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1500 questions
7
votes
2 answers
Design of a Four-Bar Infinity Coupler Linkage
How can I control a Four-Bar Infinity Coupler such that it does not accidentally become a Paralellogram Linkage? It seems to me that, when the bars are all horizontal, gravity could change the movement of the green driven…
skibulk
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7
votes
5 answers
How to determine whether plastic is ABS or Polypropylene?
I have a pump that I want to use to pump a solvent. It is hard black plastic so I'm pretty confident it is either ABS or polypropylene (it wasn't expensive enough to be some more exotic plastic).
My solvent will rapidly dissolve ABS but it will work…
ericksonla
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7
votes
7 answers
Why do manufacturers still make aluminum kitchen utensils?
I noticed many kitchen utensils or stand mixer attachments are made with injected aluminum. Aluminum (~\$20/kg) is usually more expensive than stainless steel (~\$10/kg) and is not compatible with dishwashers.
For instance, I have a peeler made…
nowox
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7
votes
2 answers
Material Properties: Does bending reduce iron rebar's strength?
I'm reading an introduction to structural engineering book and there's a fundamental concept I'm trying to relate to real life:
In construction, we regularly bend iron rebar into a variety of shapes and rebar stays locked in whatever bendy shape we…
AlfaZulu
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7
votes
1 answer
What is the equivalent moment of inertia of a two-pivot pendulum?
I am working on a system that consists of a hanging-pendulum thrust balance with two pivot points, one in the front and one in the back There is a heavy weight applied in the front. I can change the position of the center of gravity by applying…
idontexist
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7
votes
2 answers
Could magnetic levitation transportation systems become a commonplace technology?
Magnetic levitation systems of transportation such as trains seem to be commonplace in early 2000's science fiction, and while some systems exist currently, they aren't exactly common.
It seems to me that this technology has grown unpopular (or at…
Sam Weston
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7
votes
1 answer
What is the unbraced length of a pile in soil?
When analyzing a pile or drilled shaft as a beam-column, how do you determine the unbraced length of the portion that is in the ground? Typically, the braced points on a beam or column are well defined, e.g. there are connections at discrete…
hazzey
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7
votes
4 answers
Charging a smartphone battery while using it
While this question pertains to smartphone , it is being asked from purely an electrical engineering view (My electrical knowledge is very basic)
Trying to understand if charging a cell phone and using it is recommended or not, I came across this…
beeshyams
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7
votes
3 answers
What do the zeros of the transfer function tell you about a system?
I come from a mathematics background and I'm familiar with laplace transforms in-as-far-as they provide an algebraic method to solve ordinary differential equations.
So, when I read about transfer functions, I can clearly see the one-to-one…
Paul
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7
votes
3 answers
Compound gear system ratio
This might be a stupid question, but I'm new to mechanics, so please bear with me. Suppose I have a compound gearing system defined in the image below (not to scale).
The green gear is the driving gear, and the blue gear is a compound gear.…
Tom
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7
votes
2 answers
Heating circuit: Galvanized steel with press fitting vs welded steel pipes
What are the downsides for galvanized steel pipes + press fittings vs. welded steel pipes in a heating application? Diameter would be DN25/1".
Background: The customer specifies only steel, only welded connections for heating pipes starting at this…
mart
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7
votes
1 answer
Calculate effort to raise hinged lever with distributed load
My father-in-law would like to install a hinged stair system in his garage that allows him comfortable access to his attic space.
He wants the stairs to swing up flush with the ceiling when not in use, and then to easily swing down when he needs it,…
alfreema
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7
votes
1 answer
Are smaller heat-pumps more efficient?
I was a doing a placement at a company, and they were designing a new heat pump. I was told the more compact you can make a heat-pump, the better it is for efficiency, and they mentioned something about this was because the power density was…
dezza3192
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7
votes
4 answers
Ways to reduce turbulence in internal flows
Often it's desirable to reduce the turbulence level in an internal flow without changing the Reynolds number or fluid. This could be measured by the turbulence intensity, though other measures might be better in different circumstances. I haven't…
Ben Trettel
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7
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1 answer
Modeling Transient Heat Transfer between two 1-D materials
I have been working on creating a 1-D model of a material with a layer of heat resistant material stuck to it. For this I have been trying to use the implicit finite-differential method. The equations are as follows:
$$
\dot{E}_{in} - \dot{E}_{out}…
chap178
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