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Nina Nadine Ridder

Testing shows using microwaves to propel a craft into space might work - 4 views

phys.org/...owaves-propel-craft-space.html

technology propulsion microwaves science

shared by Nina Nadine Ridder on 23 Jul 15 - No Cached
Thijs Versloot and jcunha liked it
  • Nina Nadine Ridder on 23 Jul 15
     
    A team of researchers at Colorado based Escape Dynamics is reporting that initial tests indicate that it might really be possible to launch space-planes into space using microwaves sent from the ground, to allow for a single stage spacecraft. If the idea pans out, the cost savings for sending satellites (or perhaps humans) into orbit could be considerable.
  • Thijs Versloot on 27 Jul 15
     
    Not very new, but a very slick video nonetheless! Will it work? I am not so sure whether "just engineering" applies in this case. The array of antenna's required is quite significant to compensate for beam losses. Wall plug efficiency is not that high therefore, then again.. solar energy is for free almost in the future so who cares.. let's go for it! :)
Thijs Versloot

3D Printable Graphene Composite - 1 views

www.nature.com/srep11181

technology energy storage graphene 3d

shared by Thijs Versloot on 21 Jul 15 - No Cached
LeopoldS liked it
  • Thijs Versloot on 21 Jul 15
     
    Both graphene and 3d printing has been around for quite a while, but combined they could provide unique properties of materials, eg in the use of high performance 3d batteries. This paper gives a nice overview of what has been done in the field up to now.
Alexander Wittig

WorldWide Telescope - 2 views

worldwidetelescope.org

space technology

shared by Alexander Wittig on 06 Jul 15 - Cached
  • Alexander Wittig on 06 Jul 15
     
    Worldwide Telescope enables your computer to function as a virtual telescope, bringing together imagery from the best telescopes in the world. I managed to crash it twice in 20 minutes, but otherwise quite nice. Maybe Ingmar can add the GTOC solution in it ;)
  • Thijs Versloot on 07 Jul 15
     
    Wow, it also supports the Oculus! I see a new application to install :)
Dario Izzo

Optimal Control Probem in the CR3BP solved!!! - 7 views

math.u-bourgogne.fr/...research

OCP CR3BP trajectory MAD

shared by Dario Izzo on 07 Jun 11 - No Cached
  • Dario Izzo on 07 Jun 11
     
    This guy solved a problem many people are trying to solve!!! The optimal control problem for the three body problem (restricted, circular) can be solved using continuation of the secondary gravity parameter and some clever adaptation of the boundary conditions!! His presentation was an eye opener ... making the work of many pretty useless now :)
  • ...13 more comments...
  • Ma Ru on 08 Jun 11
     
    Riemann hypothesis should be next... Which paper on the linked website is this exactly?
  • Joris _ on 08 Jun 11
     
    hmmm, last year at the AIAA conference in Toronto I presented a continuation approach to design a DRO (three-body problem). Nothing new here unfortunately. I know the work of Caillau, although interesting what is presented was solved 10 years ago by others. The interest of his work is not in the applications (CR3BP), but in the research of particular regularity conditions that unfortunately make the problem limited practically. Look also at the work of Mingotti, Russel, Topputo and other for the (C)RTBP. Smart-One inspired a bunch of researchers :)
  • Dario Izzo on 08 Jun 11
     
    Topputo and some of the others 'inspired' researchers you mention are actually here at the conference and they are all quite depressed :) Caillau really solves the problem: as a one single phase transfer, no tricks, no misconvergence, in general and using none of the usual cheats. What was produced so far by other were only local solutions valid for the particular case considered. In any case I will give him your paper, so that he knows he is working on already solved stuff :)
  • Dario Izzo on 08 Jun 11
     
    Answer to Marek: the paper you may look at is: Discrete and differential homotopy in circular restricted three-body control
  • Joris _ on 08 Jun 11
     
    Ah! with one single phase and a first order method then it is amazing (but it is still just the very particular CRTBP case). The trick is however the homotopy map he selected! Why this one? Any conjugate point? Did I misunderstood the title ? I solved in one phase with second order methods for the less restrictive problem RTBP or simply 3-body... but as a strict answer to your title the problem has been solved before. Nota: In "Russell, R. P., "Primer Vector Theory Applied to Global Low-Thrust Trade Studies," JGCD, Vol. 30, No. 2", he does solve the RTBP with a first order method in one phase.
  • Joris _ on 08 Jun 11
     
    I think what is interesting is not what he solved, but how he solved the problem. But, are means more important than end ... I dunno
  • Dario Izzo on 08 Jun 11
     
