Engineering Commons^™

New Product Launch Decisions Under Competition And Uncertainty: A Real Options And Game-Theoretic Approach To New Product Development, James O. Ostler

Theses and Dissertations

New product development is central to many firms' future success. Not only as a means to continue to maintain their piece of the market, but product development can also be a strategic means for a company to diversify, and/or alter focus to adapt to changing market conditions.

Most of the research in new product development has been on how to do it cheaper and faster than the next guy. However, early commercialization does not guarantee a position of strength in the market. Failures of EMI in CT scanners and Xerox in personal computers illustrate that being first to market does …

A Finite Element Simulation Of Temperature And Material Flow In Fricton Stir Welding, Mark J. Lasley

Theses and Dissertations

The purpose of this research was to use the Transvalor S.A. product, Forge3, to develop a finite element simulation of the friction stir welding process that improves the predictability of temperature evolution and material flow within the plunge portion of the process. Previous modeling created more heating within the billet than experimental results, probably due to the simplification of the simulation with adiabatic boundary conditions. More realistic tooling temperatures were included in this model as these affect heat evolution which is a determining factor in microcrystalline growth. These results were validated by experimental efforts using a billet and tooling instrumented …

A Method For Winding Advanced Composites Of Unconventional Shapes Using Continuous And Aligned Fibers, Abraham K. Allen

Theses and Dissertations

Advanced composites are extremely strong, rigid, and light, even when compared with advanced metals. Advanced composites are replacing high-tech metals as the material of choice for aerospace engineering. However, the processes used to manufacture advanced composites generally lose some of the properties of the materials by their process limitations.

One process that keeps the theoretically awesome qualities of the composite materials in tact is filament winding. Filament wound parts are used as rocket shells, bicycle frame tubes, drive shafts, pressure vessels, etc. Filament winding is an automated process and makes reliable parts to close tolerances. If a straight tube were …

Characterization Of Porous Media And Refractory Materials, Xin Chen

Doctoral Dissertations

Because of its unique advantages on energy savings and casting complex shaper, Lost Foam Casting (LFC) has been widely used as a replacement to the conventional techniques (sand and investment castings). In order to continuously improve the quality of the Lost Foam Casting process for reducing scrap rate and increasing energy savings, the US Department of Energy through its National Industrial Competitiveness through Energy, Environment, and Economics (NICEEE) program sponsored the present study to develop new characterization techniques for enhancing the understanding of the fundamental properties of the refractory materials used in The Lost Foam Casting process. In this study, …

Modeling And Source Apportionment Of Primary And Secondary Pm2.5 In The Atmosphere, Prakash Doraiswamy

Doctoral Dissertations

Source apportionment of PM_2.5 is important to identify the source categories that are responsible for the concentrations observed at a particular receptor. Although receptor models have been used to do source apportionment, they do not fully take into account the chemical reactions (including photochemical reactions) involved in the formation of secondary fine particles. Secondary fine particles are formed from photochemical and other reactions involving precursor gases such as sulfur dioxide (SO₂), oxides of nitrogen (NO_x), ammonia (NH₃) and volatile organic compounds (VOC). The purpose of this research work was to model primary and …

An Alternative Medium For The Measurement Of Soil Suction By The Filter Paper Method, Lori Ann Mcdowell

Masters Theses

Soil suction is the negative pressure within soil particles, which is a function of the moisture content. It plays an important role in agriculture, civil engineering, and geology. Suction is used in practice to identify expansive soils, to locate heave areas, to develop moisture requirements for arid land plants, to measure for collapse of soils around a footing, and to monitor flow movement of moisture. Soil suction varies with moisture content, and the relationship between suction and water content is known as the soil-moisture characteristic curve of a soil. There are several laboratory tests available to measure suction, but the …

Effect Of Micro-Fabric On Consolidation Behavior Of Reconstituted Kaolin Clay, Alexander Page Davis-Smith

