Engineering Commons^™

Development Of An Iridium-Ceramic Substrate Catalyst Bed For The Decomposition Of Ionic Green Liquid Monopropellants, Alejandro Andre Vazquez

Open Access Theses & Dissertations

In an effort to advance green monopropellant propulsion using ionic liquids, the Center for Space Exploration and Technology Research (cSETR) has developed a pellet based catalyst bed for the decomposition of AF-M315E. The present paper will go over some of the fundamental research conducted towards the development of a catalyst bed and some of its applications. Three different catalyst bed designs were produced where each uses a different ceramic substrate material. The three different substrates are aluminum oxide, tungstated zirconia, silicon carbide each coated with iridium as the catalyst material. An experimental setup for testing the catalytic decomposition AF-M315E was …

Thermal Characterization Of Abs/Carbon Fiber, Abs/ Glass Fiber And Petg/Glass Fiber Reinforced Composites Used In Large Area Additive Manufacturing, Fernando Adrian Rodriguez Lorenzana

Open Access Theses & Dissertations

Additive manufacturing has seen continuous advancements, such as the inclusion of large-area additive manufacturing extrusion systems. These systems precede small-scale 3D printing by means of research and technological development for the manufacturing of plastic and fiber industries. Big Area Additive Manufacturing (BAAM), a material extrusion process, is capable of 3D printing large parts using thermoplastic composites by adding fiber reinforcements. The incorporation of fibrous materials, carbon fiber (CF) or glass fiber (GF), is a common practice in which percentage nominal ratios of fiber reinforcement by weight are implemented to the polymer matrix. In general, this enables warpage reduction during printing, …

Processing, Structure And Mechanical Behavior Of Advanced Engineering Steels, Bing Yu

Open Access Theses & Dissertations

The concept of low lattice misfit and high-density of nanoscale precipitates obtained through solution treatment was adopted to obtain ultrahigh strength maraging steel without compromising elongation. An "ultrahigh strength-high toughness" combination was successfully obtained in 19Ni3Mo1.5Ti maraging steel with ultimate strength of ~1858 MPa and static toughness of ~110 MJ·m-3. Maraging steel had extremely high density (2.3Ã?1024 m-3) of nanoscale precipitates with minimum lattice misfit of less than 1% at the solutionization temperature of 820 oC. Two kinds of nanoscale precipitates, namely, η-Ni3(Ti,Mo) and B2-Ni(Mo,Fe) contributed to ultrahigh strength. The size of nanoscale precipitates governed the movement of dislocations, cutting …

Cfd Dem Analysis Of A Dry Powder Inhaler, Antara Badhan

Open Access Theses & Dissertations

Dry powder inhalers (DPIs), used as a means for pulmonary drug delivery, typically contains a combination of an Active Pharmaceutical Ingredient (API) and significantly larger carrier particles. The micro-sized drug particles - which have a strong propensity to aggregate and a poor aerosolization performance - are mixed with significantly large carrier particles that are unable to penetrate the mouth-throat region to deagglomerate and entrain the smaller API particles in the inhaled airflow. The performance of a DPI, therefore, depends on entrainment the carrier-API combination particles and the time and thoroughness of the deagglomeration of the individual API particles from the …

In Situ Selective Nitriding Using An Open Source Laser Powder Bed Fusion System, Andres Gerardo Navarro

Open Access Theses & Dissertations

Conventional forms of nitriding titanium limit the locations to surfaces, limiting applications to simple coatings. Additive manufacturing methods provide the opportunity for surface coating methods to be utilized in a layer by layer fabrication method and increase the uses of nitrides. Laser powder bed fusion (LPBF) in particular, provides a fabrication environment with sufficient energy to allow for material nitriding as well as the flexibility of being able to utilize a variety of materials and shielding gases for processing. This project utilizes an AconityONE open source LPBF system with custom laser parameter settings to fabricate and nitride Ti-6Al-4V substrates. This …

Material Characterizations Of Organic-Inorganic Halide Perovskites Using Various Deposition Techniques For Planar Perovskite Solar Cell, Shaimum Shahriar

