Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons

Open Access. Powered by Scholars. Published by Universities.®

Theses and Dissertations

Discipline
Institution
Keyword
Publication Year

Articles 1 - 30 of 10266

Full-Text Articles in Engineering

Design Of Submicron Structured Guided-Mode-Resonance Near-Infrared Polarizer, Marzia Zaman May 2020

Design Of Submicron Structured Guided-Mode-Resonance Near-Infrared Polarizer, Marzia Zaman

Theses and Dissertations

The objective of this research is to design a larger submicron linear polarizer in the near-infrared wavelength range with a wide bandwidth which can be fabricated using the conventional thin-film microfabrication technology to reduce cost. For this purpose, a gold (Au) wire-grid transmission-type transverse-magnetic (TM) polarizer and a silicon (Si) wire-grid reflection-type TM polarizer, were designed using the guided-mode-resonance filter. The Au wire-grid TM polarizer of 700nm grating width and 1200nm grating period has 95% transmittance at 2400nm, more than 1000nm resonance peak bandwidth, and an extinction ratio (ER) of around 300 with a moderated level of sidebands. The 700nm ...


Experimental Study Of High-Speed Boats With Suspended Flaps For Reducing The Slamming Forces, Mohamed Raafat Amer May 2020

Experimental Study Of High-Speed Boats With Suspended Flaps For Reducing The Slamming Forces, Mohamed Raafat Amer

Theses and Dissertations

This thesis consists of two parts. In the first part a small-scale high-speed monohull boat was fitted with a suspended flap under the bottom. The author tested shock absorbers for this boat, and worked on data analysis from a few initial test runs. The boat tests were performed during a few hours in a single day and the data are far too scarce to draw any conclusions. The second part of the thesis concerns multi-body numerical analysis of a suspension boat that consists of an airborne centerhull and four suspended sponsons.

No simulations of boat dynamics in waves were performed ...


Polyester Polymer Concrete For Bridge Deck Overlays, Robert James Stevens Apr 2020

Polyester Polymer Concrete For Bridge Deck Overlays, Robert James Stevens

Theses and Dissertations

The objectives of this research were to 1) compile a synthesis of information about polyester polymer concrete (PPC) from the literature; 2) conduct a scanning tour to observe PPC construction, inspect in-service PPC overlays, and discuss topics related to PPC; 3) revise the existing Utah Department of Transportation (UDOT) PPC specification; 4) document a PPC field demonstration project; and 5) perform laboratory characterization of the material properties of field-mixed PPC. The scope of the research included a scanning tour, field testing, and laboratory experimentation. The objectives of the scanning tour included observation of a PPC overlay placement, inspection of existing ...


Isogeometric Shell Analysis: Multi-Patch Coupling And Overcoming Locking, Zhihui Zou Apr 2020

Isogeometric Shell Analysis: Multi-Patch Coupling And Overcoming Locking, Zhihui Zou

Theses and Dissertations

The fundamental advantages of applying Isogeometric Analysis (IGA) to shell analysis have been extensively demonstrated across a wide range of problems and formulations. However, a phenomenon called numerical locking is still a major challenge in IGA shell analysis, which can lead to dramatically deteriorated analysis accuracy. Additionally, for complex thin-walled structures, a simple and robust coupling technique is desired to sew together models composed of multiple patches. This dissertation focuses on addressing these challenges of IGA shell analysis. First, an isogeometric dual mortar method is developed for multi-patch coupling. This method is based on Be ?zier extraction and projection and ...


An Open-Source Web-Application For Regional Analysis Of Grace Groundwater Data And Engaging Stakeholders In Groundwater Management, Travis Clinton Mcstraw Apr 2020

An Open-Source Web-Application For Regional Analysis Of Grace Groundwater Data And Engaging Stakeholders In Groundwater Management, Travis Clinton Mcstraw

Theses and Dissertations

Since 2002, NASA's GRACE Satellite mission has allowed scientists of various disciplines to analyze and map the changes in Earth's total water storage on a global scale. Although the raw data is available to the public, the process of viewing, manipulating, and analyzing the GRACE data can be difficult for those without strong technological backgrounds in programming or geospatial software. This is particularly true for water managers in developing countries, where GRACE data could be a valuable asset for sustainable water resource management. To address this problem, I have a developed a utility for subsetting GRACE data to ...


