Category Archives: STEM

Science, Technology, Engineering, and Mathematics

The future of nuclear power

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Nothing like this happened with nuclear power. It was a technology whose development was dictated by a few prominent government and military officials and large organizations and straitjacketed within narrow constraints. Most of the developers of nuclear technologies were staid, elderly bureaucrats rather than young iconoclasts like Frederic de Hoffmann. An early design invented by Admiral Hyman Rickover – suitable for submarines but hardly optimal for efficient land-based power stations – was frozen and applied to hundreds of reactors around the country. Since then there have been only a hundred or so reactor designs and only half a dozen or so prominent ones. Due to a complicated mix of factors including public paranoia, lack of economies of scale, political correctness and misunderstandings about radiation, nuclear technology was never given a chance to be played around with, to be entrusted to youthful entrepreneurs experimenting with ideas, to find its own way through the creative and destructive process of Darwinian evolution to a plateau of technological and economic efficiency. The result was that the field remained both scientifically narrow and expensive. Even today there are only a handful of companies building and operating most of the world’s reactors.

via The future of nuclear power: Let a thousand flowers bloom – Nobel Week Dialogue.

Bullet Time Effect – Frozen Raspberry Pi

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I’d been working on a PiFace interface so I could use my Raspberry Pi without a keyboard and monitor. For a bit of fun I wondered if I could turn it into a simple digital camera, that would take a picture when a button was pressed, and to my pleasant surprise, discovered you could. An idea was beginning to form in my head. If I wrote a bit more code, instead of pressing a button to take a picture, I could trigger it remotely over a network. Furthermore, it cost a lot less than any other digital camera. Could the Raspberry Pi really recreate a bullet time style effect?

via Bullet Time Effect – Frozen Raspberry Pi | PiFace.

To everyone’s amazement, including mine, it actually worked! Raspberry Pi had frozen time, recreating a Hollywood effect for a fraction of the cost. You can see the results in the video above http://youtu.be/IqoA4HeBCQ4?t=2m19s

Stealth camera takes pictures virtually in the dark

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In the team’s setup, low-intensity pulses of visible laser light scan an object of interest. The laser fires a pulse at a given location until a single reflected photon is recorded by a detector; each illuminated location corresponds to a pixel in the final image.

Variations in the time it takes for photons from the laser pulses to be reflected back from the object provides depth information about the body — a standard way of revealing three-dimensional structure. However, the algorithm developed by Kirmani and his colleagues provides that information using one-hundredth the number of photons required by existing light detection and ranging (LIDAR) techniques, which are commonly used in remote mapping or measuring forest biomass, for instance.

via Stealth camera takes pictures virtually in the dark : Nature News & Comment.

Why next man on Moon will be Chinese

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A Chinese Long March rocket is scheduled to blast off to the Moon on Sunday evening at about 6pm British time carrying a small robotic rover that will touch down on to the lunar surface in about two weeks’ time – the first soft landing on the Earth’s only natural satellite since 1976.

The take-off from the Xichang Satellite Launch Centre in Sichuan Province marks the latest stage in China’s grand ambitions not just to put a man on Moon by the end of the next decade, but to build a permanent lunar base from which it can plan missions to Mars and beyond.

via In the footsteps of the US: Why next man on Moon will be Chinese – Science – News – The Independent.

Startup Cuts Lithium-Ion Battery Costs

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So far, SolidEnergy has made small, hand-built battery cells, similar to what you would find in a cell phone, using equipment and experts at an A123 Systems lab near Boston. (A123 Systems went bankrupt last year, and was acquired by the Chinese company Wanxiang.) These experimental cells store 30 percent more energy than conventional lithium-ion batteries, but the company calculates that the approach could eventually lead to a 40 percent improvement.

via Startup Cuts Lithium-Ion Battery Costs | MIT Technology Review.

Double Robotics – Telepresence Robot for Telecommuters

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Double is the ultimate tool for telecommuting. From anywhere in the world, you have a physical presence in the office and can speak to co-workers at anytime. Double is a remotely controlled, mobile teleconferencing system, enabling conversations to happen anywhere and anytime.

via Double Robotics – Telepresence Robot for Telecommuters.

These do seem a little creepy. They appear built on Segway tech and priced at $2500. There could be some use for these such as being able to walk around a museum as shown in the video below. How much would someone pay to do walk around on your own at the Louvre in Paris without having to fly there? Perhaps one day these robots become ubiquitous to a point where entire meeting rooms consist of nothing but these robots talking with other robots.

Double by Double Robotics – Buy Now from Double Robotics on Vimeo.

Decoding radio-controlled bus stop displays

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I had the opportunity to observe a display stuck in the middle of its bootup sequence, displaying a version string. This revealed that the system is called IBus and it’s made by the Swedish company Axentia. Sure enough, their website talks about DARC and how it requires no return channel, making it possible to use battery-powered displays in remote areas.

Not much else is said about the system, though; there are no specs for the proprietary protocol. So I implemented the five-layer DARC protocol stack in Perl and was left with a stream of fully error-corrected packets on top of Layer 5, separated into hundreds of subchannels. Some of these contained human-readable strings with names of terminal stations. They seemed like an easy starting point for reverse engineering.

via absorptions: Decoding radio-controlled bus stop displays.

What does current look like on a quantum level?

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To understand how current flows in a material you first have to understand electrons behave in a material. The key feature of solid state physics is that many materials are crystals. This means that the atoms are spaced periodically. As you mention, band structures are the way that we summarize the effect of this periodic potential. Basically, a band structure just relates an electrons momentum p=mv=hbar k to its energy. The momentum can be positive or negative, the sign only denotes direction. In free space this is very boring, Energy=m v2 /2 = p2 /2m=hbar k2 /2m. When you throw in a periodic potential, this becomes modified and results in bands. Actually calculating band structures is quite difficult. The key idea is that there are ranges of energy where the electron can live and ranges of energy where the electron cannot live.

via What does current look like on a quantum level? : askscience.

Artificial Photosynthesis Made Practical

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If you want hydrogen to power an engine or a fuel cell, it’s far cheaper to get it from natural gas than to make it by splitting water. Solar power, however, could compete with natural gas as a way to make hydrogen if the solar process were somewhere between 15 and 25 percent efficient, says the U.S. Department of Energy. While that’s more than twice as efficient as current approaches, researchers at Stanford University have recently developed materials that could make it possible to hit that goal. The work is described in the journal Science.

via Artificial Photosynthesis Made Practical | MIT Technology Review.