Frank

On 12/3/2018 at 10:03 PM, J.C.MacSwell said:

Very good point, but is that not an argon bottle?

Your post reminded me of that tragedy and I thought it was important to mention, especially on an open forum.

14 hours ago, StringJunky said:

Probably best to warm the tank on the outside first to let the gas/petrol escape into the interior from the wall then blow it out with an airline for a minute or two. Petrol is not miscible with water and the trapped petrol in the wall pores will stay trapped.

How would you avoid heating above the auto-ignition point?  I'm thinking maybe not a blowtorch?  I've been wondering how to do this safely for a while.

1 hour ago, J.C.MacSwell said:

Only if it was full/pressurized before starting the cut...

Full of water would be best - no fumes.  A kid died using a plasma torch on a recycled empty drum despite it being rinsed out.

Musk wants to use his boring company TBM for sewers.  Maybe rainwater/storm sewers could also work?  Might be a way to retrofit where no separate storm sewers exist.

Maybe look for visual programming for python?  Seems there are a bunch of options there.

OK.

Not sure exactly what the node is representing - a group of files that were pre-selected (or chosen) by hand?  So it would create a sort of meta-hierachy or graph for the filesystem?

Looks like you already found it, so is this promotion?

One problem with hydrogen is it is cheaper to strip carbon from methane than to do water electrolysis!   Not a problem (for profits) until there is a carbon tax.

I just read that a nuclear plant in California isn't renewing their license, not because there is a push against nuclear there, but because they can't make money.  Renewables are cheaper and there is a dip in demand between 9 and 5 which is bad for base-load power.  They could produce hydrogen in the lull, but I guess it's not profitable either, or maybe within the lifetime of the plant, renewables will start producing the hydrogen more cheaply - who knows.

Built in a mining pit, collects water too.  Not for deserts I guess.

Solar power tower - Wikipedia:  https://en.wikipedia.org/wiki/Solar_power_tower#Novel_applications

1 hour ago, ScienceNostalgia101 said:

So why aren't they being done more, then?

Sandstorms damage panels, no water to clean the panels, not close to where people live, generally.  Seems like these problems can be overcome, but the $ is probably not there (yet).

One artificial moonlit test city, maybe - it's not a great idea.

Solar panels in deserts can power the world.  Some projects already exist.

This might interest you: China May Soon Have a Second (Artificial) Moon:  https://www.space.com/42183-china-artificial-moon.html

Downside:  even from LEO, reflection is about 30 km wide (IIRC) because of Etendue - Wikipedia:  https://en.wikipedia.org/wiki/Etendue  which means to get 1:1 sunlight, the mirror would need to match that size!

Also, rain and clouds means no light.

There are also ideas about solar panels in space with energy beamed to earth using microwaves.

On 10/22/2018 at 2:26 AM, John Cuthber said:

If you can get a syphon that runs uphill then we have solved the problem (And most of the world's  other problems too)

So "pumped"?  Good point but a bit pedantic.

3 hours ago, ScienceNostalgia101 said:

The idea is more so that the water would be siphoned off to said reservoirs before it gets beyond that point.

I'm not sure why it would need to be an outright boat, though. If it were a simple concave-up structure, wouldn't buoyancy itself act as a restoring force toward equilibrium if it even so much as began to tilt to one side?

Also, don't desalinization plants continuously use electricity while desalinating  water? Wouldn't constructing a rain collector be an investment in the short run that pays off in the long run through savings on electricity? Or would water siphoning consume even more electricity?

Fine if it rains.  Need to keep the sides of the reservoir above sea waves, like by flotation.  I was told Australian pools by the ocean sometimes get sharks in them.  "Because in Australia, sometimes you have to pick a shark out of a pool" https://www.goodthingsguy.com/environment/australia-shark-pool/.  So the sides might need to be high enough to keep out marine life.

