Bulletin of the American Physical Society
10th Annual Meeting of the Northwest Section of APS
Volume 53, Number 6
Thursday–Saturday, May 15–17, 2008; Portland, Oregon
Session G3: Industrial/Applied Physics |
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Chair: Brian Milbrath, Pacific Northwest National Laboratory Room: Olin 204 |
Saturday, May 17, 2008 2:00PM - 2:36PM |
G3.00001: Measuring Stream Dynamics with Fiber Optics Invited Speaker: I'll review recent work using a fiber optic based distributed temperature system to gauge stream temperatures over a several kilometer reach with spatial resolution down to one meter, and temperature resolution to 0.1C. The system has been installed in the H. J. Andrews Long Term Ecological Research Site in southern Oregon to help gauge ground water/surface water fluxes, as well as the Walla Walla river to aid with fish habitat studies. The talk will describe how interdisciplinary work between applied physics and ecology can provide novel measurement solutions for ecologies and climates in flux. [Preview Abstract] |
Saturday, May 17, 2008 2:36PM - 3:00PM |
G3.00002: Ultrasonic measurements of thin zinc layers on concrete Henri Jansen, Bill Brooks, Vinh Nguyen, Milo Koretsky In order to protect bridges at the coast from corrosion, a thin layer (approximately 0.5 mm) of zinc is sprayed on the concrete of the bridge. When this zinc layer is electrically connected to the reinforcing steel (rebar) and placed at a positive potential with respect to the rebar, oxidation is favored at the zinc layer and reduced at the rebar. The resulting protection of the rebar fails when the zinc layer delaminates from the concrete or when the zinc oxidation product layer becomes too thick. We have used ultrasonic detection to investigate the properties of the zinc layer. This method has been applied very successfully in the semiconductor industry. We present the details of the method and the expected response. Unfortunately, we are not able to measure changes in the zinc layer, because either the frequency we use (10-20 MHz) is too low, or scattering in the concrete is a dominant effect. [Preview Abstract] |
Saturday, May 17, 2008 3:00PM - 3:24PM |
G3.00003: A Stochastic Semiclassical Time Front Prediction for Ocean Acoustics Katherine Hegewisch, Steven Tomsovic Low frequency sound propagates in the ocean within a wave guide formed by the confining effects of temperature, salinity and pressure on the sound speed. This wave guide enables long range propagation upwards of 3000 km. Within the wave guide, sound scatters due to range dependent sound speed oscillations from internal waves and gives rise to wave chaos, where most of the classical rays are chaotic. This chaos poses challenges to ray predictions of the range and frequency dependence of properties of the 'time fronts', the acoustic arrivals in depth and time. Though semiclassical theory works well for strongly chaotic systemss, finding the necessary eigenrays for long ranges is unrealistic here. Instead, we utilize semiclassical and perturbation theories ONLY for short ranges and extend these results to long ranges using a previously introduced diffusive theory. We verify the diffusive assumptions and demonstrate the analytic results for these theories for short ranges before arriving at a stochastic prediction. [Preview Abstract] |
Saturday, May 17, 2008 3:24PM - 3:38PM |
G3.00004: BREAK
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Saturday, May 17, 2008 3:38PM - 4:02PM |
G3.00005: Minimal energy damping in an axisymmetric flow Alexander Sachs The method of Lagrange's undetermined multipliers is used to find the velocity field which minimizes the energy damping for a viscous incompressible fluid described by the Navier- Stoke equation. The vorticity of this velocity field obeys a Helmholtz equation with an undetermined parameter. This Helmholtz equation is used to determine the axisymmetric velocity field in a cylinder. This velocity field is slightly different from the Poiseuille velocity field. The rate of energy damping per unit energy is calculated as a function of the parameter. It is a minimum when the parameter is equal to the root of a Bessel function. [Preview Abstract] |
Saturday, May 17, 2008 4:02PM - 4:26PM |
G3.00006: Physics and the Lung Richard Jacob, Kevin Minard Lungs are complex, dynamic organs whose primary purpose is gas exchange. Various physics principles are critical to understanding lung function, and an application of physics can help elucidate how different diseases affect the lungs' ability to move air and exchange gas. Recent advances in gas-phase magnetic resonance imaging (MRI) allow for gas dynamics to be quantified non-invasively. Gas flow velocity in the major airways and diffusion (Brownian motion) in the deep lung can be quantified in vivo in three dimensions with MRI. Application of these techniques may facilitate improved disease diagnosis and patient-specific therapeutic interventions. In this presentation a brief overview of basic lung physics will be given and our recent use of in vivo hyperpolarized 3-He MRI for visualizing gas transport in healthy and diseased rat lungs will be summarized. [Preview Abstract] |
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