The UN has got to be the most currupt buerocracy on the planet. They just had the biggest corruption scandal ever. Bigger than ENRON and WorldCom combined.
With the tsunami aid effort, they were mostly concerned with holding meetings in 5 star hotels while other people did the real work.
They also constantly bash israel without ever mentioning that the palestinean side is not exactly peaceful either.
And they have recently decided that what is happening in sudan is not genocide. I guess they will decide it was genocide after all when everybody is dead. Like they did in ruanda.
The UN should be dismantled or at least seriously reformed. They should not get any more responsibilities, since they are obviously unable to cope with the responsibilities they have in an ethical manner.
I guess they are not sure themselves how much they can reuse.
They have spent quite a lot of time and mass on the first stage to make it reusable. For example there is a mortar-deployed parachute on the first stage. But since this has never been done before, they are not sure in what shape the stage will be after the water landing.
In the best case, they will just have to replace some parts (ablative nozzle, interstage etc), refuel it and relaunch it. In the worst case they can only reuse the high value parts like the engine and the valves.
We will find out soon enough.
Why falcons are cheap..
on
Hondas in Space
·
· Score: 4, Informative
The reason falcons will be cheap is not because they use cheap components, but because they have a different approach than old defense contractors like boeing and lockheed.
In fact they use very high quality materials such as a titanium thrust frame in the first stage. But they can afford that because the first stage is reusable.
They also try to avoid any hazardous materials like explosive bolts and dangerous chemicals since that makes working with the rocket before launch much safer and thus cheaper. The falcon I is the first rocket that is allowed to fly without an explosive flight termination system because of redundant thrust termination systems. So there is no bomb on board.
Take a look at the falcon launch complex. It is basically just a simple concrete building and a flatbed truck. The satellite is integrated while the rocket is horizontal, so they do not need a huge building for satellite integration.
The launch control center is a truck trailer, so they only need one for all launch pads and do not have all that expensive computer hardware sitting around idle.
Now compare that with the launch complex for the boeing delta IV. There is a vertical integration building for fitting the payload, a huge umbilical tower and all kinds of facilities to handle the huge quantities of liquid hydrogen that the delta IV needs.
The only large rocket that has a comparably clean launch pad like the falcon is the russian/ukrainian Zenit (also used by Sea Launch), which is also the cheapest of its class.
The falcon I will also have a very benign launch environment for the payload. The amount of vibration is much lower than with other rockets since the falcon does not use solids. See the payload users guide for details.
Re:Python versus Plone/Zope
on
Two Books On Plone
·
· Score: 3, Informative
Zope page templates (ZPT) are quite cool. But you can use them without zope in a pure python program. And the persistence and undo offered by the ZODB (Zope object database) is also quite useful.
There are multiple backends available, and you can get really good performance and security by using the file system backend of the ZODB on top of reiser4.
Most of the performance problems of the plone/zope combo come from plone. So my advice as someone who had the misfortune to optimize a plone/zope based commercial website: take a good look at zope, but stay the hell away from plone.
Plone is an overdesigned piece of crap
on
Two Books On Plone
·
· Score: 4, Insightful
Zope is a nice application server, but not exactly fast. It has nice abstractions like acquisition to do very complex web applications with only a few lines of code.
Plone adds more layers of abstraction and makes the whole even slower. It is almost as if the plone designers read a book about advanced OO concepts and wanted to implement every single concept they just learned about in a single application.
The only way to get decent performance out of a plone/zope setup is to put a squid proxy in front of it, but that causes a lot of problems with dynamic content.
The documentation is also horrible. If you are lucky it is just incomplete and out of date, but in most cases there is none at all.
If you want to do a small application with less than one hit per second, go ahead. But for a big site: forget it.
"I guarantee you these 20 people use the labor of others a lot more than they use their own labor. Why do we always obsess over people who are supposedly the best at something?"
That is a typical thing to say for a communist.
Why is it that you have such problems with admitting that some individuals are more gifted than others?
And while you claim to despise individualism, you worship individuals like that mass murderer che guevara.
How dare they omit john backus? He invented fortran, which is still the most often used language for scientific calculations. And he pioneered functional programming.
He deserves to be on top of this list for this publication alone.
Re:The java generics system is a joke
on
Java 1.5 vs C#
·
· Score: 1
List in C# and ArrayList in java are both backed by arrays, so they should have the best performance if you don't want to add or remove elements from the middle of the list.
