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Comment: Re:Just moves a choke point (Score 1) 395

by mrvan (#48147597) Attached to: Battery Breakthrough: Researchers Claim 70% Charge In 2 Minutes, 20-Year Life

Aire de Berchem is Luxembourg is (according to Dutch wikipedia) the busiest gas station in the world (mainly because Luxembourg has the cheapest gas in the region and it is on a number of busy roads). It pumps 850.000 liters per day, enough to fill up 17000 cars*. If every car needs 70% of 85KWh, this requirs 85k * .7 * 17k = 1GWh per day. If they can spread perfectly over the day, it means they need a 50MW power plant, which I guess is not too far out there. This will probably require some impressive capacitator / battery setup to get enough peak power though, no clue if something like that is feasible.

(the total amount of energy in 850k liters of gasoline is 42.4 MJ/kg * 0.77 kg/L * 850kL = 27 TJ = 7.5GWh. So it seems that the total efficiency of electric cars is about 8 times higher, assuming equal range, which is probably false. But a factor 5 might be around right...?)

*) the wiki mentions it's 80% diesel, and while diesel cars are pretty common here, I would assume that means that the majority of liters goes to trucks. Now suppose your Tesla truck with 500KWh needs to charge in 5 minutes....

Comment: Re:Wow (Score 1) 134

by mrvan (#48080717) Attached to: Google's Security Guards Are Now Officially Google Employees

Our cleaning is outsourced and the cleaners generally have little command of the local language. I know most of them by now, however, and have a little chat when I can. I leave my wallet and phone on my table if I go grab a coffee to allow them to clean my office (I work late a lot of times). Nothing untoward ever happened and I've not heard any of my colleagues complain.

Comment: Re:Proper Science is hard. (Score 4, Informative) 795

by mrvan (#47966195) Attached to: How Our Botched Understanding of "Science" Ruins Everything

Scientist here - by geekoid's definition at least.

Scientists use jargon for the same reason sailors do - to efficiently communicate a very specific concept. In a sailing vessel at sea in a storm, you really don't want to take a minute to explain that you mean the green-white striped rope that connects the beam to the hull - you say mainsheet*.

Now, there is a lot of nonsense going on in science, with ridiculous performance metrics, a discouragement of actually innovative high-risk research, a sometimes religious worship of established names and theory; and a lot of stuff gets published not because it is particularly innovative, enlightening or even robust, but because it uses the right buzz words and cites the right people. However, that does not make science as an endeavour less wortyh - it's a bit like** how democracy is a good idea even if a lot of politicians (the ones in high places, at least) are dodgy.

* if my English sailing jargon is correct - not a native speaker
** my next analogy will be about cars, I promise

Comment: Re:A Little Perspective (Score 3, Interesting) 14

by mrvan (#47823829) Attached to: Ireland To Host Robotic Sailing Championships

This doesn't matter that much. Larger yachts sail more or less the same as smaller yachts; the main effect is that all forces are multiplied. For humans this makes a lot of difference: needing winches instead of pulling ropes by hand, being hit by the boom during a jibe changes from unpleasant to lethal, the ability to push off against the wall is greatly diminished, etc. For automatic sailing, however, the main effect will probably be cost rather than difficulty, as none of those factors are really important until material strenght becomes a problem. Smaller boats can even be more difficult to handle since the intertia is smaller compared to the wind forces (mass is cube of size, wind area square), making a smaller boat less stable.

Comment: Re:is it better than random? (Score 5, Informative) 177

by mrvan (#47621371) Attached to: Algorithm Predicts US Supreme Court Decisions 70% of Time

That is correct, but not what the GP meant. If you can model the distribution (e.g. you 'know' that B is 90%) then you can weigh your random guessing such that it is correct in >50% of the cases, even without looking at the case itself (it is still 'random' in that sense)

Extreme case: I can predict whether someone has Ebola without even looking at them with >99.99% accuracy by just guessing "no" every time, since the prevalence of Ebola is >.001%.

Suppose the supreme court has 70% chance of overturning (e.g. because they choose to hear cases that have 'merit'), then an algorithm that guesses 'overturn' 100% will have a 70% accuracy. A random guess that follows the marginal of the target distribution (e.g. guess 70% overturn) also scores >50% (58% to be precise).

Comment: Re: Is it still braindeadly single-threaded? (Score 1) 138

by mrvan (#47414111) Attached to: Dwarf Fortress Gets Biggest Update In Years

embarrassingly parallel has a specific meaning, namely that the task is composed of a (relatively large) number of sub tasks that can each be performed completely independent of each of the other sub tasks. So, any sane attempt to pathfind (say an A* search) is not embarrassingly parallel since whether a path can be pruned depends on the best paths found so far in other branches, and there is an optimal ordering for which branches to descend into first which is also dependent on what's happening in the other branches. I'm sure you can make a parallel version by e.g. forking out N possible branches to some depth, gathering state, and then pruning and ordering centrally and branching out again on the most promising branches, but this is not "embarrassingly" parallel.

Comment: Re: Is it still braindeadly single-threaded? (Score 3, Informative) 138

by mrvan (#47413845) Attached to: Dwarf Fortress Gets Biggest Update In Years

For one unit, sure. The CPU problem in DF (as far as I understand) is that there are 200 dwarves, 100 goblins and 400 kittens all trying to pathfind at the same time. Unless I miss something, each of these units van pathfind in parallel since they don't "know" about the other's paths.

There's a whole WORLD in a mud puddle! -- Doug Clifford