Use MD5 or some other relatively strong checksum (CRC-32) too, just to be _absolutely_ sure that you didn't get any errors. It's a paranoia indulgence though if you are using TCP and rsync.
So that's $1.00 per square foot to pave a road with an OIL based substance which has to withstand repeated use by vehicles of around 1 1/2 to 20 tons on a regular basis for YEARS.
Let's see, is oil more expensive than it used to be, I wonder...
Think about all the equipment and time that goes into paving a road and moving all of that many tons of asphalt (which is almost certainly being shipped from a long way off, especially in a rural area).
Yes, there is corruption, but do you really believe it's building the price out by 50% ? I seriously doubt it.
Maybe some civil engineer could comment.
We have too many roads to maintain, that's the problem.
As many on these hallowed pages have pointed out, the focus needs to be on how to program, not necessarily the language.
As for those who think that languages like Python are too slow, they are being too simplistic.
Writing an LU factorization routine in Python for real world use is silly.
Writing such a routine in Python for educational reasons is perfectly fine.
And using such a routine for real work will involve calling a LAPACK routine _from_ Python, and will work great until the problem size isn't doesn't get too large.
So numerical work in Python or similar is perfectly fine, just as long as you use the right tool for the job.
So back to that FORTRAN thing... Why not ? Ultimately it depends. I'd say that other languages _are_ more suitable unless the student is going on to a life of hard-core number crunching. Dedicated simulation tools and programs like Mathematica and MATLAB are really what people use for everyday work.
You make an assumption that all of that lighting increases security. This really hasn't been proven. We'll pretend that it does. How about motion detectors ? A light that suddenly comes on when it _should not_ be on is much more of a deterrent.
Should I give you the anecdotal evidence of cars getting broken into while sitting _under_ a street light ? Nobody's watching at 3am - that's the problem.
Lighting fixtures are sh*t in this modern era. There has even been a resurgence in stupid globes which light up in all directions. Idiotic.
So the complaint is not so much of the tech which is causing this problem so much as the stupid ways in which we waste energy lighting up the night sky.
I know it can be convenient, but I think it's just crazy to let anyone directly charge your CC or worse yet, your bank account.
The era of buggy software which can make enormous mistakes quickly, hacked software which is out to get you, and corporate overlords who look at their customers as the enemy, makes it far to risky to grant them such access.
I won't do it.
Even if it's a CC and you can get it fixed, it's going to be a hassle.
Realistically the SNR of cable is very high. The bigger problem is reflections and impedance mismatches due to the high frequency of the data. As others have pointed out you can (as Gb does) use multiple pairs of wires.
Even at 10 bits/s/Hz on 4 pairs of wire, you are talking 25GHz of bandwidth. At those frequencies RF effects, i.e. mismatches are very important and will require very high quality connections and very high quality cable.
Coax should be used at 25GHz, and small diameter coax, not twisted pair.
There is also the problem of the electronics required to convert a 1 Tb/s data stream into some sort of parallel data stream for the compute blocks. Non-trivial.
I say toss the wire and work on more economical ways to connect fiber, so that I can run fiber at home.
This growing trend of announcing lab discoveries which _might_ hold commercial promise _sometime_ in the future, _maybe_, are really kind of annoying.
What do these accomplish ? Do they show the people supplying the research $ that something is being accomplished and that the researches aren't just sitting around the lab smoking fatties ?
Vaporware just doesn't do these "discovery" press releases enough justice.
Could some clever person out there think of a nice derogatory term for them ?
I'm pretty darn sure that shannon's theorem is about channel capacity. It _tells_ you how good you can be even when you use error correction. From wikipedia:
The theorem establishes Shannon's channel capacity for such a communication link, a bound on the maximum amount of error-free digital data (that is, information) that can be transmitted with a specified bandwidth in the presence of the noise interference, under the assumption that the signal power is bounded and the Gaussian noise process is characterized by a known power or power spectral densit
And, as another poster observed the particular article in question does not have anything to do with polarization. I was saying , and not very clearly, that they are simply taking advantage of multiple antennas, and it doesn't really matter what gee whiz thing they do with them, they are still going to get N*C bits/s/hz, where N is the number of antennas and C is the channel capacity for a single antenna.
