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Articles 6811 - 6840 of 11510
Full-Text Articles in Engineering
Schmidtea Mediterranea Planaris As A Novel Animal Model For Investigating The Dynamics Of Nervous System Development In Fetal Alcohol Spectrum Disorder, Jesse Lowe
Theses and Dissertations
Fetal Alcohol Spectrum Disorder (FASD) is a prevalent developmental disease that is caused by excess in utero exposure to ethanol. The importance of timing and dosage of ethanol has been elucidated by previous investigations conducted with humans, rodents, and other model organisms, but challenges associated with determining functional deficiencies have necessitated the introduction of a novel animal model for investigating the dynamics of FASD. In this thesis, we propose that the freshwater flatworm planarian species, Schmidtea mediterranea, has the capability to fulfill this need. Planaria have the ability to completely regenerate fragments into intact, functional animals, and in these studies, …
Real-Time Target Following Using An Unmanned Rotorcraft With A Laser Rangefinder, Bryce Sanders Pincock
Real-Time Target Following Using An Unmanned Rotorcraft With A Laser Rangefinder, Bryce Sanders Pincock
Theses and Dissertations
Micro-unmanned aerial rotorcraft are quickly gaining acceptance as indoor platforms for performing stealth, surveillance, and rescue and reconnaissance missions. These rotorcraft are generally required to operate in cluttered, unknown, and dynamic GPS-denied environments, which present threats to the safe operation of the vehicle. To overcome these environmental challenges, we describe a system that is capable of localizing itself by producing accurate odometry estimates that can detect and track moving objects and avoid collisions with obstacles while following a moving target using a laser range finder. Our system has been implemented in the Simulink environment in MATLAB. Various simulations have shown …
Understanding Noble Metal Addition In Cobalt Fischer Tropsch Catalysts, Kari Marie Cook
Understanding Noble Metal Addition In Cobalt Fischer Tropsch Catalysts, Kari Marie Cook
Theses and Dissertations
The effects of noble metal (NM) promotion and deposition order (co-deposition of NM with the final Co deposition [co-dep] or sequential deposition of NM after Co deposition [seq-dep]) on surface area, pore size, metal retention, crystallite size, noble metal distribution and bonding in Co Fischer Tropsch (FT) catalysts were studied as were the resulting Co reducibility and Fischer Tropsch activity/selectivity properties. Catalysts containing nominally 25wt% Co with either 0.3 wt% Ru, 0.58 wt% Pt, 0.55wt% Re, or no NM on a La-stabilized-Al2O3 support were prepared by wet deposition. The Co, Pt, and Re were uniformly dispersed, but Ru distribution and …
A Study Towards Development Of An Automated Haptic User Interface (Ahui) For Individuals Who Are Blind Or Visually Impaired, Ravi Rastogi
A Study Towards Development Of An Automated Haptic User Interface (Ahui) For Individuals Who Are Blind Or Visually Impaired, Ravi Rastogi
Theses and Dissertations
An increasing amount of information content used in schools, work and everyday living is being presented in graphical form, creating accessibility challenges for individuals who are blind or visually impaired, especially in dynamic environments, such as over the internet. Refreshable haptic displays that can interact with computers can be used to access such information tactually. Main focus of this study was the development of specialized computer applications allowing users to actively compensate for the inherent issues of haptics when exploring visual diagrams as compared to vision, which we hypothesized, would improve the usability of such devices. An intuitive zooming algorithm …
The Effect Of Friction Stir Welding Process Parameters On Charpy V-Notch Impact Toughness In Hsla-65, Samuel C. Sanderson
The Effect Of Friction Stir Welding Process Parameters On Charpy V-Notch Impact Toughness In Hsla-65, Samuel C. Sanderson
Theses and Dissertations
HSLA-65 steel (6.4 mm thick) was friction stir welded at various welding speeds and spindle speeds. Varying weld parameters provided a range of heat inputs. Impact toughness was evaluated as a function of the different weld parameters and corresponding weld heat inputs. Charpy V-Notch (CVN) tests were conducted in parent material and at both the weld nugget centerline and heat-affected zone (HAZ) locations. The upper shelf CVN impact energy of the weld nugget was above that of the base metal for all weld parameters. The upper shelf impact toughness in the HAZ was largely unaffected by changing weld parameters. The …
Using Motion Fields To Estimate Video Utility And Detect Gps Spoofing, Brandon T. Carroll
Using Motion Fields To Estimate Video Utility And Detect Gps Spoofing, Brandon T. Carroll
Theses and Dissertations
