Engineering Commons^™

Bayesian Model Averaging Based Storage Lifetime Assessment Method For Rubber Sealing Rings, Di Liu, Shaoping Wang, Chao Zhang, Mileta M. Tomovic

Engineering Technology Faculty Publications

Rubber sealing ring is one of the most widely used seals. It is always stored for a period of time before put into use, especially in aeronautic and aerospace applications. It is necessary to evaluate the storage lifetime of rubber sealing rings. However, due to the long storage lifetime of rubber sealing rings, two issues need to be handled, including model uncertainty and lack of storage lifetime data. A Bayesian model averaging based storage lifetime assessment method for rubber sealing rings is proposed in this article. The Gamma distribution model and Weibull distribution model are selected as the candidate models …

Reliability Estimation Of Reciprocating Seals Based On Multivariate Dependence Analysis And It's Experimental Validation, Chao Zhang, Rentong Chen, Shaoping Wang, Yujie Qian, Mileta M. Tomovic

Engineering Technology Faculty Publications

Accurate reliability estimation for reciprocating seals is of great significance due to their wide use in numerous engineering applications. This work proposes a reliability estimation method for reciprocating seals based on multivariate dependence analysis of different performance indicators. Degradation behavior corresponding to each performance indicator is first described by the Wiener process. Dependence among different performance indicators is then captured using D-vine copula, and a weight-based copula selection method is utilized to determine the optimal bivariate copula for each dependence relationship. A two-stage Bayesian method is used to estimate the parameters in the proposed model. Finally, a reciprocating seal degradation …

Improving Stem Recruitment Through A Theme-Based Summer Residential Camp Focused On Sea Level Rise, Vukica M. Jovanović, Balša Terzić, Mujde Erten-Unal, Victoria Hill, George Mcleod, Michelle Covi, David Burdige, Jenifer Alonzo, Justin Mason, Tysha Batts, Cynthia Tomovic

Engineering Technology Faculty Publications

In this paper, the authors present an enrichment program that focuses on Science, Technology, Engineering, and Math (STEM) concepts. The program is named Building Leaders to Advance Science and Technology (BLAST) and is held each summer at three universities across the Commonwealth of Virginia: Old Dominion University, the University of Virginia, and the Virginia Polytechnic Institute. BLAST is sponsored in partnership among these three universities and the Virginia Space Grant Consortium (VSGC), and is funded by the General Assembly of Commonwealth of Virginia. Its main purpose is to expose high school students to topics related to different STEM fields through …

Experimental Verification Of Transparent Spin Mode In Rhic, V. S. Morozov, P. Adams, Y. S. Derbenev, Y. Filatov, H. Huang, A. M. Kondratenko, M. A. Kondratenko, F. Lin, F. Méot, V. Ptitsyn, W. B. Schmidke, Y. Zhang

Engineering Technology Faculty Publications

High electron and ion polarizations are some of the key design requirements of a future Electron Ion Collider (EIC). The transparent spin mode, a concept inspired by the figure 8 ring design of JLEIC, is a novel technique for preservation and control of electron and ion spin polarizations in a collider or storage ring. It makes the ring lattice "invisible" to the spin and allows for polarization control by small quasi-static magnetic fields with practically no effect on the beam’s orbital characteristics. It offers unique opportunities for polarization maintenance and control in Jefferson Lab’s JLEIC and in BNL’s eRHIC. The …

Training The Active Duty Naval Workforce Using The Digital Thread To Design/Redesign Basic Models With Validation Through The Additive Manufacturing, Vukica M. Jovanovic, Anthony W. Dean, Karina Arcaute, Michel Audette, Dipankar Ghosh

Engineering Technology Faculty Publications

This digest will showcase one approach to teaching engineering graphics and design for the active duty naval workforce. Sailors are exposed to solid modeling fundamentals during the two-day long workshop. Solid modeling is taught in connection to concepts of digital thread and design for additive manufacturing. Engineering graphics fundamentals are introduced with the emphasis on a deeper understanding of machinist approach, often used for an easier understanding of Boolean algebra, which is embedded within the Computer Aided Design tools and discusses how the design for additive manufacturing would differ from that approach. Moreover, special attention is given to understanding the …

Elucidation Of The Catalytic Partial Oxidation Of Methane Utilizing The One-Of-A-Kind Catalytic Shock Tube Technique, Robyn E. Smith

Dissertations and Theses

The mechanism for the catalytic partial oxidation of methane has been debated in scientific literature for over 20 years. This is a seemingly simple reaction producing CO, CO₂, H₂ and H₂O through either partial oxidation followed by complete oxidation or complete oxidation followed by reforming steps. What is happening when the reaction is allowed to occur in an environment absent of transport limitations, absent of temperature gradients and temperature changes, absent of boundary layers must be understood and, until now, has yet to be achieved in one experimental technique.

