Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
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Item Wireless sensor network development for the purpose of measuring acceleration in snow(Montana State University - Bozeman, College of Engineering, 2023) Lesser, James Byron; Chairperson, Graduate Committee: Edward E. AdamsA WSN (Wireless Sensor Network) was developed for the purpose of measuring snow acceleration in response to loading of various types. In its current state, the WSN is composed of seven nodes (radio enabled sensors) and one controller. Two dynamic ranges, +/- 10 g and +/- 40 g, allow for user adjustment based on the required sensitivity of measurement. Acceleration data is logged simultaneously across all active nodes; data from an analog accelerometer is stored by each node on a microSD card. Data throughput limits the maximal sampling frequency to 10 kHz at 8-bit precision, or 5 kHz at 10-bit precision. Empirical investigation of GEM (Green Environmental Monopropellant) as a tool for avalanche mitigation was conducted with the first iteration of the WSN. The GEM explosive is compared with the industry standard, Pentolite; the metrics of comparison are those of overpressure, impulse per unit area, and the resulting snow acceleration. This study showed the effectiveness of the WSN as a tool for measuring snow dynamic response under explosive loading. Additionally, an ECT (Extended Column Test) instrumented with the WSN on this day elicited continued development of the WSN. A detailed look at the components of the WSN provides the physical and electrical qualities focused on the nodes intended environment - seasonal snow. Theory of operation, and a standard operating procedure, provide fundamental knowledge for the end user. Modal testing was performed to characterize the vibration response of the node. Natural frequencies are identified within the bandwidth of the accelerometer, and it is shown that these frequencies are not present in signals collected in snow under impulsive loading. Acceleration data acquired by the WSN in a series of stability tests, conducted in the lab and in the field, demonstrate the utility of the system.Item Measuring explosive airblast of remote avalanche control systems(Montana State University - Bozeman, College of Engineering, 2021) Seitz, Brandt Kolden; Chairperson, Graduate Committee: Robb LarsonThis research was established to evaluate the explosive blast waves from operational remote avalanche control systems (RACS). Testing was performed on Gazex, O'Bellx, and Wyssen Tower systems installed near Alta, Utah. Air pressures were measured in many directions and at a range of distances around each explosive using high-pressure microphones and custom measurement equipment. The air pressure data from each system was then evaluated based on the peak pressures generated, effective blast wave energy, the rate at which pressure increased, and the decay of these parameters with distance. Distinct differences, and some similarities, between the explosives tested were found that both validated and expanded upon previous research efforts. It was found that an 11-lb Pentolite charge (designed to be deployed from a Wyssen Tower) had the strongest effects overall, followed by the standard 11-lb gel emulsion charge from a Wyssen Tower, then by the 1.5 m 3 Gazex system (which was comparable to the gel charge in the direction of the exploder, but weaker in other directions), and lastly by the O'Bellx system (which had a more localized, but more symmetric, effect than the Gazex). In addition, many other tests were conducted utilizing 2-lb Pentolite charges, simulated Avalanche Guard charges, flat-field testing of Wyssen Tower gel emulsion and Pentolite charges, and explosives or RACS placed near unique terrain features. The 2-lb Pentolite testing validated the instrumentation for this project and showed that the equipment performed similarly to other systems from prior research efforts. The simulated Avalanche Guard charge was shown to have a very similar effect to the 11-lb gel emulsion charge. Flat-field testing of the Wyssen Tower charges showed similar blast wave strengths as was observed at the operational tower but indicated differences in the symmetry of the waves when compared to the operational tower. Lastly, the initial investigation of terrain features indicated that features such as cliffs and gullies can increase the directionality of an explosive. Overall, this work will provide avalanche control experts with much needed performance data on operational RACS and will also help to facilitate future work in this subject area.Item Chromatographic, spectroscopic and microscopic analyses reveal the impact of iron oxides and electron shuttles on the degradation pathway of 2,4,6- trinitrotoluene (TNT) by a fermenting bacterium(Montana State University - Bozeman, College of Agriculture, 2003) Borch, Thomas; Chairperson, Graduate Committee: William P. Inskeep and Robin Gerlach (co-chair)Contamination of surface and subsurface environments with explosives such as 2,4,6-trinitrotoluene (TNT) is a worldwide problem. The fate and analysis of TNT were investigated in numerous artificially contaminated model systems. We developed a unique high performance liquid chromatography gradient elution method for the analysis of commonly observed TNT metabolites and EPA explosives. Column temperature was identified as the key parameter for optimal separation. Iron (hydr)oxides play an important role in the reduction, sorption and fate of TNT in soil and sediment. Consequently, characterization of the nature and properties of natural and synthetic Fe (hydr)oxides is important for determining reaction mechanisms and surface-associated chemical processes. This work thus summarizes the potential applicability of imaging and spectroscopic techniques for eliciting chemical and physical properties of iron (hydr)oxides. TNT is persistent in soils due to its low redox potential and sorption. Batch and column studies revealed some of the first results on TNT desorption behavior in two well-defined model soil systems. Biosurfactants were found to be the