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Articles 1 - 30 of 34
Full-Text Articles in Engineering
Reliability Techniques For Data Communication And Storage In Fpga-Based Circuits, Yubo Li
Reliability Techniques For Data Communication And Storage In Fpga-Based Circuits, Yubo Li
Theses and Dissertations
This dissertation studies the effects of radiation-induced single-event upsets (SEUs) on field-programmable gate array(FPGA)-based circuits. It analyzes and quantifies a special case in data communication, that is, the synchronization issue of signals when they are sent across clock domains in triple modular redundancy (TMR) circuits with the presence of SEUs. After demonstrating that synchronizing errors cannot be eliminated in such case, this dissertation continues to present novel synchronizer designs that can guarantee reliable synchronization of triplicated signals. Fault injection tests then show that the proposed synchronizers provide between 6 and 10 orders of magnitude longer mean time to failure (MTTF) …
Efficient Estimation For Small Multi-Rotor Air Vehicles Operating In Unknown, Indoor Environments, John Charles Macdonald
Efficient Estimation For Small Multi-Rotor Air Vehicles Operating In Unknown, Indoor Environments, John Charles Macdonald
Theses and Dissertations
In this dissertation we present advances in developing an autonomous air vehicle capable of navigating through unknown, indoor environments. The problem imposes stringent limits on the computational power available onboard the vehicle, but the environment necessitates using 3D sensors such as stereo or RGB-D cameras whose data requires significant processing. We address the problem by proposing and developing key elements of a relative navigation scheme that moves as many processing tasks as possible out of the time-critical functions needed to maintain flight. We present in Chapter 2 analysis and results for an improved multirotor helicopter state estimator. The filter generates …
Dynamic Modeling, Trajectory Generation And Tracking For Towed Cable Systems, Liang Sun
Dynamic Modeling, Trajectory Generation And Tracking For Towed Cable Systems, Liang Sun
Theses and Dissertations
In this dissertation, we focus on the strategy that places and stabilizes the path of an aerial drogue, which is towed by a mothership aircraft using a long flexible cable, onto a horizontally flat orbit by maneuvering the mothership in the presence of wind. To achieve this goal, several studies for towed cable systems are conducted, which include the dynamic modeling for the cable, trajectory generation strategies for the mothership, trajectory-tracking control law design, and simulation and flight test implementations. First, a discretized approximation method based on finite element and lumped mass is employed to establish the mathematical model for …
Filtering Techniques For Pose Estimation With Applications To Unmanned Air Vehicles, Bryce Benson Ready
Filtering Techniques For Pose Estimation With Applications To Unmanned Air Vehicles, Bryce Benson Ready
Theses and Dissertations
This work presents two novel methods of estimating the state of a dynamic system in a Kalman Filtering framework. The first is an application specific method for use with systems performing Visual Odometry in a mostly planar scene. Because a Visual Odometry method inherently provides relative information about the pose of a platform, we use this system as part of the time update in a Kalman Filtering framework, and develop a novel way to propagate the uncertainty of the pose through this time update method. Our initial results show that this method is able to reduce localization error significantly with …
Fpga Floor-Planning Impact On Implementation Results, Jaren Tyler Lamprecht
Fpga Floor-Planning Impact On Implementation Results, Jaren Tyler Lamprecht
Theses and Dissertations
The field programmable gate array (FPGA) is an attractive computational platform for many applications because of its customizable nature and modest development cost, in terms of both time and money. As FPGAs scale to increased logical capacities, designers have increased flexibility. However, the FPGA placement problem becomes more difficult at increased sizes. Increasingly, designers are encouraged to structure designs hierarchically and floor-plan. Floor planning is a manual process which maps specified design submodules to selected physical regions of the FPGA device fabric. This thesis explores several of the effects that floor-planning has on submodules and the designs they comprise. A …
Developing A Guidance Law For A Small-Scale Controllable Projectile Using Backstepping And Adaptive Control Techniques And A Hardware System Implementation For A Uav And A Ugv To Track A Moving Ground Target, Kevin Christopher Meier
Developing A Guidance Law For A Small-Scale Controllable Projectile Using Backstepping And Adaptive Control Techniques And A Hardware System Implementation For A Uav And A Ugv To Track A Moving Ground Target, Kevin Christopher Meier
Theses and Dissertations
