Engineering Commons^™

Effect Of Decarburization On Microstructure Of Dc-Plasma Nitrided H 13 Tool Steel, P Visuttipitukul, C Paa-Rai, K Hideyuki

Journal of Metals, Materials and Minerals

Decarburization may occur during heat treatment of H13 steel resulting in carbon deficiency near the specimen surface. Microstructures and properties of H13 tool steel after surface treatment such as plasma nitriding can be affected by decarburization. This study is focused on the microstructure of plasma nitrided H13 steel. Decarburized and non-decarburized H13 steel was plasma nitrided for 36-72 ks at temperatures varying from 773 to 823 K. The microstructure of the plasma nitrided layer was analyzed by an optical microscope and Electron Probe Micro Analysis (EPMA). The thickness of the nitriding layer is measured. The microstructures of the decarburized and …

The Influence Of The Strain Rate On The Material Properties Of The Zinc-Coated Sheet, Z Vadasová, M Mihaliková

Journal of Metals, Materials and Minerals

In this paper the influence of the strain rate on the material properties of the zinc-coated sheet of the thickness (1; 1.5; 1.8) mm made from low-alloyed steel ZINKODUR 340 was analyzed. Increasing the strain rate is one of the possible ways to increase cold mechanical work in products. The tensile test is the most useful method for determining the material characteristic such as ductility. This contribution analyzes the influence of loading rate in range from 1 to 1000mm/min on material characteristics of tested steel during the tensile test. Strain rate is one of the most significant factors, which affected …

The Effect Of Long-Term Thermal Exposure At Elevated Temperatures On Microstructures And Mechanical Properties In Centrifugally Casted Iron-Base Alloy, G Lothongkum, N Thaweepornkhasemsukh, P Wangyao

Journal of Metals, Materials and Minerals

This work has an aim to study and investigate the relationship between high temperature exposure conditions on microstructural evolution and mechanical properties in the iron-based alloy, Fe-30.8 Ni - 26.6 Cr alloy, strengthened by carbide precipitation. Two exposure temperatures (900 and 1000°C) with various thermal exposure times are introduced to the as-received alloy. After short-term exposure, it was found that the secondary carbides precipitated early near the primary carbides, which were chromium and niobium/titanium carbide networks. The secondary carbide precipitations were also found in the dendrite cores. The amounts of needle-like carbides and secondary carbide films increased with time and …

Transparent Coating Materials Based On Inorganic/Organic Composites, K Srikulkit, N Rojtinnakorn, R Charoensak

Journal of Metals, Materials and Minerals

A siloxyl group functionalized copolymer of low molecular weight was synthesized, aiming at preparing transparent inorganic/organic coating composites. Two types of coating systems were investigated: two-component system (based on functionalized copolymer-HMMM) a three-component system (based on functionalized copolymer-HMMM-TEOS). Their properties were investigated and compared. Coating films obtained from these systems exhibited good optical clarity, which was largely dependent on the content of indicated Materials. For instance, to prevent phase separation in the 3- component system, TEOS was "effectively" linked to pendent siloxyl groups on the organic moiety Hence, coating formulations containing a high degree of pendent siloxyl groups exhibited better …

Cosign: A Parallel Algorithm For Coordinated Traffic Signal Control, Shih-Fen Cheng, Marina A. Epelman, Robert L. Smith

Research Collection School Of Computing and Information Systems

The problem of finding optimal coordinated signal timing plans for a large number of traffic signals is a challenging problem because of the exponential growth in the number of joint timing plans that need to be explored as the network size grows. In this paper, the game-theoretic paradigm of fictitious play to iteratively search for a coordinated signal timing plan is employed, which improves a system-wide performance criterion for a traffic network. The algorithm is robustly scalable to realistic-size networks modeled with high-fidelity simulations. Results of a case study for the city of Troy, MI, where there are 75 signalized …

Finding A Length-Constrained Maximum-Sum Or Maximum-Density Subtree And Its Application To Logistics, Hoong Chuin Lau, Trung Hieu Ngo, Bao Nguyen Nguyen

