Engineering Commons^™

Experimental Investigation Of Cryogenic Convection And Boiling In Traditionally And Additively Manufactured Rocket Engine Cooling Channels, Armando Sandoval

Open Access Theses & Dissertations

The Center for Space Exploration and Technology Research at the University of Texas at El Paso, has designed, built, and optimized an experimental high heat flux test facility to investigate the heat transfer coefficient of liquid methane and other cryogenic propellants for regenerative cooled rocket engine design. The system is composed of a copper conduction based thermal concentrator that delivers heat flow into a single sub-scaled cooling channel (test article). This study focuses on optimizing this design of the high heat flux test facility to develop a more accurate method for measuring the conductive heat flow going into the cooling …

Design & Analysis Of A 500 Lbf Liquid Oxygen And Liquid Methane Rocket Engine, Daniel Eduardo Vargas

Open Access Theses & Dissertations

The rapid growth in demand for spacecraft technologies has spawned a need for a variety of new and innovative research. The utilization of liquid oxygen (LOX) and liquid methane (LCH4) in rocket engines have played an important role in space exploration efforts to promote missions to Mars with in-situ resource utilization for propellant production. This will allow the production of fuel needed to come back to Earth making the overall mission more cost effective by enabling larger usable mass.

The Center for Space Exploration and Technology Research has focused its efforts to developing Liquid Oxygen (LOX) and Liquid Methane (LCH4) …

Material Behavior Of Window 7 Carrier Panel Tiles And Thermal Pane Fragments Recovered From The Space Shuttle Columbia, Brenda Roseanne Arellano

Open Access Theses & Dissertations

Since the end of the space shuttle program, a new generation spacecraft has been developed to transport humans back into space. NASAâ??s Orion will carry a crew beyond low-earth orbit and the exploration of Mars may be possible in the future. Space safety becomes significant with human spaceflight and the risks are high. However, aerospace materials may provide opportunities to prevent future disasters. When the space shuttle Columbia disintegrated during re-entry in 2001, thousands of debris were collected for analysis. In contrast, when the Challenger space shuttle broke apart in 1986, all shuttle debris were buried. These tragic disasters are …

Label-Free Raman Imaging To Monitor Breast Tumor Signatures, John Ciubuc

Open Access Theses & Dissertations

Methods built on Raman spectroscopy have shown major potential in describing and discriminating between malignant and benign specimens. Accurate, real-time medical diagnosis benefits in substantial improvements through this vibrational optical method. Not only is acquisition of data possible in milliseconds and analysis in minutes, Raman allows concurrent detection and monitoring of all biological components. Besides validating a significant Raman signature distinction between non-tumorigenic (MCF-10A) and tumorigenic (MCF-7) breast epithelial cells, this study reveals a label-free method to assess overexpression of epidermal growth factor receptors (EGFR) in tumor cells. EGFR overexpression sires Raman features associated with phosphorylated threonine and serine, and …

The Interplay Between Grain Size And Austenite Stability On Deformation Behavior Of High Strength-High Ductility Combination Nanostructured Stainless Steel, Venkata Sai Ananth Challa

Open Access Theses & Dissertations

The concept of phase reversion involving severe cold deformation of metastable austenite to generate strain-induced martensite, followed by temperature-time 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 â??high strength-high ductilityâ?? combination in nano/ultrafine-grained (NG/UFG) austenitic stainless steel. Using this concept, the objective of the study is to elucidate the dependence of grain size on deformation mechanisms and deformation-induced microstructural changes. The objective was accomplished by combining depth-sensing nanoindentation experiments conducted at various strain rates, and interrupted tensile testing at various strain and post-mortem analyses of deformed …

Dft Study Of Adsorption Of Trimetallic Endohedral Fullerenes On Graphene, Nakul Nitin Karle

