This boat will achieve its 7,000-mile trip [...] without burning a single gallon of fuel.
Unless you consider the fuel required to manufacture the solar cells, including the vast amount of electricity consumed during manufacturing and refining of materials which mostly comes from burning coal and the transportation of raw materials and intermediate products over long distances using oil fuel.
Not too long ago it was more than the usable energy the cell could produce over its entire lifetime. It's no longer that bad but it's still far from where we'd like it to be.
Quite easy to get in: if your mailserver is sending out lots of spam, yes it is, and it should be. It is the sign of a mailserver that is misconfigured, insecure, or just has bad policies.
My server is sending out lots of spam but it is not misconfigured or insecure and I don't believe my policies are bad.
I have set up forwarding addresses for some people and some of them are receiving lots of spam. This means that my server is sending out lots of spam and I think it has already been blacklisted by at least one other provider.
The best place to put spam filtering is at the endpoint - that's where the most information is available to make the decision and the end user can intervene and provider feedback to the classifier (e.g. gmail). If I start filtering spam, in the hope of reducing the chances of being blacklisted, I will be doing a disservice for my users.
Convert the temperature readings with voltage-to-frequency converters. This digital signal is very robust and can be carried over long distances on unshielded wires with no loss of accuracy. The frequency counters and computers can then be mounted outside the warehouse. You can put a DC power supply and an AC signal on the same wire pair with AC coupling for the signal.
I'm pretty sure it's easier to find a V2F converter to run at these temperatures than PCs and networking equipment.
GPS coordinates are relative to the center of gravity of the Earth (i.e. average position of all the mass on Earth) and the rotation axis of the Earth. Longitude is tracked by measuring the average rate of rotation from pulsar signals received in several radiotelescopes around the earth.
It's all based on averages. The motion of the crust in the biggest earthquakes is still insignificant compared to the total mass of the entire volume of the Earth so it doesn't really affect the GPS frame of reference. The effect on the rate of rotation is small but integrated over time it can accumulate to a significant difference. It is cancelled by the tracking of the rate of rotation.
In the affected area you will notice the difference in the coordinates of landmarks because they really did move relative to the average position of the Earth. If this ever becomes an issue it should be possible to generate a list of polygons and their motion vectors and transmit it as part of the GPS signal. The receiver could then let the user choose between true coordinates and coordinates corrected to some reference point in time before the earthquake.
zfs is administered via the zpool(1m) and zfs(1m) command line utilities. They're quite a bit more friendly than most tools for managing raid, volumes and filesystems I've encoutered so far.
ZFS blurs the traditional boundaries between volume management, RAID and file systems. All disks are added into one big pool that can be carved out into either the native ZFS filesystem format or virtual volumes that can be formatted as other filesystem formats. It has many other interesting features like instantaneous snapshots and copy-on-write clones.
So that more people sell stuff on ebay (greed, you see). eBay would love to get more people listing stuff because they take about 10% of the purchase price.
If you don't want eBay's services you are welcome to hold an auction directly on your personal web site.
Why this focus on a few people getting rich? In general, the economic benefit of the internet is spread across many people. Customers that have a slightly cheaper alternative one click away. Suppliers that gain access to markets that they could not access effectively otherwise. The overall effect on the economy is enourmous but only a few people are getting really rich.
How many are making a decent living off eBay sales? How many people's lives have been transformed by the ability to give up their day job and do what they like while getting paid for it?
For example this artist who left her job as a web designer nad is now making lampwork glass beads and selling them on eBat.
Disclaimer: I know her personally and this is a bit of promotion - but I think it's a valid example because it would be difficult for someone living in a remote place to have this kind of access to the markets that appreciate her art without eBay.
Erm, you still have to get the fuel up there right?.. and the cost of putting something up there is still reasonably proportional to weight?
The nice thing about fuel is that unlike people or equipment you don't really care how it gets there: lots of small launches or a few bigger launches, high Gs or a gentle ride, expendable or reusable, winged or VTVL, high or low reliability. Whatever.
Some people claim launch costs can be reduced by somewhere between one and two orders of magnitude using only existing technology, a bit of clever engineering and streamlined operations. I don't know if that's true but a good way to find out is for NASA to announce that it will be buying fuel in orbit and let entrepreneurs fight it out on who can do it at the lowest cost.
One of the problems with the current way NASA is doing "business" in space is that it dictates the technology and architecture. This way we'll never know if alternative approaches can work better.
The power to weight ratio of electric motors is much better than gasoline. The stored energy to weight ratio of batteries is still much worse than a tank of gasoline. So if you want to build a car with excellent acceleration but don't care much how far it can go on a single tank/charge then electric is definitely the way to go.