Research Collection School Of Computing and Information Systems

We study the problem of finding a length-constrained maximum-density path in a tree with weight and length on each edge. This problem was proposed in [R.R. Lin, W.H. Kuo, K.M. Chao, Finding a length-constrained maximum-density path in a tree, Journal of Combinatorial Optimization 9 (2005) 147–156] and solved in O(nU) time when the edge lengths are positive integers, where n is the number of nodes in the tree and U is the length upper bound of the path. We present an algorithm that runs in O(nlog2n) time for the generalized case when the edge lengths are positive real numbers, which …

Multivariate Discretization Of Continuous Valued Attributes., Ehab Ahmed El Sayed Ahmed 1978-

Electronic Theses and Dissertations

The area of Knowledge discovery and data mining is growing rapidly. Feature Discretization is a crucial issue in Knowledge Discovery in Databases (KDD), or Data Mining because most data sets used in real world applications have features with continuously values. Discretization is performed as a preprocessing step of the data mining to make data mining techniques useful for these data sets. This thesis addresses discretization issue by proposing a multivariate discretization (MVD) algorithm. It begins withal number of common discretization algorithms like Equal width discretization, Equal frequency discretization, Naïve; Entropy based discretization, Chi square discretization, and orthogonal hyper planes. After …

Vision-Based Target Geo-Location Using A Fixed-Wing Miniature Air Vehicle, D. Blake Barber, Joshua D. Redding, Timothy W. Mclain, Randal W. Beard, Clark N. Taylor

Faculty Publications

This paper presents a method for determining the GPS location of a ground-based object when imaged from a fixed-wing miniature air vehicle (MAV). Using the pixel location of the target in an image, with measurements of MAV position and attitude, and camera pose angles, the target is localized in world coordinates. The main contribution of this paper is to present four techniques for reducing the localization error. In particular, we discuss RLS filtering, bias estimation, flight path selection, and wind estimation. The localization method has been implemented and flight tested on BYU’s MAV testbed and experimental results are presented demonstrating …

Ac Conductivity Relaxation Processes In Cacu₃Ti₄O₁₂ Ceramics: Grain Boundary And Domain Boundary Effects, Wei Li, Robert W. Schwartz

Materials Science and Engineering Faculty Research & Creative Works

The ac conductivity of CaCu₃Ti₄O₁₂ ceramics associated with electrical charge carrier motion (ions or vacancies) was investigated as a function of frequency at different temperatures. The long range migration of charge carriers within the ceramic is restricted by two kinds of insulating barriers, namely, grain boundaries and domain boundaries. The potential barriers associated with these boundaries lead to two anomalies in conductivity response and three frequency-dependent contributions to conductivity: long range diffusion of carriers, carrier migration localized within grains, and carrier migration localized within domains.

An Evaluation Of The Ah-64 Night Vision Systems For Use In 21st Century Urban Combat, John Kevin Heinecke

Masters Theses

Currently one of the most arduous and dangerous aviation missions for the military attack helicopter pilot is the night combat mission. The mission entails flight at close proximity to the ground and obstacles such as wires, trees, and buildings in an effort to avoid detection by enemy air defense and insurgent small arms fire. Night flight requires the use of augmented vision systems and enhanced aircraft stability and control systems to allow pilots to effectively see and negotiate those hazards that would otherwise be visible during daylight.

The U.S. Army currently fields two variants of augmented visionics, the Aviator Night …

Determining The Probability Of The Visual Detection Of Sink Marks On Differently Textured Injection Molded Products, Kurt Frederick Hayden

Dissertations

The injection molding segment of the plastics industry has historically exhibited an environment of intense competition. To remain competitive, manufacturers must ensure that molds will produce defect-free parts without multiple design revisions. Designers often use computer simulations to predict design problems before the construction of tooling. These sophisticated software applications will soon have the ability to simulate the final appearance of products. However, the effects of aesthetic defects such as sink marks and splay are often difficult to simulate accurately and effectively.

