"It dissipates heat at an exponential rate, it's beyond belief, and I have no idea why it does, all I know is that it does."
He probably doesn't know what hes talking about. "Disspates heat" probably means "The other side from the fire doesnt get hot" and "exponentially" probably means "really good".
What it probably really is is a substance with low conductivity that retains its integrity at high temps. Or something. Frankly, there's lots of those around. Like for example, bricks which also start out life as paste. Where it may be interesting is how it gets cured (if it does) and what kind or structural properties it has in that state (ductility, strength). The fact that he talks about "spraying it *off*" makes me wonder what kind of stuff it is.
The GPL doesn't explicitly mention static or dynamic linking. Is it conventional wisdom that static linking produces a work based on the Program, while linking to a shared lib doesn't?
One thing about this book is the high profile given to Leo Szillard, who actually patented nuclear fission. I'd never heard of him before I read it.
He was quite a bon-vivant apparently, disarming people with his "Szillardian tales".
Both vehicles have airlocks, thats all they would need. The problem would have been getting the orbiter into the ISS orbit wich likely would have taken more propellant than they had.
WRT the other reply, belive it or not, there are people in the world who are qualified to have opinions. Some of us are fed up with NASA. NASA has had 30 years to develop the next generation of space transportation and they have gone nowhere. NASP, X-33, X-34 were all cancelled for no obvious reasons, leading to the conclusion that politics and not technology are driving the decisions.
The shuttle should really be classified as an X vehicle given its reliability rating, but if that were the case only test pilots would be permitted to fly and operations would be impossible. Commercial aircraft must have a failure rate of 1E-9 per flight hour, the STS is about a million times higher.
I wouldn't want to be the one to try to convince to the children of the dead men and women that making kids grow up without parents is a risk the shuttle program is willing to take. Did the original spec for the STS say heros only would be allowed abord?
Well, they are heros now, whether they wanted to be or not.
When I first heard the news I could think of three things that could have caused this. A guidance system failure, a structural failure, and a failure in the thermal protection system. Then, when I heard about the communications with the ground it seemed clear the first two were ruled out. I'm sure it was the tiles, though not court-sure for the moment.
If NASA is saying they didn't see it as a problem because tile damage had happened before and didn't cause a catastrophe, they they are in big trouble. You don't run a program like the STS by feeling your way along. You predict based on hard data and analysis and if you don't have the data you do a research program to get it.
Lets recall that the Challenger failure resulted from a well known phenomenon in the SRB field joints. Several qualified individuals knew what was going to happen to Challenger.
NASA's culture has changed since then, sure. But, it's still funded by politics. Serious observers know the best risk analysis puts the loss rate of shuttles at.5% per mission...and yet, a new educator in space mission was being planned. Something obviously has become disconnected with that program, again.
And this isn't all pointless to speculate about. *Maybe* if they had done a proper analysis of the tile damage (if thats what it was), they could have dropped most of the crew off at the ISS.
I like the way it flies neatly over the guy in blue jeans. You can see him just at the end of the clip. I can't tell looking at the clip if he's mission control or just some guy having a barbeque. My compliments to the Oklahoma Spaceport's range safety officer.
Its called an auto-gyro. Idea's been around for years. I guess Cartercopter sounds better or maybe its just an ego thing. Anyway, its not a bad idea, but not a new one either. The problem is, auto-gyros can't hover, although they have short take-offs and almost vertical landings.
The great thing about AG's is the simplicity of the drive train. The probem that plagues all choppers is where to put the engine and how to get the power to the rotors. Probably the most common solution is to put the engine on the roof (like most of Bell's line, which minimizes the drive train length, but then, well, you have an engine on the roof, creating a lot of drag and looking stupid. Some put it behind the cabin (a la MD helicopters , which is great drag-wise and looks groovy, but then you get a gear box about 4 inches from the back passengers ear plus a long drive shaft from behind the passengers up to the roof. Its nightmarish.
To really get my sympathy JYW teams should only be allowed to work with a crowbar, a garden trowel, and a pair of pliars they can only use as a hammer. Then I could relate.
