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New Materials Enable Flapping Robotic Wings

Dielectric elastomers, popular materials in robotic hands, soft robots, tunable lenses, and pneumatic valves, may now be used to create flapping robotic wings.Researchers from the Harbin Institute of Technology in Weihai, China and the University of California, Los Angeles (UCLA), have discovered a new resonance phenomenon in a dielectric elastomer rotary joint. By applying alternating voltages to the electro-active polymer, the joint continuously bends at different angles. When the rotational inertia of the joint or the applied voltage is large enough, the joint deforms beyond 90 degrees to 180 degrees.The new phenomenon makes the dielectric elastomer joint a good candidate for creating a soft and lightweight flapping wing for robotic birds. The development would be more efficient than bird wings based on electrical motors due to the higher energy conversion efficiency (60 to 90 percent) of the dielectric elastomer. Made by sandwiching a soft insulating elastomer film between two compliant electrodes, dielectric elastomers can be squeezed and expanded in a plane when a voltage is applied between electrodes. In contrast to actuators based on rigid materials such as silicon, dielectric elastomers reach a very large extent of stretch, enabling new possibilities in many fields, including soft robotics, tunable optics, and cell manipulation. SourceAlso: Read Aeronautics tech briefs.

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NASA Demonstrates Aircraft Electric Propulsion

NASA’s Leading Edge Asynchronous Propeller Technology (LEAPTech) project will test the premise that tighter propulsion-airframe integration, made possible with electric power, will deliver improved efficiency and safety, as well as environmental and economic benefits. NASA researchers will perform ground testing of a 31-foot-span, carbon composite wing section with 18 electric motors powered by lithium iron phosphate batteries. The experimental wing, called the Hybrid-Electric Integrated Systems Testbed (HEIST), is mounted on a specially modified truck. Testing on the mobile ground rig assembly will provide valuable data and risk reduction applicable to future flight research. Researchers hope to fly a piloted X-plane within the next couple years after removing the wings and engines and replacing them with an improved version of the LEAPTech wing and motors. Each motor can be operated independently at different speeds for optimized performance. Key potential benefits of LEAPTech include decreased reliance on fossil fuels, improved aircraft performance and ride quality, and aircraft noise reduction. Source:

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Second, Smaller Rotor Increases Wind Turbine Efficiency

Large wind turbine blades disturb the wind, creating a wake behind them and reducing the energy harvest of any downwind turbines. A turbine sitting in the slipstream of another can lose 8 to 40 percent of its energy production, depending on conditions. By adding a smaller, secondary rotor mounted mounted in front of the big rotor, the two sets of blades are separated by the nacelle that houses the generating machinery on top of the tower. The extra blades can increase a wind farm’s energy harvest by 18 percent. Researchers are using advanced computer simulations, including high-fidelity computational fluid dynamics analysis and large eddy simulations, to find the best aerodynamic design for a dual-rotor turbine. Where, for example, should the second rotor be located? How big should it be? What kind of airfoil should it have? Should it rotate in the same direction as the main rotor or in the opposite direction? Source:

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Researchers Turn Packing Peanuts into Battery Parts

While setting up their new lab, Purdue University researchers ended up with piles of packing peanuts. Professor Vilas Pol suggested an environmentally friendly way to reuse the waste.The team converted their lab's extra packing peanuts into high-performance carbon electrodes for rechargeable lithium-ion batteries. The batteries outperform conventional graphite electrodes. Carbon-nanoparticle and microsheet anodes were built from polystyrene and starch-based packing peanuts, respectively.Packing peanuts, though valuable for shipping, are difficult to break down and often end up in landfills. The polystyrene peanuts also contain chemicals and detergents that can contaminate soil and aquatic ecosystems.With the Purdue method, the peanuts are heated between 500 and 900 degrees Celsius in a furnace under inert atmosphere, and in the presence or absence of a transition metal salt catalyst. The resulting material is then processed into the anodes.Commercial anode particles are about 10 times thicker than the new anodes and have higher electrical resistance, which increase charging time. The Purdue method is potentially practical for large-scale manufacturing."In our case, if we are lithiating this material during the charging of a battery it has to travel only 1 micrometer distance, so you can charge and discharge a battery faster than your commercially available material," Pol said.Future work will include steps to potentially improve performance by increasing the surface area and pore size to improve the electrochemical performance.SourceAlso: Learn about an Optical Fiber for Solar Cells.

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Self-Powered Sensors Communicate Building Defects

Michigan State University researchers have developed a technology that allows sensing, communication, and diagnostic computing — all within the building material of a structure. Using energy harvested from the structure itself, the "substrate computing" system features sensors that continuously monitor and report on the building's integrity.“Adoption of such monitoring has previously been limited because of the frequency of battery replacement for battery-powered sensors,” said Subir Biswas, professor of electrical and computer engineering, “as well as the need for a separate communication subsystem usually involving radio frequency sensor networks.”In the future, the technology will be routinely used in building materials so that structures, such as bridges, will be able to detect and diagnose potential problems, without the need for an external energy source and a separate wireless sensor network. The researchers' goal is to integrate all of the functions within a 3 x 3-millimeter electronic chip, which can be embedded within the material of a structure. Source Also: Read other Sensors tech briefs.

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Quantum Radar Detects “Invisible” Objects

A prototype quantum radar has the potential to detect objects that are invisible to conventional systems. The new breed of radar is a hybrid system that uses quantum correlation between microwave and optical beams to detect objects of low reflectivity, such as cancer cells or aircraft, with a stealth capability. Because the quantum radar operates at much lower energies than conventional systems, it has the long-term potential for a range of applications in biomedicine including non-invasive NMR scans. A conventional radar antenna emits a microwave to scan a region of space. Any target object would reflect the signal to the source, but objects of low reflectivity immersed in regions with high background noise are difficult to spot using classical radar systems. In contrast, quantum radars operate more effectively and exploit quantum entanglement to enhance their sensitivity to detect small signal reflections from very noisy regions. The radar could be operated at short distances to detect the presence of defects in biological samples or human tissues in a completely non-invasive fashion, thanks to the use of a low number of quantum-correlated photons. Source:

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Sound Waves Detect Aircraft Structural Defects

A system for using sound waves to spot potentially dangerous cracks in pipes, aircraft engines, and nuclear power plants has been developed by a University of Strathclyde researcher. A study found that transmitting different types of sound waves can help to detect structural defects more easily. This is achieved by varying the duration and frequency of the waves, and using the results to recreate an image of the component's interior. The system is a model for a form of non-destructive testing that uses high-frequency mechanical waves to inspect structure parts and ensure they operate reliably, without compromising their integrity. It could potentially have applications in medical imaging and seismology. Source:

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