I heard Stallman lecture on intellectual property a while back, and the big problem is software patents and how the big guys can use them to prevent the little guys from doing ANYTHING. If you have some software the uses exclusive-OR to redraw a graphics cursor, well, you are infringing.
If I use a patented washer in some mechanism that I sell, well, I can buy that washer from a supplier that holds patent rights. If I use a patented software hack, only a component in my system, I can get shut down if I get caught.
The big guys sue each other over patents but end up cross-licensing each other into a big guys club.
Stallman's concern was that in the software land-rush patent-grab where the most obvious stuff gets patented but it is tres expensive to challenge any of those patents once they get issued, one wouldn't be able to write any software at all.
What the GPL does is stake out territory, not only in high-level stuff like OS's and compilers, but also low-level stuff like algorithms. GPL code lying around makes a strong case for prior art that someone cannot patent, say, a compression algorithm found in GPL's source somewhere.
The extension of this, is that if Microsoft needs a compression algorithm found in a popular piece of GPL code, they will have to prove that they did not look at the popular code and hence have to open-source all their stuff, which they are not eager to do.
IMO the GPL is a fair way of fighting the software patent land grab, and software gets written on account of government funding at universities and gets GPL's, well, Microsoft needs to suck it in.
Air-breathing propulsion is the long-held dream for achieving orbit without the weight penalty of carrying liquid oxygen -- using liquid hydrogen fuel, the oxygen weighs several times more than the fuel. The problem is not that there is no air in space -- you could accelerate to orbital speed in the air at high altitudes if you can tolerate the heat.
The problem is that the faster you go, the more energy you impart on the air you scoop up. Even if you could manage the nose and wing shock waves that the vehicle does not burn up, the compression heating caused by the air meeting the shock fronts of your engine inlet will burn your engine up (see all the remarks about the temperature at which titanium turns to taffy as the true speed limit on the SR-71). If you have a pure ram jet, you will reach the limit where the air itself burns up (turns to ionized plasma into which you cannot impart additional thrust by burning any fuel in it).
The scram jet idea is that let the air blow through your engine at supersonic speeds so as to not compress it to the point where it literally burns up (ionizes). You need to burn hydrogen so that the flame does not blow out. Some scram jets are little more than a bunch of fins you stick out to generate shock waves into which you squirt the hydrogen fuel. The proposed vehicle is to test the scram jet.
Problem is that you have to accelerate a vehicle to scramjet speeds (Mach 5). How much more can you accelerate in scram jet mode before you need to turn to pure rocket? Can a scramjet produce net thrust at all or is it a figment of the aerodynamicist's imagination.
While the scram jet idea has been around for 40 years and it remains a worthwhile research project, it proved to be a billion-dollar rathole down which the National Aero Space Plane budget was poured down in the early 80's with nothing to show for as a space launcher. Air breathing space launch may be a good idea, but there are a lot of details to be worked out.
So called geothermal heat is of course the ground-source heat pump, and as such, you have the performance limitations of a heat pump.
Let's say you get a coefficient of performance of 3.5, electricity costs 9 cents/kwHr, gas costs $1.10 a therm (ouch, it was only 55 cents/therm last year). A kwHr supplies 3400 BTU times COP of 3.5 or about 12000 BTU. A therm is 10^5 BTU. Your heat pump therm costs 75 cents while your high-efficiency gas furnace therm (96 percent) costs $1.15. So I guess there is a considerable saving, but that is only because gas has doubled in price, and it is not clear that the electric won't get more expensive because a lot of the new electric generators are gas-fired.
What does the ground-source unit gain over a air source heat pump (essentially central AC switched over to heat pump mode)? You can get air-source units with COP of around 3.5, but that COP falls off as the outside temperature reaches freezing (32 F, 0 C), and much below that you are essentially using resistive heat with a COP of 1. What the ground source unit buys you for digging up your yard is the ability to operate tha heat pump when it is colder outside.
But wait. My house needs roughly 500 BTU's per degree F differential per hour. My high-efficiency gas furnace on the quiet, low-electricity using 600 CFM blower setting supplies about 50,000 BTU's/hr, giving me enough heat down to 30 below. Now 50,000 BTU's out of a heat pump needs a hurricane of about 2500 CFM's (a heating/cooling ton is 12000 BTU/hr and you need 400 CFM/ton for AC/heat pumps)-- if it takes a 70 W blower to push 600 CFM's through my ducts, it will require about a 5 kW motor to blow 2500 CFM's (power goes as the cube of air velocity), and I don't know if I can stand the racket.