Be careful that you do not confuse directionality of the antenna pattern (which gives you an apparent boost in power and therefor capacity) with some sort of magical capacity multiplier.
I like your example of the rod and the tube.
The biggest problem is that they don't actually provide any quantitative information.
However I agree with the original responder that it can sometimes be tricky defining what constitutes a channel.
Fix the bandwidth, fix the noise, fix the power. There is now a hard limit on your datarate. Don't care about coding, modulation format, or anything else in that 1 channel. All that stuff will effect the datarate which you _actually_ get and that number will be less than or equal to shannon's limit.
People only think they can play games with it to dupe potential investors.
A good question is, what constitutes a channel ?
Well channels have to be independent, that's why having more than 1 antenna works. Notice that in MIMO, 2 antennas on each side gives you 2 times the datarate (max) NOT 4 times. And it doesn't make a ripping bit of difference how you work the polarization on those antennas.
Added polarization on the _same_ antenna does _not_ count as an additional channel.
Polarization will ameliorate the effects of multipath, but it is most certainly not another channel.
LLW is anything that has been exposed to a reasonably low level of radiation
I think it's important to remember in all these discussions that being exposed to electromagnetic _radiation_ does _not_ make something radioactive.
It's exposure to neutrons which makes things radioactive. Alpha and beta exposure would probably make something radioactive as well, but, certainly in terms of fission reactors, it's primarily the neutron flux which is causing radioactive isotopes to form.
I thought that this entire line of doomerism had been dispensed with thanks to cosmic rays.
Since cosmic rays are striking the earth all the time, and a decent percentage of them have a much higher energy level than anything the LHC can produce, we should have already seen such a phenomena.
I thought the most important point in the FA was the shift in thinking which this kind of technology could one day produce:
But in the future, things will be built not from the top down, but the bottom up -- as in nature.
Nature has always pushed it's own tech forward via lots of small things working together. Lots of small things working together also creates redundancy.
Generally speaking you generate the signal (using an oscillator) then run it through an amplifier and filter before it goes through the antenna. Each of those stages consume power. The amplifier has an efficiency which means you get less power out in the signal than you put into the amplifier for operation, and the filter has loss.
The idea here is that the signal generation using the VCO (voltage controlled oscillator) is combined with the filtering and the antenna, in essence, as "one step".
However this is going to have a very narrow range of application. There are many reasons why a VCO needs buffering and isolation from the outside world. There are many cases, especially for complex modulation, where coupling the VCO like this more closely to the outside world will degrade it's performance (yes, even if you are using a PLL) to an extent that you wouldn't be able to make a working radio with it.
So for certain low power, low complexity applications this does help, but for anything which needs a "real" radio it won't do much good. It's really more of a packaging gee-whiz.
Slashdot Mirror
I spell carbon capture "c o a l s u b s i d y".
It's not going to work, it's just another way to subsidize coal companies, as if letting them blow the tops off of mountains wasn't enough.
Installing renewables local to where the power is needed is, of course, a great idea.
Use MD5 or some other relatively strong checksum (CRC-32) too, just to be _absolutely_ sure that you didn't get any errors. It's a paranoia indulgence though if you are using TCP and rsync.
Your point about the police being the correct authority is valid, but you know even the police can be a bunch of fuck-ups:
http://www.kvoa.com/global/story.asp?S=10544157
they can borrow mine. I never use it.
5280 ft * 22 ft wide = 116200 ft^2
So that's $1.00 per square foot to pave a road with an OIL based substance which has to withstand repeated use by vehicles of around 1 1/2 to 20 tons on a regular basis for YEARS.
Let's see, is oil more expensive than it used to be, I wonder...
Think about all the equipment and time that goes into paving a road and moving all of that many tons of asphalt (which is almost certainly being shipped from a long way off, especially in a rural area).
