Engineering Commons^™

Pervasive Spectrum Sharing For Improved Wireless Experience, Mostafizur Rahman

Electronic Theses and Dissertations, 2020-2023

Spectrum sharing among cellular users has been a promising approach to attain better efficiency in the use of the limited spectral bands. The existing dynamic spectrum access techniques include sharing of the licensed spectrum bands by allowing other 'secondary' users to use the bands if the licensee 'primary' user is idle. This primary-secondary spectrum sharing is limited in terms of design space, and may not be sufficient to meet the ever-increasing demand of connectivity and high signal quality to improve the end-users' wireless experience. The next step to increase spectrum efficiency is to design markets where sharing takes place pervasively …

Bias And Sensitivity Of Nonlinear Models For Seismic Response Of Ordinary Standard Bridges, Andres Rodriguez Caballero

Electronic Theses and Dissertations, 2020-2023

The implementation of nonlinear structural analysis under large deformation demands has enabled more realistic response prediction in comparison with the classical linear approaches. However, the sensitivity to modeling assumptions, element and material formulations, implementations, and parameter selection may lead to unreliable results. While previous works have led to a better understanding of how to best model nonlinear static responses of bridge components and systems, the introduction of dynamic loads and the corresponding material hysteresis presents an additional source of variability in the nonlinear responses. The current research involves the analysis of two ordinary standard bridges in California under seismic load …

Smartphone Sensor-Based Pedestrian Activity Recognition For P2v Communication And Warning System, Dhrubo Hasan Chowdhury

Electronic Theses and Dissertations, 2020-2023

The ubiquity of smartphones has made a remarkable influence on everyone's day to day life. Variety of useful built-in sensors provide smartphones with a convenient floor for data collection and analysis. Application development based on the user's location and movement is not a difficult task nowadays. But injuries and deaths due to smartphone-distracted movement on roadways is on the increase. This study explores the capabilities of smartphone inertial sensors for pedestrian activity recognition. Smartphone distracted movements can be predicted from the associated pedestrian's posture, thus inertial sensors can provide effective solution for this specific task. Volunteers were asked to perform …

Tip Clearance Effect On Convective Heat Transfer In Micro Scale Pin Fins, Hanieh Tabkhivayghan

Electronic Theses and Dissertations, 2020-2023

Fluid flow and local heat transfer in a microchannel with single and array of pin fins have been studied. For the single pin fin case, a microchannel with a 150-µm diameter pin fin with a tip clearance was experimentally and numerically studied for three Reynolds numbers in laminar regime. Tip clearances of 0, 30, 45 and 100 µm in a 200-µm high microchannel. Experimental and numerical local temperatures and the corresponding Nusselt numbers along the centerline of the pin fin were presented and discussed. Local temperatures were measured on top of the heater surface and downstream the pin fin through …

Seismocardiography - Genesis, And Utilization Of Machine Learning For Variability Reduction And Improved Cardiac Health Monitoring, Peshala Thibbotuwawa Gamage

Electronic Theses and Dissertations, 2020-2023

Seismocardiography (SCG) is the measured chest surface vibrations resulting from cardiac activity. Although SCG can contain information that correlate with cardiac health, its utility may be limited by lack of understanding of the signal genesis and a variability that can mask subtle SCG changes. The current research utilized medical imaging reconstruction and finite element method (FEM) to simulate SCG by modeling the propagation of myocardial movements to the chest surface. FEM analysis provided a link between myocardial movements and the SCG signals measured at the chest surface and suggested that myocardial movement is a primary source of SCG. Increased understanding …

A Facile, Fast, And Low-Cost Method For Fabrication Of Micro/Nano-Textured Superhydrophobic Surfaces, Amir Esmaeili, Noshin Mir, Reza Mohammadi

Graduate Research Posters

Background

Alkyl ketene dimer (AKD) is frequently used in paper industry as an inexpensive sizing agent. The formation of a fractal structure after curing the solidified AKD for an extra-long time (4 - 6 days) results in superhydrophobicity. In this study, a facile and low-cost method was utilized to turn AKD’s surface superhydrophobic in a very short period of time.

