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Investigation Of The Skin Effect In Alternating Currents, Matthew Liang 2018 School of Science and Technology Singapore

Investigation Of The Skin Effect In Alternating Currents, Matthew Liang

The International Student Science Fair 2018

My research is on the investigation of the skin effect in alternating currents. The skin effect is when an alternating current tends to flow on the surface of the conductor, such that the current density is highest near the surface, and decreases with greater depths in the conductor. This is due to the alternating current inducing changing magnetic fields, which in turn induces currents that oppose the original flow of current, resisting the current flowing through the centre the most. This reduces the effective cross-sectional area of the conductor and increases the resistance, causing increased power losses. This effect becomes ...


Energy Conversion System For Travelers (Ecost), Thipok Bovornratanaraks 2018 Chulalongkorn University Demonstration Secondary School

Energy Conversion System For Travelers (Ecost), Thipok Bovornratanaraks

The International Student Science Fair 2018

We have innovated “The Energy Conversion System for Travelers” or the ECoST. With the fact that most travelers have wheeled cabin-bags, whilst walking, the wheels will rotate so why don’t we harvest electricity from this kinetic energy? We thus install our innovation, the ECoST, to the bag to generate electricity from the spinning wheels. The electricity is then kept in the storage unit and ready to charge your empty battery devices in an emergency case via a USB port. To make life easy, our ECoST was designed to replicate the power bank charging method; therefore, we can charge it ...


Modeling Recombination In Solar Cells, Paul Chery 2018 Macalester College

Modeling Recombination In Solar Cells, Paul Chery

Macalester Journal of Physics and Astronomy

Solar cells are a competitive alternative to nonrenewable energy sources such as fossil fuels. However, the efficiency of these devices is limited by photogenerated carrier recombination. We use a finite difference numerical model to study recombination phenomena in the absorber layer of solar cells including alternate recombination models and the effects of spatial distribution of recombination centers. We compare the effect of using the constant lifetime approximation for recombination to the full Shockley-Read-Hall expression in Silicon solar cells and find that the constant lifetime approximation holds for high defect densities but not for high photon flux densities. Finally, we simulate ...


Investigation Of The Skin Effect In Alternating Currents, Matthew Liang 2018 School of Science and Technology Singapore

Investigation Of The Skin Effect In Alternating Currents, Matthew Liang

The International Student Science Fair 2018

My research is on the investigation of the skin effect in alternating currents. My project is broken down into 4 sub-aims. The first aim would be, to be able to mathematically model the distribution of current in the radius of the wire, which consists of the applications of the Maxwell equation and solving zeroth order differential Bessel equations of the first kind. The next aim would be to computationally plot out the desired current readings as the depth of the wire increases from the surface, using the Matlab software. The third aim that I have would be conducting an experiment ...


Energy Conversion System For Travelers (Ecost), Thipok Bovornratanaraks 2018 Chulalongkorn University Demonstration Secondary School

Energy Conversion System For Travelers (Ecost), Thipok Bovornratanaraks

The International Student Science Fair 2018

We have innovated “The Energy Conversion System for Travelers” or the ECoST. With the fact that most travelers have wheeled cabin-bags, whilst walking, the wheels will rotate so why don’t we harvest electricity from this kinetic energy? We thus install our innovation, the ECoST, to the bag to generate electricity from the spinning wheels. The electricity is then kept in the storage unit and ready to charge your empty battery devices in an emergency case via a USB port. To make life easy, our ECoST was designed to replicate the power bank charging method; therefore, we can charge it ...


Augustana Invitational Robotics Challenge 2018, Forrest Stonedahl 2018 Augustana College, Rock Island Illinois

Augustana Invitational Robotics Challenge 2018, Forrest Stonedahl

Celebration of Learning

We will be hosting the 3rd Annual Augustana Invitational Robotics Challenge. This event will involve student teams from Augustana and potentially several other schools in the region bringing forth the robots that they have designed, built, and programmed, to compete against one another. This year's challenge task involves the careful relocation of soda pop cans.


