Engineering Commons^™

Modification And Evaluation Of Continuous Roll Prediction Model For Front Drive Mowers, Xinyan Wang

Doctoral Dissertations

The recently approved ASAE Standard S547 “Tip-Over Protective Structure (TOPS) for Front Wheel Drive Turf and Landscape Equipment” addressed a continuous roll prediction model for Roll-Over Protective Structure (ROPS) design. The existing model described in this Standard did not take into account the influence of the mower deck on the rollover behavior. In order to evaluate the accuracy of the original model, according to the ASAE S547 requirement, a 4.05 meters long and 3.42 meters wide slope of 35 degrees was constructed at the University of Tennessee. Lateral upset tests for Deere F925 front drive mower with regular and inverted …

Differential-Algebraic Approach To Speed And Parameter Estimation Of The Induction Motor, Mengwei Li

Doctoral Dissertations

This thesis considers a differential-algebraic approach to estimating the speed and rotor time constant of an induction motor using only the measured terminal voltages and currents. It is shown that the induction motor speed satisfies both a second-order and a third-order polynomial equation whose coefficients depend the stator voltages, stator currents, and their derivatives. Further, it is shown that as long as the stator electrical frequency is nonzero, the speed is uniquely determined by these polynomials. The speed so determined is then used to stabilize a dynamic (Luenberger type) observer to obtain a smoothed speed estimate. With full knowledge of …

Thermal And X-Ray Analysis On The Origin Of Double Melting Phenomena Of Poly(L-Lactic Acid) Films, Xiaoyun Ling

Doctoral Dissertations

Thermal analysis is one of the most commonly used techniques to characterize the structure and properties of semicrystalline polymers. Unfortunately, the interpretation of thermal events is not always straightforward, but can be quite complicated. However, the complexity involved is often overlooked, leading to erroneous or, at least, questionable results and interpretations. In the present study we carry out an extensive investigation of the thermal behavior of poly(L-lactic acid), PLLA, films prepared under a wide range of crystallization conditions, including isothermal and non-isothermal crystallization from both the glassy state and the melt. The primary techniques used were differential scanning calorimetry (DSC), …

High-Temperature Low-Cycle-Fatigue And Crack-Growth Behaviors Of Three Superalloys: Hastelloy ® X, Haynes ® 230, And Haynes ® 188, Yulin Lu

Doctoral Dissertations

Extensive smooth-bar low-cycle-fatigue (LCF) and fatigue crack growth (FCG) experiments on three solid-solution-strengthened superalloys HASTELLOY X, HAYNES 230, and HAYNES 188 have been conducted at 816 and 927 C. Limited tests were run at 649 C, 871 C, and 982 C to study the temperature effect. The LCF tests were performed under a total-strain-range-control mode at Solar Turbines Inc., Metcut Research Inc., and The University of Tennessee (UT). The FCG tests were done under both the constant-load-range and constant-stress-intensity-factor-range modes at Westmoreland Testing Inc. and UT. Various hold times were imposed at the maximum strain or load in both the …

Isolation And Thermodynamic Characterization Of Aminoglycoside Nucleotidyltransferase (2″)-Ia, Roger Edward Wright

Doctoral Dissertations

Aminoglycoside nucleotidyltransferase(2″)-Ia is one of the most important aminoglycoside-modifying enzymes. Because of the difficulties in isolating this enzyme with a high level of purity, very little work has been reported for this enzyme. A procedure for obtaining this enzyme with a purity level of greater than 95% from inclusion bodies was developed. The optimal conditions for isolating ANT(2″) were solubilizing the inclusion bodies in 8 M urea followed by direct dilution of the enzyme into 0.1 M Tris-HCl pH 8.5, 0.2 M KCl, 0.4 ML-arginine and 5 mM reduced glutathione at 4°C. The determination of an effective method of obtaining …

A Proposed Framework For Simultaneous Optimization Of Evacuation Traffic Distribution And Assignment, Fang Yuan

