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Articles 1 - 24 of 24
Full-Text Articles in Mechanical Engineering
Evaluation And Implementation Of Lean Engineering Principles For Improving A University Rocket Team, Alan Garcia
Evaluation And Implementation Of Lean Engineering Principles For Improving A University Rocket Team, Alan Garcia
Open Access Theses & Dissertations
In the present day, lean is a tool applied to manufacturing industries trying to reduce wasteand non-value-added work to every process during the supply chain. While implementing lean thinking in the industry has been highly effective, it is less common for academic purposes. However, it can also improve performance if the concept is correctly applied. The purpose of this thesis is to show and analyze the application of Lean Engineering thinking and its six principles to the Sun City Summit Rocket Team from the University of Texas at El Paso which competed in the Intercollegiate Rocket Engineering Competition (IREC) Spaceport …
Fabrication And Characterization Of Germanium Functionalized Porous Nickel Oxide Electrodes For Application In Supercapacitors, Cristina Gonzalez
Fabrication And Characterization Of Germanium Functionalized Porous Nickel Oxide Electrodes For Application In Supercapacitors, Cristina Gonzalez
Open Access Theses & Dissertations
Limited fossil fuel, increasing population, pollution, and climate change are motivating society to use renewable and clean energy techniques. However, the intermittent nature of renewable sources hinders their continuous availability and use. Energy storage devices such as supercapacitors and batteries are essential for sustainable development but their high cost limits its bulk use. The cost of energy storage devices mainly depends on materials, synthesis process and device fabrication. Therefore, low cost 3-D mesoporous nickel germanium fictionalize nickel oxides electrode materials has been developed by using facile fabrication techniques for supercapacitor application. 3-D mesoporous nickel provides the high surface area and …
The Qualification Of Sealability And Creep Relaxation Of Additively Manufactured Zytel Gaskets For Pem Fuel Cells, Robert Lazarin
The Qualification Of Sealability And Creep Relaxation Of Additively Manufactured Zytel Gaskets For Pem Fuel Cells, Robert Lazarin
Open Access Theses & Dissertations
The purpose of this thesis is to study the feasibility of low-cost additive manufacturing of gaskets for proton exchange membrane fuel cells exposed to extreme temperature conditions ranging from -55°C to 100°C. With the growing popularity and decreasing costs of additive manufacturing technologies, specifically Material Extrusion (ME), research is being conducted to determine the feasibility of ME components. Thermally cycled PEMFCs may exhibit accelerated gasket deterioration, therefore, the mechanical stability of material extruded gaskets following a harsh thermal cycle must be assessed. The feasibility of the material extruded gaskets will be proven by manufacturing optimization and mechanical testing. The target …
Synthetic Data Generation For Intelligent Inspection Of Structural Environments, Noshin Habib
Synthetic Data Generation For Intelligent Inspection Of Structural Environments, Noshin Habib
Open Access Theses & Dissertations
Automated detection of cracks and corrosion in pavements and industrial settings is essential to a cost-effective approach to maintenance. Deep learning has paved the path for vast levels of improvement in the area. Such models require a plethora of data with accurate ground truth and enough variation for the model to generalize to the data, which is notwidely available. There has been recent progress in computer graphics being used for the creation of synthetic data to address the issue of deficient data availability, but it is limited to specific objects, such as cars and human beings. Textures and deformities within …
Cad-Based Aerial Trajectory Generation And 3d Mapping For Close-Quarter Inspection, Angel Guillermo Ortega Castillo
Cad-Based Aerial Trajectory Generation And 3d Mapping For Close-Quarter Inspection, Angel Guillermo Ortega Castillo
Open Access Theses & Dissertations
Robotic technologies for inspection purposes of large-scale structures have grown in interest.Such technologies are encouraged to reduce the risk in which human operators are involved and to reduce costs due to downtime of the equipment. In the Energy sector, high interest is placed on power plant components where their correct operation is paramount. This work is inspired by the synthetic vision systems for aerial vehicles that use three-dimensional space (3D) to provide pilots with clear and intuitive means of understanding their flying environment. This work can be separated into three main sections: Trajectory Generation from Computer-Aided Design (CAD) Models, Crack …
