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1500 questions
8
votes
1 answer
Degassing silicone solution with negative pressure
I am planning to use polydimethylsiloxane (PDMS) to create a phantom for mimicking tissue for imaging. For this, I plan on using SYLGARD® 184, which is a viscous liquid. When adding other components to it, air bubbles will be introduced.
I have…
Nazar
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8
votes
3 answers
Why raised face for mating parts?
In designing mechanical parts in an assembly, sometimes the mating surfaces are raised faces. I've been told it's to provide a better seal. However, for piping (flanges), it seems to be the consensus that a raised face flange does not provide any…
tralston
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8
votes
5 answers
Why do some diesel engines run on diesel fuel and others on fuel oil?
Trucks and smaller vehicles with diesel engines run on diesel fuel which looks more or less like kerosene - less flammable than gasoline, low viscosity liquid. However larger diesel engines like this 120 thousand horsepower marine engine have more…
sharptooth
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8
votes
1 answer
Best way to send a signal in a very low frequency (250Hz)?
I am a programmer facing an electronic question, so I thought here is the place to ask!
I have a magnetic field sensor which provides me with magnetic field values (XYZ axis) 250 times a second.
An electronic circuit with a programmable…
rubmz
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8
votes
3 answers
Protecting device from microwaves in microwave oven.. but allowing Bluetooth?
I am building a device that needs to be inside of a microwave oven but somehow needs to communicate with another device outside of the microwave.
How can I reflect microwaves so they don't come into contact with the electronics in the device, while…
Tyler
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8
votes
1 answer
Can nuts safely be removed from bolts where the threads have been intentionally damaged?
On old bridge plans I have occasionally seen a note to "burr threads after installation". This was done to keep the nuts of bolted connection from loosening all the way and falling off of the bolt.
An example of this practice can be seen in this…
hazzey
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8
votes
2 answers
How does the shape of CPU/GPU fan blades affect their performance and loudness?
I need to replace the fan on my graphics card. The original fan is exactly like this one but there is another fan that seems to be a new revision of the same model number from the same manufacturer (NNTG vs. NNTM). The main difference seems to be…
MoonSweep
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8
votes
5 answers
Knowing how many times the rear wheels have rotated, and the angle of the front wheels at every time interval, how do I find the location of a car?
I'm making a robot for the Sparkfun AVC. I was curious if I could use only the knowledge about
How the car is being steered at every time interval,
How many times the wheels have rotated,
to get a general sense of where the car is. I would use…
Daniel Sims
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8
votes
3 answers
Calculating moment of inertia for a hollow discontinuous circle?
This is a pretty simple problem, but I'm just not sure how to go about it. I want to find the moment of inertia of a discontinuous hollow circle. But since the shape is so irregular, I'm not sure how to go about solving for it. I've posted the shape…
tempestwing0101
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8
votes
2 answers
System Dynamics Modeling
I am trying to model this system but am having difficulties in setting up the equations of motion. This is a simplified model of a motorcycle suspension system, where P is the ground in the image below. In addition, the variable $u$ is the input to…
Josh Pilipovsky
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8
votes
1 answer
Why build a cell lattice tower with square cross-section instead of triangular cross-section?
First, a neat image from Wikipedia
Here the cell tower has three vertical (or maybe slightly inclined to the inside) thicker pipes which are located at angles of a triangle and those three thicker pipes are interconnected with numerous thinner…
sharptooth
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8
votes
4 answers
Could house fires be prevented by increasing dryer vent speed?
In the US, clothes dryers are one of the leading causes of house fires:
In 1998, CPSC estimates that there were approximately 15,600 clothes dryer fires resulting in 20 deaths, 370 injuries and $75.4 million in property damage.
Or more recent…
hazzey
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8
votes
2 answers
How Can I Determine Multiple Discharges from a Pipe Network? (Knowing the Inlet Conditions)
I have little/no experience with pipe networks and have been searching for a methodology to calculate the discharge from multiple outlets of an oil pipe network with a single inlet. As far as i can tell I have too many unknowns to use something like…
Petrichor
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8
votes
1 answer
Why is this construction site pouring gravel over a wire mesh, and then covering it with dirt?
My office is afforded a prime view of a construction project where the workers are currently covering the leveled ground in a wire mesh, raking gravel across the entire mesh, and then covering that gravel layer in another layer of dirt.
What is the…
TylerH
- 187
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8
votes
5 answers
Height limits of brick and mortar tower?
What are the factors limiting the height of a "tower" made of typical fired brick and mortar?
By "tower", I mean a structure whos point is to be tall, and can support a human standing on or near its top. I'm interested in the self-supporting…
Olin Lathrop
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