Engineering Commons^™

Meso-Scale Fluidic Devices With Chemical Sensors For Biological Applications, Satya Gowthami Achanta

Doctoral Dissertations

"Molecular oxygen and humidity are some of the major environmental quantities being measured for various industrial and commercial applications. This dissertation focuses on the design, fabrication and characterization of optofluidic biosensor systems for oxygen and humidity quantification using color charge-coupled device (CCD) camera as a photodetector and LED panel as an excitation source. Meso-scale fluidic devices with integrated oxygen and humidity sensors for potential applications to hydrotropic and oxytropic studies of small plant roots have been investigated in this study. Meso-scale sensor platform was fabricated using porphyrine complex as the sensitive dye embedded within Ethyl Cellulose (EC) polymer matrix. Green …

Numerical Simulations Of Fracture Propagation And Sealing: Implications For Wellbore Strengthening, Saeed Salehi

Doctoral Dissertations

"To mitigate the small tolerance between pore pressure and fracture gradients an engineering practice referred to as "wellbore strengthening" is conducted to increase the fracture gradient. The method relies on propping and/or sealing the fractures with specially designed materials. Different competing theories exist for physical wellbore strengthening mechanisms which can be categorized into two groups. The first group explains that strengthening happens as a result of increasing wellbore hoop stress when fractures are sealed while the second group emphasis is on fracture tip isolation with suitable materials and enhancing fracture propagation pressure. The numerical models and lab experiments …

Modeling And Synthesis Of Pvdf-Based Dielectrics For Energy Storage Applications, Xuhui Lu

Doctoral Dissertations

"The purpose of this research was to develop dielectric films for high energy density capacitor applications. Also desired was to develop a deeper understanding of dielectric breakdown and electric energy storage related phenomena through simulation, theoretical analysis, and experimental investigation.

An analytical model incorporating Weibull dielectric strength statistics was developed to establish quantitative relationships between material properties and device performance of self-healing capacitors. The model is useful for designing high voltage capacitors and developing dielectric materials where the effects of electric field-dependent permittivity need to be considered.

In the experimental work, solution-cast poly(vinylidene difluoride) (PVDF) homopolymer PVDF films with high …

The Pricing Of Multiple Exercisable American-Style Real Options, Yu Meng

Doctoral Dissertations

"Real options embedded in a project provide management with the flexibility to alter initial investment decisions, thus making them a practical tool for project planning and budgeting. Additional values are contributed to the underlying project due to the flexibilities that are provided by real options. This dissertation presents two models for pricing multiple exercisable American real options, one that employs the binomial tree method and the other one that employs the finite difference method. Different examples of multiple exercisable real options are discussed to demonstrate the two pricing models. Interactions between options and reality constraints are also considered. These two …

Impact Of Plug-In Hybrid Electric Vehicles On The Power Grid In A Smart Environment, Zahra Darabi

Doctoral Dissertations

This dissertation focuses on the interactions between plug-in hybrid electric vehicles (PHEVs) and the power grid. This study has used the data available through the national household travel survey (NHTS) to obtain realistic information such as the arrival time of vehicles, miles driven, and vehicles types. After data manipulation, the aggregated PHEV charging load profiles (PCLP) have been developed. The results show that the peak of PCLP overlaps with the domestic load peak. In order to alleviate this issue, several charging policies have been developed and their impacts on PCLP have been investigated. As a next contribution, the data obtained …

Analyzing Risk And Catastrophic Accidents: Using Lopa And Human Factors To Improve Safety In Generic Projects, Siddharth B. Damle

Doctoral Dissertations

"Risk assessment and identification in the early stages of any project is critical to the success of that project from time, budget and cost prespective [sic]. Identifying unacceptable risks and making provisions to mitigate those, can reduce the uncertainty in the project and ensure its smooth completion and closure. Various techniques have been developed over time to identify and quantify risks. Inspite of all the available research on risk management tools, accidents continue to happen and projects consistently fail.

