Engineering Commons^™

Ultrasonic Concentration Of Microorganisms, Samuel J. Mullins

Theses and Dissertations--Biosystems and Agricultural Engineering

Concentration of microorganisms from a sample volume would increase the limits of detection of samples used for rapid-detection methods. Rapid detection methods are is advantageous for the food industry to rapidly test for bacteria in order release products on a timely basis. Ultrasonic concentration was considered a promising method for manipulation of microorganisms. An ultrasonic chamber consisting of parallel piezoceramic discs with a reticulated polyurethane foam mesh was used to concentrate Saccharomyces cerevisiae yeast and Escherichia coli bacteria. The concentration of yeast was seen to increase by 200% (from 8.0 x 10⁴ cells mL^-1 to 2.4 x 10 …

Assessment Of Conductivity Sensors Performance For Monitoring Mined Land Discharged Waters And An Evaluation Of The Hydrologic Performance Of The Guy Cove Stream Restoration Project, Travis Pritchard Maupin

Theses and Dissertations--Biosystems and Agricultural Engineering

The surface mining method of mountaintop removal has been shown to adversely affect the water quality and hydrologic characteristics of downstream regions. Based on recent scientific literature, the U.S. EPA issued guidance on the specific conductivity (EC25ºC) of waters discharged from mined lands in the Appalachian Coal Belt Region stating that these waters should have an EC25ºC less than 300-500 μS cm-1. Hence, accurately measuring EC25ºC levels of mine discharged waters has significant implications. Furthermore, the development of reclamation techniques that positively impact the hydrological and water quality aspects of valley fill (VF) discharge is needed. To tackle these questions, …

Evaluation Of Transitions For Testing Agricultural Ventilation Fans With The Fan Assessment Numeration System (Fans), Igor Moreira Lopes

Theses and Dissertations--Biosystems and Agricultural Engineering

The Fan Assessment Numeration System (FANS) is an improved air velocity traverse method for measuring in situ fan performance. The FANS has been widely used, but variations of its test procedure are commonly employed to accommodate physical or operational barriers encountered in the field. This laboratory study evaluated the use of transitions to connect a 1.37m FANS unit to two smaller fans (1.22m and 0.91m diameter) and one 1.37m diameter fan. Tests were conducted with the FANS unit positioned on both intake and discharge sides of the fans. Three different transition angles (30^o, 45^o and 60^{o …}

Development Of A Noncontact Sensor For Monitoring Milk Coagulation And Cutting Time Prediction In Cheese Making, Molly D. Craft-Jenkins

Theses and Dissertations--Biosystems and Agricultural Engineering

Cheese products are manufactured more consistently and with better quality if the curd cutting time can be consistently selected. An optical sensor that accurately predicts cutting time has been developed for large cheese vats, but the initial cost of these sensors makes them uneconomical for small artisan cheese manufacturers. The small artisan cheese vats require an inexpensive sensor technology that can be implemented simply. The initial cost of purchasing a sensor and installing these sensors plus the need for a computational program for implementing the algorithm make this technology excessively expensive for these smaller cheese manufacturers. The objective of this …

Evaluation Of Separation Method Additives For The Recovery Of Bacteria From Food Matrices, Jennifer Leanne Frederick

Theses and Dissertations--Biosystems and Agricultural Engineering

The microbiological testing of foods is a well-established science. Due to the severity of foodborne pathogen illnesses, the widespread use and implementation of rapid detection methods in food testing labs is increasingly important. The first step for successful testing is sampling. Surfactants have been highly used in food microbiology, but there is not much, if any, published research about the use of fatty alcohols and chemical dispersants as aids in microbial separation. The microbial extraction efficiency of Escherichia coli K12 and Listeria innocua from hot dogs, spinach, and milk was measured using chemical additives (surfactants, fatty alcohols, and a chemical …

Computational Tools For Improving Route Planning In Agricultural Field Operations, Rodrigo S. Zandonadi

Theses and Dissertations--Biosystems and Agricultural Engineering

In farming operation, machinery represents a major cost; therefore, good fleet management can have a great impact on the producer’s profit, especially considering the increasing costs of fuel and production inputs in recent years. One of the tasks to be accomplished in order to improve fleet management is planning the path that the machine should take to cover the field while working. Information such as distance traveled, time and fuel consumption as well as agricultural inputs wasted due to off-target-application areas are crucial in the path planning process. Parameters such as field boundary size and geometry, machine total width as …

