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Articles 31 - 60 of 148
Full-Text Articles in Engineering
Two-Dimensional Modeling Of Ap/Htpb Utilizing A Vorticity Formulation And One-Dimensional Modeling Of Ap And Adn, Matthew L. Gross
Two-Dimensional Modeling Of Ap/Htpb Utilizing A Vorticity Formulation And One-Dimensional Modeling Of Ap And Adn, Matthew L. Gross
Theses and Dissertations
This document details original numerical studies performed by the author pertaining to the propellant oxidizer, ammonium perchlorate (AP). Detailed kinetic mechanisms have been utilized to model the combustion of the monopropellants AP and ADN, and a two-dimensional diffusion flame model has been developed to examine the flame structure above an AP/HTPB composite propellant. This work was part of an ongoing effort to develop theoretically based, a priori combustion models. The improved numerical model for AP combustion utilizes a “universal” gas-phase kinetic mechanism previously applied to combustion models of HMX, RDX, GAP, GAP/RDX, GAP/HMX, NG, BTTN, TMETN, GAP/BTTN, and GAP/RDX/BTTN. The …
High-Speed Data Acquisition And Fpga Detected Pulse Blanking System For Interference Mitigation In Radio Astronomy, Micah Alexander Lillrose
High-Speed Data Acquisition And Fpga Detected Pulse Blanking System For Interference Mitigation In Radio Astronomy, Micah Alexander Lillrose
Theses and Dissertations
Radio astronomy is the discipline dedicated to the study of celestial emissions in the radio band from a few MHz to 300 GHz. In recent years, spurious emissions from man-made devices that operate at these frequencies have made detection of astronomical signals difficult. These harmful RF transmissions are called radio frequency interference (RFI). One strategy to remove RFI is to apply spatial filtering using an array antenna. This thesis documents the development of a high-speed data acquisition system used to record data from 7- and 19-element phased array feeds. The system supports synchronous sampling over all channels and streams data …
Design And Fabrication Of Out-Of-Plane Silicon Microneedles With Integrated Hydrophobic Microchannels, Michael S. Diehl
Design And Fabrication Of Out-Of-Plane Silicon Microneedles With Integrated Hydrophobic Microchannels, Michael S. Diehl
Theses and Dissertations
Microfabricated needles have the potential for inexpensive drug delivery without pain. The ability to deliver medication painlessly to patients will someday be not just hoped for but expected by the general public. The commercialization of this technology will also lead to other valuable technologies, such as systems that continually monitor and control insulin or other drugs in diabetic patients. This research presents fabrication procedures developed to produce pyramidal-shaped microneedles with microchannels that will allow for fluid delivery. The microchannels are etched into the substrate surface of a [100] silicon wafer using inductively coupled plasma etching. After the channel etch a …
Experiments In Cooperative Timing For Miniature Air Vehicles, Derek R. Nelson, Timothy W. Mclain, Randal W. Beard
Experiments In Cooperative Timing For Miniature Air Vehicles, Derek R. Nelson, Timothy W. Mclain, Randal W. Beard
Faculty Publications
This paper presents experimental results for two cooperative timing missions carried out using a team of three miniature air vehicles (MAVs). Using a cooperative timing algorithm based on coordination functions and coordination variables, the MAV team executed a series of simultaneous arrival and cooperative fly-by missions. In the presence of significant wind disturbances, the average time difference between the first and last vehicle in the simultaneous arrival experiments was 1.6 s. For the cooperative fly-by experiments, the average timing error between vehicle arrivals was 0.6 s. These results demonstrate the practical feasibility of the cooperative timing approach.
