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Comment A field full of two layers of firefighters. (Score 1) 102

As mentioned previously, my mental model of semiconductors and the like is a fireman's water brigade, were either the majority of the line has buckets or empty hands.

It helps if, instead of a line, you think of a LOT them standing in a two-D array (like in the yard of the burning building, or a section of a parade that's stopped to do a little demo). It's really three-D, but we'll want to use up/down for something else in a bit...

For metallic electron conduction everybody has TWO buckets, one for each hand, and when a guy by the fire throws a buck of water on it (bucket and all) on the fire, a guy farther back immediately tosses him a bucket, the guy behind him essentially instantly throws HIM a bucket, andso on. Hands are effectively never empty.

For semiconductors, imagine two layers of these guys, the second standing on the firsts' shoulders or on a scaffold right above them, and about enough buckets for each of the guys on the ground to have two and the guys on the scaffold to have none. (There's actually many layers of scaffold, but the rest are so far up that it's hard to get a bucket to them, so they mostly just stand around.)

Usually nothing useful is happening. Everybody on the bottom layer has both hands full of buckets, and it's hard to hand a bucket up to the guys on the top.
  - Electron-hole pair creation: Somebody comes up with the energy to heave a bucket up to the guys on the upper layer, leaving a guy with one hand empty in the lower layer. (Maybe somebody (a photon, for instance) comes along with a lacrosse stick and whacks a bucket up to a guy in the top row - dying or becoming exhausted and much weaker from the effort.) Now you've got one guy with a free hand in the lower layer (a hole) and one bucket on the top layer (a free electron).
  - Electron conduction in a semiconductor is that bucket on the upper layer. The guys there can hand it around easily, or toss it along a diagonal until it would hit a guy - who catches it. They're all standing on accurately-spaced platforms so the bucket can go quite a way before somebody has to catch it. Suppose there's a slope to the yard, with the fire at the bottom. Then, if tossed too far, the bucket might pick up substantial speed and knock the guy who catches it out of place (electromigration), or fall down to the lower layer and knock another bucket out of somebody's hand and bounce, ending up with TWO buckets on the upper layer and an empty hand below (avalanche electron-hole creation).
  - Hole conduction is when you've got an empty hand on the bottom layer: Now it's easy for a guy with two buckets to hand a bucket to a guy with only one, exchanging a bucket for an empty hand. But now the guy whose hand had been empty has two buckets and nobody in the downhill/toward-fire direction to hand a bucket to, while the guy who handed it off has an empty hand and can grab a bucket from somebody farther uphill / closer to the water source - or beside him, or diagonally. So "empty-handedness" (a hole) can move around as a persistent entity while the individual buckets gradually work their way in the general direction of the fire, only making a bit of progress "when a hole comes by". Though the water makes progress toward the fire, the action is all where the holes are making progress away from the fire.
  - Electron-hole annihilation: Somebody has a bucket on the upper layer when a guy below him has an empty hand. So he drops the bucket. CLANG! Ouch! Now there's no "free bucket" on the upper layer, no free hand on the lower layer, and the energy of their separation went somewhere else (knocking the guy sideways so he bumps into his neighbor and generally making the guys vibrate, "creating a guy with a lacrosse stick who runs off to whack at buckets", etc.)
  - P-type doping: A guy in the bottom layer had a sore hand and only brought one bucket to the fire, thus having a free hand from the start. He can take a bucket when a neighbor pushes it at him (the hole moves away). But he'd like to hand it off and have his sore hand free again (so holes tend to stick around at his site). It's lots easier to "make a free hole" by convincing him to hold a bucket in his sore hand than by tossing a bucket up to the guys on the scaffold, but does take a little effort.
  - N-type doping: One of the guys on the upper level really likes to hold a bucket, so he brought one with him. The guy next to him can grab it from him, but if another comes along he'll try to hold on to it a bit until somebody shames him into letting go again or wrestles it from him. It's lots easier to get him to let you use his bucket for a while than to pull one up from the guys on the ground, but it does take a little effort.
  - Tunneling through a potential barrier: There's a ridge across the field. It's hard to hand buckets up to the guys on the ridge, so they don't flow across it very well (unless someone at the side of the field is pushing the buckets really hard...) Occasionally the guys on one side of the ridge hand a bucket through the legs of the guys standing on the ridge to the guys on the other side.
And so on. B-)

I'm keenly interested in finding more material to read up on the observed Hall effect measurements. Thanks again for your contribution to the discussion.

The wikipedia article on the hall effect has a section on the hall effect in semiconductors, but both it and the reference it uses start from treating the hole as a charge carrier with a fixed charge and a mobility different from a free electron, and just computes formulai from there.

If the hall effect on hole currents were fallout from the hall effect on the individual electron bucket-transfers, rather than the hole acting like a positive charge carrier in its own right, you'd think it would go the other way

Comment Re:Systemd "Spec" or RFC? (Score 1) 677

It's a source that nobody knowledgeable appears to have contradicted. Challenging the source is reasonable if the information is untested. If it isn't challenged (and I notice you didn't challenge it) then it gains plausibility.

P.S.: Your attack is an actual ad hominem attack, admittedly against a dubious character. But just because the source is unreliable doesn't mean the information is wrong. And it was presented to a vocal audience with many knowledgeable individuals in it. So I tend to think that systemd does provide root services to users without rights to use those services. And this does sound like a dangerous weakness.

