You don't mention ipython, but I had a very similar problem making and closing plots when using ipython, but not when using straight python for the interactive session (or, obviously, in scripts). The problem is that ipython caches things it really shouldn't, like closed plots. Try setting the ipython "-cs" option to 0 and see if things improve.
The switch to metacity is precisely what triggered me to stop using Gnome. I know sawfish had development problems (eh - it worked for me), but switching to something that wouldn't let me move the toolbar off the top of the screen was a pain on my old 800x600 laptop. Then seeing that requests to fix that (even if just added back as an option) were referred to as "crack" convinced me Gnome and I had parted ways - I'm not just another dumb user and don't want to be treated as such. No hard feelings - they can do what they like with their code - I just stopped using Gnome.
I believe that the toolbar thing was eventually "fixed" due to complaints from disabled users that couldn't be ignored as "crack," but the Gnome philosophy is consistent (button order, nautilus opening new windows, now the printing dialog). I don't need to push my crack on others, but I want the option of turning the crack on for myself...
First, I agree with the above responses that ultimately the price doesn't matter; it's the principle.
But...
Second, I call BS on your $1.7 million average. I don't know where you get your data, but
this says they "budgeted $1.6 million to pay for the 15 homes."
Looking at the mass of wings (and possibly landing gear) and comparing that to adding the equivalent mass in fuel to a capsule design, the cross-range and lower-g advantages of wings aren't so apparent. The Lockheed people undoubtedly did a trade and found that for their mission assumptions the lifting body gave the best results, but change the assumptions (e.g., use higher ISP engines/fuel in RCS), and a straight capsule may be better.
Your original question, while not related to nuclear reactors (yep, they can't detonate), is a good one. The sun is very big, but very far away. A nuclear weapon up-close can exceed the sun's apparent output for a short time. The radiation from a weapon is different, too - there aren't any nuclear reactions at the sun's surface.
Not only that, but according to space.com, the mission is an orbiter, not a lander.
The US sent Clementine to the moon for $75 million dollars ten years ago. Chandrayan will be more capable, and I'm all for it, but this isn't exactly a revolution in lunar exploration.
For air the molecular weight is essentially constant with altitude (at 28.8, so R = 8314/28.8 = 287 J/(kg*K)). Perhaps you thought I was using R as the universal gas constant? Certainly for a fixed MW ideal gas (e.g., air) speed of sound is purely a function of temperature.
Gamma is ratio of specific heats (C_p/C_v), which can be approximated by the excited degrees of freedom, n, using gamma = (n+2)/n. Thus, for a diatomic species below the vibration excitation temperature (like air), gamma is about (5+2)/5 = 1.4. The characteristic vibrational temperature for O2 is a little over 2000 K and for N2 over 3000 K, so gamma=1.4 is pretty good in the atmosphere.
I said the equation is valid for an ideal gas, but to be more specific a=sqrt(gamma * R * T) requires caloric and thermal perfection. Calorically perfect means the internal energy is purely a function of temperature, while thermal perfection implies p = rho * R * T (again, gas specific R).
Why, yes, I do have a Ph.D. in this.;-)
References: NACA 1135 - Should be on every aerodynamicist's bookshelf Liepmann & Roshko - Elements of Gasdynamics Vincenti & Kruger - Physical Gas Dynamics
Actually, for an ideal gas (not a bad approximation for air), the speed of sound is purely a function of the temperature (a = sqrt(gamma * R * T)). Google on "speed sound altitude" gave this amusing link for the altitude variation:
Re:Let's just get this out of the way...
on
More on Global Dimming
·
· Score: 2, Informative
This is backwards. The sun is at around 6000 K, the earth averages around 300 K. It comes in short and goes out long (why IR absorbers like CO2 are good greenhouse gasses).
Re:Let's just get this out of the way...
on
More on Global Dimming
·
· Score: 4, Informative
Oversimplified...
The sun's energy output is strongest at visible wavelengths (peak power in the green - coincidence that chlorophyll is chemical of choice for providing energy to plants? I think not...). The earth absorbs a lot of this, but being much cooler than the sun, re-radiates it back out in the IR.
So, aerosols (including clouds) tend to scatter shorter wavelengths more but let the longer stuff through. Greenhouse gasses absorb the longer wavelengths, but let the shorter stuff through.
(we are after all partical physcists and not sys admins)
I agree - I don't think a qualified sysadmin would be compiling fixes from source when there are plenty of distributions with good binary package (and kernel) update mechanisms.
It's got all the thrust of an ion engine (i.e., almost none), but it only works in the atmosphere, where wind current is going to create a dynamic pressure which swamps out its thrust.
Ummm, it's a safe bet than when areas are involved, there's going to be a length squared somewhere in the calculation...
GigsVT has it right; assuming cone of half-angle "alpha" and height "r", the area of the base is PI*(tan(alpha)*r)^2. There's that pesky r^2. The base radius of the cone grows linearly with distance, therefore the area of the cone base grows with the square of the distance.
