• Obfuscation fingerprinting in Android binaries

      Van Veldhuizen, Matthew Philip (2015-04)
      There are many way to protect code from reverse engineering. One such way is to obfuscate either the source code, machine code or bytecode. Obfuscating Android applications not only makes it harder to reverse engineer, it can also speed up execution by reducing the size of the application and removing unnecessary code. One method of obfuscation is to do it manually and the other method is to use an obfuscation program. However, it may become necessary to reverse obfuscation, because of the loss of source code or when investigating malware, trojans, or other harmful applications. This process is called deobfuscation. Once an application has been obfuscated performing deobfuscation is a tedious task, and knowing how the application was obfuscated would increase the probability of correctly reversing the obfuscation. By examining four Android application obfuscators I successfully identified distinct fingerprints within each of the obfuscated binaries by building a simple Android application, obfuscating it, and then comparing obfuscated and unobfuscated bytecode. Using these fingerprints I was able to associate each obfuscator with an approximate probability that it was used to perform the obfuscation.
    • Oblique impact cratering: A comparison of low-velocity experiments to high-velocity experiments

      Hessen, Katie K.; Hessen, Robert; Dean, Ken; West, Michael; Chappelow, John; Christensen, Douglas (2008-12)
      Previous impact cratering experiments performed by Gault and Wedekind (1978), used high-velocity impactors (~1 km/s to 7 km/s) to quantify how impact angle affects crater morphology and ejecta pattern. Low velocity (144 m/s to 260 m/s) impact experiments were conducted in a vacuum chamber with a basaltic sand target material and impact angles ranging from 0.5° to 90° (vertical) at the Impact Cratering Laboratory at the University of Tokyo Kashiwa. The crater morphology and ejecta distribution from low velocity impacts are then compared to results from the higher velocity projectiles. When adjustments are made to the low-velocity measurements to account for differences in velocity, the displaced mass ratio follows a sinθ distribution, as is seen in the high- velocity experiments. In the low-velocity experiments, asymmetric ejecta is present at slightly higher impact angles. The presence of an uprange forbidden zone occurs at the same impact angle (20°) in both sets of experiments. The most striking difference between the two sets of experiments is the complete lack of a downrange forbidden zone in all of the low-velocity experiments. With the exception of the very lowest impact angles, these low-velocity oblique impact experiments yield similar changes in crater characteristics with varying impact angles to the previous high-velocity experiments.
    • Observable effects of attention, posture, ergonomics and movement in the classroom

      Healy, Joanne; Bult-Ito, Abel; Anahita, Sine; Charles, Walkie; Irish, Joel; Kaden, Ute (2014-05)
      Two studies related to student attention, posture, school ergonomics, student behavior (leaning, standing up, and moving), and learning engagement were conducted in Alaska. The Children's Postural Improvement Study (CPIS) looked at the observable effects of two interventions on attention. In the Classroom Environmental Study (CES) a baseline ergonomic survey compared observed student behavior and classroom arrangements. The purpose of the CPIS was to investigate the effects of a postural education program, consisting of five 30-minute instructional sessions, as compared to a nutritional intervention at two elementary schools and its effect on attention. Three quantitative tools measured attention, the post-Partial Vanderbilt ADHD Teacher and Parent rating scales and pre- and post-math fluency tests. Qualitative measures included pre- and postintervention photographs, daily comments from students after the lesson, and post open-ended-question student and teacher surveys. Based on the post-surveys, participants valued their good posture and made concentrated efforts to improve it. Quantitative results of this postural study revealed no correlation between posture and attention. The follow-up CES examined the current state of furniture in 78 classrooms and pedagogical practices in regard to student movement and learning engagement in eight fourth-grade classrooms in three elementary schools. Two-way ANOVA revealed a significant school effect for leaning and significant classroom nested within school effects for leaning, standing up, and moving. Classroom sketches were coded to examine movement and posture. No significant difference for desk clusters by grade, or by school using the Chi-squared test were found, but there was a significant difference comparing the seating relationship to instructional delivery by grade and by school. Recommendations for future research and changes within Schools of Education and school districts to improve posture and learning engagement include: adjust current students' chairs and desks to meet their ergonomic needs; raise awareness of and inform pre-service, current teachers, students, and parents about ergonomic health concepts; encourage teachers to move around the classroom while instructing to engage students as they track the teacher's movement; and limit instructional periods to 20 minutes or less to allow for student movement breaks.
    • Observation and analysis of whistler mode echoes received by RPI on IMAGE at high latitudes

