Just google for photolysis of water and you'll obtain a few hundred citations on the subject.
The vast majority of which concern photolysis of various things in water, not photolysis of water. Most of the rest describe how chlorophyll works in plants.
The few exceptions I was able to find were useless. One was a powerpoint presentation with no specific information. One was a PDF from 1978 that I'd have to buy to read.
This is why I asked for someone to dig up a link.
C'mon guys. 40-60% efficiency for sunlight to STORED energy is the frickin' holy grail. It's half an order of magnitude better than we can do with photovoltaics. Every geek in America would want to be the first guy on their block to own such a system, and I for one would be telling the whole town about it Paul Revere style. And nobody has the time to find (or perhaps write) a good web page about it.
So where can I get a water photolysis system that yields more energy out than a $15-20k photovoltaic system? Does this exist outside of research labs and plant leaves?
Coal miners die doing their jobs. Change the world already. Post a frickin' link.
Catalytic Photolysis, however, can get 40-60% efficiency, and directly produces hydrogen from water + sun
I've never heard of this before. Searching doesn't turn up much. Can you post a few links, for both the theory of operation and for manufacturers of these systems?
Please: find for me the mathematical proof that airplanes can actually fly.
You'll need a piece of letter or A4-sized paper and a sharp new #2 pencil to complete this proof.
Take the paper, and fold it in half lengthwise, then unfold. Turn the paper upside down so that the crease is pointing up. Rotate the paper so that a short side is closest to you (perpendicular to your eyesight). Take each of the corners furthest from you and fold them back to the crease at a 45-degree angle, leaving a point at the end of the crease. Fold the previously folded area towards you. Take each of the corners furthest from you and fold them to the crease, one centimeter shy of the point. Fold the point away from you. Turn the paper upside down. Fold it in half along the original crease. Orient the paper so that the original crease is towards you. Fold towards you on an imaginary line connecting the corner on the folded side that is furthest away from you with a point approximately three centimeters away from the original crease on the unfolded side. Flip upside down and repeat. Pick up the paper and relax the last two folds to a 90-degree angle.
Throw gently.
Eat the pencil.
Oh, you wanted a mathematical proof? You should have presented a mathematical assumption.
We use the sun as a giant 400000000000000000000000000 watt radar gun to "light up" the targets.
We could use something besides the sun, but unfortunately our AWACS planes just don't have the resolving capability at that range. Unfortunately we're limited by international treaty here - google search for "inverse square law" for more on that.
For example, if we can only detect an object from 1,000 LightYears away
The Solar System is, for all practical purposes, only about one light day across. Just about any object that could cause us harm is within the heliopause.
what if that thing is moving at 1 million LY? Wouldn't we be hit seconds after we 'saw' it?
One million light years is not a speed. Granted, some people say they were "going 60 miles" when they mean "60 miles per hour", but any implied time measurement would have to be at least 1 million years. Otherwise your killer asteroid would be travelling faster than the speed of light.
Most asteroids near earth's orbit are moving in (very roughly) the same orbital speed range as earth - 15 km/sec. The more elliptical the orbit, the closer the asteroid will be to perihelion (its maximum speed) as it crosses earth's orbit, and the faster it will be moving in comparison with earth.
The problem is, in order to see something, it has to produce or reflect light, or get in the way of something else that does. We're pretty dependant on the sun to light them up, so it's especially tough to see the ones coming back from the sun towards us (it's like seeing a very tiny new moon).
Assuming your country is the continental US and you're on opposite ends, and allowing that fiber follows trains, not birds, that's still under 10000 miles total.
Light can get there and back in 53.68 milliseconds.
Given a great-circle route, light can get anywhere on earth and back (40000km) in 133.43 milliseconds. Perfectly respectable for Quake.
A lot of time is wasted at the slower links at the two endpoints. Backbone routers can usually get a packet to where it's going in a millisecond or two.
Old school PATA devices dont have this, so every time you connect/disconnect while running... you have the risk of shorting and blowing your drive/MB
Just how does a data connection making/breaking contact before a power connection cause a short? It's not like the power gets shunted to a data line or ground in such a scenario.