It is understood that surface textures can conceal minor aesthetic defects. A well-known example is the concealment of …

A Parametric Study Of Water Vapor Condensation In Supersonic Nozzle Flow Fields, Todd Branson Vanpelt

Masters Theses

Combustion driven hypersonic and supersonic wind tunnels are impaired in their flight simulation abilities by the condensation of water vapor introduced into the test stream by the burning byproducts of air and hydrocarbon fuels. The purpose of this study is to evaluate the abilities of a condensation model to predict the beginning axial locations of vapor changing into liquid droplets and study the correlations with initial combustion chamber conditions. A test matrix with different fuels, chamber pressure, and equivalence ratio was applied to the FIRACON model written by Erickson, et al. [7] using the dimensions of the NASA Langley …

A Reconfigurable Supercomputing Library For Accelerated Parallel Lagged-Fibonacci Pseudorandom Number Generation, Yu Bi

Masters Theses

To help promote more widespread adoption of hardware acceleration in parallel scientific computing, we present portable, flexible design components for pseudorandom number generation. Due to the success of the Scalable Parallel Random Number Generators (SPRNG) software library in stochastic computations (e.g., Monte Carlo simulations), we developed an efficient and portable hardware architecture fully compatible with SPRNG’s Parallel Additive Lagged Fibonacci Generator (PALFG). Our general design produces identical results for all the parameter sets that SPRNG supports and yields high performance parallel random number generators which can each generate 162 million 31-bit uniform random integers per second on Xilinx Virtex II …

Fpga Logic Design For Analog-To-Digital-Converter Hardware Utilizing High Speed Serial Data Links, Joshua Brandon Jones

Masters Theses

The Computer Assisted Dynamic Data Monitoring and Analysis System (CADDMAS) used by the aeropropulsion test cells at Arnold Engineering Development Center (AEDC) processes a large amount of high bandwidth accelerometer and strain gage data. Data from each sensor must be digitized before being processed by software running on networked computers. This thesis describes some of the original analog-to- digital converter (ADC) hardware used by the CADDMAS as well as some of its limitations. More up-to-date ADC hardware was designed to be used in the CADDMAS to enhance capabilities required by the aeropropulsion test cells. These new capabilities included an increase …

Integrated Corridor Management: Operational Strategies Under Interstate Diversion Scenarios, Shaun Michael Quayle

Masters Theses

This thesis looks at operational strategies to increase capacity within the context of Integrated Corridor Management (ICM) under a non-recurring Interstate incident scenario. This incident scenario creates lengthy queues and increased delay and travel times on the Interstate, forcing a portion of Interstate traffic to utilize alternate routes throughout the corridor, changing the network traffic patterns. Particular operational strategies are tested under this premise to qualify and mildly quantify the benefits of relaying incident and diversion routing information to corridor drivers, mimicking ITS information dissemination elements such as changeable message signs, highway advisory radio, in vehicle navigation systems and etc. …

Application Of Energy Analysis To The Problem Of Propulsion Driven Nutation Instability Of Spin Stabilized Spacecraft, Tina Morina Rice

Masters Theses

Propulsion driven nutation instability in spin stabilized spacecraft was first observed in the late nineteen seventies. It’s often referred to as the PAM-D coning anomaly, as it first occurred in the McDonnell Douglas Payload Assist Module (PAM-D). Propulsion driven nutation instability is a performance degrading phenomenon that occurs in spin-stabilized spacecraft used for the raising of satellite payloads to geosynchronous orbit. It is characterized by a coning (wobbling) motion that grows to a large degree during the final seconds of motor burn. The instability is clearly related to the increased size of the rocket needed to support the increasing …

Effectiveness Of Alternative Detector Configurations For Option Zone Protection On High-Speed Approaches To Traffic Signals, Jianwen Si

Masters Theses

Safety and efficiency are both prime issues of concern at high-speed signalized intersections. However, although safety problems at high-speed signalized intersections can be mitigated by the application of detector configurations with option zone protection, such configurations can themselves create problems. For example extending the green indication to the maximum time can create max-out situations which terminates the phase without regard for vehicle location. The detector configurations with option zone protection may also produce higher delay times for vehicles on other approaches at the intersection.

In this study, four detector configurations with option zone protection features-- the Single Detector configuration, the …

The Functional Application Of The Propeller Load Curve For Fixed Pitch Propellers, Rebecca Barnett Speas

Masters Theses

This thesis attempts to help the flight test community by using the propeller load curve (also known as prop load) to find brake horsepower (BHP) easily with only a propeller tachometer. This thesis also covers the equation for the propeller load curve.