Doctoral Dissertations

In the conventional evacuation planning process, evacuees are assigned to fixed destinations based mainly on the criterion of geographical proximity. However, such pre-specified destinations (OD table) almost always lead to sub-optimal evacuation efficiencies due to uncertain road conditions such as congestion, road blockage, and other hazards associated with the emergency. By relaxing the constraint of assigning evacuees to pre-specified destinations, a one-destination evacuation (ODE) concept has the potential of greatly improving the evacuation efficiency. A framework for simultaneous optimization of evacuation traffic distribution and assignment is therefore proposed in this study. Based on the concept of ODE, the optimal destination …

Analysis Of Vehicle Use Patterns During Military Field Exercises To Identify Potential Roads, Chunxia Wu

Doctoral Dissertations

Military training is an intensive land use and can cause negative environmental effects. Many studies conducted under Integrated Training Area Management (ITAM) for quantifying the impact resulted from the military training exercise found that off-road vehicular activities during training exercises cause the major impact to the training land. Vehicle land use patterns at a certain location affect the impact severity: concentrated and repeated traffic create more serious damage to the land compared to the dispersed offroad vehicle movements. Those areas heavily disturbed by off-road traffic may require a longer period of time or special treatments for the land to return …

Evaluation Of Heavy-Duty Diesel Vehicle Emissions During Cold-Start And Steady-State Idling Conditions And Reduction Of Emissions From A Truck-Stop Electrification Program, James A. Calcagno

Doctoral Dissertations

Cold-start and extended-idling emissions of carbon monoxide (CO), oxides of nitrogen (NOx) and particulate matter (PM) were measured from 24, class-8B, heavy-duty diesel vehicles (HDDV8B) using portable emission monitoring equipment. The ratio of nitrogen dioxide (NO₂) to NOx and the ratio of PM_2.5 to total PM were reported. Truck model years ranged from 1992 to 2004. All vehicles were tested in the field during summer and fall months under ambient environmental conditions at low (600-800 rpm) and high (1000 rpm) engine idling speeds with the truck cab air-conditioner operating at “on” and “off” modes. Sampling data thus …

Health Risk Assessment Posed By The Mobile Source Air Toxics On An Urban To Regional Area, Luis Alonso Díaz Robles

Doctoral Dissertations

Air toxics are important health concern. The purpose of this research was to develop a protocol to predict exposure concentrations of air toxics and inhalation cancer and noncancer risk that come from different gasoline and diesel-fueled sources. The protocol was developed by linking the U.S. EPA’s Models-3/CMAQ model as the exposure model and toxicological and epidemiological evidence functions. The NEI version 3 for the year 1999 was used in this analysis for point, area, and non-road sources, whereas NMIM was used to create the on-road emissions. The year 2003 was used for meteorological data and as reference to compare the …

Liquid Crystals Confined In Nanoporous Silica, Yang Gao

Doctoral Dissertations

Confinement has a nontrivial effect on a condensed matter system due to the finite size effect, the surface effect and the induced disorder. Different techniques such as calorimetric measurement, dielectric spectroscopy, dynamic light scattering, X-ray scattering and quasi-elastic neutron scattering have been widely used to study this important topic. Confined liquid crystals (LCs) have attracted great attention in particular because they are a soft system and their physical properties are more easily affected by the geometrical confinement (entropic) effect and the surface interaction (energetic) effect. In this paper, we study the phase transitions and dynamic behavior of LCs, 5CB and …

Adaptive Nonlinear Optimization Methodology For Installed Capacity Decisions In Distributed Energy/Cooling Heat And Power Applications., Carl Randolph Hudson

Doctoral Dissertations

Evaluation of potential cooling, heating and power (CHP) applications requires an assessment of the operations and economics of a particular system in meeting the electric and thermal demands of a specific end-use facility. Given the electrical and thermal load behavior of a facility, the tariff structure for grid-supplied electricity, the price of primary fuel (e.g., natural gas), the operating strategy and characteristics of the CHP system, and an assumed set of installed CHP system capacities (e.g., installed capacity of prime mover and absorption chiller), one can determine the cost of such a system as compared to reliance solely on traditional, …

The Rrnat/Rdna Ratio As A Measure Of Nitrite Oxidizing Activity, Shawn A. Hawkins