Method

We fabricated a superhydrophobic layer by dipping glass and paper substrates in molten AKD and then treating them with ethanol after solidification. The samples were characterized by X-ray diffraction, Scanning electron microscopy, Fourier transform-infrared spectroscopy, X-ray photoelectron spectroscopy, Confocal …

Dose Deposition And Electrostatic Charging Of Kapton Films Irradiated With Electrons, Youssef Abouhussien, Gennady Miloshevsky

Graduate Research Posters

Kapton films are widely utilized in harsh radiation environments where radiation resistant insulating materials are required. For space applications, Kapton polymers are used on satellites as substrates for solar arrays and outer layers of thermal systems. Kapton is also used in nuclear power plants as wire insulation. Kapton materials can be exposed in nuclear reactors to a reactive chemical environment in addition to severe radiation. It is of utmost important to understand how Kapton materials behave under high irradiation conditions and mitigate radiation damage effects. High-energy electrons can deposit ionizing dose and electric charge deeply inside Kapton materials. The charge …

Photolithographic Micropatterning Of Organic, Flexible Biomaterials And Its Applications, Sayantan Pradhan, Sayantan Pradhan, Meng Xu, Vamsi K. Yadavalli

Graduate Research Posters

A current trend in biodevices has involved a shift from traditional rigid platforms to flexible and stretchable formats. These flexible devices are expected to have a significant impact on future healthcare, disease diagnostics and therapeutics. However, the fabrication of such flexible devices has been limited by the choice of materials. Biomimetic composites of naturally derived and synthetic polymers provide exciting opportunities to develop mechanically flexible, physiologically compliant, and degradable bioelectronic systems. Advantages include the ability to provide conformal contact at non-planar biointerfaces, being able to be degraded at controllable rate, and invoking minimal reactions within the body. These factors present …

Jxb Force Effects On Beryllium Melt Splashing In Fusion Devices, Cheng Zhang, Gennady Miloshevsky

Graduate Research Posters

Instability and disruption of high-temperature plasma in fusion devices may result in the edge-localized modes (ELMs) and lead to melting of plasma facing components (PFCs) causing their damage. Beryllium (Be) is used as a first wall for PFCs due to its low density, high strength, and high thermal conductivity. However, melting of Be on the surface of first wall is of a great concern as splashing of a molten Be layer will result in the plasma contamination and termination of fusion reaction. Therefore, it is important to understand the physics mechanisms characterizing the splashing of Be from a pool under …

Evaluating The Effectiveness Of Shielding Material, Vehicle Shape And Astronaut Position For Deep Space Travel, Daniel Bond, Braden Goddard, Robert Singleterry, Sama Bilbao Y Leon

Graduate Research Posters

Background: As future crewed, deep space missions are being planned, it is important to assess how spacecraft design can be used to minimize radiation exposure. Collectively with shielding material, vehicle shape and astronaut position must be used to protect astronauts from the two primary sources of space radiation: Galactic Cosmic Rays (GCRs) and Solar Particle Events (SPEs).

Methods: The On-Line Tool for the Assessment of Radiation in Space (OLTARIS) version 4.1 analysis package is used to evaluate and analyze this detailed radiation field. Developed by the National Aeronautics and Space Administration's (NASA) Langley Research Center, the tool enables engineering and …

Elastic Foundations As Heterogeneous Adventitial Boundary Condition For The Assessment Of Aortic Wall And Peri-Aortic Stiffness From Dense-Mri Data Using Inverse Fem Approach, Johane H. Bracamonte, John S. Wilson, Joao S. Soares

Graduate Research Posters

Background: The establishment of in vivo, patient-specific, and regionally resolved techniques to quantify aortic properties is key for improving risk assessment in clinical practice and scientific understanding of cardiovascular growth and remodeling. Many in vivo studies quantify vascular stiffness using Pulse Wave Velocity. This method provides an averaged measure of stiffness for the entire aorta, ignoring variations in wall stiffness and boundary conditions. Previous studies using Displacement Encoding with Stimulated Echoes Magnetic Resonance Imaging (DENSE-MRI) suggested that the infrarenal abdominal aorta (IAA) deforms heterogeneously throughout the cardiac cycle.