The flight test was done using a Piper Cherokee 180 equipped with a Lycoming 0-360-A3A engine. The flight test data were collected at University of Tennessee Space Institute (UTSI). This data were then compared to the prop load from the engine manufacturer.

Based on the result of this flight test, using the prop load equation from the Lycoming …

Rheology Of 1- Butyl-3-Methylimidazolium Chloride Cellulose Solutions, Joy Louise Watson

Masters Theses

Cellulose is the most common organic polymer on earth. It is a natural, biodegradable polymer that can be obtained from any number of renewable sources. Wood, a major source of cellulose, contains cellulose, lignin, and hemicelluloses. It can be used to make regenerated cellulosic fibers such as rayon whose manufacturing process involves chemicals which are toxic to humans and the environment. Ionic liquids (ILs) are a class of environmentally benign solvents some of which dissolve cellulose.

Cellulose can be dissolved in 1-butyl-3-methylimidazolium chloride ([C₄mim]Cl), an IL. Solutions of [C₄mim]Cl and cellulose with various concentrations were prepared …

Rebound Ace Tennis Court Surface: The Effect Of Temperature On The Coefficient Of Friction, Denise Helen Bauer

Masters Theses

The study was conducted to determine if temperature affects the safety of Rebound Ace™ surface. The objective of this study is to determine how the COF changes as the Rebound Ace™ tennis court surface temperature increases. The lack of literature on this subject leads to the question of the surface’s safety at higher temperatures. A sample of Rebound Ace™ tennis court surface was tested at eight temperatures related to the climate of Melbourne in January with four different shoes to determine how the COF changes with an increase in temperature.

Temperature and shoe brand were both found to be significant …

Lignin Composites With Phenol-Acrylates Cured By Electron Beam, Seth N. Bowman

Masters Theses

As the major by-product of the pulp and paper industry, determining a use for lignin represents a key priority to almost any bio-materials research organization. The purpose of this study is to investigate the interaction with and effects of lignin within phenol- acrylate composites cured by electron beam, characterizing changes to both physical and chemical properties. In order to more fully characterize the effects of lignin, results of pure lignin as well as cellulose samples subjected to electron beam radiation and tested by FT-IR are presented. For the composite material, results of both DMA and FT-IR spectroscopy will be presented. …

Design And Implementation Of A Complex-Conjugate Shaper And Baseline Restorer For A Silicon-Based Neutron Detector Front-End, Jonathan Lanier Britton

Masters Theses

This thesis presents the design and implementation of a CMOS shaper with baseline restoration for use in the silicon-based neutron detector front-end to be used at the Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory (ORNL). The system consists of a voltage-to-current (V-to-I) converter, a four-pole complex-conjugate semi-Gaussian current-input active filter, and a ground-sensing baseline restorer (BLR) operational transconductance amplifier (OTA). The first prototype chip Patara has been fabricated in the TSMC 0.35-micron process, and experimental results show that proper functionality was achieved. The shaper, which is influenced by a real pole prior to the V-to-I converter, has …

Mathematical Modeling Of High Temperature And High Pressure Dense Membrane For Separation Of Hydrogen From Gasification, Ifeyinwa J. Iwuchukwu

Masters Theses

There is an increasing interest in the use of inorganic membranes as a means of separating gas mixtures at high temperatures and pressures. The most important membrane properties are high permeability and selectivity, and good mechanical, thermal and chemical stability. Dense Pd-based composite membranes are suitable for hydrogen separation and use in catalytic membrane reactors because of their high permeability, good surface properties and high selectivity for hydrogen transport. At UTSI, Pd/AlO23 membranes were prepared by a special method of laser based thermal deposition of the thin film Pd on a ceramic substrate by Nd-YAG laser irradiation of PdCl2 coating …

Design Of A 5-V Compatible Rail-To-Rail Input/Output Operational Amplifier In 3.3-V Soi Cmos For Wide Temperature Range Operation, Robert Lee Greenwell

Masters Theses

This thesis presents the design and implementation of a 5-V compatible operational amplifier in a 3.3-V technology capable of accepting rail-to-rail inputs, providing a rail-to-rail output swing and wide temperature range operation. The major system components consist of a fully-differential input (gain) stage and an output (driver) stage, with protection and bias circuitry components. The op amp is biased by a constant inversion coefficient current reference to optimize its performance over temperature. Measured results demonstrate the functionality of the design, which has been fabricated in a 0.35-µm, partially-depleted silicon-on-insulator (PDSOI) CMOS process.