Fabrication And Characterization Of Iron-Based Catalysts For The Dehydrogenation Of Fossil Fuels, Victoria Isabel Reyes
Fabrication And Characterization Of Iron-Based Catalysts For The Dehydrogenation Of Fossil Fuels, Victoria Isabel Reyes
Open Access Theses & Dissertations
For a prosperous and sustainable future, hydrogen is an encouraging solution due to its simple transition for industrial decarbonization and synergy for economic development. Paradoxically, current hydrogen production pathways release substantial amount of greenhouse gases into the atmosphere contributing to climate change. To keep up with increasing demand, hydrogen could be produced through microwave-assisted thermocatalytic dehydrogenation of fossil fuels without emitting carbon dioxide. This requires specified catalysts to meet the requirements of hydrogen yield and selectivity. The objective of the present research is to fabricate, characterize, and compare iron-based alumina (FeAl_x O_y) catalysts produced via solution combustion synthesis and iron-based …
Compact Electrospray Propulsion Systems For Small Form-Factor Satellites: An Orbital Performance Survey & Platform Design, Alberto Meza
Compact Electrospray Propulsion Systems For Small Form-Factor Satellites: An Orbital Performance Survey & Platform Design, Alberto Meza
Open Access Theses & Dissertations
Over the past decades, small form-factor satellites such as CubeSats have remained as one of the most accessible platforms to reach space for universities, research institutions, private and governmental entities to perform a wide range of missions. This paper presents a survey into the design and implementation of an electrospray rail thruster, to be integrated to the CubeSat platform. The design investigated features propellant tanks for each individual thruster embedded inside the rail of a standard 1U CubeSat. The capabilities of utilizing the electrospray thruster as an attitude & determination control system was also investigated in which, a pointing accuracy …
Direct Ink Write And Thermomechanical Characterization Of Thermoset Composites, Sergio Dante Favela
Direct Ink Write And Thermomechanical Characterization Of Thermoset Composites, Sergio Dante Favela
Open Access Theses & Dissertations
This research will be divided into two sections. The first section discusses direct ink writing and thermomechanical characterization for thermoset composites. The thermoset ink is prepared with fillers aiding the printing process by modifying the rheology of the ink and geometry retention by allowing for the part to have an initial UV cure step. Three specimen formulations with different weight percentages were printed by material extrusion in the shape of tensile specimens following ASTM standard D638 to characterize the mechanical properties at room temperature, 100â?? and 200â??. Furthermore, the ink resin was characterized through DSC, TGA, and rheology testing. The …
Fabrication, Microstructure And Mechanical Characterization Of Crvnbtaw High Entropy Alloy Coatings Using Magnetron Sputtering, Jorge Quezada
Fabrication, Microstructure And Mechanical Characterization Of Crvnbtaw High Entropy Alloy Coatings Using Magnetron Sputtering, Jorge Quezada
Open Access Theses & Dissertations
In this project a CrVNbTaW high entropy alloy was evaluated. The samples were made using radio frequency magnetron sputtering and were made under similar conditions. The deposition parameters were explored to find the ideal deposition process. The process included a pressure from 0.1-2mTorr, 600C, 1 hour duration, at 100W power to guns, and constant argon flow. The samples were fabricated under similar parameters using silicon steel and sapphire substrates. The samples were analyzed and characterized using X-ray diffraction, scanning electron microscopy, atomic force microscopy, nanoindentation and corrosion testing. Based on these results we were able to get a better understanding …
Cryogenic Flow Boiling Heat Transfer On Additively Manufactured Liquid Rocket Engine Cooling Channels, Debra Jazmin Ortega
Cryogenic Flow Boiling Heat Transfer On Additively Manufactured Liquid Rocket Engine Cooling Channels, Debra Jazmin Ortega
Open Access Theses & Dissertations