The only way to get good performance in java would be to use an int[].
Re:Limitations of Generics in Java.
on
Java 1.5 vs C#
·
· Score: 2, Informative
An anonymous inner class in java can only refer to final variables from the local scope. So you define a final array with one element to copy something out of the inner class context.
Re:Limitations of Generics in Java.
on
Java 1.5 vs C#
·
· Score: 1
Java has anonymous *classes* since 1.1. But that is not the same as anonymous methods. And C# 2.0 has real closures and none of the limitations of java inner classes. No need for the "final array of one element" hack, if you know what I mean.
The java generics system is a joke
on
Java 1.5 vs C#
·
· Score: 2, Insightful
The java generics system just saves typing and ensures type-safety for collections. But it does nothing about the problem of excessive boxing and unboxing that plagued java collection classes from 1.0 on.
For example if you have an ArrayList<Integer> in java, it internally uses an object[] to store the elements of the array. So everytime you write a new value to the ArrayList<Integer> by e.g. calling list.Add(i), a new object is allocated on the heap.
A List<int> in C# on the other hand uses an int[] internally, so adding or changing an element in the List<int> will result in no boxing/unboxing at all. A List will be just as fast as an int[] since the indexer method will be inlined.
The performance difference is dramatic: try creating an ArrayList<Integer>/List<int> and filling it with 1000000 numbers. The C# code will run 10 to 20 times faster, while the java version will use 20 bytes per Integer instead of 4 bytes per Integer like the C# version.
I am currently not at home, but if somebody is interested I will post a benchmark later.
Slight correction: the atlas ballon tanks are made from high quality stainless steel. Other than that you are correct. The atlas was an amazing design.
With all the needle jokes and condom comparisons one could get the impression that these inflatable modules are less rugged than the aluminium modules now used for the ISS.
This is not the case. They are made out of multiple layers of kevlar (the same stuff that bulletproof vests are made of). In tests with the NASA-designed transhab inflatable module they have proven to be much more resistant to space debris than aluminium hulls.
Also even if a particulary large piece of space debris should punch a hole in one of these modules, they are so big that there would be plenty of time to evacuate them before the pressure drops too much. A long-time station will probably also have a repair kit on board.
Third, the problem of space debris is particulary severe in low earth orbit. But in a higher earth orbit there is much less space debris, and the stuff that is there moves with much lower relative velocities. So from a space debris point of view low earth orbit is the absolute worst case. A station at an Earth/Moon lagrange point or in deep space would need little or no space debris protection.
Maybe that is why VRML and X3D were not successful. Storing binary data like 3D vector data and texture data in a text file and then compressing the text file to get acceptable file sizes is just plain stupid.
Binary storage for 3D data makes a lot more sense since it is more compact and easier to parse, and there are also standards such as the IEEE float and double standard.
But nowadays everything has got to be XML, even if it does not make any sense at all. XML is fine for configuration files and office documents, but for image and vector data it is just not the right tool.
High velocity sniper rifles have muzzle velocities of about 1000m/s. Worst-case space debris has velocities of 8000m/s, so it has 64 times as much energy per mass.
But it is not as bad as it sounds. First of all space debris is not designed to penetrate armor. Usually it is quite small stuff.
And when a piece of space debris hits the outer shell of your space station it instantly vaporizes. So the inner shells of your space station just have to cope with vapor.
The first space habitats will be in low earth orbit where the earth magnetosphere provides some protection from charged particle radiation from the sun and deep space.
And the bigelow designs will use water-filled bladders on the inside of the wall to provide additional radiation protection. If you want to go outside low earth orbit, just add more water.
For solar storms there will be a radiation shelter with very thick water walls.
Its the same kind of material that is used in bulletproof vests. But it is multilayered and much thicker. So of course it is micro-meteorite proof.
Tests with the NASA transhab design have shown that multi-layered inflatables are more resistant to space debris than aluminium hulls. That should come as no surprise since the materials involved have much more (mass specific) tensile strength than aluminium.
Have you ever seen a flak vest made from aluminium?
I think accidents will not be a big deal. People risk their lives for all kinds of crazy shit like climbing the mount everest, so why should they not be allowed to risk their lives to live in space?
Early aviation history is full of deadly accidents. And people have still continued to build and fly airplanes.
