Actually, grand parent is right. Two parts with a MTBF of, say, an hour, used in the same system at the same time, sum to a MTBF of (slightly) less than 1 hour. Not directly, which would imply an MTBF of 1/2 an hour, but they sum.
Look at the space shuttle: No single part has an failure rate worse than once in 100K launches (IIRC; it may have been one in a million. It's in the design specs)*
Now, there are some odd million parts. WHOA! No, you don't get a failure every launch, but the failure rate is WAY higher than on in a million -- think the RFP/design specs 'required' a one in 10K chance of failure.
The reason for the discussion was based on some of the 'design requirements' floated about for the next-gen 'shuttle replacement' -- one of which was a 1 in a million chance of failure -- thus necessitating a piece-wise failure rate of around 1 in a billion.
And what in the world does the Monty Hall problem have to do with this?
Or just consider how they test for MTFB: Take 1000 parts. Run them until all of them die (not really for hard-drives, but this is how you do it for REALLY IMPORTANT things:~} ). Now plot the distribution and take the mean.
Cheers,
* yes, I am a rocket scientist, and this was discussed in classes I took years ago.
Regardless of Visa's (idiotic) advice, placing 'See Photo ID' on the back of your card is about a thousand times more likely to get a crook caught than having your sig. on the back.
Really simple, when you think about it: The crook doesn't look like you. But they have your card. And, if you signed it, your sig. So they go practice two or three times and, usually, thats going to be close enough for the clerks who actually check (pron: 'glance at') it (about 1 in 10?). Maybe 1 in a 10000 would of those who check would call the 'customer' on it, unless the sigs are WAY different. Or legible and spelled wrong or something. And you know how to get around that? Oh! Wear a finger brace! "Gee, I'm sorry I can't sign my name very well."
Now, if it says 'See Photo ID' (like all of mine, and I've NEVER been told to sign it), then, assuming the thief has your photo ID, he has to alter it or create their own. Not hard, but more work than they are going to want to do.
And, for reference, I get asked for my photo ID about 1 in 4 times that I use a card -- the higher the price the better the odds, in general.
So, what that means is that you, while following the 'rules' (advice, really, on that page; but stupid enough to be a Visa rule), are exposing yourself more to theft of funds than I, who am *not* following the 'rules'. Who's the fool?
Personally, I think the guy who was outraged was right, not you -- regardless of bad advice from corporate.
Dude, that's Roxio crapware that is built in... it is most 100% certainly *NOT* excellent burning software. Its bloody horrible actually. 'Progress' dialog boxes that don't actually tell you they are done (always says 'cancel'), dozens of coasters, made on demand....
Yech. Horrible memories. Uni left that on there. Ugh.
I agree, it shouldn't be an issue. Just tossing crap out. I don't know how many photons of high enough energy to be a 'dangerous' would be issued per second, and was kind of hoping someone else would do the math for me;~)
Not high on my list of worries, just fun to consider possible solutions to difficult problems.
For more fun, we could toss in wave interferometry! Wouldn't mean anything, but we can play;~)
I am going to drive to the store now, even though we know for a fact that 45 thousand people died in the US last year in auto-related accidents.
Thanks -- no mod points, but that was enlightening.
Also makes sense from the digital signals causing more damage at lower power levels than does analog signals at higher powers. Perhaps more well-defined wave form that is more efficient at [re]orienting the DNA strand?
Or hell, maybe just jaring it during recombination, knocking it off kilter, or twisting it when it is unzipped.
Just visualizing the tiny bit that I am capable of:~)
If anyone wants to take issue with my statements above, for gods sake educate me. I want to know. I already know I am not a biologist;~)
The energy per photon is just too low to break covalent bonds[...]
The *mean* energy is too low; however we are talking about an energy distribution: No antenna is perfect, nor is any transmitter perfect. Thus there will be some fairly high energy photons at some predictable -- and non-zero -- rate.
Don't know how much, don't know if it is statistically significant. Just occured to me.
The point is that "microwaves damage DNA" is an extraordinary claim that requires extraordinary evidence. "Some studies support it and some do not" simply doesn't qualify
Exactly. And don't you find it a bit worrysome that the companies are putting extensive restrictions on research grants, and the the US is no longer putting untethered money into the hat?
I would like to see a few studies I can trust. The crap coming from the Cell phone industry is FUD. 'Cell phones operate at different frequencies'. WTF? By like a few hundred Hz. That is a straw man. If they had legit counter arguments I would think that they would use them. Not wage a war of credibility.