Experiments In Cooperative Timing For Miniature Air Vehicles, Timothy Mclain, Derek R. Nelson, Randal W. Beard
Experiments In Cooperative Timing For Miniature Air Vehicles, Timothy Mclain, Derek R. Nelson, Randal W. Beard
Faculty Publications
This paper presents experimental results for two cooperative timing missions carried out using a team of three miniature air vehicles (MAVs). Using a cooperative timing algorithm based on coordination functions and coordination variables, the MAV team executed a series of simultaneous arrival and cooperative fly-by missions. In the presence of significant wind disturbances, the average time difference between the first and last vehicle in the simultaneous arrival experiments was 1.6 s. For the cooperative fly-by experiments, the average timing error between vehicle arrivals was 0.6 s. These results demonstrate the practical feasibility of the cooperative timing approach.
Obstacle Avoidance Using Circular Paths, Timothy Mclain, Randal W. Beard, Jeffery Brian Saunders
Obstacle Avoidance Using Circular Paths, Timothy Mclain, Randal W. Beard, Jeffery Brian Saunders
Faculty Publications
This paper develops a method of obstacle avoidance for fixed-wing miniature air vehicles (MAV) using a series of circular oscillating paths and a single point laser ranger. The laser ranger is a low power, light-weight device used to report the distance to an object in a single direction of the body frame of a MAV. The oscillating paths allow the laser ranger to scan for obstacles and possible escape paths for the MAV in the case of obstacle detection. The circular paths are generated along waypoint paths and transition between waypoint paths without loss of scanning capabilities. Obstacle avoidance is …
Decentralized Control Of Multiple Uavs For Perimeter And Target Surveillance, Derek B. Kingston
Decentralized Control Of Multiple Uavs For Perimeter And Target Surveillance, Derek B. Kingston
Theses and Dissertations
With the recent development of reliable autonomous technologies for small unmanned air vehicles (UAVs), the algorithms utilizing teams of these vehicles are becoming an increasingly important research area. Unfortunately, there is no unified framework into which all (or even most) cooperative control problems fall. Five factors that affect the development of cooperative control algorithms are objective coupling, communication, completeness, robustness, and efficiency. We classify cooperative control algorithms by these factors and then present three algorithms with application to target and perimeter surveillance and a method for decentralized algorithm design. The primary contributions of this research are the development and analysis …
Transitions Between Hover And Level Flight For A Tailsitter Uav, Stephen R. Osborne
Transitions Between Hover And Level Flight For A Tailsitter Uav, Stephen R. Osborne
Theses and Dissertations
Vertical Take-Off and Land (VTOL) Unmanned Air Vehicles (UAVs) possess several desirable characteristics, such as being able to hover and take-off or land in confined areas. One type of VTOL airframe, the tailsitter, has all of these advantages, as well as being able to fly in the more energy-efficient level flight mode. The tailsitter can track trajectories that successfully transition between hover and level flight modes. Three methods for performing transitions are described: a simple controller, a feedback linearization controller, and an adaptive controller. An autopilot navigational state machine with appropriate transitioning between level and hover waypoints is also presented. …
Development Of A Multiple Microphone Probe Calibrator, Jonathan Reed Oldham
Development Of A Multiple Microphone Probe Calibrator, Jonathan Reed Oldham
Theses and Dissertations
This paper presents the theory, design, and validation of a microphone calibrator used to calibrate multiple microphones simultaneously. This work was done in conjunction with the development of an acoustic energy density probe, which was used to validate the calibrator. The probe uses multiple microphones to acquire the data needed to compute the acoustic energy density. The probe microphones are 0.006 m diameter electret microphones which typically do not have an ideal “flat" response over a wide range of frequencies as compared to precision condenser microphones. The probe microphone characteristics prompted the need for simultaneous, multi-microphone magnitude calibration. The idea …
Elliptical Rolling Link Toggle Mechanisms For Passive Force Closures With Self-Adjustment, Jacob Ross Montierth
Elliptical Rolling Link Toggle Mechanisms For Passive Force Closures With Self-Adjustment, Jacob Ross Montierth