Now, scaling the irradiance with the cone base area is treating the waves as planar (when they're really spherical in the far-field), but assuming alpha is small, that's not a bad approximation.
This is an excellent optics reference. In particular, look at "Gaussian Beam Propagation/Beam Waist and Divergence". It's a different wavelength, but E&M is E&M.
Actually, 1/r^2 still applies with an antenna (in the far field), it's just that (oversimplification) the antenna "shoots out a cone" rather than spreading the power over 4 pi steradians.
Consider some of this guy's papers. I don't have a good web-accessible reference (try searching Journal of Propulsion and Power), but there has been some talk of lithium fuel-cells. An interesting thing about them is that the plane would start light and get heavier as it flew further, since the lithium is too expensive and environmentally questionable to just chuck the reacted stuff out the back. The idea does sound a little wacky, but the power density looks to be quite good.
Hydrogen has an extremely large flammability range. This means that you can have a relatively small amount of H2 mixed with air, or a relatively small amount of air mixed with H2, and the mixture still burns. Relative here means compared with hydrocarbons, particularly alkanes (methane, propane, octane, etc.).
Another thing is that H2-air detonates much more easily than a typical hydrocarbon-air mixture, meaning your explosion can be much more destructive.
The only hydrocarbon that competes with hydrogen in these matters is acetylene (C2H2), which is some pretty nasty stuff in its own right (have to store dissolved in acetone, etc.).
I have been using a scientific visualization package called OpenDX. It is a complicated, but very powerful tool, and well worth the effort to learn if you have piles of data to look at. The documentation is good, and the mailing list has been newbie friendly. I used PV-WAVE in grad school, and spent a long time afterwards looking for an open source alternative - this is it. The only real downside is that it is a Motif app.
It used to be IBM's Visualization Data Explorer; they made it an open source project a couple of years ago (wow - go IBM). Available on a variety of Unix/Linux platforms and Windows (if you run an X server). We have it on two Linux machines and two W2k machines (latter using Cygwin/XFree86-4.1.0); 3D hardware acceleration is supported on the Linux machines - and presumably on windows too if we shelled out the $$$ for a commercial X server.
Slashdot Mirror
You don't mention ipython, but I had a very similar problem making and closing plots when using ipython, but not when using straight python for the interactive session (or, obviously, in scripts). The problem is that ipython caches things it really shouldn't, like closed plots. Try setting the ipython "-cs" option to 0 and see if things improve.
http://www.northernlatitude.com/images/FEB02-sundo g_parks_hwy.jpg
The switch to metacity is precisely what triggered me to stop using Gnome. I know sawfish had development problems (eh - it worked for me), but switching to something that wouldn't let me move the toolbar off the top of the screen was a pain on my old 800x600 laptop. Then seeing that requests to fix that (even if just added back as an option) were referred to as "crack" convinced me Gnome and I had parted ways - I'm not just another dumb user and don't want to be treated as such. No hard feelings - they can do what they like with their code - I just stopped using Gnome.
I believe that the toolbar thing was eventually "fixed" due to complaints from disabled users that couldn't be ignored as "crack," but the Gnome philosophy is consistent (button order, nautilus opening new windows, now the printing dialog). I don't need to push my crack on others, but I want the option of turning the crack on for myself...
First, I agree with the above responses that ultimately the price doesn't matter; it's the principle.
But...
Second, I call BS on your $1.7 million average. I don't know where you get your data, but this says they "budgeted $1.6 million to pay for the 15 homes."
Looking at the mass of wings (and possibly landing gear) and comparing that to adding the equivalent mass in fuel to a capsule design, the cross-range and lower-g advantages of wings aren't so apparent. The Lockheed people undoubtedly did a trade and found that for their mission assumptions the lifting body gave the best results, but change the assumptions (e.g., use higher ISP engines/fuel in RCS), and a straight capsule may be better.
Your original question, while not related to nuclear reactors (yep, they can't detonate), is a good one. The sun is very big, but very far away. A nuclear weapon up-close can exceed the sun's apparent output for a short time. The radiation from a weapon is different, too - there aren't any nuclear reactions at the sun's surface.
Check this out for more info on what a nuclear blast in near space can do: http://science.howstuffworks.com/e-bomb2.htm/. People don't die, but computers do.
Not only that, but according to space.com, the mission is an orbiter, not a lander. The US sent Clementine to the moon for $75 million dollars ten years ago. Chandrayan will be more capable, and I'm all for it, but this isn't exactly a revolution in lunar exploration.
We're also forgetting about how things like "make tenure fast" (http://www.falstad.com/cite.html) affect the rankings.
Well, as long as we're being pedantic...
;-)
For air the molecular weight is essentially constant with altitude (at 28.8, so R = 8314/28.8 = 287 J/(kg*K)). Perhaps you thought I was using R as the universal gas constant? Certainly for a fixed MW ideal gas (e.g., air) speed of sound is purely a function of temperature.
