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2019

Virginia Commonwealth University

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Articles 31 - 50 of 50

Full-Text Articles in Engineering

Development Of An Eye Movement Based Predictive Model For Discrimination Of Parkinson's Disease From Other Parkinsonisms And Controls, Mary Anisa Kannan Jan 2019

Development Of An Eye Movement Based Predictive Model For Discrimination Of Parkinson's Disease From Other Parkinsonisms And Controls, Mary Anisa Kannan

Theses and Dissertations

Purpose: Due to the neurological aspects of Parkinson’s Disease (PD) and the sensitivity of eye movements to neurological issues, eye tracking has the potential to be an objective biomarker with higher accuracy in diagnosis than current clinical standards. Currently when PD is diagnosed clinically, there is an accuracy of 74% when diagnosed by a general practitioner and 82% when diagnosed by a movement disorder specialist. This study was designed to: 1. Assess eye movements as a potential biomarker for Parkinson’s Disease. 2. Determine if eye movements can distinguish between Parkinson’s Disease and commonly confounded movement disorders with parkinsonian symptoms. 3. …


Adhesion At Solid/Liquid Interfaces, Neda Ojaghlou Jan 2019

Adhesion At Solid/Liquid Interfaces, Neda Ojaghlou

Theses and Dissertations

The adhesion at solid/liquid interface plays a fundamental role in diverse fields and helps explain the structure and physical properties of interfaces, at the atomic scale, for example in catalysis, crystal growth, lubrication, electrochemistry, colloidal system, and in many biological reactions. Unraveling the atomic structure at the solid/liquid interface is, therefore, one of the major challenges facing the surface science today to understand the physical processes in the phenomena such as surface coating, self-cleaning, and oil recovery applications. In this thesis, a variety of theory/computational methods in statistical physics and statistical mechanics are used to improve understanding of water adhesion …


Fabrication And Simulation Of Nanomagnetic Devices For Information Processing, Justine L. Drobitch Jan 2019

Fabrication And Simulation Of Nanomagnetic Devices For Information Processing, Justine L. Drobitch

Theses and Dissertations

Nanomagnetic devices are highly energy efficient and non-volatile. Because of these two attributes, they are potential replacements to many currently used information processing technologies, and they have already been implemented in many different applications. This dissertation covers a study of nanomagnetic devices and their applications in various technologies for information processing – from simulating and analyzing the mechanisms behind the operation of the devices, to experimental investigations encompassing magnetic film growth for device components to nanomagnetic device fabrication and measurement of their performance.

Theoretical sections of this dissertation include simulation-based modeling of perpendicular magnetic anisotropy magnetic tunnel junctions (p-MTJ) and …


Electrochemical Separation Of Multivalent Species On A Liquid Bismuth Cathode In Licl-Kcl Eutectic For Used Nuclear Fuel Reprocessing, Michael Woods Jan 2019

Electrochemical Separation Of Multivalent Species On A Liquid Bismuth Cathode In Licl-Kcl Eutectic For Used Nuclear Fuel Reprocessing, Michael Woods

Theses and Dissertations

The presence of group I/II fission products (Cs-137, Sr-90, and Ba-137) within molten salt nuclear processes degrades operational efficiencies by contributing to increased radiation levels in the case of material handling processes or to loss of criticality in the case of a reactor. While methods such as zone freezing and ion exchange have been proven for the separation of these fission products in LiCl-KCl salts, they require extra equipment and processing steps. Addition of a liquid metal electrode to molten salt media, such as the electrorefiner of a pyroprocessing scheme or the salt cleaning stage of a molten salt fast …


Engineering Magnetic Properties Of Nanoparticles For Biomedical Applications And Magnetic Thin Film Composite Heterostructures For Device Applications., Shivakumar Hunagund Jan 2019

Engineering Magnetic Properties Of Nanoparticles For Biomedical Applications And Magnetic Thin Film Composite Heterostructures For Device Applications., Shivakumar Hunagund

Theses and Dissertations

The motivation of this study is to investigate the size dependent properties of Gadolinium silicide nanoparticles and their potential applications in Biomedicine. We use two approaches in our investigation - size dependence and possible exchange interaction in a core-shell structure. Past results showed Gd5Si4 NPs exhibit significantly reduced echo time compared to superparamagnetic iron oxide nanoparticles (SPION) when measured in a 7 T magnetic resonance imaging (MRI) system. This indicates potential use of Gd5Si4 ferromagnetic nanoparticles as T2 contrast agents for MRI.

