• Natural histories of Yup'ik memoirs

      Crecelius, Caroline R.; Shoaps, Robin; Charles, Walkie; Plattet, Patrick (2017-12)
      This thesis explores how cultural knowledge is committed to textual form and circulated within and outside of linguistically marginalized communities. Working within a Central Yup'ik context, I have focused my research on collections of Yup'ik elders' memoirs housed within the Alaska Native Language Archive. Published Yup'ik elders' memoirs offer rich descriptions of Yup'ik cultural histories, epistemologies and statements about language, the expression and inclusion of which varies based on the interactional contexts, participant frameworks and funding institutions through which they were produced. This study incorporates both Indigenous and non-Indigenous theoretical frameworks related to the process of entextualization, or text creation, and the transmission of cultural knowledge. Drawing from archival materials and interviews with participants involved in their production and circulation, I identify the relevant linguistic ideologies and participant frameworks involved in the creation of these publications or "text artifacts" and frame my analysis with respect to the following research questions: How have published memoirs of Yup'ik elders emerged as a culturally salient genre of text? Who are the primary participants in the production, publication and circulation of Yup'ik memoirs? How do issues of identity, agency, authenticity and essentialism shape the form, thematic content and circulation of Yup'ik memoirs in Alaska? This thesis seeks to identify the primary participants and ideologies contributing to the publication of Yup'ik elders' memoirs, as well as the visibility or erasure of these actors within the published text of the memoirs. I further explore the specific ways in which individual voices, tribal, political and academic institutions and their ideological goals presuppose and contribute to broader cultural processes and shape the linguistic structure and content of textual artifacts produced. Although the documentation, description and analysis of Yup'ik language and culture has received sustained attention both within and outside the academy, this project is the first to investigate the processes and participant frameworks through which traditional Yup'ik cultural knowledge is entextualized and circulated as contemporary published text. This research offers significant insights into the collaborative efforts of Native and non-Native participants in the production of Yup'ik textual materials, while also contributing to a broader understanding of ideological goals and obstacles relative to processes of entextualization within communities facing marginalization or language endangerment within, and outside of, the circumpolar north. An analysis of the participants and ideologies shaping the production and circulation of Yup'ik memoirs provides and empirical framework for understanding the relationship between text artifacts and ongoing cultural processes, and contributes to an increasingly reflexive approach to anthropological and sociolinguistic research concerning identity, authenticity and the entextualization of traditional knowledge.
    • Nature-based tourism operator response to environmental change in Juneau, Alaska

      Timm, Kristin; Sparrow, Elena B.; Pettit, Erin C.; Taylor, Karen M.; Trainor, Sarah F. (2014-08)
      Increasing temperatures are projected to have a positive effect on the length of Alaska's summer tourism season, but the natural attractions that tourism relies on, such as glaciers, wildlife, fish, or other natural resources, may change. In order to continue to derive benefits from these resources, nature-based tour operators may have to adapt to these changes, and communication is an essential component of the adaptation process. The goal of this study is to determine how to provide useful climate change information to nature-based tour operators by answering the following questions: 1. What environmental changes do nature-based tour operators perceive? 2. How are nature-based tour operators responding to climate and environmental change? 3. What climate change information do nature-based tour operators need? To answer these questions, 24 nature-based tour operators representing 20 different small and medium sized businesses in Juneau, Alaska were interviewed. The results show that Juneau's nature-based tour operators are observing, responding to, and in some cases, actively preparing for changes in the environment. The types of environmental changes observed depended on the types of resources operators relied on and the way they accessed those resources, but a majority of the operators revealed that the loss of glaciers is a particularly large risk to their businesses and the tourism industry as a whole. Despite the observation of or perception of future risks, nearly a third of nature-based tour operators are not responding to changes in the environment. The remainder of nature-based tour operators were coping with environmental change, by changing their tour activities, expanding existing risk management activities, or participating more generally in conservation activities like recycling and fuel reduction. Only a few of the nature-based tour operators were planning for climate change, and taking strategic approaches to adaptation like including climate change in their business plans or creating a company task force. Using data about certainty in climate change information and the perceived risks to the organization, this study proposes a framework to classify climate change responses for the purpose of generating meaningful information and communication processes that promote adaptation or build adaptive capacity in the tourism sector. The results of this study demonstrate that science communication research has an important place in climate change adaptation and sustainability science.
    • Navigating the predator gauntlet: consumption of hatchery- and wild-born juvenile chum salmon (Oncorhynchus keta) by common nearshore marine fishes in Southeast Alaska

