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santecarloni

Seismic Metamaterials Could Cloak Dams and Power Stations  - Technology Review - 2 views

www.technologyreview.com/...27566

metamaterial phy

shared by santecarloni on 17 Feb 12 - No Cached
  • santecarloni on 17 Feb 12
     
    Metamaterials that absorb seismic waves rather than steer them, might be a better way to protect some buildings, say engineers
  • ...1 more comment...
  • Luzi Bergamin on 18 Feb 12
     
    ???
  • LeopoldS on 21 Feb 12
     
    what are seismic metamaterials?
  • LeopoldS on 21 Feb 12
     
    must look funny ... They calculate the properties of such a metatmaterial and how it might be constructed with a basic repeating unit in the form of a concrete cylinder some 18 metres in diameter, with four perpendicular holes in its sides (see picture). These cylinders, perhaps varying in size to absorb a range of seismic wavelengths, would need to surround the foundations of a building in cylindrical shells some 60 metres across. That needn't be prohibitively expensive but it would be a big structure that could only be constructed around isolated buildings (thereby somewhat negating the supposed benefit that other buildings in the earthquake 'shadow' might also be protected).
pacome delva

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 !
santecarloni

Metamaterial switches on to the tune of light - physicsworld.com - 0 views

physicsworld.com/...itches-on-to-the-tune-of-light

technology PHY

shared by santecarloni on 24 Aug 12 - No Cached
  • santecarloni on 24 Aug 12
     
    An international team of researchers has created the first metamaterial where its properties can be controlled with light.
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 ...
Thijs Versloot

A microwave metamaterial with integrated power harvesting functionality - 3 views

scitation.aip.org/...1.4824473

metamaterials power sensor wifi

shared by Thijs Versloot on 04 Jul 14 - No Cached
LeopoldS liked it
  • Thijs Versloot on 04 Jul 14
     
    We present the design and experimental implementation of a power harvesting metamaterial. A maximum of 36.8% of the incident power from a 900 MHz signal is experimentally rectified by an array of metamaterial unit cells. We demonstrate that the maximum harvested power occurs for a resistive load close to 70 Ω in both simulation and experiment.
LeopoldS

Reconfigurable Electromagnetics Through Metamaterials-A Review - 5 views

ieeexplore.ieee.org/...abs_all.jsp

metamaterials

shared by LeopoldS on 26 May 15 - No Cached
  • LeopoldS on 26 May 15
     
    Interesting overview paper by Massa from Trient on reconfigurable metamaterials … makes me wonder if it is time for us to look closer into it or already too late …
pacome delva

Radiation fears stalk stellar mission - 0 views

physicsworld.com/...43063

space_mission GAIA solar_radiation

shared by pacome delva on 05 Jul 10 - Cached
  • Concern over ESA's handling of the radiation issue caused Michael Perryman, former GAIA project scientist, to resign from the agency in 2008. But GAIA science-team member Lennart Lindegren, an astronomer at Lund Observatory in Sweden, is confident that GAIA's unprecedented accuracy will be feasible. GAIA researchers will continue to perform tests and calibrations until at least 2011, which will include irradiating the CCDs at space-like temperatures. Lindegren admits, however, that they can never be certain of success until the spacecraft is in orbit and starts sending back data.
  • pacome delva on 05 Jul 10
     
    metamaterials to stop radiations?
  • LeopoldS on 05 Jul 10
     
    hmm ... in the optical range it is already a bit tricky .... lets brainstorm a bit about it ... anything in the literature? Luzi?
  • pacome delva on 06 Jul 10
     
    the components of the metamaterial need to have a size inversely proportional to the wavelenght, but here we are talking about high energy protons. So the idea was: is there metamaterials that change the electrical properties to solve this problem of holes in the material... but i dont have a clue !
pacome delva

