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2021

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Model Computation With Second-Order Radiative Transfer Equation For Snow Medium Using Coupled Finite Element Method And Method Of Moment And Relaxed Hierarchical Equivalent Source Algorithm, Hamsalekha A. Kumaresan, H. T. Ewe, Gobi Vetharatnam, Li (Lijun) Jun Jiang Jan 2021

Model Computation With Second-Order Radiative Transfer Equation For Snow Medium Using Coupled Finite Element Method And Method Of Moment And Relaxed Hierarchical Equivalent Source Algorithm, Hamsalekha A. Kumaresan, H. T. Ewe, Gobi Vetharatnam, Li (Lijun) Jun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

Active microwave remote sensing is essential to monitor the conditions of the environment by analyzing the microwave returns from the earth terrain. Various Computational Electromagnetics (CEM) techniques are implemented to study the backscattering coefficient of numerous earth terrains such as vegetation and snow medium. In this paper, a theoretical model based on second order radiative transfer equation is investigated by incorporating two computational methods which are known as coupled Finite Element Method (FEM) and Method of Moment (MoM), and Relaxed Hierarchical Equivalent Source Algorithm (RHESA). These theoretical models consider three shapes of scatterers which can be used to represent the …

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Beyond Algorithms: Toward A Normative Theory Of Automated Regulation, Felix Mormann Jan 2021

Beyond Algorithms: Toward A Normative Theory Of Automated Regulation, Felix Mormann

Faculty Scholarship

The proliferation of artificial intelligence in our daily lives has spawned a burgeoning literature on the dawn of dehumanized, algorithmic governance. Remarkably, the scholarly discourse overwhelmingly fails to acknowledge that automated, non-human governance has long been a reality. For more than a century, policymakers have relied on regulations that automatically adjust to changing circumstances, without the need for human intervention. This article surveys the track record of self-adjusting governance mechanisms to propose a normative theory of automated regulation.

Effective policymaking frequently requires anticipation of future developments, from technology innovation to geopolitical change. Self-adjusting regulation offers an insurance policy against the …

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Effects Of Sentiments On The Morphing Of Falsehoods And Correction Messages On Social Media, Kelvin K. King, Bin Wang, Diego Escobari Jan 2021

Effects Of Sentiments On The Morphing Of Falsehoods And Correction Messages On Social Media, Kelvin K. King, Bin Wang, Diego Escobari

Information Systems Faculty Publications

The burgeoning literature on fake news reveals that the emotional context of the message is a major factor that drives its diffusion on social media. However, studies have largely missed a major aspect of the diffusion process, which is the morphing of the textual contents themselves during this process. Our study first visually illustrates through hazard functions that, while falsehoods morphs aggressively at the initial stages, correction messages morph more aggressively in the long run. In addition, we leverage on cosine distance and econometric modeling to empirically investigate how sentiment affects the morphing of fake news and their correction messages. …

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Decoupling Of Antennas With Adjacent Frequency Bands, Min Li, Lijun Jiang, Lawrence Kwan Yeung Jan 2021

Decoupling Of Antennas With Adjacent Frequency Bands, Min Li, Lijun Jiang, Lawrence Kwan Yeung

Electrical and Computer Engineering Faculty Research & Creative Works

A decoupling device called cascaded power dividing decoupling network (C-PDDN) is presented for two antennas operating in adjacent frequency bands. Design formulas are derived to determine parametrical variables for high isolation. A prototype of a testing array consisting of two base-station dipole antennas is realized on a Rogers PCB for demonstration purposes. Simulated and experimental results show that good impedance matching, and high isolation are achieved simultaneously after adopting the C-PDDN.

