Digital Commons Network^™

Friction Stir Form Welding Of Aluminum Structures, Kamini Ashokkumar Gupta

Masters Theses

"The objective of this work was to demonstrate the applicability of friction stir welding (FSW) technology in the automotive industry. Increasing fuel prices, stringent safety and emission norms are continuously striving automakers to make lightweight, fuel efficient vehicles. Automotive engineers are researching for alternate materials in order to meet weight savings targets. Use of aluminum in place of steel in a car has been increasing for making lightweight vehicles. Conventional welding and spot welding are used as preferred joining methods by the automotive industry. However, if aluminum is used in place of steel alternate joining methods are to be researched. …

Laboratory Analysis Of Small Strain Moduli In Compacted Silts, David M. Weidinger

Masters Theses

"Soil compaction quality control accounts for a significant portion of geotechnical practice. Often the performance of a roadway can be directly linked to the quality of the compacted subgrade. A poor subgrade can result in weak areas in the road causing excessive deflections at the surface, ultimately leading to a pot hole or uneven surface and an unpleasant ride for the travelers. Vehicles passing over a section of highway causes small strains in the founding soil. These strains accumulate over time. A better understanding of how the compacted soil responds at small strains could shed light on improving the quality …

Wireless Mote-Based In-Process Diagnostics Using Hand-Held Tools In Network Enabled Manufacturing Environments, Reghu Anguswamy

Masters Theses

"When complex manufacturing systems are considered, post process inspection can be a very time consuming and costly. In addition, no inspection data is typically collected unless a major problem is encountered. Real-time monitoring of the manufacturing processes and verification of its product quality are two important factors to reduce the manufacturing lead time and to ensure safety and quality.

In this thesis, a diagnostics and root-cause analysis scheme with a single channel wireless routing protocol for real-time monitoring of process quality of pull-type fastening operations is first presented. The overall architecture has been implemented on a Huck45 pull-type tool, which …

Polymer Reinforced Aerogels And Composites A. Polyimide Crosslinked Aerogels B. Silica-Polymethylmethacrylate Composites, Vishal U. Patil

Masters Theses

"Crosslinking of aerogels is a promising approach to combine the advantages of inorganic and polymeric materials. In the present study, two types of polyimide-silica hybrid aerogels, APTES-BTDA-MDA (mol ratio: 2:2:1) and APTES-BTDA-MDA (mol ratio: 2:3:2), were synthesized using a sol-gel process followed by heating in order to imidize the polyamic acid that is formed quickly and is covalently bonded to silica. The hybrid aerogels were made using 3-aminopropyltriethoxysilane (APTES) endcapped polyamic acids and tetramethoxysilane (TMOS) as precursors. Polyimide crosslinked aerogels were characterized by TGA, SEM, FT-IR, BET, solid state NMR and gas pycnometry. These hybrid aerogels exhibit high thermal stability …

Development Of A Gis-Based Seismic Hazard Screening Tool, Andrew J. Wilding

Masters Theses

"Geotechnical earthquake engineering hazards have consequences that are difficult to mitigate, especially for infrastructure systems with multiple and distributed components. In the last few decades significant progress has been made to provide more accurate and useful methods to evaluate hazards for complex systems. One of these advances involves the application of spatial analysis and geographic information systems (GIS), for not only presenting data as maps, but also providing more practical and usable solutions, such as calculating the hazard potential with spatial distribution. This thesis studies the evaluation of geotechnical earthquake engineering hazards within a GIS environment, using borehole-specific data and …

Design For Manufacturing For Friction Stir Welding, Harish Bagaitkar

Masters Theses

"This thesis is divided in two parts. In the first part, technical feasibility of implementing Friction Stir Welding (FSW) for automobile chassis fabrication is discussed using a case study. In the case study, Design for Manufacturing (DFM) principles are applied to manufacture an aluminum automobile chassis. Various DFM issues such as Tool Accessibility Issue, Joint Configuration Issue, and Fixture Support Issue along with relevant guidelines such as component geometry change and component elimination are discussed in the first section. Results show that more than 50% of the chassis joints can be welded using FSW technique. The second part of the …

