Engineering Commons^™

Synthesis And Characterization Of Novel Lithium Gallium Phosphate (Ligap2o7) For Extreme Environment Applications, Mohan Raj Rajkumar

Open Access Theses & Dissertations

In this work, we report on the synthesis, characterization, and performance of LiGaP2O7 (LGP), a novel material and fairly new to the scientific & engineering community. LiGaP2O7 materials were was synthesized using the conventional high-temperature, solid-state ceramic reaction. Calcination was done in three steps at the temperatures of 300 °C, 500 °C, and 650 °C for 8 h each to ensure a single phase. Utilizing this, different green pellets were sintered at 800 °C for varying times of 3 h, 6 h, 12 h, and 24 h. The structure, phase, and morphology were analyzed using X-ray diffraction (XRD) and scanning …

Multi-Wavelength Pyrometry For Emissivity Mapping And Accurate Surface Temperature Measurement In Powder Bed Fusion Systems, Md Moinuddin Shuvo

Open Access Theses & Dissertations

Accurate surface temperature measurement within powder bed fusion (PBF) systems during fabrication remains elusive for many reasons, despite the importance of knowing temperature for improving part quality, process control, repeatability and reproducibility, simulation capabilities, and more. Multi-wavelength (MW) pyrometry has been used previously to measure off-axis temperatures of a small region (~2.6mm in diameter) within an electron beam PBF (EBPBF) system. While this small region measurement makes it difficult to get a full field temperature map of the powder bed, it also allows for inline (on-axis) with laser temperature measurements for laser PBF (LPBF) systems. The MW pyrometry technique determines …

Mechanically Activated Combustion Synthesis Of Niobium Silicide Based Composites, Reina Trevino

Open Access Theses & Dissertations

Niobium silicide-based composites are promising materials for high-temperature structural applications, such as gas turbines, but their implementation is hindered by the lack of effective processing methods. Self-propagating high-temperature synThesis (SHS) is an attractive method for fabrication of advanced materials. However, it is difficult to perform SHS of niobium silicides because the melting point of Nb is higher than the combustion temperature, which greatly inhibits Nb-Si reaction. To ignite an Nb/Si mixture and obtain Nb5Si3, the desired phase in niobium silicides, either preheating or mechanical activation of the mixture is necessary. This problem becomes even more critical in the SHS of …

Life Cycle Studies To Evaluate The Physiological And Biochemical Effects Of Copper Oxide And Surface-Coated Titanium Dioxide Nanoparticles On Green Onion (Allium Fistulosum) And Carrot (Daucus Carota L.) Plants: Insights Utilizing Two-Photon Microscopy And Spectroscopy, Yi Wang

Open Access Theses & Dissertations

With the recent increase of nanomaterial production, nano copper oxide (nCuO) and surface-modified titanium dioxide nanoparticles (nTiO2) are among the most widely applied nanoparticles in industry and daily lives. Their use has resulted in accumulation in soils as a consequence of their direct or indirect release. Hence, these NPs may raise a potential risk to crops cultivated in soils. Moreover, the physiological effects of nCuO on green onion (Allium fistulosum) and surface-coated nTiO2 on full-grown carrot (Daucus carota L.) are still unknown. Green onion is characterized by its high content of the antioxidant allicin, and carrot is a worldwide economic …

Qualification And Implementation Of A Liquid Oxygen/ Liquid Methane Data Acquisition System, Zachary Welsh Welsh

Open Access Theses & Dissertations

One of the primary goals of the MIRO Center for Space Exploration and Technology Research (cSETR) is the design and testing of liquid oxygen and liquid methane rocket engines. As of this thesis’ time of writing, two engines are currently undergoing testing at the center’s Technology Research and Innovation Acceleration Park (tRIAC), located in Fabens, Texas. The engines vary in scale starting with a 5 lbf Reaction Control Engine (RCE) to a 500 lbf engine dubbed the Centennial Restartable Oxygen Methane Engine (CROME). It was necessary to develop a control and data acquisition system to support these various test campaigns, …

Multiple Change-Point Modeling Of Degradation Signal For Prognostics Improvement, Yuxin Wen

