I'd argue he'd take on way more risk had he not prevented the accident. There were two scenarios: one - he gets ahead of the other truck, passes the upcoming intersection on a green light, and everything is fine and dandy. Other scenario: there's red on the upcoming intersection. The truck crashes into the traffic right in front of him. Cue plenty of car crashes, possibly with some airborne cars, and suddenly things start looking quite bleak. I'd pity his kids had he had to stop at that red light. He replaced a 50-50 chance of red light with, say, a 1-in-10k chance of something going wrong with the stopping maneouvre.
The only currently known foolproof, non-intrusive failsafe for an unconscious driver involves an eye motion tracker. As long as there is saccadic activity, the driver is conscious. No saccades (even with open eyes): we have a daydreamer or a sleeper. Those things weren't exactly cheap just a decade ago, even if one were to optimize them for mass production. These days all you need is a high resolution camera chip coupled into a fast CPU, and use of well-published algorithms. The chip should be, say, 5 megapixels+, but you only refresh a small (VGA or so) sub-window that tracks the head -- say at 100Hz. For initial eye detection, you can scan the chip at a lower overall resolution.
So yes, I agree with you that cars should have alertness detectors, but it's not exactly a walk in the park. There are quite a few companies out there that could pull it off, but there's legislation and other crap that would need to be sorted out first.
The parent is interesting for its entertainment value.
Gold's value is not like diamond value -- its value is not because of what people think, but because it costs a lot to extract it. Way more than you imply.
Typically, gold is extracted from ores that have gold content measured in single ppms -- that's parts per million.
To give you an idea of what that means. All of the gold ever extracted would fit in a cube 20.3m on edge.
This gold would cover Times Square area in a layer about 1.3m thick (area is 6500 m^2 if you razed the buldings between 7th and Broadway, and assumed TS extends between 42nd and 47th streets).
All of the stone discarded from that mining, at assumed 2.5ppm ore concentration, would cover City of New York in a layer 4 times as thick. Or, it'd cover the entire State of New York in a layer an inch thick.
This gives you an idea of the scale of gold mining operations. If you think digging that much rock should be cheaper, you're welcome to get investors, buy some mining leases, undercut everyone else, and start buying up competitors.
Yeah, Sun could have simply messed up. But in the olden days bootloaders that could snatch up something via TFTP or even NFS were a mainstay of Unix workstation world. It'd be weird, although not unimaginable, for a sun Unix WS to come without one.
I can't believe that no one has seemingly mentioned neooffice's future. Its UI is written in Java. Neooffice is a nice OS X port of openoffice.org, with many platform-specific improvements -- it offered native OS X support way ahead of oo.org's.
Without a JVM offering a native GUI experience on OS X, neoffice project is basically screwed. Re-developing the GUI in objc would probably take years.
I would otherwise agree, but the problem is that a lot of MacPorts just stop working on Snow Leopard. wxWindows doesn't work yet. Nothing that uses native (non-X11) gtk works -- gimp used to work on native gtk under OS X 10.5. I learned it the hard way.
Be careful now -- are you saying that if you simply buy, say, 50% more PCs than you need, that won't cover breakdowns? As in "oh, it's dead, let's swap it out"? This is about as labor-unintensive as it gets. Buy 1500 PCs for $500 instead of 1000 for $1000, and you still have money left over ($0.25M, in fact) to cover you and your PFYs bar trips. You don't have to do any troubleshooting at all: if it doesn't work, you simply swap it out. Whenever you need to do something else to clear you head up, as we all do sometimes, you can pick up a "dead" machine, troubleshoot and replace what's needed -- all from your own spare pool.
In well run Windows shop, you should have centralized imaging set up, so I presume that bringing up a new machine should be something that only takes unpacking, setting it on the desk, connecting the network cable, putting in the imager install USB stick, and rebooting.