Dynamic Equations With Piecewise Continuous Argument, Christian Keller

Masters Theses

"We extend the theory of differential equations with piecewise continuous argument to general time scales. Linear and quasi-linear systems of functional dynamic equations with alternating retarding and advanced argument will be investigated and conditions for globally asymptotic stability of those systems will be stated and proven. Furthermore, oscillation criteria for linear first-order equations with piecewise continuous argument will be established"--Abstract, page iii.

Thermal Characterization And Vibration Of Solder Alloys, Brandon Lee Brinkmeyer

Masters Theses

"Recent legislation and growing environmental concerns have forced the electronics industry to discontinue the use of tin-lead (SnPb) solder. Although the legislation did not directly affect aerospace and defense industries, future transitions to lead-free (LF) solders are inevitable. Differences exist between these high reliability systems and consumer electronics, first of which is a very small production rate and a long life cycle which often leads to repair or rework procedures which introduce the potential for mixing of SnPb and LF solder. In this study, Sn-3Ag-0.5Cu (SAC305) was mixed with Sn-37Pb solder in amounts of 0, 25, 50, 75, and 100 …

Adaptive Modulation For Cognitive Radios, Gaurav Sharma

Masters Theses

"This thesis examines the benefits of using adaptive modulation in terms of spectral efficiency and probability of bit error for cognitive radio networks. In channels that fluctuate dynamically over time, systems that are based upon the conventional methods of fixed modulation formats do not perform well. Adaptive modulation provides many parameters that can be adjusted relative to the channel fading, including data rate, transmit power, instantaneous BER, symbol rate, and channel code rate or scheme. In this thesis, a systematic study on the increase in spectral efficiency obtained by optimally varying combinations of the modulation formats for a cognitive radio …

Behavior Of Full-Scale Rc T-Beams Strengthened In Shear With Externally Bonded Frp Sheets, Antonio Brancaccio

Masters Theses

"Shear deficiencies in many bridges may be considered even more critical than flexural deficiencies since shear failures occur without advance warning and are more catastrophic. Deficiencies in shear can be due to insufficient shear reinforcement, use of outdated design codes, a reduction in the steel area due to corrosion, or an increase in the service load due to change of occupancy for the structure.

In recent years, many research studies have investigated the shear behavior of reinforced concrete (RC) beams strengthened with fiber-reinforced polymer (FRP) composites, however, most of them were conducted on small-scale specimens. Thus, analytical models and design …

Via Transition Modeling And Charge Replenishment Of The Power Delivery Network In Multilayer Pcbs, Matteo Cocchini

Masters Theses

"In the first article of this thesis, the charge delivery in the power distribution network for printed circuit board has been analyzed in the time-domain. Performing all the simulations and analyzing the PDN physics and modeling, I contributed to a better understanding of the time-domain decoupling mechanism. The second paper studies the noise coupling sing a segmentation approach combined with a via-to-antipad capacitance model and a plane-pair cavity model. Building equivalent circuit models as well as analyzing design strategies, I contributed to a new approach for the PDN analysis in multilayer PCBs. The third article discusses how to estimate the …

Modeling And Measurement Of Thermal Residual Stresses And Isotope Effects On Thermo Physical Properties Of Zrb₂-Sic Ceramics, Michael P. Teague

Masters Theses

"Commercially available finite element modeling software (ABAQUS) was used to investigate the internal residual stresses that develop as a result of cooling from processing temperatures in ZrB₂-SiC ceramics. The size and shape of the SiC particles were varied to evaluate their effect on the residual stresses. Results were compared to experimental data and showed similar trends, where increasing SiC particle size increased tensile stress and also decreased strength. Models were used to analyze benefits of novel shaped SiC inclusions and also better understand the short comings of the composites. An attempt to validate the models using neutron diffraction to measure …

