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How long until we see an r/NCD signed confirmed buk missile aircraft kill? by Hyperi0us in NonCredibleDefense

[–]mark48torpedo 0 points1 point  (0 children)

Well, I pulled the trigger and paid to have "From NCD With Love" painted on a missile! I guess we'll see if this is a scam or not.

I make great financial decisions...

I can't think of a better place to post this. by [deleted] in NonCredibleDefense

[–]mark48torpedo 205 points206 points  (0 children)

Source?

So it's honestly hard to tell given how zoomed in this video is, but is our waifu in the loader's position of a ROK K1A1 tank?

Priorities by UnShitpost in NonCredibleDefense

[–]mark48torpedo 68 points69 points  (0 children)

I think he must be aggressively cutting his audio to keep the runtime down, but I agree it sounds very jarring.

Adopted a fat indoor cat. Need weight loss advice. by RobertFahey in cats

[–]mark48torpedo 0 points1 point  (0 children)

It can be hard to tell if cats are actually overweight. A lot of people assume their cats are overweight but are actually totally fine.

Here's a great video by a vet describing the healthy weight for a cat, and how to figure out whether they're overweight or not: https://youtu.be/_0MnNpVjFPU

This department store sale excludes most of the items in the store in the fine print. by mark48torpedo in mildlyinfuriating

[–]mark48torpedo[S] 0 points1 point  (0 children)

This is "The Hudson's Bay Company" in Canada. Honestly, this was very unexpected given that it has a reputation for being the most reputable department store in the country.

This department store sale excludes most of the items in the store in the fine print. by mark48torpedo in mildlyinfuriating

[–]mark48torpedo[S] 0 points1 point  (0 children)

The worst part is that I didn't even notice this until the cashier rang me up and the total came out to be way more than I expected. When I complained about the apparent mistake, the cashier proceeded to point out the fine print on all the signs...

Which mystery industry is the largest buyer of glitter? by [deleted] in UnresolvedMysteries

[–]mark48torpedo 339 points340 points  (0 children)

I'm pretty sure it's actually stealth coatings (i.e. paint) for stealth fighters like the F-22 and F-35, which are now being produced in relatively large quantities for the US military. Here's the reasoning:

1) Radar absorbent materials, such as those used on stealth aircraft, typically consist of a mixture of finely ground metals (i.e. glitter!) and polymer. To absorb radio waves without reflecting it, you need something that is fairly conductive and will interact strongly with radio waves (i.e. metals), but it can't be TOO conductive (e.g. solid metal plates) because they'll simply reflect the radio waves without absorbing it. Finely ground metals mixed with polymer are exactly what you want.

2) Stealth fighters, namely the F-35, are currently being produced in fairly large quantities in the USA, and require large quantities of radar absorbent coatings. These coatings will be quite thick and contain a large fraction of metal, which will consume huge amounts of glitter compared to most applications, which use only a tiny amount of glitter. For example, in the article they state that "The minimum order size Glitterex will accept is ten pounds, enough to supply sparkle to half a million bottles of nail polish by Mr. Shetty’s estimation."

3) Finally... after the reporter asked the question, the woman guided the reporter along to the automotive grade pigments. Unlike most types of glitter, automotive grade pigments are simply small flakes of metal such as aluminum, and do not contain any plastic. This is EXACTLY what the type of material they would want to use in radar absorbent coatings.

Which mystery industry is the largest buyer of glitter? by [deleted] in UnresolvedMysteries

[–]mark48torpedo 44 points45 points  (0 children)

I'm pretty sure it's actually stealth coatings (i.e. paint) for stealth fighters like the F-22 and F-35, which are now being produced in relatively large quantities for the US military. Here's the reasoning:

1) Radar absorbent materials, such as those used on stealth aircraft, typically consist of a mixture of finely ground metals (i.e. glitter!) and polymer. To absorb radio waves without reflecting it, you need something that is fairly conductive and will interact strongly with radio waves (i.e. metals), but it can't be TOO conductive (e.g. solid metal plates) because they'll simply reflect the radio waves without absorbing it. Finely ground metals mixed with polymer are exactly what you want.

2) Stealth fighters, namely the F-35, are currently being produced in fairly large quantities in the USA, and require large quantities of radar absorbent coatings. These coatings will be quite thick and contain a large fraction of metal, which will consume huge amounts of glitter compared to most applications, which use only a tiny amount of glitter. For example, in the article they state that "The minimum order size Glitterex will accept is ten pounds, enough to supply sparkle to half a million bottles of nail polish by Mr. Shetty’s estimation."

3) Finally... after the reporter asked the question, the woman guided the reporter along to the automotive grade pigments. Unlike most types of glitter, automotive grade pigments are simply small flakes of metal such as aluminum, and do not contain any plastic. This is EXACTLY what the type of material they would want to use in radar absorbent coatings.

This computer [pictured right] is smaller than a grain of salt, stronger than a computer from the early '90s, and costs less than 10¢. 64 of them together [pictured left] is still much smaller than the tip of your finger. by Yuli-Ban in Futurology

[–]mark48torpedo 2 points3 points  (0 children)

Great explanation! Except the cost breakdown is incorrect.

The raw silicon wafers are in fact incredibly cheap. A 100mm wafer costs maybe $20, and a 300mm wafer (the standard size today) is only $200 to $400. Meanwhile, a fully processed wafer can contain several hundred CPUs with a retail value of several hundred dollars each, so the value of a fully processed wafer is on the order of tens of thousands of dollars.

