Bulletin of the American Physical Society
Annual Meeting of the Four Corners Section of the APS
Volume 59, Number 11
Friday–Saturday, October 17–18, 2014; Orem, Utah
Session D4: General Physics I |
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Chair: Raymond T Perkins, Utah Valley University Room: Science Building 073 |
Friday, October 17, 2014 1:50PM - 2:14PM |
D4.00001: Increased Water Surface Skipping through Extreme Elasticity Invited Speaker: Tadd Truscott Many of us are familiar with the pastime of stone skipping. Parameters such as stone shape, incident angle with water surface, and angular velocity are critical parameters for gyroscopic stabilization and successful skips. Once the ideal, smooth, disk-like stone is located it is important to cast the stone with appropriate angle to the water surface, the correct amount of tilt and sufficient angular velocity to provide gyroscopic stabilization. If done correctly, the stone will skip several times across the surface of the water. In contrast, the Water Bouncing Ball (Waboba) can be skipped significantly more times with little effort to the details of throwing mechanics. This is primarily due to the extreme elasticity of the material from which the Waboba is made. We present the skipping dynamics of highly deformable elastic spheres. Impact angle, velocity, diameter and shear modulus are experimentally varied and the resulting impact phenomenon investigated using high-speed photography and image processing techniques. The data show that sphere impact initiates a material wave within the projectile sphere, dependent on the impact conditions. The relative time scales associated with these material waves and the contact time of the sphere with the water predict the efficiency of the skipping event. We present a theoretical model for the impact event with associated scaling laws. Additionally, we present how impact dynamics change with each successive skip, digressing from high-energy material modes to lower energy modes. [Preview Abstract] |
Friday, October 17, 2014 2:14PM - 2:26PM |
D4.00002: Geophysical Survey of Gossans in the Eastern Uinta Mountains, Utah Daniel Natter, David Sutterfield, Ephram Matheson, Andrew Fletcher, Michael Arnoff, Andrew Lawrence, Steven Emerman, Steven Fellows When sulfide-bearing rocks are exposed to oxidizing conditions, they become destabilized, leaving behind a framework of leached, altered, and replaced host rock called a gossan. Many of these gossans form by the oxidation of ore minerals and are associated with ore deposits. There have been no previous published studies of gossans in Utah either in terms of their economic potential or geophysical signature. The objective of this study was to determine the geophysical signature of gossans exposed on the eastern margin of the Uinta Mountains in Utah. The gossans overlie a wedge of Mississippian Madison Limestone and are bounded by the South Flank Fault, which forms the boundary between the Permian Weber Sandstone to the south and the Neoproterozoic Uinta Mountain Group metaquartzites to the north. The geophysical surveys included electrical resistivity, induced polarization (IP), self-potential, total magnetic field, and magnetic susceptibility of exposed rocks. Inversion of the resistivity and IP measurements shows both a resistivity low (200 $\Omega \cdot $m) and a chargeability high (7 ms) below a depth of 23 m. Magnetic anomalies of amplitude 100 nT and wavelength 50 m are consistent with magnetic models that include isolated bodies of elevated magnetic susceptibility (0.08 SI units) with upper surfaces 20-30 m below the surface. Since the depth to the water table is also 20-30 m, the geophysical measurements are consistent with reduced sulfide bodies below a depth of 20-30 m. [Preview Abstract] |
Friday, October 17, 2014 2:26PM - 2:38PM |
D4.00003: Towards a New Classification of Rivers based upon Generic Stage-Discharge Rating Curves Benjamin Parsons, Jeremiah Rundall, Michael Jorgensen, Steven Emerman The practice in hydrology is to deduce stream discharge from stream stage by creating a rating curve for each stream site from simultaneous measurements of stage and discharge. If a river could be assigned a generic rating curve with a small number of parameters, the cost of developing rating curves could be reduced. The first step has been to classify rivers according to whether there is a unique relationship between stage and discharge. The USGS National Water Information System database of about 3.8 million simultaneous measurements of stage and discharge at 15,345 active and historic stream gaging sites was imported into a Python-driven data manipulation script. Linear relationships between z-scores of the logarithms of stage and discharge were developed for each site. A frequency spectrum of the slopes of the linear relationships was created by summing the normal distributions for each site with mean equal to slope and standard deviation equal to uncertainty in slope. There were no stream gaging sites at which discharge changed without a change in stage. At about 70{\%} of stream gaging sites, over 90{\%} of the variation in stage corresponded to a variation in discharge. At the remaining sites, significant variation in stage occurred without a variation in discharge. Current research involves identifying the characteristics of stream sites that lack a unique stage-discharge relationship and creating classes of generic rating curves by considering more complex functional fits. [Preview Abstract] |
Friday, October 17, 2014 2:38PM - 2:50PM |
