Mechanical Engineering Commons^™

Molecular Combing Of Dna Nanofibers And Comparison To Electrospinning, Tanner L. Buresh

UCARE: Research Products

The goal of these experiments was to create DNA nanofibers through the method of molecular combing (MC) and then compare the MC fibers to fibers created with electrospinning (ES). The experiment was designed and initial samples were created. After confirming that the method would succeed in creating DNA fibers, several parametric studies were performed in order to optimize the experiment and create the most uniform fibers possible. The parametric studies were done on the following variables: substrate material, pH level of DNA solution, and DNA solution concentration. After completion of all experiments, it was determined that although fibers could be …

Parametric Analysis Of A Solid Oxide Fuel Cell Auxiliary Power Unit Operating On Syngas Produced By Autothermal Reforming Of Hydrocarbon Fuels, Jun Dong, Xinhai Xu, Ben Xu, Shuyang Zhang

Mechanical Engineering Faculty Publications

A 1 kWe integrated auxiliary power unit (APU) system consisting of an autothermal reformer and a solid oxide fuel cell (SOFC) unit, as well as balance-of-plant components, was designed and analyzed. A relatively easy-to-approach SOFC model was developed in order to conveniently calculate V-I and P-I curves and the system's net efficiency at different operating conditions. The effects of steam to carbon and oxygen to carbon ratios in the reactants, channel dimensions of the SOFC unit, and hydrocarbon fuel types on the integrated APU system's performance were discussed. Five hydrocarbon fuels including diesel, Jet-A, gasoline, ethanol, and methanol were studied …

Spatio-Temporal Linear Stability Analysis Of Stratified Planar Wakes: Velocity And Density Asymmetry Effects, Benjamin Emerson, Swapnil Jagtap, J. Mathew Quinlan, Michael W. Renfro, Baki M. Cetegen, Tim Lieuwen

Mechanical Engineering Faculty Publications

This paper explores the hydrodynamic stability of bluff body wakes with non-uniform mean density, asymmetric mean density, and velocity profiles. This work is motivated by experiments [S. Tuttle et al., “Lean blow off behavior of asymmetrically-fueled bluff body-stabilized flames,” Combust. Flame 160, 1677 (2013)], which investigated reacting wakes with equivalence ratio stratification and, hence, asymmetry in the base flow density profiles. They showed that highly stratified cases exhibited strong, narrowband oscillations, suggestive of global hydrodynamic instability. In this paper, we present a local hydrodynamic stability analysis for non-uniform density wakes that includes base flow asymmetry. The results show …

Densification Of W-Ni-Fe Powders Using Laser Sintering, Xuan Wang, Matthew Wraith, Stephen Burke, Howard Rathbun, Kyle Devlugt

Industrial and Manufacturing Engineering

In this paper, Laser Sintering (LS) of 90%W–7%Ni–3%Fe (wt.%) powders have been investigated, with the goal to understand the influence of final density by laser power, scanning speed, laser trace width, and the number of scanning passes. The results suggest that the laser power and scanning speed are the most important factors influencing density; the influence of trace width and number of scanning passes are not significant. With the increase of laser power and decrease of scanning speed, higher density can be achieved. The microstructure analysis indicated that the porosity changed from open porosity to closed porosity with higher laser …

Multi-Axial Failure Of High-Performance Fiber During Transverse Impact, Matthew C. Hudspeth

Open Access Dissertations

The effect of projectile nose geometry on ensuing wave development in high-performance yarns is explored during single yarn transverse impact. Special attention has been placed on visualizing the immediate region around the projectile-yarn contact site for 0.30-cal round, 0.30-cal fragment simulation projectiles (FSP), and razor blades using high-speed imaging. Kevlar® KM2, Dyneema®SK76 and AuTx have been impacted at velocities ranging from ∼100 m/s to ∼1200 m/s depending on projectile nose shape, with an emphasis set on determining the critical velocity wherein below said velocity significant development of wave propagation occurs and above said velocity the yarn fails immediately upon impact. …

