• Uranium exploration methodology in cold climates

      Sims, J.M. (University of Alaska Mineral Industry Research Laboratory, 1980-03)
      The uranium prospecting boom of the past decade had, as a major consequence, the rapid development and proliferation of exploration methods for source materials. Numerous established methods were developed and refined whilst new techniques were introduced proving, in some instances, to be highly successful. To the explorationist the proliferation of instrumental hardware and detection systems was something of a headache with the result that in uranium exploration, more so than in other types of prospecting, the choice of exploration method at the appropriate stage of prospecting was frequently ill founded. The situation also spawned ‘black box’ purveyors who made extravagant claims for their equipment. Money was wasted through over kill applications of exploration method accompanied in many instances by deficiencies in the interpretation of results. This project was originally conceived as a means of evaluating, reviewing and filtering from a burgeoning array of systems the most appropriate exploration techniques applicable to cold climate environments. This goal has been trimmed somewhat since it had been hoped to incorporate site investigation data assembled in the field by the writer as appropriate case history material. This was not possible and as a consequence this report is a 'state of the art review' of the applicability of currently available techniques in Arctic and Subarctic environments. Reference is made to published case history data, where appropriate, supportive of the techniques or methods reviewed.
    • Use of adaptive filtering techniques for estimating low-frequency electromechanical modes in power systems

      Balasubramanian, Ashok (2006-08)
      Information about the location and strength of low frequency electromechanical modes in power systems reflects the stability of the system. Highly recommended and used techniques like Prony analysis and eigenanalysis require ring down from a disturbance and tedious matrix calculations, respectively, for mode estimation. This work proposes the use of the Least Mean Squares (LMS) adaptive filtering algorithms and its combination with other algorithms for estimating and tracking the modes with respect to time. The mode of interest in this work was the 0.26 Hz mode. An Adaptive Step Size Least Mean Squares (ASLMS) algorithm was introduced in this work to reduce variability in mode estimation for non-stationary environments. The ASLMS algorithms achieved quicker convergence than LMS algorithms. A combination of the ASLMS and the LMS algorithm called the Error Tracking (ET) algorithm was tested, based on the running error in the estimate, to reduce variability while also maintaining reasonable convergence time. The ET algorithm achieved high accuracy, less variable performance and quicker convergence of estimates compared to all the other algorithms. The ET algorithm tracked the 0.26 Hz mode in both the simulated data and the real time data with the least amount of error.
    • Use of Cellular Concrete for Air Convection Embankment to Protect Permafrost Foundations in Cold Regions: Feasibility Study

      Liu, Jenny; Wu, Hanli (2019-08-15)
      The air convection embankment (ACE) is a technique used to protect permafrost from thawing in road construction in cold regions. However, the desired materials needed for ACE are not readily available, which prevents its extensive use in Alaska. To overcome the limitation of traditional ACE, and further improve the cooling effect of ACE, this study investigated the feasibility of using cellular concrete as an alternative material for ACE in cold regions. The heat transfer patterns of the cellular concrete ACE, the crushed-rock ACE, and the sand/gravel embankment were studied using the numerical simulation. The results of the present study show that the cooling performance of both cellular concrete ACE and crushed-rock ACE are superior to the traditional sand/gravel embankment. The cellular concrete ACE has better heat insulation property in the summer, and the crushed-rock ACE has stronger natural convection in winter. For the annual cooling efficiency of the two different ACE techniques, the proposed cellular concrete ACE has a better cooling effect on the foundation soil than the crushed-rock ACE. These results indicate that the thermal conductivity and specific heat capacity of construction materials have significant impacts on the performance of the ACE.
    • The use of flocculants to control turbidity in placer mining effluents

      Shen, Yun-Hwei (University of Alaska Mineral Industry Research Laboratory, 1987)
      In this study, two placer mine discharge waters of different characteristics were tested in order to determine the applicability of organic polymer flocculants to achieve reduced levels of turbidity. The water samples from both mines were characterized both as to their chemical and physical properties. The jar test was employed to establish the optimum operation conditions of the flocculation process. The best results were obtained employing a cationic polymer Superfloc 340 produced by American Cyanamid Company. The optimum dosage for water samples from both mines were 15 ppm and 40 ppm respectively. Optimum agitation time was within the range of 3 to 9 minutes depending on the agitation rate and the pulp density of water sample. The utilization of settling ponds, in conjunction with flocculation is believed to be a practical method to control the turbidity level of placer mine discharge water.
    • The Use of Geofiber and Synthetic Fluid for Stabilizing Marginal Soils

