Engineering Commons^™

Development Of A Nitrogen Incorporated Ultrananocrystalline Diamond Film Based Field Emitter Array For A Flat Panel X-Ray Source, Chrystian Mauricio Posada

Doctoral Dissertations

"As an alternative to conventional X-ray sources, a flat panel transmission X-ray source is being developed. A field emitter array (FEA) prototype to be incorporated as cold cathode in this flat panel X-ray source was fabricated for this work. Using the Particle-in-Cell code OOPIC Pro, an initial FEA was designed through simulations. Based on the simulation results, a FEA prototype was fabricated using conventional microfabrication techniques. Planar nitrogen-incorporated ultrananocrystalline diamond (N-UNCD) films were used as field emitters. This N-UNCD based FEA prototype was composed of 9 pixels distributed in a 3x3 array, with a pixel size of 225x225 µm, and …

Electric-Drive Vehicle Emulation Using Advanced Test Bench, Poria Fajri

Doctoral Dissertations

"Vehicle electrification is considered to be the most promising approach toward addressing the concerns on climate change, sustainability, and rapid depletion of fossil fuel resources. As a result electric-drive vehicle (EDV) technology is becoming the subject of many research studies, from academia and research laboratories to automotive industries and their suppliers. However, a crucial step toward the success of EDV implementation is developing test platforms that closely emulate the behavior of these vehicles.

In this dissertation, a new approach for emulating an EDV system on a motor/dynamometer test bench is investigated. Two different methods of emulation are discussed which are …

Development Of A Flat-Panel X-Ray Source, Edwin Joseph Grant

Doctoral Dissertations

"A novel flat-panel transmission type X-ray source was developed for both medical and industrial use. Depending on the geometry of the given situation, the flat-panel X-ray source could be used in tomography, radiography or tomosynthesis. Furthermore, the unit could be used as a portable X-ray scanner or an integral part of an existing detection system. The design incorporates a field emission cathode made of ultra-nanocrystalline diamonds (UNCD) doped with nitrogen. These field emitters show good electron output at low power and can be deposited over large areas as is the case with carbon nanotube "forest" (CNT) cathodes. This work presents …

Semantic Model And Updated Screening Criteria For Polymer Flooding, Laila Dao Saleh

Doctoral Dissertations

"Enhanced oil recovery (EOR) processes produce oil that conventional methods leave behind, where interfacial forces, heavy oil viscosity, and reservoir heterogeneity make it difficult to produce. Many EOR methods are available but usually cannot be used at the same time for a candidate reservoir. Therefore, it is important to select the most appropriate EOR process from among the possible techniques. EOR screening criteria have been created using EOR datasets and serve as the first step to compare the suitability of each technique for a specific reservoir. Most of these datasets are based on field data collected from EOR surveys published …

Automated Classification Of Malignant Melanoma Based On Detection Of Atypical Pigment Network In Dermoscopy Images Of Skin Lesions, Nabin K. Mishra

Doctoral Dissertations

“Melanoma causes more deaths than any other form of skin cancer. Early melanoma detection is important to prevent progression to a more deadly stage. Automated computer-based identification of melanoma from dermoscopic images of skin lesions is the most efficient method in early diagnosis. An automated melanoma identification system must include multiple steps, involving lesion segmentation, feature extraction, feature combination and classification. In this research, a classifier-based approach for automatically selecting a lesion border mask for segmentation of dermoscopic skin lesion images is presented. A logistic regression based model selects a single lesion border mask from multiple border masks generated by …

Degradable Nanocomposite Preformed Particle Gel For Chemical Enhanced Oil Recovery Applications, Paul Tongwa

Doctoral Dissertations

”This work presents two new materials that can be potentially used in conformance control to increase ultimate oil recovery from mature oilfields.