Bacteria In Blood: Optimized Recovery Of Bacterial Dna For Rapid Identification, Ryan Wood Mar 2020

Bacteria In Blood: Optimized Recovery Of Bacterial Dna For Rapid Identification, Ryan Wood

Theses and Dissertations

Blood stream infections are challenging infections to rapidly diagnose. The current clinical diagnostic methods for blood stream infections require culturing the blood sample prior to identifying the bacteria and any resistance the bacteria may contain. Removing the culturing step from the bacterial identification process of a blood stream infection provides a significant reduction in the processing time. However, eliminating the culturing step shifts the difficulty from processing time to concentration, since clinical concentration levels can be as low as 10 CFU/mL in blood. This dissertation developed and evaluated many aspects of the process required to identify bacteria from a ...


One-Dimensional Multi-Frame Blind Deconvolution Using Astronomical Data For Spatially Separable Objects, Marc R. Brown Mar 2020

One-Dimensional Multi-Frame Blind Deconvolution Using Astronomical Data For Spatially Separable Objects, Marc R. Brown

Theses and Dissertations

Blind deconvolution is used to complete missions to detect adversary assets in space and to defend the nation's assets. A new algorithm was developed to perform blind deconvolution for objects that are spatially separable using multiple frames of data. This new one-dimensional approach uses the expectation-maximization algorithm to blindly deconvolve spatially separable objects. This object separation reduces the size of the object matrix from an NxN matrix to two singular vectors of length N. With limited knowledge of the object and point spread function the one-dimensional algorithm successfully deconvolved the objects in both simulated and laboratory data.


Signal Quality Monitoring Of Gnss Signals Using A Chip Shape Deformation Metric, Nicholas C. Echeverry Mar 2020

Signal Quality Monitoring Of Gnss Signals Using A Chip Shape Deformation Metric, Nicholas C. Echeverry

Theses and Dissertations

The Global Navigation Satellite System continues to become deeply em-bedded within modern civilization, and is depended on for confident, accurate navigation information. High precision position and timing accuracy is typically achieved using differential processing, however these systems provide limited compensation for distortions caused by multi-path or faulty satellite hardware. Signal Quality Monitoring (SQM) aims to provide confidence in a receivers Position, Navigation, and Timing solution and to offer timely warnings in the event that signal conditions degrade to unsafe levels. The methods presented in this document focus on implementing effective SQM using low-cost Commercial Off-the-Shelf equipment, a Software Defined Radio ...


Flight Characteristic Verification Of The Variable Camber Compliant Wing, Sharee B. Acosta Mar 2020

Flight Characteristic Verification Of The Variable Camber Compliant Wing, Sharee B. Acosta

Theses and Dissertations

Morphing wing technology gives aircraft the ability to change wing shape to control the aircraft and flight performance characteristics. AFIT, AFRL and USU Aero Lab have collaborated to design and test a variable camber compliant wing (VCCW) on a small unmanned aerial vehicle (UAV). Flight tests demonstrated the wing performance and provided data to refine a VCCW flight simulator. Work was completed with the USU AeroLab-generated MachUp and the actual flight data to improve the simulator to provide results close to those of the actual flight test. The research provides a tool to reduce time and cost for future flight ...


Developing A Serious Game To Explore Joint All Domain Command And Control, Nathaniel W. Flack Mar 2020

Developing A Serious Game To Explore Joint All Domain Command And Control, Nathaniel W. Flack

Theses and Dissertations

Changes in the geopolitical landscape and increasing technological complexity have prompted the U.S. Military to coin Multi-Domain Operations (MDO) and Joint All-Domain Command and Control as terms to describe an over-arching strategy that frames the complexity of warfare across both traditional and emerging warfighting domains. Teaching new and advanced concepts associated with these terms requires both innovation as well as distinct education and training tools in order to realize the cultural change advocated by senior military leaders. BSN, a Collectible Card Game, was developed to teach concepts integral to MDO and initiate discussion on military strategy.


