Follow Slashdot stories on Twitter


Forgot your password?
Slashdot Deals: Deal of the Day - 6 month subscription of Pandora One at 46% off. ×

Comment Glue foam guns. (Score 1) 712

They shoot non-toxic foam that expands, and is sticky, then hardens into soft and rubbery in 10-20 seconds.
Cop shoots perp who soon is covered, sticky and cumbersome as the foam builds up. If he fell over = stuck to the ground.

He might overheat, since foam is an insulator. It would be soft enough to manually remove from mouth/nose.

Biggest problem would be the mass a cop would have to carry. At 1 pound per cubic foor he could easily carry 20 pounds, plus the 10 pound ejector.

A car could carry lots = good crowd control weapon.

clean up = a problem.

Comment Bag Lady Effect (Global) - BLEGS (Score 1) 563

If stuff was free, we would all turn into BLEGs Everything hoarders get they gather for free and the fill their space, be it house or box world on the street.
If stuff is free to start, it must then have a cost to keep or the BLEG effect will rule.

If stuff cost $$ to keep, the richest piles would belong to the richest people, Larry Ellison would have an island covered with stuff - OH, he has that now?

Comment Re:Bacteria spread via the air (Score 1) 118

Yes, it depends on the anti-corrosion additives that are in the water. The proper ones block copper oxidation. Back when I was a young engineer, we had a boiler system that was protected this way, and we took samples evry month and sent them off to the boiler chemical company, who then sent us a list of actions to rebuild the additive prifile.

I expect external cooling towers are much the same, as this search reveals.
Just text to schedule, add the chemicals and all is well.

Comment Re:Bacteria spread via the air (Score 1) 118

Proper antibacterial design, with maintenance, never provides a growth medium for whatever bacteria the winds bring in = no films in the first place. Sadly, human nature and bad maintenance = eventual fail mode = biofilms and mats can form that constantly shed bacteria into the air flow.

Comment Re:Yeah, I thought this problem was solved (Score 4, Insightful) 118

But, we forgot about lazy, cheap people.
Yes, chlorine or hydrogen peroxidation would solve this, but require some method to maintain the antiseptic aspect.
Copper sheeting might shed enough Cu ions for many years, but would ne replacing as it eroded away.

Newly installed cooling towers deal with this, as this search shows.

Comment Capacitor faults and strengths (Score 1) 147

1 Capacitors hold charge between two plates separated by the electrolyte, and typically excess electrons accumulate on one conducting plate as a cloud. Once you reach a certain voltage, the insulation fails = punch-through. If self healing, the voltage will fall and the arc will stop before the charge is gone. If not, most of the charge will dissipate.

2 Capacitors are the mechanical analog of the spring, more force = more spring stretches, in the same way as you charge a capacitor the voltage increases as the charge increases. There is not voltage plateau of the the electro-chemical difference. Charge Q = 1/2 C * V * V, with Q = coulombs C = farads, and V = voltage. Not the square function, when voltage drops by half, charge is 75% gone, and vice versa. The voltage falls, so there needs to be a regulator for loads that need a constant voltage.

3. Since all surfaces are in parallel, charge and discharge can be very rapid, limited by path resistance and inductance.

4 Batteries change the chemical state of the charge/discharge compound, as a bulk material. This is inherently 25-100 times as much as a capacitor's charge.
Even these capacitors face these limits.

That said, their speed and near infinite life will find them a role, just where they will fit? My fitbit runs for a week on a capacitor and charges very rapidly. Will an iPad or android pone run on that sort of a tiny charge? It is possible that e-ink devices as book reading displays will get to do this, but devices that transmit RF power use more than 1000 times the power of an e-ink reader in static mode, and 100 time in rewrite mode

In practice, failures in system development, like unemployment in Russia, happens a lot despite official propaganda to the contrary. -- Paul Licker