Yes, there is corruption, but do you really believe it's building the price out by 50% ? I seriously doubt it.
Maybe some civil engineer could comment.
We have too many roads to maintain, that's the problem.
"Even the guy who sent the Ask Slashdot only wanted advice on communicating with others."
Which is critically important if you are trying to organize a resistance movement.
As many on these hallowed pages have pointed out, the focus needs to be on how to program, not necessarily the language.
As for those who think that languages like Python are too slow, they are being too simplistic.
Writing an LU factorization routine in Python for real world use is silly.
Writing such a routine in Python for educational reasons is perfectly fine.
And using such a routine for real work will involve calling a LAPACK routine _from_ Python, and will
work great until the problem size isn't doesn't get too large.
So numerical work in Python or similar is perfectly fine, just as long as you use the right tool for the job.
So back to that FORTRAN thing... Why not ? Ultimately it depends. I'd say that other languages _are_ more suitable unless the student is going on to a life of hard-core number crunching. Dedicated simulation tools and programs like Mathematica and MATLAB are really what people use for everyday work.
You make an assumption that all of that lighting increases security. This really
hasn't been proven. We'll pretend that it does. How about motion detectors ? A light that suddenly comes on when it _should not_ be on is much more of a deterrent.
Should I give you the anecdotal evidence of cars getting broken into while sitting _under_ a street light ? Nobody's watching at 3am - that's the problem.
Lighting fixtures are sh*t in this modern era. There has even been a resurgence in stupid globes which light up in all directions. Idiotic.
So the complaint is not so much of the tech which is causing this problem so much as the stupid ways in which we waste energy lighting up the night sky.
I believe there was a storm in the area, a rather nasty one.
I know it can be convenient, but I think it's just crazy to let anyone directly charge your CC or worse yet, your bank account.
The era of buggy software which can make enormous mistakes quickly, hacked software which is out to get you, and corporate overlords who look at their customers as the enemy, makes it far to risky to grant them such access.
I won't do it.
Even if it's a CC and you can get it fixed, it's going to be a hassle.
Realistically the SNR of cable is very high. The bigger problem is reflections and impedance mismatches due to the high frequency of the data. As others have pointed out you can (as Gb does) use multiple pairs of wires.
Even at 10 bits/s/Hz on 4 pairs of wire, you are talking 25GHz of bandwidth. At those frequencies RF effects, i.e. mismatches are very important and will require very high quality connections and very high quality cable.
Coax should be used at 25GHz, and small diameter coax, not twisted pair.
There is also the problem of the electronics required to convert a 1 Tb/s data stream into some sort of parallel data stream for the compute blocks. Non-trivial.
I say toss the wire and work on more economical ways to connect fiber, so that I can run fiber at home.
its environmental impact isn't all that much worse than a lot of the "green" sources
That's an absurd statement.
You have obviously never heard of "mining" coal via mountain top removal.
Coal is awful on many levels, and the sooner we can get rid of it, the better.
I don't think big oil is the problem. I think it's more about keeping the corn farmers happy.
I don't think that keeping corn farmers happy is the problem. I think it's more about keeping big agri-business happy.
I guess this will get him banned from movie theaters, right ?
This growing trend of announcing lab discoveries which _might_ hold commercial promise _sometime_ in the future, _maybe_, are really kind of annoying.
What do these accomplish ? Do they show the people supplying the research $ that something is being accomplished and that the researches aren't just sitting around the lab smoking fatties ?
Vaporware just doesn't do these "discovery" press releases enough justice.
Could some clever person out there think of a nice derogatory term for them ?
Something to do with flying cars, maybe.
I'm pretty darn sure that shannon's theorem is about channel capacity. It _tells_ you how good you can be even when you use error correction. From wikipedia:
The theorem establishes Shannon's channel capacity for such a communication link, a bound on the maximum amount of error-free digital data (that is, information) that can be transmitted with a specified bandwidth in the presence of the noise interference, under the assumption that the signal power is bounded and the Gaussian noise process is characterized by a known power or power spectral densit
And, as another poster observed the particular article in question does not have anything to do with polarization. I was saying , and not very clearly, that they are simply taking advantage of multiple antennas, and it doesn't really matter what gee whiz thing they do with them, they are still going to get N*C bits/s/hz, where N is the number of antennas and C is the channel capacity for a single antenna.
