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Articles 6181 - 6210 of 11510

Full-Text Articles in Engineering

Inferring Gene Regulatory Networks From Expression Data Using Ensemble Methods, Janusz Slawek May 2014

Inferring Gene Regulatory Networks From Expression Data Using Ensemble Methods, Janusz Slawek

Theses and Dissertations

High-throughput technologies for measuring gene expression made inferring of the genome-wide Gene Regulatory Networks an active field of research. Reverse-engineering of systems of transcriptional regulations became an important challenge in molecular and computational biology. Because such systems model dependencies between genes, they are important in understanding of cell behavior, and can potentially turn observed expression data into the new biological knowledge and practical applications. In this dissertation we introduce a set of algorithms, which infer networks of transcriptional regulations from variety of expression profiles with superior accuracy compared to the state-of-the-art techniques. The proposed methods make use of ensembles of …

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An Experimental Study Of Bio-Inspired Force Generation By Unsteady Flow Features, Wesley N. Fassmann May 2014

An Experimental Study Of Bio-Inspired Force Generation By Unsteady Flow Features, Wesley N. Fassmann

Theses and Dissertations

As the understanding of the workings of the biological world expands, biomimetic designs increasingly move into the focus of engineering research studies. For this thesis, two studiesinvolving leading edge vortex generation for lift production as observed in nature were explored intheir respective flow regimes. The first study focused on the steady state analysis of streamwise vortices generated byleading edge tubercles of an adult humpback whale flipper. A realistic scaled model of a humpbackflipper was fabricated based on the 3D reconstruction from a sequence of 18 images taken whilecircumscribing an excised flipper of a beached humpback whale. Two complementary modelswith smooth …

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Flexible Slosh Diaphragm Modeling And Simulation In Propellant Tanks, Darren Vaughn Levine May 2014

Flexible Slosh Diaphragm Modeling And Simulation In Propellant Tanks, Darren Vaughn Levine

Theses and Dissertations

iquid sloshing and propellant distribution is an important field of research for aerospace applications such as launch vehicles and spacecraft. The propellant mass behavior can greatly influence vehicle dynamics, altering trajectories and structural loading distributions. In order to combat these concerns some propellant tanks employ thin elastomeric diaphragms to separate the fuel from the gas volumes and restrict the fluid's motion. The diaphragm’s flexible behavior is generally highly nonlinear, and various propellant fill levels and acceleration conditions can cause large deflections resulting in complex buckling and folding patterns. When complex and non-uniform deformations occur, there is potential for diaphragm wear …

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Analyzing Thermal And Mechanical Effects Of Pulsed Laser Irradiation On Tissues, Mohit Ganguly May 2014

Analyzing Thermal And Mechanical Effects Of Pulsed Laser Irradiation On Tissues, Mohit Ganguly

Theses and Dissertations

Pulsed lasers are known for their spatial and temporal specificity in delivering heat energy to the tissues. This is useful in laser ablation treatment mechanism where damage to the healthy tissues is highly undesired. However, the efficacy of the process is limited by the damage caused by the pulsed laser. A pulsed laser has both photothermal and photomechanical interaction with tissues. Photothermal interaction is caused by the rise in temperature due to the laser irradiation. This includes the denaturation of proteins, increased mitochondrial membrane permeability and ultimately vaporization. Photomechanical interaction causes the generation of pressure waves produced as a result …

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Resonant Coupling Of An Infrared Metasurface With Pmma, Michael Francis Finch May 2014

Resonant Coupling Of An Infrared Metasurface With Pmma, Michael Francis Finch

Theses and Dissertations

Resonance coupling between a metasurface or planar metamaterial and PMMA’s, polymethyl methacrylate, phonon resonance corresponding to the C=O molecular bond at 1733 cm-1 (52 THz) is investigated. Two metasurfaces, nano rod and nano slot, are modeled using ANSYS HFSS and measured material optical properties for gold and PMMA in inferred spectrum. Both metasurfaces exhibited normal mode splitting also known as avoidance crossing, quantum level repulsion, or vacuum Rabi splitting. Normal mode splitting is shown to be a result of coupling between the PMMA phonon resonance and the resonance of the metasurface. Analytical models, which are tied to physical descriptions, are …

