Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!

 



Forgot your password?
typodupeerror

Comment I thought this was already solved. (Score 3, Interesting) 51

I was under the impression that the issue of translating LED light into a broad swath of color was an already solved problem (except for some fine-tuning optimization), using appropriately-sized nanoparticles which hand the energy from the photons around, slicing-and-recombining energy from photons into different sized packets and re-emitting the light at a frequency characteristic of the size of the nanoparticle. Cover the LED with a bunch of these in a range of sizes and you get a smooth spectrum.

Works the other way, too: Coat a solar cell with such particles and they take the random-frequency photons from the sun and slice them up into multiple new photons at a frequency good for the solar cell bandgap, and mash the levtovers into more big photons to re-slice to the correct size. (It's not 100%, since some of the photons get away. But it's more than a 2x improvement over a bare cell, which only takes one slice off each photon and throws the rest away.)

If this is correct, this project looks like just a fine-tuning of making the nanoparticles, or finding materials for them that are somewhat more efficient than what was already being used (which was pretty good).

I haven't been following this all THAT closely. Have I misunderstood the current stuff? Or is this just a little incremental tweak along the cutting edge?

Comment India (Score 1) 273

Mother Theresa would no doubt have printed a medical tool for removing IUDs.

Which would have been totally useless since most of the countries and places she setup shop didn't have access to birth control to begin with.

India, with its huge population, had a large program making IUDs available at no cost to people in the poorer regions who wanted them.

Mother Theresa's work included providing medical treatment to the poor in many of these same regions. Her clinics were noted for removing the government-provided IUDs of women who were there for other procedures, without seeking permission or even informing the woman that it had been done.

Comment Re:Feeding an island is DEADLY. (Score 1) 124

I've never seen "licensed" grid tie systems that didn't do what you describe.

And you won't: They can't be "licenced" if they don't do this.

About the only way you can feed the grid legitimately without such a device is by pushing on an induction motor (as happens sometimes in normal applications, like with a mo-gen system for an electric elevator when the elevator is being slowed down.) Induction motors depend on the grid for excitation and won't self-generate unless you've got enough capacitors hung across them (and your load) to make the net power factor capacitive. (This is unlikely but can happen in islanding, so you generally aren't allowed to hang a prime mover, like a water wheel or windmill blade, on an induction motor, and hook it to the grid, without adding such controllers. Generation from induction motors in an outage should only last for a few seconds while they suck the inertia out of some spinning mass and run down.)

Last I looked it cost about $2,000 extra to have a grid tie inverter with sell-back (and high-current load direct-connect with inverter "helping"), compared to an equivalent inverter from the same manufacturer that only fed the load with inverter output but could charge the batteries / feed the inverter with rectified line power when the grid was up.

In this case the $2k-ish bought you an extra box containing:
  - a contactor (to jumper the line to the inverter output) and
  - a circuit board that controlled the contactor and acted as a peripheral to the brain of the inverter, providing it with phase measurements (to line-up the inverter phase with the line phase before closing the contactor) and a voltage and frequency measurements (to tell the brain when the grid was failing, so it could open the contactor and cut you loose).

Though this was an add-on box, other products with the function built in also brought a similar premium compared to non-sell equivalents from the same manufacturer.

Straight grid-tie devices feed the harvested power to the grid and depend on it for interconnect and timing reference. Yes they don't feed a dead grid - but that means they don't feed YOU when the grid is down, either.

I'm maybe three years out-of-date on this information so the market may have changed.

Comment Even more. (Score 1) 524

Even if only a third of the people stick around after din-din (and it's usually more), it's still the equivalent of getting more better than a 10% increase in manpower for the price of nine dinners (in bulk) per day per extra head - FAR less than the cost of hiring another head.

Did the math wrong: Make that about 17% more "heads" for the price of six dinners per night for one in three staying an extra half-shift..

Comment It pays MUCH more than that. (Score 1) 524

FWIW, most "free food" programs encourage workers to come in earlier (for breakfast) or stay later (work past dinner time) or to not spend a long time off the company property over lunch. The extra time at work usually pays for the food costs.

It pays MUCH more than that. A typical thing that happens at startups is the company buys dinner - and the bulk of the engineers chow down and stick around another four hours. Not only do they get half-again as much time, but they get it in a block. For a programmer or other design engineer that means they haven't "lost state" and are even more productive than if they'd just worked three days instead of two.

Even if only a third of the people stick around after din-din (and it's usually more), it's still the equivalent of getting more better than a 10% increase in manpower for the price of nine dinners (in bulk) per day per extra head - FAR less than the cost of hiring another head.

And then there's an adminstrative pathology: The new management comes in, sees how much is spent on the food (but not how much is gained as a result), decides that their predecessors were stupid and the employees were looting the company, and stops the food. So come dinner time the employees go out (or home) to dinner and don't come back. Immediately it's like they lost somewhere between 10% and 33% of their work force without any reduction in payroll costs. (That's not counting how disgruntled some of the employees become.)

I've been at three companies where this happened, and observed several more. All but one of 'em folded shortly thereafter - and the one that survived went through a near-bankruptcy that destroyed the original investors' equity and left it in the hands of the bondholders before it recovered.

Comment Feeding an island is DEADLY. (Score 5, Informative) 124

It could even keep a local part of the grid up while all others around them suffer power failures.

And that is a BIG no-no. Because it kills linemen trying to fix the outage.

Those transformers work both ways. Your little generator or inverter gets stepped up to maybe 8,000 or 12,000 volts. Then a lineman who thinks the power is down brushes against a wire (or comes within a quarter-inch of it) and is "burned" - to death.

