http://en.wikipedia.org/wiki/BP_Solar Find "solar breeder" halfway down that page.
The solar breeder factory (Fredrick, MD, USA) was a very advanced idea when it was built in the late 1970. Wikipedia mentions that the original 200 kW (peak) array has aged and is disconnected, but other arrays have been added on the site.
The 450,000 tons of steel these ships will require is only 0.3% of the world monthly steel production. http://www.worldsteel.org/?action=newsdetail&id=246 Similarly, the carbon required to produce them would be a tiny fraction of total carbon emission.
The size of the ships, and the number required, are less than that of the U.S. Liberty Ship program (1941-1945) http://en.wikipedia.org/wiki/Liberty_ship. So the required industrial effort is reasonable.
Therefore, assuming the salt-water spray concept changes albedo by the proposed magnitude and has no unacceptable consequences, this would have a very high payoff.
....but "very high payoff" and "no unacceptable consequences" are, all too often, the same as "too good to be true".
Most newer (since about 1970s) US home developments are set up with homeowner associations. They manage common areas (playgrounds, pools, etc.) and establish rules (including fines) to ensure all properties maintain a good appearance. Covenants which must be conveyed with the title ensure each homeowner is obligated to play along. In almost all communities, the rules prohibit visible antennas on the justification they are an eyesore.
Homeowner association rules were putting satellite TV providers at such a disadvantage (compared to cable providers) that congress passed a law (about 1990) forcing homeowner associations to permit the newer, smaller antennas (less than a meter across). Older satellite antennas (three meter diameter) and broadcast antennas are still fair game.
Us stubborn people who don't want to pay for cable or satellite get by with rabbit ears or (like me) are willing to self-install an attic antenna.
Per http://en.wikipedia.org/wiki/Kerberos_(protocol), Kerberos is a symmetric key system which requires a trusted Key Distribution Center to also know the shared secret (a one-way hash of your password). The advantage is that a phisher (who doesn't have your secret) can't pry it out of you if . It does have the weaknesses common to symmetric encryption systems; KDC compromise, KDC unavailability, etc.
Public Key Infrastructure encrypts the transmissions with the public key of the destination entity instead of a shared symmetric key. Kerberos has extensions to work with PKI. In these, the KDC doesn't know your secret, but can recognize that you know it.
Operating Systems will have a secure storage intended to keep your private key from being slurped by a trojan. PKI hardware tokens improve on that by moving the private key into a separate device, with its own single-purpose operating system (which is easier to certify, as long as you stick with well-vetted algorithms instead of http://yro.slashdot.org/article.pl?sid=08/08/09/1812256). The private key never leaves the token; all operations requiring it are done inside the token. To crack this requires two separate cracks; physically obtaining the token, plus phishing, sniffing, or torturing the corresponding PIN from the token owner.
So you can pick how much security you want, and how much you want to pay for it. It helps to make both decisions at the same time.
I appologize to all/.ers but I did RTFA. (Insert appropriate smiley here.)
The title (which came directly from the New Scientist article) comes from a single, deeply buried paragraph.
"The lenses could also help refine a technique to transfer power wirelessly developed in 2006. The new lenses could create more energy-dense beams of the electromagnetic waves used to transfer power, Grbic says."
The gadget-powering technique works in the near-field, like the lens does, but would need a low frequency (~3 MHz) so the near field can include a whole room. I suspect Grbic spoke without thinking through the frequency issue; microwave techniques rarely scale to hundred-meter wavelengths.
The real news was the development of a material design which could be more easily mass produced. So the New Scientist choice of title suggests the meme "It's not news, it's...."
Also, equation 14 of Near-Field Focusing Plates and Their Design (Grbic and Merlin) means the field strength at the focal point ~ e^-BIGNUM for any application involving orbital distances. This makes a lot of interesting comments OT. If the mods understand the implications and delete all the appropriate OT posts, I expect my karma to drop to ~ e^-USERNUM.
I think you are correct that the technique is related to phase-shift masking. Yes, the article is incomplete for failing to mention that some progress has been made past the 'classical' diffraction limit.
You mention the many design constraints which must be satisfied to be successful. Some of these limitations are probably due to the limited range of properties achievable in available masking materials.
The more generalized technique requires use of 'meta-materials' with properties which can be exotic (e.g., negative refractive index) and can be varied to suit.