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Infrared Leaky Wave Antenna Coupled Bolometer, Navaneeth Premkumar May 2014

Infrared Leaky Wave Antenna Coupled Bolometer, Navaneeth Premkumar

Theses and Dissertations

A four-element infrared leaky-wave antenna coupled bolometer was investigated with the goal of characterizing signal extraction as a long wave infrared (LWIR) detector. Simulations were carried out using Ansys HFSS. Various simple loading techniques were seen and their behavior characterized. A transmission line loaded antenna coupled bolometer was investigated using an incident-wave excitation and angle of sensing inaccuracies were observed. A position pertaining to the design criterion of angular scanning in frequency was then parametrically tuned for. The leaky-wave antenna was then simulated in the transmitting scenario. A waveport fed case was explored and far-field pattern generated. Transmission line losses …

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Overcoming Hard Problems In Software Testing With Testing As A Service, Brianna Floss May 2014

Overcoming Hard Problems In Software Testing With Testing As A Service, Brianna Floss

Theses and Dissertations

Software testing is a crucial phase of the software development lifecycle, responsible for assuring that the system under test meets quality standards, requirements, and consumer needs. Unfortunately, software testing is not without flaws. Some problems are timeless while others are brought on by new technologies and methodologies. As software systems grow in size and complexity, quality becomes significantly more difficult to ensure. With recent advancements in cloud computing, the internet’s vast and elastic resources are available for testing. Testing as a Service (TaaS) offers accessible services that handle testing activities to consumers on a pay-as-you-test basis in hopes of providing …

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Nanowire Zinc Oxide Mosfet Pressure Sensor, William Clavijo Apr 2014

Nanowire Zinc Oxide Mosfet Pressure Sensor, William Clavijo

Theses and Dissertations

Fabrication and characterization of a new kind of pressure sensor using self-assembly Zinc Oxide (ZnO) nanowires on top of the gate of a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) is presented. Self-assembly ZnO nanowires were fabricated with a diameter of 80 nm and 800 nm height (80:8 aspect ratio) on top of the gate of the MOSFET. The sensor showed a 110% response in the drain current due to pressure, even with the expected piezoresistive response of the silicon device removed from the measurement. The pressure sensor was fabricated through low temperature bottom up ultrahigh aspect ratio ZnO nanowire growth using anodic …

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Dynamic Task-Allocation For Unmanned Aircraft Systems, Tim Bakker Apr 2014

Dynamic Task-Allocation For Unmanned Aircraft Systems, Tim Bakker

Theses and Dissertations

This dissertation addresses improvements to a consensus based task allocation algorithms for improving the Quality of Service in multi-task and multi-agent environments. Research in the past has led to many centralized task allocation algorithms where a central computation unit is calculating the global optimum task allocation solution. The centralized algorithms are plagued by creating a single point of failure and the bandwidth needed for creating consistent and accurate situational awareness off all agents. This work will extend upon a widely researched decentralized task assignment algorithm based on the consensus principle. Although many extensions have led to improvements of the original …

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Design Of A Small Form-Factor Flight Control System, Garrett Ward Apr 2014

Design Of A Small Form-Factor Flight Control System, Garrett Ward

Theses and Dissertations

This work outlines a design for a small form-factor flight control system designed to fly in a wide variety of airframes. The system was designed with future expansion in mind while providing a complete, all-in-one solution to meet present needs. This system as presented meets most needs while remaining relatively low cost. It has a completely integrated IMU solution as well as on- board GPS. It is capable of basic waypoint navigation. This solution was testing using software and hardware-in-the-loop simulation which proved its functionality.