Phase Field Study Of Surface-Induced Melting And Solidification From A Nanovoid: Effect Of Dimensionless Width Of Void Surface And Void Size, Anup Basak, Valery I. Levitas 2018 Iowa State University

Phase Field Study Of Surface-Induced Melting And Solidification From A Nanovoid: Effect Of Dimensionless Width Of Void Surface And Void Size, Anup Basak, Valery I. Levitas

Physics and Astronomy Publications

The size effect and the effects of a finite-width surface on barrierless transformations between the solid (S), surface melt (SM), and melt (M) from a spherical nanovoid are studied using a phase field approach. Melting (SM → M and S → M) from the nanovoid occurs at temperatures which are significantly greater than the solid-melt equilibrium temperature θe but well below the critical temperature for solid instability. The relationships between the SM and M temperatures and the ratio of the void surface width and width of the solid-melt interface, Δ⎯⎯⎯, are found for the nanovoids of different sizes. Below a critical ratio ...


Mesoscale Computational Studies Of Thin-Film Bijels, Joseph M. Carmack 2018 University of Arkansas, Fayetteville

Mesoscale Computational Studies Of Thin-Film Bijels, Joseph M. Carmack

Theses and Dissertations

Bijels are a relatively new class of soft materials that have many potential applications in the technology areas of energy, medicine, and environmental sustainability. They are formed by the arrest of binary liquid spinodal decomposition by a dispersion of solid colloidal nanoparticles. This dissertation presents an in-depth simulation study of Bijels constrained to thin-film geometries and in the presence of electric fields. We validate the computational model by comparing simulation results with previous computational modeling and experimental research. In the absence of suspended particles, we demonstrate that the model accurately captures the rich kinetics associated with diffusion-based surface-directed spinodal decomposition ...


Synthesis And Characterization Of Ca-Doped Lamnaso, Yong Liu, Warren E. Straszheim, Pinaki Das, Farhan Islam, Thomas W. Heitmann, Robert McQueeney, David Vaknin 2018 Ames Laboratory

Synthesis And Characterization Of Ca-Doped Lamnaso, Yong Liu, Warren E. Straszheim, Pinaki Das, Farhan Islam, Thomas W. Heitmann, Robert Mcqueeney, David Vaknin

Ames Laboratory Accepted Manuscripts

We report on our attempt to hole-dope the antiferromagnetic semiconductor LaMnAsO by substitution of the La3+ site by Ca2+. We use neutron and x-ray diffraction, magnetic susceptibility, and transport techniques to characterize polycrystalline (La1−xCax)MnAsO samples prepared by solid-state reaction and find that the parent compound is highly resistant to substitution with an upper limit x≤0.01. Magnetic susceptibility of the parent and the x=0.002(xnom=0.04) compounds indicate a negligible presence of magnetic impurities (i.e., MnO or MnAs). Rietveld analysis of neutron and x-ray diffraction data shows the preservation of both the tetragonal ...


Measuring The Double Layer Capacitance Of Electrolytes With Varied Concentrations, Geoffrey Rath 2018 Linfield College

Measuring The Double Layer Capacitance Of Electrolytes With Varied Concentrations, Geoffrey Rath

Senior Theses

When electric potentials are applied from an electrolytic fluid to a metal, a double layer capacitor, Cdl, develops at the interface. The layer directly at the interface is called the Stern layer and has a thickness equal to roughly the size of the ions in the fluid. The next layer, the diffuse layer, arises from the gathering of like charges in the Stern layer. This layer is the distance needed for ionic charges to return to equilibrium. This distance, called the Debye length, λ, depends on the square root of the electrolyte concentration. To study the properties of the ...


Effects Of Tension On Resonant Frequencies Of Strings, Blake Burnett 2018 Linfield College

Effects Of Tension On Resonant Frequencies Of Strings, Blake Burnett

Senior Theses

This project tests and explores resonance of strings. Since all materials and mechanisms are affected by vibrations, it is important to know the frequencies at which resonance occurs. To explore this subject, strings were used as a model material to test the effect tension has on resonance. The fundamental frequencies and the corresponding modes of resonance were used to analyze the data. The results of this experiment show that increasing tension on a string increases its resonance frequency. Understanding the physics behind resonance frequency allows systems to be designed to take advantage of resonance properties, or to avoid resonance where ...