Until recently most contrast agents (CA) that are used in Magnetic Resonance …


Modeling Cascading Failures In Power Systems In The Presence Of Uncertain Wind Generation, Mir Hadi Athari Jan 2019

Modeling Cascading Failures In Power Systems In The Presence Of Uncertain Wind Generation, Mir Hadi Athari

Theses and Dissertations

One of the biggest threats to the power systems as critical infrastructures is large-scale blackouts resulting from cascading failures (CF) in the grid. The ongoing shift in energy portfolio due to ever-increasing penetration of renewable energy sources (RES) may drive the electric grid closer to its operational limits and introduce a large amount of uncertainty coming from their stochastic nature. One worrisome change is the increase in CFs.

The CF simulation models in the literature do not allow consideration of RES penetration in studying the grid vulnerability. In this dissertation, we have developed tools and models to evaluate the impact …


A Computational Assessment Of Lisfranc Injuries And Their Surgical Repairs, Michael Perez Jan 2019

A Computational Assessment Of Lisfranc Injuries And Their Surgical Repairs, Michael Perez

Theses and Dissertations

While Lisfranc injuries in the mid foot are less common than other ankle and mid foot injuries, they pose challenges in both properly identifying them and treating them. When Lisfranc injuries are ligamentous and do not include obvious fractures, they are very challenging for clinicians to identify unless weight bearing radiographs are used. The result is that 20%-40% of Lisfranc injuries are missed in the initial evaluation. Even when injuries are correctly identified the outcomes of surgical procedures remain poor. Existing literature has compared the different surgical procedures but has not had a standard approach or procedures across studies. This …


Material Interactions And Self-Assembly In Inkjet Printing, Karam Nashwan Al-Milaji Jan 2019

Material Interactions And Self-Assembly In Inkjet Printing, Karam Nashwan Al-Milaji

Theses and Dissertations

Inkjet printing has attracted much attention in recent years as a versatile manufacturing tool, suitable for printing functional materials. This facile, low-cost printing technique with high throughput and accuracy is considered promising for a wide range of applications including but not limited to optical and electronic devices, sensors, solar cells, biochips, and displays. The performance of such functional devices is significantly influenced by the deposit morphology and printing resolution. Therefore, fabrication functional devices with precise footprints by inkjet printing requires deep understanding of ink properties, material interactions, and material self-assembly.

In conventional inkjet printing process, where sessile droplets are directly …


The Application Of Index Based, Region Segmentation, And Deep Learning Approaches To Sensor Fusion For Vegetation Detection, David L. Stone Jan 2019

The Application Of Index Based, Region Segmentation, And Deep Learning Approaches To Sensor Fusion For Vegetation Detection, David L. Stone

Theses and Dissertations

This thesis investigates the application of index based, region segmentation, and deep learning methods to the sensor fusion of omnidirectional (O-D) Infrared (IR) sensors, Kinnect sensors, and O-D vision sensors to increase the level of intelligent perception for unmanned robotic platforms. The goals of this work is first to provide a more robust calibration approach and improve the calibration of low resolution and noisy IR O-D cameras. Then our goal was to explore the best approach to sensor fusion for vegetation detection. We looked at index based, region segmentation, and deep learning methods and compared them with a goal of …


Metallic Systems At The Nano And Micro Scale: Bimetallic Nanoparticles As Catalysts And Mcraly Bond Coats In Thermal Barrier Coatings, Kenneth Kane Jan 2019

Metallic Systems At The Nano And Micro Scale: Bimetallic Nanoparticles As Catalysts And Mcraly Bond Coats In Thermal Barrier Coatings, Kenneth Kane

Theses and Dissertations

The dissertation is split into two parts. The first part will be focused on changes in material properties found at the nanoscale, as miscibility and electronic structure can change significantly with size. The formation of classically-immiscible bimetallic nanoparticles (BNPs) becomes favorable at the nanoscale and novel catalytic properties can emerge from the bimetallic alloying. The formation of alloyed and non-alloyed BNPs is achieved through pulse laser ablation (PLA) and a significant increase in catalytic activity is observed for both. Recently discovered, the increased activity in the non-alloyed BNPs, deemed multicomponent photocatalysis, is examined and the proposed mechanism discussed. The second …


