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Our friends over at Howstuffworks have an interesting summary:

A halogen lamp also uses a tungsten filament, but it is encased inside a much smaller quartz envelope. Because the envelope is so close to the filament, it would melt if it were made from glass. The gas inside the envelope is also different -- it consists of a gas from the halogen group. These gases have a very interesting property: They combine with tungsten vapor! If the temperature is high enough, the halogen gas will combine with tungsten atoms as they evaporate and redeposit them on the filament. This recycling process lets the filament last a lot longer. In addition, it is now possible to run the filament hotter, meaning you get more light per unit of energy. You still get a lot of heat, though; and because the quartz envelope is so close to the filament, it is EXTREMELY hot compared to a normal light bulb.

Personally I'd rather use florescents. They use less energy then either solution and don't run hot to the touch. Of course I suppose they aren't ideal for all applications and if you get cheap ballasts in your fixtures they are a royal pain in the ass because the blubs keep blowing and you have no idea why.

Back in my drunk and stupid college days we used to melt floppy disks with halogen lights. Never saw one ingite sheets but it doesn't seem like a leap of faith to assume that if it can melt plastic it would ingite fabric. If I was anymore of a geek I'd look up the temperatures involved but I think I've used up my geek quota for the day :)

Our friends over at Howstuffworks have an interesting summary:

A halogen lamp also uses a tungsten filament, but it is encased inside a much smaller quartz envelope. Because the envelope is so close to the filament, it would melt if it were made from glass. The gas inside the envelope is also different -- it consists of a gas from the halogen group. These gases have a very interesting property: They combine with tungsten vapor! If the temperature is high enough, the halogen gas will combine with tungsten atoms as they evaporate and redeposit them on the filament. This recycling process lets the filament last a lot longer. In addition, it is now possible to run the filament hotter, meaning you get more light per unit of energy. You still get a lot of heat, though; and because the quartz envelope is so close to the filament, it is EXTREMELY hot compared to a normal light bulb.

Personally I'd rather use florescents. They use less energy then either solution and don't run hot to the touch. Of course I suppose they aren't ideal for all applications and if you get cheap ballasts in your fixtures they are a royal pain in the ass because the blubs keep blowing and you have no idea why.

Back in my drunk and stupid college days we used to melt floppy disks with halogen lights. Never saw one ingite sheets but it doesn't seem like a leap of faith to assume that if it can melt plastic it would ingite fabric. If I was anymore of a geek I'd look up the temperatures involved but I think I've used up my geek quota for the day :)

Even How Stuff Works is getting in on the fun:

How Hydro-Ordnance Works

Even How Stuff Works is getting in on the fun:

How Hydro-Ordnance Works

"Human power is renewable, but it's hardly clean. Or haven't you noticed the waste products?"

And it's expensive too. A bicycle racer on a 100 mi stage might burn 8000 to 10000 calories! Of course if you're touring on easy terrain and not racing through the Alps it'll be less than that, but even 2000 calories is a lot of Powerbars. Maybe you can plan your trip around all you can eat buffets. Even with gas at $2/gallon, I can go 100 mi on the motorcycle for 5 bucks.

Oh please. Rockets work because "every action has an equal and opposite reaction" - they don't work by pushing against the atmosphere, they work by throwing mass out the back of the rocket. Given the F=MV^2, current work is mostly about increasing the velocity of the mass output. Ion drives are a good example of this.

Nope. The fission reaction is just used to kick off the fusion reaction. Here, read this:

http://people.howstuffworks.com/nuclear-bomb9.htm

er, actually, no they don't.
http://electronics.howstuffworks.com/question601.h tm

Steven Weinberg, like so many scientists of a certain ilk, is just scared that funding for his favorite science projects will be cut. He's about the fourth one I've read recently who are ranting about how 'useless' manned space flight is. His vision is shortsighted and ignores the long term economic benefits, not to mention the incalculable social benefits. Too many pure-research oriented scientists are looking only at their own narrow interests. They're all wrong, wrong, wrong.

Wienberg's economic numbers are wrong. He ignores the data that have shown that the US economy experienced a long term return of over 20 to 1 on the manned space program of the 1960's. (I don't have a link to the data, sorry - it's been 10 years or so since I saw it.)

