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Articles 1 - 30 of 39
Full-Text Articles in Engineering
The Development Of A Mesenchymal Stem Cell Based Bone Graft System, Sarina Sinclair
The Development Of A Mesenchymal Stem Cell Based Bone Graft System, Sarina Sinclair
All Dissertations
Greater than 5.5 million fractures are sustained by Americans each year, accounting for more than 500,000 bone graft surgeries. Bone grafts are the second most transplanted material, surpassed only by blood. The current 'gold standard' for bone grafting involves harvesting bone material from the patient's iliac crest, due to its osteoinductive properties. Unfortunately, the surgery required to harvest material from the iliac crest causes additional pain for the patient, relies on a limited amount of available bone tissue, and results in, on average, a 30% rate of donor site morbidity. Both natural and synthetic substitutes have been developed to avoid …
Dynamics Of Ultrasonic Consolidation, James Gibert
Dynamics Of Ultrasonic Consolidation, James Gibert
All Dissertations
Ultrasonic consolidation (UC) is a solid state rapid manufacturing process derived from ultrasonic welding of thin metal foils coupled with contour milling to achieve functional accurate components. The bonding of metal is accomplished by the local application of high frequency vibration energy under pressure producing a metallurgical bond without melting the base material. Its unique nature allows the design and fabrication of structural panels for satellites, production of injection molding tools, functionally graded structures, metal-matrix composites, embedded sensors, armor, and fiber embedded adaptive structures. It is commonly theorized that interfacial motion and friction at the bonding interface play a prominent …
Hydrogel Compositions For Nonviral Gene Delivery, Eunhee Cho
Hydrogel Compositions For Nonviral Gene Delivery, Eunhee Cho
All Dissertations
The incorporation of nonviral vectors into biomaterial matrices has been employed to improve localization at the implant site and to protect from loss by clearance or extracellular barriers. However, several limitations such as detrimental crosslinking mechanisms, uncontrolled burst release require improved design of matrix-based gene delivery systems that provides sustained and controlled vector release as well as overcomes extracellular barriers to gene transfer in proximity to target cells. The long-term objective of this dissertation project is to provide the basis for the eventual creation of tissue engineering scaffolds that combine structural and biological activity through the creation of composite materials …
Human Error In Mining: A Multivariable Analysis Of Mining Accidents/Incidents In Queensland, Australia And The United States Of America Using The Human Factors Analysis And Classification System Framework, Jessica Patterson
All Dissertations
Historically, mining has been viewed as an inherently high-risk industry. Nevertheless, the introduction of new technology and a heightened concern for safety has yielded marked reductions in accident and injury rates over the last several decades. In an effort to further reduce these rates, the human factors associated with incidents/accidents need to be addressed. A modified version of the Human Factors Classification and Analysis System (HFCAS-MI) was used to analyze lost time accidents and high-potential incidents from across Queensland, Australia and fatal accidents from the United States of America (USA) to identify human factor trends and system deficiencies within mining. …
Nucleation And Growth Behavior Of Tellurite-Based Glasses Suitable For Mid-Infrared Applications, Jonathan Massera
Nucleation And Growth Behavior Of Tellurite-Based Glasses Suitable For Mid-Infrared Applications, Jonathan Massera
All Dissertations
Optical fibers transmitting in the 2-5 μm mid-infrared (MIR) spectral region are highly desirable for a variety of military and civilian applications including super-continuum generation, infrared countermeasures (IRCM), and MIR laser sources. These new applications in the mid-infrared require novel optical materials that transmit in this window and can be fabricated into fiber. As tellurite glasses are known to have good transparency in the (NIR) region, tellurite-based glasses are the material of choice for this study due to their high linear and nonlinear refractive index, their low glass transition temperature and the ability to form them into optical fiber.
