• UAF's light-duty vehicle fleet lifecyle, maintenance costs and composition: ordinary least square regression and panel data analysis

      Hix, Edward R.; Wright, Christopher; Baek, Jungho; Little, Joe; Goering, Greg; Platt, Nathan (2020-08)
      The University of Alaska Fairbanks maintains a vehicle fleet for use by its staff, faculty, and students. Given the multifaceted needs of the campus and the impact that the harsh subarctic climate can have on vehicles, management of the fleet to meet the needs of its users is a complex task. One method UAF uses to manage the cost of the fleet is to extract the depreciation expense from each fleet vehicle into a non-interest bearing recharge account to eventually purchase its replacement. While several reviews have been conducted regarding the management of this fleet, a gap in research involves analysis of cost of this fleet over its lifecycle. This study examined the effects of fleet vehicle lifecycle extension beyond the predetermined 10-year useful life at UAF. Three novel datasets were created from UAF Facilities Services' archival maintenance work order data: a vehicle dataset, work order dataset, and a panel dataset. Ordinary least squares regression methods were used to examine the impact of model year on a vehicle's nominal purchase price and the impact of vehicle specification on real purchase price. Fixed and random effects panel methods were used to examine the impact of vehicle specification and vehicle age on maintenance costs. The effects of extending the fleet lifecycle from ten to twenty-years on maintenance and operational cost were estimated. Population dynamics models estimated the impact of the ten year lifecycle extension on the replacement fund. The results of this study suggested increasing vehicle lifecycles by ten years increased operating, maintenance, and replacement costs and effectively reduced the replacement fund purchasing power. The extension of vehicle lifecycles resulted in continually increasing rental rates and ultimately to the insolvency of the replacement fund.
    • Uncertainty quantification in unconventional reservoirs using conventional bootstrap and modified bootstrap methodology

      Okoli, Chukwuemeka; Awoleke, Obadare; Goddard, Scott; Ahmadi, Mohabbat (2020-12)
      Various uncertainty quantication methodologies are presented using a combination of several deterministic decline curve analysis models and two bootstrapping algorithms. The bootstrapping algorithms are the conventional bootstrapping method (CBM) and the modied bootstrapping method (MBM). The combined deterministic-stochastic combination models are applied to 126 sample wells from the Permian basin. Results are presented for 12 to 72 months of production hindcast given an average well production history of 120 months. Previous researchers used the Arps model and both conventional and modied bootstrapping with block re-sampling techniques to reliably quantify uncertainty in production forecasts. In this work, we applied both stochastic techniques to other decline curve analysis models∎namely, the Duong and the Stretched Exponential Production Decline (SEPD) models. The algorithms were applied to sample wells spread across the three main sub-basins of the Permian. A description of how both the deterministic and stochastic methods can be combined is provided. Also, pseudo-codes that describes the methodologies applied in this work is provided to permit readers to replicate results if necessary. Based on the average forecast error plot in the Permian Basin for 126 active wells, we can also conclude that the MBM-Arps, CBM-Arps, and MBM-SEPD combinations produce P50 forecasts that match cumulative production best regardless of the sub-basin and amount of production hindcast used. Regardless of concerns about the coverage rate, the CBM-Arps, MBM-Arps, CBM-SEPD, and MBMSEPD algorithm combinations produce cumulative P50 predictions within 20% of the true cumulative production value using only a 24-month hindcast. With a 12 month-hindcast, the MBM-Arps combined model produced cumulative P50 predictions with a forecast error of approximately 20%. Also, the CBM-SEPD and MBM-SEPD models were within 30% of the true cumulative production using a 12- month hindcast. Another important result is that all the deterministic-stochastic method combinations studied under-predicted the true cumulative production to varying degrees. However, the CBM-Duong combination was found to severely under-predict cumulative production, especially for the 12-month hindcast. It is not a suitable model combination based on forecast error, especially when hindcast fractions on the low end of the spectrum are used. Accordingly, the CBM- Duong combination is not recommended, especially if production history of no more than 24 months is available for hindcasting. As expected, the coverage rate increased, and the forecast error decreased for all the algorithm combinations with increasing hindcast duration. The novelty of this work lies in its extension of the bootstrapping technique to other decline curve analysis models. The software developed can also be used to analyze many wells quickly on a standard engineering computer. This research is also important because realistic estimates of reserves can be estimated in plays like the Permian basin when uncertainty is correctly quantied.
    • Utility of trace element studies for improving our understanding of geochemical processes within the arctic ocean environment