The planar material can be more easily manufactured, making it one more step toward actual application. In other words...
Invent meta-materials ??? <-- Insert new development Profit!
I, too, think you are underestimating the hardware problem. In addition to the thoughtful comments already posted:
The Microtransat Challenge 2007 rules require length not to exceed four meters and total mass not over fourty kilograms. (The 2008 transatlantic race rules don't seem to be posted yet.) These appear to be "soft" rules (imposing penalty points, not disqualification).
Sailing Kayak "Pentafulle" http://www.nonnalilla.org/ is a random example of a four meter boat. At 25 kilograms, she only allows 15 kilograms for everything else. She is obviously not ready for open ocean, and all the necessary changes add mass. My first change would be to add at least 15 kilograms of ballast to the keel.... (How fast do the penalty points accumulate?)
Power provisioning: It's harder than you think. A quick calculation suggests that the available deck area won't collect enough solar power to feed more than a very frugal CPU plus actuators. (And too bad if the available wind makes you heel to the north.) The drag of a propeller generator may be significant on this small rig with a hull speed of only ~4 knots (~2 m/s).
Heavy weather: The sail reefing/furling systems which lend themselves to automation are the ones which jam at inconvenient times. It may be more practical to design the boat to treat a knockdown as part of its normal operating envelope.
Collision avoidance: Although the number of obstacles is less than in ARPA's desert driving grand challenge, the problem isn't easier. My power calculations seem to rule out radar. Vision systems will have to cope with limited height and moving clutter which doesn't have a height limit.
Liability: For the desert driving Grand Challenge, ARPA solved the insurance problem by temporarily taking ownership of the vehicles for the duration of the actual run. No such protection here. Lawyer up, and keep the chase boat close at hand.
FTA: "The team fed the algorithm as much data as they could from the Cisco patent and told the software to design around it. It succeeded in doing so. The result is a design that does not infringe Cisco's patent--and is more efficient to boot."
The new design appears totally dependent upon Cisco's patent claims, even if in a negative sense. Could a lawyer might make a case for infringement out of this? IANAL, so I don't know how strong the case would be.
Slashdot Mirror
http://en.wikipedia.org/wiki/BP_Solar Find "solar breeder" halfway down that page. The solar breeder factory (Fredrick, MD, USA) was a very advanced idea when it was built in the late 1970. Wikipedia mentions that the original 200 kW (peak) array has aged and is disconnected, but other arrays have been added on the site.
The 450,000 tons of steel these ships will require is only 0.3% of the world monthly steel production. http://www.worldsteel.org/?action=newsdetail&id=246 Similarly, the carbon required to produce them would be a tiny fraction of total carbon emission.
The size of the ships, and the number required, are less than that of the U.S. Liberty Ship program (1941-1945) http://en.wikipedia.org/wiki/Liberty_ship. So the required industrial effort is reasonable.
Therefore, assuming the salt-water spray concept changes albedo by the proposed magnitude and has no unacceptable consequences, this would have a very high payoff.
....but "very high payoff" and "no unacceptable consequences" are, all too often, the same as "too good to be true".
Most newer (since about 1970s) US home developments are set up with homeowner associations. They manage common areas (playgrounds, pools, etc.) and establish rules (including fines) to ensure all properties maintain a good appearance. Covenants which must be conveyed with the title ensure each homeowner is obligated to play along. In almost all communities, the rules prohibit visible antennas on the justification they are an eyesore.
Homeowner association rules were putting satellite TV providers at such a disadvantage (compared to cable providers) that congress passed a law (about 1990) forcing homeowner associations to permit the newer, smaller antennas (less than a meter across). Older satellite antennas (three meter diameter) and broadcast antennas are still fair game.
Us stubborn people who don't want to pay for cable or satellite get by with rabbit ears or (like me) are willing to self-install an attic antenna.
Per http://en.wikipedia.org/wiki/Kerberos_(protocol), Kerberos is a symmetric key system which requires a trusted Key Distribution Center to also know the shared secret (a one-way hash of your password). The advantage is that a phisher (who doesn't have your secret) can't pry it out of you if . It does have the weaknesses common to symmetric encryption systems; KDC compromise, KDC unavailability, etc.
