You're a bit off on your calculations. A 2km2 swath of 3m deep would be 6x10^6m3, and will power a 1GW reactor for one year. Mining the whole volume of the moon would be 2.2x10^10km^3, or 2.2x10^19m3, which at the current installed capacity of some 2750GW, would run us for about 1.3 billion years.
You made another mistake assuming the entire moon could be mined. The regolith only extends down to about 5m in most areas, and around 15m at its deepest. That means your total volume would be considerably less at around 2.3x10^17m3, or closer to 13 million years.
Now before you go off thinking strip mining the moon is a grand idea, look at the scale of what you intend to do. That single power plant will require some 5 million metric tons of material be processed each year. That's up to almost 14 billion tons to switch our power generation capacity over to it completely, and probably double that if you want to convert our fossil fuel usage as well. In comparison, the total world production of coal is somewhere around 7 billion tons per year, with the vast majority of that easily accessed through surface veins and strip mining. You're talking about mining on an absolutely absurd scale. I'm not going to say its a bad idea, but it's certainly something that will require an enormous expenditure in machinery before it becomes viable.
Who cares? All you're concerned about is removing the video card as a factor in the benchmark. It gives you a baseline from which to compare one processor to another, even if the absolute performance values themselves are otherwise meaningless. That's the entire concept of a synthetic benchmark.
While I have no issue with people posting links to whatever they feel like, I think people should post the link directly to what they want. In a medium where character limit is not an issue and HTML tags can be used to clean up links, there are only two reasons to use URL shorteners. Either the user is an ignorant twitter or SMS user otherwise thinking such things are necessary, or they are maliciously trying to hide the destination of the link. In either scenario, I don't see a problem with rejecting a post through the submission system, with a comment to the user to use the direct link.
Is there any chance we could get bit.ly and other URL shorteners outright banned from slashdot? Since we're not constrained in character count, their only purpose is to mask the destination of links, which is a bad thing.
A modern, power efficient PC (standard higher end dual core i5) will idle at under 30watts. The standard desktop Atom systems are going to run 15-20W idle. Better options would be something ARM based like the dual-port GuruPlug Plus, or Geode based like the ALIX and Soekris boxes. I've been running an ALIX system with a 4GB CF card and 256MB of RAM as my firewall for several years now. If you have any urge to tinker, the ability to run a full mainstream OS is so much more flexible, rather than having to worry about every single KB on consumer routers that only have a few MB of memory.
That's why patents used to require a physical demonstration. Ideas were all well and good, but until you demonstrated a physical device that acted like the patent claimed, you could not get it patented. This was intended to prevent fraudulent devices that looked good on paper but could never actually be manufactured, like perpetual motion machines. It could just as easily prevent software, algorithms and business methods.
For any modern cryptographic hashing algorithm, the possibility of any two hashes colliding is astronomically low. Dropbox hashes in blocks a maximum of 4MB. That means for hundreds of terabytes of stored space, you're looking at tens to hundreds of millions of stored hashes. The number of permutations of those millions of hashes brings a hash collision into the realm of statistical possibility. It has nothing to do with vulnerabilities. Of course since those are SHA-512 hashes, with some 10**150 possibilities, it's probably not something they'll have to worry about.
I still contend that hashes should only be used to determine if two items are different, not as the sole confirmation that they are the same.
The problem is that the client only sends a hash of the file to the server to check whether the server already has that file in its global database. If this is the case, it doesn't have to be uploaded. I experienced that when I put a ~2GB file into my Dropbox, and it synced within a second (and no, I don't have a fast Internet connection). Somebody else has the same file in a Dropbox, and so the server already knows about that hash.
This seems like an intrinsically bad idea. Regardless of the hashing algorithm, there exists a possibility of a collision. Let's say you sync a file, a matching hash is found on the system, and instead of uploading your copy, they simply add that file to your account. That matching hash is not your file. You delete your local copy of the file, and that data is now lost. The only time I can think of that I could legally be uploading a duplicate file of any consequential size would be bit-accurate CD and DVD ISOs.