    I also loved his method, and it looked to me that is far more general than the CRTBP. As for the title of this post, OK maybe it is an exageration as it suggests that no solution was ever given before, on the other end, as Marek would say "come on guys!!!!!"
  • Joris _ on 09 Jun 11
     
    The generality has to be checked. Don't you think his choice of mapping is too specific? he doesn't really demonstrate it works better than other. In addition, the minimum time choice make the problem very regular (i guess you've experienced that solving min time is much easier than mass max, optimality-wise). There is still a long way before maximum mass+RTBP, Topputo et al should be re-assured :p Did you give him my paper, he may find it interesting since I mention the homotopy on mu but for max mass:)
  • Dario Izzo on 09 Jun 11
     
    Joris, that is the point I was excited abut, at the conference HE DID present solutions to the maximum mass problem!! One phase, from LEO to an orbit around the moon .. amazing :) You will find his presentation on line.... (according to the organizers) I gave him the reference to you paper anyway, but no pdf though as you did not upload it on our web pages and I could not find it in the web. So I gave him some bibliography I had with be from the russians, and from Russell, Petropoulos and Howell, As far as I know these are the only ones that can hope to compete with this guy!!
  • Joris _ on 09 Jun 11
     
    for info only, my phd, in one phase: http://pdf.aiaa.org/preview/CDReadyMAST08_1856/PV2008_7363.pdf I prefered Mars than the dead rock Moon though!
  • Dario Izzo on 09 Jun 11
     
    If you send me the pdf I can give it to the guy .. the link you gave contains only the first page ... (I have no access till monday to the AIAA thingy)
  • LeopoldS on 11 Jun 11
     
    this is why I like this Diigo thingy so much more than delicious ...
  • tvinko on 17 Jun 11
     
    What do you mean by this comment, Leopold? ;-) Jokes apart: I am following the Diigo thingy with Google Reader (rss). Obviously, I am getting the new postings. But if someone later on adds a comment to a post, then I can miss it, because the rss doesn't get updated. Not that it's a big problem, but do you guys have a better solution for this? How are you following these comments? (I know that if you have commented an entry, then you get the later updates in email.) (For example, in google reader I can see only the first 5 comments in this entry.)
  • LeopoldS on 18 Jun 11
     
    I like when there are discussions evolving around entries
  • LeopoldS on 18 Jun 11
     
    and on your problem with the RSS Tamas: its the same for me, you get the comments only for entries that you have posted or that you have commented on ...
Alexander Wittig

Neuronal Networks: Computers paint like van Gogh - 1 views

www.spiegel.de/...maelde-aussehen-a-1051084.html

AI

shared by Alexander Wittig on 03 Sep 15 - No Cached
  • Alexander Wittig on 03 Sep 15
     
    A neuronal network trained to paint the scene of a given photograph in the style of Kandinsky, van Gogh, or Munch. Their results look quite impressive. Unfortunately the article is in German, but the English paper (with plenty of pictures) is here: http://arxiv.org/pdf/1508.06576v2.pdf Malen wie Kandinsky, wie van Gogh, wie Munch nur auf Basis einer Fotovorlage? Natürlich gibt es begabte Kunstfälscher, die das können. Jetzt aber gelingt es auch Computern, und zwar auf höchst eindrucksvolle Weise. Drei Forscher von der Universität Tübingen haben es geschafft, einem sogenannten künstlichen neuronalen Netzwerk das Malen beizubringen.
  • Luís F. Simões on 03 Sep 15
     
    Impressive stuff indeed. Paper came out one week ago. Multiple independent implementations have popped out since then: * https://github.com/Lasagne/Recipes/blob/master/examples/styletransfer/Art%20Style%20Transfer.ipynb * https://github.com/jcjohnson/neural-style * https://github.com/kaishengtai/neuralart
Thijs Versloot

This "Space Glass" Lets You Drink Whiskey In Orbit - 3 views

www.iflscience.com/ly-let-you-drink-whiskey-orbit

shared by Thijs Versloot on 09 Sep 15 - No Cached
  • Thijs Versloot on 09 Sep 15
     
    Photo credit: The glass has a number of interesting innovations. Ballentine's. A liquor company has created a " Space Glass" that they say can work in the microgravity environment of space. The Open Space Agency's James Parr was commissioned to create the product, and the results are actually quite interesting.
  • jcunha on 10 Sep 15
     
