Engineering Commons^™

Geophysics-Based Ground Control And Excavation Design Methodology Based On Acceptable Damage, Jorge Romana Giraldo

Theses and Dissertations--Civil Engineering

This dissertation is structured around a novel conceptual framework for designing deep excavation retaining systems and using geophysical data to estimate the mechanical response of soft soil deposits. It begins with presenting an approach to design excavation retaining walls based on limiting damage to adjacent infrastructure. In this approach, the damage is defined based on critical distortions of an idealized laminate beam model used for representing the adjacent building deformations. The wall and support elements of the support system are then designed such that the system yields the limiting ground deformations. The resulting excavation support system limits damage to adjacent …

Induced Travel Demand: Measuring The Contribution Of Additional Lane Miles On The Increase In U.S. Vehicle Miles Traveled From 1980 To 2019, Brandon Ivanchak

Theses and Dissertations--Civil Engineering

Induced travel demand is the effect of increasing the amount of vehicle miles traveled because of an increase in roadway capacity. It is explained by the idea that increasing capacity makes driving on those roads more desirable, thereby causing more people to use them. In1962, Robert Downs postulated that “On urban commuter expressways, peak hour traffic congestion rises to meet maximum capacity,” referring to this as the law of peak hour traffic congestion. Since then, there have been ongoing debates about the effectiveness and environmental impact of roadway expansion projects, and efforts to quantify induced demand to inform those debates. …

A Computational Exploration Of The Scandate Cathode Surface, Shankar Miller-Murthy

Theses and Dissertations--Chemical and Materials Engineering

The exact surface configuration of scandate cathodes has been a point of contention for the materials community for a long time. Without proper understanding of it and the related structures and emission mechanisms, scandate cathodes remain patchy and unreliable emitters. Thus, density functional theory techniques were applied to various potential surface arrangements and found that there are several low-energy surfaces with low work functions that incorporate a scandium interlayer between tungsten and oxygen or otherwise have a scandium-on-tungsten structure. Furthermore, it was discovered that adding a monolayer of scandium directly to a tungsten surface is surprisingly favorable, thermodynamically. While none …

Pitch-Based Carbon Fiber Derived From Coal Extract Liquids, Cierra Danielle Crowe

Theses and Dissertations--Chemical and Materials Engineering

Limited coal coking operations and the use of coal-tar pitch as a binding agent in the production of metallurgical anodes has led to a limited availability of coal tar pitch for carbon fiber products. This has sparked interest in utilizing non-metallurgical coal-based liquids as an alternative to traditional coal tar from metcoke operations. This can be achieved by low severity solvent extraction, with heavy aromatic solvents, to produce coal liquids that act as precursor to pitch-based carbon fiber. This thesis aims to establish the processing and determine the impact of utilizing coal liquids to produce carbon fiber. In this work …

Green-Route Synthesis Of Halide Perovskite Materials And Their Optoelectronic Properties, Xiaobing Tang

Theses and Dissertations--Chemical and Materials Engineering

Colloidal semiconductor quantum dots (QDs), also called as nanocrystals (NCs), are a class of functional materials with extraordinary properties, which are different from their bulk counterparts and benefit from their exclusive quantum confinement (size) effect. Semiconductor exhibits the quantum confinement effect when the characteristic size of the semiconductor is comparable to or smaller than the de Broglie wavelength of the electron wave function and/or the exciton Bohr diameter of the bulk semiconductor. In recent years, metal halide perovskite NCs, as next-generation semiconductor materials for lighting and display, have aroused a wide attention due to their excellent optoelectronic properties. However, traditional …

Development Of Univariate And Multivariate Forecasting Models For Methane Gas Emissions In Underground Coal Mines, Juan Diaz

Theses and Dissertations--Mining Engineering

Methane gas management continues to be a challenge concerning underground coal mine safety and productivity worldwide despite the extraordinary effort of the mining industry, governmental agencies, and academia to develop new technologies to monitor and control methane gas emissions more efficiently. The risk of hazardous methane gas concentrations in underground environments cannot be underestimated. Statistical data for the last 100 years indicate that around 80% of the accidents and 90% of the fatalities in the underground coal mining industry in the US were related to methane gas explosions.

