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1500 questions
5
votes
1 answer
Specification of hole design tolerance
Suppose the fit for a rod and a hole in a gear is supposed to be free running and the fit is 3mm H9/d9. For the specification of the hole for the manufacturing of the gear, is "3mm H9" already adequate since d9 only refers to the shaft tolerance…
WKleinberg
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Choosing of repeating variables in Buckingham's Pi theorem
What are the criteria for choosing repeating variables in Buckingham's Pi theorem in dimensional analysis? In many problems, it's solved by taking D,V,H (Diameter, Velocity, Height) as repeating variables. Why do they take the above variables as…
salih kallai
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5
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Square shaped position error
I got a position error measured by a linear encoder like in the picture below.
Could anyone explain some possible reasons for this kind of shape to occur in control theory?
My system looks like table with four legs.
The four legs move up and down…
KKS
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5
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1 answer
Circular motion and Car's Tire Angle
I'm trying to figure out what angle to turn the front tires of my small robotic car (about a foot in length) so that it moves in a circle (on level ground) of radius $r$ (will be accommodating circles of different radii). In addition to being able…
S.C.
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Could linear bearings bear axial load?
With linear bearings, could they be used to join one rod with another to form a cross-junction and rotate with around a 0.3N-mm torque? Suppose the rods are fairly thin, eg, 5mm in diameter. That is, could linear bearings bear a radial load? Would…
Kar
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5
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1 answer
How to determine if mass transfer convection is natural or forced?
I know that forced convection requires some external bulk flow, but is there an equation to determine which form of Convection is dominant? I looked around and found the Richardson number $\mathrm{Ri}=\frac{\mathrm{Gr}}{\mathrm{Re}^2}$ but I don't…
user4785
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5
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2 answers
How effectively would a typical liquid CPU cooler cool a 15"x15"x1/8" sheet of aluminum?
I'm curious about whether a typical liquid CPU cooler (like, e.g., this Corsair H60) would be able to effectively cool a square sheet of aluminum with 15" sides and a thickness of 1/8".
I'm not even sure how to properly formulate the question so…
Dennis
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5
votes
3 answers
What are safe locations for openings in reinforced concrete beams?
I had an argument with a friend about the safe location for openings in reinforced concrete beams. I've chosen position 1, a little above reinforcement steel, as at this location, the beam is subjected to tension in the lower fibers which is…
cmoha
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5
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1 answer
Baffle vs Bottom Temperature Measurement/Control
In an industrial jacketed reactor, we have two temperature probes:
one on a baffle the extends down about to the 50% fill line
one built into reactor, very close to the bottom valve.
When is it more reliable and practical to use one location…
tralston
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5
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3 answers
Questions about the level flight lift equation
In level unaccelerated flight we have relation
$$
W=L=\frac{1}{2}\rho\cdot V_{stall}^2\cdot S\cdot C_{l,max}
$$
taken from book Daniel P Raymer "Aircraft Design: A Conceptual Approach" equation (5.5) at page 85.
The question is: why does this…
p.pensopositivo
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5
votes
1 answer
System Identification 1-d altitude control
One dimensional altitude control of a hovercraft. The model's dynamic equations that I came up with are, I treat the hover craft as a rigid particle and my goal is to have it hover at or reach a certain desired height.
$$F = ma$$
$$X(t) - mg =…
user1084113
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5
votes
4 answers
Why can't proportional gain alone, reduce the error to zero?
I was told that the proportional gain alone cannot the drive the error signal to zero in a feedback loop. Why is that? If there is a tiny error, there will be a tiny or larger (depending on the number of proportional gain) correction, so why won't…
ergon
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1 answer
How can we derived the equivalent Lumped Mass Model for irregular building and how to calculate the errors?
Intuitively, building can be represented as a lumped mass model ( the taller the merrier!):
Assuming a building is a lumped mass cantilever column also makes the global stability checks easier because building codes often assume building structure…
Graviton
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5
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1 answer
Calculate Forces on a Flywheel
I am working on a flywheel currently, and I was wondering what is the force needed to recenter the flywheel when it is spinning and it is nudged slightly off axis? Is it related to gyroscopic precession?
Sean
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5
votes
1 answer
ASCE 7-10 Wind Loading with roof overhangs
A textbook is attempting to convince me that the following figure:
Represents the generic zones for a Case B wind loading including roof overhangs based on the ASCE 7-10 Chapter 28, Part 2 (Enclosed Simple Diaphragm Low-Rise Buildings) procedure.…
user32882
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