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Comment: But seriously... (Score 1) 161

by Ungrounded Lightning (#47571239) Attached to: The Problems With Drug Testing

What does this story have to do with Linux?

I assume you were going for "funny".

But on the off chance you (or some reader) is asking this seriously...

Slashdot is about things that are of interest to nerds. The approval process for new drugs (which might save, enhance, damage, or end their lives) is one of those subjects.

Comment: Re:Update cycles (Score 1) 219

by Pharmboy (#47569737) Attached to: How long ago did you last assemble a computer?

I tend to buy boxes with fairly high end parts (not expensive, just high quality), and when I built them I did the same. High end enough that I really didn't have to upgrade until everything was no longer "state of the art", so no parts to recycle in.

My ooold computer has a Q9550 and 8 gigs of ram, just as I ordered it. It is still pretty usable as a daily backup video player, and not bad for midline gaming like Portal 2, Goat Simulator, etc. Upgraded the video 3 years ago, $150-175 for what was then a steal.

5 years old, and the CPU is still on the front page of Passmark, at >4000 pmarks. Not bad. Paid around 1800 without monitor. Upgraded to 7 Pro over Vista, but even the original install is intact. Hard to beat that kind of stability, and not convinced you can build it by hand anymore.

Comment: Re:He just doesent' get it.. (Score 3, Insightful) 494

by metlin (#47569335) Attached to: Jesse Jackson: Tech Diversity Is Next Civil Rights Step

As an Indian American, while I agree with the spirit of your comment, please remember that we are just as badly affected by the H1B visas as any other Americans.

Unfortunately, we are all cast in the same light, our background, academic qualifications, or experience notwithstanding.

Comment: No, it isn't and they don't (Score 1) 161

by jd (#47556521) Attached to: OKCupid Experiments on Users Too

The Internet is not powered by experiments on humans. Not even in the DARPA days.

No, websites do NOT experiment on users. Users may experiment on websites, if there's customization, but the rules for good design have not changed either in the past 30 years or the past 3,000. And, to judge from how humans organized carvings and paintings, not the past 30,000 either.

To say that websites experiment on people is tripe. Mouldy tripe. Websites may offer experimental views, surveys on what works, log analysis, etc, but these are statistical experiments on depersonalized aggregate data. Not people.

Experiments on people, especially without consent, is vulgar and wrong. It also doesn't help the website, because knowing what happens doesn't tell you why. Early experiments in AI are littered with extraordinarily bad results for this reason. Assuming you know why, assuming you can casually sketch in the cause merely by knowing one specific effect, is insanity.

Look, I will spell it out to these guys. Stop playing Sherlock Holmes, you only end up looking like Lestrade. Sir Conan Doyle's fictional hero used recursive subdivision, a technique Real Geeks use all the time for everything from decision trees to searching lists. Isolating single factors isn't subdivision because there isn't a single ordered space to subdivide. Scientists mask, yes, but only when dealing with single ordered spaces, and only AFTER producing a hypothesis. And if it involves research on humans, also after filling out a bloody great load of paperwork.

I flat-out refuse to use any website tainted with such puerile nonsense, insofar as I know it to have occurred. No matter how valuable that site may have been, it cannot remain valuable if it is driven by pseudoscience. There's also the matter of respect. If you don't respect me, why should I store any data with you? I can probably do better than most sites out there over a coffee break, so what's in it for me? What's so valuable that I should tolerate being second-class? It had better be damn good.

I'll take a temporary hit on what I can do, if it safeguards my absolute, unconditional control over my virtual persona. And temporary is all it would ever be. There's very little that's truly exclusive and even less that's exclusive and interesting.

The same is true of all users. We don't need any specific website, websites need us. We dictate our own limits, we dictate what safeguards are minimal, we dictate how far a site owner can go. Websites serve their users. They exist only to serve. And unlike with a certain elite class in the Dune series, that's actually true and enforceable.

Comment: Nope. Need 250 plus margin on mountains. (Score 1) 117

But 200 miles certainly covers any and all local in-town and in-area travel possibilities, and nearly everything but very long distance travel.

Nope. You need 250 plus a safety margin - on mountains for part of the trip.

In my case that's half a commute between my Silicon Valley townhouse and my edge-of-Nevada ranch. But that's virtually the same trip as between Silicon Valley / San Francisco Bay Area and many weekend vacation spots: Lake Tahoe ski resorts, Reno gambling, gold country camping, etc.

Make a car that can do 30-mile-one-way commute efficiently and has this 250-and-chage range, and a Northern Californian who works near the coast and blows off steam near the CA/NV interface only needs ONE vehicle. (So it takes four to six hours to charge when you get there and when you get back - so what? It'll be parked longer than that anyhow.) Less and he/she needs TWO, with all the environmental impact of building both. Further, the long-range one is a gas hog by comparison.

Comment: Yes it does. But... (Score 1) 117

Does a loaded F-150 even get 500 miles on a single tank of gas?

Yes, it does.

But it's a 37 galon tank.

I love everything about my F-150 Lariet EXCEPT the gas mileage (and the refusal to pan the weather map except when the vehicle is stopped). Unfortunately, when you have to haul several tons up and down a mountain or across an unpaved desert from time to time, it's hard to avoid a tradeoff in that department.

Comment: Re:The failure mode is transformer core saturation (Score 4, Interesting) 90

by Ungrounded Lightning (#47537135) Attached to: The Truth About Solar Storms

... the induced DC from a solar storm isn't as instantaneous as a lightning strike. It takes minutes to develop, which leaves time to disconnect the lines and affected transformers if they are properly monitored.