That interference grid idea answers a question I was thinking about namely: the wavelength of visible light is 400-700nm which is bigger than nano-size, so how can a nano-thingy have any colour at all? But, ah, wouldn't the grid *absorb* a certain colour rather than reflect it? Anyways. And about the self-repairing silliness: there are 2 ways of fixing cracks...buffing them out and welding them (broadly speaking). If you buff, what happens to the swath (the removed metal dust)? It just builds up under the paint? And how does the paint know a crack is a crack and not a normal joint in the metal, or the lip between a rivet head and the sheet. Etc etc. I wish I could work on something like this.
Speaking of aviation:
This SAAB Gripen crash was attributed to the coding of the control laws in the flight control computer. So was this one. And this F-22. And lets all remember the Apollo 11 incident.
Rockets blow up because physics says they just barely work. Unless you trim every last gram of excess weight off the propulsion system and structure you just can't get into orbit. At take-off they are more or less 89% fuel, 10% structure, and 1% payload (typical numbers for the shuttle). So even if you gave up all your payload to strengthen the structure, you wouldn't be able to make it perceptibly stronger and safer.
The problem is that you need go up 200 miles and at the same time accelerate to 25000 mph.
I've always said if NASA would just stop spending money on shuttle ops and spend it instead on developing air-breathing alternatives it would make so much sense. A scram-jet based orbiter would get it's oxidizer from the atmosphere so would have to carry half as much fuel (roughly speaking). The weight savings can go to payload and more robust structure.
The notation they are using is (resin-type/fiber-type)subscript-number-of-layers so ((PEI/PAA)(PEI/SWNT)5)8 means one layer of polyethyleneimine and polyacrylic acid followed by 5 layers of PEI and Single Wall Nano Tubes with the whole shebang repeated 8 times for a total of 48 layers.
Checking out the stress-strain curves, the peak is around 160 MPa. A typical modern graphite composite might give you 4 or 5 times higher than that. It just goes to show that high fiber properties are just a portion of the final composite strength.
Another thing I notice about the stress strain curves is the non-linearity. It looks like there is some internal damage maybe happening in the material before failure. This is a concern for repeated loading (fatigue).
Right on. In comparison to other structural materials, glass is acually quite flexible (low modulus). Fiberglass airplanes tend to be limited by flexibility, that is, the designer has to put in enough material to prevent the wings (for example) from bending too much to prevent them from doing their aerodynamic job.
Graphite composite structures tend to be limited by static strength (ie they will break before they deform too much) and metallics are limited by fatigue strength.
Glass fibers actually have a very high strength but most of the time you cant use it all because of the felxibility. Graphite was going to replace aluminum in airplanes until we found out its vulnerable to impact damage (though that's changing with newer resins). Kevalar was going to change the world until we found out it has no compression strength (I once had to certify a Kevlar wing on a surveillance drone: Kevlar is like designing with chain...you can pull on it but don't push).
I'm sure eventually the pro's and cons of this new stuff will come out. Personally I'd like to know about it's damage tolerance.
Those zero-cte struts Boeing made use fiberous composites. Unidirectional composites expand 'normally' with increasing temperature in the fiber direction but contract in the other direction because of the poisson's effect. A multi-ply laminate with the fibers in each ply at a certain angle to the principle direction gives a nil cte in that direction, but not any other.
That's completely different from a monolithic isotropic material thats got negative cte in all directions.
First of all, no I don't like that fact that the video store knows I rented Prison Guard Vixens VIII. Remember Clarence Thomas? Some video store let it slip that he had rented some porn video when he was up for the supreme court nomination. I bet their policy says that can never happen. So for consistency's sake consider my complaint about that lodged too.
The ethical issue, as I said, is that if everyone did what they do, the net wouldn't work. NYT gets away with it because they have good content so the annoyance is worth it. What if CNN, ABC News, CBS News, LinuxToday, Slashdot, Google, NASA.gov and so on and so on required registration just to look at their site? There would be a mass throwing of hands up and everyone would just go watch TV. So, they get away with it (and get an advantage in the form of marketing data) because everyone else refrains. That's an ethical question.
Mmm. Theres no need to register with/. if you don't want to. You can read and post anonymously.
Doesn't it bug you to tell some stranger about yourself for no reason? When you walk into the shopping mall, is there someone standing at the door telling you you can't come in unless you tell them your salary? Then do they have someone follow you around with a clipboard writing down what stores you look in? Wouldn't that creep you out just a little bit?
Why doesnt every.com web site do the same thing as the NYT? Couldn't every business use some marketing data? There's absolutely nothing stopping everyone from doing that, except most web site owners know it would drive users away from the web in droves. So it's really an unspoken social contract.
