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Articles 1 - 30 of 108
Full-Text Articles in Engineering
Multiple Agent Target Tracking In Gps-Denied Environments, Skyler Tolman
Multiple Agent Target Tracking In Gps-Denied Environments, Skyler Tolman
Theses and Dissertations
Unmanned aerial systems (UAS) are effective for surveillance and monitoring, but struggle with persistent, long-term tracking, especially without GPS, due to limited flight time. Persistent tracking can be accomplished using multiple vehicles if one vehicle can effectively hand off the tracking information to another replacement vehicle. This work presents a solution to the moving-target handoff problem in the absence of GPS. The proposed solution (a) a nonlinear complementary filter for self-pose estimation using only an IMU, (b) a particle filter for relative pose estimation between UAS using a relative range (c) visual target tracking using a gimballed camera when the …
Analysis Of Applied Modifications To A Cone Penetration Test-Based Lateral Spread Displacement Prediction Model, Alexander Edward Corob
Analysis Of Applied Modifications To A Cone Penetration Test-Based Lateral Spread Displacement Prediction Model, Alexander Edward Corob
Theses and Dissertations
This study set out to examine the effectiveness and reliability of six modifications to the Zhang et al. (2004) CPT-based lateral spread model. A regression analysis, distribution charts, and a discriminant analysis are performed to determine how effective the modifications are on the model. From the comparisons and statistical analysis performed in this study, application of these modifications reduces over-predictions from strain-based prediction methods. Unfortunately, the tendency to under-predict displacements on average is also increased.
Bending Behavior Of Concrete Beams With Fiber/Epoxy Composite Rebar, Kolten Dewayne Rice
Bending Behavior Of Concrete Beams With Fiber/Epoxy Composite Rebar, Kolten Dewayne Rice
Theses and Dissertations
This research explores the use of carbon/epoxy and fiberglass/epoxy fiber-reinforced polymer (FRP) composite rebar manufactured on a three-dimensional braiding machine for use as reinforcement in concrete beams under four-point bending loads. Multiple tows of prepreg composite fibers were pulled to form a unidirectional core. The core was consolidated with spirally wound Kevlar fibers which were designed to also act as ribs to increase pullout strength. The rebar was cured at 121â—¦C (250â—¦F) in an inline oven while keeping tension on the fibers. Five configurations of reinforcing bars were used in this study as reinforcement in concrete beam specimens: carbon/epoxy rebar …
Characterization And Modeling Of The Martensite Transformation In Advanced High-Strength Steels, Stephen Roy Cluff
Characterization And Modeling Of The Martensite Transformation In Advanced High-Strength Steels, Stephen Roy Cluff
Theses and Dissertations
Multiple studies on the microstructures of advanced high-strength steels are presented here that seek to add to the already substantial body of knowledge on martensite in steel. These studies seek to gain additional insight into the role that the martensite transformation has on the observed mechanical properties of modern steels. Crystallographic Reconstruction of Parent Austenite Twin Boundaries in a Lath Martensitic Steel The study of post-transformation microstructures and their properties can be greatly enhanced by studying their dependence on the grain boundary content of parent microstructures. Recent work has extended the crystallographic reconstruction of parent austenite in steels to include …
Machine Learning On Acoustic Signals Applied To High-Speed Bridge Deck Defect Detection, Yao Chou
Machine Learning On Acoustic Signals Applied To High-Speed Bridge Deck Defect Detection, Yao Chou
Theses and Dissertations
Machine learning techniques are being applied to many data-intensive problems because they can accurately provide classification of complex data using appropriate training. Often, the performance of machine learning can exceed the performance of traditional techniques because machine learning can take advantage of higher dimensionality than traditional algorithms. In this work, acoustic data sets taken using a rapid scanning technique on concrete bridge decks provided an opportunity to both apply machine learning algorithms to improve detection performance and also to investigate the ways that training of neural networks can be aided by data augmentation approaches. Early detection and repair can enhance …
