Theses for the College of Engineering & Mines

Recent Submissions

  • Hydrodynamics of downstream pointed guidevanes: a case study of the Hess Creek meander bend realignment

    Lai, Alexandre W. (2011-12)
    The hydrodynamics of downstream pointed guidevanes installed to realign an eroding meander bend upstream of the Trans- Alaska Pipeline bridge is studied. The bridge is located at Hess Creek, 137 km north of Fairbanks, Alaska. Effect of the downstream pointed vanes on bed form, erosion, longitudinal and transverse slopes, three dimensional velocity profiles, flow patterns, and other hydraulic parameters for high and low flows are compared and analyzed. Six years after installation of the vanes the realigned thalweg remains in its original design location. The longitudinal bed profile changed from a dominant continuous pool typical of natural meander bends on gravel stream beds to a series of pool riffles. However, there is minimal change in maximum scour depth between post and pre installation of the vanes. Secondary or transverse current patterns which cause scour or erosion on the outer bank are severely disrupted due to interference caused by the vanes. There is a consistent weak counter current in reaches between the vane stems due to flow separation caused by expansion of flow area. This condition was more dominant during low flows when the vanes were not completely submerged. From the tip of the vanes to the inner bank a more dominant transverse and streamwise current was measured. Location of the original eroding outer bank remains unchanged since installation of the vanes. This indicates that the vanes have to this point effectively realigned the meander bend and arrested additional lateral movement of the meander.
  • Engineering economic analysis of a rail extension from Dunbar siding to Livengood, Alaska

    Bohart, Charles W.; Metz, Paul A.; Huang, Scott L.; Misra, Debasmita (2011-12)
    The Dunbar Siding to Livengood rail extension study is an economic prefeasibility investigation, and is conducted from two perspectives as a cost benefit analysis. The first perspective is, that of the Alaska Railroad Corporation (ARRC) in which the capital and operating costs of the proposed extension are recovered through the revenue stream resulting from the out-bound mineral freight loads, the in-bound re-supply freight loads, and the potential commuter passenger service to mining projects and communities in the Livengood area. The second perspective is that of the private sector in which a shipping sensitivity and employee transport analysis with respect to mining project developments. The large mineral resource base within the Dunbar-Livengood Corridor indicates an excellent freight potential with generous benefits for Alaska's economy of greater than $2 billion annually in gross revenues; whereas, resource and rail development are synergistic.
  • Interferometric modification of the Lockheed Martin PSTAR system to facilitate three dimensional airspace surveillance

    Otterbacher, Scott E. (2011-05)
    The Lockheed Martin PSTAR is a monostatic radar system that provides range, azimuth, and radial velocity information of detected targets. While this system is useful for airspace surveillance in remote locations due to its portability and durability, it lacks the ability to record target information and the ability to estimate target elevation angle, resulting in a vertical arc of possible target locations. Due to a desire to use the PSTAR for applications that require logging three-dimensional target information, a spatial interferometric modification has been implemented. The PSTAR estimates range from pulse propagation delay and azimuth angle from the orientation of the antenna on a rotating pedestal. Two PSTAR antennas were removed from their housings and mounted, vertically separated, in a custom enclosure allowing for the estimation of elevation angle through spatial interferometry. The reflected signal is received by both antennas, mixed to baseband, and then the two pairs of I/Q channels are simultaneously sampled at 1 MS/s. Target elevation angle is estimated by determining the phase difference of the target's reflection received by the two vertically spaced antennas. Range, azimuth, and radial velocity are also estimated. All data collection was implemented in LabVIEW and data post-processing was implemented in MATLAB.
  • Investigation of the friction and noise of automotive rubber belt