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Data-Driven Identification Of Governing Partial Differential Equations For The Transmission Line Systems, Yanming Zhang, Lijun Jiang Jan 2021

Data-Driven Identification Of Governing Partial Differential Equations For The Transmission Line Systems, Yanming Zhang, Lijun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

Discovering governing equations for transmission line is essential for the study on its properties, especially when the nonlinearity is introduced in a transmission line system. In this paper, we propose a novel data-driven approach for deriving the governing partial differential equations based on the spatial-temporal samples of current and voltage in the transmission line system. The proposed method is based on the ridge regression algorithm to determine the active spatial differential terms from the candidate library that includes nonlinear functions, in which the time and spatial derivatives are estimated by using polynomial interpolation. Three examples, including uniform and nonuniform transmission …

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The Easterbrook Theorem: An Application To Digital Markets, Joshua D. Wright, Murat C. Mungan Jan 2021

The Easterbrook Theorem: An Application To Digital Markets, Joshua D. Wright, Murat C. Mungan

Faculty Scholarship

The rise of large firms in the digital economy, including Amazon, Apple, Facebook, and Google, has rekindled the debate about monopolization law. There are proposals to make finding liability easier against alleged digital monopolists by relaxing substantive standards; to flip burdens of proof; and to overturn broad swaths of existing Supreme Court precedent, and even to condemn a law review article. Frank Easterbrook’s seminal 1984 article, The Limits of Antitrust, theorizes that Type I error costs are greater than Type II error costs in the antitrust context, a proposition that has been woven deeply into antitrust law by the Supreme …

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Microsphere Photolithography Patterned Nanohole Array On An Optical Fiber, Ibrahem Jasim, Jiayu Liu, Chen Zhu, Muhammad Roman, Jie Huang, Edward Kinzel, Mahmoud Almasri Jan 2021

Microsphere Photolithography Patterned Nanohole Array On An Optical Fiber, Ibrahem Jasim, Jiayu Liu, Chen Zhu, Muhammad Roman, Jie Huang, Edward Kinzel, Mahmoud Almasri

Electrical and Computer Engineering Faculty Research & Creative Works

Microsphere Photolithography (MPL) is a nanopatterning technique that utilizes a self-assembled monolayer of microspheres as an optical element to focus incident radiation inside a layer of photoresist. The microspheres produces a sub-diffraction limited photonic-jet on the opposite side of each microsphere from the illumination. When combined with pattern transfer techniques such as etching/lift-off, MPL provides a versatile, low-cost fabrication method for producing hexagonal close-packed metasurfaces. This article investigates the MPL process for creating refractive index (RI) sensors on the cleaved tips of optical fiber. The resonant wavelength of metal elements on the surface is dependent on the local dielectric environment …

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Optimal Bidding Strategy For Physical Market Participants With Virtual Bidding Capability In Day-Ahead Electricity Markets, Hossein Mehdipourpicha, Rui Bo Jan 2021

Optimal Bidding Strategy For Physical Market Participants With Virtual Bidding Capability In Day-Ahead Electricity Markets, Hossein Mehdipourpicha, Rui Bo

Electrical and Computer Engineering Faculty Research & Creative Works

Virtual bidding provides a mechanism for financial players to participate in wholesale day-ahead (DA) electricity markets. The price difference between DA and real-time (RT) markets creates financial arbitrage opportunities for financial players. Physical market participants (MP), referred to as participants with physical assets, can also take advantage of virtual bidding but in a different way, which is to further amplify the value of their physical assets. Therefore, this work proposes a model for such physical MPs to maximize the profits. This model employs a bi-level optimization approach, where the upper-level subproblem maximizes the total profit from both physical generations and …

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A Convolutional Neural Network Model Based On Multiscale Structural Similarity For The Prediction Of Flow Fields, Yifu An, Xiaosong Du, Joaquim R.R.A. Martins Jan 2021

A Convolutional Neural Network Model Based On Multiscale Structural Similarity For The Prediction Of Flow Fields, Yifu An, Xiaosong Du, Joaquim R.R.A. Martins

