Engineering Commons^™

Design And Development Of The Portable Build Platform And Heated Travel Envelope For The Multi3d Manufacturing System, Steven Daniel Ambriz

Open Access Theses & Dissertations

The final product functionality of parts produced by Additive Manufacturing (AM) can, in part, be improved by the inclusion of multi-material capabilities. The “Multi3D system” that is under development at The University of Texas at El Paso uses material extrusion printing (or fused deposition modeling), solid conductor wire embedding, direct-write, component placement, and micromaching to enable multi-material fabrication. The Multi3D was designed to transport a workpiece between manufacturing stations via a six-axis robot, portable build platform (PBP), and a controlled temperature environment or chamber that travels to each manufacturing station. The heated travel envelope (HTE) was included to mitigate thermal …

Combustion Synthesis Of Molybdenum Silicides And Borosilicides For Ultrahigh-Temperature Structural Applications, Mohammad Shafiul Alam

Open Access Theses & Dissertations

Molybdenum silicides and borosilicides are promising structural materials for gas-turbine power plants. A major challenge, however, is to simultaneously achieve high oxidation resistance and acceptable mechanical properties at high temperatures. For example, molybdenum disilicide (MoSi₂) has excellent oxidation resistance and poor mechanical properties, while Mo-rich silicides such as Mo₅Si₃ (called T₁) have much better mechanical properties but poor oxidation resistance. One approach is based on the fabrication of MoSi₂−T₁ composites that combine high oxidation resistance of MoSi₂ and good mechanical properties of T₁. Another approach involves the …

Characterization Of W-Ti-O Thin Films For Application In Photovoltaics, Amanda Patricia Christmas

Open Access Theses & Dissertations

Photovoltaic (PV) devices consist of the conversion of light energy into electricity. Nearly all PV technologies employ transparent conducting oxides (TCO) as an integral part of the de-vice structure so that the light can reach the semiconductor. The predominant transparent conducting oxide (TCO) that is currently being used in industry is indium tin oxide (ITO). However, Indium (In) is high in cost and becoming scarce in the world. This work is focused towards Titanium doped Tungsten oxide (WO3) for TCO application. The ultimate goal is making novel, cheaper, and efficient TCOs based on W-Ti-O films. Titanium will enhance the conductivity …

Experimental Studies Of Lox/Ch4 Uni-Element Shear Coaxial Injector Geometry, Vanessa Dorado-Martinez

Open Access Theses & Dissertations

The Center for Space Exploration Technology Research (cSETR) has developed a set of shear coaxial injectors as part of a system-level approach to study LOX/CH4 combustion. This Thesis describes the experimental studies involved in the characterization of the effects produced by two design injection face plate variables: post thickness and recession length. A testing program was developed to study the injectors' atomization process using LN2 as a substitute for LOX in cold flow and the flame anchoring mechanisms in hot firings. The cold flow testing stage was conducted to obtain liquid core measurements and compare its behavior between the different …

Experimental Investigation Of Syngas Flame Stability Using A Multi-Tube Fuel Injector In A High Pressure Combustor, Sergio Elzar Maldonado

Open Access Theses & Dissertations

Over 92% of the coal consumed by power plants is used to generate electricity in the United States (U.S.). The U.S. has the world's largest recoverable reserves of coal, it is estimated that reserves of coal will last more than 200 years based in current production and demand levels. Integrated Gasification Combined Cycle (IGCC) power plants aim to reduce the amount of pollutants by gasifying coal and producing synThesis gas. SynThesis gas, also known as syngas, is a product of coal gasification and can be used in gas turbines for energy production. Syngas is primarily a mixture of hydrogen and …

Optimization Of Uv-Led Curable Printing Material For Applications In Direct Writing Systems: Inkjet, Reverse Offset, And Micro Dispensing Gpd, Ada Judith Ortega Varela

Open Access Theses & Dissertations

The quality of a product fabricated by direct writing methods will depend greatly on the properties of the printing material and its compatibility with the printing process. Although multiple advances in developing printing inks and pastes with novel properties are being made, the potential those can bring to electronics is hindered by their stability and performance during the printing process. In this study a UV-LED curable acrylic material was used to test the optimization of inks and pastes for three of the most common direct writing systems: Piezo-type Inkjet, Reverse Offset Roll to Plate, and Micro Deposition. The viscosity of …