    Makes sense specially after seeing very good japanese whiskey arriving at the ISS :-) http://phys.org/news/2015-08-japanese-whisky-international-space-station.html
jcunha

scrible | smarter online research - annotate, organize & collaborate on web pages - 2 views

www.scrible.com

research Googling website organization

shared by jcunha on 31 Jul 15 - Cached
  • jcunha on 31 Jul 15
     
    A personal need for organizing the information I access online, going away from the pdf print of page, or browser tab just lying open for ages (Anna style) brought me here. Seems to be a quite good and featureful service, sponsored by the NSF.
  • LeopoldS on 14 Sep 15
     
    not convinced ... still stick to pdf for time being
  • Paul N on 16 Sep 15
     
    NSF, NSA, more or less the same. I'm growing increasingly weary about giving increasingly more private data away to online services.
jcunha

Where Life Meets Light: Bio-Inspired Photonics - 0 views

www.osa-opn.org/...s_light_bio-inspired_photonics

BIO biomimetics science FUN technology

shared by jcunha on 18 Jun 15 - No Cached
  • jcunha on 18 Jun 15
     
    Octopus and optoelectronics camouflage, light bugs and LEDs, or spider webs and touch screens, ... a whole cool bunch of biomimetic stuff
  • jcunha on 18 Jun 15
     
    See also the referred work "Light-extraction enhancement for light-emitting diodes: a firefly-inspired structure refined by the genetic algorithm" - quite cool! https://pure.fundp.ac.be/portal/files/11946897/paper89.pdf
aborgg

Graphene sponge can absorb light and emit energetic electrons for breakthrough solar sa... - 1 views

nextbigfuture.com/...onge-can-absorb-light-and.html

space technology

shared by aborgg on 04 Aug 15 - No Cached
  • aborgg on 04 Aug 15
     
    The unique structure and properties of graphene and the morphology of the bulk graphene material make it capable of not only absorbing light at various wavelengths but also emitting energetic electrons efficiently enough to drive the bulk material following Newtonian mechanics.
  • aborgg on 04 Aug 15
     
    Hard to believe this should actually work, but would be quite a breakthrough indeed. I wonder, since the material should build up a significant electric potential over time, thus, pulling back the ejected electrons. Well, the paper apparently is not peer-reviewed, and I found some rather critical comments in some forums. Let's see if the experiment will be verified by another research team in due course.
Ma Ru

Where are all the bookmarks? - 8 views

seems there is some problem here, 0 items, but a lot of tags used quite a lot, also the email notification for bookmarks still work so ..

fun

started by Ma Ru on 29 Sep 09 2 follow-ups, last by Ma Ru on 29 Sep 09
Francesco Biscani

Claimed Proof That P != NP - 4 views

science.slashdot.org/...Claimed-Proof-That-P--NP

inf

shared by Francesco Biscani on 09 Aug 10 - Cached
LeopoldS liked it
  • Ma Ru on 10 Aug 10
     
    Yet another one? Wish him good luck... I doubt anyone will waste time peer-reviewing his article. Here's quite a nice overview of the efforts on the problem: http://www.win.tue.nl/~gwoegi/P-versus-NP.htm
  • LeopoldS on 11 Aug 10
     
    thanks Marek - very nice link indeed ... did not know about it
Nicholas Lan

Letter from Intergovernmental panel on climate change. - 2 views

docs.google.com/fileview

environment climate change

shared by Nicholas Lan on 21 Jul 10 - No Cached
  • Nicholas Lan on 21 Jul 10
     
    To Coordinating Lead Authors, Lead Authors, and Review Editors for the Fifth Assessment Report (AR5) "I would also like to emphasize that enhanced media interest in the work of the IPCC would probably subject you to queries about your work and the IPCC. My sincere advice would be that you keep a distance from the media and should any questions be asked about the Working Group with which you are associated, please direct such media questions to the Co-chairs of your Working Group and for any questions regarding the IPCC to the secretariat of the IPCC." and an amusing related memo on how to deal with reporters if you can't avoid them. I particularly enjoyed the list of words that mean one thing to scientists and something else to other people. https://docs.google.com/fileview?id=0B88iFXWgVKt-NDc2N2FiM2QtYzQzYS00MWMxLWE4MGEtZjUwZDlmNzc3MTcz&hl=en
  • ...4 more comments...
  • Ma Ru on 21 Jul 10
     
