A Deep Learning Approach To Detect Diabetic Retinopathy In Fundus Images., Winston R. Furtado

Electronic Theses and Dissertations

Background: Diabetic retinopathy is a disease caused due by complications of diabetes mellitus which can lead to blindness. About 33% of the US population with diabetes also show symptoms for diabetes retinopathy. If not treated, diabetic retinopathy worsens over time by progressing through two main pathological stages of non-proliferative and proliferative and four clinical stages. While the diagnostic accuracy of detecting diabetic retinopathy through machine learning have shown to be successful for OCT images, the accuracy of ultra-widefield fundus images have yet to be fully reported. This paper describes a method to non-invasively detect and diagnose diabetic retinopathy from ultra-widefield …

Suture-Less Trocar Site Closure Clip, Hares A. Patel

Electronic Theses and Dissertations

Introduction: Following laparoscopic surgery, there is a need, in many cases, to close trocar sites to prevent hernias. Currently, devices that exist on the market are suture based, but the lack of standardization in the suturing techniques together with the time-consuming nature of the procedure leads to the need for improvement in trocar site closure products. Trocar closure sites do not need to be fully closed on the fascial layer; rather, sufficiently blocking the hole at the abdominal wall can significantly reduce post-operative herniation. A retrospective study on trocar site herniation (TSH) after laparoscopic surgery indicates a TSH incidence …

Experimental Investigation Of The Manufacture Of Tunable Graphene Oxide Filter Membranes Using Intense Pulse Light, Joshua H Kotter

Electronic Theses and Dissertations

Reduced graphene oxide is a thin, strong, and inexpensive material with a channel and pore structure that make it a promising candidate for a filtration material. Reduced graphene oxide has been produced and tested in the laboratory, but a lack of scalable manufacturing techniques have limited its commercial use.

This thesis has shown that graphene oxide can be rapidly manufactured with an industrially scalable flash reduction process. The flash reduction process uses 0.58 millisecond pulses from a xenon lamp to reduce the graphene oxide film in less than a minute. Results for partially reduced graphene oxide membranes tuned by the …

Characterization And Optimization Of A Propeller Test Stand, Colin Bruce Leighton Benjamin

Mechanical & Aerospace Engineering Theses & Dissertations

In recent history, there has been a rapid rise in the use of drones, and they are expanding in popularity each year. The widespread use and future capabilities of these unmanned aerial vehicles (UAVs) will call for increased study and classification of propellers to maximize their performance. As a result, it is necessary to have continuity in the development, maximization, and optimization of propeller test stand’s capability to collect accurate and precise measurements. It is of significant advantage to have the capability of accurately characterizing a propeller based on its thrust and torque. In this study, a propeller test stand …

Knowledge Sharing And Creative Confidence In Promoting Employees’ Creative Behavior, Elnaz Dario

Engineering Management & Systems Engineering Theses & Dissertations

The purpose of this research is to investigate the influence of knowledge sharing and creative confidence on the relationship between organizations’ creative environment and employees’ creative behavior. This study individually assesses the relationship between factors from heterogeneous survey participant data and compares the result for two groups; engineers and non-engineers. A theoretical framework is adopted to explain how a creative climate stimulates an individual’s creative behavior and how this relationship is moderated and mediated by knowledge sharing and creative confidence. This is a relatively unexplored concept in the current literature. The results demonstrated that knowledge sharing and creative confidence significantly …

Effects Of Control Device And Task Complexity On Performance And Task Shedding During A Robotic Arm Task, Shelby K. Long

Psychology Theses & Dissertations

The use of robotic arms across domains is increasing, but the relationship between control features and performance is not fully understood. The goal of this research was to investigate the difference in task performance when using two different control devices at high and low task complexities when participants can shed tasks to automation. In this experiment, 40 undergraduates (24 females) used two control devices, a Leap Motion controller and an Xbox controller, to teleoperate a robotic arm in a high or low complexity peg placement task. Simultaneously, participants were tasked with scanning images for tanks. During the experiment, participants had …

Solid State Polyaniline Supercapacitors Based On Electrodes Fabricated With Electropolymerization, Jonathan R. Blincoe

