Recent Submissions

  • A web interface for Clearpath unmanned ground vehicle navigation, mapping, and control

    Randle, Daniel P.; Hatfield, Michael; Raskovic, Dejan; Lawlor, Orion (2023-05)
    This project aims to restore and upgrade the UAF Clearpath platform assets, develop a web application for visualization and control, and document the process. The platforms were upgraded with the latest Clearpath Linux distributions and ROS packages, and their base stations were restored with correctly configured routers. A web application was created to provide convenient visualization and control of the UGVs through a user interface tuned for desktop and smartphone web browsers. The system allows for full control/visualization and read-only visualization through different endpoints, with driving and autonomous navigation features available through the control endpoint. The system also provides a two-dimensional map with the robot and obstacles localized on the map, and an interface for setting autonomous navigation goals. The project was thoroughly documented, and the source code and documents will remain available on GitHub for future use. The system is easily extendable and customized, allowing for the development of new navigation algorithms, user interface features, and endless other possible future projects involving Clearpath platforms.
  • Calculation of sublimation from tundra snowpack in Alaska

    Stockert, Kelsey; Stuefer, Svetlana; Euskirchen, Eugenie; Schiewer, Silke (2022-05)
    Snow sublimation is the direct transfer of water between the snowpack and the atmosphere, playing a fundamental role in the winter water balance. To date, there are few studies that quantify sublimation by direct measurements. This study uses Eddy Covariance (EC) data from 2010 to 2020 to calculate sublimation from three locations within Imnavait Creek watershed, a small Arctic watershed (2.2 km2) located on the North Slope of Alaska. EC fundamentally measures only surface sublimation, which underestimates total sublimation since it does not consider sublimation from blowing snow. Complementary data were collected at each EC measurement site and analyzed in addition to data from a nearby meteorological station, a borehole, and annual spring snow surveys that measure site environmental conditions and evaluate controls on sublimation rates. For the seven-year time series, mean surface sublimation rates ranged from 0.06-0.07 mm day-1 and 13-16 mm year-1 among the three sites. Linear regressions show that the strongest drivers of sublimation are wind speed, air temperature, vapor pressure deficit, and temperature gradient in this Arctic watershed. The watershed average cumulative annual sublimation rates have significant linear relationships to the duration of above freezing temperatures in the soil active layer, snow cover duration, and number of precipitation days. On average, 11% of the end-of-winter snowpack was returned to the atmosphere by sublimation. The fraction of sublimation from the total winter precipitation is comparable to results reported in the literature by the same method, but daily rates are significantly lower. The findings of this study are an important contribution to the sparse literature on Arctic sublimation measurements and will benefit scientists in their understanding of how site conditions affect sublimation rates and the winter hydrologic cycle.
  • Design of a solar assisted flying wing small unmanned aerial system

    Alioto, Zion A.; Peterson, Rorik A.; Hatfield, Michael C.; Denkenberger, David C. (2022-05)
    The purpose of this project is to further advance Unmanned Aerial System flight capabilities with solar assisted flight. To reduce drag and increase flight efficiency, a flying wing configuration was selected and developed modeling the tradeoff between additional drag and power received from photovoltaic cells. To initiate the design process, strategies based on the needs were implemented to determine initial constraints. As the design methodology progressed, the selected parameters were finetuned and optimized to best meet the performance requirements and simplify the fabrication process. The chosen design was modeled for computational fluid dynamics simulations, stability and control analysis, and finite element analysis before manufacturing and physical testing. With the iterative design methodology, a final design was determined, and a prototype was developed testing the foam manufacturing processes and the overall design compatibility. Preliminary testing of the aircraft without photovoltaic cells as well as tests of the cells with the power system were performed to validate the power requirements and confirm the performance predictions.
  • Real-time lower limb monitoring system for physical therapy

    Russell, Shoa; Raskovic, Dejan; Thorsen, Denise; Mayer, Charles (2021-12)
    The Real-Time Lower Limb Monitoring System was created to show utility in measuring and displaying lower limb data in several formats and its use cases for both physical therapy and telehealth applications. This system consisted of pressure, orientation, and electromyography sensors. Initial sensor data processing is done on the microcontroller unit while additional processing, data storage, and real-time 3D visualization is done on the computer. With this system the users can gain a greater insight of the way their lower limbs work together when performing exercises and can track the progress and changes in their movements over time by saving the sensor data and reviewing the data using MATLAB. Overall, this system is a prototype for lower limb monitoring systems and could be expanded into many different areas of telehealth and lower limb monitoring. This project defense discusses the initial development and testing of the lower limb monitoring system and shows how the data can be displayed to the user, post processed, and discusses how the sensor data is being collected and assembled into a synergistic system.
  • Characterization of a novel dual-stator electric generator using finite element analysis