Multi-Column Neural Networks And Sparse Coding Novel Techniques In Machine Learning, Ammar O. Hoori Jan 2019

Multi-Column Neural Networks And Sparse Coding Novel Techniques In Machine Learning, Ammar O. Hoori

Theses and Dissertations

Accurate and fast machine learning (ML) algorithms are highly vital in artificial intelligence (AI) applications. In complex dataset problems, traditional ML methods such as radial basis function neural network (RBFN), sparse coding (SC) using dictionary learning, and particle swarm optimization (PSO) provide trivial results, large structure, slow training, and/or slow testing. This dissertation introduces four novel ML techniques: the multi-column RBFN network (MCRN), the projected dictionary learning algorithm (PDL) and the multi-column adaptive and non-adaptive particle swarm optimization techniques (MC-APSO and MC-PSO). These novel techniques provide efficient alternatives for traditional ML techniques. Compared to traditional ML techniques, the novel ML …


The Role Of Kras In Mechanosensing In Non-Small Cell Lung Cancer, Krista M. Powell Jan 2019

The Role Of Kras In Mechanosensing In Non-Small Cell Lung Cancer, Krista M. Powell

Theses and Dissertations

Lung cancer is the number one cause of cancer related death worldwide, with more than 1.6 million fatalities each year. Non-small cell lung cancer (NSCLC) accounts for 80-85% of all lung cancers, with KRAS being one of the most prevalent oncogenic driver mutations. Therapeutic approaches for KRAS-mutated NSCLC have been extensively explored due to the US National Cancer Institute RAS Initiative, but methods of directly targeting KRAS or downstream effectors, such as MEK, still have poor results. Previous reports have shown that KRAS-mutated NSCLC activate distinct receptor tyrosine kinases (RTKs) depending on the epithelial or mesenchymal state. Epithelial-to-mesenchymal transition (EMT) …


Designing Biomimetic Implant Surfaces To Promote Osseointegration Under Osteoporotic Conditions By Revitalizing Mechanisms Coupling Bone Resorption To Formation, Ethan M. Lotz Jan 2019

Designing Biomimetic Implant Surfaces To Promote Osseointegration Under Osteoporotic Conditions By Revitalizing Mechanisms Coupling Bone Resorption To Formation, Ethan M. Lotz

Theses and Dissertations

In cases of compromised bone remodeling like osteoporosis, insufficient osseointegration occurs and results in implant failure. Implant retention relies on proper secondary fixation, which is developed during bone remodeling. This process is disrupted in metastatic bone diseases like osteoporosis. Osteoporosis is characterized low bone mass and bone strength resulting from either accelerated osteoclast-mediated bone resorption or impaired osteoblast-mediated bone formation. These two processes are not independent phenomena. In fact, osteoporosis can be viewed as a breakdown of the cellular communication connecting bone resorption to bone formation. Because bone remodeling occurs at temporally generated specific anatomical sites and at different times, …


Computational And Experimental Investigation On The Wetting Behavior Of Droplet-Fiber Systems, Hossain Aziz Jan 2019

Computational And Experimental Investigation On The Wetting Behavior Of Droplet-Fiber Systems, Hossain Aziz

Theses and Dissertations

Interaction of a liquid droplet and a fiber or layer of fibers is ubiquitous in nature and in a variety of industrial applications. It plays a crucial role in fog harvesting, coalescence filtration, membrane desalination, self-cleaning and fiber based microfluidics, among many others. This work presents a quantitative investigation on the interactions of a droplet with a fiber or layers of fibers. More precisely, the present work is focused on 1) predicting the effects of fiber’s size and material on its ability to withhold a droplet against external forces and on the liquid residue left on the fiber after the …


