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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

<b>Investigation of Additively Manufactured Silver Plated Stainless Steel Monolith Catalyst Beds</b>

Amelia Jane Farquharson (19180201) 19 July 2024 (has links)
<p dir="ltr">Additive manufacturing has introduced new possibilities for the design and manufacturing of monolith catalyst beds. Many hydrogen peroxide monolith catalyst beds are made of ceramics and washcoated through a complex process. However, creating a metal monolith bed with the tried-and-true silver catalyst could provide an alternative decomposition method for 90 wt.% hydrogen peroxide with easier manufacturing methods and similar or better decomposition efficiency. 91.2 wt.% hydrogen peroxide was decomposed with a lattice-type monolithic catalyst bed additively manufactured out of 316L stainless steel that was electroplated with pure silver. The variables investigated included the catalyst bed’s mass loading, chamber pressure, pressure drop, and length-to-diameter ratio (L/D). The catalyst bed had loadings of 0.1 lb<sub>m</sub>/s/inch<sup>2</sup>, 0.25 lb<sub>m</sub>/s/inch<sup>2</sup>, and 0.4 lb<sub>m</sub>/s/inch<sup>2</sup>. One catalyst bed configuration had an L/D of 2.6, while the other configuration had an L/D of 0.85. A modular throat controlled the chamber pressures for each catalyst bed loading case. The decomposition efficiency was calculated with the theoretical and expected characteristic velocity (c*) of the catalyst beds. The chamber pressures for the lowest bed loading and highest L/D ratio varied from 52 psia to 202 psia. The hydrogen peroxide decomposition efficiency was approximately 85% for the lowest chamber pressure and approximately 100% for the highest chamber pressure. The chamber pressures for the middle and highest bed loading and high L/D were 193 psia at the lowest to 325 psia at the highest. The decomposition efficiencies for all middle and highest bed loading tests with high L/D were 90% or higher for all tests. For all of the highest L/D tests, decomposition was also confirmed by observing videos of the exhaust plume, which was clear and showed no sign of flow channeling. For all of the highest L/D tests, the pressure drops in all of the middle bed loading cases were at or below 30% of the chamber pressure. The high chamber pressure, highest bed loading cases also had a pressure loss below 30% of the chamber pressure. The smallest L/D configuration performed significantly worse than expected, with efficiencies between 15-25% at chamber pressures between 33-75 psi. The silver electroplated on the stainless steel survived the 143 s of lifetime on the catalyst bed during testing with minimal to no silver loss determined by weight and visual inspection with a microscope post-test. The higher L/D catalyst bed tests prove that silver electroplated on to an additively manufactured stainless steel monolith is a viable method for creating a catalyst bed. More research is required to determine the lowest L/D possible, which resides somewhere between the two L/D cases studied, and higher bed loadings also require investigation.</p>
52

<b>EFFICACY IN LOW-COST KINETIC APPREHENSION COUNTER DRONE SYSTEM</b>

Kar Ee Ho (19183450) 25 July 2024 (has links)
<p dir="ltr">This dissertation presents the design, development, and testing environment of a low-cost, self-built ground based Counter Unmanned Aerial or Aircraft Vehicle (CUAV) system aimed at providing effective aerial security solutions in resource-limited environments. The kinetic CUAV technique was selected and identified for the current study as it is the most feasible, low-cost and reusable mitigation path as last-resort defense. Utilizing commonly available materials, including parts from online retailers and hardware stores, and incorporating a self-made pneumatic system with a reusable 3D-printed projectile and interchangeable parts design. This study explores the feasibility of cost-effective drone defense and introduces a short-range accuracy metric to evaluate the system’s trajectory behavior. Through rigorous indoor testing in Purdue University Hangar 4, the research evaluates the system's performance in terms of projectile height, range, and accuracy under various environmental conditions. A 90 degrees field of view of pneumatic launcher was tested with a small error margin comparison table to highlight on areas for potential technical refinement. TPU filament was found to be the best material for this study, with 10% infill, printing temperature in 225°C (437°F), and 70 mm/s printing speed settings for the 3D-printed projectile (4.16a). These findings in Figures 4.10, 4.11, 4.12, 4.13 will significantly advance the research of low-cost drone defense technologies by providing empirical evidence on material and design choices that will impact the system performance. Findings indicate that the system’s performance is affected by the climate temperatures, which influences its consistency in different settings. This offers practical implications for enhancing security measures against unauthorized drones using similar technology. The study fills a significant gap in current drone defense technologies with kinetic apprehension by proving that effective solutions can be both affordable and accessible. This work not only contributes to the advancement of counter drone technology but also encourages ongoing design innovation in the field, paving the way for further research and development into scalable and adaptable drone defense systems.</p>

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