Open Access Theses & Dissertations

A density functional theory (DFT) study on the geometric and electronic structure of C60 and Sc3N@C80 along with their adsorption on pristine single layer graphene (SLG) is presented. C60 is found to adsorb in two nearly degenerate configurations: (i) with a pentagon facing the SLG, which is the most stable one, and (ii) with a hexagon facing the SLG in a face-to-face perfect alignment, rarely common in Ï?â??Ï? interactions, 0.06 eV higher in energy. The calculated binding energy of 0.76 eV, which includes dispersion effects, is in good agreement with previous theoretical and experimental reports. On the contrary, Sc3N@C80 adsorption …

Design And Development Of A Foil Application Tool For A Foil Embedding Process In The Multi3d Manufacturing System, Betty Elizabeth Mckenzie

Open Access Theses & Dissertations

Additive manufacturing (AM) encompasses different technologies, including material extrusion 3D printing, a technology commonly referred to as fused deposition modeling (FDM), which is the focus of the work described in this manuscript. Additive manufacturing is a growing technology with many applications in numerous fields from the air force to medical offices. FDM is a process that uses thermoplastics, in this case polycarbonate (PC), where the PC is heated and selectively dispensed in a layer-by-layer process to create a 3D printed part. Currently, FDM systems have advantages over subtractive manufacturing or machining because cavities and other components (e.g., microchips, valves, and …

Production And Functionality Of Melanocytes For Use In 3d-Printed Pigment-Capable Skin Tissue, Corinne Nicole Wittmann

Open Access Theses & Dissertations

Skin grafts are used in a variety of medical procedures including burn treatment, skin cancer removal, chronic wound/ulcer treatment, skin infections and diseases, large wound closure and in elective plastic surgeries. Ideally, skin grafts are harvested directly from the patient. However, in some cases, direct harvesting of skin grafts is not possible. In these situations, an equivalent skin substitute obtained through another source is utilized. There will always be a greater risk of rejection in such cases and therefore is only intended to be a temporary treatment. A possible solution to lessen the risks and issues associated with skin grafts …

Microstructure And Mechanical Properties Of Sputter-Deposited Nanocrystalline W1-Ymoyo3 Thin Films, Gabriel Lopez

Open Access Theses & Dissertations

Currently, there is a wide-spread interest in the design and development of indium (In) free transparent conductive oxides (TCOs) for utilization in photovoltaics and optoelectronics. Tungsten oxide (WO3)-based materials are being explored for their utilization in solar cells, photo-electrochemical cells (PECs), electrochromic (EC) "smart windows," information displays, variable reflectance mirrors, and photo-detector materials. Designing ternary compounds or composite/hybrid structures coupled with tailoring the nano-architectures of WO3-based materials has been considered to be attractive develop potential candidates with enhanced performance. In this context, in this Thesis work, an attempt is made to prepare W-Mo-O nanocomposite films, which can be considered as …

Supplier Evaluation And Selection In Automotive Industry Using Conditional Probability, Anand Raj

Open Access Theses & Dissertations

Supplier evaluation and selection is one very important factor for the success of a company. There are many supplier evaluation and selection tools and software available in the market. But this approach is different from the others. Here a comprehensive list of suppliers selection criteria is selected and they are divided in 3 supplier selection group. This group of criteria is done based on the relationship among them. All the suppliers are evaluated based on these 3 supplier selection group. The supplier with the highest value is selected. The probability associated with that factor is assigned and at the end …

Influence Of Overlay Thickness On Interface Bonding, Aliasghar Dormohammadi

Open Access Theses & Dissertations

Overlaying is an efficient and proven pavement preservation approach for flexible pavements. The overlay thickness varies from 1 in. to 4 in. depending on the conditions of the existing pavement, financial resources, etc. In the recent decade, financial constraints in conjunction with the push for pavement preservation, the overlay thickness is being reduced to less than an in. The ultra-thin overlay is a new cost-effective method that can be used to preserve functional pavement problems and provide satisfactory ride quality. Although studies have been conducted to evaluate pavement systems using numerical simulation, the research in the area of evaluating existing …

Molecular Dynamics Studies Of Crystal Growth Phenomena In Cdte Based Heterostructures, Rodolfo Aguirre Ii

