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Articles 1261 - 1290 of 4692

Full-Text Articles in Engineering

Fluid-Wall Interactions In Pseudopotential Lattice Boltzmann Models, Cheng Peng, Luis F. Ayala, Orlando M. Ayala Jan 2021

Fluid-Wall Interactions In Pseudopotential Lattice Boltzmann Models, Cheng Peng, Luis F. Ayala, Orlando M. Ayala

Engineering Technology Faculty Publications

Designing proper fluid-wall interaction forces to achieve proper wetting conditions is an important area of interest in pseudopotential lattice Boltzmann models. In this paper, we propose a modified fluid-wall interaction force that applies for pseudopotential models of both single-component fluids and partially miscible multicomponent fluids, such as hydrocarbon mixtures. A reliable correlation that predicts the resulting liquid contact angle on a flat solid surface is also proposed. This correlation works well over a wide variety of pseudopotential lattice Boltzmann models and thermodynamic conditions.

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Let's Collaborate! The Importance Of Cybersecurity Pathways And Their Accessibility, Vukica Jovanovic, Otilia Popescu, Murat Kuzlu, Petros Katsioloudis Jan 2021

Let's Collaborate! The Importance Of Cybersecurity Pathways And Their Accessibility, Vukica Jovanovic, Otilia Popescu, Murat Kuzlu, Petros Katsioloudis

Engineering Technology Faculty Publications

[Introduction] I am very passionate about inspiring a new generation of the STEM workforce. Going through the engineering pathway myself since 9th grade, I have seen the value of technical education and early career choice. In high school, I learned so much about math and science, but also about the technical and applied aspects of STEM professions. I had one apprenticeship in electrical power and aluminum mill companies where I explored how the concepts from the classes convey to the real world. It was so much easier to learn all the equations and different aspects of technology from the textbook …

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Investigation Of Anaerobic Digestion Of The Aqueous Phase From Hydrothermal Carbonization Of Mixed Municipal Solid Waste, Kameron J. Adams, Ben Stuart, Sandeep Kumar Jan 2021

Investigation Of Anaerobic Digestion Of The Aqueous Phase From Hydrothermal Carbonization Of Mixed Municipal Solid Waste, Kameron J. Adams, Ben Stuart, Sandeep Kumar

Civil & Environmental Engineering Faculty Publications

In 2017, the United States Environmental Protection Agency (EPA) reported that Americans generated over 268 million tons of municipal solid waste (MSW). The majority (52%) of this waste ends up in landfills, which are the third largest source of anthropogenic methane emissions. Improvements in terms of waste management and energy production could be solved by integrating MSW processing with hydrothermal carbonization (HTC) and anaerobic digestion (AD) for converting organic carbon of MSW to fuels. The objectives of this study were to (a) investigate HTC experiments at varying temperatures and residence times (b) evaluate aqueous phase and solids properties, and (c) …

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Low-Temperature Gas Plasma Combined With Antibiotics For The Reduction Of Methicillin-Resistant Staphylococcus Aureus Biofilm Both In Vitro And In Vivo, Li Guo, Lu Yang, Yu Qi, Gulimire Niyazi, Jianbao Zheng, Ruobing Xu, Xusong Chen, Jingye Zhang, Wang Xi, Dingxin Liu, Xiaohua Wang, Hailan Chen, Michael G. Kong Jan 2021

Low-Temperature Gas Plasma Combined With Antibiotics For The Reduction Of Methicillin-Resistant Staphylococcus Aureus Biofilm Both In Vitro And In Vivo, Li Guo, Lu Yang, Yu Qi, Gulimire Niyazi, Jianbao Zheng, Ruobing Xu, Xusong Chen, Jingye Zhang, Wang Xi, Dingxin Liu, Xiaohua Wang, Hailan Chen, Michael G. Kong