Design And Evaluation Of A High Temperature/Pressure Supercritical Carbon Dioxide Direct Tubular Receiver For Concentrating Solar Power Applications, Jesus Daniel Ortega

Open Access Theses & Dissertations

This work focuses on the development of a solar power thermal receiver for a supercritical-carbon dioxide (sCO2), Brayton power-cycle to produce ~1 MWe. Closed-loop sCO2 Brayton cycles are being evaluated in combination with concentrating solar power to provide higher thermal-to-electric conversion efficiencies relative to conventional steam Rankine cycles. High temperatures (923 - 973 K) and pressures (20 - 25 MPa) are required in the solar receiver to achieve thermal efficiencies of ~50%, making concentrating solar power (CSP) technologies a competitive alternative to current power generation methods. In this study, the CSP receiver is required to achieve an outlet temperature of …

Water Recovery From Silica Saturated Ro Concentrate By The Concentrate Enhanced Reverse Osmosis Process, Gautam Patwardhan

Open Access Theses & Dissertations

Membrane fouling due to silica precipitation during reverse osmosis (RO) continues to be documented as the most common challenge in attaining stable continuous operation of RO systems across water treatment plants (1). Silica scale precipitation is time dependent and involves multiple steps leading to aqueous polymerization, condensation of polymers to form colloids, and deposition onto a solid surface (2). Exceeding the solubility of silica, widely considered to be in the range of 100-140 ppm, under a pH of 8 at 25 °C by various researchers, results in the precipitation of silica on the membranes, thereby limiting water recovery. Once the …

Design And Development Of Implantable And Remote Controlled Distraction Osteogenesis Device For Limb Lengthening Practice In Children, Mario Eduardo Rodriguez De La O

Open Access Theses & Dissertations

Recent technology improvements have been positively affecting medical industry in recent years since procedures and equipment are more precise and reliable. Nevertheless, there are still surgical procedures and medical devices that not fully address specific needs according to medical experts. One of those necessities is focused on options available for children patients when subjected to a surgical procedure named distraction osteogenesis. In general, distraction osteogenesis is performed when skeletal deformities need to be corrected or when bone lengthening is required, typically a mechanism is utilized to elongate bone at a controlled rate. The existing osteodistraction methods for limb lengthening and …

Master's In Electrical Engineering, Ricardo Xavier Rodriguez

Open Access Theses & Dissertations

This project is a focus on characterizing the process for actualizing three dimensional structures out of a carbon nanostructure composite via a direct print additive manufacturing process. Manufacturing parts additively enables for realization of geometrically complex shapes that often times cannot be manufactured any other way. The specificity of a material's properties have to be such, that the processing method can precisely place and bond material to itself in a highly repeatable manner. Commercial materials for additive manufacturing are have been optimized with these goals in mind and, therefore, often times lack the rigor and robustness for many applications.

The …

Design Optimization Of The Heat Transfer Model For A High Heat Flux Test Facility, Linda Hyemin Yoon

Open Access Theses & Dissertations

There are a variety of fuels that are utilized for space applications and in recent years, environmentally friendly fuels have been of interest. In the case of bipropellant rocket systems, hydrocarbon fuels have come to the attention of scientists and engineers. In particular, liquid methane was of interest in this study because of its physical and chemical advantages over other fuels, such as liquid hydrogen. Rocket engines rise to very high temperatures and to avoid catastrophic mechanical failure, a cooling system must be implemented within the engine to cool the walls. To get a better understanding of the fluid flow …

Natural Selectivity Of Nickel And Vanadium In Crude Oil, Olienka P. De La O Fernandez

Open Access Theses & Dissertations

Nickel and Vanadium have always been found in crude oil all around the world. The metal content is found mainly in porphyrin structures in the asphaltene fraction of the petroleum. In order to determine the reason for this natural preference, a set of experiments testing thermodynamics, kinetics, and other factors were performed. Candidate metalloporphyrins containing Vanadyl, Chromium, Iron, Nickel, Copper and Zinc were analyzed through chemical reactions characterized using Silica Column Chromatography, HPLC, MS and UV-Visible. Theoretical analysis of the stability of metalloporphyrins was conducted using DFT/NRLMOL for computational calculation. The analysis of all factors leads us to conclude that …

