Drones, a technical nickname for unmanned aerial vehicles (UAVs) are gaining more and more interest and popularity. Supported by the miniaturization and cost reduction of electronic components, a new class of UAVs called Nano-air vehicles or NAVs represent the future technology for indoor and outdoor mission. One of the main considerations when building or buying a drone is the flight time and range. The flight time is nowadays a drawback for miniature unmanned aerial vehicles (UAVs). It is limited to a few minutes before requiring a forced recovery to replace exhausted batteries. Currently the batteries are the dominant technology, which possess limited operation in time and energy. The real viability to extending flight time (FT) of NAVs is possibly exploring new and more disruptive alternative solution able either to recharge a battery, or even to directly power the NAVs during the flight. A Plasmonic Nano Energy harvester is an attractive technology to extending the FT extracting the energy in mid-infrared radiation emitted from Earth's surface with Rectenna tuned to mid-infrared wavelengths (7 -14 ) m µ with a peak wavelength of about10 m µ . In this review the concepts emerging from this work identify and suggest how this novel harvester can constantly supply these flying objects for the whole day.
The design and manufacturing of different full-size mock-ups of the resonance cavity of gyrotrons, relevant for fusion applications, were performed according to two different cooling strategies. The first one relies on mini-channels, which are very promising in the direction of increasing the heat transfer in the heavily loaded cavity, but which could face an excessively large pressure drop, while the second one adopts the solution of Raschig rings, already successfully used in European operating gyrotrons. The mock-ups, manufactured with conventional techniques, were hydraulically characterized at the Thales premises, using water at room temperature. The measured pressure drop data were used to validate the corresponding numerical computational fluid dynamics (CFD) models, developed with the commercial software STAR-CCM+ (Siemens PLM Software, Plano TX, U.S.A.) and resulting in excellent agreement with the test results. When the validated models were used to compare the two optimized cooling configurations, it resulted that, for the same water flow, the mini-channel strategy gave a pressure drop was two-fold greater than that of the Raschig rings strategy, allowing a maximum flow rate of 1 × 10−3 m3/s to meet a maximum allowable pressure drop of 0.5 MPa.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.