But ARE they monitored for DC? It's not a usual problem.

Warnings on the order of minutes might be useful if the transmission line were the only one invoved. Unfortunately, the power grid is a GRID. Lots of multiple, parallel, transmission lines, and many, many, more going elsewhere and often creating loops.

Redundancy is a good thing in most situations. But when you have to drop a high line, and don't drop all the others simultaneously, you shift the load onto those that are still connected. When you're cutting off because you're near the limit - either due to heavy load at the time or because of the DC issue - you can drive the others beyond their limits (or throw things out of sync and add a bunch of "reactive current" to the load) and create a cascading failure. (Indeed, this is how the first Great Northeast Blackout occurred: Three of a set of four high-lines crossing the St. Lawrence Seaway near Niagra tripped out, and the redistributed load put one after another generator above its limits, blowing its protective breakers and making it progressively harder on those remaining.)

Gracefully shutting down the grid is not something you do on a couple minutes' notice, even if you have a plan in place.

As I understand, the induced DC is something on the order of hundreds of volts, which is much less than the tens of thousands of volts transmitted across ordinary high voltage transmission lines; disconnecting them should not result in arcing problems across the switches.

First, the problem with the induced near-DC is not the voltage, but the current. Transformers and transmission lines have as little resistance as possible, because it's pure loss of valuable energy. The magnetizing alternating current (i.e. the part of the AC that's there all the time, not just when there's a load) is also limited by the inductance of the transformers, but that doesn't impede the direct current at all. A couple hundred "DC" (very low frequency - fractional cycle per minute) volts, induced for minutes around the loop, can drive a hysterical amount of current.

Once the transformer is saturated, most of the damage comes, not from the direct current, but from the line power, which ends up dissipating lots of energy in the transformer. Meanwhile, at these voltages and currents, the switches that interrupt the AC are largely dependent on the momentary off time as the cycle reverses to quench the arc. If, say, the event happened when the line was running at about half its rated load, the direct current will be higher than the alternating current, so there will be no off time. This can keep the current flowing even through an open breaker (while dissipating megawats IN the breaker). Interrupting DC is MUCH harder than interrupting AC.

Heck, at these voltages even interrupting AC is hard. (The video is of an interrupter where the jet of arc-suppressing gas failed for one leg.)

Comment: The failure mode is transformer core saturation. (Score 5, Informative) 90

by Ungrounded Lightning (#47536253) Attached to: The Truth About Solar Storms

High induced votlages in open wires are a problem, but they're not the big one.

The biggie is common-mode currents in long high-voltage transmission lines adding a strong DC component to the current in the substation transformer windings - high enough that when the same-direction peak of the AC's cycle adds to it, the core saturates. Then the inductance of the transformer drops to the air-core value and no longer substantially impeeds the current.

The current skyrockets. The resistive heating of the windings (and the force on the wires from the magnetic fields) goes up with the SQUARE of the current. The windings quickly soften, distort, form shorted turns, melt, open, short out to the frame, etc. The transformer is destroyed, or committed to a self-destructive progressive failure, in just a handful of such cycles - too fast for the circuit breakers to save them (even if they DO manage to extinguish the arcs with the substantial DC component to the current.) Even if the transformer doesn't explode and throw molten metal, gigawatt sustained arcs, and burning oil (or burning-hot oil replacement) all over the substation area, it's still dead.

This happens to MANY of the giant transformers in the power grid. Each set of three transformers that has one or more failed members means a high-voltage transmission line that is shut down until the transformer is replaced.

There are essentially no spares - these are built to order. Building one takes weeks, and there are few "production lines" so little parallelism is available. What is destroyed overnight will take years to replace, while each intercity power transmission line is not functioning until the transformers at its end ARE replaced.

The current occurs because the transformers are organized in a "Y" arrangement, and the center of the Y is grounded at each end (to prevent OTHER problems). The transformers have enough extra current handling capacity to avoid saturation from the DC through that center connection to/from ground from ordinary electrical and solar storms - just not a giant one like we get every couple centuries.

The solution is to put a resistor in that ground connection, to limit the DC in the lines (and dissipate the energy it represents). Indeed, a few lines have such resistors already.

But a suitable resistor is a box about the size of one of the transformers. It's very expensive. And it only makes a substantial difference to the operation of the lines in such a once-in-centuries event. So most executives don't spend the money (and get dinged for costing the company millions) to put them in, to prevent a failure mode that hasn't happened in the generations since Tesla and Westinghouse invented the three-phase long-line power grid.

Or at least they don't until the regulators or their stockholders require it. Which means said decision-makers need a little educational push to decide it's worth the cost and get it done.

Thus articles like this. B-)

Comment: Presbyopia (Score 1) 547

by Ungrounded Lightning (#47525653) Attached to: Laser Eye Surgery, Revisited 10 Years Later

I'm up around retirement age. My eyes don't chage focus much at all. So I have to swap lenses to go from distance to close-up vision. (Yes I could use some kind of bi/tri/progressive-focal lenses. But at the moment swapping is adequate for me.)

Until they find a way to correct presbyopia (and they don't see to be even researching it), I'd still have to don/remove glasses anyhow. With my extreme astigmatism, extreme nearsightedness, and substantial age, I'm not a good candidate for lasic and stand a substantial chance of visual artifacts from it. I'm also a target shooter, so my glasses double as eye protection.

Given all this, the potential benefits for me would be small and the risks and cost oughtweigh them.

But if they ever find a way to fix presbyopia the equation could change substantially.

It seems that more and more mathematicians are using a new, high level language named "research student".

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