Electrical & Computer Engineering Faculty Publications

Biofilm infections in wounds seriously delay the healing process, and methicillin-resistant Staphylococcus aureus is a major cause of wound infections. In addition to inactivating micro-organisms, low-temperature gas plasma can restore the sensitivity of pathogenic microbes to antibiotics. However, the combined treatment has not been applied to infectious diseases. In this study, low-temperature gas plasma treatment promoted the effects of different antibiotics on the reduction of S. aureus biofilms in vitro. Low-temperature gas plasma combined with rifampicin also effectively reduced the S. aureus cells in biofilms in the murine wound infection model. The blood and histochemical analysis demonstrated the biosafety of …

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Covid-19 And Biocybersecurity's Increasing Role On Defending Forward, Xavier Palmer, Lucas N. Potter, Saltuk Karahan Jan 2021

Covid-19 And Biocybersecurity's Increasing Role On Defending Forward, Xavier Palmer, Lucas N. Potter, Saltuk Karahan

Electrical & Computer Engineering Faculty Publications

The evolving nature of warfare has been changing with cybersecurity and the use of advanced biotechnology in each aspect of the society is expanding and overlapping with the cyberworld. This intersection, which has been described as “biocybersecurity” (BCS), can become a major front of the 21st-century conflicts. There are three lines of BCS which make it a critical component of overall cybersecurity: (1) cyber operations within the area of BCS have life threatening consequences to a greater extent than other cyber operations, (2) the breach in health-related personal data is a significant tool for fatal attacks, and (3) health-related misinformation …

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Ship Deck Segmentation In Engineering Document Using Generative Adversarial Networks, Mohammad Shahab Uddin, Raphael Pamie-George, Daron Wilkins, Andres Sousa Poza, Mustafa Canan, Samuel Kovacic, Jiang Li Jan 2021

Ship Deck Segmentation In Engineering Document Using Generative Adversarial Networks, Mohammad Shahab Uddin, Raphael Pamie-George, Daron Wilkins, Andres Sousa Poza, Mustafa Canan, Samuel Kovacic, Jiang Li

Engineering Management & Systems Engineering Faculty Publications

Generative adversarial networks (GANs) have become very popular in recent years. GANs have proved to be successful in different computer vision tasks including image-translation, image super-resolution etc. In this paper, we have used GAN models for ship deck segmentation. We have used 2D scanned raster images of ship decks provided by US Navy Military Sealift Command (MSC) to extract necessary information including ship walls, objects etc. Our segmentation results will be helpful to get vector and 3D image of a ship that can be later used for maintenance of the ship. We applied the trained models to engineering documents provided …

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Conceptual Development Of A Probabilistic Graphical Framework For Assessing Port Resilience, Katherine Smith, Rafael Diaz, Yuzhong Shen, Francesco Longo Jan 2021

Conceptual Development Of A Probabilistic Graphical Framework For Assessing Port Resilience, Katherine Smith, Rafael Diaz, Yuzhong Shen, Francesco Longo

VMASC Publications

Technological advances such as cyber physical systems and autonomous vehicles combined with increased disruptions including the Covid-19 pandemic and coastal natural disasters have heightened the importance of port risk analysis methodologies and frameworks that can accurately quantify and optimize resilience. This work presents the conceptual development of a novel combination of analysis methodologies linking a probabilistic graphic approach on a network of risk events with a functional dependency approach on a system network. Key advantages of these two methodologies are the ability to model and learn causal interactions rather than simply correlations and a high level of computational efficiency. This …

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Development And Characterization Of Nb₃N/Al₂0₃ Superconducting Multilayers For Particle Accelerators, Chris Sundahl, Junki Makita, Paul B. Welander, Yi-Feng Su, Fumitake Kametani, Lin Xie, Huimin Zhang, Lian Li, Alex Gurevich, Chang-Beom Eom Jan 2021

Development And Characterization Of Nb₃N/Al₂0₃ Superconducting Multilayers For Particle Accelerators, Chris Sundahl, Junki Makita, Paul B. Welander, Yi-Feng Su, Fumitake Kametani, Lin Xie, Huimin Zhang, Lian Li, Alex Gurevich, Chang-Beom Eom

