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The first sentence uses the terms
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)
Seconded. It's a difficult paragraph to digest for someone brand new to the field. Noxxeexxon ( talk) 17:46, 22 September 2011 (UTC)
Hysteresis refers to the fact that different graphs of force vs. compression are obtained depending on whether the force is increasing or decreasing. A graph of force vs. compression ... for a metal spring is a straight line, and it is the same regardless of whether the force is increasing or decreasing. A graph of force vs. compression for a baseball...is a curved line and its shape does depend on whether the force is increasing or decreasing."
This is closer to what we need here, but has too much "whether" in it. -- Wtshymanski ( talk) 02:01, 23 September 2011 (UTC)
The associated section describes the unloading and loading of weights attached to an "idealized" rubber band. Intuitively, as the rubber band is loaded, its length will extend and, as its length extends, its elasticity will decrease. As the elasticity of the rubber band decreases, the rate at which its length increases with additional loads likewise decreases. One would, therefore, expect, in the aforesaid figure, that the Force-Extension curve of the loading phase to approach a limiting Extension value. As the load or Force exerted on the band increases, the Extension will increase, eventually approaching, but never exceeding that limiting value. The Force-Extension curve should, therefore, eventually inflect upward. This is not depicted in the figure. The unloading phase would occur in an analogous manner.
The curve should resemble this:
http://www.revisionworld.co.uk/files/strain_33.gif —Preceding unsigned comment added by Atlasfugged ( talk • contribs) 06:05, 10 October 2010 (UTC)
I can't remember whether this has any bearing on the matter, but the graph currently in the article is for Force against Extension, and the one linked above is for Tensile Stress against Tensile Strain. I recall that there are differences between the two types of graph, but I do not recall if there are differences between shapes of the curves. Viola16 ( talk) 11:45, 21 November 2010 (UTC)
That's a good point about the axes. Stress, as I know it, is somewhat like Force / Area. Strain is somewhat like Length / Initial length. So the graphs appear at firs to be describing the same things. Of course, true vs engineering stress/strain should be specified, as this difference may influence the shape of the loading curves. —Preceding unsigned comment added by 129.138.44.221 ( talk) 21:21, 22 November 2010 (UTC)
Force vs Extension is the same thing as stress vs Strain, except it is normalized differently. Area is assumed to be constant for engineering strain, so Stress=Force/Area represents the same thing as Force. The same goes for Strain=Extension/OriginalLength. OriginalLength is a constant and therefore the titles of the graph are irrelevant. The real question becomes what level of knowledge should be required for the page. Despite being an engineer, I'd leave it as is and go with Force vs Extension. Second, the difference in the two curves that Viola16 mentioned has more to do with the specific material and loading that is applied. Both curves are not valid hysteresis loops despite them looking slightly differently. —Preceding
unsigned comment added by
66.214.14.128 (
talk)
05:08, 5 April 2011 (UTC)
The two phenomena are closely related (at least, in the area of electronic circuits). Any amplifying circuit with positive feedback having a loop gain B.A > 1 possesses hysteresis and v.v., any circuit with hysteresis is an amplifying circuit that is comprised by such a positive feedback. IMO it is impossible to separate them (to have a hysteresis without positive feedback and feedback without hysteresis); we can use positive feedback to obtain hysteresis.
A proportional (fully analog) thermostat is an amplifier (comparator) with only a "global" negative feedback (consisting of cascaded heater, an object and a thermo sensor). The comparator of the simpler bistable thermostat has in addition a "local" positive feedback that forces the transition between the two supply rails and creates the needed hysteresis. Another example: op-amp relaxation oscillator. But how does the positive feedback do this magic? How do we obtain hysteresis by applying feedback? How do we create dual-threshold circuits? How do we convert a one-threshold circuit into a two-threshold one?