      Hazirbaba, Kenan; Connor, Billy; Davis, Duane; Zhang, Yu (Alaska University Transportation Center, 2007)
    • The Use of Geofibers and Synthetic Fluids Kwigillingok Airport

      Collins, Rodney; Connor, Billy (Alaska University Transportation Center, 2011)
    • Use of Geogrids for Limiting Longitudinal Cracking in Roads on Permafrost

      Savage, Bonnie Mae (1991-05)
      Longitudinal cracking of road embankments results from lateral movement of the subbase which creates a subsurface void space. The void spaces propogate to the surface causing cracks and voids. This is hazardous to motorists and expensive to repair. This thesis examines the use of geogrids to limit lateral spreading thereby preserving safe and useable road surfaces. A field experiment, a full-scale laboratory experiment, a soil arching experiment, and behavioral and theoretical analyses are presented. Soil arching forces are quantified and developed using an experiment based on work done by Terzaghi and Kienzl. A theoretical analysis for quantifying the shear force redistribution to be used for geosynthetic embankment systems, was derived from the Soil Arching Experiment. Relationships of load, embankment resistance, deflection and geometric factors are presented. A comparison of geogrid performance to a geotextile performance for the given relationship is presented as well.
    • Use of H2Ri Wicking Fabric to Prevent Frost Boils in the Dalton Highway Beaver Slide Area, Alaska

      Zhang, Xiong; Presler, Wendy (Alaska University Transportation Center, Alaska Department of Transportation and Public Facilities, 2012)
    • Use of the Micro-Deval Test for Assessing Alaska Aggregates

      Liu, Juanyu; Mullin, Anthony; Rein, Jason (Alaska University Transportation Center, Alaska Department of Transportation and Public Facilities, 2012)
    • User interface and function library for ground robot navigation

      Smith, Micah; Lawlor, Orion; Genetti, Jon; Chappell, Glenn (2017-05)
      A web application user interface and function library were developed to enable a user to program a ground robot to navigate autonomously. The user interface includes modules for generating a grid of obstacles from a map image, setting waypoints for a path through the map, and programming a robot in a code editor to navigate autonomously. The algorithm used for navigation is an A* algorithm modified with obstacle padding to accommodate the width of the robot and path smoothing to simplify the paths. The user interface and functions were designed to be simple so that users without technical backgrounds can use them, and by doing so they can engage in the development process of human-centered robots. The navigation functions were successful in finding paths in test configurations, and the performance of the algorithms was fast enough for user interactivity up to a certain limit of grid cell sizes.
    • User's guide for atmospheric carbon monoxide transport model

      Norton, William R.; Carlson, Robert F. (University of Alaska, Institute of Water Resources, 1976-06)
      In the winter months of Fairbanks, Alaska, a highly stable air temperature inversion creates high levels of carbon monoxide (CO) concentrations. As an aid to understanding this problem, a CO transport computer model has been created which provides a useful tool when used in conjunction with other measurement and analytic studies of traffic, meteorology, emissions control, zoning, and parking management. The model is completely documented and illustrated with several examples. Named ACOSP (Atmospheric CO Simulation Program), it predicts expected CO concentrations within a specific geographic area for a defined set of CO sources. At the present time, the model is programmed to consider automobile emissions as the major CO source and may include estimates of stationary sources. The model is coded for computer solution in the FORTRAN programming language and uses the finite-element method of numerical solution of the basic convective-diffusion equations. Although it has a potential for real-time analysis and control, at the present time the model will be most valuable for investigating and understanding the physical processes which are responsible for high CO levels and for testing remedial control measures at high speed and low cost.
    • Using experimental design and response surface methodology to model induced fracture geometry in Shublik shale