One might almost say that the American high tech industry was born in the manned space program. Tech invented or developed for NASA include silicone seal, originally developed to seal the windows in spacecraft; a wide variety of high tech metallurgy, ceramics and plastics; avionics, digital cameras, aeronautics, a huge acceleration in electronics, communications and integrated circuit technology, even areas such as systems management, risk assessment.

The manned space program gave a huge boost to engineering employment, thus encouraging a generation of Americans to get science and technical degrees, driving the tech revolution through the 1970's and beyond. Those people multiplied the pace of innovation with commercial applications and new tech. This literally changed America's view of itself from an industrial to a technological nation. Silicon Valley is in many ways a child of the manned space program!

Technologies like the hypersonic plane will have synergies with the Mars project, benefiting from the manned program budget and acting as an enabling technology. If the hypersonic plane succeeds, the potential savings for putting things in space may well pay for the entire Mars program. The projected reduction in launch cost, presently $22,000 per kg, will generate a huge increase in the number and variety of Near-Earth orbital projects, making a number of new scientific and commercial applications feasible at last, most of which nobody has thought of yet.

The technologies created will have a multiplier effect, just like in the 1960's and 1970's. For example, it may well create a real orbital vacation travel industry, which in turn will generate a stampede for commercial space projects, with the attendant operational cost reductions. Technologies for space travel will become more and more mature, greatly improving safety and reliability as well as cost. It will be ever cheaper and safer for humans to stay in space for longer terms.

Then there's the resources. Once you're out of Earth's gravity well, getting around is fairly cheap. Even beyond mining on the Moon or Mars, mining the asteroids could completely alter the economic equations on Earth. A single smallish nickel-iron asteroid contains more iron than has ever been mined on Earth. The rocky asteroids have other minerals - silicon, aluminum, etc. Once we Terrans have established a permanent presence in space, construction of spacecraft in space will become cheaper than on Earth. Space will become a net producer relative to Earth much sooner than we think.

Everything I've mentioned could be true within 50 years, possibly within 30 years. If the initiative goes forward, President Bush will be eventually be looked at as the "Queen Isabella" of space colonization, who had the vision to support Columbus and made Spain the largest economic power in Europe within 30 years. I'm looking forward to watching the next alignment of planets in 2036 from my hotel room orbiting at the Lunar L5 point.

OK, you're right about the asteroids not being ice. I was confused for a moment. Still, nickel-iron probably wouldn't make the investment worthwhile, you would need something a lot better. Now find that.

Just like on Earth, there will be impurities in the rock. Some of these impurities will take the form of things like platinum. According to this page, a 2 billion ton asteroid (1km diameter) would contain 7,500 tons of platinum. (http://science.howstuffworks.com/asteroid-mining1 .htm) Also, we know what asteroids are made out of without having to go visit them, so finding an appropriate one means doing a survey with a telescope, not a lot of time consuming and expensive space missions.

Endangering the Earth: Yes, if it is too big it will cause climate changes. The moon is an asteroid, you know.

No, it isn't. An asteroid is a specific category of planetary bodies which does not include the Moon. There are differences in formation, composition, and most importantly size. The Moon is so large that its self gravitation effectively turns it into a smooth sphere. All asteroids are oddly-shaped and lumpy because they don't have enough self gravitation to overcome the structural strength of their component rock. To give some perspective, the Moon has a mass of about 7.4e22kg. Ceres, the largest known asteroid, is about 8.7e20kg, or 1% of the Moon. As quoted above, a 1km asteroid, which we might actually think about moving around, would have a mass of 2e9kg, or about thirty trillion times less mass. It will not cause any noticeable tides.

However, that was not what I was referring to. I meant, the bigger its mass, the harder it is too control -- and we wouldn't want to lose control of an asteroid that is approaching Earth and that won't burn up in the stratosphere, would we? I mean, space shuttles blow up, so it is not as if we have this technology licked, do we?