Actually, what often happens is that if a drive isn't connected to ground, it can transmit signals at unexpected voltage levels onto the bus. Nothing that should fry anything, but it might wedge the bus and you might have to reboot the system.
It's also possible for static electricity to discharge through a data line as you are connecting it, but if your card/board or drive can't handle that, then it deserves to die anyway.
In short, hot-swapping almost anything isn't as dangerous as you would be led to believe, but unless it's designed for it, you do risk crashing the machine. (With that said, I still don't hot-swap PCI cards unless it's specifically supported.)
Supposedly they even tried developing a system called an MHD that would push water with no moving parts
MHD is Magnetohydrodynamic. It's like a coilgun, but with water as the projectile. Let water pass through the middle of a large electromagnet, put current through it, and it will want to move.
Unfortunately the effect of this is rather weak compared to the power required, which is why the people who are working on it are using superconductors and such. Here's a good overview.
Also it requires an ionic solution such as salt water to work. Submarines are often used to stealthily swim up rivers and into freshwater ports - this may not be possible with MHD propulsion, although maybe the average river is polluted enough to allow it to work.
One transition strategy calls for most computers to simultaneously have both IPv4 and IPv6 addresses. The problem with this approach is that there's never a good time to have people start deploying systems that are only V6--that's because somewhere, somebody is going to have a machine that's V4 only, and they won't be able to communicate with you.
I think that admins will find themselves not bothering with IPv4 for individual things at their site when they find themselves out of IPv4 addresses for less-critical things.
For example, pretend it's 2008 and IPv6 is commonplace. You have a IPv4/28 from your provider. You also have an IPv6/48. The/28 has been fully allocated since 2006. Your www.yourcompany.com server will have an ordinary A record pointing IPv4 users at it for a long time yet, but what's your plan to let people on the outside get to your [insert-not-entirely-mission-critical-thingy-here] server (that happens to work with IPv6)?
It's an even easier decision if you, as a home user, get a single static IPv4 address for your DSL line as well as an IPv6/48.
I mean really, WHY ? Just because they think they can? What are the possible implication in a commercial market?
If a manned solar-powered plane can fly around the world, then one could conclude that an unmanned solar-powered plane could reliably operate for indefinate periods of time above a city or region while carrying a substantial payload.
We can create controllable aircraft that don't ever have to land. That's huge.
Such a plane could function as the equivalent of a local communications satellite, with the latency benefits of not being thousands of miles away in geosync orbit. It could transmit and receive line-of-sight microwave communications with hundreds of thousands of people. It could relay data to other planes hundreds of miles away. It would also be several orders of magnitude less expensive to fly, and would be maintainable.
Businesses are spending hundreds, sometimes thousands, of dollars a month on reliable private communications between their offices in the same city. There is definately a market for this.
I'm not an Electrical Engineer, but would this system be able to tell where I am located if I'm using something like a yagi or parabolic dish from several miles away?
A directional antenna is like a flashlight. It's pretty easy to find someone shining a flashlight at you. To answer your second question, it's no harder to find someone using multiple flashlights.
Once you know the general direction, you can drive there, and once you get close enough, there will be more than enough signal from the antenna's sidelobes to finish the triangulation.
For what it's worth, you only need triangulation to determine range. It's possible to determine the direction of a signal without pointing directional antennas around while looking at signal meters. By putting two dipoles a known distance away from each other and comparing the phase of the returned signal (like humans do with their ears) they can determine direction - with a third dipole, or by rotating the array, they can determine whether the signal is in front or behind them.
For more information on this, google search for some combination of "foxhunt", "radio direction finding", "RDF", or "TDOA".
Is Gasoline costly, vs power directly from the grid?
Keep in mind that while chemical-to-heat reactions can be made over 90% efficient, chemical-to-heat-to-motion reactions in a typical portable generator are more comparable to car engines - 30-40% efficient (non-portable large-scale multi-stage turbine generators can do more like 60-70%). If you're storing the resulting electricity in a lead-acid battery, that's only 70% efficient.