Cold X-Ray Effects On Satellite Solar Panels In Orbit, Myles Fogleman Jan 2019

Cold X-Ray Effects On Satellite Solar Panels In Orbit, Myles Fogleman

Theses and Dissertations

An exo-atmospheric nuclear detonation releases up to 80 percent of its’ energy as X-rays. Satellite’s solar cells and their protective coatings are vulnerable to low energy X-ray radiation. Cold X-rays (~1-1.5 keV) are absorbed close to the surface of materials causing the blow-off and rapid formation of Warm Dense Plasmas (WDPs), particularly in a gap between the unshielded active elements of solar cells. To understand how WDPs are created, it is necessary to investigate the power density distribution produced by cold X-rays for typical solar panel surface materials. The Monte Carlo stepping model implemented in the GEANT4 software toolkit is …


Assessment Of Access Methods For Mobile Maps For Individuals Who Are Blind Or Visually Impaired, David Parker Jan 2019

Assessment Of Access Methods For Mobile Maps For Individuals Who Are Blind Or Visually Impaired, David Parker

Theses and Dissertations

When people go to a mall, museums, or other such locations they tend to rely on maps to find their way around. However, for people who are blind or visually impaired (BVI) maps are not easily accessible and they depend on other means, such as a guide, to get around. Research has only just begun to investigate providing maps for people who are BVI on touch screen devices. Many different types of feedback have been used: audio (sound), tactile (touch), audio-tactile, and multitouch. Some research has been conducted on the benefit of using multiple fingers (multitouch) and has found conflicting …


Capillary Forces In Partially Saturated Thin Fibrous Media, Ali Moghadam Jan 2019

Capillary Forces In Partially Saturated Thin Fibrous Media, Ali Moghadam

Theses and Dissertations

Capillarity is often exploited in self-cleaning, drag reducing and fluid absorption/storage (sanitary products) purposes just to name a few. Formulating the underlying physics of capillarity helps future design and development of optimized structures. This work reports on developing computational models to quantify the capillary pressure and capillary forces on the fibrous surfaces. To this end, the current study utilizes a novel mass-spring-damper approach to incorporate the mechanical properties of the fibers in generating virtual fibrous structures that can best represent fibrous membranes. Such virtual fibrous structures are then subjected to a pressure estimation model, developed for the first time in …


Secure State Estimation In The Presence Of False Information Injection Attacks, Maitham Alsalman Jan 2019

Secure State Estimation In The Presence Of False Information Injection Attacks, Maitham Alsalman

Theses and Dissertations

In this dissertation, we first investigate the problem of source location estimation in wireless sensor networks (WSNs) based on quantized data in the presence of false information attacks. Using a Gaussian mixture to model the possible attacks, we develop a maximum likelihood estimator (MLE) to estimate the source location. The Cramer-Rao lower bound (CRLB) for this estimation problem is also derived.

Then, the assumption that the fusion center does not have the knowledge of the attack probability and the attack noise power investigated. We assume that the attack probability and power are random variables which follow certain uniform distributions. We …


Engineering The Alveolar Gas Exchange Barrier With Extracellular Matrix Coatings For Bioengineered Lungs, Bethany M. Young Jan 2019

Engineering The Alveolar Gas Exchange Barrier With Extracellular Matrix Coatings For Bioengineered Lungs, Bethany M. Young

Theses and Dissertations

Lower respiratory diseases are currently the third leading cause of death worldwide. For many end-stage patients with these diseases, there is no cure and a shortage of donor organs available for transplant. A promising solution is to design regenerative scaffolds or complete bioengineered lungs, using decellularized lung tissues as a template for regeneration. Recent advances in the field have made significant strides towards developing a transplantable lung. However, the current technology has not produced a functional lung for in vivo transplant due to immature gas exchange barriers. The mechanisms driving alveolar barrier maturation and role that extracellular matrix (ECM) plays …


Sensor Placement For Damage Localization In Sensor Networks, Fereshteh Firouzi Jan 2019

Sensor Placement For Damage Localization In Sensor Networks, Fereshteh Firouzi

Theses and Dissertations

The objective of this thesis is to formulate and solve the sensor placement problem for damage localization in a sensor network. A Bayesian estimation problem is formulated with the time-of-flight (ToF) measurements. In this model, ToF of lamb waves, which are generated and received by piezoelectric sensors, is the total time for each wave to be transmitted, reflected by the target, and received by the sensor. The ToF of the scattered lamb wave has characteristic information about the target location. By using the measurement model and prior information, the target location is estimated in a centralized sensor network with a …