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Theses and Dissertations

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Full-Text Articles in Engineering

Ecad To Mcad Interoperability For Automated Enclosure Design, Adam C. Wilcox Nov 2008

Ecad To Mcad Interoperability For Automated Enclosure Design, Adam C. Wilcox

Theses and Dissertations

Enclosure design is the process of creating a package that will support and protect enclosed circuitry. Electronic enclosures are used in almost all industries, such as aerospace, automotive, naval, computer, toy, etc. Many designers use computer aided design (CAD) packages to aid them in creating these enclosures. Enclosure creation involves a working knowledge of the physics behind electrical and mechanical systems. Each of these engineering disciplines has separate CAD packages with their own set of rules, programming language, and interfaces. This creates a barrier for communication flow between electrical CAD (ECAD) and mechanical CAD (MCAD). The purpose of this thesis …

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Design Of A Three-Passage Low Reynolds Number Turbine Cascade With Periodic Flow Conditions, Daniel R. Rogers Nov 2008

Design Of A Three-Passage Low Reynolds Number Turbine Cascade With Periodic Flow Conditions, Daniel R. Rogers

Theses and Dissertations

A numerical method for modeling a low Reynolds number turbine blade, the L1M, is presented along with the pitfalls encountered. A laminar solution was confirmed to not accurately predict the flow features known in low Reynolds number turbine blade flow. Three fully turbulent models were then used to try to predict the separation and reattachment of the flow. These models were also found to be insufficient for transitioning flows. A domain was created to manually trip the laminar flow to turbulent flow using a predictive turbulence transition model. The trip in the domain introduced an instability in the flow field …

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Crashes In The Vicinity Of Major Crossroads, Charles G. Allen Nov 2008

Crashes In The Vicinity Of Major Crossroads, Charles G. Allen

Theses and Dissertations

Major crossroads are designed to facilitate the conflicting movements of numerous vehicles in a manner that is both safe and efficient. Accesses located within the functional areas of major crossroads add complication to intersection activity due to additional conflicts arising from ingressing and egressing movements at the accesses. In this research, the impact of accesses on crashes within major crossroad functional areas was analyzed. Specifically, the effects of access spacing within functional areas and access setback from intersections were addressed. In order to conduct the analysis, the functional areas of 159 signalized major arterial crossroads across the state of Utah …

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Corrosion Damage Studies Through Microscopy And Stress Analysis, Ronak Patel Nov 2008

Corrosion Damage Studies Through Microscopy And Stress Analysis, Ronak Patel

Theses and Dissertations

Corrosion is the destructive result of chemical reaction between a metal or metal alloy and its environment. Airplanes, power generating plants, chemical process and manufacturing plants, concrete structure, and many others which widely uses aluminum alloy and stainless steel alloys are subjected to corrosion. The estimated cost of corrosion damage is in order of 3 to 5 percent of gross national product (GNP). Out of all forms of corrosion, pitting corrosion is most commonly observed in aluminum alloy 2024 and stainless steel type 316. There is a need to study the stress environment around the pits in order to predict …

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Foundational Data Repository For Numeric Engine Validation, Jason Michael Hollingsworth Nov 2008

Foundational Data Repository For Numeric Engine Validation, Jason Michael Hollingsworth

Theses and Dissertations

Many different numeric models have been created to address a variety of hydraulic and hydrologic engineering applications. Each utilizes formulations and numeric methods to represent processes such as contaminant transport, coastal circulation, and watershed runoff. Although one process may be adequately represented by a model, this does not guarantee that another process will be represented even if that process is similar. For example, a model that computes subcritical flow does not necessarily compute supercritical flow. Selecting an appropriate numeric model for a situation is a prerequisite to obtaining accurate results. Current policies and resources do not provide adequate guidance in …

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Effect Of Initial Scarification And Overlay Treatment Timing On Chloride Concentrations In Concrete Bridge Decks, Curtis Daniel Nolan Nov 2008