Assume that you have an average 35%-efficiency generator charging lead-acid batteries. That system has an efficiency of 24%.
Given that
gasoline stores about 130 megajoules of energy per gallon, and you can recover 31MJ of that (same as 8.61kWh), and it costs you $1.50, then the break-even point is $1.50/8.61 (or $.174) per kWh. If you're not charging batteries, then the break-even point is $.118/kWh.
For me at least, the grid is significantly cheaper. As it should be.
Also, if you need the waste heat from the generator anyway (and can rig up a way to exchange it without dying from carbon monoxide), that could make generation a lot more worthwhile.
A 13 amp extension cord is usually 16-gauge, sometimes 14-gauge for the longer ones.
19 amps running through 16-gauge wire (4.094 ohms per 1000') converts about 1.48 watts per foot to heat.
You'd have to run this extension cord through some amazingly perfect thermal insulation (carpeting won't do it) before anything could get to flashpoint.
Standard amperage limits are based off acceptable voltage drops, not heating.
The factor they always leave out is how much of a temperature rise one can tolerate at the heat sink. Let's assume that the incoming water will be no higher than 40C and the CPU can become no hotter than 60C - that's 20C rise.
1 kilowatt is 1000 joules per second, or 238 gram calories per second. Conveniently, a gram calorie is the energy needed to raise a gram of water one degree celcius. For water, one gram is also one milliliter. So, a single gram of water will be raised 238 degrees C in one second. We don't want it to be raised more than 20C, so we need to exchange water at a rate of 238/20 = 11.9 mL/sec.
Heat sinks aren't perfect - the outgoing water will always be colder than the CPU. Let's pretend that this sink is 50% efficient (the CPU rises to a temperature, relative to the incoming water, of twice that of the outgoing water). Ergo, we need 23.8 mL/sec.
Slashdot Mirror
The vast majority of which concern photolysis of various things in water, not photolysis of water. Most of the rest describe how chlorophyll works in plants.
The few exceptions I was able to find were useless. One was a powerpoint presentation with no specific information. One was a PDF from 1978 that I'd have to buy to read.
This is why I asked for someone to dig up a link.
C'mon guys. 40-60% efficiency for sunlight to STORED energy is the frickin' holy grail. It's half an order of magnitude better than we can do with photovoltaics. Every geek in America would want to be the first guy on their block to own such a system, and I for one would be telling the whole town about it Paul Revere style. And nobody has the time to find (or perhaps write) a good web page about it.
So where can I get a water photolysis system that yields more energy out than a $15-20k photovoltaic system? Does this exist outside of research labs and plant leaves?
Coal miners die doing their jobs. Change the world already. Post a frickin' link.
I've never heard of this before. Searching doesn't turn up much. Can you post a few links, for both the theory of operation and for manufacturers of these systems?
...said the parent to their infatuated child.
You'll need a piece of letter or A4-sized paper and a sharp new #2 pencil to complete this proof.
Take the paper, and fold it in half lengthwise, then unfold. Turn the paper upside down so that the crease is pointing up. Rotate the paper so that a short side is closest to you (perpendicular to your eyesight). Take each of the corners furthest from you and fold them back to the crease at a 45-degree angle, leaving a point at the end of the crease. Fold the previously folded area towards you. Take each of the corners furthest from you and fold them to the crease, one centimeter shy of the point. Fold the point away from you. Turn the paper upside down. Fold it in half along the original crease. Orient the paper so that the original crease is towards you. Fold towards you on an imaginary line connecting the corner on the folded side that is furthest away from you with a point approximately three centimeters away from the original crease on the unfolded side. Flip upside down and repeat. Pick up the paper and relax the last two folds to a 90-degree angle.
Throw gently.
Eat the pencil.
Oh, you wanted a mathematical proof? You should have presented a mathematical assumption.
We use the sun as a giant 400000000000000000000000000 watt radar gun to "light up" the targets.
We could use something besides the sun, but unfortunately our AWACS planes just don't have the resolving capability at that range. Unfortunately we're limited by international treaty here - google search for "inverse square law" for more on that.
