Browsing by Author "Bareither, Christopher, committee member"
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Item Open Access Development of a Martian in-situ hybrid rocket motor(Colorado State University. Libraries, 2020) Babazadeh, Iman Andrew, author; Marchese, Anthony, advisor; Mizia, John, advisor; Bareither, Christopher, committee memberOne of the chief obstacles that has prevented a human mission to Mars is the excessive amount of mass that must be launched into low earth orbit to assemble the Mars-bound spacecraft. Since propellants alone account for 75% of the total mass requirements, a new concept has been proposed for both manned missions and unmanned robotic sample return missions, which relies on In-Situ Resource Utilization wherein propellants for the return trip to Earth are manufactured from raw materials available on Mars. This research focused on the development and testing of a unique propulsion system that could enable in-situ use of the Martian atmosphere as an oxidizer source and Martian soil as a fuel source for the return journey back to Earth for manned and unmanned vehicles. The propulsion system employs carbon dioxide as an oxidizer and metals as the fuel component. The need to understand and test this concept is significant as there is currently little experimental knowledge on the performance of carbon dioxide oxidizer and metallic fuels in rocket engines. Aluminum and magnesium fuels are the leading choice for burning with carbon dioxide as they can liberate the contained oxygen for rapid combustion to occur. Magnesium is favorable for its ignitability characteristics, whereas aluminum has a higher energy density but is more difficult to ignite due to the formation of its oxide layer. In the research conducted for this thesis, aluminum and magnesium particles were both considered to determine an optimal system that could be used to model an actual Mars propulsion system. The project entailed a myriad of combustion tests based on a conventional hybrid rocket motor in which the metallic fuel particles were encased in a polymer matrix binder and oxidized through a liquid oxidizer. The hybrid rocket motor configuration is not only amenable for the Mars environment because of ease of storage, but also afforded great adaptability safety for the experimental studies described here because of the simplicity of refueling procedures and because the fuel component itself aids in keeping the combustion chamber wall cool, thereby eliminating the need for an active cooling system. Through initial testing, it was observed that adding an additional oxidizer aided in the combustion of carbon dioxide with high percentage metal fuel grains. Specifically, the results of this study suggest that using nitrous oxide as a complementary oxidizer was beneficial in attaining sustained combustion. However, it was also found that miscibility and mixing issues between the carbon dioxide and nitrous oxide oxidizers led to induced combustion instability during the hybrid test fires that had a 50% carbon dioxide and 50% nitrous oxide mixture ratio.Item Open Access Development of advanced microbial communities for enhancing waste hydrolysis processes: insights from the application of molecular biology tools(Colorado State University. Libraries, 2016) Wilson, Laura Paige, author; De Long, Susan K., advisor; Sharvelle, Sybil, committee member; Bareither, Christopher, committee member; Weir, Tiffany, committee memberAnaerobic digestion (AD) is an environmentally attractive technology for conversion of various solid wastes to energy. However, despite numerous benefits, AD applications to OFMSW remain limited in North America due to economic barriers with existing technologies. Suboptimal conditions in anaerobic digesters (e.g., presence of common inhibitors ammonia and salinity) limit waste hydrolysis in AD and lead to unstable performance and process failures compromising economic viability. To guide development of microbial management strategies to avoid process upsets and failures due to inhibitors, hydrolysis rates were determined in batch, single-stage digesters seeded with unacclimated or acclimated inocula under a range of ammonia and salinity concentrations for two model feedstocks (food waste and manure). Using unacclimated inocula, hydrolysis was found to be severely inhibited for elevated ammonia (decrease of nearly 4-fold relative to baseline) and salinity (decrease of up to 10-fold relative to baseline). However, for inocula acclimated over 2 to 4 months, statistically significant inhibition was not detectable except in the case of food waste subjected to elevated ammonia concentrations (p-value = 0.01). Inhibitors and feedstock were found to have a major influence on bacterial community structure. Next, a more detailed analysis of the acclimation process revealed that microbial communities under stressed conditions (elevated ammonia) adapt more slowly (weeks) to feedstock changes (from wastewater sludge to manure or filter paper) than under non-stressed conditions (days). Molecular tools were utilized to separate temporal effects on hydrolyzers from temporal effects on methanogens. Bacterial and archaeal sequencing results identified multiple organisms (e.g., Clostridiales vadinBB60, Ruminococcaceae, Marinilabiaceae, Methanobacterium, and