You are correct that it takes smaller amount of charge to cause a bit flip, but the cell also receives less charge because it has less volume. Furthermore, because cosmic ray tracks have extremely high energy, their tracks have a very dense portion, surrounded by a less dense portion of the track. The likelihood that any individual cell will be hit by the most dense portion of the track is lower...if the threshold for the bit flip is higher than the less dense portion of the ion track, there will be fewer upsets per cell.
I just want to contradict one point you made: "in space, rad hardening is not optional".
That is incorrect.
Microprocessors (electronics in general also) have a wide variety of radiation response out of the box. For instance, the AMD K6 is known to be pretty bad for single event latch-up and not very usable. On the other hand, the PC603 actually is not to bad right off a commercial foundry line.
With this in mind, there are also a number of ways to mitigate radiation effects, including latch-up protection circuits, EDAC, redundancy, cold sparing, etc. These methods can remove the number of effects that propogate to the subsystem or system level.
Radiation hardening in many instances can also succeed in preventing effects from reaching the system level, but there are a number of penalties to pay. Schedule is often the biggest (as you know, many rad hard processors are very old), cost (this stuff isn't cheap since it is boutique), performance (many rad hard processors can't perform to the speed of their commercial brothers because of layout changes, extra resistance etc.), and also many times the required power and size can be affected.
Now we are presented with two paths: 1) radiation harden a processor, 2) measure the rad effects of a commercial processor and mitigate them with extra circuitry (which has its own extra liabilities in cost, power, size, but typically are much lower).
In some instances, rad hard is the right choice (in human flight missions, it tends to be a good choice, but not always), and in some commercial products with some workarounds are best.
Simplifying the issue to "rad hardening is not optional" is wrong...it is optional, but if you say "radiation effects must be dealt with", then I agree with you.
Almost all processor modern or old are vunerable to cosmic ray glitches. Modern electronics have not proven to necessarily be any more sensitive to radiation, but many "experts" would love for you to think so.
As someone who likes to review papers, I believe there are two _REALLY_ good reasons to do it:
1) Keep the crap out. A large number of papers submitted for publication are rehashes of old work, incorrect, incomplete, make bad assumptions, and/or make bad conclusions. To have these types of papers in the written record of the field can make it impossible for the good ideas to be heard and recognized.
I have seen the effects of incorrect papers published causing government agencies to spend extra millions of dollars on a non-existent problem and significantly reducing the scientific progress in the field. Never underestimate the problems that a poor paper can cause...if the idea in the paper is really good, it can always be published at a later date when the author gets their act together, but the moment it is in the written record, it can be accepted almost as fact (even in the face of contradictory evidence published in another journal that might not be easily found. A good argument for a comprehensive index).
2) To improve your own work. By reviewing and editing other people's work, you learn what is really good and what is really bad. You might dislike a portion of a paper and then realize that you sometimes write the same errors or type of poor writing. Or you might find in someone else's papers the best way to present your data in the future or the best way to explain some complex subject. Plus you get early access to data that you might find helpful in your own research.
Editing and reviewing papers is a teaching tool that is as valuable to the teacher as the student in many cases.
Here (warning, it is a big, 4 MB, file) are some homicide rate statistics that suggest that you could safely live in many places in the US, although there are a few scary places also.
Are we all sure that this phenomenon of children going berserk is recent?
Everyone seems to assume so, but I'm not to sure...
How many small town news stories like that would have spread far enough for you to hear about them back in 1900 or even in 1950? Not many...Most people only knew about things that happened in their small towns, particularly before the widespread use of telephones.
Now information is spread instanteously; I can fidn out about the latest school shooting within an hour of it happening. In 1950, you *might* hear about it the next day, you might not ever hear about it.
To say that we know what the cause of these things are, is to reduce an extremely complex problem down to an absurd solution. It could be guns, it could be bullying, but I don't think those are the answers. John's essay indicates that many of these people (I would guess this holds for similar past crimes) are mentally disturbed/ill.
