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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 ...
2More

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
1More

Nature: Spawning rings of exceptional points out of Dirac cones - 3 views

www.nature.com/...nature14889.html technology lasers QM PHY Dirac Cone
shared by jcunha on 10 Sep 15 - No Cached
LeopoldS liked it
  • jcunha on 10 Sep 15
     
    Dirac cones, a band-structure of two cones touching each other, are the key to understand graphene exceptional properties. They also appear in the theory of photon waveguides and atoms in optical lattices. In here, the study of a Dirac cone deformation in an open system (a system that is perturbed by external agents) lead to the deformation of the Dirac cone, meaning a change in the fundamental properties of the system. This change is such that strange phenomena such as unidirectional transmission or reflection or lasers with single mode (really single) operation can be achieved. Proved experimentally in photonic crystals. New way for extremely pure lasers?
3More

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.
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OpenStack: An Open Source Cloud Project Emerges - 1 views

gigaom.com/openstack cloud computing IT
shared by LeopoldS on 19 Jul 10 - Cached
  • LeopoldS on 19 Jul 10
     
    Francesco, check this one out ... seems like coming at the right time for us ... Leopold
  • Francesco Biscani on 19 Jul 10
     
    Sure looks interesting, hopefully it will gain some traction. Bonus point it uses Python heavily :) First versions are coming out in Sept/Oct, according to their roadmap, we could start playing with it as soon as it gets out.
2More

Planck captures the universe coming to life - 1 views

physicsworld.com/...43110 phy cosmology planck
shared by pacome delva on 06 Jul 10 - Cached
  • ESA's Planck mission has released its first full-sky map. The image shows the cosmic microwave background (CMB) in higher resolution than ever before and it may help cosmologists to develop a much clearer picture of the early universe. "This is the moment that Planck was conceived for," says David Southwood, who is ESA's director of science and robotic exploration. "We are opening the door to an Eldorado where scientists can seek the nuggets that will lead to deeper understanding of how our universe came to be and how it works now."
  • pacome delva on 06 Jul 10
     
    coooool !
7More

You know you have been in Finland too long, when... - 4 views

www.hs.fi/toolong fun humor
shared by Luzi Bergamin on 23 Jun 10 - Cached
  • Luzi Bergamin on 23 Jun 10
     
    How you know you have been to long in xy. The Finnish version. My favorite is 33. You accept that 80°C in a sauna is chilly, but 20°C outside is freaking hot. Quite a lot of them are outdated, esp. about opening hours of shops, and one is definitely missing. Your normal mealtime has shifted to 11am for lunch and 5pm for dinner. But don't worry, it's a really comfy place here, isnt' it Jose??
  • ...4 more comments...
  • Juxi Leitner on 23 Jun 10
     
    well somethings you get used to in a year (like salmiakki or koskenkorva) others don't (seriously, lunch at 11?!?!)
  • Ma Ru on 23 Jun 10
     
    But what stage are you in already, Luzi?
  • Luzi Bergamin on 24 Jun 10
     
    I would say a 50% Finn. I do have lunch at 11am, every working day, an 80 degrees sauna indeed is just a warm room. But I will never get used to salmiakki (which is just literally eating a cleaning agent!!) and you can imagine that "silence is fun" is not really MY motto...
  • LeopoldS on 24 Jun 10
     
    True?? 22. You understand why the Finnish language has no future tense. No, I don't think I ever will understand that one... Finns are quite future-oriented at two particular times of the year. On the day after Midsummer (see above), they say "Well, it's all downhill from now on" and prepare feverishly for winter, and similarly after December 21st they perk up and start thinking about Midsummer - ignoring the fact that they still have to get through January, February and March before the place becomes inhabitable again...
  • Juxi Leitner on 24 Jun 10
     
    ... Finnish language has no future tense. That's true
  • LeopoldS on 25 Jun 10
     
    everything expressed with "tomorrow I go to " or "in one year" etc? what about the distinction between to future events, one conditional on the other?
1More

OpenLuna Picks Up Where NASA's Moon Mission Leaves Off - 0 views

ostatic.com/...-nasas-moon-mission-leaves-off MAD Open science
shared by Joris _ on 18 Aug 10 - Cached
  • The ambitious project will tap the resources of private enterprise to build several small scout rovers that will be shipped to the south pole of the moon via a single lander. Rock and earth samples will be returned to Earth for testing, then auctioned off to secure funding for the next phase of the plan
1More