Public Key Infrastructure encrypts the transmissions with the public key of the destination entity instead of a shared symmetric key. Kerberos has extensions to work with PKI. In these, the KDC doesn't know your secret, but can recognize that you know it.
Operating Systems will have a secure storage intended to keep your private key from being slurped by a trojan. PKI hardware tokens improve on that by moving the private key into a separate device, with its own single-purpose operating system (which is easier to certify, as long as you stick with well-vetted algorithms instead of http://yro.slashdot.org/article.pl?sid=08/08/09/1812256). The private key never leaves the token; all operations requiring it are done inside the token. To crack this requires two separate cracks; physically obtaining the token, plus phishing, sniffing, or torturing the corresponding PIN from the token owner.
So you can pick how much security you want, and how much you want to pay for it. It helps to make both decisions at the same time.
I appologize to all /.ers but I did RTFA. (Insert appropriate smiley here.)
The title (which came directly from the New Scientist article) comes from a single, deeply buried paragraph.
"The lenses could also help refine a technique to transfer power wirelessly developed in 2006. The new lenses could create more energy-dense beams of the electromagnetic waves used to transfer power, Grbic says."The gadget-powering technique works in the near-field, like the lens does, but would need a low frequency (~3 MHz) so the near field can include a whole room. I suspect Grbic spoke without thinking through the frequency issue; microwave techniques rarely scale to hundred-meter wavelengths.
The real news was the development of a material design which could be more easily mass produced. So the New Scientist choice of title suggests the meme "It's not news, it's...."
Also, equation 14 of Near-Field Focusing Plates and Their Design (Grbic and Merlin) means the field strength at the focal point ~ e^-BIGNUM for any application involving orbital distances. This makes a lot of interesting comments OT. If the mods understand the implications and delete all the appropriate OT posts, I expect my karma to drop to ~ e^-USERNUM .
I think you are correct that the technique is related to phase-shift masking. Yes, the article is incomplete for failing to mention that some progress has been made past the 'classical' diffraction limit.
You mention the many design constraints which must be satisfied to be successful. Some of these limitations are probably due to the limited range of properties achievable in available masking materials.
The more generalized technique requires use of 'meta-materials' with properties which can be exotic (e.g., negative refractive index) and can be varied to suit.
The planar material can be more easily manufactured, making it one more step toward actual application. In other words...
Invent meta-materials
??? <-- Insert new development
Profit!
I, too, think you are underestimating the hardware problem. In addition to the thoughtful comments already posted:
The Microtransat Challenge 2007 rules require length not to exceed four meters and total mass not over fourty kilograms. (The 2008 transatlantic race rules don't seem to be posted yet.) These appear to be "soft" rules (imposing penalty points, not disqualification).
Sailing Kayak "Pentafulle" http://www.nonnalilla.org/ is a random example of a four meter boat. At 25 kilograms, she only allows 15 kilograms for everything else. She is obviously not ready for open ocean, and all the necessary changes add mass. My first change would be to add at least 15 kilograms of ballast to the keel.... (How fast do the penalty points accumulate?)
Power provisioning: It's harder than you think. A quick calculation suggests that the available deck area won't collect enough solar power to feed more than a very frugal CPU plus actuators. (And too bad if the available wind makes you heel to the north.) The drag of a propeller generator may be significant on this small rig with a hull speed of only ~4 knots (~2 m/s).
Heavy weather: The sail reefing/furling systems which lend themselves to automation are the ones which jam at inconvenient times. It may be more practical to design the boat to treat a knockdown as part of its normal operating envelope.
Collision avoidance: Although the number of obstacles is less than in ARPA's desert driving grand challenge, the problem isn't easier. My power calculations seem to rule out radar. Vision systems will have to cope with limited height and moving clutter which doesn't have a height limit.
Liability: For the desert driving Grand Challenge, ARPA solved the insurance problem by temporarily taking ownership of the vehicles for the duration of the actual run. No such protection here. Lawyer up, and keep the chase boat close at hand.
FTA: "The team fed the algorithm as much data as they could from the Cisco patent and told the software to design around it. It succeeded in doing so. The result is a design that does not infringe Cisco's patent--and is more efficient to boot."
The new design appears totally dependent upon Cisco's patent claims, even if in a negative sense. Could a lawyer might make a case for infringement out of this? IANAL, so I don't know how strong the case would be.