So I think the ground-source heat pump probably has a narrow climate zone of applicability, where it gets cold enough to have an advantage over the air-source unit yet not too cold that you run into capacity limits on the air handler.
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Oh boy, guess I am in real trouble from my "gas engine" model airplane days.
If I use a patented washer in some mechanism that I sell, well, I can buy that washer from a supplier that holds patent rights. If I use a patented software hack, only a component in my system, I can get shut down if I get caught. The big guys sue each other over patents but end up cross-licensing each other into a big guys club.
Stallman's concern was that in the software land-rush patent-grab where the most obvious stuff gets patented but it is tres expensive to challenge any of those patents once they get issued, one wouldn't be able to write any software at all.
What the GPL does is stake out territory, not only in high-level stuff like OS's and compilers, but also low-level stuff like algorithms. GPL code lying around makes a strong case for prior art that someone cannot patent, say, a compression algorithm found in GPL's source somewhere.
The extension of this, is that if Microsoft needs a compression algorithm found in a popular piece of GPL code, they will have to prove that they did not look at the popular code and hence have to open-source all their stuff, which they are not eager to do.
IMO the GPL is a fair way of fighting the software patent land grab, and software gets written on account of government funding at universities and gets GPL's, well, Microsoft needs to suck it in.
The problem is that the faster you go, the more energy you impart on the air you scoop up. Even if you could manage the nose and wing shock waves that the vehicle does not burn up, the compression heating caused by the air meeting the shock fronts of your engine inlet will burn your engine up (see all the remarks about the temperature at which titanium turns to taffy as the true speed limit on the SR-71). If you have a pure ram jet, you will reach the limit where the air itself burns up (turns to ionized plasma into which you cannot impart additional thrust by burning any fuel in it).
The scram jet idea is that let the air blow through your engine at supersonic speeds so as to not compress it to the point where it literally burns up (ionizes). You need to burn hydrogen so that the flame does not blow out. Some scram jets are little more than a bunch of fins you stick out to generate shock waves into which you squirt the hydrogen fuel. The proposed vehicle is to test the scram jet.
Problem is that you have to accelerate a vehicle to scramjet speeds (Mach 5). How much more can you accelerate in scram jet mode before you need to turn to pure rocket? Can a scramjet produce net thrust at all or is it a figment of the aerodynamicist's imagination.
While the scram jet idea has been around for 40 years and it remains a worthwhile research project, it proved to be a billion-dollar rathole down which the National Aero Space Plane budget was poured down in the early 80's with nothing to show for as a space launcher. Air breathing space launch may be a good idea, but there are a lot of details to be worked out.
So called geothermal heat is of course the ground-source heat pump, and as such, you have the performance limitations of a heat pump.
Let's say you get a coefficient of performance of 3.5, electricity costs 9 cents/kwHr, gas costs $1.10 a therm (ouch, it was only 55 cents/therm last year). A kwHr supplies 3400 BTU times COP of 3.5 or about 12000 BTU. A therm is 10^5 BTU. Your heat pump therm costs 75 cents while your high-efficiency gas furnace therm (96 percent) costs $1.15. So I guess there is a considerable saving, but that is only because gas has doubled in price, and it is not clear that the electric won't get more expensive because a lot of the new electric generators are gas-fired.
What does the ground-source unit gain over a air source heat pump (essentially central AC switched over to heat pump mode)? You can get air-source units with COP of around 3.5, but that COP falls off as the outside temperature reaches freezing (32 F, 0 C), and much below that you are essentially using resistive heat with a COP of 1. What the ground source unit buys you for digging up your yard is the ability to operate tha heat pump when it is colder outside.
But wait. My house needs roughly 500 BTU's per degree F differential per hour. My high-efficiency gas furnace on the quiet, low-electricity using 600 CFM blower setting supplies about 50,000 BTU's/hr, giving me enough heat down to 30 below. Now 50,000 BTU's out of a heat pump needs a hurricane of about 2500 CFM's (a heating/cooling ton is 12000 BTU/hr and you need 400 CFM/ton for AC/heat pumps)-- if it takes a 70 W blower to push 600 CFM's through my ducts, it will require about a 5 kW motor to blow 2500 CFM's (power goes as the cube of air velocity), and I don't know if I can stand the racket.
So I think the ground-source heat pump probably has a narrow climate zone of applicability, where it gets cold enough to have an advantage over the air-source unit yet not too cold that you run into capacity limits on the air handler.