RFID and wireless smartcards use something called "Inductive Coupling" to transfer information from the card to the reader. What this means is that the antenna coils in the RFID and the reader create a loosely coupled transformer. When the RFID or smartcard wants to send information to the reader, it switches on/off a load connected to the antenna which changes the impedance of the whole system, including the impedance of the antenna on the reader. These changes in measured impedance are detected by the reader and interpretted according to whatever protocol is used.
Now, it's very possible for several antennas to be coupled. In fact, it is specifically allowed for by the standards (otherwise how could a reader talk to multiple RFIDs or smartcards at the same time?). However, since there is no wave shaping (or whatever) going on, things that would increase sensitivity in a traditional radio frequency setup (like a pringles can or dish receiver) won't help. What matters is the distance between the antennas and the area inside the coils multiplied by the number of coils in each respective antenna.
The most important thing to understand is that since each antenna is coupled with each other antenna, there is no such thing as a completely passive antenna. Each antenna added changes the measured impedance of all other coupled antennas and, as such, can be detected when entering or exiting the coupled system (I don't know of any hardware that attempts to detect entering/exiting antennas).
So, is it impossible to read from a distance? No, but it is harder than with normal RF and has much shorter range. Is it impossible to eavesdrop another communication? No, but again, it has much shorter range and, as such, is more difficult.
As far as I know, there are no passive RFID readers, so his comment is correct. The reader has to be powerful enough to energize the RFID tag at the distance. If it can do that, since the RFID chip uses inductive coupling (as opposed to being a transmitter itself), then the reader is automatically sensitive enough to read it.
Now that's simply not true. Every distro has install docs that very clearly tell you how to install the distro and explains the options available to you. Even install-intensive distros like Gentoo can be installed without ever looking at anything other than the install doc.
It's true that if you know nothing about Linux that the install docs might not make much sense to you, but they'll get you to a perfectly functioning system even if you just follow the directions without any understanding at all.
Ubuntu also boasts one of the largest community bases of all the Linux distributions, called the Ubuntu Forums, which contain more than 67,000 unique registered users.
Hmm...the Gentoo forums have over 111,000 unique registered users.
As if unique forum name count was a meaningful metric of anything.
Dell Laptops have been crap for years according to every Dell laptop owner I've ever known
My work laptop is a Dell and it's a fine machine with the following exceptions: 1. Crappiest keyboard I've ever had on a laptop 2. Broadcom wireless chipset has no native Linux support. It works with ndiswrapper, but I don't trust it.
...combined with the relatively short life expectancy of a computer...
Out of curiosity, how long do you think the life expectancy of a modern computer is?
There was a time when it seemed like you needed to upgrade every 2 years or so just to have a fast enough computer for the current software, but I think we got past that 5 or 6 years ago. I haven't upgraded my persomal machine in 5 years (at half a gig, it's a little tight memory-wise compared to modern machines, but the 1.2GHz AMD chip has no problem with current software) and my laptop is about the same age. At work I have much newer machines, but I don't really notice the speed difference except during compiles.
If you're going to give someone access to text editing but you don't trust them with shell access, compile vi/vim/[editor of choice] without access to shell escapes. It's a compile option for vim and, I would suspect, others. In fact, most new editors probably don't even have a way to escape to a shell.
You can configure sudo not to allow people to 'sudo su' or 'sudo bash'.
If you bother to read the sudoers manpage, you'll see that there's a lot you can do with sudo without necessarily giving up complete control of the root user.
The reason we run Gentoo at work is because it takes almost no effort to maintain. So I gotta ask, what in the world are you doing that it's a full time job to admin 15 gentoo boxes?
Set browser.sessionhistory.max_total_viewers to 0 and see if that helps. If it does, then you're not dealing with a memory leak (or at least, not an accidental one...they put this in there on purpose).
I'm running 1.5.0.1 on gentoo linux (no gnome or kde) and experience no memory leak. I often leave it running for days and, while my memory footprint varies with usage, it doesn't appear to be behaving baddly (memory usage always approaches a base level after I finish most of my browsing).
Could you be a little more descriptive of the memory leak problems that your experiencing?
What platform are you on? What version of Firefox are you running? What extensions to you have enabled? What types of things are you doing when you notice the memory increasing? Are you legitimately using more memory or is it actually a leak?