Open Access Theses & Dissertations

Cadmium telluride (CdTe) is a material used to make solar cells because it absorbs the sunlight very efficiently and converts it into electricity. However, CdTe modules suffer from degradation of 1% over a period of 1 year. Improvements on the efficiency and stability can be achieved by designing better materials at the atomic scale. Experimental techniques to study materials at the atomic scale, such as Atomic Probe Tomography (APT) and Transmission Electron Microscope (TEM) are expensive and time consuming. On the other hand, Molecular Dynamics (MD) offers an inexpensive and fast computer simulation technique to study the growth evolution of …

Development And Verification Of A Lab-Scale Green Propellant Hybrid Motor System, Shyamal Patel

Open Access Theses & Dissertations

Hybrid rocket propulsion offers the potential to combine advantages of both solid and liquid propellant systems, but low regression rates hinder their practicality. The suggested use of hydroxylammonium nitrate (HAN) based propellants in hybrids offers the potential for developing high impulse motors with low development and production costs. In this paper, I present the development of a small-scale system used to measure the regression rate of a hybrid motor. The system can accommodate fuel grains 5 cm long with an outer diameter of 6 cm and can implement the various decomposition gases needed for HAN. The motor firings of hydroxyl …

Development And Integration Of The Janus Robotic Lander: A Liquid Oxygen - Liquid Methane Propulsion System Testbed, Raul Ponce

Open Access Theses & Dissertations

Initiatives have emerged with the goal of sending humans to other places in our solar system. New technologies are being developed that will allow for more efficient space systems to transport future astronauts. One of those technologies is the implementation of propulsion systems that use liquid oxygen and liquid methane (LO2-LCH4) as propellants.

The benefits of a LO2-LCH4 propulsion system are plenty. One of the main advantages is the possibility of manufacturing the propellants at the destination body. A space vehicle which relies solely on liquid oxygen and liquid methane for its main propulsion and reaction control engines is necessary …

Design Of A Feed System For An Oxy-Methane High Pressure Combustor, Jorge Arturo Rosero

Open Access Theses & Dissertations

With growing concern over the effects that fossil fuels are having on the environment and the expected increases in energy demand in the coming decades, it is becoming increasingly more important to find cleaner and more efficient ways to generate energy. Natural gas has grown in popularity in the last decade thanks to a drastic drop in price and its lower carbon emissions compared to coal. With enough natural gas reserves in the United States to last over 90 years, natural gas is expected to be a large part of the future energy outlook.

Increased demand from growing populations also …

Evaluation Of Mechanical Parameters Of Contaminated Road Base And Railway Ballast, Prajwol Tamrakar

Open Access Theses & Dissertations

This Dissertation comprises two topics in the area of transportation geotechnics that focus on the evaluation of stiffness parameters of contaminated road base and railway ballast. The abstracts of these two studies are provided in the following two paragraphs.

The performance of a flexible pavement depends on the mechanical characteristics of its unbound granular base layer. The mechanical characteristics such as stiffness and deformation resistance depend on many factors such as the material gradation, fines content, moisture content, physical properties of coarse aggregate and more. The base materials are often contaminated by the excessive fines that is caused by improper …

Process-Structure-Property Relationship In Magnesium-Based Biodegradable Alloy For Biomedical Applications, Pramanshu Trivedi

Open Access Theses & Dissertations

Magnesium alloys are considered to be the next generation of biomaterials because of their ability to degrade in the physiological environment. We elucidate here the impact of multiaxial forging of Mg-2Zn-2Gd alloy on grain refinement to sub-micron regime and relate the structure to mechanical properties and biological functionality. As-cast and annealed samples were multiaxial forged (MAF) for a total number of two passes with a true strain of ~2/pass. Considering that the microstructure governs the biological response of materials, we studied the constituents of the microstructure in conjunction with the mechanical behavior. The antimicrobial behavior in a Mg-2Zn-2Gd alloy with …

Improving The Regression Rate Of An Htpb Hybrid Rocket Fuel Grain, Travis Wesley Belcher

Open Access Theses & Dissertations

Hybrid rockets are the combination of liquid and solid propellant systems. The University of Texas at El Paso (UTEP) is currently researching combining Hydroxyl-Terminated Polybutadiene (HTPB) and Hydroxyl Ammonium Nitrate (HAN) in preparation for conducting testing using an Air Force developed monopropellant known as AF-M315E as an oxidizer. A new system was developed to conduct this testing based in the Goddard Laboratory at UTEP. This system was subjected to a series of tests to ascertain its performance characteristics, which are detailed in this Thesis.