      Poludasu, Venkatasai Sri Chand; Ahmadi, Mohabbat; Hanks, Catherine; Awoleke, Obadare (2014-12)
      The Triassic Shublik Formation of the Alaska North Slope is a world-class resource rock and has been identified as the major source of many of the conventional hydrocarbon accumulations on the North Slope, including Prudhoe Bay. Recent interest in the Shublik as a potential shale resource play has highlighted the need for robust hydraulic fracture modeling and simulation of the interval, but little geologic information is available because of the remote nature of the region and the complex character of the Shublik. In this study, a methodology was developed for identifying the critical variables needed for accurate planning of a hydraulic fracturing treatment in a play like the Shublik where much of the geology remains unconstrained. These identified critical variables can be used to develop a proxy model that can be used in lieu of a numerical simulator. This study was conducted in two stages. The first stage used 2-level fractional factorial design to identify the statistical significance of the input variables on the simulated fracture geometry. This stage was conducted in three phases, each phase incorporating progressively more complex assumptions about geology. Using the three most significant variables identified from first stage, the second stage of this study applies Box-Behnken experimental design and response surface methodology for quantifying functional relationships between input variables and the predicted fracture geometry. A pseudo 3D numerical simulator (Fracpro PT) and MATLAB were used to develop proxy models. These proxy models, typically a polynomial equation, are an easier alternative to Fracpro PT and can predict the fracture geometry with very less computational time. The use of experimental design drastically reduces the number of simulations required to evaluate large number of variables. With only 137 simulations, 26 variables were ranked based on their statistical significance and a non-linear proxy model was developed. Predicted values of the fracture geometry obtained using the proxy models were in good agreement with the simulated values of the fracture geometry (R2 value of 99.39% for fracture length, R2 value of 99.54% for fracture height and R2 value of 98.17% for fracture width).
    • Using Geophysical Constraints To Determine Groundwater Travel Times, Seafloor Arrival Locations, And Saltwater Concentrations For Transition Zone Depths At Underground Nuclear Detonations On Amchitka Island

      Wagner, Anna M.; Barnes, David (2007)
      There is a great amount of radioactive material in the subsurface of Amchitka Island as a result from underground nuclear testing performed between 1965 and 1971. It is unknown how long it will take for the radionuclides to travel to the seafloor and the marine environment or where possible seepage zones will occur. The contaminant transport is greatly affected by the location of the transition zone (TZ) and the effective porosity, which were both determined by magnetotellurics (MT) in 2004. The hypothesis of this study was as follows: the groundwater travel times and seafloor arrival locations, can be estimated through groundwater modeling, with the location of the transition zone being estimated by magnetotellurics. An additional hypothesis is as follows: saltwater concentration for a TZ and the general subsurface characteristics can be quantified with groundwater modeling, using geophysical constraints in combination with saltwater and hydraulic head measurements. The groundwater travel times were estimated with groundwater modeling using the transition zone location as determined by MT. Shortest groundwater travel times are 1,200 and 2,100 years, at Long Shot and Cannikin respectively. At Long Shot, a decreased groundwater travel time of up to 55% could be seen when an enhanced hydraulic conductivity was included at the location of an assumed andesite sill layer. The seafloor arrival locations can be up to 1,000 and 2,100 m offshore at Long Shot and Cannikin respectively but will most likely occur closer to shore. This study was also successful at establishing the general characteristics of the subsurface by using geophysical constraints in combination with saltwater and hydraulic head measurements. The subsurface at Long Shot is isotropic or has mild anisotropy ratio of 1:2, which confirms the study by Fenske (1972). As represented in this study, this method has been shown to be valuable in determining the saltwater concentration of the TZ as determined by MT and can thus be used in further studies of islands and coastal areas.
    • Using polyethylene as a coagulant for reducing turbidity from placer mining discharge

