Bulletin of the American Physical Society
Joint Fall 2011 Meeting of the Texas Sections of the APS, AAPT, and Zone 13 of the SPS
Volume 56, Number 7
Thursday–Saturday, October 6–8, 2011; Commerce, Texas
Session L1: General Physics & Applications II |
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Chair: Michael Sadler, Abilene Christian University Room: Sam Rayburn Center Second Floor, Room Innovations A |
Saturday, October 8, 2011 9:25AM - 9:37AM |
L1.00001: Aerodynamic Self Excitation of a Taut Elastic Ribbon Sam Matteson, David Lambert The investigators analyzed, both theoretically and experimentally, the motion of a taut ribbon of elastic material in an air stream to show that the resulting standing-wave motion is a manifestation of self excitation. Self excitation is a phenomenon in which the oscillatory motion of the object extracts energy from a steady energy source. Such a ribbon simulates the motion of the human vocal folds as well as that of unstable bridge ``galloping,'' such as is famously exemplified in the Tacoma Narrows bridge collapse. The phenomenon discussed in this talk is also relevant to aerodynamic flutter and the ``quaking'' of leaves of trees in the breeze. Chief among the findings of this work is the origin of inharmonic modes of oscillation of a self excited ribbon. [Preview Abstract] |
Saturday, October 8, 2011 9:37AM - 9:49AM |
L1.00002: A Newtonian Theory of the Fizeau Experiment James Espinosa, James Woodyard In 1965, Fox reviewed the experiments considered as evidence against Ritz's theory of emission and found almost all of them to be compatible with Ritz's theory by applying a simple modification. His critiques have been restated by some graduate textbooks such as Jackson's Classical Electrodynamics. Unfortunately, the vast majority of textbooks at the undergraduate level have entirely ignored Fox's paper. Over the past decade, we have continued the work of Ritz into gravitational and atomic phenomena with great success but now revisit some of Fox's reservations about the emission theory of electromagnetism. His most serious argument against Newtonian physics was Fizeau's experiment, which both he and Einstein considered incompatible with classical kinematics. Unknown to Fox, the Italian physicist Carlo Somigliana published a paper in 1922 reminding the physics community that this ``inconsistency'' had been solved 30 years before Einstein by Woldemar Voigt. We will review this important paper and discuss possible reasons for Fox's ignorance of this important contribution. [Preview Abstract] |
Saturday, October 8, 2011 9:49AM - 10:01AM |
L1.00003: Signal induced breaking of universal noise statistical properties Luca Perotti, Daniel Vrinceanu, Daniel Bessis We consider the Z-transform of a random time series, extension to the complex plane of the dicrete time Fourier transform. Regardless of the specific characteristics of the random signal itself, the singularities of the Z-transform are universally distributed. Addition of a regular signal to the random one locally perturbs this distribution. Deviations from universality therefore indicate the presence of regular signals even when low signal to noise ratio prevents their direct detection. We present examples suggesting that these properties can lead to practical applications such as the detection of faint transients in heavy noise. [Preview Abstract] |
Saturday, October 8, 2011 10:01AM - 10:13AM |
L1.00004: Lunar in situ resource utilization by activated thermites Mkhitar Hobosyan, Karen Martirosyan NASA's anticipated returns to the Moon by 2020, subsequent establishment of lunar in situ resource utilization technologies are essential. The surface of Moon is covered with small eroded particles of regolith called lunar dust that adheres electro-statically to everything coming in contact with it, and is of much concern for future lunar base because of its continual mitigation. The next major concern is the protection of equipment and personnel in long term expeditions from harmful UV radiation, which can be made by constructing protective buildings. For construction of permanent structures it is highly desired to have regular shaped sintered regolith with utilization of local materials and with minimum energy consumption. In this study the concept of sintering of lunar regolith with activated thermite reactions is discussed. The thermodynamic calculations as well as the experimental procedure is provided to prove the effectiveness of activated thermites for regolith sintering using local lunar resources with a low (15 wt. {\%}) concentration of aluminum or magnesium. The thermite method is much more energy efficient than the other sintering methods suggested in literature. [Preview Abstract] |
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