The work in this thesis is on two topics. The first topic focuses on collaboration between a UAV and a UGV to track a moving ground target. The second topic focuses on deriving a guidance law for a small-scale controllable projectile to be guided into a target. For the first topic, we implement a path planning algorithm in a hardware system for a UAV and UGV to track a ground target. The algorithm is designed for urban environments where it is common for objects to obstruct sensors located on the UAV and the UGV. During the hardware system's implementation, multiple …
Functionalization Of In-Plane Photonic Microcantilever Arrays For Biosensing Applications, Stanley J. Ness
Functionalization Of In-Plane Photonic Microcantilever Arrays For Biosensing Applications, Stanley J. Ness
Theses and Dissertations
Microcantilevers have been investigated as high sensitivity, label free biosensors for approximately 15 years. In nearly all cases, a thin gold film deposited on the microcantilevers is used as an intermediate attachment layer because of the convenience of thiol-gold chemistry. Unfortunately, this attachment chemistry can be unstable when used with complex sample media such as blood plasma. The Nordin group at BYU has recently developed an all-silicon in-plane photonic microcantilever (PMCL) technology to serve as a platform for label-free biosensing. It has the advantage of being readily scalable to simultaneous readout of many PMCLs in array format, and allows integration …
Application Of Seawinds Scatterometer Data To The Study Of Antarctic Icebergs, Keith Mitchell Stuart
Application Of Seawinds Scatterometer Data To The Study Of Antarctic Icebergs, Keith Mitchell Stuart
Theses and Dissertations
Knowledge of iceberg location and size is important for safety reasons as well as for understanding many geophysical and biological processes. This dissertation analyzes large tabular icebergs in the Southern Ocean using the SeaWinds scatterometer. SeaWinds is a spaceborne radar designed to measure the microwave backscatter from the Earth's surface. Using resolution-enhancement techniques, backscatter measurements are processed into backscatter images in which icebergs can be observed. An iceberg detection methodology is formalized using daily scatterometer images. Radar profiles from common Antarctic scatterers are quantified and an iceberg detection methodology is formalized using daily scatterometer images. Iceberg positions are determined in …
Technical Note On Manipulating Multivariate Gaussian Distributions, John C. Macdonald
Technical Note On Manipulating Multivariate Gaussian Distributions, John C. Macdonald
Student Works
In this technical note we present some derivations treating conditional, marginal, and joint distributions for Gaussian random vectors.
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 …
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 …
Design And Optimization Of A Miniature Radiation Pattern Reconfigurable Antenna For 2.4 Ghz Band And A Dual Tuned Birdcage Coil For Magnetic Resonance Imaging, Manoj Adhikari
Theses and Dissertations
This thesis describes development of a miniature reconfigurable antenna and optimization of a dual tuned birdcage coil. The design goals for the miniature reconfigurable antennas are resonance center frequency of 2.44 GHz, bandwidth of 2.4 GHz - 2.48 GHz, size of 0.8 cm x 1.2 cm, radiation efficiency of 70%, pattern correlation coefficient of 0.3 and input impedance of 50 Ω. The main goals to be achieved from the birdcage coil are the better homogeneity and higher signal to noise ratio than the existing coil. The design and optimization of both antenna and birdcage coil were done using simulation software …
Improved Methods For Phased Array Feed Beamforming In Single Dish Radio Astronomy, Michael James Elmer
Improved Methods For Phased Array Feed Beamforming In Single Dish Radio Astronomy, Michael James Elmer
Theses and Dissertations
Among the research topics needing to be addressed to further the development of phased array feeds (PAFs) for radio astronomical use are challenges associated with calibration, beamforming, and imaging for single dish observations. This dissertation addresses these concerns by providing analysis and solutions that provide a clearer understanding of the effort required to implement PAFs for complex scientific research. It is shown that calibration data are relatively stable over a period of five days and may still be adequate after 70 days. A calibration update system is presented with the potential to refresh old calibrators. Direction-dependent variations have a much …
Characterization And Preliminary Demonstration Of Microcantilever Array Integrated Sensors, Ryan R. Anderson
Characterization And Preliminary Demonstration Of Microcantilever Array Integrated Sensors, Ryan R. Anderson
Theses and Dissertations
