Matching Items (215)
Description
The OMFIT (One Modeling Framework for Integrated Tasks) modeling environment and the BRAINFUSE module have been deployed on the PPPL (Princeton Plasma Physics Laboratory) computing cluster with modifications that have rendered the application of artificial neural networks (NNs) to the TRANSP databases for the JET (Joint European Torus), TFTR (Tokamak Fusion Test Reactor), and NSTX (National Spherical Torus Experiment) devices possible through their use. This development has facilitated the investigation of NNs for predicting heat transport profiles in JET, TFTR, and NSTX, and has promoted additional investigations to discover how else NNs may be of use to scientists at PPPL. In applying NNs to the aforementioned devices for predicting heat transport, the primary goal of this endeavor is to reproduce the success shown in Meneghini et al. in using NNs for heat transport prediction in DIII-D. Being able to reproduce the results from is important because this in turn would provide scientists at PPPL with a quick and efficient toolset for reliably predicting heat transport profiles much faster than any existing computational methods allow; the progress towards this goal is outlined in this report, and potential additional applications of the NN framework are presented.
ContributorsLuna, Christopher Joseph (Author) / Tang, Wenbo (Thesis director) / Treacy, Michael (Committee member) / Orso, Meneghini (Committee member) / Barrett, The Honors College (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Department of Physics (Contributor)
Created2015-05
Description
Almost commuting matrices, i.e. matrices with a sufficiently small commutator, may be nearly commuting, i.e. there may exist matrices close by which do commute. By referencing current literature, this condition is studied for fixed dimension, unitary, self-adjoint, and orthogonal matrices. These proofs are made more accessible and compared to each other, providing insight to possible future progress in the field.
ContributorsMolloy, Riley Phillip (Author) / Spielberg, Jack (Thesis director) / Quigg, John (Committee member) / Barrett, The Honors College (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Department of Physics (Contributor)
Created2015-05
Description
Recently, electric and magnetic field sensing has come of interest to the military for a variety of applications, including imaging circuitry and detecting explosive devices. This thesis describes research at the ASU's Flexible Electronics and Display Center (FEDC) towards the development of a flexible electric and magnetic field imaging blanket. D-dot sensors, which detect changes in electric flux, were chosen for electric field sensing, and a single D-dot sensor in combination with a lock-in amplifier was used to detect individuals passing through an oscillating electric field. This was then developed into a 1 x 16 array of D-dot sensors used to image the field generated by two parallel wires. After the fabrication of a two-dimensional array, it was discovered that commercial field effect transistors did not have a high enough off-resistance to isolate the sensor form the column line. Three alternative solutions were proposed. The first was a one-dimensional array combined with a mechanical stepper to move the array across the E-field pattern. The second was a 1 x 16 strip detector combined with the techniques of computed tomography to reconstruct the image of the field. Such techniques include filtered back projection and algebraic iterative reconstruction (AIR). Lastly, an array of D-dot sensors was fabricated on a flexible substrate, enabled by the high off-resistance of the thin film transistors produced by the FEDC. The research on magnetic field imaging began with a feasibility study of three different types of magnetic field sensors: planar spiral inductors, Hall effect sensors, and giant magnetoresistance (GMR). An experimental array of these sensors was designed and fabricated, and the sensors were used to image the fringe fields of a Helmholtz coil. Furthermore, combining the inductors with the other two types of sensors resulted in three-dimensional sensors. From these measurements, it was determined that planar spiral inductors and Hall effect sensors are best suited for future imaging arrays.
ContributorsLarsen, Brett William (Author) / Allee, David (Thesis director) / Papandreou-Suppappola, Antonia (Committee member) / Barrett, The Honors College (Contributor) / Department of Physics (Contributor) / Electrical Engineering Program (Contributor)
Created2015-05
Description
In a pure spin current, electrons of opposite spins flow in opposite directions, thus information is conveyed by spin current without any charge current. This process almost causes no power consumption, which has the potential to realize ultra-low-power-consumption electronics. Recently, thermal effects in magnetic materials have attracted a great deal of attention because of its potential to generate pure spin currents using a thermal gradient (∇T), such as the spin Seebeck effect. However, unlike electric potential, the exact thermal gradient direction is experimentally difficult to control, which has already caused misinterpretation of the thermal effects in Py and Py/Pt films. In this work, we show that a well-defined ∇T can be created by two thermoelectric coolers (TECs) based on Peltier effect. The ∇T as well as its sign can be accurately controlled by the driven voltage on the TECs. Using a square-wave driven potential, thermal effects of a few μV can be measured. Using this technique, we have measured the anomalous Nernst effect in magnetic Co/Py and Py/Pt layers and determined their angular dependence. The angular dependence shows the same symmetry as the anomalous Hall effect in these films.
This work has been carried out under the guidance of the author’s thesis advisor, Professor Tingyong Chen.
This work has been carried out under the guidance of the author’s thesis advisor, Professor Tingyong Chen.