They can do de-duplication if they want, but it should be done server side with a direct comparison between the two files, not just a hash.
Animals will kill when the opportunity presents itself - there are no tofu eating lions out there, unless the lion takes a big bite of a vegetarians stomach.
How do you propose they create propellant from solar power? You collect energy (light) from the Sun, and transform it to matter using some as yet unknown nuclear mechanism? You can't do that with light, but you could do that with solar wind. Create a giant collection station, with a surface area of hundreds of square kilometers, and shove it at the L4/5 point. The dynamic stability at those points would ensure a space craft would maintain station on its own. With complete capture, you're looking at maybe 20ug/s/km^2. Each square kilometer would capture all of around half a kilogram of protons and electrons per year. That's simply not a consequential amount to be used as a reaction mass in any contemporary engine. You would be better off trying to gather the dust that collects at the L4 and L5 points, or even better capturing nearby asteroids.
That is not correct. Among direct, single impulse maneuvers, the Hohmann transfer is the slowest and requires the least energy. A gravitational slingshot from the moon could be used to offset some energy from the propulsion system, but is indirect. "Fuzzy orbits" operate on a similar principle, but are far more complex to compute and can take even less energy. Multiple passes of an elliptical orbit could take advantage of the Oberth effect, with multiple successive burns at the perigee of each pass. Overall, you end up using more energy than a direct Hohmann, but your engine is used more efficiently, producing more energy for less reaction mass. A long duration burn from an ion drive will consume far more energy, but will still take far longer than a Hohmann transfer.
The problem with railguns is that they are only a viable option for raw materials, fuel, and very robustly built structures. The acceleration would be too great for any complex assembly. A maglev launch could be used for more flimsy items, but you're still looking at very long launch rails, and very high accelerations for a direct insertion. For manned launches, the whole concept is completely out of the question. The best you could do would be a first stage replacement, getting the craft up to sufficient velocity that scramjet engines would function.
That said, I would be surprised if we put in the same kind of funding we did in the 60's, and couldn't have a viable launch system built in a decade that would drastically undercut anything else available.
Methane is a cryogenic liquid (or high pressure gas), meaning in the event of a crash, there would be a huge release of flammable gas and an explosion. It would effectively result in near zero survivability from nearly any aircraft crash.
Well its alright for animals to eat other animals for food, right? I mean you don't see vegans out in the forest hunting predators en' masse before they can kill and eat their prey. Somehow we have been removed from the food chain, and have to live under different rules.
Since all that heavy machinery could be run on corn ethanol, and alternative fertilizers can be used, there is no reason it would end up releasing more carbon than just using fossil fuels directly. The problem is that photosynthesis itself is less than 10% efficient, and when the planting, harvesting, and refining is all taken into account, your net output is only a couple percent of that contained in the pre-processed corn. That same plot of land plowed over with mirrors, a collection tower, and some form of heat engine, would probably produce two orders of magnitude higher useful output. Use it to split and compress hydrogen, and you still come out far far ahead.
Considering the horrendous efficiency at which corn is converted to ethanol, I can't imagine using rendered chicken fat being all that much worse. Corn ethanol itself isn't a viable renewable fuel.
This has little to do with the USAF being worried about the availability of fuel, and more about the aviation industry in general.
The ground transportation industry can move to electric fairly easily. Motor compactness, efficiency, and high torque are very advantageous for ground vehicles. The heavy weight of batteries really isn't that big of an issue. A lot of it is compensated by the smaller motors, and when regenerative braking is used, the inertia issues don't really matter. The only real issue is increased rolling friction, and at even highway speeds, aerodynamic friction is the where the majority of the power is going. Recharge time is a nuisance, but can be limited by high power, fast charge technologies.