I characterize the behavior of microcantilever arrays which utilize the in-plane photonic transduction that I've previously developed and evaluate the performance of the microcantilever arrays in simple sensing scenarios with integrated microfluidics. First the thermal responses of microcantilevers with a variety of patterns of deposited gold films are compared. Using a scanning electron microscope, I observe the deflection thermal sensitivities of 300 µm long microcantilevers to be -170.82 nm/K for a full gold coating and -1.93 nm/K for no gold coating. Using the photonic transduction method I measure a thermal sensitivity of -1.46 nm/K for a microcantilever array with no …
Liquid Dielectric Spectroscopy And Protein Simulation, Brett Lee Mellor
Liquid Dielectric Spectroscopy And Protein Simulation, Brett Lee Mellor
Theses and Dissertations
Protein electrical properties have been studied using dielectric relaxation measurements throughout the past century. These measurements have advanced both the theory and practice of liquid dielectric spectroscopy and have contributed to understanding of protein structure and function. In this dissertation, the relationship between permittivity measurements and underlying molecular mechanisms is explored. Also presented is a method to take molecular structures from the Protein Data Bank and subsequently estimate the charge distribution and dielectric relaxation properties of the proteins in solution. This process enables screening of target compounds for analysis by dielectric spectroscopy as well as better interpretation of protein relaxation …
Design And Polarimetric Calibration Of Dual-Polarized Phased Array Feeds For Radio Astronomy, Taylor D. Webb
Design And Polarimetric Calibration Of Dual-Polarized Phased Array Feeds For Radio Astronomy, Taylor D. Webb
Theses and Dissertations
Research institutions around the globe are developing phased array feed (PAF) systems for wide-field L-band radio astronomical observations. PAFs offer faster survey speeds and larger fields of view than standard single-pixel feeds, which enable rapid sky surveys and significantly increased scientific capability. Because deep space astronomical signals are inherently weak, PAF systems must meet stringent noise and sensitivity requirements. Meeting these requirements requires detailed modeling of the phased array itself as well as the reflector it is mounted on. This thesis details a novel approach to dual-pol PAF design that models the array and reflector as a complete system in …
Discrete-Time Implementation, Antenna Design, And Mimo For Near-Field Magnetic Induction Communications, Ronald Brett Gottula
Discrete-Time Implementation, Antenna Design, And Mimo For Near-Field Magnetic Induction Communications, Ronald Brett Gottula
Theses and Dissertations
Near-field magnetic induction (NFMI) is a short range wireless technology that uses loop antennas coupled by a magnetic field. NFMI antennas are electrically small and thus extremely inefficient and narrow band, making system design for multi-user and high-bitrate applications challenging. The goals of this thesis are to develop a test platform suitable for NFMI antenna testing, to model, design and test NFMI antennas that have high bandwidth-efficiency, and to explore the possibility of using MIMO (multiple-input multiple-output) to increase the capacity of the NFMI channel. This thesis provides system implementations, test results, and channel modeling to aid in the design …
Investigations Of The Dry Snow Zone Of The Greenland Ice Sheet Using Quikscat, Kevin Randall Moon
Investigations Of The Dry Snow Zone Of The Greenland Ice Sheet Using Quikscat, Kevin Randall Moon
Theses and Dissertations
The Greenland ice sheet is an area of great interest to the scientific community due to its role as an important bellwether for the global climate. Satellite-borne scatterometers are particularly well-suited to studying temporal changes in the Greenland ice sheet because of their high spatial coverage, frequent sampling, and sensitivity to the presence of liquid water. The dry snow zone is the largest component of the Greenland ice sheet and is identified as the region that experiences negligible annual melt. Due to the lack of melt in the dry snow zone, backscatter was previously assumed to be relatively constant over …
Automatic Discovery And Exposition Of Parallelism In Serial Applications For Compiler-Inserted Runtime Adaptation, David A. Greenland
Automatic Discovery And Exposition Of Parallelism In Serial Applications For Compiler-Inserted Runtime Adaptation, David A. Greenland
Theses and Dissertations
Compiler-Inserted Runtime Adaptation (CIRA) is a compilation and runtime adaptation strategy which has great potential for increasing performance in multicore systems. In this strategy, the compiler inserts directives into the application which will adapt the application at runtime. Its ability to overcome the obstacles of architectural and environmental diversity coupled with its flexibility to work with many programming languages and styles of applications make it a very powerful tool. However, it is not complete. In fact, there are many pieces still needed to accomplish these lofty goals. This work describes the automatic discovery of parallelism inherent in an application and …
