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Comment: But seriously... (Score 1) 160

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: 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.

Comment: Re:"You ate the poison mushroom!" reflex. (Score 1) 154

It's when I'm bending, twisting, picking up objects, etc. that I get vertigo.

Which is what's expected. You spend most of your time upright, so your brain gets a lot of experience with the chaged response of your inner ear. So it learns to interpret the modified signals more appropriately.

But when you bend down, twist, pick things up, and otherwise get into rarer positions and motions, you're in a set of conditions where the signals you're getting are not what the brain has yet figured out. Meanwhile, some of these postures also make you lose many of the visual cues of your position, throwing you into dependence on your muscle and (defective) ear signals. Bingo: Vertigo attack.

You MAY be able to reduce the amount of severity of the attacks by doing such postures as exercise, to help you learn to map more of the range of your ears' signals. Assuming, of course, you can stand the vertigo while doing the exercises, and/or can stop before the attack gets very strong.

Comment: Re:Which is why FAST flicker still causes vertigo. (Score 1) 154

Electronic ballasts don't run at line frequency, they are many times higher (1,000hz+), so that issue should be eliminated.

Electronic ballasts may indeed produce thousands of flashes per second. But they're powered by a "raw" power supply - a recitfier and filter capacitor that is in turn powered by the line, which comes and goes 120 times per second (or 100 in much of Europe).

If the filter capacitor is large enough that it doesn't discarge appreciably before it is recharged by the next half-cycle, the individual pulses produce about the same amount of light, the repitition rate of the pulses is close to constant, and thus the average brightness is close to stable over the line power cycle.

If the filter capacitor is smaller, it discharges substantially during the low-voltage parts of the cycle. The individual flashes get dimmer when the voltage droops and the repititition rate may also change. The average across several consecutive mini-flashes tends to track the input voltage.

If the capacitor is still smaller, the voltage may go so low that the high-frequency oscillator actually stops during the low voltage parts of the input cycle. The flicker may actually become substantially WORSE.

Bigger capacitors cost more. So guess what the cheap, commodty, lamps get.

Comment: Wait until you're older. B-b (Score 2) 154

There are two sets of muscles for eye movement - one for convergence, which rotates the eyes, the other for focus, which reshapes the eyes...

The latter system also reshapes the lens.

Unfortunately, as you age your lenses stiffen up and/or the muscles get weaker, and that system gradually degrades. (This "disease of age" (presbyopia) becomes significant pretty early - about mid 30s.)

(By the way: The eye rotation is actually THREE axis, although the motion around the line-of-sight is pretty limited. {Look in a mirror and rotate your head right-left to see it.} Apparently evolution found matching the image rotation by slightly rotating the eyes to be less expensive than a layer of image-rotation logic in the brain.)

Comment: Which is why FAST flicker still causes vertigo. (Score 5, Interesting) 154

I find that any kind of response time lag between my inputs and the real world, especially when it varies, is what makes me sick ...

My wife has vertigo. Her attacks can be triggered by fluorescent or high-pressure arc lights where the flicker rate is above the flicker-fusion rate of the eye. (This makes trips to warehouse stores problematic - they have to be short or she'll be down for the rest of the day. That's hard at, say, Costco.)

I used to wonder how this could be, and finally realized that the "strobe light" effect produces small, but significant, errors in observed position of the background items (shelves, etc.) that she uses for reference to balance despite the damaged inner ear.

When they first began using fluorescent lights in factories - in the days before guards over moving machinery were common - the worker injury rate went 'way up. Turns out the lights made the AC-powered motors, turning at or near an integer fraction of the line frequency, look like they were stopped or only moving slowly.

The fix was to build the light fixtures in two-tube versions, with a capacitor and an extra inductor in the balast, so the "lead lamp" and "lag lamp" would light at a quarter-cycle offset. In combination with suitably persistent phosphors this made them largely fill in each other's dim times, enough to make fast-moving parts blur and look like they were moving. For large arc lights, a similar fix was to arrange them so adjacent lamps were distributed among the three phases of the power feed, rather than having rows or patches of lights all flickering in unison.

Unfortunately, this lore has apparently been lost - at least outside the specialists wiring factories full of moving parts. Warehouse stores have rows and sections of arc lighting all wired to the same phase. I'm not sure, but I don't think the new electronic ballasts for flourescent lights do the lead-lag thing, OR have enough raw filtering capacitance to power the lamp through the phase reversals. (And then there's LED lamps...)

It's not a safety hazard these days, now that OSHA rules have all the fast-spinning machinery covered with guards. But for those with vertigo it's a big problem.

Comment: "You ate the poison mushroom!" reflex. (Score 4, Informative) 154

The human body has three systems for balance - Inner ears (3-axis accellerometers and "rate gyros"), visual modeling, and muscle/tendon position & stress sensors - and needs any two to balance, stand, and walk properly.

It also has a reflex: When two of them disagree (particularly visual vs. ear), it is interpreted as "You just ate a neurotoxin! Get it out NOW and we MIGHT survive it!"