Dynamic threshold. The first trick is very simple and intuitive - when the input voltage crosses the threshold in some direction the very circuit changes slightly its own threshold to the opposite direction (i.e., it subtracts voltage from the threshold that is equal to adding voltage to the input voltage). So, the output affects the threshold and do not impact on the input voltage. These circuits are implemented with differential amplifier with series positive feedback where the output is connected to the non-inverting input and the input - to the inverting input. In this arrangement, the humble loop forms the needed summing circuit in the figure (the circle with "+" inside). Examples: classic emitter-coupled transistor Schmitt trigger, op-amp inverting Schmitt trigger, etc.
Modified input voltage. The second technique is opposite - when the input voltage crosses the threshold in some direction the circuit changes slightly the very input voltage in the same direction (i.e., it directly adds voltage to the input voltage). In this case, the output affects (helps) the input voltage and do not affect the threshold. These circuits can be implemented by a single-ended amplifier with parallel positive feedback where the output and the input source are connected through resistors to the non-inverting input. Now, the two resistors form the needed summing circuit (the circle with "+" in the figure). Examples: collector-base coupled transistor Schmitt trigger, op-amp non-inverting Schmitt trigger, etc.
From the feedback view, both the techniques above are the same - systems with positive feedback that is out of control. In both the circuit, the output voltage increases the derivative (difference) input voltage of the comparator (not of the whole circuit!) by decreasing the threshold or by increasing the circuit input voltage. The threshold and memory properties are incorporated in one element (two in one:)
Two different static thresholds. In this case, the threshold and memory properties are separated. The two different thresholds are created by separate ordinary open-loop comparators (without hysteresis) that drive an RS trigger (2-input memory cell). Again, there is a positive feedback but now it is concentrated only in the memory cell. Example: 555 timer. Circuit dreamer ( talk, contribs, email) 22:25, 12 November 2010 (UTC)
(the text below is copied from memristor talk)
I do not share Chua's, Ventra's and others' (including memristor) assertions about the (unconditional) existence of hysteresis in memresistive, memcapacitive and meminductive elements (see for example [2]). Hysteresis is a rate-independent phenomenon like nonlinear resistance. This means that there is no matter if we drive a hysteretic element by slow (DC) or rapidly (AC) changing input quantity; it will show different forward/backward paths (what is the definition of hysteresis) of its IV curve in both the cases. This is not true for a volatile memristor, memcapacitor and meminductor that exhibit "hysteresis" only in the case of slow changing input. If we wiggle the input rapidly, their bizarre ("pinched") hysteresis loop will become a humble straight line (for example, imagine an inert thermistor).
If we assume that volatile "mem" elements possess hysteresis, we should accept that the ordinary ("not mem") capacitors and inductors possess hysteresis as well. For example, if we drive a capacitor with low frequency AC input current, measure the voltage across it as an output and draw its "IV curve", we will probably see a "hysteresis" loop (I am not sure if it will be "pinched"; please, check it:)
It seems only nonvolatile "mem" elements (i.e., true memory elements) should possess hysteresis since their IV curve does not depend on the input rate? Please, discuss this extremely interesting topic; I would like to know if I am right. I have copied this text from memristor talk. Circuit dreamer ( talk, contribs, email) 09:48, 10 April 2011 (UTC)
Hysteresis is a very general phenomena. It seems that all fields should be treated equally here, not dismissed with "and also's". Certainly, the rest of the article acknowledges this (though the citation's are too sparse), but the introduction should be more universal also.— Preceding unsigned comment added by 146.186.131.40 ( talk • contribs) 19:02, 30 March 2012 (UTC)
The first reference ( http://www.ramehart.com/goniometers/contactangle.htm) has been moved to http://www.ramehart.com/contactangle.htm
I took care of it.