The Solar System is, for all practical purposes, only about one light day across. Just about any object that could cause us harm is within the heliopause.
what if that thing is moving at 1 million LY? Wouldn't we be hit seconds after we 'saw' it?
One million light years is not a speed. Granted, some people say they were "going 60 miles" when they mean "60 miles per hour", but any implied time measurement would have to be at least 1 million years. Otherwise your killer asteroid would be travelling faster than the speed of light.
Most asteroids near earth's orbit are moving in (very roughly) the same orbital speed range as earth - 15 km/sec. The more elliptical the orbit, the closer the asteroid will be to perihelion (its maximum speed) as it crosses earth's orbit, and the faster it will be moving in comparison with earth.
The problem is, in order to see something, it has to produce or reflect light, or get in the way of something else that does. We're pretty dependant on the sun to light them up, so it's especially tough to see the ones coming back from the sun towards us (it's like seeing a very tiny new moon).
I predict that after a few more wars, that will be revised to something like "somewhere along the line, people have to go in and secure the ground."
Happily, that is, until you call them an asshole.
Assuming your country is the continental US and you're on opposite ends, and allowing that fiber follows trains, not birds, that's still under 10000 miles total.
Light can get there and back in 53.68 milliseconds.
Given a great-circle route, light can get anywhere on earth and back (40000km) in 133.43 milliseconds. Perfectly respectable for Quake.
A lot of time is wasted at the slower links at the two endpoints. Backbone routers can usually get a packet to where it's going in a millisecond or two.
How do foghorns work then?
Is learning a competitive contest?
Just how does a data connection making/breaking contact before a power connection cause a short? It's not like the power gets shunted to a data line or ground in such a scenario.
Actually, what often happens is that if a drive isn't connected to ground, it can transmit signals at unexpected voltage levels onto the bus. Nothing that should fry anything, but it might wedge the bus and you might have to reboot the system.
It's also possible for static electricity to discharge through a data line as you are connecting it, but if your card/board or drive can't handle that, then it deserves to die anyway.
In short, hot-swapping almost anything isn't as dangerous as you would be led to believe, but unless it's designed for it, you do risk crashing the machine. (With that said, I still don't hot-swap PCI cards unless it's specifically supported.)
MHD is Magnetohydrodynamic. It's like a coilgun, but with water as the projectile. Let water pass through the middle of a large electromagnet, put current through it, and it will want to move.
Unfortunately the effect of this is rather weak compared to the power required, which is why the people who are working on it are using superconductors and such. Here's a good overview.
Also it requires an ionic solution such as salt water to work. Submarines are often used to stealthily swim up rivers and into freshwater ports - this may not be possible with MHD propulsion, although maybe the average river is polluted enough to allow it to work.
One transition strategy calls for most computers to simultaneously have both IPv4 and IPv6 addresses. The problem with this approach is that there's never a good time to have people start deploying systems that are only V6--that's because somewhere, somebody is going to have a machine that's V4 only, and they won't be able to communicate with you.
I think that admins will find themselves not bothering with IPv4 for individual things at their site when they find themselves out of IPv4 addresses for less-critical things.
For example, pretend it's 2008 and IPv6 is commonplace. You have a IPv4 /28 from your provider. You also have an IPv6 /48. The /28 has been fully allocated since 2006. Your www.yourcompany.com server will have an ordinary A record pointing IPv4 users at it for a long time yet, but what's your plan to let people on the outside get to your [insert-not-entirely-mission-critical-thingy-here] server (that happens to work with IPv6)?
It's an even easier decision if you, as a home user, get a single static IPv4 address for your DSL line as well as an IPv6 /48.
Where is this a quote from? The article and site show an aircraft with traditional propellers on its tail.
What ESA is claiming is new about this mission
European Space Agency? Where were they mentioned?
is that they'll be combining ion propulsion with gravity assist maneuvers
Aircraft, as a rule, do not perform gravity assist maneuvers. It's a horrible faux paus.
The parent was likely cut-n-pasted from somewhere else. Moderate appropriately.