Electrical & Computer Engineering Theses & Dissertations

Supercapacitors are energy storage devices with the potential to overshadow lithium-ion batteries in the energy storage sector. Generally supercapacitors store less energy than a lithium-ion battery, but make up for it with much higher power densities that allow supercapacitors to charge and discharge quickly. This can be through the formation of an electric double layer or faradaic phenomenon between the electrode and electrolyte. The energy storage mechanism relies heavily on the electrode material and the ions contained within the electrolyte. In this research, polyaniline was used as an active material to prepare supercapacitors. Polyaniline is a conductive polymer that is …

Effect Of Grain Size And Interface Engineering On The Photovoltaic Performance And Stability Of Perovskite Solar Cells, Abdullah Al Mamun

Electrical & Computer Engineering Theses & Dissertations

Organic-inorganic halide perovskite solar cells (PSCs) have grown rapidly in recent years due to their outstanding optoelectronic properties, high efficiency, and low-cost. However, this emerging solar cell technology is experiencing some challenges such as defects, hysteresis, and long-term stability, which need to be addressed in order to make it commercially available. This dissertation aims to assist in overcoming some of the barriers and is therefore important to the field of perovskite solar cells.

Initially, this dissertation focuses on investigating the role of grain interiors (GIs) and grain boundaries (GBs) of perovskite film using chemically, spatially, and temporally resolved measurements at …

A Dual Nanostructured Approach To Sers Amenable To Large-Scale Production, Kory Brian Castro

Chemistry & Biochemistry Theses & Dissertations

A SERS device was made using a dual-nanostructured surface comprised of silver nanoparticle and silver nanowires. The ability of each nanostructure to produce a uniform surface was characterized and the surface-enhanced Raman scattering (SERS) response of the resulting surfaces were examined using the reporter molecule 4-aminothiolphenol (ATP) and a 638 nm excitation laser.

A synthetic method was developed to produce silver nanowires with lengths of ~20 μm and diameters of ~100 nm with a narrow size distribution. The method utilized a simple, one-pot synthesis that is amenable to large-scale production. A selective precipitation method was used to the isolate the …

Mimo Radar Waveform Design And Sparse Reconstruction For Extended Target Detection In Clutter, Christopher Alan Rogers

Electrical & Computer Engineering Theses & Dissertations

This dissertation explores the detection and false alarm rate performance of a novel transmit-waveform and receiver filter design algorithm as part of a larger Compressed Sensing (CS) based Multiple Input Multiple Output (MIMO) bistatic radar system amidst clutter. Transmit-waveforms and receiver filters were jointly designed using an algorithm that minimizes the mutual coherence of the combined transmit-waveform, target frequency response, and receiver filter matrix product as a design criterion. This work considered the Probability of Detection (P _D) and Probability of False Alarm (P _FA) curves relative to a detection threshold, τ _th, Receiver Operating Characteristic (ROC), …

Evaluating Stakeholder Bias In Stakeholder Analysis In Social Media, Ahmad A. Bajarwan

Engineering Management & Systems Engineering Theses & Dissertations

Stakeholder analysis is the first step in the planning of most infrastructure projects. Selecting and then applying the best method for a project’s stakeholder analysis is extremely important for correctly assessing stakeholder opinions. Social media platforms allow stakeholders to participate directly in analysis. However, as with most other analysis methods, social media introduces inherent biases.

Social media is a powerful tool for communication and networking, and it also provides a valuable source of information for analyzing user opinions about infrastructure projects. By using data collected from Twitter, analysts can create networks to represent connections among users, quantify their similarities, and …

A Data-Driven Approach For Modeling Agents, Hamdi Kavak

Computational Modeling & Simulation Engineering Theses & Dissertations

Agents are commonly created on a set of simple rules driven by theories, hypotheses, and assumptions. Such modeling premise has limited use of real-world data and is challenged when modeling real-world systems due to the lack of empirical grounding. Simultaneously, the last decade has witnessed the production and availability of large-scale data from various sensors that carry behavioral signals. These data sources have the potential to change the way we create agent-based models; from simple rules to driven by data. Despite this opportunity, the literature has neglected to offer a modeling approach to generate granular agent behaviors from data, creating …