Effect Of Initial Scarification And Overlay Treatment Timing On Chloride Concentrations In Concrete Bridge Decks, Curtis Daniel Nolan

Theses and Dissertations

Considering the pervasive presence of chlorides in concrete bridge decks, bridge engineers have a critical responsibility to perform proper and effective preventive maintenance and rehabilitation operations. Bridge engineers often perform scarification and overlay (SO) procedures on concrete bridge decks to minimize the corrosion of reinforcing steel due to chloride ingress. Given the need to develop guidelines for the initial timing of SO treatments, the specific objectives of this research were to collect information from several department of transportation (DOT) personnel about their SO procedures and, subsequently, to determine the recommended timing of initial SO procedures on concrete bridge decks for …

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Median Crossover Crashes In The Vicinity Of Interchanges On Utah Interstates, Katherine Elaine Winters Nov 2008

Median Crossover Crashes In The Vicinity Of Interchanges On Utah Interstates, Katherine Elaine Winters

Theses and Dissertations

While not accounting for a significant proportion of overall crashes, median crossover crashes in the state of Utah do account for a significant proportion of interstate fatalities. Due to the seriousness of median crossover crashes in the state of Utah, the need exists to evaluate the impact of median crossover crashes in the state, to identify locations where median crossover crashes may be occurring at particularly high rates, and to identify methods to help mitigate these crashes. Previous research has noted that median crossover crash rates appear to increase in the vicinity of interchanges. The purpose of this research, therefore, …

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Wire-Braced Semirigid Elevated Rotor System Concept For A Human-Powered Helicopter, Jonathan Richard Silvester Nov 2008

Wire-Braced Semirigid Elevated Rotor System Concept For A Human-Powered Helicopter, Jonathan Richard Silvester

Theses and Dissertations

In order for a human-powered helicopter (HPH) to fly, lifting the weight of its human pilot-engine and the weight of its own structure, the rotary wings need to be extremely large and exceptionally lightweight. Through centuries of dreaming and decades of modern attempts, no design so far has been able to obtain the combination of an adequately large rotor size, sufficiently lightweight structure, and an inherently stable aircraft. This thesis describes a concept of a wire-braced semi-rigid elevated rotor system for a proposed HPH. Then, using scale models and quantitative analysis, tests a series of supporting hypotheses in order to …

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Lean Six Sigma As A Source Of Competitive Advantage, Alessandro Giorgio Cavallini Nov 2008

Lean Six Sigma As A Source Of Competitive Advantage, Alessandro Giorgio Cavallini

Theses and Dissertations

Anecdotal data affirms that companies applying Lean Six Sigma in their operations not only deliver higher quality products and services, but also obtain superior financial results. The goal of this research was to empirically verify anecdotal data. The study proposed to analyze a group of publicly traded manufacturing companies with the intent of verifying if a correlation exists between companies being lean and the attainment of superior returns on investments. The researcher performed a series of statistical tests comparing key Financial Performance Indicators (FPI) extracted from annual reports (10-K) from a large pool of companies. The outcome of this study …

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Angiogenic Potential Of Human Macrophages On Electrospun Bioresorbable Vascular Grafts, Koyal Garg Nov 2008

Angiogenic Potential Of Human Macrophages On Electrospun Bioresorbable Vascular Grafts, Koyal Garg

Theses and Dissertations

The aim of this study was to investigate macrophage interactions with electrospun scaffolds and quantify the expression of vital angiogenic growth factors in vitro. This study will further help in evaluating the potential of these electrospun constructs as vascular grafts for tissue repair and regeneration in situ. Human peripheral blood macrophages were seeded in serum free media on electrospun (10 mm) discs of polydioxanone (PDO), elastin and PDO:elastin blends (50:50, 70:30 and 90:10). The growth factor secretion was analyzed by ELISA. Macrophages produced high levels of vascular endothelial growth factor (VEGF) and acidic fibroblast growth factor (aFGF). Transforming growth factor …

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Surface Relief D-Fiber Bragg Gratings For Sensing Applications, Tyson Lee Lowder Oct 2008

