Engineering Commons^™

Comparison Of Reynolds-Averaged Navier-Stokes Turbulence Models For Simulating Boundary Layers In Hypersonic Flows, Jorge-Valentino Kurose Bretzke

Masters Theses

“This study describes the use of Computational Fluid Dynamics (CFD) codes to simulate hypersonic boundary layers using several different turbulent closure models and comparing Reynolds-Averaged Navier-Stokes (RANS) simulations against Direct Numerical Simulations (DNS) of similar test cases. The test cases in this study consist of a flat plate in a Mach 8 freestream with a zero pressure gradient and wall recovery ratio of 0.48, as well as a Mach 8 axisymmetric nozzle also with a cold wall. The RANS models used in this study are the Spalart-Allmaras model, Baldwin-Lomax model, Menter K-Omega Baseline and Menter K-Omega Shear Stress Transport models. …

On The Investigation Of Hot Tearing Behavior Of Continuous Cast Steel, Yanru Lu

Masters Theses

”Hot tearing has long been recognized as a major problem that plagues the development of the continuous casting process and results in low-quality products. Understanding of the mechanisms and the required conditions for the hot tearing formation is important for industries but has not been well-established yet. Thus, this research focuses on the hot tearing issue observed in continuous cast steel, by providing a summary of the current research progress and then introducing a new laboratory method to determine the thermo-mechanical properties relevant to hot tearing of different steel grades under different solidification conditions. In this method, an apparatus was …

Additive Manufacturing Of Linear Shaped Charges To Address Run Up And Run Down Phenomena, Jason Ho

Masters Theses

”A shaped charge is an explosive device used to focus detonation energy in a desired direction. Additive Manufacturing (AM) can allow greater design freedom and geometric complexity for the liner portion of the shaped charge.

In this work, the following hypotheses were tested: 1) Adjusting the initial apex angle of a linear shaped charge liner reduces the amount of run up that occurs, and 2) implementing a backstop at the end of a linear shaped charge liner reduces the amount of run down that occurs.

Linear shaped charge liners with a continuously changing apex angle were created with additive manufacturing. …

Characterization Of A Plasma Source Simulating Solar Wind Plasma In A Vacuum Chamber, Blake Anthony Folta

Masters Theses

"The United States has set an aggressive time line to not only return to the Moon, but also to establish a sustained human presence. In the Apollo missions dust was a significant factor, but the duration of those missions was short so dust and surface charging were problems, but they did not pose an immediate threat. For a long-term mission, these problems instead become incredibly detrimental. Because of this, research needs to be conducted to investigate these phenomena so that mitigation techniques can be developed and tested. To this end, this thesis serves to demonstrate the Gas and Plasma Dynamics …

Performance Evaluation Of Alsi10mg Fabricated By A Selective Laser Melting Process, David Michael Murphy

Masters Theses

“Selective laser melting is becoming a widely used additive manufacturing technique that melts metal powder in a layer by layer process in order to build a desired part or geometry. Like many additive processes, selective laser melting allows for fabrication of parts with complex geometries. In order to fabricate a fully dense part there are a number of variables to take into account including: powder characteristics, laser parameters, and environmental parameters. Each of these variables can affect the microstructure and thus the mechanical performance of an additively manufactured part. In this work, the aluminum alloy AlSi10Mg was investigated. AlSi10Mg is …

Modal Analysis As Non-Destructive Testing Technique For Additively Manufactured 304l Stainless Steel Parts, Tristan N. Cullom

Masters Theses

“Non-Destructive Testing (NDT) methods for Additively Manufactured (AM) parts is an ongoing field of research in the additive community due to its ability to determine if a part can be deemed viable for field usage. This study presents modal analysis as a NDT method for AM parts. For production builds that have multiple copies of the same part, a correcting technique can be used such that the frequencies of the parts under test can be reliably compared against each other, which saves both time and money compared to other traditional NDT methods. This study was able to develop a novel …

3d Printing Reinforced Concrete Structures, Bryce Tyler Tafolla

Masters Theses

"This study aims to investigate a 3D printing method to directly incorporate continuous reinforcement into concrete structures. The ability to design and produce complex structures with optimized topographical configuration can be used to reduce potential material waste while maintaining the required structural strength. Furthermore, the ability to actively incorporate reinforcement into printed members substantially reduces potential labor requirements and eliminates the need to set up formwork.

