#Introducing a New Material for Invisibility Cloaks Unless youe a teenage wizard, making things invisible involves some challengesloaking devices tend to be bulky
Researchers at the University of California, San diego, designed a carpet cloak, a device that covers an object and scatters light
as if it hitting a flat surface instead of something three-dimensional. The cloak is very thinnly about a tenth the size of the wavelength of the photons it scatteringnd lossless
Instead of a periodic structure of metal, which absorbs light, they use two dielectric materials, a Teflon substrate studded with cylinders made of a ceramic.
The ceramic has a high refractive index, and the Teflon has a low refractive index. When combined, they create a metamaterial, capable of bending light in unusual ways.
The team also varied the height of the cylinders by a small amount, in a pattern devised by their computer.
The different heights change the phase of the light bouncing off different parts of the cloak to mimic the phase it would have
if it were bouncing off a flat surface. Despite the effect of those height differences, the thicknesses involved are so tiny that the researchers consider this a two-dimensional metasurface,
a newer version of metamaterials that has generated recently some interest. ne tenth of the wavelength is essentially like 0 in height,
says Boubacar Kante, assistant professor of electrical and computer engineering at UCSD, who led the work, which appears in the latest issue of Progress in Electromagnetics Research.
This particular cloak exists only in computer simulation, though the team is working on building a physical version,
Kante says. It was designed for the microwave range with a 0. 6 cm thickness to handle 6 cm wavelengths, simply because those larger dimensions made it easier to work with.
A cloak could be made for visible light but would have to be much thinner. Because the shortest wavelength the human eye perceives is slightly less than 400 nm,
a cloak would have to be less than 40 nm thick, a dimension easily achievable by the photolithography processes used for making computer chips.
But Kante points out that microwave cloaks could be useful for the military, to hide objects from radar working at such wavelengths.
One tradeoffhe range of wavelengths covered is very narrow. Changing the design to cover a broader range makes the material more lossy.
Kante says the design might have other uses besides invisibility. For instance, it could shield antennas in cell towers from each other, lowering crosstalk.
Or it could make better solar concentrators, which focus sunlight to run steam turbines
#Wind turbines Power Liquid-air Energy storage One startup energy company is looking to reinvent not only wind energy, but also energy storage.
Keuka Energy recently launched a 125-kilowatt prototype vessel that uses its novel floating wind turbine design paired with liquid-air energy storage to create a steady source of electricity.
Unlike traditional wind turbines, which have three blades and a central gearbox, Keuka turbine is a pinwheel of aluminum blades that sits atop a floating V-shape platform containing liquid air.
The Florida-based company claims that its wind turbine design allows for larger turbines that could produce far more electricity.
The world largest single offshore wind turbine is currently about 6 megawatts; Keuka says its full-size turbines could produce at least double that amount.
Liquid-air energy storage, also sometimes called cryogenic energy storage, is a long-term energy storage method: electricity liquefies air to nearly-200°C and then stores it at low pressure.
When the energy is needed, the liquid air is pumped to a high level of pressure and heated to a gas state.
The gas then drives a turbine. Although it is an attractive energy storage technology because of its long duration,
liquid-air energy storage requires a significant amount of electricity to make the liquid air, limiting its usage by utilities.
Keuka claims that because its design substantially reduced the cost by supplying the power directly from the turbines to the liquefaction equipment.
The company also says its wind turbine design is more cost effective thanks to elimination of the gear box and the use of lightweight aluminum blades that cost less than 10 percent the price of traditional composite blades.
Even if the technology is effective and can come in at lower costs, Keuka will likely face a long road to acceptance by the notoriously risk averse utility industry.
Keuka is not the only startup looking to advance liquid-air energy storage. In 2014, General electric signed an exclusive global licensing deal with Highview Power storage,
a U k. startup that makes utility-scale liquid-air energy storage systems. Another similar technology that has gained more traction is compressed-air energy storage
which does not have the energy density of liquid air, but so far has proven more cost effective.
Compressed air, while a cheap form of energy storage once built, is still expensive to build and geographically limited;
underground caverns are needed to store the air. Other startups are also looking offshore for cheap energy storage.
Bright Energy is developing a system that would use offshore renewable energy to store compressed air in vessels in the ocean.
Canadian startup Hydrostor also has a design to store compressed air underwater. If Keuka 125-kilowatt prototype is successful,
it plans to launch a larger 25 MW demonstration project in early 2017 1
#Why Aren't Supercomputers Getting Faster Like They Used To? Currently, the world most powerful supercomputers can ramp up to more than a thousand trillion operations per second,
or a petaflop. But computing power is not growing as fast as it has in the past.