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We have seen the emerging applications of deep neural networks for flow field predictions in the past few years. Most of the efforts rely on the increased complexity of the model itself or take advantage of novel network architectures, such as convolutional neural networks (CNN). However, reaching low prediction error cannot guarantee the quality of the predicted flow fields in terms of the perceived visual quality. This work introduces the multi-scale structural similarity (MS-SSIM) index method for flow field prediction. First, we train CNN models using the commonly used root mean squared error (RMSE) loss function as the reference. Then …

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Simulations Of Single- And Two-Tone Tm-Doped Optical Fiber Laser Amplifiers, Tathagata Goswami, J. Grosek, Jay Gopalakrishnan Jan 2021

Simulations Of Single- And Two-Tone Tm-Doped Optical Fiber Laser Amplifiers, Tathagata Goswami, J. Grosek, Jay Gopalakrishnan

Mathematics and Statistics Faculty Publications and Presentations

This work uses numerical simulations of a thulium-doped optical fiber amplifier to predict various performance characteristics such as peak temperatures, expected output powers and efficiencies, presence of amplified spontaneous emission (ASE), and transverse mode instability (TMI) onset power thresholds. Single- and two-tone configurations are studied. In the latter case, the two laser sources are separated in frequency by the amount that corresponds to the peak Raman gain, and a few seed ratios at various total seed powers are examined. The goal is to provide the field with pertinent information on what is feasible for this type of amplifier.

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Data-Driven Wildfire Risk Prediction In Northern California, Ashima Malik, Megha Rajam Rao, Nandini Puppala, Prathusha Koouri, Venkata Anil Kumar Thota, Qiao Liu, Sen Chiao, Jerry Gao Jan 2021

Data-Driven Wildfire Risk Prediction In Northern California, Ashima Malik, Megha Rajam Rao, Nandini Puppala, Prathusha Koouri, Venkata Anil Kumar Thota, Qiao Liu, Sen Chiao, Jerry Gao

Faculty Research, Scholarly, and Creative Activity

Over the years, rampant wildfires have plagued the state of California, creating economic and environmental loss. In 2018, wildfires cost nearly 800 million dollars in economic loss and claimed more than 100 lives in California. Over 1.6 million acres of land has burned and caused large sums of environmental damage. Although, recently, researchers have introduced machine learning models and algorithms in predicting the wildfire risks, these results focused on special perspectives and were restricted to a limited number of data parameters. In this paper, we have proposed two data-driven machine learning approaches based on random forest models to predict the …

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Effects Of Figural And Numerical Presentation Formats On Growing Pattern Performance, Marta K. Mielicki, Charlies J. Fitzsimmons, Lauren H. Woodbury, Hannah Marshal, Dake Zhang, Ferdinand D. Rivera, Clarissa A. Thompson Jan 2021

Effects Of Figural And Numerical Presentation Formats On Growing Pattern Performance, Marta K. Mielicki, Charlies J. Fitzsimmons, Lauren H. Woodbury, Hannah Marshal, Dake Zhang, Ferdinand D. Rivera, Clarissa A. Thompson

Faculty Research, Scholarly, and Creative Activity

Prior work exploring preschool-aged children’s reasoning with repeating patterns has shown that patterning ability is an important predictor of math achievement; however, there is limited research exploring older children’s growing pattern task performance. The current study tested whether presentation format impacts performance on growing pattern problems, and whether the effects of presentation format extend to transfer word problems for which no patterns are provided. Sixth grade students were randomly assigned to complete several growing pattern tasks in one of three presentation formats (figures, sequences of values, or tables of values), and later completed transfer story problems with no figures, sequences, …

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On The Edge Irregular Reflexive Labeling Of Corona Product Of Graphs With Path, Kooi Kuan Yoong, Roslan Hasni, Muhammad Irfan, Ibrahim Taraweh, Ali Ahmad, Sin Min Lee Jan 2021

On The Edge Irregular Reflexive Labeling Of Corona Product Of Graphs With Path, Kooi Kuan Yoong, Roslan Hasni, Muhammad Irfan, Ibrahim Taraweh, Ali Ahmad, Sin Min Lee