An Exploration Of Neural Networks In Enhanced Resolution Remote Sensing Products, Jordan Paul Brown
An Exploration Of Neural Networks In Enhanced Resolution Remote Sensing Products, Jordan Paul Brown
Theses and Dissertations
Scatterometry and radiometry are used to obtain measurements of Earth properties with extensive spatial coverage at daily or near-daily temporal resolution. Their measurements are used in many climate studies and weather applications, such as iceberg tracking, ocean wind estimation, and volumetric soil moisture measurements. The spatial resolution of these data products ranges from a few kilometers to tens of kilometers. Techniques to enhance the spatial resolution of these products help reveal finer scale features, but come at the cost of increased noise. This thesis explores the application of neural networks as a possible method to handle the noise and uncertainty …
Near-Coastal Ultrahigh Resolution Scatterometer Winds, Nolan Lawrence Hutchings
Near-Coastal Ultrahigh Resolution Scatterometer Winds, Nolan Lawrence Hutchings
Theses and Dissertations
RapidScat 2.5 km ultrahigh resolution (UHR) wind estimation is introduced and validated it in near-coastal regions. In addition, this thesis applies direction interval retrieval techniques and develops a new wind processing method to enhance the performance of RapidScat UHR wind estimation in the nadir region. The new algorithm is validated with L2B wind estimates, Numerical Weather Prediction (NWP) wind products, and buoy measurements. The wind processing improvements produce more spatially consistent UHR winds that compare well with the wind products mentioned above. Hawaii regional climate model (HRCM), QuikSCAT, and ASCAT wind estimates are compared in the lee of the Big …
Vertical Electrical Impedance Measurements Of Concrete Bridge Decks, Jared Scott Baxter
Vertical Electrical Impedance Measurements Of Concrete Bridge Decks, Jared Scott Baxter
Theses and Dissertations
This research focuses on the creation, validation, automation, and deployment of a nondestructive vertical electrical impedance (VEI) bridge deck assessment apparatus. A multichannel impedance analyzer with a moving platform is developed that can assess the deterioration state of a bridge deck without stationary traffic control. The multichannel apparatus is capable of taking over 500 impedance samples a second and can scan a bridge deck over 500 times faster than more traditional techniques. This research also shows VEI measurements are inversely proportional to the diffusivity of ions through concrete and that an impedance measurement frequency of 25 kHz is the most …
Scatterometer Cross Calibration Using Volume Scattering Models For Amazon Rainforest Canopies, Evan Neil Chrisney
Scatterometer Cross Calibration Using Volume Scattering Models For Amazon Rainforest Canopies, Evan Neil Chrisney
Theses and Dissertations
Spaceborne scatterometers have measured the normalized radar cross section (RCS) of the earth's surface for several decades. Two frequencies, C- and Ku-band, have been used in designing scatterometers, such as with the Ku-band NASA Scatterometer (NSCAT) and the C-band Advanced Scatterometer (ASCAT). The scatterometer data record between C- and Ku-band has been disjoint for several decades due to the difficulties in cross calibration of sensors that operate at different frequencies and incidence angles. A model for volume scattering over the Amazon rainforest canopy that includes both the incidence angle and frequency dependence is developed to overcome this challenge in cross …
Trajectory Optimization And Design For A Large Number Of Unmanned Aerial Vehicles, Jenna Elisabeth Newcomb
Trajectory Optimization And Design For A Large Number Of Unmanned Aerial Vehicles, Jenna Elisabeth Newcomb
Theses and Dissertations
An unmanned aerial vehicle (UAV) swarm allows for a more time-efficient method of searching a specified area than a single UAV or piloted plane. There are a variety of factors that affect how well an area is surveyed. We specifically analyzed the effect both vehicle properties and communication had on the swarm search performance. We used non-dimensionalization so the results can be applied to any domain size with any type of vehicle. We found that endurance was the most important factor. Vehicles with good endurance sensed approximately 90% to 100% of the grid, even when other properties were lacking. If …
Improving Hydroshare And Web Application Interoperability Through Integrated Gis And His Data Services, Kenneth Jack Lippold