Method: Herein, we hypothesize that the aortic wall strain heterogeneity is driven …

Spatio-Temporal Evolution Of Warm Dense Plasmas: Molecular Dynamics Modeling, Harrison Wenzel, Gennady Miloshevsky

Graduate Research Posters

SPATIO-TEMPORAL EVOLUTION OF WARM DENSE PLASMAS: MOLECULAR

DYNAMICS MODELING Cole Wenzel and Gennady Miloshevsky

Virginia Commonwealth University, Department of Mechanical and Nuclear Engineering, 401

West Main St, Richmond, VA 23284-3015

The exo-atmospheric detonation of nuclear device would be of great impact on the material integrity of orbiting satellites. The spectral energy distribution of high intensity X-ray flux, ~10 28 -10 35 photons/(cm 2 ∙s), originating from a nuclear blast is described by the Planck's blackbody function with the temperature from 0.1 keV to 10 keV. Particular damage would occur to the multi-layered, solar cell panels of satellites. However, the X-ray …

Evaluation Of Object Attributes To Study Speed-Accuracy Trade-Off Of Gloves Using Iso 9241-411 Standard, Isha Gaut

Graduate Theses, Dissertations, and Problem Reports (ETD)

Selection of appropriate gloves plays an important role in the overall comfort and productivity of workers. Currently, there are no standards and/or guidelines available to systematically evaluate the glove performance based on speed-accuracy trade-off. The ISO 9241-411 standard which is based on Fitts’ Law has been extensively used in the literature to measure speed-accuracy trade-off in terms of throughput in the virtual environments. This study was aimed at developing guidelines for implementing ISO 9241-411 standard in the physical environment so that it can be used to estimate (and compare) throughputs of safety gloves. Specifically, the various physical attributes of objects …

Literature Review On Modeling Of Density Difference Pumping Strategy For Geothermal Applications, Lucas A. Ware

Graduate Theses, Dissertations, and Problem Reports (ETD)

The utilization of geothermal ground heat sources has been demonstrated at both large and small scales across the world. However, methods of extraction of the hot working fluids are often a source of energy inefficiency and high capital expense. Current techniques to extract geothermal fluids rely on mechanically and electrically driven down-hole components that require maintenance on a regular basis. In providing a solution, one approach that reduces complexity, decreases maintenance, and allows access to fluids at greater depth is an airlift approach. The airlift approach relies on injection of gas at a depth within a geothermal well to lift …

Comparison Of Condensation Nuclei Counter And Controlled Negative Pressure Methods Under Different Environmental Conditions Tested With A Mannequin And Human Subjects, Olanrewaju John Fadairo

Graduate Theses, Dissertations, and Problem Reports (ETD)

Continuing concern about exposure to respiratory hazards at various workplaces and prevalent pandemics such as H1N1/09 influenza and COVID-19, have necessitated a need for more research regarding respirators. Quantitative fit testing (QNFT) is a critical component of an OSHA compliant respiratory protection program. QNFTs are often performed in environments where temperature and relative humidity (RH) vary. However, no study has investigated the possible effects of these parameters on penetration and QNFT results.

This comparative study utilized condensation nuclei counter (CNC) and controlled negative pressure (CNP) methods to quantitatively determine simulated mannequin fit factors (SMFFs) and human fit factor (HFFs) using …

Dynamics Within A Tunable Harmonic/Quartic Waveguide, Rudolph N. Kohn Jr., James A. Stickney

Space Dynamics Laboratory Publications

We present an analytical solution to the dynamics of a noninteracting cloud of thermal atoms in a cigar-shaped harmonic trap with a quartic perturbation along the axial direction. We calculate the first and second moments of position, which are sufficient to characterize the trap. The dynamics of the thermal cloud differ notably from those of a single particle, with an offset to the oscillation frequency that persists even as the oscillation amplitude approaches zero. We also present some numerical results that describe the effects of time-of-flight on the behavior of the cloud in order to better understand the results of …

Implementation And Improvement Of Common Text-Independent Speaker Identification, Yunlong Wang

Graduate Research Theses & Dissertations

The purpose of this thesis is to improve and implement the existing speaker recognition system. The proposed system will be cooperate with automatic speech recognition for automatically generating a script file for a recorded dialog file. Today's speech recognition technology has been widely used in many application areas; however, speaker recognition technology needs to be improved for such a purpose in noisy environment. In the process of a recorded file including multi-person conversation, manual speaker identification is often required. The proposed technique can automatically find the ID of each speaker and save manpower. It has potential applications in many other …

Examination Of The Adhesiveness Of The Nanotube Layer On Anodized Commercially Pure Titanium Samples Using The Micro-Limiting Dome Height Test And The Tensile Test., Joshua Manohar Chinthapalli

Graduate Research Theses & Dissertations

Titanium oxide (TiO2) nanotube is one of the most extensively studied nanotubes due to its wide applications in electronics and medical fields. In this study, we used electrochemical anodization to create nanotubes on commercially pure titanium (Cp-Ti) samples and examined the adhesiveness of the nanotube layer on the sample surface. Particularly we conducted micro-limiting dome height (µLDH) tests on anodized Cp-Ti foils of 38 µm thickness and 4 mm diameter at room temperature, 100℃, and 200℃. We also conducted tensile tests on standard tensile specimens of anodized Cp-Ti plate at room temperature, and 200℃. The Hitachi S-4500 Field Emission Scanning …

