"It's not very intuitive, but the contact patch is the same with narrow and wide tires. If the weight of the car and tire pressure remains the same, then also the contact area must be the same."
This is not necessarily so. You are also assuming similar construction.
It depends a lot on the rigidity of the tire, and tires made in this fashion are typically more rigid than your standard street tire. So the same pressure will typically have a smaller contact patch.
Almost forgot... all the famous cases having to do with computer-controlled cars. Many, many lawsuits. Relatively slow adoption. Mistrust leading up to the present day.
"You do realize that in an airport they can pretty much search whoever and whatever they want, with or without a dog or machine, right?"
Only international airports, for international flights.
Other than those, what they "can do" is pretty much Constitutionally limited, although I admit the Supreme Court has not seemed to feel very constrained by the Constitution in recent, past years.
"For a comparatively small number of people, who are at high risk, the legitimate applications are most salient. For the people presently at little or no risk, there isn't much room for improvement and there is fairly obvious room for trouble."
But there you go. For the vast majority of domestic cases, there is little to no legitimate justification. At least a properly-calibrated machine (presumably) has no bias.
"Yeah, who cares about bombs killing people!? This infringes on my right to secretly carry my lucky bag of ANFO with me wherever I go!"
Please show me where sniffer dogs have uncovered ANYBODY carrying explosives at airports during the years since 9/11. I can certainly point out a few cases where they didn't...
I say that because this kind of technology has been around for many years. But hair or otherwise, location by isotope has so far turned out to be a boondoggle.
For example, for years TV shows (and the FBI themselves) claimed that they could trace ammunition to the manufacturer by the particular isotopic composition of the lead in bullet fragments.
False. It just isn't reliable. They did it for years, and it just doesn't work. The better the technology got, the more unreliable it was shown to be. Lead formulations change; suppliers change; the very ore from which the lead is refined, varies even from the same mine. Convictions were overturned.
In some ways, it parallels the evolution of DNA as evidence: it is far, far less reliable than it was first made out to be. Not only is it ridiculously easily contaminated, it can be deliberately planted, even more easily.
"If having an anon call you out bothers you (I admit he was a bit obnoxious about it), you should include links in the original statement. Anyone could have said, "dogs are perfect" or "dogs are worthless" without any references."
Under a lot of circumstances I do that. But in cases where anybody can find the damned information themselves with a moment or even less on Google, I don't feel the need. I am not a library (or a paid librarian), to go look up information for any bozo's purposes at their whim.
When your tires are rolling, the friction in the direction they are rolling is far from zero, but it is vastly less (in normal road conditions) than from side-to-side. The "contact patch" of your tire is (relatively speaking) in a static position on the roadway, and so is under static friction. That is what keeps you going in the direction you point it.
When a tire is locked up, however, it is in dynamic friction. Dynamic friction is not only much lower than static friction, but since the tire is locked up, it no longer "cares" what direction it goes in, because the friction is exactly the same no matter what that direction is. Sliding is sliding, and the contact area is constant.
So if you are in a situation of rear-wheel lockup, but your front wheels are still rolling but braking, the rear of your car is going to "want" to overtake the front, and there is nothing at all keeping the rear from swinging out sideways and doing so, if there is any deviation at all from a perfect straight line. Not A Good Thing.
You can do this experiment with a small model car. Lock up the front wheels but not the back, and give it a good shove forward on a relatively smooth surface. Chances are, it will keep going more-or-less forward. Then free the front wheels and lock the back, and give it the same kind of shove. It will spin all over the place.
That is why for many years (before ABS), manufacturers would put disk brakes on the front but old-style drum brakes on the back. Because IF you are going to get a lockup, you want it to be your front wheels, not the rear.
Air bags, antilock (ABS) brakes (note: that is a report from back in '98), steering wheel locks (too old to find easily on Google)... etc. Just about everything that has had to do with removal of operational control from the driver.
" I've got a set of skinny Blizzaks that I use for winter driving, and the combination makes the E36 the most stable and predictable car I've ever driven on snow and ice."
I live in an area that often has very snowy winters, and trying to convince people to use narrow tires in the winter is like talking to a brick wall. They want to put monster tires on their trucks, for example, and try to claim that the big "contact patch" will solve all their problems.
But I have seen the difference with my own eyes. Listen to parent, folks. If you drive on snow & ice, get narrow tires. It might just save your butt.
"NFC's more fundamental problem though is adoption, which is the same problem with this Apple standard."
I understand what you are saying but I disagree. Adoption would cause problems. Very serious privacy and financial problems.
