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santecarloni

Artificial Braneworlds Made to Collide In Lab - Technology Review - 4 views

www.technologyreview.com/...27537

metamaterials cosmology PHY

shared by santecarloni on 31 Jan 12 - No Cached
pacome delva liked it
  • santecarloni on 31 Jan 12
     
    Physicists have simulated two universes colliding inside a metamaterial--  Now, this is cool (if it is true...)
  • ...1 more comment...
  • LeopoldS on 01 Feb 12
     
    we... the article is a bit overblown in my view ... except maybe the last paragraphs: "The collision between universe's is a variation on this theme. "The "colliding universe" scenario can be realized as a simple extension of our earlier experiments simulating the spacetime geometry in the vicinity of big bang," he says. He simulates an expanding universe using concetric rings of gold separated by a dielectric. "When the two concentric ring ("universe") patterns touch each other ("collide"), a Minkowski domain wall is created, in which the metallic stripes touch each other at a small angle," he says. Being able to recreate these exotic events in the lab is certainly interesting but it is beginning to lose its novelty. The problem is that this work is not telling us anything we didn't know--the universe behaves the same way inside a metamaterial as it does outside. What Smolyaninov needs is a way of using his exotic materials to do something interesting. In other words, he needs a killer app. Any ideas? "
  • Luzi Bergamin on 05 Feb 12
     
    Hm, they use more or less everything I don't especially like. They are nonmagnetic, so the relation materialGR is already rather weak. Usually, experimentalists prefer nonmagnetic media, since they are cheaper and broadband. At least the broadband is no argument here, since the frequency defines the "mass", which I find a rather strange point of view. And finally, they use strong anisotropy as a model of "time", which is rather problematic. Of course, the spatial direction with eps<0 appears in the wave equation with the same sign as time. But this does not mean that it behaves like time. But to teach material physicists that time is more than just a different sign in the wave equation seems to be as hopeless as to teach them that a black hole is more than something that absorbs all light... SIGHHH
  • LeopoldS on 10 Feb 12
     
    Luzi I miss you ...
Luís F. Simões

Stochastic Pattern Recognition Dramatically Outperforms Conventional Techniques - Techn... - 2 views

www.technologyreview.com/...27598

stochastic probabilistic computing pattern_recognition robotics navigation

shared by Luís F. Simões on 23 Feb 12 - No Cached
  • A stochastic computer, designed to help an autonomous vehicle navigate, outperforms a conventional computer by three orders of magnitude, say computer scientists
  • These guys have applied stochastic computing to the process of pattern recognition. The problem here is to compare an input signal with a reference signal to determine whether they match. &nbsp; In the real world, of course, input signals are always noisy so a system that can cope with noise has an obvious advantage.&nbsp; Canals and co use their technique to help an autonomous vehicle navigate its way through a simple environment for which it has an internal map. For this task, it has to measure the distance to the walls around it and work out where it is on the map. It then computes a trajectory taking it to its destination.
  • Although the idea of stochastic computing has been around for half a century, attempts to exploit have only just begun. Clearly there's much work to be done. And since one line of thought is that the brain might be a stochastic computer, at least in part, there could be exciting times ahead.
  • ...1 more annotation...
  • Ref:&nbsp;arxiv.org/abs/1202.4495: Stochastic-Based Pattern Recognition Analysis
  • Luís F. Simões on 23 Feb 12
     
    hey! This is essentially the Probabilistic Computing Ariadna
  • LeopoldS on 25 Feb 12
     
    The link is there but my understanding of our purpose is different than what I understood from the abstract. In any case,the authors are from Palma de Mallorca, Balears, Spain "somebody" should somehow make them aware of the Ariadna study ... E.g somebody no longer in the team :-)
Thijs Versloot

The risk of geoengineering (or when abruptly stopping..) - 2 views

www.sciencedaily.com/...140217200823.htm

geoengineering

shared by Thijs Versloot on 19 Feb 14 - No Cached
  • Thijs Versloot on 19 Feb 14
     
    The researchers used a global climate model to show that if an extreme emissions pathway -- RCP8.5 -- is followed up until 2035, allowing temperatures to rise 1°C above the 1970-1999 mean, and then SRM (Solar Radiation Management) is implemented for 25 years and suddenly stopped, global temperatures could increase by 4°C in the following decades.
  • Athanasia Nikolaou on 19 Feb 14
     