Physics Faculty Publications

Superconducting radio-frequency (SRF) resonator cavities provide extremely high quality factors > 1010 at 1-2 GHz and 2 K in large linear accelerators of high-energy particles. The maximum accelerating field of SRF cavities is limited by penetration of vortices into the superconductor. Present state-of-the-art Nb cavities can withstand up to 50 MV/m accelerating gradients and magnetic fields of 200-240 mT which destroy the low-dissipative Meissner state. Achieving higher accelerating gradients requires superconductors with higher thermodynamic critical fields, of which Nb3Sn has emerged as a leading material for the next generation accelerators. To overcome the problem of low vortex penetration …

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One-Dimensional Lateral Force Anisotropy At The Atomic Scale In Sliding Single Molecules On A Surface, Yuan Zhang, Daniel J. Trainer, Badri Narayanan, Yang Li, Anh T. Ngo, Sushila Khadka, Arnab Neogi, Brandon Fisher, Larry A. Curtiss, Subramanian K.R.S. Sankaranarayanan, Saw Wai Hla Jan 2021

One-Dimensional Lateral Force Anisotropy At The Atomic Scale In Sliding Single Molecules On A Surface, Yuan Zhang, Daniel J. Trainer, Badri Narayanan, Yang Li, Anh T. Ngo, Sushila Khadka, Arnab Neogi, Brandon Fisher, Larry A. Curtiss, Subramanian K.R.S. Sankaranarayanan, Saw Wai Hla

Physics Faculty Publications

Using a q+ atomic force microscopy at low temperature, a sexiphenyl molecule is slid across an atomically flat Ag(111) surface along the direction parallel to its molecular axis and sideways to the axis. Despite identical contact area and underlying surface geometry, the lateral force required to move the molecule in the direction parallel to its molecular axis is found to be about half of that required to move it sideways. The origin of the lateral force anisotropy observed here is traced to the one-dimensional shape of the molecule, which is further confirmed by molecular dynamics simulations. We also demonstrate that …

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Inverted Geometry Ceramic Insulators In High Voltage Dc Electron Guns For Accelerators, C. Hernandez-Garcia, G. Palacios-Serrano, P. Adderley, D. Bullard, J. Grames, Md. Abdullah Mamun, M. Poelker, M. Stutzman, R. Suleiman, Y. Wang, S.A.K. Wijethunga Jan 2021

Inverted Geometry Ceramic Insulators In High Voltage Dc Electron Guns For Accelerators, C. Hernandez-Garcia, G. Palacios-Serrano, P. Adderley, D. Bullard, J. Grames, Md. Abdullah Mamun, M. Poelker, M. Stutzman, R. Suleiman, Y. Wang, S.A.K. Wijethunga

Physics Faculty Publications

A direct current (dc) high voltage photo-emission electron gun operating at 130 kV is utilized at the Jefferson Lab (JLab) Continuous Electron Beam Accelerator Facility to generate spin-polarized electrons for nuclear physics experiments. Over the past decade, JLab has tested and implemented inverted-geometry ceramic insulators in photoguns, connecting the cathode electrode in vacuum to the high voltage power supply using commercial high voltage cables. The results of those tests showed that breakdown voltage was increased using triple-point shielding electrodes and bulk-doped insulators that allow charge drainage. This contribution describes ongoing work to develop a robust insulatorcable connector for reliably applying …

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Magnetic Field Sensors For Detection Of Trapped Flux In Superconducting Radio Frequency Cavities, Ishwari Prasad Parajuli, Gianluigi Ciovati, Jean R. Delayen Jan 2021

Magnetic Field Sensors For Detection Of Trapped Flux In Superconducting Radio Frequency Cavities, Ishwari Prasad Parajuli, Gianluigi Ciovati, Jean R. Delayen