D4.00004: Magnetic Susceptibility of Tree Leaves as a Simple, Cost-Effective Means of Monitoring Air Quality Ryan Heaslet, Lucas Lloyd, Steven Emerman The high cost of air quality monitoring stations makes it difficult for citizens or local governments to monitor air quality in their own neighborhoods, especially in low-income communities. The objective of this study was to find a cheaper method of measuring long-term air quality, especially PM-2.5 (concentration of particulate matter smaller than 2.5 microns) and PM-10. The objective was addressed by measuring the magnetic susceptibilities of leaf samples of 12 species of trees collected within a two-mile radius of each of the seven air-quality monitoring stations in Salt Lake and Utah Counties, Utah, over a two-year period. After air-drying and crushing the samples, both low-frequency (0.46 kHz) and high-frequency (4.6 kHz) magnetic susceptibilities were measured with the Bartington MS3 Magnetic Susceptibility Meter. The best correlations between tree leaf magnetic susceptibilities and air-quality parameters were between the three-year average of PM-2.5 and the high-frequency magnetic susceptibility of leaves of pine (\textit{Pinus aristata}) (R$^{2} = $ 0.87, P \textless 0.01) and Norway maple (\textit{Acer platanoides}) (R$^{2} = $ 0.86, P \textless 0.01). The correlation with pine has been used to estimate PM-2.5 in two unmonitored locations heavily impacted by highway traffic (corner of 800 N and I-15 and corner of University Parkway and I-15, both in Orem, Utah). Further results will be reported at the meeting. [Preview Abstract] |
Friday, October 17, 2014 2:50PM - 3:02PM |
D4.00005: A coherent liquid-sodium dynamo to understand the magnetohydrodynamic amplification of magnetic fields Richard Sonnenfeld, Jiahe Si, Stirling Colgate, Arthur Colgate, Joe Martinic, Mark Nornberg Accretion disks of plasma create currents responsible for the huge magnetic fields of active galactic nuclei. Circulating iron creates Earth's magnetic field. The question of how small ``seed'' magnetic fields in conducting fluids/plasmas are amplified by factors of tens to millions is called the ``dynamo problem.'' We have simulated the differential rotation of accretion disks with a ``plasma'' consisting of 125 liters of liquid sodium metal constrained between co-rotating cylinders which produce Taylor-Couette flow at Reynolds numbers up to $10^7$. Given a radial seed field of 10 G, our apparatus converted mechanical to magnetic energy to produce an 80-G toroidal field. This effect (called the $\omega$-effect) is predicted in dynamo theory, but our experiment showed, in 2011, the largest gain obtained by any experiment in the world. We attribute this success to the largely coherent flow field in the instrument. We are now studying the $\beta$-effect, in which fluid turbulence dissipates magnetic energy by increasing the effective resistivity of the fluid. The $\beta$-effect is studied by applying an external B-field pulse and observing its penetration into the liquid sodium flows vs time for varying rates of rotation and levels of turbulence. [Preview Abstract] |
Friday, October 17, 2014 3:02PM - 3:14PM |
D4.00006: Water Entry of Deformable Spheres Tate Fanning, Randy Hurd, Tadd Truscott, Jesse Belden We examine the water entry characteristics and cavity dynamics of highly deformable elastic spheres at high Reynolds numbers (10$^5$) using high-speed photography and image processing techniques. Upon impact normal to a free surface, these elastic spheres undergo significant deformation. We have observed principal stretches on the order of 1.6 diameters for the most compliant spheres. This initial deformation sets up an oscillatory vibration mode in the sphere that persists throughout its descent through the water column. These oscillations disturb normal cavity formation, resulting in the formation of a periodic, nodular cavity. A comprehensive experimental study allows for prediction of cavity shape, pinch off depth, and time to pinch off. Decreasing sphere stiffness results in decreased pinch off depths, and increased time to pinch off over the range of Reynolds numbers tested. [Preview Abstract] |
Friday, October 17, 2014 3:14PM - 3:26PM |
D4.00007: Commercialization of Backwashable Microfiltration Screens Andrew Davis, Nicholas Morrill, Robert Davis, Richard Vanfleet Much of the applied research done in university laboratories is never developed into a usable product. Here I present on the process of commercialization applied physics research and particularly on the path that we have gone through in commercializing my undergraduate research. I've worked for 2 1/2 years as an researching microfiltration screens. Throughout the research process I have hoped that the research I was doing would have practical application. After initial testing on screens we developed, we began looking at commercialization potential of the technology. For the past 6 months we have been looking at different markets and variations on the initial fabrication technique in order to address needs in the 1-10 micron filtration space. We have found considerable traction with self-cleaning backwash filtration system manufacturers. In general these systems currently are only viable for filtration over 50 microns. Using our screen technology this could allow for filtration down to 1 micron. This would open up opportunities for use of these systems in frack water disposal and reuse. In these applications thousands of gallons of produced water are processed daily. Through using our high throughput backwashable screens maintenance and cost could be reduced. [Preview Abstract] |
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