Remember, NFC isn't even relative "passibe" like RFID. The signal power might be low, but it actively transmits. If you can use cheap, portable, concealable gadgets to sniff NFC info from a distance, what about the people who are willing to spend money and install giant antennas on just the other side of the wall? (Like Chris what's-his-name who sniffed "secure" passport RFID info from people from in his car 30 feet away?)
Here's another. Though not an independent study, it did evaluate actual success rates according to the courts' own records and found only a 44% success rate. And that was the average. For one minority, the true-positive rate was clear down at 27%. (Can you say "cues from handlers"? Sure. I knew you could.)
You can't just argue that it's "the best". It has to be good enough. Not only that, but the huge potential for intentional cuing of the animals is seldom considered.
"That it is better 100 guilty Persons should escape than that one innocent Person should suffer, is a Maxim that has been long and generally approved." -- Benjamin Franklin, letter to Benjamin Vaughan, March 14, 1785.
You are once again (VERY rudely, by Slashdot standards) being completely off-topic again, you once again have waited days or weeks to make arguments that I have been done with for a while and are completely off my topic list by now. If you really think I am going to go back and dig through all those long-past comments in order to argue with you, you are mistaken.
That is ONE of the reasons I have called you rude and obtuse.
But the one argument I will make is this: you ALSO insist on taking my comments out of context, and insisting that I meant something other than I did. Take the one about vectors, for example. I mentioned that it had direction (with which you apparently agreed), then objected to me mentioning the direction in which it was "directed".
This is a completely ridiculous splitting of hairs. By "directed" I simply meant it had direction. I was not proposing that it was being "directed" by anything.
" Instead, energy is removed from the vacuum itself."
And just what is it that makes you think I was arguing with anybody about that point?
Nevertheless, as I pointed out, depending on what theory you choose to follow, the positive energy density of the vacuum is anywhere from 10^-9 joules/m^3, to 10^119 joules/m^3. Anything in that range is still significantly positive.
My point was that depending on the way you do the math, sure you CAN show negative energy... but it is far from necessary. There are just as valid methods of caculation that show it as merely an absence of the positive energy elsewhere. That was all I was trying to say.
Anything else is hair-splitting on your part. YOU may not think so, but you have continually insisted on taking me too literally and picking my comments apart, then stalking me in other forums (and I suspect that you have tried to do it elsewhere, as well). And launch into this great diatribe about how wrong I am, in a situation in which you know damned well I am not interested in taking the time and effort to defend myself.
Go the fuck away, and leave me alone. Do you understand THAT? Or do I need to explain THOSE words to you, too?
"We can't use dogs to spy on everybody, everyplace, all the time."
You wouldn't want to anyway. In blind studies, drug- and explosive-sniffing dogs actually have a pretty terrible track record. A literally unacceptable percentage of false positives, for example.
Turned out, the dogs were responding to very subtle cues from their handlers, rather than their own senses. Which renders them completely inappropriate for law-enforcement use.
"Apple probably will have a dating service app bundled in . .."
There has been a device on the market, from Japan, for some years now. I don't remember what it's called. You can code in your personal tastes... perhaps you have particular dating preferences, say tall brunettes for example. Or even a fetish. When the device detects someone with similar coded characteristics or preferences, the devices beep and guide the people to each other.
I see no reason a similar app could not be developed for smart phones.
"So will Apple try to licence this technology to other mobile manufacturers, or will it forever remain on the shelf, never attaining sufficient popularity for POS vendors to support it?"
Who cares? I'm not trying to troll here, but the fact is that NFC was largely busted almost before it came off the shelf (researchers able to covertly read confidential info from mobile NFC devices from several feet away).
Unless technology changes significantly and soon, making financial transactions via radio is just plain a bad idea. You want to exchange E-cards? Fine. You can already do that via infrared or wifi or bluetooth. You don't need NFC (or a similar device or protocol) to do it.
Terrible law. Once you start making it illegal to "cause offense" to anybody, you have effectively shut down any pretense to freedom of speech.
In the U.S., "offensive" speech is particularly protected by our 1st Amendment, according to the Supreme Court, for the simple reason that non-offensive speech does not need protection.
Slashdot Mirror
"It's not very intuitive, but the contact patch is the same with narrow and wide tires. If the weight of the car and tire pressure remains the same, then also the contact area must be the same."
This is not necessarily so. You are also assuming similar construction.
It depends a lot on the rigidity of the tire, and tires made in this fashion are typically more rigid than your standard street tire. So the same pressure will typically have a smaller contact patch.
"Who says this is only going to be used in American airports?"
I wasn't. *I* was responding only to GP, and asking where that cheapness and reliability actually is.
Almost forgot... all the famous cases having to do with computer-controlled cars. Many, many lawsuits. Relatively slow adoption. Mistrust leading up to the present day.