      Chen, Xiangdong (2001-05)
      Whistler-mode wave-injection experiments with Radio Plasma Imager (RPI) on IMAGE offer an opportunity to observe the whistler-mode echoes. We have performed raytracing studies to investigate accessibility of whistler-mode waves injected from IMAGE to various regions of the magnetosphere and also to other satellites such as Akebono. RPI detected both discrete and diffuse whistler-mode echoes during our observing period (April 21 to August 28, 2000) when IMAGE was at a low altitude (1̃000-7000 km) and mid-to-high latitudes (>25 - 40S̊) near its perigee. We believe that the discrete echoes are the result of RPI signals reflected at the Earth-ionosphere boundary and the diffuse echoes are the result of scattering of RPI signals by meter-scale irregularities. Raytracing analysis shows that both ducted and nonducted ray propagation are needed to explain the observed whistler-mode dispersion. Comparison of electron densities obtained from our raytracing analysis of dispersion with the electron densities obtained by Kletzing et al. in the Auroral Zone shows that these density values deduced from RPI data were about ten times higher. This may be because the antenna radiation efficiency is higher at higher electron densities.
    • Observation and analysis on the characteristics of strain induced by frost heave for a full-scale buried, chilled gas pipeline

      Yang, Kun; Huang, Scott; Chen, Gang; Darrow, Margaret (2013-12)
      This thesis examines the strain characteristics of a large-scale, buried chilled gas pipeline in the discontinuous permafrost region. A full-scale chilled pipeline gas experiment was conducted in Fairbanks, Alaska. The test pipeline had a length of 105 m and a diameter of 0.9 m. One-third of the pipeline was located in permafrost and the rest was in non-permafrost. The monitoring data were collected from December 1999 to January 2005 including both freezing and thawing phases. In the transition zone between frozen and unfrozen soil, the foundation experienced a vertical movement caused by differential frost heave. The test results indicated that the bending action was the main factor for the pipeline for the circumferential and longitudinal strain distribution of the pipeline. Moreover, linear relationships were developed between frost heave and the longitudinal strain at the top and the bottom (i.e., 0� and 180�) of the pipe. The developed equations can be used to predict the strain of the pipe caused by differential frost heave for future tests with similar site conditions.
    • Observations and generation mechanisms of slow-mode waves in the magnetosheath

      Yan, Ming; Lee, Lou; Craven, John; Hawkins, Joseph; Sentman, Dave; Watkins, Brenton (1995)
      The interaction of solar wind with the geomagnetic field leads to the formation of the bow shock, magnetosheath, and magnetopause. Magnetohydrodynamic (MHD) slow-mode structures with a plasma density enhancement and magnetic field depression have been observed to appear frequently in the inner magnetosheath. In addition, the slow-mode structures usually consist of slow-mode waves with a smaller length scale. These slow-mode structures and waves are studied in this thesis through satellite observations and numerical simulations. We find, through satellite observations, that some of the slow-mode structures are associated with Alfven waves in the solar wind. On the other hand, simulations show that slow-mode waves are generated through the interactions between the bow shock and interplanetary shocks, magnetosonic waves, rotational discontinuities, or Alfven waves. The generated slow-mode waves stay in the inner magnetosheath for a long time (about 15 minutes) before the wave energy is convected away tailward. Of particular importance are the interactions between the bow shock and interplanetary rotational discontinuities or Alfven waves. These interactions generate a region with an enhanced plasma density and depressed magnetic field, which is very similar to the slow-mode structures observed in the inner magnetosheath. Based on observations and simulations, it is suggested that the interactions of various types of solar wind fluctuations with the bow shock may lead to the frequent appearance of slow-mode structures and waves in the inner magnetosheath. The generated slow-mode structures have strong pressure variations, and may impinge on the magnetopause as strong pressure pulses.
    • Observations Of Metal Concentrations In E-Region Sporadic Thin Layers Using Incoherent-Scatter Radar