Surface Relief D-Fiber Bragg Gratings For Sensing Applications, Tyson Lee Lowder

Theses and Dissertations

This dissertation presents the novel creation of a surface relief fiber Bragg grating on the flat surface of a D-shaped optical fiber. In order to produce an efficient surface relief grating the grating must be etched into the surface of the glass fiber close to the core. A short etch that removes the cladding above the core is performed in order to decrease the core-to-flat distance and allow the light to interact with the grating on the flat surface. Due to the unique D-shape of the optical fiber the mechanical integrity of the fiber remains high even after the fabrication …

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Spin Transport Studies In Nanoscale Spin Valves And Magnetic Tunnel Junctions, Sridhar Patibandla Oct 2008

Spin Transport Studies In Nanoscale Spin Valves And Magnetic Tunnel Junctions, Sridhar Patibandla

Theses and Dissertations

Spintronics or electronics that utilizes the spin degree of freedom of a single charge carrier (or an ensemble of charge carriers) to store, process, sense or communicate data and information is a rapidly burgeoning field in electronics. In spintronic devices, information is encoded in the spin polarization of a single carrier (or multiple carriers) and the spin(s) of these carrier(s) are manipulated for device operation. This strategy could lead to devices with low power consumption. This dissertation investigates spin transport in one dimensional and two dimensional semiconductors, with a view to applications in spintronic devices.

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A Mechanistic Investigation Of Nitrogen Evolution In Pulverized Coal Oxy-Fuel Combustion, Andrew John Mackrory Oct 2008

A Mechanistic Investigation Of Nitrogen Evolution In Pulverized Coal Oxy-Fuel Combustion, Andrew John Mackrory

Theses and Dissertations

Oxy-fuel combustion is an enabling technology for capture of CO2 from coal combustion, the economics of which depends strongly on the ability of the process to produce low NOX emissions. The literature contains many reports of lower NOX emissions from oxy-fuel combustion but the reasons for this are not fully understood. The objective of this work was to gain understanding of nitrogen evolution under pulverized coal oxy-fuel conditions. Pulverized coal was burned in a once-through, down-fired, laminar flow reactor. Nitrogen compounds and other combustion species were measured at the reactor centerline as a function of distance from the burner. Dry …

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Pile Downdrag During Construction Of Two Bridge Abutments, Brian Keith Sears Oct 2008

Pile Downdrag During Construction Of Two Bridge Abutments, Brian Keith Sears

Theses and Dissertations

Two steel pipe piles in place in abutments for two different bridge constructions sites were instrumented with strain gauges to measure the magnitude of negative skin friction. The piles were monitored before, during and up to 19 months after construction was completed. The load versus depth and time in each pile is discussed. Maximum observed dragloads ranged from 98 to 127 kips. A comparison with two methods for calculating dragloads is presented. Both comparison methods were found to be conservative, with the Briaud and Tucker (1997) approach more closely estimating the observed load versus depth behavior.

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Design And Analysis Of A Positively Engaged Continuously Variable Transmission, Brandon Levi Haupt Oct 2008

Design And Analysis Of A Positively Engaged Continuously Variable Transmission, Brandon Levi Haupt

Theses and Dissertations

With energy demands at an all time high, mechanical power systems are under great scrutiny. Substantial efforts are being made throughout the world to reduce energy use in common mechanical systems such as the internal combustion engine and transmission system. Eliminating or reducing efficiency losses in the transmission is a potential source of improving the efficiency of the system. To do so, various alternative types of transmissions are being investigated. At Brigham Young University, development of a Positively Engaged Continuously Variable Transmission (PECVT) is progressing. In addition to the efficiency increases that would occur as a result of operating the …

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A Detailed Look At The Omega-K Algorithm For Processing Synthetic Aperture Radar Data, Matthew A. Tolman Oct 2008

A Detailed Look At The Omega-K Algorithm For Processing Synthetic Aperture Radar Data, Matthew A. Tolman