This work explores two areas of research. The first is the development of a video utility metric for use in aerial surveillance and reconnaissance tasks. To our knowledge, metrics that compute how useful aerial video is to a human in the context of performing tasks like detection, recognition, or identification (DRI) do not exist. However, the Targeting Task Performance (TTP) metric was previously developed to estimate the usefulness of still images for DRI tasks. We modify and extend the TTP metric to create a similar metric for video, called Video Targeting Task Performance (VTTP). The VTTP metric accounts for various …
The Extraction Of Shock Waves And Separation And Attachment Lines From Computational Fluid Dynamics Simulations Using Subjective Logic, Matthew C. Lively
The Extraction Of Shock Waves And Separation And Attachment Lines From Computational Fluid Dynamics Simulations Using Subjective Logic, Matthew C. Lively
Theses and Dissertations
The advancement of computational fluid dynamics to simulate highly complex fluid flow situations have allowed for simulations that require weeks of computation using expensive high performance clusters. These simulations often generate terabytes of data and hinder the design process by greatly increasing the post-processing time. This research discusses a method to extract shock waves and separation and attachment lines as the simulation is calculating and as a post-processing step. Software agents governed by subjective logic were used to make decisions about extracted features in converging and converged data sets. Two different extraction algorithms were incorporated for shock waves and separation …
Lateral Resistance Of Piles Near Vertical Mse Abutment Walls, Jacob S. Price
Lateral Resistance Of Piles Near Vertical Mse Abutment Walls, Jacob S. Price
Theses and Dissertations
Full scale lateral load tests were performed on five piles located at various distances behind MSE walls. Three of the five test piles were production piles used to support bridges, and the other two piles were located behind a MSE wing walls adjacent to the bridge abutment. The objective of the testing was to determine the effect of spacing from the wall on the lateral resistance of the piles and on the force resisted by the MSE reinforcement. Tentative curves have been developed showing p-multiplier vs. normalized spacing behind wall for a length to height ratio of 1.1 and 1.6. …
Piezoelectric Probes And Their Capacity To Monitor Time Varying Viscosity, Eman Ahmed
Piezoelectric Probes And Their Capacity To Monitor Time Varying Viscosity, Eman Ahmed
Theses and Dissertations
Real-time, bedside observation of patient clotting is essential in various surgeries in the operating room (OR), but specifically during cardiac surgeries. The objective of this thesis is to design and test a new piezoelectric device that can be used for viscoelasticity measurement with time as a Point of Care (POC) test. Slow turnaround times (TAT) of current methods to monitor blood viscoelastic changes in patients have led to excessive bleeding and the need for blood transfusions in many situations (Despotis et al, 1997). This study shows that the phase shift produced by a resonator sensor can be related to the …
Study On The Fracture Toughness Of Friction Stir Welded Api X80, Allan M. Tribe
Study On The Fracture Toughness Of Friction Stir Welded Api X80, Allan M. Tribe
Theses and Dissertations
High strength low alloy (HSLA) steels have been developed to simultaneously have high yield strength and high fracture toughness. However, in practical applications steel must be welded. Traditional arc welding has proven detrimental to the fracture toughness of HSLA steels. Friction stir welding has recently shown mixed results in welding HSLA steels. The range of welding parameters used in these recent studies however has been very limited. With only a few welding parameters tested, the effect of spindle speed, travel speed, and heat input on the fracture toughness of friction stir welded HSLA steel remains unknown. To understand how the …
Integrated Fiber Electrospinning: Creating Spatially Complex Electrospun Scaffolds With Minimal Delamination, Casey Grey
Integrated Fiber Electrospinning: Creating Spatially Complex Electrospun Scaffolds With Minimal Delamination, Casey Grey
Theses and Dissertations
Tissue engineering scaffolds come in many shapes and sizes, however, due to difficulty manufacturing the microstructure architecture required in tissue engineering, most scaffolds are architecturally non-dynamic in nature. Because the microstructural architecture of all biological tissues is inherently complicated, non-dynamic tissue engineering scaffolds tend to be a poor platform for tissue regeneration. The current method for manufacturing dynamic tissue engineering scaffolds involves electrospinning successive layers of different fibers, an approach that exhibits no fiber transition between layers and subsequent delamination problems. In this study we aim to address the design challenges of tissue engineering scaffolds through our novel integrated fiber …
Modeling The Resistance To Hydrostatic Pressures For Superhydrophobic Coatings With Random Roughness, Thomas Michael Bucher Jr.