This …
A Scanpath Comparison Of The Salient Features Of Weather Among General Aviation Pilots Based On Training And Experience, Michael Sawyer
A Scanpath Comparison Of The Salient Features Of Weather Among General Aviation Pilots Based On Training And Experience, Michael Sawyer
All Dissertations
Over the last 20 years the number of annual accidents in general aviation has seen a steady decline. The annual number of fatal accidents, however, has remained relatively stable. Adverse weather is consistently cited as a leading cause of fatal accidents in general aviation; weather accidents have a fatality rate nearly four times that of other general aviation accidents. Reviews of accident data reveal that often these accidents occur when inexperienced pilots who are certified only for visual flight rules flight continue into adverse weather. The Situation Assessment Hypothesis suggests these accidents occur when pilots fail to accurately recognize weather …
Laboratory Generation And Physics Of Propagation Of Solitary Waves And Water Surface Depressions, Siamak Malek Mohammadi
Laboratory Generation And Physics Of Propagation Of Solitary Waves And Water Surface Depressions, Siamak Malek Mohammadi
All Dissertations
Solitary waves and water surface depressions are generated using a piston-type wavemaker. Different aspects of their propagation including profile evolution, establishment rate, stability, and celerity are examined experimentally.
Traditionally, solitary waves are generated in laboratory set-ups using a methodology developed by Goring (1979) that considers a wave of permanent form during the generation process. A New methodology for generation of solitary waves using piston-type wavemakers is proposed by considering the evolving nature of the wave during generation phase. The capability of the New methodology in generation of solitary waves is assessed by conducting a series of laboratory experiments in water …
Inter-Tube Bonding And Defects In Carbon Nanotubes And The Impact On The Transport Properties And Micro-Morphology, Keqin Yang
All Dissertations
The transport properties of the carbon nanotubes (CNTs) are affected by the tube-tube interaction and the defects presented in the system. Inter-tube bonding, formed during spark plasma sintering (SPS) process, lowers the electrical/thermal resistivity at the tube-tube junctions and also causes new scattering mechanisms such as strong electron-phonon coupling (EPC) at low temperature. More evidences have been found by changing the SPS temperature and doping the CNTs to support the electron-phonon coupling is Kohn anomaly (KA) in as-SPSed CNTs. The phonon drag, appearing in thermoelectric power (TEP) of the as-SPSed CNTs at low temperature, can be explained in the framework …
Covalent Immobilization Of L1 Neural Cell Adhesion Molecule To Acrylated Tetronicâ® Hydrogels For Neural Regeneration, Rebecca Cribb
Covalent Immobilization Of L1 Neural Cell Adhesion Molecule To Acrylated Tetronicâ® Hydrogels For Neural Regeneration, Rebecca Cribb
All Dissertations
Spinal cord injuries cost the United States $20 billion per year, with an existing patient population of 256,000 growing by an estimated 12,000 each year. Current clinical therapies for spinal cord injury are limited to spinal immobilization and realignment via traction, surgery, administration of methylprednisolone sodium succinate (MPSS) within eight hours post-injury, and rehabilitation exercises. While these therapies are important and may minimize damage and restore limited function, there is a dire clinical need for treatments to address the growing population of chronically-injured patients.
