Slashdot is powered by your submissions, so send in your scoop


Forgot your password?

Slashdot videos: Now with more Slashdot!

  • View

  • Discuss

  • Share

We've improved Slashdot's video section; now you can view our video interviews, product close-ups and site visits with all the usual Slashdot options to comment, share, etc. No more walled garden! It's a work in progress -- we hope you'll check it out (Learn more about the recent updates).


Comment: Re:Probably best (Score 1) 312

by hey! (#49515823) Attached to: Automakers To Gearheads: Stop Repairing Cars

Cars from the 60's-70's suck big time.

Sooo true. My first car was a 1976 Buick Century with 231 cc V6 engine, normally aspirated. The engine wasn't half-bad -- this was before emissions controls other than a PCV, EGR and catalytic converters so it *was* simple to work on -- but in every other respect it was dreadful by modern standards. 105 horsepower to move 3800+ pounds equals 0-60 in 17 seconds and 15 miles to the gallon, baby.

But aside from power to weight ratios, the thing which really sucked about old cars was the suspension and handling. Every time I see a car chase in a movie from the 1970s I laugh because I *remember* driving cars like that. By modern standards they cornered like inebriated hippos on roller skates.

Comment: Re:My B.S. Detector is Going Off (Score 1) 66

by Bruce Perens (#49515639) Attached to: Old Marconi Patent Inspires Tiny New Gigahertz Antenna

If the end of the coil that is hanging is grounded (earthed), it becomes an autotransformer. As it's shown, it's a variable inductor and the disconnected end is irrelevant and has no meaningful physical effect at the frequency a spark transmitter could have reached.

This comment seems to get closer to what they actually mean in their scientific paper. But the article about it is garble and the paper might suffer from second-language issues, and a lack of familiarity with the terms used in RF engineering.

Comment: Re:Hmm, I guess I invented this as well... (Score 1) 66

by Bruce Perens (#49513567) Attached to: Old Marconi Patent Inspires Tiny New Gigahertz Antenna

Damn, I wish I would have patented that and all its quantum magic...

I noticed that my vertical transmitting antenna often works better if I connect a horizontal wire about the same length as the antenna to ground at its base! The wire isn't connected to the transmitting side of the circuit at all! And how well it works varies depending on the length! Obviously there is some deus ex machina at work here...

Comment: Re:My B.S. Detector is Going Off (Score 1) 66

by Bruce Perens (#49513517) Attached to: Old Marconi Patent Inspires Tiny New Gigahertz Antenna

Clearly you missed the bit where they invoked quantum mechanics, surely that explains away all the inaccuracies, like the fact you can already buy chip scale dielectric antennas

The thing that I really hate about Innovation Stories is that the reporter invariably doesn't understand what's going on, and invariably is easily convinced that The Obviiously Very Technical People have some very valuable invention.

Comment: Re:Why on the ISS? (Score 1) 159

by camperdave (#49511895) Attached to: ISS Could Be Fitted With Lasers To Shoot Down Space Junk
For the love of sanity why? The moon is 770 times as far away, which means you'd need a laser almost 600,000 times more powerful than one in Low Earth Orbit to deliver the same "punch". (Lasers spread out like any other beam of light, so inverse square law applies). Your aiming mechanism also needs to be magnitudes more accurate. If you're running this off solar power, then the moon based laser is going to be out of commission half the time, and is not going to be at peak energy most of the time. Furthermore, the launch costs are going to be astronomical.

A satellite based system can be in perpetual sunlight, with the solar panels constantly at the optimum angle for energy collection. You're right on top of the target, so aiming is easier and power delivered on target is greater.

Comment: Re:Environmentalism, much? (Score 1) 116

by hey! (#49511715) Attached to: Pull-Top Can Tabs, At 50, Reach Historic Archaeological Status

By that argument why bother excavating garbage pits, when temples and mausoleums are so much sexier? Well, because temples and mausoleums are consciously built by high status people to convey messages. Garbage (and by extension pollution) tell you things about everyone, including things they didn't think worthy of documenting but turn out to be interesting.

Comment: Re:And Microsoft 'saved' Apple... (Score 1) 106

It's news because it wasn't known before and it tells us a lot about Google that we've only had hints on before. It's also an interesting recap on the early days of Tesla. Tesla wouldn't be the first company that released (despite their best efforts, I'm not blaming them) overpriced underspec'd crap at the beginning that could have severely dented their future business, but it's often hard to remember that.

Remember the original iPhone? EDGE only? Required special SIM cards? Barely supported text messaging, and didn't support MMS messages at all? Didn't run third party apps at all? You don't? Nobody does? It's true!

Yet the iPhone survived all that and nobody remembers how awful the first version was. Turns out Tesla's original sedans were a similar story. I didn't know that. I thought they were always cutting edge.

Comment: Re:For the Conservation Crowd (Score 1) 579

by hey! (#49511535) Attached to: William Shatner Proposes $30 Billion Water Pipeline To California

Spoken like someone with absolutely no engineering experience. Engineering as a discipline has this impish habit delivering things most people never imagined possible. This misleads them into thinking that engineering can give them anything they can imagine, particularly if the concept seems simple to them.

Take the suggestion elsewhere in this discussion that water be piped from the Great Lakes to California. Nothing could be simpler in conception -- a 2000 mile long pipe. We've built oil pipelines longer than that. The longest crude oil pipeline in the world is the 2500 mile Druzhba pipeline from Russia to Germany, so a 2000 mile long water pipe should be a cinch, right?

Here we get to the place where engineering starts being a bitch. You see, it's one thing to imagine a cost-is-no-object project, but the truth is cost is the single most important limitation on water use. It does no good to supply water to California almond farmers if they have to sell their almonds at the same price/weight as gold to pay for it. We use a *lot* more water than oil, and we expect it to be way, way cheaper. The current spot price for crude oil is about $57 per barrel -- roughly $1.36/gallon. Agricultural users in California pay something like 3/10 of a penny a gallon -- roughly speaking they expect water to be about 500x cheaper per gallon than oil. If pumping adds a penny to the price per gallon to the price of crude oil, that's no big deal, less than 1%. Add a penny per gallon to the price of water and you've quadrupled your farmer's water cost.

A system that delivers water can be expensive to build, but it has to operate cheaply and reliably. That's why water systems engineers avoid pumps and rely on gravity to do most of the work of moving water. The longest water supply pipeline I know of is the Goldfields Water Supply Scheme, which transports water 330 miles with the aid of 20 pump stations. The economic justification for this project? To support gold mining. To give you an idea of how much expense was tolerated when the Goldfields system was built, it replaced a system where water was packed in by camel train. Today users there pay 7x as much per gallon as users in California do for water. Assuming the CA system could be operated for the same price, you could actually dispense with actually building the system. Raising the water price from $0.003 to $0.02 would reduce water consumption in California to sustainable rates -- even under drought conditions. It'd do so by causing agriculture to move out of state. Probably some population too.

365 Days of drinking Lo-Cal beer. = 1 Lite-year