Physical Sciences and Mathematics Commons^™

Order And Harmony: Kepler’S Guiding Forces, Dan Broadbent

Faculty Publications

Adapted from the article “Order and Harmony: Kepler’s Guiding Forces” included in “Towards Mysteries of the Cosmos with Johannes Kepler – on the 450th Anniversary of His Birth,” a commemorative volume published by the Obserwatorium Atronommiczne Krolowej Jadwigi Rzepienniku Biskupim (Queen Jadwiga Observatory of Rzepiennik Biskupi Poland) December 2021. Adapted with permission.

As the subject librarian for physics and astronomy at Brigham Young University, the author has had the privilege of handling some of Johannes Kepler’s original books preserved in the university’s archives. One of the most impressive materials in the archive is a large page from Mysterium Cosmographicum that …

Light And Truth: Measuring Unseen Harm In Individuals And Communities, Hannah Pfost

Undergraduate Honors Theses

While the fields of physics and international development may seem disparate, the insights gained from studying each one of them can improve understanding of the other. Here, I demonstrate that concept as applied to computational optics and historical memory. Thus, the purpose of this project is threefold: (1) to computationally model light transport through tissue, and use that model to inform choices about a physical system; (2) to determine the types of historical memory recommended in the final reports of truth commissions; and (3) to give evidence for the usefulness of human-centered design in both areas. To model light transport, …

Computational Development Of A Miniature Quantum Dot Spectrometer For Use In Space, Joseph Richardson

Undergraduate Honors Theses

Miniature spectrometers are of great interest to NASA as necessary instrumentation is scaled down and optimized for specific space application. Semiconductor nanocrystals called quantum dots (QD) are being used to create a miniature high-resolution filter-based spectrometer, with the goal of use in space within 5 years. Computational imaging techniques— such as automated image analysis and mathematical spectrum reconstruction algorithms—are key to making the QD spectrometer a reality. This thesis will discuss the process of developing these computational methods, along with the improvements that have occurred from previous work.

Emergent Properties Of The Transport Of Sand, Eric Lenhart

Undergraduate Honors Theses

In the interest of drawing conclusions about Aeolian environments based on remote imaging, we investigated how air flow forms self-organizing patterns, such as ripples, across loose particulate surfaces. Specifically, we analyzed various models of sand transport, particularly Nishimori’s model, to note the effects of altering various parameters, including wind direction, saltation length, diffusion, and a saltation proportionality constant. As a measure of the frustration of the emergent patterns, Y-junctions were counted at various values of the parameters. A strong correlation with the saltation proportionality constant and no correlation with the saltation height were found. As an additional use of the …

Using Coherence To Improve The Calculation Of Active Acoustic Intensity With The Phase And Amplitude Gradient Estimator Method, Mylan Ray Cook

Theses and Dissertations

Coherence, which gives the similarity of signals received at two microphone locations, can be a powerful tool for calculating acoustic quantities, particularly active acoustic intensity. To calculate active acoustic intensity, a multi-microphone probe is often used, and therefore coherence between all microphone pairs on the probe can be obtained. The phase and amplitude gradient estimator (PAGE) method can be used to calculate intensity, and is well suited for many situations. There are limitations to this method—such as multiple sources or contaminating noise in the sound field—which can cause significant error. When there are multiple sources or contaminating noise present, the …

Writing And Designing A Chapter On Mercury And Pluto For The Textbook Exploring The Planets (Explanet.Info), Braxton Clark Spilker

Theses and Dissertations

Exploring the Planets (http://explanet.info) is a free online college textbook covering thebasic concepts of planetary science emphasizing the character and evolution of the planetarybodies in the Solar System. The latest edition (3rd edition) was published online in 2007 by EricH Christiansen. Since the release of the third edition, two important planetary missions havebeen completed: MESSENGER (to Mercury) and New Horizons (to Pluto). These missionsprovided new information and fundamental insights into these planetary bodies, which have notyet been included in Exploring the Planets. The modern results based on recent investigations ofMercury and Pluto are critical for our understanding of the nature …

Fitting Parameter Uncertainties In Least Squares Fitting, R. Steven Turley

Faculty Publications

This article review the theory and practice of computing uncertainties in the fit parameters in least squares fits. It shows how to estimate the uncertainties and gives some numerical examples in Julia of their use. Examples are given and validated for both linear and nonlinear fits.

Polynomial Fitting, R. Steven Turley

Faculty Publications

This article reviews the theory and some good practice for fitting polynomials to data. I show by theory and example why fitting using a basis of orthogonal polynomials rather than monomials is desirable. I also show how to scale the independent variable for a more stable fit. I also demonstrate how to compute the uncertainty in the fit parameters. Finally, I discuss regression analysis: how to determine whether adding an additional term to the fit is justified.