Improving Hydroshare And Web Application Interoperability Through Integrated Gis And His Data Services, Kenneth Jack Lippold
Theses and Dissertations
HydroShare is a collaborative online system being developed by the Consortium of Universities for the Advancement of Hydrologic Science Inc. (CUAHSI) with the goal of facilitating the dissemination, visualization, and publishing of hydrologic data and models. External web applications serve a key role in extending HydroShare's capabilities, so robust application programming interfaces (APIs) are a vital component of HydroShare's architecture. Hydrologic data stored on HydroShare are defined by a data type, and much of these data are either geospatial or time series data. Although HydroShare's API provides ways to upload and download files, as well as access certain metadata, it …
Enabling Compact Devices Through Origami And Developable Mechanisms, Jacob Ryan Greenwood
Enabling Compact Devices Through Origami And Developable Mechanisms, Jacob Ryan Greenwood
Theses and Dissertations
This thesis provides resources that enable the design of novel and compact mechanical devices by providing terminology, engineering models, and design methods in the fields of developable mechanisms and origami-based engineering.The first part of this work presents engineering models to aid in the design of cylindrical developable mechanisms. These models take into account the added spatial restrictions imposed by the developable surface. Equations are provided for the kinematic analysis of cylindrical developable mechanisms. A new classification for developable mechanisms is also presented (intramobile, extramobile, and transmobile) and two graphical methods are provided for determining this classification for single-DOF planar cylindrical …
A Soft-Error Reliability Testing Platform For Fpga-Based Network Systems, Hayden Cole Rowberry
A Soft-Error Reliability Testing Platform For Fpga-Based Network Systems, Hayden Cole Rowberry
Theses and Dissertations
FPGAs are frequently used in network systems to provide the performance and flexibility that is required of modern computer networks while allowing network vendors to bring products to market quickly. Like all electronic devices, FPGAs are vulnerable to ionizing radiation which can cause applications operating on an FPGA to fail. These low-level failures can have a wide range of negative effects on the performance of a network system. As computer networks play a larger role in modern society, it becomes increasingly important that these soft errors are addressed in the design of network systems.This work presents a framework for testing …
Maverick: A Stand-Alone Cad Flow For Partially Reconfigurable Fpga Modules, Dallon Godfrey Glick
Maverick: A Stand-Alone Cad Flow For Partially Reconfigurable Fpga Modules, Dallon Godfrey Glick
Theses and Dissertations
Circuit designs for field-programmable gate arrays (FPGAs) are typically compiled by FPGA vendor tools, such as Xilinx's Vivado Design Suite. In recent years, partial reconfiguration (PR) has emerged as a popular technique that allows portions of an FPGA to be dynamically reconfigured after the complete device has been configured with an initial bitstream. However, the nature of current FPGA vendor tools limits further innovation and possible usage models of PR.This thesis presents Maverick, an open-source proof-of-concept computer-aided design (CAD) flow for generating reconfigurable modules (RMs) which target PR regions in FPGA designs. Maverick builds upon existing open source tools (Yosys, …
Development Of A Gpu-Based Real-Time Interference Mitigating Beamformer For Radio Astronomy, Jeffrey M. Nybo
Development Of A Gpu-Based Real-Time Interference Mitigating Beamformer For Radio Astronomy, Jeffrey M. Nybo
Theses and Dissertations
Radio frequency interference (RFI) mitigation enables radio astronomical observation in frequency bands that are shared with many modern satellite and ground based devices by filtering out the interference in corrupted bands. The present work documents the development of a beamformer (spatial filter) equipped with RFI mitigation capabilities. The beamformer is intended for systems with antenna arrays designed for large bandwidths. Because array data post processing on large bandwidths would require massive memory space beyond feasible limits, there is a need for a RFI mitigation system capable of doing processing on the data as it arrives in real-time; storing only a …