Doctoral Dissertations

A bench scale nitrification reactor (BSNR) containing nitrite oxidizing bacteria (NOB) of the genus Nitrobacter (» 1 × 10¹⁰/L; 5 - 22% of bacteria) was used to assess the ribosomal RNA transcript (rRNAt) to ribosomal RNA gene (rDNA) ratio as an in-situ nitrite oxidizing activity metric. A quantitative PCR detection system was developed that amplified a 143 base pair sequence within the Nitrobacter spp. 16S - 23S intergenenic spacer region. The resulting real-time PCR (rDNA) and real-time RT-PCR (rRNAt) assays were specific, accurate, and sensitive, requiring three replicate nucleic acid extracts to reliably detect a true 2-fold concentration …

The Effect Of Ultrasonic Vibration On The Solidification Of Light Alloys, Xiaogang Jian

Doctoral Dissertations

This exposition presents the novel thermodynamical and microstructural modification to light alloys, such as aluminum alloys and magnesium alloys, by ultrasonic vibrations during their solidification processes. Ultrasonic vibration has proven to be effective in controlling columnar dendritic structure, reducing the size of equiaxed grains, and under some conditions, producing globular non-dendritic grains. Despite this, the solidification process under the effect of ultrasonic vibration was not clear. Not only was there no such research on how ultrasonic vibration affected its solidification thermodynamically, but also its effects on the as-cast microstructure, including the primary fcc phase, the eutectics, and the secondary phases, …

Experimental, Theoretical, And Device Application Development Of Nanoscale Focused Electron-Beam-Induced Deposition, Steven Jeffrey Randolph

Doctoral Dissertations

To elucidate the effects of beam heating in electron beam-induced deposition (EBID), a Monte-Carlo electron-solid interaction model has been employed to calculate the energy deposition profiles in bulk and nanostructured SiO₂. Using these profiles, a finite element model was used to predict the nanostructure tip temperatures for standard experimental EBID conditions. Depending on the beam energy, beam current, and nanostructure geometry, the heat generated can be substantial. This heat source can subsequently limit the EBID growth by thermally reducing the mean stay time of the precursor gas. Temperature dependent EBID growth experiments qualitatively verified the results of the …

Suppliers Evaluation And Selection: A Comprehensive Model To Minimize The Risk Associated With Quality And Delivery, Ammar Mohamed Aamer

Doctoral Dissertations

This research focuses on one of the main steps in outsourcing, supplier
evaluation and selection. The main contributions of this research were twofold.
First, best practices in the supplier’s value stream were identified that directly or
indirectly impact a supplier’s quality and delivery. Second, a comprehensive
supplier evaluation and selection model was developed based on the value
stream concept to minimize the risk associated with two very critical supplierselection factors, quality and on-time delivery.

A survey was conducted to identify best practices. The outcome of the survey
was used to develop a computer based supplier evaluation model, which could
be …

Manufacturing System And Supply Chain Analyses Related To Product Complexity And Sequenced Parts Delivery, Hui Sun

Doctoral Dissertations

Mixed model assembly has been widely used in many industries. It is applied in order to effectively deal with increasing product complexity. Sequencing and resequencing on a mixed-model assembly line is also complicated by high product complexity. To improve the performance of a mixed-model assembly system and the supply chain, one can develop efficient sequencing rules to address sequencing problems, and manage product complexity to reduce its negative impact on the production system. This research addresses aspects of sequence alteration and restoration on a mixed-model assembly line for the purpose of improving the performance of a manufacturing system and its …

A Methodology For Solving The Equations Arising In Nonlinear Parameter Identification Problems: Application To Induction Machines, Kaiyu Wang

Doctoral Dissertations

This dissertation presents a method that can be used to identify the parameters of a class of systems whose regressor models are nonlinear in the parameters. The technique is based on classical elimination theory, and it guarantees that the solution for the parameters which minimize a least-squares criterion can be found in a finite number of steps. The proposed methodology begins with an input-output linear overparameterized model whose parameters are rationally related. After making appropriate substitutions that account for the overparameterization, the problem is transformed into a nonlinear least-squares problem that is not overparameterized. The extrema equations are computed, and …

Evaluation Of Engineering Plastic For Rollover Protective Structure Mounting, Robert Stephen Comer