Textural Analysis Of A Rhyolite Dike Of The Southern Oklahoma Aulacogen At Medicine Park, Oklahoma, Sean Patrick O'Donnell

Masters Theses

"Detailed analysis of the modal abundance and crystal size distribution (CSD) of glomerocrystic quartz and alkali feldspar phenocrysts in a porphyritic "rhyolite" dike at Medicine Park, Oklahoma were integrated with known phase relationships in the system SiO₂-NaAlSi₃O₈-KAlSi₃-O₈-H₂O to constrain the history of this intrusion"--Abstract, page iv.

Forecasting Using The T-Method, Parthiv Akshay Shah

Masters Theses

"The T-method is a technique developed by Genichi Taguchi to calculate an overall prediction based on the signal-to-noise ratio without the use of Gram-Schmidt orthogonalization. The Taguchi Methods, also known as robust design principles, is used to determine the optimal levels of control factors through planning and conducting experiments, and evaluating their results. The primary goal of Robust Design is to minimize variance in the presence of noise factors to achieve a robust process. T-Method is one of the techniques evolved from Taguchi Methods. This thesis illustrates the use of the T-method and outlines it steps using four forecasting case …

A Rapid Method For Determination Of Alpha Hydroxy Acids In Seawater And Biological Fluids At Trace Levels, Ryan Lee Schwiderski

Masters Theses

"Alpha hydroxy acids (AHAs) - carboxylic acids with a hydroxyl substitution on the alpha carbon are an important class of molecules. Hydroxy Methyl Thiobutanoic Acid (HMTBA) is an α-hydroxy analog of essential amino acid methionine; it finds extensive use as a feed supplement for avian and bovine species. Efficacy of alpha hydroxy acid uptake is important for nutritional studies and such studies rely on accurate and precise methods for determination of these chemicals in biological samples. Several methods for AHAs determination have been reported, however, the methods are tedious, requiring multiple sample preparation steps. Experiments reported in this thesis were …

Lateral Reservoir Compartmentalization Of The Woodford Shale In The Arkoma Basin, Southeastern Oklahoma, Adedapo Omotunde Ajibade

Masters Theses

"Analysis of geochemistry, mineralogy, total organic content (TOC) and rock evaluation pyrolysis on Woodford Shale well cuttings taken from a horizontal well (Quaid 13-30H) drilled in the Arkoma Basin (Pittsburg County), Oklahoma shows no significant variation in the thermal maturity, type, and/or quantity of organic matter. This is interpreted to mean that the organic matter of the Woodford Shale is relatively homogeneous and has all undergone similar thermal history. In addition, the analysis shows that there are lateral variations in the gas geochemistry in which the shale appears to be broken up into sections, some of which are more enhanced …

An Approach For Human Swarm Interaction, Shishir Bashyal

Masters Theses

"This study shows that appropriate human interaction can benefit a swarm of robots to reach to goal more efficiently. The common belief in swarm robotics that user intervention adversely affects intelligence of the swarm is studied carefully to show that the traditional human-robot interaction approaches are not suitable for human swarm interaction. A set of desirable features for human swarm interaction is identified and an interaction architecture is proposed that has all of the desirable features. A swarm simulation environment is then created that allows simulating a swarm behavior in an indoor environment. Three different applications of the swarm are …

Synthesis Of Nanostructured Conducting Polymers And Their Application As Gas Sensors, Zhe-Fei Li

Masters Theses

"A single-step, bottom-up technique based on a nanostructured conducting polymer has been used to fabricate sensors. Small amounts of aqueous solutions of aniline, a dopant, and an oxidant were placed on an interdigitated electrode array. Ultraviolet (UV)-irradiation of the solutions enhanced polymerization, yielding a highly porous film of polyaniline nanofibers with mean diameters of around 100 nm and lengths on the order of 1 µm. Solutions that were not irradiated formed bulk-like polyaniline films. Nanofibers and bulk polyaniline sensors were exposed to vapors in an argon carrier gas including: chloroform, a weak proton donor; toluene, a vapor that causes polymer …

