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Sir Richard Branson Quietly Shelves Virgin Submarine Plan

wagnerrp Re:Can't say I'm surprised (47 comments)

Branson has a track record of seriously underestimating the difficulty of the challenges he picks. Plus he seems to believe he can replicate serious engineering achievements - eg space flight - on a shoestring budget.

You're overestimating the capability of SpaceShipOne/Two. It goes to space for all of a couple minutes. It does not go to orbit. The engineering requirements aren't nearly as tough. We've been sending unmanned vehicles up there since the early 40's, and manned ones up since the late 50's, back when NASA was still called NACA.

3 days ago
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Sir Richard Branson Quietly Shelves Virgin Submarine Plan

wagnerrp Re:No so easy as throwing money at it, is it? (47 comments)

The Apollo programme was 4% of GDP, by itself

The Apollo program cost ~$20B, over the better part of a decade, during a time when the US GDP was rose from around $600B to $1T. So, it used roughly 0.3% of the GDP over that time period.

3 days ago
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High Temperature Superconductivity Record Smashed By Sulfur Hydride

wagnerrp Re:Oh Carbon (80 comments)

There's even a type of energy storage system you can make with superconductors - one of the highest power density and efficiency energy storage methods known to man.

The ultimate capacity of one of these systems is on the par with supercapacitors, and an order of magnitude lower than traditional chemical batteries. Their high power, low capacity, and functionally unlimited cycle life make them useful as a transient power filter, rather than a meaningful energy storage mechanism. Their sudden and nearly instantaneous quench makes them downright frightening as a sizable energy storage mechanism.

about two weeks ago
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Material Possiblities: A Flying Drone Built From Fungus

wagnerrp Re:Fungi as instruments (52 comments)

You're suggesting that instead of giving it some simple sensors and a radio, we task a satellite capable of real-time spectrographic imaging with sub-decimeter resolution in order to spot the changes in color of some oversized flying test strip?

about two weeks ago
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Who Needs NASA? Exoplanet Detected Using a DSLR

wagnerrp Re:Billions and billions: (108 comments)

This site is based in the US. Therefore, the convention it follows should be that of the US. Any use of a comma as a decimal delimiter here is simply wrong.

Besides that, the use of six digits when only two or maybe three are actually significant is just clumsy.

about two weeks ago
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Fly With the Brooklyn Aerodrome (Video)

wagnerrp Re:Shrug... (22 comments)

Except those things mostly have real airfoils, and don't need such a high TWR to plow through the air like the flat plate in the article.

about three weeks ago
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Denmark Faces a Tricky Transition To 100 Percent Renewable Energy

wagnerrp Re:Use the money you save (488 comments)

Like I use energy to lift a stone, and I get 100% of that energy back if the stone drops.

No body is fully elastic. You will have infinitesimally small energy losses due to changing internal stresses in the two bodies. You get very very close to 100% recovery, but not 100% recovery. The energy is still there. It hasn't escaped your hypothetical closed system. It is simply not recoverable in a useful form. It is disordered. Reversible processes are those "special cases".

about a month ago
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The Downside to Low Gas Prices

wagnerrp Re:Stupid, trucks cause the problem (554 comments)

Of course doing so has the side effect that no one will give you loans because your currency is too unstable to be of any international value.

about a month ago
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The Downside to Low Gas Prices

wagnerrp Re: so why specifically target drivers? (554 comments)

Those numbers already take into account the difference in traffic volume. An individual loaded tractor trailer causes several thousand times the damage as a single sedan. In other words, there would have to be 80x the volume of passenger traffic on the road to cause the same amount of damage as present truck traffic.

about a month ago
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The Downside to Low Gas Prices

wagnerrp Re: so why specifically target drivers? (554 comments)

Doesn't matter much, it's the same people that drive their cars that also buy supplies that require trucking.

So what? You're artificially buoying up industries that perhaps shouldn't be. Nearly all of our shipping is done over the road, due to cost and convenience. Make roadway shipping pay to repair its fair share of damage done to the roadway. Initially, shipping costs will rise. Costs for all products would rise across the board as those increased operating costs trickle down to consumers. Over time, those companies will find new ways to reduce costs. Money would be pumped into the rail system, expanding and modernizing it to improve speed and throughput. Manufacturing would become more regionally diverse so less has to be shipped across the country. Fewer vehicles on the road means lower traffic congestion. Less roadway maintenance further means lower traffic congestion. Locomotives are more efficient per unit of shipped material are more easily managed in terms of emissions. Fixed, limited access railways can be more easily converted to electric.

The trucking industry would suffer, unquestionably, but it's a much more complicated issue than you give it credit for, and perhaps the advantages in other areas outweigh those effects.

about a month ago
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The Downside to Low Gas Prices

wagnerrp Re: so why specifically target drivers? (554 comments)

Semis burn 5x more fuel yet cause 80x more damage.