    Narravula, Vikram R. (2011-05)
    The objective of this research was to study the frictional properties of an automotive v-ribbed belt-pulley system. In order to evaluate the friction and noise, a new test setup was constructed. The assembly was run under various environmental and operational conditions and the results were quantified, studied, and compared among themselves. The environmental conditions included dry interface and wet interface, conducted at both room temperature (23°C) and cold temperature ( -20°C). Operational parameters varied during the experiment were wrap angle, load attached, and acceleration. Frictional forces and associated noises generated were recorded. Some of the results generated were compared with previous research work, and the setup was also used to generate new data for conditions not previously studied. Dry room temperature results show close correlation with previous research. The presence of water in liquid state in the interface induces larger adhesion as water film in the interface changes friction mechanisms in the rubber belt-pulley interface. The high stiction of wet friction can lead to stick-slip vibrations and squeal noise. The theoretical stiction model for wet belt-pulley interface is presented. The stiction-related noise test is conducted, and the result is used to identify the spectrum pattern. The belt friction under cold conditions is found to have a higher value than that in room temperature conditions. The belt noise under cold conditions is found to have much higher squeal frequency than that in room temperature conditions.
  • The measurement of anisotropic thermal conductivity in snow with needle probes

    Holbrook, Joshua (2011-05)
    A new method for measuring thermal conductivity is being adapted from the method of measuring isotropic thermal conductivity in snow with needle probes as used by Sturm, Johnson and others, in order to enable the determination of anisotropic thermal conductivities. This method has particular relevance to measuring thermal conductivity of natural snowpacks where conductivity can be strongly anisotropic due to structures that develop from vapor transport-induced metamorphism, self-compaction and other mechanisms, and where there are known discrepancies between density-conductivity relations empirically derived from guarded hot plate and needle probe methods. Both analytically-based solutions and finite element numerical solutions to the anisotropic case are used to calculate the expected effective thermal conductivity as a function of anisotropic thermal conductivity and needle orientation. Additionally, preliminary measurements of both anisotropic salt/sugar layered samples and of snow were taken. Both suggest that detecting anisotropy in such materials is possible, though made difficult by variability between measurements and the requirement of multiple measurements at various angles. These studies suggest that anisotropy in snow may be able to explain in part the discrepancies between guarded hot plate and needle probe measurements in certain cases.
  • Creep of grouted anchors in ice-rich silt

    Chen, Liangbiao (2011-05)
    Creep is a critical consideration for designing anchors in ice-rich silt. In this study, creep was evaluated for grouted anchors in ice-rich silt by laboratory tests. A total of nineteen staged-load pullout tests were conducted on smooth grouted anchors. The anchors were loaded until either a tertiary creep stage or the capacity of the load system was reached. Soil temperatures evaluated in this study ranged from 32 °F to 26.6 °F. It was found that the onset of tertiary creep for smooth anchors was around 0.03 inches, which was much smaller than that suggested in the literature for rough anchors (1.0 inch). Given the same shear stress and soil temperature, the observed creep displacement rates for smooth anchors were greater than those given by the existing design guidelines for rough anchors. A new creep model was proposed in which soil temperature was included as an additional variable. Model parameters were developed as a function of soil temperature and moisture contents by using the test data. The model predictions were compared with the laboratory tests. It was found that the creep displacement rates decreased with the decreasing of soil moisture contents and temperature. Based on the analysis of laboratory test data, design charts were provided to give the allowable pullout capacity for smooth anchors in ice-rich silt.
  • Attenuation of the herbicide glyphosate along railroad corridors in Alaska

    Ballou, Nellie B. (2011-05)
    Following the application of glyphosate in the formulation of AquaMaster® at two contrasting sub-arctic zones along the railroad corridor in Alaska, attenuation of the herbicide glyphosate was investigated. Study sites were established in continental and coastal zones. Glyphosate soil attenuation was similar to temperate regions during the growing season but exhibited an extended persistence during the winter months. Although glyphosate microbial degradation likely slowed during winter, both sites showed evidence of slight glyphosate degradation during the winter months. The coastal site attenuated more rapidly than the continental site which is presumably due to increased rainfall relative to the continental site. Glyphosate attenuation at the coastal site was likely driven by dispersion while microbial degradation was responsible for the attenuation of glyphosate at the continental site. Movement to subsurface soils (10-25 cm) at low concentrations was observed at both sites with slightly more transport at the coastal site than the continental site. Glyphosate transport to groundwater along railroad corridors was not conclusive. Vegetation cover reduction was reduced at the continental site but could not be determined at the coastal site.
  • Design of a micro-hydrokinetic electric power generation system