Preliminary Design Tools In Turbomachinery: Non-Uniformly Spaced Blade Rows, Multistage Interaction, Unsteady Radial Waves, And Propeller Horizontal-Axis Turbine Optimization, Yujun Leng

Open Access Dissertations

Turbomachinery flow fields are inherently unsteady and complex which makes the related CFD analyses computationally intensive. Physically based preliminary design tools are desirable for parametric studies early in the design stage, and to provide deep physical insight and a good starting point for the later CFD analyses. Four analytical/semi-analytical models are developed in this study: 1) a generalized flat plate cascade model for investigating the unsteady aerodynamics of a blade row with non-uniformly spaced blades; 2) a multistage interaction model for investigating rotor-stator interactions; 3) an analytical solution for quantifying the impeller wake convection and pressure wave propagating between a …

A Study On The Sustainable Machining Of Titanium Alloy, Abdulhameed Alaa Dawood

Masters Theses & Specialist Projects

Titanium and its alloy (Ti-6Al-4V) are widely used in aerospace industries because of their light weight, high specific strength, and corrosion resistance. This study conducted a comparative experimental analysis of the machinability of Ti-6Al-4V for conventional flood coolant machining and sustainable dry machining. The effect of cutting speed, feed rate, and depth of cut on machining performance has been evaluated for both conditions. The machining time and surface roughness were found to be lower in dry machining compared to flood coolant machining. The tool wear was found to be unpredictable, and no significant difference was observed for dry and coolant …

Optimization Of Process Parameters In Micro Electrical Discharge Machining (Edm) Of Ti-6al-4v Alloy, Farshid Alavi

Masters Theses & Specialist Projects

Ti-6Al-4V has a wide range of applications such as in the automotive and aerospace industries. Nevertheless, titanium alloys are very difficult to machine by conventional methods. Micro-EDM is a non-conventional machining method that uses the thermal effect of precisely controlled sparks. Manufacturers are looking for the methods and optimal settings to increase the productivity of micro-EDM in terms of lessening machining time and tool wear. Moreover, surface integrity of the machined area is crucial for some products such as biomedical implants.

The objective of this study was to investigate the effects of the micro-EDM process parameters on response variables, in …

A Comparison Of American, Norwegian, And Russian Standards In Calculating The Wall Thickness Of Submarine Gas Pipeline, Cindy Dianita, Tatyana Vladimirovna Dmitrieva

Makara Journal of Technology

One of the key issues in the pipeline design is wall thickness calculation. This paper highlights a comparison of wall thickness calculation methods of submarine gas pipeline based on Norwegian Standard (DNV-OS-F101), Indonesian Standard SNI 3474 which refers to American Standard (ASME B31.8), and Russian Standard (VN39-1.9-005-98). A calculation of wall thickness for a submarine gas pipeline in Indonesia (pressure 12 MPa, external diameter 668 mm) gives the results of 18.2 mm (VN39-1.9-005-98), 16 mm (ASME B31.8), and 13.5 mm (DNV-OS-F101).The design formula of hoop stress due to internal pressure is interpreted in different ways for every standard. Only Norwegian …

Stiffness Reduction Strategies For Additively Manufactured Compliant Mechanisms, Ezekiel G. Merriam

Theses and Dissertations

This work develops and examines design strategies for reducing the stiffness of 3D-printed compliant mechanisms. The three aspects of a flexure that determine its stiffness are well known: material, boundary conditions, and geometry. In a highly constrained design space however, flexure stiffness may remain unacceptably high even while arriving at the limits of design constraints. In this work, changes to geometry and boundary conditions are examined that lead to drastically reduced stiffness behavior without changing flexure thickness, width, or length. Changes to geometry can result in very complex mechanisms. However, 3D printing enables almost arbitrarily complex geometries. This dissertation presents …