Totally different issue. Celestial mechanics mean we can predict the path of the asteroid. We know how to do this without major errors. The worst accident that could happen would be for the propulsion to partially fail, and it would be trivial to design a propulsion system in which a partial or complete failure would result in the asteroid failing to make orbit, and simply flying off into space again. It's hard to make rockets that don't fail, but it's easy to design a flight path for a free body where a rocket failure does not result in an impact.

Carving up an asteroid: you make it sound easy.

Well, it's just a bunch of rock.

Dropping pieces of it in the atmosphere (that must be able to survive re-entry) at the right time so they land wherever they are supposed to land. You probably know the space shuttle needs constant adjustment when descending. What are you going to do: also add jets to those pieces? And then add an astronaut to them to adjust things? Remember, dropping the pieces in the sea won't work, because they'll sink.

The space shuttle needs constant adjustment because it's a big unpowered (in the descent phase) airplane. Capsules, such as Soyuz and Apollo, did use any kind of active control during their reentry. Targeting is not perfect, but it can be close enough. Use some enormous uninhabited stretch of land, like wherever the Russians recover their capsules, or the nuclear testing sites in the American southwest and put them down there.

Finally: I think "using space technology to move stuff through the atmosphere to solve a real big problem we are having" is relevant to both asteroid mining and nuclear waste disposal in space. Only nuclear waste disposal is much more urgent.

Nuclear waste disposal isn't urgent at all. We have a variety of decent solutions to the problem, including using the 'waste' as fuel in reactors designed for it or burying it in a bunch of rock. The waste issue is political, like so many othe

Of course not, which is why it isn't happening. The 2006 change over is to DIGITAL not HD. All HDTV signals are digital, but not all digital signals are hd.

Example: If you get DBS Satelite (Dish Network, DirecTv) you are getting a digital signal. If you have digital cable you're getting a partialy digitial signal.

The reason this is happening is because the FCC wants to get the Analog bands back. My understanding of this (which may be flawed, you network gurus can feel free to chime in on this) is that a digital broadcast requires less bandwidth now than the equivilient quality signal in analog. The result is that the digitial spectrum can be smaller for the same amount of content.

This gives the FCC more bandwidth to allocate for other uses, many of which may be found in emerging markets such as wireless networking devieces, particularly in the PAN and MAN arenas.

The receivers matter a great deal less here, because most TVs sold within the last 7 years or so allready have a digital tuner. The difference between HD and SD is huge, but if you're not a TV buff the only measureable advantage you'll have is that the bandwidth previously reserved for TV will be reallocated by the government for other purposes, some of which might benefit you.

Of course not, which is why it isn't happening. The 2006 change over is to DIGITAL not HD. All HDTV signals are digital, but not all digital signals are hd.

Example: If you get DBS Satelite (Dish Network, DirecTv) you are getting a digital signal. If you have digital cable you're getting a partialy digitial signal.

The reason this is happening is because the FCC wants to get the Analog bands back. My understanding of this (which may be flawed, you network gurus can feel free to chime in on this) is that a digital broadcast requires less bandwidth now than the equivilient quality signal in analog. The result is that the digitial spectrum can be smaller for the same amount of content.

This gives the FCC more bandwidth to allocate for other uses, many of which may be found in emerging markets such as wireless networking devieces, particularly in the PAN and MAN arenas.

The receivers matter a great deal less here, because most TVs sold within the last 7 years or so allready have a digital tuner. The difference between HD and SD is huge, but if you're not a TV buff the only measureable advantage you'll have is that the bandwidth previously reserved for TV will be reallocated by the government for other purposes, some of which might benefit you.

It would be hard; the amount of data that can be stored in a card's magnetic strip is very small. Format of magnetic strip data

Anyone still using superchargers? They are basically the same thing, but a supercharger is powered by the drivetrain, while a turbocharger is powered by exhaust gas.

...straight out of Back to the Future II. Anyone remember the mini-fusion generator that powered the Delorean? Now, if we could only get hoverboards , we'd be set...

The "Buyer's Club" in my store? The question is like asking "What are legitimate uses for magnetic stripe cards?"

Smart Card Uses

KFG

"Top 40" get paid to air songs.

Why? It's horrible for website navigation and it's pitiful for games.

