Follow Slashdot stories on Twitter

 



Forgot your password?
typodupeerror

Comment: Re:Bullshit (Score 1) 210

by RockDoctor (#48900827) Attached to: At Oxford, a Battery That's Lasted 175 Years -- So Far

It's just that there's very little practical applications for such very low currents.

The Wikipedia article on Zamboni piles cites image intensifier tubes as being a past application. back in the days when you used photomultiplier tubes to amplify the electrons from each re-focussing of the image. Low current, high voltage.

Comment: Re:Bullshit (Score 1) 210

by RockDoctor (#48900809) Attached to: At Oxford, a Battery That's Lasted 175 Years -- So Far
Voltage per pair of discs is around 0.8V for silver-MnO2. So to get 2kV, you'd need around 2500 disc pairs.

I have a War Department Geiger counter that I'm trying to get back into commission ; it needs a 120V DC power supply that fits into a 5 x 5 x 10cm cavity. The original achieved this by stacking together 100-odd 1.5V Leclanche cells into a carrier. But they stopped being manufactured around 1971.

I'm going to have to be creative.

Comment: Re:Crash-testing & strength? (Score 1) 128

Summary says car bodies, so these are essentially kit cars.

As such they'd be registered here on a "Q" plate and be subject to additional checks during the annual mandatory Ministry Of Transport inspection. Because the design is a one-off, then there is no "type" which could have been approved, so before receiving a registration mark that would allow it to be driven on the public highway (and incidentally, to be taxed), it would need to be inspected by a government-approved inspector to determine if it is safe to e on the road. They look at things like brakes, body strength, engine emissions, lights and indicators to other road users. But they don't look at dynamic stability at 80 in a gusty cross-wind.

It wouldn't be too difficult to get this sort of vehicle registered as a "one off", but it would be a hassle. A common scheme people use is to register the vehicle as a "showman's vehicle," which implies the non-standard construction, lack of a "type" and unusual shapes. It also implies that every MOT inspection will be a detailed one. A hassle, but do-able : I have a friend from university days who used to live in and drive around in a bus, which he'd turned into a mobile home with a 10ft open-air verandah on the back. That was a "showman's vehicle". Currently he uses another home-made mobile home on a chassis and engine from a Ukrainian-built ICBM launcher ; "showman's vehicle" again. Do-able, but a hassle.

Comment: You can "post" things on Google+ ??? (Score 1) 209

by RockDoctor (#48900573) Attached to: Tracking Down How Many (Or How Few) People Actively Use Google+
This "plus" thing - it's some sort of advertising annoyance that Google websites shove in your face from time to time? but I don't understand what this thing about "posting" on it is, and even less so why I'd want to do whatever that is. I'm not even sure how (or why) I'd go about finding out if someone were on Google+ to read my post. It's all terribly amorphous.

Comment: Re:This has been know for a while... (Score 1) 121

If the worst you can think of is being Goatse-d, then you do need to get out more. Or speak to someone who is allowed out without supervision by a particularly repressed adult.

(Incidentally, goatse.cx is a perfectly respectable mail service these days. I use it for my online courses.)

Comment: Re:New System: Kuiper Planets (Score 1) 170

There is a general dispute in taxonomy between "lumpers" and splitters" - people who say "this, this and this share these characteristics, and so I lump them together in one taxon" versus those who say "this, this and this differ in these characteristics, and so I split them into these taxa".

You're evidently a splitter. No disrespect about that - it's a defensible position (see above). But being a lumper is also a defensible position (see above).

The important things that you need for designing a taxonomy are to know what questions you want your taxonomy to address - if you're wanting answers to questions of surface gravity, then a taxonomy based on colour is unlikely to be helpful, for example.

Our current taxonomy for planets is based on the observational status of the planets in respect of their neighbours - the "cleared orbital region" criterion. In principle, that is an addressable question - observe the skies, plot the orbiting bodies down to a few percent of the size of the planets of interest, question answered.

Where things are getting confused is that many people project questions of the origin of the planets onto the orbital classification. Which may not be the most logical thing to do, when looked at in the context above. The two questions are not strictly related : Earth, Venus, Uranus and Pluto all appear to have suffered a giant impact in the late stage of their construction, but Pluto does not currently have a cleared orbit to make it a "planet" under the orbital classification. So our believed-to-be-correct models of origin processes do not (necessarily) align with current orbital status. But you can see from the length of my qualifications above that one taxonomy split is based on fairly long chains of cause and implication, and the other on simple Newtonian mechanics. So I can understand why the IAU decided to go with the relatively simple present-day orbital status criterion.

