Storing summer heat for winter
In a reverse implementation of the Tokyo pavement-watering experiments, the UK’s Transport Research Authority has buried a network of pipes which will store summer’s heat underground in insulated water pipes.
In a trial of the idea, a network of polyethylene water pipes 25 millimetres in diameter has been buried below a section of private road in the UK. The pipes are laid in rows about 15 centimetres apart and at a depth of 12 centimetres, where the ground temperature is normally about 12 °C on average. In the summer this can rise to 25 °C.
The sun warms the asphalt at the surface, which absorbs heat and in turn warms the water in the pipes. This is then pumped for storage to a second array of pipes at the side of the road, which are insulated by a 1-metre-thick layer of polystyrene.
Then in winter, when sensors detect that the temperature of the road surface has fallen to 2 °C, the warm water is pumped back to the pipes under the road where it warms the ground and prevents ice from forming on the road surface.
There is some speculation that similar methods of heating the ground might be employed to heat office blocks. Similar road systems have been built in the Netherlands and Austria, but the UK plan differs in the depth that the water is stored at. The systems in Austria and the Netherlands are buried 20 meters under the ground, which make them far more expensive to implement and maintain.
I wonder how long the water will stay warm enough to thaw the roads? The systems in the Netherlands and Austria seem like they might be more robust during an especially cold winter — being pumped back way down into their holding tanks, the Earth’s heat could warm the water again for the next time it is needed. But water stored so close to the surface has no such re-heating mechanism, and the insulation that once kept the water warm will now keep it cold.
The science of Stealth
LJ has written an article exploring the science and feasibility of the technology from the movie Stealth. Stealth, for those of you that don’t know, is about “EDI (”Eddie”) a prototype Uninhabited Combat Aerial Vehicle, or UCAV, being piloted by the US Navy.” She breaks it down:
In fact, the real-life Navy has been looking into the construction and deployment of UAVs for both combat and surveillance since the 1960s. 11 different models have been developed over the course of various programs, and 3 have entered actual production. And in the decade between 1985 and 1994, UAVs logged over 10,000 operational flight hours.
In particular, the Pioneer UAV highlights the effectiveness of such vehicles, with its great contributions to the success of Operation Desert Storm. Six of these planes flew in over 300 combat missions, their AI systems aiding in target selection, detection of enemy gunfire, and damage assessment. There was even one incident where Iraqi soldiers surrendered to a lone UAV; they knew that despite the lack of weaponry on the plane itself, they were surely being targeted by far-off battleships that had just been tipped off to their location.
LJ’s got the skinny on scramjets, space travel, and the technology that we’ve got today, and how long it might be before we see a real-world EDI. Funny, though, there doesn’t seem to be much in the way of actual stealth in Stealth. Go figure.
A battery powered by urine
I’m having flashbacks to seventh grade science class (one of my favoritest classes ever), and the voltaic pile that we made. Scientists have recently created a battery that is powered by urine, similar to the original voltaic piles, only miniaturized.
I’m not quite sure why this is so amazing given that it’s essentially technology from the 1700s. The device creates electricity via an electrochemical reaction: one side of the paper gains electrons (oxidation) and one side loses electrons (reduction). This redox reaction creates a small amount of voltage, which can be used to power small medical devices such as diabetes monitors. Urine contains glucose, the concentration of which can be used to determine the level of sugar in the blood.
The unit is much smaller than a traditional voltaic pile, but it functions on the same principle:
The battery unit is made from a layer of paper that is steeped in copper chloride (CuCl) and sandwiched between strips of magnesium and copper. This “sandwich” is then held in place by being laminated, which involves passing the battery unit between a pair of transparent plastic films through a heating roller at 120ºC. The final product has dimensions of 60 mm x 30 mm, and a thickness of just 1 mm (a little bit smaller than a credit card).
Writing in the Journal of Micromechanics and Microengineering, Lee describes how the battery was created and quantifies its performance. Using 0.2 ml of urine, they generated a voltage of around 1.5 V with a corresponding maximum power of 1.5 mW. They also found that the battery performances (such as voltage, power or duration) may be designed or adjusted by changing the geometry or materials used.
I guess the more things change, the more they stay the same?
The problem of static
Mars has been in the news quite a lot lately, especially with the success of the recent Sojourner landing and “Mars hoax“. Well, the red planet is back in the news again due to an issue that most people — unless you’re in the electronics sector — much on earth: static electricity. On Mars, though, it’s a much bigger problem for two reasons. Firstly, the potential to create an electrical charge is much greater on Mars, than it is on Earth.
When certain pairs of unlike materials, such as wool and hard shoe-sole leather, rub together, one material gives up some of its electrons to the other material. The separation of charge can create a strong electric field.
Here on Earth, the air around us and the clothes we wear usually have enough humidity to be decent electrical conductors, so any charges separated by walking or rubbing have a ready path to ground. Electrons bleed off into the ground instead of accumulating on your body.