The enhancement of flow boiling heat transfer is critical because it can solve thermal management issues seen across all engineering and manufacturing applications. Even though advancements are being made, more studies are needed to understand the behavior of forced convective boiling further.Currently, there are four major issues in the field of regenerative cooling of liquid rocket engines. 1. The cooling channels are typically manufactured using conventional machining, while aerospace industries are currently exploring the additive manufacturing approach. 2. The experimental critical heat flux values for cryogenic fluids are either lower or very close to the model predictions; however, the effect …
Novel Interlaminar Reinforcement To Enhance The Impact Damage Resistance Of Carbon Fiber-Reinforced Polymer Matrix Composites, Daisy Haidee Mariscal
Novel Interlaminar Reinforcement To Enhance The Impact Damage Resistance Of Carbon Fiber-Reinforced Polymer Matrix Composites, Daisy Haidee Mariscal
Open Access Theses & Dissertations
Aerospace, aircraft, marine, and automobile applications are increasingly using composite materials for lighter, higher stiffness, and strength properties. Despite these advantages, composite materials have one major disadvantage. The through-thickness properties are extremely weak when subjected to impact damage. When a composite material is subjected to a low-velocity impact, there is hardly any visible damage on the surface compromising the composite material internally without any external notice. Internal damage may be delamination, which is the most common, matrix cracking, and fiber breakage. A composite material is made up of layers of fiber. The interlaminar region is located in between these layers. …
High-Temperature Valve Design For A Solid Oxide Fuel Cell/Gas Turbine Hybrid System Utilizing Smart Materials, Alba Jazmin Leyva
High-Temperature Valve Design For A Solid Oxide Fuel Cell/Gas Turbine Hybrid System Utilizing Smart Materials, Alba Jazmin Leyva
Open Access Theses & Dissertations
The topic of this project includes extensive research on the Solid Oxide Fuel Cell Gas Turbine (SOFC/GT) hybrid system located at the National Energy Technology Laboratory. The goal is to reduce pollution and generate energy by using natural gas and a combination of fuel cells, heat exchangers, bypass valves, turbines, and combustors as components working together to produce clean energy. The SOFC/GT system works by having the fuel cell pressurized by the gas turbine. The turbine then produces exhaust gas for the fuel cell, because the turbine recovers the majority of the heat and the pressurization contributes to the enhancement …
Multi-Sensor Signatures From Ultrasonic Wire Embedding Used In Hybrid Additive Manufacturing, Patrick Steven Gutierrez
Multi-Sensor Signatures From Ultrasonic Wire Embedding Used In Hybrid Additive Manufacturing, Patrick Steven Gutierrez
Open Access Theses & Dissertations
Additive Manufacturing (AM) has matured such that its products are used in applications ranging from prototypes to end-use parts; however, to expand the adoption of AM, the inclusion of multiple manufacturing technologies has become a focus area especially when the result is a 3D printed part with an embedded electrical system. The W.M. Keck Center for 3D Innovation has developed the Foundry Multi3D system consisting of two material extrusion AM machines, a robotic arm, and a CNC machine equipped with a laser soldering tool, solder micro-dispensing tool and an ultrasonic wire embedding (USWE) tool. The focus of this paper is …
Characterization Of 3d Printed Parts Containing Integrated Functionality Via Ultrasonically Embedded Wires, David Abraham Sepulveda
Characterization Of 3d Printed Parts Containing Integrated Functionality Via Ultrasonically Embedded Wires, David Abraham Sepulveda
Open Access Theses & Dissertations
Material extrusion additive manufacturing has been widely adopted because it offers freedom of design, which allows complex geometry fabrication, and rapid prototyping. Interest in producing components with integrated functionality allowed forms of hybrid manufacturing to be developed such as the Multi3D system. This system produces parts with embedded components by combining additive, subtractive, soldering, dispensing, and embedding techniques. However, this involves pausing the printing process (which takes place in a controlled environment) and exposing it to ambient temperature where embedding takes places. In this research, the effect of embedding parts with 24 AWG copper for improved functionality was quantified mechanically. …