Dynamic Micromechanical Fabry-Perot Cavity Sensors Fabricated By Multiphoton Absorption Onto Optical Fiber Tips, Jeremiah C. Williams Mar 2020

Dynamic Micromechanical Fabry-Perot Cavity Sensors Fabricated By Multiphoton Absorption Onto Optical Fiber Tips, Jeremiah C. Williams

Theses and Dissertations

This research leveraged two-photon polymerization microfabrication to integrate dynamic mechanical components with Fabry-Perot resonators onto the ends of low-loss optical fibers to prototype 3 micro-optic devices. The first device featured a multi-positional mirror that enabled thin-film deposition onto cavities of any length with mirrors of significant curvature, for refractive index sensing. The second device combined an FP cavity with a spring body featuring easily scalable stiffness for pressure sensing. The third device presented a high-speed rotating micro-anemometer for measuring a wide range of gas flows. All devices represent a significant reduction in size and weight over commercially available devices.


Object Detection With Deep Learning To Accelerate Pose Estimation For Automated Aerial Refueling, Andrew T. Lee Mar 2020

Object Detection With Deep Learning To Accelerate Pose Estimation For Automated Aerial Refueling, Andrew T. Lee

Theses and Dissertations

Remotely piloted aircraft (RPAs) cannot currently refuel during flight because the latency between the pilot and the aircraft is too great to safely perform aerial refueling maneuvers. However, an AAR system removes this limitation by allowing the tanker to directly control the RP A. The tanker quickly finding the relative position and orientation (pose) of the approaching aircraft is the first step to create an AAR system. Previous work at AFIT demonstrates that stereo camera systems provide robust pose estimation capability. This thesis first extends that work by examining the effects of the cameras' resolution on the quality of pose ...


A Comparative Evaluation Of The Detection And Tracking Capability Between Novel Event-Based And Conventional Frame-Based Sensors, James P. Boettiger Mar 2020

A Comparative Evaluation Of The Detection And Tracking Capability Between Novel Event-Based And Conventional Frame-Based Sensors, James P. Boettiger

Theses and Dissertations

Traditional frame-based technology continues to suffer from motion blur, low dynamic range, speed limitations and high data storage requirements. Event-based sensors offer a potential solution to these challenges. This research centers around a comparative assessment of frame and event-based object detection and tracking. A basic frame-based algorithm is used to compare against two different event-based algorithms. First event-based pseudo-frames were parsed through standard frame-based algorithms and secondly, target tracks were constructed directly from filtered events. The findings show there is significant value in pursuing the technology further.


Sortie-Based Aircraft Component Demand Rate To Predict Requirements, Thomas R. O'Neal Mar 2020

Sortie-Based Aircraft Component Demand Rate To Predict Requirements, Thomas R. O'Neal

Theses and Dissertations

Weapon System Sustainment (WSS) costs are growing at an increasing rate despite the vast efforts to reduce them. Researchers have attributed much of the cost increase to inaccurate demand forecasts for weapon system spare parts. In 2011, the forecast to sustain all United States Air Force (USAF) aircraft was 19% accurate and WSS costs per year have continuously increased. The purpose of this study is to explore a parsimonious change to aircraft component forecasting to reduce costly forecast error. This study substitutes flying hours with sorties for the purpose of demand forecasting. Many F-16 and B-52 spare parts are evaluated ...


Implications And Limitations Of Securing An In Niband Network, Lucas E. Mireles Mar 2020

Implications And Limitations Of Securing An In Niband Network, Lucas E. Mireles

Theses and Dissertations

The InfiniBand Architecture is one of the leading network interconnects used in high performance computing, delivering very high bandwidth and low latency. As the popularity of InfiniBand increases, the possibility for new InfiniBand applications arise outside the domain of high performance computing, thereby creating the opportunity for new security risks. In this work, new security questions are considered and addressed. The study demonstrates that many common traffic analyzing tools cannot monitor or capture InfiniBand traffic transmitted between two hosts. Due to the kernel bypass nature of InfiniBand, many host-based network security systems cannot be executed on InfiniBand applications. Those that ...