"You do realize that in an airport they can pretty much search whoever and whatever they want, with or without a dog or machine, right?"
Only international airports, for international flights.
Other than those, what they "can do" is pretty much Constitutionally limited, although I admit the Supreme Court has not seemed to feel very constrained by the Constitution in recent, past years.
"You assume the swab is then used in a mass spectrometer. Putting the swab in a precursor that changes color when it detects something works too."
About as well as a dog. Please list for me the precursors for the 200 or so common explosives used today.
"For a comparatively small number of people, who are at high risk, the legitimate applications are most salient. For the people presently at little or no risk, there isn't much room for improvement and there is fairly obvious room for trouble."
But there you go. For the vast majority of domestic cases, there is little to no legitimate justification. At least a properly-calibrated machine (presumably) has no bias.
"Yeah, who cares about bombs killing people!? This infringes on my right to secretly carry my lucky bag of ANFO with me wherever I go!"
Please show me where sniffer dogs have uncovered ANYBODY carrying explosives at airports during the years since 9/11. I can certainly point out a few cases where they didn't...
I say that because this kind of technology has been around for many years. But hair or otherwise, location by isotope has so far turned out to be a boondoggle.
For example, for years TV shows (and the FBI themselves) claimed that they could trace ammunition to the manufacturer by the particular isotopic composition of the lead in bullet fragments.
False. It just isn't reliable. They did it for years, and it just doesn't work. The better the technology got, the more unreliable it was shown to be. Lead formulations change; suppliers change; the very ore from which the lead is refined, varies even from the same mine. Convictions were overturned.
In some ways, it parallels the evolution of DNA as evidence: it is far, far less reliable than it was first made out to be. Not only is it ridiculously easily contaminated, it can be deliberately planted, even more easily.
"If having an anon call you out bothers you (I admit he was a bit obnoxious about it), you should include links in the original statement. Anyone could have said, "dogs are perfect" or "dogs are worthless" without any references."
Under a lot of circumstances I do that. But in cases where anybody can find the damned information themselves with a moment or even less on Google, I don't feel the need. I am not a library (or a paid librarian), to go look up information for any bozo's purposes at their whim.
This.
When your tires are rolling, the friction in the direction they are rolling is far from zero, but it is vastly less (in normal road conditions) than from side-to-side. The "contact patch" of your tire is (relatively speaking) in a static position on the roadway, and so is under static friction. That is what keeps you going in the direction you point it.
When a tire is locked up, however, it is in dynamic friction. Dynamic friction is not only much lower than static friction, but since the tire is locked up, it no longer "cares" what direction it goes in, because the friction is exactly the same no matter what that direction is. Sliding is sliding, and the contact area is constant.
So if you are in a situation of rear-wheel lockup, but your front wheels are still rolling but braking, the rear of your car is going to "want" to overtake the front, and there is nothing at all keeping the rear from swinging out sideways and doing so, if there is any deviation at all from a perfect straight line. Not A Good Thing.
You can do this experiment with a small model car. Lock up the front wheels but not the back, and give it a good shove forward on a relatively smooth surface. Chances are, it will keep going more-or-less forward. Then free the front wheels and lock the back, and give it the same kind of shove. It will spin all over the place.
That is why for many years (before ABS), manufacturers would put disk brakes on the front but old-style drum brakes on the back. Because IF you are going to get a lockup, you want it to be your front wheels, not the rear.
Air bags, antilock (ABS) brakes (note: that is a report from back in '98), steering wheel locks (too old to find easily on Google)... etc. Just about everything that has had to do with removal of operational control from the driver.
" I've got a set of skinny Blizzaks that I use for winter driving, and the combination makes the E36 the most stable and predictable car I've ever driven on snow and ice."
I live in an area that often has very snowy winters, and trying to convince people to use narrow tires in the winter is like talking to a brick wall. They want to put monster tires on their trucks, for example, and try to claim that the big "contact patch" will solve all their problems.
But I have seen the difference with my own eyes. Listen to parent, folks. If you drive on snow & ice, get narrow tires. It might just save your butt.
"I hope that there will be plenty of logs, just in case that when your car avoids a dog and kills a kid you can go to cort and blame Nissan for it"
You nailed it. Because that's the typical history of this kind of technology:
1. It is introduced.
2. Somebody sues on the grounds that it caused an accident, rather than avoiding one.
3. It is taken off the market.
4. It is gradually improved, and finds its way back into the market. Fairly typical time frame: 10 years.
s/relative passibe/relatively passive
meh.
"NFC's more fundamental problem though is adoption, which is the same problem with this Apple standard."
I understand what you are saying but I disagree. Adoption would cause problems. Very serious privacy and financial problems.