    Han, Rui (2011-08)
    The objective of this thesis project is to design a Micro-Hydrokinetic Power Generating (MHPG) system to generate electricity from sustainable and distributed hydrokinetic resources. The system is developed from a patent held by one of our team members, Robert Kallenberg. The MHPG does not require a dam or diversion, thus avoiding the negative environmental impacts associated with dams. The project could also help some communities to make use of their locally available hydrokinetic resources and significantly reduce their electricity costs. Reviewing of the literature in hydrokinetic electric power generation technology shows that hydrokinetic projects developed to date have largely made use of hydro turbine systems. These hydro turbines have a strong potential to cause fish mortality, while by design, the MHPG has little chance of causing mortality due to its gentle motion. On the other hand, the build-up of debris on a conventional hydro turbine can easily disable or even destroy the turbine, while the hydro foil in our device is generally oriented with the angle of attack less than 30 degree from the current, keeping debris build up at a minimum. The state of the art software COMSOL Multiphysics has been used as our numerical analysis tool. The interaction of water and the designed foil in a straight rectangular turbulent channel is modeled, explicitly, using two conservation laws: conservation of momentum and conservation of mass. The incompressible Navier-Stokes application mode in COMSOL Multiphysics has been used in this simulation to solve the distribution of the pressure and the velocity filed. Results show that the oscillating hydro foil has the potential to surpass the efficiency of a conventional turbine, and is deployable in relatively low velocity streams. Future project development suggestions will be presented focusing on further improvements electric machinery design and system integration. Finally, the prototype of the device has been fabricated and tested in natural rivers. The first test in Chena River, AK, verified the design by showing that the prototype can move in an oscillating manner. The second test in San Gabriel River, CA, shown that the designed Scotch Yoke, which was used to convert linear motion into rotational motion, could be efficiently integrated with the motion generation system. Future test work including permanent magnetic generator coupling and energy efficiency measurement need to be carefully studied concerning the system efficiency and maintenance.
  • Potential recharge estimates of Arctic lakes to aid water management on the North Slope of Alaska

    Cormack, Chad Michael (2011-08)
    Water is a valuable asset to the petroleum industry on the North Slope of Alaska. Current water-permitting processes do not take into account watershed principles in the allocation of water resources. This has primarily been due to lack of information related to tundra lake watersheds and associated water use. This thesis evaluated several study lakes located within the eastern portion of the National Petroleum Reserve Alaska (NPRA) to demonstrate how watershed and meteorological parameters could be incorporated into water-use management practices. Watershed areas were delineated for the study lakes digitally with geographic information systems (GIS) and Rivertools software. Estimates for rainfall, snow-water equivalent, and evapotranspiration were combined to calculate potential recharge estimates for each individual study lake. A potential recharge tool was developed to help calculate potential recharge values. This tool can be a good first step for industry to begin to apply watershed principles into the water-permitting processes. For the study lakes analyzed, it was concluded that water withdrawal would not adversely affect the sustainability of the water bodies. With the current level of available data, recharge estimates are accurate enough to be used in permitting processes. It is recommended that geographic lake parameters (i.e., watershed and lake areas) and meteorological parameters (e.g., rain, snow, evapotranspiration) are further studied and included in future lake permits.
  • Stabilization of marginal soils using geofibers and nontraditional additives

    Collins, Rodney Wotherspoon (2011-08)
    Western Alaska lacks gravel suitable for construction of roads and airports. As a result, gravel is imported, at a cost of between $200 and $600 per cubic yard, to fill transportation construction needs. In an effort to reduce these costs, the Alaska University Transportation Center (AUTO) began searching for methods to use local materials in lieu of imported gravel. The approach discussed in this thesis uses geofibers and chemical additives to achieve soil stabilization. Geofibers and chemical additives are commercially available products. The goal of the research presented in this thesis is to test the impact of addition of two geofiber types, six chemical additives, and combinations of geofibers with chemical additives on a wide variety of soil types. California Bearing Ratio (CBR) testing was used to measure the effectiveness of the treatments. Soils ranging from poorly graded sand (SP) to low plasticity silt (ML) were all effectively stabilized using geofibers, chemical additives, or a combination of the two. Through the research conducted a new method of soil stabilization was developed which makes use of curing accelerators in combination with chemical additives. This method produced CBR values above 300 for poorly graded sand after a seven day cure.
  • Water-in-air droplet formation in plasma bonded microchannels fabricated by Shrinky-Dink® lithography

