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1500 questions
13
votes
7 answers
Wind farms that wind up in the wind, and then unwind producing energy when the wind is still
Given the difficulty of producing energy for a region when the wind isn't blowing, why is it not possible to have half of each wind farm producing energy directly, and the other half working to lift a weight, that then descends and produces energy…
apg
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13
votes
2 answers
How does a multimeter protect itself from high voltages?
I have used a cheap multimeter to measure voltages in simple DC circuits, but I have seen pictures of them plugged straight into the mains and used to measure various home-built generators.
Why doesn't the higher voltage fry the multimeter, and also…
jhabbott
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13
votes
3 answers
Measuring longer distances with high accuracy
I am involved right now in the fabrication of steel structures on the order of 5-50 feet long. Presently, we measure these structures with garden variety commercial tape measures. Most of the time, we work to a tolerance of about +/-1/16" and don't…
Ethan48
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13
votes
4 answers
How can I tell if I got counterfeit aluminum?
I recently received an order of extruded aluminum strip 3/32" thick that supposed to be 6061 hardened to specification ASTM B221. However, when we tried to bend it, it broke and the interior looked like cast zinc coated with aluminum. Is 6061…
Wallace Park
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13
votes
1 answer
How does a (pulley based) continuous variable transmission (CVT) work?
How does the (pulley based) CVT achieve the following?
no requirement for a clutch
fuel economy
smooth gear transition
NMech
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13
votes
2 answers
What would "wired houses" refer to in 1928?
I read this today:
Variety (November 21, 1928) wrote: "Not the first animated cartoon to be synchronized with sound effects, but the first to attract favorable attention. This one represents a high order of cartoon ingenuity, cleverly combined with…
Willamson
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13
votes
2 answers
Do "analog FPGAs" exist?
I am thinking on analog circuits, whose circuit design could be read (or, at least, significantly altered) from software. Do they already exist?
peterh
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13
votes
2 answers
How do you ensure physical network interfaces always get the same interface name across reboots on an embedded Linux system?
For an embedded Linux system, if I have two or more network interfaces, how do I ensure that they always get the same interface names every boot
In other words, I want, for example, eth0 to always map to one physical Ethernet port, eth1 to the next,…
Patrick
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13
votes
1 answer
What are left justified and right justified ADC results?
The TI MSP430F20XX series has a 12-bit internal ADC output, which is right-justified.
What is the difference between a left-justified output and a right-justified output? What are their pros and cons?
prasad
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13
votes
4 answers
How much clearance does a car need when turning a corner?
I am contemplating buying a new car. However, the approach to the underground garage in my apartment has a 90 degree frustrating turn. Given the dimensions of the approach and car, what is the max turn circle for the car to fit the garage and…
Misha
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13
votes
3 answers
Do I need to worry about galvanic corrosion when inserting a steel bar through aluminium?
My design uses a round steel bar inserted through a hole in an aluminium component with a tight fit (no movement). The operating environment is dry, 20-40°C.
Do I need to worry about galvanic corrosion, and if so how long will this last before…
jhabbott
- 5,990
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13
votes
3 answers
Which turbulence models are suitable for CFD analysis on a streamlined vehicle body?
Many commercial and open-source CFD codes implement several closure methods for the non-linear convective acceleration term of the Reynolds-averaged Navier-Stokes (RANS) equations. Common methods (also known as turbulence models)…
Paul Gessler
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13
votes
6 answers
Distance sensors with accuracy of 1 mm?
I am making a device for measurements. I would like to measure the distance within accuracy of 1 mm. Range could be 2 cm to 15 cm . I looked at Proximity Sensors but the readings displayed by these sensors are not steady.
I wish to measure the…
JustCurious
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13
votes
2 answers
How do I solve an optimal control problem where the dynamics depend on some function of the state?
A typical optimal control problem with state $x(t)$ and control $y(t)$ can be expressed as $$\max_{x(t), y(t)} \int_0^{t_1} f(t,x(t), y(t)) dt$$ subject to $x'(t)= g(t, x(t), y(t))$ and boundary conditions for $x(t)$.
I want to solve a problem that…
Daniel Wills
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13
votes
4 answers
Easy nonlinear model for large deformation of a beam
I have a beam subject to twisting and/or bending forces as well as linear compression force along its main axis. It is modelled as an isotropic beam, but if anisotropic is not too far off then that's okay too. The beam is capable of large…
imacube
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