Masters Theses

The effect of micro-fabric (i.e. geometric arrangement of platelets) on the one-dimensional consolidation behavior of reconstituted kaolin clay is evaluated using a series of controlled-rate-of-strain (CRS) and incremental load (IL) consolidation tests. The causes and implications of changes in micro-fabric are also explored. Micro-fabric has been altered by adding a dispersing agent to the slurry during specimen preparation; and the changes in micro-fabric have been observed with scanning electron microscope (SEM) images and x-ray diffraction analysis. Properties of the pore fluid are found to affect micro-fabric, even in the presence of significant mechanical stresses. It is observed that the changes …

The Synthesis And Characterization Of Mesoporous Uranium Oxide Catalysts For Oxidative Destructions Of Volatile Organic Compounds And Clean Air Protection, Cyrus Khezr Riahi-Nezhad

Masters Theses

The overall goal of this research was to investigate a new class of mesoporous uranium oxide catalyst used to destroy a range of volatile organic compounds (VOCs), including aromatics and chlorinated organic compounds under conditions which are applicable for U.S. Department of Energy (DOE) facilities and U.S. industries.

Uranium oxides are known to have high efficiency and long-term stability when used to destroy volatile organic compounds (VOCs) when compared with some of the commercial catalysts, such as precious metals, TiO₂, and Co₃O₄ catalysts. Two key factors limiting catalytic activities of uranium oxides prepared by conventional …

The Effectiveness Of Computer-Based Tutorials In Learning Computer-Aided Design Methods For Tool Design Procedures, Andrew Moroni Hall

Theses and Dissertations

Throughout the past twenty-five years the process of designing and manufacturing a product has been revolutionized by the integration of Computer Aided Design (CAD). Although three-dimensional solid modeling, or 3-D CAD offers a better representation of the product in a virtual environment, it can be complicated and difficult to learn. Tutorials have been developed to assist manufacturing tool design student in the learning of 3-D CAD principles as they apply to tool design. This study seeks to test the effectiveness of those tutorials. A BYU tool design class was divided into two groups according to their assigned laboratory time. The …

Improved Signal Integrity In Ieee 1149.1 Boundary Scan Designs, Efren De Jesus Rangel Taboada

Theses and Dissertations

This work is an analysis of solutions to problems derived from inherent timing and signal integrity issues in the use and application of the IEEE 1149.1 Standard at the board level in conjunction with its test system. Setup or hold times violations may occur in a boundary scan chain using IEEE 1149.1 compliant devices. A practical study of the TDI-TDO scan data path has been conducted to show where problems may arise in relationship to a particular board topology and test system. This work points to differences between passing and failing scan path tests for problem characterization. Serial data flow …

The Benefit Of Using Simulation To Improve The Implementation Of Lean Manufacturing Case Study: Quick Changeovers To Allow Level Loading Of The Assembly Line, Jack J. Mcclellan

Theses and Dissertations

In today's competitive manufacturing environment, companies are constantly looking for ways to improve. Because of this, many companies are striving to become "lean" by implementing lean manufacturing, which is a difficult process. To aid in the implementation of lean manufacturing, simulation was used to reduce the trial-and-error period of lean manufacturing and find to optimum approach to implement the lean manufacturing principle. In this research, a case study of implementing level loading of the production schedule for BullFrog International, L.C. will be examined. To make it possible to implement level loading, the thermo-former machine at the beginning of the operations …

A Review Of Setup Practices And Procedures For Creating Ieee 802.11 Wireless Community Networks, Jae M. Theobald

Theses and Dissertations

IEEE 802.11 wireless networking equipment has made it possible to bridge the last mile for new broadband internet service providers. Inexpensive wireless networking equipment and high gain antennas enable high speed internet delivery at a fraction of the cost of installing or upgrading land lines for cable or DSL services. Based on this research, a guide of general practices and procedures is proposed for designing, installing, and maintaining a reliable wireless community area network. Included tests have provided performance results for several types of wireless antennas (including wire grid parabolic dishes, Yagi and Vagi styles, and echo backfire), wireless bridges, …

Modeling Contaminant Transport And Fate And Subsequent Impacts On Ecosystems, Ming Fan