Investigation Of Electrocoating Mechanisms, Tyler James Marlar
Investigation Of Electrocoating Mechanisms, Tyler James Marlar
Theses and Dissertations
The objective of this work is to advance the mechanistic understanding of cathodic electrocoating. These efforts are focused on the initial processes responsible for deposition, which are examined through direct experimentation and simulation. Electrocoating is a global industrial process providing a corrosive resistant base paint to automobile bodies. Presently, empirical models are used to model coating thickness; these models tend to overpredict deposition in occluded areas. Convection is implemented to study the behavior of adhered surface H2 bubbles on the substrate surfaces. The impact of surface H2 bubbles and early e-coat deposition on the local current density is studied using …
Exploring The Efficiency Of Software-Defined Radios In 3d Heat Mapping, Andrew Scott Thomas
Exploring The Efficiency Of Software-Defined Radios In 3d Heat Mapping, Andrew Scott Thomas
Theses and Dissertations
A common method of connecting to the internet is a wireless network. These networks can be monitored to discover the area of their coverage, but commercial receivers don't always provide the most accurate results. A software-defined radio was programmed to sniff wireless signals and tested against a commercial receiver and the results were compared. The results suggest that the software-defined radio performs at least as well as the commercial receiver in distance measurements and significantly better in samples taken per minute. It was determined that the software-defined radio is a viable replacement for a commercial receiver in 3D heat mapping.
A New Qpcr Assay To Detect Geosmin-Producing Cyanobacteria, Shane Brian Davis
A New Qpcr Assay To Detect Geosmin-Producing Cyanobacteria, Shane Brian Davis
Theses and Dissertations
Taste-and-odor (T&O) compounds are frequently produced by cyanobacterial blooms in bodies of water. Geosmin, perhaps the most common T&O compound produced by these blooms, is not effectively removed by conventional water treatment processes and frequently causes the tap water to have an off flavor. Although geosmin is not harmful when ingested, it damages the consumers' confidence in the cleanliness of their water. There are treatment options for geosmin removal, but the most common methods are often not implemented until complaints are made by consumers.There has been an increasing amount of research on the use of polymerase chain reaction (PCR)-based methods …
Variance Reduction In Wind Farm Layout Optimization, Bertelsen Gagakuma
Variance Reduction In Wind Farm Layout Optimization, Bertelsen Gagakuma
Theses and Dissertations
As demand for wind power continues to grow, it is becoming increasingly important to minimize the risk, characterized by the variance, that is associated with long-term power forecasts. This thesis investigated variance reduction in power forecasts from wind farm layout optimization.The problem was formulated as a multi-objective optimization one of maximizing mean-plant-power and minimizing variance. The ε−constraint method was used to solve the bi-objectiveproblem in a two-step optimization framework where two sequential optimizations are performed. The first is maximizing mean wind farm power alone and the second, minimizing variance with a constraint on the mean power which is the value …
Splice Performance Of #6 Reinforcing Bars In Masonry With Self-Consolidating Grout, Annie Ruth Nielson
Splice Performance Of #6 Reinforcing Bars In Masonry With Self-Consolidating Grout, Annie Ruth Nielson
Theses and Dissertations
Reinforced masonry grouted using self-consolidating grout (SCG) is a relatively new and economically competitive option for construction, providing advantages such as reduced construction time, decreased noise and vibration, and reliable consolidation. However, SCG has different properties than conventional grout and its performance should be verified using current governing code requirements. The purpose of this research program was to determine the development length of spliced reinforcing bars in masonry grouted with SCG.Twelve masonry panels, four courses high and two and a half blocks wide, were constructed using 8-inch concrete masonry units, each with two pairs of vertically spliced #6 reinforcing bars. …
Design Optimization For A Compliant,Continuum-Joint, Quadruped Robot, Vallan Gray Sherrod
Design Optimization For A Compliant,Continuum-Joint, Quadruped Robot, Vallan Gray Sherrod
Theses and Dissertations