The objective of this study is to first, determine the generic risks that can be encountered by a project. A list …

Manufacturing And Characterization Of Soy-Based Polyurethane Composites, Rama Bhadra Raju Vuppalapati

Doctoral Dissertations

"The major cost drivers for composites are raw materials and manufacturing process. Automated manufacturing processes like pultrusion and low cost bio-based raw materials can significantly lower the cost of composites. Polyurethane (PU) resin systems are being introduced in the pultrusion industry as they have higher performance characteristics and manufacturing feasibility when compared to conventional resin systems such as polyester and vinyl ester. PU resin systems are generally characterized as aromatic and aliphatic. Aliphatic PU has lower mechanical properties than the aromatic resin system due to its chemical structure. Nano materials can be used to increase the mechanical properties of aliphatic …

Imaging The Subsurface In Karst Terrain Using Electrical Resistivity Tomography, Evgeniy V. Torgashov

Doctoral Dissertations

"Five electrical resistivity tomography (resistivity) case studies are presented. The first case study, entitled "Springfield Underground", includes ERT data acquired with the purpose of imaging the ceiling of an limestone aggregate mine following simultaneous localized roof failure. The interpretation of the ERT data indicates roof rock failure occurred at the intersection of two previously unmapped near-vertical solution-widened fractures.

At the "Chesterfield Dam" site, resistivity data were acquired to identify the zone of seepage through an earthfill dam. The seepage pathway beneath the dam is interpreted as through a solution-widened fracture, the top of which constituted a segment of the original …

A Socio-Technical Analysis Of Widespread Electric Vehicle Adoption, Onanwa Nneka Egbue

Doctoral Dissertations

A combination of high fuel costs, concerns about petroleum availability, and environmental issues associated with conventional vehicles powered by fossil fuels are driving interests in electric vehicles (EVs). Large-scale deployment of EVs can play a significant role in addressing some of these problems. In spite of the benefits of EVs, several obstacles need to be overcome before EVs will be widely adopted. This research focuses on two socio-technical issues that affect widespread adoption and sustainability of EVs, consumer attitudes and perceptions, and supply chain risks of raw materials for EV battery technology. A major barrier is that consumers tend to …

The Risk Mitigation Strategy Taxonomy And Generated Risk Event Effect Neutralization Method, Daniel A. Krus

Doctoral Dissertations

"In the design of new products and systems, the mitigation of potential failures is very important. The sooner in a product's design mitigation can be performed, the lower the cost and easier to implement those mitigations become. However, currently, most mitigations strategies rely on the expertise of the engineers designing a product, and while models and for failure modes do exist to help, there are no guidelines for performing product changes to reduce risk. To help alleviate this, the risk mitigation strategy taxonomy is created from an empirical collection of mitigation strategies used in industry for failure mitigation, creating a …

Characterization Of Soil Variability For Reliability-Based Design, Sitenikechukwu Onyejekwe

Doctoral Dissertations

"A very carefully planned Missouri-wide field exploration and laboratory investigation program, with a focus on fine-grained soils, was executed with the aim of characterizing the variability of geotechnical parameters statistically with a view to increasing the use of reliability-based design (RBD) among geotechnical engineers. Geotechnical parameters were characterized in terms of both their first and second statistical moments and their coefficient of variation (COV). Their probability distributions and their scale of fluctuation, θ, were also determined. Correlations between difficult-to-obtain parameters and more easily-obtained parameters were developed and the degree of fit of study data to published empirical correlations was investigated. …

Advanced Neural Networks And Their Applications In Smart Grids, Bipul Luitel

Doctoral Dissertations

"Today, neural networks (NN) are used in several system identification and nonlinear control system applications. However, their implementation on large systems has been limited either because of their degraded performance or the amount of time and computation required for implementing them being impractical for real applications. The primary emphasis of this research is on the development of advanced NN - simultaneous recurrent neural networks (SRN) and cellular neural networks (CNN); and methods for learning the complexity of large systems.