Safety Measures For Trucks: A Comparison Between Eu And U.S., Jan Kapusta

Open Access Theses & Dissertations

Road transportation is playing an important role in almost all of the freight movements and contributes to the economy. It has the highest share in the modal division of transported goods. This situation is not about to change in next years to come. Therefore, it is necessary to change the current situation and create rules and regulations that would lead to decrease in number of accidents either in EU or in U.S. The goal of this research is to analyze selected parameters related to the safety of truck transportation in EU and in U.S. This thesis also identifies and compares …

Effect Of Multi-Tube Injector Geometry On Flame Stability And Nox Emission In A High Pressure Gas Turbine Combustor, Sudipa Sarker

Open Access Theses & Dissertations

Future generation gas turbine combustors for power production are expected to have the capability of operating on high hydrogen content fuels. To ensure the implementation of high hydrogen content (HHC) fuel in a power generation unit without negotiating with operational or emission advantages, the study of the flame stability regime and behavior of (HHC) fuel under gas turbine condition leads to the necessity of the development of an optically accessible high-pressure combustor. This Dissertation first presents the design of an optically high-pressure combustor facility based on 500 kW power and 1.5 MPa pressure which is the representative pressure of a …

A Robust Algorithm For Estimating The Balance Of Autonomic Nervous System With Application To Mental Fatigue Detection Using Photoplethysmographic (Ppg) Signals, Ajay Kumar Verma

Open Access Theses & Dissertations

Spectral- and time-domain analysis of Heart Rate Variability (HRV) signal is widely used as a quantitative marker of the Autonomic Nervous System (ANS) activity. A robust algorithm was developed to derive HRV from photoplethysmographic (PPG) signals, to compute FFT- and AR-based spectra of these HRV signals, and to determine time- and frequency-domain features. This algorithm has detrending, sample-rate reductions, false-peak removal, automatic peak detection, peak-to-peak (P-P) interval detection and correction, time-domain feature extraction, HRV signal generation, and spectral-domain feature extraction from the HRV signal. Adapting to the very low spectral contents of the input PPG signal is very helpful in …

3d Printed Spatially Variant Anisotropic Metamaterials, Cesar Roman Garcia

Open Access Theses & Dissertations

The recent advancement in 3D printing has created a new way to design electronics and electromagnetic devices. This allows for a new breed of non-planar designs to be used, fully exploiting all three dimensions like never before. More functions can be fit into the same amount of space, products with novel form factors can be more easily manufactured, interconnects can be routed more smoothly, interfaces can be better implemented, electrical and mechanical functions can be comingled, and entirely new device paradigms will be invented. When departing from traditional planar topologies many new problems arise like signal integrity, crosstalk, noise, and …

An Explanatory And Comparative Analysis Of Freight Transportation In Eu And U.S. Highways, Luis Alberto Hernandez

Open Access Theses & Dissertations

This thesis provides resources for data collection regarding road freight transportation in the Unites States and the European Union, as well as an explanatory description of data available at each source. Afterwards, individual analysis of the current state of affairs of the highway freight transportation systems in U.S. and EU are performed. Thereafter, an explanatory and comparative analysis between the two land freight transportation systems is performed in terms of regulatory authorities and associations, trucks volume flow, freight weight and volume flow, major issues affecting the system, infrastructure funding sources, and major logistics hubs. Besides, a correlation analysis was performed …

Alkali Promoted Molybdenum (Iv) Sulfide Based Catalysts, Development And Characterization For Alcohol Synthesis From Carbon Monoxide And Hydrogen, Belinda Delilah Molina

Open Access Theses & Dissertations

For more than a century transition metal sulfides (TMS) have been the anchor of hydro-processing fuels and upgrading bitumen and coal in refineries worldwide. As oil supplies dwindle and environmental laws become more stringent, there is a greater need for cleaner alternative fuels and/or synthetic fuels. The depletion of oil reserves and a rapidly increasing energy demand worldwide, together with the interest to reduce dependence on foreign oil makes alcohol production for fuels and chemicals via the Fischer Tropsch synthesis (FTS) very attractive. The original Fischer-Tropsch (FT) reaction is the heart of all gas-to-liquid technologies; it creates higher alcohols and …