This power to weight ratio also makes electric motors attractive for helicopters - they simply can't get off the ground unless they exceed a thrust to weight ratio of 1:1. The length of the flight is very limited, though, so it's only used in toy helicopters.
Take a look at this cute 6.9 gram electric helicopter!
Rockets are similar: they have a fantastic power to weight ratio compared to jet engines but need more total propellant because they also have to carry the oxidizer. If you want maximum acceleration and don't care too much about range use a rocket, even if you are inside the atomosphere and don't really need to carry the oxidizer.
You can count on manufacturers to come up with ways to make batteries that are removable as required by new EU laws but not replacable (or at least very expensive to replace) so your mp3/whatever is still guaranteed to be unusable in two years.
Encrypted key exchange protocols (e.g. EKE, SPEKE) allow the safe use of relatively weak passwords. They resist all known passive sniffing, man-in-the-middle and offline dictionary attacks. How can a system be secure with weak passwords? Think of your ATM card's 4-digit PIN: it's pretty safe because it's limited to only a couple of unsuccessful attempts and you can't do an offline dictionary attack that would bypass this limit.
Unfortunately, these algorithms are all patented.
As far as I can tell, the SRP system infringes on the EKE patent. The fact that Stanford got a patent for SRP means nothing - a patent grant says nothing about infringement of other patents. AT&T probably won't sue anyone using it in an open source project but they will not issue a statement that SRP does not infringe the Bellovin patent, either. Result: commercial users shy away from SRP.
The only widely deployed remote password authentication mechanism which is safe even with weak passwords is "plaintext over SSL" but it relies on PKI which has its own set of problems.
Kerberos tickets are pretty secure because they use machine-generated random keys instead of user-provided passwords. But this whole tower is built on a weak foundation because the initial authentication to the TGT does use the weak user password. If just this part was replaced by EKE all Kerberos services would benefit from increased security.
Microsoft domains use Kerberos. Is there any chance Microsoft would bite the bullet and pay the EKE or SPEKE patent license fees?
He is not talking about COW in general. Linux *does* use COW for fork.
He is referring to a specific "optimization" of zero-copy I/O where instead of copying the user buffers to temporary kernel buffers the I/O is performed directly from the user buffers and the pages are COWed to make sure the program doesn't change them after the write call but before the data has actually been transmitted to the network, written to disk, etc.
Using COW in this case may sound clever but the fact is that linear memory copy is extremely fast and updating the page table and flushing the TLB cache across multiple CPUs is very slow.
It seems that the FreeBSD developers were "too clever" in this case. I am still somewhat surprised at the words he used to express his opinion of them. Linus is usually pretty diplomatic.
Any particulate is potentially harmful to lungs
on
Nanotech Gone Awry?
·
· Score: 4, Insightful
Any particulate is potentially harmful to lungs. Even the most benign materials. Our lungs are designed to breathe gas, not solids.
Surround is sometimes used for effects of things happening behind you but that is not its primary purpose. Surround is for ambient effects. What's why dipole speakers are often used. The direct sound component is cancelled by the two out-of-phase sources and you get mostly the non-directional reflections.
Ambient effects are important for the overall impact of the movie. Really good sound is not something you notice consciously - it sets the atmosphere and emotional tone without being conspicuous.
There is a surplus of nuclear fuel from decomissioned nuclear warheads and the cost of fuel is a pretty small part of the cost of nuclear energy anyway. So why recycle?
High-burnup fast reactors are interesting, but the current technology being promoted (IFR) is cooled by molten sodium. I don't know about you, but I don't like the concept of handling so many tons of liquid that ignites in contact with air and explodes on contact with water.
Yes. People will die in these rocket races. People die on car race tracks. People die surfing. People die exploring Antrarctica, too.
NASA astronauts are treated like national treasures which must be protected at any cost. The whole country goes into mourning when they die and the space program is halted for years. When people will die in these races their comrades will drink to their memory in the evening and climb into another rocket vehicle the next morning.
These rocket races will give small companies a chance to get their hands dirty with rocket engines. The engines that will eventually power the vehicles that take us to space.
Slashdot Mirror
> The first place is your home, the second place is work.
In which one of them do you spend more of your waking hours?
This boat will achieve its 7,000-mile trip [...] without burning a single gallon of fuel.
Unless you consider the fuel required to manufacture the solar cells, including the vast amount of electricity consumed during manufacturing and refining of materials which mostly comes from burning coal and the transportation of raw materials and intermediate products over long distances using oil fuel.