Limited Resource Feature Detection, Description, And Matching, Spencer G. Fowers
Limited Resource Feature Detection, Description, And Matching, Spencer G. Fowers
Theses and Dissertations
The aims of this research work are to develop a feature detection, description, and matching system for low-resource applications. This work was motivated by the need for a vision sensor to assist the flight of a quad-rotor UAV. This application presented a real-world challenge of autonomous drift stabilization using vision sensors. The initial solution implemented a basic feature detector and matching system on an FPGA. The research then pursued ways to improve the vision system. Research began with color feature detection, and the Color Difference of Gaussians feature detector was developed. CDoG provides better results than gray scale DoG and …
Windowed Factorized Backprojection For Pulsed And Lfm-Cw Stripmap Sar, Kyra Michelle Moon
Windowed Factorized Backprojection For Pulsed And Lfm-Cw Stripmap Sar, Kyra Michelle Moon
Theses and Dissertations
Factorized backprojection is a processing algorithm for reconstructing images from data collected by synthetic aperture radar (SAR) systems. Factorized backprojection requires less computation than conventional time-domain backprojection with little loss in accuracy for straight-line motion. However, its implementation is not as straightforward as direct backprojection. Further, implementing an azimuth window has been difficult in previous versions of factorized backprojection. This thesis provides a new, easily parallelizable formulation of factorized backprojection designed for both pulsed and linearly frequency modulated continuous wave (LFM-CW) stripmap SAR data. A method of easily implementing an azimuth window as part of the factorized backprojection algorithm is …
Sea Ice Mapping Using Enhanced Resolution Advanced Scatterometer Images, Steven Joseph Reeves
Sea Ice Mapping Using Enhanced Resolution Advanced Scatterometer Images, Steven Joseph Reeves
Theses and Dissertations
Sea ice is of great interest due to its effect on the global climate, the Earth's ecosystem, and human activities. Microwave remote sensing has proven to be an effective way to measure many of the characteristics of sea ice. In particular, several algorithms map the daily sea ice extent using a variety of instruments. Enhanced resolution images generated from the Scatterometer Image Reconstruction (SIR) algorithm can be used to generate a high resolution ice extent map. Previous algorithms using SIR images were developed for scatterometers which are no longer operational. The Advanced Scatterometer (ASCAT) is a newer scatterometer which has …
Extending The Quikscat Data Record With The Oceansat-2 Scatterometer, Joshua P. Bradley
Extending The Quikscat Data Record With The Oceansat-2 Scatterometer, Joshua P. Bradley
Theses and Dissertations
Originally designed for wind velocity estimation over the ocean, scatterometers have since been applied to climate studies of the Earth's cryosphere and bioshere. As an integral part of climatological studies of the planet, the NASA Scatterometer Climate Record Pathfinder (SCP) supplies scatterometer-based products designed to aid researchers in climatological studies of the planet. In this thesis, necessary steps are taken to facilitate data from the Oceansat-2 Ku-band scatterometer (OSCAT) to be used in extending the Ku-band SCP dataset of conically scanning pencil-beam scatterometers begun by the Seawinds scatterometer flown on the QuikSCAT mission 1999-2009. As a standard SCP product, a …
Development Of L-Band Down Converter Boards And Real-Time Digital Backend For Phased Array Feeds, Vikas Asthana
Development Of L-Band Down Converter Boards And Real-Time Digital Backend For Phased Array Feeds, Vikas Asthana
Theses and Dissertations
Recent developments in the field of phased array feeds for radio astronomical reflector antennas, have opened a new frontier for array signal processing for radio astronomy observations. The goal is to replace single horn feeds with a phased array feed, so as to enable astronomers to cover more sky area in less time. The development of digital backend signal processing systems has been a major area of concentration for the development of science-ready phased array feeds for radio astronomers. This thesis focuses on the development of analog down-converter receivers and an FPGA-based digital backend for real-time data processing and analysis …
Electric Field Sensing In A Railgun Using Slab Coupled Optical Fiber Sensors, Jonathan Robert Noren
Electric Field Sensing In A Railgun Using Slab Coupled Optical Fiber Sensors, Jonathan Robert Noren
Theses and Dissertations
