• Scintillation at K-band and Ka-band frequencies

      Kim, Táe-hong (2000-05)
      The need for higher bandwidth and smaller antenna size for satellite communications led NASA to fund the Advanced Communications Technology Satellite (ACTS) and propagation research for K-band and Ka-band frequencies. From December 1993 to December 1998, seven sites in North America have collected and processed power measurements at 20.2 and 27.5 gigahertz from ACTS, a geostationary statellite located at 100 ̊West longitude. The thesis compares scintillation measurements to eight scintillation prediction models, proposes a cumulative distribution model to help predict the percentage of time scintillation exceeds a given threshold, examines the effects of frequency on scintillation magnitudes, and proposes a climate model based on moisture content to help predict scintillation magnitudes. The study concludes that the scintillation prediction models are dependent on the climate, the frequency dependence is a function of climate, and the moisture content in the atmosphere dictates the percentage of time large scintillation occurs.
    • Seasonal Effects Of Frozen Soil On The Stiffness Of Bridge Piles

      Horazdovsky, Jacob E.; Hulsey, J. Leroy (2010)
      In the northern regions, the upper layer of soil is frozen throughout winter months. Soil stiffness can be expected to increase several orders of magnitude as it changes from thawed to frozen. Thus, pile foundation systems embedded in frozen soils are considerably stiffer during winter months when subjected to lateral loads. This thesis explores and quantifies stiffness change for 16 inch diameter steel jacketed, reinforced concrete pilings in seasonally frozen silt. Two test piles were driven 20 feet into silty soil at a site approximately 1.5 miles from Fairbanks, Alaska. Three quasi-static lateral load cyclic tests were conducted on the piles throughout the year; one in September when the soil was thawed, the other two in January and March with frost depths of 4.5 and 7.5 feet respectively. Soil temperatures ranged from thawed to -18 degrees C. The shear demand on the piles increased by over 400 percent. Depth to fixity changed from approximately 6 pile diameters (thawed) to less then 0.75 pile diameters (frozen).
    • Seasonally Frozen Soil Effects on the Seismic Performance of Highway Bridges

      Hulsey, J. Leroy; Horzdovsky, Jacob E.; Davis, Duane; Yang, Zhaohui Joey; Li, Qiang (Alaska University Transportation Center, Alaska Department of Transportation and Public Facilities, 2011)
    • Second annual conference on Alaskan placer mining, focus on gold

      Campbell, B.W.; Finch, Louella (University of Alaska Mineral Industry Research Laboratory, 1980)
    • Sediment Relations of Selected Alaskan Glacier-fed Streams: Completion Report

      Guymon, G. L. (University of Alaska, Institute of Water Resources, 1974-06)
    • Seismic Design of Deep Bridge Pier Foundations in Seasonally Frozen Ground

      Shelman, Aaron; Levings, Jared; Sritharan, Sri (Alaska University Transportation Center, Alaska Department of Transportation and Public Facilities, 2010)
    • Seismic Performance and Design of Bridge Foundations in Liquefiable Ground with a Frozen Crust

      Yang, Zhaohui “Joey”; Zhang, Xiaoyu (Alaska University Transportation Center, Alaska Department of Transportation and Public Facilities, 2012)
    • Seismic performance of Alaskan structures

      Cherlopalle, Dileep; Hulsey, J. Leroy; Carlson, Robert; Shur, Yuri (2004-08)
      Alaska is the most earthquake prone area in the United States. On October 23, 2002 a 6.7 magnitude earthquake occurred in interior Alaska. This was followed by a magnitude 7.9 earthquake that occurred near Denali on November 3, 2002. The Denali earthquake was the largest inland earthquake in North America in almost 150 years. Only minimal structural damage was reported. Subsequently, structural engineers should question why minimal damage. As a part of an investigation to evaluate this unusual phenomenon, two structures were selected for seismic analysis, a building and a bridge. The building is at Alyeska Pump Station # 10 (3 miles from the epicenter) and only non-structural damage occurred. A 3 span truss bridge near Tok, Alaska was selected as the second. This structure experienced only minimal damage. Seismic analysis was performed on these two structures for horizontal excitations. A corrected seismic data from Pump Station # 10 was used as the earthquake excitation record. The maximums for displacements, member forces and member stresses were studied. The results show that no structural damage should have occurred for the building and minimal damage for the bridge. These findings compare favorably with field inspection results reported by others.
    • Seismic Performance of Reinforced Concrete Filled Steel Tubes in Soil