Theses and Dissertations

In this thesis, the Omega-k algorithm used for processing stripmap synthetic aperture radar (SAR) data is explored in detail. While the original Omega-k algorithm does not achieve the same SNR as a matched filter, a modification is presented which enables the algorithm to nearly achieve that SNR. It is shown that the focused point spread function obtained when the Omega-k algorithm is used differs in important ways from the output of a modified version of the matched filter. Spread out sidelobes and a stretched mainlobe are observed when the data is processed by the Omega-k algorithm. These differences may increase …

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Extension Of Viscoplasticity Based On Overstress To Capture The Effects Of Prior Aging On The Time Dependent Deformation Behavior Of A High-Temperature Polymer: Experiments And Modeling, Amber J. W. Mcclung Oct 2008

Extension Of Viscoplasticity Based On Overstress To Capture The Effects Of Prior Aging On The Time Dependent Deformation Behavior Of A High-Temperature Polymer: Experiments And Modeling, Amber J. W. Mcclung

Theses and Dissertations

The inelastic deformation behavior of PMR-15 neat resin, a high-temperature thermoset polymer, was investigated at 288 degrees C. The experimental program was designed to explore the influence of strain rate on tensile loading, unloading, and strain recovery behaviors. In addition, the effect of the prior strain rate on the relaxation response of the material, as well as on the creep behavior following strain controlled loading were examined. The experimental data were modeled with the Viscoplasticity Based on Overstress (VBO) theory. A systematic procedure for determining model parameters was developed and the model was employed to predict the response of the …

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Effects Of Environmental Factors On Construction Of Soil-Cement Pavement Layers, John E. Michener Sep 2008

Effects Of Environmental Factors On Construction Of Soil-Cement Pavement Layers, John E. Michener

Theses and Dissertations

The specific objectives of this research were to quantify the effects of certain environmental factors on the relative strength loss of soil-cement subjected to compaction delay and to develop a numerical tool that can be easily used by engineers and contractors for determining a maximum compaction delay time for a given project. These objectives were addressed through extensive laboratory work and statistical analyses. The laboratory work involved testing an aggregate base material and a subgrade soil, each treated with two levels of cement. Environmental factors included in the experimentation were wind speed, temperature, and relative humidity, and three levels of …

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Mechanistic Investigation Of Ash Deposition In Pulverized-Coal And Biomass Combustion, Shrinivas Sadashiv Lokare Sep 2008

Mechanistic Investigation Of Ash Deposition In Pulverized-Coal And Biomass Combustion, Shrinivas Sadashiv Lokare

Theses and Dissertations

This investigation details the effects of fuel constituents on ash deposition through systematic experimental and theoretical analyses of fundamental particle experiments and a suite of fuels with widely varying inorganic contents and compositions. The experiments were carried out in the Multifuel Flow Reactor (MFR) at Brigham Young University. Fuels included several biomass fuels (straw, sawdust and mixtures of straw-sawdust with other additives such as Al(OH)3, CaCO3, etc.) and four commercially-used coals (Illinois#6, Powder River Basin – Caballo and Cordero, Blind Canyon, and Lignite – Beulah Zap). The data from the series of experiments quantitatively illustrate the effects of fuel properties, …

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Verification Of Asphalt Concrete Performance Prediction Using Level 2 And Level 3 Inputs Of Mechanistic-Empirical Pavement Design Guide For Flexible Pavements Of The State Of New Jersey, Nusrat Siraj Sep 2008

Verification Of Asphalt Concrete Performance Prediction Using Level 2 And Level 3 Inputs Of Mechanistic-Empirical Pavement Design Guide For Flexible Pavements Of The State Of New Jersey, Nusrat Siraj

Theses and Dissertations

The purpose of this thesis is to present the results of the verification study of the Mechanistic-Empirical Pavement Design Guide (M-EPDG) using level 2 and level 3 inputs. In addition, the challenges of verification of the predicted performance with the help of field-measured data of existing flexible pavements are also presented. In this study, twenty-five sections were analyzed covering a broad range of soil, environmental conditions, traffic volumes and pavement structures observed in the state of New Jersey. Predicted performance of various distresses, such as rutting, alligator cracking, longitudinal cracking, thermal cracking and International Roughness Index (IRI) were verified for …

