Digital Commons Network^™

Stress Measurement And Development Of Zirconium Diboride-Silicon Carbide Ceramics, Jeremy Lee Watts

Doctoral Dissertations

"Research presented in this dissertation focused on the production of ZrB₂-SiC composites and their characterization; in particular their mechanical properties and thermally generated residual stresses. Thermally generated stresses were measured using Raman spectroscopy as well as both neutron and x-ray diffraction. For 70 vol% ZrB₂ - 30 vol% SiC composites neutron diffraction revealed that the SiC phase was under ~880 MPa compressive stress and the ZrB₂ phase was under ~450 MPa tension at room temperature. It was also discovered that stresses began to accumulate at ~1400 ⁰C upon cooling from the processing temperature (1900 ⁰C -2000 ⁰C). Raman spectroscopy and …

Ceeme: Compensating Events Based Execution Monitoring Enforcement For Cyber-Physical Systems, Thoshitha T. Gamage

Doctoral Dissertations

"Fundamentally, inherently observable events in Cyber-Physical Systems with tight coupling between cyber and physical components can result in a confidentiality violation. By observing how the physical elements react to cyber commands, adversaries can identify critical links in the system and force the cyber control algorithm to make erroneous decisions. Thus, there is a propensity for a breach in confidentiality leading to further attacks on availability or integrity. Due to the highly integrated nature of Cyber-Physical Systems, it is also extremely difficult to map the system semantics into a security framework under existing security models. The far-reaching objective of this research …

Effect Of Hydrophobicity And Surface Roughness On Two-Phase Flow In Rectangular Microchannels, Gautham C. Unni

Doctoral Dissertations

"Two-phase flows in microchannels have received significant attention recently, and have become the cornerstone of numerous microfluidic devices. Microscale devices used for bioengineering applications, oil recovery, and chemical and catalytic microreactor applications involve the transport of bubbles in confined fluidic networks in channels of micrometer length scale. These types of two-phase flows result in pressure variations, leading to an overall increase in pressure drop. Among various flow parameters, pressure drop is extensively used in design of microfluidic devices. There are several parameters that affect the pressure drop across two-phase flow in microchannels. In the present study, the goal is to …

Epitaxial Electrodeposition Of Metal Oxide Films And Superlattices Which Exhibit Resistance Switching, Rakesh V. Gudavarthy

Doctoral Dissertations

"This dissertation presents an investigation of the electrodeposition of metal oxide films and superlattices on conducting polycrystalline and single crystal substrates. In the first part of the study, electrodeposition of magnetite (Fe₃O₄) films and superlattices in the magnetite/zinc ferrite system which exhibit resistance switching is studied. Paper I reports the electrodeposition of superlattices in the magnetite/zinc ferrite system and shows that only superlattices exhibit multistate resistance switching. In paper II, simple polycrystalline magnetite films electrodeposited on stainless steel crystals exhibit multistate resistance switching which can be tuned by controlling the composition of the films. Paper II describes the epitaxial electrodeposition …

Cross-Layer Design For Network Performance Optimization In Wireless Networks, Xuan Gong

Doctoral Dissertations

"In this dissertation, I use mathematical optimization approach to solve the complex network problems. Paper l and paper 2 first show that ignoring the bandwidth constraint can lead to infeasible routing solutions. A sufficient condition on link bandwidth is proposed that makes a routing solution feasible, and then a mathematical optimization model based on this sufficient condition is provided. Simulation results show that joint optimization models can provide more feasible routing solutions and provide significant improvement on throughput and lifetime. In paper 3 and paper 4, an interference model is proposed and a transmission scheduling scheme is presented to minimize …

Exploratory Study Of Barriers To Use Of Feigenbaum's Quality Cost Strategy Within Design Engineering Firms, David Patrick Loduca

Doctoral Dissertations

"It has been more than a half century since Armand Feigenbaum first conceived of the strategy for the manufacturing sector, yet quality costing strategies have not found a foothold among engineering firms. This study was aimed at constructing a set of theories that explains possible barriers to acceptance of the Feigenbaum strategy by analyzing attitudes and opinions of players in an actual engineering firm and the culture in which they work.

