Nitrogen can't exist as a gas at a given temperature and arbitrarily high pressure. Read about phase transitions. Liquid nitrogen is about 0.8 the density of water. If you try to squeeze it to make it neutrally buoyant, it will liquefy before it gets to the density of water.
Um, how do you intend to keep bags of air at any depth underwater? Even when highly compressed, the density ratio is going to cause buoyancy, requiring some anchoring mechanism and a bag that is structurally sound enough to handle the stresses. I don't think that you can compress air enough to get it to match the density of liquid water at any depth...the nitrogen will start to liquefy first...and that brings a whole different set of problems.
Um, 50 gigawatt hours is about 1.8 * 10^14 joules. That is about 43 kilotons of energy. Now think catastrophic failure. Here is an example 1/10 the size.
All energy storage systems...especially physical storage systems...suffer from the same problem. In order to store a useful amount of energy, they need to exist on a potentially catastrophic scale. Pump storage...where is the flood plane. Compressed air...what is the blast radius, where will the supercooled plume go, will it reach aviation altitudes? Flywheel storage...reference mythbusters with the CD on a die grinder. And while not a storage system, even geothermal power plants seem to cause geological instability.
A few years ago, I did some modelling development for people doing salt mining for compressed air storage. (IAAMechEngineer.) At the time, I remember thinking what must the hoop stresses on a 100m cavern look like at a few hundred atmospheres? And that is rock and dirt and salt holding it together. Nothing in that system tends to behave elastically. So pressurizing and depressurizing it has to induce crack growth and eventually some geological instability. How do you do in-situ inspection of your "pressure vessel"?
In my mind, some electrochemical process is far safer, even if it uses nasty chemical. Because you can keep the chemical apart (with 100-ft high berms if need be) until it is time to react them.
I can't wait for this newest bubble to burst. Thin clients haven't really been embraced for office apps where 95% of the functionality can run in the browser and it will work reasonably well. How can you expect to compete with native apps on PCs where performance is cheaply had so long as you don't need to run at the highest settings...or on consoles which look almost as good? The problem for game companies is that many folks have realized that they can play year old games on cheap new hardware to great effect...after the game is reduced to 50%.
I don't see the market niche. Hardcore gamers won't touch it. Casual gamers will baulk at the $15/month by in BEFORE you get the privilege to buy/rent a game. So, who will want this unless the games are steeply discounted? $180/year could be well spent on local hardware upgrades.
This was posted above. It accomplishes the same goal as port knocking, but removes all of the timing issues and replay attack vectors. All of the communication is cryptographically signed and encrypted and done via a closed port.
I agree completely. We use fwknop as a part of a required two-factor authorization scheme for a US Government customer. It is a minor inconvenience to use it to open the ssh port before connecting, but it virtually eliminates attack attempts. How can you hack a closed port?
What you are describing already has been explored in various forms. These cells are essentially batteries, but when the are run down, they are "recharged" by flushing them with fuel to reduce the oxides back to a reactive state. I forget what they are called, but they have been tried. There are LOTS of ways to make fuel cells. Any 1st semester chem book tells you how to find the electrical potential of a given reaction. The problem is trying to make something robust, efficient, and stable.
Expensive to install. Reliability is a huge concern because they are ceramic and hence naturally brittle. But they also have rather large temperature gradients in them (part of what I was studying). Those gradients produces thermal stress which could really shorten the life of these things...you are talking about electrodes and electrolytes with thickness measured in 10s of microns, being heated by activation and ohmic losses on the inside, and cooled by reactant flows on the outside. Reliability, especially under transient loads, used to be a real concern. I'm sure that they have worked around many of the problems, either with careful control logic or special materials or both.
Also, sealing these things was a real PITA too. Leaks from one reactant stream into the other turned the fuel cell into a combustor. There were other problems...someone above mentioned sulfer poisoning, so the syngas or whatever needs to be scrubbed. Also, ion migration was a problem. Due to the high temperature, the various ions in the electrodes and catalysts could redistribute themselves, not unlike what can happen in ICs that are run too hot or at too high a voltage.