      Duncan, Douglas H.; Beaudreau, Anne H.; McPhee, Megan V.; Westley, Peter A. H. (2018-12)
      Juvenile chum salmon (Oncorhynchus keta) undergo extensive mortality at marine entry, a period which is believed to be a potential population bottleneck. Although this early mortality has been consistently observed, our understanding of the mechanisms responsible is limited. Furthermore, the implications of large-scale salmon hatchery releases for the ecology of juvenile chum salmon and their consumers is another important knowledge gap. To better understand the predation responses of abundant consumers to hatchery- and wild-born juvenile chum salmon, we examined the diets of Pacific staghorn sculpin (Leptocottus armatus) and Dolly Varden (Salvelinus malma) near Juneau, Alaska, in 2016 and 2017. Chum salmon composed 4.5% and 19.6% of the diets of staghorn sculpin and Dolly Varden by weight, respectively, and 88% of chum salmon individuals consumed were of hatchery origin. Chum salmon prey were shorter than average when compared to chum salmon concurrently collected by beach seine and hatchery releases of chum salmon. Regression analyses indicated that occurrence of juvenile chum salmon in diets varied primarily by date and site. Predation generally occurred more frequently at sites closer to hatchery release areas. The quantity of chum salmon in staghorn sculpin stomachs was related to predator length, chum salmon catch-per-unit-effort (CPUE), and the proportion of hatchery fish present; however, date was the only important predictor explaining quantity of chum salmon in Dolly Varden stomachs. To translate diet data into consumption rate, we experimentally determined gastric evacuation rate for staghorn sculpin and implemented a field-based consumption model. Average daily consumption of chum salmon was low relative to all other prey groups. Estimates of average seasonal consumption of juvenile chum salmon by staghorn sculpins suggest that predator populations would have to be implausibly large to consume even 1% of local hatchery chum salmon production. Together, these results yield new insights into the interactions between the predators of wild-born and hatchery-born salmon during the critical stage of marine entry.
    • NCPA propagation code users manual

      Winkelman, Andrew T.; Szuberla, Curt A.; Fee, David E.; Olson, John V. (2015-12)
      This manual was written for University of Alaska Fairbanks infrasound group to assist researchers in using the National Center for Physical Acoustics (NCPA) code suite to further investigate observed infrasonic phenomena. The NCPA code suite is designed to simulate various aspects of infrasound propagation through a model atmosphere. This suite was developed and tested by the University of Mississippi National Center for Physical Acoustics infrasound group. Included are raytrace routines to initially establish signal paths, both single frequency and broadband modal routines to calculate pressure fields and transmission losses, and a parabolic method to calculate pressure fields and transmission losses in model atmospheres.
    • Near-roadway air pollution: evaluation of fine particulate matter (PM₂.₅) and ultrafine particulate matter (PM ₀.₁) in Interior Alaska

