TPT March 2020

G LOBA L MARKE T P L AC E

breaks the relationship between temperature and thermal radiation in a very particular way. Essentially, there is a temperature range within which the power of the thermal radiation emitted by our coating stays the same.” That temperature range is currently limited to between 105° and 135° Celsius; at these temperatures, the level of thermal radiation the coating emits is the same because the coating’s emissivity – the degree to which it emits light at a given temperature – actually goes down with temperature and cancels out the intrinsic radiation. Despite the restricted temperature range the research team believes further development could lead to practical applications. “We can imagine a future where infrared imaging is much more common, negatively impacting personal privacy,” said Alireza Shahsafi, a doctoral student in Kats’ laboratory and a lead author of the study. “If we could cover the outside of clothing, or even a vehicle, with a coating of this type, an infrared camera would have a harder time distinguishing what is underneath. View it as an infrared privacy shield. The effect relies on changes in the optical properties of our coating due to a change in temperature. Thus, the thermal radiation of the surface is dramatically changed and can confuse an infrared camera.” Aerospace With single-aisle aircraft in demand the C919 jet completed its first test flight The sixth prototype of China’s C919 narrow-body (single-aisle) passenger plane reached a milestone in its development in December, with the completion of its first test flight. The sixth prototype is the last test plane that the manufacturer, Commercial Aircraft Corp of China Ltd (COMAC) has planned for the program. The flight from Shanghai lasted two hours and five minutes, COMAC said in a press release, adding that the jet will be taking future test flights with a focus on cabin, lighting and external noise. The state manufacturer has already begun production of aircraft parts for its first batch of aircraft deliveries, and is aiming to obtain Chinese certification for the C919 in 2021. Designed to compete directly with the Airbus 320 and Boeing 737 in the 150-seat sector, the C919 will spearhead China’s efforts to break into the market. Airbus A320neo suits the budget Spirit Airlines, a budget airline in the US, has placed an order for 100 Airbus A320neo (new engine option) jets with an option on up to 50 further aircraft. Airbus will supply a mix of A319, A320 and A321 models to the exclusively Airbus airline. Spirit has remained faithful to the European manufacturer despite Washington’s imposition of ten per cent tariffs on some Airbus planes. Aircraft are typically ordered several years in advance, meaning any planes ordered now will only be subject to tariffs in place at the time of supply. The deal could be worth between $11bn and $12bn, depending on the final breakdown of models supplied.

The method could have the potential to be used for other natural hazards such as earthquakes, hurricanes and flooding, using existing fibre optic cable networks in urban areas throughout the US and beyond. “This research is an example of taking an existing technology and using it to serve another purpose,” Mr Stensrud said. High fibre optic cables A team of scientists from Finland’s VTT Technical Research Centre of Finland Ltd have successfully transmitted light over a new, wood-based optic fibre cable. The biodegradable cable has a cellulose core. While a wood-based network will never have the capacity for a high performance, long-lasting broadband ISP network, the research team believes the technology could be useful in sensitive environments, or used to help detect changes in the moisture levels of buildings. The core of the new optical fibre is cellulose, modified for the purpose using ionic solvents developed by VTT. “Around the core we made a cladding out of cellulose acetate. The [research] is still in its initial phases, so we do not yet know all the applications the new optical fibre could lend itself to,” said BTT’s senior scientist Hannes Orelma. As yet, testing has been restricted to fibres only a few centimetres long. VTT explained that cellulose has properties that suit it for use in optical fibre sensors: light is able to travel in the fibre because the core is surrounded by cladding material with a lower index of refraction (meaning that light is reflected back into the core from the interface of the core and the cladding). The material can, in itself, react with the substances being measured and absorb them, which is “difficult” for glass or plastic fibres. “Cellulose is also easy to modify as regards, for instance, the index of refraction. Cellulose effectively absorbs and releases water, which can be measured by the change in the attenuation of light transmitted in the fibre. In addition, cellulose is biodegradable and the fibre used for the sensor can be disposed of with biowaste,” wrote the team. Is a cloak of invisibility in sight? According to research published in the Proceedings of the National Academy of Sciences , a team in the US – consisting of engineers from UW-Madison, with contributions from Purdue and Harvard universities, Massachusetts Institute of Technology and Brookhaven National Laboratory – has developed a coating that is capable of cloaking thermal radiation at certain temperatures, and which could prevent detection by thermal cameras. The ultra-thin coating is made from samarium nickel oxide, a material with unique properties at certain temperature ranges. Objects generally grow brighter as their temperature increases, which is why infrared or thermal cameras can detect people and vehicles from the heat they emit. The new coating does not show this regular, linear relationship with heat and light, and has the potential to camouflage devices or even clothing. “This is the first time temperature and thermal light emission have been decoupled in a solid object,” said Mikhail Kats, professor of electrical and computer engineering at the University of Wisconsin-Madison. “We built a coating that

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MARCH 2020