Open Access Theses & Dissertations

Organic-inorganic halide perovskites have rapidly become emerging materials for photovoltaic applications. Strong characterization methods are needed to fully comprehend the chemistry and composition of perovskite solar cells. Understanding the interaction between layers inside a cell and how they react with the environment is important to achieve optimum manufacturing processes, and improve the efficiency of perovskite solar cells. The present work demonstrates the material characterizations of organic-inorganic halide perovskites using (i) one-step deposition, (ii) two-steps deposition, (iii) solvent-to-solvent extraction, and (iv) mixed-cation solution processing. Investigations by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy (SEM) have been undertaken …

Numerical Investigation Of Molten Metal Infiltration And Pillared Cooling Systems At Microscale, Shaikh Tanveer Tanveer Hossain

Open Access Theses & Dissertations

Flow-through porous media at pore-scales is one of the less explored sides of fluid mechanics due to the complexity associated with highly irregular pore geometry. Most of the established methods that try to quantify such flow are based on statistical observations of flow through numerous porous specimens. Such understandings may satisfy the need for applications where micro-level details are not a concern. Some numerical approaches did try to analyze the micro-level flow, but the analysis was confined to small sample sizes due to the intensive computation challenge. There are several applications of porous media flow where analyzing the large-scale flow …

Additive Manufactured Ear Pinna For Spatial Cue Preservation In Custom Hearing Devices, Carlos Felipe Acosta Carrasco

Open Access Theses & Dissertations

Advancements in additive manufacturing/3D printing technologies has permitted the fabrication of intricate features such as the ones present in the human ear. The outer ear, also known as the pinna, allows for the spectral cues from incoming sound to be captured and identified. The hypothesis of the preservation of auditory localization and externalization relies on the fabrication of an ear pinna via additive manufacturing embedded into a headset for spectral cue preservation and hearing protection. Before exploring these custom circumaural hearing devices, a study on the fabrication process of AM pinnae was performed. The KEMAR system for acoustic research was …

Formulation And Implementation Of Iterative Method For Generating Spatially-Variant Lattices, Manuel Fernando Martinez

Open Access Theses & Dissertations

The use of a matrix-free, memory-efficient approach to generate large-scale spatially variant lattices (SVL) was explored. A matrix-free iterative SVL generation algorithm was formulated and then implemented with a tremendous memory reduction observed. The algorithm consists of solving first-order central finite-differences along the entirety of the problem space point-by-point to obtain the grating phase function Φ(𝑠⃗) to which all desired spatially variant lattice properties are applied to. The algorithm was studied to identify key areas of data and task parallelism to exploit in heterogeneous computing systems consisting of clusters of central processing units (CPU) and graphics processing units (GPU) combinations. …

Segmentation And Registration Based Automatic Cancer Proton Treatment Analysis, Yang Zhang

Open Access Theses & Dissertations

Due to its low side effects, proton therapy is rapidly developing around the world. However, the time and labor it takes to deliver the treatment have prevented widespread use in the clinic setting. For this reason, an automatic proton treatment analysis system is needed to improve efficiency during the treatment process.

The challenge lies in improving the accuracy and speed of the current proton treatment analysis system. The Range shifter correction factor is considered the same value under any given condition in our treatment system. This approximate algorithm limits the accuracy of the proton treatment analysis system. In addition, medical …

Potential Of Nanoscale Elements To Control Fusarium Wilt Disease In Tomato (Solanum Lycopersicum), Enhance Macronutrient Use Efficiency, And Increase Its Yield, Ishaq Olarewaju Adisa

Open Access Theses & Dissertations

Nanotechnology has a great potential in ensuring food production, security and safety globally. Over the past decade, research on the use of nanomaterials to supply nutrient elements and protect plants from pest and diseases has significantly increased. Tomato (Solanum lycopersicum) is one of the most consumed vegetables in the world and United State is one of its largest producers globally generating billions of dollars annually in revenue.. Tomato plants are affected worldwide by Fusarium wilt caused by Fusarium oxysporum f. sp. Lycopersici. There is growing concern about excessive use of conventional pesticides in controlling Fusarium and other diseases in tomato …

Computer-Aided Classification Of Impulse Oscillometric Measures Of Respiratory Small Airways Function In Children, Nancy Selene Avila

Open Access Theses & Dissertations

Computer-aided classification of respiratory small airways dysfunction is not an easy task. There is a need to develop more robust classifiers, specifically for children as the classification studies performed to date have the following limitations: 1) they include features derived from tests that are not suitable for children and 2) they cannot distinguish between mild and severe small airway dysfunction.