    This. Memo. Is. Awesome.
  • pacome delva on 21 Jul 10
     
    quite weird this note of IPCC... I feel more like people have to be educated...
  • Nicholas Lan on 21 Jul 10
     
    i agree. however, (and perhaps it would have been useful to post my source which didn't seem so interesting at the time) the contents of this particular memo seems to have been interpreted as a more or less direct consequence of "ClimateGate" rather than standard practice. http://freakonomics.blogs.nytimes.com/2010/07/14/what-we-talk-about-when-we-talk-about-climate-change/ On the other hand, I'd suggest that talking to the press is not necessarily a great way of educating the public, there being some truth i think to the contents of the memo.
  • LeopoldS on 21 Jul 10
     
    don't know why this seems weired or shocking - looks like some good practice advice to me
  • pacome delva on 21 Jul 10
     
    well compare to ESA it's sure it doesn't seem weird. Imagine one second a journal article about climate change: "We contacted Dr. X of the IPCC, who refused to answer to our questions..."
  • LeopoldS on 22 Jul 10
     
    this is not what the memo recommends ... it just says speak only about what you can confidently speak about and refer to others for other questions ...
Nina Nadine Ridder

Smart grids - The IET - 0 views

www.theiet.org/...smartgrids.cfm

smart_grids sustainable_energy talk

shared by Nina Nadine Ridder on 25 Aug 10 - Cached
  • Nina Nadine Ridder on 25 Aug 10
     
    talk about European Technology Platform SmartGrids in Paris on the 7th Sep, 19h
  • Nina Nadine Ridder on 25 Aug 10
     
    in case somebody is in Paris on the 7th Sep. - sounds quite interesting
andreiaries

SPACE.com -- Huge Satellite Poses 150-Year Threat of Space Debris - 1 views

www.space.com/...lite-debris-threat-100726.html

space technology

shared by andreiaries on 30 Jul 10 - Cached
  • andreiaries on 30 Jul 10
     
    ESA is still at the forefront of space debris developments. But we do have a brilliant idea from the public: "Pay Communist China to shoot it down."
  • Ma Ru on 02 Aug 10
     
    Just in case you don't realise, it's the one which model is next to the Space EXPO :-) Quite a piece of debris...
Ma Ru

Yet another issue to take into account when you want to travel at c - 1 views

www.newscientist.com/...lls-especially-warp-speed.html

PHY interstellar travel human spaceflight speed of light

shared by Ma Ru on 19 Feb 10 - Cached
  • Ma Ru on 19 Feb 10
     
    While my attitude to articles about interstellar travel is generally sceptical, this one seems to raise quite an interesting point... Physicists?
  • ...1 more comment...
  • pacome delva on 19 Feb 10
     
    mmm, I think that if we manage to travel at 99.999998 per cent the speed of light, we'll have the technology to deviate these atoms ! one way could be a super strong magnetic field, or a super laser that would act as an ice breaker with the radiation pressure (the good thing is that light always travel at the speed of light, even if you are at 99.999998 per cent the speed of light)
  • Francesco Biscani on 19 Feb 10
     
    Also, remember never to dereference null pointers.
  • Ma Ru on 19 Feb 10
     
    True, it's almost like installing accelerometers upside down...
Francesco Biscani

Gigapixel-Dresden.de - Large Size Panoramas - 4 views

www.dresden-26-gigapixels.com/dresden26GP

fun

shared by Francesco Biscani on 18 Feb 10 - Cached
pacome delva liked it
  • The picture was made with the Canon 5D mark II and a 400mm-lens. It consists of 1.665 full format pictures with 21.4 megapixel, which was recorded by a photo-robot in 172 minutes.
  • Ma Ru on 18 Feb 10
     
    "With a resolution of 297.500 x 87.500 pixel (26 gigapixel) the picture is the largest in the world. (stand December 2009)" Daring statement... I'm not quite sure, but I'd quess microscopic images used in medicine can easily reach terapixels... What a waste of pixels anyway... they weren't able to find a bit more interesing city?
  • pacome delva on 23 Feb 10
     
    yeah... like Leiden !
Juxi Leitner

Technology Review: Blogs: arXiv blog: Physicist Discovers How to Teleport Energy - 4 views

www.technologyreview.com/...24759

tech phy quantum entanglement nrg

shared by Juxi Leitner on 09 Feb 10 - Cached
pacome delva liked it
  • He gives the example of a string of entangled ions oscillating back and forth in an electric field trap, a bit like Newton's balls. Measuring the state of the first ion injects energy into the system in the form of a phonon, a quantum of oscillation. Hotta says that performing the right kind of measurement on the last ion extracts this energy. Since this can be done at the speed of light (in principle), the phonon doesn't travel across the intermediate ions so there is no heating of these ions. The energy has been transmitted without traveling across the intervening space.
  • Juxi Leitner on 09 Feb 10
     
    wonder if we can use that to power a moon base .... or on-board a SBSP satellite
  • ...1 more comment...
  • LeopoldS on 09 Feb 10
     
    will still have to read the actual article but am a bit sceptic if this interpretation really will hold ... what are our fundamental physicists saying about this?
  • Juxi Leitner on 10 Feb 10
     