Physics Faculty Publications

Superconducting radio frequency (SRF) cavities are fundamental building blocks of modern particle accelerators. They operate at liquid helium temperatures (2–4 K) to achieve very high quality factors (1010–1011). Trapping of magnetic flux within the superconductor is a significant contribution to the residual RF losses, which limit the achievable quality factor. Suitable diagnostic tools are in high demand to understand the mechanisms of flux trapping in technical superconductors, and the fundamental components of such diagnostic tools are magnetic field sensors. We have studied the performance of commercially available Hall probes, anisotropic magnetoresistive sensors, and flux-gate magnetometers with …

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Generation Of Excited Species In A Streamer Discharge, Shirshak K. Dhali Jan 2021

Generation Of Excited Species In A Streamer Discharge, Shirshak K. Dhali

Electrical & Computer Engineering Faculty Publications

At or near atmospheric pressure, most transient discharges, particularly in molecular gases or gas mixture containing molecular gases, result in a space charge dominated transport called a streamer discharge. The excited species generation in such discharges forms the basis for plasma chemistry in most technological applications. In this paper, we simulate the propagation of streamers in atmospheric pressure N2 to understand the energy partitioning in the formation of various excited species and compare the results to a uniform Townsend discharge. The model is fully two-dimensional with azimuthal symmetry. The results show a significantly larger fraction of the energy goes …

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Simultaneous Wound Border Segmentation And Tissue Classification Using A Conditional Generative Adversarial Network, Salih Sarp, Murat Kuzlu, Manisa Pipattanasomporn, Ozgur Guler Jan 2021

Simultaneous Wound Border Segmentation And Tissue Classification Using A Conditional Generative Adversarial Network, Salih Sarp, Murat Kuzlu, Manisa Pipattanasomporn, Ozgur Guler

Engineering Technology Faculty Publications

Generative adversarial network (GAN) applications on medical image synthesis have the potential to assist caregivers in deciding a proper chronic wound treatment plan by understanding the border segmentation and the wound tissue classification visually. This study proposes a hybrid wound border segmentation and tissue classification method utilising conditional GAN, which can mimic real data without expert knowledge. We trained the network on chronic wound datasets with different sizes. The performance of the GAN algorithm is evaluated through the mean squared error, Dice coefficient metrics and visual inspection of generated images. This study also analyses the optimum number of training images …

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The Enlightening Role Of Explainable Artificial Intelligence In Chronic Wound Classification, Salih Sarp, Murat Kuzlu, Emmanuel Wilson, Umit Cali, Ozgur Guler Jan 2021

The Enlightening Role Of Explainable Artificial Intelligence In Chronic Wound Classification, Salih Sarp, Murat Kuzlu, Emmanuel Wilson, Umit Cali, Ozgur Guler

Engineering Technology Faculty Publications

Artificial Intelligence (AI) has been among the most emerging research and industrial application fields, especially in the healthcare domain, but operated as a black-box model with a limited understanding of its inner working over the past decades. AI algorithms are, in large part, built on weights calculated as a result of large matrix multiplications. It is typically hard to interpret and debug the computationally intensive processes. Explainable Artificial Intelligence (XAI) aims to solve black-box and hard-to-debug approaches through the use of various techniques and tools. In this study, XAI techniques are applied to chronic wound classification. The proposed model classifies …

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Opportunistic Maintenance Strategy Of A Heave Compensation System For Expected Performance Degradation, Chao Zhang, Yujie Qian, Hongyan Dui, Shaoping Wang, Rentong Chen, Mileta M. Tomovic Jan 2021

Opportunistic Maintenance Strategy Of A Heave Compensation System For Expected Performance Degradation, Chao Zhang, Yujie Qian, Hongyan Dui, Shaoping Wang, Rentong Chen, Mileta M. Tomovic

Engineering Technology Faculty Publications

In the marine industry, heave compensation systems are applied to marine equipment to compensate for the adverse effects of waves and the hydraulic system is usually used as the power system of heave compensation systems. This article introduces importance theory to the opportunistic maintenance (OM) strategy to provide guidance for the maintenance of heave compensation systems. The working principle of a semi-active heave compensation system and the specific working states of its hydraulic components are also first explained. Opportunistic maintenance is applied to the semi-active heave compensation system. Moreover, the joint integrated importance measure (JIIM) between different components at different …

