Engineering Commons^™

Interactive Visualization Of Information Hierarchies And Applications On The Web, Confesor Santiago Iii

Theses and Dissertations

The visualization of information hierarchies is concerned with the presentation of abstract hierarchical information about relationships between various entities. It has many applications in diverse domains such as software engineering, information systems, biology, and chemistry. Information hierarchies are typically modeled by an abstract tree, where vertices are entities and edges represent relationships between entities. The aim of visualizing tree drawings is to automatically produce drawings of trees which clearly reflect the relationships of the information hierarchy.

This thesis is primarily concerned with problems related to the automatic generation of area-efficient grid drawings of trees, interactively visualizing information hierarchies, and applying …

Optimization Of Optical Computed Tomography Techniques For The Synthesis Of Particle Aggregate Models, Patrick Anthony Giordano Jr.

Theses and Dissertations

The characterization of 3-D shapes of particles in geomaterial aggregate mixtures is important for understanding the micro-mechanics of granular materials. Also, numerical synthesis of 3-D particle shapes from their corresponding shape descriptors is required for developing discrete element models (DEMs) that can be used to predict particle contact-forces, and ultimately the shear strength of the aggregate mixture.

Previous work has shown that Fourier-based 3-D shape descriptors can be constructed for aggregate mixtures, using a statistical combination of 2-D projections. Furthermore, optical tomography methods using the Algebraic Reconstruction Technique (ART) algorithm has proved capable of synthesizing 3-D shapes from 2-D projections, …

High Quality Molecular Beam Epitaxy Growth And Characterization Of Lead Titanate Zirconate Based Complex-Oxides, Xing Gu

Theses and Dissertations

Research interest in complex oxides has resurged owing to progress in modern epitaxial techniques. Among such oxides, lead-titanate-based thin films such as PbTiO₃ (PTO) and Pb(Zr_xTi_1−x)O₃ (PZT) offer attractive advantages for a wide variety of applications. Moreover, integration between functional oxides with compound semiconductors has the potential to realize multi-functional devices which enjoy the properties from both groups of materials. Ferroelectric materials with a perovskite structure (ABO₃) and semiconductors such as GaN with a hexagonal structure, require a careful choice of a bridge layer and suitable epitaxial technique. Molecular beam epitaxy (MBE) …

Optimizing Wireless Network Throughput: Methods And Applications, Pengchang Zhan

Theses and Dissertations

Ever since Marconi succeeded in his first demonstration on the possibility to communicate over the air overseas about a century ago, wireless communications have experienced dramatic improvements. Today's world sees the penetration of wireless communications into human life almost everywhere, from a simple remote control for TV to a cellular phone. With a better understanding of the adverse nature of the wireless propagation channels, engineers have been able to invent various clever techniques, i.e. Multiple Input Multiple Output (MIMO) technology, spread spectrum communications, Orthogonal Frequency Division Multiplexing (OFDM) to name a few, to achieve fast and reliable communications over each …

Low-Altitude Road Following, Using Strap-Down Cameras On Miniature Aerial Vehicles, Joseph M. Egbert

Theses and Dissertations

Miniature air vehicles (MAVs) are particularly well suited for short-distance, over-the-horizon, low-altitude surveillance and reconnaissance tasks. New camera and battery technologies have greatly increased a MAVs potential for these tasks. This thesis focuses on aerial surveillance of borders and roads, where a strap-down camera is used in-the-loop to track a border or road pathway. It is assumed that quality tracking requires that the pathway always remain in the footprint of the camera. The objective of this thesis is to explore roll-angle and altitude-above-ground-level constraints imposed on a bank-to-turn MAV due to the requirement to keep the pathway in the footprint …