Thermoplasmatales Incertae Sedis) that were selected for in microbial communities in stressed reactors under perturbed conditions (feedstock changes). Collectively, results from these studies suggested that weeks of acclimation are required to build up sufficient quantities of desired hydrolyzing microbes; thus, hydrolysis processes operated in batch mode should be inoculated with each new batch, and desired microorganisms should be maintained in the system via properly developed inoculation strategies. To identify improved methods of maintaining such communities in multi-stage reactor systems, reactor performance under elevated ammonia and salinity was compared for leach bed reactors (LBRs) seeded with unacclimated inoculum and different ratios of acclimated inoculum (0-60% by mass) at start-up. Additionally, the effect of seeding methods was examined by identifying the optimal ratio of fresh waste to previously digested waste in multi-stage systems incorporating leachate recycle during long-term operation. Results demonstrated that high quantities of inoculum (~60%) increase waste hydrolysis and are beneficial at start-up or when inhibitors are increasing. After start-up (~112 days) with high inoculum quantities, leachate recirculation leads to accumulation of inhibitor-tolerant hydrolyzing bacteria in leachate. During long-term operation, low inoculum quantities (~10%) effectively increase waste hydrolysis relative to without solids-derived inoculum. Additionally, molecular analyses indicated that combining digested solids with leachate-based inoculum doubles quantities of Bacteria contacting waste over a batch and supplies additional desirable phylotypes Bacteriodes and Clostridia. To provide detailed insight into microbial community activity during degradation, metatranscriptomic analyses were conducted on reactors fed food waste and manure under low ammonia, and several common active (e.g., Methanomicrobia, Methanosaeta concilii, and Clostridia) and unique active (e.g., Enterobacteriaceae, Clostridium thermocellum, and Clostridium celluloyticum) phylotypes between the reactors were identified. Functional classification of the active microbial communities generally revealed several similarities between the reactors despite the differences in feedstock. However, similarities or differences in transcript abundance for specific gene categories (e.g. one-carbon metabolism or fermentation) might indicate some potentially useful biomarkers for monitoring process health. Additionally, data from this experiment expanded the gene sequence database for assay development, which is particularly key for improving current functional gene-targeted assays to more accurately characterize microbial communities. Overall, results from this study have provided operational guidance for establishing and maintaining desired microbial communities as inocula to enhance waste hydrolysis for a variety of feedstocks.Item Open Access Disruptive packing of binary mixtures(Colorado State University. Libraries, 2016) Zou, Shuai, author; Heyliger, Paul, advisor; Bareither, Christopher, committee member; Shuler, Scott, committee memberGranular materials are common in many areas such as civil engineering, food industry,and chemistry. The discrete element method has been demonstrated to be an eectivemethod to study the particle dynamics of such materials over the past several decades. Thepacking of monosized spherical particles has been well studied from both numerical andexperimental perspectives. However, the study of packings of a binary mixture that containsparticles of two dierent sizes has been limited because of the numerous variables that aectthe packing structure.The potential variables for packing of binary mixtures of spherical particles blended bygeometric disruptors in a gravity loaded ramp are evaluated in this thesis. The complexity ofthe disruptor geometry was used as the primary variable to study the resulting packing of twodierent-sized particles. The nal packing structure was quantied by coordination number,radial distribution function, packing density, and vertical position of the smaller-diameterparticles. Based on the analysis conducted in this thesis, the mean coordination number ofall particles, larger particles and smaller particles, generally increases with the complexity ofdisruptor geometry. The mean vertical position of smaller particles decrease with an increasein the complexity of the disruptor geometry. The radial distribution function of each type ofparticle in a binary mixture has the same characteristics of the radial distribution functionof mono-size particle packing. The methodology presented in this thesis can be eective toanalyze binary mixtures of spherical particles.Item Open Access Exploration of passive desaturation of in place tailings using wicking geosynthetics(Colorado State University. Libraries, 2024) Monley, Kendall O., author; Scalia, Joseph, IV, advisor; Bareither, Christopher, committee member; Ross, Matthew, committee memberAs global demand for metals and critical minerals increases, so too does the production of tailings. Tailings are what is left behind after extraction of valuable metals and minerals from ore, and consist of finely ground rock, water, unrecoverable metals, chemicals, and organic matter. These