Theses and Dissertations
This thesis presents elliptical rolling contact joints as an alternative to circular rolling contact and conventional revolute joints where high quality force transmission "low friction and backlash" with variable output are desired. Parameters specific to the joint and its position are developed in terms of relative link angles and elliptical surface geometry. These parameters are used to generate the basic forward kinematics for elliptical rolling link toggle mechanisms with oscillatory motion and high mechanical advantage. As large compressive loads are characteristic of such mechanisms, stress conditions are identified and principles for joint stability with variable, precision outputs are discussed. Finally, …
Buckling-Restrained Braced Frame Connection Design And Testing, Bradly B. Coy
Buckling-Restrained Braced Frame Connection Design And Testing, Bradly B. Coy
Theses and Dissertations
As typically designed, the beam-column-brace connections of buckling-restrained braced steel frames have undesirable failure modes that compromise the integrity and performance of the frames and are costly to repair. To decrease the time and resources needed to repair the frames following an earthquake, a new connection design was developed that attempts to confine yielding to replaceable frame components. The design incorporates a gap in the beam beyond the edge of the beam-gusset weld that acts as a hinge and reduces moment forces transferred to the connection; it is bridged by splice plates that are bolted to the beam top flanges. …
Loading Rate Effects On Axial Pile Capacity In Clays, Michael Paul Garner
Loading Rate Effects On Axial Pile Capacity In Clays, Michael Paul Garner
Theses and Dissertations
In order to design more efficient and reliable structures, axial load tests are performed on foundation piles. Traditionally, static tests with an average duration of approximately twenty-four hours have been performed on test piles to obtain their axial capacity. These static tests require multiple piles used as anchors in addition to the test pile. Static tests are both expensive and time consuming. An alternative to static testing is dynamic testing which requires sophisticated interpretation, can damage the pile and may not produce accurate results. There is a relatively new testing method called the Statnamic Testing Method which tests foundation piles …
Dynamic Testing Of A Full-Scale Pile Cap With Dense Silty Sand Backfill, Todd J. Valentine
Dynamic Testing Of A Full-Scale Pile Cap With Dense Silty Sand Backfill, Todd J. Valentine
Theses and Dissertations
Full-scale dynamic lateral load tests were performed on a pile cap with a dense silty sand backfill condition. Two hydraulic load actuators connected a test pile cap with a reaction cap. The load actuators incrementally loaded the test cap up to 50 mm of displacement. After each load increment, the displacement was held constant while an eccentric mass shaker induced dynamic loads under a ramping sequence from 1 Hz to 10 Hz. A baseline response was developed under a no backfill condition. Passive soil pressure was measured using pressure cells and tactile sensors. It was concluded that the presence of …
Soft Surface Roll Mechanics Parameters For Light Vehicle Rollover Accident Reconstruction, Kevin Claude Henry
Soft Surface Roll Mechanics Parameters For Light Vehicle Rollover Accident Reconstruction, Kevin Claude Henry
Theses and Dissertations
Light vehicle rollover accidents on soft surfaces can be modeled assuming constant drag with linear motion equations and other engineering principles. The concept of using segment average results to evaluate roll mechanics parameters throughout a roll sequence, and specifically, segment duration to evaluate vehicle trajectory between ground impacts is developed. The trajectory model is presented, explained and compared to values obtained by analyzing digital video of rollover crash tests. Detailed film analysis procedures are developed to obtain data from rollover crash tests that are not otherwise documented. Elevation of the center of gravity of vehicles is obtained where instrumentation does …
Particle Filter Based Mosaicking For Forest Fire Tracking, Justin Mathew Bradley
Particle Filter Based Mosaicking For Forest Fire Tracking, Justin Mathew Bradley
Theses and Dissertations
Using autonomous miniature air vehicles (MAVs) is a cost-effective, simple method for collecting data about the size, shape, and location characteristics of a forest fire. However, noise in measurements used to compute pose (location and attitude) of the on-board camera leads to significant errors in the processing of collected video data. Typical methods using MAVs to track fires attempt to find single geolocation estimates and filter that estimate with subsequent observations. While this is an effective method of resolving the noise to achieve a better geolocation estimate, it reduces a fire to a single point or small set of points. …