The power industry has plenty of alternatives. Even today, only the peak load plants run hydrocarbons. With an intelligent grid and tens of millions of battery backup units (electric cars) hooked up, the peak load plants could largely be outright discarded. That leaves coal which will run out too, but in a pinch, it really wouldn't be that troublesome to switch to nuclear/solar/wind/tidal. All you need is market forces (coal costs) that make it beneficial.
When we run out of liquid hydrocarbon fuel, the aviation industry is screwed. High subsonic travel requires a ton of power. Fuel weight is a killer, and while electric motors could conceivably provide similar power density to a gas turbine, even theoretical plans for future battery technologies don't even come close to kerosene. Boranes are very toxic, and have some nasty behaviors with exhaust deposits on turbomachinery. Coal slurry has particulates which shred the high temperature components of engines. Aluminum and beryllium cannot be easily made into liquid fuels.
Gas fuels such as methane and hydrogen would burn just fine with no side effects, and have the the needed energy density, but the problem with those is storage and safety. They would take up far more volume, and that's volume in very heavy pressurized containers. When the weight of the tank is taken into account, they will still be significantly less energy dense than kerosene. Add to that the fact that storing highly flammable compressed gas in an aircraft effectively drops the crash survivability to zero.
The aviation industry will not survive as it currently does without liquid hydrocarbon fuels. Either we need to bring back the closed cycle nuclear engine, halve the speed (and quarter the drag) such that our experimental battery technology is up to the task of long distance flight, or come up with some novel as yet unknown fuel cycle. Such a fuel crisis would be a prime opportunity for high speed (300knot+) electric rail to take hold.
Jet fuels are all kerosene based specifically for the reason that at high altitudes (and low temperatures), it remains fluid. Something that is jelly at 30 below isn't going to be of much use.
Slashdot Mirror
That's what I thought. A quick search seems to indicate it's somewhat more derogatory in certain areas.
the Pakis>
Gee, mass murder not enough for you, so you gotta throw in a racial slur as well?
I had to look that one up. Is that actually a racial slur anywhere outside of Britain?
Actually, it's worse than that. The general rule of thumb is the ratio to the fourth power.
http://pavementinteractive.org/index.php?title=ESAL
You're a bit off on your calculations. A 2km2 swath of 3m deep would be 6x10^6m3, and will power a 1GW reactor for one year. Mining the whole volume of the moon would be 2.2x10^10km^3, or 2.2x10^19m3, which at the current installed capacity of some 2750GW, would run us for about 1.3 billion years.
You made another mistake assuming the entire moon could be mined. The regolith only extends down to about 5m in most areas, and around 15m at its deepest. That means your total volume would be considerably less at around 2.3x10^17m3, or closer to 13 million years.
Now before you go off thinking strip mining the moon is a grand idea, look at the scale of what you intend to do. That single power plant will require some 5 million metric tons of material be processed each year. That's up to almost 14 billion tons to switch our power generation capacity over to it completely, and probably double that if you want to convert our fossil fuel usage as well. In comparison, the total world production of coal is somewhere around 7 billion tons per year, with the vast majority of that easily accessed through surface veins and strip mining. You're talking about mining on an absolutely absurd scale. I'm not going to say its a bad idea, but it's certainly something that will require an enormous expenditure in machinery before it becomes viable.
Who cares? All you're concerned about is removing the video card as a factor in the benchmark. It gives you a baseline from which to compare one processor to another, even if the absolute performance values themselves are otherwise meaningless. That's the entire concept of a synthetic benchmark.
While I have no issue with people posting links to whatever they feel like, I think people should post the link directly to what they want. In a medium where character limit is not an issue and HTML tags can be used to clean up links, there are only two reasons to use URL shorteners. Either the user is an ignorant twitter or SMS user otherwise thinking such things are necessary, or they are maliciously trying to hide the destination of the link. In either scenario, I don't see a problem with rejecting a post through the submission system, with a comment to the user to use the direct link.
Is there any chance we could get bit.ly and other URL shorteners outright banned from slashdot? Since we're not constrained in character count, their only purpose is to mask the destination of links, which is a bad thing.
