Velocity-limited?

Minh Tam

Senior Member
Vietnamese
Hi everyone,
I have a problem with compound adjective. Could you help me with it?

"Back electromotive force is proportional to velocity, and therefore the moving-element characteristic in the flexure-controlled region will be velocity-limited."

flexure-controlled region: Does it mean the region is controlled with flexure?
velocity-limited: Does it mean the moving - element characteristic is controlled with velocity?

Thank for your consideration!
 
  • dojibear

    Senior Member
    English - Northeast US
    Where did you see this text? What is its source? The uses of "back" and "characteristic" seem odd.
     
    Last edited:

    Minh Tam

    Senior Member
    Vietnamese
    Hi dojibear,

    This is the whole paragraph:
    For a typical low-impedance, well-damped vibration exciter driven at constant voltage, the suspension resonance is eliminated owing to the damping effect introduced by the low output impedance of the power amplifier: the back- e.m.f. generated in the moving coil is short-circuited through the amplifier. Back-e.m.f. is proportional to velocity , and therefore the moving-element characteristic in the flexure-controlled region will be velocity-limited and the acceleration-against-frequency characteristic will show a rising slope of 6 dB / octave in this region.

    The text is from a book: Mechanical vibration and shock measurement.
     

    AnythingGoes

    Senior Member
    English - USA (Midwest/Appalachia)
    The flexure-controlled region is the region whose flexure is controlled. The velocity of the moving-element characteristic will be limited.
     

    Minh Tam

    Senior Member
    Vietnamese
    Hi AnythingGoes,

    I found this on the internet:
    "Brain-controlled robots
    CSAIL system enables people to correct robot mistakes using brain signals."

    As far as I know, it means: Robots which are controlled by brain. So I think that I can use analogy here.
     

    AnythingGoes

    Senior Member
    English - USA (Midwest/Appalachia)
    Hi AnythingGoes,

    I found this on the internet:
    "Brain-controlled robots
    CSAIL system enables people to correct robot mistakes using brain signals."

    So I think that I can use analogy here: Robots which are controlled by someone's brain.
    :thumbsup:
     

    Minh Tam

    Senior Member
    Vietnamese
    Hi dojibear,

    My question may be not about the meaning of the sentence, but the way we understand the compound adjective such as: velocity-limited.
     

    Delvo

    Senior Member
    American English
    In general:
    Noun Hyphen Adjective = Adjective Preposition Noun

    So...
    Velocity-limited = Limited by velocity
    Flexure-controlled = Controlled by flexure
     

    Minh Tam

    Senior Member
    Vietnamese
    In general:
    Noun Hyphen Adjective = Adjective Preposition Noun

    So...
    Velocity-limited = Limited by velocity
    Flexure-controlled = Controlled by flexure
    Thank Delvo for your explanation! Now I feel more confident to deal with Noun Hyphen Adjective.
     

    Andygc

    Senior Member
    British English
    To be sure what "flexure-controlled" means requires an understanding of the subject (which I don't have). On the face of it, this means "controlled by flexure", but this seems a questionable meaning in the context of damping vibration. The region "whose flexure is controlled" seems more likely. I suspect that the writer should have written the sentence differently.

    Actually, I know he should have, in that "velocity-limited", coming after the linking verb, should not be hyphenated.
     

    dojibear

    Senior Member
    English - Northeast US
    In general:
    Noun Hyphen Adjective = Adjective Preposition Noun

    So...
    Velocity-limited = Limited by velocity
    Flexure-controlled = Controlled by flexure
    "Velocity-limited" can mean 2 things:
    1) something is limited by the velocity
    2) the velocity of the object is limited

    Similarly, a flexure-controlled region can be:
    1) a region where things are controlled by flexure
    2) a region in which the flexure of things is controlled

    Since the two meanings are opposite, the hyphenated word is ambiguous. The context may eliminate one meaning, to an expert reader.
     

    dojibear

    Senior Member
    English - Northeast US
    I don't think you need much expertise to recognize, from even the short extract quoted, that the first of each of your pairs of meanings applies here.
    Do you mean the short extract in post #1 or in post #3?

    I disagree. The readers needs a knowledge of electromagnetics. I didn't understand "region of flexure" or "limiting the velocity of a characteristic", so I could not eliminate either meaning in either pair. I have a college degree in engineering, but I do not know what those terms mean.

    OP is asking about all cases of "noun hyphen adjective", not just his example. My "ambiguous" comment refers to all cases.
     

    Edinburgher

    Senior Member
    German/English bilingual
    Do you mean the short extract in post #1 or in post #3?
    I did mean #1, but #3 is clearer. The linked document itself clarifies that the "region" is a section of a graph, and the "characteristic" is a feature in the graph.

    Mechanical engineering isn't my field, but I do know what back-e.m.f. is. Perhaps that qualifies me as an "expert reader" and thus invalidates my comment. :)

    Fair enough about the more general case.
     
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