Dissertations

Assessing risks associated with the release of metals into the environment and managing remedial activities requires simulation tools that depict speciation and risk with accurate mechanistic models and well-defined transport parameters. Such tools need to address the following processes: (1) aqueous speciation, (2) distribution mechanisms, (3) transport, and (4) ecological risk. The primary objective of this research is to develop a simulation tool that accounts for these processes. Speciation in the aqueous phase can be assessed with geochemical equilibrium models, such as MINEQL+. Furthermore, metal distribution can be addressed mechanistically. Studies with Pb sorption to amorphous aluminum (HAG), iron (HFO), …

Continuity Of Bridges Composed Of Simple-Span Precast Prestressed Concrete Girders Made Continuous, Libin Yin

Dissertations

Bridges composed of simple-span, precast, prestressed concrete girders made continuous via cast-in-place decks and diaphragms are continuous only for live loads and superimposed dead loads. The continuity diaphragms often crack due to time dependent effects in the girders. These cracks not only impair bridge ascetics and durability, but also reduce "degree of continuity". A related issue is that joint construction is time consuming and expensive due to reinforcement congestion. This dissertation presents a series of field tests, analytical studies, and laboratory experiments concerning the design and performance of this type of bridge.

Based on a survey of the state departments …

Volatile Fatty Acids Effects On Nitrite Removal And Nitrate Formation During Activated Sludge Treatment, Merve Oguz

Doctoral Dissertations

Reaction sequences of nitrifying and denitrifying bacteria are widely used to eliminate nitrogenous compounds from wastewater. During nitrification, ammonia is oxidized to nitrite by autotrophic ammonia oxidizing bacteria and nitrite is further oxidized to nitrate by nitrite oxidizers. Subsequently, nitrate or nitrite is reduced by denitrifying bacteria to gaseous nitrogen compounds. It is common knowledge that nitrification is an aerobic process and denitrification an anaerobic process. However, recent research has shown that denitrification can occur under aerobic conditions in pure cultures. Volatile fatty acids (VFAs), produced during anaerobic treatment processes, can affect both nitrite oxidation and aerobic denitrification. VFAs were …

Travel Characteristics Of Urban Freight Vehicles And Their Effects On Air Quality, Annie Protopapas

Doctoral Dissertations

This research study collected local commercial vehicle data in Knox County, Tennessee from the United States Postal Service and two companies engaged in package pickup and delivery. A second urban commercial vehicle dataset from a wider spectrum of companies in North Carolina was also obtained for comparative analysis. The two datasets are analyzed in a similar manner to develop and compare travel characteristics/parameters commonly used in transportation engineering, such as Daily VMT, Daily Number of Trips, Vehicle Speed, Trip Length, Trip Travel Time and Stop Duration. Statistical tests demonstrate the similarities between certain vehicle classes from the two datasets and …

Verification Of The Correlation Between Peak Particle Velocity (Ppv) And The Response Of A Structure, Sagar Ramesh Kulkarni

Masters Theses

The purpose of this study is to verify the relation between the peak particle velocity (PPV) and the dynamic response of the structure. Based on the study of blast vibrations, the U.S Bureau of Mines correlated the PPV as the reliable parameter for gauging the strength of a blast wave. The prevalent practice of quantifying the ground wave motion is in terms of PPV. The bureau has published the threshold value of PPV=1/2 in/sec as the maximum safe value for a blast wave. This study simulates two structures having two different natural periods resembling the period of short buildings and …

Conformal Refinement Of All-Hexahedral Finite Element Meshes, Nathan Harris

Theses and Dissertations

Mesh adaptation techniques are used to modify complex finite element meshes to reduce analysis time and improve accuracy. Modification of all-hexahedral meshes has proven difficult to the unique connectivity constraints they exhibit. This thesis presents an automated tool for local, conformal refinement of all-hexahedral meshes based on the insertion of multi-directional twist planes into the spatial twist continuum. The contributions of this thesis are (1) the ability to conformally refine all entities of an all-hexahedral element mesh, (2) the simplification of template insertion to multi-directional refinement. The refinement algorithm is divided into single hex sheet operations, where individual refinement steps …