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Development Of An Undergraduate Welding Laboratory For Research And Education, Hamid Eisazadeh, Alok K. Verma Jan 2021

Development Of An Undergraduate Welding Laboratory For Research And Education, Hamid Eisazadeh, Alok K. Verma

Engineering Technology Faculty Publications

The shortage of welders in Hampton Roads area, where many shipyards are located, is becoming severe for shipbuilding in coming years. Many welding engineers graduated from universities located out of state, tend to go back to companies near their home, after receiving couple years of welding experience at Hampton Roads shipyards. Therefore, it is critical to train local welders. In order to address the welding workforce needs of Hampton Roads, the Department of Engineering Technology at Old Dominion University has recently launched an initiative for developing a laboratory for welding processes (LWP) for supporting educational and research activities in its …

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Pedagogical Methods And Advances For Synchronous/Asynchronous Instruction Of Laboratories In Engineering Technology Programs, Nestor Escobales, Alok Verma Jan 2021

Pedagogical Methods And Advances For Synchronous/Asynchronous Instruction Of Laboratories In Engineering Technology Programs, Nestor Escobales, Alok Verma

Engineering Technology Faculty Publications

Significant research has been done on the subject of distance learning (DL) instruction for many academic disciplines. However, when it comes to engineering technology (ET) programs, particularly, engineering laboratory work, limited studies are available. It is unquestionable that engineering laboratory work is essential for the successful preparation of individuals enrolled in ET programs. The focus of ET programs is on the correct use and application of engineering principles with a direct focus on practical application rather than on theory alone. The difficulties increase significantly when laboratories are offered in DL mode, particularly for ET programs. It is well known that …

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Engineering Technology Programs Outreach To K-12, Alok Verma Jan 2021

Engineering Technology Programs Outreach To K-12, Alok Verma

Engineering Technology Faculty Publications

The Engineering Technology (ET) degree emphasizes hands-on application and implementation. Graduates holding this degree play a valuable role in economically growing the US and keeping it internationally competitive. However, “engineering and engineering technology, are widely misunderstood… the public sector (employers, students, high-school counselors, politicians and the general public) needs to be educated as to the particular value of each,” according to Engineering.com [1]. The National Academy of Engineering states, “Unlike the much better-known field of engineering, engineering technology is unfamiliar to most Americans and goes unmentioned in most policy discussions about the US technical workforce. This is even though workers …

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Mentoring Prospective Engineering Students Through The After School Program "Girls In Engineering" Focused On Building An Underwater Remotely Operated Vehicle, Vukica M. Jovanović, Deborah Marshall, Jeff Warren Larson Jr., Abdul Rahman Badawi, Neil R. Stclair, Otilia Popescu, Murat Kuzlu, Petros J. Katsioloudis, Linda Vahala, Michael Anthony Crespo Jan 2021

Mentoring Prospective Engineering Students Through The After School Program "Girls In Engineering" Focused On Building An Underwater Remotely Operated Vehicle, Vukica M. Jovanović, Deborah Marshall, Jeff Warren Larson Jr., Abdul Rahman Badawi, Neil R. Stclair, Otilia Popescu, Murat Kuzlu, Petros J. Katsioloudis, Linda Vahala, Michael Anthony Crespo

Engineering Technology Faculty Publications

A number of studies by engineering education researchers have pointed out that all-female teams, rather than mixed teams, result in better forms of participation and interaction in engineering related after-school programs and clubs. In particular, for after-school programs or clubs that form in response to a STEM competition, all-female teams have better chances of developing. One such competition, which will be discussed in this paper, is a regional Marine Advanced Technology Education (MATE) competition in which students from Blind_Review High School have been participating for many years.For each year’s competition, an all-female team of students enrolled in the Career and …