So, at 120VAC RMS, the current will be around 5 microamperes (5E-6A). Hardly worth mentioning. You got your orders of magnitude wrong -- you gave a result as if the capacitor was 100nF; then the current would be 5 mA -- enough to jolt you.
HUH? I don't think that any sort of unprotected (outside of the enclosure) decorative coating such as enamel, powder paint, spray paint, anodized layer on aluminum, etc. can be considered a part of any insulation scheme. In all electrical insulation system analyses, decorative coatings don't exist.
If you're looking at enamel within the enclosure, then IIRC it needs to be protected from abrasion, so it really works on things that don't rub on each other. Fine in a transformer and not much else, I'd say.
There are infinitely many real numbers, but only some of them -- still infinitely many -- have a finite positional representation in at least one base (decimal or not). For every such finite positional representation, there exists its infinite twin that we construct as follows: subtract one at the least significant nonzero digit (LSD) position, borrowing as necessary, then append a infinitely many largest digits in the positional system (9 in decimal, 1 in binary, F in hexadecimal, etc) after the LSD.
Nothing ever approaches 1, because we're talking of decimal representations of different numbers vs. decimal representations of same number.
0.999 is a different number than 0.9999, is a different number than 0.(9)... You can't treat 0.(9) like it had any less than an infinite amount of digits.
Yes, it's true that if you keep adding nines to 0.9, you get numbers that get closer and closer to 1. But this got nothing to do with 0.(9)... -- the quirky decimal representation of number one.
You have to separate numbers from their representation, especially representation in a positional system. There is only one number 1 in the set of real numbers. Yet the decimal positional representation is quirky and got two representations for that number: 1 and 0.(9)...
So the whole issue is not that of numbers, but of representations: saying that 0.(9)... equals 1 like those were somehow different numbers is somewhat disingenuous. 0.(9)... and 1 are different decimal positional representations of same Real number one.
I think that the real problem is that people aren't quite told in school that same number can have multiple representations in a positional system. It seems weird because we think those are, somehow, "special" cases. There's an infinite amount of real numbers that have two representations in the decimal positional system.
Wet air causes corona discharges. Their effect, in bulk, is same as if you'd attach a resistor between each phase pair, and one between each phase and ground. Wet air is not 'an electrical short thing' anymore than a transformer with a resistive load would be.
Let's see if you're right about 0.25hp it in terms of resolution of measuring instruments. Assume you're doing power measurements using a 6.5 decimal digit instrument, with p-p noise of one least significant digit. That lets you measure 0.3ppm, or 0.3W in a MW. Assuming you have a transmission line with a 500MW load, then yes -- you could detect adding ~160W of load.
Now there are several problems that I see:
0. Do they actually have that sort of resolution available for power measurements on HV transmission lines. We're talking 1ppm. You can't exactly attach an electrician's power meter to a 100kV line -- those instruments probably cost ~ 10k USD, and are few and between. You need an isolated current transformer with isolation rated for, say, line voltage * 1.5, and a voltage divider stack, similarly rated, with accuracy, say, an order of magnitude or two away from your resolution -- so that the results will have any real-life meaning.
From what I know, making a 100+kV divider that maintains accuracy down to say 10ppm over industrial temp range is no small feat; those aren't exactly instruments that you can throw ate every which large substation.
1. How much does it fluctuate due to changes in load -- the value is not steady, so you can't exactly see anyone in particular doing anything. I don't know what is, say the typical p-p power change in one second on a large line (>10MW load). This would be important.
2. How much does the load fluctuate on a large (say ~500kV) line with no loads attached -- merely due to corona discharges and such. And, moreover, what is this baseline load.
3. How often do they run the line with all loads disconnected (no transformers, no nothing, all switches open).
4. If they run tests with large substation transformers in the circuit, but with load sides of those transformers open, what's the magnitude of load presented by unloaded transformers (they have radiators for a reason), and how much does it change due to weather conditions (temperature, humidity) -- say you measure on Monday, then Joe Schmoe starts stealing on Tuesday, can you see the difference on Wednesday?
