Engineering Commons^™

Femtosecond Laser Micromachining Of Microstructures For Sensing And Detection, Yukun Han

Doctoral Dissertations

"This thesis focuses on the fabrication and analysis of miniature functional devices that can be used for different sensing and detection applications. As the first step, the surface characteristics and morphology of the micro/nano structures on substrates (fused silica and silicon) fabricated in water and in air by femtosecond laser were investigated. Based on this study, three micro devices have been designed and fabricated by femtosecond laser, and they were analyzed for optical and chemical sensing and detections. The three micro devices are: 1) an optical Fabry-Perot interferometer in optical fiber (made from fused silica) with smooth cavity surfaces. The …

Impact Of Stochastic Loads And Generations On Power System Transient Stability, Theresa Odun-Ayo

Doctoral Dissertations

"Randomness in physical systems is usually ultimately attributed to external noise. Dynamic systems are driven not only by our own control inputs, but also disturbances which cannot be modeled deterministically. A linear system model is justifiable for a number of reasons, often such a model is adequate for the purpose at hand, and when non-linearities do exist, the typical engineering approach is to linearize about some nominal point or trajectory to achieve a perturbation or error model. However, in order for the resulting model to fit data generated by the real world, these disturbances need to be modeled stochastically. The …

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 …

Hardware Emulation Of Wireless Communication Fading Channels, Fei Ren

Doctoral Dissertations

"This dissertation investigates several main challenges to implementing hardware-based wireless fading channel emulators with emphasis on incorporating accurate correlation properties. Multiple-input multiple-output (MIMO) fading channels are usually triply-selective with three types of correlation: temporal correlation, inter-tap correlation, and spatial correlation. The proposed emulators implement the triply-selective fading Channel Impulse Response (CIR) by incorporating the three types of correlation into multiple uncorrelated frequency-flat Rayleigh fading waveforms while meeting real-time requirements for high data-rate, large-sized MIMO, and/or long CIR channels. Specifically, mixed parallel-serial computational structures are implemented for Kronecker products of the correlation matrices, which makes the best tradeoff between computational speed …

Approximate Dynamic Programming Solutions With A Single Network Adaptive Critic For A Class Of Nonlinear Systems, Jie Ding

Doctoral Dissertations

"Approximate dynamic programming formulation implemented with an Adaptive Critic (AC) based neural network (NN) structure has evolved as a powerful technique for solving the Hamilton-Jacobi-Bellman (HJB) equations. As interest in ADP and the AC solutions are escalating with time, there is a dire need to consider possible enabling factors for their implementations. A typical AC structure consists of two interacting NNs which is computationally expensive. In this work, a new architecture, called the "Cost Function Based Single Network Adaptive Critic (J-SNAC)" is presented that eliminates one of the networks in a typical AC structure. This approach is applicable to a …

Biodegradable Polymer/Clay Nanocomposites Based On Poly(Butylene Adipate-Co-Terephthalate) And Polylactide, Mahin Shahlari

Doctoral Dissertations

"In offering a scientifically succinct methodology which leads to property-enhanced biodegradable polymer products for broader application, as well as in promoting the use of bio-sourced renewable polymers such as Polylactide (PLA) in biodegradable polymers with desirable properties from petroleum based polymers such as PBAT, this study and its results both directly and indirectly contribute to the technological solutions that address growing environmental and energy problems caused by the increased use of and reliance upon nondegradable, nonrenewable, petroleum-based plastics. This work studied blends of PBAT and PLA compounded with organoclay through direct melt mixing in a twin-screw extruder and a batch …

Development Of A Fuel Cell Plug-In Hybrid Electric Vehicle And Vehicle Simulator For Energy Management Assessment, Andrew Meintz

Doctoral Dissertations

"This dissertation offers a description of the development of a fuel cell plug-in hybrid electric vehicle focusing on the propulsion architecture selection, propulsion system control, and high-level energy management. Two energy management techniques have been developed and implemented for real-time control of the vehicle. The first method is a heuristic method that relies on a short-term moving average of the vehicle power requirements. The second method utilizes an affine function of the short-term and long-term moving average vehicle power requirements. The development process of these methods has required the creation of a vehicle simulator capable of estimating the effect of …