A modern, power efficient PC (standard higher end dual core i5) will idle at under 30watts. The standard desktop Atom systems are going to run 15-20W idle. Better options would be something ARM based like the dual-port GuruPlug Plus, or Geode based like the ALIX and Soekris boxes. I've been running an ALIX system with a 4GB CF card and 256MB of RAM as my firewall for several years now. If you have any urge to tinker, the ability to run a full mainstream OS is so much more flexible, rather than having to worry about every single KB on consumer routers that only have a few MB of memory.
we might even throw in an apostrophe or two for good measure.
Pretty sure that's not the English language, but just wrong.
That's why patents used to require a physical demonstration. Ideas were all well and good, but until you demonstrated a physical device that acted like the patent claimed, you could not get it patented. This was intended to prevent fraudulent devices that looked good on paper but could never actually be manufactured, like perpetual motion machines. It could just as easily prevent software, algorithms and business methods.
Ink on a digital medium that goes through CRC? Please tell me that is a joke....
For any modern cryptographic hashing algorithm, the possibility of any two hashes colliding is astronomically low. Dropbox hashes in blocks a maximum of 4MB. That means for hundreds of terabytes of stored space, you're looking at tens to hundreds of millions of stored hashes. The number of permutations of those millions of hashes brings a hash collision into the realm of statistical possibility. It has nothing to do with vulnerabilities. Of course since those are SHA-512 hashes, with some 10**150 possibilities, it's probably not something they'll have to worry about.
I still contend that hashes should only be used to determine if two items are different, not as the sole confirmation that they are the same.
The problem is that the client only sends a hash of the file to the server to check whether the server already has that file in its global database. If this is the case, it doesn't have to be uploaded. I experienced that when I put a ~2GB file into my Dropbox, and it synced within a second (and no, I don't have a fast Internet connection). Somebody else has the same file in a Dropbox, and so the server already knows about that hash.
This seems like an intrinsically bad idea. Regardless of the hashing algorithm, there exists a possibility of a collision. Let's say you sync a file, a matching hash is found on the system, and instead of uploading your copy, they simply add that file to your account. That matching hash is not your file. You delete your local copy of the file, and that data is now lost. The only time I can think of that I could legally be uploading a duplicate file of any consequential size would be bit-accurate CD and DVD ISOs.
They can do de-duplication if they want, but it should be done server side with a direct comparison between the two files, not just a hash.
Animals will kill when the opportunity presents itself - there are no tofu eating lions out there, unless the lion takes a big bite of a vegetarians stomach.
I can't tell if that was an intentional reference or not... http://www.knoble.com/family/images/Humor/tofu.gif
How do you propose they create propellant from solar power? You collect energy (light) from the Sun, and transform it to matter using some as yet unknown nuclear mechanism? You can't do that with light, but you could do that with solar wind. Create a giant collection station, with a surface area of hundreds of square kilometers, and shove it at the L4/5 point. The dynamic stability at those points would ensure a space craft would maintain station on its own. With complete capture, you're looking at maybe 20ug/s/km^2. Each square kilometer would capture all of around half a kilogram of protons and electrons per year. That's simply not a consequential amount to be used as a reaction mass in any contemporary engine. You would be better off trying to gather the dust that collects at the L4 and L5 points, or even better capturing nearby asteroids.
That's not true. The Moon is falling up.
That is not correct. Among direct, single impulse maneuvers, the Hohmann transfer is the slowest and requires the least energy. A gravitational slingshot from the moon could be used to offset some energy from the propulsion system, but is indirect. "Fuzzy orbits" operate on a similar principle, but are far more complex to compute and can take even less energy. Multiple passes of an elliptical orbit could take advantage of the Oberth effect, with multiple successive burns at the perigee of each pass. Overall, you end up using more energy than a direct Hohmann, but your engine is used more efficiently, producing more energy for less reaction mass. A long duration burn from an ion drive will consume far more energy, but will still take far longer than a Hohmann transfer.
