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"A Comparison Of Variable Selection Methods Using Bootstrap Samples From Environmental Metal Mixture Data", Paul-Yvann Djamen 4785403, Paul-Yvann Djamen 2020 University Of New Mexico

"A Comparison Of Variable Selection Methods Using Bootstrap Samples From Environmental Metal Mixture Data", Paul-Yvann Djamen 4785403, Paul-Yvann Djamen

Mathematics & Statistics ETDs

In this thesis, I studied a newly developed variable selection method SODA, and three customarily used variable selection methods: LASSO, Elastic net, and Random forest for environmental mixture data. The motivating datasets have neuro-developmental status as responses and metal measurements and demographic variables as covariates. The challenges for variable selections include (1) many measured metal concentrations are highly correlated, (2) there are many possible ways of modeling interactions among the metals, (3) the relationships between the outcomes and explanatory variables are possibly nonlinear, (4) the signal to noise ratio in the real data may be low. To compare these methods ...


Effects On Strength And Corrosive Characteristics Of Hardened Cement Paste Using Rice Husk And Sugarcane Bagasse, Travis D. Garrett 2020 Louisiana Tech University

Effects On Strength And Corrosive Characteristics Of Hardened Cement Paste Using Rice Husk And Sugarcane Bagasse, Travis D. Garrett

Master's Theses

Cement is one of the most used building materials in the world. The production of ordinary Portland cement contributes to the release of harmful greenhouse gasses. In an effort to reduce these emissions, different materials are being evaluated for their use as partial replacements for ordinary Portland cement. Rice husk and sugarcane bagasse are agricultural waste products and large amounts of these are currently landfilled, making them inexpensive and available. When combusted at high temperatures they form rice husk ash and sugarcane bagasse ash that have pozzolanic characteristics. The high silicon dioxide in these products makes them good options to ...


Characterization Of Oxone Mediated Tempo-Oxidized Nano Cellulose Mixed-Matrix Membranes During Ultrafiltration And Hemodialysis, Kristyn Robling 2020 University of Arkansas, Fayetteville

Characterization Of Oxone Mediated Tempo-Oxidized Nano Cellulose Mixed-Matrix Membranes During Ultrafiltration And Hemodialysis, Kristyn Robling

Biomedical Engineering Undergraduate Honors Theses

The ninth leading cause of death in the United States is kidney disease, and hemodialysis is the process most commonly prescribed for treatment. It utilizes a selectively permeable membrane filter to remove toxins such as urea from the blood and retain necessary protein levels. However, traditional filters, such as cellulose triacetate, used during dialysis can be inefficient in terms of separation performance and reduction of fouling. Recent exploration of nanoparticles has resulted in the creation of Oxone Mediated TEMPO-Oxidized Nano Cellulose which has properties that are believed to increase hydrophilicity, increase tensile capacity, decrease membrane resistance and lower fouling, making ...


Countermeasures For Pedestrian-Involved Accidents On Interstate-Highways, Anna C. Hunter 2020 University of Arkansas, Fayetteville

Countermeasures For Pedestrian-Involved Accidents On Interstate-Highways, Anna C. Hunter

Civil Engineering Undergraduate Honors Theses

Pedestrian access to the Interstate is prohibited, but many pedestrian-involved accidents still occur on the Interstate in the United States. This project is a case study of West Memphis, Arkansas, which has the second highest occurrence of pedestrian-involved accidents on the Interstate in Arkansas. The study site location includes a segment of Interstate I-40 which is at- grade. The surrounding area contains several different land-uses, which is believed to be the primary generator of these accidents. The goal of this project is to determine the primary causes of these accidents and determine potential countermeasures to reduce the crash rate for ...


Nurbs-Based Microstructure Design For Organic Photovoltaics, Ramin Noruzi, Sambit Ghadai, Onur Rauf Bingol, Adarsh Krishnamurthy, Baskar Ganapathysubramanian 2020 Iowa State University

Nurbs-Based Microstructure Design For Organic Photovoltaics, Ramin Noruzi, Sambit Ghadai, Onur Rauf Bingol, Adarsh Krishnamurthy, Baskar Ganapathysubramanian

Mechanical Engineering Publications

The microstructure – spatial distribution of electron donor and acceptor domains – plays an important role in determining the photo current in thin film organic solar cells (OSCs). Optimizing the microstructure can lead to higher photo current generation, and is an active area of experimental research. There has been recent progress in framing OSC microstructure design as a computational design problem. However, most current approaches to microstructure optimization are based on volumetric distribution of material, which makes the design space very large. In contrast, we frame the microstructure design optimization problem in terms of designing the interface between the donor and acceptor ...