I personally don't see the mechanisim for damage, either. My understanding of EMF interactions on bio organisms is very low. I see respected scientists in their fields saying 'we need more research'. So I say 'Ah... I'll go with More Research for 1000, Alex'.
Given the POTENTIAL here (guess: pretty much everyone on the planet that HAS a phone will be using a cell phone in 30 years), I think its worth a good 50 million for a first round of studies. First round. Look at those and ONLY those results, and then dump an intelligent amount into a second round -- maybe another 50, maybe 200, maybe 10. All in all, cheaper than even a few hundred tumor treatments.
Is it unfair to the share holders? I don't think so in the least.
Shareholders have a responsibility to look into the operations of a company. If the shareholders weren't such money-grubbing pricks the world wouldn't have these 'CEO xx is getting paid so much money boo hoo' problems.... Because the companies that did that would have no shareholders, and thus, no money.
Not unfair at all. Perfectly fair, really. It is the shareholders that direct public companies.
Thought experiment: If Intel hired Carly tomorrow, what indicator would be used to fire her on monday? You got it! The 10% drop in stock value!
If I run anything less than about 1.5GB RAM w/V-Mem off I run into them-pesky out-of-memory errors on some midrange linear algebra problems I run. I *Always* run into them on the large models. So the only time I bother to enable v-mem is when I am running the huge models.
With 2GB of RAM and no V-mam I don't have any problems, and that is running MySQL, Apache, Tomcat, and Crystal reports servers.... And World of Warcraft on occasion;~)
The 'legitimate' use of the machine is GIS mapping software, and some fun and unrelated mathmatical modeling.
Oh yea, and that is on a nForce4 board with a single 6800GT. So this really is on-topic, honest;~)
Your replies weren't impolite per-say, just annoying. I intensly dislike people who don't do their own math. Even with your assumptions, which are valid, my point is not invalid: You wouold need a many inches thick cable to charge a car that fast.
You failed to do 2 seconds worth of math to show that even in my most optimistic case (500V system, 10min charge) your 60% difference plus your comment about 300 amps in a 1/2" wire only prove my point: even if I am off by a factor of 10, the system would need at minimum an inch thick cable, or around 3 pair of 1/2" cables. Then you said I was wrong.
When you respond, pay attention to the actual point; you attacked the best case then acted as if it meant something. It didn't. Be constructive. You're entire focus was trying to prove me wrong. You simply can't do that. Why? Because I wasn't trying to be right! I was tossing out numbers with the obvious first word of ASSUME at the beginning of all the math.
You COULD have said 'I disagree with your assumptions' and then proceded to show your own, and work through the math. Then I, and many others, would have respected the post as informative and interesting. You didn't. So I didn't.
No, more like a foot or two. We're talking thousands of amps.
Assume 24 volt system, charging at 24 volts (you wouldn't want transformers etc onboard the car, they would be super heavy to handle this and would melt the car anyway):
I do wonder if you could charge the cells in series and discharge in parallel? Thus the system could perhaps be chaged at say 50kV, but the motors use 500V.
Regardless, if the batteries didn't charge at 99.9% efficiency the car would melt into the ground if you tried to charge them in 2 minutes.
Not a huge help. Basically the equation tells you what % of YOUR (the observer) 'time' (delta t) the person moving at velocity 'v' perceives -- e.g. the equation is used to calculate time dilation.
Same idea: E = mc^2 is incomplete. The full equation involves velocity via:
As to modems, I've wondered about that... My modem cables all run thru a heavy-duty surge unit; one hopes that helps
It doesn't. I did the math once on the Surge protectors I was selling at Sears -- the best one we had, with the $20K protection policy -- it could handle 2500 joule if I recall.
Assuming room temperature and nice even numbers (so 25 deg C), that could boil:
2500_J ~= 600 cal. 600cal/(75deg C) = 8
That is a whopping 8 ml of water.
How much energy you think is in that lightning bolt traveling down the phone line?
Modern surge protectors are to protect against in-home spikes -- buy them based on how much insurance you want, and ignore the power rating. But make sure they say that they cover lighting!
Or buy transformer / inductor based protection, which costs an assload more -- something like these
While much could be learned, if anyone said 'oh, method 'x' worked on Mars, so we are going to implement it here on Earth!' I would gleefully shoot them.
1/3 the surface gravity, little or no active plate techtonics etc etc etc. It would be like using spiders for testing Viagra -- "Hey look! All the legs got stiff!"
I did not say bypass garbage collection. So far as I know, that would be completely impossible. Could be wrong I suppose.