5. Transmission systems are dynamical things, sometimes to a point of becoming runaway-unstable, there are plenty of Ph.D.s on the topic. From what I recall from reading about powerplant commissioning, sometimes just maintaining the power flow going in the correct direction so that your generators don't absorb all of it can be something that get to brag about in the evening over beer. I don't think you can measure any effects of a couple, or even dozes, of hp of loading in a large transmission system that's operating normally. And that's what we're talking about here: someone "stealing" from a multi-100kV line, not from a small local substation where arguably it'd be comparatively trivial to detect.
And so on. All I see are real metrological problems, and the overall accuracy and sensitivity of the measurements you call for is more to be found in a lab than in the field.
Not in high voltage transmission. At 100kV+, the losses are such that you can't power the line to measure losses from an "instrument" -- you need something that can provide tens or hundreds of kilowatts, on a dry day without much winds. The cable itself is not insulated, either -- we're talking air lines here. For lines buried in the ground, I'd think you'd have closed hydraulic circuits that are used for line integrity monitoring.
Be careful with using "strength of a magnetic field" like you propose. When you have a typical AC transmission line, a single phase wire is but a one-half transformer turn. If I remember my electromagnetics correctly, your secondary winding can be as large as you wish, if the current passes through your solenoid. You could have a solenoid that's a kilometer in diameter, and as long as one phase would pass through it, the induced current (given some load) would be same as if the solenoid was not-quite-touching the phase wire. Things change, of course, when your solenoid's plane does not intersect the phase wire. I think I'll run a little experiment later today.
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To add some first hand experience to this: scraping a concrete wall with the side of your car is plenty loud, especially at 30+mph.
No. But I'm all ears.
I'd argue he'd take on way more risk had he not prevented the accident. There were two scenarios: one - he gets ahead of the other truck, passes the upcoming intersection on a green light, and everything is fine and dandy. Other scenario: there's red on the upcoming intersection. The truck crashes into the traffic right in front of him. Cue plenty of car crashes, possibly with some airborne cars, and suddenly things start looking quite bleak. I'd pity his kids had he had to stop at that red light. He replaced a 50-50 chance of red light with, say, a 1-in-10k chance of something going wrong with the stopping maneouvre.
Airbags won't deploy in a rear impact. They aren't supposed to.
There was very little risk. Delta-V was small.
The only currently known foolproof, non-intrusive failsafe for an unconscious driver involves an eye motion tracker. As long as there is saccadic activity, the driver is conscious. No saccades (even with open eyes): we have a daydreamer or a sleeper. Those things weren't exactly cheap just a decade ago, even if one were to optimize them for mass production. These days all you need is a high resolution camera chip coupled into a fast CPU, and use of well-published algorithms. The chip should be, say, 5 megapixels+, but you only refresh a small (VGA or so) sub-window that tracks the head -- say at 100Hz. For initial eye detection, you can scan the chip at a lower overall resolution.
So yes, I agree with you that cars should have alertness detectors, but it's not exactly a walk in the park. There are quite a few companies out there that could pull it off, but there's legislation and other crap that would need to be sorted out first.
s/what people think/what people are made to think by DeBeers/
The parent is interesting for its entertainment value.
Gold's value is not like diamond value -- its value is not because of what people think, but because it costs a lot to extract it. Way more than you imply.
Typically, gold is extracted from ores that have gold content measured in single ppms -- that's parts per million.
To give you an idea of what that means. All of the gold ever extracted would fit in a cube 20.3m on edge.
This gold would cover Times Square area in a layer about 1.3m thick (area is 6500 m^2 if you razed the buldings between 7th and Broadway, and assumed TS extends between 42nd and 47th streets).
All of the stone discarded from that mining, at assumed 2.5ppm ore concentration, would cover City of New York in a layer 4 times as thick. Or, it'd cover the entire State of New York in a layer an inch thick.