Thus nausea, projectile vomiting, explosive diahrrea, and clothes-soaking sweating if the mismatch is strong. If it's smaller - nausea. ("Whatever you just ate may have been toxic or spoiled. So you're not going to like it anymore.")

Of course other things than being poisoned can trigger it:

Diseases that temporarily incapacitate or permanently damage the inner ear are one class. (For instance, Meniere's Disease, where the pressure-relef valve for the inner ear sticks, the pressure rises, and the membranes with the sensory nerves tear. Result: Sudden extremem vertigo attack - hours on the floor - followed by days or weeks of gradually reduced incapacity until the brain maps out the change to the ear - followed by another tear and repeat indefinitely. Very high suicide rate.)

Vechicles, where you may visually fixate on the accellerating inside rather than the surroundings, are another: Cars, boats, ariplanes (and the corresponding car/sea/air sicknesses) are notorious, as are carnival rides and trains. For relief, make a point of looking at the horizon or otherwise the exterior. Eventually the brain may learn "I'm in a vehicle. Ignore the weird signals from the ears. (That's why vertigo sufferers may NOT have attacks in MOVING vehicles...)

And, of course, VR mismatches - to the point that there is a term of art: "Barfogenisis" (I hear the lengths of some of the rides at Disneyland are calibrated so they end and the crowd is out into the hall just BEFORE the effect would become pronounced.)

Comment: Our city imposes a 3% tax on utilities (Score 1) 148

by Ungrounded Lightning (#47472649) Attached to: US House Passes Permanent Ban On Internet Access Taxes

Our city imposes (suckered the voters into approving) a 3% tax on utilities - comm, power, gas, ... - and has for several years. I think that includes internet service (which is pretty steep around here). My wife and I have been fighting this law and its renewal. (It is driving businesses out of the city - they can cut their costs substantially by relocating just over the line - and thus both blighting the city and cutting other tax revenue.

I think I need to do a little checking to see if they ARE taxing the internet part of the phone bill and if that's prohibited federally. Zapping them for a refund (for everybody, for several years worth) might get their attention. B-)

Comment: It has nothing to do with the target. (Score 1) 183

What about consumer electronics (washing machines, microwaves, smartphones, routers, AP's) or critical industrial systems
where I would image RTOS to be necessary (VxWorks, QNX) ? I can't imagine Windows CE dominating in those spaces.

You seem to be missing something here.

We're not talking about the target. We're talking anout the platform on which the program for the target is built.

This is where the editors, version control system, compilers, linkers, profilers, prom burners, in-circuit emulators, etc. are running. The operating system here has no more to do with the operating system on the target (other than supporting the tools that build it) than the operating system on the mainframe where Gates and Allen developed Altair BASIC had to do with the BASIC language or the guts of their interpreter.

Comment: It's a tool vendor, not a target, issue. (Score 1) 183

But you see you are in the Windows CE embedded niche. Your vision is clouded.

I'm not in a "windows CE embedded" niche and the grandparent poster is right.

It's not an issue with the target. It's an issue with the platform(s) supported by the development tool vendors and the chip manufacturers.

For instance: With Bluetooth 4.0 / Bluetooth Low Energy (BLE), two of the premier system-on-a-chip product families are from Texas Instruments and Nordic Semiconductors.

TI developed their software in IAR's proprietary development environment and only supports that. Their bluetooth stack is only distributed in object form - for IAR's tools - with a "no reverse engineering" and "no linking to open source (which might force disclosure)". IAR, in turn, doesn't support anything but Windows. (You can't even use Wine: The IAR license manager needs real Windows to install, and the CC Debugger dongle, for burning the chip and necessary for hooking the debugger to the hardware debugging module, keeps important parts of its functionality in a closed-source windows driver.) IAR is about $3,000/seat after the one-month free evaluation (though they also allow a perpetual evaluation that is size-crippled, and too small to run the stack.)

The TI system-on-a-chip comes with some very good and very cheap hardware development platforms. (The CC Debugger dongle, the USB/BLE-radio stick, and the Sensor Tag (a battery-powered BLE device with buttons, magnetometer, gyro, barometer, humidity sensor, ambient temp sensor, and IR remote temp sensor), go for $49 for each of the three kits.) Their source code is free-as-in-beer, even when built into a commercial product, and gives you the whole infrastructure on which to build your app. But if you want to program these chips you either do it on Windows with the pricey IAR tools or build your own toolset and program the "bare metal", discarding ALL TI's code and writing a radio stack and OS from scratch.

Nordic is similar: Their license lets you reverse-engineer and modify their code (at your own risk). But their development platforms are built by Segger and the Windows-only development kit comes with TWO licenses. The Segger license (under German law), for the burner dongle and other debug infrastruture, not only has a no-reverse-engineering clause but also an anti-compete: Use their tools (even for comparison while developing your own) and you've signed away your right to EVER develop either anything similar or any product that competes with any of theirs.

So until the chip makers wise up (or are out-competed by ones who have), or some open-source people build something from scratch, with no help from them, to support their products, you're either stuck on Windows or stuck violating contracts and coming afoul of the law.

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