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Pylon Effects On A Scramjet Cavity Flameholder Flowfield, Andrew B. Freeborn Sep 2008

Pylon Effects On A Scramjet Cavity Flameholder Flowfield, Andrew B. Freeborn

Theses and Dissertations

Cavity flameholders in supersonic combustion ramjet (scramjet) combustors, while effective, fail to take advantage of the full combustor volume. Adding a pylon to the leading edge of a cavity flameholder generates a flowfield increasing mass exchange between the cavity and main combustor flow, increasing the mixing interface between flameholder products and main combustor flow, and exhibiting minimal Reynolds number effects. To demonstrate this modified flowfield driven by supersonic expansion behind the pylon, pylon-cavity flameholder flowfield data were obtained through a combination of wind tunnel experimentation and steady-state computational fluid dynamics (CFD). Flowfield effects of the pylon-cavity were examined at a …

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Hypermixer Pylon Fuel Injection For Scramjet Combustors, Jason C. Doster Sep 2008

Hypermixer Pylon Fuel Injection For Scramjet Combustors, Jason C. Doster

Theses and Dissertations

Fueling the core airflow of a circular or elliptical scramjet combustor cross-section often requires intrusive geometries. Intrusive geometries can distribute the fuel evenly across the combustor cross-section and act as a flameholder for the fuel/air mixture. Compared to conventional transverse or angled wall injection, intrusive geometries allow easier penetration into the core combustor airflow and reduced fuel injection pressures. The design and testing of an intrusive pylon geometry for scramjet combustor fueling is the subject of this research. Three pylon configurations are compared: a basic pylon, a ramp pylon, and an alternating wedge pylon. All three pylon configurations exhibit the …

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A Novel Method Characterizing The Impact Response Of Functionally Graded Plates, Reid A. Larson Sep 2008

A Novel Method Characterizing The Impact Response Of Functionally Graded Plates, Reid A. Larson

Theses and Dissertations

Functionally graded material (FGM) plates are advanced composites with properties that vary continuously through the thickness of the plate. Metal-ceramic FGM plates have been proposed for use in thermal protection systems where a metal-rich interior surface of the plate gradually transitions to a ceramic-rich exterior surface of the plate. The ability of FGMs to resist impact loads must be demonstrated before using them in high-temperature environments in service. This dissertation presents a novel technique by which the impact response of FGM plates is characterized for low-velocity, low- to medium-energy impact loads. An experiment was designed where strain histories in FGM …

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A Confidence Paradigm For Classification Systems, Nathan J. Leap Sep 2008

A Confidence Paradigm For Classification Systems, Nathan J. Leap

Theses and Dissertations

There is no universally accepted methodology to determine how much confidence one should have in a classifier output. This research proposes a framework to determine the level of confidence in an indication from a classifier system where the output is or can be transformed into a posterior probability estimate. This is a theoretical framework that attempts to unite the viewpoints of the classification system developer (or engineer) and the classification system user (or war-fighter). The paradigm is based on the assumptions that the system confidence acts like, or can be modeled as a value and that indication confidence can be …

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Creep Behavior Of Oxide/Oxide Composites With Monazite Fiber Coating At 1100°C In Air And In Steam Environments, Tufan Yeleser Sep 2008

Creep Behavior Of Oxide/Oxide Composites With Monazite Fiber Coating At 1100°C In Air And In Steam Environments, Tufan Yeleser

Theses and Dissertations

The creep behavior of six oxide-oxide ceramic-matrix composites (CMCs) was investigated at 1100 °C in laboratory air and in steam environments. The six CMC systems had an alumina ( Al2O3 ) matrix reinforced with NextelTM610 fibers. The CMC systems C1, C2 and C3 were reinforced with 10 uni-directional fiber layers in a symmetric cross-ply (0°/90°/0°/90°/0°)s orientation. In the case of composites C2 and C3, monazite (LaPO4) fiber coating was applied to the fibers. Composite C1 contained no fiber coating. In the case of composites C1 and C2, alumina matrix was infiltrated with monazite. The CMC systems …

