• A Sounding Rocket Attitude Determination Algorithm Suitable For Implementation Using Low Cost Sensors

      Charlton, Mark Christopher; Hawkins, Joseph G. (2003)
      The development of low-cost sensors has generated a corresponding movement to integrate them into many different applications. One such application is determining the rotational attitude of an object. Since many of these low-cost sensors are less accurate than their more expensive counterparts, their noisy measurements must be filtered to obtain optimum results. This work describes the development, testing, and evaluation of four filtering algorithms for the nonlinear sounding rocket attitude determination problem. Sun sensor, magnetometer, and rate sensor measurements are simulated. A quatenion formulation is used to avoid singularity problems associated with Euler angles and other three-parameter approaches. Prior to filtering, Gauss-Newton error minimization is used to reduce the six reference vector components to four quaternion components that minimize a quadratic error function. Two of the algorithms are based on the traditional extended Kalman filter (EKF) and two are based on the recently developed unscented Kalman filter (UKF). One of each incorporates rate measurements, while the others rely on differencing quaternions. All incorporate a simplified process model for state propagation allowing the algorithms to be applied to rockets with different physical characteristics, or even to other platforms. Simulated data are used to develop and test the algorithms, and each successfully estimates the attitude motion of the rocket, to varying degrees of accuracy. The UKF-based filter that incorporates rate sensor measurements demonstrates a clear performance advantage over both EKFs and the UKF without rate measurements. This is due to its superior mean and covariance propagation characteristics and the fact that differencing generates noisier rates than measuring. For one sample case, the "pointing accuracy" of the rocket spin axis is improved by approximately 39 percent over the EKF that uses rate measurements and by 40 percent over the UKF without rates. The performance of this UKF-based algorithm is evaluated under other-than-nominal conditions and proves robust with respect to data dropouts, motion other than predicted and over a wide range of sensor accuracies. This UKF-based algorithm provides a viable low cost alternative to the expensive attitude determination systems currently employed on sounding rockets.
    • African rooster

      Lybrook, Christian David (2001-05)
      'African Rooster' takes place in Lesotho, a tiny country surrounded by South Africa at a time of considerable tension. In 1994, South Africa is in the infancy of its democracy and Lesotho is thrown into turmoil with its own coup d'état. John David ("Jed") Kendall, a white, middle-class American, is thrown into this world as a nominal missionary balancing his own cultural and moral baggage with African sensibilities. My first choice of first person narrative allows for an examination of racial and cultural questions in African society without my narrator having to assume an air of authority that a third person might convey. It also allows more sympathy with Jed's sometimes unsympathetic character. Thematic notions of loyalty, justice, and racism propel the principal relationship between Jed/Senate and his 'brother, ' Tsediso. Their interactions become the primary vehicle for examining cultural, racial, and moral conflicts within Jed
    • Application of molecular markers to mixed-stock analysis of Yukon River fall chum salmon

      Flannery, Blair G. (2004-05)
      Country of origin provides the basis for allocating harvests of Yukon River chum salmon. The genetic divergence among Yukon River chum salmon populations adjacent to the international border as revealed by allozyme and micro satellite variation is insufficient to determine the country of origin of returning fish using mixed-stock analysis (MSA). Consequently, we investigated the resolution provided by alternative genetic markers in an attempt to detect levels of divergence that would be sufficient for MSA. We analyzed 10 Yukon River chum salmon populations for variation at 30 variable amplified fragment length polymorphism (AFLP) loci and for mitochondrial DNA (mtDNA) restriction site variation. We assessed these markers for their utility in MSA and, for mtDNA, phylogeographic analysis. The AFLP results show that MSA was most successful when mixtures were allocated to regions. The AFLP data were able to provide improved country of origin MSA estimates for the border populations with a 6.5% improvement for the Canadian populations over micro satellite analysis. No divergence in mtDNA haplotype frequency distributions was detected (P>0.05) within the Yukon River. Lack of mtDNA divergence likely resulted from a Pleistocene bottleneck that led to panmixia of the mtDNA genome.
    • Assessment of the reproductive ecology of harbor seals (Phoca vitulina) and northern sea otters (Enhydra lutris kenyoni) in Alaska using subsistence biosampling programs