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Biocybersecurity: A Converging Threat As An Auxiliary To War, Lucas Potter, Orlando Ayala, Xavier-Lewis Palmer Jan 2021

Biocybersecurity: A Converging Threat As An Auxiliary To War, Lucas Potter, Orlando Ayala, Xavier-Lewis Palmer

Engineering Technology Faculty Publications

Biodefense is the discipline of ensuring biosecurity with respect to select groups of organisms and limiting their spread. This field has increasingly been challenged by novel threats from nature that have been weaponized such as SARS, Anthrax, and similar pathogens, but has emerged victorious through collaboration of national and world health groups. However, it may come under additional stress in the 21st century as the field intersects with the cyberworld-- a world where governments have already been struggling to keep up with cyber attacks from small to state-level actors as cyberthreats have been relied on to level the playing field …

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Toward An Interactive, Patient-Specific, Vr-Based Obstetrics Simulator, Michel A. Audette, Marco Parente, Dulce Oliveira, Sreekanth Arikatla, Alfred Abuhamad, Rumit Singh Kakar, Mark Scerbo, Lucia Tabacu, John Conery, Christopher Macgowan, Renato Natal Jorge Jan 2021

Toward An Interactive, Patient-Specific, Vr-Based Obstetrics Simulator, Michel A. Audette, Marco Parente, Dulce Oliveira, Sreekanth Arikatla, Alfred Abuhamad, Rumit Singh Kakar, Mark Scerbo, Lucia Tabacu, John Conery, Christopher Macgowan, Renato Natal Jorge

Electrical & Computer Engineering Faculty Publications

This paper presents a nascent collaborative effort to achieve a Virtual Reality (VR)-based, real-time, haptics-driven patient-specific obstetrics simulator. The high-level architecture and preliminary results are presented here; the latter are based on offline birthing simulation developed by team in conjunction with open-source visualization tools. The cornerstones of this simulator will be high-fidelity generic offline birthing simulation, an anatomy-to-image nonrigid registration pipeline exploiting fetal MRI, the open-source interactive medical simulation toolkit IMSTK augmented by high-throughput deep learning-based soft tissue deformation, open-source musculoskeletal dynamics simulation platform SimTk for representing fetal motion. The initial emphasis will be on shoulder dystocia. The two main …

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Electroosmotic Flow Of Viscoelastic Fluid Through A Constriction Microchannel, Jianyu Ji, Shizhi Qian, Zhaohui Liu Jan 2021

Electroosmotic Flow Of Viscoelastic Fluid Through A Constriction Microchannel, Jianyu Ji, Shizhi Qian, Zhaohui Liu

Mechanical & Aerospace Engineering Faculty Publications

Electroosmotic flow (EOF) has been widely used in various biochemical microfluidic applications, many of which use viscoelastic non-Newtonian fluid. This study numerically investigates the EOF of viscoelastic fluid through a 10:1 constriction microfluidic channel connecting two reservoirs on either side. The flow is modelled by the Oldroyd-B (OB) model coupled with the Poisson–Boltzmann model. EOF of polyacrylamide (PAA) solution is studied as a function of the PAA concentration and the applied electric field. In contrast to steady EOF of Newtonian fluid, the EOF of PAA solution becomes unstable when the applied electric field (PAA concentration) exceeds a critical value for …

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A Case Study: Influence Of Circuit Impedance On The Performance Of Class-E² Resonant Power Converter For Capacitive Wireless Power Transfer, Yashwanth Bezawada, Yucheng Zhang Jan 2021

A Case Study: Influence Of Circuit Impedance On The Performance Of Class-E² Resonant Power Converter For Capacitive Wireless Power Transfer, Yashwanth Bezawada, Yucheng Zhang

Electrical & Computer Engineering Faculty Publications

The evolution of power electronics led to rapid development in wireless charging technology; as a result, a single active switch topology was introduced. The present market utilizes inductive wireless power transfer (IPT); because of the disadvantages of cost, size, and safety concerns, research on wireless power transfer was diverted towards capacitive wireless power transfer (CPT). This paper studies the optimal impedance tracking of the capacitive wireless power transfer system for maximum power transfer. Compared to prior methods developed for maximum power point tracking in power control, this paper proposes a new approach by means of finding impedance characteristics of the …