    Nice quantitative study. They treat the problem within the full uncertainty range of climate sensitivity parameter (much uncertain), very complete. However, at SRM ceasing, after an initial positive spike of Radiative Forcing, the rate of warming seems to return to rates predicted for the non-geoengineering case: "The 20-year temperature trends following SRM cessation are 0.2−0.6 °C/decade for the range of climate sensitivities (figure 5), comparable to those trends that occur under the RCP8.5 scenario without any SRM." I am actually working on a similar idea for deliberate Mars terraforming: aiming to cool the planet down before we introduce a positive Temperature raising feedback with greenhouse gases, maybe could be more efficient than warming itself.
Tom Gheysens

First animals oxygenated the ocean -- ScienceDaily - 0 views

www.sciencedaily.com/...140309150540.htm

BIO science ocean

shared by Tom Gheysens on 10 Mar 14 - No Cached
  • Tom Gheysens on 10 Mar 14
     
    Now this is an interesting hypothesis! Would make terraforming a bit easier 
  • Athanasia Nikolaou on 11 Mar 14
     
    Having an ocean on Mars would solve so many problems... btw, again this guy? Isabelle take a look at that : Tim Lenton is everywhere, last time he wrote half of our literature references on the tipping points study.
johannessimon81

Air pollution weakens hurricanes - 3 views

tamutimes.tamu.edu/...ls-appear-to-weaken-hurricanes

science weather climate?

shared by johannessimon81 on 11 Mar 14 - No Cached
  • johannessimon81 on 11 Mar 14
     
    Problem solved.
  • ...1 more comment...
  • johannessimon81 on 11 Mar 14
     
    Also, tornados could be stopped from forming by building 300 m tall, 100 km long walls across the USA: http://www.wired.co.uk/news/archive/2014-03/08/tornado-walls
  • Thijs Versloot on 11 Mar 14
     
    Those would also work very well to keep the Kaiju's out..
  • johannessimon81 on 12 Mar 14
     
    Good point!
Luís F. Simões

Evolution of AI Interplanetary Trajectories Reaches Human-Competitive Levels - Slashdot - 4 views

science.slashdot.org/...aches-human-competitive-levels

AI MAD GTOC PaGMO evolutionary computation trajectory optimization awards

shared by Luís F. Simões on 19 Jul 13 - No Cached
  • "It's not the Turing test just yet, but in one more domain, AI is becoming increasingly competitive with humans. This time around, it's in interplanetary trajectory optimization. From the European Space Agency comes the news that researchers from its Advanced Concepts Team have recently won the Gold 'Humies' award for their use of Evolutionary Algorithms to design a spacecraft's trajectory for exploring the Galilean moons of Jupiter (Io, Europa, Ganymede and Callisto). The problem addressed in the awarded article (PDF) was put forward by NASA/JPL in the latest edition of the Global Trajectory Optimization Competition. The team from ESA was able to automatically evolve a solution that outperforms all the entries submitted to the competition by human experts from across the world. Interestingly, as noted in the presentation to the award's jury (PDF), the team conducted their work on top of open-source tools (PaGMO / PyGMO and PyKEP)."
  • Luís F. Simões on 19 Jul 13
     
    We made it to Slashdot's frontpage !!! :)
  • Ma Ru on 23 Jul 13
     
    Congratulations, gentlemen!
Thijs Versloot

The entropy of encryption and how secure is it? - 1 views

phys.org/...013-08-encryption-thought.html

encryption information technology

shared by Thijs Versloot on 16 Aug 13 - No Cached
  • Thijs Versloot on 16 Aug 13
     
    I like the following text: "It's still exponentially hard, but it's exponentially easier than we thought," Duffy says. One implication is that an attacker who simply relied on the frequencies with which letters occur in English words could probably guess a user-selected password much more quickly than was previously thought. "Attackers often use graphics processors to distribute the problem," Duffy says. "You'd be surprised at how quickly you can guess stuff."
johannessimon81

Kenia's water problems resolved: satellite data help find giant aquifer - 0 views

www.bbc.co.uk/...science-environment-24049800

science space

shared by johannessimon81 on 11 Sep 13 - No Cached
  • johannessimon81 on 11 Sep 13
     
    The underground lake is big enough to cover Kenia's water need for the next 70 years
Paul N