Nanotube 'fuzz' boosts optical performance - 0 views

physicsworld.com/...42486

phy nan gold plasmonics metamaterials

shared by pacome delva on 29 Apr 10 - Cached
LeopoldS liked it
  • This structure is called a "plasmonic metamaterial" because its optical properties involve surface plasmons.
  • pacome delva on 29 Apr 10
     
    Again some plasmonic metamaterial...
dejanpetkow

Cloaking magnetic fields: First antimagnet developed - 2 views

www.sciencedaily.com/...110922192056.htm

superconductor metamaterial hybrid anti magnet

shared by dejanpetkow on 07 Oct 11 - No Cached
  • dejanpetkow on 07 Oct 11
     
    Sante, this thing is made of a superconductor-metamaterial hybrid. Should be non-linear enough for you :)
  • Luzi Bergamin on 08 Oct 11
     
    The device consists of a layer of superconducter, complemented by several layers of metamaterial. And the authors are afraid of potential abuse of this cloak to smuggle forbidden objets on airplanes etc. Hillarious! Another example how good research makes itself completely ridiculous by means of absurd claims about their potential usage.
johannessimon81

New Metamaterial Camera Has Super-Fast Microwave Vision - 1 views

www.wired.com/...new-metamaterial-camera

technology science PHY

shared by johannessimon81 on 18 Jan 13 - No Cached
LeopoldS liked it
  • johannessimon81 on 18 Jan 13
     
    "The metamaterial aperature is only 40 centimeters long and it doesn't move. It's a circuit-board-like structure consisting of two copper plates separated by a piece of plastic. One of the plates is etched with repeating boxy structures, units about 2 millimeters long that permit different lengths of microwaves to pass through. Scanning the scene at various microwave frequencies allows the computer to capture all the information necessary to reproduce a scene."
  • LeopoldS on 19 Jan 13
     
    where is Luzi's comment when one needs it ???
santecarloni

Was a metamaterial lurking in the primordial universe? - physicsworld.com - 1 views

physicsworld.com/...48238

CMB Universe PHY cosmology

shared by santecarloni on 05 Jan 12 - No Cached
  • santecarloni on 05 Jan 12
     
    A scientist in the US is arguing that the vacuum should behave as a metamaterial at high magnetic fields. Such magnetic fields were probably present in the early universe, and therefore he suggests that it may be possible to test the prediction by observing the cosmic microwave background (CMB) radiation - a relic of the early universe that can be observed today.
pacome delva

Metamaterials Probe Changes in Spacetime Structure | Physical Review Focus - 0 views

focus.aps.org/st6

phy metamaterials cosmology

shared by pacome delva on 24 Aug 10 - Cached
  • At the time of the big bang, our universe may not have had exactly three dimensions of space and one of time, according to some theorists. In the 6&nbsp;August Physical Review Letters, a team proposes a way to observe the postulated transition to our current universe using so-called metamaterials, structures in which the propagation of light can be precisely controlled. Experiments on such structures, they say, could test predictions that a "big flash" of radiation would accompany changes in the structure of spacetime that may have occurred in the early universe.
LeopoldS

Macroscopic invisibility cloaking of visible light : Nature Communications : Nature Pub... - 3 views

www.nature.com/...ncomms1176.html

invisibility PHY science

shared by LeopoldS on 02 Feb 11 - No Cached
  • LeopoldS on 02 Feb 11
     
    and all this without magic metamaterials ...
  • ...1 more comment...
  • Luzi Bergamin on 02 Feb 11
     
    Wellwellwell! I don't know how I have to complain, since I could not yet read the full article, but I'm sure I will :-).
  • Luzi Bergamin on 02 Feb 11
     
