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Articles 91 - 106 of 106
Full-Text Articles in Engineering
A High-Resolution Microscopic Electrical Impedance Imaging Modality: Scanning Impedance Imaging, Hongze Liu
A High-Resolution Microscopic Electrical Impedance Imaging Modality: Scanning Impedance Imaging, Hongze Liu
Theses and Dissertations
Electrical impedance imaging is an imaging technique which has the capability of revealing the spatial distribution of the electrical impedance inside biological tissues. Classical electrical impedance imaging including Electrical Impedance Tomography (EIT) typically has low resolution. Advances in electrical impedance imaging typically involve methods that either increase image resolution or image contrast. This study investigates the possibility of the resolution improvement for electrical impedance imaging using motion, and presents a novel high-resolution and calibrated impedance imaging method called Scanning electrical Impedance Imaging (SII). SII uses an electrical probe held at a known voltage and scanned over a thin sample immersed …
Culvert Hydraulics: Comparison Of Current Computer Models, Elizabeth Anne Thiele
Culvert Hydraulics: Comparison Of Current Computer Models, Elizabeth Anne Thiele
Theses and Dissertations
The hydraulic analysis of culverts is complicated when using hand calculations. Fortunately, several computer programs are available to assist in analyzing culvert hydraulics, some of which include HY-8, Fish X-ing, Broken-back Culvert Analysis Program (BCAP), Hydraflow Express, Culvert Master, Culvert, and Hydrologic Engineering Center River Analysis System (HEC-RAS). While all of these programs can simulate the behavior of flow through a culvert, slightly different methodologies are utilized among the programs to complete a full hydraulic analysis, resulting in different predictions for headwater depth, flow control, and outlet velocities. The purpose of this paper is to compare (1) the available hydraulic …
Spot Friction Welding Of Ultra High-Strength Automotive Sheet Steel, Jack H. Sederstrom
Spot Friction Welding Of Ultra High-Strength Automotive Sheet Steel, Jack H. Sederstrom
Theses and Dissertations
Spot friction welding (SFW) was performed on ultra high strength steel (UHSS) steel sheet commonly used in automobile manufacturing. Alloys studied included DP780, DP780EG, DP980, and DF140T sheet steel of varying thickness from 1.2 mm to 1.4 mm. Welding was accomplished using a PCBN standard tool. Weld strengths were then compared to a proposed AWS standard. Initial hardness readings were taken in cross sectioned samples. Grain structure in a SFW is presented. Resistance spot welds were created in three steels. This study focuses on the strength of SFW joints as compared to traditional resistance spot welding (RSW) in welding like …
Development Of An Efficient Solar Powered Unmanned Aerial Vehicle With An Onboard Solar Tracker, Troy Dixon Tegeder
Development Of An Efficient Solar Powered Unmanned Aerial Vehicle With An Onboard Solar Tracker, Troy Dixon Tegeder
Theses and Dissertations
Methods were developed for the design of a solar powered UAV capable of tracking the sun to achieve maximum solar energy capture. A single-axis solar tracking system was designed and constructed. This system autonomously rotated an onboard solar panel to find the angle of maximum solar irradiance while the UAV was airborne. A microcontroller was programmed and implemented to control the solar tracking system. A solar panel and an efficient airframe capable of housing the solar tracking system was designed and constructed. Each of these subsystems was tested individually with either ground or flight tests. Ultimately, the final assembled system …
Circuit And Modeling Solutions For High-Speed Chip-To-Chip Communication, Timothy Mowry Hollis
Circuit And Modeling Solutions For High-Speed Chip-To-Chip Communication, Timothy Mowry Hollis
Theses and Dissertations
This dissertation presents methods for modeling and mitigating voltage noise and timing jitter across high-speed chip-to-chip interconnects. Channel equalization and associated tuning schemes have been developed to target the distinct characteristics and signal degradation exhibited in the clock and data signals of multi-Gigabit/second digital communication links. Multiple methods for generating realistically degraded signals for the purpose of simulation are also presented and used to verify the proposed equalization and filtering topologies. Specifically, a new technique for modeling high-speed jittery clocks in the frequency domain is presented and shown to reduce transient simulation time and memory requirements, while simultaneously improving the …
Evaluating The Application Of Modularity To Reduce Market Risk In Technology Push Products, Aaron John Hopkinson