      Aguirre-Realpe, Diego A.; Kowalsky, Mervyn J.; Nau, James M.; Gabr, Mohammed (Alaska University Transportation Center, 2016-12)
      Reinforced concrete filled steel tube pile-columns are structural elements commonly used in bridge supports in high seismic regions because RCFSTs provide increased levels of strength, ductility, and energy dissipation as compared with traditional systems such as reinforced concrete (RC) or steel substructures. This study includes experimental and analytical studies that considered three main parameters: the diameter-to-thickness (D/t) ratio, the above-ground length (La), and the soil stiffness.
    • Seismic Performance of Steel Pipe Pile to Cap Beam Moment Resisting Connections

      Fulmer, Steven J.; Kowalsky, Mervyn J.; Nau, James M. (Alaska University Transportation Center, Alaska Department of Transportation and Public Facilities, 2013)
    • Selection of Preservatives for Marine Structural Timbers in Herring Spawning Areas

      Perkins, Robert A. (Alaska University Transportation Center, Alaska Department of Transportation and Public Facilities, 2012)
    • A sensitivity analysis of a biological module discovery pipeline

      Long, James; Roth, Mitchell; Rhodes, John; Marr, Thomas; Hartman, Chris (2015-05)
      Gene expression is the term applied to the combination of transcription, the process of copying information stored in DNA (deoxyribonucleic acid) into a transcript, and translation, the process of reading a transcript in order to manufacture a cellular product. Cellular products are typically proteins, which can combine either structurally or in concert to accomplish one or more tasks. Cooperating protein combinations are called modules, and it is thought that groups of transcripts with high correlation between their respective concentrations may indicate such modules. An open-source version of the CODENSE algorithm was developed with improved correlation methods to computationally test this hypothesis on an artificial transcription network containing a known module motif. The artificial network was used as input to a biochemical simulator in order to obtain synthetic transcription data, which was then fed to the pipeline whose purpose it is to discover modules in such data. Any discovered modules are compared to the known modules in the original network during a sensitivity analysis, where the process is repeated thousands of times with slightly varied parameters for each run. This process quantifies the sensitivity of pipeline output to each parameter of the pipeline, the most sensitive of which suggest what parts of the pipeline may be candidates for further refinement. The sensitivity analysis was then extended to include variation of biological network parameters, and noisy data. Lessons learned were then extended to the case of two known modules.
    • Separation of oil from oil water emulsion by the use of alginate gel encapsulated iron oxide and graphene oxide nanoparticles