Masters Theses

The agricultural industry has one of the highest fatality rates of any industry in the U. S. This death rate is largely due to deaths caused by roll over accidents while on agricultural vehicles. The addition of a Rollover Protective Structure (ROPS) has aided in lowering these high fatality rates on full-size tractors. Studies have shown that death rates have been reduced by as much as 98% with the addition of rollover protective structures. However, a large number of older tractors still do not utilize a ROPS. This is due to the difficulty of designing and creating a mounting structure. …

Comparison Of Microscopic Modalities For The 3d Model Reconstruction Of Nanodevices, Christopher Robert Kammerud

Masters Theses

As manufacturing capabilities push nanotechnology to smaller and smaller scales, novel inspection schemes must be developed to ensure product quality. The objective of our research was to implement, refine, and compare 3D reconstruction algorithms that could aid manufacturers in their ability to visualize and inspect nanodevices. Data was collected from three different microscopes: the atomic force microscope (AFM), the scanning electron microscope (SEM), and the laser scanning confocal microscope (LSCM). For each of these microscopes, a specific algorithm was implemented to generate 3D models from the raw microscope data. Scans from the AFM microscope give range information similar to laser …

A Statistical Based Model To Manage Perishable Goods Within A Cold Supply Chain, Amanda Rhiana Hicks

Masters Theses

"Cold chain" management, the management of a temperature sensitive supply chain, has its own particular set of logistical challenges and issues when compared to a non-temperature sensitive supply chain. Current supply chain management techniques and tools that are utilized today in industry do not take this unique set of challenges into account. This thesis will focus on how using a model that has been built upon the theories of statistical process control techniques that does take the challenges into account, when monitoring and evaluating in-transit shipment of perishable goods throughout the cold supply chain, can assist in continuously improving the …

Experimental Aerodynamic Analysis Of A Wing-Flap System With Delta Vortex Generators, Charles Roy Mcconnell

Masters Theses

The principle idea upon which the use of vortex generators (VGs) is based has been to control flow separation. The characteristic of VGs has been used to improve lift and alter the stall characteristics of aircraft and has been a relatively common practice for many years. Due to the seemingly limitless range of VG geometries and arrangements, which are largely dependant upon the desired aerodynamic performance, there has been a broad investigation into VG application.

The purpose of this experimental investigation has been to collect data to be used to establish the effects of various delta shaped vortex generators (delta-VGs) …

Temperature Control Of The Online Rheological Sensor, Larry Scott Spencer

Masters Theses

Rheometers are devices that can be used to measure the rheological properties of polymers. Online rheometers test for rheological properties during a polymer process. Real-time rheological data would eliminate any time delays that accompany off-line rheometers and would provide the feedback information needed for tighter polymer process control. A real-time control system would eliminate the need for an offline rheometer to analyze polymer product properties, thus saving both time and money.

The Online Rheological Sensor was used to estimate the shear and elongational viscosities of a polymer from measured variables during processing. The Online Rheological Sensor was mounted on a …

Biomimetic Membranes Realized With Arrays Of Carbon Nanofibers, Eric Hullander

Masters Theses

A microfluidic device with imbedded nanoporous membranes, constructed using a novel nanostructured material, was designed, built, modeled, and tested. The membranes were shown to be modular, and by adsorbing monodisperse latex spheres to the fibrous membrane, the pore size could be controlled. A mathematical model of the device was developed based on several existing fluidic models for transport through fibrous materials, and an image processing algorithm was designed to extract the hydrodynamic properties of the device from a series of scanning electron micrographs based on the existing hydrodynamic models. A series of experiments were performed using fluorescent microscopy to quantify …

Enhancing System-On-Chip Verification Using Embedded Test Structures, Wei Jiang

Masters Theses

In this project, we designed and implemented a System-on-Chip platform with embedded test structures. The baseline platform consists of a Leon2 CPU, AMBA on-chip bus, and an Advanced Encryption Standard decryption module. Reconfigurable test logic blocks were embedded to form the test structure that can be used in post-silicon debug and verification.