— Preceding
unsigned comment added by
Marvin W. Hile (
talk •
contribs)
14:42, 29 October 2012 (UTC)
In the section on elastic hysteresis, it says, "In the elastic hysteresis of rubber, the area in the centre of a hysteresis loop is the energy dissipated due to material plasticity." How can this be caused by plasticity when there is no permanent deformation? And if this is incorrect, what is the correct name for the property which results in energy dissipation due to internal friction type losses during elastic deformation? 193.52.102.13 ( talk) 18:22, 28 January 2013 (UTC)
I lack the technical expertise to add this topic, but as an amateur I am pretty certain the level of the water table (measured below a nominal ground level datum point) if plotted against the local rainfall will show a rate-dependent hysteresis effect. The water table falls during dry weather and continues to do so for some hours / days after there is significant rain. Similarly it continues to rise for some time after the rain stops. Would someone like to comment on this observation? I realise that there are other factors in play such as air temperature, evaporation, other sources of water and so on. -- BletchleyPark ( talk) 00:10, 2 August 2013 (UTC)
If a thermostat had positive feedback, the temperature would "run away," overheating more and more, or overcooling more and more. Thermostats are an example of negative feedback systems. 129.6.57.132 ( talk) 17:28, 7 November 2013 (UTC)
An IP editor has claimed that the diagram in Hysteresis#Elastic hysteresis is incorrect: "The diagram should be a steep gradient followed by less steep and then steep." Does anyone know if that is true? I found one diagram from a publication that looked like the one in this article, but it is just a schematic. A citation would be useful. RockMagnetist ( talk) 18:00, 11 April 2014 (UTC)
:::That diagram looks like the same one with a different vertical scale. I think the other editor was saying that the curve should have negative curvature at first and then positive curvature - as in
this image.
RockMagnetist (
talk) 14:52, 14 April 2014 (UTC) Sorry, I needed to refresh the page before I could see the new image.
RockMagnetist (
talk)
14:57, 14 April 2014 (UTC)
File:Elastic_Hysteresis.svg does did seem wrong to me. See image posted to right. I placed it ahead of all discussion so it would fit nicely in this section.[User:Guy vandegrift|Guy vandegrift]] (
talk)
15:50, 13 April 2015 (UTC)
Also, I placed the link to this diagram in External Links at the bottom of your article to conform to WP standard practice on sisterlinks. I am not asking you to move the link up to the section on mechanical hysteresis, but won't complain if you do.--
Guy vandegrift (
talk)
18:27, 13 April 2015 (UTC)
--- Guy vandegrift ( talk) 16:53, 14 April 2015 (UTC)
Section 5, Hysteresis in materials, subsection 5.1, Magnetic hysteresis, seems pretty clear to a layman until the end of the second paragraph, reproduced just below:
"...If the magnetic field is now reduced monotonically, M follows a different curve. At zero field strength, the magnetization is offset from the origin by an amount called the remanence. If the H-M relationship is plotted for all strengths of applied magnetic field the result is a hysteresis loop called the main loop. The width of the middle section is twice the coercivity of the material.[16]"
The phrase "...plotted for all strengths of a magnetic field..." probably means for all strengths, both in the original direction and also in the opposite direction. But this is not clear because the previous sentence stops at "...zero field strength..." which in the diagram is the y-axis. The part of the upper curve to the left of the y-axis is not explicitly explained, either in the text or in the diagram. Moreover, even less clear is the lower curve in the diagram which is not mentioned at all, much less explained or labelled, which includes its not having any directional arrows. Wikifan2744 ( talk) 20:20, 20 October 2014 (UTC)
Here is a correction and addition to what I say above. Contrary to what I said, yes, the lower curve is mentioned. But it is not labelled with arrows nor discussed. Further, both the short middle curve and the right side of the upper curve have arrows going in both directions, quite confusing, even to someone who already knows a little bit about the subject.