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Synthesis And Characterization Of Clickable Dendrimer Hydrogels For Ocular Drug Delivery, Jingfei Tian Apr 2014

Synthesis And Characterization Of Clickable Dendrimer Hydrogels For Ocular Drug Delivery, Jingfei Tian

Theses and Dissertations

Topical medication is a standard treatment for glaucoma. However, frequent dosing makes the therapy inconvenient and patient unfriendly. There is a great need to develop new topical formulations that provide long lasting noninvasive drug release. In this thesis, novel clickable dendrimer hydrogels for anti-glaucoma drug delivery were synthesized and characterized. Polyamidoamine (PAMAM) dendrimers have been widely applied for drug delivery. The physical characteristics they possess include monodispersity, water solubility, encapsulation ability, and a large number of surface groups. Polycationic PAMAM dendrimer G3 was surface modified with alkyne-PEG5-acid and then reacted with polyethylene glycol bisazide (PEG-BA, 1100 gmol-1) through click chemistry …

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Power Side-Channel Dac Implementations For Xilinx Fpgas, Daniel Chase Savory Apr 2014

Power Side-Channel Dac Implementations For Xilinx Fpgas, Daniel Chase Savory

Theses and Dissertations

This thesis presents a novel power side-channel DAC (PS-DAC) which is constructed from user-controllable short circuits in FPGAs and which manipulate overall system power through dynamic power dissipation. Alternately, similar PS-DACs are created using shift-register primitives(SRL16E) which manipulate system power through switching logic, for means of comparison with short-circuit-based PS-DACs. PS-DACs are created of various sizes using both short-circuit-based and shift-register-based methods. These PS-DACs are characterized in terms of output linearity,monotonicity, and frequency distortion. Applications explored in this thesis which use PS-DAC technology include a Simple Power Analysis (SPA) side-channel transmitter, and a frequency watermarking application. These applications serve as …

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Lung Alveolar And Tissue Analysis Under Mechanical Ventilation, Trenicka Rolle Apr 2014

Lung Alveolar And Tissue Analysis Under Mechanical Ventilation, Trenicka Rolle

Theses and Dissertations

Mechanical ventilation has been a major therapy used by physicians in support of surgery as well as for treating patients with reduced lung function. Despite its many positive outcomes and ability to maintain life, in many cases, it has also led to increased injury of the lungs, further exacerbating the diseased state. Numerous studies have investigated the effects of long term ventilation with respect to lungs, however, the connection between the global deformation of the whole organ and the strains reaching the alveolar walls remains unclear. The walls of lung alveoli also called the alveolar septum are characterized as a …

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Termediator-Ii: Identification Of Interdisciplinary Term Ambiguity Through Hierarchical Cluster Analysis, Owen G. Riley Apr 2014

Termediator-Ii: Identification Of Interdisciplinary Term Ambiguity Through Hierarchical Cluster Analysis, Owen G. Riley

Theses and Dissertations

Technical disciplines are evolving rapidly leading to changes in their associated vocabularies. Confusion in interdisciplinary communication occurs due to this evolving terminology. Two causes of confusion are multiple definitions (overloaded terms) and synonymous terms. The formal names for these two problems are polysemy and synonymy. Termediator-I, a web application built on top of a collection of glossaries, uses definition count as a measure of term confusion. This tool was an attempt to identify confusing cross-disciplinary terms. As more glossaries were added to the collection, this measure became ineffective. This thesis provides a measure of term polysemy. Term polysemy is effectively …

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Enhancement Of Mass Transfer And Electron Usage For Syngas Fermentation, James J. Orgill Apr 2014

Enhancement Of Mass Transfer And Electron Usage For Syngas Fermentation, James J. Orgill

Theses and Dissertations

Biofuel production via fermentation is produced primarily by fermentation of simple sugars. Besides the sugar fermentation route, there exists a promising alternative process that uses syngas (CO, H2, CO2) produced from biomass as building blocks for biofuels. Although syngas fermentation has many benefits, there are several challenges that still need to be addressed in order for syngas fermentation to become a viable process for producing biofuels on a large scale. One challenge is mass transfer limitations due to low solubilities of syngas species. The hollow fiber reactor (HFR) is one type of reactor that has the potential for achieving high …