Laterally Loaded Pile Cap Connections, Tony Eugene Stenlund
Laterally Loaded Pile Cap Connections, Tony Eugene Stenlund
Theses and Dissertations
There is presently considerable uncertainty regarding appropriate connection details between driven piles and pile caps. Prior research on the subject suggests that given a proper embedment length, a specialized reinforced connection may not be necessary. Eliminating these costly connection details could save thousands of dollars on both labor and materials. This research study focuses on the importance of the pile-to-cap connection detail with respect to the reinforcement connection and pile embedment length. Four pile caps were constructed, each with two 40 foot-long steel pipe piles, and were tested with different connection details. Two caps included a reinforced connection detail while …
A Geometry-Based Motion Planner For Direct Machining And Control, Robert M. Cheatham
A Geometry-Based Motion Planner For Direct Machining And Control, Robert M. Cheatham
Theses and Dissertations
Direct Machining And Control (DMAC) is a new method of controlling machine tools directly from process planning software. A motion planning module is developed for the DMAC system that operates directly off path geometry without pre-tessellation. The motion planner is developed with the intent to process Bezier curves. The motion planning module includes a deterministic predictor-corrector-type curve interpolator, a dynamics limiting module, and a two-pass jerk-limited speed profiling algorithm. The methods are verified by machining an automotive surface in a clay medium and evaluating the resultant machine dynamics, feed rate, and chordal error throughout the machining process.
Investigation Of Particle Velocity And Drag With Spherical And Non-Spherical Particles Through A Backward Facing Step, Kyle Frederick Larsen
Investigation Of Particle Velocity And Drag With Spherical And Non-Spherical Particles Through A Backward Facing Step, Kyle Frederick Larsen
Theses and Dissertations
Numerous practical applications exist where dispersed solid particles are transported within a turbulent accelerating or decelerating gaseous flow. The large density variation between phases creates the potential for significant differences in velocity known as velocity slip. Flow over a backward facing step provides a well characterized, turbulent, decelerating flow useful for measuring the relative velocities of the solid and gaseous phases in order to determine velocity slip and particle drag. Numerous investigations have been conducted to determine the gas phase velocity in a backward facing step for both laminar and turbulent flows and therefore the gas phase flow is well …
A Selective Approach To Hexahedral Refinement Of Unstructured Conformal Meshes, Michael Hubbard Parrish
A Selective Approach To Hexahedral Refinement Of Unstructured Conformal Meshes, Michael Hubbard Parrish
Theses and Dissertations
Hexahedral refinement increases the density of an all-hexahedral mesh in a specified region, improving numerical accuracy. Previous research using solely sheet refinement theory made the implementation computationally expensive and unable to effectively handle multiply-connected transition elements and self-intersecting hexahedral sheets. The Selective Approach method is a new procedure that combines two diverse methodologies to create an efficient and robust algorithm able to handle the above stated problems. These two refinement methods are: 1) element by element refinement and 2) directional refinement. In element by element refinement, the three inherent directions of a hexahedron are refined in one step using one …
A Safety Analysis Of Fatigue And Drowsy Driving In The State Of Utah, Hunter T. Young
A Safety Analysis Of Fatigue And Drowsy Driving In The State Of Utah, Hunter T. Young
Theses and Dissertations
Fatigue and drowsy driving in the state of Utah has been a causal factor in thousands of crashes over the years and poses a serious threat to public safety. Consequently, the purpose of this research was to evaluate the impact of drowsy driving in the state, to identify locations where fatigue and drowsy driving may be contributing factors to current crashes, and to identify methods to help mitigate these crashes. A 3-year drowsy driving crash rate spanning the years 2002 – 2004 was used to determine which segments of Utah highway are most prone to drowsy driving crashes. Drowsy driving …