On Monday, the June 2015 listing of the Top 500 most powerful supercomputers in the world revealed the beginnings of a plateau in performance growth.
There are a number of technical aspects and economic factors that interfere with supercomputing improvements. Experts disagree on the cause,
but the result could be a slowing of the pace of improvement in some scientific fields.
Computing hardware development projections are based on Moore Law which predicts that the number of transistors on integrated circuits will double about every two years, causing an exponential growth in performance.
Supercomputer power is expected, for the most part to follow the same curve. In the past, that was exactly the case.
The rate of performance developmenthe change in aggregate number of petaflops between Top500 listsad doubled each year.
But in the past few years, each new annual total has been only 1. 5 times as great as the one preceding it.
The development rate began tapering off around 2008. Between 2010 and 2013, aggregate increases ranged between 26 percent and 66 percent.
And on this June list there was a mere 17 percent increase from last November. e were aiming for 2020,
but it may not be till 2023 when we reach exascale computational ratesack Dongarra, Oak ridge National Laboratory What behind the trend?
One reason, says IBM senior manager of Data Centric Systems, John Gunnels, is that the pace of Moore Law has slowed. f you can shrink these chips at the rate you were shrinking them before,
then you aren going to get that doubling of computational power. The semiconductor industry seems to be reaching the limits of its ability to shrink chips using conventional chip technology.
IBM researchers are trying to prop up Moore law using silicon-germanium transistor channels in effort to create a 7-nanometer chip within the next four years.
The cost of the electricity to power these behemoths has played also a role in slowing the speed of supercomputer development. an somebody make a computer that has higher performance?
asks Gunnels. robably. But it would take a lot more money and power than someone would be willing to supply.
According to Jack Dongarra, one of the curators of the Top500 list and a faculty member at the University of Tennessee and Oak ridge National Laboratory, Moore Law is not the problem. ome people think it the end of Moore Law,
but I don think that true, he says. t comes down to money. It not a question of anything else but funding.
Other laboratories could reach the performance of the number one supercomputer, Tianhe-2 if they want to pay US $390 million for the same technology,
he points out. Dongarra predicts that the China Tianhe-2 will remain at the top of the supercomputer pyramid for at least two more lists because of the lack of funding for new systems.
Despite the slowdown, many computational scientists expect performance to reach exascale, or more than a billion billion operations per second, by 2020.
But the actual trend depicts a different story. e were aiming for 2020, but it may not be till 2023
when we reach exascale computational rates, Dongarra says. Though computer scientists in the United states say 2023 is a more feasible timeline to construct an exascale supercomputer
(and the U s. government is planning out an exascale supercomputer that would cost $200 million),
institutions in China and Japan are determined to reach this computational milestone by 2020. In the meantime, this recent period of apparent stagnation could impact the many fields that rely on supercomputing,
such as weather projection. he National Weather Service uses supercomputers to run physical models to predict what will happen in three to five days,
says Dongarra. igger and faster computers will make those predictions better. r
#Diesel-Powered Fuel cell Produces Clean electricity Although several options to store hydrogen as a fuel for cars have been investigated,
a practical and affordable way to store and distribute hydrogen is still the biggest hurdle to the wide deployment of green, CO2 EMISSION-free cars.
Now researchers in Europe have built a demonstration system that might be a first step in circumventing the limitations on hydrogen distribution and storage;
they simply extract hydrogen from diesel fuel on the go. The research group,"Fuel cell Based Power Generation (FCGEN),
"which includes researchers from Volvo Technology (Sweden), Johnson-Matthey (United kingdom), Modelon AB (Sweden), Powercell AB (Sweden), Jo ef Stefan Institute (Ljubljana, Slovenia), Forschungszentrum
Jülich (Germany) and Fraunhofer ICT-IMM (Mainz, Germany) announced in a recent press release the creation of a prototype 3-kilowatt,
diesel-fueled fuel cell system that has operated flawlessly for 10,000 hours. The extraction of the hydrogen from the diesel fuel happens through autothermal reforming, a catalytic reaction in
which the diesel fuel is decomposed into hydrogen, steam, carbon dioxide, and carbon monoxide. The CO is converted then to CO2
"The researchers say that the system could generate between 3 and 10 kw of power in trucks;
In addition to lowering CO2 EMISSION, the units produce little noise, making them suitable as mobile electricity generators in places, like field hospitals,
#Asteroid mining Firm's First Spacecraft Deploys from Space station Last week, the first in a line of spacecraft designed to test technologies needed to eventually mine asteroids launched from the International space station.
asteroid mining firm Planetary Resources, aims to test critical electronic systems and software during its 90-day mission.
having arrived at the ISS thanks to a Spacex Falcon 9 rocket launched in April. ur team is developing the technology that will enable humanity to create an off-planet economy that will fundamentally change the way we live on Earth,
The asteroid mining firm formed in 2012 with the purpose of figuring out an economical way to mine platinum
palladium, or rare earth materials from near-Earth asteroids. Prominent billionaire backers include Hollywood director James cameron and Google executives Larry page and Eric Schmidt.
