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Comment Re:home use? (Score 2) 270

You would have to get it up to a high enough temperature to stay molten throughout the night, while still providing power. It's a lot more practical to use other solar technologies for home use and keep these ones in big arrays. It's a bit like why power plants will always have higher efficiency than home generation, it's a matter of scale.

Comment Re:jamie and adam said "busted" (Score 2, Informative) 270

They didn't have the desert sun pouring onto a thousand large mirrors perfectly aligned on something for hours on end. Their test was more about the ability to align all of these mirrors without technology. These kind of things are dependent on energy going in vs energy going out. A thin sail surrounded by cool damp sea air only being shone upon from one side is going to have a lot less energy going in, and a lot more energy going out than a desert solar array.

Comment Re:And yet /. promotes IPv6 (Score 2) 109

Perhaps, but what choice so we have? Once we run out of v4 addresses we have to do something.
Also: IPv6 is initially allocated via geographical areas.

More importantly, it doesn't matter how sparse the table is as long as each section is contiguous. If I know I can send any traffic from (made up protocol) hosts 1 to 1000 to router 1200, and any hosts from 10,000,000 to 10,010,000 to router 4500, then my table is just fine.

As the life of an address space goes on it will tend to become less compacted, switching to a new one that is huge will make a sparse, but compacted table.

Comment Re:Now more fraud can be blamed on you. (Score 1) 239

For physical products then wouldn't that be Walmart stealing? Or at least a breach of contract. If Walmart had a contract with the manufacturer saying that the manufacturer would be paid when the item is sold, and Walmart doesn't pay... The manufacturer doesn't have any right to ask you for money. You had an implied contract when you bought the item. Walmart has an contract with the manufacturer. You have no relation to the manufacturer.

Services are a little different as it's a continual transaction. At most when Verizon doesn't pay DirectTV it would cause a breach of contract between Verizon and DirectTV. DirectTV can then turn off your service causing another breach of contract between you and Verizon. DirectTV billing you should (in a rational world) be illegal, you never had a contract with DirectTV.

DirectTV can ask, but they have no right to demand payment. I'm not saying you weren't billed by them, but if I couldn't get them to withdraw the bill I'd just ignore it. Anything beyond that is stealing.

Comment Re:Smudges on card will reveal the PIN. (Score 1) 239

Assuming you know which numbers are pressed you don't know the order.
4 digit pin = 4 factorial -> 24 permutations
5 digit pin = 5 factorial -> 120 permutations
6 digit pin = 6 factorial -> 720 permutations ...
9 digit pin = 9 factorial ->362,880 permutations

It's pointless to bother brute forcing it beyond 5 digits, since you have to manually input the digits.

Comment Re:solar power? (Score 1) 123

The oil being collected is generally very heavy, but can vary in composition. Oil of that type cannot be used in any normal type of combustion engine. That limits you to engine that rely solely on difference in temperatures rather than ones that try to control combustion. You could run a sterling engine off of this, but you have to consider what happens between oil slicks in the same area. If the slicks are too far apart, your robots run outta energy and just sit.

Solar energy on the other hand will always be there tomorrow. I don't know what conditions are required for these bots to get enough power out of their solar panels, but if it's cloudy and they can't do much you just have to wait a couple of days.

Comment Re:Hmm... (Score 1) 357

Well that critical mixture is more of a range. It doesn't have to be a perfect mixture, just close. There has to be enough combustible density for ignition energy to pass from one particle to another, and enough oxygen density so that the combustibles can cause combustion. This is close to how a fuel air bomb works. However it's likely that the explosion heard wasn't directly related to the hydrogen at all. (skip to the 4th paragraph)

Note that the combustible density has to be high for stable/weak combustibles, or it can be lower for unstable/strong combustibles. Hydrogen is rather unstable (doesn't need much activation energy) and thus the particles can be really close, or relatively spread out.

Not all of the combustible has to go at the same instant, an explosion in one part might cause the density in another part to change, or could collectively give enough energy to cause ignition. Some things not normally considered explosive can become explosive if given the proper conditions (including a pressure vessel). Sugar dust, wheat dust, flour, and sawdust have been known to cause explosions in very rare conditions.

A pressure vessel failing is essentially an explosion, so it could be that the tank failed, and it just happened to be filled with this flammable gas, which then caused a fire. An explosion in the tank is nearly impossible, simply because there is no oxygen. Most combustibles need some sort of a pressure vessel to cause a proper explosion, if the ignition velocity is not fast enough, then it will cause a big fireball (think Hollywood explosion) but won't cause much explosion damage.

The real safety problem with using compressed hydrogen as a vehicle fuel is that it is a compressed gas. Even if a tank failure doesn't cause a lot of damage, the hydrogen will come out very quickly, leading to a possible fire. This isn't a problem with gasoline as it is a liquid, and on top of that only the vapors are really flammable. I don't know the safety ratings on a hydrogen tank put in a car, but the tanks would have to be done very well to be equal in safety to a gasoline tank (which can have inner bladders, that don't work with compressed hydrogen).

Hydrogen stored in metal hydrates is very stable, and easily safer than gasoline. But I don't think the energy density is high enough yet for practical use.

This post ended up being a lot longer and more of a ramble than I intended, sorry.

Comment Re:Danger is known (Score 1) 357

If the gasses are heaver than air, then they might have been putting them out of the stack, or it may have been impossible to. A stack only works if you can force the gasses out, however being heaver than air, you have to heat it up (to reduce the density) to get it to go out the stack. Once it goes out the stack and cools, it might just fall down anyways.

If they vented CO2 then it would probably be hot enough to vent out of a stack. CO2 is probably classified as a poisonous gas, as it has to be at only 6%+ to cause major harm, instead of simply displacing the oxygen like a non life-sustaining gas would.

Comment Re:This is actually a bit scary (Score 1) 258

It doesn't reduce the pleasure received from playing video games, rather it works against the psychological addiction. It is already used as a smoking cessation aid. Doctors tend to be careful with depression medications given to patients under the age of 15, especially when it lowers the seizure threshold. Most parents would stop asking for it when told it can cause seizures (in ultra-high doses with patients that have a low seizure threshold naturally).

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