Not too long ago it was more than the usable energy the cell could produce over its entire lifetime. It's no longer that bad but it's still far from where we'd like it to be.
Quite easy to get in: if your mailserver is sending out lots of spam, yes it is, and it should be. It is the sign of a mailserver that is misconfigured, insecure, or just has bad policies.
My server is sending out lots of spam but it is not misconfigured or insecure and I don't believe my policies are bad.
I have set up forwarding addresses for some people and some of them are receiving lots of spam. This means that my server is sending out lots of spam and I think it has already been blacklisted by at least one other provider.
The best place to put spam filtering is at the endpoint - that's where the most information is available to make the decision and the end user can intervene and provider feedback to the classifier (e.g. gmail). If I start filtering spam, in the hope of reducing the chances of being blacklisted, I will be doing a disservice for my users.
Convert the temperature readings with voltage-to-frequency converters. This digital signal is very robust and can be carried over long distances on unshielded wires with no loss of accuracy. The frequency counters and computers can then be mounted outside the warehouse. You can put a DC power supply and an AC signal on the same wire pair with AC coupling for the signal.
I'm pretty sure it's easier to find a V2F converter to run at these temperatures than PCs and networking equipment.
GPS coordinates are relative to the center of gravity of the Earth (i.e. average position of all the mass on Earth) and the rotation axis of the Earth. Longitude is tracked by measuring the average rate of rotation from pulsar signals received in several radiotelescopes around the earth.
It's all based on averages. The motion of the crust in the biggest earthquakes is still insignificant compared to the total mass of the entire volume of the Earth so it doesn't really affect the GPS frame of reference. The effect on the rate of rotation is small but integrated over time it can accumulate to a significant difference. It is cancelled by the tracking of the rate of rotation.
In the affected area you will notice the difference in the coordinates of landmarks because they really did move relative to the average position of the Earth. If this ever becomes an issue it should be possible to generate a list of polygons and their motion vectors and transmit it as part of the GPS signal. The receiver could then let the user choose between true coordinates and coordinates corrected to some reference point in time before the earthquake.
zfs is administered via the zpool(1m) and zfs(1m) command line utilities. They're quite a bit more friendly than most tools for managing raid, volumes and filesystems I've encoutered so far.
This fits nicely with Sun's new ZFS file system.
ZFS blurs the traditional boundaries between volume management, RAID and file systems. All disks are added into one big pool that can be carved out into either the native ZFS filesystem format or virtual volumes that can be formatted as other filesystem formats. It has many other interesting features like instantaneous snapshots and copy-on-write clones.
So that more people sell stuff on ebay (greed, you see). eBay would love to get more people listing stuff because they take about 10% of the purchase price.
If you don't want eBay's services you are welcome to hold an auction directly on your personal web site.
Why this focus on a few people getting rich? In general, the economic benefit of the internet is spread across many people. Customers that have a slightly cheaper alternative one click away. Suppliers that gain access to markets that they could not access effectively otherwise. The overall effect on the economy is enourmous but only a few people are getting really rich.
How many are making a decent living off eBay sales? How many people's lives have been transformed by the ability to give up their day job and do what they like while getting paid for it?
For example this artist who left her job as a web designer nad is now making lampwork glass beads and selling them on eBat.
Disclaimer: I know her personally and this is a bit of promotion - but I think it's a valid example because it would be difficult for someone living in a remote place to have this kind of access to the markets that appreciate her art without eBay.
Hmm... I'd kind of like to buy a RAID card that is accelerated for database and/or search work.
RAID card? irrelevant. Google's entire production database is in RAM. Disks are just for boot and persistence.
For more information about the challenges in achieving a true driversless car check this Wikipedia Article
Does this spell the end for the true relational storage paradigm that Microsoft has been promising since Windows 95?"
Well, who wants a RELATIONAL filesystem anyway? I'd rather much have a filesystem with search-engine like capabilities. Tags, keywords, etc.
An SSL connection to your jabber server is enough. No need for end-to-end encryption. If you don't trust your own internal server, what DO you trust?
Erm, you still have to get the fuel up there right? .. and the cost of putting something up there is still reasonably proportional to weight?
The nice thing about fuel is that unlike people or equipment you don't really care how it gets there: lots of small launches or a few bigger launches, high Gs or a gentle ride, expendable or reusable, winged or VTVL, high or low reliability. Whatever.
Some people claim launch costs can be reduced by somewhere between one and two orders of magnitude using only existing technology, a bit of clever engineering and streamlined operations. I don't know if that's true but a good way to find out is for NASA to announce that it will be buying fuel in orbit and let entrepreneurs fight it out on who can do it at the lowest cost.