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Charge Transport, Conductivity And Seebeck Coefficient In Pristine And Tcnq Loaded Preferentially Grown Metal Organic Frameworks, Xin Chen, Kai Zhang, Zeinab Mohammed Hassan, Engelbert Redel, Helmut Baumgart Jan 2021

Charge Transport, Conductivity And Seebeck Coefficient In Pristine And Tcnq Loaded Preferentially Grown Metal Organic Frameworks, Xin Chen, Kai Zhang, Zeinab Mohammed Hassan, Engelbert Redel, Helmut Baumgart

Electrical & Computer Engineering Faculty Publications

This investigation on Metal-Organic Framework (MOF) HUKUST-1 films focuses on comparing the undoped pristine state and with the case of doping by TCNQ infiltration of the MOF pore structure. We have determined the temperature dependent charge transport and p-type conductivity for HKUST-1 films. Furthermore, the electrical conductivity and the current-voltage characteristics have been characterized in detail. Because the most common forms of MOFs, bulk MOF powders, do not lend themselves easily to electrical characterization investigations, here in this study the electrical measurements were performed on dense, compact surface-anchored metal-organic framework (SURMOF) films. These monolithic, well-defined, and (001) preferentially oriented MOF …

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Theoretical Analysis Of Experimental Data Of Sodium Diffusion In Oxidized Molybdenum Thin Films, Orlando Ayala, Benjamin Belfore, Tasnuva Ashrafee, John Akwari, Grace Rajan, Shankar Karki, Deewakar Poudel, Sylvain Marsillac Jan 2021

Theoretical Analysis Of Experimental Data Of Sodium Diffusion In Oxidized Molybdenum Thin Films, Orlando Ayala, Benjamin Belfore, Tasnuva Ashrafee, John Akwari, Grace Rajan, Shankar Karki, Deewakar Poudel, Sylvain Marsillac

Engineering Technology Faculty Publications

In this work, the diffusion process of sodium (Na) in molybdenum (Mo) thin films while it was deposited on soda lime glass (SLG) was studied. A small amount of oxygen was present in the chamber while the direct-current (DC) magnetron sputtering was used for the deposition. The substrate temperatures were varied to observe its effect. Such molybdenum films, with or without oxidations, are often used in thin film solar cells, either as back contact or as hole transport layers. Secondary ion mass spectrometry (SIMS) was used to quantify the concentration of the species. A grain diffusion mechanistic model incorporating the …

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The Influence Of Channel Deepening On Tides, River Discharge Effects, And Storm Surge, S. A. Talke, Ramin Familkhalili, D. A. Jay Jan 2021

The Influence Of Channel Deepening On Tides, River Discharge Effects, And Storm Surge, S. A. Talke, Ramin Familkhalili, D. A. Jay

Civil & Environmental Engineering Faculty Publications

We combine archival research, semi-analytical models, and numerical simulations to address the following question: how do changes to channel geometry alter tidal properties and flood dynamics in a hyposynchronous, strongly frictional estuary with a landward decay in tidal amplitudes? Records in the Saint Johns River Estuary since the 1890s show that tidal range has doubled in Jacksonville, Florida. Near the estuary inlet, tidal discharge approximately doubled but tidal amplitudes increased only ∼6%. Modeling shows that increased shipping channel depths from ∼5 to ∼13m drove the observed changes, with other factors like channel shortening and width reduction producing comparatively minor effects. …

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Characterizing Seagrass Effects On Hydrodynamics Of Waves And Currents Through Field Measurements And Computational Modelling, Ramin Familkhalili, Navid Tahvildari Jan 2021

Characterizing Seagrass Effects On Hydrodynamics Of Waves And Currents Through Field Measurements And Computational Modelling, Ramin Familkhalili, Navid Tahvildari

