This power loss is given by P = I2R. Thus, given the overall transmitted power is the same, low-voltage, high-current transmissions will suffer a much greater power loss than high-voltage, low-current ones, given the practical range of conductor sizes.
Essentially, since we can use high-voltage for transmission and then convert it to low-voltage on the poles, we can take advantage of the greater efficiency achieved by using a higher voltage and therefore a lower current to transmit the same total power.
Human safety. AC at the same voltage / current is a lot less dangerous than DC. AC makes your muscles shake but DC makes them tense. If you grab DC you will just hold on tighter the more current you take.
Efficiency. DC loses more energy per foot / mile than AC.
Conversion capability. It's easy to convert AC from one voltage to another by running it through a coil and taking a tap off the other side. You can't do this with DC. Either you need a fancy transister circuit (with lots of heat an inefficiency, also difficult at higher currents) or you need to convert it to AC and then convert it and bring it back to DC
Power gets converted to DC anyhow to keep the UPS batteries charged. If the lights go out, the DC from the batteries is converted back to AC to go to the power supplies and back to DC inside each system.
No, it doesn't take as much power to keep the batteries charged as it would to run the center off DC, but that's not the point. Anyone with a large UPS already has a beefy AC/DC and DC/AC conversion system in place.
I would also assume one large converter / power supply would be more efficient for power and heat than hundreds (in my data center) or thousands (in a big one) of little power supplies. Any thoughts on that?
Cisco is a late player to this game, and they're still catching up. They bought a company to bring this technology into the Cisco brand, and they're still working on "cisco-izing" the product.
Last time I checked this only works with Cisco hardware in the wiring closets.
Other than that, does it yet come close to the capabilities of Bradford's Campus Manager? Any college trying to lock down their resnet probably used Campus Manager.
The problem, of course, is how to decide whether someone is "secure" or not without running a scan on that computer.
Just run a scan on them. Either a) they're your (IT's) computers, or (b) they signed an acceptable use policy, which says you might scan for vulnerabilities.
Ok, the article is light on technical details, but it seems that they are using guard pigs. Guard pigs aren't exactly shiny new. The Battalion has been using them since a long long time.
Apple's Password Service is the authentication database for Open Directory. All other services reference the Password Server database for authentcation services.
They don't really call it Password Server anymore, they just talk about it as a part of Open Directory.
Does it work with the iSight?
I've been trying to get it to work recently with Fedora Core 4 but dv1394-2.0-pre is currently lacking support and dv1394-1 won't compile with gcc 4. Such is the way of Linux, yet I still try.
Ya know, I'd love to, but I have too many web applications which just don't work with anything other than Internet Explorer on Windows.
Somebody needs to tell College Board, Packetshaper, APC, and others to abandon IE before I can abandon IE.
I can state that Apple does indeed take security seriously. Filesystem ACLs, seperation of priveliges, secure swap, encrypted home directories, and frequent security updated separated from OS updates are good clues that Apple seriously thinks about security features and security of features.
The article completely misses the importance if git.
Yes, Linus is a limited resource, and if he takes time to work on a development tool, kernel releases are delayed, but that doesn't mean overall kernel development has delayed overall.
But the importance of git should not be overlooked.
Linus and friends have been making a custom tool designed to fit their hands perfectly and accompany them in the way that they (the developers) work. In the long run, git will be a better tool for them because they designed it to meet the way they work instead of using an existing tool and changing how they work to match the functionality and nuances of that tool.
Look forward to more efficient development in the next year, that's what I say.
The rumor sites are saying Java 5 is on the way also, as a separate update. This way older applications have a better chance of working on an out-of-the-box Tiger install.
Slashdot Mirror
Well, I simplified it. Check out the wikipedia article for the whole story.
Essentially, since we can use high-voltage for transmission and then convert it to low-voltage on the poles, we can take advantage of the greater efficiency achieved by using a higher voltage and therefore a lower current to transmit the same total power.