If some nanny state government like the peoples republic of california will outlaw private space flight, the development will simply move somewhere else. Even if private spaceflight is outlawed in the whole US, there are other countries in the world.
There is plenty of stuff that can be done better in space once the transportation costs go down. You have unlimited quantities of hard vacuum, free energy from the sun 24h a day, access to very low temperatures with a simple radiator and perfect isolation from the earth biosphere.
So everything that could be harmful to the biosphere, requires lots of energy, hard vacuum or cryogenic temperatures will be more economical in space once the transportation problem is solved.
The first thing will probably be stuff like genetic engineering and bioweapons research. Then there will be solar power satellites. And once you get these in place most of the heavy industry will move to space (high earth orbit, to be precise).
Just think about the advantages: you can build a huge industrial complex without people suing you about the noise, the pollution etc.
There are plenty of people developing new space transports. Most notably spacex. But there are many more such as the mysterious Blue Origin by Jeff Bezos and of course Burt Rutans followup to the SpaceShipOne.
And even if these efforts all fail, there are plenty of relatively cheap launchers available today, most notably the russian proton and the zenit sea launch.
And we most definitely do not need a new shuttle. We need cheap access to space, and the shuttle was a total failure in this regard.
The first test flight of Bigelow Aerospace will use the cheap Falcon V launcher that is currently developed by Elon Musk, the former owner of paypal. So there is a good cooperation between the different private companies in the alt.space community.
Impulse of a 1000kg payload at geostationary altitude:
r_GEO=42 164 000 m v_GEO=3 066 m/s p_GEO=3 066 000 kg*m/s
Amout of force to transfer this impulse in two days:
t=2 days=172800s F=dp/dt=p_GEO/t=17.74N
So you need a sideways force of just 17N at the attachment point. The tension at the attachment point is at least of the same magnitude as the payload, or about 10000N. So the angle at the attachment point is less than arctan(17/10000)=0.1 degrees.
So to transfer the momentum to the payload, the tether at the attachment point has to be 0.1 degrees to the west instead of perpendicular. Not a big deal. --
Slashdot Mirror
The UN has got to be the most currupt buerocracy on the planet. They just had the biggest corruption scandal ever. Bigger than ENRON and WorldCom combined.
Oh, and their peacekeepers are busy abusing children.
With the tsunami aid effort, they were mostly concerned with holding meetings in 5 star hotels while other people did the real work.
They also constantly bash israel without ever mentioning that the palestinean side is not exactly peaceful either.
And they have recently decided that what is happening in sudan is not genocide. I guess they will decide it was genocide after all when everybody is dead. Like they did in ruanda.
The UN should be dismantled or at least seriously reformed. They should not get any more responsibilities, since they are obviously unable to cope with the responsibilities they have in an ethical manner.
I guess they are not sure themselves how much they can reuse.
They have spent quite a lot of time and mass on the first stage to make it reusable. For example there is a mortar-deployed parachute on the first stage. But since this has never been done before, they are not sure in what shape the stage will be after the water landing.
In the best case, they will just have to replace some parts (ablative nozzle, interstage etc), refuel it and relaunch it. In the worst case they can only reuse the high value parts like the engine and the valves.
We will find out soon enough.
The reason falcons will be cheap is not because they use cheap components, but because they have a different approach than old defense contractors like boeing and lockheed.
In fact they use very high quality materials such as a titanium thrust frame in the first stage. But they can afford that because the first stage is reusable.
They also try to avoid any hazardous materials like explosive bolts and dangerous chemicals since that makes working with the rocket before launch much safer and thus cheaper. The falcon I is the first rocket that is allowed to fly without an explosive flight termination system because of redundant thrust termination systems. So there is no bomb on board.
Take a look at the falcon launch complex. It is basically just a simple concrete building and a flatbed truck. The satellite is integrated while the rocket is horizontal, so they do not need a huge building for satellite integration.
The launch control center is a truck trailer, so they only need one for all launch pads and do not have all that expensive computer hardware sitting around idle.
Now compare that with the launch complex for the boeing delta IV. There is a vertical integration building for fitting the payload, a huge umbilical tower and all kinds of facilities to handle the huge quantities of liquid hydrogen that the delta IV needs.
The only large rocket that has a comparably clean launch pad like the falcon is the russian/ukrainian Zenit (also used by Sea Launch), which is also the cheapest of its class.