The problem seems to me to lie in the parents, teachers, and friends who might realize that their son/daughter/student/friend is having problems and doesn't step in to help. It is a failure of that person's support network. There is one obvious solution to this problem:
Pay attention to the people around you and talk to them if you think they are having problems; counsel them; help them. If you don't help them, who will?
.
BTW, the lameness filter sucks, repetition of a few characters can cause a filter, but the trolls seem to get by just fine.
I agree that marketing and sales are very important. But some of those people seem to think they can do without the creative people and that just is not true.
I agree that it is large, but it should be 2*PI*R*(20 meters or whatever you want to call the lateral dimension)...GEO satellites are only found at one inclination ~0 degrees, so there really aren't satellite intersections and it is only a circumference worth of space...still big though.
I think you got it wrong buddy. We keep Sales people employed. If we didn't create products that you could sell what exactly would you sell?
I hate this attitude that infrastructure people (HR, managers, salesman) have where they think they are the company. Without a product, there is not a company. We need your help to make things good, but YOU need our help just to have a job.
Well I have a solution, put the light content as the default and if they want more give them a link. The light can always be the default, with links to "Click here, let us set a cookie that says you like big bandwidth hogging content from our site forever". Then on the default light content site, check the cookie and redirect to heavy content. Am I missing something?
The parent is quite right and I would like to add that most satellites do not contain an OS (too much potential for trouble), but if they do were already likely to contain a RTOS that is Unix-like. Nobody thinks about putting Windows or MacOS in orbit for satellites because why would a CPU that has no local users need a GUI for?
A lot of on-orbit satellites CPUs are running state machines, not really an OS...most thoughts about CPUs in space have been considering Lynx or Vx Works.
Ooops, didn't notice that the link I provided is already in the article. RTFA (read the fucking article), right?
This does not appear to highly classified, if they are putting out stuff like this and this article, the company is looking for many other uses for this software. Doesn't sound secret to me
Note also that GPS is merely a method for determining your position and as such even if "Evil people" have control over GPS, then the wrong signal still will not control anything...okay, some stuff, but very little is solely controlled by GPS.
Also, please note that this was merely the source code for the programs that allow communication with the GPS satellites, not access codes (not necessarily easy to determine) nor even the communication signal frequency(ies) (although that would probably be pretty easy to determine).
Is it me or is the HYPE here at Slashdot getting out of control?
But don't you see, your source and the use of YOUR program are already free.
I have no clue what MS has to do with any of this talk. People just seem to invoke the name to talk about anything bad that could happen. Please find some new evil to harp on.
You can ask, but it is not "FREE" at all. To call something free, it should be.
The GPL could best be described as a "barter" license. Your code for theirs. But don't call it free, because you are not donating anything, you are not contributing anything, you are selling something.
How 'bout:
Test the compatibility for before putting it into a release?
Not use it.
AFAIK, Microsoft (invoked above only to try and stir up advocacy from the legions of microsoft haters) has no control over any distribution or source tree related to Linux. ALSO, AFAIK, they still screen code and test it before it gets put into and release. There is NO way what you are describing can happen.
I am not a troll; I just think the GPL and all these licensing issues are a plague on software.
If the license says that you can copy the software for any purpose, it means it.
You are probably concerned about derivative works, but why should a derivative work be free? Cause you deserve it? But you didn't write the extra parts and you still have the old piece of software. I see no reason a license should ever talk about derivative works. It then becomes less "free".
Slashdot Mirror
You are correct that it takes smaller amount of charge to cause a bit flip, but the cell also receives less charge because it has less volume. Furthermore, because cosmic ray tracks have extremely high energy, their tracks have a very dense portion, surrounded by a less dense portion of the track. The likelihood that any individual cell will be hit by the most dense portion of the track is lower...if the threshold for the bit flip is higher than the less dense portion of the ion track, there will be fewer upsets per cell.
I just want to contradict one point you made: "in space, rad hardening is not optional".
That is incorrect.