Comment Another useful vacuum tube: Thermionic converter. (Score 1) 102

Another vacuum tube technology with current applications and substantial advantages over semiconductor approaches to the same problems is the Thermionic Converter. This is a vacuum-tube technology heat engine that turns temperature differences into electric power - by boiling electrons off a hot electrode and collecting them, at a somewhat more negative voltage (like 0.5 to 1 volt), at a cooler electrode.

Semiconductor approaches such as the Peltier Cell tend to be limited in operating temperature due to the materials involved, and lose a major fraction of the available power to non-power-producing heat conduction from the hot to the cold side of the device. Thermionic converters, by contrast are vacuum devices, and inherently insulating (with the heat conducted almost entirely by the working electrons, where it is doing the generation, or parasitic infrared radiation, which can be reflected rater than absorbed at the cold side.) They work very well at temperatures of a couple thousand degrees, a good match to combustion, point-focused solar, and nuclear thermal sources.

Thermionic converters have been the subject to recent improvements, such as graphine electrodes. The power density limitation of space charge has been solved, by using a "control grid" to encourage to charge to move along from the emitter to the collector and magnetic fields to guide it (so it doesn't discharge the control grid and waste the power used to charge it).

Current thermionic technology can convert better than 30% of the available thermal energy to electrical power and achieves power densities in the ballpark of a kilowatt per 100 square cm (i.e. a disk about 4 1/2 inches in diameter). That's a reasonably respectable carnot engine. This makes it very useful for things like topping cycles in steam plants: You run it with the flame against the hot side so it is at the combustion temperature, and the "cold" side at the temperature of the superheated steam for your steam cycle. Rather than wasting the energy of that temperature drop (as you would with a pure steam cycle) you collect about a third of it as electricity.

It also beats the efficiency of currently available solar cell technology (and the 33.4% Shockleyâ"Queisser theoretical limit for single-junction cells), if you don't mind mounting it on a sun-tracker. Not only that, but you can capture the "waste heat" at a useful temperature without substantial impairment to the electrical generation or heat collection, and thus use the same surface area for both generation and solar heating. (Doing this with semiconductor solar cells doesn't work well, because they become far less efficient when running a couple tens of degrees above room temparature.)

Comment Re:It depends on somebody doing the actual work (Score 1) 677

The problem is, for years now, we have been assured that Open Source was the cure for problems. Just notify someone, and wait, and your problem will be fixed. I had it happen so many times in the old days. Now, developers apparently have stopped caring about this and care only about developing products for themselves. Sad, but what are you going to do? The concepts that made Open Source a big hit are being abandoned. Open Source isn't going away but it is definitely becoming less popular. Good news for commercial software companies that listen to their customers.

Comment Re:often ahead in the wrong direction, certainly d (Score 4, Interesting) 442

In some ways certainly they are "ahead" - California isn't shy about trying out new new things, or to put it another way "imposing more and more mandates on its citizens without any way of knowing how it will work out". Sometimes it works out well, sometimes it blows up in their face.

Oh, please. You could be in Kentucky or West Virginia, where the Koch brothers are experimenting with the laws.

Overall, we can see what all the experimentation in California, the willingness to jump off ledges no-one has previously tested, has done to California's economy over the last 30 years. Some people -like- California despite the economic and other problems.

Yeah, I would hate to live somewhere where jobs are plentiful, where the government is running a surplus ... wait, what economic problems?

Comment Re:Again: Big Dumb Co (Score 1) 146

It might surprise you to know I've wanted to do the EXACT SAME THING -- start a company to make dead-simple appliances. I can't tell you how many 20-30 year old appliances from the 80s I've replaced in the last 2 decades, and the replacements are good for 5-10 years. I'd pay $1,000 for a washing machine TOMORROW if it had quality components (switches, motors, hinges, etc.), user-serviceable parts, and if it would last 50-100 years. No reason it couldn't. I don't care if it's a bit heavier and has thicker parts and is a bit less efficient, as long as it lasts. You know what's inefficient? BUYING NEW DAMN APPLIANCES EVERY 8 YEARS.

Comment Easy answer (Score 2) 442

"What are you doing to make selling electric cars as profitable and painless for your dealers as selling gasoline or diesel vehicles?"

What am I doing? That's easy: I'm NOT GIVING A SHIT HOW THEY FEEL. If I want to buy one, I'll walk into a dealer, and they can take my money, or not. Salesman's not making enough money? Wah wah wah, go get a real fucking job and do something USEFUL for a living.

Comment Re:Much todo about zip--ConsoleKit2 is also suppor (Score 1) 677

FWIW, I have not seen any advantages to systemd, and I have not heard of any advantages that I would personally find advantageous. And there do seem to be potential problems.

E,g, faster boot times don't impress me at all. I'd be more impressed by longer up times. I find binary logs dubious, and many people have reported problems with them. Etc.

I have not personally had any actual problems with systemd, but it's not clear how I'd resolve them were they to occur.

So I'm both dubious about the advantages and worried about possible disadvantages. Sufficiently so that if a BSD supported the ext4 file system I would have a test installation running. But not yet sufficiently to reformat my file systems.

The trouble with a lot of self-made men is that they worship their creator.