Multi-Channel Security Through Data Fragmentation, Micah J. Hayden Mar 2020

Multi-Channel Security Through Data Fragmentation, Micah J. Hayden

Theses and Dissertations

This thesis presents a novel security system developed for a multi-channel communication architecture, which achieves security by distributing the message and its associated message authentication code across the available channels at the bit level, to support systems that require protection from confidentiality and integrity attacks without relying solely on traditional encryption. One contribution of the work is to establish some helpful terminology, present a basic theory for multi-channel communications, describe the services provided by an optimal system, and then implement a proof of concept system to demonstrate the concept's validity. This proof of concept, focused on the splitting and ...


Ground Weather Radar Signal Characterization Through Application Of Convolutional Neural Networks, Stephen M. Lee Mar 2020

Ground Weather Radar Signal Characterization Through Application Of Convolutional Neural Networks, Stephen M. Lee

Theses and Dissertations

The 45th Weather Squadron supports the space launch efforts out of the Kennedy Space Center and Cape Canaveral Air Force Station for the Department of Defense, NASA, and commercial customers through weather assessments. Their assessment of the Lightning Launch Commit Criteria (LLCC) for avoidance of natural and rocket triggered lightning to launch vehicles is critical in approving space shuttle and rocket launches. The LLCC includes standards for cloud formations, which requires proper cloud identification and characterization methods. Accurate reflectivity measurements for ground weather radar are important to meet the LLCC for rocket triggered lightning. Current linear interpolation methods for ground ...


Wireless Sensor Network Optimization For Radio Tomographic Imaging, Grant T. Nafziger Mar 2020

Wireless Sensor Network Optimization For Radio Tomographic Imaging, Grant T. Nafziger

Theses and Dissertations

Radio tomographic imaging (RTI) is a form of device-free, passive localization (DFPL) that uses a wireless sensor network (WSN) typically made up of affordable, low-power transceivers. The intent for RTI is to have the ability to monitor a given area, localizing and tracking obstructions within. The specific advantages rendered by RTI include the ability to provide imaging, localization, and tracking where other well developed methods like optical surveillance fall short. RTI can function through optical obstructions such as smoke and even physical obstructions like walls. This provides a tool that is particularly valuable for tactical operations like emergency response and ...


Sliver: Simulation-Based Logic Bomb Identification/Verification For Unmanned Aerial Vehicles, Jake M. Magness Mar 2020

Sliver: Simulation-Based Logic Bomb Identification/Verification For Unmanned Aerial Vehicles, Jake M. Magness

Theses and Dissertations

This research introduces SLIVer, a Simulation-based Logic Bomb Identification/Verification methodology, for finding logic bombs hidden within Unmanned Aerial Vehicle (UAV) autopilot code without having access to the device source code. Effectiveness is demonstrated by executing a series of test missions within a high-fidelity software-in-the-loop (SITL) simulator. In the event that a logic bomb is not detected, this methodology defines safe operating areas for UAVs to ensure to a high degree of confidence the UAV operates normally on the defined flight plan. SLIVer uses preplanned flight paths as the baseline input space, greatly reducing the input space that must be ...


Multivariate Analysis Of Human Performance Strong Lab Data, Kayla N. Tinucci Mar 2020

Multivariate Analysis Of Human Performance Strong Lab Data, Kayla N. Tinucci

Theses and Dissertations

This study uses multivariate analysis methods to find relationships between nutrition and wellness and nutrition and performance. The nutrition, daily wellness, and weight and bodyfat data are from a study performed by the STRONG lab in the 711th Human Performance Wing. Electronically collected nutrition data along with survey data for 19 individuals over a 12-week study period are examined with a focus on health, fitness, and nutrition. Factor analysis and linear regression are performed and inferences are drawn regarding what effects calories and macronutrient intake have on subjects perceived wellness, weight, and body fat percentage. These insights are discussed in ...