Not trolling, I just don't get Flash. The only good thing about it is all the flash ads that I don't have to see or even download since I don't run flash.

If you paid attention in either of your HS Chemistry or Physics classes, you'd know that liquids (and even solids) are indeed compressible. The difference is each is successively orders of magnitude harder to compress.

The correct thing to say would have been that liquids are "near incompressible" and for the purposes of breaking, it is as earlier posters said the boiling point of the break fluid that is important.

Who decided that we should all be using mice to control our computer pointers? I believe (if tv doesnt lie) that it was AT&T or someone-or-rather in the late 60's, but why a mouse?

HowStuffWorks says Mice first broke onto the public stage with the introduction of the Apple Macintosh in 1984, but there were heaps of video game consoles out before that, I would have thought that a joystick style controller would have been a logical choice. Mouses are really odd.

Should anyone still be confused on how these devices work...

This should clear it up for you

OK... back to the basics of the microwave. Microwave ovens work by exciting the water (and some fats and sugars) in whatever you're heating, leaving all other compounds alone (try putting a piece of paper or a dry glass bowl in for as long as you want). The sparks that fly off metal objects like pop tart bags and CD's are caused by poor insulation in the microwave cavity. That's why we have the stigma of "Don't put metal in the microwave." Many modern microwaves don't suffer from this problem. But put enough metal in the microwave and you'll usually get a loverly light show from the high power electrical current arcing between the metal object(s) you put in and maybe even explode things. So, this dufus shoved 50 metal-laden $20 dollar bills into his microwave and expected nothing to happen? Jackass... but hey, I have a microwave that will safely disable those non-existent rfid tags for you...

Try AccessDTV It pipes the HDTV stream right onto the VGA stream but you can record (1GB/hour) and take screenshots. It was reviewed by How Stuff Works

More available amperage shouldn't result in more draw.

Correct.

Plugging your cellphone charger into a 15 amp circuit is the same as plugging it into a 20 amp. No matter what, it still draws the same power - less than one amp (or you have issues).

Correct.

Both points are irrelevant. Placing two batteries in parallel would cause the device to have twice as much power available to draw (The milliamp-hours would double) but since it draws it at the same rate (power draw = volts * amps) the result is twice the battery life.

That is Leik Myrabo's lightcraft concept. Except he usually prefers lasers instead.

On my car, the key has a microchip (or something, maybe just more like a magnetic tag) of some sort built into the key. This chip interacts somehow with something imbedded in the ignition, which allows the car to start. In other words, if you try to start the car with something other than my key, supposedly the car won't start because that chip or whatever is missing.

Actually, your car key doesn't contain a microchip. It's just a resistor.

Wasn't this thing supposed to come out, like, what, a year ago?

I still want my Indrema!

Your breath comes out at apporximately[sic] body temperature ~.

Riiiiight. So that means that your car won't start if you just drank a cold soda or hot coffee. Or you have a fever. Or the air is humid or dry. Or it is winter and you are in Chicago when the wind is blowing off the lake.

Rather than rely on urban legend like how sucking on pennies or eating underwear will make your breath heat up to "body temperature" and then you'll pass the test, you can get the actual scientific information behind how a breathalyser works.

On the other hand, this plus this will make any NM car drivable by even the drunkest felon.

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the wankel: one moving part

my buddy has an fd, oh i like those things

Yeah, but banknotes have counterfeiting stuff builtin, which the vending machine can check for. See this How Stuff Works article on the subject of currency detection. Its very informative.

The specific attributes of banknotes are only a few... while if you have some random bits of fish in the part of the grid you are analysing, there are only vague outlines to work with.

Granted, the camera will know how far away it is from the fish, so it can determine size and so on, but other features will be less easy to determine.

And how does it work with fish which have, for instance, their tail in one grid, and the rest of their body in another grid? Or are the fish physically divided into grids?