Is that taking into account traffic volume, as a typical loaded tractor trailer is going to cause several thousand times the damage as a typical sedan.

about a month ago
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Boeing Readies For First Ever Conjoined Satellite Launch

wagnerrp Re:So, ion drive or something??? (67 comments)

You would need a nuclear reactor to provide enough power to land on the Moon using an arcjet.

about a month ago
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Denmark Faces a Tricky Transition To 100 Percent Renewable Energy

wagnerrp Re:Use the money you save (488 comments)

Electrolysis has nothing to do with thermodynamics

By that, you actually mean everything has to do with thermodynamics. You're adding energy to disassociate a molecule. Thermodynamics dictates that you cannot recover that same amount of energy by letting the constituent elements recombine. Tyr07's uncertain belief coincides with one of the fundamental principles at play in any real world system.

Fuel cell efficiency varies greatly, it goes up to 85% for current marketed high temperature hydrogen fuel cells.

No it doesn't. The only way you could hope to achieve anywhere near that is through some combined cycle process that scavenges waste heat from the fuel cell. You might find some experimental units pushing 70%, but anything commercially available is going to be under 60%.

Total cycle efficiency is going to be under 25%. That is complete nonsense, you must be bad in math.

Assuming realistic values for electrolysis and fuel cells, you're already well under 40%. Depending on your compression ratio, you're only likely to recover 50-60% of the energy spent compressing the hydrogen for storage, so that's either higher losses, or higher capital costs for storage volume. Tack on a couple percent for leakage, and 25% is very reasonable.

about a month ago
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Denmark Faces a Tricky Transition To 100 Percent Renewable Energy

wagnerrp Re:Use the money you save (488 comments)

The energy required to compress and cool the hydrogen into a liquid in the first place, as opposed to just larger, less insulated, high pressure gas tanks, would more than offset any gains made by using the boiloff to cool your data center.

about a month ago
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Denmark Faces a Tricky Transition To 100 Percent Renewable Energy

wagnerrp Re:Use the money you save (488 comments)

conversion ratio wise I believe it takes more power to produce the hydrogen than it returns so there is a loss

Yes. Electrolysis does not violate the laws of thermodynamics. What I assume you were getting at, electrolysis usually runs around 50-60% efficiency and fuel cells range from 30-70% depending on the chemistry, and in practice since you have to store it, you also have to factor in compression losses, hydrogen leakage, and burners to bring your decompressed gas back up to the operating temperature of your fuel cell. Total cycle efficiency is going to be under 25%.

about a month ago
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Denmark Faces a Tricky Transition To 100 Percent Renewable Energy

wagnerrp Re:Are renewable energy generators up to task ? (488 comments)

You can expect about 900kWh yearly per 1kW of typical solar panel installed in Denmark. Therefore it takes an installed capacity of 240GW of solar panels to cover Denmark.

That makes the assumption that your daily average production and consumption is anywhere close to your yearly average, or that you have an absolutely massive energy storage system capable of storing hundreds of petajoules to last the winter months.

about a month ago
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New Atomic Clock Reaches the Boundaries of Timekeeping

wagnerrp Re: Old saying (249 comments)

Because it would be meaningless to "compensate" for the time difference between clocks moving and accelerating differently. Time literally moves at different rates in different reference frames. The clocks are correct; the problem is that the concept of similtaneity is fundamentally flawed.

I'll admit, I don't understand why the arbitrary reference time we use currently is any less valuable now that we have surface clocks whose real time is measurably changing due to relativistic effects.

about a month and a half ago
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New Atomic Clock Reaches the Boundaries of Timekeeping

wagnerrp Re:Old saying (249 comments)

Why can't we compute what the relativistic slew rate between two different locations will be and compensate?

about a month and a half ago
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Virgin Galactic SpaceShipTwo Crashes

wagnerrp Re:Not a good week... (445 comments)

So someone who straps a couple homemade AP motors to the side of an ultralight qualifies as well? (One could argue doing such a thing would preclude them classification as an ultralight...)

They're daring, sure, but they're not pioneering new territory, as we did this over 50 years ago; they're just making it cheaper. Even when they do get there and make it cheaper, there's no way to expand upon its capabilities without a complete from-scratch redesign. They're not enabling anything further. Unless they directly expand science, industry, or medicine, or indirectly provide the tools for others to do so, they're not benefiting society, just themselves personally. Being a hero implies acting for the benefit of someone other than one's self.

about a month and a half ago
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Virgin Galactic SpaceShipTwo Crashes

wagnerrp Re:Using NASA's dictionary (445 comments)

To be fair, we already reached that specific frontier over 50 years ago.

about a month and a half ago

Submissions

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MythTV 0.24 Released

wagnerrp wagnerrp writes  |  more than 4 years ago

wagnerrp (1305589) writes "Following with the accelerated development schedule, MythTV 0.24 is now available six months after the release of 0.23. MythTV is a distributed Linux-based PVR and home theater application. Highlights of this release include a brand new theme-able playback OSD, playback of HD audio formats, multichannel and 24/32-bit audio output, Bluray playback, and multi-angle DVD playback. A full listing of changes is available on the MythTV wiki."

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