US electricity infrastructure is one of the largest and the most critical infrastructure consisting of thousands of generators connected by transmission …

Experimental Investigations Of Pseudospark Discharge And Pseudospark Produced Intense Electron Beams, Jing Hu

Doctoral Dissertations

"This dissertation focuses on the pseudospark discharge, a pulsed discharge discovered for the first time in 1970's. This dissertation is prepared as three journal articles in the style used by Missouri University of Science and Technology. A high voltage pseudospark discharge experiment setup, and discharge and electron beam diagnostic system are constructed and presented in this work. Three journal articles which have been published or are under review are presented in this dissertation on various topics of the pseudospark discharge.

Paper 1 "Experimental investigation of formation time in single-gap pseudospark discharge" is focused on experimental investigations of the time-dependent characteristics …

Real-Time Localization Using Received Signal Strength, Mohammed Rana Basheer

Doctoral Dissertations

"Locating and tracking assets in an indoor environment is a fundamental requirement for several applications which include for instance network enabled manufacturing. However, translating time of flight-based GPS technique for indoor solutions has proven very costly and inaccurate primarily due to the need for high resolution clocks and the non-availability of reliable line of sight condition between the transmitter and receiver. In this dissertation, localization and tracking of wireless devices using radio signal strength (RSS) measurements in an indoor environment is undertaken. This dissertation is presented in the form of five papers.

The first two papers deal with localization and …

A Progressive Collapse Evaluation Of Steel Structures In High Temperature Environment With Optical Fiber Sensors, Ying Huang

Doctoral Dissertations

"In the process of a progressive failure of steel structures in a post-earthquake fire, real-time assessment and prediction of structural behaviors are of paramount significance to an emergency evacuation and rescue effort. However, existing measurement technologies cannot provide the needed critical data such as large strains at high temperature. To bridge this gap, a novel optical fiber sensor network and an adaptive multi-scale finite element model (FEM) are proposed and developed in this study. The sensor network consists of long period fiber gratings (LPFG) sensors and extrinsic Fabry-Perot interferometer (EFPI) sensors or their integration. Each sensor is designed with a …

Design And Experimental Study Of Turbo Equalization For Multiple Antenna Systems, Amirhossein Rafati

Doctoral Dissertations

"Multiple-input multiple-output (MIMO) wireless communication systems have attracted a lot of interest in the past decade due to their capability in delivering high spectral efficiency as well as their robust performance against fading. In MIMO inter-symbol interference (lSI) channels, a severe interference problem occurs due to the lSI and co-channel interference. Thus, the error propagation problem becomes more serious, and its mitigation has to be considered when designing the receiver. In this regard, a turbo equalizer which exchanges soft information between the equalizer and the decoder has been shown to be an effective method to combat the lSI caused by …

Development Of Third Generation Advanced High Strength Steels, Meghan C. Mcgrath

Doctoral Dissertations

"Lightweight duplex steels with combinations of either bainite, acicular ferrite, and austenite or martensite and austenite were investigated as third generation advanced high strength steels targeted for automotive applications. Large additions of manganese (>13 wt%) and carbon (

Duplex steels with different volume fractions of primary δ -ferrite were used to study the crystallography of austenite formed during the peritectic reaction. Solute profiles across the peritectic interface showed aluminum segregated near the interface which promoted bainitic ferrite formation. Thermal treatments were used to manipulate the concentration and type of oxides and the ferrite plate density was found to correlate …

Fractal Oxidation Kinetics And Risk Evaluation Of Spontaneous Combustion In Coal Mines, Yutao Zhang

Doctoral Dissertations

"The spontaneous combustion of coal occurs when air supply is sufficient for the oxidation of coal and air velocity is insufficient for the dissipation of generated heat. Spontaneous combustion, if not eradicated immediately, may lead to coal ignition and even a full-blown fire. The fire may engulf a large area and spread further if they are not immediately attended to. This will not only endanger miners and mining operations, but also result in possible mine closures and even fatalities.