Comparison Of Visual Simultaneous Localization And Mapping Methods For Fixed-Wing Aircraft Using Slambench2, Patrick R. Latcham Mar 2020

Comparison Of Visual Simultaneous Localization And Mapping Methods For Fixed-Wing Aircraft Using Slambench2, Patrick R. Latcham

Theses and Dissertations

Visual Simultaneous Localization and Mapping (VSLAM) algorithms have evolved rapidly in the last few years, however there has been little research evaluating current algorithm's effectiveness and limitations when applied to tracking the position of a fixed-wing aerial vehicle. This research looks to evaluate current monocular VSLAM algorithms' performance on aerial vehicle datasets using the SLAMBench2 benchmarking suite. The algorithms tested are MonoSLAM, PTAM, OKVIS, LSDSLAM, ORB-SLAM2, and SVO, all of which are built into the SLAMBench2 software. The algorithms' performance is evaluated using simulated datasets generated in the AftrBurner Engine. The datasets were designed to test the quality of ...


Mismatched Filter Effects On Synthetic Aperture Radar Image Quality Metrics, Jerrod M. Kempf Mar 2020

Mismatched Filter Effects On Synthetic Aperture Radar Image Quality Metrics, Jerrod M. Kempf

Theses and Dissertations

Detection of targets across a wide dynamic range is an enduring challenge in radar. This work formulates a modified least-squares mismatched filter that greatly reduces these sidelobes in order to enable the detection of small radar cross section targets in the presence of considerably larger scatterers, increasing the dynamic range. Unlike previous mismatched filters, the proposed filter is applicable to noisy, oversampled signals with no requirements on signal structure. Range profiles and images are presented to demonstrate the superior sidelobe suppression of the modified least-squares mismatched filter in comparison to the commonly employed matched filter. Various weighting vectors are introduced ...


A Metamodel Recommendation System Using Meta-Learning, Megan K. Woods Mar 2020

A Metamodel Recommendation System Using Meta-Learning, Megan K. Woods

Theses and Dissertations

The importance and value of statistical predictions increase as data grows in availability and quantity. Metamodels, or surrogate models, provide the ability to rapidly approximate and predict information. However, selection of the appropriate metamodel for a given dataset is often arduous, and the choice of the wrong metamodel could lead to considerably inaccurate results. This research proposes and tests the framework for a metamodel recommendation system. The implementation allows for virtually any dataset and preprocesses data, calculates meta-features, evaluates the performance of various metamodels, and learns how the data behaves via meta-learning, thus preparing and bettering itself for future recommendations ...


Focused Beam System Biaxial Material Characterization, Nicholas A. O'Gorman Mar 2020

Focused Beam System Biaxial Material Characterization, Nicholas A. O'Gorman

Theses and Dissertations

Electromagnetic material characterization is the process of determining the constitutive parameters (complex permittivity and permeability) of given a sample. Due to the large number of unknowns involved, multiple unique measurements are required for material property extraction. Many measurement methods, such as waveguides and striplines, possess a rigid internal structure that the sample being measured must adhere to. This rigidity limits these methods to samples that fit within the device and inhibits oblique sample orientations, limiting the number of independent measurements that can be obtained. A focus beam system, due to being an open system with greater freedom in sample size ...


Database Analysis To Improve U.S. Transportation Command Forecasting Processes, Maxwell C. Thompson Mar 2020

Database Analysis To Improve U.S. Transportation Command Forecasting Processes, Maxwell C. Thompson

Theses and Dissertations

The United States Transportation Command (USTRANSCOM) facilitates air, land, and sea transportation for the DOD. On a periodic basis, a myriad of different agencies within USTRANSCOM project future workload to facilitate resource planning, budgeting, and reimbursable rate identification. Within USTRANSCOM, there are a variety of databases and metrics utilized for workload forecasts; neither a standard nor a preferred technique is prescribed. Currently, USTRANSCOM faces challenges in producing accurate workload forecasts [1]. These challenges can lead to unreliable budget requests and, ultimately, hinder the effectiveness and efficiency of USTRANSCOM [1]. For the purpose of routine aircraft movements of cargo and personnel ...