It is a new technology. DOE dumped a ton of money into research under the SECA program about 8-10 years ago. Their target was development of these little component units that could be deployed a few at a time or ganged together into a massively parallel power plant configuration. I'm glad to see someone at least got something out to market.
These are solid oxide fuel cells (SOFCs). The catalyst is probably a little bit of nickel or some other fairly abundant metal. Platinum and/or palladium are needed as catalysts only for low temperature polymer electrolyte membrane (PEM) fuel cells.
Also, PEM fuel cells can be poisoned by carbon in the fuel stream. SOFCs can pretty easily oxidize CO and H2 and possibly even CH4 or C2H6 due to water-gas shift reactions.
IAA Mech Eng. I spent six years writing software to model both kinds of fuel cells.
The Google presentation noted above discusses the triple product and shows to be much closer to break-even than IEC and think a bit better than the Tokamak.
Your point about carbon neutrality is valid, but there is a reason for the pursuit of a safe, inexpensive hydrogen storage system. The PEM fuel cells that car manufacturers have been developing do not respond well to exposure to any hydrocarbon (except methanol). The short story is that carbon compounds foul the catalysts and ruin the fuel cell performance. For these systems, it would be ideal to feed them pure hydrogen from a storage tank. The other alternative is reform some hydrocarbon into hydrogen gas on the fly. That requires more energy and more equipment (more weight both for the reformer and for the carbon in the fuel that can't be used) and ultimate impacts the operational efficiency of the car. Pure hydrogen fuel makes the fuel cell system much lighter, cheaper, and easier to design and manufacture. The production of the pure H2 can be moved off to stationary reformer/production facilities.
So this is great news. I have long been skeptical about the feasibility of fuel cell cars with hydrogen storage being one of my main concerns. This new approach has the potential to remove it from my list. Of course, you still have the hydrogen production problem (what is the end-to-end efficiency?), the freezing problem (PEMs have hydrated membranes and water freezes), and the catalyst problem (how much platinum and palladium is there in the world?)
OK, if you actually programmed vector processors, you'd know that the current CPU development is largely heading in the direction of vector processing--not with multicores, but with SSE4/altivec/MMX and especially with GPUGP. The approaches for making most common numerical algorithms work well on vector CPUs were sorted out on the original Cray machines in the 80s.
One question that both AMD and Intel are asking is the target application for more CPU. Intel has their pet ray-tracing app, etc. For encoding/decoding video, numerical simulations, etc., there is excellent evidence that wide SIMD vector-type operations can give dramatic performance increases...see the aforementioned GPUGP. What Intel/AMD may decide is that more real world performance can be found by limiting core count and provide 8-wide or 16-wide SIMD instructions and allow the 20-year-old vectorizing compiler techniques to exploit that parallelism. Four cores with 16-wide SIMD instructions is probably far better than 16 cores with 4-wide SIMDs.
The analogous situation currently exists with small propane tanks for gas grills, etc. There are dozens of places that have racks of these ready to swap with your old one. I think this is an excellent business model. Each location will need to an inventory of batteries that is equal to the peak turn-over rate times the recharge time plus a bit of a cushion. The trick is getting automakers first to build electric cars at all and second to agree on a standard battery module.
He claims that this is equivalent to the Carnot cycle...specifically it is an Ericsson cycle. It still has the same (low) fundamental efficiency for small temperature differences. This is unlike a fuel cell which is not a heat engine and the Carnot limit doesn't apply. His target application is solar concentrators so the temperature difference would be much higher.
The problems with SOFCs are numerous. First, they are ceramic so they are brittle. So, they need to run at a more-or-less constant and uniform operating temperature. Thermal gradients in the system lead to differential expansion and thermal stress. Placing a ceramic in tension is a good way to find out that you need to buy a new ceramic.
Second problem is sealing. You need to build stacks of cells in order to get a decent operating voltage out of the system. This requires a sandwiching scheme of some type...there are different approaches, all with their own drawbacks. But sandwiching always leads to the possibility of leaks between cells...fuel in the air stream or vice versa and you no longer have a fuel cell--you have a combustor. These things operate at 800-1000 C, the normal sealing technologies are not useful.
