Engineering Commons^™

Total Cost Optimization For Contour Blasting In The Appalachia Region, Brett Christopher Jackson

Theses and Dissertations--Mining Engineering

This thesis recounts the study of contour blasting practices in the Appalachia coal region. Contour blasting practices vary widely and problems are often encountered. Several different sites were visited and contour blasting practices at each were studied. Based on the information gathered, a comprehensive plan was developed for blasting operations to follow and then was tested and compared to an example of blasting practices without use of the plan. The blasting practices were compared by examining monthly production rates as well as a time study to measure the efficiency a contour blast could be loaded and hauled away and a …

Analysis Of The Armps Database Using Flac3d; A Pillar Stability Comparison For Room And Pillar Coal Mines During Development, Ali Soltani

Theses and Dissertations--Mining Engineering

Designing a safe and economical mining activity is the main goal of every mine design engineer. With the rise of computer modeling in mine design there is a need for a standardized method to use geologic characterization of rocks in engineering design. In this research, first a review of empirical methods will be conducted and after that a step-by-step method is presented to adequately use FLAC3D, for development pillars, in room and pillar mine in development stage. ARMPS database is used to evaluate the FLAC3D model results. ARMPS database consists of 645 case study in room and pillar mines. 170 …

Static And Dynamic Discrete Element Modelling Of Slender Coal Pillars, Michael J. Raffaldi

Theses and Dissertations--Mining Engineering

Highwall mining is a mining method used in surface coal operations that involves driving a series of parallel entries into the exposed coal seam at the highwall face under an unsupported roof leaving behind a series of long, but very slender coal pillars. Highwall mining often occurs simultaneously with production blasting taking place in other areas of the mine. Although no failures of highwall pillars have been attributed to nearby blasting, numerical modelling presents an inexpensive means of investigating the possible effects of strong ground motion on the stability of these pillars. This thesis documents the development of a discrete …

Improved Understanding Of Coal Pillar Behavior And Bump Potential Through The Ground Response Curve, Kevin W. Harris

Theses and Dissertations--Mining Engineering

Continued depletion of easier coal reserves has necessitated development at deeper overburdens. At greater depth, operations often encounter more difficult ground conditions due to higher stresses and potential multiple seam interactions. Pillars which are left intact as the primary support mechanism experience an increase in loading. Mine design improvements are often incorporated to combat increased loads, principally by increasing pillar size. However, the potential for coal bumps, which are a rapid and violent failure of coal pillars, has increased due to these higher stresses and the use of larger width-to-height (W/H) ratio pillars.

Many efforts have been made to predict …

An Empirical Investigation Of Potential Relationships Between Organizational Culture Traits And Problem Solving Practices To Support Lean Transformations, Saket D. Fadnavis

Theses and Dissertations--Mechanical and Aerospace Engineering

Organizational culture can be defined as a set of values and behavior that contribute to the unique social and psychological environment of an organization. It is the major contributing factor in determining the progress of an organization towards the desired objectives. The importance of organizational culture for successful Lean transformation has been emphasized prior research.

Lean implementation is based on continuous improvement, the achievement of which is based on problem solving practices. For sustained continuous improvement, problem solving must be done in a repeatable and disciplined way. However, not many organizations follow a structured approach towards problem solving. Some preliminary …

Incorporating Dynamic Flame Behavior Into The Scaling Laws Of Wildland Fire Spread, Brittany A. Adam

Theses and Dissertations--Mechanical and Aerospace Engineering

A challenge for fire researchers is obtaining data from those fires that are most dangerous and costly. While it is feasible to instrument test beds, test plots, and small prescribed burns for research, it is uncommon to successfully instrument an active wildland fire. With a focus on very specific facets of wildland fire, researchers have created many unique models utilizing matchsticks, cardboard, liquid fuel, excelsior, plywood, live fuels, dead fuels, and wood cribs of different packing densities. Such scale models, however, only serve as valid substitutes for the full-scale system when all functional relations of the scale model are made …

Effect Of Heating And Ionization Of Four Atomizing Gases On The Spray Characteristics Of A High Volume Low Pressure Spray Atomizer, Anthony V. Adornato

