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Marcus Maertens

Japan's Hayabusa2 probe makes second touchdown on distant asteroid | The Japan Times - 1 views

www.japantimes.co.jp/...ond-touchdown-distant-asteroid

space

shared by Marcus Maertens on 11 Jul 19 - No Cached
  • Marcus Maertens on 11 Jul 19
     
    Collecting space rocks.
  • Athanasia Nikolaou on 11 Jul 19
     
    if a geologist hears you calling them rocks they will curse you collectively. I am in a workshop where some of those are present and I constantly remind myself to call them "minerals".
  • LeopoldS on 09 Aug 19
     
    minerals sound much better indeed ... but what is wrong with rocks ? :-)
Luzi Bergamin

[1107.0167] Nonlinear transformation optics and engineering of the Kerr effect - 9 views

arxiv.org/1107.0167

PHY nan optics metamaterials

shared by Luzi Bergamin on 04 Jul 11 - No Cached
LeopoldS liked it
  • Luzi Bergamin on 04 Jul 11
     
    The best paper on transformation optics written ever :-)
  • ...2 more comments...
  • jmlloren on 05 Jul 11
     
    Finally something worth to read in the MM field!. The idea is excellent, congratullations. However, I think there is a typo or mistake in the definition of l=3x10-13 m, the "waist" of the laser beam. Seems clear that 0.3 pm is too small for being a waist of any laser beam.
  • Luzi Bergamin on 05 Jul 11
     
    Thanks for your commendation. Of course, the problem with nonlinear transformation optics is the same as with linear: it's very easy to come up with theoretical descriptions of devices that have the most absurd properties, but it will be extremely hard to fabricate them. But if you have any good suggestion, please shoot! About the laser beam: Pekka made the simulations, since I am not a "Comsolist", but still I think the numbers are correct. You are right that we should not call this a laser beam. Our problem was the following: we need to have a very simple model that can be simulated exactly (full Maxwell equations) but naturally exhibits self focusing. The Gaussian beam was the simplest solution. Since our model is purely classical and moreover we do not take into account diffraction effects, the parameter "l" is of minor importance. Taking "l" much larger gives almost the same picture but requires much more computer power to simulate. I guess that's why Pekka chose an unnaturally small number.
  • jmlloren on 05 Jul 11
     
    Concerning the fabrication... as usual, no idea. I agree that this is the main drawback of MM, and certainly difficult to overcome. I would double check that number, because its value is related with the beam shape of Fig. 1 A. I believe that the simulations are correct, it's just a detail.
  • LeopoldS on 06 Jul 11
     
    wow ... still publishing despite babysitting and new job!!
LeopoldS

Fooling automated surveillance cameras: adversarial patches to attack person detection - 3 views

arxiv.org/1904.08653.pdf

AI adversial ML

shared by LeopoldS on 24 May 19 - No Cached
icheibas liked it
  • LeopoldS on 24 May 19
     
    beautiful! anybody knows of similar trials to fool EO data classifiers?
  • icheibas on 24 May 19
     
    I am not aware of any similar trials, yet this study remind me of generative adversarial talking heads https://arxiv.org/pdf/1803.07716.pdf https://www.youtube.com/watch?v=p1b5aiTrGzY
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