      Bolt, Channing; Aguilar-Islas, Ana; Rember, Robert; Reynolds, Jennifer; Rivera-Duarte, Ignacio; Simmons, Harper (2021-05)
      The Arctic Ocean is a dynamic region undergoing rapid change. Sea ice and meteoric water are intrinsic components of the Arctic environment that play key roles in its ecosystem, including the distributions and cycling of trace elements throughout the pan-Arctic Ocean. Meteoric water (e.g., rivers and snow deposition) contributes to the input of trace elements to surface waters, while sea ice dynamics contribute to the transport of these constituents across Arctic basins. Trace element distributions can provide insights into Arctic processes. The focus of Chapter One is on particulate (>0.2 μm) trace elements in Arctic pack ice, associated snow, and underlying surface waters collected from September-October 2015 during the US GEOTRACES Western Arctic cruise (GN01). This late-season pack ice provides a snapshot of sea ice characteristics in regions near the North Pole, within the Makarov and Canada Basins, and can estimate the impact melting sea ice may have on particulate trace element inputs to Arctic waters. Chapter Two presents on the utility of dissolved barium (dBa), a bio-intermediate element of lithogenic origin, as a tracer of meteoric water throughout the Siberian Arctic Ocean. Samples for Chapter Two were collected during the 2018 Nansen and Amundsen Basin Observatory System. The distribution of dBa in this region may provide useful insights into important shelf processes, such as tracing shelf waters along continental slopes. In Chapter 3, additional spatiotemporal geochemical parameters (δ¹⁸O and salinity) are considered alongside dBa to model how Arctic water mass fractions (meteoric, sea ice melt, and Atlantic waters) changed between 2013, 2015, and 2018 within the Siberian Arctic Ocean. This dissertation contributes to the understanding of Arctic Ocean processes through the application of trace element studies and highlights the usefulness of combining tracers to better understand this dynamic environment.
    • Vertebrate ichnology and paleoenvironmental associations of Alaska's largest dinosaur track site in the cretaceous Cantwell Formation (Maastrichtian) of Denali National Park and Preserve

      Stewart, Dustin G.; Druckenmiller, Patrick; Fowell, Sarah; McCarthy, Paul (2020-10)
      The Upper Cretaceous Cantwell Formation in Denali National Park and Preserve (DENA) has recently been recognized as a major high latitude dinosaur track-bearing unit in Alaska. The abundant trace fossil record of the Cantwell Formation, which represents a diverse community of avian and non-avian dinosaurs, compliments the body fossil record of the state's other major dinosaur-producing unit, the Prince Creek Formation of northern Alaska. However, research in the Cantwell Formation is still in its infancy due to its wide aerial extent and remoteness, and many questions remain concerning the temporal, ichnological, and paleoenvironmental relationships of the formation. Here I describe and analyze the largest known single track site currently known in DENA and all of Alaska -- a football field-sized outcrop named the Coliseum. This site is composed of 65+ meters of vertical section, with laterally extensive fine- to medium-grained sandstone, indurated mudstone, fissile shale, and bentonite. Trace fossils at the Coliseum include true tracks, undertracks, natural casts, and trackways that vary in their preservation from eroded, trampled surfaces to individual prints with skin impressions. The tracks were documented via handheld and UAV-assisted photogrammetry, enabling a large-scale 3-dimensional mapping of the Coliseum. Facies analysis of the site reveal the tracks were formed on crevasse splay and overbank deposits within a fluvial floodplain. U-Pb dating of zircons collected from a bentonite horizon return an age of 69.3±0.9 Ma (early Maastrichtian), improving the temporal constraints of the formation and revealing one of the youngest ages of deposition for the formation. Several new dinosaurian ichnotaxa previously unrecognized from the formation are described, revealing the presence of large-bodied ornithopods, ceratopsids, and non-avian and avian theropod trackmakers. The Coliseum provides a snapshot of an ancient forested environment inhabited by a diverse dinosaurian community deposited in the Late Cretaceous paleo-Arctic.
    • Western Gwich'in classificatory verbs