The first product is a degradable nanocomposite preformed particle gel for enhanced in-depth mobility control. Three different types of degradable nanocomposite preformed particle gels were synthesized. These three nanocomposite hydrogels were made using Laponite XLG, Calcium Montmorillonite, and Sodium Montmorillonite nanomaterials. It was observed that after degradation, Laponite XLG nanocomposite hydrogels had the highest post-degradation viscosity (4437 cp), followed by sodium nanocomposite hydrogels (129 cp), and lastly calcium nanocomposite hydrogels (75.5 cp). Thus, degradable Laponite XLG nanocomposite hydrogels …

Cerium-Based Conversion Coatings On Magnesium Alloys, Carlos E. Castaño

Doctoral Dissertations

"This research is primarily focused on gaining a better understanding of the deposition and corrosion behavior of cerium-based conversion coatings (CeCCs) on AZ31B and AZ91D Mg alloys. Deposition of homogenous and protective CeCCs was highly dependent on the surface preparation steps. The best results were obtained when Mg samples underwent grinding, acid cleaning, and alkaline cleaning processes. This reduced the number of active cathodic sites and promoted the formation of a protective Al-rich Mg oxide/hydroxide layer. Electrochemical properties of the CeCCs were also strongly correlated with morphological, microstructural, and chemical characteristics. Protective CeCCs were deposited on both AZ31 and AZ91 …

Elevated Temperature Mechanical Properties Of Zirconium Diboride Based Ceramics, Eric W. Neuman

Doctoral Dissertations

"Research presented in this dissertation focused on the mechanical behavior of ZrB₂ based ceramic at elevated temperatures. Flexure strength, fracture toughness, and elastic modulus were measured at temperatures up to 2300ºC for three compositions: monolithic ZrB₂ (Z); ZrB₂ - 30 vol% SiC - 2 vol% B₄ C (ZS); and ZrB₂ - 10 vol% ZrC (ZC). In argon, Z, ZS, and ZC had strengths of 210 (at 2300ºC), 260 (at 2200ºC), and 295 MPa (at 2300ºC), the highest temperatures tested for each composition. Fractography was used extensively to characterize the strength limiting flaws as a function of temperature. Strength of ZS …

Experimental And Computational Investigation Of Flow Of Pebbles In A Pebble Bed Nuclear Reactor, Vaibhav B. Khane

Doctoral Dissertations

"The Pebble Bed Reactor (PBR) is a 4th generation nuclear reactor which is conceptually similar to moving bed reactors used in the chemical and petrochemical industries. In a PBR core, nuclear fuel in the form of pebbles moves slowly under the influence of gravity. Due to the dynamic nature of the core, a thorough understanding about slow and dense granular flow of pebbles is required from both a reactor safety and performance evaluation point of view.

In this dissertation, a new integrated experimental and computational study of granular flow in a PBR has been performed. Continuous pebble re-circulation experimental set-up, …

Hardware Implementation Of Multiple-Input Multiple-Output Transceiver For Wireless Communication, Bing Han

Doctoral Dissertations

"This dissertation proposes an efficient hardware implementation scheme for iterative multi-input multi-output orthogonal frequency-division multiplexing (MIMO-OFDM) transceiver. The transmitter incorporates linear precoder designed with instantaneous channel state information (CSI). The receiver implements MMSE-IC (minimum mean square error interference cancelation) detector, channel estimator, low-density parity-check (LDPC) decoder and other supporting modules. The proposed implementation uses QR decomposition (QRD) of complex-valued matrices with four co-ordinate rotation digital computer (CORDIC) cores and back substitution to achieve the best tradeoff between resource and throughput. The MIMO system is used in field test and the results indicate that the instantaneous CSI varies very fast in …

Hardware Integration Of Ultracapacitor Based Energy Storage To Provide Grid Support And To Improve Power Quality Of The Distribution Grid, Deepak Somayajula

Doctoral Dissertations

"Grid integration of distributed energy resources (DERs) is increasing rapidly. Integration of various types of energy storage technologies like batteries, ultracapacitors (UCAPs), superconducting magnets and flywheels to support intermittent DERs, such as solar and wind, in order to improve their reliability is becoming necessary. Of all the energy storage technologies UCAPs have low energy density, high power density and fast charge/discharge characteristics. They also have more charge/discharge cycles and higher terminal voltage per module when compared to batteries. All these characteristics make UCAPs ideal choice for providing support to events on the distribution grid which require high power for short …

A Unified Bond Theory, Probabilistic Meso-Scale Modeling, And Experimental Validation Of Deformed Steel Rebar In Normal Strength Concrete, Chenglin Wu

Doctoral Dissertations

"Bond between deformed rebar and concrete is affected by rebar deformation pattern, concrete properties, concrete confinement, and rebar-concrete interfacial properties. Two distinct groups of bond models were traditionally developed based on the dominant effects of concrete splitting and near-interface shear-off failures. Their accuracy highly depended upon the test data sets selected in analysis and calibration. In this study, a unified bond model is proposed and developed based on an analogy to the indentation problem around the rib front of deformed rebar. This mechanics-based model can take into account the combined effect of concrete splitting and interface shear-off failures, resulting in …