Modern underground mine operations monitor and evaluate atmospheric parameters such as barometric …

Laptop Recycling Case Study: Estimating The Contained Value And Value Recovery Process Feasibility Of End-Of-Life Consumer Electronics, Zebulon Hart

Theses and Dissertations--Mining Engineering

Work has been done to establish, through the development and use of novel assay techniques and analysis metrics, the contained value of a sampling of laptop computers (as an analog for myriad e-waste sources). This work has conceptualized e-waste as an alternative to geologic-origin complex metallic ores and has likewise evaluated the feasibility of value recovery from e-waste sources in a similar manner to an ore. The application of conventional and novel mineral separation techniques to e-waste recycling processes has been evaluated and positive results are demonstrated. Further, this work has demonstrated the ability to identify the presence of base …

Parametric Numerical Analysis Of Inclined Coal Pillars, Robin Flattery

Theses and Dissertations--Mining Engineering

Pillars are used as the primary support structures for underground mining to maintain stability by supporting the over laying strata. In the case of horizontal seams, the pillars are typically subjected to axial loading due to the weight of the overburden and/or abutment stresses, while in the case of inclined seams they are subjected to oblique loading due to both the vertical and horizontal in-situ stress. Over the years numerous studies have been completed on square and rectangular pillars in horizontal seams that have resulted in several pillar stability equations and criteria. However very few studies are available with respect …

Investigation Into, & Analysis Of Temperature & Strain Data For Coal Mine Seal Material During Curing, Stephanus Jaco Van Den Berg

Theses and Dissertations--Mining Engineering

On Monday, January 2, 2006, an underground explosion occurred at the Sago Mine WV, resulting in the death of 12 miners and seriously injury to one miner. On Saturday, May 20, 2006, an underground explosion occurred at the Darby Mine No.1 KY, resulting in five miner’s deaths and one miner’s injury.

The explosion of methane gas and coal dust result in many fatalities in the coal mining industry.

The coal mining industry uses mine seals to optimize the ventilation network. Those structures are designed not only to direct the air appropriately, but also, they should be capable of withstanding some …

Development Of Univariate And Multivariate Forecasting Models For Methane Gas Emissions In Underground Coal Mines, Juan Diaz

Theses and Dissertations--Mining Engineering

Methane gas management continues to be a challenge concerning underground coal mine safety and productivity worldwide despite the extraordinary effort of the mining industry, governmental agencies, and academia to develop new technologies to monitor and control methane gas emissions more efficiently. The risk of hazardous methane gas concentrations in underground environments cannot be underestimated. Statistical data for the last 100 years indicate that around 80% of the accidents and 90% of the fatalities in the underground coal mining industry in the US were related to methane gas explosions.

Modern underground mine operations monitor and evaluate atmospheric parameters such as barometric …

Modeling Human Control Behavior In Command-Following Tasks, Sajad Koushkbaghi

Theses and Dissertations--Mechanical and Aerospace Engineering

Humans interact with a variety of complex dynamic systems on a daily basis. However, they are often the lesser understood component of human-in-the-loop (HITL) systems. In this dissertation, we present the results of two HITL experiments to investigate the control strategies that humans use when performing command-following tasks. The first experiment is designed to investigate the control strategies that humans use to interact with nonlinear dynamic systems. Two groups of human subjects interact with a dynamic system and perform a command-following task. One group interacts with a linear time-invariant (LTI) dynamic system and the other group interacts with a Wiener …

Energy And Economic Modeling Of Stillage Dewatering Processes In Kentucky Bourbon Distilleries, William Brennan

Theses and Dissertations--Mechanical and Aerospace Engineering

Stillage is a byproduct of alcohol distillation and must be managed in all distilleries to sustain operations. In the United States, fuel ethanol plants typically convert all stillage into Dried Distillers’ Grains with Solubles (DDGS). This process and its variations are well known. Typical stillage management approaches are not well known, however, for the Kentucky bourbon industry. A survey of stillage management approaches in operational bourbon distilleries was conducted. Process modeling was performed to evaluate the energy and economic considerations of the available stillage dewatering methods for a 7 Million Original Proof Gallon (MMOPG) distillery. Monte Carlo simulations were performed …

Quantitative Methods For Total Lifecycle Risk Likelihood And Impact Assessment In Sustainable Product Design Decision Making, Christian Enyoghasi

Theses and Dissertations--Mechanical and Aerospace Engineering

Sustainable products promise significant economic, environmental, and societal benefits. Numerous methods are available for use during the new product development process to identify alternate product designs that optimize sustainability performance. Once any such design is selected and the product is launched, many uncertainties are likely to affect its performance over the total lifecycle. Such uncertainties give rise to risks that can influence the overall product sustainability performance. However, comprehensive quantitative methods to evaluate the likelihood or the impact of different risks to enable sustainable product design decision making are lacking.