Improving An Experimental Test Bed With Time-Varying Parameters For Developing High-Rate Structural Health Monitoring Methods, D. T. Foley, B. S. Joyce, J. Hong, Simon Laflamme, J. Dodson 2020 University of Florida

Improving An Experimental Test Bed With Time-Varying Parameters For Developing High-Rate Structural Health Monitoring Methods, D. T. Foley, B. S. Joyce, J. Hong, Simon Laflamme, J. Dodson

Civil, Construction and Environmental Engineering Publications

With the development of complex structures with high-rate dynamics, such as space structures, weapons systems, or hypersonic vehicles, comes a need for real-time structural health monitoring (SHM) methods. Researchers are developing algorithms for high-rate SHM methods, however, limited data exists on which to test these algorithms. An experimental test bed to simulate high-rate systems with rapid parameter changes was previously presented by the authors. This paper expands on the previous work. The initial configuration consisted of a cantilevered steel beam with a cart-roller system on a linear actuator to create an adjustable boundary condition along the beam, as well as ...


Economic Efficiency & Carbon Emissions In Mes With Flexible Buildings, Zach Lawrence Hurwitz 2020 University of Vermont

Economic Efficiency & Carbon Emissions In Mes With Flexible Buildings, Zach Lawrence Hurwitz

Graduate College Dissertations and Theses

Multi-energy systems offer an opportunity to leverage energy conversion processes and temporary energy storage mechanisms to reduce costs and emissions during operation of campuses, cities, and buildings. With increasing options for flexibility in demand-side resources it is possible to meet demand without sacrificing comfort and convenience of MES occupants.

This Thesis develops a multi-period, linear optimization model of an MES with flexible buildings that captures nonlinearities in the efficiency of energy conversion processes. The flexible buildings are parametrized, in part, based on historical data from a college campus in Vermont, USA. The idea of the MES model is to investigate ...


Impact Of Chain Architecture On The Thickness Dependence Of Physical Aging Rate Of Thin Polystyrene Films, Gregory Brown, Elizabeth Lewis, Bryan D. Vogt 2020 University of Akron

Impact Of Chain Architecture On The Thickness Dependence Of Physical Aging Rate Of Thin Polystyrene Films, Gregory Brown, Elizabeth Lewis, Bryan D. Vogt

Williams Honors College, Honors Research Projects

The dynamics of polymer thin films have been demonstrated to be significantly altered from the bulk, but the origins of such differences are not well defined. In this work, we seek to understand the differences in the structural dynamics (or physical aging) of polystyrene (PS) through branching and other well defined architectures (comb and centipede). The aging dynamics of ultrathin films (< 30 nm) differ from relatively thick films (100-150nm) with linear PS thin films aging more rapidly than the relatively “bulk-like” thick films. Ellipsometric measurements are used to characterize the physical aging rate of the films. The change in film thickness and refractive index as the films are held below the glass transition temperature (Tg) provides a simple measure of the physical aging. In this study, four different architectures (linear, comb, 4 arm star, and centipede) will be investigated. For each PS architecture, the aging rate will be determined for film thickness ranging ...


Prevention Of Harmful Algal Blooms By The Mitigation Of Phosphorus Nutrient Loading Via Filtration By Steel Wool And Activated Carbon, Samantha Zidd, Sara Kidd, Ronald Simpson 2020 The University of Akron

Prevention Of Harmful Algal Blooms By The Mitigation Of Phosphorus Nutrient Loading Via Filtration By Steel Wool And Activated Carbon, Samantha Zidd, Sara Kidd, Ronald Simpson

Williams Honors College, Honors Research Projects

Harmful Algal Blooms (HABs) are a devastating ecological and economic consequence of the abundance of nutrient-rich agricultural runoff entering aquatic ecosystems (Baker et al. 2014). Bioavailable phosphorus from synthetic fertilizers is one of the major nutrients contributing to this global issue. Preliminary studies indicate that dissolved phosphorus can be removed from an aqueous environment when passed through a composite mixture of granular steel wool particles and activated carbon (Erickson, Gulliver, and Weiss (2007). Further research was conducted using higher quality concentration measurements to determine what grades of steel wool (0000, 000, 00) and types of activated carbon (GAC, PAC, EAC ...


Electrathon Vehicle: Steering, Lathan Halaapiapi 2020 Central Washington University

Electrathon Vehicle: Steering, Lathan Halaapiapi

All Undergraduate Projects

The Electrathon Vehicle project is an ongoing project that dates back to 2012. The Electrathon Vehicle began as a frame and three wheels when given to the EV club. In past projects the vehicle has had frame and suspension work. The current design is only partially assembled and does not allow for any steering in the vehicle. A steering system needed to be developed in order for the vehicle to be controlled while a person is sitting in the seat. A steering system was designed that could withstand the force of maneuvering the vehicle in excess of 30 mph. This ...