      Ket, Nikhil; Aggarwal, Srijan; Patil, Shirish; Zhang, Lei (2017-05)
      Crude oil is used extensively around the world as a source of energy and as a means of producing various petroleum products. However, apart from being an excellent energy source, crude oil can also be a major pollutant in the form of oil spills. Crude oil spills can occur on land and in the ocean during the drilling, production, transportation or storage stages. While it is possible to reduce the damage caused to the environment by an oil spill, it is almost impossible to completely remove the adverse effects. New techniques need to be developed to clean-up oil spills at higher rates and with increased efficiency. The use of nanoparticles (NPs) for oil spill clean-up has gained popularity in recent years. This research focuses on the use of alginate gel as an immobilizing agent for nanoparticles that are then used for the removal of heating oil from an oil-water mixture. Iron Oxide and Graphene Oxide Nanoparticles were immobilized using sodium alginate in calcium chloride. The concentration of the nanoparticles was varied from 1 g/L to 5 g/L. The immobilized nanoparticles were then added to an oil-water mixture which was prepared by spiking heating oil in methanol and adding the solution to deionized water to achieve uniform distribution. 10 mL samples containing residual oil were extracted from the heating oil and water mixture at regular intervals and were analyzed for the residual oil. Measurements were carried out for residual hydrocarbons using Gas Chromatography/Mass Spectroscopy (GC/MS), Fluorescence Spectroscopy and Ultraviolet--visible spectroscopy (UV-Vis). Results from GC/MS show the highest percentage of oil being removed from the mixture by 2 g/L iron oxide (77%) and 2 g/L graphene oxide (81%) NPs. Analysis for residual hydrocarbons based on the time of contact showed promising results, with 75% of oil removed in 70 minutes. Further, based on the data obtained it was observed that the nanoparticles reached saturation after 70 minutes and were unable to remove additional quantities of oil from the mixture. Changing the nanoparticles from Iron Oxide to Graphene Oxide increased the amount of oil removed by 4%. This research will assist future development of oil spill clean-up and water treatment techniques that make use of nanoparticles as sorbents.
    • Serving Future Transportation Needs: Succession Planning for a State Department of Transportation Organization, Its People & Mission

      Perkins, Robert A. (Alaska University Transportation Center, Alaska Department of Transportation and Public Facilities, 2011)
    • Significant parameters of mining properties in arctic and subarctic areas of North America

      Hackney, D.A.; Lambert, C. (University of Alaska Mineral Industry Research Laboratory, 1983)
      This paper is a review of those factors unique to mining in the Arctic and subarctic. The information was developed from an exhaustive Literature search and personal visits to several northern mines in North America. The intent is to present a broad overview of many of these factors, to identify and stimulate consideration of parameters that are likely to be overlooked by companies end persons wlthout p rior arctic experience. Topics of discussion include exploration, cold weather plant design, blasting in permafrost, living conditions and employees relations. The appendices are a brief discussion of a number of the arctic and subarctic operations in North America. In brief, minlng in northern regions is practical provided the deposit has sufficient value to support the higher construction, transportation and operating costs associated with the remoteness and cold weather. Hiring and retaining good employees and integrating the native labor force into the operation have proven to be the most difficult problems. Equipment and plant operation are problems more easily solved.
    • SIMD within a register on linear feedback shift registers

      Ott, Karl (2015-04)
      Linear feedback shift registers (LFSRs) are used throughout a subset of cryptography. They have long been deployed as a means to generate a pseudo-random number stream. The random number generation provided by the LFSRs has been utilized in stream ciphers ranging from consumer to military grade. For example GSM privacy relies on the A5/1 stream cipher which in turn relies on LFSRs to generate the keystream. They are deployed because they are easy to construct, yet still provide strong cryptographic properties. The scope of this project is to speed up the simulation of LFSRs. The method of speeding up LFSRs is to use parallel operations to operate on multiple LFSRs at once. This is accomplished by using a method of SIMD. The method is SIMD within a register (SWAR). SWAR uses general purpose machine registers (eg. rax on an x86_64 machine). This means that 64 LFSRs can be simulated at once with one machine register using SWAR. This has the trade-off of latency vs throughput.
    • Simulation and analysis of wellbore stability in permafrost formation with FLAC

      Wang, Kai; Patil, Shirish; Chen, Gang (2015-07)
      Permafrost underlies approximately 80% of Alaska. Permafrost's high sensitivity to temperature variations plays a significant role in the stability of wellbores drilled through permafrost formations. Wellbore instability may cause stuck pipes, lost circulation, and/or collapse of the wellbore, resulting in extra cost and time loss. In order to minimize the influence of the heat produced during drilling, a vertical well is the only choice to penetrate permafrost formation. Fast Lagrangian Analysis of Continua (FLAC) was used in this simulation to test the minimum wellbore pressure to maintain stability in a permafrost formation. Three layers were set in the simulation model: clay, silt, and sand. With the drilling fluid temperature set at 343K and a 267K initial formation temperature, four different thermal times, i.e. 1 week, 1 month, 1 year, and 5 years, were tested to determine the minimum stable pressure. Pore pressure of the formation has the strongest effect on this pressure. And in a short operation period, drilling fluid temperature will not influence the minimum mud pressure value significantly. A regression analysis was conducted on the simulation results, and the minimum wellbore stable pressure was found to be a function of pore pressure, cohesion, frictional angle, temperature difference, conductivity difference, thermal time, and wellbore radius. With the help of this function, engineers could calculate stable pressure for wells in arctic area before drilling based on drilling fluid temperature.
    • Simulation based dimensionless waterflood performance curves for predicting recovery