      Hutchinson, Emily A.; Atkinson, Shannon; Hoover-Miller, Anne; Kruse, Gordon; Wynne, Kate (2014-08)
      Harbor seals (Phoca vitulina) and northern sea otters (Enhydra lutris kenyoni) in Alaska have experienced extreme fluctuations in abundance in recent decades. The purpose of this study was to examine growth and determine the age and size at sexual maturity in populations of these two species, as spatial and temporal variations in environmental conditions and changes in ecological constraints as a result of population fluctuations can influence growth and reproductive characteristics of individuals. All samples for this research were collected via biosampling, the collection of measurements and biological tissue samples, as a component of subsistence harvesting by Alaska Natives. In Chapter 1, morphometric measurements and reproductive tracts were collected by the Alaska Native Harbor Seal Commission's Biosampling Program from female harbor seals harvested throughout the Gulf of Alaska from 1998 through 2005. Seals attained an asymptotic standard length (SE) of 147.7 ± 2.6 cm and body mass of 82.2 ± 4.8 kg. Female harbor seals did not mature until a minimum age of 3 yr, a standard length of 122 cm, and a weight of 48 kg. The average age of sexual maturity was 4.2 ± 0.7 yr (95% CI). Fetal growth was measured by standard length, curvilinear length, axillary girth, the cube root of fetal mass, skull length, condylobasal length, zygomatic width, and skull width against the day of the year the mother was harvested. The x-intercept of the linear regression of each fetal growth measurement against the day of the year produced estimates of the implantation date that ranged from September 22nd to October 17th, with a mean date of September 30th ± 8 d (SD). Harbor seals from this study are smaller in length, have a later implantation date, and are larger at sexual maturity compared to harbor seals in the Gulf of Alaska from the 1960s. In Chapter 2, morphometric measurements and reproductive tracts were collected by a Native Alaskan subsistence hunter from 40 male sea otters near Gustavus, in Southeast Alaska. The maximum recorded standard length and axillary girth were 160 cm and 78.7 cm, respectively. Sexual maturity was assessed by the histological examination of the testes and epididymides and the subsequent measurement and characterization of the seminiferous tubules. Male sea otters in the region reached sexual maturity at 3 to 4 yr of age, after attaining a standard body length of 130 cm., a mean seminiferous tubule diameter of 140 µm, and a baculum length of 14 cm. Sea otters outside Gustavus, Alaska exhibit increased body size and lower ages of sexual maturity compared to sea otters in other regions of Alaska, suggesting that resources are abundant and are not limiting maturation rates of male sea otters near Glacier Bay. In the future, as anthropogenic influences continue to increase and environmental conditions fluctuate, biosampling programs will be an invaluable tool for continued monitoring of marine mammals in Alaska.
    • Automated processing system for tidal analysis of MF radar winds

      Vemula, Sreenivas (2005-12)
      The medium frequency (MF) radar at Platteville, Colorado (40.18° N, 104.7° W) is used to estimate the zonal and meridional wind motions in the middle atmosphere. This radar has been in operation since January 2000. We currently have four years of wind estimates sampled every five minutes. An automated processing system has been developed in IDL to process these estimates and obtain the monthly mean winds and tidal parameters. The automated processing currently processes the wind estimates in time domain analysis using a least square fitting technique. The criteria for determining when the estimated tidal parameters are valid have been studied along with the error analysis of the data and processing. The diurnal and semidiurnal parameters are obtained using this least square fitting method and these tidal parameters are assumed to be valid only when the condition number is less than 10. In the spectral domain, the fast Fourier transform and Lomb-Scargle periodogram methods have been studied. A test signal is generated and its performance using both FFT and Lomb-Scargle methods are discussed for three different cases which are equivalent to our actual data. The results of the wind estimates from 2000-2003 collected using the MF radar have been processed using the automated processing system. This automated processing system can be used to generate the wind parameters on a 24 hour, 7 day a week basis for an elaborate study. Our data are compared with MF radar data from Saskatoon, Canada and Urbana, lllinois. Most of the time our data are similar to the behavior of GSWM-02 model.
    • The average American