Power gets converted to DC anyhow to keep the UPS batteries charged. If the lights go out, the DC from the batteries is converted back to AC to go to the power supplies and back to DC inside each system.
No, it doesn't take as much power to keep the batteries charged as it would to run the center off DC, but that's not the point. Anyone with a large UPS already has a beefy AC/DC and DC/AC conversion system in place.
I would also assume one large converter / power supply would be more efficient for power and heat than hundreds (in my data center) or thousands (in a big one) of little power supplies. Any thoughts on that?
Yep, they're real nice, but not all that new.
I've had 2 of them side-by-side on my desk since the beginning of August!
I heard it was the Japanese...
Check out Weather Wars
Cisco is a late player to this game, and they're still catching up. They bought a company to bring this technology into the Cisco brand, and they're still working on "cisco-izing" the product.
Last time I checked this only works with Cisco hardware in the wiring closets.
Other than that, does it yet come close to the capabilities of Bradford's Campus Manager? Any college trying to lock down their resnet probably used Campus Manager.
The problem, of course, is how to decide whether someone is "secure" or not without running a scan on that computer.
Just run a scan on them. Either a) they're your (IT's) computers, or (b) they signed an acceptable use policy, which says you might scan for vulnerabilities.
It's about time! That z990 under my desk just isn't fast enough :-)
This is no big deal. Snort will continue to be GPL and freely available to the world.
I'm more worried about the recent Nessus changes, have you heard about this?
Nessus License Change Announcement
Nessus 2 will continue to be free
Nessus 3 will be a free of charge, binary only release
Ok, the article is light on technical details, but it seems that they are using guard pigs. Guard pigs aren't exactly shiny new. The Battalion has been using them since a long long time.
Apple's Password Service is the authentication database for Open Directory. All other services reference the Password Server database for authentcation services.
They don't really call it Password Server anymore, they just talk about it as a part of Open Directory.
Great... yet another reason to upgrade hardware when planning for a Vista install.
Gotta add more cycles to the those brute-force attack teams!
that's libdc1394, not libdv1394. whee.
Does it work with the iSight? I've been trying to get it to work recently with Fedora Core 4 but dv1394-2.0-pre is currently lacking support and dv1394-1 won't compile with gcc 4. Such is the way of Linux, yet I still try.
There are, however, viruses that affect applications which run on Mac OSX. We run antivirus on our Macs because we use Microsoft Office.
Ya know, I'd love to, but I have too many web applications which just don't work with anything other than Internet Explorer on Windows. Somebody needs to tell College Board, Packetshaper, APC, and others to abandon IE before I can abandon IE.
Well, no, but I noticed it as soon as I submitted it. I got a laugh out of the unintended meaning...
Porting the existing drivers to this new acceleration architecture should be easy.
<sarchasm>
Except for NVidia!
</sarchasm>
I can state that Apple does indeed take security seriously. Filesystem ACLs, seperation of priveliges, secure swap, encrypted home directories, and frequent security updated separated from OS updates are good clues that Apple seriously thinks about security features and security of features.
The article completely misses the importance if git.
Yes, Linus is a limited resource, and if he takes time to work on a development tool, kernel releases are delayed, but that doesn't mean overall kernel development has delayed overall.
But the importance of git should not be overlooked.
Linus and friends have been making a custom tool designed to fit their hands perfectly and accompany them in the way that they (the developers) work. In the long run, git will be a better tool for them because they designed it to meet the way they work instead of using an existing tool and changing how they work to match the functionality and nuances of that tool.
Look forward to more efficient development in the next year, that's what I say.
Java 5 is not included with the operating system, but 1.4.2 is included.
Java 5 will be provided as a separate installer, so that folks can upgrade when they're ready.
does this mean I can tust my computer now?
:-(
we've had a growing apart since it started cheating on me and got a virus
git 'er done!
I don't follow this analogy...
The rumor sites are saying Java 5 is on the way also, as a separate update. This way older applications have a better chance of working on an out-of-the-box Tiger install.