The study began its initial approach with a manual extrusion process containing reinforcement to observe the necessary constraints required to achieve a printing system with this functionality. The second stage of development was designing …

Influence Of Input Energy On Mechanical Properties Of Laser Powder Bed Fused Aisi 304l Stainless Steel, Tan Pan

Masters Theses

“Powder Bed Fusion process with selective laser melting technique is popularly adopted in additive manufacturing area on account of its layer by layer manufacturing fashion capable of fabricating components with complex internal and external geometries and structures. However, the process-property map is unique and vital for different materials and AM configurations used for fabrication. The process parameter is identified as a significant factor that heavily influences the properties and performances of the printed materials.

Current work aimed to extend the existing knowledge on Laser Powder Bed Fusion fabricated AISI 304L by accessing the influence of varying energy input on the …

Inclusion Control In Steel Castings, Koushik Karthikeyan Balasubramanian

Masters Theses

“Non-metallic inclusions are mainly comprised of oxides, sulfides, and nitrides, and are formed in liquid steel during the melting and refining process, as a result of reoxidation, worn-out refractories, or entrained slag. The notch toughness of high strength steels is particularly susceptible to the type, number, size, and distribution of non-metallic inclusions. High manganese and aluminum austenitic steels, or Fe-Mn-Al steels, have gained much interest in the military and automotive sector because of their excellent combinations of high strength and toughness. However, these steels are subject to both oxide bifilms and aluminum nitride, AlN, inclusions which form during melting and …

Optical Fiber Based Integrity Test Of Civil Engineering Materials: Numerical Analysis, Ruoyu Zhong

Masters Theses

“Major advancement in Civil Engineering cannot be accomplished without the help of sensors. Among different types of sensors, fiber-optic sensor is known for its light weight, high accuracy, resolution, immunity to electromagnetic interference, and resistance to harsh environment. This research mainly focuses on fiber-optic sensor application on concrete structures as temperature sensor. Thermal Integrity Profiling (TIP) is a non-destructive integrity testing method which makes use of the hydration heat from the concrete curing process to detect defects within a drilled shaft. Any defect of concrete could result in a temperature anomaly in a drilled shaft. The accuracy of the current …

Development Of Amine-Functionalized Mesoporous Alumina For Radioiodine Removal From Water, Mansour Mohammed Alsalbokh

Masters Theses

“Radioactive materials have spread due to careless disposal and nuclear disasters. Some radionuclides can exist in an aqueous media, like radioactive iodine. As a result, in this work amine-functionalized mesoporous alumina was developed to adsorb radioactive iodine from the liquid phase. Bismuth was incorporated, using a wet impregnation method, to test it as a possible silver replacement. Amine grafting was used to functionalize the surface of the mesoporous alumina. All materials prepared in this work were characterized by N₂ physisorption, FTIR and TGA to determine the textural properties, surface functionality, and amine loading. The synthesized materials were tested for …

Mid-Infrared Chiral Metsurface Coupling With Molecular Vibration, Md Shamim Mahmud

Masters Theses

“The mid-infrared design of chiral metamaterial shows a tremendous absorption capability of infrared rays, and it has the significant application of circular dichroism based device development. Plasmon-phonon coupling is one of the application of metamaterial that provides a new path for tailoring the surface in the nanoscale, which is also applicable in molecules detection. It is possible to change the Plasmon-Phonon coupling strength not only through the chemical change of molecules but also by changing the metamaterial light-matter interaction property. So far, linearly polarized light shows the strong coupling between metamaterial and molecules. However, it is possible to observe strong …

Data Analytics Of Natural Gas Injection Enhanced Oil Recovery For Unconventional Reservoirs, Ali Waqar

Masters Theses

"Unconventional Enhanced Oil recovery, via the injection of natural gas has attracted great attention, as studies and projects have shown to be promising. An overview of pertinent studies has been carried out. Core Scale Laboratory Experiments, Core Scale Simulation, Field Scale simulation and pilot projects are analyzed. Data is collected for Core, Reservoir, Operational, and recovery information. Thereafter, Data analysis techniques are applied to identify data ranges, distributions, trends, relationships, and to eventually reach conclusions.