      Fan, Ray-Her (University of Alaska Mineral Industry Research Laboratory, 1987)
      Placer gold mining locations on Gilmore and Crooked Creeks in the Fairbanks and Central/Circle, Alaska areas, respectively, were chosen as study sites for evaluation of a unique water treatment process. The physical and chemical impacts on water quality by placer mining were investigated by measuring the pH value, turbidity, and solids content of the slurry samples. Sedimentation tests, zeta potential measurements, and particle size distribution analyses were conducted as well. Also analyzed were mineralogical and chemical composition of the suspended ultrafine particles. Flocculation tests using polyethylene oxide (PEO) with adjunct additives were conducted in the laboratory. Variable parameters such as mixing speed and time, reagent dosages, pH values, as well as synergistic factors were studied. Economic factors and chemical consumption were evaluated and a field treatment plant was designed and proposed.
    • Using rate transient analysis and bayesian algorithms for reservoir characterization in hydraulically fractured horizontal gas wells during linear flow

      Yuhun, Pirayu; Awoleke, Obadare; Ahmadi, Mohabbat; Hanks, Catherine (2019-05)
      Multi-stage hydraulically fractured horizontal wells (MFHWs) are currently a popular method of developing shale gas and oil reservoirs. The performance of MFHWs can be analyzed by an approach called Rate transient analysis (RTA). However, the predicted outcomes are often inaccurate and provide non-unique results. Therefore, the main objective of this thesis is to couple Bayesian Algorithms with a current production analysis method, that is, rate transient analysis, to generate probabilistic credible interval ranges for key reservoir and completion variables. To show the legitimacy of the RTA-Bayesian method, synthetic production data from a multistage hydraulically fractured horizontal completion in a reservoir modeled after Marcellus shale reservoir was generated using a reservoir (CMG) model. The synthetic production data was analyzed using a combination of rate transient analysis with Bayesian techniques. Firstly, the traditional log-log plot was produced to identify the linear flow production regime, which is usually the dominant regime in shale reservoirs. Using the linear flow production data and traditional rate transient analysis equations, Bayesian inversion was carried out using likelihood-based and likelihood-free Bayesian methods. The rjags and EasyABC packages in statistical software R were used for the likelihood-based and likelihood-free inversion respectively. Model priors were based (1) on information available about the Marcellus shale from technical literature and (2) hydraulic fracture design parameters. Posterior distributions and prediction intervals were developed for the fracture length, matrix permeability, and skin factor. These predicted credible intervals were then compared with actual synthetic reservoir and hydraulic fracture data. The methodology was also repeated for an actual case in the Barnett shale for a validation. The most substantial finding was that for all the investigated cases, including complicated scenarios (such as finite fracture conductivity, fracturing fluid flowback, heterogeneity of fracture length, and pressure-dependent reservoir), the combined RTA-Bayesian model provided a reasonable prediction interval that encompassed the actual/observed values of the reservoir/hydraulic fracture variables. The R-squared value of predicted values over true values was more than 0.5 in all cases. For the base case in this study, the choice of the prior distribution did not affect the posterior distribution/prediction interval in a significant manner in as much as the prior distribution was partially informative. However, the use of noninformative priors resulted in a loss of precision. Also, a comparison of the Approximate Bayesian Computation (ABC) and the traditional Bayesian algorithms showed that the ABC algorithm reduced computational time with minimal loss of accuracy by at least an order of magnitude by bypassing the complicated step of having to compute the likelihood function. In addition, the production time, number of iterations and tolerance of fitting had a minimal impact on the posterior distribution after an optimum point--which was at least one-year production, 10,000 iterations and 0.001 respectively. In summary, the RTA-Bayesian production analysis method implemented in relatively easy computational platforms, like R and Excel, provided good characterization of all key variables such as matrix permeability, fracture length and skin when compared to results obtained from analytical methods. This probabilistic characterization has the potential to enable better understanding of well performance, improved identification of optimization opportunities and ultimately improved ultimate recovery from shale gas resources.
    • Using Snow Fences to Augment Fresh Water Supplies in Shallow Arctic Lakes

