Recent Submissions

  • Controlling dust concentration in a fan housing using settling chambers and water sprays

    Quevedo Delgado, Cristian Alonso; Arya, Sampurna N.; Ghosh, Tathagata; Fan, Long (2023-12)
    Dust generation is a consequence of various activities in the mining industry. The industry generates dust in quantities that can present occupational health hazard and equipment damage. A notable instance of equipment deterioration is the corrosion and erosion experienced by fan blades in underground mines. This thesis introduces settling chambers and water spray as feasible techniques commonly used for controlling dust in underground mine operations. The research aims to provide a low capital cost and maintenance-free system to capture the dust particles upwind of the main fan. The research focuses on an underground polymetallic mine in Peru, serving as a case study. It was conducted in two distinct phases. In the first phase, airflow data in the upcast shaft and the fan housing was collected from the collaborating mine in Peru. Subsequently, a 3D model of the shaft and the fan housing system was developed, and a Computational Fluid Dynamics (CFD) simulation of the airflow in the system was performed. The results of the CFD simulation were compared against the airflow data from the mine, and the CFD model was validated. The 3D model of the upcast shaft-fan housing system was adapted to incorporate the settling chamber, which underwent variations in shape, length, and hydraulic diameter, resulting in the creation of 18 modified models. For each model, CFD simulation was conducted in steady-state condition to establish flow in the computational domain, followed by transient-state simulations to replicate the behavior of dust and assess the settling chamber's efficiency in capturing dust particles with aerodynamic diameter ranging from 1 μm to 400 μm. Furthermore, Sensitivity analysis was performed to examine the effect of shape, length, hydraulic diameter, and airflow velocity on the capture efficiency of the settling chamber. Analysis of the simulation results indicated a significant dust reduction of up to 60%. The second phase of the research involved simulated the capture of dust using water spray system within a return entry. Different water spray nozzles, characterized by varying spray angles, velocities, and droplet sizes, were simulated to evaluate their impact on dust capture efficiency. The analysis of the results revealed that the system could achieve a dust capture efficiency of up to 60%.
  • Marine methane: sources and potential adverse effects

    Mahmuda, Sadia; Aggarwal, Srijan; Rea, Lorrie; Dev, Subhabrata (2023-12)
    Recently, there has been an increase in the occurrence of incidents involving spills of oil and natural gas, such as methane. The world experiences at least one major spill in each decade. An illustrative case is the Deepwater Horizon oil disaster in 2010 in the Gulf of Mexico. This catastrophe resulted in the discharge of about 205.8 million gallons of oil and 225,000 metric tons of methane gas into the Gulf of Mexico. More recently, in 2022, the Nord Stream pipeline leak occurred, which was the largest single methane release ever recorded. It released up to 500K tons of methane underwater, a greenhouse gas with a significantly higher potency than carbon dioxide. Due to the Deepwater Horizon incident, mammals, sea turtles, birds, fish, and invertebrates were adversely affected and caused damage to the corals. More than 90 bird species died, and 1300 miles of shoreline became polluted. The fishing industry suffered a significant reduction. This study systematically reviewed the source and impact of methane in the marine environment, utilizing 271 peer-reviewed academic publications, eight non-peer-reviewed sources, and 44 online resources. In the marine environment, methane can come from various sources such as methane hydrate, methane seeps, pockmarks, mud volcanoes, microbial activities, and anthropogenic sources or human-induced activities. Sediment typically contains methane from methane seeps, methane hydrates, mud volcanoes, and microbial activity. In the water column, methane is produced from diffusion from hydrates, seeps, hydrothermal vents, and thermogenic and anthropogenic sources. On the other hand, air-water interface methane comes from the atmospheric exchange or diffusion from the water column or sediment. In marine water, methane undergoes various reactions. Methane reacts with oxygen, producing carbon dioxide in aerobic conditions. Conversely, in anaerobic conditions, methane is anaerobically oxidized, coupling with sulfate reduction mediating by sulfate-reducing bacteria and methanotrophic archaea. These microorganisms, bacteria, and archaea derive the majority of their carbon and energy from methane, and they can proliferate their number where they find excess methane. However, excess methane can create anoxic conditions by reducing oxygen concentration. Invertebrates utilize methane through a symbiotic relationship with methane-consuming microorganisms. Moreover, the marine ecosystem exhibits complex interdependencies among the organisms and methane.
  • Biorecovery of rare earth elements from hard rock, extraction and analysis