      Suzuki, Nobuhiro; Watkins, Brenton (2006)
      This thesis has used incoherent-scatter radar data from the facility at Sondrestrom, Greenland to determine the ion mass values inside thin sporadic-E layers in the lower ionosphere. Metallic positively-charged ions of meteoric origin are deposited in the earth's upper atmosphere over a height range of about 85-120 km. Electric fields and neutral-gas (eg N2, O, O2) winds at high latitudes may produce convergent ion dynamics that results in the re-distribution of the background altitude distribution of the ions to form thin (1-3 km) high-density layers that are detectable with radar. A large database of experimental radar observations has been processed to determine ion mass values inside these thin ion layers. The range resolution of the radar was 600 meters that permitted mass determinations at several altitude steps within the layers. Near the lower edge of the layers the ion mass values were in the range 20-25 amu while at the top portion of the layers the mass values were generally in the range 30-40 amu. The numerical values are consistent with in-situ mass spectrometer data obtained by other researchers that suggest these layers are mainly composed of a mixture or Mg +, Si+, and Fe + ions. The small tendency for heavier ions to reside at the top portion of the layers is consistent with theory. The results have also found new evidence for the existence of complex-shaped multiple layers; the examples studied suggest similar ion mass values in different layers that in some cases are separated in altitude by several km.
    • Obstacle detection with Kinect V2 on a ground robot

      Fisher, Laurin; Lawlor, Orion; Hartman, Chris; Genetti, Jon (2018-12)
      This paper is about determining whether using a Kinect V2 (Xbox One Kinect) mounted on a LAYLA ground robot can be used to detect obstacles, by generating a heightmap with the depth data. We take several factors into consideration including: framerate, power consumption, field of view, and data noise.
    • The occurrence and characteristics of plastic pollution in Alaska's marine birds

      Day, Robert H. (1980-05)
      Major aspects of the occurrence and variation of plastic particles in the stomachs of marine birds in Alaska were examined. A total of 448 of 1 ,968 individuals and 15 of 37 species of marine birds contained plastic. Species feeding primarily by pursuit-diving and surface-seizing had the highest incidence of plastic. Crustaceanand cephalopod-feeders had a higher incidence of plastic than did fish-feeders. Birds from the Aleutian Islands averaged more particles than did birds elsewhere in Alaska. No sexual differences in plastic ingestion were found, but subadults averaged more plastic than did adults. There was a general increase in plastic ingestion between 1969 and 1977. An annual cycle of plastic ingestion was recorded, with the greatest ingestion in mid-summer. No overt effects of plastic on the physical well-being of the birds were found, but non-breeding in the Parakeet Auklet may have been caused by high plastic ingestion.
    • Occurrence patterns of whistler mode (WM) echoes observed by RPI/IMAGE and their relation to geomagnetic activity

      Reddy, Amani (2007-12)
      This thesis presents an analysis of whistler mode (WM) echoes observed at altitudes less than 5,000 km by the Radio Plasma Imager (RPI) on the IMAGE satellite. WM echoes are generated either by specular reflection (SR) of RPI signals at the Earth-ionosphere boundary (~90 km) or by magnetospheric reflection of RPI signals [...] at altitudes greater than 1,000 km [Sonwalkar et al., 2004; Sonwalkar et al., 2006]. These echoes are further influenced by field aligned irregularities (FAI) and are categorized into discrete, multipath or diffuse SR- and MR- WM echoes, based on their characteristic spectral forms. A survey of WM echoes observed during January 2004- December 2005 showed that WM echoes occurred at all latitudes and under moderate geomagnetic conditions. Occurrence patterns of WM echoes observed in August-December 2005 during geomagnetically quiet and disturbed periods indicate that geomagnetic storms lead to significant changes in FAI that affect the propagation of WM echoes. Our results help (1) in better understanding propagation and generation mechanisms of naturally occurring WM waves, and (2) in planning future WM wave injection experiments in space.
    • Ocean Wilderness In Theory And Practice