Off Axis Compressive Response Of Ice-Templated Ceramics, Rahul Kumar Jujjavarapu

Mechanical & Aerospace Engineering Theses & Dissertations

The off-axis compressive behavior of ice-templated ceramic was analyzed using experimental results and micro-mechanical model simulation. Ice-templated ceramics is a versatile processing technique used to manufacture anisotropic ceramic foam by exploiting the anisotropic growth characteristics and lamellar morphology. The ice-templating process results in processing-structure-property relationships determined by the microstructure. The processed alumina samples which were later manufactured by water jet machine from the freeze casting were tested under quasi-static off-axis loading conditions and were used to determine the mechanical properties of the material. Digital image correlation (DIC) was used to measure the strain response of ice-templated ceramic under off-axis loading. …

Design And Manufacture Of An Inertial Cascade Impactor For Industrial Hygiene Purposes, Hector Joel Gortaire

Mechanical & Aerospace Engineering Theses & Dissertations

Inertial cascade impactors are devices commonly used for industrial hygiene and pharmaceutical studies. Their main purpose is to separate particulate matter suspended in aerosols according to their sizes, which can vary from over 10 µm to 0.5 µm. Their versatility and ease of operation make them suitable for on-site sampling; however, designing them requires a careful consideration of the different geometric parameters that characterize them.

In this thesis, a 5-stage inertial cascade impactor was designed, modelled, constructed, and tested. The main design parameter was the volumetric flow rate, 40 l/min, which was provided by a vacuum pump. By continuous iterations, …

Radio Frequency Toolbox For Drone Detection And Classification, Abdulkabir Bello

Electrical & Computer Engineering Theses & Dissertations

The continuous development of inexpensive embedded sensors has led to the rapid proliferation of new civilian use of unmanned aerial vehicle (UAVs) or drones. It is now easier for civilians to own drones as the cost falls. As we all know drones have a variety of important applications and can also be used for negative effects too. These drones can pose a threat to the security of the population either civilian, organization or industry. There is a need for Radio Frequency Signal Classification (RF-Class) toolbox which can monitor, detect, and classify RF signals from drone communication system. The ability to …

Latent Choice Models To Account For Misclassification Errors In Discrete Transportation Data, Lacramioara Elena Balan

Civil & Environmental Engineering Theses & Dissertations

One of the most fundamental tasks when it comes to analyzing data using statistical methods is to understand the relationship between the explanatory variables and the outcome. Misclassification of explanatory variables is a common risk when using statistical modeling techniques. In this dissertation, we define ‘misclassification,’ as a response that is reported or recorded in the wrong category; for example, a variable is registered as a one when it should have the value zero. Misclassification can easily happen in any data; for example, in an interview setting where the respondent misunderstands the question or the interviewer checks the wrong box. …

Numerical Simulation Of Viscoelastic Flow In Micro/Nanochannels, Lanju Mei

Mechanical & Aerospace Engineering Theses & Dissertations

Micro/Nanofluidic devices often involve use of biological fluids or polymeric solutions that cannot be simply treated as Newtonian fluids. The numerical simulation for the complex fluids at micro/nanoscale presents a significant computational challenge, and the inclusion of electrokinetic body force further increases the complexity. Specifically, the well-known High Weissenberg Number Problem (HWNP) has become a challenge for the numerical simulation of viscoelastic fluid. This dissertation is aimed to develop a numerical tool to simulate the behavior of viscoelastic fluid in the micro/nanochannel. The most popular log-conformation reformulation to solve the HWNP is presented and implemented in a finite volume scheme. …

A Framework For Test & Evaluation Of Autonomous Systems Along The Virtuality-Reality Spectrum, Nathan D. Gonda

Computational Modeling & Simulation Engineering Theses & Dissertations

Test & Evaluation of autonomous vehicles presents a challenge as the vehicles may have emergent behavior and it is frequently difficult to ascertain the reason for software decisions. Current Test & Evaluation approaches for autonomous systems place the vehicles in various operating scenarios to observe their behavior. However, this introduces dependencies between design and development lifecycle of the autonomous software and physical vehicle hardware. Simulation-based testing can alleviate the necessity to have physical hardware; however, it can be costly when transitioning the autonomous software to and from a simulation testing environment. The objective of this thesis is to develop a …

An Investigation Of General Criteria For Assessing Space Flight Systems Of Diverse Mission Concept Designs, Cindy L. Daniels

