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Articles 1 - 30 of 82
Full-Text Articles in Engineering
Decision-Based Data Fusion Of Complementary Features For The Early Diagnosis Of Alzheimer's Disease, Metin Ahiskali
Decision-Based Data Fusion Of Complementary Features For The Early Diagnosis Of Alzheimer's Disease, Metin Ahiskali
Theses and Dissertations
As the average life expectancy increases, particularly in developing countries, the prevalence of Alzheimer's disease (AD), which is the most common form of dementia worldwide, has increased dramatically. As there is no cure to stop or reverse the effects of AD, the early diagnosis and detection is of utmost concern. Recent pharmacological advances have shown the ability to slow the progression of AD; however, the efficacy of these treatments is dependent on the ability to detect the disease at the earliest stage possible. Many patients are limited to small community clinics, by geographic and/or financial constraints. Making diagnosis possible at …
Heat And Current Propagation In Buffered Superconducting And Hyper-Conducting Wire, Jesse L. Lynn
Heat And Current Propagation In Buffered Superconducting And Hyper-Conducting Wire, Jesse L. Lynn
Theses and Dissertations
This research models and analyzes the distribution of heat and current in a buffered superconducting or hyper-conducting wire that shows potential for use in different capacities in multiple Air Force systems including the Active Denial System. The thesis includes a brief background of the reaction-diffusion system of partial differential equations provided by AFRL/RZPG and development of the numerical scheme. It then explores solutions to the model. These solutions indicate some of the various heat-related failures that may be observed in such a wire. The nature of the solutions observed depends on the characteristics of the wire, operating temperature and efficiency …
Electromagnetic Field Control And Optimization Using Metamaterials, Jeffrey S. Mcguirk
Electromagnetic Field Control And Optimization Using Metamaterials, Jeffrey S. Mcguirk
Theses and Dissertations
Transformation optics has shown the ability to cloak an object from incident electromagnetic radiation is possible. However, the material parameters are inhomogeneous, anisotropic, and, in some instances, singular at various locations. In order for a cloak to be practically realized, simplified parameter sets are required. However, the simplified parameters result in a degradation in the cloaking function. Constitutive parameters for simplified two-dimensional cylindrical cloaks have been developed with two material property constraints. It was initially believed satisfying these two constraints would result in the simplified cylindrical cloaks having the same wave equation as an ideal cloak. Because of this error, …
A Physical Model Of Human Skin And Its Application For Search And Rescue, Abel S. Nunez
A Physical Model Of Human Skin And Its Application For Search And Rescue, Abel S. Nunez
Theses and Dissertations
For this research we created a human skin reflectance model in the VIS and NIR. We then modeled sensor output for an RGB sensor based on output from the skin reflectance model. The model was also used to create a skin detection algorithm and a skin pigmentation level (skin reflectance at 685nm) estimation algorithm. The average root mean square error across the VIS and NIR between the skin reflectance model and measured data was 2%. The skin reflectance model then allowed us to generate qualitatively accurate responses for an RGB sensor for different biological and lighting conditions. To test the …
Studies On The Performance And Impact Of Channel Estimation In Mimo And Ofdm Systems, Michael David Larsen
Studies On The Performance And Impact Of Channel Estimation In Mimo And Ofdm Systems, Michael David Larsen
Theses and Dissertations
The need for reliable, high-throughput, mobile wireless communication technologies has never been greater as increases in the demand for on-the-go access to information, entertainment, and other electronic services continues. Two such technologies, which are at the forefront of current research efforts, are orthogonal frequency division multiplexing (OFDM) and multiple-input multiple-output (MIMO) systems, their union being known simply as MIMO-OFDM. The successful performance of these technologies depends upon the availability of accurate information concerning the wireless communication channel. In this dissertation, several issues related to quality of this channel state information (CSI) are studied. Specifically, the first part of this dissertation …
Efficient Implementation Of Raid-6 Encoding And Decoding On A Field Programmable Gate Array (Fpga), David Jacob
Efficient Implementation Of Raid-6 Encoding And Decoding On A Field Programmable Gate Array (Fpga), David Jacob
Theses and Dissertations
RAID-6 is a data encoding scheme used to provide single drive error detection and dual drive error correction for data redundancy on an array of disks. Here we present a thorough study of efficient implementations of RAID-6 on field programmable gate arrays (FPGAs). Since RAID-6 relies heavily on Galois Field Algebra (GFA), an efficient implementation of a GFA FPGA library is also presented. Through rigorous performance analysis, this work shows the most efficient ways to tradeoff FPGA resources and execution time when implementing GFA functions as well as RAID-6 encoding and decoding.
