Become a fan of Slashdot on Facebook


Forgot your password?
DEAL: For $25 - Add A Second Phone Number To Your Smartphone for life! Use promo code SLASHDOT25. Also, Slashdot's Facebook page has a chat bot now. Message it for stories and more. Check out the new SourceForge HTML5 Internet speed test! ×

Comment Re:Batteries (Score 4, Informative) 514

Lead-acid batteries typically last well under a thousand cycles, and also deteriorate if you deep cycle them. Thus you'd probably need to replace a car battery solution every couple of years.

This isn't all that much better though. I don't think they have released the actual specs, but these batteries are likely to have a cycle life of around 3000 (which is consistent with the 10 year guarantee as they are unlikely to have a full cycle every day). This is much better than lead-acid, but as you say they are also much more expensive.

Comment Re:Ugh (Score 1) 473

Which is exactly what the paper is about: the trapezoidal rule which it has 'invented' is equivalent to drawing straight lines through the points (pretty much the simplest curve you can get) and integrating.

There are indeed better ways of doing it, but what's interesting is that the paper claims researchers were using techniques that were even worse.

Comment Re:And he needs a computer to do it for curves (Score 2, Informative) 473

This isn't integration. This is a numeric technique for estimating the area under the curve (the trapezoidal rule). This is a somewhat different branch of mathematics to integral calculus, which deals in the infinitesimal limits to provide exact results. You can't use integral calculus here, as there is no formula to integrate, only experimental results.

It looks like this area is indeed in need of some interdisciplinary communication: what they really need is for a statistician to come up with a robust formula for this taking into account the errors.

Comment Re:Ugh (Score 4, Interesting) 473

Actually, from the abstract this looks like a moderately interesting paper. Also note that the slashdot summary is (as often the case) wrong. You can't solve the problem the paper is referring to with integral calculus.

The curve that the paper is talking about is an experimental result, not a formula. All you have are the experimental samples from the curve. Without a formula, you CAN'T do integration, and must rely on a numerical technique. What he's 'invented' here is the trapezoidal rule. He'd do even better with something like Simpson's rule, but that might be impossible to apply if the sample points are not evenly spaced. Similar problems occur for the various Runge-Kutta methods.

Although the numerical technique that claims to be invented here is indeed a basic numerical technique, the paper is interesting for pointing out that the even cruder numerical techniques that have been used before are overestimating the curve area, and that is an interesting result.

Comment Re:Yes, SHA1 security is questionable.. (Score 1) 217

Because it has become easy to create 2 plaintexts that both hash out to the same SHA-1 value. See the section titled "SHA-1" which talks about attacks on the hash function.

Um, the very article you link to lists no found collisions, only theoretical attacks (where an algorithm could be used to find one faster than a brute force search).

Given that I've yet to see an actual SHA-1 collision published, it's hardly "easy" to do...

Comment Re:Hopefully... (Score 1) 229

The problem with the FireSheep discussion is that there is no current solution to this.

People keep saying that the social media sites should use https. However, they CAN'T use https for the entire session: advertising content delivery networks like AdSense don't support https, so it won't work.

Comment Re:What I don't get (Score 1) 229

As I've mentioned in other messages, this is the real problem. Advertisements can't be served over https as the major networks like Google's AdSense don't support https. This is exactly the kind of third-party content you mention.

So sites that are funded by advertisement will use http not https.

Comment Re:What I don't get (Score 1) 229

This kind of thing is the fundamental problem. Interoperability issues like this are why the major advertising content delivery networks (including Google's AdSense) don't support https.

As they don't support https, social media sites can't use https for the entire session as they wouldn't be able to serve ads, and so wouldn't make any money.

So we get insecure social media sites, as these are the only ones that can stay in business.

Slashdot Top Deals

Space is to place as eternity is to time. -- Joseph Joubert