Open Access Theses & Dissertations

To fulfill the increasing demand on functionality and quality, modern engineering systems are usually built with overwhelming complexities. The more complex functions the system has been built, the higher reliability required of the system. This is mainly due to the fact that a single failure can result in catastrophic consequences. Therefore, methods that can predict and prevent such catastrophes have long been explored. Prognostics refer to the process of evaluating the current health of a system or a component and then predicting the remaining useful life (RUL) based on the information collected through condition monitoring. The fast development of information …

Effect Of Flow Velocity And Geometry On The Signal From A Piezoelectric Flow Rate Sensor, Jad Gerges Aboud

Open Access Theses & Dissertations

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Forecasting Consumer Consumption Behavior Of Water Bottles Using Generlized Linear Model For Supply Chain Resilience, Abdulaziz Alidrees

Open Access Theses & Dissertations

When forecasting the amount of water consumed by individuals at Kuwait's Mubarak Al-Kabeer city Block 8, it is important for any water producing company to tell the amount of water they should produce for its target consumers. After interviewing a couple of residents in this block, it was discovered that they were restricted by being unable to shop for their essentials, including water packs. Data on the amount of water consumption in milliliters for different individuals were collected and recorded. Generic scanners and smartphone scanners were installed in 20 different households that rely on water packs instead of central water …

Accurate Replication Of An Ear Pinnae Geometry For Use In Acoustic Testing Of Spatial Cues And Sound Localization, Alejandra Belmont

Open Access Theses & Dissertations

Additive manufacturing (AM) enables freedom of design as well as fabrication of complex objects such as the human hear. In medical modeling there is a need for patient-specific customizable parts. The outer human ear consists of these main parts: the pinna, which naturally filters sound, and the ear canal, which is the point at which sound enters before being moved up to the tympanic membrane, otherwise known as the eardrum. In an attempt to accurately replicate ear models, the use of scanning and reverse engineering methods was used. A comparison of 3D laser scanning systems was performed to determine their …

The Dynamic Transition Of A Vertical Take-Off And Landing Drone, Luis Carlos Calvo Jr.

Open Access Theses & Dissertations

Unmanned aerial vehicles, or UAVs, are small pilotless aircrafts that are remotely controlled through a ground control station. They have increased in popularity because of their applications and the advantages that each UAV can provide based on their need. There are many types of UAVs, but this study focuses on a type of Vertical Take-Off and Landing (VTOL) UAV that is known as the Albatross UAV. This UAV was manufactured by a company known as Applied Aeronautics, and configurations were made to change the fixed-wing (FW) UAV to a VTOL UAV. This study was done to find methodologies to simulate …

Design And Additive Manufacturing Of Shape Recovery Polymer Lattice Structure, Chien-Chun Chou

Open Access Theses & Dissertations

Studied mechanical properties of 3D printed metamaterials of BCC, FCC, and BFCC structure.

Mathematical Modeling, Optimal Control And Stability Analysis For Dynamic Supply Chains, Yasser Alberto Davizon

Open Access Theses & Dissertations

Dynamic supply chains (SC) are important to reduce inventory, to enable the flow of materials, and maximize profits. By this, dynamic SC require proper decision-making with effective performance and synchronization. In operations and production planning processes, decision-makers develop convenient and suitable decisions, to validate their hypoThesis about which decisions incorporate more profit while reducing costs on enterprise operations. Based on this, inventory management plays a crucial point in the supply chain analysis. In general, SC processes raw material, cash, and information flows, taking into account the demand profile of the system. This research work presents the mathematical modeling, optimal control, …

Development Of Software Tools And Experimental In Situ Electron Spin Resonance For Characterizing The Magnetic And Electrocatalytic Properties Of Transition Metal Chalcogenide Crystals, Jose Armando Delgado

Open Access Theses & Dissertations

Studying the magnetic properties and crystal defects of transition metal chalcogenide crystals is of paramount importance for utilizing them for next generation spintronics devices and hydrogen evolution reaction catalysts. Hydrothermally grown transition metal chalcogenide nanocrystals (MoS2, Ru2S3, Rh2S3, Co2S8) were chosen as catalysts for the hydrogen evolution reaction due to their low dimensionality and previous utilization as catalysts for hydrodesulfurization. The relationship between crystal defect sites and catalytic activity must be discerned to maximize the efficiency of hydrogen production during the hydrogen evolution reaction. ESR spectroscopy was utilized as a spin sensitive technique to study the defects and local changes …