      Bushey, Scott T.; Tuttle, Siri; Peter, Hishinlai'; Vajda, Edward (2021-05)
      One of the many challenges faced by learners and teachers of Gwich'in, an endangered Athabascan or Dene language of Alaska and Canada, is a lack of instructional material for classificatory verbs. These verbs classify states and actions, such as lie, carry, and fall, by perceived qualities, such as cloth-like and stick-like, that indicate how and with which nominal entities the state or action takes place. For students of Gwich'in and other Dene languages, such as Navajo and Koyukon, classificatory verbs are an important grammar objective when included in the curriculum. Recognition and production of classificatory verbs is a main objective for students in the second year of the UAF Gwich'in class. Classificatory verb words are also present in vocabulary learned from the first year, such as gishreiin'ąįį "it's sunny" and OBJ naltsuu "I'm wearing OBJ [upper-body garment]". In this thesis I present a documentary, descriptive study of classificatory verbs and their qualities in modern spoken Gwich'in. The first goal of the study is to document examples of Gwich'in classificatory verbs in conversational and narrative discourse, and the second is to describe their morphosemantic properties and behavior. The third goal is to accomplish these documentary and descriptive aims in a way that can be adapted readily to the needs of not only linguists, but also Gwich'in language learners and teachers. Informed by previous documentary and descriptive work on classificatory verbs in other Dene languages, I attempt to provide a similarly useful text for Gwich'in, reconciling several competing nomenclatures and illustrating the relationship between classificatory verb theme sets, such as "carry", and semantic classes of verb stems, such as "animate", in a broad range of modal and aspectual contexts. Although this thesis is intended primarily as a reference work for learners and teachers, it also provides a resource for linguists comparing Gwich'in classificatory verbs with those in related Dene languages. The classificatory verb data in this thesis is drawn from a body of Gwich'in class notes and assignments, well as transcribed Gwich'in oral literature and consultation with a native speaker of the language. Classroom instruction took place between 2018 and 2020 at the University of Alaska Fairbanks and emphasized spoken language production with communicative aims. In addition to work from the Gwich'in language classroom, limited native speaker consultation regarding classificatory verbs was also conducted in February 2020. The third data source for this study is the rich body of narrative discourse available in the form of transcribed oral literature. These works record Gwich'in traditional narrative knowledge, lore, and history across a broad range of topics, in which classificatory verbs may be readily encountered and examined. Having drawn from these three pools of data, this thesis describes the morphosemantic qualities of Gwich'in classificatory verbs while considering the available data on other Dene languages and considers actual and potential application of this data in the language classroom.
    • Widespread capacity for denitrification in soils, streams, and thermokarst lakes of boreal Alaska

      Burnett, Melanie S.; Harms, Tamara K.; Ruess, Roger W.; Walter Anthony, Katey M. (2021-05)
      Rapid warming in Alaska is causing permafrost to thaw, especially in the region of discontinuous permafrost, where soil temperatures may only be a few degrees below 0 °C. An intensifying fire regime may also be exacerbating permafrost thaw with more frequent and severe fires removing insulating organic layers above permafrost. Permafrost thaw releases carbon and nitrogen (N) into the actively cycling pools, and whereas carbon emissions following permafrost thaw are well documented, the fates of N remain unclear. Denitrification and release of nitrous oxide (N₂O) or nitrogen gas (N₂) could result in N loss from ecosystems, but the contributions of these processes to the high-latitude N cycle remain uncertain. I quantified microbial capacity for denitrification and nitrous oxide production in boreal soils, lakes, and streams, and assessed correlates of denitrifying enzyme activity in interior Alaska to determine if denitrification could contribute significantly to N loss from the boreal forest. Across all landscape positions, median potential denitrification rate under anoxic conditions with nitrate and organic carbon amendment was 4.15 [mu]g N₂O-N /kg dry soil*h (range -6.39 to 479.94). Denitrification potential was highest within and along streams in both sediments and adjacent riparian soils, upland soils were intermediate, and lakes supported lower rates, whereas deep permafrost soils supported little denitrification. Time since last burn had no effect on denitrification potential in upland soils. Across all landscape positions, denitrification potential was negatively correlated with ammonium pools. In lakes, potential rate of denitrification declined with sediment depth, and was positively driven by organic matter content. In this era of anthropogenic climate change, pervasive N loss to denitrification in the boreal forest could constrain the capacity for N-limited primary producers to preserve carbon stocks in soils following permafrost thaw.
    • The Yup'ik relationships of qiluliuryaraq (processing intestine)