2012 study indicates drinking enhances creativity - 0 views

www.medicaldaily.com/-problem-solving-skills-240105

fun

shared by Paul N on 15 Nov 13 - No Cached
  • Paul N on 15 Nov 13
     
    And the actual paper link with some graphs: http://www.sciencedirect.com/science/article/pii/S1053810012000037
Thijs Versloot

Do the math #dothemath - 4 views

physics.ucsd.edu/do-the-math

blog science technology

shared by Thijs Versloot on 12 Nov 13 - No Cached
LeopoldS liked it
  • Thijs Versloot on 12 Nov 13
     
    My daily read, a collection of blog posts related mostly to energy by UCSD prof Tom Murphy. Especially his experiments into home energy storage and his "do the math" attitude towards renewables are insightful and if not, then sometimes just plain funny.
  • LeopoldS on 12 Nov 13
annaheffernan

Initial problems with first space toilets revealed :) - 1 views

www.huffingtonpost.com/...asa-transcripts_n_3054324.html

fun

shared by annaheffernan on 27 Sep 13 - No Cached
  • annaheffernan on 27 Sep 13
     
    On a lighter note: Decades after NASA's Apollo missions, people are having some laughs over transcripts of astronauts' humorous conversations aboard the spacecraft. For all their technological sophistication, the Apollo command module had a relatively primitive system for managing human waste.
Thijs Versloot

Ending overfishing #animation - 0 views

www.youtube.com/watch

shared by Thijs Versloot on 21 Nov 13 - No Cached
LeopoldS liked it
  • Thijs Versloot on 21 Nov 13
     
    Nice animation to summarize the current over fishing problem. For example, I never knew that farm raised fish (like salmon) actually are carnivorous and 5kg of fish is needed to produce 1kg of this 'higher quality' fish.
Thijs Versloot

Norway loves electric cars - 0 views

cleantechnica.com/...-cars-two-months-row-7-reasons

technology EV market

shared by Thijs Versloot on 03 Dec 13 - No Cached
  • Thijs Versloot on 03 Dec 13
     
    The main reasons: (1) awareness, people know that a variety of consumer cars exist (2) negative incentives that push people away from gasoline powered cars, eg fuel taxes (3) positive incentives, exemption from road tax, purchase tax and free parking (all temporary) and (4) extensive recharging infrastructure. Other countries have some/all of these elements, but Norway has pushes mostly and the result is that the nissan leaf was the best sold car in September and October, beating all other cars.
  • Ma Ru on 03 Dec 13
     
    If there's anyone who could afford such things, it is Norway... According to http://xkcd.com/980/, Oljefondet (http://en.wikipedia.org/wiki/Government_Pension_Fund_of_Norway) is currently worth nearly as much as US has spent on wars. I mean, all of them together... One of the biggest problems in Norway is what to do with this money without damaging the economy in the long run :-)
Ma Ru

F9R First Flight Test - 3 views

www.youtube.com/watch

F9R SpaceX space technology rocket landing launch

shared by Ma Ru on 27 Apr 14 - No Cached
LeopoldS liked it
  • Ma Ru on 27 Apr 14
     
    In case you have not seen this one yet...
  • Thijs Versloot on 28 Apr 14
     
    Nice one, very impressive (also filming it with a drone :)! I noticed at 0:56 that the exhaust flames do travel upwards on the descent. I wonder how much of a problem this would be for the actual reusability / next flight approval?
  • LeopoldS on 29 Apr 14
     
    impressive!
Thijs Versloot

China team takes on tech challenge of supercavitation - 1 views

phys.org/...team-tech-supercavitation.html

technology submarine cavitation

shared by Thijs Versloot on 27 Aug 14 - No Cached
annaheffernan liked it
  • Thijs Versloot on 27 Aug 14
     
    "A Soviet supercavitation torpedo called Shkval was able to reach a speed of 370km/h or more - much faster than any other conventional torpedoes," he said. However, The SCMP highlighted two problems in supercavitation technology. First, the submerged vessel needed to be launched at high speeds, approaching 100km/h, to generate and maintain the air bubble. Secondly, it is difficult if not impossible to steer the vessel using conventional mechanisms, which are inside the bubble, without direct contact with water. As a result, its application has been limited to unmanned vessels, fired in a straight line.
  • Paul N on 27 Aug 14
     
    can't you just selectively inject the gas so that you control in which direction the bubble forms?
johannessimon81