Characterization Of Electrically Conductive Inks In Simulated Space Environment, Kazi Md Masum Billah

Open Access Theses & Dissertations

Increasing numbers of satellite missions necessitate a standalone power supply with self-recovery capabilities in case of failure in the space environment. A self-repairing kit was developed with the capabilities to repair the damaged solar array by dispensing conductive inks. Dispensing of conductive materials using direct writing technology to the space environment not only repairs damaged electronic components but also demonstrates the possibilities of manufacturing in outer space. For earth application, properties of direct writing inks have been evolved. In space application, direct writing inks or conductive inks have some issues such as outgassing, vapor pressure, curing etc.Therefore, having the properties …

Electronic Structure Studies On Transition Metal Containing Endohedral Fullerenes, Carbon Onions And Zinc Sulfide Cages, Shusil Bhusal

Open Access Theses & Dissertations

We present the most stable structures for VXSc3-XN@C2n (where X=1-3 and 2n=70, 76, 78 and 80) using a systematic procedure that involves all possible isomers of the host fullerene cages. Subsequently, a detailed investigation of structural and electronic properties of the lowest energy isomers is performed using density functional theory in combination with large polarized Gaussian basis sets. The search procedure developed involved structural optimizations of thousands of fullerenes and correctly identifies the experimentally observed VSc2N@C80 and V2ScN@C80 isomer as the most stable structures. The structural analysis shows that a few V-doped endohedral fullerenes do not follow the isolated pentagon …

Theoretical Acoustic Absorber Design Approach For Lox/Lch4 Pintle Injector Rocket Engines, Jonathan Candelaria

Open Access Theses & Dissertations

Liquid rocket engines, or LREs, have served a key role in space exploration efforts. One current effort involves the utilization of liquid oxygen (LOX) and liquid methane (LCH4) LREs to explore Mars with in-situ resource utilization for propellant production. This on-site production of propellant will allow for greater payload allocation instead of fuel to travel to the Mars surface, and refueling of propellants to travel back to Earth. More useable mass yields a greater benefit to cost ratio. The University of Texas at El Paso's (UTEP) Center for Space Exploration and Technology Research Center (cSETR) aims to further advance these …

Organic-Inorganic Graphite And Transition Metal Dichalcogenide Based Composites For 3d Printing, Jorge Alfredo Catalan Gonzalez

Open Access Theses & Dissertations

This project was multipronged to help fuse together topics of additive manufacturing and two-dimensional (2D) layered materials, and studying the mechanical and electrical properties of the composites produced. The composites are made from the thermoplastic polymer acting as a matrix and the graphite and 2D transition metal dichalcogenides (TMDs) serving as the filler or reinforcement. Different concentrations of TMD's were added to the matrix to study the effect of composition on the mechanical and electrical properties. To shed insights into the mechanical properties, test coupons were produced as "dog bone" structures for tensile testing using the ASTM D638 type 5 …

Mechanically Activated Magnesiothermic Combustion Synthesis Of Zirconium And Hafnium Diborides, Sergio Cordova

Open Access Theses & Dissertations

Magnetohydrodynamic (MHD) generation of electric power has the potential to increase the thermal efficiency of fossil-fuel burning power plants. Electrode materials in MHD generators must possess a high melting point, high electrical and thermal conductivities, chemical stability, and resistance to thermal shock, oxidation, and plasma sparks/arcs. Ultra-high temperature ceramics based on diborides of zirconium and hafnium (ZrB2 and HfB2) are promising materials for this application. Self-propagating high-temperature synThesis (SHS) is an attractive method for their large-scale fabrication, but SHS of ZrB2 and HfB2 from elemental Zr, Hf, and B is not economically viable because of the high cost of the …