Theses and Dissertations--Mechanical and Aerospace Engineering

The disintegration of a liquid jet emerging from a nozzle by a high speed gas stream has been under investigation of several decades. A result of the liquid jet disintegration is droplet formation. This process is referred to as atomization. Industrial applications use atomization as a method for applying coatings to substrates. It has been reported that the use of other atomizing gases instead of compressed plant air will positively affect paint droplet size distributions, spray patterns and finish qualities; furthermore, the ionization and heating of the atomizing gas was reported to positively affect finish qualities. Although ionization techniques have …

Mathematical Modeling For Platform-Based Product Configuration Considering Total Life-Cycle Sustainability, Tian Lan

Theses and Dissertations--Mechanical and Aerospace Engineering

Many companies are using platform-based product designs to fulfill the requirements of customers while maintaining low cost. However, research that integrates sustainability into platform-based product design is still limited. Considering sustainability during platform-based design process is a challenge because the total life-cycle from pre-manufacturing, manufacturing and use to post-use stages as well as economic, environmental and societal performance in these stages must be considered. In this research, an approach for quantifying sustainability is introduced and a mathematical model is developed for identifying a more sustainable platform. Data from life-cycle assessment is used to quantify environmental factors; criteria from the Product …

Experimental Investigation Of Wall Shear Stress Modifications Due To Turbulent Flow Over An Ablative Thermal Protection System Analog Surface, Jacob Helvey

Theses and Dissertations--Mechanical and Aerospace Engineering

Modifications were made to the turbulent channel flow facility to allow for fully developed rough quasi-2D Poiseuille flow with flow injection through one surface and flow suction through the opposing surface. The combination of roughness and flow injection is designed to be analogous to the flow field over a thermal protection system which produces ablative pyrolysis gases during ablation. It was found that the additional momentum through the surface acted to reduce skin friction to a point below smooth-wall behavior. This effect was less significant with increasing Reynolds number. It was also found that the momentum injection modified the wake …

Cfd Modeling Of Multiphase Counter-Current Flow In Packed Bed Reactor For Carbon Capture, Li Yang

Theses and Dissertations--Mechanical and Aerospace Engineering

Packed bed reactors with counter-current, gas-liquid flows have been considered to be applicable in CO₂ capture systems for post-combustion processing from fossil-fueled power production units. However, the hydrodynamics within the packing used in these reactors under counter-current flow has not been assessed to provide insight into design and operational parameters that may impact reactor and reaction efficiencies. Hence, experimental testing of a laboratory-scale spherical ball, packed bed with two-phase flow was accomplished and then a meso-scale 3D CFD model was developed to numerically simulate the conditions and outcomes of the experimental tests. Also, the hydrodynamics of two-phase flow in …

Effects Of Magnetic Field On The Shape Memory Behavior Of Single And Polycrystalline Magnetic Shape Memory Alloys, Ali S. Turabi

Theses and Dissertations--Mechanical and Aerospace Engineering

Magnetic Shape Memory Alloys (MSMAs) have the unique ability to change their shape within a magnetic field, or in the presence of stress and a change in temperature. MSMAs have been widely investigated in the past decade due to their ability to demonstrate large magnetic field induced strain and higher frequency response than conventional shape memory alloys (SMAs). NiMn-based alloys are the workhorse of metamagnetic shape memory alloys since they are able to exhibit magnetic field induced phase transformation. In these alloys, martensite and austenite phases have different magnetization behavior, such as the parent phase can be ferromagnetic and martensite …

An Experimental Method Of Measuring Spectral, Directional Emissivity Of Various Materials And Joule Heating, Robert Bickel

Theses and Dissertations--Mechanical and Aerospace Engineering

Emissivity is an important parameter in calculating radiative cooling of a surface. In experiments at the NASA Ames hypervelocity ballistic range, one of the main errors indicated in temperature measurements is the uncertainty of emissivity for the materials under investigation. This thesis offers a method for measuring emissivity of materials at elevated temperatures at the University of Kentucky. A test specimen which consists of different sample materials under investigation and a blackbody cavity was heated in a furnace to an isothermal condition at known temperature. The emitted thermal radiation was measured and the comparison of sample and blackbody radiation yielded …