This Dissertation describes the classification algorithms with high discriminative capacity to distinguish different levels of respiratory small airways function in children (Asthma, Small Airways Impairment, Possible Small Airways Impairment, and Normal lung function). This ability came from innovative feature selection, …

Raman Computational And Experimental Studies On Label-Free Biological Investigations, John Ciubuc

Open Access Theses & Dissertations

Raman spectroscopy is an optical technique that allows for label-free biological investigations to take place. This approach presents both new perspectives and a means for visualizing investigations. This thesis confronts two biological cases: dopamine (DA) detection at physiological levels and assessment of renal osteodystrophy (ROD). We employed surface-enhanced Raman spectroscopy on silver nanoparticles recording DA concentrations as low as 10−11 molar. Quantum chemical density functional calculations were carried out using Gaussian-09 analytical suite software. Good agreement between the simulated and experimentally determined results indicates the existence of distinct DA molecular forms, such as uncharged DA±, anionic DA−, and dopaminequinone. Disappearance …

Direct Write 3d Printing Of Functional Ceramics, Jorge Angel Diaz

Open Access Theses & Dissertations

Humidity sensors are used in many industries and are important for ensuring quality and safety. Ceramic sensors are preferred because of their quick response time, ability to withstand high temperatures and excellent Chemical and mechanical stability. The manufacturing world has been moving toward additive manufacturing which is a form of synthesizing 3D tangible layer by layer in witch minimal waste is produced. Additive manufacturing also is known as 3D printing has opened new possibilities to design engineers by giving them design freedom and access to the layers of a part to allow embedded sensors. There is a category of ceramics …

Strategies To Improve The Electrochemical Of Performance Transition Metal Compounds As Anode Materials For Li-Ion Batteries, Noemi Dominguez

Open Access Theses & Dissertations

Nowadays, our society depends on fossil fuels as the main energy source. However, depletion, price fluctuations, and other concerns, such as global warming, have led to an exhaustive research for renewable energy resources. Here is where electrochemical energy systems play a critical role since they can provide power when renewable energy is not available. Among these electrochemical energy storage systems Li-ion batteries (LIBs) have shown higher volumetric, gravimetric, and power density capacities over other battery systems.

However, commercial LIBs are still relying on graphite base materials for the anode. However, graphite possesses a low specific capacity. Recently, transition metal compounds …

Incorporating Cybersecurity Engineering Within The Discipline Of Systems Engineering, Chuck Easttom

Open Access Theses & Dissertations

The current study is an examination of integrating cybersecurity and systems engineering. The goal is to provide a framework that accomplishes three objectives. The first is to integrate the existing systems engineering methods into cybersecurity. The second is to provide a template for cybersecurity engineering curriculum. The third is to provide a modeling language specific to cybersecurity.

Characterization And Quality Assessment Of Smart Polymer Systems Fabricated By Using 3d Printing Technique, Carlos Alejandro Garcia Rosales

Open Access Theses & Dissertations

Shape memory polymers (SMPs) are classified as smart materials due to their inherent stimulus-induced response. SMP is capable of recovering its original shape from a high degree of deformation by applying an external stimulus such as thermal energy. Other stimuli are electricity, light, chemical, and magnetic field. Shape memory polymers (SMPs) and its fabrication process has recently attracted much attention as a result of their potential application as soft active materials. Demonstration of SMP systems fabricated via 3D printing technologies has been one of the most popular attempts. This Dissertation presents an integration of two commercial SMP materials (DiAPLEX and …

The Design And Testing Of A 500 Lbf Liquid Oxygen/Liquid Methane Engine, Manuel Jesus Herrera

Open Access Theses & Dissertations

The development of liquid oxygen/liquid methane (LOX/LCH4) propulsion systems has recently become a topic of interest ever since this particular propellant combination was determined to be a suitable candidate for use in space exploration, more specifically missions to Mars. This propellant combination is unique because the propellants can be synthesized from local resources on Mars, a process called In-situ Resource Utilization (ISRU). ISRU would allow for spacecrafts to be lighter and/or increase its payload capacity to Mars-bound missions because the vehicle would not have to store the propellants required for the voyage back to earth.