When they give a %-efficient, they are, indeed, talking thermodynamic efficiency, not fraction of carnot efficiency. All turbine-style power generation techniques are limited by the carnot efficiency, but modern turbines operate at such enormous pressures and temperatures that high thermodynamic efficiences are possible.
Modern power plants can and do get 60+ percent thermodynamic efficiency by using gas turbines as the primary generation step and then reclaiming the waste heat to drive a steam turbine. Google for "combined cycle" and see what you can come up with.
Replacing the gas turbines with industrial fuel cells will improve this even further.
What are you talking about? You can do the same things with LDAP and/or Kerberos. For you old-schoolers out there, NIS and a carefully structured environment will give you most of the same advantages.
If you serve all your binaries over the network (nfs, snfs, sshfs, afs, etc) and do the same with home directories and shared data directories, then managing an office of Linux machines is an absolute breeze. All you've got to do is make sure each machine boots and knows where to get authentication information (LDAP, NIS, Kerberos). Add netbooting, and you only have to worry about having a boot image for each hardware set.
Now, if you're talking about an office of Linux computers where each user has root access to his machine and is allowed to do whatever, well, then it's pretty much like running an office of Windows machines with no AD and policies in place.
The reason why Gentoo can release predictably and why Debian can't is that Gentoo allows different profiles for different architectures (Gentoo 2006.0 may have different stable versions for an app for different architectures, assuming the app is available for both arches in the first place) while Debian requires that the stable profile for each arch is synchronized.
Slashdot Mirror
Out of curiosity, what drivers are you currently missing?
Pharm companies do what you suggest and it generally gets them a one-time 3 year extension
making the effective patent duration 23 years.
RFID and wireless smartcards use something called "Inductive Coupling" to transfer information
from the card to the reader. What this means is that the antenna coils in the RFID and the
reader create a loosely coupled transformer. When the RFID or smartcard wants to send
information to the reader, it switches on/off a load connected to the antenna which changes
the impedance of the whole system, including the impedance of the antenna on the reader. These
changes in measured impedance are detected by the reader and interpretted according to
whatever protocol is used.
Now, it's very possible for several antennas to be coupled. In fact, it is specifically
allowed for by the standards (otherwise how could a reader talk to multiple RFIDs or
smartcards at the same time?). However, since there is no wave shaping (or whatever) going
on, things that would increase sensitivity in a traditional radio frequency setup (like
a pringles can or dish receiver) won't help. What matters is the distance between the
antennas and the area inside the coils multiplied by the number of coils in each respective
antenna.
The most important thing to understand is that since each antenna is coupled with each other
antenna, there is no such thing as a completely passive antenna. Each antenna added changes
the measured impedance of all other coupled antennas and, as such, can be detected when
entering or exiting the coupled system (I don't know of any hardware that attempts to detect
entering/exiting antennas).
So, is it impossible to read from a distance? No, but it is harder than with normal RF and
has much shorter range. Is it impossible to eavesdrop another communication? No, but again,
it has much shorter range and, as such, is more difficult.
As far as I know, there are no passive RFID readers, so his comment is correct. The reader
has to be powerful enough to energize the RFID tag at the distance. If it can do that, since
the RFID chip uses inductive coupling (as opposed to being a transmitter itself), then the
reader is automatically sensitive enough to read it.
If there are, they should give awards to the Gentoo and Ubuntu forums. They're absolutely
wonderful.
Now that's simply not true. Every distro has install docs that very clearly tell you how
to install the distro and explains the options available to you. Even install-intensive
distros like Gentoo can be installed without ever looking at anything other than the install
doc.
It's true that if you know nothing about Linux that the install docs might not make much
sense to you, but they'll get you to a perfectly functioning system even if you just follow
the directions without any understanding at all.
Nobody buys Mac because of the hardware no matter what they say.
Then how do you explain all the people like Linus who run Linux on Apple hardware?
They sure didn't buy it for the operating system.
Ubuntu also boasts one of the largest community bases of all the Linux distributions, called the Ubuntu Forums, which contain more than 67,000 unique registered users.
Hmm...the Gentoo forums have over 111,000 unique registered users.
As if unique forum name count was a meaningful metric of anything.
Dell Laptops have been crap for years according to every Dell laptop owner I've ever known
My work laptop is a Dell and it's a fine machine with the following exceptions:
1. Crappiest keyboard I've ever had on a laptop
2. Broadcom wireless chipset has no native Linux support. It works with ndiswrapper, but I don't trust it.
...combined with the relatively short life expectancy of a computer...