Determining End & Edge Distance Criteria For Tenon Joints In Timber Structures, Sally Summers Nichols

Masters Theses

Traditionally, timber-frame connections use hardwood pegs to hold the main member within the joint. Currently the end and edge distance criteria for these connections have either been established by tradition or by an equivalent steel bolt diameter approximation. The object of this research is to determine a more specific method to establish the end and edge distances for wood pegs in wood connections. This investigation entails two separate tests that were developed from the standard American Society for Testing and Materials (ASTM) testing methods for steel bolds in wood members.

End and edge distance tests were performed on ¾ inch …

Development Of High Performance Concrete For Use On Tennessee Bridge Decks And Overlays, Charles Herbert Hamblin Jr.

Masters Theses

The purpose of this study was to develop a High Performance Concrete mix design to be used on bridge decks and overlays in Tennessee. A total of eight mix designs were tested in this study. Both gap-graded and dense-graded aggregate combinations were used in the study.

Each mix was tested for fresh and hardened concrete properties. Fresh properties include slump, air content, unit weight, and temperature. Hardened properties include 7 and 28-day compressive strength, freeze-thaw durability, drying shrinkage, and chloride ion permeability.

Although further research is recommended, one promising mix was found as a result of this study. Mix 2F1 …

On-Road Mobile Source Emissions In Tennessee For 2002 – An Inventory And Analysis, Jeongran Yun

Masters Theses

Annual on-road mobile source emissions must be updated every three years according to the U.S. Environmental Protection Agency (EPA). The year 2002 is the most recent year to update the emission inventory. The EPA’s computer model, MOBILE6.2, was used to develop the inventory, and the results presented in this report. Emissions of VOC, CO, NO_X, SO₂, NH₃, PM2.5, PM10, and CO₂ were estimated for each of the 95 counties in the state of Tennessee. The latest available traffic data for the year 2002 obtained from the Tennessee Department of Transportation (TDOT) were used …

Microbial Community Changes In Methyl Tert-Butyl Ether (Mtbe)-Contaminated Soils, Bo Yang

Masters Theses

This study addresses two questions regarding the microbial community structure shift in MTBE-contaminated soils: Are known MTBE-degradaers/utilizers present in MTBE-contaminated soils? How is the microbial community affected by the addition of oxygen and the addition of cometabolic substrate?

A new quantitative fingerprinting method, Real-time-t-RFLP, was applied to study the effects of aeration and cosubstrate (toluene) on the microbial community structure of MTBE-contaminated soils. Real-time-t-RFLP, developed from two novel molecular methods (Real-time polymerase chain reaction (PCR) and terminal restriction fragment length polymorphism (t-RFLP)), is capable of quantifying each ribotype in a microbial community. Results of this study showed that microbial community …

Evaluation Of Factors Responsible For High Effluent Suspended Solids Events In The Kuwahee Wastewater Treatment Plant, Patricio Alejandro Moreno

Masters Theses

The potential factors causing high effluent suspended solids (ESS) in Kuwahee Wastewater Treatment Plant (WWTP) are studied in order to properly identify the reason or reasons that might lead to focus future studies in proper remedial actions in the facility. In this document an analysis protocol is established, and several factors are evaluated for potential associations with high ESS events. From the protocol some of the factors were collected from regular operational procedure and others were collected during a study sampling period.

The analysis of those factors included in the protocol showed no biological, or hydraulic, or settling parameters causing …

Air Toxic Emissions Distribution And Performance Analysis Of The Cmaq Air Toxic Model - A Case Study Of Houston Area, Texas, Ramesh Ramachandran Gopal

Masters Theses

Air quality models have been used in the past to predict the ambient air toxic concentration but CMAQ air toxics model, used in this thesis, is the first air quality model, which accounts the toxic chemical reactions in the ambient atmosphere. The main objective of this thesis was to analyze the distribution of air toxics emission in the Houston region, Texas using an emission processing tool and to determine the performance of the advanced air toxics model (CMAQ) used. Each year large amount of air toxics are emitted in the state of Texas, particularly in the Houston region. A study …