Dynamic Ergonomic Analysis And Simulation Of Fastening Operation, Akul Joshi

Doctoral Dissertations

"Operator performing fastening operation with powered hand-tools at awkward postures is subjected to external forces that may pose a risk of developing ergonomic injuries. For design of safe workplaces and selection of tools it is necessary to identify the probable causes of discomfort by simulating the work conditions and quantifying the risk factors. An ergonomic simulator is developed to simulate the fastening operation and quantify the effects of posture and force in fastening operation. The effect of dynamic forces is analyzed using two approaches. The first approach analyzes the effect of tool vibration while the second analyzes the hand-arm system …

Leaching Characteristics Of Inorganic Contaminants From Coal Fly Ash, Tingzhi Su

Doctoral Dissertations

"Leaching of trace elements raises environmental concerns in coal fly ash disposal and reuse. US EPA is in the process of creating the first national rule on coal ash management. However, due to the complexity of coal fly ash composition, the leaching characteristics of trace elements are not well understood. Meanwhile, driven by the tightening emission regulations, new types of coal fly ashes are continuously generated as a result of the technological evolution at coal energy industry. The changing landscape highlights the needs for a comprehensive database to assess the leaching characteristics of different types of coal fly ashes, evaluation …

Sandwich Structures With Advanced Facings, Cody H. Nguyen

Doctoral Dissertations

"The purpose of this research is to investigate potential advantages of two innovative designs of sandwich panels. The first design involves sandwich panels with a piece-wise thickness of the facings aiming at two possible outcomes: (I) improved the structural response, i.e. strength and stiffness, without increasing the weight of the structure or (2) reduction in the weight of the structure without a detriment to its structural response. The analysis is conducted analytically using the first-order shear deformation theory and numerically by the finite element analysis of conventional and stepped-wise sandwich panels. The applicability of the first-order shear deformation theory to …

Processing And Characterization Of Boron Carbide-Hafnium Diboride Ceramics, Harlan J. Brown-Shaklee

Doctoral Dissertations

"Hafnium diboride based ceramics are promising candidate materials for advanced aerospace and nuclear reactor components. The effectiveness of boron carbide and carbon as HfB₂ sintering additives was systematically evaluated. In the first stage of the research, boron carbide and carbon additives were found to improve the densification behavior of milled HfB₂ powder in part by removing oxides at the HfB₂ surface during processing. Boron carbide additives reduced the hot pressing temperature of HfB₂ by 150⁰C compared to carbon, which reduced the hot pressing temperature by ~50⁰C. Reduction of oxide impurities alone could not explain the difference in sintering enhancement, however, …

Spiking Neural Networks And Their Applications, Cameron Eric Johnson

Doctoral Dissertations

"Artificial neural networks (ANNs) have been developed as adaptable, robust function approximators for at least the last quarter-century. They have progressed through two generations, and the third is now under development. Spiking neural networks (SNNs) seek to improve on previous generations in two ways: by using a more biologically-inspired neuron, they are shown to be capable of more complex calculations; incorporating polychronous properties of highly-recurrent networks with delays of different lengths on each synapse to achieve large numbers of possible patterns with relatively few neurons and synapses.

Abstracted spiking neurons have been used as a third-generation activation function in a …

Surface Modification Of Micro-Fluidic Devices, Zhan Gao

Doctoral Dissertations

"The surface modification, fabrication and characterization of microfluidic sensor systems for oxygen and glucose measurements with the use of polymeric materials were investigated in this dissertation. This dissertation is prepared in publication format. The first manuscript focuses on the surface modification of SU -8 layer to enhance the wettability. The improvement of wettability is critical since biofouling can be minimized during bioanalysis. A novel in situ photopattemable grafting technology was used to attach biocompatible polymer layers on SU-8 surface, changing its property from hydrophobicity to hydrophilicity. The results were confirmed by contact angle measurement and Fourier Transform Infrared (FTIR) spectra. …

Enhanced Heavy Oil Recovery By Alkali-Surfactant In The Pennsylvania Warner Sandstone, Rabia Mohamed Hunky