      Kadir, Abdul; Aggarwal, Srijan; Belz, Nathan; Barnes, David; Mao, Jingqiu (2019-05)
      Particulate air pollution in the form of fine (PM₂.₅) and ultrafine (PM₀.₁) particles has become a global concern, especially in urban areas with high population and vehicular traffic. Considerable research has been carried out to understand the underlying processes that impact particulate pollution, but most studies have been conducted in warmer and urban regions such as in California. The Fairbanks North Star Borough (FNSB), in Interior Alaska, provides an interesting example of a relatively small- to mid-sized northern locality (population ~100,000) with persistent air quality issues and extremely cold climatic conditions for a major part of the year. Since December 2009, the FNSB has been designated a nonattainment region by the U.S. Environmental Protection Agency for the federal PM₂.₅ standard. As part of their remediation efforts, the borough and state have undertaken increased monitoring by using an on-roadway monitoring vehicle (sniffer vehicle) and stationary near-roadway sites for air quality measurements, beyond what is required for regulatory compliance. One of the goals of this project was to develop a novel data investigation and analyses methodology for the geospatial air quality data collected by the borough's mobile monitoring vehicle (years 2012-15), to shed light on the PM₂.₅ issues faced by the FNSB. In addition, this research also undertook measurements of ultrafine particle (UFP) concentration levels at four road weather information system (RWIS) sites in the FNSB region. UFPs, though unregulated, are considered to have significant human health impacts and no known studies have investigated UFPs in FNSB. In addition to UFPs, other parameters such as PM₂.₅, traffic, and weather data were measured at the same locations to investigate any underlying trends/correlations with UFPs. In the first part of the research with mobile monitoring, data were categorized in nine different groups based on their mean and standard deviation values to determine the spatiotemporal distribution of PM₂.₅. This novel way of grouping data allows identification of locations with consistently poor and consistently better air quality, by going beyond the simple analyses of means and accounting for variability and standard deviation in the data. In addition to hotspot identification, analyses found that average on-roadway PM₂.₅ concentrations were higher in North Pole (27.2 μg/m³) than in Fairbanks (12.9 μg/m³), and that average concentrations were higher in the background stationary monitoring data (29.4 μg/m³) than in the mobile monitoring data (20.0 μg/m³) for the study period. Not surprisingly, significant negative correlations (R² = 0.49 for Fairbanks, and R² = 0.31 for North Pole) were found between temperature and PM₂.₅. Temporal distribution of the data suggests that PM₂.₅ levels increase gradually in the months of October and November, peak during the months of December, January, and February, and quickly plummet beginning March. In the latter part of the study, data on UFP measurements were collected at four RWIS sites in the FNSB for four days between March 1 and 18, 2017, for five continuous hours each day. Among other parameters, PM₂.₅ concentrations, temperature, relative humidity, wind speed, and traffic volume data were collected. Data were analyzed to develop correlations between UFPs and other parameters, to compare data from this study with other studies, and to determine current roadside UFP concentration levels in interior Alaska. Fairbanks roadside locations showed higher mean UFP counts (41,700 particles/cm³) than the North Pole (22,100 particles/cm³) locations. Similarly, for the period of study, Fairbanks roadside locations showed higher PM₂.₅ concentrations and traffic counts (6.3 μg/m³; 15 vehicles/min) than the North Pole (4.6 μg/m³; 10 vehicles/min) locations, both being well below the on-roadway and background PM₂.₅ concentrations estimated in the first part of this report. Multilinear predictive models were developed for estimation of UFPs and PM₂.₅ based on weather and traffic parameters. This first study of UFPs in Alaska improves our understanding of near-roadway UFPs in cold regions.
    • Negotiating the languages of landscape: place naming and language shift in an Inupiaq community

      Marino, Elizabeth K. (2005-12)
      This thesis examines the correlations between language shift, language death, and cultural change through the use of place names in White Mountain, Alaska. Traditionally Inupiaq place names have served as descriptive tools for navigating the landscape and as memory markers for oral histories, taboos, and places of harvest. Local Inupiaq place names have been inscribed in social memory for generations and, according to Inupiaq elders in White Mountain, none are without significance. As English replaces the Inupiaq language, these traditional place names fall out of use, as well as the local histories and other information associated with them. English place names used today continue to inscribe information into the land, but of a different sort. This thesis finds that cultural change and cultural resiliency can be clearly observed through and are related to language shift in White Mountain. Included in this thesis are listings and maps of traditional Inupiaq place names from White Mountain, Alaska.
    • Neotectonic framework of the north-central Alaska Range foothills