Modeling The Resistance To Hydrostatic Pressures For Superhydrophobic Coatings With Random Roughness, Thomas Michael Bucher Jr.
Theses and Dissertations
A superhydrophobic coating can be produced using a hydrophobic material textured with surface roughness on the micro-/nano-scale. Such a coating on the outside of a submersible body may result in reduced skin-friction drag due to a trapped layer of air in the coating. However, this layer may become unstable when subjected to elevated hydrostatic pressures, and a coating’s performance is compromised beyond a certain threshold (critical pressure). This thesis presents a numerical model for predicting the pressure tolerances of superhydrophobic coatings comprised of randomly deposited hydrophobic particles or fibers. We have also derived a set of force-balance-based analytical equations for …
Suspended Polypyrrole Films Supporting Alamethicin Reconstituted Bilayer Membranes, Robert Northcutt
Suspended Polypyrrole Films Supporting Alamethicin Reconstituted Bilayer Membranes, Robert Northcutt
Theses and Dissertations
This thesis presents a novel architecture for a sensing element fabricated from a conducting polymer and a bioderived membrane. The thin film device provides controlled, selective ion transport from a chemical concentration and produces measurable electrical signals, ion storage, and small scale actuation. A chemical gradient applied across a bioderived membrane generates ion flow through protein transporters in the presence of a gating signal. A conducting polymer undergoes ion ingress/egress in the presence of an electrical and chemical potential, which causes a change on the polymers conformal backbone. A ligand (or) voltage gated protein in the bioderived membrane results in …
Preparation And Characterization Of A Self-Crimp Side-By-Side Bicomponent Electrospun Material, Yang Han
Preparation And Characterization Of A Self-Crimp Side-By-Side Bicomponent Electrospun Material, Yang Han
Theses and Dissertations
Bicomponent composite fibers have been widely used in the textile industry and are gaining increasing attention on biomedical applications. In this research, polycaprolactone/poly (lactic acid) side-by-side bicomponent fibers were created for the application of a biodegradable scaffold. The side-by-side structure endowed the fiber with self-crimps when it was processed under certain conditions. This material was produced by electrospinning and collected on a high speed rotating mandrel to get highly oriented fibers. A mechanical stretch at the same direction was done followed by a wet heat treatment for polymer retraction. Crimped fibers were demonstrated by scanning electron microscopy. The quantitative porosity …
A Novel Method For Determining Acetabular Orientation, Sean Higgins
A Novel Method For Determining Acetabular Orientation, Sean Higgins
Theses and Dissertations
Enhanced knowledge of the acetabulum is of paramount importance in the diagnostic, planning, and execution stages of procedures and treatments targeting the hip joint. The convoluted and highly variable morphology of the structures comprising the bony pelvis make ascertaining measures of the acetabulum challenging. Furthermore, current methods for determining acetabular orientation assume symmetry between the separate halves of the pelvis by utilizing a coordinate system based on bilateral landmarks. The purpose of this study was to determine the three-dimensional orientation of the entire acetabulum. For this research, an improved programmatic method was developed for determining acetabular orientation using three-dimensional data. …
