Catch up on stories from the past week (and beyond) at the Slashdot story archive


Forgot your password?

Slashdot videos: Now with more Slashdot!

  • View

  • Discuss

  • Share

We've improved Slashdot's video section; now you can view our video interviews, product close-ups and site visits with all the usual Slashdot options to comment, share, etc. No more walled garden! It's a work in progress -- we hope you'll check it out (Learn more about the recent updates).


Comment: Re: Not everyone (Score 3, Interesting) 78

by Firethorn (#49367275) Attached to: NSA: We Mulled Ending Phone Program Before Edward Snowden Leaks

Forced their hand? Last time I checked, they are: 1) still operating the program, and 2) tenaciously defending it.

It's a bit like the Japanese and Whaling. Turns out that the whalers operate at a loss, nobody in Japan actually likes whale meat, etc... But as long as they're under outside pressure to end the program, it becomes a matter of face to defend it.

In short, they may have ended the program since then if Snowden hadn't leaked because the program wasn't justifying itself, but now they're having to defend their illegal and unconstitutional actions, thus they 'have' to continue and justify the program in order to avoid saying they made a mistake.

Comment: Re:Well, well, well, taking about safety... (Score 3, Informative) 63

by Firethorn (#49367249) Attached to: Nation's Biggest Nuclear Firm Makes a Play For Carbon Credit Cash

...what is very little recognized worldwide, is that nuclear energy gets a free lunch at the expense of the taxpayers, as regards risk insurance.

How many other industries have more than $12B in insurance before the government will step in?

I mean, there's no other industry that could cause that much damage in a single incident, is there?

It is the most damned uninsured thing in developed countries and when one of these plants goes bust, you know what happens, ref. Fukusima.

Yeah, we're up to 2 busted nuclear plants in the whole world. All of them were old as hell plants, newer plants survived just fine, and realistically speaking we're being paranoid about the radiation.

If nuclear industry wishes to operate on-par terms with other forms of green technologies, please, bring the actuarial scientists in, to do all the math!

They have. It has even fewer deaths per TWh, including Chernobyl and Fukushima, than solar & wind

Comment: Re:Full benefits & Full responsibility (Score 1) 63

by Firethorn (#49367217) Attached to: Nation's Biggest Nuclear Firm Makes a Play For Carbon Credit Cash

Sure, just as soon as the federal government pays them back for the fees it charged while promising to take care of the waste...

Oh, and enjoy how things end up priced as we force this standard on other companies... Many of the pollutants that other companies are releasing don't break down, period.

10M years is a bit long as well - allow reprocessing and such, and you can get rid of 90% of the 'waste' by reusing it, and of the 10% remaining, you only need to keep it 'safe' for about 1-10k years, not the over 100k.

Comment: Re:WIMPs (Score 1) 218

by Rei (#49366735) Attached to: Dark Matter Is Even More of a Mystery Than Expected

In fact all forces should get weaker with distance faster in an expanding space than in flat space.

That seems like quite an assumption on your part, if I'm understanding you correctly. We can't just assume that all properties of spacetime are scaling evenly - if they did, then we'd perceive no effect at all.

But perhaps I'm misunderstanding you.

Comment: Re:Still photos (Score 1) 320

by Rei (#49366707) Attached to: Why the Final Moments Inside a Cockpit Are Heard But Not Seen

Some pilots would probably still want the ability to override the limits in an emergency if they feel that they can handle the situation better than the autopilot (for example, if the plane is crashing and the pilot wants better control over where/how to bring it down). If so, then you should make it a possibility to disable the limits, have it such that only *ground* can disable the limits. This would of course impose a delay, but at least overriding the limits would remain a possibility.

Of course, a pilot may try to trick ground into disabling limits (such as pretending to be going down or pretending to have a malfunction), so ground would need as much data as possible to assess whether the situation is legit. Might be tricky... best would be to err on the side of caution and only remove limits if everyone is absolutely sure that this is appropriate, if there's any doubt the answer should be "no".

Comment: Re:Wrong Focus (Score 1) 84

by Rei (#49366605) Attached to: SpaceX's New Combustion Technologies

Not today. But maybe in the future. If you can develop a crazy-power-dense energy source and cooling system, you could probably do it with a MPD thruster. The research I've seen on MPD thrusters operating in pulsed mode yields crazy output relative to the mass of the thruster. But you can't run it continuously because it'd overhead and take way too much power. But who knows about the future? There's the potential for extreme heat conductors like isotopically pure diamond, maybe a some kind of fission fragment reactor with a deceleration grid for power...

(of course, if you have a fission fragment reactor, at least when you're in space itd be best just to jet your fragments rather than use them to power a MPD thruster...)