Another problem is ionic migration. Things you uses in seals or supports or electrical or thermal management can all allow ions to migrate into the electrochemically active part of the cell and that can poison the system. Or the catalyst that is necessary to allow the electrochemical reactions can migrate away from the three-phase boundaries and reduce efficiency.
Another problem is ohmic losses. The current carrying parts of the cell are doped ceramics. These are not the most electrically conductive materials, so ohmic losses (and the resultant heating) can be a problem.
Just building the things is a problem. You have two different ceramic compounds with two different coefficients of thermal expansion. They have to be sintered together somehow. The layers need to be very thin to cut down ohmic and diffusion losses. And electrolyte needs to not leak. Making all of this work is something of a black art. Most test cells are only a few square inches. Scaling production up so that you can get a planar cell that something like a 1 ft on a side is still a daunting task. I think the folks doing tubular cells (including Accumetrics) may have an easier time of this, but again, they have there own manufacturing issues.
If you run the cell on anything but pure H2, you run the risk of coking the thing up. These are porous ceramic parts with lots of tiny passages through which reactants must diffuse. If you get the conditions wrong, atomic carbon can precipitate and plug the thing up.
I could go on and on.
Honestly, there hasn't been much interest in SOFCs until maybe six or seven years ago. Only a handful of companies have pursued the technology. There are still advances to be made in material science and material processing, but I think even with just LSM/YSZ material combinations, a reasonably efficient SOFC system could have been engineered many years ago if the demand was there. In my view, DOE has almost singlehandedly created the demand that we see now. Accumetrics is one of the handful of companies that DOE has funded to pursue this technology. Without DOE's investment, I doubt that private industry would be seriously looking at it today. Just my opinion though.
Actually, it can, but you need to gasify the coal first to create syngas (steam + coal --> CO + H2). Both CO and H2 can be oxidized in a solid-oxide fuel cell. There is a lot of research being done in these areas by the USDOE. I've worked on both SOFC (wrote a CFD model for SOFCs) and gasification (writing a CFD model model for fluidized bed gasification reactors). The "Next-Gen" power plant designs basically take in coal, gasify it, run it through a fuel cell, burn the effluent gas, run it through a turbine topping cycle, and finally separate out the CO2 and sequester it. The overall system efficiencies are quite good and can produce industrial CO2. There is more information here:
A solar cell is not a heat engine. It has no definable temperature difference, hence it has no Carnot efficiency limit. In thermodynamic terms, a solar cell is a direct energy conversion device, so Carnot limits do not apply. The same is true of fuel cells. The theoretical conversion efficiency of both are 100%. Reality is of course well below that. The key thing to note is that in their idealized form, there is no entropy production and hence no inefficiencies in the heat engine sense.
I don't see these as insurmountable problems. Making stealthy diamond-shaped radiators and solar panels seems tractable. This is DOD after all...it might be suboptimal and weigh five times as much as a regular design, but once it is in orbit, who cares? And I suspect the CIA or whoever is tasking those bird has access to the NORAD orbit tracking data so they know how to fly around everything else up there.
...which are likely left as decoys for the other dozen or so invisible ones...the reconnaissance version of a honeypot. The US has had stealth technology for a long time...aerodynamics is what took so long to build the F117. Since aerodynamics doesn't matter in space, I think it is likely that the satellites put up in the 70s where probably stealthy. Highly directional, bursty, spread spectrum downlinks would make it very difficult to detect. Again, that's 70s-era technology.
The $500 billion dollar annual defense budget is being spent somewhere. I would hope some of it was put into spy satellites that are awful easy to overlook.
I believe that the height of the carpet of the nanotubes on the electrodes is going to be small relative to the thickness of the dielectric material between the electrodes. That dielectric thickness is the limiting factor for typical capacitors. The dielectric can only be so thin before it can no longer prevent current flow, maintain mechanical integrity, etc. Otherwise, you could store unlimited energy in a capacitor by making the dielectric thinner and thinner. With these, the dielectric thickness can stay the same, but the surface area on each electrode can be much higher. That is like making a physically bigger capacitor.