Porous structure has a significant effect on coal adsorption and spontaneous combustion. In this research, fractal theory was utilized to quantitatively …

Friction Stir Welding Of High Temperature Alloys, Jiye Wang

Doctoral Dissertations

"Friction stir welding (FSW) of Ti-6Al-4V alloy, nickel-based and iron-based oxide dispersion strengthened (ODS) alloys (MA754 and MA956) has been studied. The main aspects covered include tool evaluation, microstructural evolution, mechanical properties, and correlation between processing, microstructure and mechanical properties. Tool performance study was carried out for Ti-6Al-4V alloy with refractory tools made of W-1.1%La₂O₃ and two different grades of WC-Co based materials. The results showed that tool degradation can be attributed to mechanical and chemical interaction with processed material. The nature of tool-workpiece interaction was tool material dependent and influenced the resultant microstructure and weld quality in the stirred …

Influence Of Temperature And Microstructural Modification On Formability Of Magnesium Alloys, Arun Mohan

Doctoral Dissertations

"The ß-precipitate free AZ31, ß-precipitate rich AZ91 and a few Mg-Y-Zn alloys were studied to understand the dependence of Mg formability on microstructural condition and temperature. Friction stir processing (FSP) was used to refine the grain size and to obtain desirable distribution of precipitates in the matrix. Since Mg alloys exhibit challenges in achieving room temperature formability, superplastic deformation was utilized. This work focused on high strain rate superplasticity (HSRS, ≥10⁻² s⁻¹) which is more attractive for industrial applications as compared to the slower rates of conventional superplasticity.

Thermally stable fine grains and pinning particles at HSRS temperatures were essential …

Investigation Of Different Approaches To Combine Cable Information And Near-Field Scan Data For Radiated-Field Estimation, Keong W. Kam

Doctoral Dissertations

"Near-field scanning is often used to solve EMC problems. Aside from the purpose of visualization of near-fields, measured near-field data can be used to estimate far-field. One of many challenges associated with using near-field to far-field transform (NFFFT) technique for EMC application is the handling of attached cables. The objective of this investigation is to evaluate different methods to add cable information to the near-field data for far-field estimation. The investigation is carried out using numerical experiments in EMCoS EMC studio, which is a commercial MoM (Method of Moment) tool for EM simulation. Measurement results from a test structure are …

Modeling Carbon Sequestration In Transition Zone To Optimize Storage Potential, Fang Yang

Doctoral Dissertations

"Shallow aquifers are potential candidates for carbon sequestration because of their wide distribution and low injection cost. Injected CO₂ in a shallow region segregates into two zones according to CO₂ phases within the initial reservoir pressure and the maximum bottom hole pressure: gas zone and transition zone. Transition zone is a better option because of favorable CO₂ properties. This work investigated the CO₂ storage potential in transition zone using the compositional simulator CMG-GEM and a design of experiment software iSIGHT. First, it addressed the basic characteristics of CO₂ sequestration in transition zone, and then modeled CO₂ injection with simultaneous water …

Identification And Visualization Of Electromagnetic Coupling Paths & Nonlinear Capacitors For Esd Protection, Hongyu Li

Doctoral Dissertations

"The first topic of this dissertation focuses on developing methods to identify and visualize electromagnetic coupling paths. The basis of the approach is to utilize an analogy between electromagnetic energy flow and fluid flow. This allows one to apply the theories and algorithms of fluid dynamics to electromagnetics and thereby to visualize the electromagnetic energy flow. This in turn can be utilized to identify the electromagnetic coupling path.

The second topic of this dissertation investigates the nonlinearity of capacitors and suggests improved trade-off between electrostatic discharge (ESD) protection and data bandwidth by using the antiferroelectric (AFE) capacitors as ESD protection. …

Two Essays On The Domain Translation From Financial Options To Real Options, Hongyan Chen

Doctoral Dissertations

"Real options (ROs) extend the financial option pricing theory to the valuation of real asset investment and managerial flexibility under uncertainty. However, differences between financial and non-financial markets, and the complex real world environment of applications, build obstacles for the domain translation from financial options to ROs.