In large, memory intensive apps you need to HELP the GC --:: Don't create objects until you need them. This is a 'duh' a surprising number of people miss.:: Pause long enough for the GC to do its stuff. You won't run into this problem until you are doing some seriously heavy memory use. It is possible that your app can run in the default memory space, but the JVM isn't collecting disposed objects fast enough. If you are pegging the CPU and creating and discarding millions of objects, this may become a thorn in your side.:: Ensure that you don't maintain *ANY* references to objects you don't need any more, so that the GC doesn't have to 'think' to hard about 'is this okay to toss?' (think unlinked structures, simple case 3 or four objects that aren't visible to any other part of the code, but reference each other extensively).
There are other ways, tips and tricks etc. Using stringbuffers instead of strings for *any* string that might be used more than once, for example. 'Don't create it if you don't need it' can be harder than it sounds; you need to know what is happening in the background.
Slashdot Mirror
Actually, grand parent is right. Two parts with a MTBF of, say, an hour, used in the same system at the same time, sum to a MTBF of (slightly) less than 1 hour. Not directly, which would imply an MTBF of 1/2 an hour, but they sum.
Look at the space shuttle: No single part has an failure rate worse than once in 100K launches (IIRC; it may have been one in a million. It's in the design specs)*
Now, there are some odd million parts. WHOA! No, you don't get a failure every launch, but the failure rate is WAY higher than on in a million -- think the RFP/design specs 'required' a one in 10K chance of failure.
The reason for the discussion was based on some of the 'design requirements' floated about for the next-gen 'shuttle replacement' -- one of which was a 1 in a million chance of failure -- thus necessitating a piece-wise failure rate of around 1 in a billion.
And what in the world does the Monty Hall problem have to do with this?
Try: Math World
and:
NASA
And the most directly applicable:
Hotwire article
Or just consider how they test for MTFB: Take 1000 parts. Run them until all of them die (not really for hard-drives, but this is how you do it for REALLY IMPORTANT things:~} ). Now plot the distribution and take the mean.
Cheers,
* yes, I am a rocket scientist, and this was discussed in classes I took years ago.
But if you didn't have fellow employees, then you wouldn't need a door! :~D
Regardless of Visa's (idiotic) advice, placing 'See Photo ID' on the back of your card is about a thousand times more likely to get a crook caught than having your sig. on the back.
Really simple, when you think about it: The crook doesn't look like you. But they have your card. And, if you signed it, your sig. So they go practice two or three times and, usually, thats going to be close enough for the clerks who actually check (pron: 'glance at') it (about 1 in 10?). Maybe 1 in a 10000 would of those who check would call the 'customer' on it, unless the sigs are WAY different. Or legible and spelled wrong or something. And you know how to get around that? Oh! Wear a finger brace! "Gee, I'm sorry I can't sign my name very well."
Now, if it says 'See Photo ID' (like all of mine, and I've NEVER been told to sign it), then, assuming the thief has your photo ID, he has to alter it or create their own. Not hard, but more work than they are going to want to do.
And, for reference, I get asked for my photo ID about 1 in 4 times that I use a card -- the higher the price the better the odds, in general.
So, what that means is that you, while following the 'rules' (advice, really, on that page; but stupid enough to be a Visa rule), are exposing yourself more to theft of funds than I, who am *not* following the 'rules'. Who's the fool?
Personally, I think the guy who was outraged was right, not you -- regardless of bad advice from corporate.
Known
Hypothesized.
Significant difference with profound ramifications in this case.
Dude, that's Roxio crapware that is built in... it is most 100% certainly *NOT* excellent burning software. Its bloody horrible actually. 'Progress' dialog boxes that don't actually tell you they are done (always says 'cancel'), dozens of coasters, made on demand....
:~)
Yech. Horrible memories. Uni left that on there. Ugh.
Can't argue with the rest, as I rather agree
Cheers,
I agree, it shouldn't be an issue. Just tossing crap out. I don't know how many photons of high enough energy to be a 'dangerous' would be issued per second, and was kind of hoping someone else would do the math for me ;~)
;~)
Not high on my list of worries, just fun to consider possible solutions to difficult problems.
For more fun, we could toss in wave interferometry! Wouldn't mean anything, but we can play
I am going to drive to the store now, even though we know for a fact that 45 thousand people died in the US last year in auto-related accidents.
No I wasn't. I am saying that you don't have ONE SINGLE FREQUENCY being broadcast, you have a PEAK at that one freq.
You will have some number of photons leaving your antenna at 2, 3, 4, 5, etc times your 'desired' wavelength.