Open Source Aerospace Project - 3 views

hobbyspace.com/nucleus pagmo inf opensource wiki
shared by Dario Izzo on 05 Aug 10 - Cached
LeopoldS liked it
  • Dario Izzo on 05 Aug 10
     
    similar idea to ours.... but implemented
3More

Slashdot Science Story | Calculating Environmental Damage From Space Tourism Rockets - 3 views

science.slashdot.org/...age-From-Space-Tourism-Rockets technology green environment danger rockets
shared by Juxi Leitner on 02 Nov 10 - No Cached
  • LeopoldS on 02 Nov 10
     
    Cynthia - please have a look ... can we check the OoM?
  • Juxi Leitner on 05 Nov 10
     
    http://www.nature.com/news/2010/101022/full/news.2010.558.html hmm should be the ACT in Nature, no? ;)
  • Ma Ru on 05 Nov 10
     
    Yeeesss :) So the "non-commercial" rockets do not emit soot? And how many "non-commercial" launches per year are there in comparison to the commercial ones? Finally commercial space-flight seems more realisable than ever, and "non-commercial" guys will do everything to prevent situation in which they have to compete on an open market... Coming years should be very interesting...
1More

Kitware Blog - VTK: an example on how to fix the crisis of scientific software - 2 views

www.kitware.com/67 open science inf
shared by Francesco Biscani on 08 Nov 10 - No Cached
  • Francesco Biscani on 08 Nov 10
     
    A nice blog post about a recent Nature paper highlighting the problems of scientific software.
5More

If you're going to do good science, release the computer code too!!! - 3 views

www.guardian.co.uk/...ce-climate-emails-code-release open science
shared by Dario Izzo on 09 Feb 10 - Cached
pacome delva liked it
  • Les Hatton, an international expert in software testing resident in the Universities of Kent and Kingston, carried out an extensive analysis of several million lines of scientific code. He showed that the software had an unacceptably high level of detectable inconsistencies.
  • pacome delva on 09 Feb 10
     
    haha. this guy won't have any new friends with this article! I kind of agree but making your code public doesn't mean you are doing good science...and inversely! He takes experimental physics as a counter example but even there, some teams keep their little secrets on the details of the experiment to have a bit of advance on other labs. Research is competitive in its current state, and I think only collaborations can overcome this fact.
  • ...1 more comment...
  • Juxi Leitner on 10 Feb 10
     
    well sure competitiveness is good but to verify (and that should be the case for scientific experiments) the code should be public, it would be nice to have something like bibtex for code libraries or versions used.... :) btw I fully agree that the code should go public, I had lots of trouble reproducing (reprogramming) some papers in the past ... grr
  • Francesco Biscani on 10 Feb 10
     
    My view is that the only proper way to do scientific communication is full transparency: methodologies, tests, codes, etc. Everything else should be unacceptable. This should hold both for publicly funded science (for which there is the additional moral requirement to give back to the public domain what was produced with taxpayers' money) and privately-funded science (where the need to turn a profit should be of lesser importance than the proper application of the scientifc method).
  • Dario Izzo on 08 Nov 10
     
    Same battle we are fighting since a few years....
5More

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...
3More

Why Can't PCs Work More Like iPhones? - Bits Blog - NYTimes.com - 1 views

bits.blogs.nytimes.com/...ant-pcs-work-more-like-iphones computing
shared by LeopoldS on 27 Feb 10 - Cached
  • LeopoldS on 27 Feb 10
     
    bye bye Francesco to your beloved command line ....
  • Francesco Biscani on 27 Feb 10
     
    I would love to see people working on touchscreens all day, orthopedics would have a field day :) Anyway, the answer to the original question is: because the JesusPhone is an appliance, a PC is not.
  • Luzi Bergamin on 01 Mar 10
     
    Luckily there is open source, so neither Steve Jobs nor NY Times decide for us what sort of OS we have to like! I'll join the "Jihad for the command line" troop!!
1More

Visualizing science - 2 views

vimeo.com/6644720 fun inf
shared by Ian Carnelli on 16 Feb 10 - Cached
  • Ian Carnelli on 16 Feb 10
     
    toxiclibs is an independent, open source library collection for computational design tasks with Java & Processing
1More

Better Nanotubes May Be on the Way -- Fox 2009 (1210): 3 -- ScienceNOW - 1 views

sciencenow.sciencemag.org/...3 phy nan carbon_nanotubes
shared by pacome delva on 14 Dec 09 - Cached
  • Success at building large amounts of inexpensive nanotubes opens the door for lighter, faster car frames; affordable space vehicles; and ultralightweight armor. Or on a smaller level, BNNTs could be used with pinpoint precision to attack cancer cells by sticking to tumors, absorbing neutrons from a targeted beam, and generating localized alpha radiation to kill the cancer. "This is the start of a revolution in materials," says Dennis Bushnell, a NASA engineer who has watched the work closely in the hopes of using BNNTs for space vehicles.
1More