The key word for the airfoil problem is "conformal mapping." It is a technique used to map 2D space into the complex domain and in the process manipulated its shape. So what was a sphere or straight line segment is now an airfoil. It is used to make the solution of "potential flow" possible, so called because the velocity field of the flow is generated by the gradient of a single scalar potential.
My firewall at home is a Celeron 300a that has been overclocked to 450 MHz since I built it. It has been running 24-7 for at least 7 or 8 years. It's spent most of that time crunching on something...either SETI or one of my CFD codes.
OK, I have a question for those M.D. types about. Has anyone investitaged the possibility of breaking virus by hitting them with carefully tuned chorus of electromagnetic (and/or ultrasonic) waves? If they can build up a 3D model of the thing, then they can identify vibrational modes in the virus structure, right? If you can catalog several of these modes and expose infected tissue to EM waves that will excite vibrations at those frequencies, it seems natural to think that you could literally shatter the virus mechanically. By using many different frequencies, damage to other benign cells and structures could be avoided as all of the driven frequencies would dump energy into the virus' protein sheath. Other cells might only have a resonance close to one of the frequencies and not absorb much energy.
I've long since wondered if this could work. Maybe the differing composition of the human body would complicate things or maybe the frequencies involved would be too readily absorbed by other tissues. Just thought I'd ask.
I've thought the same. I have racks of single core 3.0 GHz Xeons that strain the memory bus to the limit. Adding more cores to that mix is a waste. So, the new cluster is dual-core AMDs. The Intel architecture is generally good for the codes that we run, but I couldn't justify not buying AMDs. Price, thermal footprint, and performance all went that way.
Protip to Intel: Stop trying to feed your users this crap.
Slashdot Mirror
Nitrogen can't exist as a gas at a given temperature and arbitrarily high pressure. Read about phase transitions. Liquid nitrogen is about 0.8 the density of water. If you try to squeeze it to make it neutrally buoyant, it will liquefy before it gets to the density of water.
Um, how do you intend to keep bags of air at any depth underwater? Even when highly compressed, the density ratio is going to cause buoyancy, requiring some anchoring mechanism and a bag that is structurally sound enough to handle the stresses. I don't think that you can compress air enough to get it to match the density of liquid water at any depth...the nitrogen will start to liquefy first...and that brings a whole different set of problems.
Um, 50 gigawatt hours is about 1.8 * 10^14 joules. That is about 43 kilotons of energy. Now think catastrophic failure. Here is an example 1/10 the size.
All energy storage systems...especially physical storage systems...suffer from the same problem. In order to store a useful amount of energy, they need to exist on a potentially catastrophic scale. Pump storage...where is the flood plane. Compressed air...what is the blast radius, where will the supercooled plume go, will it reach aviation altitudes? Flywheel storage...reference mythbusters with the CD on a die grinder. And while not a storage system, even geothermal power plants seem to cause geological instability.
A few years ago, I did some modelling development for people doing salt mining for compressed air storage. (IAAMechEngineer.) At the time, I remember thinking what must the hoop stresses on a 100m cavern look like at a few hundred atmospheres? And that is rock and dirt and salt holding it together. Nothing in that system tends to behave elastically. So pressurizing and depressurizing it has to induce crack growth and eventually some geological instability. How do you do in-situ inspection of your "pressure vessel"?
In my mind, some electrochemical process is far safer, even if it uses nasty chemical. Because you can keep the chemical apart (with 100-ft high berms if need be) until it is time to react them.
I can't wait for this newest bubble to burst. Thin clients haven't really been embraced for office apps where 95% of the functionality can run in the browser and it will work reasonably well. How can you expect to compete with native apps on PCs where performance is cheaply had so long as you don't need to run at the highest settings...or on consoles which look almost as good? The problem for game companies is that many folks have realized that they can play year old games on cheap new hardware to great effect...after the game is reduced to 50%.