A novel method using a one …

Void Fraction Measurements In Large (0.3 M) Diameter Bubble Column Using Wire Mesh Sensor And Pressure Transducers- Effect Of Sparger, Afolabi Gabriel Ojo

Dissertations and Theses

The importance of the accurate temporal and spatial measurements of the two-phase flow parameters in bubble columns is very well known. The aim of this research work is to report the spatial measurements of the void fraction distribution in a 30 cm diameter cylindrical bubble column using Wire Mesh Sensor (WMS) tomography and Pressure Transducers. Pair of WMS sensors, with a 64×64 wire configuration of each sensor, were installed which are separated by a distance along the axis of the bubble column. Wire Mesh Sensors and PTs Data were collected for time-averaged and transient with a sampling frequency of 1000 …

Neuron-Glial (Ng) Interactions: A Microfluidic Examination Of Ng Emergent Responses For Repair, Tanya Singh

Dissertations and Theses

Neuron-glia communication is crucial to the development, plasticity, and repair of the nervous system (NS). While neurons are well known to conduct electrical impulses that transfer biological information and stimuli throughout the NS, our understanding of the roles of glia continues to evolve from when the cells were largely believed to act solely for neuronal support. Recent decades of research has shown that glia can alter metabolism, conduct impulses and change phenotype for NS repair. NG interactions have, thereby, become heavily researched in varied areas of biomedical engineering, including embryogenesis, neural regeneration, growth, and intracellular synaptic activity. However, while NG …

Controlled Migration Of Retinal Progenitor Cells Within Electro-Chemotactic Fields, Shawn Mishra

Dissertations and Theses

Vision loss in retinal degenerative diseases is overwhelmingly attributed to damage and death of retinal photoreceptor cells. Studies in mouse retina have suggested that transplantation of isolated post-natal or stem cell-derived retinal progenitor cells (RPCs) to replace apoptotic or damaged photoreceptors may be a novel approach to restore vision. Thus far, outcomes project that the amount of restored visual response depends upon the migration of transplanted cells from insertion in the sub-retinal space to the outer nuclear layer (ONL). However, transplantation efficiency is exceedingly low – ~5% cells transplanted enter the retina – directly limiting the efficacy of the treatments. …

Translational Modeling Of Non-Invasive Electrical Stimulation, Dennis Quangvinh Truong

Dissertations and Theses

Seminal work in the early 2000’s demonstrated the effect of low amplitude non-invasive electrical stimulation in people using neurophysiological measures (motor evoked potentials, MEPs). Clinical applications of transcranial Direct Current Stimulation (tDCS) have since proliferated, though the mechanisms are not fully understood. Efforts to refine the technique to improve results are on-going as are mechanistic studies both in vivo and in vitro. Volume conduction models are being applied to these areas of research, especially in the design and analysis of clinical montages. However, additional research on the parameterization of models remains.

In this dissertation, Finite Element Method (FEM) models of …

Ict-Enabled Control And Energy Management Of Community Microgrids For Resilient Smart Grid Operation, Mahmoud Saleh

Dissertations and Theses

Our research has focused on developing novel controllers and algorithms to enhance the resilience of the power grid and increase its readiness level against major disturbances.