Huff and Puff injection is the preferred mode of injection, delivering most promising results for unconventional reservoirs. Across all the studies, with increase in amount …

Prediction Of Crack Propagation In Zrb₂-Carbon Based Composites Using The Extended Finite Element Method, Leiren Danielle Jarvis

Masters Theses

“The ultra-high temperature ceramic, zirconium diboride (ZrB₂) has long been researched for applications in extreme environments. Its high strength (> 400 MPa) and thermal conductivity (> 100 W/m•K) make it a candidate for use in hypersonic fight, but a low fracture toughness (< 3 MPa•m^1/2) limits this use. In order to increase the fracture toughness without compromising the strength and thermal conductivity, experimental research has focused on the viability of engineered architectures using multiple materials to create a macrostructure. These architectures allow for the increase of fracture toughness thru crack deflection in the material.

Two architectures in particular, …

Micro-Analysis Of Contaminants In Suspended Load And Bank Deposits From The Mineral Fork Creek Watershed In Potosi, Missouri, 2019-2020, William Joseph Miller

Masters Theses

”There are rising concerns pertaining to water contamination produced by toxic heavy metal contaminants such as lead and zinc. For this study, lead, zinc, and barite are three identified contaminants currently threatening Missouri water supplies. A microanalysis of the amounts of lead, zinc, and barite in the water of Mineral Fork Creek was conducted, involving both field and laboratory work. The purpose of the study was to determine the levels of lead, zinc, and barite contaminants, contributing to Big River, by Mineral Fork Creek, in Potosi Missouri, Washington County.

This research study uses a quantitative micro-analysis approach to determine the …

Modeling And Control Of Cascaded Bridgeless Multilevel Rectifier Under Unbalanced Load Conditions, Sai Hemanth Kankanala

Masters Theses

“The goal of this project is to model and control a novel unidirectional cascaded multilevel bridgeless rectifier as an active front end in medium and high voltage applications. This topology has many advantages over a conventional cascaded H-bridge rectifier, such as lower implementation cost, higher reliability, and greater flexibility with similar power quality. The complete design process of the proposed converter is developed step by step in order to meet all the desired objectives. The steady-state mathematical model is used to develop a method for the voltage balancing of dc cells. Power factor analysis is discussed to mathematically derive requirements …

Soil-Water-Energy Nexus Of Green Roofs, Katherine Ann Bartels

Masters Theses

"As the urban landscape continues to sprawl into previously undeveloped land to accommodate population growth, the need to design cities that effectively manage urban stormwater is imperative for a sustainable future. Green roofs use rain-harvesting techniques to reduce urban stormwater discharge while simultaneously providing traditional roof services as well as several ecosystem services. However, green roof media design varies greatly among commercial applications, and little guidance is available to engineers when selecting the media for prospective green roofs. Efforts to maximize stormwater retention and enhance urban heat island mitigation capabilities of green roofs while concurrently reducing nutrient loading were examined …

Design And Development Of Power Processing Units For Applications In Electrically-Propelled Satellite Systems, Kartikeya Jayadurga Prasad Veeramraju

Masters Theses

"Electrospray technology provides a way to ionize specialized liquids by applying high voltages across a sharp porous tip and a metallic mesh. This technology is widely used in the field of mass spectroscopy for generating ions for testing purposes. The dawn of nano-satellites posed new challenges in the miniaturization of many conventional satellite sub-systems. One significant challenge faced in such a process was the miniaturization of the propulsion system. Electrosprays have started to find their application in the field of Aerospace Engineering and now are formally known as Electrospray Thrusters. These thrusters provide high specific impulse and are attractive substitutes …

Experimental Evaluation Of A Honeycomb Structure In Open Channel Flows, Kyle David Hix

Masters Theses

“Designing and controlling open channel flows presents many challenges. One such challenge is energy dissipation. This challenge is currently addressed by several means, including the use of honeycomb structures. Energy dissipation by honeycomb structures has been studied for pressurized conduit flows; however, their ability to dissipate energy in free-surface flows remains largely unexamined. This work introduces a comprehensive experimental study designed to estimate the energy dissipation through a honeycomb structure in a free-surface flow.