I don't see the market niche. Hardcore gamers won't touch it. Casual gamers will baulk at the $15/month by in BEFORE you get the privilege to buy/rent a game. So, who will want this unless the games are steeply discounted? $180/year could be well spent on local hardware upgrades.
http://cipherdyne.org/fwknop/
This was posted above. It accomplishes the same goal as port knocking, but removes all of the timing issues and replay attack vectors. All of the communication is cryptographically signed and encrypted and done via a closed port.
I agree completely. We use fwknop as a part of a required two-factor authorization scheme for a US Government customer. It is a minor inconvenience to use it to open the ssh port before connecting, but it virtually eliminates attack attempts. How can you hack a closed port?
What you are describing already has been explored in various forms. These cells are essentially batteries, but when the are run down, they are "recharged" by flushing them with fuel to reduce the oxides back to a reactive state. I forget what they are called, but they have been tried. There are LOTS of ways to make fuel cells. Any 1st semester chem book tells you how to find the electrical potential of a given reaction. The problem is trying to make something robust, efficient, and stable.
Expensive to install. Reliability is a huge concern because they are ceramic and hence naturally brittle. But they also have rather large temperature gradients in them (part of what I was studying). Those gradients produces thermal stress which could really shorten the life of these things...you are talking about electrodes and electrolytes with thickness measured in 10s of microns, being heated by activation and ohmic losses on the inside, and cooled by reactant flows on the outside. Reliability, especially under transient loads, used to be a real concern. I'm sure that they have worked around many of the problems, either with careful control logic or special materials or both.
Also, sealing these things was a real PITA too. Leaks from one reactant stream into the other turned the fuel cell into a combustor. There were other problems...someone above mentioned sulfer poisoning, so the syngas or whatever needs to be scrubbed. Also, ion migration was a problem. Due to the high temperature, the various ions in the electrodes and catalysts could redistribute themselves, not unlike what can happen in ICs that are run too hot or at too high a voltage.
It is a new technology. DOE dumped a ton of money into research under the SECA program about 8-10 years ago. Their target was development of these little component units that could be deployed a few at a time or ganged together into a massively parallel power plant configuration. I'm glad to see someone at least got something out to market.
These are solid oxide fuel cells (SOFCs). The catalyst is probably a little bit of nickel or some other fairly abundant metal. Platinum and/or palladium are needed as catalysts only for low temperature polymer electrolyte membrane (PEM) fuel cells.
Also, PEM fuel cells can be poisoned by carbon in the fuel stream. SOFCs can pretty easily oxidize CO and H2 and possibly even CH4 or C2H6 due to water-gas shift reactions.
IAA Mech Eng. I spent six years writing software to model both kinds of fuel cells.
The Google presentation noted above discusses the triple product and shows to be much closer to break-even than IEC and think a bit better than the Tokamak.
Your point about carbon neutrality is valid, but there is a reason for the pursuit of a safe, inexpensive hydrogen storage system. The PEM fuel cells that car manufacturers have been developing do not respond well to exposure to any hydrocarbon (except methanol). The short story is that carbon compounds foul the catalysts and ruin the fuel cell performance. For these systems, it would be ideal to feed them pure hydrogen from a storage tank. The other alternative is reform some hydrocarbon into hydrogen gas on the fly. That requires more energy and more equipment (more weight both for the reformer and for the carbon in the fuel that can't be used) and ultimate impacts the operational efficiency of the car. Pure hydrogen fuel makes the fuel cell system much lighter, cheaper, and easier to design and manufacture. The production of the pure H2 can be moved off to stationary reformer/production facilities.
So this is great news. I have long been skeptical about the feasibility of fuel cell cars with hydrogen storage being one of my main concerns. This new approach has the potential to remove it from my list. Of course, you still have the hydrogen production problem (what is the end-to-end efficiency?), the freezing problem (PEMs have hydrated membranes and water freezes), and the catalyst problem (how much platinum and palladium is there in the world?)