The falcon I will also have a very benign launch environment for the payload. The amount of vibration is much lower than with other rockets since the falcon does not use solids. See the payload users guide for details.
Zope page templates (ZPT) are quite cool. But you can use them without zope in a pure python program. And the persistence and undo offered by the ZODB (Zope object database) is also quite useful.
There are multiple backends available, and you can get really good performance and security by using the file system backend of the ZODB on top of reiser4.
Most of the performance problems of the plone/zope combo come from plone. So my advice as someone who had the misfortune to optimize a plone/zope based commercial website: take a good look at zope, but stay the hell away from plone.
Zope is a nice application server, but not exactly fast. It has nice abstractions like acquisition to do very complex web applications with only a few lines of code.
Plone adds more layers of abstraction and makes the whole even slower. It is almost as if the plone designers read a book about advanced OO concepts and wanted to implement every single concept they just learned about in a single application.
The only way to get decent performance out of a plone/zope setup is to put a squid proxy in front of it, but that causes a lot of problems with dynamic content.
The documentation is also horrible. If you are lucky it is just incomplete and out of date, but in most cases there is none at all.
If you want to do a small application with less than one hit per second, go ahead. But for a big site: forget it.
"I guarantee you these 20 people use the labor of others a lot more than they use their own labor. Why do we always obsess over people who are supposedly the best at something?"
That is a typical thing to say for a communist.
Why is it that you have such problems with admitting that some individuals are more gifted than others?
And while you claim to despise individualism, you worship individuals like that mass murderer che guevara.
How dare they omit john backus? He invented fortran, which is still the most often used language for scientific calculations. And he pioneered functional programming.
He deserves to be on top of this list for this publication alone.
List in C# and ArrayList in java are both backed by arrays, so they should have the best performance if you don't want to add or remove elements from the middle of the list.
The only way to get good performance in java would be to use an int[].
An anonymous inner class in java can only refer to final variables from the local scope. So you define a final array with one element to copy something out of the inner class context.
l Limitation
Here is a good example:
http://c2.com/cgi/wiki?ClosuresThatWorkAroundFina
Java has anonymous *classes* since 1.1. But that is not the same as anonymous methods. And C# 2.0 has real closures and none of the limitations of java inner classes. No need for the "final array of one element" hack, if you know what I mean.
The java generics system just saves typing and ensures type-safety for collections. But it does nothing about the problem of excessive boxing and unboxing that plagued java collection classes from 1.0 on.
For example if you have an ArrayList<Integer> in java, it internally uses an object[] to store the elements of the array. So everytime you write a new value to the ArrayList<Integer> by e.g. calling list.Add(i), a new object is allocated on the heap.
A List<int> in C# on the other hand uses an int[] internally, so adding or changing an element in the List<int> will result in no boxing/unboxing at all. A List will be just as fast as an int[] since the indexer method will be inlined.
The performance difference is dramatic: try creating an ArrayList<Integer>/List<int> and filling it with 1000000 numbers. The C# code will run 10 to 20 times faster, while the java version will use 20 bytes per Integer instead of 4 bytes per Integer like the C# version.
I am currently not at home, but if somebody is interested I will post a benchmark later.
Slight correction: the atlas ballon tanks are made from high quality stainless steel. Other than that you are correct. The atlas was an amazing design.
With all the needle jokes and condom comparisons one could get the impression that these inflatable modules are less rugged than the aluminium modules now used for the ISS.
This is not the case. They are made out of multiple layers of kevlar (the same stuff that bulletproof vests are made of). In tests with the NASA-designed transhab inflatable module they have proven to be much more resistant to space debris than aluminium hulls.
Also even if a particulary large piece of space debris should punch a hole in one of these modules, they are so big that there would be plenty of time to evacuate them before the pressure drops too much. A long-time station will probably also have a repair kit on board.
Third, the problem of space debris is particulary severe in low earth orbit. But in a higher earth orbit there is much less space debris, and the stuff that is there moves with much lower relative velocities. So from a space debris point of view low earth orbit is the absolute worst case. A station at an Earth/Moon lagrange point or in deep space would need little or no space debris protection.
A binary format for X3D is being defined. X3D supports multiple file encodings describing the same abstract model.
Nice to hear that. That will increase the chances of X3D being accepted as a true standard tremendously.
Maybe that is why VRML and X3D were not successful. Storing binary data like 3D vector data and texture data in a text file and then compressing the text file to get acceptable file sizes is just plain stupid.