Modeled after the Feigenbaum approach and tailored to the business model of engineering and architectural firms, a system was developed to classify and record costs of quality. A local …

Influence Of Particle Size And Specimen Preparation On The Iowa Pore Index, Christopher Paul Davis

Masters Theses

"This study was performed in order to identify a size correction that would allow aggregate of different sizes, other than the standard 1/2-3/4-inch fraction, to be used in the Iowa Pore Index (IPI) test. This size correction would allow for the IPI to be determined for aggregate gradations of material that have a nominal maximum size (NMS) smaller than 3/4-inch. The interest in a size correction for the IPI developed from its use in a Durability Factor (DF) estimation equation. The estimation equation was developed with the use of 19 different DF from Missouri aggregate sources, where eight aggregates had …

Production And Characterization Of Supported Palladium Nanoparticles On Multiwalled Carbon Nanotubes By Gamma Irradiation, Jessika Viviana Rojas Marin

Masters Theses

"Carbon nanotubes are being studied for a variety of applications due to their outstanding mechanical, chemical, electrical, and optical properties that make them interesting in different areas. Nowadays, different methods to modify the structure of the nanotubes are being developed in order to expand the application fields of such materials. In this work, palladium nanoparticles were directly produced and supported on multi-walled carbon nanotubes (MWCNT) by gamma irradiation. A solution with a 2:1 water-isopropanol ratio was prepared and mixed with palladium chloride as precursor of palladium ions. Radiolysis of water produces certain species that reduce the ions down to a …

Categorization And Experimental Evaluation Of Anchorage Systems For Fiber-Reinforced Polymer Laminates Bonded To Reinforced Concrete Structures, Stephen V. Grelle

Masters Theses

"While externally-bonded fiber-reinforced polymer (FRP) composites are commonly used for the strengthening of structurally deficient reinforced concrete (RC) members, the topic of anchoring FRP to concrete to achieve higher design strengths has not been addressed. Many innovative systems have been developed to anchor FRP to concrete, but the research involving these anchorage systems is not centralized and is therefore difficult to access. Additionally, systematic testing procedures for evaluating the strength of an anchorage system have not been widely used. To aid in the organization of anchorage system research and facilitate a better understanding of anchorage system behavior, a categorization system …

Design Of A Current Probe For Measuring Ball-Grid-Array Packaged Devices, Tianqi Li

Masters Theses

"A current probe to measure BGA ball currents via magnetic induction has been designed. The probe is manufactured on a 4 layer flex circuit and has been validated by full wave simulations and measurements. The feature size of the probe is very tiny that it almost pushes the limit of flex-circuit technology. Several critical manufacturing problems were happened, and they have been solved now. The probe allows measuring currents of a 1 mm pitch BGA ball directly. Its operating frequency stretched from tens of MHz up to 3GHz. The BGA probe's mutual inductance is approximately 11 pH, and with amplifiers …

Evaluation Of Skin-Core Adhesion Bond And Low-Velocity Impact Behavior Of Honeycomb Sandwich Structures, Ramanjaneya R. Butukuri

Masters Theses

"Composite sandwich structures offer several advantages over conventional structural materials such as lightweight, high bending and torsional stiffness, superior thermal insulation and excellent acoustic damping. Some of the failure mechanisms in a composite sandwich structure are de-bonding of the composite facesheets from the core structure and damage due to low-velocity impact. In the first part of this work, adhesive fillet formation and adhesive mechanical strength are evaluated as a function of several different sandwich construction design variables. The effect of film adhesive thickness is studied. A process for reticulation of the adhesive is applied and studied. Optimized combinations of core …

Development Of Lower Cost Imaging Systems For Laser Metal Deposition Process, Shyam Barua

Masters Theses

"Laser Metal Deposition (LMD) has been used as an additive manufacturing process in industries such as aerospace and die castings. LMD is especially useful in repair applications involving die repair. However, it is still not used widely in industry due to variations in the quality of parts. There are multiple interactions between various factors which influence the quality of deposit.

