petschge

46 ms·

391.
by petschge 7y ago
Peer review isn't (and never was meant to be) a golden seal declaring a result to be unchangeable truth. It is a process that makes sure that at least one competent colleague has read it and caught all the embarrassing Monday morning m
392.
by petschge 7y ago
Galileo is still in deployment and a month ago they had an issue in the not-fully-redundent-yet ground segment that lead to 6 days with increasingly pure accuracy and partial outage.
393.
by petschge 7y ago
It is not just the political will that is lacking. The is no economic reason to do it. The maintenance can not be done by humans and if -- after a lot of investment -- you are able to develop robots that can do it, you get a better ROI by b
394.
by petschge 7y ago
Well, lay people have no clue. And probably should not be in charge of funding.
395.
by petschge 7y ago
ITER is far behind that growth curve because its cost is beyond what a university or national research lab is filling to fund. To unlike a lot of other projects before it, it is this massively political beast. Involving politician by itself
396.
by petschge 7y ago
Except that fusion reactor have a bunch of advantages over all fission designs, including breeder and molten core Thorium, that you conveniently ignore. The big one is: ramp up time is measured in minutes not days. This is a perfect additio
397.
by petschge 7y ago
That is only true out till (a litle past) Mars orbit. For deep space mission solars performance in terms of Watts per weight quickly becomes pretty bad. The 1/r^2 drop in solar flux eats your lunch there.
398.
by petschge 7y ago
If your supply of Deuterium and Tritium was jammed wide open you, would stop the fusion (either by switching of the heating if you are in startup or by messing with the magnetic confinement to make the plasma hit the diverter). At that poin
399.
by petschge 7y ago
Kokkos (as in the C++ template frame work and a lot of tools to get insights into bottle necks) is opens source. See https://github.com/kokkos/kokkos and https://github.com/kokkos/kokkos-tools . T
400.
by petschge 7y ago
I don't work for ORNL and don't know what their take in this is, but a lot of codes that the DoE uses are being ported to the Kokkos framework out of the Sandia National Lab. The application developer at that point basically doesn
401.
by petschge 7y ago
The thing with GNSS is that it is WELL below the noise flow and you need a lot of coding gain to receive it. That on the other hand really reduced the data rate at this you can transmit secondary information such as ephemeris and slowly cha
402.
by petschge 7y ago
I US actually has ok railways ... for fright. Commuter trains are admittedly underdeveloped, even in regions that have similar size and population density to European countries.
403.
by petschge 7y ago
These are called railways and every civilized country already has them.
404.
by petschge 7y ago
Closer than 51 North? you mean like all of the continental US?
405.
by petschge 7y ago
The usual quip in the industry is that the remote maintenance is such a complicated robotics problem. that which ever company is able to solve it, is better off converting to a robotics company and just drive Kuka, Fanuc and ABB out of busi
406.
by petschge 7y ago
This looks pretty good, but notice how it does not split "log(difference_squared" into two tokens. Adding '(' and ')' as delimiters should fix that.
407.
by petschge 7y ago
Radio astronomy has always been pushing the frontier of signal processing. Gamma ray telescopes also need large amounts of data crunching. Until recently optical telescope where much more about instrumentation than data processing. But even
408.
by petschge 7y ago
It is possible that the neutron emission number I found and used includes self shielding or is simply wrong. if the activity is 2.78e16 decays per second and not just 1.1e15/s then the decay heat would be about 30kW. But to be honest I
409.
by petschge 7y ago
You are right, the 700kW was wrong. The calculation I did was as follows (and I will point out the mistake I made): 1.4 kg is 1.4e9 micrograms and as per [1] "one microgram emits 170 million neutrons per minute" will emit 1.4e9 *
410.
by petschge 7y ago
The image labeled "Californium bullet" actually shows laboratory neutron sources that contain 5 mg of Californium. The rest of the "bullet" is actually a stainless steel casing. The metal shaving further down the page ar
411.
by petschge 7y ago
Critical mass of Cf-249 is 6kg, of Cf-251 5.46kg and of Cf-252 is 2.73kg. So no it would not go critical. 1.4 kg of Cf-252 would however emit something like 4e15 neutrons per second and 1.2kW (I first thought it was 700kW) of decay heat. Gl
412.
by petschge 7y ago
Uber and Lyft exploit drivers and are only around because they can finance their losses through venture capital. Which they only get because the promise autonomous cars that will never come and because the taxi industry was broken due to la
413.
by petschge 7y ago
Sorry, but a stack overflow answer (that doesn't even seem to be written by you) that give a bad overview over how X11 does it is not an explanation of why it can not be done. Or why it should not be done given that all platforms devel
414.
by petschge 7y ago
Sorry if I misread your comment and thanks for editing it to make it clearer. But why are you so opposed to having this featured backed into the display system? After all you point out yourself that all display systems and up with solutions
415.
by petschge 7y ago
And I use remote operations all day every day. As does the entire department with hundreds of people. Don't dismiss other peoples works flows without understanding them.
416.
by petschge 7y ago
Actually in a lot of cases turning heat into steam is MORE efficient than alternatives. Direct thermoelectric conversion has an efficiency of 5% to 10%, whereas multistage steam turbines are 36% - 42% efficient. This is also the reason why
417.
by petschge 7y ago
Efficiencies between 5% and 10% are pretty typical for thermoelectric devices. So getting 110W out of 2kW decay heat is about what you would expect. The RTGs on board the Voyager spacecrafts initially produced 2.4kW thermal power of which 1
418.
by petschge 7y ago
Actually you can make use of non-randomness in Monte Carlo simulations to get better results. There is various names for this, but the one I like best is "low discrepancy series". Have a look at [1] or [2] for a quick intro. These
419.
by petschge 7y ago
Reminds me of my office (in the US) where they heat the place to 26C in winter and cool it to 16C in summer.
420.
by petschge 7y ago
While technically present at all scales, gravity is so weak that you can ignore it until you get to pretty large scales. Meters or so. An ant barely feels gravity, a bacterium or a single cell don't even know it is there.

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