    Mozumder, Utpal Avro; Al-Badri, Maher; Wies, Richard; Huang, Daisy (2021-12)
    In a study published by the US National Renewable Energy Laboratory (NREL), it was shown that “Renewable energy sources, accessed with commercially available technologies, could adequately supply 80% of total U.S. electricity generation in 2050”. Therefore, a very rapid increase in renewable energy penetration in electric power systems is expected. The renewable energy harvesting process (except solar energy) involves technologies that utilize electric generators for energy conversion. Thus, the performance of generation units used in the renewable energy harvesting process is becoming more critical in electric power system stability, energy efficiency, and power cost. This project presents a characterization process performed on a novel dual stator permanent-magnet generator by using finite element analysis (FEM). The novel design is patented by the U.S. Patent and Trademark Office. The machine is built by using a state-of-the-art industryscale electromagnetic simulation tool available at the Department of Electrical and Computer Engineering at the University of Alaska Fairbanks. The patented design incorporates two types of generators; single-phase and three-phase types. This project is based on a three-phase design. The machine’s electrical and mechanical specifications which are detailed in the patent document were implemented, except the exciter design. It was decided to replace the proposed electromagnetic coils with permanent magnets. This selection was made to eliminate the copper loss in the field circuit (rotor) to maximize the machine’s efficiency. This also eliminated the use of slip rings and brushes which are considered a disadvantage due to the frequent maintenance requirement. However, it has the advantage of providing better control on the generated power at a wide range of speeds. NdFeB magnet is selected as it provides better flux density in low-speed operation. This was concluded via a comparison process conducted on magnet types available in the simulation tool. Based on the patented design, the generator was simulated with 12 rotor poles and 24 stator teeth. A reference speed of 600 rpm is used to ensure 60 Hz frequency operation. Due to the amount and type of steel used to build the apparatus, the machine demonstrates a quality reduction in the steel saturation under full-load operation especially at the critical parts of the machine (armature teeth). More importantly, the machine shows a high level of full-load efficiency. It is important to mention that this project is not a complete research work. Further characterization and optimization processes are still to be performed for the novel design to manifest its highest performance. This may be a research work to pursue in the future. This project was one step in this direction.
  • Performance evaluation and environmental partitioning of OP-40 chemical herder during herder mediated in situ burning of crude oil at varying environmental conditions

    Hasan, Md Ibnul; Aggarwal, Srijan; Schiewer, Silke; Perkins, Robert (2021-12)
    In situ burning (ISB) aided by chemical herders is one of the most suited and effective oil spill response (OSR) techniques for Arctic conditions. OP-40 has been reported as the most efficient and suitable herding agent among the two US EPA-approved herders; however, the fate of OP-40 in the environment after an effective ISB is not fully understood. Previous studies reported partial accumulation of OP-40 in water and confirmed the absence of OP-40 in the air after a burn. The only other possible place of OP-40 accumulation is burned oil residues; however, there was no standard method in previous peer-reviewed literature to quantify OP-40 in burned residues. Therefore, the first part of this study developed a novel OP-40 quantification method to quantify OP-40 in burned residues. The method used column chromatography followed by Gas Chromatography-Mass Spectrometry (GC/MS) analysis to quantify OP-40 in the residues. The method quantified more than 90% of the applied OP-40 from the burned residues. In the later part of the study, the efficiency of OP-40 herder at in situ burning and its fate in the environment after burning were parametrically investigated in bench-scale laboratory experiments with Alaska North Slope (ANS) crude oil. Experiments were conducted in three different water temperatures and two different water salinities to check OP-40's efficacy at the different environmental conditions and how those changes affect its fate in the environment. This study also investigated the effect of different herder volumes on the efficacy of OP-40 and the fate of OP-40 in the environment. The herding efficiency of OP-40 was excellent at all environmental conditions and for all three herder volumes. OP-40 showed higher herding efficiency in cold and low saline water, while burn efficiency was higher in cold water. This study recorded a maximum of 99.5% burn efficiency, with a minimum of 8.1%. On the other hand, the environmental partitioning study recovered a maximum of 99.7% of the applied OP-40 from the collected samples. An average of 34.4% and 24.1% of herder was found in water and residues, respectively. A higher percentage of applied OP-40 was found in burned residues at cold temperature and saline water.
  • Measuring fuel consumption as a proxy for heat loads in rural Alaska