Use Of Cosine Modulated Filter Bank To Quantify Human Muscle Fatigue Using Electromyography Signals Obtained During Isometric Voluntary Contractions, Liza Stephanie Rodriguez

Open Access Theses & Dissertations

As technology continues to advance, there continues to be an interest in applying engineering theories to solve medical problems. Technology has allowed researchers to investigate the properties and characteristics of the human body in hopes of emulating their complexities. The rising interest in the study of biopotentials for use in prosthetic limbs, exoskeletons and machine interfacing has led to a necessity to validate that the understanding of these signals is accurate. The study of biopotentials generated by muscles via a method known as electromyography (EMG) has improved the understanding of effects of rehabilitative treatments, assisted in diagnosing diseases, control of …

Hydrogen Generation From Ammonia Borane And Water Through The Combustion Reactions With Mechanically Alloyed Al/Mg Powder, Daniel Rodriguez

Open Access Theses & Dissertations

Finding and developing a safe and effective method for hydrogen storage is integral to its use as an alternative source of energy. The goal of the studies described in this Thesis was to investigate the feasibility of developing combustible hydrogen-generating compositions based on ammonia borane and novel energetic materials such as nanocomposite and mechanically alloyed reactive materials, recently obtained by Prof. Edward Dreizin's team at the New Jersey Institute of Technology (NJIT). Such compositions could be stored for long time and release hydrogen on demand, upon ignition. The first phase of the research included thermodynamic calculations for combustion of ammonia …

The Interfacial Fracture Of Bonded Materials And Composites, Kai Zhao

Open Access Theses & Dissertations

Adhesive bonding and composite materials have been widely used in manufacturing industry. Failure results from the weakest link in a structure and this is often the interface between two materials. In case of composites, it becomes the fiber and matrix interface. In case of bonded polymers, the bonding line is the interface. This Dissertation is focused on the interfacial fracture of bonded materials and composites. First, a systematic experimental investigation on adhesive bonding strengths of polymer/polymer and polymer/metal joints was conducted and the experimental results were compared with other researchers' work. Then, a modified short-beam shear approach is developed to …

Evaluation Of A Torch Ignition System For Propulsion, Robert Ellis

Open Access Theses & Dissertations

In recent years NASA has had a renewed interest in oxygen and methane as propellants for propulsion. The drive for this combination comes from several factors including ease of land- based storage, handling safety, in situ resource utilization, and a relatively clean burning process when compared with the widely used hypergolic propellants. This project is part of a larger goal of the Center for Space Exploration Technology Research (cSETR) to better understand all aspects of using LOX/CH4 propellants to create future hardware that is specially optimized for these propellants. This paper discusses the literature background and reasons that led to …

Design And Development Of A High Velocity Oxy-Fuel Thermal Spray Gun, Luisa Alejandra Cabrera Maynez

Open Access Theses & Dissertations

The High Velocity Oxy-Fuel (HVOF) system is a highly promising technique for the production of thermal barrier coatings (TBCs), helpful in the protection of materials exposed to extreme thermal and corrosive environments. Coatings generated through the technique are employed in industrial settings to extend product life, increase performance and decrease maintenance costs. HVOF yields lower porosity and higher adhesion TBCs when compared to similar thermal spraying processes. Though gas fuelled systems are the norm in this technique, there is a recent interest in employing liquids due to their low cost and increased deposit density. Economic and highly scalable, HVOF process …

Multi-Objective Border Patrolling Optimization Using Game Theory And Evolutionary Algorithms, Franciso Oswaldo Aguirre

Open Access Theses & Dissertations

Border security has evolved significantly since the days when no more than 75 Mounted Guards patrolled the U.S. border in the early 1900's. The border region includes thousands of miles of both land and maritime borders that must be controlled, as well as commercial transportation networks. One of the primary components of the Department of Homeland Security (DHS) is the U.S. Customs and Border Protection (CBP) agency. One of the most typical activities performed by CBP is patrolling the expansive open areas in between official points of entry (POEs) to prohibit illegal entry attempts. Roving patrols are routinely conducted by …

