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Comment: Re:Wow. (Score 2) 32

by Rei (#47442911) Attached to: Rocket Scientist Designs "Flare" Pot That Cooks Food 40% Faster

Not to mention that as a mountaineer, I'd think he'd care more about cooking efficiency than cook time. And while it's great to utilize the flame energy more efficiently, there's a far more significant optimization one can do - make insulated cozies that fit your pots. Bring to a boil, shut off the heat, put the pot it in the cozy and let it cook. For my pots, I made an underpiece and a lid that fits over each other, both out of aluminized foam; it works very well.

(Of course, he could be one of those people that doesn't eat any "cooked" meals, only the "just add boiling water" meals. In that case, then I guess it's all about the efficiency of using the energy from the flame

What I want to see in backpacking is a full integrated system. Where the tent is a hammock is a backpack is a ground cloth is a pack cover is a camp chair and so on down the line, where most components serve multiple uses. When I think about how much "fabric" and "rigid structures" I carry with me that if designed properly could be eliminated, it just seems like a waste.

Comment: Re:Ted Postol very bias opinion. (Score 3, Insightful) 260

by Rei (#47440615) Attached to: A Skeptical View of Israel's Iron Dome Rocket Defense System

Actually, the key thing for them is "cheap". They need to keep costing sub-$1k missiles in the ballpark of these Iron dome systems - the more, the better. They might as well just omit the warheads to save money and increase range. Every $50k shot Israel fires with those systems costs 25 Israelis' annual tax contribution to the IDF. Every $55m system they deploy costs 27.500 Israelis' IDF tax contributions.

Palestinians are poor, but they're not *that* poor that they can't leverage those kind of lopsided financial ratios.

Comment: Re:Subject bait (Score 3, Insightful) 260

by Rei (#47440537) Attached to: A Skeptical View of Israel's Iron Dome Rocket Defense System

No, in the case of Iron Dome, that's only PR too. They're shooting $50k+ missiles at $800 rockets. Even after factoring in that Israel's per-capita GDP is 20 times that of Palestine's, that's still a losing proposition, even *if* they had a 100% hit rate (which this article is suggesting it's anything-but) and assuming that you get the launcher, radar, etc for free instead of the actual $55 million per unit. It's in Palestine's best interests that Israel deploy as many of them as possible and try to shoot down every last rocket, because every shekel they spend on Iron Domes and missiles is a shekel they don't spend on jets, tanks, and bombs.

Comment: Re:Seriously, an iphone? (Score 1) 139

by RockDoctor (#47439087) Attached to: Chinese State Media Declares iPhone a Threat To National Security
You're conflating "phone" and "smartphone". They are different things.

People can phone me and send well-crafted packets as much as they want, but they won't be able to turn on my phone's WiFi, accelerometer or GPS because the hardware doesn't exist. And I can answer work emails any time that I want to - by going home and logging into my computer and thence into the mail server. Which suits me fine - I don't want to answer work-email when I'm on leave.

Comment: Re:"Don't Worry, it's only 400k volts" (Score 1) 160

by RockDoctor (#47439045) Attached to: Hair-Raising Technique Detects Drugs, Explosives On Human Body

We've already reached the breakeven point where a suicide bomber can kill more people standing in the incoming security line of the airport than he'd kill bringing down a plane

Was there ever a time when that wasn't the case? Typical numbers queuing at my local airport (where I start or end intercontinental, but thankfully not American, flights on a monthly basis) are around a hundred, and the maximum size plane they can service is about 150~170. Since not all planes run full, it's probably always been more efficient to trigger the bomb when approaching the X-ray machines. (BTW, I think the radiation shielding in the X-ray machines will likely double up as blast containment. That's how I'd design one, anyway.)

Thinking to larger airports ... yeah, easily a plane load of people in most scanning areas, except at 3 in the morning. I seriously suspect that the security check has always been a viable detonation point. The only thing doing the plane adds is visceral terror of surviving the bomb to experience the free fall. Briefly.

Comment: That said... (Score 4, Informative) 57

by Rei (#47437451) Attached to: Sand-Based Anode Triples Lithium-Ion Battery Performance

... the greater your capacity, the less cycle life matters. If you want an EV that battery that will run a 250Wh/mi vehicle for an average 20 miles a day for 15 years, then you want it to cycle through about 30MWh. If you use a 100 mile (25kWh) battery pack, then that's 1100 cycles. If you use a 200 mile (50kWh) battery pack, then that's 550 cycles. If you use a 400 mile (100kWh) battery pack, then that's a mere 275 cycles. Actually, the improvement is even better than that in the real world, because the greater your capacity vs. how far you're actually driving, the more you can cycle the cells through a less destructive state of charge range rather than doing deep discharges.

