewable energy sources impact community level food and water infrastructure systems in a remote Arctic microgrid. Energy distribution models are mathematically developed in MATLAB® Simulink® to identify, describe, and evaluate the connections between intermittent renewable resources and the FEW loads. Energy requirements of public water systems, greenhouses, cold storage units, seafood processing loads, and modular water and food system loads are evaluated. Then energy sources including solar PV, solar thermal collectors, wind, hydro, energy storage, and diesel electric generation are modeled and validated. Finally, simulations of scenarios using distributed energy resources to serve water and food infrastructure loads are carried out including the incorporation of dispatchable loads. The results indicate that the impacts of renewable energy on FEW infrastructure systems are highly seasonal, primarily because of the variability of renewable resources. The outcome of this work helps in gaining firsthand insights into FEW system dynamics in a remote islanded microgrid setting.
    • Development of working fluid control techniques for improved ramping response in geothermal-based organic Rankine cycle generation systems

      Shofowora, Abayomi John; Wies, Richard; Denkenberger, David; Al-Badri, Maher (2021-05)
      Small-scale low-temperature geothermal-based electricity generation systems are under development for use as grid supporting and grid forming power sources in remote locations. Conversion of low-temperature heat to electrical energy in an organic Rankine cycle using working fluids such as refrigerants is challenging due to the low energy conversion efficiency of the process and the significantly slower thermal response rate in comparison to the time response of the electrical grid for changes in electrical generation and load. There is a need to investigate techniques for controlling the flow of the working fluid in combination with the use of a secondary heat exchanger to improve ramping response of these systems. This research project develops and models a working fluid control technique that incorporates power electronic technologies that could help to improve the ramping response of geothermal-based organic Rankine cycle generation systems. The performance of the model is examined with the aid of simulations in MATLAB® Simulink®. The results from these simulations are used to develop a functional and reliable control technique for ramping response improvement in geothermal-based electricity generation systems using organic Rankine cycles.
    • Drivers of life history variation in a long-lived, marine predator: individual heterogeneity in reproductive performance of grey seals (Halichoerus grypus)

      Badger, Janelle Jean; Breed, Greg; Bowen, W. Don; Doak, Pat; Mueter, Franz; Kitaysky, Alexander (2021-08)
      Fitness variation among individuals is a key tenet of eco-evolutionary theory, as natural selection acts upon this variation to bring about evolutionary change. Our understanding of individual heterogeneity and its evolutionary consequences in wild populations is limited, particularly for long-lived animals which are difficult to observe on a biologically relevant scales. This dissertation explores the dynamics of reproductive heterogeneity in a long-lived, iteroparous animal stemming from individual variation, energetic trade-offs, and ecological conditions using over 35 years of longitudinal data on a large sample of marked female grey seals (Halichoerus grypus) breeding on Sable Island, Nova Scotia. Using mixed-effects regression and novel mark- recapture techniques, I investigate three topics. First, I evaluated the evidence for and structure of individual heterogeneity in reproductive performance and determined how this heterogeneity interacts with increasing population size. In particular, I assessed whether population density affects individual-level reproduction, and may alter or amplify differences among individuals. Next, I investigated the relative contributions of individual heterogeneity and energetic trade-offs as drivers of life history variation by exploring the relationship between age-specific reproductive performance and survival. Finally, I determined how physical characteristics in early ontogeny may be a source for individual variation in reproductive success. Overall, I showed that individual heterogeneity is a prevalent and important feature of the Sable Island breeding population that interacts with ecological conditions. Variation among individuals in reproductive ability appears to be a main driver of variation in life history trajectories, and this variation may in part stem from physical characteristics and conditions during early ontogeny. These results have important implications for future demographic and ecological analyses on this population as it reveals that individual variation cannot be ignored to accurately estimate vital rates and underlying individual trade-offs. This work is one of few on long-lived marine mammals and may provide insights into drivers of life history variation of other systems of long-lived, iteroparous animals that are not so well observed.