Today I Learned

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Today I learned that one molecule, in an E. coli cell (biology's standard bacteria), is at a concentration (in the volume of the cell) of 1.6 nanomolar.
 
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Hornbein said:
I believe I read that Alan Turing invented that.
Yes, or at least he had a hand in it - from the wiki entry I linked:

A prototype was developed at Bell Telephone Laboratories, under the direction of A. B. Clark, assisted by British mathematician Alan Turing,[1][2] and demonstrated to the US Army. The Army was impressed and awarded Bell Labs a contract for two systems in 1942. SIGSALY went into service in 1943 and remained in service until 1946.
 
RIL about two vs three-leg SCR control in three-phase resistive circuits.

Turns out two legs are often better than three. Three-leg control produces about 50% more heat and generates harmonics.

On the down side, you have to consider the maintenance people. When you kill power to the controller, you still have a hot leg. So you have compensate for that in some fashion or someone could get killed.
 
Industrial 'Best Practice' (and in all Safety codes I've seen) is ALL electrical supply conductors have a Manual, Physical disconnect that is Lockable in the Off position. Betting a life on a semiconductor is not allowed.

Similiarily, All 'Emergency Stop' buttons on machinery must physically interrupt the supply and must require physical action to re-energize.

Any personnel that don't use them are getting close to "Darwinism in action."

[end rant]
 
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Tom.G said:
Industrial 'Best Practice' (and in all Safety codes I've seen) is ALL electrical supply conductors have a Manual, Physical disconnect that is Lockable in the Off position. Betting a life on a semiconductor is not allowed.
Yes. But experience demands that one accounts for this. People have gotten hurt before because of this. That's why that particular discussion came up.
 
...and it is a pain. I'm not sure how we're going to do this yet. If it acts quickly on the third leg we are back to producing a lot of noise. But I'm sure there's a standard solution. It came up in a 6 hour meeting today :H and I haven't talked to our panel designer yet.
 
TIL that Teutonic values are not what I thought they were. According to this week‘s Economist, Germany has more yoga instructors than coal miners.
 
fresh_42 said:
Interesting idea: Couldn't we harvest all the energy wasted in gyms all over the planet?
I've looked at that. Humans are very poor producers [we don't produce much net energy] so the ROI isn't there with traditional technology. But with nano technology or some other up and coming exotic technology, maybe it would eventually be doable.

Humans can produce 100 watts all day long. At 300 watts we are down to something like an hour for the average adult. An Olympic athlete can produce 1000 watts for a few seconds up to a minute or so depending on how it's done.

Someone was once experimenting with sidewalks that produce power. But I'm sure they found the same problem.
 
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Consider for example the Gossamer Albatross
1632589156317.png


"In still air, the required power was on the order of 300 W (0.40 hp), though even mild turbulence made this figure rise rapidly.[2] "
https://en.wikipedia.org/wiki/MacCready_Gossamer_Albatross

But it nearly killed the guy who crossed the English Channel, who was in peak physical condition.
 
I was playing with the idea of a shaker charger for your mobile. So I bought a shaker flashlight to see how much power it produces. I found a little battery inside that powered the LED light for a very long time - several days IIRC. When that ran out the LED went off. But my oscilloscope showed that the voltage from the shaking never even exceeded for the forward bias voltage need for the diodes to conduct. So it couldn't possibly charge the battery.

When I did the calculations for a magnet for my shaker charger, I found the magnet would have to be so strong that it would wipe out your credit cards and possibly be dangerous.
 
Ivan Seeking said:
Humans can produce 100 watts all day long. At 300 watts we are down to something like an hour for the average adult. An Olympic athlete can produce 1000 watts for a few seconds up to a minute or so depending on how it's done.
Tell this a professional bicyclist climbing a pass at 3,000 m!

Anyway. The basic concept in gyms is gravity and resistance. We could use gravity to pump water and resistance for generating eddy currents (if the bicycles and steppers at gyms don't do this anyway). Net energy doesn't count because we will not have to pay for the input aka food.
 
fresh_42 said:
Tell this a professional bicyclist climbing a pass at 3,000 m!

Anyway. The basic concept in gyms is gravity and resistance. We could use gravity to pump water and resistance for generating eddy currents (if the bicycles and steppers at gyms don't do this anyway). Net energy doesn't count because we will not have to pay for the input aka food.
The guy flying the Gossamer was a professional and he could barely maintain 400 watts. What's more. I did a project where I had to quantify these numbers for a public use device that included professionals.

I found that the cost of the hardware and implementation exceeds the return on investment.

When I said net energy, I was referring to the energy after losses, not food.

And you know as well as anyone that citing meters without time is meaningless. In principle a snail could climb mount Everest. That doesn't mean it would be producing useful energy.
 
A bicycle page says 540W at the final slope, which normally lasts about 10 to 20 minutes.
https://www.tour-magazin.de/profisp...verstehen-wattleistungen-im-check/a44719.html

My idea was to create the new tools which are installed anyway with the new techniques. E.g. I have manually pumped water. It works. I have no idea what the yield is, but the losses can be neglected. Same as we neglect produced heat nowadays. If two dozen people a day pump water instead of only lifting weights, we should have positive net energy. Same with the bicycles and steppers which could produce currents.
 
Ivan Seeking said:
RIL about two vs three-leg SCR control in three-phase resistive circuits.

Turns out two legs are often better than three. Three-leg control produces about 50% more heat and generates harmonics.

On the down side, you have to consider the maintenance people. When you kill power to the controller, you still have a hot leg. So you have compensate for that in some fashion or someone could get killed.

Just a wild idea here: How about the equivalent of a GFI? (All line currents must balance to within X milliamps) I haven't looked to see if there are any made for 3-phase.

It still may not meet all the code requirements though.
 
Pumping water in a gym requires a lot of new hardware. It's already mechanical motion and can be connected to a generator. It's just not enough to matter.

Even if everyone would produce 100 W for an hour every week we only get an average power of 5 GW globally, or ~0.2% of our electricity consumption. And we would need a lot of additional hardware in millions of places for that.
 
Ivan Seeking said:
In principle a snail could climb mount Everest. That doesn't mean it would be producing useful energy.
This is offensive to molluscs. They are differently abled.
 
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TIL The James Webb launch date is now December 18th this year.
 
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DaveC426913 said:
TIL a new word: immanent. (I had to look it up, thinking maybe @fresh_42 made a mistake.)

https://www.physicsforums.com/threa...an-intuitive-explanation.1007568/post-6546846
I thought I should look it up, too, but it is so Latin that I thought it works in English, too, not only in German. I learned something similar yesterday. @Dale used the word desiderata. I didn't look it up since it was pretty obvious what it means. I just thought: interesting, English native speakers also use Latin words to pimp their statements!
 
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fresh_42 said:
English native speakers also use Latin words to pimp their statements!
The “pimp their statements” is hilarious. And true, I was absolutely doing that.

"We don’t just borrow words; on occasion, English has pursued other languages down alleyways to beat them unconscious and rifle their pockets for new vocabulary."
--James D. Nicoll
 
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fresh_42 said:
@Dale used the word desiderata. I didn't look it up since it was pretty obvious what it means.
Yep caught that. And I did look it up, even though the context made it obvious.
 
jack action said:
How cute that Youtube thinks of itself as a reliable source of information.
Over the past couple years I have had a few guys working in my house (plumbers, electricians, and more). I have seen them "u-toobing" how to do some of the work. If my clients caught me doing that I'd be fired.
 

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