The U.S. power grid currently encounters two main challenges: (1) the massive and extended blackouts caused by natural disasters, such as hurricane Sandy. These blackouts have raised a national call to explore innovative approaches for enhanced grid resiliency. Scrutinizing how previous blackouts initiated and propagated throughout the power grid, the major reasons are lack of situational awareness, lack of real-time monitoring and control, underdeveloped controllers at both the transmission and distribution levels, and lack …

The Influence Of Size And Progression Of Intra-Cerebral Hematoma On The Lateral Ventricles, Muhammad J. Ashraf

Dissertations and Theses

Cerebrovascular diseases like intra cerebral hemorrhage are quite deadly and may disturb functioning of the brain, expanding and resulting in formation of an intra cerebral hematoma(ICH). It is imperative to comprehend how hematoma and its expansion inside the brain endangers human life. One of the influences of an ICH inside brain tissue is on the Lateral Ventricles(LV). When the hemorrhage occurs close enough to the lateral ventricles, filled with cerebrospinal fluid(CSF), it disrupts the balance of fluid in LV. A minor pressure change in LV can negatively influence the production of CSF as well as an increase in intracranial pressure. …

Global Food Security Under Climate-Water-Energy Nexus, Ehsan Najafi

Dissertations and Theses

During the last few decades, the global agricultural production has risen and technology enhancement is still contributing to yield growth. However, population growth, water and energy crisis, and extreme weather, climate change, etc. threaten the global food security. The focus of this study is to advance the understanding of the associations between crops productivity and large scale and local scale climatic variables, climate change, technology enhancement and assessing food-water-energy nexus to enhance global food security in a sustainable manner considering current available resources. As decision-makers try to improve food security, it is important to identify the impact of technology enhancement …

Air Ingress And Heat-Driven Flow Relaminarization In A Very High Temperature Reactor (Vhtr), Apoorva Rudra

Dissertations and Theses

Very High Temperature Reactors (VHTRs) are one of six Generation IV reactors that have been proposed for DOE’s Next Generation Nuclear Plant. In addition to using gaseous coolants, VHTRs also display benefits of passive safety systems including intra-core natural circulation for heat removal in accident scenarios. However, a number of substantial engineering challenges are expected in VHTRs, and due to the high temperatures of the coolant involved, material behavior in various components needs to be better understood. Our work focuses mainly on two key phenomena that could lead to localized hot spots in the VHTR reactor core if not addressed …

Literature Survey Of Wet-Waste And Hydrothermal Carbonization System: A Comparative Evaluation, Ramat Olaide Yusuf

Dissertations and Theses

This thesis describes the process of Hydrothermal carbonization and a comparative assessment on recent work done on the process using different feedstocks such as Raw Apple (RA), Apple chip pomace (ACP), apple juice pomace (AJP), grape pomace (GP), macadamia nut-shell (MNS), Sewage Sludge (SS), Poultry Litter (PL) and Grape Marc (GM). The data obtained from the literature survey was compared with the data obtained by the CCL team on the SWPS gasifier (HTC of poultry litter) to obtain how carbon conversion efficiency, syngas composition, thermal efficiency, char production rate, gas production rate and energy utilization vary with carbonization process conditions, …

Investigation Of The Synthesis And Optoelectronic Properties Of Ultrasmall Cdse Quantum Dots, Megan Webster

Dissertations and Theses

Traditional, or 1^st generation, solar cells have a theoretical upper limit of 33% power conversion efficiency based on the thermodynamic limitation of the single p-n junction cell design. This limitation is known as the Shockley-Queisser limit and methods to design solar cells to circumvent it have been creative, with a significant part of the field focused on quantum dot (QD) based systems. With theoretical efficiencies ranging between 44 and 67% for one sun concentration, QD solar cell designs are clearly superior to the limits of 1^st generation solar cells. However, maximum achieved efficiencies for QD-based designs are far …

Sniffing, Decoding And Decryption Of Gsm Signals Using Low Cost Hardware And Open-Source Software, Muhammad Talha Choudhry

Dissertations and Theses

We have participated in the creation of almost two terabytes of tables aimed at cracking A5/1, the most common ciphering algorithm used in GSM. Given 114-bit of known plaintext, we are able to recover the session key with a hit rate of 19%. The tables are expected to be unique as they provide the best coverage yet known to the authors and research workers and they are the first step in a real-world passive attack against GSM. An initial investigation and analysis into the air interface of GSM were performed, from both a theoretical and practical point of view. These …

Electrochemical Properties Of Crystalline Polymorphs Of Mno2 In Aluminum And Zinc Metal Batteries, Subhadip Pal