Remember, NFC isn't even relative "passibe" like RFID. The signal power might be low, but it actively transmits. If you can use cheap, portable, concealable gadgets to sniff NFC info from a distance, what about the people who are willing to spend money and install giant antennas on just the other side of the wall? (Like Chris what's-his-name who sniffed "secure" passport RFID info from people from in his car 30 feet away?)
That first link above didn't show up. It is here.
Here's another. Though not an independent study, it did evaluate actual success rates according to the courts' own records and found only a 44% success rate. And that was the average. For one minority, the true-positive rate was clear down at 27%. (Can you say "cues from handlers"? Sure. I knew you could.)
Also, they are probably not the best things we have. And even if they were, that "best" is pretty obviously not good enough.
You can't just argue that it's "the best". It has to be good enough. Not only that, but the huge potential for intentional cuing of the animals is seldom considered.
"That it is better 100 guilty Persons should escape than that one innocent Person should suffer, is a Maxim that has been long and generally approved." -- Benjamin Franklin, letter to Benjamin Vaughan, March 14, 1785.
"Not to mention the probable fact that the dogs are most likely smarter than the average TSA employee."
Now THIS one needs modding up.
"Please link to proof of your "literally unacceptable percentage of false positives" for properly trained canines and handlers."
Easily done.
It amazes me how many people are so ready to call "bullshit" without taking 10 goddamned seconds on Google to check their facts.
If you think that is the only such study, you are mistaken. Google it dude. Learn something.
That is ONE of the reasons I have called you rude and obtuse.
But the one argument I will make is this: you ALSO insist on taking my comments out of context, and insisting that I meant something other than I did. Take the one about vectors, for example. I mentioned that it had direction (with which you apparently agreed), then objected to me mentioning the direction in which it was "directed".
This is a completely ridiculous splitting of hairs. By "directed" I simply meant it had direction. I was not proposing that it was being "directed" by anything.
" Instead, energy is removed from the vacuum itself."
And just what is it that makes you think I was arguing with anybody about that point?
Nevertheless, as I pointed out, depending on what theory you choose to follow, the positive energy density of the vacuum is anywhere from 10^-9 joules/m^3, to 10^119 joules/m^3. Anything in that range is still significantly positive.
My point was that depending on the way you do the math, sure you CAN show negative energy... but it is far from necessary. There are just as valid methods of caculation that show it as merely an absence of the positive energy elsewhere. That was all I was trying to say.
Anything else is hair-splitting on your part. YOU may not think so, but you have continually insisted on taking me too literally and picking my comments apart, then stalking me in other forums (and I suspect that you have tried to do it elsewhere, as well). And launch into this great diatribe about how wrong I am, in a situation in which you know damned well I am not interested in taking the time and effort to defend myself.
Go the fuck away, and leave me alone. Do you understand THAT? Or do I need to explain THOSE words to you, too?
"We can't use dogs to spy on everybody, everyplace, all the time."
You wouldn't want to anyway. In blind studies, drug- and explosive-sniffing dogs actually have a pretty terrible track record. A literally unacceptable percentage of false positives, for example.
Turned out, the dogs were responding to very subtle cues from their handlers, rather than their own senses. Which renders them completely inappropriate for law-enforcement use.
"Apple probably will have a dating service app bundled in . . ."
There has been a device on the market, from Japan, for some years now. I don't remember what it's called. You can code in your personal tastes... perhaps you have particular dating preferences, say tall brunettes for example. Or even a fetish. When the device detects someone with similar coded characteristics or preferences, the devices beep and guide the people to each other.
I see no reason a similar app could not be developed for smart phones.
"So will Apple try to licence this technology to other mobile manufacturers, or will it forever remain on the shelf, never attaining sufficient popularity for POS vendors to support it?"
Who cares? I'm not trying to troll here, but the fact is that NFC was largely busted almost before it came off the shelf (researchers able to covertly read confidential info from mobile NFC devices from several feet away).
Unless technology changes significantly and soon, making financial transactions via radio is just plain a bad idea. You want to exchange E-cards? Fine. You can already do that via infrared or wifi or bluetooth. You don't need NFC (or a similar device or protocol) to do it.
Terrible law. Once you start making it illegal to "cause offense" to anybody, you have effectively shut down any pretense to freedom of speech.
In the U.S., "offensive" speech is particularly protected by our 1st Amendment, according to the Supreme Court, for the simple reason that non-offensive speech does not need protection.
I tried the Boxee online service (sans box) for a while. It had the worst software and interface imaginable.
Weird controls, slow and unresponsive, hard to find needed functions, etc.
If my experience with Boxee online is any indication, there is no way I'd be buying hardware plus the associated software from those people.