This research aims to address this gap by developing a …

In-Situ Characterization Of Surface Quality In Γ-Tial Aerospace Alloy Machining, David Adeniji

Theses and Dissertations--Mechanical and Aerospace Engineering

The functional performance of critical aerospace components such as low-pressure turbine blades is highly dependent on both the material property and machining induced surface integrity. Many resources have been invested in developing novel metallic, ceramic, and composite materials, such as gamma-titanium aluminide (γ-TiAl), capable of improved product and process performance. However, while γ-TiAl is known for its excellent performance in high-temperature operating environments, it lacks the manufacturing science necessary to process them efficiently under manufacturing-specific thermomechanical regimes. Current finish machining efforts have resulted in poor surface integrity of the machined component with defects such as surface cracks, …

Radiative Conductivity Estimation Using Direct Approach For Fibrous Materials, Mohammad Khaleel

Theses and Dissertations--Mechanical and Aerospace Engineering

During planetary entry, space vehicles encounter high loads of thermal energy which requires a thermal protection system. Ablative thermal protection systems are usually made out of fibrous materials that exhibit internal radiation. In order to model the internal radiation response of a thermal protection system one should obtain proper radiative properties as well as thermal properties. The objective of this work is to provide a method that solves for the solid/gas thermal conductivity. Which can be used in coupled detailed radiative analysis.

Keywords: radiative conductivity, fibrous materials, radiative transfer, thermal protection system, P1 approximation, Finite Volume method.

A Decoupled Engineering Methodology For Accurate Prediction Of Ablative Surface Boundary Conditions In Thermal Protection Systems, Justin Cooper

Theses and Dissertations--Mechanical and Aerospace Engineering

The main objective of the present work is to demonstrate a method for prediction of aerothermal environments in the engineering design of hypersonic vehicles as an alternative to the current heritage method. Flat plate and stagnation point boundary layer theory require multiple assumptions to establish the current engineering paradigm. Chief among these assumptions is the similarity between mass and heat transfer. Origins of these assumptions are demonstrated and their relationship to conservative engineering design is analyzed, as well as conditions where they possibly break down. An alternative approach for assessing aerothermal environments from the fluid domain is presented, which permits …

Formation Control With Bounded Controls And Collision Avoidance: Theory And Application To Quadrotor Unmanned Air Vehicles, Zachary S. Lippay

Theses and Dissertations--Mechanical and Aerospace Engineering

This dissertation presents new results on multi-agent formation control and applies the new control algorithms to quadrotor unmanned air vehicles. First, this dissertation presents a formation control algorithm for double-integrator agents, where the formation is time varying and the agents’ controls satisfy a priori bounds (e.g., the controls accommodate actuator saturation). The main analytic results provide sufficient conditions such that all agents converge to the desired time-varying relative positions with one another and the leader, and have a priori bounded controls (if applicable). We also present results from rotorcraft experiments that demonstrate the algorithm with time-varying formations and bounded controls. …

The Effects Of Reference-Command Preview On The Strategies That Humans Use In Command-Following Tasks, Amelia J. S. Sheffler

Theses and Dissertations--Mechanical and Aerospace Engineering

This thesis presents results from an experiment in which 22 human subjects each interact with a dynamic system 40 times over a one-week period. For each interaction, a subject performs a command-following task, where the reference command is the same for all 22 subjects but different on each trial. The subjects are divided into 2 groups of 11 subjects. One group performs the command-following task without reference-command preview. The other group is provided with 1-s preview of the reference command. The experimental results are used to examine the effects of reference-command preview. For the group with 1-s reference-command preview, the …