NASA will have to overcome this obstacle in order to establish Mars and lunar bases. But the problem isn’t as simple as it might seem at first glance. Here on Earth, the moisture in the air and the ground makes absorbing the excess electrons that build up quite easy. But on Mars (and the moon), there is almost no moisture. An astronaut touching, for instance, the door to a lunar or Mars base could fry the sensitive electrical circuitry in his suit. Apollo astronauts didn’t have this problem, probably because they were not active enough to create the static charges necessarily to create an electrical shock. But astronauts on Mars, using heavy equipment, might.
On Earth, the best ground is, well, the ground. But on Mars, it might well be the martian atmosphere itself, with a little help:
On Mars, the best ground might be, ironically, the air. A tiny radioactive source “such as that used in smoke detectors,” could be attached to each spacesuit and to the habitat, suggests Landis. Low-energy alpha particles would fly off into the rarefied atmosphere, hitting molecules and ionizing them (removing electrons). Thus, the atmosphere right around the habitat or astronaut would become conductive, neutralizing any excess charge.
Solving the same problem on the moon, though, might be a little bit different:
Achieving a common ground on the Moon would be trickier, where there’s not even a rarefied atmosphere to help bleed off the charge. Instead, a common ground might be provided by burying a huge sheet of foil or mesh of fine wires, possibly made of aluminum (which is highly conductive and could be extracted from lunar soil), underneath the entire work area. Then all the habitat’s walls and apparatus would be electrically connected to the aluminum.
As always, more research and testing needs to be done. Regardless, frying space suits is a sure way to get oneself stranded on terra firma far away from home.
2-mile bore hits San Andreas fault
The first step of the San Andreas Fault Observatory at Depth (SAFOD) was completed this past week in Parkfield, California. Drilling 2.3 miles down, geologists have penetrated the fault zone at the self-proclaimed “earthquake capital of the world” to the site where earthquakes originate. The hole will be packed with steel and cement so the researchers can install sensors to measure the activity of the Fault.
SAFOD is scheduled to be completed in 2007, and will be the only permanent station inside an active fault zone.
The hole starts in the Pacific Plate just west of the actual fault, which is a visible and gaping scar on Earth’s surface in some locations along its 800-mile length. The hole then passes directly through the fault zone and into the North American plate on the east side of the rift. [Graphic]
Not only are geologists looking to predict the next big quake, but they hope to measure the smaller temblors, and watch the strain that leads up to the next Big One, which no one actually feels, and which scientists have only had rough measurements of in the past because only shallow, sub-surface, seismic measurements have been made.
Dr Michio Kaku on how to get a Unified Field theory published
Dr. Michio Kaku, professor of Theoretical Physics at CUNY, has written a six-step guide to getting a Unified Field Theory published. Dr. Kaku is the author of Parallel Worlds and Hyperspace, among others. From Dr. Kaku’s article:
1) Try to summarize the main idea or theme in a single paragraph. As Einstein once said, unless a theory has a simple underlying picture that the layman can understand, the theory is probably worthless. I will try to answer those proposals which are short and succinct, but I simply do not have time for proposals where the main idea is spread over many pages.
2) If you have a serious proposal for a new physical theory, submit it to a physics journal, just as Physical Review D or Nuclear Physics B. There, it will get the referee and serious attention that it deserves.
3) Remember that your theory will receive more credibility if your theory builds on top of previous theories, rather than making claims like “Einstein was wrong! ” For example, our current understanding of the quantum theory and relativity, although incomplete, still gives us a framework for which we have not seen any experimental deviation.
I’m a huge fan of Dr. Kaku. I’m in the process of reading Parallel Worlds, and I would very much like to interview him for polyscience.org. (I’ve been working on drafting the questions that I’d like to ask him on and off over the last two weeks.) I don’t hold much hope for a random person coming up with a successful “Theory of Everything,” but it is a nice gesture, even if it is just to cut down on his email workload. The fact that Dr. Kaku replies to his email is unusual enough as it is.
Earth scientists turning up the heat
Two new studies are increasing our understanding of the planet we live on and the forces that shape it…and it’s only proper for them to be from opposite ends of the world, as well.
In Massachusetts, a trio of geophysicists report in a letter to Nature that they have imaged a sharply-defined boundary between Earth’s rigid crust and the molten layer it rests upon. The nature of this “lithosphere-asthenosphere boundary” had previously been poorly understood, thought its existence has been widely accepted. The new data, obtained from recording sound waves traveling through the ground in eastern North America, shows a sharp gradient between the two layers that can most readily be explained by the presence of water or partly-molten rock at the boundary in addition to the steep increase in temperature.
And in Japan, researchers at the KamLAND subatomic particle detector are making great strides in understanding the origin of Earth’s magnetic field. They have succeeded in counting the number of antineutrinos (small particles produced during atomic decay) streaming from the planet’s core – 16.2 million per square centimeter per second, to be exact – and thus providing an exact measurement of its natural radioactivity. The nuclear decay responsible for these antineutrinos partly contributes to the vast amount of heat driving convection currents that churn Earth’s molten iron outer core and produce the magnetic field; with this measurement, we’ll now be able to determine the true extent of radioactivity’s role.
All in all, it’s been a pretty hot news week in earth science.