OK, if you actually programmed vector processors, you'd know that the current CPU development is largely heading in the direction of vector processing--not with multicores, but with SSE4/altivec/MMX and especially with GPUGP. The approaches for making most common numerical algorithms work well on vector CPUs were sorted out on the original Cray machines in the 80s.
One question that both AMD and Intel are asking is the target application for more CPU. Intel has their pet ray-tracing app, etc. For encoding/decoding video, numerical simulations, etc., there is excellent evidence that wide SIMD vector-type operations can give dramatic performance increases...see the aforementioned GPUGP. What Intel/AMD may decide is that more real world performance can be found by limiting core count and provide 8-wide or 16-wide SIMD instructions and allow the 20-year-old vectorizing compiler techniques to exploit that parallelism. Four cores with 16-wide SIMD instructions is probably far better than 16 cores with 4-wide SIMDs.
The analogous situation currently exists with small propane tanks for gas grills, etc. There are dozens of places that have racks of these ready to swap with your old one. I think this is an excellent business model. Each location will need to an inventory of batteries that is equal to the peak turn-over rate times the recharge time plus a bit of a cushion. The trick is getting automakers first to build electric cars at all and second to agree on a standard battery module.
He claims that this is equivalent to the Carnot cycle...specifically it is an Ericsson cycle. It still has the same (low) fundamental efficiency for small temperature differences. This is unlike a fuel cell which is not a heat engine and the Carnot limit doesn't apply. His target application is solar concentrators so the temperature difference would be much higher.
The problems with SOFCs are numerous. First, they are ceramic so they are brittle. So, they need to run at a more-or-less constant and uniform operating temperature. Thermal gradients in the system lead to differential expansion and thermal stress. Placing a ceramic in tension is a good way to find out that you need to buy a new ceramic.
Second problem is sealing. You need to build stacks of cells in order to get a decent operating voltage out of the system. This requires a sandwiching scheme of some type...there are different approaches, all with their own drawbacks. But sandwiching always leads to the possibility of leaks between cells...fuel in the air stream or vice versa and you no longer have a fuel cell--you have a combustor. These things operate at 800-1000 C, the normal sealing technologies are not useful.
Another problem is ionic migration. Things you uses in seals or supports or electrical or thermal management can all allow ions to migrate into the electrochemically active part of the cell and that can poison the system. Or the catalyst that is necessary to allow the electrochemical reactions can migrate away from the three-phase boundaries and reduce efficiency.
Another problem is ohmic losses. The current carrying parts of the cell are doped ceramics. These are not the most electrically conductive materials, so ohmic losses (and the resultant heating) can be a problem.
Just building the things is a problem. You have two different ceramic compounds with two different coefficients of thermal expansion. They have to be sintered together somehow. The layers need to be very thin to cut down ohmic and diffusion losses. And electrolyte needs to not leak. Making all of this work is something of a black art. Most test cells are only a few square inches. Scaling production up so that you can get a planar cell that something like a 1 ft on a side is still a daunting task. I think the folks doing tubular cells (including Accumetrics) may have an easier time of this, but again, they have there own manufacturing issues.
If you run the cell on anything but pure H2, you run the risk of coking the thing up. These are porous ceramic parts with lots of tiny passages through which reactants must diffuse. If you get the conditions wrong, atomic carbon can precipitate and plug the thing up.
I could go on and on.
Honestly, there hasn't been much interest in SOFCs until maybe six or seven years ago. Only a handful of companies have pursued the technology. There are still advances to be made in material science and material processing, but I think even with just LSM/YSZ material combinations, a reasonably efficient SOFC system could have been engineered many years ago if the demand was there. In my view, DOE has almost singlehandedly created the demand that we see now. Accumetrics is one of the handful of companies that DOE has funded to pursue this technology. Without DOE's investment, I doubt that private industry would be seriously looking at it today. Just my opinion though.
I didn't say there were no inefficiencies. Indeed there are many. I said that the Carnot efficiency analysis for heat engines was not appropriate.
