Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session C37: Undergraduate Research VI: Education Research and Related StudiesEducation Live Undergrad Friendly
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Sponsoring Units: APS/SPS Chair: Olga Shishkov, University of Colorado, Boulder |
Monday, March 15, 2021 3:00PM - 3:12PM Live |
C37.00001: Exploring the Intensity versus Distance Profile of Light Emitted by a Household UV Bulb Sairam Tangirala, Ashkar Ibne Awal, Tae Song Lee We studied the intensity versus source-to-sensor distance profile of the UV radiation emitted by a household UV bulb. Quite often, in an introductory college physics laboratory, there is no laboratory equipment capable of detecting and measuring UV radiations. We built a custom experiment set up using a GUVA-S12SD sensor and found that the UV intensity (y) decreases as the source-to-sensor distance (x) increases in accordance to the power law, . Our experimentally determined power-law exponent deviated from the theoretical inverse-square exponent of -2.0. We systematically explored the role of UV bulb’s geometry and its enclosure, in explaining the deviation from the inverse-square law behavior. We also present a theoretical model that confirms our experimental findings of the power law exponent. |
Monday, March 15, 2021 3:12PM - 3:24PM Live |
C37.00002: Exploration of the Q Factor of a Parallel RLC Circuit Jack Paulson, Michael Ray RLC circuits are used for many applications in science and electronics. The Q factor is used to determine how much an oscillating system is damped; for a series RLC circuit Q is inversely proportional to the resistance but is found to be proportional to the resistance in a parallel RLC circuit. Here we explore this counterintuitive result and attempt to draw an analogy from the parallel RLC circuit to a damped-driven harmonic oscillator. |
Monday, March 15, 2021 3:24PM - 3:36PM Live |
C37.00003: Evading instabilities in spring-mass chains with time-modulated stiffnesses Noah Kruss, Jayson Paulose The vibrations of a one-dimensional elastic continuum or a string under tension are classic examples of harmonic analysis, with normal modes taking the form of standing waves which are sinusoidal in space and time. Less widely known are the modes of systems in which the global stiffness or tension is sinusoidally varied in time. In such systems, standing waves still exist, but their temporal evolution is described by Mathieu functions which become unstable at certain wavelengths. We investigate the vibrations of a periodic spring-mass chain with time-modulated spring stiffnesses, using classical dynamics simulations implemented in HOOMD-Blue software. Upon initializing the system in standing waves of different wavelengths and tracking the subsequent evolution, we obtain quantitative agreement of trajectories with predicted Mathieu functions. By analyzing the relationships between system properties and stability of standing waves, we find parameter combinations for which the discrete system has no unstable modes, in contrast to the continuum equivalents which generically harbor instabilities. Our results show that discrete time-modulated systems can be dynamically stable without requiring losses or damping. |
Monday, March 15, 2021 3:36PM - 3:48PM Live |
C37.00004: Incorporating active flow control in future wing designs for ultra-high bypass ratio engine integration. Jack Proudfoot, Mark Jabbal The introduction of ultra-high bypass ratio engines creates a significant challenge to wing-designers. The increased nacelle size necessitates a cut-out in leading-edge slats, this induces separated flow at take-off and landing resulting in a loss of lift and increased drag. Active flow control (AFC) is a proven technique to suppress turbulent boundary layer separation and the use of pulsed jet actuators (PJA) is of interest thanks to the lower energy requirements when compared to steady blown or suction techniques. However, very little work has been done to prove this technology is viable for commercial use. The purpose of this study was to experimentally compare different AFC strategies such as momentum redistribution and momentum injection through variations in PJA layouts. The goal was to recover lost CL_max due to the slat cut-out (~6%), the optimum configuration of PJA was found by comparing the required energy input. This was demonstrated by conducting large scale wind tunnel tests, using oil flow technique to visualize surface skin friction lines and force balance measurements at representative Reynolds numbers for take-off conditions on a representative future-wing design. |
Monday, March 15, 2021 3:48PM - 4:00PM Live |