Design And Development Of A High Pressure Oxy-Methane Combustor, Jaime Cruz Gurrola

Open Access Theses & Dissertations

Most of the greenhouse gas emissions in the US comes from the electricity sector by burning fossil fuels. Environmental regulations have been implemented to reduce the amount of CO2 emitted into the atmosphere. One method to reduce the greenhouse gas emissions to the atmosphere is oxy-fuel technology. One of the biggest challenges of oxy-fuel combustion is thermal management due to the elevated temperature combustion. The main objective of this Thesis was to design and develop a steady-state high pressure combustor that uses oxygen and methane with a thermal power input of 500 kW and operation at 20 bar pressure. An …

Advances In Chemical Vapor Deposition Growth Of Molybdenum Disulfide For Photodetectors And Flexible Electronics, Carlos Francisco De Anda Orea

Open Access Theses & Dissertations

The conversion of light into electrical signals is at the basis of technologies that affect our daily lives. Applications, including video imaging, optical communications, biomedical imaging, security, night-vision, gas sensing and motion detection have reached a high level of maturity due to the development of high-performance materials, large-scale production, and integration technologies. Currently conventional photodetectors made of Silicon (Si) or III-V compounds are about to reach their maximum efficiency, and every time it is harder to get a noticeable improvement in performance of sensors based on these materials, not to mention the complicated fabrication methods to achieve just a few …

Methods For Producing Graphene From Petroleum By-Products, Eva M. Deemer

Open Access Theses & Dissertations

N/A

First Level Design And System Design Of Janus Liquid Oxygen-Liquid Methane Lander, Jahir Fernandez

Open Access Theses & Dissertations

Taking humans to space has always been a fantastic feat, but taking humans to another planet in our solar system is the new goal. Technology has come a long way and with that, so has our knowledge of space and what can be done with current technology to accomplish our goal. These technologies allow for a more efficient space system to transport future astronauts using liquid oxygen and liquid methane (LO2-LCH4) as propellants. This combination of propellants, LO2-LCH4, brings a variety of benefits. One of the main advantages is that they can be recovered or created from local resources, using …

Development Of Post-Pareto Optimality Methods For Multiple Objective Optimization, Juan Valentin Fernandez

Open Access Theses & Dissertations

In the past years, multiple objective optimization has been considered, as an important research area since in many real life problems there exists multiple criteria that need to be optimized simultaneously. The use of evolutionary algorithms or metaheuristic methods as solution methodologies lead to a large number of Pareto solutions rather than a single unique optimum. This Pareto-optimal set most of the time tends to be very large and the decision maker now faces the challenge of reducing its size to analyze a feasible number of solutions, thus deciding the best possible solution. In this work, two methods will be …

Behavior Of Sandwich Composite Cores Under Extreme Conditions, Carlos Daniel Garcia Perez

Open Access Theses & Dissertations

The use of composite structures for diverse applications have become of great interest for scientists and engineers thanks to the advantages that they may offer in comparison to conventional materials. In the case of sandwich composite structures, its mechanical properties can be tailored according to the necessities through the correct selection of a core and facesheets. In combination, this "new" material will have superior properties compared to traditional materials such as steel and aluminum. For arctic exploration, a core with low moisture absorption, low density, and resistance to extreme, low temperatures is desirable for this type of application. This Thesis …

Test Methods For The Fracture And Fatigue Crack Growth Behavior Of Hot Mix Asphalts, Eduardo Garcia

Open Access Theses & Dissertations

The service life and mechanical properties of bituminous mixtures are greatly affected by distress problems such as fracture, thermal cracking, and fatigue cracking of the asphalt layers. The fracture and fatigue crack growth (FCG) behavior of bituminous mixtures are difficult to quantify due to material-, test-, and equipment-related uncertainties. The goal of this study is to introduce a systematic fracture and fatigue crack growth testing approach for hot mix asphalts (HMAs). The objective is to experimentally evaluate the fracture resistance and fracture toughness behavior of a dense-graded HMA material at different temperatures and varying thicknesses. The effect of thickness on …