      Bemis, Sean Patrick (2004-12)
      The northern foothills of the Alaska Range form a northward-convex salient at the apex of this orogen and the Denali fault. Despite the proximity of the northern foothills to the Denali fault and several historic large-magnitude earthquakes, the tectonic framework of this region has not been well-studied. A distinct pattern of east-trending folds and faults exists in both the bedrock and the geomorphic features. To assess the active structures of the region, I interpreted previous geologic mapping, developed cross-sections across the foothills belt, analyzed topographic and stream profiles, mapped the sequence of Quaternary fluvial terraces, and performed GPS transects across several terrace treads. A northward topographic slope across the northern foothills corresponding with the pattern of faulting and folding suggests the presence of an orogenic wedge overlying a south-dipping basal detachment. Mapping and GPS transects show evidence for progressive deformation of the terraces. Geomorphic analyses suggest deformation and differential uplift over the entire foothills belt. These results indicate that the northern foothills are an active fold-and-thrust belt and are prograding northward into the Tanana Basin. Tectonic activity of these structures suggests that this region represents a potential seismic hazard for nearby military facilities and important transportation corridors.
    • The neotectonics, uplift, and accommodation of deformation of the Talkeetna mountains, south-central Alaska

      Mixon, Demi C.; Hanks, Catherine; Nadin, Elisabeth; Beget, James (2016-08)
      South-central Alaska is home to many tectonic structures and mountain ranges that have experienced active uplift and deformation within the past 5 to 10 Ma. The Talkeetna Mountains are located above the area of flat-slab subduction of the Yakutat microplate. I hypothesize that the Talkeetna Mountains have been uplifted as a result of this underlying flat-slab subduction and that areas of the Talkeetna Mountains are neotectonically active. The Talkeetna Mountains are deforming heterogeneously across four different structural domains defined by differences in geomorphic patterns, seismicity, dominant fault types, and the orientation of horizontal maximum stress (SHmax). A strain partitioning structure divides the northern and southern domains, and is observed by a change in SHmax orientation from E-W in southern domains to NW-SE in the northern domain. The strain partition is accommodated by a crustal break along the Talkeetna thrust fault, which is expressed at the surface as a wide zone of deformation. Apatite fission-track analysis suggests two distinct periods of uplift: one dated from 45 to 30 Ma and another from approximately 10 Ma to present, with uplift rates of 0.14 mm/yr and 0.24 mm/yr, respectively. The first phase of uplift coincides with a time of significant plate reorganization in the north Pacific which resulted in translation of terranes northwestward. The second phase of uplift correlates with Neogene accretion of the Yakutat microplate. I propose that the majority of Neogene deformation and uplift in the Talkeetna Mountains is due to farfield deformation in the upper plate above the subducting slab. Variations in both composition of the crust and depth to the downgoing slab resulted in strain partitioning and northwest-directed compression in the northern Talkeetna Mountains and northwest compression and warping in the southern Talkeetna Mountains.
    • Nest -Building Behavior In House Mice (Mus Musculus), A Potential Model Of Obsessive -Compulsive Disorder In Humans

      Greene-Schloesser, Dana M.; Bult-Ito, Abel (2007)
      OCD (obsessive-compulsive disorder) is a chronic and debilitating psychiatric condition characterized by intrusive and persistent thoughts (obsessions) and repetitive behaviors (compulsions) that become ritualistic in an attempt to escape the obsessions. Currently there is a paucity of animal models with robust and spontaneous (non-drug or non-behaviorally induced) compulsive-like behaviors. This study is aimed at validating a novel robust and spontaneous genetic mouse model of OCD. The compulsive-like nest-building behavior in mice selected for high levels of nest-building behavior (BIG) has good face validity, with a behavioral phenotype that resembles hoarding behavior characteristic of OCD. In addition, male and female BIG mice displayed compulsivelike digging behavior relative to mice selected for low levels of nest-building behavior (SMALL), as assessed by the marble-burying test. Both chronic oral fluoxetine and clomipramine treatment reduced compulsive-like nest-building behavior in male BIG mice. Furthermore, chronic oral fluoxetine administration decreased nest-building behavior of BIG mice in a dose-dependent manner, while desipramine, an antidepressant not effective for treating OCD, did not significantly alter this behavior. The administration of fluoxetine did not cause a decrease in general locomotor behavior. These findings suggest that the nest-building phenotype has predictive validity. In addition, chronic oral fluoxetine treatment reduced compulsive-like digging behavior in male and female BIG mice as compared to SMALL mice. Gender effects were also found in treatment response. Clomipramine did not reduce nest-building in female BIG mice in a dose-dependent manner, which is consistent with previous studies. These data are in contrast to previous studies using BIG male mice which had a significant decrease in nest-building behavior with oral clomipramine. These results are consistent with studies on humans, which have found gender differences in the treatment effects of antidepressants. Additional construct validity is implicated by the results of targeted serotonergic lesions of the raphe nuclei in male BIG mice, which reduced repetitive nest-building behavior. More research is necessary to confirm the appropriateness of this model for human OCD; however, this model is promising based on the data that support good face, predictive and construct validity.
    • Nest and duckling survival of scaup at Minto Flats, Alaska

