petschge

47 ms·

481.
by petschge 7y ago
Not quite standard. The trick is to use backward differencing in time, to make it unconditionally stable even for longer time steps. Also the Poisson equation to get the pressure is only solved approximately by doing Jacobi iterations until
482.
by petschge 7y ago
Obtaining the delta from two different images is actually non trivial. And contrary to what HN thinks, not every problem is trivially solved by machine learning. Small point aside: an ultrasound scan -- even if it was every feasible at home
483.
by petschge 7y ago
Getting a baseline is harder than it sounds. In the case of blood chemistry that is caused by fluctuations due to time of day, time of month, season, what you recently ate and so one. In the case of MRI the problem is that internal organs s
484.
by petschge 7y ago
That article reports: If looking at the geometric mean for the tests run today, the Intel systems all saw about 16% lower performance out-of-the-box now with these default mitigations and obviously even lower if disabling Hyper Threading fo
485.
by petschge 7y ago
Wendelstein 7-X currently has done burns up to 26 seconds and the limit is not plasma instabilities, but wall heating. So now they are putting in water cooling and plan to have 30 minute burns within the next 2 years.
486.
by petschge 7y ago
Extra fun example: astronomy, especially radio astronomy definies left and right handed circular polarization exactly the opposite way to how optics does it...
487.
by petschge 7y ago
A planet can have a atmosphere that is sufficient for life, but of negligable mass compared to the core. In our solar system we have at least 2.5 examples of that: Earth, Venus and Mars. And that is not counting ocean moons with an ice crus
488.
by petschge 7y ago
You can get rid of the gas giant in your analysis by excluding everything further out than 0.2 AU. The distribution then separates more clearly into to peaks with a gap in between. But that is something I can not get in a minute or two in t
489.
by petschge 7y ago
If you check the histogram plot at exoplanet.eu (also at https://imagebin.ca/v/4hRAHBxEtEbv for your convenience) you see that the density is quite a bit lower. And "Fulton gap" is simply a better name than &
490.
by petschge 7y ago
This is indeed one of the possible theories to explain the Fulton gap, as far as I understand it. If you have a rocky core that accretes more and more atmosphere, the atmosphere collapses once it contains about as much mass as the core and
491.
by petschge 7y ago
Since a lot of people seem to have problems with that plot I have uploaded an annotated version to https://imagebin.ca/v/4hQOkAKo27fq . The black dots are data and are correct. The colorful annotations are by me and mi
492.
by petschge 7y ago
Physicists studying the sun and effect on its surface use megameter as a length scale quite a bit.
493.
by petschge 7y ago
It's a bit harder than that. We don't understand the effect, so we don't have a good _high level_ model of it. That does not mean we can not model it using more fundamental physics. But of course that leads to much more expen
494.
by petschge 7y ago
And how is Tritium, or rather super-heavy water that contains Tritium as one of its two hydrogen atoms, not a chemical?
495.
by petschge 7y ago
At this precision you weigh things twice. Once with the reference on the left arm of the balance and the test object on the right and another time with objects swapped.
496.
by petschge 7y ago
Do you have more information on that? "Hot jupiters" are close in gas planets and the should appear at low semi-major axis, above the Fulton gap. (Disclaimer: I am not a planetary scientist, but my office mate is and I learned jus
497.
by petschge 7y ago
There is no (known) selection effect that would account for that gap. (And scientists have looked to find such selection effects). And yes, there is other gaps, e.g. a lack of systems with a planet at 0.2 AU (or rather in the range from 0.
498.
by petschge 7y ago
I am not a planetary scientist (my office mate is) and didn't spend much time looking at the literature. "A Revised Exoplanet Yield from the Transiting Exoplanet Survey Satellite (TESS)" by Barclay et al. ( https://
499.
by petschge 7y ago
Let me reply to that we another example: If you fly an aircraft in GTA you are not doing a million-core-hour direct numerical simulation of the air flow around the jet. That doesn't mean it's not cool and playing with simplified m
500.
by petschge 7y ago
Go to http://exoplanet.eu/diagrams/ and select "Semi-major axis" for the X axis (this is the appropriate analog of "radius" for an ellipse) and "Planetary Mass" for the Y Axis. Note that t
501.
by petschge 7y ago
Orbits are stable and not sensitive to the objects mass, as long as the mass is much less than parent star. There is even experimental prove of that. An upper stage from the Apollo programm ended up in an orbit around that sun that was basi
502.
by petschge 7y ago
Depends how close to the parent star and how far that star is from us. But for earth sized planetes about 1 AU from the star we are rather blind.
503.
by petschge 7y ago
People are running models of planet formation. And some people run their model often enough to do statistics over the outcomes. The problem is that modelling the formation all the way from micron sized dust to 100000 km diameter planets is
504.
by petschge 7y ago
And the radiation that enters the water does nothing terrible there. If it is a alpha particle, it will scatter a few times, grab an electron and become a harmless helium atom. An electron from beta decay will be harmless after a few collis
505.
by petschge 7y ago
Radiation is released by specific chemicals. If what you said was true they would be easy to filter out.
506.
by petschge 7y ago
Ideally the network equipment would never see anything but encrypted traffic. There is no reason why a cell tower should be able to get access to the voice data of a call. Now of course we all know that the crypto at least in GSM was horrib
507.
by petschge 7y ago
The government deciding to not purchase that equipment for their own use in sensitive networks is one thing. (And this was already in place before this executive order.) Banning corporations from doing that in their own commercial networks
508.
by petschge 7y ago
How many extra lives are lost to obesity because children never learn how fun it is to move outdoors? Everything is so safe and non-fun. Of course the deaths 3 decades down the line are not attributed to overly safe playgrounds and overprot
509.
by petschge 7y ago
The fear mongering against Huawei becomes really interesting when you look at all the "sorry, we forgot about that unintentional access possibility" incidents in Cisco gear that might either be back doors or lousy QA leading to se
510.
by petschge 7y ago
Usually the first step is to correct from what ever the local clock at the observatory said to actual UTC. Then you convert from UTC to TAI. And then you convert from TAI to the arrival time at the solar barycenter, removing the geometric l

More ›