This thesis discusses the application of Slab Coupled Optical Fiber Sensors (SCOS) in a railgun. The specific goal of these sensors is to create an electric field profile at a specific point in the gun as the armature passes. The thesis explores the theory that powers the railgun as well as the principles of the SCOS sensors. It also elaborates on the various noise sources found throughout the detection system and concludes with a summary of the various field tests that were performed throughout this project. There are many benefits to using a railgun over traditional weapons in the field. …
Understanding Design Requirements For Building Reliable, Space-Based Fpga Mgt Systems Based On Radiation Test Results, Kevin M. Ellsworth
Understanding Design Requirements For Building Reliable, Space-Based Fpga Mgt Systems Based On Radiation Test Results, Kevin M. Ellsworth
Theses and Dissertations
Space-based computing applications often demand reliable, high-bandwidth communication systems. FPGAs with Mulit-Gigabit Transceivers (MGTs) provide an effective platform for such systems, but it is important that system designers understand the possible susceptibilities MGTs present to the system. Previous work has provided a foundation for understanding the susceptibility of raw FPGA MGTs but has fallen short of testing MGTs as part of a larger system. This work focuses on answering the questions MGT system designers need to know in order to build a reliable space-based MGT system. Two radiation tests were performed with a test architecture built on the Aurora protocol. …
Smart Phone-Based Indoor Guidance System For The Visually Impaired, Brandon Lee Taylor
Smart Phone-Based Indoor Guidance System For The Visually Impaired, Brandon Lee Taylor
Theses and Dissertations
A smart phone camera based indoor guidance system to aid the visually impaired is presented. Most proposed systems for aiding the visually impaired with indoor navigation are not feasible for widespread use due to cost, usability, or portability. We use a smart phone vision based system to create an indoor guidance system that is simple, accessible, inexpensive, and discrete to aid the visually impaired to navigate unfamiliar environments such as public buildings. The system consists of a smart phone and a server. The smart phone transmits pictures of the user's location to the server. The server processes the images and …
Mitigation Of Sea Ice Contamination In Quikscat Wind Retrieval, Weston Jay Hullinger
Mitigation Of Sea Ice Contamination In Quikscat Wind Retrieval, Weston Jay Hullinger
Theses and Dissertations
Satellite borne radar scatterometers provide frequent estimates of near surface wind vectors over the Earth's oceans. However in the polar oceans, the presence of sea ice in or near the measurement footprint can adversely a ect scatterometer measurements resulting in inaccurate wind estimates. Currently, such ice contamination is mitigated by discarding measurements within 50 km of detected sea ice. This approach is imperfect and causes loss of coverage. This thesis presents a new algorithm which detects ice-contaminated measurements based on a metric called the Ice Contribution Ratio (ICR) which measures the spatial ice contribution for each measurement. The ICR calculation …
Hardware And Software Fault-Tolerance Of Softcore Processors Implemented In Sram-Based Fpgas, Nathaniel Hatley Rollins
Hardware And Software Fault-Tolerance Of Softcore Processors Implemented In Sram-Based Fpgas, Nathaniel Hatley Rollins
Theses and Dissertations
Softcore processors are an attractive alternative to using expensive radiation-hardened processors for space-based applications. Since they can be implemented in the latest SRAM-based FPGA technologies, they are fast, flexible and significantly less expensive. However, unlike ASIC-based processors, the logic and routing of a softcore processor are vulnerable to the effects of single-event upsets (SEUs). To protect softcore processors from SEUs, this dissertation explores the processor design-space for the LEON3 softcore processor implemented in a commercial SRAM-based FPGA. The traditional mitigation techniques of triple modular redundancy (TMR) and duplication with compare (DWC) and checkpointing provide reliability to a softcore processor at …
Low-Photoluminescence Hollow Waveguide Platforms For High-Sensitivity Integrated Optical Sensors, Yue Zhao
Low-Photoluminescence Hollow Waveguide Platforms For High-Sensitivity Integrated Optical Sensors, Yue Zhao
Theses and Dissertations
This dissertation presents research on the fabrication of optofluidic sensor platforms, which consist of integrated hollow waveguides and solid waveguides. Antiresonant reflecting optical waveguides (ARROWs) filled with liquids or gases, can be used for high-sensitivity sensing in applications of biotechnology, chemical synthesis, and analytical chemistry. The fabrication method developed for integrated ARROW sensing platforms utilizes standard microfabrication processes and materials. Dielectric cladding layers are deposited on a silicon wafer using plasma-enhanced chemical vapor deposition (PECVD) or sputtering. A sacrificial material is then patterned over the bottom cladding layers by photolithography. Additional dielectric layers are deposited around the core, forming the …