Large solar flares and their ionospheric D region enhancements


first_imgOn 4 November 2003, the largest solar flare ever recorded saturated the GOES satellite X-ray detectors, making an assessment of its size difficult. However, VLF radio phase advances effectively recorded the lowering of the VLF reflection height and hence the lowest edge of the Earth’s ionosphere. Previously, these phase advances were used to extrapolate the GOES 0.1–0.8 nm (“XL”) fluxes from saturation at X17 to give a peak magnitude of X45 ± 5 for this great flare. Here it is shown that a similar extrapolation, but using the other GOES X-ray band, 0.05–0.4 nm (“XS”), is also consistent with a magnitude of X45. Also reported here are VLF phase measurements from two paths near dawn: “Omega Australia” to Dunedin, New Zealand (only just all sunlit) and NPM, Hawaii, to Ny Alesund, Svalbard (only partly sunlit), which also give remarkably good extrapolations of the flare flux, suggesting that VLF paths monitoring flares do not necessarily need to be in full daylight. D region electron densities are modeled as functions of X-ray flux up to the level of the great X45 flare by using flare-induced VLF amplitudes together with the VLF phase changes. During this great flare, the “Wait” reflection height, H′, was found to have been lowered to ∼53 km or ∼17 km below the normal midday value of ∼70 km. Finally, XL/XS ratios are examined during some large flares, including the great flare. Plots of such ratios against XL can give quite good estimates of the great flare’s size (X45) but without use of VLF measurements.last_img read more

Photo of centipede-bot from SEAS wins honorable mention


first_imgA stunning photograph of a centipede-inspired robot (called a centipede millibot) developed by Harvard School of Engineering and Applied Sciences (SEAS) graduate student Katie Hoffman and faculty member Robert Wood was chosen as an Honorable Mention (tie) by Science and the National Science Foundation in the Photography category in the 2010 International Science & Engineering Visualization Challenge.Of their selection, the editors wrote:Imitating insects is all the rage in robotics right now. Graduate student Katie Hoffman based this 12-legged, segmented robot on the body morphology of a centipede. The top view shows the actuators that control each leg, the reflection shows the flexible connections between the segments, and the penny gives a sense of the robot’s size. Hoffman says most robots that size mimic cockroaches, which have only six legs and much more rigid bodies. By modeling a centipede, she hopes to study how flexibility and body undulations enhance locomotion.Wood, an Associate Professor of Electrical Engineering at SEAS and a Core Member of the Wyss Institute for Biologically Inspired Engineering at Harvard, oversees one of the world’s leading labs on microrobotics. The centipede millibot is part of the lab’s efforts in advancing ambulatory microrobots.Hoffman explained that the photo was not edited in any way, but came straight from the camera. Each of the legs is etched with the words “Harvard Microrobotics Lab” in 150-micron wide text.See the centipede millibot in motion.last_img read more

Tyson Fury vs Wilder showdown for £1.45BN Stadium


first_imgTyson Fury’s trilogy fight against Deontay Wilder could be held in the brand new state-of-the-art Allegiant Stadium in Las Vegas. The final details are still to be confirmed but December 19 is the targeted date and the NFL venue has been touted as an option to play host. It can seat 65,000 and cost a staggering £1.45billion to build, though there may have to be a reduced crowd of 20,000 depending on the coronavirus pandemic. The stadium, which will be home to the Las Vegas Raiders, is a 10-level domed building on a 64-acre plot to the west of Mandalay Bay.                                               £1.45BN  state-of-the-art Allegiant Stadium in Las Vegas. There are still some areas of construction to be completed but the arena is ready to host events.Advertisement FacebookTwitterWhatsAppEmail分享 Australia, New Zealand and even Macau have all been considered as possible destinations for Fury and Wilder’s third bout. But the British heavyweight’s co-promoter Bob Arum talked up the chances of Allegiant. He said: ‘That is the date that we all want (December 19). ‘That’s the date that both sides are happy with. Whether we’ll be able to do it in the stadium with limited seating, that’s in the hands of the gods Read AlsoAnthony Joshua, Tyson Fury agree terms for two-fight deal ‘Whenever they fight, I think it’s going to be a huge type of attraction, and to do it as the first fight at Allegiant Stadium would be something really special. ‘By December 19, people will say, “Yeah, maybe by then, the worst is over and they can do it”.center_img Loading…last_img read more