The System-on-Chip platform was designed at the register transistor level and implemented in an 180nm CMOS process. Test logic instrumentation was done with DAFCA, Inc. (Design Automation for Flexible Chip Architecture) pre-silicon tools. The design was then synthesized using the Synopsys Design Compiler and placed and routed using …

A Numerical Study Of Curved Labyrinth Seals For Steam Turbines, Sricharan Kishore Ayyalasomayajula

Masters Theses

A numerical experiment has been conducted to study and evaluate the structural behavior of newly designed labyrinth seals. Structural analysis was performed to understand, evaluate and compare new seals with a baseline straight seal that is typical of commonly used seals in steam turbines. New configurations of labyrinth seal knives were developed for use in steam turbines [17]. The main objective of this study is to develop a better understanding of selected various labyrinth seals that may be configured to minimize the steam leakage and reduce seal interactions with the shaft. Computational fluid dynamic modeling of the various configurations, from …

Flight Testing Quadeye The First Night Vision Helmet Mounted Cueing System For Fixed Wing Jet Aircraft, Timothy Ghannon Burton

Masters Theses

In 2002 the United States Navy introduced helmet mounted cueing systems (HMCS) into tactical jet operations. As aircrews have become more reliant on their HMCS the requirement for a night vision capable cueing system has risen to the forefront of HMCS technology. One proposed solution to this requirement was Quadeye. Quadeye is a wide-angle (100deg field of view) four cathode-ray tube system with injected Joint Helmet Mounted Cueing video. The Navy flew 8 evaluation sorties from March to August 2005, in the F-18 A-F fighter aircraft. The goal of this limited scope effort was to answer four questions:

1. Does the …

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Viscosity Measurement Technique By Merging Liquid Drops Aboard The International Space Station, Daniel Aaron Lehman

Masters Theses

The efforts reported in this thesis has been to analyze the data from two "Fluid Merging Viscosity Measurement" experiments in order to validate this as a viable method for measuring the viscosity of fluids with known surface tensions. This method involves simultaneously using a numerical analysis code and experimental data to produce matching curves of contact radius versus time and from that a determination of viscosity. Two experiments that were performed, used different liquids (glycerin and 125 Poise silicon oil) and different size ratios between the two drops ( 1 to 1 and O. 3 3 to 1 respectively). The …

Topology Optimization Of Carbon Nanotube Reinforced Polymer Damping Structures, Seshadri Mohan Varma Damu

Masters Theses

Topology optimization has been successfully used for improving vibration damping in constrained layer damping structures. Reinforcing carbon nanotubes in a polymer matrix greatly influence the mechanical properties of the polymer. Such nanotube-reinforced polymers (NRP) can be used to further enhance the damping properties of the constrained layer structures. In this work, topology optimization is performed on constrained damping layer structures using NRP in order to maximize the loss factor for the first resonance frequency of the base beam. In addition to the material fractions of the NRP and elastic material, the volume fraction of the nanotubes in the polymer is …

Optimization Of Dsss Receivers Using Hardware-In-The-Loop Simulations, Balbir Kaur Dhillon

Masters Theses

Over the years, there has been significant interest in defining a hardware abstraction layer to facilitate code reuse in software defined radio (SDR) applications. Designers are looking for a way to enable application software to specify a waveform, configure the platform, and control digital signal processing (DSP) functions in a hardware platform in a way that insulates it from the details of realization.

This thesis presents a tool-based methodolgy for developing and optimizing a Direct Sequence Spread Spectrum (DSSS) transceiver deployed in custom hardware like Field Programmble Gate Arrays (FPGAs). The system model consists of a tranmitter which employs a …

Effect Of Hydrogenon On Mechanical Behavior Of A Zircaloy-4 Alloy, Elena Garlea

Masters Theses

Hydride formation is one of the main degradation mechanisms of zirconium alloys in hydrogen-rich environments. When sufficient hydrogen is present, zirconiumhydride precipitates can be formed. Cracking of the brittle hydrides near a crack tip can initiate the growth of a crack leading to the premature failure of the material. Hydride formation is believed to be enhanced by the presence of residual or applied stresses. Therefore, the increase in the stress field ahead of a crack tip may promote precipitation of additional hydrides. In order to verify these phenomena, the effect of internal stresses on the zirconium-hydride-precipitate formation, and in turn, …