Grid-connected inverters with a "sell" feature MUST monitor the network and shut down if they detect islanding - being cut off from the grid, with one or a collection of generators running autonomously. It's perfectly OK to feed power into the grid when it's up (if you're using UL approved equipment, connected according to code, inspected for compliance, and the utility knows you're doing it according to the rules.) It's perfectly OK to have things wired so your equipment still feed your house if the grid goes down, but it MUST cut itself off from the dying or dead grid and stay off until the grid comes back up and stabilizes at the nominal voltage and frequency.

Comment Classic hovercraft disaster ... (Score 1) 66

Homemade hovercraft used to be a big thing since at least the '50s or '60s (and for all I know still are). Typically made by putting a prop on a vertical-axle lawnmower engine and building a simple vehicle body with a fan shroud in the middle.

There was a classic disaster that happened to a LOT of people who did this:

After they'd played around on land with it for a while they'd decide to test how it would perform on water. So they'd take it down to the local park-on-a-lake, fire it up, and drive out onto the lake.

It would work fine ... for a few minutes. Just long enough to get maybe 20 feet or so, over well over-their-heads water...

Then the spray it was kicking up and sucking back around the motor on its way to the fan would finally short out the spark wiring. Oops!

Of course they usually hadn't included any floats...

Comment Illegal in Ann Arbor. (Or so I've heard.) (Score 1) 66

No, flying isn't the correct word.

Story I heard, back in the '60s. (Don't know if it's true, unfortunately. But I think we have some Ann Arborites here who might check the city ordinances.)

Plans had been published for making homemade hovercraft with a salvaged lawnmower engine. Stand on it like a Segway and steer by leaning.

Kid had made one and decided to take it down the LOOOONG, somewhat steep, slope of Hill street one night. (I shiver at the thought of how fast that would be going near the bottom...)

Cops had a radar trap and clocked him at freeway speeds. Issued him a ticket.

He fought it, claiming that the cops had no jurisdiction because he was flying, not driving. Didn't touch the ground. Take it up with the FAA.

Traffic court judge (rightly or wrongly) agreed that this might be true and the cops hadn't proven jurisdiction, so he dismissed the ticket.

City Council banned hovercraft within the city limits shortly thereafter. B-b

Comment Re:Try to do something right (Score 1) 120

Did you ever write a program? Did it work the first time, doing exactly what it was supposed/specified to do?

Did you ever figure that was an adequate excuse?

Of course not.

Not in what you say isn't the truth, because any software that hasn't been shaken down is usually pretty bad, but using the "first time" as an actual reason for insecure software? Completely unacceptable. If you worked for me with that attitude, you might end up in the mail department where you could have an easier job.

You obviously both misparsed my statement and aren't aware
of how *I* do software development.
It includes beating the HELL out of any piece of software before
releasing it (with a full coverage test suite built into the make
mechanism in a way that causes the build to fail if a unit test
fails.)

I've developed a methodology that lets me deliver such a fully
debugged software components, with test suite blazingly fast,
as well. It takes me about three times as long as it takes a
more typical programmers to get a new component of similar
size and complexity to successfully compile and link (but not
run correctly) after a moderate feature change.

And I'm thus familiar with some of the pathologies of
people who administer programmers with insufficient
insight into what they're doing and their modes of talking
about it. Because I'm so fast I don't generally report
progress until a component is DONE. Result: Some
administrators have compared my delivery of a complete,
polished, from-scratch, component to one debug iteration
of other team members. This lead to actual publication of
a statement to this effect: "[Ungrounded Lightning Rod]
takes three times as long as anyone else, but his stuff
usually works the first time."

I've been referred to as "a god" in hushed tones (over a
nearly non-existent bug rate in a ten thousand line application),
and had a colleague comment that I was the only person he'd
rust to program an artificial heart for him.

So I'm quite aware of how to make software solid.

My point was not making excuses for poor programmers.

My point was that commercial software operations usually
have management pathologies that lead to measuring
function and not measuring (or rewarding) security.
There's a lot of WORK involved in making software secure
and doing it is usually penalized rather than rewarded. So you
have to expect commercial software to USUALLY be riddled
with security bugs.

(Which is why I migrated to hardware design about 15 years ago.
The non-recurring costs of a bug-fix respin as SO high that
administrators often appreciate and reward solid design and
execution.)

Comment Re:over the top but! (Score 1) 120

And the other side of that coin is finding it and reporting it. Then checking back x time later. Where they did nothing then say, why were you looking again?

How about:

1) To find out if the data was pulled down yet.
2) To be even nicer guys by waiting until the data WAS pulled down to run the story that would give tens of thousands of identity thieves a valuable present.

Comment Re:Try to do something right (Score 4, Insightful) 120

Or you know... people could start writing decent secure code to begin with... :)

Did you ever write a program? Did it work the first time, doing exactly what it was supposed/specified to do?

Took a lot of debugging and error correction, didn't it? Even if you are a programming expert.

Now write a program where "what it's supposed to do" includes "not get cracked and used by any malware, known or unknown, past or future".

Think you'll get THAT right the first time? Even if you are a security expert?

Comment Typos! ARRRRGH! (Score 1) 365

Correcting typos:

Spun out of Internal Revenue in 1886.
Shot and killed the son and sniped and killed the (nursing at the time) wife over a FIVE dollar tax matter, not a five hundred buck bill.

(ATF is also noted for throwing a pregnant woman against a wall - she later miscarried - and stomping a kitten to death just to drive home how powerless a raid target was to make them responsible for their actions. Shooting the family dogs at the start of a raid, for the raiders' convenience, is routine.)

Slashdot Top Deals

Never ask two questions in a business letter. The reply will discuss the one you are least interested, and say nothing about the other.

Working...