    Bender, Christopher J. Jr. (2011-08)
    This thesis presents the first work on water-in-air droplet microfluidics. Polymeric microchannels were prototyped to illustrate water droplet formation in air by the T-junction meditated design. The first part of the thesis is on the proof of using unfiltered air as the process gas for plasma-assisted bonding of polydimethylsiloxane (PDMS) microchannels. A series of bilayered PDMS prototypes were plasma bonded under various plasma treatment parameters to determine the optimal settings for high-strength bonding. Pressure rupture tests were conducted to measure the bonding interface strength, which were shown to be as high as 135 psi. The second part of the thesis illustrates the formation and dispersion of water droplets in a continuous air flow in microchannels, and discusses the mechanisms of how droplets are formed. The Shrinky Dinks lithography and plasma-assisted bonding were used to prototype leakage-free microcbannels for testing droplet production. Droplets are formed under the competition between the fluid viscosity and surface tension forces. The channel dimensions and the fluid flow rates dictate the mechanism of droplet formation. The major finding is that the droplet length increases and droplet velocity decreases with increasing water flow rates, but some droplets were not formed at the T-Junction. These findings are discussed.
  • Characterizing the berthing load environment of the Seattle ferry teminal, Bremerton slip

    Kwiatkowski, Jason E. (2012-12)
    This manuscript characterizes and presents design recommendations for berthing demands on ferry landing structures. There is a lack of research focused on the berthing load demand imparted by ferry class vessels, therefore the load criteria used for design is often based on a number of assumptions. This study involved a one-year field study of the structural load environment of wingwalls at the Bremerton Slip of the Seattle Ferry Terminal, located in Elliott Bay adjacent to Seattle, Washington. Measurements of marine fender displacement, vessel approach distance with respect to time, and. pile strain were used to determine berthing demands. Berthing event parameters were characterized using the Python programming language, compiled, and analyzed statistically. Probability theory was used to provide design value recommendations for berthing energy, force, approach velocity, berthing factor, and berthing coefficient. This study presents a number of engineering design aids intended to quantify the berthing load environment of wingwalls in the Washington State Ferry System.
  • Evaluating dust palliative performance and longevity using the UAF-DUSTM

    Eckhoff, Travis Warren; Milne, Clark (2012-12)
    Fugitive dust emissions from gravel surfaces such as unpaved roads and airport runways are a major source of particulate matter pollution in the environment. Fugitive dust emissions impact community health, decrease visibility and contribute to surface degradation. Chemical additives, also known as dust palliatives, are often used to reduce these dust emissions. Although these products have been widely used, little is known about their effectiveness and longevity. There is currently no standard test method to quantify the reduction in fugitive dust emissions provided by dust palliatives. The UAF-DUSTM was developed to provide a consistent test method for determining the effectiveness and longevity of dust palliative applications. Dust palliatives applications throughout Alaska were monitored for several years. The results show that dust palliatives can significantly reduce particulate matter emissions and be effective for several years.
  • The impact of a fluctuating freezing front on ice formation in freezing soil

    Dillon, Matthew Ryan (2012-12)
    Frost heave is typically associated with the formation of segregation ice in fine-grained soil. Coarse-grained soil is generally considered to be non-frost susceptible. Field observa-tions and laboratory experiments show that coarse-grained soil can be extremely ice-rich in specific conditions. Previous studies have shown that oscillation of the frozen-unfrozen boundary can lead to the formation of ice by a mechanism different from the segregation ice mechanism. Conditions related to the formation of ice in coarse-grained soil were in-vestigated using modern laboratory techniques. Fourteen tests were conducted on five soil types. The thickness of soil subjected to freeze-thaw cycles was varied and controlled by the magnitude and duration of applied soil temperatures. The thickness of the ice formed increased when the sample drainage was limited or prevented during cooling. Under spe-cific conditions, the formation of a discrete ice layer was observed in coarse-grained soils. Seven samples were scanned with the pCT scanner at the completion of the warming and cooling tests. The sub-samples scanned were analyzed in 2D cross-sections, and charac-terized as 3D reconstructions. Frost heave induced by the formation of ice was observed in both fine- and coarse-grained soils, including soils that were found to be traditionally non-frost susceptible.
  • High-latitude over-the-horizon radar applications