This dissertation is motivated by the challenges of domain translation and developed in two essays. The first essay studies the incentive function of ROs (named the RO incentive). The essay develops an option-game framework to model the RO incentive, examines the change of investment behavior caused by the RO incentive, and values the …

Low-Complexity Soft-Decision Feedback Turbo Equalization For Multilevel Modulations, Huang Lou

Doctoral Dissertations

"This dissertation proposes two new decision feedback equalization schemes suitable for multilevel modulation systems employing turbo equalization. One is soft-decision feedback equalization (SDFE) that takes into account the reliability of both soft a priori information and soft decisions of the data symbols. The proposed SDFE exhibits lower signal to noise ratio (SNR) threshold that is required for "water fall" bit error rate (BER) and much faster convergence than the near-optimal exact minimum mean square error linear equalizer (Exact-MMSE-LE) for high-order constellation modulations. The proposed SDFE also offers a low computational complexity compared to the Exact-MMSE-LE. The drawback of the SDFE …

Surface Expressions Of Discontinuities, And The Estimation Of Their 3-D Orientations Using Combined Lidar And Optical Imaging, James Nii Aboh Otoo

Doctoral Dissertations

"The importance of the collection and analysis of data on discontinuities cannot be overemphasized. Problems which include sampling difficulties, risks, limited access to rock faces and exposures, and the delay in data collection has led to a high need for data collection tools and analysis techniques that can overcome these problems.

Discontinuities manifest themselves as either traces or as facets. Traces are linear features that intersect with both the discontinuity and the rock cut. Facets are the actual discontinuity surfaces that are exposed in the rock cut. Facets can be natural or induced. Identifying a facet as either natural or …

Lyapunov Based Optimal Control Of A Class Of Nonlinear Systems, Hassan Zargarzadeh

Doctoral Dissertations

"Optimal control of nonlinear systems is in fact difficult since it requires the solution to the Hamilton-Jacobi-Bellman (HJB) equation which has no closed-form solution. In contrast to offline and/or online iterative schemes for optimal control, this dissertation in the form of five papers focuses on the design of iteration free, online optimal adaptive controllers for nonlinear discrete and continuous-time systems whose dynamics are completely or partially unknown even when the states not measurable. Thus, in Paper I, motivated by homogeneous charge compression ignition (HCCI) engine dynamics, a neural network-based infinite horizon robust optimal controller is introduced for uncertain nonaffine nonlinear …

Investigation Of Wellbore Stability In A North Sea Field Development, Steven Austin Hilgedick

Doctoral Dissertations

"Planning drilling operations is key to the development of oil and natural gas fields. As part of well design, wellbore stability and pore pressure analysis are main factors in determining the safe operating window for selecting mud density. The motivation for this research was to conduct wellbore stability based on exploration wells as basis for planning new offshore field developments with deviated and horizontal wells. A second objective was to investigate the use of a probabilistic approach to wellbore stability, and compare it to the conventional deterministic methods, in order to evaluate the value of including a probabilistic approach to …

Shear And Fracture Behavior Of High-Volume Fly Ash Reinforced Concrete For Sustainable Construction, Carlos Andres Ortega Ordonez

Doctoral Dissertations

"Concrete is the most widely used man-made material on the planet. Unfortunately, producing Portland cement generates carbon dioxide (a greenhouse gas) at roughly a pound for pound ratio. High-volume fly ash (HVFA) concrete- concrete with at least 50% of the cement replaced with fly ash - offers a potential "green" solution. However, because it is still relatively new and has some disadvantages, there are still many questions that need to be answered. Most research to date has consisted only of the evaluation of the strength and durability of HVFA concrete mixtures, while only a limited number of studies have implemented …

The Effect Of Supercritical Water On Crude Glycerin Solution, Jared Bouquet

Doctoral Dissertations

"Crude glycerin solution, a principal byproduct of the conventional biodiesel process, was reacted in supercritical water using a specially designed Haynesʼ Alloy 282 reactor system for the production of hydrogen rich syngas. The effects of temperature, pressure, water-to-carbon molar ratio, reactor residence time, and glycerin-to-methanol weight ratio on the extent of carbon gasification and gas composition were explored. Based on the results, the extent and selectivity of reactions that concurrently occur when methanol and glycerin are in the presence of supercritical water were analyzed. A decomposition reaction pathway for glycerin conversion to syngas was hypothesized, and then utilizing the results …