    It's funny to see how people get more and more humble in the desperate attempt to save their stupid ideas... At the beginning was the brave and bold aim to cloak something in free space (in a sphere or a cylinder). This requires inhomogeneous, anisotropic, magnetic materials; hopeless!! So one reduces to one polarization, now we have inhomogenous, anisotropic materials; still hopeless! At this point one downgraded the pretension: instead of cloaking in free space, we make a "carpet cloak" and hide an object behind an invisible dent in a mirror. But if that shall be continuous, we still need inhomogeneity and this is very hard. So now instead of a dent we take a cone and then it is claimed to work ... for ONE polarization. But of course the cloak can't work at all incident angles... irony of fate: everything is now made from birefringent media, the antithesis of what the metamaterials dogma was at the beginning!
  • jmlloren on 04 Feb 11
     
    Hi Luzi, can you please send me the paper. We are writing a project based on sulfates and carbonates, and all this BS sounds great for the introduction (The authors used Calcite as birefringent material)
santecarloni

How To Make A Metamaterial That Expands Under Pressure And Contracts In Tensi... - 0 views

www.technologyreview.com/...etamaterial-that-expands-under

technology science

shared by santecarloni on 12 Jul 12 - No Cached
  • santecarloni on 12 Jul 12
     
    Treating materials like complex networks leads to substances with extraordinary counterintuitive properties, say physicists
dejanpetkow

Metamaterials + Wireless Power Transfer - 2 views

www.sciencedaily.com/...140110153201.htm

technology science phy

shared by dejanpetkow on 21 Jan 14 - No Cached
LeopoldS liked it
  • dejanpetkow on 21 Jan 14
     
    Put together two ACT topics and see what happens.
  • LeopoldS on 22 Jan 14
     
    I remember discussing this briefly and then discarding the idea - but don't remember why any more; duncan?
  • Thijs Versloot on 23 Jan 14
     
    Well, I think that although the antenna is small, you counteract this with a much large metameterial lens. Probably if you design an antenna of a similar size to the 'lens' you can couple power equally well over the same distance. Then again, further optimization might help improve the size. Maybe in the end you want to combine both together, optimization of the antenna, including a metamaterials lens.
Marcus Maertens

World First: 3D Acoustic Cloaking Device | I Fucking Love Science - 1 views

www.iflscience.com/...st-3d-acoustic-cloaking-device

PHY science

shared by Marcus Maertens on 14 Mar 14 - No Cached
  • Marcus Maertens on 14 Mar 14
     
    Old news... Sante was doing this 10 years ago! And why does their metamaterial look like a pyramid?
  • johannessimon81 on 14 Mar 14
     
    According to Terry Pratchett pyramids affect the flow of time. Using this, any kind of cloaking device should be trivial.
H H

Temporal cloacking without metamaterials - 0 views

arxiv.org/1308.2606v1

shared by H H on 14 Aug 13 - No Cached
  • H H on 14 Aug 13
     
    We propose a way of implementing an event cloaking device without the use of metamaterials. Rather than slowing down and speeding up light, we manipulate an obscurity gap by diverting the light through paths of appropriate length with an arrangement of switchable transreflective mirrors.
Thijs Versloot

Infinite phase velocity in zero permittivity #metamaterial achieved - 2 views

phys.org/...sible-infinite-wavelength.html

light nano metamaterials

shared by Thijs Versloot on 14 Oct 13 - No Cached
  • johannessimon81 on 14 Oct 13
     
    Damn... At Leiden University I worked on transmission of light through Ag nano-layers. This could have been an easy experiment. I wonder about the evanescence of the wave as visible light is usually attenuated to <5% within 250nm of silver.
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!
jcunha

Researchers design metamaterial that buckles selectively - 4 views

phys.org/...5-06-metamaterial-buckles.html

PHY space FUN buckling 3D-print

shared by jcunha on 11 Jun 15 - No Cached
  • jcunha on 11 Jun 15
     
    New 3D printed macro structure exhibits selective buckling open the way for custom shape-memory materials found our neighbor scientists from the Lorentz Institut of the Leiden University. Wonder if it can be applied for self-assembled deployment of structures.
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