      Barr, Bradley W.; Kruse, Gordon; Kliskey, Andrew; Alessa, Lilian; Koester, David (2012)
      Wilderness preservation has been an important focus of resource conservation since the dwindling number of wild places was perceived by some as losing a valued part of our collective natural and cultural heritage. While wilderness preservation efforts have been almost entirely focused on the land, recently there has been growing interest in "ocean wilderness." However, implementation has been constrained by the lack of a common vision of how "wilderness" is applied to the ocean, and how such areas should be managed and preserved. The purpose of this work was to identify and evaluate potential definitions of ocean wilderness and the values and qualities such areas possess, and to determine how they might be effectively identified and managed to preserve their wilderness character. This research focused on articulating a robust definition for "wilderness waters," within the context of how wilderness is currently conceived and articulated in law and policy, as well as evaluating how such areas might be most appropriately identified and managed. Extensive inventories were conducted of existing ocean wilderness areas, focused on North America, to determine what currently exists, how these areas are managed, and how future ocean wilderness designations should be prioritized. A survey was conducted, targeting resource managers and scientists, to identify preferences and perceptions of ocean wilderness and its potential stewardship. The survey results suggested that coastal waters possessed considerable values and qualities of wilderness, particularly areas adjacent to existing designated wilderness, that certain human uses might be appropriately permitted, and that there was much support for expanding the area of coastal waters designated as wilderness. The research also suggested that the North American Arctic might offer many opportunities for preserving ocean wilderness, in close collaboration with the Indigenous communities in this region. A number of recommendations were offered including that priority should be given to evaluating and designating areas adjacent to designated coastal wilderness areas, that the existing legal and policy framework in North America can be effectively used to expand the "wilderness waters" system, and that more work needs to be done to build the constituencies of support essential to accomplish this task.
    • Oceanic emissions of sulfur: Application of new techniques

      Jodwalis, Clara Mary; Benner, Richard L. (1998)
      Sulfur gases and aerosols are important in the atmosphere because they play major roles in acid rain, arctic haze, air pollution, and climate. Globally, man-made and natural sulfur emissions are comparable in magnitude. The major natural source is dimethyl sulfide (DMS) from the oceans, where it originates from the degradation of dimethysulfonioproprionate (DMSP), a compound produced by marine phytoplankton. Global budgets of natural sulfur emissions are uncertain because of (1) the uncertainty in the traditional method used to estimate DMS sea-to-air flux, and (2) the spatial and temporal variability of DMS sea-to-air flux. We have worked to lessen the uncertainty on both fronts. The commonly used method for estimating DMS sea-to-air flux is certain to a factor of two, at best. We used a novel instrumental technique to measure, for the first time, sulfur gas concentration fluctuations in the marine boundary layer. The measured concentration fluctuations were then used with two established micrometeorological techniques to estimate sea-to-air flux of sulfur. Both methods appear to be more accurate than the commonly used one. The analytical instrument we used in our studies shows potential as a direct flux measurement device. High primary productivity in high-latitude oceans suggests a potentially large DMS source from northern oceans. To begin to investigate this hypothesis, we have measured DMS in the air over northern oceans around Alaska. For integrating and extrapolating field measurements over larger areas and longer time periods, we have developed a model of DMS ocean mixing, biological production, and sea-to-air flux of DMS. The model's main utility is in gaining intuition on which parameters are most important to DMS sea-to-air flux. This information, along with a direct flux measurement capability, are crucial steps toward the long-term goal of remotely sensing DMS flux. A remote sensing approach will mitigate the problems of spatial and temporal variability. The new developments in methodology, field sampling, and modeling put forth in this thesis are tools we have used to better understand and quantify sulfur gas emissions from northern oceans, which appear to be a significant source of sulfur to the global atmosphere.
    • Odors And Ornaments In Crested Auklets (Aethia Cristatella): Signals Of Mate Quality?

