Category: Geek Stuff

Soda can furnaces

~ susie ~ 2 Comments

Awesome:

Brown, who teaches mechanical engineering at Metro State, is working with students, as well as a local nonprofit organization, Revision International, to build solar powered furnaces for homes in the neighborhood. With empty soda cans as one of the main parts of the design, the furnaces cost around $30 to make and are expected to save about the same amount in monthly energy costs.

In November, the group installed two of the heaters in homes, with more installations scheduled for later this month. And while it’s possible to “upgrade” the units — spending another $20 for an acrylic cover, $2 for a thermostat or $2.50 for a shower curtain to drape around it — that almost defeats the purpose of providing reliable and inexpensive energy, Brown said.

An initial effort, undertaken with graduate students at the University of Colorado Boulder, yielded a furnace that cost about $60. But Brown thought the price could be lowered. That was the challenge he posed to his students at Metro State, tasking them with making the units faster, cheaper and more efficient and reliable.

“You have to be really creative,” said Richard Anderson, a Metro State senior who’s part of the project team. “Right now, the unit will last for about a winter without any maintenance. If you bumped up the cost to about $100, it would last three or four times longer. But you’re talking about soda cans and computer fans that you can buy six for $10 on eBay and you’re supplying heat to an entire house.”

Anderson said the electricity used by the fans costs about two cents a day. Cool air is drawn into the unit’s base and then heated as it travels up through drilled holes in the 144 aluminum cans, which have been heated by the sun. The air then exits through ventilation holes at the top of the unit. While there has to be a supplemental source for heat at night, the units can reach about 170 degrees during the day. In one of the units installed in November, Anderson said, a room that was about 60 degrees increased to 90 degrees within 20 minutes.

“There was a little boy who was going to be sleeping there. He was going, ‘I’m going to be so warm tonight,'” Anderson said. “That was just so cool — it’s really exceeded my expectations.”

The universe is still a hologram

~ susie

spiral tribe

Except now they have proof:

A team of physicists has provided some of the clearest evidence yet that our Universe could be just one big projection.

In 1997, theoretical physicist Juan Maldacena proposed that an audacious model of the Universe in which gravity arises from infinitesimally thin, vibrating strings could be reinterpreted in terms of well-established physics. The mathematically intricate world of strings, which exist in nine dimensions of space plus one of time, would be merely a hologram: the real action would play out in a simpler, flatter cosmos where there is no gravity.

Maldacena’s idea thrilled physicists because it offered a way to put the popular but still unproven theory of strings on solid footing — and because it solved apparent inconsistencies between quantum physics and Einstein’s theory of gravity. It provided physicists with a mathematical Rosetta stone, a ‘duality’, that allowed them to translate back and forth between the two languages, and solve problems in one model that seemed intractable in the other and vice versa. But although the validity of Maldacena’s ideas has pretty much been taken for granted ever since, a rigorous proof has been elusive.

In two papers posted on the arXiv repository, Yoshifumi Hyakutake of Ibaraki University in Japan and his colleagues now provide, if not an actual proof, at least compelling evidence that Maldacena’s conjecture is true.

A non-antibiotic tool for fighting bacteria

~ susie

This is so cool:

In a study published on Tuesday in the journal Nature Communications, they described how a dragonfly led them to a nano-tech surface that physically slays bacteria.

The germ-killer is black silicon, a substance discovered accidentally in the 1990s and now viewed as a promising semiconductor material for solar panels.

Under an electron microscope, its surface is a forest of spikes just 500 nanometres (500 billionths of a metre) high that rip open the cell walls of any bacterium which comes into contact, the scientists found.

It is the first time that any water-repellent surface has been found to have this physical quality as bactericide.
Continue reading “A non-antibiotic tool for fighting bacteria” →