Engineering Management & Systems Engineering Theses & Dissertations

The purpose of this research is to investigate the general criteria for assessing the technical implementation risk factors of proposed space science missions at the mission concept stage. According to the National Aeronautics and Space Administration (NASA) Space Flight Program and Project Management Handbook (NASA, 2012), the mission concept review objectives are “To evaluate the feasibility of the proposed mission concept(s) and its fulfillment of the program's needs and objectives. To determine whether the maturity of the concept and associated planning are sufficient to begin Phase A” (p.33). Experts previously defined two technical risk factors, to assess aspects of the …

Measuring And Modeling Bare Desert Wind Erosion From Steppe Grassland Of Northern China As Affected By Soil Moisture And Climate, Nicholas Morgan Potter

Civil & Environmental Engineering Theses & Dissertations

Soil erosion by wind has been found to be negatively related to soil water content, as evidenced by that for a given area, such a soil erosion can be much less in a wet than a dry year. However, few studies have examined the functional relationship between wind erosion and soil moisture, primarily due to lack of field measured data. The objectives of this study were to: 1) measure wind erosion in field using a portable wind tunnel devised and made by the author; 2) use the measured data to calibrate/validate a wind erosion model previously developed by the author; …

Sidestream Ras Fermentation For Stable Bio-P Combined With Short Cut Nitrogen Removal In An A/B Process, Lindsey Elise Ferguson

Civil & Environmental Engineering Theses & Dissertations

It is well known that soluble organic carbon (sCOD), especially in the form of volatile fatty acids (VFA), is critical to achieving reliable enhanced biological phosphorus removal (EBPR) in biological nutrient removal (BNR) processes. Consistent and reliable EBPR in systems treating wastewaters deficient in sCOD may be accomplished by the addition of VFA and sCOD – rich fermentate produced by the fermentation of primary sludge, return / waste activated sludge (RAS / WAS), or other suitable carbon sources. The solids retention time (SRT) of fermenters being used to supplement carbon in sidestream EBPR processes must be controlled such that complex …

Cyber Security- A New Secured Password Generation Algorithm With Graphical Authentication And Alphanumeric Passwords Along With Encryption, Akash Rao

Electrical & Computer Engineering Theses & Dissertations

Graphical passwords are always considered as an alternative of alphanumeric passwords for their better memorability and usability [1]. Alphanumeric passwords provide an adequate amount of satisfaction, but they do not offer better memorability compared to graphical passwords [1].

On the other hand, graphical passwords are considered less secured and provide better memorability [1]. Therefore many researchers have researched on graphical passwords to overcome the vulnerability. One of the most significant weaknesses of the graphical passwords is "Shoulder Surfing Attack," which means, sneaking into a victim's computer to learn the whole password or part of password or some confidential information. Such …

Estimating Cognitive Workload In An Interactive Virtual Reality Environment Using Electrophysiological And Kinematic Activity, Christoph Tremmel

Biomedical Engineering Theses & Dissertations

As virtual reality (VR) technology continues to gain prominence in commercial, educational, recreational and research applications, there is increasing interest in incorporating physiological sensors in VR devices for passive user-state monitoring to eventually increase the sense of immersion. By recording physiological signals such as the electroencephalogram (EEG), electromyography (EMG) or kinematic parameters during the use of a VR device, the user’s interactions in the virtual environment could be adapted in real time based on the user’s cognitive state. This dissertation evaluates the feasibility of passively monitoring cognitive workload via electrophysiological and kinematic activity while performing a classical n-back task in …

Variable Speed Limit Control At Sag Curves Through Connected Vehicles: Implications Of Alternative Communications And Sensing Technologies, Reza Vatani Nezafat

Civil & Environmental Engineering Theses & Dissertations

Connected vehicles (CVs) will enable new applications to improve traffic flow. This study’s focus is to investigate how potential implementation of variable speed limit (VSL) through different types of communication and sensing technologies on CVs may improve traffic flow at a sag curve. At sag curves, the gradient changes from negative to positive values which causes a reduction in the roadway capacity and congestion. A VSL algorithm is developed and implemented in a simulation environment for controlling the inflow of vehicles to a sag curve on a freeway to minimize delays and increase throughput. Both vehicle-to-vehicle (V2V) and infrastructure-to-vehicle (I2V) …