Characterization And Sensitivity Analysis Of 6 Meter Cassegrain Antenna, James L. Harris Mar 2020

Characterization And Sensitivity Analysis Of 6 Meter Cassegrain Antenna, James L. Harris

Theses and Dissertations

This paper will characterize a 6 meter in diameter cassegrain antenna. The cassegrain antenna is a special form of a dual reflector antenna which uses a main reflector following a parabolic curve and a sub reflector which follows a hyperbolic curve. Cassegrain style antennas have multiple parameters which can be tuned to achieve specific design goals. Performing a sensitivity analysis will establish relationships between design parameters, directivity, side lobe levels, and effects of strut geometry. The initial design parameters will be assumed based on typical values. Results from the sensitivity analysis will be used to provide a performance band for ...


A Non-Destructive Evaluation Application Using Software Defined Radios And Bandwidth Expansion, Nicholas J. O'Brien Mar 2020

A Non-Destructive Evaluation Application Using Software Defined Radios And Bandwidth Expansion, Nicholas J. O'Brien

Theses and Dissertations

The development of low-complexity, lightweight and low-cost Non-Destructive Evaluation (NDE) equipment for microwave device testing is desirable from a maintenance efficiency and operational availability perspective. Current NDE equipment tends to be custom-designed, cumbersome and expensive. Software Defined Radio (SDR) technology, and a bandwidth expansion technique that exploits a priori transmit signal knowledge and auto-correlation provides a solution. This research investigated the reconstruction of simultaneous SDR receiver instantaneous bandwidth (sub-band) collections using single, dual and multiple SDR receivers. The adjacent sub-bands, collectively spanning a transmit signal bandwidth were auto-correlated with a replica transmit signal to restore frequency and phase offsets. The ...


Resilient Aircraft Sustainment: Quantifying Resilience Through Asset And Capacity Allocation, Zachary B. Shannon Mar 2020

Resilient Aircraft Sustainment: Quantifying Resilience Through Asset And Capacity Allocation, Zachary B. Shannon

Theses and Dissertations

Decision makers lack a clear, generalizable method to quantify how additional investment in inventory and capacity equates to additional levels of resilience. This research facilitates a deeper understanding of the intricacies and complex interconnectedness of organizational supply chains by monetarily quantifying changes in network resilience. The developed Area under the Curve metric (AUC) is used to quantify the level of demand that each asset allocation can meet during a disruptive event. Due to its applicability across multiple domains, the USAF F-16 repair network in the Pacific theater (PACAF) is modeled utilizing discrete event simulation and used as the illustrating example ...


Lightning Prediction For Space Launch Using Machine Learning Based Off Of Electric Field Mills And Lightning Detection And Ranging Data, Anson Cheng Mar 2020

Lightning Prediction For Space Launch Using Machine Learning Based Off Of Electric Field Mills And Lightning Detection And Ranging Data, Anson Cheng

Theses and Dissertations

Kennedy Space Center and Cape Canaveral Air Station, FL, where the Air Force conducts space launches, are in an area of frequent lightning strikes, which is main obstacle in meeting launch goals. The 45th Weather Squadron (45th WS) ensures that any weather safety requirements are met during pre-launch and actual space launch. Using only summer months from three years’ worth of lightning detection and ranging (LDAR) and electric field mill (EFM) data from KSC, several feedforward neural networks are constructed. Separate models are built for each EFM and trained by adjusting parameters to forecast lightning 30 minutes out in the ...


Characterization Of Reactive Ion Etch Chemistries Using Direct Write Lithography, Dylan T. Martin-Abood Mar 2020

Characterization Of Reactive Ion Etch Chemistries Using Direct Write Lithography, Dylan T. Martin-Abood

Theses and Dissertations

The DoD requires a variety of COTS and number of custom microelectronics to provide important functionality to critical military systems. Photolithography and DRIE are two techniques commonly used in the development of deep anisotropic features for the fabrication and modification of microelectronics and MEMS. However, standard photolithography techniques are ineffective for unique substrate geometries and DRIE processes require a chemical passivation step only applicable to Si substrates. This work confirmed the capability of RIE using DWL to perform deep, highly selective, anisotropic etching on elevated, non-circular substrates.