Bulletin of the American Physical Society
79th Annual Meeting of the APS Southeastern Section
Volume 57, Number 16
Wednesday–Saturday, November 14–17, 2012; Tallahassee, Florida
Session DA: Applied Physics I |
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Chair: Richard Haglund, Vanderbilt University Room: DoubleTree Ballroom |
Thursday, November 15, 2012 1:30PM - 2:00PM |
DA.00001: Electrical Disturbances in Near-Earth Orbits due to Space Plasmas Invited Speaker: William Atkinson A Simulator is presented that models the disturbance of electrical circuits by high energy electrons trapped in earth's radiation belts; the model components are a module computing the electron fluence rate given the altitude, the time of the year, and the sunspot number, a module that models the interaction of the electrons with the materials of the electrical component, and a module that computes the charge and the magnitude of electrical field in the insulating materials as a function of time. The Adameic-Calderwood equation is used to model the relationship between the electrical conductivity of dielectric materials and the electric field intensity, making the charging/discharging equations highly non-linear. The non-linearity of the charging equations becomes especially pronounced in magnetic storms during intense solar flares. The results show that the electric field intensity can approach the dielectric breakdown strength in materials commonly used as dielectrics in space-based systems and that the fields can be sustained at high levels for as long as an hour. [Preview Abstract] |
Thursday, November 15, 2012 2:00PM - 2:30PM |
DA.00002: Transdisciplinary Research Opportunities at the Western Kentucky University Nondestructive Analysis Center Invited Speaker: Edward Kintzel The Western Kentucky University (WKU) Nondestructive Analysis (NOVA) Center has been established within the Commonwealth of Kentucky. The acquisition of the Large Chamber-Scanning Electron Microscope (LC-SEM) has positioned WKU as the only university in North America with an instrument of this type. As envisioned, the NOVA Center will be a national focal point for nondestructive measurements. The reach of this Center is toprovide analytical services, by being the only educational institution within North America to offer non-destructive SEM analysis. Transdisciplinary studies will be presented that highlight the extensive suite of materials characterization techniques available at the WKU NOVA Center. [Preview Abstract] |
Thursday, November 15, 2012 2:30PM - 2:42PM |
DA.00003: Development of an In-Situ Load Frame in a Large Chamber Scanning Electron Microscope Jason Leszczewicz, Edward Kintzel, Robin Woracek, Dayakar Penumadu, Stephen Young A high capacity custom designed uniaxial (tension-compression) mechanical testing system has been developed and integrated in to a 1.5 meter Large Chamber Scanning Electron Microscope (LC-SEM). This testing system provides unique ability to apply large axial force (up to 90 kN) for imaging deforming materials using various imaging modalities possible with electrons (secondary, back-scattered, and diffracted) using a close-loop control interface using National Instruments hardware and software. A wide spectrum of specimen sizes and materials can be accommodated and there is no limitation to using small sized specimen, as usually required in traditional SEM based tensile stages offered through vendors such as Gatan. This system is integrated for user access at the recently established Nondestructive Analysis Center (NOVA) at Western Kentucky University (WKU) that offers LC-SEM for advanced material analysis. The LC-SEM is also equipped with Focused Ion Beam (FIB), Energy Dispersive X-ray Spectrometry (EDS), Fourier Transform-Infrared (FT-IR) Spectroscopy and can operate under variable pressure mode. Initial results will be presented in this paper for metallic and polymeric composite materials using secondary electron based images. [Preview Abstract] |
Thursday, November 15, 2012 2:42PM - 2:54PM |
DA.00004: Investigation of nanofibers in the interfacial transition zone of concrete Jahi Palmer, Shane Palmquist, Linda Cruz, Keith Andrew, Edward Kintzel Mechanical properties of concrete are most commonly determined using destructive tests including: compression, flexure, and fracture notch specimen tests. However, nondestructive tests exist for evaluating the properties of concrete such as ultrasonic pulse velocity and impact echo tests. One of major issues with concrete is that unlike steel it is quasi-brittle material. It tends to want to crack when tensile stresses develop. These cracks generally develop at the interfacial transition zone (ITZ) between the cement paste and the aggregate. Fibers have been added to concrete for many years to help with temperature and shrinkage cracks. In more recent years, the concepts of adding fibers with enhanced properties such as carbon and glassy nanofibers (NFs), to concrete have been explored. Some possibilities include developing concrete that may be more durable, flexible, stronger, less permeable, and potentially ``crack free'' than traditional concrete. Based on SEM images and quantitative data taken using the Large Chamber Scanning Electron Microscope at Western Kentucky University, this study examines the ITZ of concrete made with NFs. Results provide greater understanding on the nature of the ITZ region in concrete made with NFs. [Preview Abstract] |
Thursday, November 15, 2012 2:54PM - 3:06PM |
DA.00005: Shock Formation and Disintegration in Fluids with Non-Convex Equations of State Fatemeh Bahmani, Mark Cramer We consider the steady, two-dimensional, inviscid, high-speed, flow around thin turbine blade profiles with special attention given to fluids having a non-convex equation of state; such fluids are commonly known as Bethe-Zel'dovich-Thompson (BZT) fluids. We show that the essential flow physics can be described by an inviscid Burgers equation having quartic nonlinearity rather than the quadratic nonlinearity of perfect gases. In order to illustrate the flow behavior, a fifth-order WENO (weighted essentially non-oscillatory) numerical scheme is employed. New results of interest include the formation of oblique expansion shocks, shock-splitting induced by the interaction of a single shock with Mach waves, the capture of shock-fan combinations, and the collision of oblique compression and expansion shocks. [Preview Abstract] |
Thursday, November 15, 2012 3:06PM - 3:18PM |
DA.00006: Evolution of Turbulence in High Temperature Plasmas James B. Titus, Alonzo B. Alexander, Ephrem Mezonlin, Abdulgader Almagri Turbulence measurements have been made in high temperature plasma in the Madison Symmetric Torus (MST) at the University of Wisconsin--Madison. Techniques from Fourier analysis and chaos theory are used to characterize magnetic turbulence in different plasma regimes, including magnetic reconnection and increased confinement. The Fourier components measure: the driving wavenumbers associated with instabilities, the amount of energy in different scales, and the rate at which that energy moves between scales. The chaos components measure the complexity of the fluctuations. More specifically, the Beta model for intermittency in 3D turbulence suggests that the fractal dimension, needed to account for non-space filling, can modify Kolmogorov's 5/3 Law. The correlation dimension is used to estimate the fractal dimension during the evolution of different plasma events. During magnetic reconnection, it has been seen that as the magnetic energy decreases during a sawtooth crash, the energy in the ion-cyclotron frequency range (or dissipation region) increases and the fractal dimension sharply peaks. This suggests that complexity may play a role during the redistribution of energy through turbulence. These techniques will be the stepping-stones for turbulence studies at the Spheromak Turbulent Physics Experiment (STPX) at Florida A\&M University. [Preview Abstract] |
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