Talk:Hysteresis

Number of section levels

At present, the article contains 15 subsections, with no inner hierarchy. The article would be clearer if all the examples of hysteresis pertaining to physics were grouped under one section, will subsections as appropriate, and the same for the biological examples. As it is, the contents is just a run-on list. —Preceding unsigned comment added by 87.96.226.195 (talk) 00:14, 14 September 2009 (UTC)

Examples

Economics - The example given relates more to inertia than hysteresis.

For hysteresis in an economic context, see:

• Whitwell, J. (1990), 'The Rogernomics Monetarist Experiment', in Holland, M. and Boston, J. (eds), The Fourth Labour Government, Oxford Uni Press (2nd ed.)
• Dalziel, P. (1992), 'National's Economic Strategy', in Boston, J. and Dalziel, P. (eds), The Decent Society?, Oxford Uni Press

Kabl00ey 01:32, 21 August 2005 (UTC)

Also, "There is now considerable empirical support, at least in some countries, for thus hysteresis phenomenon, meaning that the outcome of policies depends on the path taken to reach the outcome" - Dalziel, Paul. "The Reserve Bank Act." In State and Economy in New Zealand, edited by Brian Roper & Chris Rudd. Oxford: Oxford University Press, 1993.

Empirical evidence cited: Blanchard and Summers (1987, 1988), Cross (1988), R. Gordon (1988, p.303), W. Mitchell (1987). [Sorry these aren't full references, I'm missing the bibliography for the text I got these from].

kabl00ey 23:00:26, 2005-09-06 (UTC)

Plant breeding - This page is linked from the green revolution where it is said that F1 hybrids exhibit hysteresis. Can this be explained here?

Minor change under 'Magnetic Hysteresis' section

Changed: thinness to thickness in "The 'thickness' of the middle bit of the S describes the amount of hysteresis." BananaManCanDance 15:01, 15 March 2006 (UTC)

Idealised hysteresis curve

Actually I think the curve starting at the origin in the RH diag should not be parallel to the major loop curves but should bend over to the right earlier and meet the other two curves at their intersection --Light current 17:01, 3 June 2006 (UTC)

I have removed this diag from the page as it is not correct as explained above.--Light current 22:04, 18 June 2006 (UTC)

I have removed this diagram for the second time. Pleas do not reinsert without a reference show it is correct. My reference showing the proper cureve is on p202 of Electromagnetism (2nd ed) by Grant and Philips, pub by John Wiley 1990. --Light current 01:30, 19 June 2006 (UTC)

[1] [2] [3] [4] [5] [6] [7] — Omegatron 02:37, 19 June 2006 (UTC)

Yes all of the above show the correct diagrams. Can you not see the difference in the one I removed? *In the meantime I suggest we replace it by one of the ones you have linked above. You choose!--Light current 02:46, 19 June 2006 (UTC)

And what is this great difference that completely invalidates the image?

Too bad we can't use those because we don't have the copyright on them, eh? — Omegatron 03:04, 19 June 2006 (UTC)

The difference is that in the diagram I removed, the initial magnetisation curve (the one starting at the origin) is shown as perfectly linear (esp if projected backwards). It certainly isnt in reality. That is why for instance you need bias on your tape recorder heads to overcome this nonlinearity in the magnetic particles on the tape. Secondly, it shows the magnetic material approaching saturation at two different values of H, depending on where you start from. I believe saturation always occurs at the same value of H for any given material. I suggest the diag is withdrawn until it can be REdrawn correctly if none of the others can be used. 8-|--Light current 03:14, 19 June 2006 (UTC)

See here for instance [8]--Light current 03:18, 19 June 2006 (UTC)

I will update the image eventually, but it's perfectly accurate for showing the way you move around the curve. [9] [10] [11] [12] [13] [14] [15] [16] — Omegatron 14:00, 19 June 2006 (UTC)

Misleading diagram

Honestly 'O' I think the diagram as it stands is misleading the readers into thinking that the initial magnetisation curve of ferromagnetic material is linear. It isnt! 8-(--Light current 14:10, 19 June 2006 (UTC)

How can you justify the inclusion of this misleading image in view of Jimbo's directive?--Light current 23:48, 23 June 2006 (UTC)

How can you justify removing the picture in light of the fact that this is an encyclopedia? It's been there for more than two years with no complaints about accuracy or it being "misleading". You're harming the encyclopedia by removing valuable information for trivial reasons.

As you can see from my multiple references, a simplified graph like this is typical and adequate for explaining the concept of hysteresis, and varies less from a real magnetic curve than the real curves vary from each other. The image was not originally an image of magnetic hysteresis, but just an example of a general hysteresis curve. Someone thought it was close enough to put in the magnetic section when the article was divided into sections.

I've updated the image to address your minor concern about the curve at the origin, though it was a waste of my time, as the image will eventually be updated (probably by me) to be even more accurate, making the work I just did pointless. — Omegatron 04:06, 24 June 2006 (UTC)

Thank you 'O' It is certainly better than it was. I dont know how the image was created, so I didnt know how difficult it was to modify. --Light current 23:09, 24 June 2006 (UTC)

magnetic hysteresis at 50 Hz?