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Mammary Epithelial Cells Cultured Onto Non-Woven Nanofiber Electrospun Silk-Based Biomaterials To Engineer Breast Tissue Models, Yas Maghdouri-White Apr 2014

Mammary Epithelial Cells Cultured Onto Non-Woven Nanofiber Electrospun Silk-Based Biomaterials To Engineer Breast Tissue Models, Yas Maghdouri-White

Theses and Dissertations

Breast cancer is one of the most common types of cancer affecting women in the world today. To better understand breast cancer initiation and progression modeling biological tissue under physiological conditions is essential. Indeed, breast cancer involves complex interactions between mammary epithelial cells and the stroma, both extracellular matrix (ECM) and cells including adipocytes (fat tissue) and fibroblasts (connective tissue). Therefore, the engineering of in vitro three-dimensional (3D) systems of breast tissues allows a deeper understanding of the complex cell-cell and cell-ECM interactions involved during breast tissue development and cancer initiation and progression. Furthermore, such 3D systems may provide a …

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Tuning And Optimization Of Silk Fibroin Gels For Biomedical Applications, Michael Marin Apr 2014

Tuning And Optimization Of Silk Fibroin Gels For Biomedical Applications, Michael Marin

Theses and Dissertations

Biocompatible and biodegradable porous materials based on silk fibroin (SF), a natural protein derived from the Bombyx mori silkworm, are being extensively investigated for use in biomedical applications including mammalian cell bioprocessing, tissue engineering, and drug delivery applications. In this work, low-pressure, gaseous CO2 is used as an acidifying agent to fabricate SF hydrogels. This low-pressure CO2 acidification method is compared to an acidification method using high-pressure CO2 to demonstrate the effect of CO2 mass transfer and pressure on SF sol-gel kinetics. The effect of SF molecular weight on the sol-gel kinetics is determined using the low-pressure CO2 method. The …

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Engineering Cell-Free Systems For Vaccine Development, Self-Assembling Nanoparticles And Codon Reassignment Applications, Mark T. Smith Apr 2014

Engineering Cell-Free Systems For Vaccine Development, Self-Assembling Nanoparticles And Codon Reassignment Applications, Mark T. Smith

Theses and Dissertations

This dissertation reports on the technology of cell-free protein synthesis (CFPS) including 1) stabilized lyophilized cell-free systems and 2) enhanced heterogeneous cell extracts. This work further considers applications of CFPS systems in 1) rapid vaccine development, 2) functional virus-based nanoparticles, 3) site-specific protein immobilization, and 4) expanding the language of biology using unnatural amino acids. CFPS technology is a versatile protein production platform that has many features unavailable in in vivo expression systems. The primary benefit cell-free systems provide is the direct access to the reaction environment, which is no longer hindered by the presence of a cell-wall. The “openness" …

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Biomechanical Applications And Modeling Of Quantum Nano-Composite Strain Gauges, Taylor David Remington Apr 2014

Biomechanical Applications And Modeling Of Quantum Nano-Composite Strain Gauges, Taylor David Remington

Theses and Dissertations

Biological tissues routinely experience large strains and undergo large deformations during normal physiologic activity. Biological tissue deformation is well beyond the range of standard strain gauges, and hence must often be captured using expensive and non-portable options such as optical marker tracking methods that may rely upon significant post-processing. This study develops portable gauges that operate in real time and are compatible with the large strains seen by biological materials. The new gauges are based on a relatively new technique for quantifying large strain in real-time (up to 40 %) by use of a piezoresistive nano-composite strain gauge. The nano-composite …

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Unattended Remotely Operated Deep-Water Sediment Oxygen Demand Chambers, Drake Theodore Mailes Apr 2014

Unattended Remotely Operated Deep-Water Sediment Oxygen Demand Chambers, Drake Theodore Mailes