residuals are managed in engineered facilities that function to both dewater and store tailings, known as tailings storage facilities (TSF). A common assumption is that the water initially contained in TSFs will drain down to an unsaturated condition after deposition of new tailings ceases. However, a review of literature on geotechnical and hydrotechnical conditions of legacy TSFs (TSFs that have stopped receiving tailings) in arid environments illustrates that achievement of unsaturated conditions in internal fine-grained layers may not always occur. As the tailings are deposited, layers of finer and coarser particles are interbedded. This causes the formation of capillary barriers and may ultimately result in finer-grained layers held at near saturation after drain down. These fine-grained layers are more susceptible to liquefaction concerns and can require costly remedial actions to ensure geotechnical stability. Dewatering is the process of removing water from whole tailings and offers benefits including increasing geotechnical stability and recovering stored water. Tailings dewatering may occur prior to or after deposition into a TSF. In this study, I explore in-situ dewatering via use of capillary (wicking) geotextiles, and the effectiveness of the wicking geotextiles. Beaker and column experiments were created to emulate stratigraphy seen in legacy TSFs. Additionally, shrinkage testing was conducted to compare the final densities and void ratios of samples with and without wicking geotextiles. Column testing reveals the wicking geotextiles accelerated dewatering by 2.8 times the rate of natural drying processes. At the conclusion of testing, the wicking geotextile experiments had reached similar densities and void ratios to control experiments. This novel approach to passively dewatering tailings warrants additional testing.Item Open Access Flow-generated displacement of reinforced granular slopes using the discrete element method(Colorado State University. Libraries, 2017) Dalaeli, Mozhdeh, author; Heyliger, Paul, advisor; Bareither, Christopher, committee member; Puttlitz, Christian, committee memberThe Discrete Element Method (DEM) has been used by researchers to study the behavior of granular material. It is based on the discrete nature of the granular media and tracks the displacements of individual particles and their interactions at every time-step of the simulation. This approach was used in this study to investigate the flow-generated displacement of spring-reinforced planar granular slopes. A Discrete Element (DE) code was created using MATLAB and FORTRAN to carry out the simulations. The code was validated by comparison of simulation results with analytical solutions. Granular slopes with particle radii ranging from 5 to 10 mm and various initial slopes were generated. Reinforced slopes were created by adding reinforcement, in the form of linear springs restraining surface particles, to the original geometry. The surface of both the original and the reinforced slopes was exposed to flow-generated drag forces. Various reinforcement patterns were modeled and the resulting flow-generated displacements were measured and studied. It was found that slope reinforcing can either delay or prevent flow-generated movements and the effectiveness of the reinforcing depends on the slope of the packing, size of the drag force and the pattern of the reinforcing.Item Open Access Geochemical and mineralogical investigation of breccias at the El Niño Au-Ag Deposit, Elko County, Nevada(Colorado State University. Libraries, 2017) Barker, Rocky, author; Ridley, John, advisor; Singleton, John, committee member; Bareither, Christopher, committee memberTo view the abstract, please see the full text of the document.Item Embargo Improving soil property predictions for applications in tailings and terramechanics(Colorado State University. Libraries, 2024) Bindner, Joseph R., author; Scalia, Joseph, advisor; Atadero, Rebecca, advisor; Bareither, Christopher, committee member; Niemann, Jeffrey, committee member; Ham, Jay, committee memberSoil properties are used by engineers and scientists to better understand the state and behavior of soils. For example, soil properties can be used to estimate surficial soil strength for vehicle mobility models and can be used to better understand the engineering characteristics of mine waste (tailings) stored in tailings storage facilities. Soil and tailings properties often have high spatial variability and often require high resolution data for engineering analyses. Standard laboratory procedures are commonly used to determine soil properties but are often impractical for large spatial extents. While some existing soil data products provide estimates of surficial soil properties, the fidelity of soil data products is often poorly understood and insufficient for many applications. Additionally, some field tests used to estimate soil properties, such as the cone penetration test (CPT), rely on empirical correlations that cannot be used for some soils. There remains a need for procedures which improve the speed and accuracy of soil property estimates across large spatial extents. The objectives of this study are to (i) evaluate how surficial soil moisture and soil strength vary with soil and landscape attributes