The problem with railguns is that they are only a viable option for raw materials, fuel, and very robustly built structures. The acceleration would be too great for any complex assembly. A maglev launch could be used for more flimsy items, but you're still looking at very long launch rails, and very high accelerations for a direct insertion. For manned launches, the whole concept is completely out of the question. The best you could do would be a first stage replacement, getting the craft up to sufficient velocity that scramjet engines would function.
That said, I would be surprised if we put in the same kind of funding we did in the 60's, and couldn't have a viable launch system built in a decade that would drastically undercut anything else available.
Methane is a cryogenic liquid (or high pressure gas), meaning in the event of a crash, there would be a huge release of flammable gas and an explosion. It would effectively result in near zero survivability from nearly any aircraft crash.
Well... except for the fact that corn can only be painstakingly turned into something akin to jet fuel. There's nothing trivial or efficient about it.
Well its alright for animals to eat other animals for food, right? I mean you don't see vegans out in the forest hunting predators en' masse before they can kill and eat their prey. Somehow we have been removed from the food chain, and have to live under different rules.
Since all that heavy machinery could be run on corn ethanol, and alternative fertilizers can be used, there is no reason it would end up releasing more carbon than just using fossil fuels directly. The problem is that photosynthesis itself is less than 10% efficient, and when the planting, harvesting, and refining is all taken into account, your net output is only a couple percent of that contained in the pre-processed corn. That same plot of land plowed over with mirrors, a collection tower, and some form of heat engine, would probably produce two orders of magnitude higher useful output. Use it to split and compress hydrogen, and you still come out far far ahead.
Considering the horrendous efficiency at which corn is converted to ethanol, I can't imagine using rendered chicken fat being all that much worse. Corn ethanol itself isn't a viable renewable fuel.
The ground transportation industry can move to electric fairly easily. Motor compactness, efficiency, and high torque are very advantageous for ground vehicles. The heavy weight of batteries really isn't that big of an issue. A lot of it is compensated by the smaller motors, and when regenerative braking is used, the inertia issues don't really matter. The only real issue is increased rolling friction, and at even highway speeds, aerodynamic friction is the where the majority of the power is going. Recharge time is a nuisance, but can be limited by high power, fast charge technologies.
The power industry has plenty of alternatives. Even today, only the peak load plants run hydrocarbons. With an intelligent grid and tens of millions of battery backup units (electric cars) hooked up, the peak load plants could largely be outright discarded. That leaves coal which will run out too, but in a pinch, it really wouldn't be that troublesome to switch to nuclear/solar/wind/tidal. All you need is market forces (coal costs) that make it beneficial.
When we run out of liquid hydrocarbon fuel, the aviation industry is screwed. High subsonic travel requires a ton of power. Fuel weight is a killer, and while electric motors could conceivably provide similar power density to a gas turbine, even theoretical plans for future battery technologies don't even come close to kerosene. Boranes are very toxic, and have some nasty behaviors with exhaust deposits on turbomachinery. Coal slurry has particulates which shred the high temperature components of engines. Aluminum and beryllium cannot be easily made into liquid fuels.
Gas fuels such as methane and hydrogen would burn just fine with no side effects, and have the the needed energy density, but the problem with those is storage and safety. They would take up far more volume, and that's volume in very heavy pressurized containers. When the weight of the tank is taken into account, they will still be significantly less energy dense than kerosene. Add to that the fact that storing highly flammable compressed gas in an aircraft effectively drops the crash survivability to zero.
The aviation industry will not survive as it currently does without liquid hydrocarbon fuels. Either we need to bring back the closed cycle nuclear engine, halve the speed (and quarter the drag) such that our experimental battery technology is up to the task of long distance flight, or come up with some novel as yet unknown fuel cycle. Such a fuel crisis would be a prime opportunity for high speed (300knot+) electric rail to take hold.
Jet fuels are all kerosene based specifically for the reason that at high altitudes (and low temperatures), it remains fluid. Something that is jelly at 30 below isn't going to be of much use.