There exists a need for defect detection systems to detect any changes in the deposition quality during deposition. On demand detection enables adjustment in process parameters and minimization of rework cost.

Vision systems have been used extensively in the industry …

A Neural Network Based Approach For Path Planning On Costmap, Songjie Chen

Masters Theses

"In this thesis, a path planning method using a three-level hierarchical system model is proposed. In the top level of the hierarchy, the given location points to visit are taken as waypoints. The waypoint navigation process is formulated as a traveling salesman problem (TSP). The Lin-Kernighan algorithm is used to solve the TSP and transfer the solution to the lower level of the hierarchy. In the middle level, the path is represented by a grid-based costmap. A novel modified Grossberg neural network is designed to solve the point-to-point path planning. The bottom level of the hierarchy smoothens the path with …

Life Expectancy Evaluation And Replacement Schedule Development For Led Traffic Indicators, Casey Robert Noll

Masters Theses

"LED (light-emitting diode) technology is being widely adopted for use in sustainable traffic signal management. However, the useful life and luminosity characteristics have not been sufficiently studied in the field to provide departments of transportation with cost-effective replacement strategies based on the realities for LED indicators. LED indicators fail when their luminous intensity (LI) falls below a pre-specified threshold, posing a danger to traffic. This research details a field study of LED indicators in Missouri and develops a replacement schedule based on key findings. Rates of degradation and subsequently the useful life of each type of LED indicator were calculated …

Creating A Sustainable Transportation Workforce: Identifying Skills, Abilities And Knowledge For Future Transportation Workforce, Sandhya Gopalakrishnan

Masters Theses

"The recruitment and retention of a transportation workforce capable of adapting to the requirements of emerging sustainable technologies is an important concern for engineering managers in transportation. Although there is an increasing demand for transportation professionals to fill positions stemming from retirement or created by innovations in sustainable transportation systems, the supply is decreasing. The objective of this research was to fill the gap between the supply and demand of skilled workforce by presenting a life-cycle framework for recruiting and retaining the transportation workforce as part of succession planning efforts funded by the U.S. Department of Transportation's Transportation Education Development …

Assess Commercialization Feasibility Of Algae-Based Bio-Fuel With Dashboard And Scorecard Technologies, Madhur Chopra

Masters Theses

"The growing energy depleting energy supplies and increasing environmental pollution has motivated researchers across the globe to look for alternative energy sources. Various energy sources have been identified but none of them have the capability of realistically replacing the fossil fuels and meeting the current demand. Algae based bio-fuels give some hope but producing them at large scale is a challenge which needs to be overcome.

The underlying objective of this research project is two folds. Firstly, the project aims to assist with the commercialization of algae based bio-fuels by developing Dashboard based and Balanced Scorecard based monitoring prototypes. The …

Development Of A Graphical User Interface For The Study Of Parallel-Connected Solar Arrays, Nisha Nagarajan

Masters Theses

"For any solar array it is necessary to be able to harness the maximum possible power from it. A new technology is proposed to improve the efficiency of solar arrays and harness maximum potential power as well by connecting the solar panels in parallel. This thesis describes the development of a graphical user interface for the evaluation of this parallel-connected solar array technology and to compare different scenarios for solar arrays to predict the potential power output to decide the best configuration for an application. This is done via several computations and analysis of field data. The first paper describes …

Thermomechanics Of Curves In Space, Pavan Krishna Kanchi

Masters Theses

"Several biological molecules are known to form helices and coiled structures, such as DNA, collagen, bacterial flagella, and proteins. The backbones of such molecules may be modeled as a curve in three dimensions. A variational problem for the functional of the total free energy required to perturb moving curves in space is considered. The total energy of a curve in three dimensions is minimized y with a general intensive energy, which is a function of position, and the invariants, curvature and torsion. Three types of moduli are identified: stretching, bending and torsional moduli. As a result, three independent force balances …