If I were to design a planet taxonomy, I'd use a criterion of sphericity (is the shape within X% of being a simple spheroid) to divide planets from "minor planets" (you can look at it as the interplay of material strength versus object mass, if you like), and at the upper boundary the presence of fusion (separating planets from stars, with a fudge area to deal with brown dwarfs). But that criterion shows my interest in body materials (I'm a geologist by trade), which differs from the interests of astronomers in general.

Comment: Re:time to buy futures, now. (Score 1) 441

by RockDoctor (#48842239) Attached to: Why We Have To Kiss Off Big Carbon Now

Just until the Saudis decide they've screwed the Iranians enough and cut their production again.

Iran isn't the target. They're in the same game as the Saudis.

The aim of this slump is to bankrupt the fracking industry. Once that has been done, production will be throttled back to bring the prices back up, but not to levels that would allow fracking to resume.

Comment: Re:"cut and paste"? (Score 1) 174

by RockDoctor (#48825105) Attached to: Authors Alarmed As Oxford Junior Dictionary Drops Nature Words

but today nobody does that any more.

Not true.

Some times it really is quicker to do the job in an analogue way than to figure out a way to do it electronically with what tools are available. Or, which tools are allowable according to a site's IT policies ; if I'm forbidden to use "portable" apps by the IT department on a particular job, then it doesn't matter if I've got an appropriate DTP or CAD or drawing application on a memory stick. Those sites are also likely to be the ones that take 3 weeks to process an application to have an application installed.

Cut, paste, and dot over the edges with correcting fluid still works just as well, and can be effective. A couple of tips : if you have the opportunity, do your compositing at double-size if you can, then in the final copy down to correct scale your errors will halve ; if you have reasonably heavy paper, tearing rather than cutting will produce a more feathered edge that shows up less.

Comment: Re:This makes sense nomatter your politik (Score 1) 202

by RockDoctor (#48823399) Attached to: Obama Planning New Rules For Oil and Gas Industry's Methane Emissions

trust me here, methane aint nothin to fuck with. tightening up leaks is inarguably a good thing.

This is true for far more direct reasons than greenhouse gas considerations (valid though those concerns are). Methane is a readily flammable gas. The oil industry has been paying most of my pay check for thirty-ish years for gas detection and analysis both for exploration reasons ("what have we got down there?") and safety reasons, in more or less equal measure.

The fact that you can sell it too is another, non-trivial incentive to keeping your wells, well heads pipeline etc in good condition.

There shouldn't be a need for regulation in this area : industry best practice and existing regulations about worker safety (there are laws against killing your workers) and environmental safety (there are laws against killing your neighbours and passers-by) ought to be sufficient. I smell politicians in "the public are looking, look busy!" mode.

Comment: Just name him, why don'tcha? (Score 1) 202

by RockDoctor (#48823293) Attached to: Obama Planning New Rules For Oil and Gas Industry's Methane Emissions

according to the person, who spoke on the condition of anonymity because the administration had asked the person not to speak about the plan.

The number of people so instructed is unlikely to be in the thousands ; probably only in the dozens. So by releasing this information in this way, they've come very close to pointing the finger of suspicion directly at him (or her).

Way to protect your sources, guys. I hop that you get lots more people bringing you scoops. Not.

Comment: Quern. Or (flint) knapping. Or gas lights. (Score 1) 790

by RockDoctor (#48798679) Attached to: Ask Slashdot: Sounds We Don't Hear Any More?

More points for the longer they lasted (typewriters were around for over a century).

A quern is a hand-powered grindstone. Practically every house in the world - well, the world grinding grain to make bread or porrage/ pottage/ gruel - used one from the dawn of seed gathering (centuries to millennia before the dawn of agriculture) until about the start of the industrial revolution. Say, between 10 and 20 thousand years.

They only went out of use when it really became cheaper and easier to take your grain to the mill to get it ground by wind/ water/ horse power instead of indulging in (literally) "the daily grind".

If you want a million or two years more of duration, then you could go for the sound of stone on stone, making a new stone tool. More latterly, depending on region, antler on stone, but that's probably only a few tens of thousands of years.

Oh, you wnat something technological?

How about the "pop" of a gas light lighting within it's mantle? These days you probably won't even hear it on a camp site - just the click of an LED switching on/off - but for a century or so it represented the chemical industry, the first large-scale "to the door" distribution network (home many optical fibres still run in trenches originally cut for gas pipes?) ; the billing that went with it, needing computers (human ones, then adding machines, then typewriters).

Nothing succeeds like the appearance of success. -- Christopher Lascl

Working...