      Walker, Johann (2004-05)
      To address the hypothesis that declines in recruitment were related to recent declines in abundance of lesser and greater scaup, I estimated variation in nest and duckling survival of these species at Minto Flats, Alaska (64°50'N, 148°50'W) during 2002-2003. I included nest survival data from two previous studies conducted during 1989-1993 in my analysis. Daily Survival Rate (DSR) of nests was variable within and among years and among habitats. Estimated nest survival of scaup ranged from 0.02 (95% CI: 0.00 to 0.06) in 1992 to 0.61 (95% CI: 0.50 to 0.74) in 1993. Predation was the primary apparent cause of nest failure, and flooding of nests was an important secondary influence. DSR of ducklings varied between years and increased with age of the ducklings and body condition of the brood female. Duckling survival to 30 days was: 0.24 (95% CI: 0.16 to 0.36) in 2002 and 0.03 (95% CI: 0.00 to 0.19) in 2003. I conclude that high temporal variability in production of scaup at Minto Flats was likely related to annual variation in the risks of predation and flooding and indicated that intermittent years of high production could be particularly influential to this population.
    • Nesting biology of the spectacled eider Somatera fischeri (Brandt) on the Yukon-Kuskokwim Delta, Alaska

      Dau, Christian P. (1974-05)
      Nesting biology of the Spectacled Eider Somateria fischeri (Brandt) on the Yukon-Kuskokwim Delta, Alaska, was studied in 1972 and 1973. These data are compared with data from 1969, 1970, and 1971 (Eisenhauer et al. 1971, Eisenhauer and Frazer 1972, and Mickelson 1973). Paired, the birds arrived mostly from the north within a 3-4 day period in mid-May. Before 7 June, 80 percent of the nests were initiated. Located on islands, shorelines and peninsulas, most nests were within 7 feet of water. Rate of egg laying was 1/day (mean clutch size 4.5 eggs). Incubation lasted 24 days. Hatching took place from 20 June to 10 July (nesting success range 35 percent to 83 percent). Timing of nest site availability appears to dictate clutch size and reproductive success. Ducklings are raised on shallow freshwater ponds within 1.5 miles of their nest site.
    • Nesting ecology of ducks in interior Alaska

      Petrula, Michael J. (1994-09)
      This study represents one of the first intensive efforts to locate and monitor duck nests in interior Alaska. We located 263, 409 and 450 nests of 12 duck species on Minto Flats in 1989, 1990 and 1991,respectively. We conclude that habitat for breeding waterfowl cannot be considered stable in interior Alaska. Flooding reduced the availability of meadows which precluded ducks from nesting in high-water years despite their presence during the Breeding Pair Survey. Differences in the length of the breeding season and differential response to photoperiod between sub-Arctic and prairie nesting ducks suggest the potential for genetic differences between populations. Similar clutch sizes between high and mid-latitudes, however, suggest that ducks are able to compensate for the additional energetic costs associated with breeding at high latitudes. Flooding of meadow habitat and low nest success resulting from predation probably limit overall duck production on Minto Flats.
    • Nesting ecology of migratory golden eagles (Aquila chrysaetos) in Denali National Park, Alaska