Evaluating The Effectiveness Of Weep Berm Systems For Treating Runoff From A Horse Muck Composting Operation, Ross L. Guffey

Theses and Dissertations--Biosystems and Agricultural Engineering

Two contour weep berms systems were designed and implemented to evaluate their performance at mitigating water quantity problems from a horse muck composting operation. The field-scale study focused on the hydrologic response of a standard contour weep berm and a modified contour weep berm. The modified contour weep berm incorporated a woodchip trench upgradient of a typical standard contour weep design. Monitoring occurred from July 2011 through spring 2012. Eight storm events produced measureable runoff for the standard contour weep berm; however, only five storm events produced measurable runoff for the modified contour weep berm. The largest storm event occurred …

Multiwall Carbon Nanotube Arrays For Thermal Interface Enhancement, Darrell Keith Etheredge

Theses and Dissertations--Mechanical and Aerospace Engineering

High performance/small package electronics create difficult thermal issues for integrated circuits. Challenges exist at material interfaces due to interfacial contact resistances. Multiwall carbon nanotube (MWCNT) arrays are considered to be excellent candidates for use as thermal interface materials (TIMs) due to outstanding thermal/mechanical properties. In this work, MWCNT array TIMs are analyzed in aluminum and carbon fiber composites via flash diffusivity analysis. The effect of TIM thickness, areal/bulk density, surface cleanliness, and volumetric packing fraction; along with the effect of substrate finish and interfacial contact pressure on thermal performance are analyzed. Trends show the best TIMs possess low thickness, high …

Development Of Strategies To Minimize The Release Of Trace Elements From Coal Waste Sources, Mohammad Rezaee

Theses and Dissertations--Mining Engineering

To assess strategies aimed at minimizing the release of trace elements and the impact of disposal of coal waste materials on the environment, two long-term leaching experiments of up to five months duration were performed using waste materials from two plants cleaning high and low sulfur bituminous coal. The tests evaluated the mobility of major trace elements under different disposal scenarios: (i) a static leaching test designed to simulate the quiescent conditions encountered by coal waste material stored under water in a stable impoundment, and (ii) a dynamic test to simulate waste materials exposed to the atmosphere, either in variable …

The Development Of A Predictive Probability Model For Effective Continuous Learning And Improvement, Michael Abbot Maginnis

Theses and Dissertations--Mechanical and Aerospace Engineering

It is important for organizations to understand the factors responsible for establishing sustainable continuous improvement (CI) capabilities. This study uses learning curves as the basis to examine learning obtained by team members doing work with and without the application of fundamental aspects of the Toyota Production System. The results are used to develop an effective model to guide organizational activities towards achieving the ability to continuous improve in a sustainable fashion.

This research examines the effect of standardization and waste elimination activities supported by systematic problem solving on team member learning at the work interface and system performance. The results …

Simulation And Experimental Validation Of Airborne And Structure-Borne Noise Transmission In Hvac Plenums, Srinivasan Ramalingam

Theses and Dissertations--Mechanical and Aerospace Engineering

This research demonstrates the usage of numerical acoustics to model sound and vibrational energy propagation in HVAC ducts and plenums. Noise and vibration in HVAC systems propagates along three primary paths that can be classified as airborne direct, airborne indirect and structure-borne. The airborne direct path was simulated using acoustic FEM with special boundary conditions to handle the diffuse acoustic field loading and the baffled termination. The insertion loss for a number of different plenum geometries was compared to published measurement results. Results were in good agreement both below and above the cutoff frequency. Additionally, the airborne indirect path, often …

Temperature And Strain Controlled Optimization Of Stabilization Of Polyacrylonitrile Precursor Fibers, Mark Parr Taylor

Theses and Dissertations--Mechanical and Aerospace Engineering

Carbon fiber is one of the leading materials for high strength and modulus, and light weight applications. Improvements in carbon fiber properties are directly dependent on all aspects of manufacture, especially the process of stabilization. Therefore, it is the goal of this thesis to study the effects of the temperature and strain profile of the stabilization process, and the resulting carbon fiber tensile properties. In addition, the precursor fibers used were spun under two different draw ratios, to study the effects of the spinning parameters. Results indicated through DMA studies that completeness of stabilization reactions can be gauged by the …