      Stolz, A. Digger (2004-08)
      'The Average American' is a screenplay crafted in the modern, mixed-genre tradition. Both comedic and dramatic elements are woven into a road movie structure. At its core, 'The Average American' questions the purpose and power of literature and explores how our society values the written word. This exploration is important because advances in technology and media increasingly threaten literature's place as a tool of communication. The protagonist, Art Spender, a disillusioned literary agent, journeys across the American Midwest in search of a mysterious writer whose brilliant new novel has piqued the interests of a New York publishing house. Ultimately, through interactions with various Americans during his journey into the heartland, Art discovers reasons to continue wading through the countless manuscripts that inundate his day to day existence.
    • Between us

      Mulcrone, Katherine Jean (2005-05)
      Between Us is the first-person account of Louise Halsey's return to her childhood home after her brothers' tragic motorcycle accident. Her brother Danny lies unconscious, but the strength of their bond grants Louie unexpected encounters with him inside the family home. Her conversations with Danny force Louie to reconsider the issues that have driven her family apart and her role in them. The novel begins with a series of vivid dreams which disconcert Louie and lay the groundwork for her to begin piecing together the unraveling of her family. Current sentiments as expressed and relationships as presented in Louie's conversations with family members are echoed by her memories of past events. Danny's death leads Louie to acknowledge that although rebuilding her family requires difficult work, it is work worth doing.
    • Border patrol

      Iseri, Erica Keiko (2000-12)
      'Border Patrol deals with people across geographical as well as cultural and linguistic lines.' So reads a sentence from the penultimate story of this thesis. While the main characters are all either Japanese or Japanese-American, and they live in Japan or Southern California or Fairbanks, Alaska, the stories explore such universal issues of love, obligation, and freedom. The characters' ethnicity and place serve mainly to inform the larger themes. The point of view from which the stories are told varies from story to story, from a young third person female to a middle-aged first person male. The amount of time in which the stories take place differs as well, from minutes to decades. The stories themselves, though, concern the characters' struggle for independence from constricting relationships and a search for identity through a passion--golf, music, origami. The line between dependence and inner strength is the border that they walk.
    • Breeding ecology of white-winged scoters on the Yukon Flats, Alaska

      Safine, David Elliot (2005-08)
      Breeding bird surveys indicate a long-term decline in the numbers of scoters (Melanitta sp.) in North America. My objectives were to estimate survival of nests, ducklings, and adult female White-winged Scoters (Melanitta fusca) breeding on the Yukon Flats National Wildlife Refuge, Alaska, 2002-2004, within their primary breeding range. I measured habitat variables at nest sites and random sites in the study area to characterize nest habitat selection, and investigated breeding incidence with a laboratory analysis of circulating concentrations of the plasma yolk precursors vitellogenin (VTG) and very-low density lipoprotein (VLDL). The low hen and nest survival rates I observed combined with the substantial proportion of non-breeders on the breeding ground (up to 28%) may be responsible for the observed declines in abundance if annual survival rates are not high enough to maintain stable populations. Scoters avoided nesting in graminoid habitat, but nested in all other scrub or forested plant communities in proportion to their availability, selecting sites with more cover, higher variability of cover, and closer to edge and water than random sites. At the nest habitat scale, scoters are generalists, which may reduce the foraging efficiency of nest predators.
    • Carbon flux and particle-associated microbial remineralization rates in the northern Bering and southern Chukchi seas

