GES Mk 54 Mod 1 Dispozitiv de ardere cu sistem dual inițiator, care nu arată la fel de elegant ca Pandora
o tehnologie care permite obiectelor să devină invizibile sau nedetectabile undelor electromagnetice, inclusiv undele radio, Microunde, infraroșu și lumină vizibilă.Mantalele sunt fabricate din materiale artificiale, numite metamateriale, care au proprietăți speciale care permit un control mai bun al undelor de intrare și pot face un obiect invizibil sau transparent. Limitele nou stabilite se aplică pe mantalele fabricate din metamateriale pasive – cele care nu atrag energia de la o sursă de energie externă.
| Posted: Jul 06, 2016 | |
Researchers determine fundamental limits of invisibility cloaks(Nanowerk News) Researchers in the Cockrell School of Engineering at The University of Texas at Austin have been able to quantify fundamental physical limitations on the performance of cloaking devices, a technology that allows objects to become invisible or undetectable to electromagnetic waves including radio waves, microwaves, infrared and visible light. |
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| The researchers’ theory confirms that it is possible to use cloaks to perfectly hide an object for a specific wavelength, but hiding an object from an illumination containing different wavelengths becomes more challenging as the size of the object increases. | |
| Andrea Alù, an electrical and computer engineering professor and a leading researcher in the area of cloaking technology, along with graduate student Francesco Monticone, created a quantitative framework that now establishes boundaries on the bandwidth capabilities of electromagnetic cloaks for objects of different sizes and composition. As a result, researchers can calculate the expected optimal performance of invisibility devices before designing and developing a specific cloak for an object of interest. Alù and Monticone describe their work in the journal Optica („Invisibility exposed: physical bounds on passive cloaking”). | |
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| The graph shows the trade-off between how much an object can be made transparent (scattering reduction; vertical axis) and the color span (bandwidth; horizontal axis) over which this phenomenon can be achieved. The red line represents the optimal performance achievable by a passive cloak, dividing the graph in realizable and forbidden regions. No passive invisibility device can attain performance values belonging to the forbidden region. Achieving invisibility becomes more and more challenging for bigger objects (the red line representing the bound moves upward and to the left, as indicated by the arrow). (Image: Cockrell School of Engineering) | |
| Cloaks are made from artificial materials, called metamaterials, that have special properties enabling a better control of the incoming wave, and can make an object invisible or transparent. The newly established boundaries apply to cloaks made of passive metamaterials – those that do not draw energy from an external power source. | |
| Understanding the bandwidth and size limitations of cloaking is important to assess the potential of cloaking devices for real-world applications such as communication antennas, biomedical devices and military radars, Alù said. The researchers’ framework shows that the performance of a passive cloak is largely determined by the size of the object to be hidden compared with the wavelength of the incoming wave, and it quantifies how, for shorter wavelengths, cloaking gets drastically more difficult. | |
| For example, it is possible to cloak a medium-size antenna from radio waves over relatively broad bandwidths for clearer communications, but it is essentially impossible to cloak large objects, such as a human body or a military tank, from visible light waves, which are much shorter than radio waves. | |
| „We have shown that it will not be possible to drastically suppress the light scattering of a tank or an airplane for visible frequencies with currently available techniques based on passive materials,” Monticone said. „But for objects comparable in size to the wavelength that excites them (a typical radio-wave antenna, for example, or the tip of some optical microscopy tools), the derived bounds show that you can do something useful, the restrictions become looser, and we can quantify them.” | |
| In addition to providing a practical guide for research on cloaking devices, the researchers believe that the proposed framework can help dispel some of the myths that have been developed around cloaking and its potential to make large objects invisible. | |
| „The question is, ‘Can we make a passive cloak that makes human-scale objects invisible?’ ” Alù said. „It turns out that there are stringent constraints in coating an object with a passive material and making it look as if the object were not there, for an arbitrary incoming wave and observation point.” | |
| Now that bandwidth limits on cloaking are available, researchers can focus on developing practical applications with this technology that get close to these limits. | |
| „If we want to go beyond the performance of passive cloaks, there are other options,” Monticone said. „Our group and others have been exploring active and nonlinear cloaking techniques, for which these limits do not apply. Alternatively, we can aim for looser forms of invisibility, as in cloaking devices that introduce phase delays as light is transmitted through, camouflaging techniques, or other optical tricks that give the impression of transparency, without actually reducing the overall scattering of light.” | |
| Alù’s lab is working on the design of active cloaks that use metamaterials plugged to an external energy source to achieve broader transparency bandwidths. | |
| „Even with active cloaks, Einstein’s theory of relativity fundamentally limits the ultimate performance for invisibility,” Alù said. „Yet, with new concepts and designs, such as active and nonlinear metamaterials, it is possible to move forward in the quest for transparency and invisibility.” |
| Source: University of Texas at Austin |
Read more: Researchers determine fundamental limits of invisibility cloaks
intensă.