Ion Friction At Small Values Of The Coulomb Logarithm, Robert Tucker Sprenkle

Theses and Dissertations

We create a dual-species ultracold neutral plasma (UNP) by photo-ionizing Yb and Ca atoms in a dual-species magneto-optical trap. Unlike single-species UNP expansion, these plasmas are well outside of the collisionless (Vlasov) approximation. We observe the mutual interaction of the Yb and Ca ions by measuring the velocity distribution for each ion species separately. We model the expansion using a fluid code including ion-ion friction and compare with experimental results to obtain a value of the Coulomb logarithm of Λ= 0.04.

Use Of Phase And Amplitude Gradient Estimation For Acoustic Source Characterization And Localization, Joseph Scott Lawrence

Theses and Dissertations

Energy-based acoustic quantities provide vital information about acoustic fields and the characterization of acoustic sources. Recently, the phase and amplitude gradient estimator (PAGE) method has been developed to reduce error and extend bandwidth of energy-based quantity estimates. To inform uses and applications of the method, analytical and experimental characterizations of the method are presented. Analytical PAGE method bias errors are compared with those of traditional estimation for two- and three-microphone one-dimensional probes. For a monopole field when phase unwrapping is possible, zero bias error is achieved for active intensity using three-microphone PAGE and for specific acoustic impedance using two-microphone PAGE. …

Thin Film Carbon Nanofuses For Permanent Data Storage, Kevin Robert Laughlin

Theses and Dissertations

We have fabricated nanofuses from thin-film, arc-evaporation carbon for use in permanent data storage. Thin film carbon fuses have fewer fabrication barriers and retain the required resistivity and structural stability to work as a data storage medium. Carbon thin films were characterized for their electrical, microstructural, and chemical bonding properties. Annealing the thin-film carbon in an argon environment at 400°C reduced the resistivity from about 4*10^-2 Ω cm as deposited down to about 5*10^-4 Ω cm, allowing a lower blowing voltage. Nanofuses with widths ranging from 200 nm down to 60 nm were fabricated and tested. They blow …

Development Of A Real-Time Auralization System For Assessment Of Vocal Effort In Virtual-Acoustic Environments, Jennifer Kay Whiting

Theses and Dissertations

This thesis describes the development of the real-time convolution system (RTCS) for a little-studied talker/listener in virtual acoustic environments. We include descriptions of the high-resolution directivity measurements of human speech, the RTCS system components, the measurement and characterization of oral-binaural room impulse responses (OBRIRs) for a variety of acoustic environments, and the compensation filter necessary for its validity. In addition to incorporating the high-resolution directivity measurements, this RTCS improved on that developed by Cabrera et al. [1] through the derivation and inclusion of the compensation filter. Objective measures in the time- and frequency-domains, as well as subjective measures, were developed …

Evaporated Aluminum Fluoride As A Barrier Layer To Retard Oxidation Of Aluminum Mirrors, Margaret Miles

Theses and Dissertations

The aluminum oxide growth rate for aluminum protected with 2.4 nm of aluminum fluoride has been determined. We show that a 2.4 nm aluminum fluoride layer does not prevent aluminum from oxidation but does significantly retard the oxide growth – decreasing the oxide layer thickness from 1 nm in less than an hour to 0.9 nm over 116 hours. Additionally, the optical constants for aluminum oxide growing under an aluminum fluoride barrier layer have been determined – showing an increase in absorption at high energies for Al₂O₃ forming at room temperature as compared to highly ordered Al …

The Morphology And Uniformity Of Circumstellar Oh/H2O Masers Around Oh/Ir Stars, Derek Sean Felli

Theses and Dissertations

Even though low mass stars (< 8 solar masses) vastly outnumber high mass stars (< 8 solar masses), the more massive stars drive the chemical evolution of galaxies from which the next generation of stars and planets can form. Understanding mass loss of asymptotic giant branch stars contributes to our understanding of the chemical evolution of the galaxy, stellar populations, and star formation history. Stars with mass < 8 solar masses form planetary nebulae, while those with mass < 8 solar masses go supernova. In both cases, these stars enrich their environments with elements heavier than simple hydrogen and helium molecules. While some general info about how stars die and form planetary nebulae are known, specific details are missing due to a lack of high-resolution observations and analysis of the intermediate stages. For example, we know that mass loss in stars creates morphologically diverse planetary nebulae, but we do not know the uniformity of these processes, and therefore lack detailed models to better predict how spherically symmetric stars form asymmetric nebulae. We have selected a specific group of late-stage stars and observed them at different scales to reveal the uniformity of mass loss through different layers close to the star. This includes observing nearby masers that trace the molecular shell structure around these stars. This study revealed detailed structure that was analyzed for uniformity to place constraints on how the mass loss processes behave in models. These results will feed into our ability to create more detailed models to better predict the chemical evolution of the next generation of stars and planets.