The loops in 'magnetics hysteresis' section are said to be obtained in 50 Hz tests. In this case, dynamic effects are also present, and they contribute widening the loops. I believe international standards state that magnetic hysteresis loops should be obtained at 1Hz. Can anyone correct me if I'm wrong?

Yes dynamic effects will be present although I dont know how the shape of the loops changes with freq. It is known that the hysteresis losses go up with frequency which could heat up the material.

Actually, hysteresis is function of material magnetization. It does not matter the frequency with which H-B is varied, hysteresis losses (measured in joules and not watts [equivalent to the area confined by the loop]) do not change. Dynamic losses however are created by currents circulating within the ferromagnetic material and have nothing to do with 'magnetics hysteresis'. Therefore, the loops obtained for 50 Hz showed in the figure are not for magnetic hysteresis and perhaps should be placed in a different section.

What exactly does this mean?

'hysteresis is function of material magnetization'

--Light current 23:18, 21 June 2006 (UTC)

Sorry, I checked Bertotti's book (book) and he calls indeed all loops 'hysteresis loops'. I was thinking in terms of loss separation in which

$P=P_{hyst}+P_{dyn}$

${\frac {P}{f}}=C_{0}+(C_{1}f+C_{2}{\sqrt {f}})$

"Matric" Potential Hysteresis (possible chronic spelling error)

I noticed a seeming misspelling on a related page (Water potential) and thought to correct it, until I followed a link to this page/section, where I saw the word (matric) used over and over. I tried looking it up in online dictionaries, but it was not found. Could "matric" be a chronic misspelling? -- Tuvok^^{Talk|Desk|Contribs}  01:58, 13 October 2006 (UTC)

Matric Potential Hysteresis...

Matric is not mis-spelled. However, matric potentials should all be negative unlike the value of '5KPa' you have used in this article —Preceding unsigned comment added by 128.243.220.41 (talk)

Respiratory

What about hysteresis seen during inflation/deflation of lung tissue?

Pressure Sensors, Strain gauges

These too.

Basic definition of hysteresis is in hieroglyphs

The first sentence uses the terms

• path-dependence
• rate-independent memory

which as a general reader I have no clue what they are.

Can someone who knows the subject write a definition that is more understandable to a general audience?

Federico Grigio, alias Nahraana (talk) 18:20, 20 March 2008 (UTC)

A formal definition

Based on my limited knowledge, following dissertaion discussed about a definition of the hysteresis: JinHyoung Oh, "Modeling, identification, and control of rate-independent and rate-dependent hysteresis", 2005. —Preceding unsigned comment added by 210.93.51.11 (talk) 06:23, 8 September 2008 (UTC)

Circular reference

When discussing the magnetic hysteresis, there is a link to Hysteresis loss that simply redirect to this same article. --Gonfer (talk) 16:45, 22 April 2009 (UTC)

Very misleading opening paragraph, wrong in its natural interpretation

The current opening paragraph is misleading:

"A system with hysteresis has memory. This means that the system may be in more than one state, and that the system's current state is independent of its input at the current instant in time. A system with hysteresis is said to exhibit path-dependence, or "rate-independent memory". (Mielke & Roubicek 2003)."

A system cannot "be in more than one state" unless you are comparing the system state at different times, which is NOT what is implied. What I think is meant is that given the inputs it is impossible to tell what state the system is in without additional history information.

Ewolin (talk) 20:50, 14 July 2009 (UTC)

That has changed quite a bit, undoubtedly for the better, but I liked "A system with hysteresis has memory." It is mnemonic when one is thinking about similar words (as one does in genetics, where "hysteresis" is seldom used). Nadiatalent (talk) 13:47, 12 December 2009 (UTC)

I have changed this back, since you commented. I agree it was a good mnemonic, but it seemed a little simplistic without qualification. See what you think now? Thudso (talk) 16:05, 12 December 2009 (UTC)

General semantic and/or typographic issues

Because the subject is not one I natively understand, while reading it what I DO note are apparent errors in semantics/syntax/etc. The examples which I post here are for others to correct if/as necessary:

The word hysteresis is often used specifically to represent rate-independent state. [either A state or STATES]

Not all systems with state (or, equivalently, with memory) have this property; for example, a linear low-pass filter has state, but its state is rate-dependent. [Here the use of "state" makes the issue in the above sentence even more problematic. I make no changes as this may be a use of language specific to this discipline.]

(with the model, substitution of rectangle, triangle or trapezoidal pulses instead of the harmonic functions also allows to built piecewise-linear hysteresis loops frequently used in discrete automatics). More formal mathematical theory of systems with hysteresis was developed in 1970s, by a group of Russian mathematicians, which was led by Mark Krasnosel'skii, one of the founders of nonlinear analysis.

[ rectangle, triangle or trapezoidal � should these not read "rectangular, triangular and trapezoidal pulses"? and the remainder of the section quoted appears to be from a non-native speaker of English. The problems will be evident and their correction best left to others more senior as regards their editorship.]

For reasons not understood I am unable to activate BOLD or ITALIC functions to make the above clearer. Beofluff (talk) 01:57, 3 September 2009 (UTC)