      Dunn, Michael David (2000-08)
      Predicting waterflood recovery with simulation based dimensionless performance curves has advantages over the more traditional approaches in certain applications. This work discusses the advantages of the type curve approach in moderately mature fields where high resolution history matches are required. The method also has advantages when uncertainty analyses is important. The dimensionless type curve methodology can be applied to many different fields. A case study of a large, complex field is presented to show how the curves are created and how they can be applied. In this field, a study of the geology and stratigraphy indicated that reservoir continuity, permeability variance, and effects of faulting were the most important drivers of recovery efficiency. Simulations were performed on 45 datasets to describe waterflood performance over the range of variation. A spreadsheet program was created to predict recovery of any description, based on interpolations of the simulation results. The dimensionless curves can be used to predict full-field performance, as the basis of an integrated evaluation tool and/or for comparing actual performance to predicted performance. Using correlations to predict recoveries allows for ease of sensitivity analyses, and ease of application by casual users in an organization.
    • Simulation study on injection of CO₂-microemulsion for methane recovery from gas hydrate reservoirs

      Phale, Hemant A. (2006-08)
      Gas-hydrates are crystalline substances in which a solid water lattice accommodates gas molecules, such as methane, in a cage-like structure. A simulation study was conducted, both on 1-D and 2-D reservoir models, using STOMP-HYD simulator to evaluate a set of optimum parameters for methane recovery with simultaneous CO₂ sequestration. A simple 1-D analysis supports the hypothesis of enhanced gas-hydrate recovery using a CO₂-microemulsion injection technique. A series of simulations carried out on the 2-D reservoir model, revealed that the temperature and concentration of CO₂-microemulsion as well as initial CH₄-hydrate saturation in the reservoir are the key parameters in the replacement of CH₄ with CO₂ in the hydrate phase. The results from the 2-D analysis indicated that the moderate microemulsion with a CO₂ concentration in the range of 40% to 50% show good methane recoveries for the reservoir under consideration. Preliminary energy requirement calculations were also carried out to demonstrate the advantages of using the CO₂-microemulsion injection over the thermal stimulation method. These calculations indicated that the energy requirement for CO₂-microemulsion injection is less than 1/10th of that required in case of thermal stimulation method. The results support the hypothesis of using CO₂ microemulsion injection technique for methane recovery from gas-hydrate reservoirs.
    • Single lane live load distribution factor for decked precast / prestressed concrete girder bridges

      Millam, Jason Langdon (2004-08)
      The Alaska Department of Transportation (AKDOT) uses the decked precast, prestressed concrete bulb-tee girder for most of its bridge construction. The live load distribution factor (DF) equations provided by the American Association of State Highway and Transportation Officials (AASHTO) for the decked bulb-tee girder system do not differentiate between a single or multilane loaded condition. This practice results in a single lane load rating penalty for decked bulb-tee girder bridges. The research objective of this thesis is to determine DF simplified equations that accurately predict the distribution factor of the decked bulb-tee girder system when it is only subjected to single lane loading. Eight decked bulb-tee bridges were instrumented. Each bridge was loaded with a single load vehicle to simulate the single lane loaded condition. The experimental data were used to calibrate grillage models of the decked bulb-tee girder system. The calibrated grillage models were used to conduct a parametric study of the bulb-tee girder system subjected to single lane loaded condition. Eight new simplified equations that describe the single lane loaded distribution factor for both shear and moment forces of these bridges are developed in this thesis.