      Stuefer, Svetlana L. (2013-09)
      This project was funded by the U.S. Department of Energy, National Energy Technology Laboratory (NETL) to address environmental research questions specifically related to Alaska’s oil and gas natural resources development. The focus of this project was on the environmental issues associated with allocation of water resources for construction of ice roads and ice pads. Earlier NETL projects showed that oil and gas exploration activities in the U.S. Arctic require large amounts of water for ice road and ice pad construction. Traditionally, lakes have been the source of freshwater for this purpose. The distinctive hydrological regime of northern lakes, caused by the presence of ice cover and permafrost, exerts influence on lake water availability in winter. Lakes are covered with ice from October to June, and there is often no water recharge of lakes until snowmelt in early June. After snowmelt, water volumes in the lakes decrease throughout the summer, when water loss due to evaporation is considerably greater than water gained from rainfall. This balance switches in August, when air temperature drops, evaporation decreases, and rain (or snow) is more likely to occur. Some of the summer surface storage deficit in the active layer and surface water bodies (lakes, ponds, wetlands) is recharged during this time. However, if the surface storage deficit is not replenished (for example, precipitation in the fall is low and near‐surface soils are dry), lake recharge is directly affected, and water availability for the following winter is reduced. In this study, we used snow fences to augment fresh water supplies in shallow arctic lakes despite unfavorable natural conditions. We implemented snow‐control practices to enhance snowdrift accumulation (greater snow water equivalent), which led to increased meltwater production and an extended melting season that resulted in lake recharge despite low precipitation during the years of the experiment. For three years (2009, 2010, and 2011), we selected and monitored two lakes with similar hydrological regimes. Both lakes are located 30 miles south of Prudhoe Bay, Alaska, near Franklin Bluffs. One is an experimental lake, where we installed a snow fence; the other is a control lake, where the natural regime was preserved. The general approach was to compare the hydrologic response of the lake to the snowdrift during the summers of 2010 and 2011 against the “baseline” conditions in 2009. Highlights of the project included new data on snow transport rates on the Alaska North Slope, an evaluation of the experimental lake’s hydrological response to snowdrift melt, and cost assessment of snowdrift‐generated water. High snow transport rates (0.49 kg/s/m) ensured that the snowdrift reached its equilibrium profile by winter's end. Generally, natural snowpack disappeared by the beginning of June in this area. In contrast, snow in the drift lasted through early July, supplying the experimental lake with snowmelt when water in other tundra lakes was decreasing. The experimental lake retained elevated water levels during the entire open‐water season. Comparison of lake water volumes during the experiment against the baseline year showed that, by the end of summer, the drift generated by the snow fence had increased lake water volume by at least 21–29%. We estimated water cost at 1.9 cents per gallon during the first year and 0.8 cents per gallon during the second year. This estimate depends on the cost of snow fence construction in remote arctic locations, which we assumed to be at $7.66 per square foot of snow fence frontal area. The snow fence technique was effective in augmenting the supply of lake water during summers 2010 and 2011 despite low rainfall during both summers. Snow fences are a simple, yet an effective, way to replenish tundra lakes with freshwater and increase water availability in winter. This research project was synergetic with the NETL project, “North Slope Decision Support System (NSDSS) for Water Resources Planning and Management.” The results of these projects were implemented in the NSDSS model and added to the annual water budget. This implementation allows one to account for snowdrift contributions during ice road planning with the NSDSS and assists with mitigating those risks associated with potentially unfavorable climate and hydrological conditions (that is, surface storage deficit and/or low precipitation).
    • Using SuperDARN to predict polar irregularities that cause GPS scintillation

      Simon, Michelle R.; Bristow, William; Hawkins, Joe; Thorsen, Denise (2016-12)
      High levels of scintillation caused by strong magnetic storms can cause GPS devices to lose connection with the necessary satellites. Current research has shown a correlation between major magnetic storms and higher levels of the recorded Total Electron Content (TEC) seen in GPS receivers. The research presented in this thesis examines the idea that observations from the Super Dual Auroral Radar Network (SuperDARN) can be used to predict scintillation levels in GPS receivers at polar latitudes by using GPS scintillation values σφ and S4 that were collected from January, 2013 till November, 2015. These values were gathered from Poker Flat, Alaska, and McMurdo Station, Antarctica. Using various graphical methods the GPS data was compared with the recorded velocity, power and spectral width measurements from Kodiak, Alaska, and South Pole, Antarctica, SuperDARN sites. The SuperDARN values were ignored in the comparison if they did not fall within the specified GPS field of view, they were tagged with a ground scatter flag, or the data quality flag indicating they were erroneous. These bar and scatter graphs indicate that many of the irregularities identified by SuperDARN do not cause scintillation of a GPS signal. When the GPS scintillation variables are examined as a function of the SuperDARN signal parameters (power, velocity, and spectral width) only a small dependence is shown, demonstrating little correlation between the GPS scintillation variables and SuperDARN's variables. Based on these results SuperDARN cannot be used to predict higher levels of GPS scintillation in polar latitudes.
    • Using the generalized interpolation material point method for fluid-solid interactions induced by surface tension