Airborne Path Frequency Based Substructuring Method And Its Applications, Rui He

Theses and Dissertations--Mechanical and Aerospace Engineering

Frequency based substructuring (FBS) is routinely used to model structural dynamics. It provides a framework for connecting structural subsystems together, assessing path contributions, determining the effect of mount modification, and identifying inverse forces. In this work, FBS methods are extended to include acoustic subsystems and connecting pipes and ducts. Connecting pipes or ducts are modeled using the transfer matrix approach which is commonly used for modeling mufflers and silencers below the plane wave cutoff frequency. The suggested approach is validated using boundary element method (BEM) simulation. Applications of the procedure include determining airborne path contributions, the effect of treating ducts …

A Framework For Sustainable Material Selection For Multi-Generational Components, Ryan T. Bradley

Theses and Dissertations--Mechanical and Aerospace Engineering

The early stages of a product’s design are a critical time for decisions that impact the entire life-cycle cost. Product designers have mastered the first generation; however, they currently do not have the ability to know the impact of their decisions on the multi-generational view. This thesis aims at closing the gap between total life-cycle information and the traditional design process in order to harbor sustainable value creation among all stakeholders involved. A framework is presented that uses a combination of a life-cycle costing methodology and an evolutionary algorithm in order to achieve a sustainability assessment for a true multi-generational …

Modeling Of Spallation Phenomenon In An Arc-Jet Environment, Raghava Sai Chaitanya Davuluri

Theses and Dissertations--Mechanical and Aerospace Engineering

Space vehicles, while entering the planetary atmosphere, experience high loads of heat. Ablative materials are commonly used for a thermal protection system, which undergo mass removal mechanisms to counter the heat rates. Spallation is one of the ablative processes, which is characterized by the ejection of solid particles from the material into the flow. Numerical codes that are used in designing the heat shields ignore this phenomenon. Hence, to evaluate the effectiveness of spallation phenomenon, a numerical model is developed to compute the dynamics and chemistry of the particles. The code is one-way coupled to a CFD code that models …

High Temperature Flow Solver For Aerothermodynamics Problems, Huaibao Zhang

Theses and Dissertations--Mechanical and Aerospace Engineering

A weakly ionized hypersonic flow solver for the simulation of reentry flow is firstly developed at the University of Kentucky. This code is the fluid dynamics module of known as Kentucky Aerothermodynamics and Thermal Response System (KATS). The solver uses a second-order finite volume approach to solve the laminar Navier– Stokes equations, species mass conservation and energy balance equations for flow in chemical and thermal non-equilibrium state, and a fully implicit first-order backward Euler method for the time integration. The hypersonic flow solver is then extended to account for very low Mach number flow using the preconditioning and switch of …

Shape Memory Behavior Of Single Crystal And Polycrystalline Ni-Rich Nitihf High Temperature Shape Memory Alloys, Sayed M. Saghaian

Theses and Dissertations--Mechanical and Aerospace Engineering

NiTiHf shape memory alloys have been receiving considerable attention for high temperature and high strength applications since they could have transformation temperatures above 100 °C, shape memory effect under high stress (above 500 MPa) and superelasticity at high temperatures. Moreover, their shape memory properties can be tailored by microstructural engineering. However, NiTiHf alloys have some drawbacks such as low ductility and high work hardening in stress induced martensite transformation region. In order to overcome these limitations, studies have been focused on microstructural engineering by aging, alloying and processing.

Shape memory properties and microstructure of four Ni-rich NiTiHf alloys (Ni50.3Ti29.7Hf20, Ni50.7Ti29.3Hf20, …

Development And Validation Of Finite Element Approaches To Determine The Insertion Loss Of Louvered Terminations Including Parametric Investigations, Huangxing Chen

Theses and Dissertations--Mechanical and Aerospace Engineering

Louvers are employed at the ends of HVAC ducts to direct airflow, provide weather protection, and attenuate noise. This details two finite element approaches that can be used to assess the acoustic attenuation from a louvered termination. In the first approach, plane wave propagation is assumed inside of a duct with a non-reflective source. On the receiver side, a baffled termination is assumed and the radiation condition is simulated using a non-reflective boundary condition called an automatically matched layer. In the second approach, a short aperture is placed between two infinite acoustic spaces. On the source side, a diffuse acoustic …