Prin schimbarea dimensiunilor nano-sferelor de pornire, se reflectă diferite culori (sau lungimi de undă) de lumină. Și deoarece materialul are o consistență asemănătoare cauciucului, atunci când este răsucite și întinse, distanța dintre sfere se schimbă, determinând materialul să schimbe culoarea. Când este întins, materialul se deplasează în gama albastră a spectrului, iar când este comprimat, culoarea se schimbă spre roșu. Când este eliberat, materialul revine la culoarea inițială. Astfel de materiale de chameleon s-ar putea să-și găsească drumul în imagini de fundal care schimbă culoarea sau în straturile de acoperire care reflectă radiația termică infraroșie.
| Posted: Jun 03, 2016 | |
Squeezing out opal-like colors by the mile (w/video)(Nanowerk News) The team, led by the University of Cambridge, have invented a way to make such sheets on industrial scales, opening up applications ranging from smart clothing for people or buildings, to banknote security. |
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| Using a new method called Bend-Induced-Oscillatory-Shearing (BIOS), the researchers are now able to produce hundreds of metres of these materials, known as ‘polymer opals’, on a roll-to-roll process. The results are reported in the journal Nature Communications („Large-scale ordering of nanoparticles using viscoelastic shear processing”). | |
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| Researchers at the University of Cambridge have devised a method to produce „Polymer Opals” on an industrial scale. | |
| Some of the brightest colours in nature can be found in opal gemstones, butterfly wings and beetles. These materials get their colour not from dyes or pigments, but from the systematically-ordered microstructures they contain. | |
| The team behind the current research, based at Cambridge’s Cavendish Laboratory, have been working on methods of artificially recreating this ‘structural colour’ for several years, but to date, it has been difficult to make these materials using techniques that are cheap enough to allow their widespread use. | |
| In order to make the polymer opals, the team starts by growing vats of transparent plastic nano-spheres. Each tiny sphere is solid in the middle but sticky on the outside. The spheres are then dried out into a congealed mass. By bending sheets containing a sandwich of these spheres around successive rollers the balls are magically forced into perfectly arranged stacks, by which stage they have intense colour. | |
| By changing the sizes of the starting nano-spheres, different colours (or wavelengths) of light are reflected. And since the material has a rubber-like consistency, when it is twisted and stretched, the spacing between the spheres changes, causing the material to change colour. When stretched, the material shifts into the blue range of the spectrum, and when compressed, the colour shifts towards red. When released, the material returns to its original colour. Such chameleon materials could find their way into colour-changing wallpapers, or building coatings that reflect away infrared thermal radiation. | |
| A synthetic material which mimics the brightest and most vivid colours in nature, and changes colour when twisted or stretched, has been developed by researchers at the University of Cambridge, and could have important applications in the security, textile and sensing industries. The Polymer Opal films change to green and blue when stretched, and to red when compressed. | |
| „Finding a way to coax objects a billionth of a metre across into perfect formation over kilometre scales is a miracle,” said Professor Jeremy Baumberg, the paper’s senior author. „But spheres are only the first step, as it should be applicable to more complex architectures on tiny scales.” | |
| In order to make polymer opals in large quantities, the team first needed to understand their internal structure so that it could be replicated. Using a variety of techniques, including electron microscopy, x-ray scattering, rheology and optical spectroscopy, the researchers were able to see the three-dimensional position of the spheres within the material, measure how the spheres slide past each other, and how the colours change. | |
| „It’s wonderful to finally understand the secrets of these attractive films,” said PhD student Qibin Zhao, the paper’s lead author. | |