Hell, we have terms for this: its called 'Harmonics'.
I can see where the quoted sentence would be rather easy to misconstrue, should someone want to; however, it is correct.
Thanks -- no mod points, but that was enlightening.
:~)
;~)
Also makes sense from the digital signals causing more damage at lower power levels than does analog signals at higher powers. Perhaps more well-defined wave form that is more efficient at [re]orienting the DNA strand?
Or hell, maybe just jaring it during recombination, knocking it off kilter, or twisting it when it is unzipped.
Just visualizing the tiny bit that I am capable of
If anyone wants to take issue with my statements above, for gods sake educate me. I want to know. I already know I am not a biologist
Just realized something re:
The energy per photon is just too low to break covalent bonds[...]
The *mean* energy is too low; however we are talking about an energy distribution: No antenna is perfect, nor is any transmitter perfect. Thus there will be some fairly high energy photons at some predictable -- and non-zero -- rate.
Don't know how much, don't know if it is statistically significant. Just occured to me.
You do understand that an embryo is a far simpler organism than a full-grown human and a lot more vulnerable to such things, right?
So you admit that we are vulnerable?
See, the phrase 'A lot more...' implies that there is some base of vulnerability to build from, even if small.
So where is this baseline? How about we spend some money to find it?
Cheers,
The point is that "microwaves damage DNA" is an extraordinary claim that requires extraordinary evidence. "Some studies support it and some do not" simply doesn't qualify
Exactly. And don't you find it a bit worrysome that the companies are putting extensive restrictions on research grants, and the the US is no longer putting untethered money into the hat?
I would like to see a few studies I can trust. The crap coming from the Cell phone industry is FUD. 'Cell phones operate at different frequencies'. WTF? By like a few hundred Hz. That is a straw man. If they had legit counter arguments I would think that they would use them. Not wage a war of credibility.
I personally don't see the mechanisim for damage, either. My understanding of EMF interactions on bio organisms is very low. I see respected scientists in their fields saying 'we need more research'. So I say 'Ah... I'll go with More Research for 1000, Alex'.
Given the POTENTIAL here (guess: pretty much everyone on the planet that HAS a phone will be using a cell phone in 30 years), I think its worth a good 50 million for a first round of studies. First round. Look at those and ONLY those results, and then dump an intelligent amount into a second round -- maybe another 50, maybe 200, maybe 10. All in all, cheaper than even a few hundred tumor treatments.
But then you get a BlueTumor instead of a CellTumor ;~)
Is it unfair to the share holders? I don't think so in the least.
Shareholders have a responsibility to look into the operations of a company. If the shareholders weren't such money-grubbing pricks the world wouldn't have these 'CEO xx is getting paid so much money boo hoo' problems.... Because the companies that did that would have no shareholders, and thus, no money.
Not unfair at all. Perfectly fair, really. It is the shareholders that direct public companies.
Thought experiment: If Intel hired Carly tomorrow, what indicator would be used to fire her on monday? You got it! The 10% drop in stock value!
Cheers,
[smartass-mode]
;~)
;~)
;~)
They are called 'out of memory errors'
[/smartass-mode]
If I run anything less than about 1.5GB RAM w/V-Mem off I run into them-pesky out-of-memory errors on some midrange linear algebra problems I run. I *Always* run into them on the large models. So the only time I bother to enable v-mem is when I am running the huge models.
With 2GB of RAM and no V-mam I don't have any problems, and that is running MySQL, Apache, Tomcat, and Crystal reports servers.... And World of Warcraft on occasion
The 'legitimate' use of the machine is GIS mapping software, and some fun and unrelated mathmatical modeling.
Oh yea, and that is on a nForce4 board with a single 6800GT. So this really is on-topic, honest
Cheers.
My response was inappropriate, I do admit.
Your replies weren't impolite per-say, just annoying. I intensly dislike people who don't do their own math. Even with your assumptions, which are valid, my point is not invalid: You wouold need a many inches thick cable to charge a car that fast.
You failed to do 2 seconds worth of math to show that even in my most optimistic case (500V system, 10min charge) your 60% difference plus your comment about 300 amps in a 1/2" wire only prove my point: even if I am off by a factor of 10, the system would need at minimum an inch thick cable, or around 3 pair of 1/2" cables. Then you said I was wrong.
When you respond, pay attention to the actual point; you attacked the best case then acted as if it meant something. It didn't. Be constructive. You're entire focus was trying to prove me wrong. You simply can't do that. Why? Because I wasn't trying to be right! I was tossing out numbers with the obvious first word of ASSUME at the beginning of all the math.