In-Plane, All-Photonic Transduction Method For Silicon Photonic Microcantilever Array Sensors, Jong Wook Noh
In-Plane, All-Photonic Transduction Method For Silicon Photonic Microcantilever Array Sensors, Jong Wook Noh
Theses and Dissertations
We have invented an in-plane all-photonic transduction method for photonic microcantilever arrays that is scalable to large arrays for sensing applications in both bio- and nanotechnology. Our photonic transduction method utilizes a microcantilever forming a single mode rib waveguide and a differential splitter consisting of an asymmetric multimode waveguide and a Y-branch waveguide splitter. The differential splitter's outputs are used to form a differential signal that has a monotonic response to microcantilever deflection. A differential splitter using an amorphous silicon strip-loaded multimode rib waveguide is designed and fabricated to demonstrate the feasibility of the in-plane photonic transduction method. Our initial …
An Evaluation Of Quikscat Uhr Wind Product's Effectiveness In Determining Selected Tropical Cyclone Characteristics, Faozi Said
Theses and Dissertations
While the standard wind product (L2B) available operationally in near-real time from SeaWinds on QuikSCAT is only 25 km in resolution, QuikSCAT data can be enhanced to yield a 2.5 km ultra-high resolution (UHR) product. The latter can be used to help estimate Tropical Cyclone (TC) characteristics such as TC eye center and wind radii. Two studies are conducted in this thesis, in which QuikSCAT UHR wind product's effectiveness in estimating these TC characteristics is evaluated. First, a comparison is made between the analyst's choice of eye location based on UHR images and interpolated best-track position. In this analysis, the …
Gan Heterojunction Fet Device Fabrication, Characterization And Modeling, Qian Fan
Gan Heterojunction Fet Device Fabrication, Characterization And Modeling, Qian Fan
Theses and Dissertations
This dissertation is focused on the research efforts to develop the growth, processing, and modeling technologies for GaN-based Heterojunction Field Effect Transistors (HFETs). The interest in investigating GaN HFETs is motivated by the advantageous material properties of nitride semiconductor such as large band gap, large breakdown voltage, and high saturation velocity, which make it very promising for the high power and microwave applications. Although enormous progress has been made on GaN transistors in the past decades, the technologies for nitride transistors are still not mature, especially concerning the reliability and stability of the device. In order to improve the device …
Improving Accuracy In Microwave Radiometry Via Probability And Inverse Problem Theory, Derek Lavell Hudson
Improving Accuracy In Microwave Radiometry Via Probability And Inverse Problem Theory, Derek Lavell Hudson
Theses and Dissertations
Three problems at the forefront of microwave radiometry are solved using probability theory and inverse problem formulations which are heavily based in probability theory. Probability theory is able to capture information about random phenomena, while inverse problem theory processes that information. The use of these theories results in more accurate estimates and assessments of estimate error than is possible with previous, non-probabilistic approaches. The benefits of probabilistic approaches are expounded and demonstrated. The first problem to be solved is a derivation of the error that remains after using a method which corrects radiometric measurements for polarization rotation. Yueh [1] proposed …
Slab-Coupled Optical Fiber Sensors For Electric Field Sensing Applications, Richard S. Gibson
Slab-Coupled Optical Fiber Sensors For Electric Field Sensing Applications, Richard S. Gibson
Theses and Dissertations
This dissertation presents the creation of slab coupled optical sensors (SCOS) for electric field sensing applications. SCOS devices utilize the benefits of an optical fiber system for high bandwidth and low electromagnetic interference. These sensors are fabricated by means of mode coupling between a small section of D-shaped optical fiber (D-fiber) with a multi-mode electro-optic slab waveguide. Electric field detection is accomplished by monitoring the behavior of the resonances, seen as transmission dips in the D-fiber transmission, as they shift with electric fields. The novelties of SCOS devices include their small compact nature, potential for sensor multiplexing and a dielectric …