Varying degrees of axonal regeneration and functional recovery following spinal cord injury have been achieved in …
Creation Of Bioactive Surfaces To Modulate Cell Behavior Using Surface Initiated Photoiniferter-Mediated Graft Photopolymerization, Nihar Shah
All Dissertations
Biomaterials widely used in biomedical applications still face biocompatibility issues arising from non-specific protein adsorption on the foreign surface, and the consequent undesired cell response. Emerging evidence suggests that imparting specific bioactivity to the biomaterial's surface to elicit favorable response from cells, (like osseointegration of joint implants and endothelialization of stents) can yield much better biocompatibility results when combined with passive prevention of protein adsorption. In more complex diseases like spinal cord injury and cardiomyopathy, specific biomolecules are required to elicit desired cell responses for successful regeneration. However, for success of such biomolecule based strategies, the effects of various parameters …
Real-Time Vehicle Parameter Estimation And Adaptive Stability Control, John Limroth
Real-Time Vehicle Parameter Estimation And Adaptive Stability Control, John Limroth
All Dissertations
This dissertation presents a novel Electronic Stability Control (ESC) strategy that is capable of adapting to changing vehicle mass, tire condition and road surface conditions. The benefits of ESC are well understood with regard to assisting drivers to maintain vehicle control during extreme handling maneuvers or when extreme road conditions such as ice are encountered. However state of the art ESC strategies rely on known and invariable vehicle parameters such as vehicle mass, yaw moment of inertia and tire cornering stiffness coefficients. Such vehicle parameters may change over time, especially in the case of heavy trucks which encounter widely varying …
Production And Characterization Of Novel Shaped Fibers For Fluid Sorption And Transport, Lisa Fuller
Production And Characterization Of Novel Shaped Fibers For Fluid Sorption And Transport, Lisa Fuller
All Dissertations
This work investigated the production and characterization of novel shaped fibers for fluid adsorption and transport. Shaped fibers such as Y, H, and octolobal, as well as conventional round fibers, were extruded using a research melt extruder. The fibers were extruded from 18 melt flow index (MFI) polypropylene (PP) and blends of 18 MFI PP and 400 MFI PP. Hydrophilic spin finish Bozzetto Favorol SF2 was applied to the surface of extruded fibers and hydrophilic polyester additive LB-100 was included in the blend of some H fibers to increase the hydrophilicity of the fiber surface. The geometric shape retention of …
Synthesis And Spectroscopic Characterization Of Nanostructured Thermoelectric Materials, Jason Reppert
Synthesis And Spectroscopic Characterization Of Nanostructured Thermoelectric Materials, Jason Reppert
All Dissertations
Bismuth in the bulk form is a semimetal with a rhombohedral structure. It has a small band overlap between the conduction and valence bands and a highly anisotropic electron effective-mass tensor. Thermoelectric materials, in which one of the three dimensions is in the nanometer regime, exhibit unique quantum confinement properties and have generated much interest in recent years. Theoretical investigations have suggested that nanowires with diameters ≤ 10 nm will possess a figure-of-merit ZT > 2. Prior to this study, it has been shown that Bi nanowires with small enough diameters (~10 nm), prepared via the pulsed laser vaporization method, undergo …
Probabilistic Remediation Evaluation Model For Chlorinated Solvents Considering Uncertainty, Hailian Liang
Probabilistic Remediation Evaluation Model For Chlorinated Solvents Considering Uncertainty, Hailian Liang
All Dissertations
The complex processes and expensive costs of source and plume remediation of dense, non-aqueous phase liquid (DNAPL) complicate the decision-making process for site remediation. Selection of remediation alternatives has been a big challenge due to the lack of tools that simultaneously evaluate the effectiveness of source and plume remediation and access the uncertainties in all major parameters. In this research, a new probabilistic remediation model, Probabilistic Remediation Evaluation Model for Chlorinated solvents sites (PREMChlor), has been developed. This is achieved through linking the analytical model REMChlor to a Monte Carlo modeling simulation package GoldSim via a FORTRAN Dynamic Link Library …
Efficient Analysis Of Loaded Cylindrical Monopole Antennas, Adam Schreiber
Efficient Analysis Of Loaded Cylindrical Monopole Antennas, Adam Schreiber
All Dissertations