The Drag Coefficient Of Varying Dimple Patterns, James M. Seeley, Michael S. Crosser 2018 Linfield College

The Drag Coefficient Of Varying Dimple Patterns, James M. Seeley, Michael S. Crosser

Senior Theses

There are many golf balls on the market today with varying dimple sizes, shapes, and distribution. These proprietary differences are all designed to reduce drag on the balls during flight, allowing golfers to hit the ball farther distances. There are limited published studies comparing how varying the dimples affects the reduction of drag. An experiment was developed in which golf balls were pulled through a water tank to measure the drag force acting on each ball. The water was chosen to allow for testing at slower velocities than the typical necessary speeds to cause turbulence for balls traveling in air ...


Increasing The Longevity Of Tungsten Filaments In A Zone Refiner, Byron D. Greenlee 2018 Linfield College

Increasing The Longevity Of Tungsten Filaments In A Zone Refiner, Byron D. Greenlee

Senior Theses

Zone refining is used for its ability to purify material and grow single crystals. To produce these single crystals, a suspended molten zone, generated by electron bombardment, passes along the polycrystalline stock. During a zone refining run, the filaments that produce the electron bombardment can fail. In this project, the longevity of tungsten filaments in a zone refiner was investigated. A new bombardment geometry was constructed to attempt to increase the longevity of the filaments. The new geometry had a shield machined into it to prevent line-of-sight impurities originating in the molten zone from striking the filaments. It was found ...


The Effects Of Surface Pace In Baseball, Jason Farlow 2018 Linfield College

The Effects Of Surface Pace In Baseball, Jason Farlow

Senior Theses

A baseball travels across different surfaces at different paces. The goal of this experiment is to find a percentage difference in speeds the ball will reflect off a given surface. The energy lost on the turf surface was far more significant than on dirt surface as the turf lost an average of 26% of its energy as compared to just 16% of the energy on dirt. In the Northwest conference, teams play on four turf-based infields and five dirt-based infields. The results of this study suggest that kinetic friction forces are more significant in reducing ball rebound speed than in ...


Synthesis Of Two-Dimensional Materials Development And Automation Of An Ultra-High Vacuum System, Mayuka Sasaki 2018 The College at Brockport

Synthesis Of Two-Dimensional Materials Development And Automation Of An Ultra-High Vacuum System, Mayuka Sasaki

Senior Honors Theses

Graphene is a two-dimensional (2D) semi-metal material consisting of a single layer of carbon. Due to its interesting and unique electrical, optical, thermal, and mechanical properties, synthesis of high quality graphene is essential in the development of devices that make use of 2D material properties. One way to study graphene growth is in an ultra-high vacuum (UHV) chamber. In order to get an ideally low pressure for the graphene growth, the whole chamber needs to be heated up to above 100℃ for a several days (bakeout). After bakeout, silicon carbide (SiC) substrate can be used for graphene growth with being ...


Numerical Simulation Of A High Strain Rate Biaxial Compression Apparatus, Michael Lagieski 2018 Washington University in St. Louis

Numerical Simulation Of A High Strain Rate Biaxial Compression Apparatus, Michael Lagieski

Engineering and Applied Science Theses & Dissertations

Few experimental methods today are capable of exploring the strength of materials at high strain rates (105 s-1). Those that are capable, such as the Split Hopkinson Bar, Taylor Anvil and Plate Impact suffer from instability and are generally limited to one dimensional wave propagation. Of particular interest is material response under biaxial compression, similar to that seen in inertial confinement fusion. Laser fusion fuel pellets typically undergo large strain rates as well as plastic deformation and non-linear behavior. This work briefly outlines an experimental procedure designed to replicate these large strain rates under biaxial compression using spherical ...


Characterization Of Magnetic Thin Films Using The Magneto Optic Kerr Effect, Nicholas J. Savino 2018 Lynchburg College

Characterization Of Magnetic Thin Films Using The Magneto Optic Kerr Effect, Nicholas J. Savino

Student Scholar Showcase

Understanding magnetic properties of materials allows for advances in applications such as data storage. The Magneto-Optic Kerr Effect (MOKE) displays the reflective response a magnetic material has to a magnetic field. When polarized light reflects off of a magnetic material, the polarization orientation can change. The application of an external magnetic field can affect how much this polarization changes in a non-linear manner. Hysteresis loops are created when examining the relationship between intensity of the reflected light to the applied magnetic field provide information about magnetic properties of that material, such as the coercive field and field retention. Preliminary measurements ...