Google combines skycrane, VTOL and lifting wing to make drone deliveries - 6 views

www.wired.com/...ffort-to-build-delivery-drones

technology drone_delivery VTOL skycrane FUN soundtrack

shared by johannessimon81 on 30 Aug 14 - No Cached
annaheffernan liked it
  • johannessimon81 on 30 Aug 14
     
    Nice video featuring the technology. Plus it comes with a good soundtrack! Google's project wing uses a lifting wing concept (more fuel efficient than normal airplane layouts and MUCH more efficient than quadrocopters) but it equips the plane with engines strong enough to hover in a nose up position, allowing vertical landing and takeoff. For the delivery of packages the drone does not even need to land - it can lower them on a wire - much like the skycrane concept used to deliver the Curiosity rover on Mars. Not sure if the skycrane is really necessary but it is certainly cool. Anyways, the video is great for its soundtrack alone! ;-P
  • ...4 more comments...
  • Paul N on 31 Aug 14
     
    could we just use genetic algorithms to evolve these shapes and layouts? :P
  • Ma Ru on 31 Aug 14
     
    > Not sure if the skycrane is really necessary but it is certainly cool. I think apart from coolness using a skycrane helps keep the rotating knives away from the recipient...
  • Thijs Versloot on 01 Sep 14
     
    Honest question, are we ever going to see this in practice? I mean besides some niche application somewhere, isn't it fundamentally flawed or do I need to keep my window opened on the 3rd floor without a balcony when I ordered something from DX? Its pretty cool yes, but practical?
  • Guido de Croon on 02 Sep 14
     
    Package delivery is indeed more complicated than it may seem at first sight, although solutions are possible for instance by restricting delivery to distribution centers. What we really need of course is some really efficient and robust AI to navigate without any problems in urban areas : ) The hybrid is interesting since it combines the advantage of a Vertical Takeoff and Landing (and hover), and a wing for more efficient forward flight. Challenges lie in the control of the vehicle under any angle and all that this entails also for higher levels of control. Our lab has first used this concept a few years ago for the DARPA UAVforge challenge, and we had two hybrids in our entry last year for the IMAV 2013 (for some shaky images: https://www.youtube.com/watch?v=Z7XgRK7pMoU ).
  • Thijs Versloot on 04 Sep 14
     
    Fair enough, but even if you consider advanced/robust/efficient AI, why would you use a drone? Do we envision hundreds of drones above our heads in the street instead of UPS vans, or postmen, considering delivers letters might be more easily achievable. I am not so sure if personal delivery will take this route. On the other hand, if the system would work smoothly, I can image that I'm send a mail with the question whether I'm home (or they might know already from my personal GPS tracker) and then notify me that they are launching my DVD and it will come crashing into my door in 5min.
  • Paul N on 08 Sep 14
     
    I'm more curios how they're planning to keep people from stealing the drones. I could do with a drone army myself and having cheap amazon or google drones flying about sounds like a decent source.
Thijs Versloot

Active Metasurfaces for Advanced Wavefront Engineering #Harvard - 4 views

phys.org/...ces-grant-merge-classical.html

technology optics quantum metamaterials

shared by Thijs Versloot on 02 May 14 - No Cached
  • Thijs Versloot on 02 May 14
     
    Metasurfaces have been made, but the problem is that they usually are static and for quantum optic applications the question is how to make a rapidly configurable metasurface. for this Harvard has initiated a multidisciplinary team that involves theoretical physics, metamaterials, nanophotonic circuitry, quantum devices, plasmonics, nanofabrication, and computational modeling
  • Athanasia Nikolaou on 02 May 14
     
    Reading "wavefront engineering" in the title I thought it had to do with wave manipulation in the sea. Nothing to do though. As I read further in this article, Harvard thrives in forming multidisciplinarity groups. Their practice is to call the best team in each expertise they need to merge. Not one researcher from each discipline, but teams of experienced professors and a series of graduate students. Maybe we could discuss it in the retreat!
jessyjemy

What happens to your brain on the way to Mars - 1 views

advances.sciencemag.org/...e1400256

brain mars astronauts science technology space

shared by jessyjemy on 06 May 15 - No Cached
LeopoldS liked it
  • jessyjemy on 06 May 15
     
    This study from NASA shows that cosmic rays have a deleterious effect on the brain, more than expected, resulting in in symptoms similar to dementia (memory loss, decline in problem solving skills, general cognitive functions). A reason more to investigate into hibernation?
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