This gives you an idea of the scale of gold mining operations. If you think digging that much rock should be cheaper, you're welcome to get investors, buy some mining leases, undercut everyone else, and start buying up competitors.
What AC said above: even if Moon was solid, 24k gold, it'd not make economical sense to mine it there. End of story.
Try doing microelectronics without gold. LOL.
Yeah, Sun could have simply messed up. But in the olden days bootloaders that could snatch up something via TFTP or even NFS were a mainstay of Unix workstation world. It'd be weird, although not unimaginable, for a sun Unix WS to come without one.
Didn't it have a way of doing an OS load via NFS or somesuch in the bootloader?
I can't believe that no one has seemingly mentioned neooffice's future. Its UI is written in Java. Neooffice is a nice OS X port of openoffice.org, with many platform-specific improvements -- it offered native OS X support way ahead of oo.org's.
Without a JVM offering a native GUI experience on OS X, neoffice project is basically screwed. Re-developing the GUI in objc would probably take years.
I would otherwise agree, but the problem is that a lot of MacPorts just stop working on Snow Leopard. wxWindows doesn't work yet. Nothing that uses native (non-X11) gtk works -- gimp used to work on native gtk under OS X 10.5. I learned it the hard way.
Be careful now -- are you saying that if you simply buy, say, 50% more PCs than you need, that won't cover breakdowns? As in "oh, it's dead, let's swap it out"? This is about as labor-unintensive as it gets. Buy 1500 PCs for $500 instead of 1000 for $1000, and you still have money left over ($0.25M, in fact) to cover you and your PFYs bar trips. You don't have to do any troubleshooting at all: if it doesn't work, you simply swap it out. Whenever you need to do something else to clear you head up, as we all do sometimes, you can pick up a "dead" machine, troubleshoot and replace what's needed -- all from your own spare pool.
In well run Windows shop, you should have centralized imaging set up, so I presume that bringing up a new machine should be something that only takes unpacking, setting it on the desk, connecting the network cable, putting in the imager install USB stick, and rebooting.
I agree. Especially that fast-rotating electrical machines can be made quite small for the power delivered.
Reactance of a capacitor: R=1/(2*pi*f*C).
C=0.1E-9 (0.1nF)
f=60
R=26.5E6 (27 MOhms)
So, at 120VAC RMS, the current will be around 5 microamperes (5E-6A). Hardly worth mentioning. You got your orders of magnitude wrong -- you gave a result as if the capacitor was 100nF; then the current would be 5 mA -- enough to jolt you.
HUH? I don't think that any sort of unprotected (outside of the enclosure) decorative coating such as enamel, powder paint, spray paint, anodized layer on aluminum, etc. can be considered a part of any insulation scheme. In all electrical insulation system analyses, decorative coatings don't exist.
If you're looking at enamel within the enclosure, then IIRC it needs to be protected from abrasion, so it really works on things that don't rub on each other. Fine in a transformer and not much else, I'd say.
Epic explanation -- thank you!
More clearly:
There are infinitely many real numbers, but only some of them -- still infinitely many -- have a finite positional representation in at least one base (decimal or not). For every such finite positional representation, there exists its infinite twin that we construct as follows: subtract one at the least significant nonzero digit (LSD) position, borrowing as necessary, then append a infinitely many largest digits in the positional system (9 in decimal, 1 in binary, F in hexadecimal, etc) after the LSD.
Nothing ever approaches 1, because we're talking of decimal representations of different numbers vs. decimal representations of same number.
0.999 is a different number than 0.9999, is a different number than 0.(9)... You can't treat 0.(9) like it had any less than an infinite amount of digits.
Yes, it's true that if you keep adding nines to 0.9, you get numbers that get closer and closer to 1. But this got nothing to do with 0.(9)... -- the quirky decimal representation of number one.
You have to separate numbers from their representation, especially representation in a positional system. There is only one number 1 in the set of real numbers. Yet the decimal positional representation is quirky and got two representations for that number: 1 and 0.(9)...