Small-Satellite Attitude Control Using Sinusoidal Actuator Motion: Experiments On The International Space Station, K. Ryan Lush

Theses and Dissertations--Mechanical and Aerospace Engineering

In this work, we design, build, and test two 1.25U CubeSats. These small satellites were deployed on the International Space Station to perform attitude control experiments in microgravity. These CubeSats use an oscillating-mass actuation system for attitude control as opposed to traditional flywheels. Each CubeSat uses 3 pairs of servomotors to oscillate masses about 3 orthogonal axes. The servomotors have strict rotational stroke limits. Thus, they cannot spin continually. To oscillate each pair of masses, the angle of each servomotor is commanded using signals that are continuous and piecewise sinusoidal with amplitudes that do not violate the servomotor stroke constraints. …

Kentucky Re-Entry Universal Payload System (Krups): Hypersonic Re-Entry Flight, John Daniel Schmidt

Theses and Dissertations--Mechanical and Aerospace Engineering

The Kentucky Re-entry Universal Payload System (KRUPS) is a small capsule designed as a technology testbed for re-entry experiments. For its first incarnation, KRUPS has been designed to test Thermal Protection Systems (TPS) and instruments in re-entry flights. Because of the unique environment a vehicle undergoes during re-entry, there is a high-demand for experimental data from re-entry experiments. KRUPS has been developed at the University of Kentucky (UK) over the past seven years to meet this demand. After completing sub-orbital campaigns, the first KRUPS hypersonic re-entry mission was attempted. The mission involved building three 11-inch diameter capsules each outfitted with …

Experimental Comparison Of Two Sampled-Data Adaptive Control Algorithms For Rejecting Sinusoidal Disturbances, William Grayson Woods

Theses and Dissertations--Mechanical and Aerospace Engineering

We review two adaptive control algorithms that address the problem of rejecting sinusoids with known frequencies that act on an unknown asymptotically stable linear time-invariant system. We present modifications to the algorithms that address the problems of sensor noise and actuator saturation. We demonstrate the effectiveness of the algorithms and compare the performance of the algorithms via numerical simulation and experimental testing.

Numerical And Scaling Study On Application Of Inkjet Technology To Automotive Coating, Masoud Arabghahestani Dr.

Theses and Dissertations--Mechanical and Aerospace Engineering

A thorough literature review identified lack of precision control over quality of droplets generated by the currently available industrial sprayers and a growing need for higher quality droplets in the coating industry. Particularly, lack of knowledge and understanding in continuous inkjets (CIJ) and drop-on-demand (DOD) technologies is identified as significant. Motivated by these needs, this dissertation is dedicated to computational fluid dynamics (CFD) and scaling studies to improve existing inkjet technologies and develop new designs of efficient coating with single and/or multiple piezoelectric sensors to produce on-demand droplets. This dissertation study aims at developing a new DOD type coating technology, …

In-Situ Characterization Of Burr Formation In Finish Machining Of Inconel 718, Hamzah M. Zannoun

Theses and Dissertations--Mechanical and Aerospace Engineering

One of the undesirable byproducts that occur during the machining process is the development of burrs, which are defined as rough excess material that forms around the geometric discontinuities of a part. Burrs are especially problematic because they have negative impacts across the triple bottom line: economic, environmental, societal. For one, they are expensive to remove because the deburring process is entirely manual and requires skill. Further, burr material is typically discarded which is adding to the already mounting waste generated from machining such as in coolant and chip disposal. Lastly, there are many societal implications, such as operator injury …

Peridynamic Material Correspondence Models: Bond-Associated And Higher-Order Formulations, Wailam Chan

Theses and Dissertations--Mechanical and Aerospace Engineering

Peridynamic material correspondence model is able to incorporate material constitutive models directly from classical continuum mechanics theory. However, conventional correspondence model faces two major technical issues for its application to practical problems. The first is the material instability, which results severe oscillations in the predicted displacement fields. The second issue is the length scale effects of materials mechanical behavior at low length scales. This research journey mainly consists of three stages. The first two stages of this research journey focus on the development of the bond-associated peridynamic material correspondence model to inherently remove the material instability. The last stage focuses …

Shape Memory Behavior Of Nitihf Alloys Fabricated By Laser Powder Bed Fusion, Guher Pelin Toker

