Talk:Self-oscillation

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May I suggest merging this with the Hunting oscillation article. Gordon Vigurs 21:26, 8 May 2006 (UTC)

The Hunting oscillation article is rather long (and very good!) and "hunting" is also a term used more widely for self-exciting oscillations, including in electronics. But then again, there are some self-exciting oscillations, for example shimmy in automotive drivelines, that are not called "hunting". But then again, the shimmy article says: For the engineering effect, see Hunting (engineering). I think that we need an overall article on self-exciting oscillation that then unpicks the nomenclature and refers to specific detailed articles. Cutler 22:52, 8 May 2006 (UTC)

Oh, and there's aeroelasticity#flutter. Cutler 08:05, 9 May 2006 (UTC)

Self-exciting oscillation; other important instances

I totally agree with the previous suggestion to re-structure starting with an article on self-exciting oscillations. This will make it possible to explain that self-exciting oscillations are a logical consequence of systems which are described by a closed loop of time-lagged differential equations, i.e. where a change in variable N is driven by a change in variable N+1 but only after a time delay, a change in variable N+1 is driven by a change in variable N+2 but only after a time delay, .... a change in variable N is driven by a change in variable N+x but only after a time delay.

The set of articles should also point out the importance of self-exciting oscillations in fields other than engineering, for example:

• Boom-bust cycles in economics. No doubt in practice these are partly due to herd psychology, but closed loops of time-lagged differential equations are a sufficent explanation.
• Population booms and collapses in biology. For example back when personal computers were puny there was a text-based simulation of foxes and rabbits where an increase in the rabbit population caused a delayed increase in foxes, which caused a delayed decrease in rabbits, which caused a delayed decrease in foxes, which caused a delayed increase in rabbits, etc.
• Possibly sunspot cycles (the sun is so vast that the propagation of imbalances and feedback mechanisms takes thousands to millions of years).

I also suggest further simple examples in engineering, for example:

• Early central heating thermostats were guilty of hunting because they responded too quickly. The problem was overcome by hysteresis, i.e., making them switch state only when the temperature varied from the target by a specified minimum amount.
• Steering of vehicles when course corrections are delayed. There are many examples of this, ranging from light aircraft in a strong wind (I've experienced this at the controls of a glider) to erratic steering of road vehicles by a driver who is inexperienced or drunk.

Philcha 15:44, 12 October 2006 (UTC)

Proposed merger

Fine, provided that the detailed railway engineering diagrams and calcuations go at the bottom - "hunting" is used in a wide range of contexts. Philcha (talk) 10:41, 20 April 2008 (UTC)

Yes merge "hunting oscillation" into "hunting" as a subsection - ie hunting (rail) or hunting (vehicles)77.86.67.245 (talk) 21:11, 11 April 2009 (UTC)

Boom-bust cycles in economics

"No doubt in practice these are partly due to herd psychology, but closed loops of time-lagged differential equations are a sufficient explanation. In economics the time delay is caused by the need for individuals and organizations to gather information and make decisions. The classic example is the stock market: prices start rising, after a while investors notice this and increase their buying, this forces prices up, etc. - until something (e.g. a scandal or an economic crisis) stops prices from rising, after a while investors decide to sell, etc."

From this perspective all it is is exponential change. To be more specific - prices rising causing increased buying causing prices to rise... is the exact opposite of oscillation. It may be possible to describe economic cycles in terms of self-exciting oscillation but you would have to assert that the greater a boom is, the more likely "a scandal or economic crisis" is to occur. Without that relation it's just exponential change and random external forces acting on a system (ie positive feedback).--75.159.246.68 (talk) 10:29, 3 May 2010 (UTC)

Renaming and expanding article

I think that this article should be re-named "Self-oscillation". This is closer to the term used in Russian by Andronov and his collaborators (Автоколебания), and also more standard in the recent scientific literature. A review article that might be useful for expanding the discussion here and providing references is:

• Jenkins, Alejandro (2013). "Self-oscillation". Physics Reports. 525 (2): 167–222. arXiv:1109.6640. Bibcode:2013PhR...525..167J. doi:10.1016/j.physrep.2012.10.007..

- Eb.hoop (talk) 19:00, 8 October 2013 (UTC)

If there are no objections to re-titling this article "Self-oscillation", I will make the corresponding move in a couple of weeks' time. -Eb.hoop (talk) 20:10, 11 December 2013 (UTC)

Inserting an application to electrodynamics

Hi, everyone. A new application of self-oscillation has been recently published in a notable journal (https://doi.org/10.1007/s11071-020-05928-5) in connection with classical electrodynamics. I am the author of the paper, and therefore I am not the person allowed to upload the reference, since a COI is at stake. But perhaps somebody could check contents and simply add some few lines in the section entitled "Examples in other fields", which says something like:

Charged extended particles can experience self-oscillatory dynamics as a result of classical electrodynamic self-interactions \cite{}. This trembling motion has a frequency that is closely related to the zitterbewegung frequency appearing in Dirac's equation. The mechanism producing these fluctuations arises because some parts of an accelerated charged corpuscle emit electromagnetic perturbations that can affect another part of the body, producing self-forces.

The notion of self-oscillation has not received sufficient attention among the community of fundamental physics and it can help to introduce this transcendental concept of nonlinear dynamical systems to such community. Sincerely Alvaro12Lopez (talk) 13:37, 13 September 2020 (UTC)