In addition, earlier in the part of the second paragraph quoted above, it says, "...If the magnetic field is now reduced monotonically, M follows a different curve....." Does that mean actively reduced? If so, what happens if the magnetic field is merely turned off? Which curve is followed in each case? Does the part of the upper curve to the left of the y-axis mean that this "monotonic" reduction includes suddenly reversing the direction of the applied magnetic field? Are the curves the same regardless of how rapidly the magnetic field is changed or reversed or cycled? Under what circumstances does the lower curve come into the process? All of these are matters surely perplexing to a novice; and, as I say above, they are even quite confusing to someone who already knows a little bit about the subject. Wikifan2744 ( talk) 22:49, 20 October 2014 (UTC)
The new lede sentence reads:
I prefer the original lede, but think it should be revised:
The editor claims that the original lede violates gramatical conventions, and I am relatively unsophisticated in such matters. My concern is with readers who have no idea what hysteresis is. One problem, is that the word "current" might lead the reader to think of electrical current. I also think a brief definition is not in order here. Instead, we need more of an explanation. I reverted the recent edit, and the editor reverted. The present lede is acceptable, so I will not revert. But if any editor does not like the lede, please change it. I will continue to watch this page, but will take no action until someone else either edits or adds a comment to this section. I am not always right in such matters, and I know it.-- Guy vandegrift ( talk) 16:01, 13 April 2015 (UTC)
@ Coconutporkpie: You have tagged the lead as confusing, and in your edit summary you say "wording of lead section is vague and does not explain concept in everyday terms". Could you please clarify? I'm not seeing the vagueness, and as for the language, the most difficult word I see in the first paragraph is "dependence". RockMagnetist( talk) 13:54, 15 September 2016 (UTC)
"A Wikipedia article should not be presented on the assumption that the reader is well versed in the topic's field. Introductory language in the lead (and also maybe the initial sections) of the article should be written in plain terms and concepts that can be understood by any literate reader of Wikipedia". — Coconutporkpie ( talk) 00:21, 18 September 2016 (UTC)
The phrase "hysteresis curve" redirects to this page, but the phrase does not exist anywhere in the article. Could someone please add a description, or some kind of correction/explanation if the phrase is somehow discouraged or nonsensical? 72.214.208.2 ( talk) 15:26, 23 March 2017 (UTC)
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Hysteresis is a key concept in the sociology of Pierre Bourdieu. The concept is necessary for Bourdieu because his key concept of habitus implies a certain delay in adapting to changes in the field. For example, if a factory worker loses their job it may take them some time to be retrained in a new technology. Someone who takes up the piano as a teenager is at a disadvantage by comparison who a person who has had lessons since they were a young child. It may be possible to catch up, but in both examples the person is at a disadvantage in the social field because of their previous experience. Source: Cheryl Hardy, Hysteresis, in Michael Grenfell ed. Pierre Bourdieu: Key Concepts (2008). — Preceding unsigned comment added by 70.50.141.229 ( talk) 03:15, 12 November 2017 (UTC)
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The text notes that a latching relay may use a solenoid to hold the relay at a position after power is removed, however many latching relays use a magnet to hold the relay's position after power is removed, then power is used to overcome the relay coil's hysteresis and the magnet holding the relay's position. So the ext is a bit off, many latching relays utilize magnets, not solenoids. SoftwareThing ( talk) 17:37, 30 August 2018 (UTC)
The first sentence in section "Types" ends with a Greek letter. This (exact) letter does not appear anywhere else in the document. It either needs to be altered or removed. I'm not familiar with the physics (or I would fix it myself), but it looks like it should be a capital phi. GregJ77 ( talk) 13:29, 8 May 2019 (UTC)
The lead defines hysteresis simply as system dependence on history. I'm no expert here, but as I read into the topic it seems that hysteresis usually means something much more specific. Morris (2011) points to "two key aspects of hysteresis that are still regarded as characteristic today: “lagging” and rate-independence" - this makes it a far more specific system property that simple dependence on history. Kyle MoJo ( talk) 04:38, 8 April 2020 (UTC)
The first sentence says "Hysteresis is the dependence of the state of a system on its history." and the first sentence of the last paragraph of the intro says "Systems with hysteresis are nonlinear". Those are conflicting statements. Linear systems' state can definitely depend on history. From where I come (control systems) hysteresis is a phenomenon when a system's static characteristics depend on history, no just its dynamic state. Some ambiguity may come from the definition of "state" - for me it's the current, momentary value state. Other fields may have a different point of view, but those two sentences are definitely conflicting. Petar Petrov Donchev ( talk) 06:44, 22 January 2021 (UTC)
Short article that has nothing that can't be included in Hysteresis if it isn't said there already. That is, unless someone has material to substantially expand Hysteretic model with, excluding material related to a specific model that should really be in the article about that model (see the List of models section). Largoplazo ( talk) 21:24, 25 August 2023 (UTC)