      McIntyre, Carol L. (1995-12)
      Between 1988 and 1993 I measured occupancy of nesting territories and reproduction of golden eagles (Aquila chrysaetos) in Denali National Park, Alaska. I collected data occupancy of nesting territories and three reproductive variables (pairs nesting, pairs producing fledglings, and fledgling production) at 74 nesting territories using three aerial surveys each year. During my study, annual fledgling production varied nearly threefold, from 20 fledglings in 1992 to 58 fledglings in 1989. Although rates of nesting territory occupancy did not vary significantly among years (yj = 8.21, d.f. = 5, P = 0.114), I noted significant variation in the proportion of pairs laying eggs (X2 = 33.12, d.f. = 5, P < 0.001) and the proportion of pairs fledging young (X2 = 16.03, d.f. = 5, P = 0.007) among years. Decreases in pairs laying eggs were correlated with decreases in average daily numbers of snowshoe hare (Lepus americanus) and willow ptarmigan (Lagopus lagopus) observed in the study area (rs = 0.83, P = 0.04).
    • Networks of change: extending Alaska-based communication networks to meet the challenges of the anthropocene

      Hum, Richard E.; Taylor, Karen; Chapin, F. Stuart, III; Koskey, Michael; Brower, Pearl Kiyawn Nageak; Carlson, Cameron (2017-08)
      The Anthropocene is a contested term. As I conceptualize it throughout this dissertation, the Anthropocene is defined by an increased coupling of social and environmental systems at the global scale such that the by-products of human processes dominate the global stratigraphic record. Additionally, I connect the term to a worldview that sees this increased coupling as an existential threat to humanity's ability to sustain life on the planet. Awareness that the planet-wide scale of this coupling is fundamentally a new element in earth history is implicit in both understandings. How individuals and communities are impacted by this change varies greatly depending on a host of locally specific cross-scale factors. The range of scales (physical and social) that must be negotiated to manage these impacts places novel demands on the communication networks that shape human agency. Concern for how these demands are being met, and whose interests are being served in doing so, are the primary motivation for my research. My work is grounded in the communication-oriented theoretical traditions of media ecology and the more recent social-ecological system conceptualizations promoted in the study of resilience. I combine these ideas through a mixed methodology of digital ethnography and social network analysis to explore the communication dynamics of four Alaska-based social-ecological systems. The first two examples capture communication networks that formed in response to singular, rapid change environmental events (a coastal storm and river flood). The latter two map communication networks that have formed in response to more diffuse, slower acting environmental changes (a regional webinar series and an international arctic change conference). In each example, individuals or organizations enter and exit the mapped network(s) as they engage in the issue and specific communication channel being observed. Under these parameters a cyclic pattern of network expansion and contraction is identified. Expansion events are heavily influenced by established relationships retained during previous contraction periods. Many organizational outreach efforts are focused on triggering and participating in expansion events, however my observations highlight the role of legacy networks in system change. I suggest that for organizations interested in fostering sustainable socialecological relationships in the Anthropocene, strategic intervention may best be accomplished through careful consideration of how communicative relationships are maintained immediately following and in between expansion events. In the final sections of my dissertation I present a process template to support organizations interested in doing so. I include a complete set of learning activities to facilitate organizational use as well as examples of how the Alaska Native Knowledge Network is currently applying the process to meet their unique organizational needs.
    • Neural control of singing in the dark-eyed junco (Junco hyemalis)

      Gulledge, Cynthia Corbitt (1997)
      This dissertation includes several discrete projects addressing various aspects of the neural control of singing in the Dark-eyed Junco (Junco hyemalis), a migratory songbird. I collected the birds from a local wild population during the breeding season and migration. Chapter 2 addresses the role of testosterone in controlling volumes of the brain regions that control song learning and song production (vocal control regions, VCRs), which grow and shrink seasonally and are correlated with changes in singing behavior. I found that: the role testosterone plays may depend on the age of the bird and the brain region in question. Expanding on that study, I investigated the independent roles of testosterone and photoperiod in the control of VCR volumes in adolescent male juncos (Chapter 3). In seasonally breeding species, circulating androgens increase with increasing photoperiod, so increases in VCR volumes in the spring had been thought to be a result of photoperiod-induced increases in testosterone. Experimental separation of photoperiod and testosterone revealed that long photoperiod alone can have stimulatory effects on VCR growth, despite low testosterone levels. In fact, in adolescent male juncos, lengthening photoperiod may play a greater role in determining VCR volumes than testosterone does, again suggesting that the role of testosterone in the vocal control system may change with age. Other neurochemicals besides testosterone are present in the vocal control system; Chapter 4 describes the first description of opioid peptide receptor localization and density measurement in the vocal control system of adult male songbirds. I expanded that study to include nonsinging female and juvenile juncos (Chapter 5). The results of the expanded study indicate that opioids may modulate development of the vocal control system between adolescence and adulthood, as well as auditory processing throughout life.
    • Neural Network Approach To Classification Of Infrasound Signals