Synthesis And Toxicity Studies Of Imidazolium-Based Ionic Liquids, Ninu Madria

Masters Theses

"There is a considerable recent interest in the applications of room temperature ionic liquids (RTILs) as green solvents in organic synthesis and as nonvolatile electrolytes in lithium ion batteries. A variety of commercially available imidazolium based RTILs have been used for these applications, mainly due to their negligible vapor pressures, high thermal stabilities, wide liquid range, wide electrochemical windows and high anodic stability. The state of the art lithium ion batteries require the use of electrolytes that have relatively low viscosities at temperatures as low as -35°C. This thesis describes the synthesis of novel oxygenated and fluorinated imidazolium based RTILs …

Novel Transparent Conductive Materials: Understanding And Prediction, Yaou Song

Masters Theses

"Transparent conductive oxides (TCOs) such as doped In₂O₃, ZnO, SnO₂ or CdO are highly attractive due to their special properties, which are electrical conductivity and optical transparency. The lack of complete understanding of the fundamentals behind this unique phenomena and rapidly increasing commercial demand draw a lot of interest in investigating this kind of materials. More efficient, environmentally friendly and less expensive transparent conductive materials are needed for a variety of applications, and a general understanding of the origins of the unusual behavior would help further search for potential transparent conductive (TC) candidates. Understanding the basic properties of conventional TCOs …

Crustal Structure And Evolution Beneath The Colorado Plateau And The Southern Basin And Range Province, Lamuail Bashir

Doctoral Dissertations

"Stacking of about 15,500 P-to-S receiver functions recorded at 72 USArray and other broadband seismic stations placed on the Colorado Plateau and the SBRP in Arizona revealed systematic spatial variations in crustal Vp/Vs, crustal thickness and amplitude of P-to-S converted phases. Our results reveal that the BRP is characterized by a thin crust (28.2 ± 0.5 km), a mean Vp/Vs of 1.761 ± 0.014 and a mean amplitude (R) of P - to - S converted wave (relative to that of the direct P wave) of 0.181 ± 0.014 that are similar to a typical continental crust, consistent with the …

Impact Of Channel Statistics And Correlation On Underwater Acoustic Communication Systems, Jesse Scott Cross

Masters Theses

"Several statistical properties of underwater acoustic channels gathered from experiment data are analyzed. The baseband channel impulse response (CIR) is estimated using a time domain least squares technique with a sliding window applied to the probing sequences. From the CIR estimation, the probability distribution functions (PDFs) of the magnitude, real part, imaginary part, and phase of the CIR are calculated. Gamma, Rayleigh, and compound k distributions are fitted to the magnitude PDF and the fitness of the distributions are calculated with a two-sample Kolmogorov-Smirnov test. Other statistics such as the autocorrelation function, coherence time, and scattering function are evaluated. The …

Quantifying The Carbon Footprint Of Lean Waste, Kristen Donovan Balinski

Masters Theses

"The objective of this paper is to provide a method of quantifying lean wastes in terms of carbon dioxide emissions by using value stream mapping. Lean manufacturing, a process based on waste identification and reduction, is a growing trend in industry and a proven method of lowering costs. The environmental impact of these wastes can be quantified by identifying the metrics associated with them, and using existing reports to convert those metrics into measurements of carbon dioxide. Growing environmental concerns are prompting federal government regulation of greenhouse gas or carbon dioxide emissions, as seen in the American Clean Energy and …

Integration Of Model-Based Systems Engineering And Virtual Engineering Tools For Detailed Design, Akshay Kande

Masters Theses

"Design and development of a system can be viewed as a process of transferring and transforming data using a set of tools that form the system's development environment. Conversion of the systems engineering data into useful information is one of the prime objectives of the tools used in the process. With complex systems, the objective is further augmented with a need to represent the information in an accessible and comprehensible manner. The importance of representation is easily understood in light of the fact that the stakeholder's ability to make prompt and appropriate decisions is directly related to his understanding of …

Multiple-Input Multiple-Output System Simulation For Spinning Vehicles, Samuel James Petersen