RHIC nets strange antimatter - 0 views

physicsworld.com/...41917 strange_antimatter collider
shared by pacome delva on 08 Mar 10 - Cached
  • The antihypertriton – consisting of an antiproton, an antineutron and an antilambda particle – is the heaviest antinucleus yet produced and opens up a new realm of strange antinucluei. It could also shed light on a number of problems in astrophysics and cosmology, including the dominance of matter over antimatter in the universe.
7More

mentored by the Advanced Concepts Team for Google Summer of Code 2010 - 4 views

socghop.appspot.com/...advancedconceptsteam pagmo google summerofcode
shared by nikolas smyrlakis on 19 Mar 10 - Cached
LeopoldS liked it
  • nikolas smyrlakis on 19 Mar 10
     
    you propably already know,I post it for the twitter account and for your comments
  • ...4 more comments...
  • LeopoldS on 20 Mar 10
     
    once again one of these initiatives that came up from a situation and that would never have been possible with a top-down approach .... fantastic! and as Dario said: we are apparently where NASA still has to go with this :-)
  • Joris _ on 20 Mar 10
     
    Actually, NASA Ames did that already within the NASA Open Source Agreement in 2008 for a V&V software!
  • Joris _ on 20 Mar 10
  • LeopoldS on 20 Mar 10
     
    indeed ... you are right .... interesting project btw - they started in 1999, were in 2005 the first NASA project on Sourceforge and won several awards .... then this entry why they did not participate last year: "05/01/09: Skipping this years Google Summer-of-Code - many of you have asked why we are not participating in this years Summer of Code. The answer is that both John and Peter were too busy with other assignments to set this up in time. We will be back in 2010. At least we were able to compensate with a limited number of NASA internships to continue some of last years projects." .... but I could not find them in this years selected list - any clue?
  • LeopoldS on 20 Mar 10
     
    but in any case, according to the apple guru, Java is a dying technology, so their project might as well ...
  • Joris _ on 21 Mar 10
     
    They participate under the name "The Java Pathfinder Team" (http://babelfish.arc.nasa.gov/trac/jpf/wiki/events/soc2010). It is actually a very useful project for both education and industry (Airbus created a consortium on model checking soft, and there is a lot of research on it) As far as I know, TAS had some plans of using Java onboard spacecrafts, 2 years ago. Not sure the industry is really sensible about Jobs' opinions ;) particularly if there is no better alternative!
1More

New Material: Network of 'Streets' for Light - 1 views

focus.aps.org/st14 phy metamaterials waveguides
shared by pacome delva on 19 Apr 10 - Cached
  • In recent years, researchers have created early versions of "invisibility cloaks" and advanced optical fibers by manipulating light using structures composed of tiny, repeating units. In the 9 April Physical Review Letters, a team proposes a different way to make an artificial optical material--from a network of light-guiding filaments. If such structures are practical, they could open new ways to control light in technologies ranging from high-speed telecommunication to high-resolution imaging.
5More

Novel negative-index metamaterial bends light 'wrong' direction - 1 views

www.sciencedaily.com/...100422153939.htm phy nan metamaterials
shared by pacome delva on 23 Apr 10 - Cached
  • the first negative index metamaterial to operate at visible frequencies
  • By engineering a metamaterial with such properties, we are opening the door to such unusual -- but potentially useful -- phenomena as superlensing (high-resolution imaging past the diffraction limit), invisibility cloaking, and the synthesis of materials index-matched to air, for potential enhancement of light collection in solar cells
  • Luzi Bergamin on 23 Apr 10
     
    I forwarded the link to my experimental colleagues and here is the comment from Sergei (the master himself:) "this is what Igor has been doing - an array of plasmonic nanocables. This basically works as a wire-medium slab. All their epsilon and mu are rubbish." * If Sergei is as strict as in this comment, then it IS rubbish. He's not one of the notorious complainer (as e.g. myself.) * Please DO NOT FORWARD this to anybody else, Sergei's comment is NOT FOR PUBLIC USE!
  • Luzi Bergamin on 23 Apr 10
     
    UPDATE: I had a short chat with Sergei and Pekka, Sergei noticed that there is an increasing number of papers on metamaterials, especially in Nature and Science, which are simply wrong, this one being an example. * The idea is based on a very well known effect of wired media. What appears to be interesting about this paper is that they manage to make an optical analogue with aparently low losses. This could be interesting. * The whole interpretation as NIM, "wrong" refraction etc. is total nonsense.
  • pacome delva on 23 Apr 10
     
    wow, good to know ! But for the privacy you should be aware that this is a public group, so anyone has access to our comments i think !
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