    I am not the physicist but I thought it might be interesting, from a space security point-of-view
  • pacome delva on 11 Feb 10
     
    Yes it seems really interesting and opens new possibilities. However this technology review article is not very good and the guy uses terms which have a precise meaning (like teleportation), which is different from the word we know... Quantum teleportation is what we use for designing quantum computers, but we are quite far from any practical applications. This energy teleportation will allow new scheme involving energy (if it is experimentally confirmed) which is very nice. However it seems this occurs in an entangled many-body system, which the only macroscopic one I know is a bose-eintein condensate (BEC). So it would mean infuse energy in the BEC by doing a measurement on one of the atom and extract it few millimeters away by doing a measurement on another atom. very far from any long distance power transmission...
pacome delva

981.pdf (Objet application/pdf) - 6 views

www.seo.nl/...981.pdf

shared by pacome delva on 14 Dec 09 - No Cached
  • pacome delva on 14 Dec 09
     
    Where do you want to go to do academic research and still have a decent salary ? certainly not sweden, France or Germany... prefer the UK, US or the top... Switzerland !
  • ...2 more comments...
  • Luzi Bergamin on 14 Dec 09
     
    Where do you want to go to do academic research and still have fun? Where can you really do research instead of becoming an overpaid secretary? If you want to get rich go and work in investment banking...
  • pacome delva on 14 Dec 09
     
    well.. i'd better live decently than get rich... which is not possible in Paris (take 1680 euros for one family and a 1000 euros rent, minus all normal expenses (health, car, insurance, ...), it's difficult to finish the month...) Without mentioning that in France you would become an underpaid secretary...!!! My ex phd director is a professor and she doesn't even have a secretary to manage the 150 applications to the master she is in charge... My experience would rather say that the salary and the time you have for research are quite decorrelated.
  • Luzi Bergamin on 14 Dec 09
     
    Sure, 44k for a full professor, that's a bad joke! Just my experience from conferences: high saleries do not make good research, I rather suspect there's something like an optimal salery. People with too high saleries often seem to feel obliged to make much noise (whatever the reason might be), the result is not research but PR campagns.
  • pacome delva on 14 Dec 09
     
    I agree ! Just a correction, net salary for a full professor starting in France: 36456 euros/year... For a McF (equivalent junior prof.): 20160 euros/year, and of course a shitload of admistrative tasks and teaching. I don't know why i still dream to have a position...?
nikolas smyrlakis

Your Favorite Sci-Fi Movies, 2000 and Beyond | Underwire | Wired.com - 0 views

www.wired.com/...5

sci-fi movies primer wired

shared by nikolas smyrlakis on 09 Dec 09 - Cached
  • nikolas smyrlakis on 09 Dec 09
     
    some ideas for movie Fridays A "must" see on my opinion (never heard about it in the past!) : Primer Sounds ideal: "Primer is a 2004 American science fiction film about the accidental discovery of time travel. The film was written, directed and produced by Shane Carruth, a mathematician and a former engineer, and was completed on a budget of $7,000.[1] Primer is of note for its extremely low budget, experimental plot structure and complex technical dialogue, which Carruth chose not to 'dumb down' for the sake of his audience. One reviewer said that "anybody who claims [to] fully understand what's going on in Primer after seeing it just once is either a savant or a liar."[2] The film collected the Grand Jury Prize at Sundance in 2004 before securing a limited release in US cinemas, and has since gained a cult following."
  • Ma Ru on 09 Dec 09
     
    I watched it a while ago during my studies in Belgium... The plot is quite well summarized on this diagram: http://xkcd.com/657/large/ According to the text above I'm either savant or a liar (you choose). But I watched the movie under significant exposure to Belgian beer, so this may have helped...
Luzi Bergamin

Impulse Januar 2010 (WebTV, NZZ Online) - 2 views

www.nzz.ch/...pulse_januar_10_1.4431278.html

inf hacking security

shared by Luzi Bergamin on 01 Feb 10 - Cached
  • Luzi Bergamin on 01 Feb 10
     
    Quite funny and interesting (even though I'm not known as a fan of those "gurus".) Site is in German, but interview in English.
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