A lot of people picture battery packs in EVs backwards, they think that things like hybrids stress the packs the least, PHEVs moderately, and EVs the worst. But it's reversed. If you look at how big hybrid packs are vs. how much electric range they hold, you'll see that they're disproportionately large, even after you factor in any differences in Wh/kg. The reason is that because hybrid packs get cycled so much, they have to keep the cycling in a very narrow state of charge range, only allowing shallow discharges. So if you only have a narrow discharge range, you have to make your pack bigger to make up for it. EVs can discharge through much more of their pack because they need fewer total cycles and only rarely go down toward the lower end of their allowable discharge range. Some EVs also let you limit the max that your pack charges up to to further extend lifespan (it's usually destructive both to use the very top end and the bottom end of the discharge range).

Comment: Re:Correct me if I'm wrong, but... (Score 4, Informative) 57

by Rei (#47437401) Attached to: Sand-Based Anode Triples Lithium-Ion Battery Performance

1024 mAhg1 is excellent capacity even vs. brand new graphite or amorphous carbon, about 3x as much as graphite's maximum. Silicon's theoretical max is 8-10x that of graphite, but the main problem with it is durability, it tends to tear itself apart on loading. There are silicon anodes in some newer li-ion cells on the market, but the tech is in its infancy.

That said, the real papers you want to be on the lookout for are cathode improvements, there's a lot more potential for volume/mass reduction there than in the anode. But it seems to be a more difficult challenge. Getting a 3x improvement in anode density is absolutely not the same a getting a 3x improvement in battery life.

Comment: Re:Little Bit of History Repeating. (Score 5, Insightful) 57

by Rei (#47437377) Attached to: Sand-Based Anode Triples Lithium-Ion Battery Performance

Commercial li-ion battery energy densities have continued to improve during that time period, including the commercial introduction of cells with silicon anodes. Of course, silicon anodes are a new tech, so there's a great deal of room for improvement, which probably won't come close to "maxing out" for a decade or more.

Of course, that said, this article is your typical fluff piece following the guidelines of fluff science reporting.

1. Present an oversimplified version of one technology challenge that may or may not address the biggest issue and certainly doesn't address all of them - but don't mention that.
2. Introduce an outside-the-establishment loner with a passion - or at least someone you can try to present as "outside the establishment" and glaze over anyone who helped him.
3. Loner gets a "vision" based on some everyday activity
4. Present their solution and make it out to be a huge revolution that will certainly solve all our problems - if they can only get corporate backing / funding!

I think these sort of articles hurt the image of science because people read them, think "OMG, all our problems are solved!", then when everything's not solved afterward, fail to trust science in the future. For example, in this case, the most important element to improve is the cathode, not the anode. And cathode improvements are less common and usually less major than anode improvements. There's also tons of different anode improvements out there in various stages of research. Pretty much all of the silicon ones get way better than graphite or amorphous carbon.

That doesn't mean that this isnt an important paper - actually, from looking at it, it looks pretty good. It's just not "all that".

BTW, anyone know how credible this journal is? I see it's hosted on Nature.com but not part of Nature, and I tried to find an impact rating for it but couldn't.

Comment: Re:Origin of life? (Score 1) 156

by RockDoctor (#47436041) Attached to: Hints of Life's Start Found In a Giant Virus
All of those questions are definitely on the table.

After the Human Genome was published, I wondered why the fuck Craig Venter went off on his boat to do shotgun PCR on random buckets of seawater. Though this work isn't directly related to that, it's marking Venter's decision to forgo the complexities of culturing organisms as being a truly inspired insight. (And I'm not even a biologist! I deal with dead things and I can see the importance of this choice.)

Comment: Re:What is life? What is a virus? (Score 1) 156

by RockDoctor (#47435935) Attached to: Hints of Life's Start Found In a Giant Virus

If life started with a giant virus, and viruses reproduce by infecting living creatures... wence life?

"Whence." Your spelling checker needs switching on.

That is one of the discussions elaborated in TFA : did viruses initially need life forms to replicate on? Or did they force the development of modern life forms. Or ... was there an earlier form of organism, distinctly different from modern cells (post-3.5Ga ago) and modern viruses (also post-3.5Ga ago) which held an intermediate position between modern cells and modern viruses?

One interpretation (NOT undisputed) is that giant mimiviruses could fill that position, and have genes old enough for the hypothesised split.

There doesn't appear to be a consensus. Which is normal for cutting-edge research.