Prosthetic Hand: Structure, Riley Smith, Riley Smith 2020 Central Washington University

Prosthetic Hand: Structure, Riley Smith, Riley Smith

All Undergraduate Projects

The objective of this project was to design the structure of a prosthetic hand that has articulating fingers and thumb in order to grip various objects. A design was developed that can add to the available options of prosthetics on the market.

In order to create a base hand for the project, the hand was modeled off of rough human hand dimensions. Analyses determined the feasible size of components. Once a base size was found the movement system in both grip and return form were developed and refined. With the parts being modeled in Solidworks and 3D printed, iterations of ...


Electrathon Vehicle: Front Suspension, Christopher Clark 2020 Central Washington University

Electrathon Vehicle: Front Suspension, Christopher Clark

All Undergraduate Projects

Central Washington University does not currently have a competition field-able Electrathon America electric vehicle with adequate front suspension. The aim of this project was to provide the vehicle with handling that supports sound ground contact throughout the competition environment. Handling that supports sound ground contact is important for vehicles so they can go around corners without a loss of traction or flipping over. The solution to this engineering problem was designed and tested through various requirements. The requirements at hand were that the suspension components weigh less than 50 pounds, that there be no more than 3 inches of suspension ...


Negative Sequence Voltage Compensating For Unbalanced Standalone Brushless Doubly-Fed Induction Generator, Wei Xu, Omer Mohammed Elbabo Mohammed, Yi Liu, Md Rabiul Islam 2020 Huazhong University of Science and Technology

Negative Sequence Voltage Compensating For Unbalanced Standalone Brushless Doubly-Fed Induction Generator, Wei Xu, Omer Mohammed Elbabo Mohammed, Yi Liu, Md Rabiul Islam

Faculty of Engineering and Information Sciences - Papers: Part B

During the unbalance operation of a standalone brushless doubly-fed induction generator (BDFIG), the negative sequence component causes significant unbalanced effect on the voltage and current of the power winding (PW). In this paper, anew control strategy is proposed to minimize the voltage unbalance effect of a standalone BDFIG under unbalanced loads. The proposed control strategy consists of two parts. The first part represents the conventional direct voltage control (DVC) strategy to control the frequency and magnitude of the positivesequence PW voltage. The second part is the proposed strategy to minimize the negative sequence component in the output voltage of PW ...


Multiphase Identification In Ni-Pbte Contacts By Ebsd And Aberration-Corrected Stem, Xavier Reales Ferreres, Gilberto Casillas, Sima Aminorroaya-Yamini, Azdiar Adil Gazder 2020 University of Wollongong

Multiphase Identification In Ni-Pbte Contacts By Ebsd And Aberration-Corrected Stem, Xavier Reales Ferreres, Gilberto Casillas, Sima Aminorroaya-Yamini, Azdiar Adil Gazder

Australian Institute for Innovative Materials - Papers

EBSD in combination with aberration-corrected STEM is used to study the interfacial layer forming at Ni electrode - PbTe thermoelectric material interfaces. Contrary to previous studies, both orthorhombic and monoclinic phases are identified within the interfacial layer. EBSD and STEM data at interphase boundaries demonstrate an approximately smooth transition from orthorhombic to monoclinic phase with almost no crystal defects due to the small differences in lattice parameters and the prevalence of one of two previously unknown orientation relationships between the phases. Moreover, the presence of special boundaries resulting in orientation domains within both phases throughout the interfacial nickel telluride layer needs ...


The Biased Media And Their Utilization Of Propaganda: The True Obstructionists Of World Events And Our Minds, David B. Ross, Gina Peyton, Melissa Tara Sasso, Rande Matteson, Cortney Matteson 2019 Nova Southeastern University

The Biased Media And Their Utilization Of Propaganda: The True Obstructionists Of World Events And Our Minds, David B. Ross, Gina Peyton, Melissa Tara Sasso, Rande Matteson, Cortney Matteson

Dr. Melissa Tara Sasso

Propaganda is a widely controversial issue, especially when it collides with the media and politicians. This complex system creates tension between those who have a personal agenda to disseminate false statements to advance their plan to manipulate the minds of the public. Based upon 24/7 cable news and social media, there seems to be a miscommunication and disconnect from the truth regarding how the media reports world events, politics, environment, and how politicians were elected to help their constituents, not their own personal agendas. This chapter will address the concern for a better system of reporting the facts and ...