In this dissertation is presented a collection of papers focusing on enhancing the efficiency of integral equation solutions of antennas. A method of incorporating network principles into the method of moments is developed. Scattering parameters are determined for two structures: a coaxial-guide/radial-guide junction present in coaxial feeds of monopole and dipole antennas, and a folded coaxial guide junction proposed as part of an inductive load below the feed of the antenna. There is excellent agreement among the data obtained from the proposed method, independent MoM solutions not incorporating network principles, and measurements. An investigation into electrically switching a folded coaxial …
Wide Area Monitoring And Control, Manish Patel
Wide Area Monitoring And Control, Manish Patel
All Dissertations
Today's interconnected power system is deregulated for wholesale power transfers. In 1996 Federal Energy Regulatory Commission provided open access of the transmission network to utilities. Since then utilities are transferring power over long distances to bring reliable and economical electric supply to their customers. As the number of wholesale power transactions taking place over an interconnected system are increasing, system operators in control areas are forced to monitor the grid on a large scale to operate it reliably. Before scheduling such a large scale power transactions, it is necessary to make sure that such transaction will not violate system operating …
The Rheology, Degradation, Processing, And Characterization Of Renewable Resource Polymers, Jason Conrad
The Rheology, Degradation, Processing, And Characterization Of Renewable Resource Polymers, Jason Conrad
All Dissertations
Renewable resource polymers have become an increasingly popular alternative to conventional fossil fuel based polymers over the past couple decades. The push by the government as well as both industrial and consumer markets to go 'green' has provided the drive for companies to research and develop new materials that are more environmentally friendly and which are derived from renewable materials. Two polymers that are currently being produced commercially are poly-lactic acid (PLA) and polyhydroxyalkanoate (PHA) copolymers, both of which can be derived from renewable feedstocks and have shown to exhibit similar properties to conventional materials such as polypropylene, polyethylene, polystyrene, …
An Investigation On The Use And Flexibility Of Genetic Algorithms For Logistic Regression, Sara Yoder
An Investigation On The Use And Flexibility Of Genetic Algorithms For Logistic Regression, Sara Yoder
All Dissertations
Social scientists and other users of large data sets often desire a model to predict the probability that some condition exists, such as the probability that a person has diabetes or that a credit card transaction will be fraudulent. In general, this can be done by data mining techniques, which allow multiple records of data composed of numerous independent variables and one dependent variable to be examined in a statistical fashion to make a predictive model. One particular technique used is logistic regression. Logistic regression forms a predictive model based on a set of independent variables by assigning coefficients to …
Evaluation Of Fluid Diodes As Pulmonary Heart Valve Replacements, Tiffany Camp
Evaluation Of Fluid Diodes As Pulmonary Heart Valve Replacements, Tiffany Camp
All Dissertations
Children born with congenital heart disease often times suffer from severe chronic pulmonary insufficiency. Palliative treatments for this condition may come early on in the life of the patient; however, if it becomes severe enough, a pulmonary valve replacement may be required. There currently is not a permanent option for a replacements valve. Therefore, a need exists to develop a permanent solution. Knowing that the right heart circulation is more tolerant of moderate levels of regurgitation (0 - 35%) and pressure gradient (0 - 30 mmHg), this study investigates the hypothesis that a fluid diode, a motionless valve that offers …
Motion Segmentation From Clustering Of Sparse Point Features Using Spatially Constrained Mixture Models, Shrinivas Pundlik
Motion Segmentation From Clustering Of Sparse Point Features Using Spatially Constrained Mixture Models, Shrinivas Pundlik
All Dissertations
Motion is one of the strongest cues available for segmentation. While motion segmentation finds wide ranging applications in object detection, tracking, surveillance, robotics, image and video compression, scene reconstruction, video editing, and so on, it faces various challenges such as accurate motion recovery from noisy data, varying complexity of the models required to describe the computed image motion, the dynamic nature of the scene that may include a large number of independently moving objects undergoing occlusions, and the need to make high-level decisions while dealing with long image sequences. Keeping the sparse point features as the pivotal point, this thesis …
Colloidal Electroluminescence: Novel Routes To Controlled Emission Of Organic Light Emitting Diode Devices, Christopher Huebner
Colloidal Electroluminescence: Novel Routes To Controlled Emission Of Organic Light Emitting Diode Devices, Christopher Huebner
All Dissertations
