Bulletin of the American Physical Society
Annual Meeting of the APS Four Corners Section
Volume 62, Number 17
Friday–Saturday, October 20–21, 2017; Fort Collins, CO
Session E7: General Physics I |
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Chair: Mark Coffey, Colorado School of Mines Room: Lory Student Center 304 |
Friday, October 20, 2017 1:20PM - 1:44PM |
E7.00001: Doing Research with Undergraduates in a Bachelor's-only Physics and Astronomy Department: Challenges and Successes Invited Speaker: Matthew Semak For many disciplines, it appears that the number of undergraduates involved in research is increasing. One can certainly argue that this is true for physics and astronomy. This is encouraging given the range of benefits students gain from such an experience. At UNC, we have been fortunate to have undergraduate research as a component of the program for over 30 years. However, many students are overcome by classwork and do not see research as a viable option during their undergraduate career. Indeed, some are weary of approaching such a challenge given their limited experience with such a process. Moreover, without the extensive research efforts, facilities, graduate student mentors, and other important resources associated with graduate institutions, can an undergraduate program provide a meaningful research experience for its students? Indeed, the lack of funding devoted to student projects and the often-limited external collaborations can have students wondering about opportunities of which they were not aware. They also ask if they have been given the full range of tools for current and future success. These are frequent questions. I would like to discuss some possible answers by telling you about some of the journeys in research my colleagues and I have taken with our undergraduates. With persistent attention to the evolving needs of our students along with an understanding of our advantages and limitations, I believe our program has substantial positive outcomes to report. [Preview Abstract] |
Friday, October 20, 2017 1:44PM - 1:56PM |
E7.00002: Physics in Industry, a Personal Perspective Benjamin Pratt-Ferguson Often, Physicists enter the industrial workforce without much exposure or information on what to expect. Yes, they know how to solve problems and accomplish research into detailed subject areas, but what should they expect when joining a company where Engineering discipline is paramount? This talk will discuss the requirements placed on new employees at an engineering based company, and the role of the physicist in the organization, along with statistical background information on physics in industry. [Preview Abstract] |
Friday, October 20, 2017 1:56PM - 2:08PM |
E7.00003: Classification of sloppy models based on curvature Benjamin Francis, Mark Transtrum Often in physics, complex processes can be explained by relatively simple models. A explanation for the existence of these effective theories, known as sloppiness, has recently been proposed using Information Geometry. In this approach, models are mappings between parameters and predictions that are naturally interpreted as manifolds. Sloppy models are characterized by a low effective dimensionality, that is, the manifold is bounded with many very narrow widths. Narrow widths correspond to irrelevant directions while long directions correspond to the relevant directions of the effective theory. We consider the curvature of several model manifolds. In many cases, the curvatures are small compared to the manifold widths. In other cases, such as oscillatory systems, the curvatures are much larger. Large curvatures pose technical challenges for model analysis, e.g., leading to local minima in the objective function when fitting to data. However, they can also be the signature of high dimensionality in the effective theory, for example, as in chaotic systems. We propose a subclassification of sloppy models based on their curvatures and discuss its broader implications for modeling complex systems. [Preview Abstract] |
Friday, October 20, 2017 2:08PM - 2:20PM |
E7.00004: Wind-turbine lightning protection: Electrostatic models are not sufficient Richard Sonnenfeld, Sidharth Arunkumar, Ashok Ghosh Wind turbines made of non-conducting composites currently use
lightning receptors to reduce damage.
Attempts to understand receptor effectiveness
have focused on electrostatic models of $\vec{E}$-field around the
turbine in the presence of an incoming lightning leader.
We created such an electrostatic model using COMSOL,
to test the hypothesis in the wind community
that a receptor with a larger static field at this ``striking distance''
is a more effective lightning interceptor.
While we modeled field for a real turbine, we could not do a
lab test of same. Instead, a circuit board (PCB)
with copper stripes (cathodes) of varied spacing (s) was fabricated.
($1.1 \; cm |
Friday, October 20, 2017 2:20PM - 2:32PM |
E7.00005: Qualitative analysis of mode transitions in bottle-shaped resonators with waterfall plots Bonnie Andersen, Josh Dimond, Cicely Potter, Aaron Horikami A closed bottle-shaped resonator consists of a coupled acoustic system with the neck behaving as a quarter-wave resonator and the cavity as a half-wave resonator. Such a system gives rise to overtones that are not harmonic of the fundamental and could be used as a thermal sensor. A thermoacoustic stack subject to a temperature gradient can generate self-sustained oscillations within the bottle. Mode transitions were previously observed to occur at the same position within a few millimeters when a piston controlled with a translation stage was moved up or down with a manual control to adjust the cavity length. The dominant mode was recorded using a power spectrum of the signal measured with a pressure sensor. In this study, the piston motion is automated and eight neck/cavity combinations were tested at three different piston speeds and at various input powers. The input powers were adjusted to just above thermoacoustic onset and not to exceed thermal limits of the materials used. Waterfall plots allow the visualization of the time evolution of the power spectrum where intensity is plotted both as a function of time and frequency. Qualitatively, the transitions occur at the same place within the cavity after a threshold input power is reached. [Preview Abstract] |
Friday, October 20, 2017 2:32PM - 2:44PM |
E7.00006: Time Resolved Quantum Field Theory Tyler Kharazi Recent work by Glasgow, Smith, Ware, et al gave a non-perturbative approach in time-resolved quantum field theory, and showed their methods in the Hamiltonian of Quantum Electrodynamics. Their work, however, only considered a subspace of QED where only one electron and one photon were considered, causing the Coulomb potential to become trivial. In this presentation we will extend the results of the previous authors to consider a field theory including electrons, positrons, and photons, causing the Coulomb term to play a role in the dynamics of the system. We show that analysis of the Coulomb term is non-trivial and forces us to consider a new method in projecting down onto 1$+$1D subspace of the full field theory. [Preview Abstract] |
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