Synthesis Of Optimal Arrays For Mimo And Diversity Systems, Britton T. Quist

Theses and Dissertations

This thesis proposes a method for determining the optimal antenna element radiation characteristics which maximize diversity gain given a specific power angular spectrum of the propagation environment. The method numerically constructs the eigenfunctions of the covariance operator for the scenario subject to constraints on the power radiated by each antenna as well as the level of supergain allowed in the solution. The optimal antenna characteristics are produced in terms of radiating current distributions along with their resulting radiation patterns. The results reveal that the optimal antennas can provide significantly more diversity gain than that provided by a simple practical design. …

Space-Time Coding With Offset Modulations, N. Thomas Nelson

Theses and Dissertations

In this dissertation it is shown that the telemetry versions of Feher-patented QPSK (FQPSK-JR) and shaped offset QPSK (SOQPSK-TG) can be interpreted as both cross-correlated, trellis-coded quadrature modulation (XTCQM) and continuous phase modulation (CPM). Based on these representations, both modulations can be detected with near optimal bit error rate performance using a common detector that is formulated as either an XTCQM detector, a traditional CPM detector, or a pulse amplitude modulation (PAM) detector (due to the PAM decomposition of the CPM representations of these modulations). In addition it is shown that the complexity of the XTCQM detector for SOQPSK-TG can …

Low Loss Hybrid Waveguide Electric Field Sensor Based On Optical D-Fiber, Eric K. Johnson

Theses and Dissertations

This thesis presents the fabrication of a low loss hybrid waveguide electric field(E-field) sensor based on optical D-fiber. This novel E-field sensor is formed as part of a contiguous fiber resulting in a flexible and small cross-section device that can be embedded into electronic circuitry. The in-fiber nature of this sensor also eliminates the need for alignment and packaging that conventional sensors need. An optical fiber can detect electric fields when the core of the fiber is partially removed and replaced with an electro-optic polymer. This polymer causes a change in the index of refraction in the waveguide of the …

Low-Voltage Analog Cmos Architectures And Design Methods, Kent Downing Layton

Theses and Dissertations

This dissertation develops design methods and architectures which allow analog circuits to operate at VT + 2Vds,sat, the minimum supply for CMOS circuits with all transistors in the active region where Vds,sat is the drain to source saturation voltage of a MOS transistor. Techniques which meet this criteria for rail-to-rail input stages, gain enhancement stages, and output stages are discussed and developed. These techniques are used to design four fully-differential rail-to-rail amplifiers. The highest gain is shown to be attained using a drain voltage equalization (DVE) or active-bootstrapping technique which produces more than 100dB of gain in a two stage …

Piezo-Electrochemical Transducer Effect (Pect) Intercalated Graphite Micro-Electromechanical Actuators, Glen A. Kading

Theses and Dissertations

The purpose of this research is to investigate the Piezo-Electrochemical Transducer (PECT) effect in intercalated graphite as a possible mechanism of actuation for micro-electromechanical systems (MEMS). This dissertation presents the results of research into the PECT effect in H2SO4-intercalated graphitized carbon fibers, including both electrical and mechanical characteristics of this effect. PECT fibers achieve up to 1.7% strain at 1.4 V of applied potential. In contrast, the piezoelectric material polyvinylidene difluoride (PVDF) generates only 0.01% strain and polysilicon thermal expansion between 0.02 and 0.06% strain depending on the thermal conductivity of the particular polysilicon that the actuators are fabricated in. …

Hybrid Micro-Electro-Mechanical Tunable Filter, Edward M. Ochoa

Theses and Dissertations

While advantages such as good thermal stability and processing-chemical compatibilities exist for common monolithic-integrated micro-electro-mechanically tunable filters (MEM-TF) and MEM-tunable vertical cavity surface emitting lasers (MT-VCSEL), they often require full processing to determine device characteristics. Alternatively, the MEM actuators and the optical parts may be fabricated separately, then subsequently bonded. This "hybrid approach" potentially increases design flexibility. Since hybrid techniques allow integration of heterogeneous material systems, "best of breed" compound optoelectronic devices may be customized to enable materials groups to be optimized for tasks they are best suited. Thus, as a first step toward a hybrid (Al_xGa_{1- …}