Theses and Dissertations

Dissolved oxygen (DO) depletion in a water body is governed by two primary mechanisms: biological oxygen demand (BOD) from the water column, and sediment oxygen demand (SOD) from sediments. SOD is the dominant oxygen sink in many water bodies; measurements show as much as 95% of oxygen consumption as attributable to SOD (Truax, Shindala, & Sartain, 1996). Measuring SOD in surface water impoundments is an essential component in evaluating and an important input for modeling the health of a water body. Traditional SOD measurement methods are difficult in deeper waters, such as in reservoirs or lakes, because traditional SOD measurement …

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High-Performance Doped Strontium Iodide Crystal Growth Using A Modified Bridgman Method, Emmanuel Rowe Mar 2014

High-Performance Doped Strontium Iodide Crystal Growth Using A Modified Bridgman Method, Emmanuel Rowe

Theses and Dissertations

The importance of gamma-ray spectroscopy – the science of determining the distribution of energy in a gamma field – can rarely be overstated. High performance scintillators for gamma-ray spectroscopy in Nuclear Nonproliferation applications and homeland security require excellent energy resolution to distinguish neighboring element and isotope lines while minimizing the time and exposure to do so. Semiconductor detectors operate by converting incident photons directly into electrical pulses, but often have problems of high costs due to constituent segregation and surface states as is the case for Cadmium Zinc Telluride. The ideal scintillator material for gamma spectrometer will therefore requires high …

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Strength Of Masonry Grout Made With Expanded Shale, Allison Tanner Mar 2014

Strength Of Masonry Grout Made With Expanded Shale, Allison Tanner

Theses and Dissertations

Light-weight aggregate has been used successfully for structural and non-structural applications, and its most common use has been in light-weight concrete. Limited research has been done on light-weight grout though and there are no standards in place. The research performed in this study is intended to increase the knowledge of light-weight grout specifically made with expanded shale aggregate. The research presented herein is a pilot study and consists of preliminary aggregate and grout testing that resulted in the mix design of six grout types: three fine grout designs and three coarse grout designs. Conventional normal-weight aggregate was employed in the …

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Sensitivity Of Electrochemical Impedance Spectroscopy Measurements To Concrete Bridge Deck Properties, Hillary Mckenna Argyle Mar 2014

Sensitivity Of Electrochemical Impedance Spectroscopy Measurements To Concrete Bridge Deck Properties, Hillary Mckenna Argyle

Theses and Dissertations

Numerous methods have been developed to measure corrosion potential relating to chloride infiltration in concrete, including an emerging application of electrochemical impedance spectroscopy (EIS). EIS involves measurements of electrical impedance to evaluate the corrosion potential of steel reinforcement in concrete. With EIS, current is injected vertically into the concrete bridge deck between the surface and the embedded reinforcing steel, usually the top mat, to evaluate the degree to which the reinforcing steel is protected from chloride infiltration by the entire bridge deck system. The objectives of this research were to 1) investigate the sensitivity of EIS measurements obtained at various …

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Public Safety At Low-Head Dams: Fatality Database And Physical Model Of Staggered Deflector Retrofit Alternative, Edward William Kern Mar 2014

Public Safety At Low-Head Dams: Fatality Database And Physical Model Of Staggered Deflector Retrofit Alternative, Edward William Kern

Theses and Dissertations

Low-head dams can cause dangerous currents near the downstream face of the structure. Fatalities at low-head dams are poorly documented. This thesis introduces a website with an interactive map and database of fatalities at low-head dams in the United States. The purpose of the web site is to generate interest among the general public to increase support to remediate dangerous structures and to serve as a tool for public education. The user interface allows the general public to browse fatal incidents by geographic location and to read incident circumstances. The site allows submission of public contributions including all metadata needed …

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Determining Dispersion Coefficients In Sewer Networks, Joshua G. Wagstaff Mar 2014

Determining Dispersion Coefficients In Sewer Networks, Joshua G. Wagstaff

Theses and Dissertations

This work determines a suitable value for a dispersion coefficient to be used in the One-Dimensional Advection-Dispersion equation to model dispersion within sewer collection systems. Dispersion coefficients for sewer systems have only recently begun to be studied, and there is not yet an established value that is commonly accepted. The work described in this paper aimed, through observational study, to find a suitable value to be used. Salt tracers were placed in two separate reaches of sewer line. The first line studied was a straight, linear reach of sewer that included three manholes. The tracer was placed in the first …