Microprocessors (electronics in general also) have a wide variety of radiation response out of the box. For instance, the AMD K6 is known to be pretty bad for single event latch-up and not very usable. On the other hand, the PC603 actually is not to bad right off a commercial foundry line.
With this in mind, there are also a number of ways to mitigate radiation effects, including latch-up protection circuits, EDAC, redundancy, cold sparing, etc. These methods can remove the number of effects that propogate to the subsystem or system level.
Radiation hardening in many instances can also succeed in preventing effects from reaching the system level, but there are a number of penalties to pay. Schedule is often the biggest (as you know, many rad hard processors are very old), cost (this stuff isn't cheap since it is boutique), performance (many rad hard processors can't perform to the speed of their commercial brothers because of layout changes, extra resistance etc.), and also many times the required power and size can be affected.
Now we are presented with two paths: 1) radiation harden a processor, 2) measure the rad effects of a commercial processor and mitigate them with extra circuitry (which has its own extra liabilities in cost, power, size, but typically are much lower).
In some instances, rad hard is the right choice (in human flight missions, it tends to be a good choice, but not always), and in some commercial products with some workarounds are best.
Simplifying the issue to "rad hardening is not optional" is wrong...it is optional, but if you say "radiation effects must be dealt with", then I agree with you.
Almost all processor modern or old are vunerable to cosmic ray glitches. Modern electronics have not proven to necessarily be any more sensitive to radiation, but many "experts" would love for you to think so.
As someone who likes to review papers, I believe there are two _REALLY_ good reasons to do it:
1) Keep the crap out. A large number of papers submitted for publication are rehashes of old work, incorrect, incomplete, make bad assumptions, and/or make bad conclusions. To have these types of papers in the written record of the field can make it impossible for the good ideas to be heard and recognized.
I have seen the effects of incorrect papers published causing government agencies to spend extra millions of dollars on a non-existent problem and significantly reducing the scientific progress in the field. Never underestimate the problems that a poor paper can cause...if the idea in the paper is really good, it can always be published at a later date when the author gets their act together, but the moment it is in the written record, it can be accepted almost as fact (even in the face of contradictory evidence published in another journal that might not be easily found. A good argument for a comprehensive index).
2) To improve your own work. By reviewing and editing other people's work, you learn what is really good and what is really bad. You might dislike a portion of a paper and then realize that you sometimes write the same errors or type of poor writing. Or you might find in someone else's papers the best way to present your data in the future or the best way to explain some complex subject. Plus you get early access to data that you might find helpful in your own research.
Editing and reviewing papers is a teaching tool that is as valuable to the teacher as the student in many cases.
Sounds like Microsoft has a long term plan to help linux out....Screw its biggest customers and make them look for alternatives.
I guess the outlook for alternative OSs and office suites is VERY good.
Here (warning, it is a big, 4 MB, file) are some homicide rate statistics that suggest that you could safely live in many places in the US, although there are a few scary places also.
Are we all sure that this phenomenon of children going berserk is recent?
Everyone seems to assume so, but I'm not to sure...
How many small town news stories like that would have spread far enough for you to hear about them back in 1900 or even in 1950? Not many...Most people only knew about things that happened in their small towns, particularly before the widespread use of telephones.
Now information is spread instanteously; I can fidn out about the latest school shooting within an hour of it happening. In 1950, you *might* hear about it the next day, you might not ever hear about it.
To say that we know what the cause of these things are, is to reduce an extremely complex problem down to an absurd solution. It could be guns, it could be bullying, but I don't think those are the answers. John's essay indicates that many of these people (I would guess this holds for similar past crimes) are mentally disturbed/ill.
The problem seems to me to lie in the parents, teachers, and friends who might realize that their son/daughter/student/friend is having problems and doesn't step in to help. It is a failure of that person's support network. There is one obvious solution to this problem:
Pay attention to the people around you and talk to them if you think they are having problems; counsel them; help them. If you don't help them, who will?
.
BTW, the lameness filter sucks, repetition of a few characters can cause a filter, but the trolls seem to get by just fine.