      O'Daly, Stephanie Hicks; McDonnell, Andrew M. P.; Hardy, Sarah M.; Johnson, Mark A. (2019-12)
      It has been hypothesized that climate change will reduce the strength and episodic nature of vernal phytoplankton blooms, increase heterotrophy of microbes and zooplankton, and weaken the tight coupling between pelagic and benthic production that is characteristic of Arctic continental shelves. As a part of the Arctic Shelf Growth, Advection, Respiration, and Deposition rates measurement (ASGARD) project, I quantified sinking particle fluxes and incubated sinking particles to measure the rate of microbial respiration associated with those particles. These measurements were used to characterize the strength of the pelagic-benthic connection. After a record-breaking year of warm temperatures and low-ice conditions in the northern Bering and southern Chukchi Seas, we observed massive vernal fluxes of sinking particulate organic carbon, ranking amongst the highest observed in the global oceans. Moreover, low rates of particle-associated microbial respiration indicate negligible recycling of sinking organic matter within the water column. These results suggest that the strength of the biological carbon pump may be maintained or enhanced in a warming Arctic, supporting strong benthic and upper trophic level productivity and carbon export.
    • Changing strategies in Seward Peninsula reindeer (Rangifer tarandus tarandus) management

      Oleson, Heather J. (2005-12)
      Reindeer (Rangifer tarandus tarandus) management techniques have changed since the founding of the reindeer industry on the Seward Peninsula in 1891. From 1891-1915, herds were small and management was intensive. Between 1915 and 1944, community herds and joint stock companies were formed. Herd management was extensive and herds were large and relatively free roaming. A period of re-privatization followed from 1944 to 1960, during which a limited number of moderately stocked ranges were established. The era after 1960 saw the introduction of several new forms of technology, some of which became catalysts for broad changes in reindeer management. Snow machines (c. 1960s), helicopters (c. 1970s), radio telemetry (c. 1980s), and Internet use became an integral part of how reindeer were managed. Most recently, satellite telemetry and online mapping have been developed as herd management tools. Combining telemetry, mapping programs, and the Internet allows herders to monitor range use, herd movement, and whether their animals need to be moved to refuge areas to prevent mixing with caribou. Equipped with this knowledge, herders can more effectively use ATV's and aircraft to manage their herds.
    • Characterizing the berthing load demand at Alaska Department of Transportation and Public Facilities Ferry Landings

      Hutchinson, Jonathan; Metzger, Andrew; Hulsey, Leroy; Dong, YongTao (2011-08)
      This report provides design guidelines and recommendations for side-berthing loads on ferry landing structures. Berthing loads on ferry berthing structures are not well understood due to a lack of information and research for ferry class vessels. The load criteria for the design of ferry berthing structures are thus often based on a number of assumptions, often leading to uneconomical or unreliable structures. The Alaska Department of Transportation (AKDOT&PF) recognizes the need for an improved information base on berthing loads from ferry class vessels, for the design and operation of future facilities within the Alaska Marine Highway System (AMHS). This study involves a one year empirical investigation into side-berthing loads at the Auke Bay ferry landing located in Juneau, Alaska. Measurements of fender displacement, approach velocity, and pile strain were used to determine berthing loads from scheduled berthings from four different vessels. Measured parameters were analyzed statistically, and used to establish distributions and design recommendations for berthing energy, force, velocity, and berthing coefficient based on reliability theory. This study provides an assessment of load criteria currently used by the AK DOT&PF Marine Department, as well as design load recommendations for both service and ultimate side-berthing loads from ferry class vessels.
    • Classification and signal processing of radio backscatter from meteors

      Klemm, Jared; Thorsen, Denise; Bossert, Katrina; Collins, Richard; Mayer, Charlie (2019-12)
      Ground-based radar systems are routinely used to detect the trails of ionized particles that are formed by meteoroids falling through Earth's atmosphere. The most common use for these meteor radar systems is for atmospheric wind studies of the mesosphere and lower thermosphere (80-100 km altitude). Because these meteor trails are embedded in the background winds of the middle atmosphere, atmospheric winds in that region can be measured by observing the radial velocities of the trails. There has also been a considerable amount of research over the last few decades into estimation of neutral atmospheric temperatures using the measured decay time of meteor trails. Several methods exist for estimating atmospheric temperature using meteor radar observations, but there are limitations to these approaches. This thesis focuses on examining aspects of meteor radar signal and data processing, specifically interferometry and echo classification. Interferometry using the measured signal phase differences between antennas allows for the location of meteor trails to be unambiguously determined. Classification schemes are used to identify which echoes can be modeled as underdense meteors, overdense meteors, or other potentially non-meteor echoes. Finally, based on the proposed classification scheme, this thesis examines several temperature estimation methods for both underdense and overdense echoes and discusses the current issues in this area. Preliminary results from a newly installed meteor radar at Poker Flat Research Range are also presented.
    • Climate and predictability of Alaska wildfires