Low Cost/ High Precision Flight Dynamics Estimation Using The Square-Root Unscented Kalman Filter, Trevor H. Paulsen
Low Cost/ High Precision Flight Dynamics Estimation Using The Square-Root Unscented Kalman Filter, Trevor H. Paulsen
Theses and Dissertations
For over a decade, Brigham Young University's Microwave Earth Remote Sensing (MERS) team has been developing SAR systems and SAR processing algorithms. In order to create the most accurate image reconstruction algorithms, detailed aircraft motion data is essential. In 2008, the MERS team purchased a costly inertial measurement unit (IMU) coupled with a high precision global positioning system (GPS) from NovAtel, Inc. In order to lower the cost of obtaining detailed motion measurements, the MERS group decided to build a system that mimics the capability the NovAtel system as closely as possible for a much lower cost. As a first …
Electronic Image Stabilization For Mobile Robotic Vision Systems, Michael John Smith
Electronic Image Stabilization For Mobile Robotic Vision Systems, Michael John Smith
Theses and Dissertations
When a camera is affixed on a dynamic mobile robot, image stabilization is the first step towards more complex analysis on the video feed. This thesis presents a novel electronic image stabilization (EIS) algorithm for small inexpensive highly dynamic mobile robotic platforms with onboard camera systems. The algorithm combines optical flow motion parameter estimation with angular rate data provided by a strapdown inertial measurement unit (IMU). A discrete Kalman filter in feedforward configuration is used for optimal fusion of the two data sources. Performance evaluations are conducted by a simulated video truth model (capturing the effects of image translation, rotation, …
The Navigation Potential Of Ground Feature Tracking, Guner Mutlu
The Navigation Potential Of Ground Feature Tracking, Guner Mutlu
Theses and Dissertations
This research effort examines the reduction of error in inertial navigation aided by vision. This is part of an effort focused on navigation in a GPS denied environment. The navigation concept examined here consists of two main steps. First, extract the position of a tracked ground object using vision and geo-locate it in 3 dimensional navigation frame. In this first step multiple positions of the UAV are assumed known; think of a synthetic aperture. The only information about the tracked ground objects/features is the unit vector that points to the objects from the center of the camera. Two such vectors …
Functional Near-Infrared Spectroscopy For Hb And Hbo₂ Detection Using Remote Sensing, Rane M. Pierson
Functional Near-Infrared Spectroscopy For Hb And Hbo₂ Detection Using Remote Sensing, Rane M. Pierson
Theses and Dissertations
The goal of the work presented in this thesis is to develop a wireless, near-infrared (NIR) imaging system to provide flexibility and functionality to clinicians and researchers who require monitoring of blood profusion to tissue, muscles, or the brain. The prototype device uses a single stimulus/detection unit composed of an Epitex NIR LED with three wavelength options: 730, 805, and 850 nm, and an OPT101 photodiode detector. The device can be used to detect changes in the levels of oxygenated and deoxygenated hemoglobin in the body by measuring the amounts of absorbed and backscattered light at the wavelength associated with …
A System Level Approach To D-Fiber Electric Field Sensing, Joshua Monroe Kvavle
A System Level Approach To D-Fiber Electric Field Sensing, Joshua Monroe Kvavle
Theses and Dissertations
This dissertation presents the novel creation of a hybrid D-fiber electro-optic polymer electric field sensor. The sensor is made by removing a portion of the cladding from a D-shaped optical fiber, thus exposing the core to interaction with external stimulus. Then, an electro-optic polymer is deposited, partially replacing the core of the fiber. Next, the polymer is poled to endow it with electro-optic properties. This sensor is packaged in order to restore its mechanical strength. Because D-fiber is not intrinsically compatible with standard optical equipment it is fusion spliced to standard polarization maintaining fiber. Finally the sensor is tested for …
