Recent content by Enthalpy

Hello everybody! Areva is supposed to build a plant in China to reprocess spent nuclear fuel (agreement hoped in Spring 2018). I should like to remind that the radioactive 85Kr fission product, which stays in the fuel rods until they're opened, can be stored easily until it has decayed, as I...

Hi Drakkith and the other, thanks for your interest! Well, if someone has already seen a Kalman filter at a gravitational wave interferometer, or knows the function of the auxiliary mirror of Kagra, or knows a better reason why Kagra's chamber will be so cold, or has seen light cooling...

Cooling by light needs the de-excitation to be almost always radiative, and meanwhile I doubt that shallow acceptors in a semiconductor de-excite radiatively: angular momenta may well forbid it. A three-level scheme should be better, where heat populates partly a shallow acceptor level, light...

Kagra's main Fabry-Perot mirrors absorb 400mW of the light, to be evacuated from 20K where radiation would be difficult. Kagra foresees several wires of pure aluminium, thin and long so their thermal noise shakes the mirrors very little. Far less simple, but it should be quieter: I suggest to...

The Kagra or Lcgt project, a cryogenic gravitational wave interferometer being built at the Kamioka mine in Japan http://en.wikipedia.org/wiki/KAGRA shows a secondary mirror and beam in but-last position of the suspension chain, resembling much what I describe. See figure 4 of: "Present status...

The D=1.25m vacuum tube of Ligo is made of 3mm 304L stainless steel with stiffeners http://core.kmi.open.ac.uk/download/pdf/4870869.pdf and perhaps maybe 4mm of aluminium extrusion are cheaper. Whether the longer weld seams are affordable is unclear. Also, the steel was baked at 444°C to desorb...

The Kálmán filter doesn't need a second tube - good, since the tubes make much of the observatory's cost. Movements assessed at each end of the tubes can feed the filter. I propose here to keep the observation of noise by light and deep at the suspension chain, as this is cleaner than an...

Hello everybody! Extreme interferometers like Ligo, Virgo, Leo600, Tama300 try to detect gravitational waves http://en.wikipedia.org/wiki/Gravitational-wave_detector and ground movements are one difficulty for them. The mirrors are suspended in several stages to insulate them, sometimes...

The pressure in the reserve brakes when there is no pressure in the brake pipe. This is intended, so that uncoupling the wagons from the locomotive let's them brake automatically. To move the uncoupled wagons, one has to manually purge the reserve.

I check this point precisely because I won't take as secure information what the train company tells and the Press repeats. Here's a doc telling that automatic air brake is the standard in Canada, and that brakes apply by decreasing pressure in the brake pipe...

Thank you! The patent claimed and exploited by Mr Westinghouse in the US describes a brake that releases by pressure and brakes by pressure drop. He sold enough of them to grow a big company. When was that abandoned? Sorting out wagons by a hill is done in Europe as well, so there is some...

Hi! An attempted explanation for the tragedy of Lac-Megantic is that the only running locomotive was shut down by the fire brigade when extinguishing it, and as this locomotive stopped to provide pressurized air to the train, the wagon's brakes opened and the train ran away. Which I can't...

Agree with 10.2kN. For that force, a 30mm bolt is hugely oversized, requiring too much torque. The fine pitch needs too many turns but doesn't reduce the torque. For comparison, an M16 10.9 pulls 100kN at usual pre-tension. The torque results essentially from friction at the screw: - At the...

You can put force sensors at varied chair locations in contact with the body: buttock, back, shoulder blades... The biggest difficulty I see, independently of where and how, is that the user wants to do more in the chair than move. You need some way to tell the chair not to interpret every...

I have such mission designs in the pipe, sure... I had investigated them in 2010 but with a wrong isp. Now with isp=1267 by a more detailed design, they still look interesting, including a Mars scenario where both the transit and the stay are short. Preset much in Martian orbit. I considered...