A Laboratory Investigation Of Cement Based Materials With Cellulose Nanofibers, Parivash Takasi 2019 University of Maine

A Laboratory Investigation Of Cement Based Materials With Cellulose Nanofibers, Parivash Takasi

Electronic Theses and Dissertations

Cellulose Nanofibers (CNFs) are used as additives in cement-based products to modify their properties. Recent studies about the effects of CNFs on cement paste showed inconsistent results for several different important properties, including compressive strength and free shrinkage. There is reason to believe that the unsystematic results of the compressive strengths were affected by the lack of uniform dispersion of CNFs. As a potential remedy, two different mixing methods were applied. The first method used a basic mixer, but aggregates were added to the cement paste mixture to improve the blending process. The second method utilized a high-speed shear mixer ...


Effective Exploration Behavior For Chemical-Sensing Robots, Kevin Nickels, Hoa Nguyen, Duncan M. Frasch, Timothy F. Davison 2019 Trinity University

Effective Exploration Behavior For Chemical-Sensing Robots, Kevin Nickels, Hoa Nguyen, Duncan M. Frasch, Timothy F. Davison

Engineering Faculty Research

Mobile robots that can effectively detect chemical effluents could be useful in a variety of situations, such as disaster relief or drug sniffing. Such a robot might mimic biological systems that exhibit chemotaxis, which is movement towards or away from a chemical stimulant in the environment. Some existing robotic exploration algorithms that mimic chemotaxis suffer from the problems of getting stuck in local maxima and becoming “lost”, or unable to find the chemical if there is no initial detection. We introduce the use of the RapidCell algorithm for mobile robots exploring regions with potentially detectable chemical concentrations. The RapidCell algorithm ...


Second-Harmonic Optical Vortex Conversion From Ws₂ Monolayer, Arindam Dasgupta, Jie Gao, Xiaodong Yang 2019 Missouri University of Science and Technology

Second-Harmonic Optical Vortex Conversion From Ws₂ Monolayer, Arindam Dasgupta, Jie Gao, Xiaodong Yang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Wavelength, polarization and orbital angular momentum of light are important degrees of freedom for processing and encoding information in optical communication. Over the years, the generation and conversion of orbital angular momentum in nonlinear optical media has found many novel applications in the context of optical communication and quantum information processing. With that hindsight, here orbital angular momentum conversion of optical vortices through second-harmonic generation from only one atomically thin WS2 monolayer is demonstrated at room temperature. Moreover, it is shown that the valley-contrasting physics associated with the nonlinear optical selection rule in WS2 monolayer precisely determines the output circular ...


Spontaneous Emission Rate Enhancement With Aperiodic Thue-Morse Multilayer, Ling Li, Cherian J. Mathai, Shubhra Gangopadhyay, Xiaodong Yang, Jie Gao 2019 Missouri University of Science and Technology

Spontaneous Emission Rate Enhancement With Aperiodic Thue-Morse Multilayer, Ling Li, Cherian J. Mathai, Shubhra Gangopadhyay, Xiaodong Yang, Jie Gao

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The emergence of multilayer metamaterials in the research field of enhancing spontaneous emission rates has recently received extensive attention. Previous research efforts mostly focus on periodic metal-dielectric multilayers in hyperbolic dispersion region; however, the influence of lattice order in subwavelength multilayers on spontaneous emission is rarely studied. Here, we observe the stronger Purcell enhancement of quantum dots coupled to the aperiodic metal-dielectric multilayer with Thue-Morse lattice order from elliptical to hyperbolic dispersion regions, compared to the periodic multilayer with the same metal filling ratio. This work demonstrates the potential of utilizing quasiperiodic metamaterial nanostructures to engineer the local density of ...


Hedge Fund Replication Using Strategy Specific Factors, Sujit Subhash, David Lee Enke 2019 Missouri University of Science and Technology

Hedge Fund Replication Using Strategy Specific Factors, Sujit Subhash, David Lee Enke

Engineering Management and Systems Engineering Faculty Research & Creative Works

Hedge funds have traditionally served wealthy individuals and institutional investors with the promise of delivering protection of capital and uncorrelated positive returns irrespective of market direction, allowing them to better manage portfolio risk. However, the financial crisis of 2008 has heightened investor sensitivity to the high fees, illiquidity, lack of transparency, and lockup periods typically associated with hedge funds. Hedge fund replication products, or clones, seek to answer these challenges by providing daily liquidity, transparency, and immediate exposure to a desired hedge fund strategy. Nonetheless, although lowering cost and adding simplicity by using a common set of factors, traditional replication ...


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