A Wind And Rain Backscatter Model Derived From Amsr And Seawinds Data, Seth Niels Nielsen
A Wind And Rain Backscatter Model Derived From Amsr And Seawinds Data, Seth Niels Nielsen
Theses and Dissertations
The SeaWinds scatterometers aboard the QuikSCAT and ADEOS II satellites were originally designed to measure wind vectors over the ocean by exploiting the relationship between wind-induced surface roughening and the normalized radar backscatter cross-section. Recently, an algorithm for simultaneously retrieving wind and rain (SWR) from scatterometer measurements was developed that enables SeaWinds to correct rain-corrupted wind measurements and retrieve rain rate data. This algorithm is based on co-locating Tropical Rainfall Measuring Mission Precipitation Radar (TRMM PR) and SeaWinds on QuikSCAT data. In this thesis, a new wind and rain radar backscatter model is developed for the SWR algorithm using a …
Potential Energy Surfaces For Small Alcohol Dimers. Ii. Propanol, Isopropanol, T-Butanol, And Sec-Butanol, Richard L. Rowley, Christopher M. Tracy, Tapani A. Pakkanen
Potential Energy Surfaces For Small Alcohol Dimers. Ii. Propanol, Isopropanol, T-Butanol, And Sec-Butanol, Richard L. Rowley, Christopher M. Tracy, Tapani A. Pakkanen
Faculty Publications
Potential energy landscapes for homogeneous dimers of propanol, isopropanol, tert-butanol, and sec-butanol were obtained using 735 counterpoise-corrected energies at the MP2/6-311+G(2df,2pd) level. The landscapes were sampled at 15 dimer separation distances for different relative monomer geometries, or routes, given in terms of the yaw, pitch, and roll of one monomer relative to the other and the spherical angles between the two monomer centers (taken as the C atom attached to the O). The resultant individual energy surfaces and their complex topographies were also regressed using a site-site pair potential model using a modified Morse potential that provides a mathematically simple …
Autonomic Product Development Process Automation, John E. Daley
Autonomic Product Development Process Automation, John E. Daley
Theses and Dissertations
Market globalization and mass customization requirements are forcing companies towards automation of their product development processes. Many task-specific software solutions provide localized automation. Coordinating these local solutions to automate higher-level processes requires significant software maintenance costs due to the incompatibility of the software tools and the dynamic nature of the product development environment. Current automation methods do not provide the required level of flexibility to operate in this dynamic environment. An autonomic product development process automation strategy is proposed in order to provide a flexible, standardized approach to product development process automation and to significantly reduce the software maintenance costs …
Hardware Support For A Configurable Architecture For Real-Time Embedded Systems On A Programmable Chip, Spencer W. Isaacson
Hardware Support For A Configurable Architecture For Real-Time Embedded Systems On A Programmable Chip, Spencer W. Isaacson
Theses and Dissertations
Current FPGA technology has advanced to the point that useful embedded SoPCs can now be designed. The Real Time Processor (RTP) project at Brigham Young University leverages the advances in FPGA technology with a system architecture that is customizable to specific applications. A simple real-time processor has been designed to provide support for a hardware-assisted real-time operating system providing fast context switches. As part of the hardware RTOS, the following have been implemented in hardware: scheduler, register banks, mutex, semaphore, queue, interrupts, event, and others. A novel circuit called the Task-Resource Matrix has been created to allow fast inter/intra processor …
Comparing The Feasibility Of Cutting Thin-Walled Sections From Five Commonly Used Metals Utilizing Wire Electric Discharge Machining, Richard C. Stephenson
Comparing The Feasibility Of Cutting Thin-Walled Sections From Five Commonly Used Metals Utilizing Wire Electric Discharge Machining, Richard C. Stephenson
Theses and Dissertations
Wire Electric Discharge Machining (wire-EDM) is a non-traditional machining process. Controlled electric sparks are successively used to vaporize part of a workpiece along a programmed path in order to machine a desired part. Because there is no tool that comes in direct contact with the workpiece, it is possible to machine thin, delicate parts. This thesis was designed to observe and analyze the differences in cutting capabilities for a conventional wire-EDM machine when cutting thin-walled sections from five commonly used metals utilizing a variation of roughing and finishing passes. The five metals that were used in this study are: Aluminum …