I first read about this in Newsweek a few years ago. Tim Leary and Star Trek creator Gene Roddenberry (I assume that's redundant here) already blasted off, as have a handful of others, including Princeton University physicist Gerard O'Neill, and SEDS and ISU co-founder Todd Hawley. The article describes a 2001 mission:

"For the Encounter 2001 mission, Celestis will place cremated remains into personalized flight capsules that can hold approximately one-quarter ounce (7 grams) of ashes. They will then load these capsules into a canister attached to the upper stage engine. The Encounter 2001 will initially travel into Earth's geosynchronous transfer orbit, an orbit primarily used by communications satellites. When the craft reaches the optimal point in its orbit, ground control will send a command to fire the spacecraft's solid-fuel rocket motor, propelling the spacecraft towards Jupiter. About two years later, the tiny spaceship will fly by Jupiter, using the planet's gravity to propel itself outside the solar system."

Given that a typical funeral costs around $7,000, the price doesn't seem too steep. Save a little more, skip the visitation, and get yourself a rocket.

-Oobob

The activiation temperature of battery testers is a pleasantly toasty 100-120 F.

Augmented Reality is basically annotating meatspace with metadata. This device can collect images and text and associate them with a temporal and postional location, all in realtime since the device has networking. Now if that isn't made for augmented reality data collection, I don't know what is. Now all we need is a good open, public data store like the web, a means of looking up information based on positional criteria, and come up with some decent equipment to strap to our heads... and then we've got something!

Google for 'kh-12' and 'hubble' together, or 'kh-11' and 'hubble'.

http://science.howstuffworks.com/question529.htm

http://www.astronautix.com/craft/kh11.htm

http://www.globalsecurity.org/space/systems/kh-1 2. htm

http://www.janes.com/aerospace/military/news/jsd/j sd011017_1_n.shtml

Actually, that's depressing. We have several Hubble-type satellites up there that our government just flings up there whenever the hell it wants and it won't save the one that people actually care about!? Argh. As if I weren't furious enough...

Ok, you are correct in that there isn't an energy crisis in the thermodynamic sense. However, there is a scarcity (not a crisis) of work in the thermodynamic sense.

The captured solar energy of a 150 mile by 150 mile square area of Nevada desert would provide the United States with all its energy needs: consumer, residential, transportation, commercial and industrial; oil, gas, coal, electric, etc. combined. Yes. It's a fact.

For others, I calculate that to be roughly 58 billion square meters. At roughly a KwH per meter of sunlight, you get a maximum solar input of 58 terawatts. But perhaps 30% of that can be converted (using really good solar panels) to electricity. That still should in the neighborhood of what the US consumes.

I believe others have indicated this, but even if we build this enormous structure, we have two problems. First, we need to transport the power to where it is needed. This isn't a solved problem, but we can assume that the surface area of the panels is distributed over the US rather than being concentrated in Nevada. Locating all power production in Nevada would result in vast power losses to the East coast. I'm not sure how much the 500 kilovolt lines (think they are best copper-based lines) lose, but it's probably more than 75% loss (wild guess) over thousands of kilometers.

Even if that is fixed, you have the problem of storage. This is a far more difficult problem. A large scale cost effective system that could return 50% of the power it consumed would be a vast step up for most regions of the world. Pumped water storage (pump water up into a reservior and drain it to produce electricity) seems to work where it can be placed.

"If you really want that functionality, just plug in a monitor using a second cheapo vidcard. Much more expandable..."

I really doubt anybody is buying this because it is "functionnal"

Try this

http://computer.howstuffworks.com/cable-modem.htm/ printable. Tons is defined by the cable company. Kludges are built into the DOCSIS standard. Rate limiting is no longer only handled at the cable modem itself.

If your cable modem experiences slowdowns at peak hours, blame the company, not the product.

I'd like to send him a "personal lubricant" laced with urushiol and Dimethyl Sulfoxide.

They should send up an automated Rover Wash next time; every once in a while Spirit could drive in for a full wash'n'wax (and maybe check the tyres) ...

The correct spelling is Cassegrain (after the French sculptor Sieur Guillaume Cassegrain), not Cassagrain. There are two major subtypes: Maksutov-Cassegrain or Schmidt-Cassegrain). Reference.

Of course you could say that about the internet in general, but there's something fascinatingly concise about wikipedia. The collective seems to be a lot better at modifying and adding info, then trimming out the superfluous stuff so that the language gets more concise. It seems to do a much better job than other websites where info is provided by a closed group of people, like, say, www.howstufworks.com. the latter is a great site and has some great quality graphical explanations, but wikipedia has the edge in terms of sheer breadth.