Cryogenic Machining And Burnishing Of Az31b Magnesium Alloy For Enhanced Surface Integrity And Functional Performance, Zhengwen Pu

Theses and Dissertations--Mechanical and Aerospace Engineering

Surface integrity of manufactured components has a critical impact on their functional performance. Magnesium alloys are lightweight materials used in the transportation industry and are also emerging as a potential material for biodegradable medical implants. However, the unsatisfactory corrosion performance of Mg alloys limits their application to a great extent. Surface integrity factors, such as grain size, crystallographic orientation and residual stress, have been proved to remarkably influence the functional performance of magnesium alloys, including corrosion resistance, wear resistance and fatigue life.

In this dissertation, the influence of machining conditions, including dry and cryogenic cooling (liquid nitrogen was sprayed to …

Is Densified Biomass Fuel From Agro-Forestry Waste A Sustainable Energy Option?, William A. Linnig Iii

Theses and Dissertations--Mechanical and Aerospace Engineering

Raw biomass material is bulky, high in void fraction, and very low in transportation efficiency. Furthermore, biomass dissipates quickly in harsh environments of high heat furnaces because of its relatively low calorific value (BTU/lb) and has grinding or size degradation properties highly dissimilar from commonly-used fossil fuels like coal. Therefore, the development of transformational technologies are necessary to convert raw biomass into high-value and useful products of high hardness and calorific value without requiring excessive process energy.

This thesis investigates the sustainability of densified biomass fuels. In addition, a procedure that converts raw biomass from agro/forest industry waste into a …

Specified Motion And Feedback Control Of Engineering Structures With Distributed Sensors And Actuators, Amirhossien Ghasemi

Theses and Dissertations--Mechanical and Aerospace Engineering

This dissertation addresses the control of flexible structures using distributed sensors and actuators. The objective to determine the required distributed actuation inputs such that the desired output is obtained. Two interrelated facets of this problem are considered. First, we develop a dynamic-inversion solution method for determining the distributed actuation inputs, as a function of time, that yield a specified motion. The solution is shown to be useful for intelligent structure design, in particular, for sizing actuators and choosing their placement. Secondly, we develop a new feedback control method, which is based on dynamic inversion. In particular, filtered dynamic inversion combines …

Simulation Of Whistle Noise Using Computational Fluid Dynamics And Acoustic Finite Element Simulation, Jiawei Liu

Theses and Dissertations--Mechanical and Aerospace Engineering

The prediction of sound generated from fluid flow has always been a difficult subject due to the nonlinearities in the governing equations. However, flow noise can now be simulated with the help of modern computation techniques and super computers. The research presented in this thesis uses the computational fluid dynamics (CFD) and the acoustic finite element method (FEM) in order to simulate the whistle noise caused by vortex shedding. The acoustic results were compared to both analytical solutions and experimental results to better understand the effects of turbulence models, fluid compressibility, and wall boundary meshes on the acoustic frequency response. …

Cryogenic Burnishing Of Co-Cr-Mo Biomedical Alloy For Enhanced Surface Integrity And Improved Wear Performance, Shu Yang

Theses and Dissertations--Mechanical and Aerospace Engineering

The functional performance of joint implants is largely determined by the surface layer properties in contact. Wear/debris-induced osteolysis and aseptic loosening has been identified as the major cause of failure of metal-on-metal joint implants. A crucial requirement for the long-term stability of the artificial joint is to minimize the release of debris particles.

Severe plastic deformation (SPD) processes have been used to modify the surface integrity properties by generating ultrafine, or even nano-sized grains and grain size gradients in the surface region of many materials. These fine grained materials often exhibit enhanced surface integrity properties and improved functional performance (wear …

Geometric Control Of Inflatable Surfaces, Isaac John Scherrer

Theses and Dissertations--Mechanical and Aerospace Engineering

High precision inflatable surfaces were introduced when NASA created the ECHO 1 Balloon in 1960. The experiment proved that inflatable structures were a feasible alternative to their rigid counterparts for high precision applications. Today inflatable structures are being used in aviation and aerospace applications and the benefits of using such structures are being recognized. Inflatable structures used in high precision structures require the inflatable surfaces to have controllable and predictable geometries. Many applications such as solar sails and radar reflectors require the surface of such structures to have a uniform surfaces as such surfaces improve the efficiency of the structure. …

