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Comment: Re:It's almost like the Concord verses the 747 aga (Score 1) 149

by Rei (#49158079) Attached to: Hyperloop Testing Starts Next Year

zblockquote>See: Cabin_Pressurization [wikipedia.org]

A person needs at least 20kPa *from the mask to breathe*. Not 20kPa *ambient pressure*. Please learn to read.

The "problematic loading on the capsules" is from the high speed aerodynamics, not the ambient pressure

Aerodynamic loading = pressure. If you have high loadings, you have high pressures. Period.

Comment: Re:Best defense is not to care (Score 1) 82

by peragrin (#49157901) Attached to: Blu-Ray Players Hackable Via Malicious Discs

I was using my samsung Smart tv for youtube, as Roku didn't have a youtube. That changed ~6 months ago so I started to use both. Then Samsung tried to insert ads into my playback , so I disconnected the TV from the network.

What will it take for companies to learn if you don't want to provide support for 10 years don't design a device that requires your constant support for 10 years?

Comment: Re:Whiteboards and whiteboarding are a bad idea. (Score 1) 141

by gl4ss (#49157577) Attached to: Ask Slashdot: Whiteboard Substitutes For Distributed Teams?

yeah it's always bad when vocal participants like the client(product owner whatever) wants to add complexity to actually make the product do what it is supposed to do..

and if you actually make an uml diagram that results in hundreds of thousands of lines of java code that does the same thing as 100 lines then you have fucked up quite badly in both making the uml diagram and writing the code.

I think the OP was asking for a solution to do just high level design anyhow, to slash up the work into smaller logical segments - so that they don't end up writing hundreds of thousands of lines of unnecessary code.

a whiteboard is useful that you can draw anything on it.
like drawing the flow of the program from ui side for example to communicate to the team what the end product needs to do so the team can figure out what the backend has to be capable of and so forth. if that part is skipped the server guys can for example write some shit that they claim fills the role of the server but is fucking horrible at doing what it needs to do and ends up needing a total rewrite before the product can ship.

Comment: Re:Foxconn Factories' Future: Fewer Humans, More R (Score 1) 115

by gl4ss (#49157561) Attached to: Foxconn Factories' Future: Fewer Humans, More Robots

they're living in poverty while working for foxconn too so whats the difference?

at least now they'll be hiring more decent engineers. the only reason they were using human labor in the first place in such amounts and in such boring easily automated tasks was that they lacked decent manufacturing engineers. in other words it was cheaper(or easier in their work culture) to hire 40 guys to put in screws instead of hiring 1 decent guy to first make a jig for the work and 1 guy pressing the button to do the work.

Comment: Re:It's almost like the Concord verses the 747 aga (Score 1) 149

by Rei (#49157171) Attached to: Hyperloop Testing Starts Next Year

What sort of claim is that? Since when do oxygen masks need 20kPa to function? And secondly, if there's "problematic loading on the capsules" from too much pressure on the pressure-compromised capsule, then your pressure is also way too high inside. Which means that you've repressurized the tube way too much. So the solution is: Don't do that!

Comment: Re:It's almost like the Concord verses the 747 aga (Score 1) 149

by Rei (#49157159) Attached to: Hyperloop Testing Starts Next Year

Branching at full speed is probably not possible with the Hyperloop as designed; the skis are curved to match the diameter of the tube, with a ~1mm clearance with the tube surface, so there is no passive tube design that could accommodate a "switch". In order to continue from Section A to either Section B or Section C, you'd have to make an intermediate length of tube several hundred meters long that could be physically moved at one end from B to C, with sub-millimeter precision

Wait, meaning that while it's technically possible, but it'd be really tricky to accomplish? Gee, I wish I had written something like "Branching would be really tricky, but there's no physical barriers" at the top of my post ;)

The reason is threefold: drag continues to increase at higher speeds regardless of the speed of sound

Drag is reduced in the first place by using hydrogen even at a given pressure. And you can use 1/4th the pressure and still maintain lift because you're moving four times as fast. And given how few reboosts are needed from LA to SF in the base case, a few more per unit distance hardly seems limiting.

If you consider that the steel Hyperloop pipe draped across 30m-spaced pylons will approximate a vertical sine wave, then at 700mph the allowable sag is only about 5cm

Irrelevant because earthquakes impose far more deflection that you have to be able to counter (and that the proposal calls for countering) than a craft moving past.

Mechanical braking from 1500mph in the event of an emergency is also a non-starter

What, you're picturing drum brakes or something? You're moving at high speeds in a giant steel tube. Magnetic braking couldn't possibly be easier.

a 700mph capsule will incur about 2g's of aerobraking deceleration

Where are you getting this from? Even if the tube was instantly full pressure (which it wouldn't be), a streamlined shape will not experience 2Gs at 700mph, any more than a passenger jet losing full engine power does. And anyway, 10g horizontal is not fatal even if that was the case. The average untrained individual, properly restrained, can tolerate 10g for a minute without even loss of cognitive function.

Comment: Re:It's almost like the Concord verses the 747 aga (Score 1) 149

by Rei (#49157121) Attached to: Hyperloop Testing Starts Next Year

Not only that, but if your craft is travelling four times as fast, you're sweeping through four times as much gas per unit time to compress under the skis.

Hydrogen has all sorts of advantages. And the very low pressures prevent most of the negatives. The only one that I don't know about and would require testing would be what sort of reaction would one see as a craft moves past, with any residual oxygen. If I had to guess, I'd guess that you will get some combustion, but the craft moves past so fast and the mixture will decompress so fast, I would think the rate would be quite limited.

Comment: Re:It's almost like the Concord verses the 747 aga (Score 1) 149

by Rei (#49157115) Attached to: Hyperloop Testing Starts Next Year

First off, if servicing that requires full de/repressurization is some sort of frequent event, then the whole concept is doomed for reasons entirely unrelated to anything in this discussion. Secondly, 1/5 ton of hydrogen at industrial rates is about $200. Whoop-di-doodle-doo. And the advantage is being able to travel at mach freaking 4, not about the reduction of drag at a given speed (which is, FYI, true also).

Comment: Re:It's almost like the Concord verses the 747 aga (Score 1) 149

by Rei (#49157107) Attached to: Hyperloop Testing Starts Next Year

As someone else already mentioned, it uses low pressure air because the "trains" are ground-effect aircraft, not maglev. They need air.

Secondly, the pumping budget to overcome leaks is so small, both in terms of capital and ongoing costs, that you could increase them by an order of magnitude and not have any sort of practical effect on the budget. Whatever factor you increase over the baseline increases the factor you can replace air by. You don't need 100%.

Comment: Re:It's almost like the Concord verses the 747 aga (Score 1) 149

by Rei (#49157097) Attached to: Hyperloop Testing Starts Next Year

You think keeping hundreds of miles of tubing is really going to be cheap? Go look at a highway budget sometime.

Because Hyperloop is a highway? The closest analogy is a pipeline. Except that the environmental hurdles for building an oil pipeline raise the cost dramatically. Yet Musk's budget in Hyperloop Alpha is well higher than that of an equivalent diameter per mile.

Then consider ... Then consider ... Then consider ... Then consider...

And when you're done with that, then consider that every last thing you mention here was analyzed in detail in the Hyperloop Alpha proposal, which you apparently never read.

Byte your tongue.

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