Dissertations and Theses

The widespread use of non-renewable fossil fuels has led to societal problems like global warming and climate change. Electrochemical energy storage can enable the integration of renewable energy sources that are inherently intermittent (solar, wind, etc.) into the electric grid, though major advances in cost, cycle life, and safety are necessary to have a global impact on the energy landscape. Both aluminium (Al) and zinc (Zn) metals are earth abundant, low-cost, safe, and exhibit high coulombic capacities, which make them promising electrode materials for “beyond lithium-ion” battery chemistries. However, the electrochemical feasibility and charge storage mechanisms of alternative Al and …

Heavy Truck Collision With Bridge Piers, Ran Cao

Dissertations and Theses

Based on bridge failure data compiled by the New York State Department of Transportation, collision, both caused by vessels and vehicles, is the second leading cause of bridge failures after hydraulic. The current AASHTO-LRFD (2017) specification recommends designing a bridge pier vulnerable to vehicular impacts for an equivalent static force of 2,670-kN (600 kips) applied in a horizontal plane at a distance of 1.5 m (5.0 feet) above the ground level. The vast majority of research studies on vehicular collision with bridge piers have been carried out with single-unit trucks, which are typically classified as medium-duty vehicles weighing about 89 …

Microfluidic Study Of Gravity-Driven Drainage And Coalescence Of Aqueous Two Dimensional Foams, Justin D. Heftel

Dissertations and Theses

Foams, a two-phase dispersion, are staples of the cosmetic, personal care, petroleum, pharmaceutical, and other industries. Central to these applications is the stability of the dispersion against separation. Foams break down by two mechanisms: the first is bubble coalescence, which is driven by the gravity drainage of the continuous phase. The drainage acts to push the bubbles against each other, and leads to the formation of thin lamellae, which break and cause the coalescence. The second is the mass transfer of the dispersed phase through the continuous phase, which is caused by the difference in pressures between the bubbles and …

Void Fraction Measurements In A Large (0.3 M) Diameter Bubble Column Using Wire Mesh Sensors And Pressure Transducers: Effect Of Spargers, Afolabi G. Ojo

Dissertations and Theses

The importance of the accurate temporal and spatial measurements of the two-phase flow parameters in bubble columns is very well known. The aim of this research work is to report the spatial measurements of the void fraction distribution in a 30 cm diameter cylindrical bubble column using Wire Mesh Sensor (WMS) tomography and Pressure Transducers. Pair of WMS sensors, with a 64×64 wire configuration of each sensor, were installed which are separated by a distance along the axis of the bubble column. Wire Mesh Sensors and PTs Data were collected for time-averaged and transient with a sampling frequency of 1000 …

Intensification Of Gas Absorption In A Downward Flow Microbubble Bioreactor, Manizheh Ansari

Dissertations and Theses

Bioreactors are of interest for value-upgrading of stranded or waste industrial gases, such as CO, CH₄, or syngas. Process economics requires reduction of reactor cost and size while maintaining high production rate via rapid delivery of gas feedstock to the liquid phase which in turn requires a high volumetric mass transfer rate (). One strategy to achieve this goal is to increase interfacial area density, a, to >3000 m² m^-3, while minimizing use of energy. Here we show a novel reactor column design that uses a micro-jet array to break feedstock at ambient pressure …

Effect Of Hypoxia On Spontaneous Neural Activity In The Cortex Of Neonate Mouse Pups, Krithikka Ravi Ms

Dissertations and Theses

Hypoxia caused by inadequate oxygenation has profound effects on the normal functioning of the brain in mammals. Acute or chronic hypoxic insults occur in the brain depending on the duration of hypoxic exposure. Hypoxia is known to occur in the human womb and exerts adverse effects on the developing fetus. Most of the ongoing research on hypoxia is performed on rodent brain slice taken from various brain regions using intracellular recording. Extensive work has been carried out to understand the effects of chronic hypoxia on the developing nervous system, specifically during intrauterine development. However, effects of acute hypoxia occurring perinatally, …

Unsupervised Feature Learning For Point Cloud By Contrasting And Clustering With Graph Convolutional Neural Network, Ling Zhang