Faculty Research, Scholarly, and Creative Activity

We define a total k-labeling (Formula presented.) of a graph G as a combination of an edge labeling (Formula presented.) and a vertex labeling (Formula presented.) such that (Formula presented.) if (Formula presented.) and (Formula presented.) if (Formula presented.) where (Formula presented.) The total k-labeling (Formula presented.) is called an edge irregular reflexive k-labeling of G if every two different edges has distinct edge weights, where the edge weight is defined as the summation of the edge label itself and its two vertex labels. Thus, the smallest value of k for which the graph G has the edge irregular reflexive …

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Degrees Of Support: State Spending On Higher Education And Public Postsecondary Degrees Across State Legislatures, 2005 And 2014, Kristen Shorette, Megan Thiele, Catherine Bolzendahl Jan 2021

Degrees Of Support: State Spending On Higher Education And Public Postsecondary Degrees Across State Legislatures, 2005 And 2014, Kristen Shorette, Megan Thiele, Catherine Bolzendahl

Faculty Research, Scholarly, and Creative Activity

U.S. state spending on higher education represents a sizable, but highly variable, portion of budget expenditures. Preliminary research supports a positive relationship between the percentage of state legislators who hold public degrees and state funding for higher education. In this study, the authors test whether this finding is consistent over time by using panel modeling to analyze the educational compositions of state legislatures in 2005 and 2014. Generalized least squares regression models with robust standard errors clustered by state- and year-specific intercepts indicate a significantly positive relationship between the proportion of publicly educated state legislators and state spending on higher …

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Review On Resistive Switching Mechanisms Of Bio-Organic Thin Film For Non-Volatile Memory Application, Kuan Yew Cheong, Ilias Ait Tayeb, Feng Zhao, Jafri Malin Abdullah Jan 2021

Review On Resistive Switching Mechanisms Of Bio-Organic Thin Film For Non-Volatile Memory Application, Kuan Yew Cheong, Ilias Ait Tayeb, Feng Zhao, Jafri Malin Abdullah

Electrical and Computer Engineering Faculty Research & Creative Works

Bio-organic, as one of the sustainable and bioresorbable materials, has been used as an active thin film in producing resistive switching random access memory (RRAM) due to its specialized properties. This type of nonvolatile memory consists of a simple unit structure with the processed and solidified bio-organic-based thin film sandwiched between two electrodes. Its memory characteristics are significantly affected by the resistive-switching mechanism. However, to date, the reported mechanisms are very diverse and scattered, and to our best knowledge, there is no literature that reviewed comprehensively the mechanisms of resistive switching in bio-organic-based thin films. Therefore, the objective of this …

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Image Analysis Of Colloidal Systems For Pair And Triplet Correlations., Brianna Price Jan 2021

Image Analysis Of Colloidal Systems For Pair And Triplet Correlations., Brianna Price

Electronic Theses and Dissertations

Interactions among colloidal particles drive stability of suspensions or the assembly of particles into larger superstructures such as agglomerates or crystals. Typically, colloidal interactions are modeled using pairwise interaction potential energies which consider the interactions between pairs of particles. However, additional particles can modulate pair potentials, leading models to predict incorrect behavior. To analyze the effects of three-body interactions on the structuring of colloidal systems, pair and triplet correlation functions are calculated from published experimental data. These correlation functions are then translated into empirical pair and triplet potentials of mean force, which are then used to model systems more accurately …

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2020 Kentucky Transportation Cabinet Maintenance Customer Survey, Bryan Gibson, Katherine Connair, Chris Van Dyke, Clark Graves, Doug Kreis Jan 2021

2020 Kentucky Transportation Cabinet Maintenance Customer Survey, Bryan Gibson, Katherine Connair, Chris Van Dyke, Clark Graves, Doug Kreis