Legged robots have the potential to cover terrain not accessible to wheel-based robots and vehicles. This makes them better suited to perform tasks, such as search and rescue, in real-world unstructured environments. Pneumatically-actuated, compliant robots are also more suited than their rigid counterparts to work in real-world unstructured environments with humans where unintentional contact may occur. This thesis seeks to combine the benefits of these two type of robots by implementing design methods to aid in the design choice of a 16 degree of freedom (DoF) compliant, continuum-joint quadruped. This work focuses on the design optimization, especially the definition of …
Characterization Of Local Void Content In Carbon Fiber Reinforced Plastic Parts Utilizing Observation Of In Situ Fluorescent Dye Within Epoxy, Wyatt Young Warner
Characterization Of Local Void Content In Carbon Fiber Reinforced Plastic Parts Utilizing Observation Of In Situ Fluorescent Dye Within Epoxy, Wyatt Young Warner
Theses and Dissertations
Experimentation exploring the movement of voids within carbon fiber reinforced plastics was performed using fluorescent dye infused into the laminates observed through a transparent mold under ultraviolet light. In situ photography was used as an inspection method for void content during Resin Transfer Molding for these laminates. This in situ inspection method for determining the void content of composite laminates was compared to more common ex-situ quality inspection methods i.e. ultrasonic inspection and cross-section microscopy. Results for localized and total void count in each of these methods were directly compared to test samples and linear correlations between the three test …
Advanced Techniques For Carbon Nanotube Templated Microfabrication, Jason Matthew Lund
Advanced Techniques For Carbon Nanotube Templated Microfabrication, Jason Matthew Lund
Theses and Dissertations
Carbon nanotube templated microfabrication (CNT-M) is a term describing a grouping of processes where carbon nanotubes (CNTs) serve a structural role in the fabrication of a material or device. In its basic form, CNT-M is comprised of two steps: produce a template made from carbon nanotubes and infiltrate the porous template with an additional material. Vertically aligned carbon nanotube (VACNT) templates can be grown to heights ranging from microns to millimeters and lithographically patterned to a desired form. Deposition of an existing thin film material onto a CNT template will coat all template surfaces and can produce a near solid …
Durability Of Hybrid Large Area Additive Tooling For Vacuum Infusion Of Composites, Nathan Joseph Northrup
Durability Of Hybrid Large Area Additive Tooling For Vacuum Infusion Of Composites, Nathan Joseph Northrup
Theses and Dissertations
The purpose of this research was to scientifically validate potential cost-saving measures for production of large area additively manufactured tooling for vacuum infusion of composites. These cost saving measures included using a hybrid additive/subtractive manufacturing system to fabricate the mold, requiring lower capital cost and creating shorter lead times. Fiberglass reinforcement was used instead of carbon in the mold material. The validation was done by designing and fabricating a mold for a custom test artifact and analyzing the surface geometry over the course of multiple infusions until tool failure.After printing and machining, the mold required a sealer in order to …
Ultra-Low-Supply-Voltage Analog-To-Digital Converters, Alexander Craig Petrie
Ultra-Low-Supply-Voltage Analog-To-Digital Converters, Alexander Craig Petrie
Theses and Dissertations
This thesis presents techniques to implement analog-to-digital converters (ADCs) under an ultra-low-supply-voltage of 0.2 V to reduce the power consumption. The thesis proposes a dynamic bulk biasing circuit to adjust the PMOS bulk voltage to balance the NMOS and PMOS drain currents to guarantee functionality in the presence of process, voltage, and temperature variations. The dynamic bulk bias circuit is analyzed rigorously to show its functionality. This thesis also describes a new comparator suitable for a 0.2-V supply using ac-coupling, stacked input pairs, and voltage-boosted load capacitor. A 10-bit 5-kS/s successive-approximation-register (SAR) ADC in a 180-nm CMOS process with a …
Enabling Autonomous Operation Of Micro Aerial Vehicles Through Gps To Gps-Denied Transitions, James Scott Jackson
Enabling Autonomous Operation Of Micro Aerial Vehicles Through Gps To Gps-Denied Transitions, James Scott Jackson