Genetic Algorithm-Based Model For Determination Of Efficient Management Strategies For Irrigation Canal Networks, Talaat Taher El Gamel

Civil & Environmental Engineering Theses & Dissertations

An optimization model for the determination of efficient management strategies for an irrigation canal network is developed. The objective is to minimize the total water consumed while satisfying various system constraints. An unsteady flow model is used to simulate the flow in the network. A genetic algorithm- (GA-) based framework is used to solve the model. The suitable GA parameters that should be used within the model, as well as the performance of various constraint-handling techniques, are studied. Uncertainties in crop pattern and water consumption rates are incorporated into the search procedure to identify more reliable solutions. A graphical interface …

Coordinated Regional And City Planning Using A Genetic Algorithm, Michael B. Lowry

Theses and Dissertations

Improved methods of planning are needed to deal with today's issues of traffic congestion, sprawl, and loss of greenspace. Past research and recent legislation call for new methods that will consider a regional perspective. Regional planning is challenged with two difficult questions:

1.Is it possible to achieve regional goals without infringing upon the local autonomy of city planners?

2.Is it possible to objectively analyze the thousands, even millions, of land use and transportation plans to find the best design?

Metropolitan regions across the country have made great efforts to answer the first question. Unfortunately, effective methods for harmonizing the goals …

Performance Of Self-Compacting Concrete, Mohamed Samir Rushdy

Archived Theses and Dissertations

Concrete compaction is one of the indispensable fundamentals of concrete manufacturing. However, thorough compaction cannot always be insured. This can be wholly or partially encountered in congested sections, out-of reach deep foundations and narrow or irregular precast components. On the other hand, typical vibrators were considered as contributor to health hazards to workers. Self-compacting concrete (SCC) is an emerging concrete where the cohesive yet flowable consistency of the concrete itself secures adequate placement with high level of homogeneity and little or no segregation. Such concrete is primarily achieved by incorporating admixtures that is referred to as viscosity modifying (VM) admixtures …

Development Of Dynamic Recursive Models For Freeway Travel Time Predictions, Xiaobo Liu

Dissertations

Traffic congestion has been a major problem in metropolitan areas, which is caused by either insufficient roadway capacity or unforesceable incidents. In order to promote the efficiency of the existing roadway networks and mitigate the impact of traffic congestion, the development of a sound prediction model for travel times is desirable.

A comprehensive literature review about existing prediction models was conducted by investigating the advantages, disadvantages, and limitations of each model. Based on the features and properties of previous models, the base models including exponential smoothing model (ESM), moving average model (MAM), and Kalman filtering model (KFM) are developed to …

Three-Dimensional Mechanical Behavior Of Kaolin Clay With Controlled Microfabric Using True Triaxial Testing, Amit Prashant

Doctoral Dissertations

Clays in their natural state are mostly anisotropic because of their modes of deposition. Many boundary value problems in geotechnical engineering involve soil elements that are subjected to stress paths with varying relative magnitudes and orientation of principal stresses. In clay, these soil elements may also have different orientations of its microfabric. It is a well-known fact that the variation in relative magnitudes and orientation of principal stresses and the microfabric of clay have significant effect on the stress-strain, pore pressure and shear strength behavior of clay. In order to study this behavior of clay from a normally consolidated to …

Dynamic Left-Turn Phase Optimization Using Fuzzy Logic Control, Zhenyang Li

Doctoral Dissertations

The left-turn movement at an intersection has long been a concern of traffic engineers as it is a major capacity reduction factor. Different left-turn signal phasings have been shown to result in significant differences in delay, intersection capacity, and even safety level.

First, past studies about leading and lagging signal phases and signal control application are overviewed. Then this research gives a theoretical analysis of signal left-turn phase operations at both isolated and coordinated signalized intersections, compares the difference in delay based on leading and lagging left-turn signal phase designs, analyzes the influences of traffic control delay components for leading …