across a large spatial extent, (ii) explore the use of field-based hyperspectral sensing and machine learning for the prediction of surficial soil properties across a landscape, and (iii) assess the use of laboratory hyperspectral sensing and machine learning for the prediction of tailings properties for potential application in situ via direct push methods. Soil and landscape attributes were determined at sampling locations across a semi-arid foothills region and used to assess how soil moisture and soil strength vary with soil and landscape attributes. Then, hyperspectral data were captured at select sampling locations and used to train and assess the performance of a convolutional neural network (CNN) for the predictions of soil properties. Finally, a diverse tailings-hyperspectral dataset was prepared in the lab and used to train and assess a CNN to provide proof of concepts for prediction of material properties relevant to TSF stability analyses.Item Open Access Numerical simulations of binary mixtures under gravity deposition using the discrete element method(Colorado State University. Libraries, 2021) Jiang, Chao, author; Heyliger, Paul, advisor; Bareither, Christopher, committee member; Ellingwood, Bruce R., committee member; Venayagamoorthy, Karan, committee member; McGilvray, Kirk, committee memberBinary granular mixtures are frequently used in manufacturing, geotechnical engineering, and construction. Applications for these materials include dams, roads, and railway embankments. The mixing process requires dealing with particles with varying sizes and properties, and the complex composite nature of these mixtures can bring unpredictable results in overall performance. At present, there are no specifications for mixing these materials that can be used to quantify the levels of mixing and give estimates of the overall bulk properties. In this study, the Discrete Element Method (DEM) is used to examine the mechanics of the mixing process and give guidelines on how to achieve a well-mixed aggregate. A comprehensive non-linear visco-elastic damping collision model was developed to better represent the interactions between two dissimilar particles. A general Hertz model was applied for describing the normal force but a refined non-linear spring model was generated to imitate the friction force behavior without having to consider the entire loading history. A transition zone revealing the interactions between static and dynamic friction forces was shown in our numerical results. A moment resistance model was also added to capture the behavior of particle surface asperities and the damping force was calculated using relative motion. An alternative condition was applied to determine the end of a collision. Excellent agreement was found with well-established benchmark solutions and new results are also provided for future comparisons. Using this new DEM model, the mixing process of binary unbonded particles was studied using the effects of the number and position of geometric mixing obstacles and the number of mixing iterations. It was found that the mixing degree can be best quantified by measuring the spatial variation of the volume ratio φv. It was also found that small adjustments in the geometric position of the mixing obstacles could have a significant impact on the final mixing parameters. Surprisingly, the results indicate that two mixing iterations provided almost identical levels of mixing regardless of the number and nature of mixing obstacles. Estimates of the bulk elastic constants were provided and showed a high level of anisotropy as measured by the Poisson ratios for the horizontal versus vertical planes of the control volume. Particle crushing is a typical characteristic of many granular materials and can influence the mixing process, and it is possible to model non-particulate materials by bonding individual spheres together. The particle interactions and possibly impact with mixing barriers can result in the fracture of these solids as the allowable bond strength is exceeded. Therefore, the strength of the bond between individual particles that can be part of the mixing process is a critical parameter. The parallel bond model of Potyondy and Cundall (2004) was extended with the present DEM model was used to study the effects of bond strength on the mixing and mechanical properties of binary mixtures. Three types of particle blocks were studied for this purpose: unbonded, weakly bonded, and strongly bonded particles. The bonded particles result in a wider range of reflection angles as the particles interact with geometric mixers and simultaneously change and improve the level of mixing. Overall, these simulations serve to established specific guidelines and provide a basis for field-level mixing operations. They also provide some levels of expectation for the final mixing and bulk elastic behavior for the final aggregates.Item Open Access Petrology and geochemistry of alteration types within a multiphase system and implications for the presence of a porphyry root, Harrison Pass Pluton, Nevada(Colorado State University. Libraries, 2017) Racosky, Alexandra, author; Ridley, John, advisor; Sutton, Sally, committee member; Bareither, Christopher, committee memberTo view the abstract, please see the full text of the document.