So the whole issue is not that of numbers, but of representations: saying that 0.(9)... equals 1 like those were somehow different numbers is somewhat disingenuous. 0.(9)... and 1 are different decimal positional representations of same Real number one.
I think that the real problem is that people aren't quite told in school that same number can have multiple representations in a positional system. It seems weird because we think those are, somehow, "special" cases. There's an infinite amount of real numbers that have two representations in the decimal positional system.
Wet air causes corona discharges. Their effect, in bulk, is same as if you'd attach a resistor between each phase pair, and one between each phase and ground. Wet air is not 'an electrical short thing' anymore than a transformer with a resistive load would be.
Let's see if you're right about 0.25hp it in terms of resolution of measuring instruments. Assume you're doing power measurements using a 6.5 decimal digit instrument, with p-p noise of one least significant digit. That lets you measure 0.3ppm, or 0.3W in a MW. Assuming you have a transmission line with a 500MW load, then yes -- you could detect adding ~160W of load.
Now there are several problems that I see:
0. Do they actually have that sort of resolution available for power measurements on HV transmission lines. We're talking 1ppm. You can't exactly attach an electrician's power meter to a 100kV line -- those instruments probably cost ~ 10k USD, and are few and between. You need an isolated current transformer with isolation rated for, say, line voltage * 1.5, and a voltage divider stack, similarly rated, with accuracy, say, an order of magnitude or two away from your resolution -- so that the results will have any real-life meaning.
From what I know, making a 100+kV divider that maintains accuracy down to say 10ppm over industrial temp range is no small feat; those aren't exactly instruments that you can throw ate every which large substation.
1. How much does it fluctuate due to changes in load -- the value is not steady, so you can't exactly see anyone in particular doing anything. I don't know what is, say the typical p-p power change in one second on a large line (>10MW load). This would be important.
2. How much does the load fluctuate on a large (say ~500kV) line with no loads attached -- merely due to corona discharges and such. And, moreover, what is this baseline load.
3. How often do they run the line with all loads disconnected (no transformers, no nothing, all switches open).
4. If they run tests with large substation transformers in the circuit, but with load sides of those transformers open, what's the magnitude of load presented by unloaded transformers (they have radiators for a reason), and how much does it change due to weather conditions (temperature, humidity) -- say you measure on Monday, then Joe Schmoe starts stealing on Tuesday, can you see the difference on Wednesday?
5. Transmission systems are dynamical things, sometimes to a point of becoming runaway-unstable, there are plenty of Ph.D.s on the topic. From what I recall from reading about powerplant commissioning, sometimes just maintaining the power flow going in the correct direction so that your generators don't absorb all of it can be something that get to brag about in the evening over beer. I don't think you can measure any effects of a couple, or even dozes, of hp of loading in a large transmission system that's operating normally. And that's what we're talking about here: someone "stealing" from a multi-100kV line, not from a small local substation where arguably it'd be comparatively trivial to detect.
And so on. All I see are real metrological problems, and the overall accuracy and sensitivity of the measurements you call for is more to be found in a lab than in the field.
Not in high voltage transmission. At 100kV+, the losses are such that you can't power the line to measure losses from an "instrument" -- you need something that can provide tens or hundreds of kilowatts, on a dry day without much winds. The cable itself is not insulated, either -- we're talking air lines here. For lines buried in the ground, I'd think you'd have closed hydraulic circuits that are used for line integrity monitoring.
Be careful with using "strength of a magnetic field" like you propose. When you have a typical AC transmission line, a single phase wire is but a one-half transformer turn. If I remember my electromagnetics correctly, your secondary winding can be as large as you wish, if the current passes through your solenoid. You could have a solenoid that's a kilometer in diameter, and as long as one phase would pass through it, the induced current (given some load) would be same as if the solenoid was not-quite-touching the phase wire. Things change, of course, when your solenoid's plane does not intersect the phase wire. I think I'll run a little experiment later today.