Mathematical Model And Experimental Exploration Of The Nanoinjector Lance Array, Nathan C. Toone
Mathematical Model And Experimental Exploration Of The Nanoinjector Lance Array, Nathan C. Toone
Theses and Dissertations
The Nanoinjector Lance Array has been developed to inject foreign material into thousands of cells at once using electrophoresis to attract and repel particles to and from the electrically-charged lances. A mathematical computer model simulating the motion of attracted or repelled proteins informs the design of the nanoinjection lance array system. The model is validated by accurately predicting protein velocity in electrophoresis experiments. A complete analysis of parameters is conducted via simulations and specific research questions regarding the counter electrode of the nanoinjector lance array system are explored using the model. A novel technique for fabricating lance arrays from collapsed …
Design And Testing Of A Biological Microelectromechanical System For The Injection Of Thousands Of Cells Simultaneously, Gregory Herlin Teichert
Design And Testing Of A Biological Microelectromechanical System For The Injection Of Thousands Of Cells Simultaneously, Gregory Herlin Teichert
Theses and Dissertations
The ability to inject DNA and other foreign particles into cells, both germ cells (e.g. to produce transgenic animals) and somatic cells (e.g. for gene therapy), is a powerful tool in genetic research. Nanoinjection is a method of DNA delivery that combines mechanical and electrical methods. It has proven to have higher cell viability than traditional microinjection, resulting in higher integration per injected embryo. The nanoinjection process can be performed on thousands of cells simultaneously using an array of microneedles that is inserted into a monolayer of cells. This thesis describes the needle array design requirements and the fabrication process …
The Effect Of A Navigational Aid On Training Of A Minimally Invasive Surgery Camera Task, Ketan Vidwans
The Effect Of A Navigational Aid On Training Of A Minimally Invasive Surgery Camera Task, Ketan Vidwans
Theses and Dissertations
Minimally Invasive Surgery (MIS) differs from Open Surgery as surgeons view the surgical site indirectly on a monitor. The view shown is typically from an angled endoscope off to one side of the surgery (i.e., uncollocated with the view of the hands). This makes camera navigation a challenging ability to learn. MIS thus requires longer training periods, more practice and mental effort to achieve proficiency. Current training setups and Operating Room (OR) environments lack appropriate real-time visual cues for navigation and other perception related information that could help with learning and performance in the OR. The purpose of this research …
Development Of Magnetic Fabrics With Tunable Hydrophobicity, Thu Ho
Development Of Magnetic Fabrics With Tunable Hydrophobicity, Thu Ho
Theses and Dissertations
Polystyrene (PS) fiber mats incorporating iron (Fe) particles were fabricated by electrospinning and the hydrophobicity of the resulting magnetic fabrics was investigated with and without an applied magnetic field. The results show that the hydrophobicity (as measured using water droplet contact angle) increases in the presence of a magnetic field and the hysterisis in the advancing/receding contact angle (a measure of the stickiness of the surface) decreases in the presence of a magnetic field. It is also shown that the contact angle and hysterises increase with decreasing fiber diameter and mat thickness.