Kentucky Transportation Center Research Report

The Kentucky Transportation Cabinet (KYTC) periodically surveys drivers to understand their perceptions of the agency’s maintenance activities. In 2020, Quadratics in conjunction with the Kentucky Transportation Center surveyed 2,400 licensed drivers throughout the state to gauge their perceptions of highway maintenance, identify areas of strength and weakness, and discern how drivers obtain information on traffic and weather conditions. Survey participants answered questions about five areas of highway maintenance — roadside features, pavement surfaces, shoulders, drainage, and signs/markings. Drivers reported being most satisfied with the maintenance of signs, guardrail, and striping. Pavement surfaces, potholes, and overall appearance garnered the lowest ratings. …

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Mucins, Gut Microbiota, And Postbiotics Role In Colorectal Cancer, Ramesh Pothuraju, Sanjib Chaudhary, Satyanarayana Rachagani, Sukhwinder Kaur, Hemant K Roy, Michael Bouvet, Surinder K Batra Jan 2021

Mucins, Gut Microbiota, And Postbiotics Role In Colorectal Cancer, Ramesh Pothuraju, Sanjib Chaudhary, Satyanarayana Rachagani, Sukhwinder Kaur, Hemant K Roy, Michael Bouvet, Surinder K Batra

Faculty, Staff and Students Publications

An imbalance in the crosstalk between the host and gut microbiota affects the intestinal barrier function, which results in inflammatory diseases and colorectal cancer. The colon epithelium protects itself from a harsh environment and various pathogenic organisms by forming a double mucus layer, primarily comprising mucins. Recent studies are focusing on how dietary patterns alter the gut microbiota composition, which in turn regulates mucin expression and maintains the intestinal layers. In addition, modulation of gut microbiota by microbiotic therapy (involving fecal microbiota transplantation) has emerged as a significant factor in the pathologies associated with dysbiosis. Therefore, proper communication between host …

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Assessment Of Cable Length Limit For Effective Protection By Z-Source Circuit Breakers In Dc Power Networks, Ruiyun Fu, Sagar Bhatta, Joseph M. Keller, Yucheng Zhang Jan 2021

Assessment Of Cable Length Limit For Effective Protection By Z-Source Circuit Breakers In Dc Power Networks, Ruiyun Fu, Sagar Bhatta, Joseph M. Keller, Yucheng Zhang

Electrical & Computer Engineering Faculty Publications

This paper introduces groundbreaking research on how to assess the Cable Length Limit (CLL) to ensure effective protection by Z-source Circuit Breakers (ZCBs) in DC power networks. It has been revealed that the line parameters of power cables have a significant impact on the cutoff performance of ZCBs. The question of assessing the CLL has been raised as an unsolved problem. In this paper, a method of CLL assessment is proposed based on physical models and simulation tests. To verify the proposed method, two studies were performed to assess the Cable Length Limits depending on fault levels and power delivery …

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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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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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Rapid Quantification Of Biofouling With An Inexpensive, Underwater Camera And Image Analysis, Matthew R. First, Scott C. Riley, Kazi Aminul Islam, Victoria Hill, Jiang Li, Richard C. Zimmerman, Lisa A. Drake Jan 2021

Rapid Quantification Of Biofouling With An Inexpensive, Underwater Camera And Image Analysis, Matthew R. First, Scott C. Riley, Kazi Aminul Islam, Victoria Hill, Jiang Li, Richard C. Zimmerman, Lisa A. Drake

Electrical & Computer Engineering Faculty Publications

To reduce the transport of potentially invasive species on ships' submerged surfaces, rapid-and accurate-estimates of biofouling are needed so shipowners and regulators can effectively assess and manage biofouling. This pilot study developed a model approach for that task. First, photographic images were collected in situ with a submersible, inexpensive pocket camera. These images were used to develop image processing algorithms and train machine learning models to classify images containing natural assemblages of fouling organisms. All of the algorithms and models were implemented in a widely available software package (MATLAB©). Initially, an unsupervised clustering model was used, and three …