    Theurer, Timothy E.; Bristow, William; Thorsen, Denise; Hawkins, Joseph; Watkins, Brenton (2020-05)
    Over-the-horizon radar (OTHR) systems that operate at high-latitudes often must contend with multipath and pronounced diffusive scattering effects produced by the anisotropic, birefringent, and heterogeneous nature of the ionosphere. In this thesis, radar performance at high-latitudes is quantified and several applications for either mitigating the deleterious effects of multipath and diffusive scattering or deriving information about the state of the ionosphere are proposed. The first application is inspired by adaptive optics techniques in other fields and involves the coherent summation of the received plane wave spectrum in order to improve angular resolution and array gain. The second application involves deriving ionospheric E x B drift from applying spatial correlation analysis to ground clutter echoes. The third application is the development of a new spatial adaptive processing technique designed specifically to preserve the Doppler spectrum of angle-Doppler coupled clutter like that observed at high-latitudes.
  • Renewable energy development in Alaska: policy implications for the development of renewable energy for remote areas of the circumpolar Arctic

    Holdmann, Gwen Pamela; Johnson, Ronald; Peterson, Rorik; Greenberg, Joshua; Sfraga, Mike (2019-12)
    The territories that comprise the Arctic region are part of some of wealthiest and most advanced countries on the planet; yet, rural Alaska, northern Canada, the Russian Far East and Greenland--characterized by off-grid communities, regional grids, and higher degrees of energy insecurity--have more in common with the developing world than the southern regions of their own country. This thesis explains this paradox of energy development in the Circumpolar North and tackles the issue of developing renewable energy in remote areas where technical and socioeconomic barriers are significant. The primary research questions are two-fold: 1) Why did the Alaska electrical system develop as a non-integrated patchwork of regional and isolated grids? and 2) What are the major factors in Alaska that have resulted in a greater uptake of renewable energy systems for remote communities, compared to other similar places in the Arctic? This thesis demonstrates that state-building theory provides a cogent framework to understand the context of electrical build-out in the Circumpolar North. A major finding of this thesis is that the buildout of electric infrastructure in the non-Nordic countries, including Alaska, exemplifies a process of incomplete nation-building. Interconnected regional grids, where they exist, are largely due to the twin national priorities in infrastructure development in the north: extracting natural resources and enhancing national security. This thesis also draws on sociotechnical transition theory to explain why Alaska exhibits such high levels of energy innovation when compared to other similar regions across the Arctic. This research concludes that drivers such as extremely high energy costs, a highly deregulated utility market with dozens of certificated utilities, state investment in infrastructure, and modest subsidies that create a technological niche where renewable energy projects are cost-competitive at current market prices have spurred energy innovation throughout Alaska's communities, remote or otherwise. Many of the evolving technical strategies and lessons learned from renewable integration projects in Alaska's remote islanded microgrids are directly applicable to project development in other markets. Despite differences in climate and geography, lessons learned in Alaska could prove invaluable in increasing resiliency and driving down energy costs in remote communities world-wide.
  • Application of design of experiments for well pattern optimization in Umiat oil field: a natural petroleum reserve of Alaska case study