Manufacturing Of Transparent Composites Using Vacuum Infusion Process, Jason Niles Gallagher

Masters Theses

"Glass is the most commonly used transparent material. However, glass is not suitable where low weight and high strength are required. For many applications there exists a need for mechanically strong composite materials of high optical quality and transparency equivalent to window glass. Glass fiber reinforced transparent composite is a viable solution. Transparency is maintained by precisely matching the refractive index of the matrix with that of the glass fiber. Aircraft canopies and transparent armor can be potential applications for this new class of materials.

In the present work, transparent composites are manufactured using vacuum infusion process. Both rectangular glass …

Block Level Link Path Design And Multilayer Via Transition Model Assembly Using S-Parameters, Francesco De Paulis

Masters Theses

"In high-speed data communication systems the complexity of link path between transmitters and receivers present a challenge for designers to maintain an acceptable bit error rate. An approach is presented in this thesis to design the link path on a block-by-block basis. The unique advantage of this approach lies on the physics-based model of each block, which then relates performance to geometry and makes design improvement and optimization possible. A tool based on the manipulation of frequency domain data has been designed to help in the design and analysis process of fast communication systems. It accepts as inputs the frequency …

A Laboratory Study Of Struvite Precipitation For Phosphorus Removal From Concentrated Animal Feeding Operation Wastewater, Sushmita Dhakal

Masters Theses

"Struvite precipitation occurs spontaneously in many wastewater treatment facilities as a nuisance. However, struvite precipitation is now being studied as a method to concurrently treat high phosphorus wastewaters and generate a valuable product. Many factors influence the precipitation of struvite such as component -ion molar ratios, pH, aeration, solubility, solids and mixing energy. In the present work, struvite precipitation in the actual swine wastewater was studied by strategically controlling aeration, pH, and mixing"--Abstract, page iv.

The Carbonatite-Hosted Apatite Deposit Of Jacupiranga, Se Brazil: Styles Of Mineralization, Ore Characterization And Association With Mineral Processing, Paula Regina Alves

Masters Theses

"The carbonatite-hosted apatite deposit of Jacupiranga is located in southeastern Brazil. The major styles of apatite mineralization are veins or veinlets, small pods or patches, disseminated apatite, and massive aggregates (locally). The concentration of apatite involves grinding of the carbonatite, removal of magnetite with a magnet drum, size classification with cyclones, and flotation to suppress carbonates and collect apatite. Samples of carbonatite were collected from more recent exposures of the mine and drill holes. This study utilized a variety of microscopy methods, namely transmitted and reflected light, cathodoluminescence (CL), and scanning electron microscopy (with wavelength-dispersive spectrometers for mineral compositions)"--Abstract, page …

A Separation Criterion And Non-Intrusive Thickness Measurement Technique For Shear-Driven Films, Mark A. Friedrich

Masters Theses

"The behavior of a shear-driven thin liquid film at a sharp expanding corner is of interest in many engineering applications. However, details of the interaction between inertial, surface tension, and gravitational forces at the corner that result in partial or complete separation of the film from the surface are not clear. The focus of this study was to develop a criterion to predict the onset of shear-driven film separation from the surface at an expanding corner as well as to develop a film thickness measurement technique that could be used to obtain an average film thickness for input into the …

Application Of Product Family Design For Engineered Systems In Changing Market Space, Mohit Goswami

Masters Theses

"The focus of this paper is on the design of an engineered system for a changing market space. Due to the dynamic nature of the customer requirements, the specification of product offerings in a particular market may change. Manufacturers need to strategically design their product portfolio in such a way that their profitability is maximized, while deploying the right number of platforms necessary for deriving product variants. Depending on the system architecture, subsystems can be classified into one of the two types: scalar subsystems and modular subsystems. Each subsystem is defined by various parameters, performance criteria, and physical compatibility constraints. …