Civil & Environmental Engineering Faculty Publications

Low-lying coastal and estuarine areas are among the most populated regions globally, have high economic significance, and are increasingly threatened by climate change, sea level rise, nuisance flooding, and extreme storms. Nature-based coastal protections are sustainable and sea-level resilient alternatives compared to traditional solutions such as dikes and seawalls. Submerged aquatic vegetation (SAV) or seagrasses can provide coastal flood and erosion protection by attenuating storm wave and current energy and stabilizing seabed sediments. However, more research is needed to understand the interactions between flow, SAVs, and sediments. These dynamic interactions affect flow at different scales and seagrass productivity. In this …

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Morphology-Dependent Resonances In Two Concentric Spheres With Variable Refractive Index In The Outer Layer: Analytic Solutions, Umaporn Nuntaplook, John A. Adam Jan 2021

Morphology-Dependent Resonances In Two Concentric Spheres With Variable Refractive Index In The Outer Layer: Analytic Solutions, Umaporn Nuntaplook, John A. Adam

Mathematics & Statistics Faculty Publications

In many applications constant or piecewise constant refractive index profiles are used to study the scattering of plane electromagnetic waves by a spherical object. When the structured media has variable refractive indices, this is more of a challenge. In this paper, we investigate the morphology dependent resonances for the scattering of electromagnetic waves from two concentric spheres when the outer shell has a variable refractive index. The resonance analysis is applied to the general solutions of the radial Debye potential for both transverse magnetic and transverse electric modes. Finally, the analytic conditions to determine the resonance locations for this system …

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In Situ Recrystallization Of Co-Evaporated Cu(In,Ga)Se2 Thin Films By Copper Chloride Vapor Treatment Towards Solar Cell Applications, Deewakar Poudel, Benjamin Belfore, Tasnuva Ashrafee, Elizabeth Palmiotti, Shankar Karki, Grace Rajan, Thomas Lepetit, Angus Rockett, Sylvain Marsillac Jan 2021

In Situ Recrystallization Of Co-Evaporated Cu(In,Ga)Se2 Thin Films By Copper Chloride Vapor Treatment Towards Solar Cell Applications, Deewakar Poudel, Benjamin Belfore, Tasnuva Ashrafee, Elizabeth Palmiotti, Shankar Karki, Grace Rajan, Thomas Lepetit, Angus Rockett, Sylvain Marsillac

Applied Research Center Publications

Cu(In,Ga)Se2 (or CIGS) thin films and devices were fabricated using a modified three-stage process. Using high deposition rates and a low temperature during the process, a copper chloride vapor treatment was introduced in between the second and third stages to enhance the films properties. X-ray diffraction and scanning electron microscopy demonstrate that drastic changes occur after this recrystallization process, yielding films with much larger grains. Secondary ion mass spectrometry shows that the depth profile of many elements is not modified (such as Cu, In and Se) while others change dramatically (such as Ga and Na). Because of the competing …

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Effect Of Random Pinning On Nonlinear Dynamics And Dissipation Of A Vortex Driven By A Strong Microwave Current, W.P.M.R. Pathirana, Alex Gurevich Jan 2021

Effect Of Random Pinning On Nonlinear Dynamics And Dissipation Of A Vortex Driven By A Strong Microwave Current, W.P.M.R. Pathirana, Alex Gurevich

Physics Faculty Publications

We report numerical simulations of a trapped elastic vortex driven by a strong ac magnetic field H(t)=Hsinωt parallel to the surface of a superconducting film. The surface resistance and the power dissipated by an oscillating vortex perpendicular to the film surface were calculated as functions of H and ω for different spatial distributions, densities, and strengths of pinning centers, including bulk pinning, surface pinning, and cluster pinning. Our simulations were performed for both the Bardeen-Stephen viscous vortex drag and the Larkin-Ovchinnikov (LO) drag coefficient η(v) decreasing with the vortex velocity v. The local residual surface resistance Ri(H) …

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