    Gurav, Yojana Shivaji; Dandekar, Abhijit; Patil, Shirish; Khataniar, Santanu; Clough, James; Patwardhan, Samarth (2020-05)
    Umiat field, located in Alaska North Slope poses unique development challenges because of its remote location and permafrost within the reservoir. This hinders the field development, and further leads to a potential low expected oil recovery despite latest estimates of oil in-place volume of 1550 million barrels. The objective of this work is to assess various possible well patterns of the Umiat field development and perform a detailed parametric study to maximize oil recovery and minimize well costs using statistical methods. Design of Experiments (DoE) is implemented to design simulation runs for characterizing system behavior using the effect of certain critical parameters, such as well type, horizontal well length, well pattern geometry, and injection/production constraints on oil recovery. After carrying out simulation runs using a commercially available simulation software, well cost is estimated for each simulation case. Response Surface methodology (RSM) is used for optimization of well pattern parameters. The parameters, their interactions and response are modeled into a mathematical equation to maximize oil recovery and minimize well cost. Economics plays a key role in deciding the best well pattern for any field during the field development phase. Hence, while solving the optimization problem, well costs have been incorporated in the analysis. Thus, based on the results of the study performed on selected parameters, using interdependence of the above mentioned methodologies, optimum combinations of variables for maximizing oil recovery and minimizing well cost will be obtained. Additionally, reservoir level optimization assists in providing a much needed platform for solving the integrated production optimization problem involving parameters relevant at different levels, such as reservoir, wells and field. As a result, this optimum well pattern methodology will help ensure optimum oil recovery in the otherwise economically unattractive field and can provide significant insights into developing the field more efficiently. Computational algorithms are gaining popularity for solving optimization problems, as opposed to manual simulations. DoE is effective, simple to use and saves computational time, when compared to algorithms. Although, DoE has been used widely in the oil industry, its application in domains like well pattern optimization is novel. This research presents a case study for the application of DoE and RSM to well optimization in a real existing field, considering all possible scenarios and variables. As a result, increase in estimated oil recovery is achieved within economical constraints through well pattern optimization.
  • Stress-corrosion cracking susceptibility of polystyrene/TiO₂ nanocomposite coated thin-sheet aluminum alloy 2024-T3 with 3.5% NaCl

    Baart, Brian V.; Chen, Cheng-fu; Ahn, Il Sang; Zhang, Lei (2020-05)
    This thesis reports an investigation into the performance of nanocomposite coatings, which consist of titanium dioxide nanoparticles within a polystyrene matrix, on the resistance to stress-corrosion cracking (SCC). The coatings are applied to compact tension specimens subject to conditions that promote failure by (SCC). It has been well documented in the literature that high-strength aluminum alloys such as 2024- T3 are prone to SCC when exposed to chloride media and sufficient levels of stress. The use of polymerbased nanocomposite coatings to protect aluminum alloy 2024-T3 has recently been shown to exhibit anticorrosion properties, which has been motivation for further study. The performance of such coatings on SCC is thus investigated here, using a fracture mechanics approach with compact tension specimens. The specimens are subject to a slow strain rate test using a constant displacement rate of 1.25 nm/s while exposed to periodically supplied 3.5% wt. sodium chloride solution. Measurements of load and crackmouth opening displacement data are recorded from the specimen throughout the test and used to characterize the response of the material to the applied mechanical loading in a corrosive environment. Results from the methods used herein showed a quantitative influence derived from the test results for several criteria of interest such as maximum load, time-to-failure, and fracture toughness. In total, four different coatings were applied; three with different titanium dioxide nanoparticle aspect ratios, and one without any titanium dioxide nanoparticles present in the polystyrene matrix. Characterization of the results showed that the shape of the titanium dioxide nanoparticle is a dominant factor that influences the susceptibility of aluminum alloy 2024-T3 to SCC.
  • Laboratory investigation of infiltration process of nonnewtonian fluids through porous media in a non-isothermal flow regime for effective remediation of adsorbed contaminants