Gamma is ratio of specific heats (C_p/C_v), which can be approximated by the excited degrees of freedom, n, using gamma = (n+2)/n. Thus, for a diatomic species below the vibration excitation temperature (like air), gamma is about (5+2)/5 = 1.4. The characteristic vibrational temperature for O2 is a little over 2000 K and for N2 over 3000 K, so gamma=1.4 is pretty good in the atmosphere.
I said the equation is valid for an ideal gas, but to be more specific a=sqrt(gamma * R * T) requires caloric and thermal perfection. Calorically perfect means the internal energy is purely a function of temperature, while thermal perfection implies p = rho * R * T (again, gas specific R).
Why, yes, I do have a Ph.D. in this.
References:
NACA 1135 - Should be on every aerodynamicist's bookshelf
Liepmann & Roshko - Elements of Gasdynamics
Vincenti & Kruger - Physical Gas Dynamics
Actually, for an ideal gas (not a bad approximation for air), the speed of sound is purely a function of the temperature (a = sqrt(gamma * R * T)). Google on "speed sound altitude" gave this amusing link for the altitude variation:
i .h tml
http://www.grc.nasa.gov/WWW/K-12/airplane/atmos
This is backwards. The sun is at around 6000 K, the earth averages around 300 K. It comes in short and goes out long (why IR absorbers like CO2 are good greenhouse gasses).
Oversimplified...
The sun's energy output is strongest at visible wavelengths (peak power in the green - coincidence that chlorophyll is chemical of choice for providing energy to plants? I think not...). The earth absorbs a lot of this, but being much cooler than the sun, re-radiates it back out in the IR.
So, aerosols (including clouds) tend to scatter shorter wavelengths more but let the longer stuff through. Greenhouse gasses absorb the longer wavelengths, but let the shorter stuff through.
Check out this for info on nptl and subversion. Re-compiling Berkeley DB without nptl support worked for me.
Read up on first sale doctrine. The EULA can't make you relinquish that right.
(we are after all partical physcists and not sys admins)
I agree - I don't think a qualified sysadmin would be compiling fixes from source when there are plenty of distributions with good binary package (and kernel) update mechanisms.
It's got all the thrust of an ion engine (i.e., almost none), but it only works in the atmosphere, where wind current is going to create a dynamic pressure which swamps out its thrust.
Very cool toy, but nothing more.
Ummm, it's a safe bet than when areas are involved, there's going to be a length squared somewhere in the calculation...
GigsVT has it right; assuming cone of half-angle "alpha" and height "r", the area of the base is PI*(tan(alpha)*r)^2. There's that pesky r^2. The base radius of the cone grows linearly with distance, therefore the area of the cone base grows with the square of the distance.
Now, scaling the irradiance with the cone base area is treating the waves as planar (when they're really spherical in the far-field), but assuming alpha is small, that's not a bad approximation.
This is an excellent optics reference. In particular, look at "Gaussian Beam Propagation/Beam Waist and Divergence". It's a different wavelength, but E&M is E&M.
Actually, 1/r^2 still applies with an antenna (in the far field), it's just that (oversimplification) the antenna "shoots out a cone" rather than spreading the power over 4 pi steradians.
According to the Bill Gates Net Worth Page they could hire him for over two hours with that kind of money...
Consider some of this guy's papers. I don't have a good web-accessible reference (try searching Journal of Propulsion and Power), but there has been some talk of lithium fuel-cells. An interesting thing about them is that the plane would start light and get heavier as it flew further, since the lithium is too expensive and environmentally questionable to just chuck the reacted stuff out the back. The idea does sound a little wacky, but the power density looks to be quite good.
Hydrogen has an extremely large flammability range. This means that you can have a relatively small amount of H2 mixed with air, or a relatively small amount of air mixed with H2, and the mixture still burns. Relative here means compared with hydrocarbons, particularly alkanes (methane, propane, octane, etc.).
Another thing is that H2-air detonates much more easily than a typical hydrocarbon-air mixture, meaning your explosion can be much more destructive.
The only hydrocarbon that competes with hydrogen in these matters is acetylene (C2H2), which is some pretty nasty stuff in its own right (have to store dissolved in acetone, etc.).
I have been using a scientific visualization package called OpenDX. It is a complicated, but very powerful tool, and well worth the effort to learn if you have piles of data to look at. The documentation is good, and the mailing list has been newbie friendly. I used PV-WAVE in grad school, and spent a long time afterwards looking for an open source alternative - this is it. The only real downside is that it is a Motif app.
It used to be IBM's Visualization Data Explorer; they made it an open source project a couple of years ago (wow - go IBM). Available on a variety of Unix/Linux platforms and Windows (if you run an X server). We have it on two Linux machines and two W2k machines (latter using Cygwin/XFree86-4.1.0); 3D hardware acceleration is supported on the Linux machines - and presumably on windows too if we shelled out the $$$ for a commercial X server.