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#20 -- A Question of Stability (Revised)

DrD

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    Mechanics Corner
    A Journal of Applied Mechanics and Mathematics by DrD, #20
    © Machinery Dynamics Research, 2015


A Question of Stability

Introduction

    The word stability in its several forms is widely used in nontechnical communication. A person whose life it highly consistent from day to day is said to have a stable life. When the political situation in a particular area appears to be unlikely to change, it is said to be stable. A person who is well balanced and unlikely to be easily provoked to anger is said to be a stable person. When the medical condition of a sick or injured person ceases to get worse, the person is said to be stabilized. A company on the verge of bankruptcy is said to be an unstable company. But what does the word stability mean in a technical context? Each of the foregoing examples hints at the technical meaning without really being explicit about it.

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A factor g = accel of gravity was missing in the potential energy expression. That is now corrected.
    
 
 

 

Stability.pdf


saurabhjain and Noble Edward like this


14 Comments


Enjoyed reading your paper, nicely done indeed! I could relate to many principles articulated in the paper in my field, in particular the challenge of identifying neutrally stable states in a system - though I am no mechanical engineer, skillful art of contriving something is what we humans call 'engineering' after all, is it not? :) 

Thanks DrD.

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I am pleased that you found the paper interesting and useful. I wish that you had told us what your own field is, so that we could see where there is a non-ME application of these ideas.

DrD

Noble Edward likes this

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My bad DrD, I should have laid out the premise before I referenced it in my earlier response! I am a software engineer. I architect and code RTC (Real-Time Computing) systems for living; State Machines are integral part of such systems. For brevity’s sake shown below is just a section of one such system I am designing. The algorithm shown here transitions to various states, S14 to S20, based on a variety of triggers, constraints, conditions and feedback, such that it eventually transitions to a goal (Sna stable state, not shown in the picture) with enough data (steering, torque etc.), to maneuver or stall a drive unit. States S15, S19, S18 & S20 are persistently unstable states, while states S14, S16S17 are Neutrally Stable, but within a lease - a time-slice within which that state must make an informed decision before a preempt flag is raised to terminate the lease, at which point the state goes out of "domain of stability" and becomes unstable, consequently hunts (transitions) to stabilize itself elsewhere.

Hope I didn’t make my point dreary and complex in an attempt explaining how ideas transcend faculties – well, that’s what my friends complain about me! LOL

 

 

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Anyways, I passionately believe that inventions flourish when faculty compartmentalization is annihilated, and synergy is desired – that should explain my fascination towards mechanical engineering... :)

 

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This is a very important topic, more important than most will realize while still in school. I hope that it will be widely read.

DrD

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Juaniles, I'm sorry to have to tell you that I do not speak Spanish, and therefore do not understand your question. If you can put it in English, perhaps I will be able to answer it.

DrD

Juaniles, I'm sorry to have to tell you that I do not speak Spanish, and therefore do not understand your question. If you can put it in English, perhaps I will be able to answer it.

DrD

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