Bulletin of the American Physical Society
Annual Meeting of the Four Corners Section of the APS
Volume 58, Number 12
Friday–Saturday, October 18–19, 2013; Denver, Colorado
Session K6: Industrial and Applied Physics |
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Chair: Matt Kim, QuantTera Room: 151 |
Saturday, October 19, 2013 11:15AM - 11:39AM |
K6.00001: The Use of Plasma Based Catalysts in the Automotive Industry Invited Speaker: Maximilian A. Biberger Traditionally catalysts for the automotive industry are being made by using wet chemistry, i.e. PGM's (Platinum Group Metals) are being dissolved in acids and then impregnated onto porous, micron sized substrates. This technology is serving the industry well, however as demand for more fuel efficient cars as well as Hybrid cars increases, this technology begins to start showing limitations. The limitations are: a) Large amounts of precious metals being consumed, resulting in more than USD 10B/yr, which increases the cost of the vehicle and b) wet chemistry based catalysts have the tendency to age, i.e. the precious metal nano particles agglomerate during operation and the catalytic properties of the catalyst diminishes. In the present paper a novel method of manufacturing catalysts is presented. This technology is based on plasma synthesis instead of wet chemistry, resulting in thermally much more stable catalysts that have the potential to overcome above mentioned shortcomings and allow car manufacturers to introduce more fuel efficient cars as well as reducing the amount of precious metals needed. The latter is of particular interest in Hybrid cars: Due to the combination of a combustion engine and electric engine, the exhaust is much colder than in traditional cars, hence much more precious metal per catalytic converter is required. Another aspect discussed in this paper are the challenges related to the introduction of a new and novel technology into the automotive industry. [Preview Abstract] |
Saturday, October 19, 2013 11:39AM - 11:51AM |
K6.00002: Wavelength Detection from Filtered Photodiodes Nils Otterstrom Filtered photodiodes coupled with developed algorithm reveal potential as inexpensive wavelength meter. Externally timed integration with microprocessor allows variable integration lengths and exports data through USB. Algorithm compares data to calibrated intensity curves and minimizes error to compute wavelength. [Preview Abstract] |
Saturday, October 19, 2013 11:51AM - 12:03PM |
K6.00003: Mode transitions in strings with an abrupt change in mass density Tyler Allen, Nathaniel Wells, Bonnie Andersen Previous research with bottle-shaped thermoacoustic prime movers has revealed hysteresis with transitions to higher modes as the cavity length is varied. A string with an abrupt change in mass density was studied to investigate potentially similar behavior. Three base guitar strings were studied at three different tensions with weights of 25, 30, and 35 lbs. Each string consisted of a ``thin side'' that was stripped to the stainless steel core and a ``thick side'' with an outer wrapping of nickel around the core. The strings studied had diameters of 0.65, 0.45, and 0.50 mm on the thin side and 2.14, 1.31, and 1.24 mm on the thick side, respectively. An anchor was attached on one end of a short board with a pulley at the other for hanging the weight. The end of the thick side of the string was attached to the anchor, and the string was guided over the pulley, with the change in mass density occurring approximately 12 cm from the pulley. Measurements were taken after placing a glass jar under the thick end of the string, between 42 cm and the position of the change in mass density, in 3-cm steps. The string was plucked and the dominant frequency was recorded with a microphone at each location. Frequency data is generally consistent with a solution to a 1D wave equation. Preliminary results indicate mode transitions occurring for all strings, with several hysteresis region candidates. [Preview Abstract] |
Saturday, October 19, 2013 12:03PM - 12:15PM |
K6.00004: Developing an amplitude compensation method for obtaining high-resolution acoustic directivities from played musical instruments Nicholas J. Eyring II, William J. Strong, Nathan G.W. Eyring When considering the acoustic radiation of a source, far-field directivity patterns are useful graphical representation of sound propagation in a given direction and frequency. Directivity measurements of played musical instruments present several experimental challenges, including the need for musicians to play consistently and reproducibly. Some researchers have chosen to implement fixed, limited-element microphone arrays surrounding instruments for rough directivity assessments. Unfortunately, with practical numbers of microphones, this approach limits spatial resolution and field decomposition bandwidth. Higher-resolution data may be obtained with a given microphone count by rotating a musician in sequential azimuthal angle increments under a fixed semicircular microphone array. The musician plays a selected note sequence with each increment, but corrections must be made for playing variability. For 5$^\circ$ resolution this results in 2664 measurements with M=37 in the polar angle $\theta$ and N=72 in the azimuthal angle $\phi$. This paper explores the development of an amplitude compensation method that utilizes reference microphones that are fixed in the rotating reference frame. By approximating the reference and arc microphones as the input and outputs of an LTI system, transfer functions, $\hat{H}_{MN}$, may be computed. The resulting set of $\hat{H} _{MN}$ are invariable under scalar changes in amplitude that are identical at both the reference and arc microphone positions. An experimental validation using a source with random variations in amplitude will be presented. [Preview Abstract] |
Saturday, October 19, 2013 12:15PM - 12:27PM |
K6.00005: Circular orbits on a warped spandex fabric Chad Middleton, Michael Langston Here we investigate, both theoretically and experimentally, the circular-like orbits of a marble rolling on a warped spandex fabric. We show that the mass of the spandex fabric interior to the orbit of a marble influences the motion of the marble in a nontrivial way. In fact, the effect of the mass of the spandex fabric on the orbiting marble can actually dominate over that of the mass of the central object, for small enough central mass. By measuring the stretch of the spandex fabric near the central object for a variety of masses, we show that the modulus of elasticity describing the spandex fabric is not constant and is a function of the stretch. Lastly, we compare the Kepler-like expression for circular orbits of a marble on the warped spandex fabric in the small curvature regime to the Kepler-like expression for circular orbits about a spherically-symmetric massive object in the presence of a constant vacuum energy, as described by general relativity. [Preview Abstract] |
Saturday, October 19, 2013 12:27PM - 12:39PM |
K6.00006: Why there is no noon-midnight red shift in the GPS Neil Ashby, Marc Weiss Although the effects of solar (and lunar) gravitational potentials on the frequencies of orbiting Global Positioning System (GPS) clocks are actually no more than a few parts in $10^{15}$, a na\"ive calculation appears to show that such effects are much larger, and depend on whether the orbiting clock is between the earth and the sun, or on the side of the earth opposite to the sun. Consequently questions about whether such effects have been properly accounted for in the GPS continue to arise. This issue has been discussed in a misleading way in terms of cancellations arising from a second-order Doppler shift in the literature for almost 50 years. The purpose of this article is to provide a correct argument, based on fundamental relativity principles, so that one may understand in a simple way why the effects of external solar system bodies on orbiting or earth-bound clocks in the GPS are so small. The relativity of simultaneity plays a crucial role in these arguments. [Preview Abstract] |
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