Thesis/Capstone Archive

Year:
Advisor:
Jacob Barker (Senior Thesis, March 2019, Advisor: Justin Peatross )

Abstract

A focused intense laser pulse can rip multiple electrons from atoms. At low density,the liberated electrons move freely in the laser field in response to the Lorentz force. The movement of a charged particle causes electromagnetic radiation to scatter out of the focus. In our lab, we study these laser-particle interactions by looking at the scattered electromagnetic radiation. As the laser intensity increases, electrons can reach relativistic speeds as they oscillate. Few people have intuition for this complex motion and radiation. I developed a computer simulation that animates these interactions in a physically realistic manner. I discuss the physics of these interaction and the development of the simulation. I present several animations of scenarios similar to our experiments

Adam Bugg (Senior Thesis, April 2019, Advisor: Eric Hintz )

Abstract

Spectroscopic observations from the Dominion Astrophysical Observatory of the Cepheid X Cyg show that the star underwent a temperature shift and phase transition sometime between 2013 and 2014. As follow-up work, we conducted a photometric campaign to monitor X Cyg and a collection of 40 other Cepheids, measuring their temperature via a set of Ha filters in addition to the Johnson V filter. While phasing observations in the V filter reproduced clear light curves, Ha light curves were far less successful. The greatest hindrance to properly measuring Ha indices was likely poor signal-to-noise in the narrow Ha filter; the 8-inch telescope used may simply be unable to collect enough light. Accumulating more data, however, would likely reduce scatter and tighten up the results.

Alex Cahoon (Capstone, April 2019, Advisor: Karine Chesnel )

Abstract

The Surface Magneto-Optical Kerr Effect (SMOKE) magnetometer is an instrument used to measure the out-of-plane magnetization of thin films made of ferromagnetic materials using polarized visible light. It does this by taking advantage of the Kerr effect which is a magnetic-optical interaction where the polarization of the light reflected from a magnetic surface is rotated approximately proportionally to the amount of magnetization in the material. We use the instrument to map hysteresis loops in ferromagnetic thin film multilayers by applying a varying external magnetic field to the sample while simultaneously measuring the polarization rotation. My project has consisted of upgrading the physical SMOKE apparatus: we have improved the mechanical stability and introduced new features that will allow us to alter the incident angle between the sample and the polarized light, as well as give us the ability to translate samples so that we can study different sections of the samples without having to remount them.

Damyn Chipman (Capstone, April 2019, Advisor: )

Abstract

Computational models that accurately describe the physics in fluid domains are essential in the design process of aircraft. These models are used as tools to quickly design, model, test, and optimize aircraft. However, many current mathematical models are too computationally taxing. Optimization of many of these Eulerian, or mesh-based, methods is infeasible, due to the high wall time for each call to the model. Our approach is to use Lagrangian methods, which have the potential of reduced wall time and increased numerical accuracy. The Vortex Particle Method (VPM) is a Lagrangian formulation of the vorticity form of the Naiver-Stokes (NS) equations put together by Alvarez et al [1]. While the VPM is capable of solving the NS equations in a field, boundary conditions must be imposed separately. The purpose of this thesis is to present an approach to introducing boundary information through the calculation of a vortex sheet on a surface required to induce the no-slip boundary condition. The resulting vorticity is then introduced to the vorticity field through the solution of a diffusion equation. This Vortex Sheet Boundary (VSB) Method is presented and verified, and the results are discussed.

Daniel Johnston (Capstone, April 2019, Advisor: )

Abstract

Influenza A is responsible for the death of an average of 85 000 people per year in the western hemisphere and the hospitalization of many more. Currently-available anti-influenza drugs were designed to target the M2 proton channel and disrupt the process of viral replication but widespread mutations to the M2 channel have rendered these drugs generally ineffective. In preparation for the event of a flu pandemic a new class of anti-influenza drugs is needed. Copper ions have been shown to successfully block the M2 channel and in this paper several novel compounds are complexed with copper and tested as potential M2 inhibitors via electrophysiology tests and miniplaque assays. The results show that several neutral compounds successfully block mutant and wild type viruses in oocyte studies. However, animal tests show no efficacy. Divalent compounds are shown to be ineffective in all cases. Monovalent compounds are hypothesized to be the best suited to M2 inhibition due to the channel’s design, which is intended to transport monovalent protons. Future studies should include further testing of monovalent copper complexes.

Christian Lambert (Senior Thesis, February 2019, Advisor: Manuel Berrondo )

Abstract

Emergent behavior - behavior exhibited by groups that is not seen in individuals - is a critical part of our world and is difficult to model well. We present a dynamic model where a flock of simulated birds (boids) exists in two dimensions. Each boid has a constant speed and a fixed randomly determined number of neighbors, defined as those boids that influence the direction of its motion (consensus). Modifications of the boids’ flight following a specific algorithm (frustration) during the simulation results in emergent behavior. The flock of boids is mapped to a directed graph. Changing the boids’ neighbors also modifies the graph. Rigorously defined sub-flocks are identified using graph theory. Using a new method of frustration, α turns, we can enhance the emergent behavior exhibited. Analyzing this emergent behavior is done through order parameters that help us understand how ordered the flock or sub-groups of the flock are. Analyzing the mapping of the graph to the flock can expand our understanding of how and when dynamic emergence occurs in this flocking model. This is done by showing how physical the model is in whether the flock splits like we see real flocks of birds doing. Using α turns and the nearest neighbor consensus method we find we have emergent behavior within a specific range of the model parameters.

Jared Miller (Capstone, April 2019, Advisor: Scott Sommerfeldt )

Abstract

There has always been a significant population concerned with achieving the best possible environment for listening to music; but in our world of convenience, people don’t want to have to go to the symphony hall to enjoy such an experience. The research presented here uses active noise control to alter sound produced in a given environment, in order to match a more desirable listening environment. This is done by incorporating a measured acoustic impulse response, representing the desired listening environment, into a filtered-x algorithm. The algorithm adapts until the response in the actual listening space matches the response of the desired listening space. Creating a computational simulation allowed for rigorous testing of the algorithm. Once the algorithm was fine tuned through the simulated testing, it could be applied in a physical system. Initial physical testing shows promising results, so further investigations are recommended.

Michael Nelson (Senior Thesis, April 2019, Advisor: Lawrence Rees )

Abstract

Frequently, in nuclear physics research, nuclear events are studied using the electrical or optical signals they produce in various materials. Research relating to neutrons has an especially strong need for robust and efficient signal classification algorithms that can be adapted quickly to varying materials and experiment types. Previous methods are considered, and a new graphically-driven software-based pulse shape discrimination approach is proposed. Our implementation of the method is explained in detail. Use of the method at BYU has significantly reduced the time required to begin new neutron-related research projects and adapt to changes in experimental setup. Furthermore, it has dramatically increased user understanding of the pulse classification process, reduced the number of errors made, and helped identify mistakes made in processing previous datasets.

Christoph Schulzke (Senior Thesis, January 2019, Advisor: Justin Peatross )

Abstract

Electrons driven by intense laser fields exhibit nonlinear Thomson scattering. Measuring these radiation patterns has become of interest to many groups including our group at Brigham Young University.The theoretical description of this phenomenon was outlined by Sarachik and Schappert in 1970. The solution for the scattered light involves a numeric integral. They developed an approximation which uses a series of Bessel functions in place of the integral. In this thesis we investigate the efficacy of the Bessel-series approximation to see if gives an advantage over the numerical-integration approach. We find only a modest advantage for certain parameters. Generally, performing the integration numerically is a sensible approach.