On Analytic Nonlinear Input-Output Systems: Expanded Global Convergence And System Interconnections, Irina M. Winter Arboleda

Electrical & Computer Engineering Theses & Dissertations

Functional series representations of nonlinear systems first appeared in engineering in the early 1950’s. One common representation of a nonlinear input-output system are Chen-Fliess series or Fliess operators. Such operators are described by functional series indexed by words over a noncommutative alphabet. They can be viewed as a noncommutative generalization of a Taylor series. A Fliess operator is said to be globally convergent when its radius of convergence is infinite, in other words, when there is no a priori upper bound on both the L1-norm of an admissible input and the length of time over which the corresponding output is …

Development And Initial Evaluation Of A Reinforced Cue Detection Model To Assess Situation Awareness In Commercial Aircraft Cockpits, Aysen K. Taylor

Engineering Management & Systems Engineering Theses & Dissertations

Commercial transport aircraft of today vary greatly from early aircraft with regards to how the aircraft are controlled and the feedback provided from the machine to the human operator. Over time, as avionics systems became more automated, pilots had less direct control over their aircraft. Much research exists in the literature about automation issues, and several major accidents over the last twenty years spurred interest about how to maintain the benefits of automation while improving the overall human-machine interaction as the pilot is considered the last line of defense.

An important reason for maintaining or even improving overall pilot situation …

A Utility Framework For Selecting Immersive Interactive Capability And Technology For Virtual Laboratories, Shuo Ren

Computational Modeling & Simulation Engineering Theses & Dissertations

There has been an increase in the use of virtual reality (VR) technology in the education community since VR is emerging as a potent educational tool that offers students with a rich source of educational material and makes learning exciting and interactive. With a rise of popularity and market expansion in VR technology in the past few years, a variety of consumer VR electronics have boosted educators and researchers’ interest in using these devices for practicing engineering and science laboratory experiments. However, little is known about how such devices may be well-suited for active learning in a laboratory environment. This …

Estimation Of Arterial Wall Parameters Via Model-Based Analysis Of Noninvasively Measured Arterial Pulse Signals, Dan Wang

Mechanical & Aerospace Engineering Theses & Dissertations

This dissertation presents a model-based method for estimating arterial wall parameters from noninvasively measured arterial pulse signals via a microfluidic-based tactile sensor. The sensor entails a polydimethylsiloxane (PDMS) microstructure embedded with 5×1 transducer array built on Pyrex/Polyethylene terephthalate (PET) substrate. The arterial pulse causes a time-varying deflection on the top of the PDMS microstructure, which registers as a resistance change by the transducer at the site of the artery.

Owing to the time-harmonic nature of its radial motion, the arterial wall is modeled as a second-order dynamic system. By combining this dynamic model with a hemodynamic model of blood flow, …

Quantifying Impact Of Cyber Actions On Missions Or Business Processes: A Multilayer Propagative Approach, Unal Tatar

Engineering Management & Systems Engineering Theses & Dissertations

Ensuring the security of cyberspace is one of the most significant challenges of the modern world because of its complexity. As the cyber environment is getting more integrated with the real world, the direct impact of cybersecurity problems on actual business frequently occur. Therefore, operational and strategic decision makers in particular need to understand the cyber environment and its potential impact on business. Cyber risk has become a top agenda item for businesses all over the world and is listed as one of the most serious global risks with significant financial implications for businesses.

Risk analysis is one of the …

Comparison Of Support Methods For Static Aerodynamic Testing And Validation Of A Magnetic Suspension And Balance System, Cameron K. Neill

Mechanical & Aerospace Engineering Theses & Dissertations

Magnetic suspension wind tunnels offer an alternative to traditional physical support methods. They allow for the collection of support interference free data and broader dynamic test capabilities than existing methods. Determination of dynamic aerodynamic characteristics is a crucial portion of the design of new re-entry capsules. A NASA initiative restored the 6-inch Magnetic Suspension and Balance System to support the design of a new MSBS for a supersonic wind tunnel. Before a new MSBS can be constructed, the characteristics of the current MSBS must be examined.

This thesis discusses the calibration and validation of the 6-inch MSBS. After calibration, three …