Out of curiosity, how long do you think the life expectancy of a modern computer is?
There was a time when it seemed like you needed to upgrade every 2 years or so just to have
a fast enough computer for the current software, but I think we got past that 5 or 6 years
ago. I haven't upgraded my persomal machine in 5 years (at half a gig, it's a little tight
memory-wise compared to modern machines, but the 1.2GHz AMD chip has no problem with current
software) and my laptop is about the same age. At work I have much newer machines, but I don't
really notice the speed difference except during compiles.
If you're going to give someone access to text editing but you don't trust them with
shell access, compile vi/vim/[editor of choice] without access to shell escapes. It's a
compile option for vim and, I would suspect, others. In fact, most new editors probably
don't even have a way to escape to a shell.
You can configure sudo not to allow people to 'sudo su' or 'sudo bash'.
If you bother to read the sudoers manpage, you'll see that there's a lot
you can do with sudo without necessarily giving up complete control of the
root user.
The reason we run Gentoo at work is because it takes almost no effort to
maintain. So I gotta ask, what in the world are you doing that it's a full
time job to admin 15 gentoo boxes?
If you said 50 or 100, I'd understand, but 15?
Set browser.sessionhistory.max_total_viewers to 0 and see if that helps. If it does, then
you're not dealing with a memory leak (or at least, not an accidental one...they put this
in there on purpose).
I'm running 1.5.0.1 on gentoo linux (no gnome or kde) and experience no memory leak. I often
leave it running for days and, while my memory footprint varies with usage, it doesn't appear
to be behaving baddly (memory usage always approaches a base level after I finish most of my
browsing).
Could you be a little more descriptive of the memory leak problems that your experiencing?
What platform are you on?
What version of Firefox are you running?
What extensions to you have enabled?
What types of things are you doing when you notice the memory increasing?
Are you legitimately using more memory or is it actually a leak?
C'mon, man, give us something useful.
This can be prevented by the most basic cryptographic challenge-response.
Assuming MS does it right.
Ah, yes. I didn't realize you were talking about a combined-cycle arrangement. I thought
you were talking about the fuel cell in isolation.
My apologies.
When they give a %-efficient, they are, indeed, talking thermodynamic efficiency, not fraction
of carnot efficiency. All turbine-style power generation techniques are limited by the
carnot efficiency, but modern turbines operate at such enormous pressures and temperatures
that high thermodynamic efficiences are possible.
Modern power plants can and do get 60+ percent thermodynamic efficiency by using gas turbines
as the primary generation step and then reclaiming the waste heat to drive a steam turbine.
Google for "combined cycle" and see what you can come up with.
Replacing the gas turbines with industrial fuel cells will improve this even further.
I believe that 50% of the energy released is released as heat.
That's still not bad, relative to other power generation techniques.
Do you not pay taxes on interest earned in Canada?
As far as I know, there are no federal sales taxes.
(unless you consider custom duties a sales tax)
It's not theft, it's a trade.
You gain benefit from the actions of the government, and in return, if you are able, you pay
taxes.
Just because you didn't ask the govenment to do these things for you does not release you
from this arrangement.
If you would like to suggest improvements to this arrangement, please, be bold and post them
here. We'd love to hear from you.
Could you please explain this comment in a little more detail?
What are you talking about? You can do the same things with LDAP and/or Kerberos. For
you old-schoolers out there, NIS and a carefully structured environment will give you most
of the same advantages.
If you serve all your binaries over the network (nfs, snfs, sshfs, afs, etc) and do the same
with home directories and shared data directories, then managing an office of Linux machines
is an absolute breeze. All you've got to do is make sure each machine boots and knows where to
get authentication information (LDAP, NIS, Kerberos). Add netbooting, and you only have to
worry about having a boot image for each hardware set.
Now, if you're talking about an office of Linux computers where each user has root access to
his machine and is allowed to do whatever, well, then it's pretty much like running an
office of Windows machines with no AD and policies in place.
The reason why Gentoo can release predictably and why Debian can't is that Gentoo allows
different profiles for different architectures (Gentoo 2006.0 may have different stable versions for an app for different architectures, assuming the app is available for both
arches in the first place) while Debian requires that the stable profile for each arch is
synchronized.