Polarimeter Blind Deconvolution Using Image Diversity, David M. Strong

Theses and Dissertations

This research presents an algorithm that improves the ability to view objects using an electro-optical imaging system with at least one polarization sensitive channel in addition to the primary channel. An innovative algorithm for detection and estimation of the defocus aberration present in an image is also developed. Using a known defocus aberration, an iterative polarimeter deconvolution algorithm is developed using a generalized expectation-maximization (GEM) model. The polarimeter deconvolution algorithm is extended to an iterative polarimeter multiframe blind deconvolution (PMFBD) algorithm with an unknown aberration. Using both simulated and laboratory images, the results of the new PMFBD algorithm clearly outperforms …

Energy-Efficient Querying Of Wireless Sensor Networks, Christopher R. Mann

Theses and Dissertations

Due to the distributed nature of information collection in wireless sensor networks and the inherent limitations of the component devices, the ability to store, locate, and retrieve data and services with minimum energy expenditure is a critical network function. Additionally, effective search protocols must scale efficiently and consume a minimum of network energy and memory reserves. A novel search protocol, the Trajectory-based Selective Broadcast Query protocol, is proposed. An analytical model of the protocol is derived, and an optimization model is formulated. Based on the results of analysis and simulation, the protocol is shown to reduce the expected total network …

Bipolar Cascade Vertical Cavity Surface Emitting Lasers For Rf Photonic Link Applications, William J. Siskaninetz

Theses and Dissertations

The development and demonstration of bipolar cascade vertical cavity surface emitting lasers is presented. The systematic approach to designing, fabricating, and characterizing the critical tunnel junction, incorporating the tunnel junction into an edge emitting bipolar cascade laser, and finally the transition to a VCSEL structure is detailed. A novel approach prior to growing and characterizing BC VCSELs was to investigate bipolar cascade light emitting diodes which incorporate the microcavity designs and disentangles the VCSEL cavity effects from the microcavity. The best performing p-doped oxide aperture microcavity design was then used as the microcavity for 1-, 2-, and 3-stage BC …

The Effects Of Signal And Image Compression Of Sar Data On Change Detection Algorithms, Kiran Shenoy

Theses and Dissertations

With massive amounts of SAR imagery and data being collected, the need for effective compression techniques is growing. One of the most popular applications for remote sensing is change detection, which compares two geo-registered images for changes in the scene. While lossless compression is needed for signal compression, the same is not often required for image compression. In almost every case the compression ratios are much higher in lossy compression making them more appealing when bandwidth and storage becomes an issue. This research analyzes different types of compression techniques that are adapted for SAR imagery, and tests these techniques with …

Navigation Using Orthogonal Frequency Division Multiplexed Signals Of Opportunity, Jamie S. Velotta

Theses and Dissertations

The global positioning system (GPS) provides high-accuracy position measurements anywhere in the world. However, a limitation of this system is that a line of sight to multiple satellites is required; therefore, it is unsuitable to use indoors or in urban canyons. Also, in the presence of radio-frequency interference or jamming, GPS may be unavailable. Alternative methods of navigation and positioning are need to either compliment GPS as a backup or for use in areas unreachable by satellites. This research analyzes a feature-based correlation approach for determining reception differences between two Orthogonal Frequency Division receivers for the purpose of TDOA calculations. …

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 …

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

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. …

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. …

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 …

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 …

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 …

Three Enabling Technologies For Vision-Based, Forest-Fire Perimeter Surveillance Using Multiple Unmanned Aerial Systems, Ryan S. Holt

Theses and Dissertations

The ability to gather and process information regarding the condition of forest fires is essential to cost-effective, safe, and efficient fire fighting. Advances in sensory and autopilot technology have made miniature unmanned aerial systems (UASs) an important tool in the acquisition of information. This thesis addresses some of the challenges faced when employing UASs for forest-fire perimeter surveillance; namely, perimeter tracking, cooperative perimeter surveillance, and path planning. Solutions to the first two issues are presented and a method for understanding path planning within the context of a forest-fire environment is demonstrated. Both simulation and hardware results are provided for each …