How do you think a diesel engine works? It mixes fuel and air, then compresses it to the point where it explodes... See for yourself here... Now, diesel fuel won't ignite with a match, etc, but that's a different issue.

There are serious doubts as to whether polygraph machines actually work or are simply junk science... and that criticism is of using polygraphs in a controlled environment like an interrogation room used by law-enforcement types. Now this company wants us to believe that an under-paid & under-trained security screener working in a chaotic environment like a busy airport is going to be able to detect a lie using their unproven product? Ha!

I'm sorry, because I do agree with you, but I just can't resist.

Oh, and the odds of the RTG not surviving are about the same as the black box in an airplane not surviving.

Did you know that there are several black boxes on any given airplane for different systems, and often they aren't recovered?

Ok, I'm confused. Since when do two false's make a positive. Ohh..they must be XORing the system. That makes perfect sense.

I don't follow you. For an XOR I get this truth table:

A XOR B = Q
0 XOR 0 = 0
0 XOR 1 = 1
1 XOR 0 = 1
1 XOR 1 = 0

Did you mean that SCOX NAND'ing or perhaps NOR'ing? Using NAND logic would mean that any wrong would make a right, while using NOR logic would mean that only two wrongs would make a right; other combinations of wrongs and rights would just be plain wrong. ;-)

An earth skyhook would be an engineering marvel. The job of building the 36,000 kilometer section down to the earth would be equivalent to building a suspension bridge around the equator. In order to lift appreciable loads, say 100 tons at a time, the skyhook would have to weigh 600 thousand tons. Fortunately, the carbon needed for the graphite fibers can be found in special kinds of asteroids called carbonaceous chondrites. After the carbon was extracted from the asteroid, the remaining slag could be used as the counterweight.

For comparison, the International Space Station, which is the largest structure ever built in space thus far, masses around 112 tons. The Shuttle orbiter masses around 100 tons.

So building the space elevator can be estimated as being roughly 6,000 times as hard as building ISS, or as being like launching 6,000 shuttles on one-way trips (and this neglects the fact that you need to go to geosync orbit rather than LEO, and also that you need to grab an asteroid for the counterweight, and that you need to do on-orbit fabrication of a material barely out of the laboratory right now).

FYI:

Fusion bomb

Fusion Sun

FYI:

Fusion bomb

Fusion Sun

In the '60s, GE had a project called "Hardiman". It was scrapped when they couldn't get the limbs to coordinate properly. It was also impractically heavy, at 1,500 pounds.

Currently, DARPA has a $50 million project dedicated to developing exoskeletons for US soldiers.

How Stuff Works has an article detailing some of the problems with developing exoskeletons with a few interesting links.

~~LF

It may just be a symptom of my generation, but I really think the reason we need a moon base is obvious.

I take it as a given that we need to establish a self-sufficient human presence off of this planet; we are screwing this one up at a amazing rate, and so many things exist that can destroy the race in a relatively short period of time it's ridiculous; from Planet killer asteroids, to mutant Ebola, to a new cold war, to killing all the plankton which produce the majority of our oxygen... etc.

In order to have a self -sufficient human presence in space, raw materials are going to be necessary; it's stupid to boost all the construction materials out of the earth's gravity well, when we can just mine the moon; alternately, I could see towing a asteroid to a LaGrange point, but that's possibly beyond us currently.

Once we have the moon, we have it all; a electromagnetic catapult to put processed raw materials back into orbit or shoot them to the earth would easily pay off the cost of putting a base there. The only problem I can see would be water, if ice turns out to not exist at the poles as some think (I don't); the easy availability of selenium, and abundant Solar power, should make making our own water out of elemental H & O a snap.

And, the best argument; President-for-life Bush will be able to drop gigantic canisters of rock anywhere on the planet he wants to suppress dissidents terrorists! peace in our time!.

Which is why I'm encouraging my kids to either pursue mechanical engineering or aerospace tech; I want them OFF this planet as soon as its possible.