But the exact mineral wealth of the asteroids most easily accessible from Earth remains unknown.
Indeed, a Harvard university study found just 10 nearby asteroids worth mining. Planetary Resourcesext demonstrator, called the Arkyd-6 (A6),
is scheduled to test the ext generation of attitude control, power, communication, and avionics systemsalong with sensors that can analyze asteroids for the resources they contain.
Such sensors include a mid-wave infrared imaging system capable of measuring temperature differences on observed objects
and obtaining data on the presence of water or water-rich minerals. The A6 is scheduled to launch sometime later this year Planetary Resources says it wants to pursue a est oftenphilosophy in building the A3r
and successive generations of spacecraft. e are innovating on every level from design to launch,
and the others that we manufacture using 3-D printers. t
#Nanowires Boost Hydrogen Production from Sunlight Tenfold Using the energy of the sun to split water into hydrogen
and oxygen gives you access to a completely carbon-free energy source for transportation. But so far, the efficiency of the process has been a bit disappointing,
even when using systems called solar fuel cells solar cells immersed in the water it splitting. Now researchers from Eindhoven University of Technology in The netherlands and the Dutch Foundation for Fundamental Research on Matter (FOM) report in the 17 july issue of Nature Communications that they have improved tenfold the hydrogen producing capacity of a solar fuel cell.
The key was to use a photocathodehe electrode that supplies electrons when illuminated by sunlightade from an array of gallium phosphide nanowires.
Previously, researchers used flat surfaces of the semiconductor gallium phosphide as the photocathode, but light absorption was low.
The Gap nanowires, about 500 nm long and 90 nm thick, increased enormously the surface of the photocathode exposed to light.
By adding platinum particles, its catalytic properties improved hydrogen production even more, report the researchers. At the same time, the nanowires allowed a drastic reduction in the use of Gap material
. or the nanowires we needed ten thousand times less precious Gap material than in cells with a flat surface.
That makes these kinds of cells potentially a great deal cheaper said Erik Bakkers of Eindhoven University of Technology,
as quoted in a press release. n addition, Gap is also able to extract oxygen from the watero you then actually have a fuel cell in
which you can temporarily store your solar energy. In short, for a solar fuels future we cannot ignore gallium phosphide any longer,
he added. i
#Porous Silicon Battery electrodes from Reeds Natural structures in reed leaves could find use in advanced lithium-ion batteries,
which could lead to a more sustainable way to create sophisticated energy storage devices, scientists in China and Germany say.
Silicon-based materials can theoretically store more than 10 times charge than the carbon-based materials most commonly used in the anodes of commercial lithium-ion batteries,
making them promising next-generation anode materials. However, silicon big problem is that it can swell by more than 300 percent
when filled with lithium. The constant swelling and shrinking as the battery charges and discharges
causes the anode to crack. One way to overcome this problem is to make silicon porous enough to accommodate the expansion.
But synthesizing these structures is commonly a complex, energy-intensive, and costly process. Now scientists have developed 3-D porous silicon-based anode materials using the kind of reed leaves that are abundant in temperate wetlands.
Reeds naturally absorb silica from the soil, which accumulates in sheetlike structures around micro-compartments in the plants.
The researchers took common reeds from southwest Germany, dried them at high temperatures, purified them with hydrochloric acid,
and made them into silicon-based anodes by heating them with magnesium and coating them with carbon.
Although the 3-D structures of the leaves shrunk the resulting material preserved the natural architecture found in the reeds.
After 200 cycles of charging and discharging, these anodes could store nearly three times more charge than carbon-based anodes;
after 4, 000 such cycles, although the amount of charge they could store diminished substantially,
they could still store more than 15 percent more than carbon-based anodes. The scientists detailed their findings online 26 june in the journal Angewandte Chemie International Edition l
#System Does occupied Wi-fi in TV Channels Internet providers have been hoping to get their hands on precious low frequency UHF channels unused by broadcast TV.