Compilation And Generation Of Multi-Processor On A Chip Real-Time Embedded Systems, Randall S. Klingler
Compilation And Generation Of Multi-Processor On A Chip Real-Time Embedded Systems, Randall S. Klingler
Theses and Dissertations
Current FPGA technology has advanced to the point that useful embedded System-on-Programmable-Chips (SoPC)s can now be designed. The Real Time Processor (RTP) project leverages the advances in FPGA technology with a system architecture that is customizable to specific real-time applications. The design and implementation of the framework for architecting such a system from ANSI-C code is presented. The Small Device C Compiler (SDCC) was retargeted to the RTP architecture and extended to produce a generator directive file. The RTPGen hardware generator was created to consume the directive file and produce a highly customized top-level structural VHDL file that can be …
Bubble Dynamics Of Ultrasonic Drug Release From Polymeric Micelles, Mario A. Diaz, William G. Pitt
Bubble Dynamics Of Ultrasonic Drug Release From Polymeric Micelles, Mario A. Diaz, William G. Pitt
Faculty Publications
We have reported the ability of Pluronic P-105 micelles to sequester anthracycline drugs and release their contents upon application of 70 kHz ultrasound (US)1 (Figure 1). Optimal targeting to tumors depends on focus and control of US insonation, which is better achieved at higher frequencies. While no evidence of in vitro drug release was found at 500 kHz, drug release at 70 kHz correlates with the intensity of the subharmonic signal in the acoustic spectrum generated by the insonated bubbles2(Figure 2). Having established that bubble oscillations (cavitation) are directly related to drug release at 70 kHz, we now investigate the …
Ultrasonically-Assisted Drug Delivery In Rats Reduces Tumor Growth, William G. Pitt, Beverly L. Roeder, G. Bruce Schaalje, Bryant J. Staples
Ultrasonically-Assisted Drug Delivery In Rats Reduces Tumor Growth, William G. Pitt, Beverly L. Roeder, G. Bruce Schaalje, Bryant J. Staples
Faculty Publications
Previously we have shown that nanosized drug carriers called Plurogels™ sequestered Doxorubicin (Dox) and partially released this drug with application of ultrasound (US) (Fig. 1)1. The application to chemotherapy was successfully demonstrated in a rat tumor model2. However previous studies did not examine the distribution of Dox in the insonated and control tissue. This recent work investigated the effect of two US frequencies and examined the Dox distribution in the insonated and control tumors to determine if US was depositing more Dox at the insonated site.
Development Of Deployable Wings For Small Unmanned Aerial Vehicles Using Compliant Mechanisms, Steven D. Landon
Development Of Deployable Wings For Small Unmanned Aerial Vehicles Using Compliant Mechanisms, Steven D. Landon
Theses and Dissertations
Unmanned Air Vehicles (UAVs) have recently gained attention due to their increased ability to perform sophisticated missions with less cost and/or risk than their manned counterparts. This thesis develops approaches to the use of compliant mechanisms in the design of deployable wings for small UAVs. Although deployable wings with rigid-link mechanisms have been used in the past to maintain flight endurance while minimizing required storage volume, compliant mechanisms offer many advantages in manufacturability and potential space savings due to function sharing of components. A number of compliant, deployable wing concepts are generated and a classification system for them is formed. …
Friction Stir Welding Of High-Strength Automotive Steel, Eric Michael Olsen
Friction Stir Welding Of High-Strength Automotive Steel, Eric Michael Olsen
Theses and Dissertations
The following thesis is a study on the ability to create acceptable welds in thin-plate, ultra-high-strength steels (UHSS) by way of friction stir welding (FSW). Steels are welded together to create tailor-welded blanks (TWB) for use in the automotive industry. Dual Phase (DP) 590, 780, and 980 steel as well as Transformation-Induced Plasticity (TRIP) 590 steel with thicknesses ranging from 1.2 mm to 1.8 mm were welded using friction stir welding under a variety of processing conditions, including experiments with dissimilar thicknesses. Samples were tested under tensile loads for initial determination if an acceptable weld had been created. Acceptable welds …