Bulletin of the American Physical Society
Joint Fall 2009 Meeting of the Ohio Sections of the APS and AAPT
Volume 54, Number 9
Friday–Saturday, October 9–10, 2009; Delaware, Ohio
Session C3: Nonlinear Dynamics and Education |
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Chair: Barbara Andereck, Ohio Wesleyan University Room: Conrades-Wetherell Science Center 161 |
Saturday, October 10, 2009 8:00AM - 8:12AM |
C3.00001: ``Devil's staircase'' in nanomagnetism: fractional synchronization of a nonlinear spin-torque nano-oscillator Sergei Urazhdin, Phillip Tabor, Andrei Slavin, Vasyl Tyberkevych When an oscillator is driven by a periodic external force, the oscillation can become synchronized in a certain phase and frequency relationship with that force. At the main resonance, the frequency $f$ of the oscillation becomes equal to the frequency $f_{e}$ of the driving signal. An infinite number of synchronization regimes with rational values of $r=f_{e}$/$f$ (``Devil's staircase'') develop at large driving amplitudes. For magnetic nano-oscillators driven by spin transfer effect synchronization has been demonstrated only at the main resonance, when $f_{e}$ is close to the auto-oscillation frequency $f_{0}$. By using a new device geometry utilizing a microwave field as the driving force, we demonstrate the ``Devil's staircase'' in magnetic nano-oscillators. Analysis shows that fractional synchronization becomes possible only due to the simultaneous action of both the microwave magnetic field and the microwave current, and is characteristic of the complex nonlinear nature of the magnetic precession. [Preview Abstract] |
Saturday, October 10, 2009 8:12AM - 8:24AM |
C3.00002: Synchronization of Metronomes and Moons Barbara Andereck, Anne Benjamin, David Carpenter When (nearly) identical non-linear oscillators are coupled they can adjust their frequencies and settle into synchronous motion. The path to synchronization exhibits interesting and sometimes intricate oscillations of its own. We have studied the nature of this path for two systems: mechanical oscillators in the form of identical metronomes and orbiting satellites, specifically Io and Europa, the two inner Galilean satellites of Jupiter. We report the basic behaviors observed and dependence of key parameters of these behaviors on physical properties of the system and initial conditions. [Preview Abstract] |
Saturday, October 10, 2009 8:24AM - 8:36AM |
C3.00003: Using letters to the editor to try to bring science to the public Gordon Aubrecht The local paper here, the Delaware Gazette, publishes many letters from global warming skeptics and people ignorant of energy policy. I explain how I attempt to bring some sense to the situation through reply letters to the editor. Scientists need to express scientific views in public as our duty to fellow citizens. [Preview Abstract] |
Saturday, October 10, 2009 8:36AM - 8:48AM |
C3.00004: Another year of IMPACT2 Gordon Aubrecht IMPACT2 is a program at Marion's Grant Middle School that involves almost every science teacher. Some achievements of the first year will be given as well as the plan for the second year of the grant. [Preview Abstract] |
Saturday, October 10, 2009 8:48AM - 9:00AM |
C3.00005: Independent measurements of the frequency and wavelength of electromagnetic waves Craig Howald Very few measurements that directly investigate the frequency of electromagnetic waves are accessible to undergraduate or high school laboratories because of the expense of most spectrum analyzers as well as the extremely high frequencies of many electromagnetic waves. However, an affordable setup for measuring electromagnetic wave properties, including frequency and wavelength, can be made using a wireless network spectrum analyzer. Capabilities of an inexpensive spectrum analyzer are examined and illustrative samples of wave property measurements are presented. These allow determination of the speed of propagation so that comparison with the speed of visible light can help integrate student understanding of the electromagnetic spectrum. [Preview Abstract] |
Saturday, October 10, 2009 9:00AM - 9:12AM |
C3.00006: Gains in Content Knowledge, Confidence and Comfort Levels from a Physical Science Course Laura Van Wormer, Roxanne Sorrick Physical Science for Everyday Thinking (PSET) is a guided inquiry approach to teaching physical science. Pre and post survey data were collected during four years of using PSET. The course was taught in an intensive format at a small, private liberal arts college; at least half the students were education majors. The surveys assessed content knowledge and confidence in the answers, attitudes toward science and understanding of the process of learning science. Analysis indicated significant increases in content knowledge, confidence in content knowledge and comfort levels with physical science; also significant changes in identification as a science person, what is a fact, objectivity of scientists and science as a solitary pursuit. [Preview Abstract] |
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