For the ocean rise part, it seems unlikely the mass of antarctic glaciers plus volume expansion caused by temperature increase would equal what is siphoned off and never returned to the ocean (somehow).  That would be a lot of very large reservoirs.

1 hour ago, Enthalpy said:

Planetary (epicyclic) gears are compact and powerful at small electric motors. Would they be good for electric aeroplanes?

Since planetary gears are used in turboprop engines and/or turbofan engines, I think yes.

Also, I've noticed a sort of upper limit to existing permanent magnet motors of ~400 Hz or so, is there an induction resonance or high power electronic switching limit, or in other words, what limits the top frequency of electric motors?

15 hours ago, Endy0816 said:

lol, there is actually.

Reality Hacker for the Android. Can apply various filters in real time.

https://play.google.com/store/apps/details?id=com.visor.visionhacker&hl=en_US

It was still pretty faint but could identify a wet area via Inverted Sorbel Edge. There's different options including color filters though.

Yeah, very close, maybe suggest a "painting" or "wet paint" filter to highlight subtle colour differences, might help to turn on the flashlight too.

Extrasensory colour perception - might be an app for that, one that exaggerates the colour differences it sees the same way an app can be used as a magnifying glass.  Depends on the camera sensor's colour sensitivity.  Filters might prove handy because of the limited colours actually perceived by camera sensors (red, green and blue), same as our eyes.  When it comes to paint though, different light will interact with the paint reflection spectra(?) which may in fact include colour wavelengths we interpolate.  This isn't as likely a problem in the given case where we want to discern between wet and dry or between new and old.

1 hour ago, John Harmonic said:

I am guessing if it did work then people would be using it by now. I am sure scientists and engineers would wonder about such a powerful thing "to transmit wireless power" and look further into in theory. I love Nikola Tesla and he did a lot for the world with AC but he is only a man... man can be flawed.

Not necessarily, if no practical application exists given the inroads made into other means or, if power is in the atmosphere, how do you charge(ha) people for use?

Still not clear why it's "no".  It seems to me what Tesla describes is similar to a fluorescent tube, or similar, where current flows through an ionized gas, not transmitted by electromagnetic energy (like wireless phones or toothbrushes).

Here's another article,  seems like we need to build one to test out theories.  Ionized atmosphere VS EM waves.  Nikola Tesla On Wireless Energy Transmission:  http://teslaradio.com/pages/tesla.htm

3 hours ago, Strange said:

Depend what you mean by "work". My understanding is that it was originally designed as a radio transmitter. It would have worked for that. Unfortunately he decided to try and implement his crackpot "wireless power" ideas halfway through construction and so the project was abandoned by his (sane) investors.

What exactly makes "wireless power" crackpot?  Also, the radio transmitter would not be based on EM waves, but on ionized atmosphere - does that actually work?  Tesla planned on modulating at ~11 Hz, really low for a radio signal.

I think (new to this too) that the concept below is the intent - to (super)charge or ionize the atmosphere?

How Powering with Atmospheric Electricity Works - YouTube: 

Hydrogen powered, fuel cell electric aircraft company: Electric Air Taxi – HY4:  http://hy4.org/sample-page

Thanks!  For short hops flights, maybe consider compressed hydrogen instead, still higher volumetric energy density than Li-ion batteries and much lighter.  Then there's Skylon for LH2 powered spaceflight - Skylon (spacecraft) - Wikipedia:  https://en.wikipedia.org/wiki/Skylon_(spacecraft)  Hydrogen Turbojet engines are being developed.

How would burning hydrogen in an ICE or turboprop compare?   More noise, but efficiency?

Also, SOFC output is so hot, it is used to run a turbine to increase efficiency in generator situations.  Could some version of this work to combine electric and thermal power?

DC to AC is called an inverter and they are a fairly common item - price varies with Watts delivered.  Don't think it will run very long though unless you have large batteries available.

Where does polonium come from and how much energy is needed to extract it?