Concurrent Spatial Mapping Of The Viscoelastic Behavior Of Heterogeneous Soft Materials Via A Polymer-Based Microfluidic Device, Wenting Gu

Mechanical & Aerospace Engineering Theses & Dissertations

This dissertation presents a novel experimental technique, namely concurrent spatial mapping (CSM), for measuring the viscoelastic behavior of heterogeneous soft materials via a polymer-based microfluidic device. Comprised of a compliant polymer microstructure and an array of electrolyte-enabled distributed resistive transducers, the microfluidic device detects both static and dynamic distributed loads. Distributed loads deform the polymer microstructure and are recorded as resistance changes at the locations of the transducers.

The CSM technique identifies the elastic modulus of soft materials by applying a precisely controlled indentation depth using a rigid probe to a sample placed on the device. The spatially-varying elastic modulus …

Secondary Electron Emission From Plasma Processed Accelerating Cavity Grade Niobium, Miloš Bašović

Mechanical & Aerospace Engineering Theses & Dissertations

Advances in the particle accelerator technology have enabled numerous fundamental discoveries in 20th century physics. Extensive interdisciplinary research has always supported further development of accelerator technology in efforts of reaching each new energy frontier.

Accelerating cavities, which are used to transfer energy to accelerated charged particles, have been one of the main focuses of research and development in the particle accelerator field. Over the last fifty years, in the race to break energy barriers, there has been constant improvement of the maximum stable accelerating field achieved in accelerating cavities. Every increase in the maximum attainable accelerating fields allowed for higher …

Impact Of Additive Manufacturing Technologies And The Development Ofa Mixed Metal Powderbed Additive Manufacturing System, Gerald L. Knapp

Honors Capstones

No abstract provided.

Effect Of The Use Of Natural Gas-Diesel Fuel Mixture On Performance, Emissions And Combustion Characteristics Of A Compression-Ignition Engine, Y. Karagoz, T. Sandalci, Ümit Özgür Köylü, A. S. Dalkilic, S. Wongwises

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

Optical Nonlocality Induced Zitterbewegung Near The Dirac Point In Metal-Dielectric Multilayer Metamaterials, L. Sun, Jie Gao, Xiaodong Yang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

Oscillatory Flow Mechanism For Enhanced Heat Transfer, Sultan Taher Raml

Doctoral Dissertations and Master's Theses

This research project is about the use of an oscillatory flow mechanism to enhance heat transfer. The idea behind this is to induce oscillation of the end wall of one of two connected chambers of a heat exchanger which effectively will induce oscillation of the boundary layer within the connecting duct. The main idea of this thesis came from using species separation studies before 40 years ago in hyperventilation technology to help patients under anesthesia in hospitals. There are many applications for this research such as removing heat from chemical reactors, electrical devices and other enclosed environments such as submarines, …

Improving Damage Tolerance Of Composite Sandwich Structures Subjected To Low Velocity Impact Loading: Experimental And Numerical Analysis, Ravi B. Gondaliya

Doctoral Dissertations and Master's Theses

Sandwich structures with composite facing skins have seen applications in variety of sectors including aerospace and automobile, owing to their high specific mechanical properties. However, there is a need to develop better damage tolerant sandwich structures since conventional composite facing skins exhibit low impact resistance in the transverse direction. Here, composite skin sandwich structures with three different impact resistant core materials were fabricated and tested both experimentally and numerically. Neat CFRP and 2024-T3 aluminum alloy sheets were also investigated. Cores utilizing impact resistant D3O® were found to have very favorable weight specific energy absorbing properties at higher impact velocities as …

Model And Control Development Of Hybrid Fuel Cell And Battery Power System For Uas (Quadcopter), Mohammad Biswas

Faculty Posters

This poster was presented during the UT Tyler Faculty Research Poster Showcase 2016.