A Filter-Forcing Turbulence Model For Large Eddy Simulation Incorporating The Compressible "Poor Man's" Navier--Stokes Equations, Joshua Strodtbeck

Theses and Dissertations--Mechanical and Aerospace Engineering

A new approach to large-eddy simulation (LES) based on the use of explicit spatial filtering combined with backscatter forcing is presented. The forcing uses a discrete dynamical system (DDS) called the compressible ``poor man's'' Navier--Stokes (CPMNS) equations. This DDS is derived from the governing equations and is shown to exhibit good spectral and dynamical properties for use in a turbulence model. An overview and critique of existing turbulence theory and turbulence models is given. A comprehensive theoretical case is presented arguing that traditional LES equations contain unresolved scales in terms generally thought to be resolved, and that this can only …

Experimental Benchmarking Of Surface Textured Lip Seal Models, Wei Li

Theses and Dissertations--Mechanical and Aerospace Engineering

A thorough investigation on the existing hydrodynamic lubrication theories and the reverse pumping theories for the conventional lip seal is conducted. On that basis, the algorithms and the methods used in the numerical modeling of the conventional lip seal are modified and applied to the study of the lip seal running against surface textured shafts. For each step of the study, the numerical model is benchmarked against the experimental results. Important physical mechanisms which explain the reverse pumping ability of the triangular surface structures are revealed. Meanwhile, the accuracy of the numerical model is tested. In general, the numerical simulation …

A New Metric-Based Lca Method For Assessing The Sustainability Performance Of Metallic Automotive Components, Xiangxue Zhang

Theses and Dissertations--Mechanical and Aerospace Engineering

This thesis presents a new metric-based Life-cycle Assessment (LCA) method for assessing the sustainability performance of metallic automotive components. The unique feature of this research work include the development and use of a metrics-based product sustainability index (ProdSI) methodology by considering the total life-cycle approach and the triple bottom line (TBL) with the 6R methodology. It has been shown that the manufactured product’s sustainability performance can be comprehensively assessed using this new methodology. The major focus of this research is the integration of the 6R activities (Reduce, Reuse, Recycle, Recover, Redesign and Remanufacture). Four life-cycle stages of the …

Transport Phenomena Associated With Liquid Metal Flow Over Topographically Modified Surfaces, Wen Liu

Theses and Dissertations--Mechanical and Aerospace Engineering

Brazing and soldering, as advanced manufacturing processes, are of significant importance to industrial applications. It is widely accepted that joining by brazing or soldering is possible if a liquid metal wets the solids to be joined. Wetting, hence spreading and capillary action of liquid metal (often called filler) is of significant importance. Good wetting is required to distribute liquid metal over/between the substrate materials for a successful bonding.

Topographically altered surfaces have been used to exploit novel wetting phenomena and associated capillary actions, such as imbibitions (a penetration of a liquid front over/through a rough, patterned surface). Modification of surface …

Finite Element Analysis Of Cancellous Bone, Lucas T. Wilkerson

Theses and Dissertations--Mechanical and Aerospace Engineering

A variety of pathologies exist which increase the likelihood of bone fracture. Present methods for determining the fracture risk of a specific patient are based exclusively on the amount of bone present. While the quantity of bone tissue is correlated with strength, it neglects to account for bone’s intricate microarchitecture. To assess the effect of bone quality on strength, a methodology was developed for the structural analysis of cancellous bone biopsies. Thirty biopsies were selected from a pre-existing biopsy bank, and scanned using a SCANCO µCT-40 at a resolution of 30 microns. Cortical bone was removed from the resulting three-dimensional …

Design And Flight Testing Of A Warping Wing For Autonomous Flight Control, Edward Brady Doepke

Theses and Dissertations--Mechanical and Aerospace Engineering

Inflatable-wing Unmanned Aerial Vehicles (UAVs) have the ability to be packed in a fraction of their deployed volume. This makes them ideal for many deployable UAV designs, but inflatable wings can be flexible and don’t have conventional control surfaces. This thesis will investigate the use of wing warping as a means of autonomous control for inflatable wings. Due to complexities associated with manufacturing inflatable structures a new method of rapid prototyping deformable wings is used in place of inflatables to decrease cost and design-cycle time. A UAV testbed was developed and integrated with the warping wings and flown in a …