But maybe they can share those that are still in use. Engineers at Rice university in Houston, Tex.
created the first device that allows Wireless internet in a UHF channel that is already occupied by a TV broadcast. nstead of all television or all wireless connection,
Edward Knightly, Rice university Sending wireless data through this 400 megahertz to 700 MHZ slice of spectrum is referred often to as uper Wi-Fibecause of its ability to penetrate through buildings and travel long distances.
Such superpowers could allow Internet coverage in secluded areas that traditional terrestrial broadband cannot economically reach.
However, unused UHF channels, commonly referred to as TV white-spaces, are scarce. In big cities such as Houston, where the study was conducted,
In New york and Los angeles there are none. nstead of all television or all wireless connection how can we do both?
the professor of electrical and computer engineering who led the research. The Rice university engineers called their answer i-Fi in Active TV Channels or WATCH.
They had to gain approval from the U s. Federal Communications Commission to test it. The WATCH spectrum sharing system works on a feedback loop.
It is continuously watching for whenever a viewer is not watching a TV channel. The system consists of a special Wi-fi transmitter
and a receiver in a person home and requires a smart TV. The system could deliver 6 times as much data as white space schemes in use today Currently
TV towers occupy a whole channel no matter how many viewers are watching at a given time,
says one of the study researchers, Xu Zhang. ven though these channels are being occupied by TV broadcasters most people use cable, satellite,
or Internet to watch television, he says. hat means these TV broadcasters are wasting spectrum.
But under the WATCH system, a user TV viewing information is sent to a spectrum database by smartphone remote control and smart TV.
This database updates the WATCH receiver telling it that it can cancel out the TV broadcast
and use the channel to send data via the WATCH transmitter. If the viewer flips back to that channel
another signal is sent to the spectrum database, updating the WATCH system. The system then would move its data stream to a different channel to keep from interfering with the user TV viewing experience.
WATCH also takes into consideration what channels neighbors are watching, so Wi-fi streaming doesn interfere with their TV signal,
says Zhang. If a next door neighbor wants to watch the channel WATCH is using to stream Wi-fi,
then the system will locate and use channel that has no nearby viewers. The engineers found that their system could provide six times as much wireless data4 megabits per seconds TV white-space systems in use today
which only utilize unoccupied UHF channels. he system provides a step towards improved utilization of UHF frequency bands,
says Knightly. here are implications that this could allow Wireless internet access in difficult to reach places and underserved areas.
Wireless companies, such as Carlson Wireless Technologies, are already looking to UHF channels to provide connectivity in underdeveloped countries.
There is a much larger need for Internet connectivity than television in developing countries, says James Carlson,
founder and CEO of Carlson Wireless Technologies. eople would rather leapfrog technology that will soon be obsolete.
Carlson Wireless plans to deploy 3-G wireless service over TV white-space in Africa and parts of South and Southeast asia later this year
and in the United states in 2016. For WATCH use in the United states, he biggest challenge is getting FCC approval,
says Knightly. his particular solution requires FCC collaboration in order to deploy it. e
#Stretchable Conducting Fiber Provides Super Hero Capabilities The list of potential applications for a new electrically conducting fiberrtificial muscles,
exoskeletons and morphing aircraftounds like something out of science fiction or a comic book. With a list like that, it got to be a pretty special fiberand it is.
The fiber, made from sheets of carbon nanotubes wrapped around a rubber core, can be stretched to 14 times its original length
and actually increase its electrical conductivity while being stretched, without losing any of its resistance. An international research team based at the University of Texas at Dallas initially targeted the new super fiber for artificial muscles and for capacitors
whose storage capacity increases tenfold when the fiber is stretched. However the researchers believe that the material could be used as interconnects in flexible electronics and a host of other related applications.
In research published in the journal Science, the team describes how they devised a method for wrapping electrically conductive sheets of carbon nanotubes around the rubber core in such a way that the fiber's resistance doesn change when stretched,
but its conductivity increases. e make the inelastic carbon nanotube sheaths of our sheath-core fibers super stretchable by modulating large buckles with small buckles,
so that the elongation of both buckle types can contribute to elasticity, said Ray Baughman, senior author of the paper and director of the Alan G. Macdiarmid Nanotech Institute at UT Dallas,
in a press release. hese amazing fibers maintain the same electrical resistance, even when stretched by giant amounts,
because electrons can travel over such a hierarchically buckled sheath as easily as they can traverse a straight sheath.
The researchers have also been able to add a thin coat of rubber to the sheath-core fibers
and then another carbon nanotube sheath to create strain sensors and artificial muscles. In this setup, the buckled nanotube sheets act as electrodes
and the thin rubber coating serves as the dielectric. Voilà! You have a fiber capacitor. his technology could be well-suited for rapid commercialization,
said Raquel Ovalle-Robles, one of the paper authors, in the press release. he rubber cores used for these sheath-core fibers are inexpensive and readily available.