    Vilagi, Alana; Huang, Daisy; Peterson, Rorik; Kim, Sunwoo (2021-08)
    Researchers with the Alaska Center for Energy and Power have developed a prototype of a non-invasive tool, the Pump Monitoring Apparatus (PuMA), to monitor the heating fuel consumption of a fuel oil vented heater. The goal of this project is to test the PuMA and develop it into a marketable tool for residential heat load research. As a majority of Alaskans rely on fuel oil to heat their homes, monitoring fuel usage is useful for two reasons. First, if the fuel oil vented heater is the only source of heat in the home, fuel oil consumption can be used as a proxy for residential heat load and thermal characteristics of the home can be deduced. Secondly, knowing heating fuel usage daily and seasonally can help inform researchers and consumers how human behavior and different home efficiency measures affect heat demand. There is currently a lack of a historical record of heating fuel consumption, limited understanding of home heating patterns on a daily, monthly and annual basis, and incomplete documentation of community heat loads. PuMA accuracy in calculating total heating fuel consumption was evaluated to range 3-10% from the actual value during testing. Several deployments of the PuMA have demonstrated its capability to remotely capture and report heating fuel consumption data, but have also highlighted technical challenges that will need to be addressed in future iterations of this tool.
  • Development of sulfidogenic bioremediation technology for the treatment of acid mine drainage in Alaska

    Yang, Qifan; Aggarwal, Srijan; Dev, Subhabrata; Schiewer, Silke (2023-08)
    When it comes to the treatment of acid mine drainage (AMD), sulfate-reducing bioreactors are more sustainable and inexpensive compared to traditional alkaline treatment methods. As a passive system, sulfate-reducing bioreactors require not only less energy, but also less labor for operation. Sulfate reducing microbial community present in the bioreactor utilizes 𝑆𝑂42− as electron acceptor and supplemented organic matter, such as glycerol, as terminal electron donor, and generates alkalinity and sulfides. This process not only neutralizes the acidity, but also removes soluble sulfate. The sulfides can further react with dissolved metal ions in the wastewater and produce precipitates. In this research, pilot scale column bioreactors were operated for 508 days at low pH and temperature conditions while being fed with AMD feed solution containing dissolved metals. The operating temperature varied between 5°C to 15°C to simulate the water temperature from early spring to later fall in Alaska. Our results showed that sulfidogenesis conditions in the bioreactors were able to help achieve complete removal of soluble zinc in all operating conditions, along with high removal of soluble iron and manganese.
  • High voltage power supply for a small plasma spectrometer

    Luebke-Laroque, Quetzal; Thorsen, Denise; Hampton, Donald; Wies, Richard (2023-08)
    This thesis describes the design, manufacturing, and testing of a high voltage power supply for an electron spectrometer to be used on a small spacecraft. The challenge was reducing complexity, size, and power consumption enough to be useful for a CubeSat or a sounding rocket sub-payload. The power supply has two purposes: i) it produces DC at roughly 2000 V for a microchannel plate detector and ii) it produces exponential voltage sweeps from about +4000 V to below 5 V for an electrostatic analyzer. This power supply uses solid state relays for a charge pump and for producing voltage sweeps with capacitive discharge. The detector power supply is software and hardware regulated to provide tunable output up to 2400 V, with voltage drift and ripple of around ±1%. The power supply is managed by an MSP430 microcontroller. It includes several automatic, hardware-based, closed-loop controls to stabilize performance across a range of temperatures, input voltages, and component parameters. All digital switching, signal changes, measurements, and monitoring are done in a single control loop. The design includes thermal protection, current limiting, a hardware watchdog, transient voltage suppression, and hardware-based overvoltage protection. The circuits survived thermal vacuum testing, operating within specifications for several weeks during many cycles of -40 °C to +70°C. The supply operated a real spectrometer inside an electron beam chamber. The consistent voltage sweeps allowed the spectrometer to accurately distinguish electron beam energies. This power supply is a successful proof of concept for powering a microchannel plate detector and an electrostatic analyzer at over 4000 V using a single 64 mm diameter circuit board, consuming 0.5 W or less from a small spacecraft.
  • Geophysical investigation of permafrost conditions in a thermokarst-prone area in Fairbanks, Alaska