Joint Formation Under Severely Altered Background Atmosphere In Controlled Atmosphere Brazing Of Aluminum, Cheng-Nien Yu

Theses and Dissertations--Mechanical and Aerospace Engineering

Adverse changes of background atmosphere in a brazing chamber cause qualitative and quantitative deterioration of joint formation in an aluminum brazing process. This study offers an insight into the adverse effects with gradually adjusted atmospheric conditions in terms of oxygen and humidity levels. Corresponding responses of the molten clad flow and the joint formation upon resolidification vs. atmospheric conditions are documented by comparative tests involving self-fluxing and surface-fluxing brazing sheets: 1) in situ and in real time study of the onset of melting, clad flow, and joint formation, and 2) inclined wedge-tee mating tests for brazeability assessment. The surface-fluxing brazing …

Computational Modeling Of Cardiac Biomechanics, Amir Nikou

Theses and Dissertations--Mechanical and Aerospace Engineering

The goal of this dissertation was to develop a realistic and patient-specific computational model of the heart that ultimately would help medical scientists to better diagnose and treat heart diseases. In order to achieve this goal, a three dimensional finite element model of the heart was created using magnetic resonance images of the beating pig heart. This model was loaded by the pressure of blood inside the left ventricle which was measured by synchronous catheterization. A recently developed structurally based constitutive model of the myocardium was incorporated in the finite element solver to model passive left ventricular myocardium. Additionally, an …

Determination Of Isolator Transfer Matrix And Insertion Loss With Application To Spring Mounts, Shishuo Sun

Theses and Dissertations--Mechanical and Aerospace Engineering

Transmissibility is the most common metric used for isolator characterization. However, engineers are becoming increasingly concerned about energy transmission through an isolator at high frequencies and how the compliance of the machine and foundation factor into the performance. In this study, the transfer matrix approach for isolator characterization is first reviewed. Two methods are detailed for determining the transfer matrix of an isolator using finite element simulation. This is accomplished by determining either the mobility or impedance matrix for the isolator and then converting to a transfer matrix. One of the more useful metrics to characterize the high frequency performance …

Radiative Conductivity Analysis Of Low-Density Fibrous Materials, Nima Nouri

Theses and Dissertations--Mechanical and Aerospace Engineering

The effective radiative conductivity of fibrous material is an important part of the evaluation of the thermal performance of fibrous insulators. To better evaluate this material property, a three-dimensional direct simulation model which calculates the effective radiative conductivity of fibrous material is proposed. Two different geometries are used in this analysis.

The simplified model assumes that the fibers are in a cylindrical shape and does not require identically-sized fibers or a symmetric configuration. Using a geometry with properties resembling those of a fibrous insulator, a numerical calculation of the geometric configuration factor is carried out. The results show the dependency …

A Subsystem Identification Approach To Modeling Human Control Behavior And Studying Human Learning, Xingye Zhang

Theses and Dissertations--Mechanical and Aerospace Engineering

Humans learn to interact with many complex dynamic systems such as helicopters, bicycles, and automobiles. This dissertation develops a subsystem identification method to model the control strategies that human subjects use in experiments where they interact with dynamic systems. This work provides new results on the control strategies that humans learn.

We present a novel subsystem identification algorithm, which can identify unknown linear time-invariant feedback and feedforward subsystems interconnected with a known linear time-invariant subsystem. These subsystem identification algorithms are analyzed in the cases of noiseless and noisy data.

We present results from human-in-the-loop experiments, where human subjects in- teract …

Inkjet Printing: Facing Challenges And Its New Applications In Coating Industry, Sadegh Poozesh

Theses and Dissertations--Mechanical and Aerospace Engineering

This study is devoted to some of the most important issues for advancing inkjet printing for possible application in the coating industry with a focus on piezoelectric droplet on demand (DOD) inkjet technology. Current problems, as embodied in liquid filament breakup along with satellite droplet formation and reduction in droplet sizes, are discussed and then potential solutions identified. For satellite droplets, it is shown that liquid filament break-up behavior can be predicted by using a combination of two pi-numbers, including the Weber number, We and the Ohnesorge number, Oh, or the Reynolds number, Re, and the Weber number, …