Optimization Of Lattice Structure Using Machine Learning Approach, Tanzila Bint Minhaj
Optimization Of Lattice Structure Using Machine Learning Approach, Tanzila Bint Minhaj
Open Access Theses & Dissertations
The goal line of designing any structure is to get maximum performance at minimum cost. Therefore, optimization is the only method to achieve that objective. Engineers have been practicing different formats of optimization. Topological optimization is one of the well-known long-practiced methods. But it is always desired to find the most helpful design method that considers every relevant parameter associated with the structure. In the continuation of this search to enhance the efficacy of design through optimization, a new approach was explored in the following work. The motivation was to enable a model to be capable of finding out the …
Thin Film Evaporation Through Engineered Copper Micropillar Arrays, Alejandro Amador
Thin Film Evaporation Through Engineered Copper Micropillar Arrays, Alejandro Amador
Open Access Theses & Dissertations
This work explored and characterized the evaporator section of a fully engineered heat pipe, a proposed semi-passive cooling solution for the thermal management at high heat fluxes, with the use of thin film evaporation. High heat loads present a problem in electronics, circuitry, space, and defense applications which are the main target areas for this cooling solution. Conventionally manufactured flat samples made of copper micropillar arrays were tested to determine their heat removal capabilities for high heat flux applications. The samples were manufactured with 400 μm micropillar hydraulic diameter, various micropillar spacings ranging from 500-1100 μm, with 500 μm and …
Characterization Of A Flex-Fuel Oxy-Combustion System Through Experimental Investigation And Computational Modeling, Md Mohieminul I. Khan
Characterization Of A Flex-Fuel Oxy-Combustion System Through Experimental Investigation And Computational Modeling, Md Mohieminul I. Khan
Open Access Theses & Dissertations
Oxy-fuel combustion has the potential to offer high thermal efficiency and lower pollutants emission compared to other existing combustion technologies. More than 63% of the worldâ??s electricity is produced by fossil fuel combustion which also is the major reason for greenhouse gas emissions. Oxy combustion offers a solution to it. Oxy combustion uses pure oxygen as an oxidizer instead of air which eliminates the NOx and SOx products from the exhaust. In oxy-combustion flue gas mainly consists of CO2 and water vapor. Furthermore, combustion in presence of pure oxygen results in higher flame temperature and hence promises higher thermal efficiency. …
Material Synthesis And Additive Manufacturing Of Ceramics, Elsa Bramasco-Rivera
Material Synthesis And Additive Manufacturing Of Ceramics, Elsa Bramasco-Rivera
Open Access Theses & Dissertations
This research is divided into two main topics: vitrimer polymers and alumina ceramics. Additive manufacturing is an emerging technology. In this research, two main methods of additive manufacturing are used: material extrusion and vat photopolymerization. The hypothesis of self-healing and mechanochromism functionalities was tested through the synthesis of vitrimers, a novel material combining properties of both thermosets and thermoplastics. These vitrimers were 3D printed using material extrusion. Casted vitrimers showed stiffening effects after submergence in water. Lithography based ceramics have gained attention in recent years due to their wide range of applications. Alumina ceramics were additively manufactured using digital light …
Application Of The Continuum Damage Mechanics Wilshire-Cano-Stewart (Wcs) Model, Jaime Aaron Cano
Application Of The Continuum Damage Mechanics Wilshire-Cano-Stewart (Wcs) Model, Jaime Aaron Cano
Open Access Theses & Dissertations
In this study, the applications of the continuum damage mechanics-based Wilshire-Cano-Stewart (WCS) model are explored to predict rupture time, minimum-creep-strain-rate (MCSR), damage, damage evolution, and creep deformation. Increase knowledge in manufacturing methods has pushed the limit of material science and the development of new materials. Conventional testing is required to qualify materials against creep which according to the ASME B&PV III code, 10,000+ hours of experiments are necessary for each heat before materials are put into service. This process is costly and not feasible for new materials. As an alternative, models have been employed to predict creep behaviors and reduce …