Like, when the traffic is backed up in the exit lane on the freeway, then some maniac zooms up on the left and cuts in. It's not illegal if he doesnt cross a solid line, but most people don't do it because they know if most people did it no one would ever get anywhere. It's a collective unspoken social agreement and anyone who breaks the rule becomes an outcast (f@#&ing a@@hole in the traffic example), so that's why the NYT is so annoying.
In Big Band New Moon Robin Canup describes how the moon might have been formed by a gigantic impact. In that scenario a ring of ejecta was formed but didn't last long...perhaps a hundred years.
Slashdot Mirror
The idea of overpayment is an issue only if there is inequity.
One American individual (guess who) is worth as much as the bottom 40% of the population (120 million people).
The top 1% of the American population has more wealth than the bottom 95%.
"It dissipates heat at an exponential rate, it's beyond belief, and I have no idea why it does, all I know is that it does." He probably doesn't know what hes talking about. "Disspates heat" probably means "The other side from the fire doesnt get hot" and "exponentially" probably means "really good". What it probably really is is a substance with low conductivity that retains its integrity at high temps. Or something. Frankly, there's lots of those around. Like for example, bricks which also start out life as paste. Where it may be interesting is how it gets cured (if it does) and what kind or structural properties it has in that state (ductility, strength). The fact that he talks about "spraying it *off*" makes me wonder what kind of stuff it is.
Epoxy cures by a chemical reaction when a diepoxy and diamine are mixed together. It doesn't need oxygen from the air.
Re: "this continent" Not necessarily: Da Vinci and Canadian Arrow
The GPL doesn't explicitly mention static or dynamic linking. Is it conventional wisdom that static linking produces a work based on the Program, while linking to a shared lib doesn't?
One thing about this book is the high profile given to Leo Szillard, who actually patented nuclear fission. I'd never heard of him before I read it. He was quite a bon-vivant apparently, disarming people with his "Szillardian tales".
WRT the other reply, belive it or not, there are people in the world who are qualified to have opinions. Some of us are fed up with NASA. NASA has had 30 years to develop the next generation of space transportation and they have gone nowhere. NASP, X-33, X-34 were all cancelled for no obvious reasons, leading to the conclusion that politics and not technology are driving the decisions.
The shuttle should really be classified as an X vehicle given its reliability rating, but if that were the case only test pilots would be permitted to fly and operations would be impossible. Commercial aircraft must have a failure rate of 1E-9 per flight hour, the STS is about a million times higher.
I wouldn't want to be the one to try to convince to the children of the dead men and women that making kids grow up without parents is a risk the shuttle program is willing to take. Did the original spec for the STS say heros only would be allowed abord?
Well, they are heros now, whether they wanted to be or not.
When I first heard the news I could think of three things that could have caused this. A guidance system failure, a structural failure, and a failure in the thermal protection system. Then, when I heard about the communications with the ground it seemed clear the first two were ruled out. I'm sure it was the tiles, though not court-sure for the moment. If NASA is saying they didn't see it as a problem because tile damage had happened before and didn't cause a catastrophe, they they are in big trouble. You don't run a program like the STS by feeling your way along. You predict based on hard data and analysis and if you don't have the data you do a research program to get it. Lets recall that the Challenger failure resulted from a well known phenomenon in the SRB field joints. Several qualified individuals knew what was going to happen to Challenger. NASA's culture has changed since then, sure. But, it's still funded by politics. Serious observers know the best risk analysis puts the loss rate of shuttles at .5% per mission...and yet, a new educator in space mission was being planned. Something obviously has become disconnected with that program, again.
And this isn't all pointless to speculate about. *Maybe* if they had done a proper analysis of the tile damage (if thats what it was), they could have dropped most of the crew off at the ISS.
If your business plan doesnt intersect with reality, then change reality. Lots of luck to them.
I like the way it flies neatly over the guy in blue jeans. You can see him just at the end of the clip. I can't tell looking at the clip if he's mission control or just some guy having a barbeque. My compliments to the Oklahoma Spaceport's range safety officer.