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Hole Cleaning And Cuttings Transportation Modelling And Optimization, Foued Badrouchi Jan 2021

Hole Cleaning And Cuttings Transportation Modelling And Optimization, Foued Badrouchi

Theses and Dissertations

Efficient hole cleaning in drilling operation is essential to ensure optimum rate of penetration. This complex problem involves simultaneous analysis of multiple parameters, including cuttings characteristics, fluid rheology and the geometry of the annulus space. For instance, accurate calculations of the equivalent circulation density (ECD) requires the effect of the mud density increase due to the cuttings’ concentration to be considered, which itself is a function of the settling velocity and the rate of penetration (ROP). Analytical models, lab experiments and numerical simulations have been used to determine the optimum flow rate for efficient hole cleaning. Most of these models …

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Reflection And Transmission Of Electromagnetic Pulses At A Planar Dielectric Interface: Theory And Quantum Lattice Simulations, Abhay K. Ram, George Vahala, Linda Vahala, Min Soe Jan 2021

Reflection And Transmission Of Electromagnetic Pulses At A Planar Dielectric Interface: Theory And Quantum Lattice Simulations, Abhay K. Ram, George Vahala, Linda Vahala, Min Soe

Electrical & Computer Engineering Faculty Publications

There is considerable interest in the application of quantum information science to advance computations in plasma physics. A particular point of curiosity is whether it is possible to take advantage of quantum computers to speed up numerical simulations relative to conventional computers. Many of the topics in fusion plasma physics are classical in nature. In order to implement them on quantum computers, it will require couching a classical problem in the language of quantum mechanics. Electromagnetic waves are routinely used in fusion experiments to heat a plasma or to generate currents in the plasma. The propagation of electromagnetic waves is …

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Formal Power Series Approach To Nonlinear Systems With Static Output Feedback, G.S. Venkatesh, W. Steven Gray Jan 2021

Formal Power Series Approach To Nonlinear Systems With Static Output Feedback, G.S. Venkatesh, W. Steven Gray

Electrical & Computer Engineering Faculty Publications

The goal of this paper is to compute the generating series of a closed-loop system when the plant is described in terms of a Chen-Fliess series and static output feedback is applied. The first step is to reconsider the so called Wiener-Fliess connection consisting of a Chen-Fliess series followed by a memoryless function. Of particular importance will be the contractive nature of this map, which is needed to show that the closed-loop system has a Chen-Fliess series representation. To explicitly compute the generating series, two Hopf algebras are needed, the existing output feedback Hopf algebra used to describe dynamic output …

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Continuity Of Chen-Fliess Series For Applications In System Identification And Machine Learning, Rafael Dahmen, W. Steven Gray, Alexander Schmeding Jan 2021

Continuity Of Chen-Fliess Series For Applications In System Identification And Machine Learning, Rafael Dahmen, W. Steven Gray, Alexander Schmeding

Electrical & Computer Engineering Faculty Publications

Model continuity plays an important role in applications like system identification, adaptive control, and machine learning. This paper provides sufficient conditions under which input-output systems represented by locally convergent Chen-Fliess series are jointly continuous with respect to their generating series and as operators mapping a ball in an Lp-space to a ball in an Lq-space, where p and q are conjugate exponents. The starting point is to introduce a class of topological vector spaces known as Silva spaces to frame the problem and then to employ the concept of a direct limit to describe convergence. The proof of the main …

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Assessment Of Cu(In, Ga)Se₂ Solar Cells Degradation Due To Water Ingress Effect On The Cds Buffer Layer, Deewakar Poudel, Benjamin Belfore, Shankar Karki, Grace Rajan, Sina Soltanmohammad, Angus Rockett, Sylvain Marsillac Jan 2021

Assessment Of Cu(In, Ga)Se₂ Solar Cells Degradation Due To Water Ingress Effect On The Cds Buffer Layer, Deewakar Poudel, Benjamin Belfore, Shankar Karki, Grace Rajan, Sina Soltanmohammad, Angus Rockett, Sylvain Marsillac