ContributorsSimaie, Salar (Author) / Chen, Tingyon (Thesis director) / Alizadeh, Iman (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor) / Department of Physics (Contributor)
Created2015-05
Description
Agent based models allow for complex results from simple parameters. The mobile agents in my model, the firms, are allocated an amount of capital, while the static agents, the workers, are allocated a range of wages. The firms are then allowed to move around and compete until they match with a worker that maximizes their production. It was found from the simulation that as competition increases so do wages. It was also found that when firms stay in the environment for longer that a higher wage is possible as a result of a larger window for drawn out competition. The different parameters result in a range of equilibriums that take variable amounts of time to reach. These results are interesting because they demonstrate that the mean wage is strongly dependent upon the window of time that firms are able to compete within. This type of model was useful because it demonstrated that there is a variation in the time dependence of the equilibrium. It also demonstrated that when there is very little entry and exiting of the market, that wage levels out at an equilibrium that is the same, regardless of the ratio between the number of firms and the number of workers. Further work to be done on this model includes the addition of a Matching Function so that firms and workers have a more fair agreement. I will also be adding parameters that allow for firms to see the workers around them so that firms are able to interact with multiple workers at the same time. Both of these alteration should improve the overall accuracy of the model.
ContributorsElledge, Jacob Morris (Author) / Veramendi, Gregory (Thesis director) / Murphy, Alvin (Committee member) / Department of Economics (Contributor) / Department of Physics (Contributor) / Barrett, The Honors College (Contributor)
Created2015-12
Description
Integration of dielectrics with graphene is essential to the fulfillment of graphene based electronic applications. While many dielectric deposition techniques exist, plasma enhanced atomic layer deposition (PEALD) is emerging as a technique to deposit ultrathin dielectric films with superior densities and interfaces. However, the degree to which PEALD on graphene can be achieved without plasma-induced graphene deterioration is not well understood. In this work, we investigate a range of plasma conditions across a single sample, characterizing both oxide growth and graphene deterioration using spectroscopic analysis and atomic force microscopy. Investigation of graphene and film quality produced by these conditions yields insight into plasma effects. Using a specially designed sample configuration, we achieve ultrathin (< 1 nm) aluminum oxide films atop graphene.
ContributorsTrimble, Christie Jordan (Author) / Nemanich, Robert (Thesis director) / Zaniewski, Anna (Committee member) / Department of Physics (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Covering subsequences with sets of permutations arises in many applications, including event-sequence testing. Given a set of subsequences to cover, one is often interested in knowing the fewest number of permutations required to cover each subsequence, and in finding an explicit construction of such a set of permutations that has size close to or equal to the minimum possible. The construction of such permutation coverings has proven to be computationally difficult. While many examples for permutations of small length have been found, and strong asymptotic behavior is known, there are few explicit constructions for permutations of intermediate lengths. Most of these are generated from scratch using greedy algorithms. We explore a different approach here. Starting with a set of permutations with the desired coverage properties, we compute local changes to individual permutations that retain the total coverage of the set. By choosing these local changes so as to make one permutation less "essential" in maintaining the coverage of the set, our method attempts to make a permutation completely non-essential, so it can be removed without sacrificing total coverage. We develop a post-optimization method to do this and present results on sequence covering arrays and other types of permutation covering problems demonstrating that it is surprisingly effective.
ContributorsMurray, Patrick Charles (Author) / Colbourn, Charles (Thesis director) / Czygrinow, Andrzej (Committee member) / Barrett, The Honors College (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Department of Physics (Contributor)
Created2014-12
Description
In fan fiction, fans utilize different elements in an original work and incorporate them into their fanfics; elements such as the characters and setting of an original work are frequently used in fan fiction. A different element is investigated: time travel. The physics behind time travel is not yet understood, so authors have to create their own time travel physics in their works to account for this lack of understanding. Therefore, for fan authors to incorporate time travel into their fanfic, they must study the time travel physics in the original work the same way that characters from an original work are studied. Three original works and three fanfics are examined: the television show My Little Pony: Friendship is Magic and its fanfic "The Fall and Rise of the Alicorn", the Harry Potter book series and its fanfic "Back to the Time of the Unknown", and the webcomic Homestuck and its fanfic "Like a Bug on a Windshield".
ContributorsClark, Michael Robert (Author) / Ingram-Waters, Mary (Thesis director) / Scott, Suzanne (Committee member) / Barrett, The Honors College (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Department of Physics (Contributor)
Created2014-05
Description
In this experiment, an attempt was made to measure the index of refraction of a thin glass microscope slide, with a known thickness of 1.01 mm. A monochromatic laser with wavelength of 532nm was employed to generate the interference pattern through the use of a Michelson interferometer. The slide was placed in the path of one of the beams. The slide could then be rotated through a series of angles, and, from the resulting changes in the interference pattern, the index of refraction of the slide could be extracted. The index of refraction was found to be 1.5±0.02.
ContributorsSwenson, Jordan (Author) / Sukharev, Maxim (Thesis director) / Bennett, Peter (Committee member) / Barrett, The Honors College (Contributor) / Department of Physics (Contributor)
Created2014-05
Description
Computer simulations are gaining recognition as educational tools, but in general there is still a line dividing a simulation from a game. Yet as many recent and successful video games heavily involve simulations (SimCity comes to mind), there is not only the growing question of whether games can be used for educational purposes, but also of how a game might qualify as educational. Endemic: The Agent is a project that tries to bridge the gap between educational simulations and educational games. This paper outlines the creation of the project and the characteristics that make it an educational tool, a simulation, and a game.
ContributorsFish, Derek Austin (Author) / Karr, Timothy (Thesis director) / Marcus, Andrew (Committee member) / Jones, Donald (Committee member) / Barrett, The Honors College (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Department of Physics (Contributor)
Created2013-05