The great thing about AG's is the simplicity of the drive train. The probem that plagues all choppers is where to put the engine and how to get the power to the rotors. Probably the most common solution is to put the engine on the roof (like most of Bell's line, which minimizes the drive train length, but then, well, you have an engine on the roof, creating a lot of drag and looking stupid. Some put it behind the cabin (a la MD helicopters , which is great drag-wise and looks groovy, but then you get a gear box about 4 inches from the back passengers ear plus a long drive shaft from behind the passengers up to the roof. Its nightmarish.
I was going to write something but I got bored halfway through so I wrote this instead.
To really get my sympathy JYW teams should only be allowed to work with a crowbar, a garden trowel, and a pair of pliars they can only use as a hammer. Then I could relate.
That interference grid idea answers a question I was thinking about namely: the wavelength of visible light is 400-700nm which is bigger than nano-size, so how can a nano-thingy have any colour at all? But, ah, wouldn't the grid *absorb* a certain colour rather than reflect it? Anyways. And about the self-repairing silliness: there are 2 ways of fixing cracks...buffing them out and welding them (broadly speaking). If you buff, what happens to the swath (the removed metal dust)? It just builds up under the paint? And how does the paint know a crack is a crack and not a normal joint in the metal, or the lip between a rivet head and the sheet. Etc etc. I wish I could work on something like this.
New Requisition for: 143,000,000,000 nanotech machine mechanics.
Speaking of aviation: This SAAB Gripen crash was attributed to the coding of the control laws in the flight control computer. So was this one. And this F-22. And lets all remember the Apollo 11 incident.
The problem is that you need go up 200 miles and at the same time accelerate to 25000 mph.
I've always said if NASA would just stop spending money on shuttle ops and spend it instead on developing air-breathing alternatives it would make so much sense. A scram-jet based orbiter would get it's oxidizer from the atmosphere so would have to carry half as much fuel (roughly speaking). The weight savings can go to payload and more robust structure.
Checking out the stress-strain curves, the peak is around 160 MPa. A typical modern graphite composite might give you 4 or 5 times higher than that. It just goes to show that high fiber properties are just a portion of the final composite strength.
Another thing I notice about the stress strain curves is the non-linearity. It looks like there is some internal damage maybe happening in the material before failure. This is a concern for repeated loading (fatigue).
Graphite composite structures tend to be limited by static strength (ie they will break before they deform too much) and metallics are limited by fatigue strength.
Glass fibers actually have a very high strength but most of the time you cant use it all because of the felxibility. Graphite was going to replace aluminum in airplanes until we found out its vulnerable to impact damage (though that's changing with newer resins). Kevalar was going to change the world until we found out it has no compression strength (I once had to certify a Kevlar wing on a surveillance drone: Kevlar is like designing with chain...you can pull on it but don't push).
I'm sure eventually the pro's and cons of this new stuff will come out. Personally I'd like to know about it's damage tolerance.
That's completely different from a monolithic isotropic material thats got negative cte in all directions.
Oh crud...make that Robert Bork.
The ethical issue, as I said, is that if everyone did what they do, the net wouldn't work. NYT gets away with it because they have good content so the annoyance is worth it. What if CNN, ABC News, CBS News, LinuxToday, Slashdot, Google, NASA.gov and so on and so on required registration just to look at their site? There would be a mass throwing of hands up and everyone would just go watch TV. So, they get away with it (and get an advantage in the form of marketing data) because everyone else refrains. That's an ethical question.
Doesn't it bug you to tell some stranger about yourself for no reason? When you walk into the shopping mall, is there someone standing at the door telling you you can't come in unless you tell them your salary? Then do they have someone follow you around with a clipboard writing down what stores you look in? Wouldn't that creep you out just a little bit?
Why doesnt every .com web site do the same thing as the NYT? Couldn't every business use some marketing data? There's absolutely nothing stopping everyone from doing that, except most web site owners know it would drive users away from the web in droves. So it's really an unspoken social contract.
Like, when the traffic is backed up in the exit lane on the freeway, then some maniac zooms up on the left and cuts in. It's not illegal if he doesnt cross a solid line, but most people don't do it because they know if most people did it no one would ever get anywhere. It's a collective unspoken social agreement and anyone who breaks the rule becomes an outcast (f@#&ing a@@hole in the traffic example), so that's why the NYT is so annoying.
In Big Band New Moon Robin Canup describes how the moon might have been formed by a gigantic impact. In that scenario a ring of ejecta was formed but didn't last long...perhaps a hundred years.
Couldnt you just use a dab of radium and a scintillation detector? Your random quantity would be the time between decay events.