Towards A Universal Ultra-Thin Fluorinated Diamond-Like Carbon Coating For Nanoimprint Lithography Imprinters, Ryan Winfield Fillman
Towards A Universal Ultra-Thin Fluorinated Diamond-Like Carbon Coating For Nanoimprint Lithography Imprinters, Ryan Winfield Fillman
Theses and Dissertations
Nanoimprint lithography (NIL) has proven to achieve arbitrary, nanoscale features, over large areas, without the use of costly step-and-repeat UV lithography tools. The fidelity of the imprinted pattern depends on the elimination of the adhesion between the imprinted polymer and the imprinter upon withdrawal of the imprinter. The plasma deposition of a layer of fluorinated diamond-like carbon (F-DLC) has proven to be a successful anti-adhesion layer but in the past has required an entire diamond-like carbon (DLC) substrate. The requirement that the imprinter be made of DLC limits the imprinter processing and can limit the capabilities of NIL. DLC films …
Integration Of Multiple Data Types In 3-D Immersive Virtual Reality (Vr) Environments, George Demetrius Lecakes Jr.
Integration Of Multiple Data Types In 3-D Immersive Virtual Reality (Vr) Environments, George Demetrius Lecakes Jr.
Theses and Dissertations
Intelligent sensors have begun to play a key part in the monitoring and maintenance of complex infrastructures. Sensors have the capability not only to provide raw data, but also provide "information" by indicating the reliability of the measurements. The effect of this added information is a voluminous increase in the total data that is gathered. If an operator is required to perceive the state of a complex system, novel methods must be developed for sifting through enormous data sets. Virtual reality (VR) platforms are proposed as ideal candidates for performing this task-- a virtual world will allow the user to …
Construction Of Large Geo-Referenced Mosaics From Mav Video And Telemetry Data, Benjamin Kurt Heiner
Construction Of Large Geo-Referenced Mosaics From Mav Video And Telemetry Data, Benjamin Kurt Heiner
Theses and Dissertations
Miniature Aerial Vehicles (MAVs) are quickly gaining acceptance as a platform for performing remote sensing or surveillance of remote areas. However, because MAVs are typically flown close to the ground (1000 feet or less in altitude), their field of view for any one image is relatively small. In addition, the context of the video (where and at what orientation are the objects being observed, the relationship between images) is unclear from any one image. To overcome these problems, we propose a geo-referenced mosaicing method that creates a mosaic from the captured images and geo-references the mosaic using information from the …
Obstacle Avoidance, Visual Automatic Target Tracking, And Task Allocation For Small Unmanned Air Vehicles, Jeffery Brian Saunders
Obstacle Avoidance, Visual Automatic Target Tracking, And Task Allocation For Small Unmanned Air Vehicles, Jeffery Brian Saunders
Theses and Dissertations
Recent developments in autopilot technology have increased the potential use of micro air vehicles (MAVs). As the number of applications increase, the demand on MAVs to operate autonomously in any scenario increases. Currently, MAVs cannot reliably fly in cluttered environments because of the difficulty to detect and avoid obstacles. The main contribution of this research is to offer obstacle detection and avoidance strategies using laser rangers and cameras coupled with computer vision processing. In addition, we explore methods of visual target tracking and task allocation. Utilizing a laser ranger, we develop a dynamic geometric guidance strategy to generate paths around …
Offset Qpsk In Siso And Mimo Environments, Xiaoyu Dang
Offset Qpsk In Siso And Mimo Environments, Xiaoyu Dang
Theses and Dissertations