Uav Parameter Estimation Through Machine Learning, Andres Enriquez Fernandez

Open Access Theses & Dissertations

Parameter identification of Unmanned Aerial Vehicles (UAV) is very helpful for understanding cause-effect relationships of physical phenomenon, investigating system performance and characteristics, fault diagnostics, control development/tuning, and more. Traditional ways of performing parameter identification involve establishing a mathematical model that describes the system's behavior. The equations in the model contain parameters that are estimated indirectly from measured flight data. This parameter identification process requires knowledge of the physics involved. Also, it necessitates a careful consideration of the aircraft instrumentation for accurate measurements. It also requires careful design of the flight maneuvers to ensure thorough excitation of the flight dynamics involved. …

Effect Of Temperature On A Piezoelectric Mass Flow Rate Sensor Signal, Lyan Eduardo Gutierrez Hernandez

Open Access Theses & Dissertations

On this research, we are trying to demonstrate that a piezoelectric flow sensor made of PZT can produce a higher and fluctuating signal when exposed to elevated temperatures presented on the system. This type of application can be beneficial for systems that involve changes in temperature such as compressors and be able to predict certain situations presented on those systems that can be catastrophic, that is the case for surge and stall. Therefore, a system capable of going from 25â?°C-90â?°C was designed where a piezoelectric sensor was inserted at a specific location to analyze the signal produced by these changes …

Development Of Recepticals And Joints For Embedded Electronic Components Inserted During Print Via Hybrid Thermoplastic-Based Additive Manufacturing, Leonardo Isaac Gutierrez Sierra

Open Access Theses & Dissertations

The use of hybrid additive manufacturing (AM) systems is a novel approach in the fabrication of multi-functional parts. 3D printed electronics are an example of multi-functional parts fabricated using the Foundry Multi3D System, a hybrid AM system. Previous research has demonstrated the capabilities of the system by manufacturing RF antennas and satellite panels with embedded electronics, to name a few. However, research to identify design clearances and establish a manufacturing process plan had not been performed. The purpose of this manuscript is to determine the correct clearances for foreign components to be inserted unto a partially printed substrate. Besides this …

Mechanical Performance Of Ebm Ti-6al-2sn-4zr-2mo Influenced By The Effects Of Different Hot Isostatic Pressing Treatments, Miguel Lopez

Open Access Theses & Dissertations

Electron Beam Melting (EBM) is an additive manufacturing process that presents a lower level of internal defects in comparison to Selective Laser Melting (SLM). Pairing Hot Isostatic Pressing (HIP) with Additive Manufactured metal parts, sub-surface voids can be eliminated through high pressure and temperature. This significantly improves fatigue life, impact toughness, creep, rupture strength, and tensile ductility. In this investigation, Ti-6Al-2Sn-4Zr-2Mo samples manufactured in the Arcam's Q20 system will be tested as per ASTM E8 Standard Test Methods for Tension Testing of Metallic Materials. Different variants of Hot Isostatic Pressing (HIP) treatments were analyzed and compared. Tensile testing was performed …

Planar Motion Control Of A Cube Satellite Using Cold Gas Thrusters, Christian Lozoya

Open Access Theses & Dissertations

This Thesis presents a mathematical model developed for the computational simulation ofCubeSat movement using four thrusters that permit uniaxial translation and rotation. Arbitrary functions are fit to boundary conditions to simulate the force, acceleration, velocity, and displacement of the CubeSat along a plane. The model is used to derive a motion control algorithm assuming constant pressure and mass. A single model describes both translation and rotation. This Thesis also explores the relationship between propellant consumption and the time required to complete a displacement implied by the model.