Surface Modification Of Titanium For Orthopedic And Drug Delivery Applications, Prantik Roy Chowdhury

Graduate Research Theses & Dissertations

Titanium is one of the most attractive metal used in orthopedic and drug delivery applications because of its excellent mechanical properties, biocompatibility and high corrosion resistance. However, due to its bio-inertness, fibrous tissue forms between the bone and implant which causes loosening of implant. Surface modification can play an important role to enhance interaction between implant and the surrounding tissues which reduces the implant failure. The aim of this study is to a) incorporate magnesium (Mg) into modified titanium surface by different deposition methods for bone-implant interaction, b) modify the surface of titanium by alkali treatment, and c) investigate the …

Model-Based Network Reconstruction From Cascade Dynamics, Katherine Irena Chwistek

Graduate Research Theses & Dissertations

Network representation provides a natural framework for the study of real world complex systems. From social networks and animal groups to interneuronal communications and power grid systems, complex patterns of interaction can be captured and modeled using networks in a simple mathematical form. In many cases, however, a faithful network representation of the system is not readily available. For this reason, network reconstruction has become a growing topic of interest in recent years, the goal of which is to discover the hidden interaction patterns among individuals by fitting input-output data from multiple experiments to candidate network topologies.

During a cascade, …

Cobalt Partitioning And Solubility In Low-Temperature Carbonate-Hydrothermal Systems, Seth Kurtis Coursey

Graduate Research Theses & Dissertations

Cobalt mineralization has been documented in low temperature Mississippi Valley-type (MVT) deposits in southeast Missouri. Lead and zinc are the most economically important metals in these deposits and are contained within galena (PbS) and sphalerite (ZnS), respectively. Cobalt is also mined in some of the deposits with cobalt-bearing ores, e.g., siegenite ((Ni,Co)3S4) and fletcherite (Cu,(Ni,Co)2S4), occurring stratigraphically below main-stage galena and sphalerite. The hydrothermal fluids responsible for cobalt mineralization are thought to be chemically distinct from the predominant MVT ore-bearing fluids and represent a distinct mineralizing event. Cobalt is likely transported as CoCl2 in hydrothermal fluids and sourced from structures …

Physical And Mechanical Properteis Of Magnesium-Incorporated Bone Substitute Materials, Sarah E. Fleck

Graduate Research Theses & Dissertations

Calcium phosphate (CaP) ceramics have become popular as bone substitutes due to their biocompatibility and similarity to natural bone. Although they are widely used, the mechanical and biological properties of these CaP ceramics can be improved by various methods such as combining them with polymers or ionic substitution in their crystal structure. In current research, we have used carboxymethyl cellulose (CMC) and magnesium (Mg) to modify the physical and mechanical properties of CaP. CMC is a derivative of cellulose which is hydrophilic, biodegradable, and biocompatible. Presence of Mg, a trace element naturally found in the body, is linked to bone …

Particle Injection Simulation On Cold Spray Technology, Christopher A. Santini

Electronic Theses and Dissertations

Computational Fluid Dynamics (CFD) is a useful tool when it comes to research in the fields of Aerodynamics, Turbomachinery, and is used in several other fields of research. CFD is an important tool in the engineering industry because it allows for understanding and evaluation of a new design, this can lead to advancements in developing a more efficient and effective design. This tool helps in the understanding of the flow phenomena and how it can interact with its surroundings. One of the main reasons in the use of CFD is to reduce the cost of testing a design by running …

Computational Intelligence Approaches For Energy Optimization In Microgrids, Tamal Roy

Electronic Theses and Dissertations

The future electrical system termed as smart grid represents a significant paradigm shift for power industry. Nowadays, microgrids are becoming smarter with the integration of renewable energy resources (RESs) , diesel generators , energy storage systems (ESS), and plug-in electric vehicles (PEV or EV) . However, these integration bring with new challenges for intelligent management systems. The classical power generation approaches can no longer be applied to a microgrid with unpredictable renewable energy resources. To relive these problem, a proper power system optimization and a suitable coordination strategy are needed to balance the supply and demand. This thesis presents three …