| Cambridge Enterprise, the University’s commercialisation arm which is helping to commercialise the material, has been contacted by more than 100 companies interested in using polymer opals, and a new spin-out Phomera Technologies has been founded. Phomera will look at ways of scaling up production of polymer opals, as well as selling the material to potential buyers. Possible applications the company is considering include coatings for buildings to reflect heat, smart clothing and footwear, or for banknote security and packaging applications. |
| Source: University of Cambridge |
Read more: Squeezing out opal-like colors by the mile (w/video)
Ca o soluție, echipa coreeană de cercetare, care include în continuare profesorii Sung-Yool Choi (Inginerie electrică) și Taek-Soo Kim (Ingineria mecanică) a KAIST și studenții lor, a propus o nouă arhitectură a dispozitivelor care poate maximiza eficiența bazată pe grafen OLED – uri. Ei au fabricat un anod transparent într – o structură compozită în care un TiO 2 straturi , cu un indice ridicat de refracție (high n) și un strat gaură de injecție (HIL) de polimeri conductori , cu un indice de refracție scăzut (low-n) electrozi tip sandwich grafenice . Acesta este un design optic care induce o colaborare sinergică între nivelele înalte n și joase-n pentru a crește reflexia efectivă a TE. Ca rezultat, amplificarea rezonanței cavității optice este maximizată. Rezonanța cavității optice este legată de îmbunătățirea eficienței și a gamei de culori în OLED-urile. În același timp, pierderea de la polaritonul de suprafață a plasmonului (SPP), o cauză majoră pentru emisiile slabe de fotoni în OLED-uri, este de asemenea redusă datorită prezenței polimerilor cu conductivitate joasă.
Read more: Graphene-based transparent electrodes for highly efficient flexible OLEDS
| Posted: Jun 03, 2016 | |
Graphene-based transparent electrodes for highly efficient flexible OLEDS(Nanowerk News) The arrival of a thin and lightweight computer that even rolls up like a piece of paper will not be in the far distant future. Flexible organic light-emitting diodes (OLEDs), built upon a plastic substrate, have received greater attention lately for their use in next-generation displays that can be bent or rolled while still operating. |
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| A Korean research team led by Professor Seunghyup Yoo from the School of Electrical Engineering, KAIST and Professor Tae-Woo Lee from the Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH) has developed highly flexible OLEDs with excellent efficiency by using graphene as a transparent electrode (TE) which is placed in between titanium dioxide (TiO2) and conducting polymer layers. The research results were published online on June 2, 2016 in Nature Communications („Synergetic electrode architecture for efficient graphene-based flexible organic light-emitting diodes”). | |
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| This picture shows an OLED with the composite structure of TiO2/graphene/conducting polymer electrode in operation. The OLED exhibits 40.8% of ultrahigh external quantum efficiency (EQE) and 160.3 lm/W of power efficiency. The device prepared on a plastic substrate shown in the right remains intact and operates well even after 1,000 bending cycles at a radius of curvature as small as 2.3 mm. (Image: KAIST) (click on image to enlarge) | |
| OLEDs are stacked in several ultra-thin layers on glass, foil, or plastic substrates, in which multi-layers of organic compounds are sandwiched between two electrodes (cathode and anode). When voltage is applied across the electrodes, electrons from the cathode and holes (positive charges) from the anode draw toward each other and meet in the emissive layer. OLEDs emit light as an electron recombines with a positive hole, releasing energy in the form of a photon. One of the electrodes in OLEDs is usually transparent, and depending on which electrode is transparent, OLEDs can either emit from the top or bottom. | |
| In conventional bottom-emission OLEDs, an anode is transparent in order for the emitted photons to exit the device through its substrate. Indium-tin-oxide (ITO) is commonly used as a transparent anode because of its high transparency, low sheet resistance, and well-established manufacturing process. However, ITO can potentially be expensive, and moreover, is brittle, being susceptible to bending-induced formation of cracks. | |
| Graphene, a two-dimensional thin layer of carbon atoms tightly bonded together in a hexagonal honeycomb lattice, has recently emerged as an alternative to ITO. With outstanding electrical, physical, and chemical properties, its atomic thinness leading to a high degree of flexibility and transparency makes it an ideal candidate for TEs. Nonetheless, the efficiency of graphene-based OLEDs reported to date has been, at best, about the same level of ITO-based OLEDs. | |
