Tuesday, July 13. 2010
Velcro made from metal holds 35 tons per square meter
Via designboom
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'flamingo' fastener
photo credit: TUM
Hook and loop fasteners have become commonplace features of both industry and households.
However, they have one snag: they are too weak for many applications.hook and loop
fasteners made of spring steel have now been developed at the institute of metal forming and casting of the technische universitaet muenchen (TUM).
The device consists of hook tape and loop tape 0.2 mm thick. These fasteners are resistant to chemicals and can withstand a tensile load of up to 35 tonnes per square meter at temperatures as high as 800°C.
photo credit: TUM
spring steel hook elements deform elastically under light pressure to glide into openings in a perforated tape, once inserted, they return to their original form and resist back pull like an expanding rivet. Numerous steel hooks can attach at any angle to the loops in the perforated metal loop tape.
it can be mass-produced
photo credit: TUM
'metaklett' is a hook and loop fastener system developed by researchers at TUM,
the technische universitaet muenchen, under the leadership of professor hartmut
hoffmann (and as part of a joint project launched in 2005 with the federal ministry
of education and research / BMBF) in close cooperation with partners from industry.
'metaklett is a portmanteau of 'metall' and 'klettverschluss', which is the german generic
for velcro®. like velcro fasteners, 'metaklett' devices can be easy to secure and release,
yet they can withstand very strong mechanical stresses, high temperatures and harsh
chemicals. the unbeatable advantage of this hook and loop fastener is that it is easy
to close and open again, the principle therefore is put to a very wide range of uses,
for example air-conditioning and ventilation systems in building services engineering
and automotive construction.
hook HF 1 and loop LF1 combined
photo credit: TUM
the researchers created various three-dimensional models for the optimum interlocking of the fastener elements on the computer.they then built the most promising candidates as prototypes and subjected them to comprehensive tests. around 40 variations of the geometry referred to as 'flamingo' alone were tested on the computer. they studied its adhesive strength and reaction to extreme temperatures to establish the limits of its resilience.
'entenkopf" fastener
photo credit: TUM
a hybrid version with synthetic strap
photo credit: TUM
after testing, the institute settled on two variations: the 'flamingo' and 'entenkopf" (or duck's head) models. the hook forms of the two systems are vaguely reminiscent of a duck's head and a flamingo standing on one leg... the entenkopf uses fine steel hooks and loops, while the flamingo uses wider hooks that snap into openings in the tape. Depending on the direction of the applied force, this fastener can withstand a load of 7 to 35 newtons per square meter.
'entenkopf' fastener
photo credit: TUM
close-up of 'entenkopf' fastener
photo credit: TUM
a car parked in direct sunlight can reach temperatures of 80 °C, and temperatures of several hundred degrees centigrade can arise around the exhaust manifold. aggressive disinfectants are used for cleaning purposes in hospitals, and traditional hook, and loop fasteners are too weak for use in the construction of building façades...temperatures in excess and aggressive chemical solutions do not pose any problem for 'metaklett', which also offers adhesive strength of up to 35 tonnes per square meter when tensile force is applied parallel to the fastener surface. when it is applied perpendicular to the fastener surface, 'metaklett' can still withstand a force of seven tonnes per square meter, and, like a standard velcro® fastener, it can be opened and closed without the help of any tools.
up and close on velcro®
more than 60 years ago, the swiss engineer and inventor george de mestral was trying to painstakingly remove burrs from his dog's coat after a hunting excursion, he stumbled on an ingenious idea. based on the model he had observed in nature,he constructed a fastener from numerous small hooks and loops, which he subsequently named velcro®. unfortunately, standard synthetic hook and loop fasteners are not very resistant to heat and aggressive chemicals.
Is Symbian re-arranging the deck chairs on the Titanic?
Why Our Universe Must Have Been Born Inside a Black Hole
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"Accordingly, our own Universe may be the interior of a black hole existing in another universe." So concludes Nikodem Poplawski at Indiana University in a remarkable paper about the nature of space and the origin of time.
The idea that new universes can be created inside black holes and that our own may have originated in this way has been the raw fodder of science fiction for many years. But a proper scientific derivation of the notion has never emerged.
Today Poplawski provides such a derivation. He says the idea that black holes are the cosmic mothers of new universes is a natural consequence of a simple new assumption about the nature of spacetime.
Poplawski points out that the standard derivation of general relativity takes no account of the intrinsic momentum of spin half particles. However there is another version of the theory, called the Einstein-Cartan-Kibble-Sciama theory of gravity, which does.