In recent years the importance of the organic light emitting diode (OLED) has grown immensely, and the past two decades have seen ongoing and exhaustive research in organic routes to solid state lighting,
wherein electricity is directly converted into emitted light through an excited state relaxation mechanism. The benefits of incorporating polymeric and small molecule materials into solid state lighting devices include high efficiences, low production costs, amenability to large-scale production and devices, reduced environmental impact and low energy consumption. Herein are presented novel routes to materials engineering and preparation, device fabrication and emission tailoring through the abilility to form …
Lyapunov-Based Coordinated Control Of An Underactuated Unmanned Aerial Vehicle And Robot Manipulator, Dongbin Lee
Lyapunov-Based Coordinated Control Of An Underactuated Unmanned Aerial Vehicle And Robot Manipulator, Dongbin Lee
All Dissertations
This Ph.D. dissertation describes nonlinear tracking control results for a quadrotor helicopter unmanned aerial vehicle (UAV) towards the ultimate goal of controlling a combined UAV plus robot manipulator system (UAVRM). The quadrotor UAV is a helicopter that has four independent rotors that provide vertical lift: these four independent forces are managed in order to directly provide lift, pitch, roll, and yaw of the vehicle. Horizontal translations result from pitch and roll actions, the system is underactuated in the sense that there are only four control inputs to move the six degree-of-freedom aircraft. There are exising dynamic models of the quadrotor …
Development And Integration Of Geometric And Optimization Algorithms For Packing And Layout Design, Santosh Tiwari
Development And Integration Of Geometric And Optimization Algorithms For Packing And Layout Design, Santosh Tiwari
All Dissertations
The research work presented in this dissertation focuses on the development and application of optimization and geometric algorithms to packing and layout optimization problems. As part of this research work, a compact packing algorithm, a physically-based shape morphing algorithm, and a general purpose constrained multi-objective optimization algorithm are proposed. The compact packing algorithm is designed to pack three-dimensional free-form objects with full rotational freedom inside an arbitrary enclosure such that the packing efficiency is maximized. The proposed compact packing algorithm can handle objects with holes or cavities and its performance does not degrade significantly with the increase in the complexity …
Moisture Susceptibility Of Asphalt Mixes Using Phosphonylated Recycled Polyethylene, David Herndon
Moisture Susceptibility Of Asphalt Mixes Using Phosphonylated Recycled Polyethylene, David Herndon
All Dissertations
ABSTRACT
Today's asphaltic concrete pavements are expected to perform better even though they are experiencing increased volume of traffic and increased loads over what has been experienced in the past. Research has indicated that the addition of polymers to asphalt binders can enhance many properties of the asphalt pavements to help meet these increased demands.
There remains a serious problem that the addition of polymers to asphalt binders generally does not address. This involves the interfacial cohesiveness of the bond between the aggregate and the binder. Some aggregates are highly hydrophilic (water-loving) while asphalt binders and most polymers tend to …
Novel Techniques For The Synthesis Of Three-Way Catalytic Converter Support Materials, Prince Anyaba
Novel Techniques For The Synthesis Of Three-Way Catalytic Converter Support Materials, Prince Anyaba
All Dissertations
Current automobiles use catalytic converters, consisting of noble metals on an oxide support, to convert noxious engine exhaust pollutants into less harmful species. The development of mesoporous oxide supports with optimal pore geometries could enable these devises to decrease in size and weight and significantly reduce the metal loadings required to achieve optimal performance. Thus, in this work, I investigated a wide range of techniques for the synthesis of mesoporous oxides to determine if they could be adapted to ceria-zirconia-yttria mixed oxide (CZY) systems, which are the industry standard for the optimal oxide support for catalytic converter applications. Additionally, I …
Creation Of Defined Single Cell Resolution Neuronal Circuits On Microelectrode Arrays, Russell Pirlo
Creation Of Defined Single Cell Resolution Neuronal Circuits On Microelectrode Arrays, Russell Pirlo
All Dissertations
The way cell-cell organization of neuronal networks influences activity and facilitates function is not well understood. Microelectrode arrays (MEAs) and advancing cell patterning technologies have enabled access to and control of in vitro neuronal networks spawning much new research in neuroscience and neuroengineering. We propose that small, simple networks of neurons with defined circuitry may serve as valuable research models where every connection can be analyzed, controlled and manipulated.
