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1500 questions
9
votes
3 answers
Would a PE-pipe filled with concrete make a good pillar?
An idea that keeps popping up in my head, that I don't know enough structural/civil engineering to know if it's good from a technical point of view.
Take a piece of polyethelene (PE) piping, fill it with concrete, let the concrete bind. My…
mart
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9
votes
0 answers
What type of ultrasonic transducer would be suitable for ultrasonic welding?
Project background:
I am working on a project where i need to weld plastic using ultrasonic transducers.
Problem:
Since I'm still learning engineering, I have a hard time figuring out what all the factors are in order to choose the right…
vaid
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9
votes
10 answers
How can "mpg" be high under low engine load?
Let's say a car at 60 mph requires roughly 20 hp to maintain its speed (i.e., to overcome rolling resistance and drag).
If this car makes 240 hp and gets about 34 mpg (not too unrealistic), how is it getting 34 mpg if the engine is only at 0.05…
NumberJuan
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9
votes
1 answer
Sensors / processing algorithms to emulate a human's sense of smell
A lot of research has been devoted to creating electrical devices that emulate biological sensors, including:
Visual: Cameras, color/light intensity sensors
Auditory: Microphones, ultrasonic sensors
Tactile: Pressure sensors, temperature…
Paul
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9
votes
4 answers
What's a professional way of tracking design history in plant engineering?
If you look at the design documentation in our projects (Biogas and waste-to-energy plants), you find out what we plan to build but not what other options were considered and why they were discarded. This information rests only in the engineers…
mart
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9
votes
1 answer
Thrust distribution of engine
I am studying the thrust distribution of jet engines.
But I'm now a bit confused.
In Rolls-Royce's "The Jet Engine" book,
http://aeromodelbasic.blogspot.com/2012/05/thrust-distribution-distribution-of.html
At the start of the cycle, air is induced…
Jono
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9
votes
2 answers
How can a knife cut through butter?
How does anything actually cut anything, since we all know stuff is made up of atoms and molecules, which can't be touched together (It Requires Binding Energy). So how come we see things all around us being cut so easily?
user16364
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9
votes
2 answers
What causes friction in magnetic bearings?
Magnetic bearings work by levitating a rotating shaft so that it is not in contact with its supports. This greatly reduces the friction of the system.
In all of the literature that I have seen on magnetic bearings, the bearings are described as "low…
hazzey
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9
votes
5 answers
How can one calculate the change in heat energy when the specific heat varies with temperature?
Many materials have a specific heat which varies with temperature, especially as the temperature change grows large. How does one calculate the heat energy that an object receives in this case? Can we simply use the specific heat capacity at the…
Max Ning
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9
votes
1 answer
"Sliding door" - is top weight bearing more efficient?
I'm an artist building a project which one could think of as a "sliding door" – a very narrow panel running on grooved wheels riding in tracks at top and bottom. It will be motorized and driven by a stepper motor, timing belt and pulleys. I will…
spring
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9
votes
1 answer
Differences between 2D hydrological modelling programs eg. HECRAS 5.0 (2D), TUFLOW, MIKE Flood
Just wondering what the difference is between 2D flood modelling programs. I am primarily considering whether HECRAS 5.0 (2D - currently in Beta) would be an acceptable alternative for simple 2D flood depth and velocity studies when compared to…
octopi
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9
votes
3 answers
Bonding Semiconductors to PCB
I'm trying to bond semiconductor samples (Si and Ge) area ~1-2cm^2 to
fiberglass printed circuit board (PCB)
We use West system marine epoxy for other things. 105 resin 209 hardener (long cure time.)
So that's what I used. (mixed at standard ratio)…
George Herold
- 437
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9
votes
1 answer
What is the benefit of additional planetary gears?
A planetary gear is a gear that rotates not around an axle but around another gear known as a sun gear, or star gear. I have designed prototype systems in the past that used a single planetary gear rotating around a rotating gear. However since then…
Sam Weston
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9
votes
3 answers
Mechanism of gear rotation
Is the smaller gear (pinion) always mounted to the input shaft when meshed with a bigger gear that is mounted on the output shaft? Are there places where the bigger gear drives the smaller gear?
Debanshu Thakur
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9
votes
1 answer
Calculate force to lift piston from a given closing pressure
I am trying to calculate the force required to close the valve on an annular blow-out preventer. A rubber ring (called a packing unit) closes around the pipe when a force is applied from underneath, as shown here:
The actual valve has the hydraulic…
Blue7
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