Comment Re:I'm sure this is just poor wording... (Score 3, Informative) 171
That the models predict an amount of lithium with narrow error bars.
It's a really neat prediction, it just happens not to agree with the measurements.
That the models predict an amount of lithium with narrow error bars.
It's a really neat prediction, it just happens not to agree with the measurements.
Since the cars drive 11 mph according to TFS the bikes are the fast ones. They have to limit their speed to match the slow cars.
The pedestrians are even slower than the cars so the speed delta is bigger for bike-pedestrian accidents.
Besides, dunno about the US but here the sidewalks are often paved with 30x30 cm (1 footx1 foot) concrete tiles. Those are unsuitable for bikes because they are just not flat enough.
'Round here (NL) better bike paths do usually increase speed for cars, because a percentage of drivers start biking. Then there are less cars on the road and thus less congestion.
Thank you. At least there is one who reacts like I do.
Dump soil on coral reefs to make islands is evil. Especially for such a stupid reason.
Why are you proposing to build islands at a nanometer scale?
Helium leaks slowly through a fully welded vessel. Really slowly.
If they use fully welded vessels the leak rate is around 10^-12 mbar*l/s. That means half the helium will be gone in approx 5 million years.
I really should have done the calculations before posting that. It takes almost 5 million years to lose half of the helium, assuming a proper weld.
Helium loss is no issue.
Calculations are in my reply to this post
Still, that is approximately what happens.
Partial pressure put simply:
Forget absolute pressure. What matters in leaks is the pressure of each gas individually.
There is 0.00052% of He in the atmosphere. Assuming 1 bar of absolute pressure this means there is a partial pressure of 0.0000052 bar of helium in the atmosphere.
If the drive is filled with 1 bar absolute pure helium the difference will be 1-0.0000052 = 0.9999948 bar. That is the pressure that is important. There is no way the helium will not leak out. There is no such thing as a closed system. The system will also leak air in but far less. The result is a vacuum in the drive. In the end that vacuum will be filled with air but that takes far slower.
Now how long will the loss of helium take?
A 3,5 inch drive is about 0.3l. I assume that half of that is filled with hardware so I assume 0.15l He. A properly welded system without any connectors is probably in the range of 10^-12 mbar*l/s He leak tight. If I assume the drive will work at 0.5 bar helium we can take 10^12*500 mbar *0.3l = 150 * 10^12 seconds.
A year has 3.15 * 10^6 seconds. That is almost 5 million years. Not really something to worry about.
Yes there is a leak. Yes the helium will escape. No it doesn't matter because it just takes extremely long.
With a bad weld the time would drop significantly. However, the detection is easy. Helium leak detectors are commonplace, to detect minute leaks in high purity systems.
Sources:
Dimensions drive: Wikipedia.
Leak rate: I can get connectors to 10^-11 as standard items (Swagelok VCR full metal seal). Fully welded systems are probably better than that.
When the helium is gone the drive will be high vacuum. The drive should include a breakaway disk (with shrapnel filter) to prevent collapsing of the enclosure. The system should detect that break and slow down the drive to 5400 RPM to fail gracefully.
SMART should report the pressure inside the drive and the status of the breakaway disk.
Then you can get the data off while the drive is in degraded mode.
Those subterranean sources are being replenished by natural alpha emitting sources.
When those sources are gone the sun will have gone red giant, absorbing the earth. We should have enough helium by then.
1. Generate all electricity from nuclear sources.
2. Store the alpha emitting waste in a capturing facility.
3. Wait for the alpha particles to encounter electrons (shouldn't take long)
4. Siphon the generated helium off.
5. Purify sufficiently.
6.
7. Profit.
Short commutes suck on public transport. The travel time to bus stops is often far too long.
10 minutes by car seems to be suitable for a bike commute, if the untold circumstances allow it and you feel like it.
You really don't want the mass of a battery on top. Have you ever driven in a bus? The drivers really throw them around. Having all that mass on top would cause quite a few to be tipped over.
We detect the particle spray that they start when they hit the upper atmosphere.
1. Although alcohol based hand sanitizers work reasonably well against germs (mostly viruses and a few types of bacteria), they generally need 15-30 seconds to do their job well enough. You generally don't touch a door handle that long, nor is it likely to glop enough on to your hands to meet that threshold.
It's not to clean your hands. It's to keep the doorknob germ free.
Hand sanitzers mostly work against bacteria and not so much against virusses. They also don't do much more than regular washing with soap (sanitizer kills 99,9% of the bacteria with 30 second application while washing with soap cleans approx 99%). Regular washing with soap works much better if there is visible dirt on your hands. Hand sanitzer will not remove that, just spread it out.
FWIW, a more mainstream technique is to use special metal alloy door handles. Although they only work on bacteria, they are at least a known proven method
I can only agree with that.
Neither method will work efficiently against a viral respiratory infection though.
"Look! There! Evil!.. pure and simple, total evil from the Eighth Dimension!" -- Buckaroo Banzai