Performance Evaluation Of Polyurethane Composites Using Vacuum Infusion Process, Mohaned M. Mohamed

Doctoral Dissertations

"Glass fiber-reinforced polymer composites have promising applications in infrastructures due to their low cost, high specific stiffness/strength, and corrosion resistance. The pultrusion process is often used to manufacture glass fiber-reinforced polyurethane (PU) composite. The objective of this study is to use thermoset PU resin to manufacture high quality composites for infrastructure applications using vacuum assisted resin transfer molding (VARTM) process. Using VARTM to fabricate PU resins presents unique challenges. Several modifications however have helped with overcoming these problems. In part I of the research, the mechanical performance of two different PU resin not only evaluated but also compared to one …

An Integrated Plasma Spectroscopic And Capacitive Sensing Platform For Water Quality Diagnostics, John William Sweeney

Doctoral Dissertations

Even in modern times, the consumption of polluted water continues to inflict tremendous suffering on millions of people worldwide that is largely preventable with adequate sanitation practices, routine water quality diagnostics, and treatment. However, conventional water quality monitoring practices remain a time consuming endeavor, where water samples collected on-site are transported to off-site laboratories for evaluation with laboratory-scale chemical analysis devices. While considerable efforts have been made to miniaturize these devices for in-field use, many of the devices reported in the literature provide an incomplete assessment of a water contaminant's environmental impact by focusing on identifying its chemical composition and …

Halloysite Nanotube Composites For Sustained Release Of Antimocrobial Agents (Antiseptics And Antibiotics), Wenbo Wei

Doctoral Dissertations

Encapsulation of antimicrobial agents (simple antiseptics and more specific antibiotics) within micro-scale and nano-scale containers may provide prolonged and more evenly distributed drug release. One of such containers proposed at Louisiana Tech is natural halloysite clay nanotubes. Halloysite is an aluminosilicate tube with a length of approximately 1 µm, outer diameter of approximately 50 nm, and internal lumen of 15 nm. The chemical composition of halloysite is similar to more common clay–kaolinite, and it can be described as rolled sheets of kaolinite. Halloysite, loaded with drugs inside its lumen, has shown aqueous release of the loaded chemicals over 10-20 hours …

Micro Solar Thermal Energy Development And Use For Mems Power Applications, Emmanuel Ogbonnaya

Doctoral Dissertations

Increasing focus on alternative energy sources has produced significant progress across a wide variety of research areas. One particular area of interest has been solar energy. The sun represents sustainable and renewable energy source capable of meeting present energy needs without compromising the ability of future generations to meet theirs. Energy from the sun can be utilized in multiple ways. Direct rise in modern power generation typically involves either photovoltaic systems or large-scale solar thermal energy installations. While large-scale solar thermal energy generation is well advanced, there has been comparatively little research on smaller scale thermal energy collection and application. …

Modeling And Control Of Nanoparticle Bloodstream Concentration For Cancer Therapies, Scarlett S. Bracey

Doctoral Dissertations

Currently, the most commonly used treatments for cancerous tumors (chemotherapy, radiation, etc.) have almost no method of monitoring the administration of the treatment for adverse effects in real time. Without any real time feedback or control, treatment becomes a "guess and check" method with no way of predicting the effects of the drugs based on the actual bioavailability to the patient's body. One particular drug may be effective for one patient, yet provide no benefit to another. Doctors and scientists do not routinely attempt to quantifiably explain this discrepancy. In this work, mathematical modeling and analysis techniques are joined together …

Multi-Segment Multi-Criteria Approach For Selection Of Trenchless Construction Methods, Ashikul Islam

Doctoral Dissertations

The research work presented in this thesis has two broad objectives as well as five individual goals. The first objective is to search and determine the minimum cost and corresponding goodness-of-fit by using a different combination of methods that are capable of resolving the problem that exists in multiple segments. This approach can account for variations in unit price and the cost of the design and the inspection associated with multiple methods. The second objective is to calculate the minimum risk for the preferred solution set. The five individual goals are 1) reduction in total cost, 2) application of Genetic …

Position-Adaptive Localization Of An Electro-Magnetic Source Using Static And Mobile Wireless Sensor Networks, Miguel D. Gates

Doctoral Dissertations

We present new results in detection and localization of a hidden emitter using Wireless Sensor Networks (WSNs). While this type of problem has been explored extensively, this research combines multiple dynamics, such as mobility and adaptation, to extend the value beyond the typical search mission. Using Micro-Aerial Vehicles (MAVs), in conjunction with multiple static wireless sensor nodes, we create a hybrid sensor network capable of detection and localization of a hidden electro-magnetic (EM) emitter.