Outside The Fence,' The Threat To The U.S. Aviation Industry, David Thomas Ramsey

Masters Theses

The purpose of this thesis was to examine the threat to the Aviation Industry from within the United States. The overall investigation starts with one assumption “that there will at some time in the near future be a covert operative group that desires to attack or engage the United States in war on its home land.” The principles of war will be analyzed resulting in covert cell guidance specifically; “economy of force” will require the covert units to be as small as possible to affect as many nodes as possible. Endurance will require the covert team to restrict any tactics …

Characterization Of Processes Used In Nanofabrication Of Digital Electrostatic E-Beam Array Lithography (Deal) Devices, Ryan Benjamine Rucker

Masters Theses

The ultimate goal of this research was to nanofabricate an advanced field emission electron beam lithography platform using an electron beam induced deposition process (EBID) to deposit tungsten (W) nanofibers cathodes. In order to fabricate the devices, it was necessary to characterize the reactive ion etching (RIE) processes for the fabrication of the Digital Electrostatic e-beam Array Lithography (DEAL) device. To optimize the reactive ion etch processes of the silicon and silicon dioxide layers, a JMP desktop statistical discovery software from SAS® was employed to design a set of experiments. The design of experiments (DOE) employed variable conditions of R.F. …

Installing A Night Vision Imaging System In The Cf-188 Hornet: Compatibility Of Warning And Caution Lights, Andrew John Soundy

Masters Theses

The purpose of this thesis was to investigate the NVIS compatibility of fire warning lights as installed during a NVIS upgrade of the CF-188 Hornet for operation with Generation 3 AN/AVS-9 night vision goggles. Data was gathered and compared to the specifications listed in MIL-STD-3009 to determine suitability of the implemented design. Of particular concern during the execution of this project was the compatibility of fire warning lights for operation in both day-time and night-time conditions with respect to NVIS radiance. The initial design placed the NVIS radiance of cockpit warning lights at a level commensurate with that suggested by …

An Experimental Study Of Incompressible Axisymmetric Cavity Flow With Swirl, Lee Charles Wendell

Masters Theses

A systematic study was performed of the flow phenomena in an axisymmetric cavity. Axial flow Reynolds numbers ranged from 100,000 to 530,000 for cavity L/D range of 0.25 to 1.65. Working medium for this study was water reflecting that only incompressible domain of cavity flow was covered in this study. Previous results of axisymmetric flow investigations were reproduced and extended to lower L/D values, with the modified test article. Introduction of swirl in the cavity flow was studied in detail for its effects on the enhancement or suppression of cavity modes that have been measured.

The axial apparatus tested here …

Analysis Of Information Networks Of Freshman Engineering Students, Sara Noel Abdulla

Masters Theses

The main purpose of this study was to determine if social interaction within the University of Tennessee, Knoxville college freshman engineering classrooms correlates with academic performance. Also of interest was whether the interactions between genders had a significant affect on academic performance. Better academic performance is cited in the literature as improving retention and graduation rates; therefore, if factors that affect academic performance can be understood measures can be taken to help students perform better.

Five UT freshman engineering classes were surveyed to determine their level of involvement with the rest of the members in their class. Academic performance of …

Processing And Characterization Of A Novel Bioabsorbable Polymer For Biomedical Applications, Katherine Atchley

Masters Theses

A series of amino acid based bioanalogous polymers have been synthesized by Dr. C. C. Chu at Cornell University for future use in biomedical applications. These poly(ester amide)s have been designed to be bioabsorbable, with particular interest in internal fixation and drug delivery applications. The polymers PEA 4-Phe-4, 4-Phe-Das, and 8-Phe-Das were studied; however, due to better material properties, the focus mainly centered on 4-Phe-4. Since these are new polymers, processing conditions needed to be determined and the structure and properties characterized. The fibers were also processed post-extrusion in an effort to induce orientation and crystallinity within the polymer chains. …