      Lee, Dong-Chang; Szuberla, Curt (2010)
      As part of the International Monitoring Systems of the Preparatory Commissions for the Comprehensive Nuclear Test-Ban Treaty Organization, the Infrasound Group at the University of Alaska Fairbanks maintains and operates two infrasound stations to monitor global nuclear activity. In addition, the group specializes in detecting and classifying the man-made and naturally produced signals recorded at both stations by computing various characterization parameters (e.g. mean of the cross correlation maxima, trace velocity, direction of arrival, and planarity values) using the in-house developed weighted least-squares algorithm. Classifying commonly observed low-frequency (0.015--0.1 Hz) signals at out stations, namely mountain associated waves and high trace-velocity signals, using traditional approach (e.g. analysis of power spectral density) presents a problem. Such signals can be separated statistically by setting a window to the trace-velocity estimate for each signal types, and the feasibility of such technique is demonstrated by displaying and comparing various summary plots (e.g. universal, seasonal and azimuthal variations) produced by analyzing infrasound data (2004--2007) from the Fairbanks and Antarctic arrays. Such plots with the availability of magnetic activity information (from the College International Geophysical Observatory located at Fairbanks, Alaska) leads to possible physical sources of the two signal types. Throughout this thesis a newly developed robust algorithm (sum of squares of variance ratios) with improved detection quality (under low signal to noise ratios) over two well-known detection algorithms (mean of the cross correlation maxima and Fisher Statistics) are investigated for its efficacy as a new detector. A neural network is examined for its ability to automatically classify the two signals described above against clutter (spurious signals with common characteristics). Four identical perceptron networks are trained and validated (with >92% classification rates) using eight independent datasets; each dataset consists of three-element (each element being a characterization parameter) feature vectors. The validated networks are tested against an expert, Prof. Charles R. Wilson, who has been studying those signals for decades. From the graphical comparisons, we conclude that such networks are excellent candidate for substituting the expert. Advantages to such networks include robustness and resistance to errors and the bias of a human operator.
    • Neural-Network Modeling Of Placer Ore Grade Spatial Variability

      Ke, Jinchuan; Bandopadhyay, Sukumar (2002)
      Traditional geostatistical methods have been used in ore reserve estimation for decades. Research in the last two decades or so has added a number of other statistical methodologies for ore reserve estimation procedures. Recent advances in neural networks have provided a new approach to solve this problem. This thesis is focused on the Neural-network modeling for the estimation of placer ore reserve. Due to the spatial variability, multiple dimensional inputs and very noisy drill hole sample data from the selected region, it requires that the neural-network be organized in a multiple-layers to handle the non-linearity and hidden slabs for smoothing the predicted results. Various neural-network architectures are investigated and the Back-propagation is selected for modeling the ore reserve estimation problem. Sensitivity analysis is performed for the following parameters: the type of neural-network architecture, number of hidden layers and hidden neurons, type of activation functions, learning rate and momentum factors, input pattern schedule, weight updated, and so on. The influences of these parameters on the predicted output are analyzed in details and the optimal parameters are determined. To investigate the accuracy and promise of neural network modeling as a tool for ore reserve estimation, the ore grade and tonnage of Neural-network output is compared with those estimated by geostatistical methods under various cut-off grades. In addition, the overall performance is also validated by the analysis of R-squared (R2), Root-Mean-Squared (RMS), and the comparison between predicted values and 'actual' values. As the final part of this study, the optimized Neural Network was used to estimate the distribution of placer gold grade and volume of gold resource in offshore Nome. The predicted results for all the mining blocks in the lease area are validated by checking the values of RMS, R2, and Scatter plots. The estimated gold grades are also presented as contour maps for visualization.