      Bieniek, Peter A. (2007-12)
      Wildfires burn an average of 3,760km² each year in Alaska, but varies greatly from year to year. These fires, started by human and natural causes, can endanger life and property when they approach populated areas. The relationship between seasonal area burned and monthly and seasonal average mean sea level pressure, surface air temperature, total column precipitable water, 500hPa and 700hPa geopotential height, 700hPa specific humidity and 1000-500hPa layer thickness is examined. The assessment was done by examining the spring and summer seasonal composites associated with extreme high and low seasons. This showed the predominant anomalies from the climatology for seasons of both extremes. Point correlations were also made between seasonal area burned and the aforementioned climate variables for the entire Northern Hemisphere. Points of particularly high correlation with area burned were used in multiple regressions for both spring and summer, and for the preseason only to predict seasonal area burned. Results show correlations of about 0.78 for the preseason regression and 0.91 for the total period. The seasonal area burned in Alaska is intimately linked with the ongoing synoptic situation on monthly and seasonal scales before and during the fire season.
    • Comparison of snowshoe hare populations in interior Alaska

      Flora, Bjorn (2002-12)
      Snowshoe hares, Lepus americanus, are a 'keystone' prey species in northern boreal forests and experience population fluctuations of 8-11-years. Despite intense responses of both vegetation and predators to changes in hare densities, landscape-scale comparisons of hare populations in Alaska have been limited to qualitative descriptions. We conducted capture-recapture studies of snowshoe hares at 5 locales in the Tanana valley, from Tok in the east to Clear in the west from 1999 to 2002. Snowshoe hare densities were highest in 1999 (x=6.36 ha⁻¹, SE=0.63) and declined thereafter. We were unable to detect declines in apparent survival during declining densities in our study populations. Movement distances did not vary temporally and persistence of individuals through declining densities may be associated positively with body condition at the peak. The relationship of hare pellets and hare densities was weak and limits the utility of this methodology for estimating hare densities in Interior Alaska.
    • Coping with bear country

      Greci, Dana (2001-12)
      'Coping with Bear Country' is a work of creative non-fiction, a genre in which non-fiction writers use dramatic techniques usually employed by fiction writers and poets (such as narration, dialogue, and detailed description) to look at their subjects. 'Coping with Bear Country' draws on the styles of nature writing, personal essay, and memoir, combining descriptions of natural history and tales of adventure with a look towards emotional landscapes reflected within them. At its most physical level, 'Coping with Bear Country' looks at the 'bearish' qualities of the complex land called Alaska, and at how a person simultaneously might both struggle against and embrace them. At this level, the work's focus is the author's personal struggle to make a home in a challenging land. But at its deepest level, 'Coping with Bear Country' digs more deeply, asking universal questions, exploring how faith takes root when we face our limitation and fear.
    • Decompression induced crystallization of basaltic andesite magma: constraints on the eruption of Arenal volcano, Costa Rica