Design And Prototyping Of A Variable Geometry Extrusion Die To Exhibit Significant Alteration Of Shape, David C. Bell

Honors Theses

Extruded parts are conventionally made by forcing melted plastic through a steel die having a fixed opening that matches the shape of the part. Plastic parts made by extrusion include weather stripping, PVC pipe, and composite lumber. Variable geometry dies can change their opening shape during the extrusion process. Developing shape-changing dies technology offers the possibility of making parts with varying cross-sections that currently need to be made through injection molding. This is desirable as, compared to molding, extrusion tends to be faster and less expensive. Variable geometry extrusion dies have been designed and prototyped by the University of Dayton …

Nonlinear Analysis Of Balance Data In The Easter Seals Adult Day Services Population, Taylor Marie Schemmel

Honors Theses

81.1 million adults are expected to be affected by dementia in 2040. Individuals with dementia are twice as likely to fall as healthy individuals and three times as likely to sustain an injury during a fall. Unfortunately, current fall prevention techniques in place for cognitively healthy older adults are not as effective for those with dementia. The objective of this study was to examine balance differences between individuals of varying cognitive ability utilizing Easter Seals Adult Day Services. All study participants completed the Montreal Cognitive Assessment (MoCA). Clinical assessments were done in conjunction with static posturography data collection on a …

Phosphorus Adsorption Through Engineered Biochars Produced From Local Waste Products, Peter Ogonek

Honors Theses

Phosphorus contained in agricultural runoff is a major anthropogenic contributor to harmful algal blooms (HABs). Biochars are carbon-based materials produced from the pyrolysis of waste biomass that have the potential to amend soils and remediate inorganic and organic contaminants from water. Engineered biochars tailored to adsorb phosphorus from water could reduce the availability of the nutrient in agricultural runoff, reducing the size and frequency of HABs. This study observed the phosphorus adsorption properties of engineered biochars produced from two source materials, oak sawdust and cornstalk residue, and being unmodified, acid-rinsed, or loaded with magnesium prior to pyrolysis, creating acid-rinsed, unmodified, …

Drag Reduction Using Femtosecond Laser Surface Processing: Experimental Setup, Derek Wallin, Henry Ems, Craig Zuhlke, Dennis R. Alexander, George Gogos, Sidy Ndao

UCARE: Research Products

The experimental setup for developing a system to test the drag effects of different superhydrophorbicities. This is used to revise the current Moody Chart and redefine fluid drag in a pipe.

Fluid drag reduction is important in many applications such as reducing the power requirement to pump a fluid through a channel or pipe. The Center for Electro-Optics and Functionalized Surfaces (CEFS) at the University of Nebraska – Lincoln uses a femtosecond laser to functionalize 304 stainless Steel to become superhydrophilic or superhydrophobic The Processing produces microscale and nanoscale surface roughness that when treated with siloxanes becomes superhydrophobic. Small vortices …

Development Of A Robust Setup For The Study Of Wetting Characteristics Of Low Melting Point Metals, John D. Casias, Ethan Allan Davis, Sidy Ndao

UCARE: Research Products

• Energy use is very inefficient

• Approx. 60% rejected mostly in the form of waste heat

• Low melting point metals are promising for applications in thermal energy management, conversion, and storage

Texture Analysis Using The Neutron Diffraction Method On The Non Standardized Austenitic Steel Process By Machining,Annealing, And Rolling, Tri Hardi Priyanto, Parikin Parikin, Meijuan Li

Makara Journal of Technology

Austenitic steel is one type of stainless steel which is widely used in the industry. Many studies on austenitic stainless steel have been performed to determine the physical properties using various types of equipment and methods. In this study, the neutron diffraction method is used to characterize the materials which have been made from minerals extracted from the mines in Indonesia. The materials consist of a granular ferro-scrap, nickel, ferro-chrome, ferro-manganese, and ferro-silicon added with a little titanium. Characterization of the materials was carried out in three processes, namely: machining, annealing, and rolling. Experimental results obtained from the machining process …

A Preliminary Study Of The Relationship Between Complexity, Motivation, And Design Quality., Philip John Mountain