This predicts that particles with half integer spin should interact, generating a tiny repulsive force called torsion. In ordinary circumstances, torsion is too small to have any effect. But when densities become much higher than those in nuclear matter, it becomes significant. In particular, says Poplawski, torsion prevents the formation of singularities inside a black hole.
That's interesting for a number of reasons. First, it has important implications for the way the Universe must have grown when it was close to its minimum size.
Astrophysicists have long known that our universe is so big that it could not have reached its current size given the rate of expansion we see now. Instead, they believe it grew by many orders of magnitude in a fraction of a second after the Big Bang, a process known as inflation.
The problem with inflation is that it needs an additional theory to explain why it occurs and that's ugly. Poplawski's approach immediately solves this problem. He says that torsion caused this rapid inflation.
That means the universe as we see it today can be explained by a single theory of gravity without any additional assumptions about inflation.
Another important by-product of Poplawski's approach is that it makes it possible for universes to be born inside the event horizons of certain kinds of black hole. Here, torsion prevents the formation of a singularity but allows a HUGE energy density to build up, which leads to the creation of particles on a massive scale via pair production followed by the expansion of the new universe.
This is a Big Bang type event. "Such an expansion is not visible for observers outside the black hole, for whom the horizon's formation and all subsequent processes occur after infinite time," says Poplawski.
For this reason, the new universe is a separate branch of space time and evolves accordingly.
Incidentally, this approach also suggests a solution to another of the great problems of cosmology: why time seems to flow in one direction but not in the other, even though the laws of physics are time symmetric.
Poplawski says the origin of the arrow of time comes from the asymmetry of the flow of matter into the black hole from the mother universe. "The arrow of cosmic time of a universe inside a black hole would then be fixed by the time-asymmetric collapse of matter through the event horizon," he says.
In other words, our universe inherited its arrow of time from its mother.
He says that daughter universes may inherit other properties from their mothers, implying that it may be possible to detect these properties, providing an experimental proof of his idea.
Theories of everything don't get much more ambitious than this. Entertaining stuff!
Ref: arxiv.org/abs/1007.0587: Cosmology With Torsion - An Alternative To Cosmic Inflation
Personal comment:
When science catches up to fiction (or not...)
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Comments
"Accordingly, our own Universe may be the interior of a black hole existing in another universe." So concludes Nikodem Poplawski at Indiana University in a remarkable paper about the nature of space and the origin of time."
Wow. The only thing remarkable about Nikodem Poplawski's paper is that such pseudoscientific hogwash can originate from an institution of higher learning in this day and age. I say, shame on the University of Indiana. The very idea of a black hole is based on the concept of continuity, an idea that is not only illogical (it leads to an infinite regress), but is not even scientific in the Popperian sense of falsification. Even Einstein, Mr. Continuity himself, had doubts about continuity.
Worst of all is the idea that somehow time has a direction of flow, i.e., an arrow. The idea that we are moving in time in one direction or another is a conceptual disaster. Why? Because time cannot change by definition. This is the reason that Karl Popper called spacetime "Einstein's block universe in which nothing happens" (source: Conjectures and Refutations). Absolutely nothing can move in spacetime for this reason. Why isn't Poplawski aware of this fact and how did his Star-Trek voodoo physics paper pass peer review? This is truly a sad commentary on the state of modern physics. This stuff is not even wrong.
The problem with the physics community is that theirs is an incestuous science that has been spawning hideous monstrosities for some time now. Their bunker mentality (the public is stupid and is the enemy) prevents them from considering other points of view, especially views that contradict their worldview. They have completely abandoned the search for a foundational understanding of nature and they insist on building up on their erroneous assumptions. Physicists do not even understand motion and yet they feel confident enough to create all sorts of silliness like wormholes, multiple universes and time travel. How dare they think that they are qualified to teach us about the origin of the universe when they are wallowing in ignorance about the most basic aspects of the universe?
Ask a physicist to explain why two bodies in relative inertial motion remain in motion and you'll come face to face with abject ignorance. Vast and profound ignorance is the norm in the physics community.
Let me add that I am deeply disappointed that publications like TR are still printing such pseudoscientific fairy tales under the banner of legitimate science. Paul Feyrabend was right when he wrote in Against Method, "[...]the most stupid procedures and the most laughable results in their domain are surrounded with an aura of excellence. It is time to cut them down in size, and to give them a more modest position in society." He might as well have been writing about physicists like Nikodem Poplawski.
Who will rise up to deliver us from this mountain of crap?