Bulletin of the American Physical Society
86th Annual Meeting of the APS Southeastern Section
Volume 64, Number 19
Thursday–Saturday, November 7–9, 2019; Wrightsville Beach, North Carolina
Session J02: Applied Physics |
Hide Abstracts |
Chair: Mohammad Ahmed, North Carolina Central University Room: Holiday Inn Resort Airlie/Tidewater |
Saturday, November 9, 2019 10:30AM - 10:42AM |
J02.00001: Elucidation of fatigue fracture behavior by using ESPI Naoya Fujishima, Sanichiro Yoshida, Tomohiro Sasaki The goal of this research is to elucidate the fatigue fracture mechanism via analysis of dynamic behaviors of displacement field. We use an optical interferometric technique known as Electronic Speckle-Pattern Interferometry (ESPI) to observe the temporal behavior of the displacement pattern in metal specimens under fatigue loading. Our hypothesis is that fatigue fracture is preceded by shear instability and the displacement data obtained with ESPI exhibits critical features that indicate shear instability. Our theoretical investigation indicates that shear instability is related to dislocation dynamics and it can be observed by unstable temporal behavior of the displacement field. [Preview Abstract] |
Saturday, November 9, 2019 10:42AM - 10:54AM |
J02.00002: Dynamic deformation analysis by Electronic Speckle Pattern Interferometry Shun Takahashi, Sanichiro Yoshida, Tomohiro Sasaki The aim of this study is to develop a dynamic analysis method for in-plane displacement measurement with Electronic Speckle Pattern Interferometry (ESPI). ESPI is an optical method that uses the interference of speckle patterns formed on material surfaces by laser. Our ESPI technique forms speckle patterns (interferogram) with two lasers applied to the specimen surface at two different incident angles so that in-plane displacements of points on the surface cause relative phase change between the two optical paths. We keep taking interferograms at a constant time interval and subtract electronically the interferogram formed at a time step from another. So-called interference fringe patterns are formed from each pair of interferogram where dark fringes represent contours of displacement proportional to the laser's wavelength. For quantitative analysis we need to locate dark fringes on the fringe pattern, express them using the coordinates variables, and evaluate the relative phase change on all coordinate points. This task is complicated because the orientations and locations of dark fringes are random. In this study, we apply techniques widely used in neural network algorithms to locate dark fringes and evaluate relative phase changes automatically. [Preview Abstract] |
Saturday, November 9, 2019 10:54AM - 11:06AM |
J02.00003: Retrospective dosimetry in radiological emergency response, epidemiology and nuclear nonproliferation. Ryan O'Mara, Fatma Abdelrahman, Egemen Aras, Aleem Tareen The RDNA group at NC State has demonstrated how ubiquitous items such as ceramics, foodstuffs and effectively every insulator material found in society can serve as a radiation dosimeter to some extent. The techniques utilized include thermoluminescence, optically stimulated luminescence and electron paramagnetic resonance spectrometry. Using these to measure dose depth profiles into properly prepared materials, incident radiation fields can be reconstructed with low resolution equivalency. Sampling over a grid has been shown to enable spatial source reconstruction utilizing inverse square dependencies. Items found commonly on a person such as confectionary or simple electronics have been shown to serve as excellent dosimeters approaching natural background levels when integrated over many years. It is finally shown how these can serve in reconstructing emergency triage doses in any large scale population exposure. Likewise dose reconstruction for epidemiology and even in nuclear nonproliferation from a forensics perspective have been demonstrated as viable applications. [Preview Abstract] |
Saturday, November 9, 2019 11:06AM - 11:18AM |
J02.00004: Kink-Resistant Electrospun Vascular Grafts with Additive Manufacturing Reinforcement Kiran Adhikari, Jordan Zimmerman, Vinoy Thomas Failure in the implanted small caliber vascular grafts is caused by the mechanical mismatch between the native vessels and the implanted graft. Mechanical issues persist with longer, smaller-diameter vascular grafts, which are needed to treat peripheral arterial diseases(PADs) or replace vessels such as the small saphenous vein, since mimicking native vessels' properties and eliminating kinks and loops in longer grafts has seen little success. Electrospinning and 3D printing are two fabrication techniques that have recently garnered considerable attention and were used in conjunction during this project to maximize their respective benefits for longer, smaller-diameter vascular grafts. Marrying these technique to improve the mechanical properties, we report improved apparent elastic moduli, most notably in the radial direction, as well as substantial reduction of kink radii. SEM images shows the mesh structure in the nanoscale which mimics the ECM of native blood vessels. [Preview Abstract] |
Saturday, November 9, 2019 11:18AM - 11:30AM |
J02.00005: Flocking Transition in a Self-propelled Particle Model Using Experimental Motility Conditions Jelani Lyles, Paul Yanka, Daniel Sussman, Lisa Manning, Chih Kuan Tung Flocking transition has been studied using self-propelled particle models for decades. In these models, the initial angular distribution is random, the step-by-step angular fluctuation is either a bounded flat noise or a Gaussian noise, and the magnitude of the velocity of each moving particle is thought to be a constant. Experimental study of sperm flocking show that an aligned initial condition promotes sperm to form large flocks, angular fluctuation follows an exponential decay, and the velocity distribution follows a Gamma distribution. Our research has focused on using a computational model to understand the effects from those differences between experimental observation and the traditional model conditions. We found that aligned initial condition does help sperm to form larger flocks when the system is at the transition, but not much effect elsewhere. No major difference was seen between exponential and Gaussian angular noise. The Gamma velocity distribution was found to lower the density of the flocks. Our results provide evidence to rethink adapting the conclusion from active matter models to experimental systems. [Preview Abstract] |
Saturday, November 9, 2019 11:30AM - 11:42AM |
J02.00006: An Optically-Locked Interferometer for Attosecond Pump Probe Setups John Vaughan, Joseph Bahder, Brady Unzicker, Davis Arthur, Morgan Tatum, Trevor Hart, Geoffrey Harrison, Spenser Burrows, Patrick Stringer, Guillaume Laurent Ultrafast pump-probe measurements at the attosecond time scale are generally achieved by exposing the target to both an attosecond pump pulse and a phase-locked IR probe field, with a variable time delay between the two. To fully exploit the temporal resolution of attosecond pulses for time-resolved studies, the time delay between the pump and probe pulses must be controlled with attosecond resolution as well. This requires the ability to linearly vary the delay with time steps of the order of the pulse duration (or less), and maintain it to any desired value over extended periods of time. We present the design and performance of an active stabilization system for attosecond pump-probe setups based on a Mach-Zehnder interferometer configuration. The system employs a CW laser propagating coaxially with the pump and probe beams in the interferometer. The stabilization is achieved with a standalone feedback controller that adjusts the length of one of its arms to maintain a constant relative phase between the CW beams. With this system, the time delay between the pump and probe beams is stabilized within 10 as rms over several hours. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700