One of the problems with the current way NASA is doing "business" in space is that it dictates the technology and architecture. This way we'll never know if alternative approaches can work better.
The power to weight ratio of electric motors is much better than gasoline. The stored energy to weight ratio of batteries is still much worse than a tank of gasoline. So if you want to build a car with excellent acceleration but don't care much how far it can go on a single tank/charge then electric is definitely the way to go.
This power to weight ratio also makes electric motors attractive for helicopters - they simply can't get off the ground unless they exceed a thrust to weight ratio of 1:1. The length of the flight is very limited, though, so it's only used in toy helicopters.
Take a look at this cute 6.9 gram electric helicopter!
Rockets are similar: they have a fantastic power to weight ratio compared to jet engines but need more total propellant because they also have to carry the oxidizer. If you want maximum acceleration and don't care too much about range use a rocket, even if you are inside the atomosphere and don't really need to carry the oxidizer.
You can count on manufacturers to come up with ways to make batteries that are removable as required by new EU laws but not replacable (or at least very expensive to replace) so your mp3/whatever is still guaranteed to be unusable in two years.
Encrypted key exchange protocols (e.g. EKE, SPEKE) allow the safe use of relatively weak passwords. They resist all known passive sniffing, man-in-the-middle and offline dictionary attacks. How can a system be secure with weak passwords? Think of your ATM card's 4-digit PIN: it's pretty safe because it's limited to only a couple of unsuccessful attempts and you can't do an offline dictionary attack that would bypass this limit.
Unfortunately, these algorithms are all patented.
As far as I can tell, the SRP system infringes on the EKE patent. The fact that Stanford got a patent for SRP means nothing - a patent grant says nothing about infringement of other patents. AT&T probably won't sue anyone using it in an open source project but they will not issue a statement that SRP does not infringe the Bellovin patent, either. Result: commercial users shy away from SRP.
The only widely deployed remote password authentication mechanism which is safe even with weak passwords is "plaintext over SSL" but it relies on PKI which has its own set of problems.
Kerberos tickets are pretty secure because they use machine-generated random keys instead of user-provided passwords. But this whole tower is built on a weak foundation because the initial authentication to the TGT does use the weak user password. If just this part was replaced by EKE all Kerberos services would benefit from increased security.
Microsoft domains use Kerberos. Is there any chance Microsoft would bite the bullet and pay the EKE or SPEKE patent license fees?
He is not talking about COW in general. Linux *does* use COW for fork.
He is referring to a specific "optimization" of zero-copy I/O where instead of copying the user buffers to temporary kernel buffers the I/O is performed directly from the user buffers and the pages are COWed to make sure the program doesn't change them after the write call but before the data has actually been transmitted to the network, written to disk, etc.
Using COW in this case may sound clever but the fact is that linear memory copy is extremely fast and updating the page table and flushing the TLB cache across multiple CPUs is very slow.
It seems that the FreeBSD developers were "too clever" in this case. I am still somewhat surprised at the words he used to express his opinion of them. Linus is usually pretty diplomatic.
Any particulate is potentially harmful to lungs. Even the most benign materials. Our lungs are designed to breathe gas, not solids.
Nano is just the latest example of that.
A few months ago Hossein Derakhshan made a visit to Israel. This means he probably won't be going back to Iran in the near future.
Surround is sometimes used for effects of things happening behind you but that is not its primary purpose. Surround is for ambient effects. What's why dipole speakers are often used. The direct sound component is cancelled by the two out-of-phase sources and you get mostly the non-directional reflections.
Ambient effects are important for the overall impact of the movie. Really good sound is not something you notice consciously - it sets the atmosphere and emotional tone without being conspicuous.
There is a surplus of nuclear fuel from decomissioned nuclear warheads and the cost of fuel is a pretty small part of the cost of nuclear energy anyway. So why recycle?
High-burnup fast reactors are interesting, but the current technology being promoted (IFR) is cooled by molten sodium. I don't know about you, but I don't like the concept of handling so many tons of liquid that ignites in contact with air and explodes on contact with water.
Phishing Site Using Valid SSL Certificates.
Most 9/11 attackers had valid IDs.
News at 11.
Yes. People will die in these rocket races. People die on car race tracks. People die surfing. People die exploring Antrarctica, too.
NASA astronauts are treated like national treasures which must be protected at any cost. The whole country goes into mourning when they die and the space program is halted for years. When people will die in these races their comrades will drink to their memory in the evening and climb into another rocket vehicle the next morning.
These rocket races will give small companies a chance to get their hands dirty with rocket engines. The engines that will eventually power the vehicles that take us to space.