      Douglas, Hector D., Iii; Springer, Alan M. (2006)
      Crested auklets (Aethia cristatella) are small colonial seabirds that display an ornamental feather crest and emit a citrus-like odorant during the breeding season. In this study odors and ornaments were investigated as possible signals of mate quality. Crest size was negatively correlated with the stress hormone corticosterone in males, but this was not the case in females. Body condition was negatively correlated with corticosterone in females, but this was not the case in males. Corticosterone levels were interpreted as an index of physiological condition, and it was concluded that males with longer crests were more competent at meeting the social and energetic costs of reproduction. I hypothesized that the crested auklet odorant: (1) functions as a chemical defense against ectoparasites, (2) is assessed as a basis for mate selection, (3) is facilitated by steroid sex hormones. Laboratory and field experiments showed that synthetic replicas of the crested auklet odorant repelled, impaired, and killed ectoparasites in a dose-dependent fashion. Chemical concentrations in plumage were at least sufficient to repel and impair ectoparasites. Chemical emissions from breeding adult crested auklets peaked at the time of egg hatching when young are most vulnerable to tick parasitism. In males, chemical emissions were correlated with crest size, a basis for mate selection. Presentation of synthetic aldehydes elicited behaviors similar to those that occur during courtship. Captive crested auklets responded preferentially to synthetic replicas of their odor, and the highest frequency of response occurred during early courtship. These results show that the chemical odor could be a basis for mutual mate selection. Production of the chemical odorant may be facilitated by steroid sex hormones since octanal emission rates were correlated with progesterone in males. Finally it was determined that the chemical composition of odorants in crested auklets and whiskered auklets (A. pygmaea) differed in three key respects. This suggests that an evolutionary divergence occurred in the odorants of the two species similar to what has been suggested for ornamental traits. In conclusion, crested auklets appear to communicate with odors and ornaments, and these signals may convey multiple messages regarding condition, quality, and resistance to parasites.
    • Oil and wildfire effects on nutrient cycling and microbial diversity in subarctic mineral soils

      Garron, Jessica I.; Braddock, Joan; Valentine, David; Lindstrom, Jon (2007-05)
      In 1976 crude oil was experimentally spilled on a plot near Fairbanks, Alaska to mimic an oil pipeline spill. The plot and surrounding area were further disturbed by wildfire in 2004. Although the fire burned organic matter on the plot surface, substantial subsurface oil remained. After the fire, soil samples from oiled/burned, burned, and control plots were collected to evaluate the effects of disturbance on nutrient cycling and soil bacterial communities. Samples were analyzed for total nitrogen (N), soil carbon (C) and N mineralization, N fixation, total bacterial diversity (16S rDNA), and functional genetic diversity (nifH). Inorganic N was low in all soil types. In control and burned soils there was net N mineralization, but in oiled/burned soils there was significant N immobilization. Carbon mineralization was much higher in oiled/burned soils than control or burned soils. While the highest N fixation potential was measured in oiled/burned soils, the diversity of the N-fixing bacterial community in those soils was about the same as that of the control. For 16S rDNA, diversity was higher in control and burned soils than in oiled/burned soils. Overall, the type of disturbance and the length of time since disturbance both affected microbial function and diversity
    • On interannual variability and climate change in the north Pacific

      Salmon, David Kurt (1992-05)
      Long term changes in the atmospheric and oceanic environment of the North Pacific were investigated for the period 1946-1991. A climatology of North Pacific wind stress curl was developed because of the relevance of changes in wind stress curl to both oceanic and atmospheric variability. The dominant scales of spatial and temporal wind stress curl variability were determined and examined within the context of observed changes in North Pacific air temperature, sea surface temperature (SST), sea ice cover, oceanic mass transport and the occurrence of blocking anticyclones. Relationships between these variables and indices of tropical Pacific variability were also determined on interannual time scales. During 1976-1988, phase relationships were very strong between long term mean anomalies of wind stress curl, SST, air temperature, sea ice cover, The Pacific North American index, the Southern Oscillation Index (SOI), and tropical Pacific SST. Long term mean anomalies of these parameters did not change sign during 1976-88. These strong phase relationships did not occur amongst these variables during any other period of the record. The 1976-1988 period is characterized by intensified storminess, the decreased occurrence of blocking anticyclones, and decreased sea ice cover in the subarctic North Pacific. Intensified atmospheric circulation also occurred in the western Pacific subtropical anticyclone. Anomalously low SST occurred across the central and western North Pacific during this period while anomalously high SST was present in the eastern North Pacific adjacent to North America. Changes in the sign of the long term mean anomalies of wind stress curl, central North Pacific SST and the SOI suggest that this climate regime ended or relaxed after 1988. After 1975, long term changes in anomalies of the Southern Oscillation Index, tropical Atlantic wind stress, Sahel rainfall, and Greenland Sea ice cover have characteristics similar to those observed in the North Pacific. It is suggested that the climate anomalies observed in the North Pacific during 1976-1988 occurred as part of a hemispheric or global scale climate regime.
    • On the biology of eelgrass in Alaska