    Basiru, Abdallah; Kidanu, Shishay; Darrow, Margaret; Emond, Abraham (2023-08)
    Permafrost degradation is a significant environmental concern for cold regions, posing risks to communities and infrastructure. The warming of near-surface permafrost leads to diverse topographic variations in the Arctic and sub-Arctic communities. The varying rates of thawing permafrost, influenced by ground ice content, give rise to geologic hazards like thermokarst, which causes ground subsidence. This gradual or sudden subsidence endangers existing infrastructure and economic activities in cold regions. A subsurface 2D Electrical Resistivity Tomography survey was conducted in the West Ridge area of the University of Alaska Fairbanks upper campus to advance our understanding of frozen ground conditions. The objective was to monitor the ground thermal regime and permafrost conditions over a year and characterize permafrost conditions at a thermokarst-prone site. Various data filtering and processing techniques were employed for analysis, including the Depth of Investigation index, optimal smoothing parameters, and the utilization of two array types. Additionally, borehole data and the Very Low-Frequency Electromagnetic method were integrated to provide further insights into subsurface features and resistivity contrasts. This approach aimed to mitigate potential misinterpretation or overinterpretation of inversion results. By employing the 2D Electrical Resistivity Tomography method, we gained valuable information on the spatial variability of transient processes, such as the movement of freezing and thawing fronts. Analysis of the time-lapse data revealed a pronounced increase in resistivity within the active layer during the winter, followed by a decrease during summer. Resistivity profiles across the site prone to thermokarst depression exhibited distinct variations in permafrost conditions, with both low and high resistive anomalies observed along the transects. These anomalies, representing taliks and ice wedges, were characterized by resistivity values below 50 Ωm and above 700 Ωm, respectively. The Very Low-Frequency Electromagnetic method results demonstrated similar resistivity trends, although the anomaly patterns differed from those observed in the ERT data. The outcomes of this study contribute to an improved understanding of permafrost, which is vital for engineering applications and infrastructure stability.
  • Improving the efficiency of a flooded-bed dust scrubber using a modified demister

    Asawa, Darshil; Arya, Sampurna; Ghosh, Tathagata; Fan, Long (2023-08)
    Dust generation is a significant issue in the U.S. mining industry, particularly the underground coal mining industry. It causes health and safety issues for the miners working underground. Prolonged exposure to high concentrations of respirable dust (dust of aerodynamic diameter < 10 μm) causes various diseases, including pneumoconiosis, also known as Black Lung, and silicosis. These diseases lead to an airflow blockage in the lungs, causing lung failure or death. Several techniques have been used to capture respirable dust particles, and a flooded-bed scrubber integrated into a continuous miner is one of them. This research focuses on increasing the efficiency of a flooded-bed scrubber by modifying the geometry of one of its components, known as a demister. A demister consists of a series of sinusoidal plates that separate water droplets from air and contribute to the capture efficiency and pressure drop across the scrubber. The geometry of the demister was modified by adding aerodynamic devices, called Vortex Generators (VG), on its plates. Several computational fluid dynamics (CFD) models of a modified demister were created, and CFD simulations were performed. An analysis of results indicated an improved water droplet capture efficiency for the modified demister. The study also discovered a potential to reduce the size of the demister which will reduce the pressure drop and eventually the energy consumption of the scrubber.
  • Experimental examination of corrosion preventative coating: titanium dioxide nanoparticle reinforced polystyrene nanocomposite

    Smith, Caleb Philippe; Zhang, Lei; Chen, Cheng-fu; Kim, Sunwoo (2022-02)
    The material revolution that so many engineers have longed for has at last reached public forethought. Nanomaterials, characterized by having at least one dimension in the size of one to hundreds of nanometers, have properties that differ from their bulk material properties. The number of materials that engineers have available for synthesis of designs has greatly increased in the last ten years, and they can now tailor the material with choices from the macro to the nanoscale, and everything in between. Conventional coatings, consisting of a binder and particles, can have improved properties by the inclusion of particles in the nanoscale regime. Ultraviolet resistance, corrosion inhibition, and toughness are just a few of the ways that nanomaterials can improve conventional materials. Disparate fields of mechanical engineering have already seen improvement due to nanomaterials, including heat transfer, lubricity, and mechanical strength; the field for applying nanomaterials is fast growing and cross discipline, nanoscale coatings are sure to have huge impacts on computing, aerospace design, pollution, and a myriad of other applications. This project was conducted to examine the effects of including anatase titanium dioxide nanoparticles into a polystyrene layer through capillary rise infiltration and the improvement of corrosion resistance compared to a conventional polymer coating.
  • Mitigation of ground control issues using artificial intelligence techniques

