Entrainment (physics)
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It has been suggested that this article or section be merged into Injection locking. (Discuss) Proposed since July 2011. |
- See entrainment for other types.
Entrainment has been used to refer to the process of mode locking of coupled driven oscillators, which is the process whereby two interacting oscillating systems, which have different periods when they function independently, assume a common period. The two oscillators may fall into synchrony, but other phase relationships are also possible.
The system with the greater frequency slows down, and the other accelerates. Christian Huygens, a notable physicist, introduced the concept after he noticed, in 1666, that two pendulum clocks had moved into the same swinging rhythm, and subsequent experiments duplicated this process. Notably, the two pendulum clocks stabilized not in synchrony, but in an "odd sympathy" or antiphase. They satisfy the definition of entrainment because they have the same period, even though they have opposite phase. The accepted explanation for this is that small amounts of energy are transferred between the two systems when they are out of phase in such a way as to produce negative feedback. As they assume a more stable phase relationship, the amount of energy gradually reduces to zero. In the realm of physics, Huygens observations are related to resonance and the resonant coupling of harmonic oscillators, which also gives rise to sympathetic vibrations.
A 2002 study of Huygen's observations show that an antiphase stable oscillation was somewhat fortuitous, and that there are other possible stable solutions, including a "death state" where a clock stops running, depending on the strength of the coupling between the clocks.[1]
Mode locking between driven oscillators can be easily demonstrated using mechanical metronomes on a common, easily movable surface. [2] Such mode locking is important for many biological systems including the proper operation of pacemakers.[3]
The use of the word entrainment in the modern Physics literature most often refers to the movement of one fluid by another. The use of the word to refer to mode locking of non-linear coupled oscillators appears mostly after about 1980, and remains relatively rare in comparison.
A similar coupling phenomenon was characterized in hearing aids when the adaptive feedback cancellation is used. This chaotic artifact (entrainment) is observed when correlated input signals are presented to an adaptive feedback canceller.
[edit] See also
- Entrainment (hydrodynamics)
- Injection locking
- Brainwave synchronization
- Synchronization of chaos
- odd sympathy
[edit] Cited References
- ^ M Bennett, M F Schatz, H Rockwood, andK Wiesenfeld, Proc. Roy. Soc. Lond. A 458 (2002) 563-579.
- ^ J. Pantaleone, "Synchronization of Metronomes," American Journal of Physics, vol 70 (2002) 992-1000.
- ^ G. B. Ermentrout and J. Rinzel, "Beyond a pacemaker's entrainment limit: phase walk-through," American Journal of Physiology - Regulatory, Integrative and Comparative Physiology, Vol 246 (1984) R102-R106.
[edit] Additional References
Filter Entrainment Avoidance with a Frequency Domain Transform Algorithm [1]
Entrainment Avoidance with Pole Stabilization [2]
Entrainment Avoidance with a Transform Domain Algorithm [3]
Entrainment Avoidance with an Auto Regressive Filter [4]