      McRoy, C. Peter (1970-05)
      A collection of essays is presented that are a contribution toward a biology of eelgrass (Zostera marina L.) in Alaska. Eelgrass is the most abundant seagrass on the coast of Alaska. The distribution of the plant in Alaska is disjunct and extends from Kotzebue Sound to the southern border of the state. The present circumboreal distribution is thought to be the result of dispersal from a west Pacific origin around the Pacific rim and through the Arctic into the Atlantic. Ten widely scattered eelgrass populations in Alaska have been sampled for quantitative comparison. The highest standing stocks (1510 g dry wt/m²) were found in Kinzarof and Izembek lagoons on the Alaska Peninsula. The caloric content, chlorophyll a concentration, turion density, and leaf size varied greatly among the populations. The eelgrass in Safety Lagoon survives the arctic winter under one meter of sea ice in conditions of extremely low light intensity and anoxic water. In chemical composition, eelgrass is similar to other angiosperms, but it also reflects adaptation to the marine environment. Trace elements are accumulated in the plant in proportion to their concentration in the sea. The roots as well as the leaves function as the sites for the uptake of phosphate. Using radioactive phosphate it was shown that phosphate was absorbed greatest in the light and transported throughout the plant; a portion of the phosphate removed from solution by the roots was lost across the leaves. The metabolism of eelgrass in the dark is extremely dependent on temperature. Physiological differences exist between shallow water and deep water plants and between summer and winter plants. A depressed rate of respiration in winter is an adaptation enhancing survival in high latitudes.
    • On the detection of virtual machine introspection from inside a guest virtual machine

      Marken, Brandon Ashlee; Lawlor, Orion; Price, Channon; Barry, Ronald; Hartman, Christopher; Genetti, Jon (2015-12)
      With the increased prevalence of virtualization in the modern computing environment, the security of that technology becomes of paramount importance. Virtual Machine Introspection (VMI) is one of the technologies that has emerged to provide security for virtual environments by examining and then interpreting the state of an active Virtual Machine (VM). VMI has seen use in systems administration, digital forensics, intrusion detection, and honeypots. As with any technology, VMI has both productive uses as well as harmful uses. The research presented in this dissertation aims to enable a guest VM to determine if it is under examination by an external VMI agent. To determine if a VM is under examination a series of statistical analyses are performed on timing data generated by the guest itself.
    • On the dynamics of the Alaska coastal current

      Luick, John Leonard; Royer, Thomas C. (1988)
      The Alaska Coastal Current (ACC) in the northern Gulf of Alaska is a wind- and buoyancy-driven near-surface jet primarily maintained by the horizontal salinity gradient due to fresh water entering at the coast. It serves as the major source of fresh water to the North Pacific Ocean. The buoyancy driving force is the major focus of this investigation. The study area is situated just "downstream" of Prince William Sound (PWS), a large estuary whose surface outflow is seen to occupy a narrow inshore band after joining the ACC. The effect of this band appears to be the formation of an occasional double maximum in the ACC. The period focused on in this study was selected on the basis of weak windstress but large fresh water input in order to emphasize the buoyancy forcing. The TS characteristics and a water mass tracing technique are used to separate the thermal and haline signals in the buoyancy forcing and to track the origin and fate of the source waters of the study area. The buoyancy driving force is shown to be primarily haline, with temperature playing a secondary, moderating role. Because of the large topographic variability and sloping density interfaces, and in order to exploit the available data, a diagnostic model retaining the baroclinicity and bottom topography terms was chosen to study the dynamics. Model premises are verified by results from hydrographic surveys, moored current meters, and a profiling current meter. The model predicts a midshelf region of negligible sealevel gradient, with a nearshore ($\approx$70 km wide) band over which the sealevel changes by about 25 cm. The sloping surface drives a strong ($\approx$100 cm/s) surface flow, which decreases to zero and reverses below about 100 m due to the opposing baroclinic pressure gradient. The flow splits around a shoal region. The onshore portion joins the outflow from PWS and accelerates downstream forming a double maximum. The offshore segment forms a large meander before rejoining the rest of the ACC, advecting midshelf water shoreward. The momentum balance is dominated by the JEBAT terms, which primarily determine the flow along and across contours of f/H.