I guess you were not really around when viruses were mostly spread by floppies? Was that really all that long ago?
I agree that marketing and sales are very important. But some of those people seem to think they can do without the creative people and that just is not true.
I agree that it is large, but it should be 2*PI*R*(20 meters or whatever you want to call the lateral dimension)...GEO satellites are only found at one inclination ~0 degrees, so there really aren't satellite intersections and it is only a circumference worth of space...still big though.
I think you got it wrong buddy. We keep Sales people employed. If we didn't create products that you could sell what exactly would you sell?
I hate this attitude that infrastructure people (HR, managers, salesman) have where they think they are the company. Without a product, there is not a company. We need your help to make things good, but YOU need our help just to have a job.
Well I have a solution, put the light content as the default and if they want more give them a link. The light can always be the default, with links to "Click here, let us set a cookie that says you like big bandwidth hogging content from our site forever". Then on the default light content site, check the cookie and redirect to heavy content. Am I missing something?
Almost no mail gets read by your congress person; a staffer reads the mail before it will ever meet a congress person's eyes
No one said anything about using Linux in mission critical Space Shuttle applications...the article specifically mentions satellites only.
The parent is quite right and I would like to add that most satellites do not contain an OS (too much potential for trouble), but if they do were already likely to contain a RTOS that is Unix-like. Nobody thinks about putting Windows or MacOS in orbit for satellites because why would a CPU that has no local users need a GUI for?
A lot of on-orbit satellites CPUs are running state machines, not really an OS...most thoughts about CPUs in space have been considering Lynx or Vx Works.
Is is really all that cheap, a Compact Flash card costs ~$30, add a PCMCIA adaptor and the spare parts. I'm not impressed
GPS is not typically used on board aircraft for altitude determination.
They typically broadcast local radio signals that aircraft use in addition to more traditional altimeters.
Ooops, didn't notice that the link I provided is already in the article. RTFA (read the fucking article), right?
This does not appear to highly classified, if they are putting out stuff like this and this article, the company is looking for many other uses for this software. Doesn't sound secret to me
So many of the comments on this article appear to be either off-topic or wrong.
For more information about the system itself, please see: http://biz.yahoo.com/prnews/001220/fl_exigent.html
Note also that GPS is merely a method for determining your position and as such even if "Evil people" have control over GPS, then the wrong signal still will not control anything...okay, some stuff, but very little is solely controlled by GPS.
Also, please note that this was merely the source code for the programs that allow communication with the GPS satellites, not access codes (not necessarily easy to determine) nor even the communication signal frequency(ies) (although that would probably be pretty easy to determine).
Is it me or is the HYPE here at Slashdot getting out of control?
But don't you see, your source and the use of YOUR program are already free.
I have no clue what MS has to do with any of this talk. People just seem to invoke the name to talk about anything bad that could happen. Please find some new evil to harp on.
You can ask, but it is not "FREE" at all. To call something free, it should be.
The GPL could best be described as a "barter" license. Your code for theirs. But don't call it free, because you are not donating anything, you are not contributing anything, you are selling something.
There is nothing you can do?
How 'bout:
Test the compatibility for before putting it into a release?
Not use it.
AFAIK, Microsoft (invoked above only to try and stir up advocacy from the legions of microsoft haters) has no control over any distribution or source tree related to Linux. ALSO, AFAIK, they still screen code and test it before it gets put into and release. There is NO way what you are describing can happen.
I am not a troll; I just think the GPL and all these licensing issues are a plague on software.
I also am not a fan of microsoft.
You can certaintly do that.
If the license says that you can copy the software for any purpose, it means it.
You are probably concerned about derivative works, but why should a derivative work be free? Cause you deserve it? But you didn't write the extra parts and you still have the old piece of software. I see no reason a license should ever talk about derivative works. It then becomes less "free".
In response to all the arguments above, why would you give the software away for free if you really wanted money for it?
If you want money for it, keep your source and charge for it, don't give your source away.