You COULD have said 'I disagree with your assumptions' and then proceded to show your own, and work through the math. Then I, and many others, would have respected the post as informative and interesting. You didn't. So I didn't.
WTF? .6 * 8000 amp = 4800.
Do some math on your own or shut the hell up.
Obviously that was a fast calculation. Jesus christ man! No shit the calculations aren't 100% right!
No, more like a foot or two. We're talking thousands of amps.
/(120s) = 20.17E6 Watts
p eed.htm
Assume 24 volt system, charging at 24 volts (you wouldn't want transformers etc onboard the car, they would be super heavy to handle this and would melt the car anyway):
20 gallons of gas = 20*121 MJ/gal = 2420MJ
1J = 1W*1S
2min = 120 sec
2420E6 W*S
20.17E6W / 24V = 840,278 Amp
However, the Prius uses 500 volt motors, as I understand it (http://hybridcars.about.com/od/news/a/priuslands
500V:
40,333 Amp
500V and 10Min:
8067 Amp
I do wonder if you could charge the cells in series and discharge in parallel? Thus the system could perhaps be chaged at say 50kV, but the motors use 500V.
Regardless, if the batteries didn't charge at 99.9% efficiency the car would melt into the ground if you tried to charge them in 2 minutes.
Actually, thats a good point. Make it a policy to click on the ad. Every time. Do it.
The site has to pay ad revenue per-click, right? Not per purchase?
The USPS doesn't operate on taxpayer money, except in the sence that generally the people sending letters also happen to be taxpayers.
One more time: USPS is not tax supported.
Mass Sol = 1.99E30_kg
.000005)
Mass Star = 5.97E30_kg
And the relativistic mass of the star:
M' = m/(sqrt(1-(v/c)^2))
= m/(sqrt(1 - (670*10^3/c)^2))
= m/(sqrt(1 -
= m/.999998
= 5.9700149*10^30
So an extra 1.5E26kg -- about 25 Earths (Earth mass = 5.979E24 kg)
FUN!!!
http://scienceworld.wolfram.com/physics/SpecialRel ativity.html
Not a huge help. Basically the equation tells you what % of YOUR (the observer) 'time' (delta t) the person moving at velocity 'v' perceives -- e.g. the equation is used to calculate time dilation.
Same idea: E = mc^2 is incomplete. The full equation involves velocity via:
E = m*(gamma)*c^2* = m*c^2/(sqrt(1-(v/c)^2))
As to modems, I've wondered about that... My modem cables all run thru a heavy-duty surge unit; one hopes that helps
It doesn't. I did the math once on the Surge protectors I was selling at Sears -- the best one we had, with the $20K protection policy -- it could handle 2500 joule if I recall.
Assuming room temperature and nice even numbers (so 25 deg C), that could boil:
2500_J ~= 600 cal.
600cal/(75deg C) = 8
That is a whopping 8 ml of water.
How much energy you think is in that lightning bolt traveling down the phone line?
Modern surge protectors are to protect against in-home spikes -- buy them based on how much insurance you want, and ignore the power rating. But make sure they say that they cover lighting!
Or buy transformer / inductor based protection, which costs an assload more -- something like these
While much could be learned, if anyone said 'oh, method 'x' worked on Mars, so we are going to implement it here on Earth!' I would gleefully shoot them.
1/3 the surface gravity, little or no active plate techtonics etc etc etc. It would be like using spiders for testing Viagra -- "Hey look! All the legs got stiff!"
Surface gravity is also much higher.
It isn't strange at all. Just good code practice.
:: Don't create objects until you need them. This is a 'duh' a surprising number of people miss. :: Pause long enough for the GC to do its stuff. You won't run into this problem until you are doing some seriously heavy memory use. It is possible that your app can run in the default memory space, but the JVM isn't collecting disposed objects fast enough. If you are pegging the CPU and creating and discarding millions of objects, this may become a thorn in your side. :: Ensure that you don't maintain *ANY* references to objects you don't need any more, so that the GC doesn't have to 'think' to hard about 'is this okay to toss?' (think unlinked structures, simple case 3 or four objects that aren't visible to any other part of the code, but reference each other extensively).
I did not say bypass garbage collection. So far as I know, that would be completely impossible. Could be wrong I suppose.
In large, memory intensive apps you need to HELP the GC --
There are other ways, tips and tricks etc. Using stringbuffers instead of strings for *any* string that might be used more than once, for example. 'Don't create it if you don't need it' can be harder than it sounds; you need to know what is happening in the background.