| As a solution, the Korean research team, which further includes Professors Sung-Yool Choi (Electrical Engineering) and Taek-Soo Kim (Mechanical Engineering) of KAIST and their students, proposed a new device architecture that can maximize the efficiency of graphene-based OLEDs. They fabricated a transparent anode in a composite structure in which a TiO2 layer with a high refractive index (high-n) and a hole-injection layer (HIL) of conducting polymers with a low refractive index (low-n) sandwich graphene electrodes. This is an optical design that induces a synergistic collaboration between the high-n and low-n layers to increase the effective reflectance of TEs. As a result, the enhancement of the optical cavity resonance is maximized. The optical cavity resonance is related to the improvement of efficiency and color gamut in OLEDs. At the same time, the loss from surface plasmon polariton (SPP), a major cause for weak photon emissions in OLEDs, is also reduced due to the presence of the low-n conducting polymers. | |
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| This picture shows the new architecture to develop highly flexible OLEDs with excellent efficiency by using graphene as a transparent electrode (TE). (Image: KAIST) (click on image to enlarge) | |
| Under this approach, graphene-based OLEDs exhibit 40.8% of ultrahigh external quantum efficiency (EQE) and 160.3 lm/W of power efficiency, which is unprecedented in those using graphene as a TE. Furthermore, these devices remain intact and operate well even after 1,000 bending cycles at a radius of curvature as small as 2.3 mm. This is a remarkable result for OLEDs containing oxide layers such as TiO2 because oxides are typically brittle and prone to bending-induced fractures even at a relatively low strain. The research team discovered that TiO2 has a crack-deflection toughening mechanism that tends to prevent bending-induced cracks from being formed easily. | |
| Professor Yoo said, „What’s unique and advanced about this technology, compared with previous graphene-based OLEDs, is the synergistic collaboration of high- and low-index layers that enables optical management of both resonance effect and SPP loss, leading to significant enhancement in efficiency, all with little compromise in flexibility.” He added, „Our work was the achievement of collaborative research, transcending the boundaries of different fields, through which we have often found meaningful breakthroughs.” | |
| Professor Lee said, „We expect that our technology will pave the way to develop an OLED light source for highly flexible and wearable displays, or flexible sensors that can be attached to the human body for health monitoring, for instance.” |
| Source: The Korea Advanced Institute of Science and Technology (KAIST) |
Read more: Graphene-based transparent electrodes for highly efficient flexible OLEDS
Programul DARPA urmărește să ajute sistemele de aeronave fără pilot ale armatei americane să efectueze angajări dinamice, pe distanțe lungi, ale unor ținte solide și maritime cu mobilitate ridicată în spațiul aerian respins sau contestat, reducând în același timp lărgimea de bandă de comunicație necesară și povara cognitivă asupra supraveghetorilor umani
Cască de luptă modulară cu sistem de montare pe șină scheletată
au dezvoltat o tehnică care ar putea fi folosită pentru a face ecrane mai strălucitoare pe computer;spune că materialele realizate din aceste giroscoape artificiale trebuie să răspundă la lumină la viteze altrafast, făcându-le ideale pentru comutatoarele de mare viteză
sistemul de revizie SnowHawk Weather Goggle Revision a fost dezvoltat cu ajutorul Anon Optics, care a furnizat ochelarii de protecție a sistemului;Sistemul de revizuire SnowHawk Weather Goggle System, conceput și dezvoltat special pentru operațiunile de război arctic, este în esență o balustradă foarte confortabilă care încorporează tehnologia Anon’s Magnetic Facemask Integration pentru a „integra perfect ochelarii și balaclava, asigurând stabilizarea și etanșarea fără expunerea pielii” realizând o acoperire totală a capului și a feței, ușurința utilizării, îndepărtarea rapidă și confortul.
Doar in timp pentru vara, Samsung lanseaza un nou tracker de fitness care are ca scop subcotarea gadget-urilor de la liderul de piata Fitbit
Aplicatii in energie, combustibililor, bateriilor, purificarea apei, desalinizarea si extragerea metalelor din ea si pentru procesarea hranei