Dissertations and Theses

Recently, deep graph neural networks (GNNs) have attracted significant attention for point cloud understanding tasks, including classification, segmentation, and detection. However, the training of such deep networks still requires a large amount of annotated data, which is both expensive and time-consuming. To alleviate the cost of collecting and annotating large-scale point cloud datasets, we propose an unsupervised learning approach to learn features from unlabeled point cloud ”3D object” dataset by using part contrasting and object clustering with GNNs. In the contrast learning step, all the samples in the 3D object dataset are cut into two parts and put into a …

Understanding And Modeling Taxi Demand Using Time Series Models, Sabiheh Faghih

Dissertations and Theses

The spatio-temporal variations in demand for transportation, particularly taxis, are impacted by various factors such as commuting, weather, road work and closures, disruption in transit services, etc. Identifying the factors that influence taxi demand and understanding its dynamic provide planners with the information necessary to improve the transportation systems and also help drivers to reduce their vacant time.

This dissertation focuses on important factors affecting the demand. In the beginning, the impact of price changes on the demand is studied. Chapter One discusses how the seasonal effects and trends are removed from the demand, and then price elasticity for demand …

Improving Retrievals Of Crop Vegetation Parameters From Remote Sensing Data, Nathaniel Levitan

Dissertations and Theses

Agricultural systems are difficult to model because crop growth is driven by the strongly nonlinear interaction of Genotype x Environment x Management (G x E x M) factors. Due to the nonlinearity in the interaction of these factors, the amount of data necessary to develop and utilize models to accurately predict the performance of agricultural systems at an operational scale is large. Satellite remote sensing provides the potential to vastly increase the amount of data available for modelling agricultural systems as a result of its high revisit time and spatial coverage. Unfortunately, there have been significant difficulties in deploying remote …

Hydroclimate Drivers And Atmospheric Dynamics Of Floods, Nasser Najibi

Dissertations and Theses

Our preliminary survey showed that most of the recent flood-related studies did not formally explain the physical mechanisms of long-duration and large-peak flood events that can evoke substantial damages to properties and infrastructure systems. These studies also fell short of fully assessing the interactions of coupled ocean-atmosphere and land dynamics which are capable of forcing substantial changes to the flood attributes by governing the exceeding surface flow regimes and moisture source-sink relationships at the spatiotemporal scales important for risk management. This dissertation advances the understanding of the variability in flood duration, peak, volume, and timing at the regional to the …

Collective Behavior Of Drosophila Melanogaster Neural Progenitor And Imaginal Disc Cells Within Controlled Microenvironments, Caroline D. Pena

Dissertations and Theses

Regenerative therapies for the damaged visual system have introduced stem-derived cells to recapitulate developmental processes and initiate functional regeneration in different components of the eye. The developing visual system in Drosophila Melanogaster offers a model in which to analyze the associated processes in retinogenesis. The optic nerve is critical to vision and is developmentally preceded in Drosophila by a structure called the Optic Stalk (OS). Collective migration of neural and retinal progenitor cells (RPCs) from the developing brain lobes (DBL) to the Imaginal Disc (ID), through the OS, is a fundamental part of regenerative strategies in retina. Developmental signals governing …

Integrating Multi-Source Weather Data For Deep Learning, Haidar A. Alanbari Mr

Dissertations and Theses

Big Data has been playing a major role in the domain of Deep Learning applications as many companies and institutions continue to find solutions and extract certain trends in fields of climate change, weather forecasting and meteorology. This project extracts weather events data from multiple data sources that are supported by National Centers for Environmental information (NCEI) [1] and Amazon Web Services (AWS) [2]. Data sources include Next-Generation NEXRAD [3] Doppler radar reflectivity, GOES-16 [4] multi-channel satellite imagery and NCEI [1] storm events. Then, it integrates and refines data in proper formats to be fed to the open-source Detectron [5] …

Software Defined Radio For Hybrid Beamforming Applications, Jianyet Lee

Dissertations and Theses

Beamforming techniques have been deployed in both licensed networks such as LTE network and unlicensed network such as IEEE802.11ac WiFi. The scope of work for this thesis is to leverage the benefits of beamforming techniques and software defined radio platform in developing a fully functioning LTE testbed. The testbed can be further developed to specific application for drone-to-drone or D2D communication independent of intervention from base stations. Applying beamforming techniques to devices such as drones can solve poor quality signal detection at the receivers due to the interference signals generated by other devices in the attempt to communicate with the …