Evaluating The Application Of Modularity To Reduce Market Risk In Technology Push Products, Aaron John Hopkinson
Theses and Dissertations
Technology push product development presents a number of challenges over the more typical market pull product development. Despite these challenges, enough advantages exist to motivate firms to develop technology push products at greater risk. Modularity is a tool that can address some of these challenges. Currently most research and application of modularity have focused on market pull product development efforts. The research in this thesis explores the value of modularity in technology push product development through the development of methods and the analysis of 68 example products including 35 technology push products. A method has been developed for quantifying the …
One-Dimensional Performance Modeling Of Centrifugal Flow Vaned Diffusers, Jamin J. Bitter
One-Dimensional Performance Modeling Of Centrifugal Flow Vaned Diffusers, Jamin J. Bitter
Theses and Dissertations
The Two Element in Series (TEIS) and Two Zone models stand out as powerful tools that enable deeper understanding of compressor stage designs after they have been tested. The insights gained from these investigations have aided in improving new stage designs. Up to now, it has only been possible to use the TEIS and Two Zone models for analysis of test data due to the inability to predict the four required input parameters for untested machines. Empirical models for the TEIS and Two Zone model input parameters, ETAa5, ETAb5, Chi5, and DELTA5p, for two different types of vaned diffusers, channel …
Reducing Power In Fpga Designs Through Glitch Reduction, Nathaniel Hatley Rollins
Reducing Power In Fpga Designs Through Glitch Reduction, Nathaniel Hatley Rollins
Theses and Dissertations
While FPGAs provide flexibility for performing high performance DSP functions, they consume a significant amount of power. Often, a large portion of the dynamic power is wasted on unproductive signal glitches. Reducing glitching reduces dynamic energy consumption. In this study, retiming is used to reduce the unproductive energy wasted in signal glitches. Retiming can reduce energy by up to 92%. Evaluating energy consumption is an important part of energy reduction. In this work, an activity rate-based power estimation tool is introduced to provide FPGA architecture independent energy estimations at the gate level. This tool can accurately estimate power consumption to …
Accurate Target Geolocation And Vision-Based Landing With Application To Search And Engage Missions For Miniature Air Vehicles, Duncan B. Barber
Accurate Target Geolocation And Vision-Based Landing With Application To Search And Engage Missions For Miniature Air Vehicles, Duncan B. Barber
Theses and Dissertations
Miniature air vehicles (MAVs) have attracted a large amount of interest recently both from the research community and from the public. New battery technologies as well as rapid developments in embedded processing and MEMS sensor technologies have greatly increased the potential of these vehicles. MAVs have been envisioned playing significant roles in both civil and military applications. Examples include: fire monitoring, search and rescue, traffic monitoring, crop monitoring, convoy protection, border surveillance, troop support, law enforcement, natural disaster relief, and aerial photography. The application of MAVs tends to center on the ability of the MAV to collect and deliver visual …
Tessellated Surface Machining, Jiewu Lu
Tessellated Surface Machining, Jiewu Lu
Theses and Dissertations
Sculptured surface machining (SSM) is the end milling of sculptured surfaces with multi-axis machine tools. SSM consists of the tessellated model machining (TMM) and the parametric model machining (PMM). The former is gaining more and more attention over the past decade because it offers many advantages over the latter. New methods for various machining stages of TMM are proposed in this dissertation. First, in the 5-axis finish machining stage, a 3-dimension Configuration-space (3D C-space) machining method is presented. Next, in clean-up machining stage, an effective and creative approach is introduced. Finally, a complete TMM system is developed. The TMM system …
High Gain Low Power Operational Amplifier Design And Compensation Techniques, Lisha Li
High Gain Low Power Operational Amplifier Design And Compensation Techniques, Lisha Li
Theses and Dissertations