For this reason, The University …

Understanding Of Deformation And Fracture Behavior In Next Generation High Strength-High Ductility Steels, Venkata Sai Yashwanth Injeti

Open Access Theses & Dissertations

The industrial demand for low density high strength steels without compromising on ductility in is endless. In this regards, grain refinement and austenitic stability considered to the practical approach in order to meet the needs. The concept of phase reversion involving sever cold deformation of metastable austenite to generate strain-induced martensite, followed by time-temperature annealing sequence, was used to obtain varying grain size from nanograined/ultrafine-grained (NG/UFG) to coarse-grained (CG) regime. This concept was used to obtain "high strength-high ductility" combination in nano/ultrafine-grained (NG/UFG) austenite stainless steel. Using this concept, the objective of the study here is to elucidate the dependence …

Computational Studies On Perovskite-Metallofullerene Interface And Magnetic Properties Of Mn-Based Mixed Olivines, Bethuel Omutiti Khamala

Open Access Theses & Dissertations

Methyl ammonium lead halide (MAPbX3) perovskite based solar cells have recently emerged as promising class of materials for photovoltaic applications with efficiencies reaching over 22%. Designing interfaces with strong binding is vital to developing efficient, high-performing solar cells. Fullerene-based materials are widely employed as efficient electron acceptors and can serve as electron transporting layer in perovskite based solar cells. We have studied interfaces of methyl ammonium lead iodide MAPbI3 with Sc3N@C80 fullerene and Sc3N@C80PCBM fullerene derivate within the density functional formalism. Different surface terminations and orientations of the methyl ammonium are examined for binding of the fullerene layer. Our calculated …

Pressureless Sintering Of Zirconium Diboride Obtained By Combustion Synthesis, Gabriel Llausas

Open Access Theses & Dissertations

Magnetohydrodynamic (MHD) direct power generation has the potential to significantly increase the thermal efficiency of coal fired power plants. Materials for MHD electrodes should have high melting points, high electrical and thermal conductivities, and excellent thermal shock and corrosion resistance. Zirconium diboride (ZrB2), which belongs to the class of ultra-high temperature ceramics (UHTC), is a promising material for this application. Mechanically activated self-propagating high-temperature synThesis (MASHS) is an attractive method for its fabrication. Previous studies have shown that zirconium diboride can be fabricated from inexpensive oxides of zirconium and boron (ZrO2 and B2O3) using magnesium as a reducing agent and …

Materials Characterization In The Development Of Combustion-Based Methods For Synthesis Of Niobium Silicides, Edgar Maguregui

Open Access Theses & Dissertations

The use of characterization techniques is essential for a better understanding of novel manufacturing processes and for investigating how the process parameters affect the products. Mechanically activated self-propagating high-temperature synthesis (MASHS) is an attractive method for the production of high-temperature structural materials. In the present work, it was used to fabricate Nb5Si3 compound and Nb5Si3/Nb composites. It has been shown that for mechanical activation of Nb/Si mixtures, a planetary ball mill is more effective than a shaker ball mill used in prior research on MASHS of Nb5Si3. The influence of mixture composition and experimental parameters, such as milling time and …

Applications Of A New Genetic Algorithm To Solve The Centralized Carrier Collaboration And Multihub Location Problem Considering Environmental Impacts, Eduardo Jose Castillo Fatule

Open Access Theses & Dissertations

The Centralized Carrier Collaboration and Multi-hub Location Problem (CCCMLP) represents a strategy that small-to-medium sized less-than-truckload (LTL) carrier companies can use in order to improve their profit margins. It is a strategy that is being explored in order to make these companies more sustainable as they are forced to reinvent their processes and supply chains. In this work, I will present a metaheuristic approach to optimizing their hub establishment and routing policies in order to better their expected profit margins and reduce their environmental impacts. The study considers the costs of transportation, loading and unloading, maintenance, operations, and inventory holding …

Comparative Study Of Analytical Models Of The Gruneisen Parameter Of Metals As Function Of Pressure, Celia Garcia Amparan

Open Access Theses & Dissertations

Commonly used Gruneisen parameter (γ) models only hold accurate in limited regimes making them inapplicable for use over wide temperature-pressure conditions. The accuracy of these analytical models of γ and of the thermal expansion of solids are of particular interest as these are considered proxies for quantifying anharmonicity, which may be a significant contribution to the thermal pressure at high temperatures. This work reviews various definitions of γ and their relations to the equations of state and apply them to two simple metals: Tantalum (Ta) and Copper (Cu), for which a high body of experimental data exists. Classical Molecular Dynamics …

