Phys.org December 10, 2018 An international team of researchers (Australia, Singapore, USA – Lawrence Berkeley National Laboratory, University of Illinois at Urbana – Champaign) has demonstrated electronic switching in ultrathin sodium bismuthide (Na3Bi), a topological Dirac semimetal that can carry a charge with nearly zero loss at room temperature. They demonstrated switching by subjecting the material to a low-current electric field. They found a way to grow it extremely thin, down to a single layer arranged in a honeycomb pattern of sodium and bismuth atoms, and to control the thickness of each layer they create. Topological transistors that could have […]
Terahertz laser for sensing and imaging outperforms its predecessors
MIT News December 10, 2018 For experiments, a team of researchers in the US (MIT, Sandia National Laboratory) fabricated an array of 10 pi-coupled wire lasers which has high constant power, tight beam pattern, and broad electric frequency tuning. The laser operated with continuous frequency tuning in a span of about 10 gigahertz, and a power output of roughly 50 to 90 milliwatts, depending on how many pi-coupled laser pairs are on the array. The beam has a low beam divergence of 10 degrees, which is a measure of how much the beam strays from its focus over distances. The […]
Sun-soaking device turns water into superheated steam
MIT News December 11, 2018 Researchers at MIT have built and demonstrated a solar-driven evaporation system. Top layer of the system is a metal ceramic composite and the bottom layer was coated with a material that easily and efficiently emits infrared heat. A layer of reticulated carbon foam is sandwiched between the two layers. It retains the sun’s incoming heat and can further heat up the steam rising back up through the foam. A small outlet tube allows steam to exit. The structure absorbs solar radiation and re-radiates infrared photons, which are directly absorbed by the water within a sub-100 μm penetration […]
“Sun in a box” would store renewable energy for the grid
MIT News December 5, 2018 A team of researchers in the US (MIT, Georgia Institute of Technology, National Renewable Energy Laboratory) has outlined their concept for a new renewable energy storage system, which they call Thermal Energy Grid Storage-Multi-Junction Photovoltaics (TEGS-MPV). The new design stores heat generated by excess electricity from solar or wind power in large tanks of white-hot molten silicon, which can withstand high temperatures of over 4,000 degrees Fahrenheit and then converts the light from the glowing metal back into electricity when it’s needed. Previously they developed a pump that could withstand such blistering heat and could conceivably […]
Shape-shifting origami could help antenna systems adapt on the fly
Tech Explore December 10, 2018 Researchers at the Georgia Institute of Technology focused on Miura-Ori, which has the ability to expand and contract like an accordion, to create radio frequency filters that have adjustable dimensions, enabling the devices to change which signals they block throughout a large range of frequencies. They used a special printer that scored paper to allow a sheet to be folded in the origami pattern. An inkjet-type printer was then used to apply lines of silver ink across those perforations, forming the dipole elements that gave the object its radio frequency filtering ability. They found that […]
Novel laser technology for microchip-size chemical sensors
Science Daily December 10, 2018 Researchers in Austria produced quantum cascade lasers which generate a frequency comb in the infrared range. With the help of an electrical signal of a specific frequency the quantum cascade lasers can be controlled to emit a series of light frequencies, which are all coupled together. The system is robust and can withstand temperature fluctuations, or reflections that send some of the light back into the laser. It can be easily miniaturized. The entire measuring system can be accommodated on a chip in millimeter format. The chip could be placed on a drone to measure […]
New Foldable Drone Flies Through Narrow Holes in Rescue Missions
Science Daily December 12, 2018 Researchers in Switzerland propose a novel, simpler, yet effective morphing design for quadrotors consisting of a frame with four independently rotating arms that fold around the main frame. To guarantee stable flight at all times, they exploit an optimal control strategy that adapts on the fly to the drone morphology. Using a fully autonomous quadrotor relying solely on onboard visual-inertial sensors and compute, they demonstrated the versatility of the proposed adaptive morphology in different tasks, such as negotiation of narrow gaps, close inspection of vertical surfaces, and object grasping and transportation…read more. TECHNICAL ARTICLE
New attack could make website security captchas obsolete
Science Daily December 5, 2018 Using Generative Adversarial Network (GAN) an international team of researchers (China, UK) has created a captcha solver. A captcha synthesizer automatically generates synthetic captchas to learn a base solver, and then fine-tuning the base solver on a small set of real captchas using transfer learning. They evaluated their approach by applying it to 33 captcha schemes, including those used by popular websites. It outperformed state-of-the-art text-captcha solvers with higher accuracy. Their approach can solve a captcha within 0.05 second using a desktop GPU bypassing the advanced security features employed by most modern text captcha schemes…read […]
Method to transfer entire 2D circuits to any smooth surface
Science Daily December 6, 2018 A team of researchers in the US (Rice University, Georgia State University) transferred a complete 2D multilayer InSe photodetector device onto a stripped optical fiber. They found that the near-field sensor effectively coupled with an evanescent field and accurately detected the flow of information inside. The benefit is that these sensors can now be imbedded into such fibers where they can monitor performance without adding weight or hindering the signal flow. They used polydimethylglutarimide (PMGI) as a device fabrication platform to etch and transfer to the target. They have developed passive sensors so far but […]
High-temperature electronics? That’s hot
Science Daily December 7, 2018 Commercial electronics operate between minus 40 and 85 degrees Celsius. A team of researchers in the US (Purdue University, UC Santa Cruz, Stanford University) created a material by blending a semiconductor, which can conduct electricity, and a conventional insulating polymer. They had to find the right ratio so that they merge nicely, and one doesn’t dominate the other. This results in an organized, interpenetrating network that allows the electrical charge to flow evenly throughout while holding its shape in extreme temperatures. The performance of these new polymer blend remained stable across a wide temperature range, […]