Performance Of Mimo Space-Time Coding Algorithms On A Parallel Dsp Test Platform, Beau C. Neal

Theses and Dissertations

Commercial Off The Shelf (COTS) hardware has the advantages of low cost, modularity, and is easily upgraded. For Multiple-Input Multiple-Output (MIMO) space-time algorithms to be practical they must have the processing capability to execute in real-time. This makes COTS ideal for real-time MIMO research where the processing power increases exponentially with a linear increase in antennas. The BYU Electrical Engineering wireless lab has designed and built an eight processor transmitter and a twenty processor receiver to research and develop MIMO wireless communication. The Alamouti, 2 x 2 and 4 x 4 differential space-time MIMO algorithms have been partially implemented on …

A Small-Scale 3d Imaging Platform For Algorithm Performance Evaluation, Steven A. James

Theses and Dissertations

In recent years, world events have expedited the need for the design and application of rapidly deployable airborne surveillance systems in urban environments. Fast and effective use of the surveillance images requires accurate modeling of the terrain being surveyed. The process of accurately modeling buildings, landmarks, or other items of interest on the surface of the earth, within a short lead time, has proven to be a challenging task. One approach of high importance for countering this challenge and accurately reconstructing 3D objects is through the employment of airborne 3D image acquisition platforms. While developments in this arena have significantly …

Controller Design For Accurate Antenna Pointing Onboard A Spacecraft, Victor M. Barba

Theses and Dissertations

Controller design for a spacecraft mounted flexible antenna is considered. The antenna plant model has a certain degree of uncertainty. Additionally, disturbances from the host spacecraft are transmitted to the antenna and need to be attenuated. The design concept explored herein entails feedforward control to slew the antenna. Feedback control is then used to compensate for plant uncertainty and to reject the disturbance signals. A tight control loop is designed to meet performance specifications while minimizing the control gains. Simulations are conducted to show that the integration of feedforward control action and feedback compensation produces better responses than the implementation …

Stacked Generalization For Early Diagnosis Of Alzheimer's Disease, Hardik P. Gandhi

Theses and Dissertations

Alzheimer's disease (AD) is a neurological disorder characterized by nerve degeneration and neuronal death. The diagnosis of AD at an early stage is a major concern due to growing number of elderly people affected by the disease, as well as the lack of a standard diagnosis procedure available to community clinics. A biomarker that will allow early diagnosis of the disease would be beneficial. Such biomarker should be noninvasive, simple to obtain, safe, inexpensive, accurate, and most importantly, must be made available to local health clinics for maximum effectiveness.

Recent studies have used wavelets and other signal processing methods to …

Finding Relevant Pdf Medical Journal Articles By The Content Of Their Figures As Well As Their Text, Ammon J. Christiansen

Theses and Dissertations

This work addresses the need for an alternative to keyword-based search for sifting through large PDF medical journal article document collections for literature review purposes. Despite users' best efforts to form precise and accurate queries, it is often difficult to guess the right keywords to find all the related articles while finding a minimum number of unrelated ones. Failure during literature review to find relevant, related research results in wasted research time and effort in addition to missing significant work in the related area which could affect the quality of the research work being conducted. The purpose of this work …

On-Chip Atomic Spectroscopy, Donald B. Conkey

Theses and Dissertations

This thesis presents the integration of atomic vapor cells with anti-resonant reflecting optical waveguides (ARROWs) fabricated on silicon chips. These potentially provide a compact platform for a number of optical applications, including the study of quantum coherence effects such as electromagnetically induced transparency and single-photon nonlinearities, as well as frequency stabilization standards. The use of hollow waveguides allows for light propagation in low index (vapor) media with compact mode areas. ARROWs make particularly attractive waveguides for this purpose because they can be interfaced with solid core waveguides, microfabricated on a planar substrate, and are effectively single mode. ARROW fabrication utilizes …