In order to localize the emitter, a Received Signal Strength Indicator (RSSI) is used as an approximation of distance from the transmitter to the revolving receivers. …

A Computational Model Of Nanoparticle Transport And Delivery In Tumor Tissue, Vishwa Priya Podduturi

Doctoral Dissertations

Determining the factors that influence the delivery of nanoparticles to tumors and understanding the relative importance of each of these factors is fundamental to optimize the drug delivery process. In this research, a model that combines random walk with the pressure driven flow of nanoparticles in a tumor vasculature is modeled. Nanoparticle movement in a cylindrical tube with dimensions similar to the tumor's blood capillary with a single pore is simulated. Nanoparticle velocities are calculated as a pressure driven flow over imposed to Brownian motion. During the study, the effect of red blood cells (RBC) is also studied by comparing …

Multiscale Modeling Of Enzyme-Catalyzed Methanol Production By Particulate Methane Monooxygenase, Katherine K. Bearden

Doctoral Dissertations

In this work, the conversion of methane to methanol by the particulate Methane Monooxygenase (pMMO) enzyme is investigated using a multi-scale modeling approach. This enzyme participates in carbon cycling and aids in the removal of harmful atmospheric methane, converting it to methanol. The interaction between pMMO and a neighboring enzyme that is present in the same organism is studied, and the unknown pMMO active site is elucidated and tested for methane oxidation towards the production of methanol.

Fundamental knowledge of pMMO's mechanism is not fully understood. Understanding how this enzyme works in nature will provide information towards designing efficient synthetic …

Low Soluble Drug Encapsulation Based On Architecture Of Layer-By-Layer Assembly For Longer Circulation Time And Targeted Therapy, Pravin Pattekari

Doctoral Dissertations

A combined effect of sonication and layer-by-layer assembly (LbL) enhances the solubility of many poorly soluble inorganic and organic materials by forming stable particles with ca. 200 nm size and up to 90 wt% of loading. The entire method is reproducible, easy-to-handle, and flexible for varying surface properties according to the application of the materials. The method develops good colloidal stability of materials in buffers and maintains architecture for future improvement. A top-down approach, with a combined effect of sonication and LbL assembly, ruptures the material and allows adsorption of oppositely charged polyelectrolytes simultaneously. Thus, the approach is applicable for …

The Effect Of Network Transitions On Spontaneous Activity And Sycnhrony In Devloping Neural Networks, Jude P. J. Savarraj

Doctoral Dissertations

Connectivity patterns of developing neural circuits and the effects of its dynamics on network behavior, particularly the emergence of spontaneous activity and synchrony, are not clear. We attempt to quantify anatomical connectivity patterns of rat cortical cultures during different stages of development. By culturing the networks on dishes embedded with micro electrode arrays, we simultaneously record electrical activity from multiple regions of the developing network and monitor its electrical behavior, particularly its tendency to fire spontaneously and to synchronize under certain conditions. We investigate possible correlations between changes in the network connectivity patterns and spontaneous electrical activity and synchrony. Cocultures …

Intrinsic Mode Function Synchronization Measures For The Anticipation Of Seizures In Epilpsy, Daniel William Moller

Doctoral Dissertations

Epileptic seizures affect as many as 50 million people and often occur without warning or apparent provocation. We explore the applicability of noise-assisted Ensemble Empirical Mode Decomposition (EEMD) for patient-specific seizure anticipation synchronization measures as applied to the EEMD intrinsic mode function (IMF) output. Intracranial EEG data were obtained from pre-surgical monitoring at the Epilepsy Center of the University Hospital of Freiburg. Data from twenty patients were analyzed. For each recorded channel, non-overlapping time windows were submitted to the EEMD algorithm, producing twelve levels of IMFs. IMF synchronization measures (mean and maximum coherence, mean and maximum cross-correlation, correlation coefficient and …