Theses and Dissertations
Micro aerial vehicles and other autonomous systems have the potential to truly transform life as we know it, however much of the potential of autonomous systems remains unrealized because reliable navigation is still an unsolved problem with significant challenges. This dissertation presents solutions to many aspects of autonomous navigation. First, it presents ROSflight, a software and hardware architure that allows for rapid prototyping and experimentation of autonomy algorithms on MAVs with lightweight, efficient flight control. Next, this dissertation presents improvments to the state-of-the-art in optimal control of quadrotors by utilizing the error-state formulation frequently utilized in state estimation. It is …
Cooperative Navigation Of Fixed-Wing Micro Air Vehicles In Gps-Denied Environments, Gary James Ellingson
Cooperative Navigation Of Fixed-Wing Micro Air Vehicles In Gps-Denied Environments, Gary James Ellingson
Theses and Dissertations
Micro air vehicles have recently gained popularity due to their potential as autonomous systems. Their future impact, however, will depend in part on how well they can navigate in GPS-denied and GPS-degraded environments. In response to this need, this dissertation investigates a potential solution for GPS-denied operations called relative navigation. The method utilizes keyframe-to-keyframe odometry estimates and their covariances in a global back end that represents the global state as a pose graph. The back end is able to effectively represent nonlinear uncertainties and incorporate opportunistic global constraints. The GPS-denied research community has, for the most part, neglected to consider …
Groundwater Level Mapping Tool: Development Of A Web Application To Effectively Characterize Groundwater Resources, Steven William Evans
Groundwater Level Mapping Tool: Development Of A Web Application To Effectively Characterize Groundwater Resources, Steven William Evans
Theses and Dissertations
Groundwater is used worldwide as a major source for agricultural irrigation, industrial processes, mining, and drinking water. An accurate understanding of groundwater levels and trends is essential for decision makers to effectively manage groundwater resources throughout an aquifer, ensuring its sustainable development and usage. Unfortunately, groundwater is one of the most challenging and expensive water resources to characterize, quantify, and monitor on a regional basis. Data, though present, are often limited or sporadic, and are generally not used to their full potential to aid decision makers in their groundwater management.This thesis presents a solution to this under-utilization of available data …
An Experimental And Theoretical Investigation Of Internal Wave Kinetic Energy Density In Variable Stratifications, Allison Marie Lee
An Experimental And Theoretical Investigation Of Internal Wave Kinetic Energy Density In Variable Stratifications, Allison Marie Lee
Theses and Dissertations
Internal waves are generated in a fluid if the density increases continuously with depth. The variation in density with depth, or stratification, defines the natural frequency of the fluid N. Two common examples of stratified fluids are the ocean and atmosphere; internal waves are generated continuously in both mediums. Although there are many internal wave generation mechanisms, one common and frequently studied method is tidal flow over oceanic bathymetry. If the local natural frequency of the water near the topography is greater than the tidal frequencyω, internal waves will be generated by the tidal flow over the topography. If N=ω, …
Design And Measurement Of Strongarm Comparators, Nathan Robert Whitehead
Design And Measurement Of Strongarm Comparators, Nathan Robert Whitehead
Theses and Dissertations
The StrongARM comparator is utilized in many analog-to-digital converters (ADCs) because of its high power efficiency and rail-to-rail outputs. The performance of the comparator directly affects the speed, power, and accuracy of an ADC. However, the StrongARM comparator performance parameters such as delay, noise, and offset measured directly from silicon prototypes are rare in literature and often consist of small sample sets. In addition, existing techniques to measure the comparator require large chip areas, making it impractical to characterize a large number of comparators to obtain stochastic parameters such as offset and noise. This work presents novel circuit techniques to …