An Intelligent System For High Resolution Radar Systems, Janette C. Briones

Open Access Theses & Dissertations

Cognitive radio is a recent, novel approach that integrates machine perception software into wireless systems. The term cognitive radio was first used by Joe Mitola. The concept and the term cognitive radio quickly caught the attention and interest of many in the communications field. Cognitive radios are capable of making decisions and selecting or modifying the operating parameters of a radio. Given these capabilities, it is feasible to build a cognitive radar system as introduced by Simon Haykin in 2006. Cognitive radar, as described by Haykin, is an intelligent system that must be aware of its environment, uses prior knowledge, …

Development Of A Variable Stiffness Locally Adjustable And Repairable Low-Cost Energy Storage And Return Carbon Fiber Prosthetic Foot: A Feasibility Study, Joshua Scott Bowen

Open Access Theses & Dissertations

Background: Energy storage and return (ESAR) prosthetic feet were developed to improve the mobility and function of lower-limb amputees. Amputees in the Developing World amputees lack this technology. Most current Developing World prosthetic solutions do not adequately address the needs of active amputees and were not designed to pass international standard tests. Developing a low-cost, repairable, adjustable, energy storage and return prosthetic foot would close this technological gap and improve the mobility and function of active amputees. The goal of this research is to determine the feasibility of fabricating a low-cost, adjustable, ESAR, repairable prosthetic foot manufactured from carbon fiber …

Solar Pv Power Generation Forecasting Using Hybrid Intelligent Algorithms And Uncertainty Quantification Based On Bootstrap Confidence Intervals, Donna Alhakeem

Open Access Theses & Dissertations

This Thesis focuses on short-term photovoltaic forecasting (STPVF) for the power generation of a solar PV system using probabilistic forecasts and deterministic forecasts. Uncertainty estimation, in the form of a probabilistic forecast, is emphasized in this Thesis to quantify the uncertainties of the deterministic forecasts. Two hybrid intelligent models are proposed in two separate chapters to perform the STPVF. In Chapter 4, the framework of the deterministic proposed hybrid intelligent model is presented, which is a combination of wavelet transform (WT) that is a data filtering technique and a soft computing model (SCM) that is generalized regression neural network (GRNN). …

Examining The Role Of Attention In Steering Using A Dual Task Paradigm, Venkata Naga Pradeep Ambati

Open Access Theses & Dissertations

Changing the direction of locomotion, often referred to as "steering", is an integral component of human locomotion. Steering requires maintaining dynamic balance while translating and rotating the body in the new travel direction. Given the level of sensation thought to be involved in sub serving goal directed modifications in steering, it is highly likely that steering control may require attention. Since attention resources decline with increasing age, we may see the influence of age on steering performance when attention resources are limited. Therefore, this study sought to investigate the role of attention in steering using a dual task paradigm in …

The Study Of The Dielectric Properties Of The Endohedral Fullerenes, Shusil Bhusal

Open Access Theses & Dissertations

Dielectric response of the metal nitride fullerenes is studied using the density functional theory at the all-electron level using generalized gradient approximation. The dielectric response is studied by computing the static dipole polarizabilities using the finite field method, i.e. by numerically differentiating the dipole moments with respect to electric field. The endohedral fullerenes studied in this work are Sc3N@C68(6140), Sc3N@C68(6146), Sc3N@C70(7854), Sc3N@C70(7960), Sc3N@C76(17490), Sc3N@C78(22010), Sc3N@C80(31923), Sc3N@C80(31924), Sc3N@C82(39663), Sc3N@C90(43), Sc3N@C90(44), Sc3N@C92(85), Sc3N@C94(121), Sc3N@C96(186), Sc3N@C98(166). Using the Voronoi and Hirschfield approaches as implemented in our NRLMOL code, we determine the atomic contributions to the total polarizability. The site-specific contributions to the polarizability …

A Circuit-Based Algorithm For Two-Phase Flow At The Pore Scale In Porous Media, Todd Dorethy

Open Access Theses & Dissertations

Models of two-phase flow in porous media are of practical interest in many fields of science and engineering such as in oil recovery and hydrology. For this class of problem, an immiscible fluid is injected into a single-phase, porous medium to evict its valuable, native fluid. Because the aim is to amass as much of the indigenous fluid as possible, models attempt to output reliable flow regime patterns depicting how well the invading fluid displaces the native fluid.

Flow regime patterns generally depend upon the geometry of the domain, stimulation at the boundaries, and properties of the invading and native …