    Adebanjo, Temitope; Bandopadhyay, Sukumar; Arya, Sampurna; Ghosh, Tathagata (2023-08)
    Ground hazards are a major safety concern in underground mines, causing deaths, injuries, and lost work time to miners. Although ground hazards such as roof fall accidents have steadily and significantly declined over the last decade, the safety hazards associated with ground hazards still account for a significant portion of the total number of accidents in the underground mining industry. One of the main reasons behind ground hazards in underground mines is abrupt changes in geological conditions that may decrease the competence of the rocks surrounding an excavation, resulting in ground failure. The changes in geological can be detected in a mined-out area, and a possible roof fall accident can be avoided if prompt countermeasures are taken, but changes cannot be easily foreseen in unexcavated areas. An obvious solution to this issue would be to predict strata geological conditions in advance of mining, followed by risk assessment and design of a safe and cost-effective ground support system. The prediction of geological conditions plays a vital role in mine planning and design. It is significantly important for the mine workers' safety and could be economically attractive in terms of increased productivity and reduced production loss. However, predicting changes in geological conditions in unexcavated areas is a complex task, and it requires proper mine strata characterization and mine design. This research aims to address ground control issues in the mining industry by utilizing Artificial intelligence (AI) techniques to predict lithology and RQD based on the location input data ( x, y, and z coordinates). The accurate prediction of lithology and RQD is crucial for effective ground control management in mining operations. The methodology developed in this research involves the creation of a predictive model using various machine learning algorithms. The input dataset is comprised of drill hole x, y, and z coordinates, and the outputs are lithology and the RQD. The model was trained, optimized, and validated using a large set of drill hole data from an underground metal mine. The results show that the random forest (RF) model performed better than other models, with a prediction accuracy of 98%. The trained model was used to build an interactive-user interface. By inputing just any location x,y, and z coordinates within the mine, into the interface, authorized users can get output of lithology and RQD for that location. This research may help improve the accuracy and the efficiency of ground control management practices in the mining industry, as well as economically benefit the industry.
  • A Low-cost alternative to mitigate heavy metal and phosphorous contamination in water

    Blood, Brittany; Misra, Debasmita; Aggarwal, Srijan; Metz, Paul; Duffy, Larry; Dev, Subhabrata (2021-03)
    Heavy metals and phosphorous are contaminants that may enter surface waters through mining and agricultural activities. As these activities occur in Alaska, it is important to analyze locally available biosorption materials that may be available in Alaska and may reduce costs to current treatment methods. The adsorption of lead (Pb), cadmium (Cd), and phosphorous (P), by sodium hydroxide-treated, Alaskasourced spruce sawdust at 6.5°C, 15°C and 22.5°C was analyzed. Three kinetic models (zero-order, pseudo first-order, and pseudo second-order) were used to analyze the adsorption kinetics and mechanism. The pseudo second-order kinetic model best described the adsorption of Pb, Cd, and P at all three temperatures, and the adsorption mechanism was determined to be driven by chemisorption. Optimal contact time for adsorption was determined for all three temperatures. At 22.5OC, adsorption equilibrium was reached at 3 hr, 1 hr, and 1.5 hr for Pb, Cd, and P, respectively. Adsorption equilibrium at 15OC was reached at 9 hr, 7 hr, and 9 hr for Pb, Cd, and P, respectively. At the lowest temperature, 6.5 OC, adsorption equilibrium was reached at 11 hr, 14 hr, and 12 hr for Pb, Cd, and P, respectively. Adsorption behavior was further evaluated by fitting the Langmuir and Freundlich isotherm models to the adsorption isotherm data. The adsorption behavior of Pb, Cd, and P were found to vary greatly from each other at each analyzed temperature. Pb adsorption favored the Langmuir isotherm, while Cd and P favored the Freundlich isotherm. Further, adsorption of Cd was found to be unfavorable to the spruce sawdust adsorbent. Apart from elucidating the adsorption properties ofspruce sawdust for locally relevant contaminants, the adsorption data trends in this work suggested that the temperature effects on the adsorption of Pb, Cd, and P vary. The effects of decreasing temperature are not equal for the adsorption of these different sorbates, indicating adsorption limitations at decreased temperatures, that may vary with respect to sorbates analyzed in adsorption studies.
  • Development of a sulfolane plume in an aquifer located in discontinuous permafrost