most promising technique for enhanced TNT desorption. Batch studies with a Cellulomonas sp. in the presence of ferrihydrite and the electron shuttle anthraquinone-2,6-disulfonate (AQDS) were conducted to reveal biotic and abiotic mechanisms contributing to the degradation of TNT. Strain ES6 was found to reduce TNT and ferrihydrite with enhanced reduction in the presence of AQDS. Ferrihydrite stimulated the formation of more reduced TNT metabolites such as 2,4-diamino-6-nitrotoluene. Interestingly, a completely different degradation pathway was observed in AQDS-amended iron-free cell suspensions, showing a rapid transformation of TNT to 2,4-dihydroxylamino-6-nitrotoluene, which transformed into unidentified polar products. The influence of iron phases (i.e. hematite, magnetite, and ferrihydrite) and secondary Fe mineral formation on the degradation of TNT was also evaluated. The initial reduction of TNT was fastest in the presence of hematite; however, the further reduction of hydroxylamino-dinitrotoluenes was fastest, in the presence of magnetite and ferrihydrite (no AQDS). The impact of AQDS was predominant in the presence of hematite resulting in the formation of 2,4,6-triaminotoluene. Ferrihydrite underwent reductive dissolution with the formation of secondary hematite. The enhanced TNT reduction in ferfihydrite-amended systems was therefore most likely due to redox-active Fe(II) rather than secondary Fe phases.Item Experimental investigation of interactions between explosive detonations and the resulting snowpack response(Montana State University - Bozeman, College of Engineering, 2012) Bones, Josephine Anne; Chairperson, Graduate Committee: Daniel MillerAvalanches threaten many areas of the world. For many years, risk has been mitigated through artificial avalanche initiation using explosives. Even with extensive use, a lack of experimental determinations of the interactions between explosive detonations and the snowpack response exists. To address this, a multiyear field based research project was conducted at Montana State University, Bozeman, MT. A portable instrument array consisting of pressure and accelerometer sensors was fabricated and utilized to record the overpressure and acceleration of the snowpack resulting from detonation of pentolite cast boosters. Explosives were detonated 0-2 m above the snow surface, at 0.5 m increments. All sensors were placed within a 7 m radius of the explosive in soft slab and hard slab snow conditions. The data was used to characterize relationships between explosive size and location to the resulting overpressure and snow acceleration based on various snow parameters. The snow surface was shown to be able to reflect shockwaves, thus, increasing the shockwave pressure. It was shown that elevating an explosive off the snow surface resulted in greater overpressure and peak snowpack acceleration than surface detonations. Elevating an explosive was found to not influence the vertical or radial attenuation. Therefore raising a charge increased the volume of influence. Overpressure and acceleration were shown to be nonlinearly related to the explosive mass. Doubling the mass resulted in less than double the response. The acceleration of moist snow was determined to be less and the attenuation greater than for dry snow conditions. Hard slab conditions indicated lower acceleration and greater shockwave attenuation than soft slab snow. Snowpack peak acceleration and attenuation were shown to have little dependence on either the total snow water equivalent or snow density. For rock bed surfaces the shockwave was reflected back through the snow while meadow bed surfaces did not. This project verified past theoretical and experimental results, but further research would be beneficial for avalanche mitigation work. A continuation of this work could lead to increased efficiency and safety for the avalanche community.Item The effects of explosives on the physical properties of snow(Montana State University - Bozeman, College of Letters & Science, 2013) Wooldridge, Robyn Elaine; Chairperson, Graduate Committee: Jordy HendrikxExplosives are a critically important component of avalanche control programs. They are used to both initiate avalanches and to test snowpack instability by ski areas, highway departments and other avalanche programs around the world. Current understanding of the effects of explosives on snow is mainly limited to shock wave behavior demonstrated through stress wave velocities, pressures and attenuation. This study seeks to enhance current knowledge of how explosives physically alter snow by providing data from field-based observations and analyses that quantify the effect of explosives on snow density, snow hardness and snow stability test results. Density, hardness and stability test results were evaluated both before and after the application of 0.9 kg cast pentolite boosters as surface and air blasts. Changes in these properties were evaluated at specified distances up to 5.5 meters (m) from the blast center for surface blasts and up to 4 m from the blast center for air blasts. A density gauge, hand hardness, a ram penetrometer, Compression Tests (CTs), and Extended Column Tests (ECTs) were used. In addition to the field based observations, the measurement error of the density gauge was established in laboratory tests. Results from surface blasts did not provide conclusive data. Air blasts yielded statistically significant density increases out to a distance of 1.5 m from the blast center and down to a depth of 50 centimeters (cm). Statistically significant density increases were also observed at the surface (down to 20 cm) out to a distance of 4 m. Hardness data showed little to no measurable change. Results from CTs showed a statistically significant decrease in the number of taps needed for column failure 4 m from the blast center in the post-explosive tests. A smaller data set of ECT results showed no overall change in ECT score. The findings of this study provide a better understanding of the physical changes in snow following explosives, which may lead to more effective and efficient avalanche risk mitigation.