Low-Order Discrete Dynamical System For H2-Air Finite-Rate Combustion Process, Wenwei Zeng

Theses and Dissertations--Mechanical and Aerospace Engineering

A low-order discrete dynamical system (DDS) for finite-rate chemistry of H₂-air combustion is derived in 3D. Fourier series with a single wavevector are employed to represent dependent variables of subgrid-scale (SGS) behaviors for applications to large-eddy simulation (LES). A Galerkin approximation is applied to the governing equations for comprising the DDS. Regime maps are employed to aid qualitative determination of useful values for bifurcation parameters of the DDS. Both isotropic and anisotropic assumptions are employed when constructing regime maps and studying bifurcation parameters sequences. For H₂-air reactions, two reduced chemical mechanisms are studied via the DDS. …

Development Of Multifunctional Shape Memory Polymer And Shape Memory Polymer Composites, Sesha Spandana Pulla

Theses and Dissertations--Mechanical and Aerospace Engineering

Shape memory polymers (SMPs) are an emerging class of active polymers that can be used on a wide range of reconfigurable structures and actuation devices. The present study comprehensively examines the unconstrained shape recovery abilities of an epoxy-based SMP. In doing so, epoxy based SMP is synthesized and thermo-mechanically characterized. Results show that the present SMP exhibits excellent shape recoveries under unconstraint conditions, for a range of fixing strains and temperatures. Additionally, the stress-strain behavior of the SMP is determined to be nonlinear, finite deformation at all regions. The strain energy based models have been used to capture the complicate …

Role Based Hedonic Games, Matthew Spradling

Theses and Dissertations--Computer Science

In the hedonic coalition formation game model Roles Based Hedonic Games (RBHG), agents view teams as compositions of available roles. An agent's utility for a partition is based upon which role she fulfills within the coalition and which additional roles are being fulfilled within the coalition. I consider optimization and stability problems for settings with variable power on the part of the central authority and on the part of the agents. I prove several of these problems to be NP-complete or coNP-complete. I introduce heuristic methods for approximating solutions for a variety of these hard problems. I validate heuristics on …

Design Of A Scalable Path Service For The Internet, Mehmet O. Ascigil

Theses and Dissertations--Computer Science

Despite the world-changing success of the Internet, shortcomings in its routing and forwarding system have become increasingly apparent. One symptom is an escalating tension between users and providers over the control of routing and forwarding of packets: providers understandably want to control use of their infrastructure, and users understandably want paths with sufficient quality-of-service (QoS) to improve the performance of their applications. As a result, users resort to various “hacks” such as sending traffic through intermediate end-systems, and the providers fight back with mechanisms to inspect and block such traffic.

To enable users and providers to jointly control routing and …

Optimal Uses Of Biomass Resources In Distributed Applications, Joshua J. Jackson

Theses and Dissertations--Biosystems and Agricultural Engineering

Biomass production is spatially distributed resulting in high transportation costs when moving dedicated biomass crops and crop residues. A multifaceted approach was taken to address this issue as the low bulk and energy density of biomass limits transportation efficiency. Two systems were analyzed for the conversion of biomass into a denser feedstock applicable to on-farm use. Pelletization was able to densify the material into a solid fuel. Using a pilot scale flat ring pellet mill, the density of the material was able to be increased to at least 4.4 times that of uncompressed material. Pellet durability was found to be …

Characterization Of Two Biochars Derived From Horse Muck And Their Ability To Reduce Pathogen Transport In Soil, David Griffith

Theses and Dissertations--Biosystems and Agricultural Engineering

Biochars have been created and characterized from a variety livestock manure biomass including poultry, dairy, and swine. However, no research has been conducted on the physical and chemical makeup of biochar pyrolyzed from horse muck. Two horse muck derived biochars containing either straw (HS) or woodchip (HW) bedding were pyrolyzed at 700°C and characterized for their physical and chemical properties. Tests revealed both biochars had high alkalinity, moderate specific conductivity, and low surface area as compared to other biochars in the literature. HS contained more mineral structures than HW. Scanning electron microscopy presented differences in particle shape, size, and presence …