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A Constraint Based Approach For Building Operationally Responsive Satellites, Mesut O. Kahraman Sep 2008

A Constraint Based Approach For Building Operationally Responsive Satellites, Mesut O. Kahraman

Theses and Dissertations

The Operational Responsive Space (ORS) program requires flexible and responsive satellites to meet user’s needs. Traditional satellite design methods are typically iterative processes that optimize individual components, subsystems, and ultimately the entire satellite. This study focuses on developing a new approach for creating Responsive Satellites (RS) from Plug-and-Play (PnP) components. The aim is to create an approach that quickly evaluates a wide variety of possible satellite configurations and identify the best configurations that meet the user’s needs and constraints. Satellite configurations are created by matching locations on the satellite structure with PnP components. Various constraints are derived from the user’s …

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Combat Identification Using Multiple Tuav Swarm, Younin Kang Sep 2008

Combat Identification Using Multiple Tuav Swarm, Younin Kang

Theses and Dissertations

In modern warfare, Tactical Unmanned Aerial Vehicles (TUAVs) are rapidly taking on a leading role in traditional and non-traditional ISR, to include Automatic Target Recognition (ATR). However, additional advancements in processors and sensors on TUAVs are still needed before they can be widely employed as a primary source for positive identification in the Combat Identification (CID) process. Cost is a driving factor for operating an ATR system using multiple TUAVs. The cost of high quality sensors appropriate for a single TUAV can be significantly higher than less sophisticated sensors suitable for deployment on a group, or swarm, of coordinated TUAVs. …

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Hall Thruster Plume Diagnostics Utilizing Microwave Interferometry, Vipul Sharma Sep 2008

Hall Thruster Plume Diagnostics Utilizing Microwave Interferometry, Vipul Sharma

Theses and Dissertations

The fatigue behavior of two woven SiC-SiNC ceramic matrix composites (CMCs) was investigated at 1300 °C in laboratory air and in steam. The first composite (C1) consists of a PIP SiNC matrix reinforced with Sylramic (Syl) fibers woven in a five-harness satin weave fabric and coated with a proprietary dual-layer interface. The second composite (C2) consists of a modified PIP SiNC matrix reinforced with Sylramic-iBN (Syl-iBN) fibers woven in a five-harness satin weave fabric and coated with a proprietary dual-layer interface. The tensile stress-strain behavior was investigated and the tensile properties measured at 1300°C. Tension-tension fatigue behavior was studied for …

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Range Precision Of Ladar Systems, Steven E. Johnson Sep 2008

Range Precision Of Ladar Systems, Steven E. Johnson

Theses and Dissertations

A key application of Laser Detection and Ranging (LADAR) systems is measurement of range to a target. Many modern LADAR systems are capable of transmitting laser pulses that are less than a few nanoseconds in duration. These short-duration pulses provide excellent range precision. However, randomness in the detected laser signals places limits on the precision. The goal of this dissertation is to quantify the range precision limits of LADAR systems. The randomness in the time between photon arrivals, which is called shot noise, is discussed in depth. System-dependent noise sources such as dark current and detector gain variation are considered. …

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Interoperability Measurement, Thomas C. Ford Aug 2008

Interoperability Measurement, Thomas C. Ford

Theses and Dissertations

This research presents an inaugural general method of measuring the collaborative and confrontational interoperability of a heterogeneous set of systems in the context of an operational process. The method is holistic, fundamental, flexible, and mathematical in nature and accommodates all types of systems and interoperations. The method relates the interoperability measurement to measures of operational effectiveness for confrontational operational processes. Extant leveling methods of describing interoperability are shown to be a special case of the more general method given in this research and the general interoperability measurement method is demonstrated through the presentation of coalition interoperability, suppression of enemy air …

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