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Multi-Rotor--Aided Three-Dimensional 802.11 Wireless Heat Mapping, Scott James Pack Mar 2014

Multi-Rotor--Aided Three-Dimensional 802.11 Wireless Heat Mapping, Scott James Pack

Theses and Dissertations

Traditional wireless site surveys produce a heat-map of link strength or quality over a target area, usually on the ground plane. In recent years research has gone into using aerial drones in network attack and surveillance, making three dimensional awareness of wireless coverage areas of interest. A multi-rotor drone and data collection module were built and tested as part of this research. Site assessments were conducted both in open space and near structures. Collected data was interpolated across the target area, and visualized as points and contours. These visualizations were exported to a Keyhole Markup Language (KML) for visualization in …

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Development Of A Chloride Concentration Sampling Protocol For Concrete Bridge Decks, Sharlan Renae Montgomery Mar 2014

Development Of A Chloride Concentration Sampling Protocol For Concrete Bridge Decks, Sharlan Renae Montgomery

Theses and Dissertations

As the primary cause of concrete bridge deck deterioration in the United States is corrosion of the steel reinforcement as a result of the application of chloride-based deicing salts, chloride concentration testing is among the most common techniques for evaluating the condition of a concrete bridge deck. The objectives of this research were to 1) compare concrete drilling and powder collection techniques to develop a sampling protocol for accurately measuring chloride concentrations and 2) determine the number of chloride concentration test locations necessary for adequately characterizing the chloride concentration of a given bridge deck. Laboratory experiments on concrete drilling and …

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Passive And Electronically Steered Array Planar Feeds For Satellite Communications, Kyle C. Browning Mar 2014

Passive And Electronically Steered Array Planar Feeds For Satellite Communications, Kyle C. Browning

Theses and Dissertations

As the need for more bandwidth increases, satellite communication (SatCom) terminals are forced to climb higher in frequency. Higher frequency means greater propagation losses, and so antenna gain and sensitivity have to increase. The higher the gain, the more difficult it is to point the antenna. To make matters even more challenging, consumers are requesting satellite links in harsher environments and on moving vehicle and planes. In order to meet today's challenges and improve on dish feeds, research is ongoing to replace fixed-beam feedhorns with smaller, cheaper, and lighter PCB based antennas and to develop low-cost electronically steered array feeds …

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Application Improvements Of Slab-Coupled Optical Fiber Sensors, Spencer L. Chadderdon Mar 2014

Application Improvements Of Slab-Coupled Optical Fiber Sensors, Spencer L. Chadderdon

Theses and Dissertations

This dissertation explores techniques for improving slab-coupled optical fiber sensor (SCOS) technology for use in specific applications and sensing configurations. SCOS are advantageous for their small size and all-dielectric composition which permit non-intrusive measurement of electric fields within compact environments; however, their small size also limits their sensitivity. This work performs a thorough analysis of the factors contributing to the performance of SCOS and demonstrates methods which improve SCOS, while maintaining its small dimensions and high level of directional sensitivity. These improvements include increasing the sensitivity by 9x, improving the frequency response to include sub 300 kHz frequencies, and developing …

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Modulation And Synchronization For Aeronautical Telemetry, Christopher G. Shaw Mar 2014

Modulation And Synchronization For Aeronautical Telemetry, Christopher G. Shaw

Theses and Dissertations

Aeronautical telemetry systems have historically been implemented with constant envelope modulations like CPM. Shifts in system constraints including reduced available bandwidth and increased throughput demands have caused many in the field to reevaluate traditional methods and design practices. This work examines the costs and benefits of using APSK for aeronautical telemetry instead of CPM. Variable rate turbo codes are used to improve the power efficiency of 16- and 32-APSK. Spectral regrowth in nonlinear power amplifiers when driven by non-constant envelope modulation is also considered. Simulation results show the improved spectral efficiency of this modulation scheme over those currently defined in …

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