    Whiting, Catherine E.; Barnes, David; Aggarwal, Srijan; Shur, Yuri (2023-05)
    The release of sulfolane from a petroleum refinery to a river flood plain aquifer in a discontinuous permafrost region in North Pole, Alaska has been thoroughly monitored, with the initial site characterizations beginning in 2009. It has been observed that the sulfolane plume advancement is different from typical contaminant plume development in aquifers in the temperate region. This difference relates to the existence of permafrost. Permafrost itself is impermeable but open or lateral taliks provide a connection point of subpermafrost and suprapermafrost groundwater. The redirection of groundwater by these thawed areas in permafrost can produce unpredictable contaminant concentrations at various depths of the aquifers. Groundwater also has the ability to converge and diverge as a result of varying permafrost-table distribution. The contaminant can be channeled and redirected in an area with a deep permafrost-table and be absent or minimal along a shallow permafrost-table. The objective of this study is to examine the relationship between the progression of the sulfolane groundwater plume and the spatial distribution of the discontinuous permafrost and topography in the area between the Tanana and Chena Rivers using the results obtained from 156 monitoring wells, including well logs and sulfolane concentrations. An additional goal of this research is to classify the permafrost features and mechanisms controlling the transport of sulfolane. Spatial maps of the temporal contaminant distribution are produced to aid with the plume delineation, as well as contaminant trend analyses for each monitoring well (shallow/mid/deep) sulfolane concentration over the measured period. A permafrost-table elevation (top of permafrost) map was developed and utilized as a base map under the sulfolane concentration contours to correlate permafrost location and the spatial distribution of sulfolane over a period of six years. This study finds that the variable distribution of permafrost has a great effect on the flow of groundwater, and thus contamination, in the aquifer. The presence of open taliks is the most substantial modifier to the predicted path of the sulfolane groundwater contamination plume. In addition, degradation of permafrost distribution in the future due to thawing would further enhance the preferential movement of the groundwater and sulfolane and continue to move contamination in directions that would not have been predicted by looking at regional groundwater gradients alone. An area thought to be absent of sulfolane contamination may become susceptible, and the well network should be expanded to accommodate extended monitoring of this particular sulfolane plume.
  • Investigating factors affecting energy consumption in rural Alaskan water treatment and distribution systems, and exploring energy-saving strategies for wastewater treatment in cold climates

    Rashedin, Muradur; Aggarwal, Srijan; Dev, Subhabrata; Schiewer, Silke; Huang, Daisy (2023-05)
    Underlying permafrost in rural and remote Alaskan communities creates difficulties in connecting these communities to the electrical grid, resulting in the import of fuel from nearby cities by air or barge for electricity generation. During the winter months, a large amount of fuel and electricity is required for water treatment and distribution in these communities to keep the water temperature above freezing. Furthermore, domestic wastewater in rural Alaska is treated within wastewater lagoons, which lose their treatment efficiency during the freezing winter months. In contrast, the biological aerated filter (BAF), which has become an efficient alternative for domestic wastewater treatment in off-grid houses, consumes higher energy in the form of continuous aeration. As a result, residents living in rural Alaska pay significantly higher utility costs compared to the national average. This study is designed with two goals, to determine the factors contributing to higher energy consumption for water treatment and distribution and to evaluate energy consumption and BAF performance for wastewater treatment at different aeration regimes. The overall study is based on the following two hypotheses: (i) factors including seasonal changes, geographical regions, population size, and water distribution system (WDS) types influence energy consumption for water treatment and distribution, and (ii) intermittent aeration saves energy without impacting BAF performance for wastewater treatment. After analyzing energy audit data from the Alaska Native Tribal Health Consortium (ANTHC) for 78 rural Alaskan communities, we found that average per capita energy consumption was highest in interior Alaska (1826 kWh), followed by Northern (917 kWh), Southwestern (660 kWh), Gulf Coast (492 kWh), and Southeastern (136 kWh) regions. Among the water distribution system (WDS) types, piped circulating systems showed the highest energy consumption (1100 kWh), followed by washeteria (1000 kWh), closed hauling (800 kWh), individual wells (550 kWh), and piped pressure (300 kWh) systems. In the BAF experiment, we operated a bench-scale BAF at continuous and intermittent aeration regimes (1 hour on/1 hour off, and 2 hours on/2 hours off) using synthetic wastewater and evaluated the treatment efficiency in terms of chemical oxygen demand (COD) removal. The results showed similar COD removal rates for continuous aeration (67.6%), 1 hour on/1 hour off (66.5%), and 2 hours on/2 hours off (63.4%) aeration regimes. Additionally, we found that intermittent aeration regimes consumed significantly less energy than continuous aeration. This research helps to understand energy consumption for water treatment and distribution in rural Alaskan communities and provides a potential energy-saving approach for treating wastewater in Arctic communities.
  • Comparison of Arctic Alaska historical snow data with satellite-derived benchmarks and model results using ILAMB software