Electrical & Computer Engineering Faculty Publications

The effect of water ingress on the surface of the buffer layer of a Cu(In, Ga)Se2 (CIGS) solar cell was studied. Such degradation can occur either during the fabrication process, if it involves a chemical bath as is often the case for CdS, or while the modules are in the field and encapsulants degrade. To simulate the impact of this moisture ingress, devices with a structure sodalime glass/Mo/CIGS/CdS were immersed in deionized water. The thin films were then analyzed both pre and post water soaking. Dynamic secondary ion mass spectroscopy (SIMS) was performed on completed devices to analyze impurity diffusion …

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High Voltage Design And Evaluation Of Wien Filters For The Cebaf 200 Kev Injector Upgrade, Gabriel Palacios-Serrano, Helmut Baumgart, C. Hernández-García, P. Adderley, J. Benesch, D. Bullard, J. Grames, A. Hofler, D. Machie, M. Poelker, M. Stutzman, R. Suleiman Jan 2021

High Voltage Design And Evaluation Of Wien Filters For The Cebaf 200 Kev Injector Upgrade, Gabriel Palacios-Serrano, Helmut Baumgart, C. Hernández-García, P. Adderley, J. Benesch, D. Bullard, J. Grames, A. Hofler, D. Machie, M. Poelker, M. Stutzman, R. Suleiman

Electrical & Computer Engineering Faculty Publications

High-energy nuclear physics experiments at the Jefferson Lab Continuous Electron Beam Accelerator Facility (CEBAF) require highly spin-polarization electron beams, produced from strained super-lattice GaAs photocathodes, activated to negative electron affinity in a photogun operating at 130 kV dc. A pair of Wien filter spin rotators in the injector defines the orientation of the electron beam polarization at the end station target. An upgrade of the CEBAF injector to better support the upcoming MOLLER experiment requires increasing the electron beam energy to 200 keV, to reduce unwanted helicity correlated intensity and position systematics and provide precise control of the polarization orientation. …

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Simulation Studies On The Interactions Of Electron Beam With Wastewater, X. Li, S. Wang, Helmut Baumgart, G. Ciovati, F. Hannon Jan 2021

Simulation Studies On The Interactions Of Electron Beam With Wastewater, X. Li, S. Wang, Helmut Baumgart, G. Ciovati, F. Hannon

Electrical & Computer Engineering Faculty Publications

The manufactured chemical pollutants, like 1,4 dioxane and PFAS (per- and polyfluroralkyl substances), found in the underground water and/or drinking water are challenging to be removed or biodegraded. Energetic electrons are capable of mediating and removing them. This paper utilizes FLUKA code to evaluate the beam-wastewater interaction effects with different energy, space and divergence distributions of the electron beam. With 8 MeV average energy, the electron beam exits from a 0.0127 cm thick titanium window, travels through a 4.3 cm distance air and a second 0.0127 cm thick stainless water container window with 2.43 cm radius, and finally is injected …

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Identification Of New Per- And Polyfluoroalkyl Substances (Pfas) In Aqueous Film-Forming Foam (Afff), Venus Rivera Larson Jan 2021

Identification Of New Per- And Polyfluoroalkyl Substances (Pfas) In Aqueous Film-Forming Foam (Afff), Venus Rivera Larson

Theses and Dissertations

The extraordinary number of unknown per- and polyfluoroalkyl substances (PFAS) necessitates identifying the substances as a first step to understanding them and their risks. From an environmental engineering perspective (preventing, controlling, and remediating), PFAS remediation and control measures are only as effective as the tools used to detect them. Focusing on aqueous film-forming foam (AFFF), several researchers have elucidated the structures of unknown PFAS, with each study accomplishing PFAS identification differently. A range of software and practices were used to improve mass spectrometry (MS) results or elucidate chemical structures. Different identification approaches were compared in the current research, including suspected …

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