The only exotic component is the carbon nanotube aerogel sheet used for the fiber sheath
#The First White Laser Scientists and engineers at Arizona State university, in Tempe, have created the first lasers that can shine light over the full spectrum of visible colors.
The device inventors suggest the laser could find use in video displays, solid-state lighting, and a laser-based version of Wi-fi. Although previous research has created red, blue, green and other lasers,
each of these lasers usually only emitted one color of light. Creating a monolithic structure capable of emitting red, green,
and blue all at once has proven difficult because it requires combining very different semiconductors. Growing such mismatched crystals right next to each other often results in fatal defects throughout each of these materials.
But now scientists say theye overcome that problem The heart of the new device is a sheet only nanometers thick made of a semiconducting alloy of zinc, cadmium, sulfur, and selenium.
The sheet is divided into different segments. When excited with a pulse of light, the segments rich in cadmium and selenium gave off red light;
those rich in cadmium and sulfur emitted green light; and those rich in zinc and sulfur glowed blue.
The researchers grew this alloy in stages, carefully varying the temperature and other growth conditions over time.
By controlling the interplay between the vapor, liquid, and solid phases of the different materials that made up this nanosheet,
they ensured that these different crystals could coexist. The scientists can individually target each segment of the nanosheet with a light pulse.
Varying the power of the light pulses that each section received tuned how intensely they shone,
allowing the alser to produce 70 percent more perceptible colors than the most commonly used light sources.
Lasers could be far more energy-efficient than LEDS: While LED-based lighting produces up to about 150 lumens per watt of electricity,
lasers could produce more than 400 lumens per watt, says Cun-Zheng Ning, a physicist and electrical engineer at Arizona State university at Tempe who worked on the laser.
In addition, he says that white lasers could also lead to video displays with more vivid colors and higher contrast than conventional displays.
Another important potential application could be"Li-Fi, "the use of light to connect devices to the Interenet.
Li-Fi ould be 10 times faster than today Wi-fi, but"the Li-Fi currently under development is based on LEDS,"
"Ning says. He suggests white-laser based Li-Fi could be 10 to 100 times faster than LED-based Li-Fi,
because the lasers can encode data much faster than white LEDS. In the future, the scientists plan to explore
whether they can excite these lasers with electricity instead of with light pulses. They detailed their findings online 27 july in the journal Nature Nanotechnology N
#Spintronic Devices Possible Without Magnetic material Spintronics, which has offered a promising alternative to electronics, may have just been given a boost that moves it from mere promise to likely future backbone of computing.
A young researcher at Argonne National Laboratory has stumbled upon the amazing discovery that a magnetic material may not be required
in order to generate spin current from insulators. The implications of this discovery, which are described in the journal Physical Review Letters,
could be far reaching and make possible the continued trend towards ever more powerful computing. his is a discovery in the true sense,
said Anand Bhattacharya, a physicist in Argonne's Materials science Division and the project's principal investigator,
in a press release. here no prediction of anything like it. The hope of spintronics stems from its use of the spin of electrons to encode information rather than the transport of electrical charge of electrons.
This fundamental difference is believed to be a solution to many of the problems associated with electronics,
such as high power consumption and the need for more space on a chip. To date, to be able read the spin of the electrons,
which is either por own, electrons have had to be held in place in a ferromagnetic insulator material, like yttrium iron garnet (YIG.
With the electrons held up momentarily, a heat gradient is applied to the material to set the spin of the electrons in motion again.
Once they are spinning across the lattice of the crystal insulator, they start communicating information about the orientation of their spin.
In this way, just like an electrical current is a stream of electrons moving through a conductor,
a current of pure spin can be achieved in magnetic insulators. Stephen Wu, the postdoctoral researcher who made the discovery,
was looking at different materials that would make it possible to produce smaller spintronic devices and provide greater control over the thermal gradients that needed to be applied to the material to start the current spin of the electrons.
It was during this experimentation with different materials that Wu found himself working with YIG on a substrate of paramagnetic gadolinium gallium garnet (GGG.
because the paramagnet doesn generate a magnetic field. he spins in the system were not talking to each other.
the researchers see an opportunity to push ahead the state-of-the-art in spintronics. ee just taken ferromagnetism off its pedestal,
said Wu in the release. n a spintronic device you don have to use a ferromagnet.
You can use either a paramagnetic metal or a paramagnetic insulator to do it now. c
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