Machine Learning To Discover And Optimize Materials, Conrad Waldhar Rosenbrock

Theses and Dissertations

For centuries, scientists have dreamed of creating materials by design. Rather than discovery by accident, bespoke materials could be tailored to fulfill specific technological needs. Quantum theory and computational methods are essentially equal to the task, and computational power is the new bottleneck. Machine learning has the potential to solve that problem by approximating material behavior at multiple length scales. A full end-to-end solution must allow us to approximate the quantum mechanics, microstructure and engineering tasks well enough to be predictive in the real world. In this dissertation, I present algorithms and methodology to address some of these problems at …

Oxidization Of Al And A-Si As A Protective Layer, Yhoshua Wug

Student Works

Arguably, the best chance to produce a IR-optical-UV-EUV mirror for a future space observatory is a multilayer mirror coated by a thin bare aluminum layer. Using an Al layer presents challenges that have to be overcome first. Al oxidizes rapidly as soon as it comes in contact with the atmosphere. One solution is to block the oxidation of Al by covering the mirror with a protective layer and remove it once the mirror is in space. freshly, deposited a-Si would be a good candidate for protecting the mirror. Removing it in space also presents some challenges. The best way to …

Observing Kelt Candidate Objects In The Search For Transiting Exoplanets, Maria Martinez

Student Works

The main goal of this project was to learn how to participate and be a part of a real observational team. We worked with the KELT exoplanet search project. While working with the KELT project we hoped to be able to confirm a candidate object as a planet. However, trying to discover a transiting planet was not our main goal for the summer. In addition, we also set out to learn how to work in an observatory, operate telescopes, and process data. The different objects we observed throughout the summer were not all determined to be transiting exoplanets, but we …

Developing Instrumentation For Fabricating And Characterizing Thin Film Aluminum Mirrors, P. Claire Segura

Student Works

The best material for constructing a mirror for a broad-bandwidth telescope that is also capable of reflecting EUV light is pure aluminum. In order to test how the reflectance of aluminum in the EUV range changes as it oxidizes, a system has been constructed that allows a thin aluminum mirror to be constructed inside of a vacuum, where its reflectance can then be tested immediately. Because the experiment must take place in a vacuum, it must also be controlled remotely through a computer program, which manages the mirror fabrication process as well as the collection and analysis of reflectance data. …

Differential Photometry Of High Mass X-Ray Binaries And Be Stars And Determining Standard Stars, Anne Blackwell

Student Works

Building off of the previously established Hα index (Joner & Hintz 2015), I use differential photometry to study high mass x-ray binaries and Be stars using the Hα index to define their level of activity. Specifically I focused of Cygnus X-1 and X Perseus. I took data on Cygnus X-1 (X Perseus will be studied later in the year) to look at its long and short term activity. Data analyzed using differential photometry is merged with previously collected spectroscopic data to show a seamless flow of results between techniques. I also defined the Hα values of 10 stars in the …

Using Advanced Psf Subtraction Techniques On Archival Data Of Herbig Ae/Be Stars To Search For New Candidate Companions, Emily Diane Safsten

Theses and Dissertations

Herbig Ae/Be (HAeBe) stars are intermediate mass (2-10 solar mass) pre-main sequence stars with circumstellar disks. Observing planets within these young disks would greatly aid in understanding planet formation processes and timescales particularly around massive stars. So far, only one planet, HD 100546 b, has been confirmed to orbit a HAeBe star. With over 250 HAeBe stars known, and several observed to have disks with structures thought to be related to planet formation, it seems likely that there are as yet undiscovered planetary companions within the circumstellar disks of some of these young stars. Direct detection of a low-luminosity companion …

Identifying Binary Brown Dwarf Systems Using Model Point Spread Functions, Kyle Matt, Denise Stephens

Journal of Undergraduate Research

The purpose of this project was to improve upon a method for discovering binary brown dwarf systems, and create a program to speed up the implementation of that method. A Brown Dwarf (BD) is a celestial object that is not massive enough to undergo hydrogen fusion in its core, meaning it is too small to be a star, but is also too big to be a planet. BDs can form in low-mass binary pairs. A stellar object located many parsecs away will act as a point source of light for an observer on Earth, therefore the light from such an …

Machine Learning With Scattering Transforms, Jacob Hansen, Gus Hart

Journal of Undergraduate Research

Our goal was to implement scattering transforms as a mathematical representation of materials. The intention of this project was to build intuition on this technique using model data in one and two dimensions. The tools created here will be used as templates in further projects on real materials data. The intuition built during this project is crucial to the machine learning framework for materials design that we hope to build in the near future.