This work examined the energy dissipation for a range of flows, pipe lengths, and pipe diameters in two flumes. PVC pipes ranging from 6 inches to …

In-Situ X-Ray Imaging Of The Selective Laser Melting Process, Meelap M. Coday

Masters Theses

"Fusion-based metal additive manufacturing (AM) has garnered much interest in recent decades. Despite the popularity of fusion-based AM technologies such as selective laser melting (SLM), there are still fundamental questions and uncertainties that need to be addressed. In this work, we focus on the understanding of the undercooling in the SLM process and the uncertainties induced by the laser beam size, power, and scan speed. First, we report the estimation of undercooling in the SLM process from the solidification rate measured by in-situ high-speed synchrotron x-ray imaging, based on the dendrite growth velocity model. The undercooling changes as a function …

Shock Wave Propagation Behavior At Corners And Crosscuts In Five Small-Scale Tunnel Scenarios, David Pierre Doucet

Masters Theses

"Shock wave propagation in tunnels and other enclosed environments is substantially more complicated than in an open-air or even a surface detonation. There is still much to learn about how shock wave properties change as a wave propagates in an enclosed space, such as a mine tunnel, inside of a building, or city street. The geometry of the enclosure will have a large role in the propagation of the shock wave. This means that many different tunnel designs must be studied. This work tested five different designs using a modular small-scale model. The scenarios tested were Straight-line, Single Turn, Around …

Evaluation Of Engineering Properties Of Soil In Al Butayn, Mudarraj Al Qassim And Turubah - Hail Saudi Arabia, Turki Essam A. Sehly

Masters Theses

"Fractures, sinkhole, building cracks, and ground subsidence have spread in many regions of the Kingdom of Saudi Arabia, some of which are related to seismic activity, others due to the presence of unstable soils (collapsing soils and Expansive soils) and others because of faults, while others result from drawing groundwater at great rates. The current study has several facts related to the formation of cracks and landslides, including:
1) A general study of geomorphology and geology of the study areas.
2) The causes affecting the formation of cracks and subsidence.
3) Detailed geomorphological and geological studies of the locations of …

Serdes Channel Crosstalk Mitigation Methodology With Industrial Implementation Guidance, Junda Wang

Masters Theses

"With the increasing data rate of digital circuits, the differential crosstalk degrades the signal integrity performance in PCBs drastically. Usually, in the trace area, crosstalk can be isolated by stitching vias and adding shielding ground vias can also shield coupling in the ball gate array (BGA) and pin field area. The traditional way to mitigation crosstalk in the BGA and pin field area through adding more ground vias between signal pairs or increasing the spacing in between, it demonstrated us the efficiency on crosstalk cancellation efficiency but it also increases the size of products and it would be contradictory to …

Microgel Placement And Plugging Performance In Sand Filled Fracture For Conformance Control, Baihua Lin

Masters Theses

“Preformed particle gels (PPG) has been widely applied for conformance control in heterogeneous reservoirs with fractures and super-K channels. As a plugging agent, PPG could plug the fractures or high permeability streaks and divert the displacing fluid into low permeability matrix. Many studies have been conducted to investigate the potential of PPGs as a water cut reduction and improved oil recovery agent using homogeneous sandpacks or heterogeneous core samples with man-made open fractures. However, no research has been carried out to understand how PPG injection and plugging performance will be changed if the fractures are filled with sands. Herein, the …