Binary storage for 3D data makes a lot more sense since it is more compact and easier to parse, and there are also standards such as the IEEE float and double standard.
But nowadays everything has got to be XML, even if it does not make any sense at all. XML is fine for configuration files and office documents, but for image and vector data it is just not the right tool.
High velocity sniper rifles have muzzle velocities of about 1000m/s. Worst-case space debris has velocities of 8000m/s, so it has 64 times as much energy per mass.
But it is not as bad as it sounds. First of all space debris is not designed to penetrate armor. Usually it is quite small stuff.
And when a piece of space debris hits the outer shell of your space station it instantly vaporizes. So the inner shells of your space station just have to cope with vapor.
Atlas V and Delta IV are nice launch vehicles for expensive spysats, but they are most definitely not cheap.
A proton flight can be had for as little as 20 million USD. A comparable atlas or delta costs upwards of 100 million USD.
And by the way: most failures with the russian launchers were with the last stage, which you would not need anyway for low earth orbit flights.
The first space habitats will be in low earth orbit where the earth magnetosphere provides some protection from charged particle radiation from the sun and deep space.
And the bigelow designs will use water-filled bladders on the inside of the wall to provide additional radiation protection. If you want to go outside low earth orbit, just add more water.
For solar storms there will be a radiation shelter with very thick water walls.
Its the same kind of material that is used in bulletproof vests. But it is multilayered and much thicker. So of course it is micro-meteorite proof.
Tests with the NASA transhab design have shown that multi-layered inflatables are more resistant to space debris than aluminium hulls. That should come as no surprise since the materials involved have much more (mass specific) tensile strength than aluminium.
Have you ever seen a flak vest made from aluminium?
I think accidents will not be a big deal. People risk their lives for all kinds of crazy shit like climbing the mount everest, so why should they not be allowed to risk their lives to live in space?
Early aviation history is full of deadly accidents. And people have still continued to build and fly airplanes.
If some nanny state government like the peoples republic of california will outlaw private space flight, the development will simply move somewhere else. Even if private spaceflight is outlawed in the whole US, there are other countries in the world.
There is plenty of stuff that can be done better in space once the transportation costs go down. You have unlimited quantities of hard vacuum, free energy from the sun 24h a day, access to very low temperatures with a simple radiator and perfect isolation from the earth biosphere.
So everything that could be harmful to the biosphere, requires lots of energy, hard vacuum or cryogenic temperatures will be more economical in space once the transportation problem is solved.
The first thing will probably be stuff like genetic engineering and bioweapons research. Then there will be solar power satellites. And once you get these in place most of the heavy industry will move to space (high earth orbit, to be precise).
Just think about the advantages: you can build a huge industrial complex without people suing you about the noise, the pollution etc.
There are plenty of people developing new space transports. Most notably spacex. But there are many more such as the mysterious Blue Origin by Jeff Bezos and of course Burt Rutans followup to the SpaceShipOne.
And even if these efforts all fail, there are plenty of relatively cheap launchers available today, most notably the russian proton and the zenit sea launch.
And we most definitely do not need a new shuttle. We need cheap access to space, and the shuttle was a total failure in this regard.
The first test flight of Bigelow Aerospace will use the cheap Falcon V launcher that is currently developed by Elon Musk, the former owner of paypal. So there is a good cooperation between the different private companies in the alt.space community.
I also like this very much. But it is not just mouse gestures. It is a radial menu that can be used somewhat like mouse gestures.
But since you get visual feedback it is much easier to memorize the gestures than with "invisible" gestures".
It is hard to describe, so just check it out.
OK, so lets do some basic newtonian mechanics
Laws of motion:
p=m*v
F=dp/dt
Impulse of a 1000kg payload at geostationary altitude:
r_GEO=42 164 000 m
v_GEO=3 066 m/s
p_GEO=3 066 000 kg*m/s
Amout of force to transfer this impulse in two days:
t=2 days=172800s
F=dp/dt=p_GEO/t=17.74N
So you need a sideways force of just 17N at the attachment point. The tension at the attachment point is at least of the same magnitude as the payload, or about 10000N. So the angle at the attachment point is less than arctan(17/10000)=0.1 degrees.
So to transfer the momentum to the payload, the tether at the attachment point has to be 0.1 degrees to the west instead of perpendicular. Not a big deal.
--