Finding A Single Equation To Represent Urea Evaporation, Sublimation, And Decomposition In Selective Catalytic Reduction Systems, Noah Hertzler

Senior Honors Theses

Aqueous Urea used in Selective Catalytic Reduction (SCR) Systems undergoes three sequential processes that result in ammonia being produced to reduce harmful NOx emissions: Water evaporation, Urea sublimation, and Urea decomposition into ammonia and isocyanic acid. While these phases can be simplified by modeling the Urea as pure water, accuracy is sacrificed to do so. In order to make SCR modelling both accurate and simple, this project set out to find an equation that could represent all three processes. Simulations were run in ANSYS and Particle to generate a set of data, then an empirical equation was created to model …

Confinement Of Monolithic Stationary Phases In Targeted Regions Of 3d-Printed Titanium Devices Using Thermal Polymerization, Marta Passamonti, Ischa L. Bremer, Suhas H. Nawada, Sinead A. Currivan, Andrea F.G. Gargano, Peter J. Schoenmakers

Articles

Abstract

In this study, we have prepared thermally initiated polymeric monolithic stationary phases within discrete regions of 3D-printed titanium devices. The devices were created with controllable hot and cold regions. The monolithic stationary phases were first locally created in capillaries inserted into the channels of the titanium devices. The homogeneity of the monolith structure and the interface length were studied by scanning a capacitively coupled conductivity contactless detector (C4D) along the length of the capillary. Homogeneous monolithic structures could be obtained within a titanium device equipped with a hot and cold jacket connected to two water baths. The confinement method …

Utility-Scale Solar Pv Performance Enhancements Through System Level Modifications, Andrew D. S. Glick, Naseem Ali, Juliaan Bossuyt, Marc Calaf, Raúl Bayoán Cal

Mechanical and Materials Engineering Faculty Publications and Presentations

Performance of solar PV diminishes with the increase in temperature of the solar modules. Therefore, to further facilitate the reduction in cost of photovoltaic energy, new approaches to limit module temperature increase in natural ambient conditions should be explored. Thus far only approaches based at the individual panel level have been investigated, while the more complex, systems approach remains unexplored. Here, we perform the first wind tunnel scaled solar farm experiments to investigate the potential for temperature reduction through system-level flow enhancement. The percentage of solar irradiance converted into electric power depends upon module efficiency, typically less than 20%. The …

Wind Power Forecasting Methods Based On Deep Learning: A Survey, Xing Deng, Haijian Shao, Chunlong Hu, Dengbiao Jiang, Yingtao Jiang

Electrical & Computer Engineering Faculty Research

Accurate wind power forecasting in wind farm can effectively reduce the enormous impact on grid operation safety when high permeability intermittent power supply is connected to the power grid. Aiming to provide reference strategies for relevant researchers as well as practical applications, this paper attempts to provide the literature investigation and methods analysis of deep learning, enforcement learning and transfer learning in wind speed and wind power forecasting modeling. Usually, wind speed and wind power forecasting around a wind farm requires the calculation of the next moment of the definite state, which is usually achieved based on the state of …

Distributed Machine Learning Approach To Fast Frequency Response-Based Inertia Estimation In Low Inertia Grids, Abodh Poudyal

Electronic Theses and Dissertations

Recent updates to the IEEE 1547-2018 standard allow active participation of distributed energy resources (DERs) in power grid services with the goal of increased grid reliability and resiliency. With the rapid growth of DERs towards a low inertia converter-dominated grid, the DERs can provide fast frequency response (FFR) services that can quickly counteract the change in system frequency through inertial support. However, in low voltage grids, frequency and voltage face dynamics coupling due to a high resistance to reactance ratio and cannot be controlled separately as in the bulk electric grid. Due to the coupling effect, the control of one …

A Probabilistic Machine Learning Framework For Cloud Resource Selection On The Cloud, Syeduzzaman Khan

University of the Pacific Theses and Dissertations

The execution of the scientific applications on the Cloud comes with great flexibility, scalability, cost-effectiveness, and substantial computing power. Market-leading Cloud service providers such as Amazon Web service (AWS), Azure, Google Cloud Platform (GCP) offer various general purposes, memory-intensive, and compute-intensive Cloud instances for the execution of scientific applications. The scientific community, especially small research institutions and undergraduate universities, face many hurdles while conducting high-performance computing research in the absence of large dedicated clusters. The Cloud provides a lucrative alternative to dedicated clusters, however a wide range of Cloud computing choices makes the instance selection for the end-users. This thesis …