We demonstrate how the performance of offset quadrature phase-shift keying (OQPSK) and its variants of Feher-patented QPSK (FQPSK) and Shaped Offset QPSK (SOQPSK) (collectively known as the ARTM Tier-1 waveforms) in single input single output (SISO) system could change with the channel fading parameters. The bit error rate expression of offset QSPK and ATRM Tier-1 waveforms over the aeronautical telemetry multipath channel has been derived. Simulations show that for the case of a single multipath ray, the BER gets worse with increasing Γ for a fixed delay, and that the BER has a quasi-periodic property for fixed Γ and increasing …
Radio Frequency Interference Mitigation On The Very Small Array, Alan Joseph Stemmons
Radio Frequency Interference Mitigation On The Very Small Array, Alan Joseph Stemmons
Theses and Dissertations
Radio astronomical synthesis imaging arrays can create images with resolution much higher than can single dish telescopes. However, one of the biggest problems that imaging arrays face is radio frequency interference (RFI). This interference corrupts signals and prevents accurate image creation. Therefore, it is necessary to remove this interference. This thesis discusses the synthesis imaging procedure and array spatial filtering methods to remove interference, including Multiple Sidelobe Canceller (MSC), Subspace Projection (SP), and Cross-Subspace Projection (CSP). The CLEAN algorithm, an image restoration technique, is also discussed. Various improvements to the VSA are discussed, including upgrades to the hardware and software …
Design And Analysis Of A Dual-Mode Cascaded-Loop Frequency Synthesizer, Xiongliang Lai
Design And Analysis Of A Dual-Mode Cascaded-Loop Frequency Synthesizer, Xiongliang Lai
Theses and Dissertations
A new architecture for a frequency synthesizer with adjustable output frequency range and channel spacing is introduced. It is intended for the generation of closely spaced frequency channels in the GHz range while producing minimal spurious phase noise components. The architecture employs two independent phase-locked loops that are driven in cascade by a single reference oscillator. The approach provides fine resolution and wide bandwidth as well as low phase noise and should find application in many contemporary communication systems. The synthesizer can be operated in either of two different modes: nonfractional and mini-denominator fractional modes. The architecture produces no fractional …
An Efficient And Effective Implementation Of The Trust System For Power Grid Compartmentalization, Juan M. Carlos Gonzalez
An Efficient And Effective Implementation Of The Trust System For Power Grid Compartmentalization, Juan M. Carlos Gonzalez
Theses and Dissertations
As utility companies develop and incorporate new technologies, such as moving to utility Internet technology based architecture and standard; it is crucial that we do so with history in mind. We know that traditional utility protection and control systems were not designed with security in their top priorities. This presents a danger in an environment where near real-time responses are required to ensure safe operations. As a consequence, system security becomes a burden to the system rather than necessary protection. Unfortunately, technology implementation is not the only concern. The number of utility privately-owned companies has multiplied as the market has …
Growth, Characterization And Applications Of Multifunctional Ferroelectric Thin Films, Bo Xiao
Growth, Characterization And Applications Of Multifunctional Ferroelectric Thin Films, Bo Xiao
Theses and Dissertations
Ferroelectric materials have been extensively studied theoretically and experimentally for many decades. Their ferroelectric, piezoelectric, pyroelectric, dielectric and electro-optical properties offer great promise in various applications such as non-volatile random access memory devices, non linear optics, motion and thermal sensors, and tunable microwave devices. Advanced applications for high dielectric constant insulators and nonvolatile memories in semiconductor industry have led to a meteoric rise of interest in the ferroelectrics recently. As most studied and technically important ferroelectric materials, lead zirconate titanate (PZT) and barium strontium titanate (BST) are widely investigated to understand their properties for potential device applications. Using radio frequency …
System Identification Of An On Orbit Spacecraft's Antenna Dynamics, Christopher M. Sylvester
System Identification Of An On Orbit Spacecraft's Antenna Dynamics, Christopher M. Sylvester