Actually, it can, but you need to gasify the coal first to create syngas (steam + coal --> CO + H2). Both CO and H2 can be oxidized in a solid-oxide fuel cell. There is a lot of research being done in these areas by the USDOE. I've worked on both SOFC (wrote a CFD model for SOFCs) and gasification (writing a CFD model model for fluidized bed gasification reactors). The "Next-Gen" power plant designs basically take in coal, gasify it, run it through a fuel cell, burn the effluent gas, run it through a turbine topping cycle, and finally separate out the CO2 and sequester it. The overall system efficiencies are quite good and can produce industrial CO2. There is more information here:
s /vision21/
http://www.fossil.energy.gov/programs/powersystem
A solar cell is not a heat engine. It has no definable temperature difference, hence it has no Carnot efficiency limit. In thermodynamic terms, a solar cell is a direct energy conversion device, so Carnot limits do not apply. The same is true of fuel cells. The theoretical conversion efficiency of both are 100%. Reality is of course well below that. The key thing to note is that in their idealized form, there is no entropy production and hence no inefficiencies in the heat engine sense.
Yes, I am a mechanical engineer.
I don't see these as insurmountable problems. Making stealthy diamond-shaped radiators and solar panels seems tractable. This is DOD after all...it might be suboptimal and weigh five times as much as a regular design, but once it is in orbit, who cares? And I suspect the CIA or whoever is tasking those bird has access to the NORAD orbit tracking data so they know how to fly around everything else up there.
...which are likely left as decoys for the other dozen or so invisible ones...the reconnaissance version of a honeypot. The US has had stealth technology for a long time...aerodynamics is what took so long to build the F117. Since aerodynamics doesn't matter in space, I think it is likely that the satellites put up in the 70s where probably stealthy. Highly directional, bursty, spread spectrum downlinks would make it very difficult to detect. Again, that's 70s-era technology.
The $500 billion dollar annual defense budget is being spent somewhere. I would hope some of it was put into spy satellites that are awful easy to overlook.
I believe that the height of the carpet of the nanotubes on the electrodes is going to be small relative to the thickness of the dielectric material between the electrodes. That dielectric thickness is the limiting factor for typical capacitors. The dielectric can only be so thin before it can no longer prevent current flow, maintain mechanical integrity, etc. Otherwise, you could store unlimited energy in a capacitor by making the dielectric thinner and thinner. With these, the dielectric thickness can stay the same, but the surface area on each electrode can be much higher. That is like making a physically bigger capacitor.
The key word for the airfoil problem is "conformal mapping." It is a technique used to map 2D space into the complex domain and in the process manipulated its shape. So what was a sphere or straight line segment is now an airfoil. It is used to make the solution of "potential flow" possible, so called because the velocity field of the flow is generated by the gradient of a single scalar potential.
My firewall at home is a Celeron 300a that has been overclocked to 450 MHz since I built it. It has been running 24-7 for at least 7 or 8 years. It's spent most of that time crunching on something...either SETI or one of my CFD codes.
OK, I have a question for those M.D. types about. Has anyone investitaged the possibility of breaking virus by hitting them with carefully tuned chorus of electromagnetic (and/or ultrasonic) waves? If they can build up a 3D model of the thing, then they can identify vibrational modes in the virus structure, right? If you can catalog several of these modes and expose infected tissue to EM waves that will excite vibrations at those frequencies, it seems natural to think that you could literally shatter the virus mechanically. By using many different frequencies, damage to other benign cells and structures could be avoided as all of the driven frequencies would dump energy into the virus' protein sheath. Other cells might only have a resonance close to one of the frequencies and not absorb much energy.
I've long since wondered if this could work. Maybe the differing composition of the human body would complicate things or maybe the frequencies involved would be too readily absorbed by other tissues. Just thought I'd ask.
I've thought the same. I have racks of single core 3.0 GHz Xeons that strain the memory bus to the limit. Adding more cores to that mix is a waste. So, the new cluster is dual-core AMDs. The Intel architecture is generally good for the codes that we run, but I couldn't justify not buying AMDs. Price, thermal footprint, and performance all went that way.
Protip to Intel: Stop trying to feed your users this crap.