      Chen, Liangbiao; 陈 良彪; Lee, Jonah; Lee, Jonah; Chen, Cheng-fu; Kim, Sun Woo; Misra, Debasmita (2013-12)
      This thesis is devoted to the development of new, Generalized Interpolation Material Point Method (GIMP)-based algorithms for handling surface tension and contact (wetting) in fluid-solid interaction (FSI) problems at small scales. In these problems, surface tension becomes so dominant that its influence on both fluids and solids must be considered. Since analytical solutions for most engineering problems are usually unavailable, numerical methods are needed to describe and predict complicated time-dependent states in the solid and fluid involved due to surface tension effects. Traditional computational methods for handling fluid-solid interactions may not be effective due to their weakness in solving large-deformation problems and the complicated coupling of two different types of computational frameworks: one for solid, and the other for fluid. On the contrary, GIMP, a mesh-free algorithm for solid mechanics problems, is numerically effective in handling problems involving large deformations and fracture. Here we extend the capability of GIMP to handle fluid dynamics problems with surface tension, and to develop a new contact algorithm to deal with the wetting boundary conditions that include the modeling of contact angle and slip near the triple points where the three phases -- fluid, solid, and vapor -- meet. The error of the new GIMP algorithm for FSI problems at small scales, as verified by various benchmark problems, generally falls within the 5% range. In this thesis, we have successfully extended the capability of GIMP for handling FSI problems under surface tension in a one-solver numerical framework, a unique and innovative approach.
    • Using the USDA wind erosion equation for comparative modeling of natural and anthropogenic sources of particulates measured at the Fort Greely PM₁₀ monitoring station, Alaska, a case study

      Becker, Steven R.; Perkins, Robert; Barnon, David; Whitaker, Keith; Aggarwal, Srijan (2015-05)
      In April of 2010, the Alaska Department of Environmental Conservation (ADEC) opened a compliance case against the U.S. Army Garrison Fort Greely, Alaska (FGA), for then repeated failure to comply with a permit condition requiring the collection of one year of Prevention of Significant Deterioration (PSD)-quality data on ambient levels of particulate matter less than 10 microns in effective aerodynamic diameter (PM₁₀). During the monitoring period of 2012-2013, background levels of PM₁₀ were more than 80% the Alaska Ambient Air Quality Standards (AAAQS) for a total of seven days in the winter of 2012-2013. On March 17, 2014, ADEC requested that FGA provide substantive documentation that PM₁₀ exceedances observed during the monitoring period were of natural provenance and not from anthropogenic sources. In response to this request, the author used Geographic Information System (GIS) technology to analyze basic meteorological data and outputs from the USDA Wind Erosion Equation (WEQ) to generate a simple back-trajectory model for determining the sources and relative contributions to PM₁₀ experienced at a given receptor. Using this model, the author was able to show that the vast majority of PM₁₀ at Fort Greely was natural rather than anthropogenic in nature. The ADEC Division of Air Quality determined that results of this study constituted substantive documentation that PM₁₀ exceedances observed during the monitoring period were of natural provenance and not from anthropogenic sources, and issued a compliance case closure letter on June 20, 2014. In addition to the direct results of the study, the project also serves to demonstrate a low-complexity model that can be used to assess the relative contribution of anthropogenic and natural sources of PM₁₀ at a given receptor. Additionally, it can be used in complex situations as a screening tool to focus data collection efforts on significant sources of PM₁₀ and facilitate the prioritization of PM₁₀ sources for more precise quantitative dispersion or receptor models when precise quantitative data are required.
    • Utilization of Screw Piles in High Seismicity Areas of Cold and Warm Permafrost

      Hazirbaba, Kenan; Cox, Brady; Wood, Clinton (Alaska University Transportation Center, University of Arkansas, 2010)