Doctoral Dissertations

"In this research, a study of the non-thermal method of alkaline-surfactant (AS) flooding to enhance heavy oil recovery from the Pennsylvanian Warner sandstone reservoir in Western Missouri was conducted. This work includ [sic] testing approximately 30 commercial surfactants and using a heavy oil sample with an API of 17. It was found that a number of surfactants could create stable emulsions. The viscosity of heavy oil could be reduced from 18,518 cp to 2.5 cp at 25⁰C through emulsification of certain surfactants. One of the major findings was that the emulsion created by the commercial surfactant, Igepalʼ CO-530 was stable …

Thermodynamic Approach To Fatigue Failure Analysis In Metals And Composite Materials, Mehdi Naderi Abadi

LSU Doctoral Dissertations

Fatigue is a dissipative process and must obey the laws of thermodynamics. In general, it can be hypothesized that the degradation of machinery components is a consequence of irreversible thermodynamic processes that disorder a component, and that degradation is a time dependent phenomenon with increasing disorder. This suggests that entropy —a fundamental parameter in thermodynamics that characterizes disorder— offers a natural measure of component degradation. The majority of the existing methods for prediction of fatigue are limited to the study of a single fatigue mode, i.e., bending or torsion or tension-compression. Further, the variability in the duty cycle in a …

Embedded Piezoelectric Fiber Composite Sensors For Applications In Composite Structures, Hari Prasad Konka

LSU Doctoral Dissertations

Health monitoring of the composite structures is an important issue that must be addressed. Embedded sensors could be an effective way to monitor the health of composite structures continuously and which could also avoid the catastrophic failures of composite structures. Piezoelectric-fiber-composite sensors (PFCS) made from micro-sized Lead Zirconate Titanate (PZT) fibers have great advantages over the traditional bulk PZT sensors for embedded sensor applications. PFCS as an embedded sensor will be an ideal choice to continuously monitor the stress/strain levels and health conditions of composites. This work presents a critical study on using PFCS as an effective embedded sensor within …

Characterization Of Novel Akermanite:Poly-E-Caprolactone Scaffolds For Bone Tissue Engineering Aapplications Combined With Human Adipose-Derived Stem Cells, Andre S. Zanetti

LSU Doctoral Dissertations

The development of porous materials useful as scaffolds for the sustained three-dimensional (3D) growth of human adipose-derived stem cells (hASC) is of particular interest to facilitate healing after musculoskeletal injuries. In this study, a composite porous material obtained by blending akermanite with poly-e-caprolactone (PCL) is proposed as novel alternative to bone tissue regeneration. The objectives of this study are (1) to characterize the akermanite:PCL scaffold properties; (2) to investigate the in vitro osteogenic potential of hASC loaded to optimal akermanite:PCL scaffolds; (3) to assess the metabolic activity and osteogenesis of hASC loaded to optimal akermanite:PCL scaffolds post-thawing using optimal cryopreservation …

Droplet Motion On Miniaturized Ratchets, Jeong Tae Ok

LSU Doctoral Dissertations

The main objective of this study is to evaluate the feasibility of using miniaturized asymmetric structures to move liquid droplets and understand the driving mechanism. We developed the fabrication process for large area topological ratchets with the period ranging from millimeter down to sub-micrometer using micromachining techniques. Non-wetting superhydrophobic surfaces were successfully fabricated using soft UV or thermal nanoimprint lithography, reactive ion etching by oxygen plasma, and chemical surface modification by fluorinated silane vapor deposition. An accurate and reproducible experimental setup equipped with high speed camera and automatic injection system was established. Image processing tools allowed us to obtain various …

The Effects Of Solidification Under Pressure On Properties Of Cast Aluminum Alloys, Santosh B. Ghanti

All ETDs from UAB

The mechanical properties of aluminum alloy castings are affected by porosity which is caused by a combination of dissolved gases and shrinkage. The objective of this research is to study the effects of solidification under pressure on microstructure and mechanical properties of two aluminum alloys, A356-T6 and A206-T6. Wedge-shaped aluminum castings were produced with chemically bonded sand molds. Castings were poured at 704ºC (1300ºF) or 760ºC (1400ºF) and solidified under 1 atmosphere or 10 atmospheres of applied pressure. Density, x-ray radiography, metallographic inspection, and tensile testing were performed on samples from various section sizes of the castings. For aluminum alloy …