    Naseer, Fawad; Misra, Debasmita; Metz, Paul; Awoleke, Obadare; Najm, Majdi Abou (2019-12)
    Contamination of soil and groundwater have serious health implications for man and environment. The overall goal of this research is to study a methodology of using nonNewtonian fluids for effective remediation of adsorbed contaminants in porous media under nonisothermal flow regimes. Non-Newtonian fluids (Guar gum and Xanthan gum solutions) provide a high viscous solution at low concentration and these fluids adjust their viscosities with applied shear rate and change in temperature. Adjustment of viscosity with an applied rate of shear is vital for contaminant remediation because non-Newtonian shear thinning fluids can penetrate to low permeability zones in subsurface by decreasing their viscosities due to high shear rates offered by low permeability zones. The application of non-Newtonian shear thinning fluids for contaminant remediation required the improvement in understanding of rheology and how the factors such as concentration, temperature and change in shear rate impacted the rheology of fluids. In order to study the rheology, we studied the changes in rheological characteristics (viscosity and contact angle) of non-Newtonian fluids of different concentrations (i.e., 0.5g/l, 1g/l, 3g/l, 6g/l and 7g/l) at different temperatures ranging from 0 ºC to 30 ºC. OFITE model 900 viscometer and Tantec contact angle meter were used to record the changes in viscosity of fluids for an applied range of shear rate (i.e., 17.02 s⁻¹ to 1021.38 s⁻¹) and contact angles, respectively, for different concentrations of non-Newtonian fluids. Understanding the flow characteristic of non-Newtonian fluids under low temperature conditions could help in developing methods to effectively remediate contaminants from soils. Results of rheological tests manifested an increase in the viscosity of both polymers with concentration and decrease in temperature. Mid (i.e., 3g/l) to high (i.e., 6g/l and 7g/l) concentrations of polymers manifested higher viscosities compared to 0.5g/l for both polymers. Flow of high viscous solutions required more force to pass through a glass-tube-bundle setup which represented a synthetic porous media to study the flow characteristic and effectiveness of Newtonian and non-Newtonian fluids for contaminant remediation. Low concentrations of 0.5g/l were selected for flow and remediation experiments because this concentration can flow through porous media easily without application of force. The 0.5g/l of Xanthan gum and de-ionized water were used to conduct the infiltration experiments to study the flow characteristics of Newtonian and non-Newtonian fluids at 0.6°C, 5°C and 19°C in synthetic porous media. Infiltration depth of both Newtonian and non-Newtonian fluids would decrease with the decrease in temperature because of the change in their properties like dynamic viscosity, density and angle of contact. The result of comparison of Newtonian and non-Newtonian fluids showed water to be more effective in remediating a surrogate adsorbent contaminant (Dichlobenil) from the synthetic porous media at 19°C. This result was counter-intuitive to what we began with as our hypothesis. However, it was also observed later that 0.5 g/l concentration of Guar gum behaved more like a Newtonian fluid and 0.5 g/l concentration of Xanthan gum had not shown strong non-Newtonian behavior compared to higher concentrations of Xanthan gum. Hence more analysis needs to be done to determine what concentration of non-Newtonian fluid should be more effective for remediation.
  • Retrodirective phased array antenna for nanosatellites

    Long, Justin W.; Thorsen, Denise; Kegege, Obadiah; Hawkins, Joseph; Mayer, Charles (2019-12)
    This thesis presents a S-band phased array antenna for CubeSat applications. Existing state-of the-art high gain antenna systems are not well suited to the majority of CubeSats, those that fall within the 1U (10 cm x 10 cm x 10 cm) to 3U (10 cm x 10 cm x 30 cm) size ranges and in Low Earth Orbit (LEO). The system presented in this thesis is designed specifically to meet the needs of those satellites. This system is designed to fit on the 1U face (10 cm x 10 cm) of a CubeSat and requires no deployables. The use of beamforming and retrodirective algorithms reduces the pointing requirements of the antenna, easing the strict requirements that high gain antennas typically force on a CubeSat mission. Additionally, this design minimizes volume and uses low cost Commercial-off-the-Shelf (COTS) parts. This thesis discusses the theoretical background of phased array theory and retrodirective algorithms. Analysis are presented that show the characteristics and advantages of retrodirective phased antenna systems. Preliminary trade studies and design analyses show the feasibility and expected performance of a system utilizing existing COTS parts. The preliminary analysis shows that an antenna system can be achieved with ≥8.5 dBi of gain, 27dB of transmitted signal gain, 20% Power Added Efficiency (PAE) within a 1 W to 2 W power output, and an 80° effective beamwidth. Simulation results show an example antenna array that achieves 8.14 dBi of gain and an 82° effective beamwidth. Testing results on a prototype of the front-end electronics show that with minimal calibration, the beamforming and scanning error can be reduced to 5°. The power consumption and signal gain of the electronics is also verified through testing. The CubeSat Communications Platform, a CubeSat mission funded through the Air Force Research Laboratory is in Phase A design to demonstrate this antenna system, along with other experimental payloads. This thesis includes a discussion of interface control, mission requirements, operations, and a recommended experiment sequence to test and verify the antenna system on orbit.

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