Be careful that you do not confuse directionality of the antenna pattern (which gives you an apparent boost in power and therefor capacity) with some sort of magical capacity multiplier.
I like your example of the rod and the tube.
The biggest problem is that they don't actually provide any quantitative information.
However I agree with the original responder that it can sometimes be tricky defining what constitutes a channel.
123456890 = 2 * 5 * 17 * 751 * 967
Aaargh ! If only it had been prime.
Oh, wait just 1 more second.
1234567891 is prime :-)
You cannot play games with it.
Fix the bandwidth, fix the noise, fix the power. There is now a hard limit on your datarate. Don't care about coding, modulation format, or anything else in that 1 channel. All that stuff will effect the datarate which you _actually_ get and that number will be less than or equal to shannon's limit.
People only think they can play games with it to dupe potential investors.
A good question is, what constitutes a channel ?
Well channels have to be independent, that's why having more than 1 antenna works. Notice that in MIMO, 2 antennas on each side gives you 2 times the datarate (max) NOT 4 times. And it doesn't make a ripping bit of difference how you work the polarization on those antennas.
Added polarization on the _same_ antenna does _not_ count as an additional channel.
Polarization will ameliorate the effects of multipath, but it is most certainly not another channel.
It's not obvious to me what all the excitement is about.
"Huge" amounts of data as compared to what exactly ?
Whatever they are doing, it can't get past Shannon's theorem as a limit on the amount of information available for a given bandwidth.
This looks to me like it probably simply reduces to MIMO :
http://en.wikipedia.org/wiki/Multiple-input_multiple-output
Either way the capacity is limited to N * the capacity for one antenna (remember Shannon's law applies per channel).
So back to, what does this do exactly ?
boas, pythons, owls, hawks, monitor lizards, ...
I mean a python crawling in the ceiling eating mice while your coding python.
How cool would that be ?
LLW is anything that has been exposed to a reasonably low level of radiation
I think it's important to remember in all these discussions that being exposed to electromagnetic _radiation_ does _not_ make something radioactive.
It's exposure to neutrons which makes things radioactive. Alpha and beta exposure would probably make something radioactive as well, but, certainly in terms of fission reactors, it's primarily the neutron flux which is causing radioactive isotopes to form.
I have the home depot CFLs. My father has Sylvanias. Wattage is the same, and the sylvania's are MUCH brighter.
I thought that this entire line of doomerism had been dispensed with thanks to cosmic rays.
Since cosmic rays are striking the earth all the time, and a decent percentage of them have a much higher energy level than anything the LHC can produce, we should have already seen such a phenomena.
?
I thought the most important point in the FA was the shift in thinking which this kind of technology could one day produce:
But in the future, things will be built not from the top down, but the bottom up -- as in nature.
Nature has always pushed it's own tech forward via lots of small things working together. Lots of small things working together also creates redundancy.
Here's the idea:
Generally speaking you generate the signal (using an oscillator) then run it through an amplifier and filter before it goes through the antenna. Each of those stages consume power. The amplifier has an efficiency which means you get less power out in the signal than you put into the amplifier for operation, and the filter has loss.
The idea here is that the signal generation using the VCO (voltage controlled oscillator) is combined with the filtering and the antenna, in essence, as "one step".
However this is going to have a very narrow range of application. There are many reasons why a VCO needs buffering and isolation from the outside world. There are many cases, especially for complex modulation, where coupling the VCO like this more closely to the outside world will degrade it's performance (yes, even if you are using a PLL) to an extent that you wouldn't be able to make a working radio with it.
So for certain low power, low complexity applications this does help, but for anything which needs a "real" radio it won't do much good. It's really more of a packaging gee-whiz.