Theses and Dissertations
As a result of previous efforts [Pachter, Barba, 2007] a tight control loop was designed to meet performance specifications while minimizing the feedback control system’s gains of a spacecraft mounted flexible antenna. Emphasis is now shifted to on orbit system identification of the antenna dynamics in order to increase nominal plant knowledge, estimate plant uncertainty bounds, as well as determine the disturbance band. Non-parametric system identification is undertaken. Knowledge of the plant dynamics along with the corresponding uncertainty bounds will provide for the design of a control system which meets the specifications (tracking and disturbance rejection) while at the same …
An Internal Representation For Adaptive Online Parallelization, Koy D. Rehme
An Internal Representation For Adaptive Online Parallelization, Koy D. Rehme
Theses and Dissertations
Future computer processors may have tens or hundreds of cores, increasing the need for efficient parallel programming models. The nature of multicore processors will present applications with the challenge of diversity: a variety of operating environments, architectures, and data will be available and the compiler will have no foreknowledge of the environment until run time. Adaptive Online Parallelization (ADOPAR) is a unifying framework that attempts to overcome diver sity by separating discovery and packaging of parallelism. Scheduling for execution may then occur at run time when diversity may best be resolved. This work presents a compact representation of parallelism based …
Fabrication And Device Applications Of Self Assembled Nanostructures, Bhargava Ram Kanchibotla V
Fabrication And Device Applications Of Self Assembled Nanostructures, Bhargava Ram Kanchibotla V
Theses and Dissertations
The spin dynamics of electrons in inorganic and organic semiconducting nanostructures has become an area of interest in recent years. The controlled manipulation of an electron’s spin, and in particular its phase, is the primary requirement for applications in quantum information processing. The phase decoheres in a time known as the transverse relaxation time or T2 time. We have carried out a measurement of the ensemble-averaged transverse spin relaxation time (T2*) in bulk and few molecules of the organic semiconductor tris-(8-hydroxyquinolinolato aluminum) or Alq3. The Alq3 system exhibits two characteristic T2* times: the longer of which is temperature independent and …
Real-Time Optical Flow Sensor Design And Its Application On Obstacle Detection, Zhaoyi Wei
Real-Time Optical Flow Sensor Design And Its Application On Obstacle Detection, Zhaoyi Wei
Theses and Dissertations
Motion is one of the most important features describing an image sequence. Motion estimation has been widely applied in structure from motion, vision-based navigation and many other fields. However, real-time motion estimation remains a challenge because of its high computational expense. The traditional CPU-based scheme cannot satisfy the power, size and computation requirements in many applications. With the availability of new parallel architectures such as FPGAs and GPUs, applying these new technologies to computer vision tasks such as motion estimation has been an active research field in recent years. In this dissertation, FPGAs have been applied to real-time motion estimation …
Removing Redundant Logic Pathways In Polymorphic Circuits, Hanseok Kim
Removing Redundant Logic Pathways In Polymorphic Circuits, Hanseok Kim
Theses and Dissertations
Evaluating the quality of software and circuit obfuscators is a research goal of great interest. However, there exists little research about evaluation of obfuscation effectiveness through analyzing and investigating redundancies found in the obfuscated variants. In this research, we consider programs represented as structural combinational circuits and then analyze obfuscated variants of those circuits through a tool that produces functionally equivalent variants based on subcircuit selection and replacement. We then consider how Boolean logic and reduction affects the size and levelization of circuit variants, giving us a concrete metric by which to consider obfuscation effectiveness. To accomplish these goals, we …