This dissertation discusses and compares the existing compensation methods for operational amplifiers. It explores a method to stabilize the op amps without sacrificing bandwidth to the same degree that commonly used methods do. A creative design methodology combining intuition, mathematical analysis, and mixed level simulation is explored for the new compensation scheme. The mixed level approach, associating system level simulation for most circuits along with device level simulation for some critical analog circuit paths, is presented to verify the behavior of new design concepts in an effective way. This approach also provides sufficient accuracy to predict the circuit performance realistically. …
Effect Of Initial Surface Treatment Timing On Chloride Concentrations In Concrete Bridge Decks, Aimee Worthen Birdsall
Effect Of Initial Surface Treatment Timing On Chloride Concentrations In Concrete Bridge Decks, Aimee Worthen Birdsall
Theses and Dissertations
Bridge engineers and managers in coastal areas and cold regions frequently specify the application of surface treatments on concrete bridge decks as barriers against chloride ingress. In consideration of concrete cover thickness and the presence of stay-in-place metal forms (SIPMFs), the objective of this research was to determine the latest timing of initial surface treatment applications on concrete bridge decks subjected to external chloride loading before chlorides accumulate in sufficient quantities to initiate corrosion during the service life of the deck. Chloride concentration data for this research were collected from 12 concrete bridge decks located within the I-215 corridor in …
An Investigation Of Methods To Homogeneously Entrain And Suspend Abrasive Particles In A Low Pressure Dental Water Jet, Michael Sean Grygla
An Investigation Of Methods To Homogeneously Entrain And Suspend Abrasive Particles In A Low Pressure Dental Water Jet, Michael Sean Grygla
Theses and Dissertations
During the past several decades, the water jet cutting concept has developed from a novel concept into a well-accepted machine cutting tool. With the addition of abrasive particles and the improvement of high pressure pumps, the water jet stream is currently capable of cutting through metal, concrete, and composite materials. Water jet systems have been utilized at a wide range of different pressures. Research performed at Brigham Young University has revealed that low pressure water jets have the ability to cut human teeth. Experiments have shown that when abrasive particles are added to the water jet stream, an greater amount …
An Improved Model For Calculating Heats Of Dilution And Equilibrium Constants For High Temperature Aqueous Electrolyte Solutions, Xiaoyun Lin
Theses and Dissertations
At high temperatures, the properties of aqueous electrolyte systems differ markedly from those at 25°C. For mixed-electrolyte dilute solutions at high temperatures, the degree of ion-association is sufficiently large that the association equilibrium must be incorporated in any model describing the solutions. These association reactions usually do not occur to a measurable extent at room temperature. Oscarson and co-workers have designed a correlation model based on the excess Gibbs energy which can correlate log K and ∆H values as well as the heats of dilution for aqueous electrolyte systems as a function of temperature (T) and ionic strength (I) from …
High-Frequency Ultrasound Drug Delivery And Cavitation, Mario Alfonso Diaz
High-Frequency Ultrasound Drug Delivery And Cavitation, Mario Alfonso Diaz
Theses and Dissertations
The viability of a drug delivery system which encapsulates chemotherapeutic drugs (Doxorubicin) in the hydrophobic core of polymeric micelles and triggers release by ultrasound application was investigated at an applied frequency of 500 kHz. The investigation also included elucidating the mechanism of drug release at 70 kHz, a frequency which had previously been shown to induce drug release. A fluorescence detection chamber was used to measure in vitro drug release from both Pluronic and stabilized micelles and a hydrophone was used to monitor bubble activity during the experiments. A threshold for release between 0.35 and 0.40 in mechanical index was …
A Numerical Vortex Approach To Aerodynamic Modeling Of Suav/Vtol Aircraft, Douglas F. Hunsaker
A Numerical Vortex Approach To Aerodynamic Modeling Of Suav/Vtol Aircraft, Douglas F. Hunsaker
Theses and Dissertations
A combined wing and propeller model is presented as a low-cost approach to preliminary modeling of slipstream effects on a finite wing. The wing aerodynamic model employs a numerical lifting-line method utilizing the 3D vortex lifting law along with known 2D airfoil data to predict the lift distribution across a wing for a prescribed upstream flowfield. The propeller/slipstream model uses blade element theory combined with momentum conservation equations. This model is expected to be of significant importance in the design of tail-sitter vertical take-off and landing (VTOL) aircraft, where the propeller slipstream is the primary source of air flow past …