A Photometric Approach To The Redshift Of Galaxies, John Bohman, Joseph Moody

Journal of Undergraduate Research

It is necessary to study the distribution of matter to better understand the universe. There are many difficulties associated with this task however, one of the most basic being that that the universe is an extremely large space, and it takes a lot of time and effort to observe faint objects. Multi fiber spectrometers have made this task much easier, and over 1.4 million spectroscopic redshifts have been obtained. While this is certainly impressive, much remains to be done. This project attempts to develop a survey method capable of detecting and finding the redshift of relatively close (meaning a redshift …

Active Control Of Cylindrical Shells Using The Weighted Sum Of Spatial Gradients (Wssg) Control Metric, Pegah Aslani

Theses and Dissertations

Cylindrical shells are common structures that are often used in industry, such as pipes, ducts, aircraft fuselages, rockets, submarine pressure hulls, electric motors and generators. In many applications it is desired to attenuate the sound radiated from the vibrating structure. There are both active and passive methods to achieve this purpose. However, at low frequencies passive methods are less effective and often an excessive amount of material is needed to achieve acceptable results. There have been a number of works regarding active control methods for this type of structure. In most cases a considerable number of error sensors and secondary …

Determining The Index Of Refraction Of Aluminum Fluoride In The Ultra Violet Spectrum, Zoe Hughes

Student Works

A NASA project called Large UV/Optical/Infrared Surveyor (LUVOIR) is looking into ways to coat a mirror for a new space telescope. We contributed to this project by investigating aluminum fluoride (AlF₃) as a possible coating for the mirror. We measured the index of refraction of AlF₃ in the wavelength range 6 – 49.5 nm by testing three sample mirrors, each made up of a silicon wafer with a coating of AlF₃. We took data at the Advanced Light Source (ALS) in Berkeley, California and in the laboratory at Brigham Young University (BYU). There are discrepancies …

Energy Quantity Estimation In Radiated Acoustic Fields, Eric B. Whiting

Theses and Dissertations

Energy quantities, which are calculated from pressure and particle velocity, yield a great deal of information about acoustic fields. Errors in pressure or particle velocity estimation lead to bias errors the estimation of energy quantities. The bias errors arise from different probe configurations and processing methods. Two processing methods are examined: the traditional method and the recently developed Phase and Amplitude Gradient Estimation (PAGE) method. These two methods are compared to investigate how each estimates pressure and particle velocity and the subsequent bias errors in a plane wave, standing wave, and spherical spreading wave field. Analytical expressions are derived for …

Increasing The Computational Efficiency Of Combinatoric Searches, Wiley Spencer Morgan

Theses and Dissertations

A new algorithm for the enumeration of derivative superstructures of a crystal is presented. The algorithm will help increase the efficiency of computational material design methods such as cluster expansion by increasing the size and diversity of the types of systems that can be modeled. Modeling potential alloys requires the exploration of all possible configurations of atoms. Additionally, modeling the thermal properties of materials requires knowledge of the possible ways of displacing the atoms. One solution to finding all symmetrically unique configurations and displacements is to generate the complete list of possible configurations and remove those that are symmetrically equivalent. …

Performance Of Phase And Amplitude Gradient Estimator Method For Calculating Energy Quantities In A Plane-Wave Tube Environment, Daxton A. Hawks

Student Works

Acoustic intensity, energy densities, and impedance are useful quantities when considering sound fields. Calculating these energy quantities relies on measurements of acoustic pressure and particle velocity. Pressure and particle velocity can be directly measured, but direct measurements of particle velocity are difficult to make, and are normally inaccurate. A more common and effective way to find particle velocity is to estimate it using pressure measurements from two closely-spaced microphones. The traditional way of estimating particle velocity is severely limited by frequency. The PAGE method, developed at Brigham Young University, extends the frequency bandwidth at which accurate estimations can be made. …

Daxton Hawks Reu Prospectus, Daxton A. Hawks

Student Works

The purpose of my research is to investigate the ability of the PAGE method to improve the frequency bandwidth of calculations of energy-based quantities from multiple pressure microphones. I will accomplish this by investigating sound waves in both plane-wave and standing-wave environments. I will compare the PAGE method calculations for Ia, Ir, Ep, Ek, and Z to those of traditional and analytical expressions, based on careful ambient condition monitoring. Quantifying the bandwidth extension of the PAGE method for these energy-based quantities will lay a foundation for further application.

Preventing Oxidation Of Aluminum Films With Cadmium Of Zinc Barriers, Spencer B. Perry

Student Works

The planned Large UV/Optical/Near-infrared Telescope (LUVOIR) is expected to launch sometime in the 2030s if NASA surveys recommend LUVOIR over several other projects in early developmental stages [1]. As the project title suggests, the proposed telescope would include large mirrors (between 8 and 16 meters) as part of the orbiting reflector telescope. My research focused on the preparation of aluminum mirrors with zinc or cadmium barrier layers that were designed to prevent oxidation of the aluminum.