Low Reynolds Number Flow Field Modification Via Travelling Wave Actuation Of A Vertically Aligned Wire Array Surface, John C. Calhoun

Theses and Dissertations--Mechanical and Aerospace Engineering

Experiments were conducted to observe the effects of an active wire surface on low-Reynolds number Poiseuille flow. The objective was to evaluate the feasibility of actuating piezoelectric nanowires into a travelling wave motion in order to reduce wall shear stress in turbulent flows. Studies have shown that travelling wave motions introduced into the bounding wall of turbulent flow can reduce wall shear stress by disrupting the formation of drag-inducing coherent vortical structures. A Reynolds number scaled flow facility was designed to represent the near-wall region of turbulent flow. A wire surface was installed in the bounding wall and dynamically actuated …

Root Locus Techniques With Nonlinear Gain Parameterization, Brandon Wellman

Theses and Dissertations--Mechanical and Aerospace Engineering

This thesis presents rules that characterize the root locus for polynomials that are nonlinear in the root-locus parameter k. Classical root locus applies to polynomials that are affine in k. In contrast, this thesis considers polynomials that are quadratic or cubic in k. In particular, we focus on constructing the root locus for linear feedback control systems, where the closed-loop denominator polynomial is quadratic or cubic in k. First, we present quadratic root-locus rules for a controller class that yields a closed-loop denominator polynomial that is quadratic in k. Next, we develop cubic root-locus rules …

Aerodynamics And Control Of A Deployable Wing Uav For Autonomous Flight, Michael Thamann

Theses and Dissertations--Mechanical and Aerospace Engineering

UAV development and usage has increased dramatically in the last 15 years. In this time frame the potential has been realized for deployable UAVs to the extent that a new class of UAV was defined for these systems. Inflatable wing UAVs provide a unique solution for deployable UAVs because they are highly packable (some collapsing to 5-10% of their deployed volume) and have the potential for the incorporation of wing shaping. In this thesis, aerodynamic coefficients and aileron effectiveness were derived from the equations of motion of aircraft as necessary parameters for autonomous flight. A wind tunnel experiment was performed …

Nanocrystals Of Chemotherapeutic Agents For Cancer Theranostics: Development And In Vitro And In Vivo Evaluation, Christin P. Hollis

Theses and Dissertations--Pharmacy

The majority of pharmacologically active chemotherapeutics are poorly water soluble. Solubilization enhancement by the utilization of organic solvents often leads to adverse side effects. Nanoparticle-based cancer therapy, which is passively targeted to the tumor tissue via the enhanced permeation and retention effect, has been vastly developed in recent years. Nanocrystals, which exist as crystalline and carry nearly 100% drug loading, has been explored for delivering antineoplastic agents. Additionally, the hybrid nanocrystal concept offers a novel and simple way to integrate imaging agents into the drug crystals, enabling the achievement of theranostics. The overall objective of this dissertation is to formulate …

Improving Model Performance Using Season-Based Evaluation, Misgana Muleta

Civil and Environmental Engineering

Computer models have become vital decision-making tools in many areas of science and engineering including water resources. However, models should be properly evaluated before use to improve the likelihood of making sound decisions based on their results. The model evaluation technique practiced today in hydrology assumes that model parameters are season insensitive and attempts to identify “optimal” values that would describe watershed behavior during dry and wet seasons. This assumption could compromise accuracy of model predictions. This study demonstrates performance improvement that would be achieved when a season-based model evaluation approach is pursued. A global sensitivity analysis (SA) model has …

Optical Mode Pattern Study Of Gan Based Leds With And Without Nanoscale Top Grating, Gregory Chavoor

Electrical Engineering

This study analyzes optical confinement factor and light emitting mode order for three different GaN LEDs: a conventional LED, thin Film LED, and thin Film LED with a photonic crystal (PhC) grating. For the first structure, we increase the thickness of Al_xGa_1-xN from 0 to 600nm, alter the x composition in Al_xGa_1-xN from 0.05 to 0.2 in steps of 0.05, and adjust the p-GaN and n-GaN thicknesses each from 0 to 200nm. For the second structure, we alter the n-GaN substrate thickness from 300-1000nm in steps of 100nm and 1000-4000nm in steps …