    Kebe, Moustapha; Ghosh, Tathagata; Briggs, Brandon R.; Aggarwal, Srijan (2023-12)
    The advancement toward green energy, the development of precise weaponry, and the conquest of space have made the consumption of rare earth elements and critical elements supersede their production. Rare earth elements are vital and critical for modern technology. Rare earth elements consist of Scandium, Yttrium, and the fifteen elements in the Lanthanide group. These elements are mainly categorized into two types based on their atomic number: Light Rare Earth Elements (LREE) and Heavy Rare Earth Elements (HREE). The conventional methods of extracting economic rare earth elements are widely known, and these methods are found in abundance. However, considering the critical nature of rare earth elements, and the challenge to avoid environmental degradation, finding an alternate method of extracting rare earth elements that is both economically and eco-friendly is needed to overcome the disruption in demand and supply of these elements. One of the many potential methods of rare earth elements extraction is bioleaching or bio-recovery using bacteria, fungi, and archaea. This method has drawn the attention of several researchers in the quest for sustainable and feasible extraction techniques of rare earth elements and other critical elements (CEs). Bio-recovery or bioleaching as compared to physicochemical methods is considered one of the most promising techniques for recovering critical elements. A specific type of bacterial strain the Shewanella oneidensis MR-1 was incubated with rock samples from two distinct locations (North Pole Hills and the Prince of Wales Island) to recover rare earth elements. The experiment was performed under standardized conditions to ensure the reliability of the results. Three major parameters such as the process duration, particle size, and incubation period were tested to evaluate their impact on the recovery process. A total recovery of 30.85 ppb and 7.6 ppb at North Pole Hills and Prince of Wales Island, respectively. The process duration parameter was found to be irrelevant throughout the experiment and the effect of particle sizes ranging below 150 Mesh shows a positive response to the bio-recovery processes compared to particle sizes ranging between +-0.5mm. Maximum recovery was recorded with the samples from North Pole Hills compared to the samples from the Prince of Wales Island. The Bioleaching process was compared with the traditional acid leaching process, and a total of 291.73 ppb was recovered from the North Pole Hills and 107.75 ppb at the Prince of Wales Island. This experiment sets a road map to understand the microbial interaction on hard rock with varying sample sizes and process time.
  • Icy insights: decrypting the depths with novel stochastic techniques to model and mitigate Arctic under-ice oil spills

    Frazier, Kelsey A.; Peterson, Rorik; Kasper, Jeremy; Walsh, John Jr.; Webster, Melinda (2023-12)
    The retreat and thinning of Arctic sea ice, driven by climate change, have increased the potential for maritime navigation in the region, thereby heightening concerns about the environmental impacts of potential oil spills in the Arctic. This dissertation, with a focus on the Beaufort and Chukchi Seas, seeks to develop a remote predictive method for assessing the subsurface features of Arctic sea ice, thereby facilitating rapid responses to Arctic oil spills without depending on time-consuming in situ measurements. The first paper of this dissertation addresses the need for oil spill modelers to understand oil movement along the subsurface of sea ice. Employing sonar data from the Chukchi Sea, the study investigates whether the subsurface topography of sea ice exhibits fractal scaling behavior. It was found that young sea ice exhibits multifractal scaling geometry, with parameters α, c1, and H determined as 1.2, 0.03, and 0.12, respectively. Fractal scaling behavior was not observed in other types of sea ice, highlighting the need for further research in this area. These findings are instrumental in enhancing predictive models for oil slick migration under sea ice, a crucial aspect of Arctic oil spill preparedness and mitigation. The dissertation's second paper analyzed five years of field data to determine the statistical distributions of subsurface features beneath various ice stages, using indirect assessment techniques. The analysis revealed that, with few exceptions, the subsurface features of sea ice predominantly follow lognormal distribution patterns, each characterized by distinct mean (mu) and standard deviation (sigma) values. This research represents a significant step forward in remote sea-ice characterization and is vital for formulating effective oil spill responses in the Arctic. The final paper utilized Arctic sea ice stage data, interpreted from satellite imagery, and sea ice draft data from moored sensors in the Beaufort and Chukchi Seas. This data was pivotal in accurately modeling the under-ice morphology, essential for establishing boundary conditions for realistic gravity-driven flow simulations. The study found that potential oil sequestration volumes could range from 30,000 to 1 million cubic meters per square kilometer, varying with the ice stage conditions. Additionally, the models suggest that under-ice morphology significantly influences oil slick movement, with only 20-40% of the ice surface encountering oil. This complexity highlights the intricate nature of Arctic oil spill cleanup and the potential for oil encapsulated in sea ice to cross international boundaries, emphasizing the need for comprehensive preparedness and international cooperation in Arctic oil spill response strategies.
  • Laboratory and field testing of the Knudsen bowl concentrator

    Mark Anthony, Michael Richard; Johansen, Nils I.; Walsh, Daniel E.; Bandopadhyay, Sukumar (1995-08)
    During 1985 and 1986 both laboratory and field test work were conducted to study the operating parameters of the Knudsen bowl concentrator. In the past, some miners have attempted to use these bowls in Alaska, but have not been able to operate them profitably, because of the lack of accurate operating information. This study carefully examined different operating parameters of the Knudsen bowl and their effect on bowl capacity and recovery of gold. The results of the laboratory study were field tested at EVECO’s placer gold operation near Fox, Alaska. The testing showed that for a continuous feed operation the recovery of 48x65 mesh gold decreases when the feed size is over 1/8 inch or the feed rate is over 2 cubic yards per hour. The Knudsen bowl's operating characteristics would make it a logical choice as a secondary concentrator.
  • 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.

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