Modeling Incident And Emergency Management From A Regional Perspective, Ozge Cavusoglu

All ETDs from UAB

Traffic incidents and natural or man-made disasters can impose significant safety risks and disruptions on traffic flows, often resulting in non-recurring congestion. Congestion, in turn, may impede the ability of EMS (Emergency Medical Services) to provide timely response to those in need of medical attention. Thus, it is important to understand the potential impacts of incidents and emergencies on traffic network operations and develop response strategies with a potential of minimizing such impacts on traffic operations, emergency response and the safety of the traveling public. The objective of the dissertation was twofold: a. Study incident management options and benefits from …

Multilayered Nanostructured Diamond Coatings For Temporomandibular Joint Prostheses, Leigh Booth

All ETDs from UAB

Disorders of the temporomandibular joint (TMJ) may lead to pain, discomfort and reduced function in many patients. When less invasive treatment methods have been exhausted, a TMJ prosthesis may be used to restore joint mobility and function. Currently available TMJ prosthesis designs feature metal-polyethylene or metal-on-metal wear couples; though these devices have been used to successfully restore joint function, the generation of wear debris may lead to adverse reactions at the implant site (such as inflammation or osteolysis). To further reduce wear and potentially increase the lifetime of these devices, nanostructured diamond (NSD) coatings on the articulating surfaces of Ti-6Al-4V …

Ultrasound Elasticity Measurements As A Predictor For Arteriovenous Fistula Maturation, Anna Sorace

All ETDs from UAB

This research thesis examines the applicability of using ultrasound imaging to quantify arterial elasticity and assess potential of arteriovenous fistula maturation in chronic kidney disease (CKD) patients. Tissue-specific abnormalities have proven useful for identifying disease states within oncology, cardiovascular and musculoskeletal system. Using ultrasound-based imaging to evaluate arterial elasticity is a noninvasive and novel technique. It has the potential to contribute further insight into chronic kidney disease fistula failure and become a noninvasive prognostic indicator. Reliable vascular access is critical for delivery of adequate hemodialysis treatment to CKD patients and to maintain long-term connections for dialysis. An arteriovenous fistula is …

Ionic Mechanism Of Post-Shock Arrhythmias: Role Of Intracellular Calcium, Brittany Sowell

All ETDs from UAB

Background: Defibrillation shocks are commonly used to interrupt life-threatening cardiac arrhythmias, but these strong electrical shocks may cause post-shock arrhythmias, the ionic mechanism of which is not well known. Strong shocks cause electroporation and diastolic Cai2+ increase, which may possibly lead to focal arrhythmias via spontaneous Cai2+ rise (SCR), activation of inward Na+-Ca2+ exchange current (INCX), and rise in membrane potential (Vm). The objective of this study was to examine the role of intracellular calcium and the Cai2+-dependent ionic mechanism in post-shock arrhythmias. Methods: Experiments were performed in patterned cultures of neonatal rat myocytes. Fluorescent dyes and two 16x16 photodiode …

Osteogenic Differentiation Of Human Mesenchymal Stem Cells Enhanced By Bone Ecm Analogous Nanomatrix Composites, Jeremy Benton Vines

All ETDs from UAB

A growing trend in the area of bone tissue engineering is the development of materials that mimic the native bone extracellular matrix (ECM). This need is typically met through the creation of composites, which attempt to recapitulate both the organic and inorganic components of the native bone ECM. However, few composites have been created with organic ECM analogous components that are functionalized to direct cellular behaviors. Furthermore, a majority of these studies do not investigate how the ratio of the inorganic and organic components affects cellular behaviors. To address this issue, hydroxyapatite nanoparticles (HANPs) were dispersed within peptide amphiphile (PA) …

Hole Patching In Unstructured Mesh And Parallelization Using Graphics Processing Units, Amitesh Kumar