If a manned solar-powered plane can fly around the world, then one could conclude that an unmanned solar-powered plane could reliably operate for indefinate periods of time above a city or region while carrying a substantial payload.
We can create controllable aircraft that don't ever have to land. That's huge.
Such a plane could function as the equivalent of a local communications satellite, with the latency benefits of not being thousands of miles away in geosync orbit. It could transmit and receive line-of-sight microwave communications with hundreds of thousands of people. It could relay data to other planes hundreds of miles away. It would also be several orders of magnitude less expensive to fly, and would be maintainable.
Businesses are spending hundreds, sometimes thousands, of dollars a month on reliable private communications between their offices in the same city. There is definately a market for this.
A directional antenna is like a flashlight. It's pretty easy to find someone shining a flashlight at you. To answer your second question, it's no harder to find someone using multiple flashlights.
Once you know the general direction, you can drive there, and once you get close enough, there will be more than enough signal from the antenna's sidelobes to finish the triangulation.
For what it's worth, you only need triangulation to determine range. It's possible to determine the direction of a signal without pointing directional antennas around while looking at signal meters. By putting two dipoles a known distance away from each other and comparing the phase of the returned signal (like humans do with their ears) they can determine direction - with a third dipole, or by rotating the array, they can determine whether the signal is in front or behind them.
For more information on this, google search for some combination of "foxhunt", "radio direction finding", "RDF", or "TDOA".
90% chemical-to-heat efficiency
30-40% internal-combustion engine efficiency
60-70% large scale turbine efficiency
70% lead-acid battery efficiency
Another reference for gasoline energy density
Which numbers were out to lunch in the real world, and what are the correct numbers?
Keep in mind that while chemical-to-heat reactions can be made over 90% efficient, chemical-to-heat-to-motion reactions in a typical portable generator are more comparable to car engines - 30-40% efficient (non-portable large-scale multi-stage turbine generators can do more like 60-70%). If you're storing the resulting electricity in a lead-acid battery, that's only 70% efficient.
Assume that you have an average 35%-efficiency generator charging lead-acid batteries. That system has an efficiency of 24%.
Given that gasoline stores about 130 megajoules of energy per gallon, and you can recover 31MJ of that (same as 8.61kWh), and it costs you $1.50, then the break-even point is $1.50/8.61 (or $.174) per kWh. If you're not charging batteries, then the break-even point is $.118/kWh.
For me at least, the grid is significantly cheaper. As it should be.
Also, if you need the waste heat from the generator anyway (and can rig up a way to exchange it without dying from carbon monoxide), that could make generation a lot more worthwhile.
A 13 amp extension cord is usually 16-gauge, sometimes 14-gauge for the longer ones.
19 amps running through 16-gauge wire (4.094 ohms per 1000') converts about 1.48 watts per foot to heat.
You'd have to run this extension cord through some amazingly perfect thermal insulation (carpeting won't do it) before anything could get to flashpoint.
Standard amperage limits are based off acceptable voltage drops, not heating.
Maybe you wanted "motivated"?
The factor they always leave out is how much of a temperature rise one can tolerate at the heat sink. Let's assume that the incoming water will be no higher than 40C and the CPU can become no hotter than 60C - that's 20C rise.
1 kilowatt is 1000 joules per second, or 238 gram calories per second. Conveniently, a gram calorie is the energy needed to raise a gram of water one degree celcius. For water, one gram is also one milliliter. So, a single gram of water will be raised 238 degrees C in one second. We don't want it to be raised more than 20C, so we need to exchange water at a rate of 238/20 = 11.9 mL/sec.
Heat sinks aren't perfect - the outgoing water will always be colder than the CPU. Let's pretend that this sink is 50% efficient (the CPU rises to a temperature, relative to the incoming water, of twice that of the outgoing water). Ergo, we need 23.8 mL/sec.
How is this a problem?
(Just visit it. Young-Hae Chang is a frickin' genius.)
Then, those of us with a Referrer: header agenda will finally have our opportunity.
So given Shannon's Law, how can a ternary or quaternary computer be faster?