C37.00005: How External Boundaries Affect the Number of Bound States in a Quantum Well Sarah Babione, Todd Timberlake This study examines the number of bound (negative energy) states in one-dimensional quantum wells of width w confined within an infinite square well (ISW) of width W. Six different quantum wells were explored: a finite square well and one to five delta wells inside the ISW. These systems admit zero-energy states with piecewise linear eigenfunctions for certain combinations of the ratio r = W/w and the strength (α) of the delta wells or depth (V0) of the finite square well. Using these zero-energy conditions, we can determine how the number of negative-energy states changes when the ratio r is changed. We determine the zero-energy conditions for each case analytically. The zero-energy curves divide the parameter space (α/V0 vs. r) into regions with different numbers of negative energy states. Passing over a zero-energy curve changes the number of negative energy states by one. For the systems with the finite square well, the single delta well, and the two delta wells inside the ISW, the number of bound states changes by at most one when changing r alone. For the systems containing three, four, or five delta wells inside the ISW, the number of bound states changes by at most two when changing r alone. |
Monday, March 15, 2021 4:00PM - 4:12PM Live |
C37.00006: Reconstructing Charge Density Wave State Domains in 1T-TaS2 James Huber, Manoj k Singh, Boning Yu, Bishnu Sharma, Michael Boyer Low-dimensional conducting materials host a wealth of interesting physics. When a low-dimensional material enters a charge density wave (CDW) state, that material undergoes a periodic electronic and structural transformation. Scanning tunneling microscopy (STM) measurements can detail, at the atomic scale, the electronic and structural properties of CDW states. By first analyzing Fourier transforms of STM topographies acquired on the 1T-TaS2 CDW compound, we extract essential wavevectors to allow us to computationally recreate STM topographic features so as to understand the nature of the material’s nearly-commensurate CDW state. |
Monday, March 15, 2021 4:12PM - 4:24PM Live |
C37.00007: Editing an Open Access Text to Increase the Accessibility of General Undergraduate Education in Physical Science Zachary Zintak, Nadine Gergel-Hackett The purpose of this project is to combine two preexisting open access textbooks, one physics and one chemistry, into a single abridged open access text for an introductory physics/chemistry course at Mary Baldwin University, as well as for use by the general public. This work was performed as part of a VIVA Course Redesign Grant to increase the accessibility of physical science to students and educators everywhere. Because many students at MBU are non-science majors, this text provides them the opportunity to gain a general understanding of these physical sciences. As the undergraduate researcher, I assisted in making this text approachable to those taking this introductory class by adding figures and links that provide additional information to the reader to better understand the material. I also edited the text for general understanding, providing insight via the perspective of an undergraduate student. |
Monday, March 15, 2021 4:24PM - 4:36PM Live |
C37.00008: Educational Approach to Active Circuits for Vacuum Tube Langmuir Probes Philip Andrango Asynchronous learning has produced challenges to developing technical work of physics students. Building circuits from modules that can be utilized in remote learning is a method for which educators have mandated students to purchase. This paper utilizes a similar notion of creating modules with limiting the components to differential amplifiers, inverting amplifiers, and push-pull circuits. Specifically making components from LM741 operational amplifier or general purpose components engages students with replaceable components to create active circuits for a distributable experiment. Vacuum tubes utilize the same physical principles as Langmuir probes and are ideal for compact plasma experiments in conjunction with the active circuit modules. Developing active probe circuits is a method for which the technical aspect of physics research can be taught in an asynchronous learning environment. |
Monday, March 15, 2021 4:36PM - 4:48PM Live |
C37.00009: Two-dimensional Surfaces as Analogs for Potential Energy Functions Robert Mbenoun Mahend, Todd Timberlake
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Monday, March 15, 2021 4:48PM - 5:00PM Live |
C37.00010: Characterizing Time-Frequency Localization for Electronic-Wavefunction Basis Sets Antonino Travia, David Rabson The Dirac basis for discretely sampled data is completely localized in |
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