      Szramek, Lindsay Ann (2004-08)
      Continuously active since 1968, Arenal Volcano in Costa Rica has undergone various eruption styles. The deposited magmas, whereas geochemically similar, show a complex history of magma chamber processes, which are not fully understood. The intricate mixing histories of the phenocrysts and lack of oxide pairs have made determination of the volatile content and oxygen fugacity difficult by conventional methods. Phase equilibria experiments were carried out between 200-50 MPa and 940-1075°C in a TZM furnace at fO₂ of NNO and water saturation. Time in the furnace varied from 7 to 30 hours at constant pressure and temperature. Examination of the natural and experimental phase assemblages constrained the probable pre-eruptive conditions for Arenal magmas to be 50-80 MPa and 950-1040°C. For decompression experiments, the sample was initially held at two conditions 200MPa and 950°C and 60MPa and 1050°C. The samples were then decompressed by 5-30 MPa pressure steps held for 20 seconds to 8 hours until 20 MPa was reached, approximating average decompression rates of 0.25, 0.025, and 0.0013 MPa/s. Textures formed in the experiments and seen in the natural samples constrain the probable ascent rate of the Arenal magma to 0.05 mls. The ascent rate increases as explosivity increases.
    • Design and implementation of novel radar modulations for the SuperDARN radar at Kodiak Island, Alaska

      Balaji, Mrinal S. (2007-05)
      The Kodiak SuperDARN (Super Dual Auroral Radar Network), located on Kodiak Island, Alaska, is a coherent-backscatter radar sensitive to Bragg scatter from ionospheric irregularities. SuperDARN transmitters send out a sequence of seven pulses that aid in the formation of complex autocorrelation functions (ACFs). These ACFs allow for estimating the power, velocity and the spectral widths of the scattering plasma waves. However, the multipulse sequence used currently has some characteristics that are not ideal for the intended purpose. In addition, the analysis technique for estimating the properties of the ACF assumes that there is only a single velocity component present in each range cell at one time. In this study, the aperiodic radar technique designed by Dr. John D. Sahr and Dr. Sathyadev. V. Uppala was investigated to design an optimized transmission sequence that would have no repeated lags, a minimum number of inherently missing lags and no loss of lags due to Tx-on/Rx-off conflicts. With the designed transmission sequence, efficient analysis of data is possible through the use of a standard spectral estimator, the modified covariance technique. The design enhances the ability of the radar to discriminate targets in the same range bin.
    • Design and implementation of photodiode-based receiver systems for a 1574 nm eye-safe lidar

      Yue, Jia (2004-08)
      In this thesis we present the design, implementation and testing of a photodiode-based receiver systems for a 1574 nm eye-safe lidar. The specific goal of this thesis was to precisely and accurately convert and amplify nW optical signals into robust mV voltage signals. The receiver system incorporates both analog and digital circuitry and a software-based digital processing system. Four analog circuits were constructed and tested using both PIN diodes and APDs, and two high-speed commercial op amps. A single high-speed digital processing system was tested with each of the analog circuits. The analog circuitry was found to be the fundamental limitation on the performance of the system with the receiver bandwidth limited to -6 MHz for the PIN-based systems and -14 MHz for the APD-based systems. Inherent oscillations in the analog circuits were successfully removed using digital filtering techniques in the software-based digital processing systems. Furthermore, the APD-based systems had less rms noise than the PIN-based systems. The lidar receiver system could support measurements with a maximum resolution of 10 m and a range of up to 40 km.
    • Design of microcontroller based generic radar controller

      Kolatkar, Aditi (2004-05)
      Increasingly radar stations contain multiple radar systems, each individually controlled. Non-standard control requires that a user of multiple systems learn each system separately. Additionally, multiple radar controllers make coordination of multiple systems difficult. The goal of this thesis is to design a generic radar controller that can be used to operate any pulsed radar system or multiple radar systems simultaneously. The Generic Radar Controller attempts to meet and improve upon the specifications of a previous radar controller and collapse its rack-mounted system into a single PC card. The University of Alaska Generic Radar Controller (UAF-GRC) is a microcontroller based PC card with a minimum of 16 control channels. Each channel can be individually programmed to provide pulses of 400 ns duration up to several milliseconds and variable pulse repetition intervals with a timing resolution of 10 ns. The hardware and software issues that appeared during the design phase are discussed in the thesis. The thesis concludes with improvements of UAF-GRC over the previous radar controller.