Intrinsic Mechanical Properties Of Zirconium Carbide Ceramics, Nicole Mary Korklan

Masters Theses

“This research focuses on the processing and mechanical properties of zirconium carbide ceramics (ZrC_x). The first goal of this project was to densify near stoichiometric (i.e., x as close to 1 as possible) and nominally phase pure ZrC_x. The maximum stoichiometry achieved for the ZrC_x (C/Zr ratio of 0.92) was measured using gas fusion analysis. Hot pressing was used to obtain dense ZrC_x. Archimedes was used to determine the relative density of hot pressed ZrC_x at > 95%. Scanning electron microscopy (SEM) was used to determine the overall microstructure of the hot pressed …

Design And Comparison Of Unoptimized And Optimized Gray Code Multi-Level Systems, Shirly Adams Gamliel

Masters Theses

“As the conventional binary MOS-based VLSI technology is reaching limitations in chip area, speed, and power, new technologies are being researched. Some such technologies relate to multi-level logic design. This thesis explores the process and benefits of applying and optimizing multi-level design techniques to an existing Gray code binary system. Specifically, the multi-level system is designed using CoreMem technology and is optimized using Indira Dugganapally’s optimization techniques.

The first step is generating the n-bit binary and quaternary truth tables for an encoder’s Gray code output and additional desired data. Then, the data for each n-bit system is arranged in multi-level …

Combining Laser Aided Ablation And Polishing To Minimize Surface Roughness Of Additively Manufactured Aluminium Components, Sahil Bipinkumar Patel

Masters Theses

“The surface roughness of additively manufactured parts is much higher than the acceptable range for most applications, thus post-processing is needed to qualify these parts for use. Laser polishing can be used to bring the surface roughness in an admissible range, but if the initial roughness is very high then the energy density for the polishing process needs to be very high to achieve a significant reduction in roughness. This high energy density can produce many process defects. Also, laser polishing alone cannot get rid of high wavelength asperities. Any waviness in the part can be linked with initial waviness …

Analysis Of Energy Economy In Muon Catalyzed Fusion Considering External X-Ray Reactivation, Nishant Raghav Pillai

Masters Theses

"An analysis of the energy economy of a theoretical muon-catalyzed nuclear fusion system has been made by invoking the use of point kinetic equations, Monte Carlo radiation transport simulations, and from a review of existing literature on muon-catalyzed fusion. An external X-ray reactivation source is proposed as a novel way to increase the number of fusions per muon and thereby overcome the so-called alpha sticking problem that has long been considered the primary impediment to breakeven muon-catalyzed fusion power. Free electron lasers, synchrotrons and Wakefield accelerators are discussed as possible bright X-ray photon sources. The addition of an intense external …

Evaluation Of Eor Potential Of Low Salinity Polymer In Enhancing Heavy Oil Recovery On The Alaska North Slope, Shize Yin

Masters Theses

"Alaska's North Slope (ANS) contains vast amount of viscous oil resources that have not been extracted. This study focuses on the investigation over the potential shown by low-salinity polymer flooding in improving the recovery of ANS heavy oil through laboratory experiments.

At the beginning, coreflooding experiments were performed with silica sandpacks. The synergy between low-salinity water flooding and polymer flooding was proved, and the low-salinity polymer showed a better performance than the normal-salinity polymer. Further, the sandpacks prepared with formation sand from an oilfield on the ANS was then employed so as to simulate the reservoir condition. A series of …

Feasibility Study On Novel Fire-Resistant Coating Materials, Anyou Zhu

Masters Theses

“Over the past decades, wildfires in the United States have caused severe damage and property losses. The California Camp Fire in November 2018 caused 85 civilian fatalities and destroyed 18,793 structures. There is a need to enhance the fire resistance of structures and buildings. The primary purpose of this study was to develop innovative surface-bonded fire-resistant material that can be used as a wall coating with three primary features: (a) workability for application, (b) enough adhesion to the surface of the structure, (c) fire-resistant. This research developed mix designs of innovative fire-resistant coating materials including high-performance cement mortar (HPCM), geopolymer …