Evaluation Of A Novel Myoelectric Training Device, Ryan Clingman
Evaluation Of A Novel Myoelectric Training Device, Ryan Clingman
Theses and Dissertations
While research shows that a patient’s success in using a myoelectric prosthetic arm is dependent on receiving effective training, current methods of training are not designed to effectively hold attention long enough for optimal training. This study focused on evaluating a novel myoelectric training device, consisting of a toy car controlled by EMG signals from the arm. Subjects’ performance with the trainer was evaluated to determine its ability to provide experience with EMG controls. Eight healthy adult subjects were taken through typical initial stages of myoelectric training, then asked to drive the car through a slalom course while the time, …
Efficiency Droop Mitigation And Quantum Efficiency Enhancement For Nitride Light-Emitting Diodes, Xing Li
Efficiency Droop Mitigation And Quantum Efficiency Enhancement For Nitride Light-Emitting Diodes, Xing Li
Theses and Dissertations
In the past decade, GaN-based nitrides have had a considerable impact in solid state lighting and high speed high power devices. InGaN-based LEDs have been widely used for all types of displays in TVs, computers, cell phones, etc. More and more high power LEDs have also been introduced in general lighting market. Once widely used, such LEDs could lead to the decrease of worldwide electrical consumption for lighting by more than 50% and reduce total electricity consumption by > 10%. However, there are still challenges for current state-of-the art InGaN-based LEDs, including ‘efficiency droop’ issues that cause output power quenching at …
Algan/Gan Dual Channel Hfets And Realization Of Gan Devices On Different Substrates, Mo Wu
Algan/Gan Dual Channel Hfets And Realization Of Gan Devices On Different Substrates, Mo Wu
Theses and Dissertations
GaN-based HFETs demonstrate ubiquitous high power and high frequency performance and attract tremendous research efforts. Even though significant advances have been achieved, there still exist some critical issues needed to be investigated and solved. In particular, high defect densities due to inhomogeneous growth and operation under high power conditions bring many unique problems which are not so critical in the conventional Si and GaAs materials systems. In order to reduce the defect density and heat dissipation of GaN-based HFETs, research work on the realization of GaN-based HFETs on bulk GaN substrate has been carried out and the key problems have …
The Biomechanical Implications Of An Intrinsic Decompressive Pre-Load On A Posterior Dynamic Stabilization System, Jeffrey Ellis Harris
The Biomechanical Implications Of An Intrinsic Decompressive Pre-Load On A Posterior Dynamic Stabilization System, Jeffrey Ellis Harris
Theses and Dissertations
The purpose of this research was to investigate the influence of applying an intrinsic decompressive pre-load to a particular dynamic stabilization device on the biomechanical response of the lumbar spine. The FlexSPAR, which supports this ability, was used as a test case. A finite element model of a full lumbar spine was developed and validated against experimental data, and tested in the primary modes of spinal motion. The model was used to compare five lumbar spine test cases: healthy, degenerate, implanted with a pre-loaded device, implanted with a device without a pre-load, and implanted with rigid fixators. Results indicated that …
Hybrid Spintronics And Straintronics: An Ultra-Low-Energy Computing Paradigm, Kuntal Roy
Hybrid Spintronics And Straintronics: An Ultra-Low-Energy Computing Paradigm, Kuntal Roy
Theses and Dissertations
The primary obstacle to continued downscaling of charge-based electronic devices in accordance with Moore's law is the excessive energy dissipation that takes place in the device during switching of bits. Unlike charge-based devices, spin-based devices are switched by flipping spins without moving charge in space. Although some energy is still dissipated in flipping spins, it can be considerably less than the energy associated with current flow in charge-based devices. Unfortunately, this advantage will be squandered if the method adopted to switch the spin is so energy-inefficient that the energy dissipated in the switching circuit far exceeds the energy dissipated inside …
Life History Switch Point Plasticy In Response To Pond Drying Alyers Metamorph Allometry And Jumping Performance, Julie Charbonnier
Life History Switch Point Plasticy In Response To Pond Drying Alyers Metamorph Allometry And Jumping Performance, Julie Charbonnier
Theses and Dissertations
