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gunrunnerhell:

"Dead Hand"

Not my usual firearm post but something weapon related. Dead Hand is a nuclear control system used by the Russians as a deterrence. The system detects a combination of radioactive, seismologic, pressure and light variations to determine if a nuclear strike on Russian soil has occurred. This means that even if all of Russia’s chain of command were killed in a nuclear strike, Dead Hand would respond by launching most if not all of the Russians nuclear ICBM’s at preprogrammed targets.

Dead Hand is supposedly only activated during a potential crisis, possibly to avoid accidental launches if a Russian nuke were to explode by accident. Dead Hand is said to still be in use and receiving modern system upgrades. However, the exact nature of Dead Hand is not known. There is debate whether it is a fully autonomous system or if it does require at least 1 surviving person to issue the final launch command once all parameters have been met.

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fuckyeahfluiddynamics:

In the dark of the ocean, some animals have evolved to use bioluminescence as a defense. In the animation above, an ostracod, one of the tiny crustaceans seen flitting near the top of the tank, has just been swallowed by a cardinal fish. When threatened, the ostracod ejects two chemicals, luciferin and luciferase, which, when combined, emit light. Because the glow would draw undesirable attention to the cardinal fish, it spits out the ostracod and the glowing liquid and flees. Check out the full video clip over at BBC News. Other crustaceans, including several species of shrimp, also spit out bioluminescent fluids defensively. (Image credit: BBC, source video; via @amyleerobinson)

fuckyeahfluiddynamics:

Sloshing is a problem with which anyone who has carried an overly full cup is familiar. Because of their freedom to flow and conform to any shape, fluids can shift their shape and center of mass drastically when transported. The issue can be especially pronounced in a partially-filled tank. The sloshing of water in a tank on a pick-up truck, for example, can be enough to rock the entire vehicle. One way to deal with sloshing is actively-controlled vibration damping - in other words, making small movements in response to the sloshing to keep the amplitude small. This is exactly the kind of compensation we do when carrying a mug of coffee without spilling. (Image credit: Bosch Rexroth; source)

fuckyeahfluiddynamics:

A Leidenfrost droplet impregnated with hydrophilic beads hovers on a thin film of its own vapor. The Leidenfrost effect occurs when a liquid touches a solid surface much, much hotter than its boiling point. Instead of boiling entirely away, part of the liquid vaporizes and the remaining liquid survives for extended periods while the vapor layer insulates it from the hot surface. Hydrophilic beads inserted into Leidenfrost water droplets initially sink and are completely enveloped by the liquid. But, as the drop evaporates, the beads self-organize, forming a monolayer that coats the surface of the drop. The outer surface of the beads drys out, trapping the beads and causing the evaporation rate to slow because less liquid is exposed. (Photo credit: L. Maquet et al.; research paper - pdf)

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