All ETDs from UAB

Engineering analysis of a three-dimensional geometric model using mesh-based computational technologies requires the model to be topologically watertight. However, achieving watertight geometry is considered to be a challenging task in the field of computational engineering due to the potential presence of geometric deficiencies, such as gaps and holes on the surfaces. This dissertation aims to repair the defective geometric model with the presence of holes irrespective of their complexities. Presented in this dissertation are novel research and implementation of a hybrid surface and volume-based technique for geometry repair. It utilizes a NURBS-based surface-patching algorithm for topologically simple holes and incorporates …

Functional Imaging Of Excitable Cells: Retinal Neurons And Pancreatic Islet Beta Cells, Yichao Li

All ETDs from UAB

Stimulus-evoked fast intrinsic optical signals (IOSs) have time courses comparable to electrophysiological kinetics, and thus promise a sub-cellular and sub-second resolution method for functional evaluation of excitable biological tissues. The objective of my thesis research is to validate and characterize IOS imaging of stimulus-evoked activities in the retina and pancreatic islet ß-cells. In order to achieve this objective, three sets of experiments have been conducted. 1) Simultaneous measurement of retinal neurons functioning can enhance our understanding of the visual signal processing. In this stage of my study, I propose to demonstrate IOS imaging of retina slices that allows simultaneous monitoring …

Optimal Bracing Type And Layouts To Minimize Lateral Drift In High-Rise Steel Framed Buildings Subjected To High Winds Using Sap2000, Nicholas Francis Mcewen

All ETDs from UAB

OPTIMAL BRACING TYPE AND LAYOUTS TO MINIMIZE LATERAL DRIFT IN HIGH-RISE STEEL FRAMED BUILDINGS SUBJECTED TO HIGH WINDS USING SAP2000 NICHOLAS F. MCEWEN Civil, Const. & Environmental Engineering (ABSTRACT) As cost controls almost all projects and wind forces typically control the design of high-rise buildings, it is crucial to understand the most optimal use of steel when concerning protection against lateral forces. One of the largest tasks of the designer in highrise building design simply reduces to limiting the lateral drift that is associated with wind forces. Thus, the primary objective of this research was to use the SAP2000 software …

Design Space Decomposition Using Concept Maps, David E. Robbins

All ETDs from UAB

Decomposition of engineering design spaces has been performed primarily through statistical and system identification techniques. However, no approach has yet attempted to capture the semantics of a design through decomposition. This thesis presents graphical techniques for capturing the semantics of a design by developing an information architecture through design space decomposition using concept maps. In particular, concept maps are used to begin identifying the top layers of the information architecture of a problem, which has the dual effects of performing an initial decomposition of the design space and refining the parameters that will define more detailed design spaces for further …

Parallel Confocal Recording Of Localized Retinal Photoreceptor Responses, Qiuxiang Zhang

All ETDs from UAB

The primary purpose of my thesis research is to validate parallel confocal recording of intrinsic optical signals (IOSs) correlated with localized retinal photoreceptor responses. IOS imaging promises a noninvasive method for retinal disease detection and treatment evaluation. However, IOS identification of localized retinal dysfunction is still challenging due to the complexity of retinal structure. Stimulus-evoked IOSs have been observed in both photoreceptors and inner retinal neurons. IOS pattern of retinal photoreceptor layer may contain cross-talk noise from inner retinal layers. In order to detect localized retinal photoreceptors response without significant contamination from other retinal volumes, we designed a rapid functional …

Cyclic Elongation And Pull Out Of Unicortical And Bicortical Suture Anchor Designs, Richard Justin Lesley

All ETDs from UAB

CYCLIC ELONGATION AND PULL OUT OF UNICORTICAL AND BICORTICAL SUTURE ANCHOR DESIGNS JUSTIN LESLEY BIOMEDICAL ENGINEERING ABSTRACT A novel suture anchor design was introduced and biomechanically tested. The novel design involved lengthening a standard metal screw type anchor so as to achieve greater fixation in bone. Along with utilizing a greater amount of trabecular bone, this design also allows a second layer of cortical bone to be involved in order to further enhance fixation. This "bicortcal" design is intended to be used under unique clinical circumstances. Such circumstances may include RC repair in patients with extreme osteoporosis, in cases where …