    Szatkowski, Mary; Bolton, W. Robert; Stuefer, Svetlana; Bennett, Katrina (2022-12)
    Understanding and modeling the permafrost system, hydrologic cycle, energy balance, and biologic systems in the Arctic are dependent, in part, on snow depth and snow distribution. Point-source snow measurements provide ground-truth observations of snow depth and snow water equivalent, although these measurements may be limited in their spatial and temporal distributions. Satellite-derived remote sensing products and gridded model output provide spatial coverage of snow properties, but their applicability is affected by their balance of resolution, computational speed, and accuracy confidence. The goal of this research is to assess the performance of three snow data products derived from remote sensing techniques as well as model output across the North Slope of Alaska with the International Land Model Benchmarking (ILAMB) Project software. Historic ground-based snow data, collected by agencies, academia, and industry, and dating from 1902 to 2021, was curated to create an ILAMB-compatible benchmark dataset for end-of-winter (EOW) snow depth and snow water equivalent (SWE) for the evaluation of the three snow data products: Canadian Sea Ice and Snow Evolution (CanSISE) network SWE; Arctic Boreal Vulnerability Experiment (ABoVE) snow depth; and Energy Exascale Earth System Model (E3SM) Earth Land Model (ELM) snow depth. The ILAMB evaluation results showed that the ABoVE data product is effective in providing the average EOW snow depth for regions of the North Slope but lacks representation of interannual and spatial variability of snow depth. Comparatively, the CanSISE data product and ELM results are inaccurate in magnitude for applicability across the North Slope of Alaska in addition to lacking representation of snow condition spatial variability. In interpreting ILAMB results, factors to consider were representation bias from inconsistent benchmark site distribution throughout the evaluated time period, the range of dates considered to represent the spring snow data, and uncertainty within the individual benchmark values. Future analysis of the same datasets with ILAMB could include diagnostic tests to understand the sources of error better. Thorough spring snow data collection should continue on the North Slope of Alaska to inform and improve Earth System Models.
  • Development of an active vacuum insulation panel for use in building applications

    Nelson, Haley D.; Marsik, Tom; Peterson, Rorik; Huang, Daisy (2022-12)
    Vacuum insulation panels, or VIPs, are among the highest performing forms of building insulation available on the commercial market, with some per inch R-values advertised as 60°F·ft²·hr/(BTU·inch). Though there is strong market demand for high-performing forms of insulation, the adoption of VIPs is hindered by their relatively high costs, uncertain service lifespans, sensitivity to internal pressure changes, susceptibility to thermal bridging along their edges, and other issues. Particularly in building applications, typical VIPs are often passed over in favor of insulation types that can be easily customized on-site, are produced to larger dimensions, and are not as vulnerable to damage or rough handling. Many of these challenges can be addressed by VIPs equipped with the means to be evacuated as often as is necessary to reestablish a desired internal pressure, termed "active VIPs." The primary aim of this research was to develop and assess the thermal performance of an active VIP prototype. A system assembly for testing active VIP prototypes was first developed, and its testing capabilities assessed. Following confirmation of its testing efficacy, an active VIP prototype was constructed using a metallized barrier laminate and fiberglass core insulation, and its performance profiled in terms of its thermal conductivity as a function of the internal pressure. The active VIP prototype was found to have an R-value per inch of about 38°F·ft²·hr/(BTU·inch) at internal pressures on the scale of 10⁰ mTorr. This R-value per inch is about an order of magnitude higher than conventional types of insulation used in building applications. From results obtained, the active VIP prototype may be considered a viable candidate for further research and development.
  • A design and implementation of a low-power embedded system for data collection in an airborne sea ice thickness observing system