Comment: Re:It is (Score 1) 84

by Rei (#49366565) Attached to: SpaceX's New Combustion Technologies

I hope they simulate propane too, not just methane. Propane has some really interesting properties as rocket fuel but have (like methane) never gotten much research. But now there's a big rush to research methane as fuel based on the concept of generating it on Mars - so propane still gets left in the dark.

Methane's ISP is only very slightly better than propane's - 364,6 vs. 368,3 at a 100:1 expansion into vacuum and 20MPa chamber pressure. But propane at around 100K (note: not at its boiling point, 230K) has far higher density (782 kg/m^3), closer to that of room temperature RP-1 (820 kg/m) then that of boiling point methane (423 kg/m^3), which reduces tankage mass and cost. 100K propane's ISP is of course better than RP-1's 354.6 in the same conditions as above. Plus, its temperature is similar enough to your LOX that they can share a common bulkhead, which reduces mass further and simplifies construction.

Hydrogen generally is the easiest fuel to synthesize offworld. Methane is generally second, and propane third. Hydrogen is often rejected as a martian fuel because of the tankage and cooling requirements. Methane can be kept as liquid on Mars with little cooling in properly designed reflective / insulated containers - but so can 100K propane, in similar conditions, but with significantly smaller tankage requirements.

It seriously warrants more research, I tell you what.

Comment: Re:When did validation actually help anyone? (Score 1) 152

What is this "regular HTML video" you're talking about? I'm talking about the new HTML5 media elements, things like <video>.

And Flash has been a viable technology for implementing these kinds of features for a very long time, and still would be had it not been deliberately sabotaged by the likes of Apple and Google for their own purposes. Ignoring your apparent personal prejudice, why objectively should I as a professional web developer not have been using such tools if they get the best results for my clients?

Comment: Re:When did validation actually help anyone? (Score 1) 152

Believe it or not, a majority of big-name sites are still using Flash, along with open-source JS players.

Exactly. Sites now have to provide the same functionality twice, because the browsers have made such a mess of standardisation that you can't rely on a single implementation to actually work portably.

It seems to me you're complaining that using new features that aren't yet standardized, aren't yet standardized. I can sympathize with your frustration, but then if you don't like it, don't use them.

Unfortunately, in the real world, that is often not an option. If your client wants multimedia elements on their site, you're going to need HTML5 multimedia elements despite the fact that numerous aspects of how they work aren't standardised. And just to be clear, this is stuff that has been available in browsers for 5+ years now. It's hardly some new development, and failure to standardise effectively after such a long period is just a demonstration of how worthless some of these standardisation processes have become.

Ultimately, what matters is whether your site works in visitors' browsers. Standards are only a means to that end, and validation in turn is only useful if you have useful standards to validate against. Since a lot of the web standards today are borderline worthless due to their instability and/or their failure to specify so many aspects that make a difference in practice, validation doesn't really give you the assurance you seek of compatibility either across today's browsers or with future browsers.

Once again, I'm not saying the world wouldn't be a better place if you did have that assurance or that I agree with the path the browser makers and standards bodies have chosen to follow. I'm just saying that as a web developer you have to play the cards you've been dealt, and I don't see formal validation as improving your chances to any useful degree today.

Comment: Re:QuikClot and Celox (Score 1) 70

If this technology becomes common place, I expect those with crustacean allergies will be required to wear a red tag same as those with pencilin allergies.

It might even become practice to use it anyway and follow up with a treatment for the anaphylaxis, if the bleeding is severe enough. People can survive shellfish reactions with management - severe internal bleeding, not so much.

Comment: Re:The value of technology investment (Score 1) 84

by bill_mcgonigle (#49365579) Attached to: SpaceX's New Combustion Technologies

This is the first article I've seen that explains well how GPUs can/are being used for practical applications along with what can be achieved and some of the issues.

GPU's have been used for all sorts of "practical" computations for half a decade now, but the really interesting part here is that CFD has been particularly GPU-resistant using existing algorithms. See the Xeon Phi processor, etc. for non-GPU approaches to throwing dedicated hardware at the problem. It's easy to underestimate the enormity of this quote, but "starting from scratch" when necessary is something SpaceX excels at:

I am grateful to SpaceX for allowing us to basically start from scratch on CFD and in many ways reinventing the wheel.

It's hard to gain sufficient insight from TFA but it sounds like this is as big as hidden-line-removal in computer graphics and that they've moved CFD to the boundary conditions and made that GPU-computable, which is like solving two or three orders of magnitude at once.

Great spirits have always encountered violent opposition from mediocre minds. -- Albert Einstein