Electronic Theses and Dissertations

This collection of work comprises a preliminary study of the relationships between product complexity, design motivation, and design quality. Complexity, as it relates to the design process, is largely undefined and there exists no generally accepted method of measurement. This study applies an independent data set to a complexity measurement technique and develops complexity measurements at the pre and post design stages. Pre design is considered when design ideas are in formation and customer needs are being addressed. Post design is considered when a functional prototype is realized, manufacturing and assembly processes have been considered, and the product design is …

Ramifications Of Projectile Velocity On The Ballistic Dart Penetration Of Sand, Peter Anthony Sable

Master's Theses (2009 -)

With the advent of novel in-situ experimental measurement techniques, highly resolved quantitative observations of dynamic events within granular media can now be made. In particular, high speed imagery and digital analysis now allow for the ballistic behaviors of sand to be examined not only across a range of event velocities but across multiple length scales. In an attempt to further understand the dynamic behavior of granular media, these new experimental developments were implemented utilizing high speed photography coupled with piezo-electric stress gauges to observe visually accessible ballistic events of a dart penetrating Ottawa sand. Projectile velocities ranged from 100 to …

Application Of A Multi-Zone Model For The Prediction Of Species Concentrations In Rapid Compression Machine Experiments, David Wilson

Master's Theses (2009 -)

Accurate chemical kinetic models, which predict species evolution and heat release rates in chemically reactive systems, are essential for further advancements in fuel and combustion technology. An experimental facility that is widely used for evaluating the accuracy of kinetic models is a rapid compression machine (RCM), which creates a well-defined reaction environment by compressing a reactive mixture inside a chamber. Generally, RCM experiments are conducted in order to obtain ignition delay data. However, chemical speciation data provides greater insight into reaction pathways, and is therefore a more rigorous benchmark for validating kinetic models. In order for a chemical kinetic model …

Modeling And Investigation Of Refrigeration System Performance With Two-Phase Fluid Injection In A Scroll Compressor, Rui Gu

Master's Theses (2009 -)

Vapor compression cycles are widely used in heating, refrigerating and air-conditioning. A slight performance improvement in the components of a vapor compression cycle, such as the compressor, can play a significant role in saving energy use. However, the complexity and cost of these improvements can block their application in the market. Modifying the conventional cycle configuration can offer a less complex and less costly alternative approach. Economizing is a common modification for improving the performance of the refrigeration cycle, resulting in decreasing the work required to compress the gas per unit mass. Traditionally, economizing requires multi-stage compressors, the cost of …

Numerical Analysis For The Hemodynamics In Unruptured Cerebral Aneurysms, Hashem Mhd Hicham Alargha

Theses

A cerebral aneurysm is a vascular disorder characterized by abnormal focal dilation of a brain artery which is considered as a serious and potentially life-threatening condition. Cerebral aneurysms affect around 2%-5% of adults and they are fatal and can rupture with an overall mortality rate of more than 50%. Through computational fluid dynamics investigation, this study is offering a closer look into the initiation growth and rupture of cerebral aneurysms. Four focus points are studied in this thesis which are sensitivity analysis of blood viscosity in aneurysms, the effect of cerebral aneurysm size on wall stresses and strain, hazard effects …

Utilizing Tunable Signal Interference Control Topologies With Electromechanical Resonators, Bryce A. Geesey

Open Access Theses

Exploiting knowledge gained from previous investigations of channelized and trans-versal filters, signal interference filters use transmission line differences to generate transmission zeros through phase-shifted combinations of signals at the output of a device. The transmission lines used in these circuits are straightforward to design, but are limited to high-frequency signals (on the order of a few gigahertz) due to the necessity for spatial compactness and low loss. More recent studies have used electromechanical resonators to achieve phase shifting and quality factor improvements at slightly-lower frequencies. These concepts may prove useful if extended to micro- and nanoscale resonators.

To explore signal …