    Asurapmudalige, Thimira Sanuka Thilakarathna; Raskovic, Dejan; Hatfield, Micheal; Thorsen, Denise (2022-12)
    The Long-Range Airborne Snow and Sea Ice Thickness Observing System (LASSITOS) is an airborne electromagnetic (AEM) system, currently under development, which uses a customdesigned instrument mounted on an Unmanned Aerial System (UAS) to measure Arctic sea ice and snow thickness. This project requires specialized instruments that are both low-power and lightweight. This thesis describes a design and implementation of a prototype data logging system based on an ultra-low power microcontroller, for the LASSITOS instrument. Three 32-bit Analog-toDigital Converter (ADC) integrated circuits (IC) are used to sample and convert the receiving EM signal at a rate of 19200 SPS. The system is capable of writing the sampled data and diagnostic data to the SD card at a combined rate of up to 307200 B/s. A 30 KB circular buffer is used to avoid data loss during SD card busy periods. Three DMA channels are used to optimize the communication between the ADCs and the SD card over SPI to achieve these data rates.
  • Investigating impact of pulp density on flotation performance

    Dehghani, Fahimeh; Ghosh, Tathagata; Aggarwal, Srijan; Chen, Gang; Arya, Sampurna (2022-08)
    The Red Dog Mine, located in northwest Alaska, is one of the world's largest zinc/lead mines. The processing mill feed consists of a blend of ores from two different pits, namely, the Aqqaluk pit and the Qanaiyaq pit respectively. The mill circuit consists of grinding and multiple flotation circuits which separate zinc and lead minerals from their gangue contents depending on the interfacial tension between hydrophilic/hydrophobic mineral surfaces and their environment. The flotation circuit feed is characterized by high percent solids (~ 50%). Percent solids can potentially have a significant effect on the grade/recovery curve. Thus, it is very common that low-density slurries give better flotation response (high grades), particularly in flotation systems containing a significant amount of liberated hydrophilic unwanted mineral particles. Moreover, the blended feed is metallurgically complex and weathered, thus adversely affecting the performance of the mill. This project investigated the effects of pulp density on Red Dog flotation circuit performance and develop strategies to maximize recovery at 50% solids. Higher solids content increases the rheology of the slurry thereby causing turbulence and froth instability. To study the impacts of slurry density on flotation kinetics, a series of experiments were conducted by varying various operating and process parameters and assessing circuit optimization strategies. Initial batch tests performed on cyclone overflow samples showed that residence time, rotor revolution per minutes (RPM), and slurry density are important factors affecting flotation performance. Lower slurry densities usually lead to better kinetics. However, in the case of the initial tests, results indicated that slurry density has a minimal effect if residence time is increased. It was shown that yields as high as 73% with Lead (Pb) recovery values of 86.20% is possible even at 60% solids concentration by increasing the residence time. If the slurry is sufficiently diluted then higher rotor speeds combined with higher residence time would provide higher yields and recoveries. Initial results indicate that at lower RPM ranges, adequate residence time and higher slurry densities lead to better bubble loading and froth stability. Lead (Pb) and Zinc (Zn) recovery values of 89.42% and 80.33% were achieved at 20% solids and 1800 RPM rotor speed. Future test work includes investigation of froth stability and pulp phase kinetics, statistically, and designed programs to optimize flotation performance in high-density slurries. Several parameters including dosage, and type of collector, pH, the dosage of frother, dosage of depressant, the dosage of activator, type of grinding media, particle size, and bubble size were controlled in the optimization tests. The optimized condition was obtained for both galena, and sphalerite at different solid%. The locked cycle tests were designed based on the Red Dog flotation circuit. At the optimized condition, the grade, and recovery for solid 30% improved by around 0.5%. The optimized condition had a further impact on the flotation performance at a higher solid%. By increasing the solid%, the grade was improved by 1.84%, and 2.24% at galena concentrate for 40%, and 50%, respectively, compared to the normal condition. Recovery was improved for both solid% by less than 1%. The optimized condition increased Zn grade at the flotation circuit by 1%, and recovery by 4% for 40% of solid. In addition, the optimized condition increased grade at the flotation circuit by 5%, and recovery by 4% for 50% of solid.

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