Masters Theses

"This paper investigates the performance of a multiple-input multiple-output (MIMO) wireless communication system, when the transmitter is located on a spinning vehicle. In particular, a 2x2 MIMO system is used, with Alamouti coding at the transmitter. Both Rayleigh and Rician statistical models are considered in this paper and are combined with a deterministic spinning model to simulate the channel. The spinning of the transmitting vehicle, relative to the stationary receive antennas causes additional signal fading, and complicates the decoding and channel estimation. The simulated bit error rate is the primary performance metric used. A 4x2 asymmetric Alamouti coding scheme is …

Analysis And Modeling Of Depth-Of-Cut During End Milling Of Deposited Material, Haythem Gaja

Masters Theses

"This study addresses depth-of-cut detection and tool-workpiece engagement using an acoustic emission monitoring system during milling machining for a deposited material. Online detection of depth-of-cut presents many technical difficulties. Researchers have used various types of sensors and methods to assess the depth-of-cut and surface errors. Due to the strong correlation between acoustic emission and cutting depth during the depth end milling process, it is useful to forecast the depth-of-cut from the acoustic emission signal. This work used regression analysis to model and detect the depth-of-cut. The experiments were carried out on a Fadal vertical 5-Axis computer numerical control machine using …

Adaptive Rule-Based Malware Detection Employing Learning Classifier Systems, Jonathan Joseph Blount

Masters Theses

"Efficient and accurate malware detection is increasingly becoming a necessity for society to operate. Existing malware detection systems have excellent performance in identifying known malware for which signatures are available, but poor performance in anomaly detection for zero day exploits for which signatures have not yet been made available or targeted attacks against a specific entity. The primary goal of this thesis is to provide evidence for the potential of learning classier systems to improve the accuracy of malware detection.

A customized system based on a state-of-the-art learning classier system is presented for adaptive rule-based malware detection, which combines a …

Numerical Simulation Of Relative Permeability Modifier Effect On Oil And Water Production, Murad Mohammedahmed Abdulfarraj

Masters Theses

"Excess water production is one of the most prevalent operational problems that oil companies are facing. Polymers and polymer gels have been used widely to control excess water production for mature oilfields. It is well known that polymers/gels can reduce the permeability to water (Krw) much more than that to oil (Kro). This phenomenon is called disproportionate permeability reduction (DPR) and the polymers or gels that exhibit this behavior are called relative permeability modifier (RPM). When RPMs are placed in reservoir, reduced permeability to water can lead to decreased water production, and sometimes increased hydrocarbon production, therefore prolonging the useful …

The Origin Of Quartz Glomerocrysts: Insights From The Rhyolite Dike At Medicine Park, Ok, Sedeg Ahmed E. Ahmed

Masters Theses

"The origin of quartz glomerocrysts a distinctive petrographic feature of the rhyolite dike in Medicine Park, Oklahoma, was investigated using transmitted light and cathodoluminescence microscopy to determine if quartz glomerocrysts formed during quartz crystallization or during quartz dissolution. Quartz glomerocrysts are typically comprised of two to six individual phenocrysts of quartz and commonly exhibit subhedral partially embayed crystal forms with very rare euhedral phenocrysts in both glomerocrysts and individual quartz phenocrysts. The size range of the individual quartz phenocrysts are 0.08mm to 1.7mm while the size range is 0.08mm to 3.25mm for quartz glomerocrysts . Cathodoluminescence revealed that individual quartz …

Evaluating The Effectiveness Of Multi-Spectral Remote Sensing Data For Lithological Mapping In Arid Regions: A Quantitative Approach With Examples From The Makkah Neoproterozoic Region, Saudi Arabia, Nawwaf Awad Al Muntshry

Masters Theses

"This work quantitatively evaluates the effectiveness of multi-spectral remote sensing data for geological mapping in arid regions. For this, Landsat Thematic Mapper (TM) data covering part of the Neoproterozoic Arabian Shield around the Makkah region in Saudi Arabia are used. The Makkah region is dominated by a variety of layered and intrusive rocks covered by unconsolidated sediments. The Landsat TM data have six spectral bands in the visible and near infrared (VNIR) and shortwave infrared (SWIR) with thirty meters spatial resolution.

The Optimum Index Factor (OIF) has been computed to determine the best Red-Green-Blue (RGB) band combination emerging from the …