      Carrlee, Ellen; Schweitzer, Peter; Koester, David; Lee, Molly; Hill, Erica; Plattet, Patrick (2020-12)
      This project explores multiple Native cultural contexts that intersect in the use and understanding of intestine. Gut (tissues of internal organs including stomach, intestine, bladder and esophagus) as a raw material was historically used by many circumpolar cultures to make items like drums, raincoats, hats, windows, sails, containers, and hunting floats. These items are abundant in museum collections, but rarely seen today in cultural practice or the art market. Intestine is a natural material that was replaced by synthetic materials, but its dual physical properties of protection and permeability are the only features replicated by plastics. Examination of intestine as an obsolete material reveals both changes and resilience in different kinds of relationships. Emphasizing the meaning and materiality of gut over analysis of artifacts made from it emphasizes interactions among human, animal, and spiritual beings over formalistic approaches privileging object interpretations. Preferential investigation of a raw material over finished artifacts focuses the study on actions and values in Native places. Fieldwork components for this study include documentation of indigenous gut processing, sewing and repair workshops in museum contexts, processing fresh intestine in the Yup'ik village of Scammon Bay, and discussion of gut with Yup'ik cultural experts. The theoretical approach uses Actor-Network Theory (ANT) as a foundation, animated with practice theory and relational ontology. Since ANT creates space for human, animal, and object agency, reciprocal relationships among these actors will be explored through frameworks of materiality, object biography, gender studies, animal personhood, and the gift. This endeavor may promote a new model for the use of material culture to illuminate Native values. In the case of intestine, its decline in use connects to changes in technology and spirituality while resilience and revitalization of gut technology promotes identity and demonstrates traditional values.
    • Zooplankton community composition in relation to environment and juvenile salmon diets in Icy Strait, Southeast Alaska

      Fergusson, Emily A.; Eckert, Ginny; McPhee, Megan; Heintz, Ron (2020-12)
      Zooplankton in the nearshore marine habitat function as an important prey resource for many pelagic fishes, are a major component of the lower tropic level, and serve as a vital ecosystem indicator. Understanding how the zooplankton community changes in response to fluctuations in biophysical factors is critical in a changing climate and is important to understanding the dynamics of commercially important upper-trophic level species that depend nutritionally on zooplankton. The Alaska Fisheries Science Center's Southeast Coastal Monitoring project has surveyed the pelagic ecosystem in eastern Icy Strait monthly from May to August since 1997 to understand how environmental variation affects the pelagic food web and the sustainability of salmon resources. I used this long-term dataset (1997-2017) to address the goals of this study: 1) to investigate the influence of temperature on the Icy Strait zooplankton community; and 2) to understand how juvenile salmon utilize zooplankton prey in relation to temperature driven fluctuations in the zooplankton community. In Chapter 1, I noted that the composition of the zooplankton community varied in years with anomalously high or low temperatures. I observed shifts in the timing of development in many key taxa during these anomalous years. For example, in anomalously cool years, several taxa were found in higher densities later in the summer than in anomalously warm years. In Chapter 2, I examined how oceanographic factors influenced the diet composition and quality of four species of juvenile Pacific salmon (Oncorhynchus spp.) in Icy Strait (Southeast Alaska) from 2013 to 2017. In 2015 I observed a change in diets, including zooplanktivorous (pink salmon O. gorbuscha, chum salmon O. keta, and sockeye salmon O. nerka) and piscivorous (coho salmon O. kisutch) species, from typically diverse diets to diets dominated by euphausiids. This year was notable for warm waters, deep pycnoclines, and below average zooplankton nutritional quality. Juvenile salmon appeared to supplement their lipid intake and meet nutritional requirements by switching to larger euphausiid prey. The results from these studies increase our understanding of zooplankton community dynamics, salmon trophic relationships, and the resilience and flexibility of the food web during climate-driven reorganizations of the pelagic marine ecosystem.