Hedgehog Spin-Vortex Crystal Stabilized In A Hole-Doped Iron-Based Superconductor, William R. Meier, Qing-Ping Ding, Andreas Kreyssig, Sergey Bud’ko, Aashish Sapkota, Karunakar Kothapalli, Vladislav Borisov, Roser Valentí, Cristian D. Batista, Peter Orth, Rafael M. Fernandes, Alan I. Goldman, Yuji Furukawa, Anna E. Böhmer, Paul C. Canfield 2018 Iowa State University and Ames Laboratory

Hedgehog Spin-Vortex Crystal Stabilized In A Hole-Doped Iron-Based Superconductor, William R. Meier, Qing-Ping Ding, Andreas Kreyssig, Sergey Bud’Ko, Aashish Sapkota, Karunakar Kothapalli, Vladislav Borisov, Roser Valentí, Cristian D. Batista, Peter Orth, Rafael M. Fernandes, Alan I. Goldman, Yuji Furukawa, Anna E. Böhmer, Paul C. Canfield

Ames Laboratory Accepted Manuscripts

Magnetism is widely considered to be a key ingredient of unconventional superconductivity. In contrast to cuprate high-temperature superconductors, antiferromagnetism in most Fe-based superconductors (FeSCs) is characterized by a pair of magnetic propagation vectors, (π,0) and (0,π). Consequently, three different types of magnetic order are possible. Of these, only stripe-type spin-density wave (SSDW) and spin-charge-density wave (SCDW) orders have been observed. A realization of the proposed spin-vortex crystal (SVC) order is noticeably absent. We report a magnetic phase consistent with the hedgehog variation of SVC order in Ni-doped and Co-doped CaKFe 4As 4 based on thermodynamic, transport, structural and ...


An Open-Source Quadrature-Based Population Balance Solver For Openfoam, Alberto Passalacqua, Frédérique Laurent, Ehsan Madadi-Kandjani, Jeffrey C. Heylmun, Rodney O. Fox 2018 Iowa State University

An Open-Source Quadrature-Based Population Balance Solver For Openfoam, Alberto Passalacqua, Frédérique Laurent, Ehsan Madadi-Kandjani, Jeffrey C. Heylmun, Rodney O. Fox

Chemical and Biological Engineering Publications

The extended quadrature method of moments (EQMOM) for the solution of population balance equations (PBE) is implemented in the open-source computational fluid dynamic (CFD) toolbox OpenFOAM as part of the OpenQBMM project. The moment inversion procedure was designed (Nguyen et al., 2016) to maximize the number of conserved moments in the transported moment set. The algorithm is implemented in a general structure to allow the addition of other kernel density functions defined on R+, and arbitrary kernels to describe physical phenomena involved in the evolution of the number density function. The implementation is verified with a set of zero-dimensional cases ...


Nucleation Of Stoichiometric Compounds From Liquid: Role Of The Kinetic Factor, Huajing Song, Yang Sun, Feng Zhang, Cai-Zhuang Wang, Kai-Ming Ho, Mikhail I. Mendelev 2018 Ames Laboratory

Nucleation Of Stoichiometric Compounds From Liquid: Role Of The Kinetic Factor, Huajing Song, Yang Sun, Feng Zhang, Cai-Zhuang Wang, Kai-Ming Ho, Mikhail I. Mendelev

Ames Laboratory Accepted Manuscripts

The nucleation rate depends on the free-energy barrier and the kinetic factor. While the role of the free energy barrier is a text-book subject, the importance of the kinetic factor is frequently underestimated. In this study, we applied the mean first-passage time method, to obtain the free-energy landscape and kinetic factor directly from the molecular dynamics (MD) simulations of the nucleation of the face-centered cubic (fcc) phase in the pure Ni and the B2 phases in the N i 50 A l 50 and C u 50 Z r 50 alloys. The obtained data show that while the free-energy barrier ...


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