Derivation Of New Double-Input Dc-Dc Converters Using The Building Block Methodology, Karteek Gummi

Masters Theses

"In most power electronic systems, the instantaneous input and output power vary by time and are not exactly identical with each other. Hence, providing a good match between them is a complicated task to deal with if not impossible. Furthermore, due to the wide variation range of the processed power, the overall efficiency of the system is not high. The solution is to hybridize the system using an energy storage unit like in hybrid electric vehicles, power factor correction systems, and photovoltaic systems. Multi-input converters play a key role in such hybridized systems, where it is required to have more …

Defect-Tolerance And Testing For Configurable Nano-Crossbars, Mandar V. Joshi

Masters Theses

"Moore's Law speculated a trend in computation technology in terms of number of transistors per unit area that would double roughly every two years. Even after 40 years of this prediction, current technologies have been following it successfully. There are however, certain physical limitations of current CMOS that would result in fundamental obstructions to continuation of Moore's Law. Although there is a debate amongst experts on how much time it would take for this to happen, it is certain that some entirely new paradigms for semiconductor electronics would be needed to replace CMOS and to delay the end of Moore's …

Indication Of Cylinder Pressure Rise Rate By Means Of Vibration And Acoustic Emissions Of An Internal Combustion Engine, Jeffery A. Massey

Masters Theses

"The focus of this study is to investigate the ability of the vibration and acoustic emissions of an internal combustion engine to indicate the cylinder pressure rise rate (PRR). Investigations are conducted on both a small-single cylinder spark-ignition (SI) engine and a larger multi-cylinder compression-ignition (CI) engine. Vibration measurements were made on both engines, however only acoustic measurements were made on the SI engine. Specific vibration and acoustic frequency bands were identified as correlating to energy generated from combustion and energy generated by cylinder cavity resonances"--Abstract, page iii.

Hazards Assessment Of St. Charles County - Earthquakes And Floods, Amy Lynn Krauch

Masters Theses

"Located on the northernmost limits of the St. Louis metropolitan area, St. Charles County has been, and continues to be, one of the fastest-growing counties in the country. The county consists of several major cities featuring extensive industry, retail, and agriculture. Bounded by the Missouri River on the south and the Mississippi River on the north and east, St. Charles County is predominantly flat, low-lying terrain at great risk to periodic flooding. The county is also well within the area of influence for several local seismic zones, increasing the susceptibility to earthquake damage. Given the apparent risk to both flood …

Fabrication Of Soy Oil Epoxy Resin Based Composites, Vinay Prabhakar Pai

Masters Theses

"A renewable resource derived epoxidized ester - Epoxidized Allyl Soyate (EAS) yields a versatile epoxy resin system that can be used in pure form combination with bis-phenol epoxy systems to obtain high strength composite materials. EAS containing composites materials exhibit higher toughness and impact resistance than the traditional bis-phenol epoxy composites. These resin systems were found to be compatible with different fibers and screens such as glass fibers, glass mats, carbon fibers and metallic wire screens including those obtained from an automobile tire recycling process. The materials were tested for mechanical properties including tensile and flexure strengths. The highest tensile …

Performance Of Fire-Damaged Prestressed Concrete Bridges, Wendy Leann Moore

Masters Theses

"The purpose of this experimental program was to develop and analyze the effects of fire damage on prestressed concrete bridges. Flexural strength and serviceability of the bridge were measured by inputting fire damaged data into a parametric study spreadsheet consisting of a typical 3-span continuous prestressed concrete bridge. Data was obtained by exposing two types of specimens to different levels of elevated temperatures and then cooling them at room temperature to simulate fire damage. The two specimen types were prestressing strands which were tested in tension and concrete blocks with a single prestressing strand embedded in the center, which were …