Theses and Dissertations--Mechanical and Aerospace Engineering

NiTiHf-based alloys have emerged as potential materials for applications requiring high transformation temperatures (> 100 °C) with high strength and work output. Currently, it is challenging to produce complex shapes of these materials with tailored shape memory properties or reduce the material waste from machining operations given the cost of these materials. Additive manufacturing via Laser Powder Bed Fusion (L-PBF) represents an attractive way to fill this gap by producing unique geometries from powder-based feedstock. In this method, process parameters such as laser power, scanning speed, hatch spacing and energy density play significant roles in controlling the mechanical behavior and …

Experimental Investigation Of Roughness And Blowing Effects Over Ablator-Like Surfaces, Colby Borchetta

Theses and Dissertations--Mechanical and Aerospace Engineering

Two separate experiments using PIV were carried out to investigate the effects of
roughness and blowing over surfaces geometrically similar to ablation materials used for atmospheric re-entry. The first, water tunnel experiments, employed a dimpled surface similar to AVCOAT, while the second set was completed in a wind tunnel with a material similar to PICA. For the first set, the flow with blowing becomes destabilized, and more disorganized. The blowing disrupts the relatively simple vorticity shedding process and significantly modifies momentum transport via interaction of detached structures. Flow structure and their modifications were examined with a sPOD analysis. The focus …

Formation Control With Collision Avoidance For Fixed-Wing Unmanned Air Vehicles With Speed Constraints, Christopher Heintz

Theses and Dissertations--Mechanical and Aerospace Engineering

Advances in the miniaturization of powerful electronic components and motors, the democratization of global navigation satellite systems (GNSS), and improvements in the performance, safety, and cost in lithium batteries has led to the proliferation of small and relatively inexpensive unmanned aerial vehicles (UAVs). Many of these UAVs are of the multi-rotor design, however, fixed-wing designs are often more efficient than rotary-wing aircraft, leading to a reduction in the power required for a UAV of a given mass to stay airborne. Autonomous cooperation between multiple UAVs would enable them to complete objectives that would be difficult or impossible for a single …

The Response Of Beef Cattle To Disturbances From Unmanned Aerial Vehicles (Uavs), Gabriel Abdulai

Theses and Dissertations--Biosystems and Agricultural Engineering

Unmanned aerial vehicles (UAVs) are increasingly becoming common in animal agriculture. However, research regarding the impact of UAV disturbance on animal wellbeing is lacking or limited. The goal of this study was to investigate the effect of UAV flights on beef cattle by measuring cattle heart and movement rate when introduced to single or multiple UAV flights. A total of 16 -18 crossbred beef heifers were introduced to different flights patterns at between 5 and 9 m above ground level (AGL) at approximately 1 to 2 m/s horizontal velocity for 4 weeks with flights repeated 3 days per week. Results …

Lignin Valorization Via Reductive Depolymerization Using Promoted Nickel Catalysts And Sub- And Supercritical Methanol, Julia Parker

Theses and Dissertations--Biosystems and Agricultural Engineering

While lignin has been regarded as the most promising renewable feedstock for the sustainable manufacture of aromatic compounds, lignin valorization is necessary to improve the economic viability of biorefineries. Reductive catalytic fractionation (RCF), which combines delignification and lignin depolymerization into a single stage while maintaining the structure and integrity of the cellulose component, has evolved as an effective method for processing biomass. The ability of Cu and Fe to promote the performance of a 20% Ni/alumina catalyst when converting native lignin to alkylphenols by RCF in sub- and supercritical methanol was tested. The effectiveness of lignin extraction as measured by …

Implications To Tap And Stream Water Chemistry Due To Variations In Sampling Locations And Watershed Land Use, Dayana Rodriguez

Theses and Dissertations--Biosystems and Agricultural Engineering

The Kentucky River Basin, which is in the Eastern Kentucky Coal Field region, is a rural region with sparse population distribution and a history of water quality impairments. The long history of mining activity in the Commonwealth has not only left a mark on the area’s economy, but it has also shaped the environment. Changes in land use from forested areas to surface mining have been shown to significantly change water chemistry and hydrology. To date, there is limited information regarding the potential exposure and introduction of heavy metals and sulfate entering rural water treatment plants, resulting in a notable …