Development Of An Automated Ultrasonic Wire Embedding Process For Use With Material Extrusion Additive Manufacturing And Rapid Electronics Fabrication, Nikki L. Martinez

Open Access Theses & Dissertations

Polymers have been used in Additive Manufacturing (AM) by many industries for rapid prototyping. Parts created using polymer AM however are known to be relatively expensive thus limiting them to small volume production and making them inapplicable for mass production, while their inherent porous and anisotropic properties make them mechanically inferior to parts made using traditional methods such as injection molding. As projects demand more efficient designs, and at the same time ask for more complex features, AM, combined with other manufacturing processes, like Ultrasonic Wire embedding, can streamline and consolidate assemblies. In the realm of composite and multifunctional assemblies, …

Performance Measure Methodology Of Project Management Practices In Local Government Agencies, Johanes Johanes Makahaube

Open Access Theses & Dissertations

Local government agencies have adopted project management practices to deliver public work projects. The agencies need to measure project management performance to ensure the consistency, control, and monitoring of the project delivery process. However, local government agencies have not adopted a systematic method to measure the organization's project-management performance. At present, there is a gap regarding methods to measure project management performance in delivering construction projects. This study aims to assist local government agencies in improving their project management processes by implementing a comprehensive methodology to assess project management's performance. This dissertation is organized into three major chapter-papers: the first …

Design Of Experiments Analysis Of Powder Removal Methods For Ebm Manufactured Ti-6al-4v Parts, Luis Cesar Ramos Castañeda

Open Access Theses & Dissertations

Additive Manufacturing is a technology that allows the on-demand manufacturing of complex geometries that cannot be fabricated through traditional subtractive manufacturing methods. Powder Bed Fusion is one of the seven categories of Additive Manufacturing with two subcategories, the Laser Beam Melting and the Electron Beam Melting. Freedom of design, rapid prototyping, and customization are some of the benefits that this technology provides. Like any technology, there are limitations for each category and subcategory. The Electron Beam Melting uses the electron beam to pre-heat the powder bed, reducing the temperature difference between the build part and powder bed, causing the surrounding …

Performane Characterization Of Stabilized Materials In Pavement Foundations, Mohammad Rashidi

Open Access Theses & Dissertations

Cementitious Stabilization has been widely used to improve the strength and durability of granular materials for the construction and rehabilitation of pavement structures. Improved mechanical properties and durability of the stabilized materials combined with relatively low cost makes it an attractive method for design engineers. Although this technique appears simple and straight forward, engineering properties of individual soils and aggregates may alter widely due to heterogeneity in soil composition, difference in micro structure among soils, heterogeneity of geologic deposits and differences in chemical interactions of water with soil particles. These differences necessitate the comprehensive study in order to provide the …

Impact Of Cryptococcus Neoformans Polysaccharide Capsule On Astrocytes, Yeon Hwa Woo

Open Access Theses & Dissertations

Cryptococcus neoformans is a neurotropic, opportunistic, encapsulated, yeast-like fungus that causes life-threatening meningoencephalitis in both healthy and immunocompromised individuals. C. neoformans infects 1,000,000 people and causes 210,000 deaths worldwide annually, mostly in sub-Saharan Africa. The polysaccharide capsule of C. neoformans is the fungus major virulent factor. Glucuronoxylomannan (GXM), the main component of the capsule is abundantly released into brain tissue during C. neoformans infection, causing immunosuppressive defects in the host. C. neoformans is inhaled from the environment, disseminate via bloodstream, and crosses the blood brain barrier (BBB) to cause cryptococcal meningoencephalitis (CM). Although CM causes significant mortality in HIV/AIDS patients, …

Machine Learning Analysis To Characterize Phase Variations In Laser Propagation Through Deep Turbulence, Luis Fernando Rodriguez Sanchez

Open Access Theses & Dissertations

The present Dissertation is focused on the analysis of the atmospheric conditions of a turbulent environmental system and its effects on the diffraction of a laser beam that moves through it. The study is based on the optical communication of two labs placed at the summit of two mountains located in Maui, Hawaii. The emitter system is located at the Mauna Loa mountain and the receiver at the Haleakala. The distance between both mountains is 150 km. The emitter system is at a height of 3.1 km and the receiver at 3.4 km. The maritime environment at the location experiences …

Investigation Of Iron Doped Gallium Oxide (Ga-Fe-O) System: Structure Property Relationship And Performance Evaluation For Optical And Catalytic Applications, Swadipta Roy

