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Comment: Re:This guy has a better idea (Score 1) 221

by Michael Woodhams (#49208569) Attached to: New Concept Tire Could Recharge Car Battery

How about using supercapacitors to convert 5 seconds of 60kW into 15 seconds of 20kW (less losses)?

5 seconds of 60kW = 300kJ. Supercapacitor energy densities are in the range 0.5 to 15 W-hour/kg according to Wikipedia. Say 5 Wh/kg, = 18000 J/kg, so you'd only need a few kg of supercapacitor to make this work. The only price I find is US$2.85 per kJ in 2006, putting the cost at around $1000, probably much less now (but there will also be costs beyond just the supercapacitor.)

You could also make this an option - not much point paying $2000 for this capability if the car is going to be in Singapore.

Comment: Re:Why can't they fairly negotiate? (Score 1) 61

I can't tell if you're serious.

The idea of landing a stage on rocket power for reuse has been around for decades (DC-X comes to mind, there may be earlier examples.) As rockets generally launch seaward for safety reasons, that you might want to land one at sea is obvious. The idea of using a ship as a landing platform has also been around for decades. There is nothing that should be patentable in the big idea "landing a rocket on a ship".

Within this general idea, there are bound to be many smaller patentable ideas: e.g. method for automatically securing a rocket to a deck when it could be up to 15m away from the target landing point.

Comment: Re:International waters (Score 3, Informative) 61

Furthermore, that is why rockets launch from the east coast in the first place: if something goes wrong, the flaming debris comes down over the sea.

However, SpaceX are aiming to do a return to launch site for recovering their stage I boosters. (This surprised me - this must use more fuel than land-at-sea, and the mass of that fuel is directly subtracted from your available stage II payload.) The landing at sea is an interim measure while they prove the technology (because of the afore mentioned potential for flaming debris.)

Comment: Instantaneous launch window (Score 1) 75

Also: both this launch and the previous one (space station resupply mission) had an "instantaneous launch window", meaning that any delay at all means they scrub for the day. Why is that? What is so magical about their launch time that they can't accept a one minute delay? And how much does it cost to scrub a launch for a day?

Comment: Where do I go to get news about these launches? (Score 1) 75

Just yesterday I looked at the SpaceX website's news page specifically to find out when the next rocket recovery attempt would be, and it said nothing about this. I just happened to check /. in time to tune in to Nasa TV 5 minutes before launch time. (Incidentally, they've scrubbed the launch for today.)

Comment: Re:Great to see (Score 2) 152

by Michael Woodhams (#48800243) Attached to: Chinese Spacecraft Enters Orbit Around the Moon

A minor nit-pick: I think you mean "chemical rocket".

Probably the most common rockets are liquid hydrogen/liquid oxygen. Neither are fossil fuels. Solid rockets could contain oil-derived plastics in their fuel, I don't know enough to say how often this is so. SpaceX uses kerosene/liquid oxygen which does use fossil fuel, although I expect it wouldn't be hard to substitute a suitable biofuel if they really wanted to.

Comment: Re:Great to see (Score 5, Interesting) 152

by Michael Woodhams (#48799757) Attached to: Chinese Spacecraft Enters Orbit Around the Moon

Since 1969 there have been people living on Earth who have visited another world. It would be a terrible failure of humanity if one day this was no longer true. I am not fond of the Chinese government, but if they send people to the moon, I'll be enthusiastically cheering them on.

Comment: Re:Rock paper scissors (Score 1) 340

If game theory mathematicians say they've got a strategy which provably can't be beaten, I'll believe them until someone finds a flaw in their method. Mathematicians are notoriously picky about what constitutes a 'proof'. I'm sure they are quite aware of the possibility of an opponent which knows their strategy and adapts to it. (Note that in the rock paper scissors example, knowing the perfect strategy does not let you beat it.)

The article does not specify whether the strategy is deterministic or probabilistic. I expect the latter: sometimes its big lookup table will say "in this situation, raise 15% of the time, fold 85% of the time."

Comment: Rock paper scissors (Score 4, Insightful) 340

by Michael Woodhams (#48771147) Attached to: Researchers "Solve" Texas Hold'Em, Create Perfect Robotic Player

You can better understand what is going on by considering the much simpler game Rock paper scissors. 'Perfect' here basically means the strategy gives you the best possible worst case.

For RPS, the perfect strategy (using the term in the same sense as it is used for the poker bot) is to play completely randomly. There is no way to gain an edge over this strategy, no counter-strategy which will give you more than 50% chance of winning, even if you know your opponent's strategy. (In this case, there is also no strategy which will give you less than 50% chance of winning against the 'perfect' strategy.)

For the poker bot, there is no strategy that will give you greater than 50% chance of winning against it in a two player game. If you know its strategy perfectly (but of course you don't know its cards) the best you can do is to equal that 50% chance (which is what happens if it plays itself.) Unlike RPS, you can can lose to the perfect poker bot by playing poorly. Also, as noted in the article, the perfect poker bot always plays as if it were playing against perfect opposition. A good human player will fleece you faster then the perfect bot, because the human player will notice your peculiar imperfections and exploit them, choosing to play in a way which would be suboptimal against a perfect opponent, but superior against you.

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