A Central Compact Hybrid-Variable Method With Spectral-Like Resolution, Md Mahmudul Hasan
A Central Compact Hybrid-Variable Method With Spectral-Like Resolution, Md Mahmudul Hasan
Open Access Theses & Dissertations
Numerical methods for hyperbolic conservation laws have been a driving force for theresearch in scientific computing and simulation science in the past decades, as many physical, biological, and engineering systems are governed by these equations, such as fluid mechanics, tumor growth, and virtual wind tunnel simulations. Despite the existence of many schemes in the literature, people have never stopped searching for more accurate and efficient methods for these problems. Indeed, the increasing complexity of systems in emerging applications demands better resolution of sub-grid scale phenomenon whereas classical methods usually fail to deliver high-fidelity simulation results of such systems within realistic …
Material Synthesis And Machine Learning For Additive Manufacturing, Jaime Eduardo Regis
Material Synthesis And Machine Learning For Additive Manufacturing, Jaime Eduardo Regis
Open Access Theses & Dissertations
The goal of this research was to address three key challenges in additive manufacturing (AM), the need for feedstock material, minimal end-use fabrication from lack of functionality in commercially available materials, and the need for qualification and property prediction in printed structures. The near ultraviolet-light assisted green reduction of graphene oxide through L-ascorbic acid was studied with to address the issue of low part strength in additively manufactured parts by providing a functional filler that can strengthen the polymer matrix. The synthesis of self-healing epoxy vitrimers was done to adapt high strength materials with recyclable properties for compatibility with AM …
Suitability Of Low-Cost Additive Manufacturing For Polymer Electrolyte Fuel Cells, David Alexander
Suitability Of Low-Cost Additive Manufacturing For Polymer Electrolyte Fuel Cells, David Alexander
Open Access Theses & Dissertations
The purpose of this dissertation is to study the feasibility of low-cost additive manufacturing to fabricate polymer electrolyte fuel cell bipolar plate materials. Traditional manufacturing techniques include molding, milling, hollow embossing, hydro-forming, rolling, and electromagnetic forming. These processes are employed when a design has been selected due to higher costs at low volumes. The combination of high initial costs and bipolar plates being the most expensive component of the polymer electrolyte fuel cell creates incentive to mitigate this obstacle. The feasibility of low-cost additive manufactured bipolar plates will be proven by fabrication, post-processing, and characterization of printed test specimen. The …
All-In-One Multi3d System: Exploring Potential Of 5-Axis Material Extrusion Additive Manufacturing, Angel Vega
All-In-One Multi3d System: Exploring Potential Of 5-Axis Material Extrusion Additive Manufacturing, Angel Vega
Open Access Theses & Dissertations
Additive Manufacturing (AM) has experienced consistent growth since its inception across its seven process categories, especially Material Extrusion (MEX) with systems that can be seen in commercial and industrial settings. As MEX evolves, innovation can be traced in the growing variety of available process materials and new system capabilities leading to greater interest in the technology across various industries including automotive, aerospace and even nuclear weapons. This has created an increasing demand for end-use parts from MEX systems leading to more complex machines with additional Degrees of Freedom (DoF), specialized workflows, and expanded post processing that address the drawbacks of …
Femtosecond Laser Machining Of Drilled Holes In Silicon Nitride, Stephani Nevarez
Femtosecond Laser Machining Of Drilled Holes In Silicon Nitride, Stephani Nevarez
Open Access Theses & Dissertations
In this study, the laser drilling parameters of a Nd:YAG ultrashort pulsed laser are evaluated to produce zero taper through holes on silicon nitride ceramics. Manufacturing of ceramics is expensive and difficult because of the mechanical and thermal properties of ceramics, limiting applications. Additionally, the high level hardness of the ceramic can affect the ceramic and the manufacturing tool. There is a need to explore non-contact machining such as laser machining to expand the uses of ceramics in industry applications.In order to accomplish this goal, understanding of the physical mechanisms that occurs while laser ablation is needed. Furthermore, the minimum …