Development Of Actuators Using Material Extrusion Additive Manufacturing With Embedded Shape Memory Alloy Wire, Alfonso Fernandez

Open Access Theses & Dissertations

Over the past several decades, the advancements in Additive Manufacturing (AM) technologies have opened a wide variety of applications where AM can be used. Some examples of these advancements are the introduction of automatic wire embedding capabilities, the introduction of multi-material processing and the printing of thermoplastic elastomers. With the availability of these advancements, it is now possible to create spark-free, dust-free actuation mechanisms for applications where it is crucial that no spark is generated (i.e. space shuttle fuel valve).

In this research, a Lulzbot TAZ 6 desktop material extrusion system was utilized to print parts out of Plasticized Copolymer …

Varying Ratios Of Collagen I And Iii For The Study Of Fibrotic Conditions In Tissue Engineering, Brian Roman

Open Access Theses & Dissertations

Maintenance of collagen I (Col I) and III (Col III) in a 3:1 ratio is necessary to promote cardiac health. Increase in the relative amount of Col I within the myocardium, leads to an imbalance of Col I:III during cardiac fibrosis, which has damaging effects on cardiomyocytes (CM). To represent fibrous- and normal-cardiac tissue, gels composed of Col I:III ratios of 9:1 and 3:1 were developed and used to study resultant changes in CM function. Second harmonic generation (SHG) microscopy, used to image Col I fibers, displayed a decrease in image intensity with the addition of the non-second harmonic Col …

Load Rating Mobility As A Framework For Bridge Owners, Bryan Keith Stephens

Open Access Theses & Dissertations

In this time of financial economy, bridge owners are faced with the important decision of where to focus financial assets while attempting to determine which structures are in most need. Bridge Engineers and researchers alike agree that a large portion of the United States bridge population are reaching the end of their design life. Researchers are currently investigating various means and methods of lengthening the amount of usefulness of these key pieces of infrastructure. This paper introduces the novel idea of bridge Load Rating Mobility and how it can be leveraged by stake holders to assist in making those financial …

Investigating Using Titanium Zirconium Molybdenum For Additively Manufacturing Aerospace Components, Justin Hunter Vanhoose

Open Access Theses & Dissertations

Mankind throughout history has possessed an innate characteristic to explore, migrating to new frontiers.The requirement for this travel is most broadly associated with the need to pursue more resources. Rockets have been used as a means of weapons since the Sung Dynasty in the thirteenth empire and have now been integrated for travel/transport. The sophistication of rocketry and propulsion has reached a level to where it is plausible that mankind will be a multi-planetary species. The space industry has grown significantly with the advancement of the sophistication of these rocket technologies. However, a specific challenge to overcome in the space …

Conductivity Modulation In Strained 2d Transition- Metal- Dichalcogenides Via Micro- Electro- Mechanical Actuation, Aldo Ivan Vidaña

Open Access Theses & Dissertations

In this thesis, strain-induced conductivity modulation in bi-layer molybdenum disulfide (MoS2) flakes is experimentally investigated and modeled. Uniaxial tensile strain in the MoS2 flakes is achieved using a micro-electro-mechanical (MEM) actuator. Conductivity ratios up to 400 are demonstrated. Theoretical predictions of conductivity versus applied voltage in the MEMS-MoS2 device match experimental data reasonably well using only the effective width of the TMDC flakes as the sole fitting parameter. The amount of strain induced in the MoS2 flakes was determined to be as high as 2.7% for one flake using the model fitted to the experiment data. The switching energy required …

Thermo-Fluid System Level Modeling For The Crome And Crome-X Ground Propellant System Using Generalized Fluid System Simulation Program, Mariano Mercado

Open Access Theses & Dissertations

A recent resurgence of interest in space exploration has given rise to a number of newcomers in the space industry. A number of private companies like SpaceX, Blue Origin, and United Launch Alliance have joined the likes of NASA with the goal to expand the current capabilities of space travel and exploration. Perhaps the most ambitious of these goals is a manned mission to Mars. In order to achieve this goal, many of these companies have taken a keen interest in liquid oxygen and methane engine technologies. Engines like the Raptor by SpaceX and the Blue Origin BE-4 already run …