Animals with complex life cycles can cope with environmental uncertainty by altering life history switch points through developmental plasticity. Pond drying is an important factor which may alter life history switch points in aquatic organisms. Many amphibians can plastically respond to changes in pond drying by emerging earlier, but few studies have examined the post-metamorphic consequences for performance. To investigate the potential carry-over effects of plasticity to pond drying, we studied the túngara frog, Physalaemus pustulosus, a tropical anuran that breeds in highly ephemeral habitats. We conducted a field study with three different water depth treatments in 60 L mesocosms …
Data Consistency And Conflict Avoidance In A Multi-User Cax Environment, Robert Aaron Moncur
Data Consistency And Conflict Avoidance In A Multi-User Cax Environment, Robert Aaron Moncur
Theses and Dissertations
This research presents a new method to preserve data consistency in a multi-user CAx environment. The new method includes three types of constraints which work by constraining and controlling both features and users across an entire multi-user CAx platform. The first type of constraint includes locking or reserving features to enable only one user at a time to edit a given feature. The second type of constraint, collaborative feature constraints, allows flexible constraining of each individual feature in a model, and the data that defines it. The third type of constraint, collaborative user constraints, allows the constraining of user permissions …
Multiple Fundamental Frequency Pitch Detection For Real Time Midi Applications, Nathan Hilbish
Multiple Fundamental Frequency Pitch Detection For Real Time Midi Applications, Nathan Hilbish
Theses and Dissertations
This study aimed to develop a real time multiple fundamental frequency detection algorithm for real time pitch to MIDI conversion applications. The algorithm described here uses neural network classifiers to make classifications in order to define a chord pattern (combination of multiple fundamental frequencies). The first classification uses a binary decision tree that determines the root note (first note) in a combination of notes; this is achieved through a neural network binary classifier. For each leaf of the binary tree, each classifier determines the frequency group of the root note (low or high frequency) until only two frequencies are left …
Design, Fabrication, And Testing Of Flexible Inkjet-Printed Antennas, Yahiea M. H. Al-Naiemy
Design, Fabrication, And Testing Of Flexible Inkjet-Printed Antennas, Yahiea M. H. Al-Naiemy
Theses and Dissertations
During the past four decades, microstrip antennas have attracted much attention due to their thin profile, ease of fabrication, low cost, and conformability. Inkjet-printing flexible antennas using highly conducting patterns can complement and extend the above-mentioned advantages to achieve modern, clean, fast, and reliable antenna fabrication technologies. Moreover, the use of nanoscale materials allows for the development of a new generation of modern printed circuit antennas. In this thesis, several microstrip antennas are presented with different geometries on both rigid and flexible substrates. The antennas were designed and simulated using two different 3D full-wave electromagnetic simulation tools: Ansoft's High Frequency …
Homogeneous Viologens For Use As Catalysts In Direct Carbohydrate Fuel Cells, Dane C. Hansen
Homogeneous Viologens For Use As Catalysts In Direct Carbohydrate Fuel Cells, Dane C. Hansen
Theses and Dissertations
Deriving electrical energy from glucose and other carbohydrates under mild conditions is an important research objective because these biomolecules are abundant, renewable, and can provide 12 to 24 electrons per molecule, yielding substantial electrical power. It was previously observed that disubstituted viologens, salts of N,N'-disubstituted 4,4'-bipyridine, are able to oxidize glucose under alkaline conditions. Building on that initial result, the objective of this work was to understand and quantify the effectiveness and utility of viologens as catalysts for use in direct carbohydrate fuel cells.The extent that viologens oxidize carbohydrates, the conditions under which that oxidation occurs, and the mechanism for …
Buckling And Crippling Of Square Steel Thin-Walled Tubes Fabricated With Symmetrically-Overlapping U-Channels And Foam, David Camenish Gelder
Buckling And Crippling Of Square Steel Thin-Walled Tubes Fabricated With Symmetrically-Overlapping U-Channels And Foam, David Camenish Gelder
Theses and Dissertations
Testing and analysis has been performed on square steel thin-walled tubes fabricated using symmetrically-overlapping U-channels and foam. This research analyzes flange-to-flange attachment, effect of foam in the columns, effect of adhesive stiffness, and influence of steel thickness, as related to the local buckling loads, global buckling loads, and crippling loads. Four 14-foot (4.27 m) foam-filled, thin-walled, galvanized steel columns were manufactured by Novatek, Inc. and tested in axial compression with pinned boundary conditions. For three of the four configurations, the two-piece 4-in. (10.2-cm) square shell surrounded prefabricated polystyrene foam inserts; the fourth column had no foam insert. The column outer …