Towards the goal of creating such neuronal networks we have applied microfabricated elastomeric membranes, surface modification and our unique laser cell patterning system to create defined neuronal circuits with single-cell precision …
Synthesis And Polymorphic Control For Visible Light Active Titania Nanoparticles, Sujaree Kaewgun
Synthesis And Polymorphic Control For Visible Light Active Titania Nanoparticles, Sujaree Kaewgun
All Dissertations
Titania (TiO2) is useful for many applications in photocatalysis, antimicrobials, pigment, deodorization, and decomposition of harmful organics and undesirable compounds in the air and waste water under UV irradiation. Among the three phases of TiO2, Rutile, Anatase, and Brookite, studies have been more focused on the anatase and rutile phases.
Pure brookite is the most difficult phase to prepare, even under hydrothermal conditions. Predominantly brookite phase TiO2 nanoparticles were prepared by the Water-based Ambient Condition Sol (WACS) process in our laboratory. The objectives of this research were to enhance visible light active (VLA) photocatalytic properties …
Surface And Bulk Modification Of Poly(Lactic Acid), Rahul Rasal
Surface And Bulk Modification Of Poly(Lactic Acid), Rahul Rasal
All Dissertations
The major drawbacks of PLA are its poor toughness and lack of readily reactable groups. Unfortunately, typical methods of PLA toughening are associated with significant modulus and/or ultimate tensile strength (UTS) loss. The main objective of this research was to toughen PLA, with minimal modulus and/or UTS loss, and introduce reactive groups into the PLA matrix in one step. Initially, this objective was divided into two separate parts: PLA surface modification followed by toughening.
PLA film was solvent cast from chloroform solution and was surface modified using a sequential two-step photografting approach. Benzophenone was photografted onto the film surface in …
An Examination Of Confined Aquifer Gradient Behavior Under Pumping Conditions, Stefanie Fountain
An Examination Of Confined Aquifer Gradient Behavior Under Pumping Conditions, Stefanie Fountain
All Dissertations
Accurate and reliable estimates of groundwater flow and contaminant transport models are dependent on an understanding of the aquifer properties used to create the models. The borehole flowmeter has been used with increasing frequency at a variety of sites to produce high resolution vertical hydraulic conductivity (K(z)) distributions [Boggs et al. 1990; Rehfeldt et al. 1989b; Molz et al. 1989, Boman et al. 1997; Dinwiddie et al. 1999]. In theory, the validity of measurements obtained using borehole flowmeters is contingent on the hydraulic head gradients near the well at each discrete depth resulting from the pumping-induced flow having reached quasi-steady-state. …
Development Of Strategies For Enhanced In Situ Bioremediation Of High Concentrations Of Halogenated Methanes, Huifeng Shan
Development Of Strategies For Enhanced In Situ Bioremediation Of High Concentrations Of Halogenated Methanes, Huifeng Shan
All Dissertations
ABSTRACT
Bioremediation of high concentrations of halomethanes e.g., carbon tetrachloride (CT), trichlorofluoromethane (CFC-11) and chloroform (CF) has seldom been addressed before and remains highly challenging. A microcosm study was conducted to investigate bioremediation strategies for groundwater contaminated with CT (6 to 10 mg/L), CFC-11 (1 to 26 mg/L), CF (3-500 mg/L), and 1,1-dichloroethene (1,1-DCE; up to 9 mg/L) at a former industrial site in California. Biostimulation with corn syrup and catalytic amounts of vitamin B12 was demonstrated as a feasible remedial strategy and bioaugmentation with B12 represents the most promising bioremediation method of the ones studied. Halomethane transformation …