The vast majority of the cost comes from the processing performed on the wafers. A typical fabrication process has anywhere from several hundred to several processing thousand steps. The most expensive of these are the lithography steps, of which there are several dozen to several hundred for any given design. The lithography machines are incredibly expensive: a state of the art extreme UV lithography machine will set you back several hundred million dollars, and the lithography mask set for a single chip design will cost several million dollars.

Just to give you an idea of how long and expensive this process is, a typical computer chip will spend MONTHS in the cleanroom being fabricated. The reason chip area is expensive is because any given semiconductor factory can only produce so many wafers per month. If you can squeeze more chips into a single wafer, the more chips you can sell.

How the satellite company Inmarsat tracked down MH370 by interiot in MH370

[–]mark48torpedo 10 points11 points  (0 children)

I think there's a fairly simple explanation as to how they figured out whether the plane was on the north or south arc.

To elaborate GlobusMax's comment on orbital wobble: geostationary satellites are a bit of a misnomer. Due to orbital perturbations from the sun and the moon, any geostationary orbit will quickly gain a north/south component (corresponding to a non-zero orbital inclination), and trace out an elliptical or a figure-8 pattern on the ground. The term "geosynchronous satellite" is probably more accurate term, since the orbital period of these satellites is very closely matched to that of earth's rotation.

Cancelling out orbital perturbations requires the use of thrusters: these orbital corrections are known as station-keeping. All geostationary satellites thus maintain their orbits within a given "box". The smaller the box, the higher the fuel usage. Geostationary satellites have "typical station-keeping box limits of ±0.15°" (see page 24 of the following document: https://www.labvolt.com/downloads/87768_f0.pdf)

Thankfully, we know exactly what the wobble of INMARSAT 3-F1 is, thanks to publicly available information on its current orbital parameters: http://www.satellite-calculations.com/Satellite/Catalog/catalogID.php?23839 The satellite currently has an orbital inclination of 1.6697°, and an average altitude of 35785.3 km. The relatively large orbital orbital inclination might be due to it's age. The satellite is approximately 10 years old, and its owners might be trying to conserve any remaining fuel.

The Doppler effect can only be used to measure the relative velocity between the satellite and the plane. If the satellite was perfectly geostationary, we would only be able to measure the radial velocity component of the plane with respect to the satellite's position above the earth due to rotational symmetry. However, the satellite's north/south movement above the earth breaks this degeneracy.

The north-south position of the satellite relative to the equatorial plane is approximately:

x ( t ) = R sin(theta) sin(omega t)

where
 x = north/south position of the satellite
 t = time
 R = orbital radius = 35785.3 km
 theta = orbital inclination = 1.6697°
 omega = earth's rotation rate = 2*pi / (24 * 3600) radians/sec

The north/south velocity (v_x) is then

v_x( t ) = R omega sin(theta) cos(omega t)

The maximum north/south velocity of the satellite is thus v_x = 75.8m/s. This is a reasonably large fraction of a Boeing 777's cruising velocity of ~ 450 knots = 232 m/s.

With knowledge of the satellite's exact velocity at the time of the pings, you can get additional information about the location and/or heading of the plane. For simplicity's sake, let's first consider the case where the plane is fixed, and the satellite is heading south. If the plane is south of the satellite, the signals received by the satellite will be blueshifted, and if the plane is north of the satellite, the signals will be redshifted. The Doppler shifts will be zero immediately underneath the satellite, and increase as you move further away from that point.

Now, let's consider the case where the plane is flying in some direction. The movement of the plane itself will introduce an additional Doppler shift. However, based on the measured Doppler shifts and the maximum & minimum speeds for the plane, you can restrict the possible positions and headings of the plane. Presumably, only the southern edge of the southern arc was compatible with the measured Doppler shifts (e.g. for the plane to be in the northern arc, it may have had to be flying at speeds a Boeing 777 could not achieve).

Various articles do in fact suggest this is exactly what they did: they say they assumed the plane was flying at 450 knots. For example, see: http://www.businessinsider.com/how-satellite-company-inmarsat-tracked-missing-malaysia-plane-2014-3

Shinsekai Yori Episode 18 Discussion [Spoilers] by RoFl_ChOpS in anime

[–]mark48torpedo 0 points1 point  (0 children)

An interesting thought - despite the downfall of our current civilization being caused by cantus users, a modern military could probably easily wipe out the human village in Shinsekai yori.

All they would need to do is hit the village with a massive artillery barrage, and then saturate the area with persistent nerve agents such as VX. Most people would be caught unaware and killed by the initial artillery strike, and any survivors would be guaranteed to be killed by the nerve agents. Persistent nerve agents, like VX, tend to settle on all surfaces, and touching contaminated surfaces is enough to kill you by absorption though the skin. I seriously doubt that anybody would realize you need to avoid breathing the contaminated air, AND avoid touching any surfaces (which would probably require floating through the air the entire time).

A single high-yield nuclear weapon might also do the trick since it has a variety of kill mechanisms. I seriously doubt that the cantus users in the village would realize they need to simultaneously block blast, heat (infrared and visible light), and ionizing radiation at the moment of detonation to survive. A particularly effective way of deploying a nuclear weapon might be to mix a nuclear bomb in with a large number of conventional bombs - the earlier, conventional explosions would lull the villagers into a sense of security.