Unmanned Ground Vehicle Navigation And Coverage Hole Patching In Wireless Sensor Networks, Guyu Zhang

Doctoral Dissertations

This dissertation presents a study of an Unmanned Ground Vehicle (UGV) navigation and coverage hole patching in coordinate-free and localization-free Wireless Sensor Networks (WSNs). Navigation and coverage maintenance are related problems since coverage hole patching requires effective navigation in the sensor network environment. A coordinate-free and localization-free WSN that is deployed in an ad-hoc fashion and does not assume the availability of GPS information is considered. The system considered is decentralized and can be self-organized in an event-driven manner where no central controller or global map is required.

A single-UGV, single-destination navigation problem is addressed first. The UGV is equipped …

Nonlinear Granger Causality And Its Application In Decoding Of Human Reaching Intentions, Mengting Liu

Doctoral Dissertations

Multi-electrode recording is a key technology that allows the brain mechanisms of decision making, cognition, and their breakdown in diseases to be studied from a network perspective. As the hypotheses concerning the role of neural interactions in cognitive paradigms become increasingly more elaborate, the ability to evaluate the direction of neural interactions in neural networks holds the key to distinguishing their functional significance.

Granger Causality (GC) is used to detect the directional influence of signals between multiple locations. To extract the nonlinear directional flow, GC was completed through a nonlinear predictive approach using radial basis functions (RBF). Furthermore, to obtain …

Multi-Scale Characterization Of Nanostructured Sodium Aluminum Hydride, Shathabish Narasegowda

Doctoral Dissertations

Complex metal hydrides are the most promising candidate materials for onboard hydrogen storage. The practicality of this class of materials is counter-poised on three critical attributes: reversible hydrogen storage capacity, high hydrogen uptake/release kinetics, and favorable hydrogen uptake/release thermodynamics. While a majority of modern metallic hydrides that are being considered are those that meet the criteria of high theoretical storage capacity, the challenges lie in addressing poor kinetics, thermodynamics, and reversibility. One emerging strategy to resolve these issues is via nanostructuring or nano-confinement of complex hydrides. By down-sizing and scaffolding them to retain their nano-dimensions, these materials are expected to …

Synthetic Aperture Radar-Based Techniques And Reconfigurable Antenna Design For Microwave Imaging Of Layered Structures, Mojtaba Fallahpour

Doctoral Dissertations

"In the past several decades, a number of microwave imaging techniques have been developed for detecting embedded objects (targets) in a homogeneous media. New applications such as nondestructive testing of layered composite structures, through-wall and medical imaging require more advanced imaging systems and image reconstruction algorithms (post-processing) suitable for imaging inhomogeneous (i.e., layered) media. Currently-available imaging algorithms are not always robust, easy to implement, and fast. Synthetic aperture radar (SAR) techniques are some of the more prominent approaches for image reconstruction when considering low loss and homogeneous media. To address limitations of SAR imaging, when interested in imaging an embedded …

Topics In Voice Echo Cancellation, Pratik Vijay Shah

Doctoral Dissertations

"Acoustic echo cancellation (AEC) is a well studied problem. The underlying assumption in most echo cancellation solutions is that the echo path following the reference signal is completely linear. However, in many handheld devices, the echo path following the reference signal is nonlinear. The reason for this nonlinearity in the echo path is the use of smaller and cheaper loudspeakers. In order to cut the manufacturing cost, device manufactures use cheaper loudspeakers such that they satisfy the carrier specifications. Such loudspeaker can be easily over driven in to their nonlinear region and thus add nonlinearities to the downlink path. This …

Modeling And Analysis Of Dynamic Behavior Of Adsorption Stratified Column Beds Packed With Partially Fractal Porous Adsorbent Particles, Min Li

Doctoral Dissertations

"In this work novel porous adsorbent media having partially fractal structures and stratified packed-beds are constructed and their dynamic performance with respect to their adsorptive capacity through the construction and solution of rigorous models is studied. The results show that conventional columns packed with partially fractal porous adsorbent particles provide larger breakthrough times and dynamic utilization of the adsorptive capacity of the column when compared with those of conventional columns employing conventional adsorbent particles which do not possess a partially fractal structure. Furthermore, stratified column beds exhibit superior species separation performance than conventional columns when they are packed with either …