Open Access Theses & Dissertations

From September 2012 to May 2015, a phenocam monitored the seaward edge of a protected mangrove forest. Calculated GCC revealed seasonal greening patterns of a mangrove species, Rhizophoa apiculata, and an overall increase in the GCC, suggesting mangrove expansion. In comparing temperature and precipitation effects, it was found that this particular mangrove species had a greening optima at temperatures between 28°C and 28.5°C, and greening and canopy development response lag time of 10 weeks in response to precipitation. Tree saplings were monitored and showed to grow by 50%, mostly during a three month period during the rainy season. The establishment …

Photovoltage Enhancement For Stable Perovskite Solar Cells With A Temperature-Controlled Grain Growth Technique, Luis Eduardo Valerio

Open Access Theses & Dissertations

By performing strong characterizations methods, one can begin to fully understand the chemistry and composition behind a great performing perovskite solar cell. Understanding how the interaction between layers inside a solar cell is driven by the temperature and overall environment is a key element to improve the fabrication process and overall efficiency of such cells. This Thesis will present a study of the hybrid organic-inorganic, mixed-cation, mixed-halide, temperature and thickness-controlled perovskite solar cell. A constant power conversion efficiency (PCE) ranging between 15-17% and an open circuit voltage V¬oc above 1.05 V for a wide-band gap perovskite cell is presented.

Design Of A Linerless Cryogenic Propellant Tank For A Small Payload Launch Vehicle, Itzel Adriana Torres

Open Access Theses & Dissertations

The need of lightweight launch vehicles that will reduce the cost and make flights more frequent into orbit has called for an increase of composite materials in the aerospace industry. Composite material’s low thermal conductivity, high resistance to fatigue, and most importantly, low-weight can greatly reduce the cost of launch operations by decreasing the overall weight of the vehicle. Weight and cost savings are critical because any amount of weight that is saved can be directly applied as an additional amount of payload capability. The tanks on space vehicles are pressurized vessels that store fuel at cryogenic temperatures and have …

Synthesis And Advanced Manufacturing Of Polymer Structures And Their Composites, Bethany Rose Wilburn

Open Access Theses & Dissertations

The following research work performed embodies three unique studies of polymer structures and their composites. In general, polymers are viscoelastic, insulative materials that are used for a wide variety of applications within industrial, aerospace, and biomedical fields. Polymers have been studied and optimized for any particular use by chemically synthesizing unique micro-structures, altering the physical properties through fabrication and post-processing, and utilizing 3D printing to achieve complex geometries. In the past decade, additive manufacturing (AM) has drawn extensive attention across academia, industry, and government agencies. It offers unprecedented advantages such as design freedom, rapid prototyping, and customization. In this work, …

Additive Manufacturing Of Engineered Material Systems For Energy Applications, Luis Angel Chavez

Open Access Theses & Dissertations

Despite increasing efforts to use renewable electricity generation techniques in the last couple of decades, the world is still heavily reliant on traditional power generation techniques. This creates the need to make such systems cheaper and less pollutant through improvements to their efficiency. Increasing the efficiency and reliability of energy conversion systems, specially those based on combustion processes has been of interest for many years. However, material limitations have brought these systems to a stagnant condition.

A novel approach to help increase the efficiency of such systems is to closely monitor their operating conditions and therefore be able to increase …

A Probabilistic Creep Constitutive Model For Creep Deformation, Damage, And Rupture, Md Abir Hossain

Open Access Theses & Dissertations

The structural analysis of Industrial Gas Turbine (IGT), Aeroengine, Gen IV nuclear components under in-service conditions at various stress and temperature are susceptible to time-dependent creep deformation and creep induced failure. Such failure phenomena are exacerbated by the randomness in material properties, oscillating loading conditions, and other sources of uncertainty. The demand for physically based probabilistic creep modeling is